@article {330, title = {Plasmid DNA damage caused by methylated arsenicals, ascorbic acid and human liver ferritin}, journal = {Toxicology Letters}, volume = {133}, number = {1}, year = {2002}, note = {ISI Document Delivery No.: 575QMTimes Cited: 46Cited Reference Count: 499th International Congress of ToxicologyJUL 08-12, 2001BRISBANE, AUSTRALIA}, month = {Jul}, pages = {47-57}, type = {Proceedings Paper}, abstract = {Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, P < 0.05) and by DMA(III) was much higher (16.3 nM/min, P < 0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe2+ concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.}, keywords = {arsenic, BIOCHEMICAL PARAMETERS, CARCINOGENESIS, DIMETHYLARSINIC ACID, dimethylarsinous acid, DMA(111), DNA damage, ENDOTHELIAL-CELLS, human liver ferritin, INDUCTION, INORGANIC ARSENICS, iron, MICE, MONOMETHYLARSONOUS ACID, reactive oxygen, species, STRAND BREAKS}, isbn = {0378-4274}, url = {://000176959200005}, author = {Ahmad, S. and Kitchin, K. T. and Cullen, W. R.} } @article {4862, title = {Determination of monomethylarsonous acid, a key arsenic methylation intermediate, in human urine}, journal = {Environmental Health Perspectives}, volume = {108}, number = {11}, year = {2000}, note = {ISI Document Delivery No.: 373XPTimes Cited: 101Cited Reference Count: 48}, month = {Nov}, pages = {1015-1018}, type = {Article}, abstract = {In this study we report on the finding of monomethylarsonous acid [MMA(III)I in human urine. This newly identified arsenic species is a key intermediate in the metabolic pathway of arsenic biomethylation, which involves stepwise reduction of pentavalent to trivalent arsenic species followed by oxidative addition of a methyl group. Arsenic speciation was carried out using ion-pair chromatographic separation of arsenic compounds with hydride generation atomic fluorescence spectrometry detection. Speciation of the inorganic arsenite [As(III)], inorganic arsenate [As(V)], monomethylarsonic acid [MMA(V)], dimethylarsinic acid [DMA(V)], and MMA(III) in a urine sample was complete in 5 min. Urine samples collected from humans before and after a single oral administration of 300 mg sodium 2,3-dimercapto-1-propane sulfonate (DMPS) were analyzed for arsenic species. MMA(III) was found in 51 out of 123 urine samples collected from 41 people in inner Mongolia 0-6 hr after the administration of DMPS. MMA(III)in urine samples did not arise from the reduction of MMA(V) by DMPS. DMPS probably assisted the release of MMA(III) that was formed in the body. Along with the presence of MMA(III), there was an increase in the relative concentration of MMA(V) and a decrease in DMA(V) in the urine samples collected after the DMPS ingestion.}, keywords = {3-dimercapto-1-propane sulfonate, ARSENIC SPECIATION, BIOMARKERS, CARCINOGENESIS, CHEMICAL FORMS, DIMETHYLARSINIC ACID, ENZYMATIC METHYLATION, EXCRETION, EXPOSURE, GLUTATHIONE-REDUCTASE, INGESTION, METABOLISM, METABOLITES, METHYLATION, MONOMETHYLARSONOUS ACID, sodium 2, SPECIATION, trivalent methylarsenic species, urine metabolites}, isbn = {0091-6765}, url = {://000165315600019}, author = {Le, X. C. and Ma, M. S. and Lu, X. F. and Cullen, W. R. and Aposhian, H. V. and Zheng, B. S.} } @article {4535, title = {Sample preparation and storage can change arsenic speciation in human urine}, journal = {Clinical Chemistry}, volume = {45}, number = {11}, year = {1999}, note = {ISI Document Delivery No.: 251HUTimes Cited: 70Cited Reference Count: 543rd International Conference on Arsenic Exposure and Health EffectsJUL 12-15, 1998SAN DIEGO, CALIFORNIA}, month = {Nov}, pages = {1988-1997}, type = {Proceedings Paper}, abstract = {Background: Stability of chemical speciation during sample handling and storage is a prerequisite to obtaining reliable results of trace element speciation analysis. There is no comprehensive information on the stability of common arsenic species, such as inorganic arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid, dimethylarsinic acid, and arsenobetaine, in human urine. Methods: We compared the effects of the following storage conditions on the stability of these arsenic species: temperature (25, 4, and -20 degrees C), storage time (1, 2, 4, and 8 months), and the use of additives (HCl, sodium azide, benzoic acid, benzyltrimethyl ammonium chloride, and cetylpyridinium chloride). HPLC with both inductively coupled plasma mass spectrometry and hydride generation atomic fluorescence detection techniques were used for the speciation of arsenic. Results: We found that all five of the arsenic species were stable for up to 2 months when urine samples were stored at 4 and -20 degrees C without any additives. For longer period of storage (4 and 8 months), the stability of arsenic species was dependent on urine matrices. Whereas the arsenic speciation in some urine samples was stable for the entire 8 months at both 4 and -20 degrees C, other urine samples stored under identical conditions showed substantial changes in the concentration of As(III), As(V), monomethylarsonic acid, and dimethylarsinic acid. The use of additives did not improve the stability of arsenic speciation in urine. The addition of 0.1 mol/L HCl (final concentration) to urine samples produced relative changes in inorganic As(III) and As(V) concentrations. Conclusions: Low temperature (4 and -20 degrees C) conditions are suitable for the storage of urine samples for up to 2 months. Untreated samples maintain their concentration of arsenic species, and additives have no particular benefit. Strong acidification is not appropriate for speciation analysis. (C) 1999 American Association for Clinical Chemistry.}, keywords = {CARCINOGENESIS, CHEMICAL FORMS, DIMETHYLARSINIC ACID, DRINKING-WATER, EXCRETION, EXPOSURE, MASS-SPECTROMETRIC DETECTION, METABOLITES, METHYLATION PATTERNS, PERFORMANCE LIQUID-CHROMATOGRAPHY}, isbn = {0009-9147}, url = {://000083440300015}, author = {Feldmann, J. and Lai, V. W. M. and Cullen, W. R. and Ma, M. S. and Lu, X. F. and Le, X. C.} }