Metabolism arsenic

The literature emphasizes that arsenic metabolism and toxicity vary greatly between species and that its effects are significantly altered by numerous physical, chemical, and biological modifiers. Adverse health effects, for example, may involve respiratory, gastrointestinal, cardiovascular, and hematopoietic systems, and may range from reversible effects to cancer and death, depending partly on the physical and chemical forms of arsenic tested, the route of administration, and the dose. 

Arsenic metabolism and effects are significantly influenced by the organism tested, the route of administration, the physical and chemical form of the arsenical, and the dose. 

Wrench, J., S.W. Fowler, and M.Y. Unlu. 1979. Arsenic metabolism in a marine food chain. Mar. Pollut. Bull. 10 18-20. 

This research is an outgrowth of an earlier project which sought to characterize the mechanism of arsenic metabolism in a population currently drinking arsenic-contaminated water in Taiwan. There were three parts to the study, a cohort study, a case control study for skin cancer, and a study of intra-individual variability associated with chronic arsenic exposure. The latter three research projects are complete and being submitted for publication. The results of this research are highly relevant since they indicate that alterations in methylation capacity may affect arsenic carcinogenesis. 

Ahsan H et al Arsenic metabolism, genetic susceptibility, and risk of premalignant skin lesions in Bangladesh. Cancer Epidemiol Biomarkers Prev 2007 16 1270. [PMID 17548696]... 

Gamble MV Folate and arsenic metabolism A double-blind, placebo-controlled folic acid supplementation trial in Bangladesh. Am J Clin Nutr 2006 84 1093. [PMID 17093162]... 

Gong Z et al Determination of arsenic metabolic complex excreted in human urine after administration of sodium 2,3-dimercapto-l-propane sulfonate. Chem Res Toxicol 2002 15 1318. [PMID 12387631]... 

Hall, M Gamble, M Slavkovich, V. et al. (2007) Determinants of arsenic metabolism Blood arsenic metabolites, plasma folate, cobalamin, and homocysteine concentrations in maternal-newborn pairs. Environmental Health Perspectives, 115 (10), 1503-9. 

Thomas, D.J. (2007) Molecular processes in cellular arsenic metabolism. Toxicology and Applied Pharmacology, 222(3), 365-73. 

Phytoremediation with living plants may be improved through genetic engineering and a thorough understanding of arsenic metabolism and detoxification in plants (Montes-Baydn et al., 2004). As an initial step, Montes-Bay on et al. (2004) studied arsenic metabolism in Brassica juncea (Indian mustard). They found that some of the arsenic was associated with thiol groups in the plant. 

Dhankher, O.P. 2005. Arsenic metabolism in plants An inside story. New Phytologist, 168 503-5. 

Schmuck, E.M., Board, P.G., Whitbread, A.K., Tetlow, N., Cavanaugh, J.A., Blackburn, A.C., Masoumi, A. (2005). Characterization of the monomethylarsonate reductase and dehydroascorbate reductase activities of Omega class glutathione transferase variants implications for arsenic metabolism and the age-at-onset of Alzheimer s and Parkinson s diseases. Pharmacogenet. Genomics 15 493-501. 

Edmonds JS and Francesconi KA (1998) Arsenic metabolism in aquatic ecosystems. In Langston WJ and Bebianno MJ, eds. Metal metabolism in aquatic environments. Chapter 6, pp. 159-183. Chapman Hall, London. 

Le XC, Lu X, Ma M, Cullen WR, Aposhian HV and Zheng B (2000a) Speciation of key arsenic metabolic intermediates in human urine. Anal Chem 72 5172-5177. 

Simpler procedures mainly starting with liquids (water, urine, blood, other body fluids) often suffice in that they permit a quick determination of the sum or of toxic forms of arsenic - that is. As ", As, MMA and DMA in laboratory routine. More sophisticated procedures, however, are required for scientific investigations on arsenic metabolism in humans, animals and plants and the identification and quantification of hitherto unknown arsenic species in the environment - a research field that is now just at its beginning. 

Recently, the successful treatment of a suicidal AS2O3 ingestion (most probably >0.6 g) with DMPS was studied by investigation of species excretion. The initial total As concentration was about 215 mg L and this fell 1000-fold after eight days of DMPS therapy. Arsenic species percentages initially excreted were As " (41%), As (38.4%), MMA (2.6%), initially no DMA, later only small amounts, and traces of an unknown As species. The missed occurrence of DMA was assumed to be an almost complete inhibition of the second methylation step in arsenic metabolism (see Section 6.5.2), possibly because of the high DMPS dosage (Heinrich-Ramm etal. 

WiCKENHEISEE EB, MiCHALKE K, DeESCHEE C, Hienee AV and Hensel R (1998) Development and application of liquid and gas-chromatographic speciation techniques with element specific (ICP-MS) detection to the study of anaerobic arsenic metabolism. Fresenius J Anal Chem 362 498-501. 

On the one hand there are relatively simple procedures that allow a quick determination of the sum of inorganic arsenic, i.e. As(lll) and As(V). MMA and DMA for epidemiological studies, occupational exposure, intoxication, and poisoning. On the other hand, more complex and detailed procedures are required for scientific investigations on arsenic metabolism in mammals and man. 

J Feldmann, K John, P Pengprecha. Arsenic metabolism in seaweed-eating sheep from northern Scotland. Fresenius J Anal Chem 368 116-121, 2000. 

JP Buchet, R Lauwerys. Inorganic arsenic metabolism in humans. In WR Chappell, CC Abernathy, CR Cothern, eds. Arsenic Exposure and Health. Norwood, UK Science and Technology Letters, 1994, pp 181-189. 

In addition to plasmid arsenic resistance that is well understood and for which clusters of genes have been isolated and sequenced, there are bacterial arsenic metabolism systems that involve oxidation of arsenite to arsenic. Arsenite oxidation by aerobic pseudomonads was first found with bacteria isolated from cattle dipping solutions where arsenicals were used as agents against ticks around the time of World War I. They were subsequently isolated by Turner and Legge... 

Her most recent scientific contributions were in the areas of bacterial selenium and arsenic metabolism. Her interest in bioremediation began with selenium-contaminated water found in the San Joaquin Valley in California, from which she isolated the first bacterium able to respire with selenate (reducing it to selenite and then to elemental selenium) using acetate as the electron donor/ carbon source. This organism was found to represent a new genus and named Thauera selenatis. She studied the organism extensively for the purpose of selenium bioremediation. This involved the design and implementation of lab-scale and then pilot-scale reactors. 

T. Agusa, J. Fujihara, H. Takeshita, H. Iwata (2011) Individual variations in inorganic arsenic metabolism assoeiated with AS3MT genetic polymorphisms. 7nt. J. Mol. Set., 12, 2351-2382. 

Other arsenic species, like the trivalent methylated intermediates of arsenic metabolism predicted by Challenger, were for many years fairly elusive, because of their instability against oxygen and harsh extraction conditions. The recently identified arsenic-glutathione and arsenite-phytochelatin complexes suffer from the same problem, and can only be stabilized in acidic extracts. 

Ingested arsenate and arsenite are taken up in the intestine and transported by the blood into the liver, which is the major site of arsenic metabolism before excretion by urine. 

---