The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform
Elaine M Leslie - One of the best experts on this subject based on the ideXlab platform.
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accumulation and transport of roxarsone arsenobetaine and inorganic arsenic using the human immortalized caco 2 cell line
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Qingqing Liu, Elaine M LeslieAbstract:Roxarsone (Rox), an Organoarsenic Compound, served as a feed additive in the poultry industry for more than 60 years. Residual amounts of Rox present in chicken meat could give rise to potential human exposure to Rox. However, studies on the bioavailability of Rox in humans are scarce. We report here the accumulation and transepithelial transport of Rox using the human colon-derived adenocarcinoma cell line (Caco-2) model. The cellular accumulation and transepithelial passage of Rox in Caco-2 cells were evaluated and compared to those of arsenobetaine (AsB), arsenite (AsIII), and arsenate (AsV). When Caco-2 cells were exposed to 3 μM Rox, AsB, and AsIII separately for 24 h, the maximum accumulation was reached at 12 h. After 24-h exposure, the accumulated Rox was 6–20 times less than AsB and AsIII. The permeability of Rox from the apical to basolateral side of Caco-2 monolayers was similar to AsV but less than AsIII and AsB. The results of lower bioavailability of Rox are consistent with previous observat...
Peter Christie - One of the best experts on this subject based on the ideXlab platform.
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sorption mechanisms of diphenylarsinic acid on ferrihydrite goethite and hematite using sequential extraction ftir measurement and xafs spectroscopy
Science of The Total Environment, 2019Co-Authors: Meng Zhu, Haibo Zhang, Fang Song, Yongming Luo, Peter ChristieAbstract:Abstract Diphenylarsinic acid (DPAA) is an Organoarsenic Compound derived from abandoned chemical weapons. DPAA sorption by iron (hydr)oxides is of considerable importance but remains largely unexplored. The current study aimed at investigating the sorption mechanisms of DPAA on ferrihydrite, goethite and hematite using both macroscopic sorption kinetics and sequential extraction procedure (SEP) as well as microscopic Fourier transformed infrared (FTIR) and extended X-ray absorption fine structure (EXAFS) spectroscopic techniques. Sorption kinetics studies show that >93% of added DPAA (4–100 mg L−1) was sorbed on ferrihydrite and hematite within 5 min, while only 84% of added DPAA (100 mg L−1) was sorbed on goethite after 24 h. The sequential extraction results and FTIR measurements reveal that DPAA formed simultaneously inner- and outer-sphere complexes on goethite and hematite, but predominantly inner-sphere complexes on ferrihydrite with limited formation of outer-sphere complexes (
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sorption mechanisms of diphenylarsinic acid on ferrihydrite goethite and hematite using sequential extraction ftir measurement and xafs spectroscopy
Science of The Total Environment, 2019Co-Authors: Xuefeng Hu, Haibo Zhang, Fang Song, Chen Tu, Peter ChristieAbstract:: Diphenylarsinic acid (DPAA) is an Organoarsenic Compound derived from abandoned chemical weapons. DPAA sorption by iron (hydr)oxides is of considerable importance but remains largely unexplored. The current study aimed at investigating the sorption mechanisms of DPAA on ferrihydrite, goethite and hematite using both macroscopic sorption kinetics and sequential extraction procedure (SEP) as well as microscopic Fourier transformed infrared (FTIR) and extended X-ray absorption fine structure (EXAFS) spectroscopic techniques. Sorption kinetics studies show that >93% of added DPAA (4-100 mg L-1) was sorbed on ferrihydrite and hematite within 5 min, while only 84% of added DPAA (100 mg L-1) was sorbed on goethite after 24 h. The sequential extraction results and FTIR measurements reveal that DPAA formed simultaneously inner- and outer-sphere complexes on goethite and hematite, but predominantly inner-sphere complexes on ferrihydrite with limited formation of outer-sphere complexes (<15%). A combination of SEP, FTIR and EXAFS techniques further enables identification of the interfacial reactions between DPAA and solid surfaces of iron (hydr)oxides and the mechanisms involved. Results indicate that DPAA interacted with these iron (hydr)oxides via (1) electrostatic attraction or hydrogen bonding, (2) surface complexation and (3) complexation embedded inside the mineral particles. EXAFS studies further demonstrate that DPAA formed mainly bidentate binuclear corner-sharing (2C) complexes regardless of the iron substrate, with As-Fe distances at 3.19-3.32 A. Comparison of these results with available data in the literature on inorganic, methyl and phenyl arsenics (As) suggests that it is the phenyl group substitution that finally determines the predominance of 2C complexes. Results from the present study will improve our knowledge of DPAA interaction with solid surfaces and may help in the prediction of the environmental fate and environmental risk management of DPAA in the soil-water system.
Qingqing Liu - One of the best experts on this subject based on the ideXlab platform.
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accumulation and transport of roxarsone arsenobetaine and inorganic arsenic using the human immortalized caco 2 cell line
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Qingqing Liu, Elaine M LeslieAbstract:Roxarsone (Rox), an Organoarsenic Compound, served as a feed additive in the poultry industry for more than 60 years. Residual amounts of Rox present in chicken meat could give rise to potential human exposure to Rox. However, studies on the bioavailability of Rox in humans are scarce. We report here the accumulation and transepithelial transport of Rox using the human colon-derived adenocarcinoma cell line (Caco-2) model. The cellular accumulation and transepithelial passage of Rox in Caco-2 cells were evaluated and compared to those of arsenobetaine (AsB), arsenite (AsIII), and arsenate (AsV). When Caco-2 cells were exposed to 3 μM Rox, AsB, and AsIII separately for 24 h, the maximum accumulation was reached at 12 h. After 24-h exposure, the accumulated Rox was 6–20 times less than AsB and AsIII. The permeability of Rox from the apical to basolateral side of Caco-2 monolayers was similar to AsV but less than AsIII and AsB. The results of lower bioavailability of Rox are consistent with previous observat...
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Accumulation and Transport of Roxarsone, Arsenobetaine, and Inorganic Arsenic Using the Human Immortalized Caco‑2 Cell Line
2016Co-Authors: Qingqing Liu, Elaine M. LeslieAbstract:Roxarsone (Rox), an Organoarsenic Compound, served as a feed additive in the poultry industry for more than 60 years. Residual amounts of Rox present in chicken meat could give rise to potential human exposure to Rox. However, studies on the bioavailability of Rox in humans are scarce. We report here the accumulation and transepithelial transport of Rox using the human colon-derived adenocarcinoma cell line (Caco-2) model. The cellular accumulation and transepithelial passage of Rox in Caco-2 cells were evaluated and compared to those of arsenobetaine (AsB), arsenite (AsIII), and arsenate (AsV). When Caco-2 cells were exposed to 3 μM Rox, AsB, and AsIII separately for 24 h, the maximum accumulation was reached at 12 h. After 24-h exposure, the accumulated Rox was 6–20 times less than AsB and AsIII. The permeability of Rox from the apical to basolateral side of Caco-2 monolayers was similar to AsV but less than AsIII and AsB. The results of lower bioavailability of Rox are consistent with previous observations of relatively lower amounts of Rox retained in the breast meat of Rox-fed chickens. These data provide useful information for assessing human exposure to and intestinal bioavailability of Roxarsone
Christian Burri - One of the best experts on this subject based on the ideXlab platform.
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investigations of the metabolites of the trypanocidal drug melarsoprol
Clinical Pharmacology & Therapeutics, 2000Co-Authors: Jennifer Keiser, Örjan Ericsson, Christian BurriAbstract:Background Melarsoprol remains the first-choice drug for trypanosomiasis (human African sleeping sickness). To contribute to the sparse pharmacologic data and to better understand the cause of the frequent serious adverse reactions, we investigated the metabolism of this 50–year-old Organoarsenic Compound. Results The half-life of melarsoprol determined by HPLC was <1 hour compared with 35 hours determined by bioassay and atomic absorption spectroscopy, indicating the existence of active metabolites. One metabolite, melarsen oxide, was identified by ultraviolet HPLC after incubation of melarsoprol with microsomes. The maximum plasma concentration of melarsenoxide was reached 15 minutes after administration; the clearance was 21.5 mL/min/kg and the half-life of free melarsen oxide was 3.9 hours. Either melarsen oxide or a yet-undiscovered active metabolite is irreversibly bound to proteins, as shown by ultrafiltration, precipitation experiments, and atomic absorption spectroscopy. Because of the poor pharmaceutical properties of melarsoprol, the therapeutic potential of melarsen oxide was investigated. In a rodent model of acute infection, 20 of 20 mice were cured (0.1 to 1 mg/kg intravenously or 2.2 mg/kg intraperitoneally). In a rodent model of central nervous system infection, five of six mice survived for more than 180 days (5 mg/kg intravenously), indicating a sufficient melarsen oxide penetration across the blood-brain barrier. Conclusion The prospects for the future of trypanosomiasis treatment are deplorable. Investigations on the improvement of the use of the old drugs are therefore required. The results of this study may build a basis for further research on the cause of severe adverse reactions. Clinical Pharmacology & Therapeutics (2000) 67, 478–488; doi: 10.1067/mcp.2000.105990
Kevin A. Francesconi - One of the best experts on this subject based on the ideXlab platform.
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determination of the trypanocidal drug melarsoprol and its conversion products in biological fluids with hplc icpms esms
Talanta, 2013Co-Authors: Georg Raber, Thomas Raber, Reingard Raml, Manuela Murko, Christoph Magnes, Kevin A. FrancesconiAbstract:Abstract Although melarsoprol, an Organoarsenic Compound, is widely used for the treatment of trypanosomiasis (human African sleeping sickness), very little is known about its fate in the human body, its active metabolites passing the blood–brain barrier and the mode of action. Previous pharmacological studies based on the determination of melarsoprol by HPLC–UV or by a bioassay method produced different results. We report a HPLC–ICPMS method suitable for determining melarsoprol and its metabolites in biological fluids. The arsenic selective capability of the method allowed the quantitative measurement of melarsoprol and two arsenic-containing conversion products produced when melarsoprol was incubated with human serum and blood. The major product was identified as melarsen [4-[(4,6-diamino-1,3,5-triazin-2-yl)amino]phenyl]arsonic acid by HPLC/electrospray MS, and by accurate mass measurements. Investigations about the stability of melarsoprol in serum showed that within 30 h about 10% of melarsoprol is converted to melarsen. In blood, however, most of the melarsoprol was bound to proteins and only 1% was converted to melarsen after 30 hours. The limit of detection for melarsoprol and its conversion products were in the range of 1 µg As L −1 (13 nmol As L −1 ) based on signal to noise ratio of 3 with a 10 µL injection volume allowing direct determination of the Compounds in blood and serum (after protein precipitation) at therapeutically realistic concentrations.
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arsenic species in seafood origin and human health implications
Pure and Applied Chemistry, 2010Co-Authors: Kevin A. FrancesconiAbstract:The presence of arsenic in marine samples was first reported over 100 years ago, and shortly thereafter it was shown that common seafood such as fish, crustaceans, and mol- luscs contained arsenic at exceedingly high concentrations. It was noted at the time that this seafood arsenic was probably present as an organically bound species because the concen- trations were so high that if the arsenic had been present as an inorganic species it would cer- tainly have been toxic to the humans consuming seafood. Investigations in the late 1970s identified the major form of seafood arsenic as arsenobetaine ((CH 3 ) 3 As + CH 2 COO - ), a harmless Organoarsenic Compound which, following ingestion by humans, is rapidly excreted in the urine. Since that work, however, over 50 additional arsenic species have been identi- fied in marine organisms, including many important food products. For most of these arsenic Compounds, the human toxicology remains unknown. The current status of arsenic in seafood will be discussed in terms of the possible origin of these Compounds and the implications of their presence in our foods.