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Chromium Compounds (chromium + compound)
Selected AbstractsElucidation of the percutaneous absorption of chromium compounds by functional proteomicsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 22 2009Tai-Long Pan Abstract Chromium compounds are known to be associated with cytotoxicity and carcinogenicity when applied via a skin route. The aim of this study was to evaluate the skin permeability and toxicological profiles of four chromium species. Chromium permeation across the skin, as determined by an in vitro Franz cell, decreased in the order of sodium chromate>potassium chromate>potassium dichromate>chromium nitrate. The uptake of chromium species within the skin generally showed a contrary trend to the results of permeation, although differences among the various compounds were not large. Levels of in vivo skin deposition of the four compounds showed no statistically significant differences. Potassium chromate produced the greatest disruption of the skin structure as determined by HE staining, followed in order by sodium chromate, potassium dichromate, and chromium nitrate. This indicates that hexavalent chromium elicited greater toxicity to the skin compared to trivalent chromium. A similar result was observed for the viability of skin fibroblasts. To improve our understanding of the molecular mechanisms leading to functional changes in proteins, proteomic tools, including 2-DE and MS techniques combined with sequence database correlations, were applied to identify target proteins altered by pathologic states. Eight protein spots, corresponding to cutaneous enzymes involved in energy metabolism and chaperon proteins, which were identified and discussed in this study, were associated with skin cytotoxicity, immunity, and carcinogenesis. In addition, functional proteomics of skin tissues may provide a promising tool for developing therapeutic strategies and can serve as the basis for further research. [source] Ethylene polymerization behavior of Cr(III)-containing montmorillonite: Influence of chromium compoundsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2009Kazuhiro Yamamoto Abstract Montmorillonite was treated with Cr(NO3)3, Cr(acetate)3, and Cr(acac)3 to give three catalyst precursors, Cr-MMT-1, Cr-MMT-2, and Cr-MMT-3, respectively. Application of these catalysts to the ethylene polymerization reaction revealed Cr-MMT-1 to be much more reactive than the other two while the molecular weight distributions of the polymers were practically the same. Elemental analysis, XRD, and TEM measurements suggested that chromium occupied the interlayer section in Cr-MMT-1 and mostly the outer surface region for the other two catalysts. Aluminosilicate-supported Cr catalysts exhibited reactivity similar to that of Cr-MMT-2 and Cr-MMT-3. However, more of the low-molecular-weight polymer was formed. These data suggested that there is a relationship between the sites of the Cr ions and catalytic reactivity, and between supporting solid identity and molecular weight distribution of the polymer. The use of n -Bu2Mg and Et2Zn in the place of Et3Al led to lower activity but gave polymers of narrower molecular weight distribution, with more of the high-molecular-weight material. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2272,2280, 2009 [source] Production of Chromium-Doped ,-Al2O3 Whiskers Via Vapor Liquid Solid DepositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2006Carmen Cerecedo The prime objective of this work is to demonstrate that chromium-doped alumina fibers could, for the first time, be obtained via vapor liquid solid (VLS) deposition. Various procedures are described and discussed in the text. The mechanism for effective doping is also discussed, and the resulting fibers are analyzed. A modification of the basic VLS deposition process was investigated with the aim of producing doped ,-Al2O3 (,-alumina or corundum) whiskers. Chromium-doped (ruby) corundum whiskers were obtained by the introduction of Cr3+ in gas form within the argon flow used to attain inert furnace atmospheres. Various procedures are described and discussed in the text, using different chromium compounds, and the mechanism of effective doping is also discussed in each case. [source] Elucidation of the percutaneous absorption of chromium compounds by functional proteomicsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 22 2009Tai-Long Pan Abstract Chromium compounds are known to be associated with cytotoxicity and carcinogenicity when applied via a skin route. The aim of this study was to evaluate the skin permeability and toxicological profiles of four chromium species. Chromium permeation across the skin, as determined by an in vitro Franz cell, decreased in the order of sodium chromate>potassium chromate>potassium dichromate>chromium nitrate. The uptake of chromium species within the skin generally showed a contrary trend to the results of permeation, although differences among the various compounds were not large. Levels of in vivo skin deposition of the four compounds showed no statistically significant differences. Potassium chromate produced the greatest disruption of the skin structure as determined by HE staining, followed in order by sodium chromate, potassium dichromate, and chromium nitrate. This indicates that hexavalent chromium elicited greater toxicity to the skin compared to trivalent chromium. A similar result was observed for the viability of skin fibroblasts. To improve our understanding of the molecular mechanisms leading to functional changes in proteins, proteomic tools, including 2-DE and MS techniques combined with sequence database correlations, were applied to identify target proteins altered by pathologic states. Eight protein spots, corresponding to cutaneous enzymes involved in energy metabolism and chaperon proteins, which were identified and discussed in this study, were associated with skin cytotoxicity, immunity, and carcinogenesis. In addition, functional proteomics of skin tissues may provide a promising tool for developing therapeutic strategies and can serve as the basis for further research. [source] | ||||||||||