No description available.

The biochemical basis for the unique ability of Beagle dog liver microsomes to metabolize 2,2',4,4',5,5'-hexachlorobiphenyl (245-HCB) was investigated. The major phenobarbital (PB)-inducible cytochrome P-450 isozyme, called PBD-2, was purified to 95% homogeneity from liver microsomes of both control and PB-treated dogs, as evidenced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In a reconstituted system containing cytochrome b₅, PBD-2 metabolized 245-HCB at a rate greater than three-fold that seen in liver microsomes from PB-treated dogs. Immunoblot analysis revealed that, upon PB treatment, the increase in the level of PBD-2 in dog liver microsomes correlated well with the increase in the rate of hepatic microsomal metabolism of 245-HCB by dogs. Anti-PBD-2 IgG caused a > 90% inhibition of 245-HCB metabolism by microsomes obtained from control and PB-treated dogs. Studies were also conducted to assess the ability of PBD-2 to metabolize 2,2',3,3',6,6'-hexachlorobiphenyl (236-HCB) and 4,4'-dichlorobiphenyl (4-DCB). Dog liver microsomes readily metabolized 236-HCB, and PB treatment led to a dramatic increase in this rate of metabolism, suggesting a role for PBD-2 in the metabolism of 236-HCB. In a reconstituted system containing cytochrome b₅, PBD-2 metabolized 236-HCB at a rate greater than two-fold that observed in microsomes from PB-treated dogs. Pretreatment of microsomes obtained from PB-treated dogs with chloramphenicol (a highly selective inactivator of PBD-2) caused a nearly 70% decrease in the microsomal metabolism of 236-HCB. Anti-PBD-2 IgG inhibited by > 90% 236-HCB metabolism by microsomes from both control and PB-treated dogs. In contrast, PB treatment caused no significant alteration in the metabolism of 4-DCB by dog liver microsomes, and PBD-2 metabolized this compound poorly, even in the presence of cytochrome b₅. Taken together, these data indicate that the dog hepatic cytochrome P-450 isozyme, PBD-2, is present in microsomes obtained from both control and PB-treated animals. PBD-2 is responsible for the microsomal metabolism of 245-HCB, and this isozyme likely accounts for the unique ability of Beagle dogs to readily metabolize and eliminate this compound in vivo. The data also strongly suggest that PBD-2 is responsible for the microsomal metabolism of 236-HCB in dogs. However, PBD-2 is not likely involved in the microsomal metabolism of 4-DCB by this species.

This study investigates the concentrations and characteristics of PCB congeners in aquaculture oysters (Crassostrea gigas) along the western coast of Taiwan. Oyster samples were collected from 5 aquacultural areas, Hsinchu, Changhua, Yunlin, Chiayi and Tainan, during May 2003 and March 2004. The results showed that the total PCB concentrations in the oysters were between 3.43 and 93.3 ng/g dry weight, and the median concentration was 20.3 ng/g dry weight. The highest concentrations were found in the oysters collected from Luermen (Tainan) (74.7~93.3 ng/g). Samples from other two stations of Tainan aquacultural area, Cigu and Anping, were also found relative high total PCB concentrations (46.5~72.0 ng/g) than the rest area. This indicates a local pollution source should be blamed on. Except the above areas, the total PCB concentrations were found evenly distributed throughout the coast (3.43~41.2 ng/g with a median concentration of 14.9 ng/g). The PCB concentrations were not significantly correlated with lipid contents and shell lengths. Therefore, the variation of PCB concentrations in all stations might be dependent on the presence of localized sources of contamination rather than on the lipid content and shell length variation of oysters. In some observed stations, the PCB concentrations of oysters in autumn are significantly higher than in summer. That is because the adoptive tide in winter will lead to the tendency to reduce PCB concentrations of oysters.

No description available.

For the past several decades, industry has filled lagoons and landfills with significant quantities of polychlorinated biphenyls (PCBs). Other wastes such as carbon tetrachloride and various alcohols have mixed with PCBs. Soil columns spiked with Aroclor 1242 were leached with such solvents. Ninety-one days of deionized water flow did not move a detectable amount of Aroclor 1242 more than 2 cm. through soil columns. Sixty-nine days was sufficient time for an alcohol mixture to carry Aroclor 1242 over 7 cm, the soil depth of the column. Five days was sufficient time for carbon tetrachloride: ethanol to carry Aroclor 1242 the same distance. A mixture of organic solvents can promote mobility of lipophilic organics such as polychlorinated biphenyls in the soil when water alone would not be effective. While assessing the extent of a chemical spill or the contamination resulting from improper disposal, it is clear that the interactions of chemical contaminants must be considered. / Department of Natural Resources

Thesis (M.S.)--Bowling Green State University, 2007. / Document formatted into pages; contains vii, 66 p. : ill. Includes bibliographical references.

Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 70-79).

Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains iv, 145 p. : ill. (some col.), col. map. Includes abstract. Includes bibliographical references.

Thesis (Ph.D.)--University of Central Florida, 2008. / Adviser: Cherie L. Geiger. Includes bibliographical references (p. 129-131).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 239-260).