نتایج جستجو برای: polychlorinated biphenyl pcb
تعداد نتایج: 12350 فیلتر نتایج به سال:
BACKGROUND Few data are available on polychlorinated biphenyl (PCB) concentrations over critical windows of human reproduction and development inclusive of the periconception window. OBJECTIVES Our goal was to measure changes in PCB concentrations from preconception to pregnancy, through pregnancy, or after a year without becoming pregnant. METHODS Seventy-nine women planning pregnancies we...
BACKGROUND Though commercial production of polychlorinated biphenyls was banned in the United States in 1977, exposure continues due to their environmental persistence. Several studies have examined the association between environmental polychlorinated biphenyl exposure and modulations of the secondary sex ratio, with conflicting results. OBJECTIVE Our objective was to evaluate the associatio...
Tree swallows (Tachycineta bicolor) are widely used as indicators of local polychlorinated biphenyl (PCB) contamination in North America. Although determining total PCB residues in tissues is useful in environmental monitoring, analysis of PCB congener profiles may reveal sources of contamination and thus prove to be a more refined tool to track contaminants through the food web. To show how di...
The objective in the first phase of this study was to screen alfalfa, flatpea, sericea lespedeza, deertongue, reed canarygrass, switchgrass, and tall fescue for phytoremediation of polychlorinated biphenyl (PCB)-contaminated soil. During the second phase, the focus was rhizosphere characterization to optimize PCB phytoremediation. Aroclor 1248 (PCB) was added to soil at 100 mg x kg(-1) of soil....
A gram-positive polychlorinated biphenyl (PCB) degrader, Rhodococcus sp. strain RHA1, metabolizes biphenyl through the 2-hydroxypenta-2,4-dienoate (HPD) and benzoate metabolic pathways. The HPD metabolic pathway genes, the HPD hydratase (bphE1), 4-hydroxy-2-oxovalerate aldolase (bphF1), and acetaldehyde dehydrogenase (acylating) (bphG) genes, were cloned from RHA1. The deduced amino acid sequen...
We investigated whether the threshold concentration for polychlorinated biphenyl (PCB) dechlorination may be lower in biosurfactant-amended sediments compared with biosurfactant-free samples. At PCB concentrations of 40, 60, and 120 ppm, the surfactant amendment enhanced the PCB dechlorination rate at all concentrations and the rate was also faster at higher concentrations. On a congener group ...
Cytochrome P450-catalyzed enzyme activity in cell culture was investigated as a bioassay for 2,3,7,8-tetrachlorodibenzop-dioxin (TCDD) equivalents in environmental mixtures of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and biphenyl (PCB) congeners. A problem with the use of enzyme induction is that certain congeners are unable to induce P4501A enzyme activity to the same maxi...
This Standard Reference Material (SRM) is a frozen fish tissue homogenate that was prepared from fish collected from Lake Michigan, and is intended primarily for use in evaluating analytical methods for the determination of selected trace elements, methylmercury, total mercury, polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, polybrominated diphenyl ether (PBDE) congeners, perf...
The present study examined the utility of an immunoblot method for quantitation of cytochrome P450 isozymes in archived liver samples as a bioassay of exposure to halogenated hydrocarbons. Hepatic microsomes were prepared from 44 archived polar bear (Ursus maritimus) liver homogenates that had been stored at approximately -40 degrees C for 9-10 years and analyzed on blots probed with antibodies...
To analyze the effect of polychlorinated biphenyl (PCB) 118 on fish bone metabolism, we examined osteoclastic and osteoblastic activities, as well as plasma calcium levels, in the scales of PCB (118)-injected goldfish. In addition, effect of PCB (118) on osteoclasts and osteoblasts was investigated in vitro. Immature goldfish, in which the endogenous effects of sex steroids are negligible, were...
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