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C T Bishop

Publications and source records attributed to C T Bishop.

At least 19 recordsLinked to original sources
PubMed1997

Electrospray analysis of biological samples for trace amounts of trichloroacetic acid, dichloroacetic acid, and monochloroacetic acid.

Trichloroethylene (TCE) has been identified as a widespread groundwater contaminant. Trichloroacetic acid (TCA) and dichloroacetic acid (DCA) are toxicologically relevant metabolites of TCE that produce tumors in B6C3F1 mice. A sensitive method for measuring these metabolites in plasma has been developed to obtain pharmacokinetic data from TCE exposure. This is particularly important because DCA is more potent at producing hepatoproliferative lesions than TCA. At present, it is unclear whether DCA is produced by humans. Existing gas chromatographic methods cannot detect DCA at low nanogram-per-milliliter levels. A Finnigan TSQ 700 mass spectrometer (MS) with electrospray ionization was used to measure TCA, DCA, and monochloroacetic acid (MCA) in plasma. The MS was operated in negative ion tandem MS mode. The limit of detection for TCA and DCA was 4 ng/ml, and the limit of detection for MCA was 25 ng/mL. Plasma samples from human subjects exposed to 100 ppm TCE for 4 h contained TCA at concentrations as high as 10 micrograms/mL. DCA concentrations were less than 5 ng/mL, and MCA was not detected (less than 25 ng/mL).

Acetates↗
PubMed1985

Free radical damage to cultured porcine aortic endothelial cells and lung fibroblasts: modulation by culture conditions.

Culture conditions modulating cell damage from xanthine plus xanthine oxidase-derived partially reduced oxygen species were studied. Porcine thoracic aorta endothelial cells and porcine lung fibroblasts were maintained in monolayer culture. Cells were prelabeled with 51Cr before xanthine plus xanthine oxidase exposure. Endothelial cells showed 30 to 100% more lysis than fibroblasts and thus seemed more sensitive to this oxidant stress. The effect of cell culture age, as indicated by population doubling level (PDL), was examined. Response of low PDL endothelial cells and fibroblasts subjected to oxidant stress was compared with the response of PDL 15 cells. Both low PDL endothelial cells and fibroblasts responded differently to the lytic effect of xanthine oxidase-derived free radicals than did higher PDL cells. Specific activities of the antioxidant enzymes catalase, manganese superoxide dismutase, copper-zinc superoxide dismutase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase were measured in both low and high PDL fibroblasts and endothelial cells. Antioxidant enzyme specific activities could only partially explain the differences in response to oxidant stress between fibroblasts and endothelial cells and between low and high PDL cells. Cell culture medium composition modulated the rate of production, and relative proportions of xanthine plus xanthine oxidase-derived partially reduced species of oxygen, i.e. superoxide, hydrogen peroxide, and hydroxyl radical. Serum content of medium was important in modulating free radical generation; superoxide production rates decreased 32%, H2O2 became undetectable, and hydroxyl radical generation decreased 54% in the presence of 10% serum. The medium protein and iron content also modulated free radical generation. The data suggest that cell culture media constituents, cell type, and cell culture age greatly affect in vitro response of cells subjected to oxidant stress.

Animals↗
PubMed1982

Familial effects on plasma sex-steroid content in man: testosterone, estradiol and Sex-hormone-binding globulin.

We investigated whether familial factors influence the plasma content of sex-steroids and sex-hormone-binding globulin (SHBG) in 98 adult males of 66 families. They had no apparent endocrine dysfunction, The 0800-1100 hr plasma levels of testosterone, 5 alpha-dihydrotestosterone (DHT), estradiol-17 beta (E2) and estrone (E1) were measured by radioimmunoassay. The free fractions of E2 and testosterone were determined by equilibrium dialysis, and binding capacity of SHBG was also calculated. The data were analyzed by analysis of variance. We observed that the differences in the plasma content of testosterone (p = .02). SHBG binding capacity (p = 0.1), and E2 (p = 0.3), free E2 index (p = .05) were all substantially less variable within groups of brothers than among non-brothers. The variability of the plasma concentration of DHT, free testosterone and E1 was not significantly less within brothers than among non-brothers. The correlation between either plasma testosterone content (r = .14) or SHBG binding capacity (r = .12) and percent of ideal body weight was not significant statistically. Age had no effect on the results. Our data suggest that genetic and/or environmental factors may affect the plasma content of testosterone, E2 and SHBG binding capacity.

Adult↗
PubMed1977

The preparation of carbohydrate-protein conjugates: cyanuric trichloride coupling of 2-aminoethyl glycosides, and mixed-anhydride coupling of 8-carboxyoctyl glycosides to bovine serum albumin.

Preparation of the following glycosides is described: 2-aminoethyl beta-D-glycosides of (A) 2-acetamido-3,4,6-trio-O-acetyl-2-deoxy-D-glucopyranose, (B) 2-acetamido-4-O-(2-acetamido-3,4,6-trio-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-3,6-di-O-acetyl-2-deoxy-beta-D-glucopyranose (N,N'-diacetylchitobiose pentaacetate), (C) 4-O-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-2,3,6-trio-O-acetyl-beta-D-glucopyranose (cellobiose heptaacetate); 8-carboxyoctyl glycosides of (D) cellobiose, and (E) N,N'-diacetylchitobiose. Conjugates were prepared from (A), (B), and (C) by coupling to bovine serum albumin by cyanuric trichloride and subsequent deacetylation; (D) and (E) were coupled to bovine serum albumin by the mixed-anhydride reaction. Conjugates (A) and (B) were insoluble; conjugates (C), (D), and (E) functioned as artificial antigens and gave rise to precipitating antibodies in rabbits. Specificities of the antisera were determined by inhibition studies.

Antibodies↗