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Biomedical subjects

C Campbell

Publications and source records attributed to C Campbell.

At least 289 records · Page 16Linked to original sources
PubMed1984

The Chinese hamster ovary glycosylation mutants LEC11 and LEC12 express two novel GDP-fucose:N-acetylglucosaminide 3-alpha-L-fucosyltransferase enzymes.

Evidence is presented that the GDP-fucose:N-acetyl-glucosaminide 3-alpha-L-fucosyltransferase activities of two Chinese hamster ovary glycosylation mutants, LEC11 and LEC12, are structurally distinct enzymes. The alpha(1,3)fucosyltransferase in LEC12 cell extracts binds to GDP-hexanolamine-Sepharose and is unaffected by 3 mM N-ethylmaleimide. In contrast, the alpha(1,3)fucosyltransferase activity in LEC11 cells does not bind readily to GDP-hexanolamine-Sepharose and is completely inhibited by 1 mM N-ethylmaleimide. The LEC11 and LEC12 alpha(1,3)fucosyltransferases also differ in the degree to which they are stimulated by divalent cations as well as in their abilities to fucosylate a variety of exogenous substrates. Of particular interest is the finding that the LEC11 alpha(1,3)fucosyltransferase adds fucose to certain sialylated glycoproteins, whereas the LEC12 enzyme is essentially unable to fucosylate these acceptors, although it is very active with their desialylated derivatives. The combined evidence shows that the LEC11 and LEC12 alpha(1,3)fucosyltransferase enzymes are different molecules and presumably, therefore, the products of distinct genes. In addition, neither of the enzymes appears identical to any of the previously described alpha(1,3)fucosyltransferase activities from other sources.

Animals↗
PubMed1984

Identification of a protein kinase as an intrinsic component of rat liver coated vesicles.

Purified rat liver coated vesicles phosphorylate two peptides, Mr 53 000 and Mr 51 000, in the presence of [gamma-32P]ATP. Incorporation of phosphate into these peptides is not stimulated by cAMP, Ca2+, or Ca2+ plus calmodulin and occurs principally on a threonine residue. Mild conditions that result in removal of coat proteins from coated vesicles remove most of the protein kinase activity, suggesting the enzyme(s) is (are) not an integral membrane protein. Photolabeling of coated vesicles with 8-azido-[alpha-32P]ATP results in specific labeling of only the Mr 53 000 and Mr 51 000 peptides. Preincubation with 10 mM N-ethylmaleimide inhibits kinase activity and concomitantly reduces photolabeling of the two peptides. Thus, the data are consistent with the hypothesis that protein kinase activity resides with these two coated vesicle proteins and that they are catalyzing an autophosphorylation reaction.

Adenosine Triphosphate↗
PubMed1984

Distribution of blood lead, blood cadmium, urinary cadmium, and urinary arsenic levels in employees of a copper smelter.

A cross-sectional medical examination of a copper smelter work force included determination of blood lead (Pb-B), zinc protoporphyrin (ZPP), blood cadmium (Cd-B), urinary cadmium (Cd-U), and urinary arsenic (As-U), since it was known that such metal impurities were present in the copper concentrate. A total of 776 copper smelter employees (680 active and 96 retirees and ex-employees) were examined. Another 144 men, never employed in the smelter, but who had worked in copper mines (and sometimes in gold mines) were also examined. Mean Pb-B, ZPP, Cd-B, and As-U were significantly higher in active copper smelter employees than in retirees or miners, indicating exposure and absorption in the copper smelter. Significant correlations between Pb-B and Cd-B, and Cd-U and As-U were present, confirming the common source of absorption. Although there was evidence for an increased lead absorption, this was very moderate, with practically no Pb-B levels in excess of 60 micrograms/dl. A marked effect of smoking on blood cadmium levels was present; nevertheless, for all smoking categories Cd-B levels were significantly higher in active employees, indicating the independent contribution of exposure to cadmium in the smelter. Cd-U did not exceed 10 micrograms/g creatinine, the generally accepted "critical" level for the kidney, but was higher than 2 micrograms/g creatinine, a level very rarely exceeded in the general population, in a sizable proportion of those examined. The highest Cd-U levels were found in retired copper smelter employees; age might have been a contributing factor, besides a longer duration of exposure in the smelter.

Absorption↗
PubMed1983

Prevaccination screening of medical and dental students. Should low levels of antibody to hepatitis B surface antigen preclude vaccination?

The prevalence of hepatitis B virus (HBV) markers in 484 medical and 329 dental students was studied. Three students (0.9%) were hepatitis B surface antigen (HBsAg) reactive, and 46 students (5.7%) were reactive for antibody to HBsAg (anti-HBs). There was no difference in anti-HBs frequency between medical and dental students, and the prevalence of this marker was not associated with year in school. Of the 46 reactors, eight (17%) were nonreproducible and 38 (83%) were reproducibly reactive when the same samples were reanalyzed. Of note, all nonreproducible reactors exhibited anti-HBs sample-negative control (S/N) ratios of less than 10, and none were positive for antibody to hepatitis B core antigen (anti-HBc). Nineteen (50%) of the reproducible reactors had anti-HBs S/N ratios equal to or greater than 10, and only 15 (39%) were anti-HBc positive. In view of these observations, we do not recommend HBV screening in a vaccine program for health students. Due to the frequency with which low-level anti-HBs reactors without anti-HBc are found to be nonreproducibly positive, we are concerned by the potential overinterpretation of such results before the formulation of decisions about the need for vaccination.

Hepatitis B↗