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Biomedical subjects

B M Tolbert

Publications and source records attributed to B M Tolbert.

At least 19 recordsLinked to original sources
PubMed1987

Brain ascorbate depletion as a response to stress.

Ascorbate-depleted rainbow trout were fed a single dose of L-1-14C-ascorbic acid, then held in metabolism chambers for four consecutive five-day periods. Tissue samples were analyzed for 14C, ascorbate, and ascorbate-2-sulfate. Brain ascorbate showed a long turnover time following a very slow uptake. The loss of brain ascorbate after five days in metabolism chambers was highly significant (p less than 0.001) when compared with similar dosed fish not chambered. A brain ascorbate pool which does not exchange with the body pool is proposed. Possible mechanisms are discussed and a kinetic model is suggested.

Animals↗
PubMed1975

Metabolism of ascorbic acid and ascorbic-2-sulfate in man and the subhuman primate.

Man does not catabolize ascorbate to CO2, whereas the monkey does catabolize ascorbate and ascorbate sulfate to CO2 when these compounds are given orally. However, it takes the same length of time to produce frank scurvy in both man and the monkey, thus indicating that the comparative storage, rate of use, and mode of metabolism of ascorbate is similar in both species. Preliminary feeding and isotope studies conducted on monkeys are in agreement with the fact that only a small amount of labeled ascorbate or ascorbate sulfate equilibrated with body stores. These results are in agreement with published ascorbic acid requirements of 10 mg/kg body weight. In our experiments, 250 mg/day had to be fed to a 10-kg monkey to completely clear all signs of scurvy and return blood ascorbate levels to normal. Ascorbic acid administered intravenously to monkeys appears to equilibrate completely with the ascorbate pool(s). Ascorbate sulfate was found to be a urinary metabolite of both ascorbic-1-14C acid and ascorbic-6-14C acid fed orally to monkeys.

Animals↗
PubMed1971

Ascorbate sulfate: a urinary metabolite of ascorbic acid in man.

Ascorbate-3-sulfate is a significant metabolite of ascorbic acid excreted in human urine. The characteristics of this compound were determined in experiments in which labeling with carbon-14 and tritium was used coupled with cochromatography with synthetic ascorbate-3-sulfate (both labeled and not labeled with sulfur-35) in a variety of solvent and absorbent systems.

Ascorbic Acid↗