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Biomedical subjects

C R Jansen

Publications and source records attributed to C R Jansen.

At least 19 recordsLinked to original sources
PubMed1977

Effect of vitamin or amino acid supplementation on plasma free amino acid levels in South African Blacks.

The object of this study was to determine the effect of large oral doses of L-leucine, vitamin B1, vitamin B2, vitamin B6 or vitamin C, given over a period of days, on the plasma free amino acid levels and protein nutrition index values of South African Blacks on a maize diet. In addition, single loads of L-tryptophan or L-kynurenine were given before and after the above regimen of L-leucine or vitamin to determine the effect of tryptophan or kynurenine with and without the influence of these factors on the plasma free amino acid levels and protein nutrition index values. Vitamin C therapy or a single dose of L-tryptophan increased the total plasma free amino acid levels. L-leucine therapy or a single loading dose of L-tryptophan increased the protein nutrition index. Single loading doses of L-kynurenine decreased the protein nutrition index. The levels of non-essential amino acids in the plasma of Blacks were much higher than those of Whites, and consequently the protein nutrition index values were much lower.

Black or African American↗
PubMed1977

Metabolism of 14C-labelled L-tryptophan, L-kynurenine and hydroxy-L-kynurenine in miners with scleroderma.

Six South African White miners were studied with the 2-g L-tryptophan load test and tracer doses of L-tryptophan-7a-14C, L-kynurenine-keto-14C and hydroxy-L-kynurenine-keto-14C. The breath 14CO2 and 14 urinary metabolities were measured. When they were compared with a previous study of American women with scleroderma, similar 14CO2 and tryptophan metabolite excretion patterns were observed in the data from the miners. The labelled quinolinic acid excretion was more significantly elevated in the South African miners' urine than in the urine of the American women. The data from both studies suggest that some patients with scleroderma have an altered step in the tryptophan metabolic pathway after hydroxy-anthranilic acid. What relationship exists between the induction of pulmonary silicosis and the subsequent development of scleroderma, requires additional human studies.

Carbon Dioxide↗