Showing papers in "Acta vitaminologica et enzymologica in 1977"

Interaction of erythorbic acid with ascorbic acid catabolism.

Abstract: There exist altogether four stereoisomers of ascorbic acid Erythorbic acid (D-isoascorbic acid) differs in the spatial configuration at carbon 5 and has less than 5 per cent of biological vitamin C activity In guinea pigs, depending on an exogenous supply of ascorbic acid, a possible interaction of erythorbic acid with absorption, transport through the cell membranes at the tissue level, or with catabolism of ascorbic acid has been investigated After oral administration, results suggest no difference in absorption of these two compounds from the intestine, whereas uptake by the tissues was approximately four to one in favour of ascorbic acid Feeding experiments with erythorbic acid indicate the availability of ascorbic acid being diminished by 40-60% when administered together with erythorbic acid Kinetic data on the catabolism of ascorbic acid showed a significant reduction in half-life (50% of the dose excreted) of the vitamin caused by administration of erythorbic acid The results suggest the oxidative destruction of ascorbic acid in the liver being significantly accelerated Thus, ingestion of erythorbic acid interacts with newly introduced ascorbic acid by enforcing the breakdown of ascorbic acid Implications of these findings for the metabolism, availability and nutritional status of ascorbic acid in humans will be discussed

Large scale studies with vitamin C.

Abstract: The combination of a regular daily supplement of vitamin C with extra dosage at the time of illness has been shown to reduce the disability due to common colds and other winter illness, but we have seen little effect on frequency of infections, sense of (well-being), or levels of serum cholesterol. The variable results that have been obtained from some other trials of vitamin C may be due in part to variation in the initial nutritional state of the subjects, with the greatest effects to be expected where there is most room for improvement. Because of the great variation in individual susceptibility to infection large numbers of subjects are required in these trials and they must be strictly double-blind. Although we have seen no clear evidence of harmful side-effects, occasional sensitivity to large doses of vitamin C cannot be ruled out, and the withdrawal depression of blood levels could conceivably interfere with a patient's ability to handle stress.

Ascorbic acid metabolism and the clinical factors which affect tissue saturation with ascorbic acid.

Abstract: The factors which give rise to tissue desaturation of ascorbic acid are classified and discussed. Nutritional deprivation, normal physiological factors and metabolic factors, and pathophysiological factors may all give rise to acute and continuing ascorbic acid tissue desaturation while the factors continue to operate. Nutritional desaturation can easily be rectified by providing supplementary Vitamin C in adequate dosage. The other factors can only be rectified when the causative mechanism is arrested. Iatrogenic desaturation may be produced by aspirin and several other drugs. While causative factors excluding that of nutrition are operating, it is very difficult if not impossible to restore normal tissue values of ascorbic acid. In consequence side effects which arise from supplementary Vitamin C administration do not arise in these circumstances. The supplementary Vitamin C administration is defined as compensatory administration of Vitamin C. In healthy individuals administration of supplementary Vitamin C can be defined as (large doses). Such large doses may give rise to side effects. The mechanism by which ascorbic acid is involved in the inflammatory response is discussed.

beta-Glucuronidase activity in liver and spleen homogenates of mice experimentally infected with Schistosoma mansoni.

Abstract: A study on the beta-glucuronidase activity in liver and spleen homogenates of mice infected with an Egyptian strain of Schistosoma mansoni and of non infected control animals was carried out for a follow up period of four months. A decreased enzyme activity was observed in the spleen up to the 40th day after infection. From the 60th day on, the enzyme level in both liver and spleen was found above that in the control. The possible causes for such changes in enzyme activity are discussed.

Cytoenzymatic studies on the lymphocytes of peripheral blood and lymphatic nodes of rats in an experimental magnesium deficiency.

Abstract: Wistar rats kept on a magnesium deficient diet show several changes in the lymphatic organs as well as some disorders in the function of the immunological system, which appear as an impairment of cellular immunity and also as hypogammaglobulinemia. In the present experiment the level of leuco- and lymphocytosis has been studied. Furthermore, the activity of some lysosomal enzymes in blood lymphocytes, as well as the ability to incorporate labelled leucine shown by lymph nodes lymphocytes of deficient rats have been investigated. The rise in leuco- and lymphocytosis is similar to that reported by other authors. A significant rise in the activity of beta-glucuronidase as well as a considerable drop in the percentage of enzyme-negative lymphocytes have been observed as early as the first week of experiment. Tissue cultures of the lymph nodes, lymphocytes of deficient rats showed significantly lower values of labelled leucine incorporation with respect to the controls; in contrast, after phytohemagglutinin M stimulation the increase of incorporation in the lymphocytes of deficient and control rats was similar. Our findings may be indicative of some disorders in the redistribution of T and B lymphocytes in the blood and tissues of deficient rats. The observed cytochemical changes may be due to the intensification of autophagic processes in the lymphocytes that manifest a diminished ability to synthetize proteins.