[Arteriosclerosis. II. Pathogenesis of dyslipoproteinemia].
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Biomedical subjects
Publications and source records attributed to B Cybulska.
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The aromatic heptaene vacidin A induces ion selective channels in human red blood cells. The ion flux induced leads to a secondary effect--colloid osmotic haemolysis. Molecular variations at ionizable polar groups of the antibiotic modify the properties of the permeability pathway concerning intercationic selectivity and the symmetry of ion flux.
Natural aromatic heptaene macrolide antibiotics and their N-acyl and methyl ester derivatives, which differ mainly in their electric net charge, were compared for their efficiency in inducing yeast growth inhibition, red blood cell lysis, and increase in the ionic permeability of large unilamellar lipidic vesicles. Antifungal activity was found to decrease in the following order: neutral congruent to positively charged greater than negatively charged compounds. Hemolytic activity decreased in the order: neutral greater than negatively charged much greater than positively charged compounds. On lipidic model membranes, themselves either positively or negatively charged, electrostatic interaction was shown to have practically no influence on the efficiency of the differently charged antibiotics. On both biological and model systems, positively charged antibiotics consistently were found to be more active on ergosterol-containing than on cholesterol-containing membranes, and were therefore considered as potentially good candidates for specific antifungal agents.
Twenty two patients with hyperlipoproteinaemia type IV consumed fructose in a daily dose of 80 g for 28 days. Apart from that they kept their normal diet. We observed the considerable heterogeneity of hyperlipaemic responses of patients under study after 7 days of fructose feeding. However VLDL-TG and the relative ratio apo CIII1/apo CII in VLDL increased in the whole group. The rise in serum VLDL was associated with a fall in LDL-Chol and HDL-Chol. After extention of fructose intake to 28 days a decrease of VLDL-TG with concomitant fall of the relative ratio apo CIII1/apo CII in VLDL was found. LDL-Chol increased. Our observations point to the reversibility of fructose-induced changes in the lipoprotein composition after prolongation of its intake.
The efficiency in inducing cation permeability of vacidin A, candicidin D and amphotericin B has been compared on small and large lipidic vesicles. Amphotericin B is two times less effective on large than on small vesicles. On the contrary, vacidin A and candicidin D are about ten times more effective on large than on small vesicles. These data are consonant with what is observed on living cells.
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The cationic permeability induced by two aromatic heptaenes, vacidin A and candicidin D, has been studied on egg yolk L-alpha-phosphatidylcholine single walled vesicles as a function of cholesterol and ergosterol concentration. For comparison amphotericin B and nystatin were also tested. Vacidin A and candicidin D elicit cation permeability in both types of vesicles in the same concentration ranges and exhibit only quantitative differences in cholesterol and ergosterol vesicles. The active concentration range is of the same order of magnitude as the active concentration range of amphotericin B, at variance with what is obtained on biological cells. This difference is interpreted in term of mechanism of action of polyene on both biological and model membranes.
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