Recent results of antibiotics research.
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Anti-Bacterial Agents↗
Biomedical subjects
C Tamm
Publications and source records attributed to C Tamm.
[Identification of the steroids described as "6-beta, 15-alpha-dihydroxyprogesterone", "11-alpha, 15-beta-dihydroxyprogesterone" and "12-beta, 15-beta-dihydroxyprogesterone" with 12-beta, 15-alpha-dihydroxyprogesterone].
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Chemical Phenomena↗
Effect of magnesium administered during postischemic reperfusion on myocardial oxidative metabolism in isolated rat hearts.
To determine the effect of magnesium on myocardial function and oxidative metabolism after reperfusion, isolated rat hearts perfused retrogradely with erythrocyte-enriched medium (0.4 mM palmitate bound to 0.4 mM albumin, 11 mM glucose) were subjected to 60 minutes of no-flow ischemia followed by 60 minutes of reperfusion. Untreated postischemic hearts exhibited after 15 minutes of reperfusion recovery of myocardial oxygen consumption to 65% of the preischemic value despite persistent depression of left ventricular isovolumic pressure development to 21%. Magnesium (15 mM) administered during the initial 30 minutes of reperfusion reduced myocardial oxygen consumption of reperfuse myocardium by 35%. Oxidation of [1-14C]palmitate was slightly more reduced (-55%) than oxidation of [U-14C]glucose (-42%). Magnesium did not influence ultimate recovery of contractile function and cumulative myocardial release of creatine kinase. Thus, 15 mM magnesium administered during reperfusion elicited a reduction of oxidative metabolism. However, magnesium did not modify myocardial injury.
Animals↗
Biosynthesis of cytochalasans. XI. New results on the incorporation of phenylalanine into cytochalasin D by Zygosporium masonii [1].
Incorporation of L-[2-2H]phenyl-[2-2H]alanine and L-phenyl-[2-13C, 15N]alanine into cytochalasin D by Zygosporium masonii involved the complete loss of both the alpha-2H- and the alpha-15N-atom. Incorporation of a mixture of L-phenyl-[15N]alanine and L-[U-14C]phenylalanine into cytochalasin D and protein amino acids (phenylalanine, leucine, isoleucine) was accompanied by a substantial loss of 15N with respect to 14C. These effects are attributed to rapid exchange reactions taking place while L-phenylalanine is part of the intracellular pool of amino acids. In addition, the medium- and concentration-dependent incorporation of the carbon skeleton of exogeneous D-phenylalanine into cytochalasin D is reported. In a peptone-based complex medium, D-phenyl-alanine is poorly incorporated. Throughout the whole concentration range (0-250 mg/l), the incorporation rates are less than 10% of those of L-phenylalanine. In a minimal medium containing NH4NO3 as nitrogen source however, D-phenylalanine is preferred over the natural enantiomer by a factor of 1.28 up to 6.78, depending on the concentrations of exogeneous D- and L-phenylalanine. These effects are attributed to the medium-dependent activities of different amino acid transport systems responsible for the uptake of D- and L-phenylalanine in Z. masonii.
Cytochalasin D↗