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Biomedical subjects

U Weiss

Publications and source records attributed to U Weiss.

At least 91 records · Page 5Linked to original sources
PubMed1983

Effects of diltiazem on vulnerability to atrial and ventricular reentrant arrhythmias in the normal and ischemic heart.

In experiments on 20 artificially ventilated anaesthetized dogs, the effects of the new calcium antagonist diltiazem on the stimulation thresholds to repetitive extrasystoles and fibrillation of the atria and the ventricles, respectively, and on ventricular dysrhythmias 6-24 h after acute coronary occlusion were investigated. The electrophysiological studies were performed using different methods of programmed stimulation of the heart. The results show that therapeutic doses of diltiazem provide no protection against stimulus-induced supraventricular reentrant arrhythmias with the AV-node not involved in the reentrant circus, and have no antifibrillatory efficacy in electrically induced ventricular arrhythmias in the non-ischemic heart. In acute myocardial infarction there is no antiarrhythmic effect either. Our results can be explained by the fact that diltiazem is a specific calcium antagonist and that the slow response plays only a minor role in the arrhythmias investigated.

Animals↗
PubMed1982

The chemistry of the antibiotics chrysomycin A and B. Antitumor activity of chrysomycin A.

The yellow antibiotic chrysomycin, isolated in crystalline form in 1955, is found to consist of two closely related components, a major one, chrysomycin A, and a minor one, chrysomycin B. They differ only through the replacement of a vinyl group of chrysomycin A by methyl in chrysomycin B. The absorption spectrum of chrysomycin A is identical with that of the antitumor antibiotic toromycin (gilvocarcin V, 2064A), while that of chrysomycin B is similarly identical with the one of gilvocarcin M (2064B). The structures of these antibiotics (toromycin, the glivocarcins, and 2064A and B) have been elucidated recently. Chrysomycins A and B thus contain the same chromophores as gilvocarcins V and M, respectively; comparison of 1H and 13C NMR spectra confirms this identity. The chrysomycins differ from these other antibiotics in the C-glycosidic side-chain, which is a methylpentose in the gilvocarcins, a 3,5-dimethylpentose in the chrysomycins. Structure and relative configuration of the latter are given. The biological activity and possible biosynthesis of the chrysomycins are discussed.

Aminoglycosides↗
PubMed1981

Preparation and physiological properties of alkyl esters of 2,3-dihydroxypropionic acid.

In order to investigate the physiological behavior of alkyl esters of 2,3-dihydroxypropionic acid two such compounds have been synthesized. One of them, the 1-dodecylester of 2,3-ditetradecyloxypropionic acid was subjected to digestion by pancreatic lipase. The substance remained unaffected. For an in vivo experiment a doubly labelled homolog, the [1'-14C]decyl ester of 2,3-di[1'-3H]hexadecyloxypropionic acid was synthesized. This compound was fed by stomach tube to three groups of male albino rats. The experimental animals were killed after 2,4 and 6 h, those of the control groups after 6 h. Blood, urine, small intestines and livers were examined for radioactivity. From the recovery rates it could be derived that the molecule had been metabolized and absorbed. Obviously, the alkyl chain labelled with 14C was split off first and the alkyl chains labelled with 3H were split off thereafter. As the substance is metabolized in vivo it cannot be utilized as a 'non-fattening fat'.

Animals↗
PubMed1980

Ro 13-9904/001, a novel potent and long-acting parenteral cephalosporin.

Ro 13-9904/001 is a novel parenteral cephalosporin antibiotic with potent in vitro activity against a wide range of beta-lactamase-producing and non-producing pathogens. In addition, Ro 13-9904/001 proved to possess a very long plasma half-life and, as a consequence, high prophylactic in vivo effectiveness.

Animals↗