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Biomedical subjects

R Löser

Publications and source records attributed to R Löser.

At least 37 records · Page 2Linked to original sources
PubMed1982

Mode of action of terbufibrol (INN) a hypolipidemic agent on rat liver sterol synthesis.

In an in vitro assay, rat liver cholesterol synthesis from acetate (14C-labelled) was inhibited by the hypolipidemic compound Terbufibrol (6, 11). In contrast to this, Terbufibrol in the same concentration showed hardly any effect on cholesterol synthesis with HMG-CoA (3-hydroxy-3-methylglutaryl-CoA) and mevalonate as precursors. However, liver cytosols of rats pretreated with Terbufibrol (100 mg/kg), showed in vitro double cholesterol synthesis with the precursors acetate and HMG-CoA and practically no effect with mevalonate compared to controls. This stimulating effect of Terbufibrol on sterol synthesis was observed during the basal period as well as at the maximum during the diurnal rhythm of that metabolic pathway. With the help of inhibitors of protein (Cycloheximide) and RNA (Actinomycin D) synthesis it was shown that the stimulating effect of Terbufibrol on liver cholesterol synthesis was dependent on de novo protein synthesis. Further it was observed that the hepatic cholesterol 7 alpha-hydroxylase reaction was inhibited in a dose related fashion after pretreatment with Terbufibrol. From our results it was concluded that Terbufibrol blocks the hepatic cholesterol synthesis in a step between acetate and HMG-CoA.

Animals↗
PubMed1981

[Long-term results of coronary revascularization--clinical, angiographic and hemodynamic findings (author's transl)].

Clinical angiographic, and hemodynamic examinations were performed in 37 patients (mean age 54 +/- 6.5 years) with coronary heart disease 5.4 +/- 5.3 months and 57.0 +/- 15.3 months after coronary revascularisation. The results were compared with those of a preoperatively performed examination (8.1 +/- 5.9 months). Early postoperatively 57 per cent of the patients were free of angina and 32 per cent had marked relief, whereas preoperatively 73 per cent had severe angina (class III and class IV). Late postoperatively 51 per cent had no angina and 49 per cent had only slight or moderate angina. The patency rate of the aorto-coronary bypass grafts was 90 percent early and 83 per cent late postoperatively. Occlusions of the native coronary arteries proximal to the anastomosis were found in 26 per cent preoperatively, in 55 per cent early and in 84 per cent late postoperatively. The parameters of left ventricular function showed no significant alterations early and late postoperatively. The results demonstrate that the relief of angina, the patency rate of the aorto-coronary bypass grafts and the resting function of the left ventricle are approximately unchanged five years after coronary revascularisation.

Adult↗
PubMed1978

Pharmacological alterations of coronary collateral circulation; implication to the steal-phenomenon.

Measurements of resistances were performed on different parts of coronary vessels, including spontaneous collaterals in anesthetized dogs, following ligation and embolization of the descending branch of the left coronary artery. The normal situation was compared with the state of maximal pharmacological dilatation. The pharmacological dilatation decreased the collateral resistance by 24% in spite of the fact that the collaterals supplied an infarcted area in this case; the precollateral resistance, which chiefly consists of large vessels was also diminished. The collateral perfusion pressure is not only dependent on the aortic pressure, but also on the flow rate in the corresponding large coronary vessel and thereby on the ratio of precollateral to postcollateal resistance. A decrease of the collateral perfusion pressure causes an insufficient perfusion of the area supplied by the collaterals only when the pressure fall is not compensated for by an adequate decrease in the collateral resistance and when the ratio of the collateral to the nutritive resistance increases. Thus, both, the extent of the pressure fall across the precollateral resistance and the dilating capacity of the collaterals determine whether is not a pharmacological dilatation of the coronary vascular bed results in an insufficient supply of an infarcted area, i.e. in a so called "Steal-phenomenon". The results show further, that the given physical model of the microcirculation satisfactorily approximates the observed behaviour of the vascular system.

Animals↗
PubMed1976

Anoxidative work and metabolism of isolated perfused rat hearts as influenced by artificially increased heart rate.

Under anoxidative conditions the capacity of mechanical activity and the metabolism of isolated rat hearts were studied at various pacemaker-induced heart rates. Isovolumic work decreased to about one third of its initial rate within a 5 min period of anoxidative perfusion and remained almost constant during a further 10 min observation time. Increased heart rate (100, 175, and 250 b.p.m.) was associated with an increase in left ventricular diastolic pressure and with decreases in systolic pressure and maximal dp/dt. Lactate production, tissue creatine phosphate and inorganic phosphate had no consistent relationship to heart rate, whereas tissue ATP decreased with increasing heart rate. It is concluded that the rate of anoxidative isovolumic work cannot be increased by raising the heart rate since anoxidative carbohydrate breakdown cannot be more activated than at the lowest heart rate studied and cannot be more activated than at the lowest heart rate studied and cannot exceed a rate of 30 mumol hexose/min-g dry weight in the perfused heart.

Animals↗
PubMed1975

The inhibition of bacterial growth by ochratoxin A.

A series of bacterial species was examined for their sensitivity to ochratoxin A. Only grampositive bacteria could be inhibited, generally at a pH lower than 7.0. Bacillus subtilis did not show any reduction of growth rates in presence of ochratoxin A, but had a prolonged lag phase. With Staphylococcus pyogenes var. aureus and Streptococcus faecalis, a prolonged lag phase and a reduction of the growth rate was observed. Most sensitive was Streptococcus faecalis in the exponential-growth phase. The inhibition could be diminished by changing the pH to neutral, or by addition of yeast extract, tetrahydrofolate, or MgSO4. With MgSO4 a complete abolition of the inhibitory effect was achieved, but not with CaCl2. During growth inhibition, protein and RNA synthesis were reduced simultaneously, but not DNA synthesis. Even with the very high concentration of 1 mg/ml, no lethal effect was observed.

Aspergillus↗
PubMed1975

Free-flow electrophoresis. II. Analysis of the method with respect to preparative cell separation.

Electrophoretic cell separation by means of free-flow electrophoresis in an FF5 apparatus was investigated with respect to band resolution, separation capacity, reproducibility and influence on cell viability. Very sharp bands and a large separation capacity were achieved using triethanolamine/acetate buffered glycine media as liquid curtain. Acid buffer ions such as N-2-hydroxyethylpiperazine-N'-ethanesulfonic acid (HEPES) or phosphate produced broader bands. Osmotic expanders such as saccharides, though preserving cell viability excellently, decrease electrophoretic velocity and thus separation capacity. The decrease in cell viability observed in glycine media could be compensated for by addition of Ca2. Band broadening caused by methodologically specific velocity flow profiles could be reduced to a negligible level by coating the chamber walls with albumin and by appropriate adjustment of sample flow rate and liquid curtain velocity. Under the optimum conditions described, selective cell loss and artificial change in electrophoretic mobility of the cells during operation can be disregarded. The main reason for cell loss was cell aggregation at low ionic strength, which can be prevented or reversed by treatment of the cells with deoxyribonuclease.

Animals↗