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Biomedical subjects

R Chahine

Publications and source records attributed to R Chahine.

42 records · Page 3Linked to original sources
PubMed1987

Taurine and icosanoids in the heart.

Experiments were carried out on non-working isolated rabbit hearts perfused by Tyrode solution: the effects of Taurine introduced into the coronary circulation were studied on the biosynthesis of the anti-thromboxane synthetase factor ("FATS") and on the TXA2 and PGI2 synthetase activities of cardiac tissue. The effects of Taurine were simultaneously studied on the biosynthesis of TXA2 and PGI2 in vitro. Experiments performed under the adopted conditions have shown that in vitro Taurine did not significantly modify the biosynthesis of TXA2 and PGI2; ex vivo Taurine did not change the biosynthesis of "FATS" but inhibited both TXA2 and PGI2 synthetase activities of the cardiac tissue: Taurine was more active on the TXA2 synthetase activity than on the PGI2 one. Thus Taurine promoted the formation of vasodilator and antiaggregating PGI2 at the expenses of vasoconstrictor and proaggregating TXA2. This could at least partly explain the beneficial effects of Taurine in the physiopathology of the heart.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Comparative effects of total flavonoids extracted from Ribes nigrum leaves, rutin and isoquercitrin on biosynthesis and release of prostaglandins in the ex vivo rabbit heart.

Experiments were carried out on isolated rabbit hearts: PG biosynthesis was induced by administration into the coronary circulation of a single dose of arachidonic acid (100 micrograms) and the PGs synthesized and released in the heart effluent were detected by bioassays. Total flavonoids (TF) extracted from Ribes nigrum leaves and their 2 major components, rutin and isoquercitrin had neither spasmodic nor relaxing activity on rat stomach strip. They were not capable of inducing any biosynthesis and release of PG-like substances and did not act on PGE2 receptors. They inhibited both biosynthesis and release of PG-like substances: TF were more active than rutin and isoquercitrin: ID30 was 1.03 +/- 0.24 mg/ml for TF versus 3.75 +/- 0.24 mg/ml and 2.31 +/- 1.4 mg/ml for rutin and isoquercitrin respectively.

Animals↗
PubMed1986

Culture-negative endocarditis with purpura and arterial emboli.

We have presented a case of culture-negative endocarditis in which purpura and arterial emboli were the major findings, and in which echocardiograms were normal, but angiograms revealed vegetations and unsuspected severe aortic valve insufficiency.

Aortic Valve Insufficiency↗
PubMed1982

Hemodynamic and metabolic effects of prostacyclin after coronary bypass surgery.

The hemodynamic and metabolic effects of prostacyclin (PGI2) were assessed in 12 patients who underwent coronary bypass surgery. PGI2 were injected intravenously at a rate of 2.5 ng/kg/min for 10 minutes, followed by three consecutive 10-minute injections of 5, 10 and 20 ng/kg/min. PGI2 infusion decreased systolic and diastolic arterial pressures by 17% (p less than 0.001) and increased cardiac index by 17% (p less than 0.001) without changing the heart rate. Right atrial, pulmonary arterial and pulmonary wedge pressures remained essentially unchanged. Total vascular resistance decreased by 37% (p less than 0.001). Rate-pressure product, an index of myocardial oxygen consumption, decreased by 13% (p less than 0.01), while stroke work index did not change. A 36% decrease in arterial PO2 (p less than 0.001) was the most consistent metabolic effect induced by PGI2 infusion. However, oxygen transport increased by 11% (p less than 0.05), suggesting that no decrease in peripheral oxygen supply was produced. Thus, PGI2 improved cardiac function and performance by a predominant effect on total vascular resistance. It may be valuable in the management of patients who undergo coronary artery surgery.

Adult↗
PubMedDate not supplied

[Cardiovascular risk factors: smoking in the context of recent events in Lebanon].

Epidemiological studies have demonstrated that cigarette smoking increases the incidence of myocardial infarction and sudden death. Psychological and physical stress, like smoking, activates the sympathetic adrenal medullary and pituitary-adrenal cortical systems. We therefore thought that the effects of stress and smoking together might increase the risk of cardiovascular disease. The seventeen-year Lebanese war was a source of real psychological stress. It was a very traumatic time for many citizens, forced to cope with the situation and its tragic consequences. We evaluated the effects of smoking and traumatic experiences during war using a study population of 46 Lebanese men aged between 28 and 45. We determined hemodynamic characteristics, such as heart rate and arterial blood pressure, and plasma indicators (cortisol and thromboxane concentrations). We found that smoking itself significantly increased all of these variables. The increase was larger, but not significantly so, in smokers who had experienced traumatic events during the war. This study suggests that preventive efforts should be directed at those groups with combinations of risk factors (e.g. smoking and stress) rather than at groups with one risk factor only. Accurate assessment of risk factors, their predictive value and their interactions are vital for any program of preventive measures.

Adult↗