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Biomedical subjects

M Allam

Publications and source records attributed to M Allam.

24 records · Page 2Linked to original sources
PubMed1990

The inotropic effect of digoxin on an isolated rat heart in hypercapnia and (or) hypoxia.

The explanation for the increased frequency of troubles with digoxin therapy in patients with chronic pulmonary diseases is debated. The reported effects of hypoxia in vivo on myocardial levels of digoxin are contradictory, and there have been few studies on the effects of hypercapnia. In the past, it has been shown in rat myocardial tissue at rest in vitro that hypoxia decreased and hypercapnic acidosis increased the digoxin uptake. We performed a new study in vitro in an isolated beating rat heart perfused at constant flow (37 degrees C) and stimulated at a constant frequency (6 Hz). The performances were recorded with an intraventricular balloon equipped with a tip-manometer catheter. The action of digoxin was studied by recording systolic pressure (PS) and diastolic pressure (PD), the left ventricular developed pressure (LVDP = PS - PD), the (dP/dt)max, and the ratio (dP/dt)max/PS. First, the heart was perfused for 30 min with a modified Tyrode's solution perfusate aerated with carbogen (pH = 7.40; PCO2 = 37 mmHg; PO2 = 530 mmHg) (1 mmHg = 133.32 Pa). Various parameters of contractions were recorded (initial control values). Then the heart was perfused for 15 min with Tyrode's solution aerated either with a hypoxic gas mixture (pH = 7.41; PCO2 = 36 mmHg; PO2 = 122 mmHg), a hypercapnic gas mixture (pH = 7.08; PCO2 75 mmHg; PO2 = 485 mmHg), or a hypoxic-hypercapnic gas mixture (pH = 7.09; PCO2 = 73 mmHg; PO2 = 124 mmHg). Control hearts were continuously perfused with Tyrode's solution aerated with carbogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Cardiac derived neutrophil chemotactic factors; preliminary biochemical characterization.

The purpose of this study is to investigate whether isolated hearts perfused with cardioplegic solution release inflammatory mediators such as neutrophil chemotactic factors (NCF). Three conditions were tested, including: (1) perfusion of rabbit hearts with crystalloid cardioplegic solution (4 degree C) saturated with air (95% oxygen) and containing dextrose (i.e. complete system), (2) perfusion of rabbit hearts with non-oxygenated cardioplegic solution, containing dextrose (i.e. minus oxygen system), and (3) perfusion of hearts with cold cardioplegic solution saturated with air in the absence of dextrose (i.e. minus dextrose system). At various time intervals (5 min, 1, 2, 3 and 4 h) samples of circulated perfusate were removed and assayed for the presence of NCF using modified Boyden chambers. Rabbit peritoneal neutrophils were the indicator cells. The standard chemoattractant, f-Met-Leu-Phe (f-MLP) was the positive control. High levels of neutrophil chemotactic activity were detected in perfusate of all above described hearts perfused for 4 h (i.e. 194 +/- 22% of f-MLP control--complete system, 126 +/- 13%--minus oxygen and 136 +/- 10%-minus dextrose). Histological evaluation of these hearts showed evidence of global ischemia. We also detected significant levels of NCF in effluent of hearts perfused for 5 min, 1, 2 and 3 h. Similar to perfused hearts, isolated rabbit hearts incubated for 4 h with non-oxygenated cardioplegic solution (in presence and absence of dextrose) released high levels of NCF (132 +/- 18%-intact heart; and 100 +/- 6% myocardial segments). Standard checkerboard analysis revealed that the observed activity released from these hearts is chemotactic.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Effects of hypoxia and hypercapnia on atrial natriuretic factor and plasma renin activity in conscious dogs.

1. The aim of the present study was to assess the effects of hypercapnia or hypoxia on plasma concentrations of atrial natriuretic factor (ANF) in conscious unrestrained dogs. 2. For this purpose, chronically instrumented dogs were exposed in a random order to either room air, or to an atmosphere containing 21% O2/10% CO2/69% N2 to produce hypercapnia, or 10% O2/3% CO2/87% N2 to produce hypoxia without respiratory alkalosis. 3. Plasma concentrations of ANF did not change significantly during hypoxia. 4. In contrast, during hypercapnia, plasma concentrations of ANF increased by more than 100% and returned to baseline at the end of hypercapnia. 5. Hypercapnia, but not hypoxia, induced an increase in left atrial and central venous pressures. 6. We conclude that hypercapnia increases plasma ANF concentration, and that this increase may be secondary to an increase of the left and right atrial pressures. These phenomena may explain the increase in diuresis and natriuresis which has been described during hypercapnia.

Animals↗
PubMed1985

Effect of the standardized Ginseng Extract G115 on the metabolism and electrical activity of the rabbit's brain.

The objective of this original investigation was to study the effect of the standardized Ginseng Extract G115 on the metabolic activity and ECoG of the rabbit's brain. The results showed significant increase of the glucose uptake with simultaneous significant reduction of the lactate, pyruvate and lactate/pyruvate ratio. These findings indicate shift of glucose utilization by the drug from anaerobic to the more economical pathway. G115 was also shown to produce a desynchronizing effect on the electrocorticogram (ECoG) which correlated well with the biochemical findings.

Animals↗
PubMed1976

Psychometric assessment of the therapeutic efficiency of antidepressant agents.

A clinical trial of four weeks duration was conducted involving a total of thirty depressed patients, of both sexes, aged between twenty and thirty-four years. The total number of patients was divided into three groups of ten patients each. One group received amitriptyline, the second group was administered noxiptyline and the third group was given dibenzepine. All drugs were administered orally. Patients were submitted to psychometric testing before and after drug administration. The tests used included the 'Hamilton Rating Scale for depression', the 'Hildreth Feeling Scale' and the 'D Scale' and the 'Trail Making Test' for the evaluation of psychomotor retardation. It was concluded that the Hamilton Rating Scale was the most relatively sensitive test utilized in assessing the depressive state and its improvement. Amitriptyline was found to be mostly anxiolytic; noxiptyline controlled both depression and anxiety to approximately the same extent; and dibenzepine was found to be a mood-elevating drug with an energizing action.

Adult↗