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Biomedical subjects

S Mahmoud

Publications and source records attributed to S Mahmoud.

34 records · Page 2Linked to original sources
PubMed1986

The combination of 17 alpha-hydroxyprogesterone and 11-epicortisol prevents the delayed feedback effect of natural and synthetic glucocorticoids.

Subcutaneous injection of 400 micrograms/100 g body weight of corticosterone (B) 2 h previously in male rats prevented the stress response, as assessed by the ability of adrenal glands removed from these animals to produce endogenous B. Two injections of a combination of 17 alpha-hydroxyprogesterone and 11-epicortisol, the first given 30 min before and the second with the B, were able to block this inhibitory effect on the stress response. Neither of the steroids alone was effective in this regard. The combination was also effective against the early delayed feedback effects of 400 micrograms/100 g body weight cortisol, prednisolone or beclomethasone dipropionate in the same system. The minimum effective dose for reversal of feedback by B or beclomethasone dipropionate (2 mg/100 g body weight of each antagonist) was lower than that required for the same effect against prednisolone or cortisol (5 mg/100 g body weight). Previous injection of B also abolished the ability of anterior pituitary gland fragments to respond to corticotropin-releasing factors (CRFs) added in vitro, an effect which was not abolished by the injection of the combination of putative antagonistic steroids. From experiments designed to measure the ability of 17 alpha-hydroxyprogesterone and 11-epicortisol to compete with 3H-corticosterone in binding to macromolecular components in hypothalamic, hippocampal and pituitary cytosolic preparations, it was deduced that the competition seen in the hypothalamic and hippocampal, rather than the pituitary, preparations was in better accord with the effect seen on the stress response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Diurnal variations in responsiveness of the hypothalamo-pituitary-adrenocortical axis of the rat.

Hypothalami, anterior pituitary gland segments and adrenal glands were removed from female Wistar-derived rats decapitated at various times of the day. Blood and tissue hormone concentrations were measured and the tissues challenged with appropriate stimuli in vitro. Both bioactive and immunoreactive corticotrophin-releasing factor (CRF) content of the hypothalami were significantly higher in the evening than in the morning, as was the basal release of bioactive CRF in vitro. The response of the hypothalami to serotonin or acetylcholine added in vitro did not change with time of day. Basal bioactive and immunoreactive adrenocorticotrophin (ACTH) release from the anterior pituitary gland was significantly increased in the evening, as was the response to synthetic ovine CRF in vitro. Plasma ACTH concentrations in intact rats given crude CRF (hypothalamic extract) in vivo were higher in the evening at all times after injection tested, but this difference was markedly reduced in animals with mediobasal hypothalamic lesions. Corticosterone released basally from adrenal glands in vitro was significantly increased in the evening and the response to added ACTH 1-24 was slightly enhanced. For adrenal glands removed from lesioned rats, the pattern was reversed, corticosterone release in vitro being lower in the evening for all doses of ACTH added. Similarly in vivo, in intact rats given ACTH 1-24, plasma corticosterone concentrations and corticosterone release in vitro from adrenal glands removed after the injection were higher in the evening. After the placement of basal hypothalamic lesions, the situation was reversed, the response to ACTH administration in vivo being greater in the morning.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1984

Application of orthogonal functions to spectrophotometric analysis of the preservatives benzylalcohol, phenol and parabens in aqueous cyanocobalamin solutions.

The orthogonal polynomials P3 and P2, 12 and 8 points, at 2 nm intervals over certain wavelength ranges were used for the spectrophotometric analysis of benzylalcohol, phenol or parabens in aqueous cyanocobalamin solutions. The 12 point-methods proved to be more sensitive and direct and to have sufficient accuracy and precision.

Benzyl Alcohol↗
PubMed1983

The characteristics of post tur blood loss: a preliminary study.

Peroperative and postoperative blood loss was studied in 20 patients. Both peroperative and postoperative blood loss was found to correlate together (p less than 0.05) and with the weight of resected tissue (p less than 0.05). The characteristics of the postoperative blood loss demonstrated a strong negative correlation with time, and calculation of the t50 showed that a 50% reduction in postoperative blood loss occurred within 16 h.

Aged↗
PubMed1976

[Beef kidney carbonic anhydrases in affinity chromatography and radial immunodiffusion].

The absence of low activity carbonic anhydrase in the parenchyma of bovine kidney is demonstrated by high specific methods such as affinity chromatography on "CH-Sepharose 4 B"-sulfanilamide and radial immunodiffusion; thus, the high activity carbonic anhydrases C I and C II seem to be the only forms in this tissue. Their identity with the carbonic anhydrases of the erythrocyte suggests that their biosynthesis must be regulated by the same structural gene working alone on these two tissues.

Animals↗
PubMedDate not supplied

Substance P analogues function as bombesin receptor antagonists and inhibit small cell lung cancer clonal growth.

Human small cell lung cancer (SCLC) produces and secretes BN/GRP (bombesin/gastrin releasing peptide). Because BN stimulates the growth of SCLC cells and these cells have receptors for BN-like peptides, it is important to define agents which disrupt this self-promoting autocrine growth cycle. Here, substance P analogues were evaluated as BN receptor antagonists using SCLC cell lines. (D-Arg1, D-Pro2, D-Trp7.9, Leu11) substance P [(APTTL)SP] was one of the more potent analogues tested in inhibiting BN-like peptide receptor binding with an IC50 value of 1 microM. Micromolar concentrations of (APTTL)SP antagonized BN receptor mediated elevation of cytosolic Ca2+ levels and decreased the colony formation in soft agarose. These data suggest that SP analogues function as SCLC BN receptor antagonists and may be useful in disrupting the autocrine growth function of BN-like peptides.

Bombesin↗
PubMedDate not supplied

Red cell membrane lipids in thalassaemia.

Red cell and plasma lipids and their fractions were estimated in 20 cases of thalassaemia and 20 normal controls. In thalassaemia there was reduction in red cell lipids and their fractions, plasma lipids and their fractions, and derangement of liver functions. On the other hand, the intestinal fat absorption, morphology of intestinal mucosa and histochemical studies of fat absorption were normal. Hypolipidaemia may be possibly caused by deranged liver functions and is probably responsible for the diminution in erythrocyte lipids. A genetic factor producing reduction in red cell lipids may be also present.

Cell Membrane↗
PubMedDate not supplied

Study of red cell membrane lipids in glucose-6-phosphate dehydrogenase deficiency anemia.

Red cell membrane lipids and plasma lipids were studied in 20 patients with G.6.P.D. deficiency, during acute hemolysis and 45-60 days later-20 normal controls were similarly investigated. All lipids in G-6-P-D deficient cells were found to be diminished during the attack of hemolysis and to return back with the exception of lecithin to normal after recovery. Plasma cholesterol and phospholipids were markedly diminished during acute hemolysis, but slightly reduced on recovery.

Acute Disease↗