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S Abdalla

Publications and source records attributed to S Abdalla.

At least 37 records · Page 2Linked to original sources
PubMed1992

A one-minute oxidase test to detect Vibrio strains isolated from cultures on thiosulphate-citrate-bile salts-sucrose (TCBS) medium.

Vibrio cholerae is oxidase positive, a primary characteristic used to differentiate it from Enterobacteriaceae. But false negative oxidase test results have been obtained with colonies from thiosulphate-citrate-bile salts-sucrose (TCBS) agar medium. A rapid oxidase test procedure is described here. This takes 1 min, avoids false negative results and the necessity to grow the bacteria in a general-purpose medium. The bacteria may be recovered after the test and used for further investigations.

Culture Media↗
PubMed1992

Effects of dichloroglyoxime on isolated guinea-pig smooth muscle and atrium.

The effects of dichloroglyoxime (DCG) on isolated rings of aorta, main pulmonary artery, trachea and spontaneously-beating atrium of guines-pig were studied. DCG caused concentration- dependent relaxation of the epinephrine-contracted aortic and pulmonary artery rings and of the tone of tracheal rings. Propranolol caused a slight shift to the right in the concentration-effect curves of DCG on these preparations. Quinacrine, an inhibitor of the release of arachidonic acid and its metabolites, caused a significant shift to the right in the concentration-effect curves of DCG on the three preparations. Low concentrations of DCG increased the beating rate of the atrium, an effect which was blocked by propranolol but not by quinacrine whereas large concentrations decreased the beating rate, an effect which was not significantly affected by propranolol or by quinacrine. DCG also caused a concentration-dependent decrease in the contractility of the atrium and this effect was only slightly affected by propranolol or quinacrine. These observations suggest that the relaxant effect of dichloroglyoxime on the smooth muscle may not be mediated by the stimulation of beta adrenoceptors specifically although a nonspecific interaction with these receptors or with the contractile machinery of the cell cannot be excluded. Data with quinacrine suggest that the effects may be mediated by the release of an inhibitory metabolite of arachidonic acid. The results further suggest that in the atrium the effects of DCG may not be specific and they may be partially mediated by the release of catecholamines from the nerve endings.

Animals↗
PubMed1991

Mast cells in the rat gastric mucosa are not primarily responsible for PGD2 generation.

The present study investigates the contribution of gastric mast cells on PGD2 generation in rat gastric mucosa. Cold-restraint induced stress or i.v. carbachol injection methods were used for gastric mast cell degranulation. In 19 stressed, 15 carbachol-infused and 14 control rats, gastric mast cell counts and gastric mucosa PGD2 assay were performed. Gastric mucosal content of PGF2 alpha was also determined in carbachol infused and control rats. The mean number of gastric mast cells was significantly lower in stressed and carbachol infused than in control rats. Despite these differences in gastric mast cell counts, neither PGD2 or PGF2 alpha contents in the gastric mucosa were significantly different in mast cells degranulated rats than in control animals. These results suggest another source of PGD2 in the rat gastric mucosa other than mast cells.

Animals↗
PubMed1991

Observations on the pharmacology of thalicminine, an oxyaporphine alkaloid from Thalictrum isopyroides.

1. The effects of the oxyaporphine alkaloid thalicminine on guinea-pig isolated ileum, trachea, aorta and pulmonary artery and on blood pressure and heart rate of anesthetized guinea-pigs were studied. 2. Thalicminine (1-300 microM) caused the relaxation of the longitudinal ileal segments. The relaxation induced by 300 microM was followed by vigorous contractions. 3. Thalicminine caused only mild relaxation of the trachea. 4. Thalicminine (0.3-300 microM) caused concentration-dependent relaxation of epinephrine-precontracted aorta and main pulmonary artery. 5. Propranolol (1 microM) failed to reduce the relaxation or to affect the EC50 value of thalicminine on the ileum or the pulmonary artery. 6. Quinacrine (10 microM), on the other hand, potentiated thalicminine-induced relaxation and reduced the EC50 on the aorta and the pulmonary artery suggesting the interference of thalicminine with arachidonic acid metabolism. 7. In anesthetized animals, intravenous injections of 0.37-1.1 mg kg of thalicminine caused transient reduction of systolic and diastolic blood pressure and heart rate. Both parameters returned to their normal values in about 10 min.

Animals↗
PubMed1989

Preliminary observations on the pharmacology of petaline chloride, a quaternary alkaloid from Leontice leontopetalum.

1. Low concentrations of petaline chloride (1-300 micrograms/ml) caused relaxation of the epinephrine-contracted aorta, contraction of the ileum, and no effect on the trachea. 2. Larger concentrations (up to 3 mg/ml) caused nonsustained large contractions of the aorta and the trachea and increased the amplitude of the phasic contractions of the ileum. 3. The above effects were not inhibited in the presence of atropine. 4. Petaline chloride increased, in a concentration-dependent manner, the contractions of the spontaneously-beating atrium and the isolated perfused heart. 5. The effects of petaline chloride on the atrium and on the perfused heart were not affected by propranolol but were significantly reduced in the presence of quinacrine, suggesting the participation of arachidonic acid metabolism to this effect. 6. In anesthetized rats, petaline chloride (0.3-3 mg/100 g body weight; i.p.) increased both the systolic and diastolic blood pressure and increased the heart rate.

Alkaloids↗
PubMed1989

Effects of 3,3'-di-O-methylquercetin on guinea-pig isolated smooth muscle.

The effects of the flavone 3,3'-di-O-methylquercetin (DOMQ) have been examined and compared with those of quercetin, on guinea-pig isolated ileum, trachea, and main pulmonary artery (MPA). Except for transient contractions induced by low concentrations (10(-8)-3 x 10(-6) M), DOMQ and quercetin (up to 3 x 10(-4) M) caused reduction of the tone and the phasic contractions of the ileum. A23187 reversed the inhibitory effects of quercetin but not those of DOMQ. DOMQ and quercetin caused concentration-dependent relaxation of the trachea and the adrenaline-contracted MPA. DOMQ shifted to the right the concentration-effect curves induced by acetylcholine on the ileum and the trachea, and by adrenaline on MPA and those induced by CaCl2 on ileum, trachea and MPA. DOMQ also inhibited the contractions induced, in Ca2+-free EGTA-containing buffer, by histamine on ileum and by adrenaline on MPA. These observations suggest that DOMQ inhibits Ca2+ influx, Ca2+ release from intracellular stores and, more likely, Ca2+ binding to intracellular receptor proteins.

Acetylcholine↗
PubMed1989

Rapid detection of gastric Campylobacter pylori colonization by a simple biochemical test.

A simple and rapid urease test to detect Campylobacter pylori infection was evaluated with bacterial culture as the "gold standard." The test was compared with the Gram stain and the conventional Christensen urease test. The culture method detected C. pylori in 29 of 49 gastric biopsy specimens. The rapid urease test showed 27 positive samples within 1 h at 55 degrees C (specificity, 100%; sensitivity, 93%) and 18 at room temperature (specificity, 100%; sensitivity, 62%). The Gram stain exhibited a sensitivity of 86% and a specificity of 91%. The conventional Christensen urease test detected C. pylori in only 4, 10, and 18 samples after 24, 48, and 72 h, respectively (sensitivities, 12, 36, and 60%, respectively; specificities, 95, 95, and 83%, respectively). We conclude that the rapid urease test is simple and highly specific for the detection of C. pylori and that it can be performed with small amounts of sample.

Adult↗
PubMed1988

Effects of hispidulin, a flavone isolated from Inula viscosa, on isolated guinea-pig smooth muscle.

1. In small concentrations (10(-7)-3 X 10(-6) M), hispidulin caused concentration-dependent contraction of isolated guinea-pig ileum and only mild relaxation of guinea-pig tracheal rings. 2. Larger concentrations (up to 3 X 10(-4) M) caused concentration-dependent relaxation of the ileum and the trachea. All the effects on the ileum and the trachea are reversible upon removal of the compound. 3. In concentrations from 10(-7) to 3 X 10(-4) M, hispidulin had no effect on the tone of the epinephrine-contracted rings of the guinea-pig main pulmonary artery. 4. Hispidulin caused a shift to the right of the acetylcholine concentration-effect curves on ileum and trachea and significantly inhibited the maximum contractions induced by acetylcholine. 5. In Ca2+-free, depolarizing solution, hispidulin caused both a shift to the right, and an inhibition of the maximum contractions, of the CaCl2 concentration-effect curves on ileum, trachea and pulmonary artery. 6. In Ca2+-free, EGTA-containing solution, hispidulin caused concentration-dependent inhibition of the contractions induced in the pulmonary artery by epinephrine and in the ileum by histamine. 7. These observations suggest that hispidulin may interfere with Ca2+ binding to the Ca2+-receptor protein(s) in the smooth muscle cell and/or with the agonist-induced Ca2+-release from intracellular stores. Less likely, hispidulin may interfere with Ca2+ influx through smooth muscle cell membrane.

Animals↗
PubMed1983

The anaemia of Plasmodium falciparum malaria.

Anemia is an important complication of P. falciparum malaria infection. This paper describes recent studies that have attempted to define some of the pathophysiological mechanisms involved in different forms of infection and at different stages of the illness. After an acute infection there is a steady fall in the haemoglobin level with an inappropriate reticulocyte response. Current evidence indicates that this form of anaemia may result from a combination of acute sequestration of iron in the reticuloendothelial system associated with a shortened red cell survival. Recent studies indicate that there may be a dyserythropietic component as well. The mechanism for the shortened red cell survival is uncertain; although it may be due in part to sequestration of parasitized cells, the haemoglobin level continues to fall for several weeks after the acute episode and other factors must be involved. The role of immune haemolysis appears to be relatively small. It is becoming apparent that severe dyserythropoiesis with minimal haemolysis plays a major role in the anaemias of Plasmodium falciparum infection, particularly in immune individuals. This phenomenon has been studied by both light and electron microscopy and by assessing the in vitro kinetics of erythroid precursor proliferation. The results indicate a major defect in erythroid maturation with a significant degree of erythrophagocytosis. Although these studies have provided a clearer picture of the pathophysiology of anaemia at different phases of P. falciparum infection, there is still little indication of how the basic changes in red cell production and survival are mediated.

Acute Disease↗
PubMed1982

Studies on segmental differences in sensitivity to adrenergic agonists in pulmonary arteries isolated from the guinea-pig.

This study was designed to examine the existence and possible mechanisms of segmental differences in sensitivity to adrenergic substances in the pulmonary vasculature of the guinea pig. The main pulmonary artery was found to be less sensitive to epinephrine, norepinephrine and phenylephrine than its left and right main branches. Because there were no differences in sensitivities between the left and right branches, most comparisons were made between the main and left branches. The difference in sensitivity was larger for adrenergic agonists which are known to be taken up by adrenergic neurons (epinephrine, norepinephrine, phenylephrine) than for an agonist which is not taken up by these neurons (methoxamine). The left artery from reserpine-treated animals was only slightly more sensitive (1.5-fold) to barium chloride than the main pulmonary artery. Cocaine potentiated to a greater extent in the main than in the left pulmonary artery the amines which are taken up by adrenergic neurons. The left arterial branch was less responsive to transmural electrical stimulation than the main artery in the absence and presence of cocaine. [3H]Norepinephrine uptake was larger in main arterial segments than in the branches and histochemical fluorescence studies demonstrated a greater degree of adrenergic innervation in the proximal segments. The results indicate that a major explanation for the differences in sensitivity between the vascular segments is a smaller degree of adrenergic neuronal uptake of agonist in the arterial branches.

Animals↗
PubMed1982

The direct antiglobulin test in P. falciparum malaria.

The direct antiglobulin test (DAT) was performed on 134 Gambian children with P. falciparum malaria. 52 children had a positive DAT and in 25 this was due to the adherence of C3 to their red cells whilst 13 had sensitization with IgG as well as C3. Sensitization with C4 alone or associated with IgG and/or C3 was only rarely found. The haemoglobin levels and reticulocyte counts were not significantly different in patients with a positive DAT from those with a negative DAT. The children with positive IgG DAT, however, were of a significantly older age group and had significantly higher parasitaemias at presentation than children with complement components only or with a negative DAT. In vitro assay of phagocytosis by peripheral blood monocytes (PBM) showed that PBM from malarious patients were less active in phagocytosis than normal male adult Caucasian PBM. Neither PBM from malarious patients nor normal adult Caucasians PBM showed phagocytosis of cells from DAT positive malarious children. The same in vitro assay was used to test for the presence of opsonizing anti-schizont antibodies in the sera of these children and in adult Gambians. This revealed the presence of a schizont specific opsonizing antibody in the sera of adult Gambians and in the sera of children with a positive DAT due to IgG but not in sera of patients with a negative IgG. These findings indicate that a positive IgG DAT in malaria does not necessarily lead to excess haemolysis of non-parasitized red cells. The presence of a schizont opsonizing antibody, leading to in vitro phagocytosis, in the sera of children with a positive DAT and in sera from adult Gambians indicates a relationship between the development of the positive DAT and acquisition of protective malarial immunity.

Adolescent↗
PubMed1982

Cell cycle distribution of erythroblasts in P. falciparum malaria.

The cell cycle distribution of the erythroblasts of 6 Gambian children with P. falciparum malaria was determined using the technique of combined Feulgen microspectrophotometry and 3H-thymidine autoradiography. The data showed evidence of a perturbation of erythroblast kinetics in all 6 children. The abnormalities were more marked in the children with chronic malaria than in those with acute malaria and predominantly affected the early polychromatic erythroblasts. The disturbances observed in chronic malaria included an increased proportion of cells in the G2 phase and an arrest during the progress of some cells through the S phase. The latter defect was not seen in the children with acute malaria.

Acute Disease↗