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Biomedical subjects

S A Omar

Publications and source records attributed to S A Omar.

At least 37 records · Page 2Linked to original sources
PubMed1986

Renal biopsy in Saudi children with nephrotic syndrome not responsive to corticosteroid: a preliminary report.

Percutaneous renal biopsy was done in 25 Saudi children whose nephrotic syndrome did not respond to prednisolone. The histologic diagnosis was mesangial proliferative glomerulonephritis in 11 cases; an additional two biopsies had features of both mesangial proliferative glomerulonephritis and focal segmental glomerulosclerosis. Immunofluorescence was abnormal in 16 out of 21 patients, with IgM as the most frequently detected immunogen.

Adolescent↗
PubMedDate not supplied

Co-trimoxazole compared with sulfadoxine-pyrimethamine in the treatment of uncomplicated malaria in Kenyan children.

Sulfadoxine-pyrimethamine (SP) and co-trimoxazole were both effective in reducing fever, clearing parasitaemia and improving anaemia in children aged < 5 years with uncomplicated malaria in 2 Kenyan endemic sites, Oyugis in the west and Tiwi on the coast. We compared the efficacy of these 2 regimens (in May-July 1998) by evaluating clinical and parasitological responses over 14 days. The combined incidence of parasitological failure for the combined sites for co-trimoxazole was 14/123 (11%) and for SP 23/145 (16%) (RR 0.72, 95% confidence interval [CI] 0.31-1.46, P = 0.289). The 14-day clinical failure rate for the combined sites for co-trimoxazole was 4/123 (3.3%), and for SP 8/145 (5.5%), (RR 1.69, 95% CI 0.91-3.15, P = 0.129). The results indicate that the risk of treatment failure for the 2 regimens was similar. The antimalarial use of co-trimoxazole in uncomplicated malaria needs further investigation, since the 10-12-h elimination half-life of both components should reduce selective pressure for resistance. In addition, use of a 2-day high-dose course, tested previously, requires further study to demonstrate its efficacy.

Acute Disease↗
PubMedDate not supplied

Can pretreatment screening for dhps and dhfr point mutations in Plasmodium falciparum infections be used to predict sulfadoxine-pyrimethamine treatment failure?

This study examines the relationship between malaria treatment failure after sulfadoxine-pyrimethamine (S-P) chemotherapy and presence of mutations in the Plasmodium falciparum dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr) genes (associated with resistance in vitro to S and P) before treatment. In Kenya, 38 malaria patients in a holoendemic area, and 21 in an epidemic area, participated in the trial in 1997-98. In the 2 areas, drug failure occurred in 76% and 75% of cases where any mutation in dhfr was seen (positive predictive values 76% and 75%: P = 0.003 and 0.008) and an identical association was seen with dhfr Asn-108. In the holoendemic area all occurrences of > or = 2 mutations in dhfr predicted drug failure. Only 3 instances were seen in the epidemic focus, but treatment failed in all. Only in the epidemic focus, 7 (88%) of 8 occurrences of > or = 1 mutations in dhps, and all occurrences of the Gly-437 allele of dhps, predicted failure. Association between mutations in dhps and mutations in dhfr was noted in the combined sites, irrespective of outcome. Although this makes the relationship of combined dhfr and dhps mutations to failure more difficult to interpret, it nevertheless supports S-P selection acting on both genes. In the holoendemic site, treatment success increased with age. In this location, acquired immunity may mask the impact of mutations in dhps, since sulfadoxine is a less effective treatment than pyrimethamine.

Adolescent↗
PubMedDate not supplied

Inhibition of growth and mycotoxin production of Alternaria alternata inhabiting decayed fruits by pesticides.

The effect of the two pesticides, cuprosan and sumi oil, on growth and mycotoxin production by two strains of Alternaria alternata isolated from decayed fruits was studied. Mycelial biomass of the two strains was significantly inhibited with most applied doses, however, cuprosan was most effective. Sumi oil exhibited significant inhibitory effect on the Alternaria strain isolated from decayed lemons, whereas, it suppressed mycelial biomass of that isolated from decayed tomatoes at only higher doses (250 ppm). Mycelial respiration of the two tested strains was mainly inhibited by most used does. However, CO2 evolution was occasionally promoted. Synthesis of alternariol (AOH) and its monomethyl ether (AME) by the examined strains was mainly inhibited by pesticide application in a manner similar to that of mycelial growth.

Alternaria↗
PubMedDate not supplied

A new approach to encapsulating nonsteroidal anti-inflammatory drugs. I. Bioavailability and gastric ulcerogenic activity.

Different classes of nonsteroidal anti-inflammatory drugs, NSAIDs, were separately coated with cationic (E) and anionic (L) Eudragit using the fluidized bed technique. The bioavailability and ulcerogenic activity of coated and uncoated drugs were assessed in rats. The cationic coat decreased the ulcerogenic activity in all classes of NSAIDs and increased the bioavailability only in acidic and enolic ones. The anionic coat, however, increased the bioavailability in basic NSAIDs.

Animals↗
PubMedDate not supplied

A new approach to encapsulating nonsteroidal anti-inflammatory drugs. III. Coating acidic as well as basic nonsteroidal anti-inflammatory drugs with cellulose derivatives having different functional groups.

Acidic and basic nonsteroidal anti-inflammatory drugs were encapsulated with cellulose derivatives having different functional groups, acidic (carboxymethyl cellulose), basic (chitosan), and neutral (hydroxypropylmethyl cellulose). The properties of the microcapsules were studied and the interaction of the drugs with chitosan was assessed.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMedDate not supplied

A new approach to encapsulating nonsteroidal anti-inflammatory drugs. IV. Effect of cellulose derivatives with different functional groups on the bioavailability and gastric ulcerogenic activity of acidic as well as basic nonsteroidal anti-inflammatory drugs.

The bioavailability and gastric ulcerogenic activity of oxyphenbutazone and glafenine (acidic and basic nonsteroidal anti-inflammatory drugs), coated with different cellulose derivatives were assessed in albino rats. The cellulose derivatives chosen have different functional groups, acidic (carboxymethyl cellulose), basic (chitosan) and neutral (hydroxypropylmethyl cellulose). The bioavailability was dependent on the drug and polymers. Generally, all the cellulose derivatives chosen decreased the gastric ulcerogenic activity of the drugs studied.

Animals↗
PubMedDate not supplied

Reduced beta adrenergic responsiveness in isolated rabbit atria during hypothermia.

Beta adrenergic agonist isoprenaline (8x10(-6)M) produced a 500% increase in inotropic and 90% increase in the chronotropic responses of isolated rabbit atria at 37 degrees C. On cooling the atria to 23 degrees C, these responses were significantly reduced to 87% and 30% respectively. Similar results were obtained with adrenaline, but isoprenaline was more potent. The positive chronotropic and inotropic responses to isoprenaline were effectively blocked by propranolol and practolol at 37 degrees C whereas at 23 degrees C these beta blockers were unable to block even minor positive responses obtained by isoprenaline at this temperature. On the contrary at 23 degrees C, phenylephrine (alpha adrenergic agonist) produced marked positive chronotropic and inotropic effects indicating enhancement of alpha adrenoceptor activity at lower temperatures. This also suggests that reduced beta receptor activity at lower temperature is not due to a generalised depression of adrenoceptors as a result of hypothermia. Rewarming of atria to 37 degrees C restored the beta adrenoceptor responsiveness to previous level. It appears that ambient temperature is important im maintaining normal beta adrenergic activity of the atria.

Animals↗
PubMedDate not supplied

Calcium pyrophosphate crystal formation in aqueous solutions.

Pseudogout is characterized by the deposition of calcium pyrophosphate dihydrate, triclinic [CPPD(T)] and calcium pyrophosphate dihydrate, monoclinic [CPPD(M)] crystals in articular connective tissues. We studied aqueous solutions over a range of calcium chloride/sodium pyrophosphate concentrations to determine the ionic conditions under which these particular salts form. At 37 degrees C, CPPD(T) forms when [PPi]t greater than or equal to 10(-4), while formation of CPPD(M) occurs at 10(-3) M < [PPi]t less than or equal to 10(-2) M. When [Na+]t > 120 mM, calcium disodium pyrophosphates precipitate. With 1 mM Mg++, CPPD(M) forms at [PPi]t > 10(-3) M, mixed with a calcium magnesium pyrophosphate at [PPi]t greater than or equal to 10(-2) M. We conclude that CPPD(T) and CPPD(M) crystals form in a restricted ratio and range of [Ca++]t and [PPi]t and that other ions, particularly Mg++ and Na+, affect the nature of the crystal products formed.

Calcium Pyrophosphate↗
PubMedDate not supplied

Calcium pyrophosphate crystal formation in model hydrogels. II. Hyaline articular cartilage as a gel.

We studied calcium pyrophosphate crystal formation in an in vitro cartilage system. Two parallel troughs were excavated in tibial plateau articular cartilage obtained postmortem. One well was filled with solid sodium pyrophosphate, the other with calcium chloride. After incubation for 24 h at either 10 degrees C or 37 degrees C the precipitate band between the troughs was analyzed for the size and nature of crystals present. In subsequent experiments, the cartilage was pretreated by laceration, contusion, trypsin or hyaluronidase denaturation. We found that cartilage denaturation resulted in formation of larger crystals but that the crystal product in all experiments was identical, alpha CaNa2P2O7.4H2O a nonphysiologic crystal.

Calcium Pyrophosphate↗
PubMedDate not supplied

Experimental cholesterol crystal arthropathy.

To understand the role of cholesterol crystals in the pathogenesis of synovial effusions, we studied the articular tissue reaction to an intraarticular injection of cholesterol crystals in rabbits' knees. With the right knee as control, the left knees of 14 adult male, white, New Zealand rabbits were injected with 11 mg of cholesterol crystals suspended in 0.5 ml of saline. At 4, 8, 24, 48 h and at 7, 14, 28 and 56 d postinjection, the animals were autopsied and these tissues, including synovial fluid (SF), examined by light and transmission electron microscopy. Crystal injection produced an acute synovitis which peaked at 24 h coincident with phagocytosis of crystals in SF. Cholesterol crystals persisted within the synovium throughout the experiment resulting in cholesterol granulomata, synovial lining cell hyperplasia and synovial fibrosis. Relative to urate and pyrophosphate crystals, cholesterol crystals appear to have weak phlogistic potential. Because of their insolubility and resistance to cellular degradation, crystals persist within the synovium for prolonged periods. This results in a chronic proliferative synovitis and fibrosis.

Animals↗
PubMedDate not supplied

Effects of magnesium on isolated rabbit atria.

The cardiac effects of magnesium were studied on 40 spontaneously beating rabbit atria at 37 degrees C. Magnesium administered in doses of 30, 60, 120 and 240 mmol elicited dose dependent negative inotropic and chronotropic responses. Larger doses above 240 mmol caused complete atrial arrest. Further it was observed that propranolol with magnesium became more effective in blocking the positive chronotropic and inotropic responses to isoprenaline. The finding is interesting and suggestive that magnesium could be employed either alone or in combination with propranolol in treatment of arrhythmias which are non-responsive to propranolol.

Animals↗