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Biomedical subjects

M A Mohamed

Publications and source records attributed to M A Mohamed.

At least 19 recordsLinked to original sources
PubMed1998

Experimental induction of renal lesions in chickens.

The present work was conducted to investigate the possibility of inducing renal lesions in chickens subcutaneously or orally inoculated with E. coli [E. coli O1K67(B12)], Staphylococcus aureus and Actinomyces pyogenes. The strains were previously isolated from the kidneys of broilers showing different pathological lesions. The gross lesions observed in the kidneys included enlargement, congestion, haemorrhagic spots in addition to dilatation and distension of the ureters. The microscopic lesions were mainly interstitial nephritis. The lesions were acute and changed gradually to subacute or chronic nephritis. The glomerular lesions were not common. The wall of the primary branches of the ureter and the ureters was heavily infiltrated with inflammatory cells, also granular and albuminous casts were seen in the renal tubules. The lesions were not related to the inoculated pathogen, although they were more severe in chickens inoculated with E. coli and Staph. aureus more than in Actinomyces pyogenes. Reisolation of the inoculated pathogens was more successful from the birds inoculated subcutaneously than from those infected orally.

Actinomycosis↗
PubMed1997

Disposition of intravenous theophylline in asthmatic children: Bayesian approach vs direct pharmacokinetic calculations.

Fifteen children (mean age +/- SD: 6.4 +/- 3.4, range: 2-12 years) with an acute asthma attack were treated by an intravenous dosage regimen of theophylline (30 min loading infusion of 6 mg/kg body weight followed by a constant infusion of 1 mg/kg, twice for 6 hr each). Three blood samples were drawn (each 15 min after the bolus infusion and after the two infusion periods of 6 hr). Plasma clearance (CL), apparent volume of distribution (Vd) and elimination half-life (t1/2) were estimated by the Bayesian approach using either only the first peak level (Bay 1) or all three monitored concentrations (Bay 3). These values were compared to the parameters calculated by a standard pharmacokinetic procedure (SC). Therapeutic steady state plasma levels around 12 micrograms/ml were rapidly achieved, and the pharmacokinetic parameters (CL = 1.1-1.5 ml/min/kg, Vd = 0.44-0.50 l/kg, t1/2 = 3.5-5.4 hr) differed slightly between the 3 methods applied. There was a significant linear correlation between the Bayesian-derived and SC-derived pharmacokinetic parameters. However the method Bay 1 seems to overestimate the elimination rate of theophylline more than Bay 3 does. In conclusion, Bayesian-based therapeutic plasma level monitoring (Bay 3 are better than Bay 1) can be utilized for individualized pharmacokinetic calculations and proper dosage predictions of theophylline in pediatric patients.

Asthma↗
PubMed1991

Effect of some arsenic antagonists on the toxicity, distribution and excretion of arsenite and arsenate in rats.

1. Arsenite and arsenate poisoned rats were treated with either BAL (2,3-dimercapto-1-propanol), penicillamine (PA) (beta-beta dimethyl cystein) or selenium (Se) (as sodium selenite). 2. The minimal dose of each antagonist that treated arsenic-induced lethality (causing 100% survival) was the same for both arsenite and arsenate. 3. Arsenic mobilization from the tissues (blood, kidney, liver, lungs, spleen, muscles, brain, heart) and its excretion in urine and feces were higher in arsenite-intoxicated animals than in arsenate-intoxicated ones. 4. The effect of each antagonist, when injected alone, on the urinary and fecal excretion of endogenous metals (Cu, Zn, Fe, Ca and Mg) was also examined. 5. The results indicated marked differences in the relative ability of BAL, PA and Se to increase the excretion of the metals.

Animals↗
PubMed1991

Purification and characterization of purine nucleoside phosphorylase from developing embryos of Hyalomma dromedarii.

Purine nucleoside phosphorylase from Hyalomma dromedarii, the camel tick, was purified to apparent homogeneity. A molecular weight of 56,000 - 58,000 was estimated for both the native and denatured enzyme, suggesting that the enzyme is monomeric. Unlike purine nucleoside phosphorylase preparations from other tissues, the H. dromedarii enzyme was unstable in the presence of beta-mercaptoethanol. The enzyme had a sharp pH optimum at pH 6.5. It catalyzed the phosphorolysis and arsenolysis of ribo- and deoxyribo-nucleosides of hypoxanthine and guanine, but not of adenine or pyrimidine nucleosides. The Km values of the enzyme at the optimal pH for inosine, deoxyinosine, guanosine, and deoxyguanosine were 0.31, 0.67, 0.55, and 0.33 mM, respectively. Inactivation and kinetic studies suggested that histidine and cysteine residues were essential for activity. The pKa values determined for catalytic ionizable groups were 6-7 and 8-9. The enzyme was completely inactivated by thiol reagents and reactivated by excess beta-mercaptoethanol. The enzyme was also susceptible to pH-dependent photooxidation in the presence of methylene blue, implicating histidine. Initial velocity studies showed an intersecting pattern of double-reciprocal plots of the data, consistent with a sequential mechanism.

Amino Acids↗
PubMed1989

Polyacrylamide gel miniaturization improves protein visualization and autoradiographic detection.

Polyacrylamide gels shrink to one-quarter of their original area when soaked in a 50% (w/v) solution of polyethylene glycol. Gel miniaturization improves the contrast of protein bands, with four valuable consequences. (i) A 5- to 10-fold increase in sensitivity for Coomassie blue is observed. (ii) Gels are more durable; i.e., they resist tearing when wet and they do not crack during drying under vacuum. (iii) Shrunken gels give sharper photographic images and provide better interlane protein band comparisons. (iv) Condensed protein bands lead to an increased sensitivity for detecting low-abundance, radioactively-labeled proteins by fluorography.

Affinity Labels↗
PubMed1985

The effect of aflatoxin B1 on the utilization of serum calcium.

The mathematical analysis for plasma disappearance curve of aflatoxicosed animals, subsequently injected with 45Ca was determined. The analysis showed that the three main compartments of the calcium pool (plasma, bone and the labile calcium pool on the surface of bone and soft tissues) had been affected. Specifically, the fractional rate constant for migration of 45Ca from plasma pool to the labile pool had been diminished to its third value. This led to a corresponding reduction in the calcium content of the bone ash. The probable mechanism by which aflatoxin B1 affects calcium dynamics may be interpreted by the inhibitory effect of aflatoxin in the hydroxylation mechanism of vitamin D3 into an active intermediate. During aflatoxicosis (induction of 15 days) the animals entered a state of calcium deficiency, secondary to intestinal absorption inhibition. This was followed by bone resorption and disturbance of the fractional removal rate constant among different calcium compartments.

Aflatoxin B1↗
PubMed1984

Effect of oral contraception on serum bile acid.

Eighteen normal women, 20 with active urinary schistosomiasis, and 25 with past histories of viral hepatitis were given a contraceptive pill containing 0.05 mg ethinyl estradiol and 0.5 mg levonorgestrel for six consecutive cycles. Serum bile acid levels were measured by enzyme immunoassay method before and after 3 and 6 months of use. Simultaneously, conventional liver function tests (serum bilirubin, transaminases, alkaline phosphatase and albumin) were done. Serum bile acid concentration was not significantly changed by the contraceptive use in any group. The concentration of cholylglycine (the main bile acid measured) did not correlate with the values of any of the other tests. Pretreatment values of serum cholylglycine were significantly lower in the past-hepatitis group. The difference was maintained during treatment.

Alanine Transaminase↗
PubMed1972

Siderosis bulbi.

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Adult↗