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Biomedical subjects

M A Shalaby

Publications and source records attributed to M A Shalaby.

15 recordsLinked to original sources
PubMed1992

Etiology of sarcoplasmic reticulum calcium release channel lesions in doxorubicin-induced cardiomyopathy.

Alterations in the native function of the ryanodine-sensitive Ca2+ release channel complex of sarcoplasmic reticulum (SR) isolated from rat cardiac ventricles during acute and chronic exposure to doxorubicin are examined. Compared to control SR, actively loaded SR from animals exposed to a single intravenous dose of doxorubicin exhibit faster rates of doxorubicin-induced Ca2+ release and the occupancy of [3H]ryanodine is significantly enhanced with subsequent exposure of SR membranes to doxorubicin in vitro. One week after acute exposure to doxorubicin in vitro, the EC50 for activation of the binding of [3H]ryanodine by Ca2+ is not significantly different from control SR. However, the persistence of doxorubicin-sensitized SR channels appears to be latent since repeated exposure to doxorubicin in vitro significantly enhances receptor occupancy in SR obtained from the treated rats compared to control SR. Ryanodine receptors from rats chronically exposed to doxorubicin consistently exhibit a higher sensitivity to activation Ca2+ which persists at least 4 weeks following the last injection of drug. Chronic exposure produces a concomitant reduction in the capacity of [3H]ryanodine binding sites. The marked decrease in receptor density observed with SR from doxorubicin-treated rats coincides with significant reduction in body weight, suggesting a possible influence of nutrition. However, sodium dodecyl sulfate polyacrylamide electrophoresis indicates no significant loss of the high molecular weight subunit of the ryanodine receptor, suggesting that loss of [3H]ryanodine-binding capacity may be the result of progressive and permanent channel desensitization. Consistent with desensitized receptors, membrane vesicles prepared from rats chronically exposed to doxorubicin take up significantly more Ca2+ and exhibit significantly reduced rates of doxorubicin or Ca2+/ryanodine induced Ca2+ release. The data demonstrates (i) doxorubicin inflicts cumulative SR channel lesions in vivo, (ii) a persistent sensitization of the SR channel to activation by Ca2+ and (iii) a significant and apparently irreversible reduction in the number of functional channel complexes.

Animals↗
PubMed1992

Application of Corynebacterium cutis lysate as an immune stimulant in cattle.

An ultrasonicated lysate of Corynebacterium cutis (Ultracorn, Virbac, France) was administered to 10-day-old calves, 5-month-old calves, and pregnant dams kept under Egyptian environmental conditions. Ninety-five calves and 50 dams were used in the study. All animals were treated with 2 ml/100 kg body weight of killed C cutis. Its effects on body weight gain and on calf mortality and morbidity were recorded. The results obtained showed that treated calves had greater weight gains, reduced susceptibility to common viral pathogens, and lower mortality. When given simultaneously with rinderpest vaccine, an immunopotentiating or adjuvant effect was seen. Thus, treated calves had higher neutralizing antibody titers to rinderpest as compared with untreated calves. When administered to pregnant cows in the last month of pregnancy, the offspring of these animals had higher birth weight, better weight gain, and reduced morbidity.

Adjuvants, Immunologic↗
PubMed1990

Dynamic-interaction of vitamin K and levamisole on phenylbutazone activities.

The results showed that co-administration of either vitamin K or levamisole along with phenylbutazone abolished the latter's anti-inflammatory and antipyretic activities and reduced its analgesic effect. Prolonged administration of phenylbutazone alone to rats for 21 days increased significantly serum glutamate oxalacetate transaminase (SGOT) activity, urea and creatinine concentrations, while it decreased with significance uric acid concentration in the serum. Vitamin K, when administered together with phenylbutazone, reduced its effect on SGOT activity and creatinine concentration. Levamisole antagonised the uricosuric effect of phenylbutazone, when both were concomitantly given. Histopathological examination of the liver of rats, given phenylbutazone alone, showed mild degenerative changes, whereas in combination with levamisole these changes were exacerbated. Kidney showed oedema, degeneration, congestion, and haemorrhage. These changes were severe in rats, given phenylbutazone alone, moderate in levamisole-treated animals, and mild in those given both drugs. Combination of levamisole with phenylbutazone not only decreased the congestion of gastric mucosa but also activated the gastric glands.

Analgesia↗
PubMed1986

Influence of monensin on fertility in rats.

Monensin was given orally to female rats at two dose levels (1.75 and 3.50 mg/kg body weight) over the period of 9-17 days of pregnancy where organogenesis of fetuses occur. The dams were killed on the nineteenth day of gestation and their fetuses were subjected to morphological, visceral and skeletal examination. The small dose of monensin increased the number of resorbed and dead fetuses and induced marked retardation in growth of viable fetuses, but visceral or skeletal defects in these fetuses were not seen. Large doses produced fetal resorption in all dams and no viable fetuses were delivered. Prolonged oral administration of monensin in male rats for 60 successive days at two dose levels, decreased the conception rate in non-treated females (mated with treated males) to 33.3% and 0% for the small and large doses, respectively. Both doses markedly decreased the weights of testicles, epididymides and seminal vesicles. The small dose of monensin caused oligospermia, whereas the large dose induced azospermia. Both doses decreased the activity of spermatogenic epithelium and caused degeneration in germ cells after histopathological examination of the testicles. It is concluded that monensin given during pregnancy to female rats is fetotoxic and when administered chronically to male rats, causes damage to the reproductive organs. The delayed effects of this drug are especially prominent.

Abnormalities, Drug-Induced↗
PubMed1985

Isolation of pigeon herpes encephalomyelitis virus in Saudi Arabia.

A virus was isolated from the brains of pigeons suffering from nervous disorders in different localities of the Eastern Province, Kingdom of Saudi Arabia. The new isolate caused a high morbidity, ranging from 33% to 50%, and a mortality rate which reached 40%. The virus produced pinpoint greyish pock lesions on the chorioallantoic membrane of embryonated hens' eggs and induced syncytial formation followed by rounding and lysis of the cells in chicken embryo fibroblast cultures. Virus infectivity was significantly reduced following treatment by 20% ether or chloroform. The isolated virus was identified as pigeon herpes encephalomyelitis virus by serum-neutralization, agar gel diffusion and fluorescent antibody staining techniques.

Animals↗
PubMed1984

The value of student-made models as learning aids in physiology.

In a new educational scheme introduced in Malta in 1978, university students spend half of the academic year studying and the other half as workers in various departments. During their work phase, students designed and made working models as teaching aids for the study of physiology. The value of these models was assessed on another group of students before they started their physiology course. These students completed a multiple choice questionnaire on three occasions: before and after having seen the models and after they had had them explained. In addition, they completed a questionnaire designed to elicit their views concerning these models. It was found that the models effectively improved knowledge with little staff involvement. The effectiveness of a model as an aid to learning was directly proportional to the degree of its appeal, but inversely proportional to its complexity in terms of stimulating factors. It is suggested that such models could help in teaching, compensating for shortage of staff, and that students' ability to produce teaching models should be wisely exploited.

Audiovisual Aids↗
PubMedDate not supplied

Antigenic relatedness of pigeon herpes encephalomyelitis virus to other avian herpesviruses.

Pigeon herpes encephalomyelitis virus (PHEV) was compared with seven avian herpesviruses for antigenic relatedness using monospecific antisera and the indirect fluorescent-antibody (IFA), agar-gel-immunodiffusion, and serum-neutralization tests. No antigenic relationship was detected between PHEV and Marek's disease virus, turkey herpesvirus, infectious laryngotracheitis virus, and duck enteritis virus. A common precipitating antigen was detected between the PHEV and pigeon herpesvirus (PHV), owl herpesvirus (OHV), and falcon herpesvirus (FHV). These four viruses also cross-reacted in the IFA test. Weak neutralizing activity was detected only between PHV antiserum and PHEV. These results suggest that the PHEV should be classified as a herpesvirus related to, but distinct from, the PHV-OHV-FHV group of viruses with which it shares common antigens.

Animals↗