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Biomedical subjects

A M Medhat

Publications and source records attributed to A M Medhat.

6 recordsLinked to original sources
PubMed1996

Synteny mapping in river buffalo.

The cosegregation of ten coding loci has been investigated, in a panel of 37 somatic cell hybrids resulting from the fusion of a hamster cell line and river buffalo lymphocytes, by use of Southern hybridization technique. Five syntenic groups, TCRB-PGY3, ASS-ABL, FUCA1P-CRYG, MBP-YES1, and CGN1-ACTA1, previously assigned to cattle as U13, U16, U17, U28, and U29 respectively, were also found to be syntenic in buffalo. Based on the extensive syntenic conservation and banding homology between cattle and river buffalo, comparative mapping predicts the localization of these syntenic groups on river buffalo Chromosomes (Chrs) :BBU7, BBU12, BBU2q, BBU22, and BBU4q respectively as they have been previously localized on cattle Chrs BTA4, BTA11, BTA2, BTA24 & BTA28.

Animals↗
PubMed1995

Cloning of the gene for phosphoglycerate kinase from Schistosoma mansoni and characterization of its gene product.

As molecules on the surface or associated with the outer covering (tegument) of Schistosoma mansoni are a major focus as potential vaccine candidates, affinity purified antibodies which are specific to the tegumental antigens were used to immunoscreen a lambda gt11 S. mansoni cercarial cDNA library. One of the identified clones was found to encode the glycolytic enzyme phosphoglycerate kinase (PGK, EC 2.7.2.3). The 1.5-kb cDNA clone has a single open reading frame encoding 416 amino acids and exhibits over 60% identity to PGKs from a number of eukaryotic species. Recombinant S. mansoni PGK (SmPGK) was overexpressed in Escherichia coli, purified, and shown to have PGK enzyme activity. Native protein affinity purified from S. mansoni adult worms was shown by microsequencing to have the same amino-acid sequence as deduced from the cDNA sequence, thus confirming the cDNA clone we identified encodes S. mansoni phosphoglycerate kinase. Antibodies localize the native SmPGK to various tissues including the tegument of 3-h schistosomula and 42-day adult worms.

Amino Acid Sequence↗
PubMed1991

Soybean and ascorbate feeding in experimental carcinogenesis: immunological studies.

Soybean and/or sodium ascorbate have been demonstrated to have protective effects against carcinogenicity of the nitrosamine precursors dibutylamine and sodium nitrite in rats. Some immunological aspects of the cellular and humoral compartments of the immune system were investigated in this experimental model. The parameters chosen for the study were the lymphocyte transformation test, migration inhibition test, the demonstration of Fc and Fc plus complement receptors on the lymphocyte surface (EA and EAC rosette-forming test), and the determination of total serum proteins and their fractions. The results indicated that dibutylnitrosamine can be formed in vivo from its precursors dibutylamine and sodium nitrite, and that it affects the immune system of rats which showed an immunosuppressed state present as depressed cellular and humoral immunity. The protective role of soybean and/or ascorbate against carcinogenicity of dibutylamine and sodium nitrite was demonstrated by the absence of tumor formation. These agents were found to be capable of increasing the defense mechanism of rats by enhancing both cellular and humoral immunity in the presence of the carcinogenic nitrosamine precursors dibutylamine and sodium nitrite.

Animals↗
PubMed1982

A new antitumour substance, 7-oxabicyclo (2.2.1)-5-heptene-2,3-dicarboxylic anhydride.

7-Oxabicyclo(2.2.1)-5-heptene-2,3-dicarboxylic anhydride has been found to possess antitumour activity against Ehrlich ascites carcinoma cells. The tumour cells incubated with the drug showed a decrease in the viable counts and cell proliferation. These effects were confirmed by in vivo studies in Swiss albino mice. The compound has a direct cytotoxic effect on the tumour cells. Vacuolization and disruption of the cytoplasm accompanied by unequal nuclear division and scattered chromosomes were recorded. In addition, 250 and 10 mg/kg were found to be the MTD and MED respectively. A dose of 25 mg/kg injected i.p. for 5 consecutive days in the tumour-transplanted animals caused a significant increase in their survival period. The compound has been shown to have a significant inhibitory effect on the DNA and RNA biosynthesis of EAC cells after 3 hr of administration; the protein biosynthesis was less affected. Meanwhile, the cellular contents of these metabolites were significantly reduced.

Animals↗
PubMedDate not supplied

Identification and characterization of Schistosoma mansoni p17.7, a cyclophilin.

Antibodies affinity purified against tegumental components of schistosomula were used to screen a Schistosoma mansoni lambda gt11 adult worm cDNA expression library. One of the reactive clones was determined by sequence analysis to encode a protein homologous to cyclophilins of other species, in particular cyclophilin A. The 0.8-kb cDNA clone contained an open reading frame of 483 nucleotides which corresponds to a translation product of 161 amino acids with a deduced molecular size of 17.7 kDa. We have chosen to designate this clone as S. mansoni p17.7 (Smp17.7). The overexpressed and purified recombinant Smp17.7 (rSmp17.7) was demonstrated to possess peptidylprolyl cis-trans isomerase (PPIase) or rotamase activity typical of cyclophilins. Western blot analysis of Nonidet P-40 and a total soluble extract of adult schistosomes probed with affinity-purified antisera to rSmp17.7, demonstrated the presence of this protein in the parasite. Immunofluorescence studies using the purified antisera indicates a localization in various tissues including the tegument and the gut. As cyclophilin is able to interact with cyclosporin A (CsA), which has been shown to be antischistosomal in mice infected with S. mansoni, the characterization of this S. mansoni cyclophilin homologue may allow a better understanding of the schistosomicidal nature of cyclosporin A and lead to a novel strategy of therapy for schistosomiasis.

Amino Acid Isomerases↗