PubMed Health⌕ Search

Biomedical subjects

M A Ibrahim

Publications and source records attributed to M A Ibrahim.

At least 73 records · Page 4Linked to original sources
PubMed1978

Characterisation of ribosomes from drug resistant strains of Schizosaccharomyces pombe in a poly U directed cell free protein synthesising system.

Mutants of Schizosaccharomyces pombe were isolated as resistant either to trichodermin or to anisomycin. Growth tests showed that the majority of mutants isolated were cross resistant to both drugs and also to cycloheximide. A limited genetic analysis showed that mutants at least four loci, tri3, tri4, ani1 and ani2, had this phenotype as was also the case for mutants at three cycloheximide resistant loci, cyh2, cyh3 and cyh4 reported previously (Ibrahim and Coddington, 1976). Allelism tests showed that the tri3, ani2 and cyh4 strains were allelic. A mutant at another trichodermin resistant locus, tri5, was cross resistant to anisomycin but sensitive to cycloheximide. Ribosomes from wild type and selected strains were analysed in a poly U directed cell free protein synthesising system. Three strains, cyh1-C7, ani1-F1 and tri-N15 (probably a tri5 allele) possessed ribosomes which were more resistant than the wild type to the drugs used in their isolation. In each case the site of the resistance was in the 60S subunit. Ribosomes from the cyh2, cyh3 and cyh4 strains were as sensitive to cycloheximide as those from wild type.

Anisomycin↗
PubMed1978

Physician opnions on the use of antibiotics in respiratory infections.

To investigate the feasibility of establishing standards of care based on a broad consensus, a questionnaire concerning the management of signs and symptoms of common respiratory infections in infants was given to a national sample of pediatric infectious disease specialists, general pediatricians, and family physicians. There was significant disagreement (p less than .01) among the three groups of physicians in 15 of the 18 clinical situations concerning the appropriateness of prescribing antibiotics. Whenever there was disagreement, the family physician group was most inclined and the infectious disease group least inclined to favor antibiotics therapy. More than 75% of each group favored antibiotics in the same situation in only three instances. These results suggest that it may be difficult to set widely accepted standards for the evaluation of medical care where there are such differences of opinion.

Age Factors↗
PubMed1978

Genetical studies on revertants to sensitivity from a cycloheximide resistant strain of Schizosaccharomyces pombe.

Six UV induced cycloheximide-sensitive revertants were isolated from the cyh1-C7 strain of Schizosaccharomyces pombe which is resistant to cycloheximide. In all cases reversion to sensitivity was due to a forward mutation in a second suppressor gene. Genetical analysis showed that at least two genes, designated scr1 and scr2 (scr=suppression of cycloheximide resistance) were involved. Both scr1 and scr2 suppressed the resistance of six independently isolated alleles at the cyh1 locus. They had no effect on two known nonsense mutations in the ade7 locus. The cyh1-C7 strain has an altered 60S ribosomal protein which can be detected by two-dimensional polyacrylamide gel electrophoresis. In two suppressed strains, cyh1-C7 scr1 and cyh1-C7 scr2, the original altered protein was present. However no further ribosomal protein differences were observed which could be correlated with the presence of the scr genes. Both scr mutations conferred cold sensitivity on the organism indicating that they were of the missense type. Hence it seems certain that scr1 and scr2 are not mutations in tRNA genes leading to either nonsense or missense suppression. There is however no direct evidence that they code for ribosomal proteins and exert their effect on cyh1-C7 at the ribosomal level.

Cycloheximide↗