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Biomedical subjects

R C Sharma

Publications and source records attributed to R C Sharma.

At least 163 records · Page 9Linked to original sources
PubMed1983

Structural and functional changes in epididymis following danazol plus testosterone enanthate administration in rabbit.

Danazol in combination with testosterone enanthate was administered to adult male rabbits to assess the structural and functional activity of epididymis. Seminal, biochemical and histological studies were made throughout the experiment. Sperm motility and count decreased markedly and at the end of treatment 75% of the animals became azoospermic. Seminal plasma GPC levels decreased significantly at 45 through 75 days of treatment. At 30 days of drug exposure, phospholipid, protein and sialic acid concentrations in caput epididymides were significantly low. Epididymal weight, phospholipid and protein contents markedly dropped in all segments of epididymides after 60 days of treatment. A reduction in epithelial and stereocilia height (caput and cauda), and lumen diameter (caput and corpus) was observed. Increase in intertubular stroma was evident. Lumen was devoid of spermatozoa at 60 days of treatment. All the changes were restored to normal 75 days after cessation of treatment. The combination therapy impaired the structural and functional integrity of the epididymis.

Animals↗
PubMed1983

New mutation (mmrA1) in Escherichia coli K-12 that affects minimal medium recovery and postreplication repair after UV irradiation.

After UV irradiation, Escherichia coli uvrA mutant cells show higher survival on minimal than on rich growth medium, i.e., they show minimal-medium recovery. This effect of rich growth medium on survival is not observed in a uvrA mutant carrying an mmrA1 mutation, and the uvrA mmrA strain showed the same survival rate on minimal and rich growth media as the uvrA strain did on minimal medium plates. The mmrA1 mutation was isolated as a hidden mutation from a uvrA polA mutant strain and shown to map at 84.3 min on the E. coli K-12 linkage map. In contrast to the uvrA strain, the repair of DNA daughter strand gaps was not inhibited in the uvrA mmrA strain by rich growth medium after irradiation. However, the uvrA and uvrA mmrA strains were similar in their ability to repair DNA when compared in minimal medium. These data are consistent with the idea that the mmr gene product is not involved directly in the repair of UV radiation-induced DNA damage, but rather allows rich growth medium to inhibit a portion of postreplication repair.

Chromosome Mapping↗
PubMed1981

Roles of the relA(+) gene and of 4-thiouridine in near-ultraviolet (344 nm) radiation inhibition of induced synthesis of tryptophanase in Escherichia coli B/r.

Near-ultraviolet radiation (near UV; 300-380 nm) is known to inhibit the induced synthesis of tryptophanase by tryptophan in Escherichia coli, showing an action spectrum similar to that for near-UV-induced growth delay. The present work shows that a relA mutant of E. coli B/r exhibits 50% as much monochromatic near-UV (334 nm) inhibition of tryptophanase induction as the wild type, and tht a mutant lacking 4-thiouridine, an unusual nucleoside in tRNA, exhibits greater than 10% as much inhibition of tryptophanase induction. These findings indicate that 4-thiouridine is almost the sole chromophore for this effect in E. coli B/r, but that only 50% of the effect operates by a mechanism utilizing the relA(+) gene product; growth delay appears not to be primarily involved.

Enzyme Induction↗
PubMed1979

Heterogeneity of failure of visual acuity in Graves' disease.

The eye manifestations of Graves' disease are usually mild and self-limiting. Occasionally they follow a progressive course leading to visual loss and total blindness. The ocular manifestations bear no relationship to the metabolic state and may appear before, during or after onset of thyrotoxicosis. Characteristically they become evident at about the time of onset of hypermetabolism. Various factors responsible for the failure of visual acuity are discussed with case illustrations.

Adult↗