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Biomedical subjects

S Das

Publications and source records attributed to S Das.

At least 703 records · Page 39Linked to original sources
PubMed1978

Regulation of expression and chromosomal subunit conformation of avian retrovirus genomes.

We have investigated the copy number, chromosomal subunit conformation and regulation of expression of integrated avian retrovirus genomes. Our results indicate that there are approximately two copies of the endogenous viral genomes (RAV-O) per haploid cell genome in uninfected chick embryo fibroblasts (CEF) and red blood cells (RBC). The copy number and subunit conformation (as measured by DNAasel sensitivity) of the RAV-O genomes are independent of the level of expression of these viral DNA sequences. In cells isolated from embryos of the V+, gs-chf- and gs+chf+ phenotypes, approximately one of the two viral genomes is in a DNAase l-sensitive conformation. Upon infection with an exogenous Rous sarcoma virus (PR-RSV-C), one new viral genome is integrated per haploid CEF genome. The newly integrated RSV genome is completely sensitive to DNAase l, and the subunit conformation of the endogenous viral genomes is not altered by the integration of additional exogenous proviruses. Both the endogenous and newly integrated exogenous viral genomes are present in "nu-body" structures, and the selective sensitivity of these proviral DNA sequences to DNAase l is maintained in isolated nucleosomes. Our experiments revealing the DNAase l sensitivity of one of the two RAV-O genomes in gs-chf-CEF led us to reexamine the level of viral specific RNA in CEF of various GS genotypes. We find that GS/GS CEF contain approximately 100 copies of viral RNA per cell, gs/gs CEF contain no detectable viral RNA, and the heterozygote GS/gs CEF contain approximately 50 copies of viral specific RNA per cell. These results suggest that the GS gene controls production of RAV-O RNA sequences in CEF in a "cis" fashion. In RBCs, however, the expression of the RAV-O genome is independent of the GS gene, with both GS/GS and gs/gs RBCs containing roughly equivalent amounts of viral specific RNA. Our results suggest that the chromosomal structure of the endogenous viral genes is independent of the GS gene, and that the GS gene is cis-acting and tissue-specific.

Avian Leukosis Virus↗
PubMed1978

Responses of gill to various changes in salinity in fresh water teleost Colisa fasciatus (Bl. and Schn.).

In the present study the effects of different osmotic conditions have been observed on the gills of a fresh water air breathing teleost Colisa fasciatus. 1. In control fishes two types of specialised cells (mucous gland and mast cells) are found in the gill. There is no special type of "chloride cell". None of the cells give AgNO3/HNO3 test. The size of the mucous cells varies from 5.50 micrometer to 5.94 micrometer. 2. After distilled water treatment, the epithelium is severely swollen and at some places completely desquamated from the lamellae, leaving only the blood capillaries and supporting pilasler cells, due to endosmosis. 3. After 40% salt water treatment the exhaustive stages in mucous glands and marked shrinkage of the entire respiratory epithelium is observed. The excess of salt causes exosmosis resulting in death of the fishes. 4. After 8% salt water treatment the number and the size of mucous prodicing cells of treated fish increases approximately four times as compared to controlled fishes during the first week of adaptation. In case of one month treated fish the gill surface area increases extensively and is occupied by the mucous cells. These mucous producing cells are AgNO3/HNO3 positive indicating their transformation into so called "chloride cells". The size of mucous cell increases upto 19.63 micrometer.

Adaptation, Physiological↗
PubMed1977

The use of a silicone gel prosthesis in the treatment of post-prostatectomy incontinence.

Eighty-three patients with post-prostatectomy urinary incontinence were treated by silicone gel prostheses implanted over the bulbous urethra. The prosthesis provides continence by passively increasing the urethral resistance. Successful results were achieved in 72% of patients. The mechanism of post-prostatectomy incontinence and the development of anti-incontinence surgery is briefly reviewed.

Humans↗
PubMed1977

The Small-Carrion prosthesis for male impotency.

Small-Carrion penile prostheses were implanted in 61 patients who have been followed for 3 to 21 months. Of these 61 patients 55 have achieved satisfactory results, with a return of normal sexual function. The importance of preoperative evaluation and preparation is stressed.

Adult↗
PubMed1977

Duplication of the male urethra.

Our experience with 4 male subjects with accessory urethras is reported. The anatomic types, clinical presentations and treatment modalities of urethral duplication are discussed. Our scrutiny of all cases reviewed in the literature led us to classify patients into 3 types, depending upon the anatomic and embryologic features. Type 1 is a complete accessory urethra arising from a separate or confluent opening within the bladder and extending to an external orifice. Type 2 includes accessory urethras that arise from the primary urethra and may or may not extend to a distal orifice. Type 3 is the most unusual anomaly, in which 1 of the duplicated urethras arises from the bladder or proximal urethra and opens onto the perineum.

Adult↗