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Biomedical subjects

K R Bhat

Publications and source records attributed to K R Bhat.

15 recordsLinked to original sources
PubMed2000

Role of poly(ADP-ribose) polymerase (PARP) in DNA repair in sulfur mustard-exposed normal human epidermal keratinocytes (NHEK).

We previously reported that, in normal human epidermal keratinocytes (NHEK) cultures exposed to the alkylating compound sulfur mustard (bis-(2-chloroethyl) sulfide, HD, 0.3-1 mM), there is a rapid (< or =1 h) activation (100% above unexposed control) of the DNA repair enzyme DNA ligase I (130 kD) followed by a first-order decay (1-5 h). The DNA ligase activation is accompanied by a time-dependent (0.5-4 h) and significant DNA repair. Inhibition of another putative DNA repair enzyme, poly(ADP-ribose) polymerase (PARP), by using 3-amino benzamide does not affect DNA ligase activation following HD exposure, but increases the half-life of the activated enzyme threefold. To examine the role of PARP in HD-induced DNA ligase activation and subsequent DNA repair, we conducted studies using cultured keratinocytes in which the level of PARP had been selectively lowered (> or =85%) by the use of induced expression of antisense RNA. In these cells, there was no stimulation of DNA ligase up to 3 h, and a small stimulation (ca. 30% above unexposed control at 5-6 h after HD exposure. A time-course (0.5-6 h) study of DNA repair in HD-exposed PARP-deficient keratinocytes revealed a much slower rate of repair compared with HD-exposed NHEK. The results suggest an active role of PARP in DNA ligase activation and DNA repair in mammalian cells, and also indicate that modulation of PARP-mediated mechanisms may provide a useful approach in preventing HD toxicity.

Cell Culture Techniques↗
PubMed1996

Significance of lymphocytic sister chromatid exchange frequencies in ovarian cancer patients.

Very few studies report the analysis of sister chromatid exchanges in ovarian cancer patients. We tested the null hypothesis that SCE frequency increases with the advancing stages of ovarian cancer and follows a Poisson distribution. As controls we examined age- and sex-matched healthy volunteers who had no such past history. An increased average SCE frequency was observed in ovarian cancer patients (6.34 +/- 0.09) vis-à-vis controls (4.47 +/- 0.12). Further, the data also suggested a stage-wise increase in the SCE frequency.

Adult↗
PubMed1983

Vascular changes in nerves in experimental leprosy--an ultrastructural study.

Ultrastructural observations made on the blood vessels of nerves in CBA/J mice with experimentally produced M. leprae infection revealed cytoplasmic filamentous structures along with large sized vacuoles in the endothelial cells and reduplication of peripericytal basement membranes in the 6-9 months of infection. In animals with late infection of 9-15 months duration, the endothelial cells presented foamy appearance caused by an increase in the number of vacuoles. These findings are suggestive of degenerative changes in the endothelial cells probably due to circulation of noxious substance in the blood stream.

Animals↗
PubMedDate not supplied

Identification of risk factors for specific subsites within the oral and oropharyngeal region--a study of 647 cancer patients.

Studies on site specific risks for oral cancers are few. Present investigation explores the possible role of human sociodemographic factors in causing oral cancer. Majority of patients had poor oral hygiene (85.5%) and belonged to 51-60 years age group (35.7%). Most of the subjects were agriculture workers (30.3%). Tongue and floor of mouth included majority of the affected sites (77.2%). Male to female ratio was highest for tonsil (32.3%) but differed marginally for other subsites. Majority of females used tobacco (81%) while males users of tobacco, alcohol and smoking reported in nearly equal proportions. Tobacco and smoking were found as primary risk factors for several intraoral subsites. However, for tongue, palate and lip no risk factor could be identified from given patients' characteristics. In general, tobacco posed high risk for buccal mucosa and alveolus in comparison to other subsites. Smoking affected tonsil and floor of mouth more than other sites. Alcohol posed more risk for buccal mucosa and floor of mouth than tongue.

Adult↗
PubMedDate not supplied

Septo-optic dysplasia (case report).

Septo optic dysplasia is a rare developmental anomaly involving bilateral optic nerve hypoplasia, midline anomalies of the brain and hypothalamo-pituitary dysfunction. A case of septo-optic dysplasia with pituitary dwarfism, optic nerve hypoplasia and absent septum pellucidum is reported.

Child↗