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Biomedical subjects

B Sivakumar

Publications and source records attributed to B Sivakumar.

At least 55 records · Page 3Linked to original sources
PubMed1979

Pharmacokinetics of norethindrone in Indian Women.

Pharmacokinetics of norethindrone (NET) was evaluated in eleven women belonging to a low socio-economic group and in five womem belonging to the high socio-economic group after the administration of an oral dose of 0.35 mg NET minipill on an empty stomach. Blood samples were collected at different intervals of time over a period of 24 hours. Plasma NET was estimated by radioimmunoassay. In all women, peak levels of NET occurred within 1-2 hours and a semi-log plot of plasma NET levels showed a biexponential decline. The half-life of plasma NET clearance was relatively shorter in women of low socio-economic group with poor nutritional status as indicated by anthropometric indices, as compared to that in well nourished women of high socio-economic group. There was a significant positive correlation between weight/(height) 2x 100 index on the one hand and t1/2 (beta) on the other in all the women studied, thereby suggesting a role for nutritional status in the metabolic handling of NET.

Absorption↗
PubMed1979

The rabbit as an animal model to study pharmacokinetics of norethindrone in women.

The pharmacokinetics of norethindrone (NET) were studied in adult female rabbits and rhesus monkeys with a view to developing an animal model closely resembling humans in the handling of NET. Plasma levels of NET were determined in rabbits and monkeys after administering either labelled NET or a NET minipill. Pharmacokinetic parameters were evaluated by using a two-compartment open model and by graphical and regression analysis of plasma NET data. In rabbits, the drug absorption was found to be rapid and NET peak levels were attained within 0.5 to 1.0 hour. The clearance half-lives were 1.3 hours for 'alpha' and 10.0 hours for 'beta'. In monkeys, plasma NET values showed an inconsistent pattern and the approximate t 1/2 was found to lie between 4 and 6 hours. The observed pharmacokinetics of NET in rabbits rather than in monkeys were closer to those in humans. On this basis, it would appear that the rabbit is a suitable animal model for studying effects of nutritional factors on the pharmacokinetics of NET.

Animals↗
PubMed1977

Evaluation of a microspectrofluorimetric method or serum vitamin A.

A microspectrofluorimetric method for vitamin A was compared with spectrophotometric and trifluoroacetic acid-colorimetric procedures. Values obtained by the fluorimetric method showed a high degree of correlation with those obtained by other standard procedures. However, it was found that the fluorimetric method yielded values which were several-fold higher than those obtained with the spectrophotometric method when sera from pregnant women were tested. The fluorescence from sera of pregnant subjects showed a triphasic decline even when the samples were stored at --20 degrees C.

Child↗
PubMed1976

Circulating levels of immunoreactive parathyroid hormone in endemic genu valgum.

Circulating levels of immunoreactive parathyroid hormone (PTH) were estimated in fifteen normal subjects and twenty-five subjects suffering from the skeletal fluorosis, ten of whom had associated endemic genu valgum. Levels of PTH were high in all the subjects with fluorosis as compared to normals, but among fluorosis subjects, those who had endemic genu valgum had values strikingly higher than those without. It is suggested that secondary hyperparathyroidism may have a significant role to play in the pathogenesis of osteoporosis seen in patients with endemic genu valgum.

Adolescent↗
PubMed1975

Absorption of vitamin A in children with ascariasis.

Absorption of labelled vitamin A was studied in normal children and in children with round-worm infestation. Absorption of the vitamin was significantly low in children with ascariasis. In two subjects, in whom the studies were repeated, absorption of vitamin A was significantly increased after antihelminthic treatment. These results suggest that ascariasis may aggravate vitamin A deficiency by interfering with the absorption of the vitamin.

Acetates↗