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Biomedical subjects

S Ramakrishnan

Publications and source records attributed to S Ramakrishnan.

At least 271 records · Page 15Linked to original sources
PubMed1976

Isoimmunization against human chorionic gonadotropin with conjugates of processed beta-subunit of the hormone and tetanus toxoid.

The immunogenicity of the conjugate prepared from "processed" beta-subunit of human chorionic gonadotropin (choriogonadotropin, HCG) and tetanus toxoid has been studied in animals and a human subject. The conjugate elicited the formation of high-affinity (Ka = 10(9)-10(11) M-1) anti-HCG and anti-tetanus antibodies. On primary immunization, the antibody, response lasted for several months. Repeat injection of the conjugate in the declining phase of antibody titers produced a booster response without a lag period. The antibodies reacted with the beta-subunit of HCG and the complete HCG molecule but were devois of significant crossreactivity with human growth hormone, placental lactogen, follicle-stimulating hormone, thyroid-stimulating hormone, and luteinizing hormone at tonic and surge levels. The antibodies were competent for neutralizing the biological activity of HCG in the mouse uterine weight gain assay, the ventral prostate weight gain assay, and the radioligand assay for binding of 125I-labeled HCG to receptors on corpus luteum. HCG (5000 international units) administered to an immunized subject was completely bound by circulating antibodies. Administration of HCG (in contrast to conjugate) was without booster effect on anti-HCG titers.

Animals↗
PubMed1975

Indirect assessment of hydroxymethylglutaryl-CoA reductase (NADPH) activity in liver tissue.

We describe an indirect method for assessing variation in 3-hydroxy-3-methylglutaryl-coenzyme A reductase (NADPH) activity in liver tissue. 3-Hydroxy-3-methyglutaryl-CoA and mevalonate concentrations in the tissue homogenate are estimated in terms of absorbances and the ratio between the two is taken as an index of activity of the enzyme, which catalyzes the conversion of 3-hydroxy-3-methylglutaryl-CoZ to mevalonate. The ratio increases under conditions in which activity of this enzyme in liver reportedly decreases (e.g., fasting, cholesterol feeding) and decreases under conditions in which the activity of this enzyme reportedly increases (e.g., Triton injection, phenobarbital treatment). We assessed the magnitude of hepatic cholesterogenesis in intact male albino rats by using [1,2-14C] acetate, in fed controls, fasted, cholesterol-fed, Triton-treated, and phenobarbital-treated. The ratio, 3-hydroxy-3-methylglutaryl-CoA/mevalonate was estimated in liver tissue for all the above groups. The method is simple, reproducible, and does not require any unusual chemicals.

Alcohol Oxidoreductases↗