Pritam S. Verma

Evidence of Higher Ethynylestradiol Blood Levels in Human Hypertensive Oral Contraceptive Users

These studies were designed to investigate the differences in blood plasma levels of ethynylestradiol (EE2) in women who developed hypertension while taking combined estrogen and progesterone oral contraceptives (OCs) and in normotensive OC users. Blood samples were collected in heparinized tubes 10 hours after OC ingestion, the plasma was separated, and EE2 was measured by radioimmunoassay. The results showed significantly higher plasma levels of EE2 in the hypertensive OC users as compared with the levels in normotensive OC users (P less than 0.01). In another study, blood samples from hypertensive and normotensive OC users were obtained for 3 consecutive days at fixed intervals following OC ingestion, and plasma levels of EE2 were measured. The results showed consistently higher EE2 blood levels during this 3-day period in the hypertensive subjects (P less than 0.01). It is postulated that the higher blood levels of EE2 in hypertensive OC users result from either decreased metabolism or excretion of synthetic estrogens.

Radioimmunoassay of pyridostigmine in plasma and tissues

A sensitive and specific radioimmunoassay is reported for the cholinergic agent, pyridostigmine. Antibodies were raised in rabbits against a conjugate of pyridostigmine and bovine serum albumin. The assay can detect as little as 2.5 ng/ml of drug directly in plasma and tissue homogenates. Structurally similar compounds and major metabolites are not recognized by the antibody. The specificity of the antibody has been confirmed by utilizing high pressure liquid chromatography. Plasma concentration-time profiles and tissue distribution of the drug were determined by this method in rat after intramuscular administration of pyridostigmine.

A Radioimmunoassay for Norethindrone. II. Plasma Levels in Hypertensive and Nomotensive Oral Contraceptive Users

Abstract A sensitive radioimmunoassay for measurement of norethindrone (N) in blood plasma has been developed. The coefficient of variation within the assay and between assays was 7 and 13.5% respectively. The procedural blanks were negligible, and recovery was approximately 81.8%. Blood plasma levels of N in 20 normotensive and 6 hypertensive women who were ingesting oral contraceptives (OCs) were measured, and the results indicate that the subjects who became hypertensive while taking OCs had significantly higher levels of N compared with normotensive OC users (p < .001).

Simultaneous Determination of Aldosterone and Deoxycorticosterone in Human Plasma by Radioimmunoassay

Abstract A simple, sensitive and reliable radioinmunoassay method for the shltaneous determination of aldosterone and deoxycorticosterone (Doc) in human plasma has been developed. The method involves extraction of plasma with methylene chloride followed by Sephadex LH-20 column chromatography prior to assay. The method is sensitive, and precision and accuracy are satisfactory. Plasma aldosterone and DOC concentration measured under different conditions are in agreement with published data.

Effect of in vitro incorporation of prostanoid precursors, superoxide radical and hydrogen peroxide on platelet function

The level of cyclic adenosine monophosphate (cAMP) in human platelets is known to be an important regulator of platelet function. The polyunsaturated fatty acids (PUFA) dihomo-gamma-linolenic acid (DHLA), and eicosapentaenoic acid (EPA), precursors of the prostaglandin (PG) 1 and 3 series respectively, were studied for their ability to stimulate platelet cAMP and/or PGE1 levels, and to inhibit platelet aggregation (PAg). Incubation of washed platelets (1 x 10(8)/ml) with 125 microM DHLA increased intraplatelet levels of PGE1 from 197 +/- 7 to 1622 +/- 9.7 picograms/10(8), cAMP from 3 +/- 0.8 to 31 +/- 1.9 picomoles/10(8), and inhibited collagen-induced PAg. Addition of 1 mumole of xanthine per unit of xanthine oxidase (a superoxide radical generating system) to the incubating medium potentiated the effects of both fatty acids, whereas 240 microM Hydrogen Peroxide (H2O2) inhibited these effects. These results suggest that: (1) DHLA may be more effective in inhibiting PAg than EPA, which has been reported to reduce the incidence of coronary diseases in some human populations; (2) That superoxide radical may activate the platelet cyclooxygenase system to increase lipid peroxidation of these PUFA prostanoid precursors and may result in the inhibition of PAg, whereas H2O2 may have an opposite effect.