Melatonin: data consistent with a role in controlling ovarian function.

FSH and LH excretion were correlated with melatonin excretion in consecutive daily urines obtained from a normal adult female (27 days), a normal 11-year-old girl (28 days), and an 8-year-old girl with idiopathic sexual precocity (30 days). Additionally pregnanediol-3-glucuronide (PG) excretion was determined in the urines of the adult female. Gonadotropin and PG excretion patterns of the adult female were those associated with a normal menstrual cycle.

The relative bioavailability of levonorgestrel and ethinyl estradiol administered as a low-dose combination oral contraceptive.

The relative bioavailability of levonorgestrel (LNG) and ethinyl estradiol (EE) administered concomitantly both as an oral tablet and as a solution was assessed in a randomized two-period crossover study in 24 healthy women. Serum concentrations were monitored for 96 h after each administration. The relative bioavailability (Fr) of LNG in the tablet with respect to the solution was 107%; thus the two formulations were bioequivalent with respect to LNG.

Follicle regulatory protein noncompetitively inhibits microsomal 3 beta-hydroxysteroid dehydrogenase activity.

A heat- and trypsin-labile follicular fluid protein (FRP) extracted from both human and porcine follicular fluid has been shown to modulate ovarian steroidogenesis. To further investigate the effects of FRP, its effect on the kinetics of 3 beta-hydroxysteroid dehydrogenase activity (3 beta-HSD) was evaluated in cell-free microsomal preparations from human placenta. Test fractions of follicular fluid protein were preincubated with placental microsomes followed by the addition of various substrate concentrations (pregnenolone + NAD).

Comparison of hepatic impact of oral and vaginal administration of ethinyl estradiol.

The pronounced hepatic impact of oral ethinyl estradiol has been attributed by some to its so-called first-pass effect through the liver as only some 40% of ingested ethinyl estradiol reaches the systemic circulation. Others believe that ethinyl estradiol exerts its hepatic effects because of its chemical composition, specifically its 17 alpha-ethinyl group. In an attempt to resolve this controversy, a study was undertaken to determine whether vaginal administration of ethinyl estradiol can selectively reduce the hepatic effects of oral ethinyl estradiol.

Plasma beta-endorphin concentrations prior to and during pregnancy, in labor, and after delivery.

Beta-Endorphin was measured by radioimmunoassay in peripheral plasma of nonpregnant women (58 +/- 2.4 pg/ml, n = 17, mean +/- SE), during the first trimester (47 +/- 2.4 pg/ml, n = 11), the second trimester (33 +/- 1.