Luteinizing hormone (LH) is released by the pituitary in discrete pulses. In the monkey, the appearance of LH pulses in the plasma is invariably associated with sharp increases (i.e, volleys) in the frequency of the hypothalamic pulse generator electrical activity, so that continuous monitoring of this activity by telemetry provides a unique means to study the temporal structure of the mechanism generating the pulses. To assess whether the times of occurrence and durations of previous volleys exert significant influence on the timing of the next volley, we used a class of periodic counting process models that specify the stochastic intensity of the process as the product of two factors: 1) a periodic baseline intensity and 2) a stochastic regression function with covariates representing the influence of the past. This approach allows the characterization of circadian modulation and memory range of the process underlying hypothalamic pulse generator activity, as illustrated by fitting the model to experimental data from two ovariectomized rhesus monkeys.

We investigated the potential pituitary origin of gonadal insufficiency in hemochromatosis. Gonadotropin secretion was studied in seven patients with hemochromatosis and hypogonadism, before and after chronic pulsatile GnRH therapy. Pulsatile LH secretion was studied before (sampling every 10 min for 6 h) and after 15-30 days of chronic pulsatile GnRH therapy (10-12 micrograms per pulse). Prior to GnRH therapy, all the patients had low serum testosterone, FSH and LH levels. LH secretion was non-pulsatile in four patients, while a single pulse was detected in the remaining three. Chronic pulsatile GnRH administration did not increase serum testosterone levels; similarly, serum LH levels remained low: neither pulse frequency nor pulse amplitude was modified. We conclude that hypogonadism in hemochromatosis is due to pituitary lesions.

To assess the role of androgens in gonadotropin regulation in women, we studied the effects of a pure nonsteroidal antiandrogen, Anandron (Cassenne, Paris, France). Nine normally cycling women (group 1) with acne and/or seborrhoea and nine patients with polycystic ovarian disease (PCOD) (group 2) received Anandron (100 mg twice a day) and a placebo. Both treatments were administered orally, in a cross-over randomized design, for two consecutive cycles (group 1) or months (group 2) separated by one cycle or 1 month. Luteinizing hormone (LH) pulse frequency and amplitude (cluster analysis), basal and gonadotropin-releasing hormone (GnRH)-stimulated plasma LH/follicle-stimulating hormone (FSH) levels were determined on day 5 of each treatment or placebo cycle. On days 5, 10, 20, and 24 of each cycle or month, plasma estradiol (E2), estrone (E1), testosterone (T), dihydrotestosterone (DHT), androstenedione (A), dehydroepiandrosterone sulfate (DHAS), sex hormone-binding globulin (SHBG) levels, and urinary androstanediol glucuronide (3 alpha-diol G) were measured. Plasma progesterone (P) levels were determined on days 20 and 24 of each cycle (group 1) and on days 5, 10, 20, and 24 (group 2). In both groups, seborrhea and acne decreased markedly within the first month and practically disappeared after 2 months of Anandron treatment. No adverse side effects were reported. None of the normal patients had any disturbance of menstrual cycles as assessed by basal body temperature shift, ultrasonography, and plasma P levels. In PCOD patients, cycles remained anovulatory.(ABSTRACT TRUNCATED AT 250 WORDS)

[d-Ala1]-Peptide T amide is an octapeptide presently undergoing clinical evaluation as a potential agent for the treatment of AIDS. As a part of studies aiming at obtaining an oral delivery form of the peptide, its stability towards α-chymotrypsin was examined. The peptide was found to be rapidly degraded by this pancreatic enzyme, the degradation being due to cleavage of the Tyr-ThrNH2 bond. At pH 7.4 and 37°C the peptide showed a Km value of 1.3 × 104 M, a kcat value of 560 min−1 and a specificity constant (kcat/Km) of 4.3 × 106 M−1 min−1. At physiological concentrations of α-chymotrypsin and at pH 6.0–7.4 the half-life of degradation of the peptide was calculated to be less than 5 s. It is thus concluded that a means to protect [d-Ala1]-Peptide T amide against cleavage by α-chymotrypsin is an absolute requirement for the development of an orally absorbable product. The peptide proved highly stable toward aminopeptidase as well as in human plasma.