Sex reversal in wrasses. I. Uptake of testosterone by the gonads and the central nervous system and its aromatization in the CNS of Thalassoma duperrey (Teleostei: Labridae).

3H-Labelled testosterone, injected into the peritoneal cavity of T. duperrey is taken up by the central nervous system and the gonads. In the brain maximal uptake occurs within 1 to 2 h whereas maximal uptake in the gonads takes place within 1/2 to 1 h.

A review of parenteral sustained-release naltrexone systems.

The ideal naltrexone sustained-release delivery system should be easy to inject or implant, not cause adverse tissue reaction, release the drug at a relatively constant rate for at least 30 days, and biodegrade within a short time afterwards. Mechanisms which can be used for sustaining drug release include reducing solubility and surface area, coating, encapsulation and microencapsulation, complexation, binding and hydrophilic gelation. Drug release from such systems is controlled by diffusion through a barrier/film, diffusion from a monolithic device, erosion of the surface, hydrolysis, ion exchange, biodegradation, or a combination of these.

Suppression of immune responses by progesterone.

Biodegradable sustained release progesterone-collagen dosage from prolonged significantly the survival of hamster-rat and mico-mice skin grafts. The duration of immune response suppression could be correlated to progesterone concentration in the collagen matrix. Collagaen sponges, sponges containing pregnenolone, estradiol, or cortisol were not effective in prolonging skin graft survival.

Preferential uptake of estradiol in the pituitary and hypothalamus of mature male rats in the presence of testosterone.

Simultaneous intravenous injection of 3H-estradiol and 14C-testosterone into adult male rats resulted in significant concentration of both labels in the blood and the diencephalon 2 h after the injection. In the pituitary--hypothalamic area only estradiol derived radioactivity could be detected, while testosterone derived 14C label was not found. The results are interpreted to indicate that in males estradiol, not testosterone, may provide the homeostatic balance between the gonads and the hypothalamo-pituitary axis.

Sustained-release hormonal preparations XV: release of progesterone from cholesterol pellets in vivo.

Progesterone-sterol pellets were made that porvided a zero-order release of progesterone for 80 days. 4-(14)C-Progesterone was used to measure the release in vitro and in vivo. The dissolution rate in vitro (distilled water as the desorbing medium) for progesterone-cholesterol (59:41 w/w) and the progesterone-beta-sitosterol (47:53 w/w) pellets was 72 microng/100 mm2/24 hr.

Plasma concentrations of ethynyl oestradiol and norethindrone after oral administration to women.

Plasma concentrations of ethynyl oestradiol and norethindrone in women were measured by radioimmunoassays after oral administration of 50 microng and 1000 microng respectively. The maximum values were obtained 1 h after administration. The calculated half-life was 6 1/2 h for ethynyl oestradiol and 7 h for norethindrone.

Radioimmunoassay of norethindrone (17 alpha-ethynyl-17 beta-hydroxy-4-estren-3-one) and ethynyl-estradiol (17 alpha-ethynyl-1,3,5, (10)-estratien-3, 17 beta-diol). Application to human plasma determination of norethindrone after oral administration of this steroid.

The experiment conditions for the evaluation of Norethindrone (17 alpha-Ethynyl-17 beta-hydroxy-4-estren-3-one, NET) and Ethynyl-estradiol (17 alpha-ethynyl-1, 3, 5 (10) estratrien-3, 17 beta-diol, EE) by radioimmunoassay are described. A minimal quantity of 25 pg of these two steroids could be evaluated using different reduced metabolites of NET, very little cross reaction is observed with 200 pg of these metabolites. No effect was observed with estradiol for the EE-antiserum.