When doses of progestin used commercially are administered to synchronize the stage of the estrous cycle among bovine females, fertility is reduced compared with that of untreated controls. The reduced fertility that results from the use of progestin based estrus synchrony regimens is associated with the development of persistent ovarian follicles. Persistent ovarian follicles develop as a resu...

Mouse embryos at day 9 of development were cultured for 24 to 42 h in 50% fetal calf serum and 50% Waymouth's medium containing 0.5 micrograms/ml insulin supplemented with various amounts of progesterone and estradiol-17-beta. Unmodified medium contained approximately 0.2% of the normal maternal blood levels for that stage of pregnancy. The addition of 1 X 10(-7)M progesterone to the medium bro...

The effect of 17 beta-estradiol on cytoplasmic thymidine kinase activity was studied in MCF-7, a human breast cancer cell line in culture which responds to estrogens with an increase in the rate of growth. Levels of 17 beta-estradiol which maximally stimulate [3H]thymidine incorporation into DNA also maximally stimulate thymidine kinase activity. The Vmax for thymidine increased while the Km wa...

We utilized a reverse transcription-PCR method to examine the effect of estrogen on the expression of mRNA for Bcl-2 and Bax, two modulatory proteins in the apoptotic pathway, in human breast cancer cell line MCF-7. We found that the bcl-2 mRNA levels in the cells exposed to 17 beta-estradiol were higher than those of control cells. Although the relative bax mRNA levels remained unchanged, the ...

Endometriosis represents one of the most frequent causes of restricted fecundity. Despite the progress in medicine, appropriate diagnosis and treatment pose significant problems. The aim of this study was to evaluate ALA-induced PpIX fluorescence of normal endometrial epithelial cells for the diagnosis of endometriosis. PpIX-fluorescence was measured after stimulation with estradiol-17 beta (E2...

We have tested the participation of endogenous opiate pathways in the negative feedback actions of gonadal steroids on pulsatile properties of luteinizing (LH) hormone release in normal men. To this end, sex steroid hormones were infused intravenously at dosages that under steady state conditions selectively suppressed either the frequency or the amplitude of the pulsatile LH signal. The proper...

The study investigates the effect of administered estrogen on plasma creatine kinase (CK) and lactate dehydrogenase (LD) levels in female ovariectomized rats after downhill running. Rats ovariectomized before sexual maturity were subcutaneously implanted with pellets containing 17 beta-estradiol or placebo. Three weeks later they were subjected to a 90-min intermittent downhill running protocol...