When is it safe to switch from oral contraceptives to hormonal replacement therapy?

Women may continue to use oral contraceptives (OCs) into their 40's and 50's, but to date no method has been evaluated to ascertain their ovarian status, i.e., whether fertility and estrogen production have diminished sufficiently so they could be safely switched to hormonal replacement therapy. A group of 12 postmenopausal women who had been, for long periods of time, on a regimen of 3 back-to-back packages (i.e., 63 days on, 7 days off) of low-dose oral contraceptives have been studied. Secondly, a group of 9 perimenopausal women aged 36 to 47 were examined in the same manner. The third group consisted of early reproductive age women (arbitrarily divided into subsets aged 17-25 and 26-35 using low-dose OCs in the customary regimen) as normal controls. Blood samples were obtained on the last day of a pill cycle and at 7 days off the pill. In some menopausal women, blood samples were obtained at both 7 and 14 days off OCs. Serum was assayed by RIA for estradiol, FSH and LH. As expected in the young reproductive age women, estradiol levels increase at one week off the pill, together with a rebound in FSH and LH to follicular phase levels. In the perimenopausal group, there was a sharp distinction based on age. The women over 40 showed a more marked rise in FSH while those aged 36-40 showed a distinctly lesser response. Estradiol levels were variable, but tended to show some age grouping. Little diagnostic separation was observed for LH. In postmenopausal women, FSH levels were not always elevated at one week post-pill, and even in a second trial with sampling at one and two weeks off the OC, not all postmenopausal women showed a "menopausal" increase in FSH. The more uniform feature was that estradiol levels never increased above basal values. The study found that serum estradiol levels increase after a week off the pill in controls, but are unchanged at one and two weeks in the menopausal group. FSH levels rebound normally in reproductive age women and usually, but not always, increase substantially in postmenopausal women. After two weeks off OCs, an increased FSH and/or no change in basal estradiol levels is strong evidence that it is now safe (contraceptively speaking) to switch from OCs to standard hormone replacement regimens.     

On the Growth and Microstructure of Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

Carbon nanotubes (CNTs) were deposited on various substrates namely untreated silicon and quartz, Fe-deposited silicon and quartz, HF-treated silicon, silicon nitride-deposited silicon, copper foil, and stainless steel mesh using thermal chemical vapor deposition technique. The optimum parameters for the growth and the microstructure of the synthesized CNTs on these substrates are described. The results show that the growth of CNTs is strongly influenced by the substrate used. Vertically aligned multi-walled CNTs were found on quartz, Fe-deposited silicon and quartz, untreated silicon, and on silicon nitride-deposited silicon substrates. On the other hand, spaghetti-type growth was observed on stainless steel mesh, and no CNT growth was observed on HF-treated silicon and copper. Silicon nitride-deposited silicon substrate proved to be a promising substrate for long vertically aligned CNTs of length 110–130 μm. We present a possible growth mechanism for vertically aligned and spaghetti-type growth of CNTs based on these results.     

Concerted evolution in an egg receptor for a rapidly evolving abalone sperm protein

Gamete interactions during fertilization exhibit species specificity. In abalone, the sperm protein lysin species-specifically creates a hole in the egg envelope. Lysin evolves rapidly by positive Darwinian selection. Evolution of the egg receptor for lysin provides the selective pressure for lysin's divergence. The egg receptor for lysin is a tandemly repeated sequence that evolves by concerted evolution. Concerted evolution in the egg receptor could explain the rapid, adaptive evolution in sperm lysin and may provide an underlying molecular mechanism that gives rise to species-specific fertilization.     

Physiopathology of premature progesterone elevation

OBJECTIVE: To determine the effects of the last hMG administration on plasma P and androgen profiles during controlled ovarian hyperstimulation (COH) for IVF-ET. DESIGN: Controlled clinical study. SETTING: The IVF-ET program of a tertiary outpatient care center, H?pital A. Béclère, Clamart, France. PATIENTS: Nine IVF-ET candidates aged 25 to 36 years having presented normal responses to COH in previous IVF-ET cycles. INTERVENTIONS: Controlled ovarian hyperstimulation was induced for IVF-ET using hMG after endogenous gonadotropins were suppressed with a time-release GnRH agonist. Just before the last hMG administration (225 IU), the participants were hospitalized for 24 hours for serial blood sampling. These occurred before (baseline) and after hMG administration, every 30 minutes for 1 hour, hourly for 4 hours, and every 3 hours for the remaining part of a 24-hour post-hMG observation period. MAIN OUTCOME MEASURE: Measurement of P, T, androstenedione (A), E2, FSH, and LH. RESULTS: Plasma P and androgens (T and A) increased significantly, reaching peak values 12 to 15 hours after hMG administration and decreased progressively thereafter, to reach values not significantly different from baseline 24 hours after hMG administration. Plasma E2 levels increased progressively and steadily during the 24-hour observation period. Plasma FSH levels remained constant after hMG administration while LH stayed undetectable. CONCLUSION: In COH cycles induced for IVF-ET, the hormonal profile after the last hMG injection suggests that hMG triggers an increase in plasma P and androgens that culminates 12 to 15 hours after hMG administration. This elevation in plasma P and androgens observed after hMG administration is likely to reflect a direct action of the LH and/or FSH components of hMG on granulosa cells. In some women these hormonal consequences of hMG treatment may impair endometrial receptivity in IVF-ET cycles.     

A simple program which processes liquid scintillation counting data from samples containing both 125I and 3H under conditions of varying quench

A human study of the effects of topical nystatin (Mycostatin) therapy of oral candidiasis showed that effects of treatment were limited to the time in which the drug was used. Two weeks of therapy resulted in significant reduction in number of organisms and marked improvement in signs and symptoms of candidiasis. The condition recurred rapidly following cessation of treatment. No change in specific anticandida antibody in saliva or in adherence of Candida albicans to mucosal epithelium (in vitro) was seen with treatment.