Kinetic mode switch of rat brain IIA Na channels in Xenopus oocytes excised macropatches

Na currents recorded from inside-out macropatches excised from Xenopus oocytes expressing the subunit of the rat brain Na channel IIA show at least two distinguishable components in their inactivation time course, with time constants differing about tenfold ( _h1 = approx. 150 s and _h2 = approx. 2 ms). In excised patches, the inactivation properties of Na currents changed with time, favoring the faster inactivation kinetics. Analysis of the fast and slow current kinetics shows that only the relative magnitudes of _h1 and _h2 components are altered without significant changes in the time constants of activation or inactivation. In addition, voltage dependence of both activation and steady-state inactivation of Na currents are shifted to more negative potentials in patches with predominantly fast inactivation, although reversal potentials and valences remained unaltered. We conclude that the two inactivation modes discerned in this study are conferred by two states of Na channel the interconversion of which are regulated by an as yet unknown mechanism that seems to involve cytosolic factors.     

女性年龄与卵细胞染色体非整倍体异常的相关关系

目的 :直接从卵细胞水平研究女性年龄与其卵细胞染色体非整倍体间的相关关系。方法 :取试管婴儿助孕技术后未能受精成功的卵细胞 ,采用多色荧光原位杂交方法检测卵细胞 13,16 ,18,2 1和 2 2号染色体的情况。结果 :卵细胞的非整倍体率为 2 7.1% ,随着女性年龄的增加 ,卵细胞的非整倍体率也随之上升 ,两者呈较强的正相关关系 ( r=0 .88,P<0 .0 0 1)。结论 :女性年龄与其染色体非整倍体异常间存在相关性 ,对于 35岁以上行试管婴儿助孕术的妇女应同时进行遗传咨询     

条件基因敲除技术在卵泡发育调控机制研究中的应用进展

卵泡发育是受内分泌、旁分泌及基因调节的复杂生理过程。条件基因敲除能选择去除调控特定发育阶段特定细胞或器官的基因,是在体基因功能研究的主要手段。近年来该技术被广泛应用于卵泡发育调控机制的研究。本文综述了条件基因敲除技术在始基卵泡激活、卵母细胞成熟、排卵、黄体形成及早期胚胎发育等机制研究中的应用进展。     

In vitro maturation

In vitro maturation (IVM) is an in vitro fertilisation (IVF) technique modified to collect immature oocytes from antral follicles, with the final stages of meiosis completed during in vitro culture. The primary benefit of IVM is that it reduces gonadotrophin stimulation in the patient, thereby eliminating the risk of ovarian hyperstimulation syndrome (OHSS) in high-risk patients such as those with polycystic ovaries (PCO) and polycystic ovary syndrome (PCOS). IVM has additional benefits for fertility preservation, particularly in oncofertility patients. IVM research has progressed in recent years to significantly improve success rates and to provide evidence of safety in terms of neonatal and childhood outcomes. More recently, pre-maturation protocols and the discovery of new culture media additives have demonstrated potential to maximise maturation and oocyte developmental competence. In this chapter, we discuss current methodologies used in clinics routinely performing IVM, target patient populations and areas of future research that may improve IVM success.     

Good oocytes for successful IVF cycles

Human fertility is mainly related to the egg quality both in spontaneous and IVF induced cycles.     

Seasonal changes in plasma steroid levels in Indian major carp Labeo rohita: influence of homologous pituitary extract on steroid production and development of oocyte maturational competence

Circannual variations in plasma levels of testosterone (T), 17beta-estradiol (E(2)), and 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (DHP) as well as seasonal fluctuations in ovarian steroid synthetic potential were observed in Indian major carp, Labeo rohita. A study was also conducted to examine the mechanism of the development of gonadotropin-induced maturational competence in oocytes of this fish. The present study recorded the lowest values of plasma E(2) and T in L. rohita during the period from October to January. A mild increase in the levels of these steroids observed in February was followed by their rapid rise reaching peak values in April, when the ovary contained mostly the vitellogenic follicles. In the month of May, as the postvitellogenic follicles predominated in the ovary, there was a decline in plasma concentrations of both T and E(2). Low levels of these steroids in plasma remained until January, except a small elevation detectable during June and July (spawning stage). DHP was not detected in the plasma of this fish collected during the period from August to March. Existence of DHP was first recorded in blood in the month of April (vitellogenic stage) and it quickly reached the peak value in May (postvitellogenic stage), followed by a sudden decline in the month of June. Under stimulation of fish pituitary extract (FPE), as a source of gonadotropin, in vitro production of E(2) and T by the vitellogenic follicles was shown to be highest compared to their production rate in other stages, while the postvitellogenic follicles recorded the highest rate of DHP synthesis. Acquisition of oocyte maturational competence (OMC) was shown to develop either by priming the vitellogenic stage fish with a single dose of FPE or by in vitro addition of FPE in culture. In vitro treatment of trilostane, an inhibitor of 3beta-HSD, blocked the FPE-stimulated steroid production but not the development of OMC. Presence of cycloheximide and actinomycin D in the incubation was shown to inhibit FPE-induced development of OMC, indicating the requirement of de novo protein synthesis for this process.     

Growth hormone replacement improved oocyte quality in a patient with hypopituitarism: A study of follicular fluid

BackgroundGrowth hormone (GH) is known to be involved in ovarian folliculogenesis and oocyte maturation. In patients with poor ovarian response without growth hormone deficiency (GHD), adjuvant GH treatment improves in-vitro fertilization (IVF) results. Improvement of oocyte quality in IVF by GH replacement was reported in only a few patients with GHD. We report on a new case with study of follicular fluid.MethodsA 29-year-old patient with hypopituitarism was referred to our infertility center. She was undergoing hormonal replacement for hypogonadotropic hypogonadism and diabetes insipidus, and did not consider at first GH replacement. Four IVF procedures were performed between 2011 and 2014. Growth hormone replacement (somatotropin 1.1 mg/day) was initiated before the fourth IVF procedure and unmasked central hypothyroidism; levothyroxine (75 mg/day) was introduced. It took 10 months to reach the treatment objectives for insulin-like growth factor 1 (IGF1), free triiodothyronine (fT3) and free thyroxine (fT4). GH, IGF1 and thyroid hormones were measured in the blood and follicular fluid before and after GH and thyroid hormone replacement. Oocyte and embryo quality were also compared.ResultsThe first 3 IVF procedures were performed without GH replacement. 62% to 100% of mature oocytes presented one or more morphologic abnormalities: diffuse cytoplasmic granularity, large perivitelline space with fragments, fragmentation of the first polar body, ovoid shape, or difficult denudation. Embryo quality was moderate to poor (grade B to D), and no pregnancy was obtained after embryo transfer. After GH replacement, hormones levels increased in follicular fluid: GH [7.68 vs. 1.39 mIU/L], IGF1 [109 vs. < 25 ng/mL], fT3 [3.7 vs. 2.5 pmol/L] and fT4 [1.45 vs. 0.84 ng/mL]. Concomitantly, there was dramatic improvement in oocyte quality (no abnormal morphologies) and embryo quality (grade A), allowing an embryo transfer with successful pregnancy.ConclusionsThis is the first report illustrating changes in hormonal levels in follicular fluid and the beneficial effect of GH replacement on oocyte and embryo quality during an IVF procedure in a patient with hypopituitarism. These results suggest that GH replacement is beneficial for oocyte quality in patients with GHD.     

Hair mercury concentrations and in vitro fertilization (IVF) outcomes among women from a fertility clinic

Total hair mercury (Hg) was measured among 205 women undergoing in vitro fertilization (IVF) treatment and the association with prospectively collected IVF outcomes (229 IVF cycles) was evaluated. Hair Hg levels (median = 0.62 ppm, range: 0.03–5.66 ppm) correlated with fish intake (r = 0.59), and exceeded the recommended EPA reference of 1 ppm in 33% of women. Generalized linear mixed models with random intercepts accounting for within-woman correlations across treatment cycles were used to evaluate the association of hair Hg with IVF outcomes adjusted for age, body mass index, race, smoking status, infertility diagnosis, and protocol type. Hair Hg levels were not related to ovarian stimulation outcomes (peak estradiol levels, total and mature oocyte yields) or to fertilization rate, embryo quality, clinical pregnancy rate or live birth rate.     

Antinuclear Antibodies Predicts a Poor IVF-ET Outcome: Impaired Egg and Embryo Development and Reduced Pregnancy Rate

To investigate the impact of anti-nuclear antibodies (ANAs) on the outcome of in vitro fertilization-embryo transfer (IVF-ET), 66 (96 cycles) infertile women positive for anti-nuclear antibodies (ANA+ group), and 233(285 cycles) infertile women negative for ANAs (ANA? group) were enrolled. The clinical characteristics and IVF outcome were compared between the two groups. In the ANA+ group, the proportion of MII oocytes and two-pronuclear zygotes (2PN), cleavage rate, number of available embryos and proportion of available embryos, number of high-quality embryos and proportion of high-quality embryos were significantly lower than those in the ANA? group. In addition, the pregnancy rate and implantation rate in patients positive for ANA was markedly lower than the ANA? patients (28.1% vs 46.4%, 15% vs 25.7%, respectively). Thus, our findings suggest that the presence of ANAs significantly interfere with the oocyte and embryo development, as well as reduce implantation and pregnancy rate in patients undergoing IVF treatment.