162,266 research outputs found
Oocyte maturation and quality: role of cyclic nucleotides
No full textAdvance Publication first posted online on 15 July 2016 - Accepted manuscriptThe cyclic nucleotides, cAMP and cGMP, are the key molecules controlling mammalian oocyte meiosis. Their roles in oocyte biology have been at the forefront of oocyte research for decades and many of the long standing controversies in relation to the regulation of oocyte meiotic maturation are now resolved. It is now clear that the follicle prevents meiotic resumption through the actions of natriuretic peptides and cGMP inhibiting the hydrolysis of intra-oocyte cAMP and that the preovulatory gonadotrophin surge reverses these processes. The gonadotrophin surge also leads to a transient spike in cAMP in the somatic compartment of the follicle; research over the past 2 decades has conclusively demonstrated that this surge in cAMP is important for the subsequent developmental capacity of the oocyte. This is important, as oocyte in vitro maturation (IVM) systems practiced clinically do not recapitulate this cAMP surge in vitro, possibly accounting for the lower efficiency of IVM compared to clinical IVF. This review focuses in particular on this latter aspect - the role of cAMP/cGMP in the regulation of oocyte quality. We conclude that clinical practice of IVM should reflect this new understanding of the role of cyclic nucleotides, thereby creating a new generation of ART and fertility treatment options.Gilchrist RB, Luciano AM, Richani D, Zeng HT, Wang X, De Vos M, Sugimura S, Smitz J, Richard FJ and Thompson J
Reevaluation and evolution of the simulated physiological oocyte maturation system
No full textLetter to the Editor. Available online 2 April 2015Abstract not availableR.B. Gilchrist, H.T. Zeng, X. Wang, D. Richani, J. Smitz, J.G. Thompso
Promotion of EGF receptor signaling improves the quality of low developmental competence oocytes
No full textAvailable online 14 May 2015Abstract not availableSatoshi Sugimura, Lesley J. Ritter, Ryan D. Rose, Jeremy G. Thompson, Johan Smitz, David G. Mottershead, Robert B. Gilchris
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Rapport VIb.4. Modèle mathématique de la qualité de l’eau dans un estuaire partiellement stratifié
No full textIs presented herein the general model of the water quality, that puts forward the connections between the oxy do-reduction balance, bacterial activity and hydrodynamical processes. Systematical application of this model to the Escaut River estuary. Model general principle, mathematical solution taking into account the assumption about the internal thermodynamical equilibrium, off-equilibrium evolution, experimental results and bibliography.
It may be noted that the phenomena taken into account appear also in the other river waters and, generally speaking, in the natural systems where is an intensive heterotrophical activity as the layer near the bottom of stratified reservoirs or the pore water of sediments.Présentation d’un modèle général de la qualité de l’eau mettant en évidence les relations entre le bilan d’oxydo-réduction, l’activité bactérienne et les processus hydrodynamiques. Application systématique du dit modèle à l’estuaire de l’Escaut ; principe général du modèle ; résolution mathématique compte tenu de l’hypothèse d’équilibre thermodynamique interne ; évolution hors-équilibre ; résultats expérimentaux ; bibliographie.
A noter que les phénomènes pris en compte apparaissent dans d’autres rivières et en général dans les systèmes naturels sièges d’une activité hétérotrophe intense comme la couche de fond des réservoirs stratifiés ou l’eau interstitielle de sédiments.Billen Gilles, Smitz J. Rapport VIb.4. Modèle mathématique de la qualité de l’eau dans un estuaire partiellement stratifié. In: La mécanique des fluides et l'environnement. Prévision et maîtrise de la qualité de l'eau et de l'air. Compte rendu des quatorzièmes journées de l'hydraulique. Paris, 7-9 septembre 1976. Tome 2, 1977
Melatonin has dose-dependent effects on folliculogenesis, oocyte maturation capacity and steroidogenesis
No full textChemo and/or radiotherapy applied to young cancer patients most often have severe effects upon female fertility. Today, few options are available to protect ovarian function in females. However, these options are either ineffective, belong to the field of experimental research or/and are not applicable to all patients. Drugs that could protect the oocyte and its surrounding feeder cells from damage can be of great importance. Melatonin, being an important indirect antioxidant and a powerful direct free radical scavenger could be such a reagent. This paper reports the direct effects of different melatonin concentrations (range: 1 nM to 2 mM) on folliculogenesis and oogenesis of in vitro cultured mouse ovarian follicles. Early secondary mouse follicles were cultured in vitro for 12 days under different melatonin regimes. Every fourth day, survival rates were scored, follicles were morphologically evaluated and medium was collected for steroid analyses. On day 12, in vitro ovulation was induced by hCG/EGF. Eighteen hours later, oocytes were measured, oocyte maturation was evaluated and normality of spindle and chromosomes ascertained. Results obtained in this study indicated that 2 mM melatonin is toxic. One mM negatively influenced oocyte maturation capacity. In the presence of 100 mu M melatonin, androstenedione and progesterone were increased whereas estradiol was not influenced. Lower melatonin concentrations had no effect on the evaluated parameters. These data indicate an effect of melatonin on theca cell steroidogenesis. For prophylactic use, a dose of 10 mu M could be suitable to reduce oxidative stress in cultured follicles. (c) 2006 Elsevier Ireland Ltd. All rights reserved
Melatonin has dose-dependent effects on folliculogenesis, oocyte maturation capacity and steroidogenesis
No full textChemo and/or radiotherapy applied to young cancer patients most often have severe effects upon female fertility. Today, few options are available to protect ovarian function in females. However, these options are either ineffective, belong to the field of experimental research or/and are not applicable to all patients. Drugs that could protect the oocyte and its surrounding feeder cells from damage can be of great importance. Melatonin, being an important indirect antioxidant and a powerful direct free radical scavenger could be such a reagent. This paper reports the direct effects of different melatonin concentrations (range: 1 nM to 2 mM) on folliculogenesis and oogenesis of in vitro cultured mouse ovarian follicles. Early secondary mouse follicles were cultured in vitro for 12 days under different melatonin regimes. Every fourth day, survival rates were scored, follicles were morphologically evaluated and medium was collected for steroid analyses. On day 12, in vitro ovulation was induced by hCG/EGF. Eighteen hours later, oocytes were measured, oocyte maturation was evaluated and normality of spindle and chromosomes ascertained. Results obtained in this study indicated that 2 mM melatonin is toxic. One mM negatively influenced oocyte maturation capacity. In the presence of 100 mu M melatonin, androstenedione and progesterone were increased whereas estradiol was not influenced. Lower melatonin concentrations had no effect on the evaluated parameters. These data indicate an effect of melatonin on theca cell steroidogenesis. For prophylactic use, a dose of 10 mu M could be suitable to reduce oxidative stress in cultured follicles. (c) 2006 Elsevier Ireland Ltd. All rights reserved
Multi-center evaluation of assays for sex hormone binding globulin, testosterone, and estradiol on the ABBOTT ARCHITECT SYSTEM
No full textEvaluation of the analytical performance parameters for Abbott Architect SHBG and DHEAS assays.
No full text- …
