The Experts below are selected from a list of 48861 Experts worldwide ranked by ideXlab platform
Ago Rinken - One of the best experts on this subject based on the ideXlab platform.
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Determination of biological activity of Gonadotropins hCG and FSH by Förster resonance energy transfer based biosensors
Scientific Reports, 2017Co-Authors: Olga Mazina, Anni Allikalt, Juha S. Tapanainen, Andres Salumets, Ago RinkenAbstract:Determination of biological activity of Gonadotropin hormones is essential in reproductive medicine and pharmaceutical manufacturing of the hormonal preparations. The aim of the study was to adopt a G-protein coupled receptor (GPCR)-mediated signal transduction pathway based assay for quantification of biological activity of Gonadotropins. We focussed on studying human chorionic Gonadotropin (hCG) and follicle-stimulating hormone (FSH), as these hormones are widely used in clinical practice. Receptor-specific changes in cellular cyclic adenosine monophosphate (cAMP, second messenger in GPCR signalling) were monitored by a Förster resonance energy transfer (FRET) biosensor protein ^TEpac^VV in living cells upon activation of the relevant Gonadotropin receptor. The BacMam gene delivery system was used for biosensor protein expression in target cells. In the developed assay only biologically active hormones initiated GPCR-mediated cellular signalling. High assay sensitivities were achieved for detection of hCG (limit of detection, LOD: 5 pM) and FSH (LOD: 100 pM). Even the small-scale conformational changes caused by thermal inactivation and reducing the biological activity of the hormones were registered. In conclusion, the proposed assay is suitable for quantification of biological activity of Gonadotropins and is a good alternative to antibody- and animal-testing-based assays used in pharmaceutical industry and clinical research.
Olga Mazina - One of the best experts on this subject based on the ideXlab platform.
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Determination of biological activity of Gonadotropins hCG and FSH by Förster resonance energy transfer based biosensors
Scientific Reports, 2017Co-Authors: Olga Mazina, Anni Allikalt, Juha S. Tapanainen, Andres Salumets, Ago RinkenAbstract:Determination of biological activity of Gonadotropin hormones is essential in reproductive medicine and pharmaceutical manufacturing of the hormonal preparations. The aim of the study was to adopt a G-protein coupled receptor (GPCR)-mediated signal transduction pathway based assay for quantification of biological activity of Gonadotropins. We focussed on studying human chorionic Gonadotropin (hCG) and follicle-stimulating hormone (FSH), as these hormones are widely used in clinical practice. Receptor-specific changes in cellular cyclic adenosine monophosphate (cAMP, second messenger in GPCR signalling) were monitored by a Förster resonance energy transfer (FRET) biosensor protein ^TEpac^VV in living cells upon activation of the relevant Gonadotropin receptor. The BacMam gene delivery system was used for biosensor protein expression in target cells. In the developed assay only biologically active hormones initiated GPCR-mediated cellular signalling. High assay sensitivities were achieved for detection of hCG (limit of detection, LOD: 5 pM) and FSH (LOD: 100 pM). Even the small-scale conformational changes caused by thermal inactivation and reducing the biological activity of the hormones were registered. In conclusion, the proposed assay is suitable for quantification of biological activity of Gonadotropins and is a good alternative to antibody- and animal-testing-based assays used in pharmaceutical industry and clinical research.
Spyros N. Pavlou - One of the best experts on this subject based on the ideXlab platform.
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Gonadotropin releasing hormone antagonist versus agonist administration in women undergoing controlled ovarian hyperstimulation cycle performance and in vitro steroidogenesis of granulosa lutein cells
American Journal of Obstetrics and Gynecology, 1995Co-Authors: Demetrios Minaretzis, Michael M Alper, Selwyn P Oskowitz, Susan M Lobel, Joseph F Mortola, Spyros N. PavlouAbstract:Abstract OBJECTIVES: We sought to determine the effectiveness of a Gonadotropin-releasing hormone antagonist compared with an agonist in suppressing a spontaneous luteinizing hormone surge in women undergoing controled ovarian hyperstimulation for in vitro fertilization and gamete intrafallopian transfer and to examine whether in vivo administration of these analogs effects granulosa-lutein cells steroidogenesis in vitro. STUDY DESIGN: This prospective case-control study included 30 healthy women undergoing ovarian hyperstimulation with human menopausal Gonadotropins. Fifteen women received the Nal-Glu antagonist, 5 mg intramuscularly daily, when the lead follicle was ≥ 15 mm or serum estradiol leve was ≥500 pg/ml. The control group included 15 women who underwent oocyte retrieval on the same day as the study subjects and were given the agonist leuprolide acetate, 250 μg subcutaneously daily, starting on cycle day 1. Granulosa-lutein cells were purified from follicular aspirates from six subjects and six controls and cultured in parallel, evaluating basal progesterone production, progesterone response to follicle-stimulating hormone or luteinizing hormone and aromatase activity. RESULTS: No difference was demonstrated in the total amount of Gonadotropins received by the two groups. Overall, the Gonadotropin-releasing hormone antagonist was given for only 2.5 ± 0.2 (mean + SEM) days before human chorionic Gonadotropin administration. The antagonist group showed significantly lower levels of serum luteinizing hormone than did the agonist group, 1.0 ± 0.2 versus 4.2 ± 0.5 mlU/ml ( p = 0.0001) on the day of human chorionic Gonadotropin administration. Serum estradiol levels were significantly lower in the antagonist than the agonist group, 820 ± 120 versus 1361 ± 110 pg/ml ( p = 0.003) on the day of human chorionic Gonadotropin administration. There was no difference in the number of retrieved oocytes, but the antagonist group had a higher proportion of mature oocytes, 82% ± 4% versus 62.4% ( p = 0.02), and a higher proportion of embryos of good quality, 69.8% ± 9.8% versus 44.3% ± 7.2% ( p = 0.03) in the agonist group. Granulosa-lutein cells from antagonist-treated women showed significantly lower aromatase activity the first 6 hours after retrieval, 17.6 ± 1.6 versus 31.3 ± 7.4 ng/ml per 6 hours estradiol ( p = 0.03), whereas basal and Gonadotropin-stimulated with progesterone responses were similar. CONCLUSION: Gonadotropin-releasing hormone antagonist administration during the late follicular phase resulted in lower serum luteinizing hormone and estradiol levels and more mature oocytes and embryos of better quality compared with Gonadotropin-releasing hormone agonist administration. These results suggest that Gonadotropin-releasing hormone antagonist administration in ovarian. hyperstimulation has practical advantages over the agonist regimen. Gonadotropin-releasing hormone analogs may have direct action on ovarian function with differential effects on granulosa-lutein cell aromatase activity. This could explain the lower serum estradiol levels routinely observed in women given Gonadotropin-releasing hormone antagonist.
Jiann Loung Hwang - One of the best experts on this subject based on the ideXlab platform.
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effectiveness of cetrorelix for the prevention of premature luteinizing hormone surge during controlled ovarian stimulation using letrozole and Gonadotropins a randomized trial
Fertility and Sterility, 2008Co-Authors: Kok Min Seow, Chii Ruey Tzeng, Jiann Loung Hwang, Yushih YangAbstract:Objective To evaluate the effectiveness of a GnRH antagonist in preventing premature LH surge under a letrozole and Gonadotropin protocol. Design Prospective, randomized clinical trial. Setting A teaching hospital and tertiary medical center. Patient(s) Sixty-one patients were randomly assigned into two letrozole and Gonadotropin–treated groups. These were distinguished by the absence (group I) or presence (group II) of supplementation with 0.25 mg of cetrorelix. Intervention(s) Controlled ovarian stimulation with letrozole and Gonadotropins, cetrorelix and intrauterine insemination. Main Outcome Measure(s) Rate of premature LH surge. Result(s) Compared with group I, the rate of premature LH surge was statistically significantly lower for group II (43.4% [13/30] vs. 19.4% [6/31]), but the amount of Gonadotropins used was statistically significantly higher (817.5 ± 28.5 vs. 907.5 ± 27.3 IU). Patients with premature LH surge had a statistically significantly lower pregnancy rate (21.4% [9/42] vs. 0 [0/18]) relative to their unaffected counterparts. Conclusion(s) A flexible protocol of 0.25 mg of cetrorelix for IUI cycles appears to suppress the rate of premature LH surge during ovarian stimulation with letrozole and Gonadotropins. However, the incidence of premature LH surge remains too high, and modification will be necessary before the application of cetrorelix to IVF treatment.
Vaclav Insler - One of the best experts on this subject based on the ideXlab platform.
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spontaneous ovarian hyperstimulation syndrome concomitant with spontaneous pregnancy in a woman with polycystic ovary disease
American Journal of Obstetrics and Gynecology, 1992Co-Authors: Y Zalel, Z Katz, B Caspi, Herzel Benhur, Rami Dgani, Vaclav InslerAbstract:Ovarian hyperstimulation syndrome has been described after treatment with exogenous Gonadotropins, clomiphene citrate, and Gonadotropin-releasing hormone. Spontaneous ovarian hyperstimulation syndrome has not been described before, except in association with hypothyroidism. We report on a case associated with spontaneous pregnancy, occurring in a woman with polycystic ovary disease.