1,720,988 research outputs found
Human spermatogenesis in vitro: Respective effects of follicle- stimulating hormone and testosterone on meiosis, spermiogenesis, and sertoli cell apoptosis
No full textIn spite of the availability of abundant data about in vitro spermatogenesis in laboratory animals, studies on human in vitro spermatogenesis are scarce. This study employed a relatively simple culture system, involving all cell types of seminiferous tubules, to analyze the effects of FSH and testosterone (T) on different characteristics of human germ and Sertoli cells in culture. By using fluorescence in-situ hybridization, we show that in vitro reduction of germ cell ploidy can be stimulated by FSH but not by T. FSH, but not T, also induced unexpectedly rapid (24-48 h) morphological changes resembling spermiogenesis, although individual changes (spermatid nucleus condensation and protrusion, cell body elongation, and flagellar growth) proceeded in an uncoordinated way and mostly resulted in the development of abnormal forms of elongated spermatids. Though ineffective alone, T potentiated the effects of FSH on meiosis and spermiogenesis. These effects of T were probably caused by the prevention of Sertoli cell apoptosis, an effect that could not be mimicked by FSH. These data show that, in the presence of high concentrations of FSH and T, human spermatogenesis can proceed in vitro with an unusual speed, but the resulting gametes are morphologically abnormal. The potential practical relevance of these findings to assisted reproduction remains to be assessed
Chemotactic responsiveness of human spermatozoa to follicular fluid is enhanced by capacitation but is impaired in dyspermic semen
No full textOur purpose was to study the chemotactic responsiveness of human spermatozoa from normal and pathological semen samples to follicular fluid (FF), as well as the effect exerted by capacitation on sperm chemotaxis
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effect of growth hormone administration on ICSI outcomes in patients with polycystic ovary syndrome and recurrent implantation failure: A retrospective cross-over study
No full textNovel concepts of human chorionic gonadotropin: reproductive system interactions and potential in the management of infertility.
No full textOBJECTIVE: To extensively review the scientific literature on the potential sites of hCG action and the role of this hormone on reproductive processes not necessarily related to the classic hCG functions of supporting early pregnancy. DESIGN: Review of the international scientific literature and the authors' personal research experience in this area. RESULT(S): The LH/hCG receptor has an almost ubiquitous distribution in reproductive organs, thus suggesting that the actions of hCG might be more extensive than previously thought. Independently of FSH, low-dose hCG can support development and maturation of larger ovarian follicles that have acquired granulosa cells LH/hCG receptors, potentially providing effective and safer ovulation induction regimens. Human chorionic gonadotropin seems to be capable of improving uterine receptivity by enhancing endometrial quality and stromal fibroblast function. Furthermore, through its actions on insulin-like growth factor binding protein-1 and vascular endothelial growth factor, hCG might stimulate endometrial angiogenesis and growth and extend the implantation window, thus making pregnancy more likely. CONCLUSION(S): Mounting evidence indicates that hCG could be mediating relevant actions enhancing fertility and the efficacy of therapeutic procedures used in the management of infertility. Greater understanding of the physiologic roles that hCG plays in human reproduction might suggest novel clinical applications for this traditional hormone of pregnancy
Differentiation of spermatogenic cells during in-vitro culture of testicular biopsy samples from patients with obstructive azoospermia: Effect of recombinant follicle stimulating hormone
No full textIn-vitro differentiation of spermatogenic cells is potential approach to the treatment of male sterility due to spermatogenic arrest. This is a pilot study evaluating meiotic, morphogenetic and cytoplasmic maturation of spermatogenic cells from 18 patients with obstructive azoospermia, during in-vitro culture of partly disintegrated testicular biopsy samples in the presence or absence of recombinant follicle stimulating hormone (rFSH). Meiotic progression was detectable only in the presence of rFSH in culture medium. FSH-dependent condensation, peripheral migration and protrusion of spermatid nuclei, together with FSH-independent flagellar growth, were the main events indicating post-meiotic sperm cell differentiation. rFSH also promoted the progression of spermatid cytoplasmic maturation, reflected by acceleration of acrosomal development. These differentiation events appeared to be mediated by humoral activity of Sertoli cells, without the need for a direct Sertoli-sperm cell contact. These findings provide a background for similar studies in patients with non-obstructive azoospermia. If reproducible in the latter group, transmeiotic in-vitro differentiation of primary spermatocytes may be useful in cases of complete maturation arrest, whereas the development of culture-specific forms may help select viable spermatids in cases of complete spermiogenesis failure
Criteria predicting the absence of spermatozoa in the Sertoli cell-only syndrome can be used to improve success rates of sperm retrieval
No full textVirtual sonographic hysteroscopy in assisted reproduction: A retrospective cost-effectiveness analysis
No full textObjective: To analyze the cost-effectiveness of virtual sonographic hysteroscopy (VSH) performed before in vitro fertilization (IVF) (Scenario 1), frozen embryo transfer (Scenario 2), and oocyte donation (Scenario 3) attempts.
Methods: A retrospective analysis of data extracted from patients' files was conducted. Before undergoing the assigned treatment, VSH was offered to all patients. Cost-effectiveness was calculated on the basis of cost per live birth. The total cost was compared with a control group of patients who declined to have hysteroscopy before their treatment.
Results: A total of 292 women were involved. Virtual sonographic hysteroscopy was performed in 192 women. Conventional operative hysteroscopy was subsequently required in 34 of them (17.7%). Subsequent assisted reproduction attempts resulted in live birth in 111 women-34/69 (49.3%), 35/69 (50.7%), and 42/54 (77.8%) in Scenarios 1, 2, and 3, respectively. This compared favorably with 100 women who declined VSH, with live birth achieved in 15/39 (38.5%), 14/37 (37.8%), and 15/24 (62.5%) in Scenarios 1, 2, and 3, respectively. The overall cost-effectiveness of VSH compared favorably with straightforward treatment performed without this test.
Conclusion: The overall cost-effectiveness of treatment attempts carried out after previous VSH compared favorably with straightforward treatment performed without this test
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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