334 research outputs found

    Recombinant human follicle-stimulating hormone produces more oocytes with a lower total dose per cycle in assisted reproductive technologies compared with highly purified human menopausal gonadotrophin: a meta-analysis

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    <p>Abstract</p> <p>Background</p> <p>Human menopausal gonadotrophins and recombinant human follicle stimulating hormone are the two main gonadotrophin products utilized for controlled ovarian stimulation in assisted reproductive technologies. In this meta-analysis, the number of oocytes was designated as the most relevant endpoint directly resulting from ovarian stimulation, and therefore where the drug effect may be estimated with the best sensitivity.</p> <p>Methods</p> <p>All published randomized controlled trials on ovarian stimulation comparing the two gonadotrophin products were evaluated. Internal validity was determined using Chalmers' validated scale. If trials did not meet the established quality criteria, a sensitivity analysis assessed the stability of the results. The comparison of continuous variables was conducted following the weighted mean difference and the standardized mean difference (Cohen's effect size) with the random model. Given the known relationship of baseline conditions on treatment endpoints, results were adjusted for age, body mass index and type of infertility.</p> <p>Results</p> <p>Sixteen studies involving 4040 patients were included. Treatment with human menopausal gonadotrophins resulted in fewer oocytes (-1.54; 95% CI: -2.53 to -0.56; P < 0.0001) compared to recombinant human follicle-stimulating hormone. When adjusting for baseline conditions, the mean difference estimate was -2.10 (95% CI: -2.83 to -1.36; P < 0.001). A higher total dose of human menopausal gonadotrophin was necessary (mean difference, 235.46 IU [95% CI: 16.62 to 454.30; P = 0.03]; standardized mean difference, 0.33 [95% CI: 0.08 to 0.58; P = 0.01]). The pregnancy absolute risk difference (RD [hMG-r-hFSH]) for fresh transfers was 3% (P = 0.051), and the relative risk 1.10 (P = 0.06). When adjusted for baseline conditions, the relative risk was 1.04 (P = 0.49) and absolute difference was 0.01 (P = 0.34), respectively.</p> <p>Conclusions</p> <p>Because baseline conditions are predictive of outcome, meta-analytic results are more sensitive when these variables are considered. Using an endpoint closely associated with the stimulation period, sufficient sensitivity is achieved to compare gonadotrophin treatments. As the largest meta-analysis published to date on this subject, treatment with human menopausal gonadotrophins is characterized by fewer oocytes and a higher total dose. When considering only fresh transfers, pregnancy rates were similar.</p

    The impact of significant input of fine sediment on benthic fauna at tributary junctions: a case study of the Bermejo-Paraguay River confluence, Argentina

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    This study examines the morphological features, suspended sediment inputs and hydraulic conditions within a large river in association with ecological patterns before and after a tributary confluence. In order to examine these effects, the macroinvertebrate distributions from three reaches of the Paraguay and Bermejo Rivers (Paraguay-Argentina) are investigated. The Bermejo River is a tributary that supplies significant quantities of fine sediment to the Paraguay River, primarily in suspension. Two reaches were examined on the Paraguay River, upstream and downstream of the Bermejo River junction, with the third study reach located on the Bermejo River, upstream of the confluence with the Paraguay River. The results provide clear evidence that a significantly increased loading of fine sediment at a river confluence has effects on the distribution and potential movement of benthic invertebrates in the lotic environment by representing physical barriers at affected sites. These effects may be important at both local and regional scales, and such increases in suspended sediment (especially associated with anthropogenic change) may thus pose a major threat to ecosystem integrity that has been historically underestimated

    Invasion process of Limnoperna fortunei (Bivalvia: Mytilidae): the case of Uruguay river and emissaries of the Esteros del Iberá Wetland, Argentina

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    Limnoperna fortunei (Dunker, 1857), during its invasion process in South America, has caused severe impacts both on natural environments altering native biodiversity, ecosystem structure and function-, and on man-made structures causing economic looses. Twenty-one samples were taken from the right bank of the Uruguay River, from tributaries of the Uruguay and Paraná Rivers, the drainage of the Esteros del Ibera Wetland. Based on this fieldwork, the presence of larvae and adults of L. fortunei was determined. Also, through the comparison of environmental characteristic with the known tolerance limits for the species, the possibility of its establishment in environments not yet invaded was determined. Most of the sampling stations have features that allow the development of stable populations L. fortunei, including the rivers that drain the Esteros del Ibera, allowing access of this invasive species to this important wetland.Facultad de Ciencias Naturales y Muse

    Invasion process of Limnoperna fortunei (Bivalvia: Mytilidae): the case of Uruguay river and emissaries of the Esteros del Iberá Wetland, Argentina

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    Limnoperna fortunei (Dunker, 1857), during its invasion process in South America, has caused severe impacts both on natural environments altering native biodiversity, ecosystem structure and function-, and on man-made structures causing economic looses. Twenty-one samples were taken from the right bank of the Uruguay River, from tributaries of the Uruguay and Paraná Rivers, the drainage of the Esteros del Ibera Wetland. Based on this fieldwork, the presence of larvae and adults of L. fortunei was determined. Also, through the comparison of environmental characteristic with the known tolerance limits for the species, the possibility of its establishment in environments not yet invaded was determined. Most of the sampling stations have features that allow the development of stable populations L. fortunei, including the rivers that drain the Esteros del Ibera, allowing access of this invasive species to this important wetland.Facultad de Ciencias Naturales y Muse

    Reproductive Suicide: Similar Mechanisms of Aging in C. elegans and Pacific Salmon

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    In some species of salmon, reproductive maturity triggers the development of massive pathology resulting from reproductive effort, leading to rapid post-reproductive death. Such reproductive death, which occurs in many semelparous organisms (with a single bout of reproduction), can be prevented by blocking reproductive maturation, and this can increase lifespan dramatically. Reproductive death is often viewed as distinct from senescence in iteroparous organisms (with multiple bouts of reproduction) such as humans. Here we review the evidence that reproductive death occurs in C. elegans and discuss what this means for its use as a model organism to study aging. Inhibiting insulin/IGF-1 signaling and germline removal suppresses reproductive death and greatly extends lifespan in C. elegans, but can also extend lifespan to a small extent in iteroparous organisms. We argue that mechanisms of senescence operative in reproductive death exist in a less catastrophic form in iteroparous organisms, particularly those that involve costly resource reallocation, and exhibit endocrine-regulated plasticity. Thus, mechanisms of senescence in semelparous organisms (including plants) and iteroparous ones form an etiological continuum. Therefore understanding mechanisms of reproductive death in C. elegans can teach us about some mechanisms of senescence that are operative in iteroparous organisms

    The stem-archosaur evolutionary radiation in South America

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    The oldest archosauromorphs (dinosaurs, birds, crocodiles, and their stem-taxa) arerecorded in middle−upper Permian rocks, but it was not after the Permo−Triassic massextinction that the group shows a substantially high taxonomic richness andecomorphological disparity. The early evolutionary history of the Archosauromorphaduring the Early and Middle Triassic is mainly based on fossils recovered from rocks insouthern Africa, Europe and Asia, whereas South America possesses a morecomplete fossil record of the group only in the Late Triassic. Here we revisit, discuss,and reanalyse the non-archosaurian archosauromorph fossil record of the current-daySouth America. The Early Triassic archosauromorph record in this continent is stillscarce, but it documents the early evolution of the group in western Pangaea and iscrucial to understand more globally the biotic recovery after the Permo−Triassic massextinction. The Middle Triassic record is extremely scarce, but the Late Triassicarchosauromorph assemblage of South America is among the most diverse andabundant worldwide. The last decade has witnessed a considerable improvement inour knowledge of the record, taxonomy, phylogeny, and macroevolution of the groupwith the input from the South American fossils. Nevertheless, a considerable amount ofresearch is needed and ideally should be focused on some particular aspects of theTriassic evolutionary radiation of Archosauromorpha. Among them, the Early Triassicrecord should be expanded, more numerous and more complete Middle Triassicarchosauromorph specimens are crucial to have a more complete picture of theevolution of the group, and the taxonomy of groups like proterochampsids andhyperodapedontine rhynchosaurs should be clarified through detailed anatomical work.Fil: Ezcurra, Martin Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’; ArgentinaFil: Montefeltro, Felipe C.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Pinheiro, Felipe L.. Universidade Federal do Pampa; BrasilFil: Trotteyn, Maria Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Gentil, Adriel Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’; ArgentinaFil: Lehmann, Oscar Emilio Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’; ArgentinaFil: Pradelli, Luciano Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’; Argentin

    Production of YP170 vitellogenins promotes intestinal senescence in C. elegans

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    During aging, etiologies of senescence cause multiple pathologies, leading to morbidity and death. To understand aging requires identification of these etiologies. For example, C. elegans hermaphrodites consume their own intestinal biomass to support yolk production, which in later life drives intestinal atrophy and ectopic yolk deposition. Yolk proteins (vitellogenins) exist as 3 abundant species: YP170, derived from vit-1 - vit-5, and YP115 and YP88, derived from vit-6. Here we show that inhibiting YP170 synthesis leads to a reciprocal increase in YP115/YP88 levels and vice versa, an effect involving post-transcriptional mechanisms. Inhibiting YP170 production alone, despite increasing YP115/YP88 synthesis, reduces intestinal atrophy as much as inhibition of all YP synthesis, which increases lifespan. By contrast, inhibiting YP115/YP88 production alone accelerates intestinal atrophy and reduces lifespan, an effect that is dependent upon increased YP170 production. Thus, despite copious abundance of both YP170 and YP115/YP88, only YP170 production is coupled to intestinal atrophy and shortened lifespan. In addition, increasing levels of YP115/YP88 but not of YP170 increases resistance to oxidative stress; thus, longevity resulting from reduced vitellogenin synthesis is not attributable to oxidative stress resistance
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