903 resultados para Gonadal contention
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The observation that mice with a selective ablation of the androgen receptor (AR) in Sertoli cells (SC) (SCARKO mice) display a complete block in meiosis supports the contention that SC play a pivotal role in the control of germ cell development by androgens. To delineate the physiological and molecular mechanism responsible for this control, we compared tubular development in pubertal SCARKO mice and littermate controls. Particular attention was paid to differences in SC maturation, SC barrier formation and cytoskeletal organization and to the molecular mediators potentially involved. Functional analysis of SC barrier development by hypertonic perfusion and lanthanum permeation techniques and immunohistochemical analysis of junction formation showed that SCARKO mice still attempt to produce a barrier separating basal and adluminal compartment but that barrier formation is delayed and defective. Defective barrier formation was accompanied by disturbances in SC nuclear maturation (immature shape, absence of prominent, tripartite nucleoli) and SC polarization (aberrant positioning of SC nuclei and cytoskeletal elements such as vimentin). Quantitative RT-PCR was used to study the transcript levels of genes potentially related to the described phenomena between day 8 and 35. Differences in the expression of SC genes known to play a role in junction formation could be shown from day 8 for Cldn11, from day 15 for Cldn3 and Espn, from day 20 for Cdh2 and Jam3 and from day 35 for ZO-1. Marked differences were also noted in the transcript levels of several genes that are also related to cell adhesion and cytoskeletal dynamics but that have not yet been studied in SC (Actn3, Ank3, Anxa9, Scin, Emb, Mpzl2). It is concluded that absence of a functional AR in SC impedes the remodeling of testicular tubules expected at the onset of spermatogenesis and interferes with the creation of the specific environment needed for germ cell development.
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To investigate the reproductive biology of Callinectes ornatus gonadal and moulting cycles were studied over two consecutive years in the Ubatuba region. Six stages of gonadal development were detected in females and four in males. Observations on the number of ovigerous females, on the moulting stages of males and females, and on the percentage of individuals exhibiting mature gonads reveal a continuous reproductive cycle, the stages of which progress at different rates. These data support the hypothesis that C. ornatus shows staggered spawning, with possibly more than one annual reproductive period. A pause in growth before the terminal moult may occur in this species.
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We investigated plasma luteinizing hormone (LH) concentration in domestic male cats challenged with Luteinizing Hormone Releasing Hormone Analog (LHRH-A) [des Gly10, (DTrp6)-LHRH ethylamide] that mediates the function of the hypothalamic-piruitary-gonadal axis (HPG). Plasma LH concentrations in cats treated daily with LHRH (10 μg/ 100 μl/kg/day, subcutaneously - sc) for 19 days (LHRH group) and in controls treated with saline (NaCl - 0.9%, same volume - SAL group) were chronically studied. LHRH administration (sc) for 15 days induced a significant fall (P < 0.05) in plasma LH concentrations during the chronic study. After the 15th day of treatment the groups were divided once more into animals treated with LHRH (10 μg/100 μl/kg) or saline (iv), and a time course study (300 min) was performed (acute study). Next, four groups of cats were compared in an acute study involving the sc/iv administration of SAL/SAL, SAL/LHRH, LHRH/SAL, and LHRH/LHRH. The responses of the SAL animals challenged by acute iv administration of LHRH (group SAL/LHRH) were significantly higher (P < 0.01) than those of animals treated with LHRH (sc) (group LHRH/LHRH). LH release was also significantly increased in the latter group (P < 0.05), although the effect was short lasting, being recorded only at the first observation (45 min). An in vitro study with the pituitaries was also performed on day 20. Mean (±SEM) LH concentrations in the culture medium containing pituitaries with LHRH (10-7 M) or saline were determined. In vitro analysis of these pituitaries demonstrated a significantly reduced response (P < 0.05) by animals treated sc with LHRH for 19 days. This study represents a source of data for the domestic cat going beyond its own physiology. Serving as a model, this animal provide important information for the study of reproductive physiology in other members of its family (Felidae), almost all of them threatened with extinction.
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Broiler chicks aged 12 h after hatching were allotted according to a block design in a 7 x 2 factorial schedule of 14 treatments and four replications of 50 chicks each one. The main experimental factors were fasting for 0, 6, 12, 18, 24, 30, and 36 h after chick placement and sex. Independent of sex, fasting had a negative linear effect on weight and productivity of broilers at market age (42 d) without affecting feed conversion or mortality index. Groups subjected to 18 and 36 h of fasting after placement, corresponding to 30 and 48 h posthatching fasting, had lower biometrical values for small intestine (length, weight, and size; villus height; and crypt depth) than chicks fed immediately after placement. According to the Pearson test, BW of birds at 21 and 42 d were significantly correlated to BW at 7 d (r = 0.77) and 21 d (r = 0.45), respectively. Males performed better than females but had higher mortality rates. Fasting did not influence serum concentrations of corticosterone or sexual steroid hormones. Nevertheless, early signs of sexual dimorphism arose from the high estradiol (E2) concentration on female serum. Heterophil:lymphocyte ratio was not different among treatments, indicating that early fasting did not seem to be a stress factor 21 or 42 d after fasting. The results suggested a maximum fasting of 24 h after hatching in order to preserve broiler productivity at market age.
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The morphologic events related to the prenatal development of the ovaries in 81 Nelore breed embryos and fetuses gathered in a local slaughterhouse, with age range from 26 to 240 days following fecundation were studied. The age of fetuses was estimated from measures taken in the cranium-caudal direction. The sex was identified from macroscopic observations and using Polymerase Chain Reaction (PCR) technique. For histology the gonads were fixed in Bourn's fluid for 24 hours and 5 μm thick section's were stained with hematoxylin-eosin. Formation of gonadal ridge and presence of germinal cells were found within it at 29 and 34 days, respectively. Oogonia and primordial follicles, unlike the growing follicles, exhibited significant differences in diameter in the various periods studied. Positive correlation (P<0.05) was found between the diameter of oogonia and their nucleus as well as between primordial and growing follicles with their oocytes and respective nuclei. The gonad was fully formed at 40 days. Primordial follicles, in the growing stage, and antral follicles first appeared, approximately at 95, 140, and 180 days, respectively. Despite the onset and duration of oogenesis being similar to that of taurine breeds, folliculogenesis initiates at an early stages in the Nelore breed.
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Objective: This study evaluated the augmentation of venlafaxine with hormone therapy in the treatment of postmenopausal depression. The hormones evaluated were estrogen (0.625 mg) in combination with medroxyprogesterone acetate (2.5 mg) and methyltestosterone (2.5 mg). Design: Seventy-two menopausal women (mean age: 53.6 ± 4.27 years) diagnosed with depression (Montgomery-Åsberg Depression Rating Scale [MADRS] scores ≥ 20) were treated with venlafaxine and one of the following hormone therapy combinations, in a double-blind regimen: estrogen + medroxyprogesterone + methyltestosterone (group 1, n = 20); estrogen + medroxyprogesterone acetate (group 2, n = 20); methyltestosterone only (group 3, n = 16); and no hormone therapy (group 4, n = 16). Study duration was 24 weeks. Primary efficacy outcome was remission according to the MADRS, whereas secondary efficacy measures included the Clinical Global Impression (CGI), Blatt-Kupperman Index, and Women's Health Questionnaire (WHQ). Results: Forty-eight patients completed the study. All groups showed significant improvement from baseline. Group 3 demonstrated significant improvement on the MADRS compared with placebo (group 4) at weeks 20 (P = 0.048) and 24 (P = 0.030); effect size 8.04 (0.83; 15.26) (P = 0.029), but also had the highest dropout rate. Groups 1 and 3 had significant CGI improvement rates compared with placebo: 42.23% (P = 0.012) and 44.45% (P = 0.08), respectively. There were no differences in the WHQ or BKI scores among the groups. Conclusions: Methyltestosterone 2.5 mg had the highest effect size compared with placebo, but the high dropout rate prevented its efficacy from being determined. Estrogen plus medroxyprogesterone, combined with methyltestosterone or otherwise, demonstrated a trend toward increased efficacy of venlafaxine. Further larger-scale clinical trials are needed to elucidate the findings of this pilot study. © 2006 by The North American Menopause Society.
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In this study, the length-weight relationship and the condition factor of Brycon opalinus were analyzed in three rivers within the Santa Virgínia Unit, at Serra do Mar State Park, in São Paulo State. The different conditions in these three environments were evidenced, such as the seasonality, reproductive period, and the differences between females and males according to the parameters which evidenced the best physiological condition of the fish. In this species, the condition factor varied along the seasons at all three collection sites. The length of the first gonadal maturation and the reproductive period were long, with the highest intensity in the spring and summer.
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Hyperprolactinemia is the most frequent endocrine disorder of the hypothalamus-hypophysis axis observed in women of reproductive age. It is characterized by elevated serum prolactin levels. Prolactin production is regulated by the inhibitory action of a neurotransmitter, dopamine. Clinical manifestations include irregular menstrual cycle, amenorrhea, galactorrhea, infertility and libido decrease, but psychological symptoms, especially anxiety and depression, have also been associated with hyperprolactinemia. Nonetheless, few studies about this condition are available. In the pathogenesis of psychiatric disorders, prolactin may have either a direct action on the central nerve system or an indirect effect via gonadal hormones or function as independent factors as a result of dopamine depletion. Thus, since the prevalence of psychiatric disorders in patients with hyperprolactinemia was detected, it was concluded that further studies are necessary to investigate the basis of a potential relationship between both hyperprolactinemic and psychiatric conditions.
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The aim of this study was to accompany the process of testicular development from the non-differentiable phase to its complete formation. Embryos and fetuses of Nelore breed cows (Bos Taurus indicus) were obtained in slaughterhouses near the Uberlandia city, Minas Gerais. The gonads and the embryos were fixed in Bouin's fixative and afterwards processed for conventional optical microscopy. The gonadal was observed firstly in a 1.0 cm long embryo. In 2.5 cm long embryos the presence of the albuginea allows the sex identification. The mean thickness of the albuginea ranged from 29.08 to 558.45 mm. Gradually increase of vascularization of the albuginea and parenchyma is observed. The mediastinum is located centrally. There was a decrease in the space occupied by the testicular cords, from 63.71 to 41.99% of the total testes volume. Its diameter ranged from 31.68 to 48.80 mm. The diameter of germinal cells (and their nuclei) was from 12.27 (6.65) to 16.95 914.21) mm. The quantity of germinal cells by cross section of cord decreased from a maximum of 2.80 to 0.76. The total number of germinal cells was from 16 at the beginning of colonization of the gonad to 18.32 x 106 at the end of the study. The number of Sertoli's cells by cross section of cord ranged from 10.00 to 16.25. The results obtained show that the origin and formation of testes in embryos and fetuses from Nelore breed cows (Bos taurus indicus) does occur in a very similar way to what is described for Bos taurus taurus.
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Background: Fluctuations of estradiol and progesterone levels caused by the menstrual cycle worsen asthma symptoms. Conflicting data are reported in literature regarding pro and anti-inflammatory properties of estradiol and progesterone.Methods: Female Wistar rats were ovalbumin (OVA) sensitized 1 day after resection of the ovaries (OVx). Control group consisted of sensitized-rats with intact ovaries (Sham-OVx). Allergic challenge was performed by aerosol (OVA 1%, 15 min) two weeks later. Twenty four hours after challenge, BAL, bone marrow and total blood cells were counted. Lung tissues were used as explants, for expontaneous cytokine secretion in vitro or for immunostaining of E-selectin.Results: We observed an exacerbated cell recruitment into the lungs of OVx rats, reduced blood leukocytes counting and increased the number of bone marrow cells. Estradiol-treated OVx allergic rats reduced, and those treated with progesterone increased, respectively, the number of cells in the BAL and bone marrow. Lungs of OVx allergic rats significantly increased the E-selectin expression, an effect prevented by estradiol but not by progesterone treatment. Systemically, estradiol treatment increased the number of peripheral blood leukocytes in OVx allergic rats when compared to non treated-OVx allergic rats. Cultured-BAL cells of OVx allergic rats released elevated amounts of LTB4 and nitrites while bone marrow cells increased the release of TNF-α and nitrites. Estradiol treatment of OVx allergic rats was associated with a decreased release of TNF-α, IL-10, LTB4 and nitrites by bone marrow cells incubates. In contrast, estradiol caused an increase in IL-10 and NO release by cultured-BAL cells. Progesterone significantly increased TNF- α by cultured BAL cells and bone marrow cells.Conclusions: Data presented here suggest that upon hormonal oscillations the immune sensitization might trigger an allergic lung inflammation whose phenotype is under control of estradiol. Our data could contribute to the understanding of the protective role of estradiol in some cases of asthma symptoms in fertile ans post-menopausal women clinically observed. © 2010 de Oliveira et al; licensee BioMed Central Ltd.
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Includes bibliography
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Software Transactional Memory (STM) systems have poor performance under high contention scenarios. Since many transactions compete for the same data, most of them are aborted, wasting processor runtime. Contention management policies are typically used to avoid that, but they are passive approaches as they wait for an abort to happen so they can take action. More proactive approaches have emerged, trying to predict when a transaction is likely to abort so its execution can be delayed. Such techniques are limited, as they do not replace the doomed transaction by another or, when they do, they rely on the operating system for that, having little or no control on which transaction should run. In this paper we propose LUTS, a Lightweight User-Level Transaction Scheduler, which is based on an execution context record mechanism. Unlike other techniques, LUTS provides the means for selecting another transaction to run in parallel, thus improving system throughput. Moreover, it avoids most of the issues caused by pseudo parallelism, as it only launches as many system-level threads as the number of available processor cores. We discuss LUTS design and present three conflict-avoidance heuristics built around LUTS scheduling capabilities. Experimental results, conducted with STMBench7 and STAMP benchmark suites, show LUTS efficiency when running high contention applications and how conflict-avoidance heuristics can improve STM performance even more. In fact, our transaction scheduling techniques are capable of improving program performance even in overloaded scenarios. © 2011 Springer-Verlag.
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Transactional memory (TM) is a new synchronization mechanism devised to simplify parallel programming, thereby helping programmers to unleash the power of current multicore processors. Although software implementations of TM (STM) have been extensively analyzed in terms of runtime performance, little attention has been paid to an equally important constraint faced by nearly all computer systems: energy consumption. In this work we conduct a comprehensive study of energy and runtime tradeoff sin software transactional memory systems. We characterize the behavior of three state-of-the-art lock-based STM algorithms, along with three different conflict resolution schemes. As a result of this characterization, we propose a DVFS-based technique that can be integrated into the resolution policies so as to improve the energy-delay product (EDP). Experimental results show that our DVFS-enhanced policies are indeed beneficial for applications with high contention levels. Improvements of up to 59% in EDP can be observed in this scenario, with an average EDP reduction of 16% across the STAMP workloads. © 2012 IEEE.