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排序方式: 共有279条查询结果,搜索用时 15 毫秒
41.
Frederico Ozanan Barros Monteiro Leandro Nassar Coutinho Eliane do Socorro de Souza Pompeu Paulo Henrique Gomes de Castro Celsemy Eleutério Maia Washington Luis Assunção Pereira Wilter Ricardo Russiano Vicente 《International journal of primatology》2009,30(2):327-336
We evaluated the uterus and ovaries of owl monkeys (Aotus azarai infulatus) via gynecological ultrasound examination. We evaluated the subjects in 2 different time periods. The first period (P1) was
characterized by the absence of mating, with daily examinations, during 4 mo (n = 10). At the end of P1, we paired the subjects for 30 d, but without ultrasonographic evaluation. The second period (P2)
was characterized by the presence of mating, with examinations once a week, during 7 consecutive months (n = 9). We evaluated the uterus and ovaries in sagittal and transverse scans, using a 5–12 MHz linear array probe. The uterine
volume (UV) was directly proportional to the number of previous parturitions. The right ovary volume (RtOV) is greater than
the left (LtOV) in P1 and P2. There is a positive correlation (p < 0.05) between the females’ mass, RtOV (r = 0.28) and LtOV (r = 0.16). 相似文献
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Agave cocui (Agavaceae) is a species with broad distribution in arid and semiarid areas of Venezuela and Colombia. Despite of its ecological importance as a source of food for wildlife, and its economic value for production of a spirit drink, studies on the reproductive ecology of the species are relatively rare. In this study, we conducted a one-year evaluation of the flowering and fruiting phenology of A. cocui in the eight representative localities of the species' distribution in Venezuela. Within each study site, we chose an area with a minimum of 50 reproductive individuals and followed their reproductive phenophases with the help of binoculars, using six qualitative cathegories (emerging reproductive stalk, flowers, inmature fruits, mature fruits, bulbils and dry stalk) every two months. Emergence of the reproductive stalk in most of the examined populations began in September (rainy season), although this event delayed two months in a few populations. We detected significant negative correlations between precipitation and the percentage of flowering occurrence in four of the eight populations. Floral resources are available for flower visitors during approximately five months of the year (January-May). In most populations production of flowers initiated in January (dry season), and for Western Venezuela and Andean regions, the flowering main peak occurred in January. Localities from the Central and Eastern Coast exhibited the flowering peak in March, showing a delay of approximately two months with respect to other populations. Beginning of fruit set varied among localities from January to May; however, peak production of mature fruits concentrated in May, and fruit occurrence varied broadly between 5.2 and 85%. Bulbil production was detected in all populations and varied greatly among them (maximum percentage per population: 26.19-92.10%). High flowering synchronicity (Phenophase Overlapping Index: 0.756 and 0.999) was observed among all populations monitored in Western Venezuela, including the Andean localities. This condition might facilitate the existence of a nectar corridor from the Western Coast and nearby islands, to the Andean arid patches, which could be potentially used by nectar-feeding bats and birds dependent on agave flowers during part of the year. 相似文献
44.
San Luis B Sondgeroth B Nassar N Carpino N 《The Journal of biological chemistry》2011,286(18):15943-15954
T cell activity is controlled in large part by the T cell receptor (TCR). The TCR detects the presence of foreign pathogens and activates the T cell-mediated immune reaction. Numerous intracellular signaling pathways downstream of the TCR are involved in the process of T cell activation. Negative regulation of these pathways helps prevent excessive and deleterious T cell responses. Two homologous proteins, Sts-1 and Sts-2, have been shown to function as critical negative regulators of TCR signaling. The phosphoglycerate mutase-like domain of Sts-1 (Sts-1(PGM)) has a potent phosphatase activity that contributes to the suppression of TCR signaling. The function of Sts-2(PGM) as a phosphatase has been less clear, principally because its intrinsic enzyme activity has been difficult to detect. Here, we demonstrate that Sts-2 regulates the level of tyrosine phosphorylation on targets within T cells, among them the critical T cell tyrosine kinase Zap-70. Utilizing new phosphorylated substrates, we demonstrate that Sts-2(PGM) has clear, albeit weak, phosphatase activity. We further pinpoint Sts-2 residues Glu-481, Ser-552, and Ser-582 as specificity determinants, in that an Sts-2(PGM) triple mutant in which these three amino acids are altered to their counterparts in Sts-1(PGM) has substantially increased activity. Our results suggest that the phosphatase activities of both suppressor of TCR signaling homologues cooperate in a similar but independent fashion to help set the threshold for TCR-induced T cell activation. 相似文献
45.
Antonio Paulo Nassar Junior Alberto Queiroz Farias Luiz Augusto Carneiro d’ Albuquerque Flair José Carrilho Luiz Marcelo Sá Malbouisson 《PloS one》2014,9(9)
Background
Hepatorenal syndrome (HRS) is a severe and progressive functional renal failure occurring in patients with cirrhosis and ascites. Terlipressin is recognized as an effective treatment of HRS, but it is expensive and not widely available. Norepinephrine could be an effective alternative. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of norepinephrine compared to terlipressin in the management of HRS.Methods
We searched the Medline, Embase, Scopus, CENTRAL, Lilacs and Scielo databases for randomized trials of norepinephrine and terlipressin in the treatment of HRS up to January 2014. Two reviewers collected data and assessed the outcomes and risk of bias. The primary outcome was the reversal of HRS. Secondary outcomes were mortality, recurrence of HRS and adverse events.Results
Four studies comprising 154 patients were included. All trials were considered to be at overall high risk of bias. There was no difference in the reversal of HRS (RR = 0.97, 95% CI = 0.76 to 1.23), mortality at 30 days (RR = 0.89, 95% CI = 0.68 to 1.17) and recurrence of HRS (RR = 0.72; 95% CI = 0.36 to 1.45) between norepinephrine and terlipressin. Adverse events were less common with norepinephrine (RR = 0.36, 95% CI = 0.15 to 0.83).Conclusions
Norepinephrine seems to be an attractive alternative to terlipressin in the treatment of HRS and is associated with less adverse events. However, these findings are based on data extracted from only four small studies. 相似文献46.
A Haj-Yehia T Nassar B S Sachais A Kuo K Bdeir A B Al-Mehdi A Mazar D B Cines A A Higazi 《FASEB journal》2000,14(10):1411-1422
We examined the effect of urokinase (uPA) and its fragments on vascular smooth muscle cell contraction. Single-chain uPA inhibits phenylepherine (PE) -induced contraction of rat aortic rings, whereas two-chain uPA exerts the opposite effect. Two independent epitopes mediating these opposing activities were identified. A6, a capped peptide corresponding to amino acids 136-143 (KPSSPPEE) of uPA, increased the EC(50) of PE-induced vascular contraction sevenfold by inhibiting the release of calcium from intracellular stores. A6 activity was abolished by deleting the carboxyl-terminal Glu or by mutating the Ser corresponding to position 138 in uPA to Glu. A single-chain uPA variant lacking amino acids 136-143 did not induce vasorelaxation. A second epitope within the kringle of uPA potentiated PE-induced vasoconstriction. This epitope was exposed when single-chain uPA was converted to a two-chain molecule by plasmin. The isolated uPA kringle augmented vasoconstriction, whereas uPA variant lacking the kringle had no procontractile activity. These studies reveal previously undescribed vasoactive domains within urokinase and its naturally derived fragments. 相似文献
47.
Error-driven learning rules have received considerable attention because of their close relationships to both optimal theory and neurobiological mechanisms. However, basic forms of these rules are effective under only a restricted set of conditions in which the environment is stable. Recent studies have defined optimal solutions to learning problems in more general, potentially unstable, environments, but the relevance of these complex mathematical solutions to how the brain solves these problems remains unclear. Here, we show that one such Bayesian solution can be approximated by a computationally straightforward mixture of simple error-driven ‘Delta’ rules. This simpler model can make effective inferences in a dynamic environment and matches human performance on a predictive-inference task using a mixture of a small number of Delta rules. This model represents an important conceptual advance in our understanding of how the brain can use relatively simple computations to make nearly optimal inferences in a dynamic world. 相似文献
48.
Hassen Gherbi Emile Duhoux Claudine Franche Katharina Pawlowski Atef Nassar Alison M. Berry Didier Bogusz 《Physiologia plantarum》1997,99(4):608-616
We have characterized a full-length cDNA ( hb -Cg1F) that represents symbiotic mRNA hemoglobin ( hb ) from Casuarina glauca root nodules. In situ hybridization was used to examine the correlation between hb -Cg1F mRNA and the state of the Frankia infection process. The efficiency of in situ hybridization using DIG-labeled vs [35 S]-labeled probes was compared. The expression of hb -Cg1F gene is induced in young infected host cells prior to the detection of Frankia nif H mRNA. Since Frankia does not form vesicles in C. glauca nodules, it is proposed that Hb is necessary to reduce the O2 concentration in the cytoplasm of the host cells before the nif genes are expressed. 相似文献
49.
50.
ATL-derived exosomes modulate mesenchymal stem cells: potential role in leukemia progression 总被引:1,自引:0,他引:1