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Shafik A El Sibai O Shafik AA 《Experimental biology and medicine (Maywood, N.J.)》2005,230(8):569-572
We have shown in previous studies that electric waves at rest could be recorded from the testicle and originate from the tunica albuginea (TA) and not from the testicular tissue. In the current study, we investigated the hypothesis that the electric activity of the TA increases during ejaculation. Three electrodes were sutured to the TAs of 11 anesthetized male dogs. The slow waves were recorded at rest and on inducing ejaculation by an ejaculator applied to the glans penis. Basal electric waves were recorded from the testicle. Each wave consisted of a negative followed by a positive deflection with a mean frequency of 6.2 +/- 1.3 cycles/min, an amplitude of 0.59 +/- 0.06 mV, and a conduction velocity of 5.2 +/- 0.8 cm/sec. These wave variables showed a significant intermittent increase (P < 0.05) at intervals of 0.6-1.0 secs and occurred simultaneously with the bouts of ejaculation. The increase remained for 0.8-1.2 secs at each ejaculation bout. The number of bouts of increased electric waves varied from 3 to 5. Apparently, the TA is not an inert covering to the testicle, but it seems to have a functional activity. Recording resting electric waves of the TA presumably denotes that the TA possesses a resting tone that appears to support the testicular tissue. During ejaculation, the increased electric activity of the TA, which coincides with semen spurt episodes, presumably denotes TA contraction. The intermittent TA contractions seem to assist in massaging the testicular secretions to the epididymis and the vas deferens and augment testicular circulation. The effect of pathologic conditions of the TA on ejaculation needs to be studied. 相似文献
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Local community participation and ex situ conservation has the potential to assist the recovery of the endangered Egyptian tortoise, Testudo kleinmanni. We initiated an in situ community‐based conservation and research program from a captive population of T. kleinmanni. We used a captive population of the Egyptian tortoise to train a member of the local community as a research technician and used his indigenous tracking skills and knowledge of the area to collect activity and dietary data on 28 captive tortoises. We overcame problems with illiteracy by creating a data sheet based on symbols and numbers. This data sheet allowed us to use the indigenous knowledge of various people from the community, and employ them in the future. Our local community approach to data collection, in conjunction with a craft program, made the conservation of the Egyptian tortoise more rewarding to the local community by providing a more sustainable form of income than collecting animals for the pet trade. Our multidimensional approach (local community participation as research technicians, craft program, and trust building) for gaining local support eventually led to the rediscovery of wild Egyptian tortoises in North Sinai, which was significant, as this species was presumed extinct in Egypt. We have now shifted our focus to in situ conservation, using the research and local capacity building template developed from this captive population study. Our template can be used by zoos and conservation organizations with small budgets and collections of native species in natural habitats to create similar captive research programs that can be applied to in situ conservation. Zoo Biol 26:397–406, 2007. © 2007 Wiley‐Liss, Inc. 相似文献
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Impact of abiotic factors on some biological indices of Cyprinus carpio (L., 1758) in Ghrib dam lake, (Algeria) 下载免费PDF全文
This study was conducted with a sample of 733 Cyprinus carpio collected between May 2013 and February 2016 from the ecosystem lake in the Ghrib dam which is eutrophic. Cyprinus carpio in this dam is characterized by a single fractional spawning that begins in the spring and ends in the late summer. The distributions of the viscerosomatic and gonadosomatic indices decrease between the spring and summer seasons. These periods correspond to the spawning period and the biological break of this species. They progressively increase between autumn and winter when the biological activity of the species returns. The hepatosomatic index progressively decreases between the spring and the summer when the hepatic reserves are used for reproduction. The repletion index shows that the trophic activity of C. carpio is intense in the spring. The condition factor varies between 1.1 and 1.35. The evolution of the biological indices of both sexes is well stressed in well‐defined periods according to the seasons. The values are weak for males and high for females. The redundancy analysis allows the characterization of the influence of the physico‐chemical parameters of the dam water, especially the role of the nutritious elements, in the biological seasonal cycle of C. carpio. 相似文献
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Powers RW Jeyabalan A Clifton RG Van Dorsten P Hauth JC Klebanoff MA Lindheimer MD Sibai B Landon M Miodovnik M;Eunice Kennedy Shriver National Institute of Child Health Human Development Maternal-Fetal Medicine Units Network 《PloS one》2010,5(10):e13263
Background
Differences in circulating concentrations of antiangiogenic factors sFlt1 and soluble endoglin (sEng) and the pro-angiogenic growth factor PlGF are reported to precede the onset of preeclampsia weeks to months in low-risk pregnant women. The objective of this study was to investigate whether similar changes can be detected in pregnant women at high-risk to develop the syndrome.Methods
This study is a secondary analysis of the NICHD MFMU trial of aspirin to prevent preeclampsia in high-risk pregnancies. Serum samples were available from 194 women with pre-existing diabetes, 313 with chronic hypertension, 234 with multifetal gestation, and 252 with a history of preeclampsia in a previous pregnancy. Samples collected across pregnancy were analyzed in a blinded fashion for sFlt1, sEng and PlGF.Results
The odds of developing preeclampsia were significantly increased among women with multiple fetuses for each 2-fold elevation in sFlt1, sEng and the ratio of angiogenic factors (e.g. OR 2.18, 95% CI 1.46-3.32), and significantly decreased for each 2-fold elevation in circulating PlGF (OR 0.50, 95% CI 0.30-0.82) between 7 and 26 weeks'' gestation. Cross-sectional analysis of the angiogenic factors across gestation showed significant differences during the third trimester in women who develop preeclampsia compared with appropriate controls in all high-risk groups. However, when data were examined in relation to the gestational week when preeclampsia was diagnosed only sFlt1 was significantly higher 2 to 5 weeks before the clinical onset of preeclampsia and only in women with previous preeclampsia.Conclusions
The pattern of elevated concentrations of sFlt1 and sEng, and low PlGF in high-risk pregnant subjects who develop preeclampsia is similar to that reported in low-risk pregnant women. However, differences in these factors among high-risk women who do and do not develop preeclampsia are modest, and do not appear to be clinically useful predictors in these high-risk pregnant women. 相似文献7.
M S Ahmed L W Randall B Sibai C Dass G Fridland D M Desiderio E Tolun 《Life sciences》1987,40(21):2067-2076
The human placental villus tissue contains opioid receptors and peptides. The opioid peptides extracted from the villus tissue were fractionated using reverse-phase high performance liquid chromatography and a radio-receptor assay. The presence of dynorphin 1-8 was corroborated by mass spectrometric production of (M + H) ion in the fast atom bombardment mode. This octa-peptide could be the natural ligand of the kappa opioid receptors present in the human placental villus tissue. 相似文献
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Emily F. Gliniewicz Kelly M. Chambers Elizabeth R. De Leon Diana Sibai Helen C. Campbell Kathryn A. McMenimen 《Proteins》2019,87(5):401-415
Small heat shock proteins (sHsps) are molecular chaperones employed to interact with a diverse range of substrates as the first line of defense against cellular protein aggregation. The N-terminal region (NTR) is implicated in defining features of sHsps; notably in their ability to form dynamic and polydisperse oligomers, and chaperone activity. The physiological relevance of oligomerization and chemical-scale mode(s) of chaperone function remain undefined. We present novel chemical tools to investigate chaperone activity and substrate specificity of human HspB1 (B1NTR), through isolation of B1NTR and development of peptide-conjugated gold nanoparticles (AuNPs). We demonstrate that B1NTR exhibits chaperone capacity for some substrates, determined by anti-aggregation assays and size-exclusion chromatography. The importance of protein dynamics and multivalency on chaperone capacity was investigated using B1NTR-conjugated AuNPs, which exhibit concentration-dependent chaperone activity for some substrates. Our results implicate sHsp NTRs in chaperone activity, and demonstrate the therapeutic potential of sHsp-AuNPs in rescuing aberrant protein aggregation. 相似文献
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Tim Newbold Tom Reader Ahmed El‐Gabbas Wiebke Berg Wael M. Shohdi Samy Zalat Sherif Baha El Din Francis Gilbert 《Oikos》2010,119(8):1326-1334
Species distribution models are a very popular tool in ecology and biogeography and have great potential to help direct conservation efforts. Models are traditionally tested by using half the original species records to build the model and half to evaluate it. However, this can lead to overly optimistic estimates of model accuracy, particularly when there are systematic biases in the data. It is better to evaluate models using independent data. This study used independent species records from a new to survey to provide a more rigorous evaluation of distribution‐model accuracy. Distribution models were built for reptile, amphibian, butterfly and mammal species. The accuracy of these models was evaluated using the traditional approach of partitioning the original species records into model‐building and model‐evaluating datasets, and using independent records collected during a new field survey of 21 previously unvisited sites in diverse habitat types. We tested whether variation in distribution‐model accuracy among species could be explained by species detectability, range size, number of records used to build the models, and body size. Estimates of accuracy derived using the new species records correlated positively with estimates generated using the traditional data‐partitioning approach, but were on average 22% lower. Model accuracy was negatively related to range size and number of records used to build the models, and positively related to the body size of butterflies. There was no clear relationship between species detectability and model accuracy. The field data generally validated the species distribution models. However, there was considerable variation in model accuracy among species, some of which could be explained by the characteristics of species. 相似文献
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Jeyabalan A Powers RW Clifton RG Van Dorsten P Hauth JC Klebanoff MA Lindheimer MD Sibai B Landon M Miodovnik M;Eunice Kennedy Shriver National Institute of Child Health Human Development Maternal-Fetal Medicine Units Network 《PloS one》2010,5(10):e13270