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An RNA-binding motif (RBM) gene family has been identified on the human Y chromosome that maps to the same deletion interval as the 'azoospermia factor' (AZF). We have identified the homologous gene family (Rbm) on the mouse Y with a view to investigating the proposal that this gene family plays a role in spermatogenesis. At least 25 and probably >50 copies of Rbm are present on the mouse Y chromosome short arm located between Sry and the centromere. As in the human, a role in spermatogenesis is indicated by a germ cell-specific pattern of expression in the testis, but there are distinct differences in the pattern of expression between the two species. Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are female due to a position effect resulting in non-expression of Sry ; sex-reversing such mice with an Sry transgene produces males with a high incidence of abnormal sperm, making this the third deletion interval on the mouse Y that affects some aspect of spermatogenesis. Most of the copies of Rbm map to this deletion interval, and the Yd1males have markedly reduced Rbm expression, suggesting that RBM deficiency may be responsible for, or contribute to, the abnormal sperm development. In man, deletion of the functional copies of RBM is associated with meiotic arrest rather than sperm anomalies; however, the different effects of deletion are consistent with the differences in expression between the two species.   相似文献   
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Purpose To characterize and predict cycles generating slowcleaving embryos in in vitro fertilization, 86 cycles were retrospectively divided into two groups (slow, n=41, and fast, n=45 according to whether the number of blastomeres per embryo on day 3 was or > than the mean of the distribution, respectively.Results Cycles generating slowcleaving embryos were treated with luteinizing hormonereleasing hormone agonist before ovarian stimulation for a shorter period (12.1±0.5 versus 15.6±1.1 days; P0.01) and had higher immaturity grade of oocyte-corona-cumulus complexes which resulted in embryos (1.6±0.1 vs 1.3±0.1; P0.05) when compared to cycles producing fastcleaving embryos. Both variables entered in a logistic regression model applied in order to predict the probability of a cycle generating slowcleaving embryos (goodness-of-fit chisquare=180.0, degrees of freedom (df)=80, P=0.4786. This model predicted correctly 86.7% (13 of 15) of cycles generating slowcleaving embryos and 83.3% (10 of 12) of cycles producing fastcleaving embryos when the estimated probability of a cycle producing slowcleaving embryos was 0.7 or 0.3, respectively.Conclusion Shorter treatment with hormone-releasing hormone agonist before ovarian stimulation and higher immaturity grade of oocyte-corona-cumulus complexes which result in embryos are predictive characteristics of in vitro fertilization cycles generating slow-cleaving embryos.  相似文献   
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End-stage periventricular leukomalacia: MR evaluation   总被引:3,自引:0,他引:3  
Baker  LL; Stevenson  DK; Enzmann  DR 《Radiology》1988,168(3):809-815
A prospective study was performed to assess the capabilities of magnetic resonance (MR) imaging in evaluation of end-stage periventricular leukomalacia (PVL) in six children, aged 31-54 months, in whom PVL had been documented by neurologic ultrasonography during the neonatal period. Eight children of similar age (four premature infants and four full-term infants) with normal neurologic development served as controls. A characteristic triad of PVL abnormalities was seen on MR images: (a) abnormally increased periventricular white-matter signal intensity on the first and second echo images of a T2-weighted sequence (repetition time = 2,000-2,400 msec, echo times = 20 or 30 and 80 msec), most commonly observed in the trigone regions of the lateral ventricles bilaterally; (b) marked loss of periventricular white matter in these regions of abnormal signal intensity, predominantly in the periatrial regions; and (c) compensatory focal ventricular enlargement adjacent to regions of abnormal signal intensity. In patients with the classic periatrial distribution of PVL lesions, general correlation between the degree of neurologic impairment and the severity of MR abnormalities was demonstrated. MR imaging was useful in detecting subtle forms of PVL in cases in which neurologic damage was subclinical.  相似文献   
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