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排序方式: 共有278条查询结果,搜索用时 15 毫秒
71.
目的:研究父母的母语为非英语的婴儿比父母的母语为英语的婴儿是否更不易接受推荐的预防性医疗行为。研究设计:笔者对1999年1月1日至2000年9月30日期间在华盛顿州出生的所有38793例参加医疗救助的1岁婴儿进行回顾性组群研究。主要因素为自己报告的父母的母语。笔者使用多参数回 相似文献
72.
Characterization of susceptible chiasma configurations that increase the risk for maternal nondisjunction of chromosome 21 总被引:17,自引:4,他引:17
Lamb NE; Feingold E; Savage A; Avramopoulos D; Freeman S; Gu Y; Hallberg A; Hersey J; Karadima G; Pettay D; Saker D; Shen J; Taft L; Mikkelsen M; Petersen MB; Hassold T; Sherman SL 《Human molecular genetics》1997,6(9):1391-1399
Recent studies of trisomy 21 have shown that altered levels of
recombination are associated with maternal non-disjunction occurring at
both meiosis I (MI) and meiosis II (MII). To comprehend better the
association of recombination with nondisjunction, an understanding of the
pattern of meiotic exchange, i.e. the exchange of genetic material at the
four-strand stage during prophase, is required. We examined this underlying
exchange pattern to determine if specific meiotic configurations are
associated with a higher risk of non-disjunction than others. We examined
the crossover frequencies of chromosome 21 for three populations: (i)
normal female meiotic events; (ii) meiotic events leading to MI
non-disjunction; and (iii) those leading to MII non-disjunction. From these
crossover frequencies, we estimated the array of meiotic tetrads that
produced the observed crossovers. Using this approach, we found that nearly
one-half of MI errors were estimated to be achiasmate. The majority of the
remaining MI bivalents had exchanges that clustered at the telomere. In
contrast, exchanges occurring among MII cases clustered at the
pericentromeric region of the chromosome. Unlike the single exchange
distributions, double exchanges from the non-disjoined populations seemed
to approximate the distribution in the normal population. These data
suggest that the location of certain exchanges makes a tetrad susceptible
to non- disjunction. Specifically, this susceptibility is associated with
the distance between the centromere and closest exchange. This result
challenges the widely held concept that events occurring at MII are largely
independent of events occurring at MI, and suggests that all
non-disjunction events may be initiated during MI and simply resolved at
either of the two meiotic stages.
相似文献
73.
Kiewe P; Bechrakis NE; Schmittel A; Ruf P; Lindhofer H; Thiel E; Nagorsen D 《Annals of oncology》2006,17(12):1830-1834
Background: Metastatic uveal melanoma has a poor prognosis andlimited therapeutic options. Proteoglycans are involved in tumorcell invasion and metastatic behavior. The mAbB5 stains a chondroitinsulphate proteoglycan (CSPG) on cutaneous melanoma cells. Here,we compare the B5-staining of CSPG in primaries and metastasesof uveal melanoma. Material and methods: Immunohistopathological staining was performedin 15 cutaneous and 39 uveal melanoma samples. A score for intracellularand surface staining was established. B5 staining was comparedin primaries and metastases of uveal melanoma using Student'st-test. Results: Eight of 11 (73%) uveal melanoma metastases were positivefor B5-staining whereas only 5 of 28 (18%) primary uveal melanomasamples were B5-positive (P < 0.001). Nine of 15 cutaneousmelanoma samples (60%) were B5-positive without significantdifference between primary and metastatic lesions. Surface stainingwas found both on uveal melanoma metastases and cutaneous melanomas. Conclusions: CSPG was expressed significantly more often inmetastases than in primaries of uveal melanoma. It potentiallymay be one factor associated with metastatic spread. Furtherstudies are needed to determine its use as prognostic factor.The mAbB5 may also be a promising tool for immunotherapy dueto its strong staining of CSPG on the surface of cutaneous andmetastatic uveal melanoma cells. Key words: uveal melanoma, ocular melanoma, chondroitin sulphate proteoglycan, immunotherapy, immunohistochemistry 相似文献
74.
HLNE JACQMIN-GADDA DANIEL COMMENGES CHAKIB NEJJARI JEAN-FRANOIS DARTIGUES 《Statistics in medicine》1997,16(11):1283-1297
We propose a test of correlation of the residuals in generalized linear models which is a generalization of the spatial autocorrelation test based on Moran's I. It allows adjustment for sizes of geographical areas and for explanatory variables. A formula is given to compute the weights according to the alternative hypothesis. We compare inference using the distribution in the model and using the permutation distribution. A simulation study showed that the model-based test may be very conservative and this leads to a loss of power compared to the permutation test or to the model-based test with correction for estimated parameters. As this latter is intractable for very large samples when the model includes explanatory variables, we recommend the use of the permutation test. The permutation test is used to study geographical correlation of dyspnoea in the elderly. © 1997 by John Wiley & Sons, Ltd. 相似文献
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77.
Iu P Nikitin E V Klochkova E K Iadryshnikova D A Shakalis L P Shelu'dko 《Kardiologiia》1989,29(9):34-38
The paper presents the data on dietary habits, blood lipid composition, and prevalence of coronary heart disease in native and non-native populations from Buryatia. They were obtained by using epidemiological (assessment of amounts of the food ingredients consumed) and biochemical (measurement of blood levels of total cholesterol, triglycerides, and high density lipoprotein cholesterol) methods. Differences were demonstrated in dietary habits between the native and non-native populations from Buryatia. The differences were shown to be associated with the prevalence of dyslipoproteinemias and coronary heart disease in these population groups. 相似文献
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