Utility of Tissue Similarity Maps Based on Relative Cerebral Blood Volume for Grading Gliomas as Validated by Histological Results

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生命早期抗生素使用与儿童哮喘:因果关系还是混杂效应?

儿童哮喘的发病率逐年上升.基于卫生假说,抗生素使用可能减少了微生物暴露,从而增加了过敏性疾病发生的风险.近十年来,就早期抗生素暴露与儿童哮喘的关系进行的大量的流行病学调查的结果并不一致.大多数回顾性研究发现正相关联系,但前瞻性研究未发现联系或联系强度较弱.逆向因果和指示混淆可部分解释两者的关系,但也难以否定因果关系的存在.     

Population Genetics Identifies Challenges in Analyzing Rare Variants

Geneticists have, for years, understood the nature of genome‐wide association studies using common genomic variants. Recently, however, focus has shifted to the analysis of rare variants. This presents potential problems for researchers, as rare variants do not always behave in the same way common variants do, sometimes rendering decades of solid intuition moot. In this paper, we present examples of the differences between common and rare variants. We show why one must be significantly more careful about the origin of rare variants, and how failing to do so can lead to highly inflated type I error. We then explain how to best avoid such concerns with careful understanding and study design. Additionally, we demonstrate that a seemingly low error rate in next‐generation sequencing can dramatically impact the false‐positive rate for rare variants. This is due to the fact that rare variants are, by definition, seen infrequently, making it hard to distinguish between errors and real variants. Compounding this problem is the fact that the proportion of errors is likely to get worse, not better, with increasing sample size. One cannot simply scale their way up in order to solve this problem. Understanding these potential pitfalls is a key step in successfully identifying true associations between rare variants and diseases.     

10对联体双胎分离术后的远期结果

背景／目的：从1978-2000年，有10对联体双胞胎成功接受了手术分离，结果14人存活。其中6对是因为他们的联体同胞死亡或濒临死亡而接受紧急分离手术。剩余的4对，每对至少一个同胞接受至少一次的急诊手术后，才接受联体分离手术。方法：对这一独特的队列进行包含6个项目的问卷调查。问题的设计是开放式的，为父母／家庭提供有关信息的最大机会。对每个家庭就相同的问题也进行了当面的问卷调查。医师询问了与身体健康和疾病相关的一些问题。而社会工作询问了与发育、教育、社会心理和家庭功能相关的问题。结果：前面提及的14人存活的双胞胎中，4人大学毕业，1人于1981年完成中学学业，剩余9人正在上学。14人在最初的手术后，还需要接受再次手术，尤其是需要矫正泌尿系统、畸形、神经外科和小儿外科的问题。结论：通过超声检查对联体双胎进行宫内诊断，可以使医师和胎儿父母在孕早期决定在终止妊娠时是进行双胎分离还是保全其中一个。这些病例报道通过描述14例手术存活的长期体格检查和心理学检查结果，为医师和父母在关键时刻做出决定提供了另外有助的依据。     

血浆血栓素B2和6-酮-前列腺素F1α水平与新生儿窒息关系

为观察不同程度窒息新生儿血浆血栓素B2(TXB2)和6-酮-前列腺素F1α(6-Keto-PGF1α)含量变化及其规律,选择对照组20例,轻度窒息组19例,重度窒息组21例,均在生后6 h内取股静脉血2 ml,进行放射免疫分析.结果TXB2及其与6-Keto-PGF1α比值在对照组分别为(202.42±53.91)pg/ml、1.81±0.61,轻度窒息组分别为(646.29±121.66)pg/ml、3.73±1.27,重度窒息组分别为(1443.27±254.61)pg/ml、6.83±2.39,三组方差分析,组间差异有显著性(F值分别为286.19,49.78,P＜0.001);6-Keto-PGF1α升高,三组分别为(117.22±33.14)Pg/ml、(184.73±52.65)pg/ml、(223.45±63.48)pg/ml(P＜0.05).提示窒息新生儿血浆TXB2和6-Keto-PGF1α含量及两者之比明显升高,重度窒息组比轻度窒息组升高明显;与对照组相比,其升高程度与窒息程度有关.