偏心圆剥离法在隆乳术中的应用

以往以乳头为圆心的同心圆剥离法常形成假体的移位，使假体的体表轮廓与前方的自然乳房分离，产生“双重乳房”现象。在研究了女性不同体位下不同的乳房形态及总结了以前的经验后，提出了偏心圆剥离的概念。偏心圆手术设计方法：以乳头为圆心，按其内侧、下侧为直径３／５的比例，以外侧、上侧为直径２／５的比例，形成一偏心圆的剥离范围。偏心圆的直径因考虑到假体的不同形态、大小及底面直径，以经中心假体纵截面的周长的１／２再放大２ｃｍ，作为剥离范围的直径。自１９９１年１０月以来已应用了１７６例，无一术后移位现象，也没有固较多地剥离胸大肌内、下侧止点纤维而影响上肢活动。自然乳房并不是静态的圆锥形或半球形，它具有伸缩的组织学特点，又有随体位变动而变化的特点。用偏心圆法剥离，可使置入的假体与前方的自然乳房融为一体，消除“双重乳房”现象，而成为“真实”的乳房。同时也应积极寻找一种与身体组织相容性好的，弹性、比重与女性乳腺较为一致的，假体容量相对恒定的生物性材料。这样隆乳术才可以更广泛地开展。     

Latent variable discovery in classification models

The naive Bayes model makes the often unrealistic assumption that the feature variables are mutually independent given the class variable. We interpret a violation of this assumption as an indication of the presence of latent variables, and we show how latent variables can be detected. Latent variable discovery is interesting, especially for medical applications, because it can lead to a better understanding of application domains. It can also improve classification accuracy and boost user confidence in classification models.     

遗传因素在乳头状甲状腺癌发生中的作用

目的探讨遗传因素在乳头状甲状腺癌(PTC)发生中的作用.方法采用以医院为基础的病例对照家系研究设计,采用Greenwood-Yule法和Haldane-Smith法,对172例PTC先证者及18例患PTC的亲属进行出生顺序分析.比较先证者一、二级亲属和一般人群的患病率,并进行零截尾负二项分布拟合检验,分析PTC是否具有家族聚集性.结果Greenwood-Yule法的分析结果显示,PTC出生顺序的实际分布与期望分布相近,各出生顺序的实际数与期望数的比值在1范围波动,表明PTC与出生顺序无关.Haldane-Smith法计算得C=|∑6A实际值-∑6A理伦值|/√∑V6A=0.567,P＞0.05,实际值与期望值的差异无统计学意义,亦表明PTC与出生顺序无关.PTC患者的一、二级亲属和人群患病率分别为1.08%、0.42%和0.09%,其中,一、二级亲属患病率的差异有统计学意义(x2=4.07,P=0.044),二级亲属与人群患病率的差异亦有统计学意义(Fisher P=0.046),PTC患病率存在一级亲属＞二级亲属＞一般人群的规律.零截尾负二项分布拟合检验结果表明,PTC在家系中的分布符合零截尾负二项分布(x2=0.13,P＞0.05),PTC的发生存在家族聚集性.结论遗传因素可能是PTC的主要危险因素,PTC可能是一种多因子遗传病.     

某非随机干预性研究偏倚风险评估工具及使用方法的解读

随着循证护理学的不断发展及非随机干预性护理研究的广泛应用,护理科研工作者需要在试验设计及证据采纳过程中对试验项目的 偏倚风险及整体质量作出评价以提高证据的质量.ROBINS-I(Risk of Bias in Non-randomized Studies-of Interventions)是目前值得推荐的非随机干预性研...     

AML患者外周血中TCR Vβ亚家族naive T细胞的检测

目的 检测急性髓性白血病(AML)患者外周血中TCR 23个Vβ亚家族的T细胞受体删除DNA环(sjTRECs)的存在特点,从而间接了解AML患者相应Vβ亚家族naive T细胞的近期胸腺输出情况.方法利用半巢式PCR分别扩增32例AML患者每5×104和1×104个外周血单个核细胞(PBMCs)中的23个Vβ亚家族sjTRECs,10例正常人外周血作为对照.结果在5×104和1×104两种PBMCs水平,AML患者检出sjTRECs的Vβ亚家族数分别为(5.09±3.28)和(2.59±2.06)个,与正常人的(13.70±2.67)和(5.50±2.07)个相比,两组的差异均有统计学意义(两组均为P=0.000).AML患者5×104个PBMCs中约可检测到5/23(20%)个Vβ亚家族sjTRECs,并且有13个Vβ亚家族sjTRECs的检出率明显低于正常人水平,其中Vβ10-和Vβ14-Dβ1 sjTRECs的检出率最低,而Vβ21最高.不同FAB分型AML患者间的检出差别未显示出统计学意义.32例AML患者检出sjTRECs的Vβ亚家族数量差别较大(1～15个),年龄与检出的亚家族数量呈负相关,＜30岁者的检出量高于≥30岁者,尤其在5×104个PBMCs水平差异有统计学意义(r=-0.481,P=0.005).结论 AML患者胸腺近期输出的23个Vβ亚家族naive T细胞存在不同程度的缺失或水平降低,表明AML患者存在严重的细胞免疫功能缺陷以及T细胞谱系重建的能力和潜能严重受损.     

Translational paradigms in pharmacology and drug discovery

The translational sciences represent the core element in enabling and utilizing the output from the biomedical sciences and to improving drug discovery metrics by reducing the attrition rate as compounds move from preclinical research to clinical proof of concept. Key to understanding the basis of disease causality and to developing therapeutics is an ability to accurately diagnose the disease and to identify and develop safe and effective therapeutics for its treatment. The former requires validated biomarkers and the latter, qualified targets. Progress has been hampered by semantic issues, specifically those that define the end product, and by scientific issues that include data reliability, an overt reductionistic cultural focus and a lack of hierarchically integrated data gathering and systematic analysis. A necessary framework for these activities is represented by the discipline of pharmacology, efforts and training in which require recognition and revitalization.     

Research participation effects: a skeleton in the methodological cupboard

ObjectiveThere have been concerns about impacts of various aspects of taking part in research studies for a century. The concerns have not, however, been sufficiently well conceptualized to form traditions of study capable of defining and elaborating the nature of these problems. In this article we present a new way of thinking about a set of issues attracting long-standing attention.Study Design and SettingWe briefly review existing concepts and empirical work on well-known biases in surveys and cohort studies and propose that they are connected.ResultsWe offer the construct of “research participation effects” (RPE) as a vehicle for advancing multi-disciplinary understanding of biases. Empirical studies are needed to identify conditions in which RPE may be sufficiently large to warrant modifications of study design, analytic methods, or interpretation. We consider the value of adopting a more participant-centred view of the research process as a way of thinking about these issues, which may also have benefits in relation to research methodology more broadly.ConclusionResearchers may too readily overlook the extent to which research studies are unusual contexts, and that people may react in unexpected ways to what we invite them to do, introducing a range of biases.     

A systematic review classifies sources of bias and variation in diagnostic test accuracy studies

ObjectiveTo classify the sources of bias and variation and to provide an updated summary of the evidence of the effects of each source of bias and variation.Study Design and SettingWe conducted a systematic review of studies of any design with the main objective of addressing bias or variation in the results of diagnostic accuracy studies. We searched MEDLINE, EMBASE, BIOSIS, the Cochrane Methodology Register, and Database of Abstracts of Reviews of Effects (DARE) from 2001 to October 2011. Citation searches based on three key papers were conducted, and studies from our previous review (search to 2001) were eligible. One reviewer extracted data on the study design, objective, sources of bias and/or variation, and results. A second reviewer checked the extraction.ResultsWe summarized the number of studies providing evidence of an effect arising from each source of bias and variation on the estimates of sensitivity, specificity, and overall accuracy.ConclusionsWe found consistent evidence for the effects of case–control design, observer variability, availability of clinical information, reference standard, partial and differential verification bias, demographic features, and disease prevalence and severity. Effects were generally stronger for sensitivity than for specificity. Evidence for other sources of bias and variation was limited.