Working‐correlation‐structure identification in generalized estimating equations

Selecting an appropriate working correlation structure is pertinent to clustered data analysis using generalized estimating equations (GEE) because an inappropriate choice will lead to inefficient parameter estimation. We investigate the well‐known criterion of QIC for selecting a working correlation structure, and have found that performance of the QIC is deteriorated by a term that is theoretically independent of the correlation structures but has to be estimated with an error. This leads us to propose a correlation information criterion (CIC) that substantially improves the QIC performance. Extensive simulation studies indicate that the CIC has remarkable improvement in selecting the correct correlation structures. We also illustrate our findings using a data set from the Madras Longitudinal Schizophrenia Study. Copyright © 2008 John Wiley & Sons, Ltd.     

基质金属蛋白酶和细胞因子在强直性脊柱炎骨破坏中的作用

强直性脊柱炎(ankylosing spondylitis,AS)是以中轴关节慢性炎症为主的原因不明的全身性免疫性疾病。其特点为几乎全部累及骶髂关节,常发生椎间盘纤维环及其附近韧带钙化和骨性强直,也可累及外周关节并造成关节软骨及骨的破坏,晚期可发生脊柱及外周关节强直、畸形以致严重功能受损[1]。所以我们必须强调重视AS骨质破坏发生机制的研究,有利于寻找有效药物,减少致残。1骶髂关节炎组织学研究较系统的骶髂关节炎组织学研究表明,AS的5个阶段不同程度存在滑膜炎、骨髓黏液样变、浅表软骨破坏、肌腱端炎、关节内纤维赘、新骨形成和骨性强直等众多病理表现;其中滑膜炎和软骨下骨髓黏液样变较肌腱端炎更能合理解     

Biochemical analysis of human milk treated with sodium dodecyl sulfate, an alkyl sulfate microbicide that inactivates human immunodeficiency virus type 1.

Reduction of transmission of human immunodeficiency virus type 1 (HIV-1) through human milk is needed. Alkyl sulfates such as sodium dodecyl sulfate (SDS) are microbicidal against HIV-1 at low concentrations, have little to no toxicity, and are inexpensive. The authors have reported that treatment of HIV-1-infected human milk with < or = 1% (10 mg/mL) SDS for 10 minutes inactivates cell-free and cell-associated virus. The SDS can be removed with a commercially available resin after treatment without recovery of viral infectivity. In this article, the authors report results of selective biochemical analyses (ie, protein, immunoglobulins, lipids, cells, and electrolytes) of human milk subjected to SDS treatment and removal. The SDS treatment or removal had no significant effects on the milk components studied. Therefore, the use of alkyl sulfate microbicides to treat milk from HIV-1-positive women may be a simple, practical, and nutritionally sound way to prevent or reduce transmission of HIV-1 while still feeding with mother's own milk.     

Modified Nile red staining method for improved visualization of neutral lipid depositions in stratum corneum.

The neutral lipids existing in the intercellular spaces of the stratum corneum (SC) provide a permeability barrier to prevent water loss. Nile red is the most sensitive lipid stain for tissue sections. However, due to the extremely flattened morphology of corneocytes and the resolution limits of the light microscope, Nile red staining is seldom used as a fluorescent probe for the lipid-rich SC. In this study, we modified the traditional method for visualization of intracellular lipid by adding 4% potassium hydroxide after Nile red staining. This modified method not only allowed visualization of lipids existing in the intercellular membrane regions and the lateral junctions of the adjoining corneocytes, but also clearly demonstrated small lipid droplets within pathological corneocytes. These features were not observed with the traditional staining method. Thus, this modified Nile red staining method greatly improved the resolution of the SC lipids under light microscopy and should be useful for studying lipid depositions in both normal and pathological SC.     

Le Fort型骨折的CT表现和分型

目的探讨Le Fort型骨折的CT表现及其分型。方法对62例Le Fort型骨折患者进行薄层螺旋CT扫描和三维重组分析。结果在62例中，Le FortⅠ型10例，Ⅱ型9例，Ⅲ型8例，复合型35例（其中Ⅰ＋Ⅱ型18例，I＋Ⅱ＋Ⅲ型7例，Ⅱ＋Ⅲ型10例）；55例同时伴发颌面部其他骨折。Le Fort型骨折在二维CT上表现为颌面部多发且杂乱的骨折，虽然在发现细小和深部结构的骨折方面优于三维CT成像，但难以作出Le Fort型骨折的诊断；三维CT成像能清晰立体地显示Le Fort型骨折的整体形状及走向，并可明确作出分型。结论三维CT成像是Le Fort型骨折最有效的诊断方法，对临床制定治疗方案具有指导意义，但是对细小骨折诊断不如二维CT。     

可吸收性医用珊瑚人工骨的致突变性研究

目的评价珊瑚人工骨的遗传毒性。方法采用Ames试验;细胞染色体畸变试验和小鼠骨髓细胞微核试验。结果不同浓度的浸提液加与不加S9mix条件下Ames试验;细胞染色体畸变试验以及微核试验与阴性对照组比较无显著差异,结果为阴性。结论在本试验系统条件下,可吸收性珊瑚人工骨无致突变作用。     

外加磁场对半乳糖化白蛋白磁性阿霉素纳米粒在大鼠体内分布影响的研究

目的观察半乳糖化白蛋白磁性阿霉素纳米粒(ADR-GHMN)在正常肝脏中的靶向性,并观察ADR-GHMN在全身各脏器的分布特征及外加磁场对其分布的影响.方法大鼠正中开腹,肝动脉插管并固定,肝动脉注射125I-ADR-GHMN(相当于阿霉素0.5 mg/kg),左外叶加磁场,磁场应用30 min,移去磁场后,动物立即处死;对照组:肝动脉注射ADR-GHMN,左外叶不加磁场,30min后,移去磁场后,动物立即处死,立即取靶区肝、非靶区肝、肾、心、肺、小肠、脾及周围血作γ计数.肝组织作病理切片.结果注入的纳米粒75～85%分布于肝脏,其它脏器极少.病理切片显示磁区小动脉见大量纳米粒存在,对照组及非磁区肝中纳米粒很少见.结论ADR-GHMN在正常肝组织中有明显的磁靶向性;在磁场作用下,ADR-GHMN主要分布于肝脏,其它脏器含量很少;试验组肾、心、肺、小肠、脾及外周血于对照组的放射活性比较明显降低,表明磁性物质的存在使这些脏器的相对药物暴露明显减少.