均衡组间差异的有效方法:倾向评分

目的：实例介绍倾向评分法的基本原理和适用条件，设计适用于分析二分类资料的SAS宏程序。方法：运用倾向评分比较平衡前后两组间差异的改变情况，评价放弃心肺复苏急救与充血性心力衰竭患者院内死亡的联系。结果：采用分层法和匹配法都可以有效地平衡两组各个特征变量间所存在的高度差异，三种分析方法获得相近的估计结果。结论：倾向评分法是均衡组间差异的有效方法，能够匹配和平衡各个特征变量的作用，并用于分析各种观察性研究资料。     

基于Mapcheck2的调强放射治疗计划剂量验证分析

目的探讨基于Mapcheck2的调强放射治疗计划剂量验证与靶区均匀性指数(HI)、靶区适形指数(CI)及等中心点剂量梯度(D_Gref)的关系。方法选取2018年6月至2020年2月于医院行调强放射治疗计划的497例患者作为研究对象,采用Mapcheck2进行剂量验证,以剂量误差3%、吻合距离3 mm下的γ通过率≥90%且中心点累积剂量偏差绝对值(Dacc)≤3%为限定条件,在合格的462例计划中随机选取18例设为对照组,将不合格的35例分为A组(Dacc≤3%但γ通过率<90%,11例)、B组(γ通过率<90%且Dacc>3%,9例)、C组(γ通过率≥90%但Dacc>3%,15例),计算并比较4组的HI、CI及D_Gref值。结果 A组各指标与对照组比较,C组HI、CI值与对照组比较,差异均无统计学意义(P>0.05);B组各指标与对照组比较,C组D_Gref值与对照组比较,差异均有统计学意义(P<0.05)。对35例不合格计划进行优化设计后,经验证均合格,且优化后计划的HI、CI及D_Gref值与优化前比较,差异均无统计学意义(P>0.05)。结论调强放射治疗计划设计前,应选取合理的射野数目、方向,优化参数、算法,并尽量将射野等中心点置于靶区内剂量梯度较小的位置,以减少影响剂量验证的不良因素。     

耐碳青霉烯类鲍曼不动杆菌同源性研究

目的 探讨我院2001年8月～2002年3月显著增多的耐碳青霉烯类鲍曼不动杆菌之间的同源性。方法 用脉冲场凝胶电泳对7株耐碳青霉烯类鲍曼不动杆菌进行分型，明确其是否为同一菌株的克隆。结果 7株不动杆菌分为：A型2株，A1型2株，A2型1株。A1型与A2型之间的相似系数达94．6％，它们与A型的相似系数达84．9％，其余两株各有独特的PFGE分型。结论 其中5株耐碳青霉烯类鲍曼不动杆菌有高度同源性，第5号株极可能是此次院内感染的源头。     

Development of a lyophilized soybean paste certified reference material for the analysis of ochratoxin A

A certified reference material (CRM) [²KRISS CRM # 108-10-018] for the analysis of ochratoxin A (OTA) in doenjang (fermented soybean paste and popular food in Korea) was produced to ensure the reliability of analytical results in testing laboratories. A home-made doenjang was chosen as a raw material after testing its OTA level. The raw material was freeze-dried, pulverized, sieved and homogenized. An isotope-dilution-liquid chromatography/tandem mass spectrometric method (ID-LC/MS/MS) which was previously developed and validated in this laboratory was used as a higher-order reference method for characterization, homogeneity studies, and short-term stability studies. The CRM had good between-bottle homogeneity with 0.56% relative standard deviation among 10 selected units. The stability of the CRM at −70 °C (the storage condition in our laboratory) and at −20 °C (the possible storage temperature at user sites) were tested for up to 8 months. No change in the OTA content was observed within the measurement uncertainty. The stability of the CRM at room temperature (for regular use and transportation) was also tested and confirmed. The certified value was (49.50 ± 1.17) μg/kg, where the expanded uncertainty was in the confidence level of 95%.     

基于正则化的磁共振相控阵线圈图像均匀性校正算法

由于能提供更大的扫描视野,更高的信噪比和缩短扫描时间,相控阵线圈已经被广泛使用在磁共振成像(MRI)设备中。相控阵线圈的图像重建合成最常用的是SOS算法,但是SOS算法通常会造成图像的灰度不均匀。这样不仅会直接影响医生诊断的准确性,同时对图像自动分割等后处理技术的使用也会产生不良影响。本文提出一种改进的基于正则化的最小二乘化方法,用于MRI相控阵图像的合成。在该方法中利用均匀的大体线圈和相控阵线圈进行预扫描获得线圈敏感图,通过引入正则函数来控制重建图像的噪声。此外,在正则函数中还使用大体线圈的预扫描图像作为参考图像。使用水模和志愿者成像数据验证,该方法能够有效提高相控阵线圈重建图像的均匀性。     

动物血清替代人血清制备乙肝标志物室间质评物的初步研究

目的尝试制备以胎牛血清(FCS)替代人血清为基质的乙型肝炎病毒(HBV)标志物室间质评样本。方法以FCS作为基质稀释人血清HBV标志物高值样本制备室间质评样本,并对制备样本进行基质效应和互换性实验、均匀性和稳定性评估及初步临床应用。结果使用两种检测方法验证制备样本的可互换性,检测值分布于95%可信区间内,相关性很好。雅培i1000全自动免疫分析仪检测HBV 5个项目[乙型肝炎病毒表面抗原(HBsAg)、乙型肝炎病毒表面抗体(HBsAb)、乙型肝炎病毒e抗原(HBeAg)、乙型肝炎病毒e抗体(HBeAb)、乙型肝炎病毒核心抗体(HBcAb)]制备物结果的F值均F界值(F界值=3.02),保存于-20℃和4℃时可稳定1个月以上。20家使用化学发光法[ABBOTT i2000全自动免疫分析仪(简称ABBOTT i2000)]和20家使用酶免法(科华试剂)的实验室HBsAg、HBsAb、HBeAg、HBeAb、HBcAb的变异系数(CV)分别为ABBOTT i2000仪器组7.60%、7.79%、6.37%、13.30%、3.61%,科华试剂组11.67%、14.72%、9.11%、12.30%、9.75%。结论通过试验验证以FCS为基质制备的质评样本的互换性、稳定性和均匀性满足室间质评样本要求,初步认为FCS在一定程度上可以作为基质用于HBV标志物室间质评样本的制备。     

血细胞分析国家一级标准物质的研制

目的研制血细胞分析国家一级标准物质,作为血细胞分析检测结果溯源的标准。方法新鲜血经稳定化处理、调整浓度后分装成待评价的标准物质;参照ISO Guide35(2006版)和《一级标准物质技术规范》的要求进行均匀性和稳定性评价,使用直接溯源至参考方法的标准仪器对标准物质进行定值;对标准物质的均匀性、稳定性和定值过程引入的不确定度进行评定,计算合成不确定度和扩展不确定度;将一级标准物质与二级标准物质的不确定度进行比较。结果标准物质WBC、RBC、Hb和PLT4个参数的均匀性评价的方差分析结果均显示P0.05,表明标准物质是均匀的;瓶间均匀性的标准不确定度分别为0.04×109/L、0.022×1012/L、0.1g/L和2.2×109/L。26周内各参数的稳定性评价趋势分析结果均显示P0.05,表明该期限内标准物质是稳定的;长期稳定性的标准不确定度分别为0.08×109/L、0.023×1012/L、1.1g/L和3.6×109/L。定值结果的标准不确定度分别为0.09×109/L、0.059×1012/L、1.2g/L和4.1×109/L;合成并扩展不确定度后,定值结果表达式分别为(5.4±0.3)×109/L、(4.42±0.13)×1012/L、(137±3)g/L和(187±12)×109/L。一级标准物质各参数的不确定度均明显小于国家二级标准物质。结论标准物质的均匀性和稳定性良好,定值方法可靠;各参数定值结果的不确定度明显小于国家二级标准物质。     

Psychometric properties and factor structure of the Swedish version of the Perceived Stress Scale

Abstract

Background: The Perceived Stress Scale (PSS) measures general stress and the Swedish version, although used in several studies, has not been extensively evaluated for psychometric properties. Aims: This study aimed to investigate psychometric properties and the factor solution of the Swedish 14-item version when used with two samples, namely a mixed Internet sample of women and men (n = 171) and another of women with stress-related disorders (n = 84). Classical test theory, including confirmatory factor analysis, was employed. Results: The factor structure supported a two-factor model for the PSS and confirmed other language versions of the PSS, although one items showed a low item-total correlation. The PSS showed to be feasible with the investigated samples and the results indicated no ceiling or floor effects and good internal consistency of the PSS. Several aspects of construct validity were shown. An association of ? 0.66 between the PSS and a measure of coping indicated good concurrent validity. Criterion validity was demonstrated through a statistically significant difference (P < 0.001) between the women with stress-related disorders and the Internet sample. Predictive validity of the PSS could be demonstrated in a short-term perspective. Based on the sample with stress-related disorders, sensitivity to change was shown through a statistically significant stress reduction (P < 0.001) from entering work rehabilitation to discharge. Conclusions: The Swedish version of the PSS showed satisfactory psychometric properties and may be recommended for use with people with and without known stress-related disorders.     

均质性肺气肿经支气管镜单向活瓣肺减容术研究

目的探索经支气管镜单向活瓣肺减容术对均质性肺气肿的治疗效果。方法均质性肺气肿Beagle犬7只,在动物右肺经支气管镜置入2～4枚支气管单向活瓣,2个月后处死实验动物,进行大体标本观察,光镜病理学评价及电子计算机图像定量分析,并与基本情况相似的正常犬和肺气肿模型犬进行比较,评价疗效。结果共置入21枚活瓣,除2枚活瓣咳出外,余19枚活瓣均未移位。实验动物无明显不良反应。观察大体标本发现单向活瓣阻塞的肺叶缩小、质地较硬,脏层胸膜有局灶瘢痕形成,支气管壁周围有少许组织增生;周围肺叶无出血、实变。病理学观察及图像分析结果示7只实验犬被阻塞的肺叶均有中度肺泡炎及肺间质纤维化表现。图像定量分析结果显示,与肺气肿模型犬比较,7只实验犬有明显肺泡陷闭、肺容积缩小表现（P〈0.01）,与正常犬比较也有肺泡陷闭、肺容积缩小表现（P〈0.05）。结论单向活瓣肺减容术对均质性肺气肿犬的治疗在一定程度上是有效的。     

Development and characterization of a new thief sampling device for cohesive powders

New sampling probes and methods for investigating cohesive powders are conceived, designed and characterized. Probes are made of two metallic shells (a slide and a cover) which need to be inserted sequentially into the bed of powder in order to extract representative samples. The thin profile of the shells, combined with a particular insertion procedure, is intended to minimize stresses on the powder; thereby reducing both the invasiveness and the dragging of material through the bed. Probes of similar design with different shape and size have been tested on stratified beds of cohesive powders of different colors. Sampling performances are quantitatively compared among different probes (for size and shape) and also with literature data. The comparison has indicated that the new sampling devices effectively improved sampling efficiency, reliability and possibilities. The simple construction and use suggest they can be viable and effective alternatives to traditional probes for cohesive mixtures.