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.     

Immunoglobulin heavy chain Diversity genes rearrangement pattern indicates that MALT-type gastric lymphoma B cells have undergone an antigen selection process

Gastric MALT lymphoma usually develops from chronic gastritis, the vast majority of which (>90%) is associated with Helicobacter pylori infection. We sequenced the third complementarity determining region (CDR3) of immunoglobulin heavy chain genes in 19 gastric MALT lymphoma clones to determine the pattern of variable (V), diversity (D) and joining (J) gene utilization during immunoglobulin gene rearrangement.
DNA was extracted from paraffin-embedded sections and the rearranged CDR3 regions were amplified using a semi-nested polymerase chain reaction (with primers complementary to the conserved framework-three segment of the variable region [FR3A] and J regions). The DNA used for cloning and sequencing was obtained after purification of monoclonal bands excised from polyacrylamide gels. The N-D-N region specific to each clone was compared with known germline D sequences.
Similarly to that observed in normal and leukaemic B cells, our series of gastric MALT lymphomas showed apparent preferential utilization of genes from the DXP family. In two cases no similarity between the CDR3 nucleotide sequences of the neoplastic clones and the known germline D sequences could be found. In 10/19 analysed alleles the lymphoma B-cell clones appeared to contain two D gene segments (D-D recombination), a rare occurrence in normal individuals but one which has been described as a significant event in the determination of idiotype expression and antigen-binding affinity. Remarkably, despite the use of different D and J segments, the resultant amino acid sequences matched in two patients, suggesting the presence of a common selecting antigen.
The observed pattern of D gene rearrangement suggests that MALT lymphoma B-cell clones have undergone antigen selection, which seems to indicate that the antigen stimulation plays a pivotal role in the development of the lymphoma.     

针药并用治疗男性不育297例疗效分析

本文采用针刺加鹿茸精注射液穴位注射及中药治疗男性不育297例,痊愈142例,占47.8％,显效81例,占27.3％,有效53例,占17.8％,无效21例,占7.1％,三者联合运用效果较满意。     

Optimal Selection of Sib Pairs from Random Samples for Linkage Analysis of a QTL Using the EDAC Test

Percentages of extremely concordant and extremely discordant sib pairs are calculated that maximize the power to detect a quantitative trait locus (QTL) under a variety of circumstances using the EDAC test. We assume a large fixed number of randomly sampled sib pairs, such as one would hope to find in the large twin registries, and limited resources to genotype a certain number of selected sib pairs. Our aim is to investigate whether optimal selection can be achieved when prior knowledge concerning the QTL gene action, QTL allele frequency, QTL effect size, and background (residual) sib correlation is limited or absent. To this end we calculate the best selection percentages for a large number of models, which differ in QTL gene action allele frequency, background correlation, and QTL effect size. By averaging these percentages over gene action, over allele frequency, over gene action, and over allele frequencies, we arrive at general recommendations concerning selection percentages. The soundness of these recommendations is subsequently in a number of test cases.     

Laboratory screening method for selection of healthy volunteers

The aim of laboratory screening in Phase I is to exclude subjects with subclinical illness, who might be at increased risk in the study, and who might also adversely influence interpretation of the results. A new method for laboratory screening, based on Bayesian probability theory, is proposed, which consists of: 1. Drawing up a list of diseases to be excluded. 2. Defining for each disease, the maximum acceptable risk that an included subject could be affected by it. 3. Identifying one test for each disease. 4. Using a contingency table to calculate the specificity of the test and integrating the estimated prevalence of the disease from epidemiological data. 5. Applying the percentage obtained by the calculation of specificity to the previously determined distribution of values in the volunteer population to identify the threshold value for inclusion. Use of this deductive method in screening volunteers for Phase I trials affords increased security of selection, while reducing the number of non-pertinent exclusions because of laboratory findings.     

优选前后精子顶体酶活性与IVF受精率相关性的研究

目的探讨优选处理前和处理后精子顶体酶活性的变化,及与体外受精(IVF)受精率的相关性。方法采用分光光度比色法,对接受IVF治疗的53例不育夫妇男方精液,分别测定优选处理前和处理后精子顶体酶活性,分析其与IVF受精率的相关性。结果优选处理后精子顶体酶活性与优选前比较有显著性差异(P<0.05);达到常规IVF标准并选择常规IVF治疗者,优选后的精子顶体酶活性与IVF受精率有相关性,精子顶体酶活性降低与IVF受精率降低有关。结论精子顶体酶活性与IVF受精率有相关性,并且通过精子顶体酶活性可以预测IVF受精率。     

电脑比配色仪与比色板之间的相近性分析

目的：通过对比色记录的分析，比较Vita比色板、松风Vintage Halo比色板和电脑比配色仪之间的相近性和差异性。方法：随机抽取100名年龄在21～24岁的本地在校大学生，由男女两位测试者使用电脑比配色仪、Vita比色板和松风Vintage Halo比色板对被测试者的左上中切牙进行比色分析。结果：三种比色方法均以A色调最为集中，占总数的55％以上。其次是D色调占总数20％以上。男女测试者的选色在A、R、VR．系列中无明显差异。结论：电脑比配色仪、Vita比色板、松风Vintage Halo比色板均不能完全覆盖本地区青年天然中切牙的色度特征，只在A色调系列中重复率较高。     

He-Ne激光沿经络自动照射治疗仪的研制

介绍He-Ne激光沿经络自动照射治疗仪，它能使激光光束按人们所需要的强度，路径，方式沿经络进行自动照射。     

Signal-to-noise ratio effects in quantitative cerebral perfusion using dynamic susceptibility contrast agents.

Theoretical and simulation evidence is presented in support of the idea that the optimal manner of determining blood flow from MR perfusion studies is not necessarily obtained by setting experimental conditions to maximize either the arterial input or the measured tissue concentration level for a particular echo time (TE). The noise power in the contrast concentration curve is associated with its peak because of the nonlinear relationship between the contrast concentration and MR signal intensity curves. The optimum signal-to-noise ratio (SNR), SNR(C), for a particular contrast concentration curve can be obtained when the experimental concentration level and TE are adjusted to produce an MR intensity curve whose signal loss is 63% of the precontrast MR signal intensity. It is demonstrated that the stability of the singular valued decomposition (SVD) deconvolution approach to determine blood flow parameters is increased when the tissue curve maximum signal loss is in the range of 40-80%. The accuracy and stability of the SVD-determined blood flow parameters are affected by deviations from these optimum conditions in a manner that depends on the mean transit time (MTT) associated with the residue function. It is recommended that the experimental TE value be set so that neither the tissue nor the arterial curves are placed a region of rapidly deteriorating SNR(C).     

穴位综合疗法对先天愚型患者智商的影响

【目的】评价中医穴位疗法对先天愚型患者智商的影响。【方法】将80例先天愚型患者随机分为穴位综合疗法治疗组(简称综合治疗组)、脑复康对照组(简称脑复康组)、空白对照组,综合治疗组取四神针(百会穴前、后、左、右各旁开1.5寸)、智三针(神庭穴和左右本神穴)、颞三针(耳失直上2寸为第1针,左右旁开1寸为第2、3针)、脑三针(脑户穴及两侧脑空穴)为主穴,进行针刺和维生素B_(12)、维丁胶性钙、脑活素穴位注射,脑复康组口服脑复康,空白组不作任何特殊治疗;4个月为1个疗程,期间嘱家长在家对患儿进行相应的教育和训练;治疗前和疗程结束后采用 《中国修订韦氏儿童智力量表》测定患儿的智商(IQ),包括语言IQ(VIQ)、操作IQ(PIQ)和总IQ(FIQ)。【结果】4个月治疗后,综合治疗组总体智力水平均有提高(与空白组比较,均P<0.01),并较脑复康组为优;并且综合治疗组治疗后IQ的提高主要为PIO各项得分的提高所贡献,与操作有关的几个项目的得分与治疗前比,均有显著意义(P<0.05),而VIQ得分治疗后未见显著性提高(均P>0.05)。【结论】穴位综合疗法能提高先天愚型患者的智商。