Sperm chromatin integrity in young men with no experiences of infertility and men from idiopathic infertility couples

Damage to the genetic component of spermatozoa seems to play the main role in a majority of cases where current approaches fail to reveal the specific cause of male infertility. In this study, we compared semen quality in men assigned to two defined groups: men from couples with unexplained infertility – idiopathic infertility (A) and young men with no experiences of infertility (B). All samples were examined by standard ejaculate analysis and sperm chromatin structure assay (SCSA). Sperm chromatin damage was significantly higher in men from group A than in those from group B. Similar results were obtained by comparison of men from group A (all men were normozoospermic) with normozoospermic men from group B. According to these results, we can suppose that chromatin disorders may be the causal factor of subfertility or infertility in some of these men. No evidence for a strong association between chromatin disorders and standard parameters of ejaculates was found. We failed to confirm a relationship between smoking and sperm quality in men from any of the investigated groups. SCSA is a method that facilitates the identification of infertile men who otherwise show normal semen variables.     

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.     

化学实验进行开放式教学的研究

通过与传统的化学实验教学模式的比较，详述了开放式教学模式的特点，并且针对实施过程中所遇到的问题提出了详尽的解决方案。     

一种识别蛋白质的保守氨基酸残基的新方法

保守氨基酸残基在生物进化过程中具有较强的稳定性,一般不会发生太大的变化;生物信息学认为：氨基酸序列决定蛋白质结构,蛋白质结构决定蛋白质功能。因此,作者基于氨基酸的生化特性、几何特性和动态特性描述了一个新颖的算法去发现蛋白酶家族中的保守氨基酸残基,而保守氨基酸残基将对蛋白质的结构和功能的研究具有重要的意义。     

新型经皮渗透促进剂的研究进展

介绍国内外近年来报道的新型经皮渗透促进剂的研究与开发进展,重点介绍若干具代表性的新合成的化合物以及新发现的天然产物,包括内酰胺类、糖苷类、氨基酸衍生物、聚合物、挥发油和酶类等,为合成和发现更加安全、高效的促渗剂提供线索.     

地尔硫卓的合成

重点介绍了地尔硫的化学合成和拆分方法，以及近年来在其不对称合成领域的进展。     

替硝唑葡萄糖注射液的稳定性研究

采用反相ＨＰＬＣ法测定替硝唑葡萄糖注射液中替硝唑的含量，用加温加速实验研究该制剂的热稳定动力学。结果表明，替硝唑的热降解反应为一级动力学过程，在５０、６５、８０、９５℃时的降解速度常数分别为５．５８×１０－４、２．６６×１０－３、８．１０×１０－３、２．８２×１０－２ｄ－１，为８．３年，半衰期为３９．５年。     

Ridge number density: A new parameter for in vivo bone structure analysis

An advanced analysis of the mechanical properties of bone should include information about the microarchitecture of cancellous bone in addition to its density. It has recently been shown that high-resolution quantitative computed tomography and magnetic resonance imaging have the potential to assess such information in a noninvasive way in patients. Both techniques, however, lack sufficient spatial resolution to image the individual trabeculae with true precision. In this work, a new parameter, Ridge number density (RND), is introduced. RND is a measure for the trabecular number, which can be extracted directly from high-resolution three-dimensional (3D) images of patients. We applied the RND technique to a test group of nine healthy, postmenopausal women measured repetitively with a high-resolution 3D peripheral quantitative computed tomography (3D-pQCT) system with 165 × 165 × 165 μm³ voxel size. Simultaneously with the RND determination, the trabecular bone density (TBD) was also assessed in the same volume of interest. The examination site was the distal radius. The intersubject variability of the measured test group was 10.5% for RND and 26.3% for TBD. The root mean square error between first and second examinations (midterm reproducibility) was 1.6% and 1.1%, respectively. RND is determined independently from TBD and pertains to the structure of the cancellous bone. As such, it might add crucial information in cases where bone mass or bone density measurements alone give ambigous results.     

N-ω-Carbethoxypentyl-4-quinolones: A New Class of Leukotriene Biosynthesis Inhibitors

6-[(4-Quinolinyl)oxy]hexanoic acids and the corresponding esters were designed and synthesized as inhibitors of the production of arachidonic acid metabolites. The inhibitory activities were assayed in vitro by evaluation of serum leukotriene B₄ and thromboxane B₂ production. While all 6-[(4-quinolinyl)oxy]hexanoic acids and their esters proved to be inactive, the N-alkyl-4-quinolones, obtained as by-products in their synthesis, were found to be a new class of leukotriene biosynthesis inhibitors.     

对碘树脂型净水器产品结构与杀菌效果关系的探讨

近几年，我国对以碘树脂进行供水终端消毒作了一些研究，并有商品投放市场。这类产品杀菌效果除与所填充的碘树脂本身杀菌性能有关外，与产品结构也有很大关系。结构不同，水中微生物通过净水器的时间（即消毒作用时间）也将不同。经推导：消毒作用时间与碘树脂柱长度、直径以及碘树脂颗粒大小、填充数量、出水量大小等有关。因此，在产品结构设计时，可通过调整上述各参数，获得最佳杀菌效果。本文通过对这类产品结构与杀菌效果关系的探讨，为有关企业及部门合理设计产品内部结构提供了新思路。