Transplant data: sources, collection and research considerations, 2004

The process of collecting and analyzing transplant data is complex. Familiarity with how these data are collected is crucial to a thorough understanding of the information. This article focuses on available OPTN-SRTR data and the continuing evolution of data collection mechanisms; how that data collection system is improving the data quality and reducing the data collection burden; how additional ascertainment of outcomes both completes and validates existing data; and caveats that remain for researchers. This year's article focuses further on research considerations related to cohort choice, timing of data submission, and potential biases in follow-up data. Ongoing improvements in data collection timeliness and scope are covered. The impact of extra ascertainment of outcomes, particularly for post-transplant kidney graft failure from Medicare data, are also examined. A section on graft failure reporting among different sources traces the steps by which the SRTR reconciles different data sources in its analyses. It is important that those reading and conducting transplant research understand the origin, structure, and scope of the available data. All of these issues should be carefully considered when choosing cohorts and data sources for analysis.     

Structure function interface with sequential shortening of basal and apical components of the myocardial band

Objective: To mechanically test the intact cardiac structure to determine the sequence of contraction within the myocardial mass to try to explain ejection and suction. Methods: In 24 pigs (30–85 kg), segment shortening at the site of sonomicrometer crystals was continuously recorded. The ECG evaluated rhythm, and Millar pressure transducers measured intraventricular pressure and dP/dt. Results: Study of segment shortening defined a sequence of contraction within the myocardial mass, starting at the free wall of the right ventricle and on the endocardial side of the antero-septal wall of the left. Crystal location defined underlying contractile trajectory; transverse in right ventricle followed by basal posterior left ventricle, and from the endocardial anterior wall to the posterior apical segment and finally to the epicardial side of the anterior wall. Mean shortening fraction averaged 18±3%, with endocardial exceeding epicardial shortening by 5±1%. Epicardial segment crystal displacement followed endocardial shortening by 82±23 ms in the anterior wall, and finished 92±33 ms after endocardial shortening stopped, time frame that matches the interval of fast drop of ventricular pressure and the start of suction. Conclusions: Crystal shortening fraction sequence followed the rope-like myocardial band model to contradict traditional thinking, with two starting points of excitation–contraction, the right anterior free wall of the right ventricle, and the endocardial side of the anterior wall. Active suction may be due to active shortening of the epicardial fibers of the anterior wall, because relaxation was not detected when both mitral and aortic valves were closed during the interval previously termed ‘isovolumetric relaxation’.     

老年冠心病患者踝臂指数和心脏结构与功能的相关分析

目的探讨老年冠心病患者踝臂指数(ABI)和心脏结构与功能的相关性。方法87例老年冠心病患者,按ABI分组,A组ABI≤0.9,B组ABI>0.9,同时测量2组的心脏结构指标:左心房直径(LAD)、左心室舒张期直径(LVDD)、左心室后壁厚度(LVPW)。左室收缩功能指标:左室缩短率(FS)、左室射血分数(EF)。左室舒张功能指标:EF斜率。结果A、B2组比较,年龄、血脂、血糖、肝功能、肾功能、LAD、LVDD、LVPW和EF斜率均无显著性差异。FS和EF均有显著性差异,A组较B组明显降低(P<0.05)。结论ABI与老年冠心病患者的心脏功能有较好的相关性,对其预后的判定有一定的价值。     

阴茎包埋对海绵体内一氧化氮合酶的影响

目的:探讨阴茎包埋对海绵体内一氧化氮合酶(NOS)活性的影响。方法:通过建立大鼠隐匿阴茎模型获得实验标本,分2个月组、4个月组和6个月组进行观测,每组80只大鼠。各阶段中包括包埋组(n=50)、假手术组(n=15)和正常组(n=15)。称量大鼠体重和海绵体重量后,采用化学比色法检测海绵体内NOS活性。结果:各阶段包埋组阴茎海绵体重量、体重及两者的比值与正常组和假手术组比较均无显著性差异(P>0.05);包埋降低大鼠阴茎海绵体组织的NOS活性(2个月组P>0.05,4个月组P<0.05,6个月组P<0.01)。结论:阴茎包埋可影响海绵体内NOS活性,且与包埋时间呈正相关,但对海绵体外观和重量无明显影响。     

The end adjusts the means: Heterochromatin remodelling during terminal cell differentiation

All cells that constitute mature tissues in an eukaryotic organism undergo a multistep process of cell differentiation. At the terminal stage of this process, cells either cease to proliferate forever or rest for a very long period of time. During terminal differentiation, most of the genes that are required for cell ‘housekeeping’ functions, such as proto-oncogenes and other cell-cycle and cell proliferation genes, become stably repressed. At the same time, nuclear chromatin undergoes dramatic morphological and structural changes at the higher-order levels of chromatin organization. These changes involve both constitutively inactive chromosomal regions (constitutive heterochromatin) and the formerly active genes that become silenced and structurally modified to form facultative heterochromatin. Here we approach terminal cell differentiation as a unique system that allows us to combine biochemical, ultrastructural and molecular genetic techniques to study the relationship between the hierarchy of chromatin higher-order structures in the nucleus and its function(s) in dynamic packing of genetic material in a form that remains amenable to regulation of gene activity and other DNA-dependent cellular processes.     

Comparing orthodontic undergraduate student satisfaction with teaching in Leeds,UK and Marburg,Germany

A questionnaire was used to compare undergraduate student satisfaction with orthodontic teaching in two units; one in Leeds, UK, the other in Marburg, Germany. Whilst the methods of teaching differed between the units, the aim was to highlight aspects of both courses which students might wish to see improved. Statistical analysis suggested that students appreciate clarity of course structure and means of assessment and that use of a course manual is helpful in achieving this. Recommended texts to back-up course work are also appreciated whilst students from both locations, want to see more patients. Alternatives, such as patient case folders, computer-assisted learning packages and use of videos showing treatment progression, seem to be acceptable alternatives should there be difficulty in supplying “real” patients. The relevance of laboratory courses needs to be reviewed. Overall, the use of student questionnaires is seen as a useful tool in monitoring standards of teaching.     

胎盘血流量下降对大鼠胎仔生长和胎盘结构的影响——宫内生长迟缓动物模型的研究

本实验采用 SD 大鼠,在孕后期行孕鼠一侧子宫动脉中段完全结扎,另一侧作对照.23只孕鼠(150只胎仔)分成未结扎上、下(CU 和 CL)与结扎上、下(LU、LL)四组.结果表明,LU 组宫内胎仔体重、胎盘重、脑肝重均较其它三组有显著下降(P<0.01);LU 组脑/肝重比值及脑/体重比值较其它三组有显著增加(P<0.01).其胎仔呈不均称性宫内生长迟缓(IUGR)。52只胎盘作了光镜观察,12只胎盘作了电镜观察。在已知子宫胎盘血流不足,且胎仔发生 IUGR 的情况下,其胎盘的改变与以往报道的人类 IUGR 胎盘病理改变相一致,从而证实了子宫胎盘血流量下降是 IUGR 发病的重要原因之一。     

Simultaneous genetic analysis of longitudinal means and covariance structure in the simplex model using twin data

A longitudinal model based on the simplex model is presented to analyze simultaneously means and covariance structure using univariate longitudinal twin data. The objective of the model is to decompose the mean trend into components which can be attributed to those genetic and environmental factors which give rise to phenotypic individual differences and a component of unknown constitution which does not involve individual differences. Illustrations are given using simulated data and repeatedly measured weight obtained in a sample of 82 female twin pairs on six occasions.