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.     

HCV的检测方法

从发现丙型肝炎病毒以来 ,丙肝的检测技术发展迅速 ,灵敏度和特异性都有明显的提高 ,方法学在不断改进完善。笔者就近年来丙型肝炎的实验室检测方法作简要的综述     

无名异接骨冲剂对骨痂局部骨形态发生蛋白含量的影响

为探讨无名异接骨冲剂加速骨折愈合的作用机理，选用５５只新西兰大白兔，随机选择５只作为正常组；另５０只在无菌条件下造成双桡骨标准骨折模型。将５０只骨折兔随机平均分为实验组和对照组，实验组用无名异接骨冲剂每天４ｇ／ｋｇ溶于２０ｍｌ蒸馏水中分早晚两次灌胃；对照组用２０ｍｌ蒸馏水灌胃。于骨折后第１，２，３，４及５周用断颈法每次每组处死５只兔，取骨痂进行抗骨形态发生蛋白（ＢＭＰ）单克隆抗体免疫组化染色，并用ＣＭＩＡＳ型图像分析仪对ＢＭＰ含量进行定量分析。结果发现：实验组骨折局部ＢＭＰ含量明显高于正常组（Ｐ＜０．０１）；第１，２周实验组明显高于对照组（Ｐ＜０．０１）；实验组ＢＭＰ高峰出现在第２周，而对照组出现在第３周。认为，无名异接骨冲剂能促进成骨细胞合成ＢＭＰ，使ＢＭＰ峰值提前，从而加速骨折愈合。     

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.     

Quantitative study of the morphological changes in the thyroid gland following IR laser radiation

The morphological changes produced in the thyroid glands of albino rats following radiation with a 904 nm infrared laser were studied. Two different levels of radiation were applied: 46.8 J/cm² and 140.4 J/cm². Evaluation of the changes in the densities of the epithelial, colloidal and follicular volumes and of the activation index revealed that the laser beam produced changes in the thyroid parenchyma. It was observed that there was a direct relationship between the severity of the lesion and the radiation energy applied.     

The composite N1 component to gaps in noise.

OBJECTIVE: To indicate whether the double peaked N(1) to gaps in continuous white noise is a composite of onset and offset responses to transients or whether it reflects higher processing such as change or mismatch detection and to assess the role of attention in this process. METHODS: Evoked potentials were recorded to two binaural stimulus types: (1) gaps of different durations randomly distributed in continuous white noise; and (2) click pairs at intervals identical to those between gap onsets and offsets in the continuous noise stimulus. Potentials to these stimuli were recorded while subjects read a text and while detecting gaps in noise or click pairs. RESULTS: Potentials were detected to all click pairs and to gaps of 5 ms or longer, corresponding to the subjects' psychoacoustic gap detection threshold. With long gap durations of 200-800 ms, distinct potentials to gap onset and gap offset were observed. The waveforms to all click pairs and to offsets of long gaps were similar and single-peaked, while potentials to gaps of 10 ms and longer, and potentials to onsets of long gaps were double-peaked, consisting of two N(1) negativities, 60 ms apart, irrespective of gap duration. The first (N(1a)), was more frontal in its distribution and similar to that of clicks. The second (N(1b)) peak's distribution was more central/temporal and its source locations and time course of activity were distinct. No effects of attention on any of the varieties and constituents of N(1) were observed. CONCLUSIONS: Comparing potentials to gap onsets, to click pairs and to gap offsets, suggests that potentials to gap onsets involve not only sound onset/offset responses (N(1), N(1a)) but also the subsequent pre-attentive perception of the cessation of an ongoing sound (N(1b)). We propose that N(1b) is distinct from change or mismatch detection and is associated with termination of an ongoing continuous stimulus. We propose to call it the N(egation)-process. SIGNIFICANCE: A constituent of the N(1) complex is shown to be associated with the pre-attentive perception of termination of an ongoing stimulus and to have distinct scalp distribution and intracranial sources.     

Understanding capture detection.

Automatic capture detection systems are currently available in several cardiac pacing devices. All current systems use low-polarization electrodes and no beat to beat detection system is available for all types of electrodes. In addition the success ratio for currently available systems is not always 100%. Failure to detect capture reliably is often related to the behaviour of the electrode-tissue interface under different circumstances. Pacemaker electrodes can be considered electrochemical cells with complicated characteristics depending on time, temperature and electrical charge. This electrochemical cell is disturbed when a charge is transferred across the electrode-tissue interface during pacing. Several measures can be taken in order to minimise this disturbance or pace polarization artefact (PPA) including the use of high active surface area electrodes and application of tri-phasic pacing pulses. Another factor influencing detection of evoked potentials is the input circuit of the pacemaker affecting the PPA and the evoked response. Positive PPAs can be falsely interpreted as evoked potentials due to the undershoot of the second order filters applied in modern cardiac pacemakers. This paper explains the behaviour of the interface between the electrode and the cardiac tissue in combination with the pacemaker output circuits and input amplifiers under different circumstances.     

简单灵敏的免疫复合物抗原特异性固相酶联检测法

本文将聚乙二醇(PEG)比浊法和固相酶联免疫法(ELISA)结合,建立了—较灵敏的免疫复合物(IC)直接固相吸附抗原特异性检测法。利用牛清蛋白(BSA)为已知抗原组份的IC模型,分别对IC直接固相吸附的条件和影响因素、方法的灵敏度、重复性等进行了研究。结果发现IC在解离状态下直接固相吸附后的抗原特异性检测灵敏度明显高于未解离者。该法具有简单易行,灵敏度较高、适于临床测定大量血清样品等优点。     

用化学发光自显影技术快速检测鸭沙门氏菌

应用我室建立的化学发光自显影技术检测鸭沙门氏菌。用酶标抗体与硝酸纤维素膜上固定的细菌结合,再同发光底物溶液作用,使X线胶片感光,根据胶片上的黑斑进行半定量,可检出100个菌。其检测特异性好,约2小时即可出报告。     

Increased in vitro uptake of the complement C3b in the serum of patients with Guillain-Barré syndrome, myasthenia gravis and dermatomyositis

To examine the role of complement in certain autoimmune neuromuscular diseases, we used an in-vitro quantitative complement uptake assay that allows measurement of the capacity of patients' sera to deposit fragments of the third complement component onto sensitized targets. C3 uptake was significantly higher in patients with active dermatomyositis, Guillain-Barré syndrome and myasthenia gravis, compared to inclusion body myositis and controls. The in-vitro C3 uptake assay supports the role of C3b neoantigen and Membranolytic Attack Complex deposition in the target tissues and may be a useful tool to monitor disease activity in patients with complement-mediated neurological disorders.