How many subjects are needed in a longitudinal birth cohort study?

One of the first decisions that needs to be taken when planning a birth cohort concerns the size of the study. This in turn will depend on the research questions to be answered and thence whether environmental exposures and outcomes are measured on a continuum or as dichotomous variables. Here we describe ways in which different birth cohorts have addressed this issue and explore the advantages of smaller detailed studies over larger less-detailed studies.     

CT、MRI对肾上腺病变的诊断分析

目的:分析探讨CT、MRI诊断对肾上腺病变的作用与价值。方法:MarconiMX8000 4层螺旋CT机,增强造影剂使用非离子型制剂,常规扫描及增强。应用西门子MAGNETOM1.5T磁共振机,增强造影剂使用Gd-DTPA制剂,常规T1WI、T2WI、脂肪抑制、化学位移同反相位及增强。对25例经手术及病理资料诊断证实的肾上腺病变进行CT、MRI诊断回顾性分析。结果:可清楚显示肾上腺病变的侧别、数目、大小、范围及可能的性质。结论:CT是肾上腺病变最佳影像检查方法,MRI具有重要辅助及补充诊断价值。     

Image technique optimization in MR imaging of a titanium alloy joint prosthesis

The purpose of this study was to explore systematically the effect of the imaging parameters changeable by the user in spin-echo (SE) imaging sequences to minimize image distortion when imaging joint prostheses. A titanium alloy hip joint prosthesis was studied at 1.0 T. The SE imaging parameters were bandwidth/pixel (BW/p), TE, strength of encoding gradients (matrix size), echo train length (ETL), and direction of phase and frequency encoding. The effect of ETL in rapid acquisition relaxation enhanced (RARE) sequences was also evaluated with a turbo-SE sequence using a different ETL with the same TR and an effective TE. It is concluded that an optimized image quality can be achieved in SE imaging by using a high bandwidth/pixel value (at least 130 Hz/pixel), a high resolution matrix (256–512), sequences with multiple refocusing, and a frequency-encoding axis parallel to the long axis of the prosthesis. The degree of distortion is reduced with this optimized technique.     

Selection of Single Nucleotide Polymorphisms for Association Studies in Candidate Genes

Comparison of polymorphic sites such as single nucleotide polymorphisms (SNPs) within a gene between cases and controls may be useful for establishing a role of this gene in disease susceptibility. The approach includes two steps: the first step is the discovery of the different SNPs within the candidate gene and the second step is the association testing per se that can be done on the entire set of sites discovered or on a subset of these sites only. Selecting a subset of sites may increase the power to detect the association with the candidate gene since a smaller number of tests would then be performed. We proposed a strategy to select sites within a candidate gene and applied it on the Genetic Analysis Workshop 12 candidate gene data. Using these selected sites, we detected an association with candidate genes 1 and 6. © 2001 Wiley‐Liss, Inc.     

核因子-κB与创伤的关系及其在法医病理学中的应用

损伤时间推断是法医病理学的一个研究热点和难点。核因子-κB(NF-κB)是一种核转录调节蛋白,参与多种炎性介质的转录和调控。近年来研究发现NF-κB与机体创伤后的反应密切相关,其在损伤后的时序性表达可望在法医病理学用于损伤时间推断。     

Multidimensional analysis of metabolism contributions involved in running track tests

It is difficult to interpret the training induced changes in middle-distance running, since numerous aerobic and anaerobic determinants of the performance are interdependent. Several aerobic and anaerobic tests are available but their results, particularly those from anaerobic tests, may be discordant, not providing univocal interpretation of training. The purpose of this study is to use a multidimensional approach to distinguish aerobic and anaerobic capacities assessed by two running tests on a track: the maximal anaerobic running test (MART) and V(O2max) tests. Eleven runners carried out two maximal tests on a synthetic track before and after a 4-week training period: (i) a maximal test to determine V(O2max), the velocity associated with V(O2max) (vV(O2max)) and the velocity at the lactate threshold (v(LT)), (ii) a maximal anaerobic running test to estimate anaerobic capacity. An all-out test run at v(LT)+50% of the difference between v(LT) and vV(O2max), known to be affected by both aerobic and anaerobic energy production, was used to test this approach. A principal components analysis (PCA) shows that two components (i.e., aerobic and anaerobic) explained 79% of the variation in the physiological variables. The PCA suggests that V(O2max) and MART tests assess the aerobic and the anaerobic capacities, respectively. In contrast, the performance in the all-out test is affected by both aerobic and anaerobic energy production. The PCA shows that v(LT) and DeltaP (difference between the maximal power of the MART and V(O2max)) are clear markers of the long-term endurance and the anaerobic capacity, respectively. This multidimensional approach can be a useful way to disentangle the aerobic and anaerobic components of track tests.     

National intercomparisons of I radioactivity measurements in nuclear medicine centres in India

National intercomparisons of activity measurements of ¹³¹I, a radioisotope widely used for diagnosis and therapy of thyroid related ailments, were initiated in 1979 as a quality assurance program, towards improving radiation safety procedures and related dosimetry in Nuclear Medicine Centres (NMCs) in India. Oral administration of a known quantity of radioiodine to patients requires accurate radioactivity measurements to be performed on a well-calibrated isotope calibrators. Under or over estimation of the activity due to a faulty or uncalibrated isotope calibrator could provide misleading results. Calibration of isotope calibrators and the traceablity of subsequent measurements to the national standards laboratory is one of the essential basic radiation safety requirement of the IAEA. In view of the stringent quality assurance requirements for activity measurements imposed by Atomic Energy Regulatory Board, a National Intercomparison Program was initiated and to date ten such intercomparison programs have been conducted by the Radiation Safety Systems Division, of the Bhabha Atomic Research Centre. This program has benefited the participants by making their measurements traceable to the National Primary Standards. Over the years there has been a marked increase in the number of NMCs participating in the intercomparison programs. As a result, the number of institution showing large deviation from the correct value has decreased considerably over the years. This program thus, has enabled participating NMCs to check their isotope calibrators so as to ensure proper delivery of radiation dose to the patients and hence to optimise patient exposure.     

Ethyl-EPA in Huntington disease—Potentially relevant mechanism of action

The pathomechanisms involved in the neuronal dysfunction in Huntington disease (HD) are still unresolved and may be heterogeneous. One potential mechanism might be related to the induction of mitochondrial dysfunction in the CNS. This might lead firstly to neuronal dysfunction and finally to the activation of apoptotic pathways. Several compounds, which should alleviate mitochondrial dysfunction, have been tested in preclinical models as well as in clinical trials of different scale. Recently we reported the efficacy of Ethyl-eicosapentaenoic acid (Ethyl-EPA) in patients with HD. Ethyl-EPA is a polyunsaturated fatty acid from the n − 3 group, which is in clinical development for HD and melancholic depression. In our trial with Ethyl-EPA in HD responding patients could be characterized by either a lower CAG repeat number or a chorea-predominant clinical expression of the disease. Here we would like to describe some evidence on the potential mechanism of action of Ethyl-EPA in HD. We specifically focus on pathways, which are known to be influenced in HD and are modified by Ethyl-EPA and which points to an involvement of mitochondrial function as a common target. Some attention is given to the NF-kappa B pathway and the c-Jun amino-terminal kinases (JNK) pathway, which both may lead to an activation of the antiproliferative factor p53 and consequently mitochondrial dysfunction. Further the effects of EPA or Ethyl-EPA in preclinical models of HD are described. The evidence from these studies led to the design of phase III clinical trials, which are ongoing.     

A treadmill test of sprint running

Anaerobic power is characterized by a high degree of specificity regarding both the recruited muscles as well as the recruitment pattern. The popular Wingate Anaerobic Test (WAnT) is a cycling test that does not satisfy the need for a running-specific anaerobic test. We describe such a test, using a novel type of a commercially available treadmill (BRL 1800, Gymrol, France). The ergometer is equipped with a torque motor to neutralize the frictional resistance of the treadmill belt, and a hip-belt harness connected to a horizontal rod. Force applied to the harness is monitored by a strain gauge mounted on the rod, while vertical movement is monitored by a potentiometer at the posterior fixed end of the rod. These, in conjunction with the treadmill belt speed, enable the computation of horizontal and vertical power as well as the combined total output. Power is calculated both as 'peak' power (highest 2.5 s segment) and 'mean' power (20 s duration). Preliminary results of young athletes were generally consistent with the expected age-related changes in anaerobic power. Values obtained on the anaerobic treadmill were always higher than the corresponding WAnT values previously obtained in comparable age groups. The higher values were probably due to the larger muscle mass involved and the shorter peak and mean power durations (2.5 and 20 s versus 5 and 30 s in the WAnT, respectively). This test should enable not only running-specific anaerobic power monitoring but also the characterization of the relationship between the horizontal and vertical components of that power.     

使用电力载波技术实现中央控制电子钟

本文应用电力载波技术，实现远端时钟的中央控制。系统通过电力载波芯片从电力线上收发控制信号，中央控制端发送的时钟校准信号到电力线网络，接人网络的远端时钟接收到校准信号后，由微处理器解析数据调整受控端时钟显示，从而实现时钟的中央控制。