Sharper Confidence Intervals for Hochberg- and Hommel-Related Multiple Tests Based On an Extended Simes Inequality

This article concerns recent developments related to the now classical multiple-testing procedures (MTPs) of Holm, Hochberg, and Hommel based on marginal p-values. For a long time, the derivation of simultaneous confidence intervals (SCIs) corresponding to these MTPs was considered to be a difficult problem, but solutions were published in 2008 for Holm's MTP, and in 2012 for Hochberg's and Hommel's MTPs. These SCIs turned out to be as simple and easily implemented as the MTPs themselves, and to be remarkably similar. However, they also turned out to have the property/limitation, shared with other powerful stepwise MTPs, that no confidence assertions sharper than rejection assertions are possible unless all null hypotheses are rejected. A possibility is then to construct related families of MTPs that do not have this limitation but are somewhat less powerful, so users may choose among various such trade-off MTPs. It is shown in this article how an extended Simes inequality can be used to construct Hochberg- and Hommel-related MTPs of this kind that: (i) are more powerful than corresponding trade-off MTPs proposed previously, and (ii) lead to SCIs that are sharper than the ones proposed previously. Corresponding Holm-related MTPs and SCIs are considered for completeness and comparisons.     

BECKMAN DxI800全自动化学发光仪甲状腺检测项目的性能验证

目的 评价BECKMAN DxI 800全自动化学发光仪甲状腺检测项目（TT3、TT4、FT3、FT4、TSH）的分析性能.方法参照美国临床实验室标准化协会（CLSI）文件,对BECKMAN DxI 800全自动化学发光仪检测TT3、TT4、FT3、FT4、TSH的精密度、线性范围及生物参考区间等方面进行验证,并与厂商声明的性能标准进行比较.结果 批内和批间精密度即变异系数（CV）均小于厂家声明的CV值,均在允许范围内;线性范围验证结果显示,各检测项目的 斜率（a值）均在（1±0.05）范围内,相关系数（r值）≥0.975,均在仪器要求范围内,并具有良好的线性;生物参考区间与厂商提供的性能指标相符.结论 BECKMAN DxI 800全自动化学发光仪5项甲状腺检测在精密度、线性范围及生物参考区间三个性能指标上,均在相关要求范围内,符合实验室要求,可应用于临床检测.     

Inferences on the mean response in a log-regression model: the generalized variable approach

This paper proposes a novel approach for the confidence interval estimation and hypothesis testing of the mean response in a log-regression model using the concept of generalized variable. Simulation studies demonstrate that the proposed confidence intervals have satisfying coverage probabilities. The proposed approach can be simply carried out by a few simulation steps. Therefore, it is an ideal candidate for making inferences about the mean response in a log-regression model.     

Impact of mercury exposure on blood pressure and cardiac autonomic activity among Cree adults (James Bay, Quebec, Canada)

Aboriginal populations from Quebec (Canada) are exposed to higher mercury levels than southern regions since these populations consume high quantities of fish. Epidemiological evidence suggests a detrimental impact of mercury on cardiovascular risk factors such as heart rate variability (HRV) and blood pressure (BP). The objective of this study was to assess the impact of mercury exposure on BP, resting heart rate (HR) and HRV among Cree adults. Data were collected among 791 adults ≥18 years old living in seven communities of the James Bay. Blood mercury and hair levels were used as biomarkers of recent and long-term exposure. BP was measured through a standardised protocol while HRV was derived from a 2-h Holter monitoring assessment. The relationship between mercury and the outcomes was studied using ANOVA and ANCOVA analysis. Geometric mean of blood mercury and hair mercury concentration was 17.0 nmol/L (95%CI: 6.1–44.0) and 2.36 nmol/g (95%CI: 2.09–2.65); respectively. After adjusting for confounders, blood mercury was associated with HRV parameters such as LF (β=0.21, P=0.0002), HF (β=0.15, P=0.004) and LF/HF (β=0.06, P=0.003). Similar associations were observed with hair mercury. In contrast, no significant association was observed between blood mercury or hair mercury and BP after adjusting for confounders. In conclusion, mercury exposure seems to affect HRV among Cree adults even after considering fish nutrients (n-3 fatty acids and selenium) and other contaminants (lead and polychlorinated biphenyls) that are also present in the traditional diet of this population.     

心肌梗死患者左室舒张功能评价方法的研究

探讨心肌梗死（ＭＩ）患者左室舒张功能的评价方法及临床应用。方法：采用脉冲多普勒超声心动 图技术检测５０例正常人和５０例ＭＩ患者的左房收缩时间间期（ＬＡＳＴＩ）。包括左房射血前期（ＡＰＥＰ）、校正心房射血 前期（ＡＰＥＰＣ）和左房射血期（ＡＥＴ）;肺静脉Ｓ峰、Ｄ峰、Ａ峰;二尖瓣血流Ｅ峰、Ａ峰及Ｅ／Ａ比值。ＭＩ组给予抗舒张 障碍治疗３周后再测量各项指标。结果：ＭＩ组的ＡＰＥＰ、ＡＰＥＰＣ缩短,ＡＥＴ延长;肺静脉Ｓ峰、Ａ峰增大,Ｄ峰减小; 二尖瓣Ｅ峰减小,Ａ峰增大（Ｐ＜０．０１）。ＭＩ组治疗３周后各项指标明显改善（Ｐ＜０．０１）。结论：综合多指标分析能 提高左室舒张功能评价的准确性。     

Bronchodilating Plasma Concentrations of Enprofylline and Theophylline have Minor Cardiovascular Effects in Man

Abstract: The cardiovascular effects with bronchodilating plasma concentration of theophylline (3.8–12.6 mg/l) and enprofylline (0.8–3.0 mg/l) were studied in six healthy male subjects by means of non-invasive procedures. With these plasma concentrations only minor effects were noted with regard to heart rate, blood pressure and systolic time intervals. However, both xanthines seem to have a vasodilating ability and a weak positive inotropic effect on the heart.     

Radionuclide Evaluation of Dual Chamber Pacing: Comparison Between Variable AV Intervals and Ventricular Pacing

We prospectively evaluated changes in left ventricular ejection fraction, end diastolic volume, and stroke volume via radionuclide multigated acquisition study, Comparison was made between ventricular pacing and dual chamber pacing with varying AV intervals. The volumes and changes in ejection fraction were determined at rest, at set increased pacing rates, and during physiological stress. AV sequential pacing shows overall improvement in cardiac function in the majority of patients regardless of left ventricular function. The shorter AV interval would be appropriate for the majority of patients who have an atrial tracking mechanism (adequate intrinsic sensed atrial activity followed by ventricular pacing) and who undergo significant physiological stress.     

Accelerometer-derived time intervals during various pacing modes in patients with biventricular pacemakers: comparison with normals

INTRODUCTION: Changes due to biventricular pacing have been documented by shortening of QRS duration and echocardiography. Compared to normal ventricular activation, the presence of left bundle branch block (LBBB) results in a significant change in cardiac cycle time intervals.Some of these have been used to quantify the underlying cardiac dyssynchrony, assess the effects of biventricular pacing, and guide programming of ventricular pacing devices. This study evaluates a simple noninvasive method using accelerometers attached to the skin to measure cardiac time intervals in biventricularly paced patients. METHODS: Ten patients with biventricular pacemakers previously implanted for congestive heart failure were paced in the AAI mode, then in atrioventricular (AV) sequential mode from the right and left ventricles followed by biventricular pacing. Simultaneous recordings were obtained by 2D, Doppler echocardiography as well as by accelerometers. Similar recordings were obtained from 10 gender, aged matched, normal controls during sinus rhythm. RESULTS: Compared to normals, heart failure patients paced in AAI mode had prolonged isovolumetric contraction time (IVCT), shorter ventricular ejection time (LVET), and prolonged isovolumetric relaxation (IVRT). With biventricular pacing the IVCT decreased, but the LVET and IVRT did not change significantly. There was excellent correlation between the echo and accelerometer-measured intervals. CONCLUSIONS: Shortening of the IVCT measured by an accelerometer is a consistent time interval change due to biventricular pacing that probably reflects more rapid acceleration of left ventricular ejection. The accelerometer may be useful to assess immediate efficacy of biventricular pacing during device implantation and optimize programmable time intervals such as AV and interventricular (VV) delays.