非典与中国的电子商务

探讨了非典对于中国电子商务的影响以及电子商务在此期间发挥出的作用、存在的不足，进而提出了关于如何促进中国电子商务进一步发展的思考和建议．     

Statistical considerations in clinical trial design with event-free survival as the primary efficacy endpoint

In late-phase confirmatory clinical trials in the oncology field, time-to-event (TTE) endpoints are commonly used as primary endpoints for establishing the efficacy of investigational therapies. Among these TTE endpoints, overall survival (OS) is always considered as the gold standard. However, OS data can take years to mature, and its use for measurement of efficacy can be confounded by the use of post-treatment rescue therapies or supportive care. Therefore, to accelerate the development process and better characterize the treatment effect of new investigational therapies, other TTE endpoints such as progression-free survival and event-free survival (EFS) are applied as primary efficacy endpoints in some confirmatory trials, either as a surrogate for OS or as a direct measure of clinical benefits. For evaluating novel treatments for acute myeloid leukemia, EFS has been gradually recognized as a direct measure of clinical benefits. However, the application of an EFS endpoint is still controversial mainly due to the debate surrounding definition of treatment failure (TF) events. In this article, we investigate the EFS endpoint with the most conservative definition for the timing of TF, which is Day 1 since randomization. Specifically, the corresponding non-proportional hazard pattern of the EFS endpoint is investigated with both analytical and numerical approaches.     

Evaluation of Inhaled Versus Deposited Dose Using the Exponential Dose‐Response Model for Inhalational Anthrax in Nonhuman Primate,Rabbit, and Guinea Pig

The application of the exponential model is extended by the inclusion of new nonhuman primate (NHP), rabbit, and guinea pig dose‐lethality data for inhalation anthrax. Because deposition is a critical step in the initiation of inhalation anthrax, inhaled doses may not provide the most accurate cross‐species comparison. For this reason, species‐specific deposition factors were derived to translate inhaled dose to deposited dose. Four NHP, three rabbit, and two guinea pig data sets were utilized. Results from species‐specific pooling analysis suggested all four NHP data sets could be pooled into a single NHP data set, which was also true for the rabbit and guinea pig data sets. The three species‐specific pooled data sets could not be combined into a single generic mammalian data set. For inhaled dose, NHPs were the most sensitive (relative lowest LD₅₀) species and rabbits the least. Improved inhaled LD₅₀s proposed for use in risk assessment are 50,600, 102,600, and 70,800 inhaled spores for NHP, rabbit, and guinea pig, respectively. Lung deposition factors were estimated for each species using published deposition data from Bacillus spore exposures, particle deposition studies, and computer modeling. Deposition was estimated at 22%, 9%, and 30% of the inhaled dose for NHP, rabbit, and guinea pig, respectively. When the inhaled dose was adjusted to reflect deposited dose, the rabbit animal model appears the most sensitive with the guinea pig the least sensitive species.     

Development of a Unit Risk Factor for 1,3-Butadiene Based on an Updated Carcinogenic Toxicity Assessment

The Texas Commission on Environmental Quality (TCEQ) has developed an inhalation unit risk factor (URF) for 1,3-butadiene based on leukemia mortality in an updated epidemiological study on styrene-butadiene rubber production workers conducted by researchers at the University of Alabama at Birmingham. Exposure estimates were updated and an exposure estimate validation study as well as dose-response modeling were conducted by these researchers. This information was not available to the U.S. Environmental Protection Agency when it prepared its health assessment of 1,3-butadiene in 2002. An extensive analysis conducted by TCEQ discusses dose-response modeling, estimating risk for the general population from occupational workers, estimating risk for potentially sensitive subpopulations, effect of occupational exposure estimation error, and use of mortality rates to predict incidence. The URF is 5.0 × 10⁻⁷ per μg/m³ or 1.1 × 10⁻⁶ per ppb and is based on a Cox regression dose-response model using restricted continuous data with age as a covariate, and a linear low-dose extrapolation default approach using the 95% lower confidence limit as the point of departure. Age-dependent adjustment factors were applied to account for possible increased susceptibility for early life exposure. The air concentration at 1 in 100,000 excess leukemia mortality, the no-significant-risk level, is 20 μg/m³ (9.1 ppb), which is slightly lower than the TCEQ chronic reference value of 33 μg/m³ (15 ppb) protective of ovarian atrophy. These values will be used to evaluate ambient air monitoring data so the general public is protected against adverse health effects from chronic exposure to 1,3-butadiene.     

The social construction of the meaning of acute stressors: a qualitative study of the personal accounts of police officers using a stress counselling service

The police profession is one in which acute stressors are encountered more frequently than in other occupations. Using the personal accounts of 35 police officers attending an in-house stress counselling clinic, the aim of the present study was to provide a qualitative examination of how the institutional context of policing influenced the ways in which acute stressors signified to individual police officers experiencing felt distress. Using the framework of Rational Emotive Behaviour Therapy as an analytical tool, it is argued that beliefs contributing to the experience of felt distress are related to the way in which policing as both an identity and an activity is constructed through the police organizational culture. Not only do these constructions influence the ways in which officers perceive themselves and their environments, but they also operate at the collective level to 'normalize' some emotional responses and to 'pathologize' others which, it is argued, could impact upon the outcomes of interventions such as stress counselling.     

老年急性白血病治疗方案的临床研究

目的研究治疗老年急性白血病的最佳策略,提高老年急性白血病患者完全缓解(CR)率,改善老年急性白血病患者的生活质量。方法回顾性分析35例老年急性白血病的临床表现,实验室检查特征及不同化疗方案的疗效。结果:联合化疗17例,CR率47%(8/17),其中急性非淋巴细胞性白血病(ANLL)9例,CR率44.4%(4/9);急性淋巴细胞性白血病(ALL)8例,CR率50%(4/8)。小剂量阿糖胞苷(Ara-C)或三尖杉脂碱(H)化疗9例,CR率22.2%(2/9)。全反式维甲酸(ATRA)治疗3例,1例安全缓解。姑息治疗6例。结论临床上老年急性白血病普遍对化疗反应差,CR率低。对老年急性白血病应选择积极、合理、个体化的治疗方案,有利于提高老年急性白血病的疗效,改善老年急性白血病患者的生活质量。     

LDH在中老年恶性血液病血清中的变化及临床意义

目的探讨中老年恶性血液病患者血清中乳酸脱氢酶(LDH)的变化及其临床意义,为临床应用提供理论依据。方法将恶性血液病分为骨髓增生异常综合征(MDS)组、白血病组,同时设立再障组、正常组以示对照,应用国际血液学标准化委员会推荐的酶法对恶性血液病(MDS、急慢性白血病)、再生障碍性贫血(再障,AA)及正常人血清LDH进行检测并进行比较。结果MDS组、白血病组与正常组、再障组相比较血清LDH水平有明显差异,MDS组与白血病组相比较血清LDH水平有明显差异,正常组与再障组相比较血清LDH水平无明显差异。结论血清LDH水平可作为中老年恶性血液病与再障鉴别诊断及恶性血液病间鉴别诊断的观察指标。     

Acute Exposure to Extremely Hazardous Substances: An Analysis of Environmental Equity

Although environmental equity research has focused primarily on chronic pollution sources, recent advances in environmental modeling and geographic information systems (GIS) provide a foundation for developing measures that can be used to evaluate differential exposure to acute pollution events. This article describes a methodology that uses facility-specific information to develop a risk surface representing the spatial distribution of accidental exposure to hazardous substances in a study area. Environmental pollution models recommended by the U.S. Environmental Protection Agency were used in conjunction with GIS software to achieve this objective. The methodology was implemented in a large metropolitan region (Hillsborough County, Florida) to examine disproportionate exposure to worst-case releases of extremely hazardous substances. The environmental inequity hypothesis was investigated by directly comparing the distribution of potential exposures within each racial (non-White versus White) and income (below poverty versus above poverty) subgroup. The results indicate that a significantly large proportion of both non-White and impoverished individuals resided in areas potentially exposed to multiple accidental releases.     

Formative research methods to understand patient and provider responses to heart attack symptoms

Formative research is often required for program planning, and for reducing uncertainty about generalizability of program effects. This article describes and justifies methods of formative research conducted for the REACT study (Rapid Early Action for Coronary Treatment), a multi-center collaborative randomized community trial aimed at reducing patient delay in seeking care for acute myocardial infarction (AMI). Formative research cast light on patient and community members’ decision-making process in seeking help for AMI, as well as barriers and facilitators of this process. Investigators at all five REACT Field Centers participated in the formative research. The process consisted of: (1) developing a common theoretical framework for the study intervention; (2) conducting a literature review and qualitative research to identify and address gaps in knowledge; and (3) developing a common protocol for the REACT study that accommodated the diversity of the target communities in terms of services, resources, history, and ethnicity. Analysis employed triangulation, defined as an explicit search for heterogeneous data sources to reduce uncertainty about forces at work and opportunities for intervention across settings and populations. Because the collection and interpretation of data went in stages, staff of several REACT Field Centers had independent input to the overall synthesis, then shared and revised the results. Advantages and limitations of this approach are discussed.     

急性脑梗死后血糖升高的临床意义

目的探讨急性脑梗死后血糖水平与其预测的关系.方法经CT或MRI确诊的急性脑梗死患者发病48h内空腹检测血糖,根据血糖水平分为血糖正常、血糖升高两组.血糖升高组患者于急性期同时测定糖基血红蛋白,分析两组血糖水平与脑梗死患者神经功能评分、临床疗效及死亡率的关系.结果非糖尿病急性脑梗死患者血糖升高大部分发生于卒中后,其血糖升高多见于皮质梗死即累及主干支大灶性梗死,其神经功能缺损和临床疗效明显差于血糖正常组,而且死亡率高.结论急性脑梗死后血糖升高可加重脑梗死损害,严格检测和控制血糖有助于脑梗死的预测.