An Exposure‐Response Threshold for Lung Diseases and Lung Cancer Caused by Crystalline Silica

Whether crystalline silica (CS) exposure increases risk of lung cancer in humans without silicosis, and, if so, whether the exposure‐response relation has a threshold, have been much debated. Epidemiological evidence is ambiguous and conflicting. Experimental data show that high levels of CS cause lung cancer in rats, although not in other species, including mice, guinea pigs, or hamsters; but the relevance of such animal data to humans has been uncertain. This article applies recent insights into the toxicology of lung diseases caused by poorly soluble particles (PSPs), and by CS in particular, to model the exposure‐response relation between CS and risk of lung pathologies such as chronic inflammation, silicosis, fibrosis, and lung cancer. An inflammatory mode of action is described, having substantial empirical support, in which exposure increases alveolar macrophages and neutrophils in the alveolar epithelium, leading to increased reactive oxygen species (ROS) and nitrogen species (RNS), pro‐inflammatory mediators such as TNF‐alpha, and eventual damage to lung tissue and epithelial hyperplasia, resulting in fibrosis and increased lung cancer risk among silicotics. This mode of action involves several positive feedback loops. Exposures that increase the gain factors around such loops can create a disease state with elevated levels of ROS, TNF‐alpha, TGF‐beta, alveolar macrophages, and neutrophils. This mechanism implies a “tipping point” threshold for the exposure‐response relation. Applying this new model to epidemiological data, we conclude that current permissible exposure levels, on the order of 0.1 mg/m³, are probably below the threshold for triggering lung diseases in humans.     

揭开朝鲜神话迷宫的金钥匙——简评《朝鲜神话研究》

《朝鲜神话研究》一书系阐述东亚国别神话的学术专著之一 ,运用中西神话学新理论与方法论 ,较系统地梳理出朝鲜神话的流变史、叙事体系与结构及民族文化深层意蕴 ,自成一个理论体系 ,在前人研究成果的基础上有所突破。     

Korean Twins Reared Apart: Genetic and Cultural Influences on Behavior and Health

Monozygotic twins reared in different countries are rare. Data from several available cases have been combined in group findings, masking cultural effects on behavior. The present study compared behavioral and health-related findings for unusual monozygotic female twins raised apart in South Korea and the United States. The 37-year-old twins were exceptional in being reared under dramatically different circumstances with limited telephone and Internet contact. Primary outcome measures included life history events, physical and health-related characteristics, and diverse behavioral traits. Striking similarities and differences were noted. Findings are discussed with reference to genetic and cultural influences on health and behavior.     

Effects of Disease Type and Latency on the Value of Mortality Risk

We evaluate the effects of disease type and latency on willingness to pay (WTP) to reduce environmental risks of chronic, degenerative disease. Using contingent-valuation data collected from approximately 1,200 respondents in Taiwan, we find that WTP declines with latency between exposure to environmental contaminants and manifestation of any resulting disease, at a 1.5 percent annual rate for a 20 year latency period. WTP to reduce the risk of cancer is estimated to be about one-third larger than WTP to reduce risk of a similar chronic, degenerative disease. The value of risk reduction also depends on the affected organ, environmental pathway, or payment mechanism: estimated WTP to reduce the risk of lung disease due to industrial air pollution is twice as large as WTP to reduce the risk of liver disease due to contaminated drinking water.     

Social Work with the Osteoporotic Woman

A chronic, progressive, and potentially debilitating condition, osteoporosis has a multitude of currently untapped implications for effective social work practice. A working knowledge of the medical framework of the disease process itself is a prerequisite to informed practice. This article presents such information, along with the psychological and social components, in order to provide the social worker with the comprehensive biopsyehosaial knowledge base necessary for effective practice with the osteoporotic woman and her family.     

Inference for general parametric functions in box‐Cox‐type transformation models

The authors propose a simple but general method of inference for a parametric function of the Box‐Cox‐type transformation model. Their approach is built upon the classical normal theory but takes parameter estimation into account. It quickly leads to test statistics and confidence intervals for a linear combination of scaled or unsealed regression coefficients, as well as for the survivor function and marginal effects on the median or other quantité functions of an original response. The authors show through simulations that the finite‐sample performance of their method is often superior to the delta method, and that their approach is robust to mild departures from normality of error distributions. They illustrate their approach with a numerical example.     

Intergenerational income mobility and inequality in South Korea

Using data from the Korean Labor and Income Panel Study (KLIPS), recent trends in intergenerational income mobility were explored, examining the relationship between income mobility and income inequality in South Korea. The study found that the intergenerational elasticity of income is about 0.2 and there is no clear‐cut trend in intergenerational income mobility. In addition, this study showed that there is no systematic relation between rising income inequality and intergenerational income mobility in contemporary Korea. Overall, the results indicate that intergenerational income mobility is irresponsive to the income inequality the respondents experienced growing up. It is assumed that education and welfare transfer programs might offset the consequences of income inequality by leading to upward mobility for children from low‐income households.     

A stochastically curtailed two-arm randomised phase II trial design for binary outcomes

Randomised controlled trials are considered the gold standard in trial design. However, phase II oncology trials with a binary outcome are often single-arm. Although a number of reasons exist for choosing a single-arm trial, the primary reason is that single-arm designs require fewer participants than their randomised equivalents. Therefore, the development of novel methodology that makes randomised designs more efficient is of value to the trials community. This article introduces a randomised two-arm binary outcome trial design that includes stochastic curtailment (SC), allowing for the possibility of stopping a trial before the final conclusions are known with certainty. In addition to SC, the proposed design involves the use of a randomised block design, which allows investigators to control the number of interim analyses. This approach is compared with existing designs that also use early stopping, through the use of a loss function comprised of a weighted sum of design characteristics. Comparisons are also made using an example from a real trial. The comparisons show that for many possible loss functions, the proposed design is superior to existing designs. Further, the proposed design may be more practical, by allowing a flexible number of interim analyses. One existing design produces superior design realisations when the anticipated response rate is low. However, when using this design, the probability of rejecting the null hypothesis is sensitive to misspecification of the null response rate. Therefore, when considering randomised designs in phase II, we recommend the proposed approach be preferred over other sequential designs.     

Cigarette Smoking Among Korean International College Students in the United States

Abstract

Objective and Participants: This study explored (1) the prevalence of cigarette smoking among South Korean international college students in the United States, (2) differences in smoking between on- and off-campus living arrangements, and (3) predictors of an increase in smoking over time in the United States Methods: An online survey was completed by 1,201 students at 52 4-year US universities (34% response rate). Results: The overall smoking prevalence was 43.5%. The smoking rate (29.0%) of female students was higher than that (4%) of female college students in South Korea. Sex, living place, living situation, length of stay as a student in the United States, home smoking rules, campus-wide tobacco-free policies, and levels of acculturative stress, anxiety, and depression were significantly associated with an increase in smoking (p < .05). Conclusions: Given the high smoking prevalence among the South Korean students on US college campuses, targeted prevention efforts for these students may be warranted.