Biomedical subjects
Publications and source records attributed to J M Samet.
Neoplastic development is a multistage process that includes multiple genetic changes. In this article the authors review studies on molecular epidemiology of tobacco. Current concepts of the multistage carcinogenic model are reviewed, as are their use in observational studies. Finally, benzo[a]pyrene are analyzed as an example.
Phospholipase A2 (PLA2) is a pivotal enzyme involved in the synthesis of the potent lipid inflammatory mediators platelet activating factor (PAF) and the eicosanoids. This study characterizes a PLA2 recovered in the bronchoalveolar lavage fluid (BALF) of healthy adult human subjects. Human BALF PLA2 exhibited characteristics of secretory PLA2s that include an activity that is acid stable, sensitive to reducing agents, and optimally requires millimolar calcium. BALF PLA2 showed marked selectivity for phosphatidylcholine containing arachidonic acid (AA) over linoleic or palmitic acids. Size exclusion chromatography showed the BALF PLA2 protein to be approximately 14 kDa in mass, consistent with it being a secretory form of PLA2. The biological significance of BALF PLA2 was tested by applying BALF concentrates to cultures of the human bronchial epithelial cell line BEAS 2B. Cultures of BEAS 2B cells treated with BALF concentrates released increased amounts of AA and produced higher levels of PAF. These data show that the lining fluid of the human respiratory tract normally contains a secretory PLA2, which may be involved in the formation of lipid inflammatory mediators in normal and pathophysiologic states in the lung.
Residential and occupational exposure to radon is the second leading cause of lung cancer after cigarette smoking. As many as eight million homes in the US have elevated radon levels according to Environmental Protection Agency estimates. High exposure levels in homes are largely a result of radon-contaminated gas rising from the soil. This makes it an unusual indoor air pollutant in that it has a natural source. This study examines the synergism between smoking and radon, what levels are considered safe, and what to do to safeguard against overexposure to radon.
PURPOSE: To estimate the independent effect of cigarette smoking on respiratory tract symptoms and health status indicators among high school seniors. DESIGN: Consolidated data sets from one-time cross-sectional survey designs. SETTING: High schools in the United States, 1982-1989. SAMPLE: A total of 26,504 high school seniors, with an 83% response rate. MEASURES: Odds ratios for respiratory tract symptoms and health status indicators for cigarette smokers compared with nonsmokers, while controlling for sex, socioeconomic status, and use of other drugs. RESULTS: High school seniors who were regular cigarette smokers and who began smoking by grade nine were significantly more likely than never smokers to report shortness of breath when not exercising (adjusted odds ratio [OR] = 2.7), coughing spells (OR = 2.1), productive cough (OR = 2.4), and wheezing or gasping (OR = 2.6). These smokers were also more likely to have seen a doctor or other health professional for an emotional or psychologic complaint (OR = 3.0) and to rate their overall health as poorer than average (OR = 2.4). We found strong dose-response relationships for most outcome measures. CONCLUSIONS: Cigarette smoking among high school seniors is associated with respiratory tract symptoms and poorer overall physical health and may be a marker for underlying mental health problems. Smoking prevention activities directed at adolescents should include information on the early adverse health consequences of cigarette smoking.
Surveys of cigarette smoking among Hispanics in the Southwest have shown a pattern of smoking distinct from that of non-Hispanic whites, but determinants of smoking by Hispanics remain inadequately characterized. We have assessed household income, education, and language preference as predictors of cigarette smoking in 1072 Hispanic adults residing in a community in New Mexico. Cigarette smoking status (never, former, or current smoker) varied strongly with educational attainment, showing the anticipated gradient of increasing smoking as level of education declined. In contrast, cigarette smoking status did not vary in a consistent pattern with reported language preference. A composite measure of socioeconomic status, combining education and household income, predicted continued smoking among ever smokers, whereas language preference had no effect. In males, the age at which subjects started to smoke increased significantly with increasing education; a similar trend in females did not reach statistical significance. Determinants of numbers of cigarettes smoked daily were not identified. The findings suggest that, as in other U.S. populations, Hispanics in the Southwest with lower education and less income should be targeted for smoking prevention and cessation.
Excess lung cancer has been demonstrated in many groups of underground miners exposed to radon, including uranium miners and those mining other substances in radon-contaminated mines. In the United States, most underground uranium mines had shut down by the late 1980s, but occupational exposure to radon progeny remains a concern for many other types of underground miners and other underground workers. Worldwide, uranium mining continues, with documented production in Canada, South Africa and other African countries, and Australia. Thus, radon in underground mines remains a significant occupational hazard as the end of the twentieth century approaches.
The role of combustion products in building-associated illness is addressed. The authors emphasize carbon monoxide, nitrogen dioxide, wood smoke, and vehicle exhaust. The limited literature available suggests that combustion products, other than tobacco smoke, may be a relatively uncommon cause of building-related problems.
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