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J Samet

Publications and source records attributed to J Samet.

At least 19 recordsLinked to original sources
PubMed2006

A case-crossover study of fine particulate matter air pollution and onset of congestive heart failure symptom exacerbation leading to hospitalization.

Persons with congestive heart failure may be susceptible to ambient air pollution. The authors evaluated the association between exposure to particulate matter with an aerodynamic diameter of <2.5 microm (PM2.5) and onset of symptom exacerbation leading to hospital admission in Baltimore, Maryland. They used a case-crossover design for 135 case events occurring among 125 persons with prevalent congestive heart failure who were admitted to a single hospital through the emergency department during 2002. The case period was assigned using three index times: 8-hour and 24-hour periods of symptom onset and date of hospital admission. Controlling for weather, the authors detected a modest relative increase in risk for cases defined by 8-hour symptom onset for an interquartile-range increase in PM2.5 at a 2-day lag (odds ratio=1.09, 95% confidence interval: 0.91, 1.30). A corresponding increase in risk was not observed when admission date was used to define the case period. A series of simulations based on study data indicated that the study had adequate statistical power to detect odds ratios of 1.2 or higher. Although overall findings were not statistically significant, the identification of case events defined by an 8-hour onset period may be more relevant than either a 24-hour onset period or the admission date for estimating harmful effects of air pollutant exposure on cardiovascular health.

Aged↗
PubMed2006

Building capacity for tobacco control research and policy.

The Fogarty International Center (FIC) initiative, "International Tobacco and Health Research Capacity Building Program" represents an important step in US government funding for global tobacco control. Low- and middle-income countries of the world face a rising threat to public health from the rapidly escalating epidemic of tobacco use. Many are now parties to the Framework Convention on Tobacco Control (FCTC) and capacity development to meet FCTC provisions. One initial grant provided through the FIC was to the Institute for Global Tobacco Control (IGTC) at the Johns Hopkins Bloomberg School of Public Health (JHSPH) to support capacity building and research programmes in China, Brazil, and Mexico. The initiative's capacity building effort focused on: (1) building the evidence base for tobacco control, (2) expanding the infrastructure of each country to deliver tobacco control, and (3) developing the next generation of leaders as well as encouraging networking throughout the country and with neighbouring countries. This paper describes the approach taken and the research foci, as well some of the main outcomes and some identified challenges posed by the effort. Individual research papers are in progress to provide more in-depth reporting of study results.

Brazil↗
PubMed2004

Achieving the Framework Convention on Tobacco Control's potential by investing in national capacity.

May 2003 marked a critical achievement in efforts to stem the global tobacco epidemic, as the member states of the World Health Organization unanimously endorsed the Framework Convention on Tobacco Control (FCTC). However, the adoption of the FCTC signifies only the end of the beginning of effective global action to control tobacco. Over the next several years the utility of the FCTC process and the treaty itself will be tested as individual countries seek to ratify and implement the treaty's obligations. Significant barriers to the treaty's long term success exist in many countries. It is crucial that the international tobacco control community now refocuses its efforts on national capacity building and ensures that individual countries have the knowledge, tools, data, people, and organisations needed to implement the convention and develop sustained tobacco control programmes. This paper provides a model of national tobacco control capacity and offers a prioritised agenda for action.

Cost of Illness↗
PubMed2001

Association of alcohol consumption with HIV sex- and drug-risk behaviors among drug users.

The relationship between alcohol use and HIV transmission is well recognized but not fully understood. In particular, the role of alcohol abuse as a mediator of HIV risk behavior among drug users is not well documented. We hypothesized that alcohol use in drug users will result in greater HIV risk-taking behavior. Participants were 354 drug users, of whom 105 were recent injection drug users. Multiple regression models were used to characterize whether measures of sexual and injection drug use HIV risk behavior were related to alcohol consumption, controlling for other potentially associated factors. We found that sexual HIV risk-taking behavior is associated with increased alcohol consumption among women (p = 0.02), with women having more risky sexual behavior than males. However, contrary to our hypothesis, there was no significant association of alcohol consumption with risky injection drug behavior. Addressing alcohol problems among drug users, particularly women, may be an important opportunity to reduce HIV sexual risk behavior among this high-risk population.

Adult↗
PubMed2001

Family history and risk of breast cancer in hispanic and non-hispanic women: the New Mexico Women's Health Study.

OBJECTIVES: Many epidemiologic studies have demonstrated that an increased risk of breast cancer is associated with positive family history of this disease. Little information had been available on the relationship of breast cancer risk with family history in Hispanic women. To investigate the association of family history of breast cancer on the risk of breast cancer, we examined the data from the New Mexico Women's Health Study (NMWHS), a statewide case-control study. METHODS: In this study 712 women (332 Hispanics and 380 non-Hispanic whites) with breast cancer and 844 controls (388 Hispanics and 456 non-Hispanic whites) were included. Conditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (95% CI). adjusted for sociodemographic, medical, and reproductive factors. RESULTS: We found an increased risk in women with a history of breast cancer in one or more first-degree or second-degree relatives (OR= 1.5, 95% CI 1.2-1.9), first-degree relatives (OR= 1.3, 95% CI 1.0-1.8) and second-degree relatives (OR = 1.6, 95% CI 1.2-2.2). Hispanic women had higher risk estimates for a positive family history (OR= 1.7, 95% CI 1.1-2.5) than non-Hispanic white women (OR= 1.4, 95% CI 1.0-2.0); however, the differences were not statistically significant. In both ethnic groups a higher risk was observed in premenopausal women compared with postmenopausal women and women diagnosed with breast cancer before age 50 years compared with older women. CONCLUSIONS: The results indicate that Hispanic women with a family history of breast cancer are at increased risk of breast cancer.

Adult↗
PubMed2001

Pfiesteria: review of the science and identification of research gaps. Report for the National Center for Environmental Health, Centers for Disease Control and Prevention.

In connection with the CDC National Conference on Pfiesteria, a multidisciplinary panel evaluated Pfiesteria-related research. The panel set out what was known and what was not known about adverse effects of the organism on estuarine ecology, fish, and human health; assessed the methods used in Pfiesteria research; and offered suggestions to address data gaps. The panel's expertise covered dinoflagellate ecology; fish pathology and toxicology; laboratory measurement of toxins, epidemiology, and neurology. The panel evaluated peer-reviewed and non-peer-reviewed literature available through June 2000 in a systematic conceptual framework that moved from the source of exposure, through exposure research and dose, to human health effects. Substantial uncertainties remain throughout the conceptual framework the panel used to guide its evaluation. Firm evidence demonstrates that Pfiesteria is toxic to fish, but the specific toxin has not been isolated or characterized. Laboratory and field evidence indicate that the organism has a complex life cycle. The consequences of human exposure to Pfiesteria toxin and the magnitude of the human health problem remain obscure. The patchwork of approaches used in clinical evaluation and surrogate measures of exposure to the toxin are major limitations of this work. To protect public health, the panel suggests that priority be given research that will provide better insight into the effects of Pfiesteria on human health. Key gaps include the identity and mechanism of action of the toxin(s), the incomplete description of effects of exposure in invertebrates, fish, and humans, and the nature and extent of exposures that place people at risk.

Animals↗
PubMed2000

Physical and sexual abuse in women infected with the human immunodeficiency virus: increased illness and health care utilization.

BACKGROUND: A history of physical or sexual abuse is associated with increased health care utilization and possibly an increase in illness based largely on self-reported data. OBJECTIVE: To examine whether victimization experience is associated with increases in documented medical disease and health care utilization among women infected with the human immunodeficiency virus (HIV). METHODS: We interviewed and reviewed medical record data of 50 women seeking initial primary care for HIV infection at 2 urban hospitals. Women with and without a history of physical and sexual abuse were compared. Using multiple regression analysis, 2 periods were examined: entire life before study entry and the subsequent 2 years. The characteristics examined included episodic disease, chronic disease, sexually transmitted disease, chronic pain syndrome, opportunistic infections, obstetrical history, and number of injuries, surgical procedures, hospitalizations, ambulatory care visits, and emergency department visits. RESULTS: Evidence of physical or sexual abuse was found in 34 (68%) of the 50 women, of whom 16 (32%) did not disclose during the interview that they were abused. At entry, the rates of episodic disease, chronic pain syndrome, and sexually transmitted disease were greater among those women with histories of abuse. At 2 years, episodic disease, chronic disease, injuries, emergency department visits, and hospitalizations were all more likely in abused women. CONCLUSION: Physical and sexual abuse are common and associated with increased medical disease and health care utilization among HIV-infected women.

Adult↗
PubMed2000

Women and tobacco: moving from policy to action.

A gender perspective contributes to a better understanding of the epidemiological trends, social marketing strategies, economic policies, and international actions relating to women and the tobacco epidemic. Evidence is provided in this article for the negative impact of tobacco use by women and of passive smoking on the health of women and children. Use of tobacco by women is increasing and this is related to the tobacco industry's aggressive advertising, sponsorship and promotion strategies. Policy directions are proposed in this article. At all levels, a multi-pronged strategy--including changes in legislation and fiscal policies, improvements in gender-sensitive health services, and cessation programmes--should be considered. Much more gender-specific research on tobacco use is needed, particularly in developing countries. Women's empowerment and leadership should be at the centre of all tobacco control efforts and are essential for the success of national programmes and the recently introduced Framework Convention on Tobacco Control.

Adolescent↗
PubMed1999

Environmental tobacco smoke: exposure assessment in the workplace

The Johns Hopkins University School of Hygiene and Public convened a multidisciplinary workshop 12-13 September 1997 to assess current understanding of environmental tobacco smoke (ETS) exposure in the workplace. Invited participants represented areas of expertise in building systems, measurement of ETS, biomarkers of ETS exposure, time-activity patterns, and exposure models. Workshop participants were asked to conduct reviews in their specific areas of expertise relevant to the following general charge: to address key issues related to ETS exposure in the workplace to prepare the groundwork for risk assessment of the hazard that ETS poses to workers. Discussions focused on the extent of the data available on exposures of workers to ETS and approaches used to estimate exposures to ETS in the workplace. The monograph based on this workshop includes individual contributions that provide in-depth coverage of the specific areas and a summary of the discussion that describes an approach to estimating exposures of the nation's workers to ETS as well as research recommendations.

Journal Article↗
PubMed1999

Harvesting-resistant estimates of air pollution effects on mortality.

A number of studies have recently shown an association between particle concentrations in outdoor air and daily mortality counts in urban locations. In the public health interpretation of this evidence, a key issue is whether the increased mortality associated with higher pollution levels is restricted to very frail persons for whom life expectancy is short in the absence of pollution. This possibility has been termed the "harvesting hypothesis." We present an approach to estimating the association between pollution and mortality from times series data that is resistant to short-term harvesting. The method is based in the concept that harvesting alone creates associations only at shorter time scales. We use frequency domain log-linear regression to decompose the information about the pollution-mortality association into distinct time scales, and we then create harvesting-resistant estimates by excluding the short-term information that is affected by harvesting. We illustrate the methods with total suspended particles and mortality counts from Philadelphia for 1974-1988. The total suspended particles-mortality association in Philadelphia is inconsistent with the harvesting-only hypothesis, and the harvesting-resistant estimates of the total suspended particles relative risk are actually larger-not smaller-than the ordinary estimates.

Air Pollution↗
PubMed1998

Does weather confound or modify the association of particulate air pollution with mortality? An analysis of the Philadelphia data, 1973-1980.

Because weather has the potential to confound or modify the pollution-mortality relationship, researchers have developed several approaches for controlling it in estimating the independent effect of air pollution on mortality. This report considers the consequences of using alternative approaches to controlling for weather and explores modification of air pollution effects by weather, as weather patterns could plausibly alter air pollution's effect on health. We analyzed 1973-1980 total mortality data for Philadelphia using four weather models and compared estimates of the effects of TSP and SO2 on mortality using a Poisson regression model. Two synoptic categories developed by Kalkstein were selected--the Temporal Synoptic Index (TSI) and the Spatial Synoptic Classification (SSC)--and compared with (1) descriptive models developed by Schwartz and Dockery (S-D); and (2) LOESS, a non-parametric function of the previous day's temperature and dew point. We considered model fit using Akaike's Information Criterion (AIC) and changes in the estimated effects of TSP and SO2. In the full-year analysis, S-D is better than LOESS at predicting mortality, and S-D and LOESS are better than TSI, as measured by AIC. When TSP or SO2 was fit alone, the results were qualitatively similar, regardless of how weather was controlled; when TSP and SO2 were fit simultaneously, the S-D and LOESS models give qualitatively different results than TSI, which attributes more of the pollution effect to SO2 than to TSP. Model fit is substantially poorer with TSI. This pattern was repeated in analyses of summer and winter months, which included SSC. In summary, using synoptic weather categories in regression models does not meaningfully change the association between mortality and air pollution indexes. We also found little evidence that weather conditions modified the effect of pollution, regardless of the approach used to represent weather.

Air Pollution↗
PubMed1998

Air pollution particles induce IL-6 gene expression in human airway epithelial cells via NF-kappaB activation.

Fine particles in the air have been associated with increased mortality and morbidity. Particulate air pollution is a complex mixture which varies by region and includes a number of components including residual oil fly ash (ROFA), a byproduct of power plant and industry fuel-oil combustion. Human airway epithelial cells exposed to ROFA release inflammatory cytokines including interleukin (IL)-6, IL-8, and tumor necrosis factor. Expression of these genes is dependent upon pretranscriptional binding of cis regulatory elements, including nuclear factor kappaB (NF-kappaB). To investigate the role of NF-kappaB in the particulate-induced IL-6 response, we exposed human airway epithelial cells (BEAS-2B) to ROFA in vitro. ROFA stimulated a time- and dose-dependent increase in IL-6 messenger RNA (mRNA), which was preceded by the activation of nuclear proteins binding to the NF-kappaB sequence motif in the IL-6 promoter. Transient transfection of BEAS-2B cells with the 5' promoter region of the IL-6 gene linked to a luciferase reporter gene confirmed that NF-kappaB binding is necessary for the transcription of IL-6 mRNA. The IL-6 response was inhibited by the metal chelator deferoxamine and the free radical scavenger N-acetyl-L-cysteine, suggesting that the activation of NF-kappaB may be mediated through reactive oxygen intermediates generated by transition metals found in ROFA. Activation of NF-kappaB may therefore be a critical first step in the inflammatory cascade following exposure to particles generated by oil combustion.

Acetylcysteine↗
PubMed1998

Copper-dependent inflammation and nuclear factor-kappaB activation by particulate air pollution.

Particulate air pollution causes increased cardiopulmonary morbidity and mortality, but the chemical determinants responsible for its biologic effects are not understood. We studied the effect of total suspended particulates collected in Provo, Utah, an area where an increase in respiratory symptoms in relation to levels of particulate pollution has been well documented. Provo particulates caused cytokine-induced neutrophil chemoattractant-dependent inflammation of rat lungs. Provo particulates stimulated interleukin-6 (IL-6) and IL-8 production, increased IL-8 messenger RNA (mRNA) and enhanced expression of intercellular adhesion molecule-1 (ICAM-1) in cultured BEAS-2B cells, and stimulated IL-8 secretion in primary cultures of human bronchial epithelium. Cytokine secretion was preceded by activation of the transcription factor nuclear factor-kappaB (NF-kappaB) and was reduced by treatment of cultures with superoxide dismutase, deferoxamine, or N-acetylcysteine. These biologic effects were replicated by culturing BEAS cells with quantities of Cu2+ found in Provo extract. IL-8 secretion by BEAS cells could be modified by addition of normal constituents of airway lining fluid to the culture medium. Mucin significantly reduced IL-8 secretion, and ceruloplasmin significantly increased IL-8 secretion and activation of NF-kappaB. These findings suggest that copper ions may cause some of the biologic effects of inhaled particulate air pollution in the Provo region of the United States, and may provide an explanation for the sensitivity of asthmatic individuals to Provo particulates that has been observed in epidemiologic studies.

Air Pollution↗
PubMed1993

The thymidylate synthase inhibitor, ICI D1694, overcomes translational detainment of the enzyme.

We have investigated the mechanism of inactivation of thymidylate synthase (TS) by ICI D1694 (a folate-based quinazoline) in normal versus tumor-derived human mammary epithelial cells. ICI D1694 is a very potent cytotoxic agent against these cells with IC50 values of 1-2 nM. Its growth inhibitory activity was completely reversed by the addition of thymidine, confirming that TS is its sole target in these cells. Remarkably, TS protein levels rose by 10-40-fold following treatment with ICI D1694, depending on cell type, while TS mRNA levels remained constant. The mechanism appears to be a release of "detainment" of TS translation, since addition of cycloheximide, a translational inhibitor, blocked the TS protein levels from rising. But coadministration of 5,6-dichlorobenzimidazole, a transcriptional inhibitor, did not overcome protein accumulation, nor did thymidine which overcomes growth inhibition by ICI D1694. 5,10-Methylenetetrahydrofolate (via folinic acid), however, did block the effects of ICI D1694, showing that the drug has its effect upon both detainment and enzyme inhibition by binding to the folate substrate site of TS. In addition, in the presence of ICI D1694, TS protein was no longer cell cycle-regulated as evident by its constitutive expression in synchronized cells. This accumulation and constitutive expression of TS induced by D1694 should increase drug resistance under a clinical setting. We suggest that an ideal inhibitor of TS would target the TS allosteric site that binds to TS mRNA, responsible for specific translation of the protein, thereby complimenting inactivation of the enzyme.

Cell Cycle↗
PubMed1992

Dyspnea, anxiety, and depression in chronic respiratory impairment.

In order to examine the relationship of dyspnea to anxiety and depression, the authors rated dyspnea using several methods in 50 patients with chronic respiratory impairment. Anxiety and depression were measured by the Symptom Checklist-90 and the Symptom Questionnaire. Results varied with the method of assessing dyspnea. Physician-rated dyspnea was significantly associated with patients' self-ratings of breathlessness as well as with pulmonary function tests, but not with any of the self-rating scales of emotions. Self-rated breathlessness was significantly associated with self-rated depression. In multiple regression analyses, depression was predictive of breathlessness. When the sample was limited to patients with chronic obstructive pulmonary disease, the results remained the same. The patients were significantly more depressed and anxious than matched family practice patients. In the study of the complex relationship of dyspnea to physical and emotional factors, it is desirable to use more than one measure of dyspnea because the results depend in part on the method of assessment.

Adult↗