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Biomedical subjects

J M Samet

Publications and source records attributed to J M Samet.

At least 145 records · Page 8Linked to original sources
PubMed1993

Prediction of lung function in Hispanics using local ethnic-specific and external non-ethnic-specific prediction equations.

We compared locally derived prediction equations for the FVC and FEV1 in Hispanics with external prediction equations derived from non-Hispanic whites. Algebraic subtraction of the external non-Hispanic equations from the New Mexico Hispanic equations showed that the differences would vary with age and height. The study population included 442 patients with Hispanic surnames between the ages of 25 and 80 yr evaluated at the University of New Mexico Hospital pulmonary function laboratory. We calculated percent predicted values for FVC and FEV1 using spirometric prediction equations from a New Mexico Hispanic population and from non-Hispanic white populations in Salt Lake City, Tucson, and six other U.S. cities. We employed either 80% of predicted or the lower fifth percentile as the criterion for separating normal from abnormal values. We found that the concordance of the classifications by the external and internal equations varied among the external equations and with the criterion used for abnormality. The classification of the FVC and FEV1 as normal or abnormal was influenced by the regression equation in about 5 to 10% of the subjects. Subjects with discordant classifications were not clearly predicted by age or height, although they tended to be at the extremes of the age and height distributions. This study shows that classification of lung function by locally derived ethnic-group-specific prediction equations may lead to a differing clinical categorization for some persons in comparison with external non-ethnic-group-specific equations.

Adult↗
PubMed1993

Cigarette yields of tar and nicotine and markers of exposure to tobacco smoke.

Although cigarette yields of tar and nicotine have been declining since the early 1970s, little information is available for the general population on the consequences of their use on exposure to tobacco combustion products. In a population-based sample of 298 smokers, the majority of whom were Hispanic, we examined the relationships between yields of cigarettes currently smoked and levels of salivary cotinine and end-expired carbon monoxide. Spearman correlation coefficients between the current number of cigarettes smoked and cotinine (r = 0.52) or carbon monoxide (r = 0.51) were higher than correlations between the Federal Trade Commission (FTC) nicotine data and these same markers, 0.12 and 0.05, respectively. Correlations between FTC tar and carbon monoxide yields and the biologic markers were similarly weak. In multiple linear regression models, the current number of cigarettes smoked was the most important predictor of cotinine and carbon monoxide levels (p < 0.0001). The addition of FTC tar, nicotine, or carbon monoxide to the models explained little of the variability in cotinine or carbon monoxide levels. Because FTC yields of tar and nicotine are poor predictors of exposure to tobacco combustion products, subjects' reports of cigarette brand should not be used as a primary marker of exposure in epidemiologic investigations. Furthermore, smokers need to be advised about the limitations of cigarette yield information for predicting the potential for adverse health effects of smoking.

Adult↗
PubMed1993

Comparability of parent reports of respiratory illnesses with clinical diagnoses in infants.

In a cohort study of respiratory illnesses from birth through age 18 months, the investigators assessed the occurrence of illness by telephone reports of respiratory symptoms. To assess the comparability of illness events based on symptom reports with usual clinical modalities, a nurse practitioner examined children during illnesses, and office and clinic records of outpatient visits were reviewed. Respiratory illnesses were defined as symptom episodes of at least 2 days; lower respiratory illnesses included at least 1 day of either wet cough or wheeze. This report is based on 10,771 illnesses in the 1,315 subjects enrolled. Runny or stuffy nose was reported for most (93%) illnesses, wet cough in 33%, and wheeze in 6%. In comparison with the diagnoses made by a nurse practitioner, parent report of wet cough or wheeze was sensitive (93.4%) for detecting lower respiratory illnesses, but nonspecific with specificity of only 24.2%. The majority of the false-positive lower respiratory illnesses had the symptom of wet cough. The comparison of parent reports with outpatient records provided similar findings. Standardized reporting of respiratory illnesses can be achieved with a telephone surveillance system but classification of specific illnesses from the surveillance information may differ from diagnoses made by clinicians.

Cohort Studies↗
PubMed1993

Nitrogen dioxide and respiratory illnesses in infants.

Nitrogen dioxide is an oxidant gas that contaminates outdoor air and indoor air in homes with unvented gas appliances. A prospective cohort study was carried out to test the hypothesis that residential exposure to NO2 increases incidence and severity of respiratory illnesses during the first 18 months of life. A cohort of 1,205 healthy infants from homes without smokers was enrolled. The daily occurrence of respiratory symptoms and illnesses was reported by the mothers every 2 wk. Illnesses with wheezing or wet cough were classified as lower respiratory tract. Indoor NO2 concentrations were serially measured with passive samplers place in the subjects' bedrooms. In stratified analyses, illness incidence rates did not consistently increase with exposure to NO2 or stove type. In multivariate analyses that adjusted for potential confounding factors, odds ratios were not significantly elevated for current or lagged NO2 exposures, or stove type. Illness duration, a measure of illness severity, was not associated with NO2 exposure. The findings can be extended to homes with gas stoves in regions of the United States where the outdoor air is not heavily polluted by NO2.

Air Pollutants↗
PubMed1993

Sources of variability in posterior rhinomanometry.

Sources of variability in nasal airway resistance measured by posterior rhinomanometry were studied in 5 subjects tested on 5 different days and 56 subjects tested on 2 different days. On each day, a questionnaire on upper airway health and nasal symptoms was completed. The mean individual difference in nasal airway resistance between the 2 test days in the group of 56 subjects was 5.3% (SD 52.7%). Between-subject variability accounted for 74.9% and 72.5% of the total variability in the group of 5 and the group of 56 subjects, respectively. For the 5 subjects, by accounting for a change in upper airway symptoms or upper respiratory tract infection that occurred over the 5 test days, there was a significant decrease in the between-subject variability. The difference in sources of variation due to a change in upper airway symptoms was not seen in the group of 56 subjects. We conclude that the largest source of variability in nasal airway resistance is due to between-subject differences.

Adult↗
PubMed1993

Introduction and recommendations: working group on indoor air and other complex mixtures.

Air in indoor and outdoor environments typically contains many gaseous and particulate pollutants that may affect adversely any individual at sufficiently high concentrations and more sensitive individuals at lower concentrations. The public health relevance of addressing the effects of mixtures is becoming increasingly evident as we improve the concept of total personal exposure to pollution and obtain more data from personal monitoring. The papers within this volume represent the deliberations of a working group assembled with the goal of improving the epidemiologic approach to investigating the health effects of indoor air pollution and other complex mixtures. The group, composed of epidemiologists, human and animal toxicologists, and experts on biomarkers, comprehensively reviewed the methodologic issues involved in investigating complex mixtures. Members noted the deficiencies of current epidemiologic methodology for studying complex mixtures and called for broad-based advances in study design, exposure assessment, outcome assessment, and data analysis and interpretation. Understanding the health effects of complex mixtures will require multidisciplinary research using not only epidemiologic studies incorporating the new methods of exposure assessment but animal and clinical toxicology.

Air Pollutants↗
PubMed1993

Assessment of health effects in epidemiologic studies of air pollution.

As we increasingly recognize the complexity of the pollutants in indoor and outdoor microenvironments, a broad array of inhaled mixtures has assumed scientific, public health, and regulatory importance. Few adverse effects of environmental pollutants are specific, that is, uniquely associated with a single agent; the adverse effects that might be considered in an investigation of the consequences of exposure to an inhaled complex mixture are generally nonspecific. In the context of this paper, we will refer to binary mixtures as complex, though we realize that a more precise definition of complexity would restrict the term to mixtures of three or more constituents. Their causes potentially include not only pollutant exposures through the medium of inhaled air but other environmental agents, such as infectious organisms and radiation, and inherent characteristics of the exposed persons, such as atopy. We review the outcome measures that have been used in epidemiologic studies of the health effects of single pollutants and complex mixtures. Some of these outcome measures have been carefully standardized, whereas others need similar standardization and modification to improve sensitivity and specificity for investigating the health effects of air pollution.

Air Pollutants↗
PubMed1993

The epidemiology of lung cancer.

Lung cancer rates and mortality have risen in epidemic proportions in the United States and other industrialized nations during the 20th century. Case-control and cohort studies performed in the 1950s and 1960s firmly established cigarette smoking as the single greatest risk factor for lung cancer. In the United States, overall lung cancer mortality rates in men and women rose progressively from the 1950s. Fortunately, lung cancer incidence and mortality are now declining in middle-aged men. Smoking has significantly increased lung cancer rates among women and is on the rise in developing countries. Environmental agents found in the home and workplace, including radon and asbestos, have also been shown to increase lung cancer risk in both smokers and nonsmokers. Government regulations have helped curtail quantities of these and other atmospheric carcinogens. Efforts to reduce lung cancer risk must be continued and their scope expanded in order to have a global impact on the incidence and mortality of this fatal malignancy.

Air Pollution↗
PubMed1993

Environmental tobacco smoke concentrations in no-smoking and smoking sections of restaurants.

To characterize the effectiveness of a local ordinance that restricts smoking in restaurants to one third of the seating area, this study made simultaneous measurements of two markers of environmental tobacco smoke, respirable suspended particles and nicotine, in the smoking and no-smoking sections of seven restaurants. The mean concentrations of respirable suspended particles and nicotine were 40% and 65% lower, respectively, in the no-smoking than in the smoking sections, indicating substantial but not complete protection against exposure.

Air Pollution, Indoor↗
PubMed1993

Diabetes mortality among New Mexico's American Indian, Hispanic, and non-Hispanic white populations, 1958-1987.

OBJECTIVE: To determine the diabetes-related mortality rates among New Mexico's American Indians, Hispanics, and non-Hispanic whites over a 30-yr period. RESEARCH DESIGN AND METHODS: Death certificates were used to identify diabetes as an underlying cause of death by ethnic group in New Mexico during each 5-yr period from 1958 through 1987. The age-adjusted rates were calculated by ethnic group and sex, and temporal trends were examined. Comparison was made to U.S. white age-adjusted rates during the same time period. RESULTS: Age-adjusted diabetes mortality rates for American Indians and Hispanics increased throughout the 30-yr period, and far exceeded rates for New Mexico non-Hispanic whites and U.S. whites by the 1983-1987 time period. The rates increased most dramatically among the state's American Indians, increasing 550% among women and 249% among men. Hispanic women and men experienced increases of 112 and 140%, respectively. CONCLUSIONS: New Mexico's American Indian and Hispanic populations have higher diabetes mortality rates than non-Hispanic whites, and American Indian mortality rates have risen dramatically over the 30-yr period included in our study. Although the high prevalence of diabetes in American Indians and Hispanics is a major contributor to these rates, other factors may also influence the reported mortality rates.

Age Factors↗
PubMed1993

Assessment of heart rate as a predictor of ventilation.

The rate of ventilation and route of breathing (i.e., nasal versus oronasal) are potential determinants of pollutant doses to target sites in the lung. However, the lack of accurate methods for ambulatory measurement of ventilation has hindered estimation of exposure and dose in freely ranging individuals, complicating the interpretation of the relationships among exposure, dose, and response in epidemiological studies. The goal of this project was to develop and validate a method of monitoring ventilation for large-scale epidemiologic investigations. We estimated ventilation for individual subjects from ambulatory heart rate monitoring, using the relationship between ventilation and heart rate that had been obtained during exercise testing. Fifty-eight subjects participated in the study, which included healthy adults and children, and subjects with lung and heart disease. Subjects performed cycle exercise and tasks involving lifting and vacuuming. Work loads of progressive and variable order were used in the testing. Conventional methods were used to measure heart rate and total ventilation, and a sampling mask was developed to measure the partitioning of breathing between oral and nasal routes. The minute ventilation-heart rate relation was evaluated under steady-state and varying work loads. In a second phase, subjects wore wristwatch monitors that recorded their heart rates, minute by minute, throughout the day. Subjects recorded activities, locations, and levels of exertion. Two 16-hour monitoring periods were obtained from each subject. The laboratory findings documented considerable intersubject variability in the minute ventilation-heart rate relation with a two- to five-fold range in the coefficients describing the change in ventilation relative to heart rate. This variation implies that individual testing is required to derive accurate predictive equations. Minute ventilation-heart rate regressions for the maximal progressive exercise test and for the test with a nonprogressive submaximal work load sequence were comparable, indicating that varying the sequence of work loads does not substantially affect the minute ventilation-to-heart rate ratio. During upper body work (e.g., lifting), the minute ventilation-to-heart rate ratio was one-third greater than during lower body exercise. Diverse patterns of partitioning breathing between oral and nasal routes were observed with increasing oral ventilation in most subjects as work load increased. In the field, heart rate and activity patterns were monitored successfully in adults and children with low rates of instrument failure and noncompliance.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1993

Nitrogen dioxide and respiratory illness in children. Part I: Health outcomes.

We have carried out a prospective cohort study to test the hypothesis that exposure to nitrogen dioxide increases the incidence and severity of respiratory infections during the first 18 months of life. Between January 1988 and June 1990, 1,315 infants were enrolled into the study at birth and followed with prospective surveillance for the occurrence of respiratory infections and monitoring of nitrogen dioxide concentrations in their homes. The subjects were healthy infants from homes without smokers; they were selected with stratification by type of cooking stove at a ratio of four to one for gas and electric stoves. Illness experience was monitored by a daily diary of symptoms completed by the mother and a telephone interview conducted every two weeks. Illnesses with wheezing or wet cough were classified as involving the lower respiratory tract; all other respiratory illnesses were designated as involving the upper respiratory tract. Exposure to nitrogen dioxide was estimated by two-week average concentrations measured in the subjects' bedrooms with passive samplers. This analysis is limited to the 1,205 subjects completing at least one month of observation; of these, 823 completed the full protocol, contributing 82.8% of the total number of days during which the subjects were under observation. Incidence rates for all respiratory illnesses, all upper respiratory illness, all lower respiratory illnesses, and lower respiratory illness further divided into those with any wheezing, or wet cough without wheezing, were examined within strata of nitrogen dioxide exposure at the time of the illness, nitrogen dioxide exposure during the prior month, and type of cooking stove. Consistent trends of increasing illness incidence rates with increasing exposure to nitrogen dioxide were not evident for either the lagged or unlagged exposure variables. The effect of nitrogen dioxide exposure on illness occurrence during at-risk intervals of two weeks' duration was examined using the generalized estimating equation approach. In these multivariate analyses, none of the odds ratios was significantly elevated for unlagged nitrogen dioxide exposures, lagged nitrogen dioxide exposures, or stove type. Duration of illness was assessed in relation to the same exposure variables; illness duration and nitrogen dioxide exposure were not associated. We have found that indoor exposure to nitrogen dioxide is associated with neither the incidence nor the duration of respiratory illnesses. The study was designed to have sufficient power to detect effects of nitrogen dioxide exposure of magnitudes previously reported and in a range relevant to public health concern; the lack of association cannot be attributed to potential bias from misclassification of outcome or exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants↗
PubMed1993

Nitrogen dioxide and respiratory illness in children. Part II: Assessment of exposure to nitrogen dioxide.

Repeated measurements of nitrogen dioxide were obtained from 1988 to 1991 in the homes of 1,205 infants living in Albuquerque, NM. Passive diffusion samplers were used to obtain a series of two-week integrated measurements from the home of each infant for use in a cohort study of the relation of residential exposure to nitrogen dioxide and respiratory illnesses. Information on stove use and time spent inside the residence was collected at two-week and two-month intervals, respectively. During the winter, in the bedrooms of homes with gas cooking stoves, mean nitrogen dioxide concentrations were 21 parts per billion (ppb); mean concentrations in the living room and kitchen were 29 ppb and 34 ppb, respectively. In homes with electric cooking stoves, the mean bedroom concentration was 7 ppb during the winter. Lower indoor concentrations were observed during the summer in homes with both gas and electric stoves. On average, infants spent approximately 12.3 hours per day in their bedrooms, 7.3 hours in the living rooms, 35 minutes in the kitchens, and 3.8 hours out of their homes. (As a condition of participation, none of the infants spent more than 20 hours per week in day care outside of their homes). The mean time infants spent in the kitchen during cooking was approximately nine minutes per day. We tested whether exposures of infants living in homes with gas stoves could be reasonably estimated by measurements in the bedroom in comparison with time-weighted average concentrations based on time-activity data and simultaneous nitrogen dioxide measurements in the kitchen, living room, and bedroom. In 1,937 two-week intervals from 587 infants, 90% of time-weighted exposure (on the three-level classification used in this study) estimates were in agreement with estimates based on bedroom concentrations alone. The agreement of the time-weighted nitrogen dioxide exposure estimates with the bedroom concentrations is attributed to limited amounts of cooking stove use (the mean was 29 minutes per day), small room-to-room differences in nitrogen dioxide concentrations (the mean kitchen-bedroom difference was 12 ppb), and the relatively large proportion of time that infants spent in their bedrooms.

Air Pollution, Indoor↗
PubMed1992

Geographic variation in the treatment of localized breast cancer.

BACKGROUND: Breast-conserving surgery followed by radiation therapy is as effective as modified radical mastectomy in treating women with localized breast cancer, as demonstrated by clinical trials reported during the 1980s. The extent to which breast-conserving surgery has been adopted in various regions of the United States is not known. METHODS: We assessed variations in the use of breast-conserving surgery from 1983 to 1986 in 18,399 non-Hispanic white, 324 Hispanic, and 1174 black women with breast cancer in nine areas of the United States, using data from the Surveillance, Epidemiology, and End-Results Program of the National Cancer Institute. RESULTS: The proportion of white women with localized breast cancer who underwent breast-conserving surgery ranged from 9.2 percent (Iowa) to 32.1 percent (Seattle) in 1983-1984 and from 19.6 percent (Iowa) to 41.5 percent (Seattle) in 1985-1986. Between 1983 and 1986, the use of breast-conserving surgery increased in each area, but the relative rankings of the areas changed little. The frequency of the use of breast-conserving surgery in black and Hispanic women was comparable to that in white women. The proportion of women who received radiation therapy after breast-conserving surgery also varied geographically and increased from 1983 to 1986 in all areas. Older women in all areas and black women in Atlanta and Detroit were less likely than other women to receive radiotherapy after breast-conserving surgery. CONCLUSIONS: There is marked variation in the United States in the use of breast-conserving surgery for localized breast cancer. The variation is not explained by demographic factors, although race and age affect the use of radiotherapy after breast-conserving surgery.

Black or African American↗
PubMed1992

Mutations of p53 and ras genes in radon-associated lung cancer from uranium miners.

Radon increases the risk of lung cancer in smoking and non-smoking underground miners. To investigate the mutational spectrum associated with exposure to high levels of radon, we sequenced exons 5-9 of the p53 tumour suppressor gene and codons 12-13 of the Ki-ras protooncogene in 19 lung cancers from uranium miners exposed to radon and tobacco smoke. Mutations were not found in Ki-ras, but 9 p53 mutations, including 2 deletions, were found in 7 patients by direct DNA sequencing after polymerase chain reaction amplification of DNA from formalin-fixed, paraffin-embedded tissue. In tumours from 5 patients, the mutation produced an aminoacid change and an increased nuclear content of p53 protein. The tumours with either a stop codon or frame-shift deletion in the p53 gene were negative by immunohistochemistry. None of the mutations were G:C to T:A transversions in the coding strand of the p53 gene, which are the most frequent base substitutions associated with tobacco smoking, and none were found at the hotspot codons described in lung cancer. The observed differences from the usual lung cancer mutational spectrum may reflect the genotoxic effects of radon.

Aged↗
PubMed1992

Effect of ozone on platelet activating factor metabolism in phorbol-differentiated HL60 cells.

The mechanisms of ozone (O3) toxicity in the lung may involve the formation of lipid inflammatory mediators. We have previously demonstrated that exposure to O3 in vitro results in increased accumulation and release of platelet activating factor (PAF) in the macrophage-like cell line HL60 differentiated with phorbol ester (dHL60). In the present study we have examined possible biochemical mechanisms responsible for the O3-induced increase in PAF levels in dHL60 cells. Specifically, we studied the effect of O3 on phospholipase A2 (PLA2), acetyltransferase, acetylhydrolase, and reacylation activities. dHL60 cells were exposed to 1.0 ppm O3 or air alone. O3 exposure was found to significantly decrease dHL60 cell acetylhydrolase activity by 36%. Additional experiments demonstrated that extracellular acetylhydrolase activity, but not intracellular acetylhydrolase activity, was inhibited by O3 exposure of dHL60 cells. O3 exposure resulted in a small (13%) but statistically significant reduction in reacylation activity in dHL60 cells. In addition, a significant (22%) contribution of PLA2 activation to the O3-induced increase in PAF levels was also found. Basal and calcium ionophore-induced acetyltransferase activity was found to be unaffected by exposure of dHL60 cells to O3. These data suggest that in vitro exposure to O3 affects both synthetic and degradative pathways of PAF metabolism in dHL60 cells.

Acetylation↗