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Biomedical subjects

J M Samet

Publications and source records attributed to J M Samet.

At least 271 records · Page 15Linked to original sources
PubMed1982

Respiratory disease in a New Mexico population sample of Hispanic and non-Hispanic whites.

To characterize the epidemiologic features of respiratory diseases among Hispanics, we conducted a prevalence survey in Bernalillo County, New Mexico. The ATS-DLD-78 respiratory symptoms questionnaire was completed by 633 Hispanics and 1,038 Anglos (non-Hispanic whites) with an overall response rate of 72%. The prevalence of major respiratory diseases differed between the groups. Physician-confirmed chronic bronchitis or emphysema, and asthma were reported less often by Hispanics. Although patterns of cigarette usage (current, previous, never) were similar, current and cumulative cigarette consumption was significantly lower in Hispanics. Most differences in symptom frequency and the lower Hispanic prevalence of chronic bronchitis or emphysema were attributable to lower cigarette consumption by Hispanics. However, the prevalence of asthma remained significantly lower among Hispanics after controlling for cigarette smoking. These results documented differences in the prevalence of respiratory disease between the Hispanics and Anglos, which were partially explained by the distributions of known risk factors.

Adult↗
PubMed1982

Effect of cigarette tar content and smoking habits on respiratory symptoms in women.

Standardized respiratory disease questionnaires (ATS-DLD-78) were administered to 5,686 adult women. Risk factors were evaluated by logistic analysis that adjusted for multiple potential confounding factors. Among current smokers, the number of cigarettes smoked per day was consistently the strongest risk factor for chronic cough, chronic phlegm, wheeze, and dyspnea. The odds ratios for these symptoms in a smoker of 25 or more cigarettes per day relative to a smoker of 1--14 cigarettes per day were 4.74, 4.21, 2.05, and 3.71, respectively. Ex-smokers showed risks between those of current and never smokers. Cigarette tar content was a significant independent risk factor for chronic cough (p = 0.005) and of borderline significance for chronic phlegm (p = 0.077). High tar cigarette smokers in this population (average, 22 mg) had an odds ratio of 2.01 for chronic cough and 1.59 for chronic phlegm relative to low tar cigarette smokers (average, 7 mg). The effect of cigarette tar was linear and independent of cigarettes smoked per day. Smoke inhalation was a significant risk factor for chronic cough (p = 0.029) and for chronic phlegm (p = 0.038). Tar content and smoke inhalation were not significant risk factors for wheeze or dyspnea. Cigarette particulate content (tar) appears to be causally linked to cough and phlegm production., but the association of cigarette smoking and symptoms of wheeze and dyspnea may be more strongly related to the vapor phase of cigarette smoke.

Adolescent↗
PubMed1980

An assessment of physician knowledge of epidemiology and biostatistics.

A review was conducted of 585 articles in the medical literature, and the articles were categorized by study design and by statistical techniques employed. In the majority, statistics were utilized primarily for data description and hypothesis-testing. Descriptive studies were most frequent, and only a minority were epidemiological investigations. A questionnaire designed to assess knowledge of biostatistics and epidemiology relevant to this literature was administered to internists and medical house staff at a teaching hospital. Of 229 questionnaire recipients, 141 responded and achieved a mean score of 7.4 with 10.0 possible. Practicing physicians had a significantly lower mean score than house staff and full-time faculty. Scores were higher for the 44 percent of respondents who reported prior training in epidemiology or in biostatistics. The results of the journal review suggest that knowledge of basic biostatistics and of study design is important for reading medical literature. Physicians with prior training in epidemiology and in biostatistics appear to be better prepared for this task.

Biometry↗
PubMed1980

Respiratory disease mortality in New Mexico's American Indians and Hispanics.

To determine the effect of ethnic group on respiratory disease occurrence, average annual sex, ethnic, and disease specific mortality rates for the period of 1969 to 1977 were calculated for New Mexico's American Indian, Hispanic, and Anglo populations. Incidence data were available for respiratory tract cancer. This study corroborates previous findings of reduced mortality from lung cancer in American Indians of both sexes and in Hispanic males. American Indian mortality from tuberculosis and from influenza and pneumonia was high. Hispanic males and American Indians of both sexes showed low mortality rates for chronic obstructive pulmonary disease (COPD). Differing cigarette usage is the most obvious explanation for the variations in COPD and lung cancer occurrence with ethnic group.

Adolescent↗
PubMed1979

Absence of synergism between exposure to asbestos and cigarette smoking in asbestosis.

To assess both independent and synergistic effects of exposure to asbestos and cigarette smoking on the development of asbestosis, survey data from 4 groups of workers exposed to asbestos were analyzed with multivariate statistical models. Survey methods were standardized and included for the 383 subjects a respiratory symptoms questionnaire, occupational history, physical examination, pulmonary function testing, and a chest radiograph. Exposure to asbestos and cigarette smoking were assessed by questionnaire. Synergism between the 2 exposures was not present for previously identified manifestations of asbestosis including bilateral fine crackles, clubbing, dyspnea, radiographic abnormality, decreased forced vital capacity, and decreased single-breath diffusing capacity of the lung for CO. However, additive, independent effects of these 2 exposures were present for each of these parameters.

Adult↗
PubMed1978

A historical and epidemiologic perspective on respiratory symptoms questionnaires.

Since 1960 the British Medical Research Council (MRC) standardized questionnaire on respiratory symptoms has been used in epidemiologic investigations of chronic respiratory diseases. This review describes the validity, reliability, and susceptibility to bias of the MRC questionnaire. The validity of the phlegm questions as a sensitive index of sputum production has been established but adequate validation of other symptom questions has been hindered by the absence of appropriate, independent criteria for comparison. Consistency of response averages 80 per cent for symptom questions and may reach 99 per cent for reporting of smoking habits. With proper use, the results of the MRC questionnaire are not biased by the observer, by the season of administration, or by method of administration. Modification of the questionnaire by individual investigators may lead to bias when comparisons are made between studies. Because a large literature based on the MRC questionnaire is now available, any new respiratory symptoms questionnaires should be compatible with the MRC questionnaire, and should be calibrated against it.

Boston↗
PubMedDate not supplied

Health effects of air pollution due to coal combustion in the Chestnut Ridge Region of Pennsylvania: results of cross-sectional analysis in adults.

Respiratory questionnaires (ATS-DLD-78) were administered to 5557 adult women in a rural area of Western Pennsylvania to evaluate the health effects of air pollution resulting from coal combustion. Air pollution data were derived from 17 air quality monitor sites and stratified to define low, medium, and high pollution areas. The means of 4 yr (1975-1978) annual averages for sulfur dioxide in each strata were 62, 66, and 99 micrograms/m3, respectively. Total suspended particulates were not tested as a risk factor because they reflected air pollution from sources other than coal combustion (e.g., agricultural, road dusts). Risks of respiratory symptoms were evaluated in a multiple logistic model that adjusted for several potential confounding factors. The risk of "wheeze most days or nights" in nonsmokers residing in the high and medium pollution areas was 1.58 and 1.26 (P = .02), respectively, relative to residents in the low pollution area. In the subset of residents who had lived in the same location for at least 5 yr, relative risks increased to 1.95 and 1.40 (P less than .01), respectively. An increased risk of grade 3 dyspnea in nonsmokers was associated with sulfur dioxide but did not achieve statistical significance (P = .11), and there was no association of cough or phlegm and air pollution in nonsmokers. Cigarette smoking characteristics were the major determinant of respiratory symptoms in smokers, and no independent association of air pollution was found. This study suggests that wheezing may be associated with ambient exposure to sulfur dioxide in nonsmokers, but no effect of sulfur dioxide on cigarette smokers was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Altitude and mortality from chronic obstructive lung disease in New Mexico.

This study tested the hypothesis that altitude increases mortality from chronic obstructive lung disease (COLD) in New Mexico. A death was attributed to COLD if it resulted from chronic bronchitis, emphysema, or chronic obstructive lung disease, according to the Eighth Revision International Classification of Diseases, Adapted for Use in the United States. New Mexico's average annual ethnic and sex-specific mortality rates from COLD were calculated using death certificate data for the period 1969 to 1977. Deaths were assigned to altitude groups according to the county of residence at the time of death. Mortality rates for whites exceeded nationwide rates at all altitudes. However, mortality rates showed no increase with altitude. In fact, mortality from COLD decreased significantly with altitude for non-Hispanic white (Anglo) males (P less than .02). Immigration of Anglos to the lower altitudes of New Mexico probably explains these results.

Altitude↗
PubMedDate not supplied

A study of respiratory illnesses in infants and nitrogen dioxide exposure.

Toxicologic and epidemiologic studies have elevated concern that exposure to nitrogen dioxide (NO2) in outdoor and indoor air may increase the frequency and severity of respiratory infections. We have developed and implemented a prospective cohort study to test the hypothesis that exposure to NO2 increases the incidence and severity of respiratory infections during the first 18 mo of life. This study, which was based on extensive pilot research, was designed to address the potential limitations of misclassification, confounding, and inadequate power. Enrollment of 1,315 subjects has been completed. This paper reviews the methods used in the study, characteristics of the enrolled subjects, NO2 concentrations in the homes of study participants, and rates of illness occurrence.

Air Pollution, Indoor↗
PubMedDate not supplied

Evaluation of the relationship between heart rate and ventilation for epidemiologic studies.

Estimation of pulmonary exposure and dose in air pollution epidemiology has been impaired by the lack of methods for directly measuring ventilation in ambulatory subjects. Heart-rate monitoring offers an approach to estimate ventilation by using ventilation-on-heart-rate (VE-HR) regressions established during exercise testing to estimate ventilation in the field. Conventional methods and protocols for testing were used to evaluate the relationship between VE and HR during three tasks: (1) exercising on a cycle ergometer, (2) lifting, and (3) vacuuming. The relationship between VE and HR was curvilinear and was best fit with linear regression models, using a natural log transformation of VE. Considerable interindividual variability in slopes and intercepts was observed across all types of exercise tests. The variability about the fitted regression lines for individual subjects was minimal; for example, individual R2 values for the maximum exercise test on 15 men ranged from 0.90 to 0.99 (mean = 0.97). The regression slopes established during upper-body exercise were greater by approximately 30%, relative to those derived in lower-body exercise (paired t test, p < .001). However, VE-HR regression slopes derived from tests in which progressively increasing workloads were used were comparable to those obtained during variable and nonprogressive protocols. These findings indicate that predictive accuracy is maximized by deriving VE-HR regressions for individual subjects and for both lower- and upper-body activities.

Adolescent↗
PubMedDate not supplied

Oronasal distribution of ventilation at different ages.

The route of breathing, oral or nasal, is a determinant of the doses of inhaled pollutants delivered to target sites in the upper and lower respiratory tracts. We measured partitioning of ventilation, using a divided oronasal mask during a submaximal exercise test, in 37 male and female subjects who ranged in age from 7 to 72 y. The following four patterns of breathing were evident during exercise: (1) nasal only (13.5%), nasal shifting to oronasal (40.5%), oronasal only (40.5%), and oral only (5.4%). Children (i.e., 7-16 y of age) displayed more variability than adults with respect to their patterns of ventilation with exercise. Young adults (i.e., 17-30 y of age) who initially breathed nasally with exercise switched to oral ventilation at a lower percentage of the previously measured maximum ventilation (10.8%) than older subjects (31.8%). The partitioning of ventilation between the nasal and oral routes follows complex patterns that cannot be predicted readily by the age, gender, or nasal airway resistance of the subject.

Adolescent↗
PubMedDate not supplied

Increased expression of cyclooxygenase 2 mediates oil fly ash-induced lung injury.

We have previously shown that in vitro exposure to the combustion-derived ambient air pollutant residual oil fly ash (ROFA) induces the expression of prostaglandin H synthase 2 (COX2) in human airway epithelial cells. To determine the role of prostaglandins and COX2 expression in ROFA-induced lung injury in vivo, we have examined the effect of intratracheal ROFA instillation on COX2 expression, prostaglandin synthesis, and indices of pulmonary injury and inflammation in adult Sprague-Dawley rats. ROFA treatment induced a marked increase in the level of prostagladin E2 (PGE2) recovered in the bronchoalveolar lavage fluid (BALF), which was effectively decreased by pretreating the animals with the specific COX2 inhibitor NS398. Immunohistochemical analyses of rat airways showed concomitant expression of COX2 in the proximal airway epithelium of rats treated with ROFA. Increases in BALF protein, but not interleukin 6 (IL-6) increases or ROFA-induced polymorphonuclear neutrophils (PMN) influx into the airway, were blunted by administration of NS398 prior to ROFA instillation. These data demonstrate that prostaglandins mediate lung injury induced by exposure to ROFA and implicate increased expression of COX2 as a mechanism that contributes to the toxicity of metal-laden ambient particulate matter.

Air Pollutants↗
PubMedDate not supplied

Keratoacanthoma as a complication of arterial puncture for blood gases.

In July 1979, a 72-year-old white woman presented to the Bernalillo County Medical Center Emergency Department with complaints of shortness of breath and wheezing. She had been asthmatic since childhood. Current management included bronchodilator therapy and continuous low flow oxygen. An apparently curative left radical nephrectomy had been performed in 1978 for renal cell carcinoma. Her evaluation in the emergency room included multiple attempts at right radial artery puncture for blood gases. The arterial blood gases were obtained only after repeated efforts by several individuals. The patient was discharged from the emergency room after receiving subcutaneous terbutaline and intravenous aminophylline. Approximately one week later, she noticed a swelling on her right wrist at the site of the punctures. Over the ensuing three weeks, the lesion doubled in size and became painful. In chest clinic, one month after emergency room visit, we found a 1 cm by 1 cm raised erythematous tender nodule on the right wrist overlying the radial artery pulse. We did not hear a bruit, the lesion did not feel fluctuant, and attempts to aspirate fluid were unsuccessful. Because we thought the lesion represented local infection, we began oral antibiotic therapy. The lesion was unchanged after 1 1/2 weeks of therapy and was excised. Pathologic examination showed a well-defined cutaneous nodule with histology diagnostic of a keratocanthoma. The patient developed a recurrence of the tumor at the excision site a few weeks later and required a wide excision, also under local anesthesia. She has since remained clinically free of recurrent tumor.

Aged↗
PubMedDate not supplied

Metal storage and transport proteins increase after exposure of the rat lung to an air pollution particle.

With the single exception of mercury, all metals in the atmosphere are associated with particles. The lungs are subsequently exposed to metals present in air pollution particles on a continuous basis. Because metal exposure can be associated with an oxidative stress, a mechanism that isolates the metal in a chemically less reactive form would be of benefit. We tested the hypothesis that the concentrations of both lactoferrin and ferritin in the rat lung increase after exposure to a metal-rich emission source air pollution particle. Using immunohistochemistry, we characterized changes in the concentrations of ferritin and lactoferrin after exposure of rats to an emission source air pollution particle. Lavage metal concentrations, measured by inductively coupled plasma emission spectroscopy, increased 4 hr after exposure to an oil fly ash. After exposure to this metal-rich emission source air pollution particle, ferritin concentrations in the lower respiratory tract increased. Comparable to the iron-storage protein, concentrations of both lactoferrin and transferrin were elevated after exposure. The greatest concentrations of ferritin, lactoferrin, and transferrin occurred at approximately 24 hr after exposure to the air pollution particle. Levels then decreased, and by 96 hr after instillation of the oil fly ash, ferritin, lactoferrin, and transferrin were not elevated relative to those animals exposed to saline. We conclude that, in response to an emission source air pollution particle with high concentrations of metals, there is an increase in ferritin, lactoferrin, and transferrin concentrations in the lungs of the host. The function of these increases in iron-binding proteins may be to control the oxidative stress associated with the exposure to metals.

Air Pollution↗