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Biomedical subjects

M D Lebowitz

Publications and source records attributed to M D Lebowitz.

At least 91 records · Page 5Linked to original sources
PubMed1990

Environmental contaminants and low-level cancer risks: perceptions and scientific strategies.

Scientific and public perceptions concerning low-level lung cancer risks may vary. Recently the public has been more convinced of causal links between low-level risk agents and cancer, and more interested in prevention of environmental exposures, especially those induced by others. Thus, scientific strategy is partly driven by the public need to resolve issues concerning the importance of low-level exposures and risks. Further, investigators have been challenged intellectually to create methodologies in order to study some of these relationships further, and scientific curiosity has been stimulated by the difficulties of pursuing such investigations. The importance of host characteristics, including the genetic bases of susceptibility, has become a major theme. Likewise, host behaviour has become a potential positive factor (e.g. diet) as well as a negative factor in the risk model for low-level agents. This paper discusses some of the information available on low-level agents and some of the methodological issues involved in studying them. The importance of measuring exposure as well as response is stressed, especially multi-pollutant exposures and interactions with host behaviour.

Asbestos↗
PubMed1990

Methodological issues in the epidemiological investigations of lung cancer related to low-level risks.

There are several major issues that create great difficulties in the study of low-level risks for lung cancer. Further attention needs to be addressed to the difficulties in design, ascertainment, classification, confounding and analysis found in the environmental epidemiological aspects of the investigation. Host predisposition is an important factor that requires further characterization in the process of conducting these environmental epidemiological investigations. Within the exposure assessment aspects of these investigations, major difficulties arise from the need to obtain total exposure estimates, dose estimates and in evaluating the interactions of the several pollutants of concern in exposure settings of interest. Low-level risks for lung cancer imply difficulties in the assessment of exposure-dose pattern. Further, bio-markers are needed to focus more on dose. Further, low-level risk ratios produce difficulties in distinguishing the effects of confounders. In order to facilitate further studies of lung cancer related to low-level risks, we will have to create new, more specific, and more efficient study designs. These studies will require much better exposure assessment and case ascertainment than typical of previous studies, and more complete measurement of confounders.

Environmental Exposure↗
PubMed1990

Longitudinal analysis of the effects of acute lower respiratory illnesses on pulmonary function in an adult population.

The data from a longitudinal population study in Tucson, Arizona, were used to evaluate the effects of acute lower respiratory illnesses on pulmonary function in subjects over 25 years of age. In five of nine surveys performed during the first 13 years of follow-up (1972-1985), similar questions were asked concerning chest colds occurring in the past few years. There were 1,151 men and 1,473 women who had questionnaire and spirometric data collected in at least one of these surveys. The random effects longitudinal model with first-order autoregressive error structure was used in the analysis of changes in pulmonary function after the acute illness episode, adjusted for the effects of age, height, cigarette smoking, and chronic respiratory diseases. The analyses indicated that pulmonary function is reduced for several years after a single chest cold in men and after multiple chest colds in women. After an episode of pneumonia, pulmonary flow indices were reduced, with lower values sometimes persisting for several years.

Adult↗
PubMed1990

Carbon monoxide diffusing capacity, other indices of lung function, and respiratory symptoms in a general population sample.

To assess the relationships among single-breath diffusing capacity for CO (DLCOsb) (13), respiratory symptoms, and cigarette smoking in a general population sample, the data of 718 men and 894 women 20 yr of age or older were analyzed, and comparisons were performed with flow-volume curve (MEFV) variables and the slope of the alveolar plateau (DN2%/L) as well. Percent predicted DLCOsb and its correction for alveolar volume (DL/VA) were significantly lower in smokers than in nonsmokers. The relationship of presence/absence of respiratory symptoms and cigarette smoking with DLCOsb and DL/VA was significant. DLCO indices were almost always selected as discriminant variables in multivariate analysis between asymptomatic and symptomatic subjects. Poor concordance among lung function tests was evident: in men, 30% with abnormal (i.e., lower than 97.5% percentile) and 21% with normal DLCO indices also had abnormal MEFV parameters and/or DN2%/L. In women, the corresponding figures were 24 and 10%, respectively. In men, when considering only DLCO indices, the percentage of symptomatic subjects with abnormal lung function tests ranged from 33% in those with at least one symptom to 45% in those complaining of dyspnea. When the proportion of symptomatic subjects with DN2%/L and MEFV abnormalities were added, it increased to 56 and 66%, respectively. However, in women the proportion of symptomatic subjects with abnormal lung function indices was very small. These results indicate the usefulness of including CO diffusing capacity in epidemiologic surveys in the detection of abnormalities.

Adolescent↗
PubMed1990

Comparisons of spirometric reference values and the proportions of abnormal subjects among male smokers and those symptomatic in a community population.

A comparison was performed of various population reference equations for several spirometric measurements. The objective was to determine if the different equations yielded similar distributions of the percent predicted values, similar reference values for asymptomatic nonsmokers (i.e., normal subjects), criteria (or cutoff points) for who might be defined statistically as normal, and similar proportions of smokers and symptomatic subjects who would fall below the criteria values and thus be considered statistically abnormal. The cross-sectional study population of adults in Tucson, subjects of an ongoing study, was used. Most of the equations yielded reasonably similar distributions of percent predicted values. Older and/or more unusual equations did not yield similar results. Using the lower 95th percentile criteria yielded similar cutoff points as reference values for statistical normality, and similar proportions of statistically abnormal among various smoking and symptomatic groups; some of the equations used did not. When the criteria used were the lower 1.645 SEE, or the published criteria, the proportions considered statistically abnormal were very low or very high; again, some equations gave very disparate results. The first conclusion was that the use of the lower 95th percentile criteria was more sensitive and specific. It was concluded also that most equations yield sufficiently similar results such that the choice of reference equation from those available would depend on other criteria.

Adult↗
PubMed1990

Relationships between pulmonary function and changes in chronic respiratory symptoms. Comparison of Tucson and Cracow longitudinal studies.

Parallel analyses of data from two longitudinal studies, one in Poland and one in the United States, were performed to assess the relationships between pulmonary function and respiratory symptoms. Similar relationships were seen in the both cities using the same methods of analysis. The rate of FEV1 decline and its final level were related to the prior presence of attacks of breathlessness or to a syndrome that also included wheezing and diagnosed asthma. Initial FEV1 level was lower in subjects with dyspnea appearing during the follow-up than in the never-symptom group. These relationships were independent of smoking habits. The consistencies in the parallel analyses strengthen the relationships observed. In Tucson, Ariz, the FEV1 decline in smokers with persistent chronic cough was greater than that due to separate effects of the symptom and smoking. This suggests that chronic cough may be an indicator of an increased effect of tobacco smoke on pulmonary function.

Adult↗
PubMed1990

Epidemiology of chronic obstructive pulmonary disease.

Morbidity and mortality rates for chronic obstructive pulmonary disease (COPD) have been increasing over time. Epidemiologic investigators of COPD have been exploring the reasons for these increases through prevalence surveys and longitudinal studies. This article examines some of the recent findings.

Air Pollution↗
PubMed1989

The new standard environmental inventory questionnaire for estimation of indoor concentrations.

Several investigators have developed indoor air quality questionnaires for use in field studies. The approach used in many of them have numerous features in common, but most of them are unique in their content (wording, format, item selection). It is thought that indoor air quality research could be greatly advanced if the primary or fundamental questions and instruments could be consolidated. The use of a basic set of "standard" questions would permit intercomparison of results from different research studies. It is generally agreed that environmental inventory questionnaires (EIQ) help to classify, at least in screening, relative concentration estimates, which precede exposure estimation. Thus, such instruments are not equivalent to monitoring for exposure assessment. However, data linkage and mega data bases are important for some comparative analyses of exposure assessment and exposure-response relationships. Standard instruments such as the EIQ are useful as a screening device to precede other tests to allow identification of potentially high exposure situations. They can also amplify information from other tests. General usage of standard questionnaires and protocols can lead to cumulative improvements in data collection, specificity and effectiveness. This has been the rationale for the present efforts by investigators to form a standardized environmental inventory questionnaire, under the auspices of the U.S. Environmental Protection Agency (EPA), Gas Research Institute (GRI), and Electric Power Research Institute (EPRI).

Air↗
PubMed1989

Commingling in the distributions of immunoglobulin levels.

Commingling in the distributions of five immunoglobulins from a Canadian sample of 810 Caucasians and IgE from a US sample of 935 Caucasians was investigated. For both the Canadian and US samples significant commingling was found in the child's but not the adult's IgE distribution. Contrary to expectations based upon the major gene hypothesis for IgM, we found no evidence for commingling in the IgM distribution. Finally, the distributions of IgA, IgD and IgG all evidenced significant commingling that may be the result of a single gene effect or the operation of a discrete environmental effect.

Adult↗
PubMed1989

Smoking habit and bronchial reactivity in normal subjects. A population-based study.

The relationship between smoking habits and airway responsiveness has been studied in a cross-sectional sample of subjects in a small Lombardy (Italy) town. The subjects were between 15 and 64 yr of age; they were representative of the general population. There were 295 normal nonsmokers, 70 normal smokers, and 50 past smokers. All clinically asymptomatic and functionally normal subjects underwent methacholine challenge. The distribution of responsiveness to methacholine (as expressed by LnPD15FEV1) was found to be significantly different between these normal smokers and nonsmokers. A multinomial logistic regression model showed a statistically significant difference in the response to the challenge on the basis of pack-years. When the number of years of smoking and the daily number of cigarettes were separately considered, the current amount had the significant correlation with LnPD15FEV1. Bronchial reactivity for past smokers was found not to be different from that for normal nonsmokers. We conclude that smoking habits, especially current habits, affect bronchial reactivity even in the absence of airway obstruction.

Adolescent↗
PubMed1989

On the temporal relationships between lung function and somatic growth.

A sample population of healthy nonsmoking male (n = 416) and female (n = 608) subjects derived from all non-Hispanic white subjects 5 to 60 yr of age enrolled in the Tucson Epidemiological Study of Airway Obstructive Disease was studied to evaluate the temporal relationships between various pulmonary function measures and somatic growth. Pulmonary function measures derived from the maximal expiratory flow volume (MEFV) curve included FVC, FEV1, maximal expiratory flow after 50% of vital capacity had been expired (Vmax50), and maximal midexpiratory flow (FEF25-75). The lung function and somatic growth longitudinal data were characterized by a nonparametric polynomial smoothing spline model. This procedure yields an optimal fitted curve through the data, an estimate of the growth velocity curve, and 95% confidence bands. Temporal relationships between the fitted growth curves were determined examining the ages at which the growth velocity peaks (GVP) occur. In addition, the age of growth cessation was estimated using lower limits of the 95% confidence bands of each growth velocity curve. The results indicate that the point estimates of the somatic GVPs precede all peak lung function measurements derived from the MEFV curve in both males and females. The only statistically significant difference between when the GVPs for somatic growth and functional lung growth occurred was for FEV1 and FEF25-75 in males, though similar trends were apparent in all other variables, suggesting that the timing of maximal body growth velocity precedes that of maximal lung functional growth and that the early growth spurt in females includes the lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

The trends in airway obstructive disease morbidity in the Tucson Epidemiological Study.

An analysis of the incidence and prevalence rates of airway obstructive diseases (AOD) has been conducted in adults in the Tucson community population under study, covering nine surveys, 1972 to 1985 inclusive. It was found that rates of diagnoses increased from initial surveys within each age group, possibly due to the effect of the study per se. The rates increased even more in each age cohort until age 65, demonstrating the effects of aging. Cohort changes in smoking were greater than cross-sectional differences between age groups. The incidence rates of diagnoses with functional impairment are about 7/1000 and are greater in smokers and in males. The new cases of AOD were defined both by functional impairment and/or physician diagnoses. They had lower pulmonary function at the initial examination. This implies a natural history of AOD that starts well before clinical diagnoses. New cases of diseases had a variegated set of associated risk factors. In addition to smoking, there were contributions made by reports of childhood respiratory disease, family history, occupational exposures, alcohol consumption, and IgE (in asthma alone or with other AOD). Use of reported diagnostic endpoints as well as functional impairment contributed more to the understanding of the possible etiology of AOD. Some increases in AOD rates may be a function of more careful study, but cohort rate increases seen in a careful longitudinal study show that a real increase in AOD is likely.

Adult↗
PubMed1989

Effects of childhood and adolescence-adulthood respiratory infections in a general population.

The role of childhood respiratory infections before 12 yrs of age (CRI) and during adolescence-adulthood (ARI) was studied in a general population sample (n = 3,289), living in an unpolluted area of Northern Italy. The presence of respiratory symptoms and diseases, as well as risk factors for obstructive airways disease (OAD), was assessed by a standardized questionnaire. Forced vital capacity and derived expiratory flows, and single-breath diffusing capacity were measured using computerized instrumentation. There were 1,185 (36.2%) subjects who reported pertussis (PT), 374 (11.4%) recurrent chest colds, pneumonia and croup, singly or in combination, with or without pertussis (CRI), and 1,718 (52.4%) reported no respiratory infections in childhood (NOCRI). Prevalence rates of respiratory symptoms and diseases were significantly higher in subjects of the CRI group in all ages, and in older smokers. Wheeze and attacks of shortness of breath with wheeze were significantly higher in younger nonsmoking subjects with a history of CRI. Respiratory symptoms and diseases were not more prevalent in subjects of the PT group. Prevalence rates of respiratory symptoms and diseases were significantly higher in subjects with a history of ARI, both in smokers and nonsmokers. Lung function parameters adjusted for sex, age and smoking were significantly lower in CRI subjects; PT subjects showed lower values than NOCRI subjects. A significantly higher prevalence rate of ARI was present in subjects who reported CRI, both in smokers and nonsmokers. Subjects with both CRI and ARI showed the highest prevalence of respiratory symptoms and diseases. In addition, they had the lowest lung function values regardless of smoking habit.

Adolescent↗
PubMed1988

Effects of parental smoking and other risk factors on the development of pulmonary function in children and adolescents. Analysis of two longitudinal population studies.

Two sets of longitudinal pulmonary function data have been analyzed to determine the effects of parental smoking on the development of lung function in children and adolescents. One community population was obtained in East Boston, Massachusetts, and one in Tucson, Arizona; both studies started in the 1970s and are still continuing. These data sets, analyzed by different methods, have yielded different answers in regard to the effects of parental smoking. A common analytical approach is now used to determine whether the different outcomes were due to the different analytical methods previously used. These results were compared with results from a similar parallel analysis conducted by the East Boston investigators and indicate that the differences found were not due to the methods used for analysis. Reasons for the differences found are explored. The most likely factor responsible for the disparate results is the exposure difference in the two populations, related to proportion and amount of maternal smoking and different indoor environments.

Adolescent↗
PubMed1988

Objective radiographic criteria to differentiate cardiac, renal, and injury lung edema.

To assess the value of the chest radiograph in differentiating various types of pulmonary edema, we retrospectively analyzed 119 films of patients with pulmonary edema caused by left heart decompensation (group 1;N = 56), renal failure (group 2; N = 19), and lung microvascular injury (group 3; N = 44). Chest radiographs were examined independently by two trained observers, unaware of the clinical diagnosis, according to a standardized reading table. The two observers assigned chest films to the corresponding group with an accuracy of 86% and 90%, respectively. To test the observers' objectivity, we used radiographic findings as input variables for discriminant analysis. Computer-generated numerical functions identified pulmonary edema etiology with an accuracy of 88% when considering the three groups together. When groups were compared as pairs, percentages of correct classification were 91% (group 1 vs. group 2), 93% (group 1 vs. group 3), and 100% (group 2 vs. group 3). Thus, a standardized reading of chest radiographs may be considered a reliable clinical method for identifying pulmonary edema etiology.

Heart Failure↗
PubMed1988

A reexamination of risk factors for ventilatory impairment.

Previous cross-sectional analyses of data from the Tucson Epidemiological Study of Airways Obstructive Diseases have shown significant relationships of ventilatory impairment to a variety of risk factors, including smoking, chronic productive cough, a history of childhood respiratory illnesses, atopy, blood eosinophilia, and serum immunoglobulin E (IgE). In the present report, we reexamine these relationships in subjects 40 to 74 yr of age to determine the effect of excluding known asthmatics who, as a group, have markedly impaired lung function. After exclusion of asthmatics, atopy, eosinophilia, and IgE no longer appear to be significant risk factors for ventilatory impairment, and nonasthmatic nonsmokers show almost no remaining ventilatory impairment. In current smokers, quantitative relationships of FEV1 to pack-years of cigarette consumption and to chronic productive cough are changed little by excluding asthmatics. In nonasthmatic ex-smokers, however, age at quitting smoking adds significantly to prediction of FEV1 after accounting for pack-years. Young ex-smokers closely resemble nonsmokers, but they become increasingly similar to current smokers as their age at quitting increases. A history of respiratory trouble before 16 yr of age continues to appear to increase susceptibility to smoking effects, even after exclusion of asthmatics. But, as in previous studies, the possible bias of preferential recall of childhood illnesses by impaired subjects limits interpretations of this observation. On the other hand, present findings suggest that such factors as atopy, eosinophilia, and elevated serum IgE may well be risk factors for persistent asthma, but they have no relationship to nonasthmatic forms of chronic obstructive pulmonary disease (COPD).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Prevalence of respiratory symptoms in an unpolluted area of northern Italy.

Using a multistage stratified geographic cluster sample of households living in an unpolluted area of Northern Italy (near Venice), we enrolled 3289 inhabitants (aged 8-64 yr) for a longitudinal respiratory study. During the first cross-sectional survey, before the start of operation of a large oil-burning thermoelectric power plant, they completed a standardized administered questionnaire and performed several lung function tests. In the whole sample, dyspnoea grade 1 (11%), chronic cough and chronic phlegm (9%) were the most frequent respiratory symptoms; all the symptoms except dyspnoea were more prevalent in males than in females. Smokers (S) showed higher prevalence rates than ex-smokers (ES) and nonsmokers (NS), especially in males. In both sexes, the frequency of respiratory symptoms increased with increasing smoking as assessed by pack-years. An inverse relationship between prevalence of symptoms and socio-economic status was also observed. All tests of lung function were significantly impaired in S compared with NS in males; single-breath CO diffusing capacity and slope of alveolar plateau but not spirometric indices were significantly impaired in female S compared to female ES and NS. Finally, our prevalence rates were lower than in other epidemiological surveys: this result may be ascribed to the low levels of air pollution measured in the area.

Age Factors↗