Biomedical subjects

S Vedal

Publications and source records attributed to S Vedal.

60 records · Page 4Linked to original sources

PubMedDate not supplied

Immediate skin reactivity and its relationship to age, sex, smoking, and occupational exposure.

To evaluate potential predictors of atopy, 3353 workers from various occupations were classified according to airborne exposures into three groups: (1) 1213 control workers with no measurable exposures, (2) 815 workers with gas and fume exposure, and (3) 1325 workers with organic dust exposure. Atopic status was determined by prick skin testing with common allergens. Workers exposed to organic dusts had a lower prevalence of skin test reactivity than either controls or gas- and fume-exposed workers. Skin test reactivity also decreased with age and was higher in nonwhite workers compared to white workers. No difference in skin test reactivity was seen between female and male workers, nor between smoking and nonsmoking workers. A logistic regression analysis that controlled for the correlation between the predictive factors confirmed the results of the crude analyses. It is suggested that atopic workers exposed to organic dusts might selectively leave the industry.

Adolescent↗

PubMedDate not supplied

Symptoms and pulmonary function in western red cedar workers related to duration of employment and dust exposure.

Measurements of total dust concentration were made in a western red cedar sawmill that employed 701 workers. Both area sampling and personal sampling of total dust were done over an 8-hr shift corresponding to job descriptions and locations to assign each worker an exposure level. A total of 652 (93%) of the workers completed a respiratory-occupational questionnaire and performed spirometry, of whom 334 were assigned an exposure level. Dust exposure ranged from undetectable to 6.0 mg/m3 with a median exposure level of 0.2 mg/m3. Only 10% of the workers with an assigned exposure level were exposed to more than 1.0 mg/m3. Work-related asthma, defined as symptoms of asthma which improved on days off work, was reported by 52 workers (8.0%) and was more prevalent after 10 or more yr of employment. Chronic cough, dyspnea, persistent wheeze, and physician-diagnosed asthma were unrelated to either work duration or exposure. Levels of forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV1.0) were lower with dust concentrations greater than 2.0 mg/m3, controlling for age and smoking; maximum mid-expiratory flow rate (FEF25-75%) and FEV1.0/FVC were unrelated to dust exposure concentration. Work-related symptoms of eye irritation were seen more commonly with exposure to dust concentrations of 3.0 mg/m3 or more. It is concluded that symptoms of work-related asthma in red cedar workers are more common after 10 yr of exposure, and that levels of pulmonary function are lower with higher wood dust exposures.

Adult↗

PubMedDate not supplied

Health effects of air pollution due to coal combustion in the Chestnut Ridge region of Pennsylvania: cross-section survey of children.

A cross-sectional study of 4,071 children aged 6-11 yr of age from a rural region of Western Pennsylvania was conducted in spring of 1979. Standardized children's questionnaires were distributed to the parents and returned by the children to school, where spirometry was performed. The region was divided into low-, moderate-, and high-pollution areas on the basis of the 1974-1978, 3-hr, 24-hr, and annual averages for sulfur dioxide (SO2). Seventeen monitoring stations in the region and a triangulation procedure were used to estimate centroid levels in each geographic residence area. After adjusting the respiratory symptom response outcomes and the pulmonary function levels for known predictors, no significant association was noted for level of SO2. However, the highest exposure categories were only slightly above the present annual and 24-hr National Air Quality Standards for SO2. We conclude that at levels of exposure to which these children were exposed, only by study of potentially sensitive subsets or measures of acute response would it be possible to detect respiratory outcomes associated with ambient air pollution.

Air Pollutants↗

PubMedDate not supplied

Summarizing methacholine bronchoprovocation data in epidemiological surveys.

We have performed bronchoprovocation tests with methacholine in 41 patients with asthma due to Western red cedar dust and in 56 office-workers without known respiratory illness. Our purpose was to define a summary statistic for useful bronchial hyperresponsiveness in epidemiologic surveys. We found a significant linear relationship between the concentration of methacholine and the FEV1 response. We noted, in addition, a positive relation between the rate of the FEV1 response per concentration and the level of FEV1. We conclude that a linear dose-response slope, which can be calculated for each individual, provides a comprehensive summary of methacholine bronchoprovocation tests and is useful in epidemiologic surveys.

Adult↗

PubMedDate not supplied

Absence of day to day variation in lymphocyte subpopulations in healthy humans.

Lymphocyte subpopulations were determined by indirect immunofluorescence using monoclonal antibodies T11, T4, T8 and B1 on three different days in a group of thirteen normal subjects. Although there was considerable intersubject variation, the percentages of lymphocyte subpopulations as well as absolute numbers did not differ within the same subject over the three days tested, showing that lymphocyte subpopulation proportions and absolute numbers are stable characteristics of the healthy subject.

Adult↗

PubMedDate not supplied

False positive rates of multiple pulmonary function tests in healthy subjects.

Spirometry, diffusing capacity and lung volume tests were performed on 251 healthy, nonsmoking volunteers in order to determine the rate of false positive results of multiple pulmonary function tests. Each test had an approximately 5% false positive rate, defined here as the percentage of normal subjects classified as abnormal by the tests. The percentage of subjects with at least one abnormal test rose substantially as the number of tests performed increased. When simple spirometry (FVC, FEV1, FEV1/FVC) was performed, 10% had at least one abnormal test; this rose to 24% when a complete battery of 14 tests was performed.

False Positive Reactions↗