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Biomedical subjects

P Corey

Publications and source records attributed to P Corey.

At least 55 records · Page 3Linked to original sources
PubMed1985

Severity of asthma in skin test-negative and skin test-positive patients.

The standardized records of 144 asthmatic patients have been analyzed to determine whether the severity of their condition was correlated with the presence or absence of positive intradermal skin test reactions to a panel of seven allergen extracts (dust, feathers, Alternaria, Hormodendrum, mixed tree pollen, mixed grass pollen, and ragweed pollen). The skin tests were totally negative in 71 of the subjects, whereas in 73 subjects there was a strongly positive response to two or more allergens. The skin test-negative patients were older than the skin test-positive ones and had a shorter duration as well as a later onset of asthma. Also, they had lower serum-IgE levels and a lower frequency of a family history of atopic disease. Moreover, the skin test-negative group lost more time from their normal activities, required more visits to their doctor as a result of asthma, and were more frequently treated with oral corticosteroids. They additionally had greater air trapping on pulmonary function tests. However, when the groups were adjusted for the discordance in their age and duration of asthma, they tended to converge in the level of the variables that described the severity of their asthma. Thus the severity of asthma was found to be relatively similar in skin test-negative and skin test-positive patients.

Adult↗
PubMed1985

Electrocardiographic estimate of peak systolic pressure gradient in children with aortic stenosis.

In children with congenital aortic stenosis a modified mapping system was created to explore the electrocardiographic potentials on the chest surface from the left sternal edge (direct anterior), left axillary line (direct lateral) and midchest (45 degrees anterior to the lateral lead) in the third through the seventh intercostal spaces. Potentials were normalized according to chest size based on elliptical and cylindrical models of the chest with the heart at the center. The unadjusted and adjusted potentials were correlated with the peak systolic gradients across the left ventricular outflow tract and equations to predict the gradients were derived by stepwise multiple regression analysis. The best equation was: Gradient = -15.0 +(3.845 X MCT 4) +(0.474 X CD X LSS 3) + (0.138 X CD X MCS 3) where MCT 4 = T wave amplitude in the lead in the fourth interspace in the midclavicular line CD = AP chest diameter in cm LSS 3 = S wave amplitude in the lead in the third interspace at the left sternal border MCS 3 = S wave amplitude in the lead in the third interspace in the midclavicular line (R = 0.84, SEE = 24.3) There are areas on the chest surface that are unexplored by standard electrocardiography. The electrocardiographic potentials from these areas, when normalized for chest size, yield better estimates of transaortic gradients than previous estimates from the routine electrocardiogram.

Adolescent↗
PubMed1985

Evaluation of respiratory variables in smelter and control workers before and during a shutdown period.

Thirty-six smelter workers examined in this pilot study were found to have a higher prevalence of cough and dyspnea and lower baseline lung function than did 31 controls. They also experienced decreases in forced vital capacity (FVC) and forced expiratory volume in 1s (FEV1) over the workweek while the controls did not. Baseline airflow rates and change in FVC and FEV1 over the workweek varied with levels of sulfur dioxide and particulates. Twenty-three smelter workers and 21 controls were seen on a second occasion, six months into an extended shutdown. The smelter workers continued to have a higher prevalence of cough and dyspnea and lower baseline lung function than the controls. There was, however, a slight increase in lung function in both the exposed workers and the controls during the shutdown. The results suggest that smelter workers may develop both acute and chronic work-related pulmonary effects and that the chronic effects may be nonreversible.

Adult↗
PubMed1985

Prostaglandin inhibition and the rate of recovery after arthroscopic meniscectomy. A randomised double-blind prospective study.

In a double-blind, randomised, prospective study of 139 patients undergoing arthroscopic meniscectomy, those receiving a prostaglandin inhibitor (naproxen sodium) had significantly less pain, less synovitis and less effusion. They had significantly more rapid return of movement and of quadriceps function; their return to work and to sport also was significantly faster. It is recommended that, provided there are no contraindications, a prostaglandin inhibitor should be used after arthroscopic procedures.

Adolescent↗
PubMed1985

Longitudinal study of grain elevator and control workers with demonstration of healthy worker effect.

Changes in the respiratory symptoms and pulmonary function of 441 grain elevator workers and a control group of 180 civic workers during a three-year period were compared. The grain handlers who left their jobs during the interval between the first and second surveys were found to have shown a significantly higher prevalence of cough and shortness of breath at the beginning of the study period than those who remained employed; this difference was not observed among the civic workers. The grain and civic workers who were examined on both occasions showed similar longitudinal changes in their symptoms and pulmonary function. Nevertheless, the results of this study are biased by the healthy worker effect among the grain handlers.

Age Factors↗
PubMed1984

Changes in respiratory variables of grain handlers and civic workers during their initial months of employment.

The health effects of employment as a grain handler were studied by examining workers on two occasions, firstly, immediately before or soon after they were hired and again about two and a half months after they were employed. Over this time there was a substantial increase in the prevalence of cough, sputum, and eye irritation, accompanied by small pulmonary function changes suggestive of a restrictive ventilatory defect. No comparable changes in symptoms were observed over a similar number of months in grain handlers employed for an average of nine years or in control workers consisting of newly hired or long term civic outside labourers. The long term grain handlers, however, developed a similar change in their pulmonary function. These findings indicate the occurrence of a change in the health of grain elevator workers after a relatively brief duration of employment.

Adolescent↗
PubMed1983

Variables of pulmonary allergy and inflammation in grain elevator workers.

The purpose of this study was to examine possible mechanisms of the obstructive and restrictive ventilatory defects of grain elevator workers. We found that grain handlers whose skin tests were positive to grain or fungal antigens had no excess of respiratory symptoms or pulmonary function abnormalities. Also, those having a possible work-related respiratory problem showed no response to inhalation challenge tests with grain dust extract. In addition, grain handlers exhibited neither an increase in positive serum precipitin tests with fungal antigens nor abnormal serum levels of C3 and C4, C-reactive protein, rheumatoid factor or antinuclear factor. However, their serum a1-antitrypsin level was elevated. The latter finding may be indicative of a pulmonary inflammatory process, but we have found no clear indication of a type 1 or 3 allergic state in grain elevator workers.

Adult↗
PubMed1982

Grain elevator workers show work-related pulmonary function changes and dose-effect relationships with dust exposure.

The purpose of this study was to determine whether grain handlers underwent work-related changes in their pulmonary function and, if so, to examine the dose-effect relationships with dust exposure. The pulmonary function of grain handlers was measured at the beginning and end of work shifts over a period of one week, during which their exposure to dust was measured daily. The results showed changes indicative of a within-day obstructive change, in addition to a small restrictive defect occurring over the course of a week. Civic outside labourers who were examined as a control group showed a similar within-week obstructive change without any associated restriction of lung volume. The data on the grain handlers were also used to examine the dose-effect relationships of dust exposure, both on baseline pulmonary function and on within-day changes in these measurements. The baseline flow rates of workers who did not wear a mask were found to vary inversely with their average exposure to respirable dust. In addition, the flow rates underwent a within-day decrease that varied directly with their corresponding exposure to respirable dust and was unrelated to mask wearing. The median of the slopes for this relationship indicated that 50% of the subjects had a decrease of at least 923 ml/s in the value of their Vmax50%VC for each 1 mg/m3 increase in the concentration of respirable dust. Non-respirable dust did not have a measurable effect either on the baseline or the within-day changes in pulmonary function. The acute changes were unaffected by age, duration of employment, or extent of smoking.

Adult↗
PubMed1982

Sweat composition in exercise and in heat.

Sweat samples were collected from the forearms of eight male volunteers using light gauze pads applied for 20-min periods. Preliminary trials indicated that this technique yielded realistic figures for both sweat volume and sweat composition. Tests were conducted under three conditions: a) outdoor exercise, cool environment; b) indoor exercise, normal room temperatures; and c) sauna exposure. In all environments, proximal forearm samples indicated a larger sweat secretion than distal forearm or hand samples. [Mg2+] decreased as sweat flow increased, but after allowance for interindividual differences of sweat volume, [Na+], [K+], [Ca2+], and [Cl-] were independent of sweat flow rates. The differential effect of sweat flow suggests active regulation rather than contamination. Interindividual differences of sweat composition could not be explained in terms of differences in personal fitness. Sauna bathing yielded sweat with a higher [Mg2+] and [Ca2+] content than did exercise; however, [Na+], [K+], and [Cl-] were similar for the three experimental conditions. Again, the data are best explained in terms of an active regulation of sweat composition. Total ionic losses do not seem sufficient to deplete body mineral reserves unless many days of training are undertaken in a hot climate.

Adult↗
PubMed1981

Exercise compliance and the prevention of a recurrence of myocardial infarction.

Exercise compliance (three exercise sessions per week) has been shown to have a favorable effect upon prognosis (P less than 0.001) in 610 "post-coronary" patients followed for an average of 36.5 months. This cannot be explained entirely by mutual correlation of the data with other health habits (as indicated by smoking behavior) or disease severity (as indicated by angina, exercise-induced ST-segmental depression, cardiac enlargement, or ventricular aneurysm). Stratification of the data shows that in almost all categories of subject, sustained physical activity is associated with a five-fold improvement in the odds ratio for both fatal and non-fatal recurrences of the infarction.

Exercise Therapy↗
PubMed1981

Fitness program participation: its effect on worker performance.

The effects of an employee fitness program upon absenteeism and productivity were investigated in a controlled trial involving two large offices. During the six-month experimental program, the test company developed substantial gains of fitness. However self-reports and supervisor evaluations showed small and relatively similar gains of productivity, with reduction of absenteeism at both test and control companies. Further studies on a large scale are warranted. The presently observed changes probably reflect (1) sample attenuation, (2) seasonal trends, and (3) a "Hawthorne" effect. If the last factor is substantiated, employee fitness programs may be of economic interest, despite the nonspecific nature of the resultant gains in productivity.

Adult↗
PubMed1980

Smoking, dust exposure, and serum alpha 1-antitrypsin.

The relationships of smoking and dust exposure to serum alpha 1-antitrypsin concentrations were studied in 1,131 male workers who were PiM phenotypes and who were employed in 4 different environments. In each work group, current smokers had higher concentrations than nonsmokers or ex-smokers. Among current smokers, concentrations were highest in those who smoked the most and for the longest time. Within the smoking categories the concentrations in most instances were greatest in workers exposed to the greatest dust concentrations. A significant positive relationship with duration of employment was found only in 1 work group. The independent effects of smoking and dust exposure persisted when the analysis was repeated using only nonatopic workers who were free of chest symptoms. Although both the biologic significance of these variations and the underlying mechanisms require clarification, the findings suggest that extrinsic factors, such as smoking and industrial dust exposure, may influence serum alpha 1-antitrypsin concentrations.

Adult↗
PubMed1979

Comparison of respiratory variables in grain elevator workers and civic outside workers of Thunder Bay, Canada.

We compared respiratory variables in 441 grain elevator workers with 180 civic outside laborers in Thunder Bay. The grain handlers had a lower frequency of both positive skin reactions to pollens and molds and a family history of asthma, which suggests that they may have been self-selected for a decreased tendency to develop allergic respiratory disease. There was a higher frequency of cough and rales and a small decrease in forced vital capacity and forced expiratory volume in one sec among the grain handlers, as compared to the civic workers matched for smoking. However, these differences between grain and nongrain workers were small in comparison to those between smokers and nonsmokers. There was no clear indication of a worsening of respiratory functions that could be attributed specifically to duration of employment as a grain elevator worker.

Adult↗
PubMed1979

Some factors affecting accuracy of Canadian Home Fitness Test scores.

Factors affecting the accuracy of Canadian Home Fitness Test scores have been evaluated in male and female office workers. At a first attempt, the typical subject underestimates his 10 sec post-exercise pulse count by 1 beat, with a superimposed probable error of 2 beats. However, the modest experience of pulse counting gained in an employee fitness programme corrects the systematic error, while the probable random error is reduced to approximately 8 beats/min. Taking account also of variations in the fficiency of stepping, the probable error of an Astrand prediction of V O2(max) is approximately 10.3%. Comparison with directly measured values in a subsample of 22 men shows an actual random discrepancy of 9.5%, plus a systematic error of approximately 19% due to an increase of heart rate with anticipation of the maximum test. The Jetté prediction formula has a random discrepancy of approximately 8%, plus a systematic error of approximately 10.6%. Assuming the latter can be corrected by evaluation of a larger population, the fitness scores should give most people an indication of both their initial fitness and responses to a training regimen.

Adult↗
PubMed1978

Pi phenotypes and the prevalence of chest symptoms and lung function abnormalities in workers employed in dusty industris.

Epidemiologic surveys were carried out on 1,138 white men employed in sawmills and grain elevator terminals in British Columbia. In addition to the administration of an occupational-health questionnaire and spirometry, Pi phenotype and the concentration of serum alpha1-antitrypsin were determined. Most of the workers (88.8 per cent) had the Pi M phenotype, whereas 8.0 per cent had the MS phenotype, and 2.7 per cent had the MZ phenotype. Very few workers (0.4 per cent) had other phenotypes. No differences were found among the 3 major phenotypes in the prevalence of chest symptoms and lung function abnormalities, even among cigarette smokers. These findings did not indicate that workers have the MZ phenotype with intermediate alpha-1-antitrypsin deficiency are particularly susceptible to the development of chronic obstructive lung disease under the conditions prevailing in these industries.

Adult↗