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Biomedical subjects

I A Greaves

Publications and source records attributed to I A Greaves.

At least 37 records · Page 2Linked to original sources
PubMed1987

Cotton dust and endotoxin exposure-response relationships in cotton textile workers.

Endotoxin exposure has been implicated in the etiology of lung disease in cotton workers. We investigated this potential relationship in 443 cotton workers from 2 factories in Shanghai and 439 control subjects from a nearby silk mill. A respiratory questionnaire was administered and pre- and postshift forced expiratory volume (FVC) and flow in one second (FEV1) were determined for each worker. Multiple area air samples were analyzed for total elutriated dust concentration (range: 0.15 to 2.5 mg/m3) and endotoxin (range: 0.002 to 0.55 microgram U.S. Reference Endotoxin/m3). The cotton worker population was stratified by current and cumulative dust or endotoxin exposure. Groups were compared for FEV1, FVC, FEV1/FVC%, % change in FEV1 over the shift (delta FEV1%), and prevalences of chronic bronchitis and byssinosis, and linear and logistic regression models were constructed. No dose-response relationships were demonstrated comparing dust concentration to any pulmonary function or symptom variable. A dose-response trend was seen with the current endotoxin level and FEV1, delta FEV1%, and the prevalence of byssinosis and chronic bronchitis, except for the highest exposure level group in which a reversal of the trend was seen. The regression coefficients for current endotoxin exposure were significant (p less than 0.05) in the models for FEV1 and chronic bronchitis but not in the models for delta FEV1% (i.e., acute change in FEV1) or byssinosis prevalence. The coefficient for dust level was never significant in the models.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants, Occupational↗
PubMed1987

Respiratory effects of work in retail food stores. III. Pulmonary function findings.

Findings are reported from a prospective morbidity study which examined the effects on pulmonary function associated with the particulate and gaseous air contaminants to which retail food store workers are exposed. A total of 685 supermarket employees (including meat wrappers, meat cutters and store clerks) performed standard ventilatory function tests [forced expiratory volume in 1 s (FEV1.0) and forced vital capacity (FVC)] during a base-line survey. Those available four years later (305) were resurveyed in a similar manner. A suggestive chronic effect on pulmonary function was shown in those with high cumulative exposures and allergic history. Among those workers who had continuous exposure to air contaminants in settings with "hot-wire" plastic wrap film cutters the annual rates of change in FEV1.0 and FVC were twice as great as the changes found among comparable workers who were not exposed to fumes from wrapping film. Those who switched from the "hot-wire" to the "cool-rod" cutters during the course of the follow-up had intermediate rates of change in lung function.

Adult↗
PubMed1987

Respiratory effects of work in retail food stores. II. Respiratory symptoms.

This study examined the relationships between the prevalence of respiratory tract symptoms and estimates of environmental exposures in retail food stores, in particular exposures to emissions from the cutting of polyvinyl chloride wrap. When respiratory symptoms were compared with a measure of cumulative exposure, there was evidence that the prevalence of symptoms of episodic airway narrowing was higher for workers who had been exposed directly or indirectly to meat wrapping operations independent of a significant association of these symptoms with allergic or asthmatic history. Whether this finding reflects a nonspecific irritant effect or allergic sensitization cannot be determined from these data. No single substance present in the work environment studied has, as yet, been identified as associated with these effects.

Adult↗
PubMed1987

Respiratory effects of work in retail food stores. I. Methodology and exposure assignments.

This study was designed to examine whether retail food store employees have an unusual prevalence or incidence of respiratory symptoms or pulmonary function abnormalities attributable to their work environment. The methodology and development of exposure assignments are presented. Employees from 75 supermarkets (a total of 685 meat cutters, wrappers and store clerks) were tested in a base-line survey, and those still available (305) were resurveyed four years later. Each subject completed a standard questionnaire on job history, health history, cigarette smoking, and respiratory symptoms and also performed five forced expiratory efforts on a standardized spirometer. The major air contaminants were identified including the composition and levels of exposures associated with the different ways of cutting plastic film wrap. A cumulative exposure estimate for each subject was made. Parts II and III of this study present the association of these work environment factors with respiratory symptoms and ventilatory function.

Adult↗
PubMed1986

Estimates of ventilation from body surface measurements in unrestrained subjects.

To make estimates of ventilation from measurements of body surface movements in unrestrained subjects, we measured changes in linear dimensions and cross-sectional areas of the rib cage (RC) and abdomen (AB) of six healthy unrestrained subjects during a variety of maneuvers. RC and AB anteroposterior diameters and abdominal length in the cephalocaudal axis (axial displacement) were measured with magnetometers, and RC and AB cross-sectional areas were measured with a respiratory inductance plethysmograph. Flow was measured at the mouth with a pneumotachograph and integrated electrically to give volume. Volume and body surface measurements were analyzed by multiple linear regression. Addition of the axial measurements to either the anteroposterior dimensions or cross-sectional areas of RC and AB improved estimates of tidal volume in all subjects (P less than 0.01). With measurements of axial displacement and cross-sectional area of the RC and AB, tidal volume could be reliably estimated to within 20% of actual ventilation. We conclude that measurement of axial displacements improves estimates of ventilation in unrestrained subjects.

Abdomen↗
PubMed1985

Chronic airflow obstruction. Evolution of disordered function in cigarette smokers.

Measurements of the mechanical behaviour of the lung, which reflect lung structure, have been used to elucidate the evolution of chronic airflow obstruction in male cigarette smokers and subjects with pulmonary emphysema. The exponent K, from a single exponential function fitted to static pressure-volume data, is an index of lung distensibility directly related to the size of peripheral airspaces. Elastic recoil pressure is inversely related to K. Conductance measured during forced and interrupted deflations of the lungs reflects the dimensions of airways. K increased abnormally with age in smokers suggesting an increase in the airspace size caused by the effects of cigarette smoke which probably acts by intensifying elastase activity in lung tissue. Decreased conductance implying narrowing of airways is found in young smokers, but conductance rises and airways become more distensible in older smokers. A progressive increase in K (with decrease in recoil pressure) and a decrease in conductance are responsible for the advancement of severe airflow obstruction in cigarette smokers.

Adolescent↗
PubMed1985

Large lungs after childhood asthma: a consequence of enlarged airspaces.

The long-term effects of asthma on lung volume were investigated in 18 asthmatic patients during periods of remission from airway obstruction; ten had developed asthma in childhood (before 8 years of age) and eight after the age of 18 years. Subjects whose asthma began in childhood had an increased total lung capacity (TLC) on average; adult-onset asthmatics had normal mean lung volumes. Exponential analysis of static pressure-volume curves in these subjects showed that the childhood-onset asthmatics had lungs of increased distensibility, while adult-onset asthmatics had lungs of normal distensibility. In a further ten adults selected for having had asthma in the past and an increased vital capacity, all had developed asthma in childhood, had lungs of increased distensibility and an increased TLC. Increased distensibility and an increased TLC were closely associated within individuals. The close relationship between distensibility and the size of peripheral air spaces demonstrated in mammalian lungs, suggests that asthma in childhood may increase TLC and distensibility because of an increase in the size of peripheral airspaces.

Adolescent↗
PubMed1984

Selection effects of repeatability criteria applied to lung spirometry.

The potential for introducing bias in studies of pulmonary function by the exclusion of subjects with nonrepeatable measurements was examined in a cohort of Vermont granite workers followed for five years. At each annual survey, a "test failure" was defined as a test in which the two largest forced expiratory volumes in one second (FEV1) differed by more than 200 ml. "Persistent test failure" was defined in terms of 1) the number of test failures for each worker over the six surveys and 2) the difference between the two best efforts at each survey, averaged over all surveys for each worker. The rate of FEV1 loss was estimated for each subject based only on repeatable measurements. It is widespread practice to exclude subjects from analysis who do not perform repeatable lung function tests. The authors found that subjects with persistent test failure were losing FEV1 at a faster rate than subjects without. The results suggest that the application of rigid repeatability criteria may bias epidemiologic findings by the exclusion of many subjects with accelerated loss of lung function.

Adult↗
PubMed1984

Respiratory effects of two types of solder flux used in the electronics industry.

Fumes from solder flux have been shown to cause asthma among solderers in a British electronics factory. In the present study, questionnaires and lung spirometry were administered to 104 U.S. electronics workers (93 women, 11 men) who soldered printed circuit boards. Two types of solder flux were used: 68 subjects had worked only with a rosin-core (colophony) solder; 36 had changed from rosin- to an aqua-core ("phosphorous hexate") solder 15 months before the study. Symptoms of eye, throat, and nose irritation occurred in nearly half of the total group. Lower respiratory tract symptoms, including cough, phlegm production, and wheezing, also occurred with increased frequency, compared with reported rates among a general population. Similar symptom rates were observed among the aqua- and rosin-core groups. That these symptoms were work related was indicated by the subject's improvement on weekends or during vacation periods. On average, lung spirometry performed before starting work on Monday mornings showed no impairment in lung function; over the course of the work day there were small decrements in the forced expiratory volume at 1 s (mean, -21 +/- 11 [SD] ml) and forced vital capacity (-30 +/- 145 ml), but these decrements were unrelated to the individual amounts of solder used during the same period. Among the white female workers (N = 83), several multivariate analyses indicated that an increase in the amount of soldering had a beneficial effect on lung function, particularly among those who currently smoked. This paradox probably resulted from a "healthy worker effect" resulting from some individuals with lower than average lung function who left the industry early in the course of their employment.

Adult↗
PubMed1983

Alveolar size as a determinant of pulmonary distensibility in mammalian lungs.

Pulmonary distensibility depends on surface tension and tissue elastic forces, but the relative contribution of each to total lung recoil remains incompletely defined. By applying an exponential analysis to static pressure-volume curves obtained from the excised lungs of cats, dogs, and rats with air and saline filling, the exponential constant K (an index of lung distensibility) was related to the mean linear intercept Lm (a morphometric estimate of the mean size of peripheral air spaces at maximal inflation). K for air filling (Ka) was unrelated to K for saline filling (Ks), and Ks was unrelated to Lm, but similar highly significant regressions of Ka on Lm were found in each species, and the common regression was similar to that described previously for human lungs. Approximately 86% of the variance in lung distensibility (Ka) within and between species was explained by Lm. Because Lm determines the size of air spaces, and therefore the alveolar surface-to-volume ratio, the findings indicate that the density of surface forces is the major determinant of lung distensibility in the air-filled state.

Animals↗
PubMed1983

Byssinosis: a role for public health in the face of scientific uncertainty.

Byssinosis, a lung disease caused by cotton dust, has been the subject of recent controversy. Debates over the nature of the disease, possible interactions with cigarette smoking, and the proposed reevaluation of the cotton dust standard by the Occupational Safety and Health Administration have tended to overlook the plight of affected workers and to obscure the most effective means for preventing the disease. The present lack of definitive information is no reason for inaction, nor for depriving disabled workers of adequate financial compensation. In this respect, byssinosis is no different from other public health hazards for which action must often be taken on the basis of incomplete evidence.

Byssinosis↗
PubMed1981

A possible role for corticosteroids in the treatment of influenzal pneumonia.

A 52-year-old woman with severe influenzal pneumonia developed increasing hypoxaemia on the sixth and seventh hospital days. Hydrocortisone (250 mg intravenously) was given on the seventh day and the arterial oxygen tension increased within two hours. Clinical improvement continued with further steroid therapy. Corticosteroids were ceased after three weeks, but were recommenced three weeks later when the vital capacity (VC) remained about half of the expected normal value. Although the VC had not altered for two weeks, the reintroduction of a steroid was followed within a week by an increase in VC which continued for a further eight weeks. Sequential measurements of the mechanical properties of the lungs during this recovery period showed that atelectatic areas had reinflated. Instability of lung units accompanied the increase in lung volume, suggesting a partial deficiency of surfactant in the recruited units. Eighteen months after presentation, lung volumes remained mildly decreased but the elastic behaviour, airway conductance, and gas exchanging properties of the lungs were normal. Although some alveoli had been permanently lost, there was no evidence of diffuse lung fibrosis and the remaining lung units functioned normally.

Female↗
PubMed1980

Elastic behavior and structure of normal and emphysematous lungs post mortem.

To examine the relationship between lung structure and function, static deflation pressure-volume curves were measured post mortem in 14 normal and 7 emphysematous lungs, and the results were compared to morphometric measurements of lung. Elastic behavior was described satisfactorily by an exponential function: V = A -Be-KP, where V is lung volume, P is static recoil pressure, and A, B, and K are constants. The constant K, an index of pulmonary elasticity, was closely related to a morphometric measurement of mean alveolar size. In normal lungs the decrease in pulmonary elasticity with age was quantified by an increase in K. When emphysema was present, K was invariably increased by more than 2 SD above the mean predicted value for age, reflecting the abnormally increased distensibility of alveoli in this disorder. The present findings indicate that a similar analysis of pressure-volume measurements obtained during life will reliably detect the presence of pulmonary emphysema in patients with chronic airflow limitation.

Adolescent↗