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Biomedical subjects

C A Soutar

Publications and source records attributed to C A Soutar.

At least 19 recordsLinked to original sources
PubMed1992

Immune responses to colophony, an agent causing occupational asthma.

BACKGROUND: Inhalation of fumes from heated colophony (pine resin) is a recognised cause of occupational asthma, although the mechanisms by which colophony produces symptoms are unclear and specific immune responses to colophony have not been reported in sensitised workers. A study was carried out to determine whether colophony is antigenic. METHODS: The immune responses to colophony were studied in C57BL/6 mice and Dunkin Hartley guinea pigs after intraperitoneal injection of colophony conjugated to bovine serum albumin (BSA) or human IgG by a mixed anhydride procedure. Colophony and dinitrofluorobenzene were also compared in an assay of dermal sensitisation. RESULTS: Mice immunised with the colophony conjugates produced antibodies which recognised conjugates of both BSA and human IgG irrespective of which had been used as the immunogen. Solutions of unconjugated colophony inhibited the binding of antibodies to the BSA-colophony and BSA-abietic acid conjugates, confirming that the antibodies recognised one or more components in the colophony. Portuguese colophony also abrogated the antigen binding of serum from guinea pigs immunised with the BSA-colophony conjugate. Spleen cells from immunised mice proliferated in the presence of the conjugates. Although there was some cross reactivity in these responses, it was not as marked as in the antibody assays. Unconjugated colophony failed to induce an immune response when injected intraperitoneally with adjuvant. Skin sensitisation could not be induced in mice by topical application, or by subcutaneous or intradermal injection of unconjugated colophony. CONCLUSIONS: Colophony components have the potential to act as haptens and an immune component could be involved in the pathogenesis of occupational asthma in workers exposed to colophony. Colophony is not readily immunogenic unless conjugated ex vivo to proteins.

Animals↗
PubMed1991

The characteristics of respiratory ill health of wool textile workers.

The relations of lung function and chest radiographic appearances with exposure to inspirable dust were examined in 634 workers in five wool textile mills in west Yorkshire, randomly selected to represent fully the range of current exposures to wool mill dust. Most of these workers could be categorised into three large sex and ethnic groups; European men, Asian men, and Asian women. Exposures to inspirable dust had been measured at a previous survey and time spent in current job, and in the industry were used as surrogates for lifetime cumulative exposures. Chest radiographs were interpreted on the International Labour Office (ILO) scale by three medically qualified readers, and the results combined. Profusions of small opacities of 0/1 on the ILO scale, or greater, were present in only 6% of the population, and were not positively associated with current exposure to wool mill dust, or duration of exposure. In general, statistically significant relations between exposure and lung function indices were not found, with the exception of an inverse relation between the forced expiratory volume/forced vital capacity ratio and dust concentration in European women. A suggestive but not statistically significant inverse relation between FVC and current dust concentration was seen in Asian men. Substantial differences were found between mills in mean values of lung function variables after adjustment for other factors but these were not apparently related to the differences in dust concentrations between these mills. Dyeworkers and wool scourers (mostly European men in relatively dust free jobs) on average experienced an FEV1 251 ml lower than other workers when age, height, smoking habits, and occupational factors had been taken into account. Twenty four per cent of the workforce responded to intracutaneous application of one or more common allergens (weal diameter at least 4 mm), only 12 (7.9%) of these responding to wool extracts. Atopic subjects did not appear to have an increased susceptibility to the effects of inspirable wool dust on lung function. These studies suggest that exposure to wool mill dust may cause functional impairment in some workers but there is little indication from these data of frequent or severe dust related functional deficits. More detailed estimates of cumulative dust exposure by reconstruction of exposure histories might clarify associations between exposure to dust and lung function. These chest radiographic findings provide no evidence that exposure to wool mill dust is related to lung fibrosis.

Adult↗
PubMed1990

Inflammation in the lungs of rats after deposition of dust collected from the air of wool mills: the role of epithelial injury and complement activation.

In a previous study assessing respiratory symptoms in individuals employed in wool textile mills in the north of England relations between symptoms of chronic bronchitis, breathlessness and wheeze, and rhinitis and current exposure to airborne mass concentration of dust were shown. As preliminary steps in defining the potential hazard associated with dust from the air of wool mills the ability of inspirable dust, collected from the air of wool textile mills, to cause inflammation when injected into the lungs of rats was determined. Dusts were collected from the beginning of wool processing (opening) in one factory and from the middle (combing) and late (backwinding) stages of the process in two other factories. Ability of the dusts to cause inflammation was assessed by instillation into the lungs of rats followed by bronchoalveolar lavage. All the dusts caused some inflammation which peaked on day 1 and did not persist beyond one week. A distinctive aggregation response of mononuclear cells in the lavage, however, had a different time course, peaking at day 7. An attempt was made to determine how the wool mill dusts caused inflammation and experiments showed that the dusts themselves had no inherent chemotactic activity but that they did have a pronounced ability to generate chemotaxins in serum and so could activate complement in lung fluid. In addition, dust collected from ledges in the mills had the ability to injure epithelial cells in vitro which could also contribute to inflammation. A role for endotoxin in the inflammatory activity of the dusts was not discounted and a leachate of the dust had the ability to cause inflammation when injected into the lungs of rats. Wool mill dust is likely to be a complex mixture of materials and these experiments represent a preliminary approach to understanding the biological activity of the whole unfractionated dust and further studies are in progress to define more accurately the toxic material(s) in the dust.

Animals↗
PubMed1988

Respiratory and allergic symptoms in wool textile workers.

An epidemiological study of 2153 workers in 15 West Yorkshire wool textile mills was conducted to determine relations between respiratory symptoms and exposure to inspirable wool mill dust. A questionnaire designed to elicit all the common respiratory symptoms was developed and tested, and administered to all workers willing to participate (85%). It was translated and administered in Urdu for the 385 workers from Pakistan whose English was not fluent. Symptoms investigated included cough and phlegm, wheezing and chest tightness, breathlessness and its variability, rhinitis, conjunctivitis, chills, nosebleeds, and chest illnesses. Additional questions were asked, where appropriate, about the times of day, days of the week, seasons, and places that the symptoms were worse or better than normal. An environmental survey was carried out at each mill, which included 629 measurements of inspirable dust, enabling estimates to be made of the airborne concentrations of inspirable dust usually experienced by each member of the workforce under current conditions. Overall symptom prevalences were: persistent cough and phlegm, 9%; wheeze, 31%; breathlessness on walking with others on level ground, 10%; persistent rhinitis, 18%; persistent conjunctivitis, 10%; persistent chills, 2%; ten or more nosebleeds a year, 2%; and three or more chest illnesses in past three years, 5%. After allowing for the effects of age, sex, smoking habit, and ethnic group, cough and phlegm, wheeze, breathlessness, rhinitis, conjunctivitis, and nosebleeds were found to be more frequent in those exposed to higher than to lower concentrations of dust. In some experiencing high concentrations (blenders and carpet yarn backwinders) cough and phlegm, wheeze, rhinitis, and conjunctivitis were related to the years worked in such jobs. Relative risks of each symptom in relation to inspirable dust concentrations were calculated by means of a logistic regression analysis. At concentrations of 10 mg/m3, the current United Kingdom standard for nuisance dusts, the risk of cough and phlegm relative to that of an unexposed worker was 1.37, that of wheeze 1.40, breathlessness 1.48, rhinitis 1.24, and conjunctivitis 1.70. Since some of these symptoms may be associated with functional impairment of the lungs, further studies of selected workers are being carried out to estimate the functional effects of exposure to dust in wool textile mills.

Adolescent↗
PubMed1988

Assessment of variability of exercise tolerance limited by breathlessness.

A sequence of questions was designed to quantify the within subject variation of exercise tolerance limited by breathlessness, to serve as a guide to variation in airflow limitation for epidemiological purposes. The questions seek answers about breathlessness in relation to various levels of attempted activity when the subjects are at their best and at their worst. The difference between exercise tolerance at best and exercise tolerance at worst (variation in exercise tolerance) was expressed on a scale ranging from 0 (no variation) to 6 (greatest variation). The effectiveness of these questions has been assessed in 68 patients with airflow limitation attending a chest clinic, by comparing the results with variation in peak expiratory flow rate (PEF). Variation in PEF was expressed as the standard deviation of the first 24 PEF recordings from each patient (equivalent to four days' recordings). There was a highly significant relation between the measure of variation in exercise tolerance obtained from the questionnaire and PEF variation, though each point on the scale of variation in exercise tolerance covered a wide range of variation in PEF. The questions give some guide to the variation in airflow limitation and in combination with other questions may be helpful in epidemiological studies.

Adolescent↗
PubMed1986

Epidemiologic study of back pain in miners and office workers.

Cross-sectional studies of miners at a Scottish colliery and workers in an administrative office were done to investigate the prevalence of back pain among them and to compare prevalence of pain with type of job. Sixty-two percent of the invited miners and 71% of the office workers participated. More than two thirds of the miners and more than one half of the office workers who participated reported back pain at some time in their lives. No relationship was detected between present job and back pain among the miners, except for a suggestion that recent first attacks of pain were more common in face workers and underground transport workers than in other men. These results confirm that back pain is a common problem in both miners and office workers.

Adult↗
PubMed1986

Quantitative relations between exposure to respirable coalmine dust and coalworkers' simple pneumoconiosis in men who have worked as miners but have left the coal industry.

Present estimates of the quantitative relations between exposure to mixed respirable coalmine dust and risk of developing coalworkes' simple pneumoconiosis are based on studies of working miners. These studies did not include men who had been miners but had left the coal industry, and it was not known whether the estimates of risk were also appropriate for these men. The results are reported of a study in which the dust/disease relations in men who have been miners but have left the industry have been compared with those in men who have remained in it. A sample of 17738 men who were first examined when working in 24 British collieries in the 1950s has been followed up about 22 years later. It was possible to examine 61% of the survivors, 44% of the original sample. Simple pneumoconiosis was more frequent among men (particularly older men) who had left the industry than among those who had stayed in it. A detailed analysis did not show any systematic or statistically significant difference between men who stayed and men who left in the quantitative relations between dust exposure and simple pneumoconiosis. Present estimates of risk of simple pneumoconiosis in relation to exposure to mixed respirable dust in working miners adequately describe the relation found in men who have been miners but have left the industry.

Adult↗
PubMed1986

Can exposure to coalmine dust cause a severe impairment of lung function?

It is well recognised that exposure to respirable coalmine dust causes a reduction in lung function but it has not been clear whether the impairment of function is sufficient to cause disability, unless progressive massive fibrosis occurs. From a study of 4059 men without progressive massive fibrosis who worked in the coal industry for at least ten years from the 1950s, and who were followed up and re-examined medically more than 20 years later, a subgroup was selected using criteria intended to favour those who may have suffered greater than average effects of dust exposure. These 199 men had left the coal industry before normal retiral age, had taken other jobs, and had reported symptoms of chronic bronchitis at follow up. The inverse relation between dust exposure and FEV1 among these 199 men was much more severe than the average effects previously shown among more representative groups of coalminers. The effect of exposure to respirable dust was estimated conservatively as an impairment of about 2 ml FEV1 per unit of dust exposure (gh/m3). The estimated effect among ex-smokers was more severe. These compare with a previous estimate, based on a less selected population, of 0.6 ml FEV1 per gh/m3. The new estimate in this group of 199 men corresponds to an average loss of 600 ml FEV1 in response to a moderately high dust exposure to 300 gh/m3, with correspondingly higher losses in the ex-smokers. These findings show that among a group of men intentionally selected to include those who may have suffered greater than average effects of dust exposure, the relation between exposure and FEV1 is consistent with the view that in some men even moderately high exposure to dust causes severe impairment of lung function.

Coal Mining↗
PubMed1986

Respiratory ill health among coal miners and telecommunication workers in south Wales.

As part of a large cross sectional epidemiological study of respiratory disease in coalminers, the respiratory health of miners in one colliery in south Wales has been compared with the health of nearby telecommunication (telecom) workers. The studies were carried out in 1981 and 1982. The answers to questionnaires on respiratory symptoms and results of lung spirometry indicate a much greater frequency of respiratory ill health among the miners than the telecom workers. The frequency of symptoms of chronic bronchitis among the current employees was 31% in the miners and 5% in the telecom workers, and these symptoms were reported as frequently by younger as by older miners. Reports of other respiratory symptoms showed similarly large differences between current miners and telecom workers. These differences were seen both within non-smoking and smoking groups. Comparisons of FEV1 with predicted values (several different predictions were used) confirmed that the differences in reported symptoms were accompanied by differences in lung function; of the order of 20% of current miners had an FEV1 less than 80% of predicted compared with 10% of current telecom workers. The excess of respiratory disease shown among these miners is not necessarily a consequence of the dust concentrations currently experienced underground, nor is the colliery necessarily representative of the coal industry generally. The findings, however, indicate the continued need for measures to improve the respiratory health of these men.

Adult↗
PubMed1986

Relation between dust exposure and lung function in miners and ex-miners.

A sample of men working in the British coal industry in the 1950s has been followed up and examined 22 years later. The relations between lung function and individual cumulative exposure to respirable dust have been studied in 1867 men who were still working in the industry at the time of follow up and 2192 men who had left. Levels of forced expired volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio at follow up were found to be inversely related to exposure to respirable dust after allowing for other factors, even in men without pneumoconiosis. The magnitude of this estimated effect was equivalent to a loss of 228 ml FEV1 in response to an exposure of 300 gh/m3, a moderately high exposure for this group. Ex-miners aged under 65 had worse lung function than miners on average, suggesting that ill health had encouraged some of these men to leave the industry. Whereas a more severe response to dust exposure among ex-miners under 65 was suggested, this difference could easily have arisen by chance. The presence of symptoms of chronic bronchitis was associated with reduced levels of lung function, however, and, additionally, ex-miners under 65 with chronic bronchitis showed a more severe response of the FVC to dust exposure than miners without these symptoms. Among these ex-miners with chronic bronchitis a small group of men who had taken other jobs showed a much more severe effect of dust exposure on their lung function than the average, likely in heavily exposed men to contribute importantly to disability. Men in this group who had given up smoking showed and even more severe effect of dust exposure, equivalent to a loss of 940 ml FEV1 in response to an exposure of 300 gh/m3. These results indicate that exposure to respirable dust can occasionally cause severe respiratory impairment in the absence of progressive massive fibrosis. Dust exposure was related to a parallel reduction of FEV1 and FVC, implying that the pathology of dust induced lung damage differs form that induced by smoking. This pattern of abnormality was shown by some non-smokers, whereas smokers and ex-smokers apparently severely affected by dust showed a classic obstructive pattern of abnormality with pronounced reduction of the FEV1/FVC ratio.

Aged↗
PubMed1985

Progressive massive fibrosis and simple pneumoconiosis in ex-miners.

A group of 17 738 working miners, medically examined during 1953-8, were followed up from 1974 to 1980. Of the 7118 men re-examined, 2547 were still working miners and 4526 had left the industry (45 were of unrecorded status). The incidence of progressive massive fibrosis (PMF) over an average follow up period of 22 years among men who had remained in the industry was 27 per 1000, but 94 per 1000 among men who had left. This difference was only partly related to the difference in age between the groups; for men without simple pneumoconiosis at the start of the period, and for similar age groups (45-64), the attack rate in miners was 20 per 1000 and in the ex-miners 41 per 1000. In a group of 1902 leavers who did not have PMF at a medical examination conducted at most four years before leaving, 172 had developed PMF by the time of the follow up examination. Of these, 116 had had simple pneumoconiosis at the earlier examination. Cumulative exposure to respirable dust, category of simple pneumoconiosis, and age were each found to influence the probability of developing PMF in a subgroup of the 1902 men. Among the 1902 leavers, there was no overall progression or regression of simple pneumoconiosis.

Age Factors↗
PubMed1985

Study of lung function data by principal components analysis.

As a rational approach to the many lung function tests available, we have subjected the results of a battery of six lung function measurements made in 458 coalminers to the statistical technique of principal components analysis. By this means the six test results were reduced to three principal components without important loss of information. The first component appeared to represent lung size and the second the degree of airflow obstruction, and the third detected impairment of gas transfer factor in excess of that explained by the first two components. The values of the first principal component, used to select men with abnormal lung function, identified more younger men with functional abnormalities than a method based on comparison of observed and predicted values of forced expiration volume in one second. The values of the second and third principal components were used to classify types of functional abnormality. It is concluded that this statistical technique provides a sensitive method of identifying men with unusual lung function, particularly younger men, in a population and can be used to define and quantify different aspects of lung function.

Adult↗
PubMed1984

Epidemiological study of the lung function of workers at a factory manufacturing polyvinylchloride.

A preliminary epidemiological study has been carried out to investigate a report that some men working in a factory manufacturing polyvinylchloride (PVC) had abnormally low values of the single breath diffusing capacity for carbon monoxide (TLCO). All monoxide (TLCO). All 265 present and past employees of the PVC factory were studied, together with 219 men from the workforce of a nearby foundry. Each man's TLCO was measured and a smoking history and detailed occupational history obtained. The distribution of standardised TLCO results from all persons examined was symmetrical and did not indicate an unexpectedly high proportion of men with having allowed for age, height, weight, and smoking habit, TLCO was associated with a history of working in the PVC factory before 1975 (when levels of vinylchloride monomers (VCM) were much higher than subsequently), and slightly associated with working in jobs where exposure to VCM was likely to have been highest. The men with low TLCO also tended to have smoked more heavily than controls. The relative importance of occupational factors and smoking in relation to low TLCO is not clear, but the results give some support to the hypothesis that work in the PVC factory before 1975 entailed exposure to a substance that caused impairment of lung function in a small number of men.

Adult↗
PubMed1984

Classification of progressive massive fibrosis of coalminers by type of radiographic appearance.

In a pilot study the chest radiographic appearances of 112 coalminers who developed progressive massive fibrosis (PMF) over an 11 year period have been classified into six types based on the appearances of the large radiographic opacities. The most common type of PMF was one or more large shadows of homogeneous radiodensity. Less common types included markedly rounded shadows usually less than 3 cm in diameter, non-homogeneous shadows appearing to consist of conglomerations of small rounded opacities, and condensations of linear or streaky shadows. Good reproducibility by one reader between two readings were obtained. The lifetime exposures to mixed respirable coal mine dust, and to its quartz component, of these 112 men were compared with those of control subjects matched for age and starting category of simple pneumoconiosis but without PMF. Overall, the men with PMF had been exposed to more mixed dust than controls, confirming that one of the reasons some men with simple pneumoconiosis develop PMF is that they have inhaled more dust than others. Eleven of the 112 cases had large opacities that were not homogeneous and appeared to consist of conglomerations of "r" type small rounded opacities. The average quartz exposures of these men were much higher than in control subjects, suggesting that in this type of PMF quartz was an important causative factor.

Aged↗
PubMed1983

Histocompatibility antigens in coal miners with pneumoconiosis.

Twenty-five histocompatibility antigens have been measured in 100 coal miners with pneumoconiosis attending a pneumoconiosis medical panel and the results compared with a panel of 200 normal volunteers not exposed to dust. Chest radiographs were read independently by three readers according to the ILO U/C classification. On a combined score, 40 men were thought to have simple pneumoconiosis and 60 men complicated pneumoconiosis. The number of antigens tested and associations between antigens caused difficulties in assessing the statistical significance of differences in prevalence of antigens between groups of men. Using stringent criteria for statistical significance, no significant differences were found in antigen prevalences between miners and controls, or miners with simple or complicated pneumoconiosis. When a less stringent statistical approach was applied, three antigens appeared to have abnormal prevalences in these 100 miners by comparison with the normal volunteers. More detailed examination of these antigen prevalences in relation to radiographic category of pneumoconiosis did not provide any supportive evidence that these slight associations were of statistical or clinical significance. Reports on histocompatibility antigens in miners with pneumoconiosis are reviewed briefly and the results compared. There is no good evidence that any of the histocompatibility antigens so far tested are associated with a clinically important altered risk of simple or complicated pneumoconiosis when dust is inhaled.

Aged↗
PubMed1983

Clinical studies of workers exposed to polyvinylchloride dust.

A previous study showed that exposure of workers to polyvinylchloride (PVC) dust was associated with the presence of small rounded opacities in the chest radiograph, and also with a small average reduction of the forced expiratory volume in one second (FEV1). Studies have now been carried out on selected men to determine the clinical importance of the presence of small rounded opacities and also to identify any clinical or physiological features associated with PVC dust exposure. Among 28 men with small rounded opacities, complaints of persistent bronchial mucous hypersecretion were more common (nine men) than amont 29 men of similar age, smoking habits, and dust exposures (one man, p less than 0.01), and there was a suggestion that the physical sign of late inspiratory crackles was more frequent among men with opacities (seven of 27 men) than the other men (two of 28 men, p less than 0.05). The average lung function of men with opacities was only trivially lower than that of the comparative group and the difference between the groups was not significant. In further studies 13 non-smokers with the highest PVC dust exposure and lowest FEV1 (adjusted for age, height, weight, and dust exposure) were examined. None had an observed FEV1 less than 80% of the predicted value for age and height, and these men did not differ in symptoms, signs, or lung function from non-smokers with low dust exposure and similarly low FEV1. In a similar study of 18 smokers with the highest PVC dust exposures and lowest adjusted FEV1, some men had an observed FEV1 well below 80% of predicted values for non-smokers, but with one exception no clinical or functional differences were found between then and 18 smokers with low dust exposure and similarly low FEV1. The exception was again the presence of end inspiratory crackles on auscultation, which were slightly more frequent among men with the highest dust exposures (seven men) than among those with low exposure (two men, p less than 0.06). We conclude that these findings are consistent with the suggestion that the radiographic abnormalities caused by PVC dust exposure are not associated with important functional effects or clinical illness. Further studies are desirable to examine the eventual outcome of the syndrome.

Adult↗