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Biomedical subjects

I Webster

Publications and source records attributed to I Webster.

At least 19 recordsLinked to original sources
PubMed1979

Lung function in an Australian population: 2. Spirometric performance and cigarette-smoking habits.

The FEV1, FVC and FEV1/FVC% in 12016 females and 18 359 males were related to cigarette-smoking habits. Over all, non-smokers had significantly better lung function than cigarette smokers. Ex-smokers of either sex had significantly higher FEV1 and FEV1/FVC% than cigarette smokers, but the FVC values were higher only in females. With consumption in excess of 10 cigarettes per day, deterioration in lung function was manifest in both sexes, but was greater in males than females. The mean chronological age of males who smoked from 30 to 50 cigarettes per day was 12.9 years and 9.6 years less than would have been predicted on the basis of their FEV1 and FVC values respectively. The corresponding values in women were 9.3 years and 7.9 years respectively. Additionally, the deterioration in lung function with increasing age was greater in cigarette smokers than in non-smokers.

Adolescent↗
PubMed1979

Lung function in an Australian population: 1. Spirometric standards for non-smoking adults.

Relationships between age, height, weight and spirometry with FEV0.5, FEV1, FVC and FEV1/FVC are described for a sample of 6275 female and 6511 male non-smoking adults living in New South Wales. Prediction equations for ventilatory function tests are derived from non-smokers and compared with other standards that are available in a population sample of 31172 subjects. It is concluded that the standards described in this paper are more appropriate for use in Australian populations. Nomograms for predicting FEV1 and FVC in females and males are provided.

Adolescent↗
PubMed1979

Risk of asbestosis in crocidolite and amosite mines in South Africa.

X-rays of all while and mixed-race men employed in crocidolite and amosite mines and mills were read independently by three experienced readers according to the ILO U/C classification. Abnormality was regarded as present if reported by two or more readers. Parenchymal abnormality, defined as the presence of small irregular opacities of profusion 1/0 or greater, was found in 7.3% of the workers. Pleural thickening was found in 4.5% of the workers, costophrenic angle obliteration in 3.2%, and pleural calcification in 1.7%. The prevalences of both pleural and parenchymal abnormality were strongly related to the duration of exposure to asbestos at work. The overall prevalence of abnormality increase from 4.0% in men with exposure for 1 year or less to 47.9% in men with more than 15 years of exposure. After taking into account the effects of age and duration of asbestos exposure, the prevalence of pleural abnormality was not predicted by fiber concentration. However, white men working with amosite tended to develop a higher prevalence of pleural abnormality than did those working with crocidolite. Compared to whites, men of mixed race, who only work with crocidolite, had a high prevalence of pleural abnormality in each exposure duration category. In contrast to pleural abnormality, the prevalence of parenchymal abnormality, after taking into account the effects of age and duration of exposure, was significantly predicted by fiber concentration but not by race or asbestos type. Our results suggest that parenchymal abnormality in workers in South African asbestos mines could be largely prevented by reducing exposure to fibers visible under the light microscope. However, this may not be the case for pleural abnormality.

Adult↗
PubMed1978

Mesothelioma in relation to asbestos fibre exposure. A review of 70 serial cases.

Seventy consecutive patients suffering form mesothelioma of the pleura were referred to the National Research Institute for Occupational Diseases. In only 1 case was it not possible to elicit a history of significant exposure to asbestos dust. An occupational and environmental history must be taken by a knowledgeable person before it is possible to conclude that there has been no asbestos exposure.

Asbestos↗
PubMed1978

Lead and morbidity: A dose-response relationship.

Many laboratory tests have been recommended for monitoring factory workers exposed to lead. To select the most useful test the best predictor of selected measures of morbidity was sought. 639 lead-exposed workers in several factories were questioned about abdominal ache, constipation, and fatigue and were examined for hand tremot. Packed-cell volume, blood-lead, urinary lead, and delta-aminolaevulinic acid were estimated in 489 workers. About half of the values for the latter three tests fell into the "excessive" or "dangerous" category of lead absorption. Blood-lead was a better predictor of morbidity than any other laboratory test, and further information did not add appreciably to morbidity prediction. The findings suggest that blood-lead measurement is the most meaningful test for monitoring workers exposed to lead. The effect of lead on morbidity does not appear to depend on its action on the porphyrin metabolic pathway.

Abdomen↗
PubMed1978

Ultrastructure of the lung in the rat following exposure to crocidolite asbestos and quartz.

Lung tissue from rats that had inhaled U.I.C.C. crocidolite asbestos or quartz particles showed thickening of the interstitial tissue and the presence of collagen fibres. Aggregates of macrophages in the alveolar spaces were a dominant feature of all the sections examined from asbestos exposed rats. According to the ultrastructural studies described here, all the macrophages were mature cells, indicating that the ingested crocidolite asbestos was non-toxic. Lung sections of rats exposed to quartz particles were significantly different. Single cells were found in the alveolar spaces and many macrophages showed a characteristic pattern of vacuole formation. Other cells contained intracellular membranous lamellated bodies, similar to those found in Type II pneumocytes. Cells containing lamellated bodies were also found in the interstitial tissue. These findings suggest that the two mineral dusts have quite different biological effects on the macrophage and that the development of pulmonary fibrosis may, to some extent, be caused by a different mechanism in each instance.

Animals↗
PubMed1977

Drinking, smoking and drug-taking patterns in a predominantly lower socioeconomic status sample: comparison with Medicheck sample.

The drinking, smoking, and drug-taking patterns of 9829 adult members of the Australian Workers Union in Sydney are compared with data collected through the Medicheck Referral Centre. Overall, the two sets of data are very similar, but the results of this survey point to the high prevalence of heavy alcohol consumption, and of regular drug-taking in young people.

Adolescent↗
PubMed1977

Pneumoconiosis in non-mining industries on the Witwatersrand.

Two hundred and eighty-seven patients referred to the National Research Institute for Occupational Diseases with suspected pneumoconiosis are recorded. The patients are classified according to the type of dust to which they were exposed, and by occupation or industry. Radiological evidence of pneumoconiosis according to ILO/UICC classification is the only acceptable basis for compensation at present, and the number of patients so diagnosed is also given. None of these figures show the true distribution and incidence of pneumoconiosis as a form of occupational disease on the Witwatersrand. They only indicate the presence of pneumoconiosis not associated with mining and reflect a wide range of occupations.

Asbestosis↗
PubMed1977

The effect of vinyl chloride monomer, chloroethylene oxide and chloracetaldehyde on DNA synthesis in regenerating rat liver.

Vinyl chloride monomer used in the manufacture of polyvinyl chloride is a chemical of increasing industrial importance but has recently been incriminated as a carcinogen, producing a mutagenic effect after being metabolized to active metabolites. The initial effect of vinyl chloride monomer and two of its presumed metabolites, chloracetaldehyde and chloroethylene oxide, on DNA synthesis was investigated in vivo in regenerating rat liver. The established control curve for the DNA synthesis rate after partial hepatectomy demonstrated two waves of synthetic activity at 21 and 30 h. Vinyl chloride, injected intravenously immediately on completion of the operation, depressed the first wave of DNA synthesis by 49.6%. The second peak of DNA synthetic activity was similar to that of the control. Chloracetaldehyde and chloroethylene oxide both produced similar effects on the first wave of DNA synthesis after partial hepatectomy, inhibiting the DNA synthesis rate by approx. 50%. After a regenerating period of 27 h, however, they produced very different effects, chloroethylene oxide raising the control DNA synthesis rate at 30 h by 49% while chloracetaldehyde tended to desynchronize the well-defined second peak of the control. The test compounds have been compared to literature reports of the inhibitory effects of various carcinogens on DNA synthesis.

Acetaldehyde↗
PubMed1977

Immunological studies of patients with asbestosis. II, Studies of circulating lymphoid cell numbers and humoral immunity.

As part of an overall assessment of immunological function, several aspects of humorial immunity and circulating lymphocyte subpopulations were evaluated in a group of twenty-six patients with radiographic evidence of parenchylmal asbestosis. Statistical comparisons were made between the patient group and a comparable group of forty-five controls. Both the percentages and absolute numbers of circulating T lymphocytes were significantly reduced in the patient group compared with controls. Significant elevations of salivary secretory IgA and of serum IgA, IgG, IgM and IgE were noted amongst the patients compared with the controls. Non-organ-specific autoantibodies and cold-reactive lymphocytotoxins were present in high frequency in the patients' sera. Neoplasms were detected in four of the patients. The possible significance of these findings is discussed.

Antilymphocyte Serum↗
PubMed1977

Immunological studies of patients with asbestosis. I. Studies of cell-mediated immunity.

A variety of cancers have been documented in patients exposed to asbestos dust. Since a deranged immune system may play a rôle in cancer development, the general level of immunocompetence was studied in a group of twenty-six patients with radiographically defined asbestosis, who might be at risk of developing asbestos-related neoplasms. Statistical comparisons were made with a comparable control group. A disproportionate number of the patients displayed cutaneous energy to certain recall antigens and to 2,4-dinitrochlorobenzene. In vitro studies of cellular immunity, as evaluated by phytohaemagglutinin-induced proliferative and cytotoxicity assays, showed significantly lower values amongst the patient group. Serum inhibitors of mitogen-induced lymphocyte transformation were also detected in several of the patients. The possible significance of these findings is discussed.

Adult↗
PubMed1976

The obligations of medical practitioners in relation to the new Mines and Works Act.

The Occupational Diseases in Mines and Works Act No. 78 of 1973 deals with compensation to be paid in cases of pneumoconiosis and other compensatable diseases such as tuberculosis, permanent obstruction of the airways and scleroderma. Any medical practitioner who attends a miner or worker from a 'works' such as Iscor, Amcor and several others at present controlled, is obliged, if death occurs, to remove the cardiorespiratory organs and forward them to the Medical Bureau for Occupational Diseases, unless the near relatives refuse permission for an autopsy. A pathologist who performs a routine autopsy on such a person must follow the same procedure.

Autopsy↗