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Biomedical subjects

A J Woolcock

Publications and source records attributed to A J Woolcock.

18 recordsLinked to original sources
PubMed1979

Relationship between bronchial and arterial diameters in normal human lungs.

In order to find an objective method for measuring narrowing of small airways, eight lungs from four people without lung disease were inflated and fixed at 25 cm of water pressure. Eight to nine blocks were taken at random from each of six parasaggital slices from each lung, sectioned, and stained. The size of the bronchioles (airways without cartilage) in relation to their accompanying arteries was determined. The internal bronchiolar diameter was compared with three different arterial diameters (the internal, external medial, and external adventitial). The ratio of the internal bronchiolar diameter to the external adventitial arterial diameter was constant between lungs (0.62 +/- 0.02) and independent of the method of inflation or the position within the lungs. This ratio may provide a useful index of bronchiolar narrowing in disease.

Adolescent↗
PubMed1979

Arterial blood gas tension changes at the start of exercise in chronic obstructive pulmonary disease.

In a previously reported study of a group of normal subjects, large decreases in arterial O2 tension (PaO2) of as much as 37 mm Hg were measured during the first 90 sec of slow stair-climbing exercise (chosen as a common daily exertion). This study reports the changes in PaO2, arterial CO2 tension (PaCO2), and ventilation in 7 patients with chronic obstructive pulmonary disease and resting hypoxemia during the first 90 sec of similar exercise. The patient group showed significantly smaller unsteady-state decreases in PaO2 starting from a smaller resting value (patient group, 72 +/- 2.6 mm Hg, mean +/- SE; normal group, 92 +/- mm Hg; P less than 0.001) and decreasing to a similar smallest value (patient group, 58 +/- 3.8 mm Hg; normal group, 65 +/- 3.4 Hg; P greater than 0.05). PaCO2 tended to oscillate around the resting value in both the patient group and the normal group, and the rates of increase in ventilation in the 2 groups were similar. The physiologic processes that could limit the unsteady-state decrease in PaCO2 in the patient group are analyzed, the analysis suggesting that a slower rate of increase in tissue consumption of O2 is most likely to account for the smaller decrease in PaO2.

Adult↗
PubMed1979

Correlation between the function and structure of the lung in smokers.

To study the relationship between morphologic changes and alteration of lung function, the excised lobes of 21 smokers and one nonsmoker who required lobectomy for small peripheral tumors were inflated and fixed in formalin, and measurements of bronchiolar narrowing and degree of emphysema were made. All patients had comprehensive pulmonary function tests (including diffusing characteristics, the single-breath N2 test, measurements of elastic recoil, and flow-volume measurements with air and helium) performed before lobectomy. Eight of the lobes excised from the smokers had emphysema of grade 15 or more, the greatest being grade 50. Lobes from 11 patients had evidence of airway narrowing. There were 6 lobes with both emphysema and airway narrowing. Pulmonary function was abnormal in some aspect in all lobes except that from the nonsmoker. Whereas the tests of diffusing capacity, particularly the fractional uptake of CO, correlated with the degree of emphysema, the tests of elastic recoil were not predictive of this early degree of emphysema. The degree of small-airway narrowing correlated with maximal mid-expiratory flow rate and the single-breath N2 test. The maximal flow/static recoil pressure curves were the most sensitive indicators of airway abnormality in the patients with emphysema.

Aged↗
PubMed1979

The influence of lower respiratory illness in infancy and childhood and subsequent cigarette smoking on lung function in Sydney schoolchildren.

A prospective study of respiratory illness history and lung function of 10,898 school children in Sydney was begun in 1971. At the first visit, a history of previous asthma and of bronchitis before and after the first 2 years of life was obtained from a parental questionnaire, and maximal expiratory flow-volume curves were recorded. These lung function studies were repeated yearly between 1972 and 1974, at which time a history of respiratory illness during the previous 12 months and a personal smoking history were recorded, Two groups of children from a random selection of primary and secondary schools in Sydney were studied. Their respective mean ages were 8.9 yr (primary group) and 12.6 yr (high school group) in 1971. Mean values for the maximal flow at 50 percent of the forced vital capacity were lower in children with a history of bronchitis and/or asthma than those in the control group. This was true in both age groups in both sexes. No differences were found in the 0.5-s forced expiratory volume or forced vital capacity. The differences in maximal flow at 50 per cent of the forced vital capacity were present again in 1974. In 1974, the data from smokers were compared with those from nonsmokers; small differences were found. The results suggest that bronchitis in infancy and childhood as well as asthma may affect lung function as children grow, that the abnormality may not be detected by the forced expiratory volume, that the abnormality persists, and that it is possible that the abnormality is further affected by smoking.

Adolescent↗
PubMed1979

Bronchodilator drugs.

Explore the source record for details and available documents.

Adrenergic alpha-Agonists↗
PubMed1978

Stratification of inspired air in the elongated lungs of the carpet python, Morelia spilotes variegata.

Using lung gas tensions via a triple lumen catheter to monitor ventilation distribution (VA) and radioactive techniques to study blood flow distribution (Q), the distribution of ventilation to perfusion ration (VA/Q) was studied in the elongated alveolar lung of the Carpet Python, Morelia spilotes variegata. In the resting, sleeping and agitated states both alveolar oxygen (PAO2) and carbon dioxide tensions (PACO2) were 'stratified' (unevenly distributed) within the alveolar lungs at end inspiration, during breath holding for up to 6 minutes and, when VA was low, at end expiration. The blood flow was also stratified. The degree of stratification of VA was influenced by the rate and depth of breathing and the length of the breath hold which preceeded the gas sampling. Similar results were obtained with a glass lung model. In both resting and sleeping states VA/Q ratios were similar over the proximal 75% of the alveolar lungs whereas VA nearly always exceeded Q over the distal 25%. The anatomic features of the lung are proposed as a possible mechanism for maintaining a uniform VA/Q distribution. Since the anatomical arrangement places the heart at the apical regions of the lungs, absence of cardiac mixing, combined with low respiratory rates, enables stratification to continue for very long periods within the aveolar lungs of the snake.

Animals↗
PubMed1978

Tyrophagus putrescentiae: an allergenically important mite.

The incidence of positive skin tests to the mite Tyrophagus putrescentiae was measured and compared with skin reactions to Dermatophagoides pteronyssinus and other allergens in Australian and New Guinean populations, and mite counts were determined in Sydney and New Guinea houses. Positive reactions to T. putrescentiae were as frequent as those for D. pteronyssinus in asthmatics in Sydney and were the commonest positive reactions in the normal New Guinea population. T. putrescentiae-specific serum IgE levels were determined and some IgG cross-reactions of D. pteronyssinus and T. putrescentiae antigens were demonstrated. It is suggested that T. putrescentiae is an important source of allergen and should be considered whenever D. pteronyssinus is thought to be a problem. A convenient method for culturing and isolating T. putrescentiae is described.

Allergens↗
PubMed1978

Atopy and bronchial reactivity in Australian and Melanesian populations.

In order to compare the prevalence of atopy and bronchial hyperreactivity among Papua New Guinian (P.N.G.) and Australian populations, skin prick tests and methacholine bronchial challenge tests were performed. A civilian and an army population from each country were examined and those with past or present asthma, recent respiratory tract infection and chronic lung disease were excluded. No statistical difference in the prevalence of atopy was found between the four populations. In the P.N.G. population 40 and 49%, and in the Australian population 27 and 39%, were found to be atopic, without symptoms of past or present allergic disease. The house dust mites were the commonest allergens in all populations. In response to methacholine (0.3 mg), only 6% of subjects had falls in 1 sec forced expiratory volume (FEV1) of more than 12% (upper limit of normal range) and only two were in the asthmatic range. There was no correlation between the degree of bronchial hyperreactivity and atopic status; however, the degree of bronchial hyperreactivity was slightly greater in the New Guinea civilian than in the Australian civilian population. In the absence of asthma, atopic status does not appear to cause increased bronchial reactivity, suggesting that some factor other than atopy must be present for the development of bronchial hyperreactivity characteristic of asthma.

Adolescent↗
PubMed1978

Changes in arterial blood gas tensions during unsteady-state exercise.

Arterial oxygen (Pao2) and carbon dioxide (Paco2) tensions and inspired minute ventilation were measured during the first 2 min of stair-climbing exercise in nine normal subjects. The subjects climbed a staircase at a rate of approximately 9 m vertical height every minute and arterial blood was drawn from an indwelling cannula at 15-s intervals. Large falls in Pao2 from a resting value of 92 +/- 2.0 (mean +/- SE) Torr to a lowest value of 65 +/- 3.4 Torr were recorded in the first 50 s of exercise while Paco2 oscillated around the resting value. Most subjects demonstrated an initial plateau of Pao2 for at least 7 s followed by a rapid fall and subsequent rise toward the resting level after 1 min. The falls in Pao2 measured were larger than those reported for laboratory exercise. The possible reasons for this discrepancy are discussed.

Adult↗
PubMed1977

The effects of smoking on the lungs.

The literature relating to tobacco smoking has been reviewed and is discussed under a number of headings. The smoking habits of Australians and people of other countries, the constituents of tobacco smoke and the different types of tobacco are discussed. The effects of tobacco smoke on lung defences and and function are outlined and the evidence relating cigarette smoking to lung cancer in Australia, the UK and the USA is reviewed. The relationship between cigarette smoking and diseases which chronic air flow obstruction is outlined. Differences in smoking-related diseases in males and females and the effects of stopping smoking are included in the discussion.

Adolescent↗
PubMed1977

Cigarette smoking in a cohort of Sydney schoolchildren: 1971--1974.

Cigarette smoking habits of a cohort of Sydney schoolchildren aged 12--13 years in 1971 have been recorded for four years. Smoking prevalence increases steadily over those years, 2.3% of boys and 0.5% of girls smoking 20 or more cigarettes a week at age 12.7 years in 1971, rising to 23.6% of boys and 17.6% of girls by age 15.6 years in 1974. A substantial increase in smoking prevalence in children aged 15.6 years was found in 1974 compared with a similarly aged group studied by the National Health and Medical Research Council (Australia) Subcommittee on Smoking in 1968. Quite a few children changed their smoking habits during the study. Children who changed or left schools smoked more than children who remained at the one school. Attacks of asthma or bronchitis were not related to smoking except that girls who were very heavy smokers reported more of these illnesses in 1974. No changes in lung function could be attributed to smoking by age 14.6 years. New approaches to smoking need to be evaluated in view of its rising prevalence, especially among older schoolchildren.

Adolescent↗
PubMed1976

Immediate hypersensitivity: a clinical review.

Diseases in which immediate hypersensitivity (IH) reactions occur, (asthma, allergic rhinitis and eczema) are very common in Australia although their overall prevalence is unknown. Until recently the clinical investigation of IH has been undertaken almost exclusively by allergists using scratch tests. The discovery of Ige by Ishizaka et al. in 1966 resulted in a rapid increase in the understanding of the processes involved in IH reactions and, although much remains unclear, respiratory physicians,immunologists and epidemiologists are becoming increasingly involved in investigating the IH reactivity of individuals and populations. In this review the immunological basis of IH reactions is briefly presented; the role of skin tests in their assessment is evaluated and the relationship between IH and clinical allergic disease is discussed in terms of patient management.

Adolescent↗