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Biomedical subjects

T J Clark

Publications and source records attributed to T J Clark.

At least 73 records · Page 4Linked to original sources
PubMed1983

Intravenous ethanol can provide bronchodilatation in asthma.

1. The effect of intravenous infusions of saline, and 2, 4 and 8% (v/v in saline) ethanol in airflow were assessed in five normal male subjects and five male patients with asthma. 2. Normal subjects showed no response to intravenous ethanol at any dose. 3. In patients with asthma, specific airways conductance (sGaw) showed a sustained rise of approx. 32.8% from baseline with 8% ethanol which was not seen at lower doses. By contrast, salbutamol (400 micrograms by aerosol) caused a mean rise in sGaw of 84.4% from baseline. 4. Blood ethanol concentrations showed a sustained rise over the full duration of the study with 8% ethanol but not with lower doses. 5. Ethanol causes a sustained improvement in sGaw in patients with asthma (38.9% of the response to salbutamol) if blood ethanol levels are sufficiently elevated.

Adult↗
PubMed1983

The effect of posture on the sympathoadrenal response to theophylline infusion.

We studied the effect of posture on the sympathoadrenal response to intravenous theophylline in six normal subjects. On three separate occasions they received an intravenous infusion of either theophylline (6 mg/kg) while supine, theophylline (6 mg/kg) while standing or saline as placebo while standing. With the subjects standing theophylline caused tremor, a peak heart rate of 99 +/- 6 beats/min, and an elevation of plasma cyclic AMP from 9.3 +/- 0.7 to 15.1 +/- 1.7 nmol/1 (mean +/- s.e. mean). There was a small, but significant, elevation of plasma adrenaline, noradrenaline and glucose. The elevation in plasma catecholamines was insufficient to explain either the sympathomimetic effects of theophylline or the rise in plasma cyclic AMP. Theophylline had little or no effect with the subjects supine. The mean peak theophylline concentration following infusion was significantly higher with the subjects upright than when supine (18.3 c.f. 12.4 mg/l, P less than 0.025). However, adequate plasma levels of theophylline were obtained in all subjects when lying or supine. Analysis of individual data suggests that differences in plasma levels of theophylline are unlikely to account for the increased effects seen on standing. The mechanism of action of theophylline cannot be explained by increased secretion of catecholamines alone. Theophylline appears to amplify the increased sympathetic activity associated with standing and this is probably by phosphodiesterase inhibition.

Adrenal Glands↗
PubMed1983

Peripheral middle lobe syndrome.

Classically, the middle lobe syndrome has been described as being caused by a central obstruction. Clinical records and radiologic findings were reviewed in 129 patients examined between 1955-1981 who had chronic disease in the right middle lobe and/or lingula. Fifty-eight patients (45%) had no evidence of a central obstructive lesion. The majority were middle-aged women with histories of chronic cough and chest pain. Bronchoscopic and radiologic evaluation served to exclude central lesions. Surgical confirmation was available in 38 patients. Pathologic study showed varying degrees of chronic inflammation, pneumonia, and bronchiectasis. Surgical results were excellent in isolated disease. Chronic atelectasis and pneumonitis of the right middle lobe and/or lingula do not always imply central obstruction. A lack of collateral ventilation is a plausible theory to explain the pathophysiology in such patients.

Bronchiectasis↗
PubMed1983

Assessment of antitussive effects by citric acid threshold.

The cough threshold to citric acid inhalation was measured in eight subjects by single inhalations of increasing concentrations of citric acid until a cough was consistently produced. The cough threshold was measured before and after 60 mg glaucine, 60 mg codeine and matched placebo on three separate days a week apart. Base-line cough threshold in each subject was consistent from week to week. Codeine increased the threshold by more than one citric acid concentration in three subjects. Placebo and glaucine did not produce a threshold change of more than one citric acid concentration. We conclude that the citric acid threshold is a simple measure of antitussive activity. No such activity was found with glaucine.

Adult↗
PubMed1983

Treatment of airways obstruction.

This review of the treatment of airways obstruction attempts to demonstrate that treatment needs to be guided by an understanding of pathophysiology and pathogenesis as well as a knowledge of the natural history of the diseases underlying airways obstruction and their causes. This enables effective health education and prevention to be applied where appropriate and treatment itself to be directed in an intelligent and logical manner.

Adrenal Cortex Hormones↗
PubMed1983

Alcoholic drinks and asthma: a survey.

A questionnaire was designed to investigate how commonly alcoholic drinks affected asthmatic patients in a population of 168 patients with asthma. Fifty-four patients (32.1%) reported that one or more types of drink made their asthma worse, the main offenders being wines, beer and whisky. Thirty-nine patients (23.2%) reported that alcohol, usually brandy or whisky, made their asthma better, particularly when their symptoms were severe. Patients in this latter group tended to be older and were likely to have worse asthma than those who reported no improvement with alcohol (P less than 0.003). In all 47% of patients reported that alcoholic drinks affected their asthma, indicating a more frequent influence of alcohol than is usually appreciated.

Adolescent↗
PubMed1982

Irritant effects of cigarette and cigar smoke.

The effects of a cigar and five different cigarettes were assessed in six smokers and six non-smokers by measurement of reduction in specific conductance in the first 30 s after single inhalations of smoke. Responses to the cigar and high-tar cigarette were significantly greater than those to milder cigarettes. Differences in the depth of inhalation of smoke suggested adjustment of the manner of smoking according to the irritant qualities of the smoke. These findings show that large differences between cigarette constituents can be detected in immediate airway changes and that such irritant qualities affect the way in which cigarettes are smoked. Cigar smoke produced similar responses to an unfiltered cigarette at the top of the tar and nicotine range available in the U.K.

Adult↗
PubMed1982

A comparison of the effects of different methods of administration of beta-2-sympathomimetics in patients with asthma.

Double-blind cross-over studies of oral and inhaled terbutaline and salbutamol have been performed in two groups of asthmatic patients. Both drugs at the doses recommended by the manufacturers produced similar maximal effects. The onset of response was faster with inhaled treatment and there was no difference in length of action between the drugs or the routes of administration. Side-effects were much more common with oral treatment. In a separate study oral and inhaled terbutaline were compared in 11 asthmatic patients and this also showed a similar maximal response in tests of forced expiration. A greater response was seen in sGaw following inhaled treatment (P less than 0.05). These results suggest that beta-2-sympathomimetic drugs should be administered by the inhaled in preference to the oral route.

Administration, Oral↗
PubMed1982

Thyrotoxicosis and dyspnoea.

Shortness of breath is a common symptom in thyrotoxicosis and it may have a number of causes. We have studied dyspnoea, skeletal muscle power and respiratory muscle power in eleven patients who had thyrotoxicosis with no evidence of heart failure. Four patients (36.4%) had a marked improvement with treatment in the maximal inspiratory pressure developed at the mouth. All four were breathless and had a proximal myopathy before treatment. This confirms the existence of a group of thyrotoxic patients with a reversible respiratory muscle myopathy which may explain the frequent finding of breathlessness on exertion in such patients.

Adult↗
PubMed1982

Immediate response to cigarette smoke.

Using an automated method of calculating airways resistance in the body plethysmograph, we have investigated changes occurring immediately after inhalation of cigarette smoke. Decreases in specific conductance occurred by the time of the first measurement seven or eight seconds after exposure to single inhalations of cigarette smoke in 12 smokers and 12 non-smokers. Less than half of the initial change was present 40 seconds after the inhalation. Initial responses were greater in the non-smokers. Responses recurred with repeated inhalations in smokers and non-smokers. Prior administration of salbutamol and ipratropium bromide significantly inhibited the response and this inhibition appeared to be greater in non-smokers. Sodium cromoglycate inhaled as a dry powder had no effect on the response.

Adult↗
PubMed1982

Airways responses to oral ethanol in normal subjects and in patients with asthma.

The effect of oral ethanol on airflow was studied in 5 normal subjects and 5 patients with asthma. On 4 different study days, each subject was asked to drink 40 ml of either water or 20%, 40% or 60% ethanol, and measurements were made of specific airways conductance (sGaw), blood ethanol levels, pulse rate and blood pressure. In some subjects in both groups there was a significant immediate fall in sGaw after drinking ethanol (below 5% confidence limits). Once absorbed, ethanol had a slight bronchodilator effect in 2 normal subjects and in 3 patients with asthma (5% level). Sixty per cent ethanol, when drunk slowly, showed significant bronchodilatation in 4 out of 5 patients with asthma and in one normal subject (5% level) with no acute fall in sGaw. Pulse rate and blood pressure did not change after water, 20% and 40% ethanol in either group, but immediately after 60% ethanol normal subjects showed a significant rise in pulse rate (P less than 0.01) which was not seen in patients with asthma. The immediate changes in sGaw and pulse rate may be due to stimulation of irritant receptors in the upper airways. Ethanol may act directly on bronchial smooth muscle to produce bronchodilatation and may be useful as a bronchodilator when given intravenously.

Administration, Oral↗
PubMed1982

The importance of particle size in response to inhaled bronchodilators.

The effect of 250 micrograms terbutaline sulphate of three different particle sizes from a metered dose inhaler was examined in ten non-asthmatic and ten asthmatic subjects. Particle size ranges were approximately less than five micrometers, five to ten micrometers and ten to fifteen micrometers. Responses to the less than five micrometers range were significantly greater than those to the larger sizes in both groups of subjects. In the asthmatic patients there was a suggestion that the difference between small and large particles was more marked for V50 than sGaw reflecting poorer penetration of large particles into smaller airways.

Adolescent↗
PubMed1982

Safety of inhaled corticosteroids.

Corticosteroids effectively suppress asthma but have unwanted systemic side-effects which can be avoided if taken by inhalation. Inhaled corticosteroids are effective and although sensitive tests can occasionally detect some systemic activity with a daily dose of beclomethasone diproprionate of 400--800 micrograms, in clinical practice systemic side-effects are not seen. If this daily dose is raised above 1.5--2.0 mg systemic activity is more easily detected and is more likely to be of clinical significance. Local side-effects include occasional hoarseness and oropharyngeal thrush. There have been no reports of opportunistic pulmonary infections or bronchial epithelial damage following prolonged use. Inhaled corticosteroids are now in widespread us in over 100 countries throughout the world. They have also been employed for nearly a decade and this extensive clinical experience has not revealed significant systemic side-effects. This safety compares favourably with other asthma treatment and suggests that inhaled corticosteroids may be used when bronchodilators are failing to control symptoms and higher doses are thought necessary or being taken. Better asthma control should reduce bronchodilator consumption and the net incidence of side-effects. Inhaled corticosteroids can therefore safely provide effective treatment and steer a path between the risk of intensive bronchodilator treatment and those produced by systemic steroids.

Asthma↗
PubMed1982

Do oral and inhaled terbutaline have different effects on the lung?

The effect of inhaled or oral terbutaline on the subsequent response to inhaled terbutaline was studied using a double-blind cross-over technique in 12 asthmatic patients. 12 indices of respiratory function were obtained from the maximal flow-volume loop and a single-breath inert gas technique. These were used to evaluate the effect and to attempt to distinguish the site of action of the drug. Although the initial dose of inhaled terbutaline had a greater immediate effect than its oral counterpart there were no significant differences in the response to subsequently inhaled terbutaline. These findings do not support recent suggestions that oral administration has a greater effect on distal airways or promotes the effects of inhaled bronchodilators.

Administration, Oral↗
PubMed1982

Alcohol in asthma and the bronchoconstrictor effect of chlorpropamide.

The effect of drinking 40 ml of sherry on peak expiratory flow rate in 16 normal subjects and 19 patients with asthma was assessed after oral administration of either chlorpropamide or placebo. After placebo and sherry normal subjects showed no change in peak expiratory flow rate, while an increase was usually shown by patients with asthma. This bronchodilation was more marked in patients whose base-line peak flow rate was less than 50% predicted. Ingestion of chlorpropamide before sherry significantly modified the bronchodilating properties of sherry; five of the 19 patients with asthma showed airway narrowing on 11 of 19 occasions tested. Further studies in one patient suggest that this bronchoconstriction may be mediated by congeners in sherry rather than ethanol. These findings confirm the observation that chlorpropamide and sherry can cause airway narrowing in patients with asthma but shows that this response is not always reproducible. The bronchodilator effect of alcohol in patients with asthma may have therapeutic implications.

Adult↗