Biomedical subjects
Publications and source records attributed to A Guz.
Unmyelinated nerve fibres, probably sensory in type, are present in the human alveolar wall. It is possible that these fibres may be associated with juxta-capillary receptors which have been identified on physiological grounds in animals.
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1. The hypothesis that respiratory oscillations of arterial blood gas composition influence ventilation has been examined. 2. Phrenic motoneurone output recorded in the C5 root of the left phrenic nerve and the respiratory oscillations of arterial pH in the right common carotid artery were measured in vagotomized anaesthetized dogs which had been paralysed and artificially ventilated. 3. The effect of a change in tidal volume for one or two breaths on phrenic motoneurone output was measured with the inspiratory pump set at a constant frequency similar to, and in phase with, the animal's own respiratory frequency. A reduction of tidal volume to zero or an increase by 30% led to a corresponding change of mean carotid artery pH level. The changes of carotid artery pH resulted in a change of phrenic motoneurone output, predominantly of expiratory time (Te) but to a lesser extent of inspiratory time (T1) and also peak amplitude of 'integrated' phrenic motoneurone output (Phr). Denervation of the carotid bifurcation blocked this response. 4. The onset of movement of the inspiratory pump was triggered by the onset of phrenic motoneurone output. When a time delay was interposed between them, the phase relationship between respiratory oscillations of arterial pH and phrenic motoneurone output altered. The dominant effect was to alter Te; smaller and less consistent changes of Phr and T1 were observed. 5. When the inspiratory pump was maintained at a constant frequency but independent of and slightly different from the animal's own respiratory frequency (as judged by phrenic motoneurone output), the phase relationship between phrenic motoneurone output and the respiratory oscillations of pH changed breath by breath over a sequence of 100-200 breaths, without change of the mean level of arterial blood gas composition. Te varied by up to 30% about its mean value depending on the phase relationship. Ti and Phr were also dependent on the phase relationship but varied to a lesser extent. The changes were comparable to the results obtained in paragraph 4. 6. It was concluded that phrenic motoneurone output is dependent in part on its relationship to the respiratory oscillations of arterial blood gas composition. 7. Information concerning a transient ventilatory disturbance is stored in the arterial blood in the form of an altered pattern of the respiratory oscillations of blood gas composition; this in turn can change breathing by an effect on the carotid bodies.
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The levels of circulating complement components C3 and C4, total haemolytic complement, CH50, as well as evidence of complement activation, have been studied in peripheral blood samples during allergen-induced asthma. No evidence of activation of the complement system was detected in these studies.
A questionnaire relating to smoking habits, respirator symptoms, and health attitudes was administered to 10 498 secondary schoolchildren in 1975. The results reported in this paper indicate that children who smoke regularly have a higher prevalence of upper respiratory tract infections and a higher incidence of the respiratory symptoms, cough, phlegm production with a cold, and shortness of breath, compared with non-smokers. Children are aware of the risks of lung cancer when smoking, but less aware of the other more immediate health risks, and this is particularly so in the younger age groups. It is suggested that health education should be directed towards younger children and that more use should be made of the fact that smoking clearly makes them less healthy.
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Six patients in sinus rhythm with congestive heart failure due to either myocardial infarction or cardiomyopathy, were given oral frusemide to eliminate oedema. Symptomatic relief occurred as body weight was reduced, and after a 'dry' basal weight had been achieved, progressive-load exercise testing was done to examine any benefit that derived from adding oral digoxin to the diuretic. Three pairs of sub-maximal exercise tests were done at intervals over three months, and the responses of each patient when using digoxin and diuretics were compared with those when using diuretics alone. One patient did not complete this study, because more frequent premature beats and increased angina followed the withdrawal of digoxin. For the five patients who completed three pairs of tests, there was no significant change in symptoms, in workload achieved, or in heart rate, respiratory rate, ventilation and respiratory quotient, whether digoxin was added or removed. It is concluded that in these patients where salt and water retention was controlled with diuretics, digoxin did not improve the capacity for exercise, and it is suggested that for such patients with myocardial disease in sinus rhythm, treatment should begin with diuretics.
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