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Biomedical subjects

N C Thomson

Publications and source records attributed to N C Thomson.

At least 127 records · Page 7Linked to original sources
PubMed1982

Bronchial responsiveness to histamine or methacholine in asthma: measurement and clinical significance.

Quantitative measurement of nonspecific bronchial responsiveness can be simply and reproducibly made by inhalation tests with histamine or methacholine. Responsiveness to histamine correlates closely with responsiveness to methacholine. The degree of responsiveness relates closely with the presence and severity of asthma. The greater the increase in responsiveness the lower the peak flow rate (PFR) on waking, the greater the improvement in PRF after bronchodilator, the greater the diurnal variation of PFR, the easier is bronchoconstriction induced by nonspecific and allergic stimuli and the more treatment is required to control symptoms. Nonspecific responsiveness can be increased by exposure to respirable allergens or occupational sensitizers, and by infection. The observations suggest that measurement can be used in clinical practice to diagnose the presence of asthma, to help assess the severity of asthma and, in the assessment of occupational asthma, to determine if exposure can heighten bronchial responsiveness.

Asthma↗
PubMed1981

Comparison of bronchial responses to prostaglandin F2 alpha and methacholine.

We examined bronchial responsiveness to prostaglandin (PG) F2 alpha to determine its applicability in clinical practice and to compare it with bronchial responsiveness to the pharmacologically dissimilar agent, methacholine. Inhalation tests with two fold increasing concentrations of the two agents were carried out in 19 asthmatic and four normal subjects. The results were expressed as the provocation concentration causing a 20% fall in forced expiratory volume in 1 sec (PC20). The range of concentrations required to determine the PC20 was greater with PGF2 alpha (0.0001 to less than 5 mg/ml) than that with methacholine (0.07 to 30.96 mg/ml). Side effects of cough, retrosternal irritation, and expectoration of sputum were more frequent after PGF2 alpha. Repeat measurements in the same subjects showed that response to PGF2 alpha were as highly reproducible (r = 0.98, p less than 0.001) as previously reported with methacholine, and there was a cumulative dose effect (p less than 0.001). PC20PGF2 alpha correlated with PC20 methacholine (r = 0.5, p less than 0.01), but to a lesser degree than was previously demonstrated between histamine and methacholine. The poorer correlation was explained by the results of four subjects tolerant to PGF2 alpha relative to methacholine, three of whom were aspirin (ASA) intolerant; the correlation was much stronger when these subjects were excluded from analysis (r = 0.91, p less than 0.001). The results suggests that (1) PGF2 alpha is not a suitable agent to use in clinical practice to measure nonspecific bronchial responsiveness because of the wide dose range and unpleasant side effects, (2) the bronchial responsiveness of different individuals to PGF2 alpha and methacholine is usually well correlated and is thus unrelated to specific receptor activity, and (3) there is a relative reduction in responsiveness to PGF2 alpha in some asthmatics, particularly those with ASA intolerance.

Adult↗
PubMed1980

Effect of FPL57787 in exercise-induced asthma.

In ten patients with extrinsic asthma the effects of a new oral chromone FPL57787 and placebo were studied in a random double-blind fashion to assess the effect of FPL57787 in preventing exercise-induced asthma (EIA). Exercise testing consisted of steady state running on an inclined treadmill for up to 8 min. FPL57787 gave significant protection (P less 0.01) compared to placebo from the maximum percentage fall in FEV1, FVC and MMEF after exercise. FPL57787 also produced a small but significant (P less than 0.01) percentage increase in FEV1 2 hr after the drug compared to placebo, whereas no significant increase was seen in FVC or in MMEF.

Administration, Oral↗
PubMed1980

Effect of inhaled H1 and H2 receptor antagonist in normal and asthmatic subjects.

The effects on airflow resistance of an inhaled H1 receptor antagonist, clemastine, and an H2 receptor antagonist, cimetidine, have been investigated in normal and asthmatic subjects. No significant changes in specific conductance (sGaw) were seen in six normal subjects. In eight asthmatic subjects a significant increase in forced expiratory volume in one second (FEV1) occurred at 60 min (< 0.02), and 120 (< 0.05) after the inhalation of clemastine, whereas inhaled cimetidine had no effect on airflow resistance. Clemastine and cimetidine were tested on histamine-induced bronchoconstriction in eight normal and eight asthmatic subjects. Clemastine significantly reduced the fall in sGaw in normal subjects and the fall in FEV1 in asthmatic subjects, whereas cimetidine had no protective effect. Clemastine and ipratropium bromide were tested on methacholine-induced bronchoconstriction in eight normal subjects. Ipratropium bromide, but not clemastine, significantly reduced the fall in sGaw after methacholine. These results suggest that in normal and asthmatic subjects histamine-induced bronchoconstriction is mediated predominantly via H1 rather than H2 receptors in the airways.

Adolescent↗
PubMed1978

Effect of dopamine on airways conductance in normals and extrinsic asthmatics.

1 Specific conductance was measured before and after infused and/or inhaled dopamine in nine normal subjects and twelve patients with extrinsic bronchial asthma. 2 There was no significant change in conductance in either group. 3 The alpha-adrenergic receptor antagonist thymoxamine infused in combination with dopamine had no significant effect on conductance in three asthmatics. 4 It is concluded that dopamine has no acute effect on airways resistance and that specific dopamine receptors are unlikely to exist in human airways.

Adolescent↗
PubMed1978

Lymphocyte transformation in extrinsic bronchial asthma.

Lymphocytes from sixteen patients with extrinsic bronchial asthma and sixteen normals were investigated for their in vitro reactivity to stimulation with phytohaemagglutinin (PHA) and concanavalin A (Con A). No significant differences in maximum lymphocyte responses to PHA or Con A, either in the presence of foetal calf serum or autologous plasma, were found. The significance of these results in relation to T suppressor cell control of IgE formation is discussed.

Adolescent↗
PubMed1978

Sodium cromoglycate and ipratropium bromide in exercise-induced asthma.

In thirteen patients with extrinsic asthma the effects of placebo, sodium cromoglycate, ipratropium bromide, and ipratropium bromide plus sodium cromoglycate were studied in a random double-blind fashion to assess their inhibitory action in exercise-induced asthma (EIA). Exercise testing consisted of steady state running on an inclined treadmill for up to eight minutes. In eight of the 13 patients studied the baseline ratio of expiratory flow at 50% vital capacity (VC) breathing helium-oxygen (V50He) to V50air was over 1.20 and they were called responders; the remaining five patients were called non-responders. There was a significantly lower baseline maximum mid-expiratory flow rate (MMEF) in non-responders (P less than 0.02) as compared to responders but no difference in forced expiratory volume in one second (FEV1) or forced vital capacity (FVC). Sodium cromoglycate (P less than 0.02), ipratropium bromide (P less than 0.01), and ipratropium bromide plus spdium cromoglycate (P less than 0.01) all significantly inhibited the percentage fall in FEV1 after exercise in the responders. Ipratropium bromide had no preventive action on non-responders, unlike sodium cromoglycate (P less than 0.05) and ipratropium bromide plus sodium cromoglycate (P less than 0.02). It is postulated that mediator release is an important factor in development of EIA in most extrinsic asthmatics, whereas cholinergic mechanisms are relevant only in those patients in whom the main site of airflow obstruction is in the large central airways.

Adolescent↗
PubMed1977

Increase in peripheral blood 'null' cells in extrinsic bronchial asthma.

Lymphocyte subpopulations were measured in the peripheral blood of fifteen patients with extrinsic bronchial asthma and twenty-seven normal control subjects. No significant differences in the absolute numbers of relative proportions of T, B or K lymphocytes were found. Antibody-dependent lymphocyte-mediated cytotoxicity (K-cell activity) was also found to be normal. The proportion and absolute number of 'null' cells were significantly increased in the asthmatic group: this population did not correlate with serum IgE levels, the eosinophil count or the duration of disease. The significance of these results in relation to suppressor T-cell control of IgE formation is discussed.

Adolescent↗
PubMed1976

Immunological studies in pre-eclamptic toxaemia.

Although five patients with severe pre-eclamptic toxaemia (PET) had increased anticomplementary activity in their serum, there was no evidence of complement activation in the plasma of four of the five patients. These results are not implicated in the pathogenesis of PET. No significant correlation was found between anticomplementary activity and pregnancy-associated alpha2-glycoprotein.

Antigen-Antibody Complex↗