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E F Juniper

Publications and source records attributed to E F Juniper.

87 records · Page 5Linked to original sources
PubMed1984

The effect of atropine on allergen-induced increases in bronchial responsiveness to histamine.

We examined the role of cholinergic mechanisms in causing the increase in histamine bronchial responsiveness that follows allergen exposure. Five stable adult atopic asthmatics received inhalation tests with histamine on 2 days after both placebo and a dose of atropine sulphate (18 mg nebulized during tidal breathing), which reduced saliva output. On a third day, an allergen inhalation test was carried out to stimulate a dual asthmatic response. When the FEV1 had returned to within 10% of baseline, the histamine test was repeated after placebo and atropine. Before allergen inhalation, atropine marginally increased the FEV1 (p = 0.12) and reduced bronchial responsiveness to histamine (p = 0.003). When allergen challenge had induced an increase in histamine responsiveness (p = 0.001), atropine again marginally increased FEV1 (p = 0.063) and reduced the responsiveness (p = 0.004) but did not return the responsiveness to the preallergen level (p = 0.023). There was no evidence that the magnitude of the atropine blockade of histamine responsiveness was different before and after allergen (p = 0.92). We conclude that cholinergic mechanisms are not likely to explain the increase in bronchial responsiveness that follows allergen-induced inflammation.

Adult↗
PubMed1982

Long-term stability of bronchial responsiveness to histamine.

Bronchial responsiveness to histamine was measured in 35 adult asthmatics whose symptoms were controlled on a minimum of medication. The tests were carried out on two occasions separated by 10-30 months. On each occasion the subjects had no symptoms of respiratory infection and no exposure to relevant allergens for at least six weeks. Bronchial responsiveness did not change in those who required no medication or inhaled salbutamol only to control their symptoms, but was significantly improved in those who required continuous treatment with both beclomethasone and salbutamol (p = 0.03). The results suggest that non-specific bronchial responsiveness remains similar over long periods when exacerbating factors are not present and that treatment with beclomethasone may reduce hyperresponsiveness.

Adult↗
PubMed1982

The perception of breathlessness in asthma.

We studied the perception of breathlessness as a function of air flow obstruction in 45 asthmatic subjects using a category scaling technique. Air flow obstruction and breathlessness were induced by inhalations of histamine acid phosphate in twofold-increasing concentrations from 0.03 to 16 mg/ml. The FEV1 was measured after each inhalation of histamine, and the subject was asked to rate his symptoms of breathlessness. The results showed that breathlessness increased as the FEV1 decreased but, despite a close linear relationship in all subjects (mean r = 0.88 +/- 0.15 SD), there was a considerable variation in the severity of breathlessness for any particular degree of air flow obstruction (mean intercept, 0.50 +/- 0.89 SD). However, the increase in sensory magnitude with increasing air flow obstruction did not show the same degree of variability (mean slope, 0.13 +/- 0.06 SD). The variability in breathlessness in asthmatic patients is likely to have many components. Two of these components were identified. First, we found that there was less respiratory distress in those subjects in whom air flow obstruction was present at the onset of the study. However, the presence of air flow obstruction at this time does not result in a reduction in sensation for further increases in air flow obstruction as might be expected from discrimination studies. Second, there was a significant relationship (p less than 0.01) between bronchial responsiveness and the magnitude of respiratory distress. Those subjects highly responsive to histamine experienced less respiratory distress than the less responsive subjects.

Adolescent↗
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

Effects of oxatomide compared with chlorpheniramine in allergic rhinoconjunctivitis.

Oxatomide is an H1 receptor antagonist, which also inhibits antigen-induced mediator release from sensitized mast cells and basophils. The effects of ingested oxatomide (30 mg/capsule) were compared with those of chlorpheniramine (5 mg/capsule) in a double-blind non-crossover study in two groups of twenty-five subjects with ragweed pollen-induced hay fever during the pollen season. Oxatomide or chlorpheniramine was started when symptoms became troublesome and was used in a dose of two to four capsules daily according to severity. Other medications were added, in a standardized way, if hay fever symptoms were not controlled by the test capsules. Forty-one subjects completed the study; nineteen received oxatomide and twenty-two chlorpheniramine. Mean symptom scores, number of test capsules and number of doses of additional medication were not significantly different between the two groups. Drowsiness was reported by subjects in both groups but was worse in the chlorpheniramine group (P less than 0.05). We conclude that, in the studied doses, oxatomide is as effective for the treatment of allergic rhinoconjunctivitis as chlorpheniramine and produces less drowsiness.

Adolescent↗
PubMed1981

Inhibition of allergen-induced asthma by three forms of sodium cromoglycate.

The effect of three forms of sodium cromoglycate (SCG), 20 mg, on allergen-induced early asthmatic responses was examined in ten stable asthmatics. Dose response allergen inhalation tests were performed on five occasions at intervals of from 1 to 2 weeks to determine the provocation concentration producing a 20% reduction (PC20 allergen) in FEV1. Placebo was given before the first and the last tests to determine the reproducibility of responses to allergen over the study period; reduced responsiveness was observed in eight of the ten subjects. Major changes in levels of specific serum antibodies of the IgE and IgG classes did not serve to explain the changes in bronchial responses although there was a trend which suggested IgG-related desensitization. The observed changes in bronchial responses and antibody levels illustrate the requirement for tests of reproducibility of responses by the use of placebo controls at the beginning and end of a series of allergen inhalation challenges. SCG as (i) a micronized powder with lactose, (ii) micropellets without lactose, or (iii) an aerosol, were inhaled double-blind, in random order, 5 min before the additional three allergen inhalation tests. PC20 allergen was reduced following SCG in seven subjects; the differences were statistically significant for the group. There was no observed difference in efficacy between the different forms of SCG. In this study, the efficacy of SCG could not be related to age, atopic status, the initial level of allergen-specific IgE antibody, baseline FEV1, level of bronchial responsiveness to inhaled histamine or an effect of SCG on responsiveness to histamine.

Adolescent↗
PubMed1981

Airway responsiveness to histamine and methacholine: relationship to minimum treatment to control symptoms of asthma.

We have prospectively examined in 51 patients the relationship between the level of airway responsiveness to histamine and methacholine and the minimum medications required to control asthma. First we determined the least medication that was required to control symptoms so that they did not disturb sleep, were not present on waking, and did not require use of inhaled salbutamol (200 microgram) more than four times daily. When baseline FEV1 was greater than 70% of predicted and when there had been no respiratory infection or allergen exposure for six weeks, histamine and methacholine inhalation tests were carried out on separate days to determine the provocation concentration causing a fall in FEV1 of 20% (PC20). There was a close correlation between the PC20 to the two agents. The patients were grouped into 1, those who required no medication; 2, those who required salbutamol (200 microgram) occasionally but not daily; 3, those who required daily salbutamol; and 4, those who required additional beclomethasone dipropionate. The mean PC20 was highest in group 1 and lowest in group 4; there was a significant difference between each group. The results indicate that airway responsiveness to vasoactive amines is either an important determinant of the severity of asthma and the medication requirements or a consequence of the severity of asthma. They raise the possibility that measurement of responsiveness may be useful in some patients with established asthma to substantiate or question medication needs.

Adolescent↗
PubMed1981

Standardization of inhalation provocation tests: two techniques of aerosol generation and inhalation compared.

Comparison of methods of aerosol generation and inhalation is required to improve standardization of inhalation provocation tests. We compared two widely used methods in 10 asthmatics, by measuring the dose and distribution of radiolabeled aerosol deposited in the throat and lung, and the provocation concentration of inhaled histamine required to reduce the FEV1 by 20% (PC20). In one method, aerosol was generated by a DeVilbiss 646 nebulizer attached to a dosimeter, and was inhaled by 5 inspiratory capacity breaths. The measurements with each method were repeated once to determine the reproducibility of results. Both methods deposited the same dose in the lung, but the distribution of the dose was different; the dosimeter method deposited more aerosol in the throat and central airways. The PC20 obtained with each method was the same. The reproducibility of all measurements in the same subject was similar. The lung dose deposited by each method in different subjects varied to the same degree. The results indicated that the bronchial response to inhaled histamine can be measured as reliably using a nebulizer and tidal breathing as by a more complex dose-metering device. They also suggested that, when the methods are regulated as described, the PC20 will have the same clinical significance.

Adolescent↗
PubMed1978

Reproducibility and comparison of responses to inhaled histamine and methacholine.

The efficiency of a standardised inhalation test procedure was studied by examining the reproducibility of responses to histamine and methacholine. In addition, the responses to the two agents were compared. Each set of duplicate tests was carried out on a separate day within one week, and all factors known or presumed to influence responses were carefully controlled. The results were expressed as the provocative concentration of the agent causing a 20% fall in forced expired volume in one second (PC20). Responses to histamine and methacholine were highly reproducible (coefficients of determination [r2] = 0.994 and 0.990 respectively). Responsiveness to histamine correlated closely with responsiveness to methacholine (r2 = 0.85). There was a small but significant cumulative dose effect with methacholine (P less than 0.01) but not with histamine. Side effects of throat irritation, flushing, and headache were more frequent with histamine than methacholine, and were dose-related. The high level of reproducibility indicates the efficiency of the test procedure. The similar severity of effects by agents with different mechanisms of action suggests that the primary cause of non-specific bronchial hyperreactivity lies at the level of bronchial smooth muscle.

Adult↗
PubMed1975

Effect of resistive loading on ventilatory response to hypoxia.

Ventilatory responses to hypoxia, with and without an inspiratory resistive load, were measured in eight normal subjects, using a rebreathing technique. During the studies, the end-tidal P-CO2 was kept constant at mixed venous level (Pv-CO2) by drawing expired gas through a variable CO2-absorbing bypass. The initial bag O2 concentration was 24% and rebreathing was continued until the O2 concentration in the bag fell to 6% or the subject's arterial oxygen saturation (Sa-O2), monitored continuously by ear oximetry, fell to 70%. Studies with and without the load were performed in a formally randomized order for each subject. Linear regressions for rise in ventilation against fall in Sa-O2 were calculated. The range of unloaded responses was 0.78-3.59 1/min per 1% fall in Sa-O2 and loaded responses 0.37-1.68 1/min per 1% fall in Sa-O2. In each subject, the slope of the response curve during loading fell by an almost constant fraction of the unloaded response, such that the ratio of loaded to unloaded slope in all subjects ranged from 0.41 to 0.48. However, the extrapolated intercept of the response curve on the Sa-O2 axis did not alter significantly indicating that the P-CO2 did not alter between experiments. These results suggest that the change in ventilatory response to hypoxia during inspiratory resistive loading is related to the mechanical load applied, with the loaded slope being directly proportional to the unloaded one.

Adult↗
PubMedDate not supplied

Effect of asthma on quality of life.

Physicians now recognize the importance and usefulness of incorporating an assessment of health-related quality of life (HRQL) in their clinical practice and clinical studies. Conventional measurements provide useful information about airway status but provide little information about functional impairments that are important in a patient's everyday life. This paper outlines the concept of HRQL and explains the importance of the concept for treating asthma patients. The paper also describes several questionnaires for measuring HRQL, including athma-specific quality of life instruments, and discusses how to select an appropriate HRQL instrument.

Adult↗