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Biomedical subjects

A Woolcock

Publications and source records attributed to A Woolcock.

17 recordsLinked to original sources
PubMed1999

Differences between asthma exacerbations and poor asthma control.

BACKGROUND: Increased variation in peak expiratory flow (PEF) is characteristic of poorly controlled asthma, and measurement of diurnal variability of PEF has been recommended for assessment of asthma severity, including during exacerbations. We aimed to test whether asthma exacerbations had the same PEF characteristics as poor asthma control. METHODS: Electronic PEF records from 43 patients with initially poorly controlled asthma were examined for all exacerbations that occurred after PEF reached a plateau with inhaled corticosteroid treatment. Diurnal variability of PEF was compared during exacerbations, run-in (poor asthma control), and the period of stable asthma before each exacerbation. FINDINGS: Diurnal variability was 21.3% during poor asthma control and improved to 5.3% (stable asthma) with inhaled corticosteroid treatment. 40 exacerbations occurred in 26 patients over 2-16 months; 38 (95%) of exacerbations were associated with symptoms of clinical respiratory infection. During exacerbations, consecutive PEF values fell linearly over several days then improved linearly. However, diurnal variability during exacerbations (7.7%) was not significantly higher than during stable asthma (5.4%, p=0.1). PEF data were consistent with impaired response to inhaled beta2-agonist during exacerbations but not during poorly controlled asthma. INTERPRETATION: Asthmatics remain vulnerable to exacerbations during clinical respiratory infections, even after asthma is brought under control. Calculation of diurnal variability may fail to detect important changes in lung function. PEF variation is strikingly different during exacerbations compared with poor asthma control, suggesting differences in beta2-adrenoceptor function between these conditions.

Adolescent↗
PubMed1996

Comparison of addition of salmeterol to inhaled steroids with doubling of the dose of inhaled steroids.

A study was done to compare the efficacy and safety of the coprescription of salmeterol 50 microgram twice daily or 100 microgram twice daily with beclomethasone dipropionate (BDP) 500 micrograms twice daily (SALM 50 and SALM 100) with BDP 1,000 microgram twice daily (BDP 1,000) in patients with asthma not controlled by BDP 500 microgram twice daily (or the equivalent). Following a run-in period, 738 patients at 72 centers were randomized to treatment for 24 wk in a double-blind, parallel-group study during which they maintained a daily record of peak expiratory flow rates (PEFRs) and symptom scores. At about 40 of the centers, bronchial hyperresponsiveness (BHR) to histamine was measured during and at 3 and 14 d after stopping treatment. Both groups taking salmeterol showed an improvement of more than 45 L/min in their morning PEFR and 30 L/min in their evening PEFR, compared with respective improvements of 16 L/min and 6 L/min in the group taking BDP 1,000. Both the SALM 50 and SALM 100 groups had a significantly increased percentage of symptom-free and rescue-free days and nights compared with the BDP 1,000 group, and there was no difference between the two salmeterol groups. None of the treatments altered BHR. Exacerbation rates did not differ among the three groups. We conclude that in this selected group of symptomatic patients taking BDP 500 micrograms twice daily, the addition of salmeterol provides better improvement in lung function and symptom control, without altering BHR or increasing exacerbation rates, than does doubling the dose of BDP.

Administration, Inhalation↗
PubMed1992

Changes in mite allergen Der p I in house dust following spraying with a tannic acid/acaricide solution.

The beds, carpets and furnishings in 15 houses were sprayed with a solution containing tannic acid and an acaricide in an attempt to reduce allergen concentrations. Dust was collected from these sites for 4 weeks following spraying and the mite allergen Der p I concentration was measured and compared with baseline concentrations. In a subgroup of houses, counts of live mites and estimates of aeroallergen were also made. Four untreated houses were monitored over the same period. In dust samples collected 3 days after spraying, the mean concentrations of Der p I in beds, carpets and furniture were 23%, 28% and 26% of the pretreatment levels. All these reductions were significant compared to untreated controls. Samples collected 4 weeks after treatment were not significantly different to baseline for each group. After the initial reduction, the rate of increase in allergen concentration was significantly greater in the spray-only beds than in the beds which had been both sprayed and fitted with occlusive covers. Both aeroallergen and live mites continued to be detected in houses after treatment with the spray. These studies suggest that such sprays are only temporarily effective when applied at the manufacturer's recommended volumes and additional approaches are required to control the bulk of allergens in houses.

Allergens↗
PubMed1991

A review of the racial differences in the lung function of normal Caucasian, Chinese and Indian subjects.

In the clinic, predicted normal values are widely used for routine assessments and, therefore, it is important that the noted differences in lung volumes between the races are recognized. Further epidemiological studies, using comparative methods and standard statistical techniques, are essential in order to quantify apparent differences between the races and to standardize normal values for race, especially with regard to age, with greater accuracy.

Adult↗
PubMed1989

Absence of immunoreactive vasoactive intestinal polypeptide in tissue from the lungs of patients with asthma.

Vasoactive intestinal polypeptide (VIP) is a neuropeptide present in the nerve fibers of normal lungs, where it acts to relax bronchial smooth muscle. To determine its presence or absence in the lungs of patients with asthma, we examined lung tissue obtained at autopsy or lobectomy from five patients with asthma and nine without asthma. The avidin-biotin-peroxidase complex technique was used to stain tissue for immunoreactivity to VIP. At least 80 tissue sections from each patient were examined microscopically; the airway diameter ranged from 100 microns to 1.2 cm. Immunoreactive VIP was seen within nerves in more than 92 percent of the sections from the lungs of patients without asthma. No VIP was seen in any of 468 sections we could evaluate that were obtained from the lungs of patients with asthma. As a control for the nonspecific destruction of neuropeptides, immunostaining for substance P was also carried out. Abundant amounts of this neuropeptide were seen within nerves in tissue from the lungs of all patients. We conclude that in patients with asthma there is a loss of VIP from the pulmonary nerve fibers that may diminish neurogenically mediated bronchodilation. Whether this loss is a cause or a result of asthma is unclear.

Adolescent↗
PubMed1988

Comparison of the effects of nebulized terbutaline with intravenous enprofylline in patients with acute asthma.

We compared the bronchodilating effects of intravenously administered enprofylline (2 mg/kg) with nebulized terbutaline (10 mg) in patients presenting to hospital with acute asthma in a multicenter double-blind parallel study. One hundred twenty three patients were randomized into the study, and 69 of these fulfilled the inclusion criteria and a retrospective time to study entry criterion; 34 received enprofylline and 35 received terbutaline. There was no significant difference in maximum increase in forced expired volume in 1 second (FEV1) between the enprofylline group (0.24 +/- 0.33 L) and the terbutaline group (0.25 +/- 0.28 L) (p greater than 0.05), nor for the increase in FEV1 over the 1-hour study period. Tremor was reported more in the group receiving terbutaline, and nausea was reported more in the group receiving enprofylline. Two patients experienced hypotension and one patient had a vasovagal episode with enprofylline treatment. Both agents acted as bronchodilators with similar efficacy in patients with acute asthma in this study.

Acute Disease↗
PubMed1984

Airflow limitation.

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Airway Obstruction↗