Search PubMed⌕ Search

Biomedical subjects

G Boyd

Publications and source records attributed to G Boyd.

At least 91 records · Page 5Linked to original sources
PubMed1985

Twice or four times daily beclomethasone dipropionate in mild stable asthma?

A double-blind cross-over study lasting 16 weeks was conducted to establish if a twice daily regimen of beclomethasone dipropionate (BDP) was as effective in controlling asthma as a four times daily regimen. The patient's need for inhaled steroids (100 mcg BDP qds) was confirmed prior to entering the study by deterioration of peak expiratory flow rates and/or increased bronchodilator usage during a single-blind placebo period of 6 weeks. Thirty six asthmatics were eligible to enter the study and completed both treatment periods. Daily record cards of symptom scores, four times daily peak expiratory flow rate measurements and inhaled bronchodilator usage were recorded throughout the study. There was no significant difference between the mean PEFR measurements taken four times each day and the variability in PEFR, between the two treatment groups. Symptom scores for cough, wheeze, breathlessness and overall disability also showed no significant difference. Symptomatic inhaler usage for the two groups was similar. Lung function measurements of FEV1, FVC and VC were almost identical; FEV1 being 2.1 l on twice daily regimen and 2.2 l on four times daily regimen. A slight variation was observed in PEFR taken at the end of each treatment period at the clinic visits, being 361 l/min on twice daily and 380 l/min on four times daily drug dosage. In stable asthmatics, the control of asthma measured both symptomatically and by daily lung function was independent of dosing schedule, but twice daily treatment may well lead to better compliance.

Adult↗
PubMed1984

Factors influencing the occurrence of a late reaction to allergen challenge in atopic asthmatics.

Thirty extrinsic asthmatics were challenged by inhalation with Dermatophagoides pteronyssinus extract. In twenty-four an immediate reaction was observed and in sixteen this was followed by a late reaction. Those with late reactions tended to have more severe asthma but did not report greater sensitivity to housedust mite. The occurrence of a late reaction was not related to the degree of airways obstruction before challenge or to the intensity of the immediate reaction. Patients in whom the early reaction was induced by a low dose of inhaled antigen were those most likely to develop a late response. Results of histamine challenge testing suggested that this greater sensitivity of the airway might in part be due to greater non-specific bronchial reactivity.

Adolescent↗
PubMed1984

Antibody measurement in extrinsic allergic alveolitis.

Serum IgG antibody against purified avian antigens was quantified by radioimmunoassay in 507 active pigeon fanciers, of whom 110 had documented Pigeon Breeders Disease (PBD). The incidence of PBD increased from 3.7% in the antibody-negative group to 78% of those with IgG antibody greater than 30 micrograms/ml. The highest levels of antibody tended to occur in subjects with relatively short avian exposure, and a significant correlation between decreasing antibody levels and increasing years of avian contact was demonstrated, which was unrelated to age or smoking history. The antibody -positive subjects had lower daily hours of avian contact and this group which contained most of the PBD subjects demonstrated some self-regulation of antigen exposure.

Age Factors↗
PubMed1983

Site of airflow obstruction in immediate and late reactions to bronchial challenge with Dermatophagoides pteronyssinus.

The density dependence of maximum flow in ten atopic asthmatics was assessed by response to breathing a helium-oxygen mixture. They were then subjected to bronchial challenge by Dermatophagoides pteronyssinus and density dependence re-assessed during early and late bronchial reactions. There was considerable individual variation in the density dependence before challenge and in the change in density dependence during induced bronchospasm. However, for any given individual the results were similar during early and late reactions. This suggests that the major site of airflow obstruction may vary from one asthmatic to another but that when antigen challenge is followed by a dual early and late reaction the site of obstruction is similar at each stage.

Adolescent↗
PubMed1983

Seasonal variation of antibody levels among pigeon fanciers.

IgG antibody against avian antigens was measured by quantitative radioimmunoassay in serum samples obtained regularly from twenty pigeon fanciers over a 1-year period. A seasonal variation was seen in nine antibody-positive subjects; eight of whom had symptoms of pigeon breeder's disease (PBD), and a clear peak of antibody production occurred during late summer, corresponding with the period of maximum avian contact in the sporting season. All subjects with insignificant specific IgG levels were asymptomatic and displayed minimal changes throughout the year despite a similar exposure pattern to antigen for all individuals. Raised total IgG was a feature of six symptomatic subjects, two of whom had raised total IgA. Three of these six subjects had maximum hypergamma-globulinaemia coinciding with peak specific-antibody levels, but in general the total immunoglobulin levels tended to remain high throughout the year with only marginal fluctuations. The total immunoglobulin levels in the other individuals were within normal limits and displayed no remarkable changes during the year. The subjects with pigeon breeder's disease had a more active immune responsiveness to avian contact, and the association of the highest levels with periods of maximal contact with antigen may have an important bearing on the dynamic nature of this condition.

Adult↗
PubMed1983

Skin testing and extrinsic allergic alveolitis.

Skin testing with six common allergens, tuberculin and a sterile avian antigen preparation from pigeon serum was performed on 102 pigeon fanciers. The incidence of positive prick tests to common allergens was no different for subjects with extrinsic allergic alveolitis. EAA, caused by avian exposure than the whole group. Positive immediate weal and flare reactions following skin prick testing with avian antigen occurred in 22 subjects and was closely correlated with atopy. However, when the same antigen was administered intradermally, 69 subjects developed an immediate (15 min) weal and flare reaction which did not correlate with atopy, instead, the weal diameter correlated significantly with the serum IgG antibody titre against pigeon serum gamma-globulin antigen, and furthermore, the higher grades of reaction were highly selective for subjects with EAA. Ten subjects, all with strong early intradermal skin reactions, developed a late (4-6 h) skin reaction; this was again highly selective for EAA. The subjects with cutaneous anergy to tuberculin had markedly higher IgG antibody titres to avian antigens, and these included the majority of the subjects with alveolitis.

Allergens↗
PubMed1982

Antibody against a pigeon bloom-extract: a further antigen in pigeon fanciers' lung.

Pigeon bloom, a waxy powder which coats the feathers of racing pigeons, has been investigated as a potential antigen in pigeon fanciers' lung. Precipitins to a soluble bloom-extract were demonstrated in fifty-nine of ninety-seven people studied at two Scottish-pigeon shows, whilst precipitins to pigeon serum were found in thirty-seven. A radioimmunoassay was developed to allow an estimation of the intensity of antibody response to this antigen in nineteen pigeon fanciers being investigated for pigeon fanciers' lung. The mean antibody level to bloom extract was significantly higher (P less than 0.05) in those with acute symptoms compared to those with less severe symptoms. Pigeon bloom is a highly antigenic material and provides an alternative to pigeon droppings as a source for the inhalant antigens regularly encountered by those keeping pigeons.

Alveolitis, Extrinsic Allergic↗