PubMed Health⌕ Search

Biomedical subjects

M R Sears

Publications and source records attributed to M R Sears.

At least 19 recordsLinked to original sources
PubMed1992

The effects of airway hyperresponsiveness, wheezing, and atopy on longitudinal pulmonary function in children: a 6-year follow-up study.

We examined growth of spirometric lung function in 696 children of European ancestry who were followed from ages 9 to 15 years and stratified according to their degree of responsiveness to methacholine inhalation challenge, atopic status, and respiratory symptoms. Subjects were participants in the longitudinal Multidisciplinary Health and Development Study in Dunedin, New Zealand. Forced expired volume in 1 second (FEV1), and vital capacity (VC) were measured at 9, 11, 13, and 15 years of age, concurrently with assessment of airway responsiveness determined by the concentration of methacholine causing a 20% fall in FEV1 (PC20 FEV1). Atopic status was assessed at age 13 by skin-prick testing to 11 allergens. In children demonstrating airway hyperresponsiveness, FEV1 increased with age at a slower rate, and the FEV1/VC ratio had a faster rate of decline through childhood, compared to non-responsive children. Subjects with positive skin tests to house dust mite and cat dander also had lower mean FEV1/VC ratios than the control group. Any reported wheezing was associated with slower growth of FEV1 and VC in males. We conclude that in New Zealand children with airway responsiveness and/or atopy to house dust mite or cat growth of spirometric lung function is impaired.

Adolescent↗
PubMed1992

Relationships of bronchial responsiveness assessed by methacholine to serum IgE, lung function, symptoms, and diagnoses in 11-year-old New Zealand children.

The relationship of bronchial responsiveness (BR), assessed by methacholine challenge, to serum IgE, baseline ventilatory function, and symptoms or diagnoses suggesting an atopic disorder were examined in 522 11-year-old New Zealand children. BR was assessed by the presence or absence of a PC20 25 mg/ml or less and by calculating a continuous index of the decline of the FEV1 during the methacholine test. The latter facilitated multivariate analyses and revealed significant relationships to predictor variables even in those considered "nonresponsive" by PC20 criteria. There was a close relationship of BR to the baseline FEV1/vital capacity ratio, seen even in patients with known asthma, but this relationship was seen only in subjects with at least moderate levels of serum IgE. There was a less close relation of BR to percent predicted FEV1, but this persisted even after accounting for the FEV1/vital capacity ratio and was present regardless of the level of serum IgE. Reported asthma was associated with increased BR independent of all other factors, but other diagnoses and symptoms contributed relatively little to the prediction of BR once the serum IgE and lung function were taken into account. The overall results are compatible with the concept that IgE is a critical factor in the development of bronchial responsiveness in childhood.

Asthma↗
PubMed1992

Longitudinal effects of passive smoking on pulmonary function in New Zealand children.

In this study we examined the longitudinal effects of smoke exposure on lung function in a cohort of New Zealand children observed from 9 to 15 yr of age. Possible exposures included in utero exposure from mothers smoking during pregnancy, passive smoke from parents, and active smoking by the children. Lung function measures of forced expiratory volume in one second (FEV1) and vital capacity (VC) were measured biennially and ratios (FEV1/VC) were computed. The data were analyzed using longitudinal methodology, and all subjects with at least one pulmonary function test and responses to the questions concerning smoke exposures were included (n = 634). Subjects reporting wheeze or asthma were examined as a separate subgroup. In the whole cohort, no significant detrimental effects were detected for absolute FEV1 or VC in either sex, related to active or passive smoke exposures. Parental smoking was, however, associated with persistent but mild and nonprogressive impairment of the FEV1/VC ratio in males, an effect that was present at the time lung function measurements were first made. This effect was not seen in females. In children with reported wheeze or asthma, parental smoking had progressive, more serious, and clinically significant effects on the FEV1/VC ratio among adolescents of both sexes, causing a mean reduction in FEV1/VC ratios by age 15 of 3.9% in males and 2.3% in females, in contrast to the observed increase in FEV1/VC ratios with age seen in nonexposed wheezing children. We conclude that passive smoking is a major contributing factor to the development and persistence of airflow limitation in wheezing children.

Adolescent↗
PubMed1992

Increased inhaled bronchodilator vs increased inhaled corticosteroid in the control of moderate asthma.

Undertreatment of chronic asthma may reflect uncertainty as to how it may be best controlled. We compared the effects of increased inhaled corticosteroid vs regular inhaled bronchodilator in 32 adult asthmatics. During three 16-week treatment periods, comprising baseline inhaled corticosteroid (mean 505 micrograms daily) and on-demand beta-agonist, baseline inhaled corticosteroid and increased (regularly scheduled four times daily) beta-agonist, and increased inhaled corticosteroid (mean 1478 micrograms daily) and on-demand beta-agonist, subjects recorded symptoms, morning and evening peak flow, and additional medication. Of 25 subjects whose control differed significantly between treatments with baseline vs increased corticosteroid, 22 (88 percent) favored the increased dosage (p < 0.001). Of 28 subjects whose control differed between treatments with regular beta-agonist vs increased corticosteroid, 24 (86 percent) were better controlled with increased inhaled corticosteroid and were worse with regular beta-agonist (p < 0.001). Only one quarter the number of exacerbations were experienced during treatment with increased inhaled corticosteroid. Upper airway adverse effects were minor and easily controlled. Hence, asthma with persistent symptoms was better controlled by increased inhaled corticosteroid therapy than by increased use of inhaled beta-agonist.

Administration, Inhalation↗
PubMed1991

Relation between airway responsiveness and serum IgE in children with asthma and in apparently normal children.

BACKGROUND: Although asthma diagnosed by a physician is known to be related to serum IgE levels, it is not known whether there is a relation between the level of IgE and airway hyperresponsiveness to a methacholine challenge. The characteristics of asymptomatic persons that predispose them to airway hyperresponsiveness are also unknown. METHODS: We studied the relation between the serum total IgE level and airway hyperresponsiveness in the presence or absence of asthma and other atopic diseases in a birth cohort of children. Data from a questionnaire regarding respiratory symptoms, plus measurements of the serum total IgE level and airway responsiveness to inhaled methacholine, were obtained for 562 11-year-olds in New Zealand. RESULTS: The boys had a higher prevalence than the girls of current diagnosed asthma (13 percent vs. 6 percent), current symptoms of wheezing (22 percent vs. 15 percent), and airflow obstruction at base line (6 percent vs. 1 percent) and had a wider distribution of IgE levels, although mean IgE levels (120.8 IU per milliliter in the boys and 98.1 IU per milliliter in the girls) did not differ significantly between the sexes. The prevalence of diagnosed asthma was strongly related to the serum IgE level (P for trend less than 0.0001). No asthma was reported in children with IgE levels less than 32 IU per milliliter, whereas 36 percent of those with IgE levels greater than or equal to 1000 IU per milliliter were reported to have asthma. This relation with the serum IgE level was not explained by a concomitant diagnosis of allergic rhinitis or eczema. Airway hyperresponsiveness to a methacholine challenge also correlated very highly (P less than 0.0001) with the serum IgE level. This relation remained significant even after the exclusion of children with diagnosed asthma (P less than 0.0001) and of all children with a history of wheezing, allergic rhinitis, or eczema (P less than 0.0001). CONCLUSIONS: Even in children who have been asymptomatic throughout their lives and have no history of atopic disease, airway hyperresponsiveness appears to be closely linked to an allergic diathesis, as reflected by the serum total IgE level.

Asthma↗
PubMed1991

Handedness and allergic disorders in a New Zealand cohort.

Studies of the proposed association between handedness and allergic disorders have shown results which appear contradictory. In view of differences in the procedures of these studies, further tests of the strength of this association are warranted. Results from this study of a large birth cohort of children showed no support for an association between handedness measured at age 7 years and reports of eczema, urticaria, rhinitis, or asthma in late childhood or early adolescence. There was no significant association found between handedness and reported frequency and duration of symptoms of wheezing, or parental help-seeking for these symptoms. Apparent differences in the results of these studies could possibly be reconciled by the view that preference for use of the left hand may be associated with increased help-seeking behaviour in later life for a range of problems or difficulties. Further tests of the association between handedness and disorder in clinical samples require more rigorous control procedures.

Adolescent↗
PubMed1990

Regular inhaled beta-agonist treatment in bronchial asthma.

89 subjects with stable asthma took part in a double-blind, placebo-controlled, randomized, crossover study of the effects of regular versus on-demand inhaled bronchodilator therapy. The subjects inhaled fenoterol or placebo by a dry powder delivery system for 24 weeks. Control of asthma was judged by daily morning and evening peak expiratory flow rates, symptom diaries, use of additional inhaled bronchodilator, and requirement for short courses of prednisone. Of 64 subjects who completed the trial, 57 showed a clear difference in degree of control of asthma between the fenoterol and placebo periods: in 17 (30% [95% confidence interval 18.4-43.4%]) asthma was better controlled during regular inhaled bronchodilator treatment, whereas in 40 (70% [56.6-81.6%]) control was better during placebo treatment with bronchodilator for symptom relief only. Mean airway responsiveness to methacholine increased slightly during the fenoterol period. The adverse effect of regular bronchodilator inhalation occurred not only among subjects who used a bronchodilator as sole treatment (2 were better and 10 were worse during regular bronchodilator treatment) but also among those who took inhaled corticosteroids (14 were better and 29 were worse). Thus, regular inhalation of a beta-sympathomimetic agent was associated with deterioration of asthma control in the majority of subjects. The trends to use of regular, higher doses or longer-acting inhaled beta-sympathomimetic treatment may be an important causal factor in the worldwide increase in morbidity from asthma.

Administration, Inhalation↗