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Biomedical subjects

D S Postma

Publications and source records attributed to D S Postma.

At least 217 records · Page 12Linked to original sources
PubMed1996

Seasonal variations in house dust mite influence the circadian peak expiratory flow amplitude.

The aim of the study was to investigate whether seasonal differences in house dust mite (HDM) allergen exposure influence the circadian peak expiratory flow (PEF) amplitude in asthmatic children. Asthmatic children (n = 25) with a solitary allergy to HDM were studied in spring and in autumn. All used inhaled corticosteroids (ICS) regularly. Six days after withdrawal of ICS, PEF amplitude (every 4 h during 24 h, highest-lowest/percentage of mean value) was assessed. HDM allergen (HDMA) in living rooms, bedrooms, and mattresses was collected. HDMA levels were not always highest in autumn. PEF amplitudes in spring and autumn did not correlate with HDMA levels in the same season. However, the seasonal difference in PEF amplitude (autumn value - spring value) correlated positively and significantly with the seasonal difference in HDMA exposure levels from the mattresses (rho = 0.34, p < 0.05). Multivariate analysis showed that the seasonal difference in HDMA exposure in the mattress was the single parameter explaining seasonal difference in PEF amplitudes by 21.0% (p = 0.02). Our cross-sectional study showed a higher PEF amplitude not to be significantly associated with higher HDMA exposure in mattresses in a group of HDM-allergic asthmatic children. However, the change in HDMA exposure over seasons contributed significantly to the change in PEF amplitude after withdrawal of ICS in HDM-allergic asthmatic children.

Allergens↗
PubMed1996

Risk factors for accelerated decline among patients with chronic obstructive pulmonary disease.

The interpretation of studies of decline of FEV1 in patients with established COPD is complicated by many methodologic problems, such as retrospective analyses, small patient groups, different patient selection, and differences in the mathematical models used. Nevertheless, it is clear that the rate of loss of lung function is above all determined by the smoking status and history. A more abnormal bronchoconstrictor response is predictive of a steeper decline of lung function. Other prognostic factors have not been consistently found in patients with established disease. The decline can be influenced favorably by smoking cessation, and probably by oxygen administration in hypoxemic patients. Long-term oral steroid use seems to be associated with a more favorable course of FEV1, but the value of inhaled corticosteroids has not yet been established. Maintenance therapy with bronchodilators only does not appear to improve the decline of FEV1.

Adult↗
PubMed1996

Ultrastructural immunogold localization of interleukin 5 to the crystalloid core compartment of eosinophil secondary granules in patients with atopic asthma.

Bronchial biopsies from two patients with atopic asthma were analyzed by immunogold labeling to detect the ultrastructural location of interleukin 5 (IL-5). In eosinophils, IL-5 was localized to the electron-dense crystalloid core compartment of the secondary or specific eosinophil granules. Other structures in the eosinophils were unlabeled. No IL-5 was detected in mast cells. Control sections incubated with an irrelevant primary antibody were negative. This study demonstrates that pre-formed IL-5 is stored within the major population of secondary granules in human eosinophils.

Asthma↗
PubMed1996

Effects of home rehabilitation on physical performance in patients with chronic obstructive pulmonary disease (COPD).

We investigated whether 12 weeks of rehabilitation at home in patients with chronic obstructive pulmonary disease (COPD) had a beneficial effect on lactate production, metabolic gas exchange data, workload of the inspiratory muscles, and dyspnoea during a maximal bicycle ergometer test. A second aim was to assess whether a change in dyspnoea was related to a change of inspiratory muscle workload. Forty three COPD patients with severe airways obstruction were included in the study: mean forced expiratory volume in one second (FEV1) 1.3 +/- 0.4 L (44% predicted), mean FEV1/inspiratory vital capacity (IVC) 37 +/- 8%. Twenty eight patients started a rehabilitation programme, whilst 15 patients received no rehabilitation. Rehabilitation was carried out at home; patients were supervised by a general practitioner, a physiotherapist and a nurse. Exercise tolerance was measured by means of a 6 min walking distance test (6MWD) and maximal workload (Wmax) during an incremental symptom-limited cycle ergometer test. Inspiratory muscle workload at Wmax was assessed with the Tension Time Index (TTI), and dyspnoea at Wmax with the Borg scale. After 12 weeks, the rehabilitation group showed a significantly larger increase in 6MWD (from 438 to 447 m) and in Wmax (from 70 to 78 W) compared with the control group. A significant improvement in oxygen consumption (V1O2) (from 1.0 to 1.1 L), lactate level (from 3.7 to 3.1 mEq.L(-1)), dyspnoea (from 6.0 to 4.5) and TTI (from 0.10 to 0.08) at Wmax occurred in the rehabilitation group during the programme. The reduction in TTI was not significantly correlated with the fall in dyspnoea, as assessed by the Borg scale. We conclude that 12 weeks of rehabilitation at home in COPD patients increases symptom-limited V1O2 in combination with an increased Wmax. At this significantly higher Wmax, there was a reduction in dyspnoea, lactate level and inspiratory muscle workload. The reduction in dyspnoea was not related to a decreased inspiratory muscle workload. This study shows that rehabilitation at home can produce beneficial physiological improvements during exercise in patients with chronic obstructive pulmonary disease.

Aged↗
PubMed1996

A comparison between an outpatient hospital-based pulmonary rehabilitation program and a home-care pulmonary rehabilitation program in patients with COPD. A follow-up of 18 months.

AIM: In this study, the effects of a 12-week hospital-based outpatient pulmonary rehabilitation program (HRP) are compared with those of a 12-week home-care rehabilitation program (HCRP) in COPD patients. A control group received no rehabilitation therapy. METHODS: After randomization and stratification, effects on lung function, exercise performance (4-min walking test and cycle ergometer test), dyspnea, and leg effort during exercise, and well-being were assessed in 45 COPD patients with moderate to severe airflow limitation (mean [SD] FEV1 percent predicted, 42.8 [8.4]). RESULTS: After HRP and HCRP, at 3 to 6 months after the start of the study, equal improvements were detected in exercise capacity and in Borg dyspnea and leg effort scores at similar work levels during the cycle test. However, whereas after HRP at longer term values tended to return to baseline outcome, after HCRP a further ongoing significant improvement in exercise capacity was observed, while Borg dyspnea scores remained significantly improved over 18 months. Improvements in cycle workload and dyspnea score were significantly better maintained after HCRP as compared with HRP. Lung function, arterial oxygen saturation, and heart frequency during exercise did not change. A significant improvement in well-being was maintained over 18 months in both rehabilitation groups. CONCLUSION: Beneficial effects are achieved both after a HRP and a HCRP in COPD patients with moderate to severe airflow limitation. Yet we recommend to initiate HCRPs as improvements are maintained longer and are even further strengthened in this setting.

Aged↗
PubMed1996

Effects of long-term treatment with corticosteroids in COPD.

STUDY OBJECTIVE: To determine the effectiveness of treatment with corticosteroids in patients with COPD. METHODS: In this study, we investigated the effect of a 2-year treatment with corticosteroids on clinical symptoms and the decline of lung function in 58 nonallergic patients with COPD. Subjects were treated in a double-blind, randomized, placebo-controlled, parallel way with inhaled budesonide (bud), 1,600 micrograms/d; inhaled budesonide, 1,600 micrograms/d, plus oral prednisolone, 5 micrograms/d (bud + pred); or placebo (plac). Clinical assessment (history, physical examination, and spirometry) was carried out every 2 months. The rate of decline in FEV1 was assessed by calculating individual regression co-efficients from linear regression of FEV1 on time for each subject. RESULTS: Eleven patients dropped out. The number of withdrawals due to pulmonary problems was significantly higher in the plac group (n = 5 out of 18) than in the actively treated groups (n = 2 out of 40). Treatment with corticosteroids significantly reduced pulmonary symptoms. Median decline of FEV1 was 60 mL/yr in the plac group, 40 mL/yr in the bud + pred group, and 30 mL/yr in the bud group. Variation was large and differences were not statistically significant. No treatment effect was found on frequency or duration of exacerbations, possibly because of the high number of withdrawals due to pulmonary deterioration in the plac group. Treatment with a combination of inhaled plus oral corticosteroids was not more effective than inhaled corticosteroids alone. Morning plasma cortisol levels remained within the normal range in all three groups. CONCLUSIONS: Our study shows beneficial effects of long-term daily treatment with inhaled corticosteroids in patients with COPD with regard to symptoms and drop out due to pulmonary problems. Lung function decline tends to decrease during treatment with inhaled corticosteroids. The observed effects are limited but warrant further studies on the effectiveness of corticosteroids in larger numbers of patients with COPD.

Administration, Inhalation↗
PubMed1996

Is delayed introduction of inhaled corticosteroids harmful in patients with obstructive airways disease (asthma and COPD)? The Dutch CNSLD Study Group. The Dutch Chronic Nonspecific Lung Disease Study Groups.

BACKGROUND: The institution of inhaled corticosteroids is generally advocated for effective treatment of patients with asthma. It is yet unknown what is the best time to start inhaled corticosteroid therapy and especially whether delayed introduction is harmful. PHASE 1: In a previous study in patients with asthma and COPD, we found that 2.5 years of treatment with a beta 2-agonist plus inhaled corticosteroid (BA + CS) was more effective in improving the FEV1 and the provocative concentration of histamine causing a 20% reduction in FEV1 (PC20) than treatment with a beta 2-agonist plus anticholinergic (BA + AC) or placebo (BA + PL). PHASE 2: We extended this study with 6 months to investigate whether delayed introduction of inhaled CS therapy (800 micrograms beclomethasone dipropionate) in the groups previously not treated with inhaled CS (BA +/- AC) could also improve FEV1 and PC20 to the same degree. A distinction was made between patients with predominantly asthma (high baseline reversibility, delta FEV1 > or = 9% of predicted), and predominantly COPD (low baseline reversibility, delta FEV1 < 9% of predicted). RESULTS: Improvement of FEV1 percent predicted by inhaled CS was comparable both in the asthmatics between phase 1 (13.8% predicted) and phase 2 (8.5% predicted; p = 0.31) as well as in the patients with COPD (2.5% and 1.5% predicted, respectively). PC20, however, increased significantly more in the asthmatics in phase 1 (1.77 doubling concentration [DC]) than in phase 2 (0.79 DC; p = 0.03). Improvement of PC20 in the patients with COPD was not significantly higher in phase 1 (0.74 DC) than in phase 2 (0.00 DC; p = 0.19). CONCLUSIONS: Our study indicates that although delayed introduction of inhaled CS in asthmatics leads to similar improvements in FEV1, improvements in PC20 are significantly less. These findings in patients with longer-existing asthma concur with other findings in newly detected asthma. We suggest that institution of inhaled CS therapy should not be postponed in asthmatics with documented airways obstruction and reversibility.

Administration, Inhalation↗
PubMed1996

Activation of the cAMP-dependent signaling pathway downregulates the expression of interleukin-3 and granulocyte-macrophage colony-stimulating factor in activated human T lymphocytes.

Expression of cytokines by T lymphocytes is a highly balanced process, involving stimulatory and inhibitory intracellular signaling pathways. We have examined the modulating effects of the cAMP-dependent signaling pathway on the expression of interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in activated human T lymphocytes. 2'-O-dibutyryl-cAMP (db-cAMP), prostaglandin E2 (PGE2), isoproterenol (ISO), and isobutyl-methyl-xantin (IBMX) costimulated with concanavalin A (Con A) or Con A plus the phorbolester phorbol myristate acetate (PMA) inhibited IL-3 and GM-CSF mRNA accumulation compared to the effects of Con A or Con A plus PMA alone. Nuclear run-on experiments revealed that the inhibitory effect of db-cAMP could partially be ascribed to a five-fold reduction in transcription rate of both the IL-3 and GM-CSF gene in the presence of Con A or Con A plus PMA. mRNA stability studies demonstrated that PMA increased the stability of both transcripts. db-cAMP did not affect the stability of IL-3 and GM-CSF mRNAs in Con A activated cells. In contrast, in Con A plus PMA activated cells, db-cAMP significantly reduced the half-life of both transcripts: IL-3 >240 minutes vs. 90 minutes and GM-CSF 90 minutes vs. 60 minutes. Finally, in accordance with the mRNA data, db-cAMP, PGE2, and ISO reduced the secretion of IL-3 and GM-CSF protein in Con A and Con A plus PMA activated cells. In conclusion, these data demonstrate that the protein kinase A (PKA)-dependent signaling pathway is an important regulatory mechanism in controlling IL-3 and GM-CSF gene expression in activated human T lymphocytes.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Increased numbers of dendritic cells in the bronchial mucosa of atopic asthmatic patients: downregulation by inhaled corticosteroids.

BACKGROUND: Dendritic cells (DC) are the most potent antigen-presenting cells (APC) and stimulators of T cells. Dendritic cells are also likely to be essential for the initiation of allergic immune responses in the lung. However, there are not many data on the presence of dendritic cells in the airways of patients with atopic asthma and on the effects of corticosteroid-treatment on such dendritic cells. OBJECTIVE: We investigated the distribution of dendritic cells in the bronchial epithelium and mucosa of 16 non-smoking atopic asthmatic patients and eight healthy control subjects using detailed immunohistochemistry (CD1a, HLA-DR, L25 as markers for dendritic cells). METHODS: Eleven asthmatics were treated for 2.5 years with bronchodilators only and five with bronchodilators and inhaled beclomethasone dipropionate (BDP), 800 micrograms daily. The patients were randomly sampled from a double-blind multicentre study. RESULTS: There were higher numbers of CD1a+ DC (P = 0.003), L25+ DC (P = 0.002) and HLA-DR expression (P = 0.042) in the bronchial mucosa of asthmatic patients compared with healthy controls. After 2.5 years of treatment, we found a significant increase in flow expiratory volume in 1 second (FEV1) (P = 0.009) and a significant decrease in hyperresponsiveness (PC20 histamine) (P = 0.013) in the corticosteroid group (n = 5) compared with the bronchodilator group (n = 11). This clinical improvement in the corticosteroid-treated group was accompanied by significantly lower numbers of CD1a+ DC (P = 0.008), and HLA-DR expression (P = 0.028) in the bronchial mucosa than in the bronchodilator-treated group. CONCLUSION: Our data suggest that dendritic cells are involved in asthmatic inflammation and that corticosteroids may downregulate the number of dendritic.

Administration, Inhalation↗
PubMed1995

Genetic susceptibility to asthma--bronchial hyperresponsiveness coinherited with a major gene for atopy.

BACKGROUND: Bronchial hyperresponsiveness, a risk factor for asthma, consists of a heightened bronchoconstrictor response to a variety of stimuli. The condition has a heritable component and is closely related to serum IgE levels and airway inflammation. The basis for these relations is unknown, as is the mechanism of genetic susceptibility to bronchial hyperresponsiveness. We attempted to define the interrelation between atopy and bronchial hyperresponsiveness and to investigate the chromosomal location of this component of asthma. METHODS: We studied 303 children and grandchildren of 84 probands with asthma selected from a homogeneous population in the Netherlands. Ventilatory function, bronchial responsiveness to histamine, and serum total IgE were measured. The association between the last two variables was evaluated. Using analyses involving pairs of siblings, we tested for linkage between bronchial hyperresponsiveness and genetic markers on chromosome 5q31-q33, previously shown to be linked to a genetic locus regulating serum total IgE levels. RESULTS: Serum total IgE levels were strongly correlated (r = 0.65, P < 0.01) in pairs of siblings concordant for bronchial hyperresponsiveness (defined as a > or = 20 percent decrease in the forced expiratory volume in one second produced by histamine [threshold dose, < or = 16 mg per milliliter]), suggesting that these traits are coinherited. However, bronchial hyperresponsiveness was not correlated with serum IgE levels (r = 0.04, P > 0.10). Analyses of pairs of siblings showed linkage of bronchial hyperresponsiveness with several genetic markers on chromosome 5q, including D5S436 (P < 0.001 for a histamine threshold value of < or = 16 mg per milliliter). CONCLUSIONS: This study demonstrates that a trait for an elevated level of serum total IgE is coinherited with a trait for bronchial hyperresponsiveness and that a gene governing bronchial hyperresponsiveness is located near a major locus that regulates serum IgE levels on chromosome 5q. These findings are consistent with the existence of one or more genes on chromosome 5q31-q33 causing susceptibility to asthma.

Adolescent↗
PubMed1995

Persistence and new onset of asthma and chronic bronchitis evaluated longitudinally in a community population sample of adults.

BACKGROUND: Some patients with chronic obstructive pulmonary disease may share the clinical characteristics of those with asthma; their disease is sometimes called "asthmatic bronchitis." Whether there is a difference between asthmatics who do and do not develop chronic bronchitis is not yet clear. We investigated whether asthma and chronic bronchitis may share some "allergic" phenotypes and whether asthmatic individuals who develop chronic bronchitis subsequently have steeper declines in lung function. METHODS: Known risk factors for decline in lung function were analyzed in a representative community population of adults followed up longitudinally since 1972 in Tucson, Ariz, in groups with persistent, newly developed, and past diagnoses of asthma and chronic bronchitis. We evaluated contributions of initial level of forced expiratory volume in 1 second (FEV1), reversibility with isoproterenol hydrochloride nebulized aerosol bronchodilator treatment, percentage of blood eosinophils to determine eosinophilia, and IgE level. RESULTS: The concurrence of chronic bronchitis and asthma is associated with a steeper decline in FEV1 than is asthma as the sole diagnosis. Asthmatics (those with persistent asthma with and without chronic bronchitis) had the greatest prevalence of increased reversibility with isoproterenol therapy and with eosinophilia. The prevalence of eosinophilia was also high in those with newly diagnosed chronic bronchitis without asthma; however, this was not the case in those with persistent chronic bronchitis without asthma. Larger bronchodilator responses were related to steeper declines in FEV1, both in persistent asthma and in chronic bronchitis. CONCLUSIONS: Bronchodilator response and eosinophilia are generally believed to be hallmarks of asthma. We show that these characteristics may be present in chronic bronchitis as well. The presence of a large (> 25%) bronchodilator response is associated with a steeper decline in FEV1.

Adult↗
PubMed1995

Inflammatory cell number and mediators in bronchoalveolar lavage fluid and peripheral blood in subjects with asthma with increased nocturnal airways narrowing.

BACKGROUND: Increased nocturnal airways narrowing (NAN) in asthma is thought to occur as the result of intensification of inflammatory processes in the airways. In this study we investigated the presence of inflammatory cells and mediators in bronchoalveolar lavage (BAL) fluid and peripheral blood (PB) and assessed their relationship with the occurrence of increased NAN. METHODS: BAL fluid and PB samples were assessed at 16:00 and 04:00 hours, separated by 7 days or more, in eight nonatopic healthy subjects (group 1) and 17 atopic subjects with asthma who were using inhaled bronchodilators only. The latter subjects were prospectively assigned to groups with and without NAN, as defined by a mean circadian peak expiratory flow variation of less than 15% (group 2) and 15% or more (group 3), respectively. RESULTS: Significantly higher eosinophil numbers and inflammatory activation products (eosinophil cationic protein, eosinophil-derived neurotoxin, histamine) were found in BAL fluid and PB from subjects with asthma in comparison with control subjects. However, increased NAN was not generally associated with a circadian fluctuation in cell number and inflammatory mediators in BAL fluid and PB. No differences in inflammatory cell numbers existed that distinguished between groups 2 and 3. However, in group 3 significantly higher BAL prostaglandin D2 levels (70 vs 24 pg/ml; range, 28 to 102 vs 11 to 90 pg/ml; p = 0.04) and serum eosinophil cationic protein levels (17.6 vs 16.1 ng/ml; range, 6.3 to 17.5 vs 6.3 to 60.3 ng/ml; p = 0.03) at 16:00 hours were detected compared with group 2. CONCLUSIONS: Our findings suggest that increased NAN is more likely to occur in subjects with asthma with ongoing increased cellular activation during the day.

Adolescent↗