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Background: Exposure to allergens or air pollutants often leads to asthma exacerbations associated with aggravation of airway inflammation. Although, repeated allergen challenge often induces chronic allergic airway inflammation (CAAI) and airway remodelling, yet, the effects of brief exposure to air pollutants such as SO(2) on development of CAAI and airway remodelling remain to be clarified., Objective: The aim of the experiment was to investigate the effects of acute neutrophilic airway inflammation induced by brief exposure to SO(2) on development of CAAI and subepithelial fibrosis (SEF) in a murine model of asthma., Methods: Acute airway inflammation was induced by brief exposure to 50 p.p.m. SO(2) (1 h/d, 3 days). CAAI and SEF in BALB/c mice were induced by repeated challenge with ovalbumin (OVA) for 5 or 9 weeks with or without prior exposure to SO(2). Bronchoalveolar lavage fluid (BALF) eosinophilia as index of CAAI, BALF endothelin-1 (ET-1) and TGF-beta1 levels, morphometric evaluation of fibrotic area beneath subbasement membrane and lung hydroxyproline content (Hyp) as indexes of SEF were monitored., Results: Exposure to SO(2) led to acute neutrophilic inflammation and epithelial sloughing with profound elevation of BALF ET-1. Repeated OVA challenge resulted in CAAI and SEF along with elevation of Hyp, increase of fibrotic area beneath subbasement membrane and elevation of BALF TGF-beta1. Preceding SO(2) exposure exaggerated BALF eosinophilia, facilitated and enhanced SEF with more significant elevation of BALF ET-1 and TGF-beta1 levels compared with OVA-challenged mice without prior exposure to SO(2). The increase of Hyp was positively correlated with elevation of BALF TGF-beta1 during CAAI (r=0.842, P<0.01)., Conclusion: This data demonstrated that SEF developed in parallel with severity and time course of CAAI following repeated OVA challenge. SO(2)-induced acute epithelial injury and neutrophilic inflammation could enhance CAAI and promote SEF, probably through overexpression of ET-1 and TGF-beta1.

Background: Asthma is a common chronic disease and information on its management practices at the community level is helpful in identifying problems and improving asthma care., Objective: To assess the severity status and management of the asthma symptom of wheeze of children at the community level in Hong Kong (HK) and Guangzhou (GZ)., Methods: Cross-sectional study of children aged 10 years using the International Study of Asthma and Allergic disease in Childhood (ISAAC Phase II protocol). Asthma management and lung function were assessed in 178 (98 from HK and 80 from GZ) randomly selected children with wheeze over the past 12 months., Results: Eighty-three percent, 11%, 6% and 0% of children suffered from intermittent, mild persistent, moderate persistent and severe persistent asthma, respectively, according to the frequency of their symptoms. Addition of spirometric parameter only changed the asthma severity classification in 2.8% of children. Medications were used by 30.6% and 71.3% of children for wheeze in HK and GZ, respectively. In HK, inhaled beta(2)-agonist (73.3% among the drug users) was the commonest medication used followed by inhaled corticosteroid (ICS) (23.3%). In GZ, inhaled beta(2)-agonist was used by 75.4% of children, but use of ICS (26.3%), oral beta(2)-agonist (26.3%), oral theophylline (45.6%), oral ketotifen (36.8%) and oral steroid (35.1%) were also common. ICS was only used by 11.4% of children with persistent asthma. Ten percent and 18.7% of children in HK and GZ, respectively, had emergency department visits, while 16.3% and 11.6% of children in HK and GZ, respectively, had missed school secondary to asthma over the past 1 year., Conclusions: Most children in the community had intermittent asthma and addition of lung function to symptoms did not significantly affect classification of asthma severity. Significant morbidity was seen even in this group of children with mostly intermittent and mild persistent asthma.

Background: Epidemiological surveys have shown that the prevalence of asthma in the Asian population is relatively low. Within the Chinese population, schoolchildren from Hong Kong were found to have the highest rate of asthma., Objective: To compare the prevalence of respiratory and atopic disorders, and to assess the role of atopy in the development of asthma, in Chinese schoolchildren from Hong Kong, Beijing and Guangzhou., Methods: Community-based random samples of schoolchildren aged 9-11 years from three Chinese cities (Hong Kong, Beijing and Guangzhou) were recruited for study using the International Study of Asthma and Allergies in Childhood (ISAAC) Phase II protocol. Subjects were studied by parental questionnaires (n = 10902), skin-prick tests (n = 3479) and skin examination (n = 3479)., Results: The prevalence rates of current wheeze, speech limiting wheeze, rhinoconjunctivitis and flexural dermatitis were significantly more common in Hong Kong than in Beijing or Guangzhou. The atopy rate was also higher in Hong Kong (41.2%) than in Beijing (23.9%) or Guangzhou (30.8%). Atopy was strongly correlated with current wheeze (OR 7.74; 95% CI = 5.70-10.51). Subgroup analyses of children from Hong Kong revealed that children born in mainland China who had subsequently migrated to Hong Kong had a significantly lower rate of allergic symptoms and atopy than those children born in Hong Kong., Conclusion: Using a standardized written questionnaire along with a skin prick test and skin examination, we confirmed that the prevalence of asthma, allergic diseases and atopy was highest in schoolchildren from Hong Kong. Atopic sensitization is an important factor associated with asthma in Chinese children.

Background: There is evidence that tumour necrosis factor alpha (TNF alpha) may be an important mediator in initiating asthmatic airway inflammation. It has been proposed that endothelin-1 (ET-1) is involved in bronchoconstriction and airway remodelling in asthma. It is not known, however, if there is any interaction between TNF alpha and ET in perpetuating airway inflammation in asthma., Objective: The present study aimed to determine the activities of ET-1 and TNF alpha in ovalbumin-sensitized guinea pigs and their roles in the development of airway inflammation., Method: Twelve guinea pigs were sensitized by ovalbumin injection and aerosol inhalation. ET-1 levels were measured in both bronchoalveolar lavage fluid (BALF) and plasma by 125-labelled endothelin-1 (ET-1) radioimmunoassay. The TNF alpha activity released from alveolar macrophage (AM) in BALF was estimated by ELISA. Cultured bovine airway smooth muscle cells (BASMCs) were treated with TNF alpha (1000 units/5 x 10(4) cells) for different times. ET-1 levels in harvested medium from these cells were measured by radioimmunoassay. Cultured human fetal lung fibroblasts (HFLFs) were incubated with ET-1 (10(-8) approximately 10(-6)M), then 3HTdR incorporation to these cells and cell counting were performed. The effects of ET-1 stimulation on the granulocyte macrophage colony stimulating factor (GM-CSF) gene expression in HFLFs were estimated by using RT-PCR method., Results: ET-1 levels in both plasma and BALF were significantly higher in ovalbumin-sensitized guinea-pigs compared with those in controls (422.27 +/- 175.0 pg/mL vs 277.311 +/- 88.0 pg/mL, P < 0.05, 81.22 +/- 16.15 vs 49.81 +/- 12.64 pg/mL, P < 0.05) while TNF alpha activity was also significantly increased in the OVA-sensitized group compared with that in the control group (6010 +/- 1900 pg/mL vs 2810 +/- 450 pg/mL, P < 0.05). The ET-1 level in harvested medium of BASMCs rose significantly in 12 h in the TNF-alpha treated group (from < 5 pg/mL to 53.72 +/- 14.3 pg/mL, P < 0.001), and remained at a similar level for 24 h in the TNF alpha treated group. It was shown that ET-1 not only stimulated cell proliferation but also induced GM-CSF mRNA expression in HFLFs., Conclusion: ET-1 levels in both plasma and BALF and TNF alpha release from macrophage are increased significantly in ovalbumin-sensitized guinea-pigs. TNF alpha stimulates ET-1 secretion from cultured BASMCsw; ET-1 accelerates cell proliferation and induces GM-CSF mRNA expression in the human fetal lung fibroblast.

Sputum samples from patients with chronic bronchitis were assayed for histamine content using a bioassay, and/or fluorometric assay and single or double radioenzymatic techniques. Comparison showed that all the assays produced significant differences in the measurement of sputum histamine. Similarly, it was observed that the assays all showed significant differences in the measurement of histamine released from human basophils. In general the fluorometric assay give the highest values for histamine in sputum and the double-isotope radioenzymatic assay the lowest. In contrast, no differences were found between the bioassay, fluorometric assay and the single-isotope radioenzymatic assay for the measurement of histamine added to Tyrode's solution. These results suggest that in biological samples some of the assays may additionally be measuring metabolites of histamine or other components present in the samples and underline the need to measure the levels of histamine and its metabolites separately in sputum.