F. W. S. Ko

Effects of air pollution on asthma hospitalization rates in different age groups in Hong Kong

Aims To assess the relationship between levels of ambient air pollutants and hospitalization rates for asthma in Hong Kong (HK).

Validation of a portable recording device (ApneaLink) for identifying patients with suspected obstructive sleep apnoea syndrome

Background: Polysomnography (PSG) is currently the standard diagnostic procedure for sleep apnoea. This study evaluates the diagnostic accuracy of a portable recording device, ApneaLink (AL; ResMed, Poway, CA, USA) for detection of sleep apnoea in comparisons against PSG.

Declining asthma prevalence in Hong Kong Chinese schoolchildren

Background Many studies have reported an increase in the prevalence of asthma and related atopic disorders. The lack of standardized methodologies and ‘objective’ measurements make reliable comparison and monitoring of trends of asthma very difficult.

High levels and gender difference of exhaled nitric oxide in Chinese schoolchildren

Background Exhaled nitric oxide (eNO) may represent a useful noninvasive marker of airway inflammation, but data on the reference population values in schoolchildren are limited. No reference eNO study in Asian children has been published.

Polymorphisms in manganese superoxide dismutase and catalase genes: functional study in Hong Kong Chinese asthma patients

BACKGROUND Reactive oxygen species may contribute to the pathogenesis of asthma. Functional genetic polymorphisms of antioxidant enzymes, superoxide dismutase (SOD) and catalase are good candidates for asthma susceptibility. OBJECTIVE To investigate the association of the manganese-containing form of SOD (MnSOD) gene at amino acid position 16 (Val16Ala) and catalase gene in the promoter at A-21T and C-262T polymorphisms and asthma in a Hong Kong Chinese population. METHODS The association study was conducted in a case-control design in asthma patients (n=251) and healthy controls (n=316) by genotyping. The functional significance was assessed by determining erythrocyte SOD and catalase activity. RESULTS The Val allele of MnSOD at Val16Ala and the A allele of catalase gene at A-21T were not different between patients and controls, while the C allele of catalase gene at C-262T was found to be significantly different between patients and controls (P=0.033). The less frequent variant of catalase gene (-262T) was found to be protective from the development of asthma in a Hong Kong Chinese non-smoking population (adjusted odds ratio=0.35, 0.15-0.85; P=0.017). Asthma patients had elevated erythrocyte SOD and catalase activities in comparison with healthy controls (P<0.01). However, their activities were not associated with different genotypes within healthy controls or asthma patients. CONCLUSION This is the first report showing that SOD and catalase functional activities are not associated with their respective genetic polymorphisms but related to the presence of asthma in a Hong Kong Chinese population.

Increased macrophage-derived chemokine in exhaled breath condensate and plasma from children with asthma

Background Type 2 helper T lymphocyte‐specific chemokines including macrophage‐derived chemokine (MDC), thymus and activation‐regulated chemokine (TARC) and eotaxin are important mediators for allergic airway inflammation.

Prevalence of snoring and sleep-disordered breathing in a group of commercial bus drivers in Hong Kong

Objectives: To assess the prevalence of sleep‐disordered breathing (SDB) and its associated symptoms in a group of commercial bus drivers in Hong Kong.

Increased expression of plasma and cell surface co‐stimulatory molecules CTLA‐4, CD28 and CD86 in adult patients with allergic asthma

The co‐stimulatory interactions of the B7 family molecules CD80 and CD86 on antigen‐presenting cells, together with their T cell counter receptors CD28 and cytotoxic T lymphocyte‐associated antigen‐4 (CTLA‐4), modulate T lymphocyte‐mediated immune responses in a reciprocal manner. To investigate whether there is altered expression and the clinical significance of soluble co‐stimulatory molecules in asthmatic patients, plasma concentrations of sCTLA‐4, sCD28, sCD80 and sCD86 in 51 adult allergic asthmatic adults with or without steroid treatment, and 35 sex‐ and age‐matched control subjects were measured by enzyme‐linked immunosorbent assay (ELISA). Cell surface expression of CTLA‐4 and CD28 on peripheral blood mononuclear cells (PBMC) were analysed by flow cytometry. Results showed that the plasma sCTLA‐4 concentration was significantly higher in all asthmatic patients while sCD28 and sCD86 concentrations were significantly higher in steroid and non‐steroid treated asthmatic patients, respectively, compared with control subjects (all P < 0·01). Significantly increased cell surface expression of CD28 but not CTLA‐4 on PBMC was found in asthmatic patients compared with controls (P < 0·05). The plasma concentration and cell surface expression of CTLA‐4 were found to exhibit positive and significant correlations with those of CD28 (both P < 0·05). Serum total IgE concentration correlated positively and significantly with sCTLA‐4 and sCD28 concentrations in allergic asthmatic patients (both P < 0·05). The increased expression of these soluble co‐stimulatory molecules may reflect the dysregulation of T cell activation, thereby contributing to the immunopathogenesis of allergic asthma.

Nitric oxide synthase polymorphisms and asthma phenotypes in Chinese children.

Background Nitric oxide (NO) is a key factor for balancing T‐helper type 1/T‐helper type 2 immunity. Single nucleotide polymorphisms (SNPs) in nitric oxide synthase (NOS) genes have been associated with atopy and exhaled NO concentrations in Caucasians. We investigated the association between asthma traits and genetic polymorphisms in neuronal NO synthase (NOS1) and endothelial NO synthase (NOS3) in Chinese children.

Prevalence and risk factors of airflow obstruction in an elderly Chinese population

It is common practice to use a forced expiratory volume in one second (FEV1)/ forced vital capacity (FVC) ratio of <70% as evidence of airflow obstruction. As the FEV1/FVC ratio falls with age, the lower limit of normal range (LLN), defined as the bottom 5% in a health reference population, of FEV1/FVC ratio has been suggested as a better index to reduce over-diagnosis of chronic obstructive pulmonary disease (COPD), particularly in the elderly. However, there are no large scale studies that focus on the diagnosis of COPD in the elderly based on these definitions. The present prospective epidemiological study involved 1,149 elderly subjects aged ≥60 yrs in the community. Detailed questionnaires, pre- and post-bronchodilator spirometry were performed. In total, 1,008 subjects (mean age 74.2±6.4 yrs; 271 males) completed satisfactory spirometry testing. Airflow obstruction was present in 25.9% as defined by the post-bronchodilator FEV1/FVC ratio of <70% and in 12.4% defined by the LLN of FEV1/FVC ratio. Moderate COPD, at least, was found in 14.0% of patients according to the post-bronchodilator FEV1/FVC ratio of <70% and in 8.5% of patients according to LLN of FEV1/FVC ratio. In the present elderly Chinese population (mostly females, with low education level and previous exposure to biomass during formative years), the prevalence of chronic obstructive pulmonary disease varied markedly depending on definitions adopted. Further longitudinal studies are needed to determine the precise definition of chronic obstructive pulmonary disease.