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Moira Chan-Yeung

Publications and source records attributed to Moira Chan-Yeung.

At least 19 recordsLinked to original sources
PubMed2006

Primary prevention of childhood asthma and allergic disorders.

PURPOSE OF REVIEW: The prevalence of asthma and allergic disorders in childhood is increasing in many parts of the world. This review focuses on recent findings with regard to environmental risk factors and their manipulation in the primary prevention of these diseases in childhood. RECENT FINDINGS: Recent studies have failed to resolve the controversy on the subject of exposure to indoor aeroallergens and the risk of sensitization and asthma in childhood. Bronchiolitis due to respiratory syncytial virus in infancy is associated with a significant increase in risk of asthma, but not atopy. In the prevention of these diseases, the effects of breastfeeding are controversial, with studies showing a protective effect in children without allergic predisposition, but other studies showing no effect or even the potential for an increased asthma risk. A significant reduction in the prevalence of doctor-diagnosed asthma at 7 years was found in a randomized controlled multifaceted (reduction of inhaled and ingested allergens) intervention study of high-risk infants. Other intervention measures, such as an education program on how to reduce exposure, the use of probiotics, and immunization against infections, all showed some protective effects. SUMMARY: More research is required, especially with regard to longer periods of follow-up for all current intervention studies aimed at reducing exposure, the onset and duration of intervention, and other novel intervention measures in the primary prevention of asthma and allergic diseases in childhood.

Animals↗
PubMed2006

Longitudinal profile of antibodies against SARS-coronavirus in SARS patients and their clinical significance.

BACKGROUND: Severe acute respiratory syndrome (SARS) is a newly discovered disease caused by a novel coronavirus. The present study studied the longitudinal profile of antibodies against SARS-coronavirus (SARS-CoV) in SARS patients and evaluated the clinical significance of these antibodies. METHODS: Two methods, ELISA and indirect immunofluorescent assay, were used for the detection of the anti-SARS-CoV IgG and IgM in 335 serial sera from 98 SARS patients. In 18 patients, serum antibody profiles were investigated and antibody neutralization tests were performed from 7 to 720 days after the onset of symptoms. RESULTS: The ratios of positive IgG/IgM by ELISA were 0/0, 45.4/39.4, 88.6/71.4, 96/88, 100/48.6, 100/30.9, 100/17.1, 100/0 per cent, respectively, on 1-7, 8-14, 15-21, 22-28, 29-60, 61-90, 91-180 and 181-720 days after the onset of symptoms. Antibodies were not detected within the first 7 days of illness, but IgG titre increased dramatically on day 15, reaching a peak on day 60, and remained high until day 180 from when it declined gradually until day 720. IgM was detected on day 15 and rapidly reached a peak, then declined gradually until it was undetectable on day 180. Neutralizing viral antibodies were demonstrated in the convalescence sera from SARS patients. CONCLUSION: The persistence of detectable IgG antibodies and neutralizing viral antibodies for up to 720 days suggest that SARS patients may be protected from recurrent SARS-CoV infection for up to 2 years.

Adult↗
PubMed2006

Population-based prospective molecular and conventional epidemiological study of tuberculosis in Hong Kong.

OBJECTIVE: To study the transmission of tuberculosis using conventional and molecular epidemiology in Hong Kong. METHODS: All patients with positive sputum culture for Mycobacterium tuberculosis residing on the Island of Hong Kong were recruited from May 1999 to April 2002. The restriction fragment length polymorphism technique was used to determine DNA patterns of isolates of M. tuberculosis using the IS6110 probe, supplemented by pTBN12 as a secondary probe. RESULTS: One thousand five hundred and fifty-three of 2337 (66%) of the patients with bacteriologically confirmed tuberculosis had restriction fragment length polymorphism analysis of their M. tuberculosis isolates. Four hundred and fifty-four (29.2%) patients belonging to 143 clusters were identified; the estimated rate of recent transmission was 20-24%. Significant predictors of clustering included young-age groups (<40 years) versus those >60 years of age (adjusted odds ratio (OR) 1.96, 95% confidence interval 1.47-2.62), permanent residency versus new or non-residents (adjusted OR 3.40, 95% 1.84-6.26) and previous default from treatment versus new cases (adjusted OR 6.12, 95% confidence interval 1.82-20.5). Alcohol and drug abuse, history of imprisonment and HIV infection were not significant risk factors for molecular clustering. Of patients belonging to clusters, 5.1% had definite, 5.5% had probable and 24.4% had possible epidemiological link, suggesting casual contact may be responsible for a high proportion of the clustered cases. CONCLUSION: One-fifth to one quarter of the new cases of active tuberculosis in Hong Kong are due to recent transmission. In addition to early diagnosis and successful treatment of all active disease, treatment of latent disease should receive more attention in the control of tuberculosis in Hong Kong.

Age Distribution↗
PubMed2006

Prevalence of tuberculous infection and active tuberculosis in old age homes in Hong Kong.

OBJECTIVES: To assess the prevalence of tuberculous infection and active tuberculosis (TB) in old age homes in Hong Kong and to determine whether there is institutional transmission in these homes. DESIGN: Cross-sectional. SETTING: Old age homes. PARTICIPANTS: Total of 2,243 residents, representing 84.6% of all residents in 15 old age homes; 1,698 were women, and 545 were men, with an average age of 82. MEASUREMENTS: All residents had a questionnaire-based interview, medical record review, two-stage tuberculin testing using two units purified protein derivative-RT23, and a chest x-ray. Those with radiological abnormalities had sputum examined for acid-fast bacilli. RESULTS: The estimated prevalence rate of active TB in this population was 669 per 100,000, significantly higher in men than in women (1,101 per 100,000 vs 530 per 100,000). The proportion with positive tuberculin reactivity (> or =10 mm induration) after two-stage testing was 68.6%, significantly higher in men than in women. There was no evidence of active transmission of disease in these old age homes, with restriction fragment length polymorphism (RFLP) analysis performed on five cases of active pulmonary TB in the home with the highest rate of TB showing unique RFLP patterns. CONCLUSION: The rate of active TB and TB infection in old age homes in Hong Kong is still high. Because treatment for latent TB carries a high risk for liver dysfunction in this population, clinicians and other healthcare workers need a high index of suspicion and to diagnose and treat this disease as early as possible to prevent transmission.

Aged↗
PubMed2005

Evaluation by indirect immunofluorescent assay and enzyme linked immunosorbent assay of the dynamic changes of serum antibody responses against severe acute respiratory syndrome coronavirus.

BACKGROUND: Severe acute respiratory syndrome coronavirus (SARS-CoV) is a newly emerging virus that gives rise to SARS patients with high rates of infectivity and fatality. To study the humoral immune responses to SARS-CoV, the authors evaluated IgG and IgM specific antibodies in patients' sera. METHODS: Two methods, enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescent assay (IFA), were used to detect specific serum IgG and IgM against SARS-CoV in 98 SARS patients and 250 controls consisting of patients with pneumonia, health-care professionals and healthy subjects. The serum antibody profiles were investigated at different times over one and a half years in 18 of the SARS patients. RESULTS: The sensitivity and specificity of ELISA for detecting IgG against SARS-CoV were 100.0% and 97.2% and for IgM 89.8% and 97.6% respectively; the figures using IFA for IgG were 100.0% and 100.0% and for IgM 81.8% and 100.0% respectively. During the first seven days of the antibodies trace test, no IgG and IgM were detected, but on day 15, IgG response increased dramatically, reaching a peak on day 60, remaining high up to day 180 and decreasing gradually until day 540. On day 15, IgM was detected, rapidly reached a peak, then declined gradually until day 180 when IgM was undetectable. CONCLUSION: The detection of antibodies against SARS virus is helpful in the clinical diagnosis of SARS.

Adult↗
PubMed2005

The Canadian Childhood Asthma Primary Prevention Study: outcomes at 7 years of age.

BACKGROUND: Avoidance of any one of the individual risk factors associated with childhood asthma has not been successful in preventing its development. OBJECTIVE: The purpose of this study is to determine the effectiveness of a multifaceted intervention program for the primary prevention of asthma in high-risk infants at 7 years of age. METHODS: Five hundred forty-five high-risk infants with an immediate family history of asthma and allergies were prospectively randomized into intervention or control groups prenatally. Intervention measures introduced before birth and during the first year of life included avoidance of house dust, pets, and environmental tobacco smoke and encouragement of breast-feeding with delayed introduction of solid foods. Assessment of outcomes at 7 years consisted of examination by pediatric allergists, methacholine inhalation tests, and allergy skin tests. RESULTS: At 7 years, 469 of the 545 children were contacted, and 380 returned for further assessment. The prevalence of pediatric allergist-diagnosed asthma was significantly lower in the intervention group than in the control group (14.9% vs 23.0%; adjusted risk ratio, 0.44; 95% CI, 0.25-0.79). The prevalence of allergic rhinitis, atopic dermatitis, atopy (defined as positive skin test reactions to any common allergen), and bronchial hyperresponsiveness (defined as the provocative concentration of methacholine that induced a 20% decrease in FEV 1 from a postsaline value of less than 7.8 mg/mL) were not significantly different between the 2 groups. The prevalence of asthma (defined as wheeze without colds and the presence of bronchial hyperresponsiveness) was also significantly lower in the intervention group compared with the control group (12.9% vs 25.0%; adjusted risk ratio, 0.39; 95% CI, 0.22-0.71). CONCLUSION: The multifaceted intervention program was effective in reducing the prevalence of asthma in high-risk children at 7 years of age.

Asthma↗
PubMed2005

Antioxidant enzyme activities in healthy Chinese adults: influence of age, gender and smoking.

OBJECTIVE: Specific antioxidant enzymes play a vital role in regulating and maintaining oxidant species. The aim of this study was to determine these antioxidant enzyme activities (i.e. catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)) in erythrocytes from a group of healthy Chinese subjects and to study the influence of age, gender and smoking habits on the enzyme activities. METHODOLOGY: Chinese healthy subjects (n = 276) were grouped according to their age range, gender differences and smoking habits. Antioxidant enzyme activities were measured spectrophotometrically using standard kinetic methods. RESULTS: There was a significant decrease in erythrocyte GPx activity in ever-smokers compared with non-smokers (47.10 +/- 1.33 mU/g haemoglobin (Hb) vs. 51.41 +/- 1.64 mU/g Hb, P < 0.05). Age-related significant increases in erythrocyte CAT and SOD activities were found in non-smokers but not in ever-smokers. There was no age-related difference in erythrocyte GPx activity in either non-smokers or ever-smokers. Among those >60 years old, erythrocyte CAT and GPx activities were significantly lower in ever-smokers than in non-smokers (29.70 +/- 3.07 mU/g Hb vs. 41.63 +/- 4.92 mU/g Hb (P < 0.05), and 47.55 +/- 2.00 mU/g Hb vs. 55.30 +/- 3.60 mU/g Hb (P < 0.05), respectively). It was also found that females had higher erythrocyte GPx activity than males but this difference did not reach significance in non-smokers. CONCLUSION: From the results of this study, it is concluded that oxidative stress seems to be present in elderly ever-smokers among the Chinese population.

Adolescent↗
PubMed2005

Impact of smoking policy on the respiratory health of food and beverage servers.

OBJECTIVES: The purpose of this study was to determine whether workplace smoking policy was associated with respiratory health effects among food and beverage servers. METHODS: Data were obtained from a postal survey of hospitality workers. The participation rate for the questionnaire was 73.9% of those contacted. Current smokers were excluded from the analysis. Adjustment for differences between groups in age, gender, ex-smoker versus never smoker status, home exposure environmental tobacco smoke, childhood asthma, mail versus telephone questionnaire, and hours worked per week was done using logistic regression. A subset of 88 nonsmokers underwent laboratory evaluation, including spirometry and hair nicotine analysis. RESULTS: The prevalence of irritant and respiratory symptoms among 383 nonsmokers was consistently higher among the participants from premises where smoking was permitted without restrictions on the workplace. In comparison with those from facilities where smoking was prohibited, the highest adjusted odds ratios (OR) were for chronic phlegm for those working where smoking was permitted (OR 8.5 95% confidence interval (95% CI) 2.4-30.0] or where there were partial smoking restrictions (OR 5.7 95% CI 1.7-19.4). Lung function was not reduced apart from the ratio between forced expiratory volume in 1 second and forced vital capacity, which was lower for workers from facilities where smoking was permitted. Hair nicotine levels were lowest for workers from facilities where smoking was prohibited. CONCLUSIONS: The results suggest that occupational exposure to environmental tobacco smoke, determined through smoking policies, can adversely affect the respiratory health of nonsmokers who work in the food and beverage service industry.

Adult↗
PubMed2004

The Canadian asthma primary prevention study: outcomes at 2 years of age.

BACKGROUND: Avoidance of individual risk factors have not been successful in preventing the development of asthma. OBJECTIVE: We sought to determine the effectiveness of a multifaceted intervention program in primary prevention of asthma in high-risk infants. METHODS: We identified 545 high-risk infants on the basis of an immediate family history of asthma. Families were randomized into intervention or control groups. Intervention measures included avoidance of house dust mite, pet allergen, and environmental tobacco smoke. Breast-feeding was encouraged with formula supplementation if necessary, and introduction of solid foods was delayed. RESULTS: At 2 years of age, 19.5% of the children had asthma, and 14.7% had atopy (positive skin test response to one or more common allergens). Significantly fewer children had asthma in the intervention group compared with in the control group (16.3% vs 23.0%), with 60% less persistent asthma at 2 years. There was a 90% reduction for recurrent wheeze in the intervention group compared with that seen in the control group. Exposure to maternal environmental tobacco smoke during pregnancy or the first year was a risk factor for asthma at 2 years of age. A positive skin test response, particularly to food, at 12 months predicted asthma at 2 years. There was no significant difference for atopy between the intervention and control groups, but daycare reduced atopy at 2 years. CONCLUSION: This multifaceted intervention program during a window of opportunity in the first year of life was effective in preventing asthma in high-risk children at 2 years of age. Future studies with this cohort at school age are important.

Allergens↗
PubMed2004

Systemic oxidative and antioxidative status in Chinese patients with asthma.

BACKGROUND: Patients with asthma generate an increased amount of reactive oxygen species from peripheral blood cells. Reactive oxygen species produce many of the pathophysiologic changes associated with asthma and may contribute to its pathogenesis. OBJECTIVE: We investigated changes in antioxidant enzyme activities and oxidized glutathione (glutathione disulfide; GSSG) levels in erythrocytes from a group of healthy control Chinese subjects (n=135) and patients with asthma (n=106). METHODS: Baseline pulmonary function was measured for all subjects. Antioxidant status was evaluated by measuring erythrocyte superoxide dismutase, catalase, and glutathione peroxidase activities. Oxidative stress was also measured in terms of GSSG in erythrocytes with a kinetic microassay. RESULTS: Patients with asthma had significantly increased erythrocyte superoxide dismutase and catalase activities compared with controls (61.10 +/- 1.30 U/g hemoglobin [Hb] vs 55.51 +/- 1.82 U/g Hb [P=.018] and 0.0637 +/- 0.0021 U/g Hb vs 0.0257 +/- 0.0120 U/g Hb [P <.001] for the asthma and control groups, respectively). Conversely, erythrocyte glutathione peroxidase activity decreased (44.21 +/- 1.33 mU/g Hb vs 50.07 +/- 1.39 mU/g Hb for the asthma and control groups, respectively; P=.003). Patients with asthma also had significantly higher GSSG levels in erythrocyte hemolysates compared with controls (167.40 +/- 2.93 micromol/L vs 44.98 +/- 0.44 micromol/L for the asthma and control groups, respectively; P <.001), indicating increased oxidative stress. CONCLUSIONS: Asthma is accompanied by an alteration in systemic antioxidant status due to possible oxidative stress in this disease.

Adult↗
PubMed2004

Lung cancer susceptibility and polymorphisms of glutathione-S-transferase genes in Hong Kong.

OBJECTIVE: To study the potential role of genetic polymorphisms of glutathione-S-transferases GSTM1, GSTT1 and GSTP1 in susceptibility to lung cancer in Hong Kong Chinese. METHODS: 229 consecutive incident patients with a histological diagnosis of lung cancer from a regional hospital and 197 healthy population-based controls were recruited for this study between July 1999 and June 2001. Genetic polymorphisms of GSTT1 and GSTM1 were determined using PCR-based technique. RESULTS: The frequencies of GSTT1 and GSTM1 null genotypes were 51.8 and 59.4% in healthy controls and 63 and 54.7%, respectively, in lung cancer patients. GSTP1 Val105/Val105 genotype was found in only 1% of healthy controls. The risk for lung cancer with GSTT1 null genotype was significantly higher, adjusted odds ratio (OR) 1.69, 95% confidence interval (CI) 1.12-2.56, compared with those with the GSTT1 genotype; the increase in risk was found only in non-smokers. GSTM1 null genotype, combined GSTT1 and GSTM1 null genotype and GSTP1 Val105/Val105 genotype did not confer any increase risk for lung cancer. CONCLUSION: GSTT1 null genotype is associated with an increased risk for lung cancer in non-smoking Chinese in Hong Kong.

Adult↗
PubMed2004

Geographic and gender variability in the prevalence of bronchial responsiveness in Canada.

OBJECTIVES: Geographic variability in reported prevalences of asthma worldwide could in part relate to interpretation of symptoms and diagnostic biases. Bronchial responsiveness measurements provide objective evidence of a common physiologic characteristic of asthma. We measured bronchial responsiveness using the standardized protocol of the European Community Respiratory Health Survey (ECRHS) in six sites in Canada, and compared prevalences across Canada with international sites. DESIGN: Samples of 3,000 to 4,000 adults aged 20 to 44 years were randomly selected in Vancouver, Winnipeg, Hamilton, Montreal, Halifax, and Prince Edward Island, and a mail questionnaire was completed by 18,616 individuals (86.5%). Preselected random subsamples (n = 2,962) attended a research laboratory for examination including more detailed questionnaires, lung function testing including methacholine challenge, and skin testing with 14 allergens. RESULTS: Prevalences of bronchial hyperresponsiveness, measured as cumulative dose of methacholine required to produce a 20% fall from the post-saline solution FEV1 < or = 1 mg, ranged from 4.9% (95% confidence interval [CI], 1.6 to 8.5) in Halifax to 22.0% (95% CI, 18.1 to 26.0) in Hamilton (median, 10.7%). In all Canadian sites, bronchial hyperresponsiveness was more prevalent in women than in men. Neither the geographic nor gender differences were accounted for by differences in age, smoking, skin test reactivity, or baseline FEV1. Geographic- and gender-related variability changed little when only bronchial hyperresponsiveness associated with asthma-like symptoms was considered. CONCLUSIONS: A wide variability in bronchial responsiveness can occur within one country, almost as wide as the range found across all international sites participating in the ECRHS study and not explained by differences in gender, smoking, skin test reactivity, and FEV1. While gender variability in the prevalence of bronchial responsiveness is likely due to hormonal and immunologic factors, geographic variability is likely to result from environmental factors.

Adult↗
PubMed2004

Respiratory health survey of respiratory therapists.

STUDY OBJECTIVES: The purpose of this study was to determine whether respiratory therapists (RTs) had an elevated risk of respiratory symptoms and to determine the association of work exposures with symptoms. METHODS: Mailed questionnaire responses from 275 RTs working in British Columbia, Canada, were compared to those of 628 physiotherapists who had been surveyed previously. Analyses incorporated logistic regression analysis with adjustment for age, sex, smoking status, and childhood asthma. RESULTS: Compared to physiotherapists, RTs had over twice the risk of being woken by dyspnea, having wheeze, asthma attacks, and asthma diagnosed after entering the profession. Among RTs, two work factors associated with asthma were sterilizing instruments with glutaraldehyde-based solutions and the use of aerosolized ribavirin. RTs who used an oxygen tent or hood had the highest risk of asthma diagnosed after entering the profession (odds ratio [OR], 8.3; 95% confidence interval [CI], 12.6 to 26.0) and of asthma attacks in the last 12 months (OR, 3.6; 95% CI, 1.2 to 10.9). CONCLUSIONS: Our data suggest that RTs may be at an increased risk for asthma-like symptoms and for receiving a diagnosis of asthma since starting to work in their profession, possibly related to exposure to glutaraldehyde and aerosolized ribavirin.

Adult↗
PubMed2003

An outbreak of severe acute respiratory syndrome among hospital workers in a community hospital in Hong Kong.

BACKGROUND: During outbreaks, hospital workers are at high risk for nosocomial infection with severe acute respiratory syndrome (SARS)-associated coronavirus. OBJECTIVE: To examine how hospital workers became infected and whether they transmit the virus to their families. DESIGN: Retrospective descriptive study. SETTING: 529-bed community hospital in Hong Kong. PATIENTS: 40 hospital workers infected with SARS-associated coronavirus over a 6-week period (25 March through 5 May 2003). MEASUREMENTS: Percentage of infected hospital workers according to job category. RESULTS: The cumulative incidence was highest among health care assistants, followed by physicians and nurses (8%, 5%, and 4%, respectively). Most hospital workers were infected from direct contact with patients with SARS, who primarily were in general wards and had unsuspected infection. At the time of contact, all hospital workers had used masks but not necessarily other protective devices. Affected hospital workers did not infect their families. CONCLUSION: Before isolation of all patients with clinically confirmed or suspected SARS, routine use of several protective devices, and training of staff in infection control, many health care workers were infected with SARS from patients with unsuspected cases.

Adult↗
PubMed2003

High-dose pulse versus nonpulse corticosteroid regimens in severe acute respiratory syndrome.

The treatment of atypical pneumonia, subsequently termed severe acute respiratory syndrome (SARS), is controversial, and the efficacy of corticosteroid therapy is unknown. We have evaluated the clinical and radiographic outcomes of 72 patients with probable SARS (median age 37 years, 30 M), who received ribavirin and different steroid regimens in two regional hospitals. Chest radiographs were scored according to the percentage of lung field involved. Seventeen patients initially received pulse steroid (PS) (methylprednisolone > or =500 mg/day) and 55 patients initially received nonpulse steroid (NPS) (methylprednisolone <500 mg/day) therapy. The cumulative steroid dosage; intensive care unit admission, mechanical ventilation, and mortality rates; and hematologic and biochemical parameters were similar in both groups after 21 days. However, patients in the PS group had less oxygen requirement, better radiographic outcome, and less likelihood of requiring rescue PS therapy than their counterparts. There was no significant difference between the two groups in hemolytic anemia, severe secondary infections, or hematemesis, but patients in the PS group had less hyperglycaemia. Initial use of pulse methylprednisolone therapy appears to be a more efficacious and an equally safe steroid regimen when compared with regimens with lower dosage and should be considered as the preferred steroid regimen in the treatment of SARS, pending data from future randomized controlled trials.

Adult↗
PubMed2003

Outbreak of severe acute respiratory syndrome in Hong Kong Special Administrative Region: case report.

OBJECTIVE: To describe the outbreak of severe acute respiratory syndrome in Hong Kong. DESIGN: Descriptive case series. SETTING: Hong Kong, Special Administrative Region, China RESULTS: The outbreak started with a visitor from southern China on 21 February. At the hospitals where the first cases were treated the disease spread quickly among healthcare workers, and then out into the community as family members became infected. By 1 April, 685 cases had been reported with 16 deaths. Symptoms include high fever and one or more respiratory symptoms (including cough, shortness of breath, and difficulty breathing). Changes in lung tissue suggest that part of the lung damage is due to cytokines induced by the microbial agent, which has led to empirical treatment with corticosteroids, broad spectrum antiviral agent, and antibacterial cover. There is strong evidence that a novel coronavirus is the pathogen. Precautions for droplet infection should be instituted, including the wearing of masks and rigorous disinfection and hygiene procedures. On 27 March the Department of Health announced drastic measures, including vigorous contact tracing and examination, quarantine of contacts in their homes, and closure of all schools and universities. CONCLUSION: The rapidity of the spread of the disease and the morbidity indicate that the agent responsible is highly infectious and virulent. Strict infection control measures for droplet and contact transmission by healthcare workers, a vigilant healthcare profession, and public education are essential for disease prevention.

Clinical Laboratory Techniques↗