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Biomedical subjects

B W Lee

Publications and source records attributed to B W Lee.

At least 55 records · Page 3Linked to original sources
PubMed2001

Pattern of sensitization to common environmental allergens amongst atopic Singapore children in the first 3 years of life.

This study was aimed to investigate the sensitization pattern to a range of common allergens in young Singaporean children. A cross-sectional study involving 75 children aged below 3 years was carried out. They presented between December 1995 and April 2000 with symptoms of asthma, rhinitis, eczema, or food allergy. Their levels of allergen-specific serum IgE to a panel of foods (egg white, milk, soy protein, shrimp, wheat and peanut), pet dander, dust mites and cockroaches were measured with Pharmacia CAP System radioallergosorbent test kits. Serum IgE levels greater than 0.35 kU/l represented a positive result. Four children could not be tested with the complete panel because of insufficient serum. The prevalence of sensitization was highest for cow's milk (45.9%) followed by egg white (38.7%), dust mites Dermatophagoides pteronyssinus (31.4%) and Blomia tropicalis (25.5%). Sensitization to ingested allergens was significantly more prevalent in children aged 1 year or younger than in the older children (70.4% of those below 1 year, and 50% of those aged 1-3 years; p < 0.02). Sensitization to inhaled allergens, such as dust mites, was more likely to manifest as respiratory symptoms (allergic rhinitis and asthma), while ingested allergens were associated with gastrointestinal symptoms and eczema (p < 0.001). It was concluded that infants and young children are at high risk of sensitization to common environmental substances. Allergen avoidance is therefore important even in the very young. The prevalence of sensitization to food allergens is higher compared to inhalant allergens in young children.

Allergens↗
PubMed2000

Evaluation of the allergenicity of tropical pollen and airborne spores in Singapore.

BACKGROUND: Sensitization to pollen and spores of the Southeast Asian tropical region is not well documented. This study evaluated the allergenicity of the tropical airspora in Singapore. METHODS: On the basis of the results of an aerobiologic survey of the airspora profile of Singapore, crude extracts of 23 main spore (fungal and fern) and pollen types were prepared. A total of 231 patients with asthma and/or allergic rhinitis and 76 healthy controls were evaluated by skin prick test (SPT). Total and specific IgE levels were also quantified by the fluorescence allergosorbent test (FAST). RESULTS: All 23 allergenic extracts tested elicited positive SPT responses. Among the patients with atopic diseases, extracts of oil-palm pollen (Elaeis guineensis) were observed to have the highest frequency of positive reactions (40%), followed by extracts of resam-fern spores (Dicranopteris linearis) (34%) and sea-teak pollen (Podocarpus polystachyus) (33.8%). Fungal spores with the highest SPT responses were Curvularia spp. (26-32%) and Drechslera-like spores (31%). Positive responses to these extracts correlated with total serum IgE levels of the subjects and were significantly associated with the presence of atopic disease. CONCLUSIONS: We have documented sensitization to tropical pollen and spores in our population. Its association with atopy suggests that it has a role in allergic diseases in the tropics.

Adolescent↗
PubMed2000

Uvulopalatopharyngoplasty versus laser assisted uvulopalatoplasty for the treatment of snoring: an objective randomised clinical trial.

This study was designed to evaluate objectively the clinical effectiveness of surgery for snoring and to compare the results of conventional uvulopalatopharyngoplasty (UPPP) and laser assisted uvulopalatoplasty (LAUP) in the treatment of snoring. Patients who had been referred for investigation and treatment of their snoring were randomly allocated to receive either UPPP or LAUP. Forty-seven patients with confirmed palatal flutter had surgery and all of them had a preoperative and postoperative objective assessment of their snoring loudness and duration in the home. The recording device (Snore Box) is simple for the patient to operate, portable with a built in microphone, and able to produce objective results, which can be automatically analysed. Of the 38 patients, who had technically valid recordings, 22 underwent LAUP and 16 UPPP. Overall the mean postoperative Snore Index (SI) was less than the preoperative SI (P < 0.0001), the average difference being 78.2 snores/h. There was no significant difference between the LAUP and UPPP regarding the fall in the SI. This study is the first objective comparative study to demonstrate the effectiveness of snoring surgery.

Adult↗
PubMed2000

Changes in snoring during natural sleep identified by acoustic crest factor analysis at different times of night.

Sleep nasendoscopy can be used to identify the site of snoring but questions remain about how well a short assessment during drug-induced sleep reflects the natural condition. To investigate the uniformity of snoring during natural sleep we studied five patients (three men, two women) referred by their GPs for treatment of their snoring. A digital audio tape recorder captured the free-field snore sound at different times of night in hospital. Acoustic Crest Factor values were calculated on the 15 recordings made, having previously demonstrated that high crest factor values distinguish palatal from non-palatal snoring at sleep nasendoscopy. Some recordings showed reproducibility, but others showed substantial changes between recordings an hour apart. We infer that the snoring mechanism may change in some individuals during the night, with or without a change of snore site. We conclude a single recording, as in sleep nasendoscopy, may not be representative.

Acoustics↗
PubMed2000

Invasive Haemophilus influenzae type b infections in Singapore children: a hospital-based study.

OBJECTIVE: A 6-year (1990-95) hospital-based retrospective study was carried out to investigate the pattern of invasive Haemophilus influenzae type b (Hib) disease. METHODOLOGY: Cases with Hib isolated from sterile sites (blood, cerebrospinal fluid, or joint aspirate) were identified from the hospital's microbiological records, and their reviewed case records. Patients with pyogenic meningitis in the same study period were also identified to estimate the incidence of Hib meningitis. RESULTS: Twelve patients had positive cultures from sterile sites, of whom nine children were less than 5 years of age. These included seven cases of meningitis, one patient with acute epiglottitis, and one case of pneumonia. Three of the seven patients with meningitis had significant long-term sequelae. Our data also suggests a relatively low proportion of ethnic Chinese children with invasive disease. It was estimated that 18.4% to 41.1% of pyogenic meningitis in children admitted to the National University Hospital were due to Hib. The estimated annual attack rate of invasive Hib disease was at most 3.3 per 100 000 children aged less than 5 years (95% confidence interval: 2.6-3.5/100 000). CONCLUSION: : Invasive Hib infections are relatively uncommon in our community. This justifies the need for a cost effectiveness study before a universal Hib vaccination program is implemented.

Child, Preschool↗
PubMed2000

Edible "bird's nest"-induced anaphylaxis: An under-recognized entity?

The Chinese delicacy "bird's nest" is the most common cause of food-induced anaphylaxis requiring hospitalization among Chinese children in Singapore. This investigation has established an immunoglobulin E-mediated cause and has characterized the major putative allergens.

Adolescent↗
PubMed2000

Ethnic differences in genetic susceptibility to atopy and asthma in Singapore.

INTRODUCTION: Asthma and atopy are complex traits, the phenotypes being influenced by the interaction of both genetic and environmental factors. In view of the growing evidence for inter-ethnic differences in genetic susceptibility to complex diseases such as asthma and atopy, we have assessed genetic factors for these diseases in the local population. METHODS: The genetic analysis of asthma and atopy is being approached by candidate gene analysis as well as linkage studies for mapping of susceptibility loci. We reviewed published studies, which include data from our population on some candidate genes, as well as our preliminary data on susceptibility locus mapping for linkage to chromosome 5q31-33. RESULTS: In local studies of the interleukin-4 receptor and tumour necrosis factor polymorphisms, we failed to find associations with genetic variants previously implicated to be associated with asthma and atopy. Evaluation of markers on chromosome 5q31-32 identified novel loci for susceptibility to asthma and atopy in addition to loci already described by others. CONCLUSION: Both the published literature and our own findings indicate that there are inter-ethnic differences in genetic susceptibility to asthma and atopy.

Asian People↗
PubMed1999

Cervical lymph node metastases and squamous cell carcinoma of the lip.

BACKGROUND: Squamous cell carcinoma of the lip generally has a favorable outcome. The chance of long-term survival is significantly reduced if lymph node metastases develop. Any features that could identify patients having increased risks of occult lymph node metastases would allow more aggressive treatment and, possibly, a better outcome. METHODS: A chart review of lip cancer from this institution identified 1001 patients with squamous cell carcinoma of the lip. This database was used to identify the characteristics that are associated with occult lymph node metastases. RESULTS: Delayed cervical lymph node metastases developed in 40 patients. No significant differences were noted in the frequency of delayed lymph node metastases according to gender, lip subsite, or age less than 40 years. Significant differences were noted in association with the tumor size, tumor differentiation, and local recurrence. CONCLUSIONS: Elective cervical lymphadenectomy is justifiable for higher grade tumors and for locally recurrent tumors. An increase in delayed metastases was observed in patients with tumors greater than 3 cm, but the proportion is not great enough to justify elective neck dissections.

Adult↗
PubMed1999

Association of ambient air-pollution levels with acute asthma exacerbation among children in Singapore.

BACKGROUND: Air-pollution levels have been shown to be associated with increased morbidity of respiratory diseases. METHODS: Data for ambient air-pollutant levels, meteorologic factors, and hospitalization or emergency room (ER) visits for acute asthma in Singapore children over a 5-year period (1990-4) were obtained and analyzed for associations by time-series methods. RESULTS: Throughout this period, the annual mean and 24-h mean levels for sulfur dioxide (SO2), nitrogen dioxide (NO2), and total suspended particles (TSP) and maximum 1-h daily average for ozone were generally within the air-quality guidelines established by the World Health Organization (WHO). However, positive correlation between levels of each of these pollutants and daily ER visits for asthma was observed in children aged 3-12 years, but not among adolescents and young adults (13-21 years old). The association with SO2 and TSP persisted after standardization for meteorologic and temporal variables. An adjusted increase in 2.9 ER visits for every 20 microg/m3 increase in atmospheric SO2 levels, lagged by 1 day, was observed on days when levels were above 68 microg/m3. With TSP, an adjusted increase of 5.80 ER visits for every 20 microg/m3 increase in its daily atmospheric levels, lagged by 1 day, was observed on days with levels above 73 microg/m3. Similar results were also obtained after controlling for autocorrelation by time-series analysis. CONCLUSIONS: These associations were observed even though the overall levels of all pollutants were generally within the air-quality guidelines established by the WHO. These findings suggest that asthmatic children are susceptible to increased levels of air pollutants, particularly SO2 and TSP, although the ambient levels are generally within "acceptable" ranges.

Acute Disease↗
PubMed1999

Sensitization to local dust-mite fauna in Singapore.

BACKGROUND: Recent studies showed the presence of a unique dust-mite fauna in the indoor environment of Singapore. Immediate hypersensitivity to these dust mites, along with other known indoor allergens, may play a role in the pathogenesis of allergic respiratory diseases. This study evaluated the sensitization rates of the local atopic population to these allergens. METHODS: The skin prick test was performed on a total of 391 individuals (289 patients with asthma and/or allergic rhinitis and 102 healthy controls) using extracts of six species of local dust mites (Austroglycyphagus malaysiensis, Blomia tropicalis, Dermatophagoides pteronyssinus, D. farinae, Sturnophagoides brasiliensis, and Tyrophagus putrescentiae) and 10 other common indoor allergens. Total serum IgE and specific IgE to these dust mites were also quantified with the fluorescence allergosorbent test (FAST). RESULTS: The sensitization rates among patients with asthma and/or allergic rhinitis to dust mites and other inhalant allergens tested (via skin prick tests) were as follow: B. tropicalis (96.2%), D. pteronyssinus (93.4%), D. farinae (92.3%), A. malaysiensis (78.2%), S. brasiliensis (71.6%), T. putrescentiae (71.3%), canary feathers (69.9%), Periplaneta americana (cockroach) (59.5%), Blattella germanica (cockroach) (56.4%), mosquito (Aedes sp.) (46.4%), dog epithelia (mixed breed) (34.3%), kapok seed (31.8%), cat hair (29.1%), Aspergillus fumigatus (20.8%), Penicillium notatum (18.0%), and Candida (Monilia) albicans (9.3%). All patients were observed to react to at least three of the six dust-mite extracts, with 254/289 (87.9%) reacting to at least five or to all six. Skin prick responses to the dust mites were found to correlate with the corresponding specific IgE levels quantified by FAST (P<0.001). In addition, specific IgE levels to D. pteronyssinus and D. farinae were highly correlated (Spearman's rank coefficient = 0.76, P<0.001), as were those to B. tropicalis and A. malaysiensis (r = 0.60, P<0.001). CONCLUSIONS: Asthma and/or allergic rhinitis patients were highly sensitized to the local dust-mite fauna. Thus, these dust mites should be considered important allergenic sources of this region.

Adolescent↗
PubMed1999

House dust mite fauna of tropical Singapore.

INTRODUCTION AND AIMS: Sensitization to house dust mites is very common in the tropics. This study evaluated the dust mite fauna in Singaporean homes. METHODS: A total of 134 dust samples from 50 homes were evaluated. Dust mites were isolated, identified and quantified by standard techniques. RESULTS: Dust mites were isolated from 130/134 (97%) samples, with mites identified in all samples from sofas (n = 21) and carpets (n = 13), and 49/50 (98%) and 47/50 (94%) from mattresses and bedroom floors, respectively. All samples from sofas and carpets had more than 500 mites/g compared with 47/50 (94%) and 23/50 (46%) from mattresses and floors, respectively. Blomia tropicalis was the predominant mite (62% of total mites) followed by D. pteronyssinus (16% of total mites). Eight samples had a predominance of Sturnophagoides brasiliensis and Tarsonemus granarius. Other species that accounted approximately 1% of mites identified included D. farinae, Austroglycyphagus malaysiensis, Cheyletus malaccensis, Malayoglyphus intermedius, Suidasia pontifica and Tyrophagus putrescentiae. CONCLUSION: Dust mites were highly prevalent and present in high densities in Singaporean homes with B. tropicalis being the most prevalent species.

Animals↗