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Biomedical subjects

Wai Man Chan

Publications and source records attributed to Wai Man Chan.

17 recordsLinked to original sources
PubMed2006

Association of complement factor H polymorphisms with exudative age-related macular degeneration.

PURPOSE: Variants in the complement factor H (CFH) gene have been reported to be associated with age-related macular degeneration (AMD). We conducted a case-control association study to investigate the association of 6 single nucleotide polymorphisms (SNPs) in CFH with exudative AMD in the Chinese population. METHODS: We recruited 163 cases and 244 controls, all ethnic Chinese, with complete ophthalmic examination including fundus investigation. Cigarette smoking was recorded. Six SNPs (dbSNP ID: rs3753394, rs800292, rs1061147, rs1061170, rs380390, and rs1329428) in the CFH gene were genotyped by Taqman assays. RESULTS: Y402H (1277 T>C) has low frequencies in our study population, 5.8% in patients and 3.9% in controls. It was not associated with exudative AMD adjusted for age, gender and smoking. Significant associations were detected for AMD with rs3753394 (p=0.003, p(corr)=0.018), rs800292 (p=0.00053, p(corr)=0.0032), and rs1329428 (p=0.00092, p(corr)=0.0028), p(corr) values obtained after adjustment for multicomparison. A haplotype containing these four SNPs (TGTC) was found to confer a significantly increased likelihood of exudative AMD with an odds ratio of 1.68 (95% CI: 1.26-2.23) p=0.0003 (p(corr)=0.0026 after correction by permutation test). Logistic regression analysis detected no interactions between the SNPs and age, gender or smoking. CONCLUSIONS: We have found differences in the association between the CFH gene and exudative AMD in Chinese from Caucasians and Japanese. We detected SNP rs3753394 in the CFH promoter carrying a significantly increased risk for exudative AMD.

Aged↗
PubMed2006

Effects of triamcinolone on the expression of VEGF and PEDF in human retinal pigment epithelial and human umbilical vein endothelial cells.

PURPOSE: To investigate whether triamcinolone acetonide (TA) affects the expression of vascular endothelial growth factor (VEGF) and pigment epithelial derived factor (PEDF) in human retinal pigment epithelium (ARPE19) and human umbilical vein endothelial (HUVE) cells. Study the time course of the effects of TA on VEGF and PEDF expressions in cultured cells. METHODS: ARPE19 and HUVE cells were grown to subconfluence and treated with TA (0.1 mg/ml, 1 mg/ml). The mRNA expressions of VEGF and PEDF were determined from 10 min to three days using real-time RT-PCR. Concurrently, the protein levels of VEGF and PEDF in ARPE cells were detected with ELISA. RESULTS: Real-time RT-PCR showed TA affected a 0.5 fold decrease in VEGF(165) level and about a 2.5 fold increase in PEDF level at both TA concentrations. The effect was maintained at 12 h at 0.1 mg/ml TA and 24 h at 1 mg/ml TA. Similar changes were observed in the respective protein concentrations. The effects of TA on VEGF and PEDF transcript levels were similar in HUVE and ARPE19 cells. VEGF and PEDF protein productions in HUVE cells were too low for statistical analysis. CONCLUSIONS: TA reduces the expression of VEGF but increases the expression of PEDF in ARPE19 and HUVE cells. These observations suggest TA may influence the inhibition of neovascularization and macular edema through differential VEGF and PEDF expressions.

Cell Line↗
PubMed2006

HTRA1 promoter polymorphism in wet age-related macular degeneration.

Age-related macular degeneration (AMD), the most common cause of irreversible vision loss in individuals aged older than 50 years, is classified as either wet (neovascular) or dry (nonneovascular). Inherited variation in the complement factor H gene is a major risk factor for drusen in dry AMD. Here we report that a single-nucleotide polymorphism in the promoter region of HTRA1, a serine protease gene on chromosome 10q26, is a major genetic risk factor for wet AMD. A whole-genome association mapping strategy was applied to a Chinese population, yielding a P value of <10(-11). Individuals with the risk-associated genotype were estimated to have a likelihood of developing wet AMD 10 times that of individuals with the wild-type genotype.

Aged↗
PubMed2006

Obesity, physical activity, and mortality in a prospective chinese elderly cohort.

BACKGROUND: In older people, it is unclear whether obesity relates to mortality, which calls into question its etiologic role in disease and its public health relevance. This apparent lack of relationship in older people could be an artifactual result of their diverse health states. METHODS: We used Cox regression analysis to determine whether the effect of body mass index (BMI) (calculated as weight in kilograms divided by the square of height in meters) or physical activity on mortality varied with health status in a prospective cohort study of Chinese people 65 years or older enrolled from 1998 to 2000 at all of the 18 Elderly Health Centers of the Hong Kong Government Department of Health. Health status was categorized into 5 morbidity groups using a 12-item index covering illnesses, medications, frailty, and smoking. RESULTS: After a mean follow-up of 4.1 years, there were 3819 deaths in 54 088 subjects (96.5% successful follow-up). The effect of BMI on mortality varied with baseline health status (P<.001). In the healthiest group, obese people (BMI >/=25) had higher mortality (adjusted hazard ratio [HR], 1.54; 95% confidence interval [CI], 1.02-2.33), but in the unhealthiest group they had lower mortality (HR, 0.55; 95% CI, 0.49-0.63) compared with subjects of normal weight. Daily physical activity was associated with lower mortality compared with inactivity in the unhealthiest group (HR, 0.70; 95% CI, 0.61- 0.81) but not in the healthiest group. CONCLUSIONS: In the elderly, the relationship between obesity and mortality varies according to the underlying health status. In those with poor health status, obesity is associated with better outcome, whereas in those with initially good health status, obesity is associated with worse outcome.

Aged↗
PubMed2006

Age- versus time-comparative self-rated health in Hong Kong Chinese older adults.

OBJECTIVES: The main objectives were to examine the relation between age-comparative (self vs others of same age) self-rated health (SRH) and time-comparative (self this year vs last year) SRH, and to evaluate which was more strongly associated with specific physical health problems. METHODS: Cross-sectional data on two SRH measures and various physical health problems from 18749 male and 37413 female clients aged 65 or over from 18 Elderly Health Centres in Hong Kong were analysed using logistic regression with adjustment for potential confounders. RESULTS: Men were more likely to report 'better' and less likely to report 'worse' SRH than women. 'Normal' was the most common option but the proportions choosing this decreased with age on both SRH measures. There was a fairly weak but statistically significant correlation between these two measures, with Kappa coefficients of 0.125 and 0.167 for men and women, respectively. For both men and women, there were significantly positive linear trends between age-comparative SRH options from 'better' to 'worse' and physical health problems, such as respiratory diseases, musculoskeletal diseases, any active chronic diseases, functional disability, depressive symptoms, taking medication regularly, and admission to hospital last year. However, for time-comparative SRH, those who rated 'normal' had the smallest odds ratios in all of the physical health problems above than those who rated 'better' or 'worse'. CONCLUSIONS: The two SRH measures correlated with each other weakly but significantly. Age-comparative SRH was linearly, and time-comparative SRH was curvilinearly associated with physical health problems.

Age Factors↗
PubMed2005

A community model for care of elderly people with diabetes via telemedicine.

A primary care group diabetes care program using telemedicine was developed and its feasibility and acceptability were tested in 22 subjects with Type 2 diabetes mellitus using a one-group, pretest-posttest quasi-experimental design. Compliance with the program was 100%. Significant reductions in total calorie intake as well as body mass index were achieved, with an increase in the percentage of subjects achieving better diabetes control as measured by the 2-hr hemastix. Improvements in diabetes knowledge and disease-specific and generic measures of quality of life were also observed. Most subjects evaluated this mode of service delivery favorably in the questionnaire and focus group discussions. There is potential for the integration of this mode of service delivery into current health services.

Aged↗
PubMed2005

Use of intravitreal triamcinolone acetonide injection in unilateral idiopathic juxtafoveal telangiectasis.

Idiopathic juxtafoveal telangiectasis (IJT) is one of the primary retinal telangiectasia that can result in visual impairment attributed to resultant cystoid macular oedema and rarely, choroidal neovascularization. The authors herein report successful treatment using intravitreal triamcinolone acetonide in a case of unilateral IJT that did not respond to prior laser photocoagulation. Serial optical coherence tomography was used to monitor the effectiveness of intravitreal triamcinolone acetonide in the treatment of IJT.

Fovea Centralis↗
PubMed2004

Obesity and depressive symptoms in Chinese elderly.

OBJECTIVES: The main objective was to examine the association between obesity and depressive symptoms among Chinese elderly in Hong Kong. METHODS: Cross-sectional data on depressive symptoms and body mass index from 56 167 clients aged 65 or over who enrolled as members of Elderly Health Centres from July 1998 to December 2000 were analysed using multiple logistic regression with adjustment of potential confounders. RESULTS: Among 18 750 men and 37 417 women, the prevalence [95% confidence interval (CI)] of depressive symptoms (based on the Geriatric Depression Scale) was 4.9% (4.6-5.2%) and 7.9% (7.6-8.1%) respectively (p < 0.001). The prevalence of obesity (by World Health Organisation Asian standard: body mass index > or =25.0) in women was significantly higher than that of men (42.1% (41.6-42.7%) vs 36.6% (35.9-37.3%), p < 0.001). Obese men and women were about 20% less likely to suffer from depressive symptoms compared with those with normal weight after adjustment for confounders, with odds ratios (95% CI) of 0.82 (0.69-0.97) and 0.78 (0.71-0.86) respectively. Negative linear trends were observed between depressive symptoms and BMI categories in both sexes, and women showed a greater slope and stronger statistical significance than men. CONCLUSIONS: Both obese elderly men and women in Hong Kong were less likely to suffer from depressive symptoms than those of normal weight. The results support the 'jolly fat' hypothesis previously restricted to men, and extend the hypothesis to female elderly. Chinese traditional culture and positive values towards obesity may be protective against depressive symptoms.

Aged↗
PubMed2004

Two cases of X-linked juvenile retinoschisis with different optical coherence tomography findings and RS1 gene mutations.

The optical coherence tomography (OCT) findings, clinical features, and mutations in the RS1 gene of two unrelated patients with X-linked retinoschisis (XLRS) are reported herein. Two Chinese patients with early onset XLRS were given a comprehensive ophthalmologic examination and OCT investigation. The RS1 gene was screened for sequence alterations in all exons and splice regions. The two patients presented with different phenotypic features and OCT findings. One patient with more severe clinical presentation had a RS1 exon 1 deletion and a P193S mutation was found in the other patient with mild macular involvement. OCT demonstrates the markedly different features of XLRS patients with different RS1 mutations. This study strengthens the role of OCT in the diagnosis and monitoring of XLRS.

Adolescent↗
PubMed2003

Treatment of choroidal neovascularization in central serous chorioretinopathy by photodynamic therapy with verteporfin.

PURPOSE: To evaluate the safety and efficacy of photodynamic therapy (PDT) with verteporfin in the treatment of patients with choroidal neovascularization (CNV) secondary to central serous chorioretinopathy (CSC). DESIGN: Open-label, two-center, noncomparative, prospective interventional case series. METHODS: Consecutive patients with subfoveal or juxtafoveal CNV secondary to CSC were recruited and treated with a standard regimen of PDT with verteporfin. At regular 3-month follow-up examinations, re-treatment was considered if fluorescein angiography showed evidence of leakage. Outcome measures included the proportion of patients who had improvement (gained 2 more lines), stable, or loss (dropped in 2 or more lines) in vision at the final follow-up and the changes in best-corrected visual acuity (BCVA) from baseline. RESULTS: Ten eyes of 10 patients were recruited into the study. The mean age of the patients was 57.3 years with a mean follow-up duration of 12.6 months. At the last follow-up, six (60%) eyes gained 2 or more lines of BCVA with four (40%) patients having final BCVA of within 1 line. No patient lost 2 or more lines of BCVA. The mean logarithm of the minimal angle of resolution BCVA improvement after PDT was 2.4 lines (Wilcoxon signed-rank test, P =.013). No patient suffered serious ocular or systemic complications from PDT. CONCLUSIONS: Photodynamic therapy with verteporfin therapy is a safe and well-tolerated treatment in patients with CNV associated with CSC. A randomized, controlled trial with a longer follow-up period is warranted to further study the efficacy of PDT in the management of CNV secondary to CSC.

Aged↗
PubMed2003

A novel PHOX2A/ARIX mutation in an Iranian family with congenital fibrosis of extraocular muscles type 2 (CFEOM2).

PURPOSE: To describe the clinical features of two affected members of an Iranian family with autosomal recessive congenital fibrosis of the extraocular muscles (CFEOM2) and to report their novel mutation in the PHOX2A/ARIX gene. DESIGN: Experimental study. METHODS SETTING: Institutional practice. patient population:Six members of an Iranian family with CFEOM underwent complete ocular examinations including assessment of ocular motility, visual acuity, slit-lamp biomicroscopy, tonometry, and ophthalmoscopy. EXPERIMENTAL PROCEDURE: Mutation analysis of the PHOX2A gene was performed using polymerase chain reaction amplification of the coding exons and direct sequencing of polymerase chain reaction products. MAIN OUTCOME MEASURE: Presence or absence of mutation in PHOX2A gene in two siblings with exotropia and recessive CFEOM. Exotropia and ptosis were corrected surgically in one of the two siblings. RESULTS: The two affected siblings had bilateral ptosis and exotropia and severe limitation of all extraocular movements. One patient underwent strabismus surgery and ptosis repair. PHOX2A mutation analysis revealed a novel nonsense mutation in exon 2 (439C-->T). Both parents and the unaffected siblings were heterozygous,and the two affected siblings were homozygous for this mutation. CONCLUSIONS: The 439C-->T mutation in this family changes a glutamine to a stop codon (Q90X) at the beginning of the PHOX2A homeodomain region. This is the fourth CFEOM2 mutation in PHOX2A and the first nonsense mutation to be identified. It confirms PHOX2A as the autosomal recessive CFEOM2 disease gene and provides evidence that the phenotypic differences between PHOX2A mutations in man and mouse do not result from hypomorphic PHOX2A alleles in humans.

Blepharoptosis↗
PubMed2002

Hepatitis B associated fulminant polyarteritis nodosa: successful treatment with pulse cyclophosphamide, prednisolone and lamivudine following emergency surgery.

For hepatitis B virus associated polyarteritis nodosa, alpha interferon and plasma exchanges have been proposed to be the first-line treatment. We report a case of hepatitis B surface antigen (HBsAg)-positive fulminant polyarteritis nodosa with predominant gastrointestinal involvement who showed good response to pulse cyclophosphamide, prednisolone, and lamivudine therapy. The patient, a 22-year-old man, presented with a short history of epigastric pain. Initial upper gastrointestinal endoscopy revealed gastritis and duodenal erosions. His pain did not respond to H2-receptor antagonists. He had slightly impaired liver function tests, and was HBsAg and hepatitis B e antigen (HBeAg) positive. Around 3 weeks after initial presentation, he developed massive gastrointestinal haemorrhage requiring resuscitation and emergency laparotomy. Microscopic examination of the resection specimens revealed necrotizing vasculitis of small and medium-sized arteries in the submucosa compatible with polyarteritis nodosa. The patient was treated with pulse cyclophosphamide and prednisolone, with lamivudine being added when he showed an acute rise in liver enzymes. He subsequently developed HBeAg seroconversion, and remained well 18 months after cessation of all immunosuppressives. We believe that the efficacy of pulse cyclophosphamide, prednisolone, and lamivudine in the treatment of hepatitis B virus associated polyarteritis nodosa, especially in comparison with interferon and plasma exchanges, deserves further evaluation.

Adult↗
PubMedDate not supplied

ABCA4 sequence variants in Chinese patients with age-related macular degeneration or Stargardt's disease.

ABCA4 gene sequence alterations cause Stargardt's disease (STGD) and may cause some age-related macular degeneration (AMD). We sought to shed light on these associations among Hong Kong Chinese by genotyping 140 AMD, 18 STGD and 95 normal control subjects for 15 ABCA4 exons which were reported to often contain AMD- or STGD-associated mutations. Sequence alterations R212H, T1428M, V1433I, T1572M, I2166M, IVS6-5T>G and IVS33+1G>T were found in AMD patients. T1428M and R2040X occurred in STGD patients. Control subjects displayed all the above missense alterations but no splicing or nonsense changes. Therefore, ABCA4 splicing mutations may be associated with a small proportion of AMD cases.

ATP-Binding Cassette Transporters↗