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Biomedical subjects

C W Yu

Publications and source records attributed to C W Yu.

At least 19 recordsLinked to original sources
PubMed2006

Cytokine gene polymorphisms in bullous pemphigoid in a Chinese population.

BACKGROUND: Bullous pemphigoid (BP) is an autoimmune bullous disease mostly associated with autoantibodies to the hemidesmosomal BP autoantigens BP180 and BP230. High levels of interleukin (IL)-1beta, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma have been detected in skin lesions or sera of patients with BP. Cytokine gene polymorphisms may affect cytokine production and contribute to susceptibility to autoimmune diseases. Until now, no cytokine gene polymorphism study has been conducted on patients with BP. OBJECTIVES: We aimed to determine whether the genetic polymorphisms of the cytokine genes might influence the development of BP. METHODS: DNA samples were obtained from 96 BP patients and 174 control subjects. Using direct sequencing and microsatellite genotyping, we examined 23 polymorphisms in 11 cytokine genes including the IL-1alpha, IL-1beta, IL-1 receptor antagonist, IL-4, IL-6, IL-8, IL-10, IL-13, IL-4 receptor, TNF-alpha and IFN-gamma genes. RESULTS: Although the BP patients were more likely to carry the -511T and -31C alleles of the IL-1beta gene (P = 0.04), the significance disappeared after correction for multiple testing (Pc). There was complete linkage disequilibrium between the -511T and -31C alleles of the IL-1beta gene. In female patients with BP, the associations with IL-1beta (-511T) and (-31C) alleles were much stronger (68% vs. 40.6%, odds ratio = 3.11, Pc = 0.006). No significantly different allelic and genotypic distributions of other cytokine gene polymorphisms could be found between the patients with BP and controls. Moreover, no association with the extent of disease involvement (localized or generalized) was observed. CONCLUSIONS: The IL-1beta (-511) and (-31) polymorphisms were significantly associated with BP in women. The other genetic polymorphisms of cytokine genes that we analysed do not appear to be associated with BP susceptibility in our Chinese population.

Adult↗
PubMed2006

Psoriasis vulgaris in Chinese individuals is associated with PSORS1C3 and CDSN genes.

BACKGROUND: Besides the HLA-Cw*0602 allele, the psoriasis susceptibility 1 candidate 3 (PSORS1C3) and corneodesmosin (CDSN) genes are two probable psoriasis susceptibility genes in the PSORS1 locus. The -79C, -26C and +246A alleles of the PSORS1C3 gene, the CDSN*971T allele, CDSN*TTC (619T-1236T-1243C) and CDSN*5 (619T-1240G-1243C) are strongly associated with psoriasis in the caucasian population. Until now, no haplotype study of the PSORS1C3 and CDSN genes has been documented in Chinese patients with psoriasis vulgaris. OBJECTIVES: We aimed to determine whether genetic polymorphisms of the PSORS1C3 and CDSN genes were associated with an increased risk of psoriasis vulgaris in Chinese patients in Taiwan. METHODS: We investigated the PSORS1C3 and CDSN genes for disease association by direct sequencing in 178 patients with psoriasis vulgaris and 203 control subjects. Genotyping for HLA-Cw*0602, alpha-helix coiled-coil rod homologue (HCR) gene and single nucleotide polymorphism (SNP) n.9 was also carried out using a sequence-based typing method. RESULTS: The PSORS1C3*582A allele, an SNP in the 3'-untranslated region of the PSORS1C3 gene, was a major psoriasis vulgaris susceptibility allele in the Chinese population, and the association was much stronger in patients with early-onset psoriasis vulgaris (22.3% vs. 6.9%, odds ratio = 3.87, P(c) =0.0000072). The frequencies of CDSN*TTC and CDSN*971T were also significantly increased in patients with early-onset psoriasis vulgaris. Moreover, PSORS1C3*582A, SNP n.9*C, Cw*0602 and HCR*WWCC were in near complete linkage disequilibrium (LD) with each other; in contrast, the LD with the CDSN gene was not so strong. SNP n.9*C-Cw*0602-PSORS1C3*582A-HCR*WWCC was a major susceptibility haplotype in patients with early-onset psoriasis vulgaris (P < 10(-7)) and this risk haplotype also carried CDSN*TTC and CDSN*971T. CONCLUSIONS: The PSORS1C3 and CDSN genes are important psoriasis susceptibility genes in Chinese patients with psoriasis vulgaris.

Adolescent↗
PubMed2006

No association of cytokine gene polymorphisms in Chinese patients with atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a common chronically relapsing skin disease associated with the activation of T-helper 2 cells. Recent studies have shown that polymorphisms in the genes for interleukin (IL)-4, the IL-4 receptor, IL-13, and signal transducer and activator 6 (STAT6) may contribute to susceptibility of AD. To date, no cytokine gene polymorphism study has been conducted on Chinese patients with AD. AIMS: To determine whether genetic polymorphisms of the cytokine genes might influence the development of AD. METHODS: DNA samples were obtained from 94 patients and 186 control subjects. Using direct sequencing and microsatellite genotyping, we examined 22 polymorphisms in eight cytokine genes including the genes for IL-4, -10, -12B and -13, the IL-4 receptor, tumour necrosis factor (TNF)-alpha, STAT6, and interferon (IFN)-gamma. RESULTS: No significantly different allelic and genotypic distributions of the cytokine gene polymorphisms could be found between patients and controls. Moreover, no association was observed with disease onset, gender, the presence of elevated serum total IgE level or blood eosinophilia. CONCLUSION: Our study suggests that the analysed genetic polymorphisms of cytokine genes do not appear to be associated with AD susceptibility in our Chinese population.

Adolescent↗
PubMed2005

Self-perception of physical competences in preadolescent overweight Chinese children.

OBJECTIVE: To compare self-perceptions of physical competences in overweight and in normal weight preadolescent Chinese children. DESIGN: Cross-sectional study. SETTING: Three primary schools and a university hospital in Hong Kong. SUBJECTS: A total of 634 children, comprising 558 (462 normal weight, 96 overweight) aged 8-12 y randomly sampled from three primary schools, and 76 similar age overweight children recruited from the community for a diet and exercise intervention programme. MEASUREMENTS: Height, weight and percentage body fat were measured. Self-perceptions of physical competences were determined by Physical Self-Descriptive Questionnaire (PSDQ). Corresponding actual physical competences were measured by physical fitness tests. RESULTS: Overweight children perceived themselves to have significantly more body fat than normal weight children, with poorer appearance, sports competence, endurance, coordination, flexibility, overall physical self-concept and self-esteem, but to be no less healthy, no less physically active and no less strong. Overweight children performed less well than normal weight children in measures of endurance, coordination and flexibility but better in strength. Poor self-perception of physical competences appeared only partly related to deficiencies in actual physical competences. CONCLUSION: Overweight children have poorer self-perception of their physical competences but do not perceive themselves to be less strong, healthy or physically active than normal weight children. Exercise programmes for overweight children could be more effective if designed with the knowledge of these self-perceptions.

Body Composition↗
PubMed2004

The association between global self-esteem, physical self-concept and actual vs ideal body size rating in Chinese primary school children.

OBJECTIVE: To investigate whether the discrepancy between actual and ideal body size rating is related to Chinese children's global self-esteem and global physical self-concept. DESIGN: A cross-sectional study of school children who completed questionnaires related to global self-esteem, global physical self-concept, and actual vs ideal body size. SUBJECTS: A total of 386 Chinese children (44% girls and 56% boys) aged 7-13 y from a primary school in Hong Kong, China. MEASUREMENTS: Global self-esteem and physical self-concept were measured using the physical self-descriptive questionnaire. Actual vs ideal body size discrepancy was established using the silhouette matching task. RESULTS: No significant relationship was found between global self-esteem and actual-ideal body size discrepancy of children. Global physical self-concept had a moderate negative correlation (r=-0.12) with the body size discrepancy score and the discrepancy score explained very limited variance (R(2)=0.015; F(1, 296)=4.51; P<0.05) in global physical self-concept. Three body size discrepancy groups (none, positive, and negative) were examined to see if there were any significant differences in global self-esteem, global physical self-concept, and specific dimensions of physical self-concept. A significant overall difference was found between groups for global physical self-concept (F=3.73, P<0.05) and the physical self-concept subscales of physical activity (F=3.25, P<0.05), body fat (F=61.26, P<0.001), and strength (F=5.26, P<0.01). Boys scored significantly higher than girls on global physical self-concept-especially in the sport competence, strength, and endurance subscales. CONCLUSION: This study revealed that the actual-ideal body size discrepancy rating of Chinese children was not predictive of global physical self-concept and global self-esteem. These findings are contrary to those reported in Western children, which may mean that culture plays a role in the formation of body attitude.

Adolescent↗
PubMed2004

Overweight in children is associated with arterial endothelial dysfunction and intima-media thickening.

OBJECTIVE: We sought to study arterial endothelial function and carotid intima-media thickness (IMT), both early markers of atherosclerosis, in overweight compared to normal children. DESIGN: Case-control comparison. SUBJECTS: A total of 36 asymptomatic overweight children (body mass index (BMI)>23; mean 25+/-3) aged 9-12 y and 36 age- and gender-matched nonobese healthy children (BMI<21) from a school community. MEASUREMENTS: The key parameters were: BMI, arterial endothelial function (ultrasound-derived endothelium-dependent dilation) and carotid artery IMT. The secondary parameters measured included body fat content, waist-hip ratio (WHR), blood pressures, blood lipids, insulin and glucose. RESULTS: The two groups were well matched for blood pressures, cholesterol and glucose levels, but BMI (P<0.0001), body fat (P=0.001), WHR (P<0.05), fasting blood insulin (P=0.001) and triglyceride levels (P<0.05) were higher in obese children. Overweight was associated with impaired arterial endothelial function (6.6+/-2.3 vs 9.7+/-3.0%, P<0.0001) and increased carotid IMT (0.49+/-0.04 mm vs 0.45+/-0.04 mm, P=0.006). The degree of endothelial dysfunction correlated with BMI (P<0.003) on multivariate analysis. CONCLUSION: Obesity, even of mild-to-moderate degree, is independently associated with abnormal arterial function and structure in otherwise healthy young children.

Anthropometry↗
PubMed2002

Effects of dietary intervention and strength training on blood lipid level in obese children.

AIMS: To evaluate effects of a low energy diet, with or without strength training, on blood lipid profile in obese children. METHODS: Eighty two obese children were enrolled into a six week dietary programme, and were randomly allocated to a training group or a non-training group. The training group underwent regular exercise sessions with emphasis on strength training. RESULTS: Height increased significantly, with a non-significant reduction in body mass index. Fat free mass increased significantly in the training group. Serum total cholesterol was significantly reduced in both groups. The LDL:HDL ratio significantly decreased in the training group. CONCLUSION: Results support the potentially beneficial effects of both diet and physical training. Further and longer term evaluation of such programmes is required.

Adult↗
PubMed2002

Energy expenditure and physical activity of obese children: cross-sectional study.

OBJECTIVES: To investigate the total daily energy expenditure and physical activity pattern of a group of obese and non-obese Hong Kong children. DESIGN: Cross-sectional study. SETTINGS: University teaching hospital, Hong Kong. PARTICIPANTS: Eighteen obese children aged 6 to 17 years and 18 age- and sex-matched non-obese children in the local Hong Kong community. MAIN OUTCOME MEASURES: Total daily energy expenditure and physical activity pattern were estimated for 3 days using heart rate monitoring. Body composition was measured by dual-energy X-ray absorptiometry. RESULTS: In obese children, both total fat mass and fat-free mass were greater than in non-obese children. Total daily energy expenditure and its sleep and sedentary components were higher in absolute terms (by 42%, 43%, and 126%, respectively) for obese children. When normalised for body weight, the basal metabolic rate was no different between obese and non-obese children, while the total daily energy expenditure of the obese children was significantly lower (by 22%) than that of non-obese children. When normalised for fat-free mass, the basal metabolic rate and the sedentary component of total daily energy expenditure were significantly higher for obese children. Obese children spent 12% less time asleep, but 51% more time in sedentary activity and 30% less time physically active: a ratio of active-to-sedentary waking time of 0.6 for obese children and 1.9 for non-obese children. CONCLUSIONS: Although the basal metabolic rate may be influenced by body composition, the finding of a normal basal metabolic rate when normalised for body weight suggests that an intrinsic difference of metabolic rate is not a major contributory cause of obesity. The study pointed particularly to the potential benefit of increasing physical exercise time relative to sedentary activities to reduce the prevalence of childhood obesity. Obese and non-obese children had similar basal metabolic rates when adjusted by fat-free mass and fat mass. Obese children spent more time in sedentary activities.

Adolescent↗
PubMed2001

A study on beams passing through hip prosthesis for pelvic radiation treatment.

PURPOSE: To study the dose distributions at the interface due to the presence of a metal implant; to show the dose distributions in combined fields in the presence of hip prostheses; and to demonstrate the capabilities and limitations of a conventional system. METHODS AND MATERIALS: Perturbations in the dose distribution caused by a hip prosthesis can result in unacceptable dose inhomogeneities within the target volume and in regions where tissues interface with implant. The Monte Carlo technique and a conventional treatment planning system are used to calculate the dose distributions. RESULTS: Dose increases of 15% in tissue are seen at the interface between metal implant and tissue. Dose reductions of 5-25% or 10-45% are observed in the shadow of the hip prosthesis made of 0.5-3-cm-thick titanium or steel alloy respectively. We compared predicted dose distribution between the Monte Carlo simulation and a commercial treatment planning system (CADPLAN). We found that CADPLAN underestimated the attenuation of hip prostheses. This has led to overestimation of the target dose by 14% for a typical four-field box technique. CONCLUSIONS: An acceptable dose distribution can be achieved with a proper lateral beam weighting and compensation using an eight-field technique. The beam compensation may be applied to achieve an adequate target dose.

Hip Prosthesis↗
PubMed2001

Head-up tilt test without intravascular cannulation in children and adolescents.

Previous studies of head-up tilt test have shown that testing at high degrees lacks specificity in children. We suspected that the high false positive rate might be related to the intravascular catheter and other maneuvers incorporated in the test and therefore studied the sensitivity and specificity of standing and HUT at 80 degrees without any invasive procedure and other maneuvers in children and adolescents. Twenty three patients (11.8+/-2.7 years) with recurrent typical neurally mediated syncope and 35 normal control children (11.6+/-3.0 years) underwent motionless standing for 15 min and tilting to 80 degrees for 30 min. Continuous finger arterial pressure monitoring and ECG were performed during the test. Eight (35%) of the 23 patients developed symptoms of near syncope during motionless standing. Thirteen (57%) of them had positive results at 80 degrees tilting for 30 min. The symptoms of syncope were not always corresponding to excessive haemodynamic changes. None of the controls developed any symptoms or excessive hemodynamic changes. Without intravascular instrumentation and other autonomic maneuvers, active motionless standing or HUT at 80 degrees for 30 min is highly specific but of limited sensitivity for the investigation of vasovagal syncope.

Adolescent↗
PubMed2001

Determination of percentage depth-dose curves for electron beams using different types of detectors.

According to the new AAPM TG-51 dosimetry protocol, reference dosimetry for electron beams is performed at depth of d(ref)=0.6R50-0.1 (cm) instead of d(max) recommended in TG-21. In clinical practice most electron beams are normalized at d(max). Therefore it becomes more important to get an accurate percentage-depth-dose (%dd) curve particularly for higher-energy electron beams in which the depth d(ref) is away from d(max). When ionization chambers are used in determining %dd curves the water-to-air stopping-power ratios and the fluence correction factors are required. The TG-51 recommends that the stopping-power ratios for realistic electron beams be used instead of the monoenergetic stopping-power ratios used in TG-21. This investigation aims to study the effects of those correction factors on the determination of %dd curves. We observed 1% deviations in the value of %dd at d(ref) for 15 and 18 MeV beams between a plane-parallel NACP and a cylindrical IC-10 chamber without considering the fluence correction factors P(fl). We explored a method to derive the fluence correction factors at any depth by using the existing fluence correction data at d(max) and tested its feasibility. We compared %dd curves measured by a diode detector and a NACP chamber with stopping-power ratios recommended by TG-51 and those recommended by TG-21. We found that for 15 and 18 MeV beams the difference in the values of %dd at d(ref) between using those two different stopping-power ratios is about 0.5%. Excellent agreement is found between %dd curves measured by the diode and by the NACP chamber when the stopping-power ratios recommended by TG-51 are used.

Dose-Response Relationship, Radiation↗
PubMed2001

Measurement of body fat using leg to leg bioimpedance.

AIMS: (1) To validate a leg to leg bioimpedance analysis (BIA) device in the measurement of body composition in children by assessment of its agreement with dual energy x ray absorptiometry (DXA) and its repeatability. (2) To establish a reference range of percentage body fat in Hong Kong Chinese children. METHODS: Sequential BIA and DXA methods were used to determine body composition in 49 children aged 7-18 years; agreement between the two methods was calculated. Repeatability for the BIA method was established from duplicate measurements. Body composition was then determined by BIA in 1139 girls and 1243 boys aged 7-16 years, who were randomly sampled in eight local primary and secondary schools to establish reference ranges. RESULTS: The 95% limits of agreement between BIA and DXA methods were considered acceptable (-3.3 kg to -0.5 kg fat mass and -3.9 to 0.6% body fat). The percentage body fat increased with increasing age. Compared to the 1993 Hong Kong growth survey, these children had higher body mass index. Mean (SD) percentage body fat at 7 years of age was 17.2% (4.4%) and 14.0% (3.4%) respectively for boys and girls, which increased to 19.3% (4.8%) and 27.8% (6.3%) at age 16. CONCLUSION: Leg to leg BIA is a valid alternative method to DXA for the measurement of body fat. Provisional reference ranges for percentage body fat for Hong Kong Chinese children aged 7-16 years are provided.

Absorptiometry, Photon↗
PubMed2000

Cerebral blood flow during vasovagal syncope induced by active standing or head up tilt.

BACKGROUND: Vasovagal syncope is usually associated with a sudden drop of blood pressure and/or heart rate. However, occasionally the symptoms of syncope induced by orthostatic stress testing are not associated with obvious haemodynamic changes. The mechanisms of syncope in these patients are not clear. AIM: To evaluate changes in cerebral blood flow velocities during orthostatic stress testing in children and adolescents with vasovagal syncope. METHODS: Electrocardiogram, instantaneous arterial blood pressure, and right middle cerebral artery blood flow velocity were recorded at rest, during active standing, and 80 degrees head up tilt. 32 children and adolescents aged between 7 and 18 years with a history of repeated vasovagal syncope and 23 healthy control subjects were studied. RESULTS: Presyncope occurred in 10 patients during standing, and 13 patients during head up tilt. None of the controls had symptoms during the test. The transcranial Doppler study showed that the symptoms were associated with significant decreases of diastolic cerebral blood flow velocity and an increase of pulsatility. There was no significant change of the systolic cerebral blood flow velocity. The changes of cerebral blood flow velocities occurred in all episodes of presyncope, including those not associated with severe drop of blood pressure or heart rate. CONCLUSIONS: Diastolic cerebral blood flow velocity decreased significantly during episodes of presyncope induced by orthostatic stress. Impairment of autoregulation of cerebral blood flow might play an important role in the pathophysiology of syncope.

Adolescent↗
PubMed1998

Transcription of metallothionein isoform promoters is differentially regulated in cadmium-sensitive and -resistant CHO cells.

Transcription regulation of metallothionein (MT) isoform promoters was investigated in Chinese hamster ovary (CHO) K1 and MT gene amplified, cadmium-resistant (CdR) cells. The transfected promoter of Chinese hamster MTI and MTII genes can be activated in both cell lines by stimulation with Cd or Zn ions, although no MT mRNA can be detected in CHO K1 cells after challenge with metal ions. Neither MT promoter used in this study can be activated by induction with dexamethasone, regardless of whether a sequence homologous to glucocorticoid responsive element is present. During induction by metal ions, differential promoter activities of the MT genes occurs in both CHO K1 and CdR cells where MTII promoter has a stronger activity than that of MTI. As indicated by a time course study in both cell lines, the relative induction ratios of both MTI and MTII promoters are similar at each time interval. This result is consistent with a differential transcriptional factor-promoter interaction for the two MT promoters. By using the CHO K1 and CdR cells as a model system, the occurrence of autoregulation for yeast CUP1 (MT) gene was examined in mammalian cells. Both MT promoters consistently show a lower basal activity but a higher induction ratio in CHO K1 than CdR cells; a result different from that of yeast CUP1 gene. When MTF-1 mRNA was examined, no difference in relative quantity was observed in CHO K1 and in CdR cells treated with metal ions or with metal ions absent.

Animals↗
PubMed1998

Effects of blood transfusion on left ventricular output in premature babies.

OBJECTIVE: To investigate the acute effects of red blood cell transfusion on haemodynamics in preterm babies. SETTING: A neonatal unit in a University Hospital. PATIENTS: Preterm babies whose postnatal age was less than four weeks and who required red blood cell transfusion. MEASUREMENT: Cardiac output and left ventricular systolic function was determined using Doppler echocardiography before, one hour and 24 h after red blood cell transfusion. Blood pressure and haematocrit were also recorded at the same time. Mixed-effects regression model was used to analyse the effect of blood transfusion on left ventricular function and cardiac output. RESULTS: 57 preterm babies were recruited. Univariate analysis showed that cardiac index decreased significantly 24 h after transfusion (P<0.05). Systemic red cell transport increased by an average of 11.1% 24 h after transfusion (P<0.05). Multivariate analysis showed that the cardiac index was negatively associated with haematocrit and the index was higher in male babies. CONCLUSION: There was a significant drop in cardiac index and an increase in systemic red cell transport 24 h after transfusion in premature babies.

Analysis of Variance↗
PubMed1998

Ascertainment of 68,XX double aneuploidy by midtrimester biochemical screening: a case report.

A fetus with 68,XX karyotype was ascertained by an elevated midtrimester MSHCG. By antenatal ultrasound, the only unusual finding was in relation to the placenta. Preterm delivery was mandated by the development of severe preeclampsia. Postmortem examination of the stillborn fetus demonstrated no abnormal physical findings other than bilateral syndactyly of fingers and toes.

Adolescent↗
PubMed1998

Clinical evaluation of ceftibuten in gonorrhea. A pilot study in Hong Kong.

BACKGROUND: The escalating rates of gonococcal resistance to quinolone in Hong Kong have prompted a search for an alternative first-line antimicrobial agent for use in treating uncomplicated gonococcal urethritis. Ceftibuten is an orally active third-generation cephalosporin with potent in vitro activity against Neisseria gonorrhoeae. Its pharmacokinetic properties allow single-dose administration. OBJECTIVE: To evaluate the efficacy, safety, and tolerability of ceftibuten in the treatment of uncomplicated gonorrhea in men. STUDY DESIGN: Ceftibuten was evaluated in an open-label, noncomparative, multicenter study. Eligible men with uncomplicated gonococcal urethritis were treated with a single 400-mg oral dose of ceftibuten and reassessed 1 week and 3 weeks after treatment. The main outcome measures were the isolation of N. gonorrhoeae, patient-reported side effects, and other safety parameters (e.g., blood counts and renal and hepatic function tests). RESULTS: One hundred twenty-five men were enrolled in the study. The overall cure rate was 98.2% (110 of 112 evaluable patients). Adverse events, which occurred in 4.5% of patients, were all mild, well tolerated, and of short duration. No significant changes in laboratory test results were noted. Of the 125 isolates, 4.8% were -lactamase positive. Susceptibility to ofloxacin was found to be low in 59.2% of isolates (MIC 0.1 to < 1g/mL) and 25.6% of isolates were resistant (MIC1g/mL) to ofloxacin. CONCLUSIONS: A single 400-mg oral dose of ceftibuten is highly effective and well tolerated in the treatment of uncomplicated gonococcal urethritis in men.

Adolescent↗