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Biomedical subjects

W B Chan

Publications and source records attributed to W B Chan.

At least 19 recordsLinked to original sources
PubMed2006

Metabolic syndrome by the international diabetes federation definition in Hong Kong Chinese.

In this report, we aimed to examine the impact of the new International Diabetes Federation (IDF) definition on the prevalence and clinical characteristics of subjects with metabolic syndrome (MES). Data were obtained from a prevalence survey for cardiovascular risk factors in a Hong Kong Chinese working population. There were 1513 subjects well representing all occupational groups from managers to general laborers [910 (60.1%) men and 603 (39.9%) women (mean age 37.5+/-9.2, median 37.0, range 18-66 years)]. The crude prevalence of MES defined by the IDF criterion was 7.4% (compared to other criteria: NCEP, 9.6%; WHO, 13.4% and EGIR, 8.9%). The age-standardized prevalence of MES by the IDF criterion was 8.8% in women and 7.3% in men. Subjects with MES defined by IDF criterion had higher body mass index and waist compared to those with MES defined by NCEP or WHO criteria, and lower triglyceride compared to those with MES defined by NCEP criterion after adjustment for age, gender and smoking. Non-MES subjects defined by IDF criterion had higher 2h glucose and insulin resistance compared to non-MES subjects defined by WHO. In conclusion, the new IDF criterion for MES is easy to implement in clinical practice. It may be potentially more 'specific' in identifying subjects with MES although compared to the NCEP criterion, it may have missed a proportion of subjects, especially men, who have metabolic derangement. Prospective and interventional studies are needed to validate the prognostic values of this new definition in comparison with other existing definitions.

Adolescent↗
PubMed2006

Mesenteric fat thickness as an independent determinant of fatty liver.

OBJECTIVE: Mesenteric fat is drained by the portal circulation and has been suggested to be a key component in obesity-related health risk, notably the metabolic syndrome. There are increasing epidemiological and experimental data showing that fatty liver is another component of this multifaceted syndrome. Given their intimate anatomical and physiological relationships, we hypothesized that mesenteric fat thickness may be independently associated with the risk of fatty liver. To test this hypothesis, we examined the predictive role of various fat deposits including mesenteric fat thickness, and various metabolic variables on the risk of fatty liver. SUBJECTS AND METHODS: A total of 291 Chinese subjects (134 men and 157 women with a mean BMI of 23.7 kg/m2, range: 16.5-33.4 kg/m2) underwent ultrasound examination for measurement of mesenteric, subcutaneous and preperitoneal fat thickness, and for diagnosis of fatty liver. Body mass index, waist circumference, and waist-hip ratio were recorded. Blood pressure was measured. Fasting plasma glucose, insulin resistance, high-density lipoprotein cholesterol (HDL-C), triglycerides, low-density lipoprotein cholesterol (LDL-C), liver enzymes were determined by common methods. RESULTS: The subjects with fatty liver had greater abdominal fat thickness and higher anthropometric indexes than those without fatty liver. The subjects with fatty liver also showed higher blood pressure, worse lipid and glycaemic profile compared with those without fatty liver. Using multiple logistic regression analysis, mesenteric fat thickness was a risk factor of fatty liver, independent of body mass index, age, sex, insulin resistance, fasting plasma glucose, lipid and blood pressure. The odds ratio was 1.5 (95% confidence interval: 1.27-1.77) for every 1 mm increase in the mesenteric fat thickness. Measurement of preperitoneal and subcutaneous fat deposits did not show significant associations with fatty liver. CONCLUSION: Mesenteric fat thickness measured on ultrasound is an independent determinant of fatty liver.

Abdominal Fat↗
PubMed2006

Angiotensin-converting enzyme (ACE) inhibition in type 2, diabetic patients-- interaction with ACE insertion/deletion polymorphism.

Angiotensin-converting enzyme (ACE) insertion(I)/deletion (D) polymorphism may modify the effect of inhibition of the renin-angiotensin-aldosterone system (RAAS) on survival and cardiorenal outcomes in type 2, diabetes. A consecutive cohort of 2089 Chinese type 2 diabetic patients with mean (+/- standard deviation) age of 59.7 +/- 13.1 years were genotyped for this polymorphism by polymerase chain reaction method and were followed prospectively for a median period of 44.6 (interquartile range: 23.7, 57.5) months. Clinical outcomes, including all-cause mortality, cardiovascular and renal end points, were examined. The frequency for I allele was 67.1 and 32.9% for D allele, with observed genotype frequencies of 45.8, 42.6, and 11.6% for 3, DI and DD, respectively. ACE DD polymorphism was an independent predictor for renal end point with hazard ratio (HR) (95% confidence interval) of 1.72 (1.16, 2.56), but not for cardiovascular end point or mortality. After controlling for confounding factors, including ACE I/D genotype, the usage of RAAS inhibitors was associated with reduced risk of mortality (HR 0.34 (0.23, 0.50)) and renal end point (HR 0.55 (0.40, 0.75)). On subgroup analysis, the beneficial effects on survival (II vs DI vs DD: HR 0.29 (0.16, 0.51) vs 0.25 (0.14, 0.46) vs 1.33 (0.41, 4.31)) and renoprotection (II vs DI vs DD: 0.52 (0.30, 0.90) vs 0.43 (0.25, 0.72) vs 0.95 (0.43, 2.12)) were most evident in II and DI carriers. In conclusion, inhibition of RAAS was associated with reduced risk of mortality and occurrence of renal end point in Chinese type 2 diabetic patients. These benefits were most evident among II and DI carriers.

Aged↗
PubMed2006

Vascular defect beyond the endothelium in type II diabetic patients with overt nephropathy and moderate renal insufficiency.

There is a paucity of data on the effects of overt nephropathy and moderate renal impairment on endothelial function in diabetic patients. A total of 26 type II diabetic (DM) patients with nephropathy (DMN+) (mean +/- s.d. age: 63.7 +/- 6.3 years), 32 diabetic patients without nephropathy (DMN-) (59.4 +/- 10.1 years), and 52 non-diabetic subjects (54.9 +/- 8.2 years) were recruited. High-resolution ultrasound scan was used to measure carotid intima media thickness (IMT) and flow-mediated dilation (FMD) of the brachial artery. Endothelium-independent dilation was determined by maximal vascular dilation after sublingual nitroglycerine (glyceryl trinitrate (GTN)-induced dilation). The mean carotid IMT increased progressively from non-DM to DMN- to DMN+ groups (0.74 +/- 0.23 vs 0.80 +/- 0.25 vs 1.03 +/- 0.38 mm; P=0.001 for trend) whereas FMD- (4.3 +/- 2.5 vs 3.9 +/- 1.7 vs 1.9 +/- 2.0%, P<0.001 for trend) and GTN-induced dilation (14.7 +/- 4.0 vs 14.5 +/- 3.9 vs 10.3 +/- 3.2%; P<0.001 for trend) declined in an opposite manner. On multivariate analysis, age (beta=0.257, P=0.009), glomerular filtration rate (beta=-0.364, P<0.001), and smoking (beta=0.25, P=0.013) were independently associated with carotid IMT (F=15.76, R(2)=0.340, P<0.001). After adjustment for baseline brachial arterial diameter, history of smoking (beta=-0.039, P<0.001), fasting plasma glucose (beta=-0.033, P=0.002), and total cholesterol (beta=-0.023, P=0.024) were independently associated with vessel diameter after FMD (F=2446.5, R(2)=0.992, P<0.001); whereas age (beta=-0.069, P=0.001) and urinary albumin excretion (beta=-0.048, P=0.018) were independently associated with vessel diameter after GTN (F=851.6, R(2)=0.967, P<0.001). Type II diabetic patients with overt nephropathy and moderate renal impairment had both structural and functional vascular abnormalities beyond the endothelium.

Aged↗
PubMed2005

The preferred magnetic resonance imaging planes in quantifying visceral adipose tissue and evaluating cardiovascular risk.

BACKGROUND: Magnetic Resonance Imaging (MRI) is a well-accepted non-invasive method in the quantification of visceral adipose tissue. However, a standard method of measurement has not yet been universally agreed. OBJECTIVES: The objectives of the present study were 2-fold, firstly, to identify the imaging plane in the Chinese population which gives the best correlation with total visceral adipose tissue volume and cardiovascular risk factors; and secondly to compare the correlations between single-slice and multiple-slice approach with cardiovascular risk factors. METHODS: Thirty-seven Chinese subjects with no known medical history underwent MRI examination for quantifying total visceral adipose tissue volume. The visceral adipose tissue area at five axial imaging levels within abdomen and pelvis were determined. All subjects had blood pressure measured and fasting blood taken for analysis of cardiovascular risk factors. Framingham risk score for each subject was calculated. RESULTS: The imaging plane at the level of 'lower costal margin' (LCM) in both men and women had the highest correlation with total visceral adipose tissue volume (r = 0.97 and 0.99 respectively). The visceral adipose tissue area at specific imaging levels showed higher correlations with various cardiovascular risk factors and Framingham risk score than total visceral adipose tissue volume. The visceral adipose tissue area at 'umbilicus' (UMB) level in men (r = 0.88) and LCM level in women (r = 0.70) showed the best correlation with Framingham risk score. CONCLUSIONS: The imaging plane at the level of LCM is preferred for reflecting total visceral adipose tissue volume in Chinese subjects. For investigating the association of cardiovascular risk with visceral adipose tissue in MRI-obesity research, the single-slice approach is superior to the multiple-slice approach, with the level of UMB in men and LCM in women as the preferred imaging planes.

Abdomen↗
PubMed2004

Association of carotid intima-media thickness with mesenteric, preperitoneal and subcutaneous fat thickness.

Carotid intima-media thickness (IMT) is an established surrogate marker for atherosclerosis. We have previously reported that abdominal fat, notably mesenteric fat, was a major explanatory variable for multiple cardiovascular risk factors. Given the intimate relationships between visceral fat, cardiovascular risk factors and atherosclerosis, we hypothesize that there are independent relationships between mesenteric fat and carotid IMT. Two hundred and eighty-two Chinese subjects (M: 129, F: 153; mean body mass index (BMI): 23.8 kg/m(2); age range: 20-68 years) were recruited. Maximum carotid IMT as well as maximum mesenteric, preperitoneal and subcutaneous fat thickness were measured by carotid and abdominal ultrasound examinations, respectively. Obesity index and conventional cardiovascular risk factors were assessed by physical examination and blood taking. On univariate analysis, mesenteric but not preperitoneal fat thickness was the major correlate with carotid IMT in both men and women. There was also a weak correlation between carotid IMT and subcutaneous fat thickness in women. On multivariate analysis, mesenteric fat thickness was an independent determinant of carotid IMT after adjustment for subcutaneous and preperitoneal fat thickness, age, gender, blood pressure, insulin resistance, lipid and glycaemic parameters. The association of mesenteric fat thickness with carotid IMT appeared stronger in women than in men, which however was not confirmed on multivariate analysis. In conclusion, mesenteric fat thickness measured on ultrasound showed significant association with carotid IMT, lending further support to the linking role of portal adipose tissue in obesity-related atherosclerosis. Effect of gender on the relationships of mesenteric fat with atherosclerosis risk require further elucidation. Measurement of mesenteric fat thickness may be a useful indicator of regional fat distribution in the assessment of cardiovascular risks.

Adipose Tissue↗
PubMed2004

Increased leptin concentrations and lack of gender difference in Type 2 diabetic patients with nephropathy.

UNLABELLED: Leptin plays an important role in the regulation of body weight and energy balance. Women have higher circulating leptin level than men. In this study, we examined serum leptin concentrations in Type 2 diabetic men and women with or without nephropathy. Fasting plasma glucose (FPG), lipid profile, and serum leptin concentrations were measured in 34 Type 2 diabetic patients with nephropathy (DMN), 12 normoalbuminuric Type 2 diabetic subjects (DM) and 34 non-diabetic control subjects, all matched for age and body mass index (BMI). RESULT: Patients with diabetic nephropathy had lower high-density lipoprotein cholesterol and higher triglyceride, FPG, urinary albumin/creatinine ratio (ACR) and serum creatinine than the other two groups. There was a significant trend in serum leptin concentrations (P<0.001, analysis of variance ANOVA) across the three groups with the main difference being detected between DMN and control subjects (DMN: 17.5 +/- 16.8 ng/ml, DM: 14.6 +/- 10.5 ng/ml and control: 9.1 +/- 7.1 ng/ml). Women had higher serum leptin concentration than men in the control group (12.5 +/- 7.3 ng/ml versus 4.2 +/- 2.0 ng/ml, P=0.001) and in the DM group (18.9 +/- 11 ng/ml versus 8.6 +/- 5.9 ng/ml, P=0.07) whereas this gender difference was not observed in the DMN group (18.6 +/- 17.0 ng/ml versus 16.8 +/- 17.0 ng/ml, P=0.754). On multivariate analysis, ACR (=0.411, P<0.001) and BMI (=0.240, P=0.002) were independently associated with serum leptin concentrations (R2=0.194, F=22.1, P<0.001) in the whole group. In the DMN group, ACR (=0.370, P=0.016) was the only independent determinant of serum leptin concentrations (R2=0.159, F=11.4, P=0.016). Serum leptin concentrations were higher in Type 2 diabetic patients with nephropathy than normoalbuminuric diabetic patients and controls. Diabetic men with nephropathy had proportionally higher serum leptin such that the gender difference in leptin observed in non-nephropathic individuals was abolished.

Adult↗
PubMed2004

The associations of body mass index, C-peptide and metabolic status in Chinese Type 2 diabetic patients.

BACKGROUND: Chinese Type 2 diabetic subjects are generally less obese than their Caucasian counterparts. We hypothesized that lean and obese Chinese Type 2 diabetic subjects have different metabolic and insulin secretory profiles. We compared the clinical features, C peptide and metabolic status between lean/normal weight and obese diabetic subjects. STUDY DESIGN: We conducted a cross-sectional study on 521 consecutive diabetic subjects newly referred to a Diabetes Clinic in 1996. The subjects were categorized into underweight (< 18.5 kg/m(2)), normal weight (18.5-23 kg/m(2)) and overweight (>/= 23 kg/m(2)) according to the re-defined WHO criterion for obesity in Asia Pacific Region. Metabolic and anthropometric parameters were compared between groups with different levels of obesity. RESULTS: In this cohort, 5.8, 30.6 and 63.7% of subjects were underweight, normal weight and overweight, respectively, using the 'Asian' criteria. Of these 521 subjects, 20% had fasting C-peptide less than 0.2 nmol/l, suggesting insulin deficiency. Fasting C-peptide showed linear increasing trend (P < 0.001) while HbA(1c) showed decreasing trend (P = 0.001) with BMI after adjustment for duration of disease. There were more subjects in the underweight group who were treated with insulin (41.3% vs. 13.9 and 8.2%, P < 0.001). Although homeostasis model assessment was similar amongst the three groups, systolic (P = 0.006) and diastolic blood pressure (P < 0.001) and triglyceride (P < 0.001) showed increasing, while HDL-C (P < 0.001) showed decreasing, trends across different BMI groups. The underweight patients had the lowest C-peptide and highest HbA(1c) while overweight patients had the highest C-peptide, blood pressure, triglyceride but lowest HbA(1c) levels. CONCLUSION: In Chinese Type 2 diabetic patients, lean subjects had predominant insulin deficiency and obese subjects had features of metabolic syndrome. Clinicians should have low threshold to initiate insulin therapy in lean Type 2 diabetic patients with suboptimal glycaemic control. In obese diabetic patients, aggressive control of multiple cardiovascular risks is of particular importance.

Adolescent↗
PubMed2004

A patient with low free T4 and low thyroid-stimulating hormone without hypopituitarism.

A 39-year-old entertainer was referred in November 2000 for suspected secondary hypothroidism found during a routine insurance check. Thyroid stimulating hormone (TSH) was 0.30 mIU/L (NR 0.47-4.68 mIU/L) and total T4 was 21.6 nmol/l (NR 57.9-154.4 nmol/l). She had enjoyed good past health and gave birth to a baby girl at 32 weeks gestation in July 2000. She was clinically euthyroid and there was no goiter. Menses was regular with oral contraception. Thyroid function was rechecked with free T4 7.9 pmol/1 (NR 10.2-19.6 pmol/1) and TSH 5.44 mIU/l (NR 0.3-4 mIU/l). Further inquiry revealed that she had been taking a weight reducing drug since December 1999 for fear of potential weight gain during pregnancy. This was identified to be Tri-iodothyroacetic acid (Triac). Serial thyroid function tests showed gradual recovery of thyroid function after Triac was stopped.

Adult↗
PubMed2004

Panhypopituitarism in association with interferon-alpha treatment.

A 30-year-old woman presented in March 2000 with a six-year history of oligomenorrhoea followed by amenorrhoea. She was a known hepatitis B carrier and received interferon-alpha therapy from 1994 to 1997. She developed oligomenorrhoea three months after commencing interferon therapy. Endocrine investigation showed panhypopituitarism. Magnetic resonance (MR) imaging showed a 2 x 3 mm cyst at the posterior aspect of the anterior pituitary gland. She was treated with cortisol, thyroxine and sex hormone replacement. Repeat MR imaging 10 months later showed the same pituitary cyst with no interval change. In conclusion, a case of irreversible panhypopituitarism, associated with interferon-alpha therapy, is reported.

Adult↗
PubMed2003

Triglyceride, albuminuria and blood pressure are the major associations of non-fatal cardiovascular disease in Chinese type 2 diabetes.

Diabetes is associated with an increased risk of cardiovascular disease (CVD). We studied risk factors for CVD in a cohort of Chinese type 2 diabetic patients recruited between July 1994 and August 1998. Ischemic heart disease (IHD) was defined as a history of: (i) confirmed coronary artery disease (with typical electrocardiographic changes or a positive exercise tolerance test) in patients under care of a cardiologist; (ii) documented myocardial infarction; or (iii) coronary interventions such as angioplasty or coronary artery bypass graft. Cerebrovascular accident (CVA) was defined as any definite cerebral vascular event with or without residual neurological deficit. CVD was defined as a history of IHD or CVA. The study enrolled 3333 patients, including 1370 men (41.1%) and 1963 women (58.9%) of mean age 55.9+/-13.3 years (range, 16-91 years; median, 57 years). A total of 279 patients (8.4%) had CVD (including 4.1% with CVA, 4.9% with IHD, and 0.6% with both CVA and IHD). Men had an overall higher rate of CVD than women (10.1% vs. 7.1%, p=0.002). All cardiovascular diseases showed a progressive increase in prevalence with increasing age with the peak among those aged </=60 years. Logistic regression analysis was used to examine the predictive value of age, body mass index, waist-to-hip ratio, blood pressure, fasting plasma glucose, glycated hemoglobin, lipid profiles, albuminuria, smoking and family history of diabetes on the risk of CVD. In women, age, systolic blood pressure and triglyceride level and in men, age and albuminuria, were predictive for CVD. In conclusion, 8.4% of Hong Kong Chinese type 2 diabetic patients being followed in a hospital out-patient setting have a history of established and confirmed cardiovascular disease. Age, systolic blood pressure, triglyceride and albuminuria were the major independent risk factors for non-fatal cardiovascular diseases.

Adolescent↗
PubMed2003

Sonographic measurement of mesenteric fat thickness is a good correlate with cardiovascular risk factors: comparison with subcutaneous and preperitoneal fat thickness, magnetic resonance imaging and anthropometric indexes.

OBJECTIVE: Visceral fat, notably mesenteric fat, which is drained by the portal circulation, plays a critical role in the pathogenesis of metabolic syndrome through increased production of free fatty acids, cytokines and vasoactive peptides. We hypothesize that mesenteric fat thickness as measured by ultrasound scan could explain most of the obesity-related health risk. We explored the relationships between cardiovascular risk factors and abdominal fat as determined by sonographic measurements of thickness of mesenteric, preperitoneal and subcutaneous fat deposits, total abdominal and visceral fat measurement by magnetic resonance imaging (MRI) and anthropometric indexes. DESIGN: A cross-sectional study. SUBJECTS: Subjects included 18 healthy men and 19 women (age: 27-61 y, BMI: 19-33.4 kg/m(2)). MEASUREMENTS: The maximum thickness of mesenteric, preperitoneal and subcutaneous fat was measured by abdominal ultrasound examination. MRI examinations of whole abdomen and pelvis were performed and the amount of total abdominal and visceral fat was quantified. The body mass index, waist circumference and waist-hip ratio were recorded. Cardiovascular risk factors were assessed by physical examination and blood taking. RESULTS: Men had more adverse cardiovascular risk profile, higher visceral fat volume and thicker mesenteric fat deposits than women. Among all the investigated obesity indexes, the mesenteric fat thickness showed the highest correlations with total cholesterol, LDL-C, triglycerides, fasting plasma glucose, HbA(1c) and systolic blood pressure in men, and with triglycerides and HbA(1c) in women. On stepwise multiple regression analysis with different obesity indexes as independent variables, 30-65% of the variances of triglycerides, total cholesterol, LDL-C and HbA(1c) in men, and triglycerides in women were explained by the mesenteric fat thickness. CONCLUSION: Compared with sonographic measurement of subcutaneous and preperitoneal fat thickness, MRI measurement of total abdominal and visceral fat and anthropometric indexes, sonographic measurement of mesenteric fat thickness showed better associations with some of the cardiovascular risk factors. It may potentially be a useful tool to evaluate regional distribution of obesity in the assessment of cardiovascular risk.

Adipose Tissue↗
PubMed2003

Oral alendronate increases bone mineral density in postmenopausal women with primary hyperparathyroidism.

The effect of biphosphonate therapy on bone mineral density (BMD) in patients with primary hyperparathyroidism (PHP) is unknown. Forty postmenopausal women (mean age, 70 yr) with PHP were randomized to receive alendronate 10 mg/d or placebo for 48 wk, followed by treatment withdrawal for 24 wk. The mean (+/-SD) changes in BMD at femoral neck (+4.17 +/- 6.01% vs. -0.25 +/- 3.3%; P = 0.011) and lumbar spine (+3.79 +/- 4.04% vs. 0.19 +/- 2.80%; P = 0.016) were significantly higher with alendronate at 48 wk. Serum calcium was reduced with alendronate but not placebo (-0.09 vs. +0.01 mmol/liter; P = 0.018). Serum bone-specific alkaline phosphatase activity was lower with alendronate from 12 wk onward and increased 24 wk after treatment withdrawal (21.1 +/- 12.8 to 7.3 +/- 4.9 IU/liter at 48 wk, and 15.0 +/- 14.8 IU/liter 24 wk after withdrawal; P = 0.002 for trend). Osteocalcin concentration decreased at 48 wk and increased 24 wk after alendronate withdrawal (P = 0.019 for trend of change over time) but not with placebo. Urinary N-telopeptide/creatinine ratio decreased with alendronate at 48 wk and increased 24 wk after treatment withdrawal (P = 0.008 for trend). N-telopeptide/creatinine ratio did not change with placebo. Alendronate improves BMD and reduces bone turnover markers in postmenopausal women with PHP.

Administration, Oral↗
PubMed2003

Hyperkalaemia in a patient with Graves' disease.

A case of hyporeninaemic hypoaldosteronism in a young girl with treated Graves' disease presenting as hyperkalaemia is described. The possible autoimmune link of these two conditions is discussed.

Adult↗