Yuen-Fung Yiu

Queen Mary Hospital, Hong Kong, Hong Kong

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Publications (3)11.4 Total impact

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    ABSTRACT: PURPOSE: Epidemiological studies showed that PR prolongation is associated with increased risk of adverse cardiovascular outcomes. We investigated the relations of PR interval with indices of vascular function and endothelial repair as the underlying mechanisms. METHODS: The study comprised 348 high-risk patients with prior coronary artery disease, ischemic stroke, and/or diabetes mellitus recruited from medical outpatient clinics and 150 healthy subjects without such a history. PR interval was considered prolonged if >200 ms, as determined from resting 12-lead electrocardiogram. Vascular function was assessed by brachial flow-meditated dilatation (FMD) using high-resolution ultrasound. Circulating CD133(+)/KDR(+) endothelial progenitor cell (EPC) levels were measured by flow cytometry. RESULTS: Among healthy subjects, PR interval was inversely associated with FMD (R = -0.20, P = 0.015), but not with the level of circulating CD133(+)/KDR(+) EPC (R = 0.05, P = 0.58). Among high-risk cardiovascular patients, PR prolongation >200 ms was more common compared with healthy subjects (45/348 (13 %) versus 4/150 (3 %), P < 0.001). PR interval was associated inversely with FMD (R = -0.14, P = 0.01) and positively with circulating CD133(+)/KDR(+) EPC level (R = +0.14, P = 0.009). Circulating CD133(+)/KDR(+) EPC level was significantly increased in patients with PR prolongation >200 ms (0.87 ± 0.37 versus 0.68 ± 0.42 (log, ×10(-3)/ml), P = 0.005). Adjusted for potential confounders, increased PR interval remained independently associated with increased CD133(+)/KDR(+) EPC by +0.002 (95 % confidence interval (CI) 0.000 to 0.004 (log, ×10(-3)/ml), P = 0.011) and depressed FMD (B = -0.014 %, 95 % CI -0.027 to -0.002, P = 0.026). CONCLUSIONS: PR prolongation is associated with endothelial dysfunction and evidence of endothelial repair activation in patients with high cardiovascular risk.
    Journal of Interventional Cardiac Electrophysiology 02/2013; · 1.39 Impact Factor
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    ABSTRACT: BACKGROUND: Suboptimal vitamin D status is associated with endothelial dysfunction and an increased risk of cardiovascular diseases but it is unclear whether vitamin D supplementation is beneficial. The aim was to investigate the effect of vitamin D supplementation on endothelial function in patients with type 2 diabetes mellitus (DM). METHODS: In a double-blind, placebo-controlled trial, we randomized 100 type 2 DM patients to vitamin D supplement (5000 IU/day, n = 50) or placebo (controls, n = 50) for 12 weeks. Assessment of vascular function with brachial artery flow-mediated dilatation (FMD), circulating levels of endothelial progenitor cells (EPCs) and brachial-ankle pulse wave velocity, and metabolic parameter, high-sensitivity C-reactive protein (hsCRP) and oxidative stress markers were performed before and after the supplementation. RESULTS: After 12 weeks, vitamin D treated patients had significant increases in serum 25-hydroxyvitamin D [25(OH)D] concentration (treatment effect 34.7 ng/mL, 95% CI 26.4-42.9, P < 0.001) and serum ionized calcium (treatment effect 0.037 mmol/L, 95% CI 0.007-0.067, P = 0.018); decreased serum parathyroid hormone concentration (treatment effect -0.55 pmol/L, 95% CI -1.08 to -0.02, P = 0.042) compared to patients who received placebo. Nevertheless, vitamin D supplementation did not improve vascular function as determined by FMD, circulating EPC count or baPWV (all P > 0.05). Furthermore, hsCRP, oxidative stress markers, low- and high-density lipoprotein and glycated hemoglobin were also similar between two groups (all P > 0.05). CONCLUSION: In patients with type 2 DM, 12 weeks oral supplementation of vitamin D did not significantly affect vascular function or serum biomarkers of inflammation and oxidative stress. CLINICAL TRIAL NUMBER: HKCTR-867, www.hkclinicaltrials.com.
    Atherosclerosis 12/2012; · 3.71 Impact Factor
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    ABSTRACT: Vitamin D (Vit-D) deficiency is associated with type 2 diabetes mellitus (DM) and endothelial dysfunction. The relationship of Vit-D deficiency with circulating endothelial progenitor cells and endothelial dysfunction in type 2 DM patients nonetheless remains unclear. We aimed to investigate the cross-sectional association of Vit-D status with brachial flow-mediated dilation (FMD) and circulating endothelial progenitor cell (EPC) numbers in type 2 DM patients. We conducted a cross-sectional study of 280 patients (59% male, aged 68 ± 10 yr) with type 2 DM recruited in outpatient clinics during the winter period. We measured serum 25-hydroxyvitamin D [25(OH)D] by an ELISA kit, circulating CD34+/kinase insert domain-containing receptor (KDR)+ and CD133+/KDR+ EPCs by flow cytometry and brachial artery FMD by vascular ultrasound, respectively. The mean serum 25(OH)D concentration was 25.00 ± 9.17 ng/ml, and 34.3% of patients had Vit-D deficiency [25(OH)D < 20 ng/ml]. Serum 25(OH)D concentration had a significant correlation with hemoglobin A1c level [B = -0.018, 95% confidence interval (CI) -0.035 to -0.002, P = 0.032]. Patients with Vit-D deficiency status had significantly lower brachial FMD (mean difference -1.43%, 95% CI -2.31 to -0.55, P = 0.001) and CD133+/KDR+EPC counts (mean difference -0.12%, 95% CI -0.21 to -0.019, P = 0.022) than those with sufficient Vit-D status after adjustment for age, sex, and cardiovascular risk factors, including hemoglobin A1c levels. Our results demonstrate that serum 25(OH)D status was significantly associated with brachial artery FMD and circulating CD133+/KDR+EPCs. This suggests that Vit-D deficiency might contribute to depletion of EPCs and endothelial dysfunction in patients with type 2 DM.
    The Journal of Clinical Endocrinology and Metabolism 02/2011; 96(5):E830-5. · 6.31 Impact Factor