Ting-Hsing Chao

Effects of oxidative stress on endothelial function after a high-fat meal

Postprandial lipaemia is known to cause endothelial dysfunction, but its underlying mechanism is still under debate. The present study was undertaken to investigate the effects of postprandial lipaemia on endothelial dysfunction and oxidative stress. We measured plasma glutathione peroxidase (GSH-Px), an antioxidant enzyme, and the urinary excretion of 8-epi-prostaglandin F2alpha (8-PGF2alpha), a free radical-catalysed product from the oxidative modification of arachidonic acid, in 16 healthy subjects (mean age, 30 +/- 5 years) without major coronary risk factors. Plasma high-sensitive C-reactive protein, soluble intercellular cell-adhesion molecule-1 and vascular cell-adhesion molecule-1 were also measured. High-resolution ultrasound was used to assess the flow-mediated vasodilatation (FMD) of the brachial artery. Blood and urine samples were collected before and 2, 4 and 6 h after a standard high-fat meal (3677 J, containing 50 g of fat). Serum triacylglycerol (triglyceride) increased and FMD decreased significantly after a high-fat meal. Plasma GSH-Px significantly decreased from 27.2 +/- 12.3 microg/ml to 25.7 +/- 11.8 microg/ml (P=0.022) 2 h after the meal, and urinary excretion of 8-PGF2alpha significantly increased from 1286 +/- 1401 pg/mg of creatinine to 2197 +/- 1343 pg/mg of creatinine (P=0.014) at 4 h after the meal. However, there were no significant changes in the levels of high-sensitive C-reactive protein and adhesion molecules after a high-fat meal. In conclusion, endothelial dysfunction was observed after consuming a high-fat meal and is associated with augmented oxidative stress manifested by the depletion of serum antioxidant enzymes and increased excretion of oxidative modification products.

Pathway for differentiation of human embryonic stem cells to vascular cell components and their potential for vascular regeneration.

Objective— We demonstrated previously that mouse embryonic stem (ES) cell–derived vascular endothelial growth factor receptor-2 (VEGF-R2)–positive cells can differentiate into both vascular endothelial cells and mural cells. This time, we investigated kinetics of differentiation of human ES cells to vascular cells and examined their potential as a source for vascular regeneration. Methods and Results— Unlike mouse ES cells, undifferentiated human ES cells already expressed VEGF-R2, but after differentiation, a VEGF-R2-positive but tumor rejection antigen 1-60 (TRA1-60)–negative population emerged. These VEGF-R2-positive but tumor rejection antigen 1-60–negative cells were also positive for platelet-derived growth factor receptor &agr; and &bgr; chains and could be effectively differentiated into both VE-cadherin+ endothelial cell and &agr;-smooth muscle actin+ mural cell. VE-cadherin+ cells, which were also CD34+ and VEGF-R2+ and thought to be endothelial cells in the early differentiation stage, could be expanded while maintaining their maturity. Their transplantation to the hindlimb ischemia model of immunodeficient mice contributed to the construction of new blood vessels and improved blood flow. Conclusions— We could identify the differentiation process from human ES cells to vascular cell components and demonstrate that expansion and transplantation of vascular cells at the appropriate differentiation stage may constitute a novel strategy for vascular regenerative medicine.

Augmentation of Neovascularizaiton in Hindlimb Ischemia by Combined Transplantation of Human Embryonic Stem Cells-Derived Endothelial and Mural Cells

Background We demonstrated that mouse embryonic stem (ES) cells-derived vascular endothelial growth factor receptor-2 (VEGF-R2) positive cells could differentiate into both endothelial cells (EC) and mural cells (MC), and termed them as vascular progenitor cells (VPC). Recently, we have established a method to expand monkey and human ES cells-derived VPC with the proper differentiation stage in a large quantity. Here we investigated the therapeutic potential of human VPC-derived EC and MC for vascular regeneration. Methods and Results After the expansion of human VPC-derived vascular cells, we transplanted these cells to nude mice with hindlimb ischemia. The blood flow recovery and capillary density in ischemic hindlimbs were significantly improved in human VPC-derived EC-transplanted mice, compared to human peripheral and umbilical cord blood-derived endothelial progenitor cells (pEPC and uEPC) transplanted mice. The combined transplantation of human VPC-derived EC and MC synergistically improved blood flow of ischemic hindlimbs remarkably, compared to the single cell transplantations. Transplanted VPC-derived vascular cells were effectively incorporated into host circulating vessels as EC and MC to maintain long-term vascular integrity. Conclusions Our findings suggest that the combined transplantation of human ES cells-derived EC and MC can be used as a new promising strategy for therapeutic vascular regeneration in patients with tissue ischemia.

G-33A Mutation in the Promoter Region of Thrombomodulin Gene and Its Association With Coronary Artery Disease and Plasma Soluble Thrombomodulin Levels

Thrombomodulin is an endothelial glycoprotein that decreases thrombin activity and activates protein C. A recent study has shown that G-33A promoter mutation of the thrombomodulin gene occurs particularly in Asians. In this study, we analyzed the distribution of G-33A mutation in the promoter region of the thrombomodulin gene in the Chinese population and determined whether the mutation might be a risk for coronary artery disease (CAD). In addition, the influence of this mutation on plasma soluble thrombomodulin levels in patients with CAD was also examined. We studied 320 consecutive patients (mean age 63 years; 73% men) with CAD and 200 age- and sex-matched control subjects. Screening for thrombomodulin G-33A promoter mutation was conducted using polymerase chain reaction, single-strand conformation polymorphism, and direct deoxyribonucleic acid sequencing. The frequency of the G-33A mutation (GA+AA genotypes) was significantly higher in the CAD group (23.8% vs 15.5%, odds ratio [OR] 1.70, p = 0.031). Multiple logistic regression analysis showed that the mutation was an independent risk factor (OR 1.81, p = 0.016) for CAD, as was hypertension (OR 1.44, p = 0.040), diabetes mellitus (OR 2.50, p <0.001), and smoking (OR 2.15, p <0.001). In CAD patients with GG genotype, the soluble thrombomodulin level increased with the extent of CAD (36 +/- 15 vs 47 +/- 18 vs 55 +/- 36 ng/ml in 1-, 2-, or 3-vessel CAD, p <0.001). However, in CAD patients with G-33A mutation, there was no difference between the levels of soluble thrombomodulin (39 +/- 17 vs 37 +/- 15 vs 42 +/- 18 ng/ml, p = NS) in 1-, 2-, or 3-vessel CAD. Our observations suggest that there is a significant association of the G-33A mutation in thrombomodulin gene with CAD, and this mutation may influence the soluble thrombomodulin levels in patients with CAD.

Platelet-activating factor-acetylhydrolase A379V (exon 11) gene polymorphism is an independent and functional risk factor for premature myocardial infarction

Summary.  Background: Oxidation of low density lipoproteins is an initial step of atherogenesis that generates pro‐inflammatory phospholipids, including platelet‐activating factor (PAF). PAF is degraded by PAF‐acetylhydrolase (PAF‐AH), which has been postulated to be a risk factor for myocardial infarction (MI). The role of PAF‐AH for the onset of premature MI is unclear. Methods: Polymorphisms located in putatively functional regions were investigated in a cohort of patients having premature MI onset prior to 46 years of age (n = 200) and a sex‐age‐matched control group (n = 200). The activity of PAF‐AH and coronary angiograms were evaluated for the severity of coronary atherosclerosis. Results: The V allele of A379V (exon 11) polymorphism on PAF‐AH gene was more frequent in patients with premature MI (P = 0.001). This V allele polymorphism was also associated with a lower activity of plasma PAF‐AH and a more complex coronary atherosclerosis (p Trends <0.05). Multiple logistic regression analysis showed that this polymorphism was an independent risk factor (Odds Ratio [OR] 1.66, 95% CI 1.14.1 to 5.80, P = 0.008) as well as smoking (OR 3.72, 95% CI 1.77 to 9.28, P = 0.001), diabetes mellitus (OR 2.25, 95% CI 1.40 to 5.32, P = 0.007) and hypertension (OR 1.88, 95% CI 1.25 to 5.36, P = 0.003) for the onset of premature MI. Conclusion: We conclude that a functional and significant association between the A379V polymorphism on exon 11 of PAF‐AH gene and premature MI exists in this Taiwanese population. This polymorphism is significantly associated with the PAF‐AH activity and the severity of coronary atherosclerosis.

Plasma vascular endothelial growth factor as a marker for early vascular damage in hypertension

Elevation of plasma VEGF (vascular endothelial growth factor) has been noted in patients with hypertension or atherosclerosis. VEGF has been regarded as a marker for endothelial dysfunction. However, the role of VEGF in hypertension-induced vascular injury and its relationship with endothelial function have not been studied. This study included 20 untreated hypertensive men with grade 1 or 2 hypertensive retinopathy, 10 untreated hypertensive men without hypertensive retinopathy and 10 healthy controls. None of the hypertensive patients had diabetes, renal impairment or overt vascular diseases. Plasma VEGF and adhesion molecules were measured using ELISAs. Endothelial function was measured by FMD (flow-mediated vasodilation) of the brachial artery. Plasma levels of VEGF, excluding adhesion molecules, were significantly higher in hypertensive patients with retinopathy when compared with patients without retinopathy (152.4+/-80.8 pg/ml versus 104.7+/-27.2 pg/ml, P = 0.035) or controls (152.4+/-80.8 pg/ml versus 98.9+/-23.7 pg/ml, P = 0.025). Levels of FMD were significantly lower in hypertensive patients than controls, but there were no significant differences between patients with or without retinopathy. Degrees of FMD were inversely correlated with VEGF levels (r = -0.351, P = 0.031). Elevation of plasma VEGF was associated with hypertensive retinopathy. Plasma VEGF could be used as a marker of early vascular damage induced by hypertension.

The 161TT genotype in the exon 6 of the peroxisome-proliferator-activated receptor γ gene is associated with premature acute myocardial infarction and increased lipid peroxidation in habitual heavy smokers

PPAR (peroxisome-proliferator-activated receptor) is a nuclear receptor. Activation of PPARgamma by its ligands could modulate gene transcription, thereby leading to multiple anti-atherogenic and fibrinolytic effects. However, the association between the 161T allele in exon 6 of the PPARgamma gene and premature AMI (acute myocardial infarction) is not clear. We recruited 146 patients with premature AMI (onset age < or =50 years) and 146 controls. The C161T polymorphism was examined using PCR and restriction-fragment-length polymorphism. Plasma levels of Ab-ox-LDL (antibody against oxidized low-density lipoprotein) were measured in 27 male smokers, whose genotypes have been identified. The frequency of the PPARgamma TT genotype among patients with AMI was significantly higher than that in controls [13% compared with 5.5%; OR (95% CI) 2.7, (1.1-6.5), where OR and CI are odds ratio and confidence interval respectively]. This association was not observed in CC or CT genotypes. Using multivariate logistic regression analyses, we found that the homozygous TT genotype [OR (95% CI), 3.1 (1.2-7.9)], smoking [OR (95% CI), 3.5, (2.1-6.0)], hypertension [OR (95% CI), 3.6, (1.9-6.9)] and diabetes mellitus [OR (95% CI), 3.5 (1.5-8.4)] were independent risk factors for premature AMI. Plasma levels of Ab-ox-LDL were significantly higher in healthy volunteers with the TT genotype compared with those with the CC genotype (49.3+/-18.1 compared with 24.2+/-15.2 units/l respectively; P=0.02). Therefore in our study we observed an association between the PPARgamma 161 TT genotype and premature AMI. Lipid peroxidation was significantly influenced by the 161T allele.

Remodeling of carotid arteries is associated with increased expression of thrombomodulin in a mouse transverse aortic constriction model.

Thrombomodulin (TM) is an endothelial glycoprotein that functions as a thrombin cofactor in the activation of protein C. Recent evidence has revealed that TM has unique effects on cellular proliferation, adhesion, and inflammation. We examined TM expression in the arterial remodeling process with different shear conditions. Quantitative real-time reverse transcription-PCR (Q-PCR) revealed that shear stress (25 dyne/cm(2) for 6 hours) induced a 2.6 +/- 0.4-fold increase in TM mRNA levels in endothelial cell culture. Adult FVB (Friend leukemia virus B strain) mice underwent transverse aortic constriction (TAC) between the right (RCA) and left carotid artery (LCA). Doppler (n = 8), morphometric (n = 8), and Q-PCR (n = 8 or 10) studies were performed on carotid arteries at different time points. The RCA lumen and media area increased. The LCA wall shear stress decreased after TAC. RCA wall shear stress increased at day 7 followed by a decrease to the baseline at day 28. TM mRNA level in the LCA was decreased by 61% at day 7 after TAC (0.39 +/- 0.04; p < 0.05 vs. baseline). It progressively returned to the baseline at day 14 (0.85 +/- 0.12) and day 28 (1.48 +/- 0.05; all p = NS). TM appeared in the media of the RCA; TM mRNA level in the RCA was increased by 11-fold at day 14 after TAC (11.0 +/- 0.22) and progressively decreased at day 28 (5.34 +/- 0.25, all p < 0.05 vs. baseline). Our studies suggested that altered shear stress induced significant TM gene expression changes during the arterial remodeling process.

2017 Taiwan lipid guidelines for high risk patients

In Taiwan, the prevalence of hyperlipidemia increased due to lifestyle and dietary habit changes. Low density lipoprotein cholesterol (LDL-C) and non-high density lipoprotein cholesterol (non-HDL-C) are all significant predicting factors of coronary artery disease in Taiwan. We recognized that lipid control is especially important in patients with existed atherosclerotic cardiovascular diseases (ASCVD), including coronary artery disease (CAD), ischemic stroke and peripheral arterial disease (PAD). Because the risk of ASCVD is high in patients with diabetes mellitus (DM), chronic kidney disease (CKD) and familial hypercholesterolemia (FH), lipid control is also necessary in these patients. Lifestyle modification is the first step to control lipid. Weight reduction, regular physical exercise and limitation of alcohol intake all reduce triglyceride (TG) levels. Lipid-lowering drugs include HMG-CoA reductase inhibitors (statins), cholesterol absorption inhibitors (ezetimibe), proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, nicotinic acids (niacin), fibric acids derivatives (fibrates), and long-chain omega-3 fatty acids. Statin is usually the first line therapy. Combination therapy with statin and other lipid-lowering agents may be considered in some clinical settings. For patients with acute coronary syndrome (ACS) and stable CAD, LDL-C < 70 mg/dL is the major target. A lower target of LDL-C <55 mg/dL can be considered in ACS patients with DM. After treating LDL-C to target, non-HDL-C can be considered as a secondary target for patients with TG ≥ 200 mg/dL. The suggested non-HDL-C target is < 100 mg/dL in ACS and CAD patients. For patients with ischemic stroke or transient ischemic attack presumed to be of atherosclerotic origin, statin therapy is beneficial and LDL-C < 100 mg/dL is the suggested target. For patients with symptomatic carotid stenosis or intracranial arterial stenosis, in addition to antiplatelets and blood pressure control, LDL-C should be lowered to < 100 mg/dL. Statin is necessary for DM patients with CV disease and the LDL-C target is < 70 mg/dL. For diabetic patients who are ≥ 40 years of age, or who are < 40 years of age but have additional CV risk factors, the LDL-C target should be < 100 mg/dL. After achieving LDL-C target, combination of other lipid-lowering agents with statin is reasonable to attain TG < 150 mg/dL and HDL-C >40 in men and >50 mg/dL in women in DM. LDL-C increased CV risk in patients with CKD. In adults with glomerular filtration rate (GFR) < 60 mL/min/1.73m2 without chronic dialysis (CKD stage 3-5), statin therapy should be initiated if LDL-C ≥ 100 mg/dL. Ezetimibe can be added to statin to consolidate the CV protection in CKD patients. Mutations in LDL receptor, apolipoprotein B and PCSK9 genes are the common causes of FH. Diagnosis of FH usually depends on family history, clinical history of premature CAD, physical findings of xanthoma or corneal arcus and high levels of LDL-C. In addition to conventional lipid lowering therapies, adjunctive treatment with mipomersen, lomitapide, or PCSK9 inhibitors become necessary to further reduce LDL-C in patients with FH. Overall, these recommendations are to help the health care professionals in Taiwan to treat hyperlipidemia with current scientific evidences. We hope the prescription rate of lipid lowering drugs and control rate of hyperlipidemia in high risk patients could be increased by implementation of the clinical guidelines. The major purpose is to improve clinical outcomes of these high risk patients through the control of hyperlipidemia.

Trends in the Incidence and Management of Acute Myocardial Infarction From 1999 to 2008: Get With the Guidelines Performance Measures in Taiwan

Background The American Heart Association Get With the Guidelines (GWTG) program has improved care quality of acute myocardial infarction (AMI) with important implications for other countries in the world. This study evaluated the incidence and care of AMI in Taiwan and assessed the compliance of GWTG in Taiwan. Methods and Results We used the Taiwan National Health Insurance Research Database (1999–2008) to identify hospitalized patients ≥18 years of age presenting with AMI. The temporal trends of annual incidence and care quality of AMI were evaluated. The age‐adjusted incidence of AMI (/100 000 person‐years) increased from 28.0 in 1999 to 44.4 in 2008 (P<0.001). The use of guideline‐based medications for AMI was evaluated. The use of dual antiplatelet therapy (DAPT) increased from 65% in 2004 to 83.9% in 2008 (P<0.001). Angiotensin‐converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) was used in 72.6% in 2004 and 71.7% in 2008 (P=NS) and β‐blocker was used in 60% in 2004 and 59.7% in 2008 (P=NS). Statin use increased from 32.1% to 50.1% from 2004 to 2008 (P<0.001). The in‐hospital mortality decreased from 15.9% in 1999 to 12.3% in 2008 (P<0.0001). Multivariable analysis showed that DAPT, ACE inhibitor/ARB, β‐blocker, and statin use during hospitalization were all associated with reduced in‐hospital mortality in our AMI patients. Conclusions AMI incidence was increasing, but the guideline‐based medications for AMI were underutilized in Taiwan. Quality improvement programs, such as GWTG, should be promoted to improve AMI care and outcomes in Taiwan.