Young Moo Ro

Gene expression profiling of oxidative stress on atrial fibrillation in humans

Atrial Fibrillation (AF) is thought be caused by oxidative stress. Oxidative stress at the cellular level results from many factors, including exposure to alcohol, medications, cold, toxins or radiation. In this study we investigated gene transcriptional profiles on the human myocardial tissues from AF and oxidative stress conditions. Right atrial appendages were obtained from AF patients (n = 26) undergoing the Maze procedure, and from control patients (n = 26) who were in normal sinus rhythm and undergoing coronary artery bypass graft operation. To examine the effects of oxidative stress on AF, we used radioactive complementary DNA (cDNA) microarrays to evaluate changes in the expression of 1,152 known genes. This technology, which monitors thousands of genes simultaneously, gives us a better picture of the interactions between AF and oxidative stress. Total RNAs prepared from the retrieved tissues were used to synthesize (33)P-labeled cDNAs by reverse transcription and hybridized to cDNA microarrays. Gene expression profiles showed that 30 genes were upregulated and 25 were downregulated in AF patients compared with control patients. Moreover, comparison rank analysis revealed that the expression of five genes related to reactive oxygen species (ROS)-including flavin containing monooxygenase 1, monoamine oxidase B, ubiquitin specific protease 8, tyrosinase-related protein 1, and tyrosine 3-monooxygenase-increased by more than 2.0 of the Z-ratio, and two genes related to anti-oxidants including glutathione peroxidase 1, and heme oxygenase 2-decreased to the Z-ratio levels of <= -2.0. Apparently, a balanced regulation of pro- and anti-oxidation can be shifted toward pro-oxidation and can result in serious damage similar to that of human AF. Western blotting analysis confirmed the upregulation of tyrosinase-related protein 1 and tyrosine 3-monooxygenase and the downregulation of heme oxygenase 2. These results suggested that the gene expression pattern of myocardial tissues in AF patients can be associated with oxidative stress, resulting in a significant increase in ROS. Thus, the cDNA microarray technique was useful for investigating transcription profiles in AF. It showed that the intracellular mechanism of oxidative stress plays a pivotal role in the pathologic progression of AF and offers novel insight into potential treatment with antioxidants.

Associations among plasma adiponectin, hypertension, left ventricular diastolic function and left ventricular mass index

Objective: The purpose of this study was to characterize the relationships among plasma adiponectin, essential hypertension, left ventricular diastolic function and left ventricular hypertrophy. Methods and Results: Plasma adiponectin concentration was assessed by radioimmunoassay, and body mass index (BMI) was measured in 275 patients (138 women and 137 men). Various echocardiographic parameters such as deceleration time (DT) and isovolumetric relaxation time (IVRT) were measured by using echocardiograms. The authors calculated left ventricular mass index (LVMI) and E/A ratio. Pulse wave velocity (PWV) was calculated by dividing the distance between the left subclavian artery ostium and the tip of the femoral sheath with the time interval between two pulse waves. The plasma adiponectin concentration of the hypertensive group was significantly lower than that of the non‐hypertensive group (9.9 ± 9.8 μg/ml vs. 12.9 ± 9.5 μg/ml, p = 0.019). PWV in the hypertensive group was 12.0 ± 3.9 m/s compared with 9.3 ± 2.8 m/s in the normotensive group (p < 0.001). LVMI in the hypertensive group was 135.1 ± 35.4 g/m 2 compared with 100.5 ± 18.7 g/m 2 in the normotensive group (p < 0.001). E/A ratio (0.8 ± 0.3 vs. 1.1 ± 0.4, p = 0.041) was lower in the hypertensive group. DT (200.0 ± 61.2 ms vs. 177.3 ± 40.8 ms, p = 0.048) and IVRT (106.9 ± 25.4 vs. 91.3 ± 27.6 ms, p = 0.243) were higher in the hypertensive group. Plasma adiponectin showed an inverse correlation with LVMI (r = −0.525; p < 0.001) and PWV (r = −0.557; p < 0.001), IVRT (r = −0.485; p = 0.008), and showed a positive correlation with E/A ratio (r = 0.359; p < 0.001). Multiple regression analyses showed that PWV and plasma adiponectin were able to explain the 73.3% of LVMI variability (r = 0.856; p < 0.001). Conclusion: The results suggest that a decrease in plasma adiponectin concentration is associated with the progression of left ventricular hypertrophy with diastolic dysfunction.

Spatial Dispersion of Action Potential Duration Restitution Kinetics Is Associated with Induction of Ventricular Tachycardia/Fibrillation in Humans

Introduction: Action potential duration restitution (APDR) plays a role in initiation and maintenance of ventricular tachycardia (VT)/ventricular fibrillation (VF). We hypothesized that the steeply sloped APDR and its spatial heterogeneity contribute to VT/VF inducibility in patients with ventricular arrhythmia.

Action potential duration restitution kinetics in human atrial fibrillation

OBJECTIVES We undertook this study to determine whether human atrial fibrillation (AF) relates to steeply sloped action potential duration restitution (APDR) kinetics and whether the spatial nonuniformity of APDR promotes persistence of AF. BACKGROUND A steeply sloped APDR curve is known to be an important determinant of the induction of more complex action potential duration (APD) dynamics and fibrillation. METHODS Patients with chronic atrial fibrillation (CAF) (n = 18), paroxysmal atrial fibrillation (PAF) (n = 14) and normal control subjects (n = 9) were studied. The monophasic action potential duration at 90% repolarization (APD(90)) and the effective refractory period (ERP) were measured at six sites in the right atrium. After AF was electrically converted, APDR was assessed by delivering a single extrastimulus after a train of stimuli at a cycle length of 600 ms (S(1)S(2)) at six different sites of the right atrium, as well as rapid pacing at cycle lengths that induced APD alternans. RESULTS The APD(90) and ERP in patients with CAF were shorter than those in patients with PAF and control subjects (p < 0.05); however, the dispersions of APD(90) and ERP in each group were similar. The maximal slopes of APDR by S(1)S(2) and rapid pacing in patients with CAF (1.2 +/- 0.4 and 1.7 +/- 0.2) and PAF (1.1 +/- 0.4 and 1.3 +/- 0.4) were higher than those in control subjects (0.5 +/- 0.3 and 0.8 +/- 0.2, respectively; p < 0.01). The maximal slope obtained by S(1)S(2) did not differ from that obtained by rapid pacing in any group. The inter-regional difference of the maximal slope in patients with CAF (1.6 +/- 0.4, p < 0.05) was greater than that in patients with PAF (1.2 +/- 0.3, p = NS vs. control) and control subjects (0.4 +/- 0.2). CONCLUSIONS Atrial fibrillation was related to steeply sloped (>1) APDR kinetics. The spatial dispersion of APDR in patients with chronic AF was greater than that of patients with paroxysmal AF and control subjects, indicating that the heterogeneity of APDR of the atrium plays an important role in the persistence of AF.

5-azacytidine induces cardiac differentiation of P19 embryonic stem cells.

The P19 embryonal carcinoma cell line is a useful model cells for studies on cardiac differentiation. However, its low efficacy of differentiation hampers its usefulness. We investigated the effect of 5-azacytidine (5-aza) on P19 cells to differentiate into a high-efficacy cardiomyocytes. Embryoid-body-like structures were formed after 6 days with 1 µM of 5-aza in a P19 cell monolayer culture, beating cell clusters first observed on day 12, and, the production of beating cell clusters increased by 80.1% (29 of 36-wells) after 18 days. In comparison, the spontaneous beating cells was 33.3% (12 of 36-wells) for the untreated control cells. In response to 1 µM of 5-aza, P19 cells expressed bone morphogenetic protein-2 (BMP-2), BMP-4, Bmpr1a and Smad1 at day 6 or 9, and also cardiac markers such as GATA-4, Nkx2.5, cardiac troponin I, and desmin were up-regulated in a time-dependent manner after induction of BMP signaling molecules. Immunocytochemistry revealed the expression of smooth muscle a-actin, sarcomeric a-actinin, cardiac myosin heavy chain, cardiac troponin T and desmin, respectively. The proportion of sarcomeric a-actinin positive cells accounted for 6.48% on day 15 after 5-aza exposure as measured by flow cytometry. This study has demonstrated that 5-aza induces differentiation of P19 cells into cardiomyocytes in a confluent monolayer culture in the absence of prior embryoid formation and dimethyl sulfoxide exposure, depending in part on alteration of BMP signaling molecules. These results suggest that 5-aza treatment could be used as a new method for cardiac differentiation in P19 cells.

Multiple predictors of coronary restenosis after drug-eluting stent implantation in patients with diabetes

Objectives: To identify parameters influencing the likelihood of restenosis after implantation of drug-eluting stents (DES) in patients with diabetes. Methods: Stented patients (n  =  840) with DES were retrospectively reviewed for inclusion in the study from the Multicenter PCI Database Registry. From this database, 211 (25.1%) of 840 patients with six-month angiographic follow up had diabetes. Predictors of coronary restenosis were identified with univariate and multivariate logistic regression analyses. Results: Restenosis occurred in 92 of 629 (14.6%) patients without diabetes and in 44 (20.9%) of 211 patients with diabetes (p < 0.001). Multivariate parameters for predicting restenosis in the diabetic group were current smoking (odds ratio (OR) 1.923, 95% confidence interval (CI) 1.055 to 4.725, p  =  0.036), higher C reactive protein concentration (OR 1.031, 95% CI 1.011 to 1.075, p  =  0.043), use of the paclitaxel-eluting stent (OR 2.638, 95% CI 1.338 to 5.200, p  =  0.005), longer stent length (OR 1.065, 95% CI 1.021 to 1.119, p  =  0.033), smaller reference diameter before DES implantation (OR 0.501, 95% CI 0.110 to 0.965, p  =  0.040), smaller reference diameter (OR 0.455, 95% CI 0.120 to 0.814, p  =  0.026) and minimum lumen diameter (OR 0.447, 95% CI 0.068 to 0.876, p  =  0.039) after DES implantation. Conclusion: Even with the introduction of DES, diabetes remains a significant predictor of coronary restenosis, especially in cases of a small baseline vessel size, small vessel size after percutaneous coronary intervention, longer stent length, use of the paclitaxel-eluting stent, current smoking and high C reactive protein concentration.

Percutaneous coronary intervention with drug-eluting stent implantation vs. minimally invasive direct coronary artery bypass (MIDCAB) in patients with left anterior descending coronary artery stenosis

The aim of this study was to assess the effects of percutaneous coronary intervention with drug‐eluting stents (DESs) versus minimally invasive direct coronary artery bypass (MIDCAB) surgery in the management of patients with proximal left anterior descending (LAD) coronary artery stenosis. Until recent years, despite the advantages of percutaneous transluminal coronary angioplasty (PTCA) with bare metal stent implantation, such as shorter hospital stays and recovery time, MIDCAB showed better results with regard to the need for repeated intervention in the target vessel than PTCA with proximal LAD lesions. Symptomatic patients (n = 189) were randomly assigned to DES group (n = 119) and MIDCAB group (n = 70). Patients with an isolated high‐grade lesion (stenosis of ≥ 70% of the luminal diameter) in the proximal LAD coronary artery (from the ostium to the first diagonal branch) were included in this study. During the 6‐month follow‐up period, 1.7% (n = 2) in the DES group needed repeated revascularization procedures for target lesion revascularization compared with 5.9% (n = 4) in the MIDCAB group (P = 0.196). The rates of death and myocardial infarction were similar in both groups [DES 0.0% (n = 0) vs. MIDCAB 2.9% (n = 2), P = 0.135; DES 1.7% (n = 2) vs. MIDCAB 2.9% (n = 2), P = 0.627; respectively] during 6 months of follow‐up. In‐hospital length of stay was significantly shorter in the DES group compared with the MIDCAB group (5.8 ± 2.1 days vs. 8.9 ± 2.6 days; P = 0.001). DES implantation and MIDCAB surgery showed similar rates of myocardial infarction, the need for repeated revascularization, and death during 6 months of follow‐up. However, DES implantation resulted in lower average number of hospital stays and similar postoperative complications. Catheter Cardiovasc Interv 2005;64:75–81.

Differentiation, engraftment and functional effects of pre-treated mesenchymal stem cells in a rat myocardial infarct model.

Background — Mesenchymal stem cells (MSCs) offer a novel therapeutic option in the treatment of acute myocardial infarction. MSCs are able to differentiate into myogenic cells after 5-azacytitdine treatment. However, 5-azacytidine might have genotoxic effects. Recently, it was reported that combined treatment with bone morphogenetic protein-2(BMP-2) and fibroblast growth factor-4(FGF-4) caused cardiac differentiation in non-precardiac mesoderm explants. Therefore, we investigated whether MSCs treated with combined BMP-2 and FGF-4 showed evidence of myogenic differentiation in vitro, and whether these cells resulted in sustained engraftment, myogenic differentiation, and improved cardiac function after implantation in infarcted myocardium. Methods and results — In vitro study: MSCs were treated with BMP-2 + FGF-4 (GF-MSCs) and myogenic phenotype was evaluated immunohistochemically. Cell growth curve was used to compare MSC proliferative capacity between the growth factors and 5-azacytidine treatments. In vivo study: two weeks after coronary artery occlusion, GF-MSCs (n = 15), MSCs (n = 5) labelled with PKH26 were injected into infarcted myocardium. Control animals (n = 5) received a culture medium into the infarcted myocardium.Two weeks after implantation, some engrafted GF-MSCs or MSCs expressed sarcomeric-a-actinin and cardiac myosin heavy chain, as was observed in culture. Echocardiography showed that the GF-MSC group had a better (p < 0.05) left ventricular performance than the other groups. Conclusion — GF-MSCs induced myogenic differentiation in vitro. Moreover, GF-MSCs engrafted into the infarcted myocardium increased myogenic differentiation, prevented dilation of the infarcted region, and eventually improved heart function.

A randomised study comparing the efficacy and safety of rosuvastatin with atorvastatin for achieving lipid goals in clinical practice in Asian patients at high risk of cardiovascular disease (DISCOVERY-Asia study).

ABSTRACT Background: Most studies investigating the benefits of statins have focused on North American and European populations. This study focuses on evaluating the lipid-lowering effects of rosuvastatin and atorvastatin in Asian patients. Objectives: The DIrect Statin COmparison of LDL‐C Values: an Evaluation of Rosuvastatin therapY (DISCOVERY)-Asia study is one of nine independently powered studies assessing the efficacy of starting doses of statins in achieving target lipid levels in different countries worldwide. DISCOVERY-Asia was a 12-week, randomised, open-label, parallel-group study conducted in China, Hong Kong, Korea, Malaysia, Taiwan, and Thailand. Results: A total of 1482 adults with primary hypercholesterolaemia and high cardiovascular risk (> 20%/10 years, type 2 diabetes, or a history of coronary heart disease) were randomised in a 2 : 1 ratio to receive rosuvastatin 10 mg once daily (o.d.) or atorvastatin 10 mg o.d. The percentage of patients achieving the 1998 European Joint Task Force low-density lipoprotein cholesterol (LDL‐C) goal of < 3.0 mmol/L at 12 weeks was significantly higher in the rosuvastatin group (n = 950) compared with the atorvastatin group (n = 471) (79.5 vs. 69.4%, respectively; p < 0.0001). Similar results were observed for 1998 European goals for total cholesterol (TC), and the 2003 European goals for LDL‐C and TC. LDL‐C and TC levels were reduced significantly more with rosuvastatin compared with atorvastatin. Both drugs were well-tolerated and the incidence and type of adverse events were similar in each group. Conclusions: This 12-week study showed that the starting dose of rosuvastatin 10 mg o.d. was significantly more effective than the starting dose of atorvastatin 10 mg o.d. at enabling patients with primary hypercholesterolaemia to achieve European goals for LDL‐C and TC in a largely Asian population in real-life clinical practice. The safety profile of rosuvastatin 10 mg is similar to that of atorvastatin 10 mg in the Asian population studied here, and is consistent with the known safety profile of rosuvastatin in the white population. Trial registration: ClinicalTrials.gov identifier: NCT00241488.

Epicardial ablation of ventricular tachycardia associated with isolated ventricular noncompaction.

A 52‐year‐old man presented with sudden onset of palpitations and dizziness. Echocardiogram confirmed the diagnosis of isolated noncompaction of ventricular myocardium with moderated systolic dysfunction, and the electrocardiogram (ECG) revealed ventricular tachycardia (VT), of which the focus seemed to match an area of prominent left ventricular noncompaction on the 12‐lead surface ECG. Through the activation mapping from the endo‐ and epicardium, simultaneously, a discrete potential preceding the QRS during VT was observed at the anterolateral epicardial wall. He subsequently underwent radiofrequency ablation, and VT was successfully eliminated.