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Search Results: 1 - 10 of 14336 matches for " Woo-Young Chung "
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Immediate impact of exercise on arterial stiffness in humans  [PDF]
Jae-Bin Seo, Woo-Young Chung, Sang-Hyun Kim, Myung-A Kim, Joo-Hee Zo
World Journal of Cardiovascular Diseases (WJCD) , 2013, DOI: 10.4236/wjcd.2013.31009

Background and objectives: Increased arterial stiffness is an accepted cardiovascular risk factor. Several studies have shown that regular exercise is associated with reduced arterial stiffness. However, the acute effect is not well known. The aim of this study was to evaluate the immediate impact of exercise on arterial stiffness measured by pulse wave velocity (PWV). Subjects and Methods: Data from 100 consecutive patients who underwent graded maximal aerobic exercise test and pulse wave velocity study due to chest pain were analyzed. Results: With respect to brachial-ankle pulse wave velocity (baPWV), it decreased after the exercise test (before vs. after; 1420 ± 260 vs. 1358 ± 245, 1428 ± 255, vs. 1360 ±239 cm/sec; left and right, respectively). Upper extremity systolic blood pressure did not change from baseline. However, upper extremity diastolic blood pressure increased slightly. In addition, lower extremity blood pressure decreased in both systolic and diastolic phases. In both normotensives and hypertensives, baPWV decreased after exercise test. Conclusion: Exercise immediately decreases arterial stiffness.

A case of successful survival from ventricular free wall micro-rupture without surgery  [PDF]
Jae-Bin Seo, Ki-Hyun Jeon, Jin-Hyun Park, Sang-Hyun Kim, Joo-Hee Zo, Myung-A Kim, Woo-Young Chung
World Journal of Cardiovascular Diseases (WJCD) , 2013, DOI: 10.4236/wjcd.2013.32029

We report a case of successful survival from ventricular free wall rupture without surgery, which was not overt rupture but micro-rupture. The patient was diagnosed with acute myocardial infarction (AMI) and underwent primary percutaneous coronary intervention (PCI). Myocardial blood leakage could be detected on transthoracic echocardiography with intravenous infusion of contrast dye 3 days after PCI. This examination revealed that there was not overt perforation but diffuse fissure. Because of his critical condition, he was treated conservatively without surgery. Nevertheless, he survived eventually.

The prevention of contrast induced nephropathy by sarpogrelate in patients with chronic kidney disease: a study protocol for a prospective randomized controlled clinical trial
Kyungil Park, Woo-Young Chung, Jae-Bin Seo, Sang-Hyun Kim, Joo-Hee Zo, Myung-A Kim, Young-Bae Park
Trials , 2010, DOI: 10.1186/1745-6215-11-122
Abstract: The present study aims to investigate differences in occurrence of CIN after sarpogrelate premedication in patients with chronic kidney disease (CKD). 268 participants, aged 20-85 years with a clinical diagnosis of CKD will be recruited. They will be randomly allocated to one of two conditions: (i) routine treatment without sarpogrelate, and (ii) routine treatment with sarpogrelate (a fixed-flexible dose of 300 mg/day). The primary outcome is the occurrence of CIN during 4 weeks after receiving contrast agent.As of May 2010, there were no registered trials evaluating the therapeutic potentials of sarpogrelate in preventing for CIN. If sarpogrelate decreases the worsening of renal function and occurrence of CIN, it will provide a safe, easy and inexpensive treatment option.NCT01165567Contrast-induced nephropathy (CIN) is a common form of hospital-acquired acute renal failure (ARF) after coronary angiography (CAG) and percutaneous coronary intervention (PCI) and is associated with prolonged hospitalization and adverse clinical outcomes [1,2]. Patients undergoing PCI have a higher mortality rate if the nephropathy develops [3]. Although its incidence is low in patients with normal renal function, it can be much higher in those with renal insufficiency at baseline [4,5]. Adequate prophylaxis is needed to reduce the higher morbidity and mortality associated with CIN in high-risk patients. A variety of therapeutic interventions, including saline hydration, diuretics, mannitol, calcium channel antagonists, theophylline, endothelin receptor antagonists, and dopamine, have been used in an attempt to prevent CIN [6-9]. Hydration with normal saline solution is the most widely accepted preventive intervention [9,10]. But the nephropathy occurred in 20~30% who received the recommend treatment [11,12], it means current treatments are not enough and the optimal strategy to prevent CIN has not been established.Although the pathogenesis of this condition is not fully understood, it
Cyclic Bis-1,3-dialkylpyridiniums from the Sponge Haliclona sp.
Yoonyeong Lee,Kyoung Hwa Jang,Ju-eun Jeon,Woo-Young Yang,Chung J. Sim,Ki-Bong Oh,Jongheon Shin
Marine Drugs , 2012, DOI: 10.3390/md10092126
Abstract: Eight novel cyclic bis-1,3-dialkylpyridiniums, as well as two known compounds from the cyclostellettamine class, were isolated from the sponge Haliclona sp. from Korea. Structures of these novel compounds were determined using combined NMR and FAB-MS/MS analyses. Several of these compounds exhibited moderate cytotoxic and antibacterial activities against A549 cell-line and Gram-positive strains, respectively. The structure-activity relationships of cyclostellettamines are discussed based on their bioactivities.
The association between arterial stiffness and left ventricular filling pressure in an apparently healthy Korean population
Hack-Lyoung Kim, Moon-Sun Im, Jae-Bin Seo, Woo-Young Chung, Sang-Hyun Kim, Myung-A Kim, Joo-Hee Zo
Cardiovascular Ultrasound , 2013, DOI: 10.1186/1476-7120-11-2
Abstract: A total of 115 healthy subjects without known cardiovascular risk factors or overt heart disease who underwent both transthoracic echocardiography and brachial-ankle pulse wave velocity (baPWV) measurement at the same day during their routine check-ups were analyzed.The mean age of study subjects was 52.8 ± 8.4 years, and 78 (67.8%) were men. The mean baPWV value was 1,325 ± 185 cm/s. Study subjects were divided into 3 groups according to E/E’ value: subjects with E/E’ < 8, 8–12.9 and E/E’ ≥ 13. As E/E’ increased, baPWV value increased gradually: baPWV in subjects with E/E’ < 8, E/E’ 8–12.9 and E/E’ ≥ 13, were 1,261 ± 163, 1,345 ± 169, 1,569 ± 232 cm/s, respectively (p < 0.001). In multiple linear regression analyses, baPWV was significantly associated with E/E’ (β = 0.371, p < 0.001) after controlling confounders including age, sex and body mass index. In receiver-operating characteristic (ROC) curve analysis, the sensitivity and specificity for detection of E/E’ ≥ 10 were 78.6% and 59.8%, respectively with mean baPWV of 1,282 cm/s as the cut off value. The discriminatory capacity for predicting E/E’ ≥ 10 was improved from an area under the ROC curve of 0.646 with age alone to 0.734 when baPWV was added (p < 0.001).There is a significant association between baPWV and E/E’ in an apparently healthy Korean population. BaPWV is useful as a simple and non-invasive method for early detection of increased LV filling pressure among these people.Stiffened artery increases pulse pressure leading to left ventricular hypertrophy and coronary artery disease [1]. Arterial stiffness has been reported to be associated with cardiovascular morbidity and mortality [2,3].There are several methods to estimate arterial stiffness. Among them, pulse wave velocity (PWV) is generally accepted as the most simple, non-invasive and validated indicator of arterial stiffness [4,5]. Recently, the brachial-ankle PWV (baPWV) measurement, which is easy to perform, has become available in clinical pr
Presenilins are required for maintenance of neural stem cells in the developing brain
Woo-Young Kim, Jie Shen
Molecular Neurodegeneration , 2008, DOI: 10.1186/1750-1326-3-2
Abstract: During mammalian neural development, neural progenitor cells (NPCs) divide and populate the progenitor pool in the ventricular zone (VZ) of the developing telencephalon [1]. There are two phases of neurogenesis. The first phase spans from embryonic day 8.5 (E8.5) to 10.5, during which neural progenitor population expands. The second phase commences around E11.5, reaches peak by E15.5, and then diminishes by E17.5, generating most of the cortical neurons through eleven cell cycles [2-6]. During the first phase, neural progenitor cells are columnar, connecting the pial surface and the apical surface, and predominantly undergo symmetric cell division to expand rapidly the self-renewal founder progenitor cells [6,7]. During the second phase, neural progenitors in the ventricular zone predominantly undergo asymmetric cell division to generate self-renewal daughter progenitor cells that remain in the cell cycle and committed postmitotic neural precursor daughter cells that will ultimately differentiate into neurons or glia [3,7-10]. Notch receptors are required for neural progenitor cell proliferation [11-13]. In the cell cycle of this asymmetric cell division, at the transition from S phase to M phase, the dividing neural progenitor cells displace their nuclei and subsequently migrate from the basal membrane to the apical surface of the neuroepithelium, a phenomenon termed interkinetic nuclear migration (INM) [14,15].Presenilin-1 (PS1) and presenilin-2 (PS2) are the major causative genes of familiar Alzheimer disease (FAD) [16]. Presenilin (PS) is an essential component of the γ-secretase complex, and Notch is one of the physiological substrates of γ-secretase [17]. Notch is one of the most important regulators of neural development in organisms from insects to mammals [18-20]. During mammalian neural development, activation of the Notch signaling pathway is involved in the maintenance of neural progenitor identity and the decision of cell fate [21]. Presenilin is requir
Additive Value of B-Type Natriuretic Peptide on Rest -Dipyridamole Stress -Sestamibi Gated Myocardial SPECT in Patients with Normal Left Ventricular Systolic Function
Jung-Ju Sir,Young-Seok Cho,Woo-Young Chung,Bon-Kwon Koo,In-Ho Chae,Dong-Ju Choi,Hyo-Soo Kim,Byung-Hee Oh,Young-Bae Park
Cardiology Research and Practice , 2010, DOI: 10.4061/2010/642045
Abstract: We evaluated whether BNP has additive value to SPECT in patients with normal left ventricular (LV) systolic function. Data from 224 consecutive patients who underwent rest -dipyridamole stress -sestamibi gated SPECT and coronary angiography due to chest pain were analyzed. Patients with true positive SPECT showed significant higher BNP level than those with false positive defect (38.5 (19.0–79.8) versus 19.0 (9.3–35.8), ). Patients with true negative SPECT also showed significantly lower BNP level than those with false negative SPECT (39.0 (23.0–77.0) versus 22.0 (15.0–43.0), ). In multivariate analyses, elevated BNP level (using a cut-off value of 23.0?pg/mL) was the strongest and independent predictor of CAD in overall patients (OR 2.75, 95% CI: 1.50–5.023, ) and patients with positive SPECT (OR 3.34, 95% CI: 1.51–7.37, ). The area under the receiver-operating characteristic curve for CAD in overall patients and patients with positive SPECT was 0.673 (95% CI: 0.603–0.743, ) and 0.694 (95% CI: 0.602–0.786, ), respectively. This study suggests that BNP level has additive diagnostic value to SPECT findings in predicting CAD in patients with normal LV systolic function. 1. Introduction Previous studies have reported that B-type natriuretic peptide (BNP), synthesized as pre-proBNP mainly in the ventricular myocardium and secreted in response to ventricular volume and pressure overload, has close relation with angiographic severity and could be a potential biomarker for myocardial ischemia even in patients with preserved LV systolic function [1–4]. In patients with coronary artery disease, myocardial ischemia may cause transient left ventricular (LV) systolic and diastolic dysfunction and consequently increase LV wall stress, leading to elevated plasma natriuretic peptide level or directly promotes the release of natriuretic peptide independent from left ventricular wall stress [5, 6]. Recently, it was discovered that natriuretic peptides are associated with exercise-induced myocardial ischemia in patients with coronary artery disease and BNP level at rest can significantly improve diagnostic power of treadmill test in patients with suspected coronary artery disease and normal left ventricular ejection fraction [7–11]. Stress myocardial perfusion imaging is also widely used noninvasive modality for the diagnosis and risk stratification of patients with suspected myocardial ischemia [12, 13]. The incidence of myocardial perfusion abnormalities at rest or during stress is a hallmark of coronary artery disease [14]. The sensitivity of stress technetium-99m
Calculation of DOS-Dependent Channel Potentials in FETs in the Saturation Condition
Woo-young So,David V. Lang,Arthur P. Ramirez
Physics , 2007,
Abstract: We calculated functions for the potential, Vch, in the channel of a field effect transistor with various densities of the localized states (DOS) by using a device simulator. In the saturation condition, Vch is found to fit satisfactorily to the analytical function, Vch(y)=Vg(1-(1-y/L) k), where Vg is the gate bias, y is the position along the channel, and L is the channel length. The power k, which depends on the DOS, ranges from 0 to 0.5 even with an extensive variation of DOS. As a result, the total induced charge density in the saturation condition can be expressed a way similar to the linear condition by introducing a correction factor, alpha, ranging between 0.65 and 1.0.
Effects of Spiral Arms on Star Formation in Nuclear Rings of Barred-spiral Galaxies
Woo-Young Seo,Woong-Tae Kim
Physics , 2014, DOI: 10.1088/0004-637X/792/1/47
Abstract: We use hydrodynamic simulations to study the effect of spiral arms on the star formation rate (SFR) occurring in nuclear rings of barred-spiral galaxies. We find that spiral arms can be an efficient means of gas transport from the outskirts to the central parts, provided that the arms are rotating slower than the bar. While the ring star formation in models with no-arm or corotating arms is active only during about the bar growth phase, arm-driven gas accretion makes the ring star formation both enhanced and prolonged significantly in models with slow-rotating arms. The arm-enhanced SFR is larger by a factor of ~ 3-20 than in the no-arm model, with larger values corresponding to stronger and slower arms. Arm-induced mass inflows also make dust lanes stronger. Nuclear rings in slow-arm models are ~ 45% larger than in the no-arm counterparts. Star clusters that form in a nuclear ring exhibit an age gradient in the azimuthal direction only when the SFR is small, whereas no noticeable age gradient is found in the radial direction for models with arm-induced star formation.
Gaseous Structures in Barred Galaxies: Effects of the Bar Strength
Woong-Tae Kim,Woo-Young Seo,Yonghwi Kim
Physics , 2012, DOI: 10.1088/0004-637X/758/1/14
Abstract: Using hydrodynamic simulations, we investigate the physical properties of gaseous substructures in barred galaxies and their relationships with the bar strength. The gaseous medium is assumed to be isothermal and unmagnetized. The bar potential is modeled as a Ferrers prolate with index n. To explore situations with differing bar strength, we vary the bar mass fbar relative to the spheroidal component as well as its aspect ratio. We derive expressions as functions of fbar and the aspect ratio for the bar strength Qb and the radius r(Qb) where the maximum bar torque occurs. When applied to observations, these expressions suggest that bars in real galaxies are most likely to have fbar=0.25-0.5 and n<1. Dust lanes approximately follow one of x1-orbits and tend to be more straight under a stronger and more elongated bar, but are insensitive to the presence of self-gravity. A nuclear ring of a conventional x2 type forms only when the bar is not so massive or elongated. The radius of an x2-type ring is generally smaller than the inner Lindblad resonance, decreases systematically with increasing Qb, and slightly larger when self-gravity is included. This evidences that the ring position is not determined by the resonance but by the amount of angular momentum loss at dust-lane shocks. Nuclear spirals exist only when the ring is of the x2-type and sufficiently large in size. Unlike the other features, nuclear spirals are transient in that they start out as being tightly-wound and weak, and then due to the nonlinear effect unwind and become stronger until turning into shocks, with an unwinding rate higher for larger Qb. The mass inflow rate to the galaxy center is found to be less than 0.01 Msun/yr for models with Qb<0.2, while becoming larger than 0.1 Msun/yr when Qb>0.2 and self-gravity is included.
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