Jang Young Kim

Developmental Properties of the Hertwig’s Epithelial Root Sheath in Mice

Hertwig’s epithelial root sheath (HERS) plays an important role in tooth root formation. In this study, we examined root formation of the first molar in mice, focusing on cell proliferation, cell death, cell migration, and the expression patterns of the signaling molecules, including glycoproteins and proteoglycans between PN8 and PN26. The number of HERS cells decreased during root formation, although HERS retained total length until PN15. The migration of HERS cells did not occur during root formation. Moreover, the immunopositive reaction of laminin beta-3 and syndecan-1 in HERS indicates that both cell adhesion and cell proliferation are essential for HERS development. Bmp-2, Bmp-4, and Msx-2 were expressed in HERS cells during root formation. We also developed an in vitro culture system for investigating the periodontium and suggest that this system provides an excellent vehicle for full exploration, and hence improved understanding, of the development and regeneration of the periodontium. Together, our results provide a comprehensive model describing the morphogenesis of early root development in vertebrates.

Guidewire-induced coronary artery perforation treated with transcatheter injection of polyvinyl alcohol form

We describe a first case of successful transcatheter management of guidewire‐induced distal coronary artery perforation and impending cardiac tamponade, which developed during percutaneous coronary angioplasty, with transcatheter injection of polyvinyl alcohol form. This method may be an effective alternative in the management of distal coronary artery perforation requiring surgical repair.

Beneficial effects of candesartan, an angiotensin‐blocking agent, on compensated alcoholic liver fibrosis ‐ A randomized open‐label controlled study

Recent studies have shown that the renin‐angiotensin system is implicated in hepatic fibrogenesis in vitro and in vivo. However, no study was done in humans with alcoholic liver disease.

Measurement of energy budget components during the International Rice Experiment (IREX) in Japan

A field study was conducted to measure the fluxes of energy budget components above a rice canopy in Okayama, Japan, from 5 to 16 August 1996. During this period, the canopy height was, on average, 0.72 m and the leaf area index was about 3.1. The study site was approximately 300 m × 300 m, and was surrounded by similar rice fields. Our footprint analysis indicated that > 90% of the measured flux (at a height of 2.2 m above the ground) was expected from within the nearest 300 m of upwind area. The closure of the energy budget was examined to ensure the data quality. Owing to poor thermal conductivity of the heat transducers, soil heat fluxes were corrected for the difference in the thermal conductivities of the paddy soil and the transducer. Eddy covariance fluxes were corrected for the effects of line averaging and the sensor separation. Latent heat flux was further corrected for the density fluctuations. The magnitudes of the total corrections were not small and amounted to up to 20% of the raw flux values. With these corrections the surface energy budget of a rice stand was closed within 1% under drained conditions and 5% under flooded conditions. The daily evapotranspiration (ET) rate was near the potential rate of open water evaporation and ranged from 4.2 to 5.8 mm d -1 . In terms of changes in crop water use with irrigation, no difference in ET rates was found between the drained and flooded conditions.

Feasibility of the Radial Artery as a Vascular Access Route in Performing Primary Percutaneous Coronary Intervention.

We aimed to evaluate the feasibility of transradial primary percutaneous coronary intervention (PCI) in patients with ST elevation myocardial infarction (STEMI) by comparing the procedural results and complications with those of transfemoral intervention. From April 1997 to October 2004, we enrolled 352 consecutive cases of STEMI who underwent primary PCI. The femoral route was used in 132 cases (TFI group) and the radial route was used in 220 cases (TRI group). Cases with Killips class IV, a negative Allen test or a non-palpable radial artery were excluded from our study. Baseline clinical and angiographic profiles were comparable in both groups. Vascular access time was 3.8 ± 3.5 min in the TFI group and 3.6 ± 3.1 min in the TRI group, and cath room to reperfusion time was 25 ± 11 min in the TRI group and 26 ± 13 min in the TRI group. The procedural success rate was 89% in the TFI group and 88% in the TRI group. Crossover occurred in 9 cases (4%) due to approaching vessel tortuosity in the TRI group. Major access site complications occurred in 7 cases (5%) in the TFI group, and there were no complications in the TRI group (p < 0.001). Although radial occlusion occurred in 5 cases of the TRI group, there was no evidence of hand ischemia. The total hospital stay was significantly shorter in TRI group than in TFI group. In conclusion, use of the radial artery might be a potential vascular access route in performing primary PCI in selected cases.

Clinical characteristics and prognostic factors of stress-induced cardiomyopathy

Background and Objectives Stress-induced cardiomyopathy (SCM) is characterized by a transient left ventricular (LV) dysfunction due to emotional and physical stress. There are limited data about the clinical characteristics in Korean patients. We sought to clarify the clinical features and prognosis in patients with SCM. Subjects and Methods We reviewed 39 cases diagnosed with SCM in a tertiary hospital. The SCM was diagnosed as: 1) no previous history of cardiac disease, 2) acute onset, 3) regional wall motion abnormality, typically in the takotsubo or inverted takotsubo shape by echocardiography, and 4) no significant stenosis in the coronary angiogram. We evaluated clinical characteristics, biomarkers, and prognosis. Results Mean age was 61.3±16.1 years (female 69%). The triggering factors were physical stress in 32 patients (82%) and emotional stress in 5 patients (13%). The initial symptom was dyspnea (n=18, 46%) rather than chest pain (n=10, 26%). An initial electrocardiogram (EKG) presented T-wave inversion (n=18, 46%), ST-elevation (n=11, 28%), and ST-depression (n=2, 5%). Multivariate logistic regression analysis showed that initial high sensitive C-reactive protein (hs-CRP) {odds ratio (OR) 1.41, 95% confidence interval (CI); 1.02-1.97} and initial left ventricular ejection fraction (LVEF) (OR 0.89, 95% CI; 0.80-0.98) were significantly associated with death or cardiogenic shock, respectively. Conclusion The major triggering factor of SCM is physical stress due to illness or surgical procedures, and the first manifestation is dyspnea rather than chest pain. Elevated hs-CRP and decreased LVEF at admission were independent risk factors for death or cardiogenic shock.

Cardiovascular Parameters Correlated with Metabolic Syndrome in a Rural Community Cohort of Korea: The ARIRANG Study

Although metabolic syndrome (MetS) is associated with increased cardiovascular mortality and the development of atherosclerosis, consensus is still lacking on the status of cardiovascular function and geometry in MetS patients. We investigated the relation between MetS and left ventricle (LV) geometry and function, carotid intima-media thickness (IMT) and arterial stiffness in a community-based cohort of 702 adult subjects. Subjects were categorized into three groups according to the number of MetS components present, as defined by the Adult Treatment Panel III guidelines: 1) Absent (0 criteria), 2) Pre-MetS (1-2 criteria) or 3) MetS (≥3 criteria). In female subjects, LV mass, LV mass/height2.7, deceleration time, and aortic pulse wave velocity increased, and E/A ration decreased in a stepwise manner across the three groups. These changes were not observed in male subjects. The mean carotid IMT was higher in the MetS group than in the other two groups. The degree of MetS clustering is found to be strongly correlated with geometric eccentricity of LV hypertrophy, diastolic dysfunction and arterial changes irrespective of age and blood pressure status, particularly in females. Waist circumference is found to have the most powerful effect on cardiovascular parameters.

A cohort study of serum bilirubin levels and incident non-alcoholic fatty liver disease in middle aged Korean workers.

Background Serum bilirubin may have potent antioxidant and cytoprotective effects. Serum bilirubin levels are inversely associated with several cardiovascular and metabolic endpoints, but their association with nonalcoholic fatty liver disease (NAFLD) has not been investigated except for a single cross-sectional study in a pediatric population. We assessed the prospective association between serum bilirubin concentrations (total, direct, and indirect) and the risk for NAFLD. Methods and Findings We performed a cohort study in 5,900 Korean men, 30 to 59 years of age, with no evidence of liver disease and no major risk factors for liver disease at baseline. Study participants were followed in annual or biennial health examinations between 2002 and 2009. The presence of fatty liver was determined at each visit by ultrasonography. We observed 1,938 incident cases of NAFLD during 28,101.8 person-years of follow-up. Increasing levels of serum direct bilirubin were progressively associated with a decreasing incidence of NAFLD. In age-adjusted models, the hazard ratio for NAFLD comparing the highest to the lowest quartile of serum direct bilirubin levels was 0.61 (95% CI 0.54–0.68). The association persisted after adjusting for multiple metabolic parameters (hazard ratio comparing the highest to the lowest quartile 0.86, 95% CI 0.76–0.98; P trend = 0.039). Neither serum total nor indirect bilirubin levels were significantly associated with the incidence of NAFLD. Conclusions In this large prospective study, higher serum direct bilirubin levels were significantly associated with a lower risk of developing NAFLD, even adjusting for a variety of metabolic parameters. Further research is needed to elucidate the mechanisms underlying this association and to establish the role of serum direct bilirubin as a marker for NAFLD risk.

The Significance of Clopidogrel Low-Responsiveness on Stent Thrombosis and Cardiac Death Assessed by the Verifynow P2Y12 Assay in Patients With Acute Coronary Syndrome Within 6 Months After Drug-Eluting Stent Implantation

Background and Objectives Clopidogrel resistance or low-responsiveness may be associated with recurrent atherothrombotic events after drug-eluting stent (DES) implantation. We prospectively evaluated the association between clopidogrel resistance assessed by the Verifynow™ P2Y12 assay (Accumetrics, San Diego, CA, USA) and stent thrombosis (ST) or cardiac death (CD) in patients with acute coronary syndrome (ACS) within 6 months after DES implantation. Subjects and Methods We enrolled 237 consecutive patients (160 males, 65.2±10.3 years) with ACS who received a DES implantation. The composite endpoint was defined to CD or ST by Academic Research Consortium definitions within 6 months post-implantation. Clopidogrel resistance was defined as <20% inhibition of the P2Y12 receptor. Results Baseline demographic characteristics were similar between 142 normal individuals and 95 clopidogrel resistant patients. CD occurred in one case (0.7%) in the normal group and two cases (2.13%) in the resistant group (p=0.344). There was no episode of ST in the normal group and four episodes in the resistant group (4.2%, four definite ST) (p=0.035). Univariate logistic regression revealed an adjusted odds ratio (OR) for composite end point of CD or ST of 9.646 {95% confidence interval (CI) 1.139-81.679}, and multivariate logistic regression for composite end point revealed an OR of 12.074 (95% CI 1.205-120.992). Conclusion Clopidogrel low-responsiveness assessed by the Verifynow™ P2Y12 assay is an independent predictor of ST and composite end point of ST or CD in patients with ACS within 6 months after DES implantation.

Direction of blood flow from the left ventricle during cardiopulmonary resuscitation in humans—its implications for mechanism of blood flow

BACKGROUND Common mechanisms proposed to explain forward blood flow during cardiopulmonary resuscitation (CPR) include the cardiac and thoracic pumps. However, the exact role of the left ventricle in promoting forward blood flow during standard CPR in humans is mostly unknown. The aim of this study was to explore the role of the left ventricle in generating forward blood flow during standard CPR in humans by observing the direction of blood flow during CPR. METHODS Ten patients with non-traumatic cardiac arrest were enrolled in this study. During CPR, contrast echocardiography with agitated saline was performed in the left ventricle and the aorta, and the direction of contrast flow was assessed using transesophageal echocardiography. RESULTS On injecting the contrast in the aortic root, anterograde flow from the aorta during the compression phase was observed. No aortic regurgitation was present. Retrograde blood flow from the left ventricle into the left atrium as well as anterograde blood flow from the left ventricle into the aorta during the compression phase of CPR was observed in all cases. On injecting the contrast in the aortic root, anterograde flow from the aorta during the compression phase was observed. During each cycle of chest compression, the mitral valve closed during compression and opened during relaxation, and the aortic valve opened during compression and closed during relaxation. CONCLUSIONS Retrograde flow to the left atrium and forward blood flow onto the aorta on left ventricular contrast echocardiography during the compression phase suggests that extrinsic compression of the left ventricle by external chest compression acts as a pump in generating blood flow during standard CPR in humans.