Jae-Hwan Lee

Impact of Intravascular Ultrasound Guidance on Long-Term Mortality in Stenting for Unprotected Left Main Coronary Artery Stenosis

Background—Although intravascular ultrasound (IVUS) guidance has been useful in stenting for unprotected left main coronary artery stenosis, its impact on long-term mortality is still unclear. Methods and Results—In the MAIN-COMPARE registry, patients with unprotected left main coronary artery stenosis in a hemodynamically stable condition underwent elective stenting under the guidance of IVUS (756 patients) or conventional angiography (219 patients). Patients with acute myocardial infarction were excluded. The 3-year outcomes between the 2 groups were primarily compared using propensity-score matching in the entire and separate populations according to stent type. In 201 matched pairs of the overall population, there was a tendency of lower risk of 3-year morality with IVUS guidance compared with angiography guidance (6.0% versus 13.6%, log-rank P=0.063; hazard ratio, 0.54; 95% CI, 0.28 to 1.03; Cox-model P=0.061). In particular, in 145 matched pairs of patients receiving drug-eluting stent, the 3-year incidence of mortality was lower with IVUS guidance as compared with angiography guidance (4.7% versus 16.0%, log-rank P=0.048; hazard ratio, 0.39; 95% CI, 0.15 to 1.02; Cox model P=0.055). In contrast, the use of IVUS guidance did not reduce the risk of mortality in 47 matched pairs of patients receiving bare-metal stent (8.6% versus 10.8%, log-rank P=0.35; hazard ratio, 0.59; 95% CI, 0.18 to 1.91; Cox model P=0.38). The risk of myocardial infarction or target vessel revascularization was not associated with the use of IVUS guidance. Conclusions—Elective stenting with IVUS guidance, especially in the placement of drug-eluting stent, may reduce the long-term mortality rate for unprotected left main coronary artery stenosis when compared with conventional angiography guidance.

Sirolimus-eluting stent versus paclitaxel-eluting stent for patients with long coronary artery disease.

Background— Outcomes remain relatively unfavorable for stent-based coronary intervention of lesions with long diseased segments. This study compared sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) for long coronary lesions. Methods and Results— The present randomized, multicenter, prospective study compared the use of long (≥32 mm) SES with PES in 500 patients with long (≥25 mm) native coronary lesions. The primary end point of the trial was the rate of binary in-segment restenosis according to follow-up angiography at 6 months. The SES and PES groups had similar baseline characteristics. Lesion length was 33.9±11.6 mm in the SES group and 34.5±12.6 mm in the PES group (P=0.527). The in-segment binary restenosis rate was significantly lower in the SES group than in the PES group (3.3% versus 14.6%; relative risk 0.23; P<0.001). In-stent late loss of lumen diameter was 0.09±0.37 mm in the SES group and 0.45±0.55 mm in the PES group (P<0.001). In patients with restenoses, a pattern of focal restenosis was more common in the SES group than in the PES group (100% versus 53.3%, P=0.031). Consequently, SES patients had a lower rate of target-lesion revascularization at 9 months (2.4% versus 7.2%, P=0.012). The incidence of death (0.8% in SES versus 0% in PES, P=0.499) or myocardial infarction (8.8% in SES versus 10.8% in PES, P=0.452) at 9 months of follow-up was not statistically different between the 2 groups. Conclusions— For patients with long native coronary artery disease, SES implantation was associated with a reduced incidence of angiographic restenosis and a reduced need for target-lesion revascularization compared with PES implantation.

A randomized comparison of sirolimus- versus paclitaxel-eluting stent implantation in patients with diabetes mellitus 2-year clinical outcomes of the DES-DIABETES trial.

To the Editor: The presence of diabetes mellitus has been associated with an increased risk of restenosis and unfavorable clinical outcomes in the era of bare-metal stents (BMS) or drug-eluting stents (DES). Previous studies found sirolimus-eluting stents (SES) to have greater efficacy than

Exact partition function zeros and the collapse transition of a two-dimensional lattice polymer

We study the collapse transition of the lattice homopolymer on a square lattice by calculating the exact partition function zeros. The exact partition function is obtained by enumerating the number of possible conformations for each energy value, and the exact distributions of the partition function zeros are found in the complex temperature plane by solving a polynomial equation. We observe that the locus of zeros closes in on the positive real axis as the chain length increases, providing the evidence for the onset of the collapse transition. By analyzing the scaling behavior of the first zero with the polymer length, we estimate the transition temperature T(θ) and the crossover exponent φ.

Endothelial progenitor cell transplantation decreases lymphangiogenesis and adverse myocardial remodeling in a mouse model of acute myocardial infarction

Cardiac lymphatic system in the remodeling after acute myocardial infarction (AMI) has been overlooked. We wanted to investigate the role of bone marrow-derived endothelial progenitor cells (EPCs) and their contribution to lymphatic distribution in myocardial remodeling after AMI. Mouse (C57bl/6J) MI models were created by ligation of the left anterior descending coronary artery and were treated with phosphate buffered saline (PBS) or EPCs. Real-time RT-PCR with 2- to 4-week myocardial tissue samples revealed that lymphangiogenetic factors such as vascular endothelial growth factor (VEGF)-C (8.5 fold, P < 0.05), VEGF-D (6.1 fold, P < 0.05), Lyve-1 (15 fold, P < 0.05), and Prox-1 (11 fold, P < 0.05) were expressed at significantly higher levels in the PBS group than the EPC group. The PBS group also showed a significantly higher density of lymphatic vessels in the peri-infarction area. Echocardiography showed that from 2 weeks after the treatment, left ventricle (LV) dimensions at both systole and diastole were significantly smaller in the EPC group than in the PBS group (P < 0.01) and LV fractional shortening was higher in the EPC group accordingly (P < 0.01). Lymphangiogenic markers increased in a mouse MI model. EPC transplantation decreased lymphangiogenesis and adverse ventricular remodeling after AMI. These novel findings suggest that new lymphatic vessels may be formed in severely damaged myocardium, and may be involved in adverse myocardial remodeling after AMI.

Parallel algorithm for calculation of the exact partition function of a lattice polymer

We develop a parallel algorithm that calculates the exact partition function of a lattice polymer, by enumerating the number of conformations for each energy level. An efficient parallelization of the calculation is achieved by classifying the conformations according to the shape of the box spanned by a conformation, and enumerating only those in a given box at a time. The calculation time for each box is reduced by preventing the conformations related by symmetries from being generated more than once. The algorithm is applied to study the collapse transition of a lattice homopolymer on a square lattice, by calculating the specific heat for chain lengths up to 36.

Collapse transition of a square-lattice polymer with next nearest-neighbor interaction

We study the collapse transition of a polymer on a square lattice with both nearest-neighbor and next nearest-neighbor interactions, by calculating the exact partition function zeros up to chain length 36. The transition behavior is much more pronounced than that of the model with nearest-neighbor interactions only. The crossover exponent and the transition temperature are estimated from the scaling behavior of the first zeros with increasing chain length. The results suggest that the model is of the same universality class as the usual θ point described by the model with only nearest-neighbor interaction.

Exact partition function zeros of a polymer on a simple cubic lattice.

We study conformational transitions of a polymer on a simple-cubic lattice by calculating the zeros of the exact partition function, up to chain length 24. In the complex temperature plane, two loci of the partition function zeros are found for longer chains, suggesting the existence of both the coil-globule collapse transition and the melting-freezing transition. The locus corresponding to coil-globule transition clearly approaches the real axis as the chain length increases, and the transition temperature could be estimated by finite-size scaling. The form of the logarithmic correction to the scaling of the partition function zeros could also be obtained. The other locus does not show clear scaling behavior, but a supplementary analysis of the specific heat reveals a first-order-like pseudotransition.

Korean Red Ginseng Extract inhibits Tumor Necrosis Factor-alpha-induced Monocyte Adhesion in the Human Endothelial Cells

Vascular inflammation is an important step in the development of cardiovascular disorder. Since it has not been known whether Korean red ginseng has a role to play on the vascular inflammation, we investigated the effects of Korean red ginseng extract (KRGE) on monocyte adhesion and its underlying signaling mechanism. Monocyte adhesion assay and Western blot were conducted on the human umbilical vein endothelial cells to study monocyte adhesion and the expression of adhesion molecules. Intracellular calcium was measured with Fura-2 fluorescent staining, and superoxide production was measured with lucigenin chemiluminescence in the endothelial cells. KRGE inhibits tumor necrosis factor (TNF)-alpha-induced monocyte adhesion on the endothelial cells at the range of 0.03~1 ㎎/㎖. TNF-alpha-induced vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1 expression were inhibited by the pretreatment of KRGE in the endothelial cells. KRGE also inhibits TNF-alpha-induced intracellular calcium and the superoxide production in the endothelial cells. This study first demonstrated that KRGE inhibits TNF-alpha-induced monocyte adhesion by inhibiting the adhesion molecule expression, intracellular calcium and superoxide production in the endothelial cells. Therefore, the anti-inflammatory function of KRGE may be contributed to protecting the endothelial dysfunction in the vascular inflammatory disorders.

Study of a square-lattice Ising superantiferromagnet using the Wang–Landau algorithm and partition function zeros

We study the square-lattice Ising model with nearest-neighbor (J1) and next nearest-neighbor (J2) interactions, using the Wang?Landau Monte Carlo algorithm and the partition function zeros in the complex temperature plane (Fisher zeros). Here, the competition between J1 and J2 interactions is defined by the coupling ratio R = J2/J1. For J2 > 0, the critical behavior is trivial and is the same as the square-lattice Ising model with only J1 interaction. On the other hand, the new phase of superantiferromagnet appears for J2 < 0. However, the nature of the transition into the superantiferromagnetic phase is still controversial in the literature. To resolve the controversy, we estimate the critical temperature Tc(R) and thermal scaling exponent yt(R) from the Fisher zeros, as a function of R. The estimated values of Tc(R) agree well with the results in the literature. We obtain the simple critical behavior with a fixed value of the thermal scaling exponent, yt(R) = 1, for and J2 < 0 (Ising antiferromagnet). For and J2 < 0 (Ising superantiferromagnet), however, it is shown that yt(R) continuously varies depending on R values, and the estimated values of yt(R) are clearly less than that of the first-order phase transition, yt = 2.