Observation of First-Order Metal-Insulator Transition without Structural Phase Transition in VO_2

An abrupt first-order metal-insulator transition (MIT) without structural phase transition is first observed by current-voltage measurements and micro-Raman scattering experiments, when a DC electric field is applied to a Mott insulator VO_2 based two-terminal device. An abrupt current jump is measured at a critical electric field. The Raman-shift frequency and the bandwidth of the most predominant Raman-active A_g mode, excited by the electric field, do not change through the abrupt MIT, while, they, excited by temperature, pronouncedly soften and damp (structural MIT), respectively. This structural MIT is found to occur secondarily.Comment: 4 pages, 4 figure

A Novel Defined TLR3 Agonist as an Effective Vaccine Adjuvant

Synthetic double-stranded RNA analogs recognized by Toll-like receptor 3 (TLR3) are an attractive adjuvant candidate for vaccines, especially against intracellular pathogens or tumors, because of their ability to enhance T cell and antibody responses. Although poly(I:C) is a representative dsRNA with potent adjuvanticity, its clinical application has been limited due to heterogeneous molecular size, inconsistent activity, poor stability, and toxicity. To overcome these limitations, we developed a novel dsRNA-based TLR3 agonist named NexaVant (NVT) by using PCR-coupled bidirectional in vitro transcription. Agarose gel electrophoresis and reverse phase-HPLC analysis demonstrated that NVT is a single 275-kDa homogeneous molecule. NVT appears to be stable since its appearance, concentration, and molecular size were unaffected under 6 months of accelerated storage conditions. Moreover, preclinical evaluation of toxicity under good laboratory practices showed that NVT is a safe substance without any signs of serious toxicity. NVT stimulated TLR3 and increased the expression of viral nucleic acid sensors TLR3, MDA-5, and RIG-1. When intramuscularly injected into C57BL/6 mice, ovalbumin (OVA) plus NVT highly increased the migration of dendritic cells (DCs), macrophages, and neutrophils into inguinal lymph node (iLN) compared with OVA alone. In addition, NVT substantially induced the phenotypic markers of DC maturation and activation including MHC-II, CD40, CD80, and CD86 together with IFN-β production. Furthermore, NVT exhibited an appropriate adjuvanticity because it elevated OVA-specific IgG, in particular, higher levels of IgG2c (Th1-type) but lower IgG1 (Th2-type). Concomitantly, NVT increased the levels of Th1-type T cells such as IFN-γ+CD4+ and IFN-γ+CD8+ cells in response to OVA stimulation. Collectively, we suggest that NVT with appropriate safety and effectiveness is a novel and promising adjuvant for vaccines, especially those requiring T cell mediated immunity such as viral and cancer vaccines

Monoclinic and Correlated Metal Phase in VO_2 as Evidence of the Mott Transition: Coherent Phonon Analysis

In femtosecond pump-probe measurements, the appearance of coherent phonon oscillations at 4.5 THz and 6.0 THz indicating the rutile metal phase of VO_2 does not occur simultaneously with the first-order metal-insulator transition (MIT) near 68^oC. The monoclinic and correlated metal(MCM) phase between the MIT and the structural phase transition (SPT) is generated by a photo-assisted hole excitation which is evidence of the Mott transition. The SPT between the MCM phase and the rutile metal phase occurs due to subsequent Joule heating. The MCM phase can be regarded as an intermediate non-equilibrium state.Comment: 4 pages, 2 figure

Comparison of infarct-related artery vs multivessel revascularization in ST-segment elevation myocardial infarction with multivessel disease: Analysis from Korea Acute Myocardial Infarction Registry

Background: Many ST-segment elevation myocardial infarction (STEMI) patients have multivessel disease. There is still controversy in treatment strategy in STEMI patients with multivessel disease. We compared clinical outcomes of multivessel revascularization with infarct- related artery (IRA) revascularization in STEMI patients. Methods: The 1,644 STEMI patients with multivessel disease (1,106 in IRA group, 538 in multivessel group) who were received primary percutaneous coronary intervention (PCI) were analyzed from a nationwide Korea Acute Myocardial Infarction Registry. Primary endpoint was 12-month major adverse cardiac events (MACE, defined as death, myocardial infarction, and repeated revascularization). Secondary endpoints were 1-month MACE and each component, stent thrombosis during 12 month follow-up, and each components of the 12-month MACE. Results: There were more patients with unfavorable baseline conditions in IRA group. 12-month MACE occurred in 165 (14.9%) patients in IRA group, 81 (15.1%) patients in multivessel group (p = 0.953). There were no statistical significance in the rate of 1-month MACE, each components of 1-month MACE, and stent thrombosis during 12 month follow-up. Each components of 12-month MACE were occurred similarly in both groups except for target lesion revascularization (2.4% in IRA group vs 5.9% in multivessel group, p < 0.0001). After adjusting for confounding factors, multivessel revascularization was not associated with reduced 12-month MACE (OR 1.096, 95% CI 0.676&#8211;1.775, p = 0.711). Conclusions: There were no significant differences in clinical outcomes between both groups except for high risk of target lesion revascularization in multivessel revascularization group

Prognosis according to the timing of percutaneous coronary intervention in non-ST segment elevation myocardial infarction, based on the Korean Acute Myocardial Infarction Registry (KAMIR)

Background: Patients with acute coronary syndrome without ST-segment elevation (ACS- -NSTE) are at risk for adverse cardiac events. Based on data in the Korean Acute Myocardial Infarction Registry (KAMIR), we analyzed the prognosis according to the timing of percutaneous coronary intervention (PCI) in patients with NSTEMI in Korea. Methods and results: 2,455 patients with NSTEMI in KAMIR were classified according to the time interval from the onset of cardiac symptoms to PCI. Patients in Group I underwent PCI within 24 hours of the onset of symptoms; in Group II between 24 and 48 hours; and in Group III after 48 hours. Major adverse cardiac events (MACEs) are defined as cardiac death, non-cardiac death, myocardial infarction, revascularization and coronary-artery bypass graft surgery. The MACEs were compared between groups. Of the 2,455 patients, 743 (30.2%) were assigned to Group I, 583 (23.7%) to Group II, and 1,129 (45.9%) to Group III. The total incidence of MACEs was higher in Group I than Group III, and similar between Groups I and II (Group I: 15.1%, Group II: 14.4%, Group III: 11.6%, p = 0.053). The incidence of MACEs in the intermediate TIMI risk score group had decreased as the intervention time was delayed. Conclusions: The prognosis according to the timing of PCI in patients with NSTEMI was similar based on the data in KAMIR. TIMI risk score was related to a high incidence of MACEs. (Cardiol J 2011; 18, 4: 421&#8211;429