Kangwon National University

About: Kangwon National University is a education organization based out in Chuncheon, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 9836 authors who have published 20002 publications receiving 393562 citations. The organization is also known as: KNU.

Purification and characterization of laccase from the white rot fungus Trametes versicolor.

Abstract: Laccase is one of the ligninolytic enzymes of white rot fungus Trametes versicolor 951022, a strain first isolated in Korea. This laccase was purified 209-fold from culture fluid with a yield of 6.2% using ethanol precipitation, DEAE-Sepharose, Phenyl-Sepharose, and Sephadex G-100 chromatography. T. versicolor 951022 excretes a single monomeric laccase showing a high specific activity of 91,443 U/mg for 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) as a substrate. The enzyme has a molecular mass of approximately 97 kDa as determined by SDS-PAGE, which is larger than those of other laccases reported. It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 3.0 and a temperature of 50 degrees C. The Km value of the enzyme for substrate ABTS is 12.8 micrometer and its corresponding Vmax value is 8125.4 U/mg. The specific activity and substrate affinity of this laccase are higher than those of other white rot fungi, therefore, it may be potentially useful for industrial purposes.

A highly durable carbon-nanofiber-supported Pt–C core–shell cathode catalyst for ultra-low Pt loading proton exchange membrane fuel cells: facile carbon encapsulation

Abstract: The carbon encapsulation of nanosized Pt cathode catalysts for ultra-low Pt loading proton exchange membrane fuel cells is an effective approach to enhance their stability and catalytic activity for the oxygen reduction reaction (ORR). However, the synthesis procedures for such a catalyst are delicate and cumbersome. Therefore, it is difficult to use such procedures for mass production. Here, we have developed a facile strategy for synthesizing carbon-encapsulated Pt nanoparticles supported on carbon nanofibers (CNFs) using a Pt–aniline complex. This strategy begins with applying a wet Pt–aniline complex coating to CNFs. Heat-treating the coated CNFs produced 3–4 nm-sized Pt nanoparticles that were uniformly coated with a layer of carbon on the CNF surface (Pt@CS/CNF). Compared to other carbon-coated Pt catalysts, the stability and catalytic activity of Pt@CS/CNF for the ORR are high owing to the robustness of the carbon shells that secure the Pt nanoparticles. In a unit cell test, the performance of Pt@CS/CNF heat-treated at 900 °C was almost maintained for 30 000 accelerated stability test cycles, showing a negligible voltage loss at an operating current density of 0.8 A cm−2.

Revision and update on clinical practice guideline for liver cirrhosis.

Abstract: Liver cirrhosis (LC) is a disease with a high rate of prevalence and one of the most common causes of mortality in the Republic of Korea (hereafter "Korea"). In Korea, the main etiologies of LC have been found to be chronic hepatitis B (CHB), alcohol, and chronic hepatitis C (CHC). In patients with complications such as ascites, variceal bleeding, and encephalopathy, the 5-year survival rates were 32%, 21%, and 40%, respectively, reflecting the poor prognosis of patients with LC. Consequently, a clinical practice guideline appropriate for the medical milieu of Korea is important for both patients and clinicians. In 2005, the Korean Association for the Study of the Liver established a guideline for the treatment of LC that is now widely used. However, it is currently necessary to revise and update the clinical practice guideline based on new evidence over the past 6 years regarding the diagnosis, treatment, and prevention of LC. Therefore, the Korean Association for the Study of the Liver undertook a revision and update of the clinical practice guideline co-organized by the Liver Cirrhosis Clinical Research Center. This guideline was based on an interdisciplinary (hepatology, radiology, pathology, and preventive medicine) approach. A panel of experts selected by the Korean Association for the Study of the Liver and Liver Cirrhosis Clinical Research Center met several times to discuss and write this guideline during 2005-2011. This guideline was written in light of published studies retrieved from MEDLINE, EMBASE, and Cochrane Library. The panel aimed to address 5 subjects: diagnosis of LC, anti-fibrotic therapy for LC, variceal bleeding, ascites, and hepatic encephalopathy. The evidence and recommendations made in this guideline have been graded according to the GRADE (Grading of Recommendations Assessment Development and Evaluation) system. The strength of evidence has been classified into 3 levels: A (high-quality evidence), B (moderate-quality evidence), and C (low-quality evidence). The strength of recommendation has been classified into 2 categories: strong and weak (Table 1). Where there was no clear evidence, the recommendations were based on the consensus expert opinion(s) in literature and that of the writing committee. Table 1 Grading evidence and recommendations 1. Diagnosis of LC LC is a pathologically defined disease, and is clinically classified as compensated and decompensated LC. Decompensated LC includes cases with ascites, variceal bleeding, hepatic encephalopathy, or jaundice. Image studies for diagnosing LC are CT, abdominal ultrasound, and MRI. Typical findings of these images are nodular liver surface, splenomegaly, and the presence of intra-abdominal collateral vessels, which mean increasing portal venous pressure. Although there are not established criteria for the diagnosis of compensated LC, imaging studies may be helpful for the diagnosis of LC b y integrating laboratory findings such as albumin, bilirubin, or prothrombin time and platelet values. 1-1. Diagnostic approach-patient history, physical examination, and laboratory tests When dealing with patients with LC, evaluation of the cause, severity, and stage is the first step. In patients with chronic liver disease, history taking (drug use, blood transfusion, or alcohol use), physical examination (jaundice, ascites, spider angioma, hepatomegaly, or splenomegaly), and symptom such as fatigue from hepatitis should be assessed. In patients with LC, a whole blood test including platelet count, liver function test (albumin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and gamma glutamyl transpeptidase), prothrombin time, abdominal ultrasound, abdominal CT, and endoscopy should be carried out to confirm the presence or absence of cirrhosis. In addition, laboratory tests for hepatitis B or C virus infection are needed for the evaluation of its cause. Generally, the Child-Pugh score is used to assess the severity of LC. In clinical practice for the diagnosis of LC, findings of portal hypertension such as ascites, hepatic encephalopathy, or varices, imaging findings, and laboratory findings are common diagnostic tools. Recently, it was found that nodularity of the liver surface, a platelet count of less than 100,000/mm3, albumin less than 3.5 g/dL, and an international normalized ratio of 1.3 or more are related to the presence of LC. Presence of one condition of these findings showed a specificity of 90.42% and a sensitivity of 61.11%.1

A novel echo-hiding scheme with backward and forward kernels

Abstract: The paper presents a novel echo-hiding method for audio watermarking. The method is quite different from previous echo-hiding methods since it presents a new echo kernel which introduces a forward kernel as well as a backward kernel. The new kernel, a combination of the backward and forward kernels, can enhance considerably the watermark detection rate. Thus, it is possible to reduce echo amplitude. The paper proves mathematically that the combination of kernels improves watermark performance. Experimental results show that the proposed watermarking scheme is much better than previous echo-hiding schemes in terms of detection rate and imperceptibility.

Ischemia-induced changes in glucagon-like peptide-1 receptor and neuroprotective effect of its agonist, exendin-4, in experimental transient cerebral ischemia.

Abstract: Glucagon-like peptide-1 receptor (GLP-1R) protects against neuronal damages in the brain. In the present study, ischemia-induced changes in GLP-1R immunoreactivity in the gerbil hippocampal CA1 region were evaluated after transient cerebral ischemia; in addition, the neuroprotective effect of the GLP-1R agonist exendin-4 (EX-4) against ischemic damage was studied. GLP-1R immunoreactivity and its protein levels in the ischemic CA1 region were highest at 1 day after ischemia/reperfusion (I/R). At 4 days after I/R, GLP-1R immunoreactivity was hardly detected in CA1 pyramidal neurons, and its protein level was lowest. GLP-1R protein level was increased again at 10 days after I/R, and GLP-1R immunoreactivity was found in astrocytes and GABAergic interneurons. In addition, EX-4 treatment attenuated ischemia-induced hyperactivity, neuronal damage, and microglial activation in the ischemic CA1 region in a dose-dependent manner. EX-4 treatment also induced the elevation of GLP-1R immunoreactivity and protein levels in the ischemic CA1 region. These results indicate that GLP-1R is altered in the ischemic region after an ischemic insult and that EX-4 protects against ischemia-induced neuronal death possibly by increasing GLP-1R expression and attenuating microglial activation against transient cerebral ischemic damage.