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- 저자 : ( C. K. Lim ) (검색결과 1,666 건)
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Kim, C.J.,Kim, Y.J.,Lim, C.Y.,Jun, B.H.,Park, S.D.,Choo, K.N. The Korea Institute of Applied Superconductivity a 2014 한국초전도저온공학회논문지 Vol.16 No.2
Temperature dependence of magnetic moment (m-T) and the magnetization (M-H) at 5 K and 20 K of the in situ processed $MgB_2$ bulk pellets with/without carbon (C) doping were examined. The superconducting critical temperature ($T_c$), the superconducting transition width (${\delta}T$) and the critical current density ($J_c$) were estimated for ten test samples taken from the $MgB_2$ bulk pellets. The reliable m-T characteristics associated with the uniform $MgB_2$ formation were obtained for both $MgB_2$ pellets. The $T_cs$ and ${\delta}Ts$ of all test samples of the undoped $MgB_2$ were the same each other as 37.5 K and 1.5 K, respectively. The $T_cs$ and ${\delta}Ts$ of the C-doped $MgB_2$ were 36.5 K and 2.5 K, respectively. Unlike the m-T characteristics, there existed the difference among the M-H curves of the test samples, which might be caused by the microstructure variation. In spite of the slight $T_c$ decrease, the C doping was effective in enhancing the $J_c$ at 5 K.
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Lim, Y.-R.,Yoon, R.-Y.,Seo, E.-S.,Kim, Y.-S.,Park, C.-S.,Oh, D.-K. Blackwell Publishing Ltd 2010 Journal of Applied Microbiology Vol.109 No.4
<P>Abstract</P><P>Aims: </P><P>To characterize of a thermostable recombinant &agr;-<SMALL>L</SMALL>-arabinofuranosidase from <I>Caldicellulosiruptor saccharolyticus</I> for the hydrolysis of arabino-oligosaccharides to <SMALL>L</SMALL>-arabinose.</P><P>Methods and Results: </P><P>A recombinant &agr;-<SMALL>L</SMALL>-arabinofuranosidase from <I>C. saccharolyticus</I> was purified by heat treatment and Hi-Trap anion exchange chromatography with a specific activity of 28·2 U mg<SUP>−1</SUP>. The native enzyme was a 58-kDa octamer with a molecular mass of 460 kDa, as measured by gel filtration. The catalytic residues and consensus sequences of the glycoside hydrolase 51 family of &agr;-<SMALL>L</SMALL>-arabinofuranosidases were completely conserved in &agr;-<SMALL>L</SMALL>-arabinofuranosidase from <I>C. saccharolyticus</I>. The maximum enzyme activity was observed at pH 5·5 and 80°C with a half-life of 49 h at 75°C. Among aryl-glycoside substrates, the enzyme displayed activity only for <I>p</I>-nitrophenyl-&agr;-<SMALL>L</SMALL>-arabinofuranoside [maximum <I>k</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB> of 220 m(mol l<SUP>−1</SUP>)<SUP>−1</SUP> s<SUP>−1</SUP>] and <I>p</I>-nitrophenyl-&agr;-<SMALL>L</SMALL>-arabinopyranoside. This substrate specificity differs from those of other &agr;-<SMALL>L</SMALL>-arabinofuranosidases. In a 1 mmol l<SUP>−1</SUP> solution of each sugar, arabino-oligosaccharides with 2–5 monomer units were completely hydrolysed to <SMALL>L</SMALL>-arabinose within 13 h in the presence of 30 U ml<SUP>−1</SUP> of enzyme at 75°C.</P><P>Conclusions: </P><P>The novel substrate specificity and hydrolytic properties for arabino-oligosaccharides of &agr;-<SMALL>L</SMALL>-arabinofuranosidase from <I>C. saccharolyticus</I> demonstrate the potential in the commercial production of <SMALL>L</SMALL>-arabinose in concert with endoarabinanase and/or xylanase.</P><P>Significance and Impact of the Study: </P><P>The findings of this work contribute to the knowledge of hydrolytic properties for arabino-oligosaccharides performed by thermostable &agr;-<SMALL>L</SMALL>-arabinofuranosidase.</P>
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Kim, H.,Hwang, J.,Park, S.,Nahm, S.F.,Min, S.,Lim, C.,Park, K.,Han, S. C.V. Mosby Co 2014 Journal of Vascular Surgery Vol.59 No.4
Objective: Neuroprotective effects of the peroxisome proliferator-activated receptor gamma (PPARγ) agonist in cerebral ischemia have been reported, but the effect of a PPARγ agonist on spinal cord ischemia has not been investigated. The objective of this study was to investigate the effect of a PPARγ agonist on spinal cord ischemia. Pioglitazone, a PPARγ agonist, was administered in a rat model of spinal cord ischemia, and the extent of neurological damage and histological alterations were assessed. Methods: Forty-five rats were randomly enrolled into one of the three groups: (1) pioglitazone group (group PIO): rats were treated with pioglitazone 24 hours before ischemia; (2) control group (group C): rats were treated with the same volume of saline 24 hours before ischemia; and (3) sham group (group sham): rats were treated with the same volume of saline 24 hours before the sham surgery. Spinal cord ischemia was induced using a balloon-tipped catheter placed on the proximal descending aorta. Neurologic function was assessed using the motor deficit index (0 = normal, 6 = complete paralysis) during the 48 hours after reperfusion. Histological and biochemical evaluations were then performed. Results: Compared with group C, group PIO presented with lower motor deficit index 48 hours after reperfusion (5.0 [4.0-6.0] vs 3.0 [2.0-3.0]; group C vs group PIO, respectively; P < .001). Group PIO presented with a higher number of normal motor neurons (10.7 [8.1-11.9] vs 14.7 [14.0-15.3]; group C vs group PIO, respectively; P = .009) and a smaller area of infarcts (48.4% [46.3%-54.0%] vs 16.8% [11.5%-18.3%]; group C vs group PIO, respectively; P = .009) when compared with group C. The degree of inflammatory reactions, assessed by microglia activities, was significantly reduced in group PIO. Oxidative stress level, assessed using malonydialdehyde assay, was significantly reduced in group PIO relative to group C (192.21% [173.5%-206.4%] of sham vs 141.1% [131.7%-152.1%] of sham; group C vs group PIO, respectively; P = .007). The sham group exhibited no abnormality upon neurological or histological examination. Conclusions: PPARγ agonist pioglitazone pretreatment significantly reduces infarct volume and attenuates neurological deficits following spinal cord ischemia. The possible mechanism of neuroprotection by PPARγ agonist may involve modulation of inflammatory reaction and oxidative stress.
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Jo, M.J.,Paek, A.R.,Choi, J.S.,Ok, C.Y.,Jeong, K.C.,Lim, J.H.,Kim, S.H.,You, H.J. North-Holland ; Elsevier Science Ltd 2015 european journal of pharmacology Vol.769 No.-
<P>The proto-oncogene c-Myc has been implicated in a variety of cellular processes, such as proliferation, differentiation and apoptosis. Several c-Myc targets have been studied; however, selective regulation of c-Myc is not easy in cancer cells. Herein, we attempt to identify chemical compounds that induce cell death in c-Myc-overexpressing cells (STF-cMyc and STF-Control) by conducting MTS assays on approximately 4000 chemical compounds. One compound, C604, induced cell death in STF-cMyc cells but not STF-Control cells. Apoptotic proteins, including caspase-3 and poly(ADP-ribose) polymerase (PAPP), were cleaved in C604-treated STF-cMyc cells. In addition, 5W620, HCT116 and NCI-H23 cells, which exhibit higher basal levels of c-Myc, underwent apoptotic cell death in response to C604, suggesting a role for C604 as an inducer of apoptosis in cancer cells with c-Myc amplification. C604 induced cell cycle arrest at the G2/M phase in cells, which was not affected by apoptotic inhibitors. Interestingly, C604 induced accumulation of c-Myc and Cdc25A proteins. In summary, a chemical compound was identified that may induce cell death in cancer cells with c-Myc amplification specifically through an apoptotic pathway. (C) 2015 Elsevier B.V. All rights reserved.</P>
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Hwang, S.M.,Sung, K.,Choi, J.H.,Kim, W.,Joo, J.,Lim, J.H.,Kim, C.J.,Park, Y.S.,Kim, D.H. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.20
We selected polyacrylonitrile (PAN, -[C<SUB>3</SUB>H<SUB>3</SUB>N]-) as an O-free organic dopant and fabricated C-doped MgB<SUB>2</SUB> wires by in situ and powder-in-tube techniques. 0-5 wt.% PAN powders were uniformly mixed with B powder using a liquid mixing method. The precursor powders were mixed with Mg powder, filled into Fe tubes, and then drawn into wires. Sintering was performed at 900<SUP>o</SUP>C for 1h in a flowing Ar gas. The PAN doping decreased the critical temperature (T<SUB>c</SUB>) and a-axis lattice parameter, but significantly improved the critical current density (J<SUB>c</SUB>) in high fields, upper critical field (H<SUB>c2</SUB>), and irreversibility field (H<SUB>irr</SUB>) performances. These results are attributed to the replacement of B sites with C by the PAN doping. Furthermore, as expected, the MgO amount did not increase as the doping content increased. The J<SUB>c</SUB> of the PAN-doped MgB<SUB>2</SUB> wires was more than one order of magnitude higher than that of the undoped MgB<SUB>2</SUB> wire at 5K and 6.6T (1.46-3.82kA/cm<SUP>2</SUP> vs. 0.11kA/cm<SUP>2</SUP>).
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Novel signaling axis for ROS generation during K-Ras-induced cellular transformation
Park, M-T,Kim, M-J,Suh, Y,Kim, R-K,Kim, H,Lim, E-J,Yoo, K-C,Lee, G-H,Kim, Y-H,Hwang, S-G,Yi, J-M,Lee, S-J Macmillan Publishers Limited 2014 CELL DEATH AND DIFFERENTIATION Vol.21 No.8
Reactive oxygen species (ROS) are well known to be involved in oncogene-mediated cellular transformation. However, the regulatory mechanisms underlying ROS generation in oncogene-transformed cells are unclear. In the present study, we found that oncogenic K-Ras induces ROS generation through activation of NADPH oxidase 1 (NOX1), which is a critical regulator for the K-Ras-induced cellular transformation. NOX1 was activated by K-Ras-dependent translocation of p47<SUP>phox</SUP>, a subunit of NOX1 to plasma membrane. Of note, PKCδ, when it was activated by PDPK1, directly bound to the SH3-N domain of p47<SUP>phox</SUP> and catalyzed the phosphorylation on Ser348 and Ser473 residues of p47<SUP>phox</SUP> C-terminal in a K-Ras-dependent manner, finally leading to its membrane translocation. Notably, oncogenic K-Ras activated all MAPKs (JNK, ERK and p38); however, only p38 was involved in p47<SUP>phox</SUP>-NOX1-dependent ROS generation and consequent transformation. Importantly, K-Ras-induced activation of p38 led to an activation of PDPK1, which then signals through PKCδ, p47<SUP>phox</SUP> and NOX1. In agreement with the mechanism, inhibition of p38, PDPK1, PKCδ, p47<SUP>phox</SUP> or NOX1 effectively blocked K-Ras-induced ROS generation, anchorage-independent colony formation and tumor formation. Taken together, our findings demonstrated that oncogenic K-Ras activates the signaling cascade p38/PDPK1/PKCδ/p47<SUP>phox</SUP>/NOX1 for ROS generation and consequent malignant cellular transformation.
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Kim, T.H.,Jo, Y.G.,Jiang, H.H.,Lim, S.M.,Youn, Y.S.,Lee, S.,Chen, X.,Byun, Y.,Lee, K.C. Elsevier Science Publishers 2012 Journal of controlled release Vol.162 No.2
Transferrin (Tf) is considered an effective tumor-targeting agent, and PEGylation effectively prolongs in vivo pharmacokinetics by delaying excretion via the renal route. The authors describe the active tumor targeting of long-acting Tf-PEG-TNF-related apoptosis-inducing ligand conjugate (Tf-PEG-TRAIL) for effective cancer therapy. Tf-PEG-TRAIL was prepared using a two-step N-terminal specific PEGylation procedure using different PEGs (Mw: 3.4, 5, 10kDa). Eventually, only 10kDa PEG was linked to Tf and TRAIL because TRAIL (66kDa) and Tf (81kDa) were too large to link to 3.4 and 5kDa PEG. The final conjugate Tf-PEG<SUB>10K</SUB>-TRAIL was successfully purified and characterized by SDS-PAGE, western blotting. To determine the specific binding of Tf-PEG<SUB>10K</SUB>-TRAIL to Tf receptor, competitive receptor binding assays were performed on K 562 cells. The results obtained demonstrate that the affinity of Tf-PEG<SUB>10K</SUB>-TRAIL for Tf receptor is similar to that of native Tf. In contrast, PEG<SUB>10K</SUB>-TRAIL demonstrated no specificity. Biodistribution patterns and antitumor effects were investigated in C57BL6 mice bearing B16F10 murine melanomas and BALB/c athymic mice bearing HCT116. Tumor accumulation of Tf-PEG<SUB>10K</SUB>-TRAIL was 5.2 fold higher (at 2h) than TRAIL, because Tf-PEG<SUB>10K</SUB>-TRAIL has both passive and active tumor targeting ability. Furthermore, the suppression of tumors by Tf-PEG<SUB>10K</SUB>-TRAIL was 3.6 and 1.5 fold those of TRAIL and PEG<SUB>10K</SUB>-TRAIL, respectively. These results suggest that Tf-PEG<SUB>10K</SUB>-TRAIL is a superior pharmacokinetic conjugate that potently targets tumors and that it should be viewed as a potential cancer therapy.
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The Magnetic Properties of Rapidly Quenched Yttrium - Palladium - Borocarbides Ribbon
K. S. Kim,S. C. Yu,Y. M. Moon,J. S. Baek,W. Y. Lim 한국자기학회 1996 Journal of Magnetics Vol.1 No.1
We have studied the superconductivity of rapidly quenched YPd₂B₂C ribbons. The superconductivity in bulk YPd₂B₂C is completely suppressed by annealing as-cast ingots at higher temperatures, suggesting that the superconducting phase is metastable. The rapidly quenched sample, in the as-quenched state, shows the superconducting transition temperature of about 21 K. From our magnetic data, the value for the upper critical field H_(c2) (0) is estimated to be 10 T. The critical current density and the expected specific heat discontinuity (ΔC/γTc) were obtained to be about 10^8 A/㎡ at 10 Oe and 1.55, respectively.
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Lim, I.,Lee, D.Y.,Patil, S.A.,Shrestha, N.K.,Kang, S.H.,Nah, Y.C.,Lee, W.,Han, S.H. Elsevier Science Publishers 2014 Materials chemistry and physics Vol.148 No.3
The compact (c-Cu<SUB>x</SUB>S) and the porous (p-Cu<SUB>x</SUB>S) with particle decorated films of coppers-ulfidearesynthesized using a chemical bath deposition technique, and the films are characterized using electrochemical techniques. In addition, the chemically deposited Cu<SUB>x</SUB>S films are investigated as a counter electrode in quantum dots-sensitized solar cells (QSSCs). The available redox active reaction sites of the p-Cu<SUB>x</SUB>S film are found to be 57.9% higher than those available in the c-Cu<SUB>x</SUB>S film. From the electrochemical impedance spectroscopy, the effective diffusion coefficients of the polysulfide electrolyte in the c-Cu<SUB>x</SUB>S and p-Cu<SUB>x</SUB>S films are estimated to be 3.67 x 10<SUP>-5</SUP> and 6.35 x 10<SUP>-5</SUP> cm<SUP>2</SUP> s<SUP>-1</SUP>, respectively. These results can be ascribed to the improvement in the available redox active reaction sites and the electrocatalytic activity of the Cu<SUB>x</SUB>S counter electrode. As compared to the c-Cu<SUB>x</SUB>S film, the p-Cu<SUB>x</SUB>S film as a counter electrode exhibits an enhanced photovoltaic performance of the QSSCs with the power conversion efficiency of 3.17%, short-circuit current of 11.89 mA c<SUP>-</SUP>m<SUP>2</SUP>, open-circuit voltage of 0.50 V, and fill factor of 53.29. The improved performance of the QSSCs is ascribed to the improvements on the available redox active reaction sites, electrocatalytic activity and the diffusion coefficients, which are directly related to the surface morphology of the sulfide films.
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