Effects of nano-carbon doping and sintering temperature on microstructure and properties of MgB₂

Lim, J.H.,Shim, J.H.,Choi, J.H.,Park, J.H.,Kim, W.,Joo, J.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

We fabricated nano-carbon (NC) doped MgB<SUB>2</SUB> bulks using an in situ process in order to improve the critical current density (J<SUB>c</SUB>) under a high magnetic field and evaluated the correlated effects of the doped carbon content and sintering temperature on the phase formation, microstructure and critical properties. MgB<SUB>2-x</SUB>C<SUB>x</SUB> bulks with x=0 and 0.05 were fabricated by pressing the powder into pellets and sintering at 800<SUP>o</SUP>C, 900<SUP>o</SUP>C, or 1000<SUP>o</SUP>C for 30min. We observed that NC was an effective dopant for MgB<SUB>2</SUB> and that part of it was incorporated into the MgB<SUB>2</SUB> while the other part remained (undoped), which reduced the grain size. The actual C content was estimated to be 68-90% of the nominal content. The NC doped samples exhibited lower T<SUB>c</SUB> values and better J<SUB>c</SUB>(B) behavior than the undoped samples. The doped sample sintered at 900<SUP>o</SUP>C showed the highest J<SUB>c</SUB> value due to its high doping level, small amount of second phase, and fine grains. On the other hand, the J<SUB>c</SUB> was decreased at a sintering temperature of 1000<SUP>o</SUP>C as a result of the formation of MgB<SUB>4</SUB> phase.

Interleukin-18, transforming growth factor-β, and vascular endothelial growth factor gene polymorphisms and susceptibility to primary glomerulonephritis

Choi, H.-J.,Cho, J.-H.,Kim, J.-C.,Seo, H.-J.,Hyun, S.-H.,Kim, G.-H.,Choi, J.-Y.,Choi, H.-J.,Ryu, H.-M.,Cho, J.-H.,Park, S.-H.,Kim, Y.-L.,Han, S.,Kim, C.-D. Blackwell Publishing Ltd 2010 Tissue antigens Vol.76 No.4

<P>Several studies have showed an association of gene polymorphisms with the development of glomerulonephritis (GN). We investigated the effects of gene polymorphisms on the development of GN by analyzing polymorphisms in the interleukin (IL)-18, transforming growth factor (TGF)-β, and vascular endothelial growth factor (VEGF) genes in Korean patients with primary GN. The study included 146 normal subjects (controls) and 100 patients diagnosed with primary GN by kidney biopsy. The gene polymorphisms A-607C and G-137C in <I>IL-18</I>, C-509T and T869C in <I>TGF-</I>β<I>1</I>, and C-2578A and C405G in <I>VEGF</I> were investigated in DNA extracted from peripheral blood. Significant differences were observed between the GN and control groups in the genotype and allele frequencies of A-607C <I>IL-18</I> and C405G <I>VEGF</I>. The frequencies of the <I>IL-18</I>−607CC genotype [<I>P</I> = 0.001, odds ratio (OR) = 2.473] and the <I>VEGF</I> 405GG genotype (<I>P</I> = 0.001, OR = 2.473) were significantly increased in the GN group. The combination of <I>IL-18</I>−607CC+ and <I>VEGF</I> 405GG+ genotypes had a higher risk for developing GN in comparison with the combination of <I>IL-18</I>−607CC− and <I>VEGF</I> 405GG− genotypes (<I>P</I> < 0.001, OR = 8.642). In the haplotype analysis of the <I>IL-18</I> gene, the CG haplotype was significantly more frequent in the GN group than the control group (61.5% <I>vs</I> 46.9%, <I>P</I> = 0.002). These results show that the −607CC genotype of the <I>IL-18</I> gene and the 405GG genotype of the <I>VEGF</I> gene are associated with susceptibility to and the development of primary GN.</P>

Regulation of cancer cell death by a novel compound, C604, in a c-Myc-overexpressing cellular environment

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>

Improvement of high-field J_c of MgB₂ wires by polymethyl-methacrylate doping

Park, G.C.,Hwang, S.M.,Lee, C.M.,Choi, J.H.,Joo, J.,Lim, J.H.,Kang, W.N.,Kim, C.J. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.suppl1

We applied polymethyl-methacrylate (PMMA) as a new doping material for MgB<SUB>2</SUB> and fabricated C-doped MgB<SUB>2</SUB> wires by in situ powder-in-tube (PIT) process. With increasing PMMA doping level, the transition temperature (T<SUB>c</SUB>) decreased and the MgO content increased, whereas the magnetic field dependence of the critical current density (J<SUB>c</SUB>) weakened. The MgB<SUB>2</SUB> wires doped with 3-10wt.% PMMA showed significantly higher J<SUB>c</SUB> by more than one order of magnitude than that of the undoped wire at 5K and 6.6T. These results confirmed the potential of PMMA as a promising material for the effective substitution of B by C in MgB<SUB>2</SUB>.

O-free polyacrylonitrile doping to improve the J_c(B) and H_c2 of MgB₂ wires

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>).

Ion scattering spectroscopy study of the Si(001)c(4x4)-C surface reconstruction

Park J. Y.,Chae K. H.,Choi D. S.,Kim J. Y.,Kim S. S.,Seo J. H.,Whang C. N. 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3

Reconstructed Si(001)c(4 4)-C surface has been studied by coaxial impact collision ion scattering spectroscopy (CAICISS). When 100L ethylene (C2H4) was exposed on Si(001)-(2 1) surface at 700 C, Si(001) dimer structures were changed by induced carbon (C) atoms. The experimental CAICISS spectra and simulation results reveal that the reconstructed Si(001)c(4 4)-C surface shows good agreement with the missing dimer model, rather than the Si-C heterodimer model, and adsorbed C atoms in uence only the reconstructed vertical plane of Si(001) surface. On comparing the azimuthal-scan curves for 100L C/Si(001) with those for clean Si(001), it can be suggested that C atoms occupy the fourth subsurface layer of Si(001) directly below the HB (bridge) site. These results are new evidence supporting the previous studies based on the C incorporation into Si(001) surface with missing dimers and the substitution of the fourth Si layers.

SIGN-R1, a C-type lectin, enhances apoptotic cell clearance through the complement deposition pathway by interacting with C1q in the spleen

MG Prabagar,Y Do,S Ryu,J-Y Park,H-J Choi,W-S Choi,TJ Yun,J Moon,I-S Choi,K Ko,K Ko,C Young Shin,C Cheong,Y-S Kang 한국당과학회 2013 한국당과학회 학술대회 Vol.2013 No.1

Complements, such as C1q and C3, and macrophages in the splenic marginal zone (MZMs) play pivotal roles in the efficient uptake and processing of circulating apoptotic cells. SIGN-R1, a C-type lectin that is highly expressed in a subpopulation of MZMs, regulates the complement fixation pathway by interacting with C1q, to fight blood-borne Streptococcus pneumoniae. Therefore, we examined whether the SIGN-R1-mediated classical complement pathway plays a role in apoptotic cell clearance and immune tolerance. SIGN-R1 first-bound apoptotic cells and this binding was significantly enhanced in the presence of C1q. SIGN-R1-C1q complex then immediately mediated C3 deposition on circulating apoptotic cells in the MZ, leading to the efficient clearance of them. SIGN-R1-mediated C3 deposition was completely abolished in the spleen of SIGN-R1 knockout (KO) mice. Given that SIGN-R1 is not expressed in the liver, we were struck by the finding that C3-deposited apoptotic cells were still found in the liver of wild-type mice, and dramatically reduced in the SIGN-R1 KO liver. In particular, SIGN-R1 deficiency caused delayed clearance of apoptotic cells and aberrant secretion of cytokines, such as TNF-α, IL-6, and TGF-β in the spleen as well as in the liver. In addition, anti-double- and single-stranded DNA antibody level was significantly increased in SIGN-R1-depleted mice compared with control mice. These findings suggest a novel mechanism of apoptotic cell clearance which is initiated by SIGN-R1 in the MZ and identify an integrated role of SIGN-R1 in the systemic clearance of apoptotic cells, linking the recognition of apoptotic cells, the opsonization of complements, and the induction of immune tolerance.

정상인 및 당뇨병환자에서의 경구당부하시 혈중 Insulin과 C-Peptide의 변동

이명철,고창순,최성재,김응진,민헌기 대한핵의학회 1977 핵의학 분자영상 Vol.11 No.1

저자들은 정상인 및 당뇨병환자에서 insulin과 C-peptide의 변동양상의 의의를 관찰하고 또한 비만이 insulin 반응에 영향을 끼치는 것을 보고자 정상인 15명 (비비만형 10명, 비만형 5명), 중등도당뇨병환자 22례 (비비만형 13례, 비만형 9례) 및 중증당뇨병환자 9례, 총 46명을 대상으로 경구적 당부하시험을 시행하고 각 혈중 insulin과 C-peptide를 방사면역법으로 측정하여 다음과 같은 결과를 얻었기에 보고하는 바이다. 1) 10명의 비비만형정상인에서의 insulin치는 공복시 및 100 gm 경구당부하후 30, 60, 90, 120분에서 각각 15.7±3.4, 48.3±9.8, 4.4±6.7, 37.4±6.5 및 26.0±4.2uU/ml(Mean±S.E.)이고 C-peptide는 각각 1.9±0.3, 3.9±0.6, 6.3±0.6, 5.7±0.5 및 4.0±0.5 ng/ml로서 insulin가 C-peptide 평행한 반응을 보였고 insulin은 30분에서 최고치를 나타낸 반면 C-peptide는 60분에서 최고치를 보였다. 2) 비만형정상인 5례에서 insulin은 각각 38.9±12.3, 59.5±12.3, 59.2±17.1, 56.1±20.0 및 48.4±17.2uU/ml이고 C-peptide는 각각 5.5±0.4, 6.8±0.5, 7.9±0.8, 7.9±0.8 및 7.8±2.0ng/ml로서 비비만형에 비하여 반응이 현저히 증가함을 보였다. 3) 13례의 비비만형중등도당뇨병환자의 혈장내 insulin은 각각 27.1±4.9, 44.1±6.0, 37.3±6.6, 35.5±8.1 및 34.7±10.7uU/ml이고 C-peptide는 각각 2.7±0.4, 4.9±0.7, 6.5±0.5, 7.0±0.3 및 6.7±1.0ng/ml로서 비비만형정상군에 비하여 insulin 및 C-peptide의 차이는 없으나 지연되는 양상을 보였다. 4) 비비만형중등도당뇨병환자 9명에서의 insulin은 각각 22.1±7.9, 80.0±19.3, 108.0±27.0, 62.0±17.6 및 55.5±10.1 uU/ml이었으며 C-peptide는 5.2±0.4, 8.0±1.0, 10.4±1.6, 10.4±1.7 및 10.0±10ng/ml로서 insulin과 C-peptide 반응이 비비만형중둥도당뇨병환자군에 비해 각각 항진됨을 볼 수 있었다. 5) 중증당뇨병환자 9례에서의 혈중 insulin은 8.0±3.8, 12.1±3.5, 16.8±4.6, 19.6±5.2 및 15.0±5.0uU/ml이며 C-peptide는 1.6±0.3, 2.4±0.4, 4.1±0.6, 4.0±0.8 및 4.5±0.7ng/ml로서 insulin과 C-peptide가 각각 현저히 감소하였다. 이 각 당뇨병환자군에서의 총 insulin 및 C-peptide 면적, 그리고 insulinogenic index와 C-peptide index를 산출한 결과 당뇨병정도에 따른 유의한 차이를 관찰하였다. The present study was undertaken to evaluate the significance of the insulin and the C-peptide rseponse to oral glucose loads in normal and diabetic subjects and to establish the effects of the obesity. In this study, the authors have measured plasma insulin and C-peptide by means of radioimmunoassay in 10 nonobese normal, 5 obese normal, 13 nonobese moderate diabetic patients, 9 obese moderate diabetic patients and 9 severe diabetic patients. The results obtained were as follows; 1) In 10 nonobese normal subjects, the plasma insulin level at fasting state and at 30, 60, 90, and 120 min after oral glucose loads were 15.7±3.4, 48.3±9.8, 40.4±6.7, 37.4±6.5 and 26.0±4.2uU/ml(Mean±S.E.) and C-peptide were 1.9±0.3, 3.9±0.6, 6.3±0.6, 5.7±0.5 and 4.0±0.5ng/ml. The change of C-peptide was found to go almost parallel with that of insulin and the insulin value reaches to the highest level at 30 min whereas C-peptide reaches to its peak at 60min. 2) The plasma insulin level in 5 obese normal subjects were 38.5±12.3, 59.2±17.1, 56.1±20.0 and 48.4±17.2 uU/ml and the C-peptide were 5.5±0.4, 6.8±0.5, 7.9±0.8, 7.9±0.8 and 7.8±2.0ng/ml. The insulin response appeared to be greater than nonobese normal subjects. 3) In 13 nonobese moderate diabetic patients, the plasma insulin levels were 27.1±4.9, 44.1±6.0, 37.3±6.6, 35.5±8.1 and 34.7±10.7uU/ml and the C-peptide levels were 2.7±0.4, 4.9±0.7, 6.5±0.5, 7.0±0.3 and 6.7±1.0ng/ml. There was little significance compared to nonobese normal groups but delayed pattern is noted. 4) In 9 obese moderated diabetic patients, the plasma insulin levels were 22.1±7.9, 80.0±19.3, 108.0±27.0, 62.0±17.6 and 55.5±10.luU/ml and the C-peptide levels were 5.2±0.4, 8.0±1.0, 10.4±1.6, 10.4±1.7 and 10.1±1.0ng/ml and its response was also greater than that of nonobese moderate diabetic patients. 5) The plasma insulin concentrations in 9 severe diabetic subjects were 8.0±3.8, 12.1±3.5, 16.8±4.6, 19.6±5.2 and 15.0±5.0uU/ml and the C-peptide levels were 1.6±0.3, 2.4/ml and the insulin and C-peptide responses were markedly reduced in severe diabetic groups. 6) There were significant differences between each groups of patients on the magnitude of total insulin or C-peptide areas, the insulinogenic index and the C-peptide index. $quot;

SIGN-R1, a C-type lectin, enhances apoptotic cell clearance through the complement deposition pathway by interacting with C1q in the spleen

Prabagar, M G,Do, Y,Ryu, S,Park, J-Y,Choi, H-J,Choi, W-S,Yun, T J,Moon, J,Choi, I-S,Ko, K,Ko, K,Young Shin, C,Cheong, C,Kang, Y-S Macmillan Publishers Limited 2013 Cell death and differentiation Vol.20 No.4

Complements, such as C1q and C3, and macrophages in the splenic marginal zone (MZMs) play pivotal roles in the efficient uptake and processing of circulating apoptotic cells. SIGN-R1, a C-type lectin that is highly expressed in a subpopulation of MZMs, regulates the complement fixation pathway by interacting with C1q, to fight blood-borne Streptococcus pneumoniae. Therefore, we examined whether the SIGN-R1-mediated classical complement pathway plays a role in apoptotic cell clearance and immune tolerance. SIGN-R1 first-bound apoptotic cells and this binding was significantly enhanced in the presence of C1q. SIGN-R1–C1q complex then immediately mediated C3 deposition on circulating apoptotic cells in the MZ, leading to the efficient clearance of them. SIGN-R1-mediated C3 deposition was completely abolished in the spleen of SIGN-R1 knockout (KO) mice. Given that SIGN-R1 is not expressed in the liver, we were struck by the finding that C3-deposited apoptotic cells were still found in the liver of wild-type mice, and dramatically reduced in the SIGN-R1 KO liver. In particular, SIGN-R1 deficiency caused delayed clearance of apoptotic cells and aberrant secretion of cytokines, such as TNF-α, IL-6, and TGF-β in the spleen as well as in the liver. In addition, anti-double- and single-stranded DNA antibody level was significantly increased in SIGN-R1-depleted mice compared with control mice. These findings suggest a novel mechanism of apoptotic cell clearance which is initiated by SIGN-R1 in the MZ and identify an integrated role of SIGN-R1 in the systemic clearance of apoptotic cells, linking the recognition of apoptotic cells, the opsonization of complements, and the induction of immune tolerance.

Radotinib induces high cytotoxicity in c-KIT positive acute myeloid leukemia cells

Heo, S.K.,Noh, E.K.,Kim, J.Y.,Jo, J.C.,Choi, Y.,Koh, S.,Baek, J.H.,Min, Y.J.,Kim, H. North-Holland 2017 European journal of pharmacology Vol.804 No.-

<P>Previously, we reported that radotinib, a BCR-ABL1 tyrosine kinase inhibitor, induced cytotoxicity in acute myeloid leukemia (AML) cells. However, the effects of radotinib in the subpopulation of c-KIT-positive AML cells were unclear. We observed that low-concentration radotinib had more potent cytotoxicity in c-KIT-positive cells than c-KIT-negative cells from AML patients. To address this issue, cell lines with high c-KIT expression, HEL92.1.7, and moderate c-KIT expression, H209, were selected. HEL92.1.7 cells were grouped into intermediate and high c-HIT expression populations. The cytotoxicity of radotinib against the HEL92.1.7 cell population with intermediate c-HIT expression was not different from that of the population with high c-KIT expression. When H209 cells were grouped into c-KIT expression-negative and c-HIT expression-positive populations, radotinib induced cytotoxicity in the c-KIT-positive population, but not the c-KIT-negative population. Thus, radotinib induces cytotoxicity in c-KIT-positive cells, regardless of the c-KIT expression intensity. Therefore, radotinib induces significant cytotoxicity in c-KIT-positive AML cells, suggesting that radotinib is a potential target agent for the treatment of c-KIT-positive malignancies including AML.</P>