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유착에 의한 AGS 및 Hep-G2 세포 표면 구조의 변화
박동규 ( D. K. Park ),전훈재 ( H. J. Chun ),박재홍 ( J. H. Park ),박철희 ( C. H. Park ),진윤태 ( Y. T. Jeen ),이홍식 ( H. S. Lee ),이상우 ( S. W. Lee ),엄순호 ( S. H. Um ),최재현 ( J. H. Choi ),김창덕 ( C. D. Kim ),류호상 ( H. S. Ryu 대한소화기학회 2002 대한소화기학회 춘계학술대회 Vol.2002 No.-
<목적> 최근 H. pylori 유착에 의한 세포 표면 구조의 변화에 관한 연구가 시도되어지고 있으나 actin 의 변화여부 및 그 특성에 관해서는 아직 명확히 정립되지 못한 실정이다. Rho GTPase는 세포 표면의 미세돌기인 microvilli, filopodia 및 membrane ruffle의 형성과 관련이 있으며, 최근 AGS 세포에서 H. pylori가 Rac activation에 의하여 membrane ruffle을 형성한다는 것과 Rac
Um, D.H.,Kim, T.Y.,Kwon, O.C. Pergamon Press 2014 ENERGY Vol.73 No.-
Power and hydrogen (H<SUB>2</SUB>) production by burning and reforming ammonia (NH<SUB>3</SUB>) in a micro-TPV (microscale-thermophotovoltaic) device integrated with a micro-reformer is studied experimentally. A heat-recirculating micro-emitter with the cyclone and helical adapters that enhance the residence time of fed fuel-air mixtures and uniform burning burns H<SUB>2</SUB>-added NH<SUB>3</SUB>-air mixtures. A micro-reformer that converts NH<SUB>3</SUB> to H<SUB>2</SUB> using ruthenium as a catalyst surrounds the micro-emitter as a heat source. The micro-reformer is surrounded by a chamber, the inner and outer walls of which have installations of gallium antimonide photovoltaic cells and cooling fins. For the micro-reformer-integrated micro-TPV device the maximum overall efficiency of 8.1% with electrical power of 4.5 W and the maximum NH<SUB>3</SUB> conversion rate of 96.0% with the H<SUB>2</SUB> production rate of 22.6 W (based on lower heating value) are obtained, indicating that the overall efficiency is remarkably enhanced compared with 2.0% when the micro-TPV device operates alone. This supports the potential of improving the overall efficiency of a micro-TPV device through integrating it with a micro-reformer. Also, the feasibility of using NH<SUB>3</SUB> as a carbon-free fuel for both burning and reforming in practical micro power and H<SUB>2</SUB> generation devices has been demonstrated.
S6K1 controls pancreatic 관 cell size independently of intrauterine growth restriction.
Um, Sung Hee,Sticker-Jantscheff, Melanie,Chau, Gia Cac,Vintersten, Kristina,Mueller, Matthias,Gangloff, Yann-Gael,Adams, Ralf H,Spetz, Jean-Francois,Elghazi, Lynda,Pfluger, Paul T,Pende, Mario,Bernal- American Society for Clinical Investigation 2015 The Journal of clinical investigation Vol.125 No.7
<P>Type 2 diabetes mellitus (T2DM) is a worldwide heath problem that is characterized by insulin resistance and the eventual loss of 관 cell function. As recent studies have shown that loss of ribosomal protein (RP) S6 kinase 1 (S6K1) increases systemic insulin sensitivity, S6K1 inhibitors are being pursued as potential agents for improving insulin resistance. Here we found that S6K1 deficiency in mice also leads to decreased 관 cell growth, intrauterine growth restriction (IUGR), and impaired placental development. IUGR is a common complication of human pregnancy that limits the supply of oxygen and nutrients to the developing fetus, leading to diminished embryonic 관 cell growth and the onset of T2DM later in life. However, restoration of placental development and the rescue of IUGR by tetraploid embryo complementation did not restore 관 cell size or insulin levels in S6K1-/- embryos, suggesting that loss of S6K1 leads to an intrinsic 관 cell lesion. Consistent with this hypothesis, reexpression of S6K1 in 관 cells of S6K1-/- mice restored embryonic 관 cell size, insulin levels, glucose tolerance, and RPS6 phosphorylation, without rescuing IUGR. Together, these data suggest that a nutrient-mediated reduction in intrinsic 관 cell S6K1 signaling, rather than IUGR, during fetal development may underlie reduced 관 cell growth and eventual development of T2DM later in life.</P>
ASXL2 promotes proliferation of breast cancer cells by linking ERα to histone methylation
Park, U-H,Kang, M-R,Kim, E-J,Kwon, Y-S,Hur, W,Yoon, S K,Song, B-J,Park, J H,Hwang, J-T,Jeong, J-C,Um, S-J Macmillan Publishers Limited 2016 Oncogene Vol.35 No.28
<P>Estrogen receptor alpha (ER alpha) has a pivotal role in breast carcinogenesis by associating with various cellular factors. Selective expression of additional sex comb-like 2 (ASXL2) in ER alpha-positive breast cancer cells prompted us to investigate its role in chromatin modification required for ERa activation and breast carcinogenesis. Here, we observed that ASXL2 interacts with ligand E2-bound ERa and mediates ERa activation. Chromatin immunoprecipitation-sequencing analysis supports a positive role of ASXL2 at ERa target gene promoters. ASXL2 forms a complex with histone methylation modifiers including LSD1, UTX and MLL2, which all are recruited to the E2-responsive genes via ASXL2 and regulate methylations at histone H3 lysine 4, 9 and 27. The preferential binding of the PHD finger of ASXL2 to the dimethylated H3 lysine 4 may account for its requirement for ERa activation. On ASXL2 depletion, the proliferative potential of MCF7 cells and tumor size of xenograft mice decreased. Together with our finding on the higher ASXL2 expression in ERa-positive patients, we propose that ASXL2 could be a novel prognostic marker in breast cancer.</P>
Photoelectrochemical water splitting employing a tapered silicon nanohole array
Jung, J. Y.,Choi, M.,Zhou, K.,Li, X.,Jee, S. W.,Um, H. D.,Park, M. J.,Park, K. T.,Bang, J.,Lee, J. H. Royal Society of Chemistry 2014 Journal of Materials Chemistry A Vol.2 No.3
An effective photocathode adopting a tapered Si nanohole (SiNH) array has been developed for photoelectrochemical water splitting. The tapered feature of SiNH photocathodes resulted in a gradation of the refractive indices between Si and air, such that the mismatching of optical impedance was alleviated and light absorption was enhanced. Adjusting the depth of the SiNHs successfully simulated the number of dielectric layers, optimizing the destructive interference for an antireflective coating (ARC). Only a 200 nm-thin NH array was required to absorb similar to 96% of solar spectral irradiance for photoelectrochemical applications. This thickness also minimized the undesirable surface recombination loss. When compared to a similar system using a planar technology, the formation of NHs was observed to cause an increase in the optical bandgap. This could generate a surface-passivation effect, resulting in a lowering of dark current and an increase in photovoltage, which could be utilized for an anodic shift of the onset voltage. Due to the addition of tapered SiNHs, the photogenerated current was improved by similar to 30% (similar to 33 mA cm(-2)) compared to a planar counterpart (similar to 25 mA cm(-2)), while the overpotential required for H-2 evolution was reduced.
김진현 ( J. H. Kim ),김태욱 ( T. W. Kim ),김설하 ( S. H. Kim ),이황규 ( W. K. Lee ),엄덕호 ( D. H. Um ),이상훈 ( S. H. Lee ) 한국농업기계학회 2020 한국농업기계학회 학술발표논문집 Vol.25 No.2
지중관수의 근본적인 목적은 용수를 절감하고 수분이 작물의 뿌리에 충분히 공급하기 위함이다. 그러나 지중관수를 통하여 뿌리가 수분을 충분히 공급받았는지에 대해서는 토양을 파서 수분을 확인하기 전에는 알 수가 없다. 그래서 농민들은 비록 관수효율이 낮아도 지표면에 흥건히 공급하는 경향이 있다. 지표면 관수는 증발로 인해 약 30~40%의 수분이 소실되고 지표면 이외의 세근이 몰려있는 근권까지 공급하려면 더 많은 용수를 공급해야 가능하다. 지중관수는 여러 연구에서 용수의 절감과 수확의 증대 부분은 확인이 되었다. 그러나 동일한 용수를 공급하더라도 용수의 효율을 높이기 위해 단위시간당 얼마의 량을 공급하는 것이 적절한지에 대한 연구는 거의 이루어지지 않았다. 주된 이유는 토양의 물리성에 따라 표준화가 불가능하고 관수의 공급 방법과 데이터의 수집 등에서 오차가 늘 발생할 수 있기 때문이다. 본 연구에서는 미사질양토와 사질토에서 지중 30cm 내부에 4000cc를 2L/H, 4L/H, 8L/H의 Botton type 관수기를 통하여 공급하였을 때, 작물생육에 적용하기 가장 유리한 것은 2L/H라는 것을 확인하였다. 따라서 2L/H의 관수기에서 4000cc 이상 공급할 경우를 예측하여 재배작물(콩)의 생육시기별 근권에 가장 적합한 용수의 공급방법을 설계하였다. 콩의 생육시기는 뿌리가 수직으로 30~40cm 정도 성장하는 크기를 중심으로 설정하였다. 따라서 파종후 10일, 20일, 30일의 근권에 지중관수 용수의 공급을 설계하였다. 토양습윤 양상은 미사질양토와 사질토 모두 단위시간당 공급량이 작을수록 지표면 가까이 상승하므로 생육 초기와 중기까지 단위시간당 용수 공급량이 2L/H가 가장 유리하였다. 파종 후 10일에는 8000cc의 공급도 가능하였고, 20일에는 5000~6000cc, 30일 이후에는 4000cc의 용수가 공급되어도 충분할 것으로 판단되었다.
Gelation of graphene oxides induced by different types of amino acids
Ahn, H.,Kim, T.,Choi, H.,Yoon, C.,Um, K.,Nam, J.,Ahn, K.H.,Lee, K. Pergamon Press ; Elsevier Science Ltd 2014 Carbon Vol.71 No.-
We have investigated gelation of graphene oxide (GO) sheets induced by amino acids. For gelation of single layer GO sheets, six different types of amino acids were added to GO suspension as gelators. To understand gelation mechanism, we varied the concentration and type of amino acids as well as the pH of suspension, and monitored the morphology and rheological properties of reaction mixtures. Gelation was observed in acidic pH only with three types of amino acids (arginine, tryptophan, and cysteine) whereas no gel was formed at other pH values (neutral and basic). As the type of amino acid was varied, both the binding strength between amino acid and GO and the moduli (G' and G'') of reaction mixtures followed the same order, arginine>cysteine>tryptophan>asparagine>aspartic acid>glycine. To rationalize these results, we considered interactions between amino acid side chains and GO sheets (i.e., electrostatic interaction, π-π stacking, and hydrogen bonding), and found that the hydrogel formed by electrostatic attraction with arginine exhibited shorter gel time and larger moduli than the other samples. Finally, synthesis of GO hydrogel at physiological pH was demonstrated by increasing the concentration of GO sheets.
Kim, T.,Cho, S.,Woo, H. M.,Lee, S. M.,Lee, J.,Um, Y.,Seo, J. H. Springer Science + Business Media 2017 Applied microbiology and biotechnology Vol.101 No.7
<P>Conversion of crude glycerol derived from biodiesel processes to value-added chemicals has attracted much attention. Herein, Raoultella ornithinolytica B6 was investigated for the high production of 2,3-butanediol (2,3-BD) from glycerol without 1,3-propanediol (1,3-PD) formation, a by-product hindering 2,3-BD purification. By evaluating the effects of temperature, agitation speed, and pH control strategy, the fermentation conditions favoring 2,3-BD production were found to be 25 A degrees C, 400 rpm, and pH control with a lower limit of 5.5, respectively. Notably, significant pH fluctuations which positively affect 2,3-BD production were generated by simply controlling the lower pH limit at 5.5. In fed-batch fermentation under those conditions, R. ornithinolytica B6 produced 2,3-BD up to 79.25 g/L, and further enhancement of 2,3-BD production (89.45 g/L) was achieved by overexpressing homologous 2,3-BD synthesis genes (the budABC). When pretreated crude glycerol was used as a sole carbon source, R. ornithinolytica B6 overexpressing budABC produced 78.10 g/L of 2,3-BD with the yield of 0.42 g/g and the productivity of 0.62 g/L/h. The 2,3-BD titer, yield, and productivity values obtained in this study are the highest 2,3-BD production from glycerol among 1,3-PD synthesis-deficient 2,3-BD producers, demonstrating R. ornithinolytica B6 as a promising 2,3-BD producer from glycerol.</P>