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        Production of (S)-3-hydroxybutyrate by metabolically engineered Saccharomyces cerevisiae

        Yun, E.J.,Kwak, S.,Kim, S.R.,Park, Y.C.,Jin, Y.S.,Kim, K.H. Elsevier Science Publishers 2015 Journal of biotechnology Vol.209 No.-

        (S)-3-Hydroxybutyrate (S-3HB) can be used as a precursor for the synthesis of biodegradable polymers such as polyhydroxyalkanoate and stereo-specific fine chemicals such as antibiotics, pheromones, and drugs. For the production of S-3HB in yeast, the biosynthetic pathway of S-3HB from acetyl-CoA, consisting of the three enzymes, acetyl-CoA C-acetyltransferase (ACCT), acetoacetyl-CoA reductase (ACR), and 3-hydroxybutyryl-CoA thioesterase (HBT), was introduced into Saccharomyces cerevisiae. An engineered yeast strain overexpressing ERG10, hbd, and tesB genes not only exhibited enzyme activities of AACT, ACR, and HBT, but also produced S-3HB from ethanol. In order to increase the titer of S-3HB, a fed-batch fermentation based on pulse feeding of ethanol as a carbon source was performed, and a final S-3HB titer of 12.0g/L was achieved. This is the first report on the production of 3HB by engineered yeast, utilizing ethanol as the carbon source, suggesting that the industrially preferred S. cerevisiae can be a promising host for producing S-3HB.

      • SCISCIESCOPUS

        Melatonin enhances arsenic trioxide-induced cell death via sustained upregulation of Redd1 expression in breast cancer cells

        Yun, S.M.,Woo, S.H.,Oh, S.T.,Hong, S.E.,Choe, T.B.,Ye, S.K.,Kim, E.K.,Seong, M.K.,Kim, H.A.,Noh, W.C.,Lee, J.K.,Jin, H.O.,Lee, Y.H.,Park, I.C. North-Holland 2016 Molecular and cellular endocrinology Vol.422 No.-

        Melatonin is implicated in various physiological functions, including anticancer activity. However, the mechanism(s) of its anticancer activity is not well understood. In the present study, we investigated the combined effects of melatonin and arsenic trioxide (ATO) on cell death in human breast cancer cells. Melatonin enhanced the ATO-induced apoptotic cell death via changes in the protein levels of Survivin, Bcl-2, and Bax, thus affecting cytochrome c release from the mitochondria to the cytosol. Interestingly, we found that the cell death induced by co-treatment with melatonin and ATO was mediated by sustained upregulation of Redd1, which was associated with increased production of reactive oxygen species (ROS). Combined treatment with melatonin and ATO induced the phosphorylation of JNK and p38 MAP kinase downstream from Redd1 expression. Rapamycin and S6K1 siRNA enhanced, while activation of mTORC1 by transfection with TSC2 siRNA suppressed the cell death induced by melatonin and ATO treatment. Taken together, our findings suggest that melatonin enhances ATO-induced apoptotic cell death via sustained upregulation of Redd1 expression and inhibition of mTORC1 upstream of the activation of the p38/JNK pathways in human breast cancer cells.

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        S100A2 promoter-driven conditionally replicative adenovirus targets non-small-cell lung carcinoma

        Lee, K,Yun, S-T,Yun, C-O,Ahn, B-Y,Jo, E-C Macmillan Publishers Limited 2012 Gene Therapy Vol.19 No.10

        S100A2, a member of the S100 family of calcium-binding proteins, has been implicated in carcinogenesis as both a tumor suppressor and stimulator. Here, we characterized promoter activity of S100A2, generated an S100A2 promoter-driven conditionally replicative adenovirus (Ad/SA), and evaluated its anti-tumor activity in vitro and in vivo. Promoter activity of S100A2 was greatly restricted to tumor cells, and the S100A2 promoter bound with typical nuclear targets of epidermal growth factor receptor (EGFR) signaling. EGF-stimulated EGFR phosphorylation induced S100A2 expression and further activated E1A expression of Ad/SA, which was restored by EGFR signal inhibition in a concentration-dependent manner in non-small-cell lung carcinoma (NSCLC). In two EGFR-activated tumor xenograft animal models, Ad/SA exhibited potent anti-tumor activity, whereas cetuximab, an EGFR-targeting anticancer drug, was active transiently or ineffective. Combined treatment with cetuximab or cisplatin plus Ad/SA resulted in enhanced anti-tumor activity. Immunohistochemical analysis of tumor sections showed moderate-to-high grade signals for EGFR and adenovirus, and a reduction in viable cells in Ad/SA-treated tumors. Collectively, these results demonstrate that the S100A2 promoter-driven adenovirus is a potent inhibitor of cancers, and further suggest that S100A2 is a target gene of EGFR signaling pathway in NSCLC.

      • Wrinkle structures formed by formulating UV-crosslinkable liquid prepolymers

        Park, S.K.,Kwark, Y.J.,Nam, S.,Park, S.,Park, B.,Yun, S.,Moon, J.,Lee, J.I.,Yu, B.,Kyung, K.U. IPC Science and Technology Press 2016 Polymer Vol.99 No.-

        Artificial wrinkles have recently been in the spotlight due to their potential use in high-tech applications. A spontaneously wrinkled film can be fabricated from UV-crosslinkable liquid prepolymers. Here, we controlled the wrinkle formation by simply formulating two UV-crosslinkable liquid prepolymers, tetraethylene glycol bis(4-ethenyl-2,3,5,6-tetrafluorophenyl) ether (TEGDSt) and tetraethylene glycol diacrylate (TEGDA). The wrinkles were formed from the TEGDSt/TEGDA formulated prepolymer layers containing up to 30 wt% of TEGDA. The wrinkle formation depended upon the rate of photo-crosslinking reaction of the formulated prepolymers. The first order apparent rate constant, k<SUB>app</SUB>, was between ca. 5.7 x 10<SUP>-3</SUP> and 12.2 x 10<SUP>-3</SUP> s<SUP>-1</SUP> for the wrinkle formation. The wrinkle structures were modulated within the k<SUB>app</SUB> mainly due to variation in the extent of shrinkage of the formulated prepolymer layers with the content of TEGDA.

      • SCIESCOPUSKCI등재

        Comparison of Synthetic Lysine Sources on Growth Performance, Nutrient Digestibility and Nitrogen Retention in Weaning Pigs

        Ju, W.S.,Yun, M.S.,Jang, Y.D.,Choi, H.B.,Chang, J.S.,Lee, H.B.,Oh, H.K.,Kim, Y.Y. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.1

        We compared the effects of supplementing $L-lysine{\cdot}SO_4$ to L-lysine HCl on growth performance, nutrient digestibility and nitrogen retention in weaning pigs. A total of 96 crossbred pigs, weaned at $21{\pm}3$ days of age and with an average initial body weight (BW) $6.23{\pm}0.01kg$, were given one of 4 treatments, which translated into 6 replicates of 4 pigs in each pen. The animals were randomly assigned to four dietary treatments according to a randomized completely block design (RCBD) as follows: 1) control-no synthetic lysine, lysine deficient (0.80% total lysine); 2) L-C (= 0.2% L-lysine HCl); 3) K-L-S (= 0.332% $L-lysine{\cdot}SO_4$, A company); 4) C-L-S (= 0.332% $L-lysine{\cdot}SO_4$, B company). Diets were formulated with corn, soy bean meal, and corn gluten meal as the major ingredients, and all nutrients except the lysine met or exceeded NRC requirements (1998). The lysine content of supplemented synthetic lysine was the same in all treatment groups except the control. No clinical health problems associated with the dietary treatments were observed. During the entire experimental period, body weight, average daily gain (ADG) and feed efficiency (G:F ratio) increased (p<0.01) in pigs fed the experimental diets supplemented with L-lysine??HCl or $L-lysine{\cdot}SO_4$ produced by A company, irrespective of the two synthetic lysine sources. Although the supplementation of $L-lysine{\cdot}SO_4$ produced by B company tended to improve the ADG and G:F ratio, significant differences were not seen among all treatments and tended to be lower than the L-C (L-lysine HCl) and K-L-S ($L-lysine{\cdot}SO_4$ groups using the product from A company). The digestibility of crude protein (CP) was increased by the supplementation of synthetic lysine (p<0.05), irrespective of the L-lysine source (L-C, K-L-S, C-L-S). The results of this study showed that ADG, G:F ratio, and CP digestibility improved when $L-lysine{\cdot}SO_4$ or L-lysine HCl was supplemented into the weaning pigs' diet. There was a clear difference in efficacy between the two $lysine{\cdot}SO_4$ products based upon the growth performance of weaning pigs. Consequently, the bioavailability of $lysine{\cdot}SO_4$ products should be evaluated before supplementation of synthetic lysine in swine diets.

      • SCISCIESCOPUS

        High lipid composition of particulate organic matter in the northern Chukchi Sea, 2011

        Kim, B.K.,Lee, J.H.,Yun, M.S.,Joo, H.,Song, H.J.,Yang, E.J.,Chung, K.H.,Kang, S.H.,Lee, S.H. Pergamon Press 2015 Deep-sea research. Part II, Topical studies in oce Vol.120 No.-

        We investigated the biochemical compositions (lipids, proteins, and carbohydrates) of particulate organic matter (POM) as a potential food source in the northern Chukchi Sea. We aimed to understand physiological status of phytoplankton, determine important controlling factors, and estimate the energetic contents of POM. The major inorganic nutrients were generally depleted at upper mixed-layer depth (>20m). The average chlorophyll a (chl-a) concentration was 31.9mgm<SUP>-2</SUP> (S.D.=+/-31.3mgm<SUP>-2</SUP>) in this study, significantly higher than that reported previously in the northern Chukchi Sea. Small phytoplankton (0.7-5@?m) accounted for 65.9% of total chl-a concentration. The overall average compositions of lipids, carbohydrates, and proteins were 50% (S.D.=+/-10.7%), 35% (S.D.=+/-11.0%), and 15% (S.D.=+/-11.2%) for POM, respectively. Along with other evidence (e.g., low N:P and protein-carbohydrate ratios), the high lipid and low protein compositions of POM in this study suggests that phytoplankton might have had a nitrogen limitation and/or stationary growth phase in the northern Chukchi Sea during the cruise period, 2011. The overall average calorific content of food material (FM) was 149.2μgL<SUP>-1</SUP> (S.D.=+/-36.5μgL<SUP>-1</SUP>) or 1.0Kcalm<SUP>-3</SUP> (S.D.=+/-0.2Kcalm<SUP>-3</SUP>). The relatively higher calorific contents in the northern Chukchi Sea were due to high lipid contributions and the considerably high calorific content of FM per POC.

      • SCISCIESCOPUS

        Induction of bone formation by <i>Escherichia coli</i>‐expressed recombinant human bone morphogenetic protein‐2 using block‐type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models

        Park, J‐,C.,So, S,S.,Jung, I‐,H.,Yun, J‐,H.,Choi, S,H.,Cho, K,S.,Kim, C‐,S. Blackwell Publishing Ltd 2011 Journal of periodontal research Vol.46 No.6

        <P><I>Park J‐C, So S‐S, Jung I‐H, Yun J‐H, Choi S‐H, Cho K‐S, Kim C‐S. Induction of bone formation by</I> Escherichia coli<I>‐expressed recombinant human bone morphogenetic protein‐2 using block‐type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models. J Periodont Res 2011; 46: 682–690. © 2011 John Wiley & Sons A/S</I></P><P><B>Background and Objective: </B> The potential of the <I>Escherichia coli</I>‐expressed recombinant human bone morphogenetic protein‐2 (ErhBMP‐2) to support new bone formation/maturation using a block‐type of macroporous biphasic calcium phosphate (bMBCP) carrier was evaluated in an orthotopic and ectopic rat model.</P><P><B>Material and Methods: </B> Critical‐size (Φ 8 mm) calvarial defects and subcutaneous pockets in 32 Sprague–Dawley rats received implants of rhBMP‐2 (2.5 μg) in a bMBCP carrier or bMBCP alone (control). Implant sites were evaluated using histological and histometric analysis following 2‐ and 8‐wk healing intervals (eight animals/group/interval).</P><P><B>Results: </B> ErhBMP‐2/bMBCP supported significantly greater bone formation at 2 and 8 wk (10.8% and 25.4%, respectively) than the control at 2 and 8 wk (5.3% and 14.0%, respectively) in calvarial defects (<I>p</I> < 0.01). Bone formation was only observed for the ErhBMP‐2/bMBCP ectopic sites and was significantly greater at 8 wk (7.5%) than at 2 wk (4.5%) (<I>p</I> < 0.01). Appositional and endochondral bone formation was usually associated with a significant increase in fatty marrow at 8 wk. The bMBCP carrier showed no evidence of bioresorption.</P><P><B>Conclusion: </B> ErhBMP‐2/bMBCP induced significant bone formation in both calvarial and ectopic sites. Further study appears to be required to evaluate the relevance of the bMBCP carrier.</P>

      • SCISCIESCOPUS

        Geochemical modeling of CO<sub>2</sub>-water-rock interactions for two different hydrochemical types of CO<sub>2</sub>-rich springs in Kangwon District, Korea

        Choi, B.Y.,Yun, S.T.,Kim, K.H.,Choi, H.S.,Chae, G.T.,Lee, P.K. Elsevier 2014 Journal of geochemical exploration Vol.144 No.1

        Naturally outflowing CO<SUB>2</SUB>-rich springs are a natural analogue of the seepage of sequestered CO<SUB>2</SUB> in geological storage sites. In Kangwon district of South Korea, two hydrochemically different types of CO<SUB>2</SUB>-rich springs (i.e., Ca-HCO<SUB>3</SUB>-type and Na-HCO<SUB>3</SUB>-type) occur together in a granitic terrain. Hydrochemical and water-isotope data (i.e., δ<SUP>18</SUP>O-δD and tritium) show that Na-HCO<SUB>3</SUB>-type springs have experienced significant silicate weathering processes over a long residence time at depths, while Ca-HCO<SUB>3</SUB>-type springs were formed by the mixing of Na-HCO<SUB>3</SUB>-type springs with shallow groundwater during ascent. In this study, diverse geochemical models including mixing, ion exchange and reaction path were investigated to verify the geochemical processes accounting for the occurrence of two contrasting types of CO<SUB>2</SUB>-rich springs. The mixing and ion exchange models reveal that Ca-HCO<SUB>3</SUB>-type springs are well explained by reverse cation exchange occurring during the mixing of Na-HCO<SUB>3</SUB>-type springs with shallow groundwater. The Na-HCO<SUB>3</SUB>-type springs are well explained by the reaction path modeling including the dissolution of silicate minerals (plagioclase, K-feldspar and biotite) and the precipitation of secondary minerals (calcite, kaolinite, muscovite and Mg-beidellite), implying that dissolved carbon is sequestered by calcite precipitation (i.e., mineral trapping). However, the concentrations of K in our modeling results are far below those of K observed in Na-HCO<SUB>3</SUB>-type springs, because of the precipitation of muscovite considered in the model, suggesting the partial disequilibrium state of the aquifer during the hydrolysis of K-feldspar under high P<SUB>CO'2</SUB> conditions. This result implies that to better predict long-term CO<SUB>2</SUB>-water-rock interactions in a geological storage site with abundant K-feldspar, the secondary K-bearing minerals should be carefully predicted, because a target aquifer can be far from chemical equilibrium during the storage period. This study shows that geochemical modeling can be effectively used to predict the hydrochemical changes of groundwater during long-term CO<SUB>2</SUB>-water-rock interactions and subsequent leakage toward surface in K-feldspar rich aquifer, although it should be included in a fully coupled computational approach between fluid flow, heat transfer and reactive mass transport processes in the future research.

      • Streptococcus gordonii induces nitric oxide production through its lipoproteins stimulating Toll-like receptor 2 in murine macrophages

        Kim, H.Y.,Baik, J.E.,Ahn, K.B.,Seo, H.S.,Yun, C.H.,Han, S.H. Pergamon Press 2017 Molecular immunology Vol.82 No.-

        <P>Streptococcus gordonii, a Gram-positive commensal in the oral cavity, is an opportunistic pathogen that can cause endodontic and systemic infections resulting in infective endocarditis. Lipoteichoic acid (LTA) and lipoprotein are major virulence factors of Gram-positive bacteria that are preferentially recognized by Toll-like receptor 2 (TLR2) on immune cells. In the present study, we investigated the effect of S. gordonii LTA and lipoprotein on the production of the representative inflammatory mediator nitric oxide (NO) by the mouse macrophages. Heat-killed S. gordonii wild-type and an LTA-deficient mutant (Delta ltaS) but not a lipoprotein-deficient mutant (Delta lgt) induced NO production in mouse primary macrophages and the cell line, RAW 264.7.S. gordonii wild-type and Delta ItaS also induced the expression of inducible NO synthase (iNOS) at the mRNA and protein levels. In contrast, the Delta lgt mutant showed little effect under the same condition. Furthermore, S. gordonii wild-type and Delta ItaS induced NF-kappa B activation, STAT1 phosphorylation, and IFN-beta expression, which are important for the induction of iNOS gene expression, with little activation by Delta lgt. S. gordonii wild-type and Delta ltaS showed an increased adherence and internalization to RAW 264.7 cells compared to Delta lgt. In addition, S. gordonii wild-type and AIMS, but not Delta lgt, substantially increased TLR2 activation while none of these induced NO production in TLR2-deficient macrophages. Triton X-114-extracted lipoproteins from S. gordonii were sufficient to induce NO production. Collectively, we suggest that lipoprotein is an essential cell wall component of S. gordonii to induce NO production in macrophages through TLR2 triggering NF-kappa B and STAT1 activation. (C) 2016 Elsevier Ltd. All rights reserved.</P>

      • SCIESCOPUSKCI등재

        Exchange Bias in Cr<sub>2</sub>O<sub>3</sub>/Fe<sub>3</sub>O<sub>4</sub> Core/Shell Nanoparticles

        Yun, B.K.,Koo, Y.S.,Jung, J.H. The Korean Magnetics Society 2009 Journal of Magnetics Vol.14 No.4

        We report the exchange bias in antiferromagnet/ferrimagnet $Cr_2O_3/Fe_3O_4$ core/shell nanoparticles. The magnetic field hysteresis curve for $Cr_2O_3/Fe_3O_4$ nanoparticles after field-cooling (FC) clearly showed both horizontal ($H_{EB}{\sim}$610 Oe) and vertical (${\Delta}M{\sim}$5.6 emu/g) shifts at 5 K. These shifts disappeared as the temperature increased toward the Neel temperature of $Cr_2O_3\;(T_N{\sim}$307 K). The $H_{EB}\;and\;{\Delta}M$ values were sharply decreased between the $1^{st}\;and\;the\;2^{nd}$ magnetic field cycles, and then slowly decreased with further cycling. These results are discussed in terms of the formation of single domains with pinned, uncompensated, antiferromagnetic spin and their evolution into multi-domains with cycling.

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