Potential roles of D-serine and serine racemase in experimental temporal lobe epilepsy

Ryu, H.J.,Kim, J.-E.,Yeo, S.-I.,Kim, D.-S.,Kwon, O.-S.,Choi, S.Y.,Kang, T.-C. Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of neuroscience research Vol.88 No.11

<P>To confirm the roles of D-serinergic gliotransmission in epilepsy, we investigated the relationship between spatiotemporally specific glial responses and the D-serine/serine racemase system in mesial temporal structures following status epilepticus (SE). In control animals, D-serine and serine racemase immunoreactivities were detected mainly in astrocytes. After SE, D-serine and serine racemase immunoreactivities were increased in astrocytes. Double-immunofluorescence study revealed that up-regulation of serine racemase immunoreactivity was relevant not to D-serine immunoreactivity but to nestin or vimentin immunoreactivity. Neither D-serine nor serine racemase was found in naïve or reactive microglia. In addition, phosphorylated N-methyl-D-aspartate (NMDA) receptor subunit 1 (pNR1-Ser896) immunoreactivity in the hippocampus was increased compared with controls. Increased D-serine immunoreactivity showed direct correlation with the phosphorylation of Ser896 of NR1. Given the findings of our previous study, these findings suggest that D-serine and serine racemase in astrocytes may play roles in neuronal hyperexcitability via a cooperative activation of NMDA receptors. Furthermore, serine racemase may be involved in migration and differentiation of immature astrocytes, which is relevant to reactive astrogliosis. © 2010 Wiley-Liss, Inc.</P>

Exendin-4 induction of cyclin D1 expression in INS-1 beta-cells: involvement of cAMP-responsive element.

Kim, M-J,Kang, J-H,Park, Y G,Ryu, G R,Ko, S H,Jeong, I-K,Koh, K-H,Rhie, D-J,Yoon, S H,Hahn, S J,Kim, M-S,Jo, Y-H Journal of Endocrinology, Ltd. [etc.] 2006 The Journal of endocrinology Vol.188 No.3

<P>Glucagon-like peptide-1 (GLP-1) and its analog exendin-4 (EX) have been considered as a growth factor implicated in pancreatic islet mass increase and beta-cell proliferation. This study aimed to investigate the effect of EX on cyclin D1 expression, a key regulator of the cell cycle, in the pancreatic beta-cell line INS-1. We demonstrated that EX significantly increased cyclin D1 mRNA and subsequently its protein levels. Although EX induced phosphorylation of Raf-1 and extracellular-signal-regulated kinase (ERK), both PD98059 and exogenous ERK1 had no effect on the cyclin D1 induction by EX. Instead, the cAMP-elevating agent forskolin induced cyclin D1 expression remarkably and this response was inhibited by pretreatment with H-89, a protein kinase A (PKA) inhibitor. Promoter analyses revealed that the cAMP-responsive element (CRE) site (at position -48; 5'-TAACGTCA-3') of cyclin D1 gene was required for both basal and EX-induced activation of the cyclin D1 promoter, which was confirmed by site-directed mutagenesis study. For EX to activate the cyclin D1 promoter effectively, CRE-binding protein (CREB) should be phosphorylated and bound to the putative CRE site, according to the results of electrophoretic mobility shift and chromatin immunoprecipitation assays. Lastly, a transfection assay employing constitutively active or dominant-negative CREB expression plasmids clearly demonstrated that CREB was largely involved in both basal and EX-induced cyclin D1 promoter activities. Taken together, EX-induced cyclin D1 expression is largely dependent on the cAMP/PKA signaling pathway, and EX increases the level of phosphorylated CREB and more potently trans-activates cyclin D1 gene through binding of the CREB to the putative CRE site, implicating a potential mechanism underlying beta-cell proliferation by EX.</P>

pH-Controlled Synthesis of Cephalexin by a Purified Acetobacter turbidans Ampicillin Acylase

NAM, DOO HYUN,RYU, YEON WOO,RYU, DEWEY D. Y. 영남대학교 약품개발연구소 2001 영남대학교 약품개발연구소 연구업적집 Vol.11 No.-

It has been known that, in enzymatic synthesis of cephalexin, the conversion yield was reduced by high loading of ampiicillin acylase. In order to elucidate this phenomena, pH-controlled synthesis of cephalexin was examined using a purified Acetobacter turbidans acylase. When the pH of the reaction mixture was maintained at 6.20±0.04, the reduction of the maximal conversion rate was not observed even with high enzyme loading. The kinetic parameters also suggest that pH drop during the enzymatic synthesis of cephalexin was mainly attributed to the rapid hydrolysis of D-a-phenylglycine methyl ester to D-a-phenylglycine, rather than the disappearance of 7-amino-3-deacetoxycephalosporanic acid for cephalexin synthesis. At highter molar ratio of two substrates. [D-a-phenylglycine methyl ester]/[7-amino-3-deacetoxycephalosporanic acid], the conversion rate was also elevated under pH-controlled enzymatic synthesis, which implies that the main reason for the pH drop is due to the production of D-a-phenylglycine. In order to reduce the hydrolysis of D-a-phenylglycine methyl ester, the effect of a water-methanol cosolvent system on the conversion profile was also examined. Even though the conversion rate was increased in 10% methanol solution, a higher than 16% methanol in the reaction mixture caused an inactivation of enzyme.

pH-Controlled Synthesis of Cephalexin by a Purified Acetobacter turbidans Ampicillin Acylase

NAM, DOO HYUN,RYU, YEON WOO,DEWEY D. Y. RYU 한국미생물 · 생명공학회 2001 Journal of microbiology and biotechnology Vol.11 No.2

It has been known that, in enzymatic synthesis of cephalexin, the conversion yield was reduced by high loading of ampicillin acylase. In order to elucidate this phenomena, pH-controlled synthesis of cephalexin was examined using a purified Acetobacter turbidans acylase. When the pH of the reaction mixture was maintained at 6.20±0.04, the reduction of the maximal conversion rate was not observed even with high enzyme loading. The kinetic parameters also suggest that pH drop during the enzymatic synthesis of cephalexin was mainly attributed to the rapid hydrolysis of D-α-phenylglycine methyl ester to D-α-phenylglycine, rather than the disappearance of 7-amino-3-deacetoxycephalosporanic acid for cephalexin synthesis. At higher molar ratio of two substrates, [D-α-phenylglycine methyl esterl/[7-amino-3-deacetoxycephalosporanic acid], the conversion rate was also elevated under pH-controlled enzymatic synthesis, which implies that the main reason for the pH drop is due to the production of D-α-phenylglycine. In order to reduce the hydrolysis of D-α-phenylglycine methyl ester, the effect of a water-methanol cosolvent system on the conversion profile was also examined. Even though the conversion rate was increased in 10% methanol solution, a higher than 16% methanol in the reaction mixture caused an inactivation of enzyme.

A Study of Ferroelectric Properties in NaxK1xNbO3 Ceramic Compounds

D.H. Cho,M.S. Jang,조채용,J.G. Choi,J.P. Kim,M.K. Ryu,S.S. Park,S.Y. Cho 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1

The dielectric properties and the behavior of phase transition in the NaxK1xNbO3 ceramic system were investigated. The temperature and composition parameter (x ) dependence of the dielectric constants and the loss tangent of the system were measured. The dielectric constant was the highest and the loss tangent of the sample was the lowest at x = 0.52. The dielectric constant of Na0:52K0:48NbO3 ceramics becomes broadened and the transition temperature shifts toward a higher temperature with an increase in the measuring frequency at the Curie temperature. The remanent polarization (Pr) and coercive eld (Ec) were obtained from the D-E hysteresis loop at room temperature. A typical hysteresis loop of a sample of composition parameter x = 0.52 exhibits a remanent polarization of 10 C/cm2 and a coercive eld of 8.4 kV/cm.

Vitamin D-binding protein interacts with Aβ and suppresses Aβ-mediated pathology

Moon, M,Song, H,Hong, H J,Nam, D W,Cha, M-Y,Oh, M S,Yu, J,Ryu, H,Mook-Jung, I Macmillan Publishers Limited 2013 CELL DEATH AND DIFFERENTIATION Vol.20 No.4

The level of vitamin D-binding protein (DBP) is increased in the cerebrospinal fluid of patients with Alzheimer’s disease (AD), suggesting a relationship with its pathogenesis. In this study, we investigated whether and how DBP is related to AD using several different approaches. A pull-down assay and a surface plasmon resonance binding assay indicated direct interactions between purified DBP and amyloid beta (Aβ), which was confirmed in the brain of AD patients and transgenic AD model mice by immunoprecipitation assay and immunohistochemical double-staining method. Moreover, atomic force microscopic examination revealed that DBP reduced Aβ aggregation in vitro. DBP also prevented Aβ-mediated death in cultured mouse hippocampal HT22 cell line. Finally, DBP decreased Aβ-induced synaptic loss in the hippocampus and rescued memory deficits in mice after injection of Aβ into the lateral ventricle. These results provide converging evidence that DBP attenuates the harmful effects of Aβ by a direct interaction, and suggest that DBP is a promising therapeutic agent for the treatment of AD.

渦流室式 디젤機關에서 噴射노즐 形壯과 超音波 에너지 附加 디젤油의 性能特性에 關한 硏究

최두석(D. S. Choi),박종규(J. k. Park),김봉석(B. S. Kim),류정인(J. I. Ryu) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.6_2

The objectives of this study were to investigate the atomization characteristics and the engine performance characteristics using the change of injection nozzle form and ultrasonic-energy-added diesel fuel.<br/> 1. To evaluate the effect of ulrasonic energy and the change of injection nozzle form, droplet size<br/> measurements earned out using Malvern system. 2. To analyze the change of ultrasonic-energy-added diesel fuel, chemical analysis and physical analysis earned out using 'H-NMR spectrum, viscosity system and surface tension system.<br/> 3. In the diesel engine test, there were results about engine performance and exhaust emission.<br/> In Summary, the results of this study indicate that ultrasonic-energy-added diesel fuel induced beneficial changes in SMD, engine performance and exhaust emission. And the B type was excellent in all type of injection nozzle.

Studies on the Detection of mecA Gene and Distribution of Enterotoxin Genes in Pathogenic Staphylococci Isolated from Korea Using Molecular Biologic Technique

Whang, S. C.,Lee, D. H.,Ryu, J. R.,Jung, S. K. 高麗大學校 倂設 保健大學 保健科學硏究所 1997 保建科學硏究論集 Vol.6 No.1

본 연구에서는 입상 검체에서 발견되는 병원성 포도상구균(S. aureus)과 methicillin 내성 포도상구균(MRSA)에서 각각 nurc과 mecA 유전자, 장독소인 enterotoxin A에서 enterotoxin E를 encoding하는 유전자들과 toxic shock syndrome toxin(tst) 유전자를 빠르개 탐지하고 독소형의 국내·외의 역학적인 분포를 조사하기 위하여 multiplex PCR을 수행하였다. 210개의 MRSA에서 두 개의 균주가 mecA 유전자 음성을 보인 것을 제외하고 모두 nuc유전자와 mecA유전자 양성을 나타냈다. 이 중 10개(80.5%)가 한 게 흑은 그 이상의 장독소에 대한 유전자를 지니고 있었으며 다른 41개 균주(19.5%)는 장독소 유전자에 대해 양성을 나타내지 않았다. 장독소A 유전자(sea)는 분리균 중 50.5%(n=105)에서 유전자가 중폭되었고 seb는 14.료쏭(n=30), sec는 23.3% (n=49), sed는 10.0%(n=21) 그리고 tst는 12.4%(n=26)가 증폭되었다. 58개의 균주들(27.68)은 두 개 이상의 장내독소 유전자가 증폭되었다. 가장 많이 나타난 독소 조합군은 sea와 seb로 26개 균주(12.4%)에서 발견되었으며 다음으로 빈번한 조합은 sec와 tst로 14균주(6.7%)로 나타났다. 210개 중 109개의 균주는 서울 지역에서 분리된 것이었고 101개는 부산 지역에서 분리된 균이었다. 부산지역에서 장내독소 A 유전자(sea)의 발생율은 서울에서보다 두 배 더 높게 나타났다(57.1% 대 23.6%). 그러나 장내독소 c유전자(sec)와 d유전자(sed)는 서울 지역에서 각각 23.6%와 17.9%로 비슷하게 나타난 반면에 부산 지역에서는 각각 2.0% 미만으로 거의 무시할 수 있을 정도로 낮게 나타났다. 한국의 장독소 형별 검출을 외국과 비교하면 장독소A의 검출빈도가 가장 높은 것은 같으나 차순으로 빈도가 높은 것이 외국의 경우 b유전자인데 반하여 한국에서는 c유전자로 실험결과 나타났다. 또한 한국에서의 d유전자 검출빈도가 b유전자 보다 높아 주된 유행형인 a유전자를 제외한 기타 독소형의 분포는 국가간 또는 지역간에도 차가 있는 것으로 결론지을 수 있다. In this study we attempted multiplex PCR for rapid detection of genes for nuc, mecA. enterotoxin A to E and TSST-l(tst) in bacterial lysates extracted from human strains of S aureus. In 210 isolates of methicillin-resistant Staphylococcus aureus (MRSA), all strains showed both nuc gene and mecA gene positive except two strains that showed only nuc gene positive. One hundred sixty nine(80.5%) of 210 MRSA isolates tested produced one or more toxins. Other 41(19.5%) isolates did not produce any of the toxins. Enterotoxin A gene(sea) was amplified in 50.5%(n=105) of the isolates, enterotoxin B(seb) in 14.3%(n=30), enterotoxin C(sec) in 23.3%(n=49), enterotoxin D(sed) in 10.0%(n=21) and TSST-l(tst) in 12.4%(n=26). Fifty eight strains(27.6%) amplified more than two enteroxin genes. The most common combination of toxin gene was sea and seb, which was found in 26(12.4%) strains, and the next frequent combination was sec and tst in 14(6.7%) strains from 210 isolates among which 109 MRSA strains tested were isolated in Seoul area and 101 in Pusan area. The frequency rate of enterotoxin A in Pusan was twice higher than that of Seoul with 57.1% to 23.6%. But the frequency rates of enterotoxins C and D genes in Seoul area are analogous with relatively narrow margin while those rates in Pusan area were almost negligible with less than 2% each. Apparent difference of enterotoxin type distribution was also found between the countries. Beside enterotoxin A which was most predominantely found in both European countries and Korea, enterotoxin C was the subsequently prevalent type of toxin in Korea instead of enterotoxin b which was found as the second most prevalent enterotoxin in some European countries

Yarrowia lipolytica의 Multicopy Integration Vector 개발

김정윤,우문희,Dewey D.Y. Ryu 한국산업미생물학회 1995 한국미생물·생명공학회지 Vol.23 No.5

Multicopy integration vector는 복제수가 많고 non-selective한 환경조건 하에서도 매우 안정되게 유지가 되기 때문에 heterologous 유전자를 발현시키는데 매우 유용한 벡터 시스템이다. Yarrowia lipolytica의 multicopy integration vector를 개발하기 위하여 Y. lipolytica로부터 P-type rDNA를 클로닝하였다. 이 클론된 rDNA의 HindIII-BglII 절편과 promoter 지역을 포함하고 있지 않은 URA3 유전자를 pGEM1 plasmid에 삽입하여 제조한 벡터를 pMIYL-1과 pMIYL-2로 명명하였다. RDNA 절편은 벡터와 chromosomal DNA 사이에 homologous recombination을 유도하기 위한 것이며, promoterless URA3는 불완전한 표지 유전자로서 multicopy integration을 유발시키기 위한 것이다. PMIYL-1은 rDNA의 HindIII-BglII 절편내에 유일한 제한효소 자리로서 KpnI을 가지고 있고, pMIYL-2는 KpnI과 EcoRI을 가지고 있다. 이 벡터들을 Y. lipolytica에 도입한 후에 형질 전환체를 선별하여 copy 수와 안정성을 검사한 결과, 벡터의 copy 수는 5개 이하로 존재하고 non-selective 배지에서도 매우 안정하게 유지가 됨을 알 수 있었다. Multicopy integration vector is a very useful vector system in that they can be integrated into chromosomal DNA in several copies and stably maintained under non-selective conditions. To develop a multicopy integration vector system in the yeast Yarrowia lipolytica, P-type ribosomal DNA was cloned from Y. lipolytica. A HindIII-BglII fragment of the cloned rDNA and a promoterless URA3 gene were inserted into pGEM1, generating multicopy integration vectors, pMIYL-1 and pMIYL-2. The rDNA fragment is for targeted homologous recombination between the vector and the chromosomal DNA of Y. lipolytica, and the promoterless URA3 gene is a defective selection marker for inducing multicopy integration. pMIYL-1 and pMIYL-2 have an unique restriction enzyme site, KpnI, and two unique restriction enzyme sites, KpnI and EcoRI, repectively, which can be used for targeting of the vectors into the rDNA of Y. lipolytica chromosomal DNA. After transformation of the vectors into Y. lipolytica, copy number and stability were analyzed by Southern hybridization. The vectors were found to be present in less than 5 copies per cell and were stably maintained during growth in non-selective media.

EFFECT OF INTAKE PORT GEOMETRY ON THE IN-CYLINDER FLOW CHARACTERISTICS IN A HIGH SPEED D.I. DIESEL ENGINE

LEE K. H.,RYU I. D.,LEE C. S.,REITZ R. D. The Korean Society of Automotive Engineers 2005 International journal of automotive technology Vol.6 No.1

Recently, the HSDI (High Speed Direct Injection) diesel engine has been spotlighted as a next generation engine because it has a good potential for high thermal efficiency and fuel economy. This study was carried out to investigate the in-cylinder flow characteristics generated in a HSDI diesel engine with a 4-valve type cylinder head. The four kinds of cylinder head were manufactured to elucidate the effect of intake port geometry on the in-cylinder flow characteristics. The steady flow characteristics such as coefficient of flow rate $(C_{f})$, swirl ratio (Rs), and mass flow rate (m,) were measured by the steady flow test rig and the unsteady flow velocity within a cylinder was measured by PIV. In addition, the in-cylinder flow patterns were visualized by the visualization experiment and these results were compared with simulation results calculated by the commercial CFD code. The steady flow test results indicated that the mass flow rate of the cylinder head with a short distance between the two intake ports is $13\%$ more than that of the other head. However, the non-dimensional swirl ratio is decreased by approximately $15\%$. As a result of in-cylinder flow characteristics obtained by PIV and CFD calculation, we found that the swirl center was eccentric from the cylinder center and the position of swirl center was changed with crank angle. As the piston moves to near the TDC, the swirl center corresponded to the cylinder center and the velocity distribution became uniform. In addition, the results of the calculation are in good agreement with the experimental results.