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D-Amino Acid Aminotransferase 활성보유 고온성미생물의 탐색 및 분류학적 특성 연구
곽미선,이승구,정상철,서승현,이재흥,전영중,김영호,성문희 충남대학교 약학대학 의약품개발연구소 1999 藥學論文集 Vol.15 No.-
To acquire an industrially useful biocatalyst for the enzymatic synthesis and production of various D-amino acids, 1,300 thermophiles isolated from the soil of Korea were analyzed for D-amino acid aminotransferase (D-AAT) activity. The enzyme activity was found from 110 strains of isolated thermophiles revealing its wide occurrence in thermophiles. Enzyme activity and thermal stability of the D-AAT producers were compared. Finally we have selected four thermophiles as producers of potent biocatalysts for the D-amino acid production; two therrnophiles, Bacillus sp. LK-I and LK-2, having higher specific activity and two thermophiles, B. stearothermophilus KL-01 and Bacillus sp. KLS-0l, having higher thermal stability than the D-AAT producers. Taxonomic and physiological characteristics of the four isolated thermophiles were described herein.
최성우,우성훈,윤철종,곽명화,서향미,박승조 동아대학교 환경문제연구소 2000 硏究報告 Vol.23 No.1
This study has carried out the coagulation tests for tannery wastewater including high-level suspended solids and organic matters to determine the optimum pH and coagulant dosage and to characterize several coagulants for coagulation. In case of optimum pH range test, we know that multi-coagulants are not only cost-effective but also applicable from acidic pH range to alkaline pH range widely, while single-coagulant are useful in limited pH range. Removal efficiency for using of the multi-coagulants appeared more efficient than that of single-coagulant. Especially, sulfates(alum-ferric sulfate : AFS & alum-magnesium sulfate : AMS) are more effective than chlorides (alum-ferric chloride : AFC & alum-magnesium chloride AMC). In comparison of residual turbidity related to settling time between alum and alum-ferric sulfate-magnesium sulfate(AFM), it took to 40 minutes using of alum but 5 minutes using of alum-ferric sulfate-magnesium sulfate(AFM) until constant residual turbidity are reached.
Seung-Mi Kwak 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.1
Nanopowders of Al2O3 and MgO were fabricated by high energy ball milling. The rapid synthesis and sintering of nanostuctured MgAl2O4 compound were investigated by the pulsed current activated sintering process. The advantage of this process is that it allows very quick densification to near theoretical density and inhibition of grain growth. A highly dense nanostructured MgAl2O4 compound was produced with the simultaneous application of 80 MPa pressure and a pulsed current of 2800A within two minutes. The grain sizes and mechanical properties of MgAl2O4 sintered at 1320 ο C were investigated.
볼 밀링한 분말의 펄스전류활성 소결에 의한 나노구조의 지르코니아 제조와 기계적 성질
곽승미 ( Seung Mi Kwak ),박현국 ( Hyun Kuk Park ),손인진 ( In Jin Shon ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.5
The effect of high-energy ball milling on sintering, microstructure and mechanical properties of ZrO2 was investigated. The starting temperature of consolidation decreased with high-energy ball milling because the driving force for sintering, and the contact points of powders for atomic diffusion, increased. The mechanical properties (hardness and fracture toughness) and relative density of ZrO2 sintered from high-energy ball milled powder were higher than those of ZrO2 sintered from unmilled powder. A highly dense nanostructured ZrO2 was produced using high-energy ball milled powder with simultaneous application of 80 MPa pressure and pulsed output current of 2800 A within 2 min.
이승미 ( Seung Mi Lee ),( Young Mi Jung ),( Eun Saem Choi ),( Soo Heon Kwak ),( Ja Nam Koo ),( Ig Hwan Oh ),( Byoung Jae Kim ),( Sun Min Kim ),( Sang Youn Kim ),( Gyoung Min Kim ),( Sae Kyung Joo ),( Bo 대한산부인과학회 2022 대한산부인과학회 학술대회 Vol.108 No.-
BACKGROUND & AIMS: Recently, metabolic dysfunction-associated fatty liver disease (MAFLD), rather than nonalcoholic fatty liver disease (NAFLD), was proposed to better describe liver disease associated with metabolic dysfunction (MD). In this study, we attempted to investigate the impact of MAFLD on pregnancy complications. METHODS: The current study is a secondary analysis of a multicenter prospective cohort designed to examine the risk of NAFLD during pregnancy. In the first trimester, enrolled pregnant women were evaluated for hepatic steatosis by liver ultrasonography, and blood samples were collected for biochemical measurements. The study population was divided into 3 groups: no NAFLD, hepatic steatosis but without metabolic dysfunction (non-MD NAFLD), and MAFLD. The primary outcome was the subsequent development of adverse pregnancy outcomes, including gestational diabetes mellitus, pregnancy-associated hypertension, preterm birth, and fetal growth abnormalities. RESULTS: The study population consisted of 1744 pregnant women, including 1523 with no NAFLD, 43 with non-MD NAFLD, and 178 with MAFLD. The risk of subsequent development of adverse pregnancy outcomes was higher in MAFLD than in non-MD NAFLD (adjusted odds ratio, 4.03; 95% CI, 1.68-9.67), whereas the risk was not significantly different between no NAFLD and non-MD NAFLD. 3) Among women with no NAFLD, the presence of MD increased the risk of adverse pregnancy outcomes. However, women with MAFLD were at higher risk for adverse pregnancy outcomes than women with no NAFLD without MD or those with no NAFLD with MD. CONCLUSIONS: In pregnant women, MAFLD may be associated with an increased risk of subsequent adverse pregnancy outcomes.
Kwak, Sang-Won,Moon, Young-Mi,Yoo, Yeon-Jee,Baek, Seung-Ho,Lee, WooCheol,Kim, Hyeon-Cheol The Korean Academy of Conservative Dentistry 2014 Restorative Dentistry & Endodontics Vol.39 No.4
Objectives: The purpose of this study was to compare the cutting efficiency of a newly developed microprojection tip and a diamond-coated tip under two different engine powers. Materials and Methods: The apical 3 mm of each root was resected, and root-end preparation was performed with upward and downward pressure using one of the ultrasonic tips, KIS-1D (Obtura Spartan) or JT-5B (B&L Biotech Ltd.). The ultrasonic engine was set to power-1 or -4. Forty teeth were randomly divided into four groups: K1 (KIS-1D / Power-1), J1 (JT-5B / Power-1), K4 (KIS-1D / Power-4), and J4 (JT-5B / Power-4). The total time required for root-end preparation was recorded. All teeth were resected and the apical parts were evaluated for the number and length of cracks using a confocal scanning micrscope. The size of the root-end cavity and the width of the remaining dentin were recorded. The data were statistically analyzed using two-way analysis of variance and a Mann-Whitney test. Results: There was no significant difference in the time required between the instrument groups, but the power-4 groups showed reduced preparation time for both instrument groups (p < 0.05). The K4 and J4 groups with a power-4 showed a significantly higher crack formation and a longer crack irrespective of the instruments. There was no significant difference in the remaining dentin thickness or any of the parameters after preparation. Conclusions: Ultrasonic tips with microprojections would be an option to substitute for the conventional ultrasonic tips with a diamond coating with the same clinical efficiency.
The Expression of Hyperacute Immune Rejection Genes in the Skin derived from Transgenic Pigs
Seung-Chan Lee,In-Sul Hwang,Tae-Uk Kwak,Mi-Ryung Park,Keon Bong Oh,Sun-A Ock,Jae-Seok Woo,Jeong-Woong Lee,Gi-SunIm,Seongsoo Hwang 한국동물생명공학회(구 한국동물번식학회) 2017 발생공학 국제심포지엄 및 학술대회 Vol.2017 No.10
Porcine skin and preserved cadaver skin are used for temporary wound coverage, but 1 to 2 weeks after grafting, these tissues undergo immune-mediated rejection. To avoid such antigenicity, different types of acellular dermal matrix (ADM) have been studied. The generation of pigs lacking the α-1,3 galactosyl transferase (GT—/—) expressed by α-Gal epitope (Galα1,3Galα 1,4GlcNAc-R) has minimized hyperacute rejection. This study was performed to investigate the expression of α-Gal epitope in the skin derived from GT—/— transgenic pigs. The skin (7/1,000 inches) was obtained by dermatome (Zimmer®Electric Dermatome) from around one month old of wild type (WT), GT—/—,and GT-MCP/-MCP piglets, respectively. The skins treated with decellularization were fixed, dehydrated, cleaned, and embedded. It was confirmed that α-Gal epitope was not detected in the skins from TG pigs stained with BS-IB4 lectin antibody, but in WT skin. To analyze the characteristics of immune response genes in ADM skins, the tissue sections were stained with anti-HLAE and anti-MHC I antibodies. Decellularized skins of GT—/—and GT-MCP/-MCP were not stained in both HLAE and MHC I, but the both immune response genes were strongly expressed in epidermis and dermis, respectively. Taken together, it can be postulated that ADM skin originated from GT KO pigs may be used as a source of xenoskingraft. Further studies are needed to evaluate the functions of the ADM skins of GT—/— and GT-MCP/-MCP pigs after xenograft.
Current Perspectives regarding Stem Cell-Based Therapy for Alzheimer's Disease
Kwak, Kyeong-Ah,Lee, Seung-Pyo,Yang, Jin-Young,Park, Young-Seok Hindawi 2018 Stem cells international Vol.2018 No.-
<P>Alzheimer's disease (AD), a progressive neurodegenerative disorder featuring memory loss and cognitive impairment, is caused by synaptic failure and the excessive accumulation of misfolded proteins. Many unsuccessful attempts have been made to develop new small molecules or antibodies to intervene in the disease's pathogenesis. Stem cell-based therapies cast a new hope for AD treatment as a replacement or regeneration strategy. The results from recent preclinical studies regarding stem cell-based therapies are promising. Human clinical trials are now underway. However, a number of questions remain to be answered prior to safe and effective clinical translation. This review explores the pathophysiology of AD and summarizes the relevant stem cell research according to cell type. We also briefly summarize related clinical trials. Finally, future perspectives are discussed with regard to their clinical applications.</P>
(Seung Goo Lee),(Seung Pyo Hong),(Mi Sun Kwak),(Nobuyoshi Esaki),(Moon Hee Sung) 생화학분자생물학회 1999 BMB Reports Vol.32 No.5
Tyrosine phenol-lyase of thermophilic Symbiobacterium sp. SC-1, which is obligately and symbiotically dependent on thermophilic Bacillus sp. SK-1, was purified and characterized. The enzyme is composed of four identical subunits and contains approximately 1 ㏖ of pyridoxal 5`-phosphate (PLP) per ㏖ subunit as a cofactor. The enzyme showed absorption maxima at 330 and 420 nm, and lost this absorption profile by treatment with phenylhydrazine. The apparent dissociation constant, K`_D, for PLP was determined with the apoenzyme to be about 1.2 μM. The isoelectric point was 4.9. The optimal temperature and pH for the α,β-elimination of z-tyrosine were found to be 80℃ and pH 8.0, respectively. The substrate specificity of the enzyme was very broad: L-amino acids including L-tyrosine, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), L-cysteine, L-serine, S-methyl-L-cysteine, β-chloro-L-alanine, and S-(o-nitrophenyl)-L-cysteine all served as substrates. D-Tyrosine and D-serine were also decomposed into pyruvic acid and ammonia at rates of 7 % and 31 % relative to their corresponding L-enantiomers, respectively. D-Alanine, which was inert as a substrate in α,β-elimination, was the only v-amino acid racemized by the enzyme. The K_m values for L-tyrosine, z-DOPA, S-(o-nitrophenyl)-L-cysteine, β-chloro-L-alanine, and S-methyl-L-cysteine were 0.19, 9.9, 0.36, 12, and 5.5 mM, respectively.