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국내에서 분리된 Vancomycin 내성 장구균에 대한 분자역학적 연구
김수정,이남용,배직현,이경원,이위교,김의종,최명식,백경란,김성민,송재훈 대한감염학회 1998 감염 Vol.30 No.1
목 적 : 장구균은 병원 감염의 원인균으로서 최근 그 빈도와 중요성이 증가하고 있다. 특히 vancomycin에 내성을 보이는 장구균(VRE)은 효과적인 치료약제가 드물고, 그 내성 유전자가 vancomycin에 감수성을 보이는 다른 장구균이나 그람양성 구균에 전달될 수 있어 임상적인 중요도가 더욱 크다. 본 연구에서는 국내 5개 병원에서 분리된 VRE 균주의 표현형과 유전형을 결정하고, 분자역학적 방법을 이용하여 유전적 연관성 여부를 밝히고자 하였다. 방 법 : 각 병원에서 수집된 균주는 환자의 임상 검체에서 또는 VRE 집락화에 대한 선별검사에서 분리된 균주였다. 이들을 대상으로 vancomycin과 teicoplanin의 MIC를 측정하여 표현형을 결정하였으며, PCR로 vancomycin 내성 유전자를 증폭하여 유전형을 결정하였다. 또한 이들중 vanA와 vanB 유전자를 갖는 균주들을 대상으로 플라스미드 분석과 PFGE를 시행하였다. 결 과 : VRE로 최종 동정된 균주들은 42균주(E. faecium 21주, E. faecalis 6주, E. avium 2주, E. casseliflavus 13주)였으며, 항균제 감수성 양상으로 결정한 표현형은 VanA, VanB, VanC형이 각각 14주(33%), 7주(17%), 21주(50%)였다. PCR로 결정한 유전형은 vanA 12주(E. faecium), vanC 16주 였으며, 이중 VanA의 표현형을 보인 E. faecium 2주가 VanB의 유전형으로 판명된 것을 제외하면 표현형과 유전형은 모두 일치하였다. 플라스미드 분석과 PFGE 결과, 병원내 동일 균주의 전파 가능성이 5개 병원중 3병원에서 증명되었다. 결 론 : 국내 병원에서도 vancomycin 내성 유전자를 갖는 VRE가 다수 분리되고 있음을 확인할 수 있었으며, 연구 결과 일부 병원에서 내성균주의 병원내 전파 가능성을 시사하였다. 아직까지 국내에서 VRE로 인한 감여보고는 적지만 곧 임상적으로 문제가 될 것으로 판단되며, 따러서 내성균의 발생이나 확산을 억제하기 위한 노력과 감시가 필요할 것으로 생각된다. Background : Enterococci have emerged in recent years as a frequent cause of life-threatening nosocomial infections. The emergence of vancomycin-resistant enterococci(VRE) presents as an increasingly important problem particularly in the treatment and the potential dissemination of vancomycin-resistance. The purpose of this study is to determine the phenotypes and genotypes of VRE isolated from five hospitals and to study the genetic relatedness among them. Methods : Antimicrobial susceptibility patterns and amplification of vancomycin resistance genes were used for phenotyping and genotyping of 42 VRE isolates respectively. For 21 isolates with vanA or vanB gene, plasmid profiles and pulsed field gel electrophoresis(PFGE) patterns were analyzed for molecular epidemiologic study. Results : Out of 42 isolates, 21 were identified as E. faecium, 6 as E. faecalis, 2 as E. avium, and 13 as E. casseliflavus. Phenotyping showed 14 isolates as VanA(33%), 7 as VanB(17%) and 21 as VanC(50%). Genotyping resulted in 12 isolates as VanV(5 of E. faecalis and 7 of e. faecium) and 9 as VanB(all E. faecium). Genotyping results were concordant with phenotyping results except for the two E. faecium isolates of VanA which had VanB genotype. Intrahospital spread of the same strains was proven in three hospitals by plasmid profiles and PFGE analysis. Conclusion : The study demonstrated a considerable number of VRE isolates in Korea and intrahospital spread proven by molecular epidemiologic methods. Although VRE infection has been considered very are in Korea, practical guidelines including restriction of vancomycin usage and surveillance, are warranted to prevent infection and dissemination of VRE.
연약점토층 위에서 선행하중의 제거-재압축에 따른 점토지반의 거동
정성교,이남기,조기영,김문규 동아대학교 건설기술연구소 1997 硏究報告 Vol.21 No.2
Little has been known about the characteristics of short-term and long-term resettlements on soft clay, such as elastic behaviour and secondary compression due to partial removal of preloading. In this study, different types of oedometer tests on a natural soft clay were peformed for examining such characteristics. As the results of the experiments, the characteristics of short-term and long-term resettlements such as rebound ratio, resettlement point and rate of secondary compression depends on the overconsolidation ratio(OCR) and preloading time. It is showed that resettlement point increased with increasing preloading, but such is not for rebound ratio and rate of secondary compression. This reason would be due to rearrangement of clay particles. And rebound ratio and resettlement point increased with increasing the OCR, but such is not for rate of secondary compression. The correlations between them is showed all the linear relations in a semi-logarithem or log-log plots, and then can be used for settlement prediction in field, as well its results can be compared with those of conventional method. from the comparative results of settlement prediction, it is found as follows : The amount of rebound due to partial removal of preloading and resettlement due to reloading are similar for both methods. But the amount of secondary compression due to partial removal of preloading by this correlation is rather overestimated than that of conventional method, because it would be underestimated the duration of primary consolidation. And for different loading histories, the compression is affected by strain rate(ε_(v)), that is, the compression increases with decreasing strain rate.
Boundary Migration Induced Plasticity during Recrystallization and Growth under Applied Stress
Kim, Se Jong,Cho, Yi Gil,Suh, Dong Woo,Kim, Sung Joon,Kim, Gyo Sung,Han, Heung Nam Trans Tech Publications, Ltd. 2007 Materials science forum Vol.558 No.-
<P>In general, plastic strain occurs over a certain stress, called yield stress. However, it has been reported that the permanent strain could happen during boundary migrating even under the extremely slight externally applied stress. In this study, we performed dilatometry experiments under the various compressive stresses and measured the amount of recrystallization and growth induced permanent strain. A new empirical constitutive equation was suggested to describe the recrystallization and growth induced plasticity. This equation was verified by comparing the calculated values with dilatometric experimental data under the various compressive stresses.</P>
Gyo-Nam Kim,Hae-Dong Jang 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.5
This study was carried out to investigate the effect of enzyme treatment with β-glucosidase on antioxidant capacity of the mulberry leaf extract (MLE) using oxygen radical absorbance capacity (ORAC) and cellular antioxidant capacity (CAC) assay. The MLE was prepared by autoclaving at 121℃ for 15 min and treated with β-glucosidase for 9 hr. High pressure liquid chromatography (HPLC) analysis showed that only qercetin-3-β-D-glucose (QT-G) among quercetin (QT) glycosides of MLE, including QT-G, quercetin-3-O-glucose-6"-acetate (QT-GA), and rutin (RT), was converted into QT by 3 hr treatment with β-glucosidase. The in vitro peroxyl radical- and hydroxyl radical scavenging capacity significantly increased after the enzyme treatment using β-glucosidase for 6 and 9 hr,respectively. The metal chelating activity increased after the enzyme treatment using β-glucosidase for 3 hr. The intracellular antioxidant capacity of MLE to protect AAPH- and Cu2+-induced oxidative stress in HepG2 cells significantly increased after the enzyme treatment using β-glucosidase for 3 and 6 hr, respectively, indicating that QT may be released from QT-G by β-glucosidase and penetrate into cell membrane so that it can contribute to the intracellular antioxidant capacity of MLE.