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Stress Tolerance and Virulence-Related Roles of Lipopolysaccharide in Burkholderia glumae
Chaeyeong Lee,Mohamed Mannaa,Namgyu Kim,Juyun Kim,Yeounju Choi,Soo Hyun Kim,Boknam Jung,Hyun-Hee Lee,Jungkwan Lee,Young-Su Seo 한국식물병리학회 2019 Plant Pathology Journal Vol.35 No.5
The lipopolysaccharide (LPS) composed of lipid A, core, and O-antigen is the fundamental constituent of the outer membrane in gram-negative bacteria. This study was conducted to investigate the roles of LPS in Burkholderia glumae, the phytopathogen causing bacterial panicle blight and seedling rot in rice. To study the roles of the core oligosaccharide (OS) and the Oantigen region, mutant strains targeting the waaC and the wbiFGHI genes were generated. The LPS profile was greatly affected by disruption of the waaC gene and slight reductions were observed in the O-antigen region following wbiFGHI deletions. The results indicated that disruption in the core OS biosynthesis-related gene, waaC, was associated with increased sensitivity to environmental stress conditions including acidic, osmotic, saline, and detergent stress, and to polymyxin B. Moreover, significant impairment in the swimming and swarming motility and attenuation of bacterial virulence to rice were also observed in the waaC-defective mutant. The motility and virulence of O-antigen mutants defective in any gene of the wbiFGHI operon, were not significantly different from the wild-type except in slight decrease in swimming and swarming motility with wbiH deletion. Altogether, the results of present study indicated that the LPS, particularly the core OS region, is required for tolerance to environmental stress and full virulence in B. glumae. To our knowledge, this is the first functional study of LPS in a plant pathogenic Burkholderia sp. and presents a step forward toward full understanding of B. glumae pathogenesis.
Stress Tolerance and Virulence-Related Roles of Lipopolysaccharide in Burkholderia glumae
Lee, Chaeyeong,Mannaa, Mohamed,Kim, Namgyu,Kim, Juyun,Choi, Yeounju,Kim, Soo Hyun,Jung, Boknam,Lee, Hyun-Hee,Lee, Jungkwan,Seo, Young-Su The Korean Society of Plant Pathology 2019 Plant Pathology Journal Vol.35 No.5
The lipopolysaccharide (LPS) composed of lipid A, core, and O-antigen is the fundamental constituent of the outer membrane in gram-negative bacteria. This study was conducted to investigate the roles of LPS in Burkholderia glumae, the phytopathogen causing bacterial panicle blight and seedling rot in rice. To study the roles of the core oligosaccharide (OS) and the O-antigen region, mutant strains targeting the waaC and the wbiFGHI genes were generated. The LPS profile was greatly affected by disruption of the waaC gene and slight reductions were observed in the O-antigen region following wbiFGHI deletions. The results indicated that disruption in the core OS biosynthesis-related gene, waaC, was associated with increased sensitivity to environmental stress conditions including acidic, osmotic, saline, and detergent stress, and to polymyxin B. Moreover, significant impairment in the swimming and swarming motility and attenuation of bacterial virulence to rice were also observed in the waaC-defective mutant. The motility and virulence of O-antigen mutants defective in any gene of the wbiFGHI operon, were not significantly different from the wild-type except in slight decrease in swimming and swarming motility with wbiH deletion. Altogether, the results of present study indicated that the LPS, particularly the core OS region, is required for tolerance to environmental stress and full virulence in B. glumae. To our knowledge, this is the first functional study of LPS in a plant pathogenic Burkholderia sp. and presents a step forward toward full understanding of B. glumae pathogenesis.
Secondary Neutron Dose Measurement for Proton Line Scanning Therapy
Lee, Chaeyeong,Lee, Sangmin,Chung, Kwangzoo,Han, Youngyih,Chung, Yong Hyun,Kim, Jin Sung Korean Society of Medical Physics 2016 의학물리 Vol.27 No.3
Proton therapy is increasingly being actively used in the treatment of cancer. In contrast to photons, protons have the potential advantage of delivering higher doses to the cancerous tissue and lower doses to the surrounding normal tissue. However, a range shifter is needed to degrade the beam energy in order to apply the pencil beam scanning technique to tumors located close to the minimum range. The secondary neutrons are produced in the beam path including within the patient's body as a result of nuclear interactions. Therefore, unintended side effects may possibly occur. The research related to the secondary neutrons generated during proton therapy has been presented in a variety of studies worldwide, since 2007. In this study, we measured the magnitude of the secondary neutron dose depending on the location of the detector and the use of a range shifter at the beam nozzle of the proton scanning mode, which was recently installed. In addition, the production of secondary neutrons was measured and estimated as a function of the distance between the isocenter and detector. The neutron dose was measured using WENDI-II (Wide Energy Neutron Detection Instruments) and a Plastic Water phantom; a Zebra dosimeter and 4-cm-thick range shifter were also employed as a phantom. In conclusion, we need to consider the secondary neutron dose at proton scanning facilities to employ the range shifter reasonably and effectively.
ATM 기반 상호 연결망 전송 프로토콜의 설계 및 소켓 기반 응용 프로그램을 위한 ATM 상호 연결망 DLPI 드라이버의 설계
이채영(Chaeyeong Lee),강종희(Jonghee Kang),신현식(Heonshik Shin) 한국정보과학회 1997 한국정보과학회 학술발표논문집 Vol.24 No.2Ⅲ
근거리 및 원거리 네트워크의 성능을 향상시키는 연구 결과 새로운 매체들과 전송 방이 등장하게 되었으며, 이러한 결과를 바탕으로 병렬 컴퓨터의 상호 연결망에 적용하는 연구가 진행되고 있다. 이중에서 ATM(Asynchronous Transfer Mode)은 대량의 데이타를 고속으로 전송하는데 적합한 성능을 지녔다. 본 논문에서는 병렬 컴퓨터의 상호 결망의 요구조건을 분석하고, ATM을 병렬 컴퓨터의 상호 연결망으로 사용하는 두 가지 기법에 대한 설계를 기술한다. 한 가지 방법은 ATM에 적합하도록 새로운 프로토콜을 설계하는 것이고, 다른 방법은 소켓 기반 응용 프로그램을 고려하여 데이타 링크 레벨에서 ATM을 사용하도록 하는 방법이다. 두 기법간의 접근 방법은 성능의 향상에 중점을 둔 것인지 여부와 기존 응용프로그램의 이식 가능성을 높이느냐의 여부에서 차이점을 갖고 있다.
Dong-Hoon Lee,Chanwoo Park,Cheol-Ha Baek,Chaeyeong Lee,Seung-Jae Lee,Hankyeol Song,Yong Hyun Chung Professional Technical Group on Nuclear Science 2017 IEEE transactions on nuclear science Vol. No.
<P>Gamma-ray computed tomography (CT) has widely been used to inspect cracks, obstructions, and fluid flow in pipes. Previous studies have shown that the inspection accuracy is limited when materials in the pipe have a similar density. To overcome this drawback, we investigated a method to discriminate small density differences using a dual-energy gamma-ray CT. In this paper, the performance of a gamma-ray CT system was simulated using Geant4 Application for Tomographic Emission with three types of sources (Am-241, Co-57, and Cs-137). A polyvinyl chloride (PVC) pipe containing oil and sludge was modeled as a phantom. Sparsely acquired data were reconstructed using filtered back-projection and iterative total variation (TV) denoising algorithms. Each material discrimination procedure was performed with a postreconstruction technique. Our results clearly showed that the gamma-ray CT imaging with Am-241 and Co-57 sources and the TV denoising reconstruction algorithm can be used to inspect the internal structures based on discriminated images. The calculated areas of discriminated oil and sludge were within an error margin of 2% (oil: 78.4% and sludge: 21.6%) compared with the simulated phantom (oil: 80% and sludge: 20%). For both gamma sources, the calculated contrast-to-noise ratio (CNR) values with the TV denoising algorithm were the highest values for all structures (Am-241/Co-57: 18.03/28.95 for oil versus sludge, 41.67/31.53 for oil versus PVC pipe, and 23.64/31.53 for sludge versus PVC pipe). The feasibility of our approach and results indicates it usefulness for industrial fields that require structural inspections.</P>
Seung-Jae Lee,Chaeyeong Lee,정용현,강지훈,Cheol-Ha Baek 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.12
We designed a depth-of-interaction (DOI) positron emission tomography detector by applying a simple light-spreading method in a single-layer crystal array with a single-ended photosensor. By configuring different reflector patterns along the depth of the crystal, we were able to alter the light distribution of the gamma interaction at each depth. To evaluate the characteristics of the new DOI detector, we simulated the optical photon transport in the crystal array by using DETECT2000. Three different arrays comprising triangular-, square-, and hexagonal-shaped crystals were modeled. The 511-keV gamma-ray interactions were generated for all depths, and flood images were acquired. We confirmed that DOI layers could be distinguished in the obtained images and that the number of DOI layers depends on the number of sides of the polygonal crystals.