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류마티스 관절염의 활막 섬유모세포에서 Hypoxia/reoxygenation에 의한 종양 억제 인자 PTEN 발현의 조절
이학용 ( Hak Yong Lee ),류완희 ( Wan Hee Yoo ) 대한류마티스학회 2004 대한류마티스학회지 Vol.11 No.4
Objective: The lack of phosphatase and tensin homolgue deleted on chromosome ten (PTEN) expression was described in rheumatoid synovial tissues and synovial fibroblasts, but exact cause of that in RA is not well known. Hypoxic conditions are thought to exist in inflamed arthritic synovium and therefore, this study was designed to investigate the effects of hypoxia/reoxygenation on the expression of PTEN in synovial fibroblasts of rheumatoid arthritis. Methods: Synovial fibroblasts were isolated from synovial tissues of patients suffering from RA and hypoxic culture was performed by incubating cells in 5% CO2 incubator held at 3% oxygen by the addition of nitrogen gas for 24 hours. Then synovial fibroblasts were cultured for 10 min under normoxic condition for reoxygenation. To know the expression of PTEN and phosphorylated Akt (p-Akt) in synovial fibroblasts, Western blotting analysis was performed. The expression of PIP3 kinase and PTEN was analyzed by immunocytochemical staining. Results: There were less PTEN expression in rheumatoid synovial fibroblasts than that of healthy controls. Hypoxic/reoxygenation stimuli induced down-regulation of PTEN expression in the rheumatoid synovial fibroblasts. In contrast, the expression of PIP3 and p-Akt was increased after stimulation with hypoxia/reoxygenation. Conclusion: These studies suggest that hypoxia/reoxygenation could cause the reduced expression of PTEN in rheumatoid synovial fibroblasts and thus it might thereby contribute to the invasive behaviour of rheumatoid synovial fibroblasts by maintaining their aggressive phenotype in RA.
위성 DMB 중계기용 Cavity-Backed슬롯 배열 안테나
정희철,이학용,정병운,강기조,박면주,이병제,Jung Hee-Chul,Lee Hak-Yong,Jung Byungwoon,Kang Gi-Cho,Park Myun-Joo,Lee Byungje 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.4
This paper presents analysis of a slot array antenna having a low side lobe level and high front-to-back ratio for a repeater system of a satellite DMB(Digital Multimedia Broadcasting) service. Antennas for this repeater system require a high gain and enough isolation to reduce interferences between signals in system. Therefore, it is necessary to suppress a side lobe level and to increase front-to-back ratio. Unlike a structure 134 by lossy microstrip lines, in this work a single cavity-backed slot antenna array using a single waveguide feed is proposed to obtain the reliability for high power handling and high radiation efficiency. The side lobe level and front-to-back ratio are enhanced with tapered array technique and an optimized vertical reflector. The measured side lobe levels in H- and E-plane are under $-33.24\;\cal{dB}$ and $-35.78\;\cal{dB}$, respectively. The front-to-back ratio over $37.84\;\cal{dB}$, and the peak gain of over $17\;\cal{dBi}$ are measured.
조용광 ( Yong Kwang Cho ),김영우 ( Yeong Woo Kim ),이학용 ( Hak Yong Lee ),박상보 ( Sang Bo Park ),박찬영 ( Chan Young Park ),이원기 ( Won Ki Lee ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.1
Sustainable and eco-friendly polymers, natural polymers, bio-based polymers, and degradable polyesters, are of growing interest because of environmental concerns associated with waste plastics and emissions of carbon dioxide from preparation of petroleum-based polymers. Degradable polymers, poly(butylene adipate-co-terephthalate) (PBAT), poly(propylene carbonate) (PPC), and poly(L-lactic acid) (PLLA), are related to reduction of carbon dioxide in processing. To improve a weak mechanical property of a degradable polymer, a blending method is widely used. This study was forced on the component separation of degradable polymer blends for effective recycling. The melt-mixed blend films in a specific solvent were separated by two layers. Each layer was analysed by FT-IR, DSC, and contact angle measurements. The results showed that each component in the PPC/PLLA and PPC/PBAT blends was successfully separated by a solvent.