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김대영(Dae Young Kim),김정민(Jung Min Kim),김헌영(Heon Young Kim),송종호(Jong Ho Song),김관회(Koan Hoi Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The welding point has been represented by rigid body element or link element in finite element analysis and simple failure criteria have been used for failure after large deformation. However, since the failure model of link element is removed at the highest loading point, it cannot support the load after the failure of welding point. Since this affects the energy absorbing characteristics of whole model in structural deformation, it became the main reason for the problem of analysis. Therefore, this paper simulated the failure characteristics of base metal of welding part by applying the EWK failure model and tried to predict the energy absorbing characteristics of base metal after failure, and verified by comparing the test and analysis. In order to express the behavior and failure of material, tensile tests and EWK tests(R notch type, U notch type, R parameter type) were performed. Also, we tried to predict the occurrence of tearing of base metal and load characteristics considering the welding part by comparing with the test result applying the EWK failure model for typical welding specimens(cross type, T type, Ⅰ type).
Biological Activity of Tumor Necrosis Factor-α Secreted from Smooth Muscle Cell Overexpressing FADD
김선미,이경아,김관회,Kim, Sun-Mi,Lee, Kyeong-Ah,Kim, Koan-Hoi Korean Society of Life Science 2007 생명과학회지 Vol.17 No.1
세포 배양액에 tetracycline이 없는 경우 FADD를 발현하면서 사멸하는 평활근세포 (FADD-SMC)에서 분비하는 $TNF-\alpha$의 활성을 조사하였다. 배양액에 tetracycline이 없는 경우 FADD-SMC는 약 1000 pg/ml의 $TNF-\alpha$를 분비하였다. $TNF-\alpha$를 포함하는 배양액을 분리하고, 이 배양액을 정상세포에 처리한 결과 인산화한 p38 MAPK와 nuclear, factor, kappa B (NF-kB)의 활성이 증가하였다. 또한 이 배양액을 L929 세포에 처리하는 경우 세포독성이 발생하였다. NF-kB, p38 MAPK 그리고 L929 세포에 대찬 효과는 배양액에서 suluble TNF receptor를 이용하여 $TNF-\alpha$를 제거하는 경우 감소하였다. This study investigated biological activity of tumor necrosis factor $(TNF)-\alpha$ secreted from smooth muscle cell (SMC) destined for death by expressing Fas associated death domain containing protein (FADD) (FADD-SMC) when the cells are grown without tetracycline in culture medium. In the absence of tetracycline the FADD-SMC secreted approximately 1000 pg/ml $TNF-\alpha$, whereas hardly detectable amount of the cytokine existed in the presence of tetracycline. The culture medium collected from the FADD-SMC grown in the absence of tetracycline increased phosphorylated form of p38 MAPK and up-regulated nuclear factor kappa B (NF-kB). The medium collected without tetracycline also caused death of L929 cells. Depletion of $TNF-\alpha$ with the soluble TNF receptor (sTNFR) inhibited the phosphorylation of p38 MAPK, the up-regulation of NF-kB activity and the death activity of the medium collected from FADD-SMC in the absence of tetracycline. These results indicate that $TNF-\alpha$ secreted from SMC undergoing death is biologically active and can affect cellular function.
Up-regulation of Matrix Metalloproteinase-9 in Smooth Muscle Cell Undergoing Death
이경아,김선미,김관회,Lee, Kyeong-Ah,Kim, Sun-Mi,Kim, Koan-Hoi Korean Society of Life Science 2006 생명과학회지 Vol.16 No.7
배지에 tetracycline이 없으면 사멸하는 평활근세포 (FADD-SMC)를 이용하여 metalloproteinase (MMP)와 사멸세포의 상관관계를 조사하였다. FADD-SMC를 tetracycline이 없는 배지에서 배양하는 경우 핵이 조각으로 잘라졌고 인산화한 p38과 ERK가 증가하고 MMP-9의 발현과 활성이 증가한 반면, cyclin D와 cyclin D의 발현은 감소하였다. 그리고 죽는 FADD-SMC에서 MMP-9의 발현은 immunofluorescen로 재확인하였다. MMP-9의 증가는 MAPK 억제제인 PD098059와 p38 MAPK 억제제인 SB203S80에 의하여 감소하였다. 그리고 MMP 억제제인 BB94는 FADD-SMC의 사멸을 감소시켰다. This study investigated whether matrix metalloproteinases (MMPs) can be modified in apoptotic smooth muscle cell (SMC) using the SMC that undergoes apoptotic death by expressing Fas-associated death domain containing protein (FADD) when they are grown without tetracycline in culture medium. In the absence of tetracycline, FADD-SMC lost adherence and showed the fragmentation of the nuclei. In proportion to duration of tetracycline removal, phosphorylated form of p38 MAPK and of ERK increased, whereas phosphorylation of protein kinase B (PKB) was not changed very much in response to tetracycline The levels of cyclin A and cyclin D were also decreased in a time dependent manner. Up-regulation of MMP-9 expression and activity was observed when the SMC were grown without tetracycline. Immunoreactivity of MMP-9 was detected from both attached and floating FADD-SMCs grown without tetracycline. An inhibitor of MAPK kinase, PD098059, and an inhibitor of p38 MAPK, SB203580, inhibited the up-regulation of MMP-9. Treatment of the SMC with a synthetic MMP inhibitor, BB94, attenuated death occurring in the absence of tetracycline. These results indicate that SMC undergoing death is able to up-regulate MMP-9 and that the enzyme can affect cell viability.