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        검색결과 30

        1.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper develops a flow control block for a hydraulic system of a tunnel boring machine. The flow control block is a necessary component to ensure stability in the operation of the hydraulic system. In order to know the pressure distribution of the flow control block, the flow analysis was performed using the ANSYS-CFX. It was confirmed that the pressure and flow rate were normally supplied to the hydraulic system even if one of the four ports of the flow control block was not operated. In order to evaluate the structural stability of the flow control block, structural analysis was performed using the ANSYS WORKBENCH. As a result, the safety factor of the flow control block is 1.54 and the structural stability is secured.
        4,000원
        3.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To develop a high pressure main drive hydraulic cylinder for concrete pumping car, it is essential to accurately predict the internal flow structure of the hydraulic cylinder and ensure structural stability. Therefore, in this study structural and buckling analysis were essentially used for safe design. From analysis results, the maximum equivalent stress occurred when the cylinder thickness was 15 mm and the hydraulic cylinder was deemed to be structurally safe. The buckling analysis of the hydraulic cylinder assembly showed that the critical load factor was from 1.3732 to 12.021 and the critical force factor in the entire area was not observed because the critical load factor was greater than 1. The average flow rate of cylinder was uniformly distributed and the flow rate error for the inlet and outlet port could be found to be approximately identical to that of 2 %.
        4,000원
        13.
        2012.06 구독 인증기관·개인회원 무료
        Cordycepin, a specific polyadenylation inhibitor, is the main functional component in Cordyceps militaris that is one of the top three renowned traditional Chinese medicines. In this study, we performed in vitro experiments to investigate the anti-invasive and anti-metastatic activities of cordycepin using human prostate carcinoma LNCaP cells. Cordycepin were administered and their effects on LPS-induced cell migration and invasion by wound healing migration assay, measurement of TER and In vitro invasiveness assay. Within the concentrations which were not cytotoxic effects, cordycepin caused a concentration-dependent suppression of LPS-induced cell migration and invasion. The anti-invasive activity of cordycepin was also found to be associated with increased tightness of the TJ, which was confirmed by an increase in TER. The activity of MMP-2 in LNCaP cells was dose-dependently inhibited by treatment with cordycepin, and this was also correlated with a decrease in expression of its mRNA and proteins, and up-regulation of TIMPs expression. Additionally, cordycepin repressed the LPS-induced NF-kB activation and phosphorylation of PI3K/AKT. Taken together, these findings suggest that cordycepin inhibited LPS-induced migration and invasion of LNCaP cells by down-regulating the expression and activity of MMP-2, and the possible targets may be NF-kB and PI3K/AKT.
        14.
        2010.12 KCI 등재 구독 인증기관·개인회원 무료
        [Background] Cordyceps militaris is a traditional popular mushroom, produces an important bioactive compound Cordycepin (3’-deoxyadenosine) used for the tonic and medicinal purpose in eastern Asia. Cordycepin is reported to possess many pharmacological activities including immunologically stimulating, anti-tumor, anti-virus, and anti-infection effects. [Methods] Growth inhibition of human leukemia cells was assessed by MTT assays. The determination of apoptotic cell death was performed by flow cytometry analysis, agarose gel electrophoresis and DAPI fluorescent staining methods. The apoptotic-regulated gene markers in both death receptor- and mitochondria-mediated apoptotic pathways were detected by RT-PCR and Western blot analysis etc. [Results] It was found that inhibition of cell proliferation was observed for human leukemia U937 and THP-1 cells treated with cordycepin in a dose-dependent manner. Cordycepin induced morphological change and apoptotic cell death such as formation of apoptotic bodies, DNA fragmentation and increased populations of apoptotic-sub G1 phase. Apoptosis of U937 and THP-1 cells by cordycepin was associated with a down-regulation of anti-apoptotic Bcl-2 and inhibitor of apoptosis proteins (IAPs) expression. Cordycepin treatment induced the proteolytic activation of caspase-3, caspase-8 and caspase-9, and a concomitant inhibition of poly(ADP-ribose) polymerase (PARP), β-catenin and phospholipase (PLC)-γ1 protein. Conclusions: Our results indicated that the apoptotic processes caused by cordycepin are mediated by the regulation of the Bcl-2 and caspase family in human leukemia U937 and THP-1 cells. Our data also suggested that cordycepin may be a potential chemotherapeutic agent for the treatment of leukemia cancer patients.
        15.
        2010.12 KCI 등재 구독 인증기관·개인회원 무료
        [Background] Cordyceps militaris, a traditional medicinal mushroom, produces a component compound, cordycepin (3’-deoxyadenosine). Cordycepin has been known to have many pharmacological activities including immunological stimulating, anti-cancer, and anti-infection activities. However, the molecular mechanisms of inflammatory mediator’s activity by cordycepin remain poorly understood. In the present study, we investigat-ed the effects of cordycepin on the anti- inflammation cascades in lipopolysaccharide (LPS)-stimulated BV2 microglia cells. [Methods] Cordycepin were administered and their effects on LPS-induced pro-inflammatory mediators and MAP kinases were monitored by Western blotting and RT-PCR analysis. [Result] Cordycepin significantly inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), and pro- inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in a concentration- dependent manner without causing cytotoxicity. Also, cordycepin suppressed inducible NO, synthase (iNOS) and cyclooxygenase-2 (COX-2) expression on the mRNA and protein level. In addition, cordycepin suppressed NF-κB translocation by blocking IkappaB- α (IκB-α) degradation and inhibited the phosphorylation of Akt, ERK-1/2, JNK, and p38 kinase. Our results indicate that the inhibitory effect of cordycepin on LPS -stimulated inflammatory mediator production in BV2 microglia is associated with the suppression of the NF-κB, Akt, and MAPK signaling pathways. Conclusion: Anti-inflammatory properties of cordycepin may be useful for treating the inflammatory and deleterious effects of microglial activation in response to LPS stimulation.
        18.
        2009.06 KCI 등재 구독 인증기관·개인회원 무료
        Cordycepin (3’-deoxyadenosine) is a polyadenylation specific inhibitor, one of the components of Cordyceps militaris. It has been shown to possess many pharmacological activities including immunologically stimulating, anti-tumor, anti-virus, and anti-infection effects. However, its molecular mechanisms are poorly understood. In this study, the apoptotic effects by cordycepin were investigated in human leukemia cells. Cordycepin treatment inhibited leukemia cells growth a concentration-dependent manner by inducing apoptosis,as evidenced by morphological change and apoptotic cell death such as formation of apoptotic bodies, DNA fragmentation and increased populations of apoptoticsub G1 phase. Induction of apoptosis by cordycepin in leukemia cells were associated with modulation of Bcl-2 member and inhibitor of apoptosis (IAP) proteins expression. Cordycepin also increased ROS generation, activation of caspase-3, caspase-8, caspase-9, cleavage of poly(ADP-ribose) polymerase (PARP), -catenin and phospholipase (PLC)-1 protein. Both the this effect by cordycepin treatment were significantly inhibited by NAC, a ROS scavenger, demonstrating the important role of ROS in the observed cytotoxic effect. This results suggested that cordycepin may be a potential chemotherapeutic agent for the treatment of leukemia patients.
        19.
        2008.06 KCI 등재 구독 인증기관·개인회원 무료
        Cordyceps militarisis well known as a traditional herbal ingredient, which has been used for patients suffering from cancer in oriental medicine. In this study we have investigated the biochemical mechanisms of anti-proliferative effects by C. militarisextract(CME) in human breast cancer MDA-MB-231 cells. It was found that CME treatment induced chromatin condensation, mitochondrial energization, annexin V staining and sub-G1 phase DNAcontent. These indicators of apoptosis correlate with the mitochondrial dependent pathway, which results in the activation of caspase-3 activity. Both the cytotoxic effect by CME treatment were significantly inhibited by z-DEVD-fmk, a caspase-3 inhibitor,demonstrating the important role of caspase-3 in the observed cytotoxic effect. Cotreatment of CME and LY294002, resulted in significantly induction of apoptosis. These results indicate that caspase-3 is a key regulator of apoptosis in response to CME in human breast cancer MDAMB- 231 through downregulation of Akt, and that the C. militaris extract may therefore have therapeutic potential against human breast cancer.
        20.
        2008.06 KCI 등재 구독 인증기관·개인회원 무료
        Agaricus blazei is well known as a traditional medicinal mushroom and it has been shown to exhibit immunostimulatory and anti-cancer activity. However, the cellular and molecular mechanism of apoptosis of cancer cells is poorly understood. In this study, we have investigated whether A. blazei extract (ABE) exerts anti-proliferative and apoptotic effects on human leukemia THP-1 cells. It was found that ABE induced a time- and dose-dependent increase in leukemia cells apoptosis through caspase-3 activation and PARP cleavage. Activation of caspase- 9 induced by ABE suggested that ABE-induced signaling was mediated through a mitochondrial death pathway. In addition, we observed an elevation of ROS and a consequent loss of mitochondrial membrane potential, further suggesting that ABE-induced death signaling was mediated through a mitochondrial oxygen stress pathway. The antioxidant Nacetylcysteine, however, opposed ABE-mediated mitochondrial dysfunction, caspase activation, and apoptosis, supporting the role of ROS in the apoptotic process. We conclude that ABE induces apoptosisin human leukemia cells through a reactive oxygen species and caspase-dependent mitochondrial pathway.
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