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방사선 조사선량에 따른 백서 악하선의 caspase-3 발현양상
권기정,최용석,황의환,이상래,고광준 대한구강악안면방사선학회 2006 Imaging Science in Dentistry Vol.37 No.1
Purpose : To investigate the caspase-3 expression in the acinar and ductal cells of rat submandibular glands after the irradiation of various doses. Materials and Methods: The male Sprague-Dawley rats weighing approximately 250 gm were used for this study. The experimental group was irradiated with a single absorbed dose of 2, 5, 10, and 15 Gy on the head and neck region. The rats were sacrificed on the 1st, 3rd, 7th, 14th, 21st, and 28th day after irradiation. The specimens including the submandibular gland were sectioned and observed using histopathological and immunohistochemical methods. Results : The local destruction of the acinar and ductal cells and the karyopyknotic nuclei of the acinar cells were observed in the 2 Gy and 5 Gy irradiation groups later than in the 10 Gy and 15 Gy irradiation groups. And the expression of caspase-3 was prominent only in the ductal cells in the 2 Gy and 5 Gy irradiation groups. Conclusion : This experiment suggests that radiation-induced apoptosis in the ductal cells of rat submandibular glands was induced by a low dose radiation associated with the activation of caspase-3 and radiation-induced necrosis was induced by a high dose radiation. (Korean J Oral Maxillofac Radiol 2006; 36 : 7-15)
Mechanism of Relaxation of Rat Aorta by Scopoletin : an Active Constituent of Artemisa Capillaris
Kwon, Eui Kwang,Jin, Sang Sik,Choi, Min Ho,Hwang, Kyung Taek,Shim, Jin Chan,Hwang, Il Taek,Han, Jong Hyun 대한동의생리학회,대한동의병리학회 2002 동의생리병리학회지 Vol.16 No.2
In the present work, we examined the mechanism of vasorelaxant effect of scopoletin, an active constituent of Artemisia capillaris on rat thoracic descending aortic rings. Scopoletin induced a concentration-dependent relaxation in rat thoracic descending aortic rings pre-contracted with phenylephrine (EC_50 = 238.94±37.4 μM), while it was less effective in rat thoracic descending aortic rings precontracted with high potassium solution (KCl 30 mM). Vasorelaxation by scopoletin was significantly inhibited after endothelial removal, but recovered at high concentration. Pretreatment of rat thoracic descending aortic rings with N^G-nitro-L-arginine (100 μM), a nitric oxide synthase inhibitor, and atropine (1 μM), a muscarinic receptor antagonist, significantly inhibited scopoletin-induced relaxation of rat thoracic descending aortic rings. Neither indomethacin (3 μM), an inhibitor of cyclooxygenase, nor propranolol (1 μM), a β-adrenoceptor antagonist, modified the effect of scopoletin. The combination of N^G-nitro-L-arginine (100 μM) and miconazole (10 μM), an inhibitor of cytochrome P 450, did not modify the effect of scopoletin, when compared with pretreatment with N^G-nitro-L-arginine (100 μM) alone. Vasorelaxant effect of scopoletin was inverted by pretreatment with diltiazem (10 μM), a Ca^2+-channel blocker, at low concentration, while restored at high concentration. Apamin (K_Ca-channel blocker, 1 μM), 4-aminopyridine (4-AP, K_V-channel blocker, 1 mM), and tetrodotoxin (TTX, Na^+-channel blocker 1 μM ) potentiated the vasorelaxant effect of scopoletin, but glibenclamide (K_ATP-channel blocker, 10 μM), tetraetylammonium (TEA, non-selective K-channel blocker, 10 mM) did not affect the relaxation of scopoletin. Free radical scavengers (TEMPO, catalase, mannitol) did not modify vascular tone. These results suggest that nitric oxide, Ca^2+- channels play a role in endothelium-dependent relaxations to scopoletin in rat aortas, that apamin, 4-AP, TTX but not glibenclamide, TEA potentiated relaxation to scopoletin mediated by these channels, and that free radicals do not concern to the vasorelaxant effect of scopoletin.
Kwon, Do Hoon,Kim, Sulhee,Jung, Yang Ouk,Roh, Kyung-Hye,Kim, Leehyeon,Kim, Byeong-Won,Hong, Seung Beom,Lee, In Young,Song, Ju Han,Lee, Woo Cheol,Choi, Eui-Ju,Hwang, Kwang Yeon,Song, Hyun Kyu Informa UK (TaylorFrancis) 2017 AUTOPHAGY Vol.13 No.1
<P>Hosts utilize macroautophagy/autophagy to clear invading bacteria; however, bacteria have also developed a specific mechanism to survive by manipulating the host cell autophagy mechanism. One pathogen, Legionella pneumophila, can hinder host cell autophagy by using the specific effector protein RavZ that cleaves phosphatidylethanolamine-conjugated LC3 on the phagophore membrane. However, the detailed molecular mechanisms associated with the function of RavZ have hitherto remained unclear. Here, we report on the biochemical characteristics of the RavZ-LC3 interaction, the solution structure of the 1:2 complex between RavZ and LC3, and crystal structures of RavZ showing different conformations of the active site loop without LC3. Based on our biochemical, structural, and cell-based analyses of RavZ and LC3, both distant flexible N- and C-terminal regions containing LC3-interacting region (LIR) motifs are important for substrate recognition. These results suggest a novel mechanism of RavZ action on the phagophore membrane and lay the groundwork for understanding how bacterial pathogens can survive autophagy.</P>
Current Controller Design of a Grid Connected Inverter Using LCL Filter
Kwon-Sik Park,Byuong-Jun Seo,Kwang-Rae Jo,Jin-Yong Heo,Haksoo Kim,Eui-Cheol Nho 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This Paper proposes a current controller design method of grid connected inverter using an LCL filter without damping method. In case of a grid side current control, it is not necessary for the system to use the damping method if the ratio of the LCL filter resonant frequency to a system sampling frequency is larger than 1/6. However, if the grid impedance is changed, it is not sure whether the system is in the stable region or not. If an LPF (Low Pass Filter) is used in the feedback path of the system, the stable region of the inverter system can be expanded. This paper proposes a new current controller using the LPF in the feedback path. The proposed controller uses the HC (Harmonic Compensator) in order to improve the grid current quality. The validity of the proposed method is verified through simulation.
Kim, Eui Joo,Kwon, Kwang An,Lee, Young Eun,Kim, Ju Hyun,Kim, Se-Hee,Kim, Jung Ho The Korean Society of Ginseng 2018 Journal of Ginseng Research Vol.42 No.3
Background: The incidence of colorectal cancer (CRC) is increasing, with metastasis of newly diagnosed CRC reported in a large proportion of patients. However, the effect of Korean Red Ginseng extracts (KRGE) on epithelial to mesenchymal transition (EMT) in CRC is unknown. Therefore, we examined the mechanisms by which KRGE regulates EMT of CRC in hypoxic conditions. Methods: Human CRC cell lines HT29 and HCT116 were incubated under hypoxic (1% oxygen) and normoxic (21% oxygen) conditions. Western blot analysis and real-time PCR were used to evaluate the expression of EMT markers in the presence of KRGE. Furthermore, we performed scratched wound healing, transwell migration, and invasion assays to monitor whether KRGE affects migratory and invasive abilities of CRC cells under hypoxic conditions. Results: KRGE-treated HT29 and HCT116 cells displayed attenuated vascular endothelial growth factor (VEGF) mRNA levels and hypoxia-inducible $factor-1{\alpha}$ ($HIF-1{\alpha}$) protein expression under hypoxic conditions. KRGE repressed Snail, Slug, and Twist mRNA expression and integrin ${\alpha}V{\beta}6$ protein levels. Furthermore, hypoxia-repressed E-cadherin was restored in KRGE-treated cells; KRGE blocked the invasion and migration of colon cancer cells by repressing $NF-{\kappa}B$ and ERK1/2 pathways in hypoxia. Conclusions: KRGE inhibits hypoxia-induced EMT by repressing $NF-{\kappa}B$ and ERK1/2 pathways in colon cancer cells.
Hwang Eui-Chang,Kim Dong Kyue,Moon Kwang-Seok,Kwon Ki-Ryong Korea Multimedia Society 2005 멀티미디어학회논문지 Vol.8 No.6
This paper is proposed a watermarking technique for copyright protection of multimedia contents. We proposed adaptive watermark detection algorithm using stochastic perceptual model and statistical decision method in DMWT(discrete multi wavelet transform) domain. The stochastic perceptual model calculates NVF(noise visibility function) based on statistical characteristic in the DMWT. Watermark detection algorithm used the likelihood ratio depend on Bayes' decision theory by reliable detection measure and Neyman-Pearson criterion. To reduce visual artifact of image, in this paper, adaptively decide the embedding number of watermark based on DMWT, and then the watermark embedding strength differently at edge and texture region and flat region embedded when watermark embedding minimize distortion of image. In experiment results, the proposed statistical decision method based on multiwavelet domain could decide watermark detection.