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렙틴 수용체가 형질 도입된 신경세포에서 ER Stress로 유도된 렙틴저항성에 대한 일산화탄소의 억제작용
김성주,김택상,류현열,정헌택 고신대학교 의과대학 2010 고신대학교 의과대학 학술지 Vol.25 No.1
연구 배경 및 목적: 렙틴이 음식의 섭취 양과 체중의 증가를 억제하는 중요한 호르몬 역할을 한다는 사실은 잘 알려졌다. 또한 렙틴에 대한 저항성이 비만의 중요한 원인이라는 연구가 많이 보고되고 있다. 그러나 렙틴 저항성에 대한 구체적인 기전은 아직 밝혀져 있지 않았다. 최근 endoplasmic reticulum (ER) 스트레스에 의한 unfolded protein response (UPR) 가 렙틴에 대한 저항성을 유발한 다는 보고가 있었다. 연구 대상 및 방법: 일산화탄소(carbon monoxide, CO)는 heme oxygenase (HO)-1이 헴(heme)을 산화적 분해로 만들어내는 무색, 무미, 무취의 기체로 항산화, 항염증, 항세포분열 및 항세포고사 작용을 나타내며 조직의 손상에 대한 세포보호작용을 한다. 최근 CO는 ER stress sensor 중의 하나인 protein kinase R-like endoplasmic reticulum kinase (PERK) 를 선택적으로 활성화 시키며 인산화된 PERK 는 HO-1의 전사조절인자인 Nrf2를 인산화로 활성화시켜 결국 HO-1의 유전자 발현을 촉진함이 보고 되였다. 또한 CO로 유도된 PERK의 활성화는 eukaryotic translation initiation factor (eIF) 2a를 인산화로 활성화 시키고 인산화된 eIF2a는 전사인자인 activating transcription factor (ATF)-4의 발현을 유도하지만 CO는 ER stress의 다른 두 개 sensors인 inositol requiring enzyme (IRE) 1a와 하위신호전단물질인 X-box binding protein (xbp)-1이나 ATF6의 활성화에는 영향을 미치지 아니한다. 그러나 ER stress 유발인자들인 thasigargin (TG), tunicamycin (TM), homocysteine 등으로 Xbp-1이나 ATF6가 활성화되는 것을 억제한다. 연구 결과: 본 연구에서는 ER stress 에 의해 활성화되는 UPR에 의해 유발되는 렙틴 저항성이 CO에 의하여 차단될 것이라는 가정을 세우고 다음과 같은 실험결과를 얻었다. TG나 TM에 의해 유도된 ER stress반응 즉 UPR은 렙틴의 신호전달로 야기되는 phospho-signal transducer and activation of transcription (STAT) 3로 인산화되는것을 억제시켰다. 그러나 ER stress를 유도시킬 시 CO를 CO releasing molecule (CORM)으로 처리하였을 때 UPR에 의한 렙틴의 신호전달로 말미암는 STAT3 인산화의 차단이 CO의 양과 노출 시간에 비례하여 제거 되었다. 결론: 이러한 실험결과는 CO에 의한 PERK 인산화는 ER stress 유도체에 의한 IRE1a의 하위 신호전달물질인 Xbp-1 이나 ATF6의 활성화를 억제하여 ER stress 반응인 UPR에 의한 렙틴 저항성을 차단함을 시사한다. 결론적으로 이러한 실험결과는 CO유도체를 이용하여 병인적인 렙틴 저항에 의한 여러 질병을 치료할 수 있음을 시사한다. Background: It is well known that leptin is an important circulating signal for the inhibition of food intake and the gain of body weight. Accumulating data suggest that leptin resistance has been considered to be one of the main causes of obesity. However, the detailed mechanism of leptin resistance is not known yet. Recently, endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) is reported to be responsible for the leptin resistance. Materials & methods: Carbon monoxide (CO), a reaction product of the cytoprotective heme oxygenase (HO)-1, is anti-apoptotic in a variety of models of cellular injury. Exogenous CO activated Nrf2 through the phosphorylation of protein kinase R-like endoplasmic reticulum kinase (PERK), resulting in HO-1 expression. CO-induced activation of PERK was followed by the phosphorylation of eukaryotic translation initiation factor 2a and the expression of activating transcription factor 4. However, CO fails to induce X-box binding protein-1 expression and activating transcription factor 6 cleavage. CO prevented X-box binding protein-1 expression and activating transcription factor 6 cleavage induced by ER-stress inducer such as thasigargin (TG), tunicamycin (TM) and homocysteine. Results: In the present study, we hypothesized that exogenous CO might block the leptin resistance which is induced by UPR during ER stress. Thasigargin or tunicamycin was used to induce ER stress. The activation status of leptin signals were measured by western blotting analysis using a phospho-signal transducer and activation of transcription3 (STAT3) antibody. In this study, ER stress markedly inhibited leptin-induced STAT3 phosphorylation. Conculusion: These results suggest that ER stress induces leptin resistance and exogenous CO-induced phosphorylation of PERK branch reversed ER stress-induced leptin resistance. Moreover, CO releasing molecule (CORM) blocks the inhibition of leptin-induced STAT3 phosphorylation. Together, the pathological mechanism of leptin resistance could be ameliorated by the use of exogenous CO..
라유찬,오승철,오성택 남서울대학교 공학연구센터 2001 공학연구 Vol.2 No.-
The Wireless LAN and Bluetooth use the same frequency Bandwidth 2.4GHz and it leads to cause interference between the systems and, on the basis of IEEE 802.11, we made a test and analysis on the influence derived there from. We got the test result by setting the test condition of 30mW for the wireless LAN Tx power and 100mW for Bluetooth Tx power. When there is no wireless LAN, regardless of distance between Master and Slave, Throughput was stable enough with 0.57Mbps, and when Bluetooth Slave approached to the Wireless LAN, before 25 feet, Throughput was sharply decreased from 0.3Mbps and, after 25 feet, it was so seriously influenced that it cannot be used again. And, when it is located far from of 30 feet, regardless of distance, Throughput was around 0.5Mbps and was slightly influenced compared with when there is no Wireless LAN, but is wasn't serious.
나유찬,오승철,오성택 남서울대학교 공학연구센터 1999 공학연구 Vol.1 No.-
It is possible to transmit a large amount of sound, video, and data over wired networks based upon the growing Information Superhighway. However, the existing available access networks are composed of much lower speed two-pair networks that can not handle multimedia information. To solve this problem, wireless access techniques yielding mobility and portability must be more efficient than increasing the capacity of wired networks. Also the WLL system is emerging as a highly attractive solution for the local loop network in many countries. It is one of the important means of providing telephone services more cheaply and quickly than through a wireline. Therefore in this paper, we introduce WLL. and the LMCS technology, (and service trends recently new local loop technique) which are now spotlighted in wireless access technology fields.
A Watermarking Scheme for Mobile 3D Game Contents Based on Buyer-Seller Watermarking Protocol
Seong-Geun Kwon,Suk-Hwan Lee,Eung-Ju Lee,Ki-Ryong Kwon,Teak-Young Seong,Sung-Ho Bae 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
This paper presents a watermarking method for copyright protection and illegal copy prevention of mobile 3D contents. The proposed method embeds copyright information and user's phone number into spatial domain and encryption domain of mobile animation data based on Buyer-Seller watermarking protocol. Furthermore, we insert user's operation key so that only authorized user can play 3D animation game in mobile device.
DCT and Homomorphic Encryption based Watermarking Scheme in Buyer-seller Watermarking Protocol
Seong, Teak-Young,Kwon, Ki-Chang,Lee, Suk-Hwan,Moon, Kwang-Seok,Kwon, Ki-Ryong Korea Multimedia Society 2014 멀티미디어학회논문지 Vol.17 No.12
Buyer-seller watermarking protocol is defined as the practice of imperceptible altering a digital content to embed a message using watermarking in the encryption domain. This protocol is acknowledged as one kind of copyright protection techniques in electronic commerce. Buyer-seller watermarking protocol is fundamentally based on public-key cryptosystem that is operating using the algebraic property of an integer. However, in general usage, digital contents which are handled in watermarking scheme mostly exist as real numbers in frequency domain through DCT, DFT, DWT, etc. Therefore, in order to use the watermarking scheme in a cryptographic protocol, digital contents that exist as real number must be transformed into integer type through preprocessing beforehand. In this paper, we presented a new watermarking scheme in an encrypted domain in an image that is based on the block-DCT framework and homomorphic encryption method for buyer-seller watermarking protocol. We applied integral-processing in order to modify the decimal layer. And we designed a direction-adaptive watermarking scheme by analyzing distribution property of the frequency coefficients in a block using JND threshold. From the experimental results, the proposed scheme was confirmed to have a good robustness and invisibility.
A ROBUST VIDEO WATERMARKING BASED ON DWT FRAMEWORK AGAINST TRANSCODING
Teak-Young Seong,Seon-Ja Lim,Chong-Ho Woo,Jong-Keuk Lee,Suk-Hwan Lee,Ki-Ryong Kwon 한국멀티미디어학회 2007 한국멀티미디어학회 국제학술대회 Vol.2007 No.-
Recently, transcoding of the video contents in the environments of heterogeneous multimedia services-wired/wireless Internet and mobile networks using cellular phones, DMB(Digital Multimedia Broadcasting), IPTV(Internet Protocol Television) etc. - is raised up as a new issue. Therefore, video watermarking techniques are confronted with difficulty about not only existing video compression but also a modification considering time and spatial resolution under transmission bandwidth. In this paper, for the transcoding, we proposed a new video watermarking scheme based on DWT framework using multiresolution property of DWT and binary image watermark playing a role of synchronization pattern. In the experimental results, we confirmed robustness and invisibility of the proposed scheme about transcoding.