백서 복직근 피판의 허혈-재관류 손상에 대한 고압 산소 치료의 효과.

Dept. of Medicine/박사[한글]허혈-재관류 손상을 입은 조직에 대한 고압산소는 조직의 생존율을 높이는 것으로 알려져 있다. 하지만 그 원리는 정확히 밝혀 지지 않은 채 아직 연구 단계에 머물러 있다. 본 논문은 백서 복직근피판에 있어 허혈-재관류 손상에 미치는 고압산소의 치료 효과를 접착 분자 (adhesion molecule)인 내피 세포의 intercellular adhesion molecule-1(ICAM-1) 과 중성구의 CD18을 중점적으로 분석하였다. 백서 복직근피판은 5 x 6 cm. 의 크기로 하나의 혈관경을 중심으로 거상 되었다. 70마리의 백서를 4개의 군으로 다음과 같이 분류하였다; 제 0 군: sham (n=10), 제 I 군: 4 시간의 허혈 손상 후 재관류 시행 (n=20), 제 II 군: 4 시간의 허헐손상중 후반 90분의 고압산소 치료 후 재관류 시행 (100% 산소, 2.5 절대기압) (n=20), 제 III 군: 4 시간의 허혈 손상 후 재관류 시행 즉시 90분 간의 고압산소 치료 (100% 산소, 2.5 절대기압) (n=20). 실험 분석은 피판의 생존율, 조직학적 관찰, myeloperoxidase (MPO) 정량, CD18의 유동세포계산 (flow cytometry), 및 ICAM-1 mRNA에 대한 Northern analysis로 이루어 졌다. 피판의 생존율은 제 II 와 III 군이 I 군 보다 높은 결과를 보였다 (p< 0.05). 백혈구의 내피에 대한 접착성을 실험 후 24시간과 5일째 분석한 결과, 제 I 군이 제 II 와 III 군 보다 높은 접착율을 보였다 (p < 0.05). MPO 정량은 24시간에 분석한 결과 제 I 군이 제 II 와 III 군 보다 높은 수치를 나타냈다 (p < 0.05). ICAM-1 에 대한 면역조직화학 염색과 ICAM-1 mRNA 분석은 제 II 와 III 군이 제 I 군에 비해 약한 발현 현상을 보였다. CD18은 모든 군에서 유사한 정도의 발현을 보였다. 분석 중 제 II 와 III 군은 별 차이가 없었다.위의 분석을 토대로 다음과 같은 결론을 유추하였다: 1) 고압 산소는 백서복직근 피판에 백혈구의 유입 되는 양을 줄인다. 2) 허혈-재관류 손상후 CD18 과 ICAM-1 의 발현은 증가시켜 백혈구가 내피에 접착 하는 것을 촉진 시킨다. 3) 고압산소는 CD18에 미치는 효과는 미미하지만 ICAM-1 의 발현을 줄인다. 4) 재관류 전 또는 후에 시행하는 고압 산소의 치료는 별 차이가 없다. 본 연구는 고압산소가 허혈-재관류 손상을 입은 피판에 대해 생존율을 증가 시키며 내피 ICAM-1의 발현 억제 현상 (down-regulation) 을 그 기전으로 볼 수 있었다. [영문] The effect of hyperbaric oxygen is known to increase survival of ischemic tissue after reperfusion but its mechanism is not fully understood. The purpose of this study was to evaluate the effect of hyperbaric oxygen on musculocutaneous flap of rat against ischemia-reperfusion injury, focusing on the mechanism involving the expression of adhesion molecules such as intercellular adhesion molecule 1 (ICAM-1) of endothelial cells and CD18 of neutrophils. A transverse rectus abdominis musculocutanous (TRAM) flap (6 x 5 cm.) supplied by a single pedicle, superior epigastric artery and vein, was elevated in 70 Sprauge-Dawley rats. The rats were divided into 4 groups; Group 0: sham (n = 10), Group I: 4 hour ischemia followed by reperfusion (n=20), Group II: 4 hour ischemia and hyperbaric oxygen (100% oxygen, 2.5 atmosphere absolute, during the last 90 minutes of ischemia before reperfusion) followed by reperfusion (n = 20), and Group III: 4 hour ischemia followed by reperfusion and hyperbaric oxygen (100% oxygen, 2.5 atmosphere absolute, after reperfusion for 90 minutes) (n = 20). The study consisted of gross examination for flap survival, histology, myeloperoxidase (MPO) assay, flow cytometric study of CD18, and Northern analysis on ICAM-1 mRNA expression. The gross measurement of the flap showed increased survival in group II and III compared to group I (p < 0.05). The leukocytes adherent to the endothelium was counted at 24 hours and on the 5th day: Group I was significantly increased compared to group II and III (p < 0.05). The myeloperoxidase (MPO) assay of TRAM flap at 24 hours revealed significant increase of group I compared to group II and III (p < 0.05). The expression of CD18 was similar between group I, II, and III. The immunohistochemical staining for ICAM-1 and Northern analysis on ICAM-1 mRNA showed decreased expression in group II and III compared to group I. Through out the analysis, group II and III did not show any significant differences. These results suggests; 1) Hyperbaric oxygen reduces the introduction of leukocytes in the TRAM flap but not enough to prevent adhesion of neutrophils on endothelial cells. 2) Ischemia-reperfusion injury increases the expression of CD18 and ICAM-1 and causes increased adhesion of leukocytes on endothelium. 3) The hyperbaric oxygen does not alter the expression of CD18 but decreases the expression of ICAM-1. 4) The point of application for hyperbaric oxygen, whether applied before or after reperfusion, did not show any differences in outcome. In conclusion, the application of hyperbaric oxygen against ischemia-reperfusion injury increases the flap survival and the beneficial effect may be explained by a protective mechanism involving down-regulation of ICAM-1 on endothelial cells.ope

Preparation of 99mTc-HYNIC-PEG-liposomes for imaging focal sites of infection

임상병리학과/석사[영문] [한글] 염증부위를 국소화 진단할 수 있는 ^(99m)Tc-HYNIC-PEG-liposome을 합성하고 이를 이용 하여 농양 형성 동물모델에서의 생체분포와 생체영상을 분석함으로써 염증진단 시약으로 서의 가능성 여부를 확인하고자 하였다. 6-Chloronicotinic acid를 출발물질로 하여 6-hy drazinopyridine-3-carboxylic acid, 6-BOC-hydrazino pyridine-3-carboxylic acid, succ inimidyl 6-BOC-hydrazinopyridine-3-carboxylic acid를 순차적으로 합성하였고, 합성수 율은 각각 88.5%, 93.7%, 93.2%였다. Succinimidyl 6-BOC-hydrazinopyridine-3-carboxyli c acid의 최종합성수율은 77.3%였다. Triethylamine을 이용해 합성된 succinimidyl 6-BOC -hydrazino pyridine-3-carboxylic acid와 DSPE(distearoyl phosphatidylethanolamine)를 접합하였다. HYNIC-DSPE를 제조한 후에 EPC:PEG-DSPE:HYNIC-DSPE:cholesterol을 1.85:0. 15:0.07:1의 몰 비로 혼합하여 HYNIC-PEG-liposome을 제조하였다. 제조된 HYNIC-PEG-lipo some의 직경은 106 nm였고, PEG-liposome에 접합된 HYNIC의 농도는 1.08 mM이었다. HYNIC -PEG-liposome의 개수는 1 ㎖에 5.2×10^(14)개가 존재하였고, PEG-liposome 한 개당 HYN IC은 약 1250개가 접합되었다. 제조된 HYNIC-PEG-liposome에 SnCl₂·2H₂O와 tricine을 이용하여 ^(99m)Tc를 표지하였다. ^(99m)Tc-HYNIC-PEG-liposome과 혈청을 섞어서 실온과 37℃에서 24시간까지 안정성을 확인하였다. ^(99m)Tc-HYNIC-PEG-liposome에 DTPA, cystei ne, glutathione을 각각 과량의 몰 비로 섞고 37℃에서 1시간 반응 후에 transchelation 을 통해 안정성을 확인하였다. 살아있는 S. aureus 1×10^(10) (CFU, colony forming uni ts)를 Sprague Dawley 백서 좌측 대퇴부에 근육 내 주사하고, 대조군으로 죽은 S. aureus 를 동량 우측 대퇴부에 접종하여 농양이식백서를 제조하고, 이를 이용하여 ^(99m)Tc-HYNI C-PEG-liposome의 생체분포와 생체영상을 얻었다. ^(99m)Tc의 표지 수율은 99%이상이었으 며, 혈청 내에서 24시간까지 93.5%이상의 안정성을 나타내었다. DTPA, cysteine, glutath ione을 각각 1000배의 몰 비를 첨가한 경우 ^(99m)Tc-HYNIC-PEG-liposome의 방사화학적순 도가 각각 98%, 96%, 99%으로서 안정하였다. 농양대 혈액비, 농양대 근육비, 농양대 대조 군의 비는 각각 2시간 후에 0.53, 2.84, 1.23이었고, 6시간 후에 0.82, 3.79, 1.47이었고 , 24시간 후에서는 1.33, 5.57, 1.03이었다. ^(99m)Tc-HYNIC-PEG-liposome의 농양이식백 서에서 생체분포는 비장과 간에서 %ID/g이 6시간에서 가장 높았으며 24시간에서는 감소하 였다. 혈중 %ID/g은 2시간, 6시간, 24시간 후에 각각 0.124, 0.071, 0.041로 나타나 혈중 제거율이 빠름을 알 수 있었다. 영상실험에서는 6시간에서 S. aureus에 의한 농양부위에 ^(99m)Tc-HYNIC-PEG-liposome의 집적이 가장 높은 것을 확인하였으며, 대조부위에서는 집 적량이 작았다. 따라서 ^(99m)Tc-HYNIC-PEG-liposome을 손쉽게 제조할 수 있었으며 세균 에 의한 염증부위에 ^(99m)Tc-HYNIC-PEG-liposome이 특이적으로 국소화되는 것을 관찰함 으로써 임상에서 염증진단시약으로서 이용가능성을 확인하였다. -------------------- 핵심되는 말 : ^(99m)Tc, HYNIC, liposome, 생체분포, 생체영상 Preparation of 99mTc-HYNIC-PEG-liposomes for imaging focal sites of infection To evaluating the effectiveness of ^(99m)Tc labeled-liposomes as an agent to diagnose abscess, ^(99m)Tc-HYNIC(hydrazino nicotinamide)-PEG(polyethylene glycol)-liposomes were prepared and the biodistribution of the liposomes was investigated in a rat model bearing abscess. In order to synthesize HYNIC- DSPE (distearoyl phosphatidyl ethanolamine) which is a crucial component for ^(99m)Tc chelation, first of all succinimidyl 6-BOC-hydrazinopyridine-3-carboxylic acid was synthesized from 6-chloronicotinic acid by three sequential reactions with 77.3% overall yield. The chemical structure of succinimidyl 6-BOC- hydrazinopyridine-3-carboxylic acid was determined by 1H-NMR analysis. A DSPE derivative of succinimidyl 6-BOC-hydrazinopyridine-3-carboxylic acid was transformed into HYNIC-DSPE by HCl/dioxane. HYNIC-PEG-liposomes were prepared by hydration of the dried lipid mixture of egg phosphatidyl choline EPC:PEG-DSPE:HYNIC-DSPE:cholesterol (1.85:0.15:0.07:1, molar ratio). The HYNIC concentration in the PEG-coated liposome dispersion was 1.08 mM. In condition of considering the measured liposomal size of 106 nm, the phospholipid concentration of 77.5 μ㏖/㎖ and the liposomal particle number of 5.2×10^(14) liposomes/ml, it is corresponded to approximate 1,250 nicotinyl hydrazine group per liposome in HYNIC-PEG-liposome. The HYNIC-PEG- liposomes were labeled with ^(99m)Tc in the presence of SnCl₂·2H₂O (a reducing agent) and tricine (a coligand). The removal of free ^(99m)Tc was not necessary because the labeling efficiency were over 99%. To investigate the level of in vivo transchelation of ^(99m)Tc in the liposomes, the ^(99m)Tc-HYNIC-PEG-liposomes were incubated with a molar excess of DTPA, cysteine or glutathione solutions at 37℃ for 1 hour. The radiolabeled liposomes maintained 98%, 96% and 99% of radioactivity after incubation with respective compounds. The radiolabeled liposomes were also incubated in the presence of human serum at 37℃ for 24 hours. The radiolabeled liposomes still possessed over 90% of the radioactivity after incubation with serum. An abscess model was prepared in the left calf muscle of rats by subcutaneous administration of 1×10^(10) colony forming units of live S. aureus. The same dose of heat-killed S. aureus was administered to right calf muscle for a control model. The ^(99m)Tc-HYNIC-PEG-liposomes were highly localized in the spleen and liver. Two, six, and twenty four hours post injection, the abscess/blood ratios were 0.53, 0.82 and 1.33, and the abscess /muscle ratios were 2.84, 3.79, and 5.57, and the abscess/control ratios were 1.23, 1.47, and 1.03, respectively. The uptake of ^(99m)Tc-HYNIC-PEG-liposomes by the abscess tissue was greater than the uptake by the control tissue, according to analysis of images taken by a gamma camera after 6 hour post injection. This procedure of ^(99m)Tc-labeling to HYNIC-liposomes is rapid, efficient and easy to perform. The ^(99m)Tc-HYNIC-PEG-liposomes exhibited the enhanced stability in vitro, as well as in vivo. These results suggest that the ^(99m)Tc-HYNIC-PEG-liposomes can be applied in diagnosis of abscess as an imaging agent.ope

The Superficial Circumflex Iliac Artery Perforator Flap in Lower Extremity Reconstruction

The Superficial Circumflex Iliac Artery Perforator Flap in Lower Extremity Reconstructio

한국 농업 R&D 투자 효과 분석

학위논문(석사)--서울대학교 대학원 :농경제사회학부,2002.Maste

COMMUNICATION APPARATUS AND MULTIPLE ACCESS APPARATUS FOR TRANSCEIVING DATA, AND METHOD THEREOF

다중 접속 장치와 접속한 통신 장치는 상기 통신 장치와 상기 다중 접속 장치간 채널 상태에 기초하여 상기 통신 장치의 채널 이득값을 연산하는 연산부, 상기 연산된 채널 이득값에 기초하여 데이터의 전송 여부를 결정하는 제어부 및 상기 결정에 기초하여 상기 다중 접속 장치에게 데이터를 전송하는 데이터 전송부를 포함하고, 상기 다중 접속 장치는 상기 다중 접속 장치에게 전송되는 복수의 데이터간 물리적 간섭에 기초하여 상기 데이터를 복원한다

The emergence of virtual education during the COVID-19 pandemic: The past, present, and future of the plastic surgery education

Background: Since the global outbreak of coronavirus disease-2019 (COVID-19), plastic surgeons were forced to transition from traditional didactics to virtual lectures to practice "social distancing." As this method of education continues to be widely used, understanding the current trend of its usage is critical. In this study, we performed a survey study of virtual lecture attendees and presenters to determine current usage and general consensus on virtual lectures in plastic surgery education. Methods: An electronic survey was sent to attendees and presenters of virtual lectures using Google Forms. Demographic data, webinar usage patterns, and views on virtual lectures were collected. Results: A total of 417 surveys were received. Prior to the COVID-19 era, 39.1percent of attendees did not use virtual lectures and 45.6percent of presenters did not give webinars at all. Both groups reported that the lack of opportunities and need were the most common cause of no use of lectures or webinars. After the outbreak, 35.4percent of attendees now use virtual lectures daily and 51.4percent of presenters give lectures weekly. Over 90percent of the study population reported a positive experience with the virtual lectures due to increased interaction, convenience, outreach, and usability. Finally, over 75percent stated that virtual lectures might replace classroom lectures in the future. Conclusion: Our study shows that a majority of plastic surgeons have begun to use and give virtual lectures daily after the COVID-19 outbreak. Virtual education is a powerful and versatile tool that has great potentials, and it may continue to serve as a part of surgical training in the future. (C) 2021 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by El-sevier Ltd. All rights reserved

A study on loss-tolerant PAM-4 receiver with 1-tap FFE

Master본 논문에서는 외부에서 캐패시터 값만을 조절하여 다양한 데이터 속도에 따라 손실된 신호를 복원해 내는 PAM-4 수신기를 어떻게 구현하였는지를 설명한다. 이 수신기는 수신된 신호의 crossing point를 1개로 줄여서 eye의 너비를 넓히는 것을 하나의 목표로 한다. 그 목표를 이루기 위하여 기본적으로는 전류를 적분하는 기술을 활용하였다. 그리고 2nd tap에서의 전류의 모양을 수학적 유도로 구해낸 모양과 일치시키는 과정을 설명하였다. 그 결과, crossing point를 줄이고 eye의 너비를 넓힐 수 있었다. 이 회로는 Half-rate clock을 활용하기 때문에 두 개의 블락이 있다. 각 블락은 전체 clock 주기의 절반은 적분하는 노드를 pre-charge 하는 데에 사용하고, 나머지 절반의 주기에는 신호를 복원해낸다.Whereas NRZ signal has one crossing point, PAM-4 signal has theoretically 27 crossing points. The points bring reduction of eye-width and it causes weakness on clock jitter. This thesis presents a PAM-4 receiver which recovers distorted PAM-4 signal with only one crossing point in diverse insertion loss (IL) environment. Implemented in 28-nm CMOS LP technology, the receiver operates from 20Gb/s with 15.5-dB loss to 40Gb/s with 13.3-dB loss. Recovered signals are measured in simulation

인지 라디오 시스템에서 다이버시티 이득에 관한 연구

학위논문(박사) - 한국과학기술원 : 전기및전자공학과, 2014.2, [ viii, 98 p. ]Cognitive radio (CR) is considered as one of promising methods to alleviate the spectrum scarcity caused by the increasing demand for wireless services and the existing exclusive spectrum allocation policy. The CR enables unlicensed users (secondary users) to access the under-utilized spectrum which is assigned to licensed users (primary users) while guaranteeing quality-of-service (QoS) requirements of primary users. However, it is hard for the secondary user to get a certain level of performance because the performance of secondary users’ communications are severely degraded by the QoS constraints imposed on the secondary users. Recently, diversity techniques in CR systems have been actively investigated that compensate the performance degradations of the secondary network by mitigating or exploiting the fluctuation of fading channels. This dissertation presents three different forms of diversity gain in cognitive radio systems: the diversity gain originated from relay, multiuser, and access mode switching.First, we consider the cooperative diversity gain in underlay CR systems where secondary users access the spectrum licensed to primary users under interference power constraint at primary receivers. Our analysis shows that the cooperative diversity gain has different characteristics from that in non-CR systems since the transmit power of a secondary transmitter is limited by the interference power constraint. If a fixed interference power constraint is imposed, the cooperative diversity gain is lost regardless of the number of relays even if peak transmit power grows to infinity. We analyze the critical value of peak transmit power beyond which increasing peak transmit power does not help in improving the outage probability. However, if a proportional interference power constraint is imposed, a full diversity gain is shown to be attained even without instantaneous interference channel information at the secondary transmitters.Second, we discuss the multius...한국과학기술원 : 전기및전자공학과