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( Dong Wook Han ),( Jung Yoon Bae ),( Suong Hyu Hyon ) 한국조직공학·재생의학회 2009 조직공학과 재생의학 Vol.6 No.1
Although epigallocatechin-3-O-gallate(EGCG), a major poly phenolic constituent of green tea, has various pharmacological and biological activities including anti-carcinogenic, anti-thrombotic and anti-inflammatory effects, relatively a little is known about its beneficial effects on the non-frozen preservation of mammalian cells and tissues. In this study, articular cartilages from human knee joint were pretreated with 1 mM EGCG for 1 d and then preserved in serum-free RPMI 1640 media with 1% antibiotic-antimycotic solution at 4℃ for 1, 2 and 4 wk. After cold preservation, chondrocyte viability(CCK-8 assay), biochemical and immunohistochemical composition[glycosaminoglycans and(type II)collagen], and biomechanical property(compressive elastic modulus) were assessed, respectively. Chondrocyte viability of cartilages pretreated with EGCG was significantly well-maintained for at least 2 wk with high contents of glycosaminoglycan and total collagen. These beneficial effects of EGCG pretreatment were more confirmed by histological and immunohistochemical observations showing well-preserved cartilaginous structures and delayed denaturation of the extracellular matrices in preserved specimens. The compressive elastic modulus(MPa) of cartilages pretreated with EGCG was well-maintained as much as that of fresh specimens without any increase as the progress in the preservation period. Here were also found that fluorescein isothiocyanate-conjugated EGCG were widely distributed through the matrix and clearly observed at the chondrocytes in the lacunas. Taking these results into consideration, it is suggested that EGCG may play an effective role in preserving articular cartilages, which be exploited to craft strategies for the long-term preservation of osteochondral allografts under cold storage conditions.
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Direct generation of neurons, neural stem cells, and brains
Dong Wook Han 한국수정란이식학회 2016 한국수정란이식학회 학술대회 Vol.2016 No.10
Introducing lineage-specific transcription factors (TFs) into somatic cells enables the induction of distinct cellular identities without the need to first pass through a pluripotent stem cell (PSC) state. We and others have demonstrated the direct conversion of somatic cells into adult stem cells or progenitor cells, such as angioblast-like progenitor cells, hematopoietic stem cells, and neural stem cells. The process underlying direct conversion is known to be relatively simpler and faster than that of induced pluripotent stem cell (iPSC) generation. Furthermore, directly converted cells have been shown to exhibit therapeutic potential following transplantation into respective disease models without obvious evidence for tumor formation. Thus, TF-mediated direct conversion technology has been considered as an alternative to iPSC technology for patient-specific cell- and tissue-replacement therapies. Here we show our recent findings describing the robust direct conversion of differentiated somatic cells into distinct cellular identities. Furthermore, we also show the recent 3D organoid technology for generating brain tissues from human pluripotent stem cells.
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자기통제 결과지식을 통한 시간타이밍 학습의 효과적인 연습구조 모색
한동욱(DongWookHan) 한국체육학회 2010 한국체육학회지 Vol.49 No.6
본 연구는 운동학습 단계에 따라 자기통제 결과지식(KR)을 언제 제공하는 것이 시간타이밍 학습에 효과적인지를 규명하는 데 목적이 있다. 이를 위해 학습단계를 전반부와 후반부로 구분하여 자기통제 KR-자기통제 KR, 자기통제 KR-KR, KR-자기통제 KR, KR-KR 집단에 연구대상자(n=40)를 무선 할당하였다. 모든 연구대상자는 사전검사, 습득단계, 파지 및 전이검사에 참여하였으며 상대적 타이밍 오차와 절대적 타이밍 오차를 통하여 네 개의 집단에 따른 시간타이밍의 학습 차이를 살펴보았는데, 연구결과는 다음과 같다. 사전검사에서는 네 집단이 유사한 시간타이밍 능력을 나타냈고, 습득단계에서는 연습이 진행됨에 따라 모든 집단의 시간타이밍 오차가 전반적으로 감소하였다. 그리고 파지검사에서 두 개의 타이밍 변인에 대하여 집단간 유의미한 차이가 나타나지 않았지만 전이검사에서는 전반부에 모든 수행에 대해 KR을 제시받고 후반부에 자기통제 KR을 받는 연습방법(KR-자기통제 KR)이 상대적 타이밍과 절대적 타이밍을 동시에 학습시키는데 가장 유용한 전략이었다. 따라서 본 연구결과는 학습단계에 따른 자기통제 KR의 조절전략을 통해 전이과제와 같은 새로운 과제의 시간타이밍 학습 효과를 높일 수 있다는 것을 제시해 주었다. The aim of this study was to search for an optimal practice schedule considering the self-controlled KR on the stages of practice. Participants (n=40) were randomly assigned to one of four acquisition groups defined by the practice schedules (self -controlled KR - self-controlled KR, self-controlled - KR, all feedback - self-controlled KR, and KR - KR). The first part of the group name (e.g., self-controlled KR - KR) indicates the practice schedule used in Blocks 1-6 (e.g., self- controlled KR) and the second part (e.g., KR) indicates the practice schedule used in Blocks 7-12. The experiment consisted of a pretest session, two acquisition sessions, a retention session, and a transfer session. The dependent variables of interest were relative timing error and absolute timing error. The results represented that participants had similar temporal-timing skills in the pretest. In the two acquisition sessions, three temporal timing errors were smaller as participants practised. Most importantly, when considering relative and absolute timing the KR - self controlled KR schedule resulted in performance superior to that of all other groups in the transfer session though two temporal timing variables did not differ from each other in the retention session. We conclude that we might product the effects of the temporal timing learning on a new task like a transfer task through controllable strategies of the self-controlled KR on the stage of practice.
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인문,사회과학편 : 자세조건에 따른 압력중심의 복잡성 연구
고지현(JiHyunKo),한동욱(DongWookHan) 한국체육학회 2014 한국체육학회지 Vol.53 No.5
이 연구는 두 개의 지면반력기를 사용하여 서로 다른 자세조건에 따른 왼발, 오른발, 전체 압력중심의 복잡성의 변화를 분석하는 데 목적이 있다. 또한 압력중심의 가변성과의 비교를 통해 상호 간의 관계를 규명하였다. 12명의 건강한 성인들로 구성된 피험자 집단은 무선할당 된 다섯 가지 자세조건 - 나란히 서기, 오른발, 왼발 앞 교차 서기, 오른발, 왼발 앞 직렬 서기 - 에 대하여 각각 1회 65초씩 2회의 수행을 하였다. 압력중심의 복잡성은 시간 공간과 주파수 공간에서 각각 근사 엔트로피와 스펙트럼 기울기에 의해 측정되었고, 가변성은 압력중심의 표준편차에 의해 측정되었다. 압력중심의 복잡성과 가변성 모두 나란히 서기에서 교차서기, 교차서기에서 직렬서기로 갈수록 증가하였다. 대부분의 자세조건에서 왼발과 오른발의 압력중심의 복잡성은 서로 같았으나, 가변성은 나란히 서기 조건을 제외한 모든 조건에서 차이가 나타났다. 연구결과는 복잡성을 통해 시간의 흐름에 따라 발생하는 압력중심의 다이내믹컬한 속성을 분석할 수 있으며 또한 복잡성은 가변성과 상호 독립적인 관계에 있음을 보여준다. The present study investigated complexity of the right, left and total body center of pressure(COP) under several standing conditions using two force platforms. Additional focus was to examine the relation between complexity and variability of the COP. 12 healthy young subjects performed randomly assigned five upright standing conditions, namely side-by-side, staggered with right or left foot forward, and tandem with right or left foot forward. The results revealed that the variability and the complexity of COP<sub>L</sub>, COP<sub>R</sub>, COP<sub>NET</sub> in both time- and frequency-domain progressively increased in the staggered and tandem standings. There was difference in variability between COP<sub>L</sub> and COP<sub>R</sub> for staggered and tandem standing, whereas no difference in complexity between COP<sub>L</sub> and COP<sub>R</sub> across whole standing conditions. The findings suggested that the COP became more irregular in staggered and tandem that refer postural system increased the number of dynamical degrees of freedom to maintain postural stability. Moreover, the study showed that the complexity of COP in the control of upright standing was independent of the variability.
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