• Development and Reproduction
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• v.15 no.4
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• pp.273-279
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• 2011

Epigenetic regulation is a phenomenon that changes the gene function without changing the underlying DNA sequences. Epigenetic status of chromosome is regulated by mechanisms such as histone modification, DNA modification, and RNAi silencing. In this review, we focused on histone methylation for epigenetic regulation in ES cells. Two antagonizing multiprotein complexes regulate methylation of histones to guide expression of genes in ES cells. The Polycomb repressive complex 2 (PRC2), including EED, EZH2, and SUZ12 as core factors, contributes to gene repression by increasing trimethylation of H3K27 (H3K27me3). In contrast, the Trithorax group (TrxG) complex including MLL is related to gene activation by making H3K4me3. PRC2 and TrxG accompany a variety of accessory proteins. Most prominent feature of epigenetic regulation in ES cells is a bivalent state in which H3K27me3 and H3K4me3 appear simultaneously. Concerted regulation of PRC2, TrxG complex, and H3K4- or H3K27-specific demethylases activate expression of pluripotency-related genes and suppress development-related genes in ES cells. Modified balance of the regulators also enables ES cells to efficiently differentiate to a variety of cells upon differentiating signals. More detailed insights on the epigenetic regulators and their action will lead us to better understanding and use of ES cells for future application.

• Journal of Life Science
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• v.33 no.10
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• pp.767-775
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• 2023

Sulfasalazine is a disease-modifying antirheumatic abiotic agent. It is a derivative of aminosalicylic acid and has been used for the treatment of various inflammatory diseases, such as rheumatoid arthritis, ulcerative colitis, and Crohn's disease, since it was first synthesized in 1941 and approved as a medicine in the United States in 1950. However, its mechanism of action has not yet been clearly identified. In this study, the effects of sulfasalazine on cell survival, apoptosis, and cell cycle progression in macrophages, which are major immune cells that regulate inflammatory responses, were investigated using mouse macrophage RAW 264.7 cells. Sulfasalazine inhibited the viability of RAW 264.7 cells in a dose-dependent manner, starting at a concentration of 0.25 mM. Annexin-V staining was used to confirm that the decrease in cell viability was due to apoptosis, and the number of Annexin-V-positive cells increased significantly at a concentration of 0.25 mM or higher. The effect of sulfasalazine on the expression of key proteins that regulate the G0/G1 phase of the cell cycle was also investigated. Sulfasalazine treatment significantly increased the expression of the cyclin-dependent kinase inhibitors p21 and p27 in RAW 264.7 cells. Although sulfasalazine is frequently used as a control drug in studies on inflammatory diseases, such as inflammatory colitis and rheumatoid arthritis, studies on its effect on macrophages are very limited. Therefore, the results of this study are expected to provide vital information on the use of sulfasalazine as a disease treatment.

• Journal of Chest Surgery
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• v.39 no.1 s.258
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• pp.1-11
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• 2006

Background: CD44 is a glycoprotein on the cell surface which is involved in the cell-to-cell and cell-to-matrix interaction. The standard form, CD44s and multiple isoforms are determined by alternative splicing of 10 exons. Recent studies have suggested that CD44 may help invasion and metastasis of various epithelial tumors as well as activation of Iymphocytes and monocytes. The expression pattern of CD44 can be different according to tumor types. The author studied the expression pattern of CD44s and one of its variants, CD44v6 in non-small cell lung carcinomas (NSCLC) to find their implications on clinicopathologic aspects, including the survival of the patients. Material and Method: A total of 89 primary NSCLSs (48 squamous cell carcinomas, 33 adenocarcinomas, and 8 undifferentiated large cell carcinomas) were retrieved during the years between 1985 to 1994. The immunohisto chemistry was done by using monoclonal antibodies and the CD44 expression for angiogenesis was evaluated by counting the number of tumor microvessels. Result: Seventy-one (79.8$\%$) and 64 (71 .9$\%$) among 89 NSCLSs revealed the expression of CD44s and CD44v6, respectively. The expression of CD44s was well correlated with that of CD44v6 (r=0.710, p < 0.0001). The expression of CD44s and CD44v6 was associated with the histopathologic type of the NSCLCs, and squamous cell carcinoma was the type that showed the highest expression of CD44s and CD44v6 (p < 0.0001). Microvessel count was the highest in adenocarcinomas (113.6$\pm$69.7 on 200-fold magnification and 54.8$\pm$41.1 on 400-fold magnification) and correlated with the tumor size of TNM system (r=0.217, p=0.043) and CD44s expression (r=0.218, p=0.040). In adenocarcinoma, the patients with higher CD44s expression survived shorter than those with lower CD44s expression (p=0.0194) but there was no statistical significance on multivariate analysis(p=0.3298). Conclusion: The expression of both CD44s and CD44v6 may be associated with the squamous differentiation in non-small cell lung carcinomas. The relationship of CD44s expression with micro-vessel density of the tumor suggests an involvement of CD44s in tumor angiogenesis, which in turn would help tumor growth.

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.130-136
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• 1998

An Immunostimulating polysaccharide was produced from the suspension culture of Angelica gigas H4, plant cells. In order to enhance the polysaccharide production by the A. gigas cell culture, medium composition and physical conditions were optimized. Schenk and Hildebrandt (SH) medium was selected as an optimal basal medium for the growth of A. gigas. The maximum cell and polysaccharide concentration obtained in SH medium were 15.8 g DCW/l and 0.85 g polysaccharide/l, respectively, at $25^{\circ}C$ under dark condition. For the enhanced polysaccharide production, a polysaccharide production medium (PPM) was established by modifying Gamborg B5 medium with optimized carbon sources, growth regulators, organic and inorganic elements. Optimal initial pH and temperature were 6.0-6.6 and $20^{\circ}C$, respectively, and the dark condition was better than the light condition. The maximum polysaccharide concentration of 1.5 g/l could be obtained through the optimization of the medium composition and physical conditions.

• The Journal of Korean Society of Virology
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• v.26 no.1
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• pp.23-30
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• 1996

대략 36,000 base pairs (bp)의 두 가닥짜리 DNA를 지놈으로 가진 사람 아데노바이러스 (Ad)는 DNA 상동성(相同性) 및 생물학적/생화학적 성격이 특이한 49개의 혈청형이 알려져 있는데, 이들 대부분의 Ad가 영유아군 및 면역능이 저하된 성인에서 치사적 결과를 초래할 수 있다. Ad의 세포향성(向性)(tropism)은 매우 다양하여 종류에 따라 상기도 감염, 각결막염, 영유아 장염등을 유발하는데 최근 Ad의 다양한 병원성에 대한 원인을 분자생물학적 수준에서 규명하려는 노력의 일환으로 지역에 따라 주되게 출현하는 Ad형 규명이 활발히 이루어지고 있다. Ad 동정/확인은 표면을 이루고 있는 group 공통항원인 hexon 단백질을 탐지하는 효소면역 측정법 (EIA)에 의하며, Ad형별은 Ad fiber의 세포독성 중화시험에의 한다. 그러나, 세포독성 중화시험이 엄청난 노동력 및 시간을 요구하면서도 민감도/특이도가 만족스럽지 못하여 이를 개선하기 위하여 검체 또는 세포배양에서 Ad DNA를 추출하여 제한효소 절단형태를 비교하는 방법이 개발되었는데 이는 세포배양에 잘 자라지 않는 바이러스주의 형별뿐만 아니라 지역 분리주들의 지놈 변형주를 관찰하는 분자생물학적/분자역학적 연구에도 도움이 되고 있다. 국내에는 Ad와 관련된 소아장염의 빈도가 rotavirus에 의한 것 다음으로 빈번한데도 Ad40/41외에 주되게 출현하는 장내 Ad형들이 전혀 규명된 바 없고, 한국형 Ad들의 지놈형태가 전혀 보고된 바가 없다. 또한 세계적으로 Ad형별 조사지역이 늘어감에 따라 유아장염과 연관된 Ad 역시 Ad40, 41이 외의 형들이 Ad40, 41을 능가하는 것으로 보고되고 있는 지역도 있으나 국내에서는 Ad40, 41이외의 형들은 그 역학적 중요도가 전혀 알려져 있지 않다. 이로서 본 연구의 목적은 Ad주들에 특이 중화항체를 이용한 세포독성 중화시험과 Ad DNA 절단법을 적용하여 한국형 장내 Ad주들의 형별을 처음으로 시도함과 동시에 1989-1991사이 출현한 Ad들의 유전적 변형을 관찰하려는 것이었다. 두 방법 모두 사용하였을 때 주되게 출현하는 장내 Ad형들은 Ad4l, Ad2, Ad7, Ad5, 및 Ad40이었다. Ad40/41-양성 검체를 제외한 Ad hexon-EIA양성들의 77.5%를 형별 할 수 있었던 Ad DNA의 제한효소 절단방법은 형들간의 교차중화로 특이성이 낮았던 중화방법 (47.5%)보다 매우 효율적이어서 두 가지 방법을 함께 적응하였을 때는 40주중의 81.5%인 35주를 형별 할 수 있었다. 또한Ad DNA 제한 효소 절단방법은 Ad7 변이주 (Ad7b)도 탐지 할 수 있었다.

• Childhood Kidney Diseases
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• v.16 no.1
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• pp.21-31
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• 2012

Focal segmental glomerulosclerosis (FSGS) is the name of the primary glomerular disease as well as the terminology to describe the secondary phenomena of any other glomerular diseases. It is characterized by sclerosis, hyalinosis, foam cell infiltration, vacuolar change of podocytes, and halo formation in the glomerulus. Throughout the interstitium, lymphocytes infiltration, tubular atrophy and vascular changes are accompanied. Occasionally, IgM and/or C3 depositions are noted in the sclerotic areas. Electron microscopically, diffuse effacement of foot processes are seen in non-sclerotic area like minimal change disease. Podocyte injury patterns including vacuolar changes are frequently examined. Recently, Columbia group has suggested morphologic classification of FSGS and they demonstrated very good prognosis of tip lesion and poor prognosis of both collapsing and cellular types. However, the pathogenetic classification has been suggested by others; hyperfilteration, podocyte injury, genetic lesions etc. Further studies are necessary to understand and treat this disease.

• KSBB Journal
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• v.24 no.3
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• pp.217-226
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• 2009

p53 undergoes various post-translational modifications, including phosphorylation, ubiquitination, sumoylation, acetylation, methylation, and poly(ADP-ribosyl)ation. Modification of p53 widely affects to various functions of p53. Acetylation and phosphorylation of p53 have been studied for regulating its transcriptional activity which is observed in various stress condition. Otherwise, ubiquitination of p53 by Mdm2 has been well-studied as a canonical ubiquitin-mediated proteasomal degradation pathway. Moreover several investigators have recently reported that ubiquitination of p53 modulates not only its proteasome-dependent degradation by poly-ubiquitination but also its localization and transcriptional activity by mono-ubiquitination which usually does not serve the proteasome dependent degradation. Here we review recent studies on the cellular functions of p53 regulated by post-translational modifications, particularly focusing on mechanisms of ubiquitination.

• Proceedings of the KSMRM Conference
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• 2003.10a
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• pp.36-36
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• 2003

목적： 고형성 종양에 특이적으로 발현하는 MR 분자영상용 조영제의 후보물질을 분자생물학적 방법 및 in vitro 분자영상기법을 이용하여 탐색하고자 하였다. 대상 및 방법： 암이 진행됨에 따라 유전자가 과발현되는 세포표면 단백질인 CD44 와 세포막에 존재하는 단백질분해효소의 일종인 MTI-MMP를 일차 선정하여 유전자 수준 및 단백질 수준에서 분자생물학적 방법으로 종양특이성에 대해 검증하였고, 특히 각종 암세포에서 발현양이 증가하는 CD44의 변형인 CD44v6 항체를 이용하여 생세포에서의 표적화에 대한 광학적 검증을 위해 초상자성 나노입자 대신 형광입자(FITC)를 결합하여 confocal microscopy로 실시간 표적화에 대한 분자영상을 획득하였다.

• Journal of Life Science
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• v.25 no.6
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• pp.724-731
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• 2015

Mesenchymal stem cells (MSCs) are characterized by their multipotency capacity, which allows them to differentiate into diverse cell types (bone, cartilage, fat, tendon, and neuron-like cells) and secrete a variety of trophic factors (ANG, FGF-2, HGF, IGF-1, PIGF, SDF-1α, TGF-β, and VEGF). MSCs can be easily isolated from human bone-marrow, fat, and umbilical-cord tissues. These features indicate that MSCs might be of use in stem-cell therapy. However, MSCs undergo cellular senescence during long-term expansion, and this is accompanied by functional declines in stem-cell potency. In the human body, because of their senescence and declines in their microenvironmental niches stem cells fail to maintain tissue homeostasis, and as a result, senescent cells accumulate in tissues. This can lead to age-related diseases, including degenerative disorders and cancers. Recent studies suggest that the number of histone modifications to stem cells’ genomes and aberrant alterations to their DNA methylation increase as stem cells progress into senescence. These epigenetic alterations have been partly reversed with treatments in which DNA methyltransferase (DNMT) inhibitors or histone deacetylase (HDAC) inhibitors are introduced into replicative senescent-MSCs. This review focuses on epigenetic alteration in replicative senescent-MSCs and explains how epigenetic modifications are widely associated with stem-cell senescences such as differentiation, proliferation, migration, calcium signaling, and apoptosis.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.3
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• pp.78-87
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• 1994

생물학 및 의학등의 생명과학에서는 현미경을 이용하여 생체물질 즉, 생체조직을 관찰하고 이에 대한 조직의 검사 결과를 판정하고 발표한다. 이때 필히 고정과정(fixation process)을 거쳐야 한 다. 즉, 생체조직중 조직의 구조, 특정 세포나 바이러스 및 효소등을 관찰할 때 고정과정을 거쳐 조직을 절편하고 이를 염색하여 현미경으로 검사하게 된다. 고정과정이란 생체물질을 안정화시키고 자기분해 혹은 부패를 방지하여 보존이 가능하도록 변화시키 는 과정으로, 조직내의 용해성 물질을 불용성 물질로 변형시키는 과정이다. 고정과정을 거친 생체조직 은 구조를 보존하고 있기 때문에 조직의 훼손이 없는 상태에서 절편이 가능하고 또한 염색상태를 좋게 하며 관찰시 contrast를 증진시킨다. 만약 고정과정을 거치지 않으면 물질의 세포막이 파괴되고 단백질 등의 물질이 용해되어 조직의 변형을 일으켜 제대로 조직을 관찰할 수 없게 된다. 고정과정에는 크게 화학적 고정법과 물리적 고정법이 있다. 화학적 고정법은 생체조직을 화학용액에 처리하는 방법이며, 물리적 고정법은 직접적인 열 혹은 초음파등으로 물질을 고정시키는 방법이다. 표 면과 내부의 열전도가 달라져 고정이 균일하게 되지 않는 단점을 가지고 있기 때문에 보통 2~6일의 고 정시간을 요하는 화학적 고정법을 사용하고 있다. 따라서 조직에 대한 총 검사시간이 최소 6일에서 최 대 12일이 요구된다. 병원등에서 조직검사의 결과가 늦게 발표되는 사유는 바로 화학적 고정법을 사용 하여 생체조직을 관찰하고 그 결과를 판정하기 때문이다. 본 고에서는 마이크로파를 이용하여 약 3시간만에 조직의 상태를 관찰할 수 있는 고정법을 소개한다. 마이크로파를 이용하여 조직을 고정하는 고정방법을 기존의 고정법과 비교하여 이들의 장단점을 나타 낸다. 본 연구자에 의해 개발된 마이크로파 고정기를 소개하고, 이를 이용하여 생체물질을 고정한뒤 절 편, 염색하여 현미경 관찰결과를 발표하여 본 연구의 방법이 기존 방법보다 우수함을 나타낸다.