• 대한치과보철학회지
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• 제42권3호
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• pp.307-326
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• 2004

Statement of problem. The long-term success of implants is the development of a stable direct connection between bone and implant surface, which must be structural and functional. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. Among them, altering the surface properties can modify cellular responses such as cell adhesion, cell motility and bone deposition. Purpose. This study was to evaluate the cellular behaviors on the surface-modified titanium by morphological observation, cellular proliferation and differentiation. Material and methods. Specimens were divided into five groups, depending on their surface treatment: electropolishing(EP) anoclizing(AN), machining(MA), blasting with hydroxyapatite particle(RBM) and electrical discharge machining(EDM). Physicochemical properties and microstructures of the specimens were examined and the responses of osteoblast-like cells were investigated. The microtopography of specimens was observed by scanning electron microscopy(SEM). Surface roughness was measured by a three-dimensional roughness measuring system. The microstructure was analyzed by X-ray diffractometer(XRD) and scanning auger electron microscopy(AES). To evaluate cellular responses to modified titanium surfaces, osteoblasts isolated from neonatal rat were cultured. The cellular morphology and total protein amounts of osteoblast-like cell were taken as the marker for cellular proliferation, while the expression of alkaline phosphatase was used as the early differentiation marker for osteoblast. In addition, the type I collagen production was determined to be a reliable indicator of bone matrix synthesis. Results. 1. Each prepared specimen showed specific microtopography at SEM examination. The RBM group had a rough and irregular pattern with reticulated appearance. The EDM-treated surface had evident cracks and was heterogeneous consisting of broad sheet or plate with smooth edges and clusters of small grains, deep pores or craters. 2. Surface roughness values were, from the lowest to the highest, electropolished group, anodized group, machined group, RBM group and EDM group. 3. All groups showed amorphous structures. Especially anodized group was found to have increased surface oxide thickness and EDM group had titaniumcarbide(TiC) structure. 4. Cells on electropolished, anodized and machined surfaces developed flattened cell shape and cells on RBM appeared spherical and EDM showed both. After 14 days, the cells cultured from all groups were formed to be confluent and exhibited multilayer proliferation, often overlapped or stratified. 5. Total protein amounts were formed to be quite similar among all the group at 48 hours. At 14 days, the electropolished group and the anodized group induced more total protein amount than the RBM group(P<.05). 6. There was no significant difference among five groups for alkaline phosphatase(ALP) activity at 48 hours. The AN group showed significantly higher ALP activity than any other groups at 14 days(P<.05). 7. All the groups showed similar collagen synthesis except the EDM group. The amount of collagen on the electropolished and anodized surfaces were higher than that on the EDM surface(P<.05).

• 문화기술의 융합
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• 제7권4호
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• pp.721-726
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• 2021

식물 세포는 각 세포가 발생을 통해 새로운 완전한 개체를 생산하는 전형성능이 있다. 이것을 응용하여 식물의 증식 방법으로 기내에서 호르몬을 처리하여 체세포 배 발생의 광범위한 적용으로 여러 기술이 발전하고 있다. 이 기술을 이용하기 위해서 보다 규칙적인 세포 분열을 하는 무성생식이 가능한 식물인 Kalanchoe pinnata 에 cytokinin에 속하는 kinetin과 auxin에 속하는 호르몬들 중 picloram을 서로 조합하여 첨가한 뒤 8주 동안 처리한 후 전형성능을 실험하였다. 우리의 실험 결과로 잎 절편에서 발근 효과로는 picloram 농도가 0.1 mg/L에서 70%의 발생율을 보였다. kinetin과 picloram의 비율이 1:5-1:10의 농도차이가 효과적이라는 것이 입증 되었다. auxin의 효과가 Kalanchoe 뿌리 발생에 필수적이라는 실험 결과이다. 경엽부 발생 효과로는 picloram 농도가 0.5 mg/L에서 60%의 발생율을 보였다. kinetin 농도는 0.5 - 1.0 mg/L이며 발생에 중요한 영향을 준다. kinetin과 picloram의 비율이 1:1-1:2의 농도 차이가 효과적이라는 것이 입증 되었다. cytokinin과 auxin의 조합이 결정적으로 경엽부 발생에 중요하다는 것을 보여 주는 결과이다. 호르몬의 조합으로 직접기관형성을 유도하여 기내에서 대량 증식을 유도하는 기술의 기초가 될 수 있다고 사료된다.

• 한국가금학회지
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• 제20권4호
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• pp.177-188
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• 1993

닭에서 적절한 성감별 방법을 개발하고 닭의 성분화 기작의 기초자료를 얻기 위하여 배아의 섬유아세포의 염색체를 분석하고, W 염색체 특이적인 반복염기서열과 50∼60％의 유사성을 보이는 random primer로 PCR 증폭을 실시하여 성을 판별하는 방법이 이용되었으며, 닭에서 성분화에 관련된 유전자를 분리하기 위해 W 염색체 특이적인 반복염기서열을 클로닝하였고, PCR을 이용하여 ZFY와 SRY 염기서열을 증폭하였다. 닭의 배아섬유세포의 염색체 분석 결과 Z 염색체와 W 염색체를 구분함으로써 배아의 성을 직접적으로 판별하는 것이 가능하였으며 , 암닭의 DNA를 Xho Ⅰ와 Eco RI로 절단하여 생성되는 band를 이용하여 성을 판별하는 것이 가능하였다. Xho Ⅰ와 Eco RI family를 클로닝하고, colony hybridization을 통해 Xho Ⅰ과 염기서열이 유사한 80∼100개의 clone을 동정하여, 이들 두 그룹간 DNA homology는 매우 유사하였다. 150개의 random primer 중 W 염색체 특이적인 반복 염기서열과 유사성을 보이는 primer 7개를 screening하였으며, 이 중 3개의 primer는 닭에서 자성과 웅성간의 차이를 나타내었다. 닭에서 성분화에 관련된 유전자를 동정하기 위하여 포유류의 ZFY와 SRY유전자의 PCR증폭을 실시하였다. ZFY를 증폭한 결과, 자성과 웅성간의 차이를 발견할 수 없었으며, 이는 닭에서 ZFY는 상염색체 또는 Z 염색체에 존재함을 시사한다. SRY의 증폭에서는 성간의 차이가 확인되었으나, 이 유전자가 Z 염색체에 존재하는지 W 염색체에 존재하는지 혹은 상염색체 존재하는지 여부는 연구가 필요하리라 사료된다.

• 한국임상수의학회지
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• 제28권4호
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• pp.394-398
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• 2011

Mesenchymal stem cells (MSC) are pluripotent cells that can be found in umbilical cord blood from new borne babies as well as placenta, bone marrow, adipose tissue, amniotic fluid, muscle, et al. MSC are capable of renewing themselves without differentiation in long-term culture, also can be differentiated into various tissues under specific condition. Formulating a cryopreservation protocol for the MSC is required because these cells cannot survive for long periods under in vitro culture conditions and a new formulation of harmless cryoprotectant is needed for the direct injection of MSC into patients. The undifferentiated MSC were frozen with a vitrification solution of 40% ethylene glycol, 20% Ficoll-70 and 0.3M sucrose. The survival rate after thawing and their proliferation rate were examined and compared with slow rate cooling methods using dimethylsulfoxide (DMSO). The vitrification method showed high survival rate after thawing and proliferation capacity comparable to DMSO. It can be suggested that ultra-rapid cooling method by vitrification is reliable methods for long term preservation of MSC and the vitrification solution with ethylene glycol, Ficoll-70 and sucrose will be more beneficially used for direct transplantation of MSC into patients than DMSO solution.

• 한국콘텐츠학회논문지
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• 제7권12호
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• pp.66-73
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• 2007

주얼리 관련 산업은 국내 시장의 불황, 디자인 개발 부재, 기능 인력의 부재와 높은 인건비 부담으로 고민에 처해 있다. 또한 소비자들의 가격대비 최대한의 가치를 가진 차별화된 제품을 원하고 있다. 주얼리 CAD와 RP 장비는 수작업에 의존했던 주얼리 제조업체에게 생산성을 단축시켜주고 다양한 디자인과 빠른 신제품을 제공해 줄 수 있다. 하지만 아직까지 RP에서 출력된 합성 수지의 직접 주조의 어려움으로 원본 작업에 필요한 만큼의 최상의 주조 소환 사이클을 알지 못하는 상태이다. 이에 본 연구자는 CAD의 활용성과 RP 장비에 관하여 분석하고, 주얼리 CAD 작업과 RP 작업을 통하여 직접 주조가 가능하도록 주조 소환 사이클을 분석하여 원본 제작에 적합한 제품을 제작할 수 있었다. 이 논문을 통해 주얼리 제품의 질적 향상과 차별성을 확보하여 다양하고 경쟁력 있는 디자인과 제품 생산에 새로운 기반을 제공하는 것에 의의를 찾고자 한다.

• Journal of Plant Biotechnology
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• 제7권3호
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• pp.161-167
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• 2005

Brassinosteroids are steroidal plant hormones and are known to modulate physiological and cellular response in a wide range of plant species. Considerable insights has been achieved of the physiological role of brassinosteroid in Brassica species in the past few years, but their effect on direct organogenesis has not been extensively studied. In this sense, under optimal basal media and growth conditions we tested the cellular and organogenic response of 24-epibrassinolide (EBL) in a variable concentration (0.1 to $5.0\;{\mu}M$) and Zeatin (Z) (1.0 to $100\;{\mu}M$) and their synergic effect on hypocotyl explants of cauliflower and broccoli. The isolated EBL accelerated cell elongation and promotes direct organogenesis. One micromolar EBL + $10\;{\mu}M$ of Z was the most efficient combination for cell elongation, cell differentiation as well as for organogenesis. A suppressing effect on root induction was confirmed for all the tested hormone levels. The general results indicate a synergic effect of EBL-Z and EBL potentates Zeatin activity, at least in certain tissues. Besides de genetic factors, we can speculate that the natural hormone concentration in the explants might affect the responses by application of exogenous growth regulators. Experiments with new plant growth regulators, like brassinolide, are important aiming to maximize or accelerate plant regeneration for in vitro multiplication or for genetic transformation.

• Archives of Pharmacal Research
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• 제20권2호
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• pp.128-137
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• 1997

The effects of cylindan, a polysaccharide isolated from the basidiocarps of Agrocybe cylindracea, on murine sarcoma 180 tumor and murine immune cells were examined after intraperitoneal administration. Cylindan exhibited a marked life extension effect in mice against ascite forms of sarcoma 180 and Lewis lung carcinoma at a dose of 50 mg/kg/day, although it did not show any direct cytotoxicity against sarcoma 180, X5563, and MM46 murine tumor cells. Cylindan increased numbers of bone marrow stem cells as well as peritoneal exudate cells in flow cytometry using monoclonal antibodies. The tumor bearing mice group apparently showed the increase of macrophages and cytotoxic T lymphocytes in mouse spleen cells during the early stage of tumor growth. But during the later stage, the control group decreased immune cells and cylindan restored the decreased immune cells in the tumor bearing mice to the normal level. In non-specific immune response, cylindan stimulated the bacterial phagocytosis and acid phosphatase production in macrophages. It also activated components of the alternative complement pathway and natural killer activity against YAC-1 lymphoma. In number of plasma cells as token of stimulation of the differentiation of B lymphocytes. In cellular immunity, cylindan restored the depressed response of delayed type hypersensitivity in the tumor bearing mice to 60% of the normal level and increased the interleukin-2 (IL-2) responsiveness in the IL-2 dependent CTLL-2 cells. These results suggest that cylindan did not show direct cytotoxic effects on tumor cells but restored the decreased immune response of the tumor bearing mice.

• Molecules and Cells
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• 제45권10호
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• pp.695-701
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• 2022

Homeostatic regulation of meristematic stem cells accomplished by maintaining a balance between stem cell self-renewal and differentiation is critical for proper plant growth and development. The quiescent center (QC) regulates root apical meristem homeostasis by maintaining stem cell fate during plant root development. Cell cycle checkpoints, such as anaphase promoting complex/cyclosome/cell cycle switch 52 A2 (APC/C^CCS52A2), strictly control the low proliferation rate of QC cells. Although APC/C^CCS52A2 plays a critical role in maintaining QC cell division, the molecular mechanism that regulates its activity remains largely unknown. Here, we identified SCF^FBS1, a ubiquitin E3 ligase, as a key regulator of QC cell division through the direct proteolysis of CCS52A2. FBS1 activity is positively associated with QC cell division and CCS52A2 proteolysis. FBS1 overexpression or ccs52a2-1 knockout consistently resulted in abnormal root development, characterized by root growth inhibition and low mitotic activity in the meristematic zone. Loss-of-function mutation of FBS1, on the other hand, resulted in low QC cell division, extremely low WOX5 expression, and rapid root growth. The 26S proteasome-mediated degradation of CCS52A2 was facilitated by its direct interaction with FBS1. The FBS1 genetically interacted with APC/C^CCS52A2-ERF115-PSKR1 signaling module for QC division. Thus, our findings establish SCF^FBS1-mediated CCS52A2 proteolysis as the molecular mechanism for controlling QC cell division in plants.

• Biomolecules & Therapeutics
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• 제31권3호
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• pp.264-275
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• 2023

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by tremors, bradykinesia, and rigidity. PD is caused by loss of dopaminergic (DA) neurons in the midbrain substantia nigra (SN) and therefore, replenishment of DA neurons via stem cell-based therapy is a potential treatment option. Astrocytes are the most abundant non-neuronal cells in the central nervous system and are promising candidates for reprogramming into neuronal cells because they share a common origin with neurons. The ability of neural progenitor cells (NPCs) to proliferate and differentiate may overcome the limitations of the reduced viability and function of transplanted cells after cell replacement therapy. Achaete-scute complex homolog-like 1 (Ascl1) is a well-known neuronal-specific factor that induces various cell types such as human and mouse astrocytes and fibroblasts to differentiate into neurons. Nurr1 is involved in the differentiation and maintenance of DA neurons, and decreased Nurr1 expression is known to be a major risk factor for PD. Previous studies have shown that direct conversion of astrocytes into DA neurons and NPCs can be induced by overexpression of Ascl1 and Nurr1 and additional transcription factors genes such as superoxide dismutase 1 and SRY-box 2. Here, we demonstrate that astrocytes isolated from the ventral midbrain, the origin of SN DA neurons, can be effectively converted into DA neurons and NPCs with enhanced viability. In addition, when these NPCs are inducted to differentiate, they exhibit key characteristics of DA neurons. Thus, direct conversion of midbrain astrocytes is a possible cell therapy strategy to treat neurodegenerative diseases.

• 벤처창업연구
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• 제14권6호
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• pp.29-43
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• 2019

본 연구에서는 국가경제와 일자리 창출에 중요한 역할을 수행하고 있는 벤처기업의 생존 및 발전에 시사점을 제시하고자 벤처기업 창업가의 특성과 경영성과와의 관계에 경영전략을 매개변수로 하여 실증분석을 하였다. 기존의 국내 선행연구들이 창업가의 특성과 경영전략을 경영성과에 대한 동일한 단일차원의 함수관계로 분석하는데서 벗어나서, 창업가의 특성을 독립변수로, 기업차원의 경영전략을 매개변수로 하여 다차원적인 관점에서 기업의 경영성과를 설명하려고 하였다. 분석결과는 첫째, 벤처 창업가의 특성은 경영성과에 정(+)의 영향을 미치는 것으로 나타났다. 특히, 창업가의 특성 중에서도 진취성이 경영성과에 미치는 영향력이 가장 큰 변수로 확인되었다. 반면, 위험감수성은 그 영향력이 상대적으로 매우 미미한 수준으로 분석되었다. 둘째, 벤처 창업가의 특성은 경영전략에 정(+)의 영향을 미치는 것으로 나타났다. 특히, 창업가 특성 중에서 혁신성은 기술혁신 차별화 전략에, 진취성은 마케팅 차별화 전략에 가장 큰 영향을 주는 중요한 변수로 분석되었다. 셋째, 벤처기업의 경영전략은 경영성과에 정(+)의 영향을 미치는 것으로 나타났다. 특히, 경영전략 중에서도 기술혁신 차별화 전략이 마케팅 차별화 전략에 비해 경영성과에 미치는 영향력이 큰 것으로 분석되었다. 넷째, 벤처 창업가의 특성과 경영성과와의 관계에서 경영전략은 부분 매개효과가 있는 것으로 나타났다. 즉, 창업가의 특성은 경영성과에 직접적인 영향을 미치기도 하지만 경영전략과 매개되어 경영성과에 간접적인 영향을 미치는 것으로 밝혀졌다. 이런 연구결과는 벤처기업 창업가의 개인적인 특성과 기업차원의 경영전략이 연계되었을 때 더 극대화된 경영성과를 이룰 수 있다는 것을 시사해준다.