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        검색결과 350

        181.
        2008.12 구독 인증기관 무료, 개인회원 유료
        Several lines of evidence suggest that osteocytes play a critical role in bone remodeling. Both healthy and apoptotic osteocytes can send signals to other bone surface cells such as osteoblasts, osteoclasts, osteoclast precursors, and bone lining cells through canalicular networks. Osteocytes responding to mechanical strain may also send signals to other cells. To determine the role for osteocytes an mechanical strain in bone remodeling, we examined the effects of fluid flow shear stress on osteoclast precursor cell and osteoblast proliferation and recruitment induced by osteocytes. In addition, the effects of fluid flow shear stress on osteocyte M-CSF, RANKL, and OPG mRNA expression were also examined. MLO-Y4 cells were used as an in vitro model for osteocytes, RAW 264.7 cells and MOCP-5 cells as osteoclast precursors, and 2T3 cells as osteoblasts. MLO-Y4 cells conditioned medium (Y4-CM) was collected after 24h culture. For fluid flow experiments, MLO-Y4 cells were exposed to 2h of pulsatile fluid flow (PFF) at 2, 4, 8, 16±0.6dynes/cm² using the Flexcell StreamerTM system. For proliferation assays, MOCP-5, RAW 264.7, and 2T3 cells were cultured with control media or 10-100% Y4 CM. Cells were cultured for 3d, and then cells were counted. RAW 264.7 and 2T3 cell migration was assayed using transwells with control media or 10-100% Y4-CM. M-CSF, RANKL and OPG in MLO-Y4 mRNA expression was determined by semiquantitative RT-PCR. Y4-CM increased osteoclast precursor proliferation and migration, but decreased 2T3 cell proliferation and migration. CM from MLO-Y4 cells exposed to PFF caused decreased RAW 267.4 cell proliferation and migration and 2T3 migration compared to control Y4-CM. However, Y4-CM from cells exposed to PFF had no effect on 2T3 osteoblastic cell proliferation. PFF decreased RNAKL mRNA and increased OPG mRNA in MLO-Y4 cells compared to control(without PFF). PFF had no effect on M-CSF mRNA expression in MLO-Y4 cells. These results suggest that osteocytes can regulate bone remodeling by communication with osteoclast precursors and osteoblasts and that osteocytes can communicate mechanical signals to other cells.
        4,000원
        182.
        2008.12 구독 인증기관 무료, 개인회원 유료
        The present study reports the protective properties of a total methanol extract of B. platyphylla var. japonica against ultraviolet (UV)-C irradiation. Pretreatment of Chinese hamster fibroblast (V79-4) cells with a total methanol extract significantly increased cell survival following 300J/m² of UV-C irradiation. The total methanol extract was further fractionated into 5 fractions: n-hexane, dichloromethane, ethylacetate, n-butanol and water fractions. Among these fractions, B. platyphylla var. japonica ethylacetate, butanol and water fractions showed significant protective effects against the cellular damage induced by UV-C irradiation. In order to elucidate the mechanism underlying this protective effect, DPPH (Editor note: abbreviations should be spelled out at first use.) radical scavenging and lipid peroxidation inhibitory activity were measured. Significant radical scavenging and lipid peroxidation inhibitory activities were observed for the ethylacetate fraction. In summary, the present data demonstrate that an extract of B. platyphylla var. japonica has a significant protective effect against UV-C irradiation. The underlying mechanism of this protective effect may involve radical scavenging and inhibition of lipid peroxidation by the B. platyphylla var. japonica extract.
        4,000원
        183.
        2008.12 구독 인증기관 무료, 개인회원 유료
        Inositol 1,4,5-trisphosphate (IP₃) plays an important role in the release of Cα²+ from intracellular stores into the cytoplasm in a variety of cell types. IP₃ translocation dynamics have been studied in response to many types of cell signals. However, the dynamics of cytosolic IP₃ in salivary acinar cells are unclear. A green fluorescent protein (GFP)-tagged pleckstrin homology domain (PHD) was constructed and introduced into a phospholipase C δ1 (PLC δ1) transgenic mouse, and then the salivary acinar cells were isolated. GFP-PHD was heterogeneously localized at the plasma membrane and intracellular organelles in submandibular gland and parotid gland cells. Application of trypsin, a G protein-coupled receptor activator, to the two types of cells caused an increase in GFP fluorescence in the cell cytoplasm. The observed time course of trypsin-evoked IP₃movement in acinar cells was independent of cell polarity, and the fluorescent label showed an immediate increase throughout the cells. These results suggest that GFP-PHD in many tissues of transgenic mice, including non-cultured primary cells, can be used as a model for examination of IP₃intracellular dynamics.
        4,000원
        185.
        2008.09 구독 인증기관 무료, 개인회원 유료
        수평 배향 액정 모드는 양의 유전율 이방성과 음의 유전융 이방성 액정을 사용한 프린지 필드 스위칭과 양의 유전율 이방성 액정을 사용한 인플래인 스위칭 모드가 대표적이다 . 이 대표적인 세 구동 방식의 화질 특성을 비교하기 위하여 각각의 최척화된 위상지연 값 조건하에서 밝기, 명암대비율과 색 특성을 조사하였다. 그 결과 양액정과 음액정을 사용한 프린지 필드 스위칭 모드가 밝기와 명암대비율 면에 있어서 인플래인 스위칭 모드보다 우수한 특성을 보인다. 또한 양액정을 사용한 프린지 필드 스위 칭 모드는 시야각 방향에서 적은 색 변이 특성을 보인다.
        4,000원
        186.
        2008.06 구독 인증기관 무료, 개인회원 유료
        Color is one of the most important attributes determining the purchase of food products by consumers. Therefore, the purpose of this study was to identify consumer color preferences for songpyun, a traditional Korean rice cake, by a consumer acceptance test and using coated Pantone color chips. Color evaluation tools for the study were developed accordingly. From the results, the songpyun sample designated as product E was given the highest color acceptability score, and was ‘slightly liked’ (p<0.05). The color of product E was ‘very pale red-purple’. All the evaluated pink-color songpyun products were based on this red-purple hue, however, they had differences in tone. The consumer panel favored a pale tone over a bright tone. The color concept for traditional songpyun within the pink color category was identified as ‘very pale red-purple’, using coated Pantone color chips. This result for the conceptual color preference was consistent with that of the consumer color acceptance test. Thus, color chips could be an effective tool when applied for color standardization in traditional foods production. From the overall results, it seems consumers are perceiving color trends and are willing to adapt to such changes in food applications.
        4,000원
        190.
        2007.12 구독 인증기관 무료, 개인회원 유료
        Field sequential 액정 디스플레이(FSLCD)는 컬러필터를 사용하지 않아 높은 투과율 특성을 보이고 광 원으로 LED를 사용함으로써 색재현성이 매우 우수하다. 하지만 FSLCD(60Hz 구동)를 실현하기 위해서는 액정의 응답속도가 5ms이하로 고속응답 특성을 보여야 한다. 따라서 본 논문에서는 고속응답 ECB(electrically controlled birefringence) 셀의 최적 구조를 연구하여 5ms 이하의 응답시간을 얻었다. 그리고 ECB 모드에서 높은 구동전압과 시야각을 개선하기 위해 필름 보상을 연구하였다. 판상형 액정필름(discotic film)과 TAC(triacetyl cellulose) 필름의 위상차 값을 최적화함으로써 구동전압을 5V로 낮추고 상하좌우에서 160° 이상(CR>10:1)의 시야각을 실현하였다.
        4,000원
        191.
        2007.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        분리층 두께가 5 μm이며 Si/Al 몰비가 1.5인 Na형 faujasite 제올라이트 분리막을 이차성장 공정에 의하여 제조하였고, 투과부에 13X 제올라이트 흡착제 충진 전후의 진공모드에서의 CO2/N2 분리거동을 CO2/N2 몰비가 1인 혼합기체에 대하여 30℃에서 평가하였다. 충진된 13X 제올라이트 흡착제는 CO2 투과도와 CO2/N2 선택도를 동시에 증진시켰다. 이 현상은 13X 제올라이트 흡착제 충진이 다공성 α-알루미나 지지체의 기공채널을 통한 CO2 탈출을 증진시킴으로써 faujasite 제올라이트/α-알루미나 상계면에서의 CO2 탈착을 증진시켰기 때문으로 설명되었다. 본 논문으로부터 흡착제와 분리막의 혼성화는 일반적으로 보여지는 선택도와 투과도의 역비례 관계를 획기적으로 개선할 방법임이 확인되었다.
        4,000원
        196.
        2006.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        5,700원
        197.
        2006.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Immuno-MemBlot is a technique for detecting, analyzing, and identifying proteins, similar to the Western blot technique but differing in that protein samples are not separated electrophoretically but are spotted through circular or slot templates directly onto the membrane. Recently we developed a new Immuno-MemBlot (IMB) method applying immunoreactions and coloring procedures directly in the wells of MemBlot apparatus, which were connected by canals to perform drainage for reagent application and buffer irrigation. This IMB method was designed to get theimmunoblot results more rapidly and clearly than the previous immunoblot ones. This study is aimed to evaluate the analytical accuracy of IMB using different biological assay. In the sensitivity test of IMB the monoclonal antibody can clearly detect the 30 ng (about 12 pM) of Mucocidin peptide (35 mer), and is also available to detect at least 10 ng (about 4 pM) of Mucocidin peptide (35 mer). The IMB was effective in the quantitative analysis of methothrexate (MTX) assay for cellular apoptosis. And more, this IMB is useful to screen large number of specific samples with ease and accuracy in a short time. In the screenings for the presence of Mucocidin in saliva the quantitative comparison is conspicuous among 48 persons depend on the different conditions ofgender, drinking and smoking habits, and oral diseases. Therefore, it is presumed that, even though the target proteins were partly degraded, a specific epitope can be detected if a monoclonal antibody was still reactive. Conclusively, these data suggest that the IMB can be useful in the primary qualitativeand quantitative analysis of proteins in various fluids, i.e., blood, saliva, tear, urine, etc.
        4,200원
        199.
        2005.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 논문에서 사고로 누출된 삼중수소에 의한 농작물 오염평가 모델을 제시한다. 본 논문에서 제시된 모델은 동적격실모델로써 작물의 성장 방정식을 도입한 것이 특징이며, 이로부터 삼중수소 피폭시 작물의 성장단계에 따른 오염 정도를 예측할 수 있다. 시스템은 크게 대기, 토양, 작물격실로 구성되며, 격실의 삼중수소 농도 변화는 비선형 상미분방정식으로 표현되므로 시간에 따른 각 격실의 삼중수소 농도가 계산된다. 모델의 검증을 위해 배추 및 무에 대한 삼중수소 피폭 실험을 수행하였다. 생육단계별 오염 효과를 조사하기 위해 각기 다른 생육단계에 있는 배추와 무를 독립적으로 HTO 증기에 노출시켰으며, 피폭 후 오염된 작물의 tissue free water tritium(TFWT) 및 organically bound tritium(OBT) 농도를 측정하였다. 측정된 작물 부위별 삼중수소 농도 데이터와 모델 예측 값은 대체로 잘 일치하였다.
        4,000원