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        검색결과 147

        61.
        2010.12 KCI 등재 구독 인증기관·개인회원 무료
        Neurotrophic factors are essential to maintain and organize neurons functionally; thereby neurotrophic factor-like substances or their inducers are expected to be applied to the treatment of neurodegenerative diseases such as stroke. In the present study, we firstly examined the effects of ethanol extracts of Hericium erinaceus (HE, Yamabushitake), on nerve growth factor expression in neuronal cells. HE extract promoted NGF expression in a brain tissue. Here we assessed neuroprotective effects of HE with a transient global cerebral ischemia model. Global cerebral ischemia was induced by occluding both common carotid arteries. Treatment with HE was initiated after ischemia induction and given once a day for 7 consecutive days. Neuronal cell loss in CA1 of hippocampus was significantly decreased and the performance in the Morris water maze was significantly improved in rats administered HE. We conclude that treatment with HE attenuated learning and memory deficits, motor functional disability, and neuronal cell loss induced by global cerebral ischemia. These results suggest that HE may be a potential candidate for the treatment of vascular dementia.
        63.
        2010.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to analyze and compare the effect of resistance exercise and balance exercise on proprioception and WOMAC index of patients with degenerative knee osteoarthritis. A total of 40 subjects participated in this study. The subjects were diagnosed with degenerative knee osteoarthritis and all were more than 60 years old. They were divided into three groups. Group Ⅰ(n=8) was trained with resistance exercise, Group Ⅱ(n=6) was trained with balance exercise and GroupⅢ(n=6) was trained with range of motion as a control. The results of this study were as follows. It was significantly indicated that the resistance exercise group and balance exercise group elicited error-reduction on proprioception goal-angle (p<.05). There was a statistically significant difference on proprioception between resistance exercise group and control(range of motion) group. There was a statistically significant reduction on WOMAC index between resistance exercise group and balance exercise group (p<.05) and on the WOMAC index between resistance exercise group and range of motion group(p<.05). In conclusion, resistance exercise and balance exercise are effective on degenerative knee osteoarthritis and resistance exercise is the most effective for improving proprioception and WOMAC index. More research on the intervention according to the degree of degenerative knee osteoarthritis is needed.
        4,000원
        64.
        2009.03 구독 인증기관 무료, 개인회원 유료
        In our present study, total methanol extracts prepared from B. platyphylla var. japonica showed a significant increase in cell proliferation upon the induction of oxidative stress by hydrogen peroxide or y-ray irradiation. Total methanol extracts were fractionated into five separate preparations i.e. n-hexane, dichloromethane, ethylacetate, n-butanol and water fractions. Among these, the ethylacetate and butanol fractions of B. platyphylla var. japonica showed the highest protective effects against oxidative stress induced by hydrogen peroxide. These fractions also showed strong protective effects against y-ray irradiation. When we evaluated the cytotoxicity of these fractions, the butanol fraction showed no effects in a colony formation assay. In addition, the butanol fraction showed a cell proliferation activation effect evidenced by significant increase in the colony formation of y-ray irradiated cells. Both a radical scavenging activity and clonogenic activity assay suggested that the mechanism behind this protective effect against reactive oxygen species may be due to the radical scavenging and cell proliferation activity of B. platyphylla var. japonica extracts.
        4,000원
        66.
        2008.05 구독 인증기관·개인회원 무료
        Temperature-dependent development and oviposition component models were developed for Pseudococcus cryptus Hempel (Homoptera: Pseudococcidae). Egg development times decreased with increasing temperature and ranged from 2.4d at 16℃ to 1.0d at 28℃. Total development times of nymphs reared on citrus leaves decreased from 54.9d at 16℃ to 17.4d at 28℃ and 19.3d at 32℃. As P. cryptus showed an ovoviviparous reproductive behavior, the periods of egg and the 1st nymph were combined. By fitting linear models to the data the lower developmental threshold temperatures for egg-1st nymphs, the 2nd nymphs, the 3rd nymphs, and all nymphs combined were calculated as 8.7, 12.8, 13.1, and 12.1℃, respectively. The thermal constants were 198.6, 84.7, 69.8, and 296.3 degree-days for each of the above stages. The non-linear model based on a Gaussian equation, which fits the relationship between development rate and temperature was well for all stages. Adult longevity decreased with increasing temperature and ranged from 80.4d at 16 to 31.3d at 32.0℃. Also, preoviposition and oviposition periods showed a similar pattern with the longevity. P. cryptus had a maximum fecundity of 111 eggs per female at 28℃, which declined to 102.7 eggs per female at 32℃.
        67.
        2008.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        이 연구에서는 플라즈마 제염 기술의 실용화를 위해 , , 등의 반응성 플라즈마 기체를 이용하여 원자력 시설의 주요 오염원인 코발트 핵종에 대한 표면 제염 모의실험을 수행하였다. 디스크 형태의 금속코발트에 대하여 시편 표면 온도를 변수로 플라즈마 식각 실험을 수행한 결과 반응율은 에서 기체의 경우 그리고 와 기체의 경우 각각 과 이었으며, 이들 반응의 활성화에너지는 각각 39.4 kJ/mol, 42.1 kJ/mol, 116.0 kJ/mol이었다. 이와 함께 AES (Auger Electron Spectroscopy)를 이용하여 반응 생성물 성분 분석 결과 이들 반응의 주요 반응 기구는 코발트의 불화 반응임이 밝혀졌다. 이 연구를 통해 확보된 의 금속 표면 식각율은 주요 반도체 공정의 식각율을 뛰어넘는 높은 식각율로 플라즈마 제 염 기술의 실용화를 앞당길 수 있는 고무적인 결과라 할 수 있을 것이다.
        4,000원
        68.
        2007.04 KCI 등재 구독 인증기관·개인회원 무료
        Sulfur is commonly used in Asia as an herbal medicine to treat inflammation and cancer , a nd potent chemo preventi ve effects have been demons tra ted in various in vivo and in vitromodels for s ul fur-containing compounds found in natura l1y occurring product s. Here, we 1'eport the growth inhibitory and apoptosis-related effects of a n ewly developedhigh-puri ty edible sulfur(ES) on immo1'tali zed human o1'al ke1'atinocytes(IHOKs) and on oral cancer cells representing two stages of oral cancer (HN4‘ HN12) based on an 3-(4,5-Dimethylthiazol-2-yl) -2.5- diphe n yltetrazolium bromide(MTI) assay, Western blotting, cell cycle analysis, and nuclear staining. The puri ty of the ES used in thi s study was ve1'ified by high performance liquid chromatog1'aphy (HPLC) , ami no acid analysis and energy dispersive spectroscopy(EDS). ES inhibited the prolife1'ation of imrnortalized and ma lig nant o1'al kerati nocytes in a dose- and time-dependent manne1' FITC-Annex.in V staining, DNA fragmentation t esting. and Hoechst 33258 s taining revealed that ES inhibits cell growth via apoptosis. ES bl ocked cell-cycle prog1'ession at t he sub-Gl phase‘ wi th decreased expression of cyclins Dl, D2‘ and E, and their activating partn ers cdk2‘ cdk4‘ and cdkfì, and a concomitant induction of p53 and p21/WAF1. Furthe1'more, ES treatment in creased the cytosolic level of cytochrome c and resulted in caspase- 3 activation‘ and thi s effect was co1'1'elated with Bax up-regulation and Bcl-2 down-1'egulation Taken together‘ these data suggest that ES is a potential chemopreventive and chemotherapeut ic agent fo r oral ca ncer
        69.
        2007.04 KCI 등재 구독 인증기관·개인회원 무료
        Al though the changes in tooth morphology and hardness by hydrogen peroxide(H20 z) have been r‘epor‘.ted .‘ the pαr。o야t뻐ec야tive role of heme oxygenase-l(HO-l) against the cytotoxic effects of H202 has not been clarifïed i n human pulp cells ln this st udy. we investigated whether HO-l is involved in Hz0 2-induced cytoLox icity a nd examined the production 0 1' dentin sia lophosphoprotein(DSPP) and other mineralization markers‘ in hllman pu lp cells H202 decreased cell viabi lity, but increased HO-l and DSPP expression in a concentra tion and time dependent manner . Inhibitors of gllanylate cyclase. PI3K, ERK. and p38 MAP kinase blocked H202-indllced cytotoxicity and the expression of HO-l and DSPP mRNAs in pulp cells. These data suggest that the induction of HO-l by H202 in plllp cells plays a protective role against the cytotoxic effects 0 1' HzOz and stimulates DSPP expression‘ reslllting in prematllre odontoblast dilTerentiation throllgh pathways that involve cGMP‘ p38. and ERK.
        70.
        2007.04 KCI 등재 구독 인증기관·개인회원 무료
        Al t hough substance P(SP) , a potent pro- inflammatory peptide, is involved in inflammation and immune responses‘ t he eff'ect of SP on t he expression of macrophage inflammatory protein 3a (MIP- 3α CCL20) in periodontal liga ment(PDL) cell s a re unknown, Equally as enigmatic is the link between SP, t he stress protein heme oxygenase- l(HO-l) ‘ and CCL20 procluction, We investigated whether SP induces the release of chemokine CCL20 from immortal ized PDL(IPDL) ceJJ s‘ and fur ther c l a꺼 SP mediated pathways, We also examined the relationship between HO-l a ncl CCL20 by t reating PDL cells with SP, Incubating IPDL cells with SP increased expression of CCL20 mRNA a nd CCL20 protein in a dose-time dependent manner Highly selective p38 and ERKl/2 inhibitors abrogated SP-induced expression of CCL20 in IPDL cell s, SP is a lso responsible for ini t iating phosphorylation of I/C B, degradation of Iκ B‘ ancl activat ion of NF'-/C B, SP induced expression of HO-l in both a concentration- and time-dependent man nel ‘ and CCL20 refl ected s imilar patterns, The inductive effects o[ SP on HO- l and CCL20 wer e enhanced by HO- j inducer hemin and the membrane-permeable cGMP analog 8-bromo-cGMP, Conversely, this pathway was inJübited by t he 1-10난 inhi bitor zinc protoporphyrin IX(ZnPP IX) and the selective inl뼈itor of guanylate cyc1ase‘ lH-[l , 2, 4Joxad iazole[4‘ 3-aJquinoxal in-l-one (ODQ) , We report herein the pathway that connects SP along with other modulators 。f neuroimmunoregulationto the induction of HO-l and t he inflammatory mediator MIP-3a /CCL20 in IPDL cell s‘ which play an important role in the development 01' periodontitis or inflamrnation during orthodontic tooth movem
        73.
        2005.10 KCI 등재 구독 인증기관·개인회원 무료
        This study was to taken to demonstrate the effects of exogenous nitric oxide(NO) on hu rnan pu lp cell s ‘ In volvement of cyclic 3’, 5' -monophosphate(cGMP) in p버 paJ protection induced by herne oxygenase-l (J-lO-l) against NO-induced cytotoxicity , By use of Western blotting and cell viabi lity assay, we have examined the cytotoxicity and J-lO-l induction in pulp cells that were treated with NO donor ‘ S-nitroso-N-acetyl-D, L-penici 1 lamine(SNAP) , We have assessed wheathel' HQ--l contributes the cytoprotective effect against the cytotoxicity caused by NO, and inves tigated the l'elationship between HO-l and cGMP in the s ignaling pathway, SNAP decreased cell via bility but in creased HO-l expl'ession in a concentl'ation- and time一dependent manner in hurnan pu lp cells NO-induced cyto toxicity was inhibited in the presence of the hemin(inducer of HO-l) , whel'eas was en hanced in the pl'esence zinc protoporphyrin IX(ZnPP IX, HO-l inhibitor), thus Lhe NO-induced cytoLoxicity was cOl'related with HO- l expression. R‘ etreatment with a rnemhrane-permeable cGMP analog, 8-bromo-cGMP, restored cell death and enhanced the HO-l protein expression induced by SNAP, ln contrast‘ inhibition of guanylate cyclase by lI-l -[1,2,4] ox adiazole[ 4,3 口]quinoxalin-l-one(ODQ) pretreated pulp cells to 1 mM SNAP resulting in marked cytotoxicity , These findings , demonstrating a link between J-lO-l, regulated thl'ough the cGMP system and NO-induced cytotox.icity in huma띠 p버 p ceJls , suggesti ng a protective 1'ole of HO-l in pulp infl ammatory disease
        76.
        2004.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 콘크리트 교량의 지진취약도 곡선을 개발함에 있어 성능 스펙트럼 기법(Capacity Spectrum Method)에 대한 고찰을 통해 가장 적절한 해석방법을 제시하는데 그 목적이 있다. 원래 성능 스펙트럼 기법은 빌딩 구조물을 위한 간략화된 정적 비선형 해석의 일환으로 개발되었는 바, 본 연구에서는 이 기법을 교량의 지진취약도 곡선을 개발하는데 응용하였다. 서로 다른 네가지의 방법으로 성능 스펙트럼 기법을 통해 구해진 취약도 곡선들을 비선형 시간이력해석 방법에 의해 구해진 취약도 곡선과 비교하였다. 취약도 곡선은 두 개의 변수를 가진 lognormal 분포를 따르는 것으로 가정하였으며 PGA(Peak Ground Acceleration)의 함수로 나타내어졌다. FEMA(Federal Emergency Management Agency) SAC(SEAOC-ATC-CUREe) steel 프로젝트에 의해 개발된 로스앤젤레스 지역 60개의 지진이 교량해석을 위해 사용되었다. 성능 스펙트럼 기법과 시간이력해석에 따라 만들어진 교량의 지진취약도 곡선들을 비교 검토한 바, 이 중 하나의 방법이 부합되는 결과를 보여주었다. 요구 스펙트럼 작성시 본 논문에서 제시된 지침을 따르면 비선형 시간이력 해석시와 유사한 결과를 얻을 수 있을 것으로 사료된다. 다만 지진과 교량이 지닌 특수성으로 인해 본 연구의 결과가 항상 적용되는지는 더 심도있는 연구를 통해 검증되어야 할 것이다.
        4,000원
        77.
        2003.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        다수의 지점 위에 놓인 교량의 경우, 지진으로 인한 지반운동은 교량길이에 따른 거리에 걸쳐 지점마다 현저하게 다를 수 있다. 본 연구는 이러한 공간적 특성을 고려하기 위하여 지점마다 다른 진폭과 위상 그리고 주파수 성분을 갖도록 지반운동 시간이력곡선을 생성하였고, Monte Carlo 해석기법을 사용하여 생성된 지반운동 하에서 교량의 비선형 동적거동을 고찰하였으며 두개의 실제 교량에 대한 취약도 해석을 수행하였다. 공간적 특성이 지진반응에 미치는 영향을 고려하여 교량교각의 연성도에 대한 취약도 곡선을 개발하였고, 동일지진 하에서의 취약도 곡선과 비교 검토하였다. 본 연구는 동일 지반운동을 사용하여 교량해석을 수행하는 경우 교각의 요구 연성계수가 상이 지반운동을 사용하는 경우보다 저평가 될 수 있다는 것을 입증하였다. 지진취약도 곡선은 지반운동의 강도를 표시하는 PGA, PGV, SA, SV와 SI의 함수로 나타내어졌다. 본 연구는 최초로 공간적 특성을 반영한 지반운동 하에서의 지진취약도 곡선을 개발하였으며, 다경간 교량의 내진설계시 시방서에 그 영향을 고려하기 위한 설계지침의 근거를 제공할 것이다.
        4,500원
        78.
        2001.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We have studied the nonlinear evolution of a magnetized disk of isothermal gas, which is sustained by its self-gravity. Our objective is to investigate how the Jeans, Parker, and convective instabilities compete with each other in structuring/de-structuring large scale condensations in such disk. The Poisson equation for the self-gravity has been solved with a fourth-order accurate Fourier method along with the Green function, and the MHD part has been handled by an isothermal TVD code. When large wavelength perturbations are applied, the combined action of the Jeans and Parker instabilities suppresses the development of the convection and forms a dense core of prolate shape in the mid-plane. Peripheral structures around it are filamentary. The low density filaments connect the dense core to the diffuse upper region. On the other hand, when small wavelength perturbations are applied, the disk develops into an equilibrium state which is reminiscent of the Mouschovias's 2-D non-linear equilibrium of the classical Parker instability under an externally given gravity.
        3,000원
        80.
        1999.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have constructed a synthetic spectrum of the 2.5 micron C2H C2H bands and compared them with diminutive structures in the near-infrared spectra of Comets P/Halley and West (1976 VI). We found that the Q branches of the C2H C2H bands coincide with two small emission peaks in the spectra of the comets. We undertook Monte Carlo simulations using observed emission intensities of C2 C2 and possibly C2H C2H in Comet P/Halley in order to derive a lifetime range of C2H C2H and a production rate at the time of observations of P/Halley. We obtained a C2H C2H production rate of 1×1027sec−1 1×1027sec−1 for P/Halley on December 20, 1985, assuming the 2.5 micron features are due to C2H C2H . We derived a very short lifetime (<100 seconds) of C2H C2H at 1AU heliocentric distance, assuming that the only parent molecule for C2H C2H and C2 C2 is C2H C2H . Using this short lifetime we were unable to fit our C2 C2 distribution model to C2 C2 distribution curves observed by O'Dell et al.(1988), because our curve shows a steep slope compared with the observed one. We conclude that there must be significant additional source(s) for C2H C2H and C2 C2 other than C2H2 C2H2 .
        4,000원
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