• 제목/요약/키워드: Aggregation Function

검색결과 210건 처리시간 0.026초

인삼이 신 질환 환자에서 신 기능에 미치는 영향 (Effect of Ginseng on Renal Function in Patient with Renal Injury)

  • 김형규;조원용;구자룡
    • Journal of Ginseng Research
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    • 제21권1호
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    • pp.49-52
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    • 1997
  • There are many mechanisms that mediate progression of renal injury, such as abnormalities of nitric oxide (NO) regulation, increased Platelet aggregatlon, and oxygen free radical injury. Ginseng has been known to have NO dependent vasorelaxant effect and antioxidant effect, also inhibit thrombin stimulated platelet aggregation. And these effects of ginseng may have some roles in prevention of renal injury. So we studied 24 patients with mild pathologic proteinuria and hypertension to evaluate the effect of ginseng on progression of renal injury. After 1 month treatment, creatinine clearance was significantly increased especially in the patient group with normal serum creatinine level without specific side effect. The result of this study suggest that ginseng may pre vent or retard the progression of renal injury especially in early stage.

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비선형계통 고장진단을 위한 온-라인 퍼지동적모델 식별 (Identification of Fuzzy Dynamic Model for Fault Diagnosis of Nonlinear System)

  • 이종렬;배상욱;이기상;박귀태
    • 한국지능시스템학회:학술대회논문집
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    • 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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    • pp.204-210
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    • 1998
  • This paper discusses an on-line fuzzy dynamic model(FDM) identification of nonlinear processes for the design of fuzzy model based fault detection and isolation(FDI). The dynamic behavior of a nonlinear process is represented by a fuzzy aggregation of a set of local linear models. The identification is divided into two procedures. The first is the off-line identification of membership function. The second is the on-line identification of the local linear models. Then, we propose a residual generation scheme based on the parameters of local linear models and show that the scheme can be used for the design of FDI

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개심술시 체외순환이 혈소판에 미치는 영향 (Effect of Cardiopulmonary Bypass on Platelet)

  • 최대융
    • Journal of Chest Surgery
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    • 제25권5호
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    • pp.526-532
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    • 1992
  • The effect of cardiopulmonary bypass on platelet count and function was studied in 20 patients who underwent cardiac operation from April 1991 to August 1991 at the Department of thoracic and Cardiovascular Surgery, School of Medicine, Keimyung University. Ten patients were perfused with a bubble oxygenator, 10 with a membrane oxygenator. During and after bypass, platelet counts decreased in both groups and significantly reduced in those perfused with a bubble oxygenator. All 20 patients studied for platelet functions had an abnormal postoperative aggregation response to collagen and epinephrine, but no significant difference in both groups. One hour after bypass, bleeding times increased in both groups but did not differ significantly between groups. Postoperative 24 hour blood losses were significantly higher in patients perfused with a membrane oxygenator. Platelet damage and postoperative blood loss are less severe after cardiopulmonary bypass performed with a membrane oxygenator than with a bubble oxygenator.

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Size Dependent Absorption Spectrum of ZnO Nanocrystals

  • Chang Ho Jung;Wang Yongsheng;Suh Kwang-Jong;Son Chang-Sik
    • 한국재료학회지
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    • 제15권7호
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    • pp.431-434
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    • 2005
  • To investigate the dependences of the absorption spectrum and electronic structure properties on the ZnO nano-particle size, ZnO nanocrystals were synthesized by a sol-gel method. The absorption onset peak exhibits a systematic blue-shift with decreasing particle size due to the quantum confinement effect, as well as, with decreasing $Zn^{2+}$ concentration. The increase of particle size is mainly controlled by coarsening and aggregation step during the nucleation and growth of ZnO nano-particles. The onset absorption spectrum of ZnO colloids changes from 310 to 355 nm as $Zn^{2+}$ concentration increases from 0.01 to 0.1 mole. The average particle size as a function of aging- time can be determined from the absorption spectra. The freshly prepared nanocrystal size was about 2.8nm.

COX-2 억제제의 구조-활성 (SAR of COX-2 Inhibitors)

  • 권순경
    • Biomolecules & Therapeutics
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    • 제9권2호
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    • pp.69-78
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    • 2001
  • Cyclooxygenase (COX) is an enzyme, which catalyzes the production of prostaglandins from arachi-donic acid and exists in two isoforms (COX-1 and COX-2). COX-1 is involved in the maintenance of physiological functions such as platelet aggregation, cytoprotection in the stomach and maintenance of normal kidney function. COX-2 is induced significantly in vivo under inflammatory conditions. COX-1 and COX-2 serve different physiological and pathological functions. All commercially available nonsteroidal antiinflammatory drugs (NSAIDS) are inhibitors of both COX-1 and COX-2. Therefore, selective inhibitors of COX-2 may be effective antiinflammatory agents without the ulcerogenic effects associated with current NSAms. Since the mid 1990s, a number of reports have been appeared on the preparation and biological activity of selective COX-2 inhibitors. Recently celecoxib, and rofecoxib, the representative COX-2 inhibitors, are introduced in the drug market. In this paper the relationship of structure-activity for selective COX-2 inhibitors is reviewed.

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Hydrophilic Albumin Microspheres as Cytarabine Carriers

  • Kim, Chong-Kook;Chung, Myung-Hoa;Oh, Yu-Kyoung;Lah, Woon-Lyong
    • Archives of Pharmacal Research
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    • 제16권2호
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    • pp.123-128
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    • 1993
  • The surface of cyarabine-entrapped albumin microspheres, the surface modified albumin microspheres hsowed remakably incrased hydrophilicity, good dispersability in aqueous medium and reduced aggregation during storage which met the requirements of injectable drug carriers in acqueous vehicle. In vitro cytarabine release from hydrophilic albumin microspheres (HAM) was a function of the cytarabine to albumin ratio, whereas no significant difference in the releasing capacity was obnserved between surface modified HAM within the small size range$(2\;to\;5\mu{m)}$ studied. HAM containing 15-23% drug were gradually degraded by protease and continuously released up to 60% of the total entrapped cytarabine for 6h. These results thus suggest that HAM is a suitable cytarabine carrier which may be injected intraveneously with the benefits of a reduced risk of blood embolism induced by aggregates and prolonged cytarabine release.

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Euchrestaflavanone A can attenuate thrombosis through inhibition of collagen-induced platelet activation

  • Shin, Jung-Hae;Kwon, Hyuk-Woo
    • Journal of Applied Biological Chemistry
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    • 제63권4호
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    • pp.339-345
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    • 2020
  • Euchrestaflavanone A (EFA) is a flavonoid found in the root bark of Cudrania tricuspidata. C. tricuspidata extract, widely used throughout Asia in traditional medicine, has been investigated phytochemically and biologically and is known to have anti-obesity, anti-inflammatory, and anti-tumor effects. It has been reported that C. tricuspidata extract also possesses anti-platelet effects; however, the mechanism of its anti-platelet and anti-thrombotic activities is yet to be elucidated. In this study, we investigated the effects of EFA on the modulation of platelet function using collagen-induced human platelets. Our results showed that EFA markedly inhibited platelet aggregation. Furthermore, it downregulated glycoprotein IIb/IIIa (αIIb/β3)-mediated signaling events, including platelet adhesion, granule secretion, thromboxane A2 production, and clot retraction, but upregulated the cyclic adenosine monophosphate-dependent pathway. Taken together, EFA possesses strong anti-platelet and anti-thrombotic properties and is a potential therapeutic drug candidate to prevent platelet-related thrombosis and cardiovascular disease.

Inhibitory Effects of Manassantin A and B Isolated from the Roots of Saururus chinensis on PMA-Induced ICAM-l Expression

  • Eok, Kwon-Oh;Lee, Seung-Woong;Chung, Mi-Yeon;Kim, Young-Ho;Kim, Koan-Hoi;Rho, Mun-Chual;Lee, Hyun-Sun;Kim, Young-Kook
    • 대한약학회:학술대회논문집
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    • 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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    • pp.199.1-199.1
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    • 2003
  • In the course of our search for intercellular adhesion molecule-1 (ICAM-1)/leukocyte function-associated antigen-1 (LFA-1) mediated cell adhesion inhibitors from natural sources, new type of cell adhesion inhibitors were isolated from the MeOH extract of Saururus chinensis roots. On the basis of spectral evidence, the structures of the active compounds were identified as manassantin A and B. Manassantin A and B inhibited phorbol 12-myristate 13-acetate (PMA)-induced homotypic aggregation of the human promyelocytic leukemia HL-60 cells without cytotoxicity with MIC value of 1.0 and 5.5 nM, respectively. (omitted)

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Application of Scaling Theories to Estimate Particle Aggregation in a Colloidal Suspension

  • Park, Soongwan;Koo, Sangkyun
    • Korean Chemical Engineering Research
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    • 제60권2호
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    • pp.260-266
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    • 2022
  • Average aggregate size in particulate suspensions is estimated with scaling theories based on fractal concept and elasticity of colloidal gel. The scaling theories are used to determine structure parameters of the aggregates, i.e., fractal dimension and power-law exponent for aggregate size reduction with shear stress using scaling behavior of elastic modulus and shear yield stress as a function of particle concentration. The structure parameters are utilized to predict aggregate size which varies with shear stress through rheological modeling. Experimentally rheological measurement is conducted for aqueous suspension of zinc oxide particles with average diameter of 110 nm. The predicted aggregate size is about 1135 nm at 1 s-1 and 739 nm at 1000 s-1 on the average over the particle concentrations. It has been found that the predicted aggregate size near 0.1 s-1 agrees with that the measured one by a dynamic light scattering analyzer operated un-sheared.

양식넙치 멜라닌 농축 호르몬의 특성 (Characterization of Melanin-concentrating Hormone from Olive Flounder (Paralichthys olivaceus))

  • 정인영;전정민;송영환
    • 생명과학회지
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    • 제28권3호
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    • pp.284-292
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    • 2018
  • 멜라닌 농축 호르몬(melanin-concentrating hormone, MCH)은 17개의 아미노산으로 구성된 환형의 시상하부 펩티드로 색소 침착의 조절인자로서 연어에서 처음 분리되었다. 포유동물의 MCH는 19개의 아미노산으로 구성되어 있으며 섭식 및 에너지 항상성을 조절하는데 관여한다. 본 연구에서는 양식넙치의 다양한 조직에서 MCH 유전자의 발현 분포, 멜라닌 함유 세포의 집적, 포유동물 MCH 수용체와 양식넙치 MCH의 상호작용을 조사하였다. Real-time qPCR을 이용하여 뇌, 정소, 난소에서 MCH 유전자의 발현이 나타나는 것을 확인하였고, 수정 후 발달 단계에서도 MCH 유전자의 발현을 확인할 수 있었다. 합성된 연어 sMCH, 포유류 hMCH, 양식넙치 fMCH, dN-fMCH, dC-fMCH를 양식 넙치의 표피에 처리했을 때 다양한 농도에 따라 멜라닌 함유 세포의 집적이 다양하게 나타났다. 연어 sMCH, 포유류 hMCH에 비해 양식넙치 fMCH의 멜라닌 함유세포의 집적도가 36~99.85%로 비역가를 나타났으나 양식넙치 dN-fMCH, dC-fMCH를 처리한 경우 양식넙치 fMCH에 비해 높은 농도에서 집적이 나타나고 짧은 시간에 분산되었다. 또한, 인간 MCH 수용체와 쥐 MCH 수용체가 발현된 포유동물의 세포주에 양식넙치 fMCH를 처리하여 각 수용체와 결합하는 것을 확인하였다. 이러한 결과는 어류에서 발현되는 MCH가 포유동물의 MCH와 유사한 구조를 가지고 있어 MCH 수용체에 대한 새로운 리간드로서 제공될 수 있으며, 향후 어류의 MCH 수용체에 확대 적용할 수 있을 것이다.