Ds-echinoside A, a new triterpene glycoside derived from sea cucumber, exhibits antimetastatic activity via the inhibition of NF-κB-dependent MMP-9 and VEGF expressions     

Zhao Q  Liu ZD  Xue Y  Wang JF  Li H  Tang QJ  Wang YM  Dong P  Xue CH 《Journal of Zhejiang University. Science. B》2011,12(7):534-544

Ds-echinoside A (DSEA), a non-sulfated triterpene glycoside, was isolated from the sea cucumber Pearsonothuria graeffei. In vitro and in vivo investigations were conducted on the effects of DSEA on tumor cell adhesion, migration, invasion, and angiogenesis. In this study, we found that DSEA inhibited the proliferation of human hepatocellular liver carcinoma cells Hep G2, with a half-maximal inhibitory concentration (IC₅₀) of 2.65 μmol/L, and suppressed Hep G2 cell adhesion, migration, and invasion in a dose-dependent manner. DSEA also reduced tube formation of human endothelial cells ECV-304 on matrigel in vitro and attenuated neovascularization in the chick embryo chorioallantoic membrane (CAM) assay in vivo. Immunocytochemical analysis revealed that DSEA significantly decreased the expression of matrix metalloproteinase-9 (MMP-9), which plays an important role in the degradation of basement membrane in tumor metastasis and angiogenesis. DSEA also increased the protein expression level of tissue inhibitor of metalloproteinase-1 (TIMP-1), an important regulator of MMP-9 activation. From the results of Western blotting, the expressions of nuclear factor-kappa B (NF-κB) and vascular endothelial growth factor (VEGF) were found to be remarkably reduced by DSEA. These findings suggest that DSEA exhibits a significant antimetastatic activity through the specific inhibition of NF-κB-dependent MMP-9 and VEGF expressions.  相似文献   

Effect of microcystin-LR on protein phosphatase 2A and its function in human amniotic epithelial cells     

Liang J  Li T  Zhang YL  Guo ZL  Xu LH 《Journal of Zhejiang University. Science. B》2011,12(12):951-960

Due to their toxicity, the increased distribution of microcystins (MCs) has become an important worldwide problem. MCs have been recognized as inhibitors of protein phosphatase 2A (PP2A) through their binding to the PP2A catalytic subunit. However, the exact mechanism of MC toxicity has not been elucidated, especially concerning the cellular response and its autoregulation. To further dissect the role of PP2A in MC-induced toxicity, the present study was undertaken to determine the response of PP2A in human amniotic epithelial (FL) cells treated with microcystin-LR (MCLR), one of the MC congeners. The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity, and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A, as expected. The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A. Furthermore, MCLR altered microtubule post-translational modifications through PP2A. These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.  相似文献   

Robots协议的法律效力探析--兼评百度诉360一案     

陈玮婧 《江苏广播电视大学学报》2015,(1)

自从奇虎360公司进军搜索引擎行业以来,其与百度公司之间的摩擦不断升级。百度在自己旗下的网站设置robots协议白名单,将360搜索引擎排除在外,而360则公然绕过robots协议,强行抓取百度网站页面。由于法律无明文规定,关于robots协议的法律效力值得探讨,但不管从哪个角度来分析,恶意越过ro-bots协议强行抓取网页或窥探隐私都应受到法律制裁,其具体是违反著作权法还是构成不正当竞争行为应视具体情况加以分析与选择。  相似文献   

教育财务管理信息系统设计     

吴泓 《科技广场》2014,(7):47-51

为提高学校的信息化管理水平,本文结合学校的业务需求和实际工作情况,研究并设计了适合学校的"教育财务管理信息系统",以期提高学校自身的财务管理效率,为学校的各项行政管理活动以及教学管理提供相关保障,从而促进学校更快更好地发展。本文基于软件工程面向对象的思想,采用统一建模语言UML进行财务管理系统的分析、设计和实现。  相似文献   

基于.NET的大学生创业信息服务平台建设与规划研究     

许丽娟 《科技广场》2014,(8):38-41

本文根据大学生创业园信息管理的需求,采用.NET技术,构建了一套基于B/S三层架构的综合信息服务管理平台。利用该平台,可以实现大学生创业管理信息化,为大学生创业提供更好的项目来源和技术支撑,提升大学生创业服务能力,整合各类创业资源,有效提高大学生创业的成功率。  相似文献   

Open access to data: An ideal professed but not practised     

Patrick Andreoli-Versbach  Frank Mueller-Langer 《Research Policy》2014

Data-sharing is an essential tool for replication, validation and extension of empirical results. Using a hand-collected data set describing the data-sharing behaviour of 488 randomly selected empirical researchers, we provide evidence that most researchers in economics and management do not share their data voluntarily. We derive testable hypotheses based on the theoretical literature on information-sharing and relate data-sharing to observable characteristics of researchers. We find empirical support for the hypotheses that voluntary data-sharing significantly increases with (a) academic tenure, (b) the quality of researchers, (c) the share of published articles subject to a mandatory data-disclosure policy of journals, and (d) personal attitudes towards “open science” principles. On the basis of our empirical evidence, we discuss a set of policy recommendations.  相似文献   

A dynamic auction for multi-object procurement under a hard budget constraint     

Ludwig Ensthaler  Thomas Giebe 《Research Policy》2014

This contribution revisits the problem of allocating R&D subsidies by government agencies. Typically, the applicants’ financial constraints are private information. The literature has recommended the use of auctions in order to reduce information rents and thus improve the efficiency of how scarce public funds are allocated. We propose a new open clock auction for this procurement problem. This auction is strategically simple, as it exhibits truthtelling in dominant strategies and satisfies ex-post rationality, while observing the budget constraint. We test the auction in Monte-Carlo simulation and discuss its applicability and limitations. Moreover, we highlight connections to recent advances in computer science.  相似文献   

第一性原理方法研究小芳香烃分子的基态性质     

王金华  李泽朋 《中国科技信息》2014,(9):59-62

采用基于密度泛函(DFT)和二阶多体微扰理论(MP2)的第一性原理方法对小芳香烃分子及其自由基的几何结构进行优化。计算结果表明,DFT中的B3LYP方法得到的最优化结构与实验结果符合得最好。相比大基底cc-pVTZ,小基底6-31G(d)得到的几何结构、能量与实验值符合得好。B3LYP方法计算得到氧原子在(d)位置的五苯环(C19H10O)体系最稳定。对小体系适用的理论方法(B3LYP)可以用来研究多环芳香烃(PAH)的性质。  相似文献   

基于B/S模式的综合信息系统集成平台的安全性措施   总被引：1，自引：0，他引：1  

鲍丽红  周荣辉 《天水师范学院学报》2004,24(2):40-43

管理信息系统发展到综合信息系统集成阶段后,安全问题成为系统集成工作中必须考虑的一个至关重要的问题。基于B/S模式的综合信息系统集成平台的安全性模型及该模型的具体实现方法、路线,在多用户的Web环境下,既能满足用户的需求又能最大限度地保证系统的安全,具有较强的实用性。  相似文献   

多媒体课件脚本规范运用   总被引：1，自引：0，他引：1  

方东傅 《湖州师范学院学报》2001,23(3):57-60

多媒体课件的脚本是根据课件总体设计方案 ,对各个目标进行的细化描述 .以A类脚本卡和B类脚本卡的形式正确、清晰地反映课件脚本如何围绕课件主题 ,对课件内容进行合理的分析 ,确定每个知识点的表现形式和表现手段 ,将知识单元按拟定的线索展开 .  相似文献