Antiangiogenic activity of low-temperature lysozyme from a marine bacterium <Emphasis Type="Italic">in vivo</Emphasis> and <Emphasis Type="Italic">in vitro</Emphasis>     

王振华  刘金成  苏爱  孙谧  王春波 《中国海洋湖沼学报》2009,27(4):835-844

We extracted marine low-temperature lysozyme (MLTL), a novel lysozyme, from a marine microorganism through fermentation. Our previous study suggested that a low molecular weight (16 kDa) may exert anti-tumor activity through antiangiogenesis. In this study, we extracted a high weight (39 kDa) and investigated its antiangiogenic activity in vivo and in vitro. Using zebrafish embryos as an in vivo study model, we found that treatment with MLTL significantly inhibited the growth of subintestinal vessels (SIVs) in a dose-dependent manner and that 400 μg/ml MLTL was sufficient to block the growth of SIVs. An in vitro study conducted using human umbilical vein endothelial cells (HUVECs) revealed that MLTL suppressed the proliferation, migration and tube formation of HUVECs in a dose-dependent manner. Interestingly, assays by flow cytometry and DNA electrophoresis indicated that MLTL was able to induce apoptosis of HUVECs. Moreover, further study demonstrated that the disruption of intracellular Ca²⁺ homeostasis may play an important role in MLTL induced apoptosis of HUVECs. Taken together, the results of this study demonstrate for the first time that MLTL inhibits angiogenesis through its pleiotropic effects on vascular endothelial cells and induces apoptosis through regulation of cellular Ca²⁺ levels. The results of this study also revealed a possible mechanism underlying the antiangiogenic effect of MLTL and suggested that MLTL may be a promising new antiangiogenic agent for use in cancer therapy.  相似文献   

基于非线性动力学模型的旅游生态容量分析   总被引：1，自引：0，他引：1  

吕龙  黄震方  吴江 《地球信息科学学报》2009,11(2):163-168

近年来,大量增加的游客给景区的旅游生态容量带来了较大的压力,矛盾日渐突出。为了实现景区的环境保护与可持续发展,研究游客活动量与景区旅游生态容量之间的关系是十分必要的。本文从非线性动力学观点出发,构建二者非线性动力学模型,并进行平衡态分析。研究结果表明:(1)系统要达到可持续发展,必须建立在景区环境的自我更新能力及人工恢复程度之和大于外界污染水平,且游客的增长率必须保持在较低水平的基础上;(2)景区旅游生态容量的承载力是有限的,所能容纳的游客也是有限的,超过一定的限度就会引起生态系统失衡。采取严格控制游客量,加强对景区内外环境的保护和改善、提升游客素养等措施,对于系统的协调发展至关重要。  相似文献   

美国人权措施对中美贸易的消极影响及对策     

李良才 《广东海洋大学学报》2009,29(5):34-38

WTO多边贸易体制倡导自由贸易。WTO成员之间应当削减或取消一切贸易壁垒,共同承担多边自由贸易的义务。美国根据国内贸易法采取的人权措施具有单边性、任意性并且暴露了此类贸易限制或禁止措施的霸权主义本质。美国人权措施引发了诸多贸易争端,严重挑战自由贸易精神。美国对华实施人权措施造成我国对美出口遭遇不利影响。我国应从革新外贸立法理念、增设人权措施条款并适度运用人权措施等方面积极应对此类新型贸易壁垒。  相似文献   

The journal Communications in Numerical Methods in Engineering with Biomedical Applications becomes the International Journal for Numerical Methods in Biomedical Engineering (IJNMBE) from 1st January 2010     

Perumal Nithiarasu  Rainald Löhner 《国际地质力学数值与分析法杂志》2009,33(16):1769-1770

Communications in Numerical Methods in Engineering, founded by Roland W. Lewis in 1985, will change its title to the ‘International Journal for Numerical Methods in Biomedical Engineering’ and has a revised Aims and Scope. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

黄河三角洲北部贝壳堤岛的近期演变   总被引：2，自引：0，他引：2  

杜廷芹  黄海军  王珍岩  刘艳霞 《海洋地质与第四纪地质》2009,(3)

通过不同年代地形图、卫星影像的对比及野外实地测量等,综合分析了黄河三角洲北部开敞型和潮沟型两类贝壳堤岛近50年来的数量和面积变化及其演化特征。结果表明,该区两类贝壳堤岛自20世纪50年代以来在自然和人为因素的共同作用下发生了明显的变化,但其演化特征因岛屿成因的类型差异而各不相同。目前,该区贝壳堤岛群逐渐萎缩,人类活动已成为影响三角洲北部两类贝壳堤岛发育演变的主导因素,特别是潮沟型贝壳堤岛,基本上结束了自然演化的历史,呈现出新的演化特征。  相似文献   

Reconstruction of fire spread within wildland fire events in Northern Eurasia from the MODIS active fire product   总被引：1，自引：0，他引：1  

T.V. Loboda  I.A. Csiszar   《Global and Planetary Change》2007,56(3-4):258

Russian boreal forests have been reshaped by wildland fire for millennia. While fire is a natural component of boreal ecosystems, it impacts various aspects of the environment and affects human well-being. Often fires occur over large remote areas with limited access, which makes their ground-based observation difficult. A significant progress has been made in mapping burned area from satellite imagery, which provides consistent and fairly unbiased estimates of fire impact on areas of interest at multiple scales. Although the information provided by burned area products is highly important, the spatio-temporal dynamics of individual fire events and their impact are less known. In high northern latitudes of Northern Eurasia, MODIS (Moderate Resolution Imaging Spectroradiometer) makes up to four daily observations from each of the Terra and Aqua satellites providing consistent data on fire development with high temporal frequency. Here we introduce an approach to reconstruct the development of fire events based on active fire detections from MODIS. Fire Spread Reconstruction (FSR) provides a means for characterization of fire occurrence over large territories from remotely sensed data. Individual fire detections are clustered within a GIS environment based on a set of rules determining proximity between fire observations in space and time. FSR determines the number of fire events, their approximate size, duration, and fire spread rate and allows for the analysis of fire occurrence and spread as a function of vegetation, fire season, fire weather and other parameters. FSR clusters were compared to burned scars mapped from Landsat7/ETM+ imagery over Yakutia (Russia). While some smaller burn scars were found to be formed through a continuous burning of a single fire event, large burned areas in Siberia were created by a constellation of fire events incorporating over 100 individual fire clusters. Geographic regions were found to have a stronger influence on the rates of fire activity in the area compared to vegetation zones. In addition, fire spread rates do not directly correlate with the intensity of a given fire season. FSR is also used to identify the points of ignition for individual fire events in spatio-temporal domain for fire danger and fire threat modeling. This approach presents another step towards the more complete characterization of fire events from remotely sensed data.  相似文献   

Impact of Human Activities on Depositional Process of Tidal Flat in Quanzhou Bay of China   总被引：2，自引：0，他引：2  

WANG Aijun 《中国地理科学(英文版)》2007,17(3):265-269

As a very important component of a coastal system,tidal flats come to be a focus of the studies on land-ocean interaction in the coastal zone because those areas are subjected to intense human activities and are highly sensitive to the global change.The Quanzhou Bay,located along the middle part of Fujian coast of China,covers about 136.4km2,and the area of coastal wetland in the entire bay from intertidal to subtidal with 6m of water depth accounts for 96% of the total area.Seven short cores were collected and divided in situ with the interval of 5cm on the coastal wetlands of Quanzhou Bay on April 19,2006.The sediment samples were scattered and the grain sizes were measured by using Mastersizer 2000.Human beings' activities on tidal flat have disturbed the vertical distribution of sediments in stratigraphic sequence and accelerated the sedimentation rates.Grain size analysis results show that the grain size diameters increase and sediment becomes worse sorted towards the sea under the strong human disturbance;Spartina alterniflora can play a role of trapping the fine sediment;but near the bank,the sediment becomes coarse and there are two peak values on frequency curve influenced by the sandpile.The trough formed by human activities along the coastline changes the transport path of water and suspended sediment.The sediments are transported through the trough and deposit in it during the flood;the ebb flow is retarded by the flow output through the adjacent trough,and the deposited sediment can not be re-suspended;then,the sedimentation rate increases.In situ observation show that the sedimentation rate is about 8-10cm/yr.  相似文献   

基于整合理论的高校教师管理     

高海军  徐蕾  王卓 《成都信息工程学院学报》2007,22(2):294-296

整合理论实质就是对组织所拥有的资源进行优化配置,使其协调发展,产生最大效益.对于高校,教师是所拥有的不可缺少,最具有潜力的资源,这种资源所发挥的协同作用存在巨大的潜力.从整合理论的角度,分析了高校教师管理方面的整合问题,提出了高校教师管理过程中应该注意的问题.  相似文献   

辽宁省城市人居环境系统耦合协调度时空格局演变及驱动力研究   总被引：2，自引：0，他引：2  

李雪铭  郭玉洁  田深圳  白芝珍  刘贺 《地理科学》2019,39(8):1208-1218

人居环境系统内部的耦合协调是保证人居环境均衡发展的基础。基于“人类-居住-支撑-自然-社会”5个子系统,构建人居环境系统耦合协调发展评价指标体系,将2个系统间的容量耦合模型扩展运用到人居环境5个子系统中,综合熵值法、GIS空间分析以及地理探测器对辽宁省2005~2016年人居环境系统耦合协调度的时空演化特征与驱动力进行探讨,阐述人居环境系统内部协调性。研究表明:①2005~2016年辽宁省人居环境系统内部的耦合度与耦合协调度整体呈缓慢浮动上升趋势;②辽宁省人居环境耦合协调度呈分散格局,并且呈现从中间向两侧递减的“屋脊”式格局和“双核结构”;东西方向上,空间演变趋势由倒U型逐渐向一字型演变,南北方向上由斜线型向“L”型演变。③全省出现了中耦合低协调区、中耦合过渡协调区、高耦合低协调区、高耦合过渡协调区、高耦合高协调区5种类型区。④空间分异驱动力主要包括人的需求、经济发展、住房、互联网发展等。  相似文献   

气候和人为因素对植被变化影响的评价方法综述   总被引：1，自引：1，他引：1  

马启民  贾晓鹏  王海兵  李永山  李劭宁 《中国沙漠》2019,39(6):48-55

系统评价气候变化和人为因素引起的植被退化，对有效开展生态工程建设、实现生态环境的可持续发展具有重要意义。目前绝大多研究主要分析气候因素对植被变化的影响，分析气候因素和人类活动对植被变化的双重影响少有研究。本文主要介绍这一双重影响对植被变化的贡献程度的主要研究方法——定性-半定量法、回归分析法、残差趋势法、基于净第一生产力的评价方法。综述分析了气候和人为因素对植被变化驱动的主要结论，总结目前各研究方法存在的问题，提出了未来需要重点加强气候和人为因素对植被变化驱动因素的分解研究，加强模型评价和不确定性量化研究等。  相似文献