Vascular endothelial growth factor (VEGF) induces rapid prourokinase (pro-uPA) activation on the surface of endothelial cells

Vascular endothelial growth factor (VEGF) is the pivotal angiogenic growth factor activating endothelial cells to migrate, proliferate, and form capillary tubes. For an ordered endothelial cell migration, tissue invasion, and degradation of the extracellular matrix, proteolytic machinery is indispensable. Such machinery, suitable for localized proteolysis, is provided by the prourokinase-urokinase-plasmin system. Prourokinase (pro-uPA), the initial component of this system, is, however, synthesized in its inactive precursor form and as such bound to its cellular receptor uPAR. Here we identify a mechanism via which VEGF(165) interacting with its receptor VEGFR-2 rapidly induces prourokinase activation that is dependent on a change in integrin affinity, activation of matrix metalloproteinase 2 (MMP-2), and pro-uPA being bound to its surface receptor uPAR. This VEGF-induced pro-uPA activation on endothelial cells is responsible for VEGF-dependent local fibrinolytic activity and might be one of the initial steps in the angiogenic process.     

EPON--掀开光纤接入新的篇章

无源光网络的目的是通过建立一套成本低廉，且其带宽容量又是其他接入技术无法企及的端到端的解决方案，从而打破带宽的瓶颈。基于以太网的无源光网络EPON是一个点到多点的光接入网，采用低成本，高性能的以太网芯片为终端用户提供可靠的数据，话音以及视频业务，其所能提供的带宽远大于现有接入技术。本文主要介绍EPON技术的演化和分类、发展现状、网络结构、层次模型、关键技术和应用每几个方面。     

A rapid and sensitive method for determination of theophylline in plasma and saliva by high pressure liquid chromatography

A fast and sensitive high pressure liquid chromatographic method for the monitoring of theophylline concentrations in plasma or saliva was developed. Each sample requires only about 15 minutes for the completion of the assay after receiving the plasma or saliva sample. Only 0.1 ml of sample is required, and concentrations as low as 1 mcg/ml can be accurately measured.     

Sensitivity of Staphylococcus aureus to unsaturated fatty acids

Some unsaturated fatty acids were found to inhibit the growth of Staphylococcus aureus. Their effectiveness was related both to the degree of unsaturation and to the configuration of the molecule about the double bonds. Both linoleic acid and linolenic acid increased the proportion of plasmid-negative bacteria in a growing culture of bacteria containing a penicillinase plasmid. This was not due to a 'curing' effect of the fatty acids but was the result of greater sensitivity of the growth of bacteria containing penicillinase plasmid to inhibition by the unsaturated fatty acids. The presence of a plasmid conferring resistance to tetracycline, however, did not make the bacterium more sensitive to inhibition by linoleic or linolenic acids.