A point mutation in the neu oncogene mimics ligand induction of receptor aggregation

The rat neu gene, which encodes a protein closely related to the epidermal growth factor receptor, is a proto-oncogene that can be converted into an oncogene by a point mutation. Both genes encode proteins with a relative molecular mass of 185,000 but the question of why the neu gene product, p185neu, is oncogenic, whereas the product of c-neu, p185c-neu, is not, remains unanswered. The proteins have several features common to the family of tyrosine kinase growth-factor receptors, including cysteine-rich external domains, a hydrophobic transmembrane region and a cytoplasmic tyrosine kinase domain. The oncogenic p185neu differs from p185c-neu by an amino-acid substitution in the transmembrane region of the glycoprotein: this replacement of valine by glutamic acid at position 664 induces increased intrinsic tyrosine kinase activity which is associated with transformation. Many glycoproteins with charged amino acids in the transmembrane region exist as multimeric complexes at the plasma membrane. We have therefore investigated the association state of both products of the neu gene and show that the oncoprotein p185neu is organized at the plasma membrane primarily in an aggregated form, but that p185c-neu is not. Induction of an aggregated state may mimic aspects of ligand-induced receptor aggregation resulting in enzymatic activation that leads to cellular transformation.     

图书财产号两种印制方法的比较研究

介绍了图书馆图书财产号印制方法的两次变革,探讨了两种印制方法的影响因素,比较了两种印制方法的优点及不足,指出使用不干胶的条形码取代财产号是图书馆藏与时俱进的必然选择。     

杏花雨对血管性痴呆大鼠行为及其海马Bcl-2,Bax蛋白表达的影响

为研究杏花雨对血管性痴呆大鼠行为学及大鼠海马Bcl-2,Bax蛋白表达的影响,采用反复缺血再灌注+硝普钠方法复制出血管性痴呆(VD)动物模型,并观察银杏黄酮注射制剂杏花雨对VD大鼠的保护作用,采用Morris水迷宫检测其行为学,免疫组织化学法检测并观察其海马Bcl-2,Bax蛋白表达.研究结果显示:与假手术组相比,模型组大鼠Bcl-2,Bax蛋白表达增加(P<0.01),Bcl-2/Bax(阳性细胞数比值)显著降低,经杏花雨a,b及金纳多治疗后,与模型组相比,VD大鼠认知能力显著改善(P<0.01),海马CA1区Bcl-2阳性细胞数均有提高(P<0.05),杏花雨b组有明显提高(P<0.01);大鼠海马CA1区Bax阳性细胞数降低,尤其以杏花雨b组降低明显(P<0.01),Bax/Bcl-2也较假手术组与模型组明显提高(P<0.05).结果表明杏花雨可以改善血管性痴呆大鼠的认知能力,推测与Bcl-2,Bax蛋白表达有关.     

翻转课堂下无机非金属材料专业课程教学与考核方法研究

探索了翻转课堂模式下无机非金属材料专业课程的教学与考核方法.设计了10 min线上微课+30 min课堂小组讨论+20 min师生互动总结的教学方法.成绩考核注重过程,期中考试成绩占20%,期末考试成绩占40%,平时考核成绩占40%.实践证明,该教学和考核方法有助于鼓励学生自主学习,可提高教学质量和学生的综合素质.     

Enhancement of the high-magnetic-field critical current density of superconducting MgB2 by proton irradiation

Magnesium diboride, MgB2, has a relatively high superconducting transition temperature, placing it between the families of low- and high-temperature (copper oxide based) superconductors. Supercurrent flow in MgB2 is unhindered by grain boundaries, making it potentially attractive for technological applications in the temperature range 20-30 K. But in the bulk material, the critical current density (Jc) drops rapidly with increasing magnetic field strength. The magnitude and field dependence of the critical current are related to the presence of structural defects that can 'pin' the quantized magnetic vortices that permeate the material, and a lack of natural defects in MgB2 may be responsible for the rapid decline of Jc with increasing field strength. Here we show that modest levels of atomic disorder induced by proton irradiation enhance the pinning of vortices, thereby significantly increasing Jc at high field strengths. We anticipate that either chemical doping or mechanical processing should generate similar levels of disorder, and so achieve performance that is technologically attractive in an economically viable way.     

云南城市化目标的设定与战略选择

随着第二步战略目标的基本实现，我国的社会经济发展已经进入到全面建设小康社会的崭新的阶段，这个阶段意味着我国城乡生产力布局和人口的空间分布都会发生有史以来规模最大、最为深刻的变迁。全面建设小康社会的奋斗目标具有丰富的内涵，涉及广泛而丰富的社会经济结构，而推动城市化进程则是其重要内容之一。云南是一个欠发达的农业大省，农业劳动多，农村人口比重大，如何推进城市化，必须根据云南的实际，制定正确的城市化目标和发展战略。     

双复合Poisson风险模型的赤字尾概率

研究双复合Poisson过程的风险模型,得到了关于赤字尾概率的函数型不等式,并且作为它的应用,得到了一些指数型上界估计,使得某些已有结果得到推广.     

The molecular mechanism by which insulin stimulates glycogen synthesis in mammalian skeletal muscle

The ability of insulin to promote the phosphorylation of some proteins and the dephosphorylation of others is paradoxical. An insulin-stimulated protein kinase is shown to activate the type-1 protein phosphatase that controls glycogen metabolism, by phosphorylating its regulatory subunit at a specific serine. Furthermore, the phosphorylation of this residue is stimulated by insulin in vivo. Increased and decreased phosphorylation of proteins by insulin can therefore be explained through the same basic underlying mechanism.     

一维正弦型函数光子晶体带隙结构研究

我们提出一种函数型光子晶体,其折射率是一个随空间位置周期性变化的函数.基于费马原理,我们得到了光在一维函数型光子晶体中的运动方程,并利用传输矩阵的方法推导出光在一维函数光子晶体的色散关系、发射率和透射率.通过理论模拟发现,介质的折射率、半周期厚度以及入射角对光子晶体带隙变化有重要的影响.