MDR1, cholesterol certification and cell growth: a comparative study in normal and multidrug-resistant KB cell lines

The product of the MDR1 gene (P-gp) has been implicated in the transport of cholesterol from plasma membrane to endoplasmic reticulum for esterification. In previous studies on leukemia cell lines, we suggested that cholesterol esterification may regulate the rate of cell growth and that the MDR1 gene might be involved in this process by modulating intracellular cholesterol esters levels. To further investigate this matter, the rate of cell growth, cholesterol metabolism, expression of the MDR1 gene, and P-gp activity were compared in KB cell lines displaying differences in expression and function of P-gp (drug-sensitive phenotype versus MDR phenotype). The rate of cell growth correlated with cholesterol esterification in all KB cell lines, whereas the over-expression of MDR1 observed in the MDR cell lines was not always associated with an increased capacity of cells to esterify cholesterol. Two known inhibitors of P-gp activity, progesterone and verapamil, strongly inhibited both cholesterol esterification and cell proliferation in all KB cell lines, but they affected intracellular accumulation of labeled vinblastine only in MDR cell lines. These results further support a role for cholesterol esters in the regulation of cell growth and suggest that the P-gp expressed in MDR KB cells is not involved in the general process leading to cholesterol esterification. Received 14 February 2000; received after revision 10 April 2000; accepted 8 May 2000     

重氮去氮反应在S_N中的溶剂效应

以 2 ,4 二甲基 6 硝基乙酰苯胺为起始原料 ,用乙醇作还原剂合成了 3,5 二甲基硝基苯 ;给出　了产物光谱分析和高压液相色谱分析数据 ;分析重氮去氮反应在酸性介质中的溶剂效应并提出在浓酸溶液中 ,当　酸度函数H0 =- 3.5时生成物产率最好     

三羟甲基甲胺固-固相变的变温红外光谱研究

在４０００～４５０ｃｍ＾－１波段范围内测定了三羟甲基胺（ＴＡＭ）在２０～１４０℃的红外光谱。研究发现，在１３０～１３５℃区间内，ＴＡＭ的特征吸收峰的位置、形状、强度均发生较大变化，该温度区间与ＴＡＭ的固－固相变温度１３４．７３℃相对应。研究结果可以验证ＴＡＭ的固－固相变相理。     

一种抗野值的Kalman滤波器

在目标跟踪系统中,由于杂波的存在,往往使跟踪检测数据中含有大量、成片的野值,造成系统跟踪精度下降。本文通过对检测数据中新息特性的分析,给出了检测数据中野值的判定方法,通过重新构造状态估计来消除野值的影响。仿真结果证明了该方法可有效的剔除野值,提高跟踪系统的跟踪精度。     

Visual Basic程序设计课程教学探讨

分析了VisualBasic程序设计课程的特点，对该课程教学手段，教学方法的改进，及教学内容的完善等方面作了一些探索和实践。     

机车自动鸣笛系统

机车自动鸣笛系统是在监控装置及机车安全信息综合监测装置的基础上，根据实际行车安全运输的需要，利用工控原理，采用目前成熟的单片机技术研制开发的一个单元控制系统。简要介绍了该系统的控制原理、系统功能扩展以及主要采取的抗干扰措施等。     

Effect of acriflavine on the radiation resistance enhancement induced by cysteine treatment inEscherichia coli B/r

Zusammenfassung Zur Prüfung der Strahlenresistenz vonEscherichia coli nach bewährter Methode wird Acriflavin, ein DNA-Reparaturhemmer, zugegeben und es wird festgestellt, dass die Strahlenresistenz auch unter Cysteinschutz sinkt.