Regulation of cell adhesion by PP2A and SV40 small tumor antigen: An important link to cell transformation

The serine/threonine protein phosphatase 2A (PP2A) represents a large family of highly conserved heterotrimeric enzymes. Their critical importance in cell homeostasis is underlined by the fact that they are targets of natural toxins like the tumor promoter okadaic acid, and of simian virus 40 small tumor antigen (SV40 small t), a viral protein known to promote cell transformation. Furthermore, mutated or lower expression levels of PP2A subunits have been found in certain cancers. One major known event in PP2A-dependent cell transformation is the alteration of key signaling pathways that control cell growth and survival. In this review, we focus on how PP2A enzymes also affect cell adhesion and cytoskeletal dynamics, the disruption of which is linked to loss of cell polarity, increased cell motility and invasiveness. We also examine how those various pathways participate in the transforming activity of SV40 small t. Received 29 June 2006; received after revision 3 August 2006; accepted 20 September 2006     

热处理工艺参数对40CrNiMoA钢涡轮轴力学性能的影响

现通过工艺和性能试验探讨了热处理工艺参数对40CrNiMoA钢涡轮轴力学性能的影响,结果表明：采用上限温度淬火的调质工艺可使涡轮轴具有更高的强度和韧性水平。     

FSD-40DME电源模块故障导致监控失效的分析

测距仪是国际民航组织规定的近程导航设备,它提供航空器相对于地面测距仪台的斜距。当测距仪与仪表着陆系统配合使用时,测距仪可以替代指点信标,以提供飞机进近和着陆的距离信息。本文在此介绍FSD-40型号测距仪电源模块故障导致监控失效的实例,讲解TPS模块与各板件之间的相互关系,为该型号设备的维护维修人员提供一些借鉴。     

A very strong summer monsoon event during 30-40 kaBP in the Qinghai-Xizang (Tibet) Plateau and its relation to precessional cycle

Guliya ice core records, high lake-level records in the Qinghai-Xizang Plateau and at its north side as well as vegetation succession records indicated that during the period of 30-40 kaBP, namely the later age of the megainterstadial of last glacial period, or the marine oxygen isotope stage 3, the climate of the Qinghai-Xizang Plateau was exceptionally warm and humid, the temperature was 2-4℃ higher than today and the precipitation was 40% to over 100% higher than the current average, all these suggested the existence of an exceedingly strong summer monsoon event. It has been inferred that the occurrence of such an event was attributed, on the one hand, to the stronger summer low pressure over the Plateau, which strengthened the attraction to the summer monsoon; on the other hand, to the vigorous evaporation of the tropic ocean surface, which promoted the moisture-rich southwest monsoon to flow over the Qinghai-Xizang Plateau. The background responsible for the formation of the very strong summer monsoon was that the period of 30-40 kaBP was just in the strong insolation stage of the 20ka precessional cycle, when the Qinghai-Xizang Plateau received extraordinary strong solar radiation and thus enlarged the thermodynamical contrast between the Plateau and the mid-south part of the Indian Ocean.     

JBP 40径向柱塞泵配油轴与转子配合间隙的研究

径向柱塞泵配油轴与转子配合间隙直接影响着泵的性能和寿命。本文通过理论计算和实验结果分析得出ＪＢＰ４０ 泵的最佳取值范围。     

慢病毒载体介导SV40LT致人脐静脉内皮细胞永生化

为成功分离与鉴定人原代脐静脉内皮细胞,用猿猴病毒40大T抗原(SV40LT)异位表达建立永生化人脐静脉内皮细胞系。将含SV40LT cDNA片段的慢病毒载体,转染人原代脐静脉内皮细胞,连续传代培养。通过形态、细胞免疫组织化学、RT-PCR及管状成形试验进行原代及转染后细胞形态学和功能学鉴定及检测SV40大T抗原表达。结果SV40LT转染后的人脐静脉内皮细胞为扁平多角形或短梭状,呈单层铺路石状镶嵌排列。特异性表达Ⅷ因子、KDR、SV40LT表达,并具有管状成型能力。说明成功分离与鉴定永生化的脐静脉内皮细胞系,为后续血管靶向治疗奠定了基础。     

吐温40及其复配缓蚀剂在原油模拟液中对20 号碳钢的缓蚀性能研究

通过采用失重法、CMB-4510A缓蚀剂快速评定仪、极化曲线法和交流阻抗法研究了在酸性体系溶液中吐温40、硫酸锌、葡萄糖酸钠三种缓蚀剂单独使用及以吐温40为主的二元复配体系对20号碳钢在酸性体系中的缓蚀效果。实验结果表明:温度为30℃,p H值为4时,吐温40可以很好地抑制20号钢的腐蚀;而且吐温40与硫酸锌、葡萄糖酸钠的复配缓蚀剂具有良好的增效作用。     

H_4PMo_(11)VO_(40)催化氧化2-甲基萘制备甲萘醌

以磷钼钒杂多酸H4PMo11V1O40为催化剂、乙酸为溶剂,用双氧水氧化2-甲基萘制备2-甲基萘醌.实验表明:H4PMo11V1O40具有一定的催化活性.通过正交试验和单因素试验考察了催化剂用量、乙酸用量、双氧水用量、反应时间、反应温度等对收率的影响,获得较佳的合成条件:杂多酸∶2-MN(质量比)=7%,乙酸∶2-MN(质量比)=10.5∶1,双氧水∶2-甲基萘(摩尔比)=4.2∶1,较适宜的温度为40~50℃,反应时间为30 min.