辐射诱发的基因组不稳定性

辐射诱发的基因组不稳定性１引言与辐射致癌有关的遗传学上的影响因素及渐成机制已有论述（ＣＯＸ１９９４），在这些机制中，最近感兴趣的焦点是基因组不稳定性规律可能在辐射致癌中所起的作用，业已提出，辐射照射“记忆”的传递给子代细胞的几率可能会增加，或者在肿瘤...     

CB法微核检测技术应用于诱导基因组不稳定性的研究

对γ射线诱导中国仓鼠成纤维(CHL)细胞基因组不稳定性进行了研究。利用CB法微核检测技术对一次照射、二次照射的CHL细胞进行微核测定,观察DNA损伤程度的变化情况。结果显示,微核发生率与细胞受照剂量呈相关关系,并随培养时间延长呈下降趋势。细胞再次受照后,其微核发生率与一次受照剂量呈相关关系。表明微核发生率与染色体损伤程度存在剂量相关性,微核检测技术可以用于生物效应表现为染色体损伤的辐射诱导基因组不稳定性的研究。     

DNA-PKcs基因组不稳定性和辐射超敏感性

本研究旨在揭示DNA-PKcs(DNA损伤修复的关键酶之一)与基因组不稳定性、辐射超敏感性的关系。以人神经胶质瘤细胞系M059K(DNA-PKcs野生型)和M059J(DNA-PKcs缺陷型)为实验模型,用常规克隆形成法测定细胞存活率、cytochalasin-B(细胞松弛素B)阻断-微核法跟踪克隆形成过程中基因组不稳定性变化。实验结果表明,存在辐射超敏感性的DNA-PKcs野生型细胞M059K在0.2Gy辐照后随着培养时间的延长基因组不稳定性与0.6Gy辐照水平一致;不存在辐射超敏感性的DNA-PKcs缺失型细胞M059J经0.6Gy辐照后,基因组不稳定性水平明显高于0.2Gy辐照。这些结果提示,DNA-PKcs可能是导致辐射超敏感性的关键因素之一。     

基因组不稳定性与辐射致癌

辐射可以诱导受照细胞及子代基因组不稳定性的发生。基因组不稳定性导致基因的突变率增加,并通过多种机制致癌。本文简要介绍了基因组不稳定性的可能机制,及其在辐射致癌中的作用。     

线粒体基因组及其在辐射生物学中的研究进展

线粒体DNA是人类细胞中唯一核外遗传物质,缺乏组蛋白的保护和DNA修复系统,对辐射等氧化损伤更敏感。综述了近年来线粒体DNA与辐射敏感性、辐射剂量效应关系、辐射致突变以及肿瘤等领域的探索性研究,并就线粒体DNA研究技术在辐射生物学领域的应用前景进行阐述。     

RAN基因沉默对辐射诱发基因组不稳定肝细胞HL-7702凋亡及细胞周期的影响

为研究RAN基因沉默对基因组不稳定肝细胞凋亡及细胞周期的影响,利用慢病毒介导的RNA干扰(RNAi)技术沉默基因组不稳定肝细胞中RAN基因的表达,通过流式细胞术检测RAN基因沉默后基因组不稳定肝细胞的凋亡率及细胞周期。实时荧光定量PCR检测表明,RAN siRNA能有效沉默RAN基因mRNA的转录(p0.01);流式细胞术检测表明,RAN基因沉默诱发基因组不稳定肝细胞G0/G1期细胞增加(p0.05),发生G1期阻滞,同时,细胞凋亡率较阴性对照组明显降低(p0.01)。说明RAN基因可能通过参与周期调控及促进细胞凋亡进而维持肝细胞基因组的稳定性。     

肿瘤分子遗传学新方法—比较基因组杂交

比较基因组杂交是近年来在荧光原位杂交基础上发展起来的一种新的分子遗传学方法，具有一次实验可在全部染色体或染色体亚区水平上对整个基因组内ＤＮＡ物质的增加或减少进行分析，且标本来源不受限制，不需进行肿瘤细胞培养等优点，已广泛用于各种肿瘤和遗传性疾病的检测。     

线粒体基因组D-loop区变异及辐射诱发突变

线粒体基因组D环区作为非编码区,控制着mtDNA的复制与转录,由于自身的结构和功能特点,极易发生变异.变异形式包括突变和多态性,这些变异在疾病的发生和发展过程中起着非常重要的作用.此外,本文还简要介绍了辐射诱导的D环区突变的研究现状及其前景.     

电离辐射诱发的基因组不稳定性和旁效应

近10年来,对于基因组不稳定性和旁效应的研究已成为生物学和放射生物学领域的一个热点。随着对辐射损伤研究的深入,电离辐射引起的非靶效应（如基因组不稳定性、旁效应等）将对与辐射照射有关的危险评价提出新的挑战。本文就体内、外电离辐射诱发的基因组不稳定性,体内、外旁效应以及二者之间的关系做一简要概述。     

不同剂量γ射线照射诱发CHL细胞基因组不稳定性的研究

采用单细胞凝胶电泳技术和微核检测技术对60Coγ射线照射诱发中国仓鼠肺细胞(CHL细胞)产生的直接效应、基因组不稳定性进行了初步探讨.将对数生长期的细胞分成不同的剂量组,经γ射线照射后,对受照存活细胞进行单细胞凝胶电泳(SCGE)和微核发生率(MF)的测定.同时,将一部分受照存活细胞继续传代培养,待其传至33代时,再给予2 Gy的照射剂量进行二次照射,然后再进行单细胞凝胶电泳和MF的测定.结果表明,首次照射剂量与子代二次照射后的损伤程度存在剂量-效应关系.本实验为探讨辐射诱发基因组不稳定性的研究提供了实验基础.     

放射性核素标记靶向肿瘤新生血管分子探针研究进展

分子影像技术能够在细胞及分子水平定性、定量示踪肿瘤新生血管生物学过程.不同的放射性核素标记靶向分子探针在肿瘤新生血管显像过程中发挥着至关重要的作用.系统介绍了目前应用于肿瘤新生血管功能显像的分子探针,包括抗体及其片段、多肽探针、纳米颗粒探针等.纳米颗粒探针因具有不穿透血管内膜的性质,是目前研究较多的肿瘤新生血管靶向探针.肿瘤新生血管显像剂的体内稳定性及生物相容性、靶向结合于肿瘤新生血管的效率及药代动力学性质是目前亟待解决的问题.     

Elements and their transitions feasible for NEET

Electron and nuclear transitions in the nuclear excitation by electron transition (NEET) process have been investigated. The NEET transitions for nuclei are presented in a table in which the electron and nuclear transitions, their transition energies, transition multipoles, and nuclear spin angular momentum are given. The elements are listed for which the difference between the electron and nuclear transition energy is <5 keV, because the NEET probability will be appreciable if the electron transition energy is close to the nuclear transition one. As both the experimental and theoretical studies for NEET are at an early stage, only the elements and their parameters related to NEET are listed here. The present compilation, however, provides a useful direction for future studies of NEET and its applications to nuclear science.     

CFD simulations of hydrogen combustion in a simplified EPR containment with CFX and REACFLOW

The prediction of over-pressures and temperatures that are generated by hydrogen explosions in case of a severe nuclear accident is a crucial stage of the safety analysis of the containment. The investigation presented in this paper is a continuation of the numerical studies of validation and benchmarking that were carried out in the European co-sponsored project HYCOM. In the present work, numerical simulations of hydrogen deflagrations within a simplified, real-scale European Pressure Reactor (EPR) containment have been performed with two CFD codes, CFX4 and REACFLOW. The analysis has been focused not only on overpressure peaks and pressure oscillations, but also on pressure differences between the two sides of the same wall of internal compartments. Different geometrical configurations have been considered in term of presence of vents between internal compartments and in term of vents number, size and position. Single and multiple ignition points have also been taken into account. The paper describes the main results of the investigation and it is a demonstration of how CFD modelling can provide significant indications for real-scale safety applications within the limits of uncertainty of the accident scenarios.     

Single event upset tests of an 80-Mb/s optical receiver

This paper studies the single event upset (SEU) sensitivity of a radiation-tolerant 80-Mb/s receiver developed for the CMS Tracker digital optical link. Bit error rate (BER) measurements were made while irradiating the receiver with protons and neutrons at different beam energies and incident angles and for a wide range of optical power levels in the link. Monte Carlo simulations have also been used to assist in the interpretation of the experimental results. As expected, the photodiode is the most sensitive element to SEU. The fake signal induced by direct ionization dominates the bit-error cross-section only for protons incident on the photodiode at large angles and low levels of optical power. Comparison of the neutron and proton bit-error cross-sections demonstrates that nuclear interactions contribute significantly to the proton-induced SEU errors and that they will dominate the radiation-induced error rate in the real Tracker application     

滚环DNA扩增技术及其应用

滚环扩增技术是一种等温信号扩增方法,DNA可在很短时间内实现指数扩增,因此,可用于痕量分子的检测.目前,该技术既可以扩增环状DNA、RNA,也可以扩增线性DNA,甚至全基因组DNA.目前,该技术主要用于全基因组扩增、核酸测序、单核苷酸多态性以及DNA芯片、蛋白质芯片分析等广泛领域.     

What is the potential use of thorium in the future energy production technology?

Today's nuclear technology has principally been based on the use of fissile U-235 and Pu-239. While the natural thorium isotope Th-232 can finally be transformed to a fissile U-233 nucleus following a thermal neutron capture reaction, the existence of thorium in the nature and its potential use in the nuclear technology were not unfortunately into account with a sufficient importance. This was probably because of the geological availability of natural resources of thorium and uranium. Global distributions of thorium and uranium reserves clearly indicate that in general some developed countries such as the USA, Canada, Australia have considerable uranium reserves and contrarily only some developing countries such as Brazil, Turkey, India, Egypt have considerable thorium reserves as being totally about 70 % of the global reserve. All technical parameters obtained from the studies on thorium fuel cycle during the last 50 years indicate that thorium fuel cycle can be used in most of reactor types already operated. In addition, accelerated-driven hybrid systems promise to use the thorium based nuclear fuels. So, thorium will probably be a nuclear material much more valuable than uranium in the future. For this reason, all developing countries having thorium reserves should focus their technological attentions to the evaluation of their national thorium resources like in the case of India. In this paper a brief story on the studies of thorium and its potential use in the future energy production technology have been summarized.     

脉冲射线束探测技术(续)

3.契仑可夫探测器 高能物理实验中大量使用各种契仑可夫探测器,在脉冲射线束测量中也常使用这种探测器,它由契仑可夫辐射体和光电倍增管(或光电管)组成。 脉冲射线束测量中常用有机玻璃为契合可夫辐射体。透明液体作为契合可夫辐射体使用不如固体辐射体方便,用得较少。     

模糊逻辑控制在核动力系统中的应用和问题探讨

模糊逻辑控制(FLC)在核动力系统中的应用研究表明、FLC对核动力系统的智能化和全自动化控制而言,是一种有效而可行的先进控制方法。本文对此方面的研究成果进行了全面回顾和总结,并探讨了FLC应用研究和实践中需要重点解决的问题。