RADIOSENSITIVITY PROGNOSIS BASED ON DNA REPAIR ASSAY

本程序将使用最新开发的粘弹性测量方法 (Ve)测量大小、构象和浓度(数量) 哺乳动物的染色体DNA分子。通过比较分子的变化 大小(Gamma)、构象(相对Tau和Gamma)和大小浓度 (Ri)分布，作为辐射剂量和辐射后的函数 治疗和/或修复、双支架诱导率和修复率 将确定中断(DSB)。细胞生殖完整性丧失 将与每个单元的未修复DSB进行关联，以便确定 未修复的DSB是主要的致死性病变。如果这种关联 证明意义重大，这是基于DNA的细胞分析的基础 辐射敏感度将会被确定。由于VE可以检测到 临床(和生物)相关剂量(0.50-20Gy)的影响 上述关系将为临床提供有用的分析方法。这个化验 将在这项提案的竞争性更新中进行测试。 此外，几个生物学上重要的点将由 我们计划收集的数据。其中第一个是确定为 哺乳动物的染色体DNA是由线形还是环状组成 分子。目前存在直接证明DNA的NOK数据 构象。我们建议收集的数据将证明 哺乳动物松弛的染色体DNA的线形或环状 细胞。这对我们理解 染色体结构。第二点将是确定一个 D37、DSB和分子的通用测定方法 通过使用VE进行整合。第三点将是对 假设细胞存活曲线的形状可以解释 仅就潜在致命损伤(PLL)及其修复而言。我们 将研究辐射后修复时间的影响 高渗治疗，看看细胞存活曲线是否符合这一点 得到了解释。这已经在一个细胞系中完成了，但它是 不清楚这是否是一个普遍的发现。第四点将是 每次治疗后未修复的DSB数量的测定 用来评估PLL，以及测试PLL是否可以与 DSB。

This program will use the recently developed method of viscoelastometry (VE) to measure the size, conformation, and concentration (number) of mammalian chromosomal DNA molecules. By comparing changes in molecular size (Gamma), conformation (relative Tau and Gamma), and size concentration (ri) distribution, as functions of radiation dose and postirradiation treatment and/or repair, the rates of induction and repair of double-stand breaks (DSBs) will be determined. Cellular loss of reproductive integrity will be correlated with unrepaired DSBs per cell in order to determine if the unrepaired DSB is the major lethal lesion. Should such a correlation prove significant, the basis for a DNA based assay for cellular radiosensitivity will have been established. Since VE can detect the effects of clinically (and biologically) relevant doses (0.50 - 20 Gy), the above relationship will then provide a useful clinical assay. This assay will be tested in a competing renewal of this proposal. In addition, several biologically important points will be established by the data we propose to collect. The first of these is a determination as to whether mammalian chromosomal DNA consists of linear or circular molecules. At present nok data exist which directly demonstrate the DNA conformation. The data we propose to collect will demonstrate either the linear or the circular nature of relaxed chromosomal DNA in mammalian cells. This has far reaching consequences for our understanding of chromosome structure. The second point will be the determination of a general method for the determination of the D37, DSB and molecular conformation by the use of VE. The third point will be a test of the hypothesis that the shapes of the cell survival curves can be explained solely in terms of potentially lethal lesions (PLL) and their repair. We will examine the effects of postirradiation repair time followed by hypertonicity treatment to see if cell survival curves consistent with this interpretation are obtained. This has been done in one cell line but it is not clear if this is a general finding. The fourth point will be the determination of the number of unrepaired DSBs after each of the treatment used to assess PLL, and a test as to whether the PLL can be correlated with the DSB.