RADIOSENSITIVITY AND CELLULAR MOLECULAR EFFECTS

这项研究的目标是评估DNA中的事件序列 细胞遗传学损伤对体外培养哺乳动物细胞死亡的损伤 在卤代嘧啶(Hp)(主要是BrdUrd和IdUrd)存在的情况下 临床上可以达到的浓度。假设是惠普 通过增强潜在的固定使细胞对辐射损伤敏感 致命性损害(PLD)。这一细胞固定过程将与 染色体损伤的固定和错误修复以及修复抑制事件 在DNA水平上。将对Transform(CHO，TCL-15)进行研究 和未转化(10T1/2)细胞系作为体外肿瘤模型和 分别为正常组织。在细胞水平上，将HP整合到 DNA将与生长控制机制的放松相关，以及 辐射存活曲线D_0和D_q的修正。 不生长的细胞以及在细胞的不同阶段受到照射的细胞 周而复始。PLD修复影响放射增敏的可能性 将检测由Hp诱导的。关于IdUrd诱导的信息知之甚少 在这里检查的终点的放射增敏。我们会做一个比较 BrdUrd和IdUrd介导的放射增敏和增强 辐射后用阿糖胞苷和咖啡因治疗引起的死亡。在 染色体水平上，辐射诱导的染色体损伤将是 用染色体过早凝聚(PCC)技术对高原地区的 在Hp存在下生长的G1期细胞或同步化的G1期细胞。一个 将建立胸腺嘧啶核苷量之间的关系 Hp和PCC片段的修复率以及误修复量 诱导(环和双着丝粒)。使用染色体的相似关系 在中期经典测量的像差将被建立在 辐照平台期细胞和同步辐射的细胞 细胞周期的不同阶段。染色体水平的修复(PCC)将 与在类似条件下观察到的PLD修复和 将建立细胞杀伤和染色体损伤之间的相关性。 在DNA水平上，DNA损伤和修复(完全断裂和双链 具体而言)将在指数增长的细胞中测量， 平台期细胞，同步于G1期、S期和G2+M期的细胞作为 幽门螺杆菌的作用。将在两国之间建立关系 幽门螺杆菌替代胸腺嘧啶核苷量与DNA损伤的诱导和修复 以及残存的损伤。

The goal of this research is to evaluate the sequence of events from DNA damage to cytogenetic damage to cell death in mammalian cells grown in vitro in the presence of halogenated pyrimidines (HP) (mainly BrdUrd and IdUrd) at concentrations that are clinically achievable. The hypothesis is that HP sensitize cells to radiation damage by enhancing fixation of potentially lethal damage (PLD). This cellular fixation process will be related to fixation and misrepair of chromosome damage and to repair inhibition events at the DNA level. Studies will be carried out with transformed (CHO,TCL-15) and nontransformed (10T1/2) cell lines as in vitro models for tumor and normal tissue, respectively. At the cellular level, incorporation of HP into DNA will be correlated with relaxation of growth control mechanisms, and modification of the D0 and Dq of the radiation survival curve in growing vs. nongrowing cell as well as in cells irradiated in various phases of the cell cycle. The possibility that repair of PLD compromises radiosensitization induced by HP will be examined. Very little is known about IdUrd-induced radiosensitization at the endpoints examined here. A comparison will be made between BrdUrd and IdUrd mediated radiosensitization and the enhancement of killing caused by post-irradiation treatment with araA and caffeine. At the chromosome level, the induction of chromosome damage by radiation will be assayed by the Premature Chromosome Condensation (PCC) technique in plateau- phase or synchronized G1-phase cells grown in the presence of HP. A relationship will be established between the amount of thymidine replaced by HP and rate of repair of PCC fragments as well as amount of misrepair induced (rings and dicentrics). A similar relationship using chromosomal aberrations as classically measured at metaphase will be established in irradiated plateau-phase cells and cells synchronized and irradiated at various phases of the cell cycle. Repair at the chromosome level (PCC) will be compared to the repair of PLD observed under similar conditions and a correlation will be established between cell killing and chromosome damage. At the DNA level, DNA damage and repair (total breaks and double-strand breaks specifically) will be measured in exponentially growing cells, plateau-phase cells, and cells synchronized in G1-, S-, and G2+M-phase as a function of HP incorporation. A relationship will be established between amount of thymidine replaced by HP and induction and repair of DNA damage and residual damage.