RADIOSENSITIVITY AND CELLULAR MOLECULAR EFFECTS

这项研究的目的是评估DNA中的事件序列， 体外培养哺乳动物细胞的细胞遗传学损伤和细胞死亡 在卤代嘧啶（HP）（主要是BrdUrd和IdUrd）的存在下， 临床上可达到的浓度。假设惠普 使细胞对辐射损伤敏感， 致死性损伤（PLD）。这种细胞固定过程将与 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。将使用转化的（CHO，TCL-15）进行研究 和非转化的（10T1/2）细胞系作为肿瘤的体外模型， 正常组织。在细胞水平上，HP掺入 DNA将与生长控制机制的放松相关，并且 在生长对比中，辐射存活曲线的D0和Dq的修改。 非生长细胞以及在细胞的各个阶段被照射的细胞中 周期PLD修复损害放射增敏的可能性 将检查HP引起的感染。 关于IdUrd诱导的知之甚少 在这里检查的终点的放射增敏。将进行比较 BrdUrd和IdUrd介导的放射增敏作用之间的关系， 辐射后用阿糖胞苷和咖啡因处理引起的杀伤。在 在染色体水平上，辐射诱导的染色体损伤将是 通过在高原中的早熟染色体凝集（PCC）技术测定- 在HP存在下生长的G1期或同步的G1期细胞。一 将建立胸苷替代量与 HP和PCC片段的修复率以及错修复量 诱导（环和双着丝粒）。一个类似的关系使用染色体 在中期经典测量的畸变将在 辐照的平台期细胞和同步化并辐照的细胞， 细胞周期的各个阶段。在染色体水平上的修复（PCC） 与在类似条件下观察到的PLD修复进行比较， 将在细胞杀伤和染色体损伤之间建立相关性。 在DNA水平，DNA损伤和修复（总断裂和双链断裂） 特别是断裂）将在指数生长的细胞中测量， 平台期细胞，和细胞同步化在G1-，S-和G2 + M-期，作为一个 HP公司的功能。将建立一种关系， HP替代胸苷的量与DNA损伤的诱导和修复 和残余损伤

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.