Morris G M, Coderre J A, Hopewell J W, Micca P L, Rezvani M
CRC Normal Tissue Radiobiological Research Group, University of Oxford, UK.
Radiother Oncol. 1994 Aug;32(2):144-53. doi: 10.1016/0167-8140(94)90101-5.
The effects of boron neutron capture irradiation employing either BPA or BSH as neutron capture agents has been assessed using the dorsal skin of Fischer 344 rats. Pharmacokinetic studies, using prompt gamma spectrometry, revealed comparable levels of boron-10 (10B) in blood and skin after the intravenous infusion of BSH (100 mg/kg body wt.). The 10B content of blood (12.0 +/- 0.5 micrograms/g) was slightly higher than that of skin (10.0 +/- 0.5 micrograms/g) after oral dosing with BPA. Biphasic skin reactions were observed after irradiation with the thermal neutron beam alone or in combination with BPA or BSH. The time of onset of the first phase of the skin reaction, moist desquamation, was approximately 2 weeks. The time at which the second-wave skin reaction, dermal necrosis, became evident was dose-related and occurred after a latent interval of > or = 24 weeks, well after the acute epithelial reaction had healed. The incidence of both phases of skin damage was also dose-related. The radiation doses required to produce skin damage in 50% of skin sites (ED50 values) were calculated from dose-effect curves and these values were used to determine relative biological effectiveness (RBE) and compound biological effectiveness (CBE) factors for both moist desquamation and dermal necrosis. It was concluded on the basis of these calculations that the microdistribution of the two neutron capture agents had a critical bearing on the overall biological effect after thermal neutron activation. BSH, which was possibly excluded from the cytoplasm of epidermal cells, had a low CBE factor value (0.56 +/- 0.06) while BPA, which may be selectively accumulated in epidermal cells had a very high CBE factor (3.74 +/- 0.7). For the dermal reaction, where vascular endothelial cells represent the likely target cell population, the CBE factor values were comparable, at 0.73 +/- 0.42 and 0.86 +/- 0.08 for BPA ad BSH, respectively.
利用费希尔344大鼠的背部皮肤，评估了使用双丙叉丙酮（BPA）或硼酸钠（BSH）作为中子俘获剂的硼中子俘获辐照的效果。使用瞬发伽马能谱法进行的药代动力学研究表明，静脉输注BSH（100mg/kg体重）后，血液和皮肤中的硼 - 10（¹⁰B）水平相当。口服BPA后，血液中的¹⁰B含量（12.0±0.5微克/克）略高于皮肤中的含量（10.0±0.5微克/克）。单独用热中子束或与BPA或BSH联合辐照后，观察到皮肤出现双相反应。皮肤反应第一阶段即湿性脱屑的开始时间约为2周。第二波皮肤反应即真皮坏死明显出现的时间与剂量相关，且在≥24周的潜伏期后发生，此时急性上皮反应已愈合。皮肤损伤两个阶段的发生率也与剂量相关。根据剂量 - 效应曲线计算出50%皮肤部位产生皮肤损伤所需的辐射剂量（ED50值），并使用这些值来确定湿性脱屑和真皮坏死的相对生物效应（RBE）和复合生物效应（CBE）因子。基于这些计算得出的结论是，两种中子俘获剂的微观分布对热中子活化后的整体生物学效应具有关键影响。BSH可能被排除在表皮细胞的细胞质之外，其CBE因子值较低（0.56±0.06），而可能选择性积聚在表皮细胞中的BPA具有非常高的CBE因子（3.74±0.7）。对于真皮反应，血管内皮细胞可能是靶细胞群体，BPA和BSH的CBE因子值相当，分别为0.73±0.42和0.86±0.08。
