van Loon A A, Raadsheer F C, Timmerman A J, Haanen C, Wessels J, van der Schans G P, Lohmans P H, Baan R A
TNO Medical Biological Laboratory, Rijswijk, The Netherlands.
Int J Radiat Biol. 1992 Jul;62(1):33-43. doi: 10.1080/09553009214551801.
Chemotherapy combined with total-body irradiation (TBI), a conditioning regimen for bone-marrow transplantation (BMT), causes lesions in the cellular DNA of the patients treated. To understand possible consequences of the DNA damage induced during such treatment, information is required about the nature of the damage, the level of induction and its persistence, and about the importance of the various lesions for cell-lethality and/or mutation induction. Recently, we developed a sensitive immunochemical method to quantify single-strand breaks (SSB) in the DNA of mammalian cells. In addition, a modification of the so-called alkaline elution technique was introduced which allows quantification of SSB together with base damage (SSB+BD). These methods have now been applied successfully to study the in vivo induction and repair of DNA damage in WBC of leukaemia patients who prior to BMT were treated with cyclophosphamide (CY) and received TBI. SSB and SSB+BD were determined after two treatments with CY (60 mg kg-1) followed by TBI (4.5-8.6Gy). The CY treatments gave rise to rather persistent SSB. In addition to these, radiation-induced SSB and SSB+BD could be detected shortly after TBI. However, 105 min after TBI, these SSB could be observed no longer, as a result of rapid repair.
化疗联合全身照射（TBI）作为骨髓移植（BMT）的预处理方案，会导致接受治疗的患者细胞DNA发生损伤。为了解这种治疗过程中诱导产生的DNA损伤可能造成的后果，需要掌握有关损伤性质、诱导水平及其持续性的信息，以及各种损伤对于细胞致死率和/或突变诱导的重要性。最近，我们开发了一种灵敏的免疫化学方法来定量哺乳动物细胞DNA中的单链断裂（SSB）。此外，还引入了所谓碱性洗脱技术的一种改良方法，该方法可对SSB和碱基损伤（SSB+BD）进行定量。这些方法现已成功应用于研究白血病患者白细胞中DNA损伤的体内诱导和修复情况，这些患者在BMT前接受了环磷酰胺（CY）治疗并接受了TBI。在用CY（60mg/kg）进行两次治疗后再进行TBI（4.5 - 8.6Gy），然后测定SSB和SSB+BD。CY治疗导致相当持久的SSB。除此之外，在TBI后不久可检测到辐射诱导的SSB和SSB+BD。然而，由于快速修复，在TBI后105分钟，这些SSB就不再能被观察到了。
