Sakurai H, Mitsuhasi N, Takahashi T, Hashida I, Niibe H
Department of Radiology, Gunma University, School of Medicine, Showa-machi, Maebashi, Gunma, Japan.
Int J Hyperthermia. 1996 May-Jun;12(3):355-66. doi: 10.3109/02656739609022524.
We have pursued an in vitro investigation using a rodent cell line to characterize the interaction of simultaneous low dose-rate irradiation (LDRI) and hyperthermia and to determine the role of LDRI in the development of thermotolerance in a fractionated hyperthermia schedule. Yoshida sarcoma cells growing in vitro were used in this study. Cell survivals were estimated by the Courteney soft agar clonogenic assay. A treatment device for LDRI treatment, which held eight 137Cs sources and agar plus containing the cells, gave an irradiation dose of 51.8 cGy/h to the cells. In the experiment of simultaneous LDRI and hyperthermia, the LDRI cytotoxicities were enhanced by hyperthermia over a non-lethal temperature range. High synergistic effects were observed in a lower temperature range (40, 41 and 41.5 degrees C) in contrast to higher temperature (42, 43 and 44 degrees C). In the experiment of alternate LDRI and hyperthermia, thermotolerance induced by initial heating was well developed during the LDR exposure but less expressed in comparison with the cells which had no LDRI exposure. The treatment of LDRI for 8 h may have affected the thermotolerance development in our experimental condition.
我们采用啮齿动物细胞系进行了一项体外研究，以表征低剂量率照射（LDRI）与热疗同时作用时的相互作用，并确定LDRI在分次热疗方案中热耐受形成过程中的作用。本研究使用体外培养的吉田肉瘤细胞。通过考特尼软琼脂克隆形成试验评估细胞存活率。一种用于LDRI治疗的装置，其中放置了8个137Cs源以及含有细胞的琼脂加样，给予细胞的照射剂量为51.8 cGy/h。在LDRI与热疗同时进行的实验中，在非致死温度范围内，热疗增强了LDRI的细胞毒性。与较高温度（42、43和44摄氏度）相比，在较低温度范围（40、41和41.5摄氏度）观察到了高协同效应。在LDRI与热疗交替进行的实验中，初始加热诱导的热耐受在LDR照射期间得到良好发展，但与未接受LDRI照射的细胞相比，表达较少。在我们的实验条件下，8小时的LDRI治疗可能影响了热耐受的形成。
