Jernberg A, Edgren M R, Lewensohn R, Wiksell H, Brahme A
Division of Medical Radiation Physics, Karolinska Institutet, Stockholm, Sweden.
Int J Radiat Biol. 2001 Jan;77(1):127-35. doi: 10.1080/0955300010000791.
To investigate the cellular effects of 1.1 MHz high-intensity focused continuous wave (CW) ultrasound alone and in combination with X-rays.
V79 cells were exposed to ultrasound of different intensities for 30s (non-hyperthermic conditions). In the combined treatments, cells were exposed to ultrasound (63 W/cm2) either before or after 2 Gy X-irradiation. Cellular effects studied were clonogenic survival, DNA strand breaks (pulsed-field gel electrophoresis, DNA precipitation assay) and membrane integrity (morphological analysis).
With increasing ultrasound intensity, cell survival decreased in a dose-dependent manner as the induction of DNA strand breaks, the fraction of cells with lost membrane integrity and cell lysis increased. In the treatments with combined exposures, the regimen with X-rays before ultrasound had a nearly additive effect on cell kill, whereas the reverse regimen with ultrasound exposure before X-irradiation resulted in a synergistic effect (p<0.012).
High-intensity focused CW ultrasound induces an intensity-dependent reduction in clonogenic survival in V79 cells, which seems to depend on both DNA and membrane damage. Combined exposures of ultrasound and X-rays resulted in a synergistic reduction in cell survival when cells were exposed to ultrasound before X-rays but not for the reverse regimen. Thus, a larger fraction of the repairable sublethal cell damage induced by an initial ultrasound exposure was rendered non-repairable by a subsequent X-ray exposure than if the reverse treatment order was used.
研究1.1兆赫高强度聚焦连续波（CW）超声单独作用以及与X射线联合作用的细胞效应。
将V79细胞在非热条件下暴露于不同强度的超声30秒。在联合治疗中，细胞在2戈瑞X射线照射之前或之后暴露于超声（63瓦/平方厘米）。研究的细胞效应包括克隆形成存活率、DNA链断裂（脉冲场凝胶电泳、DNA沉淀测定）和膜完整性（形态学分析）。
随着超声强度增加，细胞存活率呈剂量依赖性下降，同时DNA链断裂诱导增加、膜完整性丧失的细胞比例及细胞裂解增加。在联合照射处理中，先进行X射线照射再进行超声照射的方案对细胞杀伤几乎具有相加效应，而先进行超声照射再进行X射线照射的相反方案则产生协同效应（p<0.012）。
高强度聚焦连续波超声可导致V79细胞克隆形成存活率呈强度依赖性降低，这似乎取决于DNA和膜损伤。超声与X射线联合照射时，先进行超声照射再进行X射线照射会导致细胞存活率协同降低，而相反方案则不然。因此，与采用相反治疗顺序相比，初始超声照射诱导的可修复亚致死性细胞损伤中有更大比例会因随后的X射线照射而变为不可修复。
