Schettino G, Folkard M, Prise K M, Vojnovic B, Held K D, Michael B D
Gray Cancer Institute, PO Box 100, Mount Vernon Hospital, Northwood, Middlesex, HA6 2JR, United Kingdom.
Radiat Res. 2003 Nov;160(5):505-11. doi: 10.1667/rr3060.
The Gray Cancer Institute ultrasoft X-ray microprobe was used to quantify the bystander response of individual V79 cells exposed to a focused carbon K-shell (278 eV) X-ray beam. The ultrasoft X-ray microprobe is designed to precisely assess the biological response of individual cells irradiated in vitro with a very fine beam of low-energy photons. Characteristic CK X rays are generated by a focused beam of 10 keV electrons striking a graphite target. Circular diffraction gratings (i.e. zone plates) are then employed to focus the X-ray beam into a spot with a radius of 0.25 microm at the sample position. Using this microbeam technology, the correlation between the irradiated cells and their nonirradiated neighbors can be examined critically. The survival response of V79 cells irradiated with a CK X-ray beam was measured in the 0-2-Gy dose range. The response when all cells were irradiated was compared to that obtained when only a single cell was exposed. The cell survival data exhibit a linear-quadratic response when all cells were targeted (with evidence for hypersensitivity at low doses). When only a single cell was targeted within the population, 10% cell killing was measured. In contrast to the binary bystander behavior reported by many other investigations, the effect detected was initially dependent on dose (<200 mGy) and then reached a plateau (>200 mGy). In the low-dose region (<200 mGy), the response after irradiation of a single cell was not significantly different from that when all cells were exposed to radiation. Damaged cells were distributed uniformly over the area of the dish scanned (approximately 25 mm2). However, critical analysis of the distance of the damaged, unirradiated cells from other damaged cells revealed the presence of clusters of damaged cells produced under bystander conditions.
格雷癌症研究所的超软X射线微探针被用于量化暴露于聚焦碳K壳层（278电子伏特）X射线束下的单个V79细胞的旁观者效应。该超软X射线微探针旨在精确评估体外被非常细的低能光子束照射的单个细胞的生物学反应。特征性CK X射线由一束10 keV电子撞击石墨靶产生。然后使用圆形衍射光栅（即波带片）将X射线束聚焦到样品位置处半径为0.25微米的光斑。利用这种微束技术，可以严格检查受照射细胞与其未受照射的相邻细胞之间的相关性。在0 - 2戈瑞剂量范围内测量了用CK X射线束照射的V79细胞的存活反应。将所有细胞都受到照射时的反应与仅单个细胞受到照射时获得的反应进行了比较。当所有细胞都作为靶点时，细胞存活数据呈现线性二次反应（在低剂量时有超敏反应的证据）。当群体中仅单个细胞作为靶点时，测得10%的细胞杀伤率。与许多其他研究所报道的二元旁观者行为不同，检测到的效应最初依赖于剂量（<200毫戈瑞），然后达到平台期（>200毫戈瑞）。在低剂量区域（<200毫戈瑞），单个细胞照射后的反应与所有细胞都接受辐射时的反应没有显著差异。受损细胞均匀分布在扫描的培养皿区域（约25平方毫米）。然而，对受损的未受照射细胞与其他受损细胞之间距离的严格分析揭示了在旁观者条件下产生的受损细胞簇的存在。
