Sugimoto M, Takahashi S, Kotoura Y, Shibamoto Y, Takahashi M, Abe M, Ishizaki K, Yamamuro T
Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University, Japan.
Clin Orthop Relat Res. 1993 Dec(297):247-52.
The effects of high-dose irradiation on the metabolism of osteocytes were examined with respect to RNA synthesis. A single 50-Gy dose of high-energy electron beam was given to the proximal tibia of rabbits. RNA synthesis by osteocytes was quantified by counting the silver grains on autoradiographs of cultured bone fragments, using 3H-cytidine as a tracer. At four, 12, and 52 weeks after irradiation, RNA synthesis by the irradiated osteocytes was 72, 62, and 79%, respectively, of that by nonirradiated osteocytes. The proportion of labeled osteocytes, conversely, was not reduced at four and 12 weeks, but was significantly reduced at 52 weeks after irradiation. The reduction in the RNA synthesis of osteocytes occurs fairly quickly, whereas reduction in the number of viable osteocytes occurs slowly as a delayed sequela. Histologic examination showed that the partial recovery of RNA synthesis observed at 52 weeks was attributable to the appearance of a fraction of new osteocytes, i.e., subendosteal apposition of new bone to the original, degrading cortex. These observations demonstrate the process of recovery from radiation damage.
就RNA合成而言，研究了高剂量辐射对骨细胞代谢的影响。给兔胫骨近端单次给予50 Gy的高能电子束剂量。以3H-胞苷为示踪剂，通过对培养的骨碎片放射自显影片上的银颗粒进行计数，对骨细胞的RNA合成进行定量。照射后4周、12周和52周，照射骨细胞的RNA合成分别为未照射骨细胞的72%、62%和79%。相反，标记骨细胞的比例在照射后4周和12周没有降低，但在52周时显著降低。骨细胞RNA合成的减少相当迅速，而存活骨细胞数量的减少则作为延迟后遗症缓慢发生。组织学检查表明，52周时观察到的RNA合成部分恢复归因于一部分新骨细胞的出现，即新骨在原始退化皮质的骨内膜下附着。这些观察结果证明了从辐射损伤中恢复的过程。
