Calcified Tissue International ( IF 4.2 ) Pub Date : 2021-01-30 , DOI: 10.1007/s00223-021-00806-7 Patricia K Thomas 1 , Lindsay K Sullivan 2 , Gary H Dickinson 3 , Catherine M Davis 4, 5 , Anthony G Lau 1
Ionizing radiation, from both space and radiation therapy, is known to affect bone health. While there have been studies investigating changes in bone density and microstructure from radiation exposure, the effects of radiation on material properties are unknown. The current study addresses this gap by assessing bone material property changes in rats exposed to helium-4 radiation through spherical micro-indentation. Rats were exposed to a single dose of 0, 5, and 25 cGy whole body helium-4 radiation. Animals were euthanized at 7, 30, 90, or 180-days after exposure. Spherical micro-indentation was performed on axial cross sections of the femur cortical bone to determine instantaneous and relaxed shear moduli. At 90-days after exposure, the 25 cGy exposure caused a significant decline in shear modulus compared to control and 5 cGy groups. The instantaneous modulus decreased 33% and the relaxed modulus decreased 32% as compared to the sham group. This decline was followed by a recovery of both moduli, which was observed by 180-days after exposure; at 180 days, the moduli were no longer statistically different from those at 7 or 30 days. The observed decrease at 90 days, followed by recovery to baseline levels, can be attributed to the biological mechanisms involved in bone formation that were affected by radiation, bone turnover, and systemic changes in hormones due to radiation exposure. Continued assessment of the mechanisms that drive such a response in material properties may enable identification of pathways for therapeutic countermeasures against radiation exposure.
中文翻译:
氦离子辐射对骨材料特性的影响
已知来自太空和放射治疗的电离辐射会影响骨骼健康。虽然已经有研究调查辐射暴露引起的骨密度和微观结构的变化,但辐射对材料特性的影响尚不清楚。目前的研究通过球形微压痕评估暴露于氦 4 辐射的大鼠的骨材料特性变化来解决这一差距。大鼠暴露于单剂量的 0、5 和 25 cGy 全身氦 4 辐射。在暴露后 7、30、90 或 180 天对动物实施安乐死。在股骨皮质骨的轴向截面上进行球形微压痕以确定瞬时和松弛剪切模量。在暴露后 90 天,与对照组和 5 cGy 组相比,25 cGy 暴露导致剪切模量显着下降。与假手术组相比,瞬时模量降低了 33%,松弛模量降低了 32%。在这种下降之后,两个模量都恢复了,这是在暴露后 180 天观察到的;在 180 天时,模量与 7 天或 30 天时的模量不再有统计学差异。观察到的第 90 天下降,随后恢复到基线水平,可归因于骨形成所涉及的生物机制,这些机制受辐射、骨转换和辐射暴露引起的全身激素变化的影响。对材料特性中驱动这种反应的机制的持续评估可能有助于确定针对辐射暴露的治疗对策的途径。在这种下降之后,两个模量都恢复了,这是在暴露后 180 天观察到的;在 180 天时,模量与 7 天或 30 天时的模量不再有统计学差异。在第 90 天观察到的减少,随后恢复到基线水平,可归因于骨形成所涉及的生物学机制,这些机制受辐射、骨转换和辐射暴露引起的全身激素变化的影响。对材料特性中驱动这种反应的机制的持续评估可能有助于确定针对辐射暴露的治疗对策的途径。在这种下降之后,两个模量都恢复了,这是在暴露后 180 天观察到的;在 180 天时,模量与 7 天或 30 天时的模量不再有统计学差异。在第 90 天观察到的减少,随后恢复到基线水平,可归因于骨形成所涉及的生物学机制,这些机制受辐射、骨转换和辐射暴露引起的全身激素变化的影响。对材料特性中驱动这种反应的机制的持续评估可能有助于确定针对辐射暴露的治疗对策的途径。随后恢复到基线水平,这可归因于骨形成所涉及的生物机制,这些机制受辐射、骨转换和辐射暴露引起的全身激素变化的影响。对材料特性中驱动这种反应的机制的持续评估可能有助于确定针对辐射暴露的治疗对策的途径。随后恢复到基线水平,这可归因于骨形成所涉及的生物机制,这些机制受辐射、骨转换和辐射暴露引起的全身激素变化的影响。对材料特性中驱动这种反应的机制的持续评估可能有助于确定针对辐射暴露的治疗对策的途径。