Radiation research
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As the multi-systemic components of COVID-19 emerge, parallel etiologies can be drawn between SARS-CoV-2 infection and radiation injuries. While some SARS-CoV-2-infected individuals present as asymptomatic, others exhibit mild symptoms that may include fever, cough, chills, and unusual symptoms like loss of taste and smell and reddening in the extremities (e.g., "COVID toes," suggestive of microvessel damage). Still others alarm healthcare providers with extreme and rapid onset of high-risk indicators of mortality that include acute respiratory distress syndrome (ARDS), multi-organ hypercoagulation, hypoxia and cardiovascular damage. ⋯ The potentially dramatic human impact of ARS has guided the science that has identified many biomarkers of radiation exposure, established medical management strategies for ARS, and led to the development of medical countermeasures for use in the event of a radiation public health emergency. These efforts can now be leveraged to help elucidate mechanisms of action of COVID-19 injuries. Furthermore, this intersection between COVID-19 and ARS may point to approaches that could accelerate the discovery of treatments for both.
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Combined radiation-burn injury can occur in people exposed to nuclear explosions, nuclear accidents or radiological terrorist attacks. Using different combined radiation-burn injury animal models, the pathological mechanisms underlying combined radiation-burn injury and effective medical countermeasures have been explored for several years in China, mainly at our institute. Targeting key features of combined radiation-burn injury, several countermeasures have been developed. ⋯ Transfusion of irradiated (20 Gy) or stored (4°C, 7 days) blood improves the survival of allo-skin grafting and allo-bone marrow cells. In conclusion, as our understanding of the mechanisms of combined radiation-burn injury has progressed, new countermeasures have been developed for its treatment. Because of the complexity of its pathology and the difficulty in clinical management, further efforts are needed to improve the treatment of this kind of injury.
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The concept of intrinsic radiosensitivity is now strongly associated with the linear-quadratic (LQ) model which is currently the best and the most reliable method to fit the first three decades of a survival curve for both human fibroblast and human tumor cell lines. This approach has led to the major conclusions that it is the initial part, and not the distal part, of the survival curve which truly characterizes intrinsic cellular radiosensitivity and there is a correlation between the parameters describing mainly the initial part of the survival curve (alpha, SF2, D) and the clinical radioresponsiveness. More accurate analysis with flow cytometry or a dynamic microscopic image processing scanner (DMIPS) has allowed further study of the survival curve which has shown two sorts of substructure. ⋯ However, it may be important to bear in mind the possible extra effect of low doses outside the target volume if regions in the vicinity are subsequently retreated. Concerning clinical radiation-induced carcinogenesis, three studies described a higher relative risk associated with small doses per fraction or very low dose rate. The results and the interpretation of these studies are discussed.