Radiation databases and archives - examples and comparisons

Human-mouse comparison of the multistage nature of radiation carcinogenesis in a mathematical model

Mouse models are vital for assessing risk from environmental carcinogens, including ionizing radiation, yet the interspecies difference in the dose response precludes direct application of experimental evidence to humans. Herein, we take a mathematical approach to delineate the mechanism underlying the human-mouse difference in radiation-related cancer risk. We used a multistage carcinogenesis model assuming a mutational action of radiation to analyze previous data on cancer mortality in the Japanese atomic bomb survivors and in lifespan mouse experiments. Theoretically, the model predicted that exposure will chronologically shift the age-related increase in cancer risk forward by a period corresponding to the time in which the spontaneous mutational process generates the same mutational burden as that the exposure generates. This model appropriately fitted both human and mouse data and suggested a linear dose response for the time shift. The effect per dose decreased with increasing age at exposure similarly between humans and mice on a per-lifespan basis (0.72- and 0.71-fold, respectively, for every tenth lifetime). The time shift per dose was larger by two orders of magnitude in humans (7.8 and 0.046 years per Gy for humans and mice, respectively, when exposed at ~35% of their lifetime). The difference was mostly explained by the two orders of magnitude difference in spontaneous somatic mutation rates between the species plus the species-independent radiation-induced mutation rate. Thus, the findings delineate the mechanism underlying the interspecies difference in radiation-associated cancer mortality and may lead to the use of experimental evidence for risk prediction in humans.

Artificial intelligence in biology and medicine, and radioprotection research: perspectives from Jerusalem

While AI is widely used in biomedical research and medical practice, its use is constrained to few specific practical areas, e.g., radiomics. Participants of the workshop on "Artificial Intelligence in Biology and Medicine" (Jerusalem, Feb 14-15, 2023), both researchers and practitioners, aimed to build a holistic picture by exploring AI advancements, challenges and perspectives, as well as to suggest new fields for AI applications. Presentations showcased the potential of large language models (LLMs) in generating molecular structures, predicting protein-ligand interactions, and promoting democratization of AI development. Ethical concerns in medical decision making were also addressed. In biological applications, AI integration of multi-omics and clinical data elucidated the health relevant effects of low doses of ionizing radiation. Bayesian latent modeling identified statistical associations between unobserved variables. Medical applications highlighted liquid biopsy methods for non-invasive diagnostics, routine laboratory tests to identify overlooked illnesses, and AI's role in oral and maxillofacial imaging. Explainable AI and diverse image processing tools improved diagnostics, while text classification detected anorexic behavior in blog posts. The workshop fostered knowledge sharing, discussions, and emphasized the need for further AI development in radioprotection research in support of emerging public health issues. The organizers plan to continue the initiative as an annual event, promoting collaboration and addressing issues and perspectives in AI applications with a focus on low-dose radioprotection research. Researchers involved in radioprotection research and experts in relevant public policy domains are invited to explore the utility of AI in low-dose radiation research at the next workshop.

Proof of principle study: synchrotron X-ray fluorescence microscopy for identification of previously radioactive microparticles and elemental mapping of FFPE tissues

Biobanks containing formalin-fixed, paraffin-embedded (FFPE) tissues from animals and human atomic-bomb survivors exposed to radioactive particulates remain a vital resource for understanding the molecular effects of radiation exposure. These samples are often decades old and prepared using harsh fixation processes which limit sample imaging options. Optical imaging of hematoxylin and eosin (H&E) stained tissues may be the only feasible processing option, however, H&E images provide no information about radioactive microparticles or radioactive history. Synchrotron X-ray fluorescence microscopy (XFM) is a robust, non-destructive, semi-quantitative technique for elemental mapping and identifying candidate chemical element biomarkers in FFPE tissues. Still, XFM has never been used to uncover distribution of formerly radioactive micro-particulates in FFPE canine specimens collected more than 30 years ago. In this work, we demonstrate the first use of low-, medium-, and high-resolution XFM to generate 2D elemental maps of ~ 35-year-old, canine FFPE lung and lymph node specimens stored in the Northwestern University Radiobiology Archive documenting distribution of formerly radioactive micro-particulates. Additionally, we use XFM to identify individual microparticles and detect daughter products of radioactive decay. The results of this proof-of-principle study support the use of XFM to map chemical element composition in historic FFPE specimens and conduct radioactive micro-particulate forensics.

Identifying Genomic Signatures of Positive Selection to Predict Protective Genomic Loci in the Cohort of Lithuanian Clean-Up Workers of the Chornobyl Nuclear Disaster

Some people resist or recover from health challenges better than others. We studied Lithuanian clean-up workers of the Chornobyl nuclear disaster (LCWC) who worked in the harshest conditions and, despite high ionising radiation doses as well as other factors, continue ageing relatively healthily. Thus, we hypothesised that there might be individual features encoded by the genome which act protectively for better adaptiveness and health that depend on unique positive selection signatures. Whole-genome sequencing was performed for 40 LCWC and a control group composed of 25 men from the general Lithuanian population (LTU). Selective sweep analysis was performed to identify genomic regions which may be under recent positive selection and determine better adaptiveness. Twenty-two autosomal loci with the highest positive selection signature values were identified. Most important, unique loci under positive selection have been identified in the genomes of the LCWC, which may influence the survival and adaptive qualities to extreme conditions, and the disaster itself. Characterising these loci provide a better understanding of the interaction between ongoing microevolutionary processes, multifactorial traits, and diseases. Studying unique groups of disease-resistant individuals could help create new insights for better, more individualised, disease diagnostics and prevention strategies.

ICRP PUBLICATION 153 Approved by the Commission in September 2022

Veterinary use of radiation in the diagnosis, management, and treatment of disease has expanded and diversified, as have the corresponding radiological protection concerns. Radiological exposure of personnel involved in veterinary procedures and, where applicable, members of the public providing assistance (e.g. owners or handlers) has always been included within the system of radiological protection. Veterinary practice is now addressed explicitly as the modern complexities associated with this practice warrant dedicated consideration, and there is a need to clarify and strengthen the application of radiological protection principles in this area. The Commission recommends that the system of radiological protection should be applied in veterinary practice principally for the protection of humans, but with explicit attention to the protection of exposed animals. Additionally, consideration should be given to the risk of potential contamination of the environment associated with applications of nuclear medicine in veterinary practice. This publication focuses primarily on justification and optimisation in veterinary practice, and sets the scene for more detailed guidance to follow in future Recommendations. It is intended for a wide-ranging audience, including radiological protection professionals, veterinary staff, students, education and training providers, and members of the public, as an introduction to radiological protection in veterinary practice.© 2022 ICRP. Published by SAGE.

COHERE - strengthening cooperation within the Canadian government on radiation research

PURPOSE

Canadian Organization on Health Effects from Radiation Exposure (COHERE) is a government initiative to better understand biological and human health risks from ionizing radiation exposures relevant to occupational and environmental settings (<100 mGy, <6 mGy/h). It is currently a partnership between two federal agencies, Health Canada (HC) and the Canadian Nuclear Safety Commission (CNSC). COHERE's vision is to contribute knowledge to reduce scientific uncertainties from low dose and dose-rate exposures. COHERE will advance our understanding by bridging the knowledge gap between human health risks and linkages to molecular- and cellular-level responses to radiation. Research focuses on identifying sensitive, early, and key molecular events of relevance to risk assessment.

CONCLUSIONS

The initiative will address questions of relevance to better apprize Canadians, including radiation workers and members of the public and Indigenous peoples, on health risks from low dose radiation exposure and inform radiation protection frameworks at a national and international level. Furthermore, it will support global efforts to conduct collaborative undertakings and better coordinate research. Here, we describe a historical overview of the research conducted, the strategic research agenda that outlines the scientific framework, stakeholders, opportunities to harmonize internationally, and how research outcomes will better inform communication of risk to Canadians.

Analyses of cancer incidence and other morbidities in neutron irradiated B6CF1 mice

The Department of Energy conduced ten large-scale neutron irradiation experiments at Argonne National Laboratory between 1972 and 1989. Using a new approach to utilize experimental controls to determine whether a cross comparison between experiments was appropriate, we amalgamated data on neutron exposures to discover that fractionation significantly improved overall survival. A more detailed investigation showed that fractionation only had a significant impact on the death hazard for animals that died from solid tumors, but did not significantly impact any other causes of death. Additionally, we compared the effects of sex, age first irradiated, and radiation fractionation on neutron irradiated mice versus cobalt 60 gamma irradiated mice and found that solid tumors were the most common cause of death in neutron irradiated mice, while lymphomas were the dominant cause of death in gamma irradiated mice. Most animals in this study were irradiated before 150 days of age but a subset of mice was first exposed to gamma or neutron irradiation over 500 days of age. Advanced age played a significant role in decreasing the death hazard for neutron irradiated mice, but not for gamma irradiated mice. Mice that were 500 days old before their first exposures to neutrons began dying later than both sham irradiated or gamma irradiated mice.

Analyses of cancer incidence and other morbidities in gamma irradiated B6CF1 mice

With increasing medical radiation exposures, it is important to understand how different modes of delivery of ionizing radiation as well as total doses of exposure impact health outcomes. Our lab studied the risks associated with ionizing radiation by analyzing the Northwestern University Radiation Archive for animals (NURA). NURA contains detailed data from a series of 10 individual neutron and gamma irradiation experiments conducted on over 50,000 mice. Rigorous statistical testing on control mice from all Janus experiments enabled us to select studies that could be compared to one another and uncover unexpected differences among the controls as well as experimental animals. For controls, mice sham irradiated with 300 fractions died significantly earlier than those with fewer sham fractions and were excluded from the pooled dataset. Using the integrated dataset of gamma irradiated and control mice, we found that fractionation significantly decreased the death hazard for animals dying of lymphomas, tumors, non-tumors, and unknown causes. Gender differences in frequencies of causes of death were identified irrespective of irradiation and dose fractionation, with female mice being at a greater risk for all causes of death, except for lung tumors. Irradiated and control male mice were at a significantly greater risk for lung tumors, the opposite from observations noted in humans. Additionally, we discovered that lymphoma deaths can occur quickly after exposures to high doses of gamma rays. This study systematically cross-compared outcomes of different modes of fractionation evaluated across different Janus experiments and across a wide span of total doses. It demonstrates that protraction modulated survival and disease status differently based on the total dose, cause of death, and sex of an animal. This novel method for analyzing the Janus datasets will lead to insightful new mechanistic hypotheses and research in the fields of radiation biology and protection.

Research on the Radiotoxicology of Plutonium Using Animals: Consideration of the 3Rs-Replace, Reduce, Refine

To characterize the health effects of incorporated plutonium, many experiments have been conducted using different animal models. These range from (1) applied (tissue uptake/retention determination, decorporation therapy efficacy), (2) fundamental (gene expression, cancer induction), and (3) dosimetry models. In recent years, the use of animals for scientific purposes has become a public concern. The application of the 3Rs - Replace (use of alternative methods or animals not considered capable of experiencing pain, suffering, and distress), Reduce (reduction in animal numbers), and Refine (better animal welfare and minimization of suffering, pain and distress) - has increased to address ethical concerns and legislative requirements. The introduction of novel non-animal technologies is also an important factor as complementary options to animal experimentation. In radiotoxicology research, it seems there is a natural tendency to Replace given the possibility of data reuse obtained from contamination cases in man and animal studies. The creation of "registries" and "repositories" for nuclear industry workers (civil and military) is now a rich legacy for radiotoxicological measurements. Similarly, Reduction in animal numbers can be achieved by good experimental planning with prior statistical analyses of animal numbers required to obtain robust data. Multiple measurements in the same animal over time (external body counting, excreta collection) with appropriate detection instruments also allow Reduction. In terms of Refinement, this has become "de rigueur" and a necessity given the societal and legal concerns for animal welfare. For research in radiotoxicology, particularly long-term studies, better housing conditions within the constraints of radiation protection issues for research workers are an important concern. These are all pertinent considerations for the 3Rs remit and future research in radiotoxicology.

Establishing the Japan-Store house of animal radiobiology experiments (J-SHARE), a large-scale necropsy and histopathology archive providing international access to important radiobiology data

Purpose: Projects evaluating the effects of radiation, within the National Institutes of Quantum and Radiological Science and Technology (QST), National Institute of Radiological Sciences (NIRS), have focused on risk analyses for life shortening and cancer prevalence using laboratory animals. Genetic and epigenetic alterations in radiation-induced tumors have been also analyzed with the aim of better understanding mechanisms of radiation carcinogenesis. As well as the economic and practical limitations of repeating such large-scale experiments, ethical considerations make it vital that we store and share the pathological data and samples of the animal experiments for future use. We are now constructing such an archive called the Japan-Storehouse of Animal Radiobiology Experiments (J-SHARE). Methods: J-SHARE records include information such as detailed experimental protocols, necropsy records and photographs of organs at necropsy. For each animal organs and tumor tissues are dissected, and parts are stored as frozen samples at -80 °C. Samples fixed with formalin are also embedded in paraffin blocks for histopathological analyses. Digital copies of stained tissues are being systematically saved using a virtual slide system linked to original records by barcodes. Embedded and frozen tissues are available for molecular analysis. Conclusion: Similar archive systems for radiation biology have also been under construction in the USA and Europe, the Northwestern University Radiation Archive (NURA), and STORE at the BfS, respectively. The J-SHARE will be linked with the sister-archives and made available for collaborative research to institutions and universities all over the world.