Project description:Background: The effects of dose-rate and its implications on radiation biodosimetry methods are not well studied in the context of large-scale radiological scenarios. There are significant health risks to individuals exposed to an acute dose in such an event, but the most realistic scenario would be a combination of exposure to both high and low dose-rates, from both external and internal radioactivity. It is important therefore, to understand the biological response to prolonged exposure; and further, discover biomarkers that can be used to estimate the extent of damage from low-dose rate exposure and propose appropriate clinical treatment. Methods: We irradiated human whole blood ex vivo to three doses, 0.56 Gy, 2.25 Gy and 4.45 Gy, using two dose rates: 1.1Gy/min and 3.1mGy/min. After 24 hours, we isolated RNA from blood cells and hybridized these to Agilent Whole Human genome microarrays. We validated the microarray results using qRT-PCR. Results: Microarray results showed that there were 454 significantly differentially expressed genes after prolonged exposure to all doses. After acute exposure, 598 genes were differentially expressed to all doses combined. Gene ontology terms enriched in both sets of genes were related to immune processes and B cell mediated immunity. Genes responding to acute exposure was also enriched in functions related to natural killer cell activation and cell-to-cell signaling. As expected, p53 pathway was found to be significantly enriched at all doses and by both dose-rates of radiation. Prediction algorithms were able to distinguish between low dose-rate and acute exposures, on the basis of a group of genes. These maybe candidates for preliminary testing as markers for differences in gene expression based on dose-rate. Radiation induced gene expression was measured in ex vivo irradiated human blood, at the 24hr time point after irradiation. Doses (0.56 Gy, 2.2 Gy and 4.45 Gy) were delivered by two dose rates, acute dose rate of 1Gy/min and low dose rate of 3.1 mGy/min.
Project description:Radiation biodosimetry can play a critical role in the response to a large-scale radiologic emergency, and gene expression profiles have shown promise for providing biodosimetric information. This study was designed to test if gene expression could be used to distinguish between doses received from acute exposures and more protracted exposures, such as those that would result from fallout. Mice were exposed to whole body X-rays at low dose rate (LDR, 3.09 mGy/min) for 6, 12, or 24 hours (1.1, 2.2, or 4.4 Gy), or to equivalent doses delivered at high dose rate (HDR, 1.03 Gy/min). Global gene expression was measured in their blood 24 h after the start of exposure, and genes with the potential to classify samples by radiation dose and dose rate were identified. Data consist of 48 samples, representing 6 independent samples each from 3 doses delivered as either acute or low dose rate x-rays, plus 12 controls representing both acute and low dose rate sham treatments.
Project description:Background: The effects of dose-rate and its implications on radiation biodosimetry methods are not well studied in the context of large-scale radiological scenarios. There are significant health risks to individuals exposed to an acute dose in such an event, but the most realistic scenario would be a combination of exposure to both high and low dose-rates, from both external and internal radioactivity. It is important therefore, to understand the biological response to prolonged exposure; and further, discover biomarkers that can be used to estimate the extent of damage from low-dose rate exposure and propose appropriate clinical treatment. Methods: We irradiated human whole blood ex vivo to three doses, 0.56 Gy, 2.25 Gy and 4.45 Gy, using two dose rates: 1.1Gy/min and 3.1mGy/min. After 24 hours, we isolated RNA from blood cells and hybridized these to Agilent Whole Human genome microarrays. We validated the microarray results using qRT-PCR. Results: Microarray results showed that there were 454 significantly differentially expressed genes after prolonged exposure to all doses. After acute exposure, 598 genes were differentially expressed to all doses combined. Gene ontology terms enriched in both sets of genes were related to immune processes and B cell mediated immunity. Genes responding to acute exposure was also enriched in functions related to natural killer cell activation and cell-to-cell signaling. As expected, p53 pathway was found to be significantly enriched at all doses and by both dose-rates of radiation. Prediction algorithms were able to distinguish between low dose-rate and acute exposures, on the basis of a group of genes. These maybe candidates for preliminary testing as markers for differences in gene expression based on dose-rate.
Project description:Accidents with ionizing radiation (IR) often involve acute high dose exposures that can lead to acute radiation syndrome and late effects. IR can induce genomic lesions, cell death or carcinogenesis. Here, we investigated acute IR-induced cellular genomic signatures at the genome wide level. After exposing the adenocarcinoma cell line A549 to an acute 6 Gy 240 kV X-Ray dose, four surviving clonogenic cells were recovered by minimal dilution and further expanded and analyzed by cytogenetics, chromosome painting and tiling-path array CGH, with the non-irradiated clone0 serving as control. It was found that acute X-ray exposure induced changes in modal chromosome number and specific translocations in the four irradiation surviving clones. Furthermore, clone4 displayed an increased radiosensitivity at D > 5 Gy. Array CGH disclosed unique and recurrent genomic changes, predominantly gains, and disclosed fragile sites FRA3B and FRA16D as preferential regions of genomic alterations in all irradiated clones, which likely relates to irradiation-induced genomic stress. Gene expression analysis revealed a specific profile of 364 genes in clone4, of which p53 pathway genes may contribute to its increased radiosensitivity. IR-induced genomic changes AND fragile site expression highlight the capacity of a single acute radiation exposure to resculpture the genome of tumor cells by inflicting genomic stress. Gene expression in A549 cell line was analysed after exposure to 6Gy X-rays at a dose rate of 1Gy/min.
Project description:The biomedical consequences of space radiation pose a significant concern for astronauts engaged in deep space. However, the effects of long-term low dose-rate exposures in space environments remain elusive. In this study, we simulated the space radiation environment by exposing human bronchial epithelial cells to low dose-rate (0.0067 Gy/day) α-particles, and continuously irradiated them multiple times to achieve cumulative total doses of 0.2 Gy, 0.4 Gy, and 0.5 Gy, respectively. At the same time, the cells were irradiated with the same total dose in a single exposure to investigate the potential of low dose-rate alpha particles to induce malignant transformation of human bronchial epithelial cells. A comprehensive suite of assays was employed to assess tumorigenic potential, including tumor formation in NOD/SCID mice, immunohistochemistry, CCK-8 proliferation assay, invasion assay, and the evaluation of multicellular spheroid formation during subsequent passages post-irradiation. Moreover, we dissected differential malignant mechanisms in tumor evolution ecosystem induced by the two distinct irradiation modes from systems biology views based on scRNA-seq technology. Our results showed that exposure to α-particles, whether through a single acute exposure or long-term low dose-rate exposures, induced the occurrence and development of tumors. Long-term low dose-rate exposures to α-particles increase the malignancy of induced tumors, but not the risk of carcinogenesis, compared to a single acute exposure with the same total dose. In addition, through scRNA-seq, we found that long-term low dose-rate exposures triggered more copy number variation (CNV) and epithelial-mesenchymal transition (EMT) events, and the activation of DNA damage repair pathways occurred significantly later than with a single acute exposure and involved more specific changes in cellular communication dynamics. In conclusion, our findings provide emerging yet convincing evidence that not only sheds light on why cells exposed to long-term low dose-rate exposures exhibit heightened malignancy, but also offers valuable insights into the genetic determinants driving tumor evolution and heterogeneity.
Project description:Low-LET radiation can cause cardiovascular dysfunctions at high-dose rates. For example, photons used in thoracic radiotherapy are known to cause acute cardiac tissue damage with elevated serum cardiac Troponin I level and long-term cardiac complications when delivered as fractionated exposures at high-dose rates. However, the effects of continuous low-dose rate radiation exposure on the heart, which simulate the space radiation environment, have not been well-studied. In this study, we aim to model low-LET space radiation-induced cardiovascular dysfunction using human induced pluripotent stem cell (iPSC)-derived engineered heart tissues (EHTs) exposed to protracted γ-ray irradiation. The investigation of pathophysiological changes in this model may provide insights and guide the development of countermeasures. As a proof-of-principle for the application of this model in drug development, we also tested the protective effect of a mitochondrial-specific antioxidant, MitoTempo, on irradiated EHTs.
Project description:Radiation biodosimetry can play a critical role in the response to a large-scale radiologic emergency, and gene expression profiles have shown promise for providing biodosimetric information. This study was designed to test if gene expression could be used to distinguish between doses received from acute exposures and more protracted exposures, such as those that would result from fallout. Mice were exposed to whole body X-rays at low dose rate (LDR, 3.09 mGy/min) for 6, 12, or 24 hours (1.1, 2.2, or 4.4 Gy), or to equivalent doses delivered at high dose rate (HDR, 1.03 Gy/min). Global gene expression was measured in their blood 24 h after the start of exposure, and genes with the potential to classify samples by radiation dose and dose rate were identified.
Project description:Gene expressions of mice hepatocellular adenoma, which correlated with low-dose-rate gamma ray radiation dependent inflammatory response