Project description:An important component of ionizing radiation (IR) exposure after a radiological incident may include low-dose rate (LDR) exposures either externally or internally, such as from 137Cs deposition. In this study, a novel irradiation system, VAriable Dose-rate External 137Cs irradiatoR (VADER), was used to expose male and female mice to a variable LDR irradiation over a 30 d time span to simulate fall-out-type exposures in addition to biofluid collection from a reference dose rate (0.8 Gy/min). Radiation markers were identified by untargeted metabolomics and random forests. Mice exposed to LDR exposures were successfully identified from control groups based on their urine and serum metabolite profiles. In addition to metabolites commonly perturbed after IR exposure, we identified and validated a novel metabolite (hexosamine-valine-isoleucine-OH) that increased up to 150-fold after LDR and 80-fold after conventional exposures in urine. A multiplex panel consisting of hexosamine-valine-isoleucine-OH with other urinary metabolites (N6,N6,N6-trimethyllysine, carnitine, 1-methylnicotinamide, and α-ketoglutaric acid) achieved robust classification performance using receiver operating characteristic curve analysis, irrespective of the dose rate or sex. These results show that in terms of biodosimetry, dysregulated energy metabolism is associated with IR exposure for both LDR and conventional IR exposures. These mass spectrometry data have been deposited to the NIH data repository via Metabolomics Workbench with study IDs ST001790, ST001791, ST001792, ST001793, and ST001806.
Project description:High-throughput biodosimetry methods to determine exposure to ionizing radiation (IR) that can also be easily scaled to multiple testing sites in emergency situations are needed in the event of malicious attacks or nuclear accidents that may involve a substantial number of civilians. In the event of an improvised nuclear device (IND), a complex IR exposure will have a very high-dose rate (VHDR) component from an initial blast. We have previously addressed low-dose rate (LDR, ≤1 Gy/day) exposures from internal emitters on biofluid small molecule signatures, but further research on the VHDR component of the initial blast is required. Here, we exposed 8- to 10-week-old male C57BL/6 mice to an acute dose of 3 Gy using a reference dose rate of 0.7 Gy/min or a VHDR of 7 Gy/s, collected urine and serum at 1 and 7 d, then compared the metabolite signatures using either untargeted (urine) or targeted (serum) approaches with liquid chromatography mass spectrometry platforms. A Random Forest classification approach showed strikingly similar changes in urinary signatures at 1 d post-irradiation with VHDR samples grouping closer to control samples at 7 d. Identical metabolite panels (carnitine, trigonelline, xanthurenic acid, N6,N6,N6-trimethyllysine, spermine, and hexosamine-valine-isoleucine-OH) could differentiate IR exposed individuals with high sensitivity and specificity (area under the receiver operating characteristic (AUROC) curves 0.89-1.00) irrespective of dose rate at both days. For serum, the top 25 significant lipids affected by IR exposure showed slightly higher perturbations at 0.7 Gy/min vs. 7 Gy/s; however, identical panels showed excellent sensitivity and specificity at 1 d (three hexosylceramides (16:0), (18:0), (24:0), sphingomyelin [26:1], lysophosphatidylethanolamine [22:1]). Mice could not be differentiated from control samples at 7 d for a 3 Gy exposure based on serum lipid signatures. As with LDR exposures, we found that identical biofluid small molecule signatures can identify IR exposed individuals irrespective of dose rate, which shows promise for more universal applications of metabolomics for biodosimetry.
Project description:Expression profiles in mouse liver exposed to long-term gamma-irradiation were examined to assess in vivo effects of low dose-rate radiation. Three groups of male C57BL/6J mice were exposed to whole body irradiation at dose-rates of 17-20 mGy/day, 0.86-1.0 mGy/day or 0.042-0.050 mGy/day for 401-485 days (cumulative doses were approximately 8 Gy, 0.4 Gy or 0.02 Gy, respectively). Expression profiles were produced for RNA isolated from irradiated individual animals and for pooled RNA from sham-irradiated 3 animals for control. The expression levels of 6 irradiated animals for each dose were compared individually with those of 2 pooled controls (3 irradiated samples to one pooled control in first and second experiments).
Project description:Expression profiles in mouse liver exposed to long-term gamma-irradiation were examined to assess in vivo effects of low dose-rate radiation. Three groups of male C57BL/6J mice were exposed to whole body irradiation at dose-rates of 17-20 mGy/day, 0.86-1.0 mGy/day or 0.042-0.050 mGy/day for 401-485 days (cumulative doses were approximately 8 Gy, 0.4 Gy or 0.02 Gy, respectively). Expression profiles were produced for RNA isolated from irradiated individual animals and for pooled RNA from sham-irradiated 3 animals for control. The expression levels of 6 irradiated animals for each dose were compared individually with those of 2 pooled controls (3 irradiated samples to one pooled control in first and second experiments). The experiments were conducted twice at similar dose-rates. In the first experiment, three groups of 8 weeks old male C57BL/6J mice were exposed to whole body irradiation at dose-rates of either 16.6 mGy/day (H1), 0.858 mGy/day (M1) or 0.042 mGy/day (L1) for 485 days (cumulative doses were 8030 mGy, 416 mGy or 20.6 mGy, respectively). In the second experiment, the doe-rates were slightly elevated as 20.0 mGy/day (H2), 1.000 mGy/day (M2) or 0.050 mGy/day (L2) for 401 days (doses were 8015 mGy, 401 mGy or 20 mGy, respectively). A group of control unirradiated mice were set for each experiment (C1, C2).