Radiation exposure can result in various complications influenced by factors such as dose, the amount of tissue exposed, and the type of tissue exposed. Radiation-induced liver injury (RILI) is a concern in cancer patients receiving thoracic and upper abdominal radiation, but it can also be a risk for civilians exposed to radiation in a nuclear event. RILI can lead to organ dysfunction or death; a deeper understanding of how radiation causes damage to normal tissue could pave the way for new treatments. In our study, we focused on the effects of radiation on the two main liver cell types: liver sinusoidal endothelial cells (LSECs) and hepatocytes. We exposed these cells to different doses of radiation (2, 4 or 8 Gy) as well as a sham irradiation (0 Gy) control. Proteins were extracted at 30 min, 6 h and 24 h postirradiation and analyzed using reverse phase protein array (RPPA). We observed changes to the Hepatic fibrosis signaling pathway, IL-8 signaling, and S100 family signaling pathways across multiple doses and time points in LSECs. In hepatocytes, radiation affected different pathways; we see changes in the Th1 and Th2 signaling pathways and the IL-10 signaling pathway. These pathways are critical in mediating the immune response, with Th1 being associated with pro-inflammatory responses and Th2 with anti-inflammatory responses. Hub proteins from protein-protein interaction (PPI) networks across all time points for both LSECs and hepatocytes highlighted EGFR as a top-ranked protein, indicating the potential role in mitigating radiation damage in liver cells. Herein, we showed alterations in protein expression after RILI using RPPA at early time points (hours to days) to determine potentially targetable molecular pathways. We further highlighted potential therapeutic protein markers, including EGFR, as an example of the potential utility of RPPA in target discovery.

Well-characterized animal models of acute radiation syndrome are needed for the development of radiation medical countermeasures to mitigate injury due to acute exposure to high doses of total- or partial-body radiation. Such animal models must reveal a radiation dose- and time-dependent relationship, pathogenesis of injury, and clinical presentation similar to humans. The focus of this study was to investigate clinical responses, principally lethality patterns, of cynomolgus macaques acutely exposed to relatively high doses of total-body radiation. Such investigations are currently relevant due to the limited availability of rhesus macaques, the dominant and preferred macaque subspecies, due to limited supply and their use in other high-priority areas. In this study employing cynomolgus macaques, a preliminary dose-response relationship was determined using three different radiation doses (4.7, 5.8 and 6.5 Gy, n = 24, n = 8/radiation dose) at a dose rate of 0.6 Gy/min. Animals were provided subject-based supportive care excluding blood products and were monitored for 60 days postirradiation for survival, which was the primary endpoint and the secondary endpoint was hematopoietic recovery. The lethality curve suggested LD_30/60, LD_50/60, and LD_70/60 values as 4.8, 5.3, and 5.8 Gy, respectively. The initial results of this study are deemed critical for future efficacy assessments of newly developed medical countermeasures for acute radiation injuries by making use of an alternative subspecies of macaques, namely cynomolgus macaques (Macaca fascicularis).

Radiation therapy is a crucial adjunct treatment for head and neck tumors, as well as primary or metastatic brain tumors. Radiation-induced brain injury is one of the most severe complications, postirradiation, in patients with head and neck tumors, and significantly impacts their quality of life. Currently, there are no effective treatments for radiation-induced brain injury, making the study of radiation-induced molecular mechanisms and the identification of early damage biomarkers critical for the early diagnosis and treatment of such injuries. In this study, twelve male C57 mice aged 6–8 weeks were randomly divided into a control group, a 15 Gy irradiation group, and a 30 Gy irradiation group. Mice were exposed to 6 MV X rays. The control group underwent the same anesthesia procedure as the irradiated groups but did not receive radiation. General health and weight changes were monitored and recorded. Four months postirradiation, mice were subjected to intracranial magnetic resonance imaging [T2-weighted imaging (T2WI)], open field test (OFT), novel object recognition (NOR), followed by a collection of brain tissues for immunofluorescence, SA-β-gal staining, and transcriptomic and metabolomic analyses. Compared to the control group, the 15 Gy and 30 Gy irradiated mice showed reduced activity and weight loss. The irradiated mice exhibited impaired recognition memory in the NOR test and decreased body weight, but radiation had no significant effect on weight or performance in the OFT. Electron microscopy reveals significant demyelination of mouse cortex after irradiation, and MRI T2-weighted imaging demonstrated varying degrees of brain atrophy and ventricular enlargement in irradiated mice compared to the control group. Immunofluorescence staining showed a significant increase in astrocytes and microglia activated after irradiation. SA-β-gal staining revealed significant increases in the numbers of b-gal1 cells in irradiated mice compared to those in untreated control mice. Bioinformatics analysis identified enriched pathways primarily related to lipid metabolism and neuroinflammatory responses; associated metabolites and genes were variously upregulated or downregulated. The findings suggest that radiation-induced brain injury involves complex biological processes, with lipid metabolism disorders and neuroinflammation being the predominant pathological changes observed. Further studies on these metabolic pathways and genes could enhance our understanding of the pathogenic mechanisms underlying radiation-induced brain injury and identify potential therapeutic targets.

The development of quantitative models that correlate physical, chemical, and biological parameters with radiobiological effects is imperative in the domains of radiotherapy and radiation protection. Due to the challenges associated with quantifying underlying mechanisms, phenomenological models are frequently established in preference to mechanistic models. However, the lack of a universal methodology for constructing phenomenological models presents a significant challenge in the field. We employ symbolic regression as a method for constructing phenomenological models. We attempt to develop models for the survival fraction, microdosimetric parameters, the radiation oxygen effect, and the FLASH effect. Additionally, we compare the results obtained from our symbolic regression approach with existing formulas in the scientific literature to assess the efficacy and validity of our method. Symbolic regression yields multiple simple formulas for each modeling task undertaken. These formulas demonstrate a comparable ability to predict radiobiological effects as the formulas presented in previous scientific publications. Our findings propose that symbolic regression is an automated and flexible strategy for constructing phenomenological models of radiobiological effects. Additionally, they underscore that the interpretability of a model is as crucial as its goodness of fit, as symbolic regression can identify various distinct formulas that adequately fit the provided data points.

Ciprofloxacin (CIP) was found to enhance pegylated G-CSF therapy (PEG, Neulasta^®)-induced survival from 30% to 85% after ionizing radiation exposure. This combined therapy significantly mitigated radiation-induced brain hemorrhage through its capability to improve platelet recovery. This study tested whether this combined treatment also mitigated gastrointestinal damage from radiation. B6D2F1 female mice were exposed to ⁶⁰Co c radiation. CIP was fed daily to mice for up to 14 days. PEG was injected on day 1, and then weekly up to day 14. For the early time point study, blood, femurs, spleen, and ileum were collected on days 2, 4, 9, and 15 postirradiation. Bone marrow cells were counted; spleen weights and splenocyte counts were measured; and ileum histopathology was examined and analyzed. AKT, ERK, JNK, p38, claudin 2, NF-kB, Bax, Bcl-2, and gasdermin D were measured in ileum lysates using Western blotting while miR-34a was measured by reverse transcription followed by real-time-PCR, and citrulline was measured by colorimetric assay. In serum, interleukin-18 (IL-18) was measured by Luminex assay and complement protein 3 (C3) was detected by ELISA. The bacterial DNA load in livers was measured by real-time PCR. Radiation depleted bone marrow cells in femurs beginning day 2 through day 15 postirradiation, which was mitigated by PEG or CIP1PEG on day 9 through day 15 and by CIP on day 15, respectively. Radiation exposure led to decreased spleen weight on day 2 through day 15, while PEG or CIP1PEG significantly mitigated the reduction on day 9 through day 15. Radiation exposure reduced splenocyte counts on day 2 through day 15 postirradiation, but that was mitigated by PEG or CIP1PEG on day 15. Ileum histology showed that radiation decreased villus height on day 2 through day 15; CIP mitigated the reduction on day 15, whereas PEG1CIP mitigated it on day 2 through 15. Villus widths were increased on day 2 through day 15, while PEG1CIP effectively decreased them on day 4 through day 15. Crypt depth was reduced by radiation on day 2, but returned to the baseline on day 4 through 15. CIP or CIP1PEG transiently increased the depth only on day 4. Crypt counts were reduced by radiation on days 2 and 4, but returned to the baseline on days 9 and 15, regardless of individual drugs or combinations. Citrulline data confirmed the villus height recovery. Radiation significantly increased pro-inflammatory cytokine IL-18 on days 4 and 9, which was mitigated by PEG alone or PEG1CIP, but not by CIP alone. Radiation increased C3 on day 9 in ileum and serum. The serum C3 was positively associated with the serum IL-18 levels and negatively correlated with the crypt depth. Radiation-induced decreases in claudin 2 (a tight junction marker) in ileum and increases in bacterial DNA in livers were mitigated by PEG1CIP. Radiation did not reduce NF-kB and its activation but reduced Bcl-2 expression, which was not significantly recovered by any individual drug or combination. However, the PEG and CIP combination significantly decreased NF- kB and BAX. In contrast, radiation increased miR-34a and cleaved gasdermin D, which CIP1PEG effectively mitigated. This was confirmed by immunohistochemistry. The results taken together suggest that PEG1CIP combined treatment was effective in mitigating the radiation-induced bone marrow, spleen, and ileum injury. The mitigative effect of this combined treatment was mediated by increases in G-CSF levels that suppress miR-34a, thereby probably leading to decreased gasdermin D-mediated pyroptosis.

This research details the synthesis, structure-activity evaluation, and analysis of novel oxadiazole-based compounds for visualizing b-amyloid (Ab) in Alzheimer's disease (AD). The derivatives exhibited binding affinities to Ab aggregates in vitro. The [¹⁸F]-labeled compounds, [¹⁸F]4-(5-(4-Fluorophenyl)-1,3,4-oxadiazol-2-yl)-N, N-dimethylaniline (compound [¹⁸F] 3) and [¹⁸F] 4-(5-(4-Fluorophenyl)-1,3,4-oxadiazol-2-yl)-N-methyl-aniline (compound [¹⁸F]4), effectively labeled Ab plaques in brain sections from Alzheimer's disease patients and APP/PS1 mice. In dynamic positron emission tomography (PET) studies on healthy mice, these compounds demonstrated favorable brain uptake followed by clearance. Additional structural alterations to compounds [¹⁸F] 3 and [¹⁸F] 4 may lead to the development of more efficient PET tracers for precise visualization of Ab plaques.