Post-radiation Exposure Research Articles

Abstract A011: Enhanced Radiosensitivity of Pancreatic Cancer Achieved through Inhibition of Cyclin-Dependent Kinase 1

Abstract Introduction: One of the major challenges in treating Pancreatic Ductal Adenocarcinoma (PDAC) is overcoming radioresistance. This study investigates the targeting of Cyclin-dependent kinase-1 (CDK1) through both genetic and pharmaceutical inhibition as a strategy to increase the radiosensitivity of PDAC cells. Methods: We conducted mass spectrometry and phosphoproteomics analyses to compare engineered radiation-resistant PDAC cell lines (MIA PaCa-2 and PANC-1) with their parental controls. Additionally, we examined the TCGA PDAC database to correlate clinical outcomes, such as overall survival (OS), with CDK1 mRNA expression levels in PDAC patients. Furthermore, we developed a microRNA-based TET-on inducible shRNA to specifically inhibit CDK1 expression in PDAC cell lines. In an orthotopic PDAC model, we evaluated the radiation sensitivity of PDAC tumors with or without doxycycline treatment. We also employed a selective CDK1 inhibitor, RO-3306, to target CDK1 activation, followed by in vitro experiments using immunoblotting, immunocytochemistry, and clonogenic assays. Results: Our phosphoproteomics analysis revealed a significant increase in phospho-CDK1 (Tyr15) levels in the radiation-resistant cell lines. High CDK1 expression was associated with poorer OS in PDAC patients. Additionally, we observed heightened CDK1 phosphorylation at the threonine tyrosine 14 (Tyr14) residue following radiation exposure. Through our in vivo and in vitro experiments, we demonstrated that CDK1 inhibition, in conjunction with radiation therapy, delayed tumor growth and enhanced radiosensitivity in PDAC cells. Treatment with RO-3306 caused a substantial shift of cells into the G2/M phase and disrupted DNA repair post-radiation exposure, further enhancing radiosensitivity. Conclusion: Our findings underscore the critical role of CDK1 in PDAC radioresistance. Targeting CDK1 in combination with radiotherapy shows promise for future exploration as a potential treatment strategy in PDAC. Citation Format: Stetson Van Matre, Saaimatul Huq, Lokesh Akana, Oscar Zuniga, Henrique Rodrigues, Adam Wolfe. Enhanced Radiosensitivity of Pancreatic Cancer Achieved through Inhibition of Cyclin-Dependent Kinase 1 [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr A011.

Acute Impacts of Ionizing Radiation Exposure on the Gastrointestinal Tract and Gut Microbiome in Mice.

Radiation therapy for abdominopelvic malignancies often results in damage to the gastrointestinal tract (GIT) and permanent changes in bowel function. An overlooked component of the pathophysiology of radiation-induced bowel injury is the role of the gut microbiome. The goal of this research was to identify the impacts of acute radiation exposure on the GIT and gut microbiome. C57BL/6 mice exposed to whole-body X-rays (0.1-3 Gy) were assessed for histological and microbiome changes 48 h post-radiation exposure. Within the ileum, a dose of 3 Gy significantly decreased crypt depth as well as the number of goblet cells, but increased overall goblet cell size. Overall, radiation altered the microbial distribution within each of the main phyla in a dose- and tissue-dependent manner. Within the Firmicutes phylum, high dose irradiation resulted in significant alterations in bacteria from the class Bacilli within the small bowels, and from the class Clostridia in the large bowels. The 3 Gy radiation also significantly increased the abundance of bacterial families from the Bacteroidetes phylum in the colon and feces. Overall, we identified various alterations in microbiome composition following acute radiation exposure, which could potentially lead to novel biomarkers for tracking patient toxicities or could be used as targets for mitigation strategies against radiation damage.

Study on the mechanism of mitigating radiation damage by improving the hematopoietic system and intestinal barrier with Tenebrio molitor peptides.

Research on plant and animal peptides has garnered significant attention, but there is a lack of studies on the functional properties of Tenebrio molitor peptides, particularly in relation to their potential mitigating effect on radiation damage and the underlying mechanisms. This study aims to explore the protective effects of Tenebrio molitor peptides against radiation-induced damage. Mice were divided into five groups: normal, radiation model, and low-, medium-, and high-dose Tenebrio molitor peptide (TMP) groups (0.15 g per kg BW, 0.30 g per kg BW, and 0.60 g per kg BW). Various parameters such as blood cell counts, bone marrow DNA content, immune organ indices, serum levels of D-lactic acid, diamine oxidase (DAO), endotoxin (LPS), and inflammatory factors were assessed at 3 and 15 days post gamma irradiation. Additionally, the intestinal tissue morphology was examined through H&E staining, RT-qPCR experiments were conducted to analyze the expression of inflammatory factors in the intestine, and immunohistochemistry was utilized to evaluate the expression of tight junction proteins ZO-1 and Occludin in the intestine. The findings revealed that high-dose TMP significantly enhanced the hematopoietic system function in mice post radiation exposure, leading to increased spleen index, thymus index, blood cell counts, and bone marrow DNA production (p < 0.05). Moreover, TMP improved the intestinal barrier integrity and reduced the intestinal permeability. Mechanistic insights suggested that these peptides may safeguard intestinal barrier function by downregulating the gene expression of inflammatory factors TNF-α, IL-1β, and IL-6, while upregulating the expression of tight junction proteins ZO-1 and Occludin (p < 0.05). Overall, supplementation with TMP mitigates radiation-induced intestinal damage by enhancing the hematopoietic system and the intestinal barrier, offering valuable insights for further investigations into the mechanisms underlying the protective effects of these peptides against ionizing radiation.

Investigation on the compositional and performance evolution of cement paste subjected to Xenon radiation

This study addresses the critical question of how Xenon radiation, simulating natural solar radiation, affects the compositional, structural, and mechanical properties of cement paste. This aim is to understand the micro-to macro-scale changes in cement paste subjected to such radiation, a key concern for the durability of construction materials in solar-intensive environments. Employing a comprehensive suite of analytical techniques, including XRD, TG, 29Si NMR, 1H NMR, CT, SEM, and Vickers hardness testing, we systematically analyze the changes in phase composition, bound water content, silicate chain length in C–S–H, microstructure, and micro-mechanical behavior before and after radiation exposure. Our research uncovers a substantial decomposition of ettringite and a discernible reduction in the bound water content within the cement paste post-radiation exposure. Crucially, we detected a significant elongation in the C–S–H chain length, with a peak increase observed at 6%. This elongation is coupled with an increase in pore coarseness and a proliferation of internal defects. These alterations collectively lead to a marked decrease in the material's mechanical strengths: we noted a reduction in flexural strength by up to 18% and in compressive strength by as much as 25% at the macroscopic level. This research thus provides essential insights into the design and development of high-durability cementitious materials for solar radiation-intensive environments, contributing to the advancement of sustainable and resilient infrastructure.

Galactic Cosmic Irradiation Alters Acute and Delayed Species-Typical Behavior in Male and Female Mice.

Exposure to space galactic cosmic radiation is a principal consideration for deep space missions. While the effects of space irradiation on the nervous system are not fully known, studies in animal models have shown that exposure to ionizing radiation can cause neuronal damage and lead to downstream cognitive and behavioral deficits. Cognitive health implications put humans and missions at risk, and with the upcoming Artemis missions in which female crew will play a major role, advance critical analysis of the neurological and performance responses of male and female rodents to space radiation is vital. Here, we tested the hypothesis that simulated Galactic Cosmic Radiation (GCRSim) exposure disrupts species-typical behavior in mice, including burrowing, rearing, grooming, and nest-building that depend upon hippocampal and medial prefrontal cortex circuitry. Behavior comprises a remarkably well-integrated representation of the biology of the whole animal that informs overall neural and physiological status, revealing functional impairment. We conducted a systematic dose-response analysis of mature (6-month-old) male and female mice exposed to either 5, 15, or 50 cGy 5-ion GCRSim (H, Si, He, O, Fe) at the NASA Space Radiation Laboratory (NSRL). Behavioral performance was evaluated at 72 h (acute) and 91-days (delayed) postradiation exposure. Specifically, species-typical behavior patterns comprising burrowing, rearing, and grooming as well as nest building were analyzed. A Neuroscore test battery (spontaneous activity, proprioception, vibrissae touch, limb symmetry, lateral turning, forelimb outstretching, and climbing) was performed at the acute timepoint to investigate early sensorimotor deficits postirradiation exposure. Nest construction, a measure of neurological and organizational function in rodents, was evaluated using a five-stage Likert scale 'Deacon' score that ranged from 1 (a low score where the Nestlet is untouched) to 5 (a high score where the Nestlet is completely shredded and shaped into a nest). Differential acute responses were observed in females relative to males with respect to species-typical behavior following 15 cGy exposure while delayed responses were observed in female grooming following 50 cGy exposure. Significant sex differences were observed at both timepoints in nest building. No deficits in sensorimotor behavior were observed via the Neuroscore. This study revealed subtle, sexually dimorphic GCRSim exposure effects on mouse behavior. Our analysis provides a clearer understanding of GCR dose effects on species typical, sensorimotor and organizational behaviors at acute and delayed timeframes postirradiation, thereby setting the stage for the identification of underlying cellular and molecular events.

Withaferin A, a steroidal lactone, selectively protects normal lymphocytes against ionizing radiation induced apoptosis and genotoxicity via activation of ERK/Nrf-2/HO-1 axis

Increasing use of ionizing radiation (IR) in medicine, industry, agriculture and research ensues potential health hazards if not used properly or contained effectively. However, radioprotectors which are effective in clinical and/or accidental radiation exposures are still elusive. In this direction, we have explored the radioprotective potential of Withaferin A, a plant withanolide, which was recently shown to be safe and well tolerated in cancer patients in a clinical trial and is also known to be a radio-sensitizer in cancer cells. Our results show that, Withaferin A (WA) protected only normal lymphocytes, but not cancer cells, against IR-induced apoptosis and offered radioprotection even when added post-radiation exposure. WA treatment led to significant inhibition of IR-induced caspase-3 activation and decreased IR-induced DNA damage to lymphocytes and bone-marrow cells. WA reduced intracellular ROS and GSH levels and only thiol based anti-oxidants could abrogate the radio-protective effects of WA, indicating a crucial role of cellular/protein thiols in its biological activity. The inability of WA-glutathione adduct to offer radioprotection further underscored the role of cellular thiols. WA induced pro-survival transcription factor, Nrf-2, and expression of cytoprotective genes HO-1, catalase, SOD, peroxiredoxin-2 via ERK. Further, WA administration could rescue mice against radiation induced mortality, DNA damage, increase in micro-nucleated polychromatic erythrocytes (mn-PCEs) and increased ratio of polychromatic erythrocytes (PCEs) to Normochromatic Erythrocytes (NCEs) in bone-marrow, demonstrating its potent in vivo the radio-protective efficacy. In conclusion, WA selectively protects normal cells against IR-induced apoptosis via activation of cytoprotective Nrf-2 pathway.

Molecular Imaging of Fibroblast Activity in Radiation-Induced Acute Myocardial Damage Using a [18F]AlF-Labeled Fibroblast Activation Protein Inhibitor, FAPI-04

<h3>Purpose/Objective(s)</h3> A previous retrospective analysis revealed increased [¹⁸F]AlF-NOTA-FAPI uptake in myocardial tissue of patients with esophageal squamous cell cancer (ESCC) treated with concurrent chemoradiotherapy (CCRT). The present study investigated and verified the feasibility of [¹⁸F]AlF-NOTA-FAPI positron emission tomography (PET)/computed tomography (CT) imaging for detecting radiation-induced myocardial damage (RIMD). <h3>Materials/Methods</h3> Myocardial FAPI uptake was analyzed before radiotherapy and during radiotherapy (36–50 Gy) in 13 ESCC patients treated with CCRT. In an animal study, a single dose of 50 Gy was delivered to the cardiac apex of female Wistar rats using conformal radiotherapy. RIMD model rats were scanned with [¹⁸F]AlF-NOTA-FAPI PET/CT weekly for 12 weeks, and then MRI was conducted. Dynamic, competition, and [¹⁸F]FDG PET/CT studies were performed on RIMD rats at 5 weeks post-radiation, and histopathological analyses were conducted. <h3>Results</h3> Three patients showed potentially increased FAPI uptake in myocardial tissue after radiotherapy. In the RIMD rat model, a significant increase in FAPI uptake in the damaged myocardium was observed from the 2nd week post-radiation exposure, with peak values observed in the 5th week. Significantly more intense tracer accumulation was observed in the damaged myocardial region than in remote myocardial tissue, as identified by decreased [¹⁸F]FDG uptake and confirmed by autoradiography, Masson's trichrome staining and immunohistochemical staining. The left ventricular ejection fraction (LVEF) remained unchanged from baseline at the 3rd week post-radiation exposure but was remarkably decreased compared with that in the control group at the 8th week. <h3>Conclusion</h3> An increase in myocardial uptake of [¹⁸F]AlF-NOTA-FAPI occurred in patients with ESCC after radiotherapy. These results indicated that FAPI PET/CT imaging can detect RIMD noninvasively and before a decrease in LVEF is detected, indicating the clinical potential of FAPI as a radiotracer for in vivo imaging of RIMD.

Early detection of radiation-induced myocardial damage by [18F]AlF-NOTA-FAPI-04 PET/CT imaging.

Retrospective analysis revealed increased [18F]AlF-NOTA-FAPI-04 uptake in the myocardium of patients with esophageal squamous cell cancer (ESCC) treated with concurrent chemoradiotherapy (CCRT). This study investigated and verified the feasibility of [18F]AlF-NOTA-FAPI-04 PET/CT for detecting radiation-induced myocardial damage (RIMD). Myocardial FAPI uptake was analyzed before and during radiotherapy in thirteen ESCC patients treated with CCRT. In the animal study, a single dose of 50Gy was delivered to the cardiac apex of Wistar rats (24 rats, including 16 RIMD model rats and 8 control model rats). RIMD model rats were scanned with [18F]AlF-NOTA-FAPI-04 PET/CT weekly for 12weeks, and left ventricular ejection fraction (LVEF) was measured by magnetic resonance imaging. Dynamic, blocking, and [18F]FDG PET/CT studies (4 rats/group) were performed on RIMD rats at 5weeks post-radiation, and histopathological analyses were conducted. Increased FAPI uptake in the myocardium was found after CCRT (1.53 ± 0.53 vs 1.88 ± 0.70, P = 0.015). In RIMD rats, significantly increased FAPI uptake in the damaged myocardium was observed from the 2nd week post-radiation exposure and peaked in the 5th week. Significantly more intense tracer accumulation was observed in the damaged myocardium than in the remote myocardium, as identified by decreased [18F]FDG uptake and confirmed by autoradiography, hematoxylin-eosin, Masson's trichrome, and immunohistochemical staining. The LVEF remained unchanged at the 3rd week post-radiation exposure but was remarkably decreased compared with that in the control group at the 8th week. Through clinical phenomena and animal experimental studies, this study indicated that [18F]AlF-NOTA-FAPI-04 PET/CT imaging can detect RIMD noninvasively and before a decrease in LVEF, indicating the clinical potential of [18F]AlF-NOTA-FAPI-04 as a PET/CT tracer for early monitoring of RIMD.

PO-632-06 REAL-TIME EX-VIVO RADIOTHERAPY IMPACTS ON PACEMAKER FUNCTION ARE MINIMAL

There is a paucity of data regarding the safety of radiotherapy in patients with pacemakers and the impact of linear accelerator parameters is unclear. To assess the function of pacemakers when exposed to different linear accelerator parameters. Pacemakers (2 single, 1 dual chamber) were exposed to radiation at dose rates 0.2-11.8Gy/min. Dose rate was modulated by adjusting the distance from the beam edge, linear accelerator pulse repetition rate (rep rate) and distance from source. Noise amplitude, pacemaker output, and device behavior during irradiation were assessed in VVI or DDD modes. Each device was irradiated 28 times for 10 seconds. Noise amplitude on bipolar (Bi) channel increased with dose rate (r2=0.3611, p<0.0001, B) and on unipolar (Uni) channel decreased with rep rate (r2 = 0.09, p<0.01; C). On both channels noise amplitude decreased with distance from field edge (Bi r2 = 0.53, p<0.01; Uni r2 = 0.42, p<0.01; D). No over-sensed events occurred in response to radiation induced background noise. Low frequency signals on the Uni and Bi channels were observed with beam on and off (E), resulting in over-sensed events only when directly in the radiation beam and sensing Uni. When directly in the beam, oversensing of A pacing on the V sensing Uni channel was observed leading to pacing inhibition (F). Post-radiation exposure interrogation was unremarkable revealing no evidence of device malfunction. Pacemaker malfunctions when directly in photon radiation beam are related to oversensing and crosstalk phenomena preferentially affecting the unipolar sensing channel. There was no evidence of long-term device malfunction upon repeated interrogations despite multiple exposures.

Cellular DNA effects of radiation and cancer risk assessment in cells with mitochondrial defects

Mitochondria play a key role in mediating non-targeted effects (NTE) post-radiation exposure. Mitochondrial DNA (mtDNA), due to its less efficient repair as compared to nuclear DNA, is more severely affected by radiation exposure and mutations in essential mtDNA genes can further exacerbate oxidative stress. Our objective was to evaluate the impact of mitochondrial defects on radiation-induced DDR and genomic instability, biomarkers that can foreshadow cancer development. To better understand this relationship, we used commercially available lymphoblastoid cell lines containing characterized mitochondrial mutations and studied the kinetics of DNA damage and relative telomere length (RTL) changes over time post 0.5 Gy X-ray exposure. Our work suggests that cells containing different mitochondrial mutations exhibit unique DNA damage and telomere length effects following radiation exposure. For example, a cell line containing a mitochondrial mutation in the ND4 subunit of complex 1 showed decreased growth rate, higher levels of persistent DNA damage, and telomere instability as compared to wild type. In contrast, a cell line with a mutation in the ATPase 6 mitochondrial protein showed more subtle negative alterations. These findings suggest mitochondrial integrity may play an important role in cellular changes that promote cancer. In total results indicate mitochondrial mutations can influence DNA damage kinetics and genomic instability and have long-term consequences in the ability to regain homeostasis following radiation exposure. These results may help explain, at least in part, the rationale for the persistent genomic instability often observed following a low dose of radiation and how it may promote cancer.

Effect of nuclear radiation on rat model of decompression sickness induced by large depth rapid floating escape

Objective: To investigate the effects of different doses of nuclei exposure at different time on morbidity, mortality, and damage indicators in a rat model of decompression sickness caused by rapid flotation escape at a large depth. Methods: Eighty male SD rats were randomly divided into blank control group, escape control group and six intervention groups (escape at 4 hours after 4 Gy radiation, escape at 4 hours after 6 Gy radiation, escape at 4 hours after 12 Gy radiation, escape at 8 hours after 4 Gy radiation, escape at 8 hours after 6 Gy radiation, escape at 8 hours after 12 Gy radiation). Rats in intervention groups were exposed to different doses of γ-ray (4,6,12 Gy, respectively), and then were carried out a large depth and rapid buoyancy escape experiment (maximum pressure depth of 150 m). The changes of lung W/D, spleen index and plasma IL-1β levels were analyzed. Results: Compared with the blank control group, decompression sickness incidence and mortality of rats in escape groups after nuclear exposure were increased significantly. In 4 Gy and 6 Gy irradiation groups, higher morbidity and mortality were observed in rats which escaped at 4 h post nuclear exposure when compared with rats in 8 h groups. Consistent with the changes in morbidity and mortality, the wet / dry ratio of lung tissue, the pathological damage of lung tissue, and the decrease of spleen index showed the same trends: the changes were obvious at 4 h after lower doses nuclear radiation (4 Gy and 6 Gy), not at 8 h. However, these indicators all changed markedly at 4 and 8 h after higher doses nuclear radiation (12 Gy). Plasma IL-1β levels were significantly increased in each post-radiation exposure group when compared with the blank control group and the exposed control group. Conclusion: Nuclear radiation-induced lung injury, the damaged immune function and elevated plasma inflammatory factor concentrations increase the risk of decompression sickness after rapid ascent.

Changes in the gut microbiome community of nonhuman primates following radiation injury

BackgroundComposition and maintenance of the microbiome is vital to gut homeostasis. However, there is limited knowledge regarding the impact of high doses of radiation, which can occur as a result of cancer radiation therapy, nuclear accidents or intentional release of a nuclear or radioactive weapon, on the composition of the gut microbiome. Therefore, we sought to analyze alterations to the gut microbiome of nonhuman primates (NHPs) exposed to high doses of radiation. Fecal samples were collected from 19 NHPs (Chinese rhesus macaques, Macaca mulatta) 1 day prior and 1 and 4 days after exposure to 7.4 Gy cobalt-60 gamma-radiation (LD70–80/60). The 16S V4 rRNA sequences were extracted from each sample, followed by bioinformatics analysis using the QIIME platform.ResultsAlpha Diversity (Shannon Diversity Index), revealed no major difference between pre- and post-irradiation, whereas Beta diversity analysis showed significant differences in the microbiome after irradiation (day + 4) compared to baseline (pre-irradiation). The Firmicutes/Bacteriodetes ratio, a factor known to be associated with disruption of metabolic homeostasis, decreased from 1.2 to less than 1 post-radiation exposure. Actinobacillus, Bacteroides, Prevotella (Paraprevotellaceae family) and Veillonella genera were significantly increased by more than 2-fold and Acinetobacter and Aerococcus genus were decreased by more than 10-fold post-irradiation. Fifty-two percent (10/19) of animals exposed to radiation demonstrated diarrhea at day 4 post-irradiation. Comparison of microbiome composition of feces from animals with and without diarrhea at day 4 post-irradiation revealed an increase in Lactobacillus reuteri associated with diarrhea and a decrease of Lentisphaerae and Verrucomicrobioa phyla and Bacteroides in animals exhibiting diarrhea. Animals with diarrhea at day 4 post-irradiation, had significantly lower levels of Lentisphaere and Verrucomicrobia phyla and Bacteroides genus at baseline before irradiation, suggesting a potential association between the prevalence of microbiomes and differential susceptibility to radiation-induced diarrhea.ConclusionsOur findings demonstrate that substantial alterations in the microbiome composition of NHPs occur following radiation injury and provide insight into early changes with high-dose, whole-body radiation exposure. Future studies will help identify microbiome biomarkers of radiation exposure and develop effective therapeutic intervention to mitigate the radiation injury.

LGM2605 Reduces Space Radiation-Induced NLRP3 Inflammasome Activation and Damage in In Vitro Lung Vascular Networks.

Updated measurements of charged particle fluxes during the transit from Earth to Mars as well as on site measurements by Curiosity of Martian surface radiation fluxes identified potential health hazards associated with radiation exposure for human space missions. Designing mitigation strategies of radiation risks to astronauts is critical. We investigated radiation-induced endothelial cell damage and its mitigation by LGM2605, a radioprotector with antioxidant and free radical scavenging properties. We used an in vitro model of lung vascular networks (flow-adapted endothelial cells; FAECs), exposed to gamma rays, low/higher linear energy transfer (LET) protons (3–4 or 8–10 keV/µm, respectively), and mixed field radiation sources (gamma and protons), given at mission-relevant doses (0.25 gray (Gy)–1 Gy). We evaluated endothelial inflammatory phenotype, NLRP3 inflammasome activation, and oxidative cell injury. LGM2605 (100 µM) was added 30 min post radiation exposure and gene expression changes evaluated 24 h later. Radiation induced a robust increase in mRNA levels of antioxidant enzymes post 0.25 Gy and 0.5 Gy gamma radiation, which was significantly decreased by LGM2605. Intercellular cell adhesion molecule-1 (ICAM-1) and NOD-like receptor protein 3 (NLRP3) induction by individual or mixed-field exposures were also significantly blunted by LGM2605. We conclude that LGM2605 is a likely candidate to reduce tissue damage from space-relevant radiation exposure.

Therapeutic proton irradiation results in apoptosis and caspase-3 activation in human peripheral blood lymphocytes

Background: Proton therapy is effective in controlling many cancer types, allowing to spare the normal tissues and limiting the risk of adverse effects. However, cellular and molecular mechanisms by which protons induce cell death are still not fully understood. The purpose of this study was to investigate apoptotic mode of cell killing in human peripheral blood lymphocytes (HPBL) exposed ex vivo to 60 MeV proton beam radiation. Methods: HPBL obtained from 5 healthy donors were irradiated ex vivo with 60 MeV protons in spread out Bragg peak (SOBP), in the dose range 0.3–4.0 Gy. The average proton dose rate was 0.075 Gy/s. After irradiation, HPBL were stained with Annexin V fluorescein isothiocyanate (V-FITC) at different time-points post-radiation exposure: 1, 4 and 24 hours. To assess caspase-3 activation following irradiation with protons, caspase-3 DEVD-R1100 Fluorometric assay was used. Results: The apoptotic cell fraction stained with Annexin V-FITC, analysed after 1 and 4 h post proton-irradiation showed a dose-response increase in cell death. After 24 h post radiation exposure, the apoptotic fraction of cells represented a similar trend as in 1 and 4 h but less pronounced. Caspase-3 activation measured after 6 h of proton irradiation was significantly higher (P Conclusions: The data clearly demonstrates that 60 MeV therapeutic proton beam induced cell-killing in HPBL via apoptotic cell mode of death appears to be mediated by caspase-3 activation.

Magnitude and duration of immune checkpoint up-regulation and changes in the immune microenvironment post chemo-radiation (CRT) in esophageal cancer.

4060 Background: PD-1 inhibitors in metastatic gastroesophageal cancer have demonstrated response rates of approximately 25%. Unfortunately, the majority of patients do not respond. Therefore, a rationale strategy of combining immunotherapeutic agents with CRT in earlier stage esophageal cancer may prevent metastatic disease in a greater proportion of patients. This study assessed the impact of CRT on the immune microenvironment and the expression patterns of multiple immune checkpoints to optimally design neoadjuvant clinical trials. Methods: To determine the effects of CRT on resected esophageal adenocarcinomas (EAC), we examined the immune microenvironment pre and post CRT using IHC, LCM followed by qRT-PCR, and functional analysis of tumor-infiltrating lymphocytes. Additionally, to assess the duration and dependency of radiation-induced PD-L1 sensitization, esophagojejunostomy were performed on rats to induce gastroduodenoesophageal reflux and EAC formation. First, tumor bearing animals were dosed with single fraction 13 Gy or 16 Gy radiation to determine safety, dose correlation, and PD-L1 sensitization using qRT-PCR post-radiation. Next, longitudinal PD-L1 expression levels within individual tumor bearing animals were determined using serial endoscopic biopsies at baseline, 1, 5 and 9 weeks post 16 Gy radiation. Results: The majority of cancers displayed enhanced interferon γ and activated CD8+ T lymphocytes at the tumor stroma interface. These tumors also demonstrated enhanced upregulation of PD-L1 and multiple other immune checkpoints including – TIM3, GITR, IDO1, LAG3, CD137, OX40 and KIR. The animal model results indicated PD-L1 upregulation is dose dependent and transiently elevated post radiation exposure. Conclusions: Collectively, these findings provide insights into the evolving immune landscape after CRT and have significant implications for future neoadjuvant trial designs that will combine radiotherapy with immune checkpoint inhibitors. Currently, we are conducting a neoadjuvant trial assessing Nivolumab or Nivolumab/Ipilimumab in combination with CRT in stage II/III operable esophageal cancer.

Imaging Radiation-Induced Gastrointestinal, Bone Marrow Injury and Recovery Kinetics Using 18F-FDG PET.

Positron emission tomography using 18F-Fluro-deoxy-glucose (18F-FDG) is a useful tool to detect regions of inflammation in patients. We utilized this imaging technique to investigate the kinetics of gastrointestinal recovery after radiation exposure and the role of bone marrow in the recovery process. Male Sprague-Dawley rats were either sham irradiated, irradiated with their upper half body shielded (UHBS) at a dose of 7.5 Gy, or whole body irradiated (WBI) with 4 or 7.5 Gy. Animals were imaged using 18F-FDG PET/CT at 5, 10 and 35 days post-radiation exposure. The gastrointestinal tract and bone marrow were analyzed for 18F-FDG uptake. Tissue was collected at all-time points for histological analysis. Following 7.5 Gy irradiation, there was a significant increase in inflammation in the gastrointestinal tract as indicated by the significantly higher 18F-FDG uptake compared to sham. UHBS animals had a significantly higher activity compared to 7.5 Gy WBI at 5 days post-exposure. Animals that received 4 Gy WBI did not show any significant increase in uptake compared to sham. Analysis of the bone marrow showed a significant decrease of uptake in the 7.5 Gy animals 5 days post-irradiation, albeit not observed in the 4 Gy group. Interestingly, as the metabolic activity of the gastrointestinal tract returned to sham levels in UHBS animals it was accompanied by an increase in metabolic activity in the bone marrow. At 35 days post-exposure both gastrointestinal tract and bone marrow 18F-FDG uptake returned to sham levels. 18F-FDG imaging is a tool that can be used to study the inflammatory response of the gastrointestinal tract and changes in bone marrow metabolism caused by radiation exposure. The recovery of the gastrointestinal tract coincides with an increase in bone marrow metabolism in partially shielded animals. These findings further demonstrate the relationship between the gastrointestinal syndrome and bone marrow recovery, and that this interaction can be studied using non-invasive imaging modalities.

Reduction of radiation-induced nitrative stress in leucocytes and kidney cells of rats upon administration of polyphenolic complex concentrates from red wine

The research has shown that exposure to ionizing radiation at the dose of 30 cGy leads to the activation of NO-synthase way of nitrogen oxide synthesis, as well as to the accumulation of its stable metabolites and 3’-nitrotyrosine modified proteins in rat peripheral blood leucocytes and the renal cortical layer. NO-synthase activity was preserved at the control value through the consumption of red wine natural polyphenolic complex concentrates by the irradiated animals. The content of proteins modified by tyrosine nitration decreased in the early period of post-radiation exposure due to the influence of the investigated concentrate. Thus the ability of red wine natural polyphenolic complex concentrates to prevent adverse changes in L-arginine/NO system and, therefore, inhibit the development of nitrative stress induced by low doses of ionizing radiation has been proved experimentally.

Therapeutic Effects of Olive Leaf Extract or Bone Marrow Mesenchymal Stem Cells against Lung Damage Induced in Male Albino Rats Exposed to Gamma Radiation

Aim of the work- This study aimed to investigate the histological and histochemical changes in the lung tissue of male albino rats post exposure to gamma radiation and the possible therapeutic effect of both olive leaf extract and bone marrow mesenchymal stem cells. Matrerial and methods-The current study was carried out on 40 adult male albino rats (Sprague dawely strain); they were divided equally into 5 groups (C group: control rats; O group : rats treated with olive leaves extract( 15 mg /kg body weight/daily) ; R group: rats exposed to a single dose of gamma-radiation(3 Gy); RO group: rats of this group treated with olive extract 15 mg /kg body weight/daily one week before and one week after irradiation; RS group: rats of this group irradiated with 3Gy then treated with bone marrow mesenchymal stem cells ( BMSCs) 3×106 cells/ml suspension through caudal vein about 5h post radiation exposure. Histopathological and histochemical changes were studied. Results-Rats exposed to gamma radiation showed numerous histological and histochemical changes, these changes were ameliorated by using either olive leaf extract or bone marrow mesenchymal stem cells. BMSCs showed more obvious therapeutic effect than olive leaf extract. Conclusion-The present work showed that olive leaf extract or bone marrow mesenchymal stem cells (BMSCs) have lung tissue radiotherapeutic effects against whole body gamma radiation in male albino rats.

Telomere shortening: a new prognostic factor for cardiovascular disease post-radiation exposure.

Telomere length has been proposed as a marker of mitotic cell age and as a general index of human organism aging. Telomere shortening in peripheral blood lymphocytes has been linked to cardiovascular-related morbidity and mortality. The authors investigated the potential correlation of conventional risk factors, radiation dose and telomere shortening with the development of coronary artery disease (CAD) following radiation therapy in a large cohort of Hodgkin lymphoma (HL) patients. Multivariate analysis demonstrated that hypertension and telomere length were the only independent risk factors. This is the first study in a large cohort of patients that demonstrates significant telomere shortening in patients treated by radiation therapy who developed cardiovascular disease. Telomere length appears to be an independent prognostic factor that could help determine patients at high risk of developing CAD after exposure in order to implement early detection and prevention.

Radiation-Induced Trapped Charging Effects in SiC Power MOSFETs

Commercial SiC MOSFETs were exposed to ionizing radiation to characterize the radiation response and to compare the observed threshold voltage (VT) instability post-radiation exposure, with the VT instability following bias temperature stress (BTS) testing. As expected, a large number of positively charged oxide traps were present in these devices following irradiation, resulting in a significant negative VT shift. However, the observed VT instability following irradiation was much smaller than that for similarly processed devices exposed to a BTS. Irradiated devices subjected to unbiased thermal treatments experienced a significant annealing of trapped holes above 100 °C. However, isochronal annealing treatments did not significantly alter the number of switching oxide traps, suggesting that a large portion of the traps activated by irradiation may lie deeper within the SiO2, beyond the tunneling distance from the SiC.