137Cs Irradiation Research Articles

Gamma irradiation system's performance tests.

This study reviews the performance analysis of a 137Cs irradiation system that has recently been installed in the laboratory of Uzbek National Institute of Metrology. The laboratory is responsible for calibrating calibration facilities and for calibrating most protection level radiation monitoring instruments used in medical, nuclear, industrial and academic settings in Uzbekistan. This system employs the most advanced radiation safety standards, along with 21st century source automation methods. In this work, we review the system's performance according to ISO 4037 and present measurement uncertainty budget. Our analysis shows excellent results in terms of scattered radiation, beam uniformity and field size, change in source position, test for source impurities, chamber stability and source calibration, and all these parameters fully comply with the requirements of ISO 4037.

Imaging the radioprotective effect of amifostine in the developing brain using an apoptosis-reporting transgenic zebrafish

Purpose Normal tissue radioprotectants alleviate radiation-induced damages and preserve critical organ functions. Investigating their efficacy in vivo remains challenging, especially in enclosed organs like the brain. An animal model that enables direct visualization of radiation-induced apoptosis while possessing the structural complexity of a vertebrate brain facilitates these studies in a precise and effective manner. Materials and methods We employed a secA5 transgenic zebrafish expressing secreted Annexin V fused with a yellow fluorescent protein to visualize radiation-induced apoptosis in vivo. We developed a semi-automated imaging method for standardized acquisition of apoptosis signals in batches of zebrafish larvae. Using these approaches, we studied the protective effect of amifostine (WR-2721) in the irradiated zebrafish larval brain. Results Upon 2 Gy total-body 137Cs irradiation, increased apoptosis could be visualized at high resolution in the secA5 brain at 2, 24, and 48 hour post irradiation (hpi). Amifostine treatment (4 mM) during irradiation reduced apoptosis significantly at 24 hpi and preserved Wnt active cells in the larval brain. When the 2 Gy irradiation was delivered in combination with cisplatin treatment (0.1 mM), the radioprotective effect of amifostine was also observed. Conclusions Our study reveals the radioprotective effect of amifostine in the developing zebrafish larval brain, and highlights the utility of secA5 transgenic zebrafish as a novel system for investigating normal tissue radioprotectants in vivo.

Crystal growth and characterization of mixed elpasolite scintillators Ce:Cs2Li(LaBr6)x(YCl6)1-x (0 < x ≤ 0.4)

Over the past two decades, substantial research has been done on the typical elpasolite scintillators Ce:Cs2LiYCl6 (CLYC) and Ce:Cs2LiLaBr6 (CLLB) for their potential use as neutron/gamma dual-mode detectors. Commonly, the cation or anion alloying will change the luminescence and scintillation properties of the scintillators, such as the good energy resolution of the Ce:Cs2LiLa(Br–Cl)6 (CLLBC) crystal. In this work, ⌀8 mm Ce:Cs2Li(LaBr6)x(YCl6)1-x crystals with x = 0.1, 0.2, 0.3 and 0.4 were grown by the vertical Bridgman technique. Then, ⌀25 mm Ce:Cs2LiLa0.1Y0.9Br0.6Cl5.4 crystal was grown for its relatively high optical quality and phase purity. The luminescence and scintillation properties were also investigated. The energy resolution of Ce:Cs2LiLa0.1Y0.9Br0.6Cl5.4 crystal was calculated to be 9.3%. The scintillation decay time were 38 ns and 623 ns under 137Cs irradiation.

Discovery of the radio-protecting effect of Ecliptae Herba, its constituents and targeting p53-mediated apoptosis invitro and in vivo.

Radiation protection drugs are often accompanied by toxicity, even amifostine, which has been the dominant radio-protecting drug for nearly 30 years. Furthermore, there is no therapeutic drug for radiation-induced intestinal injury (RIII). This paper intends to find a safe and effective radio-protecting ingredient from natural sources. The radio-protecting effect of Ecliptae Herba (EHE) was discovered preliminarily by antioxidant experiments and the mouse survival rate after 137Cs irradiation. EHE components and blood substances invivo were identified through UPLC‒Q-TOF. The correlation network of "natural components in EHE-constituents migrating to blood-targets-pathways" was established to predict the active components and pathways. The binding force between potential active components and targets was studied by molecular docking, and the mechanism was further analyzed by Western blotting, cellular thermal shift assay (CETSA), and ChIP. Additionally, the expression levels of Lgr5, Axin2, Ki67, lysozyme, caspase-3, caspase-8,8-OHdG, and p53 in the small intestine of mice were detected. It was found for the first time that EHE is active in radiation protection and that luteolin is the material basis of this protection. Luteolin is a promising candidate for RⅢ. Luteolin can inhibit the p53 signaling pathway and regulate the BAX/BCL2 ratio in the process of apoptosis. Luteolin could also regulate the expression of multitarget proteins related to the same cell cycle.

Dosimetric Study of Heat-Treated Calcium-Aluminum-Silicon Borate Dosimeter for Diagnostic Radiology Applications.

The production of thermoluminescence (TL) dosimeters fabricated from B2O3-CaF2-Al2O3-SiO2 doped with Cu and Pr for use in diagnostic radiology is the main goal of this research. The TL samples were synthesized via the melt-quench technique processed by melting the mixture at 1200 °C for 1 h, and, after cooling, the sample thus created was divided into two samples and retreated by heating for 2 h (referred to as TLV30) and for 15 h (referred to as TLV17). SEM and EDS analyses were performed on the TL samples to confirm the preparation process and to investigate the effects of irradiation dosimetry on the TL samples. Furthermore, the TL samples were irradiated with γ-rays using a 450 Ci 137Cs irradiator and variable X-ray beams (5-70 mGy). Two important diagnostic radiology applications were considered: CT (6-24 mGy) and mammography (2.72-10.8 mGy). Important dosimetric properties, such as the glow curves, reproducibility, dose-response linearity, energy dependence, minimum dose detectability and fading, were investigated for the synthetized samples (TLV17 and TLV30), the results of which were compared with the Harshaw TLD-100. The TLV17 dosimeter showed higher sensitivity than TLV30 in all applied irradiation procedures. The dose-response linearity coefficients of determination R2 for TLV17 were higher than TLD-100 and TLV30 in some applications and were almost equal in others. The reproducibility results of TLV17, TLV30 and TLD-100 were less than 5%, which is acceptable. On the other hand, the results of the fading investigations showed that, in general, TLV17 showed less fading than TLV30. Both samples showed a significant decrease in this regard after the first day, and then the signal variation became essentially stable though with a slight decrease until the eighth day. Therefore, it is recommended to read the TL dosimeters after 24 h, as with TLD-100. The SEM images confirmed the existence of crystallization, whilst the EDS spectra confirmed the presence of the elements used for preparation. Furthermore, we noticed that TLV17 had grown dense crystals that were larger in size compared to those of TLV30, which explains the higher sensitivity in TLV17. Overall, despite the fading, TLV17 showed greater radiation sensitivity and dose-response linearity compared with TLD-100. The synthetized TL samples showed their suitability for use as dosimeters in diagnostic radiology radiation dosimetry.

Comparison and calibration of dose delivered by 137Cs and x-ray irradiators in mice

Objective. The Office of Radiological Security, U.S. Department of Energy's National Nuclear Security Administration, is implementing a radiological risk reduction program which seeks to minimize or eliminate the use of high activity radiological sources, including 137Cs, by replacing them with non-radioisotopic technologies, such as x-ray irradiators. The main goal of this paper is to evaluate the equivalence of the dose delivered by gamma- and x-ray irradiators in mice using experimental measurements and Monte Carlo simulations. We also propose a novel biophantom as an in situ dose calibration method. Approach. We irradiated mouse carcasses and 3D-printed mouse biophantoms in a 137Cs irradiator (Mark I-68) and an x-ray irradiator (X-Rad320) at three voltages (160 kVp, 225 kVp and 320 kVp) and measured the delivered radiation dose. A Geant4-based Monte Carlo model was developed and validated to provide a comprehensive picture of gamma- and x-ray irradiation in mice. Main Results. Our Monte Carlo model predicts a uniform dose delivered in soft-tissue for all the explored irradiation programs and in agreement with the absolute dose measurements. Our Monte Carlo model shows an energy-dependent difference between dose in bone and in soft tissue that decreases as photon energy increases. Dose rate depends on irradiator and photon energy. We observed a deviation of the measured dose from the target value of up to −9% for the Mark I-68, and up to 35% for the X-Rad320. The dose measured in the 3D-printed phantoms are equivalent to that in the carcasses within 6% uncertainty. Significance. Our results suggest that 320 kVp irradiation is a good candidate to substitute 137Cs irradiation barring a few caveats. There is a significant difference between measured and targeted doses for x-ray irradiation that suggests a strong need for in situ calibration, which can be achieved with 3D-printed mouse biophantoms. A dose correction is necessary for bone doses, which can be provided by a Monte Carlo calculation. Finally, the biological implications of the differences in dose rates and dose per photon for the different irradiation methods should be carefully assessed for each small-animal irradiation experiment.

Doses from external irradiation and ingestion of 134Cs, 137Cs and 90Sr of the population of Belarus accumulated over 35years after the Chernobyl accident.

This study considers the exposure of the population of the most contaminated Gomel and Mogilev Oblasts in Belarus to prolonged sources of irradiation resulting from the Chernobyl accident. Dose reconstruction methods were developed and applied in this study to estimate the red bone-marrow doses (RBMs) from (i) external irradiation from gamma-emitting radionuclides deposited on the ground and (ii) 134Cs, 137Cs and 90Sr ingestion with locally produced foodstuffs. The mean population-weighted RBM doses accumulated during 35years after the Chernobyl accident were 12 and 5.7mGy for adult residents in Gomel and Mogilev Oblasts, respectively, while doses for youngest age groups were 20-40% lower. The highest mean area-specific RBM doses for adults accumulated in 1986-2021 were 63, 56 and 46mGy in Narovlya, Vetka and Korma raions in Gomel Oblast, respectively. For most areas, external irradiation was the predominant pathway of exposure (60-70% from the total dose), except for areas with an extremely high aggregated 137Cs soil to cow's milk transfer coefficient (≥ 5.0Bq L-1 per kBq m-2), where the contribution of 134Cs and 137Cs ingestion to the total RBM dose was more than 70%. The contribution of 90Sr intake to the total RBM dose did not exceed 4% for adults and 10% for newborns in most raion in Gomel and Mogilev Oblasts. The validity of the doses estimated in this study was assessed by comparison with doses obtained from measurements by thermoluminescence dosimeters and whole-body counters done in 1987-2015. The methodology developed in this study can be used to calculate doses to target organs other than RBM such as thyroid and breast doses. The age-dependent and population-weighted doses estimated in this study are useful for ecological epidemiological studies, for projection of radiation risk, and for justification of analytical epidemiological studies in populations exposed to Chernobyl fallout.

Luminescence and scintillation properties of Ce-doped calcium hafnate perovskite single crystals

Hafnium-based materials are attractive for a scintillator owing to their high density and effective atomic number. In this study, single crystals of Ce-doped calcium hafnate perovskite (Ce:CaHfO3) were synthesized from a Ca-rich composition, and photoluminescence (PL) and scintillation properties were investigated. The X-ray diffraction patterns revealed that the synthesized single crystals were a single phase of CaHfO3. The Ce:CaHfO3 exhibited blue luminescence at 430 nm and fast decay due to the 5d–4f transition of Ce3+ in both PL and scintillation. From the measurement of pulse height spectra under 137Cs irradiation, the highest light yield of 7800 photons/MeV was observed in the 3% Ce:CaHfO3.

MORPHOLOGICAL AND IMMUNOHISTOCHEMICAL FEATURES OF PLACENTAL DAMAGE DUE TO THE INCORPORATION OF 137Cs.

to investigate the morphological and immunohistochemical features of placental damage due to theincorporation of 137Cs depending on the scenario of pregnancy completion. The study material consisted of placentas from 60 women with reproductive losses inanamnesis and signs of termination of the current pregnancy (first group) and placental samples from 30 women with an uncomplicated gestation and an unencumbered anamnesis (control group). The detailed study required the distribution of placental samples from the first group into subgroups. Subgroup 1a included 38 placentas from women who gave birth at 37-40 weeks, despite signs of termination of the current pregnancy. Subgroup 1b - placentas of 13 women who gave birth at a gestation period of 28-36 weeks + 6 days. Subgroup 1c - 9 placental samples from women who gave birth at a gestation period of 22-27 weeks + 6 days. The volumetric activity of the 137Cs in the placentas was measured using β-spectrometer. The histology of the placenta was studied using a standard technique. The following expressions were studied in placenta: CD31 / PECAM-1, CD45 / T200 / LCA, CD56 / NCAM-1, CEA / CD66e Ab-2, Vimentin, using indirect streptavidin peroxidase detection method. Placentas accumulate 137Cs. The different volumetric activity of the isotope correlates with scenarios of pregnancy. Due to the action of incorporated 137Cs with a specific mass of more than 1.1 Bq/kg, placental dysfunction develops. The consequences of placental dysfunction depend on the volumetric activity of the 137Cs and the preservation of adaptive and compensatory reactions in the placenta. Morphological and immunohistochemical features of placental damage to incorporated 137Cs were established, depending on the scenario of completion of pregnancy. A marker of unfavorable completion of pregnancy is the expression of a carcinoembryonic antigen (CEA) in the placenta. Premature termination of pregnancy (PTP) is a multifactorial pathology associated with pathological changes in immune and neuroendocrine regulation and hereditary, infectious, and environmental factors that disrupt the adaptation mechanisms in the mother-placenta-fetus system. Intraplacental irradiation of 137Cs is one of the factors in the multifactorial nature of reproductive losses. As a result of intraplacental irradiation of 137Cs, the architecture of the placenta is disturbed, the activity of pro-inflammatory cytokines CD45 and CD56 increases, and the coagulation cascade is activated. Extreme effects depend on the volumetric activity of the isotope incorporated in the placenta and the organ's compensatory capacity. Accumulation of up to 1.0 Bq/kg 137Cs does not affect the course of gestation. Internal irradiation with an activity of 4.5-10.4 Bq/kg 137Cs triggers late preterm labor. The nature of the damages corresponds to the category of «lesion of the maternal stroma» of the placenta. The volumetric activity of 137Cs over 10.4 Bq/kg is a probable cause of early preterm labor and antenatal fetal death. At the same time, the maternal and fetal structures of the placenta suffer damage. Expression of vimentin is a marker of placental destruction due to internal irradiation of 137Cs with a specific gravity of more than 4.5 Bq/kg. Expression of CEA in the structures of the placenta of women with PTP is a unique find and marker of premature birth and antenatal fetal death with intraplacental irradiation of 137Cs with an activity of more than 4.5 Bq/kg.

CYTOGENETIC STUDY OF MANIFESTATIONS OF THE UNIVERSAL PHENOMENON OF THE BYSTANDER RESPONSE.

to establish the level of chromosomal instability in peripheral blood lymphocytes (PBL) from healthyindividuals and cells from patients with B-cell chronic lymphocytic leukemia (CLL) under co-cultivation conditions and to determine the possibility of inducing manifestations of the universal phenomenon of bystander response in them. Cytogenetic analysis of uniformly stained chromosomes from human PBL, which differed by cytogenetic markers of sex; the presence of oncological transformation and in vitro irradiation of 137Cs in a dose of 0.50 Gy under the conditions of their joint cultivation was performed. The frequency of chromosome aberrations in PBL from healthy individuals when co-cultured with the blood from CLL patients was 3.35 per 100 cells, exceeded the control (1.48 per 100 cells, р < 0.01), did not significantly differ from the rate in non-irradiated blood T-lymphocytes from patients with B-cell CLL (3.18 per 100 cells, р > 0.05) and was lower than when co-cultivated with irradiated blood from CLL patients (5.00 per 100 cells, р < 0.01). In irradiated in vitro blood lymphocytes from CLL patients, the mean group level of chromosome aberrations under separate cultivation was 12.36 per 100 cells and exceeded the indicator during their co-cultivation with lymphocytes from healthy individuals (8.35 per 100 cells, р < 0.05). A tumor-induced bystander effect (TIBE) develops in PBL from healthy individuals when co-cultured with the blood from CLL patients and in T lymphocytes of B-cell CLL patients, the cytogenetic manifestation of which is an increase in the frequency of single chromatid fragments. The interaction of irradiated blood cells from CLL patients with lymphocytes from healthy individuals causes an increase in chromosomal instability in the latter due to the development of a radiation-induced bystander effect (RIBE) and leads to a decrease in the level of chromosomal instability in irradiated lymphocytes from CLL patients (rescue effect). An increase in the level of chromatid-type aberrations in T-lymphocytes of CLL patients during in vitro irradiation is a consequence of the development of RIBE against the background of TIBE.

Biofluid Metabolomics of Mice Exposed to External Low-Dose Rate Radiation in a Novel Irradiation System, the Variable Dose-Rate External 137Cs Irradiator

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.

Хромосомні аберації у лімфоцитах людини за зовнішнього та/або внутрішнього опромінення зразків крові 137Cs у модельних експериментах in vitro

The linear dependence of the yield of unstable chromosomal aberrations in human lymphocytes on the dose of prolonged external and/or internal irradiation of peripheral blood samples by 137Cs in the dose range of 0.09 - 0.54 Gy in vitro is presented. The higher cytogenetic efficiency of internal 137Cs irradiation is shown in comparison with external. It is shown that the cytogenetic efficiency of 137Cs in blood contamination is caused by influence on cells not only in the mitotic rest phase but during proliferation, within intracellular radioactivity through their cultivation. It is proposed to use the presented dose dependences of the yield of chromosomal aberrations in lymphocytes in vitro for human biological dosimetry during radiation accidents associated with prolonged external exposure or 137Cs incorporation to the body as a supplement to the results of physical dosimetry.

A performance analysis of a new secondary standard dosimetry laboratory irradiation system

This study reviews the performance analysis of a commercial 137Cs irradiation system that has recently been installed in the Secondary Standard Dosimetry Laboratory (SSDL) at the Soreq Nuclear Research Center (SNRC).The SSDL is responsible for calibrating calibration facilities and for calibrating most protection level radiation monitoring instruments used in medical, nuclear, industrial and academic settings in Israel. Until recently, these monitoring instruments have been calibrated by a 40-year-old irradiation system.At the end of 2018, a new Hopewell Designs Inc. ® irradiation system was installed at our SSDL. This system employs the most advanced radiation safety standards, along with 21st century source automation methods. In this work, we review the system’s performance. Our analysis shows excellent results in terms of repeatability, robustness, linearity, and beam uniformity. Additionally, the system accuracy was tested by participating in an international IAEA postal audit, and here too, excellent results were obtained.

Blocking the GITR-GITRL pathway to overcome resistance to therapy in sarcomatoid malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm originating from the pleura. Non-epithelioid (biphasic and sarcomatoid) MPM are particularly resistant to therapy. We investigated the role of the GITR-GITRL pathway in mediating the resistance to therapy. We found that GITR and GITRL expressions were higher in the sarcomatoid cell line (CRL5946) than in non-sarcomatoid cell lines (CRL5915 and CRL5820), and that cisplatin and Cs-137 irradiation increased GITR and GITRL expressions on tumor cells. Transcriptome analysis demonstrated that the GITR-GITRL pathway was promoting tumor growth and inhibiting cell apoptosis. Furthermore, GITR+ and GITRL+ cells demonstrated increased spheroid formation in vitro and in vivo. Using patient derived xenografts (PDXs), we demonstrated that anti-GITR neutralizing antibodies attenuated tumor growth in sarcomatoid PDX mice. Tumor immunostaining demonstrated higher levels of GITR and GITRL expressions in non-epithelioid compared to epithelioid tumors. Among 73 patients uniformly treated with accelerated radiation therapy followed by surgery, the intensity of GITR expression after radiation negatively correlated with survival in non-epithelioid MPM patients. In conclusion, the GITR-GITRL pathway is an important mechanism of autocrine proliferation in sarcomatoid mesothelioma, associated with tumor stemness and resistance to therapy. Blocking the GITR-GITRL pathway could be a new therapeutic target for non-epithelioid mesothelioma.

Abstract 1389: Bismuth gadolinium nanoparticles enhance radiation therapy in hepatocellular carcinoma

Abstract Introduction: Primary cancers of the liver is the fourth most common cause of cancer-related deaths and the second most lethal tumor, with a 5-year survival rate of only 18%. Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Although HCC is a radiosensitive tumor, radiotherapy (RT) has had a limited role in therapy due to the sensitivity of normal liver parenchyma, thus minimizing radiation exposure is optimal. High atomic number nanoparticles (NP) like bismuth (Bi) and gadolinium (Gd) have been shown to be effective radiosensitizers. Exposure of NP to ionizing radiation leads to the emission of secondary electrons and photons that can damage cells by free radical components, resulting in radiation dose-enhancement. Here we synthesized a multifunctional theranostic NP containing both Bi and Gd (BiGdNP) that can act both as a radiosensitizer and as a bimodal contrast agent for T1 MRI and CT imaging. Materials and Methods: BiGdNP were synthesized using one-pot thermal decomposition of Bi(III) acetate and Gd(III) acetate. Morphology of the NP was characterized by transmission electron microscopy (TEM, JEOL) while Bi and Gd were quantified by inductively coupled plasma-mass spectrometry (ICP-MS, Agilent). Dose-dependent cytotoxicity of BiGdNP was assessed by alamarBlueTM assay. HepG2 cells with BiGdNP were irradiated at 0, 2, and 4 Gy using a 137Cs irradiator. Irradiated cells were incubated at 300 cells/well for 2 weeks. Surviving colonies (1 colony ≥50 cells) were fixed with 10% formalin and stained with 0.5% crystal violet for counting. Magnetic resonance imaging at 4.7 Tesla (Bruker) and micro-computed tomography imaging (GE Medical Systems) were performed on BiGdNP-injected C57BL/6 mice to evaluate liver uptake. Results: Synthesized BiGdNP have good size and shape uniformity with average size of 118 ± 16 nm. No significant difference in cell viability was observed with non-treated and BiGdNP-treated cells at a maximum concentration of 50 μg/mL (p&amp;gt;0.05, t test). This concentration was then used to treat the cells prior to gamma irradiation. In the absence of RT, no adverse effects were observed with BiGdNP-treated cells. For both the 2 and 4 Gy doses, surviving fractions in the BiGdNP-treated groups were decreased than non-treated groups (p&amp;lt;0.05, t test). In addition to radiosensitization, increasing the BiGdNP concentration resulted in increased radiopacity in μ- CT and shorter T1 relaxation time in MRI in vitro and contrast enhancement of the liver in both μ-CT and MRI following intravenous administration in vivo. Conclusion: BiGdNP in combination with RT is more efficient in reducing reproductive viability of HCC than RT alone. The added MRI/CT imaging modality can potentially aid in the visualization of tumor delineation to facilitate localized radiation treatment. Citation Format: Avinash Kakulavar, Raniv D. Rojo, Jossana A. Damasco, Marites P. Melancon, Joy V. Perez. Bismuth gadolinium nanoparticles enhance radiation therapy in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1389.

Efferocytosis by Paneth cells within the intestine

Apoptotic cells are quickly and efficiently engulfed and removed via the process of efferocytosis by either professional phagocytes, such as macrophages, or non-professional phagocytes, including epithelial cells.1,2 In addition to debris removal, a key benefit of efferocytosis is that phagocytes engulfing apoptotic cells release anti-inflammatory mediators3,4 that help reduce local tissue inflammation;5 conversely, accumulation of uncleared apoptotic cells predisposes to a pro-inflammatory tissue milieu.6-8 Due to their high proliferative capacity, intestinal epithelial cells (iECs) are sensitive to inflammation, irradiation, and chemotherapy-induced DNA damage, leading to apoptosis. Mechanisms of iEC death in the context of irradiation has been studied,9,10 but phagocytosis of dying iECs is poorly understood. Here, we identify an unexpected efferocytic role for Paneth cells, which reside in intestinal crypts and are linked to innate immunity and maintenance of the stem cell niche in the crypt.11,12 Through a series of studies spanning invitro efferocytosis, exvivo intestinal organoids ("enteroids"), and invivo Cre-mediated deletion of Paneth cells, we show that Paneth cells mediate apoptotic cell uptake of dying neighbors. The relevance of Paneth-cell-mediated efferocytosis was revealed exvivo and in mice after low-dose cesium-137 (137Cs) irradiation, mimicking radiation therapies given to cancer patients often causing significant apoptosis of iECs. These data advance a new concept that Paneth cells can act as phagocytes and identify another way in which Paneth cells contribute to the overall health of the intestine. These observations also have implications for individuals undergoing chemotherapy or chronic inflammatory bowel disease.

Study on the lower absolute measurement limit of air kerma from 137Cs source using a large-size cavity chamber

For the purpose of obtaining the lower absolute measurement limit of the air kerma in 137Cs γ-ray reference fields, a cavity chamber with a volume of 301.936(19) cm3 was designed and fabricated. The absolute measurement of the air kerma was performed at the minimum effective dose rate of the large-size cavity chamber in our 137Cs γ-ray reference field. With the help of the detailed Monte-Carlo (MC) simulations of the large-size cavity chamber and our 137Cs irradiation facility, the conversion coefficient from the cavity dose to the reference air kerma was calculated. And the obtained air kerma rate with the MC simulation method was 1.429(13) mGy/h. At the same condition, the measured air kerma rates with the cavity theory method and the substitute method were 1.428(13) mGy/h and 1.419(53) mGy/h, respectively. The measurement result with the full MC simulation method agrees with the other two measurement results within 0.07% and 0.70%, respectively. The combination of the large-size chamber and the full MC simulation method can help calibration laboratories achieve the absolute measurement of the low air kerma rate (such as 1.5 mGy/h) in the 137Cs γ-ray reference field.

VADER: a variable dose-rate external 137Cs irradiator for internal emitter and low dose rate studies

In the long term, 137Cs is probably the most biologically important agent released in many accidental (or malicious) radiation disasters. It can enter the food chain, and be consumed, or, if present in the environment (e.g. from fallout), can provide external irradiation over prolonged times. In either case, due to the high penetration of the energetic γ rays emitted by 137Cs, the individual will be exposed to a low dose rate, uniform, whole body, irradiation. The VADER (VAriable Dose-rate External 137Cs irradiatoR) allows modeling these exposures, bypassing many of the problems inherent in internal emitter studies. Making use of discarded 137Cs brachytherapy seeds, the VADER can provide varying low dose rate irradiations at dose rates of 0.1 to 1.2 Gy/day. The VADER includes a mouse “hotel”, designed to allow long term simultaneous residency of up to 15 mice. Two source platters containing ~ 250 mCi each of 137Cs brachytherapy seeds are mounted above and below the “hotel” and can be moved under computer control to provide constant low dose rate or a varying dose rate mimicking 137Cs biokinetics in mouse or man. We present the VADER design and characterization of its performance over 18 months of use.

Simulated Stereotactic Body Radiation Therapy (SBRT) of Patient-derived Non-small Cell Lung Cancer (NSCLC) Cultured by Conditional Reprogramming: Radiobiological Comparison with Established Cell Lines

Methods to predict individual patient tumor control by radiation therapy may lead to improved treatment outcomes in NSCLC. We used conditional reprogramming culture (CRC) to measure primary culture radiosensitivity parameters for large single and multiple radiation fractions employed in SBRT. Corresponding measurements were made in 4 established NSCLC lines. With IRB approval, resected tumor samples (n = 4; 2/4 proliferated) within 4 h of surgical excision were minced, enzymatically dissociated, and plated in CRC medium. Epithelial and mesenchymal phenotypes suggested by dual morphology were confirmed by Western blot for vimentin and β-catenin biomarkers. E and M populations were separated by differential trypsinization and plated for monolayer clonogenic assay in 96-well plates. Irradiation was by 137Cs irradiator at 0.6 Gy/min. Plates were stained and scored within 4 weeks of plating and clonogenic survivals were fitted to the linear-quadratic (LQ) model. Spheroid cultures were established in ultralow-attachment plates. Monolayer LQ parameters based on single-fraction survival curves (2-16 Gy) are shown in Table 1. Both α/β ratios and single-fraction sensitivities ranged widely, with SF (16 Gy) differing by 800-fold across tested cell lines. Notably, some surviving colonies of irradiated E cells developed M morphology. Effective survival measurements (5 or 10 fx of 2 Gy, 2-4 fx of 6 Gy, 2-3 fx of 8 Gy, 2 fx of 10 Gy) at 1 or 2 d intervals often differed from the effective survival fraction (ESF) predicted from the standard radiobiological assumption of equal effect per fraction. Primary L343E/M cells from one patient were intermediate in the spectrum of radiosensitivities for established NSCLC lines. Effective survivals for multiple conventional and SBRT fractions differed from those predicted by the time-independent biologically effect dose (BED), despite use of the measured α/β value rather than assuming α/β = 10. Reasons could include repopulation for conventional fractionation and incomplete repair of sublethal damage for large (≥ 6 Gy) fractions used for SBRT. Primary culture by the CRC method can be used to measure patient NSCLC radiosensitivity parameters and might, after clinical validation, provide an alternative to genomic personalization of radiation therapy.Abstract 3182; Table 1NSCLC Cellsα ± SEMβ±SEMα/βRESF* (2 Gy x 10)RESF (6 Gy x 3)L343M (1°)0.17 ± 0.030.020 ± 0.0098.518.30.39L343E (1°)0.12 ± 0.020.024 ± 0.0085.04.20.20A5490.06 ± 0.010.018 ± 0.0062.60.430.49H19750.30 ± 0.060.025 ± 0.01019.49.610.98 (8Gyx2)*RESF = Relative Effective Survival Fraction = (ESFmeas / ESFpred), where ESFpred = [SF(d)]n Open table in a new tab

Abstract 1746: The BET inhibitor JQ-1 enhances radio-sensitivity in pediatric cancer cell lines by sustained p-gH2AX expression and enhanced differentiation

Abstract Purpose: Pediatric high grade gliomas (HGG), high risk medulloblastomas (MB) and neuroblastomas (NB) are malignant neurological tumors with poor prognosis despite major advancements in current therapeutic interventions. The standard of care therapy for such high risk tumors includes surgical resection, when possible, and radio-therapy with or without chemo-therapy. Therapeutic failure may be due to radio- and/or chemo-resistance and the maintenance of an aggressive stem-like sub-population of cells within the bulk tumors. Epigenetic deregulation is implicated in pediatric neurological cancer malignancies where the bromo- and extra-terminal domain (BET) protein activity may play a role in histone H3K27 acetylation leading to tumorigenesis and radio-resistance. Methods and Results: We used the BET inhibitor JQ-1 to determine the radio-sensitizing effect on a panel of human pediatric neurological cancer cell lines including: NB (IMR-32 and SKNSH), MB (D556 and D283) and HGG (GBM01 and DIPG07). Cells were seeded 24 hours (h) before treatment with 1 µM dose of JQ-1 for an additional 24 h before irradiation (IR) with 6Gy (JL Shepherd Mark 1 137Cs Irradiator). IncuCyte (Essen Biosciences, Ann Arbor, MI) live cell imaging recorded cellular proliferation (confluency) over 6 days post IR, revealing that while single treatment with JQ-1 or 6Gy irradiation alone significantly reduced cell proliferation in all the tested cell lines, the combination of JQ-1 pre-treatment followed by 6Gy IR differentially impaired proliferation capacity in all cell lines except DIPG07 by further reducing cell proliferation. To determine the mechanism of radio-sensitization induced by JQ-1, Western blot and Immunofluorescence analysis revealed increased p-γH2AX foci at 24 h post IR in JQ-1 pre-treated cells. Furthermore, the stem cell maintenance and tumorigenic proteins OCT-4, MYCN, HSP90, L1-CAM, RAB5C and FABP5 were differentially expressed after JQ-1 treatment. Next we assessed the effect of JQ-1 on cellular migration and stem-cell maintenance using the ‘wound-healing' scratch and tumor-sphere self-renewal assays, respectively. Cell migration was significantly (P &amp;lt; 0.05) inhibited with JQ-1 in both human NB (IMR-32 and SKNSH) and MB (D556 and D283) cell lines. Tumor-sphere formation efficiency was significantly (P &amp;lt; 0.05) reduced in IMR-32, SKNSH, D556, D283 and DIPG cells after treatment with JQ-1. Morphological cellular differentiation, evidenced by long neurite extensions, was induced after JQ-1 treatment in the D556, IMR-32 and SKNSH cells. Conclusions: Our data show potent anti-stem cell activity as well as decreased proliferation, migration and enhanced radiosensitivity following JQ-1 treatment. These effects may be due to delayed DNA repair mechanisms, differential expression of stem cell maintenance and tumorigenic proteins and induced differentiation of the malignant cancer stem cells. Citation Format: Tamara Mary Abou-Antoun, Jad Abdallah, Amanda R. Khater, Sarra El-Soussi, Aysegul Balyimez, Shinjini Ganguly, Anthony Sandler, Omar Mian. The BET inhibitor JQ-1 enhances radio-sensitivity in pediatric cancer cell lines by sustained p-gH2AX expression and enhanced differentiation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1746.