Partial-body Irradiation Research Articles

P286] Study on semi-automatically evaluated micronucleus frequency changes in patients with prostate adenocarcinoma undergoing low and high dose rate brachytherapy

Purpose We compared the biological damaging effect of low and high dose rate brachytherapy (LDR and HDR) in healthy tissues of patients with prostate adenocarcinoma by following up the changes of DNA damage with cytokinesis-blocked micronucleus assay (CBMN) during and after the treatment. Methods The CBMN assay was proven by literature to be good indicator of received dose during partial-body radiotherapy. The first blood samples were collected preceding the radiation therapy and the next ones in regular intervals after the seed insertion (LDR) or the end of treatment (HDR) (once every 3 month during the first year). The automatic analysis (scanning and image processing) was conducted by a dedicated totally automatized microscopic system. Results We determined the MN frequency of 5 patients from each treatment group automatically and manually as well. We found that in order to ensure the reliability of the comparison of automatic scoring results an extra step has to be introduced for sample quality improvement. This way the tendency of MN frequency versus elapsed time became possible to be accurately identified and analysed for both brachytherapy techniques. Due to the relatively low whole-body equivalent dose, the best results were achieved with the user-supervised semi-automatic combined method which merges the advantages of the accuracy of manual revision and the rapidity of the automation. Conclusions Although the signal is comparable with the order of changes, the automation-aided evaluation decreased the achieved uncertainty and made it possible to identify a definite and significant tendency in the change of MN frequency for LDR and HDR as well. Acknowledgment This work has been carried out in the frame of VKSZ 14-1-2015-0021 Hungarian project supported by the National Research, Development and Innovation Fund.

Characterization of a partial-body irradiation model with oral cavity shielding in nonhuman primates

Purpose: Characterization of a novel partial-body irradiation (PBI) shielding strategy in nonhuman primates (NHP; rhesus macaques), aimed at protecting the oral cavity, with respect to various gastrointestinal acute radiation syndrome (GI-ARS) syndrome parameters as well as buccal ulceration development.Materials and methods: NHPs were irradiated using a Cobalt-60 gamma source, in a single uniform dose, ranging from 9–13 Gy and delivered at 0.60–0.80 Gy min−1. Animals were either partially shielded via oral cavity shielding (PBIOS) or underwent total-body irradiation (TBI).Results: Clinical manifestations of GI-ARS, and also radiation-induced hematology and clinical chemistry changes, following PBIOS were comparable to the PBI NHP GI-ARS model utilizing shielding of the distal pelvic limbs and were significantly milder than TBI at similar radiation doses. Nadir citrulline levels were comparable between PBIOS and TBI but signs of recovery appeared earlier in PBIOS-treated animals. The PBIOS model prevented oral mucositis, whereas the TBI model presented buccal ulcerations at all tested radiation dose levels.Conclusions: Taken together, these results suggest that the PBIOS model is a suitable alternative to traditional PBI. For GI-ARS investigations requiring orally administered medical countermeasures, PBIOS confers added value due to the prevention of oral mucositis over traditional PBI.

AN EXACT GOODNESS-OF-FIT TEST BASED ON THE OCCUPANCY PROBLEMS TO STUDY ZERO-INFLATION AND ZERO-DEFLATION IN BIOLOGICAL DOSIMETRY DATA.

The goal in biological dosimetry is to estimate the dose of radiation that a suspected irradiated individual has received. For that, the analysis of aberrations (most commonly dicentric chromosome aberrations) in scored cells is performed and dose response calibration curves are built. In whole body irradiation (WBI) with X- and gamma-rays, the number of aberrations in samples is properly described by the Poisson distribution, although in partial body irradiation (PBI) the excess of zeros provided by the non-irradiated cells leads, for instance, to the Zero-Inflated Poisson distribution. Different methods are used to analyse the dosimetry data taking into account the distribution of the sample. In order to test the Poisson distribution against the Zero-Inflated Poisson distribution, several asymptotic and exact methods have been proposed which are focused on the dispersion of the data. In this work, we suggest an exact test for the Poisson distribution focused on the zero-inflation of the data developed by Rao and Chakravarti (Some small sample tests of significance for a Poisson distribution. Biometrics 1956; 12 : 264-82.), derived from the problems of occupancy. An approximation based on the standard Normal distribution is proposed in those cases where the computation of the exact test can be tedious. A Monte Carlo Simulation study was performed in order to estimate empirical confidence levels and powers of the exact test and other tests proposed in the literature. Different examples of applications based on in vitro data and also data recorded in several radiation accidents are presented and discussed. A Shiny application which computes the exact test and other interesting goodness-of-fit tests for the Poisson distribution is presented in order to provide them to all interested researchers.

Evaluation of Different Formulations and Routes for the Delivery of the Ionizing Radiation Mitigator GS-Nitroxide (JP4-039).

The mitochondrial targeted GS-nitroxide, JP4-039, is an effective total body irradiation (TBI) mitigator when delivered intravenously (IV) up to 72 h after exposure. Effective systemic and localized administration to oral cavity/oropharynx and esophagus has been demonstrated. The objective of the study was to establish alternatives to IV administration suitable for JP4-039 delivery to mass casualties. JP4-039 was administered to C57BL/6 mice by topically applied carboxy-methyl-cellulose microneedle arrays (MNAs) or by intramuscular (IM) injection. Three different formulations that have passed Food and Drug Administration review, namely Captisol, 2-hydroxypropyl-β-cyclodextrin (cyclodextrin), and Miglyol-812-N, were used for drug delivery. Intraoral (IO) administration with each formulation was also evaluated. All tested formulations and MNAs successfully delivered JP4-039. However, IM delivery of the Miglyol-812-N displayed very efficient and highly reproducible radiation mitigation. Effective IM delivery of JP4-039 in animal models after TBI or partial-body irradiation suggested the use of the Miglyol-812-N formulation in both medical indications and radiation countermeasures.

Acute and Chronic Kidney Injury in a Non-Human Primate Model of Partial-Body Irradiation with Bone Marrow Sparing.

The development of medical countermeasures against acute and delayed multi-organ injury requires animal models predictive of the human response to radiation and its treatment. Late chronic injury is a well-known feature of radiation nephropathy, but acute kidney injury has not been reported in an appropriate animal model. We have established a single-fraction partial-body irradiation model with minimal marrow sparing in non-human primates. Subject-based medical management was used including parenteral fluids according to prospective morbidity criteria. We show herein that 10 or 11 Gy exposures caused both acute and chronic kidney injury. Acute and chronic kidney injury appear to be dose-independent between 10 and 11 Gy. Acute kidney injury was identified during the first 50 days postirradiation and appeared to resolve before the occurrence of chronic kidney injury, which was progressively more severe up to 180 days postirradiation, which was the end of the study. These findings show that mitigation of the acute radiation syndrome by medical management will unmask delayed late effects that occur months after partial-body irradiation. They further emphasize that both acute and chronic changes in kidney function must be taken into account in the use and timing of mitigators and medical management for acute radiation syndrome and delayed effects of acute radiation exposure (DEARE).

A new method for dosimetry standardization using 137Cs biological irradiator based on Fricke solution

Radiobiological experiments such as small animal whole or partial body irradiation, cell culture irradiation, tissue culture irradiation, require accurate and reproducible irradiation dosimetry to allow the work to be interpreted and repeated and for valid comparisons to be made by other laboratories. Limited standardized protocols are available for small animal dosimetry when using 137Cs irradiators.Methods for mapping dose distributions and to determine the regions of isodose such as Gafchromic film, ionization chambers or arrays of Thermoluminescent Dosimeters (TLDs) may result in low-resolution mappings, is very laborious, time-consuming and allows for dosimeter placement inaccuracies in regions of high-dose gradients. Our new approach takes advantage of Fricke solution properties and has been adapted so that it can be performed in 96-well plates. Fricke dosimetry depends on the oxidation of ferrous ions (Fe2+) to ferric ions (Fe3+) by ionizing radiation. The increased concentration of ferric ions is measured spectrophotometrically at 304nm. The Fricke dosimeter is 96% water by weight; therefore, it lends itself well to a determination of absorbed dose to water. This dosimeter is used in a dose range of 5–400Gy and for dose rates of up to 106Gy/s.This new methodology approach allow us to have an absolute dosimetry system, with proven performance, having 96 independent dosimeters on plates of small dimensions. A 3D array of hundreds of independent dosimeters analyzed with a mathematical software to create 3D-surface plots lead that absorbed dose can be estimated in virtually any area of the chamber.Our method could be used for standardization of dosimetry within and between laboratories and for intercomparison programs, which is becoming clear that is needed to be implemented for the radiobiology research procedures.

Protected graft copolymer-formulated fibroblast growth factors mitigate the lethality of partial body irradiation injury.

We evaluated the mitigating effects of fibroblast growth factor 4 and 7 (FGF4 and FGF7, respectively) in comparison with long acting protected graft copolymer (PGC)-formulated FGF4 and 7 (PF4 and PF7, respectively) administered to C57BL/6J mice a day after exposure to LD50/30 (15.7 Gy) partial body irradiation (PBI) which targeted the gastrointestinal (GI) system. The PGC that we developed increased the bioavailability of FGF4 and FGF7 by 5- and 250-fold compared to without PGC, respectively, and also sustained a 24 hr presence in the blood after a single subcutaneous administration. The dose levels tested for mitigating effects on radiation injury were 3 mg/kg for the PF4 and PF7 and 1.5 mg each for their combination (PF4/7). Amifostine administered prior to PBI was used as a positive control. The PF4, PF7, or PF4/7 mitigated the radiation lethality in mice. The mitigating effect of PF4 and PF7 was similar to the positive control and PF7 was better than other mitigators tested. The plasma citrulline levels and hematology parameters were early markers of recovery and survival. GI permeability function appeared to be a late or full recovery indicator. The villus length and crypt number correlated with plasma citrulline level, indicating that it can act as a surrogate marker for these histology evaluations. The IL-18 concentrations in jejunum as early as day 4 and TPO levels in colon on day 10 following PBI showed statistically significant changes in irradiated versus non-irradiated mice which makes them potential biomarkers of radiation exposure. Other colon and jejunum cytokine levels are potentially useful but require larger numbers of samples than in the present study before their full utility can be realized.

Multivariate Analysis of Radiation Responsive Proteins to Predict Radiation Exposure in Total-Body Irradiation and Partial-Body Irradiation Models.

In the event of a radiological or nuclear attack, advanced clinical countermeasures are needed for screening and medical management of the exposed population. In such a scenario, minimally invasive biomarkers that can accurately quantify radiation exposure would be useful for triage management by first responders. In this murine study, we evaluated the efficacy of a novel combination of radiation responsive proteins, Flt3 ligand (FL), serum amyloid A (SAA), matrix metalloproteinase 9 (MMP9), fibrinogen beta (FGB) and pentraxin 3 (PTX3) to predict the received dose after whole- or partial-body irradiation. Ten-week-old female C57BL6 mice received a single whole-body or partial-body dose of 18 Gy from a Pantak X-ray source at a dose rate of 2.28 Gy/min. Plasma was collected by cardiac puncture at 24, 48, 72 h and 1 week postirradiation. Plasma protein levels were determined via commercially available ELISA assay. A multivariate discriminant analysis was utilized to generate best-fit dose prediction models for whole-body exposures using the selected biomarker panel and its potential application to partial-body exposures was examined. The combination of values from FL, SAA, MMP9, FGB and PTX3 between 24 h and 1 week postirradiation yielded novel dose-response relationships. For day 1 postirradiation, the best-fit model yielded a predictive accuracy of 81% utilizing FL alone. The use of additional proteins did not enhance the model accuracy whereas, at day 2 postirradiation, the addition of PTX3 and FGB to FL increased the accuracy to 100%. At day 3 the use of FL and PTX3 yielded a predictive accuracy of 93% and at day 7 use of FL and SAA had an accuracy of 90%. Dose prediction of partial-body exposures based on the TBI model had a higher predictive accuracy when the percentage of the body exposed to radiation increased. Our findings indicate that this novel combination of radiation responsive biomarker proteins are an efficient method for predicting radiation exposure and are more accurate when used in concert compared to using any single biomarker protein alone.

MicroRNA Expression for Early Prediction of Late Occurring Hematologic Acute Radiation Syndrome in Baboons.

For effective medical management of radiation-exposed persons after a radiological/nuclear event, blood-based screening measures in the first few days that could predict hematologic acute radiation syndrome (HARS) are needed. For HARS severity prediction, we used microRNA (miRNA) expression changes measured on days one and two after irradiation in a baboon model. Eighteen baboons underwent different patterns of partial or total body irradiation, corresponding to an equivalent dose of 2.5 or 5 Gy. According to changes in blood cell counts (BCC) the surviving baboons (n = 17) exhibited mild (H1-2, n = 4) or more severe (H2-3, n = 13) HARS. In a two Stage study design we screened 667 miRNAs using a quantitative real-time polymerase chain reaction (qRT-PCR) platform. In Stage II we validated candidates where miRNAs had to show a similar regulation (up- or down-regulated) and a significant 2-fold miRNA expression difference over H0. Seventy-two candidate miRNAs (42 for H1-2 and 30 for H2-3) were forwarded for validation. Forty-two of the H1-2 miRNA candidates from the screening phase entered the validation step and 20 of them showed a statistically significant 2–4 fold up-regulation relative to the unexposed reference (H0). Fifteen of the 30 H2-3 miRNAs were validated in Stage II. All miRNAs appeared 2–3 fold down-regulated over H0 and allowed an almost complete separation of HARS categories; the strongest candidate, miR-342-3p, showed a sustained and 10-fold down-regulation on both days 1 and 2. In summary, our data support the medical decision making of the HARS even within the first two days after exposure where diagnostic tools for early medical decision are required but so far missing. The miRNA species identified and in particular miR-342-3p add to the previously identified mRNAs and complete the portfolio of identified mRNA and miRNA transcripts for HARS prediction and medical management.

Combined Hydration and Antibiotics with Lisinopril to Mitigate Acute and Delayed High-dose Radiation Injuries to Multiple Organs.

The NIAID Radiation and Nuclear Countermeasures Program is developing medical agents to mitigate the acute and delayed effects of radiation that may occur from a radionuclear attack or accident. To date, most such medical countermeasures have been developed for single organ injuries. Angiotensin converting enzyme (ACE) inhibitors have been used to mitigate radiation-induced lung, skin, brain, and renal injuries in rats. ACE inhibitors have also been reported to decrease normal tissue complication in radiation oncology patients. In the current study, the authors have developed a rat partial-body irradiation (leg-out PBI) model with minimal bone marrow sparing (one leg shielded) that results in acute and late injuries to multiple organs. In this model, the ACE inhibitor lisinopril (at ~24 mg m d started orally in the drinking water at 7 d after irradiation and continued to ≥150 d) mitigated late effects in the lungs and kidneys after 12.5-Gy leg-out PBI. Also in this model, a short course of saline hydration and antibiotics mitigated acute radiation syndrome following doses as high as 13 Gy. Combining this supportive care with the lisinopril regimen mitigated overall morbidity for up to 150 d after 13-Gy leg-out PBI. Furthermore, lisinopril was an effective mitigator in the presence of the growth factor G-CSF (100 μg kg d from days 1-14), which is FDA-approved for use in a radionuclear event. In summary, by combining lisinopril (FDA-approved for other indications) with hydration and antibiotics, acute and delayed radiation injuries in multiple organs were mitigated.

Non-targeted transcriptomic effects upon thyroid irradiation: similarity between in-field and out-of-field responses varies with tissue type.

Non-targeted effects can induce responses in tissues that have not been exposed to ionizing radiation. Despite their relevance for risk assessment, few studies have investigated these effects in vivo. In particular, these effects have not been studied in context with thyroid exposure, which can occur e.g. during irradiation of head and neck tumors. To determine the similarity between in-field and out-of-field responses in normal tissue, we used a partial body irradiation setup with female mice where the thyroid region, the thorax and abdomen, or all three regions were irradiated. After 24 h, transcriptional regulation in the kidney cortex, kidney medulla, liver, lungs, spleen, and thyroid was analyzed using microarray technology. Thyroid irradiation resulted in transcriptional regulation in the kidney medulla and liver that resembled regulation upon direct exposure of these tissues regarding both strength of response and associated biological function. The kidney cortex showed fewer similarities between the setups, while the lungs and spleen showed little similarity between in-field and out-of-field responses. Interestingly, effects were generally not found to be additive. Future studies are needed to identify the molecular mechanisms that mediate these systemic effects, so that they may be used as targets to minimize detrimental side effects in radiotherapy.

Novel technique for high-precision stereotactic irradiation of mouse brains.

Small animal irradiation systems were developed for preclinical evaluation of tumor therapy closely resembling the clinical situation. Mostly only clinical LINACs are available, so protocols for small animal partial body irradiation using aconventional clinical system are essential. This study defines aprotocol for conformal brain tumor irradiations in mice. CT and MRI images were used to demarcate the target volume and organs at risk. Three 6MV photon beams were planned for atotal dose of 10fractions of 1.8Gy. The mouse position in adedicated applicator was verified by an X‑ray patient positioning system before each irradiation. Dosimetric verifications (using ionization chambers and films) were performed. Irradiation-induced DNA damage was analyzed to verify the treatment effects on the cellular level. The defined treatment protocol and the applied fractionation scheme were feasible. The in-house developed applicator was suitable for individual positioning at submillimeter accuracy of anesthetized mice during irradiation, altogether performed in less than 10min. All mice tolerated the treatment well. Measured dose values perfectly matched the nominal values from treatment planning. Cellular response was restricted to the target volume. Clinical LINAC-based irradiations of mice offer the potential to treat orthotopic tumors conformably. Especially with respect to lateral penumbra, dedicated small animal irradiation systems exceed the clinical LINAC solution.

Citrulline as a Biomarker for Gastrointestinal-Acute Radiation Syndrome: Species Differences and Experimental Condition Effects.

Animal models of hematopoietic and gastrointestinal acute radiation syndromes (ARS) have been characterized to develop medical countermeasures. Acute radiation-induced decrease of intestinal absorptive function has been correlated to a decrease in the number of intestinal crypt cells resulting from apoptosis and enterocyte mass reduction. Citrulline, a noncoded amino acid, is produced almost exclusively by the enterocytes of the small intestine. Citrullinemia has been identified as a simple, sensitive and suitable biomarker for radiation-induced injury associated with gastrointestinal ARS (GI-ARS). Here we discuss the effect of radiation on plasma citrulline levels in three different species, C57BL/6 mice, Göttingen minipigs and rhesus nonhuman primates (NHPs), measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). The effects of experimental study conditions such as feeding and anesthesia were also examined on plasma citrulline levels in the NHPs. Both the mice and Göttingen minipigs were partial-body irradiated (PBI) with doses from 13-17 Gy and 8-16 Gy, respectively, whereas NHPs were total-body irradiated (TBI) with doses from 6.72-13 Gy. Blood samples were taken at different time points and plasma citrulline levels were measured in the three species at baseline and after irradiation. Basal plasma citrulline concentrations (mean ± SEM) in mice and minipigs were 57.8 ± 2.8 μM and 63.1 ± 2.1 μM, respectively. NHPs showed a basal plasma citrulline concentration of 32.6 ± 0.7 μM, very similar to that of humans (∼40 μM). Plasma citrulline progressively decreased after irradiation, reaching nadir values between day 3.5 and 7. The onset of citrulline recovery was observed earlier at lower radiation doses, while only partial citrulline recovery was noted at higher radiation doses in minipigs and NHPs, complete recovery was noted in mice at all doses. Plasma citrulline levels in NHPs anesthetized with ketamine and acepromazine significantly decreased by 35.5% (P = 0.0017), compared to unanesthetized NHPs. In the postprandial state, citrulline concentrations in NHPs were slightly but significantly decreased by 12.2% (P = 0.0287). These results suggest that plasma citrulline is affected by experimental conditions such as anesthesia and feeding.

Technical Note: Partial body irradiation of mice using a customized PMMA apparatus and a clinical 3D planning/LINAC radiotherapy system.

In vivo radiobiology experiments involving partial body irradiation (PBI) of mice are of major importance because they allow for the evaluation of individual organ tolerance; overcoming current limitations of experiments using lower dose, whole body irradiation. In the current study, the authors characterize and validate an effective and efficient apparatus for multiple animal PBI, directed to the head, thorax, or abdomen of mice. The apparatus is made of polymethylmethacrylate and consists of a rectangular parallelepiped prism (40 cm × 16 cm × 8 cm), in which five holes were drilled to accomodate standard 60 ml syringes, each housing an unanesthetized, fully immobilized mouse. Following CT-scanning and radiotherapy treatment planning, radiation fields were designed to irradiate the head, thorax, or abdomen of the animal. Thermoluminescent dosimeters (TLDs) were used to confirm the treatment planning dosimetry for primary beam and scattered radiation. Mice are efficiently placed into 60 ml syringes and immobilized, without the use of anesthetics. Although partial rotational movement around the longitudinal axis and a minor 2 mm forward/backward movement are permitted, this does not compromise the irradiation of the chosen body area. TLDs confirmed the dose values predicted by the treatment planning dosimetry, both for primary beam and scattered radiation. The customized PMMA apparatus described and validated is cost-effective, convenient to use, and efficient in performing PBI without the use of anesthesia. The developed apparatus permits the isolated irradiation of the mouse head, thorax, and abdomen. Importantly, the apparatus allows the delivery of PBI to five mice, simultaneously, representing an efficient way to effectively expose a large number of animals to PBI through multiple daily fractions, simulating clinical radiotherapy treatment schedules.

Prevention and Mitigation of Radiation‐Induced Colonic Epithelial Barrier Dysfunction by Lysophosphatidic Acid Receptor‐2 Agonists

BackgroundLysophophatidic acid (LPA), a lipid growth factor, regulates secretion, absorption, cell survival and migration in the intestinal epithelium. Altered LPA activity is associated with many gastrointestinal (GI) diseases such as inflammatory bowel disease, colon cancer and GI acute radiation syndrome (GI‐ARS). Disruption of intestinal epithelial tight junctions (TJ) and gut barrier dysfunction is associated with the pathogenesis of many GI diseases. In this study, we evaluated the effect of LPA2 receptor on radiation‐induced disruption of intestinal epithelial barrier by in vivo and in vitro studies.MethodsWT and LPA2−/− mice were subjected to total body irradiation (TBI; 4Gy) or partial body irradiation (PBI‐BM5; 16 Gy). RP‐1, a stable, LPA2‐specific, LPA analog was administered (0.1 mg/kg, s.c.) 30 min prior to TBI or 24 h after PBI‐BM5. For in vitro studies, Caco‐2 and mICC12 cell monolayers were treated with LPA (10 mM) 30 min prior to irradiation (4 Gy). The barrier function was evaluated by measuring transepithelial electrical resistance (TER) and FITC‐inulin flux. TJ integrity was analyzed by immunofluorescence confocal microscopy for occludin, ZO‐1, F‐actin and claudins. Protein thiol oxidation was evaluated by measuring reduced and oxidized protein thiols by fluorescence staining using BODIPY FL‐N‐(2‐aminoethyl)maleimide as a probe. Colonic sections were also stained for Nrf2, the transcription factor responsible for regulation of antioxidant gene expression.ResultsTBI induced redistribution of TJ and AJ proteins from the epithelial junctions disruption in ileum and colon within 2 hours post irradiation (post‐IR), and the damage was sustained at least until 24 hours. TBI‐induced disruption of TJ and AJ was more severe in LPA2 −/− mice. On the other hand, RP‐1 administration in WT mice completely significantly attenuated TBI‐induced TJ and AJ disruption. PBI induced TJ disruption at 48 hours post‐IR, which was sustained at least until 100 hours. RP‐1 administered 24 h after IR mitigated PBI‐induced loss of TJ integrity. Both TBI and PBI depleted reduced protein thiols in colonic epithelium, which was blocked by RP‐1 administration. This effect of RP‐1 was associated with mitigation of PBI‐induced reduction of Nrf2 levels in colonic epithelium. In Caco‐2 and mICC12 cell monolayers, IR reduced TER, elevated inulin permeability and induced redistribution of TJ proteins in Caco‐2 and mICC12 cell monolayers. LPA (10 mM) administration, blocked IR‐induced decrease in TER, increase in inulin permeability and redistribution of TJ proteins.ConclusionThese results indicate that LPA2 receptor agonists prevent and mitigate radiation‐induced colonic epithelial barrier dysfunction. Studies in Caco‐2 and mICC12 cells indicate that LPA agonists may directly impact the intestinal epithelial cells. Supported by NIH grant DK55532

A non-human primate model of radiation-induced cachexia.

Cachexia, or muscle wasting, is a serious health threat to victims of radiological accidents or patients receiving radiotherapy. Here, we propose a non-human primate (NHP) radiation-induced cachexia model based on clinical and molecular pathology findings. NHP exposed to potentially lethal partial-body irradiation developed symptoms of cachexia such as body weight loss in a time- and dose-dependent manner. Severe body weight loss as high as 20–25% was observed which was refractory to nutritional intervention. Radiographic imaging indicated that cachectic NHP lost as much as 50% of skeletal muscle. Histological analysis of muscle tissues showed abnormalities such as presence of central nuclei, inflammation, fatty replacement of skeletal muscle, and muscle fiber degeneration. Biochemical parameters such as hemoglobin and albumin levels decreased after radiation exposure. Levels of FBXO32 (Atrogin-1), ActRIIB and myostatin were significantly changed in the irradiated cachectic NHP compared to the non-irradiated NHP. Our data suggest NHP that have been exposed to high dose radiation manifest cachexia-like symptoms in a time- and dose-dependent manner. This model provides a unique opportunity to study the mechanism of radiation-induced cachexia and will aid in efficacy studies of mitigators of this disease.

Clinically Relevant Doses of Enalapril Mitigate Multiple Organ Radiation Injury.

Angiotensin-converting enzyme inhibitors (ACEi) are effective mitigators of radiation nephropathy. To date, their experimental use has been in fixed-dose regimens. In clinical use, doses of ACEi and other medication may be escalated to achieve greater benefit. We therefore used a rodent model to test the ACEi enalapril as a mitigator of radiation injury in an escalating-dose regimen. Single-fraction partial-body irradiation (PBI) with one hind limb out of the radiation field was used to model accidental or belligerent radiation exposures. PBI doses of 12.5, 12.75 and 13 Gy were used to establish multi-organ injury. One third of the rats underwent PBI alone, and two thirds of the rats had enalapril started five days after PBI at a dose of 30 mg/l in the drinking water. When there was established azotemic renal injury enalapril was escalated to a 60 mg/l dose in half of the animals and then later to a 120 mg/l dose. Irradiated rats on enalapril had significant mitigation of combined pulmonary and renal morbidity and had significantly less azotemia. Dose escalation of enalapril did not significantly improve outcomes compared to fixed-dose enalapril. The current data support use of the ACEi enalapril at a fixed and clinically usable dose to mitigate radiation injury after partial-body radiation exposure.

Cytogenetic Analysis on the Yields of Chromosomal Aberrations Induced by the Scattered Doses of γ-Radiation

The present study is undertaken to know the radiation dose-response of chromosomes in the non-target cells, viz. peripheral blood lymphocytes of cancer patients in a context of partial body irradiation. The genotoxic effect of γ- radiation was studied in Head and Neck Squamous Cell Carcinoma (HNSCC) patients exposed to various cumulative doses of 60Co gamma rays during radiotherapy (RT). These patients (P1 to P10) were irradiated for a period of six weeks with a daily fraction of 2 Gy, consecutively for 5 days in every week. The clastogenic effects of radiation in these patients were analysed on every weekend employing chromosomal aberration (CA) assay. Radiosensitivity of these patients were analysed by employing linear regression analysis of the CAs induced by irradiation. Genetic damage observed in all patients on a weekly basis were recorded and analysed at the individual level in comparison with their own pre-therapy baseline data, employing student’s t-test. Dicentrics, centric rings and chromatid breaks were observed as the major kinds of CAs. The total CAs observed were analyzed using two way ANOVA, showed significant (P<0.001) intra and inter-individual variations of the genotoxic effects. Further, a dose dependent increase of cytogenetic damage was observed in the non-target cells viz. lymphocytes. Further, cytogenetic studies in peripheral lymphocytes following gamma radiotherapy of tumors may help to understand the optimum/precise dose of radiation to be employed for RT, may also be useful to predict dosimetry and the possible secondary tumors in irradiated HNSCC patients.

Radiation Induced Bystander Effect: From &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt; Studies to Clinical Application

In the past 20 years, the classic paradigm in radiobiology recognizing DNA as the main target for the action of radiation has changed. The new paradigm assumes that both targeted and non-targeted effects of radiation determine the final outcome of irradiation. Radiotherapy is one of the main modality treatments of neoplastic diseases with intent to cure, or sometimes to palliate only, thus radiation-induced non-targeted effect, commonly referred to as the radiation-induced bystander effect (RIBE) may have a share in cancer treatment. RIBE is mediated by molecular signaling from radiation targeted cells to their non-irradiated neighbors, and comprises such phenomena as bystander effect, genomic instability, adaptive response and abscopal effect. Whereas first three phenomena may appear both in vitro and in vivo, an abscopal effect is closely related to partial body irradiation and is a systemic effect mediated by immunologic system which synergizes with radiotherapy. From the clinical point of view abscopal effect is particularly interesting due to both its possible valuable contribution to the treatment of metastases, and the potential harmful effects as induction of genetic instability and carcinogenesis. This review summarized the main results of investigations of non-targeted effects coming from in vitro monolayer cultures, 3-dimentional models of tissues, preclinical studies on rodents and clinically observed beneficial abscopal effects with particular emphasis on participation of immunotherapy in the creation of abscopal effects.

Changes of protein glycosylation in the course of radiotherapy

This is the first study of changes in protein glycosylation due to exposure of human subjects to ionizing radiation. Site specific glycosylation patterns of 7 major plasma proteins were analyzed; 171 glycoforms were identified; and the abundance of 99 of these was followed in the course of cancer radiotherapy in 10 individual patients. It was found that glycosylation of plasma proteins does change in response to partial body irradiation (∼60Gy), and the effects last during follow-up; the abundance of some glycoforms changed more than twofold. Both the degree of changes and their time-evolution showed large inter-individual variability.