Natural-history Characterization of a Murine Partial-body Irradiation Model System: Establishment of a Multiple-Parameter Based GI-ARS Severity-Scoring System

The purpose of this investigation was to characterize the natural history of a murine total-abdominal-irradiation exposure model to measure gastrointestinal acute radiation injury. Male CD2F1 mice at 12 to 15 weeks old received total-abdominal irradiation using 4-MV linear accelerator X-rays doses of 0, 11, 13.5, 15, 15.75 and 16.5 Gy (2.75 Gy/min). Daily cage-side (i.e., in the animal housing room) observations of clinical signs and symptoms including body weights on all animals were measured up to 10 days after exposure. Jejunum tissues from cohorts of mice were collected at 1, 3, 7 and 10 days after exposure and radiation injury was assessed by histopathological analyses. Results showed time- and dose-dependent loss of body weight [for example at 7 days: 0.66 (±0.80) % loss for 0 Gy, 6.40 (±0.76) % loss at 11 Gy, 9.43 (±2.06) % loss at 13.5 Gy, 23.53 (± 1.91) % loss at 15 Gy, 29.97 (±1.16) % loss at 15.75 Gy, and 31.79 (±0.76) % loss at 16.5 Gy]. Negligible clinical signs and symptoms, except body weight changes, of radiation injury were observed up to 10 days after irradiation with doses of 11 to 15 Gy. Progressive increases in the severity of clinical signs and symptoms were found after irradiation with doses >15 Gy. Jejunum histology showed a progressive dose-dependent increase in injury. For example, at 7 days postirradiation, the percent of crypts, compared to controls, decreased to 82.3 (±9.5), 69.2 (±12.3), 45.4 (±11.9), 18.0 (±3.4), and 11.5 (± 1.8) with increases in doses from 11 to 16.5 Gy. A mucosal injury scoring system was used that mainly focused on changes in villus morphology damage (i.e., subepithelial spaces near the tips of the villi with capillary congestion, significant epithelial lifting along the length of the villi with a few denuded villus tips). Peak levels of total-abdominal irradiation induced effects on the mucosal injury score were seen 7 days after irradiation for doses ≥15 Gy, with a trend to show a decline after 7 days. A murine multiple-parameter gastrointestinal acute-radiation syndrome severity-scoring system was established based on clinical signs and symptoms that included measures of appearance (i.e., hunched and/or fluffed fur), respiratory rate, general (i.e., decreased mobility) and provoked behavior (i.e., subdued response to stimulation), weight loss, and feces/diarrhea score combined with jejunum mucosal-injury grade score. In summary, the natural-history radio-response for murine partial-body irradiation exposures is important for establishing a well-characterized radiation model system; here we established a multiple-parameter gastrointestinal acute-radiation syndrome severity-scoring system that provides a radiation injury gastrointestinal tissue-based assessment utility.

Optimizing chemical-induced premature chromosome condensation assay for rapid estimation of high-radiation doses

In the event of exposure to high doses of radiation, prompt dose estimation is crucial for selecting appropriate treatment modalities, such as cytokine therapy or stem cell transplantation. The chemical-induced premature chromosome condensation (PCC) method offers a simple approach for such dose estimation with significant radiation exposure, but its 48-h incubation time poses challenges for early dose assessment. In this study, we optimized the chemical-induced PCC assay for more rapid dose assessment. A sufficient number of PCC and G2/M-PCC cells were obtained after 40 h of culture for irradiated human peripheral blood up to 20 Gy. By adding caffeine (final concentration of 1 mM) at 34 h from the start of culture, G2/M-PCC index increased by 1.4-fold in 10 Gy cultures. There was also no significant difference in the G2/M-PCC ring frequency induced for doses 0 to 15 Gy between our 40-h caffeine-supplemented chemical-induced PCC method and the conventional 48-h PCC assay.

Severity scoring systems for radiation-induced GI injury - Prioritization for use of GI-ARS medical countermeasures

PURPOSE

Severity scoring systems for ionizing radiation-induced gastrointestinal injury have been used in animal radiation models, human studies involving the use of radiation therapy, and radiation accidents. Various radiation exposure scenarios (i.e., total body irradiation, total abdominal irradiation, etc.) have been used to investigate ionizing radiation-induced gastrointestinal injury. These radiation-induced GI severity scoring systems are based on clinical signs and symptoms and gastrointestinal-specific biomarkers (i.e., citrulline, etc.). In addition, the time course for radiation-induced changes in blood citrulline levels were compared across various animal (i.e., mice, minipigs, Rhesus Macaque, etc.) and human model systems.

CONCLUSIONS

A worksheet tool was developed to prioritize individuals with severe life-threatening gastrointestinal acute radiation syndrome, based on the design of the Exposure and Symptom Tool addressing hematopoietic acute radiation syndrome, to rescue individuals from potential gastrointestinal acute radiation syndrome injury. This tool provides a triage diagnostic approach to assist first-responders to assess individuals suspected of showing gastrointestinal acute radiation syndrome severity to guide medical management, hence enhancing medical readiness for managing radiological casualties.

Combined radiation injury and its impacts on radiation countermeasures and biodosimetry

PURPOSE

Preparedness for medical responses to major radiation accidents and the increasing threat of nuclear warfare worldwide necessitates an understanding of the complexity of combined radiation injury (CI) and identifying drugs to treat CI is inevitably critical. The vital sign and survival after CI were presented. The molecular mechanisms, such as microRNA pathways, NF-κB-iNOS-IL-18 pathway, C3 production, the AKT-MAPK cross-talk, and TLR/MMP increases, underlying CI in relation to organ injury and mortality were analyzed. At present, no FDA-approved drug to protect, mitigate, or treat CI is available. The development of CI-specific medical countermeasures was reviewed. Because of the worsened acute radiation syndrome resulting from CI, diagnostic triage can be problematic. Therefore, biodosimetry and CI are bundled together with the need to establish effective triage methods with CI.

CONCLUSIONS

CI mouse model studies at AFRRI are reviewed addressing molecular responses, findings from medical countermeasures, and a proposed plasma proteomic biodosimetry approach based on a panel of radiation-responsive biomarkers (i.e., CD27, Flt-3L, GM-CSF, CD45, IL-12, TPO) negligibly influenced by wounding in an algorithm used for dose predictions is described.

Mitotic index maximization with no effect on radiation-induced dicentric chromosome frequency

PURPOSE

The dicentric chromosome (Dic) assay, which is the gold standard for biological dose assessment in radiation emergency medicine, requires an analysis of at least 500 lymphocyte metaphases or 100 Dic aberrations. Therefore, peripheral blood culture conditions able to obtain a high frequency of metaphases for efficient dose evaluation should be optimized. However, the type of blood cultures [i.e. whole blood (WB) or isolated peripheral blood mononuclear cell (PBMC)-culture] and blood volume differ between biodosimetry laboratories. The purpose of this study is to investigate the blood volume at which a high mitotic index (MI) is obtained in peripheral WB-culture and isolated PBMC-culture, and to examine the possible effect of blood volume on radiation-induced Dic frequency.

MATERIALS AND METHODS

Peripheral blood was collected from three healthy donors with their informed consent. The complete and differential blood counts were performed using an automated hematology analyzer. After blood count, peripheral blood was irradiated with 0 or 2 Gy X-ray. Blood was cultured with phytohemagglutinin (180 μg/ml) and demecolcine　(0.05 μg/ml) for 48 h. The MI and Dic frequency were analyzed in 5, 10, 15, 20, 25, and 30% WB-cultures and 0.6, 1.2, 1.8, 2.4, 3.0, 3.6, and 4.2 ml WB-equivalent PBMC-cultures.

RESULTS

In WB-culture, MI showed the highest value (∼22%) in 5-15% WB-culture and then gradually decreased to ∼9% with 30% WB-culture. MI peaked at 36 and 31% in 1.8 and 2.4 ml-WB equivalent volumes for PMBC-cultures, respectively. MI progressively decreased as the amount of PBMCs increased. Although individual differences were observed in the MI values among the three subjects, all the subjects showed the same tendency and higher MI was seen in PBMC than WB-cultures. However, these factors had no significant impact on the yield of Dics. In all culture conditions, the estimated dose calculated based on the Dic frequency was equivalent to the absorbed dose of ex vivo X-ray-irradiated blood.

CONCLUSION

While MI was affected by the blood culture type and the volume of cultured blood, Dic yield did not differ significantly between these conditions. These results could be used by relevant laboratories to optimize MI in certain circumstances.

Early molecular markers for retrospective biodosimetry and prediction of acute health effects

Radiation-induced biological changes occurring within hours and days after irradiation can be potentially used for either exposure reconstruction (retrospective dosimetry) or the prediction of consecutively occurring acute or chronic health effects. The advantage of molecular protein or gene expression (GE) (mRNA) marker lies in their capability for early (1-3 days after irradiation), high-throughput and point-of-care diagnosis, required for the prediction of the acute radiation syndrome (ARS) in radiological or nuclear scenarios. These molecular marker in most cases respond differently regarding exposure characteristics such as e.g. radiation quality, dose, dose rate and most importantly over time. Changes over time are in particular challenging and demand certain strategies to deal with. With this review, we provide an overview and will focus on already identified and used mRNA GE and protein markers of the peripheral blood related to the ARS. These molecules are examined in light of 'ideal' characteristics of a biomarkers (e.g. easy accessible, early response, signal persistency) and the validation degree. Finally, we present strategies on the use of these markers considering challenges as their variation over time and future developments regarding e.g. origin of samples, point of care and high-throughput diagnosis.

Early-response multiple-parameter biodosimetry and dosimetry: risk predictions

The accepted generic multiple-parameter and early-response biodosimetry and dosimetry assessment approach for suspected high-dose radiation (i.e. life-threatening) exposure includes measuring radioactivity associated with the exposed individual (if appropriate); observing and recording prodromal signs/symptoms; obtaining serial complete blood counts with white-blood-cell differential; sampling blood for the chromosome-aberration cytogenetic bioassay using the 'gold standard' dicentric assay (premature chromosome condensation assay for exposures >5 Gy photon acute doses equivalent), measurement of proteomic biomarkers and gene expression assays for dose assessment; bioassay sampling, if appropriate, to determine radioactive internal contamination; physical dose reconstruction, and using other available opportunistic dosimetry approaches. Biodosimetry and dosimetry resources are identified and should be setup in advance along with agreements to access additional national, regional, and international resources. This multifaceted capability needs to be integrated into a biodosimetry/dosimetry 'concept of operations' for use in a radiological emergency. The combined use of traditional biological-, clinical-, and physical-dosimetry should be use in an integrated approach to provide: (a) early-phase diagnostics to guide the development of initial medical-management strategy, and (b) intermediate and definitive assessment of radiation dose and injury. Use of early-phase (a) clinical signs and symptoms, (b) blood chemistry biomarkers, and (c) triage cytogenetics shows diagnostic utility to predict acute radiation injury severity.

RENEB Inter-Laboratory comparison 2017: limits and pitfalls of ILCs

PURPOSE

In case of a mass-casualty radiological event, there would be a need for networking to overcome surge limitations and to quickly obtain homogeneous results (reported aberration frequencies or estimated doses) among biodosimetry laboratories. These results must be consistent within such network. Inter-laboratory comparisons (ILCs) are widely accepted to achieve this homogeneity. At the European level, a great effort has been made to harmonize biological dosimetry laboratories, notably during the MULTIBIODOSE and RENEB projects. In order to continue the harmonization efforts, the RENEB consortium launched this intercomparison which is larger than the RENEB network, as it involves 38 laboratories from 21 countries. In this ILC all steps of the process were monitored, from blood shipment to dose estimation. This exercise also aimed to evaluate the statistical tools used to compare laboratory performance.

MATERIALS AND METHODS

Blood samples were irradiated at three different doses, 1.8, 0.4 and 0 Gy (samples A, C and B) with 4-MV X-rays at 0.5 Gy min^-1, and sent to the participant laboratories. Each laboratory was requested to blindly analyze 500 cells per sample and to report the observed frequency of dicentric chromosomes per metaphase and the corresponding estimated dose.

RESULTS

This ILC demonstrates that blood samples can be successfully distributed among laboratories worldwide to perform biological dosimetry in case of a mass casualty event. Having achieved a substantial harmonization in multiple areas among the RENEB laboratories issues were identified with the available statistical tools, which are not capable to advantageously exploit the richness of results of a large ILCs. Even though Z- and U-tests are accepted methods for biodosimetry ILCs, setting the number of analyzed metaphases to 500 and establishing a tests' common threshold for all studied doses is inappropriate for evaluating laboratory performance. Another problem highlighted by this ILC is the issue of the dose-effect curve diversity. It clearly appears that, despite the initial advantage of including the scoring specificities of each laboratory, the lack of defined criteria for assessing the robustness of each laboratory's curve is a disadvantage for the 'one curve per laboratory' model.

CONCLUSIONS

Based on our study, it seems relevant to develop tools better adapted to the collection and processing of results produced by the participant laboratories. We are confident that, after an initial harmonization phase reached by the RENEB laboratories, a new step toward a better optimization of the laboratory networks in biological dosimetry and associated ILC is on the way.

Celebrating 60 Years of Accomplishments of the Armed Forces Radiobiology Research Institute1

Chartered by the U.S. Congress in 1961, the Armed Forces Radiobiology Research Institute (AFRRI) is a Joint Department of Defense (DoD) entity with the mission of carrying out the Medical Radiological Defense Research Program in support of our military forces around the globe. In the last 60 years, the investigators at AFRRI have conducted exploratory and developmental research with broad application to the field of radiation sciences. As the only DoD facility dedicated to radiation research, AFRRI's Medical Radiobiology Advisory Team provides deployable medical and radiobiological subject matter expertise, advising commanders in the response to a U.S. nuclear weapon incident and other nuclear or radiological material incidents. AFRRI received the DoD Joint Meritorious Unit Award on February 17, 2004, for its exceptionally meritorious achievements from September 11, 2001 to June 20, 2003, in response to acts of terrorism and nuclear/radiological threats at home and abroad. In August 2009, the American Nuclear Society designated the institute a nuclear historic landmark as the U.S.'s primary source of medical nuclear and radiological research, preparedness and training. Since then, research has continued, and core areas of study include prevention, assessment and treatment of radiological injuries that may occur from exposure to a wide range of doses (low to high). AFRRI collaborates with other government entities, academic institutions, civilian laboratories and other countries to research the biological effects of ionizing radiation. Notable early research contributions were the establishment of dose limits for major acute radiation syndromes in primates, applicable to human exposures, followed by the subsequent evolution of radiobiology concepts, particularly the importance of immune collapse and combined injury. In this century, the program has been essential in the development and validation of prophylactic and therapeutic drugs, such as Amifostine, Neupogen®, Neulasta®, Nplate® and Leukine®, all of which are used to prevent and treat radiation injuries. Moreover, AFRRI has helped develop rapid, high-precision, biodosimetry tools ranging from novel assays to software decision support. New drug candidates and biological dose assessment technologies are currently being developed. Such efforts are supported by unique and unmatched radiation sources and generators that allow for comprehensive analyses across the various types and qualities of radiation. These include but are not limited to both 60Co facilities, a TRIGA® reactor providing variable mixed neutron and γ-ray fields, a clinical linear accelerator, and a small animal radiation research platform with low-energy photons. There are five major research areas at AFRRI that encompass the prevention, assessment and treatment of injuries resulting from the effects of ionizing radiation: 1. biodosimetry; 2. low-level and low-dose-rate radiation; 3. internal contamination and metal toxicity; 4. radiation combined injury; and 5. radiation medical countermeasures. These research areas are bolstered by an educational component to broadcast and increase awareness of the medical effects of ionizing radiation, in the mass-casualty scenario after a nuclear detonation or radiological accidents. This work provides a description of the military medical operations as well as the radiation facilities and capabilities present at AFRRI, followed by a review and discussion of each of the research areas.

Improved harvest and fixation methodology for isolated human peripheral blood mononuclear cells in cytokinesis-block micronucleus assay

PURPOSE

In suspected radiation exposures, cytokinesis-block micronucleus (CBMN) assay is used for biodosimetry by detecting micronuclei (MN) in binucleated (BN) cells in whole blood and isolated peripheral blood mononuclear cell (PBMC) cultures. Standardized harvest protocols for whole blood were published by the International Atomic Energy Agency (IAEA) in 2001 (Technical report no. 405) and 2011 (EPR-Biodosimetry). For isolated PBMC harvest, cytocentrifugation of fresh cells is recommended to preserve cytoplasmic boundaries for MN scoring. However, cytocentrifugation utilizes specialized equipment and long-term cell suspension storage is difficult. In this study, an alternative CBMN harvest protocol is proposed for laboratories interested in culturing PBMCs and storing fixed cells with routine biodosimetry methods.

MATERIALS AND METHODS

Peripheral blood from 4 males (24, 34, 41, 51 y.o.) and females (26, 37, 44, 56 y.o.) was irradiated with 0 and 2 Gy X-rays. For cells harvested with IAEA 2001 and 2011 protocols, whole blood was used. For cells harvested with our protocol (CRG), isolated PBMCs were used. CRG protocol was validated in DAPI, acridine orange and Giemsa stain, and in three other laboratories. Cytoplasm status, nuclear division index (NDI) and induced MN frequency (MN frequency at 2 Gy - background MN frequency at 0 Gy) (MN/1000 BN) of Giemsa-stained BN cells were compared in IAEA 2001, IAEA 2011, IAEA 2011 + formaldehyde (FA) and CRG protocols. Effects of low and high humidity spreading were evaluated.

RESULTS

>94% of 1000 BN cells were scorable with clear cytoplasmic boundaries in all donors harvested with CRG protocol. FA addition in IAEA 2011 protocol reduced cell rupture in whole blood cultures, but cell rupture was affected by age, sex and humidity. Almost all cells harvested with IAEA 2001 protocol had cytoplasm loss. PBMCs harvested with CRG protocol stained well in DAPI, acridine orange and Giemsa, and showed high scorable BN frequency in all laboratories. A higher NDI and a lower induced MN frequency were seen in 2 Gy isolated PBMC than whole blood cultures.

CONCLUSION

This quick CBMN harvest protocol for isolated PBMCs is a viable alternative to cytocentrifugation, as many scorable BN cells were obtained with routine biodosimetry reagents and equipment. IAEA 2011 + FA protocol should be used to improve CBMN harvest in whole blood cultures. Humidity during spreading should be optimized depending on the harvest protocol. NDI and MN frequency should be separately evaluated for whole blood and isolated PBMC cultures.

Automated Dicentric Aberration Scoring for Triage Dose Assessment: 60Co Gamma Ray Dose-response at Different Dose Rates

The objective of this study was to establish radiation dose-response calibration curves using automated dicentric scoring to support rapid and accurate cytogenetic triage dose-assessment. Blood was drawn from healthy human volunteers and exposed to Co gamma rays at several dose rates (i.e., 1.0, 0.6, and 0.1 Gy min). After radiation, the blood was placed for 2 h in a 37 °C incubator for repair. Blood was then cultured in complete media to which a mitogen (i.e., phytoghemagglutinin, concentration 4%) was added for 48 h. Colcemid was added to the culture at a final concentration of 0.2 μg mL after 24 h for the purpose of arresting first-division metaphase mitotics. Cells were harvested at the end of 48 h. Samples were processed using an automated metaphase harvester and automated microscope metaphase finder equipped with a suite of software including a specialized automated dicentric scoring application. The data obtained were used to create dose-response tables of dicentric yields. The null hypothesis that the data is Poisson-distributed could not be rejected at the significance level of α = 0.05 using results from a Shiny R Studio application (goodness-of-fit Poisson). Calibration curves based on linear-quadratic fits for Co gamma rays at the three different dose rates were generated using these data. The calibration curves were used to detect blind test cases. In conclusion, using the automated harvester and automated microscope metaphase finder with associated automated dicentric scoring software demonstrates high-throughput with suitable accuracy for triage radiation dose assessment.

CONCEPTS OF OPERATIONS FOR A US DOSIMETRY AND BIODOSIMETRY NETWORK

The USA must be prepared to provide a prompt, coordinated and integrated response for radiation dose and injury assessment for suspected radiation exposure, whether it involves isolated cases or mass casualties. Dose estimation for radiation accidents typically necessitates a multiple parameter diagnostics approach that includes clinical, biological and physical dosimetry to provide an early-phase radiation dose. A US Individual Dosimetry and Biodosimetry Network (US-IDBN) will increase surge capacity for civilian and military populations in a large-scale incident. The network's goal is to leverage available resources and provide an integrated biodosimetry capability, using multiple parameter diagnostics. Initial operations will be to expand an existing functional integration of two cytogenetic biodosimetry laboratories by developing Standard Operating Procedures, cross-training laboratorians, developing common calibration curves, supporting inter-comparison exercises and obtaining certification to process clinical samples. Integration with certified commercial laboratories will increase surge capacity to meet the needs of a mass-casualty incident.

BABOON RADIATION QUALITY (MIXED-FIELD NEUTRON AND GAMMA, GAMMA ALONE) DOSE-RESPONSE MODEL SYSTEMS: ASSESSMENT OF H-ARS SEVERITY USING HAEMATOLOGIC BIOMARKERS

Results from archived (1986 and 1996) experiments were used to establish a baboon radiation-quality dose-response database with haematology biomarker time-course data following exposure to mixed-fields (i.e. neutron to gamma ratio: 5.5; dose: 0-8 Gy) and 60Co gamma-ray exposures (0-15 Gy). Time-course (i.e. 0-40 d) haematology changes for relevant blood-cell types for both mixed-field (neutron to gamma ratio = 5.5) and gamma ray alone were compared and models developed that showed significant differences using the maximum likehood ratio test. A consensus METREPOL-like haematology ARS (H-ARS) severity scoring system for baboons was established using these results. The data for mixed-field and the gamma only cohorts appeared similar, and so the cohorts were pooled into a single consensus H-ARS severity scoring system. These findings provide proof-of-concept for the use of a METREPOL H-ARS severity scoring system following mixed-field and gamma exposures.

System for Scoring Severity of Acute Radiation Syndrome Response in Rhesus Macaques (Macaca mulatta)

We developed a clinical assessment tool for use in an NHP radiation model to 1) quantify severity responses for subsyndromes of the acute radiation syndrome (ARS; that is, hematopoietic and others) and 2) identify animals that required enhanced monitoring. Our assessment tool was based primarily on the MEdical TREatment ProtocOLs for Radiation Accident Victims (METREPOL) scoring system but was adapted for NHP to include additional indices (for example, behaviors) for use in NHP studies involving limited medical intervention. Male (n = 16) and female (n = 12) rhesus macaques (Macaca mulatta; 5 groups: sham and 1.0, 3.5, 6.5, and 8.5 Gy; n = 6 per group) received sham- or bilateral 60Co γ-irradiation at approximately 0.6 Gy/mn. Clinical signs of ARS and blood analysis were obtained before and serially for clinical assessment during the period of 6 h to 60 d after sham or 60Co irradiation. Minimal supportive care (that is, supplemental nutrition, subcutaneous fluid, loperamide, acetaminophen, and topical antibiotic ointment) was prescribed based on clinical observations. Results from clinical signs and assays for assessment of relevant organ systems in individual animals were stratified into ARS severity scores of normal (0), mild (1), moderate (2), and severe (3 or 4). Individual NHP were scored for maximal subsyndrome ARS severity in multiple organ systems by using the proposed ARS scoring system to obtain an overall ARS response category. One NHP died unexpectedly. The multiple-parameter ARS severity scoring tool aided in the identification of animals in the high-dose (6.5 and 8.5 Gy) groups that required enhanced monitoring.

Use of Proteomic and Hematology Biomarkers for Prediction of Hematopoietic Acute Radiation Syndrome Severity in Baboon Radiation Models

Use of plasma proteomic and hematological biomarkers represents a promising approach to provide useful diagnostic information for assessment of the severity of hematopoietic acute radiation syndrome. Eighteen baboons were evaluated in a radiation model that underwent total-body and partial-body irradiations at doses of Co gamma rays from 2.5 to 15 Gy at dose rates of 6.25 cGy min and 32 cGy min. Hematopoietic acute radiation syndrome severity levels determined by an analysis of blood count changes measured up to 60 d after irradiation were used to gauge overall hematopoietic acute radiation syndrome severity classifications. A panel of protein biomarkers was measured on plasma samples collected at 0 to 28 d after exposure using electrochemiluminescence-detection technology. The database was split into two distinct groups (i.e., "calibration," n = 11; "validation," n = 7). The calibration database was used in an initial stepwise regression multivariate model-fitting approach followed by down selection of biomarkers for identification of subpanels of hematopoietic acute radiation syndrome-responsive biomarkers for three time windows (i.e., 0-2 d, 2-7 d, 7-28 d). Model 1 (0-2 d) includes log C-reactive protein (p < 0.0001), log interleukin-13 (p < 0.0054), and procalcitonin (p < 0.0316) biomarkers; model 2 (2-7 d) includes log CD27 (p < 0.0001), log FMS-related tyrosine kinase 3 ligand (p < 0.0001), log serum amyloid A (p < 0.0007), and log interleukin-6 (p < 0.0002); and model 3 (7-28 d) includes log CD27 (p < 0.0012), log serum amyloid A (p < 0.0002), log erythropoietin (p < 0.0001), and log CD177 (p < 0.0001). The predicted risk of radiation injury categorization values, representing the hematopoietic acute radiation syndrome severity outcome for the three models, produced least squares multiple regression fit confidences of R = 0.73, 0.82, and 0.75, respectively. The resultant algorithms support the proof of concept that plasma proteomic biomarkers can supplement clinical signs and symptoms to assess hematopoietic acute radiation syndrome risk severity.

MODELING H-ARS USING HEMATOLOGICAL PARAMETERS: A COMPARISON BETWEEN THE NON-HUMAN PRIMATE AND MINIPIG

Multiple hematological biomarkers (i.e. complete blood counts and serum chemistry parameters) were used in a multivariate linear-regression fit to create predictive algorithms for estimating the severity of hematopoietic acute radiation syndrome (H-ARS) using two different species (i.e. Göttingen Minipig and non-human primate (NHP) (Macacca mulatta)). Biomarker data were analyzed prior to irradiation and between 1-60 days (minipig) and 1-30 days (NHP) after irradiation exposures of 1.6-3.5 Gy (minipig) and 6.5 Gy (NHP) ⁶⁰Co gamma ray doses at 0.5-0.6 Gy min^-1 and 0.4 Gy min^-1, respectively. Fitted radiation risk and injury categorization (RRIC) values and RRIC prediction percent accuracies were compared between the two models. Both models estimated H-ARS severity with over 80% overall predictive power and with receiver operating characteristic curve area values of 0.884 and 0.825. These results based on two animal radiation models support the concept for the use of a hematopoietic-based algorithm for predicting the risk of H-ARS in humans.

Non-human Primate Total-body Irradiation Model with Limited and Full Medical Supportive Care Including Filgrastim for Biodosimetry and Injury Assessment

An assessment of multiple biomarkers from radiation casualties undergoing limited- or full-supportive care including treatment with filgrastim is critical to develop rapid and effective diagnostic triage strategies. The efficacy of filgrastim with full-supportive care was compared with results with limited-supportive care by analyzing survival, necropsy, histopathology and serial blood samples for hematological, serum chemistry and protein profiles in a non-human primate (Macaca mulatta, male and female) model during 60-d post-monitoring period following sham- and total-body irradiation with 6.5 Gy ⁶⁰Co gamma-rays at 0.6 Gy min^-1 Filgrastim (10 μg kg^-1) was administered beginning on Day 1 post-exposure and continued daily until neutrophil counts were ≥2,000 μL^-1 for two consecutive days. Filgrastim and full-supportive care significantly decreased the pancytopenia duration and resulted in improved animal survival and recovery compared to animals with a limited-supportive care. These findings also identified and validated a multiparametric biomarker panel to support radiation diagnostic device development.

U.S. Department of Defense Multiple-Parameter Biodosimetry Network

The U.S. Department of Defense (USDOD) service members are at risk of exposure to ionizing radiation due to radiation accidents, terrorist attacks and national defense activities. The use of biodosimetry is a standard of care for the triage and treatment of radiation injuries. Resources and procedures need to be established to implement a multiple-parameter biodosimetry system coupled with expert medial guidance to provide an integrated radiation diagnostic system to meet USDOD requirements. Current USDOD biodosimetry capabilities were identified and recommendations to fill the identified gaps are provided. A USDOD Multi-parametric Biodosimetry Network, based on the expertise that resides at the Armed Forces Radiobiology Research Institute and the Naval Dosimetry Center, was designed. This network based on the use of multiple biodosimetry modalities would provide diagnostic and triage capabilities needed to meet USDOD requirements. These are not available with sufficient capacity elsewhere but could be needed urgently after a major radiological/nuclear event.

Concepts of Operations (CONOPS) for Biodosimetry Tools Employed in Operational Environments

It is essential to identify improved capabilities to accurately identify, confirm, and/or quantify radiological exposure and injury in order to inform critical triage, diagnosis, and treatment decisions. Herein the authors report characteristic requirements and potential Concepts of Operations (CONOPS) for biodosimetry tools employed in operational environments. While similar significant efforts have been completed in this area for the U.S. civilian sector, limited perspectives are published in the peer-reviewed literature regarding the use of radiological diagnostic technologies in deployed military medical treatment settings. Two radiological exposure scenarios were developed to clarify the diagnostic performance criteria and identify capability gaps. The emerging technology areas associated with radiation exposure diagnostics were reviewed and assessed to gauge their suitability in supporting triage, treatment, and return to duty decisions within the military medical support system.

HEMODOSE: A Biodosimetry Tool Based on Multi-type Blood Cell Counts

Peripheral blood cell counts are important biomarkers of radiation exposure. In this work, a simplified compartmental modeling approach is applied to simulate the perturbation of the hematopoiesis system in humans after radiation exposure, and HemoDose software is reported to estimate individuals' absorbed doses based on multi-type blood cell counts. Testing with patient data in some historical accidents indicates that either single or serial granulocyte, lymphocyte, leukocyte, and platelet counts after exposure can be robust indicators of the absorbed doses. In addition, such correlation exists not only in the early time window (1 or 2 d) but also in the late phase (up to 4 wk) after exposure, when the four types of cell counts are combined for analysis. These demonstrate the capability of HemoDose as a rapid point-of-care diagnostic or centralized high-throughput assay system for personnel exposed to unintended high doses of radiation, especially in large-scale nuclear/radiological disaster scenarios involving mass casualties.

Significant disparity in base and sugar damage in DNA resulting from neutron and electron irradiation

In this study, a comparison of the effects of neutron and electron irradiation of aqueous DNA solutions was investigated to characterize potential neutron signatures in DNA damage induction. Ionizing radiation generates numerous lesions in DNA, including base and sugar lesions, lesions involving base-sugar combinations (e.g. 8,5'-cyclopurine-2'-deoxynucleosides) and DNA-protein cross-links, as well as single- and double-strand breaks and clustered damage. The characteristics of damage depend on the linear energy transfer (LET) of the incident radiation. Here we investigated DNA damage using aqueous DNA solutions in 10 mmol/l phosphate buffer from 0-80 Gy by low-LET electrons (10 Gy/min) and the specific high-LET (∼0.16 Gy/h) neutrons formed by spontaneous (252)Cf decay fissions. 8-hydroxy-2'-deoxyguanosine (8-OH-dG), (5'R)-8,5'-cyclo-2'-deoxyadenosine (R-cdA) and (5'S)-8,5'-cyclo-2'-deoxyadenosine (S-cdA) were quantified using liquid chromatography-isotope-dilution tandem mass spectrometry to demonstrate a linear dose dependence for induction of 8-OH-dG by both types of radiation, although neutron irradiation was ∼50% less effective at a given dose compared with electron irradiation. Electron irradiation resulted in an exponential increase in S-cdA and R-cdA with dose, whereas neutron irradiation induced substantially less damage and the amount of damage increased only gradually with dose. Addition of 30 mmol/l 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), a free radical scavenger, to the DNA solution before irradiation reduced lesion induction to background levels for both types of radiation. These results provide insight into the mechanisms of DNA damage by high-LET (252)Cf decay neutrons and low-LET electrons, leading to enhanced understanding of the potential biological effects of these types of irradiation.

A novel parameter, cell-cycle progression index, for radiation dose absorbed estimation in the premature chromosome condensation assay

The calyculin A-induced premature chromosome condensation (PCC) assay is a simple and useful method for assessing the cell-cycle distribution in cells, since calyculin A induces chromosome condensation in various phases of the cell cycle. In this study, a novel parameter, the cell-cycle progression index (CPI), in the PCC assay was validated as a novel biomarker for biodosimetry. Peripheral blood was drawn from healthy donors after informed consent was obtained. CPI was investigated using a human peripheral blood lymphocyte (PBL) ex vivo irradiation ((60)Co-gamma rays: ∼0.6 Gy min(-1), or X ray: 1.0 Gy min(-1); 0-10 Gy) model. The calyculin A-induced PCC assay was performed for chromosome preparation. PCC cells were divided into the following five categories according to cell-cycle stage: non-PCC, G1-PCC, S-PCC, G2/M-PCC and M/A-PCC cells. CPI was calculated as the ratio of G2/M-PCC cells to G1-PCC cells. The PCC-stage distribution varied markedly with irradiation doses. The G1-PCC cell fraction was significantly reduced, and the G2/M-PCC cell fraction increased, in 10-Gy-irradiated PBL after 48 h of culture. CPI levels were fitted to an exponential dose-response curve with gamma-ray irradiation [y = 0.6729 + 0.3934 exp(0.5685D), r = 1.0000, p < 0.0001] and X-ray irradiation [y = -0.3743 + 0.9744 exp(0.3321D), r = 0.9999, p < 0.0001]. There were no significant individual (p = 0.853) or gender effects (p = 0.951) on the CPI in the human peripheral blood ex vivo irradiation model. Furthermore, CPI measurements are rapid (< 15 min per case). These results suggest that the CPI is a useful screening tool for the assessment of radiation doses received ranging from 0 to 10 Gy in radiation exposure early after a radiation event, especially after a mass-casualty radiological incident.

Further biodosimetry investigations using murine partial-body irradiation model

This study evaluates both the effects of physical restraint and use of candidate biomarkers in a CD2F1 male mouse partial-body irradiation model for biological dosimetry diagnostic assays. Mice were irradiated (6-Gy, 250-kVp X ray) to 3/3rd (total body), 2/3rd (gut and torso), 1/3rd (gut only) and 0/3rd (sham) of total body. Blood was sampled for haematology and blood plasma proteomic biomarkers at 1 and 2 d after exposure. Increases in the body fraction exposed showed progressive decreases in lymphocyte counts and increases in the neutrophil-to-lymphocyte ratios with no significant differences in the neutrophil and platelet counts. The radioresponse for plasma biomarker Flt3L showed proportional increases; however, G-CSF and SAA levels exhibited dramatic and non-proportional increases in levels. Physical restraint at 1 d post-exposure increased lymphocyte counts and SAA, decreased neutrophil-to-lymphocyte ratio and Flt3L and showed no effects on neutrophil and platelet counts or G-CSF.

Protein biomarkers for enhancement of radiation dose and injury assessment in nonhuman primate total-body irradiation model

Development and validation of early-response radiation injury biomarkers are critical for effective triage and medical management of irradiated individuals. Plasma protein and haematological profiles were evaluated using multivariate linear-regression analysis to provide dose-response calibration curves for photon-radiation dose assessment in 30 rhesus macaques total-body-irradiated to 1-8.5 Gy with (60)Co gamma rays (0.55 Gy min(-1)). Equations for radiation dose received were established based on different combinations of protein biomarkers [i.e. C-reactive protein (CRP), serum amyloid A (SAA), interleukin 6 (IL-6) and Flt3 Ligand (Flt3L)] at samples collection time-points 6 h, 1, 2, 3, 4 and 7 d post-total-body irradiation. Dynamic changes in the levels of CRP, SAA, IL-6 and Flt3L may function as prognostic indicators of the time course and severity of acute radiation sickness (ARS). The combination of protein biomarkers provides greater accuracy for early radiation assessment than any one biomarker alone.

DNA repair and cell cycle biomarkers of radiation exposure and inflammation stress in human blood

DNA damage and repair are hallmarks of cellular responses to ionizing radiation. We hypothesized that monitoring the expression of DNA repair-associated genes would enhance the detection of individuals exposed to radiation versus other forms of physiological stress. We employed the human blood ex vivo radiation model to investigate the expression responses of DNA repair genes in repeated blood samples from healthy, non-smoking men and women exposed to 2 Gy of X-rays in the context of inflammation stress mimicked by the bacterial endotoxin lipopolysaccharide (LPS). Radiation exposure significantly modulated the transcript expression of 12 genes of 40 tested (2.2E-06<p<0.03), of which 8 showed no overlap between unirradiated and irradiated samples (CDKN1A, FDXR, BBC3, PCNA, GADD45a, XPC, POLH and DDB2). This panel demonstrated excellent dose response discrimination (0.5 to 8 Gy) in an independent human blood ex vivo dataset, and 100% accuracy for discriminating patients who received total body radiation. Three genes of this panel (CDKN1A, FDXR and BBC3) were also highly sensitive to LPS treatment in the absence of radiation exposure, and LPS co-treatment significantly affected their radiation responses. At the protein level, BAX and pCHK2-thr68 were elevated after radiation exposure, but the pCHK2-thr68 response was significantly decreased in the presence of LPS. Our combined panel yields an estimated 4-group accuracy of ∼90% to discriminate between radiation alone, inflammation alone, or combined exposures. Our findings suggest that DNA repair gene expression may be helpful to identify biodosimeters of exposure to radiation, especially within high-complexity exposure scenarios.

Radiation metabolomics. 5. Identification of urinary biomarkers of ionizing radiation exposure in nonhuman primates by mass spectrometry-based metabolomics

Mass spectrometry-based metabolomics has previously demonstrated utility for identifying biomarkers of ionizing radiation exposure in cellular, mouse and rat in vivo radiation models. To provide a valuable link from small laboratory rodents to humans, γ-radiation-induced urinary biomarkers were investigated using a nonhuman primate total-body-irradiation model. Mass spectrometry-based metabolomics approaches were applied to determine whether biomarkers could be identified, as well as the previously discovered rodent biomarkers of γ radiation. Ultra-performance liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry analysis was carried out on a time course of clean-catch urine samples collected from nonhuman primates (n = 6 per cohort) exposed to sham, 1.0, 3.5, 6.5 or 8.5 Gy doses of (60)Co γ ray (∼0.55 Gy/min) ionizing radiation. By multivariate data analysis, 13 biomarkers of radiation were discovered: N-acetyltaurine, isethionic acid, taurine, xanthine, hypoxanthine, uric acid, creatine, creatinine, tyrosol sulfate, 3-hydroxytyrosol sulfate, tyramine sulfate, N-acetylserotonin sulfate, and adipic acid. N-Acetyltaurine, isethionic acid, and taurine had previously been identified in rats, and taurine and xanthine in mice after ionizing radiation exposure. Mass spectrometry-based metabolomics has thus successfully revealed and verified urinary biomarkers of ionizing radiation exposure in the nonhuman primate for the first time, which indicates possible mechanisms for ionizing radiation injury.

Q(γ-H2AX), an analysis method for partial-body radiation exposure using γ-H2AX in nonhuman primate lymphocytes

We previously used the γ-H2AX assay as a biodosimeter for total-body-irradiation (TBI) exposure (γ-rays) in a rhesus macaque (Macaca mulatta) model. Utilizing peripheral blood lymphocytes and plucked hairs, we obtained statistically significant γ-H2AX responses days after total-body exposure to 1-8.5 Gy ((60)Co γ-rays at 55 cGy min(-1)). Here, we introduce a partial-body exposure analysis method, Q(γ-H2AX), which is based on the number of γ-H2AX foci per damaged cells as evident by having one or more γ-H2AX foci per cell. Results from the rhesus monkey - TBI study were used to establish Q(γ-H2AX) dose-response calibration curves to assess acute partial-body exposures. γ-H2AX foci were detected in plucked hairs for several days after in vivo irradiation demonstrating this assay's utility for dose assessment in various body regions. The quantitation of γ-H2AX may provide a robust biodosimeter for analyzing partial body exposures to ionizing radiation in humans.

The use of gamma-H2AX as a biodosimeter for total-body radiation exposure in non-human primates

Background

There is a crucial shortage of methods capable of determining the extent of accidental exposures of human beings to ionizing radiation. However, knowledge of individual exposures is essential for early triage during radiological incidents to provide optimum possible life-sparing medical procedures to each person.

Methods and Findings

We evaluated immunocytofluorescence-based quantitation of γ-H2AX foci as a biodosimeter of total-body radiation exposure (⁶⁰Co γ-rays) in a rhesus macaque (Macaca mulatta) model. Peripheral blood lymphocytes and plucked hairs were collected from 4 cohorts of macaques receiving total body irradiation doses ranging from 1 Gy to 8.5 Gy. Each cohort consisted of 6 experimental and 2 control animals. Numbers of residual γ-H2AX foci were proportional to initial irradiation doses and statistically significant responses were obtained until 1 day after 1 Gy, 4 days after 3.5 and 6.5 Gy, and 14 days after 8.5 Gy in lymphocytes and until 1 day after 1 Gy, at least 2 days after 3.5 and 6.5 Gy, and 9 days after 8.5 Gy in plucked hairs.

Conclusion

These findings indicate that quantitation of γ-H2AX foci may make a robust biodosimeter for analyzing total-body exposure to ionizing radiation in humans. This tool would help clinicians prescribe appropriate types of medical intervention for optimal individual outcome. These results also demonstrate that the use of a high throughput γ-H2AX biodosimeter would be useful for days post-exposure in applications like large-scale radiological events or radiation therapy. In addition, this study validates a possibility to use plucked hair in future clinical trials investigating genotoxic effects of drugs and radiation treatments.

Biodosimetry medical recording-use of the Biodosimetry Assessment Tool

Effective and dynamic recording of radiation exposure and medical diagnostic information for individuals suspected or known to have been exposed to ionizing radiation contributes to appropriate formulation of medical treatment strategies and radiation protection management. The objectives of this article are to report the database entry templates or screens, provide general use guidelines, and discuss the application to selected radiation exposure scenarios for the Armed Forces Radiobiology Research Institute's software application, Biodosimetry Assessment Tool (BAT). BAT data entry screens were developed based on consensus generic guidance and organized into discrete categories (i.e., physical dosimetry, contamination, prodromal symptoms, hematology, lymphocyte cytogenetics, erythema/wound, and infection) to facilitate its practical use during the early-phase response for radiological incidents. The summary report provides a concise output of information on radiation exposure, radionuclide contamination, dose assessment based on biological indicators (i.e., cytogenetic chromosome aberration bioassays, time to onset of vomiting, lymphocyte cell counts or depletion kinetics), and relevant clinical signs and symptoms. The BAT report template is compliant with NATO and international guidance for recording ionizing radiation exposures for medical purposes.

Biodosimetry Assessment Tool (BAT) software-dose prediction algorithms

PURPOSE

Medical management of suspected radiation casualties requires use of multiparameter biodosimetry because no single biodosimetric measurement is sufficiently robust. This report describes the design and algorithms used in a radiation exposure assessment software application that serves as a diagnostic utility for triage and medical treatment formulation, as well as to convey psychological reassurance, for early-phase assessment of radiation exposures, and for surge response assessment for mass radiological casualties.

METHODS

The Armed Forces Radiobiology Research Institute's Biological Dosimetry Research Program developed the integrated multiparameter Biodosimetry Assessment Tool computer program using Microsoft Visual Basic 6 with various second party plug-ins and add-ons. Dose-predicting algorithms were adopted by analyzing data from merged databases of human radiation exposure incidents and normal controls (non-irradiated) volunteers. The results are summarized in user-friendly screens.

SUMMARY

BAT algorithms are presented and compared to other previously published dose assessment algorithms based on biological indicators (i.e., onset of vomiting, lymphocyte depletion kinetics). These new algorithms are incorporated into a computer-based program that assists responders and medical providers in recording relevant diagnostic information and assessing significant radiation exposures. It promotes early-phase (<10 d) data collection after a radiation exposure incident and provides data templates for entry of diagnostic information using multiparameter indices. It allows for recording of relevant clinical information and summarizes diagnostic information such as estimated multiparameter doses. Data can be printed and archived in accordance with civilian and military guidelines.

Multiple parameter radiation injury assessment using a nonhuman primate radiation model-biodosimetry applications

There are urgent needs to establish capability to rapidly assess radiation injury in mass casualty and population monitoring scenarios. This study's objective was to evaluate several currently available biomarkers that can provide early diagnostic triage information after radiation exposure. Hematology and blood chemistry measurements were performed on samples derived from a nonhuman primate (Macaca mulatta; n = 8) total-body irradiation (TBI) model (6.5-Gy Co gamma rays at 0.6 Gy min). The results from this study demonstrate: a) time course for changes in C-reactive protein (CRP) (-2 d to 15 d after TBI); b) time-dependent (-2 d, 1-4 d after TBI) changes in blood cell counts [i.e., lymphocytes decrease to 5-8% of pre-study levels at 1 to 4 d after TBI; ratio of neutrophil to lymphocytes increases by 44 +/- 18 (p = 0.016), 12 +/- 4 (p = 0.001), 8 +/- 2 (p = 0.0020), and 5.0 +/- 2 (p = 0.002) fold at 1, 2, 3, and 4 days after TBI, respectively]; and c) 4.5 +/- 0.8 (p = 0.002)-fold increases in serum amylase activity 1 d after TBI. Plasma CRP levels at 1 d after exposure were 22 +/- 13 (p = 0.0005) (females) and 44 +/- 11 (p = 0.0004) (males)-fold elevated above baseline levels. One hundred percent successful separation of samples from exposed macaques (24 h after TBI) vs. samples from the same macaque taken before irradiation using a discriminant analysis based on four biomarkers (i.e., lymphocytes, neutrophils, ratio of neutrophils to lymphocytes, and serum amylase activity) was demonstrated. These results demonstrate the practical use of multiple parameter biomarkers to enhance the discrimination of exposed vs. non-exposed individuals and justify a follow-on rhesus macaque dose-response study.

Synopsis of partial-body radiation diagnostic biomarkers and medical management of radiation injury workshop

Radiation exposures from accidents, nuclear detonations or terrorist incidents are unlikely to be homogeneous; however, current biodosimetric approaches are developed and validated primarily in whole-body irradiation models. A workshop was held at the Armed Forces Radiobiology Research Institute in May 2008 to draw attention to the need for partial-body biodosimetry, to discuss current knowledge, and to identify the gaps to be filled. A panel of international experts and the workshop attendees discussed the requirements and concepts for a path forward. This report addresses eight key areas identified by the Workshop Program Committee for future focus: (1) improved cytogenetics, (2) clinical signs and symptoms, (3) cutaneous bioindicators, (4) organ-specific biomarkers, (5) biophysical markers of dose, (6) integrated diagnostic approaches, (7) confounding factors, and (8) requirements for post-event medical follow-up. For each area, the status, advantages and limitations of existing approaches and suggestions for new directions are presented.

Combined approach of hematological biomarkers and plasma protein SAA for improvement of radiation dose assessment triage in biodosimetry applications

Early treatment of populations exposed to ionizing radiation requires accurate and rapid biodosimetry with a precision as high as possible to determine an individual's exposure level and risk for morbidity and mortality. The purpose of this study was to evaluate the utility of multiple blood biomarkers for early-response assessment of radiation exposure using a murine (BALB/c, males) in vivo radiation model. Present results for mice exposed to whole-body Co gamma-rays (0.1 Gy min) over a broad dose range (0-7 Gy) demonstrate at 24 h after exposure: 1) dose-dependent increase in the acute phase protein serum amyloid A or SAA; 2) dose-dependent changes in blood cell counts (lymphocytes, neutrophils, and ratio of neutrophils to lymphocytes); 3) SAA results coupled with peripheral blood cell counts analyzed with use of multivariate discriminant analysis established very successful separation of irradiated animals; 4) an enhanced separation as the number of biomarkers increased. These results also demonstrate proof-in-concept that plasma protein SAA shows promise as a complimentary approach to conventional biodosimetry for early assessment of radiation exposures and, coupled with peripheral blood cell counts, provides early diagnostic information to effectively manage radiation casualty incidents.

Overview of hazard assessment and emergency planning software of use to RN first responders

There are numerous software tools available for field deployment, reach-back, training and planning use in the event of a radiological or nuclear terrorist event. Specialized software tools used by CBRNe responders can increase information available and the speed and accuracy of the response, thereby ensuring that radiation doses to responders, receivers, and the general public are kept as low as reasonably achievable. Software designed to provide health care providers with assistance in selecting appropriate countermeasures or therapeutic interventions in a timely fashion can improve the potential for positive patient outcome. This paper reviews various software applications of relevance to radiological and nuclear events that are currently in use by first responders, emergency planners, medical receivers, and criminal investigators.

Multiple blood-proteins approach for early-response exposure assessment using an in vivo murine radiation model

PURPOSE

The aim was to evaluate the utility of multiple blood-protein biomarkers for early-response assessment of radiation exposure using a murine radiation model system.

MATERIAL AND METHODS

BALB/c male mice (8-10 weeks old) were exposed to whole-body 60Co gamma-rays (10 cGy min(-1)) over a broad dose range (0-7 Gy). Blood protein biomarkers (i.e., Growth Arrest and DNA Damage Inducible Gene 45 or GADD45alpha, interleukin 6 or IL-6, and serum amyloid A or SAA) were measured by enzyme linked immunosorbent assay (ELISA) at 4, 24, 48, and 72 h after total-body irradiation (TBI).

RESULTS

Time- and dose-dependent increases in the protein targets were observed. The use of multiple protein targets was evaluated using multiple linear regression analysis to provide dose-response calibration curves for dose assessment. Multivariate discriminant analysis demonstrated enhanced dose-dependent separation of irradiated animals from control as the number of biomarkers increased.

CONCLUSIONS

Results from this study represent a proof-of-concept for multiple blood-proteins biodosimetry approach. It was demonstrated for the first time that protein expression profile could be developed not only to assess radiation exposure in male BALB/c mice but also to distinguish the level of radiation exposure, ranging from 1-7 Gy.

NASA Radiation Biomarker Workshop, September 27-28, 2007

A summary is provided of presentations and discussions at the NASA Radiation Biomarker Workshop held September 27-28, 2007 at NASA Ames Research Center in Mountain View, CA. Invited speakers were distinguished scientists representing key sectors of the radiation research community. Speakers addressed recent developments in the biomarker and biotechnology fields that may provide new opportunities for health-related assessment of radiation-exposed individuals, including those exposed during long-duration space travel. Topics discussed included the space radiation environment, biomarkers of radiation sensitivity and individual susceptibility, molecular signatures of low-dose responses, multivariate analysis of gene expression, biomarkers in biodefense, biomarkers in radiation oncology, biomarkers and triage after large-scale radiological incidents, integrated and multiple biomarker approaches, advances in whole-genome tiling arrays, advances in mass spectrometry proteomics, radiation biodosimetry for estimation of cancer risk in a rat skin model, and confounding factors. A summary of conclusions is provided at the end of the report.

Sample Tracking in an Automated Cytogenetic Biodosimetry Laboratory for Radiation Mass Casualties

Chromosome aberration-based dicentric assay is expected to be used after mass casualty life-threatening radiation exposures to assess radiation dose to individuals. This will require processing of a large number of samples for individual dose assessment and clinical triage to aid treatment decisions. We have established an automated, high-throughput, cytogenetic biodosimetry laboratory to process a large number of samples for conducting the dicentric assay using peripheral blood from exposed individuals according to internationally accepted laboratory protocols (i.e., within days following radiation exposures). The components of an automated cytogenetic biodosimetry laboratory include blood collection kits for sample shipment, a cell viability analyzer, a robotic liquid handler, an automated metaphase harvester, a metaphase spreader, high-throughput slide stainer and coverslipper, a high-throughput metaphase finder, multiple satellite chromosome-aberration analysis systems, and a computerized sample tracking system. Laboratory automation using commercially available, off-the-shelf technologies, customized technology integration, and implementation of a laboratory information management system (LIMS) for cytogenetic analysis will significantly increase throughput.This paper focuses on our efforts to eliminate data transcription errors, increase efficiency, and maintain samples' positive chain-of-custody by sample tracking during sample processing and data analysis. This sample tracking system represents a "beta" version, which can be modeled elsewhere in a cytogenetic biodosimetry laboratory, and includes a customized LIMS with a central server, personal computer workstations, barcode printers, fixed station and wireless hand-held devices to scan barcodes at various critical steps, and data transmission over a private intra-laboratory computer network. Our studies will improve diagnostic biodosimetry response, aid confirmation of clinical triage, and medical management of radiation exposed individuals.

Use of a centrifuge-based automated blood cell counter for radiation dose assessment

Hematological changes create early-response biomarkers for assessing radiation doses. Existing dose-prediction models are based on serial blood lymphocyte counts after acute whole-body exposure to gamma-radiation. Measurements of lymphocyte-depletion kinetics after possible exposures are useful for triaging patients and managing medical resources. The small-footprint QBC Autoread Plus System provides cost-effective hematological analyses with reproducibility, accuracy, and a broad dynamic range. QBC analysis measures centrifugally packed, whole blood cells in microhematocrit tubes and reports pooled lymphocyte and monocyte counts. Our objective was to modify this procedure to report pure lymphocyte counts for radiation biodosimetry applications. The CD14 antigen is strongly expressed on most human monocytes. Using anti-CD14-coated Dynabeads, we have devised a rapid method for depleting monocytes from whole blood without altering the lymphocyte viability or count. This simple dry procedure provides reliable lymphocyte counts for results that fall within the normal lymphocyte count range (1-4 x 10(9) cells per L) for radiation exposure assessment using lymphocyte-depletion kinetics.

Early-response biological dosimetry--recommended countermeasure enhancements for mass-casualty radiological incidents and terrorism

The effective medical management of a suspected acute radiation overexposure incident necessitates recording dynamic medical data, measuring appropriate radiation bioassays, and estimating dose from dosimeters and radioactivity assessments in order to provide diagnostic information to the treating physician and a dose assessment for personnel radiation protection records. The accepted generic multiparameter and early-response approach includes measuring radioactivity and monitoring the exposed individual; observing and recording prodromal signs/symptoms and erythema; obtaining complete blood counts with white blood cell differential; sampling blood for the chromosome-aberration cytogenetic bioassay using the "gold standard" dicentric assay (translocation assay for long times after exposure) for dose assessment; bioassay sampling, if appropriate, to determine radioactivity contamination; and using other available dosimetry approaches. In the event of a radiological mass-casualty incident, current national resources need to be enhanced to provide suitable dose assessment and medical triage and diagnoses. This capability should be broadly based and include stockpiling reagents and devices; establishing deployable (i.e., hematology and biodosimetry) laboratories and reference (i.e., cytogenetic biodosimetry, radiation bioassay) laboratories; networking qualified reference radioactivity-counting bioassay laboratories, cytogenetic biodosimetry, and deployable hematology laboratories with the medical responder community and national radiation protection program; and researching efforts to identify novel radiation biomarkers and develop applied biological dosimetry assays monitored with clinical, deployable, and hand-held analytical systems. These research and applied science efforts should ultimately contribute towards approved, regulated biodosimetry devices or diagnostic tests integrated into a national radioprotection program.

Quantification of total mitochondrial DNA and the 4977-bp common deletion in Pearson's syndrome lymphoblasts using a fluorogenic 5'-nuclease (TaqMan) real-time polymerase chain reaction assay and plasmid external calibration standards

This study describes a multiplex real-time polymerase chain reaction (PCR) assay that quantifies total mitochondrial DNA (mtDNA(total)) and mtDNA bearing the 4977-base pair 'common deletion' (deltamtDNA4977) in lymphoblasts derived from an individual diagnosed with Pearson's syndrome. The method is unique in its use of plasmids as external quantification standards and its use of multiplex conditions. Standards are validated by comparison with purified mtDNA amplification curves and by the fact that curves are largely unaffected by nuclear DNA (nucDNA). Finally, slopes of standard curves and unknowns are shown to be similar to each other and to theoretical predictions. From these data, mtDNA(total) in these cells is calculated to be 3258 (+723/-592) copies per cell while deltamtDNA4977 averages 232 (+136/-86) copies per cell or 7% (+4.65/-2.81).

Premature chromosome condensation in human resting peripheral blood lymphocytes for chromosome aberration analysis using specific whole-chromosome DNA hybridization probes

This paper describes a unique, simple, and rapid method for inducing premature chromosome condensation (PCC) in "resting" human peripheral blood lymphocytes (HPBLs) and also explains an approach to studying numerical changes and/or structural aberrations involving specific chromosomes. HPBLs are isolated from whole blood on a density gradient and, to induce PCC, are incubated at 37 degrees C in cell culture medium supplemented with a phosphatase inhibitor (okadaic acid or calyculin A), adenosine triphosphate (ATP), and p34cdc2/cyclin B kinase (an essential component of mitosis-promoting factor [MPF]). PCC spreads are prepared on glass slides after a brief hypotonic treatment of cells and fixing in acetic acid/methanol fixative. Aberrations involving specific chromosomes are analyzed after in situ hybridization and chromosome painting by fluorescence microscopy. Normal (undamaged) cells display two fluorescent spots per chromosome, whereas aneuploid cells, or cells with a structural aberration involving the specific chromosome corresponding to the painting probe, may show more than two spots. This method may be used in many biological and toxicological fields that require analysis of numerical and structural aberrations involving specific chromosomes.

Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group

Physicians, hospitals, and other health care facilities will assume the responsibility for aiding individuals injured by a terrorist act involving radioactive material. Scenarios have been developed for such acts that include a range of exposures resulting in few to many casualties. This consensus document was developed by the Strategic National Stockpile Radiation Working Group to provide a framework for physicians in internal medicine and the medical subspecialties to evaluate and manage large-scale radiation injuries. Individual radiation dose is assessed by determining the time to onset and severity of nausea and vomiting, decline in absolute lymphocyte count over several hours or days after exposure, and appearance of chromosome aberrations (including dicentrics and ring forms) in peripheral blood lymphocytes. Documentation of clinical signs and symptoms (affecting the hematopoietic, gastrointestinal, cerebrovascular, and cutaneous systems) over time is essential for triage of victims, selection of therapy, and assignment of prognosis. Recommendations based on radiation dose and physiologic response are made for treatment of the hematopoietic syndrome. Therapy includes treatment with hematopoietic cytokines; blood transfusion; and, in selected cases, stem-cell transplantation. Additional medical management based on the evolution of clinical signs and symptoms includes the use of antimicrobial agents (quinolones, antiviral therapy, and antifungal agents), antiemetic agents, and analgesic agents. Because of the strong psychological impact of a possible radiation exposure, psychosocial support will be required for those exposed, regardless of the dose, as well as for family and friends. Treatment of pregnant women must account for risk to the fetus. For terrorist or accidental events involving exposure to radioiodines, prophylaxis against malignant disease of the thyroid is also recommended, particularly for children and adolescents.