Variable sensitivity of chromosomes 2, 8 and 14 in human peripheral blood lymphocytes exposed to heavy ions

Purpose: To investigate by FISH the distribution of radiation-induced chromosomal aberrations in chromosomes 2, 8 and 14 of 6 donors. Methods: Irradiation of blood from 6 healthy donors (4 male and 2 female) was performed at the accelerators at the Joint Institute for Nuclear Research in Dubna (Russia). Whole blood samples were irradiation with 3 Gy of protons (Phasotron), 3 Gy of 12C-ions (Nuclotron), 4 Gy of 7Li-ions and 3Gy of 11B-ions (Cyclotron U400M). At the position of the samples the beams energy and LET values were following: protons 170 MeV/n and LET ≈ 0.5 keV/µm; 12C 480 MeV/n and LET = 10.6 keV/µm; 7Li 30 MeV/n and LET ≈ 20 keV/µm; 11B 32 MeV/n and LET ≈ 55 keV/µm. Chromosome aberrations were analyzed in prematurely condensed G2-cells harvested after 48 in culture using calyculin A. Chromosomes 2, 8 and 14 were painted in different colors and aberrations scored with the help of an image-analysis system. Results: Chromosome 2 was generally less sensitive than expected on the basis of its DNA content. A higher than expected frequency of exchanges was found in chromosome 8, however, variable results were obtained for stable and unstable aberrations. The translocation frequency was higher and dicentric frequency was lower then expected. Chromosome 14 revealed the opposite tendency: for stable exchanges we found a lower sensitivity whereas the frequency of unstable exchanges was higher then expected. Generally, chromosome 14 was found to be less radiosensitive than expected. Conclusion: Chromosome 2 appears to be less sensitive to protons as well as to heavy ions than chromosomes 8 and 14. This result is in line with recent results of a study on the sensitivity of chromosomes 2, 8 and 14 to gamma rays

CABAS: A freely available PC program for fitting calibration curves in chromosome aberration dosimetry

The aim of biological dosimetry is to estimate the dose and the associated uncertainty to which an accident victim was exposed. This process requires the use of the maximum-likelihood method for fitting a calibration curve, a procedure that is not implemented in most statistical computer programs. Several laboratories have produced their own programs, but these are frequently not user-friendly and not available to outside users. We developed a software for fitting a linear-quadratic dose-response relationship by the method of maximum-likelihood and for estimating a dose from the number of aberrations observed. The program called as CABAS consists of the main curve-fitting and dose estimating module and modules for calculating the dose in cases of partial body exposure, for estimating the minimum number of cells necessary to detect a given dose of radiation and for calculating the dose in the case of a protracted exposure. © The Author 2007. Published by Oxford University Press. All rights reserved

Radiation-induced changes in levels of selected proteins in peripheral blood serum of breast cancer patients as a potential triage biodosimeter for large-scale radiological emergencies

The threat of a large scale radiological emergency, where thousands of people may require fast biological dosimetry for the purpose of triage, makes it necessary to search for new, high throughput biological dosimeters. The authors tested an assay based on the quantitative analysis of selected proteins in peripheral blood serum. They were particularly interested in testing proteins that are specific to irradiation of skin, as these can be used in cases of partial body exposure. Candidate proteins were identified in an earlier study with mice, where skin of the animals was exposed to different doses of radiation and global expression of serum proteins was analyzed. Eight proteins were found, the expression of which showed a consistent dose-response relationship. Human analogues of these proteins were identified, and their expression was measured in peripheral blood serum of 16 breast cancer patients undergoing external beam radiotherapy. The proteins were Apolipoprotein E; Apolipoprotein H; Complement protein 7; Prothrombinase; Pantothenate Kinase 4; Alpha-2-macroglobulin; Fetuin B and Alpha-1-Anti-Chymotrypsin. Measurements were carried out in blood samples collected prior to exposure (control), on the day after one fraction (2 Gy), on the day after five fractions (10 Gy), on the day after 10 fractions (20 Gy), and 1 mo after 23-25 fractions (total dose of 46-50 Gy). Multivariate analysis was carried out, and a multinomial logistic regression model was built. The results. © 2014 Health Physics Society

Web-based scoring of the dicentric assay, a collaborative biodosimetric scoring strategy for population triage in large scale radiation accidents

In the case of a large scale radiation accident high throughput methods of biological dosimetry for population triage are needed to identify individuals requiring clinical treatment. The dicentric assay performed in web-based scoring mode may be a very suitable technique. Within the MULTIBIODOSE EU FP7 project a network is being established of 8 laboratories with expertise in dose estimations based on the dicentric assay. Here, the manual dicentric assay was tested in a web-based scoring mode. More than 23,000 high resolution images of metaphase spreads (only first mitosis) were captured by four laboratories and established as image galleries on the internet (cloud). The galleries included images of a complete dose effect curve (0-5.0 Gy) and three types of irradiation scenarios simulating acute whole body, partial body and protracted exposure. The blood samples had been irradiated in vitro with gamma rays at the University of Ghent, Belgium. Two laboratories provided image galleries from Fluorescence plus Giemsa stained slides (3 h colcemid) and the image galleries from the other two laboratories contained images from Giemsa stained preparations (24 h colcemid). Each of the 8 participating laboratories analysed 3 dose points of the dose effect curve (scoring 100 cells for each point) and 3 unknown dose points (50 cells) for each of the 3 simulated irradiation scenarios. At first all analyses were performed in a QuickScan Mode without scoring individual chromosomes, followed by conventional scoring (only complete cells, 46 centromeres). The calibration curves obtained using these two scoring methods were very similar, with no significant difference in the linear-quadratic curve coefficients. Analysis of variance showed a significant effect of dose on the yield of dicentrics, but no significant effect of the laboratories, different methods of slide preparation or different incubation times used for colcemid. The results obtained to date within the MULTIBIODOSE project by a network of 8 collaborating laboratories throughout Europe are very promising. The dicentric assay in the web based scoring mode as a high throughput scoring strategy is a useful application for biodosimetry in the case of a large scale radiation accident

An automated fitting procedure and software for dose-response curves with multiphasic features

This is the final version of the article. It first appeared from NPG via http://dx.doi.org/10.1038/srep14701In cancer pharmacology (and many other areas), most dose-response curves are satisfactorily described by a classical Hill equation (i.e. 4 parameters logistical). Nevertheless, there are instances where the marked presence of more than one point of inflection, or the presence of combined agonist and antagonist effects, prevents straight-forward modelling of the data via a standard Hill equation. Here we propose a modified model and automated fitting procedure to describe dose-response curves with multiphasic features. The resulting general model enables interpreting each phase of the dose-response as an independent dose-dependent process. We developed an algorithm which automatically generates and ranks dose-response models with varying degrees of multiphasic features. The algorithm was implemented in new freely available Dr Fit software (sourceforge.net/projects/drfit/). We show how our approach is successful in describing dose-response curves with multiphasic features. Additionally, we analysed a large cancer cell viability screen involving 11650 dose-response curves. Based on our algorithm, we found that 28% of cases were better described by a multiphasic model than by the Hill model. We thus provide a robust approach to fit dose-response curves with various degrees of complexity, which, together with the provided software implementation, should enable a wide audience to easily process their own data.This work was funded by Cancer Research UK grant C14303/A17197