Prediction of split dose experiments with GLOBLE parameters derived from dose rate experiments.

<p>This figure shows the survival probability of a LL cell line measured in a split dose experiment with 5+5 Gy (dots) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Stephens1" target="_blank">[37]</a>. The data can be accurately reproduced by a fit of the GLOBLE (dashed line). Although the trend is the same, there are systematic deviations if survival probabilities are predicted with the GLOBLE under application of parameters gained from a dose rate experiment with the same cell line (dotted line).</p

Parameter values derived from fits of the GLOBLE to experimental data.

<p>Here, parameters derived with fits of the GLOBLE to dose rate or split dose experiments in 17 cell lines are listed. These parameter values are – according to the concept – predictive for the radiation response of the investigated cell lines.</p

Description of cell survival probabilities after split dose experiments with the GLOBLE.

<p>The lines in this figure represent a fit of the GLOBLE to survival curves of the MT cell line. The experimental data (markers) were taken from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Stephens1" target="_blank">[37]</a>. In this split dose experiment the cells were irradiated with two times 5 Gy (dots) or two times 6 Gy (squares) and the survival probabilities were recorded in dependence of the time of separation in between the fractions. The measured data are well described by a common set of parameters {ε_i, ε_c and <i>HLT_i</i>} which is – according to the concept – predictive for the cellular response.</p

Description of dose rate specific cell survival probabilities with the GLOBLE.

<p>The lines in this figure represent fits of the GLOBLE to survival curves of the RT112 (A) and MT (B) cell lines. The experimental data (markers) were taken from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-RuizdeAlmodvar1" target="_blank">[39]</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Stephens1" target="_blank">[37]</a>.In both experiments the cell lines were treated with different dose rates and the survival probabilities were recorded. In each panel, the measured data are well described by a common set of parameters {ε_i, ε_c and <i>HLT_i</i>} which is – according to the concept – predictive for the cellular response.</p

Comparison of the GLOBLE and the Linear Quadratic model extended by Lea and Catcheside.

<p>A: The Lea-Catcheside factor and its GLOBLE-equivalent are plotted in dependence of the protraction time <i>T</i>. Three hypothetical cell lines with different values of α/β were chosen. The employed parameters are: α/β = 1 Gy with α = 0.025/Gy, β = 0.025/Gy², ε_i = 0.00083, ε_c = 0.17; α/β = 5.26 Gy with α = 0.15/Gy, β = 0.0285/Gy², ε_i = 0.002, ε_c = 0.2; α/β = 14.4 Gy with α = 0.36/Gy, β = 0.025/Gy², ε_i = 0.012, ε_c = 0.19. For all α/β: <i>r</i>  =  <i>(r_i + m_i)</i>  =  ln(2)/(0.5 h) and <i>(r_c + m_c)</i>  =  ln(2)/(5 h). Please note that all the lines lie on top of each other. B: The relative deviation of the Lea-Catcheside factor and its GLOBLE-equivalent are plotted over the protraction time <i>T</i> for different values of α/β.</p

Comparison of half-life times of DSB repair determined with different models.

<p>Different cell line specific half-life times of DSB repair in h are presented in this table. The experimental values were gained with exponential recovery fits to split dose experiments <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Steel1" target="_blank">[21]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Stackhouse1" target="_blank">[33]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Kelland1" target="_blank">[36]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Stephens1" target="_blank">[37]</a>. The listed values resulting from a fit of the Incomplete Repair model (IR model) or the Lethal Potentially Lethal model (LPL model) to cell survival curves are taken from the following publications: <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Kelland1" target="_blank">[36]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Stephens1" target="_blank">[37]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Holmes1" target="_blank">[40]</a>. The values given for the GLOBLE (which correspond to <i>HLT_i</i>) were determined with fits to experimentally measured cell survival data as shown in the results of this paper. The relative deviation of the half-life times derived with the models to the experimental one are written in parentheses.</p

Prediction of the dose rate dependence of deterministic radiation effects.

<p>The solid lines show the empirical dose rate dependence of the dose implying a 50% probability for the incidence of pneumonitis and the bone marrow syndrome after an exposure as presented by Edward and Lloyds <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083923#pone.0083923-Edwards1" target="_blank">[43]</a>. The order of magnitude of the dose rate dependence can be predicted with the GLOBLE if a reasonable range of half-life times of isolated DSBs <i>HLT_i</i> from 0.1 h to 1 h is assumed (dashed and dotted lines). The shape of the empirical curve for pneumonitis is in good agreement with the GLOBLE prediction down to ≈3 Gy/h if <i>HLT_i</i> is set to 0.5 h which corresponds to the median of half-life times derived from in vitro data.</p

Cell survival data from literature chosen for performance tests.

<p>This table presents experimental data which were chosen for the examination of the kinetically extended GLOBLE. The treated cell lines and the dose rates that were applied during the dose rate effect experiments are listed. In case that survival probabilities after split dose experiments were presented in the publication, the applied doses are noted in the last column. The expected bias in measurements due to cell cycle effects is categorized as follows: “None¹”: Synchronization in G1; “None²”: The population doubling time is much larger than the maximum irradiation time and the applied dose rates make cell cycle effects unlikely; “Unlikely”: The applied dose rates make cell cycle effects unlikely; “Not evident”: The authors state that no bias is evident in the data; “Possible”: The authors state that cell cycle effects cannot be ruled out. For the quantitative investigations of the GLOBLE, the HX99 cell line was excluded. For more explanations see text.</p

Knockdown of SMC1 or MRE11 does not influence mobility of IRIF.

<p>A) Mean square displacement (msd) of 53BP1 foci after irradiation with Pb (LET: 13500 keV/μm) is plotted against time for wt (blue line), SMC1 knockdown (red line) and MRE11 knockdown cells (green line). B) Western blots of U2OS cells 48 h after knockdown of SMC1 and MRE11 with tubulin as loading control.</p

Inhibition of ATM constricts mobility of 53BP1 foci induced by heavy ion or photon irradiation.

<p>Irradiation of U2OS cells was performed by Cr (LET: 2630 keV/μm) for plots A and C and by 1 Gy X-rays for plots B and D. The mean square displacement (msd) of IRIF is plotted over time. Errors represent SEM. <b>A, B</b>) Msd plots of control (solid squares) (Cr n = 11, X-ray n = 21) and ATM inhibited cells (KU55933 open squares) (Cr n = 31, X-ray n = 11) fitted for subdiffusion (red line) and confined diffusion (blue line). <b>C,D</b>) Bar graphs of the average msd after 100 min observation time by live cell microscopy for control and ATM inhibited cells (KU55933) after irradiation with Cr <b>C</b>) and after irradiation with 1 Gy X-rays <b>D</b>). <b>E</b>) U2OS-53BP1-GFP cells irradiated with 1 Gy X-rays, fixed after 30 min and stained for pATM (red) and DNA (blue). Wt compared to cells treated with 15 μM KU55933 for 2 hours (ATMi) show efficiency of ATM kinase inhibition.</p