Davídková, Marie*
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LET spectra can be measured by track-etched detectors. However, these detectors are not able to identify the type of interacting particles. Monte Carlo simulations can provide this missing information. In this work, Monte Carlo simulations based on the EURADOS Work Group 9 experiment consisting of systematic 3D mapping of out-of-field doses and LET spectra in a prototype water phantom were performed. The simulations aimed to identify the types of particles contributing to the out-of-field LET spectra. The total absorbed dose, LET and energy spectra were calculated. The calculated dose distributions and LET spectra were compared with the ones measured by radiophotoluminiscence and track-etched detectors. The out-of-field particles and their LET values were identified. No statistically significant differences between the measured and simulated spectra were revealed in the LET range of 100-2000 keV μm-1.
A compromised detection of radiation-induced plasmid DNA fragments results in underestimation of calculated damage yields. Electrophoretic methods are easy and cheap, but they can only detect a part of the fragments, neglecting the shortest ones. These can be detected with atomic force microscopy, but at the expense of time and price. Both methods were used to investigate their capabilities to detect the DNA fragments induced by high-energetic heavy ions. The results were taken into account in calculations of radiation-induced yields of single and double strand breaks. It was estimated that the double strand break yield is twice as high when the fragments are at least partially detected with the agarose electrophoresis, compared to when they were completely omitted. Further increase by 13% was observed when the measured fragments were corrected for the fraction of the shortest fragments up to 300 base pairs, as detected with the atomic force microscopy. The effect of fragment detection on the single strand break yield was diminished.
The influence of various hydroxyl radical scavengers such as methanol, ethanol and dimethyl sulfoxide on radiation sensitivity of prokaryotic cells (bacteria Escherichia coli) and eukaryotic cells (yeast Saccharomyces cerevisiae and V79 cells-Chinese hamster pulmonary fibroblasts) irradiated by 60Co gamma radiation was investigated. The dependence of radiation sensitivity on dose rate in range from 1.8 to 100 Gy h-1 was evaluated. Survival of cells irradiated by increasing dose rates was followed using clonogenic assay. Specific protective effect was found to be a nonmonotonous function of dose rate with typical maximum at the dose rate range from 50 to 55 Gy h-1 in all studied cell types.
- MeSH
- CHO buňky MeSH
- Cricetulus MeSH
- dimethylsulfoxid farmakologie MeSH
- Escherichia coli účinky léků účinky záření MeSH
- ethanol farmakologie MeSH
- fibroblasty účinky léků účinky záření MeSH
- hydroxylový radikál * MeSH
- methanol farmakologie MeSH
- poškození DNA MeSH
- radiační ochrana MeSH
- radioizotopy kobaltu farmakologie MeSH
- radioprotektivní látky farmakologie MeSH
- Saccharomyces cerevisiae účinky léků účinky záření MeSH
- scavengery volných radikálů farmakologie MeSH
- tolerance záření MeSH
- viabilita buněk účinky záření MeSH
- vztah dávky záření a odpovědi MeSH
- záření gama MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Compromised detection of short DNA fragments can result in underestimation of radiation-induced clustered DNA damage. The fragments can be detected with atomic force microscopy (AFM), followed by image analysis to compute the length of plasmid molecules. Plasmid molecules imaged with AFM are represented by open or closed curves, possibly with crossings. For the analysis of such objects, a dedicated algorithm was developed, and its usability was demonstrated on the AFM images of plasmid pBR322 irradiated with 60Co gamma rays. The analysis of the set of the acquired AFM images revealed the presence of DNA fragments with lengths shorter than 300 base pairs that would have been neglected by a conventional detection method.
Medulloblastoma, the most prevalent brain tumor among children, requires a comprehensive understanding of its cellular characteristics for effective research and treatment. In this study, we focused on DAOY, a permanent cell line of medulloblastoma, and investigated the unique properties of DAOY cells when cultured as floating multicellular aggregates called spheres, as opposed to adherent monolayers. Through our comprehensive analysis, we identified distinct characteristics associated with DAOY spheres. Our findings demonstrate that DAOY spheres express markers for both neural stem cells, such as CD133 (PROM1), and differentiated neurons, exemplified by MAP2. Additionally, our investigation revealed that spheres-derived cells exhibit heightened resistance to ionizing radiation compared to adherent cells. Consequently, our results indicate that caution is advised when interpreting experimental results obtained from adherent cell cultures and extrapolating them to in vivo situations.
- Publikační typ
- časopisecké články MeSH
Due to high biocompatibility, miniaturization, optical transparency and low production cost together with high radiation hardness the diamond-based sensors are considered promising for radiation medicine and biomedicine in general. Here we present detection of fibroblast cell culture properties by nanocrystalline diamond solution-gated field-effect transistors (SG-FET), including effects of gamma irradiation. We show that blank nanocrystalline diamond field-effect biosensors are stable at least up to 300 Gy of γ irradiation. On the other hand, gate current of the diamond SG-FET biosensors with fibroblastic cells increases exponentially over an order of magnitude with increasing radiation dose. Extracellular matrix (ECM) formation is also detected and analyzed by correlation of electronic sensor data with optical, atomic force, fluorescence, and scanning electron microscopies.
Plasmid DNA is commonly used as a simpler substitute for a cell in studies of early effects of ionizing radiation because it allows to determine yields of primary DNA lesions. Experimental studies often employ plasmids of different lengths, in different concentrations in the aqueous solution. Influence of these parameters on the heavy-ion induced yields of primary DNA damage has been studied, using plasmids pUC19 (2686 bp), pBR322 (4361 bp) and pKLAC2 (9107 bp) in 10 and 50 ng/μl concentration. Results demonstrate the impact of plasmid length, while no significant difference was observed between the two concentrations. The uncertainty of the results is discussed.
- MeSH
- algoritmy MeSH
- antioxidancia farmakologie MeSH
- DNA účinky záření MeSH
- ionizující záření MeSH
- lineární přenos energie MeSH
- metoda Monte Carlo MeSH
- nejistota MeSH
- plazmidy účinky záření MeSH
- polypropyleny chemie MeSH
- poškození DNA účinky záření MeSH
- těžké ionty MeSH
- vztah dávky záření a odpovědi MeSH
- záření gama MeSH
- Publikační typ
- časopisecké články MeSH
Targeted alpha therapy with radionuclides undergoing multiple alpha-particle decays is a promising method of nuclear medicine. To study the effectiveness of alpha versus beta emitters, survival of DU145 prostate cancer cells exposed to 223Ra or 177Lu was assessed. Per decay, the cells were much more sensitive to the alpha than beta emitter. However, per unit dose the sensitivities would be comparable, contrary to the well-known evidence, if the decay energy were deposited within the sample completely and homogeneously. Measurements by Timepix detectors showed about three times higher counts of alpha particles above than below the sample. After the first alpha decay of 223Ra to 219Rn, this gas likely moves upwards and its subsequent three alpha decays occur in the upper part of the sample. Correct estimation of absorbed dose is a critical issue when analysing in vitro data and when translating their results to clinical applications.
- MeSH
- alfa částice terapeutické užití MeSH
- lidé MeSH
- radiometrie metody MeSH
- radionuklidy terapeutické užití MeSH
- radium * MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
In recent years, there is an increased interest in using scanning modes in proton therapy, due to the more conformal dose distributions, thanks to the spot-weighted dose delivery. The dose rate in each spot is however much higher than the dose rate when using passive irradiation modes, which could affect the cell response. The purpose of this work was to investigate how the relative biological effectiveness changes along the spread-out Bragg peak created by protons delivered by the pencil beam scanning mode. Cell survival and micronuclei formation were investigated in four positions along the spread-out Bragg peak for various doses. Monte Carlo simulations were used to estimate the dose-averaged linear energy transfer values in the irradiation positions. The cell survival was found to decrease the deeper the sample was placed in the spread-out Bragg peak, which corresponds to the higher linear energy transfer values found using Monte Carlo simulations. The micronuclei frequencies indicate more complex cell injuries at that distal position compared to the proximal part of the spread-out Bragg peak. The relative biological effectiveness determined in this study varies significantly and systematically from 1.1, which is recommended value by the International Commission on Radiation Units, in all the studied positions. In the distal position of spread-out Bragg peak the relative biological effectiveness values were found to be 2.05 ± 0.44, 1.85 ± 0.42, 1.53 ± 0.38 for survival levels 90, 50 and 10%, respectively.
- MeSH
- lidé MeSH
- lineární přenos energie MeSH
- mikrojaderné testy MeSH
- novorozenec MeSH
- počítačová simulace MeSH
- protony * MeSH
- radiometrie MeSH
- relativní biologická účinnost * MeSH
- viabilita buněk účinky záření MeSH
- vztah dávky záření a odpovědi MeSH
- Check Tag
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- časopisecké články MeSH
