In previous RENEB interlaboratory comparisons based on the manual scoring of dicentric chromosomes, a tendency for systematic overestimation for doses > 2.5 Gy was found. However, these exercises included only very few doses in the high dose range, and they were heterogeneous in terms of radiation quality and evaluation mode, and comparable only to a limited extent. Here, this presumed deviation was explored by investigating three doses > 2.5 Gy. Blood samples were irradiated (2.56, 3.41 and 4.54 Gy) using a 60Co source and sent to 14 member laboratories of the RENEB network, which performed the dicentric chromosome assay (manual and/or semi-automatic scoring) and reported dose estimates. Most participants provided estimates that agreed very well with the physical reference doses and all provided dose estimates were in the correct clinical category (> 2 Gy). The previously observed tendency for a systematic bias across all laboratories was not confirmed. However, tendencies for systematic underestimation were detected for dose estimations for reference doses given in terms of absorbed dose to blood and for some participants, a laboratory-specific trend of systematic under- or overestimation was observed. The importance of regularly performed quality checks for a broad dose range became obvious to avoid misinterpretation of results.

• Klíčová slova
• Biological dosimetry, Dicentric chromosome, Interlaboratory comparison, Ionising radiation, Network, Radiation accident,
• MeSH
• chromozomální aberace * účinky záření   MeSH
• dávka záření MeSH
• laboratoře normy   MeSH
• lidé MeSH
• radioizotopy kobaltu * MeSH
• radiometrie * metody   MeSH
• vztah dávky záření a odpovědi MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• Cobalt-60 MeSH Prohlížeč
• radioizotopy kobaltu * MeSH

Unique 3D tomography apparatus was built and successfully tested in Research Centre Rez. The apparatus allows three-dimensional view into the interior of low-dimension radioactive samples with a diameter up to several tens of millimeters with a betterresolution then 1 mm3 and is designed to detect domains with different levels of radioactivity. Structural inhomogeneities such as cavities, cracks or regions with different chemical composition can be detected using this equipment. The SPECT scanner has been successfully tested on several samples composed of a 3-mm radionuclide source located eccentrically within homogeneous steel bushings. To detect fine cracks inside a small sample, an ultrafine scan of the sample was carried out in the course of 24 hours with a 0.5-mm longitudinal and transverse step and 18° angular step. The exact location and orientation of a fine crack artificially formed inside a sample has been detected.

• MeSH
• algoritmy MeSH
• difuze MeSH
• geologie MeSH
• jednofotonová emisní výpočetní tomografie * MeSH
• oxid křemičitý MeSH
• počítačové zpracování obrazu metody   MeSH
• poréznost MeSH
• radioizotopy kobaltu MeSH
• radiometrie přístrojové vybavení   metody   MeSH
• radon MeSH
• scintilace - počítání MeSH
• software MeSH
• teoretické modely MeSH
• wolfram MeSH
• záření gama MeSH
• zobrazování trojrozměrné * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• granite MeSH Prohlížeč
• oxid křemičitý MeSH
• radioizotopy kobaltu MeSH
• radon MeSH
• wolfram MeSH

The aim of the present study was to evaluate the biodosimetric potential of peripheral blood lymphocytes, particularly of T-cell subsets (null and T helper) and natural killer cells (NK), upon exposure to gamma irradiation (60Co) in vivo. For this purpose, the change in relative numbers of NK cells and T-lymphocyte subsets, as well as in the H2AX phosphorylation rate, were evaluated as potential early markers of the lymphocytic response to irradiation in vivo. These experiments were performed on a Large White Pig model. As a result, significant but not dose-dependent changes in the proportion of lymphocyte subpopulations (NK cells, null and T helper cells) were found after exposure to ionising radiation in vivo. On the other hand, circulating NK cells showed relatively higher radioresistance capacity when compared to the T-lymphocyte subsets; however, gamma-H2AX expression showed no significant difference between the evaluated lymphocyte subsets.

• MeSH
• buňky NK účinky záření   MeSH
• fenotyp MeSH
• fosforylace MeSH
• histony metabolismus   MeSH
• imunofenotypizace MeSH
• ionizující záření MeSH
• lymfocyty cytologie   MeSH
• poškození DNA MeSH
• prasata MeSH
• radioizotopy kobaltu farmakologie   MeSH
• radiometrie metody   MeSH
• T-lymfocyty - podskupiny účinky záření   MeSH
• záření gama MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• histony MeSH
• radioizotopy kobaltu MeSH

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
• Názvy látek
• Cobalt-60 MeSH Prohlížeč
• dimethylsulfoxid MeSH
• ethanol MeSH
• hydroxylový radikál * MeSH
• methanol MeSH
• radioizotopy kobaltu MeSH
• radioprotektivní látky MeSH
• scavengery volných radikálů MeSH

In our experiment, we deal with the phenomenon of radiation hormesis and improvements based on this phenomenon to different growing characteristics of the fast-growing, very feed-efficient, and with a high-yielding carcass hybrid of the Peking duck (Cherry Valley SM3 medium). In the first phase of the project, we exposed hatching duck eggs to low and middle doses of gamma radiation 60Co (0.06-2.00 Gy) before placing them into a setter in the hatchery. We then followed the standards of artificial incubation. The treatment of our chosen doses of gamma radiation has no significant influence on the history and results of hatching (from 85.5% to 92.6%); it was influenced only by the basic management and husbandry of the parent stock. From our observations we confirm that the Peking duck, despite genetic progress, retained its vitality and robustness. Its embryos are not damaged even with a dose of 2 Gy, which is over the deterministic effect of ionizing radiation for vertebrates. At the end of the fatting period a significant drop in plasma phosphorus levels was measured in the ducks; however, it was dependent on the radiation dose to which the hatching eggs were exposed (r = -0.965). A positive effect of radiation hormesis may be expected in the case of 1 Gy dose where the highest values of mean corpuscular hemoglobin, mean corpuscular hemoglobin, combined hemoglobin, and drake weight were measured. Lower and higher doses of ionizing radiation used did not display these effects.

• Klíčová slova
• duck, hormesis, low-dose radiation,
• MeSH
• hormeze MeSH
• kachny fyziologie   MeSH
• náhodné rozdělení MeSH
• ovum fyziologie   účinky záření   MeSH
• radioizotopy kobaltu aplikace a dávkování   MeSH
• rozmnožování účinky záření   MeSH
• vztah dávky záření a odpovědi MeSH
• záření gama * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Cobalt-60 MeSH Prohlížeč
• radioizotopy kobaltu MeSH

A new large-volume metal reference standard has been developed. The intended use is for calibration of free-release radioactivity measurement systems and is made up of cast iron tubes placed inside a box of the size of a Euro-pallet (80 × 120 cm). The tubes contain certified activity concentrations of (60)Co (0.290 ± 0.006 Bq g(-1)) and (110m)Ag (3.05 ± 0.09 Bq g(-1)) (reference date: 30 September 2013). They were produced using centrifugal casting from a smelt into which (60)Co was first added and then one piece of neutron irradiated silver wire was progressively diluted. The iron castings were machined to the desirable dimensions. The final material consists of 12 iron tubes of 20 cm outer diameter, 17.6 cm inner diameter, 40 cm length/height and 245.9 kg total mass. This paper describes the reference standard and the process of determining the reference activity values.

• MeSH
• lidé MeSH
• monitorování radiace metody   MeSH
• nakládání s odpady normy   MeSH
• radioaktivní odpad analýza   MeSH
• radioizotopy kobaltu analýza   MeSH
• referenční standardy MeSH
• stříbro analýza   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• radioaktivní odpad MeSH
• radioizotopy kobaltu MeSH
• stříbro MeSH

Radiotherapy in children causes debilitating cognitive decline, partly linked to impaired neurogenesis. Irradiation targets primarily cancer cells but also endogenous neural stem/progenitor cells (NSPCs) leading to cell death or cell cycle arrest. Here we evaluated the effects of lithium on proliferation, cell cycle and DNA damage after irradiation of young NSPCs in vitro.NSPCs were treated with 1 or 3 mM LiCl and we investigated proliferation capacity (neurosphere volume and bromodeoxyuridine (BrdU) incorporation). Using flow cytometry, we analysed apoptosis (annexin V), cell cycle (propidium iodide) and DNA damage (γH2AX) after irradiation (3.5 Gy) of lithium-treated NSPCs.Lithium increased BrdU incorporation and, dose-dependently, the number of cells in replicative phase as well as neurosphere growth. Irradiation induced cell cycle arrest in G1 and G2/M phases. Treatment with 3 mM LiCl was sufficient to increase NSPCs in S phase, boost neurosphere growth and reduce DNA damage. Lithium did not affect the levels of apoptosis, suggesting that it does not rescue NSPCs committed to apoptosis due to accumulated DNA damage.Lithium is a very promising candidate for protection of the juvenile brain from radiotherapy and for its potential to thereby improve the quality of life for those children who survive their cancer.

• Klíčová slova
• apoptosis, hippocampus, lithium, paediatric oncology, radiotherapy,
• MeSH
• apoptóza účinky léků   účinky záření   MeSH
• chlorid lithný aplikace a dávkování   farmakologie   MeSH
• hipokampus cytologie   účinky léků   účinky záření   MeSH
• kontrolní body buněčného cyklu účinky léků   účinky záření   MeSH
• kultivované buňky MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• nervové kmenové buňky cytologie   účinky léků   účinky záření   MeSH
• neurogeneze účinky léků   fyziologie   účinky záření   MeSH
• novorozená zvířata MeSH
• poškození DNA účinky léků   účinky záření   MeSH
• proliferace buněk účinky léků   účinky záření   MeSH
• průtoková cytometrie MeSH
• radioizotopy kobaltu MeSH
• techniky in vitro MeSH
• záření gama MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorid lithný MeSH
• radioizotopy kobaltu MeSH

PURPOSE: To quantitatively investigate the influence of various •OH (hydroxyl radical) scavengers on the radiation sensitivity of yeast and bacteria, particularly to define the relationship between the protective effect of a scavenger and its •OH scavenging efficiency. MATERIALS AND METHODS: In order to study the protective effect of •OH scavengers we used various concentrations of four scavengers (methanol, potassium formate, ethanol and ascorbic acid) in isotonic salt solutions. These solutions containing live yeast (Saccharomyces cerevisiae) or bacteria (Escherichia coli) were irradiated with (60)Co isotope γ -radiation using two different doses and dose rates. The number of surviving cells was determined prior to and after irradiation both in suspension with and without scavengers. The surviving fractions after irradiation with and without the scavenger were evaluated. RESULTS AND CONCLUSIONS: The main results of the paper were: The surviving fraction increased approximately linearly within the measured interval with increasing concentration of the scavenger. The same dependences were found for the protecting effect depending on the scavenging efficiency. The slopes of these dependences (k) were found to be characteristic for each scavenger. The k value determined the degree in which the scavenging of •OH radicals participated in the protection of living cells. The protective effects of scavengers at the same scavenging efficiency were different and unique for each scavenger. No simple relation was found between the efficiency of scavenger k and the rate constant kOH of the reactions between scavengers and •OH radicals. Our results suggest that the studied scavengers effectively protected yeast and bacteria against ionizing radiation. Although the scavenging of •OH radicals seems to be important for protection of living cells, it is clearly not the only process on which the protection is based.

• MeSH
• Escherichia coli účinky léků   účinky záření   MeSH
• hydroxylový radikál * MeSH
• ionizující záření MeSH
• radioizotopy kobaltu chemie   MeSH
• Saccharomyces cerevisiae účinky léků   účinky záření   MeSH
• scavengery volných radikálů * MeSH
• tolerance záření účinky léků   MeSH
• záření gama MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hydroxylový radikál * MeSH
• radioizotopy kobaltu MeSH
• scavengery volných radikálů * MeSH

For the first time, DNA double-strand breaks (DSBs) were directly visualized in functionally and structurally different chromatin domains of human cells. The results show that genetically inactive condensed chromatin is much less susceptible to DSB induction by gamma-rays than expressed, decondensed domains. Higher sensitivity of open chromatin for DNA damage was accompanied by more efficient DSB repair. These findings follow from comparing DSB induction and repair in two 11 Mbp-long chromatin regions, one with clusters of highly expressed genes and the other, gene-poor, containing mainly genes having only low transcriptional activity. The same conclusions result from experiments with whole chromosome territories, differing in gene density and consequently in chromatin condensation. It follows from our further results that this lower sensitivity of DNA to the damage by ionizing radiation in heterochromatin is not caused by the simple chromatin condensation but very probably by the presence of a higher amount of proteins compared to genetically active and decondensed chromatin. In addition, our results show that some agents potentially used for cell killing in cancer therapy (TSA, hypotonic and hypertonic) influence cell survival of irradiated cells via changes in chromatin structure and efficiency of DSB repair in different ways.

• MeSH
• apoptóza účinky záření   MeSH
• buněčné jádro metabolismus   MeSH
• chromatin účinky záření   MeSH
• chromatinová imunoprecipitace MeSH
• DNA účinky záření   MeSH
• fibroblasty cytologie   metabolismus   účinky záření   MeSH
• fluorescenční protilátková technika MeSH
• G1 fáze fyziologie   účinky záření   MeSH
• histondeacetylasy metabolismus   MeSH
• hybridizace in situ fluorescenční MeSH
• inhibitory enzymů farmakologie   MeSH
• inhibitory histondeacetylas MeSH
• kůže cytologie   metabolismus   účinky záření   MeSH
• kyseliny hydroxamové farmakologie   MeSH
• lidé MeSH
• oprava DNA účinky záření   MeSH
• poškození DNA účinky záření   MeSH
• radioizotopy kobaltu MeSH
• regulace genové exprese účinky záření   MeSH
• S fáze fyziologie   účinky záření   MeSH
• záření gama * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chromatin MeSH
• DNA MeSH
• histondeacetylasy MeSH
• inhibitory enzymů MeSH
• inhibitory histondeacetylas MeSH
• kyseliny hydroxamové MeSH
• radioizotopy kobaltu MeSH
• trichostatin A MeSH Prohlížeč

A comparison of the effects of ultrasound produced by low- and high-frequency ultrasonic apparatuses upon biological systems is one of the basic problems when studying ultrasound cavitation effects. One possibility for how to compare these effects is the indirect method which uses well-known physical quantities characterizing the interaction of ionizing radiation with matter and which also converts these quantities to one common physical quantity. The comparison was performed with two methods applied to the chemical dosimetry of ionizing radiation. The first method employed a two-component dosimeter which is composed of 50 % chloroform and 50 % re-distilled water (i.e. Taplin dosimeter). The other method used a modified iodide dosimeter prepared from a 0.5 M potassium iodide solution. After irradiation or ultrasound exposure, measurable chemical changes occurred in both dosimeters. The longer the exposure, the greater the chemical changes. These effects are described by the relationship of these changes versus the exposure times in both dosimeters. The UZD 21 ultrasonic disintegrator (with a frequency of 20 kHz, 50 % power output) was used as a low-frequency ultrasound source, and the BTL-07 therapeutic instrument (with a frequency of 1 MHz and intensity of 2 W/cm2) was used as a high-frequency cavitation ultrasound source. For comparison, a 60 Co gamma source was applied (60 Co, gamma energies of 1.17 and 1.33 MeV, activity of 14 PBq). Results of this study have demonstrated that the sonochemical products are generated during exposure in the exposed samples of both dosimeters for all apparatuses used. The amount of these products depends linearly upon the exposure time. The resulting cavitation effects were recalculated to a gray-equivalent dose (the proposed unit is cavitation gray [cavitGy]) based on the sonochemical effects compared to the effects of ionizing radiation from the 60 Co source.

• MeSH
• časové faktory MeSH
• chemické modely MeSH
• chloroform chemie   účinky záření   MeSH
• dávka záření * MeSH
• design vybavení MeSH
• jodid draselný chemie   účinky záření   MeSH
• koncentrace vodíkových iontů MeSH
• radioizotopy kobaltu * MeSH
• radiometrie přístrojové vybavení   MeSH
• ultrazvuk * MeSH
• vztah dávky záření a odpovědi MeSH
• záření gama * MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• chloroform MeSH
• jodid draselný MeSH
• radioizotopy kobaltu * MeSH