<p>Fetal cells from the maternal circulation (FCMBs) have the potential to replace cells from amniotic fluid or chorionic villi in a diagnosis of common chromosomal aneuploidies. Good markers for enrichment and identification are lacking.Blood samples from 78 normal pregnancies were used for testing the marker-set CD105 and CD141 for fetal cell enrichment. Fetal cell candidates were subsequently stained by a cocktail of cytokeratin antibodies, and the gender of the fetal cells was explored by fluorescence in situ hybridization (FISH) of the X and Y chromosomes.Fetal cell candidates could be detected in 91 % of the samples, and in 85 % of the samples, it was possible to obtain X and Y chromosomal FISH results for gender determination. The concordance between gender determined by FISH on fetal cells in maternal blood and gender found at birth reached 100 % if three or more fetal cells with FISH signals could be found in a sample.The marker set identifies fetal cells with specificity high enough to make cell-based noninvasive prenatal diagnosis realistic.</p>

<p>DNA double-strand breaks (DSBs) and blocked replication forks resulting from bulky adducts and inhibitors of replication activate the DNA damage response (DDR), a signaling pathway marked by phosphorylation of histone 2AX (H2AX). The phosphorylated form, gamma-H2AX, accumulates at the site of the damage and can be visualized as foci by immunocytochemistry. The objective of this study was to assess if gamma-H2AX is a reliable biomarker for genotoxic exposures. To this end, we selected 14 well-known genotoxic compounds and compared them with 10 nongenotoxic chemicals, using CHO-9 cells because they are well characterized as to DNA repair and DDR. We quantified gamma-H2AX foci manually and automatically. In addition, total gamma-H2AX activation was determined by flow cytometry. For all chemicals the cytotoxic dose response was assayed by a metabolic cytotoxicity assay. We show that (1) all genotoxic agents induced γH2AX dose-dependently whereas nongenotoxic agents do not; (2) gamma-H2AX was observed for genotoxicants in the cytotoxic dose range, revealing a correlation between cytotoxicity and gamma-H2AX for genotoxic agents; for nongenotoxic agents cytotoxicity was not related to gamma-H2AX; (3) manual scoring of gamma-H2AX and automated scoring provided comparable results, the automated scoring was faster and investigator independent; (4) data obtained by foci counting and flow cytometry showed a high correlation, suggesting that gamma-H2AX scoring by flow cytometry has the potential for high-throughput analysis. However, the microscopic evaluation can provide additional information as to foci size, distribution, colocalization and background staining; (5) gamma-H2AX foci were colocalized with 53BP1 and Rad51, supporting the notion that they represent true DSBs. Collectively, the automated analysis of gamma-H2AX foci allows for rapid determination of genetic damage in mammalian cells. The data revealed that the induction of gamma-H2AX by genotoxicants is related to loss of viability and support gamma-H2AX as a reliable bio-indicator for pretoxic DNA damage.</p>

<p>Recent restrictions on the testing of cosmetic ingredients in animals have resulted in the need to test the genotoxic potential of chemicals exclusively in vitro prior to licensing. However, as current in vitro tests produce some misleading positive results, sole reliance on such tests could prevent some chemicals with safe or beneficial exposure levels from being marketed. The 3D human reconstructed skin micronucleus (RSMN) assay is a promising new in vitro approach designed to assess genotoxicity of dermally applied compounds. The assay utilises a highly differentiated in vitro model of the human epidermis. For the first time, we have applied automated micronucleus detection to this assay using MetaSystems Metafer Slide Scanning Platform (Metafer), demonstrating concordance with manual scoring. The RSMN assay's fixation protocol was found to be compatible with the Metafer, providing a considerably shorter alternative to the recommended Metafer protocol. Lowest observed genotoxic effect levels (LOGELs) were observed for mitomycin-C at 4.8 µg/ml and methyl methanesulfonate (MMS) at 1750 µg/ml when applied topically to the skin surface. In-medium dosing with MMS produced a LOGEL of 20 µg/ml, which was very similar to the topical LOGEL when considering the total mass of MMS added. Comparisons between 3D medium and 2D LOGELs resulted in a 7-fold difference in total mass of MMS applied to each system, suggesting a protective function of the 3D microarchitecture. Interestingly, hydrogen peroxide (H2O2), a positive clastogen in 2D systems, tested negative in this assay. A non-genotoxic carcinogen, methyl carbamate, produced negative results, as expected. We also demonstrated expression of the DNA repair protein N-methylpurine-DNA glycosylase in EpiDerm™. Our preliminary validation here demonstrates that the RSMN assay may be a valuable follow-up to the current in vitro test battery, and together with its automation, could contribute to minimising unnecessary in vivo tests by reducing in vitro misleading positives.</p>

The combination of automatic image acquisition and automatic image analysis of premature chromosome condensation (PCC) spreads was tested as a rapid biodosimeter protocol. Human peripheral lymphocytes were irradiated with (60)Co gamma rays in a single dose of between 1 and 20 Gy, stimulated with phytohaemaglutinin and incubated for 48 h, division blocked with Colcemid, and PCC-induced by Calyculin A. Images of chromosome spreads were captured and analysed automatically by combining the Metafer 4 and CellProfiler platforms. Automatic measurement of chromosome lengths allows the calculation of the length ratio (LR) of the longest and the shortest piece that can be used for dose estimation since this ratio is correlated with ionizing radiation dose. The LR of the longest and the shortest chromosome pieces showed the best goodness-of-fit to a linear model in the dose interval tested. The application of the automatic analysis increases the potential use of the PCC method for triage in the event of massive radiation causalities.

<p>Low temperature (hypothermia) during irradiation leads to a reduced frequency of micronuclei in TK6 cells and it has been suggested that perturbation of cell cycle progression is responsible for this effect. The aim of the study was to test this hypothesis.Human lymphoblastoid TK6 cells were treated by a combination of hypothermia (0.8°C) and ionizing radiation in varying order (hypothermia before, during or after irradiation) and micronuclei were scored. Growth assay and two-dimensional flow cytometry was used to analyze cell cycle kinetics following irradiated of cells at 0.8°C or 37.0°C.The temperature effect was observed at the level of micronuclei regardless of whether cells were cooled during or immediately before or after the radiation exposure. No indication of cell cycle perturbation by combined exposure to hypothermia and radiation could be detected.The protective effect of hypothermia observed at the level of cytogenetic damage was not due to a modulation of cell cycle progression. A possible alternative mechanism and experiments to test it are discussed.</p>

<p>The in vivo comet assay has increasingly been used for regulatory genotoxicity testing in recent years. While it has been demonstrated that the experimental execution of the assay, for example, electrophoresis or scoring, can have a strong impact on the results; little is known on how initial steps, that is, from tissue sampling during necropsy up to slide preparation, can influence the comet assay results. Therefore, we investigated which of the multitude of steps in processing the liver for the comet assay are most critical. All together eight parameters were assessed by using liver samples of untreated animals. In addition, two of those parameters (temperature and storage time of liver before embedding into agarose) were further investigated in animals given a single oral dose of ethyl methanesulfonate at dose levels of 50, 100, and 200 mg/kg, 3 hr prior to necropsy. The results showed that sample cooling emerged as the predominant influence factor, whereas variations in other elements of the procedure (e.g., size of the liver piece sampled, time needed to process the liver tissue post-mortem, agarose temperature, or time of lysis) seem to be of little relevance. Storing of liver samples of up to 6 hr under cooled conditions did not cause an increase in tail intensity. In contrast, storing the tissue at room temperature, resulted in a considerable time-dependent increase in comet parameters. Environ. Mol. Mutagen. 55:114-121, 2014. © 2013 Wiley Periodicals, Inc.</p>

<p>The European Union's Seventh Framework Programme-funded project 'Multi-disciplinary biodosimetric tools to manage high scale radiological casualties' (MULTIBIODOSE) has developed a multiparametric approach to radiation biodosimetry, with a particular emphasis on triage of large numbers of potentially exposed individuals following accidental exposures. In November 2012, an emergency exercise took place which tested the capabilities of the MULTIBIODOSE project partners. The exercise described here had a dual purpose: Intercomparison of (i) three biodosimetric assays, and (ii) the capabilities of the seven laboratories, with regards to provision of triage status for suspected radiation exposed individuals.Three biological dosimetry tools - the dicentric, micronucleus and gamma-H2AX (the phosphorylated form of member X of histone H2A, in response to DNA double-strand breaks) foci assays - were tested, in addition to provision of the triage status results (low exposure: 2 Gy) by the MULTIBIODOSE software. The exercise was run in two modes: An initial triage categorisation of samples (based on the first dose estimates for each assay received from each laboratory) followed by collation of the full set of estimated doses (all the results from all modes of each assay carried out by the participating laboratories) calculated using as many modes of operation as possible of the different assays developed during the project. Simulated acute whole body and partial body exposures were included.The results of the initial triage categorisation and the full comparison of assays and methods within and between laboratories are presented here.The data demonstrate that the MULTIBIODOSE approach of applying multiparametric tools to radiation emergencies is valid and effective.</p>

<p>Detection of rare fetal cells (FCs) in the maternal circulation could be used for non-invasive prenatal diagnosis. Considering that FCs in maternal blood are present in extremely low frequency, manual scanning is cumbersome, time-consuming and unsuitable for clinical applications. As an alternative, we optimized a custom-made classifier for automatic detection of FCs.Using MetaSystems' automated platform, we developed a robust detection algorithm and validated its efficiency on retrieval of rare XY cells in a pure population of XX cells. Slides were scanned for presence of predefined XY cells after fluorescence in situ hybridization (FISH) and primed in situ labeling (PRINS). Retrieval of FCs was also performed on samples from maternal blood.The efficiency of detection of rare XY cells was 88 % using FISH (117/133) in comparison to 78 % (53/68) with PRINS. FC frequencies per 1 ml of maternal blood ranged from 3-6 FCs in normal pregnancies versus 13-21 FCs in Down syndrome pregnancies.Automatic scanning was more efficient and consistent than manual scanning for detection of rare FCs and required considerably less operator time. Automatic scanning using FISH is more sensitive than that using PRINS. The study validates automatic scanning retrieval of FCs from maternal blood. This article is protected by copyright. All rights reserved.</p>

<p>To investigate both the formation of micronuclei (MN) and the induction and subsequent loss of phosphorylated histone H2AX foci (gammaH2AX foci) after in vitro exposure of human lymphocytes to either (60)Co gamma-rays or p(66)+ Be(40) neutrons.MN dose response (DR) curves were obtained by exposing isolated lymphocytes of 10 different donors to doses ranging from 0-4 Gy gamma-rays or 0-2 Gy neutrons. Also, gammaH2AX foci DR curves were obtained following exposure to doses ranging from 0-0.5 Gy of either gamma-rays or neutrons. Foci kinetics for lymphocytes for a single donor exposed to 0.5 Gy gamma-rays or neutrons were studied up to 24 hours post-irradiation.Micronuclei yields following neutron exposure were consistently higher compared to that from (60)Co gamma-rays. All MN yields were over-dispersed compared to a Poisson distribution. Over-dispersion was higher after neutron irradiation for all doses &gt; 0.1 Gy. Up to 4 hours post-irradiation lower yields of neutron-induced gammaH2AX foci were observed. Between 4 and 24 hours the numbers of foci from neutrons were consistently higher than that from gamma-rays. The half-live of foci disappearance is only marginally longer for neutrons compared to that from gamma-rays. Foci formations were more likely to be over-dispersed for neutron irradiations.Although neutrons are more effective to induce MN, the absolute number of induced gammaH2AX foci are less at first compared to gamma-rays. With time neutron-induced foci are more persistent. These findings are helpful for using gammaH2AX foci in biodosimetry and to understand the repair of neutron-induced cellular damage.</p>

Telomere erosion may be counteracted by telomerase. Here we explored telomere length (TL) and telomerase activity (TA) in primary cutaneous T-cell lymphoma (CTCL) by using quantitative polymerase chain reaction and interphase quantitative fluorescence in situ hybridization assays. Samples from patients with S´ezary syndrome (SS), transformed mycosis fungoides (T-MF), and cutaneous anaplastic large cell lymphoma were studied in parallel with corresponding cell lines to evaluate the relevance of TL and TA as target candidates for diagnostic and therapeutic purposes. Compared with controls, short telomeres were observed in aggressive CTCL subtypes such as SS and T-MF and were restricted to neoplastic cells in SS. While no genomic alteration of the hTERT (human telomerase catalytic subunit) locus was observed in patients’ tumor cells, TA was detected. To understand the role of telomerase in CTCL, we manipulated its expression in CTCL cell lines. Telomerase inhibition rapidly impeded in vitro cell proliferation and led to cell death, while telomerase overexpression stimulated in vitro proliferation and clonogenicity properties and favored tumor development in immunodeficient mice. Our data indicate that, besides maintenance of TL, telomerase exerts additional functions in CTCL. Therefore, targeting these functions might represent an attractive therapeutic strategy, especially in aggressive CTCL.

<p>Primary cutaneous large B-cell lymphoma, leg type has been individualized from nodal diffuse large B-cell lymphoma. The objective of this study was to screen primary cutaneous large B-cell lymphoma, leg type for genetic alterations recently described in nodal diffuse large B-cell lymphoma. Skin biopsies from 23 patients were analyzed for IRF4, BCL2, BCL6, and MYC expression. FISH testing was performed for BCL2, BCL6, MYC with separation probes and for CDKN2A and PRDM1/BLIMP1 deletion. Multiple sequential FISH analyses with up to six probes were performed to define samples with multiple cytogenetic alterations. MYD88 mutations were studied by Sanger sequencing. All cases but one displayed at least one genetic alteration (96%). Nine patients exhibited a single genetic mutation and 12 combined several alterations (52%). We observed a split for BCL2, BCL6, or MYC in 1/23, 6/23, and 3/23 of cases, respectively. No double-hit lymphoma was observed. CDKN2A deletion was detected by FISH in only 5/23 cases. BLIMP1 and/or 6q deletion was observed at a higher rate in 10/20 of cases. No correlation between rearrangement and immunohistochemical expression was found for BCL2 or MYC. FISH tracking of sequential hybridizations showed that several alterations were carried by the same nuclei. The p.L265P MYD88 mutation was found in 11/18 (61%) of cases. Contrary to most cutaneous lymphomas that rarely harbor primary genetic alteration of their nodal histological equivalent, primary cutaneous large B-cell lymphoma, leg type seems to be a 'cutaneous counterpart' of activated B-cell-like diffuse large B-cell lymphoma with a similar cytogenetic profile and a high rate of MYD88 oncogenic L265P mutation. This also suggests a common lymphomagenesis with NF-jB activation, strong IRF4 expression and terminal B-cell differentiation blockage. Our data support the use of therapies targeting NF-jB, as most patients displayed disease progression and resistance to conventional therapies.</p>

Vascular endothelial growth factor receptor 2 (VEGFR2) is a crucial mediator of tumour angiogenesis. High expression levels of the receptor have been correlated to poor prognosis in cancer patients. Reliable imaging biomarkers for stratifying patients for anti-angiogenic therapy could therefore be valuable for increasing treatment success rates. The aim of this study was to investigate the pharmacokinetics and angiogenesis imaging abilities of the VEGFR2-targeting positron emission tomography (PET) tracer (R)-[11C]PAQ.(R)-[11C]PAQ was evaluated in the mouse mammary tumour virus-polyoma middle T (MMTV-PyMT) model of metastatic breast cancer. Mice at different stages of disease progression were imaged with (R)-[11C]PAQ PET, and results were compared to those obtained with [18 F]FDG PET and magnetic resonance imaging. (R)-[11C]PAQ uptake levels were also compared to ex vivo immunofluorescence analysis of tumour- and angiogenesis-specific biomarkers. Additional pharmacokinetic studies were performed in rat and mouse.A heterogeneous uptake of (R)-[11C]PAQ was observed in the tumorous mammary glands. Ex vivo analysis confirmed the co-localization of areas with high radioactivity uptake and areas with elevated levels of VEGFR2. In some animals, a high focal uptake was observed in the lungs. The lung uptake correlated to metastatic and angiogenic activity, but not to uptake of [18 F]FDG PET. The pharmacokinetic studies revealed a limited metabolism and excretion during the 1-h scan and a distribution of radioactivity mainly to the liver, kidneys and lungs. In rat, a high uptake was additionally observed in adrenal and parathyroid glands.The results indicate that (R)-[11C]PAQ is a promising imaging biomarker for visualization of angiogenesis, based on VEGFR2 expression, in primary tumours and during metastasis development.

Digital object identifier (DOI): 10.1186/2191-219X-4-17

<p>To analyze the effects of hyaluronic acid of different molecular weights in an experimental model of osteoarthritis in rabbits. forty-four male California rabbits were divided randomly into three groups and underwent resection of the anterior cruciate ligament in his right knee. After three weeks of the surgical procedure began three weekly intra-articular injections of hyaluronic acid native (Polireumin®)-PR, hyaluronic acid branched chain (Synvisc®)-S and 0.9% saline-P. All animals were sacrificed after twelve weeks of surgery and tibial plateau infiltrated the knees were dissected. Histological cartilage of the support areas of the tibial plateaus were stained with Alcian Blue pH 1.0, Alcian Blue pH = 2.5 and toluidine blue for research on the amount of proteoglycans. The intensity of staining was quantified on a Zeiss microscope apparatus Imager Z2 MetaSystems and analyzed by software MetaferMsearch. the effect of chondroprotetor hyaluronic acids used in the study was confirmed when compared to the control group, but the comparison made between them, there was no statistically significant difference regarding chondroprotetion. The hyaluronic acids tested had chondroprotective effect, with no statistical difference with regard to the different molecular weights.</p>

Digital object identifier (DOI): 10.1016/j.rboe.2014.01.007

<p>In the April 2013 issue of Haematologica, Lee <em>et al.</em> have described the <em>TET1</em> genomic breakpoints and clinical features of <em>MLL-TET1</em> rearranged cases of acute leukemia. So far, 13 cases have been reported in the literature, 11 in acute myeloid leukemia (AML) patients and 2 in B-cell precursor acute lymphoblastic leukemia (ALL). It was also recently reported that <em>MLL</em> is fused to <em>TET1</em> in only 5 out of 1,590 <em>MLL</em> rearranged <em>AML</em> cases (0.3%). Although those cases are very uncommon, their study can improve our current understanding of leukemogenesis. We report here the first t(10;11) <em>MLL-TET1</em> positive case of T-cell lymphoblastic lymphoma occurring in a 31-year old male patient, with a subsequent transformation to AML.</p> <p>The patient was referred for a large mediastinal mass and right pleural effusion. Blood cell count showed no abnormalities. Mediastinal and bronchus biopsies led to the diagnosis of a precursor-T-cell lymphoblastic lymphoma (pre-T LBL), expressing CD3, CD5, CD4, CD8 and CD10 antigens, together with a high expression of Ki67 (90%). No expression of CD34 or CD79a was observed. The same cells were observed in pleural fluid that expressed CD3, CD4, CD8, CD2, CD7, CD10 antigens but neither CD34 nor myeloperoxidase. Bone marrow examination and central nervous system imaging did not show any other specific localization. The patient was treated following the Groupe d’Etudes des Lymphomes de l’Adulte (GELA) LL03 protocol, and was considered in complete remission after induction and consolidation phases. A 32×22×48 mm residual mediastinal mass remained after treatment, without hypermetabolic abnormality on the FDG-PET scan and was considered to be fibronecrotic scar tissue. Fourteen months after the diagnosis, during the maintenance therapy, a bone marrow examination was performed for thrombopenia (6 g/L) that revealed a myelomonocytic acute leukemia with trilineage dysplasia. The mediastinal mass remained unchanged on the imaging scan. The patient achieved complete remission after intensive chemotherapy based on cytarabine and daunorubicin, followed by a consolidation course with high-dose cytarabine. A non-familial donor allogeneic bone marrow transplant (10/10 match) was performed four months after the diagnosis of the acute myeloid leukemia that was complicated by a Grade IV acute graft-<em>versus</em>-host disease involving digestive tract, liver and skin. The patient died 54 days after the transplant of bacterial sepsis leading to multi-organ failure.</p>

Environmental factors such as solar ultraviolet (UV) radiation and other external aggressors provide an oxidative challenge that is detrimental to skin health. The levels of endogenous antioxidants decrease with age, thus resulting in less protection and a greater potential for skin damage. The NF-E2-related factor-2 (Nrf2) - antioxidant response element (ARE) pathway is a primary defense mechanism against oxidative stress, and induces the expression of antioxidant, detoxification and repair genes. Activation of ARE-Nrf2 can help restore oxidative homeostasis of the skin and play a role in inflammatory response and DNA repair mechanisms.To evaluate the role of a purified parthenolide-depleted Feverfew (PD-Feverfew) extract on the ARE-Nrf2 pathway and DNA repair in skin cells.These studies were undertaken in primary human keratinocytes or KB cells using Luciferase Promoter assay, siRNA transfection studies, Western blot analyses, Immunofluorescence microscopy, comet assay and quantitative real-time PCR.PD-Feverfew was found to induce Nrf2 nuclear translocation and to increase ARE activity in a dose dependent manner. Furthermore, knockdown of Nrf2 resulted in suppression of PD-Feverfew-induced ARE activity. PD-Feverfew was also found to induce phosphorylation of Akt, a kinase downstream of PI3K. Inhibition of PI3K via pre-treatment with the selective pharmacological inhibitor, LY294002, abolished PD-Feverfew-induced Nrf2/ARE activation. PD-Feverfew also reduced UV-induced DNA damage in a PI3K and Nrf2-dependent manner.Therefore, by increasing endogenous defense mechanisms and aid in DNA repair of damaged skin cells via activation of a PI3K-dependent Nrf2/ARE pathway, PD-Feverfew may help protect the skin from numerous environmental aggressors.

Digital object identifier (DOI): 10.1016/j.jdermsci.2013.08.004

Genetic and biochemical sperm integrity is essential to ensure the reproductive competence. However, spermatogenesis involves physiological changes that could endanger sperm integrity. DNA protamination and apoptosis have been studied extensively. Furthermore, elevated rates of aneuploidy and DNA injury correlate with reproductive failures. Consequently, this study applied the conventional spermiogram method in combination with molecular tests to assess genetic integrity in ejaculate from normozoospermic patients with implantation failure by retrospectively analysing aneuploidy (chromosomes 18, X, Y), DNA fragmentation, externalization of phosphatidylserine and mitochondrial membrane potential status before and after magnetic activated cell sorting (MACS). Aneuploid, apoptotic and DNA-injured spermatozoa decreased significantly after MACS. A positive correlation was detected between reduction of aneuploidy and decreased DNA damage, but no correlation was determined with apoptotic markers. The interactions between apoptotic markers, DNA integrity and aneuploidy, and the effect of MACS on these parameters, remain unknown. In conclusion, use of MACS reduced aneuploidy, DNA fragmentation and apoptosis. A postulated mechanism relating aneuploidy and DNA injury is discussed; on the contrary, cell death markers could not be related. An 'apoptotic-like' route could explain this situation. Genetic and biochemical sperm integrity is essential to ensure reproductive success and support the earliest phases of embryo development. Paradoxically, spermatogenesis involves physiological changes that could endanger the DNA and cell integrity. Sperm-specific mechanisms have been studied extensively, and DNA packaging and programmed cell death (apoptosis) are potentially harmful. Also, elevated rates of chromosomal numerical abnormalities and breakage of sperm DNA have been correlated with reproductive failures. In this context, basic sperm examination methods have been combined with molecular tests to assess genetic integrity. On the other hand, magnetic activated cell sorting (MACS) can reduce the number of programmed-to-death spermatozoa. This system retains damaged spermatozoa, thereby improving the sample's quality. The relationships between apoptosis, DNA integrity and chromosomal abnormalities (aneuploidy) as a whole, and the effect of MACS on these parameters remain unknown. We analysed aneuploidy, DNA damage, and biochemical markers of cell death in ejaculate from normozoospermic patients with implantation failures before and after MACS. Aneuploid, apoptotic and DNA-injured spermatozoa decreased significantly after MACS. A positive correlation was detected between the reduction of aneuploidy and DNA damage; on the contrary, no correlation was determined with apoptotic markers. In conclusion, the use of MACS reduced aneuploidy, DNA breakages and apoptosis. A hypothesized mechanism relating aneuploidy and DNA injury is discussed; on the contrary, death cell markers could not be directly related. An 'apoptotic-like' route could explain this situation.

Meiosis generates haploid cells or spores for sexual reproduction. As a prelude to haploidization, homologous chromosomes pair and recombine to undergo segregation during the first meiotic division. During the entire meiotic prophase of the yeast Saccharomyces cerevisiae, chromosomes perform rapid movements that are suspected to contribute to the regulation of recombination. Here, we investigated the impact of ionizing radiation (IR) on movements of GFP-tagged bivalents in live pachytene cells. We find that exposure of sporulating cultures with >40 Gy (4-krad) X-rays stalls pachytene chromosome movements. This identifies a previously undescribed acute radiation response in yeast meiosis, which contrasts with its reported radioresistance of up to 1,000 Gy in survival assays. A modified 3'-end labeling assay disclosed IR-induced dsDNA breaks (DSBs) in pachytene cells at a linear dose relationship of one IR-induced DSB per cell per 5 Gy. Dihydroethidium staining revealed formation of reactive oxygen species (ROS) in irradiated cells. Immobility of fuzzy-appearing irradiated bivalents was rescued by addition of radical scavengers. Hydrogen peroxide-induced ROS did reduce bivalent mobility similar to 40 Gy X IR, while they failed to induce DSBs. IR- and H2O2-induced ROS were found to decompose actin cables that are driving meiotic chromosome mobility, an effect that could be rescued by antioxidant treatment. Hence, it appears that the meiotic actin cytoskeleton is a radical-sensitive system that inhibits bivalent movements in response to IR- and oxidant-induced ROS. This may be important to prevent motility-driven unfavorable chromosome interactions when meiotic recombination has to proceed in genotoxic environments.

The biological dose of nuclear workers engaged in emergency response tasks at Tokyo Electric Power Company (TEPCO) Fukushima Daiichi Nuclear Power Station was estimated in the present study. As the national core center for radiation emergency medical preparedness in Japan, the National Institute of Radiological Sciences (NIRS) received all individuals who were suspected of being overexposed to acute radiation. In the course of health examinations at NIRS, biological dosimetry was performed by the dicentric chromosome assay (DCA). Twelve individuals were examined from 21 March-1 July 2011. The results indicated that the estimated exposure doses for all individuals were lower than 30 mGy, with the mean value of about 101 mGy. These results by DCA were in accordance with those obtained by physical dosimetry based on personal dosimeter recording assessment. The results corroborate the fact that no acute radiation syndrome was observed among the workers examined.

<p>In order to evaluate DNA damage induced by protons at low and radiotherapeutic doses at the therapeutic proton complex at Ružomberok, Slovak Republic, lymphocytes from umbilical cord blood (UCB) of the same four probands were irradiated in the dose range of 1-200 cGy with γ-rays and protons (200 MeV, irradiation in the Bragg peak). DNA repair γH2AX/53BP1 foci were analyzed by fluorescent microscopy and flow cytometry. Statistically significant effects of radiations were detected by fluorescent microscopy at all doses higher 1 cGy. Almost all distributions of foci in irradiated cells fitted to the Poisson distribution. In general, there was no difference in the levels of γH2AX and 53BP1 foci in irradiated cells. Flow cytometry was less sensitive and detected radiation induced effects at doses of 50 cGy and higher. Factorial analysis of variance in the whole studied dose range has shown no significant effect of radiation quality on number of γH2AX and 53BP1 foci. The ratio of proton-induced foci to γ-ray-induced foci was 0.86  ± 0.16 (53BP1) and 0.99  ± 0.34 (γH2AX) as measured by fluorescent microscopy and 0.99 ± 0.16 (γH2AX) as measured by flow cytometry at the radiotherapeutic dose of 2 Gy.Both flow cytometry and fluorescent microscopy indicated that the average value of relative biological efficiency (RBE) at radiation doses ≥ 20 cGy was about 1.0. Our data that RBE increased at low doses ≤ 20 cGy are relevant both to the development of treatment modalities and exposures that take place during space exploration and should be verified by further studies.</p>

Digital object identifier (DOI): 10.3109/09553002.2013.797619

<p>Hydroquinone (HQ) is found in natural and anthropogenic sources including food, cosmetics, cigarette smoke, and industrial products. In addition to ingestion and dermal absorption, human exposure to HQ may also occur by inhaling cigarette smoke or polluted air. The adverse effects of HQ on respiratory systems have been studied, but genotoxicity HQ on human lung cells is unclear. The aim of this study was to investigate the cytotoxicity and genotoxicity of HQ in human lung alveolar epithelial cells (A549). We found that HQ induced a dose response in cell growth inhibition and DNA damage which was associated with an increase in oxidative stress. Cytotoxicity results demonstrated that HQ was most toxic after 24 h (LC₅₀ = 33 μM) and less toxic after 1 h exposure (LC₅₀ = 59 μM). Genotoxicity of HQ was measured using the Comet assay, H2AX phosphorylation, and chromosome aberration formation. Results from the comet assay revealed that DNA damage was highest during the earlier hours of exposure (1 and 6 h) and thereafter was reduced. A similar pattern was observed for H2AX phosphorylation suggesting that damage DNA may be repaired in later exposure hours. An increase in chromosomal aberration corresponded with maximal DNA damage which further confirmed the genotoxic effects of HQ. To investigate whether oxidative stress was involved in the cytotoxic and genotoxic effects of HQ, cellular glutathione and 8-Oxo-deoguanisone (8-Oxo-dG) formation were measured. A decrease in the reduced glutathione (GSH) and an increase oxidized glutathione (GSSG) was observed during the early hours of exposure which corresponded with elevated 8-Oxo-dG adducts. Together these results demonstrate that HQ exerts its cytotoxic and genotoxic effects in A549 lung cells, probably through DNA damage via oxidative stress.</p>

Digital object identifier (DOI): 10.1007/s10565-013-9247-0