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Sample records for genomic instability bystander

  1. BYSTANDER EFFECTS GENOMIC INSTABILITY, ADAPTIVE RESPONSE AND CANCER RISK ASSESSMENT FOR RADIAION AND CHEMICAL EXPOSURES

    Science.gov (United States)

    BYSTANDER EFFECTS, GENOMIC INSTABILITY, ADAPTIVE RESPONSE AND CANCER RISK ASSESSMENT FOR RADIATION AND CHEMICAL EXPOSURESR. Julian PrestonEnvironmental Carcinogenesis Division, U.S. Environmental Protection Agency, Research Triangle Park, N.C. 27711, USAThere ...

  2. Bystander-mediated genomic instability after high LET radiation in murine primary haemopoietic stem cells

    International Nuclear Information System (INIS)

    Bowler, Deborah A.; Moore, Stephen R.; Macdonald, Denise A.; Smyth, Sharon H.; Clapham, Peter; Kadhim, Munira A.

    2006-01-01

    Communication between irradiated and unirradiated (bystander) cells can result in responses in unirradiated cells that are similar to responses in their irradiated counterparts. The purpose of the current experiment was to test the hypothesis that bystander responses will be similarly induced in primary murine stem cells under different cell culture conditions. The experimental systems used here, co-culture and media transfer, are similar in that they both restrict communication between irradiated and bystander cells to media borne factors, but are distinct in that with the media transfer technique, cells can only communicate after irradiation, and with co-culture, cells can communication before, during and after irradiation. In this set of parallel experiments, cell type, biological endpoint, and radiation quality and dose, were kept constant. In both experimental systems, clonogenic survival was significantly decreased in all groups, whether irradiated or bystander, suggesting a substantial contribution of bystander effects (BE) to cell killing. Genomic instability (GI) was induced under all radiation and bystander conditions in both experiments, including a situation where unirradiated cells were incubated with media that had been conditioned for 24 h with irradiated cells. The appearance of delayed aberrations (genomic instability) 10-13 population doublings after irradiation was similar to the level of initial chromosomal damage, suggesting that the bystander factor is able to induce chromosomal alterations soon after irradiation. Whether these early alterations are related to those observed at later timepoints remains unknown. These results suggest that genomic instability may be significantly induced in a bystander cell population whether or not cells communicate during irradiation

  3. Perspectives on the role of bystander effect and genomic instability on therapy-induced secondary malignancy

    International Nuclear Information System (INIS)

    Perumal, Venkatachalam; Raavi, Venkateswarlu; Kanagaraj, Karthik; Shangamithra, V.; Paul, Solomon F.D.; Chinnadurai, M.

    2017-01-01

    Deviation from the orchestra of regulated cell division into unregulated and then result into the formation of tumor, is known as carcinogenesis. While causes and hallmarks of many cancer types are well established, newer concepts on tumor cell response to treatment, challenges established therapeutic regime and drives into alternative toward the better management. The phenomena of therapeutics induced bystander response, and genomic instability on late effects of cancer therapy is emerging as a newer challenge. Bystander response is defined as the manifestation of radiation/chemotherapy drug signatures on the unexposed cells which are in the closer vicinity of the directly exposed; on the other hand, genomic instability is defined as the expression of radiation/chemotherapy drug signatures in the progeny of exposed cells. Unequivocally, existence of those phenomena has been demonstrated with many cell types (both in vitro and in vivo) followed by radiation and widely used chemotherapeutic drugs. Nevertheless, it is also revealed that the effects are variable and depend on dose, type of radiation/chemicals agents, experimental model, type of donor and recipient cells, and biomarkers adopted; moreover, to observe those effects, reactive oxygen species has been reported as leading mediators of those responses when compared to other molecules such as interleukins, cytokines, and inflammatory markers. Available data on those phenomena and our findings suggest that a role of therapeutic drugs induced bystander effects, and genomic instability on the development of secondary malignancy cannot be ruled out completely. (author)

  4. Radiation and chemotherapy bystander effects induce early genomic instability events: telomere shortening and bridge formation coupled with mitochondrial dysfunction.

    LENUS (Irish Health Repository)

    Gorman, Sheeona

    2012-02-01

    The bridge breakage fusion cycle is a chromosomal instability mechanism responsible for genomic changes. Radiation bystander effects induce genomic instability; however, the mechanism driving this instability is unknown. We examined if radiation and chemotherapy bystander effects induce early genomic instability events such as telomere shortening and bridge formation using a human colon cancer explant model. We assessed telomere lengths, bridge formations, mitochondrial membrane potential and levels of reactive oxygen species in bystander cells exposed to medium from irradiated and chemotherapy-treated explant tissues. Bystander cells exposed to media from 2Gy, 5Gy, FOLFOX treated tumor and matching normal tissue showed a significant reduction in telomere lengths (all p values <0.018) and an increase in bridge formations (all p values <0.017) compared to bystander cells treated with media from unirradiated tissue (0Gy) at 24h. There was no significant difference between 2Gy and 5Gy treatments, or between effects elicited by tumor versus matched normal tissue. Bystander cells exposed to media from 2Gy irradiated tumor tissue showed significant depolarisation of the mitochondrial membrane potential (p=0.012) and an increase in reactive oxygen species levels. We also used bystander cells overexpressing a mitochondrial antioxidant manganese superoxide dismutase (MnSOD) to examine if this antioxidant could rescue the mitochondrial changes and subsequently influence nuclear instability events. In MnSOD cells, ROS levels were reduced (p=0.02) and mitochondrial membrane potential increased (p=0.04). These events were coupled with a decrease in percentage of cells with anaphase bridges and a decrease in the number of cells undergoing telomere length shortening (p values 0.01 and 0.028 respectively). We demonstrate that radiation and chemotherapy bystander responses induce early genomic instability coupled with defects in mitochondrial function. Restoring mitochondrial

  5. A biological-based model that links genomic instability, bystander effects, and adaptive response

    International Nuclear Information System (INIS)

    Scott, B.R.

    2004-01-01

    This paper links genomic instability, bystander effects, and adaptive response in mammalian cell communities via a novel biological-based, dose-response model called NEOTRANS 3 . The model is an extension of the NEOTRANS 2 model that addressed stochastic effects (genomic instability, mutations, and neoplastic transformation) associated with brief exposure to low radiation doses. With both models, ionizing radiation produces DNA damage in cells that can be associated with varying degrees of genomic instability. Cells with persistent problematic instability (PPI) are mutants that arise via misrepair of DNA damage. Progeny of PPI cells also have PPI and can undergo spontaneous neoplastic transformation. Unlike NEOTRANS 2 , with NEOTRANS 3 newly induced mutant PPI cells and their neoplastically transformed progeny can be suppressed via our previously introduced protective apoptosis-mediated (PAM) process, which can be activated by low linear energy transfer (LET) radiation. However, with NEOTRANS 3 (which like NEOTRANS 2 involves cross-talk between nongenomically compromised [e.g., nontransformed, nonmutants] and genomically compromised [e.g., mutants, transformants, etc.] cells), it is assumed that PAM is only activated over a relatively narrow, dose-rate-dependent interval (D PAM ,D off ); where D PAM is a small stochastic activation threshold, and D off is the stochastic dose above which PAM does not occur. PAM cooperates with activated normal DNA repair and with activated normal apoptosis in guarding against genomic instability. Normal repair involves both error-free repair and misrepair components. Normal apoptosis and the error-free component of normal repair protect mammals by preventing the occurrence of mutant cells. PAM selectively removes mutant cells arising via the misrepair component of normal repair, selectively removes existing neoplastically transformed cells, and probably selectively removes other genomically compromised cells when it is activated

  6. Bystander effects, adaptive response and genomic instability induced by prenatal irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Streffer, Christian [Institute for Science and Ethics, University Duisburg-Essen, Auf dem Sutan 12, D-45239 Essen (Germany)]. E-mail: streffer.essen@t-online.de

    2004-12-02

    The developing human embryo and fetus undergo very radiosensitive stages during the prenatal development. It is likely that the induction of low dose related effects such as bystander effects, the adaptive response, and genomic instability would have profound effects on embryonic and fetal development. In this paper, I review what has been reported on the induction of these three phenomena in exposed embryos and fetuses. All three phenomena have been shown to occur in murine embryonic or fetal cells and structures, although the induction of an adaptive response (and also likely the induction of bystander effects) are limited in terms of when during development they can be induced and the dose or dose-rate used to treat animals in utero. In contrast, genomic instability can be induced throughout development, and the effects of radiation exposure on genome instability can be observed for long times after irradiation including through pre- and postnatal development and into the next generation of mice. There are clearly strain-specific differences in the induction of these phenomena and all three can lead to long-term detrimental effects. This is true for the adaptive response as well. While induction of an adaptive response can make fetuses more resistant to some gross developmental defects induced by a subsequent high dose challenge with ionizing radiation, the long-term effects of this low dose exposure are detrimental. The negative effects of all three phenomena reflect the complexity of fetal development, a process where even small changes in the timing of gene expression or suppression can have dramatic effects on the pattern of biological events and the subsequent development of the mammalian organism.

  7. Genomic instability induced in distant progeny of bystander cells depends on the connexins expressed in the irradiated cells.

    Science.gov (United States)

    de Toledo, Sonia M; Buonanno, Manuela; Harris, Andrew L; Azzam, Edouard I

    2017-10-01

    To examine the time window during which intercellular signaling though gap junctions mediates non-targeted (bystander) effects induced by moderate doses of ionizing radiation; and to investigate the impact of gap junction communication on genomic instability in distant progeny of bystander cells. A layered cell culture system was developed to investigate the propagation of harmful effects from irradiated normal or tumor cells that express specific connexins to contiguous bystander normal human fibroblasts. Irradiated cells were exposed to moderate mean absorbed doses from 3.7 MeV α particle, 1000 MeV/u iron ions, 600 MeV/u silicon ions, or 137 Cs γ rays. Following 5 h of co-culture, pure populations of bystander cells, unexposed to secondary radiation, were isolated and DNA damage and oxidative stress was assessed in them and in their distant progeny (20-25 population doublings). Increased frequency of micronucleus formation and enhanced oxidative changes were observed in bystander cells co-cultured with confluent cells exposed to either sparsely ionizing ( 137 Cs γ rays) or densely ionizing (α particles, energetic iron or silicon ions) radiations. The irradiated cells propagated signals leading to biological changes in bystander cells within 1 h of irradiation, and the effect required cellular coupling by gap junctions. Notably, the distant progeny of isolated bystander cells also exhibited increased levels of spontaneous micronuclei. This effect was dependent on the type of junctional channels that coupled the irradiated donor cells with the bystander cells. Previous work showed that gap junctions composed of connexin26 (Cx26) or connexin43 (Cx43) mediate toxic bystander effects within 5 h of co-culture, whereas gap junctions composed of connexin32 (Cx32) mediate protective effects. In contrast, the long-term progeny of bystander cells expressing Cx26 or Cx43 did not display elevated DNA damage, whereas those coupled by Cx32 had enhanced DNA

  8. The Role of DNA Methylation Changes in Radiation-Induced Transgenerational Genomic Instability and Bystander Effects in cranial irradiated Mice

    Science.gov (United States)

    Zhang, Meng; Sun, Yeqing; Gao, Yinglong; Zhang, Baodong

    Heavy-ion radiation could lead to genome instability in the germline, and therefore to transgenerational genome and epigenome instability in offspring of exposed males. The exact mechanisms of radiation-induced genome instability in directly exposed and in bystander organ remain obscure, yet accumulating evidence points to the role of DNA methylation changes in genome instability development. The potential of localized body-part exposures to affect the germline and thus induce genome and epigenome changes in the progeny has not been studied. To investigate whether or not the paternal cranial irradiation can exert deleterious changes in the protected germline and the offsprings, we studied the alteration of DNA methylation in the shielded testes tissue. Here we report that the localized paternal cranial irradiation results in a significant altered DNA methylation in sperm cells and leads to a profound epigenetic dysregulation in the unexposed progeny conceived 3 months after paternal exposure. The possible molecular mechanisms and biological consequences of the observed changes are discussed. Keywords: Heavy-ion radiation; Transgenerational effect; Genomic Instability Bystander Effects; DNA methylation.

  9. Is there a common mechanism underlying genomic instability, bystander effects and other nontargeted effects of exposure to ionizing radiation?

    Science.gov (United States)

    Morgan, William F.

    2003-01-01

    A number of nontargeted and delayed effects associated with radiation exposure have now been described. These include radiation-induced genomic instability, death-inducing and bystander effects, clastogenic factors and transgenerational effects. It is unlikely that these nontargeted effects are directly induced by cellular irradiation. Instead, it is proposed that some as yet to be identified secreted factor can be produced by irradiated cells that can stimulate effects in nonirradiated cells (death-inducing and bystander effects, clastogenic factors) and perpetuate genomic instability in the clonally expanded progeny of an irradiated cell. The proposed factor must be soluble and capable of being transported between cells by cell-to-cell gap junction communication channels. Furthermore, it must have the potential to stimulate cellular cytokines and/or reactive oxygen species. While it is difficult to imagine a role for such a secreted factor in contributing to transgenerational effects, the other nontargeted effects of radiation may all share a common mechanism.

  10. Genomic instability after targeted irradiation of human lymphocytes: Evidence for inter-individual differences under bystander conditions

    International Nuclear Information System (INIS)

    Kadhim, Munira A.; Lee, Ryonfa; Moore, Stephen R.; Macdonald, Denise A.; Chapman, Kim L.; Patel, Gaurang; Prise, Kevin M.

    2010-01-01

    Environmental 222 radon exposure is a human health concern, and many studies demonstrate that very low doses of high LET α-particle irradiation initiate deleterious genetic consequences in both irradiated and non-irradiated bystander cells. One consequence, radiation-induced genomic instability (RIGI), is a hallmark of tumorigenesis and is often assessed by measuring delayed chromosomal aberrations. We utilised a technique that facilitates transient immobilization of primary lymphocytes for targeted microbeam irradiation and have reported that environmentally relevant doses, e.g. a single 3 He 2+ particle traversal to a single cell, are sufficient to induce RIGI. Herein we sought to determine differences in radiation response in lymphocytes isolated from five healthy male donors. Primary lymphocytes were irradiated with a single particle per cell nucleus. We found evidence for inter-individual variation in radiation response (RIGI, measured as delayed chromosome aberrations). Although this was not highly significant, it was possibly masked by high levels of intra-individual variation. While there are many studies showing a link between genetic predisposition and RIGI, there are few studies linking genetic background with bystander effects in normal human lymphocytes. In an attempt to investigate inter-individual variation in the induction of bystander effects, primary lymphocytes were irradiated with a single particle under conditions where fractions of the population were traversed. We showed a marked genotype-dependent bystander response in one donor after exposure to 15% of the population. The findings may also be regarded as a radiation-induced genotype-dependent bystander effect triggering an instability phenotype.

  11. Genomic instability after targeted irradiation of human lymphocytes: Evidence for inter-individual differences under bystander conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kadhim, Munira A., E-mail: mkadhim@brookes.ac.uk [School of Life Sciences, Oxford Brookes University, Oxford OX3 0BP (United Kingdom); Lee, Ryonfa [Biophysics, GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Planckstrasse 1, D-64291 Darmstadt (Germany); Moore, Stephen R.; Macdonald, Denise A. [Radiation and Genome Stability Unit, Medical Research Council, Harwell, Oxfordshire OX11 0RD (United Kingdom); Chapman, Kim L. [School of Life Sciences, Oxford Brookes University, Oxford OX3 0BP (United Kingdom); Patel, Gaurang; Prise, Kevin M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast BT9 7BL (United Kingdom)

    2010-06-01

    Environmental {sup 222}radon exposure is a human health concern, and many studies demonstrate that very low doses of high LET {alpha}-particle irradiation initiate deleterious genetic consequences in both irradiated and non-irradiated bystander cells. One consequence, radiation-induced genomic instability (RIGI), is a hallmark of tumorigenesis and is often assessed by measuring delayed chromosomal aberrations. We utilised a technique that facilitates transient immobilization of primary lymphocytes for targeted microbeam irradiation and have reported that environmentally relevant doses, e.g. a single {sup 3}He{sup 2+} particle traversal to a single cell, are sufficient to induce RIGI. Herein we sought to determine differences in radiation response in lymphocytes isolated from five healthy male donors. Primary lymphocytes were irradiated with a single particle per cell nucleus. We found evidence for inter-individual variation in radiation response (RIGI, measured as delayed chromosome aberrations). Although this was not highly significant, it was possibly masked by high levels of intra-individual variation. While there are many studies showing a link between genetic predisposition and RIGI, there are few studies linking genetic background with bystander effects in normal human lymphocytes. In an attempt to investigate inter-individual variation in the induction of bystander effects, primary lymphocytes were irradiated with a single particle under conditions where fractions of the population were traversed. We showed a marked genotype-dependent bystander response in one donor after exposure to 15% of the population. The findings may also be regarded as a radiation-induced genotype-dependent bystander effect triggering an instability phenotype.

  12. Transgenerational induction of leukaemia following parental irradiation. Genomic instability and the bystander in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Lord, B.I. [Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester (United Kingdom)

    2003-07-01

    caused by radiation results in changes to haemopoiesis that demand stem cell proliferation, thus leading to elevated genomic instability which may be exploited by secondary leukaemia inducing agents - and evidence will be presented to demonstrate this potential. Additionally, changes in the regulatory haemopoietic microenvironment can be seen as the in vivo form of the potentiating 'bystander'. (author)

  13. Bystander effects in UV-induced genomic instability: Antioxidants inhibit delayed mutagenesis induced by ultraviolet A and B radiation

    Directory of Open Access Journals (Sweden)

    Dahle Jostein

    2005-01-01

    Full Text Available Abstract Background Genomic instability is characteristic of many types of human cancer. Recently, we reported that ultraviolet radiation induced elevated mutation rates and chromosomal instability for many cell generations after ultraviolet irradiation. The increased mutation rates of unstable cells may allow them to accumulate aberrations that subsequently lead to cancer. Ultraviolet A radiation, which primarily acts by oxidative stress, and ultraviolet B radiation, which initially acts by absorption in DNA and direct damage to DNA, both produced genomically unstable cell clones. In this study, we have determined the effect of antioxidants on induction of delayed mutations by ultraviolet radiation. Delayed mutations are indicative of genomic instability. Methods Delayed mutations in the hypoxanthine phosphoribosyl transferase (hprt gene were detected by incubating the cells in medium selectively killing hprt mutants for 8 days after irradiation, followed by a 5 day period in normal medium before determining mutation frequencies. Results The UVB-induced delayed hprt mutations were strongly inhibited by the antioxidants catalase, reduced glutathione and superoxide dismutase, while only reduced glutathione had a significant effect on UVA-induced delayed mutations. Treatment with antioxidants had only minor effects on early mutation frequenies, except that reduced glutathione decreased the UVB-induced early mutation frequency by 24 %. Incubation with reduced glutathione was shown to significantly increase the intracellular amount of reduced glutathione. Conclusion The strong effects of these antioxidants indicate that genomic instability, which is induced by the fundamentally different ultraviolet A and ultraviolet B radiation, is mediated by reactive oxygen species, including hydrogen peroxide and downstream products. However, cells take up neither catalase nor SOD, while incubation with glutathione resulted in increased intracellular levels of

  14. Detection of genomic instability in α-irradiated and bystander human fibroblasts

    International Nuclear Information System (INIS)

    Ponnaiya, B.; Jenkins-Baker, G.; Bigelow, A.; Marino, S.; Geard, C.R.

    2003-01-01

    Full text: We have previously demonstrated a radiation induced bystander effect using novel co-culturing techniques where irradiated and bystander cells were cultured on two surfaces of mylar separated by media. Here we present data from experiments designed to investigate the induction of chromosomal aberrations in irradiated and bystander fibroblasts using these co-culturing techniques. Immortalized fibroblasts ((BJ1-tert) were cultured on both mylar surfaces and cells on one side were irradiated with 0.1 or 1 Gy -particles (an average of 1 and 10 particles per cell nucleus respectively), the two sides were separated 1 hour post irradiation and analyzed for chromosomal aberrations using standard Giemsa staining at either immediate or delayed time points. At 24-30 hours post irradiation, frequencies of chromosomal aberrations in irradiated populations were increased in a dose dependent manner as expected. Populations that received 0.1 and 1 Gy had 0.3 and 1.3 aberrations/cell; these aberrations were almost exclusively chromosome type aberrations. In contrast, at these times bystander populations had elevated yields of chromatid-type aberrations. When assayed at later times (15-20 population doublings post irradiation) both irradiated and bystander cells demonstrated elevated frequencies of chromatid-type aberrations. Frequencies in the irradiated populations ranged from 0.07 to 0.09 aberrations/ cell at 15 doublings, and 0.09-0.14/cell at 20 doublings, with no apparent dose response. Aberration frequencies in the bystander populations were between 0.08-0.14 per cell at the delayed time points assayed. Interestingly, the chromatid-type aberrations observed immediately post irradiation in the bystander cells, and at later times in both the irradiated and bystander populations were qualitatively similar to those previously observed at delayed times in neutron irradiated epithelial cells. Furthermore, there was a similar lack of a dose response in those studies as

  15. Radiation-induced genomic instability and bystander effects: related inflammatory-type responses to radiation-induced stress and injury? A review.

    Science.gov (United States)

    Lorimore, S A; Wright, E G

    2003-01-01

    To review studies of radiation responses in the haemopoietic system in the context of radiation-induced genomic instability, bystander effects and inflammatory-type processes. There is considerable evidence that cells that themselves are not exposed to ionizing radiation but are the progeny of cells irradiated many cell divisions previously may express a high frequency of gene mutations, chromosomal aberrations and cell death. These effects are collectively known as radiation-induced genomic instability. A second untargeted effect results in non-irradiated cells exhibiting responses typically associated with direct radiation exposure but occurs as a consequence of contact with irradiated cells or by receiving soluble signals from irradiated cells. These effects are collectively known as radiation-induced bystander effects. Reported effects include increases or decreases in damage-inducible and stress-related proteins; increases or decreases in reactive oxygen species, cell death or cell proliferation, and induction of mutations and chromosome aberrations. This array of responses is reminiscent of effects mediated by cytokines and other similar regulatory factors that may involve, but do not necessarily require, gap junction-mediated transfer, have multiple inducers and a variety of context-dependent consequences in different cell systems. That chromosomal instability in haemopoietic cells can be induced by an indirect bystander-type mechanism both in vitro and in vivo provides a potential link between these two untargeted effects and there are radiation responses in vivo consistent with the microenvironment contributing secondary cell damage as a consequence of an inflammatory-type response to radiation-induced injury. Intercellular signalling, production of cytokines and free radicals are features of inflammatory responses that have the potential for both bystander-mediated and persisting damage as well as for conferring a predisposition to malignancy. The

  16. Non-targeted and delayed effects of exposure to ionizing radiation: I. Radiation-induced genomic instability and bystander effects in vitro

    Science.gov (United States)

    Morgan, William F.

    2003-01-01

    A long-standing dogma in the radiation sciences is that energy from radiation must be deposited in the cell nucleus to elicit a biological effect. A number of non-targeted, delayed effects of ionizing radiation have been described that challenge this dogma and pose new challenges to evaluating potential hazards associated with radiation exposure. These effects include induced genomic instability and non-targeted bystander effects. The in vitro evidence for non-targeted effects in radiation biology will be reviewed, but the question as to how one extrapolates from these in vitro observations to the risk of radiation-induced adverse health effects such as cancer remains open.

  17. Non-targeted and delayed effects of exposure to ionizing radiation: II. Radiation-induced genomic instability and bystander effects in vivo, clastogenic factors and transgenerational effects

    Science.gov (United States)

    Morgan, William F.

    2003-01-01

    The goal of this review is to summarize the evidence for non-targeted and delayed effects of exposure to ionizing radiation in vivo. Currently, human health risks associated with radiation exposures are based primarily on the assumption that the detrimental effects of radiation occur in irradiated cells. Over the years a number of non-targeted effects of radiation exposure in vivo have been described that challenge this concept. These include radiation-induced genomic instability, bystander effects, clastogenic factors produced in plasma from irradiated individuals that can cause chromosomal damage when cultured with nonirradiated cells, and transgenerational effects of parental irradiation that can manifest in the progeny. These effects pose new challenges to evaluating the risk(s) associated with radiation exposure and understanding radiation-induced carcinogenesis.

  18. Radiation-induced genomic instability and bystander effects: inter-related inflammatory-type non-targeted effects of exposure to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Wright, E.G. (Molecular and Cellular Pathology Laboratories, Division of Pathology and Neuroscience, Ninewells Hospital and Medical School, Dundee, Scotland (United Kingdom))

    2008-12-15

    The dogma that genetic alterations are restricted to directly irradiated cells has been challenged by observations in which effects of ionizing radiation, characteristically associated with the consequences of energy deposition in the cell nucleus, arise in non-irradiated cells. These, so called, untargeted effects are demonstrated in cells that are the descendants of irradiated cells (radiation-induced genomic instability) or in cells that have communicated with neighbouring irradiated cells (radiation-induced bystander effects). There are also reports of long-range signals in vivo, known as clastogenic factors, with the capacity to induce damage in unirradiated cells. Clastogenic factors may be related to the inflammatory responses that have been implicated in some of the pathological consequences of radiation exposures. The phenotypic expression of untargeted effects reflects a balance between the type of signals produced and the responses of cell populations to such signals, both of which may be significantly influenced by cell type and genotype. There is accumulating evidence that untargeted effects in vitro involve inter-cellular signalling, production of cytokines and free radical generation. These are also features of inflammatory responses in vivo that are known to have the potential for both bystander-mediated and persisting damage as well as for conferring a predisposition to malignancy. At present it is far from clear how untargeted effects contribute to overall cellular radiation responses and in vivo consequences but it is possible that the various untargeted effects may reflect inter-related aspects of a non-specific inflammatory-type response to radiation-induced stress and injury and be involved in a variety of the pathological consequences of radiation exposures. (orig.)

  19. Radiation-induced genomic instability and bystander effects: inter-related inflammatory-type non-targeted effects of exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Wright, E.G.

    2008-01-01

    The dogma that genetic alterations are restricted to directly irradiated cells has been challenged by observations in which effects of ionizing radiation, characteristically associated with the consequences of energy deposition in the cell nucleus, arise in non-irradiated cells. These, so called, untargeted effects are demonstrated in cells that are the descendants of irradiated cells (radiation-induced genomic instability) or in cells that have communicated with neighbouring irradiated cells (radiation-induced bystander effects). There are also reports of long-range signals in vivo, known as clastogenic factors, with the capacity to induce damage in unirradiated cells. Clastogenic factors may be related to the inflammatory responses that have been implicated in some of the pathological consequences of radiation exposures. The phenotypic expression of untargeted effects reflects a balance between the type of signals produced and the responses of cell populations to such signals, both of which may be significantly influenced by cell type and genotype. There is accumulating evidence that untargeted effects in vitro involve inter-cellular signalling, production of cytokines and free radical generation. These are also features of inflammatory responses in vivo that are known to have the potential for both bystander-mediated and persisting damage as well as for conferring a predisposition to malignancy. At present it is far from clear how untargeted effects contribute to overall cellular radiation responses and in vivo consequences but it is possible that the various untargeted effects may reflect inter-related aspects of a non-specific inflammatory-type response to radiation-induced stress and injury and be involved in a variety of the pathological consequences of radiation exposures. (orig.)

  20. Detection of chromosomal instability in α-irradiated and bystander human fibroblasts

    International Nuclear Information System (INIS)

    Ponnaiya, Brian; Jenkins-Baker, Gloria; Bigelow, Alan; Marino, Stephen; Geard, Charles R.

    2004-01-01

    There is increasing evidence biological responses to ionizing radiation are not confined to those cells that are directly hit, but may be seen in the progeny at subsequent generations (genomic instability) and in non-irradiated neighbors of irradiated cells (bystander effects). These so called non-targeted phenomena would have significant contributions to radiation-induced carcinogenesis, especially at low doses where only a limited number of cells in a population are directed hit. Here we present data using a co-culturing protocol examining chromosomal instability in α-irradiated and bystander human fibroblasts BJ1-htert. At the first cell division following exposure to 0.1 and 1 Gy α-particles, irradiated populations demonstrated a dose dependent increase in chromosome-type aberrations. At this time bystander BJ1-htert populations demonstrated elevated chromatid-type aberrations when compared to controls. Irradiated and bystander populations were also analyzed for chromosomal aberrations as a function of time post-irradiation. When considered over 25 doublings, all irradiated and bystander populations had significantly higher frequencies of chromatid aberrations when compared to controls (2-3-fold over controls) and were not dependent on dose. The results presented here support the link between the radiation-induced phenomena of genomic instability and the bystander effect

  1. Radiation-induced instability of human genome

    International Nuclear Information System (INIS)

    Ryabchenko, N.N.; Demina, Eh.A.

    2014-01-01

    A brief review is dedicated to the phenomenon of radiation-induced genomic instability where the increased level of genomic changes in the offspring of irradiated cells is characteristic. Particular attention is paid to the problems of genomic instability induced by the low-dose radiation, role of the bystander effect in formation of radiation-induced instability, and its relationship with individual radiosensitivity. We believe that in accordance with the paradigm of modern radiobiology the increased human individual radiosensitivity can be formed due to the genome instability onset and is a significant risk factor for radiation-induced cancer

  2. Genomic instability and radiation effects

    International Nuclear Information System (INIS)

    Christian Streffer

    2007-01-01

    Complete text of publication follows. Cancer, genetic mutations and developmental abnormalities are apparently associated with an increased genomic instability. Such phenomena have been frequently shown in human cancer cells in vitro and in situ. It is also well-known that individuals with a genetic predisposition for cancer proneness, such as ataxia telangiectesia, Fanconi anaemia etc. demonstrate a general high genomic instability e.g. in peripheral lymphocytes before a cancer has developed. Analogous data have been found in mice which develop a specific congenital malformation which has a genetic background. Under these aspects it is of high interest that ionising radiation can increase the genomic instability of mammalian cells after exposures in vitro an in vivo. This phenomenon is expressed 20 to 40 cell cycles after the exposure e.g. by de novo chromosomal aberrations. Such effects have been observed with high and low LET radiation, high LET radiation is more efficient. With low LET radiation a good dose response is observed in the dose range 0.2 to 2.0 Gy, Recently it has been reported that senescence and genomic instability was induced in human fibroblasts after 1 mGy carbon ions (1 in 18 cells are hit), apparently bystander effects also occurred under these conditions. The instability has been shown with DNA damage, chromosomal aberrations, gene mutation and cell death. It is also transferred to the next generation of mice with respect to gene mutations, chromosomal aberrations and congenital malformations. Several mechanisms have been discussed. The involvement of telomeres has gained interest. Genomic instability seems to be induced by a general lesion to the whole genome. The transmission of one chromosome from an irradiated cell to an non-irradiated cell leads to genomic instability in the untreated cells. Genomic instability increases mutation rates in the affected cells in general. As radiation late effects (cancer, gene mutations and congenital

  3. Genomic instability following irradiation

    International Nuclear Information System (INIS)

    Hacker-Klom, U.B.; Goehde, W.

    2001-01-01

    Ionising irradiation may induce genomic instability. The broad spectrum of stress reactions in eukaryontic cells to irradiation complicates the discovery of cellular targets and pathways inducing genomic instability. Irradiation may initiate genomic instability by deletion of genes controlling stability, by induction of genes stimulating instability and/or by activating endogeneous cellular viruses. Alternatively or additionally it is discussed that the initiation of genomic instability may be a consequence of radiation or other agents independently of DNA damage implying non nuclear targets, e.g. signal cascades. As a further mechanism possibly involved our own results may suggest radiation-induced changes in chromatin structure. Once initiated the process of genomic instability probably is perpetuated by endogeneous processes necessary for proliferation. Genomic instability may be a cause or a consequence of the neoplastic phenotype. As a conclusion from the data available up to now a new interpretation of low level radiation effects for radiation protection and in radiotherapy appears useful. The detection of the molecular mechanisms of genomic instability will be important in this context and may contribute to a better understanding of phenomenons occurring at low doses <10 cSv which are not well understood up to now. (orig.)

  4. Causes of genome instability

    DEFF Research Database (Denmark)

    Langie, Sabine A S; Koppen, Gudrun; Desaulniers, Daniel

    2015-01-01

    function, chromosome segregation, telomere length). The purpose of this review is to describe the crucial aspects of genome instability, to outline the ways in which environmental chemicals can affect this cancer hallmark and to identify candidate chemicals for further study. The overall aim is to make......Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome's integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus...

  5. Genomic instability and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Little, John B [Harvard School of Public Health, Boston, MA 02115 (United States)

    2003-06-01

    Genomic instability is a hallmark of cancer cells, and is thought to be involved in the process of carcinogenesis. Indeed, a number of rare genetic disorders associated with a predisposition to cancer are characterised by genomic instability occurring in somatic cells. Of particular interest is the observation that transmissible instability can be induced in somatic cells from normal individuals by exposure to ionising radiation, leading to a persistent enhancement in the rate at which mutations and chromosomal aberrations arise in the progeny of the irradiated cells after many generations of replication. If such induced instability is involved in radiation carcinogenesis, it would imply that the initial carcinogenic event may not be a rare mutation occurring in a specific gene or set of genes. Rather, radiation may induce a process of instability in many cells in a population, enhancing the rate at which the multiple gene mutations necessary for the development of cancer may arise in a given cell lineage. Furthermore, radiation could act at any stage in the development of cancer by facilitating the accumulation of the remaining genetic events required to produce a fully malignant tumour. The experimental evidence for such induced instability is reviewed. (review)

  6. Genomic instability and radiation

    International Nuclear Information System (INIS)

    Little, John B

    2003-01-01

    Genomic instability is a hallmark of cancer cells, and is thought to be involved in the process of carcinogenesis. Indeed, a number of rare genetic disorders associated with a predisposition to cancer are characterised by genomic instability occurring in somatic cells. Of particular interest is the observation that transmissible instability can be induced in somatic cells from normal individuals by exposure to ionising radiation, leading to a persistent enhancement in the rate at which mutations and chromosomal aberrations arise in the progeny of the irradiated cells after many generations of replication. If such induced instability is involved in radiation carcinogenesis, it would imply that the initial carcinogenic event may not be a rare mutation occurring in a specific gene or set of genes. Rather, radiation may induce a process of instability in many cells in a population, enhancing the rate at which the multiple gene mutations necessary for the development of cancer may arise in a given cell lineage. Furthermore, radiation could act at any stage in the development of cancer by facilitating the accumulation of the remaining genetic events required to produce a fully malignant tumour. The experimental evidence for such induced instability is reviewed. (review)

  7. Genomic instability and the role of radiation quality

    International Nuclear Information System (INIS)

    Kadhim, M. A.; Hill, M. A.; Moore, S. R.

    2006-01-01

    Genomic instability (GI) is a hallmark of tumorigenic progression and is observed as delayed genetic damage in the progeny of irradiated and unirradiated bystander cells. The expression of GI can be influenced by genotype, cell type and radiation quality. While several studies have demonstrated the induction of GI by high and low-linear energy transfer (LET) radiation, our work on human and mouse primary cell systems has shown LET-dependent differences in the induction and expression of GI. These differences might be attributed to differences in radiation track structure, dose rate, contribution of bystander cells and radiation dose. This paper reviews the role of radiation quality in the induction of GI and describe the possible mechanisms underlining the observed differences between radiation types on its induction. The experimental results presented suggest that dose might be the most significant factor in determining induction of GI after low-LET radiation. (authors)

  8. Bystander effects and radiotherapy.

    Science.gov (United States)

    Marín, Alicia; Martín, Margarita; Liñán, Olga; Alvarenga, Felipe; López, Mario; Fernández, Laura; Büchser, David; Cerezo, Laura

    2015-01-01

    Radiation-induced bystander effects are defined as biological effects expressed after irradiation by cells whose nuclei have not been directly irradiated. These effects include DNA damage, chromosomal instability, mutation, and apoptosis. There is considerable evidence that ionizing radiation affects cells located near the site of irradiation, which respond individually and collectively as part of a large interconnected web. These bystander signals can alter the dynamic equilibrium between proliferation, apoptosis, quiescence or differentiation. The aim of this review is to examine the most important biological effects of this phenomenon with regard to areas of major interest in radiotherapy. Such aspects include radiation-induced bystander effects during the cell cycle under hypoxic conditions when administering fractionated modalities or combined radio-chemotherapy. Other relevant aspects include individual variation and genetics in toxicity of bystander factors and normal tissue collateral damage. In advanced radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), the high degree of dose conformity to the target volume reduces the dose and, therefore, the risk of complications, to normal tissues. However, significant doses can accumulate out-of-field due to photon scattering and this may impact cellular response in these regions. Protons may offer a solution to reduce out-of-field doses. The bystander effect has numerous associated phenomena, including adaptive response, genomic instability, and abscopal effects. Also, the bystander effect can influence radiation protection and oxidative stress. It is essential that we understand the mechanisms underlying the bystander effect in order to more accurately assess radiation risk and to evaluate protocols for cancer radiotherapy.

  9. Mechanisms of Low Dose Radio-Suppression of Genomic Instability

    Energy Technology Data Exchange (ETDEWEB)

    Engelward, Bevin P. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2009-09-16

    The major goal of this project is to contribute toward the elucidation of the impact of long term low dose radiation on genomic stability. We have created and characterized novel technologies for delivering long term low dose radiation to animals, and we have studied genomic stability by applying cutting edge molecular analysis technologies. Remarkably, we have found that a dose rate that is 300X higher than background radiation does not lead to any detectable genomic damage, nor is there any significant change in gene expression for genes pertinent to the DNA damage response. These results point to the critical importance of dose rate, rather than just total dose, when evaluating public health risks and when creating regulatory guidelines. In addition to these studies, we have also further developed a mouse model for quantifying cells that have undergone a large scale DNA sequence rearrangement via homologous recombination, and we have applied these mice in studies of both low dose radiation and space radiation. In addition to more traditional approaches for assessing genomic stability, we have also explored radiation and possible beneficial effects (adaptive response), long term effects (persistent effects) and effects on communication among cells (bystander effects), both in vitro and in vivo. In terms of the adaptive response, we have not observed any significant induction of an adaptive response following long term low dose radiation in vivo, delivered at 300X background. In terms of persistent and bystander effects, we have revealed evidence of a bystander effect in vivo and with researchers at and demonstrated for the first time the molecular mechanism by which cells “remember” radiation exposure. Understanding the underlying molecular mechanisms by which radiation can induce genomic instability is fundamental to our ability to assess the biological impact of low dose radiation. Finally, in a parallel set of studies we have explored the effects of heavy

  10. Genome instability: Linking ageing and brain degeneration.

    Science.gov (United States)

    Barzilai, Ari; Schumacher, Björn; Shiloh, Yosef

    2017-01-01

    Ageing is a multifactorial process affected by cumulative physiological changes resulting from stochastic processes combined with genetic factors, which together alter metabolic homeostasis. Genetic variation in maintenance of genome stability is emerging as an important determinant of ageing pace. Genome instability is also closely associated with a broad spectrum of conditions involving brain degeneration. Similarities and differences can be found between ageing-associated decline of brain functionality and the detrimental effect of genome instability on brain functionality and development. This review discusses these similarities and differences and highlights cell classes whose role in these processes might have been underestimated-glia and microglia. Copyright © 2016. Published by Elsevier B.V.

  11. Genome organization, instabilities, stem cells, and cancer

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Pazhanisamy

    2009-01-01

    Full Text Available It is now widely recognized that advances in exploring genome organization provide remarkable insights on the induction and progression of chromosome abnormalities. Much of what we know about how mutations evolve and consequently transform into genome instabilities has been characterized in the spatial organization context of chromatin. Nevertheless, many underlying concepts of impact of the chromatin organization on perpetuation of multiple mutations and on propagation of chromosomal aberrations remain to be investigated in detail. Genesis of genome instabilities from accumulation of multiple mutations that drive tumorigenesis is increasingly becoming a focal theme in cancer studies. This review focuses on structural alterations evolve to raise a variety of genome instabilities that are manifested at the nucleotide, gene or sub-chromosomal, and whole chromosome level of genome. Here we explore an underlying connection between genome instability and cancer in the light of genome architecture. This review is limited to studies directed towards spatial organizational aspects of origin and propagation of aberrations into genetically unstable tumors.

  12. Genome instabilities arising from ribonucleotides in DNA.

    Science.gov (United States)

    Klein, Hannah L

    2017-08-01

    Genomic DNA is transiently contaminated with ribonucleotide residues during the process of DNA replication through misincorporation by the replicative DNA polymerases α, δ and ε, and by the normal replication process on the lagging strand, which uses RNA primers. These ribonucleotides are efficiently removed during replication by RNase H enzymes and the lagging strand synthesis machinery. However, when ribonucleotides remain in DNA they can distort the DNA helix, affect machineries for DNA replication, transcription and repair, and can stimulate genomic instabilities which are manifest as increased mutation, recombination and chromosome alterations. The genomic instabilities associated with embedded ribonucleotides are considered here, along with a discussion of the origin of the lesions that stimulate particular classes of instabilities. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Mechanisms of cadmium induced genomic instability

    Energy Technology Data Exchange (ETDEWEB)

    Filipic, Metka, E-mail: metka.filipic@nib.si [National Institute of Biology, Department for Genetic Toxicology and Cancer Biology, Ljubljana (Slovenia)

    2012-05-01

    Cadmium is an ubiquitous environmental contaminant that represents hazard to humans and wildlife. It is found in the air, soil and water and, due to its extremely long half-life, accumulates in plants and animals. The main source of cadmium exposure for non-smoking human population is food. Cadmium is primarily toxic to the kidney, but has been also classified as carcinogenic to humans by several regulatory agencies. Current evidence suggests that exposure to cadmium induces genomic instability through complex and multifactorial mechanisms. Cadmium dose not induce direct DNA damage, however it induces increase in reactive oxygen species (ROS) formation, which in turn induce DNA damage and can also interfere with cell signalling. More important seems to be cadmium interaction with DNA repair mechanisms, cell cycle checkpoints and apoptosis as well as with epigenetic mechanisms of gene expression control. Cadmium mediated inhibition of DNA repair mechanisms and apoptosis leads to accumulation of cells with unrepaired DNA damage, which in turn increases the mutation rate and thus genomic instability. This increases the probability of developing not only cancer but also other diseases associated with genomic instability. In the in vitro experiments cadmium induced effects leading to genomic instability have been observed at low concentrations that were comparable to those observed in target organs and tissues of humans that were non-occupationally exposed to cadmium. Therefore, further studies aiming to clarify the relevance of these observations for human health risks due to cadmium exposure are needed.

  14. Mechanisms of cadmium induced genomic instability

    International Nuclear Information System (INIS)

    Filipič, Metka

    2012-01-01

    Cadmium is an ubiquitous environmental contaminant that represents hazard to humans and wildlife. It is found in the air, soil and water and, due to its extremely long half-life, accumulates in plants and animals. The main source of cadmium exposure for non-smoking human population is food. Cadmium is primarily toxic to the kidney, but has been also classified as carcinogenic to humans by several regulatory agencies. Current evidence suggests that exposure to cadmium induces genomic instability through complex and multifactorial mechanisms. Cadmium dose not induce direct DNA damage, however it induces increase in reactive oxygen species (ROS) formation, which in turn induce DNA damage and can also interfere with cell signalling. More important seems to be cadmium interaction with DNA repair mechanisms, cell cycle checkpoints and apoptosis as well as with epigenetic mechanisms of gene expression control. Cadmium mediated inhibition of DNA repair mechanisms and apoptosis leads to accumulation of cells with unrepaired DNA damage, which in turn increases the mutation rate and thus genomic instability. This increases the probability of developing not only cancer but also other diseases associated with genomic instability. In the in vitro experiments cadmium induced effects leading to genomic instability have been observed at low concentrations that were comparable to those observed in target organs and tissues of humans that were non-occupationally exposed to cadmium. Therefore, further studies aiming to clarify the relevance of these observations for human health risks due to cadmium exposure are needed.

  15. The bystander effect: is reactive oxygen species the driver?

    International Nuclear Information System (INIS)

    Szumiel, I.

    2003-01-01

    The paper reviews selected examples of the bystander effect, such as clonogenic survival decrease, chromosomal aberrations and mutations. The similarities and differences between the biological effects in directly targeted and bystander cells are briefly discussed. Also reviewed are the experimental data which support the role of reactive oxygen species (ROS), especially *O 2 - , as mediators of the bystander effect. Endogenously generated ROS, due to activation of NAD(P)H oxidases, play a kay role in the introduction of DNA damage in bystander cells. All the observed effects in bystander cells, such as alteration in gene expression patterns, chromosomal aberrations, sister chromatid exchanges, mutations, genome instability and neoplastic transformation are the consequence of DNA damage. (author)

  16. Research for genetic instability of human genome

    Energy Technology Data Exchange (ETDEWEB)

    Hori, T.; Takahashi, E.; Tsuji, H.; Yamauchi, M. (National Inst. of Radiological Sciences, Chiba (Japan)); Murata, M.

    1992-01-01

    In the present review paper, the potential relevance of chromosomal fragile sites to carcinogenesis and mutagenesis is discussed based on our own and other's studies. Recent evidence indicate that fragile sites may act as predisposition factors involved in chromosomal instability of the human genome and that the sites may be preferential targets for various DNA damaging agents including ionizing radiation. It is also demonstrated that some critical genomic rearrangements at the fragile sites may contribute towards oncogenesis and that individuals carrying heritable form of fragile site may be at the risk. Although clinical significance of autosomal fragile sites has been a matter of discussion, a fragile site of the X chromosome is known to be associated with an X-linked genetic diseases, called fragile X syndrome. Molecular events leading to the fragile X syndrome have recently been elucidated. The fragile X genotype can be characterized by an increased amount of p(CCG)n repeat DNA sequence in the FMR-1 gene and the repeated sequences are shown to be unstable in both meiosis and mitosis. These repeats might exhibit higher mutation rate than is generally seen in the human genome. Further studies on the fragile sites in molecular biology and radiation biology will yield relevant data to the molecular mechanisms of genetic instability of the human genome as well as to better assessment of genetic effect of ionizing radiation. (author).

  17. Research for genetic instability of human genome

    International Nuclear Information System (INIS)

    Hori, T.; Takahashi, E.; Tsuji, H.; Yamauchi, M.; Murata, M.

    1992-01-01

    In the present review paper, the potential relevance of chromosomal fragile sites to carcinogenesis and mutagenesis is discussed based on our own and other's studies. Recent evidence indicate that fragile sites may act as predisposition factors involved in chromosomal instability of the human genome and that the sites may be preferential targets for various DNA damaging agents including ionizing radiation. It is also demonstrated that some critical genomic rearrangements at the fragile sites may contribute towards oncogenesis and that individuals carrying heritable form of fragile site may be at the risk. Although clinical significance of autosomal fragile sites has been a matter of discussion, a fragile site of the X chromosome is known to be associated with an X-linked genetic diseases, called fragile X syndrome. Molecular events leading to the fragile X syndrome have recently been elucidated. The fragile X genotype can be characterized by an increased amount of p(CCG)n repeat DNA sequence in the FMR-1 gene and the repeated sequences are shown to be unstable in both meiosis and mitosis. These repeats might exhibit higher mutation rate than is generally seen in the human genome. Further studies on the fragile sites in molecular biology and radiation biology will yield relevant data to the molecular mechanisms of genetic instability of the human genome as well as to better assessment of genetic effect of ionizing radiation. (author)

  18. Evaluation of Genomic Instability in the Abnormal Prostate

    National Research Council Canada - National Science Library

    Haaland-Pullus, Christina; Griffith, Jeffrey K

    2006-01-01

    ...: prognosis and diagnosis. Several tools are being used to investigate this effect, specifically the assessment of telomere length, allelic imbalance, and methylation status, all markers of genomic instability...

  19. Evaluation of Genomic Instability in the Abnormal Prostate

    National Research Council Canada - National Science Library

    Haaland-Pullus, Christina; Griffth, Jeffrey K

    2008-01-01

    ...: prognosis and diagnosis. Several tools are being used to investigate this effect, specifically the assessment of telomere length, allelic imbalance, and methylation status, all markers of genomic instability...

  20. Study of genomic instability induced by low dose ionizing radiation

    International Nuclear Information System (INIS)

    Seoane, A.; Crudeli, C.; Dulout, F.

    2006-01-01

    The crews of commercial flights and services staff of radiology and radiotherapy from hospitals are exposed to low doses of ionizing radiation. Genomic instability includes those adverse effects observed in cells, several generations after the exposure occurred. The purpose of this study was to analyze the occurrence of genomic instability by very low doses of ionizing radiation [es

  1. Role of oxidative DNA damage in genome instability and cancer

    International Nuclear Information System (INIS)

    Bignami, M.; Kunkel, T.

    2009-01-01

    Inactivation of mismatch repair (MMR) is associated with a dramatic genomic instability that is observed experimentally as a mutator phenotype and micro satellite instability (MSI). It has been implicit that the massive genetic instability in MMR defective cells simply reflects the accumulation of spontaneous DNA polymerase errors during DNA replication. We recently identified oxidation damage, a common threat to DNA integrity to which purines are very susceptible, as an important cofactor in this genetic instability

  2. Computer modelling of radiation-induced bystander effect

    International Nuclear Information System (INIS)

    Khvostunov, Igor K.; Nikjoo, Hooshang

    2002-01-01

    Radiation-induced genomic instability and bystander effects are now well established consequences of exposure of living cells to ionising radiation. It has been observed that cells not directly hit by radiation tracks may still exhibit radiation effects. We present a quantitative modelling of the radiation-induced bystander effect based on a diffusion model of spreading the bystander signal. The model assumes the bystander factor to be a protein of low molecular weight, given out by the hit cell, diffusing in the medium and reacting with non-hit cells. The model calculations successfully predict the results of cell survival in an irradiated conditioned medium. The model predicts the shape of dose-effect relationship for cell survival and oncogenic transformation induced by broad-beam and micro-beam irradiation by alpha-particles. (author)

  3. Radiation-induced genomic instability is associated with DNA methylation changes in cultured human keratinocytes

    International Nuclear Information System (INIS)

    Kaup, Sahana; Grandjean, Valerie; Mukherjee, Rajarshi; Kapoor, Aparna; Keyes, Edward; Seymour, Colin B.; Mothersill, Carmel E.; Schofield, Paul N.

    2006-01-01

    The mechanism by which radiation-induced genomic instability is initiated, propagated and effected is currently under intense scrutiny. We have investigated the potential role of altered genomic methylation patterns in the cellular response to irradiation and have found evidence for widespread dysregulation of CpG methylation persisting up to 20 population doublings post-irradiation. Similar effects are seen with cells treated with medium from irradiated cells (the 'bystander effect') rather than subjected to direct irradiation. Using an arbitrarily primed methylation sensitive PCR screening method we have demonstrated that irradiation causes reproducible alterations in the methylation profile of a human keratinocyte cell line, HPV-G, and have further characterised one of these sequences as being a member of a retrotransposon element derived sequence family on chromosome 7; MLT1A. Multiple changes were also detected in the screen, which indicate that although the response of cells is predominantly hypermethylation, specific hypomethylation occurs as well. Sequence specific changes are also reported in the methylation of the pericentromeric SAT2 satellite sequence. This is the first demonstration that irradiation results in the induction of heritable methylation changes in mammalian cells, and provides a link between the various non-radiological instigators of genomic instability, the perpetuation of the unstable state and several of its manifestations

  4. Bystander effects and their implications for clinical radiotherapy

    International Nuclear Information System (INIS)

    Munro, Alastair J

    2009-01-01

    Radiation-induced bystander effects are defined as those biological effects expressed, after irradiation, by cells whose nuclei have not been directly irradiated. Radiation oncologists are only gradually beginning to appreciate the clinical relevance of radiation-induced bystander effects and associated phenomena: adaptive responses, genomic instability and abscopal effects. Incorporating bystander effects into the science underpinning clinical radiotherapy will involve moving beyond simple mechanistic models and towards a more systems-based approach. It is, given the protean nature of bystander effects, difficult to devise a coherent research strategy to investigate the clinical impact and relevance of bystander phenomena. Epidemiological approaches will be required, the traditional research models based on randomised controlled trials are unlikely to be adequate for the task. Any consideration of bystander effects challenges not only clinicians' preconceptions concerning the effects of radiation on tumours and normal tissues but also their ingenuity. This review covers, from a clinical perspective, the issues and problems associated with radiation-induced bystander effects.

  5. Breast tumor copy number aberration phenotypes and genomic instability

    International Nuclear Information System (INIS)

    Fridlyand, Jane; Jain, Ajay N; McLennan, Jane; Ziegler, John; Chin, Koei; Devries, Sandy; Feiler, Heidi; Gray, Joe W; Waldman, Frederic; Pinkel, Daniel; Albertson, Donna G; Snijders, Antoine M; Ylstra, Bauke; Li, Hua; Olshen, Adam; Segraves, Richard; Dairkee, Shanaz; Tokuyasu, Taku; Ljung, Britt Marie

    2006-01-01

    Genomic DNA copy number aberrations are frequent in solid tumors, although the underlying causes of chromosomal instability in tumors remain obscure. Genes likely to have genomic instability phenotypes when mutated (e.g. those involved in mitosis, replication, repair, and telomeres) are rarely mutated in chromosomally unstable sporadic tumors, even though such mutations are associated with some heritable cancer prone syndromes. We applied array comparative genomic hybridization (CGH) to the analysis of breast tumors. The variation in the levels of genomic instability amongst tumors prompted us to investigate whether alterations in processes/genes involved in maintenance and/or manipulation of the genome were associated with particular types of genomic instability. We discriminated three breast tumor subtypes based on genomic DNA copy number alterations. The subtypes varied with respect to level of genomic instability. We find that shorter telomeres and altered telomere related gene expression are associated with amplification, implicating telomere attrition as a promoter of this type of aberration in breast cancer. On the other hand, the numbers of chromosomal alterations, particularly low level changes, are associated with altered expression of genes in other functional classes (mitosis, cell cycle, DNA replication and repair). Further, although loss of function instability phenotypes have been demonstrated for many of the genes in model systems, we observed enhanced expression of most genes in tumors, indicating that over expression, rather than deficiency underlies instability. Many of the genes associated with higher frequency of copy number aberrations are direct targets of E2F, supporting the hypothesis that deregulation of the Rb pathway is a major contributor to chromosomal instability in breast tumors. These observations are consistent with failure to find mutations in sporadic tumors in genes that have roles in maintenance or manipulation of the genome

  6. Genomic instability--an evolving hallmark of cancer.

    Science.gov (United States)

    Negrini, Simona; Gorgoulis, Vassilis G; Halazonetis, Thanos D

    2010-03-01

    Genomic instability is a characteristic of most cancers. In hereditary cancers, genomic instability results from mutations in DNA repair genes and drives cancer development, as predicted by the mutator hypothesis. In sporadic (non-hereditary) cancers the molecular basis of genomic instability remains unclear, but recent high-throughput sequencing studies suggest that mutations in DNA repair genes are infrequent before therapy, arguing against the mutator hypothesis for these cancers. Instead, the mutation patterns of the tumour suppressor TP53 (which encodes p53), ataxia telangiectasia mutated (ATM) and cyclin-dependent kinase inhibitor 2A (CDKN2A; which encodes p16INK4A and p14ARF) support the oncogene-induced DNA replication stress model, which attributes genomic instability and TP53 and ATM mutations to oncogene-induced DNA damage.

  7. Detection of genomic instability in hypospadias patients by random ...

    African Journals Online (AJOL)

    DIRECTOR

    2011-05-16

    May 16, 2011 ... organism including bacteria (Sahoo et al., 2010), fungi. (Motlagh and Anvari ... technique that detects genomic alteration correlated with human tumor is .... chromosomal instability among hypospadias patients. REFERENCES.

  8. No significant level of inheritable interchromosomal aberrations in the progeny of bystander primary human fibroblasts after alpha particle irradiation

    Science.gov (United States)

    Hu, Burong; Zhu, Jiayun; Zhou, Hongning; Hei, Tom K.

    2013-02-01

    A major concern for bystander effects is the probability that normal healthy cells adjacent to the irradiated cells become genomically unstable and undergo further carcinogenesis after therapeutic irradiation or space mission where astronauts are exposed to low dose of heavy ions. Genomic instability is a hallmark of cancer cells. In the present study, two irradiation protocols were performed in order to ensure pure populations of bystander cells and the genomic instability in their progeny were investigated. After irradiation, chromosomal aberrations of cells were analyzed at designated time points using G2 phase premature chromosome condensation (G2-PCC) coupled with Giemsa staining and with multiplex fluorescent in situ hybridization (mFISH). Our Giemsa staining assay demonstrated that elevated yields of chromatid breaks were induced in the progeny of pure bystander primary fibroblasts up to 20 days after irradiation. mFISH assay showed no significant level of inheritable interchromosomal aberrations were induced in the progeny of the bystander cell groups, while the fractions of gross aberrations (chromatid breaks or chromosomal breaks) significantly increased in some bystander cell groups. These results suggest that genomic instability occurred in the progeny of the irradiation associated bystander normal fibroblasts exclude the inheritable interchromosomal aberration.

  9. Role of Reactive Oxygen Species and Nitric Oxide in Mediating Chemotherapeutic Drug Induced Bystander Response in Human Cancer Cells Exposed In-Vitro

    Science.gov (United States)

    Chinnadurai, Mani; Rao, Bhavna S; Deepika, Ramasamy; Paul, Solomon F.D.; Venkatachalam, Perumal

    2012-01-01

    Background The intention of cancer chemotherapy is to control the growth of cancer cells using chemical agents. However, the occurrence of second malignancies has raised concerns, leading to re-evaluation of the current strategy in use for chemotherapeutic agents. Although the mechanisms involved in second malignancy remain ambiguous, therapeutic-agent-induced non-DNA targeted effects like bystander response and genomic instability cannot be eliminated completely. Hence, Bleomycin (BLM) and Neocarzinostatin (NCS), chemotherapeutic drugs with a mode of action similar to ionizing radiation, were used to study the mechanism of bystander response in human cancer cells (A549, CCRF-CEM and HL-60) by employing co-culture methodology. Methods Bystander effect was quantified using micronucleus (MN) assay and in-situ immunofluorescence(γH2AX assay).The role of reactive oxygen species (ROS) and nitric oxide (NO) in mediating the bystander response was explored by pre-treating bystander cells with dimethylsulphoxide (DMSO) and C-PTIO respectively. Results Bystander response was observed only in CCRF-CEM and A549 cells (P bystander response on treatment with DMSO, suggests that ROS has a more significant role in mediating the bystander response.Since the possibility of the ROS and NO in mediating these bystander effect was confirmed, mechanistic control of these signaling molecules could either reduce radiation damage and potential carcinogenicity of normal tissues (by reducing bystander signaling) or maximize cell sterilization during chemotherapy (by amplifying bystander responses in tumors). PMID:29147282

  10. In Vivo Bystander Effect: Cranial X-Irradiation Leads to Elevated DNA Damage, Altered Cellular Proliferation and Apoptosis, and Increased p53 Levels in Shielded Spleen

    International Nuclear Information System (INIS)

    Koturbash, Igor; Loree, Jonathan; Kutanzi, Kristy; Koganow, Clayton; Pogribny, Igor; Kovalchuk, Olga

    2008-01-01

    Purpose: It is well accepted that irradiated cells may 'forward' genome instability to nonirradiated neighboring cells, giving rise to the 'bystander effect' phenomenon. Although bystander effects were well studied by using cell cultures, data for somatic bystander effects in vivo are relatively scarce. Methods and Materials: We set out to analyze the existence and molecular nature of bystander effects in a radiation target-organ spleen by using a mouse model. The animal's head was exposed to X-rays while the remainder of the body was completely protected by a medical-grade shield. Using immunohistochemistry, we addressed levels of DNA damage, cellular proliferation, apoptosis, and p53 protein in the spleen of control animals and completely exposed and head-exposed/body bystander animals. Results: We found that localized head radiation exposure led to the induction of bystander effects in the lead-shielded distant spleen tissue. Namely, cranial irradiation led to increased levels of DNA damage and p53 expression and also altered levels of cellular proliferation and apoptosis in bystander spleen tissue. The observed bystander changes were not caused by radiation scattering and were observed in two different mouse strains; C57BL/6 and BALB/c. Conclusion: Our study proves that bystander effects occur in the distant somatic organs on localized exposures. Additional studies are required to characterize the nature of an enigmatic bystander signal and analyze the long-term persistence of these effects and possible contribution of radiation-induced bystander effects to secondary radiation carcinogenesis

  11. Genome instability in Lactobacillus rhamnosus GG

    NARCIS (Netherlands)

    Sybesma, W.; Molenaar, D.; IJcken, W. van; Venema, K.; Korta, R.

    2013-01-01

    We describe here a comparative genome analysis of three dairy product isolates of Lactobacillus rhamnosus GG (LGG) and the ATCC 53103 reference strain to the published genome sequence of L. rhamnosus GG. The analysis showed that in two of three isolates, major DNA segments were missing from the

  12. Tolerance of Whole-Genome Doubling Propagates Chromosomal Instability and Accelerates Cancer Genome Evolution

    DEFF Research Database (Denmark)

    Dewhurst, Sally M.; McGranahan, Nicholas; Burrell, Rebecca A.

    2014-01-01

    The contribution of whole-genome doubling to chromosomal instability (CIN) and tumor evolution is unclear. We use long-term culture of isogenic tetraploid cells from a stable diploid colon cancer progenitor to investigate how a genome-doubling event affects genome stability over time. Rare cells...

  13. Causation of cancer by ionizing radiation and genomic instability

    International Nuclear Information System (INIS)

    Streffer, Christian

    2013-01-01

    The causation of cancer by ionizing radiation has been shown in many epidemiological (with exposed humans) as well as experimental studies with mammals especially mice but also rats, dogs and monkeys. Risk values have been determined in medium radiation dose ranges (∼100 to 2,000 mSv). However, in the low dose range (<100 mSv) the situation is unclear and unsolved up to now. A better knowledge of the mechanisms for the development of cancer in humans over decades after low to medium radiation exposures is necessary for the understanding of the open questions. An increase of chromosomal aberrations and other genetic changes have been frequently observed directly after radiation exposures in many cell systems including human cells. However, in 1989 it was found that an increase of genomic instability occurred after irradiation of mouse zygotes in the fibroblasts of the neonates developing from the irradiated zygotes. That means genomic instability developed many cell generations later in cells which never had been exposed to various qualities of ionizing radiations in vivo and any treatment and secondary cancers developed in photon irradiated M.Hodgkin patients preferentially in those patients who showed a comparatively high genomic instability in their lymphocytes. Since several decades it has been experienced that certain cancer patients show an extremely high radio-sensitivity. This clinical observation has been confirmed by experimental investigations with cells of such patients. It has been proven that this increased radio-sensitivity is due to genetic mutations. A number of syndromes could be defined on such a genetic basis like ataxia telangiectasia, bloom's syndrome, fanconi anemia, retinoblasoma and others. In all these syndromes mutations occur in genes which are to regulation of the cell cycle or DNA repair (preferentially repair of DSBs). These patients with an increased radio-sensitivity frequently develop cancer - very often lymphoma - and they also

  14. Myc-dependent genome instability and lifespan in Drosophila.

    Directory of Open Access Journals (Sweden)

    Christina Greer

    Full Text Available The Myc family of transcription factors are key regulators of cell growth and proliferation that are dysregulated in a large number of human cancers. When overexpressed, Myc family proteins also cause genomic instability, a hallmark of both transformed and aging cells. Using an in vivo lacZ mutation reporter, we show that overexpression of Myc in Drosophila increases the frequency of large genome rearrangements associated with erroneous repair of DNA double-strand breaks (DSBs. In addition, we find that overexpression of Myc shortens adult lifespan and, conversely, that Myc haploinsufficiency reduces mutation load and extends lifespan. Our data provide the first evidence that Myc may act as a pro-aging factor, possibly through its ability to greatly increase genome instability.

  15. The role of radiation types and dose in induced genomic instability

    International Nuclear Information System (INIS)

    Kadhim Munira, A.

    2007-01-01

    Complete text of publication follows. Genomic Instability (GI) is defined as long-term alterations induced by low-dose exposure to a variety of genotoxic agents in mammalian cells that act to increase the 'apparent' spontaneous mutation frequency.GI is a hallmark of tumorigenic progression and is observed in the progeny of irradiated and bystander cells as the delayed and stochastic appearance of de novo chromosomal aberrations, gene mutations and delayed lethal mutations both in vitro and in vivo. It occurs at a frequency several orders of magnitude greater than would be expected for mutation in a single gene, implying that GI is a multigenic phenomenon. The expression of GI can be influenced by genotype, cell type and radiation quality; however the underlying mechanisms are not fully understood. While several studies have demonstrated GI induction by high and low LET radiation, our work on human and mouse primary cell systems has shown significant differences in the capacity to induce GI and the spectrum of alterations depending on LET. These differences might be attributed to differences in radiation track structure, radiation dose and radiation exposure regime (distribution of hit and un hit cells). In this presentation I shall review the role of radiation quality; describe the possible mechanisms underlining the observed differences between radiation type and present results of experiments demonstrating that the dose of low LET radiation might be the most significant factor in determining the role of radiation type in the induction of GI.

  16. Bystander Effect Induced by UV Radiation; why should we be interested? 

    Directory of Open Access Journals (Sweden)

    Maria Widel

    2012-11-01

    Full Text Available The bystander effect, whose essence is an interaction of cells directly subjected to radiation with adjacent non-subjected cells, via molecular signals, is an important component of ionizing radiation action. However, knowledge of the bystander effect in the case of ultraviolet (UV radiation is quite limited. Reactive oxygen and nitrogen species generated by UV in exposed cells induce bystander effects in non-exposed cells, such as reduction in clonogenic cell survival and delayed cell death, oxidative DNA damage and gene mutations, induction of micronuclei, lipid peroxidation and apoptosis. Although the bystander effect after UV radiation has been recognized in cell culture systems, its occurrence in vivo has not been studied. However, solar UV radiation, which is the main source of UV in the environment, may induce in human dermal tissue an inflammatory response and immune suppression, events which can be considered as bystander effects of UV radiation. The oxidative damage to DNA, genomic instability and the inflammatory response may lead to carcinogenesis. UV radiation is considered one of the important etiologic factors for skin cancers, basal- and squamous-cell carcinomas and malignant melanoma. Based on the mechanisms of actions it seems that the UV-induced bystander effect can have some impact on skin damage (carcinogenesis?, and probably on cells of other tissues. The paper reviews the existing data about the UV-induced bystander effect and discusses a possible implication of this phenomenon for health risk. 

  17. Introns Protect Eukaryotic Genomes from Transcription-Associated Genetic Instability.

    Science.gov (United States)

    Bonnet, Amandine; Grosso, Ana R; Elkaoutari, Abdessamad; Coleno, Emeline; Presle, Adrien; Sridhara, Sreerama C; Janbon, Guilhem; Géli, Vincent; de Almeida, Sérgio F; Palancade, Benoit

    2017-08-17

    Transcription is a source of genetic instability that can notably result from the formation of genotoxic DNA:RNA hybrids, or R-loops, between the nascent mRNA and its template. Here we report an unexpected function for introns in counteracting R-loop accumulation in eukaryotic genomes. Deletion of endogenous introns increases R-loop formation, while insertion of an intron into an intronless gene suppresses R-loop accumulation and its deleterious impact on transcription and recombination in yeast. Recruitment of the spliceosome onto the mRNA, but not splicing per se, is shown to be critical to attenuate R-loop formation and transcription-associated genetic instability. Genome-wide analyses in a number of distant species differing in their intron content, including human, further revealed that intron-containing genes and the intron-richest genomes are best protected against R-loop accumulation and subsequent genetic instability. Our results thereby provide a possible rationale for the conservation of introns throughout the eukaryotic lineage. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Up-regulation of ROS by mitochondria-dependent bystander signaling contributes to genotoxicity of bystander effects

    International Nuclear Information System (INIS)

    Chen Shaopeng; Zhao Ye; Zhao Guoping; Han Wei; Bao Lingzhi; Yu, K.N.; Wu Lijun

    2009-01-01

    Genomic instability can be observed in bystander cells. However, the underlying mechanism(s) is still relatively unclear. In a previous study, we found that irradiated cells released mitochondria-dependent intracellular factor(s) which could lead to bystander γ-H2AX induction. In this paper, we used normal (ρ + ) and mtDNA-depleted (ρ 0 ) human-hamster hybrid cells to investigate mitochondrial effects on the genotoxicity in bystander effect through medium transfer experiments. Through the detection of DNA double-strand breaks with γ-H2AX, we found that the fraction of γ-H2AX positive cells changed with time when irradiation conditioned cell medium (ICCM) were harvested. ICCM harvested from irradiated ρ + cells at 10 min post-irradiation (ρ + ICCM 10min ) caused larger increases of bystander γ-H2AX induction comparing to ρ 0 ICCM 10min , which only caused a slight increase of bystander γ-H2AX induction. The ρ + ICCM 10min could also result in the up-regulation of ROS production (increased by 35% at 10 min), while there was no significant increase in cells treated with ρ 0 ICCM 10min . We treated cells with dimethyl sulfoxide (DMSO), the scavenger of ROS, and quenched γ-H2AX induction by ρ + ICCM. Furthermore, after the medium had been transferred and the cells were continuously cultured for 7 days, we found significantly increased CD59 - gene loci mutation (increased by 45.9%) and delayed cell death in the progeny of ρ + ICCM-treated bystander cells. In conclusion, the work presented here suggested that up-regulation of the mitochondria-dependent ROS might be very important in mediating genotoxicity of bystander effects.

  19. Up-regulation of ROS by mitochondria-dependent bystander signaling contributes to genotoxicity of bystander effects

    Energy Technology Data Exchange (ETDEWEB)

    Chen Shaopeng [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Zhao Ye; Zhao Guoping [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Han Wei [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Bao Lingzhi [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N., E-mail: peter.yu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Wu Lijun, E-mail: ljw@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2009-06-18

    Genomic instability can be observed in bystander cells. However, the underlying mechanism(s) is still relatively unclear. In a previous study, we found that irradiated cells released mitochondria-dependent intracellular factor(s) which could lead to bystander {gamma}-H2AX induction. In this paper, we used normal ({rho}{sup +}) and mtDNA-depleted ({rho}{sup 0}) human-hamster hybrid cells to investigate mitochondrial effects on the genotoxicity in bystander effect through medium transfer experiments. Through the detection of DNA double-strand breaks with {gamma}-H2AX, we found that the fraction of {gamma}-H2AX positive cells changed with time when irradiation conditioned cell medium (ICCM) were harvested. ICCM harvested from irradiated {rho}{sup +} cells at 10 min post-irradiation ({rho}{sup +} ICCM{sub 10min}) caused larger increases of bystander {gamma}-H2AX induction comparing to {rho}{sup 0} ICCM{sub 10min}, which only caused a slight increase of bystander {gamma}-H2AX induction. The {rho}{sup +} ICCM{sub 10min} could also result in the up-regulation of ROS production (increased by 35% at 10 min), while there was no significant increase in cells treated with {rho}{sup 0} ICCM{sub 10min}. We treated cells with dimethyl sulfoxide (DMSO), the scavenger of ROS, and quenched {gamma}-H2AX induction by {rho}{sup +} ICCM. Furthermore, after the medium had been transferred and the cells were continuously cultured for 7 days, we found significantly increased CD59{sup -} gene loci mutation (increased by 45.9%) and delayed cell death in the progeny of {rho}{sup +} ICCM-treated bystander cells. In conclusion, the work presented here suggested that up-regulation of the mitochondria-dependent ROS might be very important in mediating genotoxicity of bystander effects.

  20. Instability of plastid DNA in the nuclear genome.

    Directory of Open Access Journals (Sweden)

    Anna E Sheppard

    2009-01-01

    Full Text Available Functional gene transfer from the plastid (chloroplast and mitochondrial genomes to the nucleus has been an important driving force in eukaryotic evolution. Non-functional DNA transfer is far more frequent, and the frequency of such transfers from the plastid to the nucleus has been determined experimentally in tobacco using transplastomic lines containing, in their plastid genome, a kanamycin resistance gene (neo readymade for nuclear expression. Contrary to expectations, non-Mendelian segregation of the kanamycin resistance phenotype is seen in progeny of some lines in which neo has been transferred to the nuclear genome. Here, we provide a detailed analysis of the instability of kanamycin resistance in nine of these lines, and we show that it is due to deletion of neo. Four lines showed instability with variation between progeny derived from different areas of the same plant, suggesting a loss of neo during somatic cell division. One line showed a consistent reduction in the proportion of kanamycin-resistant progeny, suggesting a loss of neo during meiosis, and the remaining four lines were relatively stable. To avoid genomic enlargement, the high frequency of plastid DNA integration into the nuclear genome necessitates a counterbalancing removal process. This is the first demonstration of such loss involving a high proportion of recent nuclear integrants. We propose that insertion, deletion, and rearrangement of plastid sequences in the nuclear genome are important evolutionary processes in the generation of novel nuclear genes. This work is also relevant in the context of transgenic plant research and crop production, because similar processes to those described here may be involved in the loss of plant transgenes.

  1. Oxidative DNA damage causes mitochondrial genomic instability in Saccharomyces cerevisiae.

    Science.gov (United States)

    Doudican, Nicole A; Song, Binwei; Shadel, Gerald S; Doetsch, Paul W

    2005-06-01

    Mitochondria contain their own genome, the integrity of which is required for normal cellular energy metabolism. Reactive oxygen species (ROS) produced by normal mitochondrial respiration can damage cellular macromolecules, including mitochondrial DNA (mtDNA), and have been implicated in degenerative diseases, cancer, and aging. We developed strategies to elevate mitochondrial oxidative stress by exposure to antimycin and H(2)O(2) or utilizing mutants lacking mitochondrial superoxide dismutase (sod2Delta). Experiments were conducted with strains compromised in mitochondrial base excision repair (ntg1Delta) and oxidative damage resistance (pif1Delta) in order to delineate the relationship between these pathways. We observed enhanced ROS production, resulting in a direct increase in oxidative mtDNA damage and mutagenesis. Repair-deficient mutants exposed to oxidative stress conditions exhibited profound genomic instability. Elimination of Ntg1p and Pif1p resulted in a synergistic corruption of respiratory competency upon exposure to antimycin and H(2)O(2). Mitochondrial genomic integrity was substantially compromised in ntg1Delta pif1Delta sod2Delta strains, since these cells exhibit a total loss of mtDNA. A stable respiration-defective strain, possessing a normal complement of mtDNA damage resistance pathways, exhibited a complete loss of mtDNA upon exposure to antimycin and H(2)O(2). This loss was preventable by Sod2p overexpression. These results provide direct evidence that oxidative mtDNA damage can be a major contributor to mitochondrial genomic instability and demonstrate cooperation of Ntg1p and Pif1p to resist the introduction of lesions into the mitochondrial genome.

  2. BYSTANDER EFFECTS, GENOMIC INSTABILITY, ADAPTIVE RESPONSE AND CANCER RISK ASSESSMENT FOR RADIATION AND CHEMICAL EXPOSURES

    Science.gov (United States)

    There is an increased interest in utilizing mechanistic data in support of the cancer risk assessment process for ionizing radiation and environmental chemical exposures. In this regard the use of biologically based dose-response models is particularly advocated. The aim is to pr...

  3. Bystander deixis

    DEFF Research Database (Denmark)

    Rijkhoff, Jan

    1998-01-01

    The purpose of this contribution is to discuss non-standard speech forms of Romani and other languages in the larger context of bystander deixis, a subcategory of social deixis. First I will propose a three-way classification of instances of bystander deixis and illustrate them with examples from...... Romani and several other languages across the globe. The second part is concerned with the contextual factors that must have a place in a discourse model that wants to be able to handle linguistic manifestations of bystander deixis. Due the fact that Romani has typically been used for in......-group communication, this language presents a particularly rich source of information in the area of secret languages and other forms of bystander deixis. Moreover, as is also made abundantly clear in this volume, many jargons, trade varieties, secret languages and other more or less non-standard speech varieties...

  4. Contribution of bystander effects in radiation induced genotoxicity

    International Nuclear Information System (INIS)

    Zhou, H.; Persaud, R.; Gillispie, J.; Randers-Pehrson, G.; Hei, T.K.; Suzuki, Masao

    2005-01-01

    The controversial use of a linear, no threshold extrapolation model for low dose risk assessment is based on the accepted dogma that the deleterious effects of ionizing radiation such as mutagenesis and carcinogenesis are attributable mainly to direct damage to DNA. However, this extrapolation was challenged by the recent reports on the bystander phenomenon. The bystander effect contributes to this debate by implying that the biological effects of low doses, where not all cells are traversed by a charged particle, are amplified by the transfer of factors to un-irradiated neighbors. This interested phenomenon implies that a linear extrapolation of risks from high to low doses may underestimate rather than over estimate low dose risks. Together with some radiation-induced phenomena such as adaptive response and genomic instability, the radiobiological response at low doses is likely to be a complex interplay among many factors. (author)

  5. p53 protects against genome instability following centriole duplication failure

    Science.gov (United States)

    Lambrus, Bramwell G.; Uetake, Yumi; Clutario, Kevin M.; Daggubati, Vikas; Snyder, Michael; Sluder, Greenfield

    2015-01-01

    Centriole function has been difficult to study because of a lack of specific tools that allow persistent and reversible centriole depletion. Here we combined gene targeting with an auxin-inducible degradation system to achieve rapid, titratable, and reversible control of Polo-like kinase 4 (Plk4), a master regulator of centriole biogenesis. Depletion of Plk4 led to a failure of centriole duplication that produced an irreversible cell cycle arrest within a few divisions. This arrest was not a result of a prolonged mitosis, chromosome segregation errors, or cytokinesis failure. Depleting p53 allowed cells that fail centriole duplication to proliferate indefinitely. Washout of auxin and restoration of endogenous Plk4 levels in cells that lack centrioles led to the penetrant formation of de novo centrioles that gained the ability to organize microtubules and duplicate. In summary, we uncover a p53-dependent surveillance mechanism that protects against genome instability by preventing cell growth after centriole duplication failure. PMID:26150389

  6. Analysis of genomic instability in bronchial cells from uranium miners

    International Nuclear Information System (INIS)

    Neft, R.E.; Belinsky, S.A.; Gilliland, F.D.; Lechner, J.F.

    1994-01-01

    Epidemiological studies show that underground uranium miners have a radon progeny exposure-dependent increased risk for developing lung cancer. The odds ratio for lung cancer in uranium miners increase for all cumulative exposures above 99 Working Level Months. In addition, there is a strong multiplicative effect of cigarette smoking on the development of lung cancer in uranium miners. The purpose of this investigation was to determine whether or not early genetic changes, as indicated by genomic instability, can be detected in bronchial cells from uranium miners. Investigations of this nature may serve as a means of discovering sub-clinical disease and could lead to earlier detection of lung cancer and a better prognosis for the patient

  7. Signaling pathways underpinning the manifestations of ionizing radiation-induced bystander effects.

    Science.gov (United States)

    Hamada, Nobuyuki; Maeda, Munetoshi; Otsuka, Kensuke; Tomita, Masanori

    2011-06-01

    For nearly a century, ionizing radiation has been indispensable to medical diagnosis. Furthermore, various types of electromagnetic and particulate radiation have also been used in cancer therapy. However, the biological mechanism of radiation action remains incompletely understood. In this regard, a rapidly growing body of experimental evidence indicates that radiation exposure induces biological effects in cells whose nucleus has not been irradiated. This phenomenon termed the 'non-targeted effects' challenges the long-held tenet that radiation traversal through the cell nucleus is a prerequisite to elicit genetic damage and biological responses. The non-targeted effects include biological effects in cytoplasm-irradiated cells, bystander effects that arise in non-irradiated cells having received signals from irradiated cells, and genomic instability occurring in the progeny of irradiated cells. Such non-targeted responses are interrelated, and the bystander effect is further related with an adaptive response that manifests itself as the attenuated stressful biological effects of acute high-dose irradiation in cells that have been pre-exposed to low-dose or low-dose-rate radiation. This paper reviews the current body of knowledge about the bystander effect with emphasis on experimental approaches, in vitro and in vivo manifestations, radiation quality dependence, temporal and spatial dependence, proposed mechanisms, and clinical implications. Relations of bystander responses with the effects in cytoplasm-irradiated cells, genomic instability and adaptive response will also be briefly discussed.

  8. Ectopic Expression of Testis Germ Cell Proteins in Cancer and Its Potential Role in Genomic Instability

    Directory of Open Access Journals (Sweden)

    Aaraby Yoheswaran Nielsen

    2016-06-01

    Full Text Available Genomic instability is a hallmark of human cancer and an enabling factor for the genetic alterations that drive cancer development. The processes involved in genomic instability resemble those of meiosis, where genetic material is interchanged between homologous chromosomes. In most types of human cancer, epigenetic changes, including hypomethylation of gene promoters, lead to the ectopic expression of a large number of proteins normally restricted to the germ cells of the testis. Due to the similarities between meiosis and genomic instability, it has been proposed that activation of meiotic programs may drive genomic instability in cancer cells. Some germ cell proteins with ectopic expression in cancer cells indeed seem to promote genomic instability, while others reduce polyploidy and maintain mitotic fidelity. Furthermore, oncogenic germ cell proteins may indirectly contribute to genomic instability through induction of replication stress, similar to classic oncogenes. Thus, current evidence suggests that testis germ cell proteins are implicated in cancer development by regulating genomic instability during tumorigenesis, and these proteins therefore represent promising targets for novel therapeutic strategies.

  9. p53-Dependent suppression of genome instability in germ cells

    Energy Technology Data Exchange (ETDEWEB)

    Otozai, Shinji [Department of Otorhinolaryngology and Head and Neck Surgery, Osaka University School of Medicine, Osaka 565-0871 (Japan); Ishikawa-Fujiwara, Tomoko [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Oda, Shoji [Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8562 (Japan); Kamei, Yasuhiro [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan); Ryo, Haruko [Nomura Project, National Institute of Biomedical Innovation, Osaka 565-0085 (Japan); Sato, Ayuko [Department of Pathology, Hyogo College of Medicine, Hyogo 663-8501 (Japan); Nomura, Taisei [Nomura Project, National Institute of Biomedical Innovation, Osaka 565-0085 (Japan); Mitani, Hiroshi [Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba 277-8562 (Japan); Tsujimura, Tohru [Department of Pathology, Hyogo College of Medicine, Hyogo 663-8501 (Japan); Inohara, Hidenori [Department of Otorhinolaryngology and Head and Neck Surgery, Osaka University School of Medicine, Osaka 565-0871 (Japan); Todo, Takeshi, E-mail: todo@radbio.med.osaka-u.ac.jp [Department of Radiation Biology and Medical Genetics, Graduate School of Medicine, Osaka University, B4, 2-2 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2014-02-15

    Highlights: • Radiation-induced microsatellite instability (MSI) was investigated in medaka fish. • msh2{sup −/−} fish had a high frequency of spontaneous MSI. • p53{sup −/−} fish had a high frequency of radiation-induced MSI. • p53 and msh2 suppress MSI by different pathways: mismatch removal and apoptosis. - Abstract: Radiation increases mutation frequencies at tandem repeat loci. Germline mutations in γ-ray-irradiated medaka fish (Oryzias latipes) were studied, focusing on the microsatellite loci. Mismatch-repair genes suppress microsatellite mutation by directly removing altered sequences at the nucleotide level, whereas the p53 gene suppresses genetic alterations by eliminating damaged cells. The contribution of these two defense mechanisms to radiation-induced microsatellite instability was addressed. The spontaneous mutation frequency was significantly higher in msh2{sup −/−} males than in wild-type fish, whereas there was no difference in the frequency of radiation-induced mutations between msh2{sup −/−} and wild-type fish. By contrast, irradiated p53{sup −/−} fish exhibited markedly increased mutation frequencies, whereas their spontaneous mutation frequency was the same as that of wild-type fish. In the spermatogonia of the testis, radiation induced a high level of apoptosis both in wild-type and msh2{sup −/−} fish, but negligible levels in p53{sup −/−} fish. The results demonstrate that the msh2 and p53 genes protect genome integrity against spontaneous and radiation-induced mutation by two different pathways: direct removal of mismatches and elimination of damaged cells.

  10. p53-Dependent suppression of genome instability in germ cells

    International Nuclear Information System (INIS)

    Otozai, Shinji; Ishikawa-Fujiwara, Tomoko; Oda, Shoji; Kamei, Yasuhiro; Ryo, Haruko; Sato, Ayuko; Nomura, Taisei; Mitani, Hiroshi; Tsujimura, Tohru; Inohara, Hidenori; Todo, Takeshi

    2014-01-01

    Highlights: • Radiation-induced microsatellite instability (MSI) was investigated in medaka fish. • msh2 −/− fish had a high frequency of spontaneous MSI. • p53 −/− fish had a high frequency of radiation-induced MSI. • p53 and msh2 suppress MSI by different pathways: mismatch removal and apoptosis. - Abstract: Radiation increases mutation frequencies at tandem repeat loci. Germline mutations in γ-ray-irradiated medaka fish (Oryzias latipes) were studied, focusing on the microsatellite loci. Mismatch-repair genes suppress microsatellite mutation by directly removing altered sequences at the nucleotide level, whereas the p53 gene suppresses genetic alterations by eliminating damaged cells. The contribution of these two defense mechanisms to radiation-induced microsatellite instability was addressed. The spontaneous mutation frequency was significantly higher in msh2 −/− males than in wild-type fish, whereas there was no difference in the frequency of radiation-induced mutations between msh2 −/− and wild-type fish. By contrast, irradiated p53 −/− fish exhibited markedly increased mutation frequencies, whereas their spontaneous mutation frequency was the same as that of wild-type fish. In the spermatogonia of the testis, radiation induced a high level of apoptosis both in wild-type and msh2 −/− fish, but negligible levels in p53 −/− fish. The results demonstrate that the msh2 and p53 genes protect genome integrity against spontaneous and radiation-induced mutation by two different pathways: direct removal of mismatches and elimination of damaged cells

  11. Ionizing radiation induced genomic instability and its relation to radiation carcinogenesis

    International Nuclear Information System (INIS)

    Wang Zhongwen

    2000-01-01

    There are widespread testimonies that the genomic instability induced by ionizing irradiation exits in mammal and its vitro cells. Genomic instability can enhance the frequency of genetic changes among the progeny of the original irradiated cells. In the radiation-leukemogenesis, there is no significant difference between controls and CBA/H mouses of PPI (preconception patent irradiation), but the offsprings of the PPI recipients show a different character (shorter latent period and higher incidence) after an extra γ-radiation. The radiation-induced genomic instability may get the genome on the verge of mutation and lead to carcinogens following mutation of some critical genes. The genomic instability, as the early event of initiation of carcinomas, may be play a specific or unique role

  12. Air pollution and genomic instability: The role of particulate matter in lung carcinogenesis

    International Nuclear Information System (INIS)

    Santibáñez-Andrade, Miguel; Quezada-Maldonado, Ericka Marel; Osornio-Vargas, Álvaro; Sánchez-Pérez, Yesennia; García-Cuellar, Claudia M.

    2017-01-01

    In this review, we summarize and discuss the evidence regarding the interaction between air pollution, especially particulate matter (PM), and genomic instability. PM has been widely studied in the context of several diseases, and its role in lung carcinogenesis gained relevance due to an increase in cancer cases for which smoking does not seem to represent the main risk factor. According to epidemiological and toxicological evidence, PM acts as a carcinogenic factor in humans, inducing high rates of genomic alterations. Here, we discuss not only how PM is capable of inducing genomic instability during the carcinogenic process but also how our genetic background influences the response to the sources of damage. - Highlights: • Air pollution represents a worldwide problem with impact on human health. • Particulate matter (PM) has a recognized carcinogenic potential in humans. • Lung cancer susceptibility depends on gene-environment interactions. • Epidemiological and experimental evidence links PM exposure to genomic instability. • PM and genomic instability are co-dependent factors during cancer continuum. - We summarize the association between particulate matter (a component of air pollution) and genomic instability as well as discuss how new strategies to study the impact of air pollution on genomic instability and lung-cancer development could improve our understanding of the lung-cancer genome.

  13. Role of nitric oxide in the radiation-induced bystander effect.

    Science.gov (United States)

    Yakovlev, Vasily A

    2015-12-01

    Cells that are not irradiated but are affected by "stress signal factors" released from irradiated cells are called bystander cells. These cells, as well as directly irradiated ones, express DNA damage-related proteins and display excess DNA damage, chromosome aberrations, mutations, and malignant transformation. This phenomenon has been studied widely in the past 20 years, since its first description by Nagasawa and Little in 1992, and is known as the radiation-induced bystander effect (RIBE). Several factors have been identified as playing a role in the bystander response. This review will focus on one of them, nitric oxide (NO), and its role in the stimulation and propagation of RIBE. The hydrophobic properties of NO, which permit its diffusion through the cytoplasm and plasma membranes, allow this signaling molecule to easily spread from irradiated cells to bystander cells without the involvement of gap junction intercellular communication. NO produced in irradiated tissues mediates cellular regulation through posttranslational modification of a number of regulatory proteins. The best studied of these modifications are S-nitrosylation (reversible oxidation of cysteine) and tyrosine nitration. These modifications can up- or down-regulate the functions of many proteins modulating different NO-dependent effects. These NO-dependent effects include the stimulation of genomic instability (GI) and the accumulation of DNA errors in bystander cells without direct DNA damage. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Dioxin induces genomic instability in mouse embryonic fibroblasts.

    Directory of Open Access Journals (Sweden)

    Merja Korkalainen

    Full Text Available Ionizing radiation and certain other exposures have been shown to induce genomic instability (GI, i.e., delayed genetic damage observed many cell generations later in the progeny of the exposed cells. The aim of this study was to investigate induction of GI by a nongenotoxic carcinogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD. Mouse embryonic fibroblasts (C3H10T1/2 were exposed to 1, 10 or 100 nM TCDD for 2 days. Micronuclei (MN and expression of selected cancer-related genes were assayed both immediately and at a delayed point in time (8 days. For comparison, similar experiments were done with cadmium, a known genotoxic agent. TCDD treatment induced an elevated frequency of MN at 8 days, but not directly after the exposure. TCDD-induced alterations in gene expression were also mostly delayed, with more changes observed at 8 days than at 2 days. Exposure to cadmium produced an opposite pattern of responses, with pronounced effects immediately after exposure but no increase in MN and few gene expression changes at 8 days. Although all responses to TCDD alone were delayed, menadione-induced DNA damage (measured by the Comet assay, was found to be increased directly after a 2-day TCDD exposure, indicating that the stability of the genome was compromised already at this time point. The results suggested a flat dose-response relationship consistent with dose-response data reported for radiation-induced GI. These findings indicate that TCDD, although not directly genotoxic, induces GI, which is associated with impaired DNA damage response.

  15. Causes of genome instability: the effect of low dose chemical exposures in modern society

    Science.gov (United States)

    Langie, Sabine A.S.; Koppen, Gudrun; Desaulniers, Daniel; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Azqueta, Amaya; Bisson, William H.; Brown, Dustin; Brunborg, Gunnar; Charles, Amelia K.; Chen, Tao; Colacci, Annamaria; Darroudi, Firouz; Forte, Stefano; Gonzalez, Laetitia; Hamid, Roslida A.; Knudsen, Lisbeth E.; Leyns, Luc; Lopez de Cerain Salsamendi, Adela; Memeo, Lorenzo; Mondello, Chiara; Mothersill, Carmel; Olsen, Ann-Karin; Pavanello, Sofia; Raju, Jayadev; Rojas, Emilio; Roy, Rabindra; Ryan, Elizabeth; Ostrosky-Wegman, Patricia; Salem, Hosni K.; Scovassi, Ivana; Singh, Neetu; Vaccari, Monica; Van Schooten, Frederik J.; Valverde, Mahara; Woodrick, Jordan; Zhang, Luoping; van Larebeke, Nik; Kirsch-Volders, Micheline; Collins, Andrew R.

    2015-01-01

    Genome instability is a prerequisite for the development of cancer. It occurs when genome maintenance systems fail to safeguard the genome’s integrity, whether as a consequence of inherited defects or induced via exposure to environmental agents (chemicals, biological agents and radiation). Thus, genome instability can be defined as an enhanced tendency for the genome to acquire mutations; ranging from changes to the nucleotide sequence to chromosomal gain, rearrangements or loss. This review raises the hypothesis that in addition to known human carcinogens, exposure to low dose of other chemicals present in our modern society could contribute to carcinogenesis by indirectly affecting genome stability. The selected chemicals with their mechanisms of action proposed to indirectly contribute to genome instability are: heavy metals (DNA repair, epigenetic modification, DNA damage signaling, telomere length), acrylamide (DNA repair, chromosome segregation), bisphenol A (epigenetic modification, DNA damage signaling, mitochondrial function, chromosome segregation), benomyl (chromosome segregation), quinones (epigenetic modification) and nano-sized particles (epigenetic pathways, mitochondrial function, chromosome segregation, telomere length). The purpose of this review is to describe the crucial aspects of genome instability, to outline the ways in which environmental chemicals can affect this cancer hallmark and to identify candidate chemicals for further study. The overall aim is to make scientists aware of the increasing need to unravel the underlying mechanisms via which chemicals at low doses can induce genome instability and thus promote carcinogenesis. PMID:26106144

  16. Profiles of Genomic Instability in High-Grade Serous Ovarian Cancer Predict Treatment Outcome

    DEFF Research Database (Denmark)

    Wang, Zhigang C.; Birkbak, Nicolai Juul; Culhane, Aedín C.

    2012-01-01

    Purpose: High-grade serous cancer (HGSC) is the most common cancer of the ovary and is characterized by chromosomal instability. Defects in homologous recombination repair (HRR) are associated with genomic instability in HGSC, and are exploited by therapy targeting DNA repair. Defective HRR cause...

  17. Genomic instability in human actinic keratosis and squamous cell carcinoma

    Science.gov (United States)

    Cabral, Luciana Sanches; Neto, Cyro Festa; Sanches, José A; Ruiz, Itamar R G

    2011-01-01

    OBJECTIVE: To compare the repetitive DNA patterns of human actinic keratoses and squamous cell carcinomas to determine the genetic alterations that are associated with malignant transformation. INTRODUCTION: Cancer cells are prone to genomic instability, which is often due to DNA polymerase slippage during the replication of repetitive DNA and to mutations in the DNA repair genes. The progression of benign actinic keratoses to malignant squamous cell carcinomas has been proposed by several authors. MATERIAL AND METHODS: Eight actinic keratoses and 24 squamous cell carcinomas (SCC), which were pair-matched to adjacent skin tissues and/or leucocytes, were studied. The presence of microsatellite instability (MSI) and the loss of heterozygosity (LOH) in chromosomes 6 and 9 were investigated using nine PCR primer pairs. Random Amplified Polymorphic DNA patterns were also evaluated using eight primers. RESULTS: MSI was detected in two (D6S251, D9S50) of the eight actinic keratosis patients. Among the 8 patients who had squamous cell carcinoma-I and provided informative results, a single patient exhibited two LOH (D6S251, D9S287) and two instances of MSI (D9S180, D9S280). Two LOH and one example of MSI (D6S251) were detected in three out of the 10 patients with squamous cell carcinoma-II. Among the four patients with squamous cell carcinoma-III, one patient displayed three MSIs (D6S251, D6S252, and D9S180) and another patient exhibited an MSI (D9S280). The altered random amplified polymorphic DNA ranged from 70% actinic keratoses, 76% squamous cell carcinoma-I, and 90% squamous cell carcinoma-II, to 100% squamous cell carcinoma-III. DISCUSSION: The increased levels of alterations in the microsatellites, particularly in D6S251, and the random amplified polymorphic DNA fingerprints were statistically significant in squamous cell carcinomas, compared with actinic keratoses. CONCLUSION: The overall alterations that were observed in the repetitive DNA of actinic keratoses and

  18. Genomic instability and telomere fusion of canine osteosarcoma cells.

    Directory of Open Access Journals (Sweden)

    Junko Maeda

    Full Text Available Canine osteosarcoma (OSA is known to present with highly variable and chaotic karyotypes, including hypodiploidy, hyperdiploidy, and increased numbers of metacentric chromosomes. The spectrum of genomic instabilities in canine OSA has significantly augmented the difficulty in clearly defining the biological and clinical significance of the observed cytogenetic abnormalities. In this study, eight canine OSA cell lines were used to investigate telomere fusions by fluorescence in situ hybridization (FISH using a peptide nucleotide acid probe. We characterized each cell line by classical cytogenetic studies and cellular phenotypes including telomere associated factors and then evaluated correlations from this data. All eight canine OSA cell lines displayed increased abnormal metacentric chromosomes and exhibited numerous telomere fusions and interstitial telomeric signals. Also, as evidence of unstable telomeres, colocalization of γ-H2AX and telomere signals in interphase cells was observed. Each cell line was characterized by a combination of data representing cellular doubling time, DNA content, chromosome number, metacentric chromosome frequency, telomere signal level, cellular radiosensitivity, and DNA-PKcs protein expression level. We have also studied primary cultures from 10 spontaneous canine OSAs. Based on the observation of telomere aberrations in those primary cell cultures, we are reasonably certain that our observations in cell lines are not an artifact of prolonged culture. A correlation between telomere fusions and the other characteristics analyzed in our study could not be identified. However, it is important to note that all of the canine OSA samples exhibiting telomere fusion utilized in our study were telomerase positive. Pending further research regarding telomerase negative canine OSA cell lines, our findings may suggest telomere fusions can potentially serve as a novel marker for canine OSA.

  19. Induction of genomic instability and activation of autophagy in artificial human aneuploid cells

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    Ariyoshi, Kentaro [Hirosaki University, Institute of Radiation Emergency Medicine, 66-1 Hon-cho, Hirosaki 036-8564 (Japan); Miura, Tomisato; Kasai, Kosuke; Fujishima, Yohei [Department of Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, 66-1 Hon-cho, Hirosaki 036-8564 (Japan); Oshimura, Mitsuo [Chromosome Engineering Research Center (CERC), Tottori University, Nishicho 86, Yonago, Tottori 683-8503 (Japan); Yoshida, Mitsuaki A., E-mail: ariyoshi@hirosaki-u.ac.jp [Hirosaki University, Institute of Radiation Emergency Medicine, 66-1 Hon-cho, Hirosaki 036-8564 (Japan)

    2016-08-15

    Highlights: • Clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. • Increased autophagy was observed in the artificially aneuploid clones. • Inhibition of autophagy resulted in increased genomic instability and DNA damage. • Intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones. - Abstract: Chromosome missegregation can lead to a change in chromosome number known as aneuploidy. Although aneuploidy is a known hallmark of cancer cells, the various mechanisms by which altered gene and/or DNA copy number facilitate tumorigenesis remain unclear. To understand the effect of aneuploidy occurring in non-tumorigenic human breast epithelial cells, we generated clones harboring artificial aneuploidy using microcell-mediated chromosome transfer. Our results demonstrate that clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. Also, the increased autophagy was observed in the artificially aneuploidy clones, and inhibition of autophagy resulted in increased genomic instability and DNA damage. In addition, the intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones, and inhibition of autophagy further increased the production of reactive oxygen species. Together, these results suggest that even a single extraneous chromosome can induce genomic instability, and that autophagy triggered by aneuploidy-induced stress is a mechanism to protect cells bearing abnormal chromosome number.

  20. Induction of genomic instability and activation of autophagy in artificial human aneuploid cells

    International Nuclear Information System (INIS)

    Ariyoshi, Kentaro; Miura, Tomisato; Kasai, Kosuke; Fujishima, Yohei; Oshimura, Mitsuo; Yoshida, Mitsuaki A.

    2016-01-01

    Highlights: • Clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. • Increased autophagy was observed in the artificially aneuploid clones. • Inhibition of autophagy resulted in increased genomic instability and DNA damage. • Intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones. - Abstract: Chromosome missegregation can lead to a change in chromosome number known as aneuploidy. Although aneuploidy is a known hallmark of cancer cells, the various mechanisms by which altered gene and/or DNA copy number facilitate tumorigenesis remain unclear. To understand the effect of aneuploidy occurring in non-tumorigenic human breast epithelial cells, we generated clones harboring artificial aneuploidy using microcell-mediated chromosome transfer. Our results demonstrate that clones with artificial aneuploidy of chromosome 8 or chromosome 22 both show inhibited proliferation and genomic instability. Also, the increased autophagy was observed in the artificially aneuploidy clones, and inhibition of autophagy resulted in increased genomic instability and DNA damage. In addition, the intracellular levels of reactive oxygen species were up-regulated in the artificially aneuploid clones, and inhibition of autophagy further increased the production of reactive oxygen species. Together, these results suggest that even a single extraneous chromosome can induce genomic instability, and that autophagy triggered by aneuploidy-induced stress is a mechanism to protect cells bearing abnormal chromosome number.

  1. Radionuclides in radiation-induced bystander effect; may it share in radionuclide therapy?

    Science.gov (United States)

    Widel, M

    2017-01-01

    For many years in radiobiology and radiotherapy predominated the conviction that cellular DNA is the main target for ionizing radiation, however, the view has changed in the past 20 years. Nowadays, it is assumed that not only directed (targeted) radiation effect, but also an indirect (non-targeted) effect may contribute to the result of radiation treatment. Non-targeted effect is relatively well recognized after external beam irradiation in vitro and in vivo, and comprises such phenomena like radiation-induced bystander effect (RIBE), genomic instability, adaptive response and abscopal (out of field) effect. These stress-induced and molecular signaling mediated phenomena appear in non-targeted cells as variety responses resembling that observed in directly hit cells. Bystander effects can be both detrimental and beneficial in dependence on dose, dose-rate, cell type, genetic status and experimental condition. Less is known about radionuclide-induced non-targeted effects in radionuclide therapy, although, based on characteristics of the radionuclide radiation, on experiments in vitro utilizing classical and 3-D cell cultures, and preclinical study on animals it seems obvious that exposure to radionuclide is accompanied by various bystander effects, mostly damaging, less often protective. This review summarizes existing data on radionuclide induced bystander effects comprising radionuclides emitting beta- and alpha-particles and Auger electrons used in tumor radiotherapy and diagnostics. So far, separation of the direct effect of radionuclide decay from crossfire and bystander effects in clinical targeted radionuclide therapy is impossible because of the lack of methods to assess whether, and to what extent bystander effect is involved in human organism. Considerations on this topic are also included.

  2. Genomic instability: potential contributions to tumour and normal tissue response, and second tumours, after radiotherapy

    International Nuclear Information System (INIS)

    Hendry, Jolyon H.

    2001-01-01

    Purpose: Induced genomic instability generally refers to a type of damage which is transmissible down cell generations, and which results in a persistently enhanced frequency of de novo mutations, chromosomal abnormalities or lethality in a significant fraction of the descendant cell population. The potential contribution of induced genomic instability to tumour and normal tissue response, and second tumours, after radiotherapy, is explored. Results: The phenomenon of spontaneous genomic instability is well known in some rare genetic diseases (e.g. Gorlin's syndrome), and there is evidence in such cases that it can lead to a greater propensity for carcinogenesis (with shortened latency) which is enhanced after irradiation. It is unclear what role induced genomic instability plays in the response of normal individuals, but persistent chromosomal instability has been detected in vivo in lymphocytes and keratinocytes from irradiated normal individuals. Such induced genomic instability might play some role in tumour response in a subset of tumours with specific defects in damage response genes, but again its contribution to radiocurability in the majority of cancer patients is unclear. In normal tissues, genomic instability induced in wild-type cells leading to delayed cell death might contribute to more severe or prolonged early reactions as a consequence of increased cell loss, a longer time required for recovery, and greater residual injury. In tumours, induced genomic instability reflected in delayed reductions in clonogenic capacity might contribute to the radiosensitivity of primary tumours, and also to a lower incidence, longer latency and slower growth rate of recurrences and metastases. Conclusions: The evidence which is reviewed shows that there is little information at present to support these propositions, but what exists is consistent with their expectations. Also, it is not yet clear to what extent mutations associated with genomic instability

  3. Radiation-induced Genomic Instability and Radiation Sensitivity

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    Varnum, Susan M.; Sowa, Marianne B.; Kim, Grace J.; Morgan, William F.

    2013-01-19

    The obvious relationships between reactive oxygen and nitrogen species, mitochondrial dysfunction, inflammatory type responses and reactive chemokines and cytokines suggests a general stress response induced by ionizing radiation most likely leads to the non-targeted effects described after radiation exposure. We argue that true bystander effects do not occur in the radiation therapy clinic. But there is no question that effects outside the target volume do occur. These “out of field effects” are considered very low dose effects in the context of therapy. So what are the implications of non-targeted effects on radiation sensitivity? The primary goal of therapy is to eradicate the tumor. Given the genetic diversity of the human population, lifestyle and environment factors it is likely some combination of these will influence patient outcome. Non-targeted effects may contribute to a greater or lesser extent. But consider the potential situation involving a partial body exposure due to a radiation accident or radiological terrorism. Non-targeted effects suggest that the tissue at risk for demonstrating possible detrimental effects of radiation exposure might be greater than the volume actually irradiated.

  4. Loss of RMI2 Increases Genome Instability and Causes a Bloom-Like Syndrome.

    Directory of Open Access Journals (Sweden)

    Damien F Hudson

    2016-12-01

    Full Text Available Bloom syndrome is a recessive human genetic disorder with features of genome instability, growth deficiency and predisposition to cancer. The only known causative gene is the BLM helicase that is a member of a protein complex along with topoisomerase III alpha, RMI1 and 2, which maintains replication fork stability and dissolves double Holliday junctions to prevent genome instability. Here we report the identification of a second gene, RMI2, that is deleted in affected siblings with Bloom-like features. Cells from homozygous individuals exhibit elevated rates of sister chromatid exchange, anaphase DNA bridges and micronuclei. Similar genome and chromosome instability phenotypes are observed in independently derived RMI2 knockout cells. In both patient and knockout cell lines reduced localisation of BLM to ultra fine DNA bridges and FANCD2 at foci linking bridges are observed. Overall, loss of RMI2 produces a partially active BLM complex with mild features of Bloom syndrome.

  5. Detection of genomic instability in normal human bronchial epithelial cells exposed to 238Pu

    International Nuclear Information System (INIS)

    Kennedy, C.H.; Fukushima, N.H.; Neft, R.E.; Lechner, J.F.

    1994-01-01

    Alpha particle-emitting radon daughters constitute a risk for development of lung cancer in humans. The development of this disease involves multiple genetic alterations. These changes and the time course they follow are not yet defined despite numerous in vitro endeavors to transform human lung cells with various physical or chemical agents. However, genomic instability, characterized both by structural and numerical chromosomal aberrations and by elevated rates of point mutations, is a common feature of tumor cells. Further, both types of genomic instability have been reported in the noncancerous progeny of normal murine hemopoietic cells exposed in vitro to α-particles. The purpose of this investigation was to determine if genomic instability is also a prominent feature of normal human bronchial epithelial cells exposed to α-particle irradiation from the decay of inhaled radon daughters

  6. Radiation-induced genomic instability driven by de novo chromosomal rearrangement hot spots

    International Nuclear Information System (INIS)

    Grosovsky, A.J.; Allen, R.N.; Moore, S.R.

    2003-01-01

    Genomic instability has become generally recognized as a critical contributor to tumor progression by generating the necessary number of genetic alterations required for expression of a clinically significant malignancy. Our study of chromosomal instability investigates the hypothesis that chromosomal rearrangements can generate novel breakage-prone sites, resulting in instability acting predominantly in cis. Here we present an analysis of the karyotypic distribution of instability associated chromosomal rearrangements in TK6 and derivative human lymphoblasts. Karyotypic analysis performed on a total of 455 independent clones included 183 rearrangements distributed among 100 separate unstable clones. The results demonstrate that the breakpoints of chromosomal rearrangements in unstable clones are non-randomly distributed throughout the genome. This pattern is statistically significant, and incompatible with expectations for random breakage associated with loss or alteration of a trans-acting factor. Furthermore, specific chromosomal breakage hot spots associated with instability have been identified; these occur in several independent unstable clones and are often repeatedly broken and rejoined during the outgrowth of an individual clone. In complimentary studies, genomic instability was generated without any exposure to a DNA-damaging agent, but rather by transfection with alpha heterochromatin DNA. In a prospective analysis, human-hamster hybrid AL cells containing a single human chromosome 11 were transfected with heterochromatic alpha DNA repeats and clones were analyzed by chromosome 11 painting. Transfection with alpha DNA was associated with karyotypic heterogeneity in 40% of clones examined; control transfections with plasmid alone did not lead to karyotypic heterogeneity

  7. Molecular Mechanisms Underlying Genomic Instability in Brca-Deficient Cells

    Science.gov (United States)

    2014-11-01

    increased by hydroxyurea, ATR inhibition, deregulated c-Myc expression and by PARPi treatment of BRCA1 deficient cells. This work was recently published...Genome Stability." 6: May 27, 2013-Collaborative Research Center 655 from Cells to Tissues seminar series at the Max-Planck-Institute in Dresden, Germany ...Eisenach, Germany -“Genome Stability during DNA Replication” 8: May 3, 2013- Chemical and Systems Biology Department Seminar Series at Stanford

  8. New type of genome instability in Drosophila melanogaster

    International Nuclear Information System (INIS)

    Georgiev, P.G.; Simonova, O.B.; Gerasimova, T.I.

    1988-01-01

    During crossing of two stable laboratory lines, y 2 sc 1w aG and Df(1)Pgd-kz/FM4, y 31d sc 8 dm B, consistent instability originated reproducibly in progeny containing a y 2 sc 1 w aG chromosome and autosomes of both lines. It is expressed in active mutagenesis observed over the course of several tens of generations. Destabilization occurs independently of direction of crossing. Mutagenesis occurs both in somatic and in sex cells of males and females. It displays high locus specificity. A transpositional nature was shown for at least some of the mutations. Results of the experiments concerning hybridization in situ with different mobile elements indicates an absence or low frequency of tranpositional bursts in the system. Possible mechanisms of induction of genetic instability in the system described are discussed

  9. Study on the relationship between DNA-PKcs and genomic instability and hyper-radiosensitivity

    International Nuclear Information System (INIS)

    Yang Kang; Zhu Jiayun; Ding Nan; Li Junhong; Hu Wentao; Su Fengtao; He Jinpeng; Li Sha

    2010-01-01

    To investigate the relationship between DNA-PKcs and genome instability and hyper-radiosensitivity, human glioma cell lines M059K and M059J, as a model expressing wild-type DNA-PKcs and a model defective in DNA-PKcs activity, were exposed to low doses of X-rays. Cells survival fractions were assessed by colony-forming assay and Cytochalasin-B micronucleus assay was employed to detect the genomic instability happening in each single irradiated colony. It has been found that as the post-incubation time increased, M059K cells expressing wild-type DNA-PKcs exhibited low-dose hyper-radiosensitivity and showed a similar genomic instability after 0.2 Gy and 0.6 Gy irradiations, but the M059J cells lacking in DNA-PKcs didn't present low-dose hyper-radiosensitivity and showed a higher genomic instability of 0.6 Gy than that of 0.2 Gy. The results indicate that DNA-PKcs may act as one of the key factors that lead to low-dose hyper-radiosensitivity. (authors)

  10. Bystander Effects of Ionizing Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Little, John B. [Harvard T.H. Chan School of Public Health, Boston, MA (United States). Dept. of Genetics and Complex Diseases

    2017-01-17

    The objectives of this grant renewal are to provide administrative support and travel funds to allow the continued participation of the principal investigator (Dr. John B. Little) as an advisor to research initiated by several research fellows from his laboratory. The actual research will be carried out under the direction of Dr. Hatsumi Nagasawa with the collaboration of Dr. Joel Bedford at the Colorado State University, and by Drs. Edouard Azzam and Sonia de Toledo at the University of Medicine and Dentistry of New Jersey. Dr. Little will advise on the planning of experiments and development of experimental protocols, the analysis of data, and the preparation of manuscripts for publication. The Specific Aims for several of the planned experiments include: 1) to extend studies of the role of recombinational repair in the bystander effect by examining other genes in this pathway and cell lines deficient in excision repair; 2) to continue studies to determine the nature of the damage signal transmitted to bystander cells including the expression of several connexins in the bystander response, and the extent to which the enhanced oxidative metabolism observed in bystander cells may relate to the nature of the transmitted bystander signal; 3) to utilize a genome-wide approach to examine the genetic basis for the hypersensitivity to ionization we have observed in unaffected parents of patients with hereditary retinoblastoma, as well as from a group of apparently normal individuals that show similar radiosensitivity; 4) to complete studies concerning the induction of high frequencies of cells with massive chromosome damage in clonal derivatives of p53 and p21 knockout mouse cell lines; in particular to examine the role of telomere changes in this phenomenon. Overall, the results of these studies should enhance our understanding of the risk of low-dose exposures to ionizing radiation, including human populations to residential radon as well as occupational exposures.

  11. Bystander Effects of Ionizing Radiation

    International Nuclear Information System (INIS)

    Little, John B.

    2017-01-01

    The objectives of this grant renewal are to provide administrative support and travel funds to allow the continued participation of the principal investigator (Dr. John B. Little) as an advisor to research initiated by several research fellows from his laboratory. The actual research will be carried out under the direction of Dr. Hatsumi Nagasawa with the collaboration of Dr. Joel Bedford at the Colorado State University, and by Drs. Edouard Azzam and Sonia de Toledo at the University of Medicine and Dentistry of New Jersey. Dr. Little will advise on the planning of experiments and development of experimental protocols, the analysis of data, and the preparation of manuscripts for publication. The Specific Aims for several of the planned experiments include: 1) to extend studies of the role of recombinational repair in the bystander effect by examining other genes in this pathway and cell lines deficient in excision repair; 2) to continue studies to determine the nature of the damage signal transmitted to bystander cells including the expression of several connexins in the bystander response, and the extent to which the enhanced oxidative metabolism observed in bystander cells may relate to the nature of the transmitted bystander signal; 3) to utilize a genome-wide approach to examine the genetic basis for the hypersensitivity to ionization we have observed in unaffected parents of patients with hereditary retinoblastoma, as well as from a group of apparently normal individuals that show similar radiosensitivity; 4) to complete studies concerning the induction of high frequencies of cells with massive chromosome damage in clonal derivatives of p53 and p21 knockout mouse cell lines; in particular to examine the role of telomere changes in this phenomenon. Overall, the results of these studies should enhance our understanding of the risk of low-dose exposures to ionizing radiation, including human populations to residential radon as well as occupational exposures.

  12. Characterization of genomic instability in Saccharomyces cerevisiae and engaging teaching strategies described in two curricula

    Science.gov (United States)

    Keller, Alexandra P.

    Cancer arises through an accumulation of mutations in the genome. In cancer cells, mutations are frequently caused by DNA rearrangements, which include chromosomal breakages, deletions, insertions, and translocations. Such events contribute to genomic instability, a known hallmark of cancer. To study cycles of chromosomal instability, we are using baker's yeast as a model organism. In yeast, a ChrVII system was previously developed (Admire et al., 2006), in which a disomic yeast strain was used to identify regions of instability on ChrVII. Using this system, a fragile site on the left arm of ChrVII (Admire et al., 2006) was identified and characterized. This study led to insight into mechanisms involved in chromosomal rearrangements and mutations that arise from them as well as to an understanding of mechanisms involved in genomic instability. To further our understanding of genomic instability, I devised a strategy to study instability on a different chromosome (ChrV) (Figure 3), so that we could determine whether lessons learned from the ChrVII system are applicable to other chromosomes, and/or whether other mechanisms of instability could be identified. A suitable strain was generated and analyzed, and our findings suggest that frequencies of instability on the right arm of ChrV are similar to those found in ChrVII. The results from the work in ChrV described in this paper support the idea that the instability found on ChrVII is not an isolated occurrence. My research was supported by an NSF GK-12 grant. The aim of this grant is to improve science education in middle schools, and as part of my participation in this program, I studied and practiced effective science communication methodologies. In attempts to explain my research to middle school students, I collaborated with others to develop methods for explaining genetics and the most important techniques I used in my research. While developing these methods, I learned more about what motivates people to learn

  13. Adaptive response and genomic instability: allosteric response of genome to negative impact

    International Nuclear Information System (INIS)

    Sasaki, Masao S.

    2010-01-01

    Currently, there is an upsurge concern on the unique response of living cells to low dose ionizing radiation for its inconformity to the existing paradigm of the biological action of radiation and its impact on the current understanding of risk evaluation of health effect of radiation in our workplace and environment. For the allosteric response to have significance, the cells must have an excellent sensing mechanism to discriminate tolerable and intolerable signals. In a series of experiments with mammalian, including human, cells, we demonstrated a novel sensing and signaling mechanism in the low-dose irradiated cells that was mediated by a PKCα-p3BMAPK-PLCδ1 feedback regulatory loop. Upon irradiation, PKCα is immediately activated, which in turn activate p38MAPK. The activation of p38MAPK is feedbacked to the activation of PKCα via PLCδ1, which catalyzes the hydrolysis of PtdInsP2 to generate PKCα-directed second messengers DAG and lnsP3. At low doses, the PKCα and p38MAPK continue to be activated for long time through this feedback loop, but when the cells encounter the high dose (>10 cGy or equivalent), the feedback loop is immediately comes to shutdown by deprivation of PKCα protein, known as down-regulation of PKC signaling. Thus, PKCα plays a key role in the long lasting nature of adaptive response to low doses and a binary switch to the genomic instability by too much signals. Tumor suppressor protein, p53, is a downstream effecter

  14. Gastric cancers of Western European and African patients show different patterns of genomic instability

    Directory of Open Access Journals (Sweden)

    Mulder Chris JJ

    2011-01-01

    Full Text Available Abstract Background Infection with H. pylori is important in the etiology of gastric cancer. Gastric cancer is infrequent in Africa, despite high frequencies of H. pylori infection, referred to as the African enigma. Variation in environmental and host factors influencing gastric cancer risk between different populations have been reported but little is known about the biological differences between gastric cancers from different geographic locations. We aim to study genomic instability patterns of gastric cancers obtained from patients from United Kingdom (UK and South Africa (SA, in an attempt to support the African enigma hypothesis at the biological level. Methods DNA was isolated from 67 gastric adenocarcinomas, 33 UK patients, 9 Caucasian SA patients and 25 native SA patients. Microsatellite instability and chromosomal instability were analyzed by PCR and microarray comparative genomic hybridization, respectively. Data was analyzed by supervised univariate and multivariate analyses as well as unsupervised hierarchical cluster analysis. Results Tumors from Caucasian and native SA patients showed significantly more microsatellite instable tumors (p Conclusions Gastric cancers from SA and UK patients show differences in genetic instability patterns, indicating possible different biological mechanisms in patients from different geographical origin. This is of future clinical relevance for stratification of gastric cancer therapy.

  15. Initiation of genome instability and preneoplastic processes through loss of Fhit expression.

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    Joshua C Saldivar

    Full Text Available Genomic instability drives tumorigenesis, but how it is initiated in sporadic neoplasias is unknown. In early preneoplasias, alterations at chromosome fragile sites arise due to DNA replication stress. A frequent, perhaps earliest, genetic alteration in preneoplasias is deletion within the fragile FRA3B/FHIT locus, leading to loss of Fhit protein expression. Because common chromosome fragile sites are exquisitely sensitive to replication stress, it has been proposed that their clonal alterations in cancer cells are due to stress sensitivity rather than to a selective advantage imparted by loss of expression of fragile gene products. Here, we show in normal, transformed, and cancer-derived cell lines that Fhit-depletion causes replication stress-induced DNA double-strand breaks. Using DNA combing, we observed a defect in replication fork progression in Fhit-deficient cells that stemmed primarily from fork stalling and collapse. The likely mechanism for the role of Fhit in replication fork progression is through regulation of Thymidine kinase 1 expression and thymidine triphosphate pool levels; notably, restoration of nucleotide balance rescued DNA replication defects and suppressed DNA breakage in Fhit-deficient cells. Depletion of Fhit did not activate the DNA damage response nor cause cell cycle arrest, allowing continued cell proliferation and ongoing chromosomal instability. This finding was in accord with in vivo studies, as Fhit knockout mouse tissue showed no evidence of cell cycle arrest or senescence yet exhibited numerous somatic DNA copy number aberrations at replication stress-sensitive loci. Furthermore, cells established from Fhit knockout tissue showed rapid immortalization and selection of DNA deletions and amplifications, including amplification of the Mdm2 gene, suggesting that Fhit loss-induced genome instability facilitates transformation. We propose that loss of Fhit expression in precancerous lesions is the first step in the

  16. An update on the mechanisms and pathophysiological consequences of genomic instability with a focus on ionizing radiation

    Directory of Open Access Journals (Sweden)

    Streffer C

    2015-12-01

    Full Text Available Christian Streffer Institute for Medical Radiobiology, University Clinics Essen, Essen, Germany Abstract: The genome of eukaryotic cells is generally instable. DNA damage occurs by endogenous processes and exogenous toxic agents. The efficient DNA repair pathways conserve the genetic information to a large extent throughout the life. However, exposure to genotoxic agents can increase the genomic instability. This phenomenon develops in a delayed manner after approximately 20 and more cell generations. It is comparatively thoroughly investigated after the exposure to ionizing radiation. The increase of genomic instability has been observed after exposures to ionizing radiation in vitro and in vivo as well as with many different types of radiation. The effect is induced over a wide dose range, and it has been found with cell death, chromosomal damage, cell transformations, mutations, double-strand breaks, malformations, and cancers. No specific chromosomes or genomic sites have been observed for such events. The increased genomic instability can be transmitted to the next generation. Possible mechanisms such as oxidative stress (mitochondria may be involved, reduced DNA repair, changes in telomeres, epigenetic effects are discussed. A second wave of oxidative stress has been observed after radiation exposures with considerably high doses as well as with cytotoxic agents at time periods when an increased genomic instability was seen. However, the increase of genomic instability also happens to much lower radiation doses. Hypoxia induces an increase of genomic instability. This effect is apparently connected with a reduction of DNA repair. Changes of telomeres appear as the most probable mechanisms for the increase of genomic instability. Syndromes have been described with a genetic predisposition for high radiosensitivity. These individuals show an increase of cancer, a deficient DNA repair, a disturbed regulation of the cell cycle, and an

  17. Genomic and epigenetic instability in chordoma: current insights

    Directory of Open Access Journals (Sweden)

    Feng Y

    2014-05-01

    Full Text Available Yong Feng,1,2 Jacson K Shen,1,3 Francis J Hornicek,1,3 Zhenfeng Duan1,3 1Department of Orthopedic Surgery, Massachusetts General Hospital, Boston, MA, USA; 2Department of Orthopedic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of China; 3Sarcoma Biology Laboratory, Center for Sarcoma and Connective Tissue Oncology, Massachusetts General Hospital, Boston, MA, USA Abstract: Chordoma is a malignant bone tumor, which currently can only be defined by histologic and immunohistochemical criteria. There are no prognostic biomarkers to predict the clinical outcome or response to treatment yet. Currently, chordoma pathogenesis is very poorly understood; however, recent large-scale genetic and epigenetic studies have identified some of the underlying mechanisms and pathways that may contribute to the disease. In this review, we summarize the most recent findings in the field of chordoma genomics and epigenomics, from comparative genomic hybridization to evaluate chromosomal alteration, large-scale deoxyribonucleic acid (DNA sequencing to determine the gene mutation, microarray to access messenger ribonucleic acid (RNA and microRNA gene expression, and DNA-methylation profiling. These studies may also hold valuable clinical potential in the management of chordoma. Keywords: chordoma, chromosomal alterations, sequencing, miRNA, DNA methylation

  18. Higher-Density Culture in Human Embryonic Stem Cells Results in DNA Damage and Genome Instability

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    Kurt Jacobs

    2016-03-01

    Full Text Available Human embryonic stem cells (hESC show great promise for clinical and research applications, but their well-known proneness to genomic instability hampers the development to their full potential. Here, we demonstrate that medium acidification linked to culture density is the main cause of DNA damage and genomic alterations in hESC grown on feeder layers, and this even in the short time span of a single passage. In line with this, we show that increasing the frequency of the medium refreshments minimizes the levels of DNA damage and genetic instability. Also, we show that cells cultured on laminin-521 do not present this increase in DNA damage when grown at high density, although the (long-term impact on their genomic stability remains to be elucidated. Our results explain the high levels of genome instability observed over the years by many laboratories worldwide, and show that the development of optimal culture conditions is key to solving this problem.

  19. Epigenetic dysregulation underlies radiation-induced transgenerational genome instability in vivo

    International Nuclear Information System (INIS)

    Koturbash, Igor; Baker, Mike; Loree, Jonathan; Kutanzi, Kristy; Hudson, Darryl; Pogribny, Igor; Sedelnikova, Olga; Bonner, William; Kovalchuk, Olga

    2006-01-01

    Purpose: Although modern cancer radiation therapy has led to increased patient survival rates, the risk of radiation treatment-related complications is becoming a growing problem. Among various complications, radiation also poses a threat to the progeny of exposed parents. It causes transgenerational genome instability that is linked to transgenerational carcinogenesis. Although the occurrence of transgenerational genome instability, which manifests as elevated delayed and nontargeted mutation, has been well documented, the mechanisms by which it arises remain obscure. We hypothesized that epigenetic alterations may play a pivotal role in the molecular etiology of transgenerational genome instability. Methods and Materials: We studied the levels of cytosine DNA methylation in somatic tissues of unexposed offspring upon maternal, paternal, or combined parental exposure. Results: We observed a significant loss of global cytosine DNA methylation in the thymus tissue of the offspring upon combined parental exposure. The loss of DNA methylation was paralleled by a significant decrease in the levels of maintenance (DNMT1) and de novo methyltransferases DNMT3a and 3b and methyl-CpG-binding protein MeCP2. Along with profound changes in DNA methylation, we noted a significant accumulation of DNA strand breaks in thymus, which is a radiation carcinogenesis target organ. Conclusions: The observed changes were indicative of a profound epigenetic dysregulation in the offspring, which in turn could lead to genome destabilization and possibly could serve as precursor for transgenerational carcinogenesis. Future studies are clearly needed to address the cellular and carcinogenic repercussions of those changes

  20. Overexpressed of RAD51 suppresses recombination defects: a possible mechanism to reverse genomic instability

    Energy Technology Data Exchange (ETDEWEB)

    Schild, David; Wiese, Claudia

    2009-10-15

    RAD51, a key protein in the homologous recombinational DNA repair (HRR) pathway, is the major strand-transferase required for mitotic recombination. An important early step in HRR is the formation of single-stranded DNA (ss-DNA) coated by RPA (a ss-DNA binding protein). Displacement of RPA by RAD51 is highly regulated and facilitated by a number of different proteins known as the 'recombination mediators'. To assist these recombination mediators, a second group of proteins also is required and we are defining these proteins here as 'recombination co-mediators'. Defects in either recombination mediators or comediators, including BRCA1 and BRCA2, lead to impaired HRR that can genetically be complemented for (i.e. suppressed) by overexpression of RAD51. Defects in HRR have long been known to contribute to genomic instability leading to tumor development. Since genomic instability also slows cell growth, precancerous cells presumably require genomic restabilization to gain a growth advantage. RAD51 is overexpressed in many tumors, and therefore, we hypothesize that the complementing ability of elevated levels of RAD51 in tumors with initial HRR defects limits genomic instability during carcinogenic progression. Of particular interest, this model may also help explain the high frequency of TP53 mutations in human cancers, since wild-type p53 represses RAD51.

  1. Transposable elements as stress adaptive capacitors induce genomic instability in fungal pathogen Magnaporthe oryzae.

    Directory of Open Access Journals (Sweden)

    Sonia Chadha

    Full Text Available A fundamental problem in fungal pathogenesis is to elucidate the evolutionary forces responsible for genomic rearrangements leading to races with fitter genotypes. Understanding the adaptive evolutionary mechanisms requires identification of genomic components and environmental factors reshaping the genome of fungal pathogens to adapt. Herein, Magnaporthe oryzae, a model fungal plant pathogen is used to demonstrate the impact of environmental cues on transposable elements (TE based genome dynamics. For heat shock and copper stress exposed samples, eight TEs belonging to class I and II family were employed to obtain DNA profiles. Stress induced mutant bands showed a positive correlation with dose/duration of stress and provided evidences of TEs role in stress adaptiveness. Further, we demonstrate that genome dynamics differ for the type/family of TEs upon stress exposition and previous reports of stress induced MAGGY transposition has underestimated the role of TEs in M. oryzae. Here, we identified Pyret, MAGGY, Pot3, MINE, Mg-SINE, Grasshopper and MGLR3 as contributors of high genomic instability in M. oryzae in respective order. Sequencing of mutated bands led to the identification of LTR-retrotransposon sequences within regulatory regions of psuedogenes. DNA transposon Pot3 was identified in the coding regions of chromatin remodelling protein containing tyrosinase copper-binding and PWWP domains. LTR-retrotransposons Pyret and MAGGY are identified as key components responsible for the high genomic instability and perhaps these TEs are utilized by M. oryzae for its acclimatization to adverse environmental conditions. Our results demonstrate how common field stresses change genome dynamics of pathogen and provide perspective to explore the role of TEs in genome adaptability, signalling network and its impact on the virulence of fungal pathogens.

  2. Links between persistent DNA damage, genome instability, and aging

    Energy Technology Data Exchange (ETDEWEB)

    Dynan, William S. [Emory Univ., Atlanta, GA (United States). Dept. of Radiation Oncology

    2016-11-14

    The goal of this study was to examine long-term effects of low-dose radiation exposure. One of the hypotheses was that radiation exposure would accelerate the normal aging process. The study was jointly funded by NASA and examined both low-LET radiation (γ-rays) and high-LET radiation (1000 MeV/nucleon 56Fe ions) at doses of 0.1 Gy and up. The work used the Japanese medaka fish (Oryzias latipes), as a vertebrate model organism that can be maintained in large numbers at low cost for lifetime studies. Like other small laboratory fish, Japanese medaka share many anatomical and histological characteristics with other vertebrates, and a variety of genetic and genomic resources are available. Some work also used the zebrafish (Danio rerio), another widely used laboratory model organism.

  3. Dynamic instability of genomic methylation patterns in pluripotent stem cells

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    Ooi Steen KT

    2010-09-01

    Full Text Available Abstract Background Genomic methylation patterns are established during gametogenesis, and perpetuated in somatic cells by faithful maintenance methylation. There have been previous indications that genomic methylation patterns may be less stable in embryonic stem (ES cells than in differentiated somatic cells, but it is not known whether different mechanisms of de novo and maintenance methylation operate in pluripotent stem cells compared with differentiating somatic cells. Results In this paper, we show that ablation of the DNA methyltransferase regulator DNMT3L (DNA methyltransferase 3-like in mouse ES cells renders them essentially incapable of de novo methylation of newly integrated retroviral DNA. We also show that ES cells lacking DNMT3L lose DNA methylation over time in culture, suggesting that DNA methylation in ES cells is the result of dynamic loss and gain of DNA methylation. We found that wild-type female ES cells lose DNA methylation at a much faster rate than do male ES cells; this defect could not be attributed to sex-specific differences in expression of DNMT3L or of any DNA methyltransferase. We also found that human ES and induced pluripotent stem cell lines showed marked but variable loss of methylation that could not be attributed to sex chromosome constitution or time in culture. Conclusions These data indicate that DNA methylation in pluripotent stem cells is much more dynamic and error-prone than is maintenance methylation in differentiated cells. DNA methylation requires DNMT3L in stem cells, but DNMT3L is not expressed in differentiating somatic cells. Error-prone maintenance methylation will introduce unpredictable phenotypic variation into clonal populations of pluripotent stem cells, and this variation is likely to be much more pronounced in cultured female cells. This epigenetic variability has obvious negative implications for the clinical applications of stem cells.

  4. Genomic instability induced by 60Co γ ray radiation in normal human liver cells

    International Nuclear Information System (INIS)

    Gen Xiaohua; Guo Xianhua; Zuo Yahui; Wang Xiaoli; Wang Zhongwen

    2007-01-01

    Objective: To explore the genomic instability induced by 60 Co γ rays. Methods: The cloning efficiency and micronucleus efficiency of normal human liver cell irradiated by 60 Co γ rays were detected, and the method of single cell gel electrophoresis (SCGE) was carried out to measure DNA chains damage. The fast-growing cells were divided into different dose-groups and then irradiated by 60 Co γ rays. After 40 populations doubling, the progenies were secondly irradiated with 2 Gy 60 Co γ rays. Results: The cloning efficiency decreased with the increase of doses after the initial irradiation. After the survival cells were given second irradiation, both results of SCGE and micronucleus frequency showed that the second damage was correlated with the original irradiation doses. Conclusions: 60 Co γ rays can not only induce the immediate biological effects in liver cells, but also lead to the genomic instability in the descendants that leads to an enhanced frequency of genetic changes occurring among the progeny of the original irradiated cell. The expanding effect of second event helps to study the genomic instability. (authors)

  5. Pomegranate Intake Protects Against Genomic Instability Induced by Medical X-rays In Vivo in Mice.

    Science.gov (United States)

    Nallanthighal, Sameera; Shirode, Amit B; Judd, Julius A; Reliene, Ramune

    2016-01-01

    Ionizing radiation (IR) is a well-documented human carcinogen. The increased use of IR in medical procedures has doubled the annual radiation dose and may increase cancer risk. Genomic instability is an intermediate lesion in IR-induced cancer. We examined whether pomegranate extract (PE) suppresses genomic instability induced by x-rays. Mice were treated orally with PE and exposed to an x-ray dose of 2 Gy. PE intake suppressed x-ray-induced DNA double-strand breaks (DSBs) in peripheral blood and chromosomal damage in bone marrow. We hypothesized that PE-mediated protection against x-ray-induced damage may be due to the upregulation of DSB repair and antioxidant enzymes and/or increase in glutathione (GSH) levels. We found that expression of DSB repair genes was not altered (Nbs1 and Rad50) or was reduced (Mre11, DNA-PKcs, Ku80, Rad51, Rad52 and Brca2) in the liver of PE-treated mice. Likewise, mRNA levels of antioxidant enzymes were reduced (Gpx1, Cat, and Sod2) or were not altered (HO-1 and Sod1) as a function of PE treatment. In contrast, PE-treated mice with and without IR exposure displayed higher hepatic GSH concentrations than controls. Thus, ingestion of pomegranate polyphenols is associated with inhibition of x-ray-induced genomic instability and elevated GSH, which may reduce cancer risk.

  6. Reciprocal Regulation between DNA-PKcs and Snail1 Conferring Genomic Instability

    International Nuclear Information System (INIS)

    Seo, Haeng Ran; Lee, Hae June; Jin, Yeung Bae; Bae, Sang Woo; Lee, Yun Sil; Kim, Nam Hee; Kim, Hyun Sil; Nam, Hyung Wook; Yook, Jong In

    2010-01-01

    Although the roles of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) involving non-homologous end joining (NHEJ) of DNA repair are well recognized, the biological mechanisms and regulators by which DNA-PKcs regulate genomic instability are not clearly defined. We show herein that DNA-PKcs activity resulting from DNA damage caused by ionizing radiation (IR) phosphorylates Snail1 at serine 100, which results in increased Snail1 expression and its function by inhibition of GSK-3-mediated phosphorylation. Furthermore, Snail1 phosphorylated at serine 100 can reciprocally inhibit kinase activity of DNA-PKcs, resulting in an inhibition to recruit DNA-PKcs or Ku70/80 to a DNA double-strand break site, and ultimately inhibition of DNA repair activity. The impairment of repair activity by a direct interaction between Snail1 and DNA-PKcs increases the resistance to DNA damaging agents, such as IR, and genomic instability. Our findings provide a novel cellular mechanism for induction of genomic instability by reciprocal regulation of DNA-PKcs and Snail1

  7. Amplification of HER2 is a marker for global genomic instability

    Directory of Open Access Journals (Sweden)

    Love Brad

    2008-10-01

    Full Text Available Abstract Background Genomic alterations of the proto-oncogene c-erbB-2 (HER-2/neu are associated with aggressive behavior and poor prognosis in patients with breast cancer. The variable clinical outcomes seen in patients with similar HER2 status, given similar treatments, suggests that the effects of amplification of HER2 can be influenced by other genetic changes. To assess the broader genomic implications of structural changes at the HER2 locus, we investigated relationships between genomic instability and HER2 status in patients with invasive breast cancer. Methods HER2 status was determined using the PathVysion® assay. DNA was extracted after laser microdissection from the 181 paraffin-embedded HER2 amplified (n = 39 or HER2 negative (n = 142 tumor specimens with sufficient tumor available to perform molecular analysis. Allelic imbalance (AI was assessed using a panel of microsatellite markers representing 26 chromosomal regions commonly altered in breast cancer. Student t-tests and partial correlations were used to investigate relationships between genomic instability and HER2 status. Results The frequency of AI was significantly higher (P P Conclusion The poor prognosis associated with HER2 amplification may be attributed to global genomic instability as cells with high frequencies of chromosomal alterations have been associated with increased cellular proliferation and aggressive behavior. In addition, high levels of DNA damage may render tumor cells refractory to treatment. In addition, specific alterations at chromosomes 11q13, 16q22-q24, and 18q21, all of which have been associated with aggressive tumor behavior, may serve as genetic modifiers to HER2 amplification. These data not only improve our understanding of HER in breast pathogenesis but may allow more accurate risk profiles and better treatment options to be developed.

  8. Upregulation of FOXM1 induces genomic instability in human epidermal keratinocytes

    Directory of Open Access Journals (Sweden)

    Philpott Michael P

    2010-02-01

    Full Text Available Abstract Background The human cell cycle transcription factor FOXM1 is known to play a key role in regulating timely mitotic progression and accurate chromosomal segregation during cell division. Deregulation of FOXM1 has been linked to a majority of human cancers. We previously showed that FOXM1 was upregulated in basal cell carcinoma and recently reported that upregulation of FOXM1 precedes malignancy in a number of solid human cancer types including oral, oesophagus, lung, breast, kidney, bladder and uterus. This indicates that upregulation of FOXM1 may be an early molecular signal required for aberrant cell cycle and cancer initiation. Results The present study investigated the putative early mechanism of UVB and FOXM1 in skin cancer initiation. We have demonstrated that UVB dose-dependently increased FOXM1 protein levels through protein stabilisation and accumulation rather than de novo mRNA expression in human epidermal keratinocytes. FOXM1 upregulation in primary human keratinocytes triggered pro-apoptotic/DNA-damage checkpoint response genes such as p21, p38 MAPK, p53 and PARP, however, without causing significant cell cycle arrest or cell death. Using a high-resolution Affymetrix genome-wide single nucleotide polymorphism (SNP mapping technique, we provided the evidence that FOXM1 upregulation in epidermal keratinocytes is sufficient to induce genomic instability, in the form of loss of heterozygosity (LOH and copy number variations (CNV. FOXM1-induced genomic instability was significantly enhanced and accumulated with increasing cell passage and this instability was increased even further upon exposure to UVB resulting in whole chromosomal gain (7p21.3-7q36.3 and segmental LOH (6q25.1-6q25.3. Conclusion We hypothesise that prolonged and repeated UVB exposure selects for skin cells bearing stable FOXM1 protein causes aberrant cell cycle checkpoint thereby allowing ectopic cell cycle entry and subsequent genomic instability. The aberrant

  9. Bystander effects of radiation

    International Nuclear Information System (INIS)

    Umar, Neethu Fathima; Daniel, Nittu

    2013-01-01

    The Radiation-Induced Bystander Effect is the phenomenon in which unirradiated cells show irradiated effects due to the signals received from nearby irradiated cells. Evidence suggests that targeted cytoplasmic irradiation results in mutation in the nucleus of the hit cells. Cells that are not directly hit by an alpha particle, but are in the vicinity of one that is hit, also contribute to the genotoxic response of the cell population. When cells are irradiated, and the medium is transferred to unirradiated cells, these unirradiated cells show bystander responses when assayed for clonogenic survival and oncogenic transformation. The demonstration of a bystander effect in human tissues and, more recently, in whole organisms have clear implication of the potential relevance of the non-targeted response to human health. This effect may also contribute to the final biological consequences of exposure to low doses of radiation. The radiation-induced bystander effect represents a paradigm shift in our understanding of the radiobiological effects of ionizing radiation, in that extranuclear and extracellular events may also contribute to the final biological consequences of exposure to low doses of radiation. Multiple pathways are involved in the bystander phenomenon, and different cell types respond differently to bystander signalling. Using cDNA microarrays, a number of cellular signalling genes, including cyclooxygenase-2 (CQX-2), have been shown to be casually linked to the bystander phenomenon. The observation that inhibition of the phosphorylation of extracellular signal-related kinase (ERK) suppressed the bystander response further confirmed the important role of the mitogen-activated protein kinase (MAPK) signalling cascade in the bystander process. The cells deficient in mitochondrial DNA showed a significantly reduced response to bystander signalling, suggesting a functional role of mitochondria in the signalling process. (author)

  10. Nitric oxide coordinates development of genomic instability in realization of combined effect with ionizing radiation.

    Science.gov (United States)

    Mikhailenko, V M; Diomina, E A; Muzalov, I I; Gerashchenko, B I

    2013-03-01

    The aim of this study was to investigate the ability of environmental nitrogen oxides or natural nitric oxide (NO) donors to modify free radicals ba-lance and development of genomic instability alone or in combination with ionizing radiation. Genotoxicity and cytogenetic abnormalities were assessed in vitro in peripheral blood lymphocytes (PBL) isolated from healthy humans or in vivo in rats PBL. Human PBL were treated with physiologically relevant NO donor - S-Nitrosoglutathione and X-ray irradiation. The inhalation treatment of animals with NO was carried out in chamber with purified gaseous NO mixed inside with air. Levels of S-Nitrosohemoglobin and methemoglobin in the blood were assessed with electron paramagnetic resonance. The total level of reactive oxygen and nitrogen species in PBL was determined fluorometrically, and serum levels of reactive oxygen species was determined by spectrophotometric assay. DNA damages were assessed by alkaline single-cell gel electrophoresis. The frequency of chromosomal aberrations in human PBL measured with the conventional cytogenetic assay in metaphase cells on short-term (52 h) and long-term (72 h) cultures. Environmental nitrogen oxides or release of NO from stable complexes with biomolecules (such as S-Nitrosothiols) intensified generation of free radicals, DNA damage and development of genomic instability alone or in combination with ionizing radiation. Treatment of PBL by S-Nitrosoglutathione caused prevalent induction of chromatid type but irradiation - chromosome aberrations. The dose dependence of chromatid-type aberrations observed in human PBL after combined influence of S-Nitrosoglutathione and ionizing radiation indicates a crucial role of NO in the formation of chromosomal instability. NO can deregulate free radicals balance resulted in genotoxic effect, posttranslational modification of repair enzymes and thus coordinated development of genomic instability and increase of cancer risk.

  11. The elevation of radiation load on ecosystems and genome instability of organisms

    International Nuclear Information System (INIS)

    Gaziyev, A. I.; Bezlepkin, V.Q.

    2002-01-01

    prophylaxis of human disorders. Thus, it was found that the action of low-dose ionizing radiation on living organisms might induce an adaptive repair response in them aimed at decreasing the genetic consequences of the exposure. However, the potentialities of defense and repair systems of an organism are limited, so an increase in genome lesions may cause inheritable mutations, cancer and other pathologies, and death. DNA lesions caused by ionizing radiation in small and sublethal doses can essentially be repaired, whereas unrepaired lesions and errors of repair, replication, and recombination systems lead to formation of mutational changes in DNA sequences. These changes may be transmitted to daughter cells and induce genome instability in the progeny. Induced genome instability in survived somatic cells is characterized by persistence of a high level of acquired variability in many generations of these cells. Genome instability manifests itself as an increased frequency of karyotypic anomalies, chromosome and gene mutations, clonal heterogeneity, and malignant transformation in the progeny of cells exposed to DNA-damaging agents. Besides, cells with genome instability show increased amplification of genes and changes in their expression, as well as disturbances in their differentiation, delays in reproductive death and other phenotypic characters of abnormal development. Whereas some progress has been made towards knowledge of genome instability in the somatic cells of mammals, the radiation-induced genome instability in germ cells transmitted to individuals of the next generation is still not clearly understood. At the same time, evidence has been obtained which suggests that the transmission of genome instability to the somatic cells of the progeny from the germ cells of gamma - radiation-exposed parents is possible. This conclusion is based on the data on mutation frequency in the progeny of parents exposed to DNA-damaging agents. For instance, a significant increase in

  12. PTEN C-Terminal Deletion Causes Genomic Instability and Tumor Development

    Directory of Open Access Journals (Sweden)

    Zhuo Sun

    2014-03-01

    Full Text Available Tumor suppressor PTEN controls genomic stability and inhibits tumorigenesis. The N-terminal phosphatase domain of PTEN antagonizes the PI3K/AKT pathway, but its C-terminal function is less defined. Here, we describe a knockin mouse model of a nonsense mutation that results in the deletion of the entire Pten C-terminal region, referred to as PtenΔC. Mice heterozygous for PtenΔC develop multiple spontaneous tumors, including cancers and B cell lymphoma. Heterozygous deletion of the Pten C-terminal domain also causes genomic instability and common fragile site rearrangement. We found that Pten C-terminal disruption induces p53 and its downstream targets. Simultaneous depletion of p53 promotes metastasis without influencing the initiation of tumors, suggesting that p53 mainly suppresses tumor progression. Our data highlight the essential role of the PTEN C terminus in the maintenance of genomic stability and suppression of tumorigenesis.

  13. Human RTEL1 deficiency causes Hoyeraal-Hreidarsson syndrome with short telomeres and genome instability.

    Science.gov (United States)

    Le Guen, Tangui; Jullien, Laurent; Touzot, Fabien; Schertzer, Michael; Gaillard, Laetitia; Perderiset, Mylène; Carpentier, Wassila; Nitschke, Patrick; Picard, Capucine; Couillault, Gérard; Soulier, Jean; Fischer, Alain; Callebaut, Isabelle; Jabado, Nada; Londono-Vallejo, Arturo; de Villartay, Jean-Pierre; Revy, Patrick

    2013-08-15

    Hoyeraal-Hreidarsson syndrome (HHS), a severe variant of dyskeratosis congenita (DC), is characterized by early onset bone marrow failure, immunodeficiency and developmental defects. Several factors involved in telomere length maintenance and/or protection are defective in HHS/DC, underlining the relationship between telomere dysfunction and these diseases. By combining whole-genome linkage analysis and exome sequencing, we identified compound heterozygous RTEL1 (regulator of telomere elongation helicase 1) mutations in three patients with HHS from two unrelated families. RTEL1 is a DNA helicase that participates in DNA replication, DNA repair and telomere integrity. We show that, in addition to short telomeres, RTEL1-deficient cells from patients exhibit hallmarks of genome instability, including spontaneous DNA damage, anaphase bridges and telomeric aberrations. Collectively, these results identify RTEL1 as a novel HHS-causing gene and highlight its role as a genomic caretaker in humans.

  14. Aberrant methylation and associated transcriptional mobilization of Alu elements contributes to genomic instability in hypoxia.

    Science.gov (United States)

    Pal, Arnab; Srivastava, Tapasya; Sharma, Manish K; Mehndiratta, Mohit; Das, Prerna; Sinha, Subrata; Chattopadhyay, Parthaprasad

    2010-11-01

    Hypoxia is an integral part of tumorigenesis and contributes extensively to the neoplastic phenotype including drug resistance and genomic instability. It has also been reported that hypoxia results in global demethylation. Because a majority of the cytosine-phosphate-guanine (CpG) islands are found within the repeat elements of DNA, and are usually methylated under normoxic conditions, we suggested that retrotransposable Alu or short interspersed nuclear elements (SINEs) which show altered methylation and associated changes of gene expression during hypoxia, could be associated with genomic instability. U87MG glioblastoma cells were cultured in 0.1% O₂ for 6 weeks and compared with cells cultured in 21% O₂ for the same duration. Real-time PCR analysis showed a significant increase in SINE and reverse transcriptase coding long interspersed nuclear element (LINE) transcripts during hypoxia. Sequencing of bisulphite treated DNA as well as the Combined Bisulfite Restriction Analysis (COBRA) assay showed that the SINE loci studied underwent significant hypomethylation though there was patchy hypermethylation at a few sites. The inter-alu PCR profile of DNA from cells cultured under 6-week hypoxia, its 4-week revert back to normoxia and 6-week normoxia showed several changes in the band pattern indicating increased alu mediated genomic alteration. Our results show that aberrant methylation leading to increased transcription of SINE and reverse transcriptase associated LINE elements could lead to increased genomic instability in hypoxia. This might be a cause of genetic heterogeneity in tumours especially in variegated hypoxic environment and lead to a development of foci of more aggressive tumour cells. © 2009 The Authors Journal compilation © 2010 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

  15. Early telomere shortening and genomic instability in tubo-ovarian preneoplastic lesions.

    Science.gov (United States)

    Chene, Gautier; Tchirkov, Andrei; Pierre-Eymard, Eleonore; Dauplat, Jacques; Raoelfils, Ines; Cayre, Anne; Watkin, Emmanuel; Vago, Philippe; Penault-Llorca, Frederique

    2013-06-01

    Genetic instability plays an important role in ovarian carcinogenesis. We investigated the level of telomere shortening and genomic instability in early and preinvasive stages of ovarian cancer, serous tubal intraepithelial carcinoma (STIC), and tubo-ovarian dysplasia (TOD). Fifty-one TOD from prophylactic salpingo-oophorectomies with BRCA1 or 2 mutation, 12 STICs, 53 tubo-ovarian high-grade serous carcinoma, and 36 noncancerous controls were laser capture microdissected from formalin-fixed, paraffin-embedded sections, analyzed by comparative genomic hybridization (array CGH) and for telomere length (using quantitative real-time PCR based on the Cawthon's method). TOD and STICs were defined by morphologic scores and immunohistochemical expressions of p53, Ki67, and γH2AX. TOD showed marked telomere shortening compared with noncancerous controls (P STICs had even shorter telomeres than TOD (P = 0.0008). Ovarian carcinoma had shorter telomeres than controls but longer than STICs and dysplasia. In TOD, telomeres were significantly shorter in those with BRCA1 mutation than in those with BRCA2 mutation (P = 0.005). In addition, γH2AX expression in TOD and STIC groups with short telomeres was significantly increased (P STICs. The total number of genetic alterations was the highest in ovarian cancers. These findings suggest that genetic instability occurs in early stages of ovarian tumorigenesis. STICs and noninvasive dysplasia are likely an important step in early serous ovarian neoplasia. ©2013 AACR

  16. Radiation-induced hyperproliferation of intestinal crypts results in elevated genome instability with inactive p53-related genomic surveillance.

    Science.gov (United States)

    Zhou, Xin; Ma, Xiaofei; Wang, Zhenhua; Sun, Chao; Wang, Yupei; He, Yang; Zhang, Hong

    2015-12-15

    Radiation-induced hyperproliferation of intestinal crypts is well documented, but its potential tumorigenic effects remain elusive. Here we aim to determine the genomic surveillance process during crypt hyperproliferation, and its consequential outcome after ionizing radiation. Crypt regeneration in the intestine was induced by a single dose of 12Gy abdominal irradiation. γ-H2AX, 53BP1 and DNA-PKcs were used as DNA repair surrogates to investigate the inherent ability of intestinal crypt cells to recognize and repair double-strand breaks. Ki67 staining and the 5-bromo-2'-deoxyuridine incorporation assay were used to study patterns of cell proliferation in regenerating crypts. Staining for ATM, p53, Chk1 and Chk2 was performed to study checkpoint activation and release. Apoptosis was evaluated through H&E staining and terminal deoxynucleotidyl transferase (dUTP) nick-end labeling. The ATM-p53 pathway was immediately activated after irradiation. A second wave of DSBs in crypt cells was observed in regenerating crypts, accompanied with significantly increased chromosomal bridges. The p53-related genomic surveillance pathway was not active during the regeneration phase despite DSBs and chromosomal bridges in the cells of regenerating crypts. Non-homologous end joining (NHEJ) DSBs repair was involved in the DSBs repair process, as indicated by p-DNA-PKcs staining. Intestinal crypt cells retained hyperproliferation with inactive p53-related genomic surveillance system. NHEJ was involved in the resultant genomic instability during hyperproliferation. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Genomic instability in rat: Breakpoints induced by ionising radiation and interstitial telomeric-like sequences

    International Nuclear Information System (INIS)

    Camats, Nuria; Ruiz-Herrera, Aurora; Parrilla, Juan Jose; Acien, Maribel; Paya, Pilar; Giulotto, Elena; Egozcue, Josep; Garcia, Francisca; Garcia, Montserrat

    2006-01-01

    The Norwegian rat (Rattus norvegicus) is the most widely studied experimental species in biomedical research although little is known about its chromosomal structure. The characterisation of possible unstable regions of the karyotype of this species would contribute to the better understanding of its genomic architecture. The cytogenetic effects of ionising radiation have been widely used for the study of genomic instability, and the importance of interstitial telomeric-like sequences (ITSs) in instability of the genome has also been reported in previous studies in vertebrates. In order to describe the unstable chromosomal regions of R. norvegicus, the distribution of breakpoints induced by X-irradiation and ITSs in its karyotype were analysed in this work. For the X-irradiation analysis, 52 foetuses (from 14 irradiated rats) were studied, 4803 metaphases were analysed, and a total of 456 breakpoints induced by X-rays were detected, located in 114 chromosomal bands, with 25 of them significantly affected by X-irradiation (hot spots). For the analysis of ITSs, three foetuses (from three rats) were studied, 305 metaphases were analysed and 121 ITSs were detected, widely distributed in the karyotype of this species. Seventy-six percent of all hot spots analysed in this study were co-localised with ITSs

  18. Genomic instability in rat: Breakpoints induced by ionising radiation and interstitial telomeric-like sequences

    Energy Technology Data Exchange (ETDEWEB)

    Camats, Nuria [Institut de Biotecnologia i Biomedicina (IBB), Universitat Autonoma de Barcelona, 08193 Barcelona (Spain); Departament de Biologia Cel.lular, Fisiologia i Immunologia Universitat Autonoma de Barcelona, 08193 Barcelona (Spain); Ruiz-Herrera, Aurora [Departament de Biologia Cel.lular, Fisiologia i Immunologia Universitat Autonoma de Barcelona, 08193 Barcelona (Spain); Parrilla, Juan Jose [Servicio de Ginecologia y Obstetricia, Hospital Universitario Virgen de la Arrixaca, Ctra, Madrid-Cartagena, s/n, El Palmar, 30120 Murcia (Spain); Acien, Maribel [Servicio de Ginecologia y Obstetricia, Hospital Universitario Virgen de la Arrixaca, Ctra, Madrid-Cartagena, s/n, El Palmar, 30120 Murcia (Spain); Paya, Pilar [Servicio de Ginecologia y Obstetricia, Hospital Universitario Virgen de la Arrixaca, Ctra, Madrid-Cartagena, s/n, El Palmar, 30120 Murcia (Spain); Giulotto, Elena [Dipartimento di Genetica e Microbiologia Adriano Buzzati Traverso, Universita degli Studi di Pavia, 27100 Pavia (Italy); Egozcue, Josep [Departament de Biologia Cel.lular, Fisiologia i Immunologia Universitat Autonoma de Barcelona, 08193 Barcelona (Spain); Garcia, Francisca [Institut de Biotecnologia i Biomedicina (IBB), Universitat Autonoma de Barcelona, 08193 Barcelona (Spain); Garcia, Montserrat [Institut de Biotecnologia i Biomedicina (IBB), Universitat Autonoma de Barcelona, 08193 Barcelona (Spain) and Departament de Biologia Cellular, Fisiologia i Immunologia Universitat Autonoma de Barcelona, 08193 Barcelona (Spain)]. E-mail: Montserrat.Garcia.Caldes@uab.es

    2006-03-20

    The Norwegian rat (Rattus norvegicus) is the most widely studied experimental species in biomedical research although little is known about its chromosomal structure. The characterisation of possible unstable regions of the karyotype of this species would contribute to the better understanding of its genomic architecture. The cytogenetic effects of ionising radiation have been widely used for the study of genomic instability, and the importance of interstitial telomeric-like sequences (ITSs) in instability of the genome has also been reported in previous studies in vertebrates. In order to describe the unstable chromosomal regions of R. norvegicus, the distribution of breakpoints induced by X-irradiation and ITSs in its karyotype were analysed in this work. For the X-irradiation analysis, 52 foetuses (from 14 irradiated rats) were studied, 4803 metaphases were analysed, and a total of 456 breakpoints induced by X-rays were detected, located in 114 chromosomal bands, with 25 of them significantly affected by X-irradiation (hot spots). For the analysis of ITSs, three foetuses (from three rats) were studied, 305 metaphases were analysed and 121 ITSs were detected, widely distributed in the karyotype of this species. Seventy-six percent of all hot spots analysed in this study were co-localised with ITSs.

  19. Mitochondrial mutagenesis induced by tumor-specific radiation bystander effects.

    LENUS (Irish Health Repository)

    Gorman, Sheeona

    2012-02-01

    The radiation bystander effect is a cellular process whereby cells not directly exposed to radiation display cellular alterations similar to directly irradiated cells. Cellular targets including mitochondria have been postulated to play a significant role in this process. In this study, we utilized the Random Mutation Capture assay to quantify the levels of random mutations and deletions in the mitochondrial genome of bystander cells. A significant increase in the frequency of random mitochondrial mutations was found at 24 h in bystander cells exposed to conditioned media from irradiated tumor explants (p = 0.018). CG:TA mutations were the most abundant lesion induced. A transient increase in the frequency of random mitochondrial deletions was also detected in bystander cells exposed to conditioned media from tumor but not normal tissue at 24 h (p = 0.028). The increase in both point mutations and deletions was transient and not detected at 72 h. To further investigate mitochondrial dysfunction, mitochondrial membrane potential and reactive oxygen species were assessed in these bystander cells. There was a significant reduction in mitochondrial membrane potential and this was positively associated with the frequency of random point mutation and deletions in bystander cells treated with conditioned media from tumor tissue (r = 0.71, p = 0.02). This study has shown that mitochondrial genome alterations are an acute consequence of the radiation bystander effect secondary to mitochondrial dysfunction and suggests that this cannot be solely attributable to changes in ROS levels alone.

  20. From NGS assembly challenges to instability of fungal mitochondrial genomes: A case study in genome complexity.

    Science.gov (United States)

    Misas, Elizabeth; Muñoz, José Fernando; Gallo, Juan Esteban; McEwen, Juan Guillermo; Clay, Oliver Keatinge

    2016-04-01

    The presence of repetitive or non-unique DNA persisting over sizable regions of a eukaryotic genome can hinder the genome's successful de novo assembly from short reads: ambiguities in assigning genome locations to the non-unique subsequences can result in premature termination of contigs and thus overfragmented assemblies. Fungal mitochondrial (mtDNA) genomes are compact (typically less than 100 kb), yet often contain short non-unique sequences that can be shown to impede their successful de novo assembly in silico. Such repeats can also confuse processes in the cell in vivo. A well-studied example is ectopic (out-of-register, illegitimate) recombination associated with repeat pairs, which can lead to deletion of functionally important genes that are located between the repeats. Repeats that remain conserved over micro- or macroevolutionary timescales despite such risks may indicate functionally or structurally (e.g., for replication) important regions. This principle could form the basis of a mining strategy for accelerating discovery of function in genome sequences. We present here our screening of a sample of 11 fully sequenced fungal mitochondrial genomes by observing where exact k-mer repeats occurred several times; initial analyses motivated us to focus on 17-mers occurring more than three times. Based on the diverse repeats we observe, we propose that such screening may serve as an efficient expedient for gaining a rapid but representative first insight into the repeat landscapes of sparsely characterized mitochondrial chromosomes. Our matching of the flagged repeats to previously reported regions of interest supports the idea that systems of persisting, non-trivial repeats in genomes can often highlight features meriting further attention. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Radiation-induced genomic instability, and the cloning and functional analysis of its related gene

    International Nuclear Information System (INIS)

    Muto, Masahiro; Kanari, Yasuyoshi; Kubo, Eiko; Yamada, Yutaka

    2000-01-01

    Exposure to ionizing radiation produces a number of biological consequences including gene mutations, chromosome aberrations, cellular transformation and cell death. The classical view has been that mutations occur at the sites of DNA damage, that is, damage produced by radiation is converted into a mutation during subsequent DNA replication or as a consequence of enzymatic repair processes. However, many investigators have presented evidence for an alternative mechanism to explain these biological effects. This evidence suggests that radiation may induce a process of genomic instability that is transmissible over many generations of cell replication and that serves to enhance the probability of the occurrence of such genetic effects among the progeny of the irradiated cell after many generations of cell replication. If such a process exists in vivo, it could have significant implications for mechanisms of carcinogenesis. Exposure of B10 mice to fractionated X-irradiation induces a high incidence of thymic lymphomas, whereas the incidence in STS/A mice is very low. Such strain differences are presumably determined genetically, and various genetic factors have been reported to be involved in radiation-induced lymphomagenesis. The mechanism of radiation-induced lymphomagenesis appears to develop through a complex and multistep process. Using this experimental system, we characterized the prelymphoma cells induced by radiation, and identified the genetic changes preceding the development of thymic lymphomas by comparing the oncogenic alterations with the pattern of T cell receptor (TCR) γ rearrangements. In these studies, the latent expression of some chromosomal aberrations and p53 mutations in irradiated progeny has been interpreted to be a manifestation of genomic instability. In the present report we review the results of in vivo studies conducted in our laboratory that support the hypothesis of genomic instability induced by radiation, and we describe the

  2. Transgenerational genomic instability in children of irradiated parents as a result of the Chernobyl Nuclear Accident

    International Nuclear Information System (INIS)

    Aghajanyan, Anna; Suskov, Igor

    2009-01-01

    The study of families irradiated as a result of the accident at the Chernobyl Nuclear Power Plant revealed significantly increased aberrant genomes frequencies (AGFs) not only in irradiated parents (n = 106, p 137 Cs) of peripheral blood samples from the children and their parents at doses of 0.1, 0.2 and 0.3 Gy. The spectrum and frequency of chromosome aberrations were studied in the 1st and 2nd cell generations. The average AGF was significantly increased at all doses (except 0.1 Gy) in children of irradiated parents, as compared to children born from non-irradiated parents. Amplification of cells with single-break chromosome aberrations in mitosis 2, as compared to mitosis 1, suggests the replication mechanism of realization of potential damage in DNA and the occurrence of genomic instability in succeeding cell generations.

  3. Amplification of HER2 is a marker for global genomic instability

    International Nuclear Information System (INIS)

    Ellsworth, Rachel E; Ellsworth, Darrell L; Patney, Heather L; Deyarmin, Brenda; Love, Brad; Hooke, Jeffrey A; Shriver, Craig D

    2008-01-01

    Genomic alterations of the proto-oncogene c-erbB-2 (HER-2/neu) are associated with aggressive behavior and poor prognosis in patients with breast cancer. The variable clinical outcomes seen in patients with similar HER2 status, given similar treatments, suggests that the effects of amplification of HER2 can be influenced by other genetic changes. To assess the broader genomic implications of structural changes at the HER2 locus, we investigated relationships between genomic instability and HER2 status in patients with invasive breast cancer. HER2 status was determined using the PathVysion ® assay. DNA was extracted after laser microdissection from the 181 paraffin-embedded HER2 amplified (n = 39) or HER2 negative (n = 142) tumor specimens with sufficient tumor available to perform molecular analysis. Allelic imbalance (AI) was assessed using a panel of microsatellite markers representing 26 chromosomal regions commonly altered in breast cancer. Student t-tests and partial correlations were used to investigate relationships between genomic instability and HER2 status. The frequency of AI was significantly higher (P < 0.005) in HER2 amplified (27%) compared to HER2 negative tumors (19%). Samples with HER2 amplification showed significantly higher levels of AI (P < 0.05) at chromosomes 11q23, 16q22-q24 and 18q21. Partial correlations including ER status and tumor grade supported associations between HER2 status and alterations at 11q13.1, 16q22-q24 and 18q21. The poor prognosis associated with HER2 amplification may be attributed to global genomic instability as cells with high frequencies of chromosomal alterations have been associated with increased cellular proliferation and aggressive behavior. In addition, high levels of DNA damage may render tumor cells refractory to treatment. In addition, specific alterations at chromosomes 11q13, 16q22-q24, and 18q21, all of which have been associated with aggressive tumor behavior, may serve as genetic modifiers to HER2

  4. Genomic instability of osteosarcoma cell lines in culture: impact on the prediction of metastasis relevant genes.

    Science.gov (United States)

    Muff, Roman; Rath, Prisni; Ram Kumar, Ram Mohan; Husmann, Knut; Born, Walter; Baudis, Michael; Fuchs, Bruno

    2015-01-01

    Osteosarcoma is a rare but highly malignant cancer of the bone. As a consequence, the number of established cell lines used for experimental in vitro and in vivo osteosarcoma research is limited and the value of these cell lines relies on their stability during culture. Here we investigated the stability in gene expression by microarray analysis and array genomic hybridization of three low metastatic cell lines and derivatives thereof with increased metastatic potential using cells of different passages. The osteosarcoma cell lines showed altered gene expression during in vitro culture, and it was more pronounced in two metastatic cell lines compared to the respective parental cells. Chromosomal instability contributed in part to the altered gene expression in SAOS and LM5 cells with low and high metastatic potential. To identify metastasis-relevant genes in a background of passage-dependent altered gene expression, genes involved in "Pathways in cancer" that were consistently regulated under all passage comparisons were evaluated. Genes belonging to "Hedgehog signaling pathway" and "Wnt signaling pathway" were significantly up-regulated, and IHH, WNT10B and TCF7 were found up-regulated in all three metastatic compared to the parental cell lines. Considerable instability during culture in terms of gene expression and chromosomal aberrations was observed in osteosarcoma cell lines. The use of cells from different passages and a search for genes consistently regulated in early and late passages allows the analysis of metastasis-relevant genes despite the observed instability in gene expression in osteosarcoma cell lines during culture.

  5. Associations between circulating carotenoids, genomic instability and the risk of high-grade prostate cancer.

    Science.gov (United States)

    Nordström, Tobias; Van Blarigan, Erin L; Ngo, Vy; Roy, Ritu; Weinberg, Vivian; Song, Xiaoling; Simko, Jeffry; Carroll, Peter R; Chan, June M; Paris, Pamela L

    2016-03-01

    Carotenoids are a class of nutrients with antioxidant properties that have been purported to protect against cancer. However, the reported associations between carotenoids and prostate cancer have been heterogeneous and lacking data on interactions with nucleotide sequence variations and genomic biomarkers. To examine the associations between carotenoid levels and the risk of high-grade prostate cancer, also considering antioxidant-related genes and tumor instability. We measured plasma levels of carotenoids and genotyped 20 single nucleotide polymorphisms (SNP) in SOD1, SOD2, SOD3, XRCC1, and OGG1 among 559 men with non-metastatic prostate cancer undergoing radical prostatectomy. We performed copy number analysis in a subset of these men (n = 67) to study tumor instability assessed as Fraction of the Genome Altered (FGA). We examined associations between carotenoids, genotypes, tumor instability and risk of high-grade prostate cancer (Gleason grade ≥ 4 + 3) using logistic and linear regression. Circulating carotenoid levels were inversely associated with the risk of high-grade prostate cancer; odds ratios (OR) and 95% confidence intervals (CI) comparing highest versus lowest quartiles were: 0.34 (95% CI: 0.18-0.66) for α-carotene, 0.31 (95% CI: 0.15-0.63) for β-carotene, 0.55 (0.28-1.08) for lycopene and 0.37 (0.18-0.75) for total carotenoids. SNPs rs25489 in XRCC1, rs699473 in SOD3 and rs1052133 in OGG1 modified these associations for α-carotene, β-carotene and lycopene, respectively (P ≤ 0.05). The proportion of men with a high degree of FGA increased with Gleason Score (P carotenoids at diagnosis, particularly among men carrying specific somatic variations, were inversely associated with risk of high-grade prostate cancer. In exploratory analyses, higher lycopene level was associated with less genomic instability among men with low-grade disease which is novel and supports the hypothesis that lycopene may inhibit progression of

  6. TopBP1/Dpb11 binds DNA anaphase bridges to prevent genome instability.

    Science.gov (United States)

    Germann, Susanne M; Schramke, Vera; Pedersen, Rune Troelsgaard; Gallina, Irene; Eckert-Boulet, Nadine; Oestergaard, Vibe H; Lisby, Michael

    2014-01-06

    DNA anaphase bridges are a potential source of genome instability that may lead to chromosome breakage or nondisjunction during mitosis. Two classes of anaphase bridges can be distinguished: DAPI-positive chromatin bridges and DAPI-negative ultrafine DNA bridges (UFBs). Here, we establish budding yeast Saccharomyces cerevisiae and the avian DT40 cell line as model systems for studying DNA anaphase bridges and show that TopBP1/Dpb11 plays an evolutionarily conserved role in their metabolism. Together with the single-stranded DNA binding protein RPA, TopBP1/Dpb11 binds to UFBs, and depletion of TopBP1/Dpb11 led to an accumulation of chromatin bridges. Importantly, the NoCut checkpoint that delays progression from anaphase to abscission in yeast was activated by both UFBs and chromatin bridges independently of Dpb11, and disruption of the NoCut checkpoint in Dpb11-depleted cells led to genome instability. In conclusion, we propose that TopBP1/Dpb11 prevents accumulation of anaphase bridges via stimulation of the Mec1/ATR kinase and suppression of homologous recombination.

  7. Genomic instability and radiation risk in molecular pathways to colon cancer.

    Directory of Open Access Journals (Sweden)

    Jan Christian Kaiser

    Full Text Available Colon cancer is caused by multiple genomic alterations which lead to genomic instability (GI. GI appears in molecular pathways of microsatellite instability (MSI and chromosomal instability (CIN with clinically observed case shares of about 15-20% and 80-85%. Radiation enhances the colon cancer risk by inducing GI, but little is known about different outcomes for MSI and CIN. Computer-based modelling can facilitate the understanding of the phenomena named above. Comprehensive biological models, which combine the two main molecular pathways to colon cancer, are fitted to incidence data of Japanese a-bomb survivors. The preferred model is selected according to statistical criteria and biological plausibility. Imprints of cell-based processes in the succession from adenoma to carcinoma are identified by the model from age dependences and secular trends of the incidence data. Model parameters show remarkable compliance with mutation rates and growth rates for adenoma, which has been reported over the last fifteen years. Model results suggest that CIN begins during fission of intestinal crypts. Chromosomal aberrations are generated at a markedly elevated rate which favors the accelerated growth of premalignant adenoma. Possibly driven by a trend of Westernization in the Japanese diet, incidence rates for the CIN pathway increased notably in subsequent birth cohorts, whereas rates pertaining to MSI remained constant. An imbalance between number of CIN and MSI cases began to emerge in the 1980s, whereas in previous decades the number of cases was almost equal. The CIN pathway exhibits a strong radio-sensitivity, probably more intensive in men. Among young birth cohorts of both sexes the excess absolute radiation risk related to CIN is larger by an order of magnitude compared to the MSI-related risk. Observance of pathway-specific risks improves the determination of the probability of causation for radiation-induced colon cancer in individual patients

  8. RECQL5 Suppresses Oncogenic JAK2-Induced Replication Stress and Genomic Instability

    Directory of Open Access Journals (Sweden)

    Edwin Chen

    2015-12-01

    Full Text Available JAK2V617F is the most common oncogenic lesion in patients with myeloproliferative neoplasms (MPNs. Despite the ability of JAK2V617F to instigate DNA damage in vitro, MPNs are nevertheless characterized by genomic stability. In this study, we address this paradox by identifying the DNA helicase RECQL5 as a suppressor of genomic instability in MPNs. We report increased RECQL5 expression in JAK2V617F-expressing cells and demonstrate that RECQL5 is required to counteract JAK2V617F-induced replication stress. Moreover, RECQL5 depletion sensitizes JAK2V617F mutant cells to hydroxyurea (HU, a pharmacological inducer of replication stress and the most common treatment for MPNs. Using single-fiber chromosome combing, we show that RECQL5 depletion in JAK2V617F mutant cells impairs replication dynamics following HU treatment, resulting in increased double-stranded breaks and apoptosis. Cumulatively, these findings identify RECQL5 as a critical regulator of genome stability in MPNs and demonstrate that replication stress-associated cytotoxicity can be amplified specifically in JAK2V617F mutant cells through RECQL5-targeted synthetic lethality.

  9. High Genomic Instability Predicts Survival in Metastatic High-Risk Neuroblastoma

    Directory of Open Access Journals (Sweden)

    Sara Stigliani

    2012-09-01

    Full Text Available We aimed to identify novel molecular prognostic markers to better predict relapse risk estimate for children with high-risk (HR metastatic neuroblastoma (NB. We performed genome- and/or transcriptome-wide analyses of 129 stage 4 HR NBs. Children older than 1 year of age were categorized as “short survivors” (dead of disease within 5 years from diagnosis and “long survivors” (alive with an overall survival time ≥ 5 years. We reported that patients with less than three segmental copy number aberrations in their tumor represent a molecularly defined subgroup with a high survival probability within the current HR group of patients. The complex genomic pattern is a prognostic marker independent of NB-associated chromosomal aberrations, i.e., MYCN amplification, 1p and 11q losses, and 17q gain. Integrative analysis of genomic and expression signatures demonstrated that fatal outcome is mainly associated with loss of cell cycle control and deregulation of Rho guanosine triphosphates (GTPases functioning in neuritogenesis. Tumors with MYCN amplification show a lower chromosome instability compared to MYCN single-copy NBs (P = .0008, dominated by 17q gain and 1p loss. Moreover, our results suggest that the MYCN amplification mainly drives disruption of neuronal differentiation and reduction of cell adhesion process involved in tumor invasion and metastasis. Further validation studies are warranted to establish this as a risk stratification for patients.

  10. Occupational exposure to anesthetics leads to genomic instability, cytotoxicity and proliferative changes

    International Nuclear Information System (INIS)

    Souza, Kátina M.; Braz, Leandro G.; Nogueira, Flávia R.; Souza, Marajane B.; Bincoleto, Lahis F.; Aun, Aline G.; Corrente, José E.; Carvalho, Lídia R.; Braz, José Reinaldo C.; Braz, Mariana G.

    2016-01-01

    Highlights: • Anesthesiologists exposed to the most commonly used anesthetic gases were evaluated. • No alterations were detected for lymphocyte DNA damage detected by the comet assay. • Decreased frequencies of basal cells were detected in exfoliated buccal cells (BMCyt). • Increased frequencies of micronucleus and cytotoxicity were observed in BMCyt assay. • Anesthesiologists have genomic instability due to occupational exposure. - Abstract: Data on the genotoxic and mutagenic effects of occupational exposure to the most frequently used volatile anesthetics are limited and controversial. The current study is the first to evaluate genomic instability, cell death and proliferative index in exfoliated buccal cells (EBC) from anesthesiologists. We also evaluated DNA damage and determined the concentrations of the anesthetic gases most commonly used in operating rooms. This study was conducted on physicians who were allocated into two groups: the exposed group, which consisted of anesthesiologists who had been exposed to waste anesthetic gases (isoflurane, sevoflurane, desflurane and nitrous oxide − N 2 O) for at least two years; and the control group, which consisted of non-exposed physicians matched for age, sex and lifestyle with the exposed group. Venous blood and EBC samples were collected from all participants. Basal DNA damage was evaluated in lymphocytes by the comet assay, whereas the buccal micronucleus (MN) cytome (BMCyt) assay was applied to evaluate genotoxic and cytotoxic effects. The concentrations of N 2 O and anesthetics were measured via a portable infrared spectrophotometer. The average concentration of waste gases was greater than 5 parts per million (ppm) for all of the halogenated anesthetics and was more than 170 ppm for N 2 O, expressed as a time-weighted average. There was no significant difference between the groups in relation to lymphocyte DNA damage. The exposed group had higher frequencies of MN, karyorrhexis and pyknosis, and

  11. Occupational exposure to anesthetics leads to genomic instability, cytotoxicity and proliferative changes

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Kátina M.; Braz, Leandro G.; Nogueira, Flávia R.; Souza, Marajane B.; Bincoleto, Lahis F.; Aun, Aline G. [Faculdade de Medicina de Botucatu, UNESP − Univ Estadual Paulista, Departamento de Anestesiologia, Botucatu (Brazil); Corrente, José E.; Carvalho, Lídia R. [Instituto de Biociências de Botucatu, UNESP − Univ Estadual Paulista, Departamento de Bioestatística, Botucatu (Brazil); Braz, José Reinaldo C. [Faculdade de Medicina de Botucatu, UNESP − Univ Estadual Paulista, Departamento de Anestesiologia, Botucatu (Brazil); Braz, Mariana G., E-mail: mgbraz@hotmail.com [Faculdade de Medicina de Botucatu, UNESP − Univ Estadual Paulista, Departamento de Anestesiologia, Botucatu (Brazil)

    2016-09-15

    Highlights: • Anesthesiologists exposed to the most commonly used anesthetic gases were evaluated. • No alterations were detected for lymphocyte DNA damage detected by the comet assay. • Decreased frequencies of basal cells were detected in exfoliated buccal cells (BMCyt). • Increased frequencies of micronucleus and cytotoxicity were observed in BMCyt assay. • Anesthesiologists have genomic instability due to occupational exposure. - Abstract: Data on the genotoxic and mutagenic effects of occupational exposure to the most frequently used volatile anesthetics are limited and controversial. The current study is the first to evaluate genomic instability, cell death and proliferative index in exfoliated buccal cells (EBC) from anesthesiologists. We also evaluated DNA damage and determined the concentrations of the anesthetic gases most commonly used in operating rooms. This study was conducted on physicians who were allocated into two groups: the exposed group, which consisted of anesthesiologists who had been exposed to waste anesthetic gases (isoflurane, sevoflurane, desflurane and nitrous oxide − N{sub 2}O) for at least two years; and the control group, which consisted of non-exposed physicians matched for age, sex and lifestyle with the exposed group. Venous blood and EBC samples were collected from all participants. Basal DNA damage was evaluated in lymphocytes by the comet assay, whereas the buccal micronucleus (MN) cytome (BMCyt) assay was applied to evaluate genotoxic and cytotoxic effects. The concentrations of N{sub 2}O and anesthetics were measured via a portable infrared spectrophotometer. The average concentration of waste gases was greater than 5 parts per million (ppm) for all of the halogenated anesthetics and was more than 170 ppm for N{sub 2}O, expressed as a time-weighted average. There was no significant difference between the groups in relation to lymphocyte DNA damage. The exposed group had higher frequencies of MN, karyorrhexis and

  12. Double-strand break repair-adox: Restoration of suppressed double-strand break repair during mitosis induces genomic instability.

    Science.gov (United States)

    Terasawa, Masahiro; Shinohara, Akira; Shinohara, Miki

    2014-12-01

    Double-strand breaks (DSBs) are one of the severest types of DNA damage. Unrepaired DSBs easily induce cell death and chromosome aberrations. To maintain genomic stability, cells have checkpoint and DSB repair systems to respond to DNA damage throughout most of the cell cycle. The failure of this process often results in apoptosis or genomic instability, such as aneuploidy, deletion, or translocation. Therefore, DSB repair is essential for maintenance of genomic stability. During mitosis, however, cells seem to suppress the DNA damage response and proceed to the next G1 phase, even if there are unrepaired DSBs. The biological significance of this suppression is not known. In this review, we summarize recent studies of mitotic DSB repair and discuss the mechanisms of suppression of DSB repair during mitosis. DSB repair, which maintains genomic integrity in other phases of the cell cycle, is rather toxic to cells during mitosis, often resulting in chromosome missegregation and aberration. Cells have multiple safeguards to prevent genomic instability during mitosis: inhibition of 53BP1 or BRCA1 localization to DSB sites, which is important to promote non-homologous end joining or homologous recombination, respectively, and also modulation of the non-homologous end joining core complex to inhibit DSB repair. We discuss how DSBs during mitosis are toxic and the multiple safeguard systems that suppress genomic instability. © 2014 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.

  13. Genomic instability of osteosarcoma cell lines in culture: impact on the prediction of metastasis relevant genes.

    Directory of Open Access Journals (Sweden)

    Roman Muff

    Full Text Available Osteosarcoma is a rare but highly malignant cancer of the bone. As a consequence, the number of established cell lines used for experimental in vitro and in vivo osteosarcoma research is limited and the value of these cell lines relies on their stability during culture. Here we investigated the stability in gene expression by microarray analysis and array genomic hybridization of three low metastatic cell lines and derivatives thereof with increased metastatic potential using cells of different passages.The osteosarcoma cell lines showed altered gene expression during in vitro culture, and it was more pronounced in two metastatic cell lines compared to the respective parental cells. Chromosomal instability contributed in part to the altered gene expression in SAOS and LM5 cells with low and high metastatic potential. To identify metastasis-relevant genes in a background of passage-dependent altered gene expression, genes involved in "Pathways in cancer" that were consistently regulated under all passage comparisons were evaluated. Genes belonging to "Hedgehog signaling pathway" and "Wnt signaling pathway" were significantly up-regulated, and IHH, WNT10B and TCF7 were found up-regulated in all three metastatic compared to the parental cell lines.Considerable instability during culture in terms of gene expression and chromosomal aberrations was observed in osteosarcoma cell lines. The use of cells from different passages and a search for genes consistently regulated in early and late passages allows the analysis of metastasis-relevant genes despite the observed instability in gene expression in osteosarcoma cell lines during culture.

  14. Distinct Mechanisms of Nuclease-Directed DNA-Structure-Induced Genetic Instability in Cancer Genomes.

    Science.gov (United States)

    Zhao, Junhua; Wang, Guliang; Del Mundo, Imee M; McKinney, Jennifer A; Lu, Xiuli; Bacolla, Albino; Boulware, Stephen B; Zhang, Changsheng; Zhang, Haihua; Ren, Pengyu; Freudenreich, Catherine H; Vasquez, Karen M

    2018-01-30

    Sequences with the capacity to adopt alternative DNA structures have been implicated in cancer etiology; however, the mechanisms are unclear. For example, H-DNA-forming sequences within oncogenes have been shown to stimulate genetic instability in mammals. Here, we report that H-DNA-forming sequences are enriched at translocation breakpoints in human cancer genomes, further implicating them in cancer etiology. H-DNA-induced mutations were suppressed in human cells deficient in the nucleotide excision repair nucleases, ERCC1-XPF and XPG, but were stimulated in cells deficient in FEN1, a replication-related endonuclease. Further, we found that these nucleases cleaved H-DNA conformations, and the interactions of modeled H-DNA with ERCC1-XPF, XPG, and FEN1 proteins were explored at the sub-molecular level. The results suggest mechanisms of genetic instability triggered by H-DNA through distinct structure-specific, cleavage-based replication-independent and replication-dependent pathways, providing critical evidence for a role of the DNA structure itself in the etiology of cancer and other human diseases. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Centrosome Dysfunction Contributes To Chromosome Instability, Chromoanagenesis And Genome Reprograming In Cancer.

    Directory of Open Access Journals (Sweden)

    German A Pihan

    2013-11-01

    Full Text Available The unique ability of centrosomes to nucleate and organize microtubules makes them unrivaled conductors of important interphase processes, such as intracellular payload traffic, cell polarity, cell locomotion, and organization of the immunologic synapse. But it is in mitosis that centrosomes loom large, for they orchestrate, with clockmaker’s precision, the assembly and functioning of the mitotic spindle, ensuring the equal partitioning of the replicated genome into daughter cells. Centrosome dysfunction is inextricably linked to aneuploidy and chromosome instability, both hallmarks of cancer cells. Several aspects of centrosome function in normal and cancer cells have been molecularly characterized during the last two decades, greatly enhancing our mechanistic understanding of this tiny organelle. Whether centrosome defects alone can cause cancer, remains unanswered. Until recently, the aggregate of the evidence had suggested that centrosome dysfunction, by deregulating the fidelity of chromosome segregation, promotes and accelerates the characteristic Darwinian evolution of the cancer genome enabled by increased mutational load and/or decreased DNA repair. Very recent experimental work has shown that missegreated chromosomes resulting from centrosome dysfunction may experience extensive DNA damage, suggesting additional dimensions to the role of centrosomes in cancer. Centrosome dysfunction is particularly prevalent in tumors in which the genome has undergone extensive structural rearrangements and chromosome domain reshuffling. Ongoing gene reshuffling reprograms the genome for continuous growth, survival, and evasion of the immune system. Manipulation of molecular networks controlling centrosome function may soon become a viable target for specific therapeutic intervention in cancer, particularly since normal cells, which lack centrosome alterations, may be spared the toxicity of such therapies.

  16. Warburg effect and translocation-induced genomic instability: two yeast models for cancer cells

    International Nuclear Information System (INIS)

    Tosato, Valentina; Grüning, Nana-Maria; Breitenbach, Michael; Arnak, Remigiusz; Ralser, Markus; Bruschi, Carlo V.

    2013-01-01

    Yeast has been established as an efficient model system to study biological principles underpinning human health. In this review we focus on yeast models covering two aspects of cancer formation and progression (i) the activity of pyruvate kinase (PK), which recapitulates metabolic features of cancer cells, including the Warburg effect, and (ii) chromosome bridge-induced translocation (BIT) mimiking genome instability in cancer. Saccharomyces cerevisiae is an excellent model to study cancer cell metabolism, as exponentially growing yeast cells exhibit many metabolic similarities with rapidly proliferating cancer cells. The metabolic reconfiguration includes an increase in glucose uptake and fermentation, at the expense of respiration and oxidative phosphorylation (the Warburg effect), and involves a broad reconfiguration of nucleotide and amino acid metabolism. Both in yeast and humans, the regulation of this process seems to have a central player, PK, which is up-regulated in cancer, and to occur mostly on a post-transcriptional and post-translational basis. Furthermore, BIT allows to generate selectable translocation-derived recombinants (“translocants”), between any two desired chromosomal locations, in wild-type yeast strains transformed with a linear DNA cassette carrying a selectable marker flanked by two DNA sequences homologous to different chromosomes. Using the BIT system, targeted non-reciprocal translocations in mitosis are easily inducible. An extensive collection of different yeast translocants exhibiting genome instability and aberrant phenotypes similar to cancer cells has been produced and subjected to analysis. In this review, we hence provide an overview upon two yeast cancer models, and extrapolate general principles for mimicking human disease mechanisms in yeast.

  17. WARBURG EFFECT AND TRANSLOCATION-INDUCED GENOMIC INSTABILITY: TWO YEAST MODELS FOR CANCER CELLS

    Directory of Open Access Journals (Sweden)

    Valentina eTosato

    2013-01-01

    Full Text Available Yeast has been established as an efficient model system to study biological principles underpinning human health. In this review we focus on yeast models covering two aspects of cancer formation and progression i the activity of pyruvate kinase (PK, which recapitulates metabolic features of cancer cells, including the Warburg effect, and ii Bridge-Induced chromosome Translocation (BIT mimicking genome instability in cancer. Saccharomyces cerevisiae is an excellent model to study cancer cell metabolism, as exponentially growing yeast cells exhibit many metabolic similarities with rapidly proliferating cancer cells. The metabolic reconfiguration includes an increase in glucose uptake and fermentation, at the expense of respiration and oxidative phosphorylation (the Warburg effect, and involves a broad reconfiguration of nucleotide and amino acid metabolism. Both in yeast and humans, the regulation of this process seems to have a central player, pyruvate kinase, which is up-regulated in cancer, and to occur mostly on a post-transcriptional and posttranslational basis. Furthermore, BIT allows to generate selectable translocation-derived recombinants (translocants, between any two desired chromosomal locations, in wild-type yeast strains transformed with a linear DNA cassette carrying a selectable marker flanked by two DNA sequences homologous to different chromosomes. Using the Bridge-Induced Translocation system, targeted non-reciprocal translocations in mitosis are easily inducible. An extensive collection of different yeast translocants exhibiting genome instability and aberrant phenotypes similar to cancer cells has been produced and subjected to analysis. In this review, we hence provide an overview upon two yeast cancer models, and extrapolate general principles for mimicking human disease mechanisms in yeast.

  18. Warburg effect and translocation-induced genomic instability: two yeast models for cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Tosato, Valentina [International Centre for Genetic Engineering and Biotechnology, Trieste (Italy); Grüning, Nana-Maria [Cambridge System Biology Center, Department of Biochemistry, University of Cambridge, Cambridge (United Kingdom); Breitenbach, Michael [Division of Genetics, Department of Cell Biology, University of Salzburg, Salzburg (Austria); Arnak, Remigiusz [International Centre for Genetic Engineering and Biotechnology, Trieste (Italy); Ralser, Markus [Cambridge System Biology Center, Department of Biochemistry, University of Cambridge, Cambridge (United Kingdom); Bruschi, Carlo V., E-mail: bruschi@icgeb.org [International Centre for Genetic Engineering and Biotechnology, Trieste (Italy)

    2013-01-18

    Yeast has been established as an efficient model system to study biological principles underpinning human health. In this review we focus on yeast models covering two aspects of cancer formation and progression (i) the activity of pyruvate kinase (PK), which recapitulates metabolic features of cancer cells, including the Warburg effect, and (ii) chromosome bridge-induced translocation (BIT) mimiking genome instability in cancer. Saccharomyces cerevisiae is an excellent model to study cancer cell metabolism, as exponentially growing yeast cells exhibit many metabolic similarities with rapidly proliferating cancer cells. The metabolic reconfiguration includes an increase in glucose uptake and fermentation, at the expense of respiration and oxidative phosphorylation (the Warburg effect), and involves a broad reconfiguration of nucleotide and amino acid metabolism. Both in yeast and humans, the regulation of this process seems to have a central player, PK, which is up-regulated in cancer, and to occur mostly on a post-transcriptional and post-translational basis. Furthermore, BIT allows to generate selectable translocation-derived recombinants (“translocants”), between any two desired chromosomal locations, in wild-type yeast strains transformed with a linear DNA cassette carrying a selectable marker flanked by two DNA sequences homologous to different chromosomes. Using the BIT system, targeted non-reciprocal translocations in mitosis are easily inducible. An extensive collection of different yeast translocants exhibiting genome instability and aberrant phenotypes similar to cancer cells has been produced and subjected to analysis. In this review, we hence provide an overview upon two yeast cancer models, and extrapolate general principles for mimicking human disease mechanisms in yeast.

  19. A novel ATM-dependent checkpoint defect distinct from loss of function mutation promotes genomic instability in melanoma.

    Science.gov (United States)

    Spoerri, Loredana; Brooks, Kelly; Chia, KeeMing; Grossman, Gavriel; Ellis, Jonathan J; Dahmer-Heath, Mareike; Škalamera, Dubravka; Pavey, Sandra; Burmeister, Bryan; Gabrielli, Brian

    2016-05-01

    Melanomas have high levels of genomic instability that can contribute to poor disease prognosis. Here, we report a novel defect of the ATM-dependent cell cycle checkpoint in melanoma cell lines that promotes genomic instability. In defective cells, ATM signalling to CHK2 is intact, but the cells are unable to maintain the cell cycle arrest due to elevated PLK1 driving recovery from the arrest. Reducing PLK1 activity recovered the ATM-dependent checkpoint arrest, and over-expressing PLK1 was sufficient to overcome the checkpoint arrest and increase genomic instability. Loss of the ATM-dependent checkpoint did not affect sensitivity to ionizing radiation demonstrating that this defect is distinct from ATM loss of function mutations. The checkpoint defective melanoma cell lines over-express PLK1, and a significant proportion of melanomas have high levels of PLK1 over-expression suggesting this defect is a common feature of melanomas. The inability of ATM to impose a cell cycle arrest in response to DNA damage increases genomic instability. This work also suggests that the ATM-dependent checkpoint arrest is likely to be defective in a higher proportion of cancers than previously expected. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Lack of specificity of chromosome breaks resulting from radiation-induced genomic instability in Chinese hamster cells

    International Nuclear Information System (INIS)

    Trott, K.-R.; Teibe, A.

    1998-01-01

    In V79 Chinese hamster cells, radiation-induced genomic instability results in a persistently increased frequency of micronuclei, dicentric chromosomes and apoptosis and in decreased colony-forming ability. These manifestations of radiation-induced genomic instability may be attributed to an increased rate of chromosome breakage events many generations after irradiation. This chromosomal instability does not seem to be a property which has been inflicted on individual chromosomes at the time of irradiation. Rather, it appears to be secondary to an increased level of non-specific clastogenic factors in the progeny of most if not all irradiated cells. This conclusion is drawn from the observations presented here, that all the chromosomes in surviving V79 cells are involved in the formation of dicentric chromosome aberrations 1 or 2 weeks after irradiation with about equal probability if corrections are made for chromosome length. (orig.)

  1. Genomic Instability: The Driving Force behind Refractory/Relapsing Hodgkin’s Lymphoma

    International Nuclear Information System (INIS)

    Knecht, Hans; Righolt, Christiaan; Mai, Sabine

    2013-01-01

    In classical Hodgkin’s lymphoma (HL) the malignant mononuclear Hodgkin (H) and multinuclear, diagnostic Reed-Sternberg (RS) cells are rare and generally make up <3% of the total cellular mass of the affected lymph nodes. During recent years, the introduction of laser micro-dissection techniques at the single cell level has substantially improved our understanding of the molecular pathogenesis of HL. Gene expression profiling, comparative genomic hybridization analysis, micro-RNA expression profiling and viral oncogene sequencing have deepened our knowledge of numerous facets of H- and RS-cell gene expression deregulation. The question remains whether disturbed signaling pathways and deregulated transcription factors are at the origin of refractory/relapsing Hodgkin’s lymphoma or whether these hallmarks are at least partially related to another major factor. We recently showed that the 3D nuclear organization of telomeres and chromosomes marked the transition from H- to RS-cells in HL cell lines. This transition is associated with progression of telomere dysfunction, shelterin disruption and progression of complex chromosomal rearrangements. We reported analogous findings in refractory/relapsing HL and identified the shelterin proteins TRF1, TRF2 and POT1 as targets of the LMP1 oncogene in post-germinal center B-cells. Here we summarize our findings, including data not previously published, and propose a model in which progressive disruption of nuclear integrity, a form of genomic instability, is the key-player in refractory/relapsing HL. Therapeutic approaches should take these findings into account

  2. Radiation-induced genomic instability: Are epigenetic mechanisms the missing link?

    Energy Technology Data Exchange (ETDEWEB)

    Aypar, Umut; Morgan, William F.; Baulch, Janet E.

    2011-02-01

    Purpose: This review examines the evidence for the hypothesis that epigenetics are involved in the initiation and perpetuation of radiation-induced genomic instability (RIGI). Conclusion: In addition to the extensively studied targeted effects of radiation, it is now apparent that non-targeted delayed effects such as RIGI are also important post-irradiation outcomes. In RIGI, unirradiated progeny cells display phenotypic changes at delayed times after radiation of the parental cell. RIGI is thought to be important in the process of carcinogenesis, however, the mechanism by which this occurs remains to be elucidated. In the genomically unstable clones developed by Morgan and colleagues, radiation-induced mutations, double-strand breaks, or changes in mRNA levels alone could not account for the initiation or perpetuation of RIGI. Since changes in the DNA sequence could not fully explain the mechanism of RIGI, inherited epigenetic changes may be involved. Epigenetics are known to play an important role in many cellular processes and epigenetic aberrations can lead to carcinogenesis. Recent studies in the field of radiation biology suggest that the changes in methylation patterns may be involved in RIGI. Together these clues have led us to hypothesize that epigenetics may be the missing link in understanding the mechanism behind RIGI.

  3. Condensin II mutation causes T-cell lymphoma through tissue-specific genome instability

    Science.gov (United States)

    Woodward, Jessica; Taylor, Gillian C.; Soares, Dinesh C.; Boyle, Shelagh; Sie, Daoud; Read, David; Chathoth, Keerthi; Vukovic, Milica; Tarrats, Nuria; Jamieson, David; Campbell, Kirsteen J.; Blyth, Karen; Acosta, Juan Carlos; Ylstra, Bauke; Arends, Mark J.; Kranc, Kamil R.; Jackson, Andrew P.; Bickmore, Wendy A.

    2016-01-01

    Chromosomal instability is a hallmark of cancer, but mitotic regulators are rarely mutated in tumors. Mutations in the condensin complexes, which restructure chromosomes to facilitate segregation during mitosis, are significantly enriched in cancer genomes, but experimental evidence implicating condensin dysfunction in tumorigenesis is lacking. We report that mice inheriting missense mutations in a condensin II subunit (Caph2nes) develop T-cell lymphoma. Before tumors develop, we found that the same Caph2 mutation impairs ploidy maintenance to a different extent in different hematopoietic cell types, with ploidy most severely perturbed at the CD4+CD8+ T-cell stage from which tumors initiate. Premalignant CD4+CD8+ T cells show persistent catenations during chromosome segregation, triggering DNA damage in diploid daughter cells and elevated ploidy. Genome sequencing revealed that Caph2 single-mutant tumors are near diploid but carry deletions spanning tumor suppressor genes, whereas P53 inactivation allowed Caph2 mutant cells with whole-chromosome gains and structural rearrangements to form highly aggressive disease. Together, our data challenge the view that mitotic chromosome formation is an invariant process during development and provide evidence that defective mitotic chromosome structure can promote tumorigenesis. PMID:27737961

  4. Radiation Bystander Effects Mechanism

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    Shokohzaman Soleymanifard

    2009-06-01

    Full Text Available Introduction: Radiation Induced Bystander Effect (RIBE which cause radiation effects in non-irradiated cells, has challenged the principle according to which radiation traversal through the nucleus of a cell is necessary for producing biological responses. What is the mechanism of this phenomenon? To have a better understanding of this rather ambiguous concept substantial number of original and reviewed article were carefully examined. Results: Irradiated cells release molecules which can propagate in cell environment and/or transmit through gap junction intercellular communication. These molecules can reach to non-irradiated cells and transmit bystander signals. In many investigations, it has been confirmed that these molecules are growth factors, cytokines, nitric oxide and free radicals like reactive oxygen species (ROS. Transmission of by stander signal to neighboring cells persuades them to produce secondary growth factors which in their turn cause further cell injuries. Some investigators suggest, organelles other than nucleus (mitochondria and cell membrane are the origin of these signals.  There is another opinion which suggests double strand breaks (DSB are not directly generated in bystander cells, rather they are due to smaller damage like single strand breaks which accumulate and end up to DSB. Although bystander mechanisms have not been exactly known, it can be confirmed that multiple mechanisms and various pathways are responsible for this effect. Cell type, radiation type, experimental conditions and end points identify the dominant mechanism. Conclusion: Molecules and pathways which are responsible for RIBE, also cause systemic responses to other non-irradiation stresses. So RIBE is a kind of systemic stress or innate immune responses, which are performed by cell microenvironment. Irradiated cells and their signals are components of microenvironment for creating bystander effects.

  5. Significance of genomic instability in breast cancer in atomic bomb survivors: analysis of microarray-comparative genomic hybridization

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    Oikawa Masahiro

    2011-12-01

    Full Text Available Abstract Background It has been postulated that ionizing radiation induces breast cancers among atomic bomb (A-bomb survivors. We have reported a higher incidence of HER2 and C-MYC oncogene amplification in breast cancers from A-bomb survivors. The purpose of this study was to clarify the effect of A-bomb radiation exposure on genomic instability (GIN, which is an important hallmark of carcinogenesis, in archival formalin-fixed paraffin-embedded (FFPE tissues of breast cancer by using microarray-comparative genomic hybridization (aCGH. Methods Tumor DNA was extracted from FFPE tissues of invasive ductal cancers from 15 survivors who were exposed at 1.5 km or less from the hypocenter and 13 calendar year-matched non-exposed patients followed by aCGH analysis using a high-density oligonucleotide microarray. The total length of copy number aberrations (CNA was used as an indicator of GIN, and correlation with clinicopathological factors were statistically tested. Results The mean of the derivative log ratio spread (DLRSpread, which estimates the noise by calculating the spread of log ratio differences between consecutive probes for all chromosomes, was 0.54 (range, 0.26 to 1.05. The concordance of results between aCGH and fluorescence in situ hybridization (FISH for HER2 gene amplification was 88%. The incidence of HER2 amplification and histological grade was significantly higher in the A-bomb survivors than control group (P = 0.04, respectively. The total length of CNA tended to be larger in the A-bomb survivors (P = 0.15. Correlation analysis of CNA and clinicopathological factors revealed that DLRSpread was negatively correlated with that significantly (P = 0.034, r = -0.40. Multivariate analysis with covariance revealed that the exposure to A-bomb was a significant (P = 0.005 independent factor which was associated with larger total length of CNA of breast cancers. Conclusions Thus, archival FFPE tissues from A-bomb survivors are useful for

  6. Significance of genomic instability in breast cancer in atomic bomb survivors: analysis of microarray-comparative genomic hybridization

    International Nuclear Information System (INIS)

    Oikawa, Masahiro; Yoshiura, Koh-ichiro; Kondo, Hisayoshi; Miura, Shiro; Nagayasu, Takeshi; Nakashima, Masahiro

    2011-01-01

    It has been postulated that ionizing radiation induces breast cancers among atomic bomb (A-bomb) survivors. We have reported a higher incidence of HER2 and C-MYC oncogene amplification in breast cancers from A-bomb survivors. The purpose of this study was to clarify the effect of A-bomb radiation exposure on genomic instability (GIN), which is an important hallmark of carcinogenesis, in archival formalin-fixed paraffin-embedded (FFPE) tissues of breast cancer by using microarray-comparative genomic hybridization (aCGH). Tumor DNA was extracted from FFPE tissues of invasive ductal cancers from 15 survivors who were exposed at 1.5 km or less from the hypocenter and 13 calendar year-matched non-exposed patients followed by aCGH analysis using a high-density oligonucleotide microarray. The total length of copy number aberrations (CNA) was used as an indicator of GIN, and correlation with clinicopathological factors were statistically tested. The mean of the derivative log ratio spread (DLRSpread), which estimates the noise by calculating the spread of log ratio differences between consecutive probes for all chromosomes, was 0.54 (range, 0.26 to 1.05). The concordance of results between aCGH and fluorescence in situ hybridization (FISH) for HER2 gene amplification was 88%. The incidence of HER2 amplification and histological grade was significantly higher in the A-bomb survivors than control group (P = 0.04, respectively). The total length of CNA tended to be larger in the A-bomb survivors (P = 0.15). Correlation analysis of CNA and clinicopathological factors revealed that DLRSpread was negatively correlated with that significantly (P = 0.034, r = -0.40). Multivariate analysis with covariance revealed that the exposure to A-bomb was a significant (P = 0.005) independent factor which was associated with larger total length of CNA of breast cancers. Thus, archival FFPE tissues from A-bomb survivors are useful for genome-wide aCGH analysis. Our results suggested that A

  7. Significance of genomic instability in breast cancer in atomic bomb survivors: analysis of microarray-comparative genomic hybridization.

    Science.gov (United States)

    Oikawa, Masahiro; Yoshiura, Koh-ichiro; Kondo, Hisayoshi; Miura, Shiro; Nagayasu, Takeshi; Nakashima, Masahiro

    2011-12-07

    It has been postulated that ionizing radiation induces breast cancers among atomic bomb (A-bomb) survivors. We have reported a higher incidence of HER2 and C-MYC oncogene amplification in breast cancers from A-bomb survivors. The purpose of this study was to clarify the effect of A-bomb radiation exposure on genomic instability (GIN), which is an important hallmark of carcinogenesis, in archival formalin-fixed paraffin-embedded (FFPE) tissues of breast cancer by using microarray-comparative genomic hybridization (aCGH). Tumor DNA was extracted from FFPE tissues of invasive ductal cancers from 15 survivors who were exposed at 1.5 km or less from the hypocenter and 13 calendar year-matched non-exposed patients followed by aCGH analysis using a high-density oligonucleotide microarray. The total length of copy number aberrations (CNA) was used as an indicator of GIN, and correlation with clinicopathological factors were statistically tested. The mean of the derivative log ratio spread (DLRSpread), which estimates the noise by calculating the spread of log ratio differences between consecutive probes for all chromosomes, was 0.54 (range, 0.26 to 1.05). The concordance of results between aCGH and fluorescence in situ hybridization (FISH) for HER2 gene amplification was 88%. The incidence of HER2 amplification and histological grade was significantly higher in the A-bomb survivors than control group (P = 0.04, respectively). The total length of CNA tended to be larger in the A-bomb survivors (P = 0.15). Correlation analysis of CNA and clinicopathological factors revealed that DLRSpread was negatively correlated with that significantly (P = 0.034, r = -0.40). Multivariate analysis with covariance revealed that the exposure to A-bomb was a significant (P = 0.005) independent factor which was associated with larger total length of CNA of breast cancers. Thus, archival FFPE tissues from A-bomb survivors are useful for genome-wide aCGH analysis. Our results suggested that A

  8. Mechanisms and biological importance of photon-induced bystander responses. Do they have an impact on low-dose radiation responses

    International Nuclear Information System (INIS)

    Tomita, Masanori; Maeda, Munetoshi

    2015-01-01

    Elucidating the biological effect of low linear energy transfer (LET), low-dose and/or low-dose-rate ionizing radiation is essential in ensuring radiation safety. Over the past two decades, non-targeted effects, which are not only a direct consequence of radiation-induced initial lesions produced in cellular DNA but also of intra- and inter-cellular communications involving both targeted and non-targeted cells, have been reported and are currently defining a new paradigm in radiation biology. These effects include radiation-induced adaptive response, low-dose hypersensitivity, genomic instability, and radiation-induced bystander response (RIBR). RIBR is generally defined as a cellular response that is induced in non-irradiated cells that receive bystander signals from directly irradiated cells. RIBR could thus play an important biological role in low-dose irradiation conditions. However, this suggestion was mainly based on findings obtained using high-LET charged-particle radiations. The human population (especially the Japanese, who are exposed to lower doses of radon than the world average) is more frequently exposed to low-LET photons (X-rays or γ-rays) than to high-LET charged-particle radiation on a daily basis. There are currently a growing number of reports describing a distinguishing feature between photon-induced bystander response and high-LET RIBR. In particular, photon-induced by-stander response is strongly influenced by irradiation dose, the irradiated region of the targeted cells, and p53 status. The present review focuses on the photon-induced bystander response, and discusses its impact on the low-dose radiation effect. (author)

  9. Genomic instability induced by 137Cs γ-ray irradiation in CHL surviving cells

    International Nuclear Information System (INIS)

    Yue Jingyin; Liu Bingchen; Wu Hongying; Zhou Jiwen; Mu Chuanjie

    1999-01-01

    Objective: To study in parallel several possible manifestations of instability of surviving CHL cells after irradiation, namely the frequencies of mutation at locus, micronuclei and apoptosis. Methods: The frequencies of mutation at HGPRT locus, micronuclei and apoptosis were assayed at various times in surviving cells irradiated with γ-rays. Results: The surviving cells showed a persistently increased frequency of mutation at the HGPRT locus after irradiation until 53 days. Mutant fraction as high as 10 -4 was scored, tens of times higher than those assayed in control cells studied in parallel. The frequency of bi nucleated cells with micronuclei determined within 24 hours after irradiation increased with dose and reached a peak value of (26.58 +- 2.48)% at 3 Gy, decreasing at higher doses to a plateau around 20%. The micronucleus frequency decreased steeply to about (14.47 +- 2.39)% within the first 3 days post-irradiation, and fluctuated at around 10% up to 56 days post-irradiation. The delayed efficiency of irradiated cells was significantly decreased. The frequency of apoptosis peaked about (24.90 +- 4.72)% at 10 Gy 48 h post-irradiation (γ-ray dose between 3-10 Gy) and then decreased to about 12% within 3 days. It was significantly higher than in control cells until 14 days. Conclusions: It shows that genomic instability induced by radiation can be transmitted to the progeny of surviving cells and may take many forms of expression such as lethal mutation, chromosome aberrations, gene mutation, etc

  10. A mutation in the centriole-associated protein centrin causes genomic instability via increased chromosome loss in Chlamydomonas reinhardtii

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    Marshall Wallace F

    2005-05-01

    Full Text Available Abstract Background The role of centrioles in mitotic spindle function remains unclear. One approach to investigate mitotic centriole function is to ask whether mutation of centriole-associated proteins can cause genomic instability. Results We addressed the role of the centriole-associated EF-hand protein centrin in genomic stability using a Chlamydomonas reinhardtii centrin mutant that forms acentriolar bipolar spindles and lacks the centrin-based rhizoplast structures that join centrioles to the nucleus. Using a genetic assay for loss of heterozygosity, we found that this centrin mutant showed increased genomic instability compared to wild-type cells, and we determined that the increase in genomic instability was due to a 100-fold increase in chromosome loss rates compared to wild type. Live cell imaging reveals an increased rate in cell death during G1 in haploid cells that is consistent with an elevated rate of chromosome loss, and analysis of cell death versus centriole copy number argues against a role for multipolar spindles in this process. Conclusion The increased chromosome loss rates observed in a centrin mutant that forms acentriolar spindles suggests a role for centrin protein, and possibly centrioles, in mitotic fidelity.

  11. [Instability and sensitivity of the genome of healthy children in Magnitogorsk].

    Science.gov (United States)

    Ingel', F I; Krivtsova, E K; Iurtseva, N A; Antipanova, N A; Legostaeva, T B

    2013-01-01

    Problem of the influence of factors of the industrial city on the hereditary apparatus of its residents has not been fully resolved, because of traditionally in such studies only the pollution of environment components is taken into account. However the existence of a set of contributing socialfactors that modify the genotoxic effects ofpollution, requires the creation of a new methodology for genetic and toxicological studies. For this purpose, in Magnitogorsk, where one of Russia's largest steel plants is located, we conducted a comprehensive survey, whose tasks included the analysis of the influence of the complex of exogenous and endogenous factors on the genome of children. In this publication there are presented the results of the fifth fragment of this work - the analysis of instability and individual sensitivity of the genome of 166 children of 5-7 years, residing in two districts of Magnitogorsk: around the steel plant and on the opposite bank of Ural river, where there are no large-scale industrial enterprises. The study was conducted in the micronucleus test on peripheral blood lymphocytes cultured with cytochalasin B. For assessment of individual sensitivity of genome blood cultures were exposed to standard N-methyl-N-nitro-N-nitrosoguanidine (MNNG) mutagen. Cytogenetic analysis was performed in binucleated cells accordingly to international protocol, as well as with the use of an extended protocol including 32 indices. Average group frequency of binuclear cells with micronuclei (0.5-0.7%) were found not differ from the levels defined in children residing in Europe, and not differ between areas of the town. However the extended protocol of cytogenetic analysis discovered that the real frequency of dividing cells with lesions in blood cultures of children was 1,49-1,66%. Higher spontaneous proliferative activity of the cells and the frequency of dividing cells with injuries were found in blood cultures of children residing in settlements around the

  12. Vanguards of paradigm shift in radiation biology. Radiation-induced adaptive and bystander responses

    International Nuclear Information System (INIS)

    Matsumoto, Hideki; Hamada, Nobuyuki; Kobayashi, Yasuhiko; Takahashi, Akihisa; Ohnishi, Takeo

    2007-01-01

    The risks of exposure to low dose ionizing radiation (below 100 mSv) are estimated by extrapolating from data obtained after exposure to high dose radiation, using a linear no-threshold model (LNT model). However, the validity of using this dose-response model is controversial because evidence accumulated over the past decade has indicated that living organisms, including humans, respond differently to low dose/low dose-rate radiation than they do to high dose/high dose-rate radiation. In other words, there are accumulated findings which cannot be explained by the classical ''target theory'' of radiation biology. The radioadaptive response, radiation-induced bystander effects, low-dose radio-hypersensitivity, and genomic instability are specifically observed in response to low dose/low dose-rate radiation, and the mechanisms underlying these responses often involve biochemical/molecular signals that respond to targeted and non-targeted events. Recently, correlations between the radioadaptive and bystander responses have been increasingly reported. The present review focuses on the latter two phenomena by summarizing observations supporting their existence, and discussing the linkage between them from the aspect of production of reactive oxygen and nitrogen species. (author)

  13. Cadmium-induced genomic instability in Arabidopsis: Molecular toxicological biomarkers for early diagnosis of cadmium stress.

    Science.gov (United States)

    Wang, Hetong; He, Lei; Song, Jie; Cui, Weina; Zhang, Yanzhao; Jia, Chunyun; Francis, Dennis; Rogers, Hilary J; Sun, Lizong; Tai, Peidong; Hui, Xiujuan; Yang, Yuesuo; Liu, Wan

    2016-05-01

    Microsatellite instability (MSI) analysis, random-amplified polymorphic DNA (RAPD), and methylation-sensitive arbitrarily primed PCR (MSAP-PCR) are methods to evaluate the toxicity of environmental pollutants in stress-treated plants and human cancer cells. Here, we evaluate these techniques to screen for genetic and epigenetic alterations of Arabidopsis plantlets exposed to 0-5.0 mg L(-1) cadmium (Cd) for 15 d. There was a substantial increase in RAPD polymorphism of 24.5, and in genomic methylation polymorphism of 30.5-34.5 at CpG and of 14.5-20 at CHG sites under Cd stress of 5.0 mg L(-1) by RAPD and of 0.25-5.0 mg L(-1) by MSAP-PCR, respectively. However, only a tiny increase of 1.5 loci by RAPD occurred under Cd stress of 4.0 mg L(-1), and an additional high dose (8.0 mg L(-1)) resulted in one repeat by MSI analysis. MSAP-PCR detected the most significant epigenetic modifications in plantlets exposed to Cd stress, and the patterns of hypermethylation and polymorphisms were consistent with inverted U-shaped dose responses. The presence of genomic methylation polymorphism in Cd-treated seedlings, prior to the onset of RAPD polymorphism, MSI and obvious growth effects, suggests that these altered DNA methylation loci are the most sensitive biomarkers for early diagnosis and risk assessment of genotoxic effects of Cd pollution in ecotoxicology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Susceptibility to bystander DNA damage is influenced by replication and transcriptional activity

    Science.gov (United States)

    Dickey, Jennifer S.; Baird, Brandon J.; Redon, Christophe E.; Avdoshina, Valeriya; Palchik, Guillermo; Wu, Junfang; Kondratyev, Alexei; Bonner, William M.; Martin, Olga A.

    2012-01-01

    Direct cellular DNA damage may lead to genome destabilization in unexposed, bystander, cells sharing the same milieu with directly damaged cells by means of the bystander effect. One proposed mechanism involves double strand break (DSB) formation in S phase cells at sites of single strand lesions in the DNA of replication complexes, which has a more open structure compared with neighboring DNA. The DNA in transcription complexes also has a more open structure, and hence may be susceptible to bystander DSB formation from single strand lesions. To examine whether transcription predisposes non-replicating cells to bystander effect-induced DNA DSBs, we examined two types of primary cells that exhibit high levels of transcription in the absence of replication, rat neurons and human lymphocytes. We found that non-replicating bystander cells with high transcription rates exhibited substantial levels of DNA DSBs, as monitored by γ-H2AX foci formation. Additionally, as reported in proliferating cells, TGF-β and NO were found to mimic bystander effects in cell populations lacking DNA synthesis. These results indicate that cell vulnerability to bystander DSB damage may result from transcription as well as replication. The findings offer insights into which tissues may be vulnerable to bystander genomic destabilization in vivo. PMID:22941641

  15. Complex DNA Damage: A Route to Radiation-Induced Genomic Instability and Carcinogenesis

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    Ifigeneia V. Mavragani

    2017-07-01

    Full Text Available Cellular effects of ionizing radiation (IR are of great variety and level, but they are mainly damaging since radiation can perturb all important components of the cell, from the membrane to the nucleus, due to alteration of different biological molecules ranging from lipids to proteins or DNA. Regarding DNA damage, which is the main focus of this review, as well as its repair, all current knowledge indicates that IR-induced DNA damage is always more complex than the corresponding endogenous damage resulting from endogenous oxidative stress. Specifically, it is expected that IR will create clusters of damage comprised of a diversity of DNA lesions like double strand breaks (DSBs, single strand breaks (SSBs and base lesions within a short DNA region of up to 15–20 bp. Recent data from our groups and others support two main notions, that these damaged clusters are: (1 repair resistant, increasing genomic instability (GI and malignant transformation and (2 can be considered as persistent “danger” signals promoting chronic inflammation and immune response, causing detrimental effects to the organism (like radiation toxicity. Last but not least, the paradigm shift for the role of radiation-induced systemic effects is also incorporated in this picture of IR-effects and consequences of complex DNA damage induction and its erroneous repair.

  16. Tertiary Epimutations – A Novel Aspect of Epigenetic Transgenerational Inheritance Promoting Genome Instability

    Science.gov (United States)

    McCarrey, John R.; Lehle, Jake D.; Raju, Seetha S.; Wang, Yufeng; Nilsson, Eric E.; Skinner, Michael K.

    2016-01-01

    Exposure to environmental factors can induce the epigenetic transgenerational inheritance of disease. Alterations to the epigenome termed “epimutations” include “primary epimutations” which are epigenetic alterations in the absence of genetic change and “secondary epimutations” which form following an initial genetic change. To determine if secondary epimutations contribute to transgenerational transmission of disease following in utero exposure to the endocrine disruptor vinclozolin, we exposed pregnant female rats carrying the lacI mutation-reporter transgene to vinclozolin and assessed the frequency of mutations in kidney tissue and sperm recovered from F1 and F3 generation progeny. Our results confirm that vinclozolin induces primary epimutations rather than secondary epimutations, but also suggest that some primary epimutations can predispose a subsequent accelerated accumulation of genetic mutations in F3 generation descendants that have the potential to contribute to transgenerational phenotypes. We therefore propose the existence of “tertiary epimutations” which are initial primary epimutations that promote genome instability leading to an accelerated accumulation of genetic mutations. PMID:27992467

  17. Chromosomal Replication Complexity: A Novel DNA Metrics and Genome Instability Factor.

    Directory of Open Access Journals (Sweden)

    Andrei Kuzminov

    2016-10-01

    Full Text Available As the ratio of the copy number of the most replicated to the unreplicated regions in the same chromosome, the definition of chromosomal replication complexity (CRC appears to leave little room for variation, being either two during S-phase or one otherwise. However, bacteria dividing faster than they replicate their chromosome spike CRC to four and even eight. A recent experimental inquiry about the limits of CRC in Escherichia coli revealed two major reasons to avoid elevating it further: (i increased chromosomal fragmentation and (ii complications with subsequent double-strand break repair. Remarkably, examples of stable elevated CRC in eukaryotic chromosomes are well known under various terms like "differential replication," "underreplication," "DNA puffs," "onion-skin replication," or "re-replication" and highlight the phenomenon of static replication fork (sRF. To accurately describe the resulting "amplification by overinitiation," I propose a new term: "replification" (subchromosomal overreplication. In both prokaryotes and eukaryotes, replification, via sRF processing, causes double-strand DNA breaks and, with their repair elevating chromosomal rearrangements, represents a novel genome instability factor. I suggest how static replication bubbles could be stabilized and speculate that some tandem duplications represent such persistent static bubbles. Moreover, I propose how static replication bubbles could be transformed into tandem duplications, double minutes, or inverted triplications. Possible experimental tests of these models are discussed.

  18. Estimation of low-dose radiation-responsive proteins in the absence of genomic instability in normal human fibroblast cells.

    Science.gov (United States)

    Yim, Ji-Hye; Yun, Jung Mi; Kim, Ji Young; Nam, Seon Young; Kim, Cha Soon

    2017-11-01

    Low-dose radiation has various biological effects such as adaptive responses, low-dose hypersensitivity, as well as beneficial effects. However, little is known about the particular proteins involved in these effects. Here, we sought to identify low-dose radiation-responsive phosphoproteins in normal fibroblast cells. We assessed genomic instability and proliferation of fibroblast cells after γ-irradiation by γ-H2AX foci and micronucleus formation analyses and BrdU incorporation assay, respectively. We screened fibroblast cells 8 h after low-dose (0.05 Gy) γ-irradiation using Phospho Explorer Antibody Microarray and validated two differentially expressed phosphoproteins using Western blotting. Cell proliferation proceeded normally in the absence of genomic instability after low-dose γ-irradiation. Phospho antibody microarray analysis and Western blotting revealed increased expression of two phosphoproteins, phospho-NFκB (Ser536) and phospho-P70S6K (Ser418), 8 h after low-dose radiation. Our findings suggest that low-dose radiation of normal fibroblast cells activates the expression of phospho-NFκB (Ser536) and phospho-P70S6K (Ser418) in the absence of genomic instability. Therefore, these proteins may be involved in DNA damage repair processes.

  19. Bystanders Are the Key to Stopping Bullying

    Science.gov (United States)

    Padgett, Sharon; Notar, Charles E.

    2013-01-01

    Bullying is the dominance over another. Bullying occurs when there is an audience. Peer bystanders provide an audience 85% of instances of bullying. If you remove the audience bullying should stop. The article is a review of literature (2002-2013) on the role of bystanders; importance of bystanders; why bystanders behave as they do; resources to…

  20. Heavy-ion radiation induced bystander effect in mice

    Science.gov (United States)

    Liang, Shujian; Sun, Yeqing; Zhang, Meng; Wang, Wei; Cui, Changna

    2012-07-01

    Radiation-induced bystander effect is defined as the induction of damage in neighboring non-hit cells by signals released from directly-irradiated cells. Recently, Low dose of high LET radiation induced bystander effects in vivo have been reported more and more. It has been indicated that radiation induced bystander effect was localized not only in bystander tissues but also in distant organs. Genomic, epigenetic, metabolomics and proteomics play significant roles in regulating heavy-ion radiation stress responses in mice. To identify the molecular mechanism that underlies bystander effects of heavy-ion radiation, the male mice head were exposed to 2000mGy dose of 12C heavy-ion radiation and the distant organ liver was detected on 1h, 6h, 12h and 24h after radiation, respectively. MSAP was used to monitor the level of polymorphic DNA methylation changes. The results show that heavy-ion irradiate mouse head can induce liver DNA methylation changes significantly. The percent of DNA methylation changes are time-dependent and highest at 6h after radiation. We also prove that the hypo-methylation changes on 1h and 6h after irradiation. But the expression level of DNA methyltransferase DNMT3a is not changed. UPLC/Synapt HDMS G2 was employed to detect the proteomics of bystander liver 1h after irradiation. 64 proteins are found significantly different between treatment and control group. GO process show that six of 64 which were unique in irradiation group are associated with apoptosis and DNA damage response. The results suggest that mice head exposed to heavy-ion radiation can induce damage and methylation pattern changed in distant organ liver. Moreover, our findings are important to understand the molecular mechanism of radiation induced bystander effects in vivo.

  1. Clonal chromosomal and genomic instability during human multipotent mesenchymal stromal cells long-term culture.

    Directory of Open Access Journals (Sweden)

    Victoria Nikitina

    Full Text Available Spontaneous mutagenesis often leads to appearance of genetic changes in cells. Although human multipotent mesenchymal stromal cells (hMSC are considered as genetically stable, there is a risk of genomic and structural chromosome instability and, therefore, side effects of cell therapy associated with long-term effects. In this study, the karyotype, genetic variability and clone formation analyses have been carried out in the long-term culture MSC from human gingival mucosa.The immunophenotype of MSC has been examined using flow cytofluorometry and short tandem repeat (STR analysis has been carried out for authentication. The karyotype has been examined using GTG staining and mFISH, while the assessment of the aneuploidy 8 frequency has been performed using centromere specific chromosome FISH probes in interphase cells.The immunophenotype and STR loci combination did not change during the process of cultivation. From passage 23 the proliferative activity of cultured MSCs was significantly reduced. From passage 12 of cultivation, clones of cells with stable chromosome aberrations have been identified and the biggest of these (12% are tetrasomy of chromosome 8. The random genetic and structural chromosomal aberrations and the spontaneous level of chromosomal aberrations in the hMSC long-term cultures were also described.The spectrum of spontaneous chromosomal aberrations in MSC long-term cultivation has been described. Clonal chromosomal aberrations have been identified. A clone of cells with tetrasomy 8 has been detected in passage 12 and has reached the maximum size by passage 18 before and decreased along with the reduction of proliferative activity of cell line by passage 26. At later passages, the MSC line exhibited a set of cells with structural variants of the karyotype with a preponderance of normal diploid cells. The results of our study strongly suggest a need for rigorous genetic analyses of the clone formation in cultured MSCs before

  2. Preferential retrotransposition in aging yeast mother cells is correlated with increased genome instability.

    Science.gov (United States)

    Patterson, Melissa N; Scannapieco, Alison E; Au, Pak Ho; Dorsey, Savanna; Royer, Catherine A; Maxwell, Patrick H

    2015-10-01

    Retrotransposon expression or mobility is increased with age in multiple species and could promote genome instability or altered gene expression during aging. However, it is unclear whether activation of retrotransposons during aging is an indirect result of global changes in chromatin and gene regulation or a result of retrotransposon-specific mechanisms. Retromobility of a marked chromosomal Ty1 retrotransposon in Saccharomyces cerevisiae was elevated in mother cells relative to their daughter cells, as determined by magnetic cell sorting of mothers and daughters. Retromobility frequencies in aging mother cells were significantly higher than those predicted by cell age and the rate of mobility in young populations, beginning when mother cells were only several generations old. New Ty1 insertions in aging mothers were more strongly correlated with gross chromosome rearrangements than in young cells and were more often at non-preferred target sites. Mother cells were more likely to have high concentrations and bright foci of Ty1 Gag-GFP than their daughter cells. Levels of extrachromosomal Ty1 cDNA were also significantly higher in aged mother cell populations than their daughter cell populations. These observations are consistent with a retrotransposon-specific mechanism that causes retrotransposition to occur preferentially in yeast mother cells as they begin to age, as opposed to activation by phenotypic changes associated with very old age. These findings will likely be relevant for understanding retrotransposons and aging in many organisms, based on similarities in regulation and consequences of retrotransposition in diverse species. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. MRC5 and QU-DB bystander cells can produce bystander factors and induce radiation bystander effect

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    Mohammad Taghi Bahreyni Toossi

    2014-01-01

    Full Text Available Radiation damages initiated by radiation-induced bystander effect (RIBE are not limited to the first or immediate neighbors of the irradiated cells, but the effects have been observed in the cells far from the irradiation site. It has been postulated that bystander cells, by producing bystander factors, are actively involved in the propagation of bystander effect in the regions beyond the initial irradiated site. Current study was planned to test the hypothesis. MRC5 and QU-DB cell lines were irradiated, and successive medium transfer technique was performed to induce bystander effects in two bystander cell groups. Conditioned medium extracted from the target cells was transferred to the bystander cells (first bystander cells. After one hour, conditioned medium was substituted by fresh medium. Two hours later, the fresh medium was transferred to a second group of non-irradiated cells (second bystander cells. Micronucleated cells (MC were counted to quantify damages induced in the first and second bystander cell groups. Radiation effect was observed in the second bystander cells as well as in the first ones. Statistical analyses revealed that the number of MC in second bystander subgroups was significantly more than the corresponding value observed in control groups, but in most cases it was equal to the number of MC observed in the first bystander cells. MRC5 and QU-DB bystander cells can produce and release bystander signals in the culture medium and affect non-irradiated cells. Therefore, they may contribute to the RIBE propagation.

  4. Bystander or No Bystander for Gene Directed Enzyme Prodrug Therapy

    Directory of Open Access Journals (Sweden)

    Adam V. Patterson

    2009-11-01

    Full Text Available Gene directed enzyme prodrug therapy (GDEPT of cancer aims to improve the selectivity of chemotherapy by gene transfer, thus enabling target cells to convert nontoxic prodrugs to cytotoxic drugs. A zone of cell kill around gene-modified cells due to transfer of toxic metabolites, known as the bystander effect, leads to tumour regression. Here we discuss the implications of either striving for a strong bystander effect to overcome poor gene transfer, or avoiding the bystander effect to reduce potential systemic effects, with the aid of three successful GDEPT systems. This review concentrates on bystander effects and drug development with regard to these enzyme prodrug combinations, namely herpes simplex virus thymidine kinase (HSV-TK with ganciclovir (GCV, cytosine deaminase (CD from bacteria or yeast with 5-fluorocytodine (5-FC, and bacterial nitroreductase (NfsB with 5-(azaridin-1-yl-2,4-dinitrobenzamide (CB1954, and their respective derivatives.

  5. [Study of genome instability using DNA fingerprinting of the offspring of male mice subjected to chronic low dose gamma irradiation].

    Science.gov (United States)

    Bezlepkin, V G; Vasil'eva, G V; Lomaeva, M G; Sirota, N P; Gaziev, A I

    2000-01-01

    By a polymerase chain reaction with an arbitrary primer (AP-PCR), the possibility of transmission of genome instability to somatic cells of the offspring (F1 generation) from male parents of mice exposed to chronic low-level gamma-radiation was studied. Male BALB/c mice 15 days after exposure to 10-50 cGy were mated with unirradiated females. Biopsies were taken from tale tips of two month-old offspring mice and DNA was isolated. The primer in the AP-PCR was a 20-mer oligonucleotide flanking the microsatellite locus Atp1b2 on chromosome 11 of the mouse. A comparative analysis of individual fingerprints of AP-PCR products on DNA-templates from the offspring of irradiated and unirradiated male mice revealed an increased variability of microsatellite-associated sequences in the genome of the offspring of the males exposed to 25 and 50 cGy. The DNA-fingerprints of the offspring of male mice exposed to chronic irradiation with the doses 10 and 25 cGy 15 days before fertilization (at the post-meiotic stage of spermatogenesis) showed an increased frequency of "non-parent bands". The results of the study point to the possibility of transmission to the offspring somatic cells of changes increasing genome instability from male parents exposed to chronic low-level radiation prior to fertilization.

  6. Non-homologous end-joining genes are not inactivated in human radiation-induced sarcomas with genomic instability

    International Nuclear Information System (INIS)

    Lefevre, S.H.; Coquelle, A.; Gonin-Laurent, N.

    2005-01-01

    DNA double-strand break (DSB) repair pathways are implicated in the maintenance of genomic stability. However the alterations of these pathways, as may occur in human tumor cells with strong genomic instability, remain poorly characterized. We analyzed the loss of heterozygosity (LOH) and the presence of mutations for a series of genes implicated in DSB repair by non-homologous end-joining in five radiation-induced sarcomas devoid of both active Tp53 and Rb1. LOH was recurrently observed for 8 of the 9 studied genes (KU70, KU80, XRCC4, LIG4, Artemis, MRE11, RAD50, NBS1) but not for DNA-PKcs. No mutation was found in the remaining allele of the genes with LOH and the mRNA expression did not correlate with the allelic status. Our findings suggest that non-homologous end-joining repair pathway alteration is unlikely to be involved in the high genomic instability observed in these tumors. (author)

  7. DHX9 helicase is involved in preventing genomic instability induced by alternatively structured DNA in human cells.

    Science.gov (United States)

    Jain, Aklank; Bacolla, Albino; Del Mundo, Imee M; Zhao, Junhua; Wang, Guliang; Vasquez, Karen M

    2013-12-01

    Sequences that have the capacity to adopt alternative (i.e. non-B) DNA structures in the human genome have been implicated in stimulating genomic instability. Previously, we found that a naturally occurring intra-molecular triplex (H-DNA) caused genetic instability in mammals largely in the form of DNA double-strand breaks. Thus, it is of interest to determine the mechanism(s) involved in processing H-DNA. Recently, we demonstrated that human DHX9 helicase preferentially unwinds inter-molecular triplex DNA in vitro. Herein, we used a mutation-reporter system containing H-DNA to examine the relevance of DHX9 activity on naturally occurring H-DNA structures in human cells. We found that H-DNA significantly increased mutagenesis in small-interfering siRNA-treated, DHX9-depleted cells, affecting mostly deletions. Moreover, DHX9 associated with H-DNA in the context of supercoiled plasmids. To further investigate the role of DHX9 in the recognition/processing of H-DNA, we performed binding assays in vitro and chromatin immunoprecipitation assays in U2OS cells. DHX9 recognized H-DNA, as evidenced by its binding to the H-DNA structure and enrichment at the H-DNA region compared with a control region in human cells. These composite data implicate DHX9 in processing H-DNA structures in vivo and support its role in the overall maintenance of genomic stability at sites of alternatively structured DNA.

  8. Genomic instability in quartz dust exposed rat lungs: Is inflammation responsible?

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, C; Schins, R P F [Institut fuer Umweltmedizinische Forschung (IUF) at the Heinrich Heine University Duesseldorf (Germany); Demircigil, G Cakmak; Coskun, Erdem [Gazi University, Faculty of Pharmacy, Department of Toxicology, Ankara (Turkey); Schooten, F J van [Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Health Risk Analysis and Toxicology, University of Maastricht (Netherlands); Borm, P J A [Centre of Expertise in Life Sciences (Cel), Hogeschool Zuyd, Heerlen (Netherlands); Knaapen, A M, E-mail: catrin.albrecht@uni-duesseldorf.d

    2009-02-01

    the aluminium coated quartz intermediate effects were found. These findings were in line with the kinetics of inflammation and epithelial proliferation in the rat lungs for the different treatments. Notably, a highly significant correlation was observed between neutrophil numbers and micronucleus frequencies, indicative for a role of inflammation in eliciting genomic instability in target cells of quartz-induced carcinogenesis. Our ongoing investigations focus on the evaluation of the causality between both in relation to quartz exposure.

  9. Genomic Instability Promoted by Overexpression of Mismatch Repair Factors in Yeast: A Model for Understanding Cancer Progression.

    Science.gov (United States)

    Chakraborty, Ujani; Dinh, Timothy A; Alani, Eric

    2018-04-13

    Mismatch repair (MMR) proteins act in spellchecker roles to excise misincorporation errors that occur during DNA replication. Curiously, large-scale analyses of a variety of cancers showed that increased expression of MMR proteins often correlated with tumor aggressiveness, metastasis, and early recurrence. To better understand these observations, we used the TCGA and GENT databases to analyze MMR protein expression in cancers. We found that the MMR genes MSH2 and MSH6 are overexpressed more frequently than MSH3 , and that MSH2 and MSH6 are often co-overexpressed as a result of copy number amplifications of these genes. These observations encouraged us to test the effects of upregulating MMR protein levels in baker's yeast, where we can sensitively monitor genome instability phenotypes associated with cancer initiation and progression. Msh6 overexpression (2 to 4-fold) almost completely disrupted mechanisms that prevent recombination between divergent DNA sequences by interacting with the DNA polymerase processivity clamp PCNA and by sequestering the Sgs1 helicase. Importantly, co-overexpression of Msh2 and Msh6 (∼8-fold) conferred, in a PCNA interaction dependent manner, several genome instability phenotypes including increased mutation rate, increased sensitivity to the DNA replication inhibitor hydroxyurea and the DNA damaging agents methyl methanesulfonate and 4-nitroquinoline N-oxide, and elevated loss of heterozygosity. Msh2 and Msh6 co-overexpression also altered the cell cycle distribution of exponentially growing cells, resulting in an increased fraction of unbudded cells, consistent with a larger percentage of cells in G1. These novel observations suggested that overexpression of MSH factors affected the integrity of the DNA replication fork, causing genome instability phenotypes that could be important for promoting cancer progression. Copyright © 2018, Genetics.

  10. Molecular Mechanisms of Radiation-Induced Genomic Instability in Human Cells

    Energy Technology Data Exchange (ETDEWEB)

    Howard L. Liber; Jeffrey L. Schwartz

    2005-10-31

    There are many different model systems that have been used to study chromosome instability. What is clear from all these studies is that conclusions concerning chromosome instability depend greatly on the model system and instability endpoint that is studied. The model system for our studies was the human B-lymphoblastoid cell line TK6. TK6 was isolated from a spontaneously immortalized lymphoblast culture. Thus there was no outside genetic manipulation used to immortalize them. TK6 is a relatively stable p53-normal immortal cell line (37). It shows low gene and chromosome mutation frequencies (19;28;31). Our general approach to studying instability in TK6 cells has been to isolate individual clones and analyze gene and chromosome mutation frequencies in each. This approach maximizes the possibility of detecting low frequency events that might be selected against in mass cultures.

  11. Effects of As2O3 on DNA methylation, genomic instability, and LTR retrotransposon polymorphism in Zea mays.

    Science.gov (United States)

    Erturk, Filiz Aygun; Aydin, Murat; Sigmaz, Burcu; Taspinar, M Sinan; Arslan, Esra; Agar, Guleray; Yagci, Semra

    2015-12-01

    Arsenic is a well-known toxic substance on the living organisms. However, limited efforts have been made to study its DNA methylation, genomic instability, and long terminal repeat (LTR) retrotransposon polymorphism causing properties in different crops. In the present study, effects of As2O3 (arsenic trioxide) on LTR retrotransposon polymorphism and DNA methylation as well as DNA damage in Zea mays seedlings were investigated. The results showed that all of arsenic doses caused a decreasing genomic template stability (GTS) and an increasing Random Amplified Polymorphic DNAs (RAPDs) profile changes (DNA damage). In addition, increasing DNA methylation and LTR retrotransposon polymorphism characterized a model to explain the epigenetically changes in the gene expression were also found. The results of this experiment have clearly shown that arsenic has epigenetic effect as well as its genotoxic effect. Especially, the increasing of polymorphism of some LTR retrotransposon under arsenic stress may be a part of the defense system against the stress.

  12. Dormant origins as a built-in safeguard in eukaryotic DNA replication against genome instability and disease development.

    Science.gov (United States)

    Shima, Naoko; Pederson, Kayla D

    2017-08-01

    DNA replication is a prerequisite for cell proliferation, yet it can be increasingly challenging for a eukaryotic cell to faithfully duplicate its genome as its size and complexity expands. Dormant origins now emerge as a key component for cells to successfully accomplish such a demanding but essential task. In this perspective, we will first provide an overview of the fundamental processes eukaryotic cells have developed to regulate origin licensing and firing. With a special focus on mammalian systems, we will then highlight the role of dormant origins in preventing replication-associated genome instability and their functional interplay with proteins involved in the DNA damage repair response for tumor suppression. Lastly, deficiencies in the origin licensing machinery will be discussed in relation to their influence on stem cell maintenance and human diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. MicroRNA-34a promotes genomic instability by a broad suppression of genome maintenance mechanisms downstream of the oncogene KSHV-vGPCR.

    Science.gov (United States)

    Krause, Claudia J; Popp, Oliver; Thirunarayanan, Nanthakumar; Dittmar, Gunnar; Lipp, Martin; Müller, Gerd

    2016-03-01

    The Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded chemokine receptor vGPCR acts as an oncogene in Kaposi's sarcomagenesis. Until now, the molecular mechanisms by which the vGPCR contributes to tumor development remain incompletely understood. Here, we show that the KSHV-vGPCR contributes to tumor progression through microRNA (miR)-34a-mediated induction of genomic instability. Large-scale analyses on the DNA, gene and protein level of cell lines derived from a mouse model of vGPCR-driven tumorigenesis revealed that a vGPCR-induced upregulation of miR-34a resulted in a broad suppression of genome maintenance genes. A knockdown of either the vGPCR or miR-34a largely restored the expression of these genes and confirmed miR-34a as a downstream effector of the KSHV-vGPCR that compromises genome maintenance mechanisms. This novel, protumorigenic role of miR-34a questions the use of miR-34a mimetics in cancer therapy as they could impair genome stability.

  14. Nuclear DNA-Content in Mesenchymal Lesions in Dogs: Its Value as Marker of Malignancy and Extent of Genomic Instability

    Science.gov (United States)

    Boerkamp, Kim M.; Rutteman, Gerard R.; Kik, Marja J. L.; Kirpensteijn, Jolle; Schulze, Christoph; Grinwis, Guy C. M.

    2012-01-01

    DNA-aneuploidy may reflect the malignant nature of mesenchymal proliferations and herald gross genomic instability as a mechanistic factor in tumor genesis. DNA-ploidy and -index were determined by flow cytometry in canine inflammatory or neoplastic mesenchymal tissues and related to clinico-pathological features, biological behavior and p53 gene mutational status. Half of all sarcomas were aneuploid. Benign mesenchymal neoplasms were rarely aneuploid and inflammatory lesions not at all. The aneuploidy rate was comparable to that reported for human sarcomas with significant variation amongst subtypes. DNA-ploidy status in canines lacked a relation with histological grade of malignancy, in contrast to human sarcomas. While aneuploidy was related to the development of metastases in soft tissue sarcomas it was not in osteosarcomas. No relation amongst sarcomas was found between ploidy status and presence of P53 gene mutations. Heterogeneity of the DNA index between primary and metastatic sarcoma sites was present in half of the cases examined. Hypoploidy is more common in canine sarcomas and hyperploid cases have less deviation of the DNA index than human sarcomas. The variation in the presence and extent of aneuploidy amongst sarcoma subtypes indicates variation in genomic instability. This study strengthens the concept of interspecies variation in the evolution of gross chromosomal aberrations during cancer development. PMID:24213507

  15. Nuclear DNA-Content in Mesenchymal Lesions in Dogs: Its Value as Marker of Malignancy and Extent of Genomic Instability

    Energy Technology Data Exchange (ETDEWEB)

    Boerkamp, Kim M., E-mail: K.M.Boerkamp@uu.nl; Rutteman, Gerard R. [Department of Clinical Science of Companion Animals, Faculty of Veterinary Medicine, UU, Yalelaan 104, 3584 CM, Utrecht (Netherlands); Kik, Marja J. L. [Department of Pathobiology, Faculty of Veterinary Medicine, UU, Yalelaan 1, 3508 TD, Utrecht (Netherlands); Kirpensteijn, Jolle [Department of Clinical Science of Companion Animals, Faculty of Veterinary Medicine, UU, Yalelaan 104, 3584 CM, Utrecht (Netherlands); Schulze, Christoph; Grinwis, Guy C. M. [Department of Pathobiology, Faculty of Veterinary Medicine, UU, Yalelaan 1, 3508 TD, Utrecht (Netherlands)

    2012-12-03

    DNA-aneuploidy may reflect the malignant nature of mesenchymal proliferations and herald gross genomic instability as a mechanistic factor in tumor genesis. DNA-ploidy and -index were determined by flow cytometry in canine inflammatory or neoplastic mesenchymal tissues and related to clinico-pathological features, biological behavior and p53 gene mutational status. Half of all sarcomas were aneuploid. Benign mesenchymal neoplasms were rarely aneuploid and inflammatory lesions not at all. The aneuploidy rate was comparable to that reported for human sarcomas with significant variation amongst subtypes. DNA-ploidy status in canines lacked a relation with histological grade of malignancy, in contrast to human sarcomas. While aneuploidy was related to the development of metastases in soft tissue sarcomas it was not in osteosarcomas. No relation amongst sarcomas was found between ploidy status and presence of P53 gene mutations. Heterogeneity of the DNA index between primary and metastatic sarcoma sites was present in half of the cases examined. Hypoploidy is more common in canine sarcomas and hyperploid cases have less deviation of the DNA index than human sarcomas. The variation in the presence and extent of aneuploidy amongst sarcoma subtypes indicates variation in genomic instability. This study strengthens the concept of interspecies variation in the evolution of gross chromosomal aberrations during cancer development.

  16. Nuclear DNA-Content in Mesenchymal Lesions in Dogs: Its Value as Marker of Malignancy and Extent of Genomic Instability

    Directory of Open Access Journals (Sweden)

    Christoph Schulze

    2012-12-01

    Full Text Available DNA-aneuploidy may reflect the malignant nature of mesenchymal proliferations and herald gross genomic instability as a mechanistic factor in tumor genesis. DNA-ploidy and -index were determined by flow cytometry in canine inflammatory or neoplastic mesenchymal tissues and related to clinico-pathological features, biological behavior and p53 gene mutational status. Half of all sarcomas were aneuploid. Benign mesenchymal neoplasms were rarely aneuploid and inflammatory lesions not at all. The aneuploidy rate was comparable to that reported for human sarcomas with significant variation amongst subtypes. DNA-ploidy status in canines lacked a relation with histological grade of malignancy, in contrast to human sarcomas. While aneuploidy was related to the development of metastases in soft tissue sarcomas it was not in osteosarcomas. No relation amongst sarcomas was found between ploidy status and presence of P53 gene mutations. Heterogeneity of the DNA index between primary and metastatic sarcoma sites was present in half of the cases examined. Hypoploidy is more common in canine sarcomas and hyperploid cases have less deviation of the DNA index than human sarcomas. The variation in the presence and extent of aneuploidy amongst sarcoma subtypes indicates variation in genomic instability. This study strengthens the concept of interspecies variation in the evolution of gross chromosomal aberrations during cancer development.

  17. Nuclear DNA-Content in Mesenchymal Lesions in Dogs: Its Value as Marker of Malignancy and Extent of Genomic Instability

    International Nuclear Information System (INIS)

    Boerkamp, Kim M.; Rutteman, Gerard R.; Kik, Marja J. L.; Kirpensteijn, Jolle; Schulze, Christoph; Grinwis, Guy C. M.

    2012-01-01

    DNA-aneuploidy may reflect the malignant nature of mesenchymal proliferations and herald gross genomic instability as a mechanistic factor in tumor genesis. DNA-ploidy and -index were determined by flow cytometry in canine inflammatory or neoplastic mesenchymal tissues and related to clinico-pathological features, biological behavior and p53 gene mutational status. Half of all sarcomas were aneuploid. Benign mesenchymal neoplasms were rarely aneuploid and inflammatory lesions not at all. The aneuploidy rate was comparable to that reported for human sarcomas with significant variation amongst subtypes. DNA-ploidy status in canines lacked a relation with histological grade of malignancy, in contrast to human sarcomas. While aneuploidy was related to the development of metastases in soft tissue sarcomas it was not in osteosarcomas. No relation amongst sarcomas was found between ploidy status and presence of P53 gene mutations. Heterogeneity of the DNA index between primary and metastatic sarcoma sites was present in half of the cases examined. Hypoploidy is more common in canine sarcomas and hyperploid cases have less deviation of the DNA index than human sarcomas. The variation in the presence and extent of aneuploidy amongst sarcoma subtypes indicates variation in genomic instability. This study strengthens the concept of interspecies variation in the evolution of gross chromosomal aberrations during cancer development

  18. On the Actual Risk of Bystander Intervention

    DEFF Research Database (Denmark)

    Liebst, Lasse Suonperä; Heinskou, Marie Bruvik; Ejbye-Ernst, Peter

    2018-01-01

    Objectives: Bystander studies have rarely considered the victimization risk associated with intervention into violent, dangerous emergencies. To address this gap, we aim to identify factors that influence bystanders’ risk of being physically victimized. Methods: We observed bystander behavior fro...

  19. Bystander signaling via oxidative metabolism

    Directory of Open Access Journals (Sweden)

    Sawal HA

    2017-08-01

    Full Text Available Humaira Aziz Sawal,1 Kashif Asghar,2 Matthias Bureik,3 Nasir Jalal4 1Healthcare Biotechnology Department, Atta-ur-Rahman School of Applied Biosciences, National University of Sciences and Technology, Islamabad, 2Basic Sciences Research, Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, Pakistan; 3Health Science Platform, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China; 4Health Science Platform, Department of Molecular and Cellular Pharmacology, Tianjin University, Tianjin, China Abstract: The radiation-induced bystander effect (RIBE is the initiation of biological end points in cells (bystander cells that are not directly traversed by an incident-radiation track, but are in close proximity to cells that are receiving the radiation. RIBE has been indicted of causing DNA damage via oxidative stress, besides causing direct damage, inducing tumorigenesis, producing micronuclei, and causing apoptosis. RIBE is regulated by signaling proteins that are either endogenous or secreted by cells as a means of communication between cells, and can activate intracellular or intercellular oxidative metabolism that can further trigger signaling pathways of inflammation. Bystander signals can pass through gap junctions in attached cell lines, while the suspended cell lines transmit these signals via hormones and soluble proteins. This review provides the background information on how reactive oxygen species (ROS act as bystander signals. Although ROS have a very short half-life and have a nanometer-scale sphere of influence, the wide variety of ROS produced via various sources can exert a cumulative effect, not only in forming DNA adducts but also setting up signaling pathways of inflammation, apoptosis, cell-cycle arrest, aging, and even tumorigenesis. This review outlines the sources of the bystander effect linked to ROS in a cell, and provides methods of investigation for researchers who would like to

  20. Comprehensive characterization of genomic instability in pluripotent stem cells and their derived neuroprogenitor cell lines

    Directory of Open Access Journals (Sweden)

    Nestor Luis Lopez Corrales

    2012-12-01

    Full Text Available The genomic integrity of two human pluripotent stem cells and their derived neuroprogenitor cell lines was studied, applying a combination of high-resolution genetic methodologies. The usefulness of combining array-comparative genomic hybridization (aCGH and multiplex fluorescence in situ hybridization (M-FISH techniques should be delineated to exclude/detect a maximum of possible genomic structural aberrations. Interestingly, in parts different genomic imbalances at chromosomal and subchromosomal levels were detected in pluripotent stem cells and their derivatives. Some of the copy number variations were inherited from the original cell line, whereas other modifications were presumably acquired during the differentiation and manipulation procedures. These results underline the necessity to study both pluripotent stem cells and their differentiated progeny by as many approaches as possible in order to assess their genomic stability before using them in clinical therapies.

  1. The problem of induced genomic instability in the child organism under conditions of long-term effect of small radiation doses

    International Nuclear Information System (INIS)

    Suskov, I.I.; Kuz'mina, N.S.

    2001-01-01

    The phenomenological aspects of the genomic instability induced in the descendants of the multi-divided cells having been exposed to the radiation are examined. It is demonstrated that the regularity of the genomic instability induction do not correspond to the classical conception of the radiation genetics (hit principle and target theory). The mechanisms and the biological significance of this new genetic phenomenon in the child organism under conditions of low-intensive effect of small-dose radiation and its connection with the state of health are discussed [ru

  2. Bystander signaling via oxidative metabolism.

    Science.gov (United States)

    Sawal, Humaira Aziz; Asghar, Kashif; Bureik, Matthias; Jalal, Nasir

    2017-01-01

    The radiation-induced bystander effect (RIBE) is the initiation of biological end points in cells (bystander cells) that are not directly traversed by an incident-radiation track, but are in close proximity to cells that are receiving the radiation. RIBE has been indicted of causing DNA damage via oxidative stress, besides causing direct damage, inducing tumorigenesis, producing micronuclei, and causing apoptosis. RIBE is regulated by signaling proteins that are either endogenous or secreted by cells as a means of communication between cells, and can activate intracellular or intercellular oxidative metabolism that can further trigger signaling pathways of inflammation. Bystander signals can pass through gap junctions in attached cell lines, while the suspended cell lines transmit these signals via hormones and soluble proteins. This review provides the background information on how reactive oxygen species (ROS) act as bystander signals. Although ROS have a very short half-life and have a nanometer-scale sphere of influence, the wide variety of ROS produced via various sources can exert a cumulative effect, not only in forming DNA adducts but also setting up signaling pathways of inflammation, apoptosis, cell-cycle arrest, aging, and even tumorigenesis. This review outlines the sources of the bystander effect linked to ROS in a cell, and provides methods of investigation for researchers who would like to pursue this field of science.

  3. The role of free radicals and stress signalling in persistent genomic instability induced by long wavelength UV light

    International Nuclear Information System (INIS)

    Phillipson, R.; McMillan, T.J.

    2003-01-01

    Induction of persistent genomic instability has commonly been investigated with ionising radiation. It has been characterised as a decrease in plating efficiency, and an increase in chromosomal aberrations and mutation frequency in the progeny of cells that survive the initial irradiation. We now present data demonstrating the phenomenon following exposure to long-wavelength solar UV-A (320-400nm) radiation at environmentally relevant doses. Using the spontaneously immortalised human skin keratinocyte line, HaCaT, we observed a significant decrease in plating efficiency (77 +/- 2% of control), and increase in micronuclei (2.5 fold) and mutation frequency (2 fold), 7 days after the initial radiation insult. Modification of UV-A-induced instability by incubation with exogenous catalase implicated reactive oxygen species (ROS), in-particular hydrogen peroxide, in the production and/or maintenance of the phenomenon. Assessment of anti-oxidant enzymes revealed a significant increase in glutathione-s-transferase activity (158 +/- 4% of control) at day 7 in the irradiated cell population, which was inhibited by incubation with exogenous catalase (97 +/- 3%), providing further evidence for an ROS-mediated pathway. Furthermore, inhibition of UV-A-induced micronuclei at day 7 by the flavonoid-containing-protein inhibitor diphenyleneiodonium (DPI) indicates that the NADPH oxidase family of enzymes may be involved in this phenomenon. Measurement of superoxide production by the cytochrome c reduction assay revealed that the irradiated cell population produce 50% more superoxide than the unirradiated controls, and that incubation with DPI led to a preferential reduction in superoxide production in the UV-A treated population at day 7. Finally, NADPH oxidase activity is increased significantly over controls in UV-A-treated cells. These data demonstrate that oxidative stress, analogous to that produced by ionising radiation, induces persistent genomic instability through a

  4. Role of Ku80-dependent end-joining in delayed genomic instability in mammalian cells surviving ionizing radiation

    International Nuclear Information System (INIS)

    Suzuki, Keiji; Kodama, Seiji; Watanabe, Masami

    2010-01-01

    Ionizing radiation induces delayed destabilization of the genome in the progenies of surviving cells. This phenomenon, which is called radiation-induced genomic instability, is manifested by delayed induction of radiation effects, such as cell death, chromosome aberration, and mutation in the progeny of cells surviving radiation exposure. Previously, there was a report showing that delayed cell death was absent in Ku80-deficient Chinese hamster ovary (CHO) cells, however, the mechanism of their defect has not been determined. We found that delayed induction of DNA double strand breaks and chromosomal breaks were intact in Ku80-deficient cells surviving X-irradiation, whereas there was no sign for the production of chromosome bridges between divided daughter cells. Moreover, delayed induction of dicentric chromosomes was significantly compromised in those cells compared to the wild-type CHO cells. Reintroduction of the human Ku86 gene complimented the defective DNA repair and recovered delayed induction of dicentric chromosomes and delayed cell death, indicating that defective Ku80-dependent dicentric induction was the cause of the absence of delayed cell death. Since DNA-PKcs-defective cells showed delayed phenotypes, Ku80-dependent illegitimate rejoining is involved in delayed impairment of the integrity of the genome in radiation-survived cells.

  5. Role of Ku80-dependent end-joining in delayed genomic instability in mammalian cells surviving ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Keiji, E-mail: kzsuzuki@nagasaki-u.ac.jp [Course of Life Sciences and Radiation Research, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523 (Japan); Kodama, Seiji [Research Institute for Advanced Science and Technology, Osaka Prefecture University, 1-2 Gakuen-machi, Sakai 599-8570 (Japan); Watanabe, Masami [Kyoto University Research Reactor Institute, Kumatori-cho Sennan-gun, Osaka 590-0494 (Japan)

    2010-01-05

    Ionizing radiation induces delayed destabilization of the genome in the progenies of surviving cells. This phenomenon, which is called radiation-induced genomic instability, is manifested by delayed induction of radiation effects, such as cell death, chromosome aberration, and mutation in the progeny of cells surviving radiation exposure. Previously, there was a report showing that delayed cell death was absent in Ku80-deficient Chinese hamster ovary (CHO) cells, however, the mechanism of their defect has not been determined. We found that delayed induction of DNA double strand breaks and chromosomal breaks were intact in Ku80-deficient cells surviving X-irradiation, whereas there was no sign for the production of chromosome bridges between divided daughter cells. Moreover, delayed induction of dicentric chromosomes was significantly compromised in those cells compared to the wild-type CHO cells. Reintroduction of the human Ku86 gene complimented the defective DNA repair and recovered delayed induction of dicentric chromosomes and delayed cell death, indicating that defective Ku80-dependent dicentric induction was the cause of the absence of delayed cell death. Since DNA-PKcs-defective cells showed delayed phenotypes, Ku80-dependent illegitimate rejoining is involved in delayed impairment of the integrity of the genome in radiation-survived cells.

  6. Transgenerational developmental effects and genomic instability after X-irradiation of preimplantation embryos: Studies on two mouse strains

    International Nuclear Information System (INIS)

    Jacquet, P.; Buset, J.; Neefs, M.; Vankerkom, J.; Benotmane, M.A.; Derradji, H.; Hildebrandt, G.; Baatout, S.

    2010-01-01

    Recent results have shown that irradiation of a single cell, the zygote or 1-cell embryo of various mouse strains, could lead to congenital anomalies in the fetuses. In the Heiligenberger strain, a link between the radiation-induced congenital anomalies and the development of a genomic instability was also suggested. Moreover, further studies showed that in that strain, both congenital anomalies and genomic instability could be transmitted to the next generation. The aim of the experiments described in this paper was to investigate whether such non-targeted transgenerational effects could also be observed in two other radiosensitive mouse strains (CF1 and ICR), using lower radiation doses. Irradiation of the CF1 and ICR female zygotes with 0.2 or 0.4 Gy did not result in a decrease of their fertility after birth, when they had reached sexual maturity. Moreover, females of both strains that had been X-irradiated with 0.2 Gy exhibited higher rates of pregnancy, less resorptions and more living fetuses. Additionally, the mean weight of living fetuses in these groups had significantly increased. Exencephaly and dwarfism were observed in CF1 fetuses issued from control and X-irradiated females. In the control group of that strain, polydactyly and limb deformity were also found. The yields of abnormal fetuses did not differ significantly between the control and X-irradiated groups. Polydactyly, exencephaly and dwarfism were observed in fetuses issued from ICR control females. In addition to these anomalies, gastroschisis, curly tail and open eye were observed at low frequencies in ICR fetuses issued from X-irradiated females. Again, the frequencies of abnormal fetuses found in the different groups did not differ significantly. In both CF1 and ICR mouse strains, irradiation of female zygotes did not result in the development of a genomic instability in the next generation embryos. Overall, our results suggest that, at the moderate doses used, developmental defects

  7. Transgenerational developmental effects and genomic instability after X-irradiation of preimplantation embryos: Studies on two mouse strains

    Energy Technology Data Exchange (ETDEWEB)

    Jacquet, P., E-mail: pjacquet@sckcen.be [Molecular and Cellular Biology, Institute for Environment, Health and Safety, SCK.CEN, Boeretang 200, B-2400 Mol (Belgium); Buset, J.; Neefs, M. [Molecular and Cellular Biology, Institute for Environment, Health and Safety, SCK.CEN, Boeretang 200, B-2400 Mol (Belgium); Vankerkom, J. [Division of Environmental Research, VITO, Boeretang 200, B-2400 Mol (Belgium); Benotmane, M.A.; Derradji, H. [Molecular and Cellular Biology, Institute for Environment, Health and Safety, SCK.CEN, Boeretang 200, B-2400 Mol (Belgium); Hildebrandt, G. [Department of Radiotherapy and Radiation Oncology, University of Leipzig, Stephanstrasse 9a, D-04103 Leipzig (Germany); Department of Radiotherapy, University of Rostock, Suedring 75, D-18059 Rostock (Germany); Baatout, S. [Molecular and Cellular Biology, Institute for Environment, Health and Safety, SCK.CEN, Boeretang 200, B-2400 Mol (Belgium)

    2010-05-01

    Recent results have shown that irradiation of a single cell, the zygote or 1-cell embryo of various mouse strains, could lead to congenital anomalies in the fetuses. In the Heiligenberger strain, a link between the radiation-induced congenital anomalies and the development of a genomic instability was also suggested. Moreover, further studies showed that in that strain, both congenital anomalies and genomic instability could be transmitted to the next generation. The aim of the experiments described in this paper was to investigate whether such non-targeted transgenerational effects could also be observed in two other radiosensitive mouse strains (CF1 and ICR), using lower radiation doses. Irradiation of the CF1 and ICR female zygotes with 0.2 or 0.4 Gy did not result in a decrease of their fertility after birth, when they had reached sexual maturity. Moreover, females of both strains that had been X-irradiated with 0.2 Gy exhibited higher rates of pregnancy, less resorptions and more living fetuses. Additionally, the mean weight of living fetuses in these groups had significantly increased. Exencephaly and dwarfism were observed in CF1 fetuses issued from control and X-irradiated females. In the control group of that strain, polydactyly and limb deformity were also found. The yields of abnormal fetuses did not differ significantly between the control and X-irradiated groups. Polydactyly, exencephaly and dwarfism were observed in fetuses issued from ICR control females. In addition to these anomalies, gastroschisis, curly tail and open eye were observed at low frequencies in ICR fetuses issued from X-irradiated females. Again, the frequencies of abnormal fetuses found in the different groups did not differ significantly. In both CF1 and ICR mouse strains, irradiation of female zygotes did not result in the development of a genomic instability in the next generation embryos. Overall, our results suggest that, at the moderate doses used, developmental defects

  8. R-loops cause genomic instability in T helper lymphocytes from patients with Wiskott-Aldrich syndrome.

    Science.gov (United States)

    Sarkar, Koustav; Han, Seong-Su; Wen, Kuo-Kuang; Ochs, Hans D; Dupré, Loïc; Seidman, Michael M; Vyas, Yatin M

    2017-12-15

    Wiskott-Aldrich syndrome (WAS), X-linked thrombocytopenia (XLT), and X-linked neutropenia, which are caused by WAS mutations affecting Wiskott-Aldrich syndrome protein (WASp) expression or activity, manifest in immunodeficiency, autoimmunity, genomic instability, and lymphoid and other cancers. WASp supports filamentous actin formation in the cytoplasm and gene transcription in the nucleus. Although the genetic basis for XLT/WAS has been clarified, the relationships between mutant forms of WASp and the diverse features of these disorders remain ill-defined. We sought to define how dysfunctional gene transcription is causally linked to the degree of T H cell deficiency and genomic instability in the XLT/WAS clinical spectrum. In human T H 1- or T H 2-skewing cell culture systems, cotranscriptional R-loops (RNA/DNA duplex and displaced single-stranded DNA) and DNA double-strand breaks (DSBs) were monitored in multiple samples from patients with XLT and WAS and in normal T cells depleted of WASp. WASp deficiency provokes increased R-loops and R-loop-mediated DSBs in T H 1 cells relative to T H 2 cells. Mechanistically, chromatin occupancy of serine 2-unphosphorylated RNA polymerase II is increased, and that of topoisomerase 1, an R-loop preventing factor, is decreased at R-loop-enriched regions of IFNG and TBX21 (T H 1 genes) in T H 1 cells. These aberrations accompany increased unspliced (intron-retained) and decreased spliced mRNA of IFNG and TBX21 but not IL13 (T H 2 gene). Significantly, increased cellular load of R-loops and DSBs, which are normalized on RNaseH1-mediated suppression of ectopic R-loops, inversely correlates with disease severity scores. Transcriptional R-loop imbalance is a novel molecular defect causative in T H 1 immunodeficiency and genomic instability in patients with WAS. The study proposes that cellular R-loop load could be used as a potential biomarker for monitoring symptom severity and prognostic outcome in the XLT-WAS clinical spectrum

  9. Living with genome instability: the adaptation of phytoplasmas todiverse environments of their insect and plant hosts

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Xiaodong; Zhang, Jianhua; Ewing, Adam; Miller, Sally A.; Radek, Agnes; Shevchenko, Dimitriy; Tsukerman, Kiryl; Walunas, Theresa; Lapidus, Alla; Campbell, John W.; Hogenhout Saskia A.

    2006-02-17

    Phytoplasmas (Candidatus Phytoplasma, Class Mollicutes) cause disease in hundreds of economically important plants, and are obligately transmitted by sap-feeding insects of the order Hemiptera, mainly leafhoppers and psyllids. The 706,569-bp chromosome and four plasmids of aster yellows phytoplasma strain witches broom (AY-WB) were sequenced and compared to the onion yellows phytoplasma strain M (OY-M) genome. The phytoplasmas have small repeat-rich genomes. The repeated DNAs are organized into large clusters, potential mobile units (PMUs), which contain tra5 insertion sequences (ISs), and specialized sigma factors and membrane proteins. So far, PMUs are unique to phytoplasmas. Compared to mycoplasmas, phytoplasmas lack several recombination and DNA modification functions, and therefore phytoplasmas probably use different mechanisms of recombination, likely involving PMUs, for the creation of variability, allowing phytoplasmas to adjust to the diverse environments of plants and insects. The irregular GC skews and presence of ISs and large repeated sequences in the AY-WB and OY-M genomes are indicative of high genomic plasticity. Nevertheless, segments of {approx}250 kb, located between genes lplA and glnQ are syntenic between the two phytoplasmas, contain the majority of the metabolic genes and no ISs. AY-WB is further along in the reductive evolution process than OY-M. The AY-WB genome is {approx}154 kb smaller than the OY-M genome, primarily as a result of fewer multicopy sequences, including PMUs. Further, AY-WB lacks genes that are truncated and are part of incomplete pathways in OY-M. This is the first comparative phytoplasma genome analysis and report of the existence of PMUs in phytoplasma genomes.

  10. Crossing the LINE toward genomic instability: LINE-1 retrotransposition in cancer

    Science.gov (United States)

    Kemp, Jacqueline; Longworth, Michelle

    2015-12-01

    Retrotransposons are repetitive DNA sequences that are positioned throughout the human genome. Retrotransposons are capable of copying themselves and mobilizing new copies to novel genomic locations in a process called retrotransposition. While most retrotransposon sequences in the human genome are incomplete and incapable of mobilization, the LINE-1 retrotransposon, which comprises approximately 17% of the human genome, remains active. The disruption of cellular mechanisms that suppress retrotransposon activity is linked to the generation of aneuploidy, a potential driver of tumor development. When retrotransposons insert into a novel genomic region, they have the potential to disrupt the coding sequence of endogenous genes and alter gene expression, which can lead to deleterious consequences for the organism. Additionally, increased LINE-1 copy numbers provide more chances for recombination events to occur between retrotransposons, which can lead to chromosomal breaks and rearrangements. LINE-1 activity is increased in various cancer cell lines and in patient tissues resected from primary tumors. LINE-1 activity also correlates with increased cancer metastasis. This review aims to give a brief overview of the connections between LINE-1 retrotransposition and the loss of genome stability. We will also discuss the mechanisms that repress retrotransposition in human cells and their links to cancer.

  11. Colorectal carcinomas from Middle East: Molecular and tissue microarray analysis of genomic instability pathways

    International Nuclear Information System (INIS)

    Bavi, P.P.; Abubaker, Jehad A.; Jehan, Zeenath D.; Al-Jomah, Naif A.; Siraj, Abdul K.; Al-Harbi, Sayer R.; Atizado, Valerie L.; Uddin, S.; Al-Kuraya, Khawla S.; Abduljabbar, Alaa S.; Al-Homoud, Samar J.; Ashari, Luai H.; Al-Sanea, Nasser A.; Al-Dayel, Fouad H.

    2008-01-01

    Objective was to evaluate the overall incidence of microsatellite instability (MSI), hereditary non polyposis colorectal cancer and tumor suppressor gene (TP53) mutations in Saudi colorectal carcinomas. We studied the MSI pathway in Saudi colorectal cancers (CRC) from 179 unselected patients using 2 methods: MSI by polymerase chain reaction and immunohistochemistry detection of mutL homologs 1 and mutS homologs 2 proteins. The TP53 mutations were studied by sequencing exons 5, 6, 7 and 8. Of the 150 colorectal carcinomas analyzed for MSI, 16% of the tumors showed high level instability (MSI-H), 19.3% had low level instability (MSI-L) and the remaining 64% tumors were stable. Survival of the MSI-H group was better as compared to the MSI-L or microsatellite stable group (p=0.0217). In the MSI-H group, 48% were familial MSI tumors which could be attributable to the high incidence of consanguinity in the Saudi population. The TP53 mutations were found in 24% of the cases studied. A high production of familial MSI cases and a lower incidence of TP53 mutations are some of the hallmarks of the Saudi colorectal carcinomas which need to be explored further. (author)

  12. The induction of genomic instability in related human lymphoblasts following exposure to Cs gamma radiation vs accelerated 56Fe Ions

    International Nuclear Information System (INIS)

    Evans, H.H.; Horng, M.-F.; Ricanati, M.; Diaz-Insua, M.

    2003-01-01

    Full text: The induction of genomic instability by exposure to Cs-137 gamma radiation and Fe-56 accelerated ions was investigated by measuring the frequency and characteristics of TK6 and WTK1 unstable clones isolated 36 generations after exposure. While the two cell lines are related, TK6 is more sensitive to radiation, has normal p53 expression, and is repair deficient. Clones surviving the radiation and respective controls were analyzed for 17 characteristics including chromosomal aberrations, growth defects, alterations in response to a second radiation and mutant frequencies at two different loci. Putative unstable clones were defined as those exhibiting a significant alteration in one or more characteristics as compared to the respective control medians. Over half of the unstable WTK1 clones and over 90% of the TK6 unstable clones surviving exposure to either radiation exhibited chromosomal instability, the major aberrations consisting of chromatid breaks and dicentric chromosomes formed by end-to-end fusions. Alterations in the other measured characteristics occurred much less often than cytogenetic alterations in the TK6 unstable clones. The phenotype of the WTK1 unstable clones was more diverse and complex than in the case of TK6 unstable clones. The phenotype of the TK6 unstable clones differed in the survivors of Cs-137 vs. Fe-56. In the clones surviving Cs-137, the aberrations consisted mainly of dicentric chromosomes, while clones surviving exposure to Fe-56 exhibited both breaks and dicentrics. The uniform prevalence of chromosomal aberrations in the unstable TK6 clones vs. the relatively diverse phenotype of the unstable WTK1 clones suggests that the deficiency in DNA double-strand break repair in TK6 cells may be accompanied by a deficiency in telomere maintenance that leads to telomere fusion, dicentric chromosomes, anaphase bridges, breakage and the occurrence of chromosomal instability in the majority of clones isolated following exposure

  13. Moral Disengagement Among Bystanders to School Bullying

    DEFF Research Database (Denmark)

    Obermann, Marie-Louise

    2011-01-01

    This study examined the use of moral disengagement among children indirectly involved in bullying (bystanders). A sample of Danish adolescents (N = 660, M age 12.6 years) were divided into four groups depending on their bystander status: (a) outsiders, who did not experience bullying among...... their peers; (b) defenders, who were likely to help the victims in bullying episodes; (c) guilty bystanders, who did nothing to help bullied peers but felt guilty about it; and (d) unconcerned bystanders, who witnessed peers being bullied, without feeling responsible. Results indicated that, besides from...... active personal involvement in bullying others, being an unconcerned bystander to bullying also associates with moral disengagement. Unconcerned bystanders had significantly higher moral disengagement than guilty bystanders and defenders. Outsiders also showed significant higher disengagement than...

  14. Possible radioprotective effect of folic acid supplementation on low dose ionizing radiation-induced genomic instability in vitro.

    Science.gov (United States)

    Padula, Gisel; Ponzinibbio, María Virginia; Seoane, Analia I

    2016-08-01

    Ionizing radiation (IR) induces DNA damage through production of single and double-strand breaks and reactive oxygen species (ROS). Folic acid (FA) prevents radiation-induced DNA damage by modification of DNA synthesis and/or repair and as a radical scavenger. We hypothesized that in vitro supplementation with FA will decrease the sensitivity of cells to genetic damage induced by low dose of ionizing radiation. Annexin V, comet and micronucleus assays were performed in cultured CHO cells. After 7 days of pre-treatment with 0, 100, 200 or 300 nM FA, cultures were exposed to radiation (100 mSv). Two un-irradiated controls were executed (0 and 100 nM FA). Data were statistically analyzed with X2-test and linear regression analysis (P 0.05). We observed a significantly decreased frequency of apoptotic cells with the increasing FA concentration (P <0.05). The same trend was observed when analyzing DNA damage and chromosomal instability (P <0.05 for 300 nM). Only micronuclei frequencies showed significant differences for linear regression analysis (R2=94.04; P <0.01). Our results have demonstrated the radioprotective effect of folic acid supplementation on low dose ionizing radiation-induced genomic instability in vitro; folate status should be taken into account when studying the effect of low dose radiation in environmental or occupational exposure.

  15. Genomic instability in mice is greater in Fanconi anemia caused by deficiency of Fancd2 than Fancg.

    Science.gov (United States)

    Reliene, Ramune; Yamamoto, Mitsuko L; Rao, P Nagesh; Schiestl, Robert H

    2010-12-01

    Fanconi anemia (FA) results from mutations in the FANC genes and is characterized by bone marrow failure, birth defects, and a high incidence of cancer. FANCG is a part of the FA core complex that is responsible for monoubiquitination of FANCD2 and FANCI. The precise role of the FA pathway is not well understood, although it may be involved in homologous recombination (HR), nonhomologous end joining, and translesion synthesis (TLS). Fancd2(-/-) mice have a more severe phenotype than Fancg(-/-), and other FA core complex-deficient mice, although both Fancg and Fancd2 belong to the same FA pathway. We hypothesized that Fancd2 deficiency results in a more severe phenotype because Fancd2 also has a FA pathway-independent function in the maintenance of genomic integrity. To test this hypothesis, we determined the level of DNA damage and genomic instability in Fancd2(-/-), Fancg(-/-), and wild-type controls. Fancd2(-/-) mice displayed a higher magnitude of chromosomal breakage and micronucleus formation than the wild-type or Fancg(-/-) mice. Also, DNA strand breaks were increased in Fancd2(-/-) but not in Fancg(-/-) mice. In addition, Fancd2(-/-) mice displayed an elevated frequency of DNA deletions, resulting from HR at the endogenous p(un) locus. In contrast, in Fancg(-/-) mice, the frequency of DNA deletions was decreased. Thus, Fancd2 but not Fancg deficiency results in elevated chromosomal/DNA breakage and permanent genome rearrangements. This provides evidence that Fancd2 plays an additional role in the maintenance of genomic stability than Fancg, which might explain the higher predisposition to cancer seen in the Fancd2(-/-) mice.

  16. Combining magnetic sorting of mother cells and fluctuation tests to analyze genome instability during mitotic cell aging in Saccharomyces cerevisiae.

    Science.gov (United States)

    Patterson, Melissa N; Maxwell, Patrick H

    2014-10-16

    Saccharomyces cerevisiae has been an excellent model system for examining mechanisms and consequences of genome instability. Information gained from this yeast model is relevant to many organisms, including humans, since DNA repair and DNA damage response factors are well conserved across diverse species. However, S. cerevisiae has not yet been used to fully address whether the rate of accumulating mutations changes with increasing replicative (mitotic) age due to technical constraints. For instance, measurements of yeast replicative lifespan through micromanipulation involve very small populations of cells, which prohibit detection of rare mutations. Genetic methods to enrich for mother cells in populations by inducing death of daughter cells have been developed, but population sizes are still limited by the frequency with which random mutations that compromise the selection systems occur. The current protocol takes advantage of magnetic sorting of surface-labeled yeast mother cells to obtain large enough populations of aging mother cells to quantify rare mutations through phenotypic selections. Mutation rates, measured through fluctuation tests, and mutation frequencies are first established for young cells and used to predict the frequency of mutations in mother cells of various replicative ages. Mutation frequencies are then determined for sorted mother cells, and the age of the mother cells is determined using flow cytometry by staining with a fluorescent reagent that detects bud scars formed on their cell surfaces during cell division. Comparison of predicted mutation frequencies based on the number of cell divisions to the frequencies experimentally observed for mother cells of a given replicative age can then identify whether there are age-related changes in the rate of accumulating mutations. Variations of this basic protocol provide the means to investigate the influence of alterations in specific gene functions or specific environmental conditions on

  17. Staining Against Phospho-H2AX (gamma-H2AX) as a Marker for DNA Damage and Genomic Instability in Cancer Tissues and Cells

    NARCIS (Netherlands)

    Nagelkerke, A.P.; Span, P.N.

    2016-01-01

    Phospho-H2AX or gamma-H2AX- is a marker of DNA double-stranded breaks and can therefore be used to monitor DNA repair after, for example, irradiation. In addition, positive staining for phospho-H2AX may indicate genomic instability and telomere dysfunction in tumour cells and tissues. Here, we

  18. Combined array-comparative genomic hybridization and single-nucleotide polymorphism-loss of heterozygosity analysis reveals complex changes and multiple forms of chromosomal instability in colorectal cancers

    DEFF Research Database (Denmark)

    Gaasenbeek, Michelle; Howarth, Kimberley; Rowan, Andrew J

    2006-01-01

    Cancers with chromosomal instability (CIN) are held to be aneuploid/polyploid with multiple large-scale gains/deletions, but the processes underlying CIN are unclear and different types of CIN might exist. We investigated colorectal cancer cell lines using array-comparative genomic hybridization...

  19. Significance of genetic predisposition and genomic instability for individual sensitivity to radiation. Implications for radiation protection

    International Nuclear Information System (INIS)

    Heller, H.

    2001-01-01

    At its closed-door meeting on 20/21 January 2000 the Radiation Protection Committee dedicated much of its attention to the significance of genetic predisposition and genetic instability for individual radiation sensitivity and to the implication of this for radiation protection. The statements and contributions to the closing plenary discussion touched on many aspects of ethics, personal rights, occupational medicine and insurance issues relating to this subject, all of which extend far beyond the purely technical issues of radiation protection. The present volume contains the lecture manuscripts of the meeting as well as a summarising assessment by the Radiation Protection Committee [de

  20. Telomere-Centromere-Driven Genomic Instability Contributes to Karyotype Evolution in a Mouse Model of Melanoma

    Directory of Open Access Journals (Sweden)

    Amanda Gonçalves dos Santos Silva

    2010-01-01

    Full Text Available Aneuploidy and chromosomal instability (CIN are hallmarks of most solid tumors. These alterations may result from inaccurate chromosomal segregation during mitosis, which can occur through several mechanisms including defective telomere metabolism, centrosome amplification, dysfunctional centromeres, and/or defective spindle checkpoint control. In this work, we used an in vitro murine melanoma model that uses a cellular adhesion blockade as a transforming factor to characterize telomeric and centromeric alterations that accompany melanocyte transformation. To study the timing of the occurrence of telomere shortening in this transformation model, we analyzed the profile of telomere length by quantitative fluorescent in situ hybridization and found that telomere length significantly decreased as additional rounds of cell adhesion blockages were performed. Together with it, an increase in telomere-free ends and complex karyotypic aberrations were also found, which include Robertsonian fusions in 100% of metaphases of the metastatic melanoma cells. These findings are in agreement with the idea that telomere length abnormalities seem to be one of the earliest genetic alterations acquired in the multistep process of malignant transformation and that telomere abnormalities result in telomere aggregation, breakage-bridge-fusion cycles, and CIN. Another remarkable feature of this model is the abundance of centromeric instability manifested as centromere fragments and centromeric fusions. Taken together, our results illustrate for this melanoma model CIN with a structural signature of centromere breakage and telomeric loss.

  1. Phosphate steering by Flap Endonuclease 1 promotes 5′-flap specificity and incision to prevent genome instability

    KAUST Repository

    Tsutakawa, Susan E.

    2017-06-27

    DNA replication and repair enzyme Flap Endonuclease 1 (FEN1) is vital for genome integrity, and FEN1 mutations arise in multiple cancers. FEN1 precisely cleaves single-stranded (ss) 5\\'-flaps one nucleotide into duplex (ds) DNA. Yet, how FEN1 selects for but does not incise the ss 5\\'-flap was enigmatic. Here we combine crystallographic, biochemical and genetic analyses to show that two dsDNA binding sites set the 5\\'polarity and to reveal unexpected control of the DNA phosphodiester backbone by electrostatic interactions. Via phosphate steering\\', basic residues energetically steer an inverted ss 5\\'-flap through a gateway over FEN1\\'s active site and shift dsDNA for catalysis. Mutations of these residues cause an 18,000-fold reduction in catalytic rate in vitro and large-scale trinucleotide (GAA) repeat expansions in vivo, implying failed phosphate-steering promotes an unanticipated lagging-strand template-switch mechanism during replication. Thus, phosphate steering is an unappreciated FEN1 function that enforces 5\\'-flap specificity and catalysis, preventing genomic instability.

  2. Mechanisms of the Bystander Effect

    International Nuclear Information System (INIS)

    Hall, Eric J.

    2008-01-01

    Generations of students in radiation biology have been taught that heritable biological damage requires direct damage to DNA. We now know that this is not true. The Bystander Effect is the name given to the phenomenon whereby biological effects are observed in cells that are not themselves traversed by a charged particle, but are in close proximity to cells that are. Several research groups have convincingly demonstrated a bystander effect for alpha particle, which are heavy and high LET, because charged particles can be focused into a tiny beam that can be directed onto individual cells. The biological effects seen in adjacent non-hit cells clearly represents a bystander effect. It is not so easy to demonstrate a similar effect for x-rays or for the electrons set in motion by the absorption of x-rays. In this project we used two types of cell that could be recognized one from the other. One cell type was fed radioactive tritiated thymidine, which is incorporated into the DNA, . The tritium emits electrons which have a very short range so that they do not even get out of the cell. These cells were then mixed with a different type of cell which are routinely used to assess mutations. The mixed cells formed a cluster, where the two types of cells were in close contact, and left for some hours. Subsequently, the two types of cells were separated and studied. A substantial fraction of the cells that had incorporated the tritiated thymidine were killed by the radiation. The interesting finding is that the cells that had not incorporated tritiated thymidine, but had been in close contact with cells that had, exhibited a significant incidence of mutations. These experiments clearly demonstrated a bystander effect for low LET electrons. In further experiments, it was possible to show that the bystander effect was greatest when the two cell types were in gap junction communication.

  3. Telomerase as a potential anticancer target: growth inhibition and genomic instability.

    Science.gov (United States)

    Faraoni, Isabella; Graziani, Grazia

    2000-02-01

    Stabilization of telomere length in chromosomes by an RNA-dependent DNA polymerase (telomerase) appears to be responsible for the replicative immortality of cancer cells. These findings provide the rational basis for generating experimental models to develop anti-telomerase drugs. However, there is conflicting evidence in the literature about the outcome of telomerase inhibition. While tumor cytostatic and cytotoxic effects associated with telomerase inhibition have been described, absence of telomerase has been associated with genetic instability and tumor development. Therefore, a therapeutic strategy based on telomerase inhibition will likely have to cope with problems related to innate or acquired mechanisms of drug resistance and possibly to therapy-related tumors. Copyright 2000 Harcourt Publishers Ltd.

  4. ATM Deficiency Generating Genomic Instability Sensitizes Pancreatic Ductal Adenocarcinoma Cells to Therapy-Induced DNA Damage.

    Science.gov (United States)

    Perkhofer, Lukas; Schmitt, Anna; Romero Carrasco, Maria Carolina; Ihle, Michaela; Hampp, Stephanie; Ruess, Dietrich Alexander; Hessmann, Elisabeth; Russell, Ronan; Lechel, André; Azoitei, Ninel; Lin, Qiong; Liebau, Stefan; Hohwieler, Meike; Bohnenberger, Hanibal; Lesina, Marina; Algül, Hana; Gieldon, Laura; Schröck, Evelin; Gaedcke, Jochen; Wagner, Martin; Wiesmüller, Lisa; Sipos, Bence; Seufferlein, Thomas; Reinhardt, Hans Christian; Frappart, Pierre-Olivier; Kleger, Alexander

    2017-10-15

    Pancreatic ductal adenocarcinomas (PDAC) harbor recurrent functional mutations of the master DNA damage response kinase ATM, which has been shown to accelerate tumorigenesis and epithelial-mesenchymal transition. To study how ATM deficiency affects genome integrity in this setting, we evaluated the molecular and functional effects of conditional Atm deletion in a mouse model of PDAC. ATM deficiency was associated with increased mitotic defects, recurrent genomic rearrangements, and deregulated DNA integrity checkpoints, reminiscent of human PDAC. We hypothesized that altered genome integrity might allow synthetic lethality-based options for targeted therapeutic intervention. Supporting this possibility, we found that the PARP inhibitor olaparib or ATR inhibitors reduced the viability of PDAC cells in vitro and in vivo associated with a genotype-selective increase in apoptosis. Overall, our results offered a preclinical mechanistic rationale for the use of PARP and ATR inhibitors to improve treatment of ATM-mutant PDAC. Cancer Res; 77(20); 5576-90. ©2017 AACR . ©2017 American Association for Cancer Research.

  5. CENPA overexpression promotes genome instability in pRb-depleted human cells

    Directory of Open Access Journals (Sweden)

    Lentini Laura

    2009-12-01

    Full Text Available Abstract Background Aneuploidy is a hallmark of most human cancers that arises as a consequence of chromosomal instability and it is frequently associated with centrosome amplification. Functional inactivation of the Retinoblastoma protein (pRb has been indicated as a cause promoting chromosomal instability as well centrosome amplification. However, the underlying molecular mechanism still remains to be clarified. Results Here we show that pRb depletion both in wild type and p53 knockout HCT116 cells was associated with the presence of multipolar spindles, anaphase bridges, lagging chromosomes and micronuclei harbouring whole chromosomes. In addition aneuploidy caused by pRb acute loss was not affected by p53 loss. Quantitative real-time RT-PCR showed that pRB depletion altered expression of genes involved in centrosome duplication, kinetochore assembly and in the Spindle Assembly Checkpoint (SAC. However, despite MAD2 up-regulation pRb-depleted cells seemed to have a functional SAC since they arrested in mitosis after treatments with mitotic poisons. Moreover pRb-depleted HCT116 cells showed BRCA1 overexpression that seemed responsible for MAD2 up-regulation. Post-transcriptional silencing of CENPA by RNA interference, resulting in CENP-A protein levels similar to those present in control cells greatly reduced aneuploid cell numbers in pRb-depleted cells. Conclusion Altogether our findings indicate a novel aspect of pRb acute loss that promotes aneuploidy mainly by inducing CENPA overexpression that in turn might induce micronuclei by affecting the correct attachment of spindle microtubules to kinetochores.

  6. The Adaptive Response in p53 Cancer Prone Mice: Loss of heterozygosity and Genomic Instability

    International Nuclear Information System (INIS)

    Lavoie Jose; Dolling Jo-Anna; Mitchel Ron E J; Boreham Douglas R

    2004-01-01

    The Trp53 gene is clearly associated with increased cancer risk. This, coupled with the broad understanding of its mode of action at the molecular level, makes this gene a good candidate for investigating the relationship between genetic risk factors and spontaneous cancer occurring in a mouse model exposed to low dose radiation. We have shown that adaptive response to chronic low dose radiation could increase cancer latency, as well as overall lifespan. To better understand the molecular processes that influence cellular risk, modern tools in molecular biology were used to evaluate the loss of heterozigozity (LOH) at the Trp53 locus, and chromosomal instability in the cells from mice exposed to chronic low dose radiation. Female mice carrying a single defective copy of the Trp53 gene were irradiated with doses of gamma-radiation delivered at a low dose rate of about 0.7 mGy/hr. Groups of mice (5 irradiated and 5 unexposed) were exposed to 0.33 mGy per day for 15, 30, 45, 60, 67 and 75 weeks equaling total body doses of 2.4, 4.7, 7.2, 9.7, 10.9 and 12.1 cGy, respectively. The presence of a single defective copy of the Trp53 gene increases cancer risk in these mice. However, in vivo exposure to low dose radiation increased cancer latency. We hypothesized that: (1) These mice might have spontaneous chromosome instability, and (2) that this low dose adaptive exposure would reduce the chromosomal instability. This instability was investigated using spectral karyotyping (SKY). Bone marrow cells from 5 irradiated mice (doses of 10.9 and 12.1 cGy) and 5 control mice were collected for metaphase harvest. Briefly, the cells were incubated at 37 C for 4 hours in RPMI containing 25% heat-inactivated FBS and 0.1 mg/ml colcemid, and then given a hypotonic treatment of 0.075M KCl for 20 minutes at 37 C. An average of 100 metaphases per mouse were karyotyped. The Trp53 heterozygous mice do not show apparent structural chromosome instability. From both unexposed and irradiated

  7. Bystander effect: Biological endpoints and microarray analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhry, M. Ahmad [Department of Medical Laboratory and Radiation Sciences, College of Nursing and Health Sciences, University of Vermont, 302 Rowell Building, Burlington, VT 05405 (United States) and DNA Microarray Facility, University of Vermont, Burlington, VT 05405 (United States)]. E-mail: mchaudhr@uvm.edu

    2006-05-11

    In cell populations exposed to ionizing radiation, the biological effects occur in a much larger proportion of cells than are estimated to be traversed by radiation. It has been suggested that irradiated cells are capable of providing signals to the neighboring unirradiated cells resulting in damage to these cells. This phenomenon is termed the bystander effect. The bystander effect induces persistent, long-term, transmissible changes that result in delayed death and neoplastic transformation. Because the bystander effect is relevant to carcinogenesis, it could have significant implications for risk estimation for radiation exposure. The nature of the bystander effect signal and how it impacts the unirradiated cells remains to be elucidated. Examination of the changes in gene expression could provide clues to understanding the bystander effect and could define the signaling pathways involved in sustaining damage to these cells. The microarray technology serves as a tool to gain insight into the molecular pathways leading to bystander effect. Using medium from irradiated normal human diploid lung fibroblasts as a model system we examined gene expression alterations in bystander cells. The microarray data revealed that the radiation-induced gene expression profile in irradiated cells is different from unirradiated bystander cells suggesting that the pathways leading to biological effects in the bystander cells are different from the directly irradiated cells. The genes known to be responsive to ionizing radiation were observed in irradiated cells. Several genes were upregulated in cells receiving media from irradiated cells. Surprisingly no genes were found to be downregulated in these cells. A number of genes belonging to extracellular signaling, growth factors and several receptors were identified in bystander cells. Interestingly 15 genes involved in the cell communication processes were found to be upregulated. The induction of receptors and the cell

  8. Bystander effect: Biological endpoints and microarray analysis

    International Nuclear Information System (INIS)

    Chaudhry, M. Ahmad

    2006-01-01

    In cell populations exposed to ionizing radiation, the biological effects occur in a much larger proportion of cells than are estimated to be traversed by radiation. It has been suggested that irradiated cells are capable of providing signals to the neighboring unirradiated cells resulting in damage to these cells. This phenomenon is termed the bystander effect. The bystander effect induces persistent, long-term, transmissible changes that result in delayed death and neoplastic transformation. Because the bystander effect is relevant to carcinogenesis, it could have significant implications for risk estimation for radiation exposure. The nature of the bystander effect signal and how it impacts the unirradiated cells remains to be elucidated. Examination of the changes in gene expression could provide clues to understanding the bystander effect and could define the signaling pathways involved in sustaining damage to these cells. The microarray technology serves as a tool to gain insight into the molecular pathways leading to bystander effect. Using medium from irradiated normal human diploid lung fibroblasts as a model system we examined gene expression alterations in bystander cells. The microarray data revealed that the radiation-induced gene expression profile in irradiated cells is different from unirradiated bystander cells suggesting that the pathways leading to biological effects in the bystander cells are different from the directly irradiated cells. The genes known to be responsive to ionizing radiation were observed in irradiated cells. Several genes were upregulated in cells receiving media from irradiated cells. Surprisingly no genes were found to be downregulated in these cells. A number of genes belonging to extracellular signaling, growth factors and several receptors were identified in bystander cells. Interestingly 15 genes involved in the cell communication processes were found to be upregulated. The induction of receptors and the cell

  9. Merkel cell polyomavirus small T antigen induces genome instability by E3 ubiquitin ligase targeting.

    Science.gov (United States)

    Kwun, H J; Wendzicki, J A; Shuda, Y; Moore, P S; Chang, Y

    2017-12-07

    The formation of a bipolar mitotic spindle is an essential process for the equal segregation of duplicated DNA into two daughter cells during mitosis. As a result of deregulated cellular signaling pathways, cancer cells often suffer a loss of genome integrity that might etiologically contribute to carcinogenesis. Merkel cell polyomavirus (MCV) small T (sT) oncoprotein induces centrosome overduplication, aneuploidy, chromosome breakage and the formation of micronuclei by targeting cellular ligases through a sT domain that also inhibits MCV large T oncoprotein turnover. These results provide important insight as to how centrosome number and chromosomal stability can be affected by the E3 ligase targeting capacity of viral oncoproteins such as MCV sT, which may contribute to Merkel cell carcinogenesis.

  10. DNA end resection by CtIP and exonuclease 1 prevents genomic instability

    DEFF Research Database (Denmark)

    Eid, Wassim; Steger, Martin; El-Shemerly, Mahmoud

    2010-01-01

    End resection of DNA-which is essential for the repair of DNA double-strand breaks (DSBs) by homologous recombination-relies first on the partnership between MRE11-RAD50-NBS1 (MRN) and CtIP, followed by a processive step involving helicases and exonucleases such as exonuclease 1 (EXO1). In this s......End resection of DNA-which is essential for the repair of DNA double-strand breaks (DSBs) by homologous recombination-relies first on the partnership between MRE11-RAD50-NBS1 (MRN) and CtIP, followed by a processive step involving helicases and exonucleases such as exonuclease 1 (EXO1...... of DNA-PK-dependent radial chromosome formation. Thus, our study identifies new functions of CtIP and EXO1 in DNA end resection and provides new information on the regulation of DSB repair pathways, which is a key factor in the maintenance of genome integrity....

  11. DNA Mismatch Repair Deficiency Promotes Genomic Instability in a Subset of Papillary Thyroid Cancers.

    Science.gov (United States)

    Javid, Mahsa; Sasanakietkul, Thanyawat; Nicolson, Norman G; Gibson, Courtney E; Callender, Glenda G; Korah, Reju; Carling, Tobias

    2018-02-01

    Efficient DNA damage repair by MutL-homolog DNA mismatch repair (MMR) enzymes, MLH1, MLH3, PMS1 and PMS2, are required to maintain thyrocyte genomic integrity. We hypothesized that persistent oxidative stress and consequent transcriptional dysregulation observed in thyroid follicles will lead to MMR deficiency and potentiate papillary thyroid tumorigenesis. MMR gene expression was analyzed by targeted microarray in 18 papillary thyroid cancer (PTC), 9 paracarcinoma normal thyroid (PCNT) and 10 normal thyroid (NT) samples. The findings were validated by qRT-PCR, and in follicular thyroid cancers (FTC) and follicular thyroid adenomas (FTA) for comparison. FOXO transcription factor expression was also analyzed. Protein expression was assessed by immunohistochemistry. Genomic integrity was evaluated by whole-exome sequencing-derived read-depth analysis and Mann-Whitney U test. Clinical correlations were assessed using Fisher's exact and t tests. Microarray and qRT-PCR revealed reduced expression of all four MMR genes in PTC compared with PCNT and of PMS2 compared with NT. FTC and FTA showed upregulation in MLH1, MLH3 and PMS2. PMS2 protein expression correlated with the mRNA expression pattern. FOXO1 showed lower expression in PMS2-deficient PTCs (log2-fold change -1.72 vs. -0.55, U = 11, p clinical characteristics. MMR deficiency, potentially promoted by FOXO1 suppression, may explain the etiology for PTC development in some patients. FTC and FTA retain MMR activity and are likely caused by a different tumorigenic pathway.

  12. Bystander effect induced by radiotherapeutic doses in breast carcinoma cell line

    International Nuclear Information System (INIS)

    Zubiria, M.G.; Martinez, M.; Dodat, D.; Sanchez, G.; Casas, O.; Guerci, A.

    2008-01-01

    Full text: Bystander effect (BSE) refers to observed effects in cells that have not been directly crossed by radiation and which are near the radiated cells. It is suggested that different communication and signaling cellular pathways, such as gap junctions and the release of diverse clastogenics factors (reactive oxygen species and cytokines), take place in this phenomenon. Delayed Genomic Instability (GI) could be explained by means of BSE and it could be showed by the decrease of cloning efficiency, the increase of apoptosis, point mutations, and micronuclei frequency. The relevance of this phenomenon is discussed in the carcinogenic process. Besides, BSE is also important because of its impact on the present paradigm of the ionizing effect of radiation, essentially based on the Theory of the Target. The importance of this research in radiotherapy could be the optimization of the therapeutic effects of radiation. In the present study was evaluated the BSE in breast carcinoma cell line MCF-7 by the application of both techniques: Comet Assay (alkaline version) and Clonogenic Assay. Conclusions: ROS involvement in BSE was corroborated by Comet Assay in this cell line; ICM treatment decreased cloning efficiency, checked by Clonogenic Assay. This results are very important for the reconsideration of the current paradigm of Target Theory and its application in radiobiology. (author)

  13. Bystander effects in unicellular organisms

    International Nuclear Information System (INIS)

    DeVeaux, Linda C.; Durtschi, Lynn S.; Case, Jonathan G.; Wells, Douglas P.

    2006-01-01

    Radiation-induced bystander effects have been seen in mammalian cells from diverse origins. These effects can be transmitted through the medium to cells not present at the time of irradiation. We have developed an assay for detecting bystander effects in the unicellular eukaryote, the fission yeast Schizosaccharomyces pombe. This assay allows maximal exposure of unirradiated cells to cells that have received electron beam irradiation. S. pombe cells were irradiated with 16-18 MeV electrons from a pulsed electron LINAC. When survival of the irradiated cells decreased to approximately 50%, forward-mutation to 2-deoxy-D-glucose resistance increased in the unirradiated bystander cells. Further increase in dose had no additional effect on this increase. In order to detect this response, it was necessary for the irradiated cell/unirradiated cell ratio to be high. Other cellular stresses, such as heat treatment, UV irradiation, and bleomycin exposure, also caused a detectable response in untreated cells grown with the treated cells. We discuss evolutionary implications of these results

  14. Bystander effects in unicellular organisms

    Energy Technology Data Exchange (ETDEWEB)

    DeVeaux, Linda C. [Idaho Accelerator Center, Campus Box 8263, Idaho State University, Pocatello, ID 83209 (United States) and Department of Biological Sciences, Campus Box 8007, Idaho State University, Pocatello, ID 83209 (United States)]. E-mail: develind@isu.edu; Durtschi, Lynn S. [Department of Biological Sciences, Campus Box 8007, Idaho State University, Pocatello, ID 83209 (United States); Case, Jonathan G. [Department of Physics, Campus Box 8106, Idaho State University, Pocatello, ID 83209 (United States); Wells, Douglas P. [Department of Physics, Campus Box 8106, Idaho State University, Pocatello, ID 83209 (United States)

    2006-05-11

    Radiation-induced bystander effects have been seen in mammalian cells from diverse origins. These effects can be transmitted through the medium to cells not present at the time of irradiation. We have developed an assay for detecting bystander effects in the unicellular eukaryote, the fission yeast Schizosaccharomyces pombe. This assay allows maximal exposure of unirradiated cells to cells that have received electron beam irradiation. S. pombe cells were irradiated with 16-18 MeV electrons from a pulsed electron LINAC. When survival of the irradiated cells decreased to approximately 50%, forward-mutation to 2-deoxy-D-glucose resistance increased in the unirradiated bystander cells. Further increase in dose had no additional effect on this increase. In order to detect this response, it was necessary for the irradiated cell/unirradiated cell ratio to be high. Other cellular stresses, such as heat treatment, UV irradiation, and bleomycin exposure, also caused a detectable response in untreated cells grown with the treated cells. We discuss evolutionary implications of these results.

  15. Bystander effects in unicellular organisms.

    Science.gov (United States)

    DeVeaux, Linda C; Durtschi, Lynn S; Case, Jonathan G; Wells, Douglas P

    2006-05-11

    Radiation-induced bystander effects have been seen in mammalian cells from diverse origins. These effects can be transmitted through the medium to cells not present at the time of irradiation. We have developed an assay for detecting bystander effects in the unicellular eukaryote, the fission yeast Schizosaccharomyces pombe. This assay allows maximal exposure of unirradiated cells to cells that have received electron beam irradiation. S. pombe cells were irradiated with 16-18 MeV electrons from a pulsed electron LINAC. When survival of the irradiated cells decreased to approximately 50%, forward-mutation to 2-deoxy-d-glucose resistance increased in the unirradiated bystander cells. Further increase in dose had no additional effect on this increase. In order to detect this response, it was necessary for the irradiated cell/unirradiated cell ratio to be high. Other cellular stresses, such as heat treatment, UV irradiation, and bleomycin exposure, also caused a detectable response in untreated cells grown with the treated cells. We discuss evolutionary implications of these results.

  16. dAdd1 and dXNP prevent genome instability by maintaining HP1a localization at Drosophila telomeres.

    Science.gov (United States)

    Chavez, Joselyn; Murillo-Maldonado, Juan Manuel; Bahena, Vanessa; Cruz, Ana Karina; Castañeda-Sortibrán, América; Rodriguez-Arnaiz, Rosario; Zurita, Mario; Valadez-Graham, Viviana

    2017-12-01

    Telomeres are important contributors to genome stability, as they prevent linear chromosome end degradation and contribute to the avoidance of telomeric fusions. An important component of the telomeres is the heterochromatin protein 1a (HP1a). Mutations in Su(var)205, the gene encoding HP1a in Drosophila, result in telomeric fusions, retrotransposon regulation loss and larger telomeres, leading to chromosome instability. Previously, it was found that several proteins physically interact with HP1a, including dXNP and dAdd1 (orthologues to the mammalian ATRX gene). In this study, we found that mutations in the genes encoding the dXNP and dAdd1 proteins affect chromosome stability, causing chromosomal aberrations, including telomeric defects, similar to those observed in Su(var)205 mutants. In somatic cells, we observed that dXNP and dAdd1 participate in the silencing of the telomeric HTT array of retrotransposons, preventing anomalous retrotransposon transcription and integration. Furthermore, the lack of dAdd1 results in the loss of HP1a from the telomeric regions without affecting other chromosomal HP1a binding sites; mutations in dxnp also affected HP1a localization but not at all telomeres, suggesting a specialized role for dAdd1 and dXNP proteins in locating HP1a at the tips of the chromosomes. These results place dAdd1 as an essential regulator of HP1a localization and function in the telomere heterochromatic domain.

  17. The influence of elevated endogenous free radical production on apoptosis and genomic instability in transgenic growth hormone mice

    International Nuclear Information System (INIS)

    Lemon, J.A.; Rollo, D.; Boreham, D.R.

    2003-01-01

    Full text: Previous studies have shown transgenic growth hormone mice (TGM) have significantly elevated levels of endogenous reactive oxygen species (ROS) and lipid peroxidation, shortened lifespan (approximately 50% of normal siblings), greatly enhanced learning in youth, and accelerated aging with a rapid age-related loss of cognitive abilities. A complex oral antioxidant supplement was found to completely abolish the cognitive decline and significantly extend longevity in TGM. We have determined in a recently completed experiment studying radiation-induced apoptosis that the antioxidant supplement significantly reduces the elevated level of apoptosis seen in untreated old TGM compared to age-matched controls. It was also determined that older normal mice treated with the supplement also show a reduction in apoptosis. We are conducting experiments using spectral karyotyping to examine genomic instability in TGM and their normal siblings, that indicate, given their elevated ROS, TGM show an increase in chromosome aberrations compared to normal controls. Based on our previous experiments we speculate that TGM treated with the antioxidant supplement are expected to show a reduction in ROS induced chromosome aberrations

  18. ATM-deficiency increases genomic instability and metastatic potential in a mouse model of pancreatic cancer.

    Science.gov (United States)

    Drosos, Yiannis; Escobar, David; Chiang, Ming-Yi; Roys, Kathryn; Valentine, Virginia; Valentine, Marc B; Rehg, Jerold E; Sahai, Vaibhav; Begley, Lesa A; Ye, Jianming; Paul, Leena; McKinnon, Peter J; Sosa-Pineda, Beatriz

    2017-09-11

    Germline mutations in ATM (encoding the DNA-damage signaling kinase, ataxia-telangiectasia-mutated) increase Familial Pancreatic Cancer (FPC) susceptibility, and ATM somatic mutations have been identified in resected human pancreatic tumors. Here we investigated how Atm contributes to pancreatic cancer by deleting this gene in a murine model of the disease expressing oncogenic Kras (Kras G12D ). We show that partial or total ATM deficiency cooperates with Kras G12D to promote highly metastatic pancreatic cancer. We also reveal that ATM is activated in pancreatic precancerous lesions in the context of DNA damage and cell proliferation, and demonstrate that ATM deficiency leads to persistent DNA damage in both precancerous lesions and primary tumors. Using low passage cultures from primary tumors and liver metastases we show that ATM loss accelerates Kras-induced carcinogenesis without conferring a specific phenotype to pancreatic tumors or changing the status of the tumor suppressors p53, p16 Ink4a and p19 Arf . However, ATM deficiency markedly increases the proportion of chromosomal alterations in pancreatic primary tumors and liver metastases. More importantly, ATM deficiency also renders murine pancreatic tumors highly sensitive to radiation. These and other findings in our study conclusively establish that ATM activity poses a major barrier to oncogenic transformation in the pancreas via maintaining genomic stability.

  19. Omics Approaches for Identifying Physiological Adaptations to Genome Instability in Aging.

    Science.gov (United States)

    Edifizi, Diletta; Schumacher, Björn

    2017-11-04

    DNA damage causally contributes to aging and age-related diseases. The declining functioning of tissues and organs during aging can lead to the increased risk of succumbing to aging-associated diseases. Congenital syndromes that are caused by heritable mutations in DNA repair pathways lead to cancer susceptibility and accelerated aging, thus underlining the importance of genome maintenance for withstanding aging. High-throughput mass-spectrometry-based approaches have recently contributed to identifying signalling response networks and gaining a more comprehensive understanding of the physiological adaptations occurring upon unrepaired DNA damage. The insulin-like signalling pathway has been implicated in a DNA damage response (DDR) network that includes epidermal growth factor (EGF)-, AMP-activated protein kinases (AMPK)- and the target of rapamycin (TOR)-like signalling pathways, which are known regulators of growth, metabolism, and stress responses. The same pathways, together with the autophagy-mediated proteostatic response and the decline in energy metabolism have also been found to be similarly regulated during natural aging, suggesting striking parallels in the physiological adaptation upon persistent DNA damage due to DNA repair defects and long-term low-level DNA damage accumulation occurring during natural aging. These insights will be an important starting point to study the interplay between signalling networks involved in progeroid syndromes that are caused by DNA repair deficiencies and to gain new understanding of the consequences of DNA damage in the aging process.

  20. Omics Approaches for Identifying Physiological Adaptations to Genome Instability in Aging

    Directory of Open Access Journals (Sweden)

    Diletta Edifizi

    2017-11-01

    Full Text Available DNA damage causally contributes to aging and age-related diseases. The declining functioning of tissues and organs during aging can lead to the increased risk of succumbing to aging-associated diseases. Congenital syndromes that are caused by heritable mutations in DNA repair pathways lead to cancer susceptibility and accelerated aging, thus underlining the importance of genome maintenance for withstanding aging. High-throughput mass-spectrometry-based approaches have recently contributed to identifying signalling response networks and gaining a more comprehensive understanding of the physiological adaptations occurring upon unrepaired DNA damage. The insulin-like signalling pathway has been implicated in a DNA damage response (DDR network that includes epidermal growth factor (EGF-, AMP-activated protein kinases (AMPK- and the target of rapamycin (TOR-like signalling pathways, which are known regulators of growth, metabolism, and stress responses. The same pathways, together with the autophagy-mediated proteostatic response and the decline in energy metabolism have also been found to be similarly regulated during natural aging, suggesting striking parallels in the physiological adaptation upon persistent DNA damage due to DNA repair defects and long-term low-level DNA damage accumulation occurring during natural aging. These insights will be an important starting point to study the interplay between signalling networks involved in progeroid syndromes that are caused by DNA repair deficiencies and to gain new understanding of the consequences of DNA damage in the aging process.

  1. Yeast Sub1 and human PC4 are G-quadruplex binding proteins that suppress genome instability at co-transcriptionally formed G4 DNA.

    Science.gov (United States)

    Lopez, Christopher R; Singh, Shivani; Hambarde, Shashank; Griffin, Wezley C; Gao, Jun; Chib, Shubeena; Yu, Yang; Ira, Grzegorz; Raney, Kevin D; Kim, Nayun

    2017-06-02

    G-quadruplex or G4 DNA is a non-B secondary DNA structure consisting of a stacked array of guanine-quartets that can disrupt critical cellular functions such as replication and transcription. When sequences that can adopt Non-B structures including G4 DNA are located within actively transcribed genes, the reshaping of DNA topology necessary for transcription process stimulates secondary structure-formation thereby amplifying the potential for genome instability. Using a reporter assay designed to study G4-induced recombination in the context of an actively transcribed locus in Saccharomyces cerevisiae, we tested whether co-transcriptional activator Sub1, recently identified as a G4-binding factor, contributes to genome maintenance at G4-forming sequences. Our data indicate that, upon Sub1-disruption, genome instability linked to co-transcriptionally formed G4 DNA in Top1-deficient cells is significantly augmented and that its highly conserved DNA binding domain or the human homolog PC4 is sufficient to suppress G4-associated genome instability. We also show that Sub1 interacts specifically with co-transcriptionally formed G4 DNA in vivo and that yeast cells become highly sensitivity to G4-stabilizing chemical ligands by the loss of Sub1. Finally, we demonstrate the physical and genetic interaction of Sub1 with the G4-resolving helicase Pif1, suggesting a possible mechanism by which Sub1 suppresses instability at G4 DNA. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  2. Enhanced micronucleus formation in the descendants of {gamma}-ray-irradiated tobacco cells: Evidence for radiation-induced genomic instability in plant cells

    Energy Technology Data Exchange (ETDEWEB)

    Yokota, Yuichiro, E-mail: yokota.yuichiro@jaea.go.jp [Life Science and Biotechnology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Funayama, Tomoo; Hase, Yoshihiro [Life Science and Biotechnology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Hamada, Nobuyuki [Radiation Safety Research Center, Nuclear Technology Research Laboratory, Central Research Institute of Electric Power Industry, 2-11-1 Iwado-kita, Komae, Tokyo 201-8511 (Japan); Kobayashi, Yasuhiko; Tanaka, Atsushi; Narumi, Issay [Life Science and Biotechnology Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan)

    2010-09-10

    Ionizing radiation-induced genomic instability has been documented in various end points such as chromosomal aberrations and mutations, which arises in the descendants of irradiated mammalian or yeast cells many generations after the initial insult. This study aimed at addressing radiation-induced genomic instability in higher plant tobacco cells. We thus investigated micronucleus (MN) formation and cell proliferation in tobacco cells irradiated with {gamma}-rays and their descendants. In {gamma}-irradiated cells, cell cycle was arrested at G{sub 2}/M phase at around 24 h post-irradiation but released afterward. In contrast, MN frequency peaked at 48 h post-irradiation. Almost half of 40 Gy-irradiated cells had MN at 48 h post-irradiation, but proliferated as actively as sham-irradiated cells up to 120 h post-irradiation. Moreover, the descendants that have undergone at least 22 generations after irradiation still showed a two-fold MN frequency compared to sham-irradiated cells. This is the direct evidence for radiation-induced genomic instability in tobacco cells.

  3. K-ras2 Activation and Genome Instability Increase Proliferation and Size of FAP Adenomas

    Directory of Open Access Journals (Sweden)

    Anna Rapallo

    1999-01-01

    Full Text Available The possible role of K‐ras2 mutations and aneuploidy toward increase of proliferation and adenoma size in Familial Adenomatous Polyposis (FAP adenomas is not known. The present study addresses these issues by investigating 147 colorectal adenomas obtained from four FAP patients. The majority of adenomas had size lower than or equal to 10 mm (86%, low grade dysplasia (63%, and were preferentially located in the right colon (60%. Normal mucosa samples were obtained from 19 healthy donors. Three synchronous adenocarcinomas were also investigated. K‐ras2 mutation spectrum was analysed by PCR and Sequence Specific Oligonucleotide (SSO hybridization, while flow cytometry (FCM was used for evaluating degree of DNA ploidy and S‐phase fraction. Overall, incidences of K‐ras2 mutations, DNA aneuploidy and high S‐phase values (>7.2% were 6.6%, 5.4% and 10.5%, respectively. In particular, among the adenomas with size lower than 5 mm, K‐ras2 mutation and DNA aneuploidy frequencies were only slightly above 1%. Statistically significant correlations were found between K‐ras2 and size, DNA ploidy and size and K‐ras2 and S‐phase (p. In particular, among the wild type K‐ras2 adenomas, high S‐phase values were detected in 8% of the cases versus 57% among the K‐ras2 mutated adenomas (p=0.0005. The present series of FAP adenomas indicates that K‐ras2 activation and gross genomic changes play a role toward a proliferative gain and tumour growth in size.

  4. Genome Instability of Chironomus riparius Mg. (Diptera, Chironomidae from Polluted Water Basins in Bulgaria

    Directory of Open Access Journals (Sweden)

    Julia Ilkova

    2014-04-01

    Full Text Available Larvae of Chironomus riparius Mg. (Chironomidae, Diptera collected from two polluted water basins in Bulgaria, the Maritsa and Chaya Rivers (adjacent to Plovdiv and Asenovgrad respectively, a small pool (near Plovdiv plus controls reared in the laboratory were studied. High concentrations of the heavy metals Pb, Cu and Cd were recorded in the sediments of the polluted stations. Marked somatic structural chromosome aberrations were found in C. riparius salivary polytene chromosomes from the field stations and their frequency was significantly higher (p<0.01 compared to the control. The observed somatic chromosome changes are discussed as a response of the chironomid genome to aquatic pollution. A new cytogenetic index based on the number of aberrations found in larvae from polluted regions in comparison with the control was applied to the data to more easily evaluate the degree of heavy metal pollution in aquatic ecosystems. Our study of a polluted site near the River Chaya showed that the somatic index was very high at 3.35 for 2010 and 11.66 for 2013 compared to 0.5 in the control. The cytogenetic index was effective in showing that all studied sites were highly polluted in comparison with the control. To determine the mechanism involved in the concentration of aberration breakpoints within specific regions of the chironomid polytene chromosome the FISH method was applied. The localization of a transposable element TFB1 along the polytene chromosomes of C. riparius was analyzed and the sites of localization were compared with breakpoints of chromosome aberrations. A significant correlation (p<0.05 was found which shows that most of the aberrations do not appear randomly but are concentrated in sites rich in transposable elements.

  5. A Bully's Bystanders Are Never Innocent

    Science.gov (United States)

    Coloroso, Barbara

    2005-01-01

    Though they play the least active role, bystanders are a critical element in bullying. With peers looking on and providing at least tacit support, the bully is no longer acting alone. The bystanders have become allies to the point of magnifying the supposed negative attributes of the target. If the bullying cycle is to be broken, the role of the…

  6. FANCG knockout CHO cells display sensitivity to diverse DNA damaging agents and possible genomic instability

    International Nuclear Information System (INIS)

    Hinz, J.M.; Tebbs, R.S.; Yamada, N.A.; Salazar, E.P.; Kopf, V.L.; Thompson, L.H.

    2003-01-01

    Full text: The function of the proteins encoded by the genes responsible for the disease Fanconi anemia (FA) have not been elucidated. Several of these proteins (FancA, C, E, F, and G) form a complex in the nucleus, and cells deficient in any one of these proteins are sensitive to crosslinking agents, suggesting a possible role for these proteins in some aspect of DNA repair, chromosomal maintenance, or replication. We constructed a FancG knockout mutant (FGKO40) in CHO AA8 cells, as well as FancG-corrected FGKO40 cells (KO40BP6, which is a pool of six BAC-clone transformants). FGKO40 cells are sensitive to a wide variety of DNA damaging agents. Sensitivity to the cross-linking agents MMC (3x) and chloroethyl-nitrosourea (3x) does not exceed that of methyl methanesulfonate (MMS) (4x), methyl-nitrosourea (4x), or ethyl-nitrosourea (3x), or the purine analog 6-thioguanine (5x). Other agents show mild sensitivity in FGKO40 cells: ionizing radiation (1.2x), UV-C (1.5x), hydroxyurea (1.2x), camptothecin (1.2x), and excess thymidine (normal). The length of S phase was carefully measured by monitoring the progression of highly synchronous G1 cells obtained by centrifugal elutriation. FGKO40 cells traversed S phase normally but had a slightly longer G2 phase than parental cells. Treatment of synchronized G1 cells with MMS did not increase S phase in parental or mutant cells, but again G2 was slightly longer for FGKO40. Mutation rates were measured at the hrpt and aprt loci, where gene inactivation confers resistance to 6-thioguanine or 8-azaadenine, respectively. FGKO40 had a slightly reduced mutation rate for hprt mutants, suggesting reduced recovery of large deletions at this locus. Moreover, the rate of methotrexate resistance was elevated 2.5-fold in mutant cells compared to controls. Resistance to this drug is generally associated with amplification of the dhfr locus, suggesting FancG plays a role in this aspect of genome stability. We suggest that the defect in FGKO

  7. An extracellular DNA mediated bystander effect produced from low dose irradiated endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Ermakov, Aleksei V., E-mail: avePlato@mail.ru [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moscow (Russian Federation); Konkova, Marina S.; Kostyuk, Svetlana V.; Smirnova, Tatiana D.; Malinovskaya, Elena M.; Efremova, Liudmila V.; Veiko, Natalya N. [Research Centre for Medical Genetics, Russian Academy of Medical Sciences, Moscow (Russian Federation)

    2011-07-01

    The human umbilical vein endothelial cells culture was exposed to X-ray radiation in a low dose of 10 cGy. The fragments of extracellular genomic DNA (ecDNA{sup R}) were isolated from the culture medium after the short-term incubation. A culture medium of unirradiated endothelial cells was then supplemented with ecDNA{sup R}, followed by analysing the cells along the series of parameters (bystander effect). The exposed cells and bystander endotheliocytes showed similar response to low doses: approximation of the 1q12 loci of chromosome 1 and their transposition into the cellular nucleus, change in shape of the endotheliocytic nucleus, activation of the nucleolus organizing regions (NORs), actin polymerization, and an elevated level of DNA double-stranded breaks. Following blockade of TLR9 receptors with oligonucleotide-inhibitor or chloroquine in the bystander cells these effects - except of activation of NORs - on exposure to ecDNA{sup R} disappeared, with no bystander response thus observed. The presence of the radiation-induced apoptosis in the bystander effect being studied suggests a possibility for radiation-modified ecDNA fragments (i.e., stress signaling factors) to be released into the culture medium, whereas inhibition of TLR9 suggests the binding these ligands to the recipient cells. A similar DNA-signaling pathway in the bystander effect we previously described for human lymphocytes. Integrity of data makes it possible to suppose that a similar signaling mechanism which we demonstrated for lymphocytes (humoral system) might also be mediated in a monolayer culture of cells (cellular tissue) after the development of the bystander effect in them and transfer of stress signaling factors (ecDNA{sup R}) through the culture medium.

  8. An extracellular DNA mediated bystander effect produced from low dose irradiated endothelial cells

    International Nuclear Information System (INIS)

    Ermakov, Aleksei V.; Konkova, Marina S.; Kostyuk, Svetlana V.; Smirnova, Tatiana D.; Malinovskaya, Elena M.; Efremova, Liudmila V.; Veiko, Natalya N.

    2011-01-01

    The human umbilical vein endothelial cells culture was exposed to X-ray radiation in a low dose of 10 cGy. The fragments of extracellular genomic DNA (ecDNA R ) were isolated from the culture medium after the short-term incubation. A culture medium of unirradiated endothelial cells was then supplemented with ecDNA R , followed by analysing the cells along the series of parameters (bystander effect). The exposed cells and bystander endotheliocytes showed similar response to low doses: approximation of the 1q12 loci of chromosome 1 and their transposition into the cellular nucleus, change in shape of the endotheliocytic nucleus, activation of the nucleolus organizing regions (NORs), actin polymerization, and an elevated level of DNA double-stranded breaks. Following blockade of TLR9 receptors with oligonucleotide-inhibitor or chloroquine in the bystander cells these effects - except of activation of NORs - on exposure to ecDNA R disappeared, with no bystander response thus observed. The presence of the radiation-induced apoptosis in the bystander effect being studied suggests a possibility for radiation-modified ecDNA fragments (i.e., stress signaling factors) to be released into the culture medium, whereas inhibition of TLR9 suggests the binding these ligands to the recipient cells. A similar DNA-signaling pathway in the bystander effect we previously described for human lymphocytes. Integrity of data makes it possible to suppose that a similar signaling mechanism which we demonstrated for lymphocytes (humoral system) might also be mediated in a monolayer culture of cells (cellular tissue) after the development of the bystander effect in them and transfer of stress signaling factors (ecDNA R ) through the culture medium.

  9. Developmental defects and genomic instability after x-irradiation of wild-type and genetically modified mouse pre-implantation and early post-implantation embryos

    International Nuclear Information System (INIS)

    Jacquet, P

    2012-01-01

    Results obtained from the end of the 1950s suggested that ionizing radiation could induce foetal malformations in some mouse strains when administered during early pre-implantation stages. Starting in 1989, data obtained in Germany also showed that radiation exposure during that period could lead to a genomic instability in the surviving foetuses. Furthermore, the same group reported that both malformations and genomic instability could be transmitted to the next generation foetuses after exposure of zygotes to relatively high doses of radiation. As such results were of concern for radiation protection, we investigated this in more detail during recent years, using mice with varying genetic backgrounds including mice heterozygous for mutations involved in important cellular processes like DNA repair, cell cycle regulation or apoptosis. The main parameters which were investigated included morphological development, genomic instability and gene expression in the irradiated embryos or their own progeny. The aim of this review is to critically reassess the results obtained in that field in the different laboratories and to try to draw general conclusions on the risks of developmental defects and genomic instability from an exposure of early embryos to moderate doses of ionizing radiation. Altogether and in the range of doses normally used in diagnostic radiology, the risk of induction of embryonic death and of congenital malformation following the irradiation of a newly fertilised egg is certainly very low when compared to the ‘spontaneous’ risks for such effects. Similarly, the risk of radiation induction of a genomic instability under such circumstances seems to be very small. However, this is not a reason to not apply some precaution principles when possible. One way of doing this is to restrict the use of higher dose examinations on all potentially pregnant women to the first ten days of their menstrual cycle when conception is very unlikely to have occurred

  10. Microsatellite instability in pediatric high grade glioma is associated with genomic profile and differential target gene inactivation.

    Directory of Open Access Journals (Sweden)

    Marta Viana-Pereira

    Full Text Available High grade gliomas (HGG are one of the leading causes of cancer-related deaths in children, and there is increasing evidence that pediatric HGG may harbor distinct molecular characteristics compared to adult tumors. We have sought to clarify the role of microsatellite instability (MSI in pediatric versus adult HGG. MSI status was determined in 144 patients (71 pediatric and 73 adults using a well established panel of five quasimonomorphic mononucleotide repeat markers. Expression of MLH1, MSH2, MSH6 and PMS2 was determined by immunohistochemistry, MLH1 was assessed for mutations by direct sequencing and promoter methylation using MS-PCR. DNA copy number profiles were derived using array CGH, and mutations in eighteen MSI target genes studied by multiplex PCR and genotyping. MSI was found in 14/71 (19.7% pediatric cases, significantly more than observed in adults (5/73, 6.8%; p = 0.02, Chi-square test. MLH1 expression was downregulated in 10/13 cases, however no mutations or promoter methylation were found. MSH6 was absent in one pediatric MSI-High tumor, consistent with an inherited mismatch repair deficiency associated with germline MSH6 mutation. MSI was classed as Type A, and associated with a remarkably stable genomic profile. Of the eighteen classic MSI target genes, we identified mutations only in MSH6 and DNAPKcs and described a polymorphism in MRE11 without apparent functional consequences in DNA double strand break detection and repair. This study thus provides evidence for a potential novel molecular pathway in a proportion of gliomas associated with the presence of MSI.

  11. Smad4 loss in mice causes spontaneous head and neck cancer with increased genomic instability and inflammation.

    Science.gov (United States)

    Bornstein, Sophia; White, Ruth; Malkoski, Stephen; Oka, Masako; Han, Gangwen; Cleaver, Timothy; Reh, Douglas; Andersen, Peter; Gross, Neil; Olson, Susan; Deng, Chuxia; Lu, Shi-Long; Wang, Xiao-Jing

    2009-11-01

    Smad4 is a central mediator of TGF-beta signaling, and its expression is downregulated or lost at the malignant stage in several cancer types. In this study, we found that Smad4 was frequently downregulated not only in human head and neck squamous cell carcinoma (HNSCC) malignant lesions, but also in grossly normal adjacent buccal mucosa. To gain insight into the importance of this observation, we generated mice in which Smad4 was deleted in head and neck epithelia (referred to herein as HN-Smad4-/- mice) and found that they developed spontaneous HNSCC. Interestingly, both normal head and neck tissue and HNSCC from HN-Smad4-/- mice exhibited increased genomic instability, which correlated with downregulated expression and function of genes encoding proteins in the Fanconi anemia/Brca (Fanc/Brca) DNA repair pathway linked to HNSCC susceptibility in humans. Consistent with this, further analysis revealed a correlation between downregulation of Smad4 protein and downregulation of the Brca1 and Rad51 proteins in human HNSCC. In addition to the above changes in tumor epithelia, both normal head and neck tissue and HNSCC from HN-Smad4-/- mice exhibited severe inflammation, which was associated with increased expression of TGF-beta1 and activated Smad3. We present what we believe to be the first single gene-knockout model for HNSCC, in which both HNSCC formation and invasion occurred as a result of Smad4 deletion. Our results reveal an intriguing connection between Smad4 and the Fanc/Brca pathway and highlight the impact of epithelial Smad4 loss on inflammation.

  12. Radiation induced genomic instability

    International Nuclear Information System (INIS)

    Morgan, W.

    2003-01-01

    This presentation will focus on delayed genetic effects occurring in the progeny of cells after exposure to ionizing radiation. We have developed a model system for investigating those genetic effects occurring multiple generations after radiation exposure. The presentation will describe some of the delayed effects observed after radiation exposures including delayed chromosomal rearrangements, and recombination events as determined by a plasmid based assay system. We will present new data on how changes in gene expression as measured by differential display and DNA microarray analysis provides a mechanism by which cells display a memory of irradiation, and introduce candidate genes that may play a role in initiating and perpetuation the unstable phenotype. These results will be discussed in terms of the recently described non-targeted Death Inducing Effect (DIE) where by secreted factors from clones of unstable cells can elicit effects in non irradiated cells and may serve to perpetuate the unstable phenotype in cells that themselves were not irradiated

  13. Investigation of genomic instability by assay of DNA fingerprint from the offspring of male mice exposed to chronic low-level γ-radiation

    International Nuclear Information System (INIS)

    Bezlepkin, V.G.; Vasil'eva, G.V.; Lomaeva, M.G.; Sirota, N.P.; Gaziev, A.I.

    2000-01-01

    By polymerase chain reaction with arbitrary primer (AP-PCR), the possibility of transmission of genome instability to somatic cells of the offspring (F 1 generation) from male parents of mice exposed to chronic low-dose γ-radiation was studied. Male mice 15 days after exposure to 10-50 cGy were mated with unirradiated females. Biopsies were taken from tale tips of two month-old mice progeny for DNA separation. Primer in the AP-PCR was 20-mer oligonucleotide flanking the micro-satellite locus Atplb2 on chromosome 11 of the mouse. Comparative analysis of individual fingerprints of AP-PCR products on DNA-templates from the offspring of irradiated and unirradiated male mice revealed an increased variability of micro-satellite-associated sequences in the genome of the offspring of males exposed to 25 and 50 cGy. DNA-fingerprints of the offspring of male mice exposed to chronic irradiation doses 10 and 25 cGy. 15 days before fertilization (at the post-meiotic stage of spermatogenesis) showed an increased frequency of non-parent bands. Result of the study point to the possibility of transmission to the offspring somatic cells of changes increasing genome instability from male parents exposed to chronic low-dose radiation prior to fertilization [ru

  14. Loss of yeast peroxiredoxin Tsa1p induces genome instability through activation of the DNA damage checkpoint and elevation of dNTP levels.

    Directory of Open Access Journals (Sweden)

    Hei-Man Vincent Tang

    2009-10-01

    Full Text Available Peroxiredoxins are a family of antioxidant enzymes critically involved in cellular defense and signaling. Particularly, yeast peroxiredoxin Tsa1p is thought to play a role in the maintenance of genome integrity, but the underlying mechanism is not understood. In this study, we took a genetic approach to investigate the cause of genome instability in tsa1Delta cells. Strong genetic interactions of TSA1 with DNA damage checkpoint components DUN1, SML1, and CRT1 were found when mutant cells were analyzed for either sensitivity to DNA damage or rate of spontaneous base substitutions. An elevation in intracellular dNTP production was observed in tsa1Delta cells. This was associated with constitutive activation of the DNA damage checkpoint as indicated by phosphorylation of Rad9/Rad53p, reduced steady-state amount of Sml1p, and induction of RNR and HUG1 genes. In addition, defects in the DNA damage checkpoint did not modulate intracellular level of reactive oxygen species, but suppressed the mutator phenotype of tsa1Delta cells. On the contrary, overexpression of RNR1 exacerbated this phenotype by increasing dNTP levels. Taken together, our findings uncover a new role of TSA1 in preventing the overproduction of dNTPs, which is a root cause of genome instability.

  15. Epigenetic Analysis of Heavy-ion Radiation Induced Bystander Effects in Mice

    Science.gov (United States)

    Zhang, Meng; Sun, Yeqing; Cui, Changna; Xue, Bei

    Abstract: Radiation-induced bystander effect was defined as the induction of damage in neighboring non-hit cells by signals released from directly-irradiated cells. Recently, low dose of high LET radiation induced bystander effects in vivo have been reported more and more. It has been indicated that radiation induced bystander effect was localized not only in bystander tissues but also in distant organs. Genomic, epigenetic and proteomics plays significant roles in regulating heavy-ion radiation stress responses in mice. To identify the molecular mechanism that underlies bystander effects of heavy-ion radiation, the male Balb/c and C57BL mice were exposed head-only to 40, 200, 2000mGy dose of (12) C heavy-ion radiation, while the rest of the animal body was shielded. Directly radiation organ ear and the distant organ liver were detected on 1h, 6h, 12h and 24h after radiation, respectively. Methylation-sensitive amplification polymorphism (MSAP) was used to monitor the level of polymorphic genomic DNA methylation changed with dose and time effects. The results show that heavy-ion irradiated mouse head could induce genomic DNA methylation changes significantly in both the directly radiation organ ear and the distant organ liver. The percent of DNA methylation changes were time-dependent and tissue-specific. Demethylation polymorphism rate was highest separately at 1 h in 200 mGy and 6 h in 2000 mGy after irradiation. The global DNA methylation changes tended to occur in the CG sites. The results illustrated that genomic methylation changes of heavy ion radiation-induced bystander effect in liver could be obvious 1 h after radiation and achieved the maximum at 6 h, while the changes could recover gradually at 12 h. The results suggest that mice head exposed to heavy-ion radiation can induce damage and methylation pattern changed in both directly radiation organ ear and distant organ liver. Moreover, our findings are important to understand the molecular mechanism of

  16. Dysregulation of mitotic machinery genes precedes genome instability during spontaneous pre-malignant transformation of mouse ovarian surface epithelial cells

    Directory of Open Access Journals (Sweden)

    Ulises Urzúa

    2016-10-01

    suggests altered control of nuclear RNA maturation, features recently linked to impaired DNA damage response leading to genome instability. These results, combined with cytogenetic analysis by other authors in this model, suggest that transcriptional profile at passage 14 might induce cytokinesis failure by which tetraploid cells approach a near-tetraploid stage containing primary chromosome aberrations that initiate the tumorigenic drive.

  17. The moyamoya disease susceptibility variant RNF213 R4810K (rs112735431) induces genomic instability by mitotic abnormality

    Energy Technology Data Exchange (ETDEWEB)

    Hitomi, Toshiaki [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Habu, Toshiyuki [Radiation Biology Center, Kyoto University, Kyoto (Japan); Kobayashi, Hatasu; Okuda, Hiroko; Harada, Kouji H. [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Osafune, Kenji [Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto (Japan); Taura, Daisuke; Sone, Masakatsu [Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Asaka, Isao; Ameku, Tomonaga; Watanabe, Akira; Kasahara, Tomoko; Sudo, Tomomi; Shiota, Fumihiko [Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto (Japan); Hashikata, Hirokuni; Takagi, Yasushi [Department of Neurosurgery, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Morito, Daisuke [Faculty of Life Sciences, Kyoto Sangyo University, Kyoto (Japan); Miyamoto, Susumu [Department of Neurosurgery, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Nakao, Kazuwa [Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Koizumi, Akio, E-mail: koizumi.akio.5v@kyoto-u.ac.jp [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan)

    2013-10-04

    Highlights: •Overexpression of RNF213 R4810K inhibited cell proliferation. •Overexpression of RNF213 R4810K had the time of mitosis 4-fold and mitotic failure. •R4810K formed a complex with MAD2 more readily than wild-type. •iPSECs from the MMD patients had elevated mitotic failure compared from the control. •RNF213 R4810K induced mitotic abnormality and increased risk of aneuploidy. -- Abstract: Moyamoya disease (MMD) is a cerebrovascular disease characterized by occlusive lesions in the Circle of Willis. The RNF213 R4810K polymorphism increases susceptibility to MMD. In the present study, we characterized phenotypes caused by overexpression of RNF213 wild type and R4810K variant in the cell cycle to investigate the mechanism of proliferation inhibition. Overexpression of RNF213 R4810K in HeLa cells inhibited cell proliferation and extended the time of mitosis 4-fold. Ablation of spindle checkpoint by depletion of mitotic arrest deficiency 2 (MAD2) did not shorten the time of mitosis. Mitotic morphology in HeLa cells revealed that MAD2 colocalized with RNF213 R4810K. Immunoprecipitation revealed an RNF213/MAD2 complex: R4810K formed a complex with MAD2 more readily than RNF213 wild-type. Desynchronized localization of MAD2 was observed more frequently during mitosis in fibroblasts from patients (n = 3, 61.0 ± 8.2%) compared with wild-type subjects (n = 6, 13.1 ± 7.7%; p < 0.01). Aneuploidy was observed more frequently in fibroblasts (p < 0.01) and induced pluripotent stem cells (iPSCs) (p < 0.03) from patients than from wild-type subjects. Vascular endothelial cells differentiated from iPSCs (iPSECs) of patients and an unaffected carrier had a longer time from prometaphase to metaphase than those from controls (p < 0.05). iPSECs from the patients and unaffected carrier had significantly increased mitotic failure rates compared with controls (p < 0.05). Thus, RNF213 R4810K induced mitotic abnormalities and increased risk of genomic instability.

  18. The moyamoya disease susceptibility variant RNF213 R4810K (rs112735431) induces genomic instability by mitotic abnormality

    International Nuclear Information System (INIS)

    Hitomi, Toshiaki; Habu, Toshiyuki; Kobayashi, Hatasu; Okuda, Hiroko; Harada, Kouji H.; Osafune, Kenji; Taura, Daisuke; Sone, Masakatsu; Asaka, Isao; Ameku, Tomonaga; Watanabe, Akira; Kasahara, Tomoko; Sudo, Tomomi; Shiota, Fumihiko; Hashikata, Hirokuni; Takagi, Yasushi; Morito, Daisuke; Miyamoto, Susumu; Nakao, Kazuwa; Koizumi, Akio

    2013-01-01

    Highlights: •Overexpression of RNF213 R4810K inhibited cell proliferation. •Overexpression of RNF213 R4810K had the time of mitosis 4-fold and mitotic failure. •R4810K formed a complex with MAD2 more readily than wild-type. •iPSECs from the MMD patients had elevated mitotic failure compared from the control. •RNF213 R4810K induced mitotic abnormality and increased risk of aneuploidy. -- Abstract: Moyamoya disease (MMD) is a cerebrovascular disease characterized by occlusive lesions in the Circle of Willis. The RNF213 R4810K polymorphism increases susceptibility to MMD. In the present study, we characterized phenotypes caused by overexpression of RNF213 wild type and R4810K variant in the cell cycle to investigate the mechanism of proliferation inhibition. Overexpression of RNF213 R4810K in HeLa cells inhibited cell proliferation and extended the time of mitosis 4-fold. Ablation of spindle checkpoint by depletion of mitotic arrest deficiency 2 (MAD2) did not shorten the time of mitosis. Mitotic morphology in HeLa cells revealed that MAD2 colocalized with RNF213 R4810K. Immunoprecipitation revealed an RNF213/MAD2 complex: R4810K formed a complex with MAD2 more readily than RNF213 wild-type. Desynchronized localization of MAD2 was observed more frequently during mitosis in fibroblasts from patients (n = 3, 61.0 ± 8.2%) compared with wild-type subjects (n = 6, 13.1 ± 7.7%; p < 0.01). Aneuploidy was observed more frequently in fibroblasts (p < 0.01) and induced pluripotent stem cells (iPSCs) (p < 0.03) from patients than from wild-type subjects. Vascular endothelial cells differentiated from iPSCs (iPSECs) of patients and an unaffected carrier had a longer time from prometaphase to metaphase than those from controls (p < 0.05). iPSECs from the patients and unaffected carrier had significantly increased mitotic failure rates compared with controls (p < 0.05). Thus, RNF213 R4810K induced mitotic abnormalities and increased risk of genomic instability

  19. Genotoxicity in the eyes of bystander cells

    International Nuclear Information System (INIS)

    Hei, Tom K.; Persaud, Rudranath; Zhou, Hongning; Suzuki, Masao

    2004-01-01

    The controversial use of a linear, no threshold extrapolation model for low dose risk assessment has become even more so in light of the recent reports on the bystander phenomenon. The answer to the question as to which of the two phenomena, bystander versus adaptive response, is more important has practical implication in terms of low dose radiation risk assessment. In this review, genotoxicity is used as an endpoint to introduce the two phenomena, provide some insight into the mechanisms of bystander effect and to bridge the two low dose phenomena which operate in opposite directions: the bystander effect tends to exaggerate the effect at low doses, by communicating damage from hit to non-hit cells whereas the adaptive response confers resistance to a subsequent challenging dose by an initial low priming dose

  20. Development of a mathematical model to study the radiation-induced bystander effect

    Energy Technology Data Exchange (ETDEWEB)

    Meireles, Sincler P. de; Santos, Adriano M.; Grynberg, Suely Epsztein, E-mail: spm@cdtn.b, E-mail: amsantos@cdtn.b, E-mail: seg@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Nunes, Maria Eugenia S., E-mail: mariaeugenia@iceb.ufop.b [Universidade Federal de Ouro Preto (UFOP), MG (Brazil)

    2011-07-01

    Living organisms are composed of millions of cells that together perform tasks of great complexity. Although every cell has an internal structure that obeys the laws of chemistry and biochemistry, it is the interactions between cells that generate a range of different phenomena. Until the 1990s it was believed that the DNA was the single molecule affected by radiation, the so-called theory of the single target. But some observations began to challenge this theory; in 1992 the bystander effect was described by Nagasawa and Little. This effect is responsible for a series of responses such as death, chromosomal instability or other abnormalities that occur in non-irradiated cells that came into contact with irradiated cells or medium from irradiated cells. Understanding the bystander effect may have important consequences for therapy and studies of low-dose risk. In this work, we have developed a computational model to study the bystander effect. This computational model is a two-dimensional cellular automata, consisting of two overlapping networks, where the first represents the cell culture, and the second one, the medium in which cells are embedded. The computational model allows the establishment of curves to describe the behavior of the effect for different levels of signals released in the irradiated medium by the irradiated cells or by the bystander cells when a second order effect is considered. The percentage of cell survival obtained from the mathematical model showed to be in good agreement with experimental data available in the literature. (author)

  1. Development of a mathematical model to study the radiation-induced bystander effect

    International Nuclear Information System (INIS)

    Meireles, Sincler P. de; Santos, Adriano M.; Grynberg, Suely Epsztein; Nunes, Maria Eugenia S.

    2011-01-01

    Living organisms are composed of millions of cells that together perform tasks of great complexity. Although every cell has an internal structure that obeys the laws of chemistry and biochemistry, it is the interactions between cells that generate a range of different phenomena. Until the 1990s it was believed that the DNA was the single molecule affected by radiation, the so-called theory of the single target. But some observations began to challenge this theory; in 1992 the bystander effect was described by Nagasawa and Little. This effect is responsible for a series of responses such as death, chromosomal instability or other abnormalities that occur in non-irradiated cells that came into contact with irradiated cells or medium from irradiated cells. Understanding the bystander effect may have important consequences for therapy and studies of low-dose risk. In this work, we have developed a computational model to study the bystander effect. This computational model is a two-dimensional cellular automata, consisting of two overlapping networks, where the first represents the cell culture, and the second one, the medium in which cells are embedded. The computational model allows the establishment of curves to describe the behavior of the effect for different levels of signals released in the irradiated medium by the irradiated cells or by the bystander cells when a second order effect is considered. The percentage of cell survival obtained from the mathematical model showed to be in good agreement with experimental data available in the literature. (author)

  2. Genome-wide analysis in UK Biobank identifies four loci associated with mood instability and genetic correlation with major depressive disorder, anxiety disorder and schizophrenia.

    Science.gov (United States)

    Ward, Joey; Strawbridge, Rona J; Bailey, Mark E S; Graham, Nicholas; Ferguson, Amy; Lyall, Donald M; Cullen, Breda; Pidgeon, Laura M; Cavanagh, Jonathan; Mackay, Daniel F; Pell, Jill P; O'Donovan, Michael; Escott-Price, Valentina; Smith, Daniel J

    2017-11-30

    Mood instability is a core clinical feature of affective and psychotic disorders. In keeping with the Research Domain Criteria approach, it may be a useful construct for identifying biology that cuts across psychiatric categories. We aimed to investigate the biological validity of a simple measure of mood instability and evaluate its genetic relationship with several psychiatric disorders, including major depressive disorder (MDD), bipolar disorder (BD), schizophrenia, attention deficit hyperactivity disorder (ADHD), anxiety disorder and post-traumatic stress disorder (PTSD). We conducted a genome-wide association study (GWAS) of mood instability in 53,525 cases and 60,443 controls from UK Biobank, identifying four independently associated loci (on chromosomes 8, 9, 14 and 18), and a common single-nucleotide polymorphism (SNP)-based heritability estimate of ~8%. We found a strong genetic correlation between mood instability and MDD (r g  = 0.60, SE = 0.07, p = 8.95 × 10 -17 ) and a small but significant genetic correlation with both schizophrenia (r g  = 0.11, SE = 0.04, p = 0.01) and anxiety disorders (r g  = 0.28, SE = 0.14, p = 0.04), although no genetic correlation with BD, ADHD or PTSD was observed. Several genes at the associated loci may have a role in mood instability, including the DCC netrin 1 receptor (DCC) gene, eukaryotic translation initiation factor 2B subunit beta (eIF2B2), placental growth factor (PGF) and protein tyrosine phosphatase, receptor type D (PTPRD). Strengths of this study include the very large sample size, but our measure of mood instability may be limited by the use of a single question. Overall, this work suggests a polygenic basis for mood instability. This simple measure can be obtained in very large samples; our findings suggest that doing so may offer the opportunity to illuminate the fundamental biology of mood regulation.

  3. Are Victims Truly Worse Off in the Presence of Bystanders? Revisiting the Bystander Effect

    NARCIS (Netherlands)

    Fromell, Hanna; Nosenzo, Daniele; Owens, Trudy; Tufano, Fabio

    2017-01-01

    Previous studies have shown that individuals are less likely to help a person in need when there are “bystanders” present who can also offer help. We designed an experiment to re-examine this “bystander effect” using modified dictator games. We find lower giving rates in the presence of bystanders,

  4. Bystander Programs: Accommodating or Derailing Sexism?

    Directory of Open Access Journals (Sweden)

    Adam Reid

    2017-09-01

    Full Text Available Bystander programs implemented to meet federal requirements to reduce sexual assaults on college campuses in the United States must include primary prevention. Survey data (n = 280 and interview data (n = 20 presented in this paper explore students’ hypothetical and actual willingness to intervene as bystanders. Although most students surveyed (57% claim they would be very likely to intervene, fewer than half would be very suspicious of someone leading away an intoxicated individual at a party (45% of women and 28% of men: p < 0.01. Interview data reveal how students perceive risk factors at college parties and what types of bystander measures they attempt, including “distractions”, a nonconfrontational tactic in which bystanders avoid more direct but socially risky interventions. Subsumed in many current bystander programs is an invisible element of valorizing harmony. Condoning bystanders’ unwillingness to directly confront seemingly predatory individuals could make change seem out of reach and could also embolden offenders whose behavior is observed and only temporarily thwarted.

  5. Radiation-induced bystander effects enhanced by elevated sodium chloride through sensitizing cells to bystander factors

    International Nuclear Information System (INIS)

    Zhu Lingyan; Han Wei; Chen Shaopeng; Zhao Ye; Jiang Erkang; Bao Lingzhi; Pei Bei; Yang Gen; Zhao Guoping; Wang Jun; Xu An; Wu Lijun

    2008-01-01

    Radiation-induced bystander effects (RIBE) have been demonstrated to occur widely in various cell lines. However, very little data is available on the genotoxic effects of RIBE combined with other factor(s). We reported previously that with a low dose of α-particle irradiation, the fraction of γ-H2AX foci-positive cells in non-irradiated bystander cells was significantly increased under elevated NaCl culture conditions. In this study, we further investigated the functional role of NaCl in the enhancement of RIBE using a specially designed co-culture system and micronucleus (MN) test. It was shown that the MN frequency was not increased significantly by elevated NaCl (9.0 g/L) alone or by medium exposure. However, with 1.0 cGy α-particle irradiation, the induced MN frequency increased significantly in both irradiated and non-irradiated bystander regions. Additional studies showed that elevated NaCl made the non-irradiated bystander cells more vulnerable to bystander factors. Furthermore, it was found that the induced MN frequency in cells both in irradiated and non-irradiated bystander regions was weakened when the hypertonic medium was changed to normotonic medium for 2 h before irradiation. Such observations were quite similar to the co-effect of NaCl and hydrogen peroxide (H 2 O 2 ), indicating that elevated NaCl might sensitize non-irradiated cells to bystander factors-induced oxidative stress

  6. Genomic instability in mutation induction on normal human fibroblasts irradiated with chronic low-dose radiations in heavy-ion radiation field

    International Nuclear Information System (INIS)

    Suzuki, M.; Tsuruoka, C.; Uchihori, Y.; Yasuda, H.; Fujitaka, K.

    2003-01-01

    Full text: At a time when manned space exploration is more a reality with the planned the International Space Station (ISS) underway, the potential exposure of crews in a spacecraft to chronic low-dose radiations in the field of low-flux galactic cosmic rays (GCR) and the subsequent biological effects have become one of the major concerns of space science. We have studied both in vitro life span and genomic instability in cellular effects in normal human skin fibroblasts irradiated with chronic low-dose radiations in heavy-ion radiation field. Cells were cultured in a CO2 incubator, which was set in the irradiation room for the biological study of heavy ions in the Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences (NIRS), and irradiated with scattered radiations produced from heavy ions. Absorbed dose measured using a thermoluminescence dosimeter (TLD) and a Si-semiconductor detector was to be around 1.4 mGy per day when operating the HIMAC machine for biological experiments. The total population doubling number (tPDN) of low-dose irradiated cells was significantly smaller (79-93%) than that of unirradiated cells. The results indicate that the life span of the cell population shortens by irradiating with low-dose scattered radiations in the heavy-ion irradiation field. Genomic instability in cellular responses was examined to measure either cell killing or mutation induction in low-dose accumulated cells after exposing to X-ray challenging doses. The results showed that there was no enhanced effect on cell killing between low-dose accumulated and unirradiated cells after exposing to defined challenging doses of 200kV X rays. On the contrary, the mutation frequency on hprt locus of low-dose accumulated cells was much higher than that of unirradiated cells. The results suggested that genomic instability was induced in mutagenesis by the chronic low-dose irradiations in heavy-ion radiation field

  7. The bystander effect of cancer gene therapy

    International Nuclear Information System (INIS)

    Lumniczky, K.; Safrany, G.

    2008-01-01

    Cancer gene therapy is a new, promising therapeutic agent. In the clinic, it should be used in combination with existing modalities, such as tumour irradiation. First, we summarise the most important fields of cancer gene therapy: gene directed enzyme pro-drug therapy; the activation of an anti-tumour immune attack; restoration of the wild type p53 status; the application of new, replication competent and oncolytic viral vectors; tumour specific, as well as radiation- and hypoxia-induced gene expression. Special emphasizes are put on the combined effect of these modalities with local tumour irradiation. Using the available vector systems, only a small portion of the cancer cells will contain the therapeutic genes under therapeutic situations. Bystander cell killing might contribute to the success of various gene therapy protocols. We summarise the evidences that lethal bystander effects may occur during cancer gene therapy. Bystander effects are especially important in the gene directed enzyme pro-drug therapy. There, bystander cell killing might have different routes: cell communication through gap junction intercellular contacts; release of toxic metabolites into the neighbourhood or to larger distances; phagocytosis of apoptotic bodies; and the activation of the immune system. Bystander cell killing can be enhanced by the introduction of gap junction proteins into the cells, by further activating the immune system with immune-stimulatory molecules, or by introducing genes into the cells that help the transfer of cytotoxic genes and / or metabolites into the bystander cells. In conclusion, there should be additional improvements in cancer gene therapy for the more efficient clinical application. (orig.)

  8. Rethinking the bystander role in school violence prevention.

    Science.gov (United States)

    Stueve, Ann; Dash, Kimberly; O'Donnell, Lydia; Tehranifar, Parisa; Wilson-Simmons, Renée; Slaby, Ronald G; Link, Bruce G

    2006-01-01

    Public concerns about school shootings and safety draw attention to the role bystanders can play in preventing school violence. Although school violence prevention plans are often required, there is little guidance about whether these should address the roles of bystanders and what actions bystanders should take in different circumstances, from more common instances of bullying and fighting to rare, but potentially lethal, threats and use of weapons. Literature pertaining to bystanders is reviewed and applied to the school setting. The definition of bystander is expanded, including parents, teachers, and other school staff as well as youths and those who have information about potential violence as well as those who witness its occurrence. Barriers preventing bystanders from taking positive actions are discussed. The authors call on health promotion researchers and practitioners to work with school communities to identify norms, attitudes, and outcome expectancies that shape bystander behaviors to inform prevention efforts.

  9. Suppression of Genomic Instabilities Caused by Chromosome Mis-segregation: A Perspective From Studying BubR1 and Sgo1

    Science.gov (United States)

    Dai, Wei

    2013-01-01

    Aneuploidy is a major manifestation of chromosomal instability, which is defined as a numerical abnormality of chromosomes in diploid cells. It is highly prevalent in a variety of human malignancies. Increased chromosomal instability is the major driving force for tumor development and progression. To suppress genomic stability during cell division, eukaryotic cells have evolved important molecular mechanisms, commonly referred to as checkpoints. The spindle checkpoint ensures that cells with defective mitotic spindles or a defective interaction between the spindles and kinetochores do not initiate chromosomal segregation during mitosis. Extensive studies have identified and characterized more than a dozen genes that play important roles in the regulation of the spindle checkpoint in mammalian cells. During the past decade, we have carried out extensive investigation of the role of BubR1 (Bub1-related kinase) and Sgo1 (shugoshin 1), two important gene products that safeguard accurate chromosome segregation during mitosis. This mini-review summarizes our studies, as well as those by other researchers in the field, on the functions of these two checkpoint proteins and their molecular regulation during mitosis. Further elucidation of the molecular mechanisms of the spindle checkpoint regulation has the potential to identify important mitotic targets for rational anticancer drug design. PMID:20040454

  10. Suppression of Genomic Instabilities Caused by Chromosome Mis-segregation: A Perspective From Studying BubR1 and Sgo1

    Directory of Open Access Journals (Sweden)

    Wei Dai

    2009-12-01

    Full Text Available Aneuploidy is a major manifestation of chromosomal instability, which is defined as a numerical abnormality of chromosomes in diploid cells. It is highly prevalent in a variety of human malignancies. Increased chromosomal instability is the major driving force for tumor development and progression. To suppress genomic stability during cell division, eukaryotic cells have evolved important molecular mechanisms, commonly referred to as checkpoints. The spindle checkpoint ensures that cells with defective mitotic spindles or a defective interaction between the spindles and kinetochores do not initiate chromosomal segregation during mitosis. Extensive studies have identified and characterized more than a dozen genes that play important roles in the regulation of the spindle checkpoint in mammalian cells. During the past decade, we have carried out extensive investigation of the role of BubR1 (Bub1-related kinase and Sgo1 (shugoshin 1, two important gene products that safeguard accurate chromosome segregation during mitosis. This mini-review summarizes our studies, as well as those by other researchers in the field, on the functions of these two checkpoint proteins and their molecular regulation during mitosis. Further elucidation of the molecular mechanisms of the spindle checkpoint regulation has the potential to identify important mitotic targets for rational anticancer drug design.

  11. Detection of genomic instability in descendants of male mice exposed to chronic low-level gamma-radiation using the test 'adaptive response'

    International Nuclear Information System (INIS)

    Rozanova, O.M.; Zaichkina, S.I.; Akhmadieva, A.; Aptikaeva, G.F.; Klokov, D.J.

    2003-01-01

    Full text: The goal of the present study was to examine whether the genomic instability can be revealed in vivo using the test 'adaptive response' (AR). Two-month-old BALB/C male mice were subjected to chronic irradiation in the gamma-field with a dose of 0.1 Gy (0.01 Gy/day) and a dose of 0.5 Gy (0.01 and 0.05 Gy/day). Control animals were kept under similar conditions but without irradiation. Fifteen days after the irradiation, males from the irradiated and control groups were mated in separate cages with unirradiated females for 2 weeks. The males, descendants from irradiated and unirradiated parents, at an age of two months were subjected to additional irradiation with a dose of 1.5 Gy. To reveal the genetic instability using the AR test, another group of males, the descendants from irradiated and unirradiated parents, were exposed to acute irradiation by the scheme of AR: with an adapting dose (D1) of 0.1 Gy (0.125 Gy/min) followed after a day by a challenging dose (D2) of 1.5 Gy (0.47 Gy/min). After 28 h, the animals of all groups were killed. Bone marrow specimens for calculating micronuclei (MN) in polychromatophyl erythrocytes (PCE) were prepared. It was found that in descendants that resulted from unirradiated parents and the parents irradiated with a dose of 0.1 Gy, the percentages of PCE with injuries were nearly equal. Upon irradiation of parents with a dose of 0.5 Gy, the percentage of PCE with MN in descendants increased. The examination of radiosensitivity of descendants from irradiated parents showed that the percentage of PCE with MN decreased three-to-fourfold (depending on the dose of irradiation of the parents) compared to descendants from unirradiated parents. If the descendants from exposed parents were irradiated by the scheme of AR, no AR was observed. Thus, the experimental data indicated that, it is possible to detect the transition of gamma-radiation-induced genomic instability in sex cells of male parents into somatic cells of mice (F1

  12. Bystanders not so innocent after all.

    Science.gov (United States)

    Batten, Marcel; Ghilardi, Nico

    2012-06-29

    Interleukin 27 (IL-27) regulates immune responses, including T helper 17 (Th17) cell activity. In this issue of Immunity, Hirahara et al. (2012) demonstrate that IL-27 suppresses Th17 cells in trans through induction of the inhibitory ligand PD-L1 on bystander T cells. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Phyllanthus emblica Fruit Extract Activates Spindle Assembly Checkpoint, Prevents Mitotic Aberrations and Genomic Instability in Human Colon Epithelial NCM460 Cells

    Directory of Open Access Journals (Sweden)

    Xihan Guo

    2016-09-01

    Full Text Available The fruit of Phyllanthus emblica Linn. (PE has been widely consumed as a functional food and folk medicine in Southeast Asia due to its remarkable nutritional and pharmacological effects. Previous research showed PE delays mitotic progress and increases genomic instability (GIN in human colorectal cancer cells. This study aimed to investigate the similar effects of PE by the biomarkers related to spindle assembly checkpoint (SAC, mitotic aberrations and GIN in human NCM460 normal colon epithelial cells. Cells were treated with PE and harvested differently according to the biomarkers observed. Frequencies of micronuclei (MN, nucleoplasmic bridge (NPB and nuclear bud (NB in cytokinesis-block micronucleus assay were used as indicators of GIN. Mitotic aberrations were assessed by the biomarkers of chromosome misalignment, multipolar division, chromosome lagging and chromatin bridge. SAC activity was determined by anaphase-to- metaphase ratio (AMR and the expression of core SAC gene budding uninhibited by benzimidazoles related 1 (BubR1. Compared with the control, PE-treated cells showed (1 decreased incidences of MN, NPB and NB (p < 0.01; (2 decreased frequencies of all mitotic aberration biomarkers (p < 0.01; and (3 decreased AMR (p < 0.01 and increased BubR1 expression (p < 0.001. The results revealed PE has the potential to protect human normal colon epithelial cells from mitotic and genomic damages partially by enhancing the function of SAC.

  14. Radiation-induced bystander effects enhanced by elevated sodium chloride through sensitizing cells to bystander factors

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Lingyan; Han Wei; Chen Shaopeng; Zhao Ye; Jiang Erkang; Bao Lingzhi; Pei Bei; Yang Gen; Zhao Guoping; Wang Jun; Xu An [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, Anhui (China); Wu Lijun [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, Anhui (China)], E-mail: ljw@ipp.ac.cn

    2008-09-26

    Radiation-induced bystander effects (RIBE) have been demonstrated to occur widely in various cell lines. However, very little data is available on the genotoxic effects of RIBE combined with other factor(s). We reported previously that with a low dose of {alpha}-particle irradiation, the fraction of {gamma}-H2AX foci-positive cells in non-irradiated bystander cells was significantly increased under elevated NaCl culture conditions. In this study, we further investigated the functional role of NaCl in the enhancement of RIBE using a specially designed co-culture system and micronucleus (MN) test. It was shown that the MN frequency was not increased significantly by elevated NaCl (9.0 g/L) alone or by medium exposure. However, with 1.0 cGy {alpha}-particle irradiation, the induced MN frequency increased significantly in both irradiated and non-irradiated bystander regions. Additional studies showed that elevated NaCl made the non-irradiated bystander cells more vulnerable to bystander factors. Furthermore, it was found that the induced MN frequency in cells both in irradiated and non-irradiated bystander regions was weakened when the hypertonic medium was changed to normotonic medium for 2 h before irradiation. Such observations were quite similar to the co-effect of NaCl and hydrogen peroxide (H{sub 2}O{sub 2}), indicating that elevated NaCl might sensitize non-irradiated cells to bystander factors-induced oxidative stress.

  15. [Radiation-induced bystander effect: the important part of ionizing radiation response. Potential clinical implications].

    Science.gov (United States)

    Wideł, Maria; Przybyszewski, Waldemar; Rzeszowska-Wolny, Joanna

    2009-08-18

    It has long been a central radiobiological dogma that the damaging effects of ionizing radiation, such as cell death, cytogenetic changes, apoptosis, mutagenesis, and carcinogenesis, are the results of the direct ionization of cell structures, particularly DNA, or indirect damage via water radiolysis products. However, several years ago attention turned to a third mechanism of radiation, termed the "bystander effect" or "radiation-induced bystander effect" (RIBE). This is induced by agents and signals emitted by directly irradiated cells and manifests as a lowering of survival, cytogenetic damage, apoptosis enhancement, and biochemical changes in neighboring non-irradiated cells. The bystander effect is mainly observed in in vitro experiments using very low doses of alpha particles (range; mGy, cGy), but also after conventional irradiation (X-rays, gamma rays) at low as well as conventional doses. The mechanisms responsible for the bystander effect are complex and still poorly understood. It is believed that molecular signals released from irradiated cells induce different signaling ways in non-irradiated neighboring cells, leading to the observed events. The molecular signals may be transmitted through gap junction intercellular communication and through a medium transfer mechanism. The nature of these transmitted factors are diverse, and still not definitely established. It seems that RIBE may have important clinical implications for health risk associated with radiation exposure. Potentially, this effect may have important implications in the creation of whole-body or localized side effects in tissues beyond the irradiation field and also in low-dose radiological and radioisotope diagnostics. Factors emitted by irradiated cells may result in the risk of genetic instability, mutations, and second primary cancer induction. They might also have their own part in inducing and extending post-radiation side effects in normal tissue. The bystander effect may be a

  16. Radiation-induced bystander effect: The important part of ionizing radiation response. Potential clinical implications

    Directory of Open Access Journals (Sweden)

    Maria Wideł

    2009-08-01

    Full Text Available It has long been a central radiobiological dogma that the damaging effects of ionizing radiation, such as cell death, cytogenetic changes, apoptosis, mutagenesis, and carcinogenesis, are the results of the direct ionization of cell structures, particularly DNA, or indirect damage via water radiolysis products. However, several years ago attention turned to a third mechanism of radiation, termed the “bystander effect” or “radiation-induced bystander effect” (RIBE. This is induced by agents and signals emitted by directly irradiated cells and manifests as a lowering of survival, cytogenetic damage, apoptosis enhancement, and biochemical changes in neighboring non-irradiated cells. The bystander effect is mainly observed in in vitro experiments using very low doses of alpha particles (range; mGy, cGy, but also after conventional irradiation (X-rays, gamma rays at low as well as conventional doses. The mechanisms responsible for the bystander effect are complex and still poorly understood. It is believed that molecular signals released from irradiated cells induce different signaling ways in non-irradiated neighboring cells, leading to the observed events. The molecular signals may be transmitted through gap junction intercellular communication and through a medium transfer mechanism. The nature of these transmitted factors are diverse, and still not defi nitely established. It seems that RIBE may have important clinical implications for health risk associated with radiation exposure. Potentially, this effectmay have important implications in the creation of whole-body or localized side effects in tissues beyond the irradiation fi eld and also in low-dose radiological and radioisotope diagnostics. Factors emitted by irradiated cells may result in the risk of genetic instability, mutations, and second primary cancer induction. They might also have their own part in inducing and extending post-radiation side effects in normal tissue. The

  17. Cell damage from radiation-induced bystander effects for different cell densities simulated by a mathematical model via cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Meireles, Sincler P. de; Santos, Adriano M.; Grynberg, Suely Epsztein, E-mail: spm@cdtn.b, E-mail: amsantos@cdtn.b, E-mail: seg@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Nunes, Maria Eugenia S., E-mail: mariaeugenia@iceb.ufop.b [Universidade Federal de Ouro Preto (UFOP), MG (Brazil)

    2011-07-01

    During recent years, there has been a shift from an approach focused entirely on DNA as the main target of ionizing radiation to a vision that considers complex signaling pathways in cells and among cells within tissues. Several newly recognized responses were classified as the so-called non-target responses in which the biological effects are not directly related to the amount of energy deposited in the DNA of cells that were traversed by radiation. In 1992 the bystander effect was described referring to a series of responses such as death, chromosomal instability or other abnormalities that occur in non-irradiated cells that came into contact with irradiated cells or medium from irradiated cells. In this work, we have developed a mathematical model via cellular automata, to quantify cell death induced by the bystander effect. The model is based on experiments with irradiated cells conditioned medium which suggests that irradiated cells secrete molecules in the medium that are capable of damaging other cells. The computational model consists of two-dimensional cellular automata which is able to simulate the transmission of bystander signals via extrinsic route and via Gap junctions. The model has been validated by experimental results in the literature. The time evolution of the effect and the dose-response curves were obtained in good accordance to them. Simulations were conducted for different values of bystander and irradiated cell densities with constant dose. From this work, we have obtained a relationship between cell density and effect. (author)

  18. Cell damage from radiation-induced bystander effects for different cell densities simulated by a mathematical model via cellular automata

    International Nuclear Information System (INIS)

    Meireles, Sincler P. de; Santos, Adriano M.; Grynberg, Suely Epsztein; Nunes, Maria Eugenia S.

    2011-01-01

    During recent years, there has been a shift from an approach focused entirely on DNA as the main target of ionizing radiation to a vision that considers complex signaling pathways in cells and among cells within tissues. Several newly recognized responses were classified as the so-called non-target responses in which the biological effects are not directly related to the amount of energy deposited in the DNA of cells that were traversed by radiation. In 1992 the bystander effect was described referring to a series of responses such as death, chromosomal instability or other abnormalities that occur in non-irradiated cells that came into contact with irradiated cells or medium from irradiated cells. In this work, we have developed a mathematical model via cellular automata, to quantify cell death induced by the bystander effect. The model is based on experiments with irradiated cells conditioned medium which suggests that irradiated cells secrete molecules in the medium that are capable of damaging other cells. The computational model consists of two-dimensional cellular automata which is able to simulate the transmission of bystander signals via extrinsic route and via Gap junctions. The model has been validated by experimental results in the literature. The time evolution of the effect and the dose-response curves were obtained in good accordance to them. Simulations were conducted for different values of bystander and irradiated cell densities with constant dose. From this work, we have obtained a relationship between cell density and effect. (author)

  19. Correlation of MLH1 and MGMT expression and promoter methylation with genomic instability in patients with thyroid carcinoma

    International Nuclear Information System (INIS)

    Santos, Juliana Carvalho; Bastos, André Uchimura; Cerutti, Janete Maria; Ribeiro, Marcelo Lima

    2013-01-01

    Gene silencing of the repair genes MLH1 and MGMT was shown to be a mechanism underlying the development of microsatellite instability (MSI), a phenotype frequently associated with various human malignancies. Recently, aberrant methylation of MLH1, MGMT and MSI were shown to be associated with mutations in genes such as BRAF, RAS and IDH1 in colon and brain tumours. Little is known about the methylation status of MLH1 and MGMT in thyroid tumours and its association with MSI and mutational status. In a series of 96 thyroid tumours whose mutational profiles of BRAF, IDH1 and NRAS mutations and RET/PTC were previously determined, we investigated MLH1 and MGMT expression and methylation status by qPCR and methylation-specific PCR after bisulphite treatment, respectively. MSI was determined by PCR using seven standard microsatellite markers. Samples with point mutations (BRAF, IDH1 and NRAS) show a decrease in MLH1 expression when compared to negative samples. Additionally, malignant lesions show a higher MSI pattern than benign lesions. The MSI phenotype was also associated with down-regulation of MLH1. The results of this study allow us to conclude that low expression of MLH1 is associated with BRAF V600E mutations, RET/PTC rearrangements and transitions (IDH1 and NRAS) in patients with thyroid carcinoma. In addition, a significant relationship between MSI status and histological subtypes was found

  20. 56Fe particle exposure results in a long-lasting increase in a cellular index of genomic instability and transiently suppresses adult hippocampal neurogenesis in vivo

    Science.gov (United States)

    DeCarolis, Nathan A.; Rivera, Phillip D.; Ahn, Francisca; Amaral, Wellington Z.; LeBlanc, Junie A.; Malhotra, Shveta; Shih, Hung-Ying; Petrik, David; Melvin, Neal R.; Chen, Benjamin P. C.; Eisch, Amelia J.

    2014-07-01

    The high-LET HZE particles from galactic cosmic radiation pose tremendous health risks to astronauts, as they may incur sub-threshold brain injury or maladaptations that may lead to cognitive impairment. The health effects of HZE particles are difficult to predict and unfeasible to prevent. This underscores the importance of estimating radiation risks to the central nervous system as a whole as well as to specific brain regions like the hippocampus, which is central to learning and memory. Given that neurogenesis in the hippocampus has been linked to learning and memory, we investigated the response and recovery of neurogenesis and neural stem cells in the adult mouse hippocampal dentate gyrus after HZE particle exposure using two nestin transgenic reporter mouse lines to label and track radial glia stem cells (Nestin-GFP and Nestin-CreERT2/R26R:YFP mice, respectively). Mice were subjected to 56Fe particle exposure (0 or 1 Gy, at either 300 or 1000 MeV/n) and brains were harvested at early (24 h), intermediate (7 d), and/or long time points (2-3 mo) post-irradiation. 56Fe particle exposure resulted in a robust increase in 53BP1+ foci at both the intermediate and long time points post-irradiation, suggesting long-term genomic instability in the brain. However, 56Fe particle exposure only produced a transient decrease in immature neuron number at the intermediate time point, with no significant decrease at the long time point post-irradiation. 56Fe particle exposure similarly produced a transient decrease in dividing progenitors, with fewer progenitors labeled at the early time point but equal number labeled at the intermediate time point, suggesting a recovery of neurogenesis. Notably, 56Fe particle exposure did not change the total number of nestin-expressing neural stem cells. These results highlight that despite the persistence of an index of genomic instability, 56Fe particle-induced deficits in adult hippocampal neurogenesis may be transient. These data support

  1. Bystander Tactics: Life on Turf in Karachi

    Directory of Open Access Journals (Sweden)

    Tania Ahmad

    2012-03-01

    Full Text Available This article posits an analytic of the bystander, as a supplement to studies of perpetrators and victims, in relation to political affiliation, mobilization and violence in Karachi. In particular, I use ethnographic findings to elucidate the tactics of anticipation used by Karachi residents of neighborhoods widely considered the turf of the Muttahida Qaumi Movement (MQM. The examples of students’ and teachers’ reactions to a college rumble between rival groups, parents’ attempts to keep their sons from being recruited into party politics, and young people confident in their ability to navigate an economy of affiliation demonstrate a range of bystander tactics, in which subjection and subversion are aligned. Although metanarratives of democratization frequently elide the everyday activity of standing by, it constitutes a pervasive mode of participation in Karachi’s political landscape.

  2. Neutron induced bystander effect among zebrafish embryos

    Science.gov (United States)

    Ng, C. Y. P.; Kong, E. Y.; Kobayashi, A.; Suya, N.; Uchihori, Y.; Cheng, S. H.; Konishi, T.; Yu, K. N.

    2015-12-01

    The present paper reported the first-ever observation of neutron induced bystander effect (NIBE) using zebrafish (Danio rerio) embryos as the in vivo model. The neutron exposure in the present work was provided by the Neutron exposure Accelerator System for Biological Effect Experiments (NASBEE) facility at the National Institute of Radiological Sciences (NIRS), Chiba, Japan. Two different strategies were employed to induce NIBE, namely, through directly partnering and through medium transfer. Both results agreed with a neutron-dose window (20-50 mGy) which could induce NIBE. The lower dose limit corresponded to the threshold amount of neutron-induced damages to trigger significant bystander signals, while the upper limit corresponded to the onset of gamma-ray hormesis which could mitigate the neutron-induced damages and thereby suppress the bystander signals. Failures to observe NIBE in previous studies were due to using neutron doses outside the dose-window. Strategies to enhance the chance of observing NIBE included (1) use of a mono-energetic high-energy (e.g., between 100 keV and 2 MeV) neutron source, and (2) use of a neutron source with a small gamma-ray contamination. It appeared that the NASBEE facility used in the present study fulfilled both conditions, and was thus ideal for triggering NIBE.

  3. Bystander-witnessed cardiac arrest is associated with reported agonal breathing and leads to less frequent bystander CPR.

    Science.gov (United States)

    Brinkrolf, P; Metelmann, B; Scharte, C; Zarbock, A; Hahnenkamp, K; Bohn, A

    2018-04-18

    Although the importance of bystander cardiopulmonary resuscitation has been shown in multiple studies, the rate of bystander cardiopulmonary resuscitation is still relatively low in many countries. Little is known on bystanders' perceptions influencing the decision to start cardiopulmonary resuscitation. Our study aims to determine such factors. Semi-structured telephone interviews with bystanders of out-of-hospital cardiac arrests between December 2014 and April 2016 were performed in a prospective manner. This single-center survey was conducted in the city of Münster, Germany. The bystander's sex and age, the perception of the victim's breathing and initial condition were correlated with the share of bystander cardiopulmonary resuscitation in the corresponding group. 101 telephone interviews were performed with 57 male and 44 female participants showing a mean age of 52.7 (SD ± 16.3). In case of apnoea 38 out of 46 bystanders (82.6%) started cardiopulmonary resuscitation; while in case of descriptions indicating agonal breathing 19 out of 35 bystanders (54.3%) started cardiopulmonary resuscitation (p = .007). If the patient was found unconscious 47 out of 63 bystanders (74.7%) performed cardiopulmonary resuscitation, while in cases of witnessed cardiac arrest 19 out of 38 bystanders (50%) attempted cardiopulmonary resuscitation (p = .012). Witnessed change of consciousness is an independent factor significantly lowering the probability of starting cardiopulmonary resuscitation (regression coefficient -1.489, p bystander-CPR was started. These data reinforce the importance of teaching the recognition of early cardiac arrest. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Ataxia-telangiectasia mutated (ATM) deficiency decreases reprogramming efficiency and leads to genomic instability in iPS cells

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Taisuke [Department of Cell Differentiation, The Sakaguchi Laboratory, School of Medicine, Keio University, Tokyo 160-8582 (Japan); Nagamatsu, Go, E-mail: gonag@sc.itc.keio.ac.jp [Department of Cell Differentiation, The Sakaguchi Laboratory, School of Medicine, Keio University, Tokyo 160-8582 (Japan); Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan); Kosaka, Takeo [Department of Urology, School of Medicine, Keio University, Tokyo 160-8582 (Japan); Takubo, Keiyo [Department of Cell Differentiation, The Sakaguchi Laboratory, School of Medicine, Keio University, Tokyo 160-8582 (Japan); Hotta, Akitsu [Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan); Department of Reprogramming Science, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto (Japan); Ellis, James [Ontario Human iPS Cell Facility, Molecular Genetics, University of Toronto, Developmental and Stem Cell Biology, SickKids, Toronto, Canada MG1L7 (Canada); Suda, Toshio, E-mail: sudato@sc.itc.keio.ac.jp [Department of Cell Differentiation, The Sakaguchi Laboratory, School of Medicine, Keio University, Tokyo 160-8582 (Japan)

    2011-04-08

    Highlights: {yields} iPS cells were induced with a fluorescence monitoring system. {yields} ATM-deficient tail-tip fibroblasts exhibited quite a low reprogramming efficiency. {yields} iPS cells obtained from ATM-deficient cells had pluripotent cell characteristics. {yields} ATM-deficient iPS cells had abnormal chromosomes, which were accumulated in culture. -- Abstract: During cell division, one of the major features of somatic cell reprogramming by defined factors, cells are potentially exposed to DNA damage. Inactivation of the tumor suppressor gene p53 raised reprogramming efficiency but resulted in an increased number of abnormal chromosomes in established iPS cells. Ataxia-telangiectasia mutated (ATM), which is critical in the cellular response to DNA double-strand breaks, may also play an important role during reprogramming. To clarify the function of ATM in somatic cell reprogramming, we investigated reprogramming in ATM-deficient (ATM-KO) tail-tip fibroblasts (TTFs). Although reprogramming efficiency was greatly reduced in ATM-KO TTFs, ATM-KO iPS cells were successfully generated and showed the same proliferation activity as WT iPS cells. ATM-KO iPS cells had a gene expression profile similar to ES cells and WT iPS cells, and had the capacity to differentiate into all three germ layers. On the other hand, ATM-KO iPS cells accumulated abnormal genome structures upon continuous passages. Even with the abnormal karyotype, ATM-KO iPS cells retained pluripotent cell characteristics for at least 20 passages. These data indicate that ATM does participate in the reprogramming process, although its role is not essential.

  5. Ataxia-telangiectasia mutated (ATM) deficiency decreases reprogramming efficiency and leads to genomic instability in iPS cells

    International Nuclear Information System (INIS)

    Kinoshita, Taisuke; Nagamatsu, Go; Kosaka, Takeo; Takubo, Keiyo; Hotta, Akitsu; Ellis, James; Suda, Toshio

    2011-01-01

    Highlights: → iPS cells were induced with a fluorescence monitoring system. → ATM-deficient tail-tip fibroblasts exhibited quite a low reprogramming efficiency. → iPS cells obtained from ATM-deficient cells had pluripotent cell characteristics. → ATM-deficient iPS cells had abnormal chromosomes, which were accumulated in culture. -- Abstract: During cell division, one of the major features of somatic cell reprogramming by defined factors, cells are potentially exposed to DNA damage. Inactivation of the tumor suppressor gene p53 raised reprogramming efficiency but resulted in an increased number of abnormal chromosomes in established iPS cells. Ataxia-telangiectasia mutated (ATM), which is critical in the cellular response to DNA double-strand breaks, may also play an important role during reprogramming. To clarify the function of ATM in somatic cell reprogramming, we investigated reprogramming in ATM-deficient (ATM-KO) tail-tip fibroblasts (TTFs). Although reprogramming efficiency was greatly reduced in ATM-KO TTFs, ATM-KO iPS cells were successfully generated and showed the same proliferation activity as WT iPS cells. ATM-KO iPS cells had a gene expression profile similar to ES cells and WT iPS cells, and had the capacity to differentiate into all three germ layers. On the other hand, ATM-KO iPS cells accumulated abnormal genome structures upon continuous passages. Even with the abnormal karyotype, ATM-KO iPS cells retained pluripotent cell characteristics for at least 20 passages. These data indicate that ATM does participate in the reprogramming process, although its role is not essential.

  6. Measuring Bystander Attitudes and Behavior to Prevent Sexual Violence

    Science.gov (United States)

    McMahon, Sarah; Allen, Christopher T.; Postmus, Judy L.; McMahon, Sheila M.; Peterson, N. Andrew; Lowe Hoffman, Melanie

    2014-01-01

    Objective: The purpose of this study is to further investigate the factor structure and strength of the Bystander Attitude Scale-Revised and Bystander Behavior Scale-Revised (BAS-R and BBS-R). Participants: First-year students (N = 4,054) at a large public university in the Northeast completed a survey in 2010 as part of a larger longitudinal…

  7. Lipids, atherosclerosis and CVD risk: is CRP an innocent bystander?

    DEFF Research Database (Denmark)

    Nordestgaard, B G; Zacho, J

    2009-01-01

    AIM: To evaluate recent human studies with respect to the interpretation of whether elevated plasma levels of C-reactive protein (CRP) cause cardiovascular disease (CVD), or whether elevated CRP levels more likely is an innocent bystander. DATA SYNTHESIS: Elevated CRP concentrations...... and vulnerability of atherosclerotic plaques, and thus simply an innocent bystander in CVD....

  8. The Bystander in Commercial Life : Obliged by Beneficence or Rescue

    NARCIS (Netherlands)

    Dubbink, Wim

    2016-01-01

    Liberalist thinking argues that moral agents have a right (or duty) to pursue an ordinary life. It also insists that moral agent can be bystanders. A bystander is involved with morally bad states of affairs in the sense that they are bound by moral duty, but for a non-blameworthy reason. A common

  9. Rape Myth Beliefs and Bystander Attitudes among Incoming College Students

    Science.gov (United States)

    McMahon, Sarah

    2010-01-01

    Objective: The bystander approach to rape prevention is gaining popularity on college campuses, although research is limited. This study explored bystander attitudes and their relationship with rape myths in a sample of college students. Participants: Surveys from 2,338 incoming undergraduate students at a large, northeastern university were…

  10. Bystander cells enhance NK cytotoxic efficiency by reducing search time.

    Science.gov (United States)

    Zhou, Xiao; Zhao, Renping; Schwarz, Karsten; Mangeat, Matthieu; Schwarz, Eva C; Hamed, Mohamed; Bogeski, Ivan; Helms, Volkhard; Rieger, Heiko; Qu, Bin

    2017-03-13

    Natural killer (NK) cells play a central role during innate immune responses by eliminating pathogen-infected or tumorigenic cells. In the microenvironment, NK cells encounter not only target cells but also other cell types including non-target bystander cells. The impact of bystander cells on NK killing efficiency is, however, still elusive. In this study we show that the presence of bystander cells, such as P815, monocytes or HUVEC, enhances NK killing efficiency. With bystander cells present, the velocity and persistence of NK cells were increased, whereas the degranulation of lytic granules remained unchanged. Bystander cell-derived H 2 O 2 was found to mediate the acceleration of NK cell migration. Using mathematical diffusion models, we confirm that local acceleration of NK cells in the vicinity of bystander cells reduces their search time to locate target cells. In addition, we found that integrin β chains (β1, β2 and β7) on NK cells are required for bystander-enhanced NK migration persistence. In conclusion, we show that acceleration of NK cell migration in the vicinity of H 2 O 2 -producing bystander cells reduces target cell search time and enhances NK killing efficiency.

  11. The bystander effect in an N-person dictator game

    NARCIS (Netherlands)

    Panchanathan, K.; Frankenhuis, W.E.; Silk, J.B.

    2013-01-01

    Dozens of studies show that bystanders are less likely to help victims as bystander number increases. However, these studies model one particular situation, in which victims need only one helper. Using a multi-player dictator game, we study a different but common situation, in which a recipient’s

  12. Bystander Approaches: Empowering Students to Model Ethical Sexual Behavior

    Science.gov (United States)

    Lynch, Annette; Fleming, Wm. Michael

    2005-01-01

    Sexual violence on college campuses is well documented. Prevention education has emerged as an alternative to victim-- and perpetrator--oriented approaches used in the past. One sexual violence prevention education approach focuses on educating and empowering the bystander to become a point of ethical intervention. In this model, bystanders to…

  13. The pursuit of the genome instability by comet assay (single cell gel electrophoresis) in patients with cancer of the cavum in western Algerian; La recherche de l'instabilite genomique par le test des cometes (single cell gel electrophoresis) chez les malades atteints d'un cancer du cavum dans l'Ouest algerien

    Energy Technology Data Exchange (ETDEWEB)

    Boukerche, A.; Dali-Youcef, A.F. [Service de Radiotherapie, Oran (Algeria); Bouali-Youcef, Y. [Laboratoire d' Immunologie, Oran (Algeria); Mehadji, M. [Service d' ORL, Oran (Algeria); Chenal, C. [Rennes-1 Univ., UMR CNRS 6853, 35 (France)

    2007-11-15

    The analysis of results has shown a constitutional genome instability among the patients with a cavum cancer with a defect in DNA repair where some exogenous factors ( Epstein-Barr virus, EBV) seem play an important part. (N.C.)

  14. When bystanders become bothersome : The negative consequences of bystander conflict and the moderating role of resilience

    NARCIS (Netherlands)

    van Erp, Kim J.P.M.; Rispens, Sonja; Gevers, Josette M.P.; Demerouti, Evangelia

    2015-01-01

    Bystander conflict is a situation in which employees are hindered in their work by parties not involved in the primary process. Public service employees and emergency care workers, such as ambulance employees and firefighters, often encounter this kind of conflict with potentially far-reaching

  15. When bystanders become bothersome : the negative consequences of bystander conflict and the moderating role of resilience

    NARCIS (Netherlands)

    van Erp, Kim; Rispens, Sonja; Gevers, Josette M.P.; Demerouti, Evangelia

    2014-01-01

    Bystander conflict is a situation in which employees are hindered in their work by parties not involved in the primary process. Public service employees and emergency care workers, such as ambulance employees and firefighters, often encounter this kind of conflict with potentially far-reaching

  16. The lonely bystander: ostracism leads to less helping in virtual bystander situations

    NARCIS (Netherlands)

    van Bommel, Marco; van Prooijen, Jan-Willem; Elffers, Henk; van Lange, Paul A.M.

    2016-01-01

    People are less likely to help when they have been ostracized, or when they are in the presence of bystanders. In the current manuscript we test both these influences simultaneously. We postulated two opposing hypotheses: first, helping decreases after ostracism, even when intervention is already

  17. Non-targeted bystander effects induced by ionizing radiation

    International Nuclear Information System (INIS)

    Morgan, William F.; Sowa, Marianne B.

    2007-01-01

    Radiation-induced bystander effects refer to those responses occurring in cells that were not subject to energy deposition events following ionizing radiation. These bystander cells may have been neighbors of irradiated cells, or physically separated but subject to soluble secreted signals from irradiated cells. Bystander effects have been observed in vitro and in vivo and for various radiation qualities. In tribute to an old friend and colleague, Anthony V. Carrano, who would have said 'well what are the critical questions that should be addressed, and so what?', we review the evidence for non-targeted radiation-induced bystander effects with emphasis on prevailing questions in this rapidly developing research field, and the potential significance of bystander effects in evaluating the detrimental health effects of radiation exposure

  18. The Bystander-Effect: A Meta-Analytic Review on Bystander Intervention in Dangerous and Non-Dangerous Emergencies

    Science.gov (United States)

    Fischer, Peter; Krueger, Joachim I.; Greitemeyer, Tobias; Vogrincic, Claudia; Kastenmuller, Andreas; Frey, Dieter; Heene, Moritz; Wicher, Magdalena; Kainbacher, Martina

    2011-01-01

    Research on bystander intervention has produced a great number of studies showing that the presence of other people in a critical situation reduces the likelihood that an individual will help. As the last systematic review of bystander research was published in 1981 and was not a quantitative meta-analysis in the modern sense, the present…

  19. Genomes

    National Research Council Canada - National Science Library

    Brown, T. A. (Terence A.)

    2002-01-01

    ... of genome expression and replication processes, and transcriptomics and proteomics. This text is richly illustrated with clear, easy-to-follow, full color diagrams, which are downloadable from the book's website...

  20. Enteropathogenic Escherichia coli: foe or innocent bystander?

    Science.gov (United States)

    Hu, Jia; Torres, Alfredo G.

    2015-01-01

    Enteropathogenic Escherichia coli (EPEC) remain one the most important pathogens infecting children and they are one of the main causes of persistent diarrhea worldwide. Historically, typical EPEC (tEPEC), defined as those isolates with the attaching and effacement (A/E) genotype (eae+), which possess bfpA+ and lack the stx- genes are found strongly associated with diarrheal cases. However, occurrence of atypical EPEC (aEPEC; eae+ bfpA- stx-) in diarrheal and asymptomatic hosts has made investigators question the role of these pathogens in human disease. Current epidemiological data is helping answering the question whether EPEC is mainly a foe or an innocent bystander during infection. PMID:25726041

  1. Genomic instability related to zinc deficiency and excess in an in vitro model: is the upper estimate of the physiological requirements recommended for children safe?

    Science.gov (United States)

    Padula, Gisel; Ponzinibbio, María Virginia; Gambaro, Rocío Celeste; Seoane, Analía Isabel

    2017-08-01

    Micronutrients are important for the prevention of degenerative diseases due to their role in maintaining genomic stability. Therefore, there is international concern about the need to redefine the optimal mineral and vitamin requirements to prevent DNA damage. We analyzed the cytostatic, cytotoxic, and genotoxic effect of in vitro zinc supplementation to determine the effects of zinc deficiency and excess and whether the upper estimate of the physiological requirement recommended for children is safe. To achieve zinc deficiency, DMEM/Ham's F12 medium (HF12) was chelated (HF12Q). Lymphocytes were isolated from healthy female donors (age range, 5-10 yr) and cultured for 7 d as follows: negative control (HF12, 60 μg/dl ZnSO 4 ); deficient (HF12Q, 12 μg/dl ZnSO 4 ); lower level (HF12Q + 80 μg/dl ZnSO 4 ); average level (HF12Q + 180 μg/dl ZnSO 4 ); upper limit (HF12Q + 280 μg/dl ZnSO 4 ); and excess (HF12Q + 380 μg/dl ZnSO 4 ). The comet (quantitative analysis) and cytokinesis-block micronucleus cytome assays were used. Differences were evaluated with Kruskal-Wallis and ANOVA (p < 0.05). Olive tail moment, tail length, micronuclei frequency, and apoptotic and necrotic percentages were significantly higher in the deficient, upper limit, and excess cultures compared with the negative control, lower, and average limit ones. In vitro zinc supplementation at the lower and average limit (80 and 180 μg/dl ZnSO 4 ) of the physiological requirement recommended for children proved to be the most beneficial in avoiding genomic instability, whereas the deficient, upper limit, and excess (12, 280, and 380 μg/dl) cultures increased DNA and chromosomal damage and apoptotic and necrotic frequencies.

  2. Regulation of early signaling and gene expression in the α-particle and bystander response of IMR-90 human fibroblasts

    Directory of Open Access Journals (Sweden)

    Hei Tom K

    2010-07-01

    Full Text Available Abstract Background The existence of a radiation bystander effect, in which non-irradiated cells respond to signals from irradiated cells, is well established. To understand early signaling and gene regulation in bystander cells, we used a bio-informatics approach, measuring global gene expression at 30 minutes and signaling pathways between 30 minutes and 4 hours after exposure to α-particles in IMR-90 fibroblasts. Methods We used whole human genome microarrays and real time quantitative PCR to measure and validate gene expression. Microarray analysis was done using BRB-Array Tools; pathway and ontology analyses were done using Ingenuity Pathway Analysis and PANTHER, respectively. We studied signaling in irradiated and bystander cells using immunoblotting and semi-quantitative image analysis. Results Gene ontology suggested signal transduction and transcriptional regulation responding 30 minutes after treatment affected cell structure, motility and adhesion, and interleukin synthesis. We measured time-dependent expression of genes controlled by the NF-κB pathway; matrix metalloproteinases 1 and 3; chemokine ligands 2, 3 and 5 and interleukins 1β, 6 and 33. There was an increased response of this set of genes 30 minutes after treatment and another wave of induction at 4 hours. We investigated AKT-GSK3β signaling and found both AKT and GSK3β are hyper-phosphorylated 30 minutes after irradiation and this effect is maintained through 4 hours. In bystander cells, a similar response was seen with a delay of 30 minutes. We proposed a network model where the observed decrease in phosphorylation of β-catenin protein after GSK3β dependent inactivation can trigger target gene expression at later times after radiation exposure Conclusions These results are the first to show that the radiation induced bystander signal induces a widespread gene expression response at 30 minutes after treatment and these changes are accompanied by modification of

  3. Radiation-induced bystander effects in vivo are sex specific

    International Nuclear Information System (INIS)

    Koturbash, Igor; Kutanzi, Kristy; Hendrickson, Karl; Rodriguez-Juarez, Rocio; Kogosov, Dmitry; Kovalchuk, Olga

    2008-01-01

    Ionizing radiation (IR) effects span beyond the area of direct exposure and can be observed in neighboring and distant naive cells and organs. This phenomenon is termed a 'bystander effect'. IR effects in directly exposed tissue in vivo are epigenetically mediated and distinct in males and females. Yet, IR-induced bystander effects have never been explored in a sex-specificity domain. We used an in vivo mouse model, whereby the bystander effects are studied in spleen of male and female animals subjected to head exposure when the rest of the body is protected by a medical-grade lead shield. We analyzed the induction of DNA damage and alterations in global DNA methylation. Molecular parameters were correlated with cellular proliferation and apoptosis levels. The changes observed in bystander organs are compared to the changes in unexposed animals and animals exposed to predicted and measured scatter doses. We have found the selective induction of DNA damage levels, global DNA methylation, cell proliferation and apoptosis in exposed and bystander spleen tissue of male and female mice. Sex differences were significantly diminished in animals subjected to a surgical removal of gonads. These data constitute the first evidence of sex differences in radiation-induced bystander effects in mouse spleen in vivo. We show the role of sex hormones in spleen bystander responses and discuss implications of the observed changes

  4. Radiation-induced bystander effects in vivo are sex specific

    Energy Technology Data Exchange (ETDEWEB)

    Koturbash, Igor; Kutanzi, Kristy; Hendrickson, Karl; Rodriguez-Juarez, Rocio; Kogosov, Dmitry [Department of Biological Sciences, University of Lethbridge, Alberta T1K 3M4 (Canada); Kovalchuk, Olga [Department of Biological Sciences, University of Lethbridge, Alberta T1K 3M4 (Canada)], E-mail: olga.kovalchuk@uleth.ca

    2008-07-03

    Ionizing radiation (IR) effects span beyond the area of direct exposure and can be observed in neighboring and distant naive cells and organs. This phenomenon is termed a 'bystander effect'. IR effects in directly exposed tissue in vivo are epigenetically mediated and distinct in males and females. Yet, IR-induced bystander effects have never been explored in a sex-specificity domain. We used an in vivo mouse model, whereby the bystander effects are studied in spleen of male and female animals subjected to head exposure when the rest of the body is protected by a medical-grade lead shield. We analyzed the induction of DNA damage and alterations in global DNA methylation. Molecular parameters were correlated with cellular proliferation and apoptosis levels. The changes observed in bystander organs are compared to the changes in unexposed animals and animals exposed to predicted and measured scatter doses. We have found the selective induction of DNA damage levels, global DNA methylation, cell proliferation and apoptosis in exposed and bystander spleen tissue of male and female mice. Sex differences were significantly diminished in animals subjected to a surgical removal of gonads. These data constitute the first evidence of sex differences in radiation-induced bystander effects in mouse spleen in vivo. We show the role of sex hormones in spleen bystander responses and discuss implications of the observed changes.

  5. Radiation-induced bystander effects in vivo are sex specific.

    Science.gov (United States)

    Koturbash, Igor; Kutanzi, Kristy; Hendrickson, Karl; Rodriguez-Juarez, Rocio; Kogosov, Dmitry; Kovalchuk, Olga

    2008-07-03

    Ionizing radiation (IR) effects span beyond the area of direct exposure and can be observed in neighboring and distant naïve cells and organs. This phenomenon is termed a 'bystander effect'. IR effects in directly exposed tissue in vivo are epigenetically mediated and distinct in males and females. Yet, IR-induced bystander effects have never been explored in a sex-specificity domain. We used an in vivo mouse model, whereby the bystander effects are studied in spleen of male and female animals subjected to head exposure when the rest of the body is protected by a medical-grade lead shield. We analyzed the induction of DNA damage and alterations in global DNA methylation. Molecular parameters were correlated with cellular proliferation and apoptosis levels. The changes observed in bystander organs are compared to the changes in unexposed animals and animals exposed to predicted and measured scatter doses. We have found the selective induction of DNA damage levels, global DNA methylation, cell proliferation and apoptosis in exposed and bystander spleen tissue of male and female mice. Sex differences were significantly diminished in animals subjected to a surgical removal of gonads. These data constitute the first evidence of sex differences in radiation-induced bystander effects in mouse spleen in vivo. We show the role of sex hormones in spleen bystander responses and discuss implications of the observed changes.

  6. Obstacles to bystander cardiopulmonary resuscitation in Japan.

    Science.gov (United States)

    Shibata, K; Taniguchi, T; Yoshida, M; Yamamoto, K

    2000-05-01

    bystander cardiopulmonary resuscitation (CPR) is performed infrequently in Japan. We conducted this study to identify Japanese attitudes toward the performance of bystander CPR. participants were asked about their willingness to perform CPR with varying scenarios and CPR techniques (mouth-to-mouth ventilation plus chest compression (MMV plus CC) versus chest compression alone (CC)). a total of 1302/1355 individuals completed the questionnaire, including high school students, teachers, emergency medical technicians, medical nurses, and medical students. About 2% of high school students, 3% of teachers, 26% of emergency medical technicians, 3% of medical nurses and 16% of medical students claimed they would 'definitely' perform MMV plus CC on a stranger. However, 21-72% claimed they would prefer the alternative of performing CC alone. Respondents claimed their unwillingness to perform MMV is not due to the fear of contracting a communicable disease, but the lack of confidence in their ability to perform CPR properly. in all categories of respondents, willingness to perform MMV plus CC for a stranger was disappointingly low. Better training in MMV together with teaching awareness that CC alone can be given should be instituted to maximize the number of potential providers of CPR in the community, even in communities where the incidence of HIV is very low.

  7. Genetic Signatures of HIV-1 Envelope-mediated Bystander Apoptosis

    Science.gov (United States)

    Joshi, Anjali; Lee, Raphael T. C.; Mohl, Jonathan; Sedano, Melina; Khong, Wei Xin; Ng, Oon Tek; Maurer-Stroh, Sebastian; Garg, Himanshu

    2014-01-01

    The envelope (Env) glycoprotein of HIV is an important determinant of viral pathogenesis. Several lines of evidence support the role of HIV-1 Env in inducing bystander apoptosis that may be a contributing factor in CD4+ T cell loss. However, most of the studies testing this phenomenon have been conducted with laboratory-adapted HIV-1 isolates. This raises the question of whether primary Envs derived from HIV-infected patients are capable of inducing bystander apoptosis and whether specific Env signatures are associated with this phenomenon. We developed a high throughput assay to determine the bystander apoptosis inducing activity of a panel of primary Envs. We tested 38 different Envs for bystander apoptosis, virion infectivity, neutralizing antibody sensitivity, and putative N-linked glycosylation sites along with a comprehensive sequence analysis to determine if specific sequence signatures within the viral Env are associated with bystander apoptosis. Our studies show that primary Envs vary considerably in their bystander apoptosis-inducing potential, a phenomenon that correlates inversely with putative N-linked glycosylation sites and positively with virion infectivity. By use of a novel phylogenetic analysis that avoids subtype bias coupled with structural considerations, we found specific residues like Arg-476 and Asn-425 that were associated with differences in bystander apoptosis induction. A specific role of these residues was also confirmed experimentally. These data demonstrate for the first time the potential of primary R5 Envs to mediate bystander apoptosis in CD4+ T cells. Furthermore, we identify specific genetic signatures within the Env that may be associated with the bystander apoptosis-inducing phenotype. PMID:24265318

  8. Bystander effect induced by ionizing radiation and its application

    International Nuclear Information System (INIS)

    Chen Feng; Tu Yu

    2009-01-01

    An indirect effect induced by ionizing radiation called bystander effect is being highly concentrated. Many domestic and foreign researchers have verified the existence of bystander effect and have got more understanding of the mechanism with advanced detection techniques and methods. So far, the research about it has expanded from a single cell to multiple cells, from the in vitro to the whole, and has extended to in vivo from in vitro, which provides powerful evidence to explain how bystander effects happen and the regulation mechanism and especially gives scientific evidence to clinical radiation oncology application in the future. (authors)

  9. Chromosomal instability induced by ionizing radiation

    International Nuclear Information System (INIS)

    Morgan, W.F.; Marder, B.A.; Day, J.P.

    1995-01-01

    There is accumulating evidence indicating genomic instability can manifest multiple generations after cellular exposure to DNA damaging agents. For instance, some cells surviving exposure to ionizing radiations show delayed reproductive cell death, delayed mutation and / or delayed chromosomal instability. Such instability, especially chromosome destabilization has been implicated in mutation, gene amplification, cellular transformation, and cell killing. To investigate chromosomal instability following DNA damage, we have used fluorescence in situ hybridization to detect chromosomal rearrangements in a human/hamster somatic hybrid cell line following exposure to ionizing radiation. Delayed chromosomal instability was detected when multiple populations of uniquely arranged metaphases were observed in clonal isolates raised from single cells. The relationship between delayed chromosomal destabilization and other endpoints of genomic instability, namely; delayed mutation and gene amplification will be discussed, as will the potential cytogenetic and molecular mechanisms contributing to delayed chromosomal instability

  10. Genomic Instability and Breast Cancer

    Science.gov (United States)

    2011-06-01

    distinguish these possibilities. The possible function of human SWI5-MEI5 in meiosis also needs to be investigated. It remains to be determined whether the... human SWI5-MEI5 complex acts in meiosis and, if it does, whether it acts with DMC1, RAD51, or both. Considering that SWI5-MEI5 is the only human ...tumorigenesis. This has been clearly illustrated in familial breast cancer, since human genetic studies reveal that many genes involved in DNA damage response

  11. Genome instability in Alzheimer disease

    DEFF Research Database (Denmark)

    Hou, Yujun; Song, Hyundong; Croteau, Deborah L

    2017-01-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia. Autosomal dominant, familial AD (fAD) is very rare and caused by mutations in amyloid precursor protein (APP), presenilin-1 (PSEN-1), and presenilin-2 (PSEN-2) genes. The pathogenesis...

  12. Are nonparticipants in prosocial behavior merely innocent bystanders?

    Science.gov (United States)

    Anker, Ashley E; Feeley, Thomas Hugh

    2011-01-01

    Latané and Darley's (1970) bystander intervention theory was used to model individuals' participation in two prosocial behaviors (organ donation, green living). It is argued that nonparticipants in prosocial helping are innocent bystanders who likely fail to notice the need, do not interpret the cause as an emergency, do not accept responsibility for the need to help, and have little knowledge on how to help. Data in study 1 (n = 494) indicate support for the proposed innocent bystander path model (notice event → interpret event as emergency → accept responsibility → knowledge of how to help) in organ donation. Study 2 (n = 519) replicated the model in the context of green living and additionally found a direct path from noticing the event to knowledge of how to help. Implications of framing nonparticipation in prosocial behaviors as innocent bystander effects are discussed in context of campaign communication.

  13. Caffeine Markedly Enhanced Radiation-Induced Bystander Effects

    International Nuclear Information System (INIS)

    Jiang Erkang; Wu Lijun

    2009-01-01

    In this paper it is shown that incubation with 2 mM caffeine enhanced significantly the MN (micronucleus) formation in both the 1 cGy α-particle irradiated and non-irradiated bystander regions. Moreover, caffeine treatment made the non-irradiated bystander cells more sensitive to damage signals. Treated by c-PTIO(2-(4-carboxy-phenyl)- 4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), a nitric oxide (NO) scavenger, the MN frequencies were effectively inhibited, showing that nitric oxide might be very important in mediating the enhanced damage. These results indicated that caffeine enhanced the low dose α-particle radiation-induced damage in irradiated and non-irradiated bystander regions, and therefore it is important to investigate the relationship between the radiosensitizer and radiation-induced bystander effects (RIBE). (ion beam bioengineering)

  14. DUOX 1 is induced in human thyroid cells submitted to X-Ray irradiation and is responsible for the bystander effect

    Energy Technology Data Exchange (ETDEWEB)

    Boufraqech, M.; Chevallier Lagente, O.; Weyemi, U.; Talbot, M.; Al Ghuzlan, A.; Courtin, F.; Bidart, J.M.; Schlumberger, M.; Dupuy, C. [UMR 8200 CNRS, Institut Gustave Roussy, Villejuit (France); Ameziane el Hassani, R. [UBRM, Centre National de l' Energie, des Sciences et des Techniques Nucleaires, Rabat (Morocco)

    2012-07-01

    Radiation-induced bystander effect is the mechanism by which cells that have not been directly exposed to ionizing radiation behave like exposed cells: they die or show chromosomal instability and other phenotypic abnormalities. Bystander cells may be either adjacent or at some distance from the exposed cells. Irradiated cells release soluble factors that can be transferred through cell culture medium to non-irradiated cells. These factors include cytokines and reactive oxygen species (ROS). The aim of this study was to identify the ROS generating system induced by X-ray irradiation of human thyroid cells that could be responsible for the bystander effect. Irradiation of human thyroid epithelial cells (HTori-3 cells) induced an extracellular production of H{sub 2}O{sub 2} after 4 days that was related to the radiation dose. Our study shows that radiation exposure increases DUOX-1 expression after several days, suggesting that this H{sub 2}O{sub 2} generating system could be responsible for the late bystander effect. This could have a potential importance for radiation risk assessment and for cancer radiotherapy

  15. ATR-dependent bystander effects in non-targeted cells

    International Nuclear Information System (INIS)

    Burdak-Rothkamm, S.

    2007-01-01

    Complete text of publication follows. Radiation induced non-targeted bystander effects have been reported for a range of endpoints including the induction of γH2AX foci which serve as a marker for DNA double strand breaks. We have recently reported the induction of γH2AX foci in non-targeted bystander cells up to 48 hours after irradiation and the involvement of reactive oxygen species (ROS) and TGF-beta 1 in the induction of γH2AX foci (Oncogene (2007) 26:993-1002). Here, we wanted to determine the role of the PI3-like kinases ATM, ATR and DNA-PK in DNA damage signalling in bystander cells. Conditioned medium from T98G cells irradiated with 2 Gy of X-rays was transferred onto non-irradiated cells that were subsequently analysed for the induction of γH2AX, ATR and 53BP1 foci as well as clonogenic survival. Irradiated T98G glioma cells generated signals that induced γH2AX and 53BP1 foci in cells treated with the conditioned medium from irradiated cells. These foci co-localised with ATR foci. Inhibition of ATM and DNA-PK could not suppress the induction of bystander γH2AX foci whereas the mutation of ATR in Seckel cells abrogated bystander foci induction. A restriction of bystander foci to the S-phase of the cell cycle both in T98G cells and in ATR- proficient fibroblasts was observed. These results identify ATR as a central player within the bystander signalling cascade leading to γH2AX and 53BP1 foci formation, and suggest a mechanism of DNA damage induction in non-targeted cells. Further investigations have shown decreased clonogenic cell survival in bystander T98G and ATR wild-type fibroblasts. ATR mutated Seckel cells and also ATM-/- fibroblasts were resistant to this effect suggesting a role for both ATR and ATM in the bystander signalling cascade with regard to cell survival. Taken together, these observations support a hypothesis of DNA damage-induced accumulation of stalled replication forks in bystander cells which are subsequently processed by

  16. Significance and nature of bystander responses induced by various agents.

    Science.gov (United States)

    Verma, Neha; Tiku, Ashu Bhan

    2017-07-01

    Bystander effects in a biological system are the responses shown by non-targeted neighbouring cells/tissues/organisms. These responses are triggered by factors released from targeted cells when exposed to a stress inducing agent. The biological response to stress inducing agents is complex, owing to the diversity of mechanisms and pathways activated in directly targeted and bystander cells. These responses are highly variable and can be either beneficial or hazardous depending on the cell lines tested, dose of agent used, experimental end points and time course selected. Recently non-targeted cells have even been reported to rescue the directly exposed cells by releasing protective signals that might be induced by non-targeted bystander responses. The nature of bystander signal/s is not yet clear. However, there are evidences suggesting involvement of ROS, RNS, protein factors and even DNA molecules leading to the activation of a number of signaling pathways. These can act independently or in a cascade, to induce events leading to changes in gene expression patterns that could elicit detrimental or beneficial effects. Many review articles on radiation induced bystander responses have been published. However, to the best of our knowledge, a comprehensive review on bystander responses induced by other genotoxic chemicals and stress inducing agents has not been published so far. Therefore, the aim of the present review is to give an overview of the literature on different aspects of bystander responses: agents that induce these responses, factors that can modulate bystander responses and the mechanisms involved. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Guidelines for Bystander First Aid 2016.

    Science.gov (United States)

    Pek, Jen Heng

    2017-07-01

    Cardiac life support is a form of first aid for cardiac emergencies. However, research and evidence in this field is lacking compared with other forms of first aid. Having identified the common emergencies that are encountered in the hospital, based on the available evidence, we have put together what could be an evidence-based approach to the first aid management of some of these common emergencies, viz. breathlessness, chest pain, allergies, stroke, heat injury, poisoning, unconsciousness, seizures, and trauma situations such as bleeding, wounds, contusions, head injury, burns and fractures. Educating the public is the key to developing a first responder bystander. These guidelines could become the basis for training of the public. Copyright: © Singapore Medical Association.

  18. Public Knowledge and Attitudes towards Bystander Cardiopulmonary Resuscitation in China

    Directory of Open Access Journals (Sweden)

    Meng Chen

    2017-01-01

    Full Text Available The rate of bystander CPR is much lower in China than in developed countries. This survey was implemented to assess the current status of layperson CPR training, to analyze the willingness of bystanders to perform CPR, and to identify barriers to improving bystander CPR rates. The questionnaire included individual information, current status of bystander CPR training, and individual’s willingness and attitude towards performing CPR. There were 25.6% laypersons who took CPR training. The majority (98.6% of laypersons would perform CPR on their family members, but fewer laypersons (76.3% were willing to perform CPR on strangers. Most respondents (53.2% were worried about legal issues. If laws were implemented to protect bystanders who give aid, the number of laypersons who were not willing to perform CPR on strangers dropped from 23.7% to 2.4%. An increasing number of people in China know CPR compared with the situation in the past. CPR training in China is much less common than in many developed countries. The barriers are that laypersons are not well-trained and they fear being prosecuted for unsuccessful CPR. More accredited CPR training courses are needed in China. The laws should be passed to protect bystanders who provide assistance.

  19. Significance of radiation-induced bystander effects in radiation therapy

    International Nuclear Information System (INIS)

    Suzuki, Masao

    2014-01-01

    Since 1994, a Phase I/II clinical study and radiotherapy have carried out using carbon-ion beams produced with the Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences. Now we constructed the new treatment facility for the advanced carbon-ion therapy at HIMAC applying a 3D fast spot scanning system with pencil beams. In the field of fundamental biological studies for high-LET heavy ions, there are some reports regarding bystander effects after exposure to alpha particles derived from 238 Pu or He-ion microbeams. However, only limited sets of studies have examined bystander effects after exposure to different ion species heavier than helium, such as carbon ions. We have been investigating bystander cellular responses in both normal human and human tumor cells irradiated with the HIMAC carbon ions. Bystander cell-killing effect was observed in the cells harboring wild-type P53 gene, but not in the P53-mutated cells. Moreover, observed bystander effect was suppressed by treating with a specific inhibitor of gap-junction mediated cell-cell communication. There is clear evidence that the carbon-ion irradiation enables the enhanced cell killing in cells with wild-type P53 gene via gap-junction mediated bystander effect. (author)

  20. The positive bystander effect: passive bystanders increase helping in situations with high expected negative consequences for the helper.

    Science.gov (United States)

    Fischer, Peter; Greitemeyer, Tobias

    2013-01-01

    The present field study investigated the interplay between the presence of a passive bystander (not present versus present) in a simulated bike theft and expected negative consequences (low versus high) in predicting intervention behavior when no physical victim is present. It was found that an additional bystander increases individual intervention in situations where the expected negative consequences for the helper in case of intervention were high (i.e., when the bike thief looks fierce) compared to situations where the expected negative consequences for the helper were low (i.e., when the bike thief does not look fierce). In contrast, no such effect for high vs. low expected negative consequences was observed when no additional bystander observed the critical situation. The results are discussed in light of previous laboratory findings on expected negative consequences and bystander intervention.

  1. Bystander effects and biota: implications of radiation-induced bystander effects for protection of the environment from ionising radiation

    International Nuclear Information System (INIS)

    Mothersill, C.E.; Seymour, C.B.

    2003-01-01

    Bystander effects are now known to be induced by both high and low LET in a variety of cells in culture. They have been proven to occur in vivo in mice following 0.5Gy total body irradiation and in blood from humans being treated for cancer by radiotherapy. Effects have also been detected in fish, crustacea and molluscs. The important questions now are not whether bystander effects occur but why and what implications they have, if any, for radiation protection. Different species and different genetic backgrounds within a species produce different types of bystander effect, different organs also produce different effects. This paper will review the data in this field and will discuss likely implications for protection of man and non-human biota. In particular it will look at the potential long-term outcomes for different organisational levels, from cell to ecosystem, of bystander mechanisms. In view of new concerns about the effects of low level radiation on non-human biota, emphasis will be placed on considering how bystander effects might operate at chronic low doses versus acute accidental low doses. Problems of radiation interaction with chemicals, whether chemicals can also induce 'bystander effects' , and how regulators might handle these situations which occur all the time in real environments, will be presented for discussion. Finally the paper will discuss likely implications of these mechanisms for evolutionary biology

  2. Carpal instability

    International Nuclear Information System (INIS)

    Schmitt, R.; Froehner, S.; Coblenz, G.; Christopoulos, G.

    2006-01-01

    This review addresses the pathoanatomical basics as well as the clinical and radiological presentation of instability patterns of the wrist. Carpal instability mostly follows an injury; however, other diseases, like CPPD arthropathy, can be associated. Instability occurs either if the carpus is unable to sustain physiologic loads (''dyskinetics'') or suffers from abnormal motion of its bones during movement (''dyskinematics''). In the classification of carpal instability, dissociative subcategories (located within proximal carpal row) are differentiated from non-dissociative subcategories (present between the carpal rows) and combined patterns. It is essential to note that the unstable wrist initially does not cause relevant signs in standard radiograms, therefore being ''occult'' for the radiologic assessment. This paper emphasizes the high utility of kinematographic studies, contrast-enhanced magnetic resonance imaging (MRI) and MR arthrography for detecting these predynamic and dynamic instability stages. Later in the natural history of carpal instability, static malalignment of the wrist and osteoarthritis will develop, both being associated with significant morbidity and disability. To prevent individual and socio-economic implications, the handsurgeon or orthopedist, as well as the radiologist, is challenged for early and precise diagnosis. (orig.)

  3. Delayed chromosomal instability induced by DNA damage

    International Nuclear Information System (INIS)

    Morgan, W.F.; Marder, B.A.; Day, J.P.

    1994-01-01

    Cellular exposure to DNA damaging agents rapidly results in a dose dependent increase in chromosomal breakage and gross structural chromosomal rearrangements. Over recent years, evidence has been accumulating indicating genomic instability can manifest multiple generations after cellular exposure to physical and chemical DNA damaging agents. Genomic instability manifests in the progeny of surviving cells, and has been implicated in mutation, gene application, cellular transformation, and cell killing. To investigate chromosome instability following DNA damage, we have used fluorescence in situ hybridization to detect chromosomal rearrangements in a human/hamster somatic hybrid cell line following exposure to ionizing radiation. Delayed chromosomal instability was detected when multiple populations of uniquely arranged metaphases were observed in clonal isolates raised from single cells surviving X-irradiation many generations after exposure. At higher radiation doses, chromosomal instability was observed in a relatively high frequency of surviving clones and, in general, those clones showed delayed chromosome instability also showed reduced survival as measured by colony forming ability

  4. Bystander effects: intercellular transmission of radiation damage signals

    Energy Technology Data Exchange (ETDEWEB)

    Little, J.B.; Azzam, E.I.; Toledo, S.M. de; Nagasawa, H

    2002-07-01

    Biological effects were examined in confluent cultures of fibroblasts and epithelial cells exposed to very low mean doses of alpha radiation, doses by which only 1-2% of the cells were actually traversed by an alpha particle. Enhanced frequencies of sister chromatid exchanges and HPRT mutations occurred in the non-irradiation, 'bystander' cells associated with a similar increase in the frequency of micronuclei, indicating the induction of DNA damage in these cells. In order to gain information concerning molecular pathways, changes in gene expression were examined in bystander cells by western analysis and in situ immunofluorescence staining. The expression levels of p53, p21 and MDM2 were significantly modulated in bystander cells: the damage signals leading to these changes were transmitted from irradiated to bystander cells by gap junction mediated intracellular communication. The bystander response was suppressed by incubation with superoxide dismutase as well as an inhibitor of NADPH oxidase, suggesting the effect may be mediated by oxidative stress. To examine other signalling pathways responsive to oxidative stress, the activation of stress-related kinases and their downstream transcription factors were analysed in bystander cells by western blotting and electrophoretic mobility shift assays: a 2-4 fold increase in the phosphorylation levels of JNK, EPK1/2, p90RSK, Elk-1 and ATF2 was observed. These changes were detected by 15 min after irradiation and persisted for at least 1 h. These findings indicate the activation of multiple signal transduction pathways in bystander cells, involving signals arising from the plasma membrane as well as from DNA damage. (author)

  5. Radioprotection of targeted and bystander cells by methylproamine

    International Nuclear Information System (INIS)

    Burdak-Rothkamm, Susanne; Smith, Andrea; Lobachevsky, Pavel; Martin, Roger; Prise, Kevin M.

    2015-01-01

    Radioprotective agents are of interest for application in radiotherapy for cancer and in public health medicine in the context of accidental radiation exposure. Methylproamine is the lead compound of a class of radioprotectors which act as DNA binding anti-oxidants, enabling the repair of transient radiation-induced oxidative DNA lesions. This study tested methylproamine for the radioprotection of both directly targeted and bystander cells. T98G glioma cells were treated with 15 μM methylproamine and exposed to 137 Cs γ-ray/X-ray irradiation and He 2+ microbeam irradiation. Radioprotection of directly targeted cells and bystander cells was measured by clonogenic survival or γH2AX assay. Radioprotection of directly targeted T98G cells by methylproamine was observed for 137 Cs γ-rays and X-rays but not for He 2+ charged particle irradiation. The effect of methylproamine on the bystander cell population was tested for both X-ray irradiation and He 2+ ion microbeam irradiation. The X-ray bystander experiments were carried out by medium transfer from irradiated to non-irradiated cultures and three experimental designs were tested. Radioprotection was only observed when recipient cells were pretreated with the drug prior to exposure to the conditioned medium. In microbeam bystander experiments targeted and nontargeted cells were co-cultured with continuous methylproamine treatment during irradiation and postradiation incubation; radioprotection of bystander cells was observed. Methylproamine protected targeted cells from DNA damage caused by γ-ray or X-ray radiation but not He 2+ ion radiation. Protection of bystander cells was independent of the type of radiation which the donor population received. (orig.) [de

  6. Radioprotection of targeted and bystander cells by methylproamine

    Energy Technology Data Exchange (ETDEWEB)

    Burdak-Rothkamm, Susanne [Queen' s University Belfast, Centre for Cancer Research and Cell Biology, Belfast (United Kingdom); Oxford University Hospitals, Cellular Pathology, Oxford (United Kingdom); Smith, Andrea; Lobachevsky, Pavel; Martin, Roger [Peter MacCallum Cancer Centre, Molecular Radiation Biology Laboratory, Melbourne (Australia); University of Melbourne, The Sir Peter MacCallum Department of Oncology, Melbourne (Australia); Prise, Kevin M. [Queen' s University Belfast, Centre for Cancer Research and Cell Biology, Belfast (United Kingdom)

    2014-09-23

    Radioprotective agents are of interest for application in radiotherapy for cancer and in public health medicine in the context of accidental radiation exposure. Methylproamine is the lead compound of a class of radioprotectors which act as DNA binding anti-oxidants, enabling the repair of transient radiation-induced oxidative DNA lesions. This study tested methylproamine for the radioprotection of both directly targeted and bystander cells. T98G glioma cells were treated with 15 μM methylproamine and exposed to {sup 137}Cs γ-ray/X-ray irradiation and He{sup 2+} microbeam irradiation. Radioprotection of directly targeted cells and bystander cells was measured by clonogenic survival or γH2AX assay. Radioprotection of directly targeted T98G cells by methylproamine was observed for {sup 137}Cs γ-rays and X-rays but not for He{sup 2+} charged particle irradiation. The effect of methylproamine on the bystander cell population was tested for both X-ray irradiation and He{sup 2+} ion microbeam irradiation. The X-ray bystander experiments were carried out by medium transfer from irradiated to non-irradiated cultures and three experimental designs were tested. Radioprotection was only observed when recipient cells were pretreated with the drug prior to exposure to the conditioned medium. In microbeam bystander experiments targeted and nontargeted cells were co-cultured with continuous methylproamine treatment during irradiation and postradiation incubation; radioprotection of bystander cells was observed. Methylproamine protected targeted cells from DNA damage caused by γ-ray or X-ray radiation but not He{sup 2+} ion radiation. Protection of bystander cells was independent of the type of radiation which the donor population received. (orig.) [German] Radioprotektive Agenzien sind sowohl in der Strahlentherapie von Krebserkrankungen als auch im Strahlenschutz im Zusammenhang mit akzidenteller Exposition von Bedeutung. Methylproamine ist die Leitsubstanz einer Klasse von

  7. Beyond the Situational Model: Bystander Action Consequences to Intervening in Situations Involving Sexual Violence.

    Science.gov (United States)

    Moschella, Elizabeth A; Bennett, Sidney; Banyard, Victoria L

    2016-03-02

    Sexual violence is a widely reported problem in college communities. To date, research has largely focused on bystander intervention as one way to help prevent this problem. Although perceived consequences of bystander intervention, such as the weighting of costs and benefits, have been examined, little research has explored what happens after a bystander intervenes. The current study investigated what bystanders report as perceived outcomes and actual consequences of their bystander actions in response to risk for sexual assault. Of the 545 surveyed, 150 reported having taking bystander action in the past month and qualitatively described their bystander behavior and the responses of those parties involved. A range of behavioral responses and intervention methods were identified. The most frequent responses reported by participants were victims conveying positive and perpetrators conveying negative responses. Different types of helping were associated with bystanders reporting different types of responses to their actions. Future research should incorporate additional measures of consequences of bystander intervention. Implications for policy and bystander intervention programs are discussed, stressing the need for bystander intervention programs to address a range of bystander behaviors and explain the potential consequences and risks of intervening. © The Author(s) 2016.

  8. A Randomized Controlled Trial of a Multi-Dose Bystander Intervention Program Using Peer Education Theater

    Science.gov (United States)

    McMahon, Sarah; Winter, Samantha C.; Palmer, Jane E.; Postmus, Judy L.; Peterson, N. Andrew; Zucker, Sharon; Koenick, RuthAnne

    2015-01-01

    This article reports findings from a longitudinal, experimental evaluation of a peer education theater program, Students Challenging Realities and Educating Against Myths (SCREAM) Theater. This study examines the impact of SCREAM Theater on a range of bystander-related outcomes (i.e. bystander intentions, bystander efficacy, perception of friend…

  9. Promoting Prosocial Behaviors to Prevent Dating Violence among College Students: Evaluation of a Bystander Intervention

    Science.gov (United States)

    Borsky, Amanda E.

    2014-01-01

    The objective of this dissertation was to evaluate a bystander behavior program at the Jefferson College of Health Sciences (JCHS) in Roanoke, Virginia. Specifically, this dissertation examined the: (1) preliminary measurement properties of a newly developed bystander behavior intention scale; (2) impact of the bystander intervention at JCHS; and…

  10. LGBT Discrimination on Campus and Heterosexual Bystanders: Understanding Intentions to Intervene

    Science.gov (United States)

    Dessel, Adrienne B.; Goodman, Kevin D.; Woodford, Michael R.

    2017-01-01

    Discrimination targeting lesbian, gay, bisexual, and transgender (LGBT) students on college campuses occurs. Bystander intervention is important in supporting targeted students and improving campus climate for LGBT students. Peer-familiarity context (i.e., who the bystander knows in the situation) can play a role in bystander intervention, but…

  11. Adolescent Bystander Behavior in the School and Online Environments and the Implications for Interventions Targeting Cyberbullying

    Science.gov (United States)

    Patterson, Lisa J.; Allan, Alfred; Cross, Donna

    2017-01-01

    The aim of this study was to add to the emerging knowledge about the role of bystanders in cyberbullying. To differentiate online versus offline bystander behaviors, 292 Australian children (mean age = 15.2; female = 54.4%) reviewed hypothetical scenarios experimentally manipulated by bystander sex, relationship to target and perpetrator, and…

  12. Nitric oxide mediated bystander responses induced by microbeam targeted cells

    International Nuclear Information System (INIS)

    Shao, C.; Prise, K.M.; Folkard, M.; Michael, B.D.

    2003-01-01

    Considerable evidence has recently been accumulated in support of the existence of a 'bystander effect', which cells having received no irradiation show biological consequences from their vicinal irradiated cells. The application of microbeams is providing new insights into the radiation-induced bystander effect. The present study found that when a fraction of radioresistant human glioblastoma cells were individually targeted with a precise number of helium ions generated from the Gray Cancer Institute Charged Particle Microbeam, micronucleus (MN) induction significantly exceeded the expected value that was calculated from the number of MN observed when all of the cells were targeted assuming no bystander effect occurring. Even when only a single cell within a population was hit by one helium ion, the MN induction in the population could be increased by 16%. These results provide direct evidence of radiation-induced bystander effect. Moreover, MN was effectively induced in the unirradiated primary human fibroblasts and glioblastoma cells either co-cultured with irradiated cells or treated with the medium harvested from irradiated cells, indicating a signal molecule was produced from the irradiated cells. However, when c-PTIO, a nitric oxide (NO)-specific scavenger, was present in the medium during and after irradiation until MN analysis, the production of MN in all of the above cases was reduced to low levels. Consequently, NO plays an important role in the radiation-induced bystander effect

  13. Radiation-Induced Bystander Response: Mechanism and Clinical Implications

    Science.gov (United States)

    Suzuki, Keiji; Yamashita, Shunichi

    2014-01-01

    Significance: Absorption of energy from ionizing radiation (IR) to the genetic material in the cell gives rise to damage to DNA in a dose-dependent manner. There are two types of DNA damage; by a high dose (causing acute or deterministic effects) and by a low dose (related to chronic or stochastic effects), both of which induce different health effects. Among radiation effects, acute cutaneous radiation syndrome results from cell killing as a consequence of high-dose exposure. Recent advances: Recent advances in radiation biology and oncology have demonstrated that bystander effects, which are emerged in cells that have never been exposed, but neighboring irradiated cells, are also involved in radiation effects. Bystander effects are now recognized as an indispensable component of tissue response related to deleterious effects of IR. Critical issues: Evidence has indicated that nonapoptotic premature senescence is commonly observed in various tissues and organs. Senesced cells were found to secrete various proteins, including cytokines, chemokines, and growth factors, most of which are equivalent to those identified as bystander factors. Secreted factors could trigger cell proliferation, angiogenesis, cell migration, inflammatory response, etc., which provide a tissue microenvironment assisting tissue repair and remodeling. Future directions: Understandings of the mechanisms and physiological relevance of radiation-induced bystander effects are quite essential for the beneficial control of wound healing and care. Further studies should extend our knowledge of the mechanisms of bystander effects and mode of cell death in response to IR. PMID:24761341

  14. Novel features of radiation-induced bystander signaling in Arabidopsis thaliana demonstrated using root micro-grafting

    Science.gov (United States)

    Wang, Ting; Li, Fanghua; Xu, Wei; Bian, Po; Wu, Yuejin; Wu, Lijun

    2012-01-01

    Radiation-induced bystander effects (RIBE) have been well demonstrated in whole organisms, as well as in single-cell culture models in vitro and multi-cellular tissues models in vitro, however, the underlying mechanisms remain unclear, including the temporal and spatial course of bystander signaling. The RIBE in vivo has been shown to exist in the model plant Arabidopsis thaliana (A. thaliana). Importantly, the unique plant grafting provides a delicate approach for studying the temporal and spatial course of bystander signaling in the context of whole plants. In our previous study, the time course of bystander signaling in plants has been well demonstrated using the root micro-grafting technique. In this study, we further investigated the temporal cooperation pattern of multiple bystander signals, the directionality of bystander signaling, and the effect of bystander tissues on the bystander signaling. The results showed that the bystander response could also be induced efficiently when the asynchronously generated bystander signals reached the bystander tissues in the same period, but not when they entered into the bystander tissues in an inversed sequence. The absence of bystander response in root-inversed grafting indicated that the bystander signaling along roots might be of directionality. The bystander signaling was shown to be independent of the bystander tissues. PMID:23072991

  15. Workplace mobbing: How the victim's coping behavior influences bystander responses.

    Science.gov (United States)

    Mulder, Roelie; Bos, Arjan E R; Pouwelse, Mieneke; van Dam, Karen

    2017-01-01

    Victims of workplace mobbing show diverse coping behavior. We investigated the impact of this behavior on bystander cognitions, emotions, and helping toward the victim, integrating coping literature with attribution theory. Adult part-time university students (N = 161) working at various organizations participated in a study with a 3(Coping: approach/avoidance/neutral) × 2(Gender Victim: male/female) × 2(Gender Bystander: male/female) design. Victims showing approach (vs. avoidance) coping were considered to be more self-reliant and less responsible for the continuation of the mobbing, and they elicited less anger. Continuation responsibility and self-reliance mediated the relationship between the victim's coping behavior and bystanders' helping intentions. Female (vs. male) participants reported more sympathy for the victim and greater willingness to help, and female (vs. male) victims elicited less anger. Theoretical and practical implications of the findings are discussed.

  16. Ionizing radiation-induced bystander mutagenesis and adaptation: Quantitative and temporal aspects

    International Nuclear Information System (INIS)

    Zhang Ying; Zhou Junqing; Baldwin, Joseph; Held, Kathryn D.; Prise, Kevin M.; Redmond, Robert W.; Liber, Howard L.

    2009-01-01

    This work explores several quantitative aspects of radiation-induced bystander mutagenesis in WTK1 human lymphoblast cells. Gamma-irradiation of cells was used to generate conditioned medium containing bystander signals, and that medium was transferred onto naive recipient cells. Kinetic studies revealed that it required up to 1 h to generate sufficient signal to induce the maximal level of mutations at the thymidine kinase locus in the bystander cells receiving the conditioned medium. Furthermore, it required at least 1 h of exposure to the signal in the bystander cells to induce mutations. Bystander signal was fairly stable in the medium, requiring 12-24 h to diminish. Medium that contained bystander signal was rendered ineffective by a 4-fold dilution; in contrast a greater than 20-fold decrease in the cell number irradiated to generate a bystander signal was needed to eliminate bystander-induced mutagenesis. This suggested some sort of feedback inhibition by bystander signal that prevented the signaling cells from releasing more signal. Finally, an ionizing radiation-induced adaptive response was shown to be effective in reducing bystander mutagenesis; in addition, low levels of exposure to bystander signal in the transferred medium induced adaptation that was effective in reducing mutations induced by subsequent γ-ray exposures.

  17. Bystander Effects During Synchrotron Imaging Procedures?

    International Nuclear Information System (INIS)

    Schueltke, Elisabeth; Nikkhah, Guido; Bewer, Brian; Wysokinski, Tomasz; Chapman, Dean

    2010-01-01

    Using monochromatic beam and synchrotron phase-contrast technique at the biomedical beamline of the Italian synchrotron facility Elettra (SYRMEP), we have shown in a small animal model of malignant brain tumor that it is possible to obtain high-resolution images of very small tumors when they have developed from implanted tumor cells loaded with colloidal gold nanoparticles (GNP). All previous experiments were conducted in post-mortem samples. We have now designed a cell culture experiment to investigate the effects of synchrotron radiation with an energy and dose profile similar to that expected in our first in vivo imaging studies according to the protocol developed at SYRMEP.Materials and Methods: Culture flasks containing either gold-loaded or naieve C6 glioma cells were exposed to a dose of 0.5 Gy at 24 keV. The irradiated medium was aspirated and replaced with fresh growth medium. Twenty-four hours later this non-irradiated medium exposed to irradiated cells was aspirated, then added to non-irradiated C6 cells in order to investigate whether bystander effects are seen under the conditions of our image acquisition protocol. The irradiated medium was added to a number of other non-irradiated cell cultures. Cell counts were followed until 72 hrs after irradiation. Western blots were conducted with H2AX antibodies. This experiment was one of the first biomedical experiments conducted at BMIT, the new biomedical imaging and therapy beamline of the Canadian Light Source.Results: No significant differences in proliferation were seen between cells that were directly irradiated, exposed to irradiated medium or exposed to the non-irradiated 24-hr-medium from the irradiated cells. However, there was a tendency towards a higher number of double strand breaks in previously irradiated cells when they were exposed to non-irradiated medium that had been in contact with irradiated cells for 24 hrs.

  18. Bystander defibrillation for out-of-hospital cardiac arrest in Public vs Residential Locations

    DEFF Research Database (Denmark)

    Hansen, Steen Møller; Hansen, Carolina Malta; Folke, Fredrik

    2017-01-01

    Importance: Bystander-delivered defibrillation (hereinafter referred to as bystander defibrillation) of patients with out-of-hospital cardiac arrests (OHCAs) remains limited despite the widespread dissemination of automated external defibrillators (AEDs). Objective: To examine calendar changes...... in bystander defibrillation and subsequent survival according to a public or a residential location of the cardiac arrest after nationwide initiatives in Denmark to facilitate bystander-mediated resuscitative efforts, including bystander defibrillation. Design, Setting, and Participants: This nationwide study......, 2016. Exposures: Nationwide initiatives to facilitate bystander resuscitative efforts, including bystander defibrillation, consisted of resuscitation training of Danish citizens, dissemination of on-site AEDs, foundation of an AED registry linked to emergency medical dispatch centers, and dispatcher...

  19. Mechanism of bystander-blaming: defensive attribution, counterfactual thinking, and gender.

    Science.gov (United States)

    Levy, Inna; Ben-David, Sarah

    2015-01-01

    Contemporary victimology recognizes that an understanding of the mechanism of blaming requires a comprehensive approach that includes the victim, the offender, and the bystander. However, most of the existing research on blaming focuses on the victim and the offender, ignoring the issue of bystander-blaming. This study highlights the bystander and investigates bystander-blaming by exploring some theoretical explanations, including counterfactual thinking, defensive attribution, and gender differences. The study included 363 young male and female participants, who read vignettes describing the behavior of the victim and the bystander in a rape scenario and answered questions regarding bystander-blaming. The results show that both counterfactual thinking and defensive attribution play a role in bystander-blaming. This article addresses the theoretical and practical implications of these findings. © The Author(s) 2013.

  20. Predicting Improvement After a Bystander Program for the Prevention of Sexual and Dating Violence.

    Science.gov (United States)

    Hines, Denise A; Palm Reed, Kathleen M

    2015-07-01

    Although evidence suggests that bystander prevention programs are promising interventions for decreasing sexual violence and dating violence on college campuses, there have been no studies to date evaluating moderators of bystander program effectiveness. The current study evaluates whether different demographic characteristics, attitudes, knowledge, and behaviors at pretest predict change over a 6-month follow-up for students who participated in a bystander prevention program. Participants in the three assessments (pretest, posttest, 6-month follow-up) included 296 college students who were mandated to attend a bystander program during their first year orientation. Analyses showed that with few exceptions, the bystander program worked best for students who were most at risk given their pretest demographics and levels of attitudes condoning dating violence and sexual violence, bystander efficacy, and bystander behaviors. Results are discussed in terms of suggestions for future research. © 2014 Society for Public Health Education.

  1. Commensal bacteria drive endogenous transformation and tumour stem cell marker expression through a bystander effect.

    Science.gov (United States)

    Wang, Xingmin; Yang, Yonghong; Huycke, Mark M

    2015-03-01

    Commensal bacteria and innate immunity play a major role in the development of colorectal cancer (CRC). We propose that selected commensals polarise colon macrophages to produce endogenous mutagens that initiate chromosomal instability (CIN), lead to expression of progenitor and tumour stem cell markers, and drive CRC through a bystander effect. Primary murine colon epithelial cells were repetitively exposed to Enterococcus faecalis-infected macrophages, or purified trans-4-hydroxy-2-nonenal (4-HNE)-an endogenous mutagen and spindle poison produced by macrophages. CIN, gene expression, growth as allografts in immunodeficient mice were examined for clones and expression of markers confirmed using interleukin (IL) 10 knockout mice colonised by E. faecalis. Primary colon epithelial cells exposed to polarised macrophages or 4-hydroxy-2-nonenal developed CIN and were transformed after 10 weekly treatments. In immunodeficient mice, 8 of 25 transformed clones grew as poorly differentiated carcinomas with 3 tumours invading skin and/or muscle. All tumours stained for cytokeratins confirming their epithelial cell origin. Gene expression profiling of clones showed alterations in 3 to 7 cancer driver genes per clone. Clones also strongly expressed stem/progenitor cell markers Ly6A and Ly6E. Although not differentially expressed in clones, murine allografts positively stained for the tumour stem cell marker doublecortin-like kinase 1. Doublecortin-like kinase 1 and Ly6A/E were expressed by epithelial cells in colon biopsies for areas of inflamed and dysplastic tissue from E. faecalis-colonised IL-10 knockout mice. These results validate a novel mechanism for CRC that involves endogenous CIN and cellular transformation arising through a microbiome-driven bystander effect. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  2. Radiation-induced chromosomal instability

    International Nuclear Information System (INIS)

    Ritter, S.

    1999-01-01

    Recent studies on radiation-induced chromosomal instability in the progeny of exposed mammalian cells were briefly described as well as other related studies. For the analysis of chromosomal damage in clones, cells were seeded directly after exposure in cell well-dish to form single cell clones and post-irradiation chromosome aberrations were scored. Both exposure to isoeffective doses of X-ray or 270 MeV/u C-ions (13 keV/μm) increased the number of clones with abnormal karyotype and the increase was similar for X-ray and for C-ions. Meanwhile, in the progeny of cells for mass cultures, there was no indication of a delayed expression of chromosomal damage up to 40 population doublings after the exposure. A high number of aberrant cells were only observed directly after exposure to 10.7 MeV/u O-ions, i.e. in the first cycle cells and decreased with subsequent cell divisions. The reason for these differences in the radiation-induced chromosomal instability between clonal isolates and mass culture has not been clarified. Recent studies indicated that genomic instability occurs at a high frequency in the progeny of cells irradiated with both sparsely and densely ionizing radiation. Such genomic instability is thought likely to increase the risk of carcinogenesis, but more data are required for a well understanding of the health risks resulting from radiation-induced delayed instability. (M.N.)

  3. Radiation-induced transgenerational instability.

    Science.gov (United States)

    Dubrova, Yuri E

    2003-10-13

    To date, the analysis of mutation induction has provided an irrefutable evidence for an elevated germline mutation rate in the parents directly exposed to ionizing radiation and a number of chemical mutagens. However, the results of numerous publications suggest that radiation may also have an indirect effect on genome stability, which is transmitted through the germ line of irradiated parents to their offspring. This review describes the phenomenon of transgenerational instability and focuses on the data showing increased cancer incidence and elevated mutation rates in the germ line and somatic tissues of the offspring of irradiated parents. The possible mechanisms of transgenerational instability are also discussed.

  4. Incoming College Students' Bystander Behaviors to Prevent Sexual Violence

    Science.gov (United States)

    McMahon, Sarah; Banyard, Victoria L.; McMahon, Sheila M.

    2015-01-01

    Evaluations of bystander intervention education programs demonstrate that this approach results in students' increased willingness to intervene in prosocial ways to prevent sexual violence (e.g., Moynihan, Banyard, Arnold, Eckstein, & Stapleton, 2010). These programs often focus on first-year college students, though theories and research on…

  5. A Qualitative Exploration of Cyber-Bystanders and Moral Engagement

    Science.gov (United States)

    Price, Deborah; Green, Deborah; Spears, Barbara; Scrimgeour, Margaret; Barnes, Alan; Geer, Ruth; Johnson, Bruce

    2014-01-01

    Studies have found that moral disengagement plays a significant role in the continuation of bullying situations (Bonanno, 2005); however, the moral stance of cyber-bystanders--those who witness online bullying--is not yet clear. While research into traditional face-to-face bullying reported that peers would probably or certainly intervene to…

  6. Delayed innocent bystander cell death following hypoxia in Caenorhabditis elegans.

    Science.gov (United States)

    Sun, C-L; Kim, E; Crowder, C M

    2014-04-01

    After hypoxia, cells may die immediately or have a protracted course, living or dying depending on an incompletely understood set of cell autonomous and nonautonomous factors. In stroke, for example, some neurons are thought to die from direct hypoxic injury by cell autonomous primary mechanisms, whereas other so called innocent bystander neurons die from factors released from the primarily injured cells. A major limitation in identifying these factors is the inability of current in vivo models to selectively target a set of cells for hypoxic injury so that the primarily injured cells and the innocent bystanders are clearly delineated. In order to develop such a model, we generated transgenic Caenorhabditis elegans strains where 2-3% of somatic cells were made selectively sensitive to hypoxia. This was accomplished by cell type-specific wild-type rescue in either pharyngeal myocytes or GABAergic neurons of a hypoxia resistance-producing translation factor mutation. Surprisingly, hypoxic targeting of these relatively small subsets of non-essential cells produced widespread innocent bystander cell injury, behavioral dysfunction and eventual organismal death. The hypoxic injury phenotypes of the myocyte or neuron sensitized strains were virtually identical. Using this model, we show that the C. elegans insulin receptor/FOXO transcription factor pathway improves survival when activated only after hypoxic injury and blocks innocent bystander death.

  7. Friends, strangers, and bystanders: Informal practices of sexual assault intervention.

    Science.gov (United States)

    Wamboldt, Alexander; Khan, Shamus R; Mellins, Claude Ann; Hirsch, Jennifer S

    2018-05-07

    Sexual assault is a part of many students' experiences in higher education. In U.S. universities, one in four women and one in ten men report being sexually assaulted before graduation. Bystander training programmes have been shown to modestly reduce campus sexual assault. Like all public health interventions, however, they have unintended social consequences; this research examines how undergraduate men on one campus understand bystander interventions and how those understandings shape their actual practices. We draw on ethnographic data collected between August 2015 and January 2017 at Columbia University and Barnard College. Our findings show that university training and an earnest desire to be responsible lead many men to intervene in possible sexual assaults. However, students' gendered methods target more socially vulnerable and socially distant men while protecting popular men and those to whom they are socially connected. Students' actual bystander practices thus reproduce social hierarchies in which low prestige may or may not be connected to actual risks of sexual assault. These results suggest that understanding intragroup dynamics and social hierarchies is essential to assault prevention in universities and that students' actions as bystanders may be effective at preventing assaults in some circumstances but may lead to new risks of sexual assault.

  8. Bystander Obligations at the Domestic and International Level Compared

    NARCIS (Netherlands)

    Spijkers, Otto|info:eu-repo/dai/nl/328454559

    2014-01-01

    This article examines whether States have a legal obligation to assist victims of serious breaches of fundamental obligations owed to the international community as a whole. This so-called ‘bystander State responsibility’ is compared with a similar legal obligation to assist victims at the domestic

  9. Bystander Reaction to Women Fighting: Developing a Theory of Intervention

    Science.gov (United States)

    Lowe, Robert D.; Levine, Mark; Best, Rachel M.; Heim, Derek

    2012-01-01

    This article explores accounts of bystanders to female-on-female public violence. Group interviews with participants in the night-time economy are carried out. Whereas men tend to respond to the discussion topic of female-on-female violence with laughter, this laughter reveals ambivalence and discomfort as much as amusement. Men seem to negotiate…

  10. Bystanders' Supportive and Passive Responses to Cyberaggression

    Science.gov (United States)

    Machackova, Hana; Dedkova, Lenka; Sevcikova, Anna; Cerna, Alena

    2018-01-01

    Bystanders in cyberaggression can support the victim, join the aggressor, or remain passive. We examined how supportive and passive adolescent Czech cyberbystanders (N = 443, ages 12-18) differ in terms of individual characteristics, emotional responses, and contextual factors. The most substantial distinguishing factor between the two groups…

  11. Reactive oxygen species and nitric oxide signaling in bystander cells.

    Science.gov (United States)

    Jella, Kishore Kumar; Moriarty, Roisin; McClean, Brendan; Byrne, Hugh J; Lyng, Fiona M

    2018-01-01

    It is now well accepted that radiation induced bystander effects can occur in cells exposed to media from irradiated cells. The aim of this study was to follow the bystander cells in real time following addition of media from irradiated cells and to determine the effect of inhibiting these signals. A human keratinocyte cell line, HaCaT cells, was irradiated (0.005, 0.05 and 0.5 Gy) with γ irradiation, conditioned medium was harvested after one hour and added to recipient bystander cells. Reactive oxygen species, nitric oxide, Glutathione levels, caspase activation, cytotoxicity and cell viability was measured after the addition of irradiated cell conditioned media to bystander cells. Reactive oxygen species and nitric oxide levels in bystander cells treated with 0.5Gy ICCM were analysed in real time using time lapse fluorescence microscopy. The levels of reactive oxygen species were also measured in real time after the addition of extracellular signal-regulated kinase and c-Jun amino-terminal kinase pathway inhibitors. ROS and glutathione levels were observed to increase after the addition of irradiated cell conditioned media (0.005, 0.05 and 0.5 Gy ICCM). Caspase activation was found to increase 4 hours after irradiated cell conditioned media treatment (0.005, 0.05 and 0.5 Gy ICCM) and this increase was observed up to 8 hours and there after a reduction in caspase activation was observed. A decrease in cell viability was observed but no major change in cytotoxicity was found in HaCaT cells after treatment with irradiated cell conditioned media (0.005, 0.05 and 0.5 Gy ICCM). This study involved the identification of key signaling molecules such as reactive oxygen species, nitric oxide, glutathione and caspases generated in bystander cells. These results suggest a clear connection between reactive oxygen species and cell survival pathways with persistent production of reactive oxygen species and nitric oxide in bystander cells following exposure to irradiated cell

  12. Investigations into the bystander effect: signal versus response

    International Nuclear Information System (INIS)

    Vines, A.M.; Seymour, C.B.; Mothersill, C.E.

    2003-01-01

    The bystander effect is the general term used to describe the effects seen in cells or tissue that have never been directly irradiated, but display similar symptoms to those that have. Some of these symptoms include reduced cell survival, chromosomal aberrations, and increased apoptosis. This investigation aims to explore the signal produced by certain cell and tissue types, and the relationship this has with the subsequent response. The goal is to elucidate whether the reduction in cell survival frequently seen in response to the bystander effect is determined by the signal produced or the response of the cell type. Firstly, a matrix design experiment was set up using 3 cell lines. Each cell line was irradiated to produce ICCM (Irradiated Cell Conditioned Medium), which was in turn used to treat all cell lines in the study. Medium transfer is carried out within cell lines, (ICCM from CHO onto CHO cells) and between cell lines (ICCM from CHO onto HPV-G cells). In the second set of experiments, tissue samples from male Wister rats were used to generate ITCM (Irradiated Tissue Conditioned Medium). This medium was then tested on a cell line with an established response to the bystander effect. As an extension to these two experimental protocols, both ICCM and ITCM were used to investigate if there is calcium flux in the cells as a response to the bystander medium. This has recently been shown to be an early response to the bystander signal. Results indicate that it is the signal produced by the irradiated cells that determine the overall effect of the bystander signal, and not the response of the cells expose to it. CHO-K1 cells treated with autologous ICCM show a 16.2% drop in cell survival. However, when this cell line is treated with HPV-G ICCM, it shows a 36.5% drop in survival. HPV-G cells treated with autologous medium display a similar response to this, with a 41.1% drop in survival, though when treated with CHO-K1 ICCM, the drop in survival is 22.9%. This

  13. Multi-College Bystander Intervention Evaluation for Violence Prevention.

    Science.gov (United States)

    Coker, Ann L; Bush, Heather M; Fisher, Bonnie S; Swan, Suzanne C; Williams, Corrine M; Clear, Emily R; DeGue, Sarah

    2016-03-01

    The 2013 Campus Sexual Violence Elimination Act requires U.S. colleges to provide bystander-based training to reduce sexual violence, but little is known about the efficacy of such programs for preventing violent behavior. This study provides the first multiyear evaluation of a bystander intervention's campus-level impact on reducing interpersonal violence victimization and perpetration behavior on college campuses. First-year students attending three similarly sized public university campuses were randomly selected and invited to complete online surveys in the spring terms of 2010-2013. On one campus, the Green Dot bystander intervention was implemented in 2008 (Intervention, n=2,979) and two comparison campuses had no bystander programming at baseline (Comparison, n=4,132). Data analyses conducted in 2014-2015 compared violence rates by condition over the four survey periods. Multivariable logistic regression was used to estimate violence risk on Intervention relative to Comparison campuses, adjusting for demographic factors and time (2010-2013). Interpersonal violence victimization rates (measured in the past academic year) were 17% lower among students attending the Intervention (46.4%) relative to Comparison (55.7%) campuses (adjusted rate ratio=0.83; 95% CI=0.79, 0.88); a similar pattern held for interpersonal violence perpetration (25.5% in Intervention; 32.2% in Comparison; adjusted rate ratio=0.79; 95% CI=0.71, 0.86). Violence rates were lower on Intervention versus Comparison campuses for unwanted sexual victimization, sexual harassment, stalking, and psychological dating violence victimization and perpetration (pSexual Violence Elimination Act bystander training requirements. Copyright © 2016 American Journal of Preventive Medicine. All rights reserved.

  14. Timely bystander CPR improves outcomes despite longer EMS times.

    Science.gov (United States)

    Park, Gwan Jin; Song, Kyoung Jun; Shin, Sang Do; Lee, Kyung Won; Ahn, Ki Ok; Lee, Eui Jung; Hong, Ki Jeong; Ro, Young Sun

    2017-08-01

    This study aimed to determine the impact of bystander CPR on clinical outcomes in patients with increasing response time from collapse to EMS response. A population-based observational study was conducted in patients with witnessed out-of-hospital cardiac arrest (OHCA) of presumed cardiac etiology from 2012 to 2014. The time interval from collapse to CPR by EMS providers was categorized into quartile groups: fastest group (bystander CPR and the time interval from collapse to CPR by EMS providers. A total of 15,354 OHCAs were analyzed. Bystander CPR was performed in 8591 (56.0%). Survival to hospital discharge occurred in 1632 (10.6%) and favorable neurological outcome in 996 (6.5%). In an interaction model of bystander CPR, compared to the fastest group, adjusted odds ratios (AORs) (95% CIs) for survival to discharge were 0.89 (0.66-1.20) in the fast group, 0.76 (0.57-1.02) in the late group, and 0.52 (0.37-0.73) in the latest group. For favorable neurological outcome, AORs were 1.12 (0.77-1.62) in the fast group, 0.90 (0.62-1.30) in the late group, 0.59 (0.38-0.91) in the latest group. The survival from OHCA decreases as the ambulance response time increases. The increase in mortality and worsening neurologic outcomes appear to be mitigated in those patients who receive bystander CPR. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Preventing Interpersonal Violence on College Campuses: The Effect of One Act Training on Bystander Intervention.

    Science.gov (United States)

    Alegría-Flores, Kei; Raker, Kelli; Pleasants, Robert K; Weaver, Mark A; Weinberger, Morris

    2015-05-22

    Sexual assault, stalking, dating violence, and intimate partner violence, herein collectively termed interpersonal violence (IV), are public health problems affecting 20% to 25% of female college students. Currently, One Act is one of the few IV prevention training programs at universities that teach students bystander skills to intervene in low- and high-risk IV situations. The objectives of this study were 1) to evaluate One Act's effects on date rape attitudes and behaviors, and bystanders' confidence, willingness to help, and behavior, and 2) to compare the effects on bystander skills between One Act and Helping Advocates for Violence Ending Now (HAVEN), an IV response training program with similar participants. Data were collected over 2 years, before and after One Act and HAVEN trainings. We measured outcomes with four scales: College Date Rape Attitudes and Behaviors, Bystander Confidence, Willingness to Help, and Bystander Behavior. The analysis compared within- and between-group mean differences in scale scores pre- and post-trainings using linear mixed models. One Act showed improvements for date rape attitudes and behaviors (p trainings' effects on bystander willingness to help and behavior had similar patterns but were not statistically significant. We found a larger positive impact on bystander confidence among students who participated in the bystander prevention training compared with the response training. Further research is needed to improve the measures for bystander behavior and measure the bystander trainings' larger impact on the community. © The Author(s) 2015.

  16. Predicting High-School Students' Bystander Behavior in Simulated Dating Violence Situations.

    Science.gov (United States)

    Jouriles, Ernest N; Rosenfield, David; Yule, Kristen; Sargent, Kelli S; McDonald, Renee

    2016-03-01

    Dating violence among adolescents is associated with a variety of negative health consequences for victims. Bystander programs are being developed and implemented with the intention of preventing such violence, but determinants of high-school students' responsive bystander behavior remain unclear. The present study examines hypothesized determinants of high-school students' bystander behavior in simulated situations of dating violence. Participants were 80 high-school students who completed self-reports of hypothesized determinants of bystander behavior (responsibility, efficacy, and perceived benefits for intervening) at a baseline assessment. A virtual-reality paradigm was used to observationally assess bystander behavior at 1-week and 6-month assessments after baseline. Efficacy for intervening was positively associated with observed bystander behavior at the 1-week and 6-month assessments. Moreover, efficacy predicted bystander behavior over and above feelings of responsibility and perceived benefits for intervening. Contrary to our predictions, neither responsibility nor perceived benefits for intervening were associated with observed bystander behavior. This research advances our understanding of determinants of bystander behavior for high-school students and can inform prevention programming for adolescents. The study also introduces an innovative way to assess high-school students' bystander behavior. Copyright © 2016 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

  17. Role of ROS-mediated autophagy in radiation-induced bystander effect of hepatoma cells.

    Science.gov (United States)

    Wang, Xiangdong; Zhang, Jianghong; Fu, Jiamei; Wang, Juan; Ye, Shuang; Liu, Weili; Shao, Chunlin

    2015-05-01

    Autophagy plays a crucial role in cellular response to ionizing radiation, but it is unclear whether autophagy can modulate radiation-induced bystander effect (RIBE). Here, we investigated the relationship between bystander damage and autophagy in human hepatoma cells of HepG2. HepG2 cells were treated with conditioned medium (CM) collected from 3 Gy γ-rays irradiated hepatoma HepG2 cells for 4, 12, or 24 h, followed by the measurement of micronuclei (MN), intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and protein expressions of microtubule-associated protein 1 light chain 3 (LC3) and Beclin-1 in the bystander HepG2 cells. In some experiments, the bystander HepG2 cells were respectively transfected with LC3 small interfering RNA (siRNA), Beclin-1 siRNA or treated with 1% dimethyl sulfoxide (DMSO). Additional MN and mitochondrial dysfunction coupled with ROS were induced in the bystander cells. The expressions of protein markers of autophagy, LC3-II/LC3-I and Beclin-1, increased in the bystander cells. The inductions of bystander MN and overexpressions of LC3 and Beclin-1 were significantly diminished by DMSO. However, when the bystander cells were transfected with LC3 siRNA or Beclin-1 siRNA, the yield of bystander MN was significantly enhanced. The elevated ROS have bi-functions in balancing the bystander effects. One is to cause MN and the other is to induce protective autophagy.

  18. Alpha-particles microbeam irradiation: impact of reactive oxygen species in bystander effect

    International Nuclear Information System (INIS)

    Hanot, M.

    2008-11-01

    Ionizing radiation-induced bystander effects arise in bystander cells that receive signals from directly irradiated cells. To date, free radicals are believed to play an active role in the bystander response, but this is incompletely characterized. To mark temporal and spatial impacts of bystander effect, we employed a precise α-particle microbeam to target a small fraction of sub-confluent osteoblastic cell cultures (MC3T3-E1). We identified the cellular membrane and mitochondria like two distinct places generating reactive oxygen species. The global oxidative stress observed after irradiation was significantly attenuated after filipin treatment, evidencing the pivotal role of membrane in MC3T3-E1 cells bystander response. To determine impact of bystander effect at a cell level, cellular consequences of this membrane-dependant bystander effect were then investigated. A variable fraction of the cell population (10 to 100%) was individually targeted. In this case, mitotic death and micronuclei yield both increased in bystander cells as well as in targeted cells demonstrating a role of bystander signals between irradiated cells in an autocrine or paracrine manner. Our results indicate a complex interaction of direct irradiation and bystander signals that lead to a membrane-dependant amplification of cell responses. (author)

  19. Bystander Interventions for Sexual Assault and Dating Violence on College Campuses: Are We Putting Bystanders in Harm's Way?

    Science.gov (United States)

    Witte, Tricia H.; Casper, Deborah M.; Hackman, Christine L.; Mulla, Mazheruddin M.

    2017-01-01

    Objective: The present study investigated the well-being of bystanders who witness and intervene in sexual assault and dating violence situations on campus. Participants: Participants were 321 young men and women from a large university in the southeastern United States. Methods: Participants completed a survey at the end of the Spring semester of…

  20. Hypervariable minisatellites: recombinators or innocent bystanders?

    Science.gov (United States)

    Jarman, A P; Wells, R A

    1989-11-01

    It has become apparent in recent years that unexpectedly large numbers of minisatellites exist within the eukaryotic genome. Their use in genetics is well known, but as with any new class of sequence, there is also much speculation about their involvement in a range of biological processes. How much is known of their biology?

  1. Self-protective function of post-conflict bystander affiliation in mandrills.

    Directory of Open Access Journals (Sweden)

    Gabriele Schino

    Full Text Available BACKGROUND: Affiliative interactions exchanged between victims of aggression and individuals not involved in the original aggression (bystanders have been observed in various species. Three hypothetical functions have been proposed for these interactions: consolation, self-protection and substitute reconciliation, but data to test them are scanty. METHODOLOGY/PRINCIPAL FINDINGS: We conducted post-conflict and matched control observations on a captive group of mandrills (Mandrillus sphinx. We found that victims often redirected aggression to bystanders, that they received most affiliation from those bystanders that were frequently the target of redirection, and that bystander affiliation reduced the likelihood of redirection. Bystander affiliation did not reduce the victim's distress (as measured by its scratching rates and was not received primarily from kin/friends. Finally, bystander affiliation did not reduce the likelihood of renewed aggression from the original aggressor. CONCLUSIONS/SIGNIFICANCE: These results provide support for the self-protection hypothesis but not for the consolation and substitute reconciliation hypotheses.

  2. Role of ATM in bystander signaling between human monocytes and lung adenocarcinoma cells.

    Science.gov (United States)

    Ghosh, Somnath; Ghosh, Anu; Krishna, Malini

    2015-12-01

    The response of a cell or tissue to ionizing radiation is mediated by direct damage to cellular components and indirect damage mediated by radiolysis of water. Radiation affects both irradiated cells and the surrounding cells and tissues. The radiation-induced bystander effect is defined by the presence of biological effects in cells that were not themselves in the field of irradiation. To establish the contribution of the bystander effect in the survival of the neighboring cells, lung carcinoma A549 cells were exposed to gamma-irradiation, 2Gy. The medium from the irradiated cells was transferred to non-irradiated A549 cells. Irradiated A549 cells as well as non-irradiated A549 cells cultured in the presence of medium from irradiated cells showed decrease in survival and increase in γ-H2AX and p-ATM foci, indicating a bystander effect. Bystander signaling was also observed between different cell types. Phorbol-12-myristate-13-acetate (PMA)-stimulated and gamma-irradiated U937 (human monocyte) cells induced a bystander response in non-irradiated A549 (lung carcinoma) cells as shown by decreased survival and increased γ-H2AX and p-ATM foci. Non-stimulated and/or irradiated U937 cells did not induce such effects in non-irradiated A549 cells. Since ATM protein was activated in irradiated cells as well as bystander cells, it was of interest to understand its role in bystander effect. Suppression of ATM with siRNA in A549 cells completely inhibited bystander effect in bystander A549 cells. On the other hand suppression of ATM with siRNA in PMA stimulated U937 cells caused only a partial inhibition of bystander effect in bystander A549 cells. These results indicate that apart from ATM, some additional factor may be involved in bystander effect between different cell types. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Mismatch repair genes Mlh1 and Mlh3 modify CAG instability in Huntington's disease mice: genome-wide and candidate approaches.

    Science.gov (United States)

    Pinto, Ricardo Mouro; Dragileva, Ella; Kirby, Andrew; Lloret, Alejandro; Lopez, Edith; St Claire, Jason; Panigrahi, Gagan B; Hou, Caixia; Holloway, Kim; Gillis, Tammy; Guide, Jolene R; Cohen, Paula E; Li, Guo-Min; Pearson, Christopher E; Daly, Mark J; Wheeler, Vanessa C

    2013-10-01

    The Huntington's disease gene (HTT) CAG repeat mutation undergoes somatic expansion that correlates with pathogenesis. Modifiers of somatic expansion may therefore provide routes for therapies targeting the underlying mutation, an approach that is likely applicable to other trinucleotide repeat diseases. Huntington's disease Hdh(Q111) mice exhibit higher levels of somatic HTT CAG expansion on a C57BL/6 genetic background (B6.Hdh(Q111) ) than on a 129 background (129.Hdh(Q111) ). Linkage mapping in (B6x129).Hdh(Q111) F2 intercross animals identified a single quantitative trait locus underlying the strain-specific difference in expansion in the striatum, implicating mismatch repair (MMR) gene Mlh1 as the most likely candidate modifier. Crossing B6.Hdh(Q111) mice onto an Mlh1 null background demonstrated that Mlh1 is essential for somatic CAG expansions and that it is an enhancer of nuclear huntingtin accumulation in striatal neurons. Hdh(Q111) somatic expansion was also abolished in mice deficient in the Mlh3 gene, implicating MutLγ (MLH1-MLH3) complex as a key driver of somatic expansion. Strikingly, Mlh1 and Mlh3 genes encoding MMR effector proteins were as critical to somatic expansion as Msh2 and Msh3 genes encoding DNA mismatch recognition complex MutSβ (MSH2-MSH3). The Mlh1 locus is highly polymorphic between B6 and 129 strains. While we were unable to detect any difference in base-base mismatch or short slipped-repeat repair activity between B6 and 129 MLH1 variants, repair efficiency was MLH1 dose-dependent. MLH1 mRNA and protein levels were significantly decreased in 129 mice compared to B6 mice, consistent with a dose-sensitive MLH1-dependent DNA repair mechanism underlying the somatic expansion difference between these strains. Together, these data identify Mlh1 and Mlh3 as novel critical genetic modifiers of HTT CAG instability, point to Mlh1 genetic variation as the likely source of the instability difference in B6 and 129 strains and suggest that MLH1

  4. Mismatch repair genes Mlh1 and Mlh3 modify CAG instability in Huntington's disease mice: genome-wide and candidate approaches.

    Directory of Open Access Journals (Sweden)

    Ricardo Mouro Pinto

    2013-10-01

    Full Text Available The Huntington's disease gene (HTT CAG repeat mutation undergoes somatic expansion that correlates with pathogenesis. Modifiers of somatic expansion may therefore provide routes for therapies targeting the underlying mutation, an approach that is likely applicable to other trinucleotide repeat diseases. Huntington's disease Hdh(Q111 mice exhibit higher levels of somatic HTT CAG expansion on a C57BL/6 genetic background (B6.Hdh(Q111 than on a 129 background (129.Hdh(Q111 . Linkage mapping in (B6x129.Hdh(Q111 F2 intercross animals identified a single quantitative trait locus underlying the strain-specific difference in expansion in the striatum, implicating mismatch repair (MMR gene Mlh1 as the most likely candidate modifier. Crossing B6.Hdh(Q111 mice onto an Mlh1 null background demonstrated that Mlh1 is essential for somatic CAG expansions and that it is an enhancer of nuclear huntingtin accumulation in striatal neurons. Hdh(Q111 somatic expansion was also abolished in mice deficient in the Mlh3 gene, implicating MutLγ (MLH1-MLH3 complex as a key driver of somatic expansion. Strikingly, Mlh1 and Mlh3 genes encoding MMR effector proteins were as critical to somatic expansion as Msh2 and Msh3 genes encoding DNA mismatch recognition complex MutSβ (MSH2-MSH3. The Mlh1 locus is highly polymorphic between B6 and 129 strains. While we were unable to detect any difference in base-base mismatch or short slipped-repeat repair activity between B6 and 129 MLH1 variants, repair efficiency was MLH1 dose-dependent. MLH1 mRNA and protein levels were significantly decreased in 129 mice compared to B6 mice, consistent with a dose-sensitive MLH1-dependent DNA repair mechanism underlying the somatic expansion difference between these strains. Together, these data identify Mlh1 and Mlh3 as novel critical genetic modifiers of HTT CAG instability, point to Mlh1 genetic variation as the likely source of the instability difference in B6 and 129 strains and suggest

  5. MiR-21 is involved in radiation-induced bystander effects

    Science.gov (United States)

    Xu, Shuai; Ding, Nan; Pei, Hailong; Hu, Wentao; Wei, Wenjun; Zhang, Xurui; Zhou, Guangming; Wang, Jufang

    2014-01-01

    Radiation-induced bystander effects are well-established phenomena, in which DNA damage responses are induced not only in the directly irradiated cells but also in the non-irradiated bystander cells through intercellular signal transmission. Recent studies hint that bystander effects are possibly mediated via small non-coding RNAs, especially microRNAs. Thus, more details about the roles of microRNA in bystander effects are urgently needed to be elucidated. Here we demonstrated that bystander effects were induced in human fetal lung MRC-5 fibroblasts through medium-mediated way by different types of radiation. We identified a set of differentially expressed microRNAs in the cell culture medium after irradiation, among which the up-regulation of miR-21 was further verified with qRT-PCR. In addition, we found significant upregulation of miR-21 in both directly irradiated cells and bystander cells, which was confirmed by the expression of miR-21 precursor and its target genes. Transfection of miR-21 mimics into non-irradiated MRC-5 cells caused bystander-like effects. Taken together, our data reveals that miR-21 is involved in radiation-induced bystander effects. Elucidation of such a miRNA-mediated bystander effect is of utmost importance in understanding the biological processes related to ionizing radiation and cell-to-cell communication. PMID:25483031

  6. Students as Prosocial Bystanders to Sexual Assault: Demographic Correlates of Intervention Norms, Intentions, and Missed Opportunities.

    Science.gov (United States)

    Hoxmeier, Jill C; Acock, Alan C; Flay, Brian R

    2017-01-01

    Sexual assault is a major public health issue. Bystander engagement programs are becoming widely used to combat sexual assault on college campuses. The purpose of this study was to examine students' intervention norms, intentions, opportunities, and behaviors as bystanders to sexual assault. Undergraduate students ( N = 779) completed the Sexual Assault Bystander Behavior Questionnaire in the fall of 2014. The t tests revealed differences in students' intervention norms, intentions, opportunities, and missed opportunities based on sex, race/ethnicity, athletic participation, and fraternity/sorority membership. The findings support the use of additional measures to assess bystander behavior and to identify student subpopulations that may benefit from programs aimed at increasing prosocial intervention.

  7. Influence of catechins on bystander responses in CHO cells induced by alpha-particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Law, Y.L.; Wong, T.P.W. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Yu, K.N. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)], E-mail: peter.yu@cityu.edu.hk

    2010-04-15

    In this work, we studied alpha-particle induced and medium-mediated bystander effects in Chinese hamster ovary (CHO) cells through micronucleus (MN) assay. We showed that signal transduction from irradiated cells to bystander cells occur within a short time after irradiation. We then studied the effects of ROS (reactive oxygen species)-scavenging catechins in the medium before irradiation. We observed decreases in the percentage of bystander cells with MN formation and thus proved the protection effect of catechins on bystander cells from radiation.

  8. Molecular subtypes in stage II-III colon cancer defined by genomic instability: early recurrence-risk associated with a high copy-number variation and loss of RUNX3 and CDKN2A.

    Directory of Open Access Journals (Sweden)

    Marianne Berg

    Full Text Available We sought to investigate various molecular subtypes defined by genomic instability that may be related to early death and recurrence in colon cancer.We sought to investigate various molecular subtypes defined by instability at microsatellites (MSI, changes in methylation patterns (CpG island methylator phenotype, CIMP or copy number variation (CNV in 8 genes. Stage II-III colon cancers (n = 64 were investigated by methylation-specific multiplex ligated probe amplification (MS-MLPA. Correlation of CNV, CIMP and MSI, with mutations in KRAS and BRAFV600E were assessed for overlap in molecular subtypes and early recurrence risk by uni- and multivariate regression.The CIMP phenotype occurred in 34% (22/64 and MSI in 27% (16/60 of the tumors, with noted CIMP/MSI overlap. Among the molecular subtypes, a high CNV phenotype had an associated odds ratio (OR for recurrence of 3.2 (95% CI 1.1-9.3; P = 0.026. Losses of CACNA1G (OR of 2.9, 95% CI 1.4-6.0; P = 0.001, IGF2 (OR of 4.3, 95% CI 1.1-15.8; P = 0.007, CDKN2A (p16 (OR of 2.0, 95% CI 1.1-3.6; P = 0.024, and RUNX3 (OR of 3.4, 95% CI 1.3-8.7; P = 0.002 were associated with early recurrence, while MSI, CIMP, KRAS or BRAF V600E mutations were not. The CNV was significantly higher in deceased patients (CNV in 6 of 8 compared to survivors (CNV in 3 of 8. Only stage and loss of RUNX3 and CDKN2A were significant in the multivariable risk-model for early recurrence.A high copy number variation phenotype is a strong predictor of early recurrence and death, and may indicate a dose-dependent relationship between genetic instability and outcome. Loss of tumor suppressors RUNX3 and CDKN2A were related to recurrence-risk and warrants further investigation.

  9. Bystander effects on mammalian cells induced by carbon ions

    International Nuclear Information System (INIS)

    Wang Jufang; Zhao Jing; Ma Qiufeng; Chinese Academy of Sciences, Beijing; Li Weijian; Zhou Guangming; Dang Bingrong; Mao Limin; Feng Yan

    2004-01-01

    Bystander effects on unirradiated V79 cells were observed by irradiated conditioned medium (ICM) method and co-cultured with carbon-ion-irradiated V79 cells. The results showed that the colony formation efficiency of unirradiated cells is obviously decreased by ICM. After co-culture with carbon-ion-irradiated cells for some time, the colony formation efficiency of co-cultured cells was lower than expected results assuming no bystander effects. The micronucleus frequency and hprt gene mutation rate was almost the same as expected results. Cytotoxic factor(s), which was effective for cell growth but not for micronucleus and mutation on unirradiated cells, might be released by irradiated cells. (authors)

  10. Attitudes toward the performance of bystander cardiopulmonary resuscitation in Japan.

    Science.gov (United States)

    Taniguchi, Takumi; Omi, Wataru; Inaba, Hideo

    2007-10-01

    Early initiation of bystander cardiopulmonary resuscitation (CPR) improves the chances of successful resuscitation and survival. The importance of bystander CPR is attracting more interest, and there has been an increase in attendance at CPR training courses in Japan. However, there have been few reports regarding Japanese attitudes toward the performance of bystander CPR. The present study was performed to identify current Japanese attitudes toward bystander CPR compared to our previous study performed in 1998. Between February and March 2006, participants were asked about their willingness to perform CPR in five varying scenarios, i.e., performing CPR on a stranger, a trauma patient, a child, an elderly person, and a relative, and CPR techniques consisting of chest compression plus mouth-to-mouth ventilation (CC plus MMV) versus chest compression only (CC only). A total of 4223 individuals (male 50%) completed the questionnaire, including high school students, teachers, emergency medical technicians (EMTs), medical nurses, and medical students. About 70% of the subjects had experienced CPR training more than once. Only 10-30% of high school students, teachers, and health care providers reported willingness to perform CC plus MMV, especially on a stranger or trauma victim. In contrast, 70-100% of these subjects reported willingness to perform CC only, which was the same as in our previous study. The reasons for the unwillingness among laypeople to perform CC plus MMV were inadequate knowledge and/or doubt regarding whether they could perform the techniques effectively, while health care providers reported a fear contracting of a disease. Most laypeople and health care providers are unlikely to perform CC plus MMV, especially on a stranger or trauma victim, but are more likely to perform CC only, as also found in our previous study in 1998. These findings suggest that MMV training should be de-emphasised and the awareness of CC alone should be emphasised because

  11. Cytokines shape chemotherapy-induced and 'bystander' senescence

    Czech Academy of Sciences Publication Activity Database

    Hodný, Zdeněk; Hubáčková, Soňa; Bartek, Jiří

    2010-01-01

    Roč. 2, č. 2 (2010), s. 375-376 ISSN 1945-4589 R&D Projects: GA ČR GA204/08/1418; GA ČR GA301/08/0353 Institutional research plan: CEZ:AV0Z50520514 Keywords : bystander cellular senescence * cytokines * PML Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.964, year: 2010

  12. Bystander Helping Behavior in Response to Workplace Bullying

    OpenAIRE

    Hellemans, Catherine; Dal Cason, Davide; Casini, Annalisa

    2017-01-01

    This research examines the role of colleagues in workplace bullying. While colleagues could often intervene to support the victim or stop the situation, passive behaviors and non-intervention are more frequent. The bystander effect highlighted by Latané and Darley (1970) has been studied in the context of school bullying and sexual harassment, but only rarely in the context of workplace bullying. We tested the impact of the belief in a just world for others, self-efficacy, perceived severity,...

  13. Host and Viral Factors in HIV-Mediated Bystander Apoptosis

    Science.gov (United States)

    Garg, Himanshu; Joshi, Anjali

    2017-01-01

    Human immunodeficiency virus (HIV) infections lead to a progressive loss of CD4 T cells primarily via the process of apoptosis. With a limited number of infected cells and vastly disproportionate apoptosis in HIV infected patients, it is believed that apoptosis of uninfected bystander cells plays a significant role in this process. Disease progression in HIV infected individuals is highly variable suggesting that both host and viral factors may influence HIV mediated apoptosis. Amongst the viral factors, the role of Envelope (Env) glycoprotein in bystander apoptosis is well documented. Recent evidence on the variability in apoptosis induction by primary patient derived Envs underscores the role of Env glycoprotein in HIV disease. Amongst the host factors, the role of C-C Chemokine Receptor type 5 (CCR5), a coreceptor for HIV Env, is also becoming increasingly evident. Polymorphisms in the CCR5 gene and promoter affect CCR5 cell surface expression and correlate with both apoptosis and CD4 loss. Finally, chronic immune activation in HIV infections induces multiple defects in the immune system and has recently been shown to accelerate HIV Env mediated CD4 apoptosis. Consequently, those factors that affect CCR5 expression and/or immune activation in turn indirectly regulate HIV mediated apoptosis making this phenomenon both complex and multifactorial. This review explores the complex role of various host and viral factors in determining HIV mediated bystander apoptosis. PMID:28829402

  14. Identifiable images of bystanders extracted from corneal reflections.

    Directory of Open Access Journals (Sweden)

    Rob Jenkins

    Full Text Available Criminal investigations often use photographic evidence to identify suspects. Here we combined robust face perception and high-resolution photography to mine face photographs for hidden information. By zooming in on high-resolution face photographs, we were able to recover images of unseen bystanders from reflections in the subjects' eyes. To establish whether these bystanders could be identified from the reflection images, we presented them as stimuli in a face matching task (Experiment 1. Accuracy in the face matching task was well above chance (50%, despite the unpromising source of the stimuli. Participants who were unfamiliar with the bystanders' faces (n = 16 performed at 71% accuracy [t(15 = 7.64, p<.0001, d = 1.91], and participants who were familiar with the faces (n = 16 performed at 84% accuracy [t(15 = 11.15, p<.0001, d = 2.79]. In a test of spontaneous recognition (Experiment 2, observers could reliably name a familiar face from an eye reflection image. For crimes in which the victims are photographed (e.g., hostage taking, child sex abuse, reflections in the eyes of the photographic subject could help to identify perpetrators.

  15. An investigation of bystander effects in Schizosaccharomyces pombe

    International Nuclear Information System (INIS)

    DeVeaux, L.C.; Wells, D.P.; Durtschi, L.S.; Reda, M.; Frujinoiu, C.; Harmon, F.

    2003-01-01

    Full text: 'Bystander' effects have been documented in various mammalian cell types and appear to act by two distinct mechanisms. One response requires a functional gap-junction. A non gap-junction-mediated response has also been observed in human cell lines, indicating release of a signaling factor. No analogous response has been investigated in unicellular organisms. Given that DNA damage signaling pathways are present in simple eukaryotes, we investigated bystander signaling effects using a single-celled organism, the fission yeast Schizosaccharomyces pombe. This organism may provide a much simpler model system than higher eukaryotic cells for studying these effects. We measured survival and mutation rate in an unirradiated culture after exposure to an irradiated culture. These two cultures were mixed immediately after irradiation, and any signaling factor that was produced had direct and continuous access to the unirradiated cells during subsequent cell divisions. The irradiated culture was from a multiply auxotrophic strain, whereas the unirradiated culture was from a prototrophic strain. Surviving colonies of the unirradiated culture were thus easily distinguished from those arising from irradiated cells. Mutation rates were measured as forward mutation to 2-deoxyglucose resistance. We have investigated bystander effects with electron and gamma dose from 6 to 20 MeV electron linacs. We varied electron beam energies, dose rates and temporal distributions of dose. The importance of this research stems from the fundamental evolutionary significance of cell signaling of any kind in unicellular systems, representing a major step toward the evolution of multi-cellular states

  16. Bystander Defibrillation for Out-of-Hospital Cardiac Arrest in Public vs Residential Locations.

    Science.gov (United States)

    Hansen, Steen Møller; Hansen, Carolina Malta; Folke, Fredrik; Rajan, Shahzleen; Kragholm, Kristian; Ejlskov, Linda; Gislason, Gunnar; Køber, Lars; Gerds, Thomas A; Hjortshøj, Søren; Lippert, Freddy; Torp-Pedersen, Christian; Wissenberg, Mads

    2017-05-01

    Bystander-delivered defibrillation (hereinafter referred to as bystander defibrillation) of patients with out-of-hospital cardiac arrests (OHCAs) remains limited despite the widespread dissemination of automated external defibrillators (AEDs). To examine calendar changes in bystander defibrillation and subsequent survival according to a public or a residential location of the cardiac arrest after nationwide initiatives in Denmark to facilitate bystander-mediated resuscitative efforts, including bystander defibrillation. This nationwide study identified 18 688 patients in Denmark with first-time OHCA from June 1, 2001, to December 31, 2012, using the Danish Cardiac Arrest Registry. Patients had a presumed cardiac cause of arrest that was not witnessed by emergency medical services personnel. Data were analyzed from April 1, 2015, to December 10, 2016. Nationwide initiatives to facilitate bystander resuscitative efforts, including bystander defibrillation, consisted of resuscitation training of Danish citizens, dissemination of on-site AEDs, foundation of an AED registry linked to emergency medical dispatch centers, and dispatcher-assisted guidance of bystander resuscitation efforts. The proportion of patients who received bystander defibrillation according to the location of the cardiac arrest and their subsequent 30-day survival. Of the 18 688 patients with OHCAs (67.8% men and 32.2% women; median [interquartile range] age, 72 [62-80] years), 4783 (25.6%) had a cardiac arrest in a public location and 13 905 (74.4%) in a residential location. The number of registered AEDs increased from 141 in 2007 to 7800 in 2012. The distribution of AED location was consistently skewed in favor of public locations. Bystander defibrillation increased in public locations from 3 of 245 (1.2%; 95% CI, 0.4%-3.5%) in 2001 to 78 of 510 (15.3%; 95% CI, 12.4%-18.7%) in 2012 (P bystander defibrillation increased in public locations from 8.3% (95% CI, 1.5%-35.4%) in 2001/2002 to 57

  17. Involvement of MAPK proteins in bystander effects induced by chemicals and ionizing radiation

    International Nuclear Information System (INIS)

    Asur, Rajalakshmi; Balasubramaniam, Mamtha; Marples, Brian; Thomas, Robert A.; Tucker, James D.

    2010-01-01

    Many studies have examined bystander effects induced by ionizing radiation, however few have evaluated the ability of chemicals to induce similar effects. We previously reported the ability of two chemicals, mitomycin C (MMC) and phleomycin (PHL) to induce bystander effects in normal human lymphoblastoid cell lines. The focus of the current study was to determine the involvement of the MAPK proteins in bystander effects induced by physical and chemical DNA damaging agents and to evaluate the effects of MAPK inhibition on bystander-induced caspase 3/7 activation. The phosphorylation levels of the MAPK proteins ERK1/2, JNK, and p38, were measured from 1 to 24 h following direct or bystander exposure to MMC, PHL or radiation. We observed transient phosphorylation, at early time points, of all 3 proteins in bystander cells. We also evaluated the effect of MAPK inhibition on bystander-induced caspase 3/7 activity to determine the role of MAPK proteins in bystander-induced apoptosis. We observed bystander-induced activation of caspase 3/7 in bystander cells. Inhibition of MAPK proteins resulted in a decrease in caspase 3/7 activity at the early time points, and the caspase activity increased (in the case of ERK inhibition) or returned to basal levels (in the case of JNK or p38 inhibition) between 12 and 24 h. PHL is considered to be a radiomimetic agent, however in the present study PHL behaved more like a chemical and not like radiation in terms of MAPK phosphorylation. These results point to the involvement of MAPK proteins in the bystander effect induced by radiation and chemicals and provide additional evidence that this response is not limited to radiation but is a generalized stress response in cells.

  18. Expression profiles are different in carbon ion-irradiated normal human fibroblasts and their bystander cells

    International Nuclear Information System (INIS)

    Iwakawa, Mayumi; Hamada, Nobuyuki; Imadome, Kaori; Funayama, Tomoo; Sakashita, Testuya; Kobayashi, Yasuhiko; Imai, Takashi

    2008-01-01

    Evidence has accumulated that ionizing radiation induces biological effects in non-irradiated bystander cells having received signals from directly irradiated cells; however, energetic heavy ion-induced bystander response is incompletely characterized. Here we performed microarray analysis of irradiated and bystander fibroblasts in confluent cultures. To see the effects in bystander cells, each of 1, 5 and 25 sites was targeted with 10 particles of carbon ions (18.3 MeV/u, 103 keV/μm) using microbeams, where particles traversed 0.00026, 0.0013 and 0.0066% of cells, respectively. diated cells, cultures were exposed to 10% survival dose (D), 0.1D and 0.01D of corresponding broadbeams (108 keV/μm). Irrespective of the target numbers (1, 5 or 25 sites) and the time (2 or 6 h postirradiation), similar expression changes were observed in bystander cells. Among 874 probes that showed more than 1.5-fold changes in bystander cells, 25% were upregulated and the remainder downregulated. These included genes related to cell communication (PIK3C2A, GNA13, FN1, ANXA1 and IL1RAP), stress response (RAD23B, ATF4 and EIF2AK4) and cell cycle (MYCN, RBBP4 and NEUROG1). Pathway analysis revealed serial bystander activation of G protein/PI-3 kinase pathways. Instead, genes related to cell cycle or death (CDKN1A, GADD45A, NOTCH1 and BCL2L1), and cell communication (IL1B, TCF7 and ID1) were upregulated in irradiated cells, but not in bystander cells. Our results indicate different expression profiles in irradiated and bystander cells, and imply that intercellular signaling between irradiated and bystander cells activate intracellular signaling, leading to the transcriptional stress response in bystander cells

  19. Radiation-induced bystander effects in cultured human stem cells.

    Directory of Open Access Journals (Sweden)

    Mykyta V Sokolov

    2010-12-01

    Full Text Available The radiation-induced "bystander effect" (RIBE was shown to occur in a number of experimental systems both in vitro and in vivo as a result of exposure to ionizing radiation (IR. RIBE manifests itself by intercellular communication from irradiated cells to non-irradiated cells which may cause DNA damage and eventual death in these bystander cells. It is known that human stem cells (hSC are ultimately involved in numerous crucial biological processes such as embryologic development; maintenance of normal homeostasis; aging; and aging-related pathologies such as cancerogenesis and other diseases. However, very little is known about radiation-induced bystander effect in hSC. To mechanistically interrogate RIBE responses and to gain novel insights into RIBE specifically in hSC compartment, both medium transfer and cell co-culture bystander protocols were employed.Human bone-marrow mesenchymal stem cells (hMSC and embryonic stem cells (hESC were irradiated with doses 0.2 Gy, 2 Gy and 10 Gy of X-rays, allowed to recover either for 1 hr or 24 hr. Then conditioned medium was collected and transferred to non-irradiated hSC for time course studies. In addition, irradiated hMSC were labeled with a vital CMRA dye and co-cultured with non-irradiated bystander hMSC. The medium transfer data showed no evidence for RIBE either in hMSC and hESC by the criteria of induction of DNA damage and for apoptotic cell death compared to non-irradiated cells (p>0.05. A lack of robust RIBE was also demonstrated in hMSC co-cultured with irradiated cells (p>0.05.These data indicate that hSC might not be susceptible to damaging effects of RIBE signaling compared to differentiated adult human somatic cells as shown previously. This finding could have profound implications in a field of radiation biology/oncology, in evaluating radiation risk of IR exposures, and for the safety and efficacy of hSC regenerative-based therapies.

  20. Vincristine-induced bystander effect in human lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Testi, Serena; Azzarà, Alessia; Giovannini, Caterina; Lombardi, Sara [Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa (Italy); Piaggi, Simona [Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Pisa University, Via Savi 10, 56126 Pisa (Italy); Facioni, Maria Sole [Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa (Italy); Scarpato, Roberto, E-mail: roberto.scarpato@unipi.it [Unità di Genetica, Dipartimento di Biologia, Pisa University, Via Derna 1, 56126 Pisa (Italy); Research Center of Nutraceuticals and Food for Health, University of Pisa, Pisa (Italy)

    2016-07-15

    Highlights: • We studied whether or not vincristine induced a bystander response in human lymphocytes. • Vincristine significantly increased MN frequencies in mononucleated recipient cells. • ROS or soluble proteins (IL-32 and TGF-β) may account for the observed response. - Abstract: Bystander effect is a known radiobiological effect, widely described using ionizing radiations and which, more recently, has also been related to chemical mutagens. In this study, we aimed to assess whether or not a bystander response can be induced in cultured human peripheral lymphocytes by vincristine, a chemotherapeutic mutagen acting as spindle poison, and by mitomycin-C, an alkylating agent already known to induce this response in human lymphoblastoid cells. Designing a modified ad hoc protocol for the cytokinesis blocked micronucleus (MN) assay, we detected the presence of a dose-dependent bystander response in untreated cultures receiving the conditioned medium (CM) from mitomycin-C (MMC) or vincristine (VCR) treated cultures. In the case of MMC, MN frequencies, expressed as micronucleated binucleates, were: 13.5 ± 1.41 at 6 μM, 22 ± 2.12 at 12 μM or 28.25 ± 5.13 at 15 μM vs. a control value of 4.75 ± 1.59. MN levels for VCR, expressed as micronucleated mononucleates were: 2.75 ± 0.88 at 0.0 μM, 27.25 ± 2.30 at 0.4 μM, 46.25 ± 1.94 at 0.8 μM, 98.25 ± 7.25 at 1.6 μM. To verify that no mutagen residual was transferred to recipient cultures together with the CM, we evaluated MN levels in cultures receiving the medium immediately after three washings following the chemical treatment (unconditioned medium). We further confirmed these results using a cell-mixing approach where untreated lymphocytes were co-cultured with donor cells treated with an effect-inducing dose of MMC or VCR. A distinct production pattern of both reactive oxygen species and soluble mediator proteins by treated cells may account for the differences observed in the manifestation of the

  1. Vincristine-induced bystander effect in human lymphocytes

    International Nuclear Information System (INIS)

    Testi, Serena; Azzarà, Alessia; Giovannini, Caterina; Lombardi, Sara; Piaggi, Simona; Facioni, Maria Sole; Scarpato, Roberto

    2016-01-01

    Highlights: • We studied whether or not vincristine induced a bystander response in human lymphocytes. • Vincristine significantly increased MN frequencies in mononucleated recipient cells. • ROS or soluble proteins (IL-32 and TGF-β) may account for the observed response. - Abstract: Bystander effect is a known radiobiological effect, widely described using ionizing radiations and which, more recently, has also been related to chemical mutagens. In this study, we aimed to assess whether or not a bystander response can be induced in cultured human peripheral lymphocytes by vincristine, a chemotherapeutic mutagen acting as spindle poison, and by mitomycin-C, an alkylating agent already known to induce this response in human lymphoblastoid cells. Designing a modified ad hoc protocol for the cytokinesis blocked micronucleus (MN) assay, we detected the presence of a dose-dependent bystander response in untreated cultures receiving the conditioned medium (CM) from mitomycin-C (MMC) or vincristine (VCR) treated cultures. In the case of MMC, MN frequencies, expressed as micronucleated binucleates, were: 13.5 ± 1.41 at 6 μM, 22 ± 2.12 at 12 μM or 28.25 ± 5.13 at 15 μM vs. a control value of 4.75 ± 1.59. MN levels for VCR, expressed as micronucleated mononucleates were: 2.75 ± 0.88 at 0.0 μM, 27.25 ± 2.30 at 0.4 μM, 46.25 ± 1.94 at 0.8 μM, 98.25 ± 7.25 at 1.6 μM. To verify that no mutagen residual was transferred to recipient cultures together with the CM, we evaluated MN levels in cultures receiving the medium immediately after three washings following the chemical treatment (unconditioned medium). We further confirmed these results using a cell-mixing approach where untreated lymphocytes were co-cultured with donor cells treated with an effect-inducing dose of MMC or VCR. A distinct production pattern of both reactive oxygen species and soluble mediator proteins by treated cells may account for the differences observed in the manifestation of the

  2. Do Sexual Assault Bystander Interventions Change Men's Intentions? Applying the Theory of Normative Social Behavior to Predicting Bystander Outcomes.

    Science.gov (United States)

    Mabry, Amanda; Turner, Monique Mitchell

    2016-01-01

    The high prevalence of sexual assault on college campuses has led to the implementation of health communication programs to prevent sexual assault. A few novel programs focus on primary prevention by targeting social norms related to gender and masculinity among men through bystander intervention. Guided by the theory of normative social behavior, this study sought to examine the relative effect of campaigns communicating positive versus negative injunctive norms and the interaction between exposure to such campaign messages and perceived descriptive norms and relevant cognitive moderators (e.g., outcome expectations, injunctive norms, group identity, ego involvement) among men. A 2 (high/low descriptive norms) × 2 (high/low moderator) × 3 (public service announcement) independent groups quasi-experimental design (N = 332) was used. Results indicated that messages communicating positive injunctive norms were most effective among men who were least likely to engage in bystander intervention. Furthermore, descriptive norms played a significant role in behavioral intentions, such that those with stronger norms were more likely to report intentions to engage in bystander behaviors in the future. Similarly, the moderators of aspiration, injunctive norms, social approval, and ego involvement had a significant positive effect on behavioral intentions. These findings have important implications for future message design strategy and audience segmentation.

  3. Conceptualizing the Engaging Bystander Approach to Sexual Violence Prevention on College Campuses

    Science.gov (United States)

    McMahon, Sarah; Postmus, Judy L.; Koenick, Ruth Anne

    2011-01-01

    Bystander intervention offers promise as a sexual violence prevention tool for student affairs administrators on college campuses, but the conceptualization and definition of the approach is in its infancy and needs further development. In an effort to emphasize the potential role of bystanders in the primary prevention of sexual violence, we put…

  4. Sorority Women's and Fraternity Men's Rape Myth Acceptance and Bystander Intervention Attitudes

    Science.gov (United States)

    Bannon, R. Sean; Brosi, Matthew W.; Foubert, John D.

    2013-01-01

    Sorority women and fraternity men are more likely than other students to be survivors and perpetrators of sexual assault, respectively. The present study examined sorority and fraternity members' rape myth acceptance, bystander efficacy, and bystander willingness to help in potential sexual assault situations. Sorority women were more rejecting of…

  5. Effects of a Rape Awareness Program on College Women: Increasing Bystander Efficacy and Willingness to Intervene

    Science.gov (United States)

    Foubert, John D.; Langhinrichsen-Rohling, Jennifer; Brasfield, Hope; Hill, Brent

    2010-01-01

    An experimental study evaluated the efficacy of a sexual assault risk-reduction program on 279 college women that focused on learning characteristics of male perpetrators and teaching bystander intervention techniques. After seeing The Women's Program, participants reported significantly greater bystander efficacy and significantly greater…

  6. Role of iNOS in Bystander Signaling Between Macrophages and Lymphoma Cells

    International Nuclear Information System (INIS)

    Ghosh, Somnath; Maurya, Dharmendra Kumar; Krishna, Malini

    2008-01-01

    Purpose: The present report describes the bystander effects of radiation between similar and dissimilar cells and the role of iNOS in such communication. Materials and Methods: EL-4 and RAW 264.7 cells were exposed to 5 Gy γ-irradiation. The medium from irradiated cells was transferred to unirradiated cells. Results: Irradiated EL-4 cells as well as those cultured in the presence of medium from γ-irradiated EL-4 cells showed an upregulation of NF-κB, iNOS, p53, and p21/waf1 genes. The directly irradiated and the bystander EL-4 cells showed an increase in DNA damage, apoptosis, and NO production. Bystander signaling was also found to exist between RAW 264.7 (macrophage) and EL-4 (lymphoma) cells. Unstimulated or irradiated RAW 264.7 cells did not induce bystander effect in unirradiated EL-4 cells, but LPS stimulated and irradiated RAW 264.7 cells induced an upregulation of NF-κB and iNOS genes and increased the DNA damage in bystander EL-4 cells. Treatment of EL-4 or RAW 264.7 cells with L-NAME significantly reduced the induction of gene expression and DNA damage in the bystander EL-4 cells, whereas treatment with cPTIO only partially reduced the induction of gene expression and DNA damage in the bystander EL-4 cells. Conclusions: It was concluded that active iNOS in the irradiated cells was essential for bystander response

  7. Engaging Upstanders: Class-Wide Approach to Promoting Positive Bystander Behavior

    Science.gov (United States)

    Wood, Laura; Smith, Jennifer; Varjas, Kris; Meyers, Joel

    2016-01-01

    Positive and supportive bystander behaviors have been associated with decreases in the frequency and negative impact of bullying. This article addresses the design, implementation, evaluation, and continuation of a classroom-based intervention that promotes positive bystander behaviors. The Engaging Upstanders curriculum was piloted with two…

  8. Effective suppression of bystander effects by DMSO treatment of irradiated CHO cells

    International Nuclear Information System (INIS)

    Kashino, Genro; Prise, K.M.; Suzuki, Keiji

    2007-01-01

    Evidence is accumulating that irradiated cells produce some signals which interact with non-exposed cells in the same population via a bystander effect. Here, we examined whether dimethyl sulfoxide (DMSO) is effective in suppressing radiation induced bystander effects in Chinese hamster ovary (CHO) and repair deficient xrs5 cells. When 1 Gy-irradiated CHO cells were treated with 0.5% DMSO for 1 hr before irradiation, the induction of micronuclei in irradiated cells was suppressed to 80% of that in non-treated irradiated cells. The suppressive effect of DMSO on the formation of bystander signals was examined and the results demonstrated that 0.5% DMSO treatment of irradiated cells completely suppressed the induction of micronuclei by the bystander effect in non-irradiated cells. It is suggested that irradiated cells ceased signal formation for bystander effects by the action of DMSO. To determine the involvement of reactive oxygen species on the formation of bystander signals, we examined oxidative stress levels using the 2',7'-dichlorofluorescein (DCFH) staining method in irradiated populations. The results showed that the treatment of irradiated cells with 0.5% DMSO did not suppress oxidative stress levels. These results suggest that the prevention of oxidative stress is independent of the suppressive effect of DMSO on the formation of the bystander signal in irradiated cells. It is suggested that increased reactive oxygen species (ROS) in irradiated cells is not a substantial trigger of a bystander signal. (author)

  9. Individual Motivations and Characteristics Associated with Bystander Intervention during Bullying Episodes among Children and Youth

    Science.gov (United States)

    Cappadocia, M. Catherine; Pepler, Debra; Cummings, Joanne G.; Craig, Wendy

    2012-01-01

    The aim of the current study was to explore bystander experiences during bullying episodes among children and youth attending a residential summer camp by investigating rates of witnessing and intervention, as well as individual motivations and characteristics associated with bystander intervention. The majority of children had witnessed bullying…

  10. What Would You Do? Strategies for Bystander Intervention to Prevent Sexual Violence by College Students

    Science.gov (United States)

    McMahon, Sarah; Hoffman, Melanie Lowe; McMahon, Sheila M.; Zucker, Sharon; Koenick, Ruth Anne

    2013-01-01

    Bystander education is an increasingly utilized strategy for addressing sexual assault prevention and intervention on U.S. college campuses. Given the paramount importance of peers among college students, what types of pro-social bystander interventions do students themselves deem feasible in the campus context? Drawing on self-reports from…

  11. Action Research Evaluation of Bystander Intervention Training Created by Munche, Stern, and O'Brien

    Science.gov (United States)

    Shiflet, Jacqueline H.

    2013-01-01

    This qualitative, appreciative inquiry study was an examination of bystander intervention as related to sexual assault in the military. The purpose of the study was to examine how military personnel and Department of Defense civilian employees reflecting diverse backgrounds perceived the effectiveness of bystander intervention training and sexual…

  12. Roles of Fatalism and Parental Support in the Relationship between Bullying Victimization and Bystander Behaviors

    Science.gov (United States)

    Li, Yiqiong; Chen, Peter Y.; Chen, Fu-Li; Wu, Wen-Chi

    2015-01-01

    This article examines how past bullied victims engage two types of bystander behaviors (defender and outsider) when they witness bullying situations.We also investigate if fatalism mediates the relationship between past victimization and two bystander behaviors. Finally, we test if parental support moderates the relationship between fatalism and…

  13. Booze, Bars, and Bystander Behavior: People Who Consumed Alcohol Help Faster in the Presence of Others

    NARCIS (Netherlands)

    van Bommel, Marco; van Prooijen, Jan-Willem; Elffers, Henk; van Lange, Paul A.M.

    2016-01-01

    People help each other less often and less quickly when bystanders are present. In this paper, we propose that alcohol consumption could attenuate or reverse this so-called bystander effect. Alcohol impairs people cognitively and perceptually, leading them to think less about the presence of others

  14. Quality of bystander cardiopulmonary resuscitation during real-life out-of-hospital cardiac arrest

    DEFF Research Database (Denmark)

    Gyllenborg, Tore; Granfeldt, Asger; Lippert, Freddy

    2017-01-01

    BACKGROUND: Cardiopulmonary resuscitation (CPR) can increase survival in out-of-hospital cardiac arrest (OHCA). However, little is known about bystander CPR quality in real-life OHCA. AIM: To describe bystander CPR quality based on automated external defibrillator (AED) CPR process data during OH...

  15. On Standby? A Comparison of Online and Offline Witnesses to Bullying and Their Bystander Behaviour

    Science.gov (United States)

    Quirk, Roslynn; Campbell, Marilyn

    2015-01-01

    Given their ubiquitous presence as witnesses to school-yard bullying, the role of the "bystander" has been studied extensively. The prevalence and behaviour of bystanders to "cyberbullying," however, is less understood. In an anonymous, school-based questionnaire, 716 secondary school students from South-East Queensland…

  16. Debriefing bystanders of out-of-hospital cardiac arrest is valuable.

    Science.gov (United States)

    Møller, Thea Palsgaard; Hansen, Carolina Malta; Fjordholt, Martin; Pedersen, Birgitte Dahl; Østergaard, Doris; Lippert, Freddy K

    2014-11-01

    To explore the concept of debriefing bystanders after participating in an out-of-hospital cardiac arrest resuscitation attempt including (1) bystanders' most commonly addressed reactions after participating in a resuscitation attempt when receiving debriefing from medical dispatchers; (2) their perception of effects of receiving debriefing and (3) bystanders' recommendations for a systematic debriefing concept. Qualitative study based on telephone debriefing to bystanders and interviews with bystanders who received debriefing. Data was analyzed using the phenomenological approach. Six themes emerged from analysis of debriefing audio files: (1) identification of OHCA; (2) emotional and perceptual experience with OHCA; (3) collaboration with healthcare professionals; (4) patients outcome; (5) coping with the experience and (6) general reflections. When evaluating the concept, bystanders expressed positive short term effect of receiving debriefing and a retention of this effect after two months. Recommendations for a future debriefing concept were given. Debriefing by emergency medical dispatchers to OHCA bystanders stimulates reflection, positively influencing the ability to cope with the emotional reactions and the cognitive perception of own performance and motivates improvement of CPR skills. Importantly, it increases confidence to provide CPR in the future. Implementation of telephone debriefing to bystanders at Emergency Medical Dispatch Centres is a low complexity and a low cost intervention though the logistic challenges have to be considered. Copyright © 2014 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  17. Liver irradiation causes distal bystander effects in the rat brain and affects animal behaviour.

    Science.gov (United States)

    Kovalchuk, Anna; Mychasiuk, Richelle; Muhammad, Arif; Hossain, Shakhawat; Ilnytskyy, Slava; Ghose, Abhijit; Kirkby, Charles; Ghasroddashti, Esmaeel; Kovalchuk, Olga; Kolb, Bryan

    2016-01-26

    Radiation therapy can not only produce effects on targeted organs, but can also influence shielded bystander organs, such as the brain in targeted liver irradiation. The brain is sensitive to radiation exposure, and irradiation causes significant neuro-cognitive deficits, including deficits in attention, concentration, memory, and executive and visuospatial functions. The mechanisms of their occurrence are not understood, although they may be related to the bystander effects.We analyzed the induction, mechanisms, and behavioural repercussions of bystander effects in the brain upon liver irradiation in a well-established rat model.Here, we show for the first time that bystander effects occur in the prefrontal cortex and hippocampus regions upon liver irradiation, where they manifest as altered gene expression and somewhat increased levels of γH2AX. We also report that bystander effects in the brain are associated with neuroanatomical and behavioural changes, and are more pronounced in females than in males.

  18. Getting angry matters: Going beyond perspective taking and empathic concern to understand bystanders' behavior in bullying.

    Science.gov (United States)

    Pozzoli, Tiziana; Gini, Gianluca; Thornberg, Robert

    2017-12-01

    The present study examined the relations between different empathic dimensions and bystanders' behavior in bullying. Specifically, the indirect effects of empathic concern and perspective taking via empathic anger on defending and passive bystanding were tested in a sample of Italian young adolescents (N = 398; M age  = 12 years, 3 months, 47.2% girls). Path analysis confirmed the direct and indirect effects, via empathic anger, of empathic concern and perspective taking on bystanders' behavior, with the exception of the direct association between perspective taking and passive bystanding that was not significant. Our findings suggest that considering empathic anger together with empathic concern and perspective taking could help researchers to better understand the links between empathic dispositions and bystanders' behavior in bullying. Copyright © 2017. Published by Elsevier Ltd.

  19. Temporally distinct response of irradiated normal human fibroblasts and their bystander cells to energetic heavy ions

    International Nuclear Information System (INIS)

    Hamada, Nobuyuki; Ni, Meinan; Funayama, Tomoo; Sakashita, Tetsuya; Kobayashi, Yasuhiko

    2008-01-01

    Ionizing radiation-induced bystander effects have been documented for a multitude of endpoints such as mutations, chromosome aberrations and cell death, which arise in nonirradiated bystander cells having received signals from directly irradiated cells; however, energetic heavy ion-induced bystander response is incompletely characterized. To address this, we employed precise microbeams of carbon and neon ions for targeting only a very small fraction of cells in confluent fibroblast cultures. Conventional broadfield irradiation was conducted in parallel to see the effects in irradiated cells. Exposure of 0.00026% of cells led to nearly 10% reductions in the clonogenic survival and twofold rises in the apoptotic incidence regardless of ion species. Whilst apoptotic frequency increased with time up to 72 h postirradiation in irradiated cells, its frequency escalated up to 24 h postirradiation but declined at 48 h postirradiation in bystander cells, indicating that bystander cells exhibit transient commitment to apoptosis. Carbon- and neon-ion microbeam irradiation similarly caused almost twofold increments in the levels of serine 15-phosphorylated p53 proteins, irrespective of whether 0.00026, 0.0013 or 0.0066% of cells were targeted. Whereas the levels of phosphorylated p53 were elevated and remained unchanged at 2 h and 6 h postirradiation in irradiated cells, its levels rose at 6 h postirradiation but not at 2 h postirradiation in bystander cells, suggesting that bystander cells manifest delayed p53 phosphorylation. Collectively, our results indicate that heavy ions inactivate clonogenic potential of bystander cells, and that the time course of the response to heavy ions differs between irradiated and bystander cells. These induced bystander responses could be a defensive mechanism that minimizes further expansion of aberrant cells

  20. A Role for Bioelectric Effects in the Induction of Bystander Signals by Ionizing Radiation?

    Science.gov (United States)

    Mothersill, C.; Moran, G.; McNeill, F.; Gow, M.D.; Denbeigh, J.; Prestwich, W.; Seymour, C.B.

    2007-01-01

    The induction of “bystander effects” i.e. effects in cells which have not received an ionizing radiation track, is now accepted but the mechanisms are not completely clear. Bystander effects following high and low LET radiation exposure are accepted but mechanisms are still not understood. There is some evidence for a physical component to the signal. This paper tests the hypothesis that bioelectric or biomagnetic phenomena are involved. Human immortalized skin keratinocytes and primary explants of mouse bladder and fish skin, were exposed directly to ionizing radiation or treated in a variety of bystander protocols. Exposure of cells was conducted by shielding one group of flasks using lead, to reduce the dose below the threshold of 2mGy 60Cobalt gamma rays established for the bystander effect. The endpoint for the bystander effect in the reporter system used was reduction in cloning efficiency (RCE). The magnitude of the RCE was similar in shielded and unshielded flasks. When cells were placed in a Faraday cage the magnitude of the RCE was less but not eliminated. The results suggest that liquid media or cell-cell contact transmission of bystander factors may be only part of the bystander mechanism. Bioelectric or bio magnetic fields may have a role to play. To test this further, cells were placed in a Magnetic Resonance Imaging (MRI) machine for 10min using a typical head scan protocol. This treatment also induced a bystander response. Apart from the obvious clinical relevance, the MRI results further suggest that bystander effects may be produced by non-ionizing exposures. It is concluded that bioelectric or magnetic effects may be involved in producing bystander signaling cascades commonly seen following ionizing radiation exposure. PMID:18648606

  1. Lay Bystanders' Perspectives on What Facilitates Cardiopulmonary Resuscitation and Use of Automated External Defibrillators in Real Cardiac Arrests

    DEFF Research Database (Denmark)

    Malta Hansen, Carolina; Rosenkranz, Simone Mørk; Folke, Fredrik

    2017-01-01

    factors encourage lay bystanders to initiate CPR and AED use in a cohort of bystanders previously trained in CPR techniques who were present at an out-of-hospital cardiac arrest. METHODS AND RESULTS: One-hundred and twenty-eight semistructured qualitative interviews with CPR-trained lay bystanders...... obligation to act. CONCLUSIONS: Several factors other than previous hands-on CPR training facilitate lay bystander instigation of CPR and AED use. The recognition and modification of these factors may increase lay bystander CPR rates and patient survival following an out-of-hospital cardiac arrest....

  2. Mechanism of protection of bystander cells by exogenous carbon monoxide: Impaired response to damage signal of radiation-induced bystander effect

    International Nuclear Information System (INIS)

    Han, W.; Yu, K.N.; Wu, L.J.; Wu, Y.C.; Wang, H.Z.

    2011-01-01

    A protective effect of exogenous carbon monoxide (CO), generated by CO releasing molecule ticarbonyldichlororuthenium (II) dimer (CORM-2), on the bystander cells from the toxicity of radiation-induced bystander effect (RIBE) was revealed in our previous study. In the present work, a possible mechanism of this CO effect was investigated. The results from medium transfer experiments showed that α-particle irradiated Chinese hamster ovary (CHO) cells would release nitric oxide (NO), which was detected with specific NO fluorescence probe, to induce p53 binding protein 1 (BP1) formation in the cell population receiving the medium, and the release peak was found to be at 1 h post irradiation. Treating the irradiated or bystander cells separately with CO (CORM-2) demonstrated that CO was effective in the bystander cells but not the irradiated cells. Measurements of NO production and release with a specific NO fluorescence probe also showed that CO treatment did not affect the production and release of NO by irradiated cells. Protection of CO on cells to peroxynitrite, an oxidizing free radical from NO, suggested that CO might protect bystander cells via impaired response of bystander cells to NO, a RIBE signal in our research system.

  3. Mechanism of protection of bystander cells by exogenous carbon monoxide: Impaired response to damage signal of radiation-induced bystander effect

    Energy Technology Data Exchange (ETDEWEB)

    Han, W. [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Kowloon (Hong Kong); Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Yu, K.N., E-mail: peter.yu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Kowloon (Hong Kong); Wu, L.J. [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Wu, Y.C. [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230029 (China); Wang, H.Z. [Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2011-05-10

    A protective effect of exogenous carbon monoxide (CO), generated by CO releasing molecule ticarbonyldichlororuthenium (II) dimer (CORM-2), on the bystander cells from the toxicity of radiation-induced bystander effect (RIBE) was revealed in our previous study. In the present work, a possible mechanism of this CO effect was investigated. The results from medium transfer experiments showed that {alpha}-particle irradiated Chinese hamster ovary (CHO) cells would release nitric oxide (NO), which was detected with specific NO fluorescence probe, to induce p53 binding protein 1 (BP1) formation in the cell population receiving the medium, and the release peak was found to be at 1 h post irradiation. Treating the irradiated or bystander cells separately with CO (CORM-2) demonstrated that CO was effective in the bystander cells but not the irradiated cells. Measurements of NO production and release with a specific NO fluorescence probe also showed that CO treatment did not affect the production and release of NO by irradiated cells. Protection of CO on cells to peroxynitrite, an oxidizing free radical from NO, suggested that CO might protect bystander cells via impaired response of bystander cells to NO, a RIBE signal in our research system.

  4. Anisotropic gravitational instability

    International Nuclear Information System (INIS)

    Polyachenko, V.L.; Fridman, A.M.

    1988-01-01

    Exact solutions of stability problems are obtained for two anisotropic gravitational systems of different geometries - a layer of finite thickness at rest and a rotating cylinder of finite radius. It is shown that the anisotropic gravitational instability which develops in both cases is of Jeans type. However, in contrast to the classical aperiodic Jeans instability, this instability is oscillatory. The physics of the anisotropic gravitational instability is investigated. It is shown that in a gravitating layer this instability is due, in particular, to excitation of previously unknown interchange-Jeans modes. In the cylinder, the oscillatory Jeans instability is associated with excitation of a rotational branch, this also being responsible for the beam gravitational instability. This is the reason why this instability and the anisotropic gravitational instability have so much in common

  5. Response to Commentaries on Bystander Training as Leadership Training.

    Science.gov (United States)

    Katz, Jackson

    2018-03-01

    In this article, the author responds to three commentaries about his article "Bystander Training as Leadership Training: Notes on the Origins, Philosophy, and Pedagogy of the Mentors in Violence Prevention Model," published in this volume. Topics covered in the commentaries and response include questions about evaluation and evidence for program effectiveness; the necessity for gender violence prevention education to be gender transformative and part of a comprehensive, multilevel prevention approach, especially for adolescents; and the degree to which Mentors in Violence Prevention (MVP), as a "social justice"-oriented program, incorporates intersectional and anti-oppression frameworks and perspectives.

  6. Helminthiasis, bystander diseases and vaccines: analysis of interaction.

    Science.gov (United States)

    Markus, Miles B; Fincham, John E

    2007-11-01

    Helminthiasis has assumed a new medical and veterinary significance following the recognition of its immunomodulatory consequences for the severity of bystander conditions and the efficacy of immunization against non-helminthic diseases of humans and livestock. Recent papers by Jackson et al. and Turner et al. have an important bearing on research in these areas. One of the implications of their work is that the parasitological criterion of egg-positivity versus egg-negativity is too simplistic to use in co-infection and related studies unless accompanied by immunological analysis.

  7. What role for DNA damage and repair in the bystander response?

    International Nuclear Information System (INIS)

    Prise, Kevin M.; Folkard, Melvyn; Kuosaite, Virginija; Tartier, Laurence; Zyuzikov, Nikolai; Shao, Chunlin

    2006-01-01

    The radiation-induced bystander effect challenges the accepted paradigm of direct DNA damage in response to energy deposition driving the biological consequences of radiation exposure. With the bystander response, cells which have not been directly exposed to radiation respond to their neighbours being targeted. In our own studies we have used novel targeted microbeam approaches to specifically irradiate parts of individual cells within a population to quantify the bystander response and obtain mechanistic information. Using this approach it has become clear that energy deposited by radiation in nuclear DNA is not required to trigger the effect, with cytoplasmic irradiation required. Irradiated cells also trigger a bystander response regardless of whether they themselves live or die, suggesting that the phenotype of the targeted cell is not a determining factor. Despite this however, a range of evidence has shown that repair status is important for dealing with the consequences of a bystander signal. Importantly, repair processes involved in the processing of dsb appear to be involved suggesting that the bystander response involves the delayed or indirect production of dsb-type lesions in bystander cells. Whether these are infact true dsb or complexes of oxidised bases in combination with strand breaks and the mechanisms for their formation, remains to be elucidated

  8. The development of bystander intentions and social-moral reasoning about intergroup verbal aggression.

    Science.gov (United States)

    Palmer, Sally B; Rutland, Adam; Cameron, Lindsey

    2015-11-01

    A developmental intergroup approach was taken to examine the development of prosocial bystander intentions among children and adolescents. Participants as bystanders (N = 260) aged 8-10 and 13-15 years were presented with scenarios of direct aggression between individuals from different social groups (i.e., intergroup verbal aggression). These situations involved either an ingroup aggressor and an outgroup victim or an outgroup aggressor and an ingroup victim. This study focussed on the role of intergroup factors (group membership, ingroup identification, group norms, and social-moral reasoning) in the development of prosocial bystander intentions. Findings showed that prosocial bystander intentions declined with age. This effect was partially mediated by the ingroup norm to intervene and perceived severity of the verbal aggression. However, a moderated mediation analysis showed that only when the victim was an ingroup member and the aggressor an outgroup member did participants become more likely with age to report prosocial bystander intentions due to increased ingroup identification. Results also showed that younger children focussed on moral concerns and adolescents focussed more on psychological concerns when reasoning about their bystander intention. These novel findings help explain the developmental decline in prosocial bystander intentions from middle childhood into early adolescence when observing direct intergroup aggression. © 2015 The British Psychological Society.

  9. Exosome-mediated microRNA transfer plays a role in radiation-induced bystander effect.

    Science.gov (United States)

    Xu, Shuai; Wang, Jufang; Ding, Nan; Hu, Wentao; Zhang, Xurui; Wang, Bing; Hua, Junrui; Wei, Wenjun; Zhu, Qiyun

    2015-01-01

    Bystander effects can be induced through cellular communication between irradiated cells and non-irradiated cells. The signals that mediate this cellular communication, such as cytokines, reactive oxygen species, nitric oxide and even microRNAs, can be transferred between cells via gap junctions or extracellular medium. We have previously reported that miR-21, a well described DDR (DNA damage response) microRNA, is involved in radiation-induced bystander effects through a medium-mediated way. However, the mechanisms of the microRNA transfer have not been elucidated in details. In the present study, it was found that exosomes isolated from irradiated conditioned medium could induce bystander effects. Furthermore, we demonstrated plenty of evidences that miR-21, which is up-regulated as a result of mimic transfection or irradiation, can be transferred from donor or irradiated cells into extracellular medium and subsequently get access to the recipient or bystander cells through exosomes to induce bystander effects. Inhibiting the miR-21 expression in advance can offset the bystander effects to some extent. From all of these results, it can be concluded that the exosome-mediated microRNA transfer plays an important role in the radiation-induced bystander effects. These findings provide new insights into the functions of microRNAs and the cellular communication between the directly irradiated cells and the non-irradiated cells.

  10. New aspects of studies on stress response. Radiation-induced bystander effect

    International Nuclear Information System (INIS)

    Matsumoto, Hideki; Hayashi, Sachiko; Jin, Zhao-Hui; Hatashita, Masanori; Kano, Eiichi

    2001-01-01

    This review describes the bystander effect which is the secondary stress response induced by the primary target affected by radiation and other environmental factors. The bystander effect can be exerted from the primary target cells through the gap junction, through interaction between ligands and receptors, through interaction between secreted bystander factors and receptors and through secreted bystander factors. Through the first, the typical one firstly shown in AG1521 cells is that, despite the pass of only 2% of irradiated α-particles through the target cell nucleus, much more cells respond to express p53 and p21/WAF1. Through the second, the Fas/Fas ligand in the target induce apoptosis of the non-target cells. As for the third, participation of cytokines and growth factors is suggested. Many investigations concern the fourth of bystander effects by the bystander factors: e.g., authors have studied the effects of X-ray, carbon beam or hyperthermia on nitric oxide synthase induction in A-172 cells. Studies of bystander effects possibly extend the concept of radiation biology. (K.H.)

  11. TakeCARE, a Video to Promote Bystander Behavior on College Campuses: Replication and Extension.

    Science.gov (United States)

    Jouriles, Ernest N; Sargent, Kelli S; Salis, Katie Lee; Caiozzo, Christina; Rosenfield, David; Cascardi, Michele; Grych, John H; O'Leary, K Daniel; McDonald, Renee

    2017-08-01

    Previous research has demonstrated that college students who view TakeCARE, a video bystander program designed to encourage students to take action to prevent sexual and relationship violence (i.e., bystander behavior), display more bystander behavior relative to students who view a control video. The current study aimed to replicate and extend these findings by testing two different methods of administering TakeCARE and examining moderators of TakeCARE's effects on bystander behavior. Students at four universities ( n = 557) were randomly assigned to one of three conditions: (a) view TakeCARE in a monitored computer lab, (b) view TakeCARE at their own convenience after receiving an email link to the video, or (c) view a video about study skills (control group). Participants completed measures of bystander behavior at baseline and at a 1-month follow-up. Participants in both TakeCARE conditions reported more bystander behavior at follow-up assessments, compared with participants in the control condition. The beneficial effect of TakeCARE did not differ significantly across administration methods. However, the effects of TakeCARE on bystander behavior were moderated by students' perceptions of campus responsiveness to sexual violence, with more potent effects when students perceived their institution as responsive to reports of sexual violence.

  12. The effect of melanin on the bystander effect in human keratinocytes

    Energy Technology Data Exchange (ETDEWEB)

    Mosse, I. [Institute of Genetics and Cytology of the National Academy of Sciences, Academicheskaya Str. 27, Minsk (Belarus)]. E-mail: i.mosse@igc.bas-net.by; Marozik, P. [Institute of Genetics and Cytology of the National Academy of Sciences, Academicheskaya Str. 27, Minsk (Belarus); Radiation and Environmental Science Centre, DIT, Dublin 8 (Ireland); Seymour, C. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ont. (Canada); Mothersill, C. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ont. (Canada)

    2006-05-11

    The influence of melanin on radiation-induced bystander effects has been studied. Melanin is known to be a natural substance with proved radioprotective properties in different organisms and cell lines. It is non-toxic and is effective against acute and chronic irradiation. The lower the radiation dose, the higher the relative impact of melanin protection. In this study influence of melanin on human keratinocytes (HPV-G cells) has been studied using the colony-forming assay. We have shown that bystander donor medium from 0.5 Gy irradiated cells when transferred to unirradiated cells, caused almost the same effect as direct irradiation. Melanin increased the colony-forming ability of bystander recipient cells when it was added into culture medium before irradiation. The effect of melanin added after irradiation was to produce less protection in both the directly irradiated and bystander medium treated groups. The absorption spectrum of the filtered medium is identical to one of the intact culture medium showing that melanin was not present in filtered medium. Thus, it cannot protect recipient cells but reduces the amount of the bystander effect. It is concluded that melanin added before irradiation effectively decreased the radiation dose. The reduction of the impact of the bystander signal on recipient cells when melanin was added to the donor medium after harvest but before filtration, may mean that the bystander signal has a physical component as melanin can absorb all types of physical energy.

  13. Intercellular and intracellular signaling pathways mediating ionizing radiation-induced bystander effects

    International Nuclear Information System (INIS)

    Hamada, Nobuyuki; Hara, Takamitsu; Kobayashi, Yasuhiko; Matsumoto, Hideki

    2007-01-01

    A rapidly growing body of experimental evidence indicates that ionizing radiation induces biological effects in non-irradiated bystander cells that have received signals from adjacent or distant irradiated cells. This phenomenon, which has been termed the ionizing radiation-induced bystander effect, challenges the long-standing paradigm that radiation traversal through the nucleus of a cell is a prerequisite to elicit genetic damage or a biological response. Bystander effects have been observed in a number of experimental systems, and cells whose nucleus or cytoplasm is irradiated exert bystander responses. Bystander cells manifest a multitude of biological consequences, such as genetic and epigenetic changes, alterations in gene expression, activation of signal transduction pathways, and delayed effects in their progeny. Several mediating mechanisms have been proposed. These involve gap junction-mediated intercellular communication, secreted soluble factors, oxidative metabolism, plasma membrane-bound lipid rafts, and calcium fluxes. This paper reviews briefly the current knowledge of the bystander effect with a focus on proposed mechanisms. The potential benefit of bystander effects to cancer radiotherapy will also be discussed. (author)

  14. The effect of melanin on the bystander effect in human keratinocytes

    International Nuclear Information System (INIS)

    Mosse, I.; Marozik, P.; Seymour, C.; Mothersill, C.

    2006-01-01

    The influence of melanin on radiation-induced bystander effects has been studied. Melanin is known to be a natural substance with proved radioprotective properties in different organisms and cell lines. It is non-toxic and is effective against acute and chronic irradiation. The lower the radiation dose, the higher the relative impact of melanin protection. In this study influence of melanin on human keratinocytes (HPV-G cells) has been studied using the colony-forming assay. We have shown that bystander donor medium from 0.5 Gy irradiated cells when transferred to unirradiated cells, caused almost the same effect as direct irradiation. Melanin increased the colony-forming ability of bystander recipient cells when it was added into culture medium before irradiation. The effect of melanin added after irradiation was to produce less protection in both the directly irradiated and bystander medium treated groups. The absorption spectrum of the filtered medium is identical to one of the intact culture medium showing that melanin was not present in filtered medium. Thus, it cannot protect recipient cells but reduces the amount of the bystander effect. It is concluded that melanin added before irradiation effectively decreased the radiation dose. The reduction of the impact of the bystander signal on recipient cells when melanin was added to the donor medium after harvest but before filtration, may mean that the bystander signal has a physical component as melanin can absorb all types of physical energy

  15. Bystanders intervene to impede grooming in Western chimpanzees and sooty mangabeys

    Science.gov (United States)

    Samuni, Liran; Preis, Anna; Wittig, Roman M.

    2017-01-01

    Grooming interactions benefit groomers, but may have negative consequences for bystanders. Grooming limits bystanders' grooming access and ensuing alliances could threaten the bystander's hierarchy rank or their previous investment in the groomers. To gain a competitive advantage, bystanders could intervene into a grooming bout to increase their own grooming access or to prevent the negative impact of others' grooming. We tested the impact of dominance rank and social relationships on grooming intervention likelihood and outcome in two sympatric primate species, Western chimpanzees (Pan troglodytes verus) and sooty mangabeys (Cercocebus atys atys). In both species, rather than increasing their own access to preferred partners, bystanders intervened mainly when an alliance between groomers could have a negative impact on them: when the lower-ranking groomer was close to the bystander in rank, when either groomer was an affiliation partner whose services they could lose, or the groomers were not yet strongly affiliated with each other. Thus, bystanders in both species appear to monitor grooming interactions and intervene based on their own dominance rank and social relationships, as well as triadic awareness of the relationship between groomers. While the motivation to intervene did not differ between species, mangabeys appeared to be more constrained by dominance rank than chimpanzees. PMID:29291114

  16. Association of Bystander Interventions With Neurologically Intact Survival Among Patients With Bystander-Witnessed Out-of-Hospital Cardiac Arrest in Japan.

    Science.gov (United States)

    Nakahara, Shinji; Tomio, Jun; Ichikawa, Masao; Nakamura, Fumiaki; Nishida, Masamichi; Takahashi, Hideto; Morimura, Naoto; Sakamoto, Tetsuya

    2015-07-21

    Neurologically intact survival after out-of-hospital cardiac arrest (OHCA) has been increasing in Japan. However, associations between increased prehospital care, including bystander interventions and increases in survival, have not been well estimated. To estimate the associations between bystander interventions and changes in neurologically intact survival among patients with OHCA in Japan. Retrospective descriptive study using data from Japan's nationwide OHCA registry, which started in January 2005. The registry includes all patients with OHCA transported to the hospital by emergency medical services (EMS) and recorded patients' characteristics, prehospital interventions, and outcomes. Participants were 167,912 patients with bystander-witnessed OHCA of presumed cardiac origin in the registry between January 2005 and December 2012. Prehospital interventions by bystander, including defibrillation using public-access automated external defibrillators and chest compression. Neurologically intact survival was defined as Glasgow-Pittsburgh cerebral performance category score 1 or 2 and overall performance category scores 1 or 2 at 1 month or at discharge. The association between the interventions and neurologically intact survival was evaluated. From 2005 to 2012, the number of bystander-witnessed OHCAs of presumed cardiac origin increased from 17,882 (14.0 per 100,000 persons [95% CI, 13.8-14.2]) to 23,797 (18.7 per 100,000 persons [95% CI, 18.4-18.9]), and neurologically intact survival increased from 587 cases (age-adjusted proportion, 3.3% [95% CI, 3.0%-3.5%]) to 1710 cases (8.2% [95% CI, 7.8%-8.6%]). The rates of bystander chest compression increased from 38.6% to 50.9%, bystander-only defibrillation increased from 0.1% to 2.3%, bystander defibrillation combined with EMS defibrillation increased from 0.1% to 1.4%, and EMS-only defibrillation decreased from 26.6% to 23.5%. Performance of bystander chest compression, compared with no bystander chest compression

  17. Rescue Effects: Irradiated Cells Helped by Unirradiated Bystander Cells

    Science.gov (United States)

    Lam, R. K. K.; Fung, Y. K.; Han, W.; Yu, K. N.

    2015-01-01

    The rescue effect describes the phenomenon where irradiated cells or organisms derive benefits from the feedback signals sent from the bystander unirradiated cells or organisms. An example of the benefit is the mitigation of radiation-induced DNA damages in the irradiated cells. The rescue effect can compromise the efficacy of radioimmunotherapy (RIT) (and actually all radiotherapy). In this paper, the discovery and subsequent confirmation studies on the rescue effect were reviewed. The mechanisms and the chemical messengers responsible for the rescue effect studied to date were summarized. The rescue effect between irradiated and bystander unirradiated zebrafish embryos in vivo sharing the same medium was also described. In the discussion section, the mechanism proposed for the rescue effect involving activation of the nuclear factor κB (NF-κB) pathway was scrutinized. This mechanism could explain the promotion of cellular survival and correct repair of DNA damage, dependence on cyclic adenosine monophosphate (cAMP) and modulation of intracellular reactive oxygen species (ROS) level in irradiated cells. Exploitation of the NF-κB pathway to improve the effectiveness of RIT was proposed. Finally, the possibility of using zebrafish embryos as the model to study the efficacy of RIT in treating solid tumors was also discussed. PMID:25625514

  18. X-ray-induced bystander response reduce spontaneous mutations in V79 cells

    International Nuclear Information System (INIS)

    Maeda, Munetoshi; Kobayashi, Katsumi; Matsumoto, Hideki; Usami, Noriko; Tomiya, Masanori

    2013-01-01

    The potential for carcinogenic risks is increased by radiation-induced bystander responses; these responses are the biological effects in unirradiated cells that receive signals from the neighboring irradiated cells. Bystander responses have attracted attention in modern radiobiology because they are characterized by non-linear responses to low-dose radiation. We used a synchrotron X-ray microbeam irradiation system developed at the Photon Factory, High Energy Accelerator Research Organization, KEK, and showed that nitric oxide (NO)-mediated bystander cell death increased biphasically in a dose-dependent manner. Here, we irradiated five cell nuclei using 10 × 10 µm 2 5.35 keV X-ray beams and then measured the mutation frequency at the hypoxanthine-guanosine phosphoribosyl transferase (HPRT) locus in bystander cells. The mutation frequency with the null radiation dose was 2.6 × 10 -5 (background level), and the frequency decreased to 5.3 × 10 -6 with a dose of approximately 1 Gy (absorbed dose in the nucleus of irradiated cells). At high doses, the mutation frequency returned to the background level. A similar biphasic dose-response effect was observed for bystander cell death. Furthermore, we found that incubation with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), a specific scavenger of NO, suppressed not only the biphasic increase in bystander cell death but also the biphasic reduction in mutation frequency of bystander cells. These results indicate that the increase in bystander cell death involves mechanisms that suppress mutagenesis. This study has thus shown that radiation-induced bystander responses could affect processes that protect the cell against naturally occurring alterations such as mutations. (author)

  19. Dispatcher-assisted bystander cardiopulmonary resuscitation and survival in out-of-hospital cardiac arrest.

    Science.gov (United States)

    Hagihara, Akihito; Onozuka, Daisuke; Shibuta, Hidetoshi; Hasegawa, Manabu; Nagata, Takashi

    2018-04-19

    Bystander cardiopulmonary resuscitation (CPR) is critical to the survival of patients with out-of-hospital cardiac arrest (OHCA). However, it is unknown whether bystander CPR with or without dispatcher assistance is more effective or why. Thus, we evaluated the association between dispatcher-assisted bystander CPR (vs. bystander CPR without dispatcher assistance) and survival of patients with OHCA. This is a retrospective, nonrandomized, observational study using national registry data for all OHCAs. We performed a propensity analysis. Patients with OHCA of cardiac origin were 18-100 years of age and received bystander chest compression in Japan between 2005 and 2014. Outcome measures were bystander rescue breathing, return of spontaneous circulation (ROSC) before hospital arrival, and survival and Cerebral Performance Category (CPC) 1 or 2 at 1 month after the event. During the study period, 1,176,351 OHCAs occurred, and 87,400 cases met the inclusion criteria. Among propensity-matched patients, a negative association was observed between dispatcher-assisted bystander CPR and outcome measures in a fully-adjusted model [odds ratio (OR) (95% CI) for ROSC = 0.87 (0.78-0.97), P < 0.05; OR (95% CI) for 1-month survival = 0.81 (0.65-1.00), P < 0.05; OR (95% CI) for CPC 1 or 2 = 0.64 (0.43-0.93), P < 0.05]. OR of survival for dispatcher-assisted bystander CPR tended to decrease as the emergency medical services response time increased. Survival benefit was less for dispatcher-assisted bystander CPR with dispatcher assistance than without dispatcher assistance. Low quality is hypothesized to be the cause of the reduced benefit. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Radiation induced bystander effects: mechanisms and implication for low dose radiation risk assessment

    International Nuclear Information System (INIS)

    Hei, T.L.; Randers-Pehrson, G.; Zhou, H.

    2003-01-01

    Using a precision microbeam to target an exact fraction of cells in a population and irradiated their nuclei with exactly one alpha particle each, we found that the frequencies of induced mutations and chromosomal changes in populations where some known fractions of nuclei were hit are consistent with non-hit cells contributing significantly to the response. In fact, irradiation of 10% of a mammalian cell population with a single alpha particle per cell results in a mutant yield similar to that observed when all of the cells in the population are irradiated. Although the bystander observations have been well established, the underlying mechanism(s) remain largely unknown. There are indications that multiple pathways are involved in the bystander phenomenon and different cell types respond differently to the bystander signaling. In confluent monolayers, there is evident that gap junctional communication is crucial in mediating the bystander effect whereas reactive oxygen and reactive nitrogen species have been implicated as the mediating molecules in sub-confluent cultures. Although p53 is not necessary for the expression of bystander effect, there is evident that repair deficient cells may express a higher bystander response. Using cDNA microarrays, a number of cellular signaling genes have been shown to be differentially expressed among bystander cells. The functional roles of these genes in the bystander effect will be discussed. The bystander observations imply that the relevant target for various radiobiological endpoints is larger than an individual cell and suggest a need to reconsider the validity of the linear extrapolation in making risk estimate for low dose radiation exposure. (Work supported by NIH grants CA 49062 and CA-RR11623)

  1. Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation

    Science.gov (United States)

    Tomita, Masanori; Matsumoto, Hideki; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke; Maeda, Munetoshi; Kobayashi, Yasuhiko

    2015-07-01

    In general, a radiation-induced bystander response is known to be a cellular response induced in non-irradiated cells after receiving bystander signaling factors released from directly irradiated cells within a cell population. Bystander responses induced by high-linear energy transfer (LET) heavy ions at low fluence are an important health problem for astronauts in space. Bystander responses are mediated via physical cell-cell contact, such as gap-junction intercellular communication (GJIC) and/or diffusive factors released into the medium in cell culture conditions. Nitric oxide (NO) is a well-known major initiator/mediator of intercellular signaling within culture medium during bystander responses. In this study, we investigated the NO-mediated bystander signal transduction induced by high-LET argon (Ar)-ion microbeam irradiation of normal human fibroblasts. Foci formation by DNA double-strand break repair proteins was induced in non-irradiated cells, which were co-cultured with those irradiated by high-LET Ar-ion microbeams in the same culture plate. Foci formation was suppressed significantly by pretreatment with an NO scavenger. Furthermore, NO-mediated reproductive cell death was also induced in bystander cells. Phosphorylation of NF-κB and Akt were induced during NO-mediated bystander signaling in the irradiated and bystander cells. However, the activation of these proteins depended on the incubation time after irradiation. The accumulation of cyclooxygenase-2 (COX-2), a downstream target of NO and NF-κB, was observed in the bystander cells 6 h after irradiation but not in the directly irradiated cells. Our findings suggest that Akt- and NF-κB-dependent signaling pathways involving COX-2 play important roles in NO-mediated high-LET heavy-ion-induced bystander responses. In addition, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells to distinguish them from directly irradiated cells, although this may depend on the time

  2. Does Non-Targeted Community CPR Training Increase Bystander CPR Frequency?

    Science.gov (United States)

    Uber, Amy; Sadler, Richard C; Chassee, Todd; Reynolds, Joshua C

    2018-05-01

    Only 37% of out-of-hospital cardiac arrests (OHCA) receive bystander Cardiopulmonary resuscitation (CPR) in Kent County, MI. In May 2014, prehospital providers offered one-time, point-of-contact compression-only CPR training to 2,253 passersby at 7 public locations in Grand Rapids, Michigan. To assess the impact of this intervention, we compared bystander CPR frequency and clinical outcomes in regions surrounding training sites before and after the intervention, adjusting for prehospital covariates. We aimed to assess the effect of this broad, non-targeted intervention on bystander CPR frequency, type of CPR utilized, and clinical outcomes. We also tested for differences in geospatial variation of bystander CPR and clinical outcomes clustered around training sites. Retrospective, observational, before-after study of adult, EMS-treated OHCA in Kent County from January 1, 2010 to December 31, 2015. We generated a 5-kilometer radius surrounding each training site to estimate any geospatial influence that training sites might have on bystander CPR frequency in nearby OHCA cases. Chi-squared, Fisher's exact, and t-tests assessed differences in subject features. Difference-in-differences analysis with generalized estimating equation (GEE) modeling assessed bystander CPR frequency, adjusting for training site, covariates (age, sex, witnessed, shockable rhythm, public location), and clustering around training sites. Similar modeling tested for changes in bystander CPR type, return of spontaneous circulation (ROSC), survival to hospital discharge, and cerebral performance category (CPC) of 1-2 at hospital discharge. We included 899 cases before and 587 cases post-intervention. Overall, we observed no increase in the frequency of bystander CPR or favorable clinical outcomes. We did observe an increase in compression-only CPR, but this was paradoxically restricted to OHCA cases falling outside radii around training sites. In adjusted modeling, the bystander CPR training

  3. DMPD: TLR3 in antiviral immunity: key player or bystander? [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16027039 TLR3 in antiviral immunity: key player or bystander? Schroder M, Bowie AG.... Trends Immunol. 2005 Sep;26(9):462-8. (.png) (.svg) (.html) (.csml) Show TLR3 in antiviral immunity: key player... or bystander? PubmedID 16027039 Title TLR3 in antiviral immunity: key player or bystander? Authors Schr... File (.png) SVG File (.svg) HTML File (.html) CSML File (.csml) Open .csml file with CIOPlayer Open .csml file with CIOPlayer... - ※CIO Playerのご利用上の注意 Open .csml file with CIO Open .csml file with CIO - ※CIOのご利用上の注意 ...

  4. Instabilities in inhomogeneous plasma

    International Nuclear Information System (INIS)

    Mikhailovsky, A.B.

    1983-01-01

    The plasma inhomogeneity across the magnetic field causes a wide class of instabilities which are called instabilities of an inhomogeneous plasma or gradient instabilities. The instabilities that can be studied in the approximation of a magnetic field with parallel straight field lines are treated first, followed by a discussion of the influence of shear on these instabilities. The instabilities of a weakly inhomogeneous plasma with the Maxwellian velocity distribution of particles caused by the density and temperature gradients are often called drift instabilities, and the corresponding types of perturbations are the drift waves. An elementary theory of drift instabilities is presented, based on the simplest equations of motion of particles in the field of low-frequency and long-wavelength perturbations. Following that is a more complete theory of inhomogeneous collisionless plasma instabilities which uses the permittivity tensor and, in the case of electrostatic perturbations, the scalar of permittivity. The results are used to study the instabilities of a strongly inhomogeneous plasma. The instabilities of a plasma in crossed fields are discussed and the electromagnetic instabilities of plasma with finite and high pressure are described. (Auth.)

  5. Association of bystander interventions and hospital length of stay and admission to intensive care unit in out-of-hospital cardiac arrest survivors.

    Science.gov (United States)

    Riddersholm, Signe; Kragholm, Kristian; Mortensen, Rikke Nørmark; Pape, Marianne; Hansen, Carolina Malta; Lippert, Freddy K; Torp-Pedersen, Christian; Christiansen, Christian F; Rasmussen, Bodil Steen

    2017-10-01

    The impact of bystander interventions on post-arrest hospital course is sparsely studied. We examined the association between bystander interventions and length of hospital stay and admission to intensive care unit (ICU) in one-day survivors after OHCA. This cohort study linked data of 4641 one-day OHCA survivors from 2001 to 2014 to data on hospital length of stay and ICU admission. We examined associations between bystander efforts and outcomes using regression, adjusted for age, sex, comorbidities, calendar year and witnessed status. We divided bystander efforts into three categories: 1. No bystander interventions; 2.Bystander CPR only; 3. Bystander defibrillation with or without bystander CPR. For patients surviving to hospital discharge, hospital length of stay was 20days for patients without bystander interventions, compared to 16 for bystander CPR, and 13 for bystander defibrillation. 82% of patients without bystander interventions were admitted to ICU compared to 77.2% for bystander CPR, and 61.2% for bystander defibrillation. In-hospital mortality was 60% in the first category compared to 40.5% and 21.7% in the two latter categories. In regression models, bystander CPR and bystander defibrillation were associated with a reduction of length of hospital stay of 21% (Estimate: 0.79 [95% CI: 0.72-0.86]) and 32% (Estimate: 0.68 [95% CI: 0.59-0.78]), respectively. Both bystander CPR (OR: 0.94 [95% CI: 0.91-0.97]) and bystander defibrillation (OR: 0.81 [0.76-0.85]), were associated with lower risk of ICU admission. Bystander interventions were associated with reduced hospital length of stay and ICU admission, suggesting that these efforts improve recovery in OHCA survivors. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Delayed chromosomal instability caused by large deletion

    International Nuclear Information System (INIS)

    Ojima, M.; Suzuki, K.; Kodama, S.; Watanabe, M.

    2003-01-01

    Full text: There is accumulating evidence that genomic instability, manifested by the expression of delayed phenotypes, is induced by X-irradiation but not by ultraviolet (UV) light. It is well known that ionizing radiation, such as X-rays, induces DNA double strand breaks, but UV-light mainly causes base damage like pyrimidine dimers and (6-4) photoproducts. Although the mechanism of radiation-induced genomic instability has not been thoroughly explained, it is suggested that DNA double strand breaks contribute the induction of genomic instability. We examined here whether X-ray induced gene deletion at the hprt locus induces delayed instability in chromosome X. SV40-immortalized normal human fibroblasts, GM638, were irradiated with X-rays (3, 6 Gy), and the hprt mutants were isolated in the presence of 6-thioguanine (6-TG). A 2-fold and a 60-fold increase in mutation frequency were found by 3 Gy and 6 Gy irradiation, respectively. The molecular structure of the hprt mutations was determined by multiplex polymerase chain reaction of nine exons. Approximately 60% of 3 Gy mutants lost a part or the entire hprt gene, and the other mutants showed point mutations like spontaneous mutants. All 6 Gy mutants show total gene deletion. The chromosomes of the hprt mutants were analyzed by Whole Human Chromosome X Paint FISH or Xq telomere FISH. None of the point or partial gene deletion mutants showed aberrations of X-chromosome, however total gene deletion mutants induced translocations and dicentrics involving chromosome X. These results suggest that large deletion caused by DNA double strand breaks destabilizes chromosome structure, which may be involved in an induction of radiation-induced genomic instability

  7. Empowering public service workers to face bystander conflict : Enhancing resources through a training intervention

    NARCIS (Netherlands)

    van Erp, K.J.P.M.; Gevers, J.M.P.; Rispens, S.; Demerouti, E.

    2018-01-01

    Public service employees work in occupations that are accompanied with high psychosocial risks. Police, firefighters, and paramedics are increasingly being confronted with argumentative, conflicting bystanders that frustrate them in executing their task. We developed a resource-enhancement

  8. Bystander chronic infection negatively impacts development of CD8+ T cell memory

    Science.gov (United States)

    Stelekati, Erietta; Shin, Haina; Doering, Travis A.; Dolfi, Douglas V.; Ziegler, Carly G.; Beiting, Daniel P.; Dawson, Lucas; Liboon, Jennifer; Wolski, David; Ali, Mohammed-Alkhatim A.; Katsikis, Peter D.; Shen, Hao; Roos, David S.; Haining, W. Nicholas; Lauer, Georg M.; Wherry, E. John

    2014-01-01

    Summary Epidemiological evidence suggests that chronic infections impair immune responses to unrelated pathogens and vaccines. The underlying mechanisms, however, are unclear and distinguishing effects on priming versus development of immunological memory has been challenging. We investigated whether bystander chronic infections impact differentiation of memory CD8+ T cells, the hallmark of protective immunity against intracellular pathogens. Chronic bystander infections impaired development of memory CD8+ T cells in several mouse models and humans. These effects were independent of initial priming and were associated with chronic inflammatory signatures. Chronic inflammation negatively impacted the number of bystander CD8+ T cells and their memory development. Distinct underlying mechanisms of altered survival and differentiation were revealed with the latter regulated by the transcription factors T-bet and Blimp-1. Thus, exposure to prolonged bystander inflammation impairs the effector to memory transition. These data have relevance for immunity and vaccination during persisting infections and chronic inflammation. PMID:24837104

  9. The application of microbeam in the research on radiation-induced bystander effects

    International Nuclear Information System (INIS)

    Xiong Jie; Han Ling

    2002-01-01

    There has been more and more attention to the phenomenon known as radiation-induced bystander effects, which will have a tremendous effect on the research in low -dose radiation biological effects. However, due to the stochastic nature of energy deposition and the random position of tracts, direct evidence for bystander effects and exact results of single particle interacts with a cell cannot be provided by using conventional broad-field irradiation. The availability of microbeam, especially the single particle microbeam in the world, whereby individual cells or precise location of cells can be irradiated with either a single or an exact number of particles provides a useful tool for the research on radiation-induced bystander effects. The author describes the radiation -induced bystander effect and the application of microbeam in the research on it

  10. Recognising out-of-hospital cardiac arrest during emergency calls increases bystander cardiopulmonary resuscitation and survival

    DEFF Research Database (Denmark)

    Viereck, Søren; Møller, Thea Palsgaard; Ersbøll, Annette Kjær

    2017-01-01

    BACKGROUND: Initiation of early bystander cardiopulmonary resuscitation (CPR) depends on bystanders' or medical dispatchers' recognition of out-of-hospital cardiac arrest (OHCA). The primary aim of our study was to investigate if OHCA recognition during the emergency call was associated...... with bystander CPR, return of spontaneous circulation (ROSC), and 30-day survival. Our secondary aim was to identify patient-, setting-, and dispatcher-related predictors of OHCA recognition. METHODS: We performed an observational study of all OHCA patients' emergency calls in the Capital Region of Denmark from...... the association between OHCA recognition and bystander CPR, ROSC, and 30-day survival. Univariable logistic regression analyses were applied to identify predictors of OHCA recognition. RESULTS: We included 779 emergency calls in the analyses. During the emergency calls, 70.1% (n=534) of OHCAs were recognised...

  11. Social Capital and Bystander Behavior in Bullying: Internalizing Problems as a Barrier to Prosocial Intervention.

    Science.gov (United States)

    Jenkins, Lyndsay N; Fredrick, Stephanie Secord

    2017-04-01

    Theory and research suggests that individuals with greater social capital (i.e., resources and benefits gained from relationships, experiences, and social interactions) may be more likely to be active, prosocial bystanders in bullying situations. Therefore, the goal of the current study was to examine the association of social capital (social support and social skills) with prosocial bystander behavior, and the role of internalizing problems as a potential barrier to this relation among 299 students (45.8% girls, 95% White) in sixth, seventh, and eighth grades. Results indicate a positive relation between social capital and prosocial bystander behavior. In addition, internalizing problems were a significant risk factor that may hinder youth-particularly girls-from engaging in defending behavior. Prosocial bystanders are an essential component to prevent and reduce bullying and further research is needed to better understand how to foster prosocial behavior in bullying situations, perhaps by utilizing social capital, related to school bullying.

  12. Addressing bystander exposure to agricultural pesticides in life cycle impact assessment

    DEFF Research Database (Denmark)

    Ryberg, Morten Walbech; Rosenbaum, Ralph K.; Mosqueron, Luc

    2018-01-01

    Residents living near agricultural fields may be exposed to pesticides drifting from the fields after application to different field crops. To address this currently missing exposure pathway in life cycle assessment (LCA), we developed a modeling framework for quantifying exposure of bystanders...... magnitude of individual bystanders can be substantially larger than the exposure of populations not living in the proximity to agricultural fields. Our framework for assessing bystander exposure to pesticide applications closes a relevant gap in the exposure assessment included in LCA for agricultural...... to pesticide spray drift from agricultural fields. Our framework consists of three parts addressing: (1) loss of pesticides from an agricultural field via spray drift; (2) environmental fate of pesticide in air outside of the treated field; and (3) exposure of bystanders to pesticides via inhalation...

  13. Lack of Bystander Effects From High LET Radiation For Early Cytogenetic Endpoints.

    Energy Technology Data Exchange (ETDEWEB)

    Groesser, Torsten; Cooper, Brian; Rydberg, Bjorn

    2008-05-07

    The aim of this work was to study radiation-induced bystander effects for early cytogenetic end points in various cell lines using the medium transfer technique after exposure to high- and low-LET radiation. Cells were exposed to 20 MeV/ nucleon nitrogen ions, 968 MeV/nucleon iron ions, or 575 MeV/nucleon iron ions followed by transfer of the conditioned medium from the irradiated cells to unirradiated test cells. The effects studied included DNA double-strand break induction, {gamma}-H2AX focus formation, induction of chromatid breaks in prematurely condensed chromosomes, and micronucleus formation using DNA repair-proficient and -deficient hamster and human cell lines (xrs6, V79, SW48, MO59K and MO59J). Cell survival was also measured in SW48 bystander cells using X rays. Although it was occasionally possible to detect an increase in chromatid break levels using nitrogen ions and to see a higher number of {gamma}-H2AX foci using nitrogen and iron ions in xrs6 bystander cells in single experiments, the results were not reproducible. After we pooled all the data, we could not verify a significant bystander effect for any of these end points. Also, we did not detect a significant bystander effect for DSB induction or micronucleus formation in these cell lines or for clonogenic survival in SW48 cells. The data suggest that DNA damage and cytogenetic changes are not induced in bystander cells. In contrast, data in the literature show pronounced bystander effects in a variety of cell lines, including clonogenic survival in SW48 cells and induction of chromatid breaks and micronuclei in hamster cells. To reconcile these conflicting data, it is possible that the epigenetic status of the specific cell line or the precise culture conditions and medium supplements, such as serum, may be critical for inducing bystander effects.

  14. Lack of Bystander Effects From High-LET Radiation For Early Cytogenetic End Points

    International Nuclear Information System (INIS)

    Groesser, Torsten; Cooper, Brian; Rydberg, Bjorn

    2008-01-01

    The aim of this work was to study radiation-induced bystander effects for early cytogenetic end points in various cell lines using the medium transfer technique after exposure to high- and low-LET radiation. Cells were exposed to 20 MeV/ nucleon nitrogen ions, 968 MeV/nucleon iron ions, or 575 MeV/nucleon iron ions followed by transfer of the conditioned medium from the irradiated cells to unirradiated test cells. The effects studied included DNA double-strand break induction, γ-H2AX focus formation, induction of chromatid breaks in prematurely condensed chromosomes, and micronucleus formation using DNA repair-proficient and -deficient hamster and human cell lines (xrs6, V79, SW48, MO59K and MO59J). Cell survival was also measured in SW48 bystander cells using X rays. Although it was occasionally possible to detect an increase in chromatid break levels using nitrogen ions and to see a higher number of γ-H2AX foci using nitrogen and iron ions in xrs6 bystander cells in single experiments, the results were not reproducible. After we pooled all the data, we could not verify a significant bystander effect for any of these end points. Also, we did not detect a significant bystander effect for DSB induction or micronucleus formation in these cell lines or for clonogenic survival in SW48 cells. The data suggest that DNA damage and cytogenetic changes are not induced in bystander cells. In contrast, data in the literature show pronounced bystander effects in a variety of cell lines, including clonogenic survival in SW48 cells and induction of chromatid breaks and micronuclei in hamster cells. To reconcile these conflicting data, it is possible that the epigenetic status of the specific cell line or the precise culture conditions and medium supplements, such as serum, may be critical for inducing bystander effects.

  15. Temporal variations in dispatcher-assisted and bystander-initiated resuscitation efforts.

    Science.gov (United States)

    Yamashita, Akira; Maeda, Tetsuo; Myojo, Yasuhiro; Wato, Yukihiro; Ohta, Keisuke; Inaba, Hideo

    2018-04-03

    To investigate temporal variations in dispatcher-assisted and bystander-initiated resuscitation efforts and their association with survival after bystander-witnessed out-of-hospital cardiac arrests (OHCAs). We retrospectively analyzed the neurologically favorable 1-month survival and the parameters related to dispatcher assisted cardiopulmonary resuscitation (DA-CPR) and bystander CPR (BCPR) for 227,524 OHCA patients between 2007 and 2013 in Japan. DA-CPR sensitivity for OHCAs, bystander's compliance to DA-CPR assessed by the proportion of bystanders who follow DA-CPR, and performance of BCPR measured by the rate of bystander-initiated CPR in patients without DA-CPR were calculated as indices of resuscitation efforts. Performance of BCPR was only similar to temporal variations in the survival (correlation between hourly paired values, R 2 =0.263, P=0.01): a lower survival rate (3.4% vs 4.2%) and performance of BCPR (23.1% vs 30.8%) during night-time (22:00-5:59) than during non-night-time. In subgroup analyses based on interaction tests, all three indices deteriorated during night-time when OHCAs were witnessed by non-family (adjusted odds ratio, 0.73-0.82), particularly in non-elderly patients. The rate of public access defibrillation for these OHCAs markedly decreased during night-time (adjusted odds ratio, 0.49) with delayed emergency calls and BCPR initiation. Multivariable logistic regression analyses revealed that the survival rate of non-family-witnessed OHCAs was 1.83-fold lower during night-time than during non-night-time. Dispatcher-assisted and bystander-initiated resuscitation efforts are low during night-time in OHCAs witnessed by non-family. A divisional alert system to recruit well-trained individuals is needed in order to improve the outcomes of night-time OHCAs witnessed by non-family bystanders. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Molecular pathways in the bystander response of cells exposed to very low fluences of alpha particles

    International Nuclear Information System (INIS)

    Little, J.B.

    2000-01-01

    Full text: We have examined biological effects in cell populations exposed to very low mean doses of alpha radiation by which only a small fraction of the cells are actually traversed by an alpha particle. We showed earlier that an enhanced frequency of sister chromatid exchanges and HPRT mutations occur in the non-irradiated, 'bystander' cells. The frequency of mutations induced by a single alpha particle traversing the nucleus of a cell was increased nearly fivefold at the lowest fluence studied, a result of mutations occurring in bystander cells. This was associated with a similar increase in the induction of micronuclei, indicating the induction of DNA damage in bystander cells. In order to gain information concerning molecular pathways, we studied changes in gene expression in bystander cells in confluent cultures of human diploid fibroblasts or mouse embryo-derived fibroblasts (MEFs) by western analysis and in-situ immunofluorescence. The expression levels of p53, p21 Waf1 and p34 cdc2 were significantly modulated in bystander cells. The upregulation of p53 and p21 Waf1 did not occur in cultures irradiated at low density, and was markedly reduced in the presence of the gap junction inhibitor lindane. The importance of gap-junction mediated intercellular communication was confirmed in connexin-43 knockout MEFs. Western blot analyses and electrophoretic mobility shift assays indicate that the bystander response is suppressed by incubation with superoxide dismutase as well as an inhibitor of NADPH oxidase, and is associated with the induction of NFKB, suggesting the effect is mediated by oxidative stress. The stress-activated protein kinase p38 and its downstream effector ATF2 are also induced in bystander cells independent of oxidative stress. These results will be discussed in terms of whether activation of the p53 damage response pathway is the direct result of signaling from irradiated cells, or rather is a consequence of DNA induced damage in the bystander

  17. Influence of Magnolol on the bystander effect induced by alpha-particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wong, T.P.W.; Law, Y.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Tse, A.K.W.; Fong, W.F. [Research and Development Division, School of Chinese Medicine, Hong Kong Baptist University, Baptist University Road, Kowloon Tong (Hong Kong); Yu, K.N. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)], E-mail: peter.yu@cityu.edu.hk

    2010-04-15

    In this work, the influence of Magnolol on the bystander effect in alpha-particle irradiated Chinese hamster ovary (CHO) cells was examined. The bystander effect was studied through medium transfer experiments. Cytokinesis-block micronucleus (CBMN) assay was performed to quantify the chromosome damage induced by alpha-particle irradiation. Our results showed that the alpha-particle induced micronuclei (MN) frequencies were suppressed with the presence of Magnolol.

  18. Bystander motivation in bullying incidents: to intervene or not to intervene?

    Science.gov (United States)

    Thornberg, Robert; Tenenbaum, Laura; Varjas, Kris; Meyers, Joel; Jungert, Tomas; Vanegas, Gina

    2012-08-01

    This research sought to extend knowledge about bystanders in bullying situations with a focus on the motivations that lead them to different responses. The 2 primary goals of this study were to investigate the reasons for children's decisions to help or not to help a victim when witnessing bullying, and to generate a grounded theory (or conceptual framework) of bystander motivation in bullying situations. Thirty students ranging in age from 9 to 15 years (M = 11.9; SD = 1.7) from an elementary and middle school in the southeastern United States participated in this study. Open- ended, semi-structured interviews were used, and sessions ranged from 30 to 45 minutes. We conducted qualitative methodology and analyses to gain an in-depth understanding of children's perspectives and concerns when witnessing bullying. A key finding was a conceptual framework of bystander motivation to intervene in bullying situations suggesting that deciding whether to help or not help the victim in a bullying situation depends on how bystanders define and evaluate the situation, the social context, and their own agency. Qualitative analysis revealed 5 themes related to bystander motives and included: interpretation of harm in the bullying situation, emotional reactions, social evaluating, moral evaluating, and intervention self-efficacy. Given the themes that emerged surrounding bystanders' motives to intervene or abstain from intervening, respondents reported 3 key elements that need to be confirmed in future research and that may have implications for future work on bullying prevention. These included: first, the potential importance of clear communication to children that adults expect bystanders to intervene when witnessing bullying; second, the potential of direct education about how bystanders can intervene to increase children's self-efficacy as defenders of those who are victims of bullying; and third, the assumption that it may be effective to encourage children's belief that

  19. Bystander apoptosis in human cells mediated by irradiated blood plasma

    Energy Technology Data Exchange (ETDEWEB)

    Vinnikov, Volodymyr, E-mail: vlad.vinnikov@mail.ru [Grigoriev Institute for Medical Radiology of the National Academy of Medical Science of Ukraine (Ukraine); Lloyd, David; Finnon, Paul [Centre for Radiation, Chemical and Environmental Hazards of the Health Protection Agency of the United Kingdom (United Kingdom)

    2012-03-01

    Following exposure to high doses of ionizing radiation, due to an accident or during radiotherapy, bystander signalling poses a potential hazard to unirradiated cells and tissues. This process can be mediated by factors circulating in blood plasma. Thus, we assessed the ability of plasma taken from in vitro irradiated human blood to produce a direct cytotoxic effect, by inducing apoptosis in primary human peripheral blood mononuclear cells (PBM), which mainly comprised G{sub 0}-stage lymphocytes. Plasma was collected from healthy donors' blood irradiated in vitro to 0-40 Gy acute {gamma}-rays. Reporter PBM were separated from unirradiated blood with Histopaque and held in medium with the test plasma for 24 h at 37 Degree-Sign C. Additionally, plasma from in vitro irradiated and unirradiated blood was tested against PBM collected from blood given 4 Gy. Apoptosis in reporter PBM was measured by the Annexin V test using flow cytometry. Plasma collected from unirradiated and irradiated blood did not produce any apoptotic response above the control level in unirradiated reporter PBM. Surprisingly, plasma from irradiated blood caused a dose-dependent reduction of apoptosis in irradiated reporter PBM. The yields of radiation-induced cell death in irradiated reporter PBM (after subtracting the respective values in unirradiated reporter PBM) were 22.2 {+-} 1.8% in plasma-free cultures, 21.6 {+-} 1.1% in cultures treated with plasma from unirradiated blood, 20.2 {+-} 1.4% in cultures with plasma from blood given 2-4 Gy and 16.7 {+-} 3.2% in cultures with plasma from blood given 6-10 Gy. These results suggested that irradiated blood plasma did not cause a radiation-induced bystander cell-killing effect. Instead, a reduction of apoptosis in irradiated reporter cells cultured with irradiated blood plasma has implications concerning oncogenic risk from mutated cells surviving after high dose in vivo irradiation (e.g. radiotherapy) and requires further study.

  20. Ion beam induced luminescence: Relevance to radiation induced bystander effects

    Science.gov (United States)

    Ahmad, S. B.; McNeill, F. E.; Byun, S. H.; Prestwich, W. V.; Seymour, C.; Mothersill, C. E.

    2012-10-01

    The aim of this work is quantify the light emitted as a result of charged particle interaction in materials which may be of relevance to radiation induced "bystander effects" studies. We have developed a system which employs single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. The system uses a fast photomultiplier tube with a peak cathode response at 420 nm. It has been tested in a proof-of-principle experiment using polystyrene targets. Light output, as a result of irradiation, was measured. The luminescence yield appears to have a non-linear behavior with the incident ion fluence: it rises exponentially to an asymptotic value. The target was irradiated with beam energies varying from 1 to 2 MeV and showed saturation at or before an incident fluence rate of 3 × 1013 H+/cm2 s. The average saturation value for the photon output was found to be 40 × 106 cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28 × 103, 10 × 106, and 35 × 106 cps for wavelengths of 280 ± 5 nm, 320 ± 5 nm and 340 ± 5 nm respectively. The light output reaches a maximum value because of damage induced in the polymer. Our measurements indicate a "damage cross section" of the order of 10-14 cm2. The average radiant intensity was found to increase at wavelengths of 280 and 320 nm when the proton energy was increased. This was not found to occur at 340 nm. In conclusion, the light emission at specific wavelengths was found to depend upon the incident proton fluence and the proton energy. The wavelengths of the emitted light measured in this study have significance for the understanding of radiation induced bystander effects.

  1. Bystander apoptosis in human cells mediated by irradiated blood plasma

    International Nuclear Information System (INIS)

    Vinnikov, Volodymyr; Lloyd, David; Finnon, Paul

    2012-01-01

    Following exposure to high doses of ionizing radiation, due to an accident or during radiotherapy, bystander signalling poses a potential hazard to unirradiated cells and tissues. This process can be mediated by factors circulating in blood plasma. Thus, we assessed the ability of plasma taken from in vitro irradiated human blood to produce a direct cytotoxic effect, by inducing apoptosis in primary human peripheral blood mononuclear cells (PBM), which mainly comprised G 0 -stage lymphocytes. Plasma was collected from healthy donors’ blood irradiated in vitro to 0–40 Gy acute γ-rays. Reporter PBM were separated from unirradiated blood with Histopaque and held in medium with the test plasma for 24 h at 37 °C. Additionally, plasma from in vitro irradiated and unirradiated blood was tested against PBM collected from blood given 4 Gy. Apoptosis in reporter PBM was measured by the Annexin V test using flow cytometry. Plasma collected from unirradiated and irradiated blood did not produce any apoptotic response above the control level in unirradiated reporter PBM. Surprisingly, plasma from irradiated blood caused a dose-dependent reduction of apoptosis in irradiated reporter PBM. The yields of radiation-induced cell death in irradiated reporter PBM (after subtracting the respective values in unirradiated reporter PBM) were 22.2 ± 1.8% in plasma-free cultures, 21.6 ± 1.1% in cultures treated with plasma from unirradiated blood, 20.2 ± 1.4% in cultures with plasma from blood given 2–4 Gy and 16.7 ± 3.2% in cultures with plasma from blood given 6–10 Gy. These results suggested that irradiated blood plasma did not cause a radiation-induced bystander cell-killing effect. Instead, a reduction of apoptosis in irradiated reporter cells cultured with irradiated blood plasma has implications concerning oncogenic risk from mutated cells surviving after high dose in vivo irradiation (e.g. radiotherapy) and requires further study.

  2. Bystander's willingness to report theft, physical assault, and sexual assault: the impact of gender, anonymity, and relationship with the offender.

    Science.gov (United States)

    Nicksa, Sarah C

    2014-01-01

    This research examines bystander willingness to report three different crimes to the police or campus authorities among a college student sample (n = 295). Twelve original vignettes varied anonymity when reporting, bystander's relationship with the offender (friend or stranger), and crime type. A factorial analysis of variance showed that main effects were found for crime type, bystander's gender, and bystander's relationship with the offender; anonymity was not significant. The physical assault was the most likely to be reported (4.47), followed by theft (3.26), and sexual assault (2.36). Women were more likely than men to report each crime type, and bystanders who were good friends of the offender were less likely to report than strangers. No two- or three-way interactions were significant, but a significant four-way interaction indicated that anonymity, relationship with the offender, and bystander's gender predicted willingness to report for the sexual assault scenario.

  3. Critical role of gap junction communication, calcium and nitric oxide signaling in bystander responses to focal photodynamic injury.

    Science.gov (United States)

    Calì, Bianca; Ceolin, Stefano; Ceriani, Federico; Bortolozzi, Mario; Agnellini, Andrielly H R; Zorzi, Veronica; Predonzani, Andrea; Bronte, Vincenzo; Molon, Barbara; Mammano, Fabio

    2015-04-30

    Ionizing and nonionizing radiation affect not only directly targeted cells but also surrounding "bystander" cells. The underlying mechanisms and therapeutic role of bystander responses remain incompletely defined. Here we show that photosentizer activation in a single cell triggers apoptosis in bystander cancer cells, which are electrically coupled by gap junction channels and support the propagation of a Ca2+ wave initiated in the irradiated cell. The latter also acts as source of nitric oxide (NO) that diffuses to bystander cells, in which NO levels are further increased by a mechanism compatible with Ca(2+)-dependent enzymatic production. We detected similar signals in tumors grown in dorsal skinfold chambers applied to live mice. Pharmacological blockade of connexin channels significantly reduced the extent of apoptosis in bystander cells, consistent with a critical role played by intercellular communication, Ca2+ and NO in the bystander effects triggered by photodynamic therapy.

  4. Bystanders' responses to offline bullying and cyberbullying: The role of empathy and normative beliefs about aggression.

    Science.gov (United States)

    Machackova, Hana; Pfetsch, Jan

    2016-04-01

    Cyberbullying often takes place with the virtual presence or knowledge of bystanders. While we have some evidence about the determinants of bystanders' responses to offline bullying, we lack empirical studies concerning the variables that influence bystanders' responses to cyberbullying. The current study examines bystanders' responses to offline bullying and cyberbullying incidents. Two types of responses were captured: support toward the victims and the reinforcement of bullies' actions. Using data from 321 German adolescents (ages 12-18; M = 14.99; 44% girls), the association between bystanders' responses and normative beliefs about verbal aggression and cyberaggression, and affective and cognitive empathy, were tested in a path model. Both types of normative beliefs positively predicted the reinforcement of bullies, and normative belief about verbal aggression also predicted support for the victims of offline bullying. Both types of empathy predicted support in offline bullying, but only affective empathy predicted support in cyberbullying. There was no link between affective or cognitive empathy to the reinforcement of bullies. Moreover, bystanders' tendencies to respond supportively to the victim or to reinforce the bully were rather consistent in both cyber- and offline bullying, but there was no link between support and reinforcement. The findings are discussed with regard to implications for prevention and intervention efforts. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  5. An Online Bystander Intervention Program for the Prevention of Sexual Violence.

    Science.gov (United States)

    Kleinsasser, Anne; Jouriles, Ernest N; McDonald, Renee; Rosenfield, David

    2015-07-01

    Because of its high prevalence and serious consequences for victims, sexual violence is a significant problem on college campuses. Sexual assault prevention programs based on the bystander intervention model have been shown to be effective; however, current programs are limited in terms of ease of distribution. To address this issue, we developed and evaluated "Take Care," an online bystander intervention program. To our knowledge, this is the first empirical evaluation of an online bystander intervention program designed to prevent sexual violence. Ninety-three participants (80.6% female, 19.4% male) recruited from social psychology classes at a mid-size university were randomly assigned to view one of two online programs: Take Care or a control program on study skills. Before viewing the programs, participants completed measures of bystander behaviors and feelings of efficacy for performing such behaviors. Measures were administered again post-intervention and at a two-month follow-up assessment. Participants who viewed Take Care reported greater efficacy for engaging in bystander behaviors at post-treatment and two months following treatment, compared to those who viewed the control program. In addition, participants who viewed Take Care reported performing relatively more bystander behaviors for friends at the two-month follow-up assessment, compared to participants who viewed the control program. These results suggest that sexual violence prevention programs may be effectively adapted to an online format.

  6. Relationship between P53 and bystander effect induced by radiated hepatoma cells

    International Nuclear Information System (INIS)

    Zhao Meijia; Shen Bo; Yuan Dexiao; Cheng Honghong; Shao Chunlin

    2009-01-01

    The role of p53 in bystander responses on normal liver cells were investigated by co-culturing irradiated hepatoma cells with non-irradiated bystander Chang liver cells. It was found that radiosensitivity of the hepatoma cells was relative to p53. HepG2 cells with wtp53 had the highest radiosensitivity followed by PLC/PRF/5 cells with mtp53 and Hep3B cells with null-p53. The induction of bystander micronucleus(MN) was observed only in the Chang liver cells that had been co-cultured with HepG2 cells but not co-cultured with PLC/PRF/5 or Hep3B. Also, this bystander MN was relative to the irradiation dose and the cell co-culture rime. When the hepatoma cells were treated with pifithrin-α, a p53 inhibitor, their radiosensitivities were reduced, and the bystander effect was diminished. The results indicate that p53 could regulate not only the radiosensitivity but also the bystander response. (authors)

  7. Dispatcher instruction of chest compression-only CPR increases actual provision of bystander CPR.

    Science.gov (United States)

    Shimamoto, Tomonari; Iwami, Taku; Kitamura, Tetsuhisa; Nishiyama, Chika; Sakai, Tomohiko; Nishiuchi, Tatsuya; Hayashi, Yasuyuki; Kawamura, Takashi

    2015-11-01

    A preceding randomized controlled trial demonstrated that chest compression-only cardiopulmonary resuscitation (CPR) instruction by dispatcher was more effective to increase bystander CPR than conventional CPR instruction. However, the actual condition of implementation of each type of dispatcher instruction (chest compression-only CPR [CCCPR] or conventional CPR with rescue breathing) and provision of bystander CPR in real prehospital settings has not been sufficiently investigated. This registry prospectively enrolled patients aged =>18 years suffering an out-of-hospital cardiac arrest (OHCA) of non-traumatic causes before emergency-medical-service (EMS) arrival, who were considered as target subjects of dispatcher instruction, resuscitated by EMS personnel, and transported to medical institutions in Osaka, Japan from January 2005 through December 2012. The primary outcome measure was provision of CPR by a bystander. Multiple logistic regression analysis was used to assess factors that were potentially associated with provision of bystander CPR. Among 37,283 target subjects of dispatcher instruction, 5743 received CCCPR instruction and 13,926 received conventional CPR instruction. The proportion of CCCPR instruction increased from 5.7% in 2005 to 25.6% in 2012 (p for trend bystander CPR more frequently than conventional CPR instruction group (70.0% versus 62.1%, pbystander CPR compared with conventional CPR instruction (adjusted odds ratio 1.44, 95% CI 1.34-1.55). CCCPR dispatcher instruction among adult OHCA patients significantly increased the actual provision of bystander CPR. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Radiation-induced bystander effects. Mechanisms, biological implications, and current investigations at the Leipzig LIPSION facility

    International Nuclear Information System (INIS)

    Oesterreicher, J.; Prise, K.M.; Michael, B.D.; Vogt, J.; Butz, T.; Tanner, J.M.

    2003-01-01

    Background: The bystander effect is a relatively new area of radiobiological research, which is aimed at studying post-radiation changes in neighboring non-hit cells or tissues. The bystander effect of ionizing irradiation is important after low-dose irradiation in the range of up to 0.2 Gy, where a higher incidence of stochastic damage was observed than was expected from a linear-quadratic model. It is also important when the irradiation of a cell population is highly non-uniform. Objective: This review summarizes most of the important results and proposed bystander effect mechanisms as well as their impact on theory and clinical practice. The literature, in parts contradictory, is collected, the main topics are outlined, and some basic papers are described in more detail. In order to illustrate the microbeam technique, which is considered relevant for the bystander effect research, the state of the Leipzig LIPSION nanoprobe facility is described. Results: The existence of a radiation-induced bystander effect is now generally accepted. The current state of knowledge on it is summarized here. Several groups worldwide are working on understanding its different aspects and its impact on radiobiology and radiation protection. Conclusion: The observation of a bystander effect has posed many questions, and answering them is a challenging topic for radiobiology in the future. (orig.)

  9. Radiation-induced bystander effects. Mechanisms, biological implications, and current investigations at the Leipzig LIPSION facility

    Energy Technology Data Exchange (ETDEWEB)

    Oesterreicher, J. [Dept. of Nuclear Solid State Physics, Univ. of Leipzig (Germany); Dept. of Radiobiology and Immunology, Purkyne Military Medical Academy, Hradec Kralove (Czech Republic); Prise, K.M.; Michael, B.D. [Gray Cancer Inst., Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Vogt, J.; Butz, T. [Dept. of Nuclear Solid State Physics, Univ. of Leipzig (Germany); Tanner, J.M. [Clinic and Polyclinic of Radiation Oncology, Martin Luther Univ. Halle-Wittenberg (Germany)

    2003-02-01

    Background: The bystander effect is a relatively new area of radiobiological research, which is aimed at studying post-radiation changes in neighboring non-hit cells or tissues. The bystander effect of ionizing irradiation is important after low-dose irradiation in the range of up to 0.2 Gy, where a higher incidence of stochastic damage was observed than was expected from a linear-quadratic model. It is also important when the irradiation of a cell population is highly non-uniform. Objective: This review summarizes most of the important results and proposed bystander effect mechanisms as well as their impact on theory and clinical practice. The literature, in parts contradictory, is collected, the main topics are outlined, and some basic papers are described in more detail. In order to illustrate the microbeam technique, which is considered relevant for the bystander effect research, the state of the Leipzig LIPSION nanoprobe facility is described. Results: The existence of a radiation-induced bystander effect is now generally accepted. The current state of knowledge on it is summarized here. Several groups worldwide are working on understanding its different aspects and its impact on radiobiology and radiation protection. Conclusion: The observation of a bystander effect has posed many questions, and answering them is a challenging topic for radiobiology in the future. (orig.)

  10. Radiation induced bystander effect on hepatoma HepG2 cells under hypoxia condition

    International Nuclear Information System (INIS)

    Zhang Jianghong; Jin Yizun; Shao Chunlin; Prise KM

    2009-01-01

    Objective: To investigate radiation induced bystander effect and its mechanism on hepatoma HepG2 cells under hypoxia condition. Methods: Non-irradiated bystander hepatoma cells were co-cultured with irradiated cells or treated with the conditioned medium (CM) from irradiated cells, then micronuclei (MN) were measured for both irradiated cells and bystander cells. Results: The MN yield of irradiated HepG2 cells under hypoxic condition was significantly lower than that under normoxia, the oxygen enhancement ratio of HepG2 cells of MN was 1.6. For both hypoxic and normoxic condition, the MN yield of bystander cells were obviously enhanced to a similar high level after co-culturing with irradiated cells or with CM treatment, and it also correlated with the irradiation dose. When the hypoxic HepG2 cells were treated with either DMSO, a scavenger of reactive oxygen species (ROS), or aminoguanidine, an iNOS inhibitor, the yield of bystander MN was partly diminished, and the reducing rate of DMSO was 42.2%-46.7%, the reducing rate of aminoguanidine was 42% . Conclusion: ROS, NO and their downstream signal factors are involved in the radiation induced bystander effect of hypoxic HepG2 cells. (authors)

  11. Potential association of bystander-patient relationship with bystander response and patient survival in daytime out-of-hospital cardiac arrest.

    Science.gov (United States)

    Tanaka, Yoshio; Maeda, Tetsuo; Kamikura, Takahisa; Nishi, Taiki; Omi, Wataru; Hashimoto, Masaaki; Sakagami, Satoru; Inaba, Hideo

    2015-01-01

    To investigate whether the bystander-patient relationship affects bystander response to out-of-hospital cardiac arrest (OHCA) and patient outcomes depending on the time of day. This population-based observational study in Japan involving 139,265 bystander-witnessed OHCAs (90,426 family members, 10,479 friends/colleagues, and 38,360 others) without prehospital physician involvement was conducted from 2005 to 2009. Factors associated with better bystander response [early emergency call and bystander cardiopulmonary resuscitation (BCPR)] and 1-month neurologically favourable survival were assessed. The rates of dispatcher-assisted CPR during daytime (7:00-18:59) and nighttime (19:00-6:59) were highest in family members (45.6% and 46.1%, respectively, for family members; 28.7% and 29.2%, respectively, for friends/colleagues; and 28.1% and 25.3%, respectively, for others). However, the BCPR rates were lowest in family members (35.5% and 37.8%, respectively, for family members; 43.7% and 37.8%, respectively, for friends/colleagues; and 59.3% and 50.0%, respectively, for others). Large delays (≥ 5 min) in placing emergency calls and initiating BCPR were most frequent in family members. The overall survival rate was lowest (2.7%) for family members and highest (9.1%) for friends/colleagues during daytime. Logistic regression analysis revealed that the effect of bystander relationship on survival was significant only during daytime [adjusted odds ratios (95% CI) for survival from daytime OHCAs with family as reference were 1.51 (1.36-1.68) for friends/colleagues and 1.23 (1.13-1.34) for others]. Family members are least likely to perform BCPR and OHCAs witnessed by family members are least likely to survive during daytime. Different strategies are required for family-witnessed OHCAs. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  12. Association of initial rhythm with neurologically favorable survival in non-shockable out-of-hospital cardiac arrest without a bystander witness or bystander cardiopulmonary resuscitation.

    Science.gov (United States)

    Fukuda, Tatsuma; Ohashi-Fukuda, Naoko; Matsubara, Takehiro; Doi, Kent; Kitsuta, Yoichi; Nakajima, Susumu; Yahagi, Naoki

    2016-05-01

    Out-of-hospital cardiac arrest (OHCA) has a predominantly non-shockable rhythm. Non-shockable rhythm, and the absence of a bystander witness or bystander cardiopulmonary resuscitation (CPR) are associated with poor outcomes. However, the association between the type of non-shockable rhythm and outcomes is not well known. To examine the association between the initial rhythm and neurologically favorable outcomes after non-shockable OHCA without a bystander witness or bystander CPR. In a nationwide, population-based, cohort study, we analyzed 213,984 adult OHCA patients with a non-shockable rhythm who had neither a bystander witness nor bystander CPR. They were identified through the Japanese national OHCA registry data from January 1, 2005 to December 31, 2010. The primary outcome was neurologically favorable survival. Among 213,984 patients, the initial rhythm was Pulseless Electrical Activity (PEA) in 31,179 patients (14.6%) and Asystole in 182,805 patients (85.4%). The neurological outcome was more favorable in PEA than in Asystole (1.4% vs. 0.2%, padvanced airway management, time from call to contact with patient, and calendar year, PEA was associated with an increased neurologically favorable survival rate (odds ratio 7.86; 95% confidence interval 6.81-9.07). In subgroup analysis stratified by age group (18-64, 65-84, or ≥85years), the neurologically favorable survival rate was ≥1% in PEA, even for patients aged ≥85years, but <1% in Asystole among all age groups. PEA and Asystole should not be considered to be identical to non-shockable rhythm, but rather should be clearly distinguished from each other from the perspective of quantitative medical futility. Copyright © 2016 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  13. Regions With Low Rates of Bystander Cardiopulmonary Resuscitation (CPR) Have Lower Rates of CPR Training in Victoria, Australia.

    Science.gov (United States)

    Bray, Janet E; Straney, Lahn; Smith, Karen; Cartledge, Susie; Case, Rosalind; Bernard, Stephen; Finn, Judith

    2017-06-05

    Bystander cardiopulmonary resuscitation (CPR) more than doubles the chance of surviving an out-of-hospital cardiac arrest. Recent data have shown considerable regional variation in bystander CPR rates across the Australian state of Victoria. This study aims to determine whether there is associated regional variation in rates of CPR training and willingness to perform CPR in these communities. We categorized each Victorian postcode as either a low or high bystander CPR region using data on adult, bystander-witnessed, out-of-hospital cardiac arrests of presumed cardiac etiology (n=7175) from the Victorian Ambulance Cardiac Arrest Registry. We then surveyed adult Victorians (n=404) and compared CPR training data of the respondents from low and high bystander CPR regions. Of the 404 adults surveyed, 223 (55%) resided in regions with low bystander CPR. Compared with respondents from high bystander CPR regions, respondents residing in regions with low bystander CPR had lower rates of CPR training (62% versus 75%, P =0.009) and lower self-ratings for their overall knowledge of CPR (76% versus 84%, P =0.04). There were no differences between the regions in their reasons for not having undergone CPR training or in their willingness to perform CPR. Rates of survival for bystander-witnessed, out-of-hospital cardiac arrests were significantly lower in low bystander CPR regions (15.7% versus 17.0%, P CPR training and lower survival in regions with lower rates of bystander CPR in Victoria, Australia. Targeting these regions with CPR training programs may improve bystander CPR rates and out-of-hospital cardiac arrest outcomes. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  14. Damaging and protective bystander cross-talk between human lung cancer and normal cells after proton microbeam irradiation

    International Nuclear Information System (INIS)

    Desai, Sejal; Kobayashi, Alisa; Konishi, Teruaki; Oikawa, Masakazu; Pandey, Badri N.

    2014-01-01

    Graphical abstract: - Highlights: • Proton-microbeam irradiated A549 cells send damaging signals to bystander A549 cells. • Irradiated A549–A549 bystander response is through gap junctional communication. • Bystander WI38 cells exert protective signalling in irradiated A549 cells. • Rescue of irradiated A549 cells by WI38 cells is independent of gap junctions. - Abstract: Most of the studies of radiation-induced bystander effects (RIBE) have been focused on understanding the radiobiological changes observed in bystander cells in response to the signals from irradiated cells in a normal cell population with implications to radiation risk assessment. However, reports on RIBE with relevance to cancer radiotherapy especially investigating the bidirectional and criss-cross bystander communications between cancer and normal cells are limited. Hence, in present study employing co-culture approach, we have investigated the bystander cross-talk between lung cancer (A549) and normal (WI38) cells after proton-microbeam irradiation using γ-H2AX foci fluorescence as a measure of DNA double-strand breaks (DSBs). We observed that in A549–A549 co-cultures, irradiated A549 cells exert damaging effects in bystander A549 cells, which were found to be mediated through gap junctional intercellular communication (GJIC). However, in A549–WI38 co-cultures, irradiated A549 did not affect bystander WI38 cells. Rather, bystander WI38 cells induced inverse protective signalling (rescue effect) in irradiated A549 cells, which was independent of GJIC. On the other hand, in response to irradiated WI38 cells neither of the bystander cells (A549 or WI38) showed significant increase in γ-H2AX foci. The observed bystander signalling between tumour and normal cells may have potential implications in therapeutic outcome of cancer radiotherapy

  15. Damaging and protective bystander cross-talk between human lung cancer and normal cells after proton microbeam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Desai, Sejal [Radiation Signalling and Cancer Biology Section, Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kobayashi, Alisa; Konishi, Teruaki; Oikawa, Masakazu [Radiation System and Engineering Section, Department of Technical Support and Development, Research, Development and Support Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Pandey, Badri N., E-mail: badrinarain@yahoo.co.in [Radiation Signalling and Cancer Biology Section, Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2014-05-15

    Graphical abstract: - Highlights: • Proton-microbeam irradiated A549 cells send damaging signals to bystander A549 cells. • Irradiated A549–A549 bystander response is through gap junctional communication. • Bystander WI38 cells exert protective signalling in irradiated A549 cells. • Rescue of irradiated A549 cells by WI38 cells is independent of gap junctions. - Abstract: Most of the studies of radiation-induced bystander effects (RIBE) have been focused on understanding the radiobiological changes observed in bystander cells in response to the signals from irradiated cells in a normal cell population with implications to radiation risk assessment. However, reports on RIBE with relevance to cancer radiotherapy especially investigating the bidirectional and criss-cross bystander communications between cancer and normal cells are limited. Hence, in present study employing co-culture approach, we have investigated the bystander cross-talk between lung cancer (A549) and normal (WI38) cells after proton-microbeam irradiation using γ-H2AX foci fluorescence as a measure of DNA double-strand breaks (DSBs). We observed that in A549–A549 co-cultures, irradiated A549 cells exert damaging effects in bystander A549 cells, which were found to be mediated through gap junctional intercellular communication (GJIC). However, in A549–WI38 co-cultures, irradiated A549 did not affect bystander WI38 cells. Rather, bystander WI38 cells induced inverse protective signalling (rescue effect) in irradiated A549 cells, which was independent of GJIC. On the other hand, in response to irradiated WI38 cells neither of the bystander cells (A549 or WI38) showed significant increase in γ-H2AX foci. The observed bystander signalling between tumour and normal cells may have potential implications in therapeutic outcome of cancer radiotherapy.

  16. Joint Instability and Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Darryl Blalock

    2015-01-01

    Full Text Available Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA. Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA.

  17. Joint instability and osteoarthritis.

    Science.gov (United States)

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA.

  18. Characteristics and mechanisms of the bystander response in monolayer cell cultures exposed to very low fluences of alpha particles

    International Nuclear Information System (INIS)

    Little, John B.; Azzam, Edouard I.; Toledo, Sonia M. de; Nagasawa, Hatsumi

    2005-01-01

    When confluent cultures of mammalian cells are irradiated with very low fluences of alpha particles whereby only occasional cells receive any radiation exposure, genetic changes are observed in the non-irradiated ('bystander') cells. Upregulation of the p53 damage-response pathway as well as activation of proteins in the MAPK family occurred in bystander cells; p53 was phosphorylated on the serine 15 residue suggesting that the upregulation of p53 was a consequence of DNA damage. Damage signals were transmitted to bystander cells through gap junctions, as confirmed by the use of genetically manipulated cells including connexin43 knockouts. Expression of connexin43 was markedly enhanced by irradiation. A moderate bystander effect was observed for specific gene mutations and chromosomal aberrations. This effect was markedly enhanced in cells defective in the non-homologous end joining DNA repair pathway. Finally, an upregulation of oxidative metabolism occurred in bystander cells; the increased levels of reactive oxygen species appeared to be derived from flavine-containing oxidase enzymes. We hypothesize that genetic effects observed in non-irradiated bystander cells are a consequence of oxidative base damage; >90% of mutations in bystander cells were point mutations. When bystander cells cannot repair DNA double strand breaks, they become much more sensitive to the induction of chromosomal aberrations and mutations, the latter consisting primarily of deletion mutants. While we propose that the genetic effects occurring in bystander cells are a consequence of oxidative stress, the nature of the signal that initiates this process remains to be determined

  19. Evaluation of the Green Dot Bystander Intervention to Reduce Interpersonal Violence Among College Students Across Three Campuses

    Science.gov (United States)

    Coker, Ann L.; Fisher, Bonnie S.; Bush, Heather M.; Swan, Suzanne C.; Williams, Corrine M.; Clear, Emily R.; DeGue, Sarah

    2018-01-01

    Evidence suggests that interventions to engage bystanders in violence prevention increase bystander intentions and efficacy to intervene, yet the impact of such programs on violence remains unknown. This study compared rates of violence by type among undergraduate students attending a college campus with the Green Dot bystander intervention (n = 2,768) with students at two colleges without bystander programs (n = 4,258). Violent victimization rates were significantly (p Violence perpetration rates were lower among males attending the intervention campus. Implications of these results for research and practice are discussed. PMID:25125493

  20. Evaluation of the Green Dot Bystander Intervention to Reduce Interpersonal Violence Among College Students Across Three Campuses.

    Science.gov (United States)

    Coker, Ann L; Fisher, Bonnie S; Bush, Heather M; Swan, Suzanne C; Williams, Corrine M; Clear, Emily R; DeGue, Sarah

    2015-12-01

    Evidence suggests that interventions to engage bystanders in violence prevention increase bystander intentions and efficacy to intervene, yet the impact of such programs on violence remains unknown. This study compared rates of violence by type among undergraduate students attending a college campus with the Green Dot bystander intervention (n = 2,768) with students at two colleges without bystander programs (n = 4,258). Violent victimization rates were significantly (p < .01) lower among students attending the campus with Green Dot relative to the two comparison campuses. Violence perpetration rates were lower among males attending the intervention campus. Implications of these results for research and practice are discussed. © The Author(s) 2014.

  1. RAD9 deficiency enhances radiation induced bystander DNA damage and transcriptomal response

    International Nuclear Information System (INIS)

    Ghandhi, Shanaz A; Ponnaiya, Brian; Panigrahi, Sunil K; Hopkins, Kevin M; Cui, Qingping; Hei, Tom K; Amundson, Sally A; Lieberman, Howard B

    2014-01-01

    Radiation induced bystander effects are an important component of the overall response of cells to irradiation and are associated with human health risks. The mechanism responsible includes intra-cellular and inter-cellular signaling by which the bystander response is propagated. However, details of the signaling mechanism are not well defined. We measured the bystander response of Mrad9 +/+ and Mrad9 −/− mouse embryonic stem cells, as well as human H1299 cells with inherent or RNA interference-mediated reduced RAD9 levels after exposure to 1 Gy α particles, by scoring chromosomal aberrations and micronuclei formation, respectively. In addition, we used microarray gene expression analyses to profile the transcriptome of directly irradiated and bystander H1299 cells. We demonstrated that Mrad9 null enhances chromatid aberration frequency induced by radiation in bystander mouse embryonic stem cells. In addition, we found that H1299 cells with reduced RAD9 protein levels showed a higher frequency of radiation induced bystander micronuclei formation, compared with parental cells containing inherent levels of RAD9. The enhanced bystander response in human cells was associated with a unique transcriptomic profile. In unirradiated cells, RAD9 reduction broadly affected stress response pathways at the mRNA level; there was reduction in transcript levels corresponding to genes encoding multiple members of the UVA-MAPK and p38MAPK families, such as STAT1 and PARP1, suggesting that these signaling mechanisms may not function optimally when RAD9 is reduced. Using network analysis, we found that differential activation of the SP1 and NUPR1 transcriptional regulators was predicted in directly irradiated and bystander H1299 cells. Transcription factor prediction analysis also implied that HIF1α (Hypoxia induced factor 1 alpha) activation by protein stabilization in irradiated cells could be a negative predictor of the bystander response, suggesting that local hypoxic stress

  2. Single cell low dose studies of bystander cell killing with targeted ultrasoft x-rays

    International Nuclear Information System (INIS)

    Schettino, G.; Prise, K.M.; Folkard, M.; Vojnovic, B.; Michael, B.D.; Wu, L.; Held, K.D.

    2003-01-01

    Full text: Bystander responses have attracted considerable interest in the recent years and several investigations have reported a binary behavior with the effect triggered by very small doses and immediately reaching a plateau. The Ultrasoft X-ray Microprobe in operation at the GCI is a facility designed to precisely assess the biological response of individual cells in vitro irradiated with a sub-micron size X-ray beam . Although recent improvements have upgrade the facility with AlK and TiK X-rays, most of the bystander studies have been performed using CK X-rays of 278 eV. The high sensitivity and the accurate irradiation and revisiting of the individual samples allowed us to investigate specific characteristics of the bystander phenomenon. In particular, evidences of a dose dependency of cell killing by bystander effect have been found at doses below 0.2 Gy where no differences is observed between all cell and single cell irradiation. Recent improvements have also allowed us to individually identify the phase of the cell cycle of all samples exposed. Although the G2-S phase have been found the most sensitive in responding to the bystander signal (a factor of 1.3), cells in the G1 phase also respond significantly while the phase of the irradiated cell doesn't seem to play a critical role. The time scale of the bystander effect has also been investigated by irradiating the same sample(s) twice with a few hours gap between exposures. Results indicate that the bystander signal is transmitted within a few minutes from the irradiation as replacing the medium immediately after irradiation does not influence the response, and it doesn't depend on the number of cells irradiated (up to 5). However, after a resting time of a few hours (3 h), the system seems to reset itself and a second irradiation has been shown to trigger a further bystander effect. Finally, by considering the total amount of energy deposited in to the sample population as critical parameter (instead

  3. Hydrodynamic instabilities in inertial fusion

    International Nuclear Information System (INIS)

    Hoffman, N.M.

    1994-01-01

    This report discusses topics on hydrodynamics instabilities in inertial confinement: linear analysis of Rayleigh-Taylor instability; ablation-surface instability; bubble rise in late-stage Rayleigh-Taylor instability; and saturation and multimode interactions in intermediate-stage Rayleigh-Taylor instability

  4. Chromosomal Instability in Gastric Cancer Biology

    Directory of Open Access Journals (Sweden)

    Saffiyeh Saboor Maleki

    2017-05-01

    Full Text Available Gastric cancer (GC is the fifth most common cancer in the world and accounts for 7% of the total cancer incidence. The prognosis of GC is dismal in Western countries due to late diagnosis: approximately 70% of the patients die within 5 years following initial diagnosis. Recently, integrative genomic analyses led to the proposal of a molecular classification of GC into four subtypes, i.e.,microsatellite-instable, Epstein-Barr virus–positive, chromosomal-instable (CIN, and genomically stable GCs. Molecular classification of GC advances our knowledge of the biology of GC and may have implications for diagnostics and patient treatment. Diagnosis of microsatellite-instable GC and Epstein-Barr virus–positive GC is more or less straightforward. Microsatellite instability can be tested by immunohistochemistry (MLH1, PMS2, MSH2, and MSH6 and/or molecular-biological analysis. Epstein-Barr virus–positive GC can be tested by in situ hybridization (Epstein-Barr virus encoded small RNA. However, with regard to CIN, testing may be more complicated and may require a more in-depth knowledge of the underlying mechanism leading to CIN. In addition, CIN GC may not constitute a distinct subgroup but may rather be a compilation of a more heterogeneous group of tumors. In this review, we aim to clarify the definition of CIN and to point out the molecular mechanisms leading to this molecular phenotype and the challenges faced in characterizing this type of cancer.

  5. Bystander first aid in trauma - prevalence and quality: a prospective observational study.

    Science.gov (United States)

    Bakke, H K; Steinvik, T; Eidissen, S-I; Gilbert, M; Wisborg, T

    2015-10-01

    Bystander first aid and basic life support can likely improve victim survival in trauma. In contrast to bystander first aid and out-of-hospital cardiac arrest, little is known about the role of bystanders in trauma response. Our aim was to determine how frequently first aid is given to trauma victims by bystanders, the quality of this aid, the professional background of first-aid providers, and whether previous first-aid training affects aid quality. We conducted a prospective 18-month study in two mixed urban-rural Norwegian counties. The personnel on the first ambulance responding to trauma calls assessed and documented first aid performed by bystanders using a standard form. A total of 330 trauma calls were included, with bystanders present in 97% of cases. Securing an open airway was correctly performed for 76% of the 43 patients in need of this first-aid measure. Bleeding control was provided correctly for 81% of 63 patients for whom this measure was indicated, and prevention of hypothermia for 62% of 204 patients. Among the first-aid providers studied, 35% had some training in first aid. Bystanders with documented first-aid training gave better first aid than those where first-aid training status was unknown. A majority of the trauma patients studied received correct pre-hospital first aid, but still there is need for considerable improvement, particularly hypothermia prevention. Previous first-aid training seems to improve the quality of first aid provided. The effect on patient survival needs to be investigated. © 2015 The Authors. The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  6. Target irradiation induced bystander effects between stem-like and non stem-like cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yu [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Space Radiation Research Unit, International Open Laboratory, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Kobayashi, Alisa [Space Radiation Research Unit, International Open Laboratory, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Department of Technical Support and Development, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Maeda, Takeshi [Department of Technical Support and Development, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Fu, Qibin [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Oikawa, Masakazu [Department of Technical Support and Development, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Yang, Gen, E-mail: gen.yang@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Space Radiation Research Unit, International Open Laboratory, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Konishi, Teruaki, E-mail: tkonishi@nirs.go.jp [Space Radiation Research Unit, International Open Laboratory, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Department of Technical Support and Development, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Uchihori, Yukio [Space Radiation Research Unit, International Open Laboratory, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); Department of Technical Support and Development, National Institute of Radiological Sciences, 4-9-1 Inage-ku, Chiba 263-8555 (Japan); and others

    2015-03-15

    Highlights: • Existence of radiation induced bystander effects (RIBE) between cancer stem-like cells (CSCs) and non stem-like cancer cells (NSCCs) in human fibrosarcoma HT1080 cells. • Existence of significant difference in generation and response of bystander signals between CSCs and NSCCs. • CSCs are significantly less sensitive to NO scavenger than that of NSCCs in terms of DNA double strand breaks induced by RIBE. - Abstract: Tumors are heterogeneous in nature and consist of multiple cell types. Among them, cancer stem-like cells (CSCs) are suggested to be the principal cause of tumor metastasis, resistance and recurrence. Therefore, understanding the behavior of CSCs in direct and indirect irradiations is crucial for clinical radiotherapy. Here, the CSCs and their counterpart non stem-like cancer cells (NSCCs) in human HT1080 fibrosarcoma cell line were sorted and labeled, then the two cell subtypes were mixed together and chosen separately to be irradiated via a proton microbeam. The radiation-induced bystander effect (RIBE) between the CSCs and NSCCs was measured by imaging 53BP1 foci, a widely used indicator for DNA double strand break (DSB). CSCs were found to be less active than NSCCs in both the generation and the response of bystander signals. Moreover, the nitric oxide (NO) scavenger c-PTIO can effectively alleviate the bystander effect in bystander NSCCs but not in bystander CSCs, indicating a difference of the two cell subtypes in NO signal response. To our knowledge, this is the first report shedding light on the RIBE between CSCs and NSCCs, which might contribute to a further understanding of the out-of-field effect in cancer radiotherapy.

  7. Target irradiation induced bystander effects between stem-like and non stem-like cancer cells

    International Nuclear Information System (INIS)

    Liu, Yu; Kobayashi, Alisa; Maeda, Takeshi; Fu, Qibin; Oikawa, Masakazu; Yang, Gen; Konishi, Teruaki; Uchihori, Yukio

    2015-01-01

    Highlights: • Existence of radiation induced bystander effects (RIBE) between cancer stem-like cells (CSCs) and non stem-like cancer cells (NSCCs) in human fibrosarcoma HT1080 cells. • Existence of significant difference in generation and response of bystander signals between CSCs and NSCCs. • CSCs are significantly less sensitive to NO scavenger than that of NSCCs in terms of DNA double strand breaks induced by RIBE. - Abstract: Tumors are heterogeneous in nature and consist of multiple cell types. Among them, cancer stem-like cells (CSCs) are suggested to be the principal cause of tumor metastasis, resistance and recurrence. Therefore, understanding the behavior of CSCs in direct and indirect irradiations is crucial for clinical radiotherapy. Here, the CSCs and their counterpart non stem-like cancer cells (NSCCs) in human HT1080 fibrosarcoma cell line were sorted and labeled, then the two cell subtypes were mixed together and chosen separately to be irradiated via a proton microbeam. The radiation-induced bystander effect (RIBE) between the CSCs and NSCCs was measured by imaging 53BP1 foci, a widely used indicator for DNA double strand break (DSB). CSCs were found to be less active than NSCCs in both the generation and the response of bystander signals. Moreover, the nitric oxide (NO) scavenger c-PTIO can effectively alleviate the bystander effect in bystander NSCCs but not in bystander CSCs, indicating a difference of the two cell subtypes in NO signal response. To our knowledge, this is the first report shedding light on the RIBE between CSCs and NSCCs, which might contribute to a further understanding of the out-of-field effect in cancer radiotherapy

  8. Differential Bystander Signaling Between Radioresistant Chondrosarcoma Cells and Fibroblasts After X-Ray, Proton, Iron Ion and Carbon Ion Exposures

    Energy Technology Data Exchange (ETDEWEB)

    Wakatsuki, Masaru, E-mail: wa@mbe.nifty.com [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Department of Radiation Oncology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts (United States); Magpayo, Nicole; Kawamura, Hidemasa; Held, Kathryn D. [Department of Radiation Oncology, Massachusetts General Hospital/Harvard Medical School, Boston, Massachusetts (United States)

    2012-09-01

    Purpose: Chondrosarcoma is well known as a radioresistant tumor, but the mechanisms underlying that resistance are still unclear. The bystander effect is well documented in the field of radiation biology. We investigated the bystander response induced by X-rays, protons, carbon ions, and iron ions in chondrosarcoma cells using a transwell insert co-culture system that precludes physical contact between targeted and bystander cells. Methods and Materials: Human chondrosarcoma cells were irradiated with 0.1-, 0.5-, 1-, and 2-Gy X-rays, protons, carbon ions or iron ions using a transwell insert co-culture system. Formation of micronuclei and p53 binding protein 1 staining in bystander and irradiated cells were analyzed and bystander signaling between mixed cultures of chondrosarcoma cells, and normal human skin fibroblasts was investigated. Results: In this study, we show that the fraction of cells with DNA damages in irradiated chondrosarcoma cells showed dose-dependent increases with all beams. However, the fraction of cells with DNA damages in all bystander