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Sample records for ionizing radiation resistance

  1. Bacterial and archaeal resistance to ionizing radiation

    NASA Astrophysics Data System (ADS)

    Confalonieri, F.; Sommer, S.

    2011-01-01

    Organisms living in extreme environments must cope with large fluctuations of temperature, high levels of radiation and/or desiccation, conditions that can induce DNA damage ranging from base modifications to DNA double-strand breaks. The bacterium Deinococcus radiodurans is known for its resistance to extremely high doses of ionizing radiation and for its ability to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Recently, extreme ionizing radiation resistance was also generated by directed evolution of an apparently radiation-sensitive bacterial species, Escherichia coli. Radioresistant organisms are not only found among the Eubacteria but also among the Archaea that represent the third kingdom of life. They present a set of particular features that differentiate them from the Eubacteria and eukaryotes. Moreover, Archaea are often isolated from extreme environments where they live under severe conditions of temperature, pressure, pH, salts or toxic compounds that are lethal for the large majority of living organisms. Thus, Archaea offer the opportunity to understand how cells are able to cope with such harsh conditions. Among them, the halophilic archaeon Halobacterium sp and several Pyrococcus or Thermococcus species, such as Thermococcus gammatolerans, were also shown to display high level of radiation resistance. The dispersion, in the phylogenetic tree, of radioresistant prokaryotes suggests that they have independently acquired radioresistance. Different strategies were selected during evolution including several mechanisms of radiation byproduct detoxification and subtle cellular metabolism modifications to help cells recover from radiation-induced injuries, protection of proteins against oxidation, an efficient DNA repair tool box, an original pathway of DNA double-strand break repair, a condensed nucleoid that may prevent the dispersion of the DNA fragments and specific radiation-induced proteins involved in

  2. Extreme Ionizing-Radiation-Resistant Bacterium

    NASA Technical Reports Server (NTRS)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2013-01-01

    There is a growing concern that desiccation and extreme radiation-resistant, non-spore-forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequent proliferation on another solar body. Such forward contamination would jeopardize future life detection or sample return technologies. The prime focus of NASA s planetary protection efforts is the development of strategies for inactivating resistance-bearing micro-organisms. Eradi cation techniques can be designed to target resistance-conferring microbial populations by first identifying and understanding their physiologic and biochemical capabilities that confers its elevated tolerance (as is being studied in Deinococcus phoenicis, as a result of this description). Furthermore, hospitals, food, and government agencies frequently use biological indicators to ensure the efficacy of a wide range of radiation-based sterilization processes. Due to their resistance to a variety of perturbations, the nonspore forming D. phoenicis may be a more appropriate biological indicator than those currently in use. The high flux of cosmic rays during space travel and onto the unshielded surface of Mars poses a significant hazard to the survival of microbial life. Thus, radiation-resistant microorganisms are of particular concern that can survive extreme radiation, desiccation, and low temperatures experienced during space travel. Spore-forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate these extreme conditions. Since the Viking era, spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. Members of the non-sporeforming bacterial community such as Deinococcus radiodurans can survive acute exposures to ionizing radiation (5 kGy), ultraviolet light (1 kJ/m2), and desiccation (years). These resistive phenotypes of Deinococcus enhance the

  3. Extreme Ionizing-Radiation-Resistant Bacterium

    NASA Technical Reports Server (NTRS)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2012-01-01

    There is a growing concern that desiccation and extreme radiation-resistant, non-spore-forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequent proliferation on another solar body. Such forward contamination would jeopardize future life detection or sample return technologies. The prime focus of NASA s planetary protection efforts is the development of strategies for inactivating resistance-bearing microorganisms. Eradification techniques can be designed to target resistance-conferring microbial populations by first identifying and understanding their physiologic and biochemical capabilities that confers its elevated tolerance (as is being studied in Deinococcus phoenicis, as a result of this description). Furthermore, hospitals, food, and government agencies frequently use biological indicators to ensure the efficacy of a wide range of radiation- based sterilization processes. Due to their resistance to a variety of perturbations, the non-spore forming D. phoenicis may be a more appropriate biological indicator than those currently in use. The high flux of cosmic rays during space travel and onto the unshielded surface of Mars poses a significant hazard to the survival of microbial life. Thus, radiation-resistant microorganisms are of particular concern that can survive extreme radiation, desiccation, and low temperatures experienced during space travel. Spore-forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate these extreme conditions. Since the Viking era, spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. Members of the non-spore-forming bacterial community such as Deinococcus radiodurans can survive acute exposures to ionizing radiation (5 kGy), ultraviolet light (1 kJ/sq m), and desiccation (years). These resistive phenotypes of Deinococcus enhance the

  4. Genetic variation in resistance to ionizing radiation

    SciTech Connect

    Ayala, F.J.

    1989-01-01

    The very reactive superoxide anion O[sub 2] is generated during cell respiration as well as during exposure to ionizing radiation. Organisms have evolved different mechanisms to protect against the deleterious effects of reduced oxygen species. The copper-zinc superoxide dismutase is a eukaryotic cytoplasmic enzyme that protects the cell by scavenging superoxide radicals and dismutating them to hydrogen peroxide and molecular oxygen: 20[sub 2][sup [minus

  5. Genetic variation in resistance to ionizing radiation

    SciTech Connect

    Ayala, F.J.

    1991-06-24

    We proposed an investigation of genetically-determined individual differences in sensitivity to ionizing radiation. The model organism is Drosophila melanogaster. The gene coding for Cu,Zn superoxide dismutase (SOD) is the target locus, but the effects of variation in other components of the genome that modulate SOD levels are also taken into account. SOD scavenges oxygen radicals generated during exposure to ionizing radiation. It has been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Two alleles, S and F, are commonly found in natural populations of D. melanogaster; in addition we have isolated from a natural population null'' (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide an ideal model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CA1. The roles of SOD level in radioresistance are being investigated in a series of experiments that measure the somatic and germ-line effects of increasing doses of ionizing radiation. In addition, we have pursued an unexpected genetic event-namely the nearly simultaneous transformation of several lines homozygous for the SOD null'' allele into predominately S lines. Using specifically designed probes and DNA amplification by means of the Tag polymerase chain reaction (PCR) we have shown that (1) the null allele was still present in the transformed lines, but was being gradually replaced by the S allele as a consequence of natural selection; and (2) that the transformation was due to the spontaneous deletion of a 0.68 Kb truncated P-element, the insertion of which is characteristic of the CA1 null allele.

  6. The extreme ionizing radiation resistance of Deinoccus radiodurans

    SciTech Connect

    Battista, J.R.

    1996-10-01

    The bacterium Deinococcus radiodurans is distinguished by its extraordinary resistance to the lethal and mutagenic effects of ionizing radiation, withstanding doses as high as 5000 Gy without loss of viability. The capacity to survive such massive insults to their genetic integrity suggests that this organism has evolved distinctive mechanisms of DNA damage tolerance and available evidence argues that efficient DNA repair is an integral part of this tolerance. The enzymology of deinococcal DNA repair processes is poorly understood, however. This talk will discuss recent genetic and biochemical studies of several ionizing radiation sensitive strains of D. radiodurans that reveal that D. radiodurans employs a complex strategy for repairing DNA damage that relies on multiple redundant repair pathways. There are, for example, two equally efficient systems for repairing ionizing radiation-induced DNA damage and it requires mutational inactivation of both systems to render the cell ionizing radiation resistant.

  7. Genetic variation in resistance to ionizing radiation

    SciTech Connect

    Ayala, F.J.

    1992-01-01

    Results of an investigation of the gene coding for Cu, Zn superoxide dismutase (Sod) in Drosophila melanogaster seeking to understand the enzyme's role in cell protection against ionizing radiation are reported. Components of the investigation include molecular characterization of the gene; measuring the response of different genotypes to increasing levels of radiation; and investigation of the processes that maintain the Sod polymorphism in populations. While two alleles, S and F, are commonly found at the Sod locus in natural populations of D. melanogaster we have isolated from a natural population a null (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide a model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CAl. The radioprotective effects of SOD can be established by showing protective effects for the various genotypes that correspond to those inequalities. Because the allele variants studied are derived from natural populations, the proposed investigation avoids problems that arise when mutants obtained my mutagenesis are used. Moreover, each allele is studied in multiple genetic backgrounds, so that we correct for effects attributable to other loci by randomizing these effects.

  8. Genetic variation in resistance to ionizing radiation. [Annual report, 1989

    SciTech Connect

    Ayala, F.J.

    1989-12-31

    The very reactive superoxide anion O{sub 2} is generated during cell respiration as well as during exposure to ionizing radiation. Organisms have evolved different mechanisms to protect against the deleterious effects of reduced oxygen species. The copper-zinc superoxide dismutase is a eukaryotic cytoplasmic enzyme that protects the cell by scavenging superoxide radicals and dismutating them to hydrogen peroxide and molecular oxygen: 20{sub 2}{sup {minus}} + 2H {yields} H{sub 2}O{sub 2} + O{sub 2}. SOD had been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Evidence that genetic differences may affect sensitivity to ionizing radiation has been shown in Drosophila since differences have been shown to exist between strains and resistance to radiation can evolve under natural selection.

  9. Directed Evolution of Ionizing Radiation Resistance in Escherichia coli▿ †

    PubMed Central

    Harris, Dennis R.; Pollock, Steve V.; Wood, Elizabeth A.; Goiffon, Reece J.; Klingele, Audrey J.; Cabot, Eric L.; Schackwitz, Wendy; Martin, Joel; Eggington, Julie; Durfee, Timothy J.; Middle, Christina M.; Norton, Jason E.; Popelars, Michael C.; Li, Hao; Klugman, Sarit A.; Hamilton, Lindsay L.; Bane, Lukas B.; Pennacchio, Len A.; Albert, Thomas J.; Perna, Nicole T.; Cox, Michael M.; Battista, John R.

    2009-01-01

    We have generated extreme ionizing radiation resistance in a relatively sensitive bacterial species, Escherichia coli, by directed evolution. Four populations of Escherichia coli K-12 were derived independently from strain MG1655, with each specifically adapted to survive exposure to high doses of ionizing radiation. D37 values for strains isolated from two of the populations approached that exhibited by Deinococcus radiodurans. Complete genomic sequencing was carried out on nine purified strains derived from these populations. Clear mutational patterns were observed that both pointed to key underlying mechanisms and guided further characterization of the strains. In these evolved populations, passive genomic protection is not in evidence. Instead, enhanced recombinational DNA repair makes a prominent but probably not exclusive contribution to genome reconstitution. Multiple genes, multiple alleles of some genes, multiple mechanisms, and multiple evolutionary pathways all play a role in the evolutionary acquisition of extreme radiation resistance. Several mutations in the recA gene and a deletion of the e14 prophage both demonstrably contribute to and partially explain the new phenotype. Mutations in additional components of the bacterial recombinational repair system and the replication restart primosome are also prominent, as are mutations in genes involved in cell division, protein turnover, and glutamate transport. At least some evolutionary pathways to extreme radiation resistance are constrained by the temporally ordered appearance of specific alleles. PMID:19502398

  10. Extreme resistance of bdelloid rotifers to ionizing radiation

    PubMed Central

    Gladyshev, Eugene; Meselson, Matthew

    2008-01-01

    Rotifers of class Bdelloidea are common invertebrate animals with highly unusual characteristics, including apparently obligate asexuality, the ability to resume reproduction after desiccation at any life stage, and a paucity of transposable genetic elements of types not prone to horizontal transmission. We find that bdelloids are also extraordinarily resistant to ionizing radiation (IR). Reproduction of the bdelloids Adineta vaga and Philodina roseola is much more resistant to IR than that of Euchlanis dilatata, a rotifer belonging to the desiccation-intolerant and facultatively sexual class Monogononta, and all other animals for which we have found relevant data. By analogy with the desiccation- and radiation-resistant bacterium Deinococcus radiodurans, we suggest that the extraordinary radiation resistance of bdelloid rotifers is a consequence of their evolutionary adaptation to survive episodes of desiccation encountered in their characteristic habitats and that the damage incurred in such episodes includes DNA breakage that is repaired upon rehydration. Such breakage and repair may have maintained bdelloid chromosomes as colinear pairs and kept the load of transposable genetic elements low and may also have contributed to the success of bdelloid rotifers in avoiding the early extinction suffered by most asexuals. PMID:18362355

  11. Down-regulation of PERK enhances resistance to ionizing radiation

    SciTech Connect

    Oommen, Deepu Prise, Kevin M.

    2013-11-08

    Highlights: •PERK enhances the sensitivity of cancer cells to ionizing radiation. •Down-regulation of PERK results in enhanced DNA repair. •Ionizing radiation-induced apoptosis is inhibited in PERK-down regulated cancer cells. -- Abstract: Although, ionizing radiation (IR) has been implicated to cause stress in endoplasmic reticulum (ER), how ER stress signaling and major ER stress sensors modulate cellular response to IR is unclear. Protein kinase RNA-like endoplasmic reticulum kinase (PERK) is an ER transmembrane protein which initiates unfolded protein response (UPR) or ER stress signaling when ER homeostasis is disturbed. Here, we report that down-regulation of PERK resulted in increased clonogenic survival, enhanced DNA repair and reduced apoptosis in irradiated cancer cells. Our study demonstrated that PERK has a role in sensitizing cancer cells to IR.

  12. Ionizing radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter gives a comprehensive review on ionizing irradiation of fresh fruits and vegetables. Topics include principles of ionizing radiation, its effects on pathogenic and spoilage microorganisms, shelf-life, sensory quality, nutritional and phytochemical composition, as well as physiologic and...

  13. Resistance of platelet proteins to effects of ionizing radiation

    SciTech Connect

    Prodouz, K.N.; Habraken, J.W.; Moroff, G. )

    1990-12-01

    Gamma irradiation of blood components prevents lymphocyte-induced graft-versus-host disease after transfusion in immunocompromised individuals. In this report we demonstrate the resistance of blood platelet proteins to gamma radiation-induced protein cleavage and aggregate formation when platelet concentrates were treated with a dose of 5000 rad. Results of one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total platelet protein and cytoskeletal protein preparations indicate that platelet proteins are neither cleaved nor cross-linked under these conditions of irradiation. These results support those of a previous study that documented the lack of any adverse effect of 5000 rad gamma radiation on in vitro platelet properties.

  14. Identifying the Proteins that Mediate the Ionizing Radiation Resistance of Deinococcus Radiodurans R1

    SciTech Connect

    Battista, John R

    2010-02-22

    The primary objectives of this proposal was to define the subset of proteins required for the ionizing radiation (IR) resistance of Deinococcus radiodurans R1, characterize the activities of those proteins, and apply what was learned to problems of interest to the Department of Energy.

  15. Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl

    PubMed Central

    Ruiz-González, Mario Xavier; Czirják, Gábor Árpád; Genevaux, Pierre; Møller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

    2016-01-01

    Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different γ radiation doses ranging from 0.46 to 3.96 kGy to test whether chronic exposure to radiation had selected for resistant bacterial strains. Experimental radiation duration had an increasingly overall negative effect on the survival of all bacterial communities. After exposure to γ radiation, bacteria isolated from the site with intermediate background radiation levels survived better and produced more colonies than the bacterial communities from other study sites with higher or lower background radiation levels. Long-term effects of radiation in natural populations might be an important selective pressure on traits of bacteria that facilitate survival in certain environments. Our findings indicate the importance of further studies to understand the proximate mechanisms acting to buffer the negative effects of ionizing radiation in natural populations. PMID:26976674

  16. Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl.

    PubMed

    Ruiz-González, Mario Xavier; Czirják, Gábor Árpád; Genevaux, Pierre; Møller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

    2016-01-01

    Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different γ radiation doses ranging from 0.46 to 3.96 kGy to test whether chronic exposure to radiation had selected for resistant bacterial strains. Experimental radiation duration had an increasingly overall negative effect on the survival of all bacterial communities. After exposure to γ radiation, bacteria isolated from the site with intermediate background radiation levels survived better and produced more colonies than the bacterial communities from other study sites with higher or lower background radiation levels. Long-term effects of radiation in natural populations might be an important selective pressure on traits of bacteria that facilitate survival in certain environments. Our findings indicate the importance of further studies to understand the proximate mechanisms acting to buffer the negative effects of ionizing radiation in natural populations. PMID:26976674

  17. Diversity of ionizing radiation-resistant bacteria obtained from the Taklimakan Desert.

    PubMed

    Yu, Li Zhi-Han; Luo, Xue-Song; Liu, Ming; Huang, Qiaoyun

    2015-01-01

    So far, little is known about the diversity of the radiation-resistant microbes of the hyperarid Taklimakan Desert. In this study, ionizing radiation (IR)-resistant bacteria from two sites in Xinjiang were investigated. After exposing the arid (water content of 0.8 ± 0.3%) and non-arid (water content of 21.3 ± 0.9%) sediment samples to IR of 3000 Gy using a (60)Co source, a total of 52 γ-radiation-resistant bacteria were isolated from the desert sample. The 16S rRNA genes of all isolates were sequenced. The phylogenetic tree places these isolates into five groups: Cytophaga-Flavobacterium-Bacteroides, Proteobacteria, Deinococcus-Thermus, Firmicutes, and Actinobacteria. Interestingly, this is the first report of radiation-resistant bacteria belonging to the genera Knoellia, Lysobacter, Nocardioides, Paracoccus, Pontibacter, Rufibacter and Microvirga. The 16s rRNA genes of four isolates showed low sequence similarities to those of the published species. Phenotypic analysis showed that all bacteria in this study are able to produce catalase, suggesting that these bacteria possess reactive oxygen species (ROS)-scavenging enzymes. These radiation-resistant bacteria also displayed diverse metabolic properties. Moreover, their radiation resistances were found to differ. The diversity of the radiation-resistant bacteria in the desert provides further ecological support for the hypothesis that the ionizing-radiation resistance phenotype is a consequence of the evolution of ROS-scavenging systems that protect cells against oxidative damage caused by desiccation. PMID:25590873

  18. Nalidixic acid resistance influences sensitivity to ionizing radiation among Salmonella isolates.

    PubMed

    Niemira, Brendan A; Lonczynski, Kelly A

    2006-07-01

    Nalidixic acid (Nal) resistance has been used as a selective marker for studies of pathogen-inoculated fruits and vegetables. A collection of 24 Salmonella isolates were screened for natural resistance to Nal (50 microg/ml). The resistance to ionizing radiation was determined and compared for i) three naturally Nal-resistant (Nal(R)) strains, ii) three naturally Nal-sensitive (Nal(S)) strains, and iii) three strains derived from Nals strains that were made resistant to Nal (Nal(Ri)) by successive culturing and selection in Nal-amended broth. The radiation D10-values (the radiation dose required to achieve a 1-log reduction in population) were determined in buffer solution and in orange juice. D10-values were significantly (P < 0.05) different among the Salmonella isolates tested. When considered as a group, Nal(R) isolates were significantly more sensitive to ionizing radiation than Nals isolates in both media tested. In buffer, D10 of Nal(R) was 0.210 kGy versus 0.257 kGy for Nals. In orange juice, D10 of Nal(R) was 0.581 versus 0.764 for Nals. Inducing resistance to Nal altered the response to irradiation. D10-value of Nal(Ri) was 0.234 kGy in buffer, a 9% reduction relative to Nals parents. In orange juice, the D10-value of Nal(Ri) was 0.637 kGy, a reduction of 17% relative to Nals parents. These results suggest that natural and/or induced resistance to Nal may predispose Salmonella isolates to greater sensitivity to ionizing radiation,and that this effect is influenced by the suspending medium and by the nature of the isolates evaluated. PMID:16865890

  19. Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels

    PubMed Central

    Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

    2011-01-01

    Background The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. Methodology/Principal Findings To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Conclusions/Significance Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general

  20. Low-Temperature Ionizing Radiation Resistance of Deinococcus radiodurans and Antarctic Dry Valley Bacteria

    NASA Astrophysics Data System (ADS)

    Dartnell, Lewis R.; Hunter, Stephanie J.; Lovell, Keith V.; Coates, Andrew J.; Ward, John M.

    2010-09-01

    The high flux of cosmic rays onto the unshielded surface of Mars poses a significant hazard to the survival of martian microbial life. Here, we determined the survival responses of several bacterial strains to ionizing radiation exposure while frozen at a low temperature characteristic of the martian near-subsurface. Novel psychrotolerant bacterial strains were isolated from the Antarctic Dry Valleys, an environmental analogue of the martian surface, and identified by 16S rRNA gene phylogeny as representatives of Brevundimonas, Rhodococcus, and Pseudomonas genera. These isolates, in addition to the known radioresistant extremophile Deinococcus radiodurans, were exposed to gamma rays while frozen on dry ice (-79°C). We found D. radiodurans to exhibit far greater radiation resistance when irradiated at -79°C than was observed in similar studies performed at higher temperatures. This greater radiation resistance has important implications for the estimation of potential survival times of microorganisms near the martian surface. Furthermore, the most radiation resistant of these Dry Valley isolates, Brevundimonas sp. MV.7, was found to show 99% 16S rRNA gene similarity to contaminant bacteria discovered in clean rooms at both Kennedy and Johnson Space Centers and so is of prime concern to efforts in the planetary protection of Mars from our lander probes. Results from this experimental irradiation, combined with previous radiation modeling, indicate that Brevundimonas sp. MV.7 emplaced only 30 cm deep in martian dust could survive the cosmic radiation for up to 100,000 years before suffering 106 population reduction.

  1. RAD18 mediates resistance to ionizing radiation in human glioma cells

    SciTech Connect

    Xie, Chen; Wang, Hongwei; Cheng, Hongbin; Li, Jianhua; Wang, Zhi Yue, Wu

    2014-02-28

    Highlights: • RAD18 is an important mediator of the IR-induced resistance in glioma cell lines. • RAD18 overexpression confers resistance to IR-mediated apoptosis. • The elevated expression of RAD18 is associated with recurrent GBM who underwent IR therapy. - Abstract: Radioresistance remains a major challenge in the treatment of glioblastoma multiforme (GBM). RAD18 a central regulator of translesion DNA synthesis (TLS), has been shown to play an important role in regulating genomic stability and DNA damage response. In the present study, we investigate the relationship between RAD18 and resistance to ionizing radiation (IR) and examined the expression levels of RAD18 in primary and recurrent GBM specimens. Our results showed that RAD18 is an important mediator of the IR-induced resistance in GBM. The expression level of RAD18 in glioma cells correlates with their resistance to IR. Ectopic expression of RAD18 in RAD18-low A172 glioma cells confers significant resistance to IR treatment. Conversely, depletion of endogenous RAD18 in RAD18-high glioma cells sensitized these cells to IR treatment. Moreover, RAD18 overexpression confers resistance to IR-mediated apoptosis in RAD18-low A172 glioma cells, whereas cells deficient in RAD18 exhibit increased apoptosis induced by IR. Furthermore, knockdown of RAD18 in RAD18-high glioma cells disrupts HR-mediated repair, resulting in increased accumulation of DSB. In addition, clinical data indicated that RAD18 was significantly higher in recurrent GBM samples that were exposed to IR compared with the corresponding primary GBM samples. Collectively, our findings reveal that RAD18 may serve as a key mediator of the IR response and may function as a potential target for circumventing IR resistance in human GBM.

  2. Ionizing radiation-induced 6-thioguanine-resistant clones in synchronous CHO cells

    SciTech Connect

    Burki, J.

    1980-01-01

    When cultured Chinese hamster ovary (CHO) cells are exposed to acute doses of ionizing radiation at different times during the cell division cycle, there is a characteristic cell-cycle response for radiation-induced cell killing and induced resistance to 6-thio-guanine (6TG). For cell killing the sensitive periods of the cell cycle are the G1, G2, M, and early S periods, as others have reported. For mutation induction the sensitive stage is the G1 period with the maximum sensitivity near the boundary between the G1 and the S period. Cells appear to be very refractile to induction of 6TG resistance in other periods of the cell cycle. These results suggest that chromosomal rearrangements of the X chromosome are most likely to occur in the G1 period before the gene for hypoxanthine-guanine-phosphoribosyl-transferase replicates, most likely due to genetic recombination. Clones resistant to 6TG after exposure to x rays are most likely induced by a different mutagenic pathway than ones stimulated by ultraviolet (uv) or ethylnitrosourea treatments, since the mutation induction patterns in the cell cycle are quite different.

  3. β1 integrins mediate resistance to ionizing radiation in vivo by inhibiting c-Jun amino terminal kinase 1

    PubMed Central

    Goel, Hira Lal; Sayeed, Aejaz; Breen, Michael; Zarif, Matthew J.; Garlick, David S.; Leav, Irwin; Davis, Roger J.; FitzGerald, Thomas J.; Morrione, Andrea; Hsieh, Chung-Cheng; Liu, Qin; Dicker, Adam P.; Altieri, Dario C.; Languino, Lucia R.

    2013-01-01

    This study was carried out to dissect the mechanism by which β1 integrins promote resistance to radiation. For this purpose, we conditionally ablated β1 integrins in the prostatic epithelium of transgenic adenocarcinoma of mouse prostate (TRAMP) mice. The ability of β1 to promote resistance to radiation was also analyzed by using an inhibitory antibody to β1, AIIB2, in a xenograft model. The role of β1 integrins and of a β1 downstream target, c-Jun amino-terminal kinase 1 (JNK1), in regulating radiation-induced apoptosis in vivo and in vitro was studied. We show that β1 integrins promote prostate cancer (PrCa) progression and resistance to radiation in vivo. Mechanistically, β1 integrins are shown here to suppress activation of JNK1 and, consequently apoptosis, in response to irradiation. Downregulation of JNK1 is necessary to preserve the effect of β1 on resistance to radiation in vitro and in vivo. Finally, given the established cross-talk between β1 integrins and type 1 insulin-like growth factor receptor (IGF-IR), we analyzed the ability of IGF-IR to modulate β1 integrin levels. We report that IGF-IR regulates the expression of β1 integrins, which in turn confer resistance to radiation in PrCa cells. In conclusion, this study demonstrates that β1 integrins mediate resistance to ionizing radiation through inhibition of JNK1 activation. PMID:23359252

  4. Biological Effects of Ionizing Radiation

    DOE R&D Accomplishments Database

    Ingram, M.; Mason, W. B.; Whipple, G. H.; Howland, J. W.

    1952-04-07

    This report presents a review of present knowledge and concepts of the biological effects of ionizing radiations. Among the topics discussed are the physical and chemical effects of ionizing radiation on biological systems, morphological and physiological changes observed in biological systems subjected to ionizing radiations, physiological changes in the intact animal, latent changes following exposure of biological systems to ionizing radiations, factors influencing the biological response to ionizing radiation, relative effects of various ionizing radiations, and biological dosimetry.

  5. Genetic variation in resistance to ionizing radiation. Technical progress report, January--December 1991

    SciTech Connect

    Ayala, F.J.

    1991-06-24

    We proposed an investigation of genetically-determined individual differences in sensitivity to ionizing radiation. The model organism is Drosophila melanogaster. The gene coding for Cu,Zn superoxide dismutase (SOD) is the target locus, but the effects of variation in other components of the genome that modulate SOD levels are also taken into account. SOD scavenges oxygen radicals generated during exposure to ionizing radiation. It has been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Two alleles, S and F, are commonly found in natural populations of D. melanogaster; in addition we have isolated from a natural population ``null`` (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide an ideal model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CA1. The roles of SOD level in radioresistance are being investigated in a series of experiments that measure the somatic and germ-line effects of increasing doses of ionizing radiation. In addition, we have pursued an unexpected genetic event-namely the nearly simultaneous transformation of several lines homozygous for the SOD ``null`` allele into predominately S lines. Using specifically designed probes and DNA amplification by means of the Tag polymerase chain reaction (PCR) we have shown that (1) the null allele was still present in the transformed lines, but was being gradually replaced by the S allele as a consequence of natural selection; and (2) that the transformation was due to the spontaneous deletion of a 0.68 Kb truncated P-element, the insertion of which is characteristic of the CA1 null allele.

  6. Ionizing radiations induce apoptosis in TRAIL resistant cancer cells: in vivo and in vitro analysis.

    PubMed

    Silva, Marcela Fernandes; Khokhar, Abdur Rehman; Qureshi, Muhammad Zahid; Farooqi, Ammad Ahmad

    2014-01-01

    Increasingly it is being realized that despite considerable advancements in therapeutic interventions related to treatment of cancer, satisfactory results are still difficult to achieve. Rapidly accumulating evidence has started to shed light on the fact that cancer cells escape from death via constitutive activation of pro-survival signaling cascades. Cell biology and genetics have extensively enhanced our current understanding of the molecular mechanisms that underlie loss of apoptosis in cancer cells. This review is focused on ionizing radiation mediated restoration of TRAIL mediated apoptosis as evidenced by cell culture and animal model studies. Moreover, we also bring to the limelight radiation induced expression of miRNAs and how miRNAs further control response of cancer cells to radiation. PMID:24716909

  7. Complete genome sequence of ionizing radiation-resistant Hymenobacter sp. strain PAMC26628 isolated from an Arctic lichen.

    PubMed

    Ahn, Do-Hwan; Han, So-Ra; Oh, Tae-Jin; Park, Hyun

    2016-04-10

    Ionizing radiation-resistant Hymenobacter sp. strain PAMC26628 was isolated from Stereocaulon sp., an Arctic lichen. Complete genome sequencing of Hymenobacter sp. PAMC26628 revealed one chromosome (5,277,381bp), one plasmid (89,596bp), and several genes involved in nucleotide excision repair, a DNA damage removal pathway. An analysis of the Hymenobacter sp. PAMC26628 genome will help us understand its evolution and provide novel insight into the adaptations that allow this organism to survive in the extreme cold of the Arctic. PMID:26924242

  8. Determinants of resistance to chemotherapy and ionizing radiation in breast cancer stem cells.

    PubMed

    Pavlopoulou, Athanasia; Oktay, Yavuz; Vougas, Konstantinos; Louka, Maria; Vorgias, Constantinos E; Georgakilas, Alexandros G

    2016-10-01

    Breast cancer cells are suggested to be organized in a hierarchical manner with a subpopulation of stem cells, termed as breast cancer stem cells (BCSCs), which contribute significantly to tumorigenesis, cancer recurrence and metastasis. BCSCs have been demonstrated to exhibit significant resistance to conventional chemo- and radiotherapy. Recent evidence suggests that treatment of breast cancers with radiation or chemotherapy agents induces stem cell-like properties in non-stem cells. Herein, we provide an overview of the key determinants of resistance to chemotherapy and radiation in BCSCs. To this end and by the use of bioinformatics, the molecular pathways, the defining markers, as well as the microenvironmental and genetic factors, which are implicated in the maintenance of stemness, chemo- and radioresistance in BCSCs, are identified and presented. Our findings could provide the foundation for the design of targeted chemo- or radiotherapeutic regimens in order to eliminate or sensitize BCSCs to cytotoxic therapies and prevent tumor relapse and metastasis. PMID:27450721

  9. Genetic network profiles associated with established resistance to ionizing radiation in acute promyelocytic leukemia cells and their extracellular vesicles.

    PubMed

    Monzen, Satoru; Chiba, Mitsuru; Hosokawa, Yoichiro

    2016-02-01

    Radiation-resistant acute promyelocytic leukemia (APL) cells present challenges to treatment, and the acquisition of resistance to ionizing radiation (IR) is a matter of clinical concern. However, little information is available on the behavior of radio-resistant APL in terms of gene expression profiles and intercellular communication. In this study, cDNA microarray and RT-PCR were used to analyze the intracellular genetic network and extracellular vesicles (EVs), respectively, in the established radio-resistant HL60 (Res-HL60) cell line. Significant changes in the expression of 7,309 known mRNAs were observed in Res-HL60 relative to control. In addition, 7 mRNAs were determined as targets because significant changes in the expression were observed using Ingenuity analysis software, confirming the quantitative RT-PCR. However, EVs from Res-HL60 cells did not include these target molecules. These results suggest that radio-resistant APL is regulated by the expression and suppression of specific molecules, and these molecules are not transferred between cells by EVs. PMID:26718911

  10. Genetic variation in resistance to ionizing radiation. Final report, January 1, 1990--December 31, 1992

    SciTech Connect

    Ayala, F.J.

    1992-12-31

    Results of an investigation of the gene coding for Cu, Zn superoxide dismutase (Sod) in Drosophila melanogaster seeking to understand the enzyme`s role in cell protection against ionizing radiation are reported. Components of the investigation include molecular characterization of the gene; measuring the response of different genotypes to increasing levels of radiation; and investigation of the processes that maintain the Sod polymorphism in populations. While two alleles, S and F, are commonly found at the Sod locus in natural populations of D. melanogaster we have isolated from a natural population a null (CA1) mutant that yields only 3.5% of normal SOD activity. The S, F, and CA1 alleles provide a model system to investigate SOD-dependent radioresistance, because each allele yields different levels of SOD, so that S > F >> CAl. The radioprotective effects of SOD can be established by showing protective effects for the various genotypes that correspond to those inequalities. Because the allele variants studied are derived from natural populations, the proposed investigation avoids problems that arise when mutants obtained my mutagenesis are used. Moreover, each allele is studied in multiple genetic backgrounds, so that we correct for effects attributable to other loci by randomizing these effects.

  11. Ionizing radiation and orthopaedic prostheses

    NASA Astrophysics Data System (ADS)

    Rimnac, Clare M.; Kurtz, Steven M.

    2005-07-01

    Ultra high molecular weight polyethylene (UHMWPE) materials have been used successfully as one half of the bearing couple (against metallic alloys or ceramics) in total hip and total knee joint replacements for four decades. This review describes the impact of ionizing radiation (used for sterilization and for microstructural modification via crosslinking) on the performance of UHMWPE total joint replacement components. Gamma radiation sterilization in air leads to oxidative degradation of UHMWPE joint components that occurs during shelf-aging and also during in vivo use. Efforts to mitigate oxidative degradation of UHMWPE joint components include gamma radiation sterilization in inert barrier-packaging and processing treatments to reduce free radicals. Ionizing radiation (both gamma and electron-beam) has recently been used to form highly crosslinked UHMWPEs that have better adhesive and abrasive wear resistance than non-crosslinked UHMWPE, thereby potentially improving the long-term performance of total joint replacements. Along with increased wear resistance, however, there are deleterious changes to ductility and fracture resistance of UHMWPE, and an increased risk of fracture of these components remains a clinical concern.

  12. Biochemical characterization of RecA variants that contribute to extreme resistance to ionizing radiation

    PubMed Central

    Piechura, Joseph R.; Tseng, Tzu-Ling; Hsu, Hsin-Fang; Byrne, Rose T.; Windgassen, Tricia A.; Chitteni-Pattu, Sindhu; Battista, John R.; Li, Hung-Wen; Cox, Michael M.

    2015-01-01

    Among strains of Escherichia coli that have evolved to survive extreme exposure to ionizing radiation, mutations in the recA gene are prominent and contribute substantially to the acquired phenotype. Changes at amino acid residue 276, D276A and D276N, occur repeatedly and in separate evolved populations. RecA D276A and RecA D276N exhibit unique adaptations to an environment that can require the repair of hundreds of double strand breaks. These two RecA protein variants (a) exhibit a faster rate of filament nucleation on DNA, as well as a slower extension under at least some conditions, leading potentially to a distribution of the protein among a higher number of shorter filaments, (b) promote DNA strand exchange more efficiently in the context of a shorter filament, and (c) are markedly less inhibited by ADP. These adaptations potentially allow RecA protein to address larger numbers of double strand DNA breaks in an environment where ADP concentrations are higher due to a compromised cellular metabolism. PMID:25559557

  13. Ionizing radiation detector

    DOEpatents

    Thacker, Louis H.

    1990-01-01

    An ionizing radiation detector is provided which is based on the principle of analog electronic integration of radiation sensor currents in the sub-pico to nano ampere range between fixed voltage switching thresholds with automatic voltage reversal each time the appropriate threshold is reached. The thresholds are provided by a first NAND gate Schmitt trigger which is coupled with a second NAND gate Schmitt trigger operating in an alternate switching state from the first gate to turn either a visible or audible indicating device on and off in response to the gate switching rate which is indicative of the level of radiation being sensed. The detector can be configured as a small, personal radiation dosimeter which is simple to operate and responsive over a dynamic range of at least 0.01 to 1000 R/hr.

  14. Ionizing-radiation resistance in the desiccation-tolerant cyanobacterium Chroococcidiopsis

    NASA Technical Reports Server (NTRS)

    Billi, D.; Friedmann, E. I.; Hofer, K. G.; Caiola, M. G.; Ocampo-Friedmann, R.

    2000-01-01

    The effect of X-ray irradiation on cell survival, induction, and repair of DNA damage was studied by using 10 Chroococcidiopsis strains isolated from desert and hypersaline environments. After exposure to 2.5 kGy, the percentages of survival for the strains ranged from 80 to 35%. In the four most resistant strains, the levels of survival were reduced by 1 or 2 orders of magnitude after irradiation with 5 kGy; viable cells were recovered after exposure to 15 kGy but not after exposure to 20 kGy. The severe DNA damage evident after exposure to 2.5 kGy was repaired within 3 h, and the severe DNA damage evident after exposure to 5 kGy was repaired within 24 h. The increase in trichloroacetic acid-precipitable radioactivity in the culture supernatant after irradiation with 2.5 kGy might have been due to cell lysis and/or an excision process involved in DNA repair. The radiation resistance of Chroococcidiopsis strains may reflect the ability of these cyanobacteria to survive prolonged desiccation through efficient repair of the DNA damage that accumulates during dehydration.

  15. Inhibition of Transforming Growth Factor-{beta} Signaling in Normal Lung Epithelial Cells Confers Resistance to Ionizing Radiation

    SciTech Connect

    Reeves, Anna; Zagurovskaya, Marianna; Gupta, Seema; Shareef, Mohammed M.; Mohiuddin, Mohammed; Ahmed, Mansoor M. . E-mail: mmahmed@geisinger.edu

    2007-05-01

    Purpose: To address the functional role of radiation-induced transforming growth factor-{beta} (TGF-{beta}) signaling in a normal epithelial background, we selected a spontaneously immortalized lung epithelial cell line derived from the normal lung tissue of a dominant-negative mutant of the TGF-{beta} RII ({delta}RII) transgenic mouse that conditionally expressed {delta}RII under the control of the metallothionein promoter (MT-1), and assessed this cell line's response to radiation. Methods and Materials: A spontaneously immortalized lung epithelial cell culture (SILECC) was established and all analyses were performed within 50 passages. Colony-forming and terminal transferase dUPT nick end labeling (TUNEL) assays were used to assess clonogenic inhibition and apoptosis, respectively. Western-blot analysis was performed to assess the kinetics of p21, bax, and RII proteins. Transforming growth factor-{beta}-responsive promoter activity was measured using dual-luciferase reporter assay. Results: Exposure to ZnSO{sub 4} inhibited TGF-{beta} signaling induced either by recombinant TGF-{beta}1 or ionizing radiation. The SILECC, treated with either ZnSO{sub 4} or neutralizing antibody against TGF-{beta}, showed a significant increase in radio-resistance compared to untreated cells. Furthermore, the expression of {delta}RII inhibited the radiation-induced up-regulation of the TGF-{beta} effector gene p21{sup waf1/cip1}. Conclusions: Our findings imply that inhibition of radiation-induced TGF-{beta} signaling via abrogation of the RII function enhances the radio-resistance of normal lung epithelial cells, and this can be directly attributed to the loss of TGF-{beta} signaling function.

  16. Reinforced polyquinoxaline gasket and method of preparing the same. [resistant to ionizing radiation and liquid hydrogen temperatures

    NASA Technical Reports Server (NTRS)

    Vanauken, R. (Inventor)

    1974-01-01

    A gasket or seal resistant to ionizing radiation and liquid hydrogen temperatures is made up of a laminated polyquinoxaline resin-fiberglass cloth body portion and a molded polyquinoxaline encapsulating film. The laminated body is prepared by stacking thin sheets of the resin alternately with fiberglass cloth and heating the assembly under pressure with the temperature, pressure and resin film thickness being controlled so that only partial impregnation of the fiberglass cloth is produced. The encapsulating resin film is preheated at about 300 f and applied to the laminate body by molding at a temperature of about 625 F. The molded gasket is then deflashed and post-cured by heating at 675 to 700 F.

  17. Deinococcus phoenicis sp. nov., an extreme ionizing-radiation-resistant bacterium isolated from the Phoenix Lander assembly facility.

    PubMed

    Vaishampayan, Parag; Roberts, Anne Hayden; Augustus, Angela; Pukall, Rüdiger; Schumann, Peter; Schwendner, Petra; Mayilraj, Shanmugam; Salmassi, Tina; Venkateswaran, Kasthuri

    2014-10-01

    A bacterial strain, designated 1P10ME(T), which was resistant to extreme doses of ionizing radiation, pale-pink, non-motile, and a tetrad-forming coccoid was isolated from a cleanroom at the Kennedy Space Center, where the Phoenix spacecraft was assembled. Strain 1P10ME(T) showed optimum growth at 30 °C, with a pH range for growth of 6.5-9.0 and was highly sensitive to sodium chloride, growing only in medium with no added NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 1P10ME(T) represents a novel member of the genus Deinococcus, with low sequence similarities (<93.5%) to recognized species of the genus Deinococcus. The predominant cellular fatty acid was C15:1ω6c. This novel strain exhibits extreme resistance to gamma radiation (D10 >8 kGy) and UV (D10 >1000 Jm(-2)). The results of our polyphasic taxonomic analyses suggest that strain 1P10ME(T) represents a novel species of the genus Deinococcus, for which the name Deinococcus phoenicis sp. nov. is proposed. The type strain is 1P10ME(T) ( = NRRL B-59546(T) = DSM 27173(T)). PMID:25030518

  18. Ionizing radiation promotes protozoan reproduction

    SciTech Connect

    Luckey, T.D.

    1986-11-01

    This experiment was performed to determine whether ionizing radiation is essential for maximum growth rate in a ciliated protozoan. When extraneous ionizing radiation was reduced to 0.15 mrad/day, the reproduction rate of Tetrahymena pyriformis was significantly less (P less than 0.01) than it was at near ambient levels, 0.5 or 1.8 mrad/day. Significantly higher growth rates (P less than 0.01) were obtained when chronic radiation was increased. The data suggest that ionizing radiation is essential for optimum reproduction rate in this organism.

  19. Resistance of holograms made in Polaroid DMP128 photopolymer to ionizing radiation damage

    SciTech Connect

    Golden, J.P.; Summers, G.P.; Carter, W.H.

    1988-11-01

    Because of their light weight and general wave-front-transforming ability, holograms appear potentially useful as beam correctors and collimators for diode-laser arrays in intersatellite optical data links. However, to survive in space a hologram must withstand damage from electrons and protons trapped in the Van Allen belts. We have found that holograms made with Polaroid DMP128 photopolymer on Suprasil-2 can withstand 63-MeV protons up to a total dose of 2 Mrad in (Si) and withstand /sup 60/Co gamma rays up to a total dose of 2 Mrad in (Si) without loss of diffraction efficiency. It appears that these holograms are sufficiently radiation hard for space application.

  20. [Modification of the body's resistance to acute ionizing radiation by synthetic beta-carotene].

    PubMed

    Beliaev, I K; Zaraĭskiĭ, A V; Limberg, V K; Vakulova, L A

    1992-01-01

    Radiomodifying efficiency of short-term and chronic medicinal and treatment-prophylactic enrichment of rations with artificial beta-carotene, administered at single doses of 0.1-10.0 mg, were studied after acute external gamma-irradiation of adult nonlinear and Wistar rats (0.029 Gy/s) or female SBA mice (0.0037 Gy/s), where the absorbed dose was equal to 8-3 Gy or 9.9-9.5 Gy, respectively. Suspension of beta-carotene paste in olive oil accelerated death of rats irradiated at doses of 8 and 7 Gy (P = 0.04), and shortened their lifespan. At a dose of 6 Gy single and long-term enrichment of rations with beta-carotene decreased the rate of rat death within 30 days from 33.3% to 16.7% (P = 0.14) and 3.3% (P = 0.01), while their life time was increased from 48 days to 67 days (P = 0.05) and 508 days (P = 0.01). beta-Carotene was found to affect favourably the radiation-induced (5 Gy) leukocytopenia, and decreased thymus mass (6 Gy) and body weight (8 Gy). In treatment-prophylactic enrichment with beta-carotene of mice (9.9 Gy) ration their survival was increased from 15% to 30% and lifespan from 14.4 days to 28.9 days (P = 0.05). During medicinal or treatment-prophylactic courses of beta-carotene death of mice (9.7 Gy) was decreased from 75% to 35% (P = 0.01) or 60% and life time was increased from 16.7 days to 22.17 days or 39.9 days (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1298128

  1. Total Ionizing Dose (TID) Effects of γ Ray Radiation on Ag/AlOx/Pt Resistive Switching Memory

    NASA Astrophysics Data System (ADS)

    Yuan, Fang; Zhang, Zhigang; Shen, Shanshan; Pan, Liyang; Xu, Jun; Memory Research Team

    2014-03-01

    The TID effects of γ rays generated from a 60Co source on the Ag/AlOx/Pt resistive switching (RS) memory is studied. Memory performances, including initial resistance state (IRS), low/high resistance state (LRS/HRS), forming voltage (Vf) , switching voltage (Vset/Vreset) and retention reliability are examined on the memory devices before and after exposure to 1M rad (Si) radiation. The LRS is robust to the radiation whereas a little degeneration of uniformity is found in IRS and HRS, which is caused by the radiation induced defects (mainly holes), trapped in the oxide. For the same reason, Vf increases several multiples after radiation. However surprisingly, both Vset and Vreset decrease during the RS and the retention performance is greatly improved. Based on these TID effects, it is proposed that the RS mechanism in Ag/AlOx/Pt, Ag conducting filament based switching, may be reinforced through γ radiation, which assists in stabilizing the growth/rupture of Ag filaments. The high radiation tolerance of AlOx-based RS memory devices suggests a potential for aerospace and nuclear applications. Supported by the National Natural Science Foundation of China (20111300789).

  2. Chemical protection against ionizing radiation

    NASA Astrophysics Data System (ADS)

    Maisin, J. R.

    Some of the problems related to chemical protection against ionizing radiation are discussed with emphasis on : definition, classification, degree of protection, mechanisms of action and toxicity. Results on the biological response modifyers (BRMs) and on the combination of nontoxic (i.e. low) doses of sulphydryl radioprotectors and BRMs are presented.

  3. Ionizing Radiation and Its Risks

    PubMed Central

    Goldman, Marvin

    1982-01-01

    Penetrating ionizing radiation fairly uniformly puts all exposed molecules and cells at approximately equal risk for deleterious consequences. Thus, the original deposition of radiation energy (that is, the dose) is unaltered by metabolic characteristics of cells and tissue, unlike the situation for chemical agents. Intensely ionizing radiations, such as neutrons and alpha particles, are up to ten times more damaging than sparsely ionizing sources such as x-rays or gamma rays for equivalent doses. Furthermore, repair in cells and tissues can ameliorate the consequences of radiation doses delivered at lower rates by up to a factor of ten compared with comparable doses acutely delivered, especially for somatic (carcinogenic) and genetic effects from x- and gamma-irradiation exposure. Studies on irradiated laboratory animals or on people following occupational, medical or accidental exposures point to an average lifetime fatal cancer risk of about 1 × 10-4 per rem of dose (100 per 106 person-rem). Leukemia and lung, breast and thyroid cancer seem more likely than other types of cancer to be produced by radiation. Radiation exposures from natural sources (cosmic rays and terrestrial radioactivity) of about 0.1 rem per year yield a lifetime cancer risk about 0.1 percent of the normally occurring 20 percent risk of cancer death. An increase of about 1 percent per rem in fatal cancer risk, or 200 rem to double the “background” risk rate, is compared with an estimate of about 100 rem to double the genetic risk. Newer data suggest that the risks for low-level radiation are lower than risks estimated from data from high exposures and that the present 5 rem per year limit for workers is adequate. PMID:6761969

  4. 29 CFR 1926.53 - Ionizing radiation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Protection Against Radiation (10 CFR part 20), relating to protection against occupational radiation exposure... 29 Labor 8 2011-07-01 2011-07-01 false Ionizing radiation. 1926.53 Section 1926.53 Labor... § 1926.53 Ionizing radiation. (a) In construction and related activities involving the use of sources...

  5. 29 CFR 1926.53 - Ionizing radiation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Protection Against Radiation (10 CFR part 20), relating to protection against occupational radiation exposure... 29 Labor 8 2012-07-01 2012-07-01 false Ionizing radiation. 1926.53 Section 1926.53 Labor... § 1926.53 Ionizing radiation. (a) In construction and related activities involving the use of sources...

  6. Radiation-resistant microorganism

    DOEpatents

    Fliermans, Carl B.

    2007-01-09

    An isolated and purified bacterium is provided which was isolated from a high-level radioactive waste site of mixed waste. The isolate has the ability to degrade a wide variety of organic contaminants while demonstrating high tolerance to ionizing radiation. The organism is uniquely suited to bioremediation of a variety or organic contaminants while in the presence of ionizing radiation.

  7. Radiation-resistant microorganism

    DOEpatents

    Fliermans, Carl B.

    2010-06-15

    An isolated and purified bacterium is provided which was isolated from a high-level radioactive waste site of mixed waste. The isolate has the ability to degrade a wide variety of organic contaminants while demonstrating high tolerance to ionizing radiation. The organism is uniquely suited to bioremediation of a variety or organic contaminants while in the presence of ionizing radiation.

  8. Device for detecting ionizing radiation

    SciTech Connect

    Anatychuk, L.I.; Kharitonov, J.P.; Kusniruk, V.F.; Meir, V.A.; Melnik, A.P.; Ponomarev, V.S.; Skakodub, V.A.; Sokolov, A.D.; Subbotin, V.G.; Zhukovsky, A.N.

    1980-10-28

    The present invention relates to ionizing radiation sensors, and , more particularly, to semiconductor spectrometers with thermoelectric cooling, and can most advantageously be used in mineral raw material exploration and evaluation under field conditions. The spectrometer comprises a vacuum chamber with an entrance window for passing the radiation therethrough. The vacuum chamber accommodates a thermoelectric cooler formed by a set of peltier elements. A heat conducting plate is mounted on the cold side of the thermoelectric cooler, and its hot side is provided with a radiator. Mounted on the heat conducting plate are sets of peltier elements, integral with the thermoelectric cooler and independent of one another. The peltier elements of these sets are stacked so as to develop the minimum temperature conditions on one set carrying a semiconductor detector and to provide the maximum refrigeration capacity conditions on the other set provided with the field-effect transistor mounted thereon.

  9. Complete genome sequence of Hymenobacter sp. strain PAMC26554, an ionizing radiation-resistant bacterium isolated from an Antarctic lichen.

    PubMed

    Oh, Tae-Jin; Han, So-Ra; Ahn, Do-Hwan; Park, Hyun; Kim, Augustine Yonghwi

    2016-06-10

    A Gram-negative, rod-shaped, red-pink in color, and UV radiation-resistant bacterium Hymenobacter sp. strain PAMC26554 was isolated from Usnea sp., an Antarctic lichen, and belongs to the class of Cytophagia and the phylum of Bacteroidetes. The complete genome of Hymenobacter sp. PAMC26554 consists of one chromosome (5,244,843bp) with two plasmids (199,990bp and 6421bp). The genomic sequence indicates that Hymenobacter sp. strain PAMC26554 possesses several genes involved in the nucleotide excision repair pathway that protects damaged DNA. This complete genome information will help us to understand its adaptation and novel survival strategy in the Antarctic extreme cold environment. PMID:27063139

  10. Enhanced radiation resistant fiber optics

    DOEpatents

    Lyons, P.B.; Looney, L.D.

    1993-11-30

    A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures.

  11. 29 CFR 1910.1096 - Ionizing radiation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 6 2014-07-01 2013-07-01 true Ionizing radiation. 1910.1096 Section 1910.1096 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS (CONTINUED) Toxic and Hazardous Substances § 1910.1096 Ionizing radiation. (a)...

  12. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, Minoru; Watson, E. Bruce; Acocella, John

    1986-01-01

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

  13. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, M.; Watson, E.B.; Acocella, J.

    1986-11-04

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

  14. Ionizing radiation enhances therapeutic activity of mda-7/IL-24: overcoming radiation- and mda-7/IL-24-resistance in prostate cancer cells overexpressing the antiapoptotic proteins bcl-xL or bcl-2.

    PubMed

    Su, Z-Z; Lebedeva, I V; Sarkar, D; Emdad, L; Gupta, P; Kitada, S; Dent, P; Reed, J C; Fisher, P B

    2006-04-13

    Subtraction hybridization applied to terminally differentiating human melanoma cells identified mda-7/IL-24, a cytokine belonging to the IL-10 gene superfamily. Adenoviral-mediated delivery of mda-7/IL-24 (Ad.mda-7) provokes apoptosis selectively in a wide spectrum of cancers in vitro in cell culture, in vivo in human tumor xenograft animal models and in patients with advanced carcinomas and melanomas. In human prostate cancer cells, a role for mitochondrial dysfunction and induction of reactive oxygen species in the apoptotic process has been established. Ectopic overexpression of bcl-xL and bcl-2 prevents these changes including apoptosis induction in prostate tumor cells by Ad.mda-7. We now document that this resistance to apoptosis can be reversed by treating bcl-2 family overexpressing prostate tumor cells with ionizing radiation in combination with Ad.mda-7 or purified GST-MDA-7 protein. Additionally, radiation augments apoptosis induction by mda-7/IL-24 in parental and neomycin-resistant prostate tumor cells. Radiosensitization to mda-7/IL-24 is dependent on JNK signaling, as treatment with the JNK 1/2/3 inhibitor SP600125 abolishes this effect. Considering that elevated expression of bcl-xL and bcl-2 are frequent events in prostate cancer development and progression, the present studies support the use of ionizing radiation in combination with mda-7/IL-24 as a means of augmenting the therapeutic benefit of this gene in prostate cancer, particularly in the context of tumors displaying resistance to radiation therapy owing to bcl-2 family member overexpression. PMID:16331261

  15. Accreditation of ionizing radiation protection programs

    SciTech Connect

    McDonald, J.C.; Swinth, K.L.; Selby, J.M.

    1991-10-01

    There are over one million workers in the United States who have the potential to be exposed to ionizing radiation. Therefore, it is necessary to determine accurately the quantity of radiation to which they may have been exposed. This quantity if measured by personnel dosimeters that are carried by individuals requiring radiation monitoring. Accreditation of the organizations which evaluate this quantity provides official recognition of the competence of these organizations. Accreditation programs in the field of ionizing radiation protection have been in operation for a number of years, and their experience has demonstrated that such programs can help to improve performance.

  16. Hazards to space workers from ionizing radiation

    NASA Technical Reports Server (NTRS)

    Lyman, J. T.

    1980-01-01

    A compilation of background information and a preliminary assessment of the potential risks to workers from the ionizing radiation encountered in space is provided. The report: (1) summarizes the current knowledge of the space radiation environment to which space workers will be exposed; (2) reviews the biological effects of ionizing radiation considered of major importance to a SPS project; and (3) discusses the health implications of exposure of populations of space workers to the radiations likely to penetrate through the shielding provided by the SPS work stations and habitat shelters of the SPS Reference System.

  17. Potential mechanisms involved in resistant phenotype of MCF-7 breast carcinoma cells to ionizing radiation induced apoptosis

    NASA Astrophysics Data System (ADS)

    Wang, Yan-ling; Zhang, Hong; Li, Ning; Wang, Xiao-hu; Hao, Ji-fang; Zhao, Wei-ping

    2009-03-01

    In the present study, we investigated the mechanisms of apoptosis resistance and the roles of the phosphorylation of BRCA1, p21, the Bax/Bcl-2 protein ratio and cell cycle arrest in IR-induced apoptosis in MCF-7 cells. X-irradiation, in particular at low dose (1 Gy), but not carbon ion irradiation, had a significant antiproliferative effect on the growth of MCF-7 cells. 1 Gy X-irradiation resulted in G1 and G2 phase arrest, but 4 Gy induced a significant G1 block. In contrast, carbon ion irradiation resulted in a significant accumulation in the G2 phase. Concomitant with the phosphorylation of H2AX induced by DNA damage, carbon ion irradiation resulted in an approximately 1.9-2.8-fold increase in the phosphorylation of BRCA1 on serine residue 1524, significantly greater than that detected for X-irradiation. Carbon ion irradiation caused a dramatic increase in p21 expression and drastic decrease in Bax expression compared with X-irradiation. The data implicated that phosphorylation of BRCA1 on serine residue 1524 might, at least partially, induce p21 expression but repress Bax expression. Together, our results suggested that the phosphorylation of BRCA1 at Ser-1524 might contribute to the G2 phase arrest and might be an upstream signal involved in preventing apoptosis signal via upregulation of p21 and downregulation of the Bax/Bcl-2 ratio.

  18. 2.2.1 Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Kasch, K.-U.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.2.1 Ionizing Radiation' of the Section '2.2 Kinds of Radiation' of the Chapter '2 Radiation and Biological Effects' with the contents:

  19. Spatio-temporal changes in glutathione and thioredoxin redox couples during ionizing radiation-induced oxidative stress regulate tumor radio-resistance.

    PubMed

    Patwardhan, R S; Sharma, D; Checker, R; Thoh, M; Sandur, S K

    2015-10-01

    Ionizing radiation (IR)-induced oxidative stress in tumor cells is effectively managed by constitutive and inducible antioxidant defense systems. This study was initiated to understand the relative contribution of different redox regulatory systems in determining the tumor radio-resistance. In this study, human T-cell lymphoma (Jurkat) cells were exposed to IR (4 Gy) and monitored for the spatio-temporal changes in cellular redox regulatory parameters. We monitored the changes in the levels of reactive oxygen species (ROS) (total, mitochondrial, primary, and secondary), thiols (total, surface, and intracellular), GSH/GSSG ratio, antioxidant enzyme activity viz. thioredoxin (Trx), Trx reductase (TrxR), glutathione peroxidase, and glutathione reductase with respect to time. We have also measured protein glutathionylation. We observed that tumor cells mount a biphasic response after IR exposure which can be divided into early (0-6 h) and late (16-48 h) responses in terms of changes in cellular redox parameters. During early response, constitutively active GSH and Trx systems respond to restore cellular redox balance to pre-exposure levels and help in activation of redox-sensitive transcription factor Nrf-2. During late response, increase in the levels of antioxidants GSH and Trx rescue cells against IR-mediated damage. We observed that disruption of either glutathione or thioredoxin metabolism led to partial impairment of ability of cells to survive against IR-induced damage. But simultaneous disruption of both the pathways significantly increased radio sensitivity of Jurkat cells. This highlighted the importance of these two antioxidant pathways in regulating redox homeostasis under conditions of IR-induced oxidative stress. PMID:26021764

  20. Ionizing radiation bioeffects and risks

    SciTech Connect

    1992-12-31

    Radiation protection requires an understanding of the prompt and long-term biological effects of radiation and numerical estimates of radiation risks. This chapter presents the characteristics of the ``acute radiation syndrome`` which can occur if an individual is exposed to high doses of radiation, and the effects of high levels of radiation on the skin. It also describes the long term bioeffects of low levels of low LET radiation on individuals and the whole population. These risks are quantified and are put in perspective by comparison to other societal hazards.

  1. The cell cycle inhibitor Cdkn1a regulates Langerhans cell radiation resistance and promotes T regulatory cell generation upon exposure to ionizing irradiation

    PubMed Central

    Price, Jeremy G.; Idoyaga, Juliana; Salmon, Hélène; Hogstad, Brandon; Bigarella, Carolina L.; Ghaffari, Saghi; Leboeuf, Marylene; Merad, Miriam

    2015-01-01

    Treatment with ionizing irradiation (IR) may lead to accumulation of tumor-infiltrating T regulatory (Treg) cells and subsequent tumor resistance to radiotherapy. Here we focused on the contribution of the epidermal mononuclear phagocytes, Langerhans cells (LCs), to this phenomenon because of their ability to resist depletion by high-dose IR. We found that LCs resisted apoptosis and rapidly repaired DNA damage post-IR. Particularly, we found that CDKN1A (cyclin-dependent kinase inhibitor 1A, also known as p21) was overexpressed in LCs, and that Cdkn1a−/− LCs underwent apoptosis and accumulated DNA damage following IR treatment. Wild-type, but not Cdkn1a−/−, LCs up-regulated major histocompatibility complex class II molecules, migrated to the draining lymph nodes and increased Treg cell numbers upon exposure to IR. These findings suggest a means for manipulating LC IR-resistance to increase cutaneous tumor response to radiotherapy. PMID:26343536

  2. Chemical protection against ionizing radiation. Final report

    SciTech Connect

    Livesey, J.C.; Reed, D.J.; Adamson, L.F.

    1984-08-01

    The scientific literature on radiation-protective drugs is reviewed. Emphasis is placed on the mechanisms involved in determining the sensitivity of biological material to ionizing radiation and mechanisms of chemical radioprotection. In Section I, the types of radiation are described and the effects of ionizing radiation on biological systems are reviewed. The effects of ionizing radiation are briefly contrasted with the effects of non-ionizing radiation. Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Inlcuded in the list of these factors are water, oxygen, thiols, vitamins and antioxidants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in determining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. 495 references.

  3. Dosimetry and Biological Effects of Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Kanyár, B.; Köteles, G. J.

    The extension of the use of ionizing radiation and the new biological information on the effects of radiation exposure that is now becoming available, present new challenges to the development of concepts and methodology in determination of doses and assessment of hazards for the protection of living systems. Concise information is given on the deterministic and stochastic effects, on the debate concerning the effects of low doses, the detection of injuries by biological assays, and the radiation sickness.

  4. Roles of the Major, Small, Acid-Soluble Spore Proteins and Spore-Specific and Universal DNA Repair Mechanisms in Resistance of Bacillus subtilis Spores to Ionizing Radiation from X Rays and High-Energy Charged-Particle Bombardment▿

    PubMed Central

    Moeller, Ralf; Setlow, Peter; Horneck, Gerda; Berger, Thomas; Reitz, Günther; Rettberg, Petra; Doherty, Aidan J.; Okayasu, Ryuichi; Nicholson, Wayne L.

    2008-01-01

    The role of DNA repair by nonhomologous end joining (NHEJ), homologous recombination, spore photoproduct lyase, and DNA polymerase I and genome protection via α/β-type small, acid-soluble spore proteins (SASP) in Bacillus subtilis spore resistance to accelerated heavy ions (high-energy charged [HZE] particles) and X rays has been studied. Spores deficient in NHEJ and α/β-type SASP were significantly more sensitive to HZE particle bombardment and X-ray irradiation than were the recA, polA, and splB mutant and wild-type spores, indicating that NHEJ provides an efficient DNA double-strand break repair pathway during spore germination and that the loss of the α/β-type SASP leads to a significant radiosensitivity to ionizing radiation, suggesting the essential function of these spore proteins as protectants of spore DNA against ionizing radiation. PMID:18055591

  5. Effects of ionizing radiation on modern ion exchange materials

    SciTech Connect

    Marsh, S.F.; Pillay, K.K.S.

    1993-10-01

    We review published studies of the effects of ionizing radiation on ion exchange materials, emphasizing those published in recent years. A brief overview is followed by a more detailed examination of recent developments. Our review includes styrene/divinylbenzene copolymers with cation-exchange or anion-exchange functional groups, polyvinylpyridine anion exchangers, chelating resins, multifunctional resins, and inorganic exchangers. In general, strong-acid cation exchange resins are more resistant to radiation than are strong-base anion exchange resins, and polyvinylpyridine resins are more resistant than polystyrene resins. Cross-linkage, salt form, moisture content, and the surrounding medium all affect the radiation stability of a specific exchanger. Inorganic exchangers usually, but not always, exhibit high radiation resistance. Liquid ion exchangers, which have been used so extensively in nuclear processing applications, also are included.

  6. Therapeutic Applications of Ionizing Radiations

    NASA Astrophysics Data System (ADS)

    Sánchez-Santos, María Elena

    The aim of radiation therapy is to deliver a precisely measured dose of radiation to a defined tumour volume with minimal damage to the surrounding healthy tissue, resulting in the eradication of the tumour, a higher quality of life with palliation of symptoms of the disease, and the prolongation of survival at competitive cost. Together with surgery and pharmacology, radiotherapy is presently one of the most important therapeutical weapons against cancer. This chapter provides an overview of the clinical use of radiation, with emphasis on the optimisation of treatment planning and delivery, and a top level summary of state-of-the-art techniques in radiation therapy.

  7. Diffuse ionizing radiation within HH jets

    SciTech Connect

    Esquivel, A.; Raga, A. C. E-mail: raga@nucleares.unam.mx

    2013-12-20

    We present numerical hydrodynamical simulations of a time-dependent ejection velocity precessing jet. The parameters used in our models correspond to a high excitation Herbig-Haro object, such as HH 80/81. We have included the transfer of ionizing radiation produced within the shocked regions of the jet. The radiative transfer is computed with a ray-tracing scheme from all the cells with an emissivity above a certain threshold. We show the development of a radiative precursor, and compare the morphology with a model without the diffuse radiation. Our simulations show that the morphology of the Hα emission is affected considerably if the diffuse ionizing radiation is accounted for. The predicted Hα position-velocity diagram (i.e., spatially resolved emission line profiles) from a model with the transfer of ionizing radiation has a relatively strong component at zero velocity, corresponding to the radiative precursor. Qualitatively similar 'zero velocity components' are observed in HH 80/81 and in the jet from Sanduleak's star in the Large Magellanic Cloud.

  8. (Oncogenic action of ionizing radiation)

    SciTech Connect

    Not Available

    1990-01-01

    An extensive experiment involving approximately 400 rats exposed to the neon ion beam at the Bevalac in Berkeley, CA and to electrons is nearing completion. The carcinogenicity of energetic electrons was determined for comparison with the neon ion results. As in past reports we will describe progress in three areas corresponding to the specific aims of the proposal: (1) carcinogenesis and DNA strand breaks in rat skin following exposure by the neon ions or electrons; (2) DNA strand breaks in the epidermis as a function of radiation penetration; (3) oncogene activation in radiation-induced rat skin cancers. 72 refs., 6 tabs.

  9. Roles of ionizing radiation in cell transformation

    SciTech Connect

    Tobias, C.A.; Albright, N.W.; Yang, T.C.

    1983-07-01

    Earlier the authors described a repair misrepair model (RMR-I) which is applicable for radiations of low LET, e.g., x rays and gamma rays. RMR-II was described later. Here is introduced a mathematical modification of the RMR model, RMR-III, which is intended to describe lethal effects caused by heavily ionizing tracks. 31 references, 4 figures.

  10. Composite scintillators for detection of ionizing radiation

    DOEpatents

    Dai, Sheng [Knoxville, TN; Stephan, Andrew Curtis [Knoxville, TN; Brown, Suree S [Knoxville, TN; Wallace, Steven A [Knoxville, TN; Rondinone, Adam J [Knoxville, TN

    2010-12-28

    Applicant's present invention is a composite scintillator having enhanced transparency for detecting ionizing radiation comprising a material having optical transparency wherein said material comprises nano-sized objects having a size in at least one dimension that is less than the wavelength of light emitted by the composite scintillator wherein the composite scintillator is designed to have selected properties suitable for a particular application.

  11. Ionizing radiation and cardiovascular disease.

    PubMed

    Hoel, David G

    2006-09-01

    For more than 15 years the A-bomb survivor studies have shown increased noncancer mortality due to radiation exposures. The most prominent cause of this increase is circulatory disease mortality. Although the estimated relative risk is less than for solid cancers (1.2 versus 1.6 per Sv), there are measurable increases in cardiovascular disease mortality at doses greater than 0.5 Sv. The evidence for circulatory diseases in mortality studies of occupational cohorts exposed to external radiation is less compelling. It is generally accepted that atherosclerosis is an inflammatory disease of the arteries and a risk factor for myocardial infarction. Immunological markers for inflammatory disease have been shown to be dose related in A-bomb survivors. Evidence from animal studies reveals increased cardiovascular mortality and arterial endothelial damage from both neutron and, to a lesser extent, gamma exposures. PMID:17119211

  12. Strong resistance of Arabidopsis thaliana and Raphanus sativus seeds for ionizing radiation as studied by ESR, ENDOR, ESE spectroscopy and germination measurement: Effect of long-lived and super-long-lived radicals

    NASA Astrophysics Data System (ADS)

    Kumagai, Jun; Katoh, Hiromi; Kumada, Takayuki; Tanaka, Atsushi; Tano, Shigemitsu; Miyazaki, Tetsuo

    2000-01-01

    Resistance of seeds for ionizing radiation effects on Arabidopsis thaliana and Raphanus sativus seeds were investigated by ESR, ENDOR, ESE spectroscopy and germination measurement. Two types of free radicals, such as long-lived (LL) and super-long-lived (SL) radicals, were produced by the γ-irradiation in the seeds. More than 90% of the 1 kGy-irradiated-seeds can germinate probably by decreasing the LL radicals by absorbing water. 10 kGy-irradiated-seeds cannot germinate at all probably due to the existence of significant amounts of the SL radicals even after absorbing water.

  13. New standards for ionizing radiation measurements

    SciTech Connect

    Lamperti, P.J.; Johnson, C.M.

    1995-12-31

    The Ionizing Radiation Division has developed new national standards for mammographic X rays and for brachytherapy sources, such as iodine-125. The Attix chamber, a variable volume free-air ionization chamber, has been established as the primary national standard for mammographic X rays. The Attix chamber resides in the newly developed NIST Mammography Calibration Range and will be used to perform routine calibrations. The wide-angle free-air ionization chamber utilizes a large volume and a novel electric field configuration in order to circumvent the limitations of conventional free-air chambers. Seventeen beam qualities for X rays from molybdenum (Mo) and rhodium (Rh) anodes have been parameterized for the calibration of mammographic ionization chambers. The beam qualities available include anode/filter combinations of Mo/Mo, Mo/Rh and Rh/Rh. The mammography range was developed in collaborations with the U.S. Food and Drug Administration`s (FDA) Center for Devices and Radiological Health, the implementors of the Mammography Quality Standards Act (MQSA) of 1992. The wide-angle free-air ionization chamber has been used to measure the output of two types of iodine-125 seeds, those with resin balls and those with silver wire. Both free-air chambers have been intercompared with the Ritz parallel-plate free-air ionization chamber.

  14. Proteomic Analysis of Trypanosoma cruzi Response to Ionizing Radiation Stress

    PubMed Central

    Vieira, Helaine Graziele Santos; Grynberg, Priscila; Bitar, Mainá; Pires, Simone da Fonseca; Hilário, Heron Oliveira; Macedo, Andrea Mara; Machado, Carlos Renato; de Andrade, Hélida Monteiro; Franco, Glória Regina

    2014-01-01

    Trypanosoma cruzi, the causative agent of Chagas disease, is extremely resistant to ionizing radiation, enduring up to 1.5 kGy of gamma rays. Ionizing radiation can damage the DNA molecule both directly, resulting in double-strand breaks, and indirectly, as a consequence of reactive oxygen species production. After a dose of 500 Gy of gamma rays, the parasite genome is fragmented, but the chromosomal bands are restored within 48 hours. Under such conditions, cell growth arrests for up to 120 hours and the parasites resume normal growth after this period. To better understand the parasite response to ionizing radiation, we analyzed the proteome of irradiated (4, 24, and 96 hours after irradiation) and non-irradiated T. cruzi using two-dimensional differential gel electrophoresis followed by mass spectrometry for protein identification. A total of 543 spots were found to be differentially expressed, from which 215 were identified. These identified protein spots represent different isoforms of only 53 proteins. We observed a tendency for overexpression of proteins with molecular weights below predicted, indicating that these may be processed, yielding shorter polypeptides. The presence of shorter protein isoforms after irradiation suggests the occurrence of post-translational modifications and/or processing in response to gamma radiation stress. Our results also indicate that active translation is essential for the recovery of parasites from ionizing radiation damage. This study therefore reveals the peculiar response of T. cruzi to ionizing radiation, raising questions about how this organism can change its protein expression to survive such a harmful stress. PMID:24842666

  15. Atmospheric Ionizing Radiation and Human Exposure

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Goldhagen, P.; Friedberg, W.; DeAngelis, G.; Clem, J. M.; Copeland, K.; Bidasaria, H. B.

    2004-01-01

    Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the lower atmosphere near the Earth s surface tend to be dominated by the terrestrial radioisotopes especially along the coastal plain and interior low lands and have only minor contributions from neutrons (11 percent). The world average is substantially larger but the high altitude cities especially have substantial contributions from neutrons (25 to 45 percent). Understanding the world distribution of neutron exposures requires an improved understanding of the latitudinal, longitudinal, altitude and spectral distribution that depends on local terrain and time. These issues are being investigated in a combined experimental and theoretical program. This paper will give an overview of human exposures and describe the development of improved environmental models.

  16. Atmospheric Ionizing Radiation and Human Exposure

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Mertens, Christopher J.; Goldhagen, Paul; Friedberg, W.; DeAngelis, G.; Clem, J. M.; Copeland, K.; Bidasaria, H. B.

    2005-01-01

    Atmospheric ionizing radiation is of interest, apart from its main concern of aircraft exposures, because it is a principal source of human exposure to radiations with high linear energy transfer (LET). The ionizing radiations of the lower atmosphere near the Earth s surface tend to be dominated by the terrestrial radioisotopes. especially along the coastal plain and interior low lands, and have only minor contributions from neutrons (11 percent). The world average is substantially larger but the high altitude cities especially have substantial contributions from neutrons (25 to 45 percent). Understanding the world distribution of neutron exposures requires an improved understanding of the latitudinal, longitudinal, altitude and spectral distribution that depends on local terrain and time. These issues are being investigated in a combined experimental and theoretical program. This paper will give an overview of human exposures and describe the development of improved environmental models.

  17. Cataracts induced by microwave and ionizing radiation

    SciTech Connect

    Lipman, R.M.; Tripathi, B.J.; Tripathi, R.C.

    1988-11-01

    Microwaves most commonly cause anterior and/or posterior subcapsular lenticular opacities in experimental animals and, as shown in epidemiologic studies and case reports, in human subjects. The formation of cataracts seems to be related directly to the power of the microwave and the duration of exposure. The mechanism of cataractogenesis includes deformation of heat-labile enzymes, such as glutathione peroxide, that ordinarily protect lens cell proteins and membrane lipids from oxidative damage. Oxidation of protein sulfhydryl groups and the formation of high-molecular-weight aggregates cause local variations in the orderly structure of the lens cells. An alternative mechanism is thermoelastic expansion through which pressure waves in the aqueous humor cause direct physical damage to the lens cells. Cataracts induced by ionizing radiation (e.g., X-rays and gamma rays) usually are observed in the posterior region of the lens, often in the form of a posterior subcapsular cataract. Increasing the dose of ionizing radiation causes increasing opacification of the lens, which appears after a decreasing latency period. Like cataract formation by microwaves, cataractogenesis induced by ionizing radiation is associated with damage to the lens cell membrane. Another possible mechanism is damage to lens cell DNA, with decreases in the production of protective enzymes and in sulfur-sulfur bond formation, and with altered protein concentrations. Until further definitive conclusions about the mechanisms of microwaves and ionizing radiation induced cataracts are reached, and alternative protective measures are found, one can only recommend mechanical shielding from these radiations to minimize the possibility of development of radiation-induced cataracts. 74 references.

  18. Ionizing radiation exposure of LDEF

    NASA Technical Reports Server (NTRS)

    Benton, E. V. (Editor); Heinrich, W. (Editor)

    1990-01-01

    The Long Duration Exposure Facility (LDEF) was launched into orbit by the Space Shuttle 'Challenger' mission 41C on 6 April 1984 and was deployed on 8 April 1984. The original altitude of the circular orbit was 258.5 nautical miles (479 km) with the orbital inclination being 28.5 degrees. The 21,500 lb NASA Langley Research Center satellite, having dimensions of some 30x14 ft was one of the largest payloads ever deployed by the Space Shuttle. LDEF carried 57 major experiments and remained in orbit five years and nine months (completing 32,422 orbits). It was retrieved by the Shuttle 'Columbia' on January 11, 1990. By that time, the LDEF orbit had decayed to the altitude of 175 nm (324 km). The experiments were mounted around the periphery of the LDEF on 86 trays and involved the representation of more than 200 investigators, 33 private companies, 21 universities, seven NASA centers, nine Department of Defense laboratories and eight foreign countries. The experiments covered a wide range of disciplines including basic science, electronics, optics, materials, structures, power and propulsion. The data contained in the LDEF mission represents an invaluable asset and one which is not likely to be duplicated in the foreseeable future. The data and the subsequent knowledge which will evolve from the analysis of the LDEF experiments will have a very important bearing on the design and construction of the Space Station Freedom and indeed on other long-term, near-earth orbital space missions. A list of the LDEF experiments according to experiment category and sponsor is given, as well as a list of experiments containing radiation detectors on LDEF including the LDEF experiment number, the title of the experiment, the principal investigator, and the type of radiation detectors carried by the specific experiment.

  19. Are Organisms Adapting to Ionizing Radiation at Chernobyl?

    PubMed

    Møller, Anders Pape; Mousseau, Timothy Alexander

    2016-04-01

    Numerous organisms have shown an ability to survive and reproduce under low-dose ionizing radiation arising from natural background radiation or from nuclear accidents. In a literature review, we found a total of 17 supposed cases of adaptation, mostly based on common garden experiments with organisms only deriving from typically two or three sampling locations. We only found one experimental study showing evidence of improved resistance to radiation. Finally, we examined studies for the presence of hormesis (i.e., superior fitness at low levels of radiation compared with controls and high levels of radiation), but found no evidence to support its existence. We conclude that rigorous experiments based on extensive sampling from multiple sites are required. PMID:26868287

  20. Total ionizing dose effect of γ-ray radiation on the switching characteristics and filament stability of HfOx resistive random access memory

    SciTech Connect

    Fang, Runchen; Yu, Shimeng; Gonzalez Velo, Yago; Chen, Wenhao; Holbert, Keith E.; Kozicki, Michael N.; Barnaby, Hugh

    2014-05-05

    The total ionizing dose (TID) effect of gamma-ray (γ-ray) irradiation on HfOx based resistive random access memory was investigated by electrical and material characterizations. The memory states can sustain TID level ∼5.2 Mrad (HfO{sub 2}) without significant change in the functionality or the switching characteristics under pulse cycling. However, the stability of the filament is weakened after irradiation as memory states are more vulnerable to flipping under the electrical stress. X-ray photoelectron spectroscopy was performed to ascertain the physical mechanism of the stability degradation, which is attributed to the Hf-O bond breaking by the high-energy γ-ray exposure.

  1. Overview of Atmospheric Ionizing Radiation (AIR)

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Maiden, D. L.; Goldhagen, P.; Tai, H.; Shinn, J. L.

    2003-01-01

    The SuperSonic Transport (SST) development program within the US was based at the Langley Research Center as was the Apollo radiation testing facility (Space Radiation Effects Laboratory) with associated radiation research groups. It was natural for the issues of the SST to be first recognized by this unique combination of research programs. With a re-examination of the technologies for commercial supersonic flight and the possible development of a High Speed Civil Transport (HSCT), the remaining issues of the SST required resolution. It was the progress of SST radiation exposure research program founded by T. Foelsche at the Langley Research Center and the identified remaining issues after that project over twenty-five years ago which became the launch point of the current atmospheric ionizing radiation (AIR) research project. Added emphasis to the need for reassessment of atmospheric radiation resulted from the major lowering of the recommended occupational exposure limits, the inclusion of aircrew as radiation workers, and the recognition of civil aircrew as a major source of occupational exposures. Furthermore, the work of Ferenc Hajnal of the Environmental Measurements Laboratory brought greater focus to the uncertainties in the neutron flux at high altitudes. A re-examination of the issues involved was committed at the Langley Research Center and by the National Council on Radiation Protection (NCRP). As a result of the NCRP review, a new flight package was assembled and flown during solar minimum at which time the galactic cosmic radiation is at a maximum (June 1997). The present workshop is the initial analysis of the new data from that flight. The present paper is an overview of the status of knowledge of atmospheric ionizing radiations. We will re-examine the exposures of the world population and examine the context of aircrew exposures with implications for the results of the present research. A condensed version of this report was given at the 1998

  2. Alloy nanoparticle synthesis using ionizing radiation

    DOEpatents

    Nenoff, Tina M.; Powers, Dana A.; Zhang, Zhenyuan

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  3. Waveshifters and Scintillators for Ionizing Radiation Detection

    SciTech Connect

    B.Baumgaugh; J.Bishop; D.Karmgard; J.Marchant; M.McKenna; R.Ruchti; M.Vigneault; L.Hernandez; C.Hurlbut

    2007-12-11

    Scintillation and waveshifter materials have been developed for the detection of ionizing radiation in an STTR program between Ludlum Measurements, Inc. and the University of Notre Dame. Several new waveshifter materials have been developed which are comparable in efficiency and faster in fluorescence decay than the standard material Y11 (K27) used in particle physics for several decades. Additionally, new scintillation materials useful for fiber tracking have been developed which have been compared to 3HF. Lastly, work was done on developing liquid scintillators and paint-on scintillators and waveshifters for high radiation environments.

  4. [Cancer risk associated to ionizing radiation].

    PubMed

    Laurier, Dominique; Hill, Catherine

    2013-10-01

    This article presents an update of the available data on the risk of cancer associated with exposure to ionizing radiation. The epidemiological studies conducted or continued during the last 10 years have led to improved quantification of radiation induced risks at low dose levels, notably by extension of the follow-up duration. The results comfort the underlying hypotheses of the radiation protection system in use. In particular, they show the existence of an increased risk for doses below 100 mSv of for exposures protracted over time. These results highlight the relevance of measures to reduce all exposures: accidental, medical, occupational or natural, and reinforce the importance of a prudent use of medical radiation, particularly for children. PMID:24298833

  5. Method and apparatus to monitor a beam of ionizing radiation

    SciTech Connect

    Blackburn, Brandon W.; Chichester, David L.; Watson, Scott M.; Johnson, James T.; Kinlaw, Mathew T.

    2015-06-02

    Methods and apparatus to capture images of fluorescence generated by ionizing radiation and determine a position of a beam of ionizing radiation generating the fluorescence from the captured images. In one embodiment, the fluorescence is the result of ionization and recombination of nitrogen in air.

  6. Mutational signatures of ionizing radiation in second malignancies.

    PubMed

    Behjati, Sam; Gundem, Gunes; Wedge, David C; Roberts, Nicola D; Tarpey, Patrick S; Cooke, Susanna L; Van Loo, Peter; Alexandrov, Ludmil B; Ramakrishna, Manasa; Davies, Helen; Nik-Zainal, Serena; Hardy, Claire; Latimer, Calli; Raine, Keiran M; Stebbings, Lucy; Menzies, Andy; Jones, David; Shepherd, Rebecca; Butler, Adam P; Teague, Jon W; Jorgensen, Mette; Khatri, Bhavisha; Pillay, Nischalan; Shlien, Adam; Futreal, P Andrew; Badie, Christophe; McDermott, Ultan; Bova, G Steven; Richardson, Andrea L; Flanagan, Adrienne M; Stratton, Michael R; Campbell, Peter J

    2016-01-01

    Ionizing radiation is a potent carcinogen, inducing cancer through DNA damage. The signatures of mutations arising in human tissues following in vivo exposure to ionizing radiation have not been documented. Here, we searched for signatures of ionizing radiation in 12 radiation-associated second malignancies of different tumour types. Two signatures of somatic mutation characterize ionizing radiation exposure irrespective of tumour type. Compared with 319 radiation-naive tumours, radiation-associated tumours carry a median extra 201 deletions genome-wide, sized 1-100 base pairs often with microhomology at the junction. Unlike deletions of radiation-naive tumours, these show no variation in density across the genome or correlation with sequence context, replication timing or chromatin structure. Furthermore, we observe a significant increase in balanced inversions in radiation-associated tumours. Both small deletions and inversions generate driver mutations. Thus, ionizing radiation generates distinctive mutational signatures that explain its carcinogenic potential. PMID:27615322

  7. Effects of ionizing radiation on CCD's

    NASA Technical Reports Server (NTRS)

    Hartsell, G. A.; Robinson, D. A.; Collins, D. R.

    1975-01-01

    The effects of 1.2 MeV gamma radiation and 20 MeV electrons on the operational characteristics of CCDs are studied. The effects of ionizing radiation on the charge transfer efficiency, dark current, and input/output circuitry are described. The improved radiation hardness of buried channel CCDs is compared to surface channel results. Both ion implanted and epitaxial layer buried channel device results are included. The advantages of using a single thickness SiO2 gate dielectric are described. The threshold voltage shifts and surface state density changes of dry, steam, and HCl doped oxides are discussed. Recent results on the recovery times and total dose effects of high dose rate pulses of 20 MeV electrons are reported.

  8. Measuring ionizing radiation with a mobile device

    NASA Astrophysics Data System (ADS)

    Michelsburg, Matthias; Fehrenbach, Thomas; Puente León, Fernando

    2012-02-01

    In cases of nuclear disasters it is desirable to know one's personal exposure to radioactivity and the related health risk. Usually, Geiger-Mueller tubes are used to assess the situation. Equipping everyone with such a device in a short period of time is very expensive. We propose a method to detect ionizing radiation using the integrated camera of a mobile consumer device, e.g., a cell phone. In emergency cases, millions of existing mobile devices could then be used to monitor the exposure of its owners. In combination with internet access and GPS, measured data can be collected by a central server to get an overview of the situation. During a measurement, the CMOS sensor of a mobile device is shielded from surrounding light by an attachment in front of the lens or an internal shutter. The high-energy radiation produces free electrons on the sensor chip resulting in an image signal. By image analysis by means of the mobile device, signal components due to incident ionizing radiation are separated from the sensor noise. With radioactive sources present significant increases in detected pixels can be seen. Furthermore, the cell phone application can make a preliminary estimate on the collected dose of an individual and the associated health risks.

  9. Modulation of apoptosis of eckol against ionizing radiation in mice

    SciTech Connect

    Park, Eunjin; Lee, Nam Ho; Joo, Hong-Gu; Jee, Youngheun

    2008-08-08

    To investigate the radioprotective potential of eckol, a component of the seaweed Ecklonia cava, against radiation in vivo, we evaluated the effect of eckol on cyto- and histo-protective capability of the lymphocytes and intestine against damage induced by a single whole body irradiation (WBI) in vivo. Here, we ascertained that eckol protected the lymphocytes' viability and rescued intestinal cells from radiation-induced apoptosis by decreasing the amount of pro-apoptotic p53 and Bax and increasing that of anti-apoptotic Bcl-2. These findings indicate that the overexpression of anti-apoptotic protein, which may lead to resistance to DNA damage, is involved deeply in protection of gastrointestinal cells after irradiation. Thus, eckol that can protect cells and tissues against ionizing radiation may have considerable potential as adjuncts to successful radiotherapy.

  10. Ionizing radiation and the developing brain

    SciTech Connect

    Schull, W.J.; Norton, S.; Jensh, R.P. )

    1990-05-01

    The unique susceptibility of the central nervous system to radiation exposure is attributable to its extensive period of development, the vulnerability of its neuronal cells, the migratory activity of many of its cells, its inability to replace mature neurons, and the complexity of the system itself. Radiation effects may be due to glial or neuronal cell death, interruption of migratory activity, impaired capacity to establish correct connections among cells, and/or alterations in dendritic development. These structural changes are often manifested as behavioral alterations later in life. Sensitivity to radiation (dose-response) is markedly similar among all mammalian species when developmental periods are compared. This review compares and contrasts human and animal behavioral data. Neonatal and postnatal adult behavioral tests have been shown to be sensitive, noninvasive measures of prenatal radiation exposure, although currently their predictive validity for humans is uncertain. Additional research is needed to determine the presence and significance of postnatal morphologic and functional alterations due to prenatal exposure to low levels of ionizing radiation.75 references.

  11. Altered microRNA expression profiles are involved in resistance to low-dose ionizing radiation in the absence of BMI1 in human dermal fibroblasts.

    PubMed

    Bae, Seunghee; Kim, Karam; Cha, Hwa Jun; Choi, Yeongmin; Shin, Shang Hun; An, In-Sook; Lee, Jae Ho; Song, Jie-Young; Yang, Kwang Hee; Nam, Seon Young; An, Sungkwan

    2014-10-01

    The polycomb group RING finger protein, B-cell‑specific moloney murine leukemia virus integration site 1 (BMI1), has emerged as a key regulator of cell proliferation, cell cycle, cell immortalization, chemoresistance and radioresistance. Although the radioresistant effect of BMI1 has been thoroughly investigated, the effectiveness of this factor on low-dose radiation (LDR) resistance has not been explored. Here, we demonstrate that BMI1 is not critical for altering cell viability or cell growth in response to LDR, but BMI1 changes cellular gene expression profiles in response to LDR. Normal human dermal fibroblasts (NHDFs) stably expressing BMI1 short hairpin RNA (shRNA) did not exhibit changes in cell viability or cell cycle distribution assays following exposure to 0.1 Gy of γ-radiation. However, microRNA (miRNA) microarrays revealed that a lack of BMI1 leads to changes in miRNA expression in response to LDR. Bioinformatics analyses demonstrated that predicted target genes of the altered miRNAs are functionally involved in both negative and positive regulation of cell growth, cell proliferation, cell cycle and apoptosis. Therefore, these results indicate that low radiosensitivity even in the absence of the radioresistant factor BMI1 is related with the altered miRNA expression profiles in NHDF. PMID:25016973

  12. Protection against ionizing radiation with eicosanoids

    SciTech Connect

    Steel, L.K.; Catravas, G.N.

    1988-01-01

    Prostaglandins (PGs) are extremely diverse in their pharmacological activities. They exhibit both antagonistic as well as cytoprotective properties in the pathogenesis of inflammation. Participation of PGs as chemical mediators in the regulation of immune responses and inflammation are increasingly apparent. The antagonistic properties of PGs have been implicated in a variety of symptoms resulting from exposure to ionizing radiation. Post-irradiation increases in small bowel motility, diarrhea, flatulence, abdominal pain, mucositis, and esophagitis have been attributed, in part, to excessive PG production. In contrast, exogenous PGs, particularly of the E type, have been shown to be cytoprotective against a variety of damaging agents, and a deficiency of endogeneous PG has been suggested to contribute to increase susceptibility to injury. These findings have provided much of the impetus to examine the potential cytoprotective effects of PGs in radiation injury.

  13. Degradation of cyanobacterial biosignatures by ionizing radiation.

    PubMed

    Dartnell, Lewis R; Storrie-Lombardi, Michael C; Mullineaux, Conrad W; Ruban, Alexander V; Wright, Gary; Griffiths, Andrew D; Muller, Jan-Peter; Ward, John M

    2011-12-01

    Primitive photosynthetic microorganisms, either dormant or dead, may remain today on the martian surface, akin to terrestrial cyanobacteria surviving endolithically in martian analog sites on Earth such as the Antarctic Dry Valleys and the Atacama Desert. Potential markers of martian photoautotrophs include the red edge of chlorophyll reflectance spectra or fluorescence emission from systems of light-harvesting pigments. Such biosignatures, however, would be modified and degraded by long-term exposure to ionizing radiation from the unshielded cosmic ray flux onto the martian surface. In this initial study into this issue, three analytical techniques--absorbance, reflectance, and fluorescence spectroscopy--were employed to determine the progression of the radiolytic destruction of cyanobacteria. The pattern of signal loss for chlorophyll reflection and fluorescence from several biomolecules is characterized and quantified after increasing exposures to ionizing gamma radiation. This allows estimation of the degradation rates of cyanobacterial biosignatures on the martian surface and the identification of promising detectable fluorescent break-down products. PMID:22149884

  14. Organic materials and devices for detecting ionizing radiation

    DOEpatents

    Doty, F. Patrick; Chinn, Douglas A.

    2007-03-06

    A .pi.-conjugated organic material for detecting ionizing radiation, and particularly for detecting low energy fission neutrons. The .pi.-conjugated materials comprise a class of organic materials whose members are intrinsic semiconducting materials. Included in this class are .pi.-conjugated polymers, polyaromatic hydrocarbon molecules, and quinolates. Because of their high resistivities (.gtoreq.10.sup.9 ohmcm), these .pi.-conjugated organic materials exhibit very low leakage currents. A device for detecting and measuring ionizing radiation can be made by applying an electric field to a layer of the .pi.-conjugated polymer material to measure electron/hole pair formation. A layer of the .pi.-conjugated polymer material can be made by conventional polymer fabrication methods and can be cast into sheets capable of covering large areas. These sheets of polymer radiation detector material can be deposited between flexible electrodes and rolled up to form a radiation detector occupying a small volume but having a large surface area. The semiconducting polymer material can be easily fabricated in layers about 10 .mu.m to 100 .mu.m thick. These thin polymer layers and their associated electrodes can be stacked to form unique multi-layer detector arrangements that occupy small volume.

  15. Untargeted metabolite profiling reveals that nitric oxide bioynthesis is an endogenous modulator of carotenoid biosynthesis in Deinococcus radiodurans and is required for extreme ionizing radiation resistance.

    PubMed

    Hansler, Alex; Chen, Qiuying; Ma, Yuliang; Gross, Steven S

    2016-01-01

    Deinococcus radiodurans (Drad) is the most radioresistant organism known. Although mechanisms that underlie the extreme radioresistance of Drad are incompletely defined, resistance to UV irradiation-induced killing was found to be greatly attenuated in an NO synthase (NOS) knockout strain of Drad (Δnos). We now show that endogenous NO production is also critical for protection of Drad against γ-irradiation (3000 Gy), a result of accelerated growth recovery, not protection against killing. NO-donor treatment rescued radiosensitization in Δnos Drad but did not influence radiosensitivity in wild type Drad. To discover molecular mechanisms by which endogenous NO confers radioresistance, metabolite profiling studies were performed. Untargeted LC-MS-based metabolite profiling in Drad quantified relative abundances of 1425 molecules and levels of 294 of these were altered by >5-fold (p < 0.01). Unexpectedly, these studies identified a dramatic perturbation in carotenoid biosynthetic intermediates in Δnos Drad, including a reciprocal switch in the pathway end-products from deoxydeinoxanthin to deinoxanthin. NO supplementation rescued these nos deletion-associated changes in carotenoid biosynthesis, and fully-restored radioresistance to wildtype levels. Because carotenoids were shown to be important contributors to radioprotection in Drad, our findings suggest that endogenously-produced NO serves to maintain a spectrum of carotenoids critical for Drad's ability to withstand radiation insult. PMID:26550929

  16. Decontamination of pesticide packing using ionizing radiation

    NASA Astrophysics Data System (ADS)

    Duarte, C. L.; Mori, M. N.; Kodama, Yasko; Oikawa, H.; Sampa, M. H. O.

    2007-11-01

    The Brazilian agriculture activities have consumed about 288,000 tons of pesticides per year conditioned in about 107,000,000 packing with weight of approximately 23,000 tons. The discharge of empty plastic packing of pesticides can be an environmental concern causing problems to human health, animals, and plants if done without inspection and monitoring. The objective of this work is to study the ionizing radiation effect in the main pesticides used in Brazil for plastic packing decontamination. Among the commercial pesticides, chlorpyrifos has significant importance because of its wide distribution and extensive use and persistence. The radiation-induced degradation of chlorpyrifos in liquid samples and in polyethylene pack was studied by gamma radiolysis. Packing of high-density polyethylene (HDPE) three layer coextruded, named COEX, contaminated with chlorpyrifos, were irradiated using both a multipurpose Co-60 gamma irradiator and a gamma source with 5000 Ci total activity Gamma cell type. The chemical analysis of the chlorpyrifos was made using a gas chromatography associated to the Mass Spectrometry—GCMS from Shimadzu Model QP 5000. Gamma radiation was efficient for removing chlorpyrifos from the plastic packing, in all studied cases.

  17. Enhanced radiation resistant fiber optics

    DOEpatents

    Lyons, Peter B.; Looney, Larry D.

    1993-01-01

    A process for producing an optical fiber having enhanced radiation resitance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation.

  18. Head Resistance Due to Radiators

    NASA Technical Reports Server (NTRS)

    Kleinschmidt, R V; Parsons, S R

    1920-01-01

    Part 1 deals with the head resistance of a number of common types of radiator cores at different speeds in free air, as measured in the wind tunnel at the bureau of standards. This work was undertaken to determine the characteristics of various types of radiator cores, and in particular to develop the best type of radiator for airplanes. Some 25 specimens of core were tested, including practically all the general types now in use, except the flat plate type. Part 2 gives the results of wind tunnel tests of resistance on a model fuselage with a nose radiator. Part 3 presents the results of preliminary tests of head resistance of a radiator enclosed in a streamlined casing. Special attention is given to the value of wing radiator and of the radiator located in the open, especially when it is provided with a properly designed streamlined casing.

  19. Radiation Resistances of Dielectric Liquids

    NASA Technical Reports Server (NTRS)

    Bouquet, Frank L.; Somoano, Robert B.

    1987-01-01

    Report presents data on effects of ionizing radiation on dielectric liquids for high-energy-density, pulsed-power capacitors. Based on Jet Propulsion Laboratory test results, search of NASA and Department of Energy computer files, survey of open literature, and contacts with manufacturers and suppliers. Covers 22 organic liquids, although detailed data found for only one compound, polydimethyl siloxane. Generic data on effects of radiation on compounds with similar chemical structures provided where data on specific compounds lacking.

  20. The impact of ionizing radiation on placental trophoblasts

    PubMed Central

    Kanter, D.J.; O'Brien, M.B.; Shi, X.-H.; Chu, T.; Mishima, T.; Beriwal, S.; Epperly, M.W.; Wipf, P.; Greenberger, J.S.; Sadovsky, Y.

    2014-01-01

    Introduction Exposure to low-dose radiation is widespread and attributable to natural sources. However, occupational, medical, accidental, and terrorist-related exposures remain a significant threat. Information on radiation injury to the feto-placental unit is scant and largely observational. We hypothesized that radiation causes trophoblast injury, and alters the expression of injury-related transcripts in vitro or in vivo, thus affecting fetal growth. Methods Primary human trophoblasts (PHTs), BeWo or NCCIT cells were irradiated in vitro, and cell number and viability were determined. Pregnant C57Bl/6HNsd mice were externally irradiated on E13.5, and placentas examined on E17.5. RNA expression was analyzed using microarrays and RT-qPCR. The experiments were repeated in the presence of the gramicidin S (GS)-derived nitroxide JP4-039, used to mitigate radiation-induced cell injury. Results We found that survival of in vitro–irradiated PHT cell was better than that of irradiated BeWo trophoblast cell line or the radiosensitive NCCIT mixed germ cell tumor line. Radiation altered the expression of several trophoblast genes, with a most dramatic effect on CDKN1A (p21, CIP1). Mice exposed to radiation at E13.5 exhibited a 25% reduction in mean weight by E17.5, and a 9% reduction in placental weight, which was associated with relatively small changes in placental gene expression. JP4-039 had a minimal effect on feto-placental growth or on gene expression in irradiated PHT cells or mouse placenta. Discussion and conclusion While radiation affects placental trophoblasts, the established placenta is fairly resistant to radiation, and changes in this tissue may not fully account for fetal growth restriction induced by ionizing radiation. PMID:24418702

  1. Effects of prenatal exposure to ionizing radiation

    SciTech Connect

    Miller, R.W. )

    1990-07-01

    Prenatal exposure to ionizing radiation induces some effects that are seen at birth and others that cannot be detected until later in life. Data from A-bomb survivors in Hiroshima and Nagasaki show a diminished number of births after exposure under 4 wk of gestational age. Although a wide array of congenital malformations has been found in animal experimentation after such exposure to x rays, in humans only small head size (exposure at 4-17 wk) and mental retardation (exposure primarily at 8-15 wk) have been observed. In Hiroshima, small head size occurred after doses of 0.10-0.19 Gy or more, and an excess of mental retardation at 0.2-0.4 Gy or more. Intelligence test scores were reduced among A-bomb survivors exposed at 8-15 wk of gestational age by 21-29 IQ points per Gy. Other effects of in-utero exposure to atomic radiation include long-lasting complex chromosome abnormalities.

  2. Hematologic consequences of exposure to ionizing radiation.

    PubMed

    Dainiak, Nicholas

    2002-06-01

    From the early 1900s, it has been known that ionizing radiation (IR) impairs hematopoiesis through a variety of mechanisms. IR exposure directly damages hematopoietic stem cells and alters the capacity of bone marrow stromal elements to support and/or maintain hematopoiesis in vivo and in vitro. Exposure to IR induces dose-dependent declines in circulating hematopoietic cells not only through reduced bone marrow production, but also by redistribution and apoptosis of mature formed elements of the blood. Recently, the importance of using lymphocyte depletion kinetics to provide a "crude" dose estimate has been emphasized, particularly in rapid assessment of large numbers of individuals who may be exposed to IR through acts of terrorism or by accident. A practical strategy to estimate radiation dose and triage victims based upon clinical symptomatology is presented. An explosion of knowledge has occurred regarding molecular and cellular pathways that trigger and mediate hematologic responses to IR. In addition to damaging DNA, IR alters gene expression and transcription, and interferes with intracellular and intercellular signaling pathways. The clinical expression of these disturbances may be the development of leukemia, the most significant hematologic complication of IR exposure among survivors of the atomic bomb detonations over Japan. Those at greatest risk for leukemia are individuals exposed during childhood. The association of leukemia with chronic, low-dose-rate exposure from nuclear power plant accidents and/or nuclear device testing has been more difficult to establish, due in part to lack of precision and sensitivity of methods to assess doses that approach background radiation dose. Nevertheless, multiple myeloma may be associated with chronic exposure, particularly in those exposed at older ages. PMID:12063018

  3. The effect of recombination radiation on the temperature and ionization state of partially ionized gas

    NASA Astrophysics Data System (ADS)

    Raičević, Milan; Pawlik, Andreas H.; Schaye, Joop; Rahmati, Alireza

    2014-01-01

    A substantial fraction of all ionizing photons originate from radiative recombinations. However, in radiative transfer calculations this recombination radiation is often assumed to be absorbed `on-the-spot' because for most methods the computational cost associated with the inclusion of gas elements as sources is prohibitive. We present a new, CPU and memory efficient implementation for the transport of ionizing recombination radiation in the TRAPHIC radiative transfer scheme. TRAPHIC solves the radiative transfer equation by tracing photon packets at the speed of light and in a photon-conserving manner in spatially adaptive smoothed particle hydrodynamics simulations. Our new implementation uses existing features of the TRAPHIC scheme to add recombination radiation at no additional cost in the limit in which the fraction of the simulation box filled with radiation approaches 1. We test the implementation by simulating an H II region in photoionization equilibrium and comparing to reference solutions presented in the literature, finding excellent agreement. We apply our implementation to discuss the evolution of the H II region to equilibrium. We show that the widely used case A and B approximations yield accurate ionization profiles only near the source and near the ionization front, respectively. We also discuss the impact of recombination radiation on the geometry of shadows behind optically thick absorbers. We demonstrate that the shadow region may be completely ionized by the diffuse recombination radiation field and discuss the important role of heating by recombination radiation in the shadow region.

  4. Ionizing radiation detection using microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    DeHaven, Stanton

    Ionizing radiation detecting microstructured optical fibers are fabricated, modeled and experimentally measured for X-ray detection in the 10-40 keV energy range. These fibers operate by containing a scintillator material which emits visible light when exposed to ionizing radiation. An X-ray source characterized with a CdTe spectrometer is used to quantify the X-ray detection efficiency of the fibers. The solid state CdTe detector is considered 100% efficient in this energy range. A liquid filled microstructured optical fiber (MOF) is presented where numerical analysis and experimental observation leads to a geometric theory of photon transmission using total internal reflection. The model relates the quantity and energy of absorbed X-rays to transmitted and measured visible light photons. Experimental measurement of MOF photon counts show good quantitative agreement with calculated theoretical values. This work is extended to a solid organic scintillator, anthracene, which shows improved light output due to its material properties. A detailed description of the experimental approach used to fabricate anthracene MOF is presented. The fabrication technique uses a modified Bridgman-Stockbarger crystal growth technique to grow anthracene single crystals inside MOF. The anthracene grown in the MOF is characterized using spectrophotometry, Raman spectroscopy, and X-ray diffraction. These results show the anthracene grown is a high purity crystal with a structure similar to anthracene grown from the liquid, vapor and melt techniques. The X-ray measurement technique uses the same approach as that for liquid filled MOF for efficiency comparison. A specific fiber configuration associated with the crystal growth allows an order of magnitude improvement in X-ray detection efficiency. The effect of thin film external coatings on the measured efficiency is presented and related to the fiber optics. Lastly, inorganic alkali halide scintillator materials of CsI(Tl), CsI(Na), and

  5. Radiation damage to tetramethlysilane and tetramethlygermanium ionization chambers

    NASA Astrophysics Data System (ADS)

    Hoshi, Y.; Higuchi, M.; Oyama, K.; Akaishi, H.; Yuta, H.; Abe, K.; Hasegawa, K.; Suekane, F.; Nagamine, T.; Kawamura, N.

    1994-08-01

    Two detector media suitable for a warm liquid, ionization chamber filled with tetramethylsilane(TMS) and tetramethylgermanium(TMG) were exposed to y radiation from a (sup 60)Co source up to dose 579Gray and 902Gray, respectively. The electron lifetimes and the free ion yields were measured as a function of accumulated radiation dose. A similar behavior of the electron lifetimes and the free ion yields with increasing radiation dose was observed between the TMS and TMG ionization chambers.

  6. Astrophysical Ionizing Radiation Sources and Life on Earth

    NASA Astrophysics Data System (ADS)

    Thomas, Brian

    2013-04-01

    Astrophysical sources of ionizing radiation have been recognized as a potential threat to life on Earth, primarily through long-term depletion of stratospheric ozone, leading to greatly increased solar ultraviolet (UV) irradiance at the surface. It has been suggested that a gamma-ray burst, in particular, may have initiated the late Ordovician mass extinction - one of the ``big five'' known extinctions. I will describe the atmospheric impacts of ionizing radiation events and discuss estimates of biological damage under a severely depleted ozone layer. In particular, I will describe new and on-going work to quantify the impact of ionizing radiation events on primary producers in Earth's oceans.

  7. The susceptibility of TaOx-based memristors to high dose rate ionizing radiation and total ionizing dose

    DOE PAGESBeta

    McLain, Michael Lee; Sheridan, Timothy J.; Hjalmarson, Harold Paul; Mickel, Patrick R.; Hanson, Donald J.; McDonald, Joseph K.; Hughart, David Russell; Marinella, Matthew J.

    2014-11-11

    This paper investigates the effects of high dose rate ionizing radiation and total ionizing dose (TID) on tantalum oxide (TaOx) memristors. Transient data were obtained during the pulsed exposures for dose rates ranging from approximately 5.0 ×107 rad(Si)/s to 4.7 ×108 rad(Si)/s and for pulse widths ranging from 50 ns to 50 μs. The cumulative dose in these tests did not appear to impact the observed dose rate response. Static dose rate upset tests were also performed at a dose rate of ~3.0 ×108 rad(Si)/s. This is the first dose rate study on any type of memristive memory technology. Inmore » addition to assessing the tolerance of TaOx memristors to high dose rate ionizing radiation, we also evaluated their susceptibility to TID. The data indicate that it is possible for the devices to switch from a high resistance off-state to a low resistance on-state in both dose rate and TID environments. The observed radiation-induced switching is dependent on the irradiation conditions and bias configuration. Furthermore, the dose rate or ionizing dose level at which a device switches resistance states varies from device to device; the enhanced susceptibility observed in some devices is still under investigation. As a result, numerical simulations are used to qualitatively capture the observed transient radiation response and provide insight into the physics of the induced current/voltages.« less

  8. Radiation resistance of acinetobacter spp.

    NASA Astrophysics Data System (ADS)

    Whitby, James L.

    1995-02-01

    The radiation resistance of 78 different strains of Acinetobacter sp. 42 from clinical isolates and 36 from other sources were compared with 15 clinical isolates and 12 other strains from Denmark. None of the Canadian strains was as resistant as resistant-enhanced Danish strains. Four strains had D 10 values of 3.1-3.6 kGy. Irradiated and unirradiated cells from all strains grew well, when cultured in Trypticase-Soy Broth at 30°C. Most cultures grew after overnight incubation. It was concluded that there would be no difficulty in detecting these strains, using ISO methodology for establishing the radiation sterilization dose for devices.

  9. Novel fibre-optic-based ionization radiation probes

    NASA Astrophysics Data System (ADS)

    Jackson, David A.

    2004-06-01

    CsI ionization radiation probes interrogated via a fiber optic transceiver link for monitoring medical procedures such as Intensity Modulated Radiotherapy, Brachytherapy and Nuclear Medicine are presented together with potential industrial, environmental and military applications.

  10. Ionizing radiation calculations and comparisons with LDEF data

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.; Watts, J. W., Jr.

    1992-01-01

    In conjunction with the analysis of LDEF ionizing radiation dosimetry data, a calculational program is in progress to aid in data interpretation and to assess the accuracy of current radiation models for future mission applications. To estimate the ionizing radiation environment at the LDEF dosimeter locations, scoping calculations for a simplified (one dimensional) LDEF mass model were made of the primary and secondary radiations produced as a function of shielding thickness due to trapped proton, galactic proton, and atmospheric (neutron and proton cosmic ray albedo) exposures. Preliminary comparisons of predictions with LDEF induced radioactivity and dose measurements were made to test a recently developed model of trapped proton anisotropy.

  11. Effects of hindlimb unloading and ionizing radiation on skeletal muscle resistance artery vasodilation and its relation to cancellous bone in mice.

    PubMed

    Prisby, Rhonda D; Alwood, Joshua S; Behnke, Brad J; Stabley, John N; McCullough, Danielle J; Ghosh, Payal; Globus, Ruth K; Delp, Michael D

    2016-01-15

    Spaceflight has profound effects on vascular function as a result of weightlessness that may be further compounded by radiation exposure. The purpose of the present study was to assess the individual and combined effects of hindlimb unloading (HU) and radiation (Rad) on vasodilator responses in the skeletal muscle vasculature. Adult male C57BL/6J mice were randomized to one of four groups: control (Con), HU (tail suspension for 15 days), Rad (200 cGy of (137)Cs), and HU-Rad (15-day tail suspension and 200 cGy of (137)Cs). Endothelium-dependent vasodilation of gastrocnemius feed arteries was assessed in vitro using acetylcholine (ACh, 10(-9)-10(-4) M) and inhibitors of nitric oxide synthase (NOS) and cyclooxygenase (COX). Endothelium-independent vasodilation was assessed using Dea-NONOate (10(-9)-10(-4) M). Endothelium-dependent and -independent vasodilator responses were impaired relative to Con responses in all treatment groups; however, there was no further impairment from the combination of treatments (HU-Rad) relative to that in the HU and Rad groups. The NOS-mediated contribution to endothelium-dependent vasodilation was depressed with HU and Rad. This impairment in NOS signaling may have been partially compensated for by an enhancement of PGI2-mediated dilation. Changes in endothelium-dependent vasodilation were also associated with decrements in trabecular bone volume in the proximal tibia metaphysis. These data demonstrate that the simulated space environment (i.e., radiation exposure and unloading of muscle and bone) significantly impairs skeletal muscle artery vasodilation, mediated through endothelium-dependent reductions in NOS signaling and decrements in vascular smooth muscle cell responsiveness to NO. PMID:26472865

  12. 2.2.2 Non-Ionizing Radiations

    NASA Astrophysics Data System (ADS)

    Bernhardt, J. H.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.2.2 Non-Ionizing Radiations' of the Section '2.2 Kinds of Radiation' of the Chapter '2 Radiation and Biological Effects' with the contents:

  13. Melanoma and ionizing radiation: is there a causal relationship?

    PubMed

    Fink, Christopher A; Bates, Michael N

    2005-11-01

    This review was initiated in response to concerns that ionizing radiation could be a cause of melanoma. Studies presenting the relative risks for melanoma after external ionizing radiation exposure were in seven categories: (1) The Canadian Radiation Dose Registry, (2) nuclear industry workers, (3) subjects near nuclear test blasts, (4) survivors of the atomic bombings of Japan, (5) airline pilots and cabin attendants, (6) recipients of medical radiation, and (7) radiological technicians. Relative risks for leukemia in each of the studies were used to confirm the likelihood of exposure to ionizing radiation. When studies within a category were compatible, meta-analytic methods were used to obtain combined estimates of the relative risk, and a meta-regression analysis of melanoma relative risk compared to leukemia relative risk was used to examine consistency across exposure categories. Generally, exposure categories with elevated relative risks of leukemia had proportionately elevated relative risks of melanoma. This suggests that people exposed to ionizing radiation may be at increased risk of developing melanoma, although alternative explanations are possible. Future epidemiological studies of ionizing radiation effects should include melanoma as an outcome of interest. PMID:16238450

  14. Effects of ionizing radiation on extracellular matrix

    NASA Astrophysics Data System (ADS)

    Mohamed, F.; Bradley, D. A.; Winlove, C. P.

    2007-09-01

    The extracellular matrix is a ubiquitous and important component of tissues. We investigated the effects of ionizing radiation on the physical properties of its principal macromolecular components, pericardial collagen, ligament elastin and hyaluronan, a representative glycosaminoglycan. Samples were exposed to X-rays from an electron linear accelerator in the range of 10-100 Gy to cover the range of irradiation exposure during radiotherapy. A uniaxial mechanical testing protocol was used to characterize the fibrous proteins. For pericardial tissue the major change was an increase in the elastic modulus in the toe region of the curve (⩽20% strain), from 23±18 kPa for controls to 57±22 kPa at a dose of 10 Gy ( p=0.01, α=0.05). At larger strain (⩾20% strain), the elastic modulus in the linear region decreased from 1.92±0.70 MPa for control pericardium tissue to 1.31±0.56 MPa ( p=0.01, α=0.05) for 10 Gy X-irradiated sample. Similar observations have been made previously on tendon collagen at larger strains. For elastin, the stress-strain relationship was linear up to 30% strain, but the elastic modulus decreased significantly with irradiation (controls 626±65 kPa, irradiated 474±121 kPa ( p=0.02, α=0.05), at 10 Gy X-irradiation). The results suggest that for collagen the primary effect of irradiation is generation of additional cross-links, while for elastin chain scissions are important. The viscosity of HA (at 1.25% w/v and 0.125% w/v) was measured by both cone and plate and capillary viscometry, the former providing measurement at uniform shear rate and the latter providing a more sensitive indication of changes at low viscosity. Both techniques revealed a dose-dependent reduction in viscosity (from 3400±194 cP for controls to 1500±88 cP at a shear rate of 2 s -1 and dose of 75 Gy), again suggesting depolymerization.

  15. Ionizing Radiation: The Good, the Bad, and the Ugly

    PubMed Central

    Ryan, Julie L.

    2013-01-01

    Skin changes from ionizing radiation have been scientifically documented since 1902 (Hymes et al., 2006). Ionizing radiation is a widely accepted form of treatment for various types of cancer. Despite the technological advances, radiation skin injury remains a significant problem. This injury, often referred to as radiation dermatitis, occurs in about 95% of patients receiving radiation therapy for cancer and ranges in severity from mild erythema to moist desquamation and ulceration (McQuestion, 2011; Salvo et al., 2010). Ionizing radiation is not only a concern for cancer patients, but also a public health concern due to the potential for and reality of a nuclear and/or radiological event. Recently, the United States has increased efforts to develop medical countermeasures to protect against radiation toxicities from acts of bioterrorism, as well as cancer treatment. Management of radiation dermatitis would improve the therapeutic benefit of radiation therapy for cancer and potentially the mortality expected in any “dirty bomb” attack (Benderitter et al., 2010; Muller and Meineke, 2010). Currently, there is no effective treatment to prevent or mitigate radiation skin injury. This review summarizes “the good, the bad and the ugly” of current and evolving knowledge regarding mechanisms of and treatments for radiation skin injury. PMID:22217743

  16. Effects of ionizing radiation on selected optical materials: An overview

    SciTech Connect

    Wirtenson, G.R.; White, R.H.

    1992-07-30

    This report gives an overview of the effects of ionizing radiation on optical materials that may be used in spacecraft sensors. It introduces the relevant phenomena and indicates were more detailed information can be found. The topics covered include radiation induced absorption in ultraviolet transmitting materials, ordinary optical glasses, cerium stabilized optical glasses, and infrared transmitting materials; bleaching and annealing, and radioluminesence.

  17. Advanced p-MOSFET Ionizing-Radiation Dosimeter

    NASA Technical Reports Server (NTRS)

    Buehler, Martin G.; Blaes, Brent R.

    1994-01-01

    Circuit measures total dose of ionizing radiation in terms of shift in threshold gate voltage of doped-channel metal oxide/semiconductor field-effect transistor (p-MOSFET). Drain current set at temperature-independent point to increase accuracy in determination of radiation dose.

  18. Effects of Ionizing Radiation on Postharvest Fungal Pathogens.

    PubMed

    Jeong, Rae-Dong; Shin, Eun-Jung; Chu, Eun-Hee; Park, Hae-Jun

    2015-06-01

    Postharvest diseases cause losses in a wide variety of crops around the world. Irradiation, a useful nonchemical approach, has been used as an alternative treatment for fungicide to control plant fungal pathogens. For a preliminary study, ionizing radiations (gamma, X-ray, or e-beam irradiation) were evaluated for their antifungal activity against Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer through mycelial growth, spore germination, and morphological analysis under various conditions. Different fungi exhibited different radiosensitivity. The inhibition of fungal growth showed in a dose-dependent manner. Three fungal pathogens have greater sensitivity to the e-beam treatment compared to gamma or X-ray irradiations. The inactivation of individual fungal-viability to different irradiations can be considered between 3-4 kGy for B. cinerea and 1-2 kGy for P. expansum and R. stolonifer based on the radiosensitive and radio-resistant species, respectively. These preliminary data will provide critical information to control postharvest diseases through radiation. PMID:26060436

  19. 29 CFR 1926.53 - Ionizing radiation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Protection Against Radiation (10 CFR part 20), relating to protection against occupational radiation exposure, shall apply. (b) Any activity which involves the use of radioactive materials or X-rays, whether or...

  20. 29 CFR 1926.53 - Ionizing radiation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Protection Against Radiation (10 CFR part 20), relating to protection against occupational radiation exposure, shall apply. (b) Any activity which involves the use of radioactive materials or X-rays, whether or...

  1. 29 CFR 1926.53 - Ionizing radiation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Protection Against Radiation (10 CFR part 20), relating to protection against occupational radiation exposure, shall apply. (b) Any activity which involves the use of radioactive materials or X-rays, whether or...

  2. Mammalian cells exposed to ionizing radiation: Structural and biochemical aspects.

    PubMed

    Sabanero, Myrna; Azorín-Vega, Juan Carlos; Flores-Villavicencio, Lérida Liss; Castruita-Dominguez, J Pedro; Vallejo, Miguel Angel; Barbosa-Sabanero, Gloria; Cordova-Fraga, Teodoro; Sosa-Aquino, Modesto

    2016-02-01

    Acute or chronic exposure to ionizing radiation is a factor that may be hazardous to health. It has been reported that exposure to low doses of radiation (less than 50 mSv/year) and subsequently exposure to high doses produces greater effects in people. It has been reported that people who have been exposed to low doses of radiation (less than 50 mSv/year) and subsequently are exposed to high doses, have greater effects. However, at a molecular and biochemical level, it is an unknown alteration. This study, analyzes the susceptibility of a biological system (HeLa ATCC CCL-2 human cervix cancer cell line) to ionizing radiation (6 and 60 mSv/90 s). Our research considers multiple variables such as: total protein profile, mitochondrial metabolic activity (XTT assay), cell viability (Trypan blue exclusion assay), cytoskeleton (actin microfilaments), nuclei (DAPI), and genomic DNA. The results indicate, that cells exposed to ionizing radiation show structural alterations in nuclear phenotype and aneuploidy, further disruption in the tight junctions and consequently on the distribution of actin microfilaments. Similar alterations were observed in cells treated with a genotoxic agent (200 μM H2O2/1h). In conclusion, this multi-criteria assessment enables precise comparisons of the effects of radiation between various line cells. However, it is necessary to determine stress markers for integration of the effects of ionizing radiation. PMID:26656429

  3. INDUSTRIAL EFFLUENT TREATMENT USING IONIZING RADIATION COMBINED TO TITANIUM DIOXIDE

    SciTech Connect

    Duarte, C.L.; Oikawa, H.; Mori, M.N.; Sampa, M.H.O.

    2004-10-04

    The Advanced Oxidation Process (AOP) with OH radicals are the most efficient to mineralize organic compounds, and there are various methods to generate OH radicals as the use of ozone, hydrogen peroxide and ultra-violet radiation and ionizing radiation. The irradiation of aqueous solutions with high-energy electrons results in the excitation and ionizing of the molecules and rapid (10{sup -14} - 10{sup -9} s) formation of reactive intermediates. These reactive species will react with organic compounds present in industrial effluent inducing their decomposition. Titanium dioxide (TiO{sub 2}) catalyzed photoreaction is used to remove a wide range of pollutants in air and water media, combined to UV/VIS light, FeO{sub 2}, and H{sub 2}O{sub 2}, but as far as known there is no report on the combination with ionizing radiation. In some recent studies, the removal of organic pollutants in industrial effluent, such as Benzene, Toluene, and Xylene from petroleum production using ionizing radiation was investigated. It has been ob served that none of the methods can be used individually in wastewater treatment applications with good economics and high degree of energy efficiency. In the present work, the efficiency of ionizing radiation in presence of TiO{sub 2} to treat industrial effluent was evaluated. The main aim to combine these technologies is to improve the efficiency for very hard effluents and to reduce the processing cost for future implementation to large-scale design.

  4. Synergistic effect of ozonation and ionizing radiation for PVA decomposition.

    PubMed

    Sun, Weihua; Chen, Lujun; Zhang, Yongming; Wang, Jianlong

    2015-08-01

    Ozonation and ionizing radiation are both advanced oxidation processes (AOPs) without chemical addition and secondary pollution. Also, the two processes' efficiency is determined by different pH conditions, which creates more possibilities for their combination. Importantly, the combined process of ozonation and ionizing radiation could be suitable for treating wastewaters with extreme pH values, i.e., textile wastewater. To find synergistic effects, the combined process of ozonation and ionizing radiation mineralization was investigated for degradation of polyvinyl alcohol (PVA) at different pH levels. A synergistic effect was found at initial pH in the range 3.0-9.4. When the initial pH was 3.0, the combined process of ozonation and ionizing radiation gave a PVA mineralization degree of 17%. This was 2.7 times the sum achieved by the two individual processes, and factors of 2.1 and 1.7 were achieved at initial pH of 7.0 and 9.4, respectively. The combined process of ozonation and ionizing radiation was demonstrated to be a feasible strategy for treatment of PVA-containing wastewater. PMID:26257347

  5. 2.3.1 Biological Effects of Ionizing Radiations

    NASA Astrophysics Data System (ADS)

    Kaul, A.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.3.1 Biological Effects of Ionizing Radiations' of the Section '2.3 Biological Effects' of the Chapter '2 Radiation and Biological Effects' with the comtents:

  6. MOSFET and MOS capacitor responses to ionizing radiation

    NASA Technical Reports Server (NTRS)

    Benedetto, J. M.; Boesch, H. E., Jr.

    1984-01-01

    The ionizing radiation responses of metal oxide semiconductor (MOS) field-effect transistors (FETs) and MOS capacitors are compared. It is shown that the radiation-induced threshold voltage shift correlates closely with the shift in the MOS capacitor inversion voltage. The radiation-induced interface-state density of the MOSFETs and MOS capacitors was determined by several techniques. It is shown that the presence of 'slow' states can interfere with the interface-state measurements.

  7. THE ESCAPE FRACTION OF IONIZING RADIATION FROM GALAXIES

    SciTech Connect

    Benson, Andrew; Venkatesan, Aparna; Shull, J. Michael E-mail: avenkatesan@usfca.edu

    2013-06-10

    The escape of ionizing radiation from galaxies plays a critical role in the evolution of gas in galaxies, and the heating and ionization history of the intergalactic medium. We present semi-analytic calculations of the escape fraction of ionizing radiation for both hydrogen and helium from galaxies ranging from primordial systems to disk-type galaxies that are not heavily dust-obscured. We consider variations in the galaxy density profile, source type, location, and spectrum, and gas overdensity/distribution factors. For sufficiently hard first-light sources, the helium ionization fronts closely track or advance beyond that of hydrogen. Key new results in this work include calculations of the escape fractions for He I and He II ionizing radiation, and the impact of partial ionization from X-rays from early active galactic nuclei or stellar clusters on the escape fractions from galaxy halos. When factoring in frequency-dependent effects, we find that X-rays play an important role in boosting the escape fractions for both hydrogen and helium, but especially for He II. We briefly discuss the implications of these results for recent observations of the He II reionization epoch at low redshifts, as well as the UV data and emission-line signatures from early galaxies anticipated from future satellite missions.

  8. The ionizing radiation environment in space and its effects

    SciTech Connect

    Adams, Jim; Falconer, David; Fry, Dan

    2012-11-20

    The ionizing radiation environment in space poses a hazard for spacecraft and space crews. The hazardous components of this environment are reviewed and those which contribute to radiation hazards and effects identified. Avoiding the adverse effects of space radiation requires design, planning, monitoring and management. Radiation effects on spacecraft are avoided largely though spacecraft design. Managing radiation exposures of space crews involves not only protective spacecraft design and careful mission planning. Exposures must be managed in real time. The now-casting and forecasting needed to effectively manage crew exposures is presented. The techniques used and the space environment modeling needed to implement these techniques are discussed.

  9. Future directions for LDEF ionizing radiation modeling and assessments

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1993-01-01

    A calculational program utilizing data from radiation dosimetry measurements aboard the Long Duration Exposure Facility (LDEF) satellite to reduce the uncertainties in current models defining the ionizing radiation environment is in progress. Most of the effort to date has been on using LDEF radiation dose measurements to evaluate models defining the geomagnetically trapped radiation, which has provided results applicable to radiation design assessments being performed for Space Station Freedom. Plans for future data comparisons, model evaluations, and assessments using additional LDEF data sets (LET spectra, induced radioactivity, and particle spectra) are discussed.

  10. Space Weather Nowcasting of Atmospheric Ionizing Radiation for Aviation Safety

    NASA Technical Reports Server (NTRS)

    Mertens, Christopher J.; Wilson, John W.; Blattnig, Steve R.; Solomon, Stan C.; Wiltberger, J.; Kunches, Joseph; Kress, Brian T.; Murray, John J.

    2007-01-01

    There is a growing concern for the health and safety of commercial aircrew and passengers due to their exposure to ionizing radiation with high linear energy transfer (LET), particularly at high latitudes. The International Commission of Radiobiological Protection (ICRP), the EPA, and the FAA consider the crews of commercial aircraft as radiation workers. During solar energetic particle (SEP) events, radiation exposure can exceed annual limits, and the number of serious health effects is expected to be quite high if precautions are not taken. There is a need for a capability to monitor the real-time, global background radiations levels, from galactic cosmic rays (GCR), at commercial airline altitudes and to provide analytical input for airline operations decisions for altering flight paths and altitudes for the mitigation and reduction of radiation exposure levels during a SEP event. The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) model is new initiative to provide a global, real-time radiation dosimetry package for archiving and assessing the biologically harmful radiation exposure levels at commercial airline altitudes. The NAIRAS model brings to bear the best available suite of Sun-Earth observations and models for simulating the atmospheric ionizing radiation environment. Observations are utilized from ground (neutron monitors), from the atmosphere (the METO analysis), and from space (NASA/ACE and NOAA/GOES). Atmospheric observations provide the overhead shielding information and the ground- and space-based observations provide boundary conditions on the GCR and SEP energy flux distributions for transport and dosimetry simulations. Dose rates are calculated using the parametric AIR (Atmospheric Ionizing Radiation) model and the physics-based HZETRN (High Charge and Energy Transport) code. Empirical models of the near-Earth radiation environment (GCR/SEP energy flux distributions and geomagnetic cut-off rigidity) are benchmarked

  11. Concerns with low-level ionizing radiation

    SciTech Connect

    Yalow, R.S.

    1994-12-31

    Populations have been studied in geographic areas of increased natural radiation, in radiation-exposed workers, in patients medically exposed, and in accidental exposures. No reproducible evidence exists of harmful effects from increases in background radiation three to ten times the usual levels. There is no increase in leukemia or other cancers among American military participants in nuclear testing, no increase in leukemia or thyroid cancer among medical patients receiving {sup 131}I for diagnosis or treatment of hypothyroidism, and no increase in lung cancer among nonsmokers exposed to increased radon in the home. The association of radiation with the atomic bomb and with excessive regulatory and health physics as-low-as-reasonably-achievable (ALARA) radiation levels practices has created a climate of fear about the dangers of radiation at any level. However, there is no evidence that radiation exposures at the levels equivalent to medical usage are harmful. The unjustified excessive concern with radiation at any level, however, precludes beneficial uses of radiation and radioactivity in medicine, science, and industry.

  12. Decomposition of persistent pharmaceuticals in wastewater by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Kimura, Atsushi; Osawa, Misako; Taguchi, Mitsumasa

    2012-09-01

    Pharmaceuticals in wastewater were treated by the combined method of activated sludge and ionizing radiation in laboratory scale. Oseltamivir, aspirin, and ibuprofen at 5 μmol dm-3 in wastewater were decomposed by the activated sludge at reaction time for 4 h. Carbamazepine, ketoprofen, mefenamic acid, clofibric acid, and diclofenac were not biodegraded completely, but were eliminated by γ-ray irradiation at 2 kGy. The rate constants of the reactions of these pharmaceuticals with hydroxyl radicals were estimated by the competition reaction method to be 4.0-10×109 mol-1 dm3 s-1. Decompositions of the pharmaceuticals in wastewater by ionizing radiation were simulated by use of the rate constants and the amount of total organic carbon as parameters. Simulation curves of concentrations of these pharmaceuticals as a function of dose described the experimental data, and the required dose for the elimination of them in wastewater by ionizing radiation can be estimated by this simulation.

  13. Ionization Parameter: A Diagnostic of Radiation Pressure Dominated HII Regions

    NASA Astrophysics Data System (ADS)

    Yeh, Sherry; Matzner, C. D.

    2011-01-01

    When irradiation is sufficiently intense, the structure of an HII region will be dominated by radiation pressure and stellar winds, rather than ionized gas pressure. This state is of considerable interest because of its role in the formation of massive stars, the disruption of giant molecular clouds, and the evolution of starburst galaxies. We discuss the usefulness of the ionization parameter U, as often derived from observed line ratios between species which exist only in ionized gas, as a diagnostic for the radiation pressure-dominated state. In ionization-bounded directions, U cannot exceed a maximum value Umax determined by equilibrium between radiation and gas pressure forces. Lower values of U will occur, however, when the pressure of shocked stellar winds is significant, or when neutral gas is broken into clumps with sufficiently small radii of curvature. Applying these considerations to a prominent ionized shell around 30 Doradus and to the inner starburst region of M82, along with Cloudy simulations, we conclude that both are dominated by a combination of radiation pressure and shocked winds.

  14. Influence of Dust Loading on Atmospheric Ionizing Radiation on Mars

    NASA Technical Reports Server (NTRS)

    Norman, Ryan B.; Gronoff, Guillaume; Mertens, Christopher J.

    2014-01-01

    Measuring the radiation environment at the surface of Mars is the primary goal of the Radiation Assessment Detector on the NASA Mars Science Laboratory's Curiosity rover. One of the conditions that Curiosity will likely encounter is a dust storm. The objective of this paper is to compute the cosmic ray ionization in different conditions, including dust storms, as these various conditions are likely to be encountered by Curiosity at some point. In the present work, the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety model, recently modified for Mars, was used along with the Badhwar & O'Neill 2010 galactic cosmic ray model. In addition to galactic cosmic rays, five different solar energetic particle event spectra were considered. For all input radiation environments, radiation dose throughout the atmosphere and at the surface was investigated as a function of atmospheric dust loading. It is demonstrated that for galactic cosmic rays, the ionization depends strongly on the atmosphere profile. Moreover, it is shown that solar energetic particle events strongly increase the ionization throughout the atmosphere, including ground level, and can account for the radio blackout conditions observed by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on the Mars Express spacecraft. These results demonstrate that the cosmic rays' influence on the Martian surface chemistry is strongly dependent on solar and atmospheric conditions that should be taken into account for future studies.

  15. Influence of dust loading on atmospheric ionizing radiation on Mars

    NASA Astrophysics Data System (ADS)

    Norman, Ryan B.; Gronoff, Guillaume; Mertens, Christopher J.

    2014-01-01

    Measuring the radiation environment at the surface of Mars is the primary goal of the Radiation Assessment Detector on the NASA Mars Science Laboratory's Curiosity rover. One of the conditions that Curiosity will likely encounter is a dust storm. The objective of this paper is to compute the cosmic ray ionization in different conditions, including dust storms, as these various conditions are likely to be encountered by Curiosity at some point. In the present work, the Nowcast of Atmospheric Ionizing Radiation for Aviation Safety model, recently modified for Mars, was used along with the Badhwar & O'Neill 2010 galactic cosmic ray model. In addition to galactic cosmic rays, five different solar energetic particle event spectra were considered. For all input radiation environments, radiation dose throughout the atmosphere and at the surface was investigated as a function of atmospheric dust loading. It is demonstrated that for galactic cosmic rays, the ionization depends strongly on the atmosphere profile. Moreover, it is shown that solar energetic particle events strongly increase the ionization throughout the atmosphere, including ground level, and can account for the radio blackout conditions observed by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument on the Mars Express spacecraft. These results demonstrate that the cosmic rays' influence on the Martian surface chemistry is strongly dependent on solar and atmospheric conditions that should be taken into account for future studies.

  16. Induction of thyroid cancer by ionizing radiation

    SciTech Connect

    Not Available

    1985-01-01

    This report assesses the potential for cancer induction in the thyroid gland after exposure of the gland to external x radiation and gamma radiation and/or some internally deposited radionuclides. Data and assumptions from existing human and animal studies are used to develop average risk estimates for populations over various ranges of radiation dose to the thyroid. The carcinogenicity of various iodine isotopes is examined. A specific model for risk estimation is developed which involves numerous modifications of an absolute risk model for factors such as age at exposure, sex, ethnic background, radiation source, exposure range, and time since exposure. Risk estimates are presented which are considered to be application to the population of the US for mean thyroidal doses in the range from 6 to 1500 rads. 146 references, 1 figures, 18 tables.

  17. Ionizing Radiation-induced Diseases in Korea

    PubMed Central

    Jeong, Meeseon; Moon, Kieun; Jo, Min-Heui; Kang, Seong-Kyu

    2010-01-01

    Radiation risk has become well known through epidemiological studies of clinically or occupationally exposed populations, animal experiments, and in vitro studies; however, the study of radiation related or induced disease has been limited in Korea. This study is to find the level of occupational radiation exposure for various kinds of accidents, compensated occupational diseases, related studies, and estimations on future occupational disease risks. Research data of related institutions were additionally investigated. About 67% of 62,553 radiation workers had no exposure or less than 1.2 mSv per year. The 5 reported cases on radiation accident patients in Korea occurred during nondestructive testing. According to the recent rapid increase in the number of workers exposed to radiation, a higher social recognition of cancer, and an increasing cancer mortality rate, it is expected that occupational disease compensation will rapidly increase as well. Therefore, it is important to develop scientific and objective decision methods, such as probability of causation and screening dose in the establishment of an exposure and health surveillance system. PMID:21258594

  18. Ionizing Radiation Impairs T Cell Activation by Affecting Metabolic Reprogramming

    PubMed Central

    Li, Heng-Hong; Wang, Yi-wen; Chen, Renxiang; Zhou, Bin; Ashwell, Jonathan D.; Fornace, Albert J.

    2015-01-01

    Ionizing radiation has a variety of acute and long-lasting adverse effects on the immune system. Whereas measureable effects of radiation on immune cell cytotoxicity and population change have been well studied in human and animal models, little is known about the functional alterations of the surviving immune cells after ionizing radiation. The objective of this study was to delineate the effects of radiation on T cell function by studying the alterations of T cell receptor activation and metabolic changes in activated T cells isolated from previously irradiated animals. Using a global metabolomics profiling approach, for the first time we demonstrate that ionizing radiation impairs metabolic reprogramming of T cell activation, which leads to substantial decreases in the efficiency of key metabolic processes required for activation, such as glucose uptake, glycolysis, and energy metabolism. In-depth understanding of how radiation impacts T cell function highlighting modulation of metabolism during activation is not only a novel approach to investigate the pivotal processes in the shift of T cell homeostasis after radiation, it also may lead to new targets for therapeutic manipulation in the combination of radiotherapy and immune therapy. Given that appreciable effects were observed with as low as 10 cGy, our results also have implications for low dose environmental exposures. PMID:26078715

  19. Combined effects of ionizing radiation and cycloheximide on gene expression

    SciTech Connect

    Woloschak, G.E.; Felcher, P.; Chang-Liu, Chin-Mei

    1993-11-01

    Experiments were done to determine the effects of ionizing radiation exposure on expression of genes following exposure of Syrian hamster embryo (SHE) cells to the protein synthesis inhibitor cycloheximide (including such genes as {beta}-actin, c-fos, H4-histone, c-myc, c-jun, Rb, and p53). Results revealed that when ionizing radiations (either fission-spectrum neutrons or {gamma}-rays) were administered 15 min following the cycloheximide treatment of SHE cells, the radiation exposure reduced cycloheximide-mediated gene induction for most of the induced genes studied (c-fos, H4-histone, c-jun) In addition, dose-rate differences were found when radiation exposure most significantly inhibited the cycloheximide response. Our results suggest (1) that ionizing radiation does not act as a general protein synthesis inhibitor and (2) that the presence of a labile (metastable) protein is required for the maintenance of transcription and mRNA accumulation following radiation exposure, especially for radiation administered at high dose-rates.

  20. Exploration of the Dissociative Recombination following DNA ionization to DNA+ due to ionizing radiation

    NASA Astrophysics Data System (ADS)

    Strom, Richard A.; Zimmerly, Andrew T.; Andrianarijaona, Vola M.

    2014-05-01

    It is known that ionizing radiation generates low-energy secondary electrons, which may interact with the surrounding area, including biomolecules, such as triggering DNA single strand and double strand breaks as demonstrated by Sanche and coworkers (Radiat. Res. 157, 227(2002)). The bio-effects of low-energy electrons are currently a topic of high interest. Most of the studies are dedicated to dissociative electron attachments; however, the area is still mostly unexplored and still not well understood. We are computationally investigating the effect of ionizing radiation on DNA, such as its ionization to DNA+. More specifically, we are exploring the possibility of the dissociative recombination of the temporary DNA+ with one of the low-energy secondary electrons, produced by the ionizing radiation, to be another process of DNA strand breaks. Our preliminary results, which are performed with the binaries of ORCA, will be presented. Authors wish to give special thanks to Pacific Union College Student Senate in Angwin, California, for their financial support.

  1. The oncogenic action of ionizing radiation on rat skin

    SciTech Connect

    Burns, F.J.

    1991-01-01

    Progress has occurred in several areas corresponding to the specific aims of the proposal: (1) Progression and multiple events in radiation carcinogenesis of rat skin as a function of LET; (2) cell cycle kinetics of irradiated rat epidermis as determined by double labeling and double emulsion autoradiography; (3) oncogene activation detected by in situ hybridization in radiation-induced rat skin tumors; (4) amplification of the c-myc oncogene in radiation-induced rat skin tumors as a function of LET; and (5) transformation of rat skin keratinocytes by ionizing radiation in combination with c-Ki-ras and c-myc oncogenes. 111 refs., 13 figs., 12 tabs.

  2. Effects of ionizing radiation in ginkgo and guarana [rapid communication

    NASA Astrophysics Data System (ADS)

    Rabelo Soriani, Renata; Cristina Satomi, Lucilia; Pinto, Terezinha de Jesus A.

    2005-07-01

    Raw plant materials normally carry high bioburden due to their origin, offering potential hazards to consumers. The use of decontamination processes is therefore an important step towards the consumer safety and therapeutical efficiency. Several authors have reported the treatment of medicinal herbs with ionizing radiation. This work evaluated the effects of different radiation doses on the microbial burden and chemical constituents of ginkgo ( Ginkgo biloba L.) and guaraná ( Paullinia cupana H.B.K.).

  3. Theoretical study of ionization radiation effects on optical fiber parameters

    NASA Astrophysics Data System (ADS)

    Poret, Jay C.; Suter, Joseph J.

    1994-06-01

    The effect of ionizing radiation on various fiber parameters has been examined. It was demonstrated that when the real refractive index increases, the V number increases as does the numerical aperture. The percentage of power propagating in the cladding decreases with increasing real refractive index. Small changes in the refractive index will induce additional modes to form. The effect of radiation on fiber dispersion was reasoned to be negligible for short lengths of fibers (< 2 km).

  4. Ionizing Radiation Environments and Exposure Risks

    NASA Astrophysics Data System (ADS)

    Kim, M. H. Y.

    2015-12-01

    Space radiation environments for historically large solar particle events (SPE) and galactic cosmic rays (GCR) are simulated to characterize exposures to radio-sensitive organs for missions to low-Earth orbit (LEO), moon, near-Earth asteroid, and Mars. Primary and secondary particles for SPE and GCR are transported through the respective atmospheres of Earth or Mars, space vehicle, and astronaut's body tissues using NASA's HZETRN/QMSFRG computer code. Space radiation protection methods, which are derived largely from ground-based methods recommended by the National Council on Radiation Protection and Measurements (NCRP) or International Commission on Radiological Protections (ICRP), are built on the principles of risk justification, limitation, and ALARA (as low as reasonably achievable). However, because of the large uncertainties in high charge and energy (HZE) particle radiobiology and the small population of space crews, NASA develops distinct methods to implement a space radiation protection program. For the fatal cancer risks, which have been considered the dominant risk for GCR, the NASA Space Cancer Risk (NSCR) model has been developed from recommendations by NCRP; and undergone external review by the National Research Council (NRC), NCRP, and through peer-review publications. The NSCR model uses GCR environmental models, particle transport codes describing the GCR modification by atomic and nuclear interactions in atmospheric shielding coupled with spacecraft and tissue shielding, and NASA-defined quality factors for solid cancer and leukemia risk estimates for HZE particles. By implementing the NSCR model, the exposure risks from various heliospheric conditions are assessed for the radiation environments for various-class mission types to understand architectures and strategies of human exploration missions and ultimately to contribute to the optimization of radiation safety and well-being of space crewmembers participating in long-term space missions.

  5. The effects of ionizing radiation on avian erythrocytes

    SciTech Connect

    Lee, S.W.; Ducoff, H.S.

    1994-01-01

    The effects of ionizing radiation were examined in terminally differentiated cells using nucleated chicken erythrocytes (RBCs) as the model. We used a hemolytic assay to score radiation damage to RBCs. Chicken RBCs received 0 to 100 Gy of radiation at dose rate of 10 Gy/min. Radiation-induced hemolysis occurred in a dose-dependent manner but not immediately after irradiation. Hemolysis became apparent at 24 h after treatment. A threshold for radiation dose response was observed. At doses below 30 Gy, hemolysis in irradiated samples was indistinguishable from that in nonirradiated controls. A total dose of 100 Gy was used for the split-dose experiments. The results showed that chicken RBCs were able to repair radiation damage and that the half-time for maximum recovery was approximately 30 min at 36{degrees}C. Recovery from {gamma} radiation was also affected by the interfraction temperature. 36 refs., 7 figs.

  6. Effects of ionizing radiation on charge-coupled imagers

    NASA Technical Reports Server (NTRS)

    Killiany, J. M.; Baker, W. D.; Saks, N. S.; Barbe, D. F.

    1975-01-01

    The effects of ionizing radiation on three different charge coupled imagers have been investigated. Device performance was evaluated as a function of total gamma ray dose. The principal failure mechanisms have been identified for each particular device structure. The clock and bias voltages required for high total dose operation of the devices are presented.

  7. Future directions for LDEF ionizing radiation modeling and assessments

    NASA Technical Reports Server (NTRS)

    Armstrong, T. W.; Colborn, B. L.

    1992-01-01

    Data from the ionizing radiation dosimetry aboard LDEF provide a unique opportunity for assessing the accuracy of current space radiation models and in identifying needed improvements for future mission applications. Details are given of the LDEF data available for radiation model evaluations. The status is given of model comparisons with LDEF data, along with future directions of planned modeling efforts and data comparison assessments. The methodology is outlined which is related to modeling being used to help insure that the LDEF ionizing radiation results can be used to address ionizing radiation issues for future missions. In general, the LDEF radiation modeling has emphasized quick-look predictions using simplified methods to make comparisons with absorbed dose measurements and induced radioactivity measurements of emissions. Modeling and LDEF data comparisons related to linear energy transfer spectra are of importance for several reasons which are outlined. The planned modeling and LDEF data comparisons for LET spectra is discussed, including components of the LET spectra due to different environment sources, contribution from different production mechanisms, and spectra in plastic detectors vs silicon.

  8. Ionizing radiation delivered by specific antibody is therapeutic against a fungal infection

    NASA Astrophysics Data System (ADS)

    Dadachova, Ekaterina; Nakouzi, Antonio; Bryan, Ruth A.; Casadevall, Arturo

    2003-09-01

    There is an urgent need for new antimicrobial therapies to combat drug resistance, new pathogens, and the relative inefficacy of current therapy in compromised hosts. Ionizing radiation can kill microorganisms quickly and efficiently, but this modality has not been exploited as a therapeutic antimicrobial strategy. We have developed methods to target ionizing radiation to a fungal cell by labeling a specific mAb with the therapeutic radioisotopes Rhenium-188 and Bismuth-213. Radiolabeled antibody killed cells of human pathogenic fungus Cryptococcus neoformans in vitro, thus converting an antibody with no inherent antifungal activity into a microbicidal molecule. Administration of radiolabeled antibody to mice with C. neoformans infection delivered 213Bi and 188Re to the sites of infection, reduced their organ fungal burden, and significantly prolonged their survival without apparent toxicity. This study establishes the principle that targeted radiation can be used for the therapy of an infectious disease, and suggests that it may have wide applicability as an antimicrobial strategy.

  9. Isolation and characterization of BHK cells sensitive to ionizing radiation and alkylating agents

    SciTech Connect

    Evans, H.H.; Horng, M.F.; Weber, M.C.; Glazier, K.G.

    1984-07-01

    A host-cell viral suicide enrichment procedure was used to isolate BHK strains sensitive to ionizing radiation. Of six strains surviving infection with irradiated herpes simplex virus (HSV), three were found to be more sensitive to ionizing radiation than the parental BHK cells. Strains V1 and V2 were studied in more detail and found to exhibit hypersensitivity to ethyl methanesulfonate (EMS), methyl methanesulfonate, and N-methyl-N'-nitro-N-nitrosoguanidine, but not to uv radiation. Susceptibility to mutation in response to EMS was also compared in BHK and strains V1 and V2. The frequency of induction of ouabain-resistant cells was 140% of the parental strain in the case of strain V1 and 58% of the parental strain in the case of strain V2.

  10. Methylation of the ATM promoter in glioma cells alters ionizing radiation sensitivity

    SciTech Connect

    Roy, Kanaklata; Wang, Lilin; Makrigiorgos, G. Mike; Price, Brendan D. . E-mail: brendan_price@dfci.harvard.edu

    2006-06-09

    Glioblastomas are among the malignancies most resistant to radiation therapy. In contrast, cells lacking the ATM protein are highly sensitive to ionizing radiation. The relationship between ATM protein expression and radiosensitivity in 3 glioma cell lines was examined. T98G cells exhibited normal levels of ATM protein, whereas U118 and U87 cells had significantly lower levels of ATM and increased (>2-fold) sensitivity to ionizing radiation compared to T98G cells. The ATM promoter was methylated in U87 cells. Demethylation by azacytidine treatment increased ATM protein levels in the U87 cells and decreased their radiosensitivity. In contrast, the ATM promoter in U118 cells was not methylated. Further, expression of exogenous ATM did not significantly alter the radiosensitivity of U118 cells. ATM expression is therefore heterogeneous in the glioma cells examined. In conclusion, methylation of the ATM promoter may account for the variable radiosensitivity and heterogeneous ATM expression in a fraction of glioma cells.

  11. Reducing ionizing radiation doses during cardiac interventions in pregnant women

    PubMed Central

    Orchard, Elizabeth; Dix, Sarah; Wilson, Neil; Mackillop, Lucy; Ormerod, Oliver

    2012-01-01

    Background There is concern over ionizing radiation exposure in women who are pregnant or of child-bearing age. Due to the increasing prevalence of congenital and acquired heart disease, the number of women who require cardiac interventions during pregnancy has increased. We have developed protocols for cardiac interventions in pregnant women and women of child-bearing age, aimed at substantially reducing both fluoroscopy duration and radiation doses. Methods Over five years, we performed cardiac interventions on 15 pregnant women, nine postpartum women and four as part of prepregnancy assessment. Fluoroscopy times were minimized by simultaneous use of intracardiac echocardiography, and by using very low frame rates (2/second) during fluoroscopy. Results The procedures most commonly undertaken were closure of atrial septal defect (ASD) or patent foramen ovale (PFO) in 16 women, coronary angiograms in seven, right and left heart catheters in three and two stent placements. The mean screening time for all patients was 2.38 minutes (range 0.48–13.7), the median radiation dose was 66 (8.9–1501) Gy/cm2. The median radiation dose to uterus was 1.92 (0.59–5.47) μGy, and the patient estimated dose was 0.24 (0.095–0.80) mSv. Conclusions Ionizing radiation can be used safely in the management of severe cardiac structural disease in pregnancy, with very low ionizing radiation dose to the mother and extremely low exposure to the fetus. With experience, ionizing radiation doses at our institution have been reduced.

  12. Studying the Effect of Ionization Radiation of 60Co on the Spirulina

    NASA Astrophysics Data System (ADS)

    Ai, Weidang; Guo, Shuang-Sheng; Ai, Weidang; Dong, Wen-Ping; Qin, Li-Feng; Tang, Yong-Kang

    It studied the effect of ionization radiation on the Spirulina plastensis(No.6) by using the γ-rays of 60 Co. In the experiment, Spirulina were irradiated, and the dose of the ionization radiation covered 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0kGy. After irradiating, these Spirulina were cultured under the same conditions. During the course of the experiment, the growth rate, photosynthetic efficiency and nutrition quality of the Spirulina, were analyzed. From the results, low dose of γ-rays (less than 1.5kGy) could improve the content of phycobilin and protein of Spirulina. Only small changes in the morphology of algae filament were found at dose less than 1.0kGy. But with the increase of the dose of γ-rays (more than 1.5kGy), the filaments would break up or even disintegrate. Spirulina had stronger ionization radiation proof and self-rehabilitation capacity, but the growth of Spirulina was stagnated. The LD50 (i.e. the dose resulted in 50% death of the Spirulina) of the colony was 2.0kGy. Considering the capacity of being resistant to γ-rays irradiation, Spirulina can be considered as one of the key biological components in the Controlled Ecological Life Support System (CELSS) for future long-term space missions. Keywords: Controlled Ecological Life Support System (CELSS); Spirulina; ionization radiation; biological component

  13. Rays Sting: The Acute Cellular Effects of Ionizing Radiation Exposure.

    PubMed

    Franco, A; Ciccarelli, M; Sorriento, D; Napolitano, L; Fiordelisi, A; Trimarco, B; Durante, M; Iaccarino, G

    2016-05-01

    High-precision radiation therapy is a clinical approach that uses the targeted delivery of ionizing radiation, and the subsequent formation of reactive oxygen species (ROS) in high proliferative, radiation sensitive cancers. In particular, in thoracic cancer ratdiation treatments, can not avoid a certain amount of cardiac toxicity. Given the low proliferative rate of cardiac myocytes, research has looked at the effect of radiation on endothelial cells and consequent coronary heart disease as the mechanism of ratdiation induced cardiotoxicity. In fact, little is known concerning the direct effect of radiation on mitochondria dynamis in cardiomyocyte. The main effect of ionizing radiation is the production of ROS and recent works have uncovered that they directly participates to pivotal cell function like mitochondrial quality control. In particular ROS seems to act as check point within the cell to promote either mitochondrial biogenesis and survival or mitochondrial damage and apoptosis. Thus, it appears evident that the functional state of the cell, as well as the expression patterns of molecules involved in mitochondrial metabolism may differently modulate mitochondrial fate in response to radiation induced ROS responses. Different molecules have been described to localize to mitochondria and regulate ROS production in response to stress, in particular GRK2. In this review we will discuss the evidences on the cardiac toxicity induced by X ray radiation on cardiomyocytes with emphasis on the role played by mitochondria dynamism. PMID:27326395

  14. Rays Sting: The Acute Cellular Effects of Ionizing Radiation Exposure

    PubMed Central

    Franco, A; Ciccarelli, M; Sorriento, D; Napolitano, L; Fiordelisi, A; Trimarco, B; Durante, M; Iaccarino, G

    2016-01-01

    High-precision radiation therapy is a clinical approach that uses the targeted delivery of ionizing radiation, and the subsequent formation of reactive oxygen species (ROS) in high proliferative, radiation sensitive cancers. In particular, in thoracic cancer ratdiation treatments, can not avoid a certain amount of cardiac toxicity. Given the low proliferative rate of cardiac myocytes, research has looked at the effect of radiation on endothelial cells and consequent coronary heart disease as the mechanism of ratdiation induced cardiotoxicity. In fact, little is known concerning the direct effect of radiation on mitochondria dynamis in cardiomyocyte. The main effect of ionizing radiation is the production of ROS and recent works have uncovered that they directly participates to pivotal cell function like mitochondrial quality control. In particular ROS seems to act as check point within the cell to promote either mitochondrial biogenesis and survival or mitochondrial damage and apoptosis. Thus, it appears evident that the functional state of the cell, as well as the expression patterns of molecules involved in mitochondrial metabolism may differently modulate mitochondrial fate in response to radiation induced ROS responses. Different molecules have been described to localize to mitochondria and regulate ROS production in response to stress, in particular GRK2. In this review we will discuss the evidences on the cardiac toxicity induced by X ray radiation on cardiomyocytes with emphasis on the role played by mitochondria dynamism. PMID:27326395

  15. Metabolic phenotyping reveals a lipid mediator response to ionizing radiation.

    PubMed

    Laiakis, Evagelia C; Strassburg, Katrin; Bogumil, Ralf; Lai, Steven; Vreeken, Rob J; Hankemeier, Thomas; Langridge, James; Plumb, Robert S; Fornace, Albert J; Astarita, Giuseppe

    2014-09-01

    Exposure to ionizing radiation has dramatically increased in modern society, raising serious health concerns. The molecular response to ionizing radiation, however, is still not completely understood. Here, we screened mouse serum for metabolic alterations following an acute exposure to γ radiation using a multiplatform mass-spectrometry-based strategy. A global, molecular profiling revealed that mouse serum undergoes a series of significant molecular alterations following radiation exposure. We identified and quantified bioactive metabolites belonging to key biochemical pathways and low-abundance, oxygenated, polyunsaturated fatty acids (PUFAs) in the two groups of animals. Exposure to γ radiation induced a significant increase in the serum levels of ether phosphatidylcholines (PCs) while decreasing the levels of diacyl PCs carrying PUFAs. In exposed mice, levels of pro-inflammatory, oxygenated metabolites of arachidonic acid increased, whereas levels of anti-inflammatory metabolites of omega-3 PUFAs decreased. Our results indicate a specific serum lipidomic biosignature that could be utilized as an indicator of radiation exposure and as novel target for therapeutic intervention. Monitoring such a molecular response to radiation exposure might have implications not only for radiation pathology but also for countermeasures and personalized medicine. PMID:25126707

  16. Hydraulic effects in a radiative atmosphere with ionization

    NASA Astrophysics Data System (ADS)

    Bhat, P.; Brandenburg, A.

    2016-03-01

    Context. In his 1978 paper, Eugene Parker postulated the need for hydraulic downward motion to explain magnetic flux concentrations at the solar surface. A similar process has also recently been seen in simplified (e.g., isothermal) models of flux concentrations from the negative effective magnetic pressure instability (NEMPI). Aims: We study the effects of partial ionization near the radiative surface on the formation of these magnetic flux concentrations. Methods: We first obtain one-dimensional (1D) equilibrium solutions using either a Kramers-like opacity or the H- opacity. The resulting atmospheres are then used as initial conditions in two-dimensional (2D) models where flows are driven by an imposed gradient force that resembles a localized negative pressure in the form of a blob. To isolate the effects of partial ionization and radiation, we ignore turbulence and convection. Results: Because of partial ionization, an unstable stratification always forms near the surface. We show that the extrema in the specific entropy profiles correspond to the extrema in the degree of ionization. In the 2D models without partial ionization, strong flux concentrations form just above the height where the blob is placed. Interestingly, in models with partial ionization, such flux concentrations always form at the surface well above the blob. This is due to the corresponding negative gradient in specific entropy. Owing to the absence of turbulence, the downflows reach transonic speeds. Conclusions: We demonstrate that, together with density stratification, the imposed source of negative pressure drives the formation of flux concentrations. We find that the inclusion of partial ionization affects the entropy profile dramatically, causing strong flux concentrations to form closer to the surface. We speculate that turbulence effects are needed to limit the strength of flux concentrations and homogenize the specific entropy to a stratification that is close to marginal.

  17. ADVISORY ON UPDATED METHODOLOGY FOR ESTIMATING CANCER RISKS FROM EXPOSURE TO IONIZING RADIATION

    EPA Science Inventory

    The National Academy of Sciences (NAS) published the Biological Effects of Ionizing Radiation (BEIR) committee's report (BEIR VII) on risks from ionizing radiation exposures in 2006. The Committee analyzed the most recent epidemiology from the important exposed cohorts and factor...

  18. Atmospheric Ionizing Radiation (AIR) ER-2 Preflight Analysis

    NASA Technical Reports Server (NTRS)

    Tai, Hsiang; Wilson, John W.; Maiden, D. L.

    1998-01-01

    Atmospheric ionizing radiation (AIR) produces chemically active radicals in biological tissues that alter the cell function or result in cell death. The AIR ER-2 flight measurements will enable scientists to study the radiation risk associated with the high-altitude operation of a commercial supersonic transport. The ER-2 radiation measurement flights will follow predetermined, carefully chosen courses to provide an appropriate database matrix which will enable the evaluation of predictive modeling techniques. Explicit scientific results such as dose rate, dose equivalent rate, magnetic cutoff, neutron flux, and air ionization rate associated with those flights are predicted by using the AIR model. Through these flight experiments, we will further increase our knowledge and understanding of the AIR environment and our ability to assess the risk from the associated hazard.

  19. Effects of diagnostic ionizing radiation on pregnancy via TEM

    NASA Astrophysics Data System (ADS)

    Mohammed, W. H.; Artoli, A. M.

    2008-08-01

    In Sudan, X-rays are routinely used at least once for measurements of pelvis during the gestation period, though this is highly prohibited worldwide, except for a few life threatening cases. To demonstrate the effect of diagnostic ionizing radiation on uterus, fetus and neighboring tissues to the ovaries, two independent experiments on pregnant rabbits were conducted. The first experiment was a proof of concept that diagnostic ionizing radiation is hazardous throughout the gestation period. The second experiment was done through Transmission Electron Microscopy (TEM) to elucidate the morphological changes in the ultra structure of samples taken from irradiated pregnant rabbits. This study uses TEM to test the effect of diagnostic radiation of less than 0.6 Gray on the cellular level. Morphological changes have been captured and the images were analyzed to quantify these effects.

  20. [Risks associated to ionizing radiation from natural sources].

    PubMed

    Laurier, Dominique; Gay, Didier

    2015-01-01

    This article presents an overview of current knowledge about natural sources of radiation exposure and potential associated health risks. Natural radioactivity constitutes the main source of exposure to ionizing radiation of the French and world population. Exposure is both external (telluric and cosmic rays) and internal (radon inhalation and ingestion of radionuclides from food and drinking water). It varies according to altitude, geology, and individual way of life (housing, food habits). Epidemiological studies demonstrated an excess risk of lung cancer associated to domestic radon exposure, ranking radon at the second place of known lung cancer risk factors after smoking. Data currently available do not allow concluding to risks associated to other natural sources of exposure to ionizing radiation. PMID:25842437

  1. Ionizing radiation-induced mutagenesis: radiation studies in Neurospora predictive for results in mammalian cells

    NASA Technical Reports Server (NTRS)

    Evans, H. H.; DeMarini, D. M.

    1999-01-01

    Ionizing radiation was the first mutagen discovered and was used to develop the first mutagenicity assay. In the ensuing 70+ years, ionizing radiation became a fundamental tool in understanding mutagenesis and is still a subject of intensive research. Frederick de Serres et al. developed and used the Neurospora crassa ad-3 system initially to explore the mutagenic effects of ionizing radiation. Using this system, de Serres et al. demonstrated the dependence of the frequency and spectra of mutations induced by ionizing radiation on the dose, dose rate, radiation quality, repair capabilities of the cells, and the target gene employed. This work in Neurospora predicted the subsequent observations of the mutagenic effects of ionizing radiation in mammalian cells. Modeled originally on the mouse specific-locus system developed by William L. Russell, the N. crassa ad-3 system developed by de Serres has itself served as a model for interpreting the results in subsequent systems in mammalian cells. This review describes the primary findings on the nature of ionizing radiation-induced mutagenesis in the N. crassa ad-3 system and the parallel observations made years later in mammalian cells.

  2. Radiation hydrodynamical instabilities in cosmological and galactic ionization fronts

    NASA Astrophysics Data System (ADS)

    Whalen, Daniel J.; Norman, Michael L.

    2011-11-01

    Ionization fronts, the sharp radiation fronts behind which H/He ionizing photons from massive stars and galaxies propagate through space, were ubiquitous in the universe from its earliest times. The cosmic dark ages ended with the formation of the first primeval stars and galaxies a few hundred Myr after the Big Bang. Numerical simulations suggest that stars in this era were very massive, 25-500 solar masses, with H(II) regions of up to 30,000 light-years in diameter. We present three-dimensional radiation hydrodynamical calculations that reveal that the I-fronts of the first stars and galaxies were prone to violent instabilities, enhancing the escape of UV photons into the early intergalactic medium (IGM) and forming clumpy media in which supernovae later exploded. The enrichment of such clumps with metals by the first supernovae may have led to the prompt formation of a second generation of low-mass stars, profoundly transforming the nature of the first protogalaxies. Cosmological radiation hydrodynamics is unique because ionizing photons coupled strongly to both gas flows and primordial chemistry at early epochs, introducing a hierarchy of disparate characteristic timescales whose relative magnitudes can vary greatly throughout a given calculation. We describe the adaptive multistep integration scheme we have developed for the self-consistent transport of both cosmological and galactic ionization fronts.

  3. Detecting ionizing radiation with optical fibers down to biomedical doses

    NASA Astrophysics Data System (ADS)

    Avino, S.; D'Avino, V.; Giorgini, A.; Pacelli, R.; Liuzzi, R.; Cella, L.; De Natale, P.; Gagliardi, G.

    2013-10-01

    We report on a passive ionizing radiation sensor based on a fiber-optic resonant cavity interrogated by a high resolution interferometric technique. After irradiation in clinical linear accelerators, we observe significant variations of the fiber thermo-optic coefficient. Exploiting this effect, we demonstrate an ultimate detection limit of 160 mGy with an interaction volume of only 6 × 10-4 mm3. Thanks to its reliability, compactness, and sensitivity at biomedical dose levels, our system lends itself to real applications in radiation therapy procedures as well as in radiation monitoring and protection in medicine, aerospace, and nuclear power plants.

  4. Melatonin protection from chronic, low-level ionizing radiation.

    PubMed

    Reiter, Russel J; Korkmaz, Ahmet; Ma, Shuran; Rosales-Corral, Sergio; Tan, Dun-Xian

    2011-12-15

    In the current survey, we summarize the published literature which supports the use of melatonin, an endogenously produced molecule, as a protective agent against chronic, low-level ionizing radiation. Under in vitro conditions, melatonin uniformly was found to protect cellular DNA and plasmid super coiled DNA from ionizing radiation damage due to Cs(137) or X-radiation exposure. Likewise, in an in vivo/in vitro study in which humans were given melatonin orally and then their blood lymphocytes were collected and exposed to Cs(137) ionizing radiation, nuclear DNA from the cells of those individuals who consumed melatonin (and had elevated blood levels) was less damaged than that from control individuals. In in vivo studies as well, melatonin given to animals prevented DNA and lipid damage (including limiting membrane rigidity) and reduced the percentage of animals that died when they had been exposed to Cs(137) or Co(60) radiation. Melatonin's ability to protect macromolecules from the damage inflicted by ionizing radiation likely stems from its high efficacy as a direct free radical scavenger and possibly also due to its ability to stimulate antioxidative enzymes. Melatonin is readily absorbed when taken orally or via any other route. Melatonin's ease of self administration and its virtual absence of toxicity or side effects, even when consumed over very long periods of time, are essential when large populations are exposed to lingering radioactive contamination such as occurs as a result of an inadvertent nuclear accident, an intentional nuclear explosion or the detonation of a radiological dispersion device, i.e., a "dirty" bomb. PMID:22185900

  5. Radioprotective properties of tocopherol succinate against ionizing radiation in mice

    PubMed Central

    Singh, Vijay K.; Singh, Pankaj K.; Wise, Stephen Y.; Posarac, Ana; Fatanmi, Oluseyi O.

    2013-01-01

    Threats of nuclear and other radiologic exposures have been increasing but no countermeasure for acute radiation syndrome has been approved by regulatory authorities. In prior publications we have demonstrated the efficacy of tocopherol succinate (TS) as a promising radiation countermeasure with the potential to protect against lethal doses of ionizing radiation exposure. The aim of this study was to gain further insight regarding how TS protects mice against a lethal dose of radiation. CD2F1 mice were injected subcutaneously with 400 mg/kg of TS, and 24 h later exposed to 60Co γ–radiation. Intestinal tissues or spleen/thymus were harvested after irradiation and analyzed for CD68-positive inflammatory cells and apoptotic cells by immunostaining of jejunal cross-sections. Comet assay was used to analyze DNA damage in various tissues. Phospho-histone H3(pH3) and the proliferating cell nuclear antigen (PCNA) were used as mitotic markers for immunostaining jejunal cross-sections. We observed that injecting TS significantly decreased the number of CD68-positive cells, DNA damage and apoptotic cells (BAX, caspase 3 and cleaved poly(ADP-ribose) polymerase-positive cells) as judged by various apoptotic pathway markers. TS treatment also increased proliferating cells in irradiated mice. Results of this study further support our contention that TS protects mice against lethal doses of ionizing radiation by inhibiting radiation-induced apoptosis and DNA damage while enhancing cell proliferation. PMID:23038797

  6. Hybrid hydrogels produced by ionizing radiation technique

    NASA Astrophysics Data System (ADS)

    Oliveira, M. J. A.; Amato, V. S.; Lugão, A. B.; Parra, D. F.

    2012-09-01

    The interest in biocompatible hydrogels with particular properties has increased considerably in recent years due to their versatile applications in biomedicine, biotechnology, pharmacy, agriculture and controlled release of drugs. The use of hydrogels matrices for particular drug-release applications has been investigated with the synthesis of modified polymeric hydrogel of PVAl and 0.5, 1.0, 1.5% nano-clay. They were processed using gamma radiation from Cobalt-60 source at 25 kGy dose. The characterization of the hydrogels was conducted and toxicity was evaluated. The dried hydrogel was analyzed for thermogravimetry analysis (TGA), infrared spectroscopy (FTIR) and swelling in solutions of different pH. The membranes have no toxicity. The nano-clay influences directly the equilibrium swelling.

  7. Ionizing radiation and aging: rejuvenating an old idea

    PubMed Central

    Richardson, Richard B.

    2009-01-01

    This paper reviews the contemporary evidence that radiation can accelerate aging, degenerative health effects and mortality. Around the 1960s, the idea that ionizing radiation caused premature aging was dismissed as the radiation-induced health effects appeared to be virtually confined to neoplasms. More recently, radiation has become associated with a much wider spectrum of age-related diseases, including cardiovascular disease; although some diseases of old age, such as diabetes, are notably absent as a radiation risk. On the basis of recent research, is there a stronger case today to be made linking radiation and aging? Comparison is made between the now-known biological mechanisms of aging and those of radiation, including oxidative stress, chromosomal damage, apoptosis, stem cell exhaustion and inflammation. The association between radiation effects and the free-radical theory of aging as the causative hypothesis seems to be more compelling than that between radiation and the nutrient-sensing TOR pathway. Premature aging has been assessed by biomarkers in calorie restriction studies; yet, biomarkers such as telomere erosion and p16INK4a are ambiguous for radiation-induced aging. Some animal studies suggest low dose radiation may even demonstrate hormesis health benefits. Regardless, there is virtually no support for a life span extending hypothesis for A-bomb survivors and other exposed subjects. PMID:20157573

  8. Transcriptional profile of immediate response to ionizing radiation exposure.

    PubMed

    Rouchka, Eric C; Flight, Robert M; Fasciotto, Brigitte H; Estrada, Rosendo; Eaton, John W; Patibandla, Phani K; Waigel, Sabine J; Li, Dazhuo; Kirtley, John K; Sethu, Palaniappan; Keynton, Robert S

    2016-03-01

    Astronauts participating in long duration space missions are likely to be exposed to ionizing radiation associated with highly energetic and charged heavy particles. Previously proposed gene biomarkers for radiation exposure include phosphorylated H2A Histone Family, Member X (γH2AX), Tumor Protein 53 (TP53), and Cyclin-Dependent Kinase Inhibitor 1A (CDKN1A). However, transcripts of these genes may not be the most suitable biomarkers for radiation exposure due to a lack of sensitivity or specificity. As part of a larger effort to develop lab-on-a-chip methods for detecting radiation exposure events using blood samples, we designed a dose-course microarray study in order to determine coding and non-coding RNA transcripts undergoing differential expression immediately following radiation exposure. The main goal was to elicit a small set of sensitive and specific radiation exposure biomarkers at low, medium, and high levels of ionizing radiation exposure. Four separate levels of radiation were considered: 0 Gray (Gy) control; 0.3 Gy; 1.5 Gy; and 3.0 Gy with four replicates at each radiation level. This report includes raw gene expression data files from the resulting microarray experiments from all three radiation levels ranging from a lower, typical exposure than an astronaut might see (0.3 Gy) to high, potentially lethal, levels of radiation (3.0 Gy). The data described here is available in NCBI's Gene Expression Omnibus (GEO), accession GSE64375. PMID:26981369

  9. Transcriptional profile of immediate response to ionizing radiation exposure

    PubMed Central

    Rouchka, Eric C.; Flight, Robert M.; Fasciotto, Brigitte H.; Estrada, Rosendo; Eaton, John W.; Patibandla, Phani K.; Waigel, Sabine J.; Li, Dazhuo; Kirtley, John K.; Sethu, Palaniappan; Keynton, Robert S.

    2015-01-01

    Astronauts participating in long duration space missions are likely to be exposed to ionizing radiation associated with highly energetic and charged heavy particles. Previously proposed gene biomarkers for radiation exposure include phosphorylated H2A Histone Family, Member X (γH2AX), Tumor Protein 53 (TP53), and Cyclin-Dependent Kinase Inhibitor 1A (CDKN1A). However, transcripts of these genes may not be the most suitable biomarkers for radiation exposure due to a lack of sensitivity or specificity. As part of a larger effort to develop lab-on-a-chip methods for detecting radiation exposure events using blood samples, we designed a dose–course microarray study in order to determine coding and non-coding RNA transcripts undergoing differential expression immediately following radiation exposure. The main goal was to elicit a small set of sensitive and specific radiation exposure biomarkers at low, medium, and high levels of ionizing radiation exposure. Four separate levels of radiation were considered: 0 Gray (Gy) control; 0.3 Gy; 1.5 Gy; and 3.0 Gy with four replicates at each radiation level. This report includes raw gene expression data files from the resulting microarray experiments from all three radiation levels ranging from a lower, typical exposure than an astronaut might see (0.3 Gy) to high, potentially lethal, levels of radiation (3.0 Gy). The data described here is available in NCBI's Gene Expression Omnibus (GEO), accession GSE64375. PMID:26981369

  10. Effects of ionizing radiation on cryogenic infrared detectors

    NASA Technical Reports Server (NTRS)

    Moseley, S. H.; Silverberg, R. F.; Lakew, B.

    1989-01-01

    The Diffuse Infrared Background Experiment (DIRBE) is one of three experiments to be carried aboard the Cosmic Background Explorer (COBE) satellite scheduled to be launched by NASA on a Delta rocket in 1989. The DIRBE is a cryogenic absolute photometer operating in a liquid helium dewar at 1.5 K. Photometric stability is a principal requirement for achieving the scientific objectives of this experiment. The Infrared Astronomy Satellite (IRAS), launched in 1983, which used detectors similar to those in DIRBE, revealed substantial changes in detector responsivity following exposure to ionizing radiation encountered on passage through the South Atlantic Anomaly (SAA). Since the COBE will use the same 900 Km sun-synchronous orbit as IRAS, ionizing radiation-induced performance changes in the detectors were a major concern. Here, ionizing radiation tests carried out on all the DIRBE photodetectors are reported. Responsivity changes following exposure to gamma rays, protons, and alpha particle are discussed. The detector performance was monitored following a simulated entire mission life dose. In addition, the response of the detectors to individual particle interactions was measured. The InSb photovoltaic detectors and the Blocked Impurity Band (BIB) detectors revealed no significant change in responsivity following radiation exposure. The Ge:Ga detectors show large effects which were greatly reduced by proper thermal annealing.

  11. Effects of ionizing radiation on cryogenic infrared detectors

    NASA Astrophysics Data System (ADS)

    Moseley, S. H.; Silverberg, R. F.; Lakew, B.

    The Diffuse Infrared Background Experiment (DIRBE) is one of three experiments to be carried aboard the Cosmic Background Explorer (COBE) satellite scheduled to be launched by NASA on a Delta rocket in 1989. The DIRBE is a cryogenic absolute photometer operating in a liquid helium dewar at 1.5 K. Photometric stability is a principal requirement for achieving the scientific objectives of this experiment. The Infrared Astronomy Satellite (IRAS), launched in 1983, which used detectors similar to those in DIRBE, revealed substantial changes in detector responsivity following exposure to ionizing radiation encountered on passage through the South Atlantic Anomaly (SAA). Since the COBE will use the same 900 Km sun-synchronous orbit as IRAS, ionizing radiation-induced performance changes in the detectors were a major concern. Here, ionizing radiation tests carried out on all the DIRBE photodetectors are reported. Responsivity changes following exposure to gamma rays, protons, and alpha particle are discussed. The detector performance was monitored following a simulated entire mission life dose. In addition, the response of the detectors to individual particle interactions was measured. The InSb photovoltaic detectors and the Blocked Impurity Band (BIB) detectors revealed no significant change in responsivity following radiation exposure. The Ge:Ga detectors show large effects which were greatly reduced by proper thermal annealing.

  12. Effects Of Ionizing Radiation On Cryogenic Infrared Detectors

    NASA Astrophysics Data System (ADS)

    Moseley, S. H.; Lakew, B.; Silverberg, R. F.

    1988-04-01

    The Diffuse Infrared Background Experiment (DIRBE) is one of three experiments to be carried aboard the Cosmic Background Explorer (COBE) satellite scheduled to be launched by NASA on a Delta rocket in 1989. The DIRBE is a cryogenic absolute photometer operating in a liquid helium dewar at 1.5K. Photometric stability is a principal requirement for achieving the scientific objectives of this experiment. The Infrared Astronomy Satellite (IRAS), launched in 1983, which used detectors similar to those in DIRBE, revealed substantial changes in detector responsivity following exposure to ionizing radiation encountered on passage through the South Atlantic Anomaly (SAA). Since the COBE will use the same 900 Km sun-synchronous orbit as IRAS, ionizing radiation-induced performance changes in the detectors were a major concern. We report here on ionizing radiation tests carried out on all the DIRBE photodetectors. Responsivity changes following exposure to gamma rays, protons, and alpha particle are discussed. The detector performance was monitored following a simulated entire mission life dose. In addition, the response of the detectors to individual particle interactions was measured. The InSb photovoltaic detectors and the Blocked Impurity Band (BIB) detectors revealed no significant change in responsivity following radiation exposure. The Ge:Ga detectors show large effects which were greatly reduced by proper thermal annealing.

  13. Neoplastic transformation of immortalized human epidermal keratinocytes by ionizing radiation

    SciTech Connect

    Thraves, P.; Salehi, Z.; Dritschilo, A.; Rhim, J.S. )

    1990-02-01

    Efforts to investigate the progression of events that cause human cells to become neoplastic in response to ionizing radiation have been aided by the development of tissue culture systems of epithelial cells. In the present study, nontumorigenic human epidermal keratinocytes immortalized by adenovirus type 12 and simian virus 40 have been transformed by exposure to x-ray irradiation. Such transformants showed morphological alterations, formed colonies in soft agar, and induced carcinomas when transplanted into nude mice, whereas primary human epidermal keratinocytes exposed to radiation in this manner failed to show any evidence of transformation. These findings demonstrate the malignant transformation of human primary epithelial cells in culture by the combined action of a DNA tumor virus and radiation, indicating a multistep process for radiation-induced neoplastic conversion. This in vitro system may be useful as a tool for dissecting the process of radiation-induced neoplastic transformation of human epithelial cells and for detecting previously unreported human oncogenes.

  14. The ionizing radiation environment of LDEF prerecovery predictions

    NASA Technical Reports Server (NTRS)

    Watts, John W., Jr.; Derrickson, James H.; Parnell, T. A.; Fishman, G. J.; Harmon, A.; Benton, E. V.; Frank, A. L.; Heinrich, Wolfgang

    1991-01-01

    The Long Duration Exposure Facility (LDEF) was exposed to several sources of ionizing radiation while in orbit. The principal ones were trapped belt protons and electrons, galactic cosmic rays, and albedo particles (protons and neutrons) from the atmosphere. Large solar flares in 1989 may have caused a small contribution. Prior to the recovery of the spacecraft, a number of calculations and estimates were made to predict the radiation exposure of the spacecraft and experiments. These were made to assess whether measurable radiation effects might exist, and to plan the analysis of the large number of radiation measurements available on the LDEF. Calculations and estimates of total dose, particle fluences, linear energy transfer spectra, and induced radioactivity were made. The principal sources of radiation is described, and the preflight predictions are summarized.

  15. Truffles decontamination treatment by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Adamo, M.; Capitani, D.; Mannina, L.; Cristinzio, M.; Ragni, P.; Tata, A.; Coppola, R.

    2004-09-01

    A research project, funded by the Italian Ministry of Research and the European Union, is in progress aimed to develop processes to enhance, by irradiation, the safety and the wholesomeness of fresh products relevant for Italian food industry. Irradiation was performed on truffles, since the bacterial contamination impairs their trade in foreign countries. The microbial population and the shelf life under refrigeration were studied either on samples untreated or on samples submitted to γ-rays in a 1-2.5 kGy dose range. The effect of the treatment was monitored by UV and NMR techniques. Total microbial population and the shelf life prolongation were investigated. The synergistic effect of the dose, the packaging under vacuum and the storage/irradiation temperature resulted in a direct effect on the microbial load, spoilage and shelf life. After the irradiation, small variations in the intensity of some NMR resonances due to aromatic compounds and other unassigned compounds were observed. As confirmed by UV spectrophotometric data, these phenomena seemed to originate from a small degradation of polyphenols; the induced growth of soluble phenols suggested that the 1.5 kGy dose can be considered as the radiation dose threshold beyond which clear chemical modifications on truffles appear.

  16. Prediction of LDEF ionizing radiation environment

    NASA Technical Reports Server (NTRS)

    Watts, John W.; Parnell, T. A.; Derrickson, James H.; Armstrong, T. W.; Benton, E. V.

    1992-01-01

    The Long Duration Exposure Facility (LDEF) spacecraft flew in a 28.5 deg inclination circular orbit with an altitude in the range from 172 to 258.5 nautical miles. For this orbital altitude and inclination two components contribute most of the penetrating charge particle radiation encountered - the galactic cosmic rays and the geomagnetically trapped Van Allen protons. Where shielding is less than 1.0 g/sq cm geomagnetically trapped electrons make a significant contribution. The 'Vette' models together with the associated magnetic filed models were used to obtain the trapped electron and proton fluences. The mission proton doses were obtained from the fluence using the Burrell proton dose program. For the electron and bremsstrahlung dose we used the Marshall Space Flight Center (MSFC) electron dose program. The predicted doses were in general agreement with those measured with on-board thermoluminescent detector (TLD) dosimeters. The NRL package of programs, Cosmic Ray Effects on MicroElectronics (CREME), was used to calculate the linear energy transfer (LET) spectrum due to galactic cosmic rays (GCR) and trapped protons for comparison with LDEF measurements.

  17. Risk calculations for hereditary effects of ionizing radiation in humans.

    PubMed

    Vogel, F

    1992-05-01

    A prediction of the extent to which an additional dose of ionizing radiation increases the natural germ cell mutation rate, and how much such an increase will affect the health status of future human populations is part of the service that human geneticists are expected to offer to human society. However, more detailed scrutiny of the difficulties involved reveals an extremely complex set of problems. A large number of questions arises before such a prediction can be given with confidence; many such questions cannot be answered at our present state of knowledge. However, such predictions have recently been attempted. The 1988 report of the United Nations Scientific Committee for the Effects of Atomic Radiation and the fifth report of the Committee on Biological Effects of Ionizing Radiation of the US National Research Council have presented a discussion of the human genetics problems involved. Empirical data from studies on children of highly radiation-exposed parents, e.g. parents exposed to the atomic bombs of Hiroshima and Nagasaki, or parents belonging to populations living on soil with high background radiation, have been mentioned in this context. Whereas precise predictions are impossible as yet because of deficiencies in our knowledge of medical genetics at various levels, the bulk of the existing evidence points to only small effects of low or moderate radiation doses, effects that will probably be buried in the "background noise" of changing patterns of human morbidity and mortality. PMID:1587523

  18. [Integral estimation of genetic effects of ionizing radiation].

    PubMed

    Shevchenko, V A

    1997-01-01

    A system of criteria (direct, indirect, extrapolational, integral, populational, evolutional) has been proposed to estimate the consequences of irradiation of flora, fauna and human population. This system makes it possible to obtain the most comprehensive estimate of genetic effects from exposure of live organisms to ionizing radiations. An attempt has been made to use extrapolational approaches for assessing the genetic risk on the basis of the results of cytogenetic examination of the human population in a number of regions exposed to the action of ionizing radiations as a result of the Chernobyl accident, in connection with the activity of the chemical plant Mayak in the Chelyabinsk region, nuclear explosions at the Semipalatinsk nuclear test site, the accident at the Three Mile Island nuclear power plant in the U.S.A. PMID:9599614

  19. Comparisons organized by Ionizing Radiation Metrology Laboratory of FTMC, Lithuania.

    PubMed

    Gudelis, A; Gorina, I

    2016-03-01

    The newly established Ionizing Radiation Metrology Laboratory of the National Metrology Institute (FTMC) in Lithuania organized four comparisons in the field of low-level radioactivity measurements in water. For gamma-ray emitters, the activity concentration in the samples was in the range 1-25Bq/kg, while for tritium it was around 2Bq/g. The assigned values of all comparisons were traceable to the primary standards of the Czech Metrology Institute (CMI). PMID:26585643

  20. Ionizing radiations, underground world and nuclear tests in Algeria

    NASA Astrophysics Data System (ADS)

    Chama, Allel

    2010-05-01

    Today, the exposure to ionizing radiations, is still a real great physical hazard in the world at various levels until the nuclear tests which led to a rich and lawful debate, and needs the installation of preventive rules through technical and medical aspects during the use of the radioactive sources, (theradioprotection). Concerning the occupational health, the pathology of the ionizing radiations is repaired under occupational disease. Our interest is to highlight this physical hazard, which represents an important chapter of the occupational pathology in its effects and prevention of the workers exposed in Algeria. The second aim of the paper is to highlight the historical aspect of the risk of ionizing radiations and consequences causes by the French nuclear tests in In Eker (underground galleries of the mountain of Hoggar in the south of Algeria in 1961), whose effects present a great damage on the health of the Algerian captive, and "workers", indigenous population and environment until now. This event deserves its place as much as that of Hiroshima and Nagasaki (1945).

  1. DNA-nuclear matrix interactions and ionizing radiation sensitivity

    SciTech Connect

    Schwartz, J.L. Chicago Univ., IL . Dept. of Radiation and Cellular Oncology); Vaughan, A.T.M. . Dept. of Radiotherapy)

    1993-01-01

    The association between inherent ionizing radiation sensitivity and DNA supercoil unwinding in mammalian cells suggests that the DNA-nuclear matrix attachment region (MAR) plays an important role in radiation response. In radioresistant cells, the MAR structure may exist in a more stable, open configuration, limiting DNA unwinding following strand break induction and maintaining DNA ends in close proximity for more rapid and accurate rejoining. In addition, the open configuration at these matrix attachment sites may serve to facilitate rapid DNA processing of breaks by providing (1) sites for repair proteins to collect and (2) energy to drive enzymatic reactions.

  2. DNA-nuclear matrix interactions and ionizing radiation sensitivity

    SciTech Connect

    Schwartz, J.L. |; Vaughan, A.T.M.

    1993-03-01

    The association between inherent ionizing radiation sensitivity and DNA supercoil unwinding in mammalian cells suggests that the DNA-nuclear matrix attachment region (MAR) plays an important role in radiation response. In radioresistant cells, the MAR structure may exist in a more stable, open configuration, limiting DNA unwinding following strand break induction and maintaining DNA ends in close proximity for more rapid and accurate rejoining. In addition, the open configuration at these matrix attachment sites may serve to facilitate rapid DNA processing of breaks by providing (1) sites for repair proteins to collect and (2) energy to drive enzymatic reactions.

  3. Ionizing Radiation-Induced Cataract in Interventional Cardiology Staff

    PubMed Central

    Bitarafan Rajabi, Ahmad; Noohi, Feridoun; Hashemi, Hassan; Haghjoo, Majid; Miraftab, Mohammad; Yaghoobi, Nahid; Rastgou, Fereydon; Malek, Hadi; Faghihi, Hoshang; Firouzabadi, Hassan; Asgari, Soheila; Rezvan, Farhad; Khosravi, Hamidreza; Soroush, Sara; Khabazkhoob, Mehdi

    2015-01-01

    Background: The use of ionizing radiation has led to advances in medical diagnosis and treatment. Objectives: The purpose of this study was to determine the risk of radiation cataractogenesis in the interventionists and staff performing various procedures in different interventional laboratories. Patients and Methods: This cohort study included 81 interventional cardiology staff. According to the working site, they were classified into 5 groups. The control group comprised 14 professional nurses who did not work in the interventional sites. Participants were assigned for lens assessment by two independent trained ophthalmologists blinded to the study. Results: The electrophysiology laboratory staff received higher doses of ionizing radiation (17.2 ± 11.9 mSv; P < 0.001). There was a significant positive correlation between the years of working experience and effective dose in the lens (P < 0.001). In general, our findings showed that the incidence of lens opacity was 79% (95% CI, 69.9-88.1) in participants with exposure (the case group) and our findings showed that the incidence of lenses opacity was 7.1% (95% CI:2.3-22.6) with the relative risk (RR) of 11.06 (P < 0.001). Conclusions: We believe that the risk of radiation-induced cataract in cardiology interventionists and staff depends on their work site. As the radiation dose increases, the prevalence of posterior eye changes increases. PMID:25789258

  4. Chelation of lysosomal iron protects against ionizing radiation.

    PubMed

    Berndt, Carsten; Kurz, Tino; Selenius, Markus; Fernandes, Aristi P; Edgren, Margareta R; Brunk, Ulf T

    2010-12-01

    Ionizing radiation causes DNA damage and consequent apoptosis, mainly due to the production of hydroxyl radicals (HO•) that follows radiolytic splitting of water. However, superoxide (O2•-) and H2O2 also form and induce oxidative stress with resulting LMP (lysosomal membrane permeabilization) arising from iron-catalysed oxidative events. The latter will contribute significantly to radiation-induced cell death and its degree largely depends on the quantities of lysosomal redox-active iron present as a consequence of autophagy and endocytosis of iron-rich compounds. Therefore radiation sensitivity might be depressed by lysosome-targeted iron chelators. In the present study, we have shown that cells in culture are significantly protected from ionizing radiation damage if initially exposed to the lipophilic iron chelator SIH (salicylaldehyde isonicotinoyl hydrazone), and that this effect is based on SIH-dependent lysosomal stabilization against oxidative stress. According to its dose-response-modifying effect, SIH is a most powerful radioprotector and a promising candidate for clinical application, mainly to reduce the radiation sensitivity of normal tissue. We propose, as an example, that inhalation of SIH before each irradiation session by patients undergoing treatment for lung malignancies would protect normally aerated lung tissue against life-threatening pulmonary fibrosis, whereas the sensitivity of malignant lung tumours, which usually are non-aerated, will not be affected by inhaled SIH. PMID:20846118

  5. Delayed effects of ionizing radiation on the ear

    SciTech Connect

    Bohne, B.A.; Marks, J.E.; Glasgow, G.P.

    1985-07-01

    The question of damage to the ear from exposure to ionizing radiation was addressed by exposing groups of chinchillas to fractioned doses of radiation (2 Gy per day) for total doses ranging from 40 to 90 Gy. In order to allow any delayed effects of radiation to become manifest, the animals were sacrificed two years after completion of treatment and their temporal bones were prepared for microscopic examination. The most pronounced effect of treatment was degeneration of sensory and supporting cells and loss of eighth nerve fibers in the organ of Corti. Damage increased with increasing dose of radiation. The degree of damage found in many of these ears was of sufficient magnitude to produce a permanent sensorineural hearing loss.

  6. Total ionizing dose (TID) effects of γ ray radiation on switching behaviors of Ag/AlO x /Pt RRAM device

    PubMed Central

    2014-01-01

    The total ionizing dose (TID) effects of 60Co γ ray radiation on the resistive random access memory (RRAM) devices with the structure of Ag/AlO x /Pt were studied. The resistance in low resistance state (LRS), set voltage, and reset voltage are almost immune to radiation, whereas the initial resistance, resistance at high resistance state (HRS), and forming voltage were significantly impacted after radiation due to the radiation-induced holes. A novel hybrid filament model is proposed to explain the radiation effects, presuming that holes are co-operated with Ag ions to build filaments. In addition, the thermal coefficients of the resistivity in LRS can support this hybrid filament model. The Ag/AlO x /Pt RRAM devices exhibit radiation immunity to a TID up to 1 Mrad(Si) and are highly suitable for radiation-hard electronics applications. PMID:25246866

  7. 21 CFR 179.26 - Ionizing radiation for the treatment of food.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Ionizing radiation for the treatment of food. 179.26 Section 179.26 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) IRRADIATION IN THE PRODUCTION, PROCESSING AND HANDLING OF FOOD Radiation and Radiation Sources § 179.26 Ionizing radiation for...

  8. A high dynamic range current dosimeter for space ionization radiation measurement

    NASA Astrophysics Data System (ADS)

    Lei, Sheng-jie; Wei, Zhi-yong; Fang, Mei-hua; Chen, Guo-yun; Zhang, Zi-xia; Huang, San-bo

    2011-08-01

    A dosimeter for space ionization radiation field is developed, energy deposited in the sensitivity volume of ionization chamber induces an output current signal as weak as 10-14A, and the dynamic range of the signal is very high. Now, an ionization chamber is designed and a variable gain current feedback preamp module is designed for the weak output current amplification is connected to output of the ionization chamber anode. The amplifier module includes I-V converter with T shaped resistance net, zero correct circuit, low pass filter, voltage linear amplifier circuit, gain control circuit and voltage output circuit. A complete analysis of this current preamp with respect to its circuit structure, dynamic properties, its equivalent input noise and the temperature effect is given. The effects of stray impedances on the behavior of the current feedback preamp are taken into account and the techniques necessary to achieve an optimum stable electrometer, with respect to noise, Dc drift, leakage currents, are applied. Experiments show that the energy of dosimeter deposited in the sensitivity volume of ionization chamber induces an output current signal as weak as 10-14A, the current preamp can detect weak current effectively with the range from 100fA to 10μA through switchable gain.

  9. Eye Lens Opacities Among Physicians Occupationally Exposed to Ionizing Radiation.

    PubMed

    Auvinen, Anssi; Kivelä, Tero; Heinävaara, Sirpa; Mrena, Samy

    2015-08-01

    We compared the frequency of lens opacities among physicians with and without occupational exposure to ionizing radiation, and estimated dose-response between cumulative dose and opacities. We conducted ophthalmologic examinations of 21 physicians with occupational exposure to radiation and 16 unexposed physicians. Information on cumulative radiation doses (mean 111 mSv) was based on dosimeter readings recorded in a national database on occupational exposures. Lens changes were evaluated using the Lens Opacities Classification System II, with an emphasis on posterior subcapsular (PSC) and cortical changes. Among the exposed physicians, the prevalences of cortical and PSC changes were both 11% (3/21), and the corresponding frequencies in the unexposed group were 44% (n = 7) and 6% (n = 1). For dose-response analysis, the data were pooled with 29 exposed physicians from our previous study. No association of either type of lens changes with cumulative recorded dose was observed. Our findings do not indicate an increased frequency of lens opacities in physicians with occupational exposure to ionizing radiation. However, the subjects in this study have received relatively low doses and therefore the results do not exclude small increases in lens opacities or contradict the studies reporting increases among interventional cardiologists with materially higher cumulative doses. PMID:25868644

  10. 29 CFR 570.57 - Exposure to radioactive substances and to ionizing radiations (Order 6).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Exposure to radioactive substances and to ionizing... to Their Health or Well-Being § 570.57 Exposure to radioactive substances and to ionizing radiations... radioactive substances and to ionizing radiations are particularly hazardous and detrimental to health...

  11. 29 CFR 570.57 - Exposure to radioactive substances and to ionizing radiations (Order 6).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Exposure to radioactive substances and to ionizing... to Their Health or Well-Being § 570.57 Exposure to radioactive substances and to ionizing radiations... radioactive substances and to ionizing radiations are particularly hazardous and detrimental to health...

  12. 29 CFR 570.57 - Exposure to radioactive substances and to ionizing radiations (Order 6).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Exposure to radioactive substances and to ionizing... to Their Health or Well-Being § 570.57 Exposure to radioactive substances and to ionizing radiations... radioactive substances and to ionizing radiations are particularly hazardous and detrimental to health...

  13. 29 CFR 570.57 - Exposure to radioactive substances and to ionizing radiations (Order 6).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Exposure to radioactive substances and to ionizing... to Their Health or Well-Being § 570.57 Exposure to radioactive substances and to ionizing radiations... radioactive substances and to ionizing radiations are particularly hazardous and detrimental to health...

  14. 29 CFR 570.57 - Exposure to radioactive substances and to ionizing radiations (Order 6).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false Exposure to radioactive substances and to ionizing... to Their Health or Well-Being § 570.57 Exposure to radioactive substances and to ionizing radiations... radioactive substances and to ionizing radiations are particularly hazardous and detrimental to health...

  15. Ionizing Radiation-Induced Endothelial Cell Senescence and Cardiovascular Diseases.

    PubMed

    Wang, Yingying; Boerma, Marjan; Zhou, Daohong

    2016-08-01

    Exposure to ionizing radiation induces not only apoptosis but also senescence. While the role of endothelial cell apoptosis in mediating radiation-induced acute tissue injury has been extensively studied, little is known about the role of endothelial cell senescence in the pathogenesis of radiation-induced late effects. Senescent endothelial cells exhibit decreased production of nitric oxide and expression of thrombomodulin, increased expression of adhesion molecules, elevated production of reactive oxygen species and inflammatory cytokines and an inability to proliferate and form capillary-like structures in vitro. These findings suggest that endothelial cell senescence can lead to endothelial dysfunction by dysregulation of vasodilation and hemostasis, induction of oxidative stress and inflammation and inhibition of angiogenesis, which can potentially contribute to radiation-induced late effects such as cardiovascular diseases (CVDs). In this article, we discuss the mechanisms by which radiation induces endothelial cell senescence, the roles of endothelial cell senescence in radiation-induced CVDs and potential strategies to prevent, mitigate and treat radiation-induced CVDs by targeting senescent endothelial cells. PMID:27387862

  16. Ionizing Radiation-Induced Endothelial Cell Senescence and Cardiovascular Diseases

    PubMed Central

    Wang, Yingying; Boerma, Marjan; Zhou, Daohong

    2016-01-01

    Exposure to ionizing radiation induces not only apoptosis but also senescence. While the role of endothelial cell apoptosis in mediating radiation-induced acute tissue injury has been extensively studied, little is known about the role of endothelial cell senescence in the pathogenesis of radiation-induced late effects. Senescent endothelial cells exhibit decreased production of nitric oxide and expression of thrombomodulin, increased expression of adhesion molecules, elevated production of reactive oxygen species and inflammatory cytokines and an inability to proliferate and form capillary-like structures in vitro. These findings suggest that endothelial cell senescence can lead to endothelial dysfunction by dysregulation of vasodilation and hemostasis, induction of oxidative stress and inflammation and inhibition of angiogenesis, which can potentially contribute to radiation-induced late effects such as cardiovascular diseases (CVDs). In this article, we discuss the mechanisms by which radiation induces endothelial cell senescence, the roles of endothelial cell senescence in radiation-induced CVDs and potential strategies to prevent, mitigate and treat radiation-induced CVDs by targeting senescent endothelial cells. PMID:27387862

  17. The effects of ionizing radiation on aquatic organisms

    SciTech Connect

    Templeton, W.L.; Blaylock, B.G.

    1990-09-01

    Scientific Committee {number sign}64-6 of the National Council on Radiation Protection (NCRP) of the United States has recently completed a review of the literature on the effects of ionizing radiation on aquatic organisms (NCRP 1990). In this report, the NCRP provides guidance for a dose rate below which deleterious effects to aquatic organisms are acceptably low; reviews a series of simple dosimetric models that can be applied to demonstrate compliance with such a dose rate; provides examples of the application of the models to contaminated aquatic environments; and evaluates the validity of the statement of the International Commission on Radiation Protection (ICRP 1977) that if man is adequately protected then other living things are also likely to be sufficiently protected.'' 6 refs.

  18. Infrared luminescence for real time ionizing radiation detection

    SciTech Connect

    Veronese, Ivan Mattia, Cristina De; Cantone, Marie Claire; Fasoli, Mauro; Chiodini, Norberto; Vedda, Anna; Mones, Eleonora

    2014-08-11

    Radio-luminescence (RL) optical fiber sensors enable a remote, punctual, and real time detection of ionizing radiation. However, the employment of such systems for monitoring extended radiation fields with energies above the Cerenkov threshold is still challenging, since a spurious luminescence, namely, the “stem effect,” is also generated in the passive fiber portion exposed to radiation. Here, we present experimental measurements on Yb-doped silica optical fibers irradiated with photon fields of different energies and sizes. The results demonstrate that the RL of Yb{sup 3+}, displaying a sharp emission line at about 975 nm, is free from any spectral superposition with the spurious luminescence. This aspect, in addition with the suitable linearity, reproducibility, and sensitivity properties of the Yb-doped fibers, paves the way to their use in applications where an efficient stem effect removal is required.

  19. Ionizing radiation and kidney cancer among Japanese atomic bomb survivors.

    PubMed

    Richardson, David B; Hamra, Ghassan

    2010-06-01

    Understanding of the role of radiation as a cause of kidney cancer remains limited. The most common types of kidney cancer are renal cell carcinoma and renal pelvis carcinoma. It has been posited that these entities differ in their degree of radiogenicity. Recent analyses of cancer incidence and mortality in the Life Span Study (LSS) of Japanese atomic bomb survivors have examined associations between ionizing radiation and renal cell carcinoma, but these analyses have not reported results for cancer of the renal pelvis and ureters. This paper reports the results of analyses of kidney cancer incidence during the period 1958-1998 among 105,427 atomic bomb survivors. Poisson regression methods were used to derive estimates of associations between radiation dose (in sievert, Sv) and cancer of the renal parenchyma (n = 167), and cancer of the renal pelvis and ureter (n = 80). Heterogeneity by cancer site was tested by joint modeling of cancer risks. Radiation dose was positively associated with cancers of the renal pelvis and ureter [excess relative rate (ERR)/Sv = 1.65; 90% confidence interval (CI): 0.37, 3.78]. The magnitude of this association was larger than the estimated association between radiation dose and cancer of the renal parenchyma (ERR/Sv = 0.27; 90% CI = -0.19, 0.98). While the association between radiation and cancer of the renal parenchyma was of greater magnitude at ages <55 years (ERR/Sv = 2.82; 90% CI = 0.45, 8.89) than at older attained ages (ERR/Sv = -0.11; 90% CI = nd, 0.53), the association between radiation and cancers of the renal pelvis and ureter varied minimally across these categories of attained age. A test of heterogeneity of type-specific risks provides modest support for the conclusion that risks vary by kidney cancer site (LRT = 2.34, 1 d.f., P = 0.13). Since some studies of radiation-exposed populations examine these sites in aggregate, results were also derived for the combined category of cancer of the renal parenchyma, renal

  20. Intrinsic radiation resistance in human chondrosarcoma cells

    SciTech Connect

    Moussavi-Harami, Farid; Mollano, Anthony; Martin, James A.; Ayoob, Andrew; Domann, Frederick E.; Gitelis, Steven; Buckwalter, Joseph A. . E-mail: joseph-buckwalter@uiowa.edu

    2006-07-28

    Human chondrosarcomas rarely respond to radiation treatment, limiting the options for eradication of these tumors. The basis of radiation resistance in chondrosarcomas remains obscure. In normal cells radiation induces DNA damage that leads to growth arrest or death. However, cells that lack cell cycle control mechanisms needed for these responses show intrinsic radiation resistance. In previous work, we identified immortalized human chondrosarcoma cell lines that lacked p16{sup ink4a}, one of the major tumor suppressor proteins that regulate the cell cycle. We hypothesized that the absence of p16{sup ink4a} contributes to the intrinsic radiation resistance of chondrosarcomas and that restoring p16{sup ink4a} expression would increase their radiation sensitivity. To test this we determined the effects of ectopic p16{sup ink4a} expression on chondrosarcoma cell resistance to low-dose {gamma}-irradiation (1-5 Gy). p16{sup ink4a} expression significantly increased radiation sensitivity in clonogenic assays. Apoptosis did not increase significantly with radiation and was unaffected by p16{sup ink4a} transduction of chondrosarcoma cells, indicating that mitotic catastrophe, rather than programmed cell death, was the predominant radiation effect. These results support the hypothesis that p16{sup ink4a} plays a role in the radiation resistance of chondrosarcoma cell lines and suggests that restoring p16 expression will improve the radiation sensitivity of human chondrosarcomas.

  1. Ionizing radiation, antioxidant response and oxidative damage: A meta-analysis.

    PubMed

    Einor, D; Bonisoli-Alquati, A; Costantini, D; Mousseau, T A; Møller, A P

    2016-04-01

    One mechanism proposed as a link between exposure to ionizing radiation and detrimental effects on organisms is oxidative damage. To test this hypothesis, we surveyed the scientific literature on the effects of chronic low-dose ionizing radiation (LDIR) on antioxidant responses and oxidative damage. We found 40 publications and 212 effect sizes for antioxidant responses and 288 effect sizes for effects of oxidative damage. We performed a meta-analysis of signed and unsigned effect sizes. We found large unsigned effects for both categories (0.918 for oxidative damage; 0.973 for antioxidant response). Mean signed effect size weighted by sample size was 0.276 for oxidative damage and -0.350 for antioxidant defenses, with significant heterogeneity among effects for both categories, implying that ionizing radiation caused small to intermediate increases in oxidative damage and small to intermediate decreases in antioxidant defenses. Our estimates are robust, as shown by very high fail-safe numbers. Species, biological matrix (tissue, blood, sperm) and age predicted the magnitude of effects for oxidative damage as well as antioxidant response. Meta-regression models showed that effect sizes for oxidative damage varied among species and age classes, while effect sizes for antioxidant responses varied among species and biological matrices. Our results are consistent with the description of mechanisms underlying pathological effects of chronic exposure to LDIR. Our results also highlight the importance of resistance to oxidative stress as one possible mechanism associated with variation in species responses to LDIR-contaminated areas. PMID:26851726

  2. Influence of solvothermal synthesis conditions in BiSI nanostructures for application in ionizing radiation detectors

    NASA Astrophysics Data System (ADS)

    Aguiar, I.; Mombrú, M.; Pérez Barthaburu, M.; Bentos Pereira, H.; Fornaro, L.

    2016-02-01

    BiSI belongs to the A V B VI C VII chalcohalides group of compounds. These compounds show several interesting properties such as ferroelectricity, piezoelectricity along the c axis, and photoconductivity. Moreover, BiSI is a potential semiconductor material for room-temperature gamma and x-ray detection, given its band gap of 1.57 eV and its high density, 6.41 g cm-3. In this work we present BiSI nanostructures synthesized by the solvothermal method with the intention of using them for ionizing radiation detection. The solvent was varied to study its influence in morphology, particle size and size distribution. Three different conditions were tested, using either water, monoethylene glycol and a mixture of both solvents. Nanostructures were characterized by XRD to determine the phase obtained and reaction completeness; TEM was used to observe nanostructures morphology, size, size distribution and crystallinity; and finally FT-IR diffuse reflectance was used to study monoethylene glycol presence in the samples. Nanorods in the range of 100-200 nm width were obtained in all samples, but round nanoparticles of around 10 nm in diameter were also detected in samples synthesized only with monoethylene glycol. Samples synthesized in monoethylene glycol were used to fabricate pellets to construct detectors. The detectors responded to ionizing radiation and a resistivity in the order of 1013 Ω cm was estimated. This work proposes, to our knowledge, the first study of BiSI for its application in ionizing radiation detection.

  3. 21 CFR 579.22 - Ionizing radiation for treatment of animal diets.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., AND HANDLING OF ANIMAL FEED AND PET FOOD Radiation and Radiation Sources § 579.22 Ionizing radiation... formulated to account for nutritional loss Microbial disinfection, control or elimination (2) If...

  4. A link between solar events and congenital malformations: Is ionizing radiation enough to explain it?

    NASA Astrophysics Data System (ADS)

    Overholt, Andrew C.; Melott, Adrian L.; Atri, Dimitra

    2015-03-01

    Cosmic rays are known to cause biological effects directly and through ionizing radiation produced by their secondaries. These effects have been detected in airline crews and other specific cases where members of the population are exposed to above average secondary fluxes. Recent work has found a correlation between solar particle events and congenital malformations. In this work we use the results of computational simulations to approximate the ionizing radiation from such events as well as longer-term increases in cosmic ray flux. We find that the amounts of ionizing radiation produced by these events are insufficient to produce congenital malformations under the current paradigm regarding muon ionizing radiation. We believe that further work is needed to determine the correct ionizing radiation contribution of cosmogenic muons. We suggest that more extensive measurements of muon radiation effects may show a larger contribution to ionizing radiation dose than currently assumed.

  5. Characterization of Silicon-On-Diamond chip with ionizing radiation

    NASA Astrophysics Data System (ADS)

    Servoli, L.; Brandi, F.; Carzino, R.; Citroni, M.; Fanetti, S.; Lagomarsino, S.; Parrini, G.; Passeri, D.; Sciortino, S.; Scorzoni, A.

    2014-04-01

    In this work we report on the characterization with ionizing radiation sources of a CMOS active pixel radiation sensor (RAPS03) thinned down to 40um and bonded to a slice of diamond to form a rugged Silicon-On-Diamond structure. The bonding process is based on an innovative laser technique which scans the silicon-diamond interface with a 20 ps pulsed 355 nm laser beam. The goal of the work is to demonstrate that the bonding procedure does not damage the CMOS devices, paving the way for a possible alternative to bump bonding procedures between diamond substrates and readout chips. To this purpose, the Silicon-On-Diamond device and a standard (e.g. un-thinned) RAPS03 sensor have been tested in parallel with and without ionizing radiation sources (photons, electrons) to compare their characteristics and to study their differences. The Silicon-On-Diamond device has shown to be fully functional and no differences have been found between the responses of the two sensors, within the statistical variations due to the CMOS fabrication process.

  6. Acute and Chronic Cutaneous Reactions to Ionizing Radiation Therapy.

    PubMed

    Bray, Fleta N; Simmons, Brian J; Wolfson, Aaron H; Nouri, Keyvan

    2016-06-01

    Ionizing radiation is an important treatment modality for a variety of malignant conditions. However, development of radiation-induced skin changes is a significant adverse effect of radiation therapy (RT). Cutaneous repercussions of RT vary considerably in severity, course, and prognosis. When they do occur, cutaneous changes to RT are commonly graded as acute, consequential-late, or chronic. Acute reactions can have severe sequelae that impact quality of life as well as cancer treatment. Thus, dermatologists should be informed about these adverse reactions, know how to assess their severity and be able to determine course of management. The majority of measures currently available to prevent these acute reactions are proper skin hygiene and topical steroids, which limit the severity and decrease symptoms. Once acute cutaneous reactions develop, they are treated according to their severity. Treatments are similar to those used in prevention, but incorporate wound care management that maintains a moist environment to hasten recovery. Chronic changes are a unique subset of adverse reactions to RT that may develop months to years following treatment. Chronic radiation dermatitis is often permanent, progressive, and potentially irreversible with substantial impact on quality of life. Here, we also review the etiology, clinical manifestations, pathogenesis, prevention, and management of late-stage cutaneous reactions to radiotherapy, including chronic radiation dermatitis and radiation-induced fibrosis. PMID:27250839

  7. The susceptibility of TaOx-based memristors to high dose rate ionizing radiation and total ionizing dose

    SciTech Connect

    McLain, Michael Lee; Sheridan, Timothy J.; Hjalmarson, Harold Paul; Mickel, Patrick R.; Hanson, Donald J.; McDonald, Joseph K.; Hughart, David Russell; Marinella, Matthew J.

    2014-11-11

    This paper investigates the effects of high dose rate ionizing radiation and total ionizing dose (TID) on tantalum oxide (TaOx) memristors. Transient data were obtained during the pulsed exposures for dose rates ranging from approximately 5.0 ×107 rad(Si)/s to 4.7 ×108 rad(Si)/s and for pulse widths ranging from 50 ns to 50 μs. The cumulative dose in these tests did not appear to impact the observed dose rate response. Static dose rate upset tests were also performed at a dose rate of ~3.0 ×108 rad(Si)/s. This is the first dose rate study on any type of memristive memory technology. In addition to assessing the tolerance of TaOx memristors to high dose rate ionizing radiation, we also evaluated their susceptibility to TID. The data indicate that it is possible for the devices to switch from a high resistance off-state to a low resistance on-state in both dose rate and TID environments. The observed radiation-induced switching is dependent on the irradiation conditions and bias configuration. Furthermore, the dose rate or ionizing dose level at which a device switches resistance states varies from device to device; the enhanced susceptibility observed in some devices is still under investigation. As a result, numerical simulations are used to qualitatively capture the observed transient radiation response and provide insight into the physics of the induced current/voltages.

  8. Radiation protection and dosimetry issues in the medical applications of ionizing radiation

    NASA Astrophysics Data System (ADS)

    Vaz, Pedro

    2014-11-01

    The technological advances that occurred during the last few decades paved the way to the dissemination of CT-based procedures in radiology, to an increasing number of procedures in interventional radiology and cardiology as well as to new techniques and hybrid modalities in nuclear medicine and in radiotherapy. These technological advances encompass the exposure of patients and medical staff to unprecedentedly high dose values that are a cause for concern due to the potential detrimental effects of ionizing radiation to the human health. As a consequence, new issues and challenges in radiological protection and dosimetry in the medical applications of ionizing radiation have emerged. The scientific knowledge of the radiosensitivity of individuals as a function of age, gender and other factors has also contributed to raising the awareness of scientists, medical staff, regulators, decision makers and other stakeholders (including the patients and the public) for the need to correctly and accurately assess the radiation induced long-term health effects after medical exposure. Pediatric exposures and their late effects became a cause of great concern. The scientific communities of experts involved in the study of the biological effects of ionizing radiation have made a strong case about the need to undertake low dose radiation research and the International System of Radiological Protection is being challenged to address and incorporate issues such as the individual sensitivities, the shape of dose-response relationship and tissue sensitivity for cancer and non-cancer effects. Some of the answers to the radiation protection and dosimetry issues and challenges in the medical applications of ionizing radiation lie in computational studies using Monte Carlo or hybrid methods to model and simulate particle transport in the organs and tissues of the human body. The development of sophisticated Monte Carlo computer programs and voxel phantoms paves the way to an accurate

  9. Torin2 Suppresses Ionizing Radiation-Induced DNA Damage Repair.

    PubMed

    Udayakumar, Durga; Pandita, Raj K; Horikoshi, Nobuo; Liu, Yan; Liu, Qingsong; Wong, Kwok-Kin; Hunt, Clayton R; Gray, Nathanael S; Minna, John D; Pandita, Tej K; Westover, Kenneth D

    2016-05-01

    Several classes of inhibitors of the mammalian target of rapamycin (mTOR) have been developed based on its central role in sensing growth factor and nutrient levels to regulate cellular metabolism. However, its ATP-binding site closely resembles other phosphatidylinositol 3-kinase-related kinase (PIKK) family members, resulting in reactivity with these targets that may also be therapeutically useful. The ATP-competitive mTOR inhibitor, Torin2, shows biochemical activity against the DNA repair-associated proteins ATM, ATR and DNA-PK, which raises the possibility that Torin2 and related compounds might radiosensitize cancerous tumors. In this study Torin2 was also found to enhance ionizing radiation-induced cell killing in conditions where ATM was dispensable, confirming the requirement for multiple PIKK targets. Moreover, Torin2 did not influence the initial appearance of γ-H2AX foci after irradiation but significantly delayed the disappearance of radiation-induced γ-H2AX foci, indicating a DNA repair defect. Torin2 increased the number of radiation-induced S-phase specific chromosome aberrations and reduced the frequency of radiation-induced CtIP and Rad51 foci formation, suggesting that Torin2 works by blocking homologous recombination (HR)-mediated DNA repair resulting in an S-phase specific DNA repair defect. Accordingly, Torin2 reduced HR-mediated repair of I-Sce1-induced DNA damage and contributed to replication fork stalling. We conclude that radiosensitization of tumor cells by Torin2 is associated with disrupting ATR- and ATM-dependent DNA damage responses. Our findings support the concept of developing combination cancer therapies that incorporate ionizing radiation therapy and Torin2 or compounds with similar properties. PMID:27135971

  10. Optical remote diagnostics of atmospheric propagating beams of ionizing radiation

    DOEpatents

    Karl, Jr., Robert R.

    1990-01-01

    Data is obtained for use in diagnosing the characteristics of a beam of ionizing radiation, such as charged particle beams, neutral particle beams, and gamma ray beams. In one embodiment the beam is emitted through the atmosphere and produces nitrogen fluorescence during passage through air. The nitrogen fluorescence is detected along the beam path to provide an intensity from which various beam characteristics can be calculated from known tabulations. Optical detecting equipment is preferably located orthogonal to the beam path at a distance effective to include the entire beam path in the equipment field of view.

  11. Optical remote diagnostics of atmospheric propagating beams of ionizing radiation

    DOEpatents

    Karl JR., Robert R.

    1990-03-06

    Data is obtained for use in diagnosing the characteristics of a beam of ionizing radiation, such as charged particle beams, neutral particle beams, and gamma ray beams. In one embodiment the beam is emitted through the atmosphere and produces nitrogen fluorescence during passage through air. The nitrogen fluorescence is detected along the beam path to provide an intensity from which various beam characteristics can be calculated from known tabulations. Optical detecting equipment is preferably located orthogonal to the beam path at a distance effective to include the entire beam path in the equipment field of view.

  12. Accretion tori and cones of ionizing radiation in Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Acosta-Pulido, Jose A.; Perez-Fournon, Ismael; Calvani, Massimo; Wilson, Andrew S.

    1990-01-01

    The photoionization of extended narrow-line regions in Seyfert galaxies by the radiation produced in a thick accretion disk is studied. The emission-line spectrum is calculated for a range of black hole masses, varying the values of the ionization parameter and the disk size. It is found that models with a million solar masses fit observations of very large accretion disk sizes, while models with 10 million solar masses fit them better with smaller disks. The latter models are preferable since they have lower super-Eddington accretion rates.

  13. Developing of a New Atmospheric Ionizing Radiation (AIR) Model

    NASA Technical Reports Server (NTRS)

    Clem, John M.; deAngelis, Giovanni; Goldhagen, Paul; Wilson, John W.

    2003-01-01

    As a result of the research leading to the 1998 AIR workshop and the subsequent analysis, the neutron issues posed by Foelsche et al. and further analyzed by Hajnal have been adequately resolved. We are now engaged in developing a new atmospheric ionizing radiation (AIR) model for use in epidemiological studies and air transportation safety assessment. A team was formed to examine a promising code using the basic FLUKA software but with modifications to allow multiple charged ion breakup effects. A limited dataset of the ER-2 measurements and other cosmic ray data will be used to evaluate the use of this code.

  14. Multifluid Modeling of the Partially Ionized Chromosphere with Effects of Impact Ionization, Radiative Recombination and Charge Exchange

    NASA Astrophysics Data System (ADS)

    Maneva, Y. G.; Poedts, D. S.; Alvarez Laguna, A.; Lani, A.

    2015-12-01

    Neutrals play an important role in the evolution of the weakly ionized solar chromosphere where the number density of neutrals can vastly exceed the number density of protons. Therefore modeling the neutral-ion interactions and studying the effect of neutrals on the ambient plasma properties is an important task for better understanding the observed emission lines and the propagation of disturbances from the photosphere to the transition region and the corona. To pursue this goal we have developed two-fluid and three-fluid simulation setups to study the interaction between electrons, ions and neutrals in a reactive gravitationally stratified collisional media. The model considers the electrons and ions within the resistive MHD approach with Coulomb collisions and anisotropic heat flux determined by Braginskii's transport coefficients. The electromagnetic fields are evolved according to the full Maxwell equations, allowing for propagation of higher frequency waves neglected by the standard MHD approximation. Separate mass, momentum and energy conservation equations are considered for the neutrals and the interaction between the different fluids is determined by the chemical reactions, such as impact ionization, radiative recombination and charge exchange, provided as additional source terms. To initialize the system we consider an ideal gas equation of state with equal initial temperatures for the electrons, ions and the neutrals and different density profiles. The initial temperature and density profiles are height-dependent and follow VAL C atmospheric model for the solar chromosphere. We have searched for a chemical and collisional equilibrium between the ions and the neutrals in the hydrostatic case to avoid unphysical outflows and artificial heating induced by initial pressure imbalances. Next we consider ion-neutral interactions in magnetized plasma with an initial magnetic profile, corresponding to emerging magnetic funnel. Finally we include an external

  15. Ionizing Radiation Exposure and Basal Cell Carcinoma Pathogenesis.

    PubMed

    Li, Changzhao; Athar, Mohammad

    2016-03-01

    This commentary summarizes studies showing risk of basal cell carcinoma (BCC) development in relationship to environmental, occupational and therapeutic exposure to ionizing radiation (IR). BCC, the most common type of human cancer, is driven by the aberrant activation of hedgehog (Hh) signaling. Ptch, a tumor suppressor gene of Hh signaling pathway, and Smoothened play a key role in the development of radiation-induced BCCs in animal models. Epidemiological studies provide evidence that humans exposed to radiation as observed among the long-term, large scale cohorts of atomic bomb survivors, bone marrow transplant recipients, patients with tinea capitis and radiologic workers enhances risk of BCCs. Overall, this risk is higher in Caucasians than other races. People who were exposed early in life develop more BCCs. The enhanced IR correlation with BCC and not other common cutaneous malignancies is intriguing. The mechanism underlying these observations remains undefined. Understanding interactions between radiation-induced signaling pathways and those which drive BCC development may be important in unraveling the mechanism associated with this enhanced risk. Recent studies showed that Vismodegib, a Smoothened inhibitor, is effective in treating radiation-induced BCCs in humans, suggesting that common strategies are required for the intervention of BCCs development irrespective of their etiology. PMID:26930381

  16. CANCER RISKS ATTRIBUTABLE TO LOW DOSES OF IONIZING RADIATION - ASSESSING WHAT WE REALLY KNOW?

    EPA Science Inventory

    Cancer Risks Attributable to Low Doses of Ionizing Radiation - What Do We Really Know?

    Abstract
    High doses of ionizing radiation clearly produce deleterious consequences in humans including, but not exclusively, cancer induction. At very low radiation doses the situatio...

  17. Ionizing and Nonionizing Radiation Protection. Module SH-35. Safety and Health.

    ERIC Educational Resources Information Center

    Center for Occupational Research and Development, Inc., Waco, TX.

    This student module on ionizing and nonionizing radiation protection is one of 50 modules concerned with job safety and health. This module describes various types of ionizing and nonionizing radiation, and the situations in the workplace where potential hazards from radiation may exist. Following the introduction, 13 objectives (each keyed to a…

  18. Enhanced response of the Salmonella mutagenicity test to ionizing radiations

    SciTech Connect

    Roos, H.; Thomas, W.H.; Kellerer, A.M.

    1985-10-01

    Gamma-ray-induced reversions in the Ames Salmonella tester strain TA2638 have been studied for their dependence on a number of experimental parameters. It is shown that exposure to ionizing radiations soon after plating is not the procedure that yields results which correspond to those obtained in the standard utilization of the test with chemical mutagens. The ability to detect mutants is improved by irradiation 6 hr after the beginning of the incubation of the plated bacteria. This procedure has the double advantage of a markedly increased ratio of radiation-induced to spontaneous revertants and of resulting in substantial insensitivity to fluctuations in the number of bacteria initially plated. The reversion-doubling dose so obtained is 1.3 Gy; i.e., it is sufficiently small to disregard inactivation of the bacteria.

  19. DWARF GALAXIES WITH IONIZING RADIATION FEEDBACK. I. ESCAPE OF IONIZING PHOTONS

    SciTech Connect

    Kim, Ji-hoon; Krumholz, Mark R.; Goldbaum, Nathan J.; Wise, John H.; Turk, Matthew J.; Abel, Tom

    2013-10-01

    We describe a new method for simulating ionizing radiation and supernova feedback in the analogs of low-redshift galactic disks. In this method, which we call star-forming molecular cloud (SFMC) particles, we use a ray-tracing technique to solve the radiative transfer equation for ultraviolet photons emitted by thousands of distinct particles on the fly. Joined with high numerical resolution of 3.8 pc, the realistic description of stellar feedback helps to self-regulate star formation. This new feedback scheme also enables us to study the escape of ionizing photons from star-forming clumps and from a galaxy, and to examine the evolving environment of star-forming gas clumps. By simulating a galactic disk in a halo of 2.3 × 10{sup 11} M{sub ☉}, we find that the average escape fraction from all radiating sources on the spiral arms (excluding the central 2.5 kpc) fluctuates between 0.08% and 5.9% during a ∼20 Myr period with a mean value of 1.1%. The flux of escaped photons from these sources is not strongly beamed, but manifests a large opening angle of more than 60° from the galactic pole. Further, we investigate the escape fraction per SFMC particle, f{sub esc}(i), and how it evolves as the particle ages. We discover that the average escape fraction f{sub esc} is dominated by a small number of SFMC particles with high f{sub esc}(i). On average, the escape fraction from an SFMC particle rises from 0.27% at its birth to 2.1% at the end of a particle lifetime, 6 Myr. This is because SFMC particles drift away from the dense gas clumps in which they were born, and because the gas around the star-forming clumps is dispersed by ionizing radiation and supernova feedback. The framework established in this study brings deeper insight into the physics of photon escape fraction from an individual star-forming clump and from a galactic disk.

  20. Ionizing radiation and a wood-based biorefinery

    NASA Astrophysics Data System (ADS)

    Driscoll, Mark S.; Stipanovic, Arthur J.; Cheng, Kun; Barber, Vincent A.; Manning, Mellony; Smith, Jennifer L.; Sundar, Smith

    2014-01-01

    Woody biomass is widely available around the world. Cellulose is the major structural component of woody biomass and is the most abundant polymer synthesized by nature, with hemicellulose and lignin being second and third. Despite this great abundance, woody biomass has seen limited application outside of the paper and lumber industries. Its use as a feedstock for fuels and chemicals has been limited because of its highly crystalline structure, inaccessible morphology, and limited solubility (recalcitrance). Any economic use of woody biomass for the production of fuels and chemicals requires a "pretreatment" process to enhance the accessibility of the biomass to enzymes and/or chemical reagents. Electron beams (EB), X-rays, and gamma rays produce ions in a material which can then initiate chemical reactions and cleavage of chemical bonds. Such ionizing radiation predominantly scissions and degrades or depolymerizes both cellulose and hemicelluloses, less is known about its effects on lignin. This paper discusses how ionizing radiation can be used to make a wood-based biorefinery more environmentally friendly and profitable for its operators.

  1. Simulation of the radiation fields from ionizing radiation sources inside the containment in an accident

    SciTech Connect

    Kalugin, M. A.

    2010-12-15

    In the present work, a set of codes used for simulations of the radiation fields from ionizing radiation sources inside the containment in an accident is described. A method of evaluating the gamma dose rate from a space and energy distributed source is given. The dose rate is calculated by means of the design point kernel method and using buildup factors. The code MCU-REA with the ORIMCU module is used for the burnup calculations.

  2. Transcriptional Analysis of Deinococcus radiodurans Reveals Novel Small RNAs That Are Differentially Expressed under Ionizing Radiation

    PubMed Central

    Tsai, Chen-Hsun; Liao, Rick; Chou, Brendan

    2014-01-01

    Small noncoding RNAs (sRNAs) are posttranscriptional regulators that have been identified in multiple species and shown to play essential roles in responsive mechanisms to environmental stresses. The natural ability of specific bacteria to resist high levels of radiation has been of high interest to mechanistic studies of DNA repair and biomolecular protection. Deinococcus radiodurans is a model extremophile for radiation studies that can survive doses of ionizing radiation of >12,000 Gy, 3,000 times higher than for most vertebrates. Few studies have investigated posttranscriptional regulatory mechanisms of this organism that could be relevant in its general gene regulatory patterns. In this study, we identified 199 potential sRNA candidates in D. radiodurans by whole-transcriptome deep sequencing analysis and confirmed the expression of 41 sRNAs by Northern blotting and reverse transcriptase PCR (RT-PCR). A total of 8 confirmed sRNAs showed differential expression during recovery after acute ionizing radiation (15 kGy). We have also found and confirmed 7 sRNAs in Deinococcus geothermalis, a closely related radioresistant species. The identification of several novel sRNAs in Deinococcus bacteria raises important questions about the evolution and nature of global gene regulation in radioresistance. PMID:25548054

  3. Transcriptional analysis of Deinococcus radiodurans reveals novel small RNAs that are differentially expressed under ionizing radiation.

    PubMed

    Tsai, Chen-Hsun; Liao, Rick; Chou, Brendan; Contreras, Lydia M

    2015-03-01

    Small noncoding RNAs (sRNAs) are posttranscriptional regulators that have been identified in multiple species and shown to play essential roles in responsive mechanisms to environmental stresses. The natural ability of specific bacteria to resist high levels of radiation has been of high interest to mechanistic studies of DNA repair and biomolecular protection. Deinococcus radiodurans is a model extremophile for radiation studies that can survive doses of ionizing radiation of >12,000 Gy, 3,000 times higher than for most vertebrates. Few studies have investigated posttranscriptional regulatory mechanisms of this organism that could be relevant in its general gene regulatory patterns. In this study, we identified 199 potential sRNA candidates in D. radiodurans by whole-transcriptome deep sequencing analysis and confirmed the expression of 41 sRNAs by Northern blotting and reverse transcriptase PCR (RT-PCR). A total of 8 confirmed sRNAs showed differential expression during recovery after acute ionizing radiation (15 kGy). We have also found and confirmed 7 sRNAs in Deinococcus geothermalis, a closely related radioresistant species. The identification of several novel sRNAs in Deinococcus bacteria raises important questions about the evolution and nature of global gene regulation in radioresistance. PMID:25548054

  4. Review of using gallium nitride for ionizing radiation detection

    NASA Astrophysics Data System (ADS)

    Wang, Jinghui; Mulligan, Padhraic; Brillson, Leonard; Cao, Lei R.

    2015-09-01

    With the largest band gap energy of all commercial semiconductors, GaN has found wide application in the making of optoelectronic devices. It has also been used for photodetection such as solar blind imaging as well as ultraviolet and even X-ray detection. Unsurprisingly, the appreciable advantages of GaN over Si, amorphous silicon (a-Si:H), SiC, amorphous SiC (a-SiC), and GaAs, particularly for its radiation hardness, have drawn prompt attention from the physics, astronomy, and nuclear science and engineering communities alike, where semiconductors have traditionally been used for nuclear particle detection. Several investigations have established the usefulness of GaN for alpha detection, suggesting that when properly doped or coated with neutron sensitive materials, GaN could be turned into a neutron detection device. Work in this area is still early in its development, but GaN-based devices have already been shown to detect alpha particles, ultraviolet light, X-rays, electrons, and neutrons. Furthermore, the nuclear reaction presented by 14N(n,p)14C and various other threshold reactions indicates that GaN is intrinsically sensitive to neutrons. This review summarizes the state-of-the-art development of GaN detectors for detecting directly and indirectly ionizing radiation. Particular emphasis is given to GaN's radiation hardness under high-radiation fields.

  5. Review of using gallium nitride for ionizing radiation detection

    SciTech Connect

    Wang, Jinghui; Mulligan, Padhraic; Cao, Lei R.; Brillson, Leonard

    2015-09-15

    With the largest band gap energy of all commercial semiconductors, GaN has found wide application in the making of optoelectronic devices. It has also been used for photodetection such as solar blind imaging as well as ultraviolet and even X-ray detection. Unsurprisingly, the appreciable advantages of GaN over Si, amorphous silicon (a-Si:H), SiC, amorphous SiC (a-SiC), and GaAs, particularly for its radiation hardness, have drawn prompt attention from the physics, astronomy, and nuclear science and engineering communities alike, where semiconductors have traditionally been used for nuclear particle detection. Several investigations have established the usefulness of GaN for alpha detection, suggesting that when properly doped or coated with neutron sensitive materials, GaN could be turned into a neutron detection device. Work in this area is still early in its development, but GaN-based devices have already been shown to detect alpha particles, ultraviolet light, X-rays, electrons, and neutrons. Furthermore, the nuclear reaction presented by {sup 14}N(n,p){sup 14}C and various other threshold reactions indicates that GaN is intrinsically sensitive to neutrons. This review summarizes the state-of-the-art development of GaN detectors for detecting directly and indirectly ionizing radiation. Particular emphasis is given to GaN's radiation hardness under high-radiation fields.

  6. Positive associations between ionizing radiation and lymphoma mortality among men.

    PubMed

    Richardson, David B; Sugiyama, Hiromi; Wing, Steve; Sakata, Ritsu; Grant, Eric; Shimizu, Yukiko; Nishi, Nobuo; Geyer, Susan; Soda, Midori; Suyama, Akihiko; Kasagi, Fumiyoshi; Kodama, Kazunori

    2009-04-15

    The authors investigated the relation between ionizing radiation and lymphoma mortality in 2 cohorts: 1) 20,940 men in the Life Span Study, a study of Japanese atomic bomb survivors who were aged 15-64 years at the time of the bombings of Hiroshima and Nagasaki, and 2) 15,264 male nuclear weapons workers who were hired at the Savannah River Site in South Carolina between 1950 and 1986. Radiation dose-mortality trends were evaluated for all malignant lymphomas and for non-Hodgkin's lymphoma. Positive associations between lymphoma mortality and radiation dose under a 5-year lag assumption were observed in both cohorts (excess relative rates per sievert were 0.79 (90% confidence interval: 0.10, 1.88) and 6.99 (90% confidence interval: 0.96, 18.39), respectively). Exclusion of deaths due to Hodgkin's disease led to small changes in the estimates of association. In each cohort, evidence of a dose-response association was primarily observed more than 35 years after irradiation. These findings suggest a protracted induction and latency period for radiation-induced lymphoma mortality. PMID:19270049

  7. Polynucleotide kinase as a potential target for enhancing cytotoxicity by ionizing radiation and topoisomerase I inhibitors

    PubMed Central

    Bernstein, N. K.; Karimi-Busheri, F.; Rasouli-Nia, A.; Mani, R.; Dianov, G.; Glover, J. N. M.; Weinfeld, M.

    2010-01-01

    The cytotoxicity of many antineoplastic agents is due to their capacity to damage DNA and there is evidence indicating that DNA repair contributes to the cellular resistance to such agents. DNA strand breaks constitute a significant proportion of the lesions generated by a broad range of genotoxic agents, either directly, or during the course of DNA repair. Strand breaks that are caused by many agents including ionizing radiation, topoisomerase I inhibitors, and DNA repair glycosylases such as NEIL1 and NEIL2, often contain 5’-hydroxyl and/or 3’-phosphate termini. These ends must be converted to 5’-phosphate and 3’-hydroxyl termini in order to allow DNA polymerases and ligases to catalyze repair synthesis and strand rejoining. A key enzyme involved in this end-processing is polynucleotide kinase (PNK), which possesses two enzyme activities, a DNA 5’-kinase activity and a 3’-phosphatase activity. PNK participates in the single-strand break repair pathway and the non-homologous end joining pathway for double-strand break repair. RNAi-mediated down-regulation of PNK renders cells more sensitive to ionizing radiation and camptothecin, a topoisomerase I inhibitor. Structural analysis of PNK revealed the protein is composed of three domains, the kinase domain at the C-terminus, the phosphatase domain in the centre and a forkhead associated (FHA) domain at the N-terminus. The FHA domain plays a critical role in the binding of PNK to other DNA repair proteins. Thus each PNK domain may be a suitable target for small molecule inhibition to effectively reduce resistance to ionizing radiation and topoisomerase I inhibitors. PMID:18473721

  8. Radiation resistance of electro-optic polymer-based modulators

    SciTech Connect

    Taylor, Edward W.; Nichter, James E.; Nash, Fazio D.; Haas, Franz; Szep, Attila A.; Michalak, Richard J.; Flusche, Brian M.; Cook, Paul R.; McEwen, Tom A.; McKeon, Brian F.; Payson, Paul M.; Brost, George A.; Pirich, Andrew R.; Castaneda, Carlos; Tsap, Boris; Fetterman, Harold R.

    2005-05-16

    Mach-Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation.

  9. Simulation and Comparison of Martian Surface Ionization Radiation

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Zeitlin, Cary; Hassler, Donald M.; Cucinotta, Francis A.

    2013-01-01

    The spectrum of energetic particle radiation and corresponding doses at the surface of Mars is being characterized by the Radiation Assessment Detector (RAD), one of ten science instruments on the Mars Science Laboratory (MSL) Curiosity Rover. The time series of dose rate for the first 300 Sols after landing on Mars on August 6, 2012 is presented here. For the comparison to RAD measurements of dose rate, Martian surface ionization radiation is simulated by utilizing observed space quantities. The GCR primary radiation spectrum is calculated by using the Badhwar-O'Neill 2011 (BO11) galactic cosmic ray (GCR) model, which has been developed by utilizing all balloon and satellite GCR measurements since 1955 and the newer 1997-2012 Advanced Composition Explorer (ACE) measurements. In the BO11 model, solar modulation of the GCR primary radiation spectrum is described in terms of the international smoothed sunspot number and a time delay function. For the transport of the impingent GCR primary radiation through Mars atmosphere, a vertical distribution of atmospheric thickness at each elevation is calculated using the vertical profiles of atmospheric temperature and pressure made by Mars Global Surveyor measurements. At Gale Crater in the southern hemisphere, the seasonal variation of atmospheric thickness is accounted for the daily atmospheric pressure measurements of the MSL Rover Environmental Monitoring Station (REMS) by using low- and high-density models for cool- and warm-season, respectively. The spherically distributed atmospheric distance is traced along the slant path, and the resultant directional shielding by Martian atmosphere is coupled with Curiosity vehicle for dose estimates. We present predictions of dose rate and comparison to the RAD measurements. The simulation agrees to within +/- 20% with the RAD measurements showing clearly the variation of dose rate by heliospheric conditions, and presenting the sensitivity of dose rate by atmospheric pressure

  10. Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

    PubMed Central

    Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min; Lapidus, Alla; Copeland, Alex; Kim, Edwin; Land, Miriam; Mavromatis, Konstantinos; Pitluck, Samuel; Richardson, Paul M.; Detter, Chris; Brettin, Thomas; Saunders, Elizabeth; Lai, Barry; Ravel, Bruce; Kemner, Kenneth M.; Wolf, Yuri I.; Sorokin, Alexander; Gerasimova, Anna V.; Gelfand, Mikhail S.; Fredrickson, James K.; Koonin, Eugene V.; Daly, Michael J.

    2007-01-01

    Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to

  11. Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

    SciTech Connect

    Makarova, Kira S.; Omelchenko, Marina; Gaidamakova, Elena; Matrosova, Vera; Vasilenko, Alexander; Zhai, Min; Lapidus, Alla L.; Copeland, A; Kim, Edwin; Land, Miriam L; Mavromatis, K; Pitluck, Samual; Richardson, P M; Detter, J. Chris; Brettin, Tom; Saunders, Elizabeth H; Lai, Barry; Ravel, Bruce; Kemner, Kenneth M; Wolf, Yuri; Sorokin, Alexei; Gerasimova, Anna; Gelfand, Mikhail; Fredrickson, James K; Koonin, Eugene; Daly, Michael

    2007-01-01

    Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at its optimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to

  12. Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

    SciTech Connect

    Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min; Lapidus, Alla; Copeland, Alex; Kim, Edwin; Land, Miriam; Mavrommatis, Konstantinos; Pitluck, Samuel; Richardson, Paul M.; Detter, Chris; Brettin, Thomas; Saunders, Elizabeth; Lai, Barry; Ravel, Bruce; Kemner, Kenneth M.; Wolf, Yuri I.; Sorokin, Alexander; Gerasimova, Anna V.; Gelfand, Mikhail S.; Fredrickson, James K.; Koonin, Eugene V.; Daly, Michael J.

    2007-07-24

    Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at itsoptimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to

  13. The oncogenic action of ionizing radiation on rat skin

    SciTech Connect

    Burns, F.J.; Garte, S.J.

    1992-01-01

    The multistage theory of carcinogenesis specifies that cells progress to cancer through a series of discrete, irreversible genetic alterations, but data on radiation-induced cancer incidence in rat skin suggests that an intermediate repairable alteration may occur. Data are presented on cancer induction in rat skin exposed to an electron beam (LET=0.34 keV/[mu]), a neon ion beam (LET=45) or an argon ion beam (LET=125). The rats were observed for tumors at least 78 weeks with squamous and basal cell carcinomas observed. The total cancer yield was fitted by the quadratic equation, and the equation parameters were estimated by linear regression for each type of radiation. Analysis of the DNA from the electron-induced carcinomas indicated that K-ras and/or c-myc oncogenes were activated. In situ hybridization indicated that the cancers contain subpopulations of cells with differing amounts of c-myc and H-ras amplification. The results are consistent with the idea that ionizing radiation produces stable, carcinogenically relevant lesions via 2 repairable events at low LET and via a non-repairable linked event pathway at high LET; either pathway may advance the cell by 1 stage. The proliferative response of rat epidermis following exposure to ionizing radiation was quantified by injection of [sup 14]C-thymidine. The return of these cells to S-phase a second time was detected by a second label ([sup 3]H). When the labeled cells were in G1-phase, the dorsal skin was irradiated with X-rays. All labeling indices were determined. The [sup 14]C labeling index was constant and unaffected by the radiation. The proportion of all cells entering S-phase averaged 3.5% at 18 hr and increased after 44, 52 and 75 hr to average levels of 11.8%, 5. 3%, and 6.6% at 0, 10 and 25 Gy respectively. The proportion of S-phase cells labeled with [sup 14]C increased after 42 hr and remained relatively constant thereafter.

  14. Radiation sterilization of medical devices. Effects of ionizing radiation on ultra-high molecular-weight polyethylene

    NASA Astrophysics Data System (ADS)

    Buchalla, R.; Schüttler, C.; Bögl, K. W.

    1995-02-01

    Sterilization by ionizing radiation has become, next to ethylene oxide treament, the most important "cold" sterilization process for medical devices made from plastics. The effects of ionizing radiation on the most important polymer for medical devices, ultra-high molecular-weight polyethylene, are briefly described in this review.

  15. Organic semiconducting single crystals as solid-state sensors for ionizing radiation.

    PubMed

    Fraboni, Beatrice; Ciavatti, Andrea; Basiricò, Laura; Fraleoni-Morgera, Alessandro

    2014-01-01

    So far, organic semiconductors have been mainly proposed as detectors for ionizing radiation in the indirect conversion approach, i.e. as scintillators, which convert ionizing radiation into visible photons, or as photodiodes, which detect visible photons coming from a scintillator and convert them into an electrical signal. The direct conversion of ionizing radiation into an electrical signal within the same device is a more effective process than indirect conversion, since it improves the signal-to-noise ratio and it reduces the device response time. We report here the use of Organic Semiconducting Single Crystals (OSSCs) as intrinsic direct ionizing radiation detectors, thanks to their stability, good transport properties and large interaction volume. Ionizing radiation X-ray detectors, based on low-cost solution-grown OSSCs, are here shown to operate at room temperature, providing a stable linear response with increasing dose rate in the ambient atmosphere and in high radiation environments. PMID:25485676

  16. Ionizing radiation risks to satellite power systems (SPS) workers

    SciTech Connect

    Lyman, J.T.; Ainsworth, E.J.; Alpen, E.L.; Bond, V.; Curtis, S.B.; Fry, R.J.M.; Jackson, K.L.; Nachtwey, S.; Sondhaus, C.; Tobias, C.A.; Fabrikant, J.I.

    1980-11-01

    The radiation risks to the health of workers who will construct and maintain solar power satellites in the space environment were examined. For ionizing radiation, the major concern will be late or delayed health effects, particularly the increased risk of radiation-induced cancer. The estimated lifetime risk for cancer is 0.8 to 5.0 excess deaths per 10,000 workers per rad of exposure. Thus, for example, in 10,000 workers who completed ten missions with an exposure of 40 rem per mission, 320 to 2000 additional deaths in excess of the 1640 deaths from normally occurring cancer, would be expected. These estimates would indicate a 20 to 120% increase in cancer deaths in the worker-population. The wide range in these estimates stems from the choice of the risk-projection model and the dose-response relationsip. The choice between a linear and a linear-quadratic dose-response model may alter the risk estimate by a factor of about two. The method of analysis (e.g., relative vs absolute risk model) can alter the risk estimate by an additional factor of three. Choosing different age and sex distributions can further change the estimate by another factor of up to three. The potential genetic consequences could be of significance, but at the present time, sufficient information on the age and sex distribution of the worker population is lacking for precise estimation of risk. The potential teratogenic consequences resulting from radiation are considered significant. Radiation exposure of a pregnant worker could result in developmental abnormalities.

  17. What happens when spins meet for ionizing radiation dosimetry?

    NASA Astrophysics Data System (ADS)

    Pavoni, Juliana F.; Neves-Junior, Wellington F. P.; Baffa, Oswaldo

    2016-07-01

    Electron spin resonance (ESR) and magnetic resonance imaging (MRI) can be used to measure radiation dose deposited in different milieu through its effects. Radiation can break chemical bonds and if they produce stable free radicals, ESR can measure their concentration through their spins and a dose can be inferred. Ionizing radiation can also promote polymerization and in this case proton relaxation times can be measured and an image weighed by T2 can be produced giving spatial information about dose. A review of the basics of these applications is presented concluding with an end-to-end test using a composite Gel-Alanine phantom to validate 3-dimensionally dose distribution delivered in a simulation of Volume Modulated Arch Therapy on the simultaneous treatment of multiple brain metastases. The results obtained with the gel and alanine dosimeters are consistent with the expected by the treatment planning system, showing the potential of this multidosimetric approach and validating dosimetrically the multiple brain metastases treatment using VMAT.

  18. Response of ionization chamber based pocket dosimeter to beta radiation.

    PubMed

    Kumar, Munish; Gupta, Anil; Pradhan, S M; Bakshi, A K; Chougaonkar, M P; Babu, D A R

    2013-12-01

    Quantitative estimate of the response of ionization chamber based pocket dosimeters (DRDs) to various beta sources was performed. It has been established that the ionization chamber based pocket dosimeters do not respond to beta particles having energy (Emax)<1 MeV and same was verified using (147)Pm, (85)Kr and (204)Tl beta sources. However, for beta particles having energy >1 MeV, the DRDs exhibit measureable response and the values are ~8%, ~14% and ~27% per mSv for natural uranium, (90)Sr/(90)Y and (106)Ru/(106)Rh beta sources respectively. As the energy of the beta particles increases, the response also increases. The response of DRDs to beta particles having energy>1 MeV arises due to the fact that the thickness of the chamber walls is less than the maximum range of beta particles. This may also be one of the reasons for disparity between doses measured with passive/legal dosimeters (TLDs) and DRDs in those situations in which radiation workers are exposed to mixed field of gamma photons and beta particles especially at uranium processing plants, nuclear (power and research) reactors, waste management facilities and fuel reprocessing plants etc. The paper provides the reason (technical) for disparity between the doses recorded by TLDs and DRDs in mixed field of photons and beta particles. PMID:23978508

  19. Age and hormonal status as determinants of cataractogenesis induced by ionizing radiation. II. Sparsely ionizing (low-LET) radiation.

    PubMed

    Dynlacht, Joseph R; Valluri, Shailaja; Garrett, Joy; Nees, Jessica; Caperell-Grant, Andrea; DesRosiers, Colleen; Bigsby, Robert M

    2012-10-01

    Age at the time of exposure to sparsely ionizing radiation has been established as a key determinant of radiation cataractogenesis. However, while some reports suggest that the lenses of the young are hypersensitive, data from older studies are often conflicting and somewhat difficult to interpret when the radioresponse of young lenses is compared to that of adult lenses. Moreover, the mechanism of the age-response function for radiation cataractogenesis has yet to be identified. Since steroid sex hormones, notably estradiol, appear to play a role in age-related cataractogenesis, we hypothesized that the age response for radiation cataractogenesis could be dictated by estradiol status. We recently showed that exposure to high-linear energy transfer (LET) radiation resulted in a reduced latent period for, and enhanced progression of cataracts in rats that were 1 year old at the time of exposure compared to those that were 56 days old. However, the enhanced sensitivity of older lenses compared to younger lenses was independent of estradiol status. In the current study, we found that for 1-year-old rats exposed to 10 Gy of low-LET (60)Co γ rays, the rate of increase in the development of posterior and anterior subcapsular cataracts was higher in older ovary-intact rats compared to young rats. However, cataracts were detected much earlier in ovary-intact 56-day-old rats compared to 1-year-old rats, regardless of their treatment groups (ovary-intact, ovariectomized, or ovariectomized and implanted with capsules containing estradiol). Thus, despite a consistent estradiol response (potentiating effect of estrogen) within a given age group, the differences between the radiation response of old and young lenses cannot be accounted for solely by estradiol status. PMID:22880623

  20. Study of ionizing radiation on the properties of polyamide 6 with fiberglass reinforcement

    NASA Astrophysics Data System (ADS)

    Pinto, Clovis; Silva, Leonardo G. Andrade e.

    2007-11-01

    The use of polymers reinforced with fiberglass is becoming more and more common in the switches for household industries. These compounds perform a good tension resistance to the impact and the humidity absorption being used at the present time and also are in the automobile industry in parts underneath the hood, especially in the radiator frames. The aim of this work is to study the effect of ionizing radiation on the properties of polyamide 6 with fiberglass reinforcement and undergone to different irradiation doses. Samples were prepared and irradiated on JOB 188 accelerator with an electron beam energy of 1.5 MeV in air with different doses and a dose rate of 27.99 kGy/h. Afterward, the properties of the non-irradiated and irradiated polyamide 6 with fiberglass reinforcement were evaluated.

  1. Neurologic sequelae of methotrexate and ionizing radiation: a new classification

    SciTech Connect

    Bleyer, W.A.

    1981-01-01

    Therapy for prevention of central nervous system (CNS) leukemia has had a dramatic effect on disease-free survival in children with acute lymphoblastic leukemia (ALL). Now, a majority of children may be in complete remission indefinitely, having completed therapy years ago. Unfortunately, some of these long-term survivors have residual neurologic dysfunction, varying in severity from the not uncommon occurrence of mild intellectual deficit to the fortunately rare instance of debilitating leukoencephalopathy. To help identify inciting factors and ultimately render CNS prophylaxis less neurotoxic, this article attempts to categorize the types of neurotoxicities reported in patients treated with methotrexate (MTX) and ionizing radiation. A variety of clinical syndromes are described and related temporally to these treatment modalities. Analyzed in this way, combinations including CNS irradiation appear to be the most neurotoxic. The safest methods are the single modalities, of which high-dose iv MTX may be the least neurotoxic.

  2. Coupling the emission of ionizing radiation and Lyman alpha

    NASA Astrophysics Data System (ADS)

    Scarlata, Claudia; Hayes, Matthew; Miller, Brendan P.; Pushnig, Johannes; Jansson, Gustav

    2016-01-01

    The class of objects that reionized the intergalactic hydrogen remains an observational and theoretical challenge. Recently, the shape of the Lyman-alpha (Lya) emission line profile has been proposed as a way to pre-select Lyman Continuum (LyC) leaking galaxies. We present results of deep spectroscopic observations obtained with the Cosmic Origin Spectrograph on the HST of a sample of 4 Lya-emitting galaxies at z~0.3, chosen to be candidate LyC leaking galaxies, on the grounds of blueshifted peaks of Lya emission/symmetric extended Lya wings. We do not detect ionizing radiation escaping from these objects, with upper 3sigma limits on the absolute escape fraction of LyC photons between 14 and 2%.

  3. [Role of the practitioner after accidents related to ionizing radiation].

    PubMed

    Vrousos, C; Kolodié, H; Gallin-Martel, C; Pons, H

    1995-03-15

    Accidents due to ionizing radiations can be nuclear accidents, concerning a large part of the population, or radiological accidents which may, at higher doses, irradiate a limited number of persons. In case of nuclear accident, radioactive rejections lead to an irradiation and/or a contamination, and induce the "préfet" to take public health measures. According to the dose possibly received by the population, measures can be the continuation of normal life, confinement, distribution of stable iodine, restriction of certain food consummation, evacuation being the ultimate measure. General practitioner will be an important actor in the information of the populations. When a radiological accident occurs, the management will depend on the type of accident and the dose emitted. This treatment of medico-surgical emergency is an absolute priority, if traumatic lesions are associated, on nuclear risk, especially when prognosis for life is involved. Lesions associated to radiolesions worsen the prognosis. PMID:7754325

  4. Ionizing radiation-induced mutation of human cells with different DNA repair capacities

    NASA Astrophysics Data System (ADS)

    Amundson, S. A.; Chen, D. J.

    We have observed significant differences in the response to ionizing radiation of two closely related human cell lines, and now compare the effects on these lines of both low and intermediate LET radiation. Compared to TK6, WTK1 has an enhanced X-ray survival, and is also more resistant to cell killing by alpha-particles. The hprt locus is more mutable in WTK1 than in TK6 by both X-rays and alpha-particles. WTK1 is also more mutable by alpha-particles than by X-rays at the hprt locus. X-ray-induced mutation at the heterozygous tk locus in WTK1 is about 25 fold higher than in TK6, while alpha-particle-induced mutation is nearly 50 fold higher at this locus. Also, the slowly growing tk- mutants, which comprise the majority of spontaneous and X-ray-inducedtk - mutants of TK6, were not induced significantly by alpha-particles. Previously, we showed that TK6 has a reduced capacity for recombination compared with WTK1, and therefore, these results indicate that recombinational repair may contribute to both cell survival and mutation-induction following exposure to ionizing radiation. Such a mechanism may aid cell survival, but could also result in increased deleterious effects such as the unmasking of recessive mutations in cancer suppresser genes.

  5. Ionizing radiation-induced mutation of human cells with different DNA repair capacities

    SciTech Connect

    Amundson, S.A.; Chen, D.J.

    1994-12-31

    We have observed significant differences in the response to ionizing radiation of two closely related human cell lines, and now compare the effects on these lines of both low and intermediate LET radiation. Compared to TK6, WTK1 has an enhanced X-ray survival, and is also more resistant to cell killing by {alpha}-particles. The hprt locus is more mutable in WTK1 than in TK6 by both X-rays and {alpha}-particles. WTK1 is also more mutable by {alpha}-particles than by X-rays at the hprt locus. X-ray-induced mutation at the heterozygous tk locus in WTK1 is about 25 fold higher than in TK6, while {alpha}-particle-induced mutation is nearly 50 fold higher at this locus. Also, the slowly growing tk- mutants, which comprise the majority of spontaneous and X-ray-induced tk- mutants of TK6, were not induced significantly by {alpha}-particles. Previously, we showed that TK6 has a reduced capacity for recombination compared with WTK1, and therefore, these results indicate that recombinational repair may contribute to both cell survival and mutation-induction following exposure to ionizing radiation. Such a mechanism may aid cell survival, but could also result in increased deleterious effects such as the unmasking of recessive mutations in cancer suppresser genes.

  6. Ionizing radiation delivered by specific antibody is therapeutic against a fungal infection

    PubMed Central

    Dadachova, Ekaterina; Nakouzi, Antonio; Bryan, Ruth A.; Casadevall, Arturo

    2003-01-01

    There is an urgent need for new antimicrobial therapies to combat drug resistance, new pathogens, and the relative inefficacy of current therapy in compromised hosts. Ionizing radiation can kill microorganisms quickly and efficiently, but this modality has not been exploited as a therapeutic antimicrobial strategy. We have developed methods to target ionizing radiation to a fungal cell by labeling a specific mAb with the therapeutic radioisotopes Rhenium-188 and Bismuth-213. Radiolabeled antibody killed cells of human pathogenic fungus Cryptococcus neoformans in vitro, thus converting an antibody with no inherent antifungal activity into a microbicidal molecule. Administration of radiolabeled antibody to mice with C. neoformans infection delivered 213Bi and 188Re to the sites of infection, reduced their organ fungal burden, and significantly prolonged their survival without apparent toxicity. This study establishes the principle that targeted radiation can be used for the therapy of an infectious disease, and suggests that it may have wide applicability as an antimicrobial strategy. PMID:12930899

  7. The effects of ionizing radiation on fiber optic systems and components for use in mobile platforms

    NASA Astrophysics Data System (ADS)

    Reddy, Mahesh; Krinsky, Jeff

    1991-02-01

    Many applications for fiber optic components and systems exist in mobile platforms. Some of the mobile platforms will be expected to operate through or survive exposure to ionizing radiation. Construction of systems that can survive the required radiation environments requires special design considerations. This paper describes the effects of ionizing radiation on some fiber optic components and systems for use in mobile platforms, and an example of transient radiation test data on a prototype analog two wavelength referenced system is presented.

  8. CONSULTATION ON UPDATED METHODOLOGY FOR ESTIMATING CANCER RISKS FROM EXPOSURE TO IONIZING RADIATION

    EPA Science Inventory

    The National Academy of Sciences (NAS) expects to publish the Biological Effects of Ionizing Radiation (BEIR) committee's report (BEIR VII) on risks from ionizing radiation exposures in calendar year 2005. The committee is expected to have analyzed the most recent epidemiology f...

  9. Code of Practice for the Use of Ionizing Radiations in Secondary Schools.

    ERIC Educational Resources Information Center

    National Health and Medical Research Council, Canberra (Australia).

    The appreciation of the potential hazard of ionizing radiation led to the setting up of national, and later, international commissions for the defining of standards of protection for the occupationally exposed worker in the use of ionizing radiation. However, in the last twenty years, with the large scale development of nuclear energy, the need…

  10. Ionizing radiation: Future etiologic research and preventive strategies

    SciTech Connect

    Darby, S.C.; Inskip, P.D.

    1995-11-01

    Estimates of cancer risks following exposure to ionizing radiation traditionally have been based on the experience of populations exposed to substantial (and known) doses delivered over short periods of time. Examples include survivors of the atomic bombings at Hiroshima and Nagasaki, and persons treated with radiation for benign or malignant disease. Continued follow-up of these populations is important to determine the long-term effects of exposure in childhood, to characterize temporal patterns of excess risk for different types of cancer, and to understand better the interactions between radiation and other host and environmental factors. Studies of nuclear workers chronically exposed over a working lifetime provide data that preliminary indications are that the risks per unit dose for most cancers other than leukemia are similar to those for acute exposure. However, these results are subject to considerable uncertainty, and further information on this question is needed. Residential radon is the major source of population exposure to high-LET radiation. Current estimates of the risk of lung cancer due to residential exposure to radon and radon daughters are based on the experience of miners exposed to much higher concentrations. Data indicate that lung cancer risk among miners is inversely associated with exposure rate, and also is influenced by the presence of other lung carcinogens such as arsenic in the mine environment. Further study of populations of radon-exposed miners would be informative, particularly those exposed at below-average levels. More direct evidence on the effects of residential exposure to radon also is desirable but might be difficult to come by, as risks associated with radon levels found in most homes might be too low to be quantified accurately in epidemiological studies. 29 refs., 3 figs., 5 tabs.

  11. microRNAs in Cancer Cell Response to Ionizing Radiation

    PubMed Central

    Czochor, Jennifer R.

    2014-01-01

    Abstract Significance: microRNAs (miRNA) have been characterized as master regulators of the genome. As such, miRNAs are responsible for regulating almost every cellular pathway, including the DNA damage response (DDR) after ionizing radiation (IR). IR is a therapeutic tool that is used for the treatment of several types of cancer, yet the mechanism behind radiation response is not fully understood. Recent Advances: It has been demonstrated that IR can alter miRNA expression profiles, varying greatly from one cell type to the next. It is possible that this variation contributes to the range of tumor cell responsiveness that is observed after radiotherapy, especially considering the extensive role for miRNAs in regulating the DDR. In addition, individual miRNAs or miRNA families have been shown to play a multifaceted role in the DDR, regulating multiple members in a single pathway. Critical Issues: In this review, we will discuss the effects of radiation on miRNA expression as well as explore the function of miRNAs in regulating the cellular response to radiation-induced damage. We will discuss the importance of miRNA regulation at each stage of the DDR, including signal transduction, DNA damage sensing, cell cycle checkpoint activation, DNA double-strand break repair, and apoptosis. We will focus on emphasizing the importance of a single miRNA targeting several mediators within a pathway. Future Directions: miRNAs will continue to emerge as critical regulators of the DDR. Understanding the role of miRNAs in the response to IR will provide insights for improving the current standard therapy. Antioxid. Redox Signal. 21, 293–312. PMID:24206455

  12. Pluripotent stem cells and DNA damage response to ionizing radiations

    PubMed Central

    Mujoo, Kalpana; Butler, E. Brian; Pandita, Raj K.; Hunt, Clayton R.; Pandita, Tej K.

    2016-01-01

    Pluripotent stem cells (PSCs) hold great promise in regenerative medicine, disease modeling, functional genomics, toxicological studies and cell-based therapeutics due to their unique characteristics of self-renewal and pluripotency. Novel methods for generation of pluripotent stem cells and their differentiation to the specialized cell types such as neuronal cells, myocardial cells, hepatocytes, and beta cells of the pancreas and many other cells of the body are constantly being refined. Pluripotent stem cell derived differentiated cells, including neuronal cells or cardiac cells are ideal for stem cell transplantation as autologous or allogeneic cells from healthy donors due to their minimum risks of rejection. DNA damage induced by ionizing radiation (IR), ultraviolet (UV) light, genotoxic stress, and other intrinsic and extrinsic factors trigger a series of biochemical reactions termed as DNA damage response (DDR). In order to maintain genomic stability, and avoid transmission of mutations into progenitors cells, stem cells have robust DNA damage response signaling – a contrast to somatic cells. Stem cell transplantation may over come the late effects related to radiation. This review will particularly focus on differential DNA damage response between stem cells and derived differentiated cells and the possible pathways that determine such differences. PMID:27332952

  13. Ionizing radiation induces human intercellular adhesion molecule-1 in vitro.

    PubMed

    Behrends, U; Peter, R U; Hintermeier-Knabe, R; Eissner, G; Holler, E; Bornkamm, G W; Caughman, S W; Degitz, K

    1994-11-01

    Intercellular adhesion molecule-1 (ICAM-1) plays a central role in various inflammatory reactions and its expression is readily induced by inflammatory stimuli such as cytokines or ultraviolet irradiation. We have investigated the effect of ionizing radiation (IR) on human ICAM-1 expression in human cell lines and skin cultures. ICAM-1 mRNA levels in HL60, HaCaT, and HeLa cells were elevated at 3-6 h after irradiation and increased with doses from 10-40 Gy. The rapid induction of ICAM-1 occurred at the level of transcription, was independent of de novo protein synthesis, and did not involve autocrine stimuli including tumor necrosis factor-alpha and interleukin-1. IR also induced ICAM-1 cell surface expression within 24 h. Immunohistologic analysis of cultured human split skin revealed ICAM-1 upregulation on epidermal keratinocytes and dermal microvascular endothelial cells 24 h after exposure to 6 Gy. In conclusion, we propose ICAM-1 as an important radiation-induced enhancer of immunologic cell adhesion, which contributes to inflammatory reactions after local and total body irradiation. PMID:7963663

  14. Cognitive function and prenatal exposure to ionizing radiation.

    PubMed

    Schull, W J; Otake, M

    1999-04-01

    It is clear from the many studies of the prenatally exposed survivors of the atomic bombing of Hiroshima and Nagasaki that exposure to ionizing radiation during gestation has harmful effects on the developing human brain, particularly if that exposure occurs at critical stages in the development of the neocortex. Data on a variety of measures of cognitive function, including the occurrence of severe mental retardation as well as variation in the intelligence quotient (IQ) and school performance, show significant effects on those survivors exposed 8-15 weeks and 16-25 weeks after ovulation. Studies of seizures, primarily those without known precipitating cause, also exhibit a radiation effect on those individuals exposed in the first 16 weeks after ovulation. The cellular and molecular events that subtend these abnormalities are still largely unknown although some progress toward an understanding has occurred. For example, magnetic resonance imaging of the brain of some of the mentally retarded survivors has revealed a large region of abnormally situated gray matter, suggesting an abnormality in neuronal migration, but cell killing could also contribute importantly to the effects on cognitive function that have been seen. The retardation of growth in stature observed in individuals exposed in the first and second trimesters of pregnancy suggests that the development of an atypically small head size, without conspicuously impaired cognitive function, may reflect a generalized retardation of growth. PMID:10331523

  15. Purification of sulfide-alkali effluent with the aid of ionizing radiation. [Gamma radiation

    SciTech Connect

    Petryaev, E.P.; Gerasimovich, O.A.; Kovalevskaya, A.M.; Plyuto, I.Ch.; Shlyk, V.G.

    1984-03-01

    The treatment of sulfide-alkali effluent under the effect of ionizing radiation was investigated. The source was an LMB-..gamma..-1M ..gamma..-apparatus with /sup 137/Cs source. The dose rate was 52 rad/s. Irradiation was done in glass ampules and in vessels allowing bubbling with air and irradiation to be carried out at the same time. 7 references, 1 figure, 1 table.

  16. Therapeutic Implications for Overcoming Radiation Resistance in Cancer Therapy

    PubMed Central

    Kim, Byeong Mo; Hong, Yunkyung; Lee, Seunghoon; Liu, Pengda; Lim, Ji Hong; Lee, Yong Heon; Lee, Tae Ho; Chang, Kyu Tae; Hong, Yonggeun

    2015-01-01

    Ionizing radiation (IR), such as X-rays and gamma (γ)-rays, mediates various forms of cancer cell death such as apoptosis, necrosis, autophagy, mitotic catastrophe, and senescence. Among them, apoptosis and mitotic catastrophe are the main mechanisms of IR action. DNA damage and genomic instability contribute to IR-induced cancer cell death. Although IR therapy may be curative in a number of cancer types, the resistance of cancer cells to radiation remains a major therapeutic problem. In this review, we describe the morphological and molecular aspects of various IR-induced types of cell death. We also discuss cytogenetic variations representative of IR-induced DNA damage and genomic instability. Most importantly, we focus on several pathways and their associated marker proteins responsible for cancer resistance and its therapeutic implications in terms of cancer cell death of various types and characteristics. Finally, we propose radiation-sensitization strategies, such as the modification of fractionation, inflammation, and hypoxia and the combined treatment, that can counteract the resistance of tumors to IR. PMID:26569225

  17. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    DOE PAGESBeta

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; et al

    2014-10-22

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initiallymore » improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Finally, understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.« less

  18. Cardiovascular risks associated with low dose ionizing particle radiation.

    PubMed

    Yan, Xinhua; Sasi, Sharath P; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A

    2014-01-01

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton ((1)H; 0.5 Gy, 1 GeV) and iron ion ((56)Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in (56)Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, (56)Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy. PMID:25337914

  19. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    SciTech Connect

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F.; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A.

    2014-10-22

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Finally, understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy.

  20. Status of LDEF ionizing radiation measurements and analysis

    NASA Technical Reports Server (NTRS)

    Parnell, Thomas A.

    1993-01-01

    At this symposium significant new data and analyses were reported in cosmic ray research, radiation dosimetry, induced radioactivity, and radiation environment modeling. Measurements of induced radioactivity and absorbed dose are nearly complete, but much analysis and modeling remains. Measurements and analyses of passive nuclear track detectors (PNTD), used to derive the cosmic ray composition and spectra, and linear energy transfer (LET) spectra, are only a few percent complete, but important results have already emerged. As one might expect at this stage of the research, some of the new information has produced questions rather than answers. Low-energy heavy nuclei detected by two experiments are not compatible with known solar or cosmic components. Various data sets on absorbed dose are not consistent, and a new trapped proton environment model does not match the absorbed dose data. A search for cosmogenic nuclei other than Be-7 on Long Duration Exposure Facility (LDEF) surfaces has produced an unexpected result, and some activation data relating to neutrons is not yet understood. Most of these issues will be resolved by the analysis of further experiment data, calibrations, or the application of the large LDEF data set that offers alternate data or analysis techniques bearing on the same problem. The scope of the papers at this symposium defy a compact technical summary. I have attempted to group the new information that I noted into the following groups: induced radioactivity; absorbed dose measurements; LET spectra and heavy ion dosimetry; environment modeling and three dimensional shielding effects; cosmogenic nuclei; and cosmic rays and other heavy ions. The papers generally are expository and have excellent illustrations, and I refer to their figures rather than reproduce them here. The general program and objectives of ionizing radiation measurements and analyses on LDEF has been described previously.

  1. Cardiovascular Risks Associated with Low Dose Ionizing Particle Radiation

    PubMed Central

    Yan, Xinhua; Sasi, Sharath P.; Gee, Hannah; Lee, JuYong; Yang, Yongyao; Mehrzad, Raman; Onufrak, Jillian; Song, Jin; Enderling, Heiko; Agarwal, Akhil; Rahimi, Layla; Morgan, James; Wilson, Paul F.; Carrozza, Joseph; Walsh, Kenneth; Kishore, Raj; Goukassian, David A.

    2014-01-01

    Previous epidemiologic data demonstrate that cardiovascular (CV) morbidity and mortality may occur decades after ionizing radiation exposure. With increased use of proton and carbon ion radiotherapy and concerns about space radiation exposures to astronauts on future long-duration exploration-type missions, the long-term effects and risks of low-dose charged particle irradiation on the CV system must be better appreciated. Here we report on the long-term effects of whole-body proton (1H; 0.5 Gy, 1 GeV) and iron ion (56Fe; 0.15 Gy, 1GeV/nucleon) irradiation with and without an acute myocardial ischemia (AMI) event in mice. We show that cardiac function of proton-irradiated mice initially improves at 1 month but declines by 10 months post-irradiation. In AMI-induced mice, prior proton irradiation improved cardiac function restoration and enhanced cardiac remodeling. This was associated with increased pro-survival gene expression in cardiac tissues. In contrast, cardiac function was significantly declined in 56Fe ion-irradiated mice at 1 and 3 months but recovered at 10 months. In addition, 56Fe ion-irradiation led to poorer cardiac function and more adverse remodeling in AMI-induced mice, and was associated with decreased angiogenesis and pro-survival factors in cardiac tissues at any time point examined up to 10 months. This is the first study reporting CV effects following low dose proton and iron ion irradiation during normal aging and post-AMI. Understanding the biological effects of charged particle radiation qualities on the CV system is necessary both for the mitigation of space exploration CV risks and for understanding of long-term CV effects following charged particle radiotherapy. PMID:25337914

  2. Responses of human embryonic stem cells and their differentiated progeny to ionizing radiation

    SciTech Connect

    Zou, Ying; Zhang, Ningzhe; Ellerby, Lisa M.; Davalos, Albert R.; Zeng, Xianmin; Campisi, Judith; Desprez, Pierre-Yves

    2012-09-14

    Highlights: Black-Right-Pointing-Pointer hESCs and their progeny, NSCs and neurons, were exposed to ionizing radiation. Black-Right-Pointing-Pointer Upon irradiation, most hESCs died within 5-7 h. Black-Right-Pointing-Pointer Surviving NSCs underwent senescence and displayed features of astrocytes. Black-Right-Pointing-Pointer Surviving NSCs did not display the secretory phenotype expressed by pure astrocytes. Black-Right-Pointing-Pointer This study is to better understand the stress-responses of hESCs and their progeny. -- Abstract: Human embryonic stem cells (hESCs) hold promise for the treatment of many human pathologies. For example, hESCs and the neuronal stem cells (NSCs) and neurons derived from them have significant potential as transplantation therapies for a variety of neurodegenerative diseases. Two concerns about the use of hESCs and their differentiated derivatives are their ability to function and their ability to resist neoplastic transformation in response to stresses that inevitably arise during their preparation for transplantation. To begin to understand how these cells handle genotoxic stress, we examined the responses of hESCs and derived NSCs and neurons to ionizing radiation (IR). Undifferentiated hESCs were extremely sensitive to IR, with nearly all the cells undergoing cell death within 5-7 h. NSCs and neurons were substantially more resistant to IR, with neurons showing the most resistant. Of interest, NSCs that survived IR underwent cellular senescence and acquired astrocytic characteristics. Unlike IR-treated astrocytes, however, the NSC-derived astrocytic cells that survived IR did not display the typical pro-inflammatory, pro-carcinogenic senescence-associated secretory phenotype. These findings suggest distinct genotoxic stress-responses of hESCs and derived NSC and neuronal populations, and suggest that damaged NSCs, while failing to function, may not cause local inflammation.

  3. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1981-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiation heating of probes entering the hydrogen helium atmospere of the major planets was investigated. At the present time, there is disagreement as to whether the radiative flux increases or decreases relative to its equilibrium value when finite rate ionization is considered. Leibowitz and Kuo content that the finite rate ionization in the hydrogen gas just behind the shock wave reduces the radiative flux to the probe, whereas Tiwari and Szema predict that it increases the radiative flux. The radiation modeling used in the calculations of both pairs of these investigators was reviewed. It is concluded that finite rate ionization in the inviscid region of the shock layer should reduce the cold wall radiative heating below the values predicted by equilibrium chemistry assumptions.

  4. Calculation of H2-He Flow with Nonequilibrium Ionization and Radiation: an Interim Report

    NASA Technical Reports Server (NTRS)

    Furudate, Michiko; Chang, Keun-Shik

    2005-01-01

    The nonequilibrium ionization process in hydrogen-helium mixture behind a strong shock wave is studied numerically using the detailed ionization rate model developed recently by Park which accounts for emission and absorption of Lyman lines. The study finds that, once the avalanche ionization is started, the Lyman line is self-absorbed. The intensity variation of the radiation at 5145 Angstroms found by Leibowitz in a shock tube experiment can be numerically reproduced by assuming that ionization behind the shock wave prior to the onset of avalanche ionization is 1.3%. Because 1.3% initial ionization is highly unlikely, Leibowitz s experimental data is deemed questionable. By varying the initial electron density value in the calculation, the calculated ionization equilibration time is shown to increase approximately as inverse square-root of the initial electron density value. The true ionization equilibration time is most likely much longer than the value found by Leibowitz.

  5. Ionizing Radiation-Induced Responses in Human Cells with Differing TP53 Status

    PubMed Central

    Mirzayans, Razmik; Andrais, Bonnie; Scott, April; Wang, Ying W.; Murray, David

    2013-01-01

    Ionizing radiation triggers diverse responses in human cells encompassing apoptosis, necrosis, stress-induced premature senescence (SIPS), autophagy, and endopolyploidy (e.g., multinucleation). Most of these responses result in loss of colony-forming ability in the clonogenic survival assay. However, not all modes of so-called clonogenic cell “death” are necessarily advantageous for therapeutic outcome in cancer radiotherapy. For example, the crosstalk between SIPS and autophagy is considered to influence the capacity of the tumor cells to maintain a prolonged state of growth inhibition that unfortunately can be succeeded by tumor regrowth and disease recurrence. Likewise, endopolyploid giant cells are able to segregate into near diploid descendants that continue mitotic activities. Herein we review the current knowledge on the roles that the p53 and p21WAF1 tumor suppressors play in determining the fate of human fibroblasts (normal and Li-Fraumeni syndrome) and solid tumor-derived cells after exposure to ionizing radiation. In addition, we discuss the important role of WIP1, a p53-regulated oncogene, in the temporal regulation of the DNA damage response and its contribution to p53 dynamics post-irradiation. This article highlights the complexity of the DNA damage response and provides an impetus for rethinking the nature of cancer cell resistance to therapeutic agents. PMID:24232458

  6. Highly Elliptical Orbits for Arctic observations: Assessment of ionizing radiation

    NASA Astrophysics Data System (ADS)

    Trichtchenko, L. D.; Nikitina, L. V.; Trishchenko, A. P.; Garand, L.

    2014-12-01

    The ionizing radiation environment was analyzed for a variety of potential Highly Elliptical Orbits (HEOs) with orbital periods ranging from 6 h to 24 h suitable to continuously monitor the Arctic region. Several models available from the ESA Space Environment Information System (SPENVIS) online tool were employed, including the new-generation AE9/AP9 model for trapped radiation. Results showed that the Total Ionizing Dose (TID) has a well-pronounced local minimum for the 14-h orbit, which is nearly identical to the overall minimum observed for the longest orbital period (24 h). The thickness of slab aluminum shielding required to keep the annual TID below 10, 5 and 3.33 krad (i.e. 150, 75 and 50 krad for 15 years of mission duration) for a 14-h orbit is 2.1, 2.7 and 3.1 mm respectively. The 16-h orbit requires an additional 0.5 mm of aluminum to achieve the same results, while the 24-h orbit requires less shielding in the order of 0.2-0.3 mm. Comparison between the AE8/AP8 and AE9/AP9 models was conducted for all selected orbits. Results demonstrated that differences ranged from -70% to +170% depending on orbit geometry. The vulnerability to the Single Event Effect (SEE) was compared for all orbits by modeling the Linear Energy Transfer (LET) for long-term conditions and for the 5 min “worst case” scenario. The analysis showed no preference among orbits with periods longer than 15 h, and in order to keep the 14-h orbit at the same level, the shielding should be increased by ∼33% or approximately by 1 mm. To keep the Single Event Upset (SEU) rate produced by the “worst case” event at the same order of magnitude as for the “statistical” long-term case, the thickness of aluminum should be as high as 22 mm. The overall conclusion from a space environment point of view is that all HEO orbits with periods equal to or longer than 14 h can be regarded as good candidates for operational missions. Therefore, selection of orbit should be based on other criteria

  7. The Inhibitory Effects of Low-Dose Ionizing Radiation in IgE-Mediated Allergic Responses

    PubMed Central

    Nam, Seon Young; Yang, Kwang Hee; Kim, Cha Soon; Lee, In Kyung; Kim, Ji Young

    2015-01-01

    Ionizing radiation has different biological effects according to dose and dose rate. In particular, the biological effect of low-dose radiation is unclear. Low-dose whole-body gamma irradiation activates immune responses in several ways. However, the effects and mechanism of low-dose radiation on allergic responses remain poorly understood. Previously, we reported that low-dose ionizing radiation inhibits mediator release in IgE-mediated RBL-2H3 mast cell activation. In this study, to have any physiological relevance, we investigated whether low-dose radiation inhibits allergic responses in activated human mast cells (HMC-1(5C6) and LAD2 cells), mouse models of passive cutaneous anaphylaxis and the late-phase cutaneous response. High-dose radiation induced cell death, but low-dose ionizing radiation of <0.5 Gy did not induce mast cell death. Low-dose ionizing radiation that did not induce cell death significantly suppressed mediator release from human mast cells (HMC-1(5C6) and LAD2 cells) that were activated by antigen-antibody reaction. To determine the inhibitory mechanism of mediator released by low-dose ionizing radiation, we examined the phosphorylation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, and protein kinase C, as well as the intracellular free Ca2+ concentration ([Ca2+]i). The phosphorylation of signaling molecules and [Ca2+]i following stimulation of FcεRI receptors was inhibited by low dose ionizing radiation. In agreement with its in vitro effect, ionizing radiation also significantly inhibited inflammatory cells infiltration, cytokine mRNA expression (TNF-α, IL-4, IL-13), and symptoms of passive cutaneous anaphylaxis reaction and the late-phase cutaneous response in anti-dinitrophenyl IgE-sensitized mice. These results indicate that ionizing radiation inhibits both mast cell-mediated immediate- and delayed-type allergic reactions in vivo and in vitro. PMID:26317642

  8. The Inhibitory Effects of Low-Dose Ionizing Radiation in IgE-Mediated Allergic Responses.

    PubMed

    Joo, Hae Mi; Kang, Su Jin; Nam, Seon Young; Yang, Kwang Hee; Kim, Cha Soon; Lee, In Kyung; Kim, Ji Young

    2015-01-01

    Ionizing radiation has different biological effects according to dose and dose rate. In particular, the biological effect of low-dose radiation is unclear. Low-dose whole-body gamma irradiation activates immune responses in several ways. However, the effects and mechanism of low-dose radiation on allergic responses remain poorly understood. Previously, we reported that low-dose ionizing radiation inhibits mediator release in IgE-mediated RBL-2H3 mast cell activation. In this study, to have any physiological relevance, we investigated whether low-dose radiation inhibits allergic responses in activated human mast cells (HMC-1(5C6) and LAD2 cells), mouse models of passive cutaneous anaphylaxis and the late-phase cutaneous response. High-dose radiation induced cell death, but low-dose ionizing radiation of <0.5 Gy did not induce mast cell death. Low-dose ionizing radiation that did not induce cell death significantly suppressed mediator release from human mast cells (HMC-1(5C6) and LAD2 cells) that were activated by antigen-antibody reaction. To determine the inhibitory mechanism of mediator released by low-dose ionizing radiation, we examined the phosphorylation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, and protein kinase C, as well as the intracellular free Ca2+ concentration ([Ca2+]i). The phosphorylation of signaling molecules and [Ca2+]i following stimulation of FcεRI receptors was inhibited by low dose ionizing radiation. In agreement with its in vitro effect, ionizing radiation also significantly inhibited inflammatory cells infiltration, cytokine mRNA expression (TNF-α, IL-4, IL-13), and symptoms of passive cutaneous anaphylaxis reaction and the late-phase cutaneous response in anti-dinitrophenyl IgE-sensitized mice. These results indicate that ionizing radiation inhibits both mast cell-mediated immediate- and delayed-type allergic reactions in vivo and in vitro. PMID:26317642

  9. Changes induced in spice paprika powder by treatment with ionizing radiation and saturated steam

    NASA Astrophysics Data System (ADS)

    Kispéter, J.; Bajúsz-Kabók, K.; Fekete, M.; Szabó, G.; Fodor, E.; Páli, T.

    2003-12-01

    The changes in spice paprika powder induced by ionizing radiation, saturated steam (SS) and their combination were studied as a function of the absorbed radiation dose and the storage time. The SS treatment lead to a decrease in color content (lightening) after 12 weeks of storage, together with the persistence of free radicals and viscosity changes for a longer period. The results suggest that ionizing radiation is a more advantageous method as concerns preservation of the quality of spice paprika.

  10. Age and hormonal status as determinants of cataractogenesis induced by ionizing radiation. I. Densely ionizing (high-LET) radiation.

    PubMed

    Dynlacht, Joseph R; Valluri, Shailaja; Garrett, Joy; Mendonca, Marc S; Lopez, Jennifer T; Caperell-Grant, Andrea; Bigsby, Robert M

    2011-01-01

    Astronauts participating in extended lunar missions or the projected mission to Mars would likely be exposed to significant doses of high-linear energy transfer (LET) heavy energetic charged (HZE) particles. Exposure to even relatively low doses of such space radiation may result in a reduced latent period for and an increased incidence of lens opacification. However, the determinants of cataractogenesis induced by densely ionizing radiation have not been clearly elucidated. In the current study, we show that age at the time of exposure is a key determinant of cataractogenesis in rats whose eyes have been exposed to 2 Gy of (56)Fe ions. The rate of progression of cataractogenesis was significantly greater in the irradiated eyes of 1-year-old rats compared to young (56-day-old) rats. Furthermore, older ovariectomized rats that received exogenous estrogen treatment (17-β-estradiol) commencing 1 week prior to irradiation and continuing throughout the period of observation of up to approximately 600 days after irradiation showed an increased incidence of cataracts and faster progression of opacification compared to intact rats with endogenous estrogen or ovariectomized rats. The same potentiating effect (higher incidence, reduced latent period) was observed for irradiated eyes of young rats. Modulation of estrogen status in the 1-year-old animals (e.g., removal of estrogen by ovariectomy or continuous exposure to estrogen) did not increase the latent period or reduce the incidence to that of intact 56-day-old rats. Since the rapid onset and progression of cataracts in 1-year-old compared to 56-day-old rats was independent of estrogen status, we conclude that estrogen cannot account for the age-dependent differences in cataractogenesis induced by high-LET radiation. PMID:21175345

  11. Radiation resistence of microorganisms from radiation sterilization processing environments

    NASA Astrophysics Data System (ADS)

    Sabovljev, Svetlana A.; Žunić, Zora S.

    The radiation resistance of microorganisms was examined on the samples of dust collected from the radiation sterilization processing environments including assembly, storage, and sterilization plant areas. The isolation of radiation resistant strains was performed by irradiation with screening doses ranging from 10 to 35 kGy and test pieces containing 10 6 to 10 8 CFU in dried serum-broth, representing 100 to 5000 colonies of primary cultures of microorganisms from 7 different sites. In an examination of 16900 colonies of aerobic microorganisms from 3 hygienically controlled production sites and 4 uncontrolled ones, 30 strains of bacteria were isolated. Of those 15 were classified as genus Bacillus, 9 as Micrococcus and 6 as Sarcina. All of the 15 strains of Gram positive sporeforming aerobic rods exhibited an exponential decrease in the surviving fraction as a function of dose, indicating that the inactivation of spores of aerobic rods is a consequence of a single energy deposition into the target. All strains were found to be moderately resistant to radiation with D-6 values (dose required to reduce survival to 6 log cycles) between 18 and 26 kGy. All of the isolated Gram positive cocci showed inactivation curves having a shoulder, indicating that different processes are involved in the inactivation of these cells, e.g. accumulation of sublethal lesions, or final repair capacity of potential lethal lesions. Moderate radiation resistance was observed in 13 strains with D-6 values between 16 to 30 kGy. Two slow-growing, red pigmented strains tentatively classified as genus Micrococcus isolated from uncontrolled sites (human dwellings) were exceptionally resistant with D-6 more than 45 kGy. For hygienically controlled sites, Gram positive spereforming rods composed two thirds of the resistant microflora, while Gram positive cocci comprised one third. For hygienically uncontrolled sites this ratio was reversed. An assumption is made that one isolated strain has grown

  12. Effect of ionizing radiation on the transcription levels of cell stress marker genes in the Pacific oyster Crassostrea gigas.

    PubMed

    Farcy, Emilie; Voiseux, Claire; Robbes, Ismaël; Lebel, Jean-Marc; Fievet, Bruno

    2011-07-01

    In the North-Cotentin (Normandy, France), the marine environment is chronically exposed to liquid releases from the La Hague nuclear fuel recycling plant (Areva NC), resulting in a small increase in radioactivity compared to natural background. The transcriptional expression levels of stress genes were investigated in oysters exposed to ionizing radiation. Adult oysters were kept for 6 weeks in (60)Co-labeled seawater (400 Bq liter(-1)), resulting in a total dose of 6.2 mGy. Transcriptional expression of target genes was monitored by reverse-transcription quantitative polymerase chain reaction. Nine genes were selected for their sensitivity to ionizing radiation based on the literature and available DNA sequences. They included genes encoding chaperone proteins and genes involved in oxidative stress regulation, cell detoxification and cell cycle regulation. Of the nine genes of interest, metallothionein (MT) and multi-drug resistance (MDR) displayed significant overexpression in response to chronic exposure to an internal low dose. For comparison, oysters were acutely exposed to an external high dose for 100 min, resulting in 20 Gy, and the same target gene expression analysis was carried out. As in the case of chronic exposure to the low dose, MT and MDR displayed significant increases. The results suggest that the transcriptional expression levels of cell stress genes may be used as a biosensor of exposure of oysters to ionizing radiation, with a particular focus on the MT and MDR genes. However, the upregulation of these potential players in the cellular response to radiation-induced stress was not correlated with mortality or apparent morbidity. The possible role of these stress genes in the resistance of oysters to ionizing radiation is discussed. PMID:21574864

  13. Mars Surface Ionizing Radiation Environment: Need for Validation

    NASA Astrophysics Data System (ADS)

    Wilson, J. W.; Kim, M. Y.; Clowdsley, M. S.; Heinbockel, J. H.; Tripathi, R. K.; Singleterry, R. C.; Shinn, J. L.; Suggs, R.

    1999-01-01

    Protection against the hazards from exposure to ionizing radiation remains an unresolved issue in the Human Exploration and Development of Space (HEDS) enterprise [1]. The major uncertainty is the lack of data on biological response to galactic cosmic ray (GCR) exposures but even a full understanding of the physical interaction of GCR with shielding and body tissues is not yet available and has a potentially large impact on mission costs. "The general opinion is that the initial flights should be short-stay missions performed as fast as possible (so-called 'Sprint' missions) to minimize crew exposure to the zero-g and space radiation environment, to ease requirements on system reliability, and to enhance the probability of mission success." The short-stay missions tend to have long transit times and may not be the best option due to the relatively long exposure to zero-g and ionizing radiation. On the other hand the short-transit missions tend to have long stays on the surface requiring an adequate knowledge of the surface radiation environment to estimate risks and to design shield configurations. Our knowledge of the surface environment is theoretically based and suffers from an incomplete understanding of the physical interactions of GCR with the Martian atmosphere, Martian surface, and intervening shield materials. An important component of Mars surface robotic exploration is the opportunity to test our understanding of the Mars surface environment. The Mars surface environment is generated by the interaction of Galactic Cosmic Rays (GCR) and Solar Particle Events (SPEs) with the Mars atmosphere and Mars surface materials. In these interactions, multiple charged ions are reduced in size and secondary particles are generated, including neutrons. Upon impact with the Martian surface, the character of the interactions changes as a result of the differing nuclear constituents of the surface materials. Among the surface environment are many neutrons diffusing from

  14. Influence of Ionizing Radiation on Two Generations of Cochlear Implants

    PubMed Central

    Guevara, Nicolas; Gérard, Anaïs; Dupré, Jeanne; Goursonnet, Delphine; Hoen, Michel; Gnansia, Dan; Angellier, Gaëlle; Thariat, Juliette

    2015-01-01

    The purpose of the present study was to test the behavior of two different generations of cochlear implant systems subjected to a clinical radiotherapy scheme and to determine the maximal acceptable cumulative radiation levels at which the devices show out-of-specification behaviors. Using stereotactic irradiation (Cyberknife, 6 MV photon beam), three Digisonic SP and three Neuro devices were submitted to 5 Gy doses that cumulated to 60 Gy (12 sessions) and 80 Gy (16 sessions), respectively. A follow-up series of irradiation was then applied, in which Digisonic SP devices received two additional fractions of 50 Gy each, cumulating to 160 Gy, and Neuro devices three additional fractions of 20, 40, and 150 Gy, cumulating to 290 Gy. Output current values were monitored during the treatment. At clinical doses, with 60 or 80 Gy cumulative radiation exposure, no single measurement showed more than 10% divergence from the reference measure. The cochlear implants tested in this study showed high resistance to clinically relevant cumulative radiation doses and showed no out-of-bounds behavior up to cumulative doses of 140 or 160 Gy. These observations suggest that cochlear implant users can undergo radiotherapy up to cumulative doses well above those currently used in clinical situations without risk of failure. PMID:26491679

  15. Influence of Ionizing Radiation on Two Generations of Cochlear Implants.

    PubMed

    Guevara, Nicolas; Gérard, Anaïs; Dupré, Jeanne; Goursonnet, Delphine; Hoen, Michel; Gnansia, Dan; Angellier, Gaëlle; Thariat, Juliette

    2015-01-01

    The purpose of the present study was to test the behavior of two different generations of cochlear implant systems subjected to a clinical radiotherapy scheme and to determine the maximal acceptable cumulative radiation levels at which the devices show out-of-specification behaviors. Using stereotactic irradiation (Cyberknife, 6 MV photon beam), three Digisonic SP and three Neuro devices were submitted to 5 Gy doses that cumulated to 60 Gy (12 sessions) and 80 Gy (16 sessions), respectively. A follow-up series of irradiation was then applied, in which Digisonic SP devices received two additional fractions of 50 Gy each, cumulating to 160 Gy, and Neuro devices three additional fractions of 20, 40, and 150 Gy, cumulating to 290 Gy. Output current values were monitored during the treatment. At clinical doses, with 60 or 80 Gy cumulative radiation exposure, no single measurement showed more than 10% divergence from the reference measure. The cochlear implants tested in this study showed high resistance to clinically relevant cumulative radiation doses and showed no out-of-bounds behavior up to cumulative doses of 140 or 160 Gy. These observations suggest that cochlear implant users can undergo radiotherapy up to cumulative doses well above those currently used in clinical situations without risk of failure. PMID:26491679

  16. Hematopoietic Stem Cell Injury Induced by Ionizing Radiation

    PubMed Central

    Shao, Lijian; Luo, Yi

    2014-01-01

    Abstract Significance: Exposure to ionizing radiation (IR) as the result of nuclear accidents or terrorist attacks is a significant threat and a major medical concern. Hematopoietic stem cell (HSC) injury is the primary cause of death after accidental or intentional exposure to a moderate or high dose of IR. Protecting HSCs from IR should be a primary goal in the development of novel medical countermeasures against radiation. Recent Advances: Significant progress has been made in our understanding of the mechanisms by which IR causes HSC damage. The mechanisms include (i) induction of HSC apoptosis via the p53-Puma pathway; (ii) promotion of HSC differentiation via the activation of the G-CSF/Stat3/BATF-dependent differentiation checkpoint; (iii) induction of HSC senescence via the ROS-p38 pathway; and (iv) damage to the HSC niche. Critical Issues: Induction of apoptosis in HSCs and hematopoietic progenitor cells is primarily responsible for IR-induced acute bone marrow (BM) injury. Long-term BM suppression caused by IR is mainly attributable to the induction of HSC senescence. However, the promotion of HSC differentiation and damage to the HSC niche can contribute to both the acute and long-term effects of IR on the hematopoietic system. Future Directions: In this review, we have summarized a number of recent findings that provide new insights into the mechanisms whereby IR damages HSCs. These findings will provide new opportunities for developing a mechanism-based strategy to prevent and/or mitigate IR-induced BM suppression. Antioxid. Redox Signal. 20, 1447–1462. PMID:24124731

  17. Ionizing radiation induces heritable disruption of epithelial cell interactions

    NASA Technical Reports Server (NTRS)

    Park, Catherine C.; Henshall-Powell, Rhonda L.; Erickson, Anna C.; Talhouk, Rabih; Parvin, Bahram; Bissell, Mina J.; Barcellos-Hoff, Mary Helen; Chatterjee, A. (Principal Investigator)

    2003-01-01

    Ionizing radiation (IR) is a known human breast carcinogen. Although the mutagenic capacity of IR is widely acknowledged as the basis for its action as a carcinogen, we and others have shown that IR can also induce growth factors and extracellular matrix remodeling. As a consequence, we have proposed that an additional factor contributing to IR carcinogenesis is the potential disruption of critical constraints that are imposed by normal cell interactions. To test this hypothesis, we asked whether IR affected the ability of nonmalignant human mammary epithelial cells (HMEC) to undergo tissue-specific morphogenesis in culture by using confocal microscopy and imaging bioinformatics. We found that irradiated single HMEC gave rise to colonies exhibiting decreased localization of E-cadherin, beta-catenin, and connexin-43, proteins necessary for the establishment of polarity and communication. Severely compromised acinar organization was manifested by the majority of irradiated HMEC progeny as quantified by image analysis. Disrupted cell-cell communication, aberrant cell-extracellular matrix interactions, and loss of tissue-specific architecture observed in the daughters of irradiated HMEC are characteristic of neoplastic progression. These data point to a heritable, nonmutational mechanism whereby IR compromises cell polarity and multicellular organization.

  18. Nitrate deposition following an astrophysical ionizing radiation event

    NASA Astrophysics Data System (ADS)

    Neuenswander, Ben; Melott, Adrian

    2015-06-01

    It is known that a gamma ray burst (GRB) originating near the Earth could be devastating to life. The mechanism of ozone depletion and subsequent increased UVB exposure is the primary risk, but models also show increased nitrification culminating in nitric acid rainout. These effects are also expected after nearby supernovae and extreme solar proton events. In this work we considered specifically whether the increased nitric acid rainout from such events is a threat to modern terrestrial ecosystems. We also considered its potential benefit to early terrestrial Paleozoic ecosystems. We used established critical loads for nitrogen deposition in ecoregions of Europe and the US and compared them with previously predicted values of nitric acid rainout from a typical GRB within our galaxy. The predicted rainout was found to be too low to harm modern ecosystems, however, it is large compared with probable nitrate flux onto land prior to the invasion of plants. We suggest that this flux may have contributed nutrients to this invasion if, as hypothesized, the end-Ordovician extinction event were initiated by a GRB or other ionizing radiation event.

  19. Studying Simple Molecular Ionization using Radiation Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Proctor, Christopher; Lemmer, Kristina; Western Michigan University Aerospace LaboratoryPlasma Experiments Team

    2015-11-01

    This study focuses on radiation emission from the formation of simple molecular plasma using a DC glow discharge. The purpose is to measure the emission from argon and molecular nitrogen gas as a function of time with an optical emission spectroscopy system operating in kinetic mode as the gases go from their neutral state to ionized state. The end goal of the research is to develop a diagnostic tool that will be used to study the formation of plasma discharges from complex molecules. The kinetic mode of the CCD camera allows for fast data acquisition so that the species present and their relative concentrations as a function of time can be measured as the plasma is forming. The primary difficulty in the development of this diagnostic tool is designing a device and data analysis technique to allow for kinetic mode operation of the CCD camera. Experimental devices have been designed and built to enable the CCD to operate in kinetic mode, including a fiber optic adapter, camera mount, and twin razor blade system. The twin blades allow for the reduction of exposed pixels on the CCD camera and thereby allow the camera to store data on rows of pixels, rather than imaging the entire camera, allowing for faster data transfer. PhD in Aerospace Engineering.

  20. Ionizing radiation induces heritable disruption of epithelial cell interactions

    PubMed Central

    Park, Catherine C.; Henshall-Powell, Rhonda L.; Erickson, Anna C.; Talhouk, Rabih; Parvin, Bahram; Bissell, Mina J.; Barcellos-Hoff, Mary Helen

    2003-01-01

    Ionizing radiation (IR) is a known human breast carcinogen. Although the mutagenic capacity of IR is widely acknowledged as the basis for its action as a carcinogen, we and others have shown that IR can also induce growth factors and extracellular matrix remodeling. As a consequence, we have proposed that an additional factor contributing to IR carcinogenesis is the potential disruption of critical constraints that are imposed by normal cell interactions. To test this hypothesis, we asked whether IR affected the ability of nonmalignant human mammary epithelial cells (HMEC) to undergo tissue-specific morphogenesis in culture by using confocal microscopy and imaging bioinformatics. We found that irradiated single HMEC gave rise to colonies exhibiting decreased localization of E-cadherin, β-catenin, and connexin-43, proteins necessary for the establishment of polarity and communication. Severely compromised acinar organization was manifested by the majority of irradiated HMEC progeny as quantified by image analysis. Disrupted cell–cell communication, aberrant cell–extracellular matrix interactions, and loss of tissue-specific architecture observed in the daughters of irradiated HMEC are characteristic of neoplastic progression. These data point to a heritable, nonmutational mechanism whereby IR compromises cell polarity and multicellular organization. PMID:12960393

  1. The risk linked to ionizing radiation: an alternative epidemiologic approach.

    PubMed Central

    de Brouwer, C; Lagasse, R

    2001-01-01

    Radioprotection norms have been based on risk models that have evolved over time. These models show relationships between exposure and observed effects. There is a high level of uncertainty regarding lower doses. Recommendations have been based on the conservative hypothesis of a linear relationship without threshold value. This relationship is still debated, and the diverse observations do not allow any definitive conclusion. Available data are contradictory, and various interpretations can be made. Here we review an alternative approach for defining causation and reconciling apparently contradictory conclusions. This alternative epidemiologic approach is based on causal groups: Each component of a causal group is necessary but not sufficient for causality. Many groups may be involved in causality. Thus, ionizing radiation may be a component of one or several causal groups. This formalization reconciles heterogeneous observations but implies searching for the interactions between components, mostly between critical components of a causal profile, and, for instance, the reasons why specific human groups would not show any effect despite exposure, when an effect would be expected. PMID:11673115

  2. Modeling Natural Space Ionizing Radiation Effects on External Materials

    NASA Technical Reports Server (NTRS)

    Alstatt, Richard L.; Edwards, David L.; Parker, Nelson C. (Technical Monitor)

    2000-01-01

    Predicting the effective life of materials for space applications has become increasingly critical with the drive to reduce mission cost. Programs have considered many solutions to reduce launch costs including novel, low mass materials and thin thermal blankets to reduce spacecraft mass. Determining the long-term survivability of these materials before launch is critical for mission success. This presentation will describe an analysis performed on the outer layer of the passive thermal control blanket of the Hubble Space Telescope. This layer had degraded for unknown reasons during the mission, however ionizing radiation (IR) induced embrittlement was suspected. A methodology was developed which allowed direct comparison between the energy deposition of the natural environment and that of the laboratory generated environment. Commercial codes were used to predict the natural space IR environment model energy deposition in the material from both natural and laboratory IR sources, and design the most efficient test. Results were optimized for total and local energy deposition with an iterative spreadsheet. This method has been used successfully for several laboratory tests at the Marshall Space Flight Center. The study showed that the natural space IR environment, by itself, did not cause the premature degradation observed in the thermal blanket.

  3. Detecting excess ionizing radiation by electromagnetic breakdown of air

    SciTech Connect

    Granatstein, Victor L.; Nusinovich, Gregory S.

    2010-09-15

    A scheme is proposed for detecting a concealed source of ionizing radiation by observing the occurrence of breakdown in atmospheric air by an electromagnetic wave whose electric field surpasses the breakdown field in a limited volume. The volume is chosen to be smaller than the reciprocal of the naturally occurring concentration of free electrons. The pulse duration of the electromagnetic wave must exceed the avalanche breakdown time (10-200 ns) and could profitably be as long as the statistical lag time in ambient air (typically, microseconds). Candidate pulsed electromagnetic sources over a wavelength range, 3 mm>{lambda}>10.6 {mu}m, are evaluated. Suitable candidate sources are found to be a 670 GHz gyrotron oscillator with 200 kW, 10 {mu}s output pulses and a Transversely Excited Atmospheric-Pressure (TEA) CO{sub 2} laser with 30 MW, 100 ns output pulses. A system based on 670 GHz gyrotron would have superior sensitivity. A system based on the TEA CO{sub 2} laser could have a longer range >100 m.

  4. Coupling the emission of ionizing radiation and Lyman alpha

    NASA Astrophysics Data System (ADS)

    Hayes, Matthew

    2013-10-01

    The class of objects that reionized intergalactic hydrogen remains an observational and theoretical problem that is in contention for being the most prominent puzzle piece in contemporary astrophysics. The current consensus - determined almost entirely by ruling out bright active galaxies - is that the process was possibly begun and almost certainly finished by faint, lower-mass galaxies forming their early generations of stars. Recent observations of z 3 galaxies may even have identified the analog populations.However understanding how the emitted ionizing power of galaxies is causally related to their {robustly determined} physical properties is not a study that can be performed at high-z: neither the spatial information nor the standard multi-wavelength diagnostics are available. Moreover, on a case-by-case basis, the intervening IGM absorption is impossible to determine. These considerations have spawned a number of detailed studies with UV space telescopes, the synthesis of which however is that a characteristic population of Lyman continuum {LyC} emitting objects has not yet been identified. We show in this proposal that we have identified a characteristic trait in galaxy spectra that is highly indicative of LyC emission, by combining {a} high-z phenomenological studies, {b} new high-resolution UV spectra of local galaxies, and {c} sophisticated models of radiation transport. Believing that we have determined the signature, we propose to test the new hypothesis with deep spectroscopic observations with HST/COS under the Cycle 21 UV initiative.

  5. Radioprotective Potential of Plants and Herbs against the Effects of Ionizing Radiation

    PubMed Central

    C. Jagetia, Ganesh

    2007-01-01

    Ionizing radiations produce deleterious effects in the living organisms and the rapid technological advancement has increased human exposure to ionizing radiations enormously. There is a need to protect humans against such effects of ionizing radiation. Attempts to protect against the deleterious effects of ionizing radiations by pharmacological intervention were made as early as 1949 and efforts are continued to search radioprotectors, which may be of great help for human application. This review mainly dwells on the radioprotective potential of plant and herbal extracts. The results obtained from in vitro and in vivo studies indicate that several botanicals such as Gingko biloba, Centella asiatica, Hippophae rhamnoides, Ocimum sanctum, Panax ginseng, Podophyllum hexandrum, Amaranthus paniculatus, Emblica officinalis, Phyllanthus amarus, Piper longum, Tinospora cordifoila, Mentha arvensis, Mentha piperita, Syzygium cumini, Zingiber officinale, Ageratum conyzoides, Aegle marmelos and Aphanamixis polystachya protect against radiation-induced lethality, lipid peroxidation and DNA damage. The fractionation-guided evaluation may help to develop new radioprotectors of desired activities. PMID:18188408

  6. Reduction of the Background Magnetic Field Inhibits Ability of Drosophila melanogaster to Survive Ionizing Radiation

    PubMed Central

    Portelli, Lucas; Madapatha, Dinu; Martino, Carlos; Hernandez, Mark; Barnes, Frank

    2012-01-01

    The effects of exposure to an environment where the background magnetic field has been reduced were studied on wild-type Drosophila melanogaster by measuring its ability to survive a single exposure to ionizing radiation during its larval stage. The experimental design presented shows a timeframe, ionizing radiation dose and background magnetic field parameters that will cause a significant and reproducible reduction of survival on this insect model. These results suggest that background magnetic fields may play a fundamental role in the recovery or harm of a biological system that is exposed to single doses of ionizing radiation. PMID:22532126

  7. High resistivity silicon radiation detectors

    NASA Astrophysics Data System (ADS)

    Segal, Julie Diane

    This work addresses the use of silicon detectors both for charged particles in a high energy physics application, and for electromagnetic radiation, specifically x-ray and γ-ray detectors. The second generation of a PIN diode array pixel detector integrated with full twin well CMOS was developed for high energy particle physics. A new vertical high voltage diode termination structure was developed and compared to other diode termination structures through simulations. The new structure reduced the process complexity and improved the yield and robustness to mechanical damage to the backside, allowing us to build a much larger detector with denser frontside patterning, implementing a new sparse-field read-out design. Radiation measurements from this pixel detector are presented, which represent the first integrated sparse-field read-out results ever reported. A prototype 1mm thick PIN diode array x-ray detector with a depletion voltage of 800V was simulated, designed and fabricated for protein crystallography. Using 2D simulations, an optimized 5 floating ring high voltage structure was designed and implemented. Preliminary measurements indicate that the detector can be operated successfully up to 1000V. A new cylindrical drift detector was developed for x-ray absorbtion spectroscopy. To minimize the drift time, an analytic expression for drift field and 2D simulations were used to optimize the applied surface potential for a uniform drift field. Three novel integrated transistors for first stage amplification were designed and fabricated, which show promise of working with fairly straightforward optimization. A new technique for controlling dark current due to surface generation was introduced and implemented successfully. Instead of collecting the surface current at a guard anode, surface generation is suppressed by putting n+ diffusion rings between the p+ rings, dramatically reducing the depleted oxide interface area which is the site for surface generation

  8. Review of US Army ionizing-radiation dosimetry system. Final report

    SciTech Connect

    Not Available

    1986-01-01

    Army civilian and military personnel are exposed occupationally to various forms of ionizing radiation, and the U.S. Army Ionizing Radiation Dosimetry Center is responsible for monitoring these exposures. There are several accepted methods for monitoring radiation exposure, the oldest being the film badge method. A modern alternative method, which has achieved widespread acceptance, is the thermoluminescent dosimeter (TLD) badge. Inasmuch as the Radiation Dosimetry Center is in the process of converting from film badges to TLD badges for radiation monitoring, the Army requested assistance on how it might optimize the transition to this new monitoring system.

  9. Impact of bias conditions on electrical stress and ionizing radiation effects in Si-based TFETs

    NASA Astrophysics Data System (ADS)

    Ding, Lili; Gnani, Elena; Gerardin, Simone; Bagatin, Marta; Driussi, Francesco; Selmi, Luca; Royer, Cyrille Le; Paccagnella, Alessandro

    2016-01-01

    The interplay between electrical stress and ionizing radiation effects is experimentally investigated in Si-based Tunnel Field Effect Transistors (TFETs). In particular, the impact of bias conditions on the performance degradation is discussed. We found that the electrical stress effects in TFETs could not be ignored in radiation tests, since they can possibly overwhelm the radiation-induced degradation. Under this circumstance, the worst-case bias condition for studying radiation effects is not straightforward to be determined when there is an interplay between electrical stress and ionizing radiation effects.

  10. Accumulation of Mn(II) in Deinococcus radiodurans Facilitates Gamma-Radiation Resistance

    SciTech Connect

    Daly, Michael J.; Gaidamakova, E; Matrosova, V; Vasilenko, A; Zhai, M; Venkateswaran, Amudhan; Hess, M; Omelchenko, M V.; Kostandarithes, Heather M.; Makarova, S; Wackett, L. P.; Fredrickson, Jim K.; Ghosal, D

    2004-11-05

    Deinococcus radiodurans is extremely resistant to ionizing radiation. How this bacterium can grow under chronic gamma-radiation (50 Gy/hour) or recover from acute doses greater than 10 kGy is unknown. We show that D. radiodurans accumulates very high intracellular manganese and low iron levels compared to radiation sensitive bacteria, and resistance exhibits a concentration-dependent response to Mn(II). Among the most radiation-resistant bacterial groups reported, Deinococcus, Enterococcus, Lactobacillus and cyanobacteria spp. accumulate Mn(II). In contrast, Shewanella oneidensis and Pseudomonas putida have high Fe but low intracellular Mn concentrations and are very sensitive. We propose that Mn(II) accumulation facilitates recovery from radiation injury.

  11. Sustainably Sourced, Thermally Resistant, Radiation Hard Biopolymer

    NASA Technical Reports Server (NTRS)

    Pugel, Diane

    2011-01-01

    This material represents a breakthrough in the production, manufacturing, and application of thermal protection system (TPS) materials and radiation shielding, as this represents the first effort to develop a non-metallic, non-ceramic, biomaterial-based, sustainable TPS with the capability to also act as radiation shielding. Until now, the standing philosophy for radiation shielding involved carrying the shielding at liftoff or utilizing onboard water sources. This shielding material could be grown onboard and applied as needed prior to different radiation landscapes (commonly seen during missions involving gravitational assists). The material is a bioplastic material. Bioplastics are any combination of a biopolymer and a plasticizer. In this case, the biopolymer is a starch-based material and a commonly accessible plasticizer. Starch molecules are composed of two major polymers: amylase and amylopectin. The biopolymer phenolic compounds are common to the ablative thermal protection system family of materials. With similar constituents come similar chemical ablation processes, with the potential to have comparable, if not better, ablation characteristics. It can also be used as a flame-resistant barrier for commercial applications in buildings, homes, cars, and heater firewall material. The biopolymer is observed to undergo chemical transformations (oxidative and structural degradation) at radiation doses that are 1,000 times the maximum dose of an unmanned mission (10-25 Mrad), indicating that it would be a viable candidate for robust radiation shielding. As a comparison, the total integrated radiation dose for a three-year manned mission to Mars is 0.1 krad, far below the radiation limit at which starch molecules degrade. For electron radiation, the biopolymer starches show minimal deterioration when exposed to energies greater than 180 keV. This flame-resistant, thermal-insulating material is non-hazardous and may be sustainably sourced. It poses no hazardous

  12. Process for crosslinking methylene-containing aromatic polymers with ionizing radiation

    NASA Technical Reports Server (NTRS)

    Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

    1990-01-01

    A process for crosslinking aromatic polymers containing radiation-sensitive methylene groups (-CH2-) by exposing the polymers to ionizing radiation thereby causing crosslinking of the polymers through the methylene groups is described. Crosslinked polymers are resistant to most organic solvents such as acetone, alcohols, hydrocarbons, methylene, chloride, chloroform, and other halogenated hydrocarbons, to common fuels and to hydraulic fluids in contrast to readily soluble uncrosslinked polymers. In addition, the degree of crosslinking of the polymers depends upon the percentage of the connecting groups which are methylene which ranges from 5 to 50 pct and preferably from 25 to 50 pct of the connecting groups, and is also controlled by the level of irradiation which ranges from 25 to 1000 Mrads and preferably from 25 to 250 Mrads. The temperature of the reaction conditions ranges from 25 to 200 C and preferably at or slightly above the glass transition temperature of the polymer. The crosslinked polymers are generally more resistant to degradation at elevated temperatures such as greater than 150 C, have a reduced tendency to creep under load, and show no significant embrittlement of parts fabricated from the polymers.

  13. Sonic Hedgehog Signaling Protects Human Hepatocellular Carcinoma Cells Against Ionizing Radiation in an Autocrine Manner

    SciTech Connect

    Chen, Yu-Jen; Lin, Chin-Ping; Hsu, Ming-Ling; Shieh, Hui-Ru; Chao, Nicholas K.; Chao, K.S. Clifford

    2011-07-01

    Purpose: Sonic hedgehog (Shh) signaling is critical to embryogenesis and resistance to chemotherapy. We aimed to examine the role of Shh signaling in the response to radiation of human hepatocellular carcinoma (HCC) cells. Methods and Materials: Response to ionizing radiation therapy (RT) was evaluated by clonogenic assay. Quantitative RT-polymerase chain reaction for patched-1 (PTCH-1) expression was performed. Cytosolic accumulation of Shh and nuclear translocation of Gli-1 were assessed by immunofluorescence. Gli-1 knockdown was done by RNA interference (RNAi). Immunoprecipitation was performed to detect Shh ligand in conditioned medium. Immunofluorescent stain for {gamma}-H2AX was used as an index of DNA double strand breaks (DSB). Expression of proteins related to DNA damage repair was assessed by Western blotting. Results: We found that Shh ligand could protect human HCC HA22T and Sk-Hep1 cells against RT. In HA22T cells, Shh ligand activated the Shh signaling with upregulation of Shh, PTCH-1, and Gli-1 expression. The nuclear translocation of Gli-1 further supports the activation of Gli-1. The radioprotection by Shh ligand was partly blocked by Shh antibody neutralization and was abolished by Gli-1 RNAi, suggesting a critical role of Shh signaling in radiation resistance. Furthermore, we noted that soluble factors secreted into conditioned medium, either constitutively or responding to radiation, by HA22T or Sk-Hep1 cells protected subsequent culturing cells against RT. Immunoprecipitation shows the presence of Shh peptide in conditioned medium. Intriguingly, antibody neutralization of Shh ligand or knockdown of Gli-1 reversed the radioprotective effect of conditioned medium. Furthermore, Shh ligand reduced the RT-induced phosphorylation of checkpoint kinase 1 and impaired the repair of DNA DSB. Conclusions: Activation of Shh signaling protects HCC cells against ionizing radiation in an autocrine manner. Impairment of DNA damage repair might involve

  14. The measuring of the absorbed dose in human tissue that underwent irradiation with ionizing radiation

    NASA Astrophysics Data System (ADS)

    Bercea, S.; Nikolic, A.; Cenusa, C.; Celarel, A.

    2010-07-01

    Ionizing radiations are radiations of atomic origin (X) or nuclear origin (α, β, γ). They are composed of either subatomic particles (α, β) or electromagnetic waves (X, γ) which possess enough energy to remove electrons from the atoms and molecules of the medium with which particles interact. They thus generate ionizing processes. The effects that are produced by the interaction of the ionizing radiations with a particular medium (which could be human tissue) have different intensities depending on the nature of the incident radiations, on the rate in which these radiations release energy to the medium and on the total amount of energy released to the medium. For this reason, the energy released by a particular type of ionizing radiations to a particular type of medium has become of great interest both for researchers and for specialists who deal with using ionizing radiations in different fields, such as the biomedical one. The aim of the present paper is to briefly present some of the aspects connected to the way certain quantities are defined, quantities which are specific to the interaction of ionizing particles with the medium they pass through and which are also connected to the energy released in the medium. The paper also describes methods of measuring these quantities.

  15. Long-term biological effects induced by ionizing radiation--implications for dose mediated risk.

    PubMed

    Miron, S D; Astărăstoae, V

    2014-01-01

    Ionizing radiations are considered to be risk agents that are responsible for the effects on interaction with living matter. The occurring biological effects are due to various factors such as: dose, type of radiation, exposure time, type of biological tissue, health condition and the age of the person exposed. The mechanisms involved in the direct modifications of nuclear DNA and mitochondrial DNA are reviewed. Classical target theory of energy deposition in the nucleus that causes DNA damages, in particular DNA double-strand breaks and that explanation of the biological consequences of ionizing radiation exposure is a paradigm in radiobiology. Recent experimental evidences have demonstrated the existence of a molecular mechanism that explains the non-targeted effects of ionizing radiation exposure. Among these novel data, genomic instability and a variety of bystander effects are discussed here. Those bystander effects of ionizing radiation are fulfilled by cellular communication systems that give rise to non-targeted effects in the neighboring non irradiated cells. This paper provides also a commentary on the synergistic effects induced by the co-exposures to ionizing radiation and various physical agents such as electromagnetic fields and the co-exposures to ionizing radiation and chemical environmental contaminants such as metals. The biological effects of multiple stressors on genomic instability and bystander effects are also discussed. Moreover, a brief presentation of the methods used to characterize cyto- and genotoxic damages is offered. PMID:25341291

  16. Effects of ionization radiation on BICMOS components for space application

    NASA Astrophysics Data System (ADS)

    Rancoita, P. G.; Croitoru, N.; ‘Angelo, P. D.; de Marchi, M.; Favalli, A.; Seidman, A.; Colder, A.; Levalois, M.; Marie, P.; Fallica, G.; Leonardi, S.; Modica, R.

    2002-12-01

    In this paper experimental results on radiation effects on a BICMOS high-speed standard commercial technology, manufactured by ST-Microelectronics, are reported. Bipolar transistors were irradiated by neutrons, ions, or by both of them. Fast neutrons, as well as other types of particles, produce defects, mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy-interstitial pairs, the so-called Frenkel pairs. Defects introduce trapping energy states which degrade the common emitter current gain . The gain degradation has bee investigated for collector current, Ic, between 1 μA and1 mA. It was found a linear dependence of Δ(1/β) = 1/β- 1/βi(where βi and β are the gain after and before tirradiation) as a function of the concentration of Frenkel pairs. The bipolar transistors made on this technology have shown to be particularly radiation resistant. For instance, npn small area transistors have a gain variation (-i)/, lower than 10% for doses of about 0.5 MRad and collector currents of 1 μA, well suited for low power consumption space application

  17. Influence of X-ray radiation on the hot star wind ionization state and on the radiative force

    NASA Astrophysics Data System (ADS)

    Krtička, Jiří; Kubát, Jiří

    2016-09-01

    Hot stars emit large amounts of X-rays, which are assumed to originate in the supersonic stellar wind. Part of the emitted X-rays is subsequently absorbed in the wind and influences its ionization state. Because hot star winds are driven radiatively, the modified ionization equilibrium affects the radiative force. We review the recent progress in modeling the influence of X-rays on the radiative equilibrium and on the radiative force. We focus particularly on single stars with X-rays produced in wind shocks and on binaries with massive components, which belong to the most luminous objects in X-rays.

  18. Effect of VEGF receptor inhibitor PTK787/ZK222548 combined with ionizing radiation on endothelial cells and tumour growth

    PubMed Central

    Hess, C; Vuong, V; Hegyi, I; Riesterer, O; Wood, J; Fabbro, D; Glanzmann, C; Bodis, S; Pruschy, M

    2001-01-01

    The vascular endothelial growth factor (VEGF) receptor is a major target for anti-angiogenesis-based cancer treatment. Here we report the treatment effect of ionizing radiation in combination with the novel orally bioavailable VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 on endothelial cell proliferation in vitro and with tumour xenografts in vivo. Combined treatment of human umbilical vein endothelial cells with increasing doses of PTK787/ZK222584 and ionizing radiation abrogated VEGF-dependent proliferation in a dose-dependent way, but inhibition of endothelial cell proliferation was not due to apoptosis induction. In vivo, a combined treatment regimen of PTK787/ZK222584 (4 × 100 mg/kg) during 4 consecutive days in combination with ionizing radiation (4 × 3 Gy) exerted a substantial tumour growth delay for radiation-resistant p53-disfunctional tumour xenografts derived from SW480 colon adenocarcinoma cells while each treatment modality alone had only a minimal effect on tumour size and neovascularization. SW480 tumours from animals that received a combined treatment regimen, displayed not only an extended tumour growth delay but also a significant decrease in the number of microvessels in the tumour xenograft. These results support the model of a cooperative antitumoural effect of angiogenesis inhibitor and irradiation and show that the orally bioavailable VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 is suitable for combination therapy with irradiation. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11747347

  19. The Ionizing Radiation Environment on the International Space Station: Performance vs. Expectations for Avionics and Materials

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L.; Boeder, Paul A.; Pankop, Courtney; Reddell, Brandon

    2005-01-01

    The role of structural shielding mass in the design, verification, and in-flight performance of International Space Station (ISS), in both the natural and induced orbital ionizing radiation (IR) environments, is reported.

  20. Dynamic control over mega-ampere electron currents in metals using ionization-driven resistive magnetic fields.

    PubMed

    Sentoku, Y; d'Humières, E; Romagnani, L; Audebert, P; Fuchs, J

    2011-09-23

    The possibility of dynamically shaping mega-ampere electron currents generated in solids by ultraintense laser pulses in various conductor materials has been investigated. By tuning the target ionization dynamics, which depends both on the target material properties and on the input electron beam characteristics, we can control the growth of resistive magnetic fields that feedback on the current transport. As a result, collimation, hollowing, or filamentation of the electron beam can all be obtained. These results are beneficial for applications such as the production of secondary particles and radiation sources and fast ignition of inertial confinement fusion. PMID:22026865

  1. Ionizing radiation post-curing of objects produced by stereolithography and other methods

    DOEpatents

    Howell, David H.; Eberle, Claude C.; Janke, Christopher J.

    2000-01-01

    An object comprised of a curable material and formed by stereolithography or another three-dimensional prototyping method, in which the object has undergone initial curing, is subjected to post-curing by ionizing radiation, such as an electron beam having a predetermined beam output energy, which is applied in a predetermined dosage and at a predetermined dose rate. The post-cured object exhibits a property profile which is superior to that which existed prior to the ionizing radiation post-curing.

  2. Effect of a finite ionization rate on the radiative heating of outer planet atmospheric entry probes

    NASA Technical Reports Server (NTRS)

    Nelson, H. F.

    1982-01-01

    The influence of finite rate ionization in the inviscid gas just behind the stagnation shock wave on the radiative heating of probes entering the hydrogen-helium atmosphere of the major plants was investigated. Two opposing conclusions were reached as to how the ionization rate assumption affects the radiative transfer. Hydrogen-helium shock waves with a cold nonblowing wall boundary condition at the probe heat shield are emphasized. The study is limited to the stagnation shock layer.

  3. Frequency upconversion of electromagnetic radiation upon transmission into an ionization front

    SciTech Connect

    Savage, R.L. Jr.; Joshi, C.; Mori, W.B. )

    1992-02-17

    We have demonstrated that an underdense ionization front can significantly upshift the frequency of an impinging electromagnetic wave. Source radiation at 35 GHz was shifted to more than 116 GHz when a relativistically propagating, laser-produced ionization front interacted with microwave radiation that was confined in a resonant cavity. The amount of upshift was proportional to the plasma density in the front, in agreement with theoretical predictions.

  4. Mars Radiation Risk Assessment and Shielding Design for Long-term Exposure to Ionizing Space Radiation

    NASA Technical Reports Server (NTRS)

    Tripathi, Ram K.; Nealy, John E.

    2007-01-01

    NASA is now focused on the agency's vision for space exploration encompassing a broad range of human and robotic missions including missions to Moon, Mars and beyond. As a result, there is a focus on long duration space missions. NASA is committed to the safety of the missions and the crew, and there is an overwhelming emphasis on the reliability issues for space missions and the habitat. The cost-effective design of the spacecraft demands a very stringent requirement on the optimization process. Exposure from the hazards of severe space radiation in deep space and/or long duration missions is a critical design constraint and a potential 'show stopper'. Thus, protection from the hazards of severe space radiation is of paramount importance to the agency's vision. It is envisioned to have long duration human presence on the Moon for deep space exploration. The exposures from ionizing radiation - galactic cosmic radiation and solar particle events - and optimized shield design for a swing-by and a long duration Mars mission have been investigated. It is found that the technology of today is inadequate for safe human missions to Mars, and revolutionary technologies need to be developed for long duration and/or deep space missions. The study will provide a guideline for radiation exposure and protection for long duration missions and career astronauts and their safety.

  5. The Effects of Ionizing Radiation on Mammalian Cells.

    ERIC Educational Resources Information Center

    Biaglow, John E.

    1981-01-01

    Discusses the effects of radiation on dividing cells and factors influencing these effects; also briefly reviews the radical mechanism for radiation damage. Emphasizes the importance of oxygen in radiation effects. (CS)

  6. Ionizing Radiation: how fungi cope, adapt, and exploit with the help of melanin

    PubMed Central

    Dadachova, Ekaterina; Casadevall, Arturo

    2008-01-01

    SUMMARY OF RECENT ADVANCES Life on Earth has always existed in the flux of ionizing radiation. However, fungi seem to interact with the ionizing radiation differently from other Earth’s inhabitants. Recent data show that melanized fungal species like those from Chernobyl’s reactor respond to ionizing radiation with enhanced growth. Fungi colonize space stations and adapt morphologically to extreme conditions. Radiation exposure causes upregulation of many key genes, and an inducible microhomology-mediated recombination pathway could be a potential mechanism of adaptive evolution in eukaryotes. The discovery of melanized organisms in high radiation environments, the space stations, Antarctic mountains, and in the reactor cooling water combined with phenomenon of ‘radiotropism’ raises the tantalizing possibility that melanins have functions analogous to other energy harvesting pigments such as chlorophylls. PMID:18848901

  7. Clustered DNA damages induced in human hematopoietic cells by low doses of ionizing radiation

    NASA Technical Reports Server (NTRS)

    Sutherland, Betsy M.; Bennett, Paula V.; Cintron-Torres, Nela; Hada, Megumi; Trunk, John; Monteleone, Denise; Sutherland, John C.; Laval, Jacques; Stanislaus, Marisha; Gewirtz, Alan

    2002-01-01

    Ionizing radiation induces clusters of DNA damages--oxidized bases, abasic sites and strand breaks--on opposing strands within a few helical turns. Such damages have been postulated to be difficult to repair, as are double strand breaks (one type of cluster). We have shown that low doses of low and high linear energy transfer (LET) radiation induce such damage clusters in human cells. In human cells, DSB are about 30% of the total of complex damages, and the levels of DSBs and oxidized pyrimidine clusters are similar. The dose responses for cluster induction in cells can be described by a linear relationship, implying that even low doses of ionizing radiation can produce clustered damages. Studies are in progress to determine whether clusters can be produced by mechanisms other than ionizing radiation, as well as the levels of various cluster types formed by low and high LET radiation.

  8. High Radiation Resistance IMM Solar Cell

    NASA Technical Reports Server (NTRS)

    Pan, Noren

    2015-01-01

    Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

  9. Fervent: chemistry-coupled, ionizing and non-ionizing radiative feedback in hydrodynamical simulations

    NASA Astrophysics Data System (ADS)

    Baczynski, C.; Glover, S. C. O.; Klessen, R. S.

    2015-11-01

    We introduce a radiative transfer code module for the magnetohydrodynamical adaptive mesh refinement code FLASH 4. It is coupled to an efficient chemical network which explicitly tracks the three hydrogen species H, H2, H+ as well as C+ and CO. The module is geared towards modelling all relevant thermal feedback processes of massive stars, and is able to follow the non-equilibrium time-dependent thermal and chemical state of the present-day interstellar medium as well as that of dense molecular clouds. We describe in detail the implementation of all relevant thermal stellar feedback mechanisms, i.e. photoelectric, photoionization and H2 dissociation heating as well as pumping of molecular hydrogen by UV photons. All included radiative feedback processes are extensively tested. We also compare our module to dedicated photodissociation region (PDR) codes and find good agreement in our modelled hydrogen species once our radiative transfer solution reaches equilibrium. In addition, we show that the implemented radiative feedback physics is insensitive to the spatial resolution of the code and show under which conditions it is possible to obtain well-converged evolution in time. Finally, we briefly explore the robustness of our scheme for treating combined ionizing and non-ionizing radiation.

  10. Examination system utilizing ionizing radiation and a flexible, miniature radiation detector probe

    DOEpatents

    Majewski, Stanislaw; Kross, Brian J.; Zorn, Carl J.; Majewski, Lukasz A.

    1996-01-01

    An optimized examination system and method based on the Reverse Geometry X-Ray.RTM. (RGX.RTM.) radiography technique are presented. The examination system comprises a radiation source, at least one flexible, miniature radiation detector probe positioned in appropriate proximity to the object to be examined and to the radiation source with the object located between the source and the probe, a photodetector device attachable to an end of the miniature radiation probe, and a control unit integrated with a display device connected to the photodetector device. The miniature radiation detector probe comprises a scintillation element, a flexible light guide having a first end optically coupled to the scintillation element and having a second end attachable to the photodetector device, and an opaque, environmentally-resistant sheath surrounding the flexible light guide. The probe may be portable and insertable, or may be fixed in place within the object to be examined. An enclosed, flexible, liquid light guide is also presented, which comprises a thin-walled flexible tube, a liquid, preferably mineral oil, contained within the tube, a scintillation element located at a first end of the tube, closures located at both ends of the tube, and an opaque, environmentally-resistant sheath surrounding the flexible tube. The examination system and method have applications in non-destructive material testing for voids, cracks, and corrosion, and may be used in areas containing hazardous materials. In addition, the system and method have applications for medical and dental imaging.

  11. Examination system utilizing ionizing radiation and a flexible, miniature radiation detector probe

    DOEpatents

    Majewski, S.; Kross, B.J.; Zorn, C.J.; Majewski, L.A.

    1996-10-22

    An optimized examination system and method based on the Reverse Geometry X-Ray{trademark} (RGX{trademark}) radiography technique are presented. The examination system comprises a radiation source, at least one flexible, miniature radiation detector probe positioned in appropriate proximity to the object to be examined and to the radiation source with the object located between the source and the probe, a photodetector device attachable to an end of the miniature radiation probe, and a control unit integrated with a display device connected to the photodetector device. The miniature radiation detector probe comprises a scintillation element, a flexible light guide having a first end optically coupled to the scintillation element and having a second end attachable to the photodetector device, and an opaque, environmentally-resistant sheath surrounding the flexible light guide. The probe may be portable and insertable, or may be fixed in place within the object to be examined. An enclosed, flexible, liquid light guide is also presented, which comprises a thin-walled flexible tube, a liquid, preferably mineral oil, contained within the tube, a scintillation element located at a first end of the tube, closures located at both ends of the tube, and an opaque, environmentally-resistant sheath surrounding the flexible tube. The examination system and method have applications in non-destructive material testing for voids, cracks, and corrosion, and may be used in areas containing hazardous materials. In addition, the system and method have applications for medical and dental imaging. 5 figs.

  12. Analytical procedures to identify foods that have been treated with ionizing radiation

    SciTech Connect

    Morehouse, K.M.

    1994-12-31

    Foods can be treated with ionizing radiation to reduce microbial infection and insect infestations, inhibit sprouting, and delay maturation, thereby extending the shelf life of foods. The treatment of different types of foods with ionizing radiation for specific purposes is accepted in several countries, although it is prohibited in others. The U.S. Food and Drug Administration (FDA) has established regulations to allow the treatment of several different foods with ionizing radiation and has received petitions for the approval of radiation treatment of additional foods. When carried out according to established good manufacturing practices, food irradiation yields safe, wholesome foods. Often, the irradiated product may be chemically and/or microbiologically {open_quotes}safer{close_quotes} than the nonirradiated product. An area of great interest in the last several years has been the development of analytical techniques to monitor foods that have been treated with ionizing radiation. A method for the identification of irradiated foods will help to foster compliance with labeling regulations, strengthen national and international regulations for the irradiation of specific foods, and enhance consumer confidence in the safety of food commodities that have been treated with ionizing radiation.

  13. Use of Medical Imaging Procedures With Ionizing Radiation in Children: A Population-Based Study

    PubMed Central

    Dorfman, Adam L.; Fazel, Reza; Einstein, Andrew J.; Applegate, Kimberly E.; Krumholz, Harlan M.; Wang, Yongfei; Christodoulou, Emmanuel; Chen, Jersey; Sanchez, Ramon; Nallamothu, Brahmajee K.

    2013-01-01

    Objective To determine population-based rates of use of diagnostic imaging procedures with ionizing radiation in children, stratified by age and gender. Design Retrospective cohort analysis. Setting All settings utilizing imaging procedures with ionizing radiation. Patients Individuals less than 18 years old, alive and continuously enrolled in Unitedhealthcare between January 1, 2005 and December 31, 2007 in 5 large U.S. healthcare markets. Main Outcome Measure Number and type of diagnostic imaging procedures utilizing ionizing radiation in children. Results 355,088 children were identified. A total of 436,711 imaging procedures using ionizing radiation were performed in 150,930 (42.5%) patients. The highest rates of use were in children greater than 10 years old, with frequent use in infants under 2 years old as well. Plain radiography accounted for nearly 85% of imaging procedures performed. Computed tomography (CT) scans – associated with substantially higher doses of radiation – were commonly used, accounting for 12% of all procedures during the study period. Overall, 7.9% of children received at least one CT and 3.5% received 2 or more, with CT of the head most frequent. Conclusions Exposure to ionizing radiation from medical diagnostic imaging procedures may occur frequently among children. Efforts to optimize and ensure appropriate use of these procedures in the pediatric population should be encouraged. PMID:21199972

  14. Ribosome Synthesis and MAPK Activity Modulate Ionizing Radiation-Induced Germ Cell Apoptosis in Caenorhabditis elegans

    PubMed Central

    Eberhard, Ralf; Stergiou, Lilli; Hofmann, E. Randal; Hofmann, Jen; Haenni, Simon; Teo, Youjin; Furger, André; Hengartner, Michael O.

    2013-01-01

    Synthesis of ribosomal RNA by RNA polymerase I (RNA pol I) is an elemental biological process and is key for cellular homeostasis. In a forward genetic screen in C. elegans designed to identify DNA damage-response factors, we isolated a point mutation of RNA pol I, rpoa-2(op259), that leads to altered rRNA synthesis and a concomitant resistance to ionizing radiation (IR)-induced germ cell apoptosis. This weak apoptotic IR response could be phenocopied when interfering with other factors of ribosome synthesis. Surprisingly, despite their resistance to DNA damage, rpoa-2(op259) mutants present a normal CEP-1/p53 response to IR and increased basal CEP-1 activity under normal growth conditions. In parallel, rpoa-2(op259) leads to reduced Ras/MAPK pathway activity, which is required for germ cell progression and physiological germ cell death. Ras/MAPK gain-of-function conditions could rescue the IR response defect in rpoa-2(op259), pointing to a function for Ras/MAPK in modulating DNA damage-induced apoptosis downstream of CEP-1. Our data demonstrate that a single point mutation in an RNA pol I subunit can interfere with multiple key signalling pathways. Ribosome synthesis and growth-factor signalling are perturbed in many cancer cells; such an interplay between basic cellular processes and signalling might be critical for how tumours evolve or respond to treatment. PMID:24278030

  15. (Development of recommendations in the area of ionizing and nonionizing radiations)

    SciTech Connect

    Not Available

    1990-01-01

    This document discusses progress made from March 1, 1990 to October 30, 1990 in terms of publication of reports. This subjects discussed are related to the fields of radiation protection and ionizing and nonionizing radiations. Topics discussed published works, reports in press, printer's manuscript preparation, and scientific committee activities. (KJD)

  16. Effects of Ionizing Radiation on Cellular Structures, Induced Instability, and Carcinogenesis

    SciTech Connect

    Resat, Marianne S.; Arthurs, Benjamin J.; Estes, Brian J.; Morgan, William F.

    2006-03-01

    According to the American Cancer Society, the United States can expect 1,368,030 new cases of cancer in 2004 [1]. Among the many carcinogens Americans are exposed to, ionizing radiation will contribute to this statistic. Humans live in a radiation environment. Ionizing radiation is in the air we breathe, the earth we live on, and the food we eat. Man-made radiation adds to this naturally occurring radiation level thereby increasing the chance for human exposure. For many decades the scientific community, governmental regulatory bodies, and concerned citizens have struggled to estimate health risks associated with radiation exposures, particularly at low doses. While cancer induction is the primary concern and the most important somatic effect of exposure to ionizing radiation, potential health risks do not involve neoplastic diseases exclusively but also include somatic mutations that might contribute to birth defects and ocular maladies, and heritable mutations that might impact on disease risks in future generations. Consequently it is important we understand the effect of ionizingradiation on cellular structures and the subsequent long-term health risks associated with exposure to ionizing radiation.

  17. Review of the Use of Ionizing Radiation in Endovascular Aneurysm Repair.

    PubMed

    Dindyal, S; Rahman, S; Kyriakides, C

    2015-08-01

    Endovascular repair for aortic aneurysm (EVAR) is rapidly increasing in popularity. The nature of this intervention requires significant exposure to ionizing radiation both during the procedure and for postoperative surveillance, generally in the form of computed tomography. Here the authors review the literature for radiation exposure during EVAR, both for the patient and the physician. PMID:25225195

  18. Is Ionizing Radiation Harmful at any Exposure? An Echo That Continues to Vibrate.

    PubMed

    Azzam, Edouard I; Colangelo, Nicholas W; Domogauer, Jason D; Sharma, Neha; de Toledo, Sonia M

    2016-03-01

    The health risks to humans and non-human biota exposed to low dose ionizing radiation remain ambiguous and are the subject of intense debate. The need to establish risk assessment standards based on the mechanisms underlying low-level radiation exposure has been recognized by regulatory agencies as critical to adequately protect people and to make the most effective use of national resources. Here, the authors briefly review evidence showing that the molecular and biochemical changes induced by low doses of radiation differ from those induced by high doses. In particular, an array of redundant and inter-related mechanisms act in both prokaryotes and eukaryotes to restore DNA integrity following exposures to relatively low doses of sparsely ionizing radiation. Furthermore, the radiation-induced protective mechanisms often overcompensate and minimize the mutagenic potential of the byproducts of normal oxidative metabolism. In contrast to adaptive protection observed at low doses of sparsely ionizing radiation, there is evidence that even a single nuclear traversal by a densely ionizing particle track can trigger harmful effects that spread beyond the traversed cell and induce damaging effects in the nearby bystander cells. In vivo studies examining whether exposure to low dose radiation at younger age modulates the latency of expression of age-related diseases such as cancer, together with studies on the role of genetic susceptibility, will further illuminate the magnitude of risk of exposure to low dose radiation. PMID:26808874

  19. Effects of ionizing radiation on the enzyme activities and ultrastructural changes of poultry

    NASA Astrophysics Data System (ADS)

    Hwang, H.-I.; Hau, L.-B.

    1995-02-01

    Enzyme-catalyzed changes are generally recognized as one of the major reasons for fresh meat deterioration after irradiation. In this study, the effects of ionizing radiation and storage on the enzyme activities of poultry as well as the ultrastructural change of muscle were evaluated. When chicken breasts were irradiated at 4°C and -20°C, both Ca 2+-dependent protease and cathepsin D showed some degree of resistance to irradiation. The activities of those two enzymes decreased with the increase of irradiation doses. During storage, Ca 2+-dependent proteases showed a marked decrease in activity. On the other hand, the cathepsin D activity was not significantly changed at either 4°C or -20°C after 20 days. Transmission electron microscope examination showed no structural changes of the myofibrils with a radiation dose of up to 10 kGy at either 4°C or -20°C. Freezing protected the irradiated chicken breasts from autolytic enzymes damage during storage. In contrast, considerable sarcomere degradation occurred in Z-line for irradiated samples when stored at 4°C for 20 days. The action of the proteolytic enzymes may have been responsible for the sarcomere degradation in irradiated chicken breasts.

  20. Delayed activation of human microglial cells by high dose ionizing radiation.

    PubMed

    Chen, Hongxin; Chong, Zhao Zhong; De Toledo, Sonia M; Azzam, Edouard I; Elkabes, Stella; Souayah, Nizar

    2016-09-01

    Recent studies have shown that microglia affects the fate of neural stem cells in response to ionizing radiation, which suggests a role for microglia in radiation-induced degenerative outcomes. We therefore investigated the effects of γ-irradiation on cell survival, proliferation, and activation of microglia and explored associated mechanisms. Specifically, we evaluated cellular and molecular changes associated with exposure of human microglial cells (CHME5) to low and high doses of acute cesium-137 γ rays. Twenty-four hours after irradiation, cell cycle analyses revealed dose-dependent decreases in the fraction of cells in S and G2/M phase, which correlated with significant oxidative stress. By one week after irradiation, 20-30% of the cells exposed to high doses of γ rays underwent apoptosis, which correlated with significant concomitant decrease in metabolic activity as assessed by the MTT assay, and microglial activation as judged by both morphological changes and increased expression of Glut-5 and CR43. These changes were associated with increases in the mRNA levels for IL-1α, IL-10 and TNFα. Together, the results show that human CHME5 microglia are relatively resistant to low and moderate doses of γ rays, but are sensitive to acute high doses, and that CHME5 cells are a useful tool for in vitro study of human microglia. PMID:27265419

  1. An evaluation of ionizing radiation emitted by high power microwave generators

    SciTech Connect

    Lovell, C.D. ); Bolch, W.E. . Dept. of Environmental Engineering Sciences)

    1992-02-01

    Ionizing radiation emitted by electron-beam driven high power microwave (HPM) generators were measured in the near and far-field using lithium fluoride (LiF) thermoluminescent dosimeters (TLDs). Simplified photon energy spectra were determined by measuring radiation transmission, at electron beam energies of 300 to 650 keV, through various thicknesses of steel and lead attenuators. These data were used to calculate the effective energy of the x-rays produced by interactions between the electrons and the walls or other structures of the HPM generators. Operators were polled to determine locations of burn marks or other visible damage to locate potential ionizing radiation source regions. 27 refs.

  2. Thermophysics Characterization of Multiply Ionized Air Plasma Absorption of Laser Radiation

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Rhodes, Robert; Turner, Jim (Technical Monitor)

    2002-01-01

    The impact of multiple ionization of air plasma on the inverse Bremsstrahlung absorption of laser radiation is investigated for air breathing laser propulsion. Thermochemical properties of multiply ionized air plasma species are computed for temperatures up to 200,000 deg K, using hydrogenic approximation of the electronic partition function; And those for neutral air molecules are also updated for temperatures up to 50,000 deg K, using available literature data. Three formulas for absorption are calculated and a general formula is recommended for multiple ionization absorption calculation. The plasma composition required for absorption calculation is obtained by increasing the degree of ionization sequentially, up to quadruple ionization, with a series of thermal equilibrium computations. The calculated second ionization absorption coefficient agrees reasonably well with that of available data. The importance of multiple ionization modeling is demonstrated with the finding that area under the quadruple ionization curve of absorption is found to be twice that of single ionization. The effort of this work is beneficial to the computational plasma aerodynamics modeling of laser lightcraft performance.

  3. Evaluation of Awareness on Radiation Protection and Knowledge About Radiological Examinations in Healthcare Professionals Who Use Ionized Radiation at Work

    PubMed Central

    Yurt, Ayşegül; Çavuşoğlu, Berrin; Günay, Türkan

    2014-01-01

    Objective: In this study, we evaluated the knowledge and perception and mitigation of hazards involved in radiological examinations, focusing on healthcare personnel who are not in radiation-related occupations, but who use ionising radiation as a part of their work. Methods: A questionnaire was applied to physicians, nurses, technicians and other staff working in different clinics that use radiation in their work, in order to evaluate their knowledge levels about ionizing radiation and their awareness about radiation doses resulting from radiological examinations. The statistical comparisons between the groups were analyzed with the Kruskal Wallis test using the SPSS program. Results: Ninety two participants took part in the study. Their level of knowledge about ionizing radiation and doses in radiological examinations were found to be very weak. The number of correct answers of physicians, nurses, medical technicians and other personnel groups were 15.7±3.7, 13.0±4.0, 10.1±2.9 and 11.8±4.0, respectively. In the statistical comparison between the groups, the level of knowledge of physicians was found to be significantly higher than the level of the other groups (p=0.005). Conclusion: The present study demonstrated that general knowledge in relation to radiation, radiation protection, health risks and doses used for radiological applications are insufficient among health professions using with ionizing radiation in their work. PMID:24963445

  4. Ionizing Radiation Stimulates Expression of Pro-Osteoclastogenic Genes in Marrow and Skeletal Tissue

    PubMed Central

    Alwood, Joshua S.; Shahnazari, Mohammad; Chicana, Betsabel; Schreurs, A.S.; Kumar, Akhilesh; Bartolini, Alana; Shirazi-Fard, Yasaman

    2015-01-01

    Exposure to ionizing radiation can cause rapid mineral loss and increase bone-resorbing osteoclasts within metabolically active, cancellous bone tissue leading to structural deficits. To better understand mechanisms involved in rapid, radiation-induced bone loss, we determined the influence of total body irradiation on expression of select cytokines known both to stimulate osteoclastogenesis and contribute to inflammatory bone disease. Adult (16 week), male C57BL/6J mice were exposed to either 2 Gy gamma rays (137Cs, 0.8 Gy/min) or heavy ions (56Fe, 600MeV, 0.50–1.1 Gy/min); this dose corresponds to either a single fraction of radiotherapy (typical total dose is ≥10 Gy) or accumulates over long-duration interplanetary missions. Serum, marrow, and mineralized tissue were harvested 4 h—7 days later. Gamma irradiation caused a prompt (2.6-fold within 4 h) and persistent (peaking at 4.1-fold within 1 day) rise in the expression of the obligate osteoclastogenic cytokine, receptor activator of nuclear factor kappa-B ligand (Rankl), within marrow cells over controls. Similarly, Rankl expression peaked in marrow cells within 3 days of iron exposure (9.2-fold). Changes in Rankl expression induced by gamma irradiation preceded and overlapped with a rise in expression of other pro-osteoclastic cytokines in marrow (eg, monocyte chemotactic protein-1 increased by 11.9-fold, and tumor necrosis factor-alpha increased by 1.7-fold over controls). The ratio, Rankl/Opg, in marrow increased by 1.8-fold, a net pro-resorption balance. In the marrow, expression of the antioxidant transcription factor, Nfe2l2, strongly correlated with expression levels of Nfatc1, Csf1, Tnf, and Rankl. Radiation exposure increased a serum marker of bone resorption (tartrate-resistant acid phosphatase) and led to cancellous bone loss (16% decrement after 1 week). We conclude that total body irradiation (gamma or heavy-ion) caused temporal elevations in the concentrations of specific genes

  5. Ionizing Radiation Stimulates Expression of Pro-Osteoclastogenic Genes in Marrow and Skeletal Tissue

    NASA Technical Reports Server (NTRS)

    Alwood, J. S.; Shahnazari, M.; Chicana, B.; Schreurs, A. S.; Kumar, A.; Bartolini, A.; Shirazi-Fard, Y.; Globus, R. K.

    2015-01-01

    Exposure to ionizing radiation can cause rapid mineral loss and increase bone-resorbing osteoclasts within metabolically-active, cancellous-bone tissue leading to structural deficits. To better understand mechanisms involved in rapid, radiation-induced bone loss, we determined the influence of total-body irradiation on expression of select cytokines known both to stimulate osteoclastogenesis and contribute to inflammatory bone disease. Adult (16wk), male C57BL/6J mice were exposed to either 2Gy gamma rays (137Cs, 0.8Gy/min) or heavy ions (56Fe, 600MeV, 0.50-1.1Gy/min); this dose corresponds to either a single fraction of radiotherapy (typical total dose is =10Gy) or accumulates over long-duration, interplanetary missions. Serum, marrow, and mineralized tissue were harvested 4hrs-7d later. Gamma irradiation caused a prompt (2.6-fold within 4hrs) and persistent (peaking at 4.1-fold within 1d) rise in the expression of the obligate osteoclastogenic cytokine, receptor activator of nuclear factor kappaB-ligand (Rankl) within marrow cells over controls. Similarly, Rankl expression peaked in marrow cells within 3d of iron exposure (9.2-fold). Changes in Rankl expression induced by gamma irradiation preceded and overlapped with a rise in expression of other pro-osteoclastic cytokines in marrow (e.g., monocyte chemotactic protein-1 increased 11.9-fold, tumor necrosis factor-alpha increased 1.7- fold over controls). Marrow expression of the RANKL decoy receptor, osteoprotegerin (Opg), also rose after irradiation (11.3-fold). The ratio Rankl/Opg in marrow was increased 1.8-fold, a net pro-resorption balance. As expected, radiation increased a serum marker of resorption (tartrate resistant acid phosphatase) and led to cancellous bone loss (16% decrease in bone volume/total volume) through reduced trabecular struts. We conclude that total-body irradiation (gamma or heavy-ion) caused temporal, concerted regulation of gene expression within marrow and mineralized tissue for

  6. F--Ray: A new algorithm for efficient transport of ionizing radiation

    NASA Astrophysics Data System (ADS)

    Mao, Yi; Zhang, J.; Wandelt, B. D.; Shapiro, P. R.; Iliev, I. T.

    2014-04-01

    We present a new algorithm for the 3D transport of ionizing radiation, called F2-Ray (Fast Fourier Ray-tracing method). The transfer of ionizing radiation with long mean free path in diffuse intergalactic gas poses a special challenge to standard numerical methods which transport the radiation in position space. Standard methods usually trace each individual ray until it is fully absorbed by the intervening gas. If the mean free path is long, the computational cost and memory load are likely to be prohibitive. We have developed an algorithm that overcomes these limitations and is, therefore, significantly more efficient. The method calculates the transfer of radiation collectively, using the Fast Fourier Transform to convert radiation between position and Fourier spaces, so the computational cost will not increase with the number of ionizing sources. The method also automatically combines parallel rays with the same frequency at the same grid cell, thereby minimizing the memory requirement. The method is explicitly photon-conserving, i.e. the depletion of ionizing photons is guaranteed to equal the photoionizations they caused, and explicitly obeys the periodic boundary condition, i.e. the escape of ionizing photons from one side of a simulation volume is guaranteed to be compensated by emitting the same amount of photons into the volume through the opposite side. Together, these features make it possible to numerically simulate the transfer of ionizing photons more efficiently than previous methods. Since ionizing radiation such as the X-ray is responsible for heating the intergalactic gas when first stars and quasars form at high redshifts, our method can be applied to simulate thermal distribution, in addition to cosmic reionization, in three-dimensional inhomogeneous cosmological density field.

  7. Role of AKT and ERK pathways in controlling sensitivity to ionizing radiation and adaptive response induced by low-dose radiation in human immune cells.

    PubMed

    Park, Hyung Sun; You, Ga Eun; Yang, Kwang Hee; Kim, Ji Young; An, Sungkwan; Song, Jie-Young; Lee, Su-Jae; Lim, Young-Khi; Nam, Seon Young

    2015-12-01

    Despite many studies of the effect of ionizing radiation, biological mechanisms of action might differ greatly depend on dose, dose rate, and cell type. This study was performed to explore the effects of low- and high-dose radiation in human immune cell lines. We examined cell sensitivity after irradiation with 0.05, 0.1, or 2Gy in two normal cell lines and three tumor cell lines. Low-dose radiation of 0.05 and 0.1Gy had no effect on cell survival in any tested cell line, with the exception of IM-9 cells, whose viability was transiently increased. However, IM-9 and C1R-sB7 cells were very sensitive to high-dose radiation-induced cell death, whereas Jurkat and JM1 cells showed moderate sensitivity, and THP-1 cells were completely resistant. This radiosensitivity was correlated with basal AKT activation, which is induced by phosphorylation. In radiosensitive IM-9 cells, priming with chronic low-dose irradiation blocked cell death induced by high-dose radiation challenge via inhibition of caspase activation and PARP cleavage. AKT phosphorylation was not altered in IM-9 cells, but ERK phosphorylation was greatly elevated immediately after chronic low-dose irradiation. Taken together, our results suggest that the different responses of normal and tumor cells to low-dose and high-dose radiation depend on AKT activation, which is regulated by protein phosphatase 2 (PP2A). In radiosensitive normal cells lacking basal AKT activity, chronic low-dose radiation increases activation of the ERK pathway, which plays an important role in the adaptive response to radiation, providing a very important insight into understanding the effects of ionizing radiation on health. PMID:26362471

  8. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, Philip J.; Braski, David N.; Rowcliffe, Arthur F.

    1989-01-01

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01% to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties.

  9. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, P.J.; Braski, D.N.; Rowcliffe, A.F.

    1987-02-11

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01 to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties. 4 figs.

  10. TWO-DIMENSIONAL RADIATIVE MAGNETOHYDRODYNAMIC SIMULATIONS OF THE IMPORTANCE OF PARTIAL IONIZATION IN THE CHROMOSPHERE

    SciTech Connect

    Martinez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo

    2012-07-10

    The bulk of the solar chromosphere is weakly ionized and interactions between ionized particles and neutral particles likely have significant consequences for the thermodynamics of the chromospheric plasma. We investigate the importance of introducing neutral particles into the MHD equations using numerical 2.5D radiative MHD simulations obtained with the Bifrost code. The models span the solar atmosphere from the upper layers of the convection zone to the low corona, and solve the full MHD equations with non-gray and non-LTE radiative transfer, and thermal conduction along the magnetic field. The effects of partial ionization are implemented using the generalized Ohm's law, i.e., we consider the effects of the Hall term and ambipolar diffusion in the induction equation. The approximations required in going from three fluids to the generalized Ohm's law are tested in our simulations. The Ohmic diffusion, Hall term, and ambipolar diffusion show strong variations in the chromosphere. These strong variations of the various magnetic diffusivities are absent or significantly underestimated when, as has been common for these types of studies, using the semi-empirical VAL-C model as a basis for estimates. In addition, we find that differences in estimating the magnitude of ambipolar diffusion arise depending on which method is used to calculate the ion-neutral collision frequency. These differences cause uncertainties in the different magnetic diffusivity terms. In the chromosphere, we find that the ambipolar diffusion is of the same order of magnitude or even larger than the numerical diffusion used to stabilize our code. As a consequence, ambipolar diffusion produces a strong impact on the modeled atmosphere. Perhaps more importantly, it suggests that at least in the chromospheric domain, self-consistent simulations of the solar atmosphere driven by magnetoconvection can accurately describe the impact of the dominant form of resistivity, i.e., ambipolar diffusion. This

  11. Overcoming radiation resistance in inflammatory breast cancer.

    PubMed

    Woodward, Wendy A; Debeb, Bisrat G; Xu, Wei; Buchholz, Thomas A

    2010-06-01

    The clinical-pathological features of inflammatory breast cancer include enrichment of factors that have been previously associated with radioresistant disease, including negative hormone receptor status and a phenotype enriched for relatively radioresistant breast cancer stem/progenitor cells. The risks and benefits of accelerated postmastectomy radiation treatment regimens in the multimodality management of inflammatory breast cancer were reviewed at the first International Inflammatory Breast Cancer Conference at The University of Texas M. D. Anderson Cancer Center. The biological basis for radiation resistance and strategies to radiosensitize these tumors were also presented. The prevalent basal phenotype of inflammatory breast cancer makes it an ideal clinical model to examine stem cell hypotheses, which the authors believe can help guide future trials to continue making incremental progress against this aggressive disease. PMID:20503417

  12. Thermal and radiation resistance of stabilized LDPE

    NASA Astrophysics Data System (ADS)

    Zaharescu, T.; Jipa, S.; Henderson, D.; Kappel, W.; Mariş, D. A.; Mariş, M.

    2010-03-01

    The effect of capsaicin on the radiation stability of low density polyethylene was accomplished by applying the chemiluminescence procedure. The neat and modified polymer with 0.25% and 0.50% (w/w) capsaicin were exposed to γ-irradiation in air receiving 10, 20 and 30 kGy. The synergistic effect due to the presence of metallic selenium was demonstrated. The significant improvement in oxidation induction time was obtained demonstrating the efficient antioxidant activity of capsaicin in LDPE. The simultaneous protection action of metallic selenium in LDPE/capsaicin systems brought about a supplementary enhancement in the oxidation resistance of irradiated samples.

  13. Commentary: ethical issues of current health-protection policies on low-dose ionizing radiation.

    PubMed

    Socol, Yehoshua; Dobrzyński, Ludwik; Doss, Mohan; Feinendegen, Ludwig E; Janiak, Marek K; Miller, Mark L; Sanders, Charles L; Scott, Bobby R; Ulsh, Brant; Vaiserman, Alexander

    2014-05-01

    The linear no-threshold (LNT) model of ionizing-radiation-induced cancer is based on the assumption that every radiation dose increment constitutes increased cancer risk for humans. The risk is hypothesized to increase linearly as the total dose increases. While this model is the basis for radiation safety regulations, its scientific validity has been questioned and debated for many decades. The recent memorandum of the International Commission on Radiological Protection admits that the LNT-model predictions at low doses are "speculative, unproven, undetectable and 'phantom'." Moreover, numerous experimental, ecological, and epidemiological studies show that low doses of sparsely-ionizing or sparsely-ionizing plus highly-ionizing radiation may be beneficial to human health (hormesis/adaptive response). The present LNT-model-based regulations impose excessive costs on the society. For example, the median-cost medical program is 5000 times more cost-efficient in saving lives than controlling radiation emissions. There are also lives lost: e.g., following Fukushima accident, more than 1000 disaster-related yet non-radiogenic premature deaths were officially registered among the population evacuated due to radiation concerns. Additional negative impacts of LNT-model-inspired radiophobia include: refusal of some patients to undergo potentially life-saving medical imaging; discouragement of the study of low-dose radiation therapies; motivation for radiological terrorism and promotion of nuclear proliferation. PMID:24910586

  14. An ionizing radiation sensor using a pre-programmed MAHAOS device.

    PubMed

    Hsieh, Wen-Ching; Lee, Hao-Tien Daniel; Jong, Fuh-Cheng

    2014-01-01

    Metal-aluminum oxide-hafnium aluminum oxide-silicon oxide-silicon (hereafter MAHAOS) devices can be candidates for ionizing radiation sensor applications. In this work, MAHAOS devices (SONOS-like structures with high k stack gate dielectric) were studied regarding the first known characterization of the ionization radiation sensing response. The change of threshold voltage V(T) for a MAHAOS device after gamma ray exposure had a strong correlation to the total ionization dose (TID) of gamma radiation up to at least 5 Mrad TID. In this paper, the gamma radiation response performances of the pre-programmed and virgin (non-pre-programmed) MAHAOS devices are presented. The experimental data show that the change of VT for the pre-programmed MAHAOS device with gamma irradiation is very significant. The data of pre-programmed MAHAOS devices written by 5 Mrad TID of gamma radiation was also stable for a long time with data storage. The sensing of gamma radiation by pre-programmed MAHAOS devices with high k stack gate dielectric reported in this study has demonstrated their potential application for non-volatile ionizing radiation sensing technology in the future. PMID:25116901

  15. Whether ionizing radiation is a risk factor for schizophrenia spectrum disorders?

    PubMed

    Loganovsky, Konstantin N; Volovik, Sergij V; Manton, Kenneth G; Bazyka, Dimitry A; Flor-Henry, Pierre

    2005-01-01

    The neural diathesis-stressor hypothesis of schizophrenia, where neurobiological genetic predisposition to schizophrenia can be provoked by environmental stressors is considered as a model of the effects of exposure to ionizing radiation. Analysis of information from electronic databases (MEDLINE, PsycINFO, EMBASE, Current Contents, Elsevier BIOBASE) and hand-made search was carried out. There are comparable reports on increases in schizophrenia spectrum disorders following exposure to ionizing radiation as a result of atomic bombing, nuclear weapons testing, the Chernobyl accident, environmental contamination by radioactive waste, radiotherapy, and also in areas with high natural radioactive background. The results of experimental radioneurobiological studies support the hypothesis of schizophrenia as a neurodegenerative disease. Exposure to ionizing radiation causes brain damage with limbic (cortical-limbic) system dysfunction and impairment of informative processes at the molecular level that can trigger schizophrenia in predisposed individuals or cause schizophrenia-like disorders. It is supposed that ionizing radiation can be proposed as a risk factor for schizophrenia spectrum disorders. The hypothesis that ionizing radiation is a risk factor for schizophrenia spectrum disorders can be tested using data from the Chernobyl accident aftermath. Implementation of a study on schizophrenia spectrum disorders in Chernobyl accident victims is of significance for both clinical medicine and neuroscience. PMID:16272077

  16. Ionizing radiation treatment to improve postharvest life and maintain quality of fresh guava fruit

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Pal, R. K.

    2009-02-01

    We investigated the potential of ionizing radiation for improving physiological responses, quality, and storage time of fresh guava fruit. Ionizing radiation treatment suppressed the respiration and ethylene production rates and thus retarded the process of fruit ripening during storage. Irradiation treatment also retarded the physical and biochemical changes associated with ripening such as firmness, titratable acidity, soluble solids content, and vitamin C during storage, but for doses higher than 0.25 kGy the vitamin C content decreased. The positive effects of ionizing radiation treatment on delayed fruit ripening and other quality attributes diminished during 22 days of storage at 10 °C. Thus, a combination of ionizing radiation with low-temperature storage (10 °C) did not have much synergistic effect on storage life and quality of guava fruit. In conclusion, ionizing radiation treatment of guava fruit with 0.25 kGy dose increased the postharvest life by 3-4 days, maintained fruit quality, and reduced the decay incidence. The optimal dose (0.25 kGy) for postharvest life extension of guava fruit may be exploited to provide phytosanitary security against many insect pests including fruit flies.

  17. Discoloration resistant, flexible, radiation curable coating compositions

    SciTech Connect

    Cassatta, J.C.; Garrett, D.L. Jr.; Van Oene, H.

    1984-10-16

    A low dosage radiation polymerizable protective and decorative coating composition or paint, coated articles bearing such a protective coating and processess for preparing such articles. The radiation polymerizable coating composition comprises an organic resin/monomer mixture of: (A) between about 97 and about 3 weight percent alphabeta olefinically unsaturated organic resin containing between about 0.5 and about 5 vinyl unsaturation units per 1000 molecular weight of said resin, and (B) between about 3 and about 97 weight percent vinyl monomers polymerizable with said resin upon exposure to radiation, characterized in that said vinyl monomers include N-vinyl-2-pyrrolidone in an amount of from about 3 and up to about 10 weight percent based on the total weight of (A) and (B). The flexible coating exhibits excellent physical qualtities and good adhesion to a variety of substrates being particularly suitable for use on vinyl chloride fabric, wherein it is discoloration resistant after heat aging. Preferred articles bearing such a coating, which may comprise large amounts of pigment, are preferably cured by exposure to electron beam radiation.

  18. Radiation pressure confinement - III. The origin of the broad ionization distribution in AGN outflows

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Behar, Ehud; Laor, Ari; Baskin, Alexei; Holczer, Tomer

    2014-12-01

    The winds of ionized gas driven by active galactic nuclei (AGN) can be studied through absorption lines in their X-ray spectra. A recurring feature of these outflows is their broad ionization distribution, including essentially all ionization levels (e.g., Fe0+ to Fe25+). This characteristic feature can be quantified with the absorption measure distribution (AMD), defined as the distribution of column density with ionization parameter |dN/d log ξ|. Observed AMDs extend over 0.1 ≲ ξ ≲ 104 (cgs), and are remarkably similar in different objects. Power-law fits (|dN/d log ξ| ≈ N1ξa) yield N1 = 3 × 1021 cm- 2 ± 0.4 dex and a = 0-0.4. What is the source of this broad ionization distribution, and what sets the small range of observed N1 and a? A common interpretation is a multiphase outflow, with a wide range of gas densities in a uniform gas pressure medium. However, the incident radiation pressure leads to a gas pressure gradient in the photoionized gas, and therefore to a broad range of ionization states within a single slab. We show that this compression of the gas by the radiation pressure leads to an AMD with |dN/d log ξ| = 8 × 1021 ξ0.03 cm-2, remarkably similar to that observed. The calculated values of N1 and a depend weakly on the gas metallicity, the ionizing spectral slope, the distance from the nucleus, the ambient density, and the total absorber column. Thus, radiation pressure compression (RPC) of the photoionized gas provides a natural explanation for the observed AMD. RPC predicts that the gas pressure increases with decreasing ionization, which can be used to test the validity of RPC in ionized AGN outflows.

  19. 2.3.2 Biological Effects of Non-Ionizing Radiations

    NASA Astrophysics Data System (ADS)

    Bernhardt, J. H.

    This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Subsection '2.3.2 Biological Effects of Non-Ionizing Radiations' of the Section '2.3 Biological Effects' of the Chapter '2 Radiation and Biological Effects' with the contents:

  20. Adaptation of the Black Yeast Wangiella dermatitidis to Ionizing Radiation: Molecular and Cellular Mechanisms

    PubMed Central

    Robertson, Kelly L.; Mostaghim, Anahita; Cuomo, Christina A.; Soto, Carissa M.; Lebedev, Nikolai; Bailey, Robert F.; Wang, Zheng

    2012-01-01

    Observations of enhanced growth of melanized fungi under low-dose ionizing radiation in the laboratory and in the damaged Chernobyl nuclear reactor suggest they have adapted the ability to survive or even benefit from exposure to ionizing radiation. However, the cellular and molecular mechanism of fungal responses to such radiation remains poorly understood. Using the black yeast Wangiella dermatitidis as a model, we confirmed that ionizing radiation enhanced cell growth by increasing cell division and cell size. Using RNA-seq technology, we compared the transcriptomic profiles of the wild type and the melanin-deficient wdpks1 mutant under irradiation and non-irradiation conditions. It was found that more than 3000 genes were differentially expressed when these two strains were constantly exposed to a low dose of ionizing radiation and that half were regulated at least two fold in either direction. Functional analysis indicated that many genes for amino acid and carbohydrate metabolism and cell cycle progression were down-regulated and that a number of antioxidant genes and genes affecting membrane fluidity were up-regulated in both irradiated strains. However, the expression of ribosomal biogenesis genes was significantly up-regulated in the irradiated wild-type strain but not in the irradiated wdpks1 mutant, implying that melanin might help to contribute radiation energy for protein translation. Furthermore, we demonstrated that long-term exposure to low doses of radiation significantly increased survivability of both the wild-type and the wdpks1 mutant, which was correlated with reduced levels of reactive oxygen species (ROS), increased production of carotenoid and induced expression of genes encoding translesion DNA synthesis. Our results represent the first functional genomic study of how melanized fungal cells respond to low dose ionizing radiation and provide clues for the identification of biological processes, molecular pathways and individual genes

  1. Adaptation of the black yeast Wangiella dermatitidis to ionizing radiation: molecular and cellular mechanisms.

    PubMed

    Robertson, Kelly L; Mostaghim, Anahita; Cuomo, Christina A; Soto, Carissa M; Lebedev, Nikolai; Bailey, Robert F; Wang, Zheng

    2012-01-01

    Observations of enhanced growth of melanized fungi under low-dose ionizing radiation in the laboratory and in the damaged Chernobyl nuclear reactor suggest they have adapted the ability to survive or even benefit from exposure to ionizing radiation. However, the cellular and molecular mechanism of fungal responses to such radiation remains poorly understood. Using the black yeast Wangiella dermatitidis as a model, we confirmed that ionizing radiation enhanced cell growth by increasing cell division and cell size. Using RNA-seq technology, we compared the transcriptomic profiles of the wild type and the melanin-deficient wdpks1 mutant under irradiation and non-irradiation conditions. It was found that more than 3000 genes were differentially expressed when these two strains were constantly exposed to a low dose of ionizing radiation and that half were regulated at least two fold in either direction. Functional analysis indicated that many genes for amino acid and carbohydrate metabolism and cell cycle progression were down-regulated and that a number of antioxidant genes and genes affecting membrane fluidity were up-regulated in both irradiated strains. However, the expression of ribosomal biogenesis genes was significantly up-regulated in the irradiated wild-type strain but not in the irradiated wdpks1 mutant, implying that melanin might help to contribute radiation energy for protein translation. Furthermore, we demonstrated that long-term exposure to low doses of radiation significantly increased survivability of both the wild-type and the wdpks1 mutant, which was correlated with reduced levels of reactive oxygen species (ROS), increased production of carotenoid and induced expression of genes encoding translesion DNA synthesis. Our results represent the first functional genomic study of how melanized fungal cells respond to low dose ionizing radiation and provide clues for the identification of biological processes, molecular pathways and individual genes

  2. MMTF DISCOVERY OF GIANT IONIZATION CONES IN MR 2251-178: IMPLICATIONS FOR QUASAR RADIATIVE FEEDBACK

    SciTech Connect

    Kreimeyer, Kory; Veilleux, Sylvain E-mail: veilleux@astro.umd.edu

    2013-07-20

    We report the discovery of giant ionization cones in the 140 kpc nebula around quasar MR 2251-178 based on deep [O III] {lambda}5007/H{beta} and [N II] {lambda}6583/H{alpha} flux ratio maps obtained with the Maryland-Magellan Tunable Filter on the Baade-Magellan 6.5 m Telescope. These cones are aligned with the weak double-lobed radio source observed on smaller scale (<30 kpc). They have an opening angle {approx}120 Degree-Sign {+-} 10 Degree-Sign and subtend {approx}65%-90% of 4{pi} sr, where the uncertainty takes into account possible projection effects. The material in the outer ionization cones is matter-bounded, indicating that all ionizing photons emitted through the cones escape from the system. The quasar ionizing flux is {approx}2-3 times fainter outside of these cones, despite the largely symmetric geometry of the nebula in [O III]. Overall, adding up the contributions from both inside and outside the cones, we find that {approx}65%-95% of the quasar ionizing radiation makes its way out of the system. These results emphasize the need for line ratio maps to quantify the escape fraction of ionizing radiation from quasars and the importance of quasar radiative feedback on the intergalactic medium.

  3. A MULTIWAVELENGTH STUDY ON THE FATE OF IONIZING RADIATION IN LOCAL STARBURSTS

    SciTech Connect

    Hanish, D. J.; Oey, M. S.; Rigby, J. R.; Lee, J. C.; De Mello, D. F.

    2010-12-20

    The fate of ionizing radiation is vital for understanding cosmic ionization, energy budgets in the interstellar and intergalactic medium, and star formation rate indicators. The low observed escape fractions of ionizing radiation have not been adequately explained, and there is evidence that some starbursts have high escape fractions. We examine the spectral energy distributions (SEDs) of a sample of local star-forming galaxies, containing 13 local starburst galaxies and 10 of their ordinary star-forming counterparts, to determine if there exist significant differences in the fate of ionizing radiation in these galaxies. We find that the galaxy-to-galaxy variations in the SEDs are much larger than any systematic differences between starbursts and non-starbursts. For example, we find no significant differences in the total absorption of ionizing radiation by dust, traced by the 24 {mu}m, 70 {mu}m, and 160 {mu}m MIPS bands of the Spitzer Space Telescope, although the dust in starburst galaxies appears to be hotter than that of non-starburst galaxies. We also observe no excess ultraviolet flux in the Galaxy Evolution Explorer bands that could indicate a high escape fraction of ionizing photons in starburst galaxies. The small H{alpha} fractions of the diffuse, warm ionized medium (WIM) in starburst galaxies are apparently due to temporarily boosted H{alpha} luminosity within the star-forming regions themselves, with an independent, constant WIM luminosity. This independence of the WIM and starburst luminosities contrasts with WIM behavior in non-starburst galaxies and underscores our poor understanding of radiation transfer in both ordinary and starburst galaxies.

  4. Increased sensitivity to ionizing radiation by targeting the homologous recombination pathway in glioma initiating cells.

    PubMed

    Lim, Yi Chieh; Roberts, Tara L; Day, Bryan W; Stringer, Brett W; Kozlov, Sergei; Fazry, Shazrul; Bruce, Zara C; Ensbey, Kathleen S; Walker, David G; Boyd, Andrew W; Lavin, Martin F

    2014-12-01

    Glioblastoma is deemed the most malignant form of brain tumour, particularly due to its resistance to conventional treatments. A small surviving group of aberrant stem cells termed glioma initiation cells (GICs) that escape surgical debulking are suggested to be the cause of this resistance. Relatively quiescent in nature, GICs are capable of driving tumour recurrence and undergo lineage differentiation. Most importantly, these GICs are resistant to radiotherapy, suggesting that radioresistance contribute to their survival. In a previous study, we demonstrated that GICs had a restricted double strand break (DSB) repair pathway involving predominantly homologous recombination (HR) associated with a lack of functional G1/S checkpoint arrest. This unusual behaviour led to less efficient non-homologous end joining (NHEJ) repair and overall slower DNA DSB repair kinetics. To determine whether specific targeting of the HR pathway with small molecule inhibitors could increase GIC radiosensitivity, we used the Ataxia-telangiectasia mutated inhibitor (ATMi) to ablate HR and the DNA-dependent protein kinase inhibitor (DNA-PKi) to inhibit NHEJ. Pre-treatment with ATMi prior to ionizing radiation (IR) exposure prevented HR-mediated DNA DSB repair as measured by Rad51 foci accumulation. Increased cell death in vitro and improved in vivo animal survival could be observed with combined ATMi and IR treatment. Conversely, DNA-PKi treatment had minimal impact on GICs ability to resolve DNA DSB after IR with only partial reduction in cell survival, confirming the major role of HR. These results provide a mechanistic insight into the predominant form of DNA DSB repair in GICs, which when targeted may be a potential translational approach to increase patient survival. PMID:25017126

  5. Ionic Liquids and Ionizing Radiation: Reactivity of Highly Energetic Species

    SciTech Connect

    Wishart, J.F.

    2010-11-04

    Due to their unique properties, ionic liquids present many opportunities for basic research on the interactions of radiation with materials under conditions not previously available. At the same time, there are practical applied reasons for characterizing, understanding, and being able to predict how ionic-liquid-based devices and industrial-scale systems will perform under conditions of extreme reactivity, including radiation. This perspective discusses current issues in ionic liquid physical chemistry, provides a brief introduction to radiation chemistry, draws attention to some key findings in ionic liquid radiation chemistry, and identifies some current hot topics and new opportunities.

  6. Longevity, oxygen toxicity and radiation-enhanced resistance to oxygen in tribolium confusum

    SciTech Connect

    Lee, Y.J.

    1985-01-01

    Sublethal doses of ionizing radiation increase longevity in a variety of insects suggesting that irradiation may retard the age-dependent decline of physiological functions. There have been no systematic investigations of the response of irradiated populations to stress, however. The authors have demonstrated that resistance of adult flour beetles, Tribolium confusum, to oxygen poisoning declines progressively with age. They have examined oxygen resistance of irradiated populations of T. confusum as a function of age at irradiation, of time after irradiation, and of radiation dose and of dose-modifying factors. Shortly after gamma-irradiation, flour beetles exhibited a decline in resistance to oxygen toxicity. Then, about two weeks after irradiation, the LD/sub 50/ exposure time in pure oxygen was much greater than that of nonirradiated beetles, and this enhanced resistance persisted for about 6 months. The magnitude of the enhancement was a function of dose, decreased with increasing age at irradiation, and was modified by radiation factors. Sublethal irradiation under anoxia, at low dose rate, or with dose fractionation reduced the development of oxygen resistance to approximately the same degree that it reduced acute radiation lethality . Radiation-enhanced resistance to stress may be an important factor in the increased longevity of irradiated insects.

  7. Detection and quantification of 8-hydroxydeoxyguanosine adducts in peripheral blood of people exposed to ionizing radiation.

    PubMed Central

    Wilson, V L; Taffe, B G; Shields, P G; Povey, A C; Harris, C C

    1993-01-01

    Ionizing radiation produces a variety of damaging insults to nucleic acids, including the promutagenic lesion 8-hydroxydeoxyguanosine. In the present study, the 8-hydroxydeoxyguanosine content of peripheral blood leukocyte DNA isolated from individuals exposed to therapeutic doses of ionizing radiation was determined by a HPLC-coupled 32P-postlabeling assay. Peripheral blood leukocyte DNA from individuals irradiated with 180-200 cGy were observed to contain 2-4.5 times as much 8-hydroxydeoxyguanosine as that from unexposed individuals. These results were confirmed by the use of a HPLC-coupled electrochemical detection system. Thus, human exposure to ionizing radiation significantly increased the circulating leukocyte DNA content of 8-hydroxydeoxyguanosine. Images FIGURE 2. PMID:8319639

  8. Charge trapping in aligned single-walled carbon nanotube arrays induced by ionizing radiation exposure

    SciTech Connect

    Esqueda, Ivan S.; Cress, Cory D.; Che, Yuchi; Cao, Yu; Zhou, Chongwu

    2014-02-07

    The effects of near-interfacial trapping induced by ionizing radiation exposure of aligned single-walled carbon nanotube (SWCNT) arrays are investigated via measurements of gate hysteresis in the transfer characteristics of aligned SWCNT field-effect transistors. Gate hysteresis is attributed to charge injection (i.e., trapping) from the SWCNTs into radiation-induced traps in regions near the SWCNT/dielectric interface. Self-consistent calculations of surface-potential, carrier density, and trapped charge are used to describe hysteresis as a function of ionizing radiation exposure. Hysteresis width (h) and its dependence on gate sweep range are investigated analytically. The effects of non-uniform trap energy distributions on the relationship between hysteresis, gate sweep range, and total ionizing dose are demonstrated with simulations and verified experimentally.

  9. Targeting Notch to overcome radiation resistance

    PubMed Central

    Yahyanejad, Sanaz; Theys, Jan; Vooijs, Marc

    2016-01-01

    Radiotherapy represents an important therapeutic strategy in the treatment of cancer cells. However, it often fails to eliminate all tumor cells because of the intrinsic or acquired treatment resistance, which is the most common cause of tumor recurrence. Emerging evidences suggest that the Notch signaling pathway is an important pathway mediating radiation resistance in tumor cells. Successful targeting of Notch signaling requires a thorough understanding of Notch regulation and the context-dependent interactions between Notch and other therapeutically relevant pathways. Understanding these interactions will increase our ability to design rational combination regimens that are more likely to be safe and effective. Here we summarize the role of Notch in mediating resistance to radiotherapy, the different strategies to block Notch in cancer cells and how treatment scheduling can improve tumor response. Finally, we discuss a need for reliable Notch related biomarkers in specific tumors to measure pathway activity and to allow identification of a subset of patients who are likely to benefit from Notch targeted therapies. PMID:26713603

  10. Proceedings of a Meeting on Traceability for Ionizing Radiation Measurements

    NASA Astrophysics Data System (ADS)

    Heaton, H. T., II

    1982-02-01

    General concepts for traceability were presented from several perspectives. The national standards for radiation dosimetry, radioactivity measurements, and neutron measurements were described. Specific programs for achieving traceability to the national standards for radiation measurements in medical, occupational, and environmental applications were summarized.

  11. High and Low Doses of Ionizing Radiation Induce Different Secretome Profiles in a Human Skin Model

    SciTech Connect

    Zhang, Qibin; Matzke, Melissa M.; Schepmoes, Athena A.; Moore, Ronald J.; Webb-Robertson, Bobbie-Jo M.; Hu, Zeping; Monroe, Matthew E.; Qian, Weijun; Smith, Richard D.; Morgan, William F.

    2014-03-18

    It is postulated that secreted soluble factors are important contributors of bystander effect and adaptive responses observed in low dose ionizing radiation. Using multidimensional liquid chromatography-mass spectrometry based proteomics, we quantified the changes of skin tissue secretome – the proteins secreted from a full thickness, reconstituted 3-dimensional skin tissue model 48 hr after exposure to 3, 10 and 200 cGy of X-rays. Overall, 135 proteins showed statistical significant difference between the sham (0 cGy) and any of the irradiated groups (3, 10 or 200 cGy) on the basis of Dunnett adjusted t-test; among these, 97 proteins showed a trend of downregulation and 9 proteins showed a trend of upregulation with increasing radiation dose. In addition, there were 21 and 8 proteins observed to have irregular trends with the 10 cGy irradiated group either having the highest or the lowest level among all three radiated doses. Moreover, two proteins, carboxypeptidase E and ubiquitin carboxyl-terminal hydrolase isozyme L1 were sensitive to ionizing radiation, but relatively independent of radiation dose. Conversely, proteasome activator complex subunit 2 protein appeared to be sensitive to the dose of radiation, as rapid upregulation of this protein was observed when radiation doses were increased from 3, to 10 or 200 cGy. These results suggest that different mechanisms of action exist at the secretome level for low and high doses of ionizing radiation.

  12. Natural ionizing radiation exposure of the Spanish population.

    PubMed

    García-Talavera, M; Matarranz, J L; Martínez, M; Salas, R; Ramos, L

    2007-01-01

    This study investigates the exposure of the Spanish population to natural radiation sources. The annual average effective dose is estimated to be 1.6 mSv, taking into account contributions from cosmic radiation (18%), terrestrial gamma radiation (30%), radon and thoron inhalation (34%) and ingestion (18%). Cosmic radiation doses were calculated from town altitude data. Terrestrial gamma ray exposure outdoors were derived from the MARNA (natural gamma radiation map of Spain); indoor exposure was obtained multiplying the corresponding outdoor value by an experimentally calculated conversion factor. Radon doses were estimated from national surveys carried out throughout the country. To assess doses by ingestion, data from a detailed study on consumption habits in Spain and average radioactivity values from UNSCEAR have been considered. The variability in the exposures among individuals in the population has been explicitly taken into account in the assessment. PMID:17906301

  13. Ionization collection efficiencies of some ionization chambers in pulsed and continuous radiation beams.

    PubMed

    Holt, J G; Stanton, R E; Sell, R E

    1978-01-01

    The most commonly used method of calibrating high-energy photon or electron beams consists in converting cavity ionization to dose by the application of the appropriate Clambda or CE multipled by the 60Co correction factor. The correct interpretation of calibration data for pulsed photon or electron beams requires a knowledge of the charge collection efficiencies of the ionization chambers used. The results are presented of efficiency measurements for both pulsed and continuous beams made with these chambers: 0.6-cm3 Farmer, 0.5-cm3 Spokas, 3-cm3 Shonka, 1-cm3 PTW, and 1-cm3 Memorial pancake. The dependence of collection efficiency on collection voltage, dose rate, and dose per pulse is demonstrated. These results are shown to agree with Boag's formulas for collection efficiency. Attention is drawn to the fact that several kinds of dosimeters provide only minimal collection voltages for efficient collection of charge at high dose rates, especially in Linac electron beams. It is recommended to check the collection efficiency of chambers which are to be used at high dose rates, and a simple method for this purpose is described. PMID:683147

  14. Solar Irradiance Changes And Photobiological Effects At Earth's Surface Following Astrophysical Ionizing Radiation Events

    NASA Astrophysics Data System (ADS)

    Thomas, Brian; Neale, Patrick

    2016-01-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth for decades. Although there is some direct biological damage on the surface from redistributed radiation several studies have indicated that the greatest long term threat is from ozone depletion and subsequent heightened solar ultraviolet (UV) radiation. It is known that organisms exposed to this irradiation experience harmful effects such as sunburn and even direct damage to DNA, proteins, or other cellular structures. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In the present work, we employed a radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light). Using biological weighting functions we have considered a wide range of effects, including: erythema and skin cancer in humans; inhibition of photosynthesis in the diatom Phaeodactylum sp. and dinoflagellate Prorocentrum micans inhibition of carbon fixation in Antarctic phytoplankton; inhibition of growth of oat (Avena sativa L. cv. Otana) seedlings; and cataracts. We found that past work overestimated UVB irradiance, but that relative estimates for increase in exposure to DNA damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in

  15. The biobehavioral and neuroimmune impact of low-dose ionizing radiation

    PubMed Central

    York, Jason M; Blevins, Neil A; Meling, Daryl D; Peterlin, Molly B; Gridley, Daila S; Cengel, Keith A; Freund, Gregory G

    2011-01-01

    In the clinical setting, repeated exposures (10–30) to low-doses of ionizing radiation (≤ 200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 h and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice. PMID:21958477

  16. The biobehavioral and neuroimmune impact of low-dose ionizing radiation.

    PubMed

    York, Jason M; Blevins, Neil A; Meling, Daryl D; Peterlin, Molly B; Gridley, Daila S; Cengel, Keith A; Freund, Gregory G

    2012-02-01

    In the clinical setting, repeated exposures (10-30) to low-doses of ionizing radiation (≤200 cGy), as seen in radiotherapy for cancer, causes fatigue. Almost nothing is known, however, about the fatigue inducing effects of a single exposure to environmental low-dose ionizing radiation that might occur during high-altitude commercial air flight, a nuclear reactor accident or a solar particle event (SPE). To investigate the short-term impact of low-dose ionizing radiation on mouse biobehaviors and neuroimmunity, male CD-1 mice were whole body irradiated with 50 cGy or 200 cGy of gamma or proton radiation. Gamma radiation was found to reduce spontaneous locomotor activity by 35% and 36%, respectively, 6 h post irradiation. In contrast, the motivated behavior of social exploration was un-impacted by gamma radiation. Examination of pro-inflammatory cytokine gene transcripts in the brain demonstrated that gamma radiation increased hippocampal TNF-α expression as early as 4 h post-irradiation. This was coupled to subsequent increases in IL-1RA (8 and 12 h post irradiation) in the cortex and hippocampus and reductions in activity-regulated cytoskeleton-associated protein (Arc) (24 h post irradiation) in the cortex. Finally, restraint stress was a significant modulator of the neuroimmune response to radiation blocking the ability of 200 cGy gamma radiation from impairing locomotor activity and altering the brain-based inflammatory response to irradiation. Taken together, these findings indicate that low-dose ionizing radiation rapidly activates the neuroimmune system potentially causing early onset fatigue-like symptoms in mice. PMID:21958477

  17. The effects of low doses of ionizing radiation - A question of ethics

    SciTech Connect

    Tschaeche, A.N.

    1996-12-31

    Three ethical questions are asked and answered about the current state of affairs concerning how those in power manipulate public understanding of the effects of low doses of ionizing radiation. The questions are as follows: (1) Is it ethical to frighten people when you do not know that there is anything to be frightened of? (2) Is it ethical to be so conservative that resources are spent to solve a problem that may not exist? (3) Is it ethical not to tell the whole truth about the effects of low levels of ionizing radiation?

  18. Radiation resistance of non-0157:H7 Shiga Toxin-Producing Escherichia coli suspended in refrigerated catfish fillet meat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ionization (gamma) irradiation is a sustainable and important non-thermal treatment that has been very effective in controlling microorganisms and improving the safety and shelf life of foods. In the design of the food irradiation process, the knowledge of the radiation resistance of the target orga...

  19. Effects of ionizing radiations on a pharmaceutical compound, chloramphenicol

    NASA Astrophysics Data System (ADS)

    Varshney, L.; Patel, K. M.

    1994-05-01

    Chloramphenicol, a broad spectrum antibiotic, has been irradiated using Cobalt-60 γ radiation and electron beam at graded radiation doses upto 100 kGy. Several degradation products and free radicals are formed on irradiation. Purity, degradation products, free radicals, discolouration, crystallinity, solubility and entropy of radiation processing have been investigated. Aqueous solutions undergo extensive radiolysis even at low doses. Physico-chemical, microbiological and toxicological tests do not show significant degradation at sterilization dose. High performance liquid chromatography (HPLC), differential scanning calorimetry (DSC), UV-spectrophotometry, diffuse reflectance spectroscopy (DRS) and electron spin resonance spectroscopy (ESR) techniques were employed for the investigations.

  20. NBS1 knockdown by small interfering RNA increases ionizing radiation mutagenesis and telomere association in human cells

    NASA Technical Reports Server (NTRS)

    Zhang, Ying; Lim, Chang U K.; Williams, Eli S.; Zhou, Junqing; Zhang, Qinming; Fox, Michael H.; Bailey, Susan M.; Liber, Howard L.

    2005-01-01

    Hypomorphic mutations which lead to decreased function of the NBS1 gene are responsible for Nijmegen breakage syndrome, a rare autosomal recessive hereditary disorder that imparts an increased predisposition to development of malignancy. The NBS1 protein is a component of the MRE11/RAD50/NBS1 complex that plays a critical role in cellular responses to DNA damage and the maintenance of chromosomal integrity. Using small interfering RNA transfection, we have knocked down NBS1 protein levels and analyzed relevant phenotypes in two closely related human lymphoblastoid cell lines with different p53 status, namely wild-type TK6 and mutated WTK1. Both TK6 and WTK1 cells showed an increased level of ionizing radiation-induced mutation at the TK and HPRT loci, impaired phosphorylation of H2AX (gamma-H2AX), and impaired activation of the cell cycle checkpoint regulating kinase, Chk2. In TK6 cells, ionizing radiation-induced accumulation of p53/p21 and apoptosis were reduced. There was a differential response to ionizing radiation-induced cell killing between TK6 and WTK1 cells after NBS1 knockdown; TK6 cells were more resistant to killing, whereas WTK1 cells were more sensitive. NBS1 deficiency also resulted in a significant increase in telomere association that was independent of radiation exposure and p53 status. Our results provide the first experimental evidence that NBS1 deficiency in human cells leads to hypermutability and telomere associations, phenotypes that may contribute to the cancer predisposition seen among patients with this disease.

  1. The argument for a unified approach to non-ionizing radiation protection

    SciTech Connect

    Perala, R.A.; Rigden, G.J. ); Pfeffer, R.A. )

    1993-12-01

    In the next decade military equipment will be required to operate in severe electromagnetic environments. These environments are expected to contain most non-ionizing frequencies (D.C. to GHz), from hostile and/or non-hostile sources, and be severe enough to cause temporary upset or even catastrophic failure of electronic equipment. Over the past thirty years considerable emphasis has been placed on hardening critical systems to one or more of these non-ionizing radiation environments, the most prevalent being the nuclear-induced electromagnetic pulse (EMD). From this technology development there has evolved a hardening philosophy that applies to most of these non-ionizing radiation environments. The philosophy, which stresses the application of zonal shields plus penetration protection, can provide low-cost hardening against such diverse non-ionizing radiation as p-static, lightning, electromagnetic interference (EMI), EMP, high intensity radiated fields (HIRF), electromagnetic radiation (EMR), and high power microwaves (HPM). The objective in this paper is to describe the application of this philosophy to Army helicopters. The authors develop a unified specification complete with threat definitions and test methods which illustrates integration of EMP, lightning, and HIRF at the box qualification level. This paper is a summary of the effort documented in a cited reference.

  2. Immunomodulation of classical and non-classical HLA molecules by ionizing radiation.

    PubMed

    Gallegos, Cristina E; Michelin, Severino; Dubner, Diana; Carosella, Edgardo D

    2016-05-01

    Radiotherapy has been employed for the treatment of oncological patients for nearly a century, and together with surgery and chemotherapy, radiation oncology constitutes one of the three pillars of cancer therapy. Ionizing radiation has complex effects on neoplastic cells and on tumor microenvironment: beyond its action as a direct cytotoxic agent, tumor irradiation triggers a series of alterations in tumoral cells, which includes the de novo synthesis of particular proteins and the up/down-regulation of cell surface molecules. Additionally, ionizing radiation may induce the release of "danger signals" which may, in turn lead to cellular and molecular responses by the immune system. This immunomodulatory action of ionizing radiation highlights the importance of the combined use (radiotherapy plus immunotherapy) for cancer healing. Major histocompatibility complex antigens (also called Human Leukocyte Antigens, HLA in humans) are one of those molecules whose expression is modulated after irradiation. This review summarizes the modulatory properties of ionizing radiation on the expression of HLA class I (classical and non-classical) and class II molecules, with special emphasis in non-classical HLA-I molecules. PMID:27113815

  3. BRCA1 involved in regulation of Bcl-2 expression and apoptosis susceptibility to ionizing radiation

    NASA Astrophysics Data System (ADS)

    Wang, YanLing; Wang, Bing; Zhang, Hong; Li, Ning; Tanaka, Kaoru; Zhou, Xin; Chen, RuPing; Zhang, Xin

    2011-05-01

    BRCA1 has been proposed to be tightly linked to the resistance of tumor cells to ionizing radiation. The pathway leading to this phenomenon is not yet clear. In this work, we investigated the role of BRCA1 in the apoptosis regulation in response to carbon ion irradiation. We utilized three different cancer cell lines with various states for BRCA1 and p53 to identify the relationship between endogenous BRCA1 and the apoptosis-related genes, and determine whether p53 function would affect the role of BRCA1 in apoptosis regulation. By Western blot analysis, we found that Bax expressions were not significantly changed after irradiation in all of three cell lines. However, Bcl-2 expression showed an up-regulation by endogenous BRCA1 regardless of p53 status. Moreover, the changes in Bcl-2 protein were due to the increase in the transcriptional levels of Bcl-2 mRNA, based on real-time PCR assay. At the same time, BRCA1-deficient cells showed a greater apoptosis susceptibility to irradiation when compared with BRCA1-proficient cells. The results suggest that BRCA1 might exert p53-independent regulative activities for Bcl-2, which seems account for the low apoptosis susceptibility in BRCA1-proficient carcinomas.

  4. Interaction of free fatty acids with the erythrocyte membrane as affected by hyperthermia and ionizing radiation

    SciTech Connect

    Rybczynska, M.; Csordas, A. )

    1990-04-01

    The interference of hyperthermia and ionizing radiation, respectively, with the effects of capric (10:0), lauric (12:0), myristic (14:0), oleic (cis-18:1) and elaidic (trans-18:1) acids on the osmotic resistance of human erythrocytes was investigated. The results are summarized as follows: (A) not only at 37 degrees, but also at 42 and 47{degrees}C lauric acid (12:0) represents the minimum chain length for the biphasic behaviour of protecting against hypotonic hemolysis at a certain lower concentration range and hemolysis promotion at subsequent higher concentrations; (B) with increasing temperatures the protecting as well as the hemolytic effects occur at lower concentrations of the fatty acids; (C) the increase of temperature promotes the extent of hemolysis and reduces the extent of protection against hypotonic hemolysis; (D) Gamma-irradiation of erythrocytes selectively affects the concentration of oleic acid at which maximum protection against hypotonic hemolysis occurs, without altering the minimum concentration for 100% hemolysis.

  5. The oncogenic action of ionizing radiation on rat skin

    SciTech Connect

    Burns, F.J.; Garte, S.J.

    1990-01-01

    An extensive experiment involving approximately 400 rats exposed to the neon ion beam at the Bevalac in Berkeley, CA and to electrons is nearing completion. Progress is described in three areas corresponding to the specific aims of the proposal: (1) carcinogenesis and DNA strand breaks in rat skin following exposure by the neon ions or electrons; (2) oncogene activation in radiation-induced rat skin cancers; (3) DNA strand breaks in the epidermis as a function of radiation penetration. 59 refs., 4 tabs.

  6. Solar irradiance changes and photobiological effects at earth's surface following astrophysical ionizing radiation events.

    PubMed

    Thomas, Brian C; Neale, Patrick J; Snyder, Brock R

    2015-03-01

    Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the Tropospheric Ultraviolet and Visible (TUV) radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance but that relative estimates for increase in exposure to DNA-damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in very limited geographical areas; instead we found a net increase for most of the modeled time-space region. This result has implications for proposed climate changes associated with ionizing radiation events. PMID:25692406

  7. High frequency electromagnetic resistive instability in a Hall thruster under the effect of ionization

    SciTech Connect

    Singh, Sukhmander; Malik, Hitendra K.; Nishida, Yasushi

    2013-10-15

    Two types of high frequency electromagnetic resistive instabilities are found to occur in a Hall thruster plasma in the presence of collisions and ionization, out of which one of lower growth rate (called lower magnitude high frequency instability (LMHFI)) is sensitive to the axial component of the wave vector. The effects of ionization, collisions, and electron drift velocity on the growth rates of these instabilities are studied in greater details. The LMHFI grows faster in the presence of ionization but shows weaker dependence on the electrons' E(vector sign)×B(vector sign) drift, contrary to the case of other instability (called higher magnitude high frequency instability) which is sensitive to the azimuthal wave number and collisions.

  8. High frequency electromagnetic resistive instability in a Hall thruster under the effect of ionization

    NASA Astrophysics Data System (ADS)

    Singh, Sukhmander; Malik, Hitendra K.; Nishida, Yasushi

    2013-10-01

    Two types of high frequency electromagnetic resistive instabilities are found to occur in a Hall thruster plasma in the presence of collisions and ionization, out of which one of lower growth rate (called lower magnitude high frequency instability (LMHFI)) is sensitive to the axial component of the wave vector. The effects of ionization, collisions, and electron drift velocity on the growth rates of these instabilities are studied in greater details. The LMHFI grows faster in the presence of ionization but shows weaker dependence on the electrons' E→×B→ drift, contrary to the case of other instability (called higher magnitude high frequency instability) which is sensitive to the azimuthal wave number and collisions.

  9. [Effect of ionizing radiation on the living body].

    PubMed

    Kojima, Shuji

    2014-01-01

    Since the Fukushima nuclear plant accident following the great East Japan earthquake on March 11, 2011, we have been warned to be careful about possible radiation exposure almost every day in newspapers and on TV. Radioactive iodine ((131)I) and cesium ((134)Cs, (137)Cs) produced by nuclear reactions were released into the air during and after the accident, and have been scattered by the winds in Tohoku and in the Kanto district. Even today, 2 years after the accident, there is great public concern about possible pollution of foodstuffs and fishery products with radioactive cesium, not only in Japan, but also in other countries. On the other hand, decontamination work has been proceeding, including removal of contaminated soil near the accident site. Since the accident, many media reports have continued to tell us only that current dose levels of radiation are not dangerous to human health. But, many people are not satisfied with such vague statements, and want to understand the situation in more detail. So, it is important to provide basic education about the effects of radiation to the general public. I am a professor of the Department of Radiation Biosciences at Tokyo University of Science, and so I am very familiar with radiation and its dangers. So, in my lecture today, we would like to explain the effects of radiation and put the present situation into perspective, so that people will better understand the risks, and not be unnecessarily afraid. PMID:24492216

  10. Inactivation of thrombomodulin by ionizing radiation in a cell-free system: possible implications for radiation responses in vascular endothelium.

    PubMed

    Ross, Christopher C; MacLeod, Stewart L; Plaxco, Jason R; Froude, Jeffrey W; Fink, Louis M; Wang, Junru; Stites, Wesley E; Hauer-Jensen, Martin

    2008-04-01

    Normal tissue radiation injury is associated with loss of vascular thromboresistance, notably because of deficient levels of endothelial thrombomodulin (TM). TM is located on the luminal surface of most endothelial cells and has critical anticoagulant and anti-inflammatory functions. Chemical oxidation of a specific methionine residue (Met388) at the thrombin-binding site in TM reduces its main functional activity, i.e., the ability to activate protein C. We examined whether exposure to ionizing radiation affects TM in a similar manner. Full-length recombinant human TM, a construct of epidermal growth factor-like domains 4-6, which are involved in protein C activation, and a synthetic peptide containing the methionine of interest were exposed to gamma radiation in a cell-free system, i.e., a system not confounded by TM turnover or ectodomain shedding. The influence of radiation on functional activity was assessed with the protein C activation assay; formation of a TM-thrombin complex was assessed with surface plasmon resonance (Biacore), and oxidation of Met388 was assessed by HPLC and confirmed by mass spectroscopy. Exposure to radiation caused a dose-dependent reduction in protein C activation, impaired TM-thrombin complex formation, and oxidation of Met388. These results demonstrate that ionizing radiation adversely affects the TM molecule. Our findings may have relevance to normal tissue toxicity in clinical radiation therapy as well as to the development of radiation syndromes in the non-therapeutic radiation exposure setting. PMID:18363428

  11. Immune modulation by ionizing radiation and its implications for cancer immunotherapy.

    PubMed

    Friedman, Eric J

    2002-01-01

    Ionizing radiation exhibits immunomodulatory properties, which could portend a future collaboration of cancer immunotherapy with radiation therapy. The danger model of immunity describes antigen-specific cellular immunity engendered by an inflammatory milieu. Dendritic cells (DCs) are attracted to this microenvironment, undergoing maturation after internalizing apoptotic and necrotic cellular debris. Mature DCs mediate antigen-specific cellular immunity via presentation of processed antigen to T cells. Administration of radiation has been utilized in vitro and in vivo to create an inflammatory setting, via induction of apoptosis, necrosis, cell surface molecules, and secretory molecules. Caspase-mediated cellular apoptosis is induced by radiation thro ugh multiple signaling pathways. Radiation upregulates expression of immunomodulatory surface molecules (MHC, costimulatory molecules, adhesion molecules, death receptors, heat shock proteins) and secretory molecules (cytokines, inflammatory mediators) in tumor, stromal, and vascular endothelial cells. Results of animal studies indicate possible radiation-mediated modulation of tumor antigen-specific immunity. Experimental data could indicate that the radiation-induced danger microenvironment engenders a DC-mediated antigen-specific immune response. Further enhancement of radiation-mediated inflammation and cell death can be achieved via administration of radiosensitizing pharmaceuticals. Radiation-mediated immune modulation currently remains unquantified and poorly understood. A major research effort will be required to elucidate mechanisms of action. With a thorough understanding of this phenomenon, we believe that ionizing radiation could be optimized for use with cancer vaccines and generate tumor antigen-specific cellular immunity. PMID:12171547

  12. Alternative Physical Quality Parameters Influences Effectiveness of Lower Doses Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Yousif, Abubaker Ali; Bahari, Ismail Bin; Yasir, Muhamad Samudi

    2011-03-01

    It has been proved in many studied that the absorbed dose is not good physical quality parameter to quantify the radiation effects at lower doses. However relative biological effect (RBE) is still used as a major parameter of radiation effectiveness. Whereas linear energy transfer (LET) is inadequate physical parameter, therefore the weaknesses in using RBE-LET system for radiation protection have been investigated. Secondary data of V79 has reanalyzed to help complement the inadequacy current method in assessing cell inactivation at lower doses. Results of analysis show that the effectiveness of densely ionizing radiation is better quantified using mean free path (λ).

  13. Mass model of the LDEF satellite spacecraft and experiments for ionizing radiation analyses.

    PubMed

    Colborn, B L; Armstrong, T W

    1996-11-01

    A three-dimensional (3D) mass model of the LDEF spacecraft and selected experiments has been developed to allow the influence of material shielding on ionizing radiation measurements and analyses to be determined accurately. This computer model has been applied in a stand-alone mode to provide 3D shielding distributions around radiation dosimeters to aid data interpretation, and has been interfaced with radiation transport codes for a variety of different types of radiation predictions. This paper summarizes the methodology used, the level of detail incorporated, and some example model applications. PMID:11540514

  14. Role of Mn2+ and compatible solutes in the radiation resistance of thermophilic bacteria and archaea.

    PubMed

    Webb, Kimberly M; DiRuggiero, Jocelyne

    2012-01-01

    Radiation-resistant bacteria have garnered a great deal of attention from scientists seeking to expose the mechanisms underlying their incredible survival abilities. Recent analyses showed that the resistance to ionizing radiation (IR) in the archaeon Halobacterium salinarum is dependent upon Mn-antioxidant complexes responsible for the scavenging of reactive oxygen species (ROS) generated by radiation. Here we examined the role of the compatible solutes trehalose, mannosylglycerate, and di-myo-inositol phosphate in the radiation resistance of aerobic and anaerobic thermophiles. We found that the IR resistance of the thermophilic bacteria Rubrobacter xylanophilus and Rubrobacter radiotolerans was highly correlated to the accumulation of high intracellular concentration of trehalose in association with Mn, supporting the model of Mn(2+)-dependent ROS scavenging in the aerobes. In contrast, the hyperthermophilic archaea Thermococcus gammatolerans and Pyrococcus furiosus did not contain significant amounts of intracellular Mn, and we found no significant antioxidant activity from mannosylglycerate and di-myo-inositol phosphate in vitro. We therefore propose that the low levels of IR-generated ROS under anaerobic conditions combined with highly constitutively expressed detoxification systems in these anaerobes are key to their radiation resistance and circumvent the need for the accumulation of Mn-antioxidant complexes in the cell. PMID:23209374

  15. The protective effects of trace elements against side effects induced by ionizing radiation

    PubMed Central

    2015-01-01

    Trace elements play crucial role in the maintenance of genome stability in the cells. Many endogenous defense enzymes are containing trace elements such as superoxide dismutase and metalloproteins. These enzymes are contributing in the detoxification of reactive oxidative species (ROS) induced by ionizing radiation in the cells. Zinc, copper, manganese, and selenium are main trace elements that have protective roles against radiation-induced DNA damages. Trace elements in the free salt forms have protective effect against cell toxicity induced by oxidative stress, metal-complex are more active in the attenuation of ROS particularly through superoxide dismutase mimetic activity. Manganese-complexes in protection of normal cell against radiation without any protective effect on cancer cells are more interesting compounds in this topic. The aim of this paper to review the role of trace elements in protection cells against genotoxicity and side effects induced by ionizing radiation. PMID:26157675

  16. (Effects of ionizing radiation on scintillators and other particle detectors)

    SciTech Connect

    Proudfoot, J.

    1992-01-01

    It is my task to summarise the great variety of topics (covering a refreshing mix of physics, chemistry and technology) presented at this conference, which has focused on the effects of ionising radiation on scintillators and other particle detectors. One of the reasons and the central interest of many of the participants was the use of such detectors in experiments at two future large hadron colliders: the Superconducting Super Collider to be operating outside of Dallas in the United States by the turn of the decade and its European counterpart the Large Hadron Collider to be operating outside of Geneva in Switzerland on a similar time scale. These accelerators are the apple of the high energy physicist's eye.'' Their goal is to uncover the elusive Higgs particle and thereby set the cornerstone in our current knowledge of elementary particle interactions. This is the Quest, and from this lofty height the presentations rapidly moved on to the specific questions of experimental science: how such an experiment is carried out; why radiation damage is an issue; how radiation damage affects detectors; which factors affect radiation damage characteristics; which factors are not affected by radiation damage; and how better detectors may be constructed. These were the substance of this conference.

  17. 21 CFR 579.40 - Ionizing radiation for the treatment of poultry feed and poultry feed ingredients.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Ionizing radiation for the treatment of poultry feed and poultry feed ingredients. 579.40 Section 579.40 Food and Drugs FOOD AND DRUG ADMINISTRATION... § 579.40 Ionizing radiation for the treatment of poultry feed and poultry feed ingredients....

  18. 21 CFR 579.40 - Ionizing radiation for the treatment of poultry feed and poultry feed ingredients.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Ionizing radiation for the treatment of poultry feed and poultry feed ingredients. 579.40 Section 579.40 Food and Drugs FOOD AND DRUG ADMINISTRATION... § 579.40 Ionizing radiation for the treatment of poultry feed and poultry feed ingredients....

  19. Detailed Investigations of Interactions between Ionizing Radiation and Neutral Gases

    SciTech Connect

    Landers, Allen L

    2014-03-31

    We are investigating phenomena that stem from the many body dynamics associated with ionization of an atom or molecule by photon or charged particle. Our program is funded through the Department of Energy EPSCoR Laboratory Partnership Award in collaboration with Lawrence Berkeley National Laboratory. We are using variations on the well established COLTRIMS technique to measure ions and electrons ejected during these interactions. Photoionization measurements take place at the Advanced Light Source at LBNL as part of the ALS-COLTRIMS collaboration with the groups of Reinhard Dörner at Frankfurt and Ali Belkacem at LBNL. Additional experiments on charged particle impact are conducted locally at Auburn University where we are studying the dissociative molecular dynamics following interactions with either ions or electrons over a velocity range of 1 to 12 atomic units.

  20. Archway for Radiation and Micrometeorite Occurrence Resistance

    NASA Technical Reports Server (NTRS)

    Giersch, Louis R.

    2012-01-01

    The environmental conditions of the Moon require mitigation if a long-term human presence is to be achieved for extended periods of time. Radiation, micrometeoroid impacts, high-velocity debris, and thermal cycling represent threats to crew, equipment, and facilities. For decades, local regolith has been suggested as a candidate material to use in the construction of protective barriers. A thickness of roughly 3m is sufficient protection from both direct and secondary radiation from cosmic rays and solar protons; this thickness is sufficient to reduce radiation exposure even during solar flares. NASA has previously identified a need for innovations that will support lunar habitats using lightweight structures because the reduction of structural mass translates directly into additional up and down mass capability that would facilitate additional logistics capacity and increased science return for all mission phases. The development of non-pressurized primary structures that have synergy with the development of pressurized structures is also of interest. The use of indigenous or in situ materials is also a well-known and active area of research that could drastically improve the practicality of human exploration beyond low-Earth orbit. The Archway for Radiation and Micrometeorite Occurrence Resistance (ARMOR) concept is a new, multifunctional structure that acts as radiation shielding and micrometeorite impact shielding for long-duration lunar surface protection of humans and equipment. ARMOR uses a combination of native regolith and a deployed membrane jacket to yield a multifunctional structure. ARMOR is a robust and modular system that can be autonomously assembled on-site prior to the first human surface arrival. The system provides protection by holding a sufficiently thick (3 m) archshaped shell of local regolith around a central cavity. The regolith is held in shape by an arch-shaped jacket made of strong but deployable material. No regolith processing is

  1. Studies of oxidative degradation of polymers induced by ionizing radiation

    SciTech Connect

    Clough, R.L.; Gillen, K.T.

    1989-01-01

    Radiation effects on polymers in the presence of air are characterized by complicated phenomena such as dose-rate effects and post-irradiation degradation. These time-dependent effects can be understood in these terms: (1) features of the free radical chain-reaction chemistry underlying the oxidation, and (2) oxygen diffusion effects. A profiling technique has been developed to study heterogeneous degradation resulting from oxygen diffusion, and kinetic schemes have been developed to allow long-term aging predictions from short-term high dose-rate experiments. Low molecular weight additives which act either as free-radical scavengers or else as energy-scavengers are effective as stabilizers in radiation-oxidation environments. Non-radical oxidation mechanisms, involving species such as ozone, can also be important in the radiation-oxidation of polymers. 18 refs., 15 figs.

  2. Sperm quality and DNA damage in men from Jilin Province, China, who are occupationally exposed to ionizing radiation.

    PubMed

    Zhou, D D; Hao, J L; Guo, K M; Lu, C W; Liu, X D

    2016-01-01

    Long-term radiation exposure affects human health. Ionizing radiation has long been known to raise the risk of cancer. In addition to high doses of radiation, low-dose ionizing radiation might increase the risk of cardiovascular disease, lens opacity, and some other non-cancerous diseases. Low- and high-dose exposures to ionizing radiation elicit different signaling events at the molecular level, and may involve different response mechanisms. The health risks arising from exposure to low doses of ionizing radiation should be re-evaluated. Health workers exposed to ionizing radiation experience low-dose radiation and have an increased risk of hematological malignancies. Reproductive function is sensitive to changes in the physical environment, including ionizing radiation. However, data is scarce regarding the association between occupational radiation exposure and risk to human fertility. Sperm DNA integrity is a functional parameter of male fertility evaluation. Hence, we aimed to report sperm quality and DNA damage in men from Jilin Province, China, who were occupationally exposed to ionizing radiation. Sperm motility and normal morphology were significantly lower in the exposed compared with the non-exposed men. There was no statistically significant difference in sperm concentration between exposed and non-exposed men. The sperm DNA fragmentation index was significantly higher in the exposed than the non-exposed men. Chronic long-term exposure to low doses of ionizing radiation could affect sperm motility, normal morphology, and the sperm DNA fragmentation index in the Chinese population. Sperm quality and DNA integrity are functional parameters that could be used to evaluate occupational exposure to ionizing radiation. PMID:27050976

  3. Ionizing radiation and cancer risk: evidence from epidemiology.

    PubMed

    Ron, E

    1998-11-01

    Epidemiological studies provide the primary data on the carcinogenic effects of radiation in humans. Much of what is known has come from studies of the atomic bomb survivors, and to a lesser extent from patients receiving radiotherapy. These studies demonstrate that exposure to moderate to high doses of radiation increases the risk of cancer in most organs. For all solid cancers combined, cancers of the thyroid, breast and lung, and leukemia, risk estimates are fairly precise, and associations have been found at relatively low doses (<0.2 Gy). Associations between radiation and cancers of the salivary glands, stomach, colon, bladder, ovary, central nervous system and skin have also been reported, but the relationships are not as well quantified. Associations between radiation and cancers of the liver and esophagus, and to a lesser extent multiple myeloma and non-Hodgkin's lymphoma, have been reported in a few studies, but results are inconsistent. Chronic lymphocytic leukemia, Hodgkin's disease, and cancers of the pancreas, prostate, testis and cervix have rarely been linked to radiation exposure. A linear no-threshold model adequately describes the dose-response relationship for solid cancers, although at extremely high doses the risk appears to flatten out. Because few populations have been followed until the end of life, the temporal patterns of risk are not completely known. An increased risk, however, does continue for several decades. In contrast, radiation-related leukemias begin to occur shortly (2-3 years) after exposure and, at least in the A-bomb survivors, a linear-quadratic dose response seems to fit the data better than a pure linear model. Radiation does not act entirely in isolation. It can interact with other carcinogens, e.g. tobacco or chemotherapeutic agents, and with host factors such as age at exposure, gender or reproductive history. Interactions with medical interventions or with certain heritable mutations have also been suggested. While

  4. Proteomic Analysis of Low Dose Arsenic and Ionizing Radiation Exposure on Keratinocytes

    PubMed Central

    Berglund, Susanne R.; Santana, Alison R.; Li, Dan; Rice, Robert H.; Rocke, David M.; Goldberg, Zelanna

    2008-01-01

    Human exposure to arsenic and ionizing radiation occur environmentally at low levels. While the human health effects of arsenic and ionizing radiation have been examined separately, there is little information regarding their combined effects at doses approaching environmental levels. Arsenic toxicity may be affected by concurrent ionizing radiation especially given their known individual carcinogenic actions at higher doses. We found that keratinocytes responded to either low dose arsenic and/or low dose ionizing radiation exposure, resulting in differential proteomic expression based on 2DGE, immunoblotting and statistical analysis. Seven proteins were identified that passed a rigorous statistical screen for differential expression in 2DGE and also passed a strict statistical screen for follow-up immunoblotting. These included: α-enolase, epidermal-fatty acid binding protein, heat shock protein 27, histidine triad nucleotide-binding protein 1, lactate dehydrogenase A, protein disulfide isomerase precursor and S100A9. Four proteins had combined effects that were different than would be expected based on the response to either individual toxicant. These data demonstrate a possible reaction to the combined insult that is substantially different from that of either separate treatment. Several proteins had different responses than what has been seen from high dose exposures, adding to the growing literature suggesting that the cellular responses to low dose exposures are distinct. PMID:19294697

  5. Ionizing Radiation Impacts on Cardiac Differentiation of Mouse Embryonic Stem Cells

    PubMed Central

    Helm, Alexander; Arrizabalaga, Onetsine; Pignalosa, Diana; Schroeder, Insa S.; Durante, Marco

    2016-01-01

    Little is known about the effects of ionizing radiation on the earliest stages of embryonic development although it is well recognized that ionizing radiation is a natural part of our environment and further exposure may occur due to medical applications. The current study addresses this issue using D3 mouse embryonic stem cells as a model system. Cells were irradiated with either X-rays or carbon ions representing sparsely and densely ionizing radiation and their effect on the differentiation of D3 cells into spontaneously contracting cardiomyocytes through embryoid body (EB) formation was measured. This study is the first to demonstrate that ionizing radiation impairs the formation of beating cardiomyocytes with carbon ions being more detrimental than X-rays. However, after prolonged culture time, the number of beating EBs derived from carbon ion irradiated cells almost reached control levels indicating that the surviving cells are still capable of developing along the cardiac lineage although with considerable delay. Reduced EB size, failure to downregulate pluripotency markers, and impaired expression of cardiac markers were identified as the cause of compromised cardiomyocyte formation. Dysregulation of cardiac differentiation was accompanied by alterations in the expression of endodermal and ectodermal markers that were more severe after carbon ion irradiation than after exposure to X-rays. In conclusion, our data show that carbon ion irradiation profoundly affects differentiation and thus may pose a higher risk to the early embryo than X-rays. PMID:26506910

  6. Mammalian Tissue Response to Low Dose Ionizing Radiation: The Role of Oxidative Metabolism and Intercellular Communication

    SciTech Connect

    Azzam, Edouard I

    2013-01-16

    The objective of the project was to elucidate the mechanisms underlying the biological effects of low dose/low dose rate ionizing radiation in organs/tissues of irradiated mice that differ in their susceptibility to ionizing radiation, and in human cells grown under conditions that mimic the natural in vivo environment. The focus was on the effects of sparsely ionizing cesium-137 gamma rays and the role of oxidative metabolism and intercellular communication in these effects. Four Specific Aims were proposed. The integrated outcome of the experiments performed to investigate these aims has been significant towards developing a scientific basis to more accurately estimate human health risks from exposures to low doses ionizing radiation. By understanding the biochemical and molecular changes induced by low dose radiation, several novel markers associated with mitochondrial functions were identified, which has opened new avenues to investigate metabolic processes that may be affected by such exposure. In particular, a sensitive biomarker that is differentially modulated by low and high dose gamma rays was discovered.

  7. Volatile sulfur compounds in foods as a result of ionizing radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ionizing radiation improves food safety and extends shelf life by inactivating food-borne pathogens and spoilage microorganisms. However, irradiation may induce the development of an off-odor, particularly at high doses. The off-odor has been called “irradiation odor”. Substantial evidence suggests ...

  8. 21 CFR 579.22 - Ionizing radiation for treatment of animal diets.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Ionizing radiation for treatment of animal diets. 579.22 Section 579.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IRRADIATION IN THE PRODUCTION,...

  9. 21 CFR 579.22 - Ionizing radiation for treatment of animal diets.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Ionizing radiation for treatment of animal diets. 579.22 Section 579.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IRRADIATION IN THE PRODUCTION,...

  10. 21 CFR 579.22 - Ionizing radiation for treatment of animal diets.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Ionizing radiation for treatment of animal diets. 579.22 Section 579.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IRRADIATION IN THE PRODUCTION,...

  11. Possible standoff detection of ionizing radiation using high-power THz electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Nusinovich, Gregory S.; Sprangle, Phillip; Romero-Talamas, Carlos A.; Rodgers, John; Pu, Ruifeng; Kashyn, Dmytro G.; Antonsen, Thomas M., Jr.; Granatstein, Victor L.

    2012-06-01

    Recently, a new method of remote detection of concealed radioactive materials was proposed. This method is based on focusing high-power short wavelength electromagnetic radiation in a small volume where the wave electric field exceeds the breakdown threshold. In the presence of free electrons caused by ionizing radiation, in this volume an avalanche discharge can then be initiated. When the wavelength is short enough, the probability of having even one free electron in this small volume in the absence of additional sources of ionization is low. Hence, a high breakdown rate will indicate that in the vicinity of this volume there are some materials causing ionization of air. To prove this concept a 0.67 THz gyrotron delivering 200-300 kW power in 10 microsecond pulses is under development. This method of standoff detection of concealed sources of ionizing radiation requires a wide range of studies, viz., evaluation of possible range, THz power and pulse duration, production of free electrons in air by gamma rays penetrating through container walls, statistical delay time in initiation of the breakdown in the case of low electron density, temporal evolution of plasma structure in the breakdown and scattering of THz radiation from small plasma objects. Most of these issues are discussed in the paper.

  12. Using Ionizing Radiation Detectors. Module 11. Vocational Education Training in Environmental Health Sciences.

    ERIC Educational Resources Information Center

    Consumer Dynamics Inc., Rockville, MD.

    This module, one of 25 on vocational education training for careers in environmental health occupations, contains self-instructional materials on using ionizing radiation detectors. Following guidelines for students and instructors and an introduction that explains what the student will learn are three lessons: (1) naming and telling the function…

  13. 21 CFR 579.22 - Ionizing radiation for treatment of animal diets.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Ionizing radiation for treatment of animal diets. 579.22 Section 579.22 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS IRRADIATION IN THE PRODUCTION, PROCESSING, AND HANDLING OF ANIMAL FEED AND PET...

  14. Time- and dose-dependent effects of total-body ionizing radiation on muscle stem cells.

    PubMed

    Masuda, Shinya; Hisamatsu, Tsubasa; Seko, Daiki; Urata, Yoshishige; Goto, Shinji; Li, Tao-Sheng; Ono, Yusuke

    2015-04-01

    Exposure to high levels of genotoxic stress, such as high-dose ionizing radiation, increases both cancer and noncancer risks. However, it remains debatable whether low-dose ionizing radiation reduces cellular function, or rather induces hormetic health benefits. Here, we investigated the effects of total-body γ-ray radiation on muscle stem cells, called satellite cells. Adult C57BL/6 mice were exposed to γ-radiation at low- to high-dose rates (low, 2 or 10 mGy/day; moderate, 50 mGy/day; high, 250 mGy/day) for 30 days. No hormetic responses in proliferation, differentiation, or self-renewal of satellite cells were observed in low-dose radiation-exposed mice at the acute phase. However, at the chronic phase, population expansion of satellite cell-derived progeny was slightly decreased in mice exposed to low-dose radiation. Taken together, low-dose ionizing irradiation may suppress satellite cell function, rather than induce hormetic health benefits, in skeletal muscle in adult mice. PMID:25869487

  15. Strong effects of ionizing radiation from Chernobyl on mutation rates.

    PubMed

    Møller, Anders Pape; Mousseau, Timothy A

    2015-01-01

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material. PMID:25666381

  16. Strong effects of ionizing radiation from Chernobyl on mutation rates

    PubMed Central

    Møller, Anders Pape; Mousseau, Timothy A.

    2015-01-01

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material. PMID:25666381

  17. Strong effects of ionizing radiation from Chernobyl on mutation rates

    NASA Astrophysics Data System (ADS)

    Møller, Anders Pape; Mousseau, Timothy A.

    2015-02-01

    In this paper we use a meta-analysis to examine the relationship between radiation and mutation rates in Chernobyl across 45 published studies, covering 30 species. Overall effect size of radiation on mutation rates estimated as Pearson's product-moment correlation coefficient was very large (E = 0.67; 95% confidence intervals (CI) 0.59 to 0.73), accounting for 44.3% of the total variance in an unstructured random-effects model. Fail-safe calculations reflecting the number of unpublished null results needed to eliminate this average effect size showed the extreme robustness of this finding (Rosenberg's method: 4135 at p = 0.05). Indirect tests did not provide any evidence of publication bias. The effect of radiation on mutations varied among taxa, with plants showing a larger effect than animals. Humans were shown to have intermediate sensitivity of mutations to radiation compared to other species. Effect size did not decrease over time, providing no evidence for an improvement in environmental conditions. The surprisingly high mean effect size suggests a strong impact of radioactive contamination on individual fitness in current and future generations, with potentially significant population-level consequences, even beyond the area contaminated with radioactive material.

  18. Decoloration and detoxification of effluents by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Borrely, Sueli I.; Morais, Aline V.; Rosa, Jorge M.; Badaró-Pedroso, Cintia; da Conceição Pereira, Maria; Higa, Marcela C.

    2016-07-01

    Three distinct textile samples were investigated for color and toxicity (S1-chemical/textile industry; S2-final textile effluent; S3 - standard textile produced effluent-untreated blue). Radiation processing of these samples were carried out at Dynamitron Electron Beam Accelerator and color and toxicity removal were determined: color removal by radiation was 96% (40 kGy, S1); 55% (2.5 kGy, S2) and 90% (2.5 kGy, S3). Concerning toxicity assays, Vibrio fischeri luminescent bacteria demonstrated higher reduction after radiation than the other systems: removal efficiencies were 33% (20 kGy, S1); 55% (2.5 kGy, S2) and 33% (2.5 kGy, S3). Daphnia similis and Brachionus plicatilis fitted well for S3 effluents. Hard toxic volumes into biological treatment plant may be avoided if radiation would be previously applied in a real plant. Results reveled how indispensable is to run toxicity to more than one living-organism.

  19. The effects of low-dose ionizing radiation in the activated rat basophilic leukemia (RBL-2H3) mast cells.

    PubMed

    Joo, Hae Mi; Nam, Seon Young; Yang, Kwang Hee; Kim, Cha Soon; Jin, Young Woo; Kim, Ji Young

    2012-08-10

    Mast cells play important roles in many biological responses, such as those during allergic diseases and inflammatory disorders. Although laser and UV irradiation have immunosuppressive effects on inflammatory diseases by suppressing mast cells, little is known about the effects of γ-ionizing radiation on mast cells. In this study, we investigated the effects of γ-ionizing radiation on RBL-2H3 cells, a convenient model system for studying regulated secretion by mast cells. Low-dose radiation (<0.1 gray (Gy)) did not induce cell death, but high-dose radiation (>0.5 Gy) induced apoptosis. Low-dose ionizing radiation significantly suppressed the release of mediators (histamine, β-hexosaminidase, IL-4, and tumor necrosis factor-α) from immunoglobulin E (IgE)-sensitized RBL-2H3 cells. To determine the mechanism of mediator release inhibition by ionizing radiation, we examined the activation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, PKCs, and MAPK, and intracellular free calcium concentrations ([Ca(2+)](i)). The phosphorylation of signaling molecules following stimulation of high-affinity IgE receptor I (FcεRI) was specifically inhibited by low-dose ionizing radiation (0.01 Gy). These results were due to the suppression of FcεRI expression by the low-dose ionizing radiation. Therefore, low-dose ionizing radiation (0.01 Gy) may function as a novel inhibitor of mast cell activation. PMID:22700973

  20. Radiation resistance of endohedral metallofullerenols under neutron irradiation

    NASA Astrophysics Data System (ADS)

    Szhogina, A. A.; Shilin, V. A.; Sedov, V. P.; Lebedev, V. T.

    2016-07-01

    The endohedral metallofullerenols Me@C2 n (OH)38-40 + C2 n (OH)38-40 ( Me = Tb, Sc, Gd, Fe, Pr, Mo) have been obtained and their radiation resistance under irradiation by a neutron flux of 8 × 1013 cm-2 s-1 has been studied. The factors affecting the radiation resistance of endohedral metallofullerenols are discussed.

  1. Salt shield: intracellular salts provide cellular protection against ionizing radiation in the halophilic archaeon, Halobacterium salinarum NRC-1.

    PubMed

    Kish, A; Kirkali, G; Robinson, C; Rosenblatt, R; Jaruga, P; Dizdaroglu, M; DiRuggiero, J

    2009-05-01

    The halophilic archaeon Halobacterium salinarum NRC-1 was used as a model system to investigate cellular damage induced by exposure to high doses of ionizing radiation (IR). Oxidative damages are the main lesions from IR and result from free radicals production via radiolysis of water. This is the first study to quantify DNA base modification in a prokaryote, revealing a direct relationship between yield of DNA lesions and IR dose. Most importantly, our data demonstrate the significance of DNA radiation damage other than strand breaks on cell survival. We also report the first in vivo evidence of reactive oxygen species scavenging by intracellular halides in H. salinarum NRC-1, resulting in increased protection against nucleotide modification and carbonylation of protein residues. Bromide ions, which are highly reactive with hydroxyl radicals, provided the greatest protection to cellular macromolecules. Modified DNA bases were repaired in 2 h post irradiation, indicating effective DNA repair systems. In addition, measurements of H. salinarum NRC-1 cell interior revealed a high Mn/Fe ratio similar to that of Deinococcus radiodurans and other radiation-resistant microorganisms, which has been shown to provide a measure of protection for proteins against oxidative damage. The work presented here supports previous studies showing that radiation resistance is the product of mechanisms for cellular protection and detoxification, as well as for the repair of oxidative damage to cellular macromolecules. The finding that not only Mn/Fe but also the presence of halides can decrease the oxidative damage to DNA and proteins emphasizes the significance of the intracellular milieu in determining microbial radiation resistance. PMID:19452594

  2. Molecular Data for a Biochemical Model of DNA Radiation Damage: Electron Impact Ionization and Dissociative Ionization of DNA Bases and Sugar-Phosphate Backbone

    NASA Technical Reports Server (NTRS)

    Dateo, Christopher E.; Fletcher, Graham D.

    2004-01-01

    As part of the database for building up a biochemical model of DNA radiation damage, electron impact ionization cross sections of sugar-phosphate backbone and DNA bases have been calculated using the improved binary-encounter dipole (iBED) model. It is found that the total ionization cross sections of C3'- and C5'-deoxyribose-phospate, two conformers of the sugar-phosphate backbone, are close to each other. Furthermore, the sum of the ionization cross sections of the separate deoxyribose and phosphate fragments is in close agreement with the C3'- and C5'-deoxyribose-phospate cross sections, differing by less than 10%. Of the four DNA bases, the ionization cross section of guanine is the largest, then in decreasing order, adenine, thymine, and cytosine. The order is in accordance with the known propensity of oxidation of the bases by ionizing radiation. Dissociative ionization (DI), a process that both ionizes and dissociates a molecule, is investigated for cytosine. The DI cross section for the formation of H and (cytosine-Hl)(+), with the cytosine ion losing H at the 1 position, is also reported. The threshold of this process is calculated to be 17.1 eV. Detailed analysis of ionization products such as in DI is important to trace the sequential steps in the biochemical process of DNA damage.

  3. Evaluation of delayed effects of ionizing radiation: an historical perspective.

    PubMed

    Stewart, A M

    1991-01-01

    It is widely assumed that after the bombing of Hiroshima and Nagasaki there were no lasting effects of the acute injuries (which included extensive damage to blood forming tissues by the radiation) or the massively high death rate (which was caused by environmental effects of the blast as well as personal injuries). However, close inspection of the dose response curves for non-cancer deaths has shown that this could be a false impression caused by one effect of marrow aplasia being confused with leukemia (defective erythropoiesis) and a second effect being confused with early selection in favor of general fitness (defective immune responses). Possible consequences of such confusion (for cancer risk coefficients) are discussed in relation to what is known about late effects of prenatal x-rays and occupational exposures to radiation. PMID:1805618

  4. Radiation resistance of primary clonogenic blasts from children with acute lymphoblastic leukemia

    SciTech Connect

    Uckun, F.M. Childrens Cancer Group, Arcadia, CA ); Aeppli, D.; Song, C.W. )

    1993-11-15

    Detailed comparative analyses of the radiation sensitivity of primary clonogenic blasts from children with acute lymphoblastic leukemia (ALL) were performed to achieve a better understanding of clinical radiation resistance in ALL. The radiation sensitivity of primary clonogenic blasts from 74 children with newly diagnosed ALL was analyzed using leukemic progenitor cell (LPC) assays. Primary bone marrow blasts from all 74 patients were exposed to ionizing radiation and subsequently assayed for LPC-derived blast colony formation. Radiation survival curves of LPC were constructed for each of the newly diagnosed patients using computer programs for the single-hit multitarget as well as the linear quadratic models of cell survival. A marked interpatient variation in intrinsic radiation sensitivity was observed between LPC populations. The SF[sub 2] values ranged from 0.01 to 1.00. Patients were divided into groups according to their sex, age, WBC at diagnosis, cell cycle distribution of leukemic blasts, and immunophenotype. Only immunophenotype provided a significant correlation with the intrinsic radiation sensitivity of LPC. Patients with B-lineage ALL had higher SF[sub 2] and smaller [alpha] values than T-lineage ALL patients, consistent with greater intrinsic radiation resistance at the level of LPC. Notably, 43% of B-lineage ALL cases, but only 27% of T-lineage ALL cases had LPC with SF[sub 2] [ge] 0.5. Similarly, 66% of B-lineage ALL cases, but only 37% of T-lineage ALL cases had LPC with [alpha] values [le] 0.4 Gy[sup [minus]1]. Combining the two indicators of radiation resistance, they found that only 34% of the B-lineage ALL patients had none of the two parameters in the respective critical regions, while 63% of the T-lineage patients had none. In multivariate analyses, the immunophenotypic B-lineage affiliation was the only significant predictor of radiation resistance at the level of LPC. 42 refs., 1 fig., 2 tabs.

  5. Overview of atmospheric ionizing radiation (AIR) research: SST-present

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Goldhagen, P.; Rafnsson, V.; Clem, J. M.; De Angelis, G.; Friedberg, W.

    2003-01-01

    The Supersonic Transport (SST) program, proposed in 1961, first raised concern for the exposure of pregnant occupants by solar energetic particles (SEP), and neutrons were suspected to have a main role in particle propagation deep into the atmosphere. An eight-year flight program confirmed the role of SEP as a significant hazard and of the neutrons as contributing over half of the galactic cosmic ray exposures, with the largest contribution from neutrons above 10 MeV. The FAA Advisory Committee on the Radiobiological Aspects of the SST provided operational requirements. The more recent lowering of ICRP-recommended exposure limits (1990) with the classification of aircrew as "radiation workers" renewed interest in GCR background exposures at commercial flight altitudes and stimulated epidemiological studies in Europe, Japan, Canada and the USA. The proposed development of a High Speed Civil Transport (HSCT) required validation of the role of high-energy neutrons, and this resulted in ER-2 flights at solar minimum (June 1997) and studies on effects of aircraft materials on interior exposures. Recent evaluation of health outcomes of DOE nuclear workers resulted in legislation for health compensation in year 2000 and recent European aircrew epidemiological studies of health outcomes bring renewed interest in aircraft radiation exposures. As improved radiation models become available, it is imperative that a corresponding epidemiological program of US aircrew be implemented. Published by Elsevier Ltd on behalf of COSPAR.

  6. Overview of Atmospheric Ionizing Radiation (AIR) Research: SST - Present

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Goldhagen, P.; Rafnsson, V.; Clem, J. M.; DeAngelis, G.; Friedberg, W.

    2002-01-01

    The Supersonic Transport (SST) program, proposed in 1961, first raised concern for the exposure of pregnant occupants by solar energetic particles (SEP), and neutrons were suspected to have a main role in particle propagation deep into the atmosphere. An eight-year flight program confirmed the role of SEP as a significant hazard and of the neutrons as contributing over half of the galactic cosmic ray (GCR) exposures, with the largest contribution from neutrons above 10 MeV. The FAA Advisory Committee on the Radiobiological Aspects of the SST provided operational requirements. The more recent (1990) lowering of recommended exposure limits by the International Commission on Radiological Protection with the classification of aircrew as "radiation workers" renewed interest in GCR background exposures at commercial flight altitudes and stimulated epidemiological studies in Europe, Japan, Canada and the USA. The proposed development of a High Speed Civil Transport (HSCT) required validation of the role of high-energy neutrons, and this resulted in ER-2 flights at solar minimum (June 1997) and studies on effects of aircraft materials on interior exposures. Recent evaluation of health outcomes of DOE nuclear workers resulted in legislation for health compensation in year 2000 and recent European aircrew epidemiological studies of health outcomes bring renewed interest in aircraft radiation exposures. As improved radiation models become available, it is imperative that a corresponding epidemiological program of US aircrew be implemented.

  7. Overview of Atmospheric Ionizing Radiation (AIR) research: SST-present

    NASA Astrophysics Data System (ADS)

    Wilson, J.; Goldhagen, P.; Rafnson, V.; Clem, J.; Deangelis, G.

    The Super Sonic Transport (SST) program, proposed in 1961, first raised concern for the exposure of pregnant passengers and crew by solar energetic particles (SEP), and neutrons were suspected to have a main role in effects due to particle propagation deep into the atmosphere. An eight-year flight program confirmed the role of SEP as a significant hazard and of the neutrons as contributing over half of the galactic cosmic ray exposures, with the largest contribution from neutrons above 10 MeV. The FAA Standing Committee provided recommendations on SST radiobiological issues and operational requirements. The lowering of ICRP-recommended exposure limits (1990) with the classification of aircrew as "radiation workers" renewed interest in GCR background exposures at commercial flight altitudes and stimulated epidemiological studies in Europe, Japan, Canada and the USA. The proposed development of a High Speed Civil Transport (HSCT) required validation of the role of high-energy neutrons, and this resulted in ER-2 flights at solar minimum (June 1997) and studies of effects of aircraft materials on interior exposures. Recent evaluation of health outcomes of DOE nuclear workers resulted in legislation for health compensation in 2000 and more recent European aircrew epidemiological studies of health outcomes brings renewed interest in aircraft radiation exposures. As improved radiation models become available, it is imperative that a corresponding epidemiological program of US aircrew be implemented.

  8. Overview of atmospheric ionizing radiation (AIR) Research: SST-present

    NASA Astrophysics Data System (ADS)

    Wilson, J. W.; Goldhagen, P.; Rafnsson, V.; Clem, J. M.; De Angelis, G.; Friedberg, W.

    The Supersonic Transport (SST) program proposed in 1961, first raised concern for the exposure of pregnant occupants by solar energetic particles (SEP), and neutrons were suspected to have a main role in particle propagation deep into the atmosphere. An eight-year flight program confirmed the role of SEP as a significant hazard and of the neutrons as contributing over half of the galactic cosmic ray exposures, with the largest contribution from neutrons above 10 MeV. The FAA Advisory Committee on the Radiobiological Aspects of the SST provided operational requirements. The more recent lowering of ICRP-recommended exposure limits 1990 with the classification of aircrew as "radiation workers" renewed interest in GCR background exposures at commercial flight altitudes and stimulated epidemiological studies in Europe, Japan, Canada and the USA. The proposed development of a High Speed Civil Transport (HSCT) required validation of the role of high-energy neutrons, and this resulted in ER-2 flights at solar minimum June 1997 and studies on effects of aircraft materials on interior exposures. Recent evaluation of health outcomes of DOE nuclear workers resulted in legislation for health compensation in year 2000 and recent European aircrew epidemiological studies of health outcomes bring renewed interest in aircraft radiation exposures. As improved radiation models become available, it is imperative that a corresponding epidemiological program of US aircrew be implemented.

  9. Claims based on exposure to ionizing radiation (prostate cancer and any other cancer)--VA. Final rule.

    PubMed

    1998-09-24

    This document amends the Department of Veterans Affairs (VA) adjudication regulations concerning compensation for diseases claimed to be the result of exposure to ionizing radiation. This amendment implements a decision by the Secretary of Veterans Affairs that, based on all evidence currently available to him, prostate cancer and any other cancers may be induced by ionizing radiation. The intended effect of this action is to relieve veterans, or their survivors, seeking benefits under the provisions of the Veterans' Dioxin and Radiation Exposure Compensation Standards Act of the burden of having to submit evidence that a veteran's prostate cancer or any other cancer may have been induced by ionizing radiation. PMID:10185808

  10. SU11248 (Sunitinib) Sensitizes Pancreatic Cancer to the Cytotoxic Effects of Ionizing Radiation

    SciTech Connect

    Cuneo, Kyle C.; Geng Ling; Fu, Allie; Orton, Darren; Hallahan, Dennis E.; Chakravarthy, Anuradha Bapsi

    2008-07-01

    Purpose: SU11248 (sunitinib) is a small-molecule tyrosine kinase inhibitor which targets VEGFR and PDGFR isoforms. In the present study, the effects of SU11248 and ionizing radiation on pancreatic cancer were studied. Methods and Materials: For in vitro studies human pancreatic adenocarcinoma cells lines were treated with 1 {mu}M SU11248 1 h before irradiation. Western blot analysis was used to determine the effect of SU11248 on radiation-induced signal transduction. To determine if SU11248 sensitized pancreatic cancer to the cytotoxic effects of ionizing radiation, a clonogenic survival assay was performed using 0-6 Gy. For in vivo assays, CAPAN-1 cells were injected into the hind limb of nude mice for tumor volume and proliferation studies. Results: SU11248 attenuated radiation-induced phosphorylation of Akt and ERK at 0, 5, 15, and 30 min. Furthermore, SU11248 significantly reduced clonogenic survival after treatment with radiation (p < 0.05). In vivo studies revealed that SU11248 and radiation delayed tumor growth by 6 and 10 days, respectively, whereas combined treatment delayed tumor growth by 30 days. Combined treatment with SU11248 and radiation further attenuated Brdu incorporation by 75% (p = 0.001) compared to control. Conclusions: SU11248 (sunitinib) sensitized pancreatic cancer to the cytotoxic effects of radiation. This compound is promising for future clinical trials with chemoradiation in pancreatic cancer.

  11. Determination of the ionization potentials of security-relevant substances with single photon ionization mass spectrometry using synchrotron radiation.

    PubMed

    Schramm, E; Mühlberger, F; Mitschke, S; Reichardt, G; Schulte-Ladbeck, R; Pütz, M; Zimmermann, R

    2008-02-01

    Several ionization potentials (IPs) of security relevant substances were determined with single photon ionization time of flight mass spectrometry (SPI-TOFMS) using monochromatized synchrotron radiation from the "Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung" (BESSY). In detail, the IPs of nine explosives and related compounds, seven narcotics and narcotics precursors, and one chemical warfare agent (CWA) precursor were determined, whereas six IPs already known from the literature were verified correctly. From seven other substances, including one CWA precursor, the IP could not be determined as the molecule ion peak could not be detected. For these substances the appearance energy (AE) of a main fragment was determined. The analyzed security-relevant substances showed IPs significantly below the IPs of common matrix compounds such as nitrogen and oxygen. Therefore, it is possible to find photon energies in between, whereby the molecules of interest can be detected with SPI in very low concentrations due to the shielding of the matrix. All determined IPs except the one of the explosive EGDN were below 10.5 eV. Hence, laser-generated 118 nm photons can be applied for detecting almost all security-relevant substances by, e.g., SPI-TOFMS. PMID:18284801

  12. Atmospheric Ionizing Radiation and the High Speed Civil Transport. Chapter 1

    NASA Technical Reports Server (NTRS)

    Maiden, D. L.; Wilson, J. W.; Jones, I. W.; Goldhagen, P.

    2003-01-01

    Atmospheric ionizing radiation is produced by extraterrestrial radiations incident on the Earth's atmosphere. These extraterrestrial radiations are of two sources: ever present galactic cosmic rays with origin outside the solar system and transient solar particle events that are at times very intense events associated with solar activity lasting several hours to a few days. Although the galactic radiation penetrating through the atmosphere to the ground is low in intensity, the intensity is more than two orders of magnitude greater at commercial aircraft altitudes. The radiation levels at the higher altitudes of the High Speed Civil Transport (HSCT) are an additional factor of two higher. Ionizing radiation produces chemically active radicals in biological tissues that alter the cell function or result in cell death. Protection standards against low levels of ionizing radiation are based on limitation of excess cancer mortality or limitation of developmental injury resulting in permanent damage to the offspring during pregnancy. The crews of commercial air transport operations are considered as radiation workers by the EPA, the FAA, and the International Commission on Radiological Protection (ICRP). The annual exposures of aircrews depend on the latitudes and altitudes of operation and flight time. Flight hours have significantly increased since deregulation of the airline industry in the 1980's. The FAA estimates annual subsonic aircrew exposures to range from 0.2 to 9.1 mSv compared to 0.5 mSv exposure of the average nuclear power plant worker in the nuclear industry. The commercial aircrews of the HSCT may receive exposures above recently recommended allowable limits for even radiation workers if flying their allowable number of flight hours. An adequate protection philosophy for background exposures in HSCT commercial airtraffic cannot be developed at this time due to current uncertainty in environmental levels. In addition, if a large solar particle event

  13. RADIONUCLIDE IONIZATION IN PROTOPLANETARY DISKS: CALCULATIONS OF DECAY PRODUCT RADIATIVE TRANSFER

    SciTech Connect

    Cleeves, L. Ilsedore; Adams, Fred C.; Bergin, Edwin A.; Visser, Ruud

    2013-11-01

    We present simple analytic solutions for the ionization rate ζ{sub SLR} arising from the decay of short-lived radionuclides (SLRs) within protoplanetary disks. We solve the radiative transfer problem for the decay products within the disk, and thereby allow for the loss of radiation at low disk surface densities; energy loss becomes important outside R ∼> 30 AU for typical disk masses M{sub g} = 0.04 M{sub ☉}. Previous studies of chemistry/physics in these disks have neglected the impact of ionization by SLRs, and often consider only cosmic rays (CRs), because of the high CR-rate present in the interstellar medium. However, recent work suggests that the flux of CRs present in the circumstellar environment could be substantially reduced by relatively modest stellar winds, resulting in severely modulated CR ionization rates, ζ{sub CR}, equal to or substantially below that of SLRs (ζ{sub SLR} ∼< 10{sup –18} s{sup –1}). We compute the net ionizing particle fluxes and corresponding ionization rates as a function of position within the disk for a variety of disk models. The resulting expressions are especially simple for the case of vertically Gaussian disks (frequently assumed in the literature). Finally, we provide a power-law fit to the ionization rate in the midplane as a function of gas disk surface density and time. Depending on location in the disk, the ionization rates by SLRs are typically in the range ζ{sub SLR} ∼ (1-10) × 10{sup –19} s{sup –1}.

  14. Computer model to simulate ionizing radiation effects correlates with experimental data

    NASA Astrophysics Data System (ADS)

    Perez-Poch, Antoni

    Exposure to radiation from high energy protons and particles with ionizing properties is a major challenge for long-term space missions. The specific effect of such radiation on hematopoietic cells is still not fully understood. A number of experiments have been conducted on ground and in space. Those experiments on one hand, measure the extent of damage on blood markers. On the other hand, they intend to quantify the correlation between dose and energy from the radiation particles, with their ability to impair the hematopoietic stem and progenitor function. We present a computer model based on a neural network that intends to assess the relationship between dose, energy and number of hits on a particular cell, to the damage incurred to the human marrow cells. Calibration of the network is performed with the existing experimental data available in bibliography. Different sources of ionizing radiation at different doses (0-90 cGy) and along different patterns of a long-term exposure scenarios are simulated. Results are shown for a continuous variation of doses and are compared with specific data available in the literature. Some predictions are inferred for long-term scenarios of spaceflight, and the risk of jeopardizing a mission due to a major disfunction of the bone marrow is calculated. The method has proved successful in reproducing specific experimental data. We also discuss the significance and validity of the predicted ionizing radiation effects in situations such as long-term missions for a continuous range of dose.

  15. Resistance of Clostridium perfringens Type A Spores to γ-Radiation

    PubMed Central

    Midura, T. F.; Kempe, L. L.; Graikoski, J. T.; Milone, N. A.

    1965-01-01

    The radiation resistance of the spores of a classical strain and of an atypical, heat-resistant strain of Clostridium perfringens was determined. Spores were produced in Ellner's and in a Trypticase broth medium. Approximately 106 viable spores per milliliter were suspended in 0.06 m phosphate buffer and irradiated with γ rays from cobalt-60; the survivors were counted in Tryptone-yeast extract-agar by the Prickett-tube technique. Radiation D values for spores of the atypical strain in phosphate buffer and in cooked-meat broth were 0.23 and 0.30 Mrad, respectively, and the D value of the classical strain was 0.25 Mrad in phosphate buffer. Spores of the classical and atypical strains of C. perfringens type A are characterized by differences in heat resistance; yet, all strains tested demonstrated similar radiation resistance. Also, the spores were more resistant to ionizing radiation in cooked-meat broth than in phosphate buffer. PMID:14325887

  16. Recollections on Sixty Years of NBS Ionizing Radiation Programs for Energetic X Rays and Electrons1

    PubMed Central

    Koch, H. William

    2006-01-01

    These recollections are on ionizing radiation programs at the National Bureau of Standards (NBS) that started in 1928 and ended in 1988 when NBS became the National Institute of Standards and Technology (NIST). The independent Council on Ionizing Radiation Measurements and Standards (CIRMS) was formed in 1992. This article focuses on how measurements and standards for x rays, gamma rays, and electrons with energies above 1 MeV began at NBS and how they progressed. It also suggests how the radiation processors of materials and foods, the medical radiographic and radiological industries, and the radiological protection interests of the government (including homeland security) represented in CIRMS can benefit from NIST programs. PMID:27274947

  17. Choosing populations to study the health effects of low-dose ionizing radiation.

    PubMed Central

    Dreyer, N A; Loughlin, J E; Friedlander, E R; Clapp, R W; Fahey, F H

    1981-01-01

    In January 1978, the United States Congress requested information about the utility of additional epidemiologic studies for quantifying the health effects of low-dose ionizing radiation. In our judgment, no single population can be recommended for study on purely scientific grounds, since the largest group offers only a small chance to obtain a definitive result. On the other hand, if social pressures and regulatory agencies mandate that such studies be attempted, we would recommend prospective cohort studies of occupational populations. We propose that a national worker registry be developed using ionizing radiation as the prototype for studying other occupational exposures. The problems related to studying low-level radiation are not unique, but apply equally to investigations dealing with a great variety of toxic agents. A national plan for collecting information on workers' exposure and health could provide a cost-efficient means to answer public health questions posed by the Congress, scientists and the public. PMID:7294269

  18. Astronaut Exposures to Ionizing Radiation in a Lightly-Shielded Spacesuit

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Simonsen, L. C.; Shinn, J. L.; Kim, M.-H. Y.; Cucinotta, F. A.; Badavi, F. F.; Atwell, W.

    1999-01-01

    The normal working and living areas of the astronauts are designed to provide an acceptable level of protection against the hazards of ionizing radiation of the space environment. Still there are occasions when they must don a spacesuit designed mainly for environmental control and mobility and leave the confines of their better-protected domain. This is especially true for deep space exploration. The impact of spacesuit construction on the exposure of critical astronaut organs will be examined in the ionizing radiation environments of free space, the lunar surface and the Martian surface. The computerized anatomical male model is used to evaluate astronaut self-shielding factors and to determine space radiation exposures to critical radiosensitive human organs.

  19. Inhibition of gastric secretion in guinea pig by relatively low dose ionizing radiation

    SciTech Connect

    Batzri, S.; Catravas, G.

    1988-11-01

    We evaluated the effect of a single dose of ionizing radiation on gastric secretion in awake guinea pigs equipped with a permanent gastric cannula. Changes in gastric secretion were measured using a dye dilution technique. Infusion of histamine increased acid and fluid output and there was a positive correlation (r = 0.93) between the two. Total body irradiation with 400 cGy, like cimetidine, suppressed acid and fluid secretion under basal conditions and during histamine stimulation by 50-90%. Recovery from the radiation damage was only partial after one week. Irradiation inhibited the rise in gastric juice volume during histamine stimulation and also reduced the normal gain in body weight of the guinea pig. These results demonstrate that ionizing radiations have an immediate and long lasting effects on the gastric mucosal function of the guinea pig.

  20. Molecular investigation of the radiation resistance of edible cyanobacterium Arthrospira sp. PCC 8005

    PubMed Central

    Badri, Hanène; Monsieurs, Pieter; Coninx, Ilse; Wattiez, Ruddy; Leys, Natalie

    2015-01-01

    The aim of this work was to characterize in detail the response of Arthrospira to ionizing radiation, to better understand its radiation resistance capacity. Live cells of Arthrospira sp. PCC 8005 were irradiated with 60Co gamma rays. This study is the first, showing that Arthrospira is highly tolerant to gamma rays, and can survive at least 6400 Gy (dose rate of 527 Gy h−1), which identified Arthrospira sp. PCC 8005 as a radiation resistant bacterium. Biochemical, including proteomic and transcriptomic, analysis after irradiation with 3200 or 5000 Gy showed a decline in photosystem II quantum yield, reduced carbon fixation, and reduced pigment, lipid, and secondary metabolite synthesis. Transcription of photo-sensing and signaling pathways, and thiol-based antioxidant systems was induced. Transcriptomics did show significant activation of ssDNA repair systems and mobile genetic elements (MGEs) at the RNA level. Surprisingly, the cells did not induce the classical antioxidant or DNA repair systems, such superoxide dismutase (SOD) enzyme and the RecA protein. Arthrospira cells lack the catalase gene and the LexA repressor. Irradiated Arthrospira cells did induce strongly a group of conserved proteins, of which the function in radiation resistance remains to be elucidated, but which are a promising novel routes to be explored. This study revealed the radiation resistance of Arthrospira, and the molecular systems involved, paving the way for its further and better exploitation. PMID:25678338

  1. Multiphoton fragmentation and ionization of CF{sub 2}HCl molecules and clusters by UV radiation

    SciTech Connect

    Lokhman, V. N.; Ogurok, D. D.; Ryabov, E. A.

    2006-07-15

    The results of experimental studies of multiphoton ionization of CF{sub 2}HCl molecules and clusters by UV laser radiation in the wavelength range 217-236 nm are reported. In the case of molecules, the main reaction products are CF{sub 2}H{sup +} and CF{sup +} ions as well as atomic chlorine. It is found that the spectra of the products of ionization of free molecules and molecules condensed into clusters differ qualitatively: multiphoton ionization of clusters does not yield CF{sub 2}H{sup +} ions. The dependences of the ion yield on the intensity of laser radiation and its wavelength are measured. The effect of a constant electric field and the radiation spectral width on the multiphoton ionization process is demonstrated. The shape of the velocity distributions is determined for a number of products. A strong anisotropy is detected in the reaction of formation of CF{sub 2}H{sup +} ions. Possible mechanisms for these processes are discussed.

  2. Mass-Analyzed Threshold Ionization (MATI) Spectroscopy of Atoms and Molecules using VUV Synchrotron Radiation

    SciTech Connect

    Kostko, Oleg; Kim, Sang Kyu; Leone, Stephen R.; Ahmed, Musahid

    2009-01-28

    Mass-analyzed threshold ionization (MATI) spectroscopy using synchrotron radiation (Advanced Light Source, Lawrence Berkeley National Laboratory) has been performed for Ar, N2, O2, N2O, H2O, C2H2, and C6H6. MATI allows for a better determination of ionization energies compared to those derived from photoionization efficiency curves traditionally used in synchrotron photoionization mass spectrometry. The separation of the long-lived Rydberg state from the directly-formed prompt ion, essential for a meaningful MATI spectrum, has been accomplished by employing an arrangement of ion optics coupled to unique electric-field pulsing schemes. For Ar, a number of resolved bands below the ionization energy are observed, and these are ascribed to high-n,l Rydberg states prepared in the MATI scheme. The first vibrational stateresolved MATI spectra of N2 and O2 are reported and spectral characteristics are discussed in comparison with previously-reported threshold photoelectron spectroscopic studies. While MATI performed with synchrotron radiation is intrinsically less sensitive compared to laser based sources, this work demonstrates that MATI spectroscopy performed with widely tunable VUV radiation is a complementary technique for studying the ionization spectroscopy of polyatomic molecules.

  3. Morphological and transcriptional response of an anhydrobiotic insect to ionizing radiation and desiccation: steps forward in understanding molecular background of extreme radioresistance in higher eukaryotes

    NASA Astrophysics Data System (ADS)

    Gusev, Oleg; Novikova, Nataliya; Sychev, Vladimir; Okuda, Takashi; Kikawada, Takahiro; Sakashita, Tetsuya; Mukae, Kyosuke

    2012-07-01

    Life in extreme or drastically changing environments in many cases leads to evolutionary evolvement of mechanisms of cross-resistance to different abiotic stresses, often never actually faced by the organism in its natural habitat. Larvae of the sleeping chironomidPolypedilum vanderplanki (Diptera) are able to resist complete desiccation and in the dry form survive under excess of various abiotic stresses, including exposure to space environment. One of the most intriguing features of the anhydrobiotic larvae is resistance to extremely high doses of different types of ionizing radiation. To understand the cross-tolerance mechanism, we have analyzed the structural changes in the nuclear DNA using transmission electron microscopy and DNA comet assays in relation to anhydrobiosis and radiation. We find that dehydration causes alterations in chromatin structure and a severe fragmentation of nuclear DNA in the cells of the larvae despite successful anhydrobiosis. The DNA fragmentation level and the recovery of DNA integrity in the rehydrated after anhydrobiosis larvae were similar to those of hydrated larvae irradiated with 70 Gy of high-linear energy transfer (LET) ions (4He+). In comparison, low-LET radiation (gamma rays) of the same dose causes less initial damage to the larvae, and recovery of DNA repair is complete within 24 h. Genome-wide analysis of mRNA expression in the larvae revealed that a large group of genes (including antioxidants, anhydrobiosis-specific biomolecules and protein-reparation enzymes) showed a similar patterns of activity in response to both desiccation and ionizing radiation. We conclude that t one of the factors explaining the relationship between the resistance to ionizing radiation and the ability to undergo anhydrobiosis in the sleeping chironomid would be an adaptation to desiccation-inflicted proteins and nuclear DNA damage.

  4. Computer image analysis of etched tracks from ionizing radiation

    NASA Technical Reports Server (NTRS)

    Blanford, George E.

    1994-01-01

    I proposed to continue a cooperative research project with Dr. David S. McKay concerning image analysis of tracks. Last summer we showed that we could measure track densities using the Oxford Instruments eXL computer and software that is attached to an ISI scanning electron microscope (SEM) located in building 31 at JSC. To reduce the dependence on JSC equipment, we proposed to transfer the SEM images to UHCL for analysis. Last summer we developed techniques to use digitized scanning electron micrographs and computer image analysis programs to measure track densities in lunar soil grains. Tracks were formed by highly ionizing solar energetic particles and cosmic rays during near surface exposure on the Moon. The track densities are related to the exposure conditions (depth and time). Distributions of the number of grains as a function of their track densities can reveal the modality of soil maturation. As part of a consortium effort to better understand the maturation of lunar soil and its relation to its infrared reflectance properties, we worked on lunar samples 67701,205 and 61221,134. These samples were etched for a shorter time (6 hours) than last summer's sample and this difference has presented problems for establishing the correct analysis conditions. We used computer counting and measurement of area to obtain preliminary track densities and a track density distribution that we could interpret for sample 67701,205. This sample is a submature soil consisting of approximately 85 percent mature soil mixed with approximately 15 percent immature, but not pristine, soil.

  5. Apparatus and method for the simultaneous detection of neutrons and ionizing electromagnetic radiation

    DOEpatents

    Bell, Zane W.

    2000-01-01

    A sensor for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising: a sensor for the detection of gamma radiation, the sensor defining a sensing head; the sensor further defining an output end in communication with the sensing head; and an exterior neutron-sensitive material configured to form around the sensing head; wherein the neutron-sensitive material, subsequent to the capture of the neutron, fissions into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the first excited state decaying via the emission of a single gamma ray at 478 keV which can in turn be detected by the sensing head; and wherein the sensing head can also detect the ionizing electromagnetic radiation from an incident radiation field without significant interference from the neutron-sensitive material. A method for simultaneously detecting neutrons and ionizing electromagnetic radiation comprising the steps of: providing a gamma ray sensitive detector comprising a sensing head and an output end; conforming an exterior neutron-sensitive material configured to form around the sensing head of the detector; capturing neutrons by the sensing head causing the neutron-sensitive material to fission into an alpha-particle and a .sup.7 Li ion that is in a first excited state in a majority of the fissions, the state decaying via the emission of a single gamma ray at 478 keV; sensing gamma rays entering the detector through the neutron-sensitive material; and producing an output through a readout device coupled to the output end; wherein the detector provides an output which is proportional to the energy of the absorbed ionizing electromagnetic radiation.

  6. Interactive Learning Module Improves Resident Knowledge of Risks of Ionizing Radiation Exposure From Medical Imaging.

    PubMed

    Sheng, Alexander Y; Breaud, Alan H; Schneider, Jeffrey I; Kadom, Nadja; Mitchell, Patricia M; Linden, Judith A

    2016-01-01

    Physician awareness of the risks of ionizing radiation exposure related to medical imaging is poor. Effective educational interventions informing physicians of such risk, especially in emergency medicine (EM), are lacking. The SIEVERT (Suboptimal Ionizing Radiation Exposure Education - A Void in Emergency Medicine Residency Training) learning module was designed to improve provider knowledge of the risks of radiation exposure from medical imaging and comfort in communicating these risks to patients. The 1-hour module consists of introductory lecture, interactive discussion, and role-playing scenarios. In this pilot study, we assessed the educational effect using unmatched, anonymous preintervention and postintervention questionnaires that assessed fund of knowledge, participant self-reported imaging ordering practices in several clinical scenarios, and trainee comfort level in discussing radiation risks with patients. All 25 EM resident participants completed the preintervention questionnaire, and 22 completed the postintervention questionnaire within 4 hours after participation. Correct responses on the 14-question learning assessment increased from 6.32 (standard deviation = 2.36) preintervention to 12.23 (standard deviation = 1.85) post-intervention. Overall, 24% of residents were comfortable with discussing the risks of ionizing radiation exposure with patients preintervention, whereas 41% felt comfortable postintervention. Participants ordered fewer computed tomography scans in 2 of the 4 clinical scenarios after attending the educational intervention. There was improvement in EM residents' knowledge regarding the risks of ionizing radiation exposure from medical imaging, and increased participant self-reported comfort levels in the discussion of these risks with patients after the 1-hour SIEVERT learning module. PMID:26657346

  7. [Ionizing radiation in the aeronautics industry. Non-destructive testing].

    PubMed

    La Verde, R; Travaglini, C

    1983-08-25

    The constant increase in the non-military use of nuclear energy in various fields induced this study of one particular field: the aero industry. Alitalia has been using gammagraphy and industrial metallography for nondestructive testing for over 20 years. Workers exposed to ionising radiations at work are protected by precisely detailed standards based on extremely rigorous national and international legislation. The health and protection of these workers is entrusted to a Company Doctor and a Qualified Specialist. The latter is thought to be indispensable since he is responsible for primary preventions as well as prompt diagnosis. PMID:6866316

  8. THE ORIGIN AND OPTICAL DEPTH OF IONIZING RADIATION IN THE 'GREEN PEA' GALAXIES

    SciTech Connect

    Jaskot, A. E.; Oey, M. S.

    2013-04-01

    Although Lyman-continuum (LyC) radiation from star-forming galaxies likely drove the reionization of the universe, observations of star-forming galaxies at low redshift generally indicate low LyC escape fractions. However, the extreme [O III]/[O II] ratios of the z = 0.1-0.3 Green Pea galaxies may be due to high escape fractions of ionizing radiation. To analyze the LyC optical depths and ionizing sources of these rare, compact starbursts, we compare nebular photoionization and stellar population models with observed emission lines in the Peas' Sloan Digital Sky Survey (SDSS) spectra. We focus on the six most extreme Green Peas, the galaxies with the highest [O III]/[O II] ratios and the best candidates for escaping ionizing radiation. The Balmer line equivalent widths and He I {lambda}3819 emission in the extreme Peas support young ages of 3-5 Myr, and He II {lambda}4686 emission in five extreme Peas signals the presence of hard ionizing sources. Ionization by active galactic nuclei or high-mass X-ray binaries is inconsistent with the Peas' line ratios and ages. Although stacked spectra reveal no Wolf-Rayet (WR) features, we tentatively detect WR features in the SDSS spectra of three extreme Peas. Based on the Peas' ages and line ratios, we find that WR stars, chemically homogeneous O stars, or shocks could produce the observed He II emission. If hot stars are responsible, then the Peas' optical depths are ambiguous. However, accounting for emission from shocks lowers the inferred optical depth and suggests that the Peas may be optically thin. The Peas' ages likely optimize the escape of LyC radiation; they are old enough for supernovae and stellar winds to reshape the interstellar medium, but young enough to possess large numbers of UV-luminous O or WR stars.

  9. Prenatal exposure to ionizing radiation and subsequent development of seizures

    SciTech Connect

    Dunn, K.; Yoshimaru, H.; Otake, M.; Annegers, J.F.; Schull, W.J. )

    1990-01-01

    Seizures are a frequent sequela of impaired brain development and can be expected to affect more children with radiation-related brain damage than children without such damage. This report deals with the incidence and type of seizures among survivors prenatally exposed to the atomic bombing of Hiroshima and Nagasaki, and their association with specific stages of prenatal development at the time of irradiation. Fetal radiation dose was assumed to be equal to the dose to the maternal uterus. Seizures here include all references in the clinical record to seizure, epilepsy, or convulsion. Histories of seizures were obtained at biennial routine clinical examinations starting at about the age of 2 years. These clinical records were used to classify seizures as febrile or unprovoked (without precipitating cause). No seizures were ascertained among subjects exposed 0-7 weeks after fertilization at doses higher than 0.10 Gy. The incidence of seizures was highest with irradiation at the eighth through the 15th week after fertilization among subjects with doses exceeding 0.10 Gy and was linearly related to the level of fetal exposure. This obtains for all seizures without regard to the presence of fever or precipitating causes, and for unprovoked seizures. When the 22 cases of severe mental retardation were excluded, the increase in seizures was only suggestively significant and only for unprovoked seizures. After exposure at later stages of development, there was no increase in recorded seizures.

  10. Prenatal exposure to ionizing radiation and subsequent development of seizures.

    PubMed

    Dunn, K; Yoshimaru, H; Otake, M; Annegers, J F; Schull, W J

    1990-01-01

    Seizures are a frequent sequela of impaired brain development and can be expected to affect more children with radiation-related brain damage than children without such damage. This report deals with the incidence and type of seizures among survivors prenatally exposed to the atomic bombing of Hiroshima and Nagasaki, and their association with specific stages of prenatal development at the time of irradiation. Fetal radiation dose was assumed to be equal to the dose to the maternal uterus. Seizures here include all references in the clinical record to "seizure," "epilepsy," or "convulsion." Histories of seizures were obtained at biennial routine clinical examinations starting at about the age of 2 years. These clinical records were used to classify seizures as febrile or unprovoked (without precipitating cause). No seizures were ascertained among subjects exposed 0-7 weeks after fertilization at doses higher than 0.10 Gy. The incidence of seizures was highest with irradiation at the eighth through the 15th week after fertilization among subjects with doses exceeding 0.10 Gy and was linearly related to the level of fetal exposure. This obtains for all seizures without regard to the presence of fever or precipitating causes, and for unprovoked seizures. When the 22 cases of severe mental retardation were excluded, the increase in seizures was only suggestively significant and only for unprovoked seizures. After exposure at later stages of development, there was no increase in recorded seizures. PMID:2293744

  11. Pluripotent Stem Cells and DNA Damage Response to Ionizing Radiations.

    PubMed

    Mujoo, Kalpana; Butler, E Brian; Pandita, Raj K; Hunt, Clayton R; Pandita, Tej K

    2016-07-01

    Pluripotent stem cells (PSCs) hold great promise in regenerative medicine, disease modeling, functional genomics, toxicological studies and cell-based therapeutics due to their unique characteristics of self-renewal and pluripotency. Novel methods for generation of pluripotent stem cells and their differentiation to the specialized cell types such as neuronal cells, myocardial cells, hepatocytes and beta cells of the pancreas and many other cells of the body are constantly being refined. Pluripotent stem cell derived differentiated cells, including neuronal cells or cardiac cells, are ideal for stem cell transplantation as autologous or allogeneic cells from healthy donors due to their minimal risk of rejection. Radiation-induced DNA damage, ultraviolet light, genotoxic stress and other intrinsic and extrinsic factors triggers a series of biochemical reactions known as DNA damage response. To maintain genomic stability and avoid transmission of mutations into progenitors cells, stem cells have robust DNA damage response signaling, a contrast to somatic cells. Stem cell transplantation may protect against radiation-induced late effects. In particular, this review focuses on differential DNA damage response between stem cells and derived differentiated cells and the possible pathways that determine such differences. PMID:27332952

  12. Quantitative Phosphoproteomics Identifies Filaggrin and other Targets of Ionizing Radiation in a Human Skin Model

    SciTech Connect

    Yang, Feng; Waters, Katrina M.; Webb-Robertson, Bobbie-Jo M.; Sowa, Marianne B.; Freiin von Neubeck, Claere H.; Aldrich, Joshua T.; Markillie, Lye Meng; Wirgau, Rachel M.; Gristenko, Marina A.; Zhao, Rui; Camp, David G.; Smith, Richard D.; Stenoien, David L.

    2012-04-17

    Our objective here was to perform a quantitative phosphoproteomic study on a reconstituted human skin tissue to identify low and high dose ionizing radiation dependent signaling in a complex 3-dimensional setting. Application of an isobaric labeling strategy using sham and 3 radiation doses (3, 10, 200 cGy) resulted in the identification of 1113 unique phosphopeptides. Statistical analyses identified 151 phosphopeptides showing significant changes in response to radiation and radiation dose. Proteins responsible for maintaining skin structural integrity including keratins and desmosomal proteins (desmoglein, desmoplakin, plakophilin 1 and 2,) had altered phosphorylation levels following exposure to both low and high doses of radiation. A phosphorylation site present in multiple copies in the linker regions of human profilaggrin underwent the largest fold change. Increased phosphorylation of these sites coincided with altered profilaggrin processing suggesting a role for linker phosphorylation in human profilaggrin regulation. These studies demonstrate that the reconstituted human skin system undergoes a coordinated response to ionizing radiation involving multiple layers of the stratified epithelium that serve to maintain skin barrier functions and minimize the damaging consequences of radiation exposure.

  13. A Molecular Profile of the Endothelial Cell Response to Ionizing Radiation.

    PubMed

    Himburg, Heather A; Sasine, Joshua; Yan, Xiao; Kan, Jenny; Dressman, Holly; Chute, John P

    2016-08-01

    Ionizing radiation exposure can cause acute radiation sickness (ARS) by damaging the hematopoietic compartment. Radiation damages quiescent hematopoietic stem cells (HSCs) and proliferating hematopoietic cells, resulting in neutropenia, thrombocytopenia and increased risk for long-term hematopoietic dysfunction and myelodysplasia. While some aspects of the hematopoietic response to radiation injury are intrinsic to hematopoietic cells, the recovery of the HSC pool and overall hematopoiesis is also dependent on signals from bone marrow endothelial cells (BM ECs) within the HSC vascular niche. The precise mechanisms through which BM ECs regulate HSC regeneration remain unclear. Characterization of the altered EC gene expression that occurs in response to radiation could provide a roadmap to the discovery of EC-derived mechanisms that regulate hematopoietic regeneration. Here, we show that 5 Gy total-body irradiation substantially alters the expression of numerous genes in BM ECs within 24 h and this molecular response largely resolves by day 14 postirradiation. Several unique and nonannotated genes, which encode secreted proteins were upregulated and downregulated in ECs in response to radiation. These results highlight the complexity of the molecular response of BM ECs to ionizing radiation and identify several candidate mechanisms that should be prioritized for functional analysis in models of hematopoietic injury and regeneration. PMID:27387861

  14. Biodosimetry of ionizing radiation by selective painting of prematurely condensed chromosomes in human lymphocytes

    NASA Technical Reports Server (NTRS)

    Durante, M.; George, K.; Yang, T. C.

    1997-01-01

    Painting of interphase chromosomes can be useful for biodosimetric purposes in particular cases such as radiation therapy, accidental exposure to very high radiation doses and exposure to densely ionizing radiation, for example during space missions. Biodosimetry of charged-particle radiation is analyzed in the present paper. Target cells were human peripheral blood lymphocytes irradiated in vitro with gamma rays, protons and iron ions. After exposure, lymphocytes were incubated for different times to allow repair of radiation-induced damage and then fused to mitotic hamster cells to promote premature condensation in the interphase chromosomes. Chromosome spreads were then hybridized with whole-chromosome DNA probes labeled with fluorescent stains. Dose-response curves for the induction of chromatin fragments shortly after exposure, as well as the kinetics of rejoining and misrejoining, were not markedly dependent on linear energy transfer. However, after exposure to heavy ions, more aberrations were scored in the interphase cells after incubation for repair than in metaphase samples harvested at the first postirradiation mitosis. On the other hand, no significant differences were observed in the two samples after exposure to sparsely ionizing radiation. These results suggest that interphase chromosome painting can be a useful tool for biodosimetry of particle radiation.

  15. Selected morphological changes in Artemia franciscana after ionizing radiation exposure.

    PubMed

    Dvořák, P; Zd'árský, M; Beňová, K; Spalek, M

    2012-08-01

    Nauplii of Artemia franciscana were irradiated by the doses of 0.25, 0.5, 1.0, and 2.5 kGy (60)Co. Dimensions of the body length, body width, intestine width, intestine epithelium width, and intestine lumen width, as well as the mutual ratios of dimensions were determined in 126 specimens. Ratios of the body length/body width (3.98, 3.60, 3.59, and 3.45 vs. 4.13 of control group), and ratios of the intestine epithelium width/intestine lumen width (0.64, 0.52, 0.51, and 0.45 vs. 0.85 of control group), according to the doses, were the most important parameters of evaluation of dependence of morphological changes on radiation doses. PMID:22673764

  16. Increase of Ionizing Radiation at the Pfotzer Maximum

    NASA Astrophysics Data System (ADS)

    Gomez, Enrique; Carmichael-Coker, Michele

    2015-04-01

    Verso l'alto is a multi-disciplinary research and development project whose goal is to gain insight into the cosmic ray profile of the atmosphere and geolocation of terrestrial gamma-ray flashes (TGFs) over North Carolina, USA. This experiment is comprised of high-altitude weather balloons carrying radiation, pressure and temperature detectors. Eight successful balloon flights have been completed from October 2012-June 2014. Live tracking and telemetry of the flight is performed by an amateur radio communications payload, and beacon coordinates are uploaded to aprs.fi for real-time access online. We conclude that fluctuation peaks within the tropopause are due to the Pfotzer Maximum. Other statistically significant peaks within the time scale of minutes are observed. All data sets confirm peak counts within the Pfotzer Maximum, ranging from altitudes 13.4-22 km (44,146-72,441 feet).

  17. Ionizing Radiation Dose Due to the Use of Agricultural Fertilizers

    SciTech Connect

    Umisedo, Nancy K.; Okuno, Emico; Medina, Nilberto H.; Colacioppo, Sergio; Hiodo, Francisco Y.

    2008-08-07

    The transference of radionuclides from the fertilizers to/and from soils to the foodstuffs can represent an increment in the internal dose when the vegetables are consumed by the human beings. This work evaluates the contribution of fertilizers to the increase of radiation level in the environment and of dose to the people. Samples of fertilizers, soils and vegetables produced in farms located in the neighbourhood of Sao Paulo city in the State of Sao Paulo, Brazil were analysed through gamma spectroscopy. The values of specific activity of {sup 40}K, {sup 238}U and {sup 232}Th show that there is no significant transference of natural radionuclides from fertilizers to the final product of the food chain. The annual committed effective dose due to the ingestion of {sup 40}K contained in the group of consumed vegetables analysed in this work resulted in the very low value of 0.882 {mu}Sv.

  18. Bikini Atoll ionizing radiation survey, May 1985-May 1986

    SciTech Connect

    Shingleton, K.L.; Cate, J.L.; Trent, M.G.; Robison, W.L.

    1987-10-01

    Between 1946 and 1958, the United States conducted 23 nuclear tests at the Bikini Atoll in the Marshall Islands, which resulted in extensive radioactive contamination of a number of islands in the atoll and prevented the timely resettlement of the native population. Although the external dose rates from beta and gamma radiation have been previously determined by aerial survey and a variety of ground measurement techniques, technical constraints limited the assessment of external beta dose rates that result from the /sup 137/Cs and /sup 90/Sr//sup 90/Y contamination on the islands. Now, because of the recent development of very thin thermoluminescent dosimeters (TLDs), the external beta dose rates can be measured. 18 refs., 7 figs., 5 tabs.

  19. Radiation sensitivity of Salmonella isolates relative to resistance to ampicillin, chloramphenicol or gentamicin

    NASA Astrophysics Data System (ADS)

    Niemira, Brendan A.; Lonczynski, Kelly A.; Sommers, Christopher H.

    2006-09-01

    Antibiotic resistance of inoculated bacteria is a commonly used selective marker. Bacteria resistant to the antibiotic nalidixic acid have been shown to have an increased sensitivity to irradiation. The purpose of this research was to screen a collection of Salmonella isolates for antibiotic resistance and determine the association, if any, of antibiotic resistance with radiation sensitivity. Twenty-four clinical isolates of Salmonella were screened for native resistance to multiple concentrations of ampicillin (Amp), chloramphenicol (Chl), or gentamicin (Gm). Test concentrations were chosen based on established clinical minimum inhibitory concentration (MIC) levels, and isolates were classified as either sensitive or resistant based on their ability to grow at or above the MIC. Salmonella cultures were grown overnight at (37 °C) in antibiotic-amended tryptic soy broth (TSB). Native resistance to Gm was observed with each of the 24 isolates (100%). Eight isolates (33%) were shown to be resistant to Amp, while seven isolates (29%) were shown to be resistant to Chl. In separate experiments, Salmonella cultures were grown overnight (37 °C) in TSB, centrifuged, and the cell pellets were re-suspended in phosphate buffer. The samples were then gamma irradiated at doses up to 1.0 kGy. The D10 values (the ionizing radiation dose required to reduce the viable number of microorganisms by 90%) were determined for the 24 isolates and they ranged from 0.181 to 0.359 kGy. No correlation was found between the D10 value of the isolate and its sensitivity or resistance to each of the three antibiotics. Resistance to Amp or Chl is suggested as appropriate resistance marker for Salmonella test strains to be used in studies of irradiation.

  20. Synthesis and radiation resistance of fullerenes and fullerene derivatives

    NASA Astrophysics Data System (ADS)

    Shilin, V. A.; Lebedev, V. T.; Sedov, V. P.; Szhogina, A. A.

    2016-07-01

    The parameters of an electric-arc facility for the synthesis of fullerenes and endohedral metallofullerenes are optimized. The resistance of C60 and C70 fullerenes and C60(OH)30 and C70(OH)30 fullerenols against neutron irradiation is studied. It is established that the radiation resistance of the fullerenes is higher than that of the fullerenols, but the radiation resistance of the Gd@C2 n endometallofullerenes is lower than that of the corresponding Gd@C2 n (OH)38 fullerenols. The radiation resistance of mixtures of Me@C2 n (OH)38 ( Me = Gd, Tb, Sc, Fe, and Pr) endometallofullerenes with C60(OH)30 is determined. The factors affecting the radiation resistance of the fullerenes and fullerenols are discussed.

  1. Free Radicals Generated by Ionizing Radiation Signal Nuclear Translocation of p53

    NASA Technical Reports Server (NTRS)

    Martinez, J. D.; Pennington, M. E.; Craven, M. T.; Warters, R. L.

    1997-01-01

    The p53 tumor suppressor is a transcription factor that regulates several pathways, which function collectively to maintain the integrity of the genome. Nuclear localization is critical for wild-type function. However, the signals that regulate subcellular localization of p53 have not been identified. Here, we examine the effect of ionizing radiation on the subcellular localization of p53 in two cell lines in which p63 is normally sequestered in the cytoplasm and found that ionizing radiation caused a biphasic translocation response. p53 entered the nucleus 1-2 hours postirradiation (early response), subsequently emerged from the nucleus, and then again entered the nucleus 12-24 hours after the cells had been irradiated (delayed response). These changes in subcellular localization could be completely blocked by the free radical scavenger, WR1065. By comparison, two DNA-damaging agents that do not generate free radicals, mitomycin C and doxorubicin, caused translocation only after 12-24 h of exposure to the drugs, and this effect could not be inhibited by WR1065. Hence, although all three DNA-damaging agents induced relocalization of p53 to the nucleus, only the translocation caused by radiation was sensitive to free radical scavenging. We suggest that the free radicals generated by ionizing radiation can signal p53 translocation to the nucleus.

  2. Ground-Level Ozone Following Astrophysical Ionizing Radiation Events: An Additional Biological Hazard?

    PubMed

    Thomas, Brian C; Goracke, Byron D

    2016-01-01

    Astrophysical ionizing radiation events such as supernovae, gamma-ray bursts, and solar proton events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in solar UV radiation at Earth's surface and in the upper levels of the ocean. Other work has also considered the potential impact of nitric acid rainout, concluding that no significant threat is likely. Not yet studied to date is the potential impact of ozone produced in the lower atmosphere following an ionizing radiation event. Ozone is a known irritant to organisms on land and in water and therefore may be a significant additional hazard. Using previously completed atmospheric chemistry modeling, we examined the amount of ozone produced in the lower atmosphere for the case of a gamma-ray burst and found that the values are too small to pose a significant additional threat to the biosphere. These results may be extended to other ionizing radiation events, including supernovae and extreme solar proton events. PMID:26745353

  3. Evaluation of non-radiologist physicians' knowledge on aspects related to ionizing radiation in imaging*

    PubMed Central

    Madrigano, Renata Rodrigues; Abrão, Karen Cristine; Puchnick, Andrea; Regacini, Rodrigo

    2014-01-01

    Objective To assess the non-radiologist physicians' knowledge on the use of ionizing radiation in imaging. Materials and Methods Cross-sectional study utilizing an anonymous questionnaire responded by physicians in clinical and surgical specialties, divided into two parts as follows: one including questions about the physicians' characteristics, frequency of imaging studies requests and participation in professional updating events, and another part including multiple choice questions approaching general knowledge about radiation, optimization principles and radioprotection. Results From a total of 309 questionnaires, 120 (38.8%) were responded, 50% by physicians in surgical specialties and 50% in clinical specialties; respectively 45% and 2.5% of physicians responded that magnetic resonance imaging and ultrasonography use ionizing radiation. Overall, the average grade was higher for surgical specialists with no significant difference, except for the question about exposure in pregnant women (p = 0.047). Physicians who are professionally updated, particularly those attending clinical meetings (p = 0.050) and participating in teaching activities (p = 0.047), showed statistically superior knowledge about ionizing radiation as compared with others. Conclusion The non-radiologist physicians' knowledge is heterogeneous and in some points needs to be improved. Multidisciplinary clinical meetings and teaching activities are important ways to disseminate information on the subject. PMID:25741087

  4. Ionizing radiation test results for an automotive microcontroller on board the Schiaparelli Mars lander

    NASA Astrophysics Data System (ADS)

    Tapani Nikkanen, Timo; Hieta, Maria; Schmidt, Walter; Genzer, Maria; Haukka, Harri; Harri, Ari-Matti

    2016-04-01

    The Finnish Meteorological Institute (FMI) has delivered a pressure and a humidity instrument for the ESA ExoMars 2016 Schiaparelli lander mission. Schiaparelli is scheduled to launch towards Mars with the Trace Gas Orbiter on 14th of March 2016. The DREAMS-P (pressure) and DREAMS-H (Humidity) instruments are operated utilizing a novel FMI instrument controller design based on a commercial automotive microcontroller (MCU). A custom qualification program was implemented to qualify the MCU for the relevant launch, cruise and surface operations environment of a Mars lander. Resilience to ionizing radiation is one of the most critical requirements for a digital component operated in space or at planetary bodies. Thus, the expected Total Ionizing Dose accumulated by the MCU was determined and a sample of these components was exposed to a Co-60 gamma radiation source. Part of the samples was powered during the radiation exposure to include the effect of electrical biasing. All of the samples were verified to withstand the expected total ionizing dose with margin. The irradiated test samples were then radiated until failure to determine their ultimate TID.

  5. Ionizing Radiation Activates AMP-Activated Kinase (AMPK): A Target for Radiosensitization of Human Cancer Cells

    SciTech Connect

    Sanli, Toran; Rashid, Ayesha; Liu Caiqiong

    2010-09-01

    Purpose: Adenosine monophosphate (AMP)-activated kinase (AMPK) is a molecular energy sensor regulated by the tumor suppressor LKB1. Starvation and growth factors activate AMPK through the DNA damage sensor ataxia-telangiectasia mutated (ATM). We explored the regulation of AMPK by ionizing radiation (IR) and its role as a target for radiosensitization of human cancer cells. Methods and Materials: Lung, prostate, and breast cancer cells were treated with IR (2-8 Gy) after incubation with either ATM or AMPK inhibitors or the AMPK activator metformin. Then, cells were subjected to either lysis and immunoblotting, immunofluorescence microscopy, clonogenic survival assays, or cell cycle analysis. Results: IR induced a robust phosphorylation and activation of AMPK in all tumor cells, independent of LKB1. IR activated AMPK first in the nucleus, and this extended later into cytoplasm. The ATM inhibitor KU-55933 blocked IR activation of AMPK. AMPK inhibition with Compound C or anti-AMPK {alpha} subunit small interfering RNA (siRNA) blocked IR induction of the cell cycle regulators p53 and p21{sup waf/cip} as well as the IR-induced G2/M arrest. Compound C caused resistance to IR, increasing the surviving fraction after 2 Gy, but the anti-diabetic drug metformin enhanced IR activation of AMPK and lowered the surviving fraction after 2 Gy further. Conclusions: We provide evidence that IR activates AMPK in human cancer cells in an LKB1-independent manner, leading to induction of p21{sup waf/cip} and regulation of the cell cycle and survival. AMPK appears to (1) participate in an ATM-AMPK-p21{sup waf/cip} pathway, (2) be involved in regulation of the IR-induced G2/M checkpoint, and (3) may be targeted by metformin to enhance IR responses.

  6. Ionizing radiation-induced metabolic oxidative stress and prolonged cell injury

    PubMed Central

    Azzam, Edouard I.; Jay-Gerin, Jean-Paul; Pain, Debkumar

    2013-01-01

    Cellular exposure to ionizing radiation leads to oxidizing events that alter atomic structure through direct interactions of radiation with target macromolecules or via products of water radiolysis. Further, the oxidative damage may spread from the targeted to neighboring, non-targeted bystander cells through redox-modulated intercellular communication mechanisms. To cope with the induced stress and the changes in the redox environment, organisms elicit transient responses at the molecular, cellular and tissue levels to counteract toxic effects of radiation. Metabolic pathways are induced during and shortly after the exposure. Depending on radiation dose, dose-rate and quality, these protective mechanisms may or may not be sufficient to cope with the stress. When the harmful effects exceed those of homeostatic biochemical processes, induced biological changes persist and may be propagated to progeny cells. Physiological levels of reactive oxygen and nitrogen species play critical roles in many cellular functions. In irradiated cells, levels of these reactive species may be increased due to perturbations in oxidative metabolism and chronic inflammatory responses, thereby contributing to the long-term effects of exposure to ionizing radiation on genomic stability. Here, in addition to immediate biological effects of water radiolysis on DNA damage, we also discuss the role of mitochondria in the delayed outcomes of ionization radiation. Defects in mitochondrial functions lead to accelerated aging and numerous pathological conditions. Different types of radiation vary in their linear energy transfer (LET) properties, and we discuss their effects on various aspects of mitochondrial physiology. These include short and long-term in vitro and in vivo effects on mitochondrial DNA, mitochondrial protein import and metabolic and antioxidant enzymes. PMID:22182453

  7. Repeated Nrf2 stimulation using sulforaphane protects fibroblasts from ionizing radiation

    SciTech Connect

    Mathew, Sherin T.; Bergström, Petra; Hammarsten, Ola

    2014-05-01

    Most of the cytotoxicity induced by ionizing radiation is mediated by radical-induced DNA double-strand breaks. Cellular protection from free radicals can be stimulated several fold by sulforaphane-mediated activation of the transcription factor Nrf2 that regulates more than 50 genes involved in the detoxification of reactive substances and radicals. Here, we report that repeated sulforaphane treatment increases radioresistance in primary human skin fibroblasts. Cells were either treated with sulforaphane for four hours once or with four-hour treatments repeatedly for three consecutive days prior to radiation exposure. Fibroblasts exposed to repeated-sulforaphane treatment showed a more pronounced dose-dependent induction of Nrf2-regulated mRNA and reduced amount of radiation-induced free radicals compared with cells treated once with sulforaphane. In addition, radiation- induced DNA double-strand breaks measured by gamma-H2AX foci were attenuated following repeated sulforaphane treatment. As a result, cellular protection from ionizing radiation measured by the 5-ethynyl-2′-deoxyuridine (EdU) assay was increased, specifically in cells exposed to repeated sulforaphane treatment. Sulforaphane treatment was unable to protect Nrf2 knockout mouse embryonic fibroblasts, indicating that the sulforaphane-induced radioprotection was Nrf2-dependent. Moreover, radioprotection by repeated sulforaphane treatment was dose-dependent with an optimal effect at 10 uM, whereas both lower and higher concentrations resulted in lower levels of radioprotection. Our data indicate that the Nrf2 system can be trained to provide further protection from radical damage. - Highlights: • Repeated treatment with sulforaphane protects fibroblasts from ionizing radiation • Repeated sulforaphane treatment attenuates radiation induced ROS and DNA damage • Sulforaphane mediated protection is Nrf2 dependent.

  8. Response of a forest ecotone to ionizing radiation. Final report

    SciTech Connect

    Murphy, P.G.; Sharitz, R.R.

    1986-05-01

    Compositional and structural characteristics of three forest types, including aspen dominated, maple-birch dominated, and an intervening ecotone (midecotone), were studied before and after irradiation in northern Wisconsin. The cumulative exposure resulting from 3300 hours of point-source gamma irradiation was estimated to be 55 kR at 10 m. In all three areas, the density of seedlings at 10 m was greatly reduced within a year following the 1972 radiation event. In the maple-birch area, seedlings were virtually absent at 10 m until 1982 and 1983 when their numbers were comparable to preirradiation levels, and 1984 when they were more than twice as abundant. In the aspen and midecotone areas, 1984 seedling densities at 10 m were only 42 and 17%, respectively, of the preirradiation levels. Similar but less pronounced seedling trends were observed at 20 m but not beyond that distance. Woody plants of tree stature were eliminated at 10 m in all three areas within two years of irradiation but by 1979 (maple-birch area) and 1982 (midecotone area) this size class was once again represented. By 1984 only the aspen area lacked plants at least 2.5 cm in dbh. In 1984, 12 years subsequent to irradiation, total leaf litter production was 109 and 97% of 1971 preirradiation levels at 10 m in aspen and midecotone areas, respectively. But at 10 m in the maple-birch area, it was only 58% of the preirradiation level.

  9. Radiation injury and acute death in Armadillidium vulgare (terrestrial isopod, Crustacea) subjected to ionizing radiation. [/sup 137/Cs

    SciTech Connect

    Nakatsuchi, Y.; Egami, N.

    1981-01-01

    From whole- and partial-body irradiation experiments with adult Armadillidium vulgare, the following conclusions were drawn: the LD/sub 50/-30 days for this animal when subjected to ..gamma.. radiation at 25 +- 2/sup 0/C was about 30 kR. Radiosensitivity of the animal changed during the molt cycle. Ionizing radiation increased mortality at ecdysis and during intermolt stages. Anatomical and histological observations indicated that (1) gastrointestinal injury as the major cause of acute death does not apply to this animal because the intestine is not a cell-proliferative organ: (2) the epidermis may be the critical target organ.

  10. Effect of the ionizing radiation on the rain-time atmospheric electric field

    NASA Astrophysics Data System (ADS)

    Yamauchi, Masatoshi; Takeda, Masahiko; Makino, Masahiko; Owada, Takeshi

    2013-04-01

    The atmospheric electric field, or potential gradient (PG) at Kakioka, 150 southwest of the Fukushima Nuclear Power Plant (NPP) shows peculiar behaviors after the accident, March 2012 due to the conductivity enhancement in the air by the ionizing radiation. This means that the PG provides significant information on the dynamics of the radioactive materials. During last EGU assembly 2012, we showed that the fine-weather PG decreased by one-two orders of magnitudes at the arrival of the radioactive plume, and that the PG recovered in various way depending on various types of re-suspension processes in addition to the physical decay of the deposited radioactive materials. We extended this work to the rain-time PG, which is very simple because of high variability of the PG depending on the cloud types and distribution. We yet found a statistical difference between rain-time PGs before and after the Fukushima NPP Accident: one-hour averaged rain-time PG during the first 45 days after the accident is not as much scattered to the negative side as those during the same period of different years or during 40 days before accident. Further examination of one-minute averaged data (1 Hz sampling) during the second half March for 2006-2012 revealed that this difference comes from short time-spans of negative peaks rather than the peak value after the accident compared to those before the accident. On the other hand, characteristics of positive peaks (cloud without rain) are unchanged. The results suggest either (1) the effect on the local charges in the rain cloud is narrowed under high dose of ionized radiation, making positive charges in the cloud less shielded by the negative charges, or (2) negative charge of ionized aerosol decays much faster under higher dose of ionized radiation due to the shortened time constant of the ionized aerosol (? 1-?, where ? is the atmospheric electric conductivity).

  11. Geometry and mass model of ionizing radiation experiments on the LDEF satellite

    NASA Technical Reports Server (NTRS)

    Colborn, B. L.; Armstrong, T. W.

    1992-01-01

    Extensive measurements related to ionizing radiation environments and effects were made on the LDEF satellite during its mission lifetime of almost 6 years. These data, together with the opportunity they provide for evaluating predictive models and analysis methods, should allow more accurate assessments of the space radiation environment and related effects for future missions in low Earth orbit. The LDEF radiation dosimetry data is influenced to varying degrees by material shielding effects due to the dosimeter itself, nearby components and experiments, and the spacecraft structure. A geometry and mass model is generated of LDEF, incorporating sufficient detail that it can be applied in determining the influence of material shielding on ionizing radiation measurements and predictions. This model can be used as an aid in data interpretation by unfolding shielding effects from the LDEF radiation dosimeter responses. Use of the LDEF geometry/mass model, in conjunction with predictions and comparisons with LDEF dosimetry data currently underway, will also allow more definitive evaluations of current radiation models for future mission applications.

  12. Characterization of a novel epigenetic effect of ionizing radiation: the death-inducing effect

    NASA Technical Reports Server (NTRS)

    Nagar, Shruti; Smith, Leslie E.; Morgan, William F.

    2003-01-01

    The detrimental effects associated with exposure to ionizing radiation have long been thought to result from the direct targeting of the nucleus leading to DNA damage; however, the emergence of concepts such as radiation-induced genomic instability and bystander effects have challenged this dogma. After cellular exposure to ionizing radiation, we have isolated a number of clones of Chinese hamster-human hybrid GM10115 cells that demonstrate genomic instability as measured by chromosomal destabilization. These clones show dynamic and persistent generation of chromosomal rearrangements multiple generations after the original insult. We hypothesize that these unstable clones maintain this delayed instability phenotype by secreting factors into the culture medium. To test this hypothesis we transferred filtered medium from unstable cells to unirradiated GM10115 cells. No GM10115 cells were able to survive this medium. This phenomenon by which GM10115 cells die when cultured in medium from chromosomally unstable GM10115 clones is the death-inducing effect. Medium transfer experiments indicate that a factor or factors is/are secreted by unstable cells within 8 h of growth in fresh medium and result in cell killing within 24 h. These factors are stable at ambient temperature but do not survive heating or freezing, and are biologically active when diluted with fresh medium. We present the initial description and characterization of the death-inducing effect. This novel epigenetic effect of radiation has implications for radiation risk assessment and for health risks associated with radiation exposure.

  13. Geometry and mass model of ionizing radiation experiments on the LDEF satellite. Final Report

    SciTech Connect

    Colborn, B.L.; Armstrong, T.W.

    1992-04-01

    Extensive measurements related to ionizing radiation environments and effects were made on the LDEF satellite during its mission lifetime of almost 6 years. These data, together with the opportunity they provide for evaluating predictive models and analysis methods, should allow more accurate assessments of the space radiation environment and related effects for future missions in low Earth orbit. The LDEF radiation dosimetry data is influenced to varying degrees by material shielding effects due to the dosimeter itself, nearby components and experiments, and the spacecraft structure. A geometry and mass model is generated of LDEF, incorporating sufficient detail that it can be applied in determining the influence of material shielding on ionizing radiation measurements and predictions. This model can be used as an aid in data interpretation by unfolding shielding effects from the LDEF radiation dosimeter responses. Use of the LDEF geometry/mass model, in conjunction with predictions and comparisons with LDEF dosimetry data currently underway, will also allow more definitive evaluations of current radiation models for future mission applications.

  14. Towards a unifying theory of late stochastic effects of ionizing radiation.

    PubMed

    Baverstock, Keith; Karotki, Andrei V

    2011-01-10

    The traditionally accepted biological basis for the late stochastic effects of ionizing radiation (cancer and hereditary disease), i.e. target theory, has so far been unable to accommodate the more recent findings of non-cancer disease and the so-called non-targeted effects, genomic instability and bystander effect, thus creating uncertainty in radiation risk estimation. We propose that ionizing radiation can give rise to these effects through two distinct and independent routes, one essentially genetic, termed here type A, and the other essentially epigenetic, termed type B. Type B processes entail envisaging phenotype as represented by a dynamic attractor and radiation acting as an agent that stresses cellular processes leading to the adoption of a variant attractor/phenotype. Evidence from the literature indicates that type B processes can lead to the inheritance of variant cell attractors and mediate a category of trans-generational effects quite distinct from classical Mendelian inherited disease, which is type A. The causal relationships for radiation-induced somatic human health detriment, i.e., cancer and non-cancer (e.g., cardiovascular) disease, are discussed from the point of view of the proposed classification. This approach unifies at a fundamental level the heritable and late somatic effects of radiation into a single causal framework that has the potential to be extended to the effects of the other environmental agents damaging to health. PMID:21078408

  15. Embryos of the zebrafish Danio rerio in studies of non-targeted effects of ionizing radiation.

    PubMed

    Choi, V W Y; Yu, K N

    2015-01-01

    The use of embryos of the zebrafish Danio rerio as an in vivo tumor model for studying non-targeted effects of ionizing radiation was reviewed. The zebrafish embryo is an animal model, which enables convenient studies on non-targeted effects of both high-linear-energy-transfer (LET) and low-LET radiation by making use of both broad-beam and microbeam radiation. Zebrafish is also a convenient embryo model for studying radiobiological effects of ionizing radiation on tumors. The embryonic origin of tumors has been gaining ground in the past decades, and efforts to fight cancer from the perspective of developmental biology are underway. Evidence for the involvement of radiation-induced genomic instability (RIGI) and the radiation-induced bystander effect (RIBE) in zebrafish embryos were subsequently given. The results of RIGI were obtained for the irradiation of all two-cell stage cells, as well as 1.5 hpf zebrafish embryos by microbeam protons and broad-beam alpha particles, respectively. In contrast, the RIBE was observed through the radioadaptive response (RAR), which was developed against a subsequent challenging dose that was applied at 10 hpf when <0.2% and <0.3% of the cells of 5 hpf zebrafish embryos were exposed to a priming dose, which was provided by microbeam protons and broad-beam alpha particles, respectively. Finally, a perspective on the field, the need for future studies and the significance of such studies were discussed. PMID:24176822

  16. The effect of ionizing radiation on amino acids and bacterial spores in different geo- and cosmochemical environments

    NASA Astrophysics Data System (ADS)

    Kminek, Gerhard

    In this thesis I have investigated the impact of ionizing radiation from the environment on the stability of bacterial spores and amino acids. I measured the radiolysis constant of amino acids and the inactivation constant of bacterial spores. To put these results in the context of a natural setting, I have selected four different cases and calculated the radiation environment for meteorites, the Martian subsurface, terrestrial halite fluid inclusions, and fossil bones. Bacterial spores exhibit a remarkable resistance to adverse environments and are the best example for the long-term survival of life forms. On a molecular level, amino acids are of particular interest because of their importance in biochemistry and their stability in the environment. The significance of amino acids, however, goes back to a time before life existed. The exogenous delivery of amino acids by meteorites might have been essential to provide the required supply of organic molecules for the origin of life on the Earth. There is one common threat, however, to the preservation of amino acids and bacterial spores in all known terrestrial and extraterrestrial environments: ionizing radiation. Amino acids in meteorites are exposed to radiation from internal radioactivity and space radiation. I show that this radiation decomposes substantial amounts of amino acids over time, indicating a higher exogenous delivery of amino acids to the early Earth. The total radiodecomposition since the synthesis of amino acids is between 23 and 68%. Radiodecomposition induces a certain fractionation in favor of smaller amino acids. Fossil bones show a post-mortem uranium uptake. My results suggest a substantial radiodecomposition of amino acids on a 10 million year time scale. Age determination based on racemization of amino acids will be affected in fossil bones that are older than 1--30 million years. My results on the stability of bacterial spores in halite fluid inclusions and on Mars suggest that radiation

  17. Preventive or Potential Therapeutic Value of Nutraceuticals against Ionizing Radiation-Induced Oxidative Stress in Exposed Subjects and Frequent Fliers

    PubMed Central

    Giardi, Maria Teresa; Touloupakis, Eleftherios; Bertolotto, Delfina; Mascetti, Gabriele

    2013-01-01

    Humans are constantly exposed to ionizing radiation deriving from outer space sources or activities related to medical care. Absorption of ionizing radiation doses over a prolonged period of time can result in oxidative damage and cellular dysfunction inducing several diseases, especially in ageing subjects. In this report, we analyze the effects of ionizing radiation, particularly at low doses, in relation to a variety of human pathologies, including cancer, and cardiovascular and retinal diseases. We discuss scientific data in support of protection strategies by safe antioxidant formulations that can provide preventive or potential therapeutic value in response to long-term diseases that may develop following exposure. PMID:23965979

  18. High-Resolution Emission-Line Imaging of Seyfert Galaxies. II. Evidence for Anisotropic Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Wilson, Andrew S.; Ward, Martin J.; Haniff, Christopher A.

    1988-11-01

    In the preceding paper, we describe a direct imaging survey of Seyfert galaxies with "linear" radio structures and find that the major axes and spatial scales of the circumnuclear emission-line gas are very similar to those of the radio continuum sources. In the present paper, the nature of this close connection between thermal and relativistic gases is assessed in detail. Models in which the kinetic energy of the radio jets or plasmoids powers shock waves, which ionize the gas, seem energetically feasible but disagree with the off-nuclear line intensity ratios. Ionization by relativistic electrons is negligible, but they may contribute to the heating of the gas. We favor a scenario in which the radio jets and plasmoids shock, accelerate, and compress ambient and entrained gas, but the dominant source of ionization is the nonstellar nuclear ultraviolet continuum. This ultraviolet source appears to be partially beamed along the axis of the radio jet. Photoionization by ultraviolet synchrotron radiation generated via shocks in the ejecta may also contribute, especially in Seyfert 2 galaxies. A comparison between the number of ionizing photons, N_i_, inferred by extrapolation of the directly observed continuum, and the number of ionizing photons, N_Hβ_, required to generate the Hβ emission has been made for six galaxies in our sample. In at least two galaxies, we find N_i_ << N_Hβ_, suggesting that the gas is exposed to a higher ionizing flux than inferred from direct observations of the nucleus, and supporting the idea of partial beaming. Similarly, the energy in the continuum between 100 A and 1 micron, if emitted isotropically, is inadequate to fuel the thermal nuclear infrared sources, implying that the radiating dust is heated by a more luminous optical-ultraviolet source. We speculate that the nuclear infrared emission of Seyfert 2 galaxies arises from dust in molecular clouds exposed to the partially beamed radiation, and we predict that the 10 micron

  19. [The reactions of the upper respiratory pathways to low doses of ionizing radiation].

    PubMed

    Gofman, V R; Povarov, Iu V; Kas'ianov, A D; Bychenko, A I

    1994-11-01

    The state of upper respiratory tract, non-specific cell resistance and immune status were studied in persons who participated in liquidation of the Chernobyl APS disaster consequences. The prolonged influence of factors caused by small doses of ionizing irradiation leads to mucosa affection of upper respiratory tract, considerable reduction of phagocytic and antiviral activity of monocytes and worsening of the immune status of organism. The data obtained during researches explains the considerable increase of ARD among these persons. PMID:7856132

  20. Membrane Signaling Induced by High Doses of Ionizing Radiation in the Endothelial Compartment. Relevance in Radiation Toxicity

    PubMed Central

    Corre, Isabelle; Guillonneau, Maëva; Paris, François

    2013-01-01

    Tumor areas can now be very precisely delimited thanks to technical progress in imaging and ballistics. This has also led to the development of novel radiotherapy protocols, delivering higher doses of ionizing radiation directly to cancer cells. Despite this, radiation toxicity in healthy tissue remains a major issue, particularly with dose-escalation in these new protocols. Acute and late tissue damage following irradiation have both been linked to the endothelium irrigating normal tissues. The molecular mechanisms involved in the endothelial response to high doses of radiation are associated with signaling from the plasma membrane, mainly via the acid sphingomyelinase/ceramide pathway. This review describes this signaling pathway and discusses the relevance of targeting endothelial signaling to protect healthy tissues from the deleterious effects of high doses of radiation. PMID:24252908

  1. A novel method involving Matlab coding to determine the distribution of a collimated ionizing radiation beam

    NASA Astrophysics Data System (ADS)

    Ioan, M.-R.

    2016-08-01

    In ionizing radiation related experiments, precisely knowing of the involved parameters it is a very important task. Some of these experiments are involving the use of electromagnetic ionizing radiation such are gamma rays and X rays, others make use of energetic charged or not charged small dimensions particles such are protons, electrons, neutrons and even, in other cases, larger accelerated particles such are helium or deuterium nuclei are used. In all these cases the beam used to hit an exposed target must be previously collimated and precisely characterized. In this paper, a novel method to determine the distribution of the collimated beam involving Matlab coding is proposed. The method was implemented by using of some Pyrex glass test samples placed in the beam where its distribution and dimension must be determined, followed by taking high quality pictures of them and then by digital processing the resulted images. By this method, information regarding the doses absorbed in the exposed samples volume are obtained too.

  2. Technical specifications manual for the MARK-1 pulsed ionizing radiation detection system. Volume 1

    SciTech Connect

    Lawrence, R.S.; Harker, Y.D.; Jones, J.L.; Hoggan, J.M.

    1993-03-01

    The MARK-1 detection system was developed by the Idaho National Engineering Laboratory for the US Department of Energy Office of Arms Control and Nonproliferation. The completely portable system was designed for the detection and analysis of intense photon emissions from pulsed ionizing radiation sources. This manual presents the technical design specifications for the MARK-1 detection system and was written primarily to assist the support or service technician in the service, calibration, and repair of the system. The manual presents the general detection system theory, the MARK-1 component design specifications, the acquisition and control software, the data processing sequence, and the system calibration procedure. A second manual entitled: Volume 2: Operations Manual for the MARK-1 Pulsed Ionizing Radiation Detection System (USDOE Report WINCO-1108, September 1992) provides a general operational description of the MARK-1 detection system. The Operations Manual was written primarily to assist the field operator in system operations and analysis of the data.

  3. Resonance-enhanced two-photon ionization of ions by Lyman alpha radiation in gaseous nebulae.

    PubMed

    Johansson, S; Letokhov, V

    2001-01-26

    One of the mysteries of nebulae in the vicinity of bright stars is the appearance of bright emission spectral lines of ions, which imply fairly high excitation temperatures. We suggest that an ion formation mechanism, based on resonance-enhanced two-photon ionization (RETPI) by intense H Lyman alpha radiation (wavelength of 1215 angstroms) trapped inside optically thick nebulae, can produce these spectral lines. The rate of such an ionization process is high enough for rarefied gaseous media where the recombination rate of the ions formed can be 10(-6) to 10(-8) per second for an electron density of 10(3) to 10(5) per cubic centimeter in the nebula. Under such conditions, the photo-ions formed may subsequently undergo further RETPI, catalyzed by intense He i and He ii radiation, which also gets enhanced in optically thick nebulae that contain enough helium. PMID:11158669

  4. Quantum mechanical theory of collisional ionization in the presence of intense laser radiation

    NASA Technical Reports Server (NTRS)

    Bellum, J. C.; George, T. F.

    1978-01-01

    The paper presents a quantum mechanical formalism for treating ionizing collisions occurring in the presence of an intense laser field. Both the intense laser radiation and the internal electronic continuum states associated with the emitted electrons are rigorously taken into account by combining discretization techniques with expansions in terms of electronic-field representations for the quasi-molecule-plus-photon system. The procedure leads to a coupled-channel description of the heavy-particle dynamics which involves effective electronic-field potential surfaces and continua. It is suggested that laser-influenced ionizing collisions can be studied to verify the effects of intense laser radiation on inelastic collisional processes. Calculation procedures for electronic transition dipole matrix elements between discrete and continuum electronic states are outlined.

  5. A Dynamic/Anisotropic Low Earth Orbit (LEO) Ionizing Radiation Model

    NASA Technical Reports Server (NTRS)

    Badavi, Francis F.; West, Katie J.; Nealy, John E.; Wilson, John W.; Abrahms, Briana L.; Luetke, Nathan J.

    2006-01-01

    The International Space Station (ISS) provides the proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the experimental validation of ionizing radiation environmental models, nuclear transport code algorithms, and nuclear reaction cross sections. Indeed, prior measurements on the Space Transportation System (STS; Shuttle) have provided vital information impacting both the environmental models and the nuclear transport code development by requiring dynamic models of the Low Earth Orbit (LEO) environment. Previous studies using Computer Aided Design (CAD) models of the evolving ISS configurations with Thermo Luminescent Detector (TLD) area monitors, demonstrated that computational dosimetry requires environmental models with accurate non-isotropic as well as dynamic behavior, detailed information on rack loading, and an accurate 6 degree of freedom (DOF) description of ISS trajectory and orientation.

  6. Synergistic effect of ionizing radiation on chemical disinfectant treatments for reduction of natural microflora on seafood

    NASA Astrophysics Data System (ADS)

    Kim, Hyunjoo; Ha, Ji-Hyoung; Lee, Ju-Woon; Jo, Cheorun; Ha, Sang-Do

    2012-08-01

    The purpose of this study was to determine whether combined treatments would produce synergistic disinfection effects on seafood products such as mussel and squid compared with single treatments. We investigated the bactericidal effects of chlorine and ionizing radiation on the natural microflora of mussel and squid. Total aerobic bacteria initially ranged from 102 to 104 Log CFU/g. More than 100 ppm of chlorine and irradiation at 1 kGy were sufficient to reduce the total aerobic bacteria on mussel and squid to a level lower than detection limit (10 CFU/g). Synergistic effects against natural microflora were observed for all combined treatment. These results suggest that a significant synergistic benefit results from combine chlorine-ionizing radiation treatment against natural microflora on mussel and squid.

  7. A Role for Bioelectric Effects in the Induction of Bystander Signals by Ionizing Radiation?

    PubMed Central

    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

  8. The iQID camera: An ionizing-radiation quantum imaging detector

    PubMed Central

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Barber, H. Bradford; Furenlid, Lars R.

    2015-01-01

    We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detector’s response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The confirmed response to this broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated by particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. The spatial location and energy of individual particles are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, excellent detection efficiency for charged particles, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discriminate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is real-time, single-particle digital autoradiography. We present the latest results and discuss potential applications. PMID:26166921

  9. The iQID Camera: An Ionizing-Radiation Quantum Imaging Detector

    SciTech Connect

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Barber, Bradford H.; Furenlid, Lars R.

    2014-06-11

    We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detectors response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The detector’s response to a broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. Individual particles are identified and their spatial position (to sub-pixel accuracy) and energy are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, high sensitivity, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discrimate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is single-particle, real-time digital autoradiography. In conclusion, we present the latest results and discuss potential applications.

  10. Influence of ionizing radiation on the mechanical properties of BisGMA/TEGDMA based experimental resin

    NASA Astrophysics Data System (ADS)

    LMP, Campos; Boaro, LC; LKG, Santos; Parra, DF; Lugão, AB

    2015-10-01

    Dental restorative composites are activated by visible light and the polymerization process, known as direct technique, is initiated by absorbing light in a specific wavelength range (450-500 nm). However this technique presented some disadvantages. If light is not inserted correctly, layers uncured can cause countless damage to restoration, especially with regard to mechanical properties. A clinical alternative used to reduce the shortcomings of direct application is the use of composite resins for indirect application. These composites are adaptations of resins prepared for direct use, with differences mainly in the healing process. Besides the traditional photoactivation, indirect application composites may be submitted to particular curing conditions, such as a slow curing rate, heating, vacuum, and inert-gas pressure leading to an oxygen-free environment. However few studies have been conducted on the process of post-curing by ionizing radiation at low doses. On this sense the purpose of this study was to evaluate possible interactions of ionizing radiation in the post-curing process of the experimental composites based on BisGMA/TEGDMA filled with silica Aerosil OX-50 silanized. Characterization of the experimental composites was performed by thermogravimetry analysis, infrared spectroscopy, elastic modulus and flexural strength. Statistical analysis of results was calculated by one-way ANOVA/Tukey's test. Cross-linking of the polymeric matrix caused by ionizing radiation, influenced the thermal stability of irradiated specimens. FTIR analysis showed that the ionizing radiation induced a post-cure reaction in the specimens. The irradiation dose influenced directly the mechanical properties that showed a strong positive correlation between flexural strength and irradiation and between modulus strength and irradiation.

  11. Resource Letter EIRLD-2: Effects of Ionizing Radiation at Low Doses

    NASA Astrophysics Data System (ADS)

    Wilson, Richard

    2012-04-01

    This Resource Letter provides a guide to the literature on the effects of ionizing radiation on people at low doses. Journal articles, books and web pages are provided for the following: data at high dose levels, effects of moderate to high doses (leukemia, solid cancer, lung cancer, childhood cancer, and non-cancer outcomes), effects of dose rate, relationship to background, supra linearity and hormesis, and policy implications.

  12. Resource Letter EIRLD-1: Effects of ionizing radiation at low doses

    NASA Astrophysics Data System (ADS)

    Wilson, Richard

    1999-05-01

    This Resource Letter provides a guide to the literature on the effects of ionizing radiation on people at low doses. Journal articles, books, and web pages are provided for the following: data at high dose levels, effects of moderate to high doses (leukemia, solid cancer, lung cancer, childhood cancer and noncancer outcomes), effects of dose rate, relationship to background, supra linearity and homesis, and policy implications.

  13. Effects of autogamy in Paramecium tetraurelia on catalase activity and on radiosensitivity to natural ionizing radiations

    SciTech Connect

    Croute, F.; Dupouy, D.; Charley, J.P.; Soleilhavoup, J.P.; Planel, H.

    1980-02-01

    Catalase activity of Paramecium tetraurelia decreased during autogamy and recovered to normal 5 days later. Autogamy also caused changes in the ciliate's sensitivity sensitivity to natural ionizing radiations - the decrease in cell growth rate previously described in shielded cultures did not occur when autogamous cells were used. Maximum effect of shielding was observed in 11-day-old postautogamous cells. The role of the catalase in the mechanism of natural irradiation effect is discussed.

  14. The study of ionizing radiation effects on polypropylene and rice husk ash composite

    NASA Astrophysics Data System (ADS)

    Alfaro, E. F.; Dias, D. B.; Silva, L. G. A.

    2013-03-01

    The aim of this work was to study the ionizing radiation effects on polypropylene/20% of rice husk ash composites. The composites were irradiated by electron beam at different doses and the mechanical and thermal properties were evaluated using tensile strength, Izod impact, hardness, softening temperature, differential scanning calorimetry (DSC) and thermogravimetry (TG). The results showed that the properties decreased by increasing irradiation dose due to chain scission.

  15. The iQID Camera: An Ionizing-Radiation Quantum Imaging Detector

    DOE PAGESBeta

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Barber, Bradford H.; Furenlid, Lars R.

    2014-06-11

    We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detectors response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The detector’s response to a broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated particle interactions is optically amplified by the intensifier andmore » then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. Individual particles are identified and their spatial position (to sub-pixel accuracy) and energy are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, high sensitivity, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discrimate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is single-particle, real-time digital autoradiography. In conclusion, we present the latest results and discuss potential applications.« less

  16. The iQID camera: An ionizing-radiation quantum imaging detector

    NASA Astrophysics Data System (ADS)

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Bradford Barber, H.; Furenlid, Lars R.

    2014-12-01

    We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detector's response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The confirmed response to this broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated by particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. The spatial location and energy of individual particles are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, excellent detection efficiency for charged particles, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discriminate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is real-time, single-particle digital autoradiography. We present the latest results and discuss potential applications.

  17. The iQID Camera An Ionizing-Radiation Quantum Imaging Detector

    SciTech Connect

    Miller, Brian W.; Gregory, Stephanie J.; Fuller, Erin S.; Barrett, Harrison H.; Barber, Bradford H.; Furenlid, Lars R.

    2014-06-11

    Abstract We have developed and tested a novel, ionizing-radiation Quantum Imaging Detector (iQID). This scintillation-based detector was originally developed as a high-resolution gamma-ray imager, called BazookaSPECT, for use in single-photon emission computed tomography (SPECT). Recently, we have investigated the detectors response and imaging potential with other forms of ionizing radiation including alpha, neutron, beta, and fission fragment particles. The detector’s response to a broad range of ionizing radiation has prompted its new title. The principle operation of the iQID camera involves coupling a scintillator to an image intensifier. The scintillation light generated particle interactions is optically amplified by the intensifier and then re-imaged onto a CCD/CMOS camera sensor. The intensifier provides sufficient optical gain that practically any CCD/CMOS camera can be used to image ionizing radiation. Individual particles are identified and their spatial position (to sub-pixel accuracy) and energy are estimated on an event-by-event basis in real time using image analysis algorithms on high-performance graphics processing hardware. Distinguishing features of the iQID camera include portability, large active areas, high sensitivity, and high spatial resolution (tens of microns). Although modest, iQID has energy resolution that is sufficient to discrimate between particles. Additionally, spatial features of individual events can be used for particle discrimination. An important iQID imaging application that has recently been developed is single-particle, real-time digital autoradiography. We present the latest results and discuss potential applications.

  18. Water-dispersable colloidal quantum dots for the detection of ionizing radiation.

    PubMed

    Lecavalier, Marie-Eve; Goulet, Mathieu; Allen, Claudine Nì; Beaulieu, Luc; Larivière, Dominic

    2013-12-25

    Fluorescent CdSe-CdS-Cd0.5Zn0.5S-ZnS core-shell colloidal quantum dots (cQDs) dispersed in aqueous and organic solvents have been prepared and used as scintillators for detecting ionizing radiation. Results demonstrate a linear relationship between emitted luminescence and dose-activity. These results suggest that cQDs alone could be used as liquid scintillators for specific environmental and medical applications. PMID:24177415

  19. Preparation and characterization of a novel ionizing electromagnetic radiation shielding material: Hematite filled polyester based composites

    NASA Astrophysics Data System (ADS)

    Eren Belgin, E.; Aycik, G. A.; Kalemtas, A.; Pelit, A.; Dilek, D. A.; Kavak, M. T.

    2015-10-01

    Isophthalic polyester (PES) based and natural mineral (hematite) filled composites were prepared and characterized for ionizing electromagnetic radiation shielding applications. Density evaluation and microscopic studies of the composites were carried out. Shielding performances of the composites were investigated for three different IEMR energy regions as low, intermediate and high. The mass attenuation coefficient of the prepared composites reached 98% of the elemental lead. In addition, the studied composites were superior to lead by virtue of their non-toxic nature.

  20. Intelligent monitor functional model with ionization chamber for mixed nuclear radiation field measurements

    SciTech Connect

    Valcov, N.; Purghel, L.; Celarel, A.

    1998-12-31

    By using the statistical discrimination technique, the components of an ionization current, due to a mixed radiation field, may be simultaneously measured. A functional model, including a series manufactured gamma-ray ratemeter was done, as an intermediate step in the design of specialized nuclear instrumentation, in order to check the concept of statistical discrimination method. The obtained results are in good agreement with the estimations of the statistical discrimination method.

  1. Semen Abnormalities, Sperm DNA Damage and Global Hypermethylation in Health Workers Occupationally Exposed to Ionizing Radiation

    PubMed Central

    Kumar, Dayanidhi; Salian, Sujith Raj; Kalthur, Guruprasad; Uppangala, Shubhashree; Kumari, Sandhya; Challapalli, Srinivas; Chandraguthi, Srinidhi Gururajarao; Krishnamurthy, Hanumanthappa; Jain, Navya; Kumar, Pratap; Adiga, Satish Kumar

    2013-01-01

    Background Cytogenetic studies have demonstrated that low levels of chronic radiation exposure can potentially increase the frequency of chromosomal aberrations and aneuploidy in somatic cells. Epidemiological studies have shown that health workers occupationally exposed to ionizing radiation bear an increased risk of hematological malignancies. Objectives To find the influence of occupational radiation exposure on semen characteristics, including genetic and epigenetic integrity of spermatozoa in a chronically exposed population. Methods This cross sectional study included 134 male volunteers of which 83 were occupationally exposed to ionizing radiation and 51 were non-exposed control subjects. Semen characteristics, sperm DNA fragmentation, aneuploidy and incidence of global hypermethylation in the spermatozoa were determined and compared between the non-exposed and the exposed group. Results Direct comparison of the semen characteristics between the non-exposed and the exposed population revealed significant differences in motility characteristics, viability, and morphological abnormalities (P<0.05–0.0001). Although, the level of sperm DNA fragmentation was significantly higher in the exposed group as compared to the non-exposed group (P<0.05–0.0001), the incidence of sperm aneuploidy was not statistically different between the two groups. However, a significant number of hypermethylated spermatozoa were observed in the exposed group in comparison to non-exposed group (P<0.05). Conclusions We provide the first evidence on the detrimental effects of occupational radiation exposure on functional, genetic and epigenetic integrity of sperm in health workers. However, further studies are required to confirm the potential detrimental effects of ionizing radiation in these subjects. PMID:23922858

  2. Spatiotemporal characterization of ionizing radiation induced DNA damage foci and their relation to chromatin organization

    SciTech Connect

    Costes, Sylvain V; Chiolo, Irene; Pluth, Janice M.; Barcellos-Hoff, Mary Helen; Jakob, Burkhard

    2009-09-15

    DNA damage sensing proteins have been shown to localize to the sites of DSB within seconds to minutes following ionizing radiation (IR) exposure, resulting in the formation of microscopically visible nuclear domains referred to as radiation-induced foci (RIF). This review characterizes the spatio-temporal properties of RIF at physiological doses, minutes to hours following exposure to ionizing radiation, and it proposes a model describing RIF formation and resolution as a function of radiation quality and nuclear densities. Discussion is limited to RIF formed by three interrelated proteins ATM (Ataxia telangiectasia mutated), 53BP1 (p53 binding protein 1) and ?H2AX (phosphorylated variant histone H2AX). Early post-IR, we propose that RIF mark chromatin reorganization, leading to a local nuclear scaffold rigid enough to keep broken DNA from diffusing away, but open enough to allow the repair machinery. We review data indicating clear kinetic and physical differences between RIF emerging from dense and uncondensed regions of the nucleus. At later time post-IR, we propose that persistent RIF observed days following exposure to ionizing radiation are nuclear ?scars? marking permanent disruption of the chromatin architecture. When DNA damage is resolved, such chromatin modifications should not necessarily lead to growth arrest and it has been shown that persistent RIF can replicate during mitosis. Thus, heritable persistent RIF spanning over tens of Mbp may affect the transcriptome of a large progeny of cells. This opens the door for a non DNA mutation-based mechanism of radiation-induced phenotypes.

  3. Quantitative Proteomic Profiling of Low Dose Ionizing Radiation Effects in a Human Skin Model

    SciTech Connect

    Hengel, Shawna; Aldrich, Joshua T.; Waters, Katrina M.; Pasa-Tolic, Ljiljana; Stenoien, David L.

    2014-07-29

    To assess molecular responses to low doses of radiation that may be encountered during medical diagnostic procedures, nuclear accidents, or terrorist acts, a quantitative global proteomic approach was used to identify protein alterations in a reconstituted human skin tissue treated with 10 cGy of ionizing radiation. Subcellular fractionation was employed to remove highly abundant structural proteins and provide insight on radiation induced alterations in protein abundance and localization. In addition, peptides were post-fractionated using high resolution 2-dimensional liquid chromatography to increase the dynamic range of detection of protein abundance and translocation changes. Quantitative data was obtained by labeling peptides with 8-plex isobaric iTRAQ tags. A total of 207 proteins were detected with statistically significant alterations in abundance and/or subcellular localization compared to sham irradiated tissues. Bioinformatics analysis of the data indicated that the top canonical pathways affected by low dose radiation are related to cellular metabolism. Among the proteins showing alterations in abundance, localization and proteolytic processing was the skin barrier protein filaggrin which is consistent with our previous observation that ionizing radiation alters profilaggrin processing with potential effects on skin barrier functions. In addition, a large number of proteases and protease regulators were affected by low dose radiation exposure indicating that altered proteolytic activity may be a hallmark of low dose radiation exposure. While several studies have demonstrated altered transcriptional regulation occurs following low dose radiation exposures, the data presented here indicates post-transcriptional regulation of protein abundance, localization, and proteolytic processing play an important role in regulating radiation responses in complex human tissues.

  4. Improvements to the Ionizing Radiation Risk Assessment Program for NASA Astronauts

    NASA Technical Reports Server (NTRS)

    Semones, E. J.; Bahadori, A. A.; Picco, C. E.; Shavers, M. R.; Flores-McLaughlin, J.

    2011-01-01

    To perform dosimetry and risk assessment, NASA collects astronaut ionizing radiation exposure data from space flight, medical imaging and therapy, aviation training activities and prior occupational exposure histories. Career risk of exposure induced death (REID) from radiation is limited to 3 percent at a 95 percent confidence level. The Radiation Health Office at Johnson Space Center (JSC) is implementing a program to integrate the gathering, storage, analysis and reporting of astronaut ionizing radiation dose and risk data and records. This work has several motivations, including more efficient analyses and greater flexibility in testing and adopting new methods for evaluating risks. The foundation for these improvements is a set of software tools called the Astronaut Radiation Exposure Analysis System (AREAS). AREAS is a series of MATLAB(Registered TradeMark)-based dose and risk analysis modules that interface with an enterprise level SQL Server database by means of a secure web service. It communicates with other JSC medical and space weather databases to maintain data integrity and consistency across systems. AREAS is part of a larger NASA Space Medicine effort, the Mission Medical Integration Strategy, with the goal of collecting accurate, high-quality and detailed astronaut health data, and then securely, timely and reliably presenting it to medical support personnel. The modular approach to the AREAS design accommodates past, current, and future sources of data from active and passive detectors, space radiation transport algorithms, computational phantoms and cancer risk models. Revisions of the cancer risk model, new radiation detection equipment and improved anthropomorphic computational phantoms can be incorporated. Notable hardware updates include the Radiation Environment Monitor (which uses Medipix technology to report real-time, on-board dosimetry measurements), an updated Tissue-Equivalent Proportional Counter, and the Southwest Research Institute

  5. Mechanical loading causes site-specific anabolic effects on bone following exposure to ionizing radiation.

    PubMed

    Shirazi-Fard, Yasaman; Alwood, Joshua S; Schreurs, Ann-Sofie; Castillo, Alesha B; Globus, Ruth K

    2015-12-01

    During spaceflight, astronauts will be exposed to a complex mixture of ionizing radiation that poses a risk to their health. Exposure of rodents to ionizing radiation on Earth causes bone loss and increases osteoclasts in cancellous tissue, but also may cause persistent damage to stem cells and osteoprogenitors. We hypothesized that ionizing radiation damages skeletal tissue despite a prolonged recovery period, and depletes the ability of cells in the osteoblast lineage to respond at a later time. The goal of the current study was to test if irradiation prevents bone accrual and bone formation induced by an anabolic mechanical stimulus. Tibial axial compression was used as an anabolic stimulus after irradiation with heavy ions. Mice (male, C57BL/6J, 16 weeks) were exposed to high atomic number, high energy (HZE) iron ions ((56)Fe, 2 Gy, 600 MeV/ion) (IR, n=5) or sham-irradiated (Sham, n=5). In vivo axial loading was initiated 5 months post-irradiation; right tibiae in anesthetized mice were subjected to an established protocol known to stimulate bone formation (cyclic 9N compressive pulse, 60 cycles/day, 3 day/wk for 4 weeks). In vivo data showed no difference due to irradiation in the apparent stiffness of the lower limb at the initiation of the axial loading regimen. Axial loading increased cancellous bone volume by microcomputed tomography and bone formation rate by histomorphometry in both sham and irradiated animals, with a main effect of axial loading determined by two-factor ANOVA with repeated measure. There were no effects of radiation in cancellous bone microarchitecture and indices of bone formation. At the tibia diaphysis, results also revealed a main effect of axial loading on structure. Furthermore, irradiation prevented axial loading-induced stimulation of bone formation rate at the periosteal surface of cortical tissue. In summary, axial loading stimulated the net accrual of cancellous and cortical mass and increased cancellous bone formation rate

  6. RUNAWAY STARS AND THE ESCAPE OF IONIZING RADIATION FROM HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Conroy, Charlie; Kratter, Kaitlin M.

    2012-08-20

    Approximately 30% of all massive stars in the Galaxy are runaways with velocities exceeding 30 km s{sup -1}. Their high speeds allow them to travel {approx}0.1-1 kpc away from their birthplace before they explode at the end of their several Myr lifetimes. At high redshift, when galaxies were much smaller than in the local universe, runaways could venture far from the dense inner regions of their host galaxies. From these large radii, and therefore low column densities, much of their ionizing radiation is able to escape into the intergalactic medium. Runaways may therefore significantly enhance the overall escape fraction of ionizing radiation, f{sub esc}, from small galaxies at high redshift. We present simple models of the high-redshift runaway population and its impact on f{sub esc} as a function of halo mass, size, and redshift. We find that the inclusion of runaways enhances f{sub esc} by factors of Almost-Equal-To 1.1-8, depending on halo mass, galaxy geometry, and the mechanism of runaway production, implying that runaways may contribute 50%-90% of the total ionizing radiation escaping from high-redshift galaxies. Runaways may therefore play an important role in reionizing the universe.

  7. Improved Intratumoral Oxygenation Through Vascular Normalization Increases Glioma Sensitivity to Ionizing Radiation

    SciTech Connect

    McGee, Mackenzie C.; Hamner, J. Blair; Williams, Regan F.; Rosati, Shannon F.; Sims, Thomas L.; Ng, Catherine Y.; Gaber, M. Waleed; Calabrese, Christopher; Wu Jianrong; Nathwani, Amit C.; Merchant, Thomas E.; Davidoff, Andrew M.

    2010-04-15

    Purpose: Ionizing radiation, an important component of glioma therapy, is critically dependent on tumor oxygenation. However, gliomas are notable for areas of necrosis and hypoxia, which foster radioresistance. We hypothesized that pharmacologic manipulation of the typically dysfunctional tumor vasculature would improve intratumoral oxygenation and, thus, the antiglioma efficacy of ionizing radiation. Methods and Materials: Orthotopic U87 xenografts were treated with either continuous interferon-beta (IFN-beta) or bevacizumab, alone, or combined with cranial irradiation (RT). Tumor growth was assessed by quantitative bioluminescence imaging; the tumor vasculature using immunohistochemical staining, and tumor oxygenation using hypoxyprobe staining. Results: Both IFN-beta and bevaziumab profoundly affected the tumor vasculature, albeit with different cellular phenotypes. IFN-beta caused a doubling in the percentage of area of perivascular cell staining, and bevacizumab caused a rapid decrease in the percentage of area of endothelial cell staining. However, both agents increased intratumoral oxygenation, although with bevacizumab, the effect was transient, being lost by 5 days. Administration of IFN-beta or bevacizumab before RT was significantly more effective than any of the three modalities as monotherapy or when RT was administered concomitantly with IFN-beta or bevacizumab or 5 days after bevacizumab. Conclusion: Bevacizumab and continuous delivery of IFN-beta each induced significant changes in glioma vascular physiology, improving intratumoral oxygenation and enhancing the antitumor activity of ionizing radiation. Additional investigation into the use and timing of these and other agents that modify the vascular phenotype, combined with RT, is warranted to optimize cytotoxic activity.

  8. Modeling hematopoietic system response caused by chronic exposure to ionizing radiation

    PubMed Central

    Akushevich, Igor V.; Veremeyeva, Galina A.; Dimov, Georgy P.; Ukraintseva, Svetlana V.; Arbeev, Konstantin G.; Akleyev, Alexander V.; Yashin, Anatoly I.

    2013-01-01

    A new model of the hematopoietic system response in humans chronically exposed to ionizing radiation describes the dynamics of the hematopoietic stem cell compartment as well as the dynamics of each of the four blood cell types (lymphocytes, neutrophiles, erythrocytes, and platelets). The required model parameters were estimated based on available results of human and experimental animal studies. They include the steady-state number of hematopoietic stem cells and peripheral blood cell lines in an unexposed organism, amplification parameters for each blood line, parameters describing proliferation and apoptosis, parameters of feedback functions regulating the steady-state numbers, and characteristics of radiosensitivity related to cell death and non-lethal cell damage. The model predictions were tested using data on hematological measurements (e.g., blood counts) performed in 1950–1956 in the Techa River residents chronically exposed to ionizing radiation since 1949. The suggested model of hematopoiesis is capable of describing experimental findings in the Techa River Cohort, including: i) slopes of the dose-effect curves reflecting the inhibition of hematopoiesis due to chronic ionizing radiation, ii) delay in effect of chronic exposure and accumulated character of the effect, and iii) dose-rate patterns for different cytopenic states (e.g., leukopenia, thrombocytopenia). PMID:21259022

  9. SEM analysis of ionizing radiation effects in linear integrated circuits. [Scanning Electron Microscope

    NASA Technical Reports Server (NTRS)

    Stanley, A. G.; Gauthier, M. K.

    1977-01-01

    A successful diagnostic technique was developed using a scanning electron microscope (SEM) as a precision tool to determine ionization effects in integrated circuits. Previous SEM methods radiated the entire semiconductor chip or major areas. The large area exposure methods do not reveal the exact components which are sensitive to radiation. To locate these sensitive components a new method was developed, which consisted in successively irradiating selected components on the device chip with equal doses of electrons /10 to the 6th rad (Si)/, while the whole device was subjected to representative bias conditions. A suitable device parameter was measured in situ after each successive irradiation with the beam off.

  10. Evaluation of fluorescent dye degradation indirectly induced by x-ray ionizing radiation.

    PubMed

    Benevides, Clayton Augusto; Duarte de Menezes, Frederico; de Araujo, Renato E

    2015-08-01

    This work evaluated the fluorescent dye degradation indirectly induced by ionizing radiation with high energy photons (50 keV). Aqueous gels of agarose with low concentrations of Rhodamine 6G and Fluorescein were submitted to doses of x-ray radiation up to 200 Gy. The dye degradation was analyzed by fluorescence spectroscopy, using an excitation light-emitting diode with a peak wavelength of 462 nm. A rate equation model of fluorophores and radicals' species populations was developed to describe the degradation time behavior of the fluorescent solutions. The model suggests fluorescent dyes should be used in dosimetry. PMID:26368112

  11. Dried plum diet protects from bone loss caused by ionizing radiation

    DOE PAGESBeta

    Schreurs, A. -S.; Shirazi-Fard, Y.; Shahnazari, M.; Alwood, J. S.; Truong, T. A.; Tahimic, C. G. T.; Limoli, C. L.; Turner, N. D.; Halloran, B.; Globus, R. K.

    2016-02-11

    Bone loss caused by ionizing radiation is a potential health concern for radiotherapy patients, radiation workers and astronauts. In animal studies, exposure to ionizing radiation increases oxidative damage in skeletal tissues, and results in an imbalance in bone remodeling initiated by increased bone-resorbing osteoclasts. Therefore, we evaluated various candidate interventions with antioxidant or antiinflammatory activities (antioxidant cocktail, dihydrolipoic acid, ibuprofen, dried plum) both for their ability to blunt the expression of resorption-related genes in marrow cells after irradiation with either gamma rays (photons, 2 Gy) or simulated space radiation (protons and heavy ions, 1 Gy) and to prevent bone loss.more » Dried plum was most effective in reducing the expression of genes related to bone resorption (Nfe2l2, Rankl, Mcp1, Opg, TNF-α) and also preventing later cancellous bone decrements caused by irradiation with either photons or heavy ions. Furthermore, dietary supplementation with DP may prevent the skeletal effects of radiation exposures either in space or on Earth.« less

  12. Bystander effects of ionizing radiation can be modulated by signaling amines

    SciTech Connect

    Poon, R.C.C.; Agnihotri, N.; Seymour, C.; Mothersill, C.

    2007-10-15

    Actual risk and risk management of exposure to ionizing radiation are among the most controversial areas in environmental health protection. Recent developments in radiobiology especially characterization of bystander effects have called into question established dogmas and are thought to cast doubt on the scientific basis of the risk assessment framework, leading to uncertainty for regulators and concern among affected populations. In this paper we test the hypothesis that small signaling molecules widely used throughout the animal kingdom for signaling stress or environmental change, such as 5-Hydroxytryptamine (5-HT, serotonin), L-DOPA, glycine or nicotine are involved in bystander signaling processes following ionizing radiation exposure. We report data which suggest that nano to micromolar concentrations of these agents can modulate bystander-induced cell death. Depletion of 5-HT present in tissue culture medium, occurred following irradiation of cells. This suggested that 5-HT might be bound by membrane receptors after irradiation. Expression of 5-HT type 3 receptors which are Ca{sup 2+} ion channels was confirmed in the cells using immunocytochemistry and receptor expression could be increased using radiation or 5-HT exposure. Zofran and Kitryl, inhibitors of 5-HT type 3 receptors, and reserpine a generic serotonin antagonist block the bystander effect induced by radiation or by serotonin. The results may be important for the mechanistic understanding of how low doses of radiation interact with cells to produce biological effects.

  13. Dried plum diet protects from bone loss caused by ionizing radiation.

    PubMed

    Schreurs, A-S; Shirazi-Fard, Y; Shahnazari, M; Alwood, J S; Truong, T A; Tahimic, C G T; Limoli, C L; Turner, N D; Halloran, B; Globus, R K

    2016-01-01

    Bone loss caused by ionizing radiation is a potential health concern for radiotherapy patients, radiation workers and astronauts. In animal studies, exposure to ionizing radiation increases oxidative damage in skeletal tissues, and results in an imbalance in bone remodeling initiated by increased bone-resorbing osteoclasts. Therefore, we evaluated various candidate interventions with antioxidant or anti-inflammatory activities (antioxidant cocktail, dihydrolipoic acid, ibuprofen, dried plum) both for their ability to blunt the expression of resorption-related genes in marrow cells after irradiation with either gamma rays (photons, 2 Gy) or simulated space radiation (protons and heavy ions, 1 Gy) and to prevent bone loss. Dried plum was most effective in reducing the expression of genes related to bone resorption (Nfe2l2, Rankl, Mcp1, Opg, TNF-α) and also preventing later cancellous bone decrements caused by irradiation with either photons or heavy ions. Thus, dietary supplementation with DP may prevent the skeletal effects of radiation exposures either in space or on Earth. PMID:26867002

  14. Dried plum diet protects from bone loss caused by ionizing radiation

    PubMed Central

    Schreurs, A.-S.; Shirazi-Fard, Y.; Shahnazari, M.; Alwood, J. S.; Truong, T. A.; Tahimic, C. G. T.; Limoli, C. L.; Turner, N. D.; Halloran, B.; Globus, R. K.

    2016-01-01

    Bone loss caused by ionizing radiation is a potential health concern for radiotherapy patients, radiation workers and astronauts. In animal studies, exposure to ionizing radiation increases oxidative damage in skeletal tissues, and results in an imbalance in bone remodeling initiated by increased bone-resorbing osteoclasts. Therefore, we evaluated various candidate interventions with antioxidant or anti-inflammatory activities (antioxidant cocktail, dihydrolipoic acid, ibuprofen, dried plum) both for their ability to blunt the expression of resorption-related genes in marrow cells after irradiation with either gamma rays (photons, 2 Gy) or simulated space radiation (protons and heavy ions, 1 Gy) and to prevent bone loss. Dried plum was most effective in reducing the expression of genes related to bone resorption (Nfe2l2, Rankl, Mcp1, Opg, TNF-α) and also preventing later cancellous bone decrements caused by irradiation with either photons or heavy ions. Thus, dietary supplementation with DP may prevent the skeletal effects of radiation exposures either in space or on Earth. PMID:26867002

  15. Clustered DNA damages induced in isolated DNA and in human cells by low doses of ionizing radiation

    NASA Technical Reports Server (NTRS)

    Sutherland, B. M.; Bennett, P. V.; Sidorkina, O.; Laval, J.; Lowenstein, D. I. (Principal Investigator)

    2000-01-01

    Clustered DNA damages-two or more closely spaced damages (strand breaks, abasic sites, or oxidized bases) on opposing strands-are suspects as critical lesions producing lethal and mutagenic effects of ionizing radiation. However, as a result of the lack of methods for measuring damage clusters induced by ionizing radiation in genomic DNA, neither the frequencies of their production by physiological doses of radiation, nor their repairability, nor their biological effects are known. On the basis of methods that we developed for quantitating damages in large DNAs, we have devised and validated a way of measuring ionizing radiation-induced clustered lesions in genomic DNA, including DNA from human cells. DNA is treated with an endonuclease that induces a single-strand cleavage at an oxidized base or abasic site. If there are two closely spaced damages on opposing strands, such cleavage will reduce the size of the DNA on a nondenaturing gel. We show that ionizing radiation does induce clustered DNA damages containing abasic sites, oxidized purines, or oxidized pyrimidines. Further, the frequency of each of these cluster classes is comparable to that of frank double-strand breaks; among all complex damages induced by ionizing radiation, double-strand breaks are only about 20%, with other clustered damage constituting some 80%. We also show that even low doses (0.1-1 Gy) of high linear energy transfer ionizing radiation induce clustered damages in human cells.

  16. Adrenoreceptor development in rat cerebrum and the effects of ionizing radiation

    SciTech Connect

    Nyquist-Battie, C.; Fortney, R.; Gochee, A.

    1984-01-01

    Previous studies in the rat have shown that neonatal radiation alters certain aspects of CNS monoaminergic systems including altering cerebral norepinephrine levels (17). To determine if cerebral adrenoreceptor development is also altered by neonatal ionizing radiation, a single dose of whole body gamma-radiation was administered to rats on postnatal day two. This treatment did not alter (/sup 3/H)-dihydroalprenolol (beta adrenoreceptor) or (/sup 3/H)-WB4101 (alpha1 adrenoreceptor) binding when cerebra from irradiated animals were compared to age-matched sham-irradiated controls on postnatal days 9, 15 and 35. In contrast, (/sup 3/H)-yohimbine (alpha2-adrenoreceptor) binding was altered in gamma-irradiation, a change manifested on postnatal days 9, 15 and 35 by lower than normal receptor densities (pmoles/g wet weight of tissue) although no radiation-induced changes in K/sub D/ were apparent.

  17. Risks of exposure to ionizing and millimeter-wave radiation from airport whole-body scanners.

    PubMed

    Moulder, John E

    2012-06-01

    Considerable public concern has been expressed around the world about the radiation risks posed by the backscatter (ionizing radiation) and millimeter-wave (nonionizing radiation) whole-body scanners that have been deployed at many airports. The backscatter and millimeter-wave scanners currently deployed in the U.S. almost certainly pose negligible radiation risks if used as intended, but their safety is difficult-to-impossible to prove using publicly accessible data. The scanners are widely disliked and often feared, which is a problem made worse by what appears to be a veil of secrecy that covers their specifications and dosimetry. Therefore, for these and future similar technologies to gain wide acceptance, more openness is needed, as is independent review and regulation. Publicly accessible, and preferably peer-reviewed evidence is needed that the deployed units (not just the prototypes) meet widely-accepted safety standards. It is also critical that risk-perception issues be handled more competently. PMID:22494369

  18. Radon in the Workplace: the Occupational Safety and Health Administration (OSHA) Ionizing Radiation Standard.

    PubMed

    Lewis, Robert K

    2016-10-01

    On 29 December 1970, the Occupational Safety and Health Act of 1970 established the Occupational Safety and Health Administration (OSHA). This article on OSHA, Title 29, Part 1910.1096 Ionizing Radiation standard was written to increase awareness of the employer, the workforce, state and federal governments, and those in the radon industry who perform radon testing and radon mitigation of the existence of these regulations, particularly the radon relevant aspect of the regulations. This review paper was also written to try to explain what can sometimes be complicated regulations. As the author works within the Radon Division of the Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection, the exclusive focus of the article is on radon. The 1910.1096 standard obviously covers many other aspects of radiation and radiation safety in the work place. PMID:27575350

  19. Inactivation of human norovirus and Tulane virus in simple media and fresh whole strawberries by ionizing radiation.

    PubMed

    DiCaprio, Erin; Phantkankum, Nuttapong; Culbertson, Doug; Ma, Yuanmei; Hughes, John H; Kingsley, David; Uribe, Roberto M; Li, Jianrong

    2016-09-01

    Human norovirus (NoV) is a major cause of fresh produce-associated outbreaks and human NoV in irrigation water can potentially lead to viral internalization in fresh produce. Therefore, there is a need to develop novel intervention strategies to target internalized viral pathogens while maintaining fresh produce quality. In this study electron beam (E-beam) and gamma radiation were evaluated for efficacy against a human NoV GII.4 strain and Tulane virus (TV). Virus survival following ionizing radiation treatments was determined using direct quantitative reverse transcriptase PCR (RT-qPCR), the porcine gastric mucin magnetic bead (PGM-MB) binding assay followed by RT-qPCR, and plaque assay. In simple media, a high dose of E-beam treatment was required to completely abolish the receptor binding ability of human NoV (35.3kGy) and TV (19.5-24.1kGy), as assessed using the PGM-MB binding assay. Both human NoV and TV were more susceptible to gamma irradiation than E-beam, requiring 22.4kGy to achieve complete inactivation. In whole strawberries, no human NoV or TV RNA was detected following 28.7kGy of E-beam treatment using the PGM-MB binding assay. Overall, human NoV and TV are highly resistant to ionizing radiation and therefore the technology may not be suitable to eliminate viruses in fresh produce at the currently approved levels. In addition, the PGM-MB binding assay is an improved method to detect viral infectivity compared to direct RT-qPCR. PMID:27240219

  20. Elimination of Listeria monocytogenes from ready-to-eat turkey and cheese tortilla wraps using ionizing radiation.

    PubMed

    Sommers, Christopher H; Boyd, Glenn

    2005-01-01

    Listeria monocytogenes is a common postprocess contaminant on ready-to-eat foods including premade ready-to-eat sandwiches. One popular type of sandwich product is the tortilla wrap, which contains sliced luncheon meats and cheeses rolled within a flour tortilla. This study determined the radiation resistance of L. monocytogenes surface inoculated onto two types of commercially available wheat flour tortillas, processed cheese slices, and deli turkey meat. The D10-values for L. monocytogenes (the radiation dose required to inactivate 1 log of the pathogen) were 0.27 kGy when inoculated onto two flour tortilla types, 0.28 and 0.30 kGy when inoculated onto two types of sliced processed cheeses, and 0.58 and 0.65 kGy when inoculated onto two types of sliced deli turkey meat. When two types of tortilla wraps were assembled from the individual components and L. monocytogenes was inoculated into the interfaces between the individual components, the D10-values were 0.27 to 0.37 kGy in the tortilla and cheese interfaces, 0.33 to 0.41 kGy in the cheese and turkey interfaces, and 0.25 to 0.33 kGy in the turkey and tortilla interfaces. The ability of ionizing radiation to reduce pathogen levels on the complex tortilla, cheese, and luncheon meat product was limited by the higher radiation resistance of L. monocytogenes when inoculated onto the ready-to-eat turkey-meat component. PMID:15690820