Sample records for cells gamma radiation

  1. Influence on cell proliferation of background radiation or exposure to very low, chronic gamma radiation. [Paramecium tetraurelia; Synechococcus lividus

    SciTech Connect

    Planel, H.; Soleilhavoup, J.P.; Tixador, R.; Richoilley, G.; Conter, A.; Croute, F.; Caratero, C.; Gaubin, Y.

    1987-05-01

    Investigations carried out on the protozoan Paramecium tetraurelia and the cyanobacteria Synechococcus lividus, which were shielded against background radiation or exposed to very low doses of gamma radiation, demonstrated that radiation can stimulate the proliferation of these two single-cell organisms. Radiation hormesis depends on internal factors (age of starting cells) and external factors (lighting conditions). The stimulatory effect occurred only in a limited range of doses and disappeared for dose rates higher than 50 mGy/y.

  2. Interactions between endothelial cells and T cells modulate responses to mixed neutron/gamma radiation.

    PubMed

    Cary, Lynnette H; Noutai, Daniel; Salber, Rudolph E; Williams, Margaret S; Ngudiankama, Barbara F; Whitnall, Mark H

    2014-06-01

    Detonation of an improvised nuclear device near a population center would cause significant casualties from the acute radiation syndrome (ARS) due to exposure to mixed neutron/gamma fields (MF). The pathophysiology of ARS involves inflammation, microvascular damage and alterations in immune function. Interactions between endothelial cells (EC) and hematopoietic cells are important not only for regulating immune cell traffic and function, but also for providing the microenvironment that controls survival, differentiation and migration of hematopoietic stem and progenitor cells in blood-forming tissues. Endothelial cells/leukocyte interactions also influence tumor progression and the results of anticancer therapies. In this study, we hypothesized that irradiation of endothelial cells would modulate their effects on hematopoietic cells and vice versa. Human umbilical vein endothelial cells (HUVEC) and immortalized T lymphocytes (Jurkat cells) were cultured individually and in co-culture after exposure to mixed fields. Effects of nonirradiated cells were compared to effects of irradiated cells and alterations in signaling pathways were determined. Mitogen-activated protein kinases (MAPKs) p38 and p44/42 (ERK1/2) in HUVEC exhibited higher levels of phosphorylated protein after exposure to mixed field radiation. IL-6, IL-8, G-CSF, platelet derived growth factor (PDGF) and angiopoietin 2 (ANG2) protein expression were upregulated in HUVEC by exposure to mixed field radiation. PCR arrays using HUVEC mRNA revealed alterations in gene expression after exposure to mixed fields and/or co-culture with Jurkat cells. The presence of HUVEC also influenced the function of Jurkat cells. Nonirradiated Jurkat cells showed an increase in proliferation when co-cultured with nonirradiated HUVEC, and a decrease in proliferation when co-cultured with irradiated HUVEC. Additionally, nonirradiated Jurkat cells incubated in media from irradiated HUVEC exhibited upregulation of activated caspase 3. Irradiation of Jurkat cells caused a G2/M arrest and increased adherence to HUVEC. When co-cultured with HUVEC, irradiated Jurkat cells exhibited G0/G1 arrest and increased apoptosis. The data indicate that gene expression and cell function of endothelial cells and hematopoietic cells are influenced by radiation and by interactions between the two cell types. These phenomena may affect the success of therapies for ARS and cancer. PMID:24828109

  3. Investigation of feasibility of using mexamine for postradiation protection of L cells. [Gamma radiation

    Microsoft Academic Search

    S. N. Valter; Yu. F. Martynchik; A. G. Sverdlov

    1977-01-01

    Suspension of L cells were exposed to gamma radiation; mexamine was added before and after irradiation. Effects of caffeine on cells were also studied. Observations were made on survival time, colony formation, and chromosomal aberrations. When mexamine was administered before irradiation a protective effect was demonstrated, but when added after irradiation there was no protective effect. Caffeine did not have

  4. Sensitivity of hyperthermia-treated human cells to killing by ultraviolet or gamma radiation

    SciTech Connect

    Mitchel, R.E.; Smith, B.P.; Wheatly, N.; Chan, A.; Child, S.; Paterson, M.C.

    1985-11-01

    Human xeroderma pigmentosum (XP) or Fanconi anemia (FA) fibroblasts displayed shouldered 45/sup 0/C heat survival curves not significantly different from normal fibroblasts, a result similar to that previously found for ataxia telangiectasia (AT) cells, indicating heat resistance is not linked to either uv or low-LET ionizing radiation resistance. Hyperthermia (45/sup 0/C) sensitized normal and XP fibroblasts to killing by gamma radiation but failed to sensitize the cells to the lethal effects of 254 nm uv radiation. Thermal inhibition of repair of ionizing radiation lesions but not uv-induced lesions appears to contribute synergistically to cell death. The thermal enhancement ratio (TER) for the synergistic interaction of hyperthermia (45/sup 0/C, 30 min) and gamma radiation was significantly lower in one FA and two strains (TER = 1.7-1.8) than that reported previously for three normal strains (TER = 2.5-3.0). These XP and FA strains may be more gamma sensitive than normal human fibroblasts. Since hyperthermia treatment only slightly increases the gamma-radiation sensitivity of ataxia telangiectasia (AT) fibroblasts compared to normal strains, it is possible that the degree of thermal enhancement attainable reflects the genetically inherent ionizing radiation repair capacity of the cells. The data indicate that both repair inhibition and particular lesion types are required for lethal synergism between heat and radiation. We therefore postulate that the transient thermal inhibition of repair results in the conversion of gamma-induced lesions to irrepairable lethal damage, while uv-type damage can remain unaltered during this period.

  5. Cell membrane oxidative damage induced by gamma-radiation and apoptotic sensitivity.

    PubMed

    Mishra, Kaushala P

    2004-01-01

    Ionizing radiation-generated reactive oxygen species (ROS) resulting in oxidative damage to the cell membrane and its consequent role in the mechanism of apoptotic cell death have been receiving growing attention in cellular radiobiology. In recent years, evidence has accumulated to suggest that it is the damage to the cell membrane that contributes to the radiation cell killing. It has been demonstrated that degradation of membrane-bound sphingomyelinase (SMase) after irradiation of bovine endothelial cell produces ceramide, which initiates an apoptotic cascade, suggesting membrane-triggered events in the mechanism of cellular apoptosis. Fluorescence and electron spin resonance (ESR) studies from gamma-irradiation ofliposomal vesicles have shown that radiation-mediated lipid damage was modified by the inclusion of structure-modulating agents (e.g., cholesterol) and antioxidants (e.g., tocopherol, eugenol). The magnitude of the modification of the damage was found to be dependent on the concentration of these modifiers. Moreover, experiments on dipalmitoyl phosphatidyl choline (DPPC) unilamellar liposomes demonstrated a biphasic behavior of radiation damage, which was remarkably modified by ascorbic acid and alpha-tocopherol in a concentration-dependent fashion. The comparison of their protective effects showed that ascorbic acid was less effective than tocopherol against radiation damage to liposomes. Studies on irradiated mouse thymocytes employing FDA fluorescence probe have suggested post-irradiation time- and dose-dependent changes in membrane permeability. The determination of induction of apoptosis in irradiated thymocytes showed a time-dependent DNA fragmentation, suggesting that radiation-induced permeability changes and occurrence of apoptotic death in thymocytes were closely correlated. These results are discussed, with an emphasis on membrane-damage-mediated apoptotic death with relevance to improvement of cancer radiotherapy. PMID:14994996

  6. Relationship between the repair of radiation-induced DNA damage and recovery from potentially lethal damage in 9L rat brain tumor cells. [Gamma radiation

    Microsoft Academic Search

    S. C. vanAnkeren; K. T. Wheeler

    1984-01-01

    The kinetics of repair of radiation-induced DNA damage and recovery from radiation-induced potentially lethal damage (PLD) for fed plateau-phase 9L\\/Ro rat brain tumor cells were compared after single doses of gamma-radiation and after combined treatment with 3 micrograms of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU)\\/ml given 16 hr prior to irradiation. DNA damage and repair were assayed using alkaline filter elution, while cell survival

  7. Chromosomal instability in unirradiated hemopoietic cells resulting from a delayed in vivo bystander effect of gamma radiation.

    PubMed

    Lorimore, Sally A; McIlrath, Joanne M; Coates, Philip J; Wright, Eric G

    2005-07-01

    Untargeted effects of ionizing radiation (de novo effects in the unirradiated descendants or neighbors of irradiated cells) challenge widely held views about the mechanisms of radiation-induced DNA damage with implications for the health consequences of radiation exposures particularly in the context of the induction of malignancy. To investigate in vivo untargeted effects of sparsely ionizing (low linear energy transfer) radiation, a congenic sex-mismatch bone marrow transplantation protocol has been used to repopulate the hemopoietic system from a mixture of gamma-irradiated and nonirradiated hemopoietic stem cells such that host-, irradiated donor- and unirradiated donor-derived cells can be distinguished. Chromosomal instability in the progeny of irradiated hemopoietic stem cells accompanied by a reduction in their contribution to the repopulated hemopoietic system is consistent with a delayed genomic instability phenotype being expressed in vivo. However, chromosomal instability was also shown in the progeny of the nonirradiated hemopoietic stem cells implicating a bystander mechanism. Studies of the influence of irradiated recipient stromal microenvironment and experiments replacing irradiated cells with irradiated cell-conditioned medium reveal the source of the in vivo bystander effect to be the descendants of irradiated cells, rather than irradiated cell themselves. Thus, it is possible that a radiation-induced genomic instability phenotype in vivo need not necessarily be a reflection of intrinsically unstable cells but the responses to ongoing production of inflammatory-type damaging signals as a long-term unexpected consequence of the initial single radiation exposure. PMID:15994940

  8. Mutant quantity and quality in mammalian cells (A{sub L}) exposed to cesium-137 gamma radiation: Effect of caffeine

    SciTech Connect

    McGuinness, S.M.; Shibuya, M.L.; Ueno, A.M. [Colorado State Univ., Fort Collins, CO (United States)] [and others

    1995-06-01

    We examined the effect of caffeine (1,3,7-trimethylxanthine) on the quantity and quality of mutations in cultured mammalian A{sub L} human-hamster hybrid cells exposed to {sup 137}Cs {gamma} radiation. At a dose (1.5 mg/ml for 16 h) that reduced the plating efficiency (PE) by 20%, caffeine was not itself a significant mutagen, but it increased by approximately twofold the slope of the dose-response curve for induction of S1{sup {minus}} mutants by {sup 137}Cs {gamma} radiation. Molecular analysis of 235 S1{sup {minus}} mutants using a series of DNA probes mapped to the human chromosome 11 in the A{sub L} hybrid cells revealed that 73 to 85% of the mutations in unexposed cells and in cells treated with caffeine alone, {sup 137}Cs {gamma} rays alone or {sup 137}Cs {gamma} rays plus caffeine were large deletions involving millions of base pairs of DNA. Most of these deletions were contiguous with the region of the MIC1 gene at 11p13 that encodes the S1 cell surface antigen. In other mutants that had suffered multiple marker loss, the deletions were intermittent along chromosome 11. These {open_quotes}complex{close_quotes} mutations were rare for {sup 137}Cs {gamma} irradiation (1/63 = 1.5%) but relatively prevalent (23-50%) for other exposure conditions. Thus caffeine appears to alter both the quantity and quality of mutations induced by {sup 137}Cs {gamma} irradiation. 62 refs., 3 figs., 3 tabs.

  9. REDD1 Protects Osteoblast Cells from Gamma Radiation-Induced Premature Senescence

    Microsoft Academic Search

    Xiang Hong Li; Cam T. Ha; Dadin Fu; Mang Xiao

    2012-01-01

    Radiotherapy is commonly used for cancer treatment. However, it often results in side effects due to radiation damage in normal tissue, such as bone marrow (BM) failure. Adult hematopoietic stem and progenitor cells (HSPC) reside in BM next to the endosteal bone surface, which is lined primarily by hematopoietic niche osteoblastic cells. Osteoblasts are relatively more radiation-resistant than HSPCs, but

  10. gamma. radiation effects on Collembola

    SciTech Connect

    Loring, S.J.

    1985-12-01

    Pitfall traps were used to collect surface-active Collembola at intervals of 10-100 m from a ..gamma.. radiation source on Long Island, N.Y., during the summer of 1968. Thirty-two species of Collembola were collected along the radiation transect. Community diversities were similar at all intervals except 10 m. Collembola appeared resistant to ..gamma.. radiation; only chronic, very high ..gamma.. radiation exposure seriously affected population levels and community diversity of surface Collembola.

  11. The Effects of Gamma and Proton Radiation Exposure on Hematopoietic Cell Counts in the Ferret Model.

    PubMed

    Sanzari, Jenine K; Wan, X Steven; Krigsfeld, Gabriel S; Wroe, Andrew J; Gridley, Daila S; Kennedy, Ann R

    2013-10-01

    Exposure to total-body radiation induces hematological changes, which can detriment one's immune response to wounds and infection. Here, the decreases in blood cell counts after acute radiation doses of ?-ray or proton radiation exposure, at the doses and dose-rates expected during a solar particle event (SPE), are reported in the ferret model system. Following the exposure to ?-ray or proton radiation, the ferret peripheral total white blood cell (WBC) and lymphocyte counts decreased whereas neutrophil count increased within 3 hours. At 48 hours after irradiation, the WBC, neutrophil, and lymphocyte counts decreased in a dose-dependent manner but were not significantly affected by the radiation type (?-rays verses protons) or dose rate (0.5 Gy/minute verses 0.5 Gy/hour). The loss of these blood cells could accompany and contribute to the physiological symptoms of the acute radiation syndrome (ARS). PMID:25356435

  12. Analysis of White Blood Cell Counts in Mice after Gamma- or Proton-Radiation Exposure

    PubMed Central

    Maks, Casey J.; Wan, X. Steven; Ware, Jeffrey H.; Romero-Weaver, Ana L.; Sanzari, Jenine K.; Wilson, Jolaine M.; Rightnar, Steve; Wroe, Andrew J.; Koss, Peter; Gridley, Daila S.; Slater, James M.; Kennedy, Ann R.

    2013-01-01

    In the coming decades human space exploration is expected to move beyond low-Earth orbit. This transition involves increasing mission time and therefore an increased risk of radiation exposure from solar particle event (SPE) radiation. Acute radiation effects after exposure to SPE radiation are of prime importance due to potential mission-threatening consequences. The major objective of this study was to characterize the dose–response relationship for proton and ? radiation delivered at doses up to 2 Gy at high (0.5 Gy/min) and low (0.5 Gy/h) dose rates using white blood cell (WBC) counts as a biological end point. The results demonstrate a dose-dependent decrease in WBC counts in mice exposed to high- and low-dose-rate proton and ? radiation, suggesting that astronauts exposed to SPE-like radiation may experience a significant decrease in circulating leukocytes. PMID:21476859

  13. Indoleamine 2,3-dioxygenase mediates immune-independent human tumor cell resistance to olaparib, gamma radiation, and cisplatin.

    PubMed

    Maleki Vareki, Saman; Rytelewski, Mateusz; Figueredo, Rene; Chen, Di; Ferguson, Peter J; Vincent, Mark; Min, Weiping; Zheng, Xiufen; Koropatnick, James

    2014-05-15

    Indoleamine 2,3-dioxygenase-1 (IDO) is an immunosuppressive molecule expressed by most human tumors. IDO levels correlate with poor prognosis in cancer patients and IDO inhibitors are under investigation to enhance endogenous anticancer immunosurveillance. Little is known of immune-independent functions of IDO relevant to cancer therapy. We show, for the first time, that IDO mediates human tumor cell resistance to a PARP inhibitor (olaparib), gamma radiation, cisplatin, and combined treatment with olaparib and radiation, in the absence of immune cells. Antisense-mediated reduction of IDO, alone and (in a synthetic lethal approach) in combination with antisense to the DNA repair protein BRCA2 sensitizes human lung cancer cells to olaparib and cisplatin. Antisense reduction of IDO decreased NAD+ in human tumor cells. NAD+ is essential for PARP activity and these data suggest that IDO mediates treatment resistance independent of immunity and at least partially due to a previously unrecognized role for IDO in DNA repair. Furthermore, IDO levels correlated with accumulation of tumor cells in G1 and depletion of cells in G2/M of the cell cycle, suggesting that IDO effects on cell cycle may also modulate sensitivity to radiation and chemotherapeutic agents. IDO is a potentially valuable therapeutic target in cancer treatment, independent of immune function and in combination with other therapies. PMID:24784564

  14. Indoleamine 2,3-dioxygenase mediates immune-independent human tumor cell resistance to olaparib, gamma radiation, and cisplatin

    PubMed Central

    Vareki, Saman Maleki; Rytelewski, Mateusz; Figueredo, Rene; Chen, Di; Ferguson, Peter J.; Vincent, Mark; Min, Weiping; Zheng, Xiufen; Koropatnick, James

    2014-01-01

    Indoleamine 2,3-dioxygenase-1 (IDO) is an immunosuppressive molecule expressed by most human tumors. IDO levels correlate with poor prognosis in cancer patients and IDO inhibitors are under investigation to enhance endogenous anticancer immunosurveillance. Little is known of immune-independent functions of IDO relevant to cancer therapy. We show, for the first time, that IDO mediates human tumor cell resistance to a PARP inhibitor (olaparib), gamma radiation, cisplatin, and combined treatment with olaparib and radiation, in the absence of immune cells. Antisense-mediated reduction of IDO, alone and (in a synthetic lethal approach) in combination with antisense to the DNA repair protein BRCA2 sensitizes human lung cancer cells to olaparib and cisplatin. Antisense reduction of IDO decreased NAD+ in human tumor cells. NAD+ is essential for PARP activity and these data suggest that IDO mediates treatment resistance independent of immunity and at least partially due to a previously unrecognized role for IDO in DNA repair. Furthermore, IDO levels correlated with accumulation of tumor cells in G1 and depletion of cells in G2/M of the cell cycle, suggesting that IDO effects on cell cycle may also modulate sensitivity to radiation and chemotherapeutic agents. IDO is a potentially valuable therapeutic target in cancer treatment, independent of immune function and in combination with other therapies. PMID:24784564

  15. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H. (Knoxville, TN)

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  16. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  17. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H. (Knoxville, TN)

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  18. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  19. Enhanced killing of irradiated HeLa cells in synchronous culture by hyperthermia. [Gamma radiation

    Microsoft Academic Search

    S. H. Kim; J. H. Kim; E. W. Hahn

    1976-01-01

    Mitotically synchronized cultures of HeLa S-3 cells were subjected to the treatment of radiation (400 rad), hyperthermia (43°C), and a combination of both at different phases of the division cycle. The radioresistance was most pronounced in the mid G-1 and late S phases, while thermal resistance was greatest in the early G-1 phase and steadily decreased as cells entered the

  20. Increase of RhoB in {gamma}-radiation-induced apoptosis is regulated by c-Jun N-terminal kinase in Jurkat T cells

    SciTech Connect

    Kim, Chun-Ho [Laboratory of Cytogenetics and Tissue Regeneration, KIRAMS, Seoul 139-706 (Korea, Republic of)] [Laboratory of Cytogenetics and Tissue Regeneration, KIRAMS, Seoul 139-706 (Korea, Republic of); Won, Misun; Choi, Chung-Hae; Ahn, Jiwon; Kim, Bo-Kyung [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of)] [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of); Song, Kyung-Bin [Department of Food Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)] [Department of Food Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kang, Chang-Mo, E-mail: kangcm@kcch.re.kr [Laboratory of Cytogenetics and Tissue Regeneration, KIRAMS, Seoul 139-706 (Korea, Republic of)] [Laboratory of Cytogenetics and Tissue Regeneration, KIRAMS, Seoul 139-706 (Korea, Republic of); Chung, Kyung-Sook, E-mail: kschung@kribb.re.kr [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of)] [Genome Research Center, KRIBB, Daejeon 305-806 (Korea, Republic of)

    2010-01-08

    The Ras-related small GTP-binding protein RhoB is known to be a pro-apoptotic protein and immediate-early inducible by genotoxic stresses. In addition, JNK activation is known to function in {gamma}-radiation-induced apoptosis. However, it is unclear how JNK activation and {gamma}-radiation-dependent RhoB induction are related. Here we verified the relationship between JNK activation and RhoB induction. RhoB induction by {gamma}-radiation occurred at the transcriptional level and transcriptional activation of RhoB was concomitant with an increase in RhoB protein. {gamma}-Radiation-induced RhoB expression was markedly attenuated by pretreatment with a JNK-specific inhibitor, SP600125, but not by a p38 MAPK inhibitor, SB203580. Inhibition of JNK caused a decrease in early apoptotic cell death that correlated with RhoB expression. However, PI3K inhibition had no significant effects, indicating that the AKT survival pathway was not involved. The siRNA knockdown of JNK resulted in a decrease in RhoB expression and the siRNA knockdown of RhoB restored cell growth even in the {gamma}-irradiated cells. These results suggest that RhoB regulation involves the JNK pathway and contributes to the early apoptotic response of Jurkat T cells to {gamma}-radiation.

  1. Abdominal {gamma}-Radiation Induces an Accumulation of Function-Impaired Regulatory T Cells in the Small Intestine

    SciTech Connect

    Billiard, Fabienne; Buard, Valerie; Benderitter, Marc [Institut de Radioprotection et de Surete Nucleaire, Direction de la Radioprotection de l'Homme, B.P. no. 17, Fontenay-aux-Roses (France); Linard, Christine, E-mail: christine.linard@irsn.fr [Institut de Radioprotection et de Surete Nucleaire, Direction de la Radioprotection de l'Homme, B.P. no. 17, Fontenay-aux-Roses (France)

    2011-07-01

    Purpose: To assess the frequency and the functional characteristics of one major component of immune tolerance, the CD4{sup +}FoxP3{sup +} regulatory T cells (Tregs) in a mouse model of abdominal irradiation. Methods and Materials: Mice were exposed to a single abdominal dose of {gamma}-radiation (10 Gy). We evaluated small intestine Treg infiltration by Foxp3 immunostaining and the functional suppressive activity of Tregs isolated from mesenteric lymph nodes. Results: Foxp3 immunostaining showed that radiation induced a long-term infiltration of the intestine by Tregs (levels 5.5 times greater than in controls). Co-culture of Tregs from mesenteric lymph nodes with CD4{sup +} effector cells showed that the Tregs had lost their suppressive function. This loss was associated with a significant decrease in the levels of Foxp3, TGF-{beta}, and CTLA-4 mRNA, all required for optimal Treg function. At Day 90 after irradiation, Tregs regained their suppressive activity as forkhead box P3 (Foxp3), transforming growth factor beta (TGF-{beta}), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) expression returned to normal. Analysis of the secretory function of mesenteric lymph node Tregs, activated in vitro with anti-CD3/anti-CD28 Abs, showed that this dysfunction was independent of a defect in interleukin-10 secretion. Conclusion: Radiation caused a long-term accumulation of function-impaired Foxp3{sup +}CD4{sup +} Tregs in the intestine. Our study provides new insights into how radiation affects the immune tolerance in peripheral tissues.

  2. Combination of PTEN and {gamma}-Ionizing Radiation Enhances Cell Death and G{sub 2}/M Arrest Through Regulation of AKT Activity and p21 Induction in Non-Small-Cell Lung Cancer Cells

    SciTech Connect

    Park, Jong Kuk; Jung, Hae-Yun; Park, Seon Ho; Kang, Seung Yi; Yi, Mi-Rang; Um, Hong Duck [Laboratory of Radiation Tumor Physiology, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Hong, Sung Hee [Laboratory of Radiation Tumor Physiology, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)], E-mail: gobrian@kcch.re.kr

    2008-04-01

    Purpose: To identify the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) during {gamma}-ionizing radiation ({gamma}-IR) treatment for non-small-cell lung cancer cells. Methods and Materials: Wild-type PTEN or mutant forms of PTEN plasmids were transfected to construct stable transfectants of the NCI-H1299 non-small-cell lung cancer cell line. Combined effects of PTEN expression and IR treatment were tested using immunoblot, clonogenic, and cell-counting assays. Related signaling pathways were studied with immunoblot and kinase assays. Results: At steady state, stable transfectants showed almost the same proliferation rate but had different AKT phosphorylation patterns. When treated with {gamma}-IR, wild-type PTEN transfectants showed higher levels of cell death compared with mock vector or mutant transfectants, and showed increased G{sub 2}/M cell-cycle arrest accompanied by p21 induction and CDK1 inactivation. NCI-H1299 cells were treated with phosphosinositide-3 kinase (PI3K)/AKT pathway inhibitor (LY29002), resulting in reduced AKT phosphorylation levels. Treatment of NCI-H1299 cells with LY29002 and {gamma}-IR resulted in increased cell-cycle arrest and p21 induction. Endogenous wild-type PTEN-containing NCI-H460 cells were treated with PTEN-specific siRNA and then irradiated with {gamma}-IR: however reduced PTEN levels did not induce cell-cycle arrest or p21 expression. Conclusions: Taken together, these findings indicate that PTEN may modulate cell death or the cell cycle via AKT inactivation by PTEN and {gamma}-IR treatment. We also propose that a PTEN-PI3K/AKT-p21-CDK1 pathway could regulate cell death and the cell cycle by {gamma}-IR treatment.

  3. Comparative investigations of sodium arsenite, arsenic trioxide and cadmium sulphate in combination with gamma-radiation on apoptosis, micronuclei induction and DNA damage in a human lymphoblastoid cell line

    Microsoft Academic Search

    Sabine Hornhardt; Maria Gomolka; Linda Walsh; Thomas Jung

    2006-01-01

    In the field of radiation protection the combined exposure to radiation and other toxic agents is recognised as an important research area. To elucidate the basic mechanisms of simultaneous exposure, the interaction of the carcinogens and environmental toxicants cadmium and two arsenic compounds, arsenite and arsenic trioxide, in combination with gamma-radiation in human lymphoblastoid cells (TK6) were investigated. Gamma-radiation induced

  4. Gamma radiation characteristics of plutonium dioxide fuel

    NASA Technical Reports Server (NTRS)

    Gingo, P. J.

    1969-01-01

    Investigation of plutonium dioxide as an isotopic fuel for Radioisotope Thermoelectric Generators yielded the isotopic composition of production-grade plutonium dioxide fuel, sources of gamma radiation produced by plutonium isotopes, and the gamma flux at the surface.

  5. Enhanced radiation-induced cell killing and prolongation of gammaH2AX foci expression by the histone deacetylase inhibitor MS-275.

    PubMed

    Camphausen, Kevin; Burgan, William; Cerra, Michael; Oswald, Kelli A; Trepel, Jane B; Lee, Min-Jung; Tofilon, Philip J

    2004-01-01

    Histone deacetylase (HDAC) inhibitors are undergoing clinical evaluation for cancer therapy. Because HDAC modulates chromatin structure and gene expression, parameters considered to influence radioresponse, we have investigated the effects of the HDAC inhibitor MS-275 on the radiosensitivity of two human tumor cell lines (DU145 prostate carcinoma and U251 glioma). Acetylation status of histones H3 and H4 was determined as a function of time after MS-275 addition to and removal from culture medium. Histone acetylation increased by 6 h after MS-275 addition, reaching a maximum between 24 and 48 h of exposure; providing fresh drug-free medium then resulted in a decrease in histone acetylation that began by 6 h and approached untreated levels by 16 h. Treatment of cells with MS-275 for 48 h followed by irradiation had little or no effect on radiation-induced cell death. However, exposure to MS-275 before and after irradiation resulted in an increase in radiosensitivity with dose enhancement factors of 1.9 and 1.3 for DU145 and U251 cells, respectively. This MS-275 treatment protocol did not result in a redistribution of the cells into a more radiosensitive phase of the cell cycle or in an increase in apoptosis. However, MS-275 did modify the time course of gammaH2AX expression in irradiated cells. Whereas there was no significant difference in radiation-induced gammaH2AX foci at 6 h, the number of cells expressing gammaH2AX foci was significantly greater in the MS-275-treated cells at 24 h after irradiation. These results indicate that MS-275 can enhance radiosensitivity and suggest that this effect may involve an inhibition of DNA repair. PMID:14729640

  6. Protective Role of Hsp27 Protein Against Gamma Radiation-Induced Apoptosis and Radiosensitization Effects of Hsp27 Gene Silencing in Different Human Tumor Cells

    SciTech Connect

    Aloy, Marie-Therese [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France); Hospices Civils de Lyon, Service de Radiotherapie, Centre Hospitalier Lyon-Sud, Pierre-Benite (France)], E-mail: marie-therese.aloy@sante.univ-lyon1.fr; Hadchity, Elie; Bionda, Clara [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France); Diaz-Latoud, Chantal [Universite de Lyon 1, UMR-CNRS-5534, Centre de Genetique Moleculaire et Cellulaire, Villeurbanne (France); Claude, Line; Rousson, Robert [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France); Arrigo, Andre-Patrick [Universite de Lyon 1, UMR-CNRS-5534, Centre de Genetique Moleculaire et Cellulaire, Villeurbanne (France); Rodriguez-Lafrasse, Claire [Universite de Lyon 1, Laboratoire de Radiobiologie Cellulaire et Moleculaire, Faculte de Medecine Lyon-Sud, Oullins (France)

    2008-02-01

    Purpose: The ability of heat shock protein 27 (Hsp27) to protect cells from stressful stimuli and its increased levels in tumors resistant to anticancer therapeutics suggest that it may represent a target for sensitization to radiotherapy. In this study, we investigate the protective role of Hsp27 against radiation-induced apoptosis and the effect of its attenuation in highly expressing radioresistant cancer cell lines. Methods and Materials: We examined clonogenic death and the kinetics of apoptotic events in different tumor cell lines overexpressing or underexpressing Hsp27 protein irradiated with photons. The radiosensitive Jurkat cell line, which does not express Hsp27 constitutively or in response to {gamma}-rays, was stably transfected with Hsp27 complementary DNA. Attenuation of Hsp27 expression was accomplished by antisense or RNAi (interfering RNA) strategies in SQ20B head-and-neck squamous carcinoma, PC3 prostate cancer, and U87 glioblastoma radioresistant cells. Results: We measured concentration-dependent protection against the cytotoxic effects of radiation in Jurkat-Hsp27 cells, which led to a 50% decrease in apoptotic cells at 48 hours in the highest expressing cells. Underlying mechanisms leading to radiation resistance involved a significant increase in glutathione levels associated with detoxification of reactive oxygen species, a delay in mitochondrial collapse, and caspase activation. Conversely, attenuation of Hsp27 in SQ20B cells, characterized by their resistance to apoptosis, sensitizes cells to irradiation. This was emphasized by increased apoptosis, decreased glutathione basal level, and clonogenic cell death. Sensitization to irradiation was confirmed in PC3 and U87 radioresistant cells. Conclusion: Hsp27 gene therapy offers a potential adjuvant to radiation-based therapy of resistant tumors.

  7. Antagonistic effects of black tea against gamma radiation-induced oxidative damage to normal lymphocytes in comparison with cancerous K562 cells.

    PubMed

    Ghosh, Debjani; Dey, Subrata Kumar; Saha, Chabita

    2014-11-01

    The potential of naturally occurring antioxidants to reduce the cellular oxidative damage induced by ionizing radiation has been studied for more than a decade for their pharmacological application during cancer treatment. It is already known that radioprotective efficacy of phytochemicals might influence various end points of radiation damage. Flavonoids are well-known natural radioprotectors, and their biological effects depend upon their chemical structure. In the present study, radioprotective effect of black tea rich in flavonoids was evaluated against gamma radiation-induced oxidative damage on normal lymphocytes and compared with erythroleukemic K562 cells. Pre-treatment with black tea extract (BTE) significantly reduced radiation-induced loss of cell viability, generation of reactive oxygen species, mitochondrial dysfunction, activation of caspase-3 and apoptosis in normal lymphocytes compared to K562 cells. BTE also regulates the activity of endogenous antioxidant enzymes. The changes in the mRNA expression of bax, bcl2, p53 and Nrf2 were also followed to evaluate regulation of radiation-induced apoptosis by BTE. These findings suggest that black tea may have the potential of a natural radioprotective agent which can be used as adjunct with radiation during cancer treatment. PMID:24981250

  8. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    SciTech Connect

    Scott Wilde, Raymond Keegan

    2008-07-01

    The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

  9. Gamma radiation exposure of MCT diode arrays

    Microsoft Academic Search

    F. F. Sizov; I. O. Lysiuk; J. V. Gumenjuk-Sichevska; S. G. Bunchuk; V. V. Zabudsky

    2006-01-01

    Investigations of electrical properties of long-wavelength infrared (LWIR) mercury cadmium telluride arrays exposed to gamma-radiation have been performed. Resistance-area product characteristics of LWIR n+-p-photodiodes have been investigated using a microprobe technique at T ap 78 K before and after exposure to various doses of gamma-radiation (Co60 Gammas). The current transport mechanisms for those structures are described within the framework of

  10. Cell engineering: nanometric grafting of poly-N-isopropylacrylamide onto polystyrene film by different doses of gamma radiation

    PubMed Central

    Biazar, Esmaeil; Zeinali, Reza; Montazeri, Naser; Pourshamsian, Khalil; Behrouz, Mahmoud Jabarvand; Asefnejad, Azadeh; Khoshzaban, Ahad; Shahhosseini, Gholamreza; Najafabadi, Mostafa Soleimannejad; Abyani, Reza; Jamalzadeh, Hamidreza; Fouladi, Mahdi; Hagh, Sasan Rahbar F; Khamaneh, Aylar Shams; Kabiri, Soudabeh; Keshel, Saeed Heidari; Mansourkiaei, Ana

    2010-01-01

    Poly-N-isopropylacrylamide was successfully grafted onto a polystyrene cell culture dish and ?-preirradiated in air. In this study, the effect of a ?-pre-irradiation dose of radiation (radiation absorbed dosages of 10, 20, 30, 40 KGy) under appropriate temperature and grafting conditions was investigated. The Fourier transform infrared spectroscopy analysis showed the existence of the graft poly-N-isopropylacrylamide (PNIPAAm) on the substrate. The optimal value of the dose for grafting was 40 KGy at 50°C. The scanning electron microscopy and atomic force microscopy (AFM) images clearly showed that increasing the absorbed dose of radiation would increase the amount of grafting. Surface topography and graft thickness in AFM images of the radiated samples showed that the PNIPAAm at the absorbed dose of radiation was properly grafted. The thickness of these grafts was about 50–100 nm. The drop water contact angles of the best grafted sample at 37°C and 10°C were 55.3 ± 1.2° and 61.2 ± 0.9° respectively, which showed the hydrophilicity and hydrophobicity of the grafted surfaces. Differential scanning calorimetry analysis also revealed the low critical solution temperature of the grafted sample to be 32°C. Thermoresponsive polymers were grafted to dishes covalently which allowed fibroblast cells to attach and proliferate at 37°C; the cells also detached spontaneously without using enzymes when the temperature dropped below 32°C. This characteristic proves that this type of grafted material has potential as a biomaterial for cell sheet engineering. PMID:20957116

  11. Do the various radiations present in BNCT act synergistically? Cell survival experiments in mixed alpha-particle and gamma-ray fields.

    PubMed

    Phoenix, Ben; Green, Stuart; Hill, Mark A; Jones, Bleddyn; Mill, Andrew; Stevens, David L

    2009-07-01

    In many radiotherapy situations patients are exposed to mixed field radiation. In particular in BNCT, as with all neutron beam exposures, a significant fraction of the dose is contributed by low LET gamma ray photons. The components of such a mixed field may show a synergistic interaction and produce a greater cell kill effect than would be anticipated from the independent action of the different radiation types. Such a synergy would have important implications for treatment planning and in the interpretation of clinical results. An irradiation setup has been created at the Medical Research Council in Harwell to allow simultaneous irradiation of cells by cobalt-60 gamma rays and plutonium-238 alpha-particles. The setup allows for variation of dose and dose rates for both sources along with variation of the alpha particle energy. A series of cell survival assays for this mixed field have been carried out using V79-4 cells and compared to exposures to the individual components of the field under identical conditions. In the experimental setup described no significant synergistic effect was observed. PMID:19376715

  12. Low Dose Radiation Response Curves, Networks and Pathways in Human Lymphoblastoid Cells Exposed from 1 to 10 cGy of Acute Gamma Radiation

    SciTech Connect

    Wyrobek, A. J.; Manohar, C. F.; Nelson, D. O.; Furtado, M. R.; Bhattacharya, M. S.; Marchetti, F.; Coleman, M.A.

    2011-04-18

    We investigated the low dose dependency of the transcriptional response of human cells to characterize the shape and biological functions associated with the dose response curve and to identify common and conserved functions of low dose expressed genes across cells and tissues. Human lymphoblastoid (HL) cells from two unrelated individuals were exposed to graded doses of radiation spanning the range of 1-10 cGy were analyzed by transcriptome profiling, qPCR and bioinformatics, in comparison to sham irradiated samples. A set of {approx}80 genes showed consistent responses in both cell lines; these genes were associated with homeostasis mechanisms (e.g., membrane signaling, molecule transport), subcellular locations (e.g., Golgi, and endoplasmic reticulum), and involved diverse signal transduction pathways. The majority of radiation-modulated genes had plateau-like responses across 1-10 cGy, some with suggestive evidence that transcription was modulated at doses below 1 cGy. MYC, FOS and TP53 were the major network nodes of the low-dose response in HL cells. Comparison our low dose expression findings in HL cells with those of prior studies in mouse brain after whole body exposure, in human keratinocyte cultures, and in endothelial cells cultures, indicates that certain components of the low dose radiation response are broadly conserved across cell types and tissues, independent of proliferation status.

  13. Apparatus and method for detecting gamma radiation

    DOEpatents

    Sigg, R.A.

    1994-12-13

    A high efficiency radiation detector is disclosed for measuring X-ray and gamma radiation from small-volume, low-activity liquid samples with an overall uncertainty better than 0.7% (one sigma SD). The radiation detector includes a hyperpure germanium well detector, a collimator, and a reference source. The well detector monitors gamma radiation emitted by the reference source and a radioactive isotope or isotopes in a sample source. The radiation from the reference source is collimated to avoid attenuation of reference source gamma radiation by the sample. Signals from the well detector are processed and stored, and the stored data is analyzed to determine the radioactive isotope(s) content of the sample. Minor self-attenuation corrections are calculated from chemical composition data. 4 figures.

  14. Centromere detection in vinblastine- and radiation-induced micronuclei of cytokinesis-blocked mouse cells by using in situ hybridization with a mouse gamma (major) satellite DNA probe

    SciTech Connect

    Salassidis, K.; Huber, R.; Zitzelsberger, H.; Bauchinger, M. (Inst. fuer Strahlenbiologie, Neuherberg (West Germany))

    1992-01-01

    Non-isotopic in situ hybridization using a mouse gamma (major) satellite probe DNA was applied to detect centromeres in micronuclei, which were induced in vitro mouse liver cells by ionizing radiation and by vinblastine sulfate. In a cytokinesis-blocked micronucleus assay a dose-dependent induction of micronuclei was found for both agents. After vinblastine exposure the observed micronuclei showed centromere-positive hybridization signals in an order of magnitude of 70-91%, but after radiation exposure the magnitude was only 10-20%. Since the in situ hybridization technique detects centromeric DNA directly, it can be used in a cytokinesis-blocked micronucleus assay for a rapid and reliable discrimination between aneuploidy-inducing and clastogenic agents.

  15. Relationships between DNA damage and the survival of radiosensitive mutant Chinese hamster cell lines exposed to gamma-radiation: Part 2. Effect of cellular redox status.

    PubMed

    Murray, D; Prager, A; Meyn, R E; Davison, S; Green, A D

    1993-02-01

    To characterize further the nature of the defects underlying the differential radiosensitivities of the Chinese hamster ovary cell lines NM2, EM9, and UV41, we compared the abilities of anoxia and of the thiol WR-1065 to protect these mutants and their parent cell line, AA8, from the lethal effects of gamma-radiation. Wide differences in oxygen enhancement ratios (OERs) for cell killing were observed in the different cell lines, those for UV41 and NM2 cells (1.8 and 2.1, respectively) being reduced and that for EM9 cells (3.3) being slightly (although significantly) increased compared with wild-type AA8 cells (2.9). These OER data support the hypothesis that repair-deficient mutants are hypersensitive to radiation under redox conditions that favour the formation of the particular lesions that correspond to their repair defect, and also support the earlier suggestion that the underlying molecular bases of the radiosensitivity of EM9 and NM2 cells are very different. In contrast to protection by anoxia, a 30-min preirradiation treatment with WR-1065 (4 mmol dm-3) protected aerated AA8, EM9, NM2, and UV41 cells to a similar extent with respect to both cell killing and the efficiency of DNA double-strand break (dsb) induction as measured by neutral elution. This observation is in marked contrast with reports of a greatly reduced protection by thiols for some repair-deficient cell lines and with the above-mentioned anoxia data. Thus, the particular types of mutations characteristic of NM2, EM9, and UV41 cells that give rise to their unusual OERs have little impact on the ability of WR-1065 to modify either cell killing or dsb induction, supporting radiochemical evidence that the types of deoxyribose radicals modifiable by oxygen and thiols are qualitatively different. Furthermore, because the extent of protection of these CHO mutants by thiols and anoxia show no correlation, oxygen depletion cannot be a major component of protection of aerated cells by thiols under these conditions. PMID:8094416

  16. Phenotypic and functional changes induced in hematopoietic stem/progenitor cells after gamma-ray radiation exposure.

    PubMed

    Simonnet, Arthur J; Nehmé, Johnny; Vaigot, Pierre; Barroca, Vilma; Leboulch, Philippe; Tronik-Le Roux, Diana

    2009-06-01

    Ionizing radiation (IR) exposure causes rapid and acute bone marrow (BM) suppression that is reversible for nonlethal doses. Evidence is accumulating that IR can also provoke long-lasting residual hematopoietic injury. To better understand these effects, we analyzed phenotypic and functional changes in the stem/progenitor compartment of irradiated mice over a 10-week period. We found that hematopoietic stem cells (HSCs) identified by their repopulating ability continued to segregate within the Hoechst dye excluding "side population (SP)" early after IR exposure. However, transient phenotypic changes were observed within this cell population: Sca-1 (S) and c-Kit (K) expression levels were increased and severely reduced, respectively, with a concurrent increase in the proportion of SP(SK) cells positive for established indicators of the presence of HSCs: CD150 and CD105. Ten weeks after IR exposure, expression of Sca-1 and c-Kit at the SP cell surface returned to control levels, and BM cellularity of irradiated mice was restored. However, the c-Kit(+)Sca-1(+)Lin(-/low) (KSL) stem/progenitor compartment displayed major phenotypic modifications, including an increase and a severe decrease in the frequencies of CD150(+)Flk2(-) and CD150(-)Flk2(+) cells, respectively. CD150(+) KSL cells also showed impaired reconstituting ability, an increased tendency to apoptosis, and accrued DNA damage. Finally, 15 weeks after exposure, irradiated mice, but not age-matched controls, allowed engraftment and significant hematopoietic contribution from transplanted congenic HSCs without additional host conditioning. These results provide novel insight in our understanding of immediate and delayed IR-induced hematopoietic injury and highlight similarities between HSCs of young irradiated and old mice. PMID:19489102

  17. Effects of low-dose gamma radiation on DNA damage, chromosomal aberration and expression of repair genes in human blood cells

    Microsoft Academic Search

    Wanwisa Sudprasert; Panida Navasumrit; Mathuros Ruchirawat

    2006-01-01

    Exposure to low-dose gamma radiation is common in certain occupations but the biological and health effects from such exposure remain to be determined. The aim of this study was to investigate the effects of low-dose gamma radiation on DNA damage, chromosomal aberration and DNA repair gene expressions in whole blood and peripheral lymphocytes. The study revealed a dose-dependent effect of

  18. High range gamma radiation meter

    SciTech Connect

    Baird, W.; Bjarke, D.; Eisen, Y.

    1986-02-01

    A low power meter has been constructed and tested to measure gamma fields from .1 R/h to 1500 R/h over the energy range of 60 keV to 1.2 MeV. The portable, battery-powered meter consists of a local display unit and remote probe. The display unit indicates gamma intensities via a 4-1/2 digit liquid crystal display (LCD) and a 50-segment bargraph LCD.

  19. High range gamma radiation meter

    SciTech Connect

    Baird, W.; Bjarke, G.O.; Eisen, Y.

    1985-01-01

    A low power meter has been constructed and tested to measure gamma fields from .1 R/hr to 1500 R/hr over the energy range of 60 keV to 1.2 MeV. The portable, battery-powered meter consists of a local display unit and remote probe. The display unit indicates gamma intensities via a 4-1/2 digit liquid crystal display (LCD) and a 50-segment bargraph LCD.

  20. Satellite observation of atmospheric nuclear gamma radiation

    Microsoft Academic Search

    John R. Letaw; G. H. Share; R. L. Kinzer; R. Silberberg; E. L. Chupp; D. J. Forrest; E. Rieger

    1989-01-01

    The authors present a satellite observation of the spectrum of gamma radiation from the Earth's atmosphere in the energy interval from 300 keV to 8.5 MeV. The data were accumulated by the gamma ray spectrometer on the Solar Maximum Mission over 3 1\\/2 years, from 1980 to 1983. The excellent statistical accuracy of the data allows 20 atmospheric line features

  1. Gamma radiation background measurements from Spacelab 2

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Gregory, John C.; Fishman, Gerald J.

    1989-01-01

    A Nuclear Radiation Monitor incorporating a NaI(Tl) scintillation detector was flown as part of the verification flight instrumentation on the Spacelab 2 mission, July 29 to August 6, 1985. Gamma-ray spectra were measured with better than 20 s resolution throughout most of the mission in the energy range 0.1 to 30 MeV. Knowledge of the decay characteristics and the geomagnetic dependence of the counting rates enable measurement of the various components of the Spacelab gamma-ray background: prompt secondary radiation, earth albedo, and delayed induced radioactivity. The status of the data analysis and present relevant examples of typical background behavior are covered.

  2. Gamma radiation background measurements from Spacelab 2

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Gregory, John C.; Fishman, Gerald J.

    1988-01-01

    A Nuclear Radiation Monitor incorporating a NaI(Tl) scintillation detector was flown as part of the verification flight instrumentation on the Spacelab 2 mission, July 29 to August 6, 1985. Gamma-ray spectra were measured with better than 20 s resolution throughout most of the mission in the energy range 0.1 to 30 MeV. Knowledge of the decay characteristics and the geomagnetic dependence of the counting rates enable measurement of the various components of the Spacelab gamma-ray background: prompt secondary radiation, Earth albedo, and delayed induced radioactivity. The status of the data analysis and present relevant examples of typical background behavior are covered.

  3. Cell Radiation Experiment System

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R.

    2010-01-01

    The cell radiation experiment system (CRES) is a perfused-cell culture apparatus, within which cells from humans or other animals can (1) be maintained in homeostasis while (2) being exposed to ionizing radiation during controlled intervals and (3) being monitored to determine the effects of radiation and the repair of radiation damage. The CRES can be used, for example, to determine effects of drug, radiation, and combined drug and radiation treatments on both normal and tumor cells. The CRES can also be used to analyze the effects of radiosensitive or radioprotectant drugs on cells subjected to radiation. The knowledge gained by use of the CRES is expected to contribute to the development of better cancer treatments and of better protection for astronauts, medical-equipment operators, and nuclear-power-plant workers, and others exposed frequently to ionizing radiation.

  4. Gamma ray emission from radiative supernova remnants

    NASA Astrophysics Data System (ADS)

    Asvarov, Abdul

    In this presentation we have considered Gamma-ray emission from supernova remnants (SNRs) evolving in high density environments, for which the radiative phase of evolution is more typical. Gamma-rays from such objects are believed to have hadronic origin, i.e. as a result of decay of neutral pi-mesons, created in the p-p collisions of relativistic hadrons (protons, etc.) with interstellar medium protons. DSA mechanism is considered as the main mechanism of acceleration of relativistic particles. We assume that SNR evolves in more or less homogeneous interstellar medium. This is contrary to two main models of origin of Gamma-rays from shell type SNRs, which are: 1) Runaway CR model which considers Gamma-ray emission from molecular clouds illuminated by runaway CRs that have escaped from the SNRs; 2) Crushed Cloud model, which considers the shocked interstellar clouds being responsible for the gamma-ray emission of the SNR. The considered model gives the largest conversion rate of SN energy to gamma-rays. It has been found that under certain (close to real) conditions considered here type of SNRs can easily provide the flux of gamma-rays with energies > 100 MeV, typical for the large number of unidentified sources listed in the recent Fermi LAT source catalog. We have obtained conditions under which SNRs are better observable in gamma-rays than in other bands of the electromagnetic spectrum.

  5. Gamma Radiation Doses In Sweden

    SciTech Connect

    Almgren, Sara; Isaksson, Mats [Department of Radiation Physics, Goeteborg University, Sahlgrenska University Hospital, SE-413 45 Goeteborg (Sweden); Barregaard, Lars [Department of Occupational and Environmental Medicine, Sahlgrenska Hospital and Academy, SE-405 30 Goeteborg (Sweden)

    2008-08-07

    Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096{+-}0.019(1 SD) and 0.092{+-}0.016(1 SD){mu}Sv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11{+-}0.042(1 SD) and 0.091{+-}0.026(1 SD){mu}Sv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, {sup 222}Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

  6. Radiolysis of sulfoxides. [Gamma radiation

    Microsoft Academic Search

    V. N. Korobeinikova; G. G. Bikbaeva; Yu. I. Murinov; Yu. E. Nikitin; V. P. Kazadov

    2009-01-01

    A study was made on the extractability of petroleum sulfoxides (PSO) and their closest analog tetramethylene sulfoxide (TMSO) upon ..gamma.. irradiation. A two-phase system was used, one phase being either neat PSO or diluted with twice its amount of o-xylene and the other an aqueous solution of UOâ(NOâ)â in 0.1 M HNOâ, with a 1:1 ratio by volume of the

  7. Gamma radiation effects on peanut skin antioxidants.

    PubMed

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D'Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts' antioxidative properties when added to soybean oil. PMID:22489142

  8. Gamma Radiation Effects on Peanut Skin Antioxidants

    PubMed Central

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D’Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts’ antioxidative properties when added to soybean oil. PMID:22489142

  9. Inspection of cargo containers using gamma radiation

    NASA Astrophysics Data System (ADS)

    Hussein, Esam M. A.; Gokhale, Prasad; Arendtsz, Nina V.; Lawrence, Andre H.

    1997-02-01

    This paper investigate, with the aid of Monte Carlo simulations and laboratory experiments, a technique for the detection of narcotics in large cargo containers using gamma-radiation. The transmission and back-scattering of photons, at different energies, is used to provide information useful for identifying the presence of bulk quantities of commonly encountered narcotics.

  10. Reduced temperature (22{degrees}C) results in enhancement of cell killing and neoplastic transformation in noncycling HeLa x skin fibroblast human hybrid cells irradiated with low-dose-rate gamma radiation

    SciTech Connect

    Redpath, J.L.; Antoniono, R.J. [Univ. of California, Irvine, CA (United States)

    1995-10-01

    The effect of reduced temperature (22{degrees}C) or serum deprivation during low-dose-rate (0.66 cGy/min) {gamma} irradiation on cell killing and neoplastic transformation has been examined using the HeLa x skin fibroblast human hybrid cell system. The reduced temperature stops progression of these cells through the cell cycle while serum deprivation slows down cell turnover markedly. The data demonstrate an enhancement in both of the end points when cells are held at 22{degrees}C compared to parallel experiments done at 37{degrees}C. In operational terms, the decreased survival and increased neoplastic transformation are consistent with our earlier hypothesis of a higher probability of misrepair at reduced temperature. The interpretation that this damage enhancement was associated with the reduced temperature, and not the fact that the cells were noncycling, was supported by the results of experiments performed with cells cultured at 37{degrees}C in serum-free medium for 35 h prior to and then during the 12.24 h low-dose-rate radiation exposure. Under these conditions, cell cycle progression, as shown by reduction in growth rate and dual-parameter flow cytometric analysis, was considerable inhibited (cell cycle time increased from 20 h to 40 h), and there was no significant enhancement of cell killing or neoplastic transformation. 23 refs., 2 figs., 1 tab.

  11. LATTICE DYNAMICS NUCLEAR RESONANCE ABSORPTION OF GAMMA-RADIATION

    E-print Network

    Paris-Sud XI, Université de

    LATTICE DYNAMICS NUCLEAR RESONANCE ABSORPTION OF GAMMA-RADIATION AND COHERENT DECAY MODES Institut effets de correlation de paires. Abstract. -The cross-section for nuclear resonance absorption of gamma-radiation rksonnante des radiations gamma est en gBneral calculee en negligeant I'influence des phenomknes de coherence

  12. Diverse delayed effects in human lymphoblastoid cells surviving exposure to high-LET (56)Fe particles or low-LET (137)Cs gamma radiation

    NASA Technical Reports Server (NTRS)

    Evans, H. H.; Horng, M. F.; Ricanati, M.; Diaz-Insua, M.; Jordan, R.; Schwartz, J. L.

    2001-01-01

    To obtain information on the origin of radiation-induced genomic instability, we characterized a total of 166 clones that survived exposure to (56)Fe particles or (137)Cs gamma radiation, isolated approximately 36 generations after exposure, along with their respective control clones. Cytogenetic aberrations, growth alterations, responses to a second irradiation, and mutant frequencies at the Na(+)/K(+) ATPase and thymidine kinase loci were determined. A greater percentage of clones that survived exposure to (56)Fe particles exhibited instability (defined as clones showing one or more outlying characteristics) than in the case of those that survived gamma irradiation. The phenotypes of the unstable clones that survived exposure to (56)Fe particles were also qualitatively different from those of the clones that survived gamma irradiation. A greater percentage (20%) of the unstable clones that survived gamma irradiation than those that survived exposure to (56)Fe particles (4%) showed an altered response to the second irradiation, while an increase in the percentage of clones that had an outlying frequency of ouabain-resistant and thymidine kinase mutants was more evident in the clones exposed to (56)Fe particles than in those exposed to gamma rays. Growth alterations and increases in dicentric chromosomes were found only in clones with more than one alteration. These results underscore the complex nature of genomic instability and the likelihood that radiation-induced genomic instability arises from different original events.

  13. Field Deployable Gamma Radiation Detectors for DHS Use

    SciTech Connect

    Sanjoy Mukhopadhyay

    2007-08-31

    Recently, the U.S. Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS’s requirements in terms of sensitivity, resolution, response time and reach back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron’s identiFINDER™, which primarily uses sodium iodide crystals (3.18-cm x 2.54-cm cylinders) as gamma detector, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack™ that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity (comparable to that of a 7.62-cm x 7.62-cm sodium iodide crystal at low gamma energy ranging from 30 keV to 3,000 keV), better resolution (< 3.0 percent at 662 keV), faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system auto triggers saving of relevant spectral data and software-triggers the digital camera to take a snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format and sent to a command post using an imbedded cell phone.

  14. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Carter, J. R., Jr.; Tada, H. Y.

    1973-01-01

    A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques used in the evaluation of radiation effects. Other topics discussed include: theoretical aspects of radiation damage, methods for developing relative damage coefficients, nature of the space radiation environment, method of calculating equivalent fluence from electron and proton energy spectrums and relative damage coefficients, and comparison of flight data with estimated degradation.

  15. Intrinsic radiation resistance in human chondrosarcoma cells

    SciTech Connect

    Moussavi-Harami, Farid [Departments of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA 52242 (United States); Mollano, Anthony [Departments of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA 52242 (United States); Martin, James A. [Departments of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA 52242 (United States); Ayoob, Andrew [Departments of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA 52242 (United States); Domann, Frederick E. [Department of Radiation Oncology, Iowa City, IA 52245 (United States); Gitelis, Steven [Department of Internal Medicine, Section of Medical Oncology, Chicago, IL 60612 (United States); Department of Orthopaedics Rush-Presbyterian St. Luke's Medical Center, Chicago, IL 60612 (United States); Buckwalter, Joseph A. [Departments of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA 52242 (United States)]. 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.

  16. Composition and apparatus for detecting gamma radiation

    DOEpatents

    Hofstetter, K.J.

    1994-08-09

    A gamma radiation detector and a radioluminescent composition for use therein. The detector includes a radioluminescent composition that emits light in a characteristic wavelength region when exposed to gamma radiation, and means for detecting said radiation. The composition contains a scintillant such as anglesite (PbSO[sub 4]) or cerussite (PbCO[sub 3]) incorporated into an inert, porous glass matrix via a sol-gel process. Particles of radiation-sensitive scintillant are added to, a sol solution. The mixture is polymerized to form a gel, then dried under conditions that preserve the structural integrity and radiation sensitivity of the scintillant. The final product is a composition containing the uniformly-dispersed scintillant in an inert, optically transparent and highly porous matrix. The composition is chemically inert and substantially impervious to environmental conditions including changes in temperature, air pressure, and so forth. It can be fabricated in cylinders, blocks with holes therethrough for flow of fluid, sheets, surface coatings, pellets or other convenient shapes. 3 figs.

  17. SSPM Scintillator Readout for Gamma Radiation Detection

    SciTech Connect

    Baker, S A; Wendelberger, B; Young, J A; Green, J A; Guise, R E; Franks, L

    2011-09-01

    Silicon-based photodetectors offer several benefits relative to photomultiplier tube–based scintillator systems. Solid-state photomultipliers (SSPM) can realize the gain of a photomultiplier tube (PMT) with the quantum efficiency of silicon. The advantages of the solid-state approach must be balanced with adverse trade-offs, for example from increased dark current, to optimize radiation detection sensitivity. We are designing a custom SSPM that will be optimized for green emission of thallium-doped cesium iodide (CsI(Tl)). A typical field gamma radiation detector incorporates thallium doped sodium iodide (NaI(Tl)) and a radiation converter with a PMT. A PMT’s sensitivity peaks in the blue wavelengths and is well matched to NaI(Tl). This paper presents results of photomultiplier sensitivity relative to conventional SSPMs and discusses model design improvements. Prototype fabrications are in progress.

  18. Radiation Sterilization and Food Irradiation Using Gamma Radiation

    NASA Astrophysics Data System (ADS)

    O'Hara, Kevin

    2003-03-01

    Since the introduction of MDS Nordion's first irradiator in the early 1960's, a variety of gamma-processing systems has been developed. Each design is suited to a particular set of requirements - from high-throughput operations of diverse product lots to full automation or batch processing, all using gamma radiation. Gamma irradiator designs include the Centurion irradiator for temperature-sensitive food products like hamburgers and poultry; the Brevion, a compact batch irradiator providing flexibility, timeliness and simplicity on a whole new scale; a JS-10000 irradiator that operates in either automatic or batch mode to enable multipurpose product scheduling and optimum throughput; and, an irradiator that processes full pallets and is ideal for processing high-density products requiring excellent dose uniformity. These innovative irradiator designs help facilities to be more efficient, maximize operating time, improve product turnaround and minimize inventory levels. MDS Nordion's development of improved Point Kernel and Monte Carlo techniques is discussed, including their application in radiation source optimization, production irradiator design and process control. Absorbed-dose calculations also provide insight into the critical areas for dose mapping and routine monitoring, allowing for the optimum placement of dosimeters. Calculations may also be used to determine the absorbed-dose distribution within product, especially in areas of complex geometry such as material interfaces. The use of easily accessible, accurate and validated dose-calculation programs can be used to optimize the irradiation process. Key Words: dosimetry, irradiator design, dose calculation, modelling, modeling, process control, radiation source optimization.

  19. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.

    1977-01-01

    Solar cell theory cells are manufactured, and how they are modeled mathematically is reviewed. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.

  20. Inactivation of bacteria in sewage sludge by gamma radiation.

    PubMed

    Pandya, G A; Kapila, S; Kelkar, V B; Negi, S; Modi, V V

    1987-01-01

    The survival of certain bacterial cultures suspended in sewage sludge and exposed to gamma-radiation was studied. The inactivation patterns of most of the organisms were significantly different when irradiation was performed using sewage samples collected in the summer and monsoon seasons. The summer sample collected from the anaerobic digestor afforded significant protection to both Gram negative and Gram positive organisms. This was evident by the increase in dose required to bring about a 6 log cycle reduction in viable count of the bacterial cultures, when suspended in sewage samples instead of phosphate buffer. The observations made using monsoon digestor samples were quite different. This sewage sludge greatly enhanced inactivation by gamma-radiation in most cases. The effects of certain chemicals on the inactivation patterns of two organisms-Salmonella typhi and Shigella flexneri-were examined. Arsenate, mercury and lead salts sensitised S. typhi, while barium acetate and sodium sulphide protected this culture against gamma-radiation. In the case of Sh. flexneri, barium acetate and iodacetamide proved to be radioprotectors. The effects of some chemicals on the inactivation pattern of Sh. flexneri cells irradiated in sludge are also discussed. PMID:15092791

  1. Do altered activities of superoxide dismutases and the level of NF-?B modulate the effects of gamma radiation in HeLaS3 cells?

    Microsoft Academic Search

    MIROSLAV AD I?; SNE ANA D. SPASI?; MARIJA B. RADOJ?I?

    Most experimental models, including cell culture studies, have demon- strated that over-expression of manganese superoxide dismutase (MnSOD) in cells bearing a carcinoma phenotype has anti-proliferative and tumour suppression chara- cteristics. In contrast, when cervical carcinoma biopsies express MnSOD, there is a poor prognosis and resistance to radiation therapy. The results herein indicate that human cervical adenocarcinoma (HeLaS3) cells have increased

  2. Radiation chemistry of aqueous solutions of cyanamide. [Gamma radiation

    Microsoft Academic Search

    Z. D. Draganic; I. G. Draganic; S. V. Jovanovic

    1978-01-01

    Oxygen-free aqueous solutions of 0.1 M NHâCN (pH 2.4 and 5) were irradiated with ..gamma.. rays (0.01--25 Mrad). The rate constants determined in competition experiments are: k(H + NHâCN) = 6.7 x 10⁶ M⁻¹ sec⁻¹, k(e\\/sub aq\\/⁻ + NHâCN) = 1.5 x 10⁹ M⁻¹ sec⁻¹, and k(OH + NHâCN) = 8.5 x 10⁶ M⁻¹ sec⁻¹. Radiation-chemical yields were determined for

  3. Gamma radiation effects on nestling Tree Swallows

    SciTech Connect

    Zach, R.; Mayoh, K.R.

    1984-10-01

    The sensitivity of Tree Swallows (Tachycineta bicolor) to the stress of ionizing radiation was investigated with growth analysis. Freshly hatched nestlings were temporarily removed from nests, taken to the laboratory and acutely exposed to 0.9, 2.7, or 4.5 Gy gamma radiation. Some of the unirradiated control nestlings were also taken to the laboratory whereas others were left in the nests. Growth of all the nestlings was measured daily and analyzed by fitting growth models. There was no detectable radiation-induced mortality up to fledgling, approx. = 20 d after irradiation. Radiation exposure did not affect the basic growth pattern; the logistic growth model was most suitable for body mass and foot length, and the von Bertalanffy model for primary-feather length, irrespective of treatment. Parameter values from these models indicated pronounced growth depression in the 2.7-Gy and 4.5-Gy groups, particularly for body mass. Radiation also affected the timing of development. The growth depression of the 2.7-Gy group was similar to that caused by hatching asynchrony in unirradiated nestlings. The 4.5-Cy nestlings grew as well as unexposed nestlings that died from natural causes. Chronic irradiation at approx. = 1.0 Cy/d caused more severe growth effects than acute exposure to 4.5 Gy and may have caused permanent stunting. Growth analysis is a potent tool for assessing man-made environmental stresses. Observed body-mass statistics and model parameters seem to be most sensitive to environmental stresses, but coefficients of variation are not necessarily correlated with sensitivity. 34 references, 2 figures, 4 tables.

  4. Orchid flowers tolerance to gamma-radiation

    NASA Astrophysics Data System (ADS)

    Kikuchi, Olivia Kimiko

    2000-03-01

    Cut flowers are fresh goods that may be treated with fumigants such as methyl bromide to meet the needs of the quarantine requirements of importing countries. Irradiation is a non-chemical alternative to substitute the methyl bromide treatment of fresh products. In this research, different cut orchids were irradiated to examine their tolerance to gamma-rays. A 200 Gy dose did inhibit the Dendrobium palenopsis buds from opening, but did not cause visible damage to opened flowers. Doses of 800 and 1000 Gy were damaging because they provoked the flowers to drop from the stem. Cattleya irradiated with 750 Gy did not show any damage, and were therefore eligible for the radiation treatment. Cymbidium tolerated up to 300 Gy and above this dose dropped prematurely. On the other hand, Oncydium did not tolerate doses above 150 Gy.

  5. Carbohydrate based materials for gamma radiation shielding

    NASA Astrophysics Data System (ADS)

    Tabbakh, F.; Babaee, V.; Naghsh-Nezhad, Z.

    2015-05-01

    Due to the limitation in using lead as a shielding material for its toxic properties and limitation in abundance, price or non-flexibility of other commonly used materials, finding new shielding materials and compounds is strongly required. In this conceptual study carbohydrate based compounds were considered as new shielding materials. The simulation of radiation attenuation is performed using MCNP and Geant4 with a good agreement in the results. It is found that, the thickness of 2 mm of the proposed compound may reduce up to 5% and 50% of 1 MeV and 35 keV gamma-rays respectively in comparison with 15% and 100% for the same thickness of lead.

  6. Inhaled /sup 147/Pm and/or total-body gamma radiation: Early mortality and morbidity in rats

    SciTech Connect

    Filipy, R.E.; Lauhala, K.E.; McGee, D.R.; Cannon, W.C.; Buschbom, R.L.; Decker, J.R.; Kuffel, E.G.; Park, J.F.; Ragan, H.A.; Yaniv, S.S.; Scott, B.R.

    1989-05-01

    Rats were given doses of /sup 60/Co gamma radiation and/or lung burdens of /sup 147/Pm (in fused aluminosilicate particles) within lethal ranges in an experiment to determine and compare morbidity and mortality responses for the radiation insults within 1 year after exposure. Radiation-induced morbidity was assessed by measuring changes in body weights, hematologic parameters, and pulmonary-function parameters. Acute mortality and morbidity from inhaled promethium were caused primarily by radiation pneumonitis and pulmonary fibrosis that occurred more than 53 days after exposure. Acute mortality and morbidity from total-body gamma irradiation occurred within 30 days of exposure and resulted from the bone-marrow radiation syndrome. Gamma radiation caused transient morbidity, reflected by immediately depressed blood cell levels and by reduced body weight gain in animals that survived the acute gamma radiation syndrome. Inhaled promethium caused a loss of body weight and diminished pulmonary function, but its only effect on blood cell levels was lymphocytopenia. Combined gamma irradiation and promethium lung burdens were synergistic, in that animals receiving both radiation insults had higher morbidity and mortality rates than would be predicted based on the effect of either kind of radiation alone. Promethium lung burdens enhanced the effect of gamma radiation in rats within the first 30 days of exposure, and gamma radiation enhanced the later effect of promethium lung burdens. 70 refs., 68 figs., 21 tabs.

  7. Pulsar and diffuse contributions to the observed galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Stecker, F. W.

    1980-01-01

    With the acquisition of satellite data on the energy spectrum of galactic gamma-radiation, it is clear that such radiation has a multicomponent nature. A calculation of the pulsar gamma ray emission spectrum is used together with a statistical analysis of recent data on 328 known pulsars to make a new determination of the pulsar contribution to galactic gamma ray emission. The contributions from diffuse interstellar cosmic ray induced production mechanisms to the total emission are then reexamined. It is concluded that pulsars may account for a significant fraction of galactic gamma ray emission.

  8. RADIATION SENSITIVITY & PROCESSING OF DNA DAMAGE FOLLOWING LOW DOSES OF GAMMA-RAY ALPHA PARTICLES & HZE IRRADIATION OF NORMAL DSB REPAIR DEFICIENT CELLS

    SciTech Connect

    O'Neil, Peter

    2009-05-15

    Non-homologous end joining (NHEJ) predominates in the repair of DNA double strand breaks (DSB) over homologous recombination (HR). NHEJ occurs throughout the cell cycle whereas HR occurs in late S/G2 due to the requirement of a sister chromatid (Rothkamm et al, Mol Cell Biol 23 5706-15 [2003]). To date evidence obtained with DSB repair deficient cells using pulsed-field gel electrophoresis has revealed the major pathway throughout all phases of the cell cycle for processing high dose induced DSBs is NHEJ (Wang et al, Oncogene 20 2212-24 (2001); Pluth et al, Cancer Res. 61 2649-55 [2001]). These findings however were obtained at high doses when on average >> 20-30 DSBs are formed per cell. The contribution of the repair pathways (NHEJ and HR) induced in response to DNA damage during the various phases of the cell cycle may depend upon the dose (the level of initial DSBs) especially since low levels of DSBs are induced at low dose. To date, low dose studies using NHEJ and HR deficient mutants have not been carried out to address this important question with radiations of different quality. The work presented here leads us to suggest that HR plays a relatively minor role in the repair of radiation-induced prompt DSBs. SSBs lead to the induction of DSBs which are associated specifically with S-phase cells consistent with the idea that they are formed at stalled replication forks in which HR plays a major role in repair. That DNA-PKcs is in some way involved in the repair of the precursors to replication-induced DSB remains an open question. Persistent non-DSB oxidative damage also leads to an increase in RAD51 positive DSBs. Both simple and complex non-DSB DNA damage may therefore contribute to indirect DSBs induced by ionising radiation at replication forks.

  9. Gamma Radiation Induced Degradation of Operating Quantum Dot Lasers

    Microsoft Academic Search

    J. W. Mares; J. Harben; A. V. Thompson; D. W. Schoenfeld; W. V. Schoenfeld

    2008-01-01

    The degradation of quantum dot lasers (QDLs) due to 1.17 and 1.22 MeV gamma radiation is characterized by changes in threshold current, external slope efficiency and light output. Both operating and non-operating lasers were exposed to a Co-60 source, providing gamma radiation at a dose rate of 0.4 kGy\\/hr to a total absorbed dose of 1.6 MGy. Degradation rates of

  10. Radiation oncogenesis in cell culture

    SciTech Connect

    Borek, C.

    1982-01-01

    This review article examines the oncogenic effects of radiation with emphasis on ionizing radiations. Cell transformation in vitro is examined with respect to culture systems currently used in these studies, initiation and phenotypic expression of transformation and criteria for transformation. The section of radiation oncogenesis in vitro includes ionizing and nonionizing radiation studies and cocarcinogens and modulators of radiogenic transformations.

  11. An integrated view of gamma radiation effects on marine fauna: from molecules to ecosystems.

    PubMed

    Won, Eun-Ji; Dahms, Hans-U; Kumar, K Suresh; Shin, Kyung-Hoon; Lee, Jae-Seong

    2014-11-11

    Accidental release of nuclides into the ocean is causing health risks to marine organisms and humans. All life forms are susceptible to gamma radiation with a high variation, depending on various physical factors such as dose, mode, and time of exposure and various biological factors such as species, vitality, age, and gender. Differences in sensitivity of gamma radiation are also associated with different efficiencies of mechanisms related to protection and repair systems. Gamma radiation may also affect various other integration levels: from gene, protein, cells and organs, population, and communities, disturbing the energy flow of food webs that will ultimately affect the structure and functioning of ecosystems. Depending on exposure levels, gamma radiation induces damages on growth and reproduction in various organisms such as zooplankton, benthos, and fish in aquatic ecosystems. In this paper, harmful effects of gamma-irradiated aquatic organisms are described and the potential of marine copepods in assessing the risk of gamma radiation is discussed with respect to physiological adverse effects that even affect the ecosystem level. PMID:25382502

  12. Alpha Gamma Hot Cell Facility

    E-print Network

    Kemner, Ken

    with radiation detectors are being deployed in the facility to help AGHCF perform remote and continuous of personnel to radiation. ARG-US RFID System Deployment Six radiation-detector-enabled tags have been set up PROGRAM Contact: Yung Y. Liu Senior Nuclear Engineer, Section Manager Argonne National Laboratory yyliu

  13. Impacts of Low-Dose Gamma-Radiation on Genotoxic Risk in Aquatic Ecosystems

    PubMed Central

    Cassidy, Cheryl L.; Lemon, Jennifer A.; Boreham, Douglas R.

    2007-01-01

    Chinook salmon cells were exposed to gamma radiation and chromosome damage was assessed using the micronucleus assay. The salmon cells were resistant to radiation at all doses compared to human and mammalian cells. We used an indirect approach to determine if prior low dose exposures at environmental dose levels might alter the consequences of radiation exposures to high doses of radiation (adaptive response). The cells adapted but only at doses which were above levels that might be expected environmentally. The “adaptive response” endpoint was useful to show biological responses to exposure, however, under these conditions it might not help in risk assessment of aquatic organisms since the cells seem to be very resistant and environmental radiation levels are typically extremely low. Preliminary experiments were conducted on two other fish cell model systems (Rainbow Trout and Medaka) to optimize conditions for the micronucleus assay for future environmental radiation studies. Since fish cells appear to be more radiation resistant than mammalian cells, we postulate that radiation risk in the whole organism may also be lower. Therefore whole body studies designed to test effects with the specific aim of assessing relative risk between species are in process. PMID:18648569

  14. Curcumin Regulates Low-Linear Energy Transfer {gamma}-Radiation-Induced NF{kappa}B-Dependent Telomerase Activity in Human Neuroblastoma Cells

    SciTech Connect

    Aravindan, Natarajan, E-mail: naravind@ouhsc.ed [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States); Veeraraghavan, Jamunarani; Madhusoodhanan, Rakhesh; Herman, Terence S. [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (United States); Natarajan, Mohan [Department of Otolaryngology, Head and Neck Surgery, University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States)

    2011-03-15

    Purpose: We recently reported that curcumin attenuates ionizing radiation (IR)-induced survival signaling and proliferation in human neuroblastoma cells. Also, in the endothelial system, we have demonstrated that NF{kappa}B regulates IR-induced telomerase activity (TA). Accordingly, we investigated the effect of curcumin in inhibiting IR-induced NF{kappa}B-dependent hTERT transcription, TA, and cell survival in neuroblastoma cells. Methods and Materials: SK-N-MC or SH-SY5Y cells exposed to IR and treated with curcumin (10-100 nM) with or without IR were harvested after 1 h through 24 h. NF{kappa}B-dependent regulation was investigated either by luciferase reporter assays using pNF{kappa}B-, pGL3-354-, pGL3-347-, or pUSE-I{kappa}B{alpha}-Luc, p50/p65, or RelA siRNA-transfected cells. NF{kappa}B activity was analyzed using an electrophoretic mobility shift assay and hTERT expression using the quantitative polymerase chain reaction. TA was determined using the telomerase repeat amplification protocol assay and cell survival using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertrazolium bromide and clonogenic assay. Results: Curcumin profoundly inhibited IR-induced NF{kappa}B. Consequently, curcumin significantly inhibited IR-induced TA and hTERT mRNA at all points investigated. Furthermore, IR-induced TA is regulated at the transcriptional level by triggering telomerase reverse transcriptase (TERT) promoter activation. Moreover, NF{kappa}B becomes functionally activated after IR and mediates TA upregulation by binding to the {kappa}B-binding region in the promoter region of the TERT gene. Consistently, elimination of the NF{kappa}B-recognition site on the telomerase promoter or inhibition of NF{kappa}B by the I{kappa}B{alpha} mutant compromises IR-induced telomerase promoter activation. Significantly, curcumin inhibited IR-induced TERT transcription. Consequently, curcumin inhibited hTERT mRNA and TA in NF{kappa}B overexpressed cells. Furthermore, curcumin enhanced the IR-induced inhibition of cell survival. Conclusions: These results strongly suggest that curcumin inhibits IR-induced TA in an NF{kappa}B dependent manner in human neuroblastoma cells.

  15. Semiconductors in the nuclear weapon gamma radiation environment. I - Prediction of gamma radiation effects. II - Verification of predictions

    Microsoft Academic Search

    A. R. Edwards; M. A. Hardman; R. Williamson

    1985-01-01

    The effects of gamma radiation on the performance of MOS and NMOS devices is considered. The different methods used to predict the ability of an IC to survive a hostile nuclear environment are described including latch-up analysis and topographic analysis. A formula is derived for predicting the failure probability of an IC in relation to the radiation dose in rads.

  16. Radiation inactivation of human gamma-interferon: cellular activation requires two dimers.

    PubMed Central

    Langer, J A; Rashidbaigi, A; Garotta, G; Kempner, E

    1994-01-01

    gamma-Interferon (IFN-gamma) is a 17-kDa broad-spectrum cytokine which exerts its effects on a variety of target cells through its interaction with the IFN-gamma receptor. Although physicochemical studies of Escherichia coli-derived IFN-gamma, as well as its crystal structure, demonstrate that it is a homodimer in solution (M(r) 34,000), previous radiation inactivation studies yielded a functional size for IFN-gamma of 63-73 kDa in an antiviral assay. To understand the relationship between the solution form of IFN-gamma and the moiety that actually binds to the cellular receptor and activates cells, we examined irradiated nonradioactive and 32P-labeled IFN-gamma for its migration in SDS/polyacrylamide gels (to determine its physical integrity), its binding to cells, its reactivity in an ELISA, and its antiviral activity. The functional size of IFN-gamma differed in the assays, being 22 +/- 2 kDa for the physical destruction of IFN-gamma, 56 +/- 2 kDa for the cellular binding assay, 45-50 kDa for reactivity in the ELISA, and 72 +/- 6 kDa for antiviral activity. The results from the binding assays constitute direct evidence that IFN-gamma binds to its cellular receptor as a dimer. However, for antiviral activity, the functional mass is equivalent to a tetramer. This is consistent with models involving ligand-induced receptor dimerization, whereby two dimers acting in concert (equivalent to the target size of a tetramer) are required to activate cells in the antiviral assay. Images PMID:8016072

  17. High resolution room temperature ionization chamber xenon gamma radiation detector

    Microsoft Academic Search

    Gary Tepper; Jon Losee

    1995-01-01

    A unique thin walled dual-type gridded ionization chamber gamma radiation detector using ultra pure Xe gas as the detection medium is described. The detector was operated at room temperature and the energy spectra of 60Co, 137Cs, 22Na and 133Ba were obtained. An energy resolution of (16 keV) 2.4% FWHM was determined for the 662 keV 137Cs gamma peak which is

  18. Radiative Transfer Models for Gamma-Ray Bursts

    E-print Network

    Vurm, Indrek

    2015-01-01

    We present global radiative transfer models for heated relativistic jets. The simulations include all relevant radiative processes, starting deep in the opaque zone and following the evolution of radiation to and beyond the photosphere of the jet. The transfer models are compared with three gamma-ray bursts GRB 990123, GRB 090902B, and GRB 130427A, which have well-measured and different spectra. The models provide good fits to the observed spectra in all three cases. The fits give estimates for the jet magnetization parameter $\\varepsilon_{\\rm B}$ and the Lorentz factor $\\Gamma$. In the small sample of three bursts, $\\varepsilon_{\\rm B}$ varies between 0.01 and 0.1, and $\\Gamma$ varies between 340 and 1200.

  19. Gamma and neutrino radiation dose from gamma ray bursts and nearby supernovae.

    PubMed

    Karam, P Andrew

    2002-04-01

    Supernovae and gamma ray bursts are exceptionally powerful cosmic events that occur randomly in space and time in our galaxy. Their potential to produce very high radiation levels has been discussed, along with speculation that they may have caused mass extinctions noted from the fossil record. It is far more likely that they have produced radiation levels that, while not lethal, are genetically significant, and these events may have influenced the course of evolution and the manner in which organisms respond to radiation insult. Finally, intense gamma radiation exposure from these events may influence the ability of living organisms to travel through space. Calculations presented in this paper suggest that supernovae and gamma ray bursts are likely to produce sea-level radiation exposures of about I Gy with a mean interval of about five million years and sea-level radiation exposures of about 0.2 Gy every million years. Comets and meteors traveling through space would receive doses in excess of 10 Gy at a depth of 0.02 m at mean intervals of 4 and 156 million years, respectively. This may place some constraints on the ability of life to travel through space either between planets or between planetary systems. Calculations of radiation dose from neutrino radiation are presented and indicate that this is not a significant source of radiation exposure for even extremely close events for the expected neutrino spectrum from these events. PMID:11906138

  20. A study of the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.

    1982-01-01

    Assuming cosmic rays pervade the Galaxy, they necessarily produced high energy gamma-rays as they interact with the instellar matter and photons. The cosmic ray nucleon interactions five rise to gamma rays primarily through the decay of pi mesons, giving a unique spectrum with a maximum at approximately 68 MeV. Cosmic ray electrons produce gamma rays through bremsstrahlung, but with a markedly different energy spectral shape, one which decreases monotonically with energy. Cosmic ray electrons also interact with the interstellar starlight, optical and infrared photons, and the blackbody radiation through the Compton process. A model of galactic gamma ray production is discussed, and the predicted spatial distribution and energy spectra are presented. Considering the uncertainty in the point source contributions, the agreement between the theoretical predictions and the gamma ray data seems quite reasonable.

  1. Radiation effects in solar cells

    NASA Astrophysics Data System (ADS)

    Imaizumi, Mitsuru; Ohshima, Takeshi

    2013-05-01

    Two types of space solar cells, silicon single-junction and InGaP/GaAs/Ge triple-junction (3J) solar cells, have been primarily adopted for spacecraft. The conversion efficiencies of the solar cells under AM0, 1 sun condition are ~17% for silicon and ~30% for 3J cells. Radiation degradation occurs in space due to high-energy electrons and protons existing in space environment. The degradation is caused by radiation induced crystal defects which act as minority-carrier recombination centers and majority-carrier trap centers. The 3J cells are superior radiation resistant to the silicon cells, and this is mainly because the InGaP top-subcell has property of very high radiation resistance.

  2. Effect of gamma radiation on dentin bond strength and morphology.

    PubMed

    Sperandio, M; Souza, J B; Oliveira, D T

    2001-01-01

    Sterilization by gamma radiation is a method often used for bone and extracted teeth banking. The bond strength of human dentin submitted to gamma rays has not been reported. Therefore, the aim of this study was to assess the effect of gamma radiation on dentin shear bond strength and morphology. The roots were removed from extracted human bicuspids and their crowns divided into two groups: an untreated control and crowns submitted to gamma radiation sterilization. The crowns were mounted in epoxy resin and the buccal enamel removed exposing the subjacent dentin. SBMPPlus adhesive system was applied to a 3-mm diameter area after 15 s of 35% phosphoric acid etching. The samples were mounted in composite resin cylinders and stored in distilled water at 37 degrees C for 24 h until the shear test. Dental fragments from both groups were prepared for SEM analysis. There was no statistically significant difference between the results of the shear test for the two groups according to the Tukey test (p > 0.05). Scanning electron micrographs also did not show alterations. These results indicate that gamma radiation neither affected the shear bond strength of SBMPPlus nor altered the dentin surface morphology. PMID:11696920

  3. Annual effective dose from environmental gamma radiation in Bushehr city

    PubMed Central

    2014-01-01

    Background Present study was an attempt to measure outdoor and indoor gamma dose rates in Bushehr city to determine corresponding annual effective dose and, to assess effect of active nuclear power plant located in Bushehr city on background radiation level of this city. Methods All measurements were performed by G.M (Geiger Muller) detector (X5C plus) calibrated in Iran Atomic Energy Agency. In order to avoid effects of ground on outdoor and indoor measurements, G.M detector was placed one meter higher than ground level. Also, during the outdoor measurements, G.M detector was used at least six meters away from the walls of any building nearby to avoid unwanted effects of the materials used in the buildings on measurements. Results Average gamma dose rates of outdoor and indoor measurements were determined as 51.8?±?8.8 nSv/h and 60.2?±?7.2 nSv/h, respectively. Annual effective dose due to background gamma radiation was calculated as 0.36 mSv which was lower than average global level. Conclusions The average annual effective dose from background gamma radiation in Bushehr city was less than global level. Comparison of the results of present study, as follow up, with previous attempt performed in 2004 to determine effective dose of environmental gamma radiation in Bushehr province revealed that, during eight years, nuclear power plant located in this city has not significantly increased level of annual effective dose of Bushehr city. PMID:24393421

  4. Gamma line radiation from supernovae. [nucleosynthesis

    NASA Technical Reports Server (NTRS)

    Arnett, W. D.

    1978-01-01

    Recent calculations of core collapse or massive stars result in explosive ejection of the mantle by a reflected shock. These hydrodynamic results are important for predictions of explosive nucleosynthesis and gamma-ray line emission from supernovae. Previous estimates, based on simple parameterized models or the nucleosynthesis in an average supernova, are compared with these latest results.

  5. Measurements of background gamma radiation on Spacelab 2

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Paciesas, W. S.; Gregory, J. C.

    1987-01-01

    A nuclear radiation monitor (NRM) which was flown as part of the verification instrumentation on the Spacelab 2 mission (July 29 - August 6, 1985) recorded spectra every 20 seconds and counting rates in coarse energy bands on finer time scales. The gamma radiation environment on Spacelab is characterized by cosmic-ray and trapped proton secondary radiation in the Spacelab/Shuttle, earth albedo radiation, and delayed induced radioactivity in the detector and surrounding materials. It is found that passages through South Atlantic Anomaly protons produce a well-defined background enhancement.

  6. Radiative cooling for solar cells

    NASA Astrophysics Data System (ADS)

    Zhu, Linxiao; Raman, Aaswath; Wang, Ken X.; Anoma, Marc A.; Fan, Shanhui

    2015-03-01

    Standard solar cells heat up under sunlight, and the resulting increased temperature of the solar cell has adverse consequences on both its efficiency and its reliability. We introduce a general approach to radiatively lower the operating temperature of a solar cell through sky access, while maintaining its sunlight absorption. We present first an ideal scheme for the radiative cooling of solar cells. For an example case of a bare crystalline silicon solar cell, we show that the ideal scheme can passively lower the operating temperature by 18.3 K. We then show a microphotonic design based on realistic material properties, that approaches the performance of the ideal scheme. We also show that the radiative cooling effect is substantial, even in the presence of significant non-radiative heat change, and parasitic solar absorption in the cooling layer, provided that we design the cooling layer to be sufficiently thin.

  7. GAMMA RADIATION TREATMENT OF WATERS FROM LIGNITE MINES

    EPA Science Inventory

    Discussed in this report are results of laboratory investigations carried out with the application of gamma radiation for the purification of waters drained from surface lignite mines. These waters are polluted to a considerable extent with suspended matter of various sizes, a la...

  8. The Effects of Co60 Gamma Radiation on MOS Diodes

    Microsoft Academic Search

    R. J. Mattauch; R. W. Lade

    1967-01-01

    MOS diodes were fabricated on silicon substrates and exposed to Co60 gamma radiation. A change in both surface state density and oxide charge density was noted. Non-irradiation annealing studies were carried out to determine the nature of the oxide charge. It was deduced on the basis of annealing data that the oxide charge was due to mobile alkali ions. The

  9. The role of contacts in semiconductor gamma radiation detectors

    Microsoft Academic Search

    Uri Lachish

    1998-01-01

    It is proposed that the operation of semiconductor gamma radiation detectors, equipped with ohmic contacts, which allow free electron flow between the contacts and bulk material, will not be sensitive to low hole mobility, hole collection efficiency, or hole trapping. Such fast-operating detectors may be readily integrated into monolithic arrays. The detection mechanism and various material aspects are discussed and

  10. Thermal Radiation from Gamma-ray Burst Jets

    Microsoft Academic Search

    Akira Mizuta; Shigehiro Nagataki; Junichi Aoi

    2011-01-01

    In this study, the light curves and spectrum of the photospheric thermal radiation from ultrarelativistic gamma-ray burst (GRB) jets are calculated using two-dimensional relativistic hydrodynamic simulations of jets from a collapsar. As the jet advances, the density around the head of the jet decreases, and its Lorentz factor reaches as high as 200 at the photosphere and 400 inside the

  11. Integrated beta and gamma radiation dose calculations for the ferrocyanide waste tanks

    SciTech Connect

    Parra, S.A.

    1994-11-30

    This report contains the total integrated beta and gamma radiation doses in all the ferrocyanide waste tanks. It also contains estimated gamma radiation dose rates for all single-shell waste tanks containing a liquid observation well.

  12. Gamma Radiation from PSR B1055-52

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bailes, M.; Bertsch, D. L.; Cordes, J.; DAmico, N. D.; Esposito, J. A.; Finley, J.; Hartman, R. C.; Hermsen, W.; Kanbach, G.; Kaspi, V. M.; Kniffen, D. A.; Kuiper, L.; Lin, Y. C.; Lyne, A.; Manchester, R.; Matz, S. M.; Mayer-Hasselwander, H. A.; Michelson, P. F.; Nolan, P. L.

    1998-01-01

    The telescopes on the Compton Gamma Ray Observatory (CCRO) have observed PSR B1055-52 a number of times between 1991 and 1998. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics which distinguish this pulsar: the light curve is complex; there is no detectable unpulsed emission; the energy spectrum is flat, with no evidence of a sharp high-energy cutoff up to greater than 4 GeV. Comparisons of the gamma-ray data with observations at longer wavelengths show that no two of the known gamma-ray pulsars have quite the same characteristics; this diversity makes interpretation in terms of theoretical models difficult.

  13. Gamma Radiation from PSR B1055-52

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bailes, M.; Bertsch, D. L.; Cordes, J.; DAmico, N.; Esposito, J. A.; Finley, J.; Hartman, R. C.; Hermsen, W.; Kanbach, G.; Kaspi, V. M.; Kniffen, D. A.; Kuiper, L.; Lin, Y. C.; Lyne, A.; Manchester, R.; Matz, S. M.; Mayer-Hasselwander, H. A.; Michelson, P. F.; Nolan, P. L.

    1999-01-01

    The telescopes on the Compton Gamma Ray Observatory (CGRO) have observed PSR B1055-52 a number of times between 1991 and 1998. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics which distinguish this pulsar: the light curve is complex; there is no detectable unpulsed emission; the energy spectrum is flat, with no evidence of a sharp high-energy cutoff up to greater than 4 GeV. Comparisons of the gamma-ray data with observations at longer wavelengths show that no two of the known gamma-ray pulsars have quite the same characteristics; this diversity makes interpretation in terms of theoretical models difficult.

  14. Parametric gamma-radiation at the anomalous passage conditions

    NASA Astrophysics Data System (ADS)

    Ahmadi, Abbas; Feranchuk, Ilya

    2014-10-01

    Dynamical diffraction theory of the parametric gamma-radiation (PGR) from relativistic electrons in a thick crystal with Mössbauer nuclei is considered. A detailed analysis of the influence of suppression of photoabsorption for the radiated ?-quanta at an ideal single crystal is presented taking into account both nuclear resonance and electron scattering of the photons. The obtained results allow one to choose the optimal conditions for the observation of the ?-quanta anomalous passage at the Laue case. It is shown that the radiation intensity is drastically increased at such conditions.

  15. Characterization of an Escherichia coli mutant (radB101) sensitive to. gamma. and uv radiation, and methyl methanesulfonate

    SciTech Connect

    Sargentini, N.J.; Smith, K.C.

    1983-03-01

    After N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Escherichia coli K-12 (xthA14), an X-ray-sensitive mutant was isolated. This sensitivity is due to a mutation, radB101, which is located at 56.5 min on the E.coli K-12 linkage map. The radB101 mutation sensitized wild-type cells to ..gamma.. and uv radiation, and to methyl methanesulfonate. When known DNA repair-deficient mutants were ranked for their ..gamma..-radiation sensitivity relative to their uv-radiation sensitivity, their order was (starting with the most selectively ..gamma..-radiation-sensitive strain): recB21, radB101, wild type, polA1, recF143, lexA101, recA56, uvrD3, and uvrA6. The radB mutant was normal for ..gamma..- and uv-radiation mutagenesis, it showed only a slight enhancement of ..gamma..- and uv-radiation-induced DNA degradation, and it was approx. 60% deficient in recombination ability. The radB gene is suggested to play a role in the recA gene-dependent (Type III) repair of DNA single-strand breaks after ..gamma.. irradiation and in postreplication repair after uv irradiation for the following reasons: the radB strain was normal for the host-cell reactivation of ..gamma..- and uv-irradiated bacteriophage lambda; the radB mutation did not sensitize a recA strain, but did sensitize a polA strain to ..gamma.. and uv radiation; the radB mutation sensitized a uvrB strain to uv radiation.

  16. Semiconductors in the nuclear weapon gamma radiation environment. I - Prediction of gamma radiation effects. II - Verification of predictions

    NASA Astrophysics Data System (ADS)

    Edwards, A. R.; Hardman, M. A.; Williamson, R.

    The effects of gamma radiation on the performance of MOS and NMOS devices is considered. The different methods used to predict the ability of an IC to survive a hostile nuclear environment are described including latch-up analysis and topographic analysis. A formula is derived for predicting the failure probability of an IC in relation to the radiation dose in rads. The design of a linear accelerator radiation simulator for testing semiconductor devices is described, and the results of recent calibration tests are presented.

  17. Radiation protection by disulfiram: protection of membrane and DNA in vitro and in vivo against gamma-radiation.

    PubMed

    Gandhi, Nitin Motilal; Gopalaswamy, Usulumarty Venu; Nair, Cherupally rishnan K

    2003-09-01

    Disufiram (a drug used for the treatment of alcoholism) protected microsomal membranes and plasmid DNA against damages induced by gamma-radiation. The peroxidation of membrane lipids increased linearly with the radiation dose up to 600 Gy, and the presence of disulfiram inhibited membrane lipid peroxidation as assayed by the presence of thiobarbituric acid reacting substances. The reduction of the quantity of the supercoiled (ccc) form of plasmid pBR322 DNA is directly related to the radiation-induced damage, particularly to DNA strand breaks. There was a complete protection of plasmid DNA when exposed to gamma-radiation in the presence of disufiram (0.1 mM) at 300 Gy. This drug also protected deoxyribose against damages caused by hydroxyl radicals produced by the Fenton reaction. The administration of DSF to mice prior to whole-body radiation exposure (4 Gy) resulted in a reduction of peroxidation of membrane lipids in mice liver as well as a decrease in radiation-induced damage to cellular DNA, as assayed by single-cell gel electrophoresis (comet assay). The results thus suggest the possible use of DSF as a radioprotector. PMID:14646230

  18. Characterization of gamma radiation inducible thioredoxin h from Spirogyra varians.

    PubMed

    Yoon, Minchul; Yang, Ho-Yeon; Lee, Seung-Sik; Kim, Dong-Ho; Kim, Gwang-Hoon; Choi, Jong-il

    2013-08-15

    In this study, thioredoxin h (Trxh) was isolated and characterized from the fresh water green alga Spirogyra varians, which was one amongst the pool of proteins induced upon gamma radiation treatment. cDNA clones encoding S. varians thioredoxin h were isolated from a pre-constructed S. varians cDNA library. Trxh had a molecular mass of 13.5kDa and contained the canonical WCGPC active site. Recombinant Trxh showed the disulfide reduction activity, and exhibited insulin reduction activity. Also, Trxh had higher 5,5'-dithiobis(2-nitrobenzoic acid) reduction activity with Arabidopsis thioredoxin reductase (TR) than with Escherichia coli TR. Specific expression of the Trxh gene was further analyzed at mRNA and protein levels and was found to increase by gamma irradiation upto the absorbed dose of 3kGy, suggesting that Trxh may have potential functions in protection of biomolecules from gamma irradiation. PMID:23830452

  19. Optical Sensors for Monitoring Gamma and Neutron Radiation

    NASA Technical Reports Server (NTRS)

    Boyd, Clark D.

    2011-01-01

    For safety and efficiency, nuclear reactors must be carefully monitored to provide feedback that enables the fission rate to be held at a constant target level via adjustments in the position of neutron-absorbing rods and moderating coolant flow rates. For automated reactor control, the monitoring system should provide calibrated analog or digital output. The sensors must survive and produce reliable output with minimal drift for at least one to two years, for replacement only during refueling. Small sensor size is preferred to enable more sensors to be placed in the core for more detailed characterization of the local fission rate and fuel consumption, since local deviations from the norm tend to amplify themselves. Currently, reactors are monitored by local power range meters (LPRMs) based on the neutron flux or gamma thermometers based on the gamma flux. LPRMs tend to be bulky, while gamma thermometers are subject to unwanted drift. Both electronic reactor sensors are plagued by electrical noise induced by ionizing radiation near the reactor core. A fiber optic sensor system was developed that is capable of tracking thermal neutron fluence and gamma flux in order to monitor nuclear reactor fission rates. The system provides near-real-time feedback from small- profile probes that are not sensitive to electromagnetic noise. The key novel feature is the practical design of fiber optic radiation sensors. The use of an actinoid element to monitor neutron flux in fiber optic EFPI (extrinsic Fabry-Perot interferometric) sensors is a new use of material. The materials and structure used in the sensor construction can be adjusted to result in a sensor that is sensitive to just thermal, gamma, or neutron stimulus, or any combination of the three. The tested design showed low sensitivity to thermal and gamma stimuli and high sensitivity to neutrons, with a fast response time.

  20. Characterization of muon and gamma radiations at the PTOLEMY site

    NASA Astrophysics Data System (ADS)

    Betts, Susannah; Gentile, Charles; Tully, Chris; Zapata, Sandra; Chris Tully Collaboration

    2013-10-01

    PTOLEMY is an experimental project at Princeton Plasma Physics Laboratory designed to determine the present day number density of relic neutrinos through measurement of electrons produced from neutrino capture on tritium. The weak interaction cross section for relic neutrino interactions necessitates high sensitivity measurements that could be influenced by high energy particles, like muons and gamma ray photons, which induce nuclear transitions and secondary electrons. Muons produced from the collision of cosmic rays with atmospheric nuclei are a significant source of background radiation at and below Earth's surface. The muon flux is measured by the coincidence of minimum ionization radiation loss in two plastic scintillator paddles. The spectrum of gamma ray photons is measured using sodium iodide based scintillators. These measurements will provide a characterization of the background and rates at the PTOLEMY site.

  1. Gamma heating measurements in a mixed radiation field

    SciTech Connect

    Chiu, H.K. (Illinois Univ., Urbana, IL (USA). Dept. of Nuclear Engineering); Bennett, E.F.; Micklich, B.J. (Argonne National Lab., IL (USA))

    1990-09-01

    Gamma hearing measurements have been made in a low-Z assembly irradiated with 14-MeV neutrons and (n,n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. The assembly is composed of 144 magnesium sleeves (5cm {times} 5cm {times} 60cm {times} 3 mm thick) filled with graphite to simulate a fusion blanket test module. Heating measurements were made in the mid-line of the assembly using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition (CBA) mode. The neutron induced atomic recoil signal was rejected by observing the signal rise-time differences inherent to radiations of different LET. The experiment was modelled using the one-dimensional radiation transport code ANISN/PC. The operating limits of this technique were identified by comparing measurements made at different positions in the assembly and then comparing these measurements to the calculated flux. 7 refs., 5 figs., 1 tab.

  2. IFN-{gamma}+ CD8+ T Lymphocytes: Possible Link Between Immune and Radiation Responses in Tumor-Relevant Hypoxia

    SciTech Connect

    De Ridder, Mark [Radiotherapie, Oncologisch Centrum, UZ Brussel, Brussels (Belgium); Cancer Research Unit, Vrije Universiteit Brussel, Brussels (Belgium)], E-mail: mark.deridder@uzbrussel.be; Jiang Heng; Esch, Gretel van; Law, Kalun; Monsaert, Christinne [Cancer Research Unit, Vrije Universiteit Brussel, Brussels (Belgium); Berge, Dirk L. van den; Verellen, Dirk; Verovski, Valeri N. [Radiotherapie, Oncologisch Centrum, UZ Brussel, Brussels (Belgium); Storme, Guy A. [Radiotherapie, Oncologisch Centrum, UZ Brussel, Brussels (Belgium); Cancer Research Unit, Vrije Universiteit Brussel, Brussels (Belgium)

    2008-07-01

    Activated T lymphocytes are known to kill tumor cells by triggering cytolytic mechanisms; however, their ability to enhance radiation responses remains unclear. This study examined the radiosensitizing potential of mouse CD8+ T cells, obtained by T-cell-tailored expansion and immunomagnetic purification. Activated CD8+ T cells displayed an interferon (IFN)-{gamma}+ phenotype and enhanced by 1.8-fold the radiosensitivity of EMT-6 tumor cells in 1% oxygen, which modeled tumor-relevant hypoxia. Radiosensitization was counteracted by neutralizing IFN-{gamma} or by blocking the inducible isoform of nitric oxide synthase, thus delineating the immune-tumor cell interaction through the IFN-{gamma} secretion pathway. Reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, and fluorescence-activated cell sorter data in agreement detected downregulation of the IFN-{gamma} gene by hypoxia, which caused IFN-{gamma} deficiency next to radioresistance. Therefore, immune and radiation responses are likely to be allied in the hypoxic tumor microenvironment, and CD8+ T cells may bridge immunostimulatory and radiosensitizing strategies.

  3. Radiation hardness of high resistivity magnetic Czochralski silicon detectors after gamma, neutron, and proton radiations

    Microsoft Academic Search

    Zheng Li; Jaakko Harkonen; Wei Chen; J. Kierstead; Panja Luukka; Eija Tuominen; Etuovine Tuovinen; Elea Verbitskaya; Vladimir Eremin

    2004-01-01

    High resistivity magnetic Czochralski Si detectors were irradiated with 60Co gamma rays, neutrons, and protons to various doses\\/fluences, along with control float zone Si detectors. 1) It has been found that for gamma radiation, magnetic Czochralski Si detectors behave similarly to the high-temperature, long-time (HTLT) oxygenated float zone Si detectors. There is no space charge sign inversion and there is

  4. Flavopiridol enhances human tumor cell radiosensitivity and prolongs expression of gammaH2AX foci.

    PubMed

    Camphausen, Kevin; Brady, Kristin J; Burgan, William E; Cerra, Michael A; Russell, Jeffery S; Bull, Elizabeth E A; Tofilon, Philip J

    2004-04-01

    Flavopiridol is a cyclin-dependent kinase (CDK) inhibitor, which has recently entered clinical trials. However, when administered as a single agent against solid tumors, the antitumor actions of flavopiridol have been primarily cytostatic. Given its reported effects on cell cycle regulation, transcription, and apoptosis, flavopiridol may also influence cellular radioresponse. Thus, to evaluate the potential for combining this cyclin-dependent kinase inhibitor with radiation as a cancer treatment strategy, we have investigated the effects of flavopiridol on the radiation sensitivity of two human prostate cancer cell lines (DU145 and PC3). The data presented here indicate that exposure to flavopiridol (60-90 nM) after irradiation enhanced the radiosensitivity of both DU145 and PC3 cells. This sensitization occurred in the absence of significant reductions in cell proliferation, retinoblastoma protein phosphorylation, or P-TEFb activity. Moreover, the post-irradiation addition of flavopiridol had no effect on radiation-induced apoptosis or the activation of the G2 cell cycle checkpoint. However, flavopiridol did modify the time course of gammaH2AX expression in irradiated cells. Whereas there was no significant difference in radiation-induced gammaH2AX foci at 6 h, at 24 h after irradiation, the number of cells expressing gammaH2AX foci was significantly greater in the flavopiridol-treated cells. These results indicate that flavopiridol can enhance radiosensitivity of human tumor cells and suggest that this effect may involve an inhibition of DNA repair. PMID:15078984

  5. Lightning flashes conducive to the production and escape of gamma radiation to space

    Microsoft Academic Search

    E. Williams; R. Boldi; J. Bór; G. Sátori; C. Price; E. Greenberg; Y. Takahashi; K. Yamamoto; Y. Matsudo; Y. Hobara; M. Hayakawa; T. Chronis; E. Anagnostou; D. M. Smith; L. Lopez

    2006-01-01

    Gamma radiation observed in space has been associated with lightning flashes in thunderstorms. These special flashes do not appear to be the large and energetic positive ground flashes that also produce sprites. Considerations of gamma ray attenuation in air indicate that such flashes may not produce gamma radiation at sufficient altitude to enable their escape to space. High-altitude intracloud lightning,

  6. Radiation metabolomics. 1. Identification of minimally invasive urine biomarkers for gamma-radiation exposure in mice.

    PubMed

    Tyburski, John B; Patterson, Andrew D; Krausz, Kristopher W; Slavík, Josef; Fornace, Albert J; Gonzalez, Frank J; Idle, Jeffrey R

    2008-07-01

    Gamma-radiation exposure has both short- and long-term adverse health effects. The threat of modern terrorism places human populations at risk for radiological exposures, yet current medical countermeasures to radiation exposure are limited. Here we describe metabolomics for gamma-radiation biodosimetry in a mouse model. Mice were gamma-irradiated at doses of 0, 3 and 8 Gy (2.57 Gy/min), and urine samples collected over the first 24 h after exposure were analyzed by ultra-performance liquid chromatography-time-of-flight mass spectrometry (UPLC-TOFMS). Multivariate data were analyzed by orthogonal partial least squares (OPLS). Both 3- and 8-Gy exposures yielded distinct urine metabolomic phenotypes. The top 22 ions for 3 and 8 Gy were analyzed further, including tandem mass spectrometric comparison with authentic standards, revealing that N-hexanoylglycine and beta-thymidine are urinary biomarkers of exposure to 3 and 8 Gy, 3-hydroxy-2-methylbenzoic acid 3-O-sulfate is elevated in urine of mice exposed to 3 but not 8 Gy, and taurine is elevated after 8 but not 3 Gy. Gene Expression Dynamics Inspector (GEDI) self-organizing maps showed clear dose-response relationships for subsets of the urine metabolome. This approach is useful for identifying mice exposed to gamma radiation and for developing metabolomic strategies for noninvasive radiation biodosimetry in humans. PMID:18582157

  7. [Early cell response to radiation].

    PubMed

    Le Péchoux, C; Deniaud-Alexandre, E; Ponette, V; Giocanti, N; Favaudon, V

    1997-01-01

    The early steps of cellular radiation response have been investigated using a linear electron accelerator operated in a split-dose mode, in such a way that the time intervals between pulse exposures to relativistic electrons ranged from fractions of a second to a few minutes. The initial dose brought about large, synchronous changes in radiation sensitivity and generated a tetraphasic, W-shaped time-dependent profile of cell survival upon the second radiation exposure. While this time-related process was observed in most cell lines investigated, its kinetic parameters varied significantly from one cell line to the other. The number of DNA strand breaks (neutral and alkaline DNA filter elution) and the level of apoptosis (gel electrophoresis and flow cytometry) induced at the different phases of the time-dependent profile showed no relationship with the W-effect. It is presently hypothesized that mechanisms involved in molecular recognition of radio-induced lesions and initiation of genomic instability play a major role in this effect. Whatever the mechanism involved, the split-dose irradiation in the range of seconds enables dissecting the early steps of radiation response. The relevance of the W-effect to radiation therapy and technical drawbacks are discussed. PMID:9587382

  8. The origin of the diffuse background gamma-radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations have now provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV. There is some evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation have been observed which provide evidence for its origin in nuclear processes in the early stages of the big-band cosmology and tie in these processes with galaxy fromation theory. A crucial test of the theory may lie in future observations of the background radiation in the 100 MeV to 100 GeV energy range which may be made with large orbiting spark-chamber satellite detectors. A discussion of the theoretical interpretations of present data, their connection with baryon symmetric cosmology and galaxy formation theory, and the need for future observations are given.

  9. The origin of the diffuse background gamma radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV, and evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation were observed which provide evidence for its origin in nuclear processes in the early stages of big-bang cosmology, and connect these processes with the galaxy formation theory. A test of the theory is in future observations of the background radiation in the 100 MeK to 100 GeV energy range which are made with large orbiting spark-chamber satellite detectors. The theoretical interpretations of present data, their connection with baryon-symmetric cosmology and galaxy formation theory, and the need for future observations are discussed.

  10. Solar cell radiation damage

    Microsoft Academic Search

    R. L. Crabb

    1994-01-01

    During the past 34 years, silicon or gallium arsenide solar cells have remained the main power source for nearly all spacecraft; power output levels having risen from a few milliwatts (Vanguard 1, 1958) to many kilowatts in the 1970s and 1980s (Skylab, 21 kW; MIR, 10 kW; Hubble Space Telescope, 5 kW). The steady technological progress made in improving solar

  11. Radiative decays of the Upsilon(1S) to gamma pi(0)pi(0), gamma eta eta and gamma pi(0)eta

    Microsoft Academic Search

    D. Besson; T. K. Pedlar; D. Cronin-Hennessy; K. Y. Gao; D. T. Gong; J. Hietala; Y. Kubota; T. Klein; B. W. Lang; R. Poling; A. W. Scott; A. Smith; S. Dobbs; Z. Metreveli; K. K. Seth; A. Tomaradze; P. Zweber; J. Ernst; K. Arms; H. Severini; S. A. Dytman; W. Love; S. Mehrabyan; J. A. Mueller; V. Savinov; Z. Li; A. Lopez; H. Mendez; J. Ramirez; G. S. Huang; D. H. Miller; V. Pavlunin; B. Sanghi; I. P. J. Shipsey; G. S. Adams; M. Anderson; J. P. Cummings; I. Danko; J. Napolitano; Q. He; H. Muramatsu; C. S. Park; E. H. Thorndike; T. E. Coan; Y. S. Gao; F. Liu; M. Artuso; C. Boulahouache; S. Blusk; J. Butt; J. Li; N. Menaa; S. Nisar; K. Randrianarivony; R. Redjimi; R. Sia; T. Skwarnicki; S. Stone; J. C. Wang; K. Zhang; S. E. Csorna; G. Bonvicini; D. Cinabro; M. Dubrovin; A. Lincoln; R. A. Briere; G. P. Chen; J. Chen; T. Ferguson; G. Tatishvili; H. Vogel; M. E. Watkins; J. L. Rosner; N. E. Adam; J. P. Alexander; K. Berkelman; D. G. Cassel; J. E. Duboscq; K. M. Ecklund; R. Ehrlich; L. Fields; R. S. Galik; L. Gibbons; R. Gray; S. W. Gray; D. L. Hartill; B. K. Heltsley; D. Hertz; C. D. Jones; J. Kandaswamy; D. L. Kreinick; V. E. Kuznetsov; H. Mahlke-Kruger; T. O. Meyer; P. U. E. Onyisi; J. R. Patterson; D. Peterson; E. A. Phillips; J. Pivarski; D. Riley; A. Ryd; A. J. Sadoff; H. Schwarthoff; X. Shi; S. Stroiney; W. M. Sun; T. Wilksen; M. Weinberger; S. B. Athar; P. Avery; L. Breva-Newell; R. Patel; V. Potlia; H. Stoeck; J. Yelton; P. Rubin; C. Cawlfield; B. I. Eisenstein; I. Karliner; D. Kim; N. Lowrey; P. Naik; C. Sedlack; M. Selen; E. J. White; J. Wiss; M. R. Shepherd; D. M. Asner; K. W. Edwards

    2007-01-01

    We report on a study of exclusive radiative decays of the Y(1S) resonance into the final states gamma pi(0)pi(0), gamma eta eta and gamma pi(0)eta, using 1.13 fb(-1) of e(+)e(-) annihilation data collected at root s=9.46 GeV with the CLEO III detector operating at the Cornell Electron Storage Ring. In the channel gamma pi(0)pi(0), we measure the branching ratio for

  12. Docosahexaenoic acid sensitizes Ramos cells to Gamma-irradiation-induced apoptosis through involvement of PPAR-? activation and NF-?B suppression

    Microsoft Academic Search

    Hamid Zand; Ali Rahimipour; Saideh Salimi; Sayed Mohammad Shafiee

    2008-01-01

    Gamma-irradiation (Gamma-IR) resistance is a character of many malignant cells that decreases the efficacy of radiotherapy.\\u000a Although ionizing radiation activates multiple cellular factors that vary depending on dose and tissue specificity, the activation\\u000a of nuclear factor-? B appears to be a well-conserved response in tumor cells exposed to Gamma-IR which can lead to the inhibition\\u000a of radiation-induced apoptosis. Thus, inhibition

  13. Gamma-ray pulsars: Radiation processes in the outer magnetosphere

    SciTech Connect

    Romani, R.W.

    1996-01-01

    The authors describe an emission model for gamma ray pulsars based on curvature radiation-reaction limited charges in the outer magnetosphere. They show how pair production on thermal surface flux can limit the acceleration zones. Estimates for the efficiency of GeV photon production eta gamma and the gamma-ray beaming fraction are derived, including their dependence on pulsar parameters. In general eta gamma increases with pulsar age, but is decreased for low magnetic fields and for small magnetic inclinations. They argue that this produces GeV pulse profiles, curvature spectra and detection statistics consistent with the observations. They also describe the optical through X-ray pulsar synchrotron spectrum and the spectral variations with pulsar phase. A test computation for Vela-like parameters reproduces phase-resolved GeV spectra consistent with those observed by EGRET. Finally they comment on very high energy pulsed emission and particle production and note extensions needed to allow a more complete pulsar model.

  14. Gamma-ray pulsars: Radiation processes in the outer magnetosphere

    NASA Technical Reports Server (NTRS)

    Romani, Roger W.

    1996-01-01

    We describe an emission model for gamma ray pulsars based on curvature radiation-reaction limited charges in the outer magnetosphere. We show how pair production on thermal surface flux can limit the acceleration zones. Estimates for the efficiency of GeV photon production eta gamma and the gamma-ray beaming fraction are derived, including their dependence on pulsar parameters. In general eta gamma increases with pulsar age, but is decreased for low magnetic fields and for small magnetic inclinations. We argue that this produces GeV pulse profiles, curvature spectra and detection statistics consistent with the observations. We also describe the optical through X-ray pulsar synchrotron spectrum and the spectral variations with pulsar phase. A test computation for Vela-like parameters reproduces phase-resolved GeV spectra consistent with those observed by EGRET. Finally we comment on very high energy pulsed emission and particle production and note extensions needed to allow a more complete pulsar model.

  15. Radiation sterilization of fluoroquinolones in solid state: Investigation of effect of gamma radiation and electron beam

    Microsoft Academic Search

    Babita K. Singh; Dilip V. Parwate; Indrani B. Dassarma; Sudhir K. Shukla

    2010-01-01

    The effect of gamma radiation from 60Co source and 2MeV electron beam was studied on two fluoroquinolone antibiotics viz norfloxacin and gatifloxacin in the solid state. The changes in reflectance spectrum, yellowness index, vibrational characteristics, thermal behavior, UV spectrum, chemical potency (HPLC) and microbiological potency were investigated. ESR measurement gave the number of free radical species formed and their population.

  16. EFFECTS OF GAMMA RADIATION ON ELECTROCHEMICAL PROPERTIES OF IONIC LIQUIDS

    SciTech Connect

    Visser, A; Nicholas Bridges, N; Thad Adams, T; John Mickalonis, J; Mark02 Williamson, M

    2009-04-21

    The electrochemical properties of ionic liquids (ILs) make them attractive for possible replacement of inorganic salts in high temperature molten salt electrochemical processing of nuclear fuel. To be a feasible replacement solvent, ILs need to be stable in moderate and high doses of radiation without adverse chemical and physical effects. Here, we exposed seven different ILs to a 1.2 MGy dose of gamma radiation to investigate their physical and chemical properties as they related to radiological stability. The azolium-based ILs experienced the greatest change in appearance, but these ILs were chemically more stable to gamma radiation than some of the other classes of ILs tested, due to the presence of aromatic electrons in the azolium ring. All the ILs exhibited a decrease in their conductivity and electrochemical window (at least 1.1 V), both of which could affect the utility of ILs in electrochemical processing. The concentration of the irradiation decomposition products was less than 3 mole %, with no impurities detectable using NMR techniques.

  17. Inhaled /sup 239/PuO/sub 2/ and/or total-body gamma radiation: Early mortality and morbidity in rats and dogs

    SciTech Connect

    Filipy, R.E.; Decker, J.R.; Lai, Y.L.; Lauhala, K.E.; Buschbom, R.L.; Hiastala, M.P.; McGee, D.R.; Park, J.F.; Kuffel, E.G.; Ragan, H.A.; Cannon, W.C.; Yaniv, S.S.; Scott, B.R.

    1988-08-01

    Rats and beagle dogs were given doses of /sup 60/Co gamma radiation and/or body burdens of /sup 239/PuO/sub 2/ within lethal ranges in an experiment to determine and compare morbidity and mortality responses of both species within 1 year after exposure. Radiation-induced morbidity was assessed by measuring changes in body weights, hematologic parameters, and pulmonary-function parameters. Gamma radiation caused transient morbidity, reflected by immediately depressed blood cell concentrations and by long-term loss of body weight and diminished pulmonary function in animals of both species that survived the acute gamma radiation syndrome. Inhaled plutonium caused a loss of body weight and diminished pulmonary function in both species, but its only effect on blood cell concentrations was lymphocytopenia in dogs. Combined gamma irradiation and plutonium lung burdens were synergistic, in that animals receiving both radiation insults had higher morbidity and mortality rates than would be predicted based on the effect of either kind of radiation alone. Plutonium lung burdens enhanced the effect of gamma radiation in rats within the first 30 days of exposure, and gamma radiation enhanced the long-term effect of plutonium lung burdens in both species. Rats were less sensitive to both kinds of radiation, whether administered alone or in combination. 71 refs., 105 figs., 48 tabs.

  18. Predicted solar cell edge radiation effects

    Microsoft Academic Search

    Markland T. Gates

    1993-01-01

    The Advanced Solar Cell Orbital Test (ASCOT) will test six types of solar cells in a high energy proton environment. During the design of the experiment a question was raised about the effects of proton radiation incident on the edge of the solar cells and whether edge radiation shielding was required. Historical geosynchronous data indicated that edge radiation damage is

  19. Characterization of an Escherichia coli mutant (radB101) sensitive to. gamma. and uv radiation, and methyl methanesulfonate

    Microsoft Academic Search

    N. J. Sargentini; K. C. Smith

    1983-01-01

    After N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Escherichia coli K-12 (xthA14), an X-ray-sensitive mutant was isolated. This sensitivity is due to a mutation, radB101, which is located at 56.5 min on the E.coli K-12 linkage map. The radB101 mutation sensitized wild-type cells to ..gamma.. and uv radiation, and to methyl methanesulfonate. When known DNA repair-deficient mutants were ranked for their ..gamma..-radiation sensitivity relative

  20. Natural Radiation from Soil using Gamma-Ray Spectrometry

    SciTech Connect

    Silveira, M. A. G.; Moreira, R. H.; Paula, A. L. C. de [Centro Universitario da FEI, Sao Bernardo do Campo, Sao Paulo (Brazil); Medina, N. H. [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil)

    2009-06-03

    We have studied the distribution of natural radioactivity in the soil of Interlagos, in Sao Paulo city and Billings Reservoir, in Sao Bernardo do Campo, Sao Paulo, Brazil. The main contribution of the effective radiation dose is due to the elements of the {sup 238}Th decay series, with smaller contributions from {sup 40}K and the elements of the series of {sup 238}U. The results indicate the dose in all of the studied areas is around the average international dose due to external exposure to gamma rays (0.48 mSv/yr) proceeding from natural terrestrial elements.

  1. Effect of gamma radiation on selected functional and physical properties of liquid egg white 

    E-print Network

    Ball, Hershell Ray

    1966-01-01

    temperature of the freezer. kfter preparation, the samples were radiated using the gamma source of the Nuclear Science Center, Texas 0, i M University. 4, constant dose rate of 600 rad. per minute of gamma radiation from a Co source was employed...EFFECT OF GAMMA RADIATION ON SELECTED FUNCTIONAL AND PHYSICAL PROPERTIES OF LIQUID EGG WHITE A Thesis By Hershell Ray Ball, Jr. Approved as to style and content by) (Chairman of Committee) ead of Department) (Me mba (Member) ( ber) ~Ja...

  2. Enhancement of natural background gamma-radiation dose around uranium microparticles in the human body

    PubMed Central

    Pattison, John E.; Hugtenburg, Richard P.; Green, Stuart

    2010-01-01

    Ongoing controversy surrounds the adverse health effects of the use of depleted uranium (DU) munitions. The biological effects of gamma-radiation arise from the direct or indirect interaction between secondary electrons and the DNA of living cells. The probability of the absorption of X-rays and gamma-rays with energies below about 200 keV by particles of high atomic number is proportional to the third to fourth power of the atomic number. In such a case, the more heavily ionizing low-energy recoil electrons are preferentially produced; these cause dose enhancement in the immediate vicinity of the particles. It has been claimed that upon exposure to naturally occurring background gamma-radiation, particles of DU in the human body would produce dose enhancement by a factor of 500–1000, thereby contributing a significant radiation dose in addition to the dose received from the inherent radioactivity of the DU. In this study, we used the Monte Carlo code EGSnrc to accurately estimate the likely maximum dose enhancement arising from the presence of micrometre-sized uranium particles in the body. We found that although the dose enhancement is significant, of the order of 1–10, it is considerably smaller than that suggested previously. PMID:19776147

  3. Southern analysis of genomic alterations in gamma-ray-induced aprt- hamster cell mutants

    SciTech Connect

    Grosovsky, A.J.; Drobetsky, E.A.; deJong, P.J.; Glickman, B.W.

    1986-06-01

    The role of genomic alterations in mutagenesis induced by ionizing radiation has been the subject of considerable speculation. By Southern blotting analysis we show here that 9 of 55 (approximately 1/6) gamma-ray-induced mutants at the adenine phosphoribosyl transferase (aprt) locus of Chinese hamster ovary (CHO) cells have a detectable genomic rearrangement. These fall into two classes: intragenic deletions and chromosomal rearrangements. In contrast, no major genomic alterations were detected among 67 spontaneous mutants, although two restriction site loss events were observed. Three gamma-ray-induced mutants were found to be intragenic deletions; all may have identical break-points. The remaining six gamma-ray-induced mutants demonstrating a genomic alteration appear to be the result of chromosomal rearrangements, possibly translocation or inversion events. None of the remaining gamma-ray-induced mutants showed any observable alteration in blotting pattern indicating a substantial role for point mutation in gamma-ray-induced mutagenesis at the aprt locus.

  4. Effect of Gamma radiation on microbial population of natural casings

    NASA Astrophysics Data System (ADS)

    Trigo, M. J.; Fraqueza, M. J.

    1998-06-01

    The high microbial load of fresh and dry natural casings increases the risk of meat product contamination with pathogenic microorganisms, agents of foodborn diseases. The aim of this work is to evaluate the killing effect of gamma radiation of the resident microbial population of pork and beef casings, to improve their hygiene and safety. Portions of fresh pork (small intestines and colon) and dry beef casings were irradiated in a Cobalt 60 source with with absorbed doses of 1,2,5 and 10 kGy. The D 10 values of total aerobic microorganisms in the pork casings were 1.65 kGy for colon and 1.54 kGy for small intestine. The D 10 value found in beef dry casings (small intestine) was 10.17 kGy. Radurization with 5 kGy was able to reduce, at least, 6 logs the coliform bacteria in pork casings. The killing effect over faecal Streptococci was 4 logs for pork fresh casings and 2 logs for beef dry casings. Gamma radiation with 5 kGy proved to be a convenient method to reduce substantially the microbial population of pork fresh casings. Otherwise, the microbial population of beef dry casings still resisted to 10 kGy.

  5. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    History of GaAs solar cell development is provided. Photovoltaic equations are described along with instrumentation techniques for measuring solar cells. Radiation effects in solar cells, electrical performance, and spacecraft flight data for solar cells are discussed. The space radiation environment and solar array degradation calculations are addressed.

  6. Modeling radiation-induced cell cycle delays

    Microsoft Academic Search

    Anna Ochab-Marcinek; Ewa Gudowska-Nowak; Elena Nasonova; Sylvia Ritter

    2009-01-01

    Ionizing radiation is known to delay the cell cycle progression. In particular after particle exposure significant delays\\u000a have been observed and it has been shown that the extent of delay affects the expression of damage, such as chromosome aberrations.\\u000a Thus, to predict how cells respond to ionizing radiation and to derive reliable estimates of radiation risks, information\\u000a about radiation-induced cell

  7. Performance of radiation survey meters in X- and gamma-radiation fields.

    PubMed

    Ceklic, Sandra; Arandjic, Danijela; Zivanovic, Milos; Ciraj-Bjelac, Olivera; Lazarevic, Djordje

    2014-11-01

    The aim of this work was to investigate the different types of radiation detectors commonly used for radiation protection purposes as survey meters. The study was performed on survey meters that use different detectors as ionisation chamber, Geiger Mueller (GM) counter and scintillation detector. For each survey meter, energy dependence and angular response in X- and gamma-radiation fields was tested. The following commercially available survey meters were investigated: ionisation chambers Victoreen 451P, Babyline 31 and VA-J-15A, Geiger counter MRK-M87, 6150 AD6 and FAG FH 40F2 and scintillation counter 6150 ADB. As a source of gamma radiation, (137)Cs and (60)Co were used whereas X-ray radiation fields were generated using an X-ray unit. The radiation characteristics of the survey meters were mostly in compliance with references estimated by standard IEC 1017-2. However, some of them showed larger deviation at lower energies. GM counters exhibit strong energy dependence for low-energy photons. PMID:25063785

  8. Delayed gamma radiation from lightning induced nuclear reactions

    NASA Astrophysics Data System (ADS)

    Greenfield, M. B.; Sakuma, K.; Ikeda, Y.; Kubo, K.

    2004-03-01

    An increase in atmospheric gamma radiation observed with NaI and Ge detectors positioned about 15 m above ground was observed following natural lightning near Tokyo, Japan [1]. Background subtracted gamma ray rates GRR following numerous lightning strokes observed since 2001 persisted for a few hours and subsequently decayed with a half-life of about 50 minutes. Using a 3x3 Ge detector, with 2 KeV resolution, positioned about 2 m from one of the NaI detectors increases in GRR were observed minutes after the onset of lightning with a delayed 50 min exponential decay. Although most of the increase in activity occured at less than a few 100 KeV, on July 11, 2003 a 1267 +/-2 KeV line was observed. Although the statistics of this event were poor, the appearance of this line with an exponential decay of 50 min half-life suggests the possibility that it may be due to 39Cl (1267 MeV; half-life = 55.5 min) via the 40Ar(gamma,p)39Cl, 40Ar(p,2p)39Cl and/or 40Ar(n,d)39Cl reactions. Observations of > 10 MeV gamma rays observed in NaI detectors within 10s of meters from and coincident with rocket-triggered lightning at the International Center for Lightning Research and Testing suggest that charged particles accelerated in intense electric fields associated with lightning give rise to photons with sufficient energy to initiate nuclear reactions [2]. Further work to explain the cause of this anomalous activity is underway using natural and triggered lightning. 1. M. B. Greenfield et al., Journal of Applied Physics 93 no. 3 (2003) pp 1839-184. 2. J. R. Dwyer et al., Science 299, (2003), pp 694-697 and recent communications

  9. Determining the Impact of Concrete Roadways on Gamma Ray Background Readings for Radiation Portal Monitoring Systems 

    E-print Network

    Ryan, Christopher Michael

    2012-07-16

    country of origin. To combat the threat of nuclear trafficking, radiation portal monitors (RPMs) are deployed around the world to intercept illicit material while in transit by passively detecting gamma and neutron radiation. Portal monitors in some...

  10. Comparative toxicity and micronuclei formation in Tribolium castaneum, Callosobruchus maculatus and Sitophilus oryzae exposed to high doses of gamma radiation.

    PubMed

    Ahmadi, Mehrdad; Mozdarani, Hossein; Abd-Alla, Adly M M

    2015-07-01

    The effects of gamma radiation on mortality and micronucleus formation in Tribolium castaneum Herbst, Callosobruchus maculatus (F.) and Sitophilus oryzae (L.) genital cells were evaluated. Two groups of healthy and active adult insects 1-3 and 8-10 days old were irradiated with various doses (50-200Gy) gamma ray. Seven days post-irradiation; mortality rates and micronucleus formation were assessed in genital cells of the irradiated insects. The results show that with increasing gamma doses, the mortality rate of each species increased and T. castaneum and S. oryzae showed the low and high sensitivity respectively. It was shown that the micronucleus appearance in the tested insects had correlation with amount and intensity of radiation doses. Moreover our results indicate different levels in the genotoxicity of gamma radiation among the insects' genital cells under study. The frequency of micronuclei in genital cells of 1-3 days old insects exposed to 50 and 200Gy were 12.6 and 38.8Mn/1000 cells in T. castaneum, 20.8 and 46.8Mn/1000 cells in C. maculatus and 16.8 and 57.2Mn/1000 cells in S. oryzae respectively. A high sensitivity of the genital cells to irradiation exposure was seen in S. oryzae correlated with its high mortality rate compared with the other two species. These results might be indicative of inflicting chromosomal damage expressed as micronucleus in high mortality rates observed in the pest population; an indication of genotoxic effects of radiation on the studied species. PMID:25898238

  11. Quantum mechanical model for nuclear-resonant scattering of gamma radiation

    Microsoft Academic Search

    Gilbert R. Hoy

    1997-01-01

    A one-dimensional quantum mechanical model for nuclear-resonant scattering of gamma radiation from matter is developed assuming the source radiation is gamma decay. A closed-form, finite-sum solution for the radiated intensity is obtained by restricting the calculation to coherent forward scattering. The solution provides a unified microscopic picture of nuclear-resonant scattering processes in which the radiation undergoes sequential scattering from one

  12. Cytoskeletal and functional changes in bioreactor assembled thyroid tissue organoids exposed to gamma radiation

    NASA Technical Reports Server (NTRS)

    Green, Lora M.; Patel, Zarana; Murray, Deborah K.; Rightnar, Steven; Burell, Cheryl G.; Gridley, Daila S.; Nelson, Gregory A.

    2002-01-01

    Fischer rat thyroid cells were grown under low-shear stress in a bioreactor to a stage of organization composed of integrated follicles resembling small thyroid glands prior to exposure to 3 Gray-gamma radiation. Bioreactor tissues and controls (both irradiated and non-irradiated) were harvested at 24, 48, 96 and 144 hours post-exposure. Tissue samples were fixed and fluorescently labeled for actin and microtubules. Tissues were assessed for changes in cytoskeletal components induced by radiation and quantified by laser scanning cytometry. ELISA's were used to quantify transforming growth factor-beta and thyroxin released from cells to the culture supernatant. Tissue architecture was disrupted by exposure to radiation with the structural organization of actin and loss of follicular content the most obviously affected. With time post-irradiation the actin appeared disordered and the levels of fluorescence associated with filamentous-actin and microtubules cycled in the tissue analogs, but not in the flask-grown cultures. Active transforming growth factor-beta was higher in supernatants from the irradiated bioreactor tissue. Thyroxin release paralleled cell survival in the bioreactors and control cultures. Thus, the engineered tissue responses to radiation differed from those of conventional tissue culture making it a potentially better mimic of the in vivo situation.

  13. Preparation of polyester\\/gypsum\\/composite using gamma radiation, and its radiation stability

    Microsoft Academic Search

    Zaki Ajji

    2005-01-01

    Composites based on pure gypsum and polyester–styrene resin have been prepared using various doses of gamma radiation. Some physical properties of the prepared composites and the influence of irradiation dose on it have been studied as: compression strength, hardness, thermal decomposition temperature in nitrogen or oxygen, and the change in weight in aqueous solutions with different pH values.The glass transition

  14. Evaluation of the effects of paederus beetle extract and gamma irradiation on HeLa cells

    PubMed Central

    Samani, Fariba; Monfared, Ali Shabestani; Zabihi, Ebrahim; Khafri, Soraya; Karimi, Maesoumeh; Akhavan Niaki, Haleh

    2014-01-01

    Objective(s): Cervical cancer is a malignancy that is the second most common cause of death from cancer in women throughout the world. Paederus beetle (Paederus fuscipes) extract (PBE), contains bioactive compounds such as pederine which has cytotoxic properties and blocks DNA and protein synthesis at very low concentrations. In this investigation we tried to determine the effects co-treatment with PBE and gamma irradiation on HeLa cells. Materials and Methods: The viability of the cells was measured by two methods: MTT and Colony assay. Results: We found that supplementing gamma irradiation therapy with PBE does not increase cell death and it might even interfere with its cytotoxicty at the concentrations below 0.1 ng/ml and the viability for irradiation vs irradiation + PBE was 37%: 60%. Conclusion: This finding might be due to radioprotective effects of the very low doses of PBE against gamma radiation. PMID:24904724

  15. Two-year follow-up after intracoronary gamma radiation therapy

    Microsoft Academic Search

    José A Condado; Ron Waksman; Carlos Calderas; Jorge Saucedo; Alexandra Lansky

    1999-01-01

    Background. Neointimal hyperplasia and unfavorable remodeling have been demonstrated to be the major limitation to endovascular revascularization procedures. Intracoronary gamma radiation therapy has been shown to reduce the restenosis index. However, the late effects of these novel procedures are unknown.Materials and Methods. To evaluate the long-term effects on clinical and angiographic outcome of endovascular gamma radiation therapy following percutaneous transluminal

  16. Neutron and gamma radiation shielding material, structure, and process of making structure

    DOEpatents

    Hondorp, Hugh L. (Princeton Junction, NJ)

    1984-01-01

    The present invention is directed to a novel neutron and gamma radiation elding material consisting of 95 to 97 percent by weight SiO.sub.2 and 5 to 3 percent by weight sodium silicate. In addition, the method of using this composition to provide a continuous neutron and gamma radiation shielding structure is disclosed.

  17. Effect of acute gamma radiation on some physiological features of lichens

    Microsoft Academic Search

    M. G. Nifontova; A. P. Ravinskaya; I. A. Shapiro

    1995-01-01

    The influence of acute gamma radiation on four physiological characteristics of lichens was investigated. Membrane permeability in irradiated thalli of Cladonia arbuscula, Cetraria islandica and Hypogymnia physodes increased considerably compared to controls. The nitrogen content in Peltigera aphthosa appeared to be stable to acute gamma radiation. Up to 1000 Gy there was no essential decrease in respiration intensity in H.

  18. In situ gamma-ray spectrometry: A tutorial for environmental radiation scientists

    Microsoft Academic Search

    K. M. Miller; P. Shebell

    1993-01-01

    This tutorial is intended for those in the environmental field who perform assessments in areas where there is radioactive contamination in the surface soil. Techniques will be introduced for performing on-site quantitative measurements of gamma radiation in the environment using high resolution germanium detectors. A basic understanding of ionizing radiation principles is assumed; however, a detailed knowledge of gamma spectrometry

  19. Consequences of Lethal-Whole-Body Gamma Radiation and Possible Ameliorative Role of Melatonin

    PubMed Central

    Mihandoost, Ehsan; Shirazi, Alireza; Mahdavi, Seied Rabie; Aliasgharzadeh, Akbar

    2014-01-01

    Gamma radiation induces the generation of free radicals, leading to serious cellular damages in biological systems. Radioprotectors act as prophylactic agents that are administered to shield normal cells and tissues from the deleterious effects of radiation. Melatonin synergistically acts as an immune-stimulator and antioxidant. We investigated the possible radioprotective role of melatonin (100?mg/kg i.p.) against lethal-whole-body radiation- (10?Gy) induced sickness, body weight loss, and mortality in rats. Results of the present study suggest that exposure to lethal-whole-body radiation incurred mortality, body weight loss, and apoptosis and it also depleted the immunity and the antioxidant status of the rats. Our results show that melatonin pretreatment provides protection against radiation induced mortality, oxidative stress, and immune-suppression. The melatonin pretreated irradiated rats showed less change in body weight as compared to radiation only group. On the other hand, melatonin appeared to have another radioprotective role, suggesting that melatonin may reduce apoptosis through a caspase-3-mediated pathway by blocking caspase-3 activity. PMID:25431791

  20. Consequences of lethal-whole-body gamma radiation and possible ameliorative role of melatonin.

    PubMed

    Mihandoost, Ehsan; Shirazi, Alireza; Mahdavi, Seied Rabie; Aliasgharzadeh, Akbar

    2014-01-01

    Gamma radiation induces the generation of free radicals, leading to serious cellular damages in biological systems. Radioprotectors act as prophylactic agents that are administered to shield normal cells and tissues from the deleterious effects of radiation. Melatonin synergistically acts as an immune-stimulator and antioxidant. We investigated the possible radioprotective role of melatonin (100 mg/kg i.p.) against lethal-whole-body radiation- (10 Gy) induced sickness, body weight loss, and mortality in rats. Results of the present study suggest that exposure to lethal-whole-body radiation incurred mortality, body weight loss, and apoptosis and it also depleted the immunity and the antioxidant status of the rats. Our results show that melatonin pretreatment provides protection against radiation induced mortality, oxidative stress, and immune-suppression. The melatonin pretreated irradiated rats showed less change in body weight as compared to radiation only group. On the other hand, melatonin appeared to have another radioprotective role, suggesting that melatonin may reduce apoptosis through a caspase-3-mediated pathway by blocking caspase-3 activity. PMID:25431791

  1. Interleukin-12 activates NK cells for IFN-gamma-dependent and NKT cells for IFN-gamma-independent antimetastatic activity.

    PubMed

    Hafner, M; Falk, W; Echtenacher, B; Männel, D N

    1999-12-01

    Mechanisms involved in the antimetastatic effect of IL-12 were analyzed in a mouse model of experimental metastasis with either syngeneic fibrosarcoma cells colonizing the lungs or syngeneic B cell lymphoma cells colonizing the liver. IL-12 pretreatment effectively reduced the number of tumor colonies in both systems. This effect was already manifest 24 hours after tumor cell injection, indicating a T and B cell-independent mechanism. Therefore, the involvement of NK and alphabetaNKT cells was investigated using mice with defective NK and alphabetaNKT cell functions. Mice with impaired NK functions due to NK cell depletion, were less responsive to the antimetastatic IL-12 effect. IL-12 treatment failed to inhibit metastasis in beta2-microglobulin-deficient mice which lack alphabetaNKT cells in addition to having impaired NK cell activity, thus, demonstrating the functional importance of IL-12-activated NK and alphabetaNKT cells. While the IL-12-induced antimetastatic effect of NK cells was dependent on IFN-gamma action, IL-12 activation of alphabetaNKT cells did not involve IFN-gamma. The neutralization of IFN-gamma or the use of IFN-gamma receptor-deficient mice did not alter the IL-12-induced effect in the absence of NK cells. Activation of effector cells of the innate immune system, such as NK and alphabetaNKT cells, seems to be the main mechanism for the antimetastatic effect of IL-12. PMID:10586121

  2. Lightning flashes conducive to the production and escape of gamma radiation to space

    NASA Astrophysics Data System (ADS)

    Williams, E.; Boldi, R.; Bór, J.; Sátori, G.; Price, C.; Greenberg, E.; Takahashi, Y.; Yamamoto, K.; Matsudo, Y.; Hobara, Y.; Hayakawa, M.; Chronis, T.; Anagnostou, E.; Smith, D. M.; Lopez, L.

    2006-08-01

    Gamma radiation observed in space has been associated with lightning flashes in thunderstorms. These special flashes do not appear to be the large and energetic positive ground flashes that also produce sprites. Considerations of gamma ray attenuation in air indicate that such flashes may not produce gamma radiation at sufficient altitude to enable their escape to space. High-altitude intracloud lightning, most prevalent in the tropics where the tropopause is also high, may be a necessary source.

  3. Evaluation of gamma radiation shielding for nuclear waste shipping casks

    SciTech Connect

    Liu, Y.Y.; Carlson, R.D. [Argonne National Lab., IL (United States). Energy Technology Div.; Primeau, S.J. [Eagle Research Group, Inc., Germantown, MD (United States); Wangler, M.E. [Dept. of Energy, Germantown, MD (United States). Office of Transportation, Emergency Management and Analytical Services

    1998-05-01

    A method has been developed for evaluating gamma radiation shielding of shipping casks that are used to transport nuclear waste with ill-defined radionuclide contents. The method is based on calculations that establish individual limits for a comprehensive list of radionuclides in the waste, assuming that each radionuclide is uniformly distributed in a volumetric source in the cask. For multiple radionuclide mixtures, a linear fraction rule is used to restrict the total amount of radionuclides such that the sum of the fractions does not exceed 1. As long as the radionuclide limits and the linear fraction rule are followed, it can be shown that the regulatory dose rate requirements for a cask will be satisfied under normal conditions of transport and in a hypothetical accident during which the shielding thickness of the cask has been reduced by 40%.

  4. Effect of gamma radiation on native endolithic microorganisms from a radioactive waste deposit site.

    PubMed

    Pitonzo, B J; Amy, P S; Rudin, M

    1999-07-01

    A time-course experiment was conducted to evaluate the effects of gamma radiation on the indigenous microbiota present in rock obtained from Yucca Mountain, Nevada Test Site. Microcosms were constructed by placing pulverized Yucca Mountain rock in polystyrene cylinders. Continuous exposure (96 h) at a dose rate of 1.63 Gy/min was used to mimic the near-field environment surrounding waste canisters. The expected maximum surface dose rate from one unbreached canister designed to contain spent nuclear fuels is 0.06 Gy/min. Considering the current repository packing design, multiple canisters within one vault, the cumulative dose rate may well approach that used in this experiment. The microbial communities were characterized after receiving cumulative doses of 0, 0.098, 0. 58, 2.33, 4.67, 7.01 and 9.34 kGy. Radiation-resistant microorganisms in the pulverized rock became viable but nonculturable (VBNC) after a cumulative dose of 2.33 kGy. VBNC microorganisms lose the ability to grow on media on which they have routinely been cultured in response to the environmental stress imposed (i.e. radiation) but can be detected throughout the time course using direct fluorescence microscopy techniques. Two representative exopolysaccharide-producing isolates from Yucca Mountain were exposed to the same radiation regimen in sand microcosms. One isolate was much more radiation-resistant than the other, but both had greater resistance than the general microbial community based on culturable counts. However, when respiring cell counts (VBNC) were compared after irradiation, the results would indicate much more radiation resistance of the individual isolates and the microbial community in general. These results have significant implications for underground storage of nuclear waste as they indicate that indigenous microorganisms are capable of surviving gamma irradiation in a VBNC state. PMID:10381842

  5. Phoswich scintillator for proton and gamma radiation of high energy

    NASA Astrophysics Data System (ADS)

    Tengblad, O.; Nilsson, T.; Borge, M. J. G.; Briz, J. A.; Carmona-Gallardo, M.; Cruz, C.; Gugliermina, V.; Nácher, E.; Perea, A.; del Rio, J. Sanchez; Nieves, M. Turrion; Johansson, H. T.; Bergström, J.; Blomberg, E.; Bülling, A.; Gallneby, E.; Hagdahl, J.; Jansson, L.; Jareteg, K.; Masgren, R.; Nordström, M.; Risting, G.; Shojaee, S.; Wittler, H.

    2011-11-01

    We present here a Phoswich scintillator design to achieve both high resolution gamma ray detection, and good efficiency for high energy protons. There are recent developments of new high resolution scintillator materials. Especially the LaBr3(Ce) and LaCl3(Ce) crystals have very good energy resolution in the order of 3% for 662 keV gamma radiation. In addition, these materials exhibit a very good light output (63 and 32 photons/keV respectively). A demonstrator detector in the form of an Al cylinder of 24 mm diameter and a total length of 80 mm with 2 mm wall thickness, containing a LaBr3(Ce) crystal of 20 mm diameter and 30 mm length directly coupled to a LaCl3(Ce) crystal of 50 mm length, and closed with a glass window of 5 mm, was delivered by Saint Gobain. To the glass window a Hamamatsu R5380 Photomultiplier tube (PMT) was coupled using silicon optical grease.

  6. \\Gamma\\Gamma \\Gamma\\Gamma

    E-print Network

    Laske, Gabi

    \\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma yyy yyy \\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma@@####\\Gamma\\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma @@@ @@@ ### ### ### ### \\Gamma\\Gamma\\Gamma \\Gamma\\Gamma\\Gamma yyy

  7. Gamma radiation effects on polydimethylsiloxane rubber foams under different radiation conditions

    NASA Astrophysics Data System (ADS)

    Sui, H. L.; Liu, X. Y.; Zhong, F. C.; Li, X. Y.; Wang, L.; Ju, X.

    2013-07-01

    Polydimethylsiloxane rubber foams were irradiated by gamma ray under different radiation conditions designed by orthogonal design method. Compression set measurement, infrared attenuated total reflectance spectroscopy (ATR) and X-ray induced photoelectron spectroscopy (XPS) were used. Three aging factors' influence effects on the mechanical property and chemical structure were studied. It was found that among the three factors and the chosen levels, both properties were affected most by radiation dose, while radiation dose rate had no obvious influence on both properties. The stiffening of the rubber foams was caused by cross-linking reactions in the Si-CH3. At the same radiation dose, the rigidity of the foams irradiated in air was lower than that in nitrogen. When polydimethylsiloxane was irradiated at a high dose in sealed nitrogen atmosphere, carbon element distribution would be changed. Hydrocarbons produced by gamma ray in the sealed tube would make the carbon content in the skin-deep higher than that in the middle, which indicated that polydimethylsiloxane rubber foams storing in a sealed atmosphere filled with enough hydrocarbons should be helpful to extend the service life.

  8. Intestinal endocrine cells in radiation enteritis

    SciTech Connect

    Pietroletti, R.; Blaauwgeers, J.L.; Taat, C.W.; Simi, M.; Brummelkamp, W.H.; Becker, A.E. (Academic Medical Centre, Amsterdam (Netherlands))

    1989-08-01

    In this study, the intestinal endocrine cells were investigated in 13 surgical specimens affected by radiation enteritis. Endocrine cells were studied by means of Grimelius' silver staining and immunostaining for chromogranin, a general marker of endocrine cells. Positively stained cells were quantified by counting their number per unit length of muscularis mucosa. Results in radiation enteritis were compared with matched control specimens by using Student's t test. Chromogranin immunostaining showed a statistically significant increase of endocrine cells in radiation enteritis specimens compared with controls both in small and large intestine (ileum, 67.5 +/- 23.5 cells per unit length of muscularis mucosa in radiation enteritis versus 17.0 +/- 6.1 in controls; colon, 40.9 +/- 13.7 cells per unit length of muscularis mucosa in radiation enteritis versus 9.5 +/- 4.1 in controls--p less than 0.005 in both instances). Increase of endocrine cells was demonstrated also by Grimelius' staining; however, without reaching statistical significance. It is not clear whether or not the increase of endocrine cells in radiation enteritis reported in this study is caused by a hyperplastic response or by a sparing phenomenon. We should consider that increased endocrine cells, when abnormally secreting their products, may be involved in some of the clinical features of radiation enteropathy. In addition, as intestinal endocrine cells produce trophic substances to the intestine, their increase could be responsible for the raised risk of developing carcinoma of the intestine in long standing radiation enteritis.

  9. Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonist, independently of PPAR{gamma} in human glioma cells

    SciTech Connect

    Lee, Myoung Woo; Kim, Dae Seong; Kim, Hye Ryung; Kim, Hye Jin; Yang, Jin Mo; Ryu, Somi; Noh, Yoo Hun; Lee, Soo Hyun; Son, Meong Hi; Jung, Hye Lim; Yoo, Keon Hee [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)] [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Koo, Hong Hoe, E-mail: hhkoo@skku.edu [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Sung, Ki Woong, E-mail: kwsped@skku.edu [Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Greater than 30 {mu}M ciglitazone induces cell death in glioma cells. Black-Right-Pointing-Pointer Cell death by ciglitazone is independent of PPAR{gamma} in glioma cells. Black-Right-Pointing-Pointer CGZ induces cell death by the loss of MMP via decreased Akt. -- Abstract: Peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPAR{gamma} in CGZ-induced cell death was examined. At concentrations of greater than 30 {mu}M, CGZ, a synthetic PPAR{gamma} agonist, activated caspase-3 and induced apoptosis in T98G cells. Treatment of T98G cells with less than 30 {mu}M CGZ effectively induced cell death after pretreatment with 30 {mu}M of the PPAR{gamma} antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPAR{gamma} was down-regulated cells by siRNA, lower concentrations of CGZ (<30 {mu}M) were sufficient to induce cell death, although higher concentrations of CGZ ( Greater-Than-Or-Slanted-Equal-To 30 {mu}M) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPAR{gamma}. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPAR{gamma} in glioma cells, by down-regulating Akt activity and inducing MMP collapse.

  10. Rapid and transient activation of gamma/delta T cells to interferon gamma production, NK cell-like killing and antigen processing during acute virus infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gamma/delta T cells are the majority peripheral blood T cells in young cattle. The role of gamma/delta T cells in innate responses against infection with foot-and-mouth disease virus (FMDV) was analyzed on 5 consecutive days following infection. Before infection, bovine gamma/delta T cells expressed...

  11. Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway.

    PubMed

    You, Y; Wen, R; Pathak, R; Li, A; Li, W; St Clair, D; Hauer-Jensen, M; Zhou, D; Liang, Y

    2014-01-01

    Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy. PMID:25341047

  12. Solar cell radiation handbook. [Degradation of solar cells in space radiation environment

    Microsoft Academic Search

    H. Y. Tada; J. R. Jr. Carter

    1977-01-01

    The purpose of this document is to detail a method of predicting the degradation of a solar array in a space radiation environment. The text contains a discussion of solar cell technology which emphasizes the cell parameters which degrade in a radiation environment. The experimental techniques used in the evaluation of radiation effects are discussed. The theoretical aspects of radiation

  13. Progenitors Mobilized by Gamma-Tocotrienol as an Effective Radiation Countermeasure

    PubMed Central

    Singh, Vijay K.; Wise, Stephen Y.; Fatanmi, Oluseyi O.; Scott, Jessica; Romaine, Patricia L. P.; Newman, Victoria L.; Verma, Amit; Elliott, Thomas B.; Seed, Thomas M.

    2014-01-01

    The purpose of this study was to elucidate the role of gamma-tocotrienol (GT3)-mobilized progenitors in mitigating damage to mice exposed to a supralethal dose of cobalt-60 gamma-radiation. CD2F1 mice were transfused 24 h post-irradiation with whole blood or isolated peripheral blood mononuclear cells (PBMC) from donors that had received GT3 72 h prior to blood collection and recipient mice were monitored for 30 days. To understand the role of GT3-induced granulocyte colony-stimulating factor (G-CSF) in mobilizing progenitors, donor mice were administered a neutralizing antibody specific to G-CSF or its isotype before blood collection. Bacterial translocation from gut to heart, spleen and liver of irradiated recipient mice was evaluated by bacterial culture on enriched and selective agar media. Endotoxin in serum samples also was measured. We also analyzed the colony-forming units in the spleens of irradiated mice. Our results demonstrate that whole blood or PBMC from GT3-administered mice mitigated radiation injury when administered 24 h post-irradiation. Furthermore, administration of a G-CSF antibody to GT3-injected mice abrogated the efficacy of blood or PBMC obtained from such donors. Additionally, GT3-mobilized PBMC inhibited the translocation of intestinal bacteria to the heart, spleen, and liver, and increased colony forming unit-spleen (CFU-S) numbers in irradiated mice. Our data suggests that GT3 induces G-CSF, which mobilizes progenitors and these progenitors mitigate radiation injury in recipient mice. This approach using mobilized progenitor cells from GT3-injected donors could be a potential treatment for humans exposed to high doses of radiation. PMID:25423021

  14. Effect of gamma radiation on the growth, survival, hematology and histological parameters of rainbow trout (Oncorhynchus mykiss) larvae.

    PubMed

    Oujifard, Amin; Amiri, Roghayeh; Shahhosseini, Gholamreza; Davoodi, Reza; Moghaddam, Jamshid Amiri

    2015-08-01

    Effects of low (1, 2.5 and 5Gy) and high doses (10, 20 and 40Gy) of gamma radiation were examined on the growth, survival, blood parameters and morphological changes of the intestines of rainbow trout (Oncorhynchus mykiss) larvae (103±20mg) after 12 weeks of exposure. Negative effects of gamma radiation on growth and survival were observed as radiation level and time increased. Changes were well documented at 10 and 20Gy. All the fish were dead at the dose of 40Gy. In all the treatments, levels of red blood cells (RBC), hematocrit (HCT) and hemoglobin (HB) were significantly (P<0.05) declined as the irradiation levels increased, whereas the amount of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) did not change. No significant differences (P>0.05) were found in the levels of white blood cells (WBC), lymphocytes and monocytes. Destruction of the intestinal epithelium cells was indicated as the irradiation levels increased to 1Gy and above. The highest levels of growth, survival, specific growth rate (SGR), condition factor (CF) and protein efficiency rate (PER) were obtained in the control treatment. The results showed that gamma rays can be a potential means for damaging rainbow trout cells. PMID:26141584

  15. Low Doses of Gamma-Irradiation Induce an Early Bystander Effect in Zebrafish Cells Which Is Sufficient to Radioprotect Cells

    PubMed Central

    Pereira, Sandrine; Malard, Véronique; Ravanat, Jean-Luc; Davin, Anne-Hélène; Armengaud, Jean; Foray, Nicolas; Adam-Guillermin, Christelle

    2014-01-01

    The term “bystander effect” is used to describe an effect in which cells that have not been exposed to radiation are affected by irradiated cells though various intracellular signaling mechanisms. In this study we analyzed the kinetics and mechanisms of bystander effect and radioadaptation in embryonic zebrafish cells (ZF4) exposed to chronic low dose of gamma rays. ZF4 cells were irradiated for 4 hours with total doses of gamma irradiation ranging from 0.01–0.1 Gy. In two experimental conditions, the transfer of irradiated cells or culture medium from irradiated cells results in the occurrence of DNA double strand breaks in non-irradiated cells (assessed by the number of ?-H2AX foci) that are repaired at 24 hours post-irradiation whatever the dose. At low total irradiation doses the bystander effect observed does not affect DNA repair mechanisms in targeted and bystander cells. An increase in global methylation of ZF4 cells was observed in irradiated cells and bystander cells compared to control cells. We observed that pre-irradiated cells which are then irradiated for a second time with the same doses contained significantly less ?-H2AX foci than in 24 h gamma-irradiated control cells. We also showed that bystander cells that have been in contact with the pre-irradiated cells and then irradiated alone present less ?-H2AX foci compared to the control cells. This radioadaptation effect is significantly more pronounced at the highest doses. To determine the factors involved in the early events of the bystander effect, we performed an extensive comparative proteomic study of the ZF4 secretomes upon irradiation. In the experimental conditions assayed here, we showed that the early events of bystander effect are probably not due to the secretion of specific proteins neither the oxidation of these secreted proteins. These results suggest that early bystander effect may be due probably to a combination of multiple factors. PMID:24667817

  16. Low doses of gamma-irradiation induce an early bystander effect in zebrafish cells which is sufficient to radioprotect cells.

    PubMed

    Pereira, Sandrine; Malard, Véronique; Ravanat, Jean-Luc; Davin, Anne-Hélène; Armengaud, Jean; Foray, Nicolas; Adam-Guillermin, Christelle

    2014-01-01

    The term "bystander effect" is used to describe an effect in which cells that have not been exposed to radiation are affected by irradiated cells though various intracellular signaling mechanisms. In this study we analyzed the kinetics and mechanisms of bystander effect and radioadaptation in embryonic zebrafish cells (ZF4) exposed to chronic low dose of gamma rays. ZF4 cells were irradiated for 4 hours with total doses of gamma irradiation ranging from 0.01-0.1 Gy. In two experimental conditions, the transfer of irradiated cells or culture medium from irradiated cells results in the occurrence of DNA double strand breaks in non-irradiated cells (assessed by the number of ?-H2AX foci) that are repaired at 24 hours post-irradiation whatever the dose. At low total irradiation doses the bystander effect observed does not affect DNA repair mechanisms in targeted and bystander cells. An increase in global methylation of ZF4 cells was observed in irradiated cells and bystander cells compared to control cells. We observed that pre-irradiated cells which are then irradiated for a second time with the same doses contained significantly less ?-H2AX foci than in 24 h gamma-irradiated control cells. We also showed that bystander cells that have been in contact with the pre-irradiated cells and then irradiated alone present less ?-H2AX foci compared to the control cells. This radioadaptation effect is significantly more pronounced at the highest doses. To determine the factors involved in the early events of the bystander effect, we performed an extensive comparative proteomic study of the ZF4 secretomes upon irradiation. In the experimental conditions assayed here, we showed that the early events of bystander effect are probably not due to the secretion of specific proteins neither the oxidation of these secreted proteins. These results suggest that early bystander effect may be due probably to a combination of multiple factors. PMID:24667817

  17. 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.

  18. Sensitometry of the response of a new radiochromic film dosimeter to gamma radiation and electron beams

    Microsoft Academic Search

    W. L. McLaughlin; Chen Yun-Dong; C. G. Soares; A. Miller; G. van Dyk; D. F. Lewis

    1991-01-01

    A new radiation-sensitive imaging material, called GafChromic™ Dosimetry Media, offers advances in high-dose radiation dosimetry and high-resolution radiography for gamma radiation and electrons. The potential uses in radiation processing, radiation sterilization of medical devices, population control of insects by irradiation, food irradiation, blood irradiation for organ-transplant immuno-suppression, clinical radiography, and industrial radiography have led to the present sensitometric study over

  19. MEASUREMENT OF THE HIGH GAMMA RADIATION DOSE USING THE MEMS BASED DOSIMETER AND RADIOLISYS EFFECT

    E-print Network

    Boyer, Edmond

    of high and very high doses of ionizing radiation is crucial for the monitoring of the existing Nuclear transducers, humidity sensors and , of course, radiation detectors and dosimeters. On the other hand, we-CEN in Belgium. Figure 1: Gamma radiation dose inside the vessel of the research nuclear reactor in Belgium

  20. Effect of gamma-radiation on cation transport across an artificial membrane

    Microsoft Academic Search

    V. Vijayavergiya; A. Mookerjee

    1989-01-01

    The effect of gamma radiation on cation transport across an artificial membrane has been measured. The membrane of 18C6 or phen in CHCl3 has been gammairradiated, and the radiation effect studied in terms of cation selectivity. The magnitude of transportation is increased under ionizing radiation specificity is changed from potassium to cesium and strontium to barium.

  1. Gamma Ray Telescope Senses High-Energy Radiation

    NSDL National Science Digital Library

    WNET

    2011-11-02

    This video from NASA describes the GLAST satellite, which is equipped with a gamma-ray telescope, and shares some background about the kinds of extreme universal phenomena indicated by the presence of gamma rays.

  2. Evidence for a Solar Influence on Gamma Radiation from Radon

    NASA Astrophysics Data System (ADS)

    Sturrock, P. A.; Steinitz, G.; Fischbach, E.; Javorsek, D.; Jenkins, J.

    2012-12-01

    We have analyzed 29,000 measurements of gamma radiation associated with the decay of radon confined to an airtight vessel at the Geological Survey of Israel (GSI) Laboratory in Jerusalem between January 28 2007 and May 10 2010. These measurements exhibit strong variations in time of year and time of day, which may be due in part to environmental influences. However, time-series analysis reveals a number of strong periodicities, including two at approximately 11.2 year-1 and 12.5 year-1. We consider it significant that these same oscillations have previously been detected in nuclear-decay data acquired at the Brookhaven National Laboratory and at the Physiklisch-Technische Bundesanstalt. We have suggested that these oscillations are due to some form of solar radiation (possibly neutrinos) that has its origin in the deep solar interior. A curious property of the GSI data is that the annual oscillation is much stronger in daytime data than in nighttime data, but the opposite is true for all other oscillations. Time-frequency analysis also yields quite different results from daytime and nighttime data. These procedures have also been applied to data collected from subsurface geological sites in Israel, Tenerife, and Italy, which have a variety of geological and geophysical scenarios, different elevations, and depths below the surface ranging from several meters to 1000 meters. In view of these results, and in view of the fact that there is at present no clear understanding of the behavior of radon in its natural environment, there would appear to be a need for multi-disciplinary research. Investigations that clarify the nature and mechanisms of solar influences may help clarify the nature and mechanisms of geological influences.

  3. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    The handbook discusses the history of GaAs solar cell development, presents equations useful for working with GaAs solar cells, describes commonly used instrumentation techniques for assessing radiation effects in solar cells and fundamental processes occurring in solar cells exposed to ionizing radiation, and explains why radiation decreases the electrical performance of solar cells. Three basic elements required to perform solar array degradation calculations: degradation data for GaAs solar cells after irradiation with 1 MeV electrons at normal incidence; relative damage coefficients for omnidirectional electron and proton exposure; and the definition of the space radiation environment for the orbit of interest, are developed and used to perform a solar array degradation calculation.

  4. Natural gamma-radiation in the Aeolian volcanic arc.

    PubMed

    Chiozzi, P; Pasquale, V; Verdoya, M; Minato, S

    2001-11-01

    Pulse-height distributions of gamma-rays, obtained with a field NaI(Tl) scintillation spectrometer in numerous sites of the Lipari and Vulcano islands (Aeolian volcanic arc, Italy), were measured to determine the U, Th and K concentrations of the bedrock and the relative values of the air absorbed dose rate. U is spatially related to both Th and K and the Th/U ratio is on average 3.1-3.5. The magmatic evolution is reflected by the concentration of the three radioelements, as they are more abundant within the more felsic units of the volcanic series. The higher values of U (15.7-20.0 ppm) coincide with higher Th (48.3-65.9 ppm) and K (4.9-6.1%) concentrations associated with rhyolitic rocks of the third cycle (< 50 ky). The air absorbed dose rate varies from 20 to 470 nGy h(-1). The highest values (> 350 nGy h(-1)) are observed on outcrops of rhyolitic obsidian lava flows. The cosmic-ray contribution is also evaluated to estimate the total background radiation dose rate. PMID:11573810

  5. APPLICATION OF JITTER RADIATION: GAMMA-RAY BURST PROMPT POLARIZATION

    SciTech Connect

    Mao, Jirong [Astrophysical Big Bang Lab, RIKEN, Saitama 351-0198 (Japan); Wang, Jiancheng, E-mail: jirong.mao@riken.jp [Yunnan Observatory, Chinese Academy of Sciences, 650011 Kunming, Yunnan Province (China)

    2013-10-10

    A high degree of polarization of gamma-ray burst (GRB) prompt emission has been confirmed in recent years. In this paper, we apply jitter radiation to study the polarization feature of GRB prompt emission. In our framework, relativistic electrons are accelerated by turbulent acceleration. Random and small-scale magnetic fields are generated by turbulence. We further determine that the polarization property of GRB prompt emission is governed by the configuration of the random and small-scale magnetic fields. A two-dimensional compressed slab, which contains a stochastic magnetic field, is applied in our model. If the jitter condition is satisfied, the electron deflection angle in the magnetic field is very small and the electron trajectory can be treated as a straight line. A high degree of polarization can be achieved when the angle between the line of sight and the slab plane is small. Moreover, micro-emitters with mini-jet structures are considered to be within a bulk GRB jet. The jet 'off-axis' effect is intensely sensitive to the observed polarization degree. We discuss the depolarization effect on GRB prompt emission and afterglow. We also speculate that the rapid variability of GRB prompt polarization may be correlated with the stochastic variability of the turbulent dynamo or the magnetic reconnection of plasmas.

  6. Gamma radiation effect on gas production in anion exchange resins

    NASA Astrophysics Data System (ADS)

    Traboulsi, A.; Labed, V.; Dauvois, V.; Dupuy, N.; Rebufa, C.

    2013-10-01

    Radiation-induced decomposition of Amberlite IRA400 anion exchange resin in hydroxide form by gamma radiolysis has been studied at various doses in different atmospheres (anaerobic, anaerobic with liquid water, and aerobic). The effect of these parameters on the degradation of ion exchange resins is rarely investigated in the literature. We focused on the radiolysis gases produced by resin degradation. When the resin was irradiated under anaerobic conditions with liquid water, the liquid phase over the resin was also analyzed to identify any possible water-soluble products released by degradation of the resin. The main products released are trimethylamine (TMA), molecular hydrogen (H2g) and carbon dioxide (CO2g). TMA and H2g are produced in all the irradiation atmospheres. However, TMA was in gaseous form under anaerobic and aerobic conditions and in aqueous form in presence of liquid water. In the latter conditions, TMAaq was associated with aqueous dimethylamine (DMAaq), monomethylamine (MMAaq) and ammonia (NH). CO2g is formed in the presence of oxygen due to oxidation of organic compounds present in the system, in particular the degradation products such as TMAg.

  7. Radiation-induced inhibition of thymidine incorporation in vivo as a measure of the initial slope and RBEn/. gamma

    SciTech Connect

    Dubravsky, N.B.; Maor, M.H.; Withers, H.R.

    1985-08-01

    Radiation damage can be measured by decreased incorporation of 3H-TdR. The early effect of total body irradiation of mice, with doses up to 300-400 rad, of gamma rays or neutrons, on thymidine-3H incorporation into the DNA of murine proliferating normal and tumor cells are described. Total body irradiation with single doses up to 300 rad resulted in a steep dose-dependent depression of 3H-TdR incorporation into the DNA of the jejunal crypt, testis, spleen, fibrosarcoma (FSa), and FSa metastasis cells. The dose required to depress 3H-TdR incorporation values to 37% of control level (D37/thymidine) after ..gamma..-irradiation was calculated to be 405, 443, 72, 303, and 531 rad, for jejunal crypt, testis, spleen, FSa metastasis, and FSa tumor cells, respectively. The depression progressed during the first 3 hours after irradiation. After neutron irradiation, the D37/thymidine was calculated to be 81, 140, 35, and 155 rad for jejunal crypt, testis, spleen, and FSa metastasis cells, respectively. The RBEn/..gamma.. derived from these results were 5.00, 3.16, 2.06, and 1.95 for jejunal crypt, testis, spleen, and FSa metastasis cells, respectively. These findings show that cell survival after small doses of irradiation correlate with the effect of irradiation on the actively proliferating cells at the time of irradiation.

  8. Development of an alpha/beta/gamma detector for radiation monitoring

    SciTech Connect

    Yamamoto, Seiichi [Kobe City College of Technology, 8-3, Gakuen-Higashi-machi, Nishi-ku, Kobe, 651-2194 (Japan); Hatazawa, Jun [Osaka University of Graduate School of Medicine, 2-2, Yamadaoka, Suita-shi, Osaka, 565-0871 (Japan)

    2011-11-15

    For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd{sub 2}SiO{sub 5} (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

  9. Development of an alpha/beta/gamma detector for radiation monitoring.

    PubMed

    Yamamoto, Seiichi; Hatazawa, Jun

    2011-11-01

    For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd(2)SiO(5) (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required. PMID:22128972

  10. Some neutron and gamma radiation characteristics of plutonium cermet fuel for isotopic power sources

    NASA Technical Reports Server (NTRS)

    Neff, R. A.; Anderson, M. E.; Campbell, A. R.; Haas, F. X.

    1972-01-01

    Gamma and neutron measurements on various types of plutonium sources are presented in order to show the effects of O-17, O-18 F-19, Pu-236, age of the fuel, and size of the source on the gamma and neutron spectra. Analysis of the radiation measurements shows that fluorine is the main contributor to the neutron yields from present plutonium-molybdenum cermet fuel, while both fluorine and Pu-236 daughters contribute significantly to the gamma ray intensities.

  11. Radiation damage in InP single crystals and solar cells

    Microsoft Academic Search

    Y. Yamaguchi; Chikao Uemura; Akio Yamamoto

    1984-01-01

    This paper shows that InP solar cell is more radiation resistant than Si and GaAs solar cells. Co-60 gamma-ray irradiation damage in InP solar cells was examined. Changes in minority carrier difffusion length and carrier concentration in irradiated InP single crystals were also investigated by electron beam induced current and capacitance-voltage methods for solar cells. A high carrier concentration p-InP

  12. Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

    DOEpatents

    Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

    2014-12-30

    A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

  13. Flash polymerization of silicone oils using gamma radiation for conserving waterlogged wood 

    E-print Network

    Gidden, Richmond Paul

    1996-01-01

    the SFD-I /SFD-5 mix. These bulked samples were exposed to gamma radiation emitted from a nuclear research reactor and received gamma doses ranging from 30 Gy to 228 Gy with dose rates ranging from 0.6 Gy/min to 5.1 Gy/min. Following irradiation, thin...

  14. Branching fractions and CP-violating asymmetries in radiative B decays to eta K gamma

    E-print Network

    Zhao, M.

    We present measurements of the CP-violation parameters S and C for the radiative decay B0-->etaKS0gamma; for B-->etaKgamma we also measure the branching fractions and for B+-->etaK+gamma the time-integrated charge asymmetry ...

  15. Gamma-delta T-cell lymphomas

    Microsoft Academic Search

    Emilio Iannitto; Ada Maria Florena; Carlo Ennio Pucillo; Pier Paolo Piccaluga; Vito Franco; Stefano Aldo Pileri; Claudio Tripodo

    2009-01-01

    Peripheral T-cell lymphomas (TCLs) are uncommon neoplasms, accounting for about 12% of all lymphoid tumors worldwide. TCLs in which ?? T-cell receptors are expressed (?? TCLs) are extremely aggressive and rare (<1% of lymphoid neoplasms). ?? TCLs originate from ?? T cells, a small subset of peripheral T cells with direct antigen recognition capability acting at the interface between innate

  16. Gamma Radiation Sensing Using ZnO and SnO2 Thick Film Interdigitated Capacitors

    Microsoft Academic Search

    K. Arshak; O. Korostynska; E. Jafer; A. Arshak; D. Morris; E. Gill

    2006-01-01

    A novel cost-effective real-time gamma radiation monitoring system based on metal oxide thick films was designed and tested. The changes in capacitances of ZnO and SnO2 thick film capacitors with interdigitated electrodes were monitored in real time under the influence of gamma radiation using miniaturized, low power, bi-directional wireless communication system. The capacitive interface circuitry was based on a Delta-sigma

  17. Airborne time-series measurement of soil moisture using terrestrial gamma radiation

    NASA Technical Reports Server (NTRS)

    Carroll, Thomas R.; Lipinski, Daniel M.; Peck, Eugene L.

    1988-01-01

    Terrestrial gamma radiation data and independent ground-based core soil moisture data are analyzed. They reveal the possibility of using natural terrestrial gamma radiation collected from a low-flying aircraft to make reliable real-time soil moisture measurements for the upper 20 cm of soil. The airborne data were compared to the crude ground-based soil moisture data set collected at the core sites.

  18. Accumulation of Mn(II) in Deinococcus radiodurans Facilitates GammaRadiation Resistance

    Microsoft Academic Search

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

    2004-01-01

    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

  19. Nonthermal Radiation of Cosmological Gamma-Ray Bursters

    NASA Astrophysics Data System (ADS)

    Smolsky, M. V.; Usov, V. V.

    2000-03-01

    We use 1.5 dimensional particle-in-cell plasma simulations to study the interaction of a relativistic, strongly magnetized wind with an ambient medium. Such an interaction is a plausible mechanism that leads to generation of cosmological ?-ray bursts. We confirm the idea of Mészáros & Rees that an essential part (about 20%) of the energy that is lost by the wind in the process of its deceleration may be transferred to high-energy electrons and then to high-frequency (X-ray and ?-ray) emission. We show that in the wind frame the spectrum of electrons that are accelerated at the wind front and move ahead of the front is nearly a two-dimensional relativistic Maxwellian with a relativistic temperature T=mec2?T/k~=6x109?T K, where ?T is equal to 200?0, with the accuracy of ~20%, and ?0 is the Lorentz factor of the wind, ?0>~102 for winds outflowing from cosmological ?-ray bursters. Our simulations point to an existence of a high-energy tail of accelerated electrons with a Lorentz factor of more than ~700?0. Large-amplitude electromagnetic waves are generated by the oscillating currents at the wind front. The mean field of these waves ahead of the wind front is an order of magnitude less than the magnetic field of the wind. High-energy electrons that are accelerated at the wind front and injected into the region ahead of the front generate synchro-Compton radiation in the fields of large-amplitude electromagnetic waves. This radiation closely resembles synchrotron radiation and can reproduce the nonthermal radiation of ?-ray bursts observed in the Ginga and BATSE ranges (from a few keV to a few MeV). Synchrotron photons that are generated in the vicinity of the wind front may be responsible for the radiation of ?-ray bursts in the EGRET energy range above a few ten MeV. The spectrum of ?-ray bursts in high-energy ?-rays may extend, in principle, up to the maximum energy of the accelerated electrons, which is about 1013(?0/102)2 eV in the frame of the ?-ray burster.

  20. The mechanical creep compliance of tissue cells is gamma distributed

    E-print Network

    John M. Maloney; Krystyn J. Van Vliet

    2011-07-13

    Investigations of natural variation among cells within a population are essential for understanding the stochastic nature of tissue cell deformation under applied load. In the existing literature, the population variation of single-cell creep compliance has so far been modeled universally by using a log-normal distribution. Here we use optical stretching, a non-contact and relatively high-throughput technique for probing cell mechanics, to accumulate a sufficient data set that demonstrates robustly that cell compliance varies according to the similar but distinct gamma distribution. Additionally, we re-examine existing simulations that were originally proposed to justify a log-normal fit, and show that in fact these simulation data also correspond to the gamma distribution. Finally, we propose a general stochastic differential equation that analytically predicts a gamma distribution of creep compliance during cell stretching, as well as the Gaussian distribution of cell recovery that we observe experimentally upon removal of applied load. The population variation is well characterized by just a single parameter in each of the creep and recovery regimes. We expect our correction of a phenomenological distribution fit, enabled by an expansive data set for mesenchymal stem cells, to enable the development of more accurate constitutive laws to describe cytoskeletal deformation. These findings thus serve to replace an empirical distribution with a better-fitting model that rests on a more solid experimental and theoretical foundation, and also provides a basis to predict and understand the stochastic nature of the mechanical response of individual cells within populations.

  1. The gamma ray content of ultrahigh energy cosmic radiation

    SciTech Connect

    Kolodziejczak, J.J.

    1990-01-01

    Data from the Utah-Michigan (UM) extensive air shower (EAS) array at Dugway, Utah are examined for evidence of a gamma ray component in the UHE cosmic rays. The UM array consist of a 3 {times} 10{sup 4} sq m surface array with 40 sq m of charged particle detectors, and a 1200 sq m buried array for detecting muons. Data from the large muon array are used to search for a gamma ray signature, since gamma rays are expected to produce far fewer muons in EAS than hadronic cosmic ray primaries. When no evidence for gamma rays is found, limits are set based on expected gamma ray behavior. For a photon energy threshold of 200 TeV, results include: a limit on the omnidirectional gamma ray fraction of cosmic rays at 0.2 pct; a limit on the galactic gamma ray fraction of cosmic rays at 7 {times} 10{sup {minus}5}; no strong evidence for enduring gamma ray point sources at fluxes approx. = 4 {times} 10{sup {minus}14}/sq cm/s; and no strong evidence for bursts on a one day time scale at a flux sensitivity {approx} 2 {times} 10{sup {minus}12}/sq cm/s. These limits and measurements are based on muon poor data. While no strong signal of UHE gamma rays is found, future application to the large Chicago Air Shower Array-Michigan Array (CASA-MIA) is possible.

  2. Protection of cellular DNA from gamma-radiation-induced damages and enhancement in DNA repair by troxerutin.

    PubMed

    Maurya, Dharmendra Kumar; Balakrishnan, Sreedevi; Salvi, Veena Prakash; Nair, Cherupally Krishnan Krishnan

    2005-12-01

    The effect of troxerutin on gamma-radiation-induced DNA strand breaks in different tissues of mice in vivo and formations of the micronuclei were studied in human peripheral blood lymphocytes ex vivo and mice blood reticulocytes in vivo. Treatments with 1 mM troxerutin significantly inhibited the micronuclei induction in the human lymphocytes. Troxerutin protected the human peripheral blood leucocytes from radiation-induced DNA strand breaks in a concentration dependent manner under ex vivo condition of irradiation (2 Gy). Intraperitoneal administration of troxerutin (175 mg/kg body weight) to mice before and after whole body radiation exposure inhibited micronuclei formation in blood reticulocytes significantly. The administration of different doses (75, 125 and 175 mg/kg body weight) of troxerutin 1 h prior to 4 Gy gamma-radiation exposure showed dose-dependent decrease in the yield of DNA strand breaks in murine blood leucocytes and bone marrow cells. The dose-dependent protection was more pronounced in bone marrow cells than in blood leucocytes. Administration of 175 mg/kg body weight of the drug (i.p.) 1 h prior or immediately after whole body irradiation of mice showed that the decrease in strand breaks depended on the post-irradiation interval at which the analysis was done. The observed time-dependent decrease in the DNA strand breaks could be attributed to enhanced DNA repair in troxerutin administered animals. Thus in addition to anti-erythrocytic, anti-thrombic, fibrinolytic and oedema-protective rheological activity, troxerutin offers protection against gamma-radiation-induced micronuclei formation and DNA strand breaks and enhances repair of radiation-induced DNA strand breaks. PMID:16311905

  3. Study of a number of biochemical indices of the blood and tissue of dogs after prolonged gamma-radiation

    NASA Technical Reports Server (NTRS)

    Alers, I.; Alersova, E.; Praslichka, T.; Mishurova, E.; Sedlakova, A.; Malatova, Z.; Akhunov, A. A.; Markelov, B. A.

    1974-01-01

    The glucose content in blood and the lipid content in serum and tissues of dogs exposed to chronic radiation for 3 and 5 years were studied. In tissues of these animals, the concentration of soluble DNA and DNA contained in DNP was studied in the spleen, lymph node (deep cervical node) and bone marrow of thigh bones. Results indicate that chronic gamma irradiation significantly changes concentrations of glucose in the blood, and that of several lipids in serum and tissues. A reduction in the concentration of DNP in tested organs reflects changes in the relative number of cells with various nuclear cytoplasmic ratios; most pronounced changes in biochemical indices occur in dogs exposed to chronic gamma radiation in doses of 125 rad per year.

  4. Phosphoinositide 3-kinase gamma participates in T cell receptor-induced T cell activation.

    PubMed

    Alcázar, Isabela; Marqués, Miriam; Kumar, Amit; Hirsch, Emilio; Wymann, Matthias; Carrera, Ana C; Barber, Domingo F

    2007-11-26

    Class I phosphoinositide 3-kinases (PI3Ks) constitute a family of enzymes that generates 3-phosphorylated polyphosphoinositides at the cell membrane after stimulation of protein tyrosine (Tyr) kinase-associated receptors or G protein-coupled receptors (GPCRs). The class I PI3Ks are divided into two types: class I(A) p85/p110 heterodimers, which are activated by Tyr kinases, and the class I(B) p110gamma isoform, which is activated by GPCR. Although the T cell receptor (TCR) is a protein Tyr kinase-associated receptor, p110gamma deletion affects TCR-induced T cell stimulation. We examined whether the TCR activates p110gamma, as well as the consequences of interfering with p110gamma expression or function for T cell activation. We found that after TCR ligation, p110gamma interacts with G alpha(q/11), lymphocyte-specific Tyr kinase, and zeta-associated protein. TCR stimulation activates p110gamma, which affects 3-phosphorylated polyphosphoinositide levels at the immunological synapse. We show that TCR-stimulated p110gamma controls RAS-related C3 botulinum substrate 1 activity, F-actin polarization, and the interaction between T cells and antigen-presenting cells, illustrating a crucial role for p110gamma in TCR-induced T cell activation. PMID:17998387

  5. Protection effects of condensed bromoacenaphthylene on radiation deterioration of ethylene-propylene-diene rubber. [Gamma radiation

    SciTech Connect

    Morita, Y.; Hagiwara, M.; Kasai, N.

    1982-09-01

    As a continuation of a series of the studies on the flame and ..gamma..-radiation resistant modification of ethylene-propylene-diene rubber (EPDM), condensed bromoacenaphthylene (con-BACN) as a newly developed flame retardant was synthesized and its effects on the radiation resistance of EPDM were investigated. The radiation resistance evaluated by measuring tensile properties of irradiated sheets of 2 mm thick was found improved greatly by adding con-BACN together with ordinary rubber ingredients but decreased by decabromodiphenylether (DBDPE) that has bromins in aromatic rings as con-BACN. When EPDM sheets of 1 mm thick were irradiated in oxygen at a dose rate of 1 X 10/sup 5/ rad/h, the weight swelling ratio increased with increasing dose, indicating that oxidative main chain scission is predominant under the irradiation conditions. On the other hand, crosslinking was shown to be predominant in nitrogen. From the results of the swelling experiments with different additives, it was concluded that DBDPE accelerates both the main chain scission in oxygen and the crosslinking in nitrogen. In contrast to this, con-BACN reduced the chain scission in oxygen. This observation was accounted by the assumption that the influence of the oxidative chain scission is partly compensated by the concurrent crosslinking which takes place through additions of con-BACN to substrate polymers even in the presence of oxygen.

  6. The myth of cell phone radiation

    E-print Network

    Vasant Natarajan

    2013-11-04

    We discuss the purported link between cell-phone radiation and cancer. We show that it is inconsistent with the photoelectric effect, and that epidemiological studies of any link have no scientific basis.

  7. Nature of gamma rays background radiation in new and old buildings of Qatar University

    SciTech Connect

    Al-Houty, L.; Abou-Leila, H.; El-Kameesy, S. (Qatar Univ., Doha (Qatar))

    1987-01-01

    Measurements and analysis of gamma-background radiation spectrum in four different places of Qatar University campus were performed at the energy range 10 keV-3 MeV using hyper pure Ge-detector. The dependence of the detector absolute photopeak efficiency on gamma-ray energies was determined and correction of the data for that was also done. The absorbed dose for each gamma line was calculated and an estimation of the total absorbed dose for the detected gamma lines in the four different places was obtained. Comparison with other results was also performed.

  8. Simulation of the gamma radiation field in lumpy environments

    Microsoft Academic Search

    B. J. Brennan; H. P. Schwarcz; W. J. Rink

    1997-01-01

    Many of the environments used for ESR and luminescence dating are inhomogeneous over the distances up to 0.3 m which contribute to gamma doses, and the consequent variability in gamma dose usually cannot be ascertained on a sample by sample basis. In this paper we examine the characteristics of such “lumpy” environments by simulation. Random environments were generated in which

  9. Effect of high doses of gamma radiation on the functional characteristics of amniotic membrane

    NASA Astrophysics Data System (ADS)

    Singh, Rita; Purohit, Sumita; Chacharkar, M. P.

    2007-06-01

    The effect of different doses of gamma radiation viz. 25, 36 and 50 kGy on the chemical and functional characteristics of the amniotic membrane was studied. The change in the chemical structure of amniotic membranes at high doses of gamma irradiation was evaluated by means of Infrared (IR) Spectroscopy. The degradation of amnion on irradiation with gamma rays could produce a relative variation in IR absorption troughs. This kind of variation was absent in the samples irradiated to doses of 25, 36 and 50 kGy indicating no qualitative change in the material property of amnion. No significant differences in the water absorption capacity and water vapour transmission rate of amniotic membranes irradiated to different doses were observed. Impermeability of the amniotic membranes to different microorganisms was also not affected at high doses of gamma radiation. Gamma irradiation at doses of 25-50 kGy did not evoke undesirable changes in the functional properties of the amniotic membrane.

  10. RADIATIVE PROCESSES (TAU ---> MU GAMMA, MU ---> E GAMMA AND MUON G-2) AS PROBES OF ESSM / SO(10)

    SciTech Connect

    Pati, Jogesh C

    2002-08-08

    The Extended Supersymmetric Standard Model (ESSM), motivated on several grounds, introduces two vectorlike families (16 + 16) of SO(10) with masses of order one TeV. It is noted that the successful predictions of prior work on fermion masses and mixings, based on MSSM embedded in SO(10), can be retained rather simply within the ESSM extension. These include an understanding of the smallness of V{sub cb} {approx} 0.04 and the largeness of {nu}{sub {mu}}-{nu}{sub {tau}} oscillation angle, sin{sup 2} 2{theta}{sub {nu}{sub {mu}}{nu}{sub {tau}}}{sup OSC} {approx} 1. We analyze the new contributions arising through the exchange of the vectorlike families of ESSM to radiative processes including {tau} {yields} {mu}{gamma}, {mu} {yields} e{gamma}, b {yields} s{gamma}, EDM of the muon and the muon (g-2). We show that ESSM makes significant contributions especially to the decays {tau} {yields} {mu}{gamma} and {mu} {yields} e{gamma} and simultaneously to muon (g-2). For a large and plausible range of relevant parameters, we obtain: a{sub {mu}}{sup ESSM} {approx} +(10-40) x 10{sup -10}, with a correlated prediction that {tau} {yields} {mu}{gamma} should be discovered with an improvement in its current limit by a factor of 3-20. The implications for {mu} {yields} e{gamma} are very similar. The muon EDM is within reach of the next generation experiments. Thus, ESSM with heavy leptons being lighter than about 700 GeV (say) can be probed effectively by radiative processes before a direct search for these vectorlike leptons and quarks is feasible at the LHC.

  11. Gamma radiation shielding and health physics characteristics of diaspore-flyash concretes.

    PubMed

    Singh, Kanwaldeep; Singh, Sukhpal; Singh, S P; Mudahar, Gurmel S; Dhaliwal, A S

    2015-06-01

    Different gamma radiation interaction parameters has been measured experimentally for the prepared diaspore-flyash concretes at 59.54, 662, 1173 and 1332?keV using narrow-beam transmission geometry and results are found to be in good agreement with theoretical values computed with a computer programme, WinXCom. The radiation exposure rate and absorbed dose rate for the gamma radiation with and without shielding of diaspore-flyash concretes have been determined using linear attenuation results. The results show that on average, there is reduction of 95%, 53% and 40% in dose rate for gamma sources (241)Am, (137)Cs and (60)Co, respectively with diaspore-flyash concretes as shielding material. Other health physics parameters namely equivalent dose, effective dose, gamma flux and energy fluence rate have also been determined. PMID:25946622

  12. Isodose mapping of terrestrial gamma radiation dose rate of Selangor state, Kuala Lumpur and Putrajaya, Malaysia.

    PubMed

    Sanusi, M S M; Ramli, A T; Gabdo, H T; Garba, N N; Heryanshah, A; Wagiran, H; Said, M N

    2014-09-01

    A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation. PMID:24787672

  13. Reliability studies on Si PIN photodiodes under Co-60 gamma radiation

    SciTech Connect

    Prabhakara Rao, Y. P. [Integrated Circuits Division, Bharat Electronics Limited, Bangalore, Karnataka-560013 (India) and Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore, Karnataka-570006 (India); Praveen, K. C.; Gnana Prakash, A. P. [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore, Karnataka-570006 (India); Rani, Y. Rejeena [Integrated Circuits Division, Bharat Electronics Limited, Bangalore, Karnataka-560013 (India)

    2013-02-05

    Silicon PIN photodiodes were fabricated with 250 nm SiO{sub 2} antireflective coating (ARC). The changes in the electrical characteristics, capacitance-voltage characteristics and spectral response after gamma irradiation are systematically studied to estimate the radiation tolerance up to 10 Mrad. The different characteristics studied in this investigation demonstrate that Si PIN photodiodes are suitable for high radiation environment.

  14. Dosimetric criteria of canine mortality following total-body nonuniform irradiation. [Gamma radiation, dogs

    Microsoft Academic Search

    V. L. Gozenbuk; I. B. Keirim-Markus

    1977-01-01

    Results of previous experiments involving nonuniform exposure of dogs to gamma radiation were used for analysis of dosimetric criteria. The equivalent dose characterizes the probability of survival after sustaining the bone marrow form of radiation lesion. In the equivalent dose formula, the function P(D) is hemopoietic activity as a function of dosage. With doses up to 1200 rad, involvement of

  15. Radiation-Induced Carcinogenesis: Mechanistically Based Differences between Gamma-Rays and Neutrons, and

    E-print Network

    Brenner, David Jonathan

    Radiation-Induced Carcinogenesis: Mechanistically Based Differences between Gamma-Rays and Neutrons effect). Densely ionizing radiation (e.g. neutrons) often produces downwardly curving dose responses exposed to high or low dose rates of c-rays and neutrons, either with or without pre

  16. Response of thyroid follicular cells to gamma irradiation compared to proton irradiation. I. Initial characterization of DNA damage, micronucleus formation, apoptosis, cell survival, and cell cycle phase redistribution

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Murray, D. K.; Bant, A. M.; Kazarians, G.; Moyers, M. F.; Nelson, G. A.; Tran, D. T.

    2001-01-01

    The RBE of protons has been assumed to be equivalent to that of photons. The objective of this study was to determine whether radiation-induced DNA and chromosome damage, apoptosis, cell killing and cell cycling in organized epithelial cells was influenced by radiation quality. Thyroid-stimulating hormone-dependent Fischer rat thyroid cells, established as follicles, were exposed to gamma rays or proton beams delivered acutely over a range of physical doses. Gamma-irradiated cells were able to repair DNA damage relatively rapidly so that by 1 h postirradiation they had approximately 20% fewer exposed 3' ends than their counterparts that had been irradiated with proton beams. The persistence of free ends of DNA in the samples irradiated with the proton beam implies that either more initial breaks or a quantitatively different type of damage had occurred. These results were further supported by an increased frequency of chromosomal damage as measured by the presence of micronuclei. Proton-beam irradiation induced micronuclei at a rate of 2.4% per gray, which at 12 Gy translated to 40% more micronuclei than in comparable gamma-irradiated cultures. The higher rate of micronucleus formation and the presence of larger micronuclei in proton-irradiated cells was further evidence that a qualitatively more severe class of damage had been induced than was induced by gamma rays. Differences in the type of damage produced were detected in the apoptosis assay, wherein a significant lag in the induction of apoptosis occurred after gamma irradiation that did not occur with protons. The more immediate expression of apoptotic cells in the cultures irradiated with the proton beam suggests that the damage inflicted was more severe. Alternatively, the cell cycle checkpoint mechanisms required for recovery from such damage might not have been invoked. Differences based on radiation quality were also evident in the alpha components of cell survival curves (0.05 Gy(-1) for gamma rays, 0.12 Gy(-1) for protons), which suggests that the higher level of survival of gamma-irradiated cells could be attributed to the persistence of nonlethally irradiated thyrocytes and/or the capacity to repair damage more effectively than cells exposed to equal physical doses of protons. The final assessment in this study was radiation-induced cell cycle phase redistribution. Gamma rays and protons produced a similar dose-dependent redistribution toward a predominantly G(2)-phase population. From our cumulative results, it seems likely that a majority of the proton-irradiated cells would not continue to divide. In conclusion, these findings suggest that there are quantitative and qualitative differences in the biological effects of proton beams and gamma rays. These differences could be due to structured energy deposition from the tracks of primary protons and the associated high-LET secondary particles produced in the targets. The results suggest that a simple dose-equivalent approach to dosimetry may be inadequate to compare the biological responses of cells to photons and protons.

  17. Terrestrial gamma radiation dose study to determine the baseline for environmental radiological health practices in Melaka state, Malaysia

    Microsoft Academic Search

    Ahmad Termizi Ramli; Sallehudin Sahrone; Husin Wagiran

    2005-01-01

    Environmental terrestrial gamma radiation dose rates were measured throughout Melaka, Malaysia, over a period of two years, with the objective of establishing baseline data on the background radiation level. Results obtained are shown in tabular, graphic and cartographic form. The values of terrestrial gamma radiation dose rate vary significantly over different soil types and for different underlying geological characteristics present

  18. Reflectivity of linear and nonlinear gamma radiated apodized chirped Bragg grating under ocean

    SciTech Connect

    Hamdalla, Taymour A. [Faculty of Science, Alexandria University, Alexandria (Egypt); Faculty of Science, Tabuk University, Tabuk (Saudi Arabia)

    2012-09-06

    In this paper, the effect Co{sup 60} gamma radiation is investigated on the effective refractive index of apodized chirped Bragg grating. Nine apodization profiles are considered. Comparison between the reflectivity of the gamma radiated and non radiated fiber Bragg grating has been carried out. The electric field of signals propagating through the apodized chirped fiber Bragg grating (ACFBG) is first calculated from which, new values for the refractive index are determined. The nonlinear effects appear on the ACFBG reflectivity. The effect of nonlinearity and undersea temperature and pressure on the grating is also studied.

  19. Interaction of deep impurities with radiation defects in n-Si at gamma-irradiation

    NASA Astrophysics Data System (ADS)

    Makhkamov, S.; Karimov, M.; Khakimov, Z. M.; Odilova, N. D.; Makhmudov, S. A.; Kurbanov, A. O.; Begmatov, K. A.

    2005-08-01

    This work presents the results of research on peculiarities of radiation defect formation in single crystal n-Si, doped by deep level impurities (Cu, Ni, Ir, Rh, Pt and Au), at irradiation by gamma-quanta of 60 Co. A property of gamma-irradiation to create only vacancies and self-interstitial atoms is used to understand the nature of deep levels with participation of these impurities and primary elemental radiation defects. The role of covalence radii and diffusion coefficients in efficiency of radiation defect formation is discussed.

  20. Simultaneous measurement of neutron and gamma-ray radiation levels from a TRIGA reactor core using silicon carbide semiconductor detectors

    Microsoft Academic Search

    A. R. Dulloo; F. H. Ruddy; J. G. Seidel; C. Davison; T. Flinchbaugh; T. Daubenspeck

    1998-01-01

    The ability of a SiC detector to measure neutron and gamma radiation levels in a TRIGA reactor's mixed neutron\\/gamma field was demonstrated. Linear responses to an epicadmium neutron fluence rate (up to 3×107 cm-2 s-1) and to a gamma dose rate (0.6-234 krad-Si h-1) were obtained with the detector. Axial profiles of the reactor core's neutron and gamma-ray radiation levels

  1. Up-regulation of Bcl-2 expression in cultured human lymphocytes after exposure to low doses of gamma radiation

    PubMed Central

    Azimian, Hosein; Bahreyni-Toossi, Mohammad Taghi; Rezaei, Abdul Rahim; Rafatpanah, Houshang; Hamzehloei, Tayebeh; Fardid, Reza

    2015-01-01

    Lymphocytes have demonstrated complex molecular responses to induced stress by ionizing radiation. Many of these reactions are mediated through modifications in gene expressions, including the genes involved in apoptosis. The primary aim of this study was to assess the effects of low doses of ionizing radiation on the apoptotic genes, expression levels. The secondary goal was to estimate the time-effect on the modified gene expression caused by low doses of ionizing radiation. Mononuclear cells in culture were exposed to various dose values ranged from 20 to 100 mGy by gamma rays from a Cobalt-60 source. Samples were taken for gene expression analysis at hours 4, 24, 48, 72, and 168 following to exposure. Expression level of two apoptotic genes; BAX (pro-apoptotic) and Bcl-2 (anti-apoptotic) were examined by relative quantitative real-time polymerase chain reaction (PCR), at different time intervals. Radio-sensitivity of peripheral blood mononucleated cells (PBMCs) was measured by the Bcl-2/BAX ratio (as a predictive marker for radio-sensitivity). The non-parametric two independent samples Mann–Whitney U-test were performed to compare means of gene expression. The results of this study revealed that low doses of gamma radiation can induce early down-regulation of the BAX gene of freshly isolated human PBMCs; however, these changes were restored to near normal levels after 168 hours. In most cases, expression of the Bcl-2 anti-apoptotic gene was up-regulated. Four hours following to exposure to low doses of gamma radiation, apoptotic gene expression is modified, this is manifested as adaptive response. Modification of these gene expressions seems to be a principle pathway in the early radioresistance response. In our study, we found that these changes were temporary and faded completely within a week.

  2. Snowpack snow water equivalent measurement using the attenuation of cosmic gamma radiation

    SciTech Connect

    Osterhuber, R. [Univ. of California, Soda Springs, CA (United States). Central Sierra Snow Lab.; Fehrke, F. [California Dept. of Water Resources, Sacramento, CA (United States); Condreva, K. [Sandia National Labs., Livermore, CA (United States)

    1998-05-01

    Incoming, background cosmic radiation constantly fluxes through the earth`s atmosphere. The high energy gamma portion of this radiation penetrates many terrestrial objects, including the winter snowpack. The attenuation of this radiation is exponentially related to the mass of the medium through which it penetrates. For the past three winters, a device measuring cosmic gamma radiation--and its attenuation through snow--has been installed at the Central Sierra Snow Laboratory, near Donner Pass, California. This gamma sensor, measuring energy levels between 5 and 15 MeV, has proved to be an accurate, reliable, non-invasive, non-mechanical instrument with which to measure the total snow water equivalent of a snowpack. This paper analyzes three winters` worth of data and discusses the physics and practical application of the sensor for the collection of snow water equivalent data from a remote location.

  3. Formulation of a nasogastric liquid feed and shelf-life extension using gamma radiation.

    PubMed

    Hajare, Sachin N; Gautam, Satyendra; Nair, Anjali B; Sharma, Arun

    2014-08-01

    Nasogastric liquid feed formulation (NGLF) was developed for immunocompromised patients who are vulnerable targets of pathogenic assault. NGLF consisted of cereals, pulses, vegetables, and milk powder to provide balanced nutrients; however, the shelf life was only a few hours because this product was highly prone to microbial contamination and proliferation due to its high water content and rich nutrients. Postpreparation storage and distribution was very difficult, even at chilled temperatures. To overcome this problem, the NGLF was irradiated at various doses (2.5 to 10 kGy). Gamma irradiation at 10 kGy reduced the microbial load to nondetectable levels, and the product could be stored up to 1 month without any detectable increase in microbial load. The sensory evaluation did not indicate differences between the nonirradiated fresh, irradiated fresh, and stored samples. Nutritional quality in terms of total carbohydrates, dietary fiber, proteins, calories, vitamins A and C, and the micronutrients calcium, iron, and zinc was not affected by irradiation. NGLF also possessed antimutagenic potential against ethylmethanesulphonate-induced mutagenesis in Escherichia coli cells as evaluated by the rifampin resistance assay. This property of NGLF remained unchanged even after exposure to a 10-kGy dose of gamma radiation. Thus, irradiated NGLF seemed to be a safe and wholesome food for immunocompromised patients. PMID:25198591

  4. Multiple fractions of gamma rays induced resistance to cis-dichloro-diammineplatinum (II) and methotrexate in human HeLa cells

    SciTech Connect

    Osmak, M.; Perovic, S. (Ruder Boskovic Institute, Croatia (Yugoslavia))

    1989-06-01

    Previous irradiation could induce changes in the cell-sensitivity to additional cytotoxic agents. In this study we examined whether the sensitivity to additional cytotoxic agents was affected in cells irradiated with multiple fractions of gamma rays if these agents were given at the time when the lesions induced in DNA by radiation have already been repaired. Human cervix carcinoma HeLa cells were irradiated daily with 0.5 Gy of gamma rays five times a week for 6 weeks. When the fractionation regimen was completed, that is when the cells had accumulated the total dose of 15 Gy of gamma rays, the sensitivity of these cells to gamma rays, UV light, cis-dichlorodiammineplatinum (II) (cis-DDP), methotrexate (MTX), and hydroxyurea (HU) was examined and compared to control cells. Results revealed that preirradiated cells did not change sensitivity to gamma rays and UV light, but that they increased the resistance to cis-DDP, and MTX (especially for higher concentrations of MTX), and increased sensitivity to HU (for lower concentrations of HU). The increased resistance to cis-DDP was also measurable up to 30 days after the last dose of gamma rays. The results indicate that preirradiation of HeLa cells with multiple fractions of gamma rays could change their sensitivity to additional cytotoxic agents, and that this is a relatively long-lasting effect. Our results suggest that caution is needed in medical application of radiation combined with chemical treatment.

  5. Radiation chemistry of salt-mine brines and hydrates. [Gamma radiation

    SciTech Connect

    Jenks, G.H.; Walton, J.R.; Bronstein, H.R.; Baes, C.F. Jr.

    1981-07-01

    Certain aspects of the radiation chemistry of NaCl-saturated MgCl/sub 2/ solutions and MgCl/sub 2/ hydrates at temperatures in the range of 30 to 180/sup 0/C were investigated through experiments. A principal objective was to establish the values for the yields of H/sub 2/ (G(H/sub 2/)) and accompanying oxidants in the gamma-ray radiolysis of concentrated brines that might occur in waste repositories in salt. We concluded that G(H/sub 2/) from gamma-irradiated brine solution into a simultaneously irradiated, deaerated atmosphere above the solution is between 0.48 and 0.49 over most of the range 30 to 143/sup 0/C. The yield is probably somewhat lower at the lower end of this range, averaging 0.44 at 30 to 45/sup 0/C. Changes in the relative amounts of MgCl/sub 2/ and NaCl in the NaCl-saturated solutions have negligible effects on the yield. The yield of O/sub 2/ into the same atmosphere averages 0.13, independent of the temperature and brine composition, showing that only about 50% of the radiolytic oxidant that was formed along with the H/sub 2/ was present as O/sub 2/. We did not identify the species that compose the remainder of the oxidant. We concluded that the yield of H/sub 2/ from a gamma-irradiated brine solution into a simultaneously irradiated atmosphere containing 5 to 8% air in He may be greater than the yield in deaerated systems by amounts ranging from 0% for temperatures of 73 to 85/sup 0/C, to about 30 and 40% for temperatures in the ranges 100 to 143/sup 0/C and 30 to 45/sup 0/C, respectively. We did not establish the mechanism whereby the air affected the yields of H/sub 2/ and O/sub 2/. The values found in this work for G(H/sub 2/) in deaerated systems are in approximate agreement with the value of 0.44 for the gamma-irradiation yield of H/sub 2/ in pure H/sub 2/O at room temperature. They are also in agreement with the values predicted by extrapolation from the findings of previous researchers for the value for G(H/sub 2/) in 2 M NaCl solutions at room temperature.

  6. Interferon-gamma and TRAIL in human breast tumor cells.

    PubMed

    Ruiz de Almodóvar, Carmen; López-Rivas, Abelardo; Ruiz-Ruiz, Carmen

    2004-01-01

    Induction of apoptosis in tumor cells by death receptor activation is a novel therapeutic strategy. However, in systemic antitumor treatments, severe toxic effects have been observed with tumor necrosis factor-alpha (TNF-alpha) and CD95 ligand. TNF-alpha causes a lethal inflammatory response and CD95L produces lethal liver damage. Preclinical studies in mice and nonhuman primates showed no systemic cytotoxicity upon injection of recombinant TNF-related apoptosis-inducing ligand (TRAIL) at doses that effectively suppressed solid tumors such as colon and mammary carcinomas. Although unwanted effects of some TRAIL preparations have been reported in normal cells, these data suggest that TRAIL could be a suitable approach in cancer therapy. However, several mechanisms of resistance to TRAIL-mediated apoptosis have been described in tumor cells such as lack of TRAIL apoptotic receptors, enhanced expression of TRAIL-decoy receptors, and expression of apoptosis inhibitors. In combination regimes, interferon-gamma (IFN-gamma) could provide a promising antitumor therapeutic approach as it has been described to enhance cellular susceptibility to apoptosis in a variety of tumor cells. The mechanism by which IFN-gamma promotes cell death seems to be via the regulation of the expression of different proteins involved in apoptosis. Altogether, these data suggest a combination strategy to selectively kill tumor cells that need to be further explored. PMID:15110183

  7. Improved radiation hardness of silicon solar cells

    Microsoft Academic Search

    Hidetoshi Washio; Yoshifumi Tonomura; Minoru Kaneiwa; Tatsuo Saga; O. Anzawa; S. Matsuda

    2000-01-01

    SHARP and NASDA (National Space Development Agency of Japan) have been engaged in the development of silicon space solar cells since 1970s. We started the project to improve the radiation hardness of silicon solar cells in 1998. This project gave fruitful results in BJ (both-side junction) and AHES (advanced high efficiency silicon) structure. The design and manufacturing process for the

  8. Investigation of {gamma} radiation from {sup 178}Hf in the respective (n, n Prime {gamma}) reaction

    SciTech Connect

    Govor, L. I.; Demidov, A. M.; Kurkin, V. A., E-mail: kurkin@polyn.kiae.su; Mikhailov, I. V. [National Research Center Kurchatov Institute (Russian Federation)

    2012-12-15

    The spectra and angular distributions of gamma rays were measured in the reaction {sup 178}Hf(n, n Prime {gamma}) induced by a beam of fast reactor neutrons. Data onmultipole mixtures in gamma transitions and a lot of new information about gamma transitions of energy 1.5 to 3.0 MeV were obtained. A comparison of these results with information known from the respective (n, {gamma}) reaction made it possible to refine the schemes of deexcitation of {sup 178}Hf levels at energies above 1.5 MeV, to determine more precisely features of these levels, and to introduce new levels and rotation bands at excitation energies of about 2MeV.

  9. Clinical Applications of Gamma Delta T Cells with Multivalent Immunity

    PubMed Central

    Deniger, Drew C.; Moyes, Judy S.; Cooper, Laurence J. N.

    2014-01-01

    ?? T cells hold promise for adoptive immunotherapy because of their reactivity to bacteria, viruses, and tumors. However, these cells represent a small fraction (1–5%) of the peripheral T-cell pool and require activation and propagation to achieve clinical benefit. Aminobisphosphonates specifically expand the V?9V?2 subset of ?? T cells and have been used in clinical trials of cancer where objective responses were detected. The V?9V?2 T cell receptor (TCR) heterodimer binds multiple ligands and results in a multivalent attack by a monoclonal T cell population. Alternatively, populations of ?? T cells with oligoclonal or polyclonal TCR repertoire could be infused for broad-range specificity. However, this goal has been restricted by a lack of applicable expansion protocols for non-V?9V?2 cells. Recent advances using immobilized antigens, agonistic monoclonal antibodies (mAbs), tumor-derived artificial antigen presenting cells (aAPC), or combinations of activating mAbs and aAPC have been successful in expanding gamma delta T cells with oligoclonal or polyclonal TCR repertoires. Immobilized major histocompatibility complex Class-I chain-related A was a stimulus for ?? T cells expressing TCR?1 isotypes, and plate-bound activating antibodies have expanded V?1 and V?2 cells ex vivo. Clinically sufficient quantities of TCR?1, TCR?2, and TCR?1negTCR?2neg have been produced following co-culture on aAPC, and these subsets displayed differences in memory phenotype and reactivity to tumors in vitro and in vivo. Gamma delta T cells are also amenable to genetic modification as evidenced by introduction of ?? TCRs, chimeric antigen receptors, and drug-resistance genes. This represents a promising future for the clinical application of oligoclonal or polyclonal ?? T cells in autologous and allogeneic settings that builds on current trials testing the safety and efficacy of V?9V?2 T cells. PMID:25566249

  10. Breast cancer stem cells and radiation

    NASA Astrophysics Data System (ADS)

    Phillips, Tiffany Marie

    2007-12-01

    The present studies explore the response of breast cancer stem cells (BCSC's) to radiation and the implications for clinical cancer treatment. Current cancer therapy eliminates bulky tumor mass but may fail to eradicate a critical tumor initiating cell population termed "cancer stem cells". These cells are potentially responsible for tumor formation, metastasis, and recurrence. Recently cancer stem cells have been prospectively identified in various malignancies, including breast cancer. The breast cancer stem cell has been identified by the surface markers CD44+/CD24 -(low). In vitro mammosphere cultures allow for the enrichment of the cancer stem cell population and were utilized in order to study differential characteristics of BCSC's. Initial studies found that BCSC's display increased radiation resistance as compared to other non-stem tumor cells. This resistance was accompanied by decreased H2AX phosphorylation, decreased reactive oxygen species formation, and increased phosphorylation of the checkpoint protein Chk1. These studies suggest differential DNA damage and repair within the BCSC population. Studies then examined the consequences of fractionated radiation on the BCSC population and found a two-fold increase in BCSC's following 5 x 3Gy. This observation begins to tie cancer stem cell self-renewal to the clinical stem cell phenomenon of accelerated repopulation. Accelerated repopulation is observed when treatment gaps increase between sequential fractions of radiotherapy and may be due to cancer stem cell symmetric self-renewal. The balance between asymmetric and symmetric stem cell division is vital for proper maintenance; deregulation is likely linked to cancer initiation and progression. The developmental Notch-1 pathway was found to regulate BCSC division. Over-expressing the constitutively active Notch-1-ICD in MCF7 cells produced an increase in the BCSC population. Additionally, radiation was observed to increase the expression of the Notch-1 ligand, Jagged-1, and this was complemented by radiation induced Notch-1 activation. Studies also linked hypoxia and BCSC renewal through Epo signaling. Treatment with rhEpo induced an increase in BCSC's, which again was due to rhEpo induced Jagged-1 expression and subsequent Notch-1 activation. This thesis suggests that radiation and rhEpo induce Jagged-1 expression in non-stem cells, which then induce Notch-1 activation in adjacent stem cells, and results in symmetric cancer stem cell self-renewal.

  11. Inactivation of Bacillus Spores by Ultraviolet or Gamma Radiation

    Microsoft Academic Search

    Ernest R. Blatchley; Anne Meeusen; Arthur I. Aronson

    2005-01-01

    Bacillus anthracis spores represent an important bioterrorism agent that can be dispersed in air or water. Existing decontami- nation practices based on these spores have focused on chemical disinfectants; however, the basic characteristics of radiation-based disinfectants suggest potential advantages in their application for control of Bacillus spores. Experiments were conducted to examine the effectiveness of ultraviolet UV254 radiation and radiation

  12. PROTECTION OF SINGLE CELLS AND SMALL CELL GROUPS AGAINST RADIATION

    Microsoft Academic Search

    S. Bellack; A. T. Krebs

    1951-01-01

    The protective effects against radiation injury of a number of chemicals ; were investigated in ioion epidermis cells exposed to x radiation both before and ; after treatment. A protsctive effect was observed for cystained with cystine, ; urea, and NaCl solutions. (C.H.);

  13. Absorption of 10--200 Gev Gamma Rays by Radiation from BLR in Blazars

    E-print Network

    H. T. Liu; J. M. Bai

    2008-07-20

    In this paper, we study the photon-photon pair production optical depth for gamma-rays with energies from 10 to 200 GeV emitted by powerful blazars due to the diffuse radiation field of broad line region (BLR). There are four key parameters in the BLR model employed to determine the $\\gamma-\\gamma$ attenuation optical depth of these gamma-rays. They are the gamma-ray emitting radius $R_{\\gamma}$, the BLR luminosity $L_{\\rm{BLR}}$, the BLR half thickness $h$ and the ratio $\\tau_{\\rm{BLR}}/f_{\\rm{cov}}$ of the Thomson optical depth to the covering factor of BLR. For FSRQs, on average, it is impossible for gamma-rays with energies from 10 to 200 GeV to escape from the diffuse radiation field of the BLR. If $\\it GLAST$ could detect these gamma-rays for most of FSRQs, the gamma-ray emitting region is likely to be outside the cavity formed by the BLR. Otherwise, the emitting region is likely to be inside the BLR cavity. As examples, we estimate the photon-photon absorption optical depth of gamma-rays with energies from 10 to 200 GeV for two powerful blazars, HFSRQ PKS 0405$-$123 and FSRQ 3C 279. Comparing our results with $\\it GLAST$ observations in the future could test whether the model employed and the relevant assumptions in this paper are reliable and reasonable, and then limit constraints on the position of the gamma-ray emitting region relative to the BLR and the properties of the BLR.

  14. Unraveling low-level gamma radiation--responsive changes in expression of early and late genes in leaves of rice seedlings at Iitate Village, Fukushima.

    PubMed

    Hayashi, Gohei; Shibato, Junko; Imanaka, Tetsuji; Cho, Kyoungwon; Kubo, Akihiro; Kikuchi, Shoshi; Satoh, Kouji; Kimura, Shinzo; Ozawa, Shoji; Fukutani, Satoshi; Endo, Satoru; Ichikawa, Katsuki; Agrawal, Ganesh Kumar; Shioda, Seiji; Fukumoto, Manabu; Rakwal, Randeep

    2014-01-01

    In the summer of 2012, 1 year after the nuclear accident in March 2011 at the Fukushima Daiichi nuclear power plant, we examined the effects of gamma radiation on rice at a highly contaminated field of Iitate village in Fukushima, Japan. We investigated the morphological and molecular changes on healthy rice seedlings exposed to continuous low-dose gamma radiation up to 4 µSv h(-1), about 80 times higher than natural background level. After exposure to gamma rays, expression profiles of selected genes involved in DNA replication/repair, oxidative stress, photosynthesis, and defense/stress functions were examined by RT-PCR, which revealed their differential expression in leaves in a time-dependent manner over 3 days (6, 12, 24, 48, and 72 h). For example, OsPCNA mRNA rapidly increased at 6, 12, and 24 h, suggesting that rice cells responded to radiation stress by activating a gene involved in DNA repair mechanisms. At 72 h, genes related to the phenylpropanoid pathway (OsPAL2) and cell death (OsPR1oa) were strongly induced, indicating activation of defense/stress responses. We next profiled the transcriptome using a customized rice whole-genome 4×44K DNA microarray at early (6h) and late (72 h) time periods. Low-level gamma radiation differentially regulated rice leaf gene expression (induced 4481 and suppressed 3740 at 6 h and induced 2291 and suppressed 1474 genes at 72 h) by at least 2-fold. Using the highly upregulated and downregulated gene list, MapMan bioinformatics tool generated diagrams of early and late pathways operating in cells responding to gamma ray exposure. An inventory of a large number of gamma radiation-responsive genes provides new information on novel regulatory processes in rice. PMID:25124817

  15. Effect of dexamethasone on the cytotoxic and enzymatic response of cultured endothelial cells to radiation

    Microsoft Academic Search

    T. T. Lam; D. B. Rubin; E. A. Drab

    1985-01-01

    Experiments were conducted to determine (1) whether glucocorticoids directly protected endothelial cells (EC) from radiation and (2) if angiotensin converting enzyme (ACE) activity, known to be increased by glucocorticoid, played a role in the EC response to radiation. Confluent monolayers of EC cultured from bovine aorta EC were treated with dexamethasone (10⁻⁶ M); after irradiation (5.0 Gy, ⁶°Co ..gamma..) ACE

  16. Monoamine oxidase inhibitors l-deprenyl and clorgyline protect nonmalignant human cells from ionising radiation and chemotherapy toxicity

    Microsoft Academic Search

    C B Seymour; C Mothersill; R Mooney; M Moriarty; K F Tipton

    2003-01-01

    l-Deprenyl (R-(?)-deprenyl, selegiline) is an inhibitor of monoamine oxidase-B (MAO-B) that is known to protect nerve cells from a variety of chemical and physical insults. As apoptosis is a common mechanism of radiation-induced cell death, the effect of l-deprenyl on the survival of cultured cells and tissue explants was studied following exposure to gamma radiation. The results obtained were compared

  17. Extending the response of the sum coincidence spectrometer to multiple gamma radiation cascades 

    E-print Network

    Helton, Victor Dean

    1964-01-01

    for the degree of MASTER OF SCIENCE August, l964, Major Subject: Physics EXTENDING THE RESPONSE OF THE SUM COINCIDENCE SPECTROMETER TO MULTIPLE GAMMA RADIATION CASCADES A Thesis By VICTOR DEAN HELTON Approved as to style and content by: i / C airman... BIBLIOGRAPHY ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ o ~ 52 LIST OF FIGURES Figure Page 1. The Sum Coincidence Spectrometer . ~ ~ ~ ~ ~ ~ 11 2. The Three Gamma-Ray Cascade . . . . . . . . . 14 3 The Coincidence-Sum Spectrometer . . . . . . . 20 4, ~ 5...

  18. Amplification of Gamma Radiation from X-Ray Excited Nuclear States

    E-print Network

    Silviu Olariu

    1999-07-18

    In this paper we discuss the possibility of the excitation of nuclear electromagnetic transitions by the absorption of X-ray quanta produced in appropriate inner-shell atomic transitions, and the relevance of this process for the amplification of the gamma radiation from the excited nuclear states. It is concluded that the X-ray pumping technique might provide a useful approach for the development of a gamma ray laser.

  19. HEALTH HAZARDS FROM FISSION PRODUCTS AND FALLOUT. II. GAMMA RADIATION FROM NUCLEAR WEAPONS FALLOUT

    Microsoft Academic Search

    Bjornerstedt

    1960-01-01

    Methods of estimating the gamma radiation from fallout and fission ; products are discussed. (Gamma spectra and 0.1 Mev energy intervals for 101 ; fissions were calculated for the following times after fission: 1. 2. 5. and 10 ; hours; years. Fifty energy groups of width 1.300 to 1.399 Mev were used, ; covering the range 0.0 to 5.0 Mev.

  20. Gamma-Ray Induced Radiation Damage in Large Size LSO and LYSO Crystal Samples

    Microsoft Academic Search

    Jianming Chen; Rihua Mao; Liyuan Zhang; Ren-Yuan Zhu

    2007-01-01

    This paper presents a study of the gamma-ray induced radiation damage effect in large size (2.5 times 2.5 times 20 cm3) LSO and LYSO crystal samples. Optical and scintillation properties, including longitudinal transmittance and photo-luminescence spectra, light output and light response uniformity with PMT and APD readout, are measured before and after gamma-ray irradiations with an integrated dose up to

  1. A radiation transport model as a design tool for gamma densitometers

    Microsoft Academic Search

    E. Åbro; G. A. Johansen; H. Opedal

    1999-01-01

    A flexible EGS4 Monte Carlo model was developed to simulate radiation transport in low-energy gamma-ray densitometers which are used for void (gas) fraction measurements in gas\\/liquid pipe flows. The detector responses produced by the model with 241Am gamma-ray input proved to be accurate in benchmarking experiments using real data. The verification was performed with homogeneous mixed flows at different void

  2. Atypical radiation response of SCID cells

    NASA Astrophysics Data System (ADS)

    Chawapun, Nisa

    Murine SCID (severe combined immune deficiency) cells are well known for their defect in DNA double-strand break repair and in variable(diversity)joining [V(D)J] recombination due to a mutation in a catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). As a consequence, scid cells are hypersensitive to ionizing radiation. The present study showed that asynchronous populations of scid cells were about two-fold more sensitive than Balb/c with respect to cell killing and the defect in scid cells was corrected by complementation with human chromosome 8. Analysis of the survival of synchronized populations as a function of the cell cycle revealed that while scid cells were hypersensitive in all cell cycle phases compared to wild-type cells, this hypersensitivity is even more pronounced in G1 phase. The hypersensitivity reduced as the cells progressed into S phase suggested that homologous recombination repair plays a role. The results imply that there are at least two pathways for the repair of DSB DNA, consistent with a model previously proposed by others. The scid cells were also more sensitive to UVC light (254 nm) killing as compared to wild type cells by clonogenic survival. Using a host cell reactivation (HCR) assay to study the nucleotide excision repair (NER) which is the major repair pathway for UV-photoproducts, the results showed that NER in scid cells was not as efficient as CB- 17. This suggests that DNA-PK is involved in NER as well as non-homologous end-joining (NHEJ) DSB repair which is responsible for ionizing radiation sensitivity in scid cells. Repair in scid cells was not totally absent as shown by low dose rate sparing of cell killing after exposure to 137Cs ?-rays at dose rate of 0.6 cGy/h, 1.36 cGy/h, 6 cGy/h as compared to high dose rate at 171 cGy/min, although this phenomenon could be explained partly by proliferation. However, for radiation induced transformation, no significant dose rate effect was seen. A plot of transformation versus survival revealed that the transformation induction was inversely proportional to radiation dose rate. Lower dose rates were more effective in inducing transformation in scid cells. This finding could lead to the influence of cancer risk estimation in an irradiated population consisting of a subpopulation(s) with genetic disorders predisposing those individuals to cancer.

  3. Stenotrophomonas maltophilia with histopathological features mimicking cutaneous gamma/delta T-cell lymphoma.

    PubMed

    Kash, Natalie; Vin, Harina; Danialan, Richard; Prieto, Victor G; Duvic, Madeleine

    2015-01-01

    We report a case of cutaneous Stenotrophomonas maltophilia infection which presented with clinical and histopathological findings that mimicked a gamma/delta (??) T-cell lymphoma. In this case, tissue culture of the biopsy specimen was key to determining the diagnosis and allowing appropriate treatment with oral trimethoprim-sulfamethoxazole and topical silvadene. A prompt complete resolution of lesions was observed following antibiotic treatment, with no recurrence of disease over the last 5 years, supporting an infectious rather than malignant etiology. In our patient, radiation therapy was indicated based on the misdiagnosis of ?? T-cell lymphoma, which was supported both clinically and histopathologically. However, tissue culture in this case avoided unnecessary radiation exposure and highlights the role of tissue culture in the evaluation of the biopsy of an undiagnosed cutaneous lesion. PMID:25462188

  4. Application of whole-body personal TL dosemeters in mixed field beta-gamma radiation.

    PubMed

    Ciupek, K; Aksamit, D; Wo?oszczuk, K

    2014-11-01

    Application of whole-body personal TL dosemeters based on a high-sensitivity LiF:Mg,Cu,P (MCP-N) in mixed field beta-gamma radiation has been characterised. The measurements were carried out with (90)Sr/(90)Y, (85)Kr and (137)Cs point sources to calculate the energy response and linearity of the TLD response in a dose range of 0.1-30 mSv. From the result, calibration curves were obtained, enabling the readout of individual dose equivalent Hp(10) from gamma radiation and Hp(0.07) from beta radiation in mixed field beta-gamma. Limitation of the methodology and its application are presented and discussed. PMID:25009188

  5. SAS-2 observations of the high energy gamma radiation from the Vela region

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bignami, G. F.; Fichtel, C. E.; Kniffen, D. A.

    1974-01-01

    Data from a scan of the galactic plane by the SAS-B high energy gamma ray experiment in the region 250 deg smaller than 12 smaller than 290 deg show a statistically significant excess over the general radiation from the galactic plane for gamma radiation of energy larger than 100 MeV. If the enhanced gamma radiation results from interactions of cosmic rays with galactic matter, as the energy spectrum suggests, it seems reasonable to associate the enhancement with large scale galactic features, such as spiral arm segments in that direction, or with the region surrounding the Vela supernova remnant with which PSR 0833-45 is associated. If the excess is attributed to cosmic rays released from the supernova interacting with the interstellar matter in that region, than on the order of 3 x 10 to the 50th power ergs would have been released by that supernova in the form of cosmic rays.

  6. Secondary production of neutral pi-mesons and the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.

    1986-01-01

    Isobaric and scaling model predictions of the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior. This model is accordingly used, in conjuction with a scaling model representation at high energies, in a recalculation of the pi exp (0) gamma-radiation's contribution to the diffuse galactic gamma background; the cosmic ray-induced production of photons (whose energy exceeds 100 MeV) by such radiation occurs at a rate of 1.53 x 10 to the -25 photons/(s-H atom). These results are compared with previous calculations of this process as well as with COS-B observations of the diffuse galactic gamma-radiation.

  7. Gamma herpesviruses: pathogenesis of infection and cell signaling.

    PubMed

    Rajcáni, J; Kúdelová, M

    2003-01-01

    Altered cell signaling is the molecular basis for cell proliferation occurring in association with several gamma herpesvirus infections. Three gamma herpesviruses, namely EBV/HHV-4, KSHV/HHV-8 and the MHV-68 (and/or MHV-72) and their unusual cell-pirated gene products are discussed in this respect. The EBV, KSHV as well as the MHV DNA may persist lifelong in an episomal form in the host carrier cells (mainly in lymphocytes but also in macrophages, in non-hornifying squamous epithelium and/or in blood vessel endothelial cells). Under conditions of extremely limited transcription, the EBV-infected cells express EBNA1 (EB nuclear antigen 1), the KSHV infected cells express LANA1 (latent nuclear antigen 1), while the MHV DNA carrier cells express the latency-associated protein M2. With the full set of latency-associated proteins expressed, EBV carrier cells synthesize additional EBNAs and at least one LMP (latent membrane protein 1). The latent KSHV carrier cells, in addition to LANA1, may express a viral cyclin, a viral Fas-DD-like ICE inhibitor protein (vFLIP) and a virus-specific transformation protein called kaposin (K12). In MHV latency with a wide expression of latency-associated proteins, the carrier cells express a LANA analogue (ORF73), the M3 protein, the K3/IE (immediate early) proteins and M11/bcl-2 homologue proteins. During the period of limited gene expression, the latency-associated proteins serve mainly for the maintenance of the latent episomal DNA (a typical example is EBNA1). In contrast, during latency with a broader spectrum gene expression, the virus-encoded products activate transcription of otherwise silenced cellular genes, which leads to the synthesis of enzymes capable of promoting not only viral but also cellular DNA replication. Thus, the latency-associated proteins block apoptosis and drive host cells towards division and immortalization. Proliferation of hemopoetic cells, which had become gamma herpesvirus DNA carriers, can be initiated and strongly enhanced in the presence of inflammatory cytokines and by virus-encoded analogues of interleukins, chemokines and IFN regulator proteins. At early stages of tumor formation, many proliferating hemopoetic and/or endothelium cells, which had became transcriptionally active under the influence of chemokines and cytokines, may not yet be infected. In contrast, at later stages of oncogenesis, the virus-encoded proteins, inducing false signaling and activating the proliferation pathways, bring the previously infected cells into full transformation burst. PMID:12879740

  8. Enrichment of magnetic alignment stimulated by {gamma}-radiation in core-shell type nanoparticle Mn-Zn ferrite

    SciTech Connect

    Naik, P. P.; Tangsali, R. B. [Department of Physics, Goa University, Taleigao Plateau, Goa-403206 (India); Sonaye, B.; Sugur, S. [Goa Medical College, Bambolim, Goa (India)

    2013-02-05

    Core shell type nanoparticle Mn{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} systems with x=0.55, 0.65 and 0.75 were prepared using autocombustion method. The systems were characterized using tools like XRD and IR for structure confirmation. Magnetic parameter measurements like Saturation magnetization and coercivity were obtained from hysteresis loop which exhibited a symmetry shift due to core shell nature of the nanoparticles. Nanoparticles of particle size between 21.2nm to 25.7nm were found to show 20 percent shrinkage after being radiated by the {gamma}-radiation. This is due to variation in the cation distribution which also affects the cell volume of the cubic cell. Lattice constant reduction observed is reflected in the magnetic properties of the samples. A considerable hike in the saturation magnetization of the samples was observed due to enrichment of magnetic alignment in the magnetic core of the particles. Samples under investigation were irradiated with gamma radiation from Co{sup 60} source for different time intervals.

  9. Effects of gamma rays, ultraviolet radiation, sunlight, microwaves and electromagnetic fields on gene expression mediated by human immunodeficiency virus promoter

    SciTech Connect

    Libertin, C.R.; Woloschak, G.E. [Argonne National Lab., IL (United States)]|[Loyola Univ. Medical Center, Maywood, IL (United States); Panozzo, J.; Groh, K.R.; Chang-Liu, Chin-Mei; Schreck, S. [Argonne National Lab., IL (United States)

    1994-10-01

    Previous work by our group and others has shown the modulation of human immunodeficiency virus (HIV) promoter or long terminal repeat (LTR) after exposure to neutrons and ultraviolet radiations. Using HeLa cells stably transfected with a construct containing the chloramphenicol acetyl transferase (CAT) gene, the transcription of which is mediated by the HIV-LTR, we designed experiments to examine the effects of exposure to different types of radiation (such as {gamma} rays, ultraviolet and sunlight irradiations, electromagnetic fields and microwaves) in HIV-LTR-driven expression of CAT. These results demonstrated ultraviolet-light-induced transcription from the HIV promoter, as has been shown by others. Exposure to other DNA-damaging agents such as {gamma} rays and sunlight (with limited exposures) had no significant effect on transcription mediated by HIV-LTR, suggesting that induction of HIV is not mediated by just any type of DNA damage but rather may require specific types of DNA damage. Microwaves did not cause cell killing when cells in culture were exposed in high volumes of medium, and the same cells showed no changes in expression. When microwave exposure was carried out in low volumes of medium (so that excessive heat was generated) induction of HIV-LTR transcription (as assayed by CAT activity) was evident. Electromagnetic field exposures had no effect on expression of HIV-LTR. These results demonstrate that not all types of radiation and not all DNA-damaging agents are capable of inducing HIV. We hypothesize that induction of HIV transcription may be mediated by several different signals exposure to radiation. 22 refs., 8 figs.

  10. Radiation effects of helium ions, neutrons, and gamma-rays on photo-stimulated luminescence

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hisao; Shibata, Hiromi; Eguchi, Hoshio; Sato, Masanori; Etoh, Masahiro; Takebe, Masahiro; Abe, Ken

    1998-02-01

    A photo-stimulated luminescent (PSL) material, BaFBr 0.85I 0.15 : Eu 2+, was irradiated by 1 and 2 MeV He + ions. The radiation effects were compared with that of fission neutrons, 137Cs and 60Co gamma-rays. Deterioration of PSL signals was measured as a function of total fluence for ions and neutrons or dose for gamma-rays. Relative deteriorations for neutrons and gamma-rays were compared with that of 1 MeV He + ion irradiation. A self-generation of PSL signals depending on fluence and storage time was observed.

  11. Lunar radiation environment: a study by using Kaguya gamma-ray spectrometer and Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Kobayashi, Shingo; Hayatsu, Kanako; Uchihori, Yukio; Hareyama, Makoto; Hasebe, Nobuyuki; Fujibayashi, Yukari

    2012-07-01

    We have continued to improve the estimation of radiation dose on the Moon based on observation by remote sensing and calculation of the transportation of cosmic-ray particles in the lunar materials in order to provide basic data for a future manned lunar exploration. On the lunar surface, the dose of primary galactic cosmic rays (pGCR) is the most significant and the contributions of neutrons and gamma rays are relatively small and are approximately 10% and 1% of that of pGCR, respectively. However, these percentages are changed by use of thick shieldings and also geographical feature of the lunar surface, such as margin of a huge boulder, bottom of a pit, inside of a possible lava tube. In this case, the dose by pGCRs is moderated and the contributions of neutrons and gamma rays relatively increase. Here, we show the recent estimation of spatial variation of the lunar dose due to gamma ray and neutrons measured by Kaguya gamma-ray spectrometer. The energy spectrum of gamma rays from the lunar surface are precisely measured by a germanium (Ge) gamma-ray spectrometer onboard the Japanese lunar orbiter (Kaguya/SELENE). The flux of fast neutrons from the lunar surface was also measured by detecting the characteristic gamma rays due to the neutron inelastic reaction with the Ge of the spectrometer, that is 72Ge(n, n'g)72Ge. The estimation of radiation dose on the Moon based on Monte Carlo simulation will also be presented.

  12. Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system

    DOEpatents

    Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

    2013-02-12

    A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

  13. Search for Bremsstrahlung radiation in quasi-free n p --> n p gamma reactions

    E-print Network

    Przerwa, J; Budzanowski, A; Czyzykiewicz, R; Grzonka, D; Janusz, M; Jarczyk, L; Kamys, B; Khoukaz, A; Kilian, K; Klaja, P; Lang, N; Moskal, P; Oelert, W; Piskor-Ignatowicz, C; Rozek, T; Santo, R; Sefzick, T; Siemaszko, M; Smyrski, J; Täschner, A; Winter, P; Wolke, M; Wüstner, P; Zipper, W

    2004-01-01

    Due to the high sensitivity of the N N --> N N gamma reaction to the nucleon-nucleon potential, Bremsstrahlung radiation is used as a tool to investigate details of the nucleon-nucleon interaction. Such investigations can be performed at the cooler synchrotron COSY in the Research Centre Juelich, by dint of the COSY-11 detection system. The results of the identification of Bremsstrahlung radiation emitted via the d p --> d p gamma reaction in data taken with a proton target and a deuteron beam are presented and discussed.

  14. Search for Bremsstrahlung radiation in quasi-free n p --> n p gamma reactions

    E-print Network

    J. Przerwa; H. -H. Adam; A. Budzanowski; R. Czyzykiewicz; D. Grzonka; M. Janusz; L. Jarczyk; B. Kamys; A. Khoukaz; K. Kilian; P. Klaja; N. Lang; P. Moskal; W. Oelert; C. Piskor-Ignatowicz; T. Rozek; R. Santo; T. Sefzick; M. Siemaszko; J. Smyrski; A. Taeschner; P. Winter; M. Wolke; P. Wuestner; W. Zipper

    2004-07-21

    Due to the high sensitivity of the N N --> N N gamma reaction to the nucleon-nucleon potential, Bremsstrahlung radiation is used as a tool to investigate details of the nucleon-nucleon interaction. Such investigations can be performed at the cooler synchrotron COSY in the Research Centre Juelich, by dint of the COSY-11 detection system. The results of the identification of Bremsstrahlung radiation emitted via the d p --> d p gamma reaction in data taken with a proton target and a deuteron beam are presented and discussed.

  15. A biotechnological project with a gamma radiation source of 100,000 Ci

    NASA Astrophysics Data System (ADS)

    Lombardo, J. H.; Smolko, E. E.

    A project for the production of radiovaccines and other bio-medical products is presented which includes a radiation facility provided with a gamma ray source equivalent to 100,000 Ci of Co-60. The whole process incorporates novel basic features in virus production and inactivation steps. The former is carried out in animals previously subjected to immunodepression through electromagnetic radiation. The later is obtained at low temperatures by using either electromagnetic or particle radiations. A vaccine manufacture process is shown to illustrate the utilization of ionizing radiations to obtain a foot and mouth disease virus (FMDV) vaccine with good antigenic quality and low cost.

  16. Preparation of polyester/gypsum/composite using gamma radiation, and its radiation stability

    NASA Astrophysics Data System (ADS)

    Ajji, Zaki

    2005-06-01

    Composites based on pure gypsum and polyester-styrene resin have been prepared using various doses of gamma radiation. Some physical properties of the prepared composites and the influence of irradiation dose on it have been studied as: compression strength, hardness, thermal decomposition temperature in nitrogen or oxygen, and the change in weight in aqueous solutions with different pH values. The glass transition temperature of the pure polymer and the composites increases with increasing the irradiation dose up to a plateau, and the glass transition temperature of the pure polymer is lower than that of the composites. The irradiation dose does not seem to affect the decomposition temperature of the pure polymer or the composites significantly and the decomposition temperature in presence of nitrogen is higher than that in presence of oxygen. Increasing the irradiation dose leads to an enhancement of the compression strength of the pure polymer and the prepared composites; the hardness of the pure polymer and the composites seems to be constant versus the irradiation dose. Soaking experiments show that the weight of composites does not change in distilled and alkaline medium, but there is a limited decrease in acidic medium of about 3% after 1560 h.

  17. The TP53 dependence of radiation-induced chromosome instability in human lymphoblastoid cells

    NASA Technical Reports Server (NTRS)

    Schwartz, Jeffrey L.; Jordan, Robert; Evans, Helen H.; Lenarczyk, Marek; Liber, Howard

    2003-01-01

    The dose and TP53 dependence for the induction of chromosome instability were examined in cells of three human lymphoblastoid cell lines derived from WIL2 cells: TK6, a TP53-normal cell line, NH32, a TP53-knockout created from TK6, and WTK1, a WIL2-derived cell line that spontaneously developed a TP53 mutation. Cells of each cell line were exposed to (137)Cs gamma rays, and then surviving clones were isolated and expanded in culture for approximately 35 generations before the frequency and characteristics of the instability were analyzed. The presence of dicentric chromosomes, formed by end-to-end fusions, served as a marker of chromosomal instability. Unexposed TK6 cells had low levels of chromosomal instability (0.002 +/- 0.001 dicentrics/cell). Exposure of TK6 cells to doses as low as 5 cGy gamma rays increased chromosome instability levels nearly 10-fold to 0.019 +/- 0.008 dicentrics/cell. There was no further increase in instability levels beyond 5 cGy. In contrast to TK6 cells, unexposed cultures of WTK1 and NH32 cells had much higher levels of chromosome instability of 0.034 +/- 0.007 and 0.041 +/- 0.009, respectively, but showed little if any effect of radiation on levels of chromosome instability. The results suggest that radiation exposure alters the normal TP53-dependent cell cycle checkpoint controls that recognize alterations in telomere structure and activate apoptosis.

  18. Modulation of gene expression in Syrian hamster embryo cells following ionizing radiation.

    PubMed

    Woloschak, G E; Chang-Liu, C M; Jones, P S; Jones, C A

    1990-01-15

    We examined the modulation of gene expression in Syrian hamster embryo (SHE) cells at various times following exposure to low doses of ionizing radiation. Early passage SHE cells were irradiated in plateau phase (greater than 95% G0-G1 cells) with 21-cGy fission-spectrum neutrons, 75-cGy X-rays, or 90-cGy gamma-rays, none of which induced more than 10% loss in cell viability. RNA harvested at various times after exposure was examined for levels of particular RNA species by dot blot and Northern blot hybridizations. Levels of beta-actin-specific RNA decreased within 15 min after exposure of the cells. The kinetics of repression of beta-actin mRNA were similar for all qualities of radiation (X-rays, gamma-rays, and neutrons) for 12 h post-irradiation. Within 1 h after neutron exposure (21 cGy), we observed a decrease in accumulation of RNA species (relative to RNA from nonirradiated cells) encoding the enzyme ornithine decarboxylase; this decrease continued for up to 12 h. Similar results were obtained with gamma- and X-rays. RNA encoding interleukin 1, however, was induced by 3 h after neutron irradiation but reduced to background levels by 7 h. Amounts of rRNA remained constant in all experiments, although total transcription on a per cell basis was reduced within 15 min following irradiation and did not return to normal until 7 h post-irradiation. No alterations, relative to untreated control cells, in overall cell viability or the rate of cell cycle progression were observed in cells either immediately or within 24 h post-irradiation. Our results demonstrate modulation of specific genes following low-dose irradiation. In addition, our findings suggest that some molecular responses to different qualities of ionizing radiation (X-rays, gamma-rays, and neutrons) may be similar. PMID:2295074

  19. Activation of a c-K-ras oncogene by somatic mutation in mouse lymphomas induced by gamma radiation

    SciTech Connect

    Guerrero, I.; Villasante, A.; Corces, V.; Pellicer, A.

    1984-09-14

    Mouse tumors induced by gamma radiation are a useful model system for oncogenesis. DNA from such tumors contains an activated K-ras oncogene that can transform NIH 3T3 cells. This report describes the cloning of a fragment of the mouse K-ras oncogene containing the first exon from both a transformant in rat-2 cells and the brain of the same mouse that developed the tumor. Hybrid constructs containing one of the two pieces were made and only the plasmid including the first exon from the transformant gave rise to foci in NIH 3T3 cells. There was only a single base difference (G----A) in the exonic sequence, which changed glycine to aspartic acid in the transformant. By use of a synthetic oligonucleotide the presence of the mutation was demonstrated in the original tumor, ruling out modifications during DNA-mediated gene transfer and indicating that the alteration was present in the thymic lymphoma but absent from other nonmalignant tissue. The results are compatible with gamma radiation being a source of point mutations.

  20. Immunoglobulin gamma 2b transgenes inhibit heavy chain gene rearrangement, but cannot promote B cell development

    PubMed Central

    1993-01-01

    Transgenic mice with a gamma 2b transgene were produced to investigate whether gamma 2b can replace mu in the development of B lymphocytes. Transgenic gamma 2b is present on the surface of B cells. Young transgenic mice have a dramatic decrease in B cell numbers, however, older mice have almost normal B cell numbers. Strikingly, all gamma 2b- expressing B cells in the spleen also express mu. The same is true for mice with a hybrid transgene in which the mu transmembrane and intracytoplasmic sequences replace those of gamma 2b (gamma 2b-mumem). The B cell defect is not due to toxicity of gamma 2b since crosses between gamma 2b transgenic and mu transgenic mice have normal numbers of B cells. Presence of the gamma 2b transgene strongly enhances the feedback inhibition of endogenous heavy chain gene rearrangement. Light chain genes are expressed normally, and the early expression of transgenic light chains does not improve B cell maturation. When the endogenous mu locus is inactivated, B cells do not develop at all in gamma 2b transgenic mice. The data suggest that gamma 2b cannot replace mu in promoting the developmental maturation of B cells, but that it can cause feedback inhibition of heavy chain gene rearrangement. Thus, the signals for heavy chain feedback and B cell maturation appear to be different. PMID:8245779

  1. Attenuation of VHE Gamma Rays by the Milky Way Interstellar Radiation Field

    SciTech Connect

    Moskalenko, Igor V.; /Stanford U., HEPL; Porter, Troy A.; /Louisiana State U.; Strong, Andrew W.; /Garching, Max Planck Inst., MPE

    2006-04-19

    The attenuation of very high energy gamma rays by pair production on the Galactic interstellar radiation field has long been thought of as negligible. However, a new calculation of the interstellar radiation field consistent with multi-wavelength observations by DIRBE and FIRAS indicates that the energy density of the Galactic interstellar radiation field is higher, particularly in the Galactic center, than previously thought. We have made a calculation of the attenuation of very high energy gamma rays in the Galaxy using this new interstellar radiation field which takes into account its nonuniform spatial and angular distributions. We find that the maximum attenuation occurs around 100 TeV at the level of about 25% for sources located at the Galactic center, and is important for both Galactic and extragalactic sources.

  2. Role of inducible heat shock protein 70 in radiation-induced cell death

    PubMed Central

    Lee, Su-Jae; Choi, Sun-Ah; Lee, Kang-Hyun; Chung, Hee-Yong; Kim, Tae-Hwan; Cho, Chul-Koo; Lee, Yun-Sil

    2001-01-01

    We previously demonstrated the protective effect of inducible heat shock protein 70 (Hsp70) against gamma radiation. Herein, we extend our studies on the possible role of Hsp70 to ionizing radiation-induced cell cycle regulation. The growth rate of inducible hsp70-transfected cells was 2–3 hours slower than that of control cells. Flow cytometric analysis of cells at G1 phase synchronized by serum starvation also showed the growth delay in the Hsp70-overexpressing cells. In addition, reduced cyclin D1 and Cdc2 levels and increased dephosphorylated phosphoretinoblastoma (pRb) were observed in inducible hsp70-transfected cells, which were probably responsible for the reduction of cell growth. To find out if inducible Hsp70-mediated growth delay affected radiation-induced cell cycle regulation, flow cytometric and molecular analyses of cell cycle regulatory proteins and their kinase were performed. The radiation-induced G2/M arrest was found to be inhibited by Hsp70 overexpression and reduced p21Waf induction and its kinase activity by radiation in the Hsp70-transfected cells. In addition, radiation-induced cyclin A or B1 expressions together with their kinase activities were also inhibited by inducible Hsp70, which represented reduced mitotic cell death. Indeed, hsp70 transfectants showed less induction of radiation-induced apoptosis. When treated with nocodazole, radiation-induced mitotic arrest was inhibited by inducible Hsp70. These results strongly suggested that inducible Hsp70 modified growth delay (increased G1 phase) and reduced G2/M phase arrest, subsequently resulting in inhibition of radiation-induced cell death. PMID:11599569

  3. Gamma radiation used as hygienization technique for foods does not induce viable but non-culturable state (VBNC) in Salmonella enterica subsp. enterica serovar Typhimurium.

    PubMed

    Saroj, Sunil; Shashidhar, R; Bandekar, Jayant

    2009-10-01

    Gamma radiation has been widely used for hygienization of food products. Whether gamma radiation stress induces VBNC state in Salmonella is of great concern. Therefore, the study was carried out to determine whether gamma radiation exposure induces VBNC state in Salmonella enterica subsp. enterica serovar Typhimurium (S. typhimurium). The parameters tested were culturability on agar medium, transcriptional activity by RT-PCR, cytoplasmic membrane integrity, and direct viable count using LIVE/DEAD BacLight bacterial viability kit. The LIVE/DEAD BacLight counts for S. typhimurium cells treated with 0.5 and 1.0 kGy radiation dose were 0.8 and 0.1% of the control, respectively. Plate counts for S. typhimurium cells treated with 0.5 and 1.0 kGy radiation dose were 0.7 and 0.05% of the control, respectively. No viable cells of S. typhimurium were detected by both plate count and LIVE/DEAD BacLight after radiation treatment with 2 kGy. No transcriptional activity was detected in cells treated with 2 kGy radiation dose. If there were VBNC cells present, then significant differences in the counts between the LIVE/DEAD BacLight microscopic counts and plate agar counts must be observed. No significant difference (P > 0.05) in the counts were observed. Thus, it can be concluded that treatment with 2 kGy results in complete killing and does not induce VBNC state in S. typhimurium. PMID:19641961

  4. Radiation detection system for portable gamma-ray spectroscopy

    DOEpatents

    Rowland, Mark S. (Alamo, CA); Howard, Douglas E. (Livermore, CA); Wong, James L. (Dublin, CA); Jessup, James L. (Tracy, CA); Bianchini, Greg M. (Livermore, CA); Miller, Wayne O. (Livermore, CA)

    2006-06-20

    A portable gamma ray detection apparatus having a gamma ray detector encapsulated by a compact isolation structure having at least two volumetrically-nested enclosures where at least one is a thermal shield. The enclosures are suspension-mounted to each other to successively encapsulate the detector without structural penetrations through the thermal shields. A low power cooler is also provided capable of cooling the detector to cryogenic temperatures without consuming cryogens, due to the heat load reduction by the isolation structure and the reduction in the power requirements of the cooler. The apparatus also includes a lightweight portable power source for supplying power to the apparatus, including to the cooler and the processing means, and reducing the weight of the apparatus to enable handheld operation or toting on a user's person.

  5. Effects of gamma irradiation on the radiation-resistant bacteria and polyphenol oxidase activity in fresh kale juice

    NASA Astrophysics Data System (ADS)

    Kim, Dongho; Song, Hyunpa; Lim, Sangyong; Yun, Hyejeong; Chung, Jinwoo

    2007-07-01

    Gamma radiation was performed to prolong the shelf life of natural kale juice. The total aerobic bacteria in fresh kale juice, prepared by a general kitchen process, was detected in the range of 10 6 cfu/ml, and about 10 2 cfu/ml of the bacteria survived in the juice in spite of gamma irradiation treatment with a dose of 5 kGy. Two typical radiation-resistant bacteria, Bacillus megaterium and Exiguobacterium acetylicum were isolated and identified from the 5 kGy-irradiated kale juices. The D10 values of the vegetative cell and endospore of the B. megaterium in peptone water were 0.63±0.05 and 1.52±0.05 kGy, respectively. The D10 value of the E. acetylicum was calculated as 0.65±0.06 kGy. In the inoculation test, the growth of the surviving B. megaterium and E. acetylicum in the 3-5 kGy-irradiated kale juice retarded and/or decreased significantly during a 3 d post-irradiation storage period. However, there were no significant differences in the residual polyphenol oxidase activity and browning index between the nonirradiated control and the gamma irradiated kale juice during a post-irradiation period.

  6. Persistence of gamma-H2AX and 53BP1 foci in proliferating and nonproliferating human mammary epithelial cells after exposure to gamma-rays or iron ions

    SciTech Connect

    Groesser, Torsten; Chang, Hang; Fontenay, Gerald; Chen, James; Costes, Sylvain V.; Barcellos-Hoff, Mary Helen; Parvin, Bahram; Rydberg, Bjorn

    2010-12-22

    To investigate {gamma}-H2AX (phosphorylated histone H2AX) and 53BP1 (tumour protein 53 binding protein No. 1) foci formation and removal in proliferating and non-proliferating human mammary epithelial cells (HMEC) after exposure to sparsely and densely ionizing radiation under different cell culture conditions. HMEC cells were grown either as monolayers (2D) or in extracellular matrix to allow the formation of acinar structures in vitro (3D). Foci numbers were quantified by image analysis at various time points after exposure. Our results reveal that in non-proliferating cells under 2D and 3D cell culture conditions, iron-ion induced {gamma}-H2AX foci were still present at 72 h after exposure, although 53BP1 foci returned to control levels at 48 h. In contrast in proliferating HMEC, both {gamma}-H2AX and 53BP1 foci decreased to control levels during the 24-48 h time interval after irradiation under 2D conditions. Foci numbers decreased faster after {gamma}-ray irradiation and returned to control levels by 12 h regardless of marker, cell proliferation status, and cell culture condition. Conclusions: The disappearance of radiation induced {gamma}-H2AX and 53BP1 foci in HMEC have different dynamics that depend on radiation quality and proliferation status. Notably, the general patterns do not depend on the cell culture condition (2D versus 3D). We speculate that the persistent {gamma}-H2AX foci in iron-ion irradiated non-proliferating cells could be due to limited availability of double strand break (DSB) repair pathways in G0/G1-phase, or that repair of complex DSB requires replication or chromatin remodeling.

  7. Efficient modeling of Compton diode gamma radiation detectors

    Microsoft Academic Search

    D. R. Drumm; J. J. Hohlfelder; J. D. Kotulski; G. J. Scrivner; G. S. Mills; T. J. Tanaka

    1991-01-01

    The CEPXS\\/ONELD code package proves to be significantly more efficient than electron Monte Carlo for computing the spherical Compton diode response to gamma irradiation, requiring only minutes instead of hours of Cray computer time. The adjoint capability of CEPXS\\/ONELD allows the complete energy-angle response of a Compton diode to be determined with a single transport calculation. The method is a

  8. Efficient modeling of Compton diode gamma radiation detectors

    Microsoft Academic Search

    C. R. Drumm; J. J. Hohlfelder; J. D. Kotulski; G. J. Scrivner; G. S. MillsandT; T. J. Tanaka

    1992-01-01

    The CEPXS\\/ONELD code package proved to be significantly more efficient than electron Monte Carlo for computing spherical Compton diode response to gamma irradiation. The authors review the mechanism responsible for the production of electric currents in Compton diodes, describe the calculation method, and present results for a few representative Compton diodes. The adjoint capability of CEPXS\\/ONELD allows the complete energy-angle

  9. Zener diodes for gamma-ray radiation dosimetry

    Microsoft Academic Search

    Shigeki Nakamura; Shinichi Okamoto

    1995-01-01

    The fundamental properties of Zener diodes and junction field-effect transistors have been studied to use them as a relative dose monitor or a radiation-damage monitor. The response observed at liquid nitrogen temperature, i.e., radiation-induced change in the breakdown voltage of the Zener diode, or change in the breakdown voltage of the pn junction between the gate and the channel (or

  10. Breeding biology of Tree Swallows and House Wrens in a gradient of gamma radiation

    Microsoft Academic Search

    R. Zach; K. R. Mayoh

    1982-01-01

    In a gradient of gamma radiation from 38.7 mC kg⁻¹.d⁻¹ to background levels of 0.05 ..mu..C. kg⁻¹ . d⁻¹ to background levels of 0.05 ..mu..C . kg⁻¹ . d⁻¹, Tree Swallows (Iridoprocne bicolor) and House Wrens (Troglodytes aedon) avoided nesting in areas of high radiation. Nest boxes selected by swallows and wrens had a mean exposure rate of only 9.3

  11. Effect of /sup 60/Co /gamma/-radiation on aqueous solutions of acrylamide

    SciTech Connect

    Zhestkova, T.P.; Misevich, B.S.; Kotov, A.V.

    1988-07-01

    Data were obtained on the dependence of the index of refraction (ir) of aqueous solutions of acrylamide on the absorbed dose of /sup 60/Co /gamma/-radiation. The calculated data on the dependence of ir on the degree of polymerization are reported. Using calculations of polymer models and the IR spectra, it was shown that the increase in the ir of the irradiated solution is due to oxidative processes which take place in the polymer formed under the effect of the radiation.

  12. Gallium arsenide solar cell radiation damage study

    Microsoft Academic Search

    R. H. Maurer; G. A. Herbert; J. D. Kinnison; A. Meulenberg

    1989-01-01

    An analysis has been made of electrons and proton damaged GaAs solar cells suitable for use in space. The authors find that although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I - V analysis model shows that electrons damage the bulk of

  13. Gallium arsenide solar cell radiation damage study

    Microsoft Academic Search

    R. H. Maurer; G. A. Herbert; J. D. Kinnison; A. Meulenberg

    1989-01-01

    A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the

  14. Radiation degradation of solar cell arrays

    NASA Technical Reports Server (NTRS)

    Hill, C. W.

    1975-01-01

    A method of incorporating a detailed solar cell radiation degradation model into a convenient computational scheme suitable for the solar electric propulsion system is outlined. The study shows that several existing codes may be applied in sequence to solve the problem.

  15. Gallium Arsenide solar cell radiation damage experiment

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

    1991-01-01

    Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

  16. Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation

    NASA Technical Reports Server (NTRS)

    Plaza-Rosado, Heriberto

    1991-01-01

    Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron distribution generated by the BRYNTRN and HZETRN transport codes for Galactic Cosmic Rays (GCR) at solar minimum conditions and intense solar flares in space systems components. The gamma dose rates for soft tissue are calculated for water and aluminum space vehicle slab shields considering volumetric source self-attenuation and exponential buildup factors. In the case of the lunar habitat with regolith shielding, a completely exposed spherical habitat was assumed for mathematical convenience and conservative calculations. Activation analysis of the food supply used as radiation shielding is presented for four selected nutrients: potassium, calcium, sodium, and phosphorus. Radioactive isotopes that could represent a health hazard if ingested are identified and their concentrations are identified. For nutrients soluble in water, it was found that all induced radioactivity was below the accepted maximum permissible concentrations.

  17. Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation

    NASA Astrophysics Data System (ADS)

    Plaza-Rosado, Heriberto

    1991-09-01

    Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron distribution generated by the BRYNTRN and HZETRN transport codes for Galactic Cosmic Rays (GCR) at solar minimum conditions and intense solar flares in space systems components. The gamma dose rates for soft tissue are calculated for water and aluminum space vehicle slab shields considering volumetric source self-attenuation and exponential buildup factors. In the case of the lunar habitat with regolith shielding, a completely exposed spherical habitat was assumed for mathematical convenience and conservative calculations. Activation analysis of the food supply used as radiation shielding is presented for four selected nutrients: potassium, calcium, sodium, and phosphorus. Radioactive isotopes that could represent a health hazard if ingested are identified and their concentrations are identified. For nutrients soluble in water, it was found that all induced radioactivity was below the accepted maximum permissible concentrations.

  18. Papain incorporated chitin dressings for wound debridement sterilized by gamma radiation

    NASA Astrophysics Data System (ADS)

    Singh, Durgeshwer; Singh, Rita

    2012-11-01

    Wound debridement is essential for the removal of necrotic or nonviable tissue from the wound surface to create an environment conducive to healing. Nonsurgical enzymatic debridement is an attractive method due to its effectiveness and ease of use. Papain is a proteolytic enzyme derived from the fruit of Carica papaya and is capable of breaking down a variety of necrotic tissue substrates. The present study was focused on the use of gamma radiation for sterilization of papain dressing with wound debriding activity. Membranes with papain were prepared using 0.5% chitin in lithium chloride/dimethylacetamide solvent and sterilized by gamma radiation. Fluid absorption capacity of chitin-papain membranes without glycerol was 14.30±6.57% in 6 h. Incorporation of glycerol resulted in significant (p<0.001) increase in the absorption capacity. Moisture vapour transmission rate of the membranes was 4285.77±455.61 g/m2/24 h at 24 h. Gamma irradiation at 25 kGy was found suitable for sterilization of the dressings. Infrared (IR) spectral scanning has shown that papain was stable on gamma irradiation at 25-35 kGy. The irradiated chitin-papain membranes were impermeable to different bacterial strains and also exhibited strong bactericidal action against both Gram-positive and Gram-negative bacteria. The fluid handling characteristics and the antimicrobial properties of chitin-papain membranes sterilized by gamma radiation were found suitable for use as wound dressing with debriding activity.

  19. 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)

  20. Prediction of radiation dosimetry in patients with thyroid cancer using a Gamma camera

    Microsoft Academic Search

    G. L. De Nardo; D. J. Macey; S. J. De Nardo; D. A. Adams

    1985-01-01

    Radioiodine in the thyroid or cervical metastases, and therefore radiation dosimetry, can be determined using a probe and phantom. This approach is not ideal for quantitating radioiodine and dosimetry for sites elsewhere in the body. The authors have studied the use of gamma camera methods in association with I-123 to predict the distribution of I-131 and its dosimetry in 3

  1. The production and composition of rat sebum is unaffected by 3 Gy gamma radiation

    PubMed Central

    Lanz, Christian; Ledermann, Monika; Slavík, Josef; Idle, Jeffrey R.

    2013-01-01

    Purpose The aim of this work was to use metabolomics to evaluate sebum as a source of biomarkers for gamma-radiation exposure in the rat, and potentially in man. Proof of concept of radiation metabolomics was previously demonstrated in both mouse and rat urine, from the radiation dose- and time-dependent excretion of a set of urinary biomarkers. Materials and methods Rats were gamma-irradiated (3 Gy) or sham irradiated and groups of rats were euthanised at 1 h or 24 h post-irradiation. Sebum was collected by multiple washings of the carcasses with acetone. Nonpolar lipids were extracted, methylated, separated and quantitated using gas chromatography-mass spectrometry (GCMS). Metabolomic analysis of the GCMS data was performed using both orthogonal projection to latent structures-discriminant analysis and random forests machine learning algorithm. Results Irradiation did not alter sebum production. A total of 35 lipids were identified in rat sebum, 29 fatty acids, five fatty aldehydes, and cholesterol. Metabolomics showed that three fatty acids, palmitic, 2-hydroxypalmitic, and stearic acids were potential biomarkers. Sebaceous palmitic acid was marginally statistically significantly elevated (7.5–8.4%) at 24 h post-irradiation. Conclusions Rat sebaceous gland appears refractory to 3 Gy gamma-irradiation. Unfortunately, collection of sebum shortly after gamma-irradiation is unlikely to form the basis of high-throughput non-invasive radiation biodosimetry in man. PMID:21158499

  2. An integrated systems approach for understanding cellular responses to gamma radiation

    Microsoft Academic Search

    Kenia Whitehead; Adrienne Kish; Min Pan; Amardeep Kaur; David J Reiss; Nichole King; Laura Hohmann; Jocelyne DiRuggiero; Nitin S Baliga

    2006-01-01

    Cellular response to stress entails complex mRNA and protein abundance changes, which translate into physiological adjustments to maintain homeostasis as well as to repair and minimize damage to cellular components. We have characterized the response of the halophilic archaeon Halobacterium salinarum NRC-1 to 60Co ionizing gamma radiation in an effort to understand the correlation between genetic information processing and physiological

  3. Gamma-ray dose assessment after the 1994 radiation accident in Kiisa (Estonia): Preliminary results

    Microsoft Academic Search

    G. Hütt; L. Brodski; V. Polyakov

    1996-01-01

    Dose reconstruction using thermoluminescence (TL) of quartz, extracted from the ceramic plant pots, and using EPR of the sugar samples, was performed after the 1994 radiation accident in the village Kiisa (Estonai). A gamma-ray source 137Cs was located during approx. 28 days in one of the village dwelling houses. On the basis of preliminary results, some important details of the

  4. Gamma radiation inactivation of non-0157:H7 shiga-toxin producing Escherichia coli in foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Non-O157:H7 serovars of shiga-toxin producing Escherichia coli are emerging foodborne pathogens that have been associated with illness outbreaks and food product recalls on a global basis. Ionizing (gamma) radiation is a nonthermal food safety intervention technology that has been approved for use i...

  5. Gamma Radiation Induced Oxidation and Tocopherols Decrease in In-Shell, Peeled and Blanched Peanuts

    PubMed Central

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D’Arce, Marisa Aparecida Bismara; de Alencar, Severino Matias; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    In-shell, peeled and blanched peanut samples were characterized in relation to proximate composition and fatty acid profile. No difference was found in relation to its proximate composition. The three major fatty acids were palmitic acid, oleic acid, and linoleic acid. In order to investigate irradiation and storage effects, peanut samples were submitted to doses of 0.0, 5.0, 7.5 or 10.0 kGy, stored for six months at room temperature and monitored every three months. Peanuts responded differently to irradiation, particularly with regards to tocopherol contents, primary and secondary oxidation products and oil stability index. Induction periods and tocopherol contents were negatively correlated with irradiation doses and decreased moderately during storage. ?-Tocopherol was the most gamma radiation sensitive and peeled samples were the most affected. A positive correlation was found among tocopherol contents and the induction period of the oils extracted from irradiated samples. Gamma radiation and storage time increased oxidation compounds production. If gamma radiation is considered an alternative for industrial scale peanut conservation, in-shell samples are the best feedstock. For the best of our knowledge this is the first article with such results; this way it may be helpful as basis for future studies on gamma radiation of in-shell crops. PMID:22489128

  6. Gamma radiation induced oxidation and tocopherols decrease in in-shell, peeled and blanched peanuts.

    PubMed

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D'Arce, Marisa Aparecida Bismara; de Alencar, Severino Matias; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    In-shell, peeled and blanched peanut samples were characterized in relation to proximate composition and fatty acid profile. No difference was found in relation to its proximate composition. The three major fatty acids were palmitic acid, oleic acid, and linoleic acid. In order to investigate irradiation and storage effects, peanut samples were submitted to doses of 0.0, 5.0, 7.5 or 10.0 kGy, stored for six months at room temperature and monitored every three months. Peanuts responded differently to irradiation, particularly with regards to tocopherol contents, primary and secondary oxidation products and oil stability index. Induction periods and tocopherol contents were negatively correlated with irradiation doses and decreased moderately during storage. ?-Tocopherol was the most gamma radiation sensitive and peeled samples were the most affected. A positive correlation was found among tocopherol contents and the induction period of the oils extracted from irradiated samples. Gamma radiation and storage time increased oxidation compounds production. If gamma radiation is considered an alternative for industrial scale peanut conservation, in-shell samples are the best feedstock. For the best of our knowledge this is the first article with such results; this way it may be helpful as basis for future studies on gamma radiation of in-shell crops. PMID:22489128

  7. Radiative decay Y(4260) -> X(3872) + gamma involving hadronic molecular and charmonium components

    E-print Network

    Yubing Dong; Amand Faessler; Thomas Gutsche; Valery E. Lyubovitskij

    2014-10-29

    We apply a phenomenological Lagrangian approach to the radiative decay Y(4260) -> X(3872) + gamma. The Y(4260) and X(3872) resonances are considered as composite states containing both molecular hadronic and charmonium components. Having a leading molecular component in the X(3872) and a sole molecular configuration for the Y(4260) results in a prediction compatible with present data.

  8. Use of PCR for Detecting Aspergillus flavus in Maize Treated by Gamma Radiation Process

    Microsoft Academic Search

    Simone Aquino; Ralf Greiner; Ursula Konietzny; Regina H. Hassegawa; Tatiana Alves dos Reis; Benedito Corrêa; Anna Lucia C. H. Villavicencio

    2008-01-01

    The aim of this study was to verify the effects of gamma radiation process on the fungal DNA and the application of PCR in the detection of Aspergillus flavus in irradiated maize grains. The samples were inoculated with a toxigenic strain and incubated under controlled conditions of relative humidity, water activity, and temperature for 15 days. After incubation, the samples

  9. Short-lived variations in the background gamma-radiation dose.

    PubMed

    Burnett, J L; Croudace, I W; Warwick, P E

    2010-09-01

    Sudden increases in the background gamma-radiation dose may occur due to the removal of (222)Rn and (220)Rn progeny from the atmosphere by wet deposition mechanisms. This contribution has been measured using a Geiger-Muller detector at the Atomic Weapons Establishment (Aldermaston, UK) during July 2005-April 2006. The results are approximated by a log-normal distribution and there were nine separate occurrences of the gamma-radiation dose exceeding 125% of the geometric mean value. The increases were associated with periods of heavy rainfall, although no correlation was evident between the dose rate and the amount of rainfall, as increased rainfall dilutes the activity further rather than increasing its atmospheric removal. The events were preceded by periods of fine weather and atmospheric stability that allow for the build-up of (222)Rn and (220)Rn progeny. Similar increases in gamma-radiation dose have been measured at a nearby monitoring station situated approximately 11 miles from Aldermaston. Increases in gamma-radiation dose during heavy rainfall have also been observed throughout the UK, that followed the trajectory of an air mass. All events decreased to typical values within 1-2 h as the water permeated into the ground below and the radioactivity decayed away. PMID:20826890

  10. Luffa fibers and gamma radiation as improvement tools of polymer Gonzalo Martnez-Barrera a,

    E-print Network

    North Texas, University of

    [3,4]. The mix design of polymer concrete involves an aggregate size gradation to provide the lowestLuffa fibers and gamma radiation as improvement tools of polymer concrete Gonzalo Martínez-5017, USA h i g h l i g h t s Polymer concrete with silicious sand, unsaturated polyester resin and luffa

  11. Radiation-induced epilation due to couch transit dose for the Leksell Gamma Knife model C

    Microsoft Academic Search

    Carla D Bradford; Brian Morabito; Douglas R Shearer; Georg Norén; Prakash Chougule

    2002-01-01

    Purpose: To determine the cause of epilation at the top of the head for 2 patients with acoustic neuromas after undergoing fractionated radiosurgery with the Leskell Gamma Knife model C. This epilation was unexpected, because the treatment planning program stated the dose at this location was <0.1 Gy.Methods and Materials: The radiation dose along a central axis, parallel to the

  12. Inactivation of foodborne pathogens on crawfish tail meat using cryogenic freezing and gamma radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foodborne illness outbreaks occasionally occur as a result of microbiologically contaminated crustaceans, including crawfish. Cryogenic freezing and gamma radiation are two technologies which can be used to improve the microbiological safety and shelf-life of foods. In the U.S. the majority of non-c...

  13. Effect of hyperthermia on the radiation response of the mouse jejunum. [Whole-body. gamma. irradiation

    Microsoft Academic Search

    O. R. Merino; L. J. Peters; K. A. Mason; H. R. Withers

    1978-01-01

    The experiments reported show that the effect of radiation on the gut mucosa may be significantly enhanced by moderate hyperthermia (41 to 44°C) that is applied for 30 min before or after irradiation. The predominant effect of combined heat and radiation was to displace the radiation survival curves of jejunal crypt stem cells to the left without a significant change

  14. Radiation induced genomic instability in bystander cells

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Gu, S.; Randers-Pehrson, G.; Hei, T.

    There is considerable evidence that exposure to ionizing radiation may induce a heritable genomic instability that leads to a persisting increased frequency of genetic and functional changes in the non-irradiated progeny of a wide variety of irradiated cells Genomic instability is measured as delayed expressions in chromosomal alterations micronucleus formation gene mutations and decreased plating efficiency During the last decade numerous studies have shown that radiation could induce bystander effect in non-irradiated neighboring cells similar endpoints have also been used in genomic instability studies Both genomic instability and the bystander effect are phenomena that result in a paradigm shift in our understanding of radiation biology In the past it seemed reasonable to assume that the production of single- and double-strand DNA breaks are due to direct energy deposition of energy by a charged particle to the nucleus It turns out that biology is not quite that simple Using the Columbia University charged particle microbeam and the highly sensitive human hamster hybrid AL cell mutagenic assay we irradiated 10 of the cells with a lethal dose of 30 alpha particles through the nucleus After overnight incubation the remaining viable bystander cells were replated in dishes for colony formation Clonal isolates were expanded and cultured for 6 consecutive weeks to assess plating efficiency and mutation frequency Preliminary results indicated that there was no significant decrease in plating efficiency among the bystander colonies when compared with

  15. Presentation of IFN-gamma to nitric oxide-producing cells: a novel function for mast cells.

    PubMed

    Brooks, B; Briggs, D M; Eastmond, N C; Fernig, D G; Coleman, J W

    2000-01-15

    We report that mast cells can bind and present IFN-gamma in a functionally active form to macrophages. Flow-cytometric analysis revealed that biotinylated IFN-gamma bound equally well to purified peritoneal mast cells from both IFN-gammaR knockout and wild-type mice, indicating a non-IFN-gammaR binding site. Purified peritoneal mast cells, loaded with IFN-gamma for 30 min and washed, were able to induce NO synthesis by peritoneal macrophages. This response required cell contact and expression of IFN-gammaR on the responding macrophages, but not the mast cells. Human HMC-1 mast cells were also able to present IFN-gamma to mouse macrophages. Enzyme treatment of mouse mast cells revealed that binding of IFN-gamma was predominantly to chondroitin sulfate B (dermatan sulfate). Binding of IFN-gamma to dermatan sulfate was confirmed by inhibition ELISA. This study demonstrates for the first time that mast cells can present IFN-gamma to other cells via glycosaminoglycans. Mast cells may act as a reservoir of surface-stored functionally active cytokines. PMID:10623797

  16. Efficient modeling of compton diode gamma radiation detectors

    SciTech Connect

    Drumm, C.R.; Hohlfelder, J.J.; Kotulski, J.D.; Scrivner, G.L.; Mills, G.S.; Tanaka, T.J. (Sandia National Labs., Albuquerque, NM (United States))

    1992-08-01

    This paper reports on the CEPXS/ONELD code package which proves to be significantly more efficient than electron Monte Carlo for computing spherical Compton diode response to gamma irradiation, requiring only minutes instead of hours of Cray computer time. The adjoint capability of CEPXS/ONELD allows the complete energy-angle response of a Compton diode to be determined with a single transport calculation. The method is a useful tool for determining new Compton-diode designs with desired energy-response characteristics.

  17. M-BAND Study of Radiation-Induced Chromosome Aberrations in Human Epithelial Cells: Radiation Quality and Dose Rate Effects

    NASA Technical Reports Server (NTRS)

    Hada, Megumi; Cucinotta, Francis; Wu, Honglu

    2009-01-01

    The advantage of the multicolor banding in situ hybridization (mBAND) technique is its ability to identify both inter- (translocation to unpainted chromosomes) and intra- (inversions and deletions within a single painted chromosome) chromosome aberrations simultaneously. To study the detailed rearrangement of low- and high-LET radiation induced chromosome aberrations in human epithelial cells (CH184B5F5/M10) in vitro, we performed a series of experiments with Cs-137 gamma rays of both low and high dose rates, neutrons of low dose rate and 600 MeV/u Fe ions of high dose rate, with chromosome 3 painted with multi-binding colors. We also compared the chromosome aberrations in both 2- and 3-dimensional cell cultures. Results of these experiments revealed the highest chromosome aberration frequencies after low dose rate neutron exposures. However, detailed analysis of the radiation induced inversions revealed that all three radiation types induced a low incidence of simple inversions. Most of the inversions in gamma-ray irradiated samples were accompanied by other types of intra-chromosomal aberrations but few inversions were accompanied by inter-chromosomal aberrations. In contrast, neutrons and Fe ions induced a significant fraction of inversions that involved complex rearrangements of both inter- and intrachromosomal exchanges. The location of the breaks involved in chromosome exchanges was analyzed along the painted chromosome. The breakpoint distribution was found to be randomly localized on chromosome 3 after neutron or Fe ion exposure, whereas non-random distribution with clustering breakpoints was observed after -ray exposure. Our comparison of chromosome aberration yields between 2- and 3-dimensional cell cultures indicated a significant difference for gamma exposures, but not for Fe ion exposures. These experimental results indicated that the track structure of the radiation and the cellular/chromosome structure can both affect radiation-induced chromosome aberrations.

  18. Gallium arsenide solar cell radiation damage study

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Herbert, G. A.; Kinnison, J. D.; Meulenberg, A.

    1989-01-01

    A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the cell and its currents relatively more, while protons damage the junction of the cell and its voltages more. It is suggested that multiple defects due to protons in a strong field region such as a p/n junction cause the greater degradation in cell voltage, whereas the individual point defects in the quasi-neutral minority-carrier-diffusion regions due to electrons cause the greater degradation in cell current and spectral response.

  19. Radiation hardened high efficiency silicon space solar cell

    Microsoft Academic Search

    V. Garboushian; S. Yoon; J. Turner

    1993-01-01

    A silicon solar cell with AMO 19% Beginning of Life (BOL) efficiency is reported. The cell has demonstrated equal or better radiation resistance when compared to conventional silicon space solar cells. Conventional silicon space solar cell performance is generally ≈14% at BOL. The Radiation Hardened High Efficiency Silicon (RHHES) cell is thinned for high specific power (watts\\/kilogram). The RHHES space

  20. CARBON FIBRE COMPOSITE MATERIALS PRODUCED BY GAMMA RADIATION INDUCED CURING OF EPOXY RESINS

    SciTech Connect

    Dispenza, C.; Spadaro, G.; Alessi, S. [Dipartimento di Ingegneria Chimica dei Processi e dei Materiali (DICPM), Centro Interdipartimentale sui Materiali Compositi (CIRMAC), Universita di Palermo, Viale delle Scienze 90128, Palermo (Italy)

    2008-08-28

    It is well known that ionizing radiation can initiate polymerization of suitable monomers for many applications. In this work an epoxy difunctional monomer has been used as matrix of a carbon fibre composite in order to produce materials through gamma radiation, for aerospace and advanced automotive applications. Radiation curing has been performed at different absorbed doses and, as comparison, also thermal curing of the same monomer formulations has been done. Furthermore some irradiated samples have been also subjected to a post irradiation thermal curing in order to complete the polymerization reactions. The properties of the cured materials have been studied by moisture absorption isotherms, dynamic mechanical thermal analysis and mechanical flexural tests.

  1. Modification of silicone sealant to improve gamma radiation resistance, by addition of protective agents

    NASA Astrophysics Data System (ADS)

    González-Pérez, Giovanni; Burillo, Guillermina

    2013-09-01

    Poly (dimethylsiloxane) (PDMS) sealant (SS) was modified with the addition of different protective compounds to conserve its physical-chemical properties during gamma irradiation. 2-Vinyl naphthalene (2-VN), bisphenol-A (BPA) and poly (vinyl carbazole) (PVK) were used to evaluate radiation protection through the crosslinking effect of radiation. The samples were irradiated with doses from 100 kGy to 500 kGy at room temperature in air, with a 60Co gamma source, and the changes in molecular weight, thermal behavior, elastic properties and infrared spectra (FTIR-ATR) absorbance analysis were determined. The molecular weight of unmodified silicone sealant increases with the absorbed dose because of crosslinking as predominant effect. However, the crosslinking effect was inhibited with the addition of protective agent due to the aromatic compounds present. Modified silicone sealant films present better radiation resistance than unmodified system.

  2. Evaluation of phenolic compounds in maté ( Ilex paraguariensis) processed by gamma radiation

    NASA Astrophysics Data System (ADS)

    Furgeri, C.; Nunes, T. C. F.; Fanaro, G. B.; Souza, M. F. F.; Bastos, D. H. M.; Villavicencio, A. L. C. H.

    2009-07-01

    The radiation food processing has been demonstrating great effectiveness in the attack of pathogenic agents, while little compromising nutritional value and sensorial properties of foods. The maté ( Ilex paraguariensis), widely consumed product in South America, generally in the form of infusions with hot or cold water, calls of chimarrão or tererê, it is cited in literature as one of the best sources phenolic compounds. The antioxidants action of these constituent has been related to the protection of the organism against the free radicals, generated in alive, currently responsible for the sprouting of some degenerative illness as cancer, arteriosclerosis, rheumatic arthritis and cardiovascular clutters among others. The objective of that work was to evaluate the action of the processing for gamma radiation in phenolic compounds of tererê beverage in the doses of 0, 3, 5, 7 and 10 kGy. The observed results do not demonstrate significant alterations in phenolic compounds of tererê beverage processed by gamma radiation.

  3. Recent results on the effect of gamma radiation on the durability and microstructure of DWPF glass

    SciTech Connect

    Bibler, N.E.; Tosten, M.H.; Beam, D.C.

    1989-12-31

    The effect of gamma radiation on the durability and microstructure of a simulated nuclear waste glass from the Savannah River Site has been carefully investigated. Three large pieces of glass were irradiated with a Co-60 source to three doses up to a maximum dose of 3.1 {times} 10{sup 10} rad. Internal samples of the large pieces of irradiated and unirradiated glass were leached in deionized water to investigate durability changes and were examined by transmission electron microscopy (TEM) to investigate microstructure changes. Leach tests were performed in triplicate at 90{degree}C with crushed glass samples in deionized water. A statistical analysis of the results indicated to the 95% confidence level that the radiation did not affect the glass durability. Careful examination by TEM indicated no effect of gamma radiation on the microstructure of the glass although severe damage could be induced by the electron beam from the microscope. 19 refs., 2 figs., 3 tabs.

  4. Detection of DNA Damage by Space Radiation in Human Fibroblast Cells Flown on the International Space Station

    NASA Technical Reports Server (NTRS)

    Wu, Honglu; Lu, Tao; Wong, Michael; Beno, Jonathan; Countryman, Stefanie; Stodieck, Louis; Karouia, Fathi; Zhang, Ye

    2015-01-01

    Although charged particles in space have been detected with radiation detectors on board spacecraft since the early discovery of the Van Allen Belt, reports on effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation has been difficult due to the low dose and low dose rate nature of the radiation environment, and the difficulty in separating the radiation effects from microgravity and other space environmental factors. In astronauts, only a small number of changes, such as increased chromosome aberrations in lymphocytes and early onset of cataracts, attributed primarily to the exposure to space radiation. In a recent experiment, human fibroblast cells were flown on the International Space Station (ISS). Cells fixed on Days 3 and 14 after reaching orbit were analyzed for phosphorylation of a histone protein H2AX by immunofluorescent staining of cells, which is a widely used marker for DNA double strand breaks. The 3-dimensional gamma-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed a small fraction of foci that were larger and displayed a track pattern in the flight samples in comparison to the ground control. Human fibroblast cells were also exposed to low dose rate gamma rays, as well as to protons and Fe ions. Comparison of the pattern and distribution of the foci after gamma ray and charged particle exposure to our flight results confirmed that the foci found in the flown cells were indeed induced by space radiation.

  5. Glutamine protects Chinese Hamster Ovary cells from radiation killing

    Microsoft Academic Search

    Roger Winters; Richard Matthews; Nuran Ercal; Kalpana Krishnan

    1994-01-01

    Chinese Hamster Ovary (CHO) cells were propagated in vitro and exposed to varying doses of ionizing radiation. The surviving fraction of cells was determined, being found to be a function of the radiation dose. The cell survival curves obtained as a function of radiation dose were modified by the inclusion of varying doses of glutamine in the medium, with glutamine

  6. Favorable effect of gamma-radiation for in-stent restenosis: effect of diabetes on angiographic and clinical outcomes.

    PubMed

    Iakovou, Ioannis; Mehran, Roxana; Dangas, George; Lansky, Alexandra J; Stone, Gregg W; Mintz, Gary S; Aymong, Eve; Ashby, Dale T; Pichard, Augusto D; Satler, Lowell F; Kent, Kenneth; Leon, Martin B; Waksman, Ron

    2004-07-01

    The purpose of this study was to examine the effect of vascular brachytherapy with gamma-radiation (gamma-RT) in patients with diabetes mellitus (DM) with coronary in-stent restenosis (ISR). In the Washington Radiation for In-Stent Restenosis (WRIST) trial, 130 patients with ISR were treated with (192)Ir or placebo. Of the patients enrolled, 44 (34%) had DM (18 of them treated with gamma-RT and 26 with placebo). Gamma-radiation therapy of ISR in diabetics resulted in similar procedural success and in-hospital outcome compared to nondiabetics. At 6-month follow-up, both DM and non-DM patients treated with gamma-RT had significantly lower target lesion revascularization (TLR), target vessel revascularization, and major adverse cardiac event rates compared to placebo. DM remains a powerful predictor of TLR and major adverse cardiac events even after treatment of ISR with gamma-RT. PMID:15224295

  7. Distinct Cellular Calcium Metabolism in Radiation-sensitive RKO Human Colorectal Cancer Cells

    PubMed Central

    Kim, Yun Tai; Jo, Soo Shin; Park, Young Jun; Lee, Myung Za

    2014-01-01

    Radiation therapy for variety of human solid tumors utilizes mechanism of cell death after DNA damage caused by radiation. In response to DNA damage, cytochrome c was released from mitochondria by activation of pro-apoptotic Bcl-2 family proteins, and then elicits massive Ca2+ release from the ER that lead to cell death. It was also suggested that irradiation may cause the deregulation of Ca2+ homeostasis and trigger programmed cell death and regulate death specific enzymes. Thus, in this study, we investigated how cellular Ca2+ metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (?)-irradiation. In irradiated RKO cells, Ca2+ influx via activation of NCX reverse mode was enhanced and a decline of [Ca2+]i via forward mode was accelerated. The amount of Ca2+ released from the ER in RKO cells by the activation of IP3 receptor was also enhanced by irradiation. An increase in [Ca2+]i via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed. These results suggest that ?-irradiation elicits enhancement of cellular Ca2+ metabolism in radiation-sensitive RKO cells yielding programmed cell death. PMID:25598666

  8. Crosslinking of polyol(allylcarbonates) by gamma radiation

    NASA Astrophysics Data System (ADS)

    Delia López, V.; Esparza, Rosalío; Burillo, Guillermina

    1995-04-01

    Polyolallylcarbonate networks were synthesized in a vacuum at room temperature, with gamma irradiation, in a quiescent radical crosslinking polymerization. The polyfunctional monomers studied here were: diallylcarbonate (DAC), monoethylene glycol bis-allylcarbonate (MEGBAC), propylene glycol bis-allylcarbonate (PGBAC), dipropylene glycol bis-allylcarbonate (DPGBAC) and tris-allylcarbonate of glycerol (TACG). The results of the sol-gel analysis of irradiated monomers and characterization by IR, elemental analysis and GPC of different extracted fractions were that polyol(allylcarbonate of crosslinking via their ?-bonds (allylic group). The gelation doses are a function of the monomer reactivities, and of the monomer's chemical composition. TACG was the most reactive, while DAC crosslinked at the highest irradiation doses.

  9. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    SciTech Connect

    Not Available

    1989-01-01

    There are four areas where major progress has occurred this year. We have applied the Fourier-transform method of describing and analyzing Moessbauer effect (ME) line shapes to make measurements of the temperature dependence of the recoilless fraction in tungsten. We have carried out quasi-elastic measurements of the gamma scattering from viscous liquids, learning about diffusive motion in polydimethylsiloxane, pentadecane, and glycerol. We have made major progress in fundamental physics, having shown for the first time how to determine precise quantum interference parameters, obtaining experimental results on the 46.5 keV line of {sup 183}W and the 129 keV line of {sup 191}Ir. Finally, we have continued our development of MICE detectors, with a theoretical analysis of the MICE lineshape and its relation to the lineshape of conventional transmission ME spectroscopy. 12 refs.

  10. Predictions of induced background radiations at gamma/X-ray experiment envelopes in NASA spacecraft

    NASA Technical Reports Server (NTRS)

    Fischbein, W. L.; Debiak, T.; Rossi, M.; Stauber, M.; Suh, P.

    1979-01-01

    This work seeks to predict secondary radiation levels induced in spacecraft structures by space protons. The radiations analyzed are secondary neutrons from spallation and evaporation reactions and gamma and beta rays from the decay of induced radioactivity, as sources of interfering background to spaceborne measurements of galactic and planetary gamma rays below 10 MeV. The spacecraft considered are the Multi-Mission Spacecraft (MMS) and the Space Shuttle, modeled as spherical shells. The proton environment is that of the South Atlantic Anomaly, as well as cosmic ray protons. The induced radioactivity is analyzed in terms of its interference with various gamma-ray lines of astrophysical interest, as well as its contribution to several spectral regions of the gamma-ray continuum. The buildup of the line and continuum radioactivity background is predicted for a period of nearly 9 months in orbit (approximately 4100 orbits). In addition, background contributions from cosmic ray electron bremsstrahlung and earth gamma-ray albedo are estimated.

  11. Modern Methods of Real-Time Gamma Radiation Monitoring for General Personal Protection

    NASA Astrophysics Data System (ADS)

    Korostynska, O.; Arshak, K.; Arshak, A.; Vaseashta, Ashok

    Real-time radiation detectors become an essential part of emergency personnel who may have to respond to unknown accidents, incidents or terrorist attacks, which could involve radioactive material. More and more ordinary citizens are interested in personal radiation protection as well. Reasons include lost sources, nuclear industrial accidents, nuclear or radiological terrorism and the possibility of nuclear weapons being used in a war. People want to have the ability to measure it for themselves and they want to be notified when the radiation levels are increased. To meet this demand, considerable research into new sensors is underway, including efforts to enhance the sensor performance through both the material properties and manufacturing technologies. Deep understanding of physical properties of the materials under the influence of radiation exposure is vital for the effective design of dosimeter devices. Detection of radiation is based on the fact that both the electrical and the optical properties of the materials undergo changes upon the exposure to ionizing radiation. It is believed that radiation causes structural defects. The influence of radiation depends on both the dose and the parameters of the films including their thickness: the degradation is more severe for the higher dose and the thinner films. This paper presents overview of modern methods of real-time gamma radiation monitoring for personal protection of radiation workers and general public and suggests further developments in this area.

  12. Evaluation of fungal burden and aflatoxin presence in packed medicinal plants treated by gamma radiation.

    PubMed

    Aquino, Simone; Gonçalez, Edlayne; Rossi, Maria Helena; Nogueira, Juliana Hellmeister de Campos; Reis, Tatiana Alves Dos; Corrêa, Benedito

    2010-05-01

    This study was developed to evaluate the fungal burden, toxigenic molds, and mycotoxin contamination and to verify the effects of gamma radiation in four kinds of medicinal plants stored before and after 30 days of irradiation treatment. Eighty samples of medicinal plants (Peumus boldus, Camellia sinensis, Maytenus ilicifolia, and Cassia angustifolia) purchased from drugstores, wholesale, and open-air markets in São Paulo city, Brazil, were analyzed. The samples were treated using a (60)Co gamma ray source (Gammacell) with doses of 5 and 10 kGy. Nonirradiated samples were used as controls of fungal isolates. For enumeration of fungi on medicinal plants, serial dilutions of the samples were plated in duplicate onto dichloran 18% glycerol agar. The control samples revealed a high burden of molds, including toxigenic fungi. The process of gamma radiation was effective in reducing the number of CFU per gram in all irradiated samples of medicinal plants after 30 days of storage, using a dose of 10 kGy and maintaining samples in a protective package. No aflatoxins were detected. Gamma radiation treatment can be used as an effective method for preventing fungal deterioration of medicinal plants subject to long-term storage. PMID:20501045

  13. Effects of gamma radiation on codling moth, Cydia pomonella (L.), eggs

    NASA Astrophysics Data System (ADS)

    Mansour, M.; Mohamad, F.

    2004-12-01

    The radiosensitivity of codling moth, Cydia pomonella (L.), eggs in different stages of development was studied. Eggs ranging in age from 1-24 to 97-120 h were exposed, at 24 h intervals, to gamma radiation doses ranging from 10 to 350 Gy. The effects of gamma radiation on egg hatch, pupation and adult emergence was examined. Results showed that the radiosensitivity of codling moth eggs decreased with increasing age. Egg hatch in 1-24 h old eggs was significantly affected at 20 Gy dose and at 60 Gy dose, egg hatch decreased to about 1%. At the age of 25-48 h, however, egg hatch at 60 Gy dose was about 10%, and egg sensitivity to gamma irradiation decreased significantly in the 49-72 h age group; 60 Gy dose had no significant effect on egg hatch. Eggs irradiated few hours before hatch (at the blackhead stage), were the most resistant ones; 100 Gy had no significant effect on egg hatch and at 350 Gy dose over 56% of the eggs hatched. When adult emergence was used as a criterion for measuring effectiveness, however, the effect of gamma radiation was very sever. A dose of 60 Gy completely prevented adult emergence and at 100 Gy dose all resulted larvae died before pupation.

  14. 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.

  15. Interferon gamma decreases hepatic stellate cell activation and extracellular matrix deposition in rat liver fibrosis

    Microsoft Academic Search

    GS Baroni; L D'Ambrosio; P Curto; A Casini; R Mancini; AM Jezequel; A Benedetti

    1996-01-01

    Interferon gamma (IFN-gamma) inhibits in vitro the activation of hepatic stellate cells (HSC), the primary extracellular matrix-producing cells in liver fibrosis. This study was undertaken to determine in vivo the effect of IFN-gamma in the rat model of liver fibrosis induced by dimethylnitrosamine (DMN), where HSC activation represents an early response to cell injury. Rats were killed after 1 or

  16. Gamma\\/delta T cells and human skin reactivity to heavy metals

    Microsoft Academic Search

    K. Nordlind; S. Lidén

    1995-01-01

    Gamma\\/delta T cells may act as a first line of defence and respond to stress signals from the surrounding tissue. In the present investigation the occurrence of gamma\\/delta T cells was studied in the human skin after application of heavy metal salts by a routine epicutaneous patch-testing procedure. Gamma\\/delta cells were not found in normal skin. They were observed in

  17. Polymer Composites for Radiation Detection: Di-iodobenzene and light emitting polymer molecular solutions for gamma detection

    SciTech Connect

    Qibing Pei; Yongsheng Zhao; Haizheng Zhong [University of California, Los Angeles, California (United States)

    2008-07-01

    Conjugated polymers are largely intact by gamma exposure but can be energized in the presence of high-Z compounds. The resulting alteration of the polymer's high optical density and photoluminescence efficiency can be exploited for the detection of gamma radiation with high sensitivity. Di-iodobenzene and conjugated polymers mix on the molecular level in solid thin films. Composite films of various thicknesses were conveniently cast from solution and exposed to gamma radiation. The responses of the films to gamma dosage were observed with dramatic changes in ultraviolet-visible absorption and photoluminescence. (authors)

  18. Modulation of radiation-induced apoptosis and G{sub 2}/M block in murine T-lymphoma cells

    SciTech Connect

    Palayoor, S.T.; Macklis, R.M.; Bump, E.A.; Coleman, C.N. [Harvard Medical School, Boston, MA (United States)

    1995-03-01

    Radiation-induced apoptosis in lymphocyte-derived cell lines is characterized by endonucleolytic cleavage of cellular DNA within hours after radiation exposure. We have studied this phenomenon qualitatively (DNA gel electrophoresis) and quantitatively (diphenylamine reagent assay) in murine EL4 T-lymphoma cells exposed to {sup 137}Cs {gamma} irradiation. Fragmentation was discernible within 18-24 h after exposure. It increased with time and dose and reached a plateau after 8 Gy of {gamma} radiation. We studied the effect of several pharmacological agents on the radiation-induced G{sub 2}/M block and DNA fragmentation. The agents which reduced the radiation-induced G{sub 2}/M-phase arrest (caffeine, theobromine, theophylline and 2-aminopurine) enhanced the degree of DNA fragmentation at 24 h. In contrast, the agents which sustained the radiation-induced G{sub 2}/M-phase arrest (TPA, DBcAMP, IBMX and 3-aminobenzamide) inhibited the DNA fragmentation at 24 h. These studies on EL4 lymphoma cells are consistent with the hypothesis that cells with radiation-induced genetic damage are eliminated by apoptosis subsequent to a G{sub 2}/M block. Furthermore, it may be possible to modulate the process of radiation-induced apoptosis in lymphoma cells with pharmacological agents that modify the radiation-induced G{sub 2}/M block, and to use this effect in the treatment of patients with malignant disease. 59 refs., 7 figs.

  19. Investigation of solar cell radiation damage

    Microsoft Academic Search

    J. Bernard; R. Reulet; R. A. Arndt

    1974-01-01

    A facility for studying the influence of space radiations on the lifetime of solar arrays is described, in which the test samples are made to move past electron, proton, and photon sources. Measurement of such parameters as current-voltage characteristic, minority-carrier diffusion length, and window transmission, are carried out in vacuum immediately after irradiation. Results obtained for silicon cells and CdS

  20. Radiation-induced bystander effects in the Atlantic salmon (salmo salar L.) following mixed exposure to copper and aluminum combined with low-dose gamma radiation.

    PubMed

    Mothersill, Carmel; Smith, Richard W; Heier, Lene Sørlie; Teien, Hans-Christian; Lind, Ole Christian; Land, Ole Christian; Seymour, Colin B; Oughton, Deborah; Salbu, Brit

    2014-03-01

    Very little is known about the combined effects of low doses of heavy metals and radiation. However, such "multiple stressor" exposure is the reality in the environment. In the work reported in this paper, fish were exposed to cobalt 60 gamma irradiation with or without copper or aluminum in the water. Doses of radiation ranged from 4 to 75 mGy delivered over 48 or 6 h. Copper doses ranged from 10 to 80 ?g/L for the same time period. The aluminum dose was 250 ?g/L. Gills and skin were removed from the fish after exposure and explanted in tissue culture flasks for investigation of bystander effects of the exposures using a stress signal reporter assay, which has been demonstrated to be a sensitive indicator of homeostatic perturbations in cells. The results show complex synergistic interactions of radiation and copper. Gills on the whole produce more toxic bystander signals than skin, but the additivity scores show highly variable results which depend on dose and time of exposure. The impacts of low doses of copper and low doses of radiation are greater than additive, medium levels of copper alone have a similar level of effect of bystander signal toxicity to the low dose. The addition of radiation stress, however, produces clear protective effects in the reporters treated with skin-derived medium. Gill-derived medium from the same fish did not show protective effects. Radiation exposure in the presence of 80 ?g/L led to highly variable results, which due to animal variation were not significantly different from the effect of copper alone. The results are stressor type, stressor concentration and time dependent. Clearly co-exposure to radiation and heavy metals does not always lead to simple additive effects. PMID:24352529

  1. Foods for a Mission to Mars: Investigations of Low-Dose Gamma Radiation Effects

    NASA Technical Reports Server (NTRS)

    Gandolph, J.; Shand, A.; Stoklosa, A.; Ma, A.; Weiss, I.; Alexander, D.; Perchonok, M.; Mauer, L. J.

    2007-01-01

    Food must be safe, nutritious, and acceptable throughout a long duration mission to maintain the health, well-being, and productivity of the astronauts. In addition to a developing a stable pre-packaged food supply, research is required to better understand the ability to convert edible biomass into safe, nutritious, and acceptable food products in a closed system with many restrictions (mass, volume, power, crew time, etc.). An understanding of how storage conditions encountered in a long-term space mission, such as elevated radiation, will impact food quality is also needed. The focus of this project was to contribute to the development of the highest quality food system possible for the duration of a mission, considering shelf-stable extended shelf-life foods, bulk ingredients, and crops to be grown in space. The impacts of space-relevant radiation doses on food, bulk ingredient, and select candidate crop quality and antioxidant capacity were determined. Interestingly, increasing gamma-radiation doses (0 to 1000 Gy) did not always increase dose-related effects in foods. Intermediate radiation doses (10 to 800Gy) often had significantly larger impact on the stability of bulk ingredient oils than higher (1000Gy) radiation doses. Overall, most food, ingredient, and crop systems investigated showed no significant differences between control samples and those treated with 3 Gy of gamma radiation (the upper limit estimated for a mission to Mars). However, this does not mean that all foods will be stable for 3-5 years, nor does it mean that foods are stable to space radiation comprising more than gamma rays.

  2. High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation

    DOEpatents

    Chiles, Marion M. (Knoxville, TN); Mihalczo, John T. (Oak Ridge, TN); Blakeman, Edward D. (Oak Ridge, TN)

    1989-01-01

    A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

  3. Sensitometry of the response of a new radiochromic film dosimeter to gamma radiation and electron beams

    NASA Astrophysics Data System (ADS)

    McLaughlin, W. L.; Yun-Dong, Chen; Soares, C. G.; Miller, A.; Van Dyk, G.; Lewis, D. F.

    1991-04-01

    A new radiation-sensitive imaging material, called GafChromic™ Dosimetry Media, offers advances in high-dose radiation dosimetry and high-resolution radiography for gamma radiation and electrons. The potential uses in radiation processing, radiation sterilization of medical devices, population control of insects by irradiation, food irradiation, blood irradiation for organ-transplant immuno-suppression, clinical radiography, and industrial radiography have led to the present sensitometric study over the breadth of the wide dynamic range of this new routine detector and imaging material, namely, absorbed doses from 10 Gy to 5 × 10 4 Gy. The thin-coated film is colorless before irradiation, and registers a deep-blue image upon irradiation, with two absorption bands at about 650 nm (major band) and 600 nm (minor band). The response to electrons, in terms of increase in absorbance per unit absorbed dose, is the same as that to gamma radiation within the estimated uncertainty of the measurements (± 5%, 95% confidence level). The spatial resolving power is > 1200 lines/mm. After the first 24 hours, the image is stable over many months (within ± 5% in absorbance), however, the system should be irradiated and analyzed at approximately the temperatures used during calibration, because of temperature dependence during irradiation and readout, and temperatures greater than 55°C should be avoided.

  4. High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation

    DOEpatents

    Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.

    1987-02-27

    A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

  5. Activation of PPAR{gamma} is not involved in butyrate-induced epithelial cell differentiation

    SciTech Connect

    Ulrich, S. [1st Department of Medicine-ZAFES, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Waechtershaeuser, A. [1st Department of Medicine-ZAFES, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Loitsch, S. [1st Department of Medicine-ZAFES, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Knethen, A. von [1st Department of Biochemistry-ZAFES, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Bruene, B. [1st Department of Biochemistry-ZAFES, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Stein, J. [1st Department of Medicine-ZAFES, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany)]. E-mail: j.stein@em.uni-frankfurt.de

    2005-10-15

    Histone deacetylase-inhibitors affect growth and differentiation of intestinal epithelial cells by inducing expression of several transcription factors, e.g. Peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) or vitamin D receptor (VDR). While activation of VDR by butyrate mainly seems to be responsible for cellular differentiation, the activation of PPAR{gamma} in intestinal cells remains to be elucidated. The aim of this study was to determine the role of PPAR{gamma} in butyrate-induced cell growth inhibition and differentiation induction in Caco-2 cells. Treatment with PPAR{gamma} ligands ciglitazone and BADGE (bisphenol A diglycidyl) enhanced butyrate-induced cell growth inhibition in a dose- and time-dependent manner, whereas cell differentiation was unaffected after treatment with PPAR{gamma} ligands rosiglitazone and MCC-555. Experiments were further performed in dominant-negative PPAR{gamma} mutant cells leading to an increase in cell growth whereas butyrate-induced cell differentiation was again unaffected. The present study clearly demonstrated that PPAR{gamma} is involved in butyrate-induced inhibition of cell growth, but seems not to play an essential role in butyrate-induced cell differentiation.

  6. Gamma-melanocyte-stimulating hormone-like immunoreactivity in blood cells of human eosinophilic patients.

    PubMed

    Johansson, O; Virtanen, M; Hilliges, M; Hansson, L O

    1991-01-01

    The immunohistochemical localization of the peptide gamma-melanocyte-stimulating hormone (gamma-MSH) within human polymorphonuclear leucocytes of blood from eosinophilic patients is described. The gamma-MSH immunoreactivity was observed only in neutrophilic granulocytes leaving all other cell types immuno-negative. PMID:1805488

  7. Response of human HTB140 melanoma cells to conventional radiation and hadrons.

    PubMed

    Risti?-Fira, A; Todorovi?, D; Zakula, J; Keta, O; Cirrone, P; Cuttone, G; Petrovi?, I

    2011-01-01

    Conventional radiotherapy with X- and gamma-rays is one of the common and effective treatments of cancer. High energy hadrons, i.e., charged particles like protons and (12)C ions, due to their specific physics and radiobiological advantages are increasingly used. In this study, effectiveness of different radiation types is evaluated on the radio-resistant human HTB140 melanoma cells. The cells were irradiated with gamma-rays, the 62 MeV protons at the Bragg peak and in the middle of the spread-out Bragg peak (SOBP), as well as with the 62 MeV/u (12)C ions. The doses ranged from 2 to 24 Gy. Cell survival and proliferation were assessed 7 days after irradiation, whereas apoptosis was evaluated after 48 h. The acquired results confirmed the high radio-resistance of cells, showing better effectiveness of protons than gamma-rays. The best efficiency was obtained with (12)C ions due to higher linear energy transfer. All analyzed radiation qualities reduced cell proliferation. The highest proliferation was detected for (12)C ions because of their large killing capacity followed by small induction of reparable lesions. This enabled unharmed cells to preserve proliferative activity. Irradiations with protons and (12)C ions revealed similar moderate pro-apoptotic ability that is in agreement with the level of cellular radio-resistance. PMID:21777021

  8. Resistance of a cultured fish cell line (CAF-MM1) to. gamma. irradiation

    SciTech Connect

    Mitani, H.; Etoh, H.; Egami, N.

    1982-02-01

    Fish are generally more resistant to whole-body ionizing radiation than mammals. To study the radiosensitivity of fish in vitro, CAF-MM1 cells derived from the fin of the goldfish, Carassius auratus, were used. The survival parameters of CAF-MM1 obtained after ..gamma.. irradiation at 26/sup 0/C were 325 rad for D/sub o/, 975 rad for Dq, and 15 for n. No mammalian cell line with such a low sensitivity in the presence of O/sub 2/ has been reported. It was found that the large initial shoulder of the survival curve was paralleled by substantial repair of sublethal damage as evidenced by split-dose experiments. This low sensitivity to ..gamma.. irradiation did not change upon the administration of caffeine or postirradiation illumination, although these treatments were effective after uv irradiation. The decrease in the mitotic index in CAF-MM1 occurred immediately after irradiation, and it recovered within a very short time. This indicated that the duration of G2 arrest was shorter than that observed in mammalian cells. The data also suggest that the resistance of fish to whole-body irradiation is attributable to resistance at the cellular level.

  9. Variation of terrestrial gamma radiation in Toki, Japan—comparison between gamma-ray spectrometry using Ge semiconductor and ICP-MS measurement

    Microsoft Academic Search

    Y. Fujikawa; M. Fukui; T. Baba; T. Yoshimoto; E. Ikeda; M. Saito; H. Yamanishi; T. Uda

    2005-01-01

    The cause of the spatial variation in external radiation levels in the Toki area in Japan was investigated by in-situ measurements of gamma-ray spectrum and by collections and measurements of soil samples. It was found that the radionuclide contents of topsoil largely governed the radiation level while land exploitation, gardening activities, and concrete-building constructions caused the variation in radiation there.

  10. Space solar cells: High efficiency and radiation damage

    NASA Technical Reports Server (NTRS)

    Brandhorst, H., Jr.; Bernatowicz, D. T.

    1980-01-01

    The progress and status of efforts to increase the end-of-life efficiency of solar cells for space use is assessed. High efficiency silicon solar cells, silicon solar cell radiation damage, GaAs solar cell performance and radiation damage and 30 percent devices are discussed.

  11. Ionizing Radiation in Glioblastoma Initiating Cells

    PubMed Central

    Rivera, Maricruz; Sukhdeo, Kumar; Yu, Jennifer

    2013-01-01

    Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with a median survival of 12–15?months with treatment consisting of surgical resection followed by ionizing radiation (IR) and chemotherapy. Even aggressive treatment is often palliative due to near universal recurrence. Therapeutic resistance has been linked to a subpopulation of GBM cells with stem cell-like properties termed GBM initiating cells (GICs). Recent efforts have focused on elucidating resistance mechanisms activated in GICs in response to IR. Among these, GICs preferentially activate the DNA damage response (DDR) to result in a faster rate of double-strand break (DSB) repair induced by IR as compared to the bulk tumor cells. IR also activates NOTCH and the hepatic growth factor (HGF) receptor, c-MET, signaling cascades that play critical roles in promoting proliferation, invasion, and resistance to apoptosis. These pathways are preferentially activated in GICs and represent targets for pharmacologic intervention. While IR provides the benefit of improved survival, it paradoxically promotes selection of more malignant cellular phenotypes of GBM. As reviewed here, finding effective combinations of radiation and molecular inhibitors to target GICs and non-GICs is essential for the development of more effective therapies. PMID:23579692

  12. Effect of gamma radiation on the structural and optical properties of Polyethyleneterephthalate (PET) polymer

    NASA Astrophysics Data System (ADS)

    Siddhartha; Aarya, Suveda; Dev, Kapil; Raghuvanshi, Suresh Kumar; Krishna, J. B. M.; Wahab, M. A.

    2012-04-01

    Effect of 1.25 MeV gamma radiation on the structural and optical properties of virgin and gamma irradiated (0-2000 kGy) Polyethyleneterephthalate (PET) polymer samples are analyzed using powder X-ray diffractometer and UV-vis spectrophotometer. Diffraction pattern of PET polymer indicates the semi-crystalline in nature whereas the crystallinity increases with increasing dose of irradiation. The remarkable variation in crystallite size is also observed. The absorption and activation energy increase and the optical band gap (Eg) decreases with increasing dose in UV-vis studies. The existence of the maximum absorption, their shifting and broadening due to gamma irradiation in PET polymer are also discussed.

  13. Radiation damage in InP single crystals and solar cells

    SciTech Connect

    Yamaguchi, M.; Uemura, C.; Yamamoto, A.

    1984-03-15

    This paper shows that InP solar cell is more radiation resistant than Si and GaAs solar cells. /sup 60/Co ..gamma..-ray irradiation damage in InP solar cells was examined. Changes in minority carrier diffusion length and carrier concentration in irradiated InP single crystals were also investigated by electron beam induced current and capacitance-voltage methods for solar cells. A high carrier concentration p-InP substrate has lower concentration damage. Thus, an InP solar cell with a higher carrier concentration substrate has superior radiation resistance. Experimental results for radiation damage in InP solar cells were in satisfactory agreement with theoretical values, calculated from changes in minority carrier diffusion length and carrier concentration due to irradiation. Numerical analysis suggests that an InP solar cell with a higher carrier concentration substrate and a shallower junction should be relatively more radiation resistant. Annealing behavior for radiation damage in InP was also examined.

  14. High efficiency, radiation-hard solar cells

    SciTech Connect

    Ager III, J.W.; Walukiewicz, W.

    2004-10-22

    The direct gap of the In{sub 1-x}Ga{sub x}N alloy system extends continuously from InN (0.7 eV, in the near IR) to GaN (3.4 eV, in the mid-ultraviolet). This opens the intriguing possibility of using this single ternary alloy system in single or multi-junction (MJ) solar cells of the type used for space-based surveillance satellites. To evaluate the suitability of In{sub 1-x}Ga{sub x}N as a material for space applications, high quality thin films were grown with molecular beam epitaxy and extensive damage testing with electron, proton, and alpha particle radiation was performed. Using the room temperature photoluminescence intensity as a indirect measure of minority carrier lifetime, it is shown that In{sub 1-x}Ga{sub x}N retains its optoelectronic properties at radiation damage doses at least 2 orders of magnitude higher than the damage thresholds of the materials (GaAs and GaInP) currently used in high efficiency MJ cells. This indicates that the In{sub 1-x}Ga{sub x}N is well-suited for the future development of ultra radiation-hard optoelectronics. Critical issues affecting development of solar cells using this material system were addressed. The presence of an electron-rich surface layer in InN and In{sub 1-x}Ga{sub x}N (0 < x < 0.63) was investigated; it was shown that this is a less significant effect at large x. Evidence of p-type activity below the surface in Mg-doped InN was obtained; this is a significant step toward achieving photovoltaic action and, ultimately, a solar cell using this material.

  15. Public exposure due to external gamma background radiation in boundary areas of Iran.

    PubMed

    Pooya, S M Hosseini; Dashtipour, M R; Enferadi, A; Orouji, T

    2015-09-01

    A monitoring program in boundary areas of a country is an appropriate way to indicate the level of public exposure. In this research, gamma background radiation was measured using TL dosimeters at 12 boundary areas as well as in the capital city of Iran during the period 2010 to 2011. The measurements were carried out in semi-annual time intervals from January to June and July to December in each year. The maximum average dose equivalent value measured was approximately 70 ?Sv/month for Tehran city. Also, the average dose values obtained were less than 40 ?Sv/month for all the cities located at the sea level except that of high level natural radiation area of Ramsar, and more than 55 ?Sv/month for the higher elevation cities. The public exposure due to ambient gamma dose equivalent in Iran is within the levels reported by UNSCEAR. PMID:26057985

  16. Beta decay radiation signature from neutron-rich gamma-ray bursts?

    E-print Network

    Soebur Razzaque; Peter Meszaros

    2006-06-09

    Core collapse of massive stars and binary neutron stars or black hole-neutron star binary mergers are likely progenitors of long and short duration gamma-ray bursts respectively. Neutronized material in the former and neutron star material in the latter are ejected by the central engine implying a neutron-rich jet outflow. A free neutron, however, beta decays to a proton, an electron (beta) and an anti-neutrino in about fifteen minutes in its rest frame. Sudden creation of a relativistic electron is accompanied by radiation with unique temporal and spectral signature. We calculate here this radiation signature collectively emitted by all beta decay electrons from neutron-rich outflow. Detection of this signature may thus provide strong evidence for not only neutron but also for proton content in the relativistic gamma-ray burst jets.

  17. A New Natural Gamma Radiation Measurement System for Marine Sediment and Rock Analysis

    E-print Network

    Vasiliev, M A; Chubarian, G; Olsen, R; Bennight, C; Cobine, T; Fackler, D; Hastedt, M; Houpt, D; Mateo, Z; Vasilieva, Y B

    2010-01-01

    A new high-efficiency and low-background system for the measurement of natural gamma radioactivity in marine sediment and rock cores retrieved from beneath the seabed was designed, built, and installed on the JOIDES Resolution research vessel. The system includes eight large NaI(Tl) detectors that measure adjacent intervals of the core simultaneously, maximizing counting times and minimizing statistical error for the limited measurement times available during drilling expeditions. Effect to background ratio is maximized with passive lead shielding, including both ordinary and low-activity lead. Large-area plastic scintillator active shielding filters background associated with the high-energy part of cosmic radiation. The new system has at least an order of magnitude higher statistical reliability and significantly enhances data quality compared to other offshore natural gamma radiation (NGR) systems designed to measure geological core samples. Reliable correlations and interpretations of cored intervals are ...

  18. A new natural gamma radiation measurement system for marine sediment and rock analysis

    NASA Astrophysics Data System (ADS)

    Vasiliev, M. A.; Blum, P.; Chubarian, G.; Olsen, R.; Bennight, C.; Cobine, T.; Fackler, D.; Hastedt, M.; Houpt, D.; Mateo, Z.; Vasilieva, Y. B.

    2011-11-01

    A new high-efficiency and low-background system for the measurement of natural gamma radioactivity in marine sediment and rock cores retrieved from beneath the seabed was designed, built, and installed on the JOIDES Resolution research vessel. The system includes eight large NaI(Tl) detectors that measure adjacent intervals of the core simultaneously, maximizing counting times and minimizing statistical error for the limited measurement times available during drilling expeditions. Effect to background ratio is maximized with passive lead shielding, including both ordinary and low-activity lead. Large-area plastic scintillator active shielding filters background associated with the high-energy part of cosmic radiation. The new system has at least an order of magnitude higher statistical reliability and significantly enhances data quality compared to other offshore natural gamma radiation (NGR) systems designed to measure geological core samples. Reliable correlations and interpretations of cored intervals are possible at rates of a few counts per second.

  19. Effect of Gamma Radiation on the Ripening of Bartlett Pears 1

    PubMed Central

    Maxie, E. C.; Sommer, N. F.; Muller, Carlos J.; Rae, Henry L.

    1966-01-01

    Gamma radiation at doses of 300 Krad or more inhibits the ripening of Bartlett pears (Pyrus communis L.). Immediately after irradiation there is a transitory burst of C2H4, which subsequently declines in fruits subjected to inhibitory doses. Ethylene production associated with ripening begins at the same time in unirradiated fruits and those subjected to noninhibitory doses, but the latter produces much more C2H4 at the climacteric peak. Fruits subjected to inhibitory doses produce low levels of C2H4 unless subjected to exogenously applied C2H4, whereupon they produce enough of the gas to induce ripening in unirradiated fruits. Pears subjected to 300 and 400 Krad of gamma rays did not ripen even when held in a flowing atmosphere containing 1000 ppm of C2H4 for 8 days at 20°. It is concluded that the action of gamma rays on Bartlett pears involves both an inhibition of C2H4 production and a decreased sensitivity of the fruit to the ripening action of the gas. Ripening of Bartlett pears is inhibited by gamma radiation only when applied to preclimacteric fruit. PMID:16656274

  20. Operation of Bidirectional Switches (DIAC) and Silicon Controlled Rectifiers (SCR) in Gamma-Radiation Environment

    SciTech Connect

    Swidan, A.M.; El-Ghanam, S.M. [Women's College for Art, Science and Education, Ain- Shams University, Helioplis, Cairo (Egypt); Soliman, F.A.S. [Nuclear Materials Authority, P.O. Box 2404, Horrya-11361, Heliopolis, Cairo (Egypt)

    2005-03-17

    Gamma-irradiation effects on the electrical parameters of the Diode AC switch (DIAC; PHI37 500) and Silicon Controlled Rectifier (SCR; 2N4444) devices have been studied in detail, where gamma-dose up to 137 x 106 rad was found to cause a serious permanent damage on their electrical characteristics. A pronounced increase in the break-over voltage (from 31.5 to 35 V), holding-current (from 13 to 53 mA) and holding voltage (from 22 to 32 V) of the DIAC is noticed. Besides, a severe decrease in the dynamic break-over voltage range (from 10 to 2.5 V) and negative resistance (from -750 to -168 ohm) is also observed. Exposing the SCRs to gamma-radiation causes their turn-on voltage and forward voltage drop values to increase from 0.8 to 2.8 V and from 1.4 to 4.5 V, respectively. Additionally, the holding current increases to 18 mA although its initial value is 3.5 mA. For the two devices, the linear dependence and high sensitivity of their electrical parameters to gamma-dose suggest the application of such devices in the field of radiation dosimetry.

  1. Space solar cells - High efficiency and radiation damage

    Microsoft Academic Search

    H. W. Brandhorst Jr.; D. T. Bernatowicz

    1980-01-01

    The proceedings of the Third Solar Cell High Efficiency and Radiation Damage Meeting are outlined. The topics covered included high efficiency silicon solar cells, silicon solar cell radiation damage, GaAs solar cell performance, and 30 percent conversion devices. The study of radiation damage from a fundamental defect-centered basis is discussed and evaluated as a focus of future work. 18% AM0

  2. Method for detecting water equivalent of snow using secondary cosmic gamma radiation

    DOEpatents

    Condreva, K.J.

    1997-01-14

    Water equivalent of accumulated snow determination by measurement of secondary background cosmic radiation attenuation by the snowpack. By measuring the attenuation of 3-10 MeV secondary gamma radiation it is possible to determine the water equivalent of snowpack. The apparatus is designed to operate remotely to determine the water equivalent of snow in areas which are difficult or hazardous to access during winter, accumulate the data as a function of time and transmit, by means of an associated telemetry system, the accumulated data back to a central data collection point for analysis. The electronic circuitry is designed so that a battery pack can be used to supply power. 4 figs.

  3. Method for detecting water equivalent of snow using secondary cosmic gamma radiation

    DOEpatents

    Condreva, Kenneth J. (1420 Fifth St., Livermore, Alameda County, CA 94550)

    1997-01-01

    Water equivalent of accumulated snow determination by measurement of secondary background cosmic radiation attenuation by the snowpack. By measuring the attentuation of 3-10 MeV secondary gamma radiation it is possible to determine the water equivalent of snowpack. The apparatus is designed to operate remotely to determine the water equivalent of snow in areas which are difficult or hazardous to access during winter, accumulate the data as a function of time and transmit, by means of an associated telemetry system, the accumulated data back to a central data collection point for analysis. The electronic circuitry is designed so that a battery pack can be used to supply power.

  4. Studies in feed spoilage: prevention of spoilage in ground corn by gamma radiation 

    E-print Network

    Webb, Billy Dean

    1959-01-01

    mold respiration on whole wheat which had been exposed to doses of gamma radiation between 2, 5 6 x 10 and 3. 75 x 10 rep. ghent containing 12 and 20 percent moisture was irradiated and that which had been irradiated with 12 percent moisture... was adjusted to 20 percent moisture before respiration of the two samples was compared. There was no difference in the dose range (between 125, 000 and 625, 000 rep) required to eliminate mold respiration in wheat that was ir- radiated at the two moisture...

  5. Degradation of biochemical activity in soil sterilized by dry heat and gamma radiation

    NASA Technical Reports Server (NTRS)

    Shih, K. L.; Souza, K. A.

    1978-01-01

    The effect of soil sterilization by dry heat (0.08% relative humidity), gamma radiation, or both on soil phosphatase, urease, and decarboxylase activity was studied. Soil sterilized by a long exposure to dry heat at relatively low temperatures (eight weeks at 100.5 C) retained higher activities than did soil exposed to a higher temperature (two weeks at 124.5 C), while all activity was destroyed by four days at 148.5 C. Sterilization with 7.5 Mrads destroyed less activity than did heat sterilization. The effect of several individually nonsterizing doses of heat radiation is described.

  6. Breeding biology of tree swallows and house wrens in a gradient of gamma radiation

    Microsoft Academic Search

    R. Zach; K. R. Mayoh

    1982-01-01

    In a gradient of gamma radiation ranging from 38.7 mC.kg⁻¹.d⁻¹ to background levels of 0.05 ..mu..C.kg⁻¹.d⁻¹, Tree Swallows (Iridoprocne bicolor) and House Wrens (Troglodytes aedon) avoided nesting in areas of high radiation. Nest boxes selected by swallows and wrens had a mean exposure rate of only 9.3 and 6.6 ..mu..C.kg⁻¹.d⁻¹, respectively. Lateral and canopy vegetation indices and nest hole height

  7. Comparison of radiation damage in lead tungstate crystals under pion and gamma irradiation

    SciTech Connect

    Batarin, V.A.; Butler, J.; Davidenko, A.M.; Derevschikov, A.A.; Goncharenko, Y.M.; Grishin, V.N.; Kachanov, V.A.; Khodyrev, V.Y.; Konstantinov, A.S.; Kravtsov, V.I.; Kubota, Y.; Lukanin, V.S.; Matulenko, Y.A.; Melnick, Y.M.; Meschanin, A.P.; Mikhalin, N.E.; Minaev, N.G.; Mochalov, V.V.; Morozov, D.A.; Nogach, L.V.; Ryazantsev, A.V.; /Serpukhov,

    2003-12-01

    Studies of the radiation hardness of lead tungstate crystals produced by the Bogoroditsk Techno-Chemical Plant in Russia and the Shanghai Institute of Ceramics in China have been carried out at IHEP, Protvino. The crystals were irradiated by a 40 GeV pion beam. After full recovery, the same crystals were irradiated using a {sup 137}Cs {gamma}-ray source. The dose rate profiles along the crystal length were observed to be quite similar. We compare the effects of the two types of radiation on the crystals light output.

  8. Caffeine sensitization of cultured mammalian cells and human lymphocytes irradiated with gamma rays and fast neutrons: a study of relative biological effectiveness in relation to cellular repair

    SciTech Connect

    Hannan, M.A.; Gibson, D.P.

    1985-10-01

    The sensitizing effects of caffeine were studied in baby hamster kidney (BHK-21) cells and human lymphocytes following irradiation with gamma rays and fast neutrons. Caffeine sensitization occurred only when log-phase BHK cells and mitogen-stimulated lymphocytes were exposed to the two radiations. Noncycling (confluent) cells of BHK resulted in a shouldered survival curve following gamma irradiation while a biphasic curve was obtained with the log-phase cells. Survival in the case of lymphocytes was estimated by measurement of (TH)thymidine uptake. The relative biological effectiveness (RBE) of fast neutrons was found to be greater at survival levels corresponding to the resistant portions of the survival curves (shoulder or resistant tail). In both cell types, no reduction in RBE was observed when caffeine was present, because caffeine affected both gamma and neutron survival by the same proportion.

  9. Radiation hardness of plastic scintillating fiber against fast neutron and [gamma]-ray irradiation

    SciTech Connect

    Murakami, Akira; Yoshinaka, Hideki; Goto, Minehiko (Saga Univ. (Japan). Dept. of Physics)

    1993-08-01

    In future collider experiments, where a background radiation level is estimated to be very high, e.g. around 10[sup 2] [approximately] 10[sup 5] Gy/yr and 10[sup 11] [approximately] 10[sup 14] n/cm[sup 2]/yr at SSC, the detectors operating around the collision point in the experiments will encounter a considerable amount of radiation. Therefore, the detectors, especially the calorimeter, are required to be resistive against high radiation levels. From this point of view, it is of great importance to study the effects of radiation damage on the performance of the detectors. The authors report preliminary results of measurements of radiation hardness of the plastic scintillating fiber Kuraray SCSF-81 against irradiation with fast neutrons and [sup 60]Co [gamma]-rays in the region of the neutron fluence from 1 [times] 10[sup 11] to 5 [times] 10[sup 13] n/cm[sup 2] and the integrated [gamma]-ray dose from 890 to 10[sup 5] Gy, respectively. Deterioration of both intrinsic light yield and light transmittance of the SCSF-81 has been studied.

  10. Inactivation of human immunodeficiency virus by gamma radiation and its effect on plasma and coagulation factors

    SciTech Connect

    Hiemstra, H.; Tersmette, M.; Vos, A.H.; Over, J.; van Berkel, M.P.; de Bree, H. (Central Laboratory of The Netherlands, Red Cross Blood Transfusion Service, Amsterdam (Netherlands))

    1991-01-01

    The inactivation of HIV by gamma-radiation was studied in frozen and liquid plasma; a reduction of the virus titer of 5 to 6 logs was achieved at doses of 5 to 10 Mrad at -80 degrees C and 2.5 Mrad at 15 degrees C. The effect of irradiation on the biologic activity of a number of coagulation factors in plasma and in lyophilized concentrates of factor VIII (FVIII) and prothrombin complex was examined. A recovery of 85 percent of the biologic activity of therapeutic components present in frozen plasma and in lyophilized coagulation factor concentrates was reached at radiation doses as low as 1.5 and 0.5 Mrad, respectively. As derived from the first-order radiation inactivation curves, the radiosensitive target size of HIV was estimated to be 1 to 3 MDa; the target size of FVIII was estimated to be 130 to 160 kDa. Gamma radiation must be disregarded as a method for the sterilization of plasma and plasma-derived products, because of the low reduction of virus infectivity at radiation doses that still give acceptable recovery of biologic activity of plasma components.

  11. Durability and shielding performance of borated Ceramicrete coatings in beta and gamma radiation fields

    NASA Astrophysics Data System (ADS)

    Wagh, Arun S.; Sayenko, S. Yu.; Dovbnya, A. N.; Shkuropatenko, V. A.; Tarasov, R. V.; Rybka, A. V.; Zakharchenko, A. A.

    2015-07-01

    Ceramicrete™, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid-base reaction between magnesium oxide and mono potassium phosphate. Fillers are used to impart desired properties to the product. Ceramicrete's tailored compositions have resulted in several commercial structural products, including corrosion- and fire-protection coatings. Their borated version, called Borobond™, has been studied for its neutron shielding capabilities and is being used in structures built for storage of nuclear materials. This investigation assesses the durability and shielding performance of borated Ceramicrete coatings when exposed to gamma and beta radiations to predict the composition needed for optimal shielding performance in a realistic nuclear radiation field. Investigations were conducted using experimental data coupled with predictive Monte Carlo computer model. The results show that it is possible to produce products for simultaneous shielding of all three types of nuclear radiations, viz., neutrons, gamma-, and beta-rays. Additionally, because sprayable Ceramicrete coatings exhibit excellent corrosion- and fire-protection characteristics on steel, this research also establishes an opportunity to produce thick coatings to enhance the shielding performance of corrosion and fire protection coatings for use in high radiation environment in nuclear industry.

  12. [gamma]-radiation-induced changes in the chemical and physical structure of poly(ethylene terephthalate)

    Microsoft Academic Search

    Jin; Ho-Seon

    1992-01-01

    Poly(ethylene terephthalate) (PET) film was irradiated with [gamma]-rays in air at doses from 0 to 620 Mrad, and at the rate of 0l8 to 1.0 Mrad\\/hr. Radiation-induced physical structure changes were studied by DMA and DSC measurements. Tensile properties were measured to find interrelationships with chemical and physical structure changes. Below 100 Mrad, PET shows little change in NMR and

  13. Effect of gamma irradiation conditions on the radiation-induced degradation of isobutylene–isoprene rubber

    Microsoft Academic Search

    M. ?en; C. Uzun; Ö. Kantoglu; S. M. Erdo?an; V. Deniz; O. Güven

    2003-01-01

    The effect of gamma irradiation conditions on the radiation-induced degradation of uncrosslinked, commercial isobutylene–isoprene rubbers has been investigated in this study. Influence of dose rate and irradiation atmosphere on the degradation of butyl rubber has been followed by viscosimetric and chromatographic analyses. Limiting viscosity number of all butyl rubbers decreased sharply up to 100 kGy and leveled off at around

  14. Search for Bremsstrahlung radiation in quasi-free n p --> n p gamma reactions

    Microsoft Academic Search

    J. Przerwa; H.-H. Adam; A. Budzanowski; R. Czyzykiewicz; D. Grzonka; M. Janusz; L. Jarczyk; B. Kamys; A. Khoukaz; K. Kilian; P. Klaja; N. Lang; P. Moskal; W. Oelert; C. Piskor-Ignatowicz; T. Rozek; R. Santo; T. Sefzick; M. Siemaszko; J. Smyrski; A. Taeschner; P. Winter; M. Wolke; P. Wuestner; W. Zipper

    2004-01-01

    Due to the high sensitivity of the N N --> N N gamma reaction to the\\u000anucleon-nucleon potential, Bremsstrahlung radiation is used as a tool to\\u000ainvestigate details of the nucleon-nucleon interaction. Such investigations can\\u000abe performed at the cooler synchrotron COSY in the Research Centre Juelich, by\\u000adint of the COSY-11 detection system. The results of the identification of

  15. Gamma ray bursts may be blueshifted bundles of the relic radiation

    E-print Network

    Krasi?ski, Andrzej

    2015-01-01

    A hypothesis is proposed that the gamma-ray bursts (GRBs) may arise by blueshifting the emission radiation of hydrogen and helium generated during the last scattering epoch. The blueshift mechanism is provided by such a Lema\\^{\\i}tre -- Tolman (L--T) model, in which the bang-time function $t_B(r)$ is not everywhere constant. Blueshift arises on \\textit{radial} rays that are emitted over regions where $\\dril{t_B} r \

  16. Effects of Solvent on Gamma Radiation–Induced Graft Copolymerization of Acrylamide onto Poly (3-hydroxybutyrate)

    Microsoft Academic Search

    Maykel González-Torres; Arllene M. Perez-González; Manuel González-Perez; César Santiago-Tepantlán; Silvia G. Solís-Rosales; Aurelio H. Heredia-Jiménez

    2011-01-01

    In the present article the gamma radiation–induced graft copolymerization of acrylamide (AAm) onto poly (3-hydroxybutyrate) (PHB) has been carried out by the simultaneous irradiation method. The effect of different solvents on the graft reaction was investigated. The P(HB-g-AAm) thus synthesized were characterized by Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron micrography (SEM), swelling behavior,

  17. The Gamma Radiation from the Reaction D(p,?)3He

    Microsoft Academic Search

    G M Griffiths; J B Warren

    1955-01-01

    Using a scintillation counter for the measurement of the gamma radiation, the Q value of the reaction D(p,?)3He was found to be 5.50±0.03 MeV. The Doppler shift has been measured. The angular distribution was found to be nearly a pure sin2? pattern at all proton bombarding energies from 0.5 to 2 MeV but evidence has been obtained for a small

  18. Reconciling observed gamma-ray burst prompt spectra with synchrotron radiation?

    Microsoft Academic Search

    F. Daigne; Z. Bosnjak; G. Dubus

    2011-01-01

    Context. Gamma-ray burst emission in the prompt phase is often interpreted as synchrotron radiation from high-energy electrons accelerated in internal shocks. Fast synchrotron cooling of a power-law distribution of electrons leads to the prediction that the slope below the spectral peak has a photon index alpha = -3\\/2 (N(E) ? Ealpha). However, this differs significantly from the observed median value

  19. The recombination and tunnel current in GaAs-based solar cells: effect of radiation

    Microsoft Academic Search

    V. S. Kalinovsky; V. M. Andreev; V. V. Evstropov; V. P. Khvostikov; V. M. Lantratov

    2003-01-01

    The space charge (depletion) region of photovoltaic and tunnel p-n junctions, as appeared, give an essential contribution to the characteristics of multi-cascade solar cells and to their radiation tolerance. In the present work the mechanisms of current passage in GaAs p-n junctions and their evolution under irradiation with 6.78 MeV protons, 1 MeV electrons and gamma-rays from a Co\\/sup 60\\/

  20. Enhanced annealing of GaAs solar cell radiation damage

    Microsoft Academic Search

    R. Loo; R. C. Knechtli; G. S. Kamath

    1981-01-01

    Solar cells are degraded by radiation damage in space. Investigations have been conducted concerning possibilities for annealing this radiation damage in GaAs solar cells, taking into account the conditions favoring such annealing. It has been found that continuous annealing as well as the combination of injection annealing with thermal annealing can lead to recovery from radiation damage under particularly favorable

  1. A human esophageal epithelial cell model for study of radiation induced cancer and DNA repair

    NASA Astrophysics Data System (ADS)

    Huff, Janice; Patel, Zarana; Hada, Megumi; Cucinotta, Francis A.

    For cancer risk assessment in astronauts and for countermeasure development, it is essential to understand the molecular mechanisms of radiation carcinogenesis and how these mechanisms are influenced by exposure to the types of radiation found in space. We are developing an in vitro model system for the study of radiation-induced initiation and progression of esophageal carcinoma. Development of squamous cell carcinoma of the esophagus is associated with radiation exposure, as revealed by the significant enhanced in incidence rates for this type of cancer in the survivors of the atomic bomb detonations in Japan. It is also associated with poor nutritional status and micronutrient deficiencies, which are also important issues for long duration spaceflight. The possible synergies between nutritional issues and radiation exposure are unknown. Here we present the results of preliminary characterization of both normal and hTERT-immortalized esophageal epithelial cells grown in 2-dimensional culture. We analyzed DNA repair capacity by measuring the kinetics of formation and loss of gamma-H2AX foci following radiation exposure. Additionally, we analyzed induction of chromosomal aberrations using 3-color fluorescence in situ hybridization (FISH). Data were generated using both low LET (gamma rays) and high LET ions (1000 MeV/nucleon iron.

  2. Deinococcus radiotolerans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil.

    PubMed

    Cha, Seho; Srinivasan, Sathiyaraj; Seo, Taegun; Kim, Myung Kyum

    2014-01-01

    Two gamma-radiation-resistant bacterial strains, designated C1(T) and C2, were isolated from a soil sample collected at Jeongeup-Si, South Korea. These strains were observed to be Gram-negative, non-motile, rod-shaped, and to form pink colonies. Phylogenetic analysis based on 16S rRNA gene sequences revealed that these strains belong to the genus Deinococcus in the family Deinococcaceae. Strains C1(T) and C2 have the highest sequence similarities with Deinococcus daejeonensis MJ27(T) (97.56 %) and Deinococcus grandis DSM 39663(T) (97.50 %). Like other members of the genus Deinococcus, the novel isolates showed resistance to gamma-radiation with a D10 value in excess of 8 kGy. The isolates were found to have menaquinone MK-8 as the predominant respiratory quinone and an unidentified phosphoglycolipid as major polar lipid. In addition, the most abundant fatty acids of strain C1(T) were identified as C15:1 ?6c (25.5 %), C16:1 ?7c (18.7 %) and C15:0 (9.7 %). Genomic analysis results showed that the DNA G+C contents of strain C1(T) and C2 are 68.59 and 68.57 %, respectively. Taken together, the polyphasic taxonomic data support the proposal that the isolates C1(T) and C2 represent a novel species of the genus Deinococcus, for which the name Deinococcus radiotolerans sp. nov. is proposed. The type strain is a strain C1(T) (=KCTC 33150(T) = JCM 19173(T)). PMID:24190343

  3. Protection against radiation-induced oxidative stress in cultured human epithelial cells by treatment with antioxidant agents

    SciTech Connect

    Wan, X. Steven [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States); Ware, Jeffrey H. [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States); Zhou, Zhaozong [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States); Donahue, Jeremiah J. [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States); Guan, Jun [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States); Kennedy, Ann R. [Department of Radiation Oncology, University of Pennsylvania School of Medicine, Philadelphia, PA (United States)]. E-mail: akennedy@mail.med.upenn.edu

    2006-04-01

    Purpose: To evaluate the protective effects of antioxidant agents against space radiation-induced oxidative stress in cultured human epithelial cells. Methods and Materials: The effects of selected concentrations of N-acetylcysteine, ascorbic acid, sodium ascorbate, co-enzyme Q10, {alpha}-lipoic acid, L-selenomethionine, and vitamin E succinate on radiation-induced oxidative stress were evaluated in MCF10 human breast epithelial cells exposed to radiation with X-rays, {gamma}-rays, protons, or high mass, high atomic number, and high energy particles using a dichlorofluorescein assay. Results: The results demonstrated that these antioxidants are effective in protecting against radiation-induced oxidative stress and complete or nearly complete protection was achieved by treating the cells with a combination of these agents before and during the radiation exposure. Conclusion: The combination of antioxidants evaluated in this study is likely be a promising countermeasure for protection against space radiation-induced adverse biologic effects.

  4. Celestial diffuse gamma radiation above 30 MeV observed by SAS-2

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.; Hartman, R. C.

    1973-01-01

    The Small Astronomy Satellite (SAS)-2, launched on November 15, 1972, carried into orbit a 32-deck magnetic-core digitized spark chamber gamma ray telescope to study celestial gamma radiation in the energy range above 30 MeV. In the study of several regions with b sub 2 15 deg, a finite, diffuse flux of gamma rays with a steep energy spectrum in the energy region from 35 to 200 MeV is observed. Representing the energy spectrum by a power law of the form dJ/dE = AE to - alpha power over this energy range, alpha is found along with the integral flux above 100 MeV. Combining this result with existing low energy gamma ray data yields an energy spectrum which is not a simple power law in energy, as in the X-ray region, but which demonstrates first an increase and then a decrease in slope, consistent within uncertainties with that predicted by cosmological theories, including the continuous production of high energy gamma rays primarily from neutral pi mesons throughout the history of the universe.

  5. Branching Fractions and CP-Violating Asymmetries in Radiative B Decays to eta K gamma

    SciTech Connect

    Aubert, B.

    2008-05-14

    The authors present measurements of the CP-violation parameters S and C for the radiative decay B{sup 0} {yields} {eta}K{sub S}{sup 0}{gamma}; for B {yields} {eta}K{gamma} they also measure the branching fractions and for B{sup +} {yields} {eta}K{sup +}{gamma} the time-integrated charge asymmetry {Alpha}{sub ch}. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465 x 10{sup 6} B{bar B} pairs produced in e{sup +}e{sup -} annihilation. The results are S = -0.18{sub -0.46}{sup +0.49} {+-} 0.12, C = -0.32{sub -0.39}{sup +0.40} {+-} 0.07, {Beta}(B{sup 0} {yields} {eta}K{sup 0}{gamma}) = (7.1{sub -2.0}{sup +2.1} {+-} 0.4) x 10{sup -6}, {Beta}(B{sup +} {yields} {eta}K{sup +}{gamma}) = (7.7 {+-} 1.0 {+-} 0.4) x 10{sup -6}, and {Alpha}{sub ch} = (-9.0{sub -9.8}{sup +10.4} {+-} 1.4) x 10{sup -2}. The first error quoted is statistical and the second systematic.

  6. Enhancement of radiation cytotoxicity in murine cancer cells by electroporation: in vitro and in vivo studies.

    PubMed

    Shil, Pratip; Sanghvi, Surendra H; Vidyasagar, Pandit B; Mishra, Kaushala P

    2005-01-01

    Increasing evidence has accumulated in recent years to suggest that the cell membrane forms the vital common target for action by ionizing radiation and electroporation. The present work describes the use of electric pulses for enhancement of radiation-induced cytotoxicity of cancer cells both in vitro and in vivo. In vitro: low dose rate (0.37 Gy/min) Co60 gamma-rays (2 Gy) in combination with electric pulses of square wave (2 kV/cm, 200 micros duration, 8 pulses/burst, 10 times) significantly enhanced the cytotoxicity in Ehrlich ascites carcinoma cells (EAC), probably through enhanced production of intracellular reactive oxygen species (ROS). The intracellular generation of ROS and changes in oxidative damage-mediated membrane fluidity were determined by fluorescence using DCH-FDA and DPH, respectively, as probes. Both radiation and electroporation, separately, have been observed to produce ROS in a dose-dependent fashion. We show that the combined treatment of cells with radiation and electroporation significantly increased intracellular ROS and changed membrane fluidity of EAC cells as compared to the effects by each individual treatment. In vivo studies have been carried out with murine fibrosarcoma as a model system. The localized treatment of a fibrosarcoma tumor, grown in the right hind leg of Swiss mice, had been carried out using radiation (Co60 gamma-rays, 2 Gy, dose rate: 0.37 Gy/min) and electric pulses (1 kV/cm, 200 micros, 8 pulses/burst, 10 times). Studies on tumor growth kinetics have shown a significant growth delay (by 50% to that of control) 7 days after treatment of tumor with radiation and electroporation. The results suggest that radiocytotoxicity of tumor cells in vitro as well as in vivo were enhanced significantly by electric pulses, which may offer a potentially improved treatment of cancer. PMID:16393122

  7. Loss of p53 protein during radiation transformation of primary human mammary epithelial cells

    SciTech Connect

    Wazer, D.E.; Chu, Qiuming; Liu, Xiao Long; Gao, Qingshen; Safaii, H.; Band, V. (Tufts Univ. School of Medicine, Boston, MA (United States))

    1994-04-01

    The causative factors leading to breast cancer are largely unknown. Increased incidence of breast cancer following diagnostic or therapeutic radiation suggests that radiation may contribute to mammary oncogenesis. This report describes the in vitro neoplastic transformation of a normal human mammary epithelial cell strain, 76N, by fractionated [gamma]-irradiation at a clinically used dose (30 Gy). The transformed cells (76R-30) were immortal, had reduced growth factor requirements, and produced tumors in nude mice. Remarkably, the 76R-30 cells completely lacked the p53 tumor suppressor protein. Loss of p53 was due to deletion of the gene on one allele and a 26-bp deletion within the third intron on the second allele which resulted in abnormal splicing out of either the third or fourth exon from the mRNA. PCR with a mutation-specific primer showed that intron 3 mutation was present in irradiated cells before selection for immortal phenotype. 76R-30 cells did not exhibit G[sub 1] arrest in response to radiation, indicating a loss of p53-mediated function. Expression of the wild-type p53 gene in 76R-30 cells led to their growth inhibition. Thus, loss of p53 protein appears to have contributed to neoplastic transformation of these cells. This unique model should facilitate analyses of molecular mechanisms of radiation-induced breast cancer and allow identification of p53-regulated cellular genes in breast cells. 44 refs., 8 figs., 1 tab.

  8. Radiation inactivation of Paenibacillus larvae and sterilization of American Foul Brood (AFB) infected hives using Co60 gamma rays

    Microsoft Academic Search

    Zenaida M. De Guzman; Cleofas R. Cervancia; Kris Genelyn B. Dimasuay; Mitos M. Tolentino; Gina B. Abrera; Ma. Lucia C. Cobar; Alejandro C. Fajardo; Noel G. Sabino; Chitho P. Feliciano

    The effectiveness of gamma radiation in inactivating the Philippine isolate of Paenibacillus larvae was investigated. Spores of P. larvae were irradiated at incremental doses (0.1, 0.2, 0.4, 0.8 and 1.6kGy) of gamma radiation emitted by a 60Co source. Surviving spores were counted and used to estimate the decimal reduction (D10) value. A dose of 0.2kGy was sufficient to inactivate 90%

  9. Effect of 1. 33 Mev gamma radiation and 0. 5 Mev electrons on the mechanical properties of graphite fiber composites

    Microsoft Academic Search

    R. E. Fornes; J. D. Memory; N. Naranong

    1982-01-01

    Epoxy\\/graphite fiber, polyimide\\/graphite fiber, and polysulfone\\/graphite fiber composites were exposed to 1.33 Mev gamma irradiation and 0.5 Mev electron bombardment for varying periods of time. The effects of the irradiation treatments on the breaking stress and Young's modulus were studied by a three point bending test. Effects were small. Both electron radiation up to 5000 Mrad and gamma radiation up

  10. Neurotoxicity of human neural cells induced by space radiation: in vitro risk assessment and countermeasure

    NASA Astrophysics Data System (ADS)

    Guida, P.; Vazquez, M.; Kim, A.

    As the duration of space missions increases the potential for neurological damage to astronauts resulting from exposure to radiation also increases To explore the cytotoxic effects of low and high LET radiation on cells of the central nervous system we utilized a model in vitro system consisting of a human neuronal progenitor cell line NT2 and its terminally differentiated derivative hNT neurons We found that exposure to numerous forms of ionizing radiation induced cell detachment necrosis and apoptosis in time dose and LET dependent manners From the slopes of the dose-response curves we calculated RBE values for each form of heavy ion radiation A sequential field of 1 GeV n protons and iron ions induced apoptosis to a greater extent than either ion alone and the time between hits was also an important determining factor In addition cycling neuronal progenitor cells underwent a dramatic G2 phase specific cell cycle delay within 6 hours following exposure to either low or high LET radiation The molecular effects of HZE radiation were also investigated with an emphasis on the cell stress response protein p53 Heavy ion radiation induced expression of p53 in a time and dose dependent manner in both neuronal progenitor and mature neuronal cells Furthermore several post-translational modifications to the p53 protein were detected 2 hours after exposure to gamma rays Experiments incorporating pifithrin- alpha a small molecule inhibitor of p53 suggest that induction of both apoptosis and the cell cycle delay in human NT2 cells is

  11. Spectral measurements of direct and scattered gamma radiation at a boiling-water reactor site

    NASA Astrophysics Data System (ADS)

    Block, R. C.; Preiss, I. L.; Ryan, R. M.; Vargo, G. J.

    1990-12-01

    Quantitative surveys of direct and scattered gamma radiation emitted from the steam-power conversion systems of a boiling-water reactor and other on-site radiation sources were made using a directionally shielded HPGe gamma spectrometry system. The purpose of this study was to obtain data on the relative contributions and energy distributions of direct and scattered gamma radiation in the site environs. The principal radionuclide of concern in this study is 16N produced by the 16O(n,p) 16N reaction in the reactor coolant. Due to changes in facility operation resulting from the implementation of hydrogen water chemistry (HWC), the amount of 16N transported from the reactor to the main steam system under full power operation is excepted to increase by a factor of 1.2 to 5.0. This increase in the 16N source term in the nuclear steam must be considered in the design of new facilities to be constructed on site as well as the evaluation of existing facilities with repect to ALARA (As Low As Reasonably Achievable) dose limits in unrestricted areas. This study consisted of base-line measurements taken under normal BWR chemistry conditions in October, 1987 and a corresponding set taken under HWC conditions in July, 1988. Ground-level and elevated measurements, corresponding to second-story building height, were obtained. The primary conclusion of this study is that direct radiation from the steam-power conversion system is the predominant source of radiation in the site environs of this reactor and that air scattering (i.e. skyshine) does not appear to be significant.

  12. Production of interferon-gamma and tumour necrosis factor-alpha by human T-cell clones expressing different forms of the gamma delta receptor.

    PubMed Central

    Christmas, S E; Meager, A

    1990-01-01

    Panels of human T-cell clones bearing the gamma delta T-cell receptor (TcR) were obtained from peripheral blood and decidual tissue and maintained in the presence of interleukin-2 (IL-2). TcR V gamma and V delta gene expression was determined in 40 TcR delta 1+ clones using the gamma delta T-cell subset markers Ti gamma A and delta TCS1, in conjunction with Southern blot analysis using TcR J gamma and J delta probes. gamma delta T-cell clones, together with control alpha beta T-cell clones derived from the same lymphocyte populations, were stimulated with phytohaemagglutinin (PHA) and their ability to produce interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) tested using specific ELISA. Many clones representative of the major peripheral V gamma 9/V delta 2J1 subset produced high amounts of both cytokines and mean levels were not significantly different from those produced by alpha beta T-cell clones. Panels of clones expressing V gamma 9 and V delta 2J1 produced significantly higher levels of TNF-alpha than clones not expressing V delta 2J1 and those expressing V delta 1J1. There was no relationship between levels of IFN-gamma and TNF-alpha produced by individual gamma delta T-cell clones and also no relationship between their non-major histocompatibility complex (MHC)-restricted cytotoxic activity and levels of either cytokine. There was a significant tendency for gamma delta T-cell clones to produce more TNF-alpha than IFN-gamma in comparison to alpha beta T-cell clones. The significance of these findings is discussed in the light of the reported differences in distribution in vivo of V delta 1J1+ and V delta 2J1+ cells. Images Figure 1 PMID:2126252

  13. Characterization of ionizing radiation damage in DNA. Final report, February 1, 1977September 30, 1977. [Gamma radiation, fast neutrons, uv radiation

    Microsoft Academic Search

    1977-01-01

    An experimental method for the measurement of covalent DNA-protein cross-links in bacteriophage T7 based on phenol-water countercurrent distribution has been developed and a statistical model for quantitative interpretation of these measurements has been devised. It has been found that DNA-protein cross links accumulate linearly with dose in response to exposure to ⁶°Co gamma radiation at a rate .05 to .20

  14. Bystander responses in low dose irradiated cells treated with plasma from gamma irradiated blood

    NASA Astrophysics Data System (ADS)

    Acheva, A.; Georgieva, R.; Rupova, I.; Boteva, R.; Lyng, F.

    2008-02-01

    There are two specific low-dose radiation-induced responses that have been the focus of radiobiologists' interest in recent years. These are the bystander effect in non-irradiated cells and the adaptive response to a challenge dose after prior low dose irradiation. In the present study we have investigated if plasma from irradiated blood can act as a 'challenge dose' on low dose irradiated reporter epithelial cells (HaCaT cell line). The main aim was to evaluate the overall effect of low dose irradiation (0.05 Gy) of reporter cells and the influence of bystander factors in plasma from 0.5 Gy gamma irradiated blood on these cells. The effects were estimated by clonogenic survival of the reporter cells. We also investigated the involvement of reactive oxygen species (ROS) as potential factors involved in the bystander signaling. Calcium fluxes and mitochondrial membrane potential (MMP) depolarization were also examined as a marker for initiation of apoptosis in the reporter cells. The results show that there are large individual differences in the production of bystander effects and adaptive responses between different donors. These may be due to the specific composition of the donor plasma. The observed effects generally could be divided into two groups: adaptive responses and additive effects. ROS appeared to be involved in the responses of the low dose pretreated reporter cells. In all cases there was a significant decrease in MMP which may be an early event in the apoptotic process. Calcium signaling also appeared to be involved in triggering apoptosis in the low dose pretreated reporter cells. The heterogeneity of the bystander responses makes them difficult to be modulated for medical uses. Specific plasma characteristics that cause these large differences in the responses would need to be identified to make them useful for radiotherapy.

  15. Predominant activation and expansion of V gamma 9-bearing gamma delta T cells in vivo as well as in vitro in Salmonella infection.

    PubMed Central

    Hara, T; Mizuno, Y; Takaki, K; Takada, H; Akeda, H; Aoki, T; Nagata, M; Ueda, K; Matsuzaki, G; Yoshikai, Y

    1992-01-01

    Gamma delta T cell receptor-positive cells (gamma delta T cells) have recently been implicated to play a role in the protection against infectious pathogens. Serial studies on gamma delta T cells in 14 patients with salmonella infection have revealed that the proportions of gamma delta T cells (mean +/- SD: 17.9 +/- 13.2%) in salmonella infection were significantly increased (P less than 0.01) compared with 35 normal controls (5.0 +/- 2.6%) and 13 patients with other bacterial infections (4.0 +/- 1.4%). Expansion of gamma delta T cells was more prominent in the systemic form (28.9 +/- 10.8%) than in the gastroenteritis form (10.5 +/- 7.9%) of salmonella infection (P less than 0.01). Most in vivo-expanded gamma delta T cells expressed V gamma 9 gene product. Increased activated (HLA-DR+) T cells were observed in all the six patients with the systemic form and four of the seven with gastroenteritis form. Especially in the six with systemic form, gamma delta T cell activation was significantly higher than alpha beta T cell activation at the early stage of illness (P less than 0.01). When peripheral blood lymphocytes from normal individuals were cultured with live salmonella, gamma delta T cells were preferentially activated and expanded and most of them expressed V gamma 9. Purified gamma delta T cells also responded to live salmonella in vitro. The present study suggests that human gamma delta T cells play a role in the protection against salmonella infection in vivo. PMID:1386086

  16. Radiation inactivation of human prostate cancer cells: the role of apoptosis.

    PubMed

    Algan, O; Stobbe, C C; Helt, A M; Hanks, G E; Chapman, J D

    1996-09-01

    Radiation-induced apoptosis detected by gel electrophoresis was measured in cells of three human prostate carcinoma cell lines (TSU, PC-3 and DU-145) and compared to their intrinsic radiosensitivities as measured by clonogenic assays. The intrinsic radiosensitivities of each cell line were defined by their alpha and beta coefficients and their surviving fraction at 2 Gy, derived from complete survival curves. The temporal expression and kinetics of radiation-induced apoptosis for DU-145 cells, the human prostate carcinoma cell line which expressed the highest rate of radiation-induced apoptosis, was characterized further by differential sedimentation and the immunofluorescence assay (Apoptag) which was specific for 3'-OH ends in cellular DNA. Cell viability was measured microscopically with trypan blue staining. Cell survival after various doses was computer-fitted to either a simple linear or a linear-quadratic equation. Twenty-four hours after a 10-Gy dose of 137Cs gamma rays, DNA fragmentation to nucleosome multimers was strongly expressed in only DU-145 cells. In this cell line, when centrifugation at 12,000g for 10 min was used to separate fragmented from large molecular weight DNA, the proportion of DNA in the supernatant increased to a maximum of approximately 17% of the total by 10-12 h after radiation treatment. Cell death 24 h after irradiation measured by trypan blue exclusion assays followed single-hit kinetics up to 80 Gy. The proportion of cells which were labeled with Apoptag displayed single-hit kinetics and yielded the same inactivation coefficient as measured by trypan blue. Together, these data indicate that the rapid (24 h) inactivation of irradiated DU-145 cells results from apoptosis and accounts for about 5% of the single-hit killing measured by clonogenic assay. Temporal studies of radiation-induced killing of DU-145 cells distinguished this rapid mechanism of cell death from the major mechanism (72-144 h). These may correlate with apoptosis and proliferative cell death, respectively. Of the three prostate cancer cell lines investigated, only DU-145 cells displayed significant levels of radiation-induced DNA fragmentation and rapid cell death, with characteristics of apoptosis. This mechanism of cell death was complete by 24 h after irradiation and was well separated in time from the death of cells by the major mechanisms which occurred after 72 h, and accounted for about 5% of cell inactivation by a single-hit mechanism. PMID:8752304

  17. The ionization processes in the Fe XXVII region of hot iron plasma in the field of hard gamma radiation

    NASA Astrophysics Data System (ADS)

    Illarionov, A. F.

    1989-06-01

    A highly ionized hot plasma of an Fe-56-type heavy element in the field of hard ionizing gamma radiation is studied. Processes of ionization and recombination are discussed for a plasma consisting of fully ionized Fe XXVII and hydrogen-like Fe XXVI ions in the case of a large optical depth of the plasma with respect to photoionization by gamma-ray quanta. An equation of ionization balance is presented for a plasma in the Fe XXVII region formed around a powerful source of hard gamma-ray radiation.

  18. Gamma-H2AX as a biomarker of DNA damage induced by ionizing radiation in targeted and bystander human artificial skin models and peripheral blood lymphocytes

    NASA Astrophysics Data System (ADS)

    Redon, Christophe; Dickey, Jennifer; Bonner, William; Sedelnikova, Olga

    Ionizing radiation (IR) exposure is inevitable. In addition to exposure from cosmic rays, the sun and radioactive substances, modern society has created new sources of radiation exposure such as space and high altitude journeys, X-ray diagnostics, radiological treatments and the increasing threat of radiobiological terrorism. For these reasons, a reliable, reproducible and sensitive assessment of dose and time exposure to IR is essential. We developed a minimally invasive diagnostic test for IR exposure based on detection of a phosphorylated variant of histone H2AX (gamma-H2AX), which occurs specifically at sites of DNA double-strand breaks (DSBs). The phosphorylation of thousands of H2AX molecules forms a gamma-H2AX focus in the chromatin flanking the DSB site that can be detected in situ. We analyzed gamma- H2AX focus formation in both directly irradiated cells as well as in un-irradiated "bystanders" in close contact with irradiated cells. In order to insure minimal invasiveness, we examined commercially available artificial skin models as a surrogate for human skin biopsies as well as peripheral blood lymphocytes. In human skin models, cells in a thin plane were microbeamirradiated and gamma-H2AX formation was measured both in irradiated and in distal bystander cells over time. In irradiated cells DSB formation reached a maximum at 15-30 minutes post- IR and then declined within several hours; all cells were affected. In marked contrast, the incidence of DSBs in bystander cells reached a maximum by 12-48 hours post-irradiation, gradually decreasing over the 7 day time course. At the maxima, 40-60% of bystander cells were affected. Similarly, we analyzed blood samples exposed to IR ex vivo at doses ranging from 0.02 to 3 Gy. The amount of DNA damage was linear in respect to radiation dose and independent of the age or sex of the blood donor. The method is highly reproducible and highly sensitive. In directly irradiated cells, the number of gamma-H2AX foci peaked 30 min after irradiation and then declined at a relatively steady pace as the cell repaired the DNA damage. Radiation effects were still detectable after 48 hrs for doses greater than 1 Gy and remained linear to initial dose. Activated bystander lymphocytes cultured with media from irradiated lymphocytes exhibited a two-fold increased damage response as seen by gamma- H2AX formation. The effect reached a maximum 3 hrs post-exposure and was retained for over 24 hrs. Thus, detection of gamma-H2AX formation to determine DNA damage in a minimally invasive skin test and a non-invasive blood test could be useful and promising tools to analyze direct and indirect effects of radiation exposure.

  19. Low dose radiation induced senescence of human mesenchymal stromal cells and impaired the autophagy process.

    PubMed

    Alessio, Nicola; Del Gaudio, Stefania; Capasso, Stefania; Di Bernardo, Giovanni; Cappabianca, Salvatore; Cipollaro, Marilena; Peluso, Gianfranco; Galderisi, Umberto

    2015-04-10

    Low doses of radiation may have profound effects on cellular function. Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites.We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis.The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal. We also showed that low radiation affected the autophagic flux. We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence.An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells. This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination). PMID:25544750

  20. Low dose radiation induced senescence of human mesenchymal stromal cells and impaired the autophagy process

    PubMed Central

    Alessio, Nicola; Del Gaudio, Stefania; Capasso, Stefania; Di Bernardo, Giovanni; Cappabianca, Salvatore; Cipollaro, Marilena; Peluso, Gianfranco; Galderisi, Umberto

    2015-01-01

    Low doses of radiation may have profound effects on cellular function. Individuals may be exposed to low doses of radiation either intentionally for medical purposes or accidentally, such as those exposed to radiological terrorism or those who live near illegal radioactive waste dumpsites. We studied the effects of low dose radiation on human bone marrow mesenchymal stromal cells (MSC), which contain a subpopulation of stem cells able to differentiate in bone, cartilage, and fat; support hematopoiesis; and contribute to body's homeostasis. The main outcome of low radiation exposure, besides reduction of cell cycling, is the triggering of senescence, while the contribution to apoptosis is minimal. We also showed that low radiation affected the autophagic flux. We hypothesize that the autophagy prevented radiation deteriorative processes, and its decline contributed to senescence. An increase in ATM staining one and six hours post-irradiation and return to basal level at 48 hours, along with persistent gamma-H2AX staining, indicated that MSC properly activated the DNA repair signaling, though some damages remained unrepaired, mainly in non-cycling cells. This suggested that the impaired DNA repair capacity of irradiated MSC seemed mainly related to the reduced activity of a non-homologous end-joining (NHEJ) system rather than HR (homologous recombination). PMID:25544750

  1. 1989 neutron and gamma personnel dosimetry intercomparison study using RADCAL (Radiation Calibration Laboratory) sources

    SciTech Connect

    Sims, C.S.; Casson, W.H.; Patterson, G.R. (Oak Ridge National Lab., TN (USA)); Murakami, H. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Dept. of Health Physics); Liu, J.C. (Stanford Linear Accelerator Center, Menlo Park, CA (USA))

    1990-10-01

    The fourteenth Personnel Dosimetry Intercomparison Study (i.e., PDIS 14) was conducted during May 1-5, 1989. A total of 48 organizations (33 from the US and 15 from abroad) participated in PDIS 14. Participants submitted by mail a total of 1,302 neutron and gamma dosimeters for this mixed field study. The type of neutron dosimeter and the percentage of participants submitting that type are as follows: TLD-albedo (40%), direct interaction TLD (22%), track (20%), film (7%), combination (7%), and bubble detectors (4%). The type of gamma dosimeter and the percentage of participants submitting that type are as follows: TLD (84%) and film (16%). Radiation sources used in the six PDIS 14 exposures included {sup 252}Cf moderated by 15-cm D{sub 2}O, {sup 252}Cf moderated by 15-cm polyethylene (gamma-enhanced with {sup 137}Cs), and {sup 238}PuBe. Neutron dose equivalents ranged from 0.44--2.63 mSv and gamma doses ranged from 0. 01-1.85 mSv. One {sup 252}Cf(D{sub 2}O) exposure was performed at a 60{degree} angle of incidence (most performance tests are at perpendicular incidence). The average neutron dosimeter response for this exposure was 70% of that at normal incidence. The average gamma dosimeter response was 96% of that at normal incidence. A total of 70% of individual reported neutron dosimeter measurements were within {plus minus}50% of reference values. If the 0.01 mSv data are omitted, approximately 90% of the individual reported gamma measurements were within {plus minus}50% of reference values. 33 refs., 9 figs., 27 tabs.

  2. [gamma]-radiation-induced changes in the chemical and physical structure of poly(ethylene terephthalate)

    SciTech Connect

    Jin, Ho-Seon.

    1992-01-01

    Poly(ethylene terephthalate) (PET) film was irradiated with [gamma]-rays in air at doses from 0 to 620 Mrad, and at the rate of 0l8 to 1.0 Mrad/hr. Radiation-induced physical structure changes were studied by DMA and DSC measurements. Tensile properties were measured to find interrelationships with chemical and physical structure changes. Below 100 Mrad, PET shows little change in NMR and IR spectra. Fluorescence emission spectra, however, show the presence and increase of monohydroxy-substituted phenylene groups. This hydroxylation appears to stabilize the polymer. The phenylene group in PET also contributes to radiation-resistance. The amorphous-crystalline interfaces impede the penetration of oxygen and slow the oxidative chain scission. Between 100 and 215 Mrad, UV studies reveal that the rates of reaction begin to change rapidly. Chain scission appears to take place first in the interspherulitic amorphous regions and then in the intraspherulitic (interlamella) regions. [gamma]-Radiation-induced oxidative degradation shows aspects of both photolysis and of thermooxidative degradation (proton and carbon-13 NMR, and IR studies). It was concluded that the crystalline phase breaks down in to smaller crystallites, and these smaller crystallites grow in size by acting as nucleating sites. Tensile measurements show that throughout the range of irradiation studied the tensile strength at break and the percent elongation decrease. The tensile strength decreases uniformly and the percent elongation exhibits a more rapid decrease above 100 Mrad. The results of this study lead to the conclusion that [gamma]-radiation-induced oxidative degradation of PET involves products that are seen in both photolysis and thermooxidation.

  3. Age- and time interval-specific gamma radiation-induced DNA damage in adult maize weevils, Sitophilus zeamais Motschulsky, assessed using comet assays.

    PubMed

    Hasan, Md Mahbub; Todoriki, Setsuko; Miyanoshita, Akihiro; Imamura, Taro

    2012-01-24

    The gamma radiation-induced DNA damage in adult maize weevils, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), was assessed using single-cell electrophoresis (comet assay). Analysis of DNA damage following 0.5 and 1.0 kGy of gamma radiation was performed using cells from 1- and 15-day-old adults. Gamma-irradiated adults from both age groups showed typical DNA fragmentation, whereas cells from non-irradiated adults showed more intact DNA than young S. zeamais. Investigations using the comet assay showed that tail length, % tail DNA and % DNA damage all increased in adults of both age groups when compared to the control insects. A maximum comet length of 227.33 ?m was recorded for 15-day-old adults at 24h after irradiation with 1.0 kGy and a minimum of 50.12 ?m for 1-day-old adults at 0 h after irradiation with 0.5 kGy. The percentage of DNA damage increased up to 57.31% and 68.15% for 1- and 15-day-old adults, respectively, at 24h after irradiation with 1.0 kGy, whereas only 8.58% and 12.22% DNA damage were observed in the control batches. The results also showed that percentage of DNA damage increased at 24h after irradiation compared to that at 0 h. However, further studies are needed to confirm these results. PMID:22142832

  4. Radiation resistance of a gamma-ray irradiated nonlinear optic chromophore

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Taylor, Edward W.

    2009-11-01

    The radiation resistance of organic electro-optic and optoelectronic materials for space applications is receiving increased attention. An earlier investigation reported that guest-host poled polymer EO modulator devices composed of a phenyltetraene bridge-type chromophore in amorphous polycarbonate (CLD/APC) did not exhibit a decrease in EO response (i.e., an increase in modulation-switching voltage- V?) following irradiation by low dose [10-160 krad(Si)] 60Co gamma-rays. To provide further evidences to the observed radiation stability, the post-irradiation responses of 60Co gamma-rays on CLD1/APC thin films are examined by various chemical and spectroscopic methods including: a solubility test, thin-layer chromatography, proton nuclear magnetic resonance spectroscopy, UV-vis absorption, and infra-red absorption. The results indicate that CLD1 and APC did not decompose under gamma-ray irradiation at dose levels ranging from 66-274 krad(Si) and from 61-154 krad(Si), respectively which support the previously reported data.

  5. Effect of gamma radiation on growth and survival of common seed-borne fungi in India

    NASA Astrophysics Data System (ADS)

    Maity, J. P.; Chakraborty, A.; Chanda, S.; Santra, S. C.

    2008-07-01

    The present work describes radiation-induced effects of major seeds like Oryza sativa Cv-2233, Oryza sativa Cv-Shankar, Cicer arietinum Cv-local and seed-borne fungi like Alternaria sp., Aspergillus sp., Trichoderma sp. and Curvularia sp. 60Co gamma source at 25 °C emitting gamma ray at 1173 and 1332 keV energy was used for irradiation. Dose of gamma irradiation up to 3 kGy (0.12 kGy/h) was applied for exposing the seed and fungal spores. Significant depletion of the fungal population was noted with irradiation at 1-2 kGy, whereas germinating potential of the treated grain did not alter significantly. However, significant differential radiation response in delayed seed germination, colony formation of the fungal spores and their depletion of growth were noticed in a dose-dependent manner. The depletion of the fungal viability (germination) was noted within the irradiation dose range of 1-2 kGy for Alternaria sp. and Aspergillus sp., while 0.5-1 kGy for Trichoderma sp. and Curvularia sp. However, complete inhibition of all the selected fungi was observed above 2.5 kGy.

  6. Measurements of gamma radiation levels and spectra in the San Francisco Bay Area

    NASA Astrophysics Data System (ADS)

    Lo, B. T.; Brozek, K. P.; Angell, C. T.; Norman, E. B.

    2011-10-01

    Much of the radiation received by an average person is emitted by naturally-occurring radioactive isotopes from the thorium, actinium, and uranium decay series, or potassium. In this study, we have measured gamma radiation levels at various locations in the San Francisco Bay Area and the UC Berkeley campus from spectra taken using an ORTEC NOMAD portable data acquisition system and a large-volume coaxial HPGe detector. We have identified a large number of gamma rays originating from natural sources. The most noticeable isotopes are 214Bi, 40K, and 208Tl. We have observed variations in counting rates by factors of two to five between different locations due to differences in local conditions - such as building, concrete, grass, and soil compositions. In addition, in a number of outdoor locations, we have observed 604-, 662-, and 795-keV gamma rays from 134,137Cs, which we attribute to fallout from the recent Fukushima reactor accident. The implications of these results will be discussed. This work was supported in part by a grant from the U. S. Dept. of Homeland Security.

  7. Evaluation of The Combined Effects of Hyperthermia, Cobalt-60 Gamma Rays and IUdR on Cultured Glioblastoma Spheroid Cells and Dosimetry Using TLD-100

    PubMed Central

    Neshasteh-Riz, Ali; Rahdani, Rozhin; Mostaar, Ahmad

    2014-01-01

    Objective In radiation treatment, the irradiation which is effective enough to control the tumors far exceeds normal-tissues tolerance. Thus to avoid such unfavourable outcomes, some methods sensitizing the tumor cells to radiation are used. Iododeoxyuridine (IUdR) is a halogenated thymidine analogue that known to be effective as a radiosensitizer in human cancer therapy. Improving the potential efficacy of radiation therapy after combining to hyperthermia depends on the magnitude of the differential sensitization of the hyperthermic effects or on the differential cytotoxicity of the radiation effects on the tumor cells. In this study, we evaluated the combined effects of IUdR, hyperthermia and gamma rays of 60Co on human glioblastoma spheroids culture. Materials and Methods In this experimental study,the cultured spheroids with 100µm diameter were treated by 1 µM IUdR, 43°C hyperthermia for an hour and 2 Gy gamma rays, respectively. The DNA damages induced in cells were compared using alkaline comet assay method, and dosimetry was then performed by TLD-100. Comet scores were calculated as mean ± standard error of mean (SEM) using one-way ANOVA. Results Comparison of DNA damages induced by IUdR and hyperthermia + gamma treatment showed 2.67- and 1.92-fold enhancement, respectively, as compared to the damages induced by radiation alone or radiation combined IUdR. Dosimetry results showed the accurate dose delivered to cells. Conclusion Analysis of the comet tail moments of spheroids showed that the radiation treatments combined with hyperthermia and IUdR caused significant radiosensitization when compared to related results of irradiation alone or of irradiation with IUdR. These results suggest a potential clinical advantage of combining radiation with hyperthermia and indicate effectiveness of hyperthermia treatment in inducing cytotoxicity of tumor cells. PMID:24611138

  8. Interferon gamma and T cells inhibit osteogenesis induced by allogeneic mesenchymal stromal cells

    PubMed Central

    Dighe, Abhijit S.; Yang, Scott; Madhu, Vedavathi; Balian, Gary; Cui, Quanjun

    2012-01-01

    The mesenchymal stromal cells (MSCs) are reported to be immunoprivileged and osteogenic. We hypothesized that the use of allogeneic MSCs for bone repair was possible if they displayed an ability to induce similar osteogenesis in syngeneic as well as in allogeneic hosts. To test this hypothesis we used a cloned bone marrow derived cell, termed D1, isolated from Balb/c mice. The D1 cells were subcutaneously injected in syngeneic Balb/c, allogeneic immunocompetent B6, allogeneic T-cell deficient NCr nude and allogeneic B6 Pfp ?/? Rag2 ?/? mice that lacks matured T-cells and B-cells as well as NK cell cytolytic functions. D1 cells formed ectopic bones only in syngeneic or allogeneic immunocompromised hosts but not in allogeneic B6 hosts. The lack of T-cells alone in allogeneic NCr mice was sufficient to promote osteogenesis in allogeneic environment. We observed a significantly higher number of T-cells, B-cells, macrophages and significantly higher expression of interferon gamma (IFN-?) in B6 allogeneic implants as compared to the syngeneic implants. These factors correlated with severe inhibition of expression of alkaline phosphatase, osteocalcin and runx2 genes in the implants from B6 mice. Our data suggests that strategies to inhibit T-cells and IFN-? functions will be useful for bone repair mediated by allogeneic MSCs. PMID:22886855

  9. THE COMPARATIVE INVESTIGATION OF METHODS OF THE DETERMINATION OF SULFUR IN ORGANIC PRODUCTS USING ABSORPTION OF X AND GAMMA RADIATIONS

    Microsoft Academic Search

    L. Gorski; J. Grabczak

    1963-01-01

    The possibilities of applicntion of isotopic sources of gamma and x ; radiations for the determination of sulfur in hydrocarbons are discussed. The ; analytical methods are based on the absorption of radiation utilizing a ; difference between the absorption coefficients of hydrocarbon and sulfur for the ; energy about 20 kev. The properties of a Sn¹¹³ source whlch has

  10. Effect of Gamma Radiation on the Physiological Properties and Genetic Materials of Streptomyces albaduncus and S. erythogresius

    Microsoft Academic Search

    L. A. A. MOUSSA; F. A. MANSOUR; M. S. SERAG; S. A. M. ABOU

    Out of 14 isolates of actinomycetes, isolated from Egyptian soils, the two thermophilic isolates identified as Streptomyces albaduncus and S. erythogresius showed the highest antimicrobial activities against bacteria, moulds and yeasts among them. Both isolates were exposed to increasing doses of gamma radiation up to 5 kGy. All radiation doses used did not affect the physiological properties, but relativity higher

  11. Simple method to demonstrate radiation-inducible radiation resistance in microbial cells

    SciTech Connect

    Tan, S.T.; Maxcy, R.B.

    1986-01-01

    A simple method for detection of radiation-inducible radiation resistance was developed by irradiating aliquots (0.01 ml) of cell suspension on agar plates. Part of each experimental plate was subjected to an induction treatment, and subsequent radiation resistance was compared with that of untreated cells on the same plate. The UV radiation resistance of a Micrococcus sp. was increased approximately 1.6 times by an induction treatment. This simple procedure of irradiating cells in a fixed position on agar avoided washing, centrifugation, and cell enumeration required in traditional methods.

  12. Intestinal intraepithelial lymphocytes are a distinct set of gamma delta T cells.

    PubMed

    Bonneville, M; Janeway, C A; Ito, K; Haser, W; Ishida, I; Nakanishi, N; Tonegawa, S

    1988-12-01

    Lymphocytes are most reliably subdivided on the basis of their receptors for antigen at the cell surface. Three subtypes of lymphocytes are well defined: B cells that bear surface immunoglobulin and make antibody, CD4+T cells with CD3 alpha beta receptors specific for antigen associated with class II major histocompatibility complex molecules, and CD8+T cells with CD3 alpha beta receptors specific for antigen associated with class I MHC molecules. These T cells are responsible for known forms of cell-mediated immunity. The discovery of a third rearranging T-cell specific gene called gamma (refs 1 and 2) has revealed the presence of a new class of T cells bearing a new receptor type, CD3 gamma delta (refs 3-7). To date, neither the function nor the specificity of cells bearing this receptor has been determined. Because gamma delta T cells are the main lymphocyte of epidermis, it was proposed that such cells could be important in surveillance of all epithelia. We have isolated intraepithelial lymphocytes from murine small intestine, and shown that they predominantly or exclusively express CD3 gamma delta receptors. Unlike the epidermal lymphocytes, these cells also express CD8, and they use a different V lambda gene to form their receptor. This strongly suggests that gamma delta T cells home in a very specific manner to epithelia, where they presumably mediate their function. PMID:2461518

  13. Determination of the Dark Matter profile from the EGRET excess of diffuse Galactic gamma radiation

    E-print Network

    Markus Weber

    2007-10-26

    The excess above 1 GeV in the energy spectrum of the diffuse Galactic gamma radiation, measured with the EGRET experiment, can be interpreted as the annihilation of Dark Matter (DM) particles. The DM is distributed in a halo around the Milky Way. Considering the directionality of the gamma ray flux it is possible to determine the halo profile. The DM within the halo has a smooth and a clumpy component.These components can have different profiles as suggested by N-body simulations and the data is indeed compatible with a NFW profile for the diffuse component and a cored profile for the clumpy component.These DM clumps can be partly destroyed by tidal forces from interactions with stars and the gravitational potential of the Galactic disc.This effect mainly decreases the annihilation signal from the Galactic centre (GC). In this paper constraints on the different profiles and the survival probability of the clumps are discussed.

  14. Absorption of Very High Energy Gamma-Rays by Intergalactic Infrared Radiation: A New Determination

    E-print Network

    F. W. Stecker; O. C. De Jager

    1998-04-20

    We present a new calculation of the intergalactic gamma-ray absorption coefficient as a function of both energy and redshift. In reexamining this problem, we make use of a new, empirically based calculation (as opposed to previous model calculations) of the intergalactic infrared radiation field. We find smaller opacities than those given previously (Stecker & De Jager 1997). We apply our results to the new observations of the flaring gamma-ray spectra of Mrk421 and Mrk501, both at a redshift of apx. 0.03. Our new calculations indicate that there should be no significant curvature in the spectra of these sources for energies below 10 TeV, as indicated by recent observations. However, the intrinsic spectra of these sources should be harder by apx. 0.2 to 0.45 in the spectral index in the 1 to 10 TeV range with an intergalactic absorption cutoff above apx. 20 TeV.

  15. Antibacterial properties of Au doped polycarbonate synthesized by gamma radiation assisted diffusion method

    NASA Astrophysics Data System (ADS)

    Hareesh, K.; Deore, Avinash V.; Dahiwale, S. S.; Sanjeev, Ganesh; Kanjilal, D.; Ojha, Sunil; Dhole, N. A.; Kodam, K. M.; Bhoraskar, V. N.; Dhole, S. D.

    2015-07-01

    Gold (Au)-Polycarbonate (PC) matrix was prepared by gamma radiation assisted diffusion of Au nanoparticles in PC matrix. UV-Visible spectroscopy showed the surface plasmon resonance around 550 nm which corresponds to Au and this peak shift towards lower wavelength i.e. blue shift indicating the decrease in particle size of Au. Rutherford Backscattering (RBS) experiment confirmed the diffusion of Au in PC and depth of diffusion is found to be around 0.85 ?m. X-ray Diffractogram (XRD) results also revealed the diffusion of Au in PC where the peak observed at 2??38.29° which correspond to the FCC structure. Scanning Electron Microscope (SEM) images showed the hexagonal shaped Au nanoparticles and average particle size is found to be around 110 nm. These samples also showed anti-bacterial properties with both gram positive and gram negative bacteria's and revealed the inhibition of the overall growth of the bacteria with gamma dose.

  16. Radiative-neutron-capture gamma-ray analysis by a linear combination technique

    USGS Publications Warehouse

    Tanner, A.B.; Bhargava, R.C.; Senftle, F.E.; Brinkerhoff, J.M.

    1972-01-01

    The linear combination technique, when applied to a gamma-ray spectrum, gives a single number indicative of the extent to which the spectral lines of a sought element are present in a complex spectrum. Spectra are taken of the sought element and of various other substances whose spectra interfere with that of the sought element. A weighting function is then computed for application to spectra of unknown materials. The technique was used to determine calcium by radiative-neutron-capture gamma-ray analysis in the presence of interfering elements, notably titanium, and the results were compared with those for two popular methods of peak area integration. Although linearity of response was similar for the methods, the linear combination technique was much better at rejecting interferences. For analyses involving mixtures of unknown composition the technique consequently offers improved sensitivity. ?? 1972.

  17. Gamma-ray escape peak characteristics of radiation-damaged reverse-electrode germanium coaxial detectors

    NASA Astrophysics Data System (ADS)

    Pehl, Richard H.; Hull, Ethan L.; Madden, Norman W.; Xing, Jingshu; Friesel, Dennis L.

    1996-02-01

    A comparison of the characteristics of full-energy gamma-ray peaks and their corresponding escape peaks when high energy photons interact in radiation damaged reverse-electrode (n-type) germanium coaxial detectors is presented. Coaxial detector geometry is the dominant factor, causing charge collection to be dramatically better for interactions occurring near the outer periphery of the detector as well as increasing of the probability of escape events occurring in this region. It follows that the resolution of escape peaks is better than that of ordinary gamma-ray peaks. This is experimentally verified. A nearly identical but undamaged detector exhibited significant Doppler broadening of single escape peaks. Because double escape events preferentially occur at outer radii, energy shifts of double escape reflect extremely small amounts of charge trapping in undamaged detectors.

  18. Gamma-Ray Escape Peak Characteristics of Radiation Damaged Reverse-Electrode Germanium Detectors

    NASA Astrophysics Data System (ADS)

    Hull, E. L.; Xing, J. S.; Friesel, D. L.; Pehl, R. H.; Madden, N. M.

    1996-05-01

    A comparison between the characteristics of escape peaks and ordinary, multiple Compton and photoelectrically interacting, full-energy gamma-ray peaks from radiation damaged reverse-electrode (n-type) germanium coaxial detectors is presented. Coaxial detector geometry is the dominant factor, causing charge collection to be dramatically better near the outer periphery of the detector as well as increasing the probability of escape events occurring in this region. It follows that the resolution of escape peaks is better than that of ordinary gamma-ray peaks. This is experimentally verified. However, a nearly identical but undamaged detector exhibited significant Doppler broadening of single escape peaks. Because double escape events preferentially occur at outer radii, energy shifts in double escape peaks reflect extremely small amounts of charge trapping.

  19. Signature of gravitational radiation in afterglow of short Gamma-Ray Bursts?

    E-print Network

    Fan, Yi-Zhong; Wei, Da-Ming

    2013-01-01

    Short Gamma-Ray Bursts (GRBs) are brief intense emission of $\\gamma-$rays characterized by a duration shorter than 2 seconds and some, if not all of them, are likely powered by the coalescence of binary neutron stars. Sometimes the remnants may be supramassive highly-magnetized neutron stars (magnetars) with a typical rotational period $P_0 \\sim 1$ ms and the rapid rotation prevents the gravitational collapse until a good fraction of the rotational energy has been lost. Plausible observational evidence for the short-living magnetar central engine reported in the literature is the X-ray plateaus followed by an abrupt decline identified in some short GRB afterglow. We however find that with a moderate/high radiation efficiency favored by the very dim optical afterglow emission, the observed duration of some X-ray plateaus are significantly shorter than that expected in the dipole radiation model (i.e., the magnetar collapsed considerably earlier than the prediction of the pure dipole radiation). We suggest that...

  20. Effect of gamma radiation on chlorobutyl rubber vulcanized by three different crosslinking systems

    NASA Astrophysics Data System (ADS)

    Scagliusi, Sandra R.; Cardoso, Elisabeth L. C.; Lugao, Ademar B.

    2012-09-01

    The development of halogenated butyl rubber (chlorobutyl) in the 1950s and 1960s greatly extended the usefulness of butyl. Their properties allowed the development of more durable tubeless tires with the air retaining innerliner, chemically bonded to the body of the tire. Tire innerliners are by far the largest application for halobutyl. When polymers are subjected to high energy radiation, a number of chemical reactions may occur following the initial ionization and excitation events. These reactions lead to changes in the molecular weight of the polymer through scission (S) and crosslinking (X) of the molecules and affect the physical and mechanical properties. In the halobutyl rubbers the chain scission may predominate. This work aims to show effects of gamma radiation in properties of chlorobutyl rubbers vulcanized with sulfur, sulfur donor and phenolic resin. The butyl rubber has been already studied by us previously. The samples were characterized before and after irradiation. Gamma radiation doses used were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 kGy, in order to identify which cure system is the most stable under irradiation. In this study we observed that the properties of all samples were affected irrespective of the vulcanization system.

  1. Hepatocyte growth factor protects endothelial cells against gamma ray irradiation-induced damage

    Microsoft Academic Search

    Shun-ying Hu; Hai-feng Duan; Qing-fang Li; Yue-feng Yang; Jin-long Chen; Li-sheng Wang; Hua Wang

    2009-01-01

    Aim:To investigate the effect of HGF on proliferation, apoptosis and migratory ability of human vascular endothelial cells against gamma ray irradiation.Methods:ECV304 cells derived from adult human umbilical vein endothelial cells (HUVEC) were irradiated with a single gamma ray dose of 20 Gy. Immunocytochemistry and Western blot analysis were used to detect c-Met protein expression and HGF\\/c-Met signal pathway. In the

  2. Ionizing radiation-induced gene expression changes in TP53 proficient and deficient glioblastoma cell lines.

    PubMed

    Godoy, P R D V; Mello, S S; Magalhães, D A R; Donaires, F S; Nicolucci, P; Donadi, E A; Passos, G A; Sakamoto-Hojo, E T

    2013-08-30

    The genetic heterogeneity presented by different cell lines derived from glioblastoma (GBM) seems to influence their responses to antitumoral agents. Although GBM tumors present several genomic alterations, it has been assumed that TP53, frequently mutated in GBM, may to some extent be responsible for differences in cellular responses to antitumor agents, but this is not clear yet. To directly determine the impact of TP53 on GBM response to ionizing radiation, we compared the transcription profiles of four GBM cell lines (two with wild-type (WT) TP53 and two with mutant (MT) TP53) after 8Gy of gamma-rays. Transcript profiles of cells analyzed 30 min and 6h after irradiation showed that WT TP53 cells presented a higher number of modulated genes than MT TP53 cells. Our findings also indicate that there are several pathways (apoptosis, DNA repair/stress response, cytoskeleton organization and macromolecule metabolic process) in radiation responses of GBM cell lines that were modulated only in WT TP53 cells (30 min and 6h). Interestingly, the majority of differentially expressed genes did not present the TP53 binding site, suggesting secondary effects of TP53 on transcription. We conclude that radiation-induced changes in transcription profiles of irradiated GBM cell lines mainly depend on the functional status of TP53. PMID:23817105

  3. Development of human epithelial cell systems for radiation risk assessment

    NASA Technical Reports Server (NTRS)

    Yang, C. H.; Craise, L. M.

    1994-01-01

    The most important health effect of space radiation for astronauts is cancer induction. For radiation risk assessment, an understanding of carcinogenic effect of heavy ions in human cells is most essential. In our laboratory, we have successfully developed a human mammary epithelial cell system for studying the neoplastic transformation in vitro. Growth variants were obtained from heavy ion irradiated immortal mammary cell line. These cloned growth variants can grow in regular tissue culture media and maintain anchorage dependent growth and density inhibition property. Upon further irradiation with high-Linear Energy Transfer (LET) radiation, transformed foci were found. Experimental results from these studies suggest that multiexposure of radiation is required to induce neoplastic tranformation of human epithelial cells. This multihits requirement may be due to high genomic stability of human cells. These growth variants can be useful model systems for space flight experiments to determine the carcinogenic effect of space radiation in human epithelial cells.

  4. Analysis of Chromosomal Aberrations after Low and High Dose Rate Gamma Irradiation in ATM or NBS Suppressed Human Fibroblast Cells

    NASA Technical Reports Server (NTRS)

    Hada, M.; Huff, J. L.; Patel, Z.; Pluth, J. M.; George, K. A.; Cucinotta, F. A.

    2009-01-01

    A detailed understanding of the biological effects of heavy nuclei is needed for space radiation protection and for cancer therapy. High-LET radiation produces more complex DNA lesions that may be non-repairable or that may require additional processing steps compared to endogenous DSBs, increasing the possibility of misrepair. Interplay between radiation sensitivity, dose, and radiation quality has not been studied extensively. Previously we studied chromosome aberrations induced by low- and high- LET radiation in several cell lines deficient in ATM (ataxia telangactasia mutated; product of the gene that is mutated in ataxia telangiectasia patients) or NBS (nibrin; product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase (DNA-PK) activity. We found that the yields of both simple and complex chromosomal aberrations were significantly increased in the DSB repair defective cells compared to normal cells. The increased aberrations observed for the ATM and NBS defective lines was due to a significantly larger quadratic dose-response term compared to normal fibroblasts for both simple and complex aberrations, while the linear dose-response term was significantly higher in NBS cells only for simple exchanges. These results point to the importance of the functions of ATM and NBS in chromatin modifications that function to facilitate correct DSB repair and minimize aberration formation. To further understand the sensitivity differences that were observed in ATM and NBS deficient cells, in this study, chromosomal aberration analysis was performed in normal lung fibroblast cells treated with KU-55933, a specific ATM kinase inhibitor, or Mirin, an MRN complex inhibitor involved in activation of ATM. We are also testing siRNA knockdown of these proteins. Normal and ATM or NBS suppressed cells were irradiated with gamma-rays and chromosomes were collected with a premature chromosome condensation (PCC) technique at the first mitosis post-irradiation. Chromosomes were analyzed using a multicolor fluorescence in-situ hybridization (mFISH) chromosome painting method. Preliminary analysis showed that chromosomal exchanges were increased in the cells treated with the specific ATM inhibitor. Possible cytogenetic signatures of acute and low dose-rate gamma irradiation in ATM or Nibrin deficient and suppressed cells will be discussed.

  5. Study of radiation dose induced by cosmic-ray origin low-energy gamma rays and electrons near sea level

    NASA Astrophysics Data System (ADS)

    Mrdja, D.; Bikit, I.; Bikit, K.; Slivka, J.; Anicin, I.

    2015-02-01

    For a long time, it has been known that low-energy continuous gamma radiation is present in open air at the Earth's surface. In previous investigations it was assumed that this radiation is produced almost exclusively by gamma photons emitted due to the natural radioactivity, which are backscattered by air above ground. We show that significant amount of this radiation (related to energy region 30-300 keV) that peaks at about 90 keV, is produced by cosmic-rays, with the photon flux of about 3000 m-2 s-1. We find that the contribution of this omnipresent low-energy gamma radiation of cosmic-ray origin, including the corresponding low-energy electron flux, to the doses of general population are non-negligible components of overall doses induced by cosmic rays near sea level.

  6. Chromosomal Aberrations in DNA Repair Defective Cell Lines: Comparisons of Dose Rate and Radiation Quality

    NASA Technical Reports Server (NTRS)

    George, K. A.; Hada, M.; Patel, Z.; Huff, J.; Pluth, J. M.; Cucinotta, F. A.

    2009-01-01

    Chromosome aberration yields were assessed in DNA double-strand break repair (DSB) deficient cells after acute doses of gamma-rays or high-LET iron nuclei, or low dose-rate (0.018 Gy/hr) gamma-rays. We studied several cell lines including fibroblasts deficient in ATM (product of the gene that is mutated in ataxia telangiectasia patients) or NBS (product of the gene mutated in the Nijmegen breakage syndrome), and gliomablastoma cells that are proficient or lacking in DNA-dependent protein kinase, DNA-PK activity. Chromosomes were analyzed using the fluorescence in-situ hybridization (FISH) chromosome painting method in cells at the first division post-irradiation and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). Gamma radiation induced higher yields of both simple and complex exchanges in the DSB repair defective cells than in the normal cells. The quadratic dose-response terms for both chromosome exchange types were significantly higher for the ATM and NBS defective lines than for normal fibroblasts. However, the linear dose-response term was significantly higher only for simple exchanges in the NBS cells. Large increases in the quadratic dose response terms indicate the important roles of ATM and NBS in chromatin modifications that facilitate correct DSB repair and minimize aberration formation. Differences in the response of AT and NBS deficient cells at lower doses suggests important questions about the applicability of observations of radiation sensitivity at high dose to low dose exposures. For all iron nuclei irradiated cells, regression models preferred purely linear and quadratic dose responses for simple and complex exchanges, respectively. All the DNA repair defective cell lines had lower Relative biological effectiveness (RBE) values than normal cells, the lowest being for the DNA-PK-deficient cells, which was near unity. To further investigate the sensitivity differences for low and low high doses, we performed chronic low dose-rate irradiation, and have begun studies with ATM and Nibrin inhibitors and siRNA knockout of these proteins. Results support the conclusion that for the endpoint of simple chromosomal aberrations (translocation or dicentrics), the increased radiation sensitivity of AT cells found at high doses (>1 Gy) does not carry over to low doses or doserates, while NBS cells show increased sensitivity for both high and low dose exposures.

  7. Analysis of cytogenetic effects of the secondary radiation resulting from 70 GeV protons of chinese hamster cells

    NASA Astrophysics Data System (ADS)

    Akhmadieva, A. Kh.; Aptikaeva, G. Ph.; Livanova, I. A.; Antipov, A. V.; Akoev, I. G.; Ganassi, E. E.

    The cell culture of a Chinese hamster was irradiated on a Serpuchov proton synchrotron at a dose of 0.5-4 Gy and a dose rate of 1 Gy/min and by gamma-irradiation at dose 1-5 Gy and dose rate 1.2-1.4 Gy/min. The effect of radiation on the cell culture was judged from chromosomal aberrations in G2-stage of cell cycle and micronuclear test. The relative biological efficience of the secondary radiation was approximately 3. Modifying effect of caffeine on the cells irradiated by secondary radiation of synchrotron was not observed. In the presence of caffeine the effect of ?-irradiation practically is increased up to the level observed upon secondary irradiation. This suggests that secondary radiation inhibits the repair of the cytogenetic damage.

  8. Selective gene amplification in mammalian cells after exposure to 60Co gamma rays, 241Am alpha particles, or uv light

    SciTech Connect

    Luecke-Huhle, C.P.; Pech, M.; Herrlich, P.

    1986-06-01

    Simian Virus 40 wild type (SV40)-transformed Chinese hamster embryo cells (Co631) contain about five viral copies integrated per cell genome. These SV40 sequences were used as endogenous indicator genes to study the response of mammalian cells to radiation at the gene level. An increase in copy number was detected by dispersed cell blotting and Southern analysis in combination with specific DNA hybridization. All types of radiation tested induce a 15- to 25-fold amplification of SV40 sequences without producing intact virus. The amplification is dose dependent and increases with time after irradiation: a maximum effect is observed at Day 3 after alpha particle or uv exposure and at Day 6 after gamma-ray exposure. A RBE of 6 can be calculated for alpha particles if amplification rates at Day 3 are compared. However, when the maximum effect is considered independent of time, no difference between different types of radiation is observed. Southern blots of genomic DNA show that not all integrated SV40 sequences are amplified upon radiation. Amplified sequences are found either in restriction fragments of relatively high molecular weight or in unit size fragments. SV40 amplification is selective in that the amplification of other genes, e.g., of alpha-actin, dhfr (dihydrofolate reductase), and of two oncogenes of the ras family (Kirsten ras and Harvey ras), was below detection level.

  9. Morphological features of cloned lymphocytes expressing gamma/delta T cell receptors.

    PubMed

    Arancia, G; Malorni, W; Iosi, F; Zarcone, D; Cerruti, G; Favre, A; Zeromski, J; Grossi, C E; Moretta, A

    1991-01-01

    We have analyzed the morphological characteristics of human T lymphocytes bearing CD3-associated T cell receptor (TcR) gamma and delta chains. BB3 and delta-TCS1 monoclonal antibodies (mAb) were used to identify two distinct, nonoverlapping populations of TcR gamma/delta + cells which express the products of V delta 2 and V delta 1 gene segments, respectively. In the peripheral blood, most V delta 1+ (delta TCS-1+) lymphocytes express the non-disulfide-linked form of receptor whereas V delta 2+ (BB3+) cells express the disulfide-linked form. The majority of cloned TcR gamma/delta + cells exhibit a growth pattern different from that of conventional TcR alpha/beta + cells as they adhere promptly to surfaces and undergo morphological changes which can be summarized as follows: cells spread on the surface, form a distinct uropod and, in the final phase of adherence, emit long filopodia ending with adhesion plaques. Immunofluorescence studies of TcR gamma/delta + clones demonstrated the presence of submembraneous actin microfilaments and actin-binding protein confirming that these cells are capable of active motility which is related to the propensity of TcR gamma/delta + cells to home to epithelia. Scanning electron microscope analyses of effector/target cell conjugates showed that in TcR gamma/delta + cells the region of the uropodia next to the cell body is responsible for the binding to tumor target cells. Interestingly, immunofluorescence analyses revealed that LFA-1 molecules are predominantly distributed in the uropodium whereas they are virtually absent in the cell bodies. These morphological characteristics of TcR gamma/delta + cells may pertain to defensive mechanisms the mucosal level. PMID:1991486

  10. Modification of fecundity and fertility during oogenesis by. gamma. radiation and/or ozone with a cytological analysis in the ectoparasitic wasp, Habrobracon juglandis (Ashmead)

    SciTech Connect

    Ofuoku, E.E.

    1984-01-01

    In Experiment I, adult female wasps were exposed to ozone for 0, 2, 4, 6, 8, 10, 12, 16, 24, and 27 h. The results indicated that the 27 h of ozone exposure produced 100% lethality on the first day. Exposures below 27 h progressively decreased life span with increasing length of exposure. In Experiment II A, adult virgin Habrobracon females were exposed to ozone for 0, 2, 4, 6, 8, 10, 12, 16, and 24 h to determine the effects of ozone on fecundity (egg laying ability) and fertility (egg hatching ability). The results showed that ozone significantly decreased fecundity and fertility in all meiotic stages except metaphase I. In Experiment II B, adult virgin Habrobracon females were exposed to Co-60 ..gamma.. radiation. All treated wasps showed significant progressive decreases in fecundity and fertility with increases in radiation dose. In Experiment II C, adult virgin Habrobracon females were exposed to Co-60 ..gamma.. radiation, to ozone, or to combinations thereof to determine the effects of these insults on fecundity and fertility. Together or singly ozone and radiation reduced fecundity and fertility. In Experiment III, adult virgin Habrobracon females were exposed to the conditions of Experiment II C to correlate by cytological examination of the ovarioles the effects of ionizing radiation and/or ozone on the germ cells at specific meiotic stages. Results obtained from the cytological study explain the fecundity and fertility observations.

  11. Radiation-induced basal cell carcinoma

    PubMed Central

    Zargari, Omid

    2015-01-01

    Background: The treatment of tinea capitis using radiotherapy was introduced at the beginning of the twentieth century. A variety of cancers including basal cell carcinoma (BCC) are seen years after this treatment. Objective: We sought to determine the clinical characteristics of BCCs among irradiated patients. Methods: The clinical records of all patients with BCC in a clinic in north of Iran were reviewed. Results: Of the 58 cases of BCC, 29 had positive history for radiotherapy in their childhood. Multiple BCCs were seen in 79.3% and 10.3% of patients with history and without history of radiotherapy, respectively. Conclusions: X-ray radiation is still a major etiologic factor in developing BCC in northern Iran. Patients with positive history for radiotherapy have higher rate of recurrence.

  12. The use of gamma radiation for the elimination of Salmonella from frozen meat.

    PubMed

    Ley, F J; Kennedy, T S; Kawashima, K; Roberts, D; Hobbs, B C

    1970-06-01

    The use of a gamma radiation process for the elimination of Salmonella from frozen meat is considered with particular reference to the treatment of boned-out horsemeat and kangaroo meat imported into the UK and intended for use as pet meat.Examination of dose/survival curves produced for several serotypes of Salmonella in frozen meat shows that a radiation dose of 0.6 Mrad. will reduce a population by at least a factor of 10(5). The influence on the radiation resistance of salmonellas of such factors as preirradiation growth in the meat and temperature during irradiation have been examined and considered. It is also demonstrated with both preinoculated and naturally contaminated meat that postirradiation storage in the frozen state does not lead to the revival of irradiated salmonellas.The properties of Salmonella survivors deliberately produced in meat using conditions of irradiation designed to simulate a commercial process are studied after six recycling treatments through the process. There were no important changes in characteristics normally used for identification of Salmonella but radiation resistance was lowered. Survivors grown in situ in meat after irradiation showed an abnormally long lag phase, and removal of competitive microflora in meat by the radiation treatment can influence the growth of salmonellas. PMID:4914090

  13. Effect of surface ion charge transfer on electric conductivity of gas-polymer heterogeneous structure in pulsed. gamma. radiation

    SciTech Connect

    Elokhin, A.P.; Makeev, S.N.; Filatov, N.F.

    1988-11-01

    The radiation electric conductivity of gas-polymer heterogeneous structures with plane-parallel geometry of the electrodes in pulsed ..gamma.. radiation in the 5 x 10/sup 3/-10/sup 5/ Gy x sec/sup -1/ dose rate range was analyzed in consideration of surface ion charge transfer. An analytical expression was obtained for the radiation leakage current and it can be used in solving practical problems.

  14. Gamma spectroscopic measurements using the PID350 pixelated CdTe radiation detector

    E-print Network

    Karafasoulis, K; Seferlis, S; Papadakis, I; Loukas, D; Lambropoulos, C; Potiriadis, C

    2010-01-01

    Spectroscopic measurements are presented using the PID350 pixelated gamma radiation detectors. A high-speed data acquisition system has been developed in order to reduce the data loss during the data reading in case of a high flux of photons. A data analysis framework has been developed in order to improve the resolution of the acquired energy spectra, using specific calibration parameters for each PID350's pixel. Three PID350 detectors have been used to construct a stacked prototype system and spectroscopic measurements have been performed in order to test the ability of the prototype to localize radioactive sources.

  15. Gamma spectroscopic measurements using the PID350 pixelated CdTe radiation detector

    E-print Network

    K. Karafasoulis; K. Zachariadou; S. Seferlis; I. Papadakis; D. Loukas; C. Lambropoulos; C. Potiriadis

    2010-11-15

    Spectroscopic measurements are presented using the PID350 pixelated gamma radiation detectors. A high-speed data acquisition system has been developed in order to reduce the data loss during the data reading in case of a high flux of photons. A data analysis framework has been developed in order to improve the resolution of the acquired energy spectra, using specific calibration parameters for each PID350's pixel. Three PID350 detectors have been used to construct a stacked prototype system and spectroscopic measurements have been performed in order to test the ability of the prototype to localize radioactive sources.

  16. Energy response of agar-alanine phantom dosimeter to gamma radiation

    SciTech Connect

    Ciesielski, B.; Wielopolski, L.; Reinstein, L.E.

    1988-05-01

    Calculations of the energy response of an electron paramagnetic resonance (EPR) signal induced by gamma radiation in an agar-alanine phantom dosimeter are presented. Theoretically calculated slopes of the EPR signal calibration lines are comparable with those obtained experimentally for low-(50 kVp), medium-(662 keV), and high-(15 MVp) energy photons. The sensitivity of the phantom dosimeter (EPR signal amplitude/Gray) varies less than 2% within the 150- to 20-MeV energy range. For energies above 150 keV, the influence of variations in the size of alanine crystals is negligible.

  17. Determining the Impact of Concrete Roadways on Gamma Ray Background Readings for Radiation Portal Monitoring Systems

    E-print Network

    Ryan, Christopher Michael

    2012-07-16

    to the background of the detectors.18 II.B. Gamma ray interactions While there are more than 3,000 known nuclides, only about 270 of them are stable.19 The rest are radioactive and decay into other nuclides by emitting radiation. There are at least nine...% Iraq; 2% Canada; 3% United States; 20% Other FSU Countries; 7% Kazakhstan; 5% Ukraine; 5% Russia; 24% Remainder; 26% 4 Many USG assistance programs provide RPMs for use at POEs to intercept smuggled nuclear material. RPMs are designed...

  18. Induction of mutations resistant to maize dwarf mosaic virus in Sorghum bicolor using gamma radiation

    E-print Network

    Pye, Quentin Niel

    1977-01-01

    rility in advanced generations. The NDMV snd charcoal rot, a soil- b fl K, ~Nh I ph 11 (II bl. ) A@i y, d t b1 since some MDNV resistant plants were harvested only if they were also charcoal zot resistant. The 50 krad level seems to have an Frequency... found among any of the culivars emmined in the electron microscopy study. The effects of gamma radiation were shown to increase linearly up to the 3$ krad level and curvilinearly beyond this dose with each increase in dose for M field emergence...

  19. Spectral analysis of paramagnetic centers induced in human tooth enamel by x-rays and gamma radiation

    NASA Astrophysics Data System (ADS)

    Kirillov, V. A.; Kuchuro, I. I.

    2010-03-01

    Based on study of spectral and relaxation characteristics, we have established that paramagnetic centers induced in tooth enamel by x-rays and gamma radiation are identical in nature. We show that for the same exposure dose, the intensity of the electron paramagnetic resonance (EPR) signal induced by x-radiation with effective energy 34 keV is about an order of magnitude higher than the amplitude of the signal induced by gamma radiation. We have identified a three-fold attenuation of the EPR signal along the path of the x-radiation from the buccal to the lingual side of a tooth, which is evidence that the individual had undergone diagnostic x-ray examination of the dentition or skull. We have shown that the x-ray exposure doses reconstructed from the EPR spectra are an order of magnitude higher than the applied doses, while the dose loads due to gamma radiation are equal to the applied doses. The data obtained indicate that for adequate reconstruction of individual absorbed doses from EPR spectra of tooth enamel in the population subjected to the combined effect of x-radiation and accidental external gamma radiation as a result of the disaster at the Chernobyl nuclear power plant, we need to take into account the contribution to the dose load from diagnostic x-rays in examination of the teeth, jaw, or skull.

  20. Gamma tocotrienol, a potent radioprotector, preferentially upregulates expression of anti-apoptotic genes to promote intestinal cell survival.

    PubMed

    Suman, Shubhankar; Datta, Kamal; Chakraborty, Kushal; Kulkarni, Shilpa S; Doiron, Kathryn; Fornace, Albert J; Sree Kumar, K; Hauer-Jensen, Martin; Ghosh, Sanchita P

    2013-10-01

    Gamma tocotrienol (GT3) has been reported as a potent ameliorator of radiation-induced gastrointestinal (GI) toxicity when administered prophylactically. This study aimed to evaluate the role of GT3 mediated pro- and anti-apoptotic gene regulation in protecting mice from radiation-induced GI damage. Male 10- to 12-weeks-old CD2F1 mice were administered with a single dose of 200 mg/kg of GT3 or equal volume of vehicle (5% Tween-80) 24 h before exposure to 11 Gy of whole-body ?-radiation. Mouse jejunum was surgically removed 4 and 24h after radiation exposure, and was used for PCR array, histology, immunohistochemistry, and immunoblot analysis. Results were compared among vehicle pre-treated no radiation, vehicle pre-treated irradiated, and GT3 pre-treated irradiated groups. GT3 pretreated irradiated groups, both 4h and 24h after radiation, showed greater upregulation of anti-apoptotic gene expression than vehicle pretreated irradiated groups. TUNEL staining and intestinal crypt analysis showed protection of jejunum after GT3 pre-treatment and immunoblot results were supportive of PCR data. Our study demonstrated that GT3-mediated protection of intestinal cells from a GI-toxic dose of radiation occurred via upregulation of antiapoptotic and downregulation of pro-apoptotic factors, both at the transcript as well as at the protein levels. PMID:23941772

  1. Disruption of epithelial gamma delta T cell repertoires by mutation of the Syk tyrosine kinase.

    PubMed Central

    Mallick-Wood, C A; Pao, W; Cheng, A M; Lewis, J M; Kulkarni, S; Bolen, J B; Rowley, B; Tigelaar, R E; Pawson, T; Hayday, A C

    1996-01-01

    Chimeric mice in which lymphocytes are deficient in the Syk tyrosine kinase have been created. Compared with Syk-positive controls, mice with Syk -/- lymphocytes display substantial depletion of intraepithelial gamma delta T cells in the skin and gut, with developmental arrest occurring after antigen receptor gene rearrangement. In this dependence on Syk, subsets of intraepithelial gamma delta T cells are similar to B cells, but distinct from splenic gamma delta T cells that develop and expand in Syk-deficient mice. The characteristic associations of certain T-cell receptor V gamma/V delta gene rearrangements with specific epithelia are also disrupted by Syk deficiency. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 Fig. 6 PMID:8790395

  2. Space solar cells - High efficiency and radiation damage

    NASA Technical Reports Server (NTRS)

    Brandhorst, H. W., Jr.; Bernatowicz, D. T.

    1980-01-01

    The proceedings of the Third Solar Cell High Efficiency and Radiation Damage Meeting are outlined. The topics covered included high efficiency silicon solar cells, silicon solar cell radiation damage, GaAs solar cell performance, and 30 percent conversion devices. The study of radiation damage from a fundamental defect-centered basis is discussed and evaluated as a focus of future work. 18% AM0 efficiency and 0.7 V open-circuit voltages are designated as achievable goals for silicon solar cells, and the potential for 30% AM0 efficiencies from monolithic tandem cell designs without sunlight concentration is noted. In addition to its potential for 20% AM0 efficiencies, the GaAs cell offers the possibility of a radiation-insensitive power supply when operated at temperatures near 200 C.

  3. Calcium Protects Differentiating Neuroblastoma Cells during 50 Hz Electromagnetic Radiation

    Microsoft Academic Search

    R. Tonini; Baroni E. Masala; E. Masala; M. Micheletti; A. Ferroni; M. Mazzanti

    2001-01-01

    Despite growing concern about electromagnetic radiation, the interaction between 50- to 60-Hz fields and biological structures remains obscure. Epidemiological studies have failed to prove a significantly correlation between exposure to radiation fields and particular pathologies. We demonstrate that a 50- to 60-Hz magnetic field interacts with cell differentiation through two opposing mechanisms: it antagonizes the shift in cell membrane surface

  4. Development of human epithelial cell systems for radiation risk assessment

    Microsoft Academic Search

    C. H. Yang; L. M. Craise

    1994-01-01

    The most important health effect of space radiation for astronauts is cancer induction. For radiation risk assessment, an understanding of carcinogenic effect of heavy ions in human cells is most essential. In our laboratory, we have successfully developed a human mammary epithelial cell system for studying the neoplastic transformation in vitro. Growth variants were obtained from heavy ion irradiated immortal

  5. Drug and radiation resistance in spheroids: cell contact and kinetics

    Microsoft Academic Search

    Peggy L. Olive; Ralph E. Durand

    1994-01-01

    Cells from multicellular spheroids are often more resistant than monolayers to drugs and radiation. While explanations for resistance can be based on differences in cell cycle distribution, inability of the drug to penetrate the spheroid, or the presence of hypoxic cells, these mechanisms do not adequately explain resistance to all agents. Small spheroids (containing about 25–50 cells) exposed to ionizing

  6. Radiation Response of Cancer Stem-Like Cells From Established Human Cell Lines After Sorting for Surface Markers

    SciTech Connect

    Al-Assar, Osama; Muschel, Ruth J.; Mantoni, Tine S.; McKenna, W. Gillies [CR-UK, MRC Gray Institute for Radiation Oncology and Biology, University of Oxford, Churchill Hospital, Oxford OX3 7LJ (United Kingdom); Brunner, Thomas B., E-mail: thomas.brunner@rob.ox.ac.u [CR-UK, MRC Gray Institute for Radiation Oncology and Biology, University of Oxford, Churchill Hospital, Oxford OX3 7LJ (United Kingdom)

    2009-11-15

    Purpose: A subpopulation of cancer stem-like cells (CSLC) is hypothesized to exist in different cancer cell lines and to mediate radioresistance in solid tumors. Methods and Materials: Cells were stained for CSLC markers and sorted (fluorescence-activated cell sorter/magnetic beads) to compare foci and radiosensitivity of phosphorylated histone H2AX at Ser 139 (gamma-H2AX) in sorted vs. unsorted populations in eight cell lines from different organs. CSLC properties were examined using anchorage-independent growth and levels of activated Notch1. Validation consisted of testing tumorigenicity and postirradiation enrichment of CSLC in xenograft tumors. Results: The quantity of CSLC was generally in good agreement with primary tumors. CSLC from MDA-MB-231 (breast) and Panc-1 and PSN-1 (both pancreatic) cells had fewer residual gamma-H2AX foci than unsorted cells, pointing to radioresistance of CSLC. However, only MDA-MB-231 CSLC were more radioresistant than unsorted cells. Furthermore, MDA-MB-231 CSLC showed enhanced anchorage-independent growth and overexpression of activated Notch1 protein. The expression of cancer stem cell surface markers in the MDA-MB-231 xenograft model was increased after exposure to fractionated radiation. In contrast to PSN-1 cells, a growth advantage for MDA-MB-231 CSLC xenograft tumors was found compared to tumors arising from unsorted cells. Conclusions: CSLC subpopulations showed no general radioresistant phenotype, despite the quantities of CSLC subpopulations shown to correspond relatively well in other reports. Likewise, CSLC characteristics were found in some but not all of the tested cell lines. The reported problems in testing for CSLC in cell lines may be overcome by additional techniques, beyond sorting for markers.

  7. Breeding biology of Tree Swallows and House Wrens in a gradient of gamma radiation

    SciTech Connect

    Zach, R.; Mayoh, K.R.

    1982-12-01

    In a gradient of gamma radiation from 38.7 mC kg/sup -1/.d/sup -1/ to background levels of 0.05 ..mu..C. kg/sup -1/ . d/sup -1/ to background levels of 0.05 ..mu..C . kg/sup -1/ . d/sup -1/, Tree Swallows (Iridoprocne bicolor) and House Wrens (Troglodytes aedon) avoided nesting in areas of high radiation. Nest boxes selected by swallows and wrens had a mean exposure rate of only 9.3 and 6.6 ..mu..C . kg/sup -1/ . d/sup -1/, respectively. Lateral and canopy vegetation indices and nest hole height and direction could not explain the observed pattern of box selection. Of the boxes with low exposure rates, swallows selected those with little vegetation cover, whereas wrens chose boxes and heavy cover. It appears that the birds responded to radiation levels as low as 100 times background, but it is not clear whether they actually detected radiation or simply responded to secondary clues. The number of swallows and wrens fledged per box was unrelated to radiation exposure. The same was true for number of eggs, hatching success, fledging success, incubation time, and nestling time. Breeding success was reduced because of infertile eggs, eggs with dead embryos, cracked eggs, predation, adverse weather, abandonment, and parasites. The logistic model was ideally suited for describing gains in mass in nestling swallows and wrens. Growth of nestlings was not related to radiation exposure as indicated by the growth rate constant, asymptotic mass, and the proportion of variation explained by the logistic model. Breeding and growth performance were similar in studies not involving experimental radiation.

  8. Breeding biology of tree swallows and house wrens in a gradient of gamma radiation

    SciTech Connect

    Zach, R.; Mayoh, K.R.

    1982-12-01

    In a gradient of gamma radiation ranging from 38.7 mC.kg/sup -1/.d/sup -1/ to background levels of 0.05 ..mu..C.kg/sup -1/.d/sup -1/, Tree Swallows (Iridoprocne bicolor) and House Wrens (Troglodytes aedon) avoided nesting in areas of high radiation. Nest boxes selected by swallows and wrens had a mean exposure rate of only 9.3 and 6.6 ..mu..C.kg/sup -1/.d/sup -1/, respectively. Lateral and canopy vegetation indices and nest hole height and direction could not explain the observed pattern of box selection. Of the boxes with low exposure rates, swallows selected those with little vegetation cover, whereas wrens chose boxes with heavy cover. It appears that the birds responded to radiaton levels as low as 100 times background but it is not clear whether they actually detected radiation or simply responded to secondary clues. The number of swallows and wrens fledged per box was unrelated to radiation exposure. The same was true for number of eggs, hatching success, fledging success, incubation time, and nestling time. Breeding success was reduced because of infertile eggs, eggs with dead embryos, cracked eggs, predation, adverse weather, abandonment, and parasites. The logistic model was ideally suited for describing gains in mass in nestling swallows and wrens. Growth of nestlings was not related to radiation exposure as indicated by the growth rate constant, asymptotic mass, and the proportion of variation explained by the logistic model. The data show that birds avoided adverse effects of radiation by judicious box selection. However, there were indications that at higher breeding densities birds may use high-exposure boxes, where breeding success or growth of nestlings may become reduced due to radiation.

  9. A meta-analysis of leukaemia risk from protracted exposure to low-dose gamma radiation

    PubMed Central

    Schubauer-Berigan, M K

    2010-01-01

    Context More than 400?000 workers annually receive a measurable radiation dose and may be at increased risk of radiation-induced leukaemia. It is unclear whether leukaemia risk is elevated with protracted, low-dose exposure. Objective We conducted a meta-analysis examining the relationship between protracted low-dose ionising radiation exposure and leukaemia. Data sources Reviews by the National Academies and United Nations provided a summary of informative studies published before 2005. PubMed and Embase databases were searched for additional occupational and environmental studies published between 2005 and 2009. Study selection We selected 23 studies that: (1) examined the association between protracted exposures to ionising radiation and leukaemia excluding chronic lymphocytic subtype; (2) were a cohort or nested case–control design without major bias; (3) reported quantitative estimates of exposure; and (4) conducted exposure–response analyses using relative or excess RR per unit exposure. Methods Studies were further screened to reduce information overlap. Random effects models were developed to summarise between-study variance and obtain an aggregate estimate of the excess RR at 100?mGy. Publication bias was assessed by trim and fill and Rosenthal's file drawer methods. Results We found an ERR at 100?mGy of 0.19 (95% CI 0.07 to 0.32) by modelling results from 10 studies and adjusting for publication bias. Between-study variance was not evident (p=0.99). Conclusions Protracted exposure to low-dose gamma radiation is significantly associated with leukaemia. Our estimate agreed well with the leukaemia risk observed among exposed adults in the Life Span Study (LSS) of atomic bomb survivors, providing increased confidence in the current understanding of leukaemia risk from ionising radiation. However, unlike the estimates obtained from the LSS, our model provides a precise, quantitative summary of the direct estimates of excess risk from studies of protracted radiation exposures. PMID:20935290

  10. Space radiation environmental testing on POSS coated solar cell coverglass

    Microsoft Academic Search

    Simon H. Liu; Jennifer E. Granata; Michael J. Meshishnek; Martin R. Ciofalo; Edward J. Simburger

    2008-01-01

    Light weight, flexible, radiation hardened solar cells coatings are of interest for applications on satellite power generation owing to the potential advantages in terms of having higher specific power (lightweight), lower specific volume (flexible), and higher end-of-life power (superior radiation resistance), as compared to current state-of-the-art Ce-doped micro sheet solar cell coverglass. The space radiation environment causes gradual optical performance

  11. Effects of Gamma Radiation on Individual and Mixed Ion Exchange Resins

    SciTech Connect

    Baumann, E.W.

    2003-01-06

    The ion exchange resins that are used to deionize moderator in the reactor purification systems may accumulate sufficient radiation dose to damage the resins. This radiation damage would be manifested by: (1) loss of useful exchange capacity of the bed, which is costly since resins from the reactor deionizers are not reused; (2) shrinking or swelling of the resins, which may have some effect on the hydraulic behavior of the beds; (3) release of resin degradation products into the process stream, which pollutes moderator with impurities and precursors of the neutron-induced radioisotopes. This document details results of a laboratory study to determine the magnitude of these three effects by gamma irradiation of individual resins and their mixtures.

  12. Influence of gamma radiation on hindered phenols in LDPE, paraffin oil and paraffin wax

    NASA Astrophysics Data System (ADS)

    Ahmed, Shamshad; Yasin, Tariq; Ghaffar, Abdul

    2003-12-01

    Extraction and high performance liquid chromatography procedures have been developed for the determination of two hindered phenols—Irganox-1010 and Santonox ®, incorporated in low density polyethylene (LDPE), paraffin oil and paraffin wax at varied concentrations. These blends were gamma irradiated from 25 to 400 kGy and the radiation and thermal stability of the antioxidant under the experimental conditions has been determined. Upon increase in radiation dose from 25 to 400 kGy, a gradual diminution in the extractable level of each antioxidant was observed. The fate of both the antioxidants in various matrices has been compared. It has been shown that both the antioxidants can influence the polyethylene network formation and the radical yield in different ways resulting in retardation in the rate of crosslinking, as determined by gel-content analysis.

  13. Interaction of razoxane and radiation on cultured Chinese hamster cells.

    PubMed

    Kimler, B F

    1982-08-01

    Razoxane [(+/-)-1,2-bis(3,5-dioxopiperazine-1-yl)propane] was investigated for its effects on the survival of irradiated Chinese hamster fibroblasts in vitro. Razoxane alone produced cytotoxicity that was dependent upon drug concentration and pulse exposure time, with a preferential lethality for cells treated while in the DNA-synthetic phase. Razoxane enhanced radiation-induced cell killing when used as either a pulse exposure or a continuous treatment. In asynchronous populations of cells, this was expressed as an increase in the slope and a reduction in the shoulder of the radiation dose-survival curve. In synchronous populations of cells, a modest increase in cell killing was observed for those cells treated in G1 and G2, with a greater enhancement for cells treated in the S-phase. Overall, razoxane may potentiate the radiation-induced killing of cultured mammalian cells by a number of mechanisms: 1) a blockade of cell cycle progression causing an accumulation of cells in radiosensitive phases of the cell cycle; 2) selective cytotoxicity of cells in radioresistant phases of the cell cycle; 3) inhibition of the accumulation of sublethal radiation damage; or 4) interaction of the damages induced by each agent so as to produce an enhanced effect. These mechanisms may need to be considered if razoxane and radiation therapy are to be used in combined modality therapeutic approaches. PMID:7141912

  14. Repair processes and radiation quality in neoplastic transformation of mammalian cells

    SciTech Connect

    Han, A.; Hill, C.K.; Elkind, M.M.

    1984-08-01

    Appropriate in vitro mammalian cell systems facilitate the study of cellular mechanisms of radiation oncogenesis. C3H 10T1/2 cells derived from mouse embryo have been used to study the effects of protracted irradiation on cell killing and incidence of neoplastic transformation. Protracted exposures of /sup 60/Co ..gamma.. rays or fission-spectrum neutrons (from the JANUS reactor at the Argonne National Laboratory) were given either at low dose rates or as multifractionated regimens using high dose rates. Dose protraction of ..gamma.. rays by multifractionation at a high dose rate (50 rad/min) results in appreciable reduction in cell killing and also significantly reduces the incidence of neoplastic transformation. Irradiation at a low dose rate has the same qualitative effect. In contrast, protracted exposures of fission-spectrum neutrons, given at a low dose rate (0.086 or 0.43 rad/min), result in significant enhancement of the frequency of transformation in the dose region of up to 80 rad. However, the survival of cells is essentially the same as that for the same single dose of neutrons given at a high dose rate. These observations are consistent with net ''error-free'' repair of transformational damage following protracted exposure of a low LET radiation and possibly a net ''error-prone'' repair of transformational damage after protracted irradiations with fission-spectrum neutrons.

  15. Dendritic cells and NK cells stimulate bystander T cell activation in response to TLR agonists through secretion of IFN-alpha beta and IFN-gamma.

    PubMed

    Kamath, Arun T; Sheasby, Christopher E; Tough, David F

    2005-01-15

    Recognition of conserved features of infectious agents by innate pathogen receptors plays an important role in initiating the adaptive immune response. We have investigated early changes occurring among T cells after injection of TLR agonists into mice. Widespread, transient phenotypic activation of both naive and memory T cells was observed rapidly after injection of molecules acting through TLR3, -4, -7, and -9, but not TLR2. T cell activation was shown to be mediated by a combination of IFN-alphabeta, secreted by dendritic cells (DCs), and IFN-gamma, secreted by NK cells; notably, IFN-gamma-secreting NK cells expressed CD11c and copurified with DCs. Production of IFN-gamma by NK cells could be stimulated by DCs from TLR agonist-injected mice, and although soluble factors secreted by LPS-stimulated DCs were sufficient to induce IFN-gamma, maximal IFN-gamma production required both direct contact of NK cells with DCs and DC-secreted cytokines. In vitro, IFN-alphabeta, IL-18, and IL-12 all contributed to DC stimulation of NK cell IFN-gamma, whereas IFN-alphabeta was shown to be important for induction of T cell bystander activation and NK cell IFN-gamma production in vivo. The results delineate a pathway involving innate immune mediators through which TLR agonists trigger bystander activation of T cells. PMID:15634897

  16. Radiation damage and repair in cells and cell components. Part 2. Physical radiations and biological significance. Final report

    SciTech Connect

    Fluke, D.J.

    1984-08-01

    The report comprises a teaching text, encompassing all physical radiations likely to be of biological interest, and the relevant biological effects and their significance. Topics include human radiobiology, delayed effects, radiation absorption in organisms, aqueous radiation chemistry, cell radiobiology, mutagenesis, and photobiology. (ACR)

  17. Characterization of x- and gamma- radiation in relativistically intense laser-solid interactions

    NASA Astrophysics Data System (ADS)

    Hou, Bixue; Zulick, Calvin; Zhao, Zhen; Nees, John; Batson, Thomas; Maksimchuk, Anatoly; Thomas, Alexander G. R.; Krushelnick, Karl; Center for Ultrafast Optical Science Team

    2013-10-01

    Using a high resolution (?/ ?? > 100) high purity germanium detector, the angular and material dependence, and the intensity scaling, of bremsstrahlung gamma radiation from relativistically intense (I > 1018 W/cm2) laser-solid interactions have been characterized at energies between 0.1 and 1 MeV with the high-repetition rate (500 Hz) Lambda-Cubed laser facility. The bremsstrahlung spectra of SiO2, Mo, and Eu2O3 were observed to have two-temperature energy distributions, corresponding to two different groups of electrons and depending on both laser intensity and observation angle. The spectra and source sizes of hard x-radiation under 0.1 MeV are also studied. These x-ray sources are being developed for phase-contrast imaging. Using a high resolution (?/ ?? > 100) high purity germanium detector, the angular and material dependence, and the intensity scaling, of bremsstrahlung gamma radiation from relativistically intense (I > 1018 W/cm2) laser-solid interactions have been characterized at energies between 0.1 and 1 MeV with the high-repetition rate (500 Hz) Lambda-Cubed laser facility. The bremsstrahlung spectra of SiO2, Mo, and Eu2O3 were observed to have two-temperature energy distributions, corresponding to two different groups of electrons and depending on both laser intensity and observation angle. The spectra and source sizes of hard x-radiation under 0.1 MeV are also studied. These x-ray sources are being developed for phase-contrast imaging. Support provided by DHS (EECS-0833499), AFOSR (FA99550-12-1-0310), ARO (W911NF-11-1-0116).

  18. Lactic acid bacterial cell factories for gamma-aminobutyric acid

    Microsoft Academic Search

    Haixing Li; Yusheng Cao

    2010-01-01

    Gamma-aminobutyric acid is a non-protein amino acid that is widely present in organisms. Several important physiological functions\\u000a of gamma-aminobutyric acid have been characterized, such as neurotransmission, induction of hypotension, diuretic effects,\\u000a and tranquilizer effects. Many microorganisms can produce gamma-aminobutyric acid including bacteria, fungi and yeasts. Among\\u000a them, gamma-aminobutyric acid-producing lactic acid bacteria have been a focus of research in recent

  19. Gelam honey attenuated radiation-induced cell death in human diploid fibroblasts by promoting cell cycle progression and inhibiting apoptosis

    PubMed Central

    2014-01-01

    Background The interaction between ionizing radiation and substances in cells will induce the production of free radicals. These free radicals inflict damage to important biomolecules such as chromosomes, proteins and lipids which consequently trigger the expression of genes which are involved in protecting the cells or repair the oxidative damages. Honey has been known for its antioxidant properties and was used in medical and cosmetic products. Currently, research on honey is ongoing and diversifying. The aim of this study was to elucidate the role of Gelam honey as a radioprotector in human diploid fibroblast (HDFs) which were exposed to gamma-rays by determining the expression of genes and proteins involved in cell cycle regulation and cell death. Methods Six groups of HDFs were studied viz. untreated control, irradiated HDFs, Gelam honey-treated HDFs and HDF treated with Gelam honey pre-, during- and post-irradiation. HDFs were treated with 6 mg/ml of sterilized Gelam honey (w/v) for 24 h and exposed to 1 Gray (Gy) of gamma-rays at the dose rate of 0.25 Gy/min. Results Our findings showed that, gamma-irradiation at 1 Gy up-regulated ATM, p53, p16ink4a and cyclin D1 genes and subsequently initiated cell cycle arrest at G0/G1 phase and induced apoptosis (p?cell cycle profile showed that cells progressed to S phase with less percentage of cells in G0/G1 phase with Gelam honey treatment while apoptosis was inhibited. Conclusion Gelam honey acts a radioprotector against gamma-irradiation by attenuating radiation-induced cell death. PMID:24655584

  20. Ab initio calculation of the $np \\to d \\gamma$ radiative capture process

    E-print Network

    Beane, Silas R; Detmold, William; Orginos, Kostas; Parreño, Assumpta; Savage, Martin J; Tiburzi, Brian C

    2015-01-01

    Lattice QCD calculations of two-nucleon systems are used to isolate the short-distance two-body electromagnetic contributions to the radiative capture process $np \\to d\\gamma$, and the photo-disintegration processes $\\gamma^{(\\ast)} d \\to np$. In nuclear potential models, such contributions are described by phenomenological meson-exchange currents, while in the present work, they are determined directly from the quark and gluon interactions of QCD. Calculations of neutron-proton energy levels in multiple background magnetic fields are performed at two values of the quark masses, corresponding to pion masses of $m_\\pi \\sim 450$ and 806 MeV, and are combined with pionless nuclear effective field theory to determine these low-energy inelastic processes. Extrapolating to the physical pion mass, a cross section of $\\sigma^{lqcd}(np\\to d\\gamma)=332.4({\\tiny \\begin{array}{l}+5.4 \\\\ - 4.7\\end{array}})\\ mb$ is obtained at an incident neutron speed of $v=2,200\\ m/s$, consistent with the experimental value of $\\sigma^{e...

  1. Aflatoxins and ochratoxin a reduction in black and white pepper by gamma radiation

    NASA Astrophysics Data System (ADS)

    Jalili, M.; Jinap, S.; Noranizan, M. A.

    2012-11-01

    Irradiation is an important means of decontamination of food commodities, especially spices. The aim of the current study was to investigate the efficacy of gamma radiation (60Co) for decontaminating ochratoxin A (OTA) and aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) residues in artificially contaminated black and white pepper samples. The moisture content of the pepper samples was set at 12% or 18%, and the applied gamma dose ranged from 5 to 30 kGy. Mycotoxin levels were determined by high-performance liquid chromatography (HPLC) after immunoaffinity column (IAC) chromatography. Both the gamma irradiation dose and moisture content showed significant effects (P<0.05) on mycotoxin reduction. The maximum toxin reductions, found at 18% moisture content and 30 kGy, were 55.2%, 50.6%, 39.2%, 47.7% and 42.9% for OTA, AFB1, AFB2, AFG1 and AFG2, respectively.

  2. Gamma radiation and dose rate investigations on the Adriatic islands of magmatic origin.

    PubMed

    Petrinec, Branko; Frani?, Zdenko; Leder, Nenad; Tsabaris, Christos; Bituh, Tomislav; Marovi?, Gordana

    2010-06-01

    Natural radioactivity of Middle-Adriatic Sea islands and islets was measured. Gamma spectrometric measurements, both in situ and in laboratory, as well as radon measurements in the seawater were performed. Activity concentrations and the associated dose rates due to naturally occurring (232)Th, (238)U and (40)K radioisotopes were determined. Dose rates calculated from in situ gamma spectrometry are in correlation with dose rates calculated from activity concentrations measured in collected samples of pebbles and rocks. In situ gamma ray spectrometry in the seawater has been performed, showing activity concentration of 220 and 240 Bq m(-3) for (214)Bi and (214)Pb, respectively due to the presence of magmatic rocks in the seabed. The radium equivalent activity varied from 13 to 53 Bq kg(-1). These values are lower than the limit values, indicating that the radiation hazard is not significant. The highest mean activity concentrations of naturally occurring radionuclides in rock samples collected were found on the islands of magmatic origin. PMID:20085897

  3. Effects of ionizing radiation (neutrons/gamma rays) on plasma lipids and lipoproteins in rats.

    PubMed

    Feurgard, C; Bayle, D; Guézingar, F; Sérougne, C; Mazur, A; Lutton, C; Aigueperse, J; Gourmelon, P; Mathé, D

    1998-07-01

    Male Wistar rats weighing 250 g were exposed to 4 Gy of neutrons/gamma radiation (3.33 Gy of neutrons and 0.66 Gy of gamma rays). After whole-body irradiation, plasma cholesterol and phospholipid levels increased up to 62 and 37%, respectively, at day 4 and then returned to control values 12 days after irradiation. Plasma triglyceride concentrations decreased concomitantly with decreased food intake after irradiation but remained higher than in pair-fed control rats. Plasma lipoproteins were separated by ultracentrifugation on a density gradient (1.006-1.210 g/ml). Four days after irradiation, most of the cholesterol (62% compared to 31% in controls, P < 0.001) is transported by apolipoprotein E-rich high-density lipoproteins. At the same time, plasma levels of apolipoproteins B and E were increased by 28 and 65%, respectively, while those of apolipoproteins AI and AIV were reduced by 21 and 59%, respectively. While in the liver of irradiated rats the apolipoprotein B/E receptor number was not modified, the hydroxymethylglutaryl coenzyme A reductase activity was fivefold higher than in control pair-fed rats. Four days after irradiation, the susceptibility of lipoproteins to peroxidation, as measured by the formation of conjugated dienes in the presence of Cu2+, was markedly increased while plasma vitamin E levels were decreased, demonstrating that irradiation reduces antioxidant stores markedly. These results suggest that such modified lipoproteins could be involved in radiation-induced vascular damage. PMID:9650601

  4. Prediction of radiation dosimetry in patients with thyroid cancer using a Gamma camera

    SciTech Connect

    De Nardo, G.L.; Macey, D.J.; De Nardo, S.J.; Adams, D.A.

    1985-05-01

    Radioiodine in the thyroid or cervical metastases, and therefore radiation dosimetry, can be determined using a probe and phantom. This approach is not ideal for quantitating radioiodine and dosimetry for sites elsewhere in the body. The authors have studied the use of gamma camera methods in association with I-123 to predict the distribution of I-131 and its dosimetry in 3 patients with metastatic thyroid cancer. Images and urine were obtained after administration of tracer I-123 and treatment I-131 to each patient. The geometric mean of counts from anterior and posterior total body camera scans were used to determine body clearance. Organ or metastasis radioactvity and dosimetry were quantitated using planar images and SPECT. Uptake, clearance and dosimetry of structures, such as thyroid and nodular metastases in the lung, could be determined. In summary, a gamma camera method for improved quantitation of radioiodine distribution in the body has been explored. It provides quantitative pharmacokinetics which give better estimates of distribution of radiation dose. This information offers a less empirical approach to the treatment of thyroid cancer with I-131, and other cancers with radiolabeled antibodies.

  5. Influence of gamma radiation on the gel rigidity index and binding capability of gelatin

    SciTech Connect

    Fassihi, A.R.; Parker, M.S.

    1988-10-01

    Changes in the rigidity indices of gelatin gel before and after gamma irradiation were characterized by dynamic mechanical testing, and the significance of these changes on the strength of granules was evaluated. Results illustrate the difficulty of obtaining reproducible values for gels containing less than 20% gelatin. However, rigidity indices for gels with a gelatin content of 20% and higher are consistent and may provide a useful controlling factor for preparation of gelatins of more precise specifications. The data indicate that rigidity degradation kinetics of several concentrations of gelatin gel at different radiation doses are complex, showing both increasing and decreasing rates. These findings strongly suggest that doses of less than 2.0 Mrad of gamma radiation should be used in order to obtain gelatins of acceptable quality for pharmaceutical applications. The crushing strength of granules of lactose powder granulated with irradiated gelatin reveals that the binding capability of such gelatin is significantly reduced. The results obtained for various size fractions and granule hardnesses containing different binder concentrations also suggest that particle size influences the granule strength to a lesser extent than does binder concentration and its consistency.

  6. Radiation damage and charge collection effects in Si(Li) gamma-ray detectors

    NASA Astrophysics Data System (ADS)

    Hull, Ethan L.; Pehl, Richard H.; Tindall, Craig; Luke, Paul N.; Kurfess, James D.

    2003-01-01

    The spectroscopy performance of 6-mm thick Si(Li) planar detectors was studied as a function of operating temperature and electric field. The energy resolution of the 662-keV gamma-ray peak from a 137Cs source was used to monitor the spectroscopy performance of the detectors. The efficiency, depletion voltage, leakage current, and noise were also monitored. The effects of radiation damage caused by 200-MeV protons were studied to determine the viability of operation in space. Four detectors, two maintained at 88 K and two maintained at 212 K, were irradiated to a fluence of 8.7×10 8 p/cm 2. No effects were observed. The two detectors irradiated at 212 K were subsequently irradiated with an additional 8.7×10 9 p/cm 2, again at 212 K. These detectors then exhibited slight energy resolution degradation. No other radiation damage effects were observed. The resolution degradation increased at higher operating temperature and decreased with higher electric field. Cycling the detectors to room temperature for 14 h eliminated the resolution degradation. The resolution of these detectors is limited by the combination of ballistic deficit and parallel noise in the ˜220 K range. A significant decrease in the gamma-ray peak count rate, almost certainly caused by surface channel effects, was the most dramatic temperature-dependent effect observed.

  7. Single-source gamma radiation procedures for improved calibration and measurements in porous media

    SciTech Connect

    Oostrom, M. [Pacific Northwest National Lab., Richland, WA (United States). Environmental Technology Div.] [Pacific Northwest National Lab., Richland, WA (United States). Environmental Technology Div.; Hofstee, C.; Dane, H. [Auburn Univ., AL (United States). Dept. of Agronomy and Soils] [Auburn Univ., AL (United States). Dept. of Agronomy and Soils; Lenhard, R.J. [Sultan Oaboos Univ. (Oman). Dept. of Soil and Water] [Sultan Oaboos Univ. (Oman). Dept. of Soil and Water

    1998-08-01

    When dual-energy gamma radiation systems are employed for measurements in porous media, count rates from both sources are often used to compute parameter values. However, for several applications, the count rates of just one source are insufficient. These applications include the determination of volumetric liquid content values in two-liquid systems and salt concentration values in water-saturated porous media. Single-energy gamma radiation procedures for three applications are described in this paper. Through an error analysis, single-source procedures are shown to reduce the probable error in the determinations considerably. Example calculations and simple column experiments were conducted for each application to compare the performance of the new single-source and standard dual-source methods. In all cases, the single-source methods provided more reliable data than the traditional dual-source methods. In addition, a single-source calibration procedure is proposed to determine incident count rates indirectly. This procedure, which requires packing under saturated conditions, can be used in all single- and dual-source applications and yields accurate porosity and dry bulk density values.

  8. The effect of perinatal sup 60 Co gamma radiation on brain weight in beagles

    SciTech Connect

    Hamilton, B.F.; Benjamin, S.A.; Angleton, G.M.; Lee, A.C. (Colorado State Univ., Fort Collins (USA))

    1989-08-01

    Beagle dogs were given single, whole-body {sup 60}Co gamma-radiation exposures at one of three prenatal (8, 28, or 55 days postcoitus) or three postnatal (2, 70, or 365 days postpartum) ages to evaluate the relative radiosensitivity of various stages of brain development. A total of 387 dogs received mean doses ranging from 0.16 to 3.83 Gy, and 120 dogs were sham-irradiated. Groups of dogs were sacrificed at preselected times from 70 days to 11 years of age. Brain weight decreased significantly with increasing dose in dogs irradiated at 28 or 55 days postcoitus or at 2 days postpartum. Irradiations at 28 days postcoitus were dramatically more effective in causing a reduction in brain weight than those at 55 days postcoitus or 2 days postpartum. Among dogs given 1.0 Gy or more and followed for up to 4 years, there was a radiation effect evident at all three sensitive exposure ages. Among dogs given lower doses and followed for up to 11 years, there was a significant decrease in brain weight in dogs given 0.80-0.88 Gy at 28 days postcoitus. All decreases in brain weight were present after normalization for radiation-induced reductions in skeletal (body) size. No specific morphologic changes were noted in the brains which showed the radiation-related reductions in size.

  9. 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.

  10. Effects of gamma radiation on hard dental tissues of albino rats using scanning electron microscope – Part 1

    Microsoft Academic Search

    Nabil El-Faramawy; Reham Ameen; Khaled El-Haddad; Ahmed Maghraby; Medhat El-Zainy

    2011-01-01

    In the present study, 40 adult male albino rats were used to study the effect of gamma radiation on the hard dental tissues (enamel surface, dentinal tubules and the cementum surface). The rats were irradiated at 0.2, 0.5, 1.0, 2.0, 4.0 and 6.0 Gy gamma doses. The effects of irradiated hard dental tissues samples were investigated using a scanning electron microscope.

  11. Pilot scale-up and shelf stability of hydrogel wound dressings obtained by gamma radiation

    NASA Astrophysics Data System (ADS)

    Soler, Dulce María; Rodríguez, Yanet; Correa, Hector; Moreno, Ailed; Carrizales, Lila

    2012-08-01

    This study is aimed of producing pilot batches of hydrogel wound dressings by gamma radiation and evaluating their shelf stability. Six batches of 3L capacity were prepared based on poly(vinyl pyrrolidone), agar and polyethylene glycol and they were dispensed in polyester trays, covered with polyester films and sealed in two types of materials: polyethylene bags and vacuum polyethylene bags. Dressings were formed in a single step process for the hydrogel formation and sterilization at 25-30 kGy gamma radiation dose in a JS-9500 Gamma Irradiator (Nordion, Canada). The six batches were initially physicochemical characterized in terms of dimensions and appearance, gel fraction, morphology analysis, hydrogel strength, moisture retention capability and swelling capacity. They were kept under two storage conditions: room temperature (T: 30±2 °C/RH: 70± 5%) and refrigerated temperature (T: 5±3 °C) during 24 months and sterility test was performed. The appearance of membranes was transparent, clear, uncut and flexible; the gel fraction of batches was higher than 75% and the hydrogel surface showed a porous structure. There was a slow decrease of the compression rate 20% until 7 h and about 70% at 24 h. Moisture retention capability in 5 h was similar for all the batches, about 40% and 60% at 37 °C and at room temperature respectively. The swelling of hydrogels in acidic media was strong and in alkaline media the weight variation remains almost stable until 24 h and then there is a loss of weight. The six batches remained sterile during the stability study in the conditions tested. The pilot batches were consistent from batch to batch and remained stable during 24 months.

  12. Effect of gamma radiation on the inactivation of aflatoxin B1 in food and feed crops

    PubMed Central

    Ghanem, I.; Orfi, M.; Shamma, M.

    2008-01-01

    Samples of food crops (peanut, peeled pistachio, unpeeled pistachio, rice, and corn) and feed (barley, bran, corn) were autoclave-sterilized, and inoculated with 106 of spore suspension of an isolate of Aspergillus flavus fungus known to produce aflatoxin B1 (AFB1) . Following a 10-day period of incubation at 27 C to allow for fungal growth, food and feed samples were irradiated with gamma radiation at the doses 4, 6, and 10 kGy. Results indicated that degradation of AFB1 was positively correlated with the increase in the applied dose of gamma ray for each tested sample. At a dose of 10 kGy percentages of AFB1 degradation reached highest values at 58.6, 68.8, 84.6, 81.1 and 87.8% for peanuts, peeled pistachios, unpeeled pistachios, corn and rice samples, respectively. In feed samples percentages of AFB1 degradation were 45, 66, and 90% in barley, 47, 75, and 86% in bran, and 31, 72, and 84% in corn for the doses of 4, 6, and 10 kGy, respectively. AFB1 degradation in food samples correlated negatively with oil content in irradiated samples. Thus, in peanuts, which contained the highest oil content, percentage of AFB1 degradation at 10 kGy was not more than 56.6%, whereas, the corresponding value in corn, which contained the lowest oil content, reached as high as 80%. The above results indicate the possibility of using gamma radiation as a means of degradation of AFB1 in food and feed crops to levels lower than the maximum allowed levels. PMID:24031308

  13. Galactic Center Gamma Ray Excess in a Radiative Neutrino Mass Model

    E-print Network

    Debasish Borah; Arnab Dasgupta

    2014-12-08

    The Fermi gamma ray space telescope data have pointed towards an excess of gamma rays with a peak around $1-3$ GeV in the region surrounding the galactic center. This anomalous excess can be described well by a dark matter candidate having mass in the range $31-40$ GeV annihilating into $b\\bar{b}$ pairs with a cross section of $ \\simeq (1.4-2.0) \\times 10^{-26} \\; \\text{cm}^3/\\text{s}$. In this work we explore the possibility of having such a dark matter candidate within the framework of a radiative neutrino mass model. The model is a simple extension of the standard model by an additional $U(1)_X$ gauge symmetry where the standard model neutrino masses arise both at tree level as well as radiatively by the anomaly free addition of one singlet fermion $N_R$ and two triplet fermions $\\Sigma_{1R}, \\Sigma_{2R}$ with suitable Higgs scalars. The spontaneous gauge symmetry breaking is achieved in such a way which results in a residual $Z_2$ symmetry and hence providing a stable cold dark matter candidate. We show that the singlet fermionic dark matter candidate in our model can give rise to the galactic center gamma ray excess. The parameter space which simultaneously satisfy the constraints on relic density, direct detection scattering as well as collider bounds essentially corresponds to an s-wave resonance where the gauge boson mass $m_X$ is approximately twice that of dark matter mass $m_{\\chi}$. We also discuss the compatibility of such a light fermion singlet dark matter with light neutrino mass.

  14. Biological response of cancer cells to radiation treatment

    PubMed Central

    Baskar, Rajamanickam; Dai, Jiawen; Wenlong, Nei; Yeo, Richard; Yeoh, Kheng-Wei

    2014-01-01

    Cancer is a class of diseases characterized by uncontrolled cell growth and has the ability to spread or metastasize throughout the body. In recent years, remarkable progress has been made toward the understanding of proposed hallmarks of cancer development, care, and treatment modalities. Radiation therapy or radiotherapy is an important and integral component of cancer management, mostly conferring a survival benefit. Radiation therapy destroys cancer by depositing high-energy radiation on the cancer tissues. Over the years, radiation therapy has been driven by constant technological advances and approximately 50% of all patients with localized malignant tumors are treated with radiation at some point in the course of their disease. In radiation oncology, research and development in the last three decades has led to considerable improvement in our understanding of the differential responses of normal and cancer cells. The biological effectiveness of radiation depends on the linear energy transfer (LET), total dose, number of fractions and radiosensitivity of the targeted cells or tissues. Radiation can either directly or indirectly (by producing free radicals) damages the genome of the cell. This has been challenged in recent years by a newly identified phenomenon known as radiation induced bystander effect (RIBE). In RIBE, the non-irradiated cells adjacent to or located far from the irradiated cells/tissues demonstrate similar responses to that of the directly irradiated cells. Understanding the cancer cell responses during the fractions or after the course of irradiation will lead to improvements in therapeutic efficacy and potentially, benefitting a significant proportion of cancer patients. In this review, the clinical implications of radiation induced direct and bystander effects on the cancer cell are discussed. PMID:25988165

  15. Tumor Cell Response to Synchrotron Microbeam Radiation Therapy Differs Markedly From Cells in Normal Tissues

    SciTech Connect

    Crosbie, Jeffrey C. [School of Physics, Monash University, Clayton, Victoria (Australia); Monash Centre for Synchrotron Science, Monash University, Clayton, Victoria (Australia); Centre for Women's Health Research, Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria (Australia); William Buckland Radiotherapy Centre, Alfred Hospital, Melbourne (Australia); Anderson, Robin L. [PeterMacCallum Cancer Centre, Melbourne (Australia); Department of Pathology, University of Melbourne (Australia); Rothkamm, Kai [Health Protection Agency, Radiation Protection Division, Oxfordshire (United Kingdom); Restall, Christina M. [PeterMacCallum Cancer Centre, Melbourne (Australia); Cann, Leonie [Centre for Women's Health Research, Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria (Australia); Ruwanpura, Saleela [Monash Institute of Medical Research, Monash University, Clayton, Victoria (Australia); Meachem, Sarah [Prince Henry's Institute of Medical Research, Clayton, Victoria (Australia); Yagi, Naoto [Research and Utilisation Division, JASRI, SPring-8, Mikazuki-cho, Sayo-gun, Hyogo (Japan); Svalbe, Imants [School of Physics, Monash University, Clayton, Victoria (Australia); Lewis, Robert A. [School of Physics, Monash University, Clayton, Victoria (Australia); Monash Centre for Synchrotron Science, Monash University, Clayton, Victoria (Australia); Williams, Bryan R.G. [Monash Institute of Medical Research, Monash University, Clayton, Victoria (Australia); Rogers, Peter A.W., E-mail: Peter.Rogers@med.monash.edu.a [Centre for Women's Health Research, Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria (Australia)

    2010-07-01

    Purpose: High-dose synchrotron microbeam radiation therapy (MRT) can be effective at destroying tumors in animal models while causing very little damage to normal tissues. The aim of this study was to investigate the cellular processes behind this observation of potential clinical importance. Methods and Materials: MRT was performed using a lattice of 25 {mu}m-wide, planar, polychromatic, kilovoltage X-ray microbeams, with 200-{mu}m peak separation. Inoculated EMT-6.5 tumor and normal mouse skin tissues were harvested at defined intervals post-MRT. Immunohistochemical detection of {gamma}-H2AX allowed precise localization of irradiated cells, which were also assessed for proliferation and apoptosis. Results: MRT significantly reduced tumor cell proliferation by 24 h post-irradiation (p = 0.002). An unexpected finding was that within 24 h of MRT, peak and valley irradiated zones were indistinguishable in tumors because of extensive cell migration between the zones. This was not seen in MRT-treated normal skin, which appeared to undergo a coordinated repair response. MRT elicited an increase in median survival times of EMT-6.5 and 67NR tumor-inoculated mice similar to that achieved with conventional radiotherapy, while causing markedly less normal tissue damage. Conclusions: This study provides evidence of a differential response at a cellular level between normal and tumor tissues after synchrotron MRT.

  16. An investigation on the radiation sensitivity of DNA conformations to 60Co gamma rays by using Geant4 toolkit

    NASA Astrophysics Data System (ADS)

    Semsarha, F.; Goliaei, B.; Raisali, G.; Khalafi, H.; Mirzakhanian, L.

    2014-03-01

    To investigate the impact of conformational properties of genetic material of living cells on radiation-induced DNA damage, single strand breaks (SSB), double strand breaks (DSB) and some microdosimetric quantities of A, B and Z-DNA conformations caused by 60Co gamma rays, have been calculated. Based on a previous B-DNA geometrical model, models of A and Z forms have been developed. Simple 34 base pairs segments of each model repeated in high number and secondary electron spectrum of 60Co gamma rays have been simulated in a volume of a typical animal cell nucleus. All simulations in this study have been performed by using the Geant4 (GEometry ANd Tracking 4)-DNA extension of the Geant4 toolkit. The results showed that, B-DNA has the lowest yield of simple strand breaks with 2.23 × 10-10 Gy-1 Da-1 and 1.0 × 10-11 Gy-1 Da-1 for the SSB and DSB damage yield, respectively. The A-DNA has the highest SSB yield with 3.59 × 10-10 Gy-1 Da-1 and the Z-DNA has the highest DSB yields with 1.8 × 10-11 Gy-1 Da-1. It has been concluded that there is a direct correlation between the hit probability, mean specific imparted energy and SSB yield in each model of DNA. Moreover, there is a direct correlation between the DSB yield and both the mean lineal energy and topological characteristics of each model.

  17. Orally Administered Fructose Increases the Numbers of Peripheral Lymphocytes Reduced by Exposure of Mice to Gamma or SPE-like Proton Radiation

    PubMed Central

    Romero-Weaver, A.L.; Ni, J.; Lin, L.; Kennedy, A.R.

    2014-01-01

    Exposure of the whole body or a major portion of the body to ionizing radiation can result in Acute Radiation Sickness (ARS), which can cause symptoms that range from mild to severe, and include death. One of the syndromes that can occur during ARS is the hematopoietic syndrome, which is characterized by a reduction in bone marrow cells as well as the number of circulating blood cells. Doses capable of causing this syndrome can result from conventional radiation therapy and accidental exposure to ionizing radiation. It is of concern that this syndrome could also occur during space exploration class missions in which astronauts could be exposed to significant doses of solar particle event (SPE) radiation. Of particular concern is the reduction of lymphocytes and granulocytes, which are major components of the immune system. A significant reduction in their numbers can compromise the immune system, causing a higher risk for the development of infections which could jeopardize the success of the mission. Although there are no specific countermeasures utilized for the ARS resulting from exposure to space radiation(s), granulocyte colony-stimulating factor (G-CSF) has been proposed as a countermeasure for the low number of neutrophils caused by SPE radiation, but so far no countermeasure exists for a reduced number of circulating lymphocytes. The present study demonstrates that orally administered fructose significantly increases the number of peripheral lymphocytes reduced by exposure of mice to 2 Gy of gamma- or SPE-like proton radiation, making it a potential countermeasure for this biological end-point. PMID:25360417

  18. Orally Administered Fructose Increases the Numbers of Peripheral Lymphocytes Reduced by Exposure of Mice to Gamma or SPE-like Proton Radiation.

    PubMed

    Romero-Weaver, A L; Ni, J; Lin, L; Kennedy, A R

    2014-07-01

    Exposure of the whole body or a major portion of the body to ionizing radiation can result in Acute Radiation Sickness (ARS), which can cause symptoms that range from mild to severe, and include death. One of the syndromes that can occur during ARS is the hematopoietic syndrome, which is characterized by a reduction in bone marrow cells as well as the number of circulating blood cells. Doses capable of causing this syndrome can result from conventional radiation therapy and accidental exposure to ionizing radiation. It is of concern that this syndrome could also occur during space exploration class missions in which astronauts could be exposed to significant doses of solar particle event (SPE) radiation. Of particular concern is the reduction of lymphocytes and granulocytes, which are major components of the immune system. A significant reduction in their numbers can compromise the immune system, causing a higher risk for the development of infections which could jeopardize the success of the mission. Although there are no specific countermeasures utilized for the ARS resulting from exposure to space radiation(s), granulocyte colony-stimulating factor (G-CSF) has been proposed as a countermeasure for the low number of neutrophils caused by SPE radiation, but so far no countermeasure exists for a reduced number of circulating lymphocytes. The present study demonstrates that orally administered fructose significantly increases the number of peripheral lymphocytes reduced by exposure of mice to 2 Gy of gamma- or SPE-like proton radiation, making it a potential countermeasure for this biological end-point. PMID:25360417

  19. Using RADFET for the real-time measurement of gamma radiation dose rate

    NASA Astrophysics Data System (ADS)

    Andjelkovi?, Marko S.; Risti?, Goran S.; Jakši?, Aleksandar B.

    2015-02-01

    RADFETs (RADiation sensitive Field Effect Transistors) are integrating ionizing radiation dosimeters operating on the principle of conversion of radiation-induced threshold voltage shift into absorbed dose. However, one of the major drawbacks of RADFETs is the inability to provide the information on the dose rate in real-time using the conventional absorbed dose measurement technique. The real-time monitoring of dose rate and absorbed dose can be achieved with the current mode dosimeters such as PN and PIN diodes/photodiodes, but these dosimeters have some limitations as absorbed dose meters and hence they are often not a suitable replacement for RADFETs. In that sense, this paper investigates the possibility of using the RADFET as a real-time dose rate meter so that it could be applied for simultaneous online measurement of the dose rate and absorbed dose. A RADFET sample, manufactured by Tyndall National Institute, Cork, Ireland, was tested as a dose rate meter under gamma irradiation from a Co-60 source. The RADFET was configured as a PN junction, such that the drain, gate and source terminals were grounded, while the radiation-induced current was measured at the bulk terminal, whereby the bulk was successively biased with 0?, 10?, 20? and 30?V. In zero-bias mode the radiation-induced current was unstable, but in the biased mode the current response was stable for the investigated dose rates from 0.65? to 32.1?Gy?h?1 and up to the total absorbed dose of 25?Gy. The current increased with the dose rate in accordance with the power law, whereas the sensitivity of the current read-out was linear with respect to the applied bias voltage. Comparison with previously analyzed PIN photodiodes has shown that the investigated RADFET is competitive with PIN photodiodes as a gamma radiation dose rate meter and therefore has the potential to be employed for the real-time monitoring of the dose rate and absorbed dose.

  20. TeV Gamma Rays from BL Lac Objects due to Synchrotron Radiation of Extremely High Energy Protons

    E-print Network

    F. A. Aharonian

    2000-11-18

    One of remarkable features of the gamma ray blazar Markarian 501 is the reported shape of the TeV spectrum, which during strong flares of the source remains essentially stable despite dramatic variations of the absolute gamma-ray flux. I argue that this (to a large extent unexpected) behavior of the source could be explained assuming that the TeV gamma-ray emission is a result of synchrotron radiation of extremely high energy protons in highly magnetized compact regions of the jet.

  1. Estimation of {sup 237}U Level Density and Radiative Strength Functions from the (n-bar,{gamma}) Reaction

    SciTech Connect

    Sukhovoj, Anatoly M.; Khitrov, Valery A. [Joint Institute for Nuclear Research, Dubna, Russia, 141980 (Russian Federation); Maslov, Vladimir M. [Joint Institute for Nuclear and Energy Research, Minsk-Sosny, Belarus, 220109 (Belarus)

    2009-01-28

    Intensity distribution of the primary {gamma}-transitions following resonance neutron capture in {sup 236}U about the mean value was approximated in different energy intervals of these quanta and neutrons. Extrapolation of the obtained functions to zero registration threshold of {gamma}-transitions allowed independent estimation of the expected level number of both parities for spin values J = 1/2, 3/2 and sum of radiative widths for both electric and magnetic gamma-transitions to levels with excitation energy up to {approx_equal}2.3 MeV.

  2. Ionizing radiation, ion transports, and radioresistance of cancer cells

    PubMed Central

    Huber, Stephan M.; Butz, Lena; Stegen, Benjamin; Klumpp, Dominik; Braun, Norbert; Ruth, Peter; Eckert, Franziska

    2013-01-01

    The standard treatment of many tumor entities comprises fractionated radiation therapy which applies ionizing radiation to the tumor-bearing target volume. Ionizing radiation causes double-strand breaks in the DNA backbone that result in cell death if the number of DNA double-strand breaks exceeds the DNA repair capacity of the tumor cell. Ionizing radiation reportedly does not only act on the DNA in the nucleus but also on the plasma membrane. In particular, ionizing radiation-induced modifications of ion channels and transporters have been reported. Importantly, these altered transports seem to contribute to the survival of the irradiated tumor cells. The present review article summarizes our current knowledge on the underlying mechanisms and introduces strategies to radiosensitize tumor cells by targeting plasma membrane ion transports. PMID:23966948

  3. A new analytical formula for neutron capture gamma dose calculations in double-bend mazes in radiation therapy

    PubMed Central

    Ghiasi, Hosein; Mesbahi, Asghar

    2012-01-01

    Background Photoneutrons are produced in radiation therapy with high energy photons. Also, capture gamma rays are the byproduct of neutrons interactions with wall material of radiotherapy rooms. Aim In the current study an analytical formula was proposed for capture gamma dose calculations in double bend mazes in radiation therapy rooms. Materials and methods A total of 40 different layouts with double-bend mazes and a 18 MeV photon beam of Varian 2100 Clinac were simulated using MCNPX Monte Carlo (MC) code. Neutron capture gamma ray dose equivalent was calculated by the MC method along the maze and at the maze entrance door of all the simulated rooms. Then, all MC resulted data were fitted to an empirical formula for capture gamma dose calculations. Wu–McGinley analytical formula for capture gamma dose equivalent at the maze entrance door in single-bend mazes was also used for comparison purposes. Results For capture gamma dose equivalents at the maze entrance door, the difference of 2–11% was seen between MC and the derived equation, while the difference of 36–87% was found between MC and the Wu–McGinley methods. Conclusion Our results showed that the derived formula results were consistent with the MC results for all of 40 different geometries. However, as a new formula, further evaluations are required to validate its use in practical situations. Finally, its application is recommend for capture gamma dose calculations in double-bend mazes to improve shielding calculations. PMID:24377027

  4. Gamma

    NSDL National Science Digital Library

    The Geometric Algorithms for Modeling, Motion, and Animation (GAMMA) research group is part of the Department of Computer Science at the University of North Carolina. Some of the topics of research include haptics, "robot motion planning," collision detection, and "real-time interaction with virtual environments." There are several projects that are described in detail for each of the main areas of investigation. Many recent papers are offered that describe the progress and findings of the group's research. Additionally, there is a large collection of videos demonstrating computer animation, simulation, and interactive applications. Some software can also be downloaded for the GAMMA Web site; however, access to a few of the titles must first be approved by the system administrator.

  5. Evidence for clonal selection of gamma/delta T cells in response to a human pathogen

    PubMed Central

    1991-01-01

    T cells bearing gamma/delta antigen receptors comprise a resident population of intraepithelial lymphocytes in organs such as skin, gut, and lungs, where they are strategically located to contribute to the initial defense against infection. An important unsolved question about antigen-driven gamma/delta T cell responses regards the breadth of their T cell receptor (TCR) repertoire, since many specific epithelial compartments in mice display limited diversity. We have examined the diversity of TCR delta gene expression among human gamma/delta T cells from skin lesions induced by intradermal challenge with Mycobacterium leprae. We show that the vast majority of gamma/delta cells from M. leprae lesions use either V delta 1-J delta 1 or V delta 2-J delta 1 gene rearrangements and, within a given region of the lesion, display limited junctional diversity. This contrasts markedly with the extensive diversity of gamma/delta T cells from peripheral blood of these same individuals, as well as skin from normal donors. These results indicate that the gamma/delta response to M. leprae involves the selection of a limited number of clones from among a diverse repertoire, probably in response to specific mycobacterial and/or host antigens. PMID:1651977

  6. Gamma-interferon alters globin gene expression in neonatal and adult erythroid cells

    SciTech Connect

    Miller, B.A.; Perrine, S.P.; Antognetti, G.; Perlmutter, D.H.; Emerson, S.G.; Sieff, C.; Faller, D.V.

    1987-06-01

    The effect of gamma-interferon on fetal hemoglobin synthesis by purified cord blood, fetal liver, and adult bone marrow erythroid progenitors was studied with a radioligand assay to measure hemoglobin production by BFU-E-derived erythroblasts. Coculture with recombinant gamma-interferon resulted in a significant and dose-dependent decrease in fetal hemoglobin production by neonatal and adult, but not fetal, BFU-E-derived erythroblasts. Accumulation of fetal hemoglobin by cord blood BFU-E-derived erythroblasts decreased up to 38.1% of control cultures (erythropoietin only). Synthesis of both G gamma/A gamma globin was decreased, since the G gamma/A gamma ratio was unchanged. Picograms fetal hemoglobin per cell was decreased by gamma-interferon addition, but picograms total hemoglobin was unchanged, demonstrating that a reciprocal increase in beta-globin production occurred in cultures treated with gamma-interferon. No toxic effect of gamma-interferon on colony growth was noted. The addition of gamma-interferon to cultures resulted in a decrease in the percentage of HbF produced by adult BFU-E-derived cells to 45.6% of control. Fetal hemoglobin production by cord blood, fetal liver, and adult bone marrow erythroid progenitors, was not significantly affected by the addition of recombinant GM-CSF, recombinant interleukin 1 (IL-1), recombinant IL-2, or recombinant alpha-interferon. Although fetal progenitor cells appear unable to alter their fetal hemoglobin program in response to any of the growth factors added here, the interaction of neonatal and adult erythroid progenitors with gamma-interferon results in an altered expression of globin genes.

  7. Limits to the radiative decays of neutrinos and axions from gamma-ray observations of SN 1987A

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Turner, Michael S.

    1989-01-01

    Gamma-ray observations obtained by the SMM gamma-ray spectrometer in the energy range 4.1-6.4 MeV are used to provide limits on the possible radiative decay of neutrinos and axions emitted by SN 1987A. For branching ratio values for the radiative decay modes of less than about 0.0001, the present limits are more stringent than those based upon the photon flux from decaying relic neutrinos. The data are also used to set an axion mass limit.

  8. Determination of radiative neutron capture cross sections for unstable nuclei by the {gamma}-ray strength function method

    SciTech Connect

    Utsunomiya, H.; Goriely, S. [Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501 (Japan); Institut d'Astronomie et d'Astrophysique, Universite Libre de Bruxelles, Campus de la Plaine, CP-226, 1050 Brussels (Belgium)

    2012-11-12

    An indirect method referred to as the {gamma}-ray strength function method has been devised to determine radiative neutron capture cross sections for unstable nuclei along the valley of {beta}-stability. This method is based on the {gamma}-ray strength function which interconnects radiative neutron capture and photoneutron emission within the statistical model. The method was applied to several unstable nuclei such as {sup 93,95}Zr, {sup 107}Pd, and 121,123Sn. This method offers a versatile application extended to unstable nuclei far from the stability when combined with Coulomb dissociation experiments at RIKEN-RIBF and GSI.

  9. Enhanced annealing of GaAs solar cell radiation damage

    NASA Technical Reports Server (NTRS)

    Loo, R.; Knechtli, R. C.; Kamath, G. S.

    1981-01-01

    Solar cells are degraded by radiation damage in space. Investigations have been conducted concerning possibilities for annealing this radiation damage in GaAs solar cells, taking into account the conditions favoring such annealing. It has been found that continuous annealing as well as the combination of injection annealing with thermal annealing can lead to recovery from radiation damage under particularly favorable conditions in GaAs solar cells. The damage caused by both electrons and protons in GaAs solar cells can be substantially reduced by annealing at temperatures as low as 150 C, under appropriate conditions. This possibility makes the GaAs solar cells especially attractive for long space missions, or for missions in severe radiation environments. Attention is given to results concerning periodic thermal annealing, continuous annealing, and injection annealing combined with thermal annealing.

  10. Survival and self-renewing capacity of breast cancer initiating cells during fractionated radiation treatment

    E-print Network

    2010-01-01

    cancer initiating cells during fractionated radiation treatment.cancer initiating cells during fractionated radiation treatmentradiation resistant CICs in breast cancer are not only viable after treatment

  11. Measurement of Branching Fractions in Radiative BDecays to eta K gamma and Search for B Decays to eta' K gamma

    SciTech Connect

    Aubert, B.

    2006-03-31

    The authors present measurements of the B {yields} {eta}K{gamma} branching fractions and upper limits for the B {yields} {eta}'K{gamma} branching fractions. For B{sup +} {yields} {eta}K{sup +}{gamma} they also measure the time-integrated charge asymmetry. The data sample, collected with the BABAR detector at the Stanford Linear Accelerator Center, represents 232 x 10{sup 6} produced B{bar B} pairs. The results for branching fractions and upper limits at 90% C.L. in units of 10{sup -6} are: {Beta}(B{sup 0} {yields} {eta}K{sup 0}{gamma}) = 11.3{sub -2.6}{sup +2.8} {+-} 0.6, {Beta}(B{sup +} {yields} {eta}K{sup +}{gamma}) = 10.0 {+-} 1.3 {+-} 0.5, {Beta}(B{sup 0} {yields} {eta}'K{sup 0}{gamma}) < 6.6, {Beta}(B{sup +} {yields} {eta}'K{sup +}{gamma}) < 4.2. The charge asymmetry in the decay B{sup +} {yields} {eta}K{sup +}{gamma} is {Alpha}{sub ch} = -0.09 {+-} 0.12 {+-} 0.01. The first errors are statistical and the second systematic.

  12. Application of adipocyte-derived stem cells in treatment of cutaneous radiation syndrome.

    PubMed

    Riccobono, Diane; Agay, Diane; Scherthan, Harry; Forcheron, Fabien; Vivier, Mylène; Ballester, Bruno; Meineke, Viktor; Drouet, Michel

    2012-08-01

    Cutaneous radiation syndrome caused by local high dose irradiation is characterized by delayed outcome and incomplete healing. Recent therapeutic management of accidentally irradiated burn patients has suggested the benefit of local cellular therapy using mesenchymal stem cell grafting. According to the proposed strategy of early treatment, large amounts of stem cells would be necessary in the days following exposure and hospitalization, which would require allogeneic stem cells banking. In this context, the authors compared the benefit of local autologous and allogeneic adipocyte-derived stem cell injection in a large animal model. Minipigs were locally irradiated using a 60Co gamma source at a dose of 50 Gy and divided into three groups. Two groups were grafted with autologous (n = 5) or allogeneic (n = 5) adipocyte-derived stem cells four times after the radiation exposure, whereas the control group received the vehicle without cells (n = 8). A clinical score was elaborated to compare the efficiency of the three treatments. All controls exhibited local inflammatory injuries leading to a persistent painful necrosis, thus mimicking the clinical evolution in human victims. In the autologous adipocyte-derived stem cells group, skin healing without necrosis or uncontrollable pain was observed. In contrast, the clinical outcome was not significantly different in the adipocyte-derived stem cell allogeneic group when compared with controls. This study suggests that autologous adipocyte-derived stem cell grafting improves cutaneous radiation syndrome wound healing, whereas allogeneic adipocyte derived stem cells do not. Further studies will establish whether manipulation of allogeneic stem cells will improve their therapeutic potential. PMID:22951469

  13. Investigation of Radiation Hardness of Germanium Photovoltaic Cells

    Microsoft Academic Search

    Raymond Hoheisel; Jara Fernandez; Frank Dimroth; Andreas W. Bett

    2010-01-01

    This contribution discusses the radiation hardness of germanium (Ge) photovoltaic cells under space conditions corresponding to an irradiation dose of 1-MeV 1 × 1015 cm-2 electrons. For this purpose, different germanium photovoltaic cell technologies based on p-type substrates are analyzed. The investigation comprises standard Ge photovoltaic cells with a substrate doping concentration of NA = 1 × 1017 cm-3, as

  14. Space Radiation Effects in Advanced Solar Cell Materials and Devices

    Microsoft Academic Search

    R. J. Walters; G. P. Summers

    An investigation of the physical mechanisms governing the response of III-V based solar cells to particle irradiation is presented. The effect of particle irradiation on single and multijunction solar cells is studied through current vs. voltage, spectral response, and deep level transient spectroscopy measurements. The basic radiation response mechanisms are identified, and their effects on the solar cell electrical performance

  15. Interferon-gamma-producing T cells in giant cell vasculitis represent a minority of tissue-infiltrating cells and are located distant from the site of pathology.

    PubMed Central

    Wagner, A. D.; Björnsson, J.; Bartley, G. B.; Goronzy, J. J.; Weyand, C. M.

    1996-01-01

    Giant cell vasculitis is an arteritis that predominantly affects medium- and large-sized arteries. Genetic risk factors and clonal expansion of selected CD4+ T cell specificities in the vascular lesions support the model that giant cell arteritis is a T-cell-driven disease. Interferon (IFN)-gamma production in the tissue is intimately associated with the formation of the inflammatory infiltrates. Antigens inducing stimulation of T cells are unknown. To provide indirect evidence for the type and the tissue localization of the antigen, we examined CD4+ T cells in the lesions that secrete IFN-gamma. Temporal artery specimens from patients with giant cell arteritis were analyzed bu two-color immunohistochemistry applying antibodies to T cell markers. IFN-gamma, the interleukin-2 receptor alpha-chain (CD25) and talin, a cytoskeletal protein that is reorganized in T cells interacting with antigen-presenting cells. Proliferating cells in the lesions were identified through the expression of the Ki-67 nuclear antigen. More than 90% of tissue-infiltrating IFN-gamma-producing cells were CD4+ CD45RO+. They represented a minute subset (2 to 4%) of tissue-infiltrating T cells. IFN-gamma+ T cells aggregated in the adventitial layer of the inflamed artery where they were either diffusely distributed or arranged in clusters. The majority of IFN-gamma-secreting T cells expressed CD25. IFN-gamma+ T cells included a fraction of cells that had reorganized the cytoskeletal protein talin, indicating an interaction of the T cell receptor and an antigen-presenting cell. A subset of IFN-gamma-expressing T cells was undergoing proliferation in the tissue. IFN-gamma-producing T cells in vasculitic lesions of giant cell arteritis express several markers that identify them as T cells that have recently been stimulated through their antigen-specific receptor. These putatively disease-relevant T cells represent only a very minor fraction of tissue-infiltrating cells. Their preferential accumulation in the adventitia is most compatible with the model that they contact the relevant antigen primarily in this particular region of the artery. Their regulatory function appears to extend into the inner media and intima where pathological changes in giant cell arteritis are most pronounced. Images Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 PMID:8669478

  16. DNA repair and radiation sensitivity in mammalian cells

    SciTech Connect

    Chen, D.J.C.; Stackhouse, M. (Los Alamos National Lab., NM (United States)); Chen, D.S. (Rochester Univ., NY (United States). Dept. of Radiation Oncology)

    1993-01-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  17. DNA repair and radiation sensitivity in mammalian cells

    SciTech Connect

    Chen, D.J.C.; Stackhouse, M. [Los Alamos National Lab., NM (United States); Chen, D.S. [Rochester Univ., NY (United States). Dept. of Radiation Oncology

    1993-02-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  18. Induction of ceruloplasmin synthesis by IFN-gamma in human monocytic cells

    NASA Technical Reports Server (NTRS)

    Mazumder, B.; Mukhopadhyay, C. K.; Prok, A.; Cathcart, M. K.; Fox, P. L.

    1997-01-01

    Ceruloplasmin is a 132-kDa glycoprotein abundant in human plasma. It has multiple in vitro activities, including copper transport, lipid pro- and antioxidant activity, and oxidation of ferrous ion and aromatic amines; however, its physiologic role is uncertain. Although ceruloplasmin is synthesized primarily by the liver in adult humans, production by cells of monocytic origin has been reported. We here show that IFN-gamma is a potent inducer of ceruloplasmin synthesis by monocytic cells. Activation of human monoblastic leukemia U937 cells with IFN-gamma increased the production of ceruloplasmin by at least 20-fold. The identity of the protein was confirmed by plasmin fingerprinting. IFN-gamma also increased ceruloplasmin mRNA. Induction followed a 2- to 4-h lag and was partially blocked by cycloheximide, indicating a requirement for newly synthesized factors. Ceruloplasmin induction in monocytic cells was agonist specific, as IL-1, IL-4, IL-6, IFN-alpha, IFN-beta, TNF-alpha, and LPS were completely ineffective. The induction was also cell type specific, as IFN-gamma did not induce ceruloplasmin synthesis in endothelial or smooth muscle cells. In contrast, IFN-gamma was stimulatory in other monocytic cells, including THP-1 cells and human peripheral blood monocytes, and also in HepG2 cells. Ceruloplasmin secreted by IFN-gamma-stimulated U937 cells had ferroxidase activity and was, in fact, the only secreted protein with this activity. Monocytic cell-derived ceruloplasmin may contribute to defense responses via its ferroxidase activity, which may drive iron homeostasis in a direction unfavorable to invasive organisms.

  19. Measurement of $K^- p$ radiative capture to $\\gamma \\Lambda$ and $\\gamma \\Sigma^0$ for $p_{K^-}$ between 514 and 750 MeV/$c$

    E-print Network

    Prakhov, S; Phaisangittisakul, N; Nefkens, B M K; Allgower, C E; Bekrenev, V; Briscoe, W J; De Cruz, L; Isenhower, D; Knecht, N; Koulbardis, A; Kozlenko, N; Kruglov, S; Lolos, G; Lopatin, I; Manley, D M; Maruši?, A; McDonald, S; Olmsted, J; Papandreou, Z; Peaslee, D; Price, J W; Ryckebusch, J; Sadler, M; Shafi, A; Starostin, A; Staudenmaier, H M; Strakovsky, I I; Supek, I; Van Cauteren, T

    2009-01-01

    Differential cross sections for $K^-$ radiative capture in flight on the proton, leading to the $\\gamma\\Lambda$ and $\\gamma\\Sigma^0$ final states, have been measured at eight $K^-$ momenta between 514 and 750 MeV/$c$. The data were obtained with the Crystal Ball multiphoton spectrometer installed at the separated $K/\\pi$ beam line C6 of the BNL Alternating Gradient Synchrotron. The results substantially improve the existing experimental data available for studying radiative decays of excited hyperon states. An exploratory theoretical analysis is performed within the Regge-plus-resonance approach. According to this analysis, the $\\gamma\\Sigma^0$ final state is dominated by hyperonresonance exchange and hints at an important role for a resonance in the mass region of 1700 MeV. In the $\\gamma\\Lambda$ final state, on the other hand, the resonant contributions account for only half the strength, and the data suggest the importance of a resonance in the mass region of 1550 MeV.

  20. Annihilation radiation from a hot e/+/-e/-/ plasma. [gamma ray bursts

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Meszaros, P.

    1981-01-01

    The radiation from electron-positron annihilations in a plasma of temperature above 10 to the 8th K is investigated as a possible source of the emission line at energies between 400 and 460 keV frequently seen in gamma-ray bursts. The annihilation rate and luminosity of an optically thin electron-positron plasma and the energy distribution of the resulting annihilation radiation are calculated by the use of a Monte Carlo technique as functions of temperature. Results indicate the annihilation spectrum to be peaked at an energy of 0.511 MeV plus a temperature-dependent blueshift, and the annihilation line to be significantly temperature-broadened. The widths of the observed burst emission lines set an upper limit of 3 x 10 to the 8th K on the temperature of any pair annihilation region in burst sources, which is considerably lower than the typical kinetic temperatures of the radiating particles. It is thus inferred that either the annihilation region is nonthermal, or spatially distinct from the burst site.

  1. Mortality of the harvester ant (Pogonomyrmex owyheei) after exposure to /sup 137/Cs gamma radiation

    SciTech Connect

    Gano, K.A.

    1981-01-01

    Harvester ants, Pogonomyrmex owyheei Cole, irradiated with 3.5 kR to 268 kR of /sup 137/Cs gamma radiation, were maintained at simulated summer (27/sup 0/C) and winter (7/sup 0/C) temperature regimes. After thirty days, the cool series was warmed to 27/sup 0/C and observed for mortality along with the warm series. Though mortality was delayed in the cool series, each series reached 50% mortality at similar rates. Because the harvester ant is extremely tolerant to radiation and experimental rates used far exceed possible environmental exposure, it is unlikely that ant colonies dwelling among low-level nuclear waste storage sites will be deleteriously affected by radiation. This species has the capability of tunneling to a depth well within the range of some buried waste. Since these harvester ants are potential transporters of buried waste, they should be considered as a biotic factor in radioactive waste management operations in semi-arid regions.

  2. Mortality of the harvester ant (Pogonomyrmex owyheei) after exposure to /sup 137/Cs gamma radiation

    SciTech Connect

    Gano, K.A.

    1981-01-01

    Harvester ants, Pogonomyrmex owyheei Cole, irradiated with 3.5 kR to 268 kR of /sup 137/Cs gamma radiation, were maintained at simulated summer (27/sup 0/C) and winter (7/sup 0/C) temperature regimes. After thirty days, the cool series was warmed to 27/sup 0/C and observed for mortality along with the warm series.Though mortality was delayed in the cool series, each series reached 50% mortality at similar rates. Because the harvester ant is extremely tolerant to radiation and experimental rates used far exceed possible environmental exposure, it is unlikely that ant colonies dwelling among low-level nuclear waste storage sites will be deleteriously affected by radiation. This species has the capability of tunneling to a depth well within the range of some buried waste. Since these harvester ants are potential transporters of buried waste, they should be considered as a biotic factor in radioactive waste management operations in semi-arid regions.

  3. Cell-cycle radiation response: role of intracellular factors.

    PubMed

    Blakely, E; Chang, P; Lommel, L; Bjornstad, K; Dixon, M; Tobias, C; Kumar, K; Blakely, W F

    1989-01-01

    We have been studying variations of radiosensitivity and endogenous cellular factors during the course of progression through the human and hamster cell cycle. After exposure to low-LET radiations, the most radiosensitive cell stages are mitosis and the G1/S interface. The increased activity of a specific antioxidant enzyme such as superoxide dismutase in G1-phase, and the variations of endogenous thiols during cell division are thought to be intracellular factors of importance to the radiation survival response. These factors may contribute to modifying the age-dependent yield of lesions or more likely, to the efficiency of the repair processes. These molecular factors have been implicated in our cellular measurements of the larger values for the radiobiological oxygen effect late in the cycle compared to earlier cell ages. Low-LET radiation also delays progression through S phase which may allow more time for repair and hence contribute to radioresistance in late-S-phase. The cytoplasmic and intranuclear milieu of the cell appears to have less significant effects on lesions produced by high-LET radiation compared to those made by low-LET radiation. High-LET radiation fails to slow progression through S phase, and there is much less repair of lesions evident at all cell ages; however, high-LET particles cause a more profound block in G2 phase than that observed after low-LET radiation. Hazards posed by the interaction of damage from sequential doses of radiations of different qualities have been evaluated and are shown to lead to a cell-cycle-dependent enhancement of radiobiological effects. A summary comparison of various cell-cycle-dependent endpoints measured with low- or high-LET radiations is given and includes a discussion of the possible additional effects introduced by microgravity. PMID:11537290

  4. Age-related changes in T gamma delta cells of NOD mice.

    PubMed

    Funda, D; Stenvang, J P; Buschard, K

    1995-03-01

    T gamma delta cells have been reported to recognize both mycobacterial and human heat-shock proteins (HSP), and a possible role of 65 kDa HSP has been suggested also in the pathogenesis of insulin-dependent diabetes mellitus. The aim of this study was to investigate age-related changes of T gamma delta cells during diabetes development in non-obese diabetic (NOD) mice. Using FACS analysis relative numbers of T gamma delta + cells from thymus, blood and spleen were determined in a 3-week-old non-diabetic, at onset of diabetes, and 1-week diabetic NOD mice and corresponding BALB/cJ controls. In comparison to BALB/cJ mice, higher values (2.4 +/- 0.2% vs. 1.1 +/- 0.1%) were found in the thymus of 3-week-old NOD mice (P < 0.01) as well as spleens of 22-week-old littermates (1.1 +/- 0.1% vs. 0.6 +/- 0.1%, P < 0.01). In addition, a higher proportion of T gamma delta cells was observed in blood samples of all age groups of NOD as compared to BALB/cJ mice, with values 3.5 +/- 0.7% (P < 0.05) in 3-week-old to 4.4 +/- 0.9% and 3.7 +/- 0.3% (P < 0.01) in 16- and 22-week-old NOD littermates. Differences in TCR gamma delta expression did not influence the whole CD3+ subset of mononuclear cells. Thus, our results show relatively higher numbers of T gamma delta cells in NOD mice and their increase in the periphery at onset of diabetes and later may suggest that T gamma delta cells participate in beta-cell destruction. PMID:7558171

  5. mBAND analysis of chromosome aberrations in human epithelial cells induced by gamma-rays and secondary neutrons of low dose rate.

    PubMed

    Hada, M; Gersey, B; Saganti, P B; Wilkins, R; Cucinotta, F A; Wu, H

    2010-08-14

    Human risks from chronic exposures to both low- and high-LET radiation are of intensive research interest in recent years. In the present study, human epithelial cells were exposed in vitro to gamma-rays at a dose rate of 17 mGy/h or secondary neutrons of 25 mGy/h. The secondary neutrons have a broad energy spectrum that simulates the Earth's atmosphere at high altitude, as well as the environment inside spacecrafts like the Russian MIR station and the International Space Station (ISS). Chromosome aberrations in the exposed cells were analyzed using the multicolor banding in situ hybridization (mBAND) technique with chromosome 3 painted in 23 colored bands that allows identification of both inter- and intrachromosome exchanges including inversions. Comparison of present dose responses between gamma-rays and neutron irradiations for the fraction of cells with damaged chromosome 3 yielded a relative biological effectiveness (RBE) value of 26+/-4 for the secondary neutrons. Our results also revealed that secondary neutrons of low dose rate induced a higher fraction of intrachromosome exchanges than gamma-rays, but the fractions of inversions observed between these two radiation types were indistinguishable. Similar to the previous findings after acute radiation exposures, most of the inversions observed in the present study were accompanied by other aberrations. The fractions of complex type aberrations and of unrejoined chromosomal breakages were also found to be higher in the neutron-exposed cells than after gamma-rays. We further analyzed the location of the breaks involved in chromosome aberrations along chromosome 3, and observed hot spots after gamma-ray, but not neutron, exposures. PMID:20338263

  6. Radiation-induced transmissable chromosomal instability in haemopoietic stem cells

    NASA Astrophysics Data System (ADS)

    Kadhim, M. A.; Wright, E. G.

    Heritable radiation-induced genetic alterations have long been assumed to be ``fixed'' within the first cell division. However, there is a growing body of evidence that a considerable fraction of cells surviving radiation exposure appear normal, but a variety of mutational changes arise in their progeny due to a transmissible genomic instability. In our investigations of G-banded metaphases, non-clonal cytogenetic aberrations, predominantly chromatid-type aberrations, have been observed in the clonal descendants of murine and human haemopoietic stem cells surviving low doses (~1 track per cell) of alpha-particle irradiations. The data are consistent with a transmissible genetic instability induced in a stem cell resulting in a diversity of chromosomal aberrations in its clonal progeny many cell divisions later. Recent studies have demonstrated that the instability phenotype persists in vivo and that the expression of chromosomal instability has a strong dependence on the genetic characteristics of the irradiated cell. At the time when cytogenetic aberrations are detected, an increased incidence of hprt mutations and apoptotic cells have been observed in the clonal descendants of alpha-irradiated murine haemopoietic stem cells. Thus, delayed chromosomal abnormalities, delayed cell death by apoptosis and late-arising specific gene mutations may reflect diverse consequences of radiation-induced genomic instability. The relationship, if any, between these effects is not established. Current studies suggest that expression of these delayed heritable effects is determined by the type of radiation exposure, type of cell and a variety of genetic factors.

  7. Effect of Gamma Radiation on Optical and EPR Absorption Spectra of Phosphate and Fluoride Glasses Containing Lead

    Microsoft Academic Search

    T. V. Bocharova; G. O. Karapetyan

    2005-01-01

    The induced optical and EPR absorption spectra of phosphate and fluoride glasses containing lead are investigated. It is revealed\\u000a that exposure to gamma radiation leads to the formation of radiation-induced defects responsible for the induced absorption\\u000a band with a maximum at 12500–13500 cm?1 and the EPR signal in the form of an almost symmetric line with a g factor of

  8. Activation of peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}) induces cell death through MAPK-dependent mechanism in osteoblastic cells

    SciTech Connect

    Kim, Sung Hun [Department of Orthopedic Surgery, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of); Yoo, Chong Il [Department of Orthopedic Surgery, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of); Medical Research Institute, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of); Kim, Hui Taek [Department of Orthopedic Surgery, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of); Medical Research Institute, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of); Park, Ji Yeon [Department of Physiology, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of); Kwon, Chae Hwa [Department of Physiology, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of); Keun Kim, Yong [Department of Physiology, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of) and Medical Research Institute, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of) and MRC for Ischemic Tissue Regeneration, College of Medicine, Pusan National University, Pusan, 602-739 (Korea, Republic of)]. E-mail: kim430@pusan.ac.kr

    2006-09-01

    The present study was undertaken to determine the role of the mitogen-activated protein kinase (MAPK) subfamilies in cell death induced by PPAR{gamma} agonists in osteoblastic cells. Ciglitazone and troglitazone, PPAR{gamma} agonists, resulted in a concentration- and time-dependent cell death, which was largely attributed to apoptosis. But a PPAR{alpha} agonist ciprofibrate did not affect the cell death. Ciglitazone caused reactive oxygen species (ROS) generation and ciglitazone-induced cell death was prevented by antioxidants, suggesting an important role of ROS generation in the ciglitazone-induced cell death. ROS generation and cell death induced by ciglitazone were inhibited by the PPAR{gamma} antagonist GW9662. Ciglitazone treatment caused activation of extracellular signal-regulated kinase (ERK) and p38. Activation of ERK was dependent on epidermal growth factor receptor (EGFR) and that of p38 was independent. Ciglitazone-induced cell death was significantly prevented by PD98059, an inhibitor of ERK upstream kinase MEK1/2, and SB203580, a p38 inhibitor. Ciglitazone treatment increased Bax expression and caused a loss of mitochondrial membrane potential, and its effect was prevented by N-acetylcysteine, PD98059, and SB203580. Ciglitazone induced caspase activation, which was prevented by PD98059 and SB203580. The general caspase inhibitor z-DEVD-FMK and the specific inhibitor of caspases-3 DEVD-CHO exerted the protective effect against the ciglitazone-induced cell death. The EGFR inhibitors AG1478 and suramin protected against the ciglitazone-induced cell death. Taken together, these findings suggest that the MAPK signaling pathways play an active role in mediating the ciglitazone-induced cell death of osteoblasts and function upstream of a mitochondria-dependent mechanism. These data may provide a novel insight into potential therapeutic strategies for treatment of osteoporosis.

  9. The role of meiotic cohesin REC8 in chromosome segregation in {gamma} irradiation-induced endopolyploid tumour cells

    SciTech Connect

    Erenpreisa, Jekaterina [Latvian Biomedicine Research and Study Centre, Riga, LV-1067 (Latvia)] [Latvian Biomedicine Research and Study Centre, Riga, LV-1067 (Latvia); Cragg, Mark S. [Tenovus Laboratory, Cancer Sciences Division, Southampton University School of Medicine, General Hospital, Southampton SO16 6YD (United Kingdom)] [Tenovus Laboratory, Cancer Sciences Division, Southampton University School of Medicine, General Hospital, Southampton SO16 6YD (United Kingdom); Salmina, Kristine [Latvian Biomedicine Research and Study Centre, Riga, LV-1067 (Latvia)] [Latvian Biomedicine Research and Study Centre, Riga, LV-1067 (Latvia); Hausmann, Michael [Kirchhoff Inst. fuer Physik, Univ. of Heidelberg, D-69120 Heidelberg (Germany)] [Kirchhoff Inst. fuer Physik, Univ. of Heidelberg, D-69120 Heidelberg (Germany); Scherthan, Harry, E-mail: scherth@web.de [Inst. fuer Radiobiologie der Bundeswehr in Verbindung mit der Univ. Ulm, D-80937 Munich (Germany) [Inst. fuer Radiobiologie der Bundeswehr in Verbindung mit der Univ. Ulm, D-80937 Munich (Germany); MPI for Molec. Genetics, 14195 Berlin (Germany)

    2009-09-10

    Escape from mitotic catastrophe and generation of endopolyploid tumour cells (ETCs) represents a potential survival strategy of tumour cells in response to genotoxic treatments. ETCs that resume the mitotic cell cycle have reduced ploidy and are often resistant to these treatments. In search for a mechanism for genome reduction, we previously observed that ETCs express meiotic proteins among which REC8 (a meiotic cohesin component) is of particular interest, since it favours reductional cell division in meiosis. In the present investigation, we induced endopolyploidy in p53-dysfunctional human tumour cell lines (Namalwa, WI-L2-NS, HeLa) by gamma irradiation, and analysed the sub-cellular localisation of REC8 in the resulting ETCs. We observed by RT-PCR and Western blot that REC8 is constitutively expressed in these tumour cells, along with SGOL1 and SGOL2, and that REC8 becomes modified after irradiation. REC8 localised to paired sister centromeres in ETCs, the former co-segregating to opposite poles. Furthermore, REC8 localised to the centrosome of interphase ETCs and to the astral poles in anaphase cells where it colocalised with the microtubule-associated protein NuMA. Altogether, our observations indicate that radiation-induced ETCs express features of meiotic cell divisions and that these may facilitate chromosome segregation and genome reduction.

  10. Open cell conducting foams for high synchrotron radiation accelerators

    NASA Astrophysics Data System (ADS)

    Petracca, S.; Stabile, A.

    2014-08-01

    The possible use of open cell conductive foams in high synchrotron radiation particle accelerators is considered. Available materials and modeling tools are reviewed, potential pros and cons are discussed, and preliminary conclusions are drawn.

  11. Natural radioactivity and external gamma radiation exposure at the coastal Red Sea in Egypt.

    PubMed

    Harb, S

    2008-01-01

    Radionuclides which present in different beach sands are sources of external exposure that contribute to the total radiation exposure of human. In this work, superficial samples of beach sand were collected from the Red Sea coastline (Ras Gharib, Hurghada, Safaga, Qusier and Marsa Alam areas) and at 20 km on Qena-Safaga road. The distribution of natural radionuclides in sand beach samples was studied by gamma spectrometry. The activity concentrations of primordial and artificial radionuclides in samples that are collected from the coastal environment of the Red Sea were 19.2 +/- 3 Bq kg(-1) for (210)Pb, 21.1 +/- 1 Bq kg(-1) for (226)Ra, 22.7 +/- 2 Bq kg(-1) for (238)U, 1.0 +/- 0.1 Bq kg(-1) for (235)U, 11.6 +/- 1 Bq kg(-1) for (228)Ra, 13.0 +/- 1 Bq kg(-1) for (228)Th, 12.4 +/- 1 Bq kg(-1) for (232)Th, 930 +/- 32 Bq kg(-1) for (40)K and 1.2 +/- 0.3 Bq kg(-1) for (137)Cs. The mean external gamma-dose rate was 62.5 +/- 3.2 nSv h(-1), 54.4 +/- 2.8 nGy h(-1) Ra equivalent activity (Ra(eq)) was 107 +/- 5.8 Bq kg(-1), 0.86 +/- 0.04 Bq kg(-1) for representative level index (I(gamma)) and effective dose rate was 0.067 +/- 0.003 mSv y(-1) in beach sand red sea, in air due to naturally occurring radionuclides. PMID:18337293

  12. Influence of gamma radiation on the physicochemical and rheological properties of sterculia gum polysaccharides

    NASA Astrophysics Data System (ADS)

    Singh, Baljit; Sharma, Vikrant

    2013-11-01

    Keeping in view the influence of gamma radiation on the physiochemical properties of the polysaccharides and their importance in the food and pharmaceutical industry, in the present study attempt has been made to investigate the effects of absorbed dose on FTIR, XRD, SEMs, absorbance, pH, solubility, water absorption capacity, emulsion stability and rheology of sterculia gum. Increase in solubility and decrease in swellability of gum has been observed on increasing the absorbed dose. The emulsion stability has improved for the gum sample irradiated with total dose of 8.1±0.2 kGy. Apparent viscosity of gum solution first increased with increase in dose from 0 to 8.1±0.2 kGy than decreased with regular trends with further increase in total absorbed dose. Flow behavior of gum solution shifted to Newtonian from non-Newtonian with increasing the dose.

  13. The high energy gamma-ray background and the interstellar radiation field

    NASA Astrophysics Data System (ADS)

    Chary, Ranga-Ram

    This thesis provides an independent estimate of the high latitude (! b! > 20°) contribution to the E > 30 MeV gamma-ray background from Galactic nucleon-nucleon, electron bremsstrahlung and inverse Compton processes. In particular, the inverse Compton contribution has been estimated for different cosmic ray electron distributions and after factoring in the anisotropy in the interstellar radiation field and the anisotropic Klein-Nishina scattering cross section. A model for the interstellar radiation field from 0.1 ?m to 1000 ?m is also presented to fit the intensities observed by recent satellite experiments, especially the DIRBE and FIRAS instruments on COBE. I find that the emission from the inverse Compton process when the anisotropy in the radiation field is included can be higher by up to 50% when compared to estimates that adopt an isotropic radiation field. Simulated inverse Compton maps with a cosmic ray electron distribution represented by a ``pill box'' extending up to a distance of 5 kpc above the Galactic plane provide better fits to the EGRET intensity maps suggesting that the cosmic ray halo may be larger than previously thought. With this distribution, I find that the net contribution from the IC process to the gamma-ray background can be as high as 20% at high Galactic latitudes. Fitting for the Galactic components of gamma-ray emission confirms the existence of an isotropic component with an intensity that can be represented by the form 27.7 × E(MeV)-2.16 photons m-2 s-1 sr -1 MeV-1, in excellent agreement with previous estimates. The spectrum of the isotropic component further argues strongly in favor of unresolved gamma-ray blazars being the source of this emission. Introduction of an anisotropic component improves the quality of the fits. However, this component, which could potentially arise from the dark matter in the Galactic halo, is not well characterized by a single power law which might be associated with any single dark matter candidate. It has an intensity of about a third of the isotropic background above E > 100 MeV-1, at the level of 3 × 10-2 photons m-2 s-1 sr-1 . The best fit power law spectrum to this component has a photon index of -1.7. Based on the intensity and spectrum of the anisotropic component I derive upper limits of 109Msolar for the mass of cold, baryonic gas within the solar circle and a primordial black hole number density limit of 7 × 107 pc -3 which is more than an order of magnitude smaller than previous limits. If the spectrum of the anisotropic component is indeed confirmed to have an index of -1.7, it appears more likely that the signal arises in unresolved Galactic sources such as pulsars.

  14. Finger injury from over-exposure to an industrial gamma radiation source.

    PubMed

    Sahin, Cihan; Cesur, Ceyhun; Sever, Celalettin; Eren, Fikret

    2015-03-01

    The aim of this paper was to report a rare cause of radionecrosis and its long-term results. Iridium-192 ((192)Ir) is commonly used for radiography as a gamma ray source to locate flaws in welds and metal components in gas and oil industry. A 38-year-old man was subjected to radiation unintentionally. One month after the exposure wounds were appeared on the second and third fingers, and they were treated by conventional wound care and hyperbaric oxygen therapy. However wounds were relapsed one year later that brought the patient to us. The wounds were treated by wound care and hyperbaric oxygen therapy. When the patient was brought to us one year later the result was interesting. The third finger's pulp (there was not any wound one year before) was contracted and one third of the distal phalanx was exposed. PMID:25249387

  15. Effects of increased shielding on gamma-radiation levels within spacecraft

    NASA Astrophysics Data System (ADS)

    Haskins, P. S.; McKisson, J. E.; Weisenberger, A. G.; Ely, D. W.; Ballard, T. A.; Dyer, C. S.; Truscott, P. R.; Piercey, R. B.; Ramayya, A. V.; Camp, D. C.

    The Shuttle Activation Monitor (SAM) experiment was flown on the Space Shuttle Columbia (STS-28) from 8 - 13 August, 1989 in a 57°, 300 km orbit. One objective of the SAM experiment was to determine the relative effect of different amounts of shielding on the gamma-ray backgrounds measured with similarly configured sodium iodide (NaI) and bismuth germante (BGO) detectors. To achieve this objective twenty-four hours of data were taken with each detector in the middeck of the Shuttle on the ceiling of the airlock (a high-shielding location) as well as on the sleep station wall (a low-shielding location). For the cosmic-ray induced background the results indicate an increased overall count rate in the 0.2 to 10 MeV energy range at the more highly shielded location, while in regions of trapped radiation the low shielding configuration gives higher rates at the low energy end of the spectrum.

  16. Effect of gamma — radiation on vicine and convicine in broad beans ( Vicia faba L. )

    NASA Astrophysics Data System (ADS)

    Jaddou, H.

    Broad bean ( Vicia faba L. ) is considered to be a good source of protein. The presence of vicine and convicine and their role as a causative agents of favism limited their use. The effect of gamma radiation from 60Co source was tested on solutions of a mixture of vicine and convicine. Analysis was carried out using spectrophotometric method. Reduction of 92% in vicine and convicine was observed when a dose of 10.0 kGy was used. The reduction was very much lower when powdered dry beans was irradiated. Research in progress in order to attain a higher destructive effect. Further chemical and biological studies are also required to follow up this effect.

  17. Novel synthetic (S,S) and (R,R)-secoisolariciresinol diglucosides (SDGs) protect naked plasmid and genomic DNA From gamma radiation damage.

    PubMed

    Mishra, Om P; Pietrofesa, Ralph; Christofidou-Solomidou, Melpo

    2014-07-01

    Secoisolariciresinol diglucoside (SDG) is the major lignan in wholegrain flaxseed. However, extraction methods are complex and are associated with low yield and high costs. Using a novel synthetic pathway, our group succeeded in chemically synthesizing SDG (S,S and R,R enantiomers), which faithfully recapitulates the properties of their natural counterparts, possessing strong antioxidant and free radical scavenging properties. This study further extends initial findings by now investigating the DNA-radioprotective properties of the synthetic SDG enantiomers compared to the commercial SDG. DNA radioprotection was assessed by cell-free systems such as: (a) plasmid relaxation assay to determine the extent of the supercoiled (SC) converted to open-circular (OC) plasmid DNA (pBR322) after exposure of the plasmid to gamma radiation; and (b) determining the extent of genomic DNA fragmentation. Exposure of plasmid DNA to 25 Gy of ? radiation resulted in decreased supercoiled form and increased open-circular form, indicating radiation-induced DNA damage. Synthetic SDG (S,S) and SDG (R,R), and commercial SDG at concentrations of 25-250 ?M significantly and equipotently reduced the radiation-induced supercoiled to open-circular plasmid DNA in a dose-dependent conversion. In addition, exposure of calf thymus DNA to 50 Gy of gamma radiation resulted in DNA fragments of low-molecular weight (<6,000 bps), which was prevented in a dose-dependence manner by all synthetic and natural SDG enantomers, at concentrations as low as 0.5 ?M. These novel results demonstrated that synthetic SDG (S,S) and SDG (R,R) isomers and commercial SDG possess DNA-radioprotective properties. Such properties along with their antioxidant and free radical scavenging activity, reported earlier, suggest that SDGs are promising candidates for radioprotection for normal tissue damage as a result of accidental exposure during radiation therapy for cancer treatment. PMID:24945894

  18. Novel Synthetic (S,S) and (R,R)-Secoisolariciresinol Diglucosides (SDGs) Protect Naked Plasmid and Genomic DNA From Gamma Radiation Damage

    PubMed Central

    Mishra, Om P.; Pietrofesa, Ralph; Christofidou-Solomidou, Melpo

    2014-01-01

    Secoisolariciresinol diglucoside (SDG) is the major lignan in wholegrain flaxseed. However, extraction methods are complex and are associated with low yield and high costs. Using a novel synthetic pathway, our group succeeded in chemically synthesizing SDG (S,S and R,R enantiomers), which faithfully recapitulates the properties of their natural counterparts, possessing strong antioxidant and free radical scavenging properties. This study further extends initial findings by now investigating the DNA-radioprotective properties of the synthetic SDG enantiomers compared to the commercial SDG. DNA radioprotection was assessed by cell-free systems such as: (a) plasmid relaxation assay to determine the extent of the supercoiled (SC) converted to open-circular (OC) plasmid DNA (pBR322) after exposure of the plasmid to gamma radiation; and (b) determining the extent of genomic DNA fragmentation. Exposure of plasmid DNA to 25 Gy of ? radiation resulted in decreased supercoiled form and increased open-circular form, indicating radiation-induced DNA damage. Synthetic SDG (S,S) and SDG (R,R), and commercial SDG at concentrations of 25–250 ?M significantly and equipotently reduced the radiation-induced supercoiled to open-circular plasmid DNA in a dose-dependent conversion. In addition, exposure of calf thymus DNA to 50 Gy of gamma radiation resulted in DNA fragments of low-molecular weight (<6,000 bps), which was prevented in a dose-dependence manner by all synthetic and natural SDG enantomers, at concentrations as low as 0.5 ?M. These novel results demonstrated that synthetic SDG (S,S) and SDG (R,R) isomers and commercial SDG possess DNA-radioprotective properties. Such properties along with their antioxidant and free radical scavenging activity, reported earlier, suggest that SDGs are promising candidates for radioprotection for normal tissue damage as a result of accidental exposure during radiation therapy for cancer treatment. PMID:24945894

  19. Ionizing radiation induces immediate protein acetylation changes in human cardiac microvascular endothelial cells

    PubMed Central

    Barjaktarovic, Zarko; Kempf, Stefan J.; Sriharshan, Arundhathi; Merl-Pham, Juliane; Atkinson, Michael J.; Tapio, Soile

    2015-01-01

    Reversible lysine acetylation is a highly regulated post-translational protein modification that is known to regulate several signaling pathways. However, little is known about the radiation-induced changes in the acetylome. In this study, we analyzed the acute post-translational acetylation changes in primary human cardiac microvascular endothelial cells 4 h after a gamma radiation dose of 2 Gy. The acetylated peptides were enriched using anti-acetyl conjugated agarose beads. A total of 54 proteins were found to be altered in their acetylation status, 23 of which were deacetylated and 31 acetylated. Pathway analyses showed three protein categories particularly affected by radiation-induced changes in the acetylation status: the proteins involved in the translation process, the proteins of stress response, and mitochondrial proteins. The activation of the canonical and non-canonical Wnt signaling pathways affecting actin cytoskeleton signaling and cell cycle progression was predicted. The protein expression levels of two nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases, sirtuin 1 and sirtuin 3, were significantly but transiently upregulated 4 but not 24 h after irradiation. The status of the p53 protein, a target of sirtuin 1, was found to be rapidly stabilized by acetylation after radiation exposure. These findings indicate that post-translational modification of proteins by acetylation and deacetylation is essentially affecting the radiation response of the endothelium. PMID:25840449

  20. Composition, temperature and radiation induced changes in gamma irradiated AAAMPS copolymer

    NASA Astrophysics Data System (ADS)

    Rao, B. S.; Indira, S.; Sridhar, V.; Punnaiah, G.; Babu, B. S.; Subbakrishna, C.

    2005-06-01

    Effect of composition, temperature and radiation dose in gamma irradiated acrylamide-2-acrylamido-2-methyl propane sulphonic acid (AA) copolymer has been investigated by electron spin resonance (ESR) and fourier transform infrared (FTIR) techniques. ESR spectra of gamma irradiated AA copolymer have been recorded under different conditions. The observed ESR spectra are analysed by computer simulation techniques, to separate the constituent component spectra. Magnetic parameters employed to simulate the component spectra enabled the identification of corresponding free radicals. The AA copolymer with low acrylamide content composed of macroradicals of the type -CH2-CH-CH2- and methyl radicals (CH3) whereas the copolymer with high acryl amide content possess methyl radicals and radicals of the type -CH2-C(CONH2)-CH2-/CH3-C-CH3. Reasons for the variation in the formation of free radicals have been explained. The observed changes in ESR spectra of irradiated AA copolymer at higher temperatures are thought to be due to the recombination of free radicals. Formation of free radicals found to be enhanced with the increase in dose of irradiation. FTIR spectra of pure and irradiated copolymers have also confirmed the previous results.

  1. Gamma-radiation-induced degradation of actively pumped single-mode ytterbium-doped optical fibers

    NASA Astrophysics Data System (ADS)

    Singleton, B.; Petrosky, J.; Pochet, M.; Usechak, N. G.; Francis, S. A.

    2014-03-01

    The integration of optical components into the digital processing units of satellite subsystems has the potential to remove interconnect bottlenecks inherent to the volume, mass, complexity, reliability and crosstalk issues of copper-based interconnects. Assuming on-board high-bandwidth communications will utilize passive optical fibers as a communication channel, this work investigates the impact of gamma irradiation from a Co-60 source on both passive optical fibers and ytterbium-doped single-mode fibers operated as amplifiers for a 1060-nm light source. Standard optical patch cables were evaluated along with active Yb-doped double-clad fibers. Varied exposure times and signal transmission wavelengths were used to investigate the degradation of the fibers exposed to total doses above 100 krad (Si). The effect on the amplified signal gain was studied for the Yb-doped fibers. The increased attenuation in the fibers across a broad wavelength range in response to multiple levels of gamma radiation exposure along with the effect that the increased attenuation has on the actively pumped Yb-doped fiber amplifier performance, is discussed.

  2. Fabrication and mechanical characterization of biodegradable and synthetic polymeric films: Effect of gamma radiation

    NASA Astrophysics Data System (ADS)

    Akter, Nousin; Khan, Ruhul A.; Salmieri, Stephane; Sharmin, Nusrat; Dussault, Dominic; Lacroix, Monique

    2012-08-01

    Chitosan (1 wt%, in 2% aqueous acetic acid solution) and starch (1 wt%, in deionised water) were dissolved and mixed in different proportions (20-80 wt% chitosan) then films were prepared by casting. Tensile strength and elongation at break of the 50% chitosan containing starch-based films were found to be 47 MPa and 16%, respectively. It was revealed that with the increase of chitosan in starch, the values of TS improved significantly. Monomer, 2-butane diol-diacrylate (BDDA) was added into the film forming solutions (50% starch-based), then casted films. The BDDA containing films were irradiated under gamma radiation (5-25 kGy) and it was found that strength of the films improved significantly. On the other hand, synthetic petroleum-based polymeric films (polycaprolactone, polyethylene and polypropylene) were prepared by compression moulding. Mechanical and barrier properties of the films were evaluated. The gamma irradiated (25 kGy) films showed higher strength and better barrier properties.

  3. FY06 Annual Report: Amorphous Semiconductors for Gamma Radiation Detection (ASGRAD)

    SciTech Connect

    Johnson, Bradley R.; Riley, Brian J.; Crum, Jarrod V.; Sundaram, S. K.; Henager, Charles H.; Zhang, Yanwen; Shutthanandan, V.

    2007-01-01

    We describe progress in the development of new materials for portable, room-temperature, gamma-radiation detection at Pacific Northwest National Laboratory at the Hanford Site in Washington State. High Z, high resistivity, amorphous semiconductors are being designed for use as solid-state detectors at near ambient temperatures; principles of operation are analogous to single-crystal semiconducting detectors. Amorphous semiconductors have both advantages and disadvantages compared to single crystals, and this project is developing methods to mitigate technical problems and design optimized material for gamma detection. Several issues involved in the fabrication of amorphous semiconductors are described, including reaction thermodynamics and kinetics, the development of pyrolytic coating, and the synthesis of ingots. The characterization of amorphous semiconductors is described, including sectioning and polishing protocols, optical microscopy, X-ray diffraction, scanning electron microscopy, optical spectroscopy, particle-induced X-ram emission, Rutherford backscattering, and electrical testing. Then collaboration with the University of Illinois at Urbana-Champaign is discussed in the areas of Hall-effect measurements and current voltage data. Finally, we discuss the strategy for continuing the program.

  4. SIFTER: Scintillating Fiber Telescopes for Energetic Radiation, Gamma-Ray Applications

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    2002-01-01

    The research project "SIFTER: Scintillating Fiber Telescopes for Energetic Radiation, Gamma-Ray Applications" approved under the NASA High Energy Astrophysics Research Program. The principal investigator of the proposal was Prof. Geoffrey N. Pendleton, who is currently on extended leave from UAH. Prof. William S. Paciesas administered the grant during Dr. Pendleton's absence. The project was originally funded for one year from 6/8/2000 to 6/7/2001. Due to conflicts with other commitments by the PI, the period of performance was extended at no additional cost until 6/30/2002. The goal of this project was to study scintillating fiber pair-tracking gamma-ray telescope configurations specifically designed to perform imaging and spectroscopy in the 5 - 250 MeV energy range. The main efforts were concentrated in two areas: 1) development of tracking techniques and event reconstruction algorithms, with particular emphasis on angular resolution; and 2) investigation of coded apertures as a means to improve the instrument angular resolution at low energies.

  5. Effect of radiation on solid paracetamol: ESR identification and dosimetric features of gamma-irradiated paracetamol

    NASA Astrophysics Data System (ADS)

    Polat, M.; Korkmaz, M.

    2006-01-01

    In the present work, electron spin resonance (ESR) identification of gamma-irradiated paracetamol and its potential use as a normal and/or accidental dosimetric material were investigated in the dose range of 2.5-25 kGy. Both unirradiated paracetamol and mechanically ground vermidon samples exhibited a weak single resonance line at g = 2.0049 +/- 0.0006 and had Delta H-pp = 0.6 +/- 0.02 mT. Gamma irradiation produced an increase in signal intensity with a small hyperfine splitting in both paracetamol and vermidon and many weak resonance lines on both sides of a central line in the case of vermidon. Dose-response curves associated with central line of paracetamol and vermidon were found to follow polynomial and linear function, respectively. Simulation calculations based on the room temperature ESR intensity data of the paracetamol sample irradiated at 10 kGy were performed to determine the structure and spectral parameters of the radiation-induced radical species involved in the formation of the experimental ESR spectrum of paracetamol.

  6. HIV-1 Tat depresses DNA-PK{sub CS} expression and DNA repair, and sensitizes cells to ionizing radiation

    SciTech Connect

    Sun Yi [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing (China); Huang Yuechen [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing (China); Xu Qinzhi [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing (China); Wang Huiping [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing (China); Bai Bei [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing (China); Sui Jianli [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing (China); Zhou Pingkun [Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing (China)]. E-mail: zhoupk@nic.bmi.ac.cn

    2006-07-01

    Purpose There is accumulating evidence that cancer patients with human immmunodeficiency virus-1/acquired immunodeficency syndrome (HIV-1/AIDS) have more severe tissue reactions and often develop cutaneous toxic effects when subjected to radiotherapy. Here we explored the effects of the HIV-1 Tat protein on cellular responses to ionizing radiation. Methods and Materials Two Tat-expressing cell lines, TT2 and TE671-Tat, were derived from human rhabdomyosarcoma cells by transfecting with the HIV-1 tat gene. Radiosensitivity was determined using colony-forming ability. Gene expression was assessed by cDNA microarray and immunohybridization. The Comet assay and {gamma}-H2AX foci were use to detect DNA double-strand breaks (DSBs) and repair. Radiation-induced cell cycle changes were detected by flow cytometry. Results The radiosensitivity of TT2 and TE671-Tat cells was significantly increased as compared with parental TE671 cells or the control TE671-pCI cells. Tat also increased proliferation activity. The comet assay and {gamma}H2AX foci detection revealed a decreased capacity to repair radiation-induced DNA DSBs in Tat-expressing cells. Microarray assay demonstrated that the DNA repair gene DNA-PKcs, and cell cycle-related genes Cdc20, Cdc25C, KIF2C and CTS1 were downregulated in Tat-expressing cells. Depression of DNA-PKcs in Tat-expressing cells was further confirmed by RT-PCR and immuno-hybridization analysis. Tat-expressing cells exhibited a prolonged S phase arrest after 4 Gy {gamma}-irradiation, and a noticeable delay in the initiation and elimination of radiation-induced G{sub 2}/M arrest as compared with parental cells. In addition, the G{sub 2}/M arrest was incomplete in TT2 cells. Moreover, HIV-1 Tat resulted in a constitutive overexpression of cyclin B1 protein. Conclusion HIV-1 Tat protein sensitizes cells to ionizing radiation via depressing DNA repair and dysregulating cell cycle checkpoints. These observations provide new insight into the increased tissue reactions of AIDS cancer patients to radiotherapy.

  7. Evaluation of multijunction solar cell performance in radiation environments

    Microsoft Academic Search

    Dean C. Marvin; John C. Nocerino

    2000-01-01

    This report contains the results of the first systematic radiation study of five types of production multijunction solar cells. Cells optimized for beginning of life (BOL) efficiency were developed and obtained under the Air Force Manufacturing Technology (ManTech) program. These included GaInP2\\/GaAs two junction cells from Spectrolab, and GaInP2\\/GaAs\\/Ge three junction cells from both Spectrolab and TECSTAR. Additional two junction

  8. Shield optimization program. Part 4: Effects of neutron and gamma-ray radiations from nuclear weapons on SDI weapon platforms

    Microsoft Academic Search

    M. S. Smith; J. O. Johnson; T. A. Gabriel; J. M. Barnes; J. D. Drischler; R. T. Santoro

    1989-01-01

    Initial studies have been completed to estimate the radiation induced damage in silicon based electronic components onboard a representative Space Based Interceptor (SBI) weapon platform. The SBI weapon platform model used in the studies represents the author's concept of such a system. The analysis was completed for neutrons and gamma rays emanating from a nuclear weapon detonation in space. Results

  9. Cytological investigation of the effects of gamma radiation on cotton seeds with partial removal of the damaging effects

    Microsoft Academic Search

    Atakuziev

    1973-01-01

    The efficiency of the use of high and low temperatures for the partial ; reduction of the damaging effects of gamma radiation was tested on air-dried ; cotton seed of 108-F and S-4727 varieties of Gossypium hirsutum L. The seeds were ; irradiated with doses of 10, 40, and 80 kR at doses of 810 R\\/min. The seeds were ;

  10. INFLUENCE OF GAMMA RADIATION ON THERMAL PROPERTIES AND WATER VAPOR TRANSMISSION OF POLY(3- HYDROXYBUTYRATE) (PHB) IN BLENDS

    Microsoft Academic Search

    Pedro L. Forster; Natália A. Martins; Duclerc F. Parra

    2009-01-01

    Biodegradable polymers are a newly emerging field. A vast number of biodegradable polymers have been synthesized recently and some microorganisms and enzymes capable of degrading them have been identified. Polyesters such as poly(3-hydroxybutyrate) (PHB) or other polyhydroxyalkanoates (PHAs) have attracted commercial and academic interest as new biodegradable materials. In this work, we investigated the effect of gamma radiation on the

  11. A Novel Detector for Measuring Gamma-Ray Fluxes in a Mixed Pulsed Neutron-Gamma Radiation Fields

    Microsoft Academic Search

    Xiaoping Ouyang; Zhongbing Zhang; Qunshu Wang

    2007-01-01

    An ICI (insulator-conductor-insulator) gamma-ray detector designed for measurement of fast rising, high intensity pulsed gamma-ray fluxes has been developed. Like vacuum Compton diode (VCD) and dielectric Compton diode (DCD) devices, the ICI detector operates by utilization of the Compton effect. It has a very fast time response (rise time is less than 1 ns), a large linearity and a wide

  12. High energy gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.

    1974-01-01

    The SAS-2 gamma ray experiment and its detection of celestial gamma rays are described. Data also cover intensity of high energy gamma rays, gamma ray distribution, gamma ray origin, and diffuse radiation.

  13. The Role of Target and Bystander Cells in Dose-Response Relationship of Radiation-Induced Bystander Effects in Two Cell Lines

    PubMed Central

    Soleymanifard, Shokouhozaman; Bahreyni Toossi, Mohammad Taghi; Sazgarnia, Ameneh; Mohebbi, Shokoufe

    2013-01-01

    Objective(s): Radiation effect induced in nonirradiated cells which are adjacent or far from irradiated cells is termed radiation-induced bystander effect (RIBE). Published data on dose-response relationship of RIBE is controversial. In the present study the role of targeted and bystander cells in RIBE dose-response relationship of two cell lines have been investigated. Materials and Methods: Two cell lines (QU-DB and MRC5) which had previously exhibited different dose-response relationship were selected. In the previous study the two cell lines received medium from autologous irradiated cells and the results showed that the magnitude of damages induced in QU-DB cells was dependent on dose unlike MRC5 cells. In the present study, the same cells irradiated with 0.5, 2 and 4 Gy gamma rays and their conditioned media were transferred to nonautologous bystander cells; such that the bystander effects due to cross-interaction between them were studied. Micronucleus assay was performed to measure the magnitude of damages induced in bystander cells (RIBE level). Results: QU-DB cells exhibited a dose-dependent response. RIBE level in MRC5 cells which received medium from 0.5 and 2 Gy QU-DB irradiated cells was not statistically different, but surprisingly when they received medium from 4Gy irradiated QU-DB cells, RIBE was abrogated. Conclusion: Results pertaining to QU-DB and MRC5 cells indicated that both target and bystander cells determined the outcome. Triggering the bystander effect depended on the radiation dose and the target cell-type, but when RIBE was triggered, dose-response relationship was predominantly determined by the bystander cell type. PMID:24298387

  14. Effect of radiation combined with hyperthermia on human prostatic carcinoma cell lines in culture

    Microsoft Academic Search

    I. Kaver; J. L. Ware; J. D. Wilson; W. W. Jr. Koontz

    1991-01-01

    The effect of radiation combined with heat on three human prostatic carcinoma cell lines growing in vitro was investigated. Cells were exposed to different radiation doses followed by heat treatment at 43 degrees C for one hour. Heat treatment, given ten minutes after radiation, significantly enhanced the radiation response of all the cell lines studied. The combined effect of radiation

  15. The role of gamma delta T cells in immunity to Mycobacterium bovis infection in cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accumulating evidence suggests that gamma delta (gd) T cells play a critical role in the early response to M. bovis and may be key in bridging innate and adaptive immunity following infection. In vitro, gd T cells proliferate and produce robust amounts of IFNy in response to complex, protein and no...

  16. Determination of environmental radiation flux and organ doses using in-situ gamma spectroscopy

    NASA Astrophysics Data System (ADS)

    Al-Ghamdi, Abdulrahman S.

    Contamination of buildings represent a unique problem during Decontamination and Decommissioning (D&D) of nuclear facilities. It is necessary to determine the long-lived radionuclides and their respective specific activities in building materials before the right D&D decision can be made. At the same time, radiation risk of workers or potential occupants in the facility must be assessed as part of the D&D process. The goal of this project was to develop a methodology of obtaining gamma radiation flux and organ doses from in-situ gamma spectroscopy. Algorithms were developed to simulate the response functions of the HPGe detector and to convert the spectra into photon fluences. A Monte Carlo code, MCNP4C, was used to simulate HPGe detector response and to develop the conversion algorithm. The simulated spectra obtained for an HPGe detector were converted to flux using the algorithm for various different geometries. The response functions of the detector are presented in this document for the gamma energies from 60 keV to 2.2 MeV. Published fluence-to-dose conversion coefficients were used to calculate organ doses and effective dose equivalent. We then tested the theory at a 100-MeV linear electron accelerator at Rensselaer Polytechnic Institute (RPI). Samples of the activated concrete walls and floor in the target room of the Linac facility as well as some steel samples were taken to quantify the specific activities of the structures. The results show that the most important long-lived radionuclides include 22 Na, 46Sc, 54 Mn, 57Co, 60 Co, 65Zn, 152 Eu and 154Eu, depending on the location and composition of the material. The specific activities at the Linac facility range from 1.15E-01 to 765.31 muCi/Kg. The annual effective dose equivalent was assessed to be 2.44 mSv y-1 (0.244 rem y-1 ), which is about 5% of the Annual EDE limits to workers.

  17. Radiation tolerance of boron doped dendritic web silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rohatgi, A.

    1980-01-01

    The potential of dendritic web silicon for giving radiation hard solar cells is compared with the float zone silicon material. Solar cells with n(+)-p-P(+) structure and approximately 15% (AMl) efficiency were subjected to 1 MeV electron irradiation. Radiation tolerance of web cell efficiency was found to be at least as good as that of the float zone silicon cell. A study of the annealing behavior of radiation-induced defects via deep level transient spectroscopy revealed that E sub v + 0.31 eV defect, attributed to boron-oxygen-vacancy complex, is responsible for the reverse annealing of the irradiated cells in the temperature range of 150 to 350 C.

  18. Radiative efficiency of lead iodide based perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Tvingstedt, Kristofer; Malinkiewicz, Olga; Baumann, Andreas; Deibel, Carsten; Snaith, Henry J.; Dyakonov, Vladimir; Bolink, Henk J.

    2014-08-01

    The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.14 V closer to its radiative limit than the OPV cell. Additionally, and in contrast to OPVs, we show that the photoluminescence of the perovskite solar cell is substantially quenched under short circuit conditions in accordance with how an ideal photovoltaic cell should operate.

  19. Radiative efficiency of lead iodide based perovskite solar cells.

    PubMed

    Tvingstedt, Kristofer; Malinkiewicz, Olga; Baumann, Andreas; Deibel, Carsten; Snaith, Henry J; Dyakonov, Vladimir; Bolink, Henk J

    2014-01-01

    The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.14 V closer to its radiative limit than the OPV cell. Additionally, and in contrast to OPVs, we show that the photoluminescence of the perovskite solar cell is substantially quenched under short circuit conditions in accordance with how an ideal photovoltaic cell should operate. PMID:25317958

  20. ESR study of vacancy clusters produced by radiation damage in silicon and barium oxide. [Neutrons; gamma radiation

    SciTech Connect

    Yousif, H.N.

    1983-01-01

    The results of a study of defect cluster formation in two totally different insulating crystals; purely covalent silicon and highly ionic barium oxide are reported here. Elementary models of radiation damage in silicon relate the net defect production only to the total energy deposited in the lattice (Kinchin-Pease hypothesis). This hypothesis has been tested by monitoring electron spin resonance (ESR) signals of several dominant cluster defects, in high purity and in oxygen contaminated samples irradiated with two very different reactor spectra. The hypothesis fails. In neutron irradiated BaO crystals, a new paramagnetic defect is introduced by a sequence of annealing and gamma irradiation. It has been identified as belonging to adjacent barium and oxygen vacancies with a single trapped electron. Analysis of the hyperfine interactions with the five near neighbor bariums gives rise to a detailed interpretation of the electron wave function as that of a weakly perturbed F/sup +/ center in the electric field of the barium vacancy. A defect model is proposed to account for the hyperfine interactions. The defect is shown to be formed by thermally activated migration of the barium vacancy, with an activation energy of 1.26 +/- 0.15 eV.