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1

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

SciTech Connect

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.

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

1987-05-01

2

Gamma radiation increases endonuclease-dependent L1 retrotransposition in a cultured cell assay.  

PubMed

Long Interspersed Elements (LINE-1s, L1s) are the most active mobile elements in the human genome and account for a significant fraction of its mass. The propagation of L1 in the human genome requires disruption and repair of DNA at the site of integration. As Barbara McClintock first hypothesized, genotoxic stress may contribute to the mobilization of transposable elements, and conversely, element mobility may contribute to genotoxic stress. We tested the ability of genotoxic agents to increase L1 retrotransposition in a cultured cell assay. We observed that cells exposed to gamma radiation exhibited increased levels of L1 retrotransposition. The L1 retrotransposition frequency was proportional to the number of phosphorylated H2AX foci, an indicator of genotoxic stress. To explore the role of the L1 endonuclease in this context, endonuclease-deficient tagged L1 constructs were produced and tested for their activity in irradiated cells. The activity of the endonuclease-deficient L1 was very low in irradiated cells, suggesting that most L1 insertions in irradiated cells still use the L1 endonuclease. Consistent with this interpretation, DNA sequences that flank L1 insertions in irradiated cells harbored target site duplications. These results suggest that increased L1 retrotransposition in irradiated cells is endonuclease dependent. The mobilization of L1 in irradiated cells potentially contributes to genomic instability and could be a driving force for secondary mutations in patients undergoing radiation therapy. PMID:16507671

Farkash, Evan A; Kao, Gary D; Horman, Shane R; Prak, Eline T Luning

2006-01-01

3

Mutant quantity and quality in mammalian cells (AL) exposed to cesium-137 gamma radiation: effect of caffeine  

NASA Technical Reports Server (NTRS)

We examined the effect of caffeine (1,3,7-trimethylxanthine) on the quantity and quality of mutations in cultured mammalian AL human-hamster hybrid cells exposed to 137Cs 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- mutants by 137Cs gamma radiation. Molecular analysis of 235 S1- mutants using a series of DNA probes mapped to the human chromosome 11 in the AL hybrid cells revealed that 73 to 85% of the mutations in unexposed cells and in cells treated with caffeine alone, 137Cs gamma rays alone or 137Cs 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 "complex" mutations were rare for 137Cs 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 137Cs gamma irradiation.

McGuinness, S. M.; Shibuya, M. L.; Ueno, A. M.; Vannais, D. B.; Waldren, C. A.; Chatterjee, A. (Principal Investigator)

1995-01-01

4

Induction of micronuclei in human cell lines and primary cells by combination treatment with gamma-radiation and ethyl methanesulfonate.  

PubMed

While testing for genotoxicity is usually performed on single chemicals, exposure of humans often involves combinations of agents. Previous results from this laboratory showed supra-additivity for the induction of micronuclei in p53-mutated mouse lymphoma L5178Y cells after combined treatment with gamma-radiation from a 137Cs source and ethyl methanesulfonate (EMS). The question now was whether supra-additivity was a general phenomenon for the genotoxicity of this combination of a physical and a chemical DNA-damaging agent or whether the result was species- and cell type-specific. The same combination of agents was investigated in two human lymphoblastoid cell lines, TK6 (wild-type p53) and WTK1 (mutated p53), and primary fibroblasts from a fetal human lung. Doses were in the linear dose-effect range, resulting in a 1.5- to 3-fold increase in micronuclei above control. Radiation doses were between 125 and 350 mGy, while the EMS concentrations were 20-50 microg/ml for the cell lines and 250-350 microg/ml for the primary cells. In none of the human test systems was supra-additivity observed. With the WTK1 cells, which are most similar to the mouse cells regarding p53 status, there was even a tendency for a sub-additive combination effect. Possible explanations for the difference to the mouse cells could be related to species-specific aspects, different consequences of the p53 mutations or the presence of additional mutations. It is concluded that caution is advised in the interpretation and extrapolation of experimental results of mixture toxicity data because the outcome could be highly specific for the given selection of agents, doses and assays. PMID:11880548

Stopper, Helga; Lutz, Werner K

2002-03-01

5

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

SciTech Connect

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.

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

1995-06-01

6

REDD1 Protects Osteoblast Cells from Gamma Radiation-Induced Premature Senescence  

Microsoft Academic Search

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

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

2012-01-01

7

Gamma radiation induced cell cycle perturbations and DNA damage in Catla Catla as measured by flow cytometry.  

PubMed

Gamma radiation induced cell cycle perturbations and DNA damage in Catla catla were analyzed in erythrocytes at different time points using flow cytometry (FCM). Protracted exposure to radiation induced damage between days 12 and 45. Disturbances in cell cycle machinery, i.e., proportional increase and decrease in Gap0 or quiescent/Gap1 (G0/G1), Synthesis (S) and Gap2/Mitotic (G2/M) phases were observed at both acute and protracted treatments. Both acute and protracted exposures induced apoptosis with a notable significance between days 3 and 6 at protracted and on day 45 at acute doses. Fish exposed protractedly avail some DNA repair mechanisms than acutely exposed. This is the first study to analyze radiation induced DNA damage under laboratory conditions and suggests that flow cytometry can also be an alternate tool to screen genotoxicity induced by ionizing radiation in fish. PMID:25483367

Anbumani, S; Mohankumar, Mary N

2015-03-01

8

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

PubMed Central

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

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

2014-01-01

9

Diffuse gamma radiation  

NASA Technical Reports Server (NTRS)

An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy.

Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

1977-01-01

10

Effect of gamma and UV-B\\/C radiation on plant cells  

Microsoft Academic Search

The biological effect of gamma-rays is based on the interaction with atoms or molecules in the cell, particularly water, to produce free radicals, which can damage different important compounds of plant cell. The UV-B\\/C photons have enough energy to destroy chemical bounds, causing a photochemical reaction. The biological effect is due to these processes. This paper is focused on the

E Kovács; Á Keresztes

2002-01-01

11

Gamma radiation field intensity meter  

DOEpatents

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.

Thacker, Louis H. (Knoxville, TN)

1995-01-01

12

Gamma radiation field intensity meter  

DOEpatents

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.

Thacker, L.H.

1995-10-17

13

Gamma radiation field intensity meter  

DOEpatents

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.

Thacker, Louis H. (Knoxville, TN)

1994-01-01

14

Gamma radiation field intensity meter  

DOEpatents

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.

Thacker, L.H.

1994-08-16

15

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

PubMed

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

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

2014-05-15

16

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

PubMed Central

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

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

2014-01-01

17

DNA sequence analysis of gamma radiation-induced deletions and insertions at the APRT locus of hamster cells  

SciTech Connect

Gamma radiation-induced gene rearrangements at the Chinese hamster ovary cell locus coding for the purine salvage enzyme adenine phosphoribosyl transferase (APRT) consist of both simple deletions and more complex alterations that are presumably the result of multiple strand breaks. To characterize these mutations at the DNA sequence level, fragments altered by deletion and insertion mutations were obtained by cloning in lambda phage vectors or by using the polymerase chain reaction. The radiation-induced deletions characterized here eliminate 3-4 kb and have at least one breakpoint in an AT-rich region or near short direct or inverted repeats. Insertions involve small fragments (102 and 456 bp) of repetitive DNA that appear to be related to B2 (short interspersed repetitive) and long interspersed repeat families. The novel fragments bear little resemblance to each other or to sequences at the integration sites, and their introduction is accompanied by a small target site deletion.

Miles, C.; Sargent, G.; Phear, G.; Meuth, M. (Imperial Cancer Research Fund, Clare Hall Laboratories, Hertfordshire (England))

1990-01-01

18

Gamma radiation from radio pulsars  

NASA Technical Reports Server (NTRS)

The probable magnetospheric location and source of the gamma ray emission from some young radiopulsars is discussed. The suggested evolution of this emission as a function of pulsar period gives a diminished gamma-ray luminosity for a more rapidly spinning pre-Crab pulsar. A greatly enhanced one, similar to that of unidentified Cos B sources, is predicted for a slightly slower post-Vela pulsar, followed by a relatively rapid quenching of the gamma-ray luminosity at still longer periods. Possible anomalous exo-magnetospheric pulsed MeV and TeV-PeV radiation from the Crab pulsar is considered.

Ruderman, Malvin

1990-01-01

19

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

SciTech Connect

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.

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

20

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

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.

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

21

The PARP-1 Inhibitor Olaparib Causes Retention of ?-H2AX Foci in BRCA1 Heterozygote Cells Following Exposure to Gamma Radiation  

E-print Network

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A novel treatment for cancer patients with homozygous deletions of BRCA1 and BRCA2 is to use drugs that inhibit the enzyme poly(ADP-ribose) polymerase (PARP). Specific inhibition of PARP-1 can induce synthetic lethality in irradiated cancer cells while theoretically leaving normal tissue unaffected. We recently demonstrated in a cell survival assay that lymphoblastoid cells with mono-allelic mutations of BRCA1 were hypersensitive to gamma radiation in the presence of the PARP-1 inhibitor Olaparib compared to normal cells and mono-allelic BRCA2 cells. To determine if the enhanced radiation sensitivity was due to a persistence of DNA strand breaks, we performed ?-H2AX foci analysis in cells derived from two normal individuals, three heterozygous BRCA1 and three heterozygous BRCA2 cell lines. Cells were exposed to 2 Gy gamma radiation in the presence or absence of 5 µM Olaparib. Using immunofluorescence and imaging flow cytometry, foci were measured in untreated cells and at 0.5, 3, 5 and 24 hours post-irradiation. In all lymphoblastoid cells treated with 2 Gy gamma radiation, there was a predictable induction of DNA strand breaks, with a modest but significant retention of foci over 24 hours in irradiated cells treated with Olaparib (ANOVA P < 0.05). However, in mono-allelic BRCA1 cells, there was a failure to fully repair DNA double-strand breaks (DSB) in the presence

Emma C. Bourton; Piers N. Plowman; A J. Harvey; Sheba Adam Zahir; Christopher N. Parris

22

Gamma radiation characteristics of plutonium dioxide fuel  

NASA Technical Reports Server (NTRS)

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.

Gingo, P. J.

1969-01-01

23

Trypanosoma cruzi Gene Expression in Response to Gamma Radiation  

Microsoft Academic Search

Trypanosoma cruzi is an organism highly resistant to ionizing radiation. Following a dose of 500 Gy of gamma radiation, the fragmented genomic DNA is gradually reconstructed and the pattern of chromosomal bands is restored in less than 48 hours. Cell growth arrests after irradiation but, while DNA is completely fragmented, RNA maintains its integrity. In this work we compared the

Priscila Grynberg; Danielle Gomes Passos-Silva; Marina de Moraes Mourão; Roberto Hirata Jr; Andrea Mara Macedo; Carlos Renato Machado; Daniella Castanheira Bartholomeu; Glória Regina Franco

2012-01-01

24

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

PubMed

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

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

2009-07-01

25

Use of the comet assay to measure DNA damage in cells exposed to photosensitizers and gamma radiation  

NASA Astrophysics Data System (ADS)

We used the comet assay associated with DNA-glycosylases to estimate DNA damage in cells exposed to gamma irradiation or photosensitized either with methylene blue or orange acridine. A calibration performed using irradiation allowed the measurement of the steady-state level and the yield of 8-oxodGuo as well as strand breaks and alkali-labile sites. Nous avons utilisé la méthode des comètes associée à des ADN-glycosylases, pour estimer les dommages de l'ADN dans des cellules après l'exposition à un rayonnement gamma ou après photosensibilisation par le bleu de méthylène ou l'acridine orange. Une calibration de la méthode des comètes a permis de mesurer le niveau basal et les taux de formation de 8-oxodGuo ainsi que le nombre de cassures de brins et de sites alcali labiles.

Pouget, J.-P.; Ravanat, J.-L.; Douki, T.; Richard, M.-J.; Cadet, J.

1999-01-01

26

Apparatus and method for detecting gamma radiation  

DOEpatents

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.

Sigg, R.A.

1994-12-13

27

Apparatus and method for detecting gamma radiation  

DOEpatents

A high efficiency radiation detector 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.

Sigg, Raymond A. (Martinez, GA)

1994-01-01

28

Relative Biological Effectiveness (RBE) of 131I Radiation Relative to 60Co Gamma Rays  

PubMed Central

Objective: To assess relative biological effectiveness (RBE) of 131I radiation relative to 60Co gamma rays in glioblastoma spheroid cells. Materials and Methods: : In this experimental study, glioblastoma spheroid cells were exposed to 131I radiation and 60Co gamma rays. Radiation induced DNA damage was evaluated by alkaline comet assay. Samples of spheroid cells were treated by radiation from 131I for four different periods of time to find the dose-response equation. Spheroid cells were also exposed by 200 cGy of 60Co gamma rays as reference radiation to induce DNA damage as endpoint. Results: Resulted RBE of 131I radiation relative to 60Co gamma rays in 100 µm giloblastoma spheroid cells was equal to 1.16. Conclusion: The finding of this study suggests that 131I photons and electrons can be more effective than 60Co gamma rays to produce DNA damage in glioblastoma spheroid cells. PMID:24027663

Neshasteh-Riz, Ali; Mahmoud Pashazadeh, Ali; Mahdavi, Seyed Rabie

2013-01-01

29

In vitro cytophotometry evaluation of gamma-radiation effects on human sperm cell by acridine orange staining.  

PubMed

Effects of gamma-radiations on human sperm nuclei in vitro were studied by cytophotometrical quantification on fixed smears stained by acridine orange some of which had undergone heat-treatment. Following irradiations at different doses (0.0, 2.5, 5.0, 7.5 gy) using a cobalt source, changes in distribution of acridine orange fluorescences emitted by nuclei (total fluorescence greater than 515 nm versus green fluorescence = 525 nm) appeared to be dose-dependent. Heat-treatment of irradiated heads was confirmed to be a complementary procedure necessary for a good evaluation of the initial degree in chromatin compactness. Chromatin alterations related to changes in emitted fluorescence could be due to the initial fragility of the DNA-nucleoprotein complex. These preliminary results suggest that the normality of sperm chromatin could be used as a biologic dosimeter. PMID:1700651

Roux, C; Neveux, Y; Dadoune, J P

1990-01-01

30

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

SciTech Connect

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.

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

2011-04-18

31

Dibasic calcium phosphate dihydrate, USP material compatibility with gamma radiation  

NASA Astrophysics Data System (ADS)

Gamma radiation is a commonly used method to reduce the microbial bioburden in compatible materials when it is applied at appropriate dose levels. Gamma irradiation kills bacteria and mold by breaking down the organism’s DNA and inhibiting cell division. The purpose of this study is to determine the radiation dosage to be used to treat Dibasic Calcium Phosphate Dihydrate, USP (DCPD) and to evaluate its physicochemical effects if any, on this material. This material will be submitted to various doses of gamma radiation that were selected based on literature review and existing regulations that demonstrate that this method is effective to reduce or eliminate microbial bioburden in natural source and synthetic materials. Analytical testing was conducted to the DCPD exposed material in order to demonstrate that gamma radiation does not alter the physicochemical properties and material still acceptable for use in the manufacture of pharmaceutical products. The results obtained through this study were satisfactory and demonstrated that the gamma irradiation dosages from 5 to 30 kGy can be applied to DCPD without altering its physicochemical properties. These are supported by the Assay test data evaluation of lots tested before and after gamma irradiation implementation that show no significant statistical difference between irradiated and non irradiated assay results. The results of this study represent an achievement for the industry since they provide as an alternative the use of Gamma irradiation technology to control the microbial growth in DCPD.

Betancourt Quiles, Maritza

32

Gamma radiation background measurements from Spacelab 2  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

33

Radiolysis of sulfoxides. [Gamma radiation  

Microsoft Academic Search

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

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

2009-01-01

34

Cell Radiation Experiment System  

NASA Technical Reports Server (NTRS)

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.

Morrison, Dennis R.

2010-01-01

35

Inspection of cargo containers using gamma radiation  

NASA Astrophysics Data System (ADS)

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.

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

1997-02-01

36

Gamma-radiation (GR) triggers a unique gene expression profile associated with cell death compared to proton radiation (PR) in mice in vivo  

PubMed Central

Proton radiation (PR) therapy offers a number of potential advantages over conventional (photon) ?-radiation (GR) therapy for cancer, due to a more localized delivery of the radiation dose. However, the pathophysiological effects following PR-exposure are less well characterized than those of GR-exposure and the molecular changes associated with the acute apoptotic effects in mice in vivo following PR have not been elucidated. Previous studies have estimated the RBE of protons for various in vivo and in vitro endpoints at between 1.1 and 1.3. We assumed an RBE of 1.1 for the endpoints to be evaluated in these studies. Based on this assumption, ICR mice were treated with whole-body doses of GR (1.1 and 7.0 Gy) and PR (1.0 and 6.4 Gy) that were expected to represent RBE-weighted doses. The bone marrow, thymus, spleen and GI-tract were isolated and processed for histology and immunohistochemistry. The apoptotic responses varied greatly between GR and PR in a tissue- and dose-dependent manner. Surprisingly, cell death in the splenic white pulp was consistently lower in PR-treated animals compared to animals treated with GR. This was in spite of an increased presence of damaged DNA following PR as determined by staining for ?H2AX and phospho-ATM. Interestingly, both PR and GR triggered nuclear accumulation of p53 and no significant differences were found in the majority of the known pro-apoptotic p53-target genes in the spleens of treated mice. However, GR uniquely triggered a pro-apoptotic expression profile including expression of the pro-apoptotic, p53- and interferon stimulated target gene Bcl-G. In contrast to PR, GR may, in a cell type specific manner, trigger a more diverse non-random stress-response that mediates apoptosis partially independent of the extent of DNA damage. PMID:19106632

Finnberg, Niklas; Wambi, Chris; Ware, Jeffrey H.; Kennedy, Ann R.; El-Deiry, Wafik S.

2013-01-01

37

Field Deployable Gamma Radiation Detectors for DHS Use  

SciTech Connect

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.

Sanjoy Mukhopadhyay

2007-08-31

38

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)

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.

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

2001-01-01

39

Composition and apparatus for detecting gamma radiation  

DOEpatents

A gamma radiation detector and a radioluminiscent composition for use therein. The detector includes a radioluminscent 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.

Hofstetter, Kenneth J. (Aiken, SC)

1994-01-01

40

Composition and apparatus for detecting gamma radiation  

DOEpatents

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.

Hofstetter, K.J.

1994-08-09

41

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

42

GammaCam{trademark} radiation imaging system  

SciTech Connect

GammaCam{trademark}, a gamma-ray imaging system manufactured by AIL System, Inc., would benefit a site that needs to locate radiation sources. It is capable of producing a two-dimensional image of a radiation field superimposed on a black and white visual image. Because the system can be positioned outside the radiologically controlled area, the radiation exposure to personnel is significantly reduced and extensive shielding is not required. This report covers the following topics: technology description; performance; technology applicability and alternatives; cost; regulatory and policy issues; and lessons learned. The demonstration of GammaCam{trademark} in December 1996 was part of the Large-Scale Demonstration Project (LSDP) whose objective is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) Chicago Pile-5 Research Reactor (CP-5). The purpose of the LSDP is to demonstrate that by using innovative and improved decontamination and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies.

NONE

1998-02-01

43

30 CFR 57.5047 - Gamma radiation surveys.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Gamma radiation surveys. 57.5047 Section 57...METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047...

2013-07-01

44

30 CFR 57.5047 - Gamma radiation surveys.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Gamma radiation surveys. 57.5047 Section 57...METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047...

2010-07-01

45

30 CFR 57.5047 - Gamma radiation surveys.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Gamma radiation surveys. 57.5047 Section 57...METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047...

2012-07-01

46

30 CFR 57.5047 - Gamma radiation surveys.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Gamma radiation surveys. 57.5047 Section 57...METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047...

2014-07-01

47

30 CFR 57.5047 - Gamma radiation surveys.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Gamma radiation surveys. 57.5047 Section 57...METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047...

2011-07-01

48

Intrinsic radiation resistance in human chondrosarcoma cells  

SciTech Connect

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.

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

49

Afterglow Radiation from Gamma Ray Bursts  

SciTech Connect

Gamma-ray bursts (GRB) are huge fluxes of gamma rays that appear randomly in the sky about once a day. It is now commonly accepted that GRBs are caused by a stellar object shooting off a powerful plasma jet along its rotation axis. After the initial outburst of gamma rays, a lower intensity radiation remains, called the afterglow. Using the data from a hydrodynamical numerical simulation that models the dynamics of the jet, we calculated the expected light curve of the afterglow radiation that would be observed on earth. We calculated the light curve and spectrum and compared them to the light curves and spectra predicted by two analytical models of the expansion of the jet (which are based on the Blandford and McKee solution of a relativistic isotropic expansion; see Sari's model [1] and Granot's model [2]). We found that the light curve did not decay as fast as predicted by Sari; the predictions by Granot were largely corroborated. Some results, however, did not match Granot's predictions, and more research is needed to explain these discrepancies.

Desmond, Hugh; /Leuven U. /SLAC

2006-08-28

50

Cryo-gamma radiation inactivation of bovine herpesvirus type-1  

NASA Astrophysics Data System (ADS)

The radioresistance of bovine herpesvirus-1 (BHV-1), commonly known as infectious bovine rhinotracheitis virus (IBRV), suspended in free serum Glasgow-MEM medium and frozen at -78°C was studied. The number of surviving virus at a given dose of gamma-radiation was determined by a plaque assay system. D 10 values were calculated before and after removal of cell debris. The D 10 values obtained were 4.72 kGy and 7.31 kGy before and after removal of cell debris, respectively. Our results indicate that the inactivated viral particles could be used for vaccine preparation or diagnostic reagents.

Degiorgi, C. Fernández; Smolko, E. E.; Lombardo, J. H.

1999-07-01

51

Fracture resistance of gamma radiation sterilized cortical bone allografts  

Microsoft Academic Search

Gamma radiation is widely used for sterilization of human cortical bone allografts. Previous studies have reported that cortical bone becomes brittle due to gamma radiation sterilization. This embrittlement raises concern about the performance of a radiation sterilized allograft in the presence of a stress concentration that might be surgically introduced or biologically induced. The purpose of this study was to

Ozan Akkus; Clare M. Rimnac

2001-01-01

52

Differentially Expressed Genes Associated with Low-Dose Gamma Radiation  

NASA Astrophysics Data System (ADS)

We have studied low dose radiation induced gene expression alterations in a primary human fibroblast cell line using Agilent's whole human genome microarray. Cells were irradiated with 60Co ?-rays (0; 0.1; 0.5 Gy) and 2 hours later total cellular RNA was isolated. We observed differential regulation of approximately 300-500 genes represented on the microarray. Of these, 126 were differentially expressed at both doses, among them significant elevation of GDF-15 and KITLG was confirmed by qRT-PCR. Based on the transcriptional studies we selected GDF-15 to assess its role in radiation response, since GDF-15 is one of the p53 gene targets and is believed to participate in mediating p53 activities. First we confirmed gamma-radiation induced dose-dependent changes in GDF-15 expression by qRT-PCR. Next we determined the effect of GDF-15 silencing on radiosensitivity. Four GDF-15 targeting shRNA expressing lentiviral vectors were transfected into immortalized human fibroblast cells. We obtained efficient GDF-15 silencing in one of the four constructs. RNA interference inhibited GDF-15 gene expression and enhanced the radiosensitivity of the cells. Our studies proved that GDF-15 plays an essential role in radiation response and may serve as a promising target in radiation therapy.

Hegyesi, Hargita; Sándor, Nikolett; Schilling, Boglárka; Kis, Enik?; Lumniczky, Katalin; Sáfrány, Géza

53

77 FR 62267 - Proposed Extension of Existing Information Collection; Gamma Radiation Surveys  

Federal Register 2010, 2011, 2012, 2013, 2014

...Existing Information Collection; Gamma Radiation Surveys AGENCY: Mine Safety and Health...SUPPLEMENTARY INFORMATION: I. Background Gamma radiation occurs where radioactive materials are...rocks, soils, and ground water. Gamma radiation hazards may be found near radiation...

2012-10-12

54

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

55

GAMMA RADIATION: A SANITATING TREATMENT OF AFB CONTAMINATED BEEKEEPING EQUIPMENT GAMMA RADIATION SANITATION IN BEEKEEPING MANAGEMENT  

Microsoft Academic Search

Although American Foulbrood is well known, this disease is still a relevant cause of beehive and economic losses to beekeepers. Gamma radiation from a Cobalt-60 source provides an effective means of treating AFB contaminated beekeeping material for its reuse in apiary. Contaminated equipment (hive, frames, wax, honey) was irradiated at three different dosages: 10, 15 and 25 kGray. The infectivity

Alessandra Baggio; Albino Gallina; Nicoletta Dainese; Chiara Manzinello; Franco Mutinelli; Giorgia Serra; Roberto Colombo; Emanuele Carpana; Anna Gloria Sabatini; Klaus Wallner; Roberto Piro; Emanuele Sangiorgi

56

Solar cell radiation handbook  

NASA Technical Reports Server (NTRS)

The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed 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. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

1982-01-01

57

Orchid flowers tolerance to gamma-radiation  

NASA Astrophysics Data System (ADS)

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.

Kikuchi, Olivia Kimiko

2000-03-01

58

A component of gamma-radiation-induced cell death in E. coli is programmed and interlinked with activation of caspase-3 and SOS response.  

PubMed

The current study deals with the molecular mechanism of radiation-induced cell death (RICD) in Escherichia coli. Irradiated E. coli cells displayed markers similar to those found in eukaryotic programmed cell death (PCD) such as caspase-3 activation and phosphatidylserine externalization. RICD was found to be suppressed upon pretreatment with sublethal concentrations of rifampicin or chloramphenicol, indicating the requirement of de novo gene expression. RICD was also found to be inhibited by cell permeable inhibitors of caspase-3 or poly (ADP-ribose) polymerase, indicating the involvement of PCD during RICD in E. coli. Radiation-induced SOS response was alleviated as observed with decrease in LexA level and also reduced cell filamentation frequency in the presence of caspase inhibitor. Further, the inhibitor-mediated rescue was not observed in single-gene knockouts of umuC, umuD, recB and ruvA, the genes which are associated with SOS response. This implies a linkage between SOS response and PCD in radiation-exposed E. coli cells. PMID:23807199

Wadhawan, Surbhi; Gautam, Satyendra; Sharma, Arun

2013-08-01

59

Haemopoietic cell renewal in radiation fields  

NASA Astrophysics Data System (ADS)

Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

1994-10-01

60

A Device for Search of Gamma-Radiation Intensive Sources at the Radiation Accident Condition  

SciTech Connect

The procedure designed for measuring angular distributions of gamma radiation and for search of gamma radiation intensive sources is described. It is based on application of the original multidetector device ShD-1, for measuring an angular distribution in a complete solid angle (4 pi). The calibration results and data on the angular distributions of intensity of gamma radiation at the roof of Chornobyl NPP ''Shelter'' are presented.

Batiy, Valeriy; Klyuchnykov, A; Kochnev, N; Rudko, Vladimir; shcherbin, vladimir; Yegorov, V; Schmieman, Eric A.

2005-08-08

61

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

SciTech Connect

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.

O'Neil, Peter

2009-05-15

62

[Cytotoxicity of PVC tubes sterilized in ethylene oxide after gamma radiation exposure].  

PubMed

Do materials sterilized using gamma rays become toxic when re-sterilized in ethylene oxide? This question guided the objective of this study, which was to investigate the potential cytotoxic effect of PVC sterilized by gamma radiation and re-sterilized with EO by the agar diffusion method in cell cultures. Nine PVC tubes were subjected to gamma radiation sterilization and were re-sterilized in EO. The tubes were divided into a total of 81 units of analysis that were tested so as to represent the internal and external surfaces and mass of each tube. It was concluded that the PVC materials sterilized in gamma radiation and re-sterilized in EO are not cytotoxic. PMID:23743920

de Souza, Rafael Queiroz; Graziano, Kazuko Uchikawa; Ikeda, Tamiko Ichikawa; Gonçalves, Cláudia Regina; Cruz, Aurea Silveira

2013-04-01

63

Gamma-ray pulsars: Radiation processes in the outer magnetosphere  

Microsoft Academic Search

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

Roger W. Romani

1996-01-01

64

Inactivation of rabies diagnostic reagents by gamma radiation  

SciTech Connect

Treatment of CVS-11 rabies adsorbing suspensions and street rabies infected mouse brains with gamma radiation resulted in inactivated reagents that are safer to distribute and use. These irradiated reagents were as sensitive and reactive as the nonirradiated control reagents.

Gamble, W.C.; Chappell, W.A.; George, E.H.

1980-11-01

65

Radiosensitivity and Induction of Apoptosis by High LET Carbon Ion Beam and Low LET Gamma Radiation: A Comparative Study  

PubMed Central

Cancer treatment with high LET heavy ion beam, especially, carbon ion beam (12C), is becoming very popular over conventional radiotherapy like low LET gamma or X-ray. Combination of Poly(ADP-ribose) polymerase (PARP) inhibitor with xenotoxic drugs or conventional radiation (gamma or X-ray) is the newer approach for cancer therapy. The aim of our study was to compare the radiosensitivity and induction of apoptosis by high LET 12C and low LET gamma radiation in HeLa and PARP-1 knocked down cells. We did comet assay to detect DNA breaks, clonogenic survival assay, and cell cycle analysis to measure recovery after DNA damage. We measured apoptotic parameters like nuclear fragmentation and caspase-3 activation. DNA damage, cell killing, and induction of apoptosis were significantly higher for 12C than gamma radiation in HeLa. Cell killing and apoptosis were further elevated upon knocking down of PARP-1. Both 12C and gamma induced G2/M arrest although the 12C had greater effect. Unlike the gamma, 12C irradiation affects DNA replication as detected by S-phase delay in cell cycle analysis. So, we conclude that high LET 12C has greater potential over low LET gamma radiation in killing cells and radiosensitization upon PARP-1 inhibition was several folds greater for 12C than gamma. PMID:25018892

Ghorai, Atanu; Bhattacharyya, Nitai P.; Sarma, Asitikantha; Ghosh, Utpal

2014-01-01

66

Radiosensitivity and Induction of Apoptosis by High LET Carbon Ion Beam and Low LET Gamma Radiation: A Comparative Study.  

PubMed

Cancer treatment with high LET heavy ion beam, especially, carbon ion beam ((12)C), is becoming very popular over conventional radiotherapy like low LET gamma or X-ray. Combination of Poly(ADP-ribose) polymerase (PARP) inhibitor with xenotoxic drugs or conventional radiation (gamma or X-ray) is the newer approach for cancer therapy. The aim of our study was to compare the radiosensitivity and induction of apoptosis by high LET (12)C and low LET gamma radiation in HeLa and PARP-1 knocked down cells. We did comet assay to detect DNA breaks, clonogenic survival assay, and cell cycle analysis to measure recovery after DNA damage. We measured apoptotic parameters like nuclear fragmentation and caspase-3 activation. DNA damage, cell killing, and induction of apoptosis were significantly higher for (12)C than gamma radiation in HeLa. Cell killing and apoptosis were further elevated upon knocking down of PARP-1. Both (12)C and gamma induced G2/M arrest although the (12)C had greater effect. Unlike the gamma, (12)C irradiation affects DNA replication as detected by S-phase delay in cell cycle analysis. So, we conclude that high LET (12)C has greater potential over low LET gamma radiation in killing cells and radiosensitization upon PARP-1 inhibition was several folds greater for (12)C than gamma. PMID:25018892

Ghorai, Atanu; Bhattacharyya, Nitai P; Sarma, Asitikantha; Ghosh, Utpal

2014-01-01

67

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

PubMed

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

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

2014-11-11

68

Distinguishing Neutrons and Gammas with MSL's Radiation Assessment Detector (RAD)  

NASA Astrophysics Data System (ADS)

The radiation environment on the Martian surface is a complex mixture of charged primary and secondary radiation and of neutral secondary radiation. This neutral component amounts to a significant fraction of the surface radiation field and consists of neutrons and gamma rays. The neutron component is especially important from a radiation protection point of view, but is experimentally difficult to distinguish from the gamma rays. The Radiation Assessment Detector (RAD) on Mars Science Laboratory's (MSL's) rover Curiosity measures both neutrons and gammas. It consists of a compact arrangement of a dense, more gamma-sensitive CsI sctintillator, and a high-proton-content plastic scintillator, which in turn is more sensitive to neutrons. Using sophisticated inversion techniques, the RAD measurements can be inverted to provide reliable estimates for the neutron and gamma spectra on Mars. In this work we will discuss the status of the inversion techniques and calibration data, and relate them with predictions for the neutral component of the Martian surface radiation field.

Guo, J.; Hassler, D.; Wimmer-Schweingruber, R. F.; Zeitlin, C.; Boettcher, S.; Martin, C.; Brinza, D.; Koehler, J.; Böhm, E.; Kharytonov, A.; Ehresmann, B.

2012-12-01

69

Effects of gamma radiation on snake venoms  

NASA Astrophysics Data System (ADS)

Ionizing radiation is able to detoxify several venoms, including snake venoms, without affecting significantly their immunogenic properties. Inn order to elucidate this phenomena, we conceived a comparative pharmacological study between native and irradiated (2,000 Gy) crotoxin, the main toxin of the South American rattlesnake Crotalus durissus terrificus. Crotoxin was isolated and purified by molecular exclusion chromatography, pI precipitation and, susbequentely submitted to irradiaiton. Gel filtration of the irradiated toxin resulted in some high molecular weight aggregates formation. Crotoxin toxicity decreased two folds after irradiation, as determined by LD 50 in mice. Native and irradiated crotoxin biodistribution ocured in the same general manner, with renal elimination. However, in contrast to irradiated crotoxin, the native form was initially retained in kidneys. A later concentration (2-3 hr) appeared in phagocytic mononuclear cells rich organs (liver and spleen) and neural junction rich organs (muscle and brain).

Nascimento, N.; Spencer, P. J.; Andrade, H. F.; Guarnieri, M. C.; Rogero, J. R.

1998-06-01

70

Trypanosoma cruzi Gene Expression in Response to Gamma Radiation  

PubMed Central

Trypanosoma cruzi is an organism highly resistant to ionizing radiation. Following a dose of 500 Gy of gamma radiation, the fragmented genomic DNA is gradually reconstructed and the pattern of chromosomal bands is restored in less than 48 hours. Cell growth arrests after irradiation but, while DNA is completely fragmented, RNA maintains its integrity. In this work we compared the transcriptional profiles of irradiated and non-irradiated epimastigotes at different time points after irradiation using microarray. In total, 273 genes were differentially expressed; from these, 160 were up-regulated and 113 down-regulated. We found that genes with predicted functions are the most prevalent in the down-regulated gene category. Translation and protein metabolic processes, as well as generation of precursor of metabolites and energy pathways were affected. In contrast, the up-regulated category was mainly composed of obsolete sequences (which included some genes of the kinetoplast DNA), genes coding for hypothetical proteins, and Retrotransposon Hot Spot genes. Finally, the tyrosyl-DNA phosphodiesterase 1, a gene involved in double-strand DNA break repair process, was up-regulated. Our study demonstrated the peculiar response to ionizing radiation, raising questions about how this organism changes its gene expression to manage such a harmful stress. PMID:22247781

Grynberg, Priscila; Passos-Silva, Danielle Gomes; Mourão, Marina de Moraes; Hirata Jr, Roberto; Macedo, Andrea Mara; Machado, Carlos Renato; Bartholomeu, Daniella Castanheira; Franco, Glória Regina

2012-01-01

71

SM22{alpha}-induced activation of p16{sup INK4a}/retinoblastoma pathway promotes cellular senescence caused by a subclinical dose of {gamma}-radiation and doxorubicin in HepG2 cells  

SciTech Connect

Research highlights: {yields} SM22{alpha} overexpression in HepG2 cells leads cells to a growth arrest state, and the treatment of a subclinical dose of {gamma}-radiation or doxorubicin promotes cellular senescence. {yields} SM22{alpha} overexpression elevates p16{sup INK4a} followed by pRB activation, but there are no effects on p53/p21{sup WAF1/Cip1} pathway. {yields} SM22{alpha}-induced MT-1G activates p16{sup INK4a}/pRB pathway, which promotes cellular senescence by damaging agents. -- Abstract: Smooth muscle protein 22-alpha (SM22{alpha}) is known as a transformation- and shape change-sensitive actin cross-linking protein found in smooth muscle tissue and fibroblasts; however, its functional role remains uncertain. We reported previously that SM22{alpha} overexpression confers resistance against anti-cancer drugs or radiation via induction of metallothionein (MT) isozymes in HepG2 cells. In this study, we demonstrate that SM22{alpha} overexpression leads cells to a growth arrest state and promotes cellular senescence caused by treatment with a subclinical dose of {gamma}-radiation (0.05 and 0.1 Gy) or doxorubicin (0.01 and 0.05 {mu}g/ml), compared to control cells. Senescence growth arrest is known to be controlled by p53 phosphorylation/p21{sup WAF1/Cip1} induction or p16{sup INK4a}/retinoblastoma protein (pRB) activation. SM22{alpha} overexpression in HepG2 cells elevated p16{sup INK4a} followed by pRB activation, but did not activate the p53/p21{sup WAF1/Cip1} pathway. Moreover, MT-1G, which is induced by SM22{alpha} overexpression, was involved in the activation of the p16{sup INK4a}/pRB pathway, which led to a growth arrest state and promoted cellular senescence caused by damaging agents. Our findings provide the first demonstration that SM22{alpha} modulates cellular senescence caused by damaging agents via regulation of the p16{sup INK4a}/pRB pathway in HepG2 cells and that these effects of SM22{alpha} are partially mediated by MT-1G.

Kim, Tae Rim; Lee, Hee Min; Lee, So Yong; Kim, Eun Jin; Kim, Kug Chan [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)] [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Paik, Sang Gi [Department of Biology, School of Biosciences and Biotechnology, Chungnam National University, Daejeon (Korea, Republic of)] [Department of Biology, School of Biosciences and Biotechnology, Chungnam National University, Daejeon (Korea, Republic of); Cho, Eun Wie, E-mail: ewcho@kribb.re.kr [Daejeon-KRIBB-FHCRC Cooperation Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon (Korea, Republic of); Kim, In Gyu, E-mail: igkim@kaeri.re.kr [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-09-10

72

Some Radiation Techniques Used in the GU-3 Gamma Irradiator  

NASA Astrophysics Data System (ADS)

Different radiation techniques, measurement of dose and its distibution throughout the irradiated materials are the main problems treated in this paper. The oscillometry method combined with the ionization chamber, as an absolute dosimeter, is used for calibration of routine ECB dosimeters. The dose uniformity, for the used radiation techniques in our GU-3 Gamma Irradiator with Cs-137, is from 93% up to 99%.

Dodbiba, Andon; Ylli, Ariana; Stamo, Iliriana; Kongjika, Efigjeni

2007-04-01

73

Alpha Gamma Hot Cell Facility  

E-print Network

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

Kemner, Ken

74

Proton and gamma radiation tests on nonlinear crystals.  

PubMed

We report on the results of proton and gamma irradiation tests performed on nonlinear crystals for second- (SHG) and third-harmonic generation. Beta-barium borate (BBO), lithium triborate (LBO), and KTP crystals were exposed to three different energies of proton radiation (8, 70, and 300 MeV) and incremental doses of gamma radiation (up to 139 krad) in order to investigate the change in SHG performance and transmission spectra. BBO and LBO crystals turned out to be a suitable choice for SHG under radiative conditions. PMID:11905572

Roth, Ulrich; Tröbs, Michael; Graf, Thomas; Balmer, Jürg E; Weber, Heinz P

2002-01-20

75

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

SciTech Connect

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.

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

76

High resolution room temperature ionization chamber xenon gamma radiation detector  

Microsoft Academic Search

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

Gary Tepper; Jon Losee

1995-01-01

77

Effect of gamma radiation on honey quality control  

NASA Astrophysics Data System (ADS)

Honey is one of the most complex substances produced by bees, mainly from the nectar of flowers. Gamma radiation is a technique that can be used to decrease the number of microbiological problems associated with food and increase the shelf life of certain products. The objective of this study was to verify the effect of gamma radiation with source of cobalto-60 (10 kGy) on some parameters used in honey quality control. Seven samples of pure honey were obtained from local markets in Sao Paulo, Brazil, in 2007. The methods used are in accordance with Brazilian Regulations. The physicochemical parameters analyzed were: moisture, HMF, free acidity, pH, sugars and ash. The results showed that gamma radiation, in the dose mentioned above, did not cause significant physicochemical alterations.

Bera, A.; Almeida-Muradian, L. B.; Sabato, S. F.

2009-07-01

78

SNAP-8 post shutdown gamma radiation approximations  

NASA Technical Reports Server (NTRS)

Detector responses were calculated for normalized sources in the Perkins and King energy group structure for a SNAP 8 power system on a NASA space station. Gamma decay rates were then calculated by using an expanded, updated list of isotopic decay data, and from these, actual detector responses were found for the SNAP 8 system. The results indicate that energy-dependent calculations must be made to determine decay gamma dose rates for actual reactor configurations. A simplified method for making these calculations has been devised.

Byrn, N. R.; Smith, H. T.; Manning, H. S.

1972-01-01

79

Rejoining of gamma-radiation-induced single-strand breaks in plasmid DNA by human cell extracts: Dependence on the concentration of the hydroxyl radical scavenger, Tris  

SciTech Connect

The rejoining of single-strand breaks induced by {gamma} irradiation in plasmid DNA under different scavenging conditions is described using human cell extracts. As the scavenging capacity of the irradiated solution increases from 1.5 X 10{sup 7} to 3 X 10{sup 8} s{sup -1} using Tris-HCl as a scavenger, the ratio of single- to double-strand breaks is reduced from {approx}70:1 to 40:1. After irradiation, a proportion of DNA molecules have no initial strand breaks but contain damage that is converted to strand breaks when incubated either at 37{degrees}C or in the presence of cellular extract. Repair of damage by the extracts is dependent upon the scavenging capacity of the irradiated solution. Optimal rejoining is observed when the scavenging capacity is <1.5 X 10{sup 7} s{sup -1}, and results in the repair of some initial strand breaks. As the scavenging capacity increases to 3 X 10{sup 8} s{sup -1} the proportion of breaks repaired is significantly reduced. The relative increase in the yield of double-strand breaks and reduced repairability of single-strand breaks at a scavenging capacity of 3 X 10{sup 8} s{sup -1} is consistent with the concept that the severity of damage increases upon increasing the scavenger concentration. 26 refs., 5 figs., 1 tab.

Hodgkins, P.S.; Fairman, M.P.; O`Neill, P. [Medical Research Council Radiation and Genome Stability Unit, Harwell, Didcot, Oxon (United Kingdom)

1996-01-01

80

Annual effective dose from environmental gamma radiation in Bushehr city  

PubMed Central

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

2014-01-01

81

The Universe Viewed in Gamma-Rays 1 Evidence of TeV Gamma-Ray Radiation in Binary  

E-print Network

The Universe Viewed in Gamma-Rays 1 Evidence of TeV Gamma-Ray Radiation in Binary CYGNUS X-3 V-ALATOO mountain observatory (altitude 3338m), has been collecting Very High Energy gamma-ray data from Galactic structure on micro and macro scales. The gamma-astronomy is a unique experimental possibility of high

Enomoto, Ryoji

82

POLYMERIZATION OF RIBOMONONUCLEOTIDES BY $gamma$RADIATION  

Microsoft Academic Search

After gamma irradiation (0.9- 18.0 x 10⁴ r) of ; ribomononucleotides in aqueous solution a decrease in absorbancy at 260 m mu of ; at least two different components was observed. The decrease is an exponential ; function of the dose. Alkaline and enzymic hydrolysis with RNAase or ; phosphodiesterase of the irradiated samples produced an hyperchromic effect. ; Paper

G. Contreras; R. Espejo; E. Mery; A. Ohlbaum; J. Toha

1962-01-01

83

EFFECTS OF GAMMA RADIATION ON RIBONUCLEASE  

Microsoft Academic Search

Ribonuclease (RNase) has been inactivated by irradiation with gamma rays ; and by chemically generated OH radicals. Chromatographic patterns obtained from ; the two series of samples were very similar with respect to distribution of ; protein and also with respect to distribution of enzymic activity. The findings ; support the view that OH radicals are principal intermediates in the

E. Slobodian; M. Fleisher; W. Newman; S. Rubenfeld

1962-01-01

84

Gamma-delta t-cell lymphomas.  

PubMed

Gamma-delta T-cell lymphomas are aggressive and rare diseases originating from gamma-delta lymphocytes. These cells, which naturally play a role in the innate, non-specific immune response, develop from thymic precursor in the bone marrow, lack the major histocompatibility complex restrictions and can be divided into two subpopulations: Vdelta1, mostly represented in the intestine, and Vdelta2, prevalently located in the skin, tonsils and lymph nodes. Chronic immunosuppression such as in solid organ transplanted subjects and prolonged antigenic exposure are probably the strongest risk factors for the triggering of lymphomagenesis. Two entities are recognised by the 2008 WHO Classification: hepatosplenic gamma-delta T-cell lymphoma (HSGDTL) and primary cutaneous gamma-delta T-cell lymphoma (PCGDTL). The former is more common among young males, presenting with B symptoms, splenomegaly and thrombocytopenia, usually with the absence of nodal involvement. Natural behaviour of HSGDTL is characterised by low response rates, poor treatment tolerability, common early progression of disease and disappointing survival figures. PCGDTL accounts for <1% of all primary cutaneous lymphomas, occurring in adults with relevant comorbidities. Cutaneous lesions may vary, but its clinical behaviour is usually aggressive and long-term survival is anecdotal. Available literature on gamma-delta T-cell lymphomas is fractioned, mostly consisting of case reports or small cumulative series. Therefore, clinical suspicion and diagnosis are usually delayed, and therapeutic management remains to be established. This review critically analyses available evidence on diagnosis, staging and behaviour of gamma-delta T-cell lymphomas, provides recommendations for therapeutic management in routine practice and discusses relevant unmet clinical needs for future studies. PMID:25154298

Foppoli, Marco; Ferreri, Andrés J M

2015-03-01

85

Measurements of background gamma radiation on Spacelab 2  

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

86

Radiation burst from a single {gamma}-photon field  

SciTech Connect

The radiation burst from a single {gamma}-photon field interacting with a dense resonant absorber is studied theoretically and experimentally. This effect was discovered for the fist time by P. Helisto et al.[Phys. Rev. Lett. 66, 2037 (1991)] and it was named the ''gamma echo''. The echo is generated by a 180 Degree-Sign phase shift of the incident radiation field, attained by an abrupt change of the position of the absorber with respect to the radiation source during the coherence time of the photon wave packet. Three distinguishing cases of the gamma echo are considered; i.e., the photon is in exact resonance with the absorber, close to resonance (on the slope of the absorption line), and far from resonance (on the far wings of the resonance line). In resonance the amplitude of the radiation burst is two times larger than the amplitude of the input radiation field just before its phase shift. This burst was explained by Helisto et al. as a result of constructive interference of the coherently scattered field with the phase-shifted input field, both having almost the same amplitude. We found that out of resonance the scattered radiation field acquires an additional component with almost the same amplitude as the amplitude of the incident radiation field. The phase of the additional field depends on the optical thickness of the absorber and resonant detuning. Far from resonance this field interferes destructively with the phase-shifted incident radiation field and radiation quenching is observed. Close to resonance the three fields interfere constructively and the amplitude of the radiation burst is three times larger than the amplitude of the input radiation field.

Shakhmuratov, R. N. [Kazan Physical-Technical Institute, Russian Academy of Sciences, 10/7 Sibirsky Trakt, Kazan 420029 (Russian Federation); Department of Physics and Institute for Quantum Studies, TAMU, College Station, Texas 77843-4242 (United States); Vagizov, F. [Kazan Federal University, 18 Kremlyovskaya Street, Kazan 420008 (Russian Federation); Department of Physics and Institute for Quantum Studies, TAMU, College Station, Texas 77843-4242 (United States); Kocharovskaya, O. [Department of Physics and Institute for Quantum Studies, TAMU, College Station, Texas 77843-4242 (United States)

2011-10-15

87

Radiation effects in solar cells  

NASA Astrophysics Data System (ADS)

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.

Imaizumi, Mitsuru; Ohshima, Takeshi

2013-05-01

88

Primary stress responses in Arabidopsis thaliana exposed to gamma radiation.  

PubMed

As the environment is inevitably exposed to ionizing radiation from natural and anthropogenic sources, it is important to evaluate gamma radiation induced stress responses in plants. The objective of this research is therefore to investigate radiation effects in Arabidopsis thaliana on individual and subcellular level by exposing 2-weeks-old seedlings for 7 days to total doses of 3.9 Gy, 6.7 Gy, 14.8 Gy and 58.8 Gy and evaluating growth, photosynthesis, chlorophyll a, chlorophyll b and carotenoid concentrations and antioxidative enzyme capacities. While the capacity of photosystem II (PSII measured as Fv/Fm) remained intact, plants started optimizing their photosynthetic process at the lower radiation doses by increasing the PSII efficiency (?PSII) and the maximal electron transport rate (ETRmax) and by decreasing the non-photochemical quenching (NPQ). At the highest radiation dose, photosynthetic parameters resembled those of control conditions. On subcellular level, roots showed increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) capacities under gamma irradiation but catalase (CAT), syringaldazine peroxidase (SPX) and guaiacol peroxidase (GPX) activities, on the other hand, decreased. In the leaves no alterations were observed in SOD, CAT and SPX capacities, but GPX was highly affected. Based on these results it seems that roots are more sensitive for oxidative stress under gamma radiation exposure than leaves. PMID:24333636

Vanhoudt, Nathalie; Horemans, Nele; Wannijn, Jean; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde

2014-03-01

89

The role of contacts in semiconductor gamma radiation detectors  

Microsoft Academic Search

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

Uri Lachish

1998-01-01

90

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...

91

Gamma Radiation Induced Calibration Shift for Four Cryogenic Thermometer Types  

NASA Astrophysics Data System (ADS)

Cryogenic temperature sensors utilized in space environments are exposed to ionizing radiation with the total dose dependent upon the length of the mission. Based upon their minimal size and robust packaging, four models of cryogenic Resistance Thermometer Devices (RTDs) manufactured by Lake Shore Cryotronics, Inc. were tested to determine their reliability for space applications with regard to radiation. Samples of Cernox™ RTDs (CX-1050-SD), ruthenium oxide RTDs (models RX-102A-AA and RX-103A-AA), and silicon diode thermometers (model DT-670-SD) were irradiated at room temperature by a cesium-137 gamma source to total doses ranging from 5 Gy to 10 kGy. This paper presents the resulting temperature shifts induced by the gamma radiation as a function of total dose over the 1.4 K to 325 K temperature range. These data show that 1) Cernox™ RTDs exhibit high radiation hardness to 10 kGy from 1.4 K to 325 K, 2) ruthenium oxide RTDs show moderate radiation hardness to 10 kGy below 10 K, and 3) silicon diodes temperature sensors exhibit some radiation tolerance to low levels of radiation (especially below 70 K), but quickly shift calibration at radiation levels above 300 Gy, especially above 100 K.

Courts, S. Scott; Yeager, C. J.

2004-06-01

92

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

SciTech Connect

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.

Parra, S.A.

1994-11-30

93

Gamma Radiation from PSR B1055-52  

NASA Technical Reports Server (NTRS)

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.

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

94

Gamma Radiation from PSR B1055-52  

NASA Technical Reports Server (NTRS)

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.

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

95

Bioburden assessment and gamma radiation inactivation patterns in parchment documents  

NASA Astrophysics Data System (ADS)

Parchment documents are part of our cultural heritage and, as historical artifacts that they are, should be preserved. The aim of this study was to validate an appropriate methodology to characterize the bioburden of parchment documents, and to assess the growth and gamma radiation inactivation patterns of the microbiota present in that material. Another goal was to estimate the minimum gamma radiation dose (Dmin) to be applied for the decontamination of parchment as an alternative treatment to the current toxic chemical and non-chemical decontamination methods. Two bioburden assessment methodologies were evaluated: the Swab Method (SM) and the Destructive Method (DM). The recovery efficiency of each method was estimated by artificial contamination, using a Cladosporium cladosporioides spore suspension. The parchment samples' microbiota was typified using morphological methods and the fungal isolates were identified by ITS-DNA sequencing. The inactivation pattern was assessed using the DM after exposure to different gamma radiation doses, and using C. cladosporioides as reference. Based on the applied methodology, parchment samples presented bioburden values lower than 5×103 CFU/cm2 for total microbiota, and lower than 10 CFU/cm2 for fungal propagules. The results suggest no evident inactivation trend for the natural parchment microbiota, especially regarding the fungal community. A minimum gamma radiation dose (Dmin) of 5 kGy is proposed for the decontamination treatment of parchment. Determining the minimal decontamination dose in parchment is essential for a correct application of gamma radiation as an alternative decontamination treatment for this type of documents avoiding the toxicity and the degradation promoted by the traditional chemical and non-chemical treatments.

Nunes, Inês; Mesquita, Nuno; Cabo Verde, Sandra; Carolino, Maria Manuela; Portugal, António; Botelho, Maria Luísa

2013-07-01

96

Transmission of gamma radiation through heterogeneous media  

Microsoft Academic Search

The paper describes an experimental determination of the buildup factor in heterogeneous media consisting of different combinations of materials (polyethylene, Al, Fe, Pb) for an Isotropie Co60 point source (mean radiative energy 1.25 Mev). The experiment showed that the existing recommendations usually give unsatisfactory results in calculating dosages for shielding consisting of two layers of different materials, especially at large

D. L. Broder; Yu. P. Kayurin; A. A. Kutuzov

1962-01-01

97

Radiation effect on silicon transistors in mixed neutrons-gamma environment  

NASA Astrophysics Data System (ADS)

The effects of gamma and neutron irradiations on two different types of transistors, Junction Field Effect Transistor (JFET) and Bipolar Junction Transistor (BJT), were investigated. Irradiation was performed using a Syrian research reactor (RR) (Miniature Neutron Source Reactor (MNSR)) and a gamma source (Co-60 cell). For RR irradiation, MCNP code was used to calculate the absorbed dose received by the transistors. The experimental results showed an overall decrease in the gain factors of the transistors after irradiation, and the JFETs were more resistant to the effects of radiation than BJTs. The effect of RR irradiation was also greater than that of gamma source for the same dose, which could be because neutrons could cause more damage than gamma irradiation.

Assaf, J.; Shweikani, R.; Ghazi, N.

2014-10-01

98

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

SciTech Connect

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.

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

1983-03-01

99

Radiation effects on bacterial cells  

NASA Technical Reports Server (NTRS)

Study reveals the physicochemical and biochemical mechanisms which alter or modify the effects of high-energy radiation on living cells. An in-depth discussion is presented emphasizing the importance of optimizing bacterial treatment with glycerol.

Powers, E. L.

1968-01-01

100

Observations of diffuse galactic gamma radiation  

SciTech Connect

A new window for studying our Galaxy has emerged after over two decases of concerted effort with satellite and balloon-borne gammay-ray experiments. These experiments have discovered what appears to be a diffuse glow along the Galactic plane in lines at 0.511 and 1.809 MeV. I summarize these observations, with emphasis on measurements made with the Gamma-Ray Spectrometer (GRS) on NASA's Solar Maximum Mission satellite (SMM). The GRS is currently being used to study other diffuse Galactic emissions including the positronium continuum, radioactive lines from recent supernovae and novae, and de-excitation lines from interactions of cosmic-ray protons with interstellar carbon and oxygen.

Share, G.H.

1988-09-25

101

Gamma radiation resistant Fabry-Perot fiber optic sensors  

NASA Astrophysics Data System (ADS)

The Nuclear Regulatory Commission (NRC) in 1998 completed a study of emerging technologies that could be applicable to measurement systems in nuclear power plants [H. M. Hashemian [et al.], "Advanced Instrumentation and Maintenance Technologies for Nuclear Power Plants," NUREG/CR-5501 (1998)]. This study concluded that advanced fiber optic sensing technology is an emerging technology that should be investigated. It also indicated that there had been very little research related to performance evaluation of fiber optic sensors in nuclear plant harsh environments, although substantial research has been performed on nuclear radiation effects on optical fibers in the last two decades. A type of Fabry-Perot fiber optic temperature sensor, which is manufactured by Fiso Technologies in Canada, is qualified to be a candidate for potential applications in nuclear radiation environment due to its unique signal processing technique and its resistance to power loss. The gamma irradiation effects on this type of sensors are investigated in this article. Two sensors were irradiated in a gamma irradiation field and one of them was irradiated up to a total gamma dose of 133 Mrad. The sensor on-line performance was monitored during each gamma irradiation test. Furthermore, the sensor static and dynamic performance before and after each irradiation test were evaluated according to the Standard ISA-dS67.06.01 ("Performance Monitoring for Nuclear Safety-Related Instrument Channels in Nuclear Power Plants", Standard ISA-dS67.06.01, Draft 7, Instrument Society of America, 1999). Although several abnormal phenomena were observed, analysis shows that gamma irradiation is not accredited to the abnormal behavior, which implies that this type of sensor is suitable to a gamma irradiation environment with a high gamma dose.

Liu, Hanying; Miller, Don W.; Talnagi, Joseph

2002-08-01

102

Gamma radiation survey of the LDEF spacecraft  

NASA Technical Reports Server (NTRS)

The retrieval of the Long Duration Exposure Facility spacecraft in January 1990 after nearly six years in orbit offered a unique opportunity to study the long term buildup of induced radioactivity in the variety of materials on board. We conducted the first complete gamma-ray survey of a large spacecraft on LDEF shortly after its return to earth. A surprising observation was the Be-7 activity which was seen primarily on the leading edge of the satellite, implying that it was picked up by LDEF in orbit. This is the first known evidence for accretion of a radioactive isotope onto an orbiting spacecraft. Other isotopes observed during the survey, the strongest being Na-22, are all attributed to activation of spacecraft components. Be-7 is a spallation product of cosmic rays on nitrogen and oxygen in the upper atmosphere. However, the observed density is much greater than expected due to cosmic-ray production in situ. This implies transport of Be-7 from much lower altitudes up to the LDEF orbit.

Phillips, G. W.; King, S. E.; August, R. A.; Ritter, J. C.; Cutchin, J. H.; Haskins, P. S.; Mckisson, J. E.; Ely, D. W.; Weisenberger, A. G.; Piercey, R. B.

1992-01-01

103

Thermal stability of grafted fibers. [Gamma radiation  

SciTech Connect

Presented the experimental results on the study of thermal stability of grafted fibers, i.e., polypropylene-, polyester-, and rayon-grafted fibers. These fibers were obtained by radiation grafting processes using hydrophylic monomers such as 1-vinyl 2-pyrolidone, acrylic acid, N-methylol acrylamide, and acrylonitrile. The thermal stability of the fibers was studied using a Shimadzu Thermal Analyzer DT-30. The thermal stability of the fibers, which can be indicated by the value of the activation energy for thermal degradation, was not improved by radiation grafting. The degree of improvement depends on the thermal stability of the monomers used for grafting. The thermal stability of a polypropylene fiber, either a grafted or an ungrafted one, was found to be inferior compared to the polyester of a rayon fiber, which may be due to the lack of C=O and C=C bonds in the polypropylene molecules. The thermal stability of a fiber grafted with acrylonitrile monomer was found to be better than that of an ungrafted one. However, no improvement was detected in the fibers grafted with 1-vinyl 2-pyrrolidone monomer, which may be due to the lower thermal stability of poly(1-vinyl-2-pyrrolidone), compared to the polypropylene or polyester fibers. 17 figures, 3 tables.

Sundardi, F.; Kadariah; Marlianti, I.

1983-10-01

104

Mechanisms of radiation-induced neoplastic cell transformation  

SciTech Connect

Studies with cultured mammalian cells demonstrated clearly that radiation can transform cells directly and can enhance the cell transformation by oncogenic DNA viruses. In general, high-LET heavy-ion radiation can be more effective than X and gamma rays in inducing neoplastic cell transformation. Various experimental results indicate that radiation-induced DNA damage, most likely double-strand breaks, is important for both the initiation of cell transformation and for the enhancement of viral transformation. Some of the transformation and enhancement lesions can be repaired properly in the cell, and the amount of irrepairable lesions produced by a given dose depends on the quality of radiation. An inhibition of repair processes with chemical agents can increase the transformation frequency of cells exposed to radiation and/or oncogenic viruses, suggesting that repair mechanisms may play an important role in the radiation transformation. The progression of radiation-transformed cells appears to be a long and complicated process that can be modulated by some nonmutagenic chemical agents, e.g., DMSO. Normal cells can inhibit the expression of transforming properties of tumorigenic cells through an as yet unknown mechanism. The progression and expression of transformation may involve some epigenetic changes in the irradiated cells. 38 references, 15 figures, 1 table.

Yang, T.C.H.; Tobias, C.A.

1984-04-01

105

[FTIR analysis of Sr2+ biosorption by Bacillus spp. strains isolated from soil treated with gamma-ray radiation].  

PubMed

One strain bacterium was isolated from purple soil of Sichuan basin. It was subject to Bacillus according to analysis results of 16S rDNA. The effect of its biosorption to Sr2+ under gamma-ray radiation was studied in this paper. As for the whole kinetic biosorption curves, the results show that bacterial growth rates of test groups have retardation phenomena compared to the control groups without radiation. Such as the appearance of biosorption equilibrium retarded 1.5 d while the max growth rate retarded 0.5 d after the radiation SEM analysis showed that the bacterial cells had abnormity distortion after radiation. This proved that gamma-ray radiation can bring obvious damage to experimental bacterial cells. FTIR analysis results indicated that bacteria cells were damaged by radiation and Sr2+ has cooperation damage effects with radiation in aqueous condition, and the bacterial cells of log phase are easier to be damaged by coming forth radiation than those of lag phase. This radiation damage under different radiation condition mainly leads to that the characteristic peaks of amylase, protein amide and lipids on bacterial cells are slightly shifted. PMID:23427542

Dai, Qun-Wei; Dong, Fa-Qin; Wu, Xiao-Li; Li, Qiong-Fang

2012-12-01

106

Oxidation of naringenin by gamma-radiation  

NASA Astrophysics Data System (ADS)

The reaction of rad OH with naringenin (4',5,7-trihydroxyflavanone) in the presence of air induced the formation of the hydroxylation product eriodictyol (3',4',5,7-tetrahydroxyflavanone). Its yield was dependent on pH. The initial degradation yield of naringenin was Gi(-Nar)=(2.5±0.2)×10 -7 mol dm -3 J -1. For the reaction with rad OH, a rate constant k ( rad OH+naringenin)=(7.2±0.7)×10 9 M -1 s -1 was determined. In the presence of N 2O and NaN 3/N 2O, no eriodyctiol was formed. Apigenin (4',5,7-trihydroxyflavon) was detected as decay product of the naringenin phenoxyl radicals. In Ar-saturated solutions, naringenin exhibited a pronounced radiation resistance, G(-naringenin) ˜0.3×10 -7 mol dm -3 J -1.

Nagy, Tristan O.; Ledolter, Karin; Solar, Sonja

2008-06-01

107

Parity conserving gamma asymmetry in n-p radiative capture  

E-print Network

The importance of n-p radiative capture, utilizing polarized cold neutrons, as a means of measuring the weak pion coupling constant is reviewed. Parity conserving processes of the form k_gamma*[s_n,k_n] can contribute to the s_n*k_gamma photon asymmetry in any such experiment, if the apparatus is not perfectly symmetric. For an incident laboratory neutron energy of 0.003 eV a value of A^{PC}_{gamma}=0.67*10^{-8} is obtained for two different potential models (Argonne AV14 and Nijmegen Reid93). Serving as an extreme test case, the Reid soft core potential yields 0.61*10^{-8}, close to the result of the contemporary forces. Implications for extracting the weak pion coupling constant and for monitoring the beam polarization are discussed.

Attila Csoto; B. F. Gibson; G. L. Payne

1997-04-28

108

Characterization of gamma radiation inducible thioredoxin h from Spirogyra varians.  

PubMed

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

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

2013-08-15

109

Optical Sensors for Monitoring Gamma and Neutron Radiation  

NASA Technical Reports Server (NTRS)

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.

Boyd, Clark D.

2011-01-01

110

Gamma heating measurements in a mixed radiation field  

SciTech Connect

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.

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

111

Airborne gamma radiation soil moisture measurements over short flight lines  

NASA Technical Reports Server (NTRS)

Results are presented on airborne gamma radiation measurements of soil moisture condition, carried out along short flight lines as part of the First International Satellite Land Surface Climatology Project Field Experiment (FIFE). Data were collected over an area in Kansas during the summers of 1987 and 1989. The airborne surveys, together with ground measurements, provide the most comprehensive set of airborne and ground truth data available in the U.S. for calibrating and evaluating airborne gamma flight lines. Analysis showed that, using standard National Weather Service weights for the K, Tl, and Gc radiation windows, the airborne soil moisture estimates for the FIFE lines had a root mean square error of no greater than 3.0 percent soil moisture. The soil moisture estimates for sections having acquisition time of at least 15 sec were found to be reliable.

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

1990-01-01

112

The Gamma-ray galactic diffuse radiation and Cerenkov telescopes  

SciTech Connect

By using the PYTHIA version of the Lund Monte Carlo program, we study the photon yield of proton-proton collisions in the energy range between 10 GeV and 1 TeV. The resulting photon spectrum turns out to scale roughly with incident energy. Then, by folding the energy spectrum of cosmic-ray protons with the distribution of HI and CO, the Galactic diffuse emission of {gamma}-rays above 100 GeV is mapped. Prospects for observing that diffuse radiation with atmospheric Cerenkov telescopes are discussed. Present instruments are able to detect the {gamma}-ray glow of the Galactic center. The latter will be mapped by the next generation of telescopes if their energy threshold is decreased. However, a detailed survey of the Galactic ridge will be a real challenge, even in the long term. The MILAGRO project seems more appropriate. Finally, we investigate the {gamma}-ray emission from weakly interacting massive particles clustering at the Galactic center. It has been speculated that those species are a major component of the halo dark matter. We show that their {gamma}-ray signal is swamped in the Galactic diffuse radiation and cannot be observed at TeV energies. {copyright} {ital 1995 The American Astronomical Society.}

Chardonnet, P. [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France)] [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France); [Universite de Savoie, BP1104, 73011 Chambery Cedex (France); Salati, P. [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France)] [Theoretical Physics Group ENSLAPP, BP110, F-74941 Annecy-le-Vieux Cedex (France); [Universite de Savoie, BP1104, 73011 Chambery Cedex (France); [Institut Universitaire de France; Silk, J. [545 Campbell Hall, Astronomy Department, University of California at Berkeley, Berkeley, California 94720 (United States)] [545 Campbell Hall, Astronomy Department, University of California at Berkeley, Berkeley, California 94720 (United States); Grenier, I. [Departement dAstrophysique, Centre dEtudes Nucleaires de Saclay, F-91191 Gif-sur-Yvette Cedex (France)] [Departement dAstrophysique, Centre dEtudes Nucleaires de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Smoot, G. [Building 50, Room 205, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)] [Building 50, Room 205, Lawrence Berkeley Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States)

1995-12-01

113

Modeling the radiation doses from terrestrial gamma-ray flashes  

NASA Astrophysics Data System (ADS)

Terrestrial gamma-ray flashes (TGFs) are intense bursts of gamma-rays that originate from thunderclouds, from altitudes that commercial aircraft fly. Based upon the fluence of gamma-rays measured by the RHESSI spacecraft, Dwyer et al. [2010] inferred radiation doses to individuals inside aircraft in the 0.001 - 0.1 Sv range, depending upon the assumed size of the TGF source region. The largest doses occur when an aircraft is directly struck by the energetic electron beam that produces the TGF. The relativistic feedback discharge model is a self-consistent model that includes the generation of runaway electrons via the positron and x-ray feedback mechanisms and the electric field changes due to the resulting ionization and low-energy electron and ion currents. This model has successfully explained many properties of TGFs, including the gamma-ray intensities, durations, multi-pulsed structures as well as discharge currents and radio emissions. In this presentation we discuss new radiation dose calculations based upon the relativistic feedback discharge model and compare these calculations to previous work.

Dwyer, Joseph; Liu, Ningyu; Rassoul, Hamid

2013-04-01

114

Titanium-Water Thermosyphon Gamma Radiation Exposure and Results  

NASA Technical Reports Server (NTRS)

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some gamma irradiation. Noncondensable gas formation from radiation-induced breakdown of water over time may render portions of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature under accelerated gamma irradiation, with exposures on the same order of magnitude as that expected in 8 years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon: evaporator, condenser, and condenser end cap. Some noncondensable gas was evident; however, thermosyphon performance was not affected because the noncondensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of noncondensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the noncondensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of one thermosyphon in a vacuum chamber and at temperature revealed that the noncondensable gas diffused out of the thermosyphon over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

Sanzi, James, L.A; Jaworske, Donald, A.; Goodenow, Debra, A.

2012-01-01

115

Titanium-Water Thermosyphon Gamma Radiation Effects and Results  

NASA Technical Reports Server (NTRS)

Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some exposure to gamma irradiation. Non-condensable gas formation from radiation may breakdown water over time and render a portion of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature with accelerated gamma irradiation exposures on the same order of magnitude that is expected in eight years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon; evaporator, condenser, and condenser end cap. Some non-condensable gas was evident, however thermosyphon performance was not affected because the non-condensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of non-condensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the non-condensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of selected thermosyphons at temperature and in a vacuum chamber revealed that the non-condensable gas likely diffused out of the thermosyphons over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

Sanzi, James L.; Jaworske, Donald A.; Goodenow, Debra A.

2012-01-01

116

Effects of proton and gamma radiation on lymphocyte populations and acute response to antigen  

NASA Technical Reports Server (NTRS)

BACKGROUND: The clinical use of proton radiation in the management of cancer, as well as benign disorders, is rapidly increasing. The major goal of this study was to compare the effects of proton and gamma (60Co) radiation on cell-mediated and humoral immunological parameters. MATERIALS AND METHODS: C57BL/6 mice were exposed to a single dose of 3 Gray (Gy) protons or gamma-rays and intraperitoneally injected 1 day later with sheep red blood cells (sRBC). On 4, 10, 15, and 29 days after exposure, subsets from each group were euthanised; nonirradiated controls (with and without sRBC injection) were included. Body and relative spleen weights, leukocyte counts, spontaneous blastogenesis, lymphocyte populations, and anti-sRBC titers were evaluated. RESULTS: The data showed significant depression (p < 0.05) in nearly all assays on days 4 and 10 after irradiation. B lymphocytes (CD19+) were the most radiosensitive, although reconstitution back to normal levels was observed by day 15. T cell (CD3+) and T helper cell (CD4+) recovery was evident by day 29, whereas the T cytotoxic cell (CD8+) count remained significantly below normal. Natural killer cells (NK1.1+) were relatively radioresistant. Anti-sRBC antibody production was slow and low titers were obtained after irradiation. No significant differences were noted between the two types of radiation. CONCLUSIONS: Taken together, the data show that whole-body irradiation with protons or gamma-rays, at the dose employed, results in marked, but transient, immunosuppression. However, at the time points of testing and with the assays used, little or no differences were found between the two forms of radiation.

Kajioka, E. H.; Gheorghe, C.; Andres, M. L.; Abell, G. A.; Folz-Holbeck, J.; Slater, J. M.; Nelson, G. A.; Gridley, D. S.

1999-01-01

117

Effects of gamma-Radiation on Select Lipids and Antioxidants  

NASA Technical Reports Server (NTRS)

Radiation encountered on an extended duration space mission (estimates of 3 Sieverts for a mission to Mars) poses a threat not only to human health, but also to the quality, nutritional value, and palatability of the food system. Free radicals generated by radiation interaction with foods may initiate many unwanted reactions including: 1) autoxidation in lipids that alters flavor, odor, and concentrations of essential fatty acids, and 2) depletion of antioxidants food products and dietary supplements. Studies have shown that antioxidants may provide long term health protection from oxidative stress caused by radiation exposure; therefore, consumption of antioxidants will be important. Stability of essential fatty acids is also important for astronauts long-term health status. The objectives of this study were to characterize the effects of low dose gamma-radiation on lipids and antioxidants by monitoring oxidation and reducing power, respectively, in model systems. Select oils and antioxidants were exposed to levels of gamma-radiation ranging from 0 to 1000 Gy (1 Gy = 1 Sv) using a Gammacell 220 and stored at ambient or elevated temperatures (65 C) for up to 3 months prior to analysis. A Fricke dosimeter was used to verify differences between the radiation doses administered. Primary and secondary products of lipid oxidation in soybean and peanut oils were monitored using conjugated diene and 2-thiobarbituric acid (TBARs) assays. Changes in fatty acid composition and formation and vitamin E levels were also measured. The reducing power of antioxidant compounds, including vitamins C and E and beta-carotene, was determined using the ferric reducing antioxidant power (FRAP) assay. Significant differences (alpha =0.05) were present between all radiation doses tested using the Fricke dosimeter. Increasing radiation doses above 3 Sv resulted in significantly (alpha =0.05) elevated levels of oxidation and free fatty acids in soybean and peanut oils. Decreases in concentrations of essential fatty acids upon increasing radiation doses were also observed. Increasing radiation doses caused significant (alpha =0.05) decreases in reducing power and hence the effectiveness of vitamins C and E as well as beta-carotene. This work establishes a need for quantifying the effects of space relevant radiation doses in the development of a food system for an extended duration mission and for identifying threshold radiation levels that will impact the useful shelf-life of the variety of foods that will be sent. Eventual rancidity of lipids and the loss of antioxidant bioprotective effects are major concerns for the acceptability and nutritional profile of a food system.

Gandolph, Jacob; Mauer, Lisa; Perchonok, Michele

2006-01-01

118

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

Microsoft Academic Search

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

Heriberto Plaza-Rosado

1991-01-01

119

On the omnipresent background gamma radiation of the continuous spectrum  

NASA Astrophysics Data System (ADS)

The background spectrum of a germanium detector, shielded from the radiations arriving from the lower and open for the radiations arriving from the upper hemisphere, is studied by means of absorption measurements, both in a ground level and in an underground laboratory. The low-energy continuous portion of this background spectrum that peaks at around 100 keV, which is its most intense component, is found to be of very similar shape at the two locations. It is established that it is mostly due to the radiations of the real continuous spectrum, which is quite similar to the instrumental one. The intensity of this radiation is in our cases estimated to about 8000 photons/(m2s·2?·srad) in the ground level laboratory, and to about 5000 photons/(m2s·2?·srad) in the underground laboratory, at the depth of 25 m.w.e. Simulations by GEANT4 and CORSIKA demonstrate that this radiation is predominantly of terrestrial origin, due to environmental gamma radiations scattered off the materials that surround the detector (the "skyshine radiation"), and to a far less extent to cosmic rays of degraded energy.

Banjanac, R.; Maleti?, D.; Jokovi?, D.; Veselinovi?, N.; Dragi?, A.; Udovi?i?, V.; Ani?in, I.

2014-05-01

120

Evaluation of the spatial distribution of gammaH2AX following ionizing radiation.  

PubMed

An early molecular response to DNA double-strand breaks (DSBs) is phosphorylation of the Ser-139 residue within the terminal SQEY motif of the histone H2AX. This phosphorylation of H2AX is mediated by the phosphatidyl-inosito 3-kinase (PI3K) family of proteins, ataxia telangiectasia mutated (ATM), DNA-protein kinase catalytic subunit and ATM and RAD3-related (ATR). The phosphorylated form of H2AX, referred to as gammaH2AX, spreads to adjacent regions of chromatin from the site of the DSB, forming discrete foci, which are easily visualized by immunofluorescence microscopy. Analysis and quantitation of gammaH2AX foci has been widely used to evaluate DSB formation and repair, particularly in response to ionizing radiation and for evaluating the efficacy of various radiation modifying compounds and cytotoxic compounds. Given the exquisite specificity and sensitivity of this de novo marker of DSBs, it has provided new insights into the processes of DNA damage and repair in the context of chromatin. For example, in radiation biology the central paradigm is that the nuclear DNA is the critical target with respect to radiation sensitivity. Indeed, the general consensus in the field has largely been to view chromatin as a homogeneous template for DNA damage and repair. However, with the use of gammaH2AX as molecular marker of DSBs, a disparity in gamma-irradiation-induced gammaH2AX foci formation in euchromatin and heterochromatin has been observed. Recently, we used a panel of antibodies to either mono-, di- or tri- methylated histone H3 at lysine 9 (H3K9me1, H3K9me2, H3K9me3) which are epigenetic imprints of constitutive heterochromatin and transcriptional silencing and lysine 4 (H3K4me1, H3K4me2, H3K4me3), which are tightly correlated actively transcribing euchromatic regions, to investigate the spatial distribution of gammaH2AX following ionizing radiation. In accordance with the prevailing ideas regarding chromatin biology, our findings indicated a close correlation between gammaH2AX formation and active transcription. Here we demonstrate our immunofluorescence method for detection and quantitation of gammaH2AX foci in non-adherent cells, with a particular focus on co-localization with other epigenetic markers, image analysis and 3D-modeling. PMID:20736911

Vasireddy, Raja S; Tang, Michelle M; Mah, Li-Jeen; Georgiadis, George T; El-Osta, Assam; Karagiannis, Tom C

2010-01-01

121

The origin of the diffuse background gamma radiation  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

122

The origin of the diffuse background gamma-radiation  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

123

Gamma-ray lines from radiative dark matter decay  

SciTech Connect

The decay of dark matter particles which are coupled predominantly to charged leptons has been proposed as a possible origin of excess high-energy positrons and electrons observed by cosmic-ray telescopes PAMELA and Fermi LAT. Even though the dark matter itself is electrically neutral, the tree-level decay of dark matter into charged lepton pairs will generically induce radiative two-body decays of dark matter at the quantum level. Using an effective theory of leptophilic dark matter decay, we calculate the rates of radiative two-body decays for scalar and fermionic dark matter particles. Due to the absence of astrophysical sources of monochromatic gamma rays, the observation of a line in the diffuse gamma-ray spectrum would constitute a strong indication of a particle physics origin of these photons. We estimate the intensity of the gamma-ray line that may be present in the energy range of a few TeV if the dark matter decay interpretation of the leptonic cosmic-ray anomalies is correct and comment on observational prospects of present and future Imaging Cherenkov Telescopes, in particular the CTA.

Garny, Mathias; Ibarra, Alejandro; Tran, David [Physik-Department T30d, Technische Universität München, James-Franck-Straße, 85748 Garching (Germany); Weniger, Christoph, E-mail: mathias.garny@ph.tum.de, E-mail: alejandro.ibarra@ph.tum.de, E-mail: david.tran@ph.tum.de, E-mail: weniger@mppmu.mpg.de [Max-Planck-Institut für Physik, München, Föhringer Ring 6, 80805 München (Germany)

2011-01-01

124

Current Trends in Gamma Radiation Detection for Radiological Emergency Response  

SciTech Connect

Passive and active detection of gamma rays from shielded radioactive materials, including special nuclear materials, is an important task for any radiological emergency response organization. This article reports on the current trends and status of gamma radiation detection objectives and measurement techniques as applied to nonproliferation and radiological emergencies. In recent years, since the establishment of the Domestic Nuclear Detection Office by the Department of Homeland Security, a tremendous amount of progress has been made in detection materials (scintillators, semiconductors), imaging techniques (Compton imaging, use of active masking and hybrid imaging), data acquisition systems with digital signal processing, field programmable gate arrays and embedded isotopic analysis software (viz. gamma detector response and analysis software [GADRAS]1), fast template matching, and data fusion (merging radiological data with geo-referenced maps, digital imagery to provide better situational awareness). In this stride to progress, a significant amount of interdisciplinary research and development has taken place–techniques and spin-offs from medical science (such as x-ray radiography and tomography), materials engineering (systematic planned studies on scintillators to optimize several qualities of a good scintillator, nanoparticle applications, quantum dots, and photonic crystals, just to name a few). No trend analysis of radiation detection systems would be complete without mentioning the unprecedented strategic position taken by the National Nuclear Security Administration (NNSA) to deter, detect, and interdict illicit trafficking in nuclear and other radioactive materials across international borders and through the global maritime transportation–the so-called second line of defense.

Mukhopadhyay, S., Guss, P., Maurer, R.

2011-09-01

125

Cell Phone RF Radiation  

NASA Astrophysics Data System (ADS)

In a recent article in Physics Today, Meredith and Redish emphasized the need to make introductory physics courses beneficial for life sciences majors.1 In this study, a lab activity is proposed to measure the intensity of electromagnetic waves emitted by cell phones and connect these measurements to various standards, biological topics, and personal health.

Abdul-Razzaq, Wathiq

2015-04-01

126

Gamma-ray pulsars: Radiation processes in the outer magnetosphere  

NASA Technical Reports Server (NTRS)

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.

Romani, Roger W.

1996-01-01

127

Effect of gamma radiation on the survival of fungal and actinomycetal florae contaminating medicinal plants  

Microsoft Academic Search

This study evaluates the effect of gamma radiation on the viability of fungi and actinomycetes that contaminate medicinal plants. The relationship between the total lipids of some fungi and actinomycetes and their sensitivity to gamma radiation is also investigated. The data reveal that the viable counts of these florae decrease approximately exponentially with the radiation dose, the effective dose for

Nagy H. Aziz; M. Z. El-Fouly; M. R. Abu-Shady; L. A. A. Moussa

1997-01-01

128

Gamma-Radiation Background Onboard Russian Orbital Stations  

NASA Astrophysics Data System (ADS)

Large manned space flight missions have several advantages for carrying out astrophysical and cosmic ray experiments, including the ability to install heavy instruments with large dimensions, increased electrical power and telemetry capacity, and the operation of fixed instruments by qualified personnel (astronauts). The main disadvantage in the use of heavy orbital stations for these experiments is the high level of background radiation generated by the interaction of station material with primary cosmic rays, high energy particles that exist in the magnetosphere of Earth, and albedo radiation from Earth. In some cases, additional radiation may originate from man-made radiation sources installed at the stations. For many years MEPhI have maintained experiments onboard manned Russian space flight missions to study primary gamma-rays at two energy intervals: 0.1 - 8 MeV and 30-600 MeV and electrons with energy more than 30 MeV. During these experiments significant time was spent investigating high energy background radiation onboard the stations. To measure 30-600 MeV gamma-rays, the gas-Cherenkov-scintillation telescope Elena was used. The angular view of this telescope was 10 deg, with a geometrical factor of 0.5 cm2sr. This telescope was operated onboard the orbital stations Salyut-6 and Salyut-7. Usually these stations were operated together with the space missions Soyuz and Progress. For background measurements, cosmonauts installed the telescope at various locations on Salyut, Soyuz and Progress, and oriented it in various directions respectively to the station's axes. During these experiments, the orbital stations were not oriented.

Dmitrenko, V. V.; Galper, A. M.; Gratchev, V. M.; Kirillov-Ugryumov, V. G.; Krivov, S. V.; Moiseev, A. A.; Ulin, S. E.; Uteshev, Z. M.; Vlasik, K. F.; Yurkin, Yn. T.

129

Carnosine mitigates apoptosis and protects testicular seminiferous tubules from gamma-radiation-induced injury in mice.  

PubMed

This study investigated the radioprotective effects of a naturally occurring dipeptide, carnosine, on testicular damage. Carnosine was administered (10, 50 and 100 mg kg(-1) body weight) to male mice via intraperitoneal injection for 4 days prior to gamma irradiation (2 Gy). Apoptosis with the TUNEL assay and histopathological parameters were evaluated 12-h and 14-day post-irradiation. Pre-treatment with carnosine before irradiation significantly reduced the frequency of TUNEL-positive cells induced by radiation treatment at all doses by reduction factors of 1.8, 2.47 and 2.23 for carnosine at 10, 50 and 100 mg kg(-1) bw, respectively, unlike that observed in the radiation alone group. Exposure to ionising radiation decreased sperm count and reduced the height and diameter of seminiferous epithelial tubules. Pre-treatment with all doses of carnosine significantly augmented seminiferous epithelial height and tubule diameter and also increased the number of germinal cells in comparison to the group treated with radiation only. These results indicate that carnosine prevents testicular dysfunction induced by gamma-irradiation via an anti-apoptotic effect; this restoration of proper testicular function ultimately leads to the recovery of spermatogenesis. PMID:24215656

Haeri, S A; Rajabi, H; Fazelipour, S; Hosseinimehr, S J

2014-11-01

130

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

SciTech Connect

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.

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

131

Ceramic Matrix Composites Performances Under High Gamma Radiation Doses  

NASA Astrophysics Data System (ADS)

Ceramic matrix composites reinforced by continuous ceramic fibers (CMCs) represent a class of advanced materials developed for applications in automotive, aerospace, nuclear fusion reactors and in other specific systems for harsh environments. In the present work, the silicon carbide/silicon carbide (SiCf/SiC) composites, manufactured by Chemical Vapour Infiltration process at FN S.p.A. plant, have been evaluated in term of gamma radiation hardness at three different absorbed doses (up to around 3MGy). Samples behavior has been investigated before and after irradiation by means of mechanical tests (flexural strength) and by surface and structural analyses (X-ray diffraction, SEM, FTIR-ATR, EPR).

Cemmi, A.; Baccaro, S.; Fiore, S.; Gislon, P.; Serra, E.; Fassina, S.; Ferrari, E.; Ghisolfi, E.

2014-06-01

132

Natural Radiation from Soil using Gamma-Ray Spectrometry  

NASA Astrophysics Data System (ADS)

We have studied the distribution of natural radioactivity in the soil of Interlagos, in São Paulo city and Billings Reservoir, in São Bernardo do Campo, São Paulo, Brazil. The main contribution of the effective radiation dose is due to the elements of the 238Th decay series, with smaller contributions from 40K and the elements of the series of 238U. 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.

Silveira, M. A. G.; Moreira, R. H.; de Paula, A. L. C.; Medina, N. H.

2009-06-01

133

Heavy ion radiative capture: 12C(12C,{gamma})  

SciTech Connect

The heavy ion radiative capture reaction 12C(12C,{gamma}) has been investigated around a beam energy of 16 MeV. The total cross-section has been measured with the Fragment Mass Analyser at Argonne National Laboratory and found to be somewhat larger than has previously been measured. A subsequent measurement with the Gammasphere array has shown that a considerable proportion of this extra cross-section relates to a highly non-statistical decay through high-lying states in 24Mg.

Jenkins, D.G.; Fulton, B.R.; Pearson, J. [Department of Physics, University of York, York, YO10 5DD (United Kingdom); Lister, C.J.; Carpenter, M.P.; Freeman, S.; Hammond, N.; Janssens, R.V.F.; Khoo, T.L.; Lauritsen, T.; Moore, E.F.; Wuosmaa, A.H. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Fallon, P.; Goergen, A.; Macchiavelli, A.O.; McMahan, M. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720 (United States); Freer, M. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Haas, F. [IReS, Centre National de la Recherche Scientifique, F-67037 Strasbourg Cedex 2 (France)

2004-02-27

134

Combined Treatment With Peroxisome Proliferator-Activated Receptor (PPAR) Gamma Ligands and Gamma Radiation Induces Apoptosis by PPAR?-Independent Up-Regulation of Reactive Oxygen Species-Induced Deoxyribonucleic Acid Damage Signals in Non-Small Cell Lung Cancer Cells  

SciTech Connect

Purpose: To investigate possible radiosensitizing activities of the well-known peroxisome proliferator-activated receptor (PPAR)? ligand ciglitazone and novel PPAR? ligands CAY10415 and CAY10506 in non-small cell lung cancer (NSCLC) cells. Methods and Materials: Radiosensitivity was assessed using a clonogenic cell survival assay. To investigate the mechanism underlying PPAR? ligand-induced radiosensitization, the subdiploid cellular DNA fraction was analyzed by flow cytometry. Activation of the caspase pathway by combined PPAR? ligands and ?-radiation treatment was detected by immunoblot analysis. Reactive oxygen species (ROS) were measured using 2,7-dichlorodihydrofluorescein diacetate and flow cytometry. Results: The 3 PPAR? ligands induced cell death and ROS generation in a PPAR?-independent manner, enhanced ?-radiation–induced apoptosis and caspase-3–mediated poly (ADP-ribose) polymerase (PARP) cleavage in vitro. The combined PPAR? ligand/?-radiation treatment triggered caspase-8 activation, and this initiator caspase played an important role in the combination-induced apoptosis. Peroxisome proliferator-activated receptor-? ligands may enhance the ?-radiation-induced DNA damage response, possibly by increasing ?-H2AX expression. Moreover, the combination treatment significantly increased ROS generation, and the ROS scavenger N-acetylcysteine inhibited the combined treatment-induced ROS generation and apoptotic cell death. Conclusions: Taken together, these results indicated that the combined treatment of PPAR? ligands and ?-radiation synergistically induced DNA damage and apoptosis, which was regulated by ROS.

Han, Eun Jong; Im, Chang-Nim; Park, Seon Hwa [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)] [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Moon, Eun-Yi [Department of Bioscience and Biotechnology, Sejong University, Seoul (Korea, Republic of)] [Department of Bioscience and Biotechnology, Sejong University, Seoul (Korea, Republic of); Hong, Sung Hee, E-mail: gobrian@kcch.re.kr [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

2013-04-01

135

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

PubMed Central

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

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

2010-01-01

136

Gamma radiation effects on commercial Mexican bread making wheat flour  

NASA Astrophysics Data System (ADS)

Gamma irradiation is considered to be an alternative method for food preservation to prevent food spoilage, insect infestation and capable of reducing the microbial load. In the present investigation, commercial Mexican bread making wheat flour was irradiated at 1.0 kGy using a 60C Gammabeam 651 PT irradiator facility. No changes were detected in moisture, protein and ashes in gamma irradiated samples as compared to those of non-irradiated samples. Slight radiation effects were observed in the alveogram values and farinograph properties; the falling number decreased 11%, the absorption as well as the mixing tolerance were practically unchanged by irradiation. An increase of 15% in the stability value and a 29% in the dough development time were observed. Also the deformation energy decreased 7% with no change at all in the tenacity/extensibility factor. Total aerobic, yeast and mold counts were reduced 96%, 25% and 75%; respectively by the irradiation process. The obtained results confirm that gamma irradiation is effective in reducing the microbial load in bread making wheat flour without a significant change in the physicochemical and baking properties.

Agúndez-Arvizu, Z.; Fernández-Ramírez, M. V.; Arce-Corrales, M. E.; Cruz-Zaragoza, E.; Meléndrez, R.; Chernov, V.; Barboza-Flores, M.

2006-04-01

137

Uv- and Gamma-Radiation Sensitive Mutants of Arabidopsis Thaliana  

PubMed Central

Arabidopsis seedlings repair UV-induced DNA damage via light-dependent and -independent pathways. The mechanism of the ``dark repair'' pathway is still unknown. To determine the number of genes required for dark repair and to investigate the substrate-specificity of this process we isolated mutants with enhanced sensitivity to UV radiation in the absence of photoreactivating light. Seven independently derived UV sensitive mutants were isolated from an EMS-mutagenized population. These fell into six complementation groups, two of which (UVR1 and UVH1) have previously been defined. Four of these mutants are defective in the dark repair of UV-induced pyrimidine [6-4] pyrimidinone dimers. These four mutant lines are sensitive to the growth-inhibitory effects of gamma radiation, suggesting that this repair pathway is also involved in the repair of some type of gamma-induced DNA damage product. The requirement for the coordinate action of several different gene products for effective repair of pyrimidine dimers, as well as the nonspecific nature of the repair activity, is consistent with nucleotide excision repair mechanisms previously described in Saccharomyces cerevisiae and nonplant higher eukaryotes and inconsistent with substrate-specific base excision repair mechanisms found in some bacteria, bacteriophage, and fungi. PMID:9383080

Jiang, C. Z.; Yen, C. N.; Cronin, K.; Mitchell, D.; Britt, A. B.

1997-01-01

138

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

PubMed

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

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

2014-11-01

139

Combination of {gamma}-radiation antagonizes the cytotoxic effects of vincristine and vinblastine on both mitotic arrest and apoptosis  

SciTech Connect

Purpose: Combination therapy with different modalities is a common practice in the treatment of cancer. The promising clinical profile of vincristine and vinblastine has promoted considerable interest in combining these vinca alkaloids with radiation therapy to treat a variety of solid tumors. However, the therapeutic efficacy and the interaction between the vinca alkaloids with radiation is not entirely clear. In this study, we assessed the potential interactions in the combination of vincristine or vinblastine with {gamma}-radiation against human tumor cells in vitro. Methods and materials: Vincristine or vinblastine and {gamma}-radiation were administrated at three different sequences designed as preradiated, coradiated, and postradiated combinations in human breast cancer cells and human epidermoid carcinoma cells. The cytotoxic interactions and mutual influences between these two modalities were analyzed by a series of assays including cytotoxic, morphologic, and biochemical examinations. Results: Our results showed that the combination of these two modalities did not produce any synergistic or additive effects. Instead, the clonogenic assays showed the survival rates of these combinations were increased up to 2.17-fold and 2.7-fold, respectively, of those treated with vincristine or vinblastine alone (p < 0.01). DNA fragmentation, T{alpha}T-mediated dUTP nick end labeling (TUNEL) assay, and flow cytometric assays also showed that the combination of {gamma}-radiation significantly interfered with the ability of these vinca alkaloids to induce apoptosis. Further analyses indicated that addition of {gamma}-radiation resulted in cell cycle arrest at the G{sub 2} phase, which subsequently prevented the mitotic arrest induced by vincristine or vinblastine. In addition, biochemical examinations revealed that {gamma}-radiation regulated p34{sup cdc2}/cyclin B1 and survivin, and inhibited I{kappa}B{alpha} degradation and bcl-2 phosphorylation. Conclusions: These results suggest that {gamma}-radiation might specifically block the cell cycle at the G{sub 2} phase, which in turn interferes with the cytotoxic effects of vincristine or vinblastine on mitotic arrest and apoptosis. Thereby, it eventually results in an antagonistic interaction between these two modalities. This finding may be implicated in the clinical application of combination therapy of vinca alkaloids and radiation.

Sui, Meihua [Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC (United States); Fan Weimin [Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC (United States)]. E-mail: fanw@musc.edu

2005-03-15

140

Oxidative stress and gamma radiation-induced cancellous bone loss with musculoskeletal disuse  

PubMed Central

Exposure of astronauts in space to radiation during weightlessness may contribute to subsequent bone loss. Gamma irradiation of postpubertal mice rapidly increases the number of bone-resorbing osteoclasts and causes bone loss in cancellous tissue; similar changes occur in skeletal diseases associated with oxidative stress. Therefore, we hypothesized that increased oxidative stress mediates radiation-induced bone loss and that musculoskeletal disuse changes the sensitivity of cancellous tissue to radiation exposure. Musculoskeletal disuse by hindlimb unloading (1 or 2 wk) or total body gamma irradiation (1 or 2 Gy of 137Cs) of 4-mo-old, male C57BL/6 mice each decreased cancellous bone volume fraction in the proximal tibiae and lumbar vertebrae. The extent of radiation-induced acute cancellous bone loss in tibiae and lumbar vertebrae was similar in normally loaded and hindlimb-unloaded mice. Similarly, osteoclast surface in the tibiae increased 46% as a result of irradiation, 47% as a result of hindlimb unloading, and 64% as a result of irradiation + hindlimb unloading compared with normally loaded mice. Irradiation, but not hindlimb unloading, reduced viability and increased apoptosis of marrow cells and caused oxidative damage to lipids within mineralized tissue. Irradiation also stimulated generation of reactive oxygen species in marrow cells. Furthermore, injection of ?-lipoic acid, an antioxidant, mitigated the acute bone loss caused by irradiation. Together, these results showed that disuse and gamma irradiation, alone or in combination, caused a similar degree of acute cancellous bone loss and shared a common cellular mechanism of increased bone resorption. Furthermore, irradiation, but not disuse, may increase the number of osteoclasts and the extent of acute bone loss via increased reactive oxygen species production and ensuing oxidative damage, implying different molecular mechanisms. The finding that ?-lipoic acid protected cancellous tissue from the detrimental effects of irradiation has potential relevance to astronauts and radiotherapy patients. PMID:19875718

Kondo, Hisataka; Yumoto, Kenji; Alwood, Joshua S.; Mojarrab, Rose; Wang, Angela; Almeida, Eduardo A. C.; Searby, Nancy D.; Limoli, Charles L.

2010-01-01

141

Modeling radiation-induced cell cycle delays  

Microsoft Academic Search

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

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

2009-01-01

142

gamma-radiation-induced gammaH2AX formation occurs preferentially in actively transcribing euchromatic loci.  

PubMed

The central dogma in radiation biology is that nuclear DNA is the critical target with respect to radiosensitivity. In accordance with the theoretical expectations, and in the absence of a conclusive model, the general consensus in the field has been to view chromatin as a homogeneous template for DNA damage and repair. This paradigm has been called into question by recent findings indicating a disparity in gamma-irradiation-induced gammaH2AX foci formation in euchromatin and heterochromatin. Here, we have extended those studies and provide evidence that gammaH2AX foci form preferentially in actively transcribing euchromatin following gamma-irradiation. PMID:19859659

Vasireddy, Raja S; Karagiannis, Tom C; El-Osta, Assam

2010-01-01

143

GaAs Solar Cell Radiation Handbook  

NASA Technical Reports Server (NTRS)

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.

Anspaugh, B. E.

1996-01-01

144

Modeling Gamma-Radiation from Thunderclouds and Lightning  

NASA Astrophysics Data System (ADS)

Terrestrial gamma-ray flashes are sub-millisecond bursts of energetic radiation originating from thunderclouds in the earth's atmosphere [e.g., Fishman et al., Science, 264, 1313, 1994; Dwyer et al., Space Sci. Rev., 10.1007/s11214-012-9894-0, 2012]. Recent analysis of TGF observations and lightning radio emission indicates that the production of TGFs is normally associated with the initial lightning leader development inside thunderclouds [e.g., Shao et al., J. Geophys. Res., 115, A00E30, 2010; Lu et al., Geophys. Res. Lett., 37, L11806, 2010; Cummer et al., Geophys. Res. Lett., 38, L14810, 2011]. In addition to relatively short TGFs, thunderclouds and lightning can also make minute long gamma-ray glows according to ground-based [e.g., Chilingarian et al., Phys. Rev. D, 82, 043009, 2010] and airborne measurements [e.g., Smith et al., J. Geophys. Res., 116, D20124, 2011]. A viable theory for explaining the gamma-ray production by thunderclouds and lightning is the relativistic feedback discharge mechanism introduced by Dwyer [Geophys. Res. Lett., 30, 2055, 2003]. A comprehensive modeling study of TGFs based on this theory was recently reported in [Dwyer, J. Geophys. Res., 117, A02308, 2012], where many observed TGF aspects were successfully reproduced. In this talk, we report simulation results from a new TGF modeling code developed at Florida Tech that implements the same model as the work of Dwyer [2012]. The code is built on a streamer code that has been used for studying streamer discharges in sprites, lightning and laboratory experiments [e.g., Liu and Pasko, J. Geophys. Res., 109, A04301, 2004]. Components for modeling the transport of runaway electrons and positrons, the feedback process, the gamma-ray production, and the lightning leader propagation have been added. The new code can fully model transport of low energy electrons and ions, ionization, attachment, and recombination. Several simulation cases are reported, showing how single and multiple pulsed TGFs can be produced. Finally, we compare the present work with the gamma-ray observations and the modeling study by Dwyer [2012].

Liu, N.; Dwyer, J. R.

2012-12-01

145

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

146

Ionizing radiation sensitizes bone cells to apoptosis  

Microsoft Academic Search

Osteoradionecrosis is a common sequelae of radiation therapy for head and neck cancer. To test the hypothesis that radiation induces osteoradionecrosis by induction of bone cell apoptosis, we exposed MC3T3-E1 osteoblast-like cells to ?-radiation and evaluated cell viability. Twenty-four hours postirradiation, measurement of osteoblast dehydrogenase activity suggested that there was a small decrease in cell viability. However, TUNEL and flow

K. H Szymczyk; I. M Shapiro; C. S Adams

2004-01-01

147

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

PubMed Central

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

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

2014-01-01

148

Population doses from environmental gamma radiation in Iraq  

SciTech Connect

The exposure rates due to external gamma radiation were measured in 11 Iraqi governerates. Measurements were performed with an Environmental Monitoring System (RSS-111) in open air 1 m above the ground. The average absorbed dose rate in each governerate was as follows (number x 10(-2) microGy h-1): Babylon (6.0), Kerbala (5.3), Al-Najaf (5.4), Al-Kadysia (6.5), Wasit (6.5), Diala (6.5), Al-Anbar (6.5), Al-Muthana (6.6), Maisan (6.8), Thee-Kar (6.6), and Al-Basrah (6.5). The collective doses to the population living in these governerates were 499, 187, 239, 269, 262, 458, 384, 153, 250, 450, and 419 person-Sv, respectively.

Marouf, B.A.; Mohamad, A.S.; Taha, J.S.; al-Haddad, I.K. (Iraq Atomic Energy Commission, Nuclear Research Center, Tuwaitha, Baghdad, (Iraq))

1992-05-01

149

Dose-dependent hepatic transcriptional responses in Atlantic salmon (Salmo salar) exposed to sublethal doses of gamma radiation.  

PubMed

Due to the production of free radicals, gamma radiation may pose a hazard to living organisms. The high-dose radiation effects have been extensively studied, whereas the ecotoxicity data on low-dose gamma radiation is still limited. The present study was therefore performed using Atlantic salmon (Salmo salar) to characterize effects of low-dose (15, 70 and 280 mGy) gamma radiation after short-term (48h) exposure. Global transcriptional changes were studied using a combination of high-density oligonucleotide microarrays and quantitative real-time reverse transcription polymerase chain reaction (qPCR). Differentially expressed genes (DEGs; in this article the phrase gene expression is taken as a synonym of gene transcription, although it is acknowledged that gene expression can also be regulated, e.g., at protein stability and translational level) were determined and linked to their biological meanings predicted using both Gene Ontology (GO) and mammalian ortholog-based functional analyses. The plasma glucose level was also measured as a general stress biomarker at the organism level. Results from the microarray analysis revealed a dose-dependent pattern of global transcriptional responses, with 222, 495 and 909 DEGs regulated by 15, 70 and 280 mGy gamma radiation, respectively. Among these DEGs, only 34 were commonly regulated by all radiation doses, whereas the majority of differences were dose-specific. No GO functions were identified at low or medium doses, but repression of DEGs associated with GO functions such as DNA replication, cell cycle regulation and response to reactive oxygen species (ROS) were observed after 280mGy gamma exposure. Ortholog-based toxicity pathway analysis further showed that 15mGy radiation affected DEGs associated with cellular signaling and immune response; 70mGy radiation affected cell cycle regulation and DNA damage repair, cellular energy production; and 280mGy radiation affected pathways related to cell cycle regulation and DNA repair, mitochondrial dysfunction and immune functions. Twelve genes representative of key pathways found in this study were verified by qPCR. Potential common MoAs of low-dose gamma radiation may include induction of oxidative stress, DNA damage and disturbance of oxidative phosphorylation (OXPHOS). Although common MoAs were proposed, a number of DEGs and pathways were still found to be dose-specific, potentially indicating multiple mechanisms of action (MOAs) of low-dose gamma radiation in fish. In addition, plasma glucose displayed an apparent increase with increasing radiation doses, although the results were not significantly different from the control. These findings suggested that sublethal doses of gamma radiation may cause dose-dependent transcriptional changes in the liver of Atlantic salmon after short-term exposure. The current study predicted multiple MoA for gamma radiation and may aid future impact assessment of environmental radioactivity in fish. PMID:25146236

Song, You; Salbu, Brit; Teien, Hans-Christian; Heier, Lene Sørlie; Rosseland, Bjørn Olav; Tollefsen, Knut Erik

2014-11-01

150

\\Gamma\\Gamma \\Gamma\\Gamma  

E-print Network

\\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

Laske, Gabi

151

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

PubMed Central

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

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

2014-01-01

152

Lycopene protects the structure of the small intestine against gamma-radiation-induced oxidative stress.  

PubMed

The small intestine displays numerous morphological and functional alterations after exposure to ionizing radiations. Oxidative stress and changes in monoamines levels may contribute toward some of these alterations. The objective of the current work is to evaluate the efficacy of lycopene on radiation-induced damage in the small intestine. Lycopene (5 mg/kg BW) was given to male albino rats, via gavages for 7 days before whole body exposure to gamma ray (6 Gy). Irradiated animals, sacrificed 7 days after irradiation, showed sloughing villi, ulcers, and ruptured goblet cells, shrinkage of submucosa layers, more fibers and fibroblasts. Histopathological changes were associated with a significant increase in thiobarbituric acid reactive substances (TBARS) and alteration in xanthine oxidoreductase system (XOR). In parallel, significant decreases in reduced glutathione (GSH) content, superoxide dismutase (SOD) and catalase (CAT) activities were recorded. Gamma irradiation has also induced a significant decrease in the level of monoamines: serotonin (5-HT), dopamine (DA), norepinephrine (NE), and epinephrine (EPI) associated with an increase in monoamine-oxidase (MAO) activity. Lycopene pretreatment has significantly improved the oxidant/antioxidant status, which was associated with significant regeneration of the small intestine, and improved monoamines levels. Based on these results, it is concluded that lycopene may protect the small intestine against radiation-induced damage. PMID:20041432

Saada, Helen N; Rezk, Renée G; Eltahawy, Noaman A

2010-06-01

153

Mediate gamma radiation effects on some packaged food items  

NASA Astrophysics Data System (ADS)

For most of prepackaged foods a 10 kGy radiation dose is considered the maximum dose needed; however, the commercially available and practically accepted packaging materials must be suitable for such application. This work describes the application of ionizing radiation on several packaged food items, using 5 dehydrated food items, 5 ready-to-eat meals and 5 ready-to-eat food items irradiated in a 60Co gamma source with a 3 kGy dose. The quality evaluation of the irradiated samples was performed 2 and 8 months after irradiation. Microbiological analysis (bacteria, fungus and yeast load) was performed. The sensory characteristics were established for appearance, aroma, texture and flavor attributes were also established. From these data, the acceptability of all irradiated items was obtained. All ready-to-eat food items assayed like manioc flour, some pâtés and blocks of raw brown sugar and most of ready-to-eat meals like sausages and chicken with legumes were considered acceptable for microbial and sensory characteristics. On the other hand, the dehydrated food items chosen for this study, such as dehydrated bacon potatoes or pea soups were not accepted by the sensory analysis. A careful dose choice and special irradiation conditions must be used in order to achieve sensory acceptability needed for the commercialization of specific irradiated food items.

Inamura, Patricia Y.; Uehara, Vanessa B.; Teixeira, Christian A. H. M.; del Mastro, Nelida L.

2012-08-01

154

JITTER RADIATION MODEL OF THE CRAB GAMMA-RAY FLARES  

SciTech Connect

The gamma-ray flares of the Crab nebula detected by the Fermi and AGILE satellites challenge our understanding of the physics of pulsars and their nebulae. The central problem is that the peak energy of the flares exceeds the maximum energy E {sub c} determined by synchrotron radiation loss. However, when turbulent magnetic fields exist with scales {lambda}{sub B} smaller than 2{pi}mc {sup 2}/eB, jitter radiation can emit photons with energies higher than E {sub c}. The scale required for the Crab flares is about two orders of magnitude less than the wavelength of the striped wind. We discuss a model in which the flares are triggered by plunging the high-density blobs into the termination shock. The observed hard spectral shape may be explained by the jitter mechanism. We make three observational predictions: first, the polarization degree will become lower in flares; second, no counterpart will be seen in TeV-PeV range; and third, the flare spectrum will not be harder than {nu}F {sub {nu}}{proportional_to}{nu}{sup 1}.

Teraki, Yuto; Takahara, Fumio, E-mail: teraki@vega.ess.sci.osaka-u.ac.jp [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)] [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)

2013-02-15

155

The effect of gamma radiation on the ultrastructure of sweet potatoes (Ipomoea batatas)  

SciTech Connect

Radiation is being used to increase the storage life of fresh foods. Various doses of gamma radiation were administered to Jewel cultivar sweet potatoes and the effects were monitored by direct observation and by scanning and transmission electron microscopy. Potatoes were divided into two groups: those irradiated immediately after harvest (doses = 0 kGy - 0.4 KGy) and those irradiated one week after harvest (doses = 0 kGy - 0.4 kGy). Potatoes were examined and viewed each month for 7 months. Gross observations included weight, color and texture of the sweet potatoes. Those potatoes irradiated immediately after harvest spoiled faster than those irradiated one week after harvest. Scanning electron microscopy demonstrated several cellular modifications accompanying spoilage. Cell collapse was greatest at the higher radiation doses during the periods of 1 to 5 months post-irradiation. The shape and size of starch granules varied with storage time and radiation levels. The mitochondria, cell walls and plasma membranes appeared normal as seen by transmission electron microscopy until 6 months post-irradiation for potatoes irradiated both immediately after harvest and one week after harvest. Thereafter, degradative changes were observed.

Brown, A.

1986-12-01

156

Autologous Adipocyte Derived Stem Cells Favour Healing in a Minipig Model of Cutaneous Radiation Syndrome  

Microsoft Academic Search

Cutaneous radiation syndrome (CRS) is the delayed consequence of localized skin exposure to high doses of ionizing radiation. Here we examined for the first time in a large animal model the therapeutic potential of autologous adipose tissue-derived stroma cells (ASCs). For experiments, Göttingen minipigs were locally gamma irradiated using a 60Co source at the dose of 50 Gy and grafted

Fabien Forcheron; Diane Agay; Harry Scherthan; Diane Riccobono; Francis Herodin; Viktor Meineke; Michel Drouet

2012-01-01

157

Progenitors Mobilized by Gamma-Tocotrienol as an Effective Radiation Countermeasure  

PubMed Central

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

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

158

Intestinal endocrine cells in radiation enteritis  

SciTech Connect

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.

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

1989-08-01

159

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

Microsoft Academic Search

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

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

1991-01-01

160

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

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.

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

161

Airborne gamma-radiation survey of the Jabel Ishmas Quadrangle, Kingdom of Saudi Arabia  

USGS Publications Warehouse

An airborne gamma-radiation survey system, which includes digital recording and automatic data processing procedures developed by the U. S. Geological Survey Saudi Arabian Project, is used to collect spectral gamma-radiation data as an aid to regional geologic mapping of pediment areas on the Arabian Shield. The areal extent of rock units can generally be distinguished by the intensity of their radiation pattern. Rocks of ultramafic composition have low radiation response, whereas more felsic rocks reflect higher radiation response. Interpretations based on radiometric data enable the geologist to gain some understanding about the geologic setting of an area before he begins field mapping.

Flanigan, Vincent J.

1975-01-01

162

THERMAL RADIATION FROM GAMMA-RAY BURST JETS  

SciTech Connect

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 photosphere. For an on-axis observer, the photosphere appears concave due to the low density and high beaming factor of the jet. The luminosity varies because of the abrupt change in the position of the photosphere due to the internal structure of the jet. Comparing our results with GRB 090902B, the flux level of the thermal-like component is similar to our model, although the peak energy appears slightly higher (but still within a factor of two). From the comparison, we estimate that the bulk Lorentz factor of GRB 090902B is {Gamma} {approx} 2.4 x 10{sup 2}(r/10{sup 12} cm), where r is the radius of the photosphere. The spectrum for an on-axis observer is harder than that for an off-axis observer. There is a time lag of a few seconds for high energy bands in the light curve. This may be the reason for the delayed onset of GeV emission seen in GRB 080916C. The spectrum below the peak energy is a power law and the index is 2.3-2.6, which is softer than that of a single temperature Planck distribution but still harder than that of the typical value of the observed spectrum.

Mizuta, Akira [Theory Center, Institute of Particle and Nuclear Studies, KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba 305-0801 (Japan); Nagataki, Shigehiro; Aoi, Junichi, E-mail: mizuta@post.kek.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan)

2011-05-01

163

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...

164

Repair mechanisms in radiation-induced cell transformation  

SciTech Connect

Our data with both low- and high-LET radiations are qualitatively similar to results obtained in vivo. This is evident, for example, in the reductions in cell transformation for protracted exposures of ..gamma..-rays. The consistencies between our results with cells and the data of others with animals lend support to Gray's hypothesis that tumorigenesis is the net effect of a low probability inductive process, and a high probability killing process. An important prediction can be made when spontaneous frequency is appreciable (e.g., 43% in the case of reticulum cell sarcoma in RFM mice). For small doses, tumorigenesis would drop provided that: (a) the cells responsible for the spontaneous incidence are present at the time of exposure; and (b) the progenitor cells of the tumor are not resistant to cell killing.

Elkind, M.M.; Han, A.; Hill, C.K.; Buonaguro, F.

1983-01-01

165

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

E-print Network

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

Boyer, Edmond

166

Effects of Dietary Iron and Gamma Radiation on the Rat Retina  

NASA Technical Reports Server (NTRS)

A health risk of concern for NASA relates to radiation exposure and its synergistic effects with other space environmental factors, includi ng nutritional status of the crew. Astronauts consume almost three times the recommended daily allowance of iron due to the use of fortifie d foods aboard the International Space Station, with iron intake occa sionally exceeding six times the recommended values. Recently, NASA has become concerned with visual changes associated with spaceflight, a nd research is being conducted to elucidate the etiology of eye structure alterations in the spaceflight environment. Terrestrially, iron o verload is also associated with certain optic neuropathies. In additi on, due to its role in Fenton reactions, iron can potentiate oxidative stress, which is a recognized cause of cataract formation. As part o f a study investigating the combined effects of radiation exposure an d iron overload on multiple physiological systems, we focused on defining the effects of both treatments on eye biology. In this study, 12- week-old Sprague-Dawley rats were assigned to one of four experimental groups: normal iron/no radiation (Control/Sham), high iron/no radiat ion (Fe/Sham), normal iron/gamma radiation (3 Gy cumulative dose, fra ctionated at 0.375 Gy/d every other day for 16 d) (Control/Rad), and high iron/gamma radiation (Fe/Rad). Oxidative stress-induced DNA damag e, measured as concentration of the marker 8-hydroxy-2'-deoxyguanosine (8OHdG) in eye retinal tissue by enzyme-immunoanalysis did not show significant changes among treatments. However, there was an overall i ncrease in 8OHdG immunostaining density in retina sections due to radiation exposure (P = 0.05). Increased dietary iron and radiation expos ure had an interactive effect (P = 0.02) on 8OHdG immunostaining of t he retinal ganglion cell layer with iron diet increasing the signal in the group not exposed to radiation (P = 0.05). qPCR gene expression profiling of relevant target genes indicated upregulation of ferritin light chain (P = 0.09) as a result of dietary iron but no change in e xpression of the gene for ferritin heavy chain. Immunolocalization of light chain and heavy chain of the iron storage protein ferritin showed the expected distribution in the choroid, photoreceptor layer, inn er nuclear layer and in the inner plexiform layer that corresponded t o the synaptic terminals of bipolar cells. Evidence of stress and damage in the retina was also suggested by a decrease in expression of th e survival marker Bcl2 (P = 0.01) and the protective proteins clusterin (P = 0.04) and heat shock factor 1 (Hsf1, P < 0.001), as a result o f increased dietary iron. The effect of increased iron on expression of the antioxidant enzyme heme oxygenase 1 (Hmox1) had a significant interaction with the effect of radiation (P < 0.001). In summary, the results of this study indicate that both gamma radiation exposure and a moderate increase in dietary iron can contribute to deleterious cha nges in retinal health and physiology.

Morgan, Jennifer; Marshall, Grace; Theriot, Corey A.; Chacon, Natalia; Zwart, Sara; Zanello, Susana B.

2012-01-01

167

Disinfection of the bee hive's American foulbrood by gamma radiation from Cobalt-60  

NASA Astrophysics Data System (ADS)

Gamma radiation from Cobalt-60 was used to sterilize honeybee combs contaminated by Bacilluslarvae. The determination of the radiosensibility (D 10) was done on cultured cells in Brain Heart Infusion broth and was found to be determined at 125 Gy. The D 10 of isolated spores from contaminated combs was then determined at 0,518 kGy and the D 10 of spores irradiated in their own original environment was found at 2,05 kGy. These treated combs were then sent back in the beehives. The bees cleaned the combs thouroughly and started the storage of honey in some cells. Eggs were also layed in others. Forty five days later, there were still no sign of re-appearance of the American Foulbrood disease.

Gosselin, P.; Charbonneau, R.

168

Effect of gamma radiation on Aspergillus flavus and Aspergillus ochraceus ultrastructure and mycotoxin production  

NASA Astrophysics Data System (ADS)

The aim of this work was to study the effect of gamma radiation (2 kGy) on Aspergillus flavus and Aspergillus ochraceus ultrastructure. Moreover, the influence on aflatoxin B 1 and ochratoxin A production was also observed. Irradiated A. flavus strain showed a dull orangish colony while control strain showed the typical green color. Minor differences were observed on stipes, metulae and conidia size between control and irradiated A. flavus and A. ochraceus strains. Irradiated fungi showed ultrastructural changes on cell wall, plasmalema and cytoplasm levels. The levels of mycotoxins produced by irradiated strains were two times greater than those produced by control strains. Successive transferences of irradiated strains on malt extract agar allowed the fungus to recuperate morphological characteristics. Although minor changes in the fungal morphology were observed, ultrastructural changes at cell wall level and the increase of mycotoxin production ability were observed. Inappropriate storage of irradiated food and feed would allow the development of potentially more toxicogenic fungal propagules.

Ribeiro, J.; Cavaglieri, L.; Vital, H.; Cristofolini, A.; Merkis, C.; Astoreca, A.; Orlando, J.; Carú, M.; Dalcero, A.; Rosa, C. A. R.

2011-05-01

169

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

PubMed Central

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

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

2014-01-01

170

Gamma Ray Telescope Senses High-Energy Radiation  

NSDL National Science Digital Library

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.

WNET

2011-11-02

171

Evidence for a Solar Influence on Gamma Radiation from Radon  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

172

THE YIELD OF $gamma$RAY RADIATIVE CAPTURE FROM IRON  

Microsoft Academic Search

A method of measurement is reported for the determination of the yield ; of capture gamma rays from the surface of the iron shield of a neutron reactor by ; a single-crystal scintillation gamma spectrometer. The results of these ; measurements on the capture gamma rays of iron were normalized to an energy of ; 7.5 Mev over the range

A. T. Bakov; S. P. Belov; U. A. Kazanski; V. I. Popov

1962-01-01

173

Observation of the radiative decay D*+-> D+gamma  

E-print Network

We have observed a signal for the decay D*(+) --> D(+)gamma at a significance of 4 standard deviations. From the measured branching ratio B(D*(+) --> D(+)gamma)/B(D*(+) --> D(+)pi(0)) = 0.055 +/- 0.014 +/- 0.010 we find B(D*(+) --> D(+)gamma) = 0...

Ammar, Raymond G.; Baringer, Philip S.; Bean, Alice; Besson, David Zeke; Coppage, Don; Darling, C.; Davis, Robin E. P.; Kotov, S.; Kravchenko, I.; Kwak, Nowhan; Zhou, L.

1998-05-01

174

Gamma radiation from blazar PKS 0537-441  

NASA Technical Reports Server (NTRS)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) observed high-energy gamma rays from PKS 0537-441 during observations in 1991 July-August. Upper limits from later EGRET observations suggest time variability.

Thompson, D. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

1993-01-01

175

Gamma radiation effect on gas production in anion exchange resins  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

176

Pantothenol protects rats against some deleterious effects of gamma radiation.  

PubMed

Rats were exposed to gamma radiation from a 60Co source, receiving 0.25 Gy at weekly intervals. During 2 d before each irradiation, the animals received daily intragastric doses of 26 mg pantothenol or 15 mg beta-carotene per kg body weight. One hour after the third irradiation session, the animals were killed and their livers were analyzed. In animals not supplied with pantothenol, the irradiation resulted in a significant decrease of total liver lipids and a 50% decrease in phospholipids. Liver cholesterol was decreased by about 20%. Irradiation produced lipid peroxidation as expressed by doubling of the amounts of conjugated dienes and ketone dienes and of thiobarbituric acid reactive compounds. The amount of CoA in liver was decreased by 24% and that of reduced glutathione by 40%. The NAD+/NADH ratio was increased by 60% and the activity of NADP-dependent malate dehydrogenase (decarboxylating) was decreased by 26%. The amount of pantothenic acid and its derivatives (expressed as pantolactone-generating compounds) in blood decreased by about 80%. In rats to which pantothenol was administered, the content of pantothenic acid in blood was tripled compared to nonirradiated (control) rats, and all the biochemical parameters measured in liver were the same as in nonirradiated animals. PMID:9607598

Slyshenkov, V S; Omelyanchik, S N; Moiseenok, A G; Trebukhina, R V; Wojtczak, L

1998-04-01

177

APPLICATION OF JITTER RADIATION: GAMMA-RAY BURST PROMPT POLARIZATION  

SciTech Connect

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.

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

178

Deinococcus puniceus sp. nov., a Bacterium Isolated from Soil-Irradiated Gamma Radiation.  

PubMed

A Gram-positive, coccus-shaped, crimson-color-pigmented bacterium was isolated from soil irradiated with 5 kGy gamma radiation and was designated strain DY1(T). Cells showed growth at 10-30 °C and pH 7-11 and were oxidase-negative and catalase-positive. Phylogenetic analyses of the 16S rRNA gene showed that the strain DY1(T) belonged to the genus Deinococcus with sequence similarities to Deinococcus aquatilis CCUG 53370(T) (96.2 %) and Deinococcus navajonensis KR-114(T) (94.1 %). Strain DY1(T) showed low level of DNA relatedness with D. aquatilis CCUG 53370(T) (41.3 ± 3.9 %). The DNA G + C content of DY1(T) was 58.7 mol%. Predominant fatty acids were summed feature 3 (C16:1 ?7c/?6c), C16:0, and C17:0. The major amino acids were D-alanine, L-glutamic acid, glycine, and L-ornithine in the peptidoglycan. The major polar lipids were unknown phosphoglycolipids (PGL). Strain DY1(T) has resistance to gamma radiation and was found to be a novel species. Therefore, the strain was designated as DY1(T) (=KCTC 33027(T) = JCM 18576(T)), and the name Deinococcus puniceus sp. nov. is herein proposed. PMID:25477066

Lee, Jae-Jin; Srinivasan, Sathiyaraj; Lim, Sangyong; Joe, Minho; Im, Seonghun; Kim, Myung Kyum

2015-04-01

179

Prompt gamma radiation as a new tool to measure reactor power  

NASA Astrophysics Data System (ADS)

A new method, based on reactor prompt gamma radiation detection, for reactor power measurement is introduced and validated. To verify, the ex-core gamma radiation spectrum from the Iranian Heavy Water Zero Power Reactor (HWZPR) were measured by HPGe and NaI detectors each suitably positioned. The collective prompt gamma count rates for all or for a portion of each of 2?×2? NaI detector spectra were obtained for seven power level readings from calibrated reactor power monitors. A good linear behavior was found between gamma count rate and reactor power. The method of calibrated prompt gamma reactor power determination is a stable and reliable tool, on-line, sensitive to sudden variation of power, working in pulse mode, increasing redundancy and diversity and so improving the reactor safety. The prompt gamma counting system can be adopted and installed in other nuclear reactors to measure power.

jalali, Majid; Abdi, Mohammad Reza; davati, Mojtaba Mostajabod

2013-10-01

180

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

SciTech Connect

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.

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

181

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

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

182

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

DOEpatents

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.

Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

2014-12-30

183

A gamma-ray testing technique for spacecraft. [considering cosmic radiation effects  

NASA Technical Reports Server (NTRS)

The simulated cosmic radiation effect on a spacecraft structure is evaluated by gamma ray testing in relation to structural thickness. A drawing of the test set-up is provided and measurement errors are discussed.

Gribov, B. S.; Repin, N. N.; Sakovich, V. A.; Sakharov, V. M.

1977-01-01

184

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

E-print Network

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...

Gidden, Richmond Paul

1996-01-01

185

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

E-print Network

irradiated-fiber concentration, respect to plain concrete (without fibers and non-irradiated). Conversely an opposite effect occurs when polymer concrete is gamma irradiated, i.e. both the degree of polymerizationLuffa fibers and gamma radiation as improvement tools of polymer concrete Gonzalo Martínez

North Texas, University of

186

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

E-print Network

EXTENDING THE RESPONSE OF THE SUM COINCIDENCE SPECTROMETEP TO MULTIPLE GAMMA RADIATION CASCADES A Thesis By VICTOR DEAN HELTON Submitted to the Graduate College of the Texas AEcM University in partial fulfillment of the requirements... 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...

Helton, Victor Dean

1964-01-01

187

Influence of gamma radiation on microbiological parameters of the ethanolic fermentation of sugar-cane must  

NASA Astrophysics Data System (ADS)

The influence of gamma radiation on reducing the population of some bacteria Bacillus and Lactobacillus that usually contaminate the sugar-cane must and its effects on acidity of the medium and viability of the yeast during fermentation were evaluated. The treatment with gamma radiation reduced the bacterial load of the sugar-cane must. Consequently, the volatile acidity produced during the fermentation of the must decreased and the viability of the yeast afterwards added increased.

Alcarde, A. R.; Walder, J. M. M.; Horii, J.

2003-04-01

188

A comparison of gamma and proton radiation effects in 200 GHz SiGe HBTs  

Microsoft Academic Search

We present the results of gamma irradiation on third-generation, 200 GHz SiGe HBTs. Pre- and post-radiation dc figures-of-merit are used to quantify the tolerance of the raised extrinsic base structure to Co-60 gamma rays for varying device geometries. Additionally, the impact of technology scaling on the observed radiation response is addressed through comparisons to second generation, 120 GHz SiGe HBTs.

Akil K. Sutton; Becca M. Haugerud; A. P. Gnana Prakash; Bongim Jun; John D. Cressler; Cheryl J. Marshall; Paul W. Marshall; Ray Ladbury; Fernando Guarin; Alvin J. Joseph

2005-01-01

189

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

190

Shelf life extension of fresh turmeric ( Curcuma longa L.) using gamma radiation  

NASA Astrophysics Data System (ADS)

Gamma radiation processing was found to extend shelf life of fresh turmeric. A 5 kGy radiation dose and 10 °C storage temperature was found to keep peeled turmeric samples microbe free and acceptable until 60 days of storage. The control sample without radiation treatment spoiled within a week of storage. The changes in color, texture and moisture content of fresh turmeric due to radiation treatment were found to be statistically insignificant.

Dhanya, R.; Mishra, B. B.; Khaleel, K. M.; Cheruth, Abdul Jaleel

2009-09-01

191

RBE (relative biological effectiveness) of tritium beta radiation to gamma radiation and x-rays analyzed by both molecular and genetic methods  

SciTech Connect

The relative biological effectiveness (RBE) of tritium beta radiation to /sup 60/Co gamma radiation was determined using sex-linked recessive lethals (SLRL) induced in Drosophila melanogaster spermatozoa as the biological effect. The SLRL test, a measure of mutations induced in germ cells transmitted through successive generations, yields a linear dose-response curve in the range used in these experiments. From these ratios of the slopes of the /sup 3/H beta and the /sup 60/ Co gamma radiation linear dose response curves, an RBE of 2.7 is observed. When sources of error are considered, this observation suggests that the tritium beta particle is 2.7 /plus minus/ 0.3 times more effective per unit of energy absorbed in inducing gene mutations transmitted to successive generation than /sup 60/Co gamma radiation. Ion tracks with a high density of ions (high LET) are more efficient than tracks with a low ion density (low LET) in inducing transmissible mutations, suggesting interaction among products of ionization. Molecular analysis of x-ray induced mutations shows that most mutations are deletions ranging from a few base pairs as determined from sequence data to multi locus deletions as determined from complementation tests and Southern blots. 14 refs., 1 fig.

Lee, W.R.

1988-01-01

192

Repair of radiation damage in mammalian cells  

SciTech Connect

The responses, such as survival, mutation, and carcinogenesis, of mammalian cells and tissues to radiation are dependent not only on the magnitude of the damage to macromolecular structures - DNA, RNA, protein, and membranes - but on the rates of macromolecular syntheses of cells relative to the half-lives of the damages. Cells possess a number of mechanisms for repairing damage to DNA. If the repair systems are rapid and error free, cells can tolerate much larger doses than if repair is slow or error prone. It is important to understand the effects of radiation and the repair of radiation damage because there exist reasonable amounts of epidemiological data that permits the construction of dose-response curves for humans. The shapes of such curves or the magnitude of the response will depend on repair. Radiation damage is emphasized because: (a) radiation dosimetry, with all its uncertainties for populations, is excellent compared to chemical dosimetry; (b) a number of cancer-prone diseases are known in which there are defects in DNA repair and radiation results in more chromosomal damage in cells from such individuals than in cells from normal individuals; (c) in some cases, specific radiation products in DNA have been correlated with biological effects, and (d) many chemical effects seem to mimic radiation effects. A further reason for emphasizing damage to DNA is the wealth of experimental evidence indicating that damages to DNA can be initiating events in carcinogenesis.

Setlow, R.B.

1981-01-01

193

Displacement damage induced in iron by gammas and neutrons under irradiation in the IFMIF test cell  

NASA Astrophysics Data System (ADS)

This work presents a complete comparative analysis of the radiation damage induced in iron-based materials in IFMIF by photons and neutrons. The gamma induced damage takes into account, for the first time, both photonuclear and photoatomic reaction mechanisms. The relevant cross sections were taken from available data evaluations. The gamma and neutron radiation fields were calculated by the McDeLicious Monte Carlo code using a 3-D geometry model. Finally the gamma and neutron induced damages in the iron have been assessed inside the IFMIF test cell and the surrounding concrete walls. It was found that the photoatomic mechanism dominates the photonuclear with at least one hundred times higher damage rates. The ratio of the gamma and the neutron induced displacement damage was found to be 10 -3 inside the concrete wall and 10 -5 in the components close to d-Li source. This fraction may increase a few times due to the uncertainty of the evaluated ?-dpa cross sections and the different surviving probabilities for defects produced by gammas and neutrons, nevertheless unlikely exceed 1%.

Simakov, S. P.; Fischer, U.

2011-10-01

194

Asymmetrical SRAM Cells For Radiation Tests  

NASA Technical Reports Server (NTRS)

Features of circuits altered to increase or decrease sensitivity to radiation. State-space analysis used to analyze single-event-upset behavior of memory cell. When voltage on node a is set at one of indicated initial values Vao and then released, voltages on nodes a and b then follow indicated trajectory to final logic "one" or logic "zero" state. Ability to do this important for design of radiation-detecting integrated circuits (deliberately made more sensitive to ionizing radiation) and "radiation-hardened" integrated circuits - those intended to be relatively invulnerable to intense radiation.

Buehler, Martin G.

1989-01-01

195

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

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

196

Evaluation of the Combined Effects of Gamma Radiation and High Dietary Iron on Peripheral Leukocyte Distribution and Function  

NASA Technical Reports Server (NTRS)

NASA is concerned with the health risks to astronauts, particularly those risks related to radiation exposure. Both radiation and increased iron stores can independently increase oxidative damage, resulting in protein, lipid and DNA oxidation. Oxidative stress increases the risk of many health problems including cancer, cataracts, and heart disease. This study, a subset of a larger interdisciplinary investigation of the combined effect of iron overload on sensitivity to radiation injury, monitored immune parameters in the peripheral blood of rats subjected to gamma radiation, high dietary iron or both. Specific immune measures consisted of (A) peripheral leukocyte distribution; (B) plasma cytokine levels; (C) cytokine production profiles following whole blood stimulation of either T cells or monocytes.

Crucian, Brian E.; Morgan, Jennifer L. L.; Quiriarte, Heather A.; Sams, Clarence F.; Smith, Scott M.; Zwart, Sara R.

2011-01-01

197

CDDO-Me Protects Normal Lung and Breast Epithelial Cells but Not Cancer Cells from Radiation  

PubMed Central

Although radiation therapy is commonly used for treatment for many human diseases including cancer, ionizing radiation produces reactive oxygen species that can damage both cancer and healthy cells. Synthetic triterpenoids, including CDDO-Me, act as anti-inflammatory and antioxidant modulators primarily by inducing the transcription factor Nrf2 to activate downstream genes containing antioxidant response elements (AREs). In the present series of experiments, we determined if CDDO-Me can be used as a radioprotector in normal non-cancerous human lung and breast epithelial cells, in comparison to lung and breast cancer cell lines. A panel of normal non-cancerous, partially cancer progressed, and cancer cell lines from both lung and breast tissue was exposed to gamma radiation with and without pre-treatment with CDDO-Me. CDDO-Me was an effective radioprotector when given ?18 hours before radiation in epithelial cells (average dose modifying factor (DMF)?=?1.3), and Nrf2 function was necessary for CDDO-Me to exert these radioprotective effects. CDDO-Me did not protect cancer lines tested from radiation-induced cytotoxicity, nor did it protect experimentally transformed human bronchial epithelial cells (HBECs) with progressive oncogenic manipulations. CDDO-Me also protected human lymphocytes against radiation-induced DNA damage. A therapeutic window exists in which CDDO-Me protects normal cells from radiation by activating the Nrf2 pathway, but does not protect experimentally transformed or cancer cell lines. This suggests that use of this oral available, non-toxic class of drug can protect non-cancerous healthy cells during radiotherapy, resulting in better outcomes and less toxicity for patients. PMID:25536195

El-Ashmawy, Mariam; Delgado, Oliver; Cardentey, Agnelio; Wright, Woodring E.; Shay, Jerry W.

2014-01-01

198

Surface heterogeneity of tumor cells and changes upon ionizing radiation  

SciTech Connect

Heterogeneous distribution of surface domains is a characteristic feature of the tumor cell surface and the distribution differs from that of normal cells. During the malignant transformation the heterogeneity may change or disappear. Cell lines with various metastasizing capacities show different distributions of membrane domains or other differences in membrane or surface organization. We have demonstrated that the amount and distribution of negatively charged sites of B 16 melanoma membranes changed upon ionizing radiation (X-ray, {sup 60}Co-gamma). In the case of the P 388 lymphoma, however, only the amount of negatively charged sites change after irradiation, the distribution remains unaltered. Both features proved to be radioresistant in human lymphoid leukemic cells. 93 references.

Somosy, Z.; Csuka, O.; Kubasova, T.; Kovacs, J.; Koeteles, G.J. (Frederic Joliot-Curie National Research Institute for Radiobiology and Radiohygiene, Budapest (Hungary))

1989-09-01

199

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

PubMed

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

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

2014-09-01

200

Comptonization of diffuse ambient radiation by a relativistic jet: The source of gamma rays from blazars?  

NASA Technical Reports Server (NTRS)

Recent Energy Gamma Ray Experiment Telescope (EGRET) observations of blazars have revealed strong, variable gamma-ray fluxes with no signatures of gamma-ray absorption by pair production. This radiation probably originates from the inner parts of relativistic jets which are aimed nearly toward us. On sub-parsec scales, the jet will be pervaded by radiation from the broad-line region, as well as by photons from the central continuum source (some of which will be scattered by thermal plasma). In a frame moving with the relativistic outflow, the energy of this ambient radiation would be enhanced. This radiation would be Comptonized by both cold and relativistic electrons in the jet, yielding (in the observer's frame) a collimated beam of X-rays and gamma rays. On the assumption that this process dominates self-Comptonization of synchrotron radiation, we develop a self-consistent model for variable gamma-ray emission, involving a single population of relativistic electrons accelerated by a disturbance in the jet. The spectral break between the X-ray and gamma-ray band, observed in 3C 279 and deduced for other blazars, results from inefficient radiative cooling of lower energy electrons. The existence of such a break strongly favors a model involving Comptonization of an external radiation field over a synchrotron self-Compton model. We derive constraints on such model parameters as the location and speed of the source, its dimensions and internal physical parameters, the maximum photon energies produced in the source, and the density and distribution of ambient radiation. Finally, we discuss how observations might discriminate between our model and alternative ones invoking Comptonization of ambient radiation.

Sikora, Marek; Begelman, Mitchell C.; Rees, Martin J.

1994-01-01

201

AMINO ACIDS IN COMETS AND METEORITES: STABILITY UNDER GAMMA RADIATION AND PRESERVATION OF THE  

E-print Network

AMINO ACIDS IN COMETS AND METEORITES: STABILITY UNDER GAMMA RADIATION AND PRESERVATION, Via Salaria Km 29,300, 00016 Monterotondo Stazione, Rome, Italy. 5 CSIC, Spain. Abstract Amino acids. We present laboratory studies testing the stability of amino acids against radiation photolysis. All

202

Gamma Ray Bursts from Interaction of Relativistic Flows with Radiation Fields  

E-print Network

Relativistic flows resulting from sudden explosive events upscatter ambient interstellar photons of local radiation fields. For Lorentz factor $ > 100$ and dense optical - UV radiation fields the emergent signal is a typical gamma ray burst. Presumably the explosions occur in dense globular clusters or in galactic nuclei, at cosmological distances.

Amotz Shemi

1994-04-20

203

The myth of cell phone radiation  

E-print Network

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.

Natarajan, Vasant

2012-01-01

204

The myth of cell phone radiation  

E-print Network

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.

Vasant Natarajan

2013-11-04

205

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

NASA Astrophysics Data System (ADS)

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.

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

2005-08-01

206

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

SciTech Connect

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.

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

2012-09-06

207

Distribution of terrestrial gamma radiation dose rate in the eastern coastal area of Odisha, India.  

PubMed

Terrestrial gamma radiation is one of the important radiation exposures on the earth's surface that results from the three primordial radionuclides (226)Ra, (232)Th and (40)K. The elemental concentration of these elements in the earth's crust could result in the anomalous variation of the terrestrial gamma radiation in the environment. The geology of the local area plays an important role in distribution of these radioactive elements. Environmental terrestrial gamma radiation dose rates were measured around the eastern coastal area of Odisha with the objective of establishing baseline data on the background radiation level. The values of the terrestrial gamma radiation dose rate vary significantly at different locations in the study area. The values of the terrestrial gamma dose rate ranged from 77 to 1651 nGy h(-1), with an average of 230 nGy h(-1). During the measurement of the terrestrial gamma dose rate, sand and soil samples were also collected for the assessment of natural radionuclides. The activities of (226)Ra, (232)Th and (40)K from these samples were measured using a gamma-ray spectrometry with a NaI(Tl) detector. Activity concentrations of (226)Ra, (232)Th and (40)K ranged from 15.6 to 69 Bq kg(-1) with an average of 46.7 Bq kg(-1), from 28.9 to 973 Bq kg(-1) with an average of 250 Bq kg(-1) and from 139 to 952 Bq kg(-1) with an average of 429, respectively. The detailed significance of these studies has been discussed from the radiation protection point of view. PMID:22874894

Gusain, G S; Rautela, B S; Sahoo, S K; Ishikawa, T; Prasad, G; Omori, Y; Sorimachi, A; Tokonami, S; Ramola, R C

2012-11-01

208

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

SciTech Connect

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.

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

209

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

SciTech Connect

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.

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

1981-07-01

210

[Transfection with the E1A and E1B-19kDa oncogenes does not prevent rat embryo fibroblasts from cell cycle arrest after gamma-radiation].  

PubMed

Introduction of the E1A early region of the human adenovirus type 5 impairs the ability of mammalian cells to arrest the cell cycle at G1/S after damage. Two-parameter fluorescent-activated cell sorting (FACS) with iododeoxyuridine revealed the radiation-induced G1/S arrest in rat embryo fibroblasts transformed with the complementing E1A + E1B-19 kDa oncogenes. This was due to selective inhibition of CycIE/Cdk2-associated kinase activity, while activities of type 2 kinase and of CyclA/Cdk2 complexes remained unchanged. The inhibitor of G1-phase cyclin kinases, p21/Waf1, was accumulated and interacted with target kinases both in normal and in transformed cells after irradiation. As shown by immunoprecipitation, p21/Waf1 formed complexes with the E1A on coproducts in the transformants, which possibly accounted for its functional inactivation. Kinase modification in cyclin-kinase complexes was assumed to play a key role in regulation of cyclin-dependent kinases in the transformants with inactivated p21/Waf1. PMID:11862714

Bulavin, D V; Tararova, N D; Brichkina, A I; Aksenova, N D; Pospelov, V A; Pospelova, T V

2002-01-01

211

Preparation of fowl testes as recipient organs to germ-line chimeras by means of gamma-radiation.  

PubMed

1. The aim of the study was to investigate the possibility of preparing adult fowl testes for the production of exogenous germ-lines by eradication of recipient spermatogenesis using gamma-radiation. 2. A comparison between several radiation therapy treatments (based on 60Co isotope) of male testes was conducted using gamma-rays of 18, 22 and 26 Gy in a single dose or repeated doses of 5 x 8 Gy over a 15-d period. Sperm concentration and motility were determined after each treatment. 3. Altered spermatogenesis was observed after a single treatment dose of 18 Gy, while single doses of 26 Gy were followed by reduced sperm numbers (from 22 x 10(9) to 31 x 10(6) sperm/ml) within 60 to 100 d after treatment. After a single treatment of 26 Gy sperm motility was reduced by 50%. In contrast, a fractionated treatment (5 x 8 Gy) with gamma-rays halted spermatogenesis 39 d after the distribution of the first 8 Gy dose. 4. Observations of the seminiferous tubules by electron microscopy performed 12 months after this treatment confirmed that moderate doses of gamma-rays (8 Gy) distributed repeatedly (5 x) over a limited period (15 d) sterilise adult fowl testes but maintain morphologically normal somatic (Leydig and Sertoli) cell populations. PMID:14584856

Trefil, P; Polak, J; Poplstein, M; Mikus, T; Kotrbová, A; Rozinek, J

2003-09-01

212

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

PubMed

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

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

2014-08-01

213

Changes in the biological properties of an ordinary chernozem exposed to gamma radiation  

NASA Astrophysics Data System (ADS)

The dynamics of changes in the number of microorganisms and biochemical properties of an ordinary chernozem were studied in model experiments 3, 30, and 90 days after the soil was subjected to gamma radiation at doses of 0.12-2.0 Mrad. The microscopic fungi are the most radiosensitive soil microorganisms. In 90 days of incubation after the gamma radiation, the number of microorganisms remained lower than that in the control variant by 31-96% in accordance with the dose. The enzyme activity of the ordinary chernozem, as compared to that of the microorganisms, was more resistant to the gamma radiation. The integral index of the soil biological state (ISBSI) decreased by 20-63% upon the radiation depending on the dose applied. After 90 days, the ISBSI value was close to the control variant (doses of 0.1-0.5 Mrad), whereas, in the variants with high doses of radiation (1.0 and 2.0 Mrad), its values were 46 and 59% lower, respectively, than in the control. The rate of restoring of the biological properties was related to the dose of radiation: the less the dose, the quicker the rate of restoration of the biological properties of the ordinary chernozem. However, at the high levels of gamma radiation, some biological properties were not restored even after 90 days.

Denisova, T. V.; Kazeev, K. Sh.; Kolesnikov, S. I.; Val'Kov, V. F.

2007-09-01

214

Alterations of human acellular tissue matrix by gamma irradiation: histology, biomechanical property, stability, in vitro cell repopulation, and remodeling.  

PubMed

AlloDerm, a processed acellular human tissue matrix, is used in a number of surgical applications for tissue repair and regeneration. In the present work, AlloDerm serves as a model system for studying gamma radiation-induced changes in tissue structure and stability as well as the effect of such changes on the cell-matrix interactions, including cell repopulation and matrix remodeling. AlloDerm tissue matrix was treated with 2-30 kGy gamma irradiation at room temperature. Gamma irradiation reduced the swelling of tissue matrix upon rehydration and caused significant structural modifications, including collagen condensation and hole formation in collagen fibres. The tensile strength of AlloDerm increased at low gamma dose but decreased with increasing gamma dosage. The elasticity of irradiated AlloDerm was reduced significantly. Calorimetric study showed that gamma irradiation destabilized the tissue matrix, resulting in greater susceptibility to proteolytic enzyme degradation. Although gamma irradiation did not affect in vitro proliferation of fibroblast cells, it promoted tissue degradation upon cell repopulation and influenced synthesis and deposition of new collagen. PMID:17497685

Gouk, Sok-Siam; Lim, Tit-Meng; Teoh, Swee-Hin; Sun, Wendell Q

2008-01-01

215

Radiative Opacities and Photosphere Models for Soft GammaRay  

E-print Network

of the electron Thomson scattering cross section for ra­ diation polarized perpendicular to the magnetic field consider the radiative processes for conditions expected in photo­ spheres of neutron stars (NSs with allowance for these effects. RADIATIVE OPACITIES We consider the radiative processes in a completely ionized

216

Endothelial cell damage after gamma-irradiation in vitro: impaired uptake of alpha-aminoisobutyric acid. [137Cs  

SciTech Connect

The effects of gamma-irradiation with a cesium-137 source were assessed on endothelial cells isolated from bovine pulmonary arteries and maintained in culture. The radiobiologic parameters that characterize the dose-response survival curve for these cells, expressed as mean +/- SD were found to be n . 1.6 +/- 0.2, Dq . 71 +/- 13 rads, and Do . 161 +/- 35 rads, indicating a relatively low capacity of these cells to accumulate or repair radiation damage. Increasing doses of radiation led to decreasing uptake by endothelial cells of (14C)2-aminoisobutyric acid (AIB), a Na+-dependent and nonmetabolizable amino acid. A dose of 500 rads, which caused marked inhibition of cell survival, resulted in a 45% decrease in AIB uptake at 6 h and a 69% decrease in uptake at 24 h after irradiation. No morphologic abnormality was noted in these cells by light microscopy at 24 h after this dose of radiation. Bovine pulmonary artery fibroblasts, on the other hand, showed no significant impairment in uptake of AIB 24 h after exposure to doses of radiation as high as 5,000 rads. The uptake by endothelial cells of (14C)1-aminocyclopentane-1-carboxylic acid, an amino acid transported by a Na+-independent process, was not influenced by 5,000 rads of radiation. Our studies show that endothelial cells are sensitive to radiation and that impaired Na+-dependent uptake of AIB represents an early event in radiation damage to the endothelial cell.

Kwock, L.; Douglas, W.H.; Lin, P.S.; Baur, W.E.; Fanburg, B.L.

1982-01-01

217

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)

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.

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

2001-01-01

218

Astrophysical applications of Delbrück scattering: Dust scattered gamma radiation from gamma ray bursts  

NASA Astrophysics Data System (ADS)

A preliminary, and perhaps the first, study of astrophysical applications of Delbrück scattering in a gamma-ray emitting celestial object like a gamma-ray burst (GRB) has been made. At energies?100 MeV the elastic scattering of gamma-ray photons off the molecular dust surrounding the GRB site is dominated by Delbrück scattering. Expressions for Delbrück-scattered gamma-ray flux as a function of time has been obtained for a few selected energies by assuming a simple model of GRB. These are compared with Compton-scattered flux. At certain situations, interestingly, the former is found to exceed the latter for the first few milliseconds of the burst. The issue of detectability of Delbrück-scattered gamma-ray echo from the cloud of a GRB is discussed. Although it is observed that the detection of such an echo is not within the capability of the presently operating gamma-ray missions such as Fermi LAT, a rough estimate shows that one can be optimistic that future generation gamma-ray telescopes might be able to see such photons' contribution to the total flux.

Kunwar, B.; Bhadra, A.; Gupta, S. K. Sen

2014-02-01

219

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

E-print Network

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.

H. T. Liu; J. M. Bai

2008-07-20

220

Gamma-radiation sensitivity and polymorphisms in RAD51L1 modulate glioma risk  

PubMed Central

Background: DNA strand breaks pose the greatest threat to genomic stability. Genetically determined mutagen sensitivity predisposes individuals to a variety of cancers, including glioma. However, polymorphisms in DNA strand break repair genes that may determine mutagen sensitivity are not well studied in cancer risk, especially in gliomas. Methods: We correlated genotype data for tag single-nucleotide polymorphisms (tSNPs) of DNA strand break repair genes with a gamma-radiation-induced mutagen sensitivity phenotype [expressed as mean breaks per cell (B/C)] in samples from 426 glioma patients. We also conducted analysis to assess joint and haplotype effects of single-nucleotide polymorphisms (SNPs) on mutagen sensitivity. We further validate our results in an independent external control group totaling 662 subjects. Results: Of the 392 tSNPs examined, we found that mutagen sensitivity was modified by one tSNP in the EME2 gene and six tSNPs in the RAD51L1 gene (P < 0.01). Among the six RAD51L1 SNPs tested in the validation set, one (RAD51L1 rs2180611) was significantly associated with mutagen sensitivity (P = 0.025). Moreover, we found a significant dose–response relationship between the mutagen sensitivity and the number of adverse tSNP genotypes. Furthermore, haplotype analysis revealed that RAD51L1 haplotypes F-A (zero adverse allele) and F-E (six adverse alleles) exhibited the lowest (0.42) and highest (0.93) mean B/C values, respectively. A similar dose–response relationship also existed between the mutagen sensitivity and the number of adverse haplotypes. Conclusion: These results suggest that polymorphisms in and haplotypes of the RAD51L1 gene, which is involved in the double-strand break repair pathway, modulate gamma-radiation-induced mutagen sensitivity. PMID:20610542

Liu, Yanhong; Shete, Sanjay; Wang, Li-E; El-Zein, Randa; Etzel, Carol J.; Liang, Fu-Wen; Armstrong, Georgina; Tsavachidis, Spyros; Gilbert, Mark R.; Aldape, Kenneth D.; Xing, Jinliang; Wu, Xifeng; Wei, Qingyi; Bondy, Melissa L.

2010-01-01

221

THE ESTIMATION OF GAMMA-RAY SHIELDING FOR HOT CELLS  

Microsoft Academic Search

Considerations involved in estimating the thickness of gamma shielding ; for hot cells are outlined. Some simplified attenuation factor curves for making ; shielding estimates quickly and usually with sufficient accuracy for final design ; purposes are described. Significant sources of error are discussed. (M.C.G.);

1963-01-01

222

Terrestrial Gamma-Ray Flashes, Relativistic Runaway, and High-Energy Radiation in the Atmosphere  

NASA Astrophysics Data System (ADS)

High energy radiation from tens of keV to tens of MeV in energy, the transition region from x-rays to gamma rays, has been observed in association with high electric fields in air in many contexts: from the ground, associated with thunderstorms and with individual flashes of natural and rocket-triggered lightning [1, 2, 3, 4, 5, 6, 7, 8] from sparks in the laboratory [9, 10, 11, 12], from Earth orbit in the form of millisecond Terrestrial Gamma-ray Flashes (TGFs) [13, 14], and at intermediate altitudes from aircraft and balloons [15, 16, 17, 18, 19]. The gamma radiation in all cases is almost certainly bremsstrahlung generated by the collision of accelerated electrons with nuclei in the atmosphere. The penetrating gamma-rays can provide a mechanism for coupling between the troposphere, mesosphere, ionosphere and magnetosphere in the form of energetic particles and ionization.

Smith, David M.

2009-04-01

223

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

SciTech Connect

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.

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

1989-06-01

224

Radiation tolerance of vertical junction solar cells  

NASA Technical Reports Server (NTRS)

Extensive radiation testing of vertical junction (VJ) solar cells demonstrated a radiation tolerance better than both planar silicon cells and at least one type of (AlGa)As-GaAs cell. Due to tradeoffs between short circuit current and open circuit voltage, the end of life (10 to the 16th power 1 MeV electrons/sq cm) maximum power point is nearly independent of bulk resistivity between 2 and 10 ohm cm, increases slightly with increasing wafer thickness between 3 and 11 mils, and increases slightly with increasing groove depth between 1 and 3 mils.

Schelnine, A.; Wohlgemuth, J.

1980-01-01

225

Breast cancer stem cells and radiation  

NASA Astrophysics Data System (ADS)

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.

Phillips, Tiffany Marie

2007-12-01

226

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

PubMed

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

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

227

Radiation damage effects on X- and gamma-ray N+NPP+ silicon detectors  

Microsoft Academic Search

The paper describes some results concerning technology and behaviour of Xand gamma-ray N+PP+ silicon detectors used in physics research, industrial and medical radiography, and non-destructive testing. Devices manufactured under this technology proved to be stable after an exposure in high intensity gamma field with the dose range of 10 krad-5 Mrad. Nuclear radiation resistance was studied by irradiation with 60Co

V. Cimpoca; M. Petris; R. Ruscu; R. Moraru; M. Breten; M. Cimpoca

1997-01-01

228

Small scale local gamma ray features. [galactic radiation spectra  

NASA Technical Reports Server (NTRS)

In order to draw implications from nearby gamma-ray emission, the different ways that can be used to obtain an estimate of the amount of matter on each line of sight are investigated. It is shown that, within present uncertainties, the cosmic ray intensity inside molecular clouds within 1 kpc from the sun is the same as the cosmic ray intensity measured at the sun. In the last part, what can be learned from a comparison of far infrared and gamma-ray data is discussed.

Puget, J. L.; Ryter, C.; Serra, G.

1977-01-01

229

Dipole analysis on EGRET data of extragalactic gamma ray background radiation  

NASA Technical Reports Server (NTRS)

A dipole analysis on the EGRET (Energetic Gamma-Ray Experimental Telescope) data seems to be one of the numerous subjects that can be investigated for the extragalactic gamma ray background radiation. By the end of the first one and half years after launch, the all-sky survey program of GRO (Gamma Ray Observatory) will be completed. The EGRET detector will cover the full sky area fairly well by that time. A set of gamma ray data suitable for dipole moment calculations will be available. Furthermore, there now exist in the literature several dipole anisotropy results calculated for optical and infrared observations on the distribution of galaxies in the full sky. The results of dipole moment analysis from gamma ray observation can be compared with those at other wavebands, and hopefully some deeper understanding can be gained on the large scale structure of the Universe.

Lin, Ying-Chi

1990-01-01

230

LDEF solar cell radiation effects analysis  

NASA Technical Reports Server (NTRS)

Because of the extended time that the Long Duration Exposure Facility (LDEF) mission stayed in space, the solar cells on the satellite experienced greater environments than originally planned. The cells showed an overall degradation in performance that is due to the combined effects of the various space environments. The purpose of this analysis is to calculate the effect of the accumulated radiation on the solar cells, thereby helping Marshall Space Flight Center (MSFC) to unravel the relative power degradation from the different environments.

Rives, Carol J.; Azarewicz, Joseph L.; Massengill, Lloyd

1993-01-01

231

Slow elimination of phosphorylated histone {gamma}-H2AX from DNA of terminally differentiated mouse heart cells in situ  

SciTech Connect

Phosphorylation of replacement histone H2AX occurs in megabase chromatin domains around double-strand DNA breaks (DSBs) and this modification (called {gamma}-H2AX) may serve as a useful marker of genome damage and repair in terminally differentiated cells. Here using immunohistochemistry we studied kinetics of {gamma}-H2AX formation and elimination in the X-irradiated mouse heart and renal epithelial tissues in situ. Unirradiated tissues have 3-5% {gamma}-H2AX-positive cells and in tissues fixed 1 h after X-irradiation {gamma}-H2AX-positive nuclei are induced in a dose-dependent manner approaching 20-30% after 3 Gy of IR. Analysis of mouse tissues at different times after 3 Gy of IR showed that maximal induction of {gamma}-H2AX in heart is observed 20 min after IR and then is decreased slowly with about half remaining 23 h later. In renal epithelium maximum of the {gamma}-H2AX-positive cells is observed 40 min after IR and then decreases to control values in 23 h. This indicates that there are significant variations between non-proliferating mammalian tissues in the initial H2AX phosphorylation rate as well as in the rate of {gamma}-H2AX elimination after X-irradiation, which should be taken into account in the analysis of radiation responses.

Gavrilov, Boris [Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg (Russian Federation); Vezhenkova, Irina [Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg (Russian Federation); Firsanov, Denis [Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg (Russian Federation); Solovjeva, Liudmila [Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg (Russian Federation); Svetlova, Maria [Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg (Russian Federation); Mikhailov, Vyacheslav [Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg (Russian Federation); Tomilin, Nikolai [Institute of Cytology, Russian Academy of Sciences, 194064 St. Petersburg (Russian Federation)]. E-mail: nvtom@hotmail.com

2006-09-08

232

Clinical Applications of Gamma Delta T Cells with Multivalent Immunity  

PubMed Central

?? 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

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

2014-01-01

233

Peroxisome proliferator-activated receptor gamma overexpression suppresses proliferation of human colon cancer cells  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer We examined the correlation between PPAR{gamma} expression and cell proliferation. Black-Right-Pointing-Pointer PPAR{gamma} overexpression reduces cell viability. Black-Right-Pointing-Pointer We show the synergistic effect of cell growth inhibition by a PPAR{gamma} agonist. -- Abstract: Peroxisome proliferator-activated receptor gamma (PPAR{gamma}) plays an important role in the differentiation of intestinal cells and tissues. Our previous reports indicate that PPAR{gamma} is expressed at considerable levels in human colon cancer cells. This suggests that PPAR{gamma} expression may be an important factor for cell growth regulation in colon cancer. In this study, we investigated PPAR{gamma} expression in 4 human colon cancer cell lines, HT-29, LOVO, DLD-1, and Caco-2. Real-time polymerase chain reaction (PCR) and Western blot analysis revealed that the relative levels of PPAR{gamma} mRNA and protein in these cells were in the order HT-29 > LOVO > Caco-2 > DLD-1. We also found that PPAR{gamma} overexpression promoted cell growth inhibition in PPAR{gamma} lower-expressing cell lines (Caco-2 and DLD-1), but not in higher-expressing cells (HT-29 and LOVO). We observed a correlation between the level of PPAR{gamma} expression and the cells' sensitivity for proliferation.

Tsukahara, Tamotsu, E-mail: ttamotsu@shinshu-u.ac.jp [Department of Integrative Physiology and Bio-System Control, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan)] [Department of Integrative Physiology and Bio-System Control, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Haniu, Hisao [Department of Orthopaedic Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan)] [Department of Orthopaedic Surgery, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan)

2012-08-03

234

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

DOEpatents

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.

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

2013-02-12

235

A Grey Radiative Transfer Procedure For Gamma-ray Transfer in Supernovae  

E-print Network

The gamma-ray transfer in supernovae for the purposes of energy deposition in the ejecta can be approximated fairly accurately as frequency-integrated (grey) radiative transfer using a mean opacity as shown by Swartz, Sutherland, & Harkness (SSH). In SSH's grey radiative transfer procedure (unoptimized) the mean opacity is a pure absorption opacity and it is a constant aside from a usually weak composition dependence. In this paper, we present a variation on the SSH procedure which uses multiple mean opacities which have both absorption and scattering components. There is a mean opacity for each order of Compton scattering. A local-state (LS) approximation permits an analytic solution for the gamma-ray transfer of scattered gamma-ray fields. The LS approximation is admittedly crude, but the scattered fields are always of lesser importance to the energy deposition. We call our procedure the LS grey radiative transfer procedure or LS procedure for short. For a standard Type Ia supernova (SN Ia) model the uncertainty in gamma-ray energy deposition is estimated to be of order 10 % or less. The LS procedure code used for this paper can be obtained by request from the author. For completeness and easy reference, we include in this paper a review of the gamma-ray opacities important in supernovae, a discussion of the appropriate mean opacity prescription, and a discussion of the errors arising from neglecting time-dependent and non-static radiative transfer effects.

David J. Jeffery

1998-11-23

236

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

SciTech Connect

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.

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

237

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

SciTech Connect

This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

Not Available

1992-01-01

238

Neutron and gamma radiation effects in proton exchanged optical waveguides.  

PubMed

The effect of neutron and gamma ray irradiations on the optical properties of proton exchanged Z-cut lithium niobate optical planar waveguides were investigated. The damage thresholds were found by optical characterization for waveguides exchanged either in pure or diluted proton source. PMID:19451950

Passaro, Vittorio; Armenise, Mario

2002-09-01

239

Gamma Radiation Induced Calibration Shift for Four Cryogenic Thermometer Types  

Microsoft Academic Search

Cryogenic temperature sensors utilized in space environments are exposed to ionizing radiation with the total dose dependent upon the length of the mission. Based upon their minimal size and robust packaging, four models of cryogenic Resistance Thermometer Devices (RTDs) manufactured by Lake Shore Cryotronics, Inc. were tested to determine their reliability for space applications with regard to radiation. Samples of

S. Scott Courts; C. J. Yeager

2004-01-01

240

Effective gamma-ray doses due to natural radiation from soils of southeastern Brazil  

SciTech Connect

We have used gamma-ray spectrometry to study the distribution of natural radiation from soils of southeastern Brazil: Billings reservoir, Sao Bernardo do Campo Parks, Diadema Parks, Interlagos region, Sao Paulo, and soil from Sao Paulo and Rio de Janeiro beaches. In most of the regions studied we have found that the dose due the external exposure to gamma-rays, proceeding from natural terrestrial elements, are between the values 0.3 and 0.6 mSv/year, established by the United Nations Scientific Committee on the Effects of Atomic Radiation.

Silveira, M. A. G.; Moreira, R. H.; Bellini, B. S. [Centro Universitario da FEI, Sao Bernardo do Campo, Sao Paulo (Brazil); Medina, N. H.; Aguiar, V. A. P. [Instituto de Fisica da Universidade de Sao Paulo, Sao Paulo (Brazil)

2010-08-04

241

Effective gamma-ray doses due to natural radiation from soils of southeastern Brazil  

NASA Astrophysics Data System (ADS)

We have used gamma-ray spectrometry to study the distribution of natural radiation from soils of southeastern Brazil: Billings reservoir, Sa~o Bernardo do Campo Parks, Diadema Parks, Interlagos region, Sa~o Paulo, and soil from Sa~o Paulo and Rio de Janeiro beaches. In most of the regions studied we have found that the dose due the external exposure to gamma-rays, proceeding from natural terrestrial elements, are between the values 0.3 and 0.6 mSv/year, established by the United Nations Scientific Committee on the Effects of Atomic Radiation.

Silveira, M. A. G.; Medina, N. H.; Moreira, R. H.; Bellini, B. S.; Aguiar, V. A. P.

2010-08-01

242

Calculated thickness of tungsten alloy required for specified attenuation of gamma radiation from Cs-137  

NASA Astrophysics Data System (ADS)

The traditional method of evaluating and calibrating health physics instruments is to use a calibrator that consists of a single high-activity gamma radiation source with different attenuators to select the radiation level desired for testing. To have accurate radiation intensities inside the calibrator cavity, the attenuators must be designed from precise absorption calculations. This paper reports calculations made to determine the thickness of tungsten alloy metal required for specific attenuation. These calculations include the buildup contribution by secondary scattering radiation, and they are compared to values calculated with the buildup factor omitted.

Chiles, M. M.; Allin, G. W.; Pace, J. V., III

1991-11-01

243

Selective gamma-chain T-cell receptor gene rearrangements in a patient with Omenn's syndrome: absence of V-II subgroup (V gamma 9) transcripts.  

PubMed Central

Only gamma-chain T-cell receptor transcripts utilizing V-1 subgroup gene segments were found in peripheral blood lymphocytes from a patient with Omenn's syndrome. gamma-Chain T-cell receptor transcripts utilizing the V gamma 9 (V-II subgroup) gene segment were absent in peripheral blood lymphocytes from this patient. V gamma 9 J gamma 1.2 C gamma 1 rearrangements are those primarily found in peripheral blood lymphocytes (70 to 85%) from normal donors. PMID:8877149

Mathioudakis, G; Good, R A; Chernajovsky, Y; Day, N K; Platsoucas, C D

1996-01-01

244

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

Microsoft Academic Search

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

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

2003-01-01

245

Atypical radiation response of SCID cells  

NASA Astrophysics Data System (ADS)

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.

Chawapun, Nisa

246

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

PubMed

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

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

2015-01-01

247

Microwave and gamma radiation observations of soil moisture  

NASA Technical Reports Server (NTRS)

The unique dielectric properties of water at microwave wavelengths afford the possibility for remotely sensing the moisture content in the surface layer of the soil. The surface emissivity and reflectivity for the soils at these wavelengths are strong functions of its moisture content. The changes in emissivity can be observed by passive microwave techniques (radiometry) and the change in reflectivity can be observed by active microwave techniques (radar). The difference in the natural terrestrial gamma ray flux measured for wet and dry soil may be used to determine soil moisture. The presence of water moisture in the soil causes an effective increase in soil density, resulting in an increased attenuation of the gamma flux for wet soil and a corresponding lower flux above the ground surface.

Schmugge, T. J.; Njoku, E. G.; Peck, E.; Ulaby, F. T.

1979-01-01

248

Radiation detection system for portable gamma-ray spectroscopy  

DOEpatents

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.

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

249

Comparison of gamma radiation performance of a range of CMOS a\\/D converters under biased conditions  

Microsoft Academic Search

Radiation effects on analog and mixed signal semiconductor devices are a major concern in space and nuclear applications. Significant degradation has been observed in A\\/D converters in a radiation environment. In fact, recent advances in A\\/D converters have further reduced the radiation tolerance of these converters on account of their complex circuitry. This paper studies the effects of gamma radiation

Vivek Agarwal; Sagar D. Birkar

2005-01-01

250

High-energy gamma radiation from extragalactic radio sources  

NASA Technical Reports Server (NTRS)

We propose that the important relationship between 3C 273 and 3C 279, the first two extragalactic sources detected at over 100 MeV energies, is their superluminal nature. In support of this conjecture, we propose a kinematic focusing mechanism, based on Compton scattering of accretion-disk photons by relativistic nonthermal electrons in the jet, that preferentially emits gamma rays in the superluminal direction.

Dermer, C. D.; Schlickeiser, R.; Mastichiadis, A.

1992-01-01

251

SCINTILLATION METHOD FOR DOSIMETRY OF ROENTGEN AND GAMMA RADIATION  

Microsoft Academic Search

The high radiation sensitivity of an air-equivalent scintillator is ; discussed. The possibility of creating a scintillation dosimeter with a high ; radiation sensitivity not worse than plus or minus 6.0% in the energy range 30-; 130 kev with efficiency not less than 0.1 mr\\/hr is considered. The possibility ; of increasing the efficiency is also discussed. (tr-auth);

M. I. Arsaev; N. E. Sulimova

1963-01-01

252

Jitter radiation in gamma-ray bursts and their afterglows: emission and self-absorption  

Microsoft Academic Search

Relativistic electrons moving into a highly tangled magnetic field emit jitter radiation. We present a detailed computation of the jitter radiation spectrum, including self-absorption, for electrons inside Weibel-like shock generated magnetic fields. We apply our results to the case of the prompt and afterglow emission of gamma-ray bursts. We show that jitter emission can reproduce most of the observed features

Jared C. Workman; Brian J. Morsony; Davide Lazzati; Mikhail V. Medvedev

2008-01-01

253

Jitter Radiation as a Possible Mechanism for Gamma-Ray Burst Afterglows: Spectra and Light Curves  

Microsoft Academic Search

The standard model of gamma-ray burst afterglows assumes that the radiation observed as a delayed emission is of synchrotron origin, which requires the shock magnetic field to be relatively homogeneous on small scales. An alternative mechanism-jitter radiation, which traditionally has been applied to the prompt emission-substitutes for synchrotron when the magnetic field is tangled on a microscopic scale. Such are

Mikhail V. Medvedev; Davide Lazzati; Brian C. Morsony; Jared C. Workman

2007-01-01

254

Jitter radiation in gamma-ray bursts and their afterglows: emission and self-absorption  

Microsoft Academic Search

Relativistic electrons moving into a highly tangled magnetic field emit\\u000ajitter radiation. We present a detailed computation of the jitter radiation\\u000aspectrum, including self-absorption, for electrons inside Weibel-like shock\\u000agenerated magnetic fields. We apply our results to the case of the prompt and\\u000aafterglow emission of gamma-ray bursts. We show that jitter emission can\\u000areproduce most of the observed features

Jared C. Workman; Brian J. Morsony; Davide Lazzati; Mikhail V. Medvedev

2007-01-01

255

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

Microsoft Academic Search

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

R. Zach; K. R. Mayoh

1982-01-01

256

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

NASA Astrophysics Data System (ADS)

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.

Plaza-Rosado, Heriberto

1991-09-01

257

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

NASA Technical Reports Server (NTRS)

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.

Plaza-Rosado, Heriberto

1991-01-01

258

Measurement of gamma radiation levels in soil samples from Thanjavur using gamma-ray spectrometry and estimation of population exposure.  

PubMed

This study assesses the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides (232)Th, (238)U and (40)K in 10 soil samples collected from Thanjavur (Tamil Nadu, India) using gamma-ray spectrometry. The activity profile of radionuclides has clearly showed the existence of low level activity in Thanjavur. The geometric mean activity concentrations of (232)Th, (238)U and (40)K is 42.9+/-9.4 Bq.kg(-1), 14.7+/-1.7 Bq.kg(-1) and 149.5+/-3.1 Bq.kg(-1) respectively are derived from all the soil samples studied. The activity concentration of (232)Th, (238)U and (40)K in soil is due to the presence of metamorphic rocks like shale, hornblende-biotite gneiss and quartzofeldspathic gneiss in these areas. Gamma absorbed dose rates in air outdoors were calculated to be in the range between 32 nGy.h(-1) and 59.1 nGy.h(-1) with an arithmetic mean of 43.3 +/-9 nGy.h(-1). This value is lesser than the population weighted world-averaged of 60 nGy.h(-1). Inhabitants of Thanjavur are subjected to external gamma radiation exposure (effective dose) ranging between 39.2 and 72.6 muSv.y(-1) with an arithmetic mean of 53.1+/-11 muSv.y(-1). The values of the external hazard index determined from the soil radioactivity of the study area are less than the recommended safe levels. PMID:20177570

Senthilkumar, B; Dhavamani, V; Ramkumar, S; Philominathan, P

2010-01-01

259

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

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

Saroj, Sunil; Shashidhar, R; Bandekar, Jayant

2009-10-01

260

Response of organic liquid scintillators to fast neutrons and gamma radiation  

NASA Astrophysics Data System (ADS)

Liquid organic scintillators are cocktails of aromatic fluorophores in an aromatic solvent. They find widespread use in Liquid Scintillation Counters with applications in medical diagnostics as well as fundamental nuclear and particle physics. Ultima Gold™ XR, a commercially available organic liquid scintillator from Perkin Elmer, can be used in both aqueous and non-aqueous systems and is typically used for beta detection in medical diagnostics. Its performance under gamma radiation and neutron radiation is less well-characterized. Special and normal Ultima Gold™ XR liquid scintillators were exposed in separate experiments to fast neutrons and high energy photons from a nuclear reactor and to gamma rays from a Co-60 source. To perform the measurements in the radiation chamber, a custom light collection system consisting of a fiber optic cable, spectrometer and a diffuse reflecting optical cavity was fabricated. Advanced calibration procedures, traceable to NIST standards, were developed to determine photon fluxes and flux densities of the scintillators under ionizing radiation conditions. The scintillator emission spectra under gamma radiation from a Co-60 source and neutron radiation from a pool-type nuclear reactor were recorded and compared. Results on the spectrometer design and comparison of the spectra under different exposure are presented.

Hoertz, Paul G.; Mills, Karmann; Davis, Lynn; Baldasaro, Nicholas; Gupta, Vijay

2013-03-01

261

Papain incorporated chitin dressings for wound debridement sterilized by gamma radiation  

NASA Astrophysics Data System (ADS)

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.

Singh, Durgeshwer; Singh, Rita

2012-11-01

262

High linear-energy-transfer radiation can overcome radioresistance of glioma stem-like cells to low linear-energy-transfer radiation  

PubMed Central

Ionizing radiation is applied as the standard treatment for glioblastoma multiforme (GBM). However, radiotherapy remains merely palliative, not curative, because of the existence of glioma stem cells (GSCs), which are regarded as highly radioresistant to low linear-energy-transfer (LET) photons. Here we analyzed whether or not high-LET particles can overcome the radioresistance of GSCs. Glioma stem-like cells (GSLCs) were induced from the GBM cell line A172 in stem cell culture medium. The phenotypes of GSLCs and wild-type cells were confirmed using stem cell markers. These cells were irradiated with 60Co gamma rays or reactor neutron beams. Under neutron-beam irradiation, high-LET proton particles can be produced through elastic scattering or nitrogen capture reaction. Radiosensitivity was assessed by a colony-forming assay, and the DNA double-strand breaks (DSBs) were assessed by a histone gamma-H2AX focus detection assay. In stem cell culture medium, GSLCs could form neurosphere-like cells and express neural stem cell markers (Sox2 and Musashi) abundantly in comparison with their parental cells. GSLCs were significantly more radioresistant to gamma rays than their parental cells, but neutron beams overcame this resistance. There were significantly fewer gamma-H2AX foci in the A172 GSLCs 24 h after irradiation with gamma rays than in their parental cultured cells, while there was no apparent difference following neutron-beam irradiation. High-LET radiation can overcome the radioresistance of GSLCs by producing unrepairable DNA DSBs. High-LET radiation therapy might have the potential to overcome GBM's resistance to X-rays in a clinical setting. PMID:23955054

Hirota, Yuki; Masunaga, Shin-Ichiro; Kondo, Natsuko; Kawabata, Shinji; Hirakawa, Hirokazu; Yajima, Hirohiko; Fujimori, Akira; Ono, Koji; Kuroiwa, Toshihiko; Miyatake, Shin-Ichi

2014-01-01

263

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

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

264

On the omnipresent background gamma radiation of the continuous spectrum  

E-print Network

The background spectrum of a germanium detector, shielded from the radiations arriving from the lower and open for the radiations arriving from the upper hemisphere is studied, both in a ground level and in an underground laboratory. It is established that the continuous portion of this background spectrum is mostly due to the radiations that arrive from the upper hemisphere of the continuous spectrum similar to the instrumental one. The intensity of this radiation of an average energy of about 120 keV is estimated to about 8000 photons/m2s 2\\pi srad in a ground level laboratory, and to about 5000 photons/m2s 2\\pi srad at the depth of 25 m.w.e. Rough estimates of the dose that it contributes to the skin are about 1.5 nSv/h and 1 nSv/h respectively. Simulations by GEANT4 and CORSIKA demonstrate that this radiation is both of cosmic and terrestrial origin, mixed in proportion that still has to be determined.

Banjanac, R; Jokovi?, D; Veselinovi?, N; Dragi?, A; Udovi?i?, V; Ani?in, I

2013-01-01

265

On the omnipresent background gamma radiation of the continuous spectrum  

E-print Network

The background spectrum of a germanium detector, shielded from the radiations arriving from the lower and open for the radiations arriving from the upper hemisphere is studied, both in a ground level and in an underground laboratory. It is established that the continuous portion of this background spectrum is mostly due to the radiations that arrive from the upper hemisphere of the continuous spectrum similar to the instrumental one. The intensity of this radiation of an average energy of about 120 keV is estimated to about 8000 photons/m2s 2\\pi srad in a ground level laboratory, and to about 5000 photons/m2s 2\\pi srad at the depth of 25 m.w.e. Rough estimates of the dose that it contributes to the skin are about 1.5 nSv/h and 1 nSv/h respectively. Simulations by GEANT4 and CORSIKA demonstrate that this radiation is both of cosmic and terrestrial origin, mixed in proportion that still has to be determined.

R. Banjanac; D. Maleti?; D. Jokovi?; N. Veselinovi?; A. Dragi?; V. Udovi?i?; I. Ani?in

2013-05-14

266

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...

267

Response of shortgrass plains vegetation to gamma radiation. I. Chronic irradiation  

Microsoft Academic Search

Native shortgrass plains vegetation was exposed to chronic gamma ; radiation with exposure rates varying from 0.01 to 650 R\\/hr starting in April ; 1969. The dominant species in the plant community was Bouteloua gracilis (blue ; grama). Density and frequency were recorded and these data were converted into ; community indices of coefficient of community (CC) and diversity (D).

L. Jr. Fraley; F. W. Whicker

1973-01-01

268

Microbiological, chemical, and sensory quality changes in Pico de gallo as affected by gamma radiation  

E-print Network

This study was undertaken to gain a greater understanding of the effects of gamma radiation and storage at 2'C on the microbiological, sensorial and chemical quality of pico de gallo. Samples of pico de gallo were exposed to cobalt'o at a dose of I...

Miller, Gerald Howard

1994-01-01

269

Effect of Gamma and UV Radiation on Properties of EPDM\\/GTR\\/HDPE Blends  

Microsoft Academic Search

Ethylene propylene dine monomer (EPDM) was blended with both ground tire rubber (GTR) and high-density polyethylene (HDPE) prepared at different ratios and then exposed to gamma and ultraviolet radiations. The mechanical, physical, and thermal properties were investigated with respect to the kind of irradiation and blend compositions. A scanning electron microscope was also used to examine the morphology of the

M. M. Abou Zeid; S. T. Rabie; A. A. Nada; A. M. Khalil; R. H. Hilal

2008-01-01

270

THE EFFECTS OF GAMMA RADIATION ON JPN PROPELLANT. Memorandum Report No. 122  

Microsoft Academic Search

Strips of JPN propellart were subjected to the gamma radiation of cobalt-; 60 sources at Brooknaven National Laboratory. These strips were chemically ; analyzed and physically tested. Significant changes were observed in the ; viscosity of the nitrocellulose, the available centralites and the stability of ; the propellant. The main transformation product of the ethyl centralitc ; stabilizer was 4-nitrocentralite.

A. Owyang; H. Rosenwasser

1956-01-01

271

MICRONUCLEI IN BINUCLEATED LYMPHOCYTES OF MICE FOLLOWING EXPOSURE TO GAMMA RADIATION  

EPA Science Inventory

Experiments were designed to investigate the induction of micronuclei (MN) in mouse peripheral blood lymphocytes (PBLs) after in vitro or in vivo exposure to 60Co gamma radiation. or the in vitro experiments, 4 ml of blood from male C57BL/6J mice were either irradiated in 6 ml Fa...

272

Radiation degradation and frictional properties of gamma sterilized PVC (copper-T)  

Microsoft Academic Search

Polyvinyl chloride (PVC) components used in medical devices as flanges may lose their frictional property on gamma sterilization due to radiation degradation. Frictional load, glass transition temperature, linear expansion coefficient, dynamic load expansion and specific heat measurements have been carried out on PVC flanges to investigate the effect of irradiation and formulations have been developed for eliminating the undesired effects.

L. Varshney; N. Balan; S. V. Choughule; P. K. Jothish; K. Krishnamurthy

1996-01-01

273

An Electronically-collimated Gamma-ray Detector for Localization of Radiation Sources  

Microsoft Academic Search

Small hand-held radiation detectors that can image a gamma-ray source and yet can be transported by a single operator could have numerous applications, either in medical intraoperative procedures or in nuclear security field work. We report on the design of a device intended for such applications and we present results of simulations that indicate expected performance for such a compact

Blair Smith; Kenneth L. Matthews II; Adam Lackie; W. H. Hill; Wei-Hsung Wang; M. L. Cherry

2006-01-01

274

Kinetics of the radiation-induced radicals in gamma irradiated solid cefazolin sodium  

Microsoft Academic Search

Room and high temperature kinetic and spectroscopic features of the radical species produced in gamma irradiated cefazolin sodium (here after CS) were investigated in detail using electron spin resonance (ESR) spectroscopy to determine the feasibility of its sterilization by radiation and to explore the dosimetric properties of this semi-synthetic representative of cephalosporins. Irradiated CS exhibits an unresolved ESR doublet as

S. Yurus; M. Korkmaz

2005-01-01

275

A simple detector for locating radiography and radiotherapy gamma emitting radiation sources  

Microsoft Academic Search

The author provides a simple design of collimated Geiger-Muller tube detector which is simple to construct and would be useful in the recovery of lost gamma radiation sources. The detector is compatible with the majority of ratemeters in present use.

P H Burgess

1983-01-01

276

Use of gamma radiation as a form of preservation of sweet potatoes  

NASA Astrophysics Data System (ADS)

The effects of (GAMMA) radiation on the sweet potato weevil, organoleptic properties of sweet potatoes, protein content of same, and sweet potato quality (vitamins, color, texture, and carbohydrates) are discussed. Evaluation of preliminary results indicate that changes should be made in irradiation procedures/conditions and analyses.

277

Gamma radiation effects on physical properties of parchment documents: Assessment of Dmax  

NASA Astrophysics Data System (ADS)

Parchments are important documents that give testimony for History; therefore these materials should be respected and preserved. Considering incremental biodeterioration problems that have to be faced daily, the Archive of the University of Coimbra (AUC) is involved in different scientific projects in order to evaluate and determine new methods for document decontamination and preservation. The aim of this study was to evaluate gamma radiation effects on the colour and texture of the AUC parchment documents. The assessment of these effects was used to estimate the maximum gamma radiation dose (Dmax) that could guarantee parchment documents' decontamination treatment, without significant alteration of their physical properties. Parchment samples were exposed to gamma radiation doses ranging from 10 to 30 kGy. The texture and colour of samples were assessed before and after the irradiation procedure, using a texture analyser and an electronic colorimeter. Hardness and springiness were determined based on texture spectra. Lightness (L*), Chroma (C), greenness vs. redness (a*) and yellowness vs. blueness (b*) values were obtained from colorimetric measures. Results indicate no significant effects of gamma radiation on the texture and colour of parchment for the studied doses.

Nunes, Inês; Mesquita, Nuno; Cabo Verde, Sandra; João Trigo, Maria; Ferreira, Armando; Manuela Carolino, Maria; Portugal, António; Luísa Botelho, Maria

2012-12-01

278

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

PubMed Central

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

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

279

Effect of SPE-like Proton or Photon Radiation on the Kinetics of Mouse Peripheral Blood Cells and Radiation Biological Effectiveness Determinations  

PubMed Central

Abstract Exploration missions outside low-Earth orbit are being planned; therefore, it is critical to understand the risk astronauts would be exposed to in the space environment, especially during extravehicular activities (EVAs). Reductions in white blood cell (WBC) numbers can occur as a result of exposure to solar particle event (SPE) radiation. The aim of the present study was to determine the duration of the effects on blood cell numbers from exposure to a single whole-body dose of SPE-like proton radiation or photon radiation as well as to determine the radiation biological effectiveness (RBE) values at those times when radiation exposure causes blood cell numbers to experience the most critical effects when using mice as a model. Our results indicate that both types of radiation cause significant reductions in the numbers of all blood cell types at different times post-irradiation. The RBE values were not significantly different from 1.0. These results indicate that the risk estimations for astronauts from exposure of mice to SPE-like proton radiation are comparable to those previously made for doses of standard reference radiations, suggesting that countermeasures should be developed for the decreases in blood cell counts observed following the exposure of mice to SPE radiation. Key Words: Proton radiation—Gamma radiation—Blood cell counts—Solar particle event. Astrobiology 13, 570–577. PMID:23980767

Romero-Weaver, A.L.; Wan, X.S.; Diffenderfer, E.S.; Lin, L.

2013-01-01

280

Actions of gamma-aminobutyric acid on sympathetic ganglion cells.  

PubMed Central

1. Responses of single ganglion cells in the isolated rat superior cervical ganglion to gamma-aminobutyric acid (GABA) applied via the bathing medium were recorded using intracellular micro-electrodes. 2. GABA produced a large fall in cell input resistance, frequently to immeasurable levels. In thirteen cells showing a modest response to 100 muM GABA, input resistance fell from 50-5 +/-9-5 to 15.9 +/- 3-2 Momega (means +/- S.E. of mean). After correction for resistance leaks introduced by the impaling electrode, the resting membrane resistance Rm and the resistance of the GABA-shunt Rg in these cells were calculated to be 79-3 +/- 16-6 and 35-0 +/- 9-5 Momega respectively. 3. Cells with recorded resting membrane potentials greater than -42 mV were depolarized by GABA; at resting potential less than -42 mV they were hyperpolarized... PMID:1177140

Adams, P R; Brown, D A

1975-01-01

281

Orbital Observatory GLAST - New Step in the Study of Cosmic Gamma Radiation: Mission Overview  

NASA Technical Reports Server (NTRS)

This viewgraph presentation is a overview of the Gamma-ray Large Area Space Telescope (GLAST), now named Fermi Space Telescope. The new telescope is scheduled for launch in the middle of 2008. It contains the high energy gamma-ray telescope LAT (Large Area Telescope) and the GMB (GLAST Burst Monitor). The science objectives of GLAST cover almost every area of high energy astrophysics, including Active Galactic Nuclei (AGN), including Extragalactic background light (EBL), Gamma-ray bursts (GRB), Pulsars, Diffuse gamma-radiation, EGRET unidentified sources, Solar physics, Origin of Cosmic Rays and, Dark Matter and New Physics. Also included in this overview is a discussion of the preparation to the analysis of the science data.

Moiseev, Alexander

2008-01-01

282

Radon flux maps for the Netherlands and Europe using terrestrial gamma radiation derived from soil radionuclides  

NASA Astrophysics Data System (ADS)

Naturally occurring radioactive noble gas, radon (222Rn) is a valuable tracer to study atmospheric processes and to validate global chemical transport models. However, the use of radon as a proxy in atmospheric and climate research is limited by the uncertainties in the magnitude and distribution of the radon flux density over the Earth's surface. Terrestrial gamma radiation is a useful proxy for generating radon flux maps. A previously reported radon flux map of Europe used terrestrial gamma radiation extracted from automated radiation monitoring networks. This approach failed to account for the influence of local artificial radiation sources around the detector, leading to under/over estimation of the reported radon flux values at different locations. We present an alternative approach based on soil radionuclides which enables us to generate accurate radon flux maps with good confidence. Firstly, we present a detailed comparison between the terrestrial gamma radiation obtained from the National Radiation Monitoring network of the Netherlands and the terrestrial gamma radiation calculated from soil radionuclides. Extending further, we generated radon flux maps of the Netherlands and Europe using our proposed approach. The modelled flux values for the Netherlands agree reasonably well with the two observed direct radon flux measurements (within 2? level). On the European scale, we find that the observed radon flux values are higher than our modelled values and we introduce a correction factor to account for this difference. Our approach discussed in this paper enables us to develop reliable and accurate radon flux maps in countries with little or no information on radon flux values.

Manohar, S. N.; Meijer, H. A. J.; Herber, M. A.

2013-12-01

283

Radiation measurement above the lunar surface by Kaguya gamma-ray spectrometer  

NASA Astrophysics Data System (ADS)

The lunar surface is filled with various ionizing radiations such as high energy galactic particles, albedo particles and secondary radiations of neutrons, gamma rays and other elementary particles. A high-resolution Kaguya Gamma-Ray Spectrometer (KGRS) was carried on the Japan’s lunar explorer SELENE (Kaguya), the largest lunar orbiter since the Apollo missions. The KGRS instrument employed, for the first time in lunar exploration, a high-purity Ge crystal to increase the identification capability of elemental gamma-ray lines. The Ge detector is surrounded by BGO and plastic counters as for anticoincidence shields. The KGRS measured gamma rays in the energy range from 200 keV to 13 MeV with high precision to determine the chemical composition of the lunar surface. It provided data on the abundance of major elements over the entire lunar surface. In addition to the gamma-ray observation by the KGRS, it successfully measured the global distribution of fast neutrons. In the energy spectra of gamma-rays observed by the KGRS, several saw-tooth- peaks of Ge are included, which are formed by the collision interaction of lunar fast neutrons with Ge atoms in the Ge crystal. With these saw-tooth-peaks analysis, global distribution of neutrons emitted from the lunara surface was successfully created, which was compared with the previous results obtained by Lunar Prospector neutron maps. Another anticoincidence counter, the plastic counter with 5 mm thickness, was used to veto radiation events mostly generated by charged particles. A single photomultiplier serves to count scintillation light from the plastic scintillation counter. The global map of counting rates observed by the plastic counter was also created, implying that the radiation counting rate implies the geological distribution, in spite that the plastic counter mostly measures high energy charged particles and energetic neutrons. These results are presented and discussed.

Hasebe, Nobuyuki; Nagaoka, Hiroshi; Kusano, Hiroki; Hareyama, Matoko; Ideguchi, Yusuke; Shimizu, Sota; Shibamura, Eido

284

Radiation degradation of solar cell arrays  

NASA Technical Reports Server (NTRS)

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.

Hill, C. W.

1975-01-01

285

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

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.

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

2010-12-22

286

The ultrastructure of radiation-induced endosteal myelofibrosis in the dog. [Gamma radiation  

SciTech Connect

A rapidly developing, progressive form of endosteal myelofibrosis (MF) (with myeloid metaplasia) has been shown to occur at low frequency (approximately 4%) in dogs exposed continuously to low daily doses (10 R/day) of whole-body gamma irradiation. We report in this study the morphological details of the endosteal surface during both preclinical and clinical phases of developing MF by combination light microscopy and scanning/transmission electron microscopy. Pronounced alterations of the endosteum were observed and included: (1) during the early preclinical phases, a progressive time-dependent transition of the endosteal surface from predominantly resting to actively formative and resorptive states; and (2) during the late preclinical phase, aberrant autonomous osteogenic process(es) characterized by a marked reduction in the resorptive, osteoclast-associated endosteal areas occurring concomitantly with further increases in formative areas of the endosteum. Localized patches of overlapping, morphologically transformed endosteal cells (i.e., round-osteoblastic to branched-reticular shaped) were observed within the morphologically reactive, formative endosteum. Osteogenic-endosteal changes coincided with major restructuring of the hematopoietic parenchyma and supporting stromal network. We discuss the possibility that the early occurring endosteal changes are causally linked to normal reparative functions that operate during regenerative hematopoiesis following local and systemic injury. Based on morphological data collected during the late preclinical phase, we speculate that the mechanism of myelofibrosis induction involves the failure to terminate early osteogenic-dependent repair sequences.

Seed, T.M.; Chubb, G.T.; Tolle, D.V.; Fritz, T.E.; Poole, C.M.; Doyle, D.E.; Lombard, L.S.; Kaspar, L.V.

1982-01-01

287

Radiative decay into $\\gamma P$ of the low lying axial-vector mesons  

E-print Network

We evaluate the radiative decay into a pseudoscalar meson and a photon of the whole set of the axial-vector mesons dynamically generated from the vector-pseudoscalar meson ($VP$) interaction. We take into account tree level and loop diagrams coming from the axial-vector decay into a vector and a pseudoscalar meson. We find a large span for the values of the radiative widths of the different axial-vector mesons. In particular, we evaluate the radiative decay into $K \\gamma$ of the two $K_1(1270)$ states, recently claimed theoretically, and discuss the experimental values quoted so far on the assumption of only one state.

Nagahiro, H; Oset, E

2008-01-01

288

Combined Effects of Gamma Radiation and High Dietary Iron on Peripheral Leukocyte Distribution and Function  

NASA Technical Reports Server (NTRS)

Both radiation and increased iron stores can independently increase oxidative damage, resulting in protein, lipid and DNA oxidation. Oxidative stress increases the risk of many health problems including cancer, cataracts, and heart disease. This study, a subset of a larger interdisciplinary investigation of the combined effect of iron overload on sensitivity to radiation injury, monitored immune parameters in the peripheral blood of rats subjected to gamma radiation, high dietary iron or both. Specific immune measures consisted of: (1) peripheral leukocyte distribution, (2) plasma cytokine levels and (3) cytokine production profiles following whole blood mitogenic stimulation

Crucian, Brian E.; Morgan, Jennifer L. L.; Quiriarte, Heather A.; Sams, Clarence F.; Smith, Scott M.; Zwart, Sara R.

2012-01-01

289

Inactivation of foodborne pathogens on seafood by gamma radiation  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ionizing radiation is used on a global basis to improve the phytosanitary and microbial safety and shelf-life of foods. In recent years progress has been made in the commercial application of irradiation to sterilize destructive invasive insects and to irradiate produce to improve its microbiologica...

290

The Effects of Ionizing Radiation on Mammalian Cells.  

ERIC Educational Resources Information Center

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)

Biaglow, John E.

1981-01-01

291

Response of oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), eggs to gamma radiation  

NASA Astrophysics Data System (ADS)

As insects increase in radiotolerance as they develop and usually several developmental stages of the pest may be present in the fresh shipped commodity, it is important to know the radiation susceptibility of the stages of the target insect before the establishment of ionizing radiation quarantine treatments. This study was performed to determine the radiotolerance of eggs of the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), to gamma radiation. This species is considered as one of the most serious worldwide pests for temperate fruits, especially peaches. Eggs (12 h old) were exposed to 0 (control), 25, 35, 50, 75, 100, 125 and 150 Gy of gamma radiation. Surviving larvae were allowed to feed on an artificial diet. Three days after irradiation, it was verified that larvae's cephalic capsules were significantly affected by gamma radiation, and the estimated mean LD 90 and LD 99 were 66.3 Gy and 125.8 Gy, respectively. Oriental fruit moth eggs revealed to be quite radiosensitive and very low doses as 50 Gy were sufficient to disrupt G. molesta embryogenesis. At 25 Gy, only male adults originated from the surviving larvae and, after mating with untreated fertile females, shown to be sterile.

Silva, W. D.; Arthur, V.; Mastrangelo, T.

2010-10-01

292

Effect of Gender on the Radiation Sensitivity of Murine Blood Cells.  

PubMed

Space travel beyond the Earth's protective magnetosphere risks exposing astronauts to ionizing radiation, such as that generated during a solar particle event (SPE). Ionizing radiation has well documented effects on blood cells and it is generally assumed that these effects contribute to the hematopoietic syndrome (HS), observed in animals and humans, following exposure to total body irradiation (TBI). The purpose of the current study was to assess the role of gender on the effects of gamma radiation on blood cells. C3H/HeN mice were irradiated with a (137)Cs gamma source. Radiation had similar effects on white blood cells (WBCs), lymphocytes, and granulocytes in male and female C3H/HeN mice, while red blood cell (RBC) counts and hematocrit values remained stable following radiation exposure. Non-irradiated male mice had 13% higher platelet counts, compared with their female counterparts, and showed enhanced recovery of platelets on day 16 following radiation exposure. Hence, gender differences influence the response of platelets to TBI exposure. PMID:25221782

Billings, Paul C; Romero-Weaver, Ana L; Kennedy, Ann R

2014-08-01

293

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

SciTech Connect

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.

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

1989-12-31

294

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

SciTech Connect

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.

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

1989-01-01

295

Polyaniline nanofilms as a monitoring label and dosimetric device for gamma radiation  

SciTech Connect

In this work, an optical dosimeter for gamma radiation ({sup 60}Co) based on the color change of polyaniline nanofilms in the emeraldine oxidation state was developed by spin coating of the polymer films on glass substrates. After irradiation, the nanofilms were characterized by UV-visible (UV-Vis) absorption spectroscopy as a function of the {sup 60}Co radiation dose. The deep blue color, characteristic of undoped polyaniline films before irradiation subsequently becomes green as the film is irradiated, and the film absorption coefficient exhibits a linear dependence with logarithm of the irradiation dose from 1 to 10 kGy. These results strongly suggest that polyaniline nanofilms can be used as a qualitative and quantitative dosimeter for gamma radiation in the analyzed dose range.

Laranjeira, J.M.G.; Khoury, H.J.; Azevedo, W.M. de; Vasconcelos, E.A. de; Silva, E.F. da

2003-03-15

296

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

NASA Astrophysics Data System (ADS)

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.

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

297

Prostaglandins can modify gamma-radiation and chemical induced cytotoxicity and genetic damage in vitro and in vivo  

SciTech Connect

The effect of prostaglandin E1, E2, and F2 alpha on gamma-radiation, benzo(a)pyrene and diphenylhydantoin-induced cytotoxicity in vivo and genotoxicity in vitro was investigated. Prostaglandin E1 prevented both cytotoxic and genotoxic actions of all the three agents, where as both PGE2 and PGF2 alpha were ineffective. In fact, it was seen that both PGE2 and PGF2 alpha are genotoxic by themselves. Gamma-linolenic acid and dihomogamma-linolenic acid, the precursor of PGE1 were also as protective as that of PGE1, where as arachidonic acid, the precursor of 2 series PGs, has genotoxic actions to human lymphocytes in vitro. These results suggest that prostaglandins and their precursors can determine the susceptibility of cells to cytotoxic and genotoxic actions of chemicals and radiation. This study is particularly interesting since, it is known that some tumor cells contain excess of PGE2 and PGF2 alpha and many carcinogens can augment the synthesis of 2 series of PGs.

Das, U.N.; Ramadevi, G.; Rao, K.P.; Rao, M.S. (Nizam's Institute of Medical Sciences, Hyderabad (India))

1989-12-01

298

Phorbol ester replacement of helper cell and interleukin 2 requirements in gamma interferon production.  

PubMed Central

Immune interferon (IFN-gamma) production by mitogen-stimulated C57BL/6 mouse spleen cells required both Lyt 1+,2- and Lyt 1-,2+ lymphocytes. The Lyt 1-,2+ cells were the IFN-gamma producers, whereas the Lyt 1+,2- cells were the helpers. Interleukin 2 mediated the Lyt 1+,2- cell help. Phorbol myristic acetate (10 ng/ml) completely replaced Lyt 1+,2- helper cell or interleukin 2 requirements in IFN-gamma production. The phorbol ester exerted its helper effects by direct interaction with IFN-gamma-producing Lyt 1-,2+ cells and not through stimulation of production of interleukin 2 by Lyt 1+, 2- cells. Suppressor cell effects in IFN-gamma production were also completely abrogated by phorbol myristic acetate. The data suggest a mechanism for phorbol myristic acetate regulation of IFN-gamma production at the cellular level. PMID:6178691

Johnson, H M; Torres, B A

1982-01-01

299

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

NASA Technical Reports Server (NTRS)

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.

Hada, Megumi; Cucinotta, Francis; Wu, Honglu

2009-01-01

300

THE PHOTOSPHERIC RADIATION MODEL FOR THE PROMPT EMISSION OF GAMMA-RAY BURSTS: INTERPRETING FOUR OBSERVED CORRELATIONS  

SciTech Connect

We show that the empirical E{sub p}-L, {Gamma}-L, E{sub p}-{Gamma}, and {eta}-bar{sub {gamma}}-E{sub p} correlations (where L is the time-averaged luminosity of the prompt emission, E{sub p} is the spectral peak energy, {Gamma} is the bulk Lorentz factor, and {eta}-bar{sub {gamma}} is the emission efficiency of gamma-ray bursts, GRBs) are well consistent with the relations between the analogous parameters predicted in the photospheric radiation model of the prompt emission of GRBs. The time-resolved thermal radiation of GRB 090902B does follow the E{sub p}-L and {Gamma}-L correlations. A reliable interpretation of the four correlations in alternative models is still lacking. These may point toward a photospheric origin of prompt emission of some GRBs.

Fan Yizhong; Wei Daming; Zhang Fuwen [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Zhang Binbin, E-mail: yzfan@pmo.ac.cn, E-mail: dmwei@pmo.ac.cn, E-mail: fwzhang@pmo.ac.cn, E-mail: bbzhang@psu.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

2012-08-10

301

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

NASA Astrophysics Data System (ADS)

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.

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

302

Effects of gamma radiation on Serratia marcescens; a comparison of effects of two different exposure rates  

E-print Network

EFFECTS OF GAMMA RADIATION ON SL'RNATIA MARCESCENS A COMPARISON OF EFFECTS OF TWO DIFFERENT EXPOSURE RATES A Thesis by CHRISTY ANNETTE MOORE Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirements...) Christy A. Moore, B, S, Northwestern State College Directed by: Dr. . R. D. Neff The survival curves of gamma-irradiated pigmenting and non- pigmcnting stzains of 'srz'rztia. mancssosns were determiz. ed using exposure rates of 175R/minute and 23, 520...

Moore, Christy Annette

1972-01-01

303

Dose rate assessment of terrestrial gamma radiation in the Delta region of Nigeria.  

PubMed

In situ gamma spectroscopy has been employed to characterise natural radiation in the soil at 32 locations in the Delta region of Nigeria. The outdoor gamma dose rates in the air due to 40K, 238U and 232Th in the soil were 1.5 +/- 0.9 nGy h(-1), 6.9 +/- 1.6 nGy h(-1) and 16.3 +/- 3.1 nGy h(-1) respectively. The estimated total annual outdoor effective dose to the people in the region was 31.6 microSv y(-1). PMID:14974607

Arogunjo, A M; Farai, I P; Fuwape, I A

2004-01-01

304

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

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

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

305

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

306

Dose quantities and instrumentation for measuring environmental gamma radiation during emergencies.  

PubMed

The dosimetry for exposure to gamma radiation in the environment is reviewed, including the factors used to convert measurements of traceable quantities to effective dose equivalent. A value of 0.70 Sv Gy-1 is widely used to convert air kerma or absorbed dose-to-air to effective dose equivalent, but recent work shows that a value of 0.86 Sv Gy-1 is more appropriate for deposited radionuclides. The arguments are reviewed and the implications of using operational dose equivalent quantities defined by the International Commission on Radiation Units and Measurements are considered. For planar deposited sources in the environment, it is shown that the use of ambient dose equivalent quantities without applying conversion factors, could significantly overestimate effective dose equivalent. In contrast, the adoption of the new effective dose quantity defined by the International Commission on Radiological Protection in Publication 60 will have a small impact on conversion factors for gamma radiation in the environment. Practical aspects of measurement are also considered, and five instruments suitable for measuring environmental gamma radiation have been evaluated in the laboratory and in field tests. The instruments include models with scintillation detectors, a Geiger-Müller detector, and a high-pressure ionization chamber, the choice being influenced by those commonly used in European Community countries for routine and emergency monitoring. The main disadvantage of all the instruments is the lack of spectral information, so a straightforward emergency instrument capable of discriminating between natural and artificial radionuclides has also been evaluated. PMID:8491600

Clark, M J; Burgess, P H; McClure, D R

1993-05-01

307

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

DOEpatents

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.

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

1987-02-27

308

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

DOEpatents

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.

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

1989-01-01

309

Assessment of health risk levels associated with terrestrial gamma radiation dose rates in Nigeria.  

PubMed

A decree on radiation safety and protection have been signed by the Federal Government of Nigeria that established a regulatory body to control the importation, application, transportation and disposal of radioactive materials in the environment. The fundamental function of the body is embodied on radiation protection of the country's population and the environment. However, the protection and assessment of any radiation pollution in the environment to a large extent is based on the knowledge of the baseline of radiation dose rate levels due to natural radionuclides. This study assesses the risks associated with terrestrial gamma radiation dose rate levels in some cities across the major geological formations of the country. Results showed that in the Northern region the number of individuals at risk of incurring cancer ranged between 0.25 and 3.25 yr with an average value of 1.46+/-0.45, while in the southwestern region it ranged between 0.76 and 5.50 yr(-1) with a mean value of 1.66+/-0.63 and in the southeastern region it was between 0.17 and 0.89 yr(-1) with a mean value of 0.35+/-0.14. Assuming uniform exposure for the entire population of 98.5 million, it has been estimated that about 160 individuals annually are at risk of incurring cancer due to exposure to terrestrial gamma radiation. PMID:11488386

Jibiri, N N

2001-07-01

310

Measurements of longitudinal gamma ray distribution using a multichannel fiber-optic Cerenkov radiation sensor  

NASA Astrophysics Data System (ADS)

Cerenkov radiation occurs when charged particles are moving faster than the speed of light in a transparent dielectric medium. In optical fibers, Cerenkov radiation can also be generated due to the fiber’s dielectric components. Accordingly, the radiation-induced light signals can be obtained using the optical fibers without any scintillating material. In this study, we fabricated a multichannel, fiber-optic Cerenkov radiation sensor (FOCRS) system using silica optical fibers (SOFs), plastic optical fibers (POFs), an optical spectrometer, multi-anode photomultiplier tubes (MA-PMTs) and a scanning system to measure the light intensities of Cerenkov radiation induced by gamma rays. To evaluate the fading effects in optical fibers, the spectra of Cerenkov radiation generated in the SOFs and POFs were measured based on the irradiation time by using an optical spectrometer. In addition, we measured the longitudinal distribution of gamma rays emitted from the cylindrical type Co-60 source by using MA-PMTs. The result was also compared with the distribution of the electron flux calculated by using the Monte Carlo N-particle transport code (MCNPX).

Shin, S. H.; Jeon, D.; Kim, J. S.; Jang, J. S.; Jang, K. W.; Yoo, W. J.; Moon, J. H.; Park, B. G.; Kim, S.; Lee, B.

2014-11-01

311

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

NASA Astrophysics Data System (ADS)

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.

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

1991-04-01

312

Evaluation of the in vivo genotoxic effects of gamma radiation on the peripheral blood leukocytes of head and neck cancer patients undergoing radiotherapy.  

PubMed

The present study aimed to evaluate the genotoxic effects of ionizing radiation on non-target cells of Head and Neck Squamous Cell Carcinoma (HNSCC) patients exposed to various cumulative doses of gamma rays during radiotherapy. The ten patients (P1-P10) were treated with cobalt 60 gamma radiation (External Beam Radiotherapy) for a period of five to six weeks with a daily fraction of 2Gy for 5 days each week. The genotoxic effects of radiation (single strand breaks - SSBs) in these patients were analyzed using the alkaline single cell gel electrophoresis (SCGE) technique, with the Olive Tail Moment (OTM) as the critical parameter. A sample of each patient's peripheral blood before starting with radiotherapy (pre-therapy) served as the control, and blood collected at weekly time intervals during the course of the radiotherapy served as treated (10, 20, 30, 40, 50 and 60Gy) samples. In vivo radiosensitivity of these patients, as indicated by SSB's after the cumulative radiation doses at the various times, was assessed using Student's t-test. Significant DNA damage relative to the individual patient's pre-therapy baseline data was observed in all patients. Inter-individual variation of the genotoxic effects was analyzed using two-way ANOVA. The correlation between doses for the means of smoker and non-smoker patients was calculated using the Pearson test. The results of this study may indicate the need to reduce the daily radiotherapy dose further to prevent genotoxic effects on non-target cells, thus improving safety. Furthermore, these results may indicate that the estimation of DNA damage following exposure to a gamma radiation, as measured by the comet assay in whole blood leukocytes, can be used to screen human populations for radiation-induced genetic damage at the molecular level. PMID:23370449

Kadam, Samit B; Shyama, Soorambail K; Almeida, Valentine G

2013-04-15

313

Increase in bacteriophage radiation resistance as a result of enhanced expression of stress systems in host cells  

SciTech Connect

By means of polyacrylamide gel electrophoresis (PAGE) of proteins from radiation-resistant Gam{sup r} mutants of Escherichia coli, it was shown that induction and elimination of RecA protein in these mutants are kinetically more rapid than in wild type cells, and heat-shock proteins (HSP) are hyperproduced even at a normal temperature (32{degrees}C). {gamma}- and UV-irradiated bacteriophages were used to study the results of simultaneous enhanced expression of two stress repair systems. Radiation-resistant mutants are similar to wild type cells in their ability to reactivate phages {Lambda}cI, {phi}80 vir, and T4D inactivated by {gamma}-rays and UV-light. W-reactivation of {gamma}-irradiated phages {Lambda} and {phi}80 is respectively 1.5 and 1.2 times higher in Gam{sup r} cells in which maximal W-reactivation was observed at wide range of doses (from 300 to 2000 Gy), whereas in wild type cells the peak C of W-reactivation was registered at doses of 400 to 450 Gy. The phage {Lambda}, {gamma}-irradiated upon adsorption on the cells of a radiation-resistant mutant, was two times more resistant to {gamma}-rays (DMF = 2 at LD{sub 10}) than when irradiated upon adsorption on wild type cells. Postirradiation degradation of the phage {Lambda} DNA, when irradiated within Gam{sup r} cells, was significantly lower than in wild type cells, and preirradiation of the cells decreased phage DNA degradation (12% in Gam{sup r} cells and 30% in wild-type cells). The role of an increased HSP level and expression of SOS-regulon in radiation resistance and possible interaction of stress systems in bacterial cells are discussed. 18 refs., 6 figs.

Verbenko, V.N.; Kalinin, V.L. [Konstantinov Inst. of Nuclear Physics, Gatchina (Russian Federation)

1995-12-01

314

A comparative study of gamma radiation effects on ultra-low input bias current linear circuits under biased conditions  

Microsoft Academic Search

Ultra-low input bias current linear circuits are used in several applications requiring them to work under varying conditions of temperature, humidity, radiation etc. which influence their performance. This paper presents a first time study of gamma radiation effects on ultra low input bias current linear circuits under biased conditions for small signal dc applications. Under biased conditions, radiation-induced photo currents

Vivek Agarwal; V. P. Sundarsingh; V. Ramachandran

2005-01-01

315

Mechanisms of linear energy transfer-dependent radiation resistance in myeloid leukemia cells  

NASA Astrophysics Data System (ADS)

Ionizing radiations (IRs) of high linear energy transfer (LET), such as alpha particles, produce fundamentally different forms of DNA damage in cells than conventional low LET radiation, such as gamma rays. Alpha particle therapies have recently emerged as important potential treatments of cancer, particularly for relatively easily-accessible malignancies of the hematopoietic system. Therefore, we created stable radioresistant myeloid leukemia HL60 cell clones derived after irradiation from either gamma rays (RG) or alpha particles (RA) in order to understand whether resistance to high LET (IR) was possible and the potential differences in radioresistance that could arise from radiations of different LET. Repeated irradiations yielded radioresistant HL60 clones and, regardless of derivation, displayed similar levels of resistance to IR of either type of radiation. The resistant phenotype in each type of radioresistant clone was driven by similar, multifactorial changes that included significant reductions in apoptosis, a decreased late G2/M checkpoint accumulation that was indicative of increased genomic instability, as well as more robust repair of specific types of DNA lesions that included DNA double-strand breaks (DSBs). The relative changes in resistance to alpha particles, however, were substantially lower than the increase in resistance to gamma rays. The data suggest that these processes were interdependent, as inhibition of homology directed repair in the resistant clones sensitized them to gamma IR to a larger extent than naive HL60 cells. Finally, we identified the downregulation of iron regulatory protein 1 (IRP1) in gamma-resistant cells but not in alpha-resistant cells. Short-hairpin RNA-mediated reductions in expression of IRP1 in radiation-naive HL60 cells led to significant radioresistance to gamma rays, but not alpha particles. The IRP1-mediated radioresistance was associated with changes in iron-mediated oxidative stress that led to significant reductions in IR-induced apoptosis and faster DNA repair, and appeared to be specific to cytotoxic agents dependent on oxidative-type stress. The data suggest that many similarities exist between radioresistant cells derived from fundamentally different types of IR, but that there are also LET-specific changes in cellular adaptation to repeated IR exposure. The data also underscore the potent cytotoxicity of alpha particles and warrant their continued investigation as cancer therapies.

Haro, Kurtis John

316

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

SciTech Connect

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.

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

1995-03-01

317

Single-cell analysis of T-cell receptor-gamma rearrangements in large-cell anaplastic lymphoma.  

PubMed

Large-cell anaplastic lymphomas (LCAL) are characterized by their distinctive morphology together with expression of the CD30 antigen. In addition, a chromosomal translocation, t(2;5) (p23; q35), can be detected in most cases. A significant proportion of LCALs carry rearrangements of the T-cell receptor-gamma (TCR-gamma) locus and display a T-cell phenotype. In about a third of the cases, another type of non-Hodgkin-lymphoma precedes LCAL. Early transformations of non-Hodgkin's lymphoma into LCAL might escape clinical detection in a significant number of cases. The existence of clonally related lymphoid cells within the lymph node infiltrates must be claimed in these cases. Recently, a small-cell-predominant variant of LCAL was described in which only few large tumor cells expressing the CD30 antigen are found together with numerous small lymphocytes, which are frequently CD30-. This observation in particular prompted us to investigate the clonal relationship of the tumor cell compartment and admixed small lymphocytes in one case of common LCAL with T-cell genotype. For this purpose, we chose to amplify rearranged TCR-gamma sequences from single cells isolated from immunostained frozen sections by using a micromanipulator. A total of 119 cells were investigated. Amplification products were obtained in 17 of 79 CD3+ cells, 12 of 30 CD30+ cells, and three of 10 CD20+ cells. The nucleotide sequences were determined in 28 cells by nonradioactive sequencing. In 11 CD30+ cells, the predominant rearrangement of TCR-gamma was identified. No clonal diversity was observed. The small CD3+ lymphocytes were unrelated to the anaplastic CD30+ tumor cells. This report describes a method to analyze rearrangements of the TCR-gamma in single cells isolated from immunostained frozen sections. Application of this technique revealed an absence of clonal diversity in a case of LCAL and documented the polyclonal nature of admixed small CD3+ lymphocytes. PMID:8919540

Lorenzen, J; Wintzer, C; Zhao-Hohn, M; Simons, G; Klockner, A; Fischer, R; Hansmann, M L

1996-03-01

318

Performance of neutron and gamma personnel dosimetry in mixed radiation fields  

SciTech Connect

From 1974 to 1980, six personnel dosimetry intercomparison studies (PDIS) were conducted at the Oak Ridge National Laboratory (ORNL) to evaluate the performance of personnel dosimeters in a variety of neutron and gamma fields produced by operating the Health Physics Research Reactor (HPRR) in the steady state mode with and without spectral modifying shields. A total of 58 different organizations participated in these studies which produced approximately 2000 measurements of neutron and gamma dose equivalents on anthropomorphic phantoms for five different reactor spectra. Based on these data, the relative performance of three basic types of neutron dosimeters (nuclear emulsion film, thermoluminescent (TLD), and track-etch) and two basic types of gamma dosimeters (film and TLD) in mixed radiation fields was assessed.

Swaja, R.E.; Sims, C.S.

1981-01-01

319

Gamma radiation effects on phenolics, antioxidants activity and in vitro digestion of pistachio ( Pistachia vera) hull  

NASA Astrophysics Data System (ADS)

The effect of gamma radiation (10, 20, 30, 40, 50 and 60 kGy) on tannin, total phenolics, antioxidants activity and in vitro digestion of pistachio hulls has been investigated in this study. The possibility of using the radial diffusion method based on software measurement of the rings area has also been investigated in this study. The software based method in radial diffusion method showed a higher r2 (0.995) value when compared to the traditional method. Irradiation reduced the tannin content ( P<0.01) and activity of antioxidants ( P<0.05) of pistachio hull extracts but increased the total phenolic content ( P<0.05). There was no effect of gamma irradiation on the in vitro digestion of the pistachio hull. Irradiation decreased the digestion rate of the pistachio hull at the dose of 40 kGy when compared to the control. This study showed that gamma irradiation decreased tannin and antioxidants activity of pistachio hull.

Behgar, M.; Ghasemi, S.; Naserian, A.; Borzoie, A.; Fatollahi, H.

2011-09-01

320

Gamma linolenic acid regulates gap junction communication in endothelial cells and their interaction with tumour cells  

Microsoft Academic Search

Tumour-endothelial cell adhesion forms a key role in the establishment of distant metastases. This study examined the effect of gamma linolenic acid (GLA), an anti-cancer polyunsaturated fatty acid (PUFA), on both the gap junction communication of human vascular endothelial cells and tumour cell-endothelial interactions. By using scrape loading of Lucifer yellow dye, we showed that GLA at non-toxic levels increased

W. G. Jiang; R. P. Bryce; R. E. Mansel

1997-01-01

321

On the Nature of Nonthermal Radiation from Cosmological Gamma-Ray Bursters  

E-print Network

Relativistic electron-positron winds with strong magnetic fields are considered as a source of radiation for cosmological $\\gamma$-ray bursters. Such a wind is generated by a millisecond pulsar with a very strong magnetic field. An electron-positron plasma near the pulsar is optically thick and in quasi-thermodynamic equilibrium. It is shown that the main part of radiation from the pulsar wind is nonthermal and generates in the following way. Kinetic energy which is released in the process of deceleration of the neutron star rotation transforms mainly to the magnetic field energy. The magnetic field is frozen in the outflowing plasma if the distance to the pulsar is smaller than $\\sim 10^{13}$ cm. This field transfers the energy from the pulsar environment to the region outside the $\\gamma$-ray photosphere of the electron-positron wind. At a distance of more than $\\sim 10^{13}$ cm the magnetohydrodynamic approximation for the pulsar wind is broken, and intense electromagnetic waves are generated. The frequency of these waves is equal to the frequency of the pulsar rotation. Outflowing particles are accelerated in the field of intense electromagnetic waves to Lorentz factors of the order of $10^6$ and generate nonthermal synchro-Compton radiation. The typical energy of nonthermal photons is $\\sim 1$ MeV. A high-energy tail of the $\\gamma$-ray spectrum may be up to $\\sim 10^4$ MeV. Baryonic matter is ejected occasionally from the pulsar magnetosphere. The baryonic matter ejection and subsequent suppression of the $\\gamma$-ray emission may be responsible for the time structure of $\\gamma$-ray bursts.

Vladimir V. Usov

1993-12-13

322

Somatic aberration induction in Tradescantia occidentalis by neutrons, x- and gamma-radiations. I. Dosimetry.  

PubMed

The dosimetry is described for an investigation of the induction of somatic aberrations in Tradescantia occidentalis by substantially mono-energetic neutrons in the energy range 100 keV to 15 MeV, by 200 keV X-rays and cobalt-60 gamma-radiation. Spectrometry was carried out for both neutrons and X-rays. Neutron fluence was measured by uranium fission chambers. Two types of ionization chamber were employed for dose measurement. One chamber was manufactured of CH-plastic and filled with acetylene and the other of graphite and filled with carbon dioxide. Dosimetry for X- and gamma-radiation was by means of lithium fluoride thermoluminescent dosemeters calibrated against a Victoreen ionization chamber. PMID:1084865

Dennis, J A; Delafield, H J; Peaple, L H; Boot, S J

1976-04-01

323

PHOTOSPHERIC EMISSION AS THE DOMINANT RADIATION MECHANISM IN LONG-DURATION GAMMA-RAY BURSTS  

SciTech Connect

We present the results of a set of numerical simulations of long-duration gamma-ray burst jets associated with massive, compact stellar progenitors. The simulations extend to large radii and allow us to locate the region in which the peak frequency of the advected radiation is set before the radiation is released at the photosphere. Light curves and spectra are calculated for different viewing angles as well as different progenitor structures and jet properties. We find that the radiation released at the photosphere of matter-dominated jets is able to reproduce the observed Amati and energy-Lorentz factor correlations. Our simulations also predict a correlation between the burst energy and the radiative efficiency of the prompt phase, consistent with observations.

Lazzati, Davide [Department of Physics, NC State University, 2401 Stinson Drive, Raleigh, NC 27695-8202 (United States); Morsony, Brian J. [Department of Astronomy, University of Wisconsin-Madison, 3321 Sterling Hall, 475 N. Charter Street, Madison WI 53706-1582 (United States); Margutti, Raffaella [Harvard-Smithsonian Center for Astrophysics, ITC, 60 Garden Street, Cambridge, MA 02138 (United States); Begelman, Mitchell C. [JILA, University of Colorado and National Institute of Standards and Technology, Boulder, CO 80309-0440 (United States)

2013-03-10

324

Jitter radiation in gamma-ray bursts and their afterglows: emission and self-absorption  

E-print Network

Relativistic electrons moving into a highly tangled magnetic field emit jitter radiation. We present a detailed computation of the jitter radiation spectrum, including self-absorption, for electrons inside Weibel-like shock generated magnetic fields. We apply our results to the case of the prompt and afterglow emission of gamma-ray bursts. We show that jitter emission can reproduce most of the observed features with some important differences with respect to standard synchrotron, especially in the frequency range between the self-absorption and the peak frequency. We discuss the similarities and differences between jitter and synchrotron and discuss experiments that can disentangle the two mechanisms.

Jared Workman; Brian Morsony; Davide Lazzati; Mikhail Medvedev

2008-01-23

325

Jitter radiation in gamma-ray bursts and their afterglows: emission and self-absorption  

E-print Network

Relativistic electrons moving into a highly tangled magnetic field emit jitter radiation. We present a detailed computation of the jitter radiation spectrum for electrons inside Weibel shock generated magnetic fields, including self-absorption. We apply our results to the case of the prompt and afterglow emission of gamma-ray bursts. We show that jitter emission can reproduce most of the observed features with some important differences with respect to standard synchrotron, especially between the self-absorption and the peak frequencies. We discuss the similarities and differences between jitter and synchrotron and discusss experiments that can disentangle the two mechanisms.

Workman, J; Lazzati, D; Medvedev, M; Workman, Jared; Morsony, Brian; Lazzati, Davide; Medvedev, Mikhail

2007-01-01

326

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

327

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

Microsoft Academic Search

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

R. Zach; K. R. Mayoh

1982-01-01

328

Gamma-radiation-induced wood-plastic composites from Syrian tree species  

NASA Astrophysics Data System (ADS)

Wood-plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, using three monomer systems; acrylamide, butylmethacrylate, and styrene, with methanol as the swelling solvent. Polymerization was induced at various radiation doses (10, 20, and 30 kGy) at a dose rate of 3.5 kGy/h using a 60Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength have been measured. The polymer loading decreases approximately with increasing density of the wood species used.

Bakraji, Elias Hanna; Salman, Numan; Al-kassiri, Haroun

2001-05-01

329

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

DOEpatents

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.

Condreva, K.J.

1997-01-14

330

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

DOEpatents

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.

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

1997-01-01

331

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

PubMed

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

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

2011-01-01

332

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

SciTech Connect

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.

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

333

Comparison of proton microbeam and gamma irradiation for the radiation hardness testing of silicon PIN diodes  

NASA Astrophysics Data System (ADS)

Simple and cost-effective solutions using Si PIN diodes as detectors are presently utilized in various radiation-related applications in which excessive exposure to radiation degrades their charge transport properties. One of the conventional methods for the radiation hardness testing of such devices is time-consuming irradiation with electron beam or gamma-ray irradiation facilities, high-energy proton accelerators, or with neutrons from research reactors. Recently, for the purpose of radiation hardness testing, a much faster nuclear microprobe based approach utilizing proton irradiation has been developed. To compare the two different irradiation techniques, silicon PIN diodes have been irradiated with a Co-60 gamma radiation source and with a 6 MeV proton microbeam. The signal degradation in the silicon PIN diodes for both irradiation conditions has been probed by the IBIC (ion beam induced charge) technique, which can precisely monitor changes in charge collection efficiency. The results presented are reviewed on the basis of displacement damage calculations and NIEL (non-ionizing energy loss) concept.

Jakši?, M.; Grilj, V.; Skukan, N.; Majer, M.; Jung, H. K.; Kim, J. Y.; Lee, N. H.

2013-09-01

334

Buildup factors of gamma rays including Bremsstrahlung and annihilation radiation for water, concrete, iron, and lead  

Microsoft Academic Search

Gamma-ray exposure buildup factors are calculated using a discrete ordinates direct integration code, PALLAS-PL, SP-Br, for water, concrete, iron, and lead, typifying materials of low, medium, and high atomic number. The radiation sources considered were both plane, at normal incidence, and at plane-isotropic. These data include the effects of secondary photon sources arising from Compton scattering, bremsstrahlung, and annihilation. Inclusion

K. Takeuchi; S. I. Tanaka

1984-01-01

335

Gamma ray bursts may be blueshifted bundles of the relic radiation  

E-print Network

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 \

Andrzej Krasi?ski

2015-02-02

336

Gamma ray bursts may be blueshifted bundles of the relic radiation  

E-print Network

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 \

Krasi?ski, Andrzej

2015-01-01

337

An Analysis of a Spreader Bar Crane Mounted Gamma-Ray Radiation Detection System  

E-print Network

AN ANALYSIS OF A SPREADER BAR CRANE MOUNTED GAMMA-RAY RADIATION DETECTION SYSTEM A Dissertation by MATTHEW DAVID GRYPP Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... sponsor for all the military required of me. Gentry Hearn created the software package and the post-processing Perl scripts that allowed both the collection and easy analysis of data. Jimmy Uhlemeyer has been my classmate in many courses and has been...

Grypp, Matthew D

2013-04-08

338

Gamma Knife radiosurgery for meningiomas: four cases of radiation-induced edema.  

PubMed

We review 48 cases of meningioma treated with Gamma Knife radiosurgery. The mean marginal dose was 15 Gy and the mean follow-up was 12 months. Follow-up computed tomography and magnetic resonance imaging showed tumor shrinkage in 19 cases, central necrosis in 1 case, loss of contrast enhancement in 1 case, and no change in 27 cases. We noted 4 cases of radiation-induced edema in supratentorial meningiomas. PMID:9032855

Nakamura, S; Hiyama, H; Arai, K; Nakaya, K; Sato, H; Hayashi, M; Kawamata, T; Izawa, M; Takakura, K

1996-01-01

339

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

Microsoft Academic Search

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

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

2003-01-01

340

Swelling characteristics and application of gamma-radiation on irradiated SBR-carboxymethylcellulose (CMC) blends  

Microsoft Academic Search

Blends of styrene butadiene rubber (SBR) with varying loading degree from 60wt% to 100wt% of carboxymethylcellulose (CMC) have been prepared. Gamma radiation vulcanization of prepared blends was carried out with doses varying between 50kGy and 250kGy. Mechanical properties, namely, tensile strength (Ts), elongation at break (Eb) and hardness were followed up as a function of loading degree of CMC and

Maysa A. Mohamed

341

Space solar cells: High efficiency and radiation damage  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

342

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

SciTech Connect

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.

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

1982-02-01

343

New decay branches of the radiative capture reaction {sup 12}C({sup 16}O,{gamma}){sup 28}Si  

SciTech Connect

Resonances in the {sup 12}C({sup 16}O,{gamma}){sup 28}Si radiative capture process at energies around the Coulomb barrier have been probed using the very selective 0 deg. Dragon spectrometer at Triumf and its associated BGO {gamma}-array. For the first time the full level scheme involved in this process has been measured and shows previously unobserved {gamma}-decay to doorway states around 11 MeV in {sup 28}Si.

Lebhertz, D.; Courtin, S.; Haas, F.; Salsac, M.-D.; Beck, C.; Michalon, A.; Rousseau, M. [IPHC, Universite Louis Pasteur, CNRS-IN2P3, Strasbourg (France); Marley, P. L.; Glover, R. G.; Kent, P. E. [University of York, York (United Kingdom); Hutcheon, D. A.; Davis, C.; Pearson, J. E. [TRIUMF, Vancouver (Canada)

2009-01-28

344

Some problems of extracting level density and radiative strength functions from the gamma-spectra in nuclear reactions  

E-print Network

The most important systematical errors in determination of level density and radiative strength functions for deformed nuclei have been estimated from the gamma-ray spectra in nuclear reactions like the stripping or pickup reactions.

V. A. Khitrov; A. M. Sukhovoj; Pham Dinh Khang; Vo Thi Anh; Vuong Huu Tan; Nguyen Canh Hai; Nguyen Xuan Hai

2003-05-13

345

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

SciTech Connect

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.

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

346

Cell death (apoptosis) in mouse intestine after continuous irradiation with gamma rays and with beta rays from tritiated water  

SciTech Connect

Apoptosis is a pattern of cell death involving nuclear pycnosis, cytoplasmic condensation, and karyorrhexis. Apoptosis induced by continuous irradiation with gamma rays (externally given by a 137Cs source) or with beta rays (from tritiated water injected ip) was quantified in the crypts of two portions of mouse bowel, the small intestine and descending colon. The time-course change in the incidence of apoptosis after each type of radiation could be explained on the basis of the innate circadian rhythm of the cells susceptible to apoptotic death and of the excretion of tritiated water (HTO) from the body. For 6-h continuous gamma irradiation at various dose rates (0.6-480 mGy/h) and for 6 h after injection of HTO of various radioactivities (0.15-150 GBq per kg body wt), the relationships between dose and incidence of apoptosis were obtained. Survival curves were then constructed from the curves for dose vs incidence of apoptosis. For the calculation of the absorbed dose from HTO, the water content both of the mouse body and of the cells was assumed to be 70%. One megabecquerel of HTO per mouse (i.e., 40 MBq/kg body wt) gave a dose rate of 0.131 mGy/h. The mean lethal doses (D0) were calculated for gamma rays and HTO, and relative biological effectiveness values of HTO relative to gamma rays were obtained. The D0 values for continuous irradiation with gamma rays were 210 mGy for small intestine and 380 mGy for descending colon, and the respective values for HTO were 130 and 280 mGy, indicating the high radiosensitivity of target cells for apoptotic death. The relative biological effectiveness of HTO relative to 137Cs gamma rays for cell killing in both the small intestine and the descending colon in the mouse was 1.4-2.1.

Ijiri, K.

1989-04-01

347

Celestial diffuse gamma radiation above 30 MeV observed by SAS-2  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

348

Branching Fractions and CP-Violating Asymmetries in Radiative B Decays to eta K gamma  

SciTech Connect

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.

Aubert, B.

2008-05-14

349

Measurement of Kp radiative capture to gammaLambda and gammaSigma0 for pK between 514 and 750 MeV\\/c  

Microsoft Academic Search

Differential cross sections for K- radiative capture in flight on the proton, leading to the gammaLambda and gammaSigma0 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

S. Prakhov; P. Vancraeyveld; N. Phaisangittisakul; B. M. K. Nefkens; V. Bekrenev; W. J. Briscoe; L. de Cruz; D. Isenhower; N. Knecht; A. Koulbardis; N. Kozlenko; S. Kruglov; G. Lolos; I. Lopatin; A. Marusic; S. McDonald; Z. Papandreou; D. Peaslee; J. W. Price; J. Ryckebusch; M. Sadler; A. Shafi; A. Starostin; H. M. Staudenmaier; I. I. Strakovsky; I. Supek; T. van Cauteren

2010-01-01

350

High efficiency, radiation-hard solar cells  

SciTech Connect

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.

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

2004-10-22

351

RADIATION SENSITIVITY AND QUALITY OF FRESH-CUT VEGETABLES EXPOSED TO GAMMA RADIATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thirteen fresh-cut (minimally processed) vegetables (broccoli, cilantro, red cabbage, endive, parsley, green and red leaf lettuce, Iceberg and Romaine lettuce, spinach, carrots, green onions, and celery) plus alfalfa sprouts were gamma irradiated at doses up to 3 kGy at 0.5 kGy intervals. The sample...

352

A human esophageal epithelial cell model for study of radiation induced cancer and DNA repair  

NASA Astrophysics Data System (ADS)

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.

Huff, Janice; Patel, Zarana; Hada, Megumi; Cucinotta, Francis A.

353

Radiation exposure induces inflammasome pathway activation in immune cells.  

PubMed

Radiation exposure induces cell and tissue damage, causing local and systemic inflammatory responses. Because the inflammasome pathway is triggered by cell death and danger-associated molecular patterns, we hypothesized that the inflammasome may signal acute and chronic immune responses to radiation. Using a mouse radiation model, we show that radiation induces a dose-dependent increase in inflammasome activation in macrophages, dendritic cells, NK cells, T cells, and B cells as judged by cleaved caspase-1 detection in cells. Time course analysis showed the appearance of cleaved caspase-1 in cells by day 1 and sustained expression until day 7 after radiation. Also, cells showing inflammasome activation coexpressed the cell surface apoptosis marker annexin V. The role of caspase-1 as a trigger for hematopoietic cell losses after radiation was studied in caspase-1(-/-) mice. We found less radiation-induced cell apoptosis and immune cell loss in caspase-1(-/-) mice than in control mice. Next, we tested whether uric acid might mediate inflammasome activation in cells by treating mice with allopurinol and discovered that allopurinol treatment completely blocked caspase-1 activation in cells. Finally, we demonstrate that radiation-induced caspase-1 activation occurs by a Nod-like receptor family protein 3-independent mechanism because radiation-exposed Nlrp3(-/-) mice showed caspase-1 activation profiles that were indistinguishable from those of wild-type mice. In summary, our data demonstrate that inflammasome activation occurs in many immune cell types following radiation exposure and that allopurinol prevented radiation-induced inflammasome activation. These results suggest that targeting the inflammasome may help control radiation-induced inflammation. PMID:25539818

Stoecklein, Veit M; Osuka, Akinori; Ishikawa, Shizu; Lederer, Madeline R; Wanke-Jellinek, Lorenz; Lederer, James A

2015-02-01

354

A technique for measuring gamma heating in a low fluence mixed radiation field  

SciTech Connect

Gamma heating measurements have been made in a low-Z lattice irradiated with 14-MeV neutrons and (n,n{prime}) gammas produced by a Texas Nuclear Model 9400 neutron generator. Heating measurements were made in the mid-line of the assembly using a proportional counter operating in the Continuously-varied Bias-voltage Acquisition mode. The neutron-induced signal was separated from the gamma-induced signal by exploiting the signal rise-time rate differences inherent to radiations of different Linear Energy Transfer, which are observable in a proportional counter. The operating limits of this signal separation technique were explored by observing the effect on the signal as the neutron spectrum is shifted from a D-T spectrum to a softer though still fast neutron spectrum as the counter is placed further into the irradiation lattice. The experiment was modelled using the one-dimensional radiation transport code ANISN/PC. The cross-section set used for these calculations was derived from the ENDF/B-V library using the code MC{sup 2}-2 for the case of D-T neutrons slowing down in a low-Z lattice. The calculated neutron and gamma spectra in the slab and the relevant mass-stopping powers were used to construct weighting factors which relate the energy deposition in the counter fill-gas to that in the counter wall and in the surrounding material. The total energy deposition at various positions in the lattice is estimated by applying these weighting factors to the measured gamma energy deposition in the counter at those locations. The overall utility of this measurement technique for fusion blanket neutronics is discussed. 8 refs., 5 figs., 2 tabs.

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

1991-01-01

355

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

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.

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

1985-10-01

356

Effects of acute gamma radiation on the reproductive ability of the earthworm Eisenia fetida.  

PubMed

Earthworms are the most suitable biological indicators of radioactive pollution because they are the parts of nutritional webs, and are present in relatively high numbers. Four months old Eisenia fetida were exposed to different doses of gamma radiation, namely 1, 2, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 & 60 Gy to study the effects of radiation on different reproductive parameters. The number of cocoons laid and the hatchlings emerged were recorded for all the selected doses. There was no reduction in cocoon production, however; decreasing size and weight of the cocoons was observed from the samples exposed to 20 Gy and above doses. Significant reductions in the hatchlings were recorded in earthworms exposed to 10 Gy and above doses. The dose response curves for a percentage reduction in hatchlings were constructed. Exposure to radiation dose of 1 and 2 Gy did not show any reduction, however, there was ?10%, ?50% and ?90% decrease in the hatchlings in samples exposed to 3, 15 and 45, 50, 55 and 60 Gy doses respectively. Delayed hatchability was also reported at al exposure level. Histology of irradiated earthworms revealed that the structural damage in the seminal vesicles was prominent at the exposed dose of 3 Gy onwards with complete degeneration on exposure to 60 Gy of gamma radiation. PMID:25461510

Sowmithra, K; Shetty, N J; Harini, B P; Jha, S K; Chaubey, R C

2015-02-01

357

Biological radiation dose from secondary particles in a Milky Way gamma-ray burst  

NASA Astrophysics Data System (ADS)

Gamma-ray bursts (GRBs) are a class of highly energetic explosions emitting radiation in a very short timescale of a few seconds and with a very narrow opening angle. Although, all GRBs observed so far are extragalactic in origin, there is a high probability of a GRB of galactic origin beaming towards the Earth in the past ~0.5 Gyr. We define the level of catastrophic damage to the biosphere as approximation 100 kJ m-2, based on Thomas et al. (2005a, b). Using results in Melott & Thomas (2011), we estimate the probability of the Earth receiving this fluence from a GRB of any type, as 87% during the last 500 Myr. Such an intense burst of gamma rays would ionize the atmosphere and deplete the ozone (O3) layer. With depleted O3, there will be an increased flux of Solar UVB on the Earth's surface with potentially harmful biological effects. In addition to the atmospheric damage, secondary particles produced by gamma ray-induced showers will reach the surface. Among all secondary particles, muons dominate the ground-level secondary particle flux (99% of the total number of particles) and are potentially of biological significance. Using the Monte Carlo simulation code CORSIKA, we modelled the air showers produced by gamma-ray primaries up to 100 GeV. We found that the number of muons produced by the electromagnetic component of hypothetical galactic GRBs significantly increases the total muon flux. However, since the muon production efficiency is extremely low for photon energies below 100 GeV, and because GRBs radiate strongly for only a very short time, we find that the biological radiation dose from secondary muons is negligible. The main mechanism of biological damage from GRBs is through Solar UVB irradiation from the loss of O3 in the upper atmosphere.

Atri, Dimitra; Melott, Adrian L.; Karam, Andrew

2014-07-01

358

Induced ICER I{gamma} down-regulates cyclin A expression and cell proliferation in insulin-producing {beta} cells  

SciTech Connect

We have previously found that cyclin A expression is markedly reduced in pancreatic {beta}-cells by cell-specific overexpression of repressor inducible cyclic AMP early repressor (ICER I{gamma}) in transgenic mice. Here we further examined regulatory effects of ICER I{gamma} on cyclin A gene expression using Min6 cells, an insulin-producing cell line. The cyclin A promoter luciferase assay showed that ICER I{gamma} directly repressed cyclin A gene transcription. In addition, upon ICER I{gamma} overexpression, cyclin A mRNA levels markedly decreased, thereby confirming an inhibitory effect of ICER I{gamma} on cyclin A expression. Suppression of cyclin A results in inhibition of BrdU incorporation. Under normal culture conditions endogenous cyclin A is abundant in these cells, whereas ICER is hardly detectable. However, serum starvation of Min6 cells induces ICER I{gamma} expression with a concomitant very low expression level of cyclin A. Cyclin A protein is not expressed unless the cells are in active DNA replication. These results indicate a potentially important anti-proliferative effect of ICER I{gamma} in pancreatic {beta} cells. Since ICER I{gamma} is greatly increased in diabetes as well as in FFA- or high glucose-treated islets, this effect may in part exacerbate diabetes by limiting {beta}-cell proliferation.

Inada, Akari [Section of Islet Transplantation and Cell Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215 (United States); Weir, Gordon C. [Section of Islet Transplantation and Cell Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215 (United States); Bonner-Weir, Susan [Section of Islet Transplantation and Cell Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215 (United States)]. E-mail: susan.bonner-weir@joslin.harvard.edu

2005-04-15

359

Neurotoxicity of human neural cells induced by space radiation: in vitro risk assessment and countermeasure  

NASA Astrophysics Data System (ADS)

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

Guida, P.; Vazquez, M.; Kim, A.

360

Group IVC cytosolic phospholipase A2gamma is farnesylated and palmitoylated in mammalian cells.  

PubMed

Cytosolic phospholipase A(2)gamma (cPLA(2)gamma) is a member of the group IV family of intracellular phospholipase A(2) enzymes, but unlike the well-studied cPLA(2)alpha, it is constitutively bound to membrane and is calcium independent. cPLA(2)gamma contains a C-terminal CaaX sequence and is radiolabeled by mevalonic acid when expressed in cPLA(2)alpha-deficient immortalized lung fibroblasts (IMLF(-/-)). The radiolabel associated with cPLA(2)gamma was identified as the farnesyl group. The protein farnesyltransferase inhibitor BMS-214662 prevented the incorporation of [(3)H]mevalonic acid into cPLA(2)gamma and partially suppressed serum-stimulated arachidonic acid release from IMLF(-/-) and undifferentiated human skeletal muscle (SkMc) cells overexpressing cPLA(2)gamma, but not from cells overexpressing cPLA(2)alpha. However, BMS-214662 did not alter the amount of cPLA(2)gamma associated with membrane. These results were consistent in COS cells expressing the C538S cPLA(2)gamma prenylation mutant. cPLA(2)gamma also contains a classic myristoylation site and several potential palmitoylation sites and was found to be acylated with oleic and palmitic acids but not myristoylated. Immunofluorescence microscopy revealed that cPLA(2)gamma is associated with mitochondria in IMLF(-/-), SkMc cells, and COS cells. PMID:16061942

Tucker, Dawn E; Stewart, Allison; Nallan, Laxman; Bendale, Pravine; Ghomashchi, Farideh; Gelb, Michael H; Leslie, Christina C

2005-10-01

361

Distribution of interferon-gamma mRNA-positive cells in oral lichen planus lesions.  

PubMed

The present study investigated the potential involvement of interferon-gamma (IFN-gamma)-producing cells in the pathogenesis of oral lichen planus (OLP). On biopsies from 10 OLP patients, an in situ hybridization technique was employed to determine the topographical distribution of cells expressing IFN-gamma mRNA. It was estimated that approximately 1% or fewer lesional cells were IFN-gamma mRNA-positive. These cells were mainly encountered lining the basal membrane in a majority of the patients, or were in a few cases circumscribing the infiltrate, but were more seldom localized to the center of the lesion. A slightly higher, but not statistically significant, number of phytohemagglutinin (PHA)-induced IFN-gamma-producing cells, in vitro, was found in blood from 11 other OLP patients compared with blood from matched controls. Equal concentrations of IFN-gamma in supernatants from PHA-stimulated blood cells were detected in the two groups. Similarly, the IFN-gamma response towards C. albicans was alike in OLP and in healthy control (HC) blood cells, indicating normal immunological memory function in the OLP patients. A small set of cells with spontaneous IFN-gamma production was found in OLP and in HC peripheral blood. The data suggest that T-lymphocyte activation and cytokine production act locally and are not reflected in peripheral blood. The localization of the IFN-gamma mRNA-positive cells indicates that the antigenic peptides are presented at the periphery of the mononuclear cell infiltrate. Furthermore, the low frequency of IFN-gamma mRNA-positive cells in the lesions suggests that the disease is maintained by a small number of antigen-specific T cells. PMID:9831961

Simark Mattsson, C; Jontell, M; Bergenholtz, G; Heyden, M; Dahlgren, U I

1998-11-01

362

Complete suppression of reverse annealing of neutron radiation damage during active gamma irradiation in MCZ Si detectors  

NASA Astrophysics Data System (ADS)

For the development of radiation-hard Si detectors for the SiD BeamCal (Si Detector Beam Calorimeter) program for International Linear Collider (ILC), n-type Magnetic Czochralski Si detectors have been irradiated first by fast neutrons to fluences of 1.5×1014 and 3×1014 neq/cm2, and then by gamma up to 500 Mrad. The motivation of this mixed radiation project is to test the radiation hardness of MCZ detectors that may utilize the gamma/electron radiation to compensate the negative effects caused by neutron irradiation, all of which exists in the ILC radiation environment. By using the positive space charge created by gamma radiation in MCZ Si detectors, one can cancel the negative space charge created by neutrons, thus reducing the overall net space charge density and therefore the full depletion voltage of the detector. It has been found that gamma radiation has suppressed the room temperature reverse annealing in neutron-irradiated detectors during the 5.5 month of time needed to reach a radiation dose of 500 Mrad. The room temperature annealing (RTA) was verified in control samples (irradiated to the same neutron fluences, but going through this 5.5 month RTA without gamma radiation). This suppression is in agreement with our previous predictions, since negative space charge generated during the reverse annealing was suppressed by positive space charge induced by gamma radiation. The effect is that regardless of the received neutron fluence the reverse annealing is totally suppressed by the same dose of gamma rays (500 Mrad). It has been found that the full depletion voltage for the two detectors irradiated to two different neutron fluences stays the same before and after gamma radiation. Meanwhile, for the control samples also irradiated to two different neutron fluences, full depletion voltages have gone up during this period. The increase in full depletion voltage in the control samples corresponds to the generation of negative space charge, and this increase in concentration of negative space charge goes up with the neutron fluence. If we assume the reverse annealing is also taking place for the two gamma-irradiated samples with similarly different concentrations of negative space charge generated, the observed effect of no changes in space charge (no changes in Vfd) in these two gamma-irradiated samples would imply that concentrations of positive space charge created in these two control samples are different at the same gamma dose, and gamma irradiation effectively "switched off", the RT (room temperature) reverse annealing of neutron irradiation. It has also been found that as soon as the gamma irradiation stops, the RT reverse annealing of neutron irradiation-induced defects resumes with same rate as that of the control detectors. This behavior in mixed radiation samples (neutron plus gamma) would suggest some nonlinear effect (defects induced by mixed-radiations are not additive of those by individual radiation alone), or interaction of radiation induced acceptor-type and donor-type defects.

Li, Z.; Verbitskaya, E.; Chen, W.; Eremin, V.; Gul, R.; Härkönen, J.; Hoeferkamp, M.; Kierstead, J.; Metcalfe, J.; Seidel, S.

2013-01-01

363

Effect of gamma radiation on growth and survival of common seed-borne fungi in India  

NASA Astrophysics Data System (ADS)

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.

Maity, J. P.; Chakraborty, A.; Chanda, S.; Santra, S. C.

2008-07-01

364

Radiation resistance of a gamma-ray irradiated nonlinear optic chromophore  

NASA Astrophysics Data System (ADS)

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.

Zhang, Cheng; Taylor, Edward W.

2009-11-01

365

Operation of {sup 3}He Proportional Chambers in High Gamma Radiation Fields  

SciTech Connect

Operation of {sup 3}He proportional chambers with irradiated fissile materials is limited because of the sensitivity of these chambers to gamma ray events. The optimum performance of these chambers is achieved with proper selection of an additive gas to the chambers and with proper choice of preamplifier and linear amplifier time constants. The counting efficiency of a 4-atm, {sup 3}He-CO2 chamber is improved from 35% to 43% in a 200 R/hr gamma radiation field by decreasing the linear amplifier time constant. Likewise, the counting efficiency of a 1-atm, {sup 3}He-CF4 is improved from 11% to 14% in a 200 R/hr gamma radiation field by decreasing the linear amplifier time constant. The 4-atm, {sup 3}He-CO2 1-in.-OD chamber has a higher efficiency than the 1-atm, {sup 3}He-CF4 1-in.-OD chamber although the energy resolution of the 3 He-CF4 chamber is better than that for the {sup 3}He-CO2 chamber.

Hill, N.W.; Miller, V.C.; Valentine, T.E.; Williams, J.A.

1999-09-01

366

Random amplified polymorphic DNA analysis of salt-tolerant tobacco mutants generated by gamma radiation.  

PubMed

Salinity is one of the major problems limiting the yield of agricultural products. Radiation mutagenesis is used to improve salt-tolerant mutant plants. In this study, we aimed to improve salt-tolerant mutants of two oriental tobacco varieties. One thousand seeds of each variety (M0) were irradiated with 100, 200, 300, and 400 Gy gamma rays by Cs-137 gamma. In the M1 generation, 2999 single plants were harvested. The next season, these seeds were bulked and planted to obtain M2 progeny. The seeds of 1900 M2 plants were picked separately. Salinity tolerance was tested in the M3 generation. Among M3 plantlets, 10 salt-tolerant tobacco mutants were selected. According to the results of the selection studies, 100- and 200-Gy gamma radiation doses were the effective doses to obtain the desired mutants. Glutathione reductase enzyme activities of salt-tolerant tobacco mutants were determined biochemically as a stress-tolerance marker. The differences between control and salt-tolerant mutants belonging to the Akhisar 97 and ?zmir Özba? tobacco varieties were evaluated by random amplified polymorphic DNA analysis. The total polymorphism rate was 73.91%. PMID:25730072

Çelik, Ö; Atak, Ç

2015-01-01

367

Antioxidative and radioprotective potential of rutin and quercetin in Swiss albino mice exposed to gamma radiation  

PubMed Central

The radioprotective potential of bioflavonoid, rutin (RUT) and quercetin (QRT) was investigated in Swiss albino mice exposed to gamma radiation. The radioprotective potential of RUT and QRT was assessed in pre-treatment group of mice followed on radiation-induced changes in glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (LPO) levels were also analyzed. Elevation in the GSH, GST, SOD, CAT, and decreased LPO levels were observed in RUT and QRT pretreated group when compared to the irradiated animals. Furthermore, it was observed that RUT and QRT treatment was found to inhibit various free radicals generated in vitro, viz., 2,2-diphenyl-1-picrylhydrazyl(DPPH), O2, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS)+, and OH in a concentration-dependent manner. This study clearly demonstrates the free radical scavenging action of RUT and QRT, indicating that it may have its potential as a radioprotective agent. Furthermore, the presence of a phenolic group in RUT and QRT is known to contribute to scavenging the radiation-induced free radicals and inhibition of oxidative stress. Present findings demonstrate the potential of RUT and QRT in mitigating radiation-induced oxidative stress, which may be attributed to the inhibition of radiation-induced decline in the endogenous antioxidant levels and scavenging of radiation-induced free radicals. PMID:23776312

Patil, Shrikant L.; Mallaiah, Somashekarappa Hiriyur; Patil, Rajashekar K.

2013-01-01

368

CCL20, (gamma)(delta) T cells, and IL-22 in corneal epithelial healing  

Technology Transfer Automated Retrieval System (TEKTRAN)

After corneal epithelial abrasion, leukocytes and platelets rapidly enter the corneal stroma, and CCR6 (+) IL-17(+) gamma delta T cells migrate into the epithelium. Gamma delta T-cell-deficient (TCRd(-/-)) mice have significantly reduced inflammation and epithelial wound healing. Epithelial CCL20 mR...

369

Absorption of 10 Gev--1 Tev Gamma Rays by Radiation from Broad-Line Region in 3C 279  

E-print Network

In this paper, we study the photon-photon pair production optical depth for 10 GeV--1 TeV gamma rays from 3C 279 due to the diffuse radiation of broad-line region (BLR). Assuming a power-law spectrum of $E_{\\gamma}^{-a_2}$ for the photon intensity of very high energy (VHE) gamma rays, $a_1 \\gtrsim 405$ and $a_2\\gtrsim 6.4$ are inferred by the integrated photon fluxes measured by MAGIC and HESS. Based on this power-law spectrum, the pre-absorbed spectra are inferred by correcting the photon-photon absorption on the diffuse photons of the BLR (internal absorption) and the extragalactic background light (external absorption). Position of gamma-ray emitting region $R_{\\rm{\\gamma}}$ determines the relative contributions of this two diffuse radiation to the total absorption for 10 GeV--1 TeV gamma rays. The internal absorption could make spectral shape of gamma rays more complex than only corrected for the external absorption, and could lead to the formation of arbitrary softening and hardening gamma-ray spectra. It should be necessary for the internal absorption to be considered in studying 10 GeV--1 TeV gamma rays from powerful blazars. The energies of annihilated gamma-ray photons due to the internal absorption are likely to be mainly reradiated around GeV. Our results indicate that $R_{\\rm{\\gamma}}$ may be between the inner and outer radii of the BLR for 3C 279. This implies for powerful blazars that $R_{\\rm{\\gamma}}$ might be neither inside the BLR cavity nor outside the BLR, but be within the BLR shell. Observations of $\\it GLAST$, MAGIC, HESS, and VERITAS in the near future could give more constraints on the position of the gamma-ray emitting region relative to the BLR.

H. T. Liu; J. M. Bai; L. Ma

2008-07-20

370

Influence of ferulic acid on gamma-radiation induced DNA damage, lipid peroxidation and antioxidant status in primary culture of isolated rat hepatocytes.  

PubMed

Ionizing radiation is known to induce oxidative stress through generation of reactive oxygen species (ROS) resulting in imbalance of the pro-oxidant and antioxidant activities ultimately resulting in cell death. Ferulic acid (FA) is a phytochemical commonly found in fruits and vegetables such as tomatoes, sweet corn, and ricebran. FA exhibit a wide range of pharmacological effects including antiageing, anti-inflammatory, anticancer, antidiabetic, antiapoptotic, and neuroprotective. The present work is aimed at evaluating the radioprotective effect of FA, on gamma-radiation induced toxicity in primary cultures of isolated rat hepatocytes. Hepatocytes were isolated from the liver of rats by collagenase perfusion. The cellular changes were estimated using lipid peroxidative indices like thiobarbituric acid reactive substances (TBARS), the antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH), ceruloplasmin, Vitamins A, E and C and uric acid. DNA damage was analyzed by single cell gel electrophoresis (comet assay). An increase in the severity of DNA damage was observed with increasing dose (1, 2 and 4Gy) of gamma-radiation in cultured hepatocytes. TBARS were increased significantly, whereas the levels of GSH, Vitamins C, E and A, ceruloplasmin, uric acid and antioxidant enzymes were significantly decreased in gamma-irradiated groups. The maximum damage to hepatocytes was observed at 4Gy irradiation. Pretreatment with FA (1, 5 and 10 microg/ml) significantly decrease the levels of TBARS and DNA damage. In addition, pretreatment with FA significantly increased antioxidant enzymes, GSH, Vitamins A, E and C, uric acid and ceruloplasmin levels. The maximum protection of hepatocytes was observed at 10 microg/ml of FA pretreatment. Thus, pretreatment with FA helps in protecting the hepatocytes against gamma-radiation induced cellular damage and can be developed as a effective radioprotector during radiotherapy. PMID:17049709

Srinivasan, M; Sudheer, A Ram; Pillai, K Raveendran; Kumar, P Raghu; Sudhakaran, P R; Menon, V P

2006-12-01

371

Production of interferon-gamma and tumour necrosis factor-alpha by human T-cell clones expressing different forms of the gamma delta receptor.  

PubMed Central

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

Christmas, S E; Meager, A

1990-01-01

372

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)

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.

Redon, Christophe; Dickey, Jennifer; Bonner, William; Sedelnikova, Olga

373

Biological radiation dose from secondary particles in a Milky Way gamma ray burst  

E-print Network

Gamma ray bursts (GBRs) are a class of highly energetic explosions emitting radiation in a very short timescale of a few seconds and with a very narrow opening angle. Although, all GRBs observed so far are extragalactic in origin, there is a high probability of a GRB of galactic origin beaming towards the Earth in the past ~ 0.5 Gyr. Such an intense burst of gamma rays would ionize the atmosphere and deplete the ozone layer. With depleted ozone, there will be an increased flux of solar UVB on the Earth\\~Os surface with harmful biological effects. In addition to the atmospheric damage, secondary particles produced by gamma ray-induced showers will reach the surface. Amongst all secondary particles, muons dominate the ground-level secondary particle flux (99% of the total number of particles) and are potentially of biological significance. Using the Monte Carlo simulation code CORSIKA, we modeled the air showers produced by gamma ray primaries up to 100 GeV. We found that the number of muons produced by hypothe...

Atri, Dimitra; Karam, Andrew

2013-01-01

374

Potentially lethal damage repair in drug arrested G2-phase cells after radiation exposure.  

PubMed

Potentially lethal damage (PLD) repair has been defined as that property conferring the ability of cells to recover from DNA damage depending on the postirradiation environment. Using a novel cyclin dependent kinase 1 inhibitor RO-3306 to arrest cells in the G2 phase of the cell cycle, examined PLD repair in G2 in cultured Chinese hamster ovary (CHO) cells. Several CHO-derived DNA repair mutant cell lines were used in this study to elucidate the mechanism of DNA double-strand break repair and to examine PLD repair during the G2 phase of the cell cycle. While arrested in G2 phase, wild-type CHO cells displayed significant PLD repair and improved cell survival compared with cells released immediately from G2 after irradiation. Both the radiation-induced chromosomal aberrations and the delayed entry into mitosis were also reduced by G2-holding PLD recovery. The PLD repair observed in G2 was observed in nonhomologous end-joining (NHEJ) mutant cell lines but absent in homologous recombination mutant cell lines. From the survival curves, G2-NHEJ mutant cell lines were found to be very sensitive to gamma-ray exposure when compared to G2/homologous recombination mutant cell lines. Our findings suggest that after exposure to ionizing radiation during G2, NHEJ is responsible for the majority of non-PLD repair, and conversely, that the homologous recombination is responsible for PLD repair in G2. PMID:25251700

Maeda, Junko; Bell, Justin J; Genet, Stefan C; Fujii, Yoshihiro; Genet, Matthew D; Brents, Colleen A; Genik, Paula C; Kato, Takamitsu A

2014-10-01

375

Dysregulation of IRP1-Mediated Iron Metabolism Causes Gamma Ray-specific Radioresistance in Leukemia Cells  

PubMed Central

Iron is required for nearly all organisms, playing important roles in oxygen transport and many enzymatic reactions. Excess iron, however, can be cytotoxic. Emerging evidence suggests that radioresistance can be achieved in lower organisms by the protection of proteins, but not DNA, immediately following ionizing radiation (IR) exposure, allowing for improved DNA repair. One potential mechanism for protein protection is controlling and limiting the amount of free iron in cells, as has been demonstrated in the extremophile Deinococcus Radiodurans, reducing the potential for oxidative damage to proteins during exposure to IR. We found that iron regulatory protein 1 (IRP1) expression was markedly reduced in human myeloid leukemia HL60 cells resistant to low linear energy transfer (LET) gamma rays, but not to high LET alpha particles. Stable knockdown of IRP1 by short-hairpin RNA (shRNA) interference in radiosensitive parental cells led to radioresistance to low LET IR, reduced intracellular Fenton chemistry, reduced protein oxidation, and more rapid DNA double-strand break (DSB) repair. The mechanism of radioresistance appeared to be related to attenuated free radical-mediated cell death. Control of intracellular iron by IRPs may be a novel radioresistance mechanism in mammalian cells. PMID:23155415

Haro, Kurtis J.; Sheth, Aneesh; Scheinberg, David A.

2012-01-01

376

Age- and time interval-specific gamma radiation-induced DNA damage in adult maize weevils, Sitophilus zeamais Motschulsky, assessed using comet assays.  

PubMed

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

Hasan, Md Mahbub; Todoriki, Setsuko; Miyanoshita, Akihiro; Imamura, Taro

2012-01-24

377

Radiation track structure is not only important in determining the response of traversed cells but also non-traversed cells.  

NASA Astrophysics Data System (ADS)

The spatial distribution of energy deposition on the scale of DNA, cells and tissue for both low and high-LET radiation is important in determining the subsequent biological response in DNA, cells and ultimately people. In irradiated cells, the biological response has been shown to be critically dependant on the clustering of damage to DNA on the nanometre scale, with high-LET radiation not only producing a higher frequency of complex DNA damage but also typically producing damage sites of greater complexity than those produced by low-LET radiation. The differences in the energy distribution on the micron/cellular scale are also important with regards to chromosome aberration formation. The traversal of a cell by a high-LET track typically produces a non-homogeneous dose distribution through a cell nucleus and correlated DNA double-strand breaks along the path, resulting in an increased probability of complex chromosomal rearrangements (3 or more breaks in 2 or more chromosomes). In addition, in recent years it has become increasing clear that cells do not act in isolation, but the ultimate response of a cell or tissue is dependent on intercellular signalling. This becomes increasingly important at the low doses, or low dose rates, associated with typical human exposures. In order to help characterise the underlying mechanism of intercellular signalling, and how they are perturbed following exposure to ionising radiation, a previously well-defined model system of intercellular induction of apoptosis (IIA) was used, where neighbouring normal cells selectively eliminate transformed cells through cytokine (TGF-beta) and ROS/RNS signalling. The rate of apoptosis in unirradiated transformed cells was found to be enhanced even after extremely low doses of both low-LET (2 mGy gamma-rays) and high-LET (0.3 mGy alpha-particles) with the enhancement independent of dose and radiation quality at medium to high doses. The level of stimulation was found to be also dependent on the fraction of cells irradiated, cell type, levels of TGF-beta, distance between cell populations and oxygen concentration. The study shows that the stimulation of intercellular signalling by radiation required both sufficient energy deposition within irradiated cells and fraction of cells irradiated, with the response dependent on radiation quality only at low doses or when a small fraction of cells are irradiated. These results will be discussed in terms of their potential implications to risks associated with typical human exposures.

Hill, Mark

2012-07-01

378

DNA microarray analyses reveal a post-irradiation differential time-dependent gene expression profile in yeast cells exposed to X-rays and {gamma}-rays  

SciTech Connect

Ionizing radiation (IR) is the most enigmatic of genotoxic stress inducers in our environment that has been around from the eons of time. IR is generally considered harmful, and has been the subject of numerous studies, mostly looking at the DNA damaging effects in cells and the repair mechanisms therein. Moreover, few studies have focused on large-scale identification of cellular responses to IR, and to this end, we describe here an initial study on the transcriptional responses of the unicellular genome model, yeast (Saccharomyces cerevisiae strain S288C), by cDNA microarray. The effect of two different IR, X-rays, and gamma ({gamma})-rays, was investigated by irradiating the yeast cells cultured in YPD medium with 50 Gy doses of X- and {gamma}-rays, followed by resuspension of the cells in YPD for time-course experiments. The samples were collected for microarray analysis at 20, 40, and 80 min after irradiation. Microarray analysis revealed a time-course transcriptional profile of changed gene expressions. Up-regulated genes belonged to the functional categories mainly related to cell cycle and DNA processing, cell rescue defense and virulence, protein and cell fate, and metabolism (X- and {gamma}-rays). Similarly, for X- and {gamma}-rays, the down-regulated genes belonged to mostly transcription and protein synthesis, cell cycle and DNA processing, control of cellular organization, cell fate, and C-compound and carbohydrate metabolism categories, respectively. This study provides for the first time a snapshot of the genome-wide mRNA expression profiles in X- and {gamma}-ray post-irradiated yeast cells and comparatively interprets/discusses the changed gene functional categories as effects of these two radiations vis-a-vis their energy levels.

Kimura, Shinzo [Laboratory of Environmental Biology, Department of Preventive Medicine, Hokkaido University School of Medicine, Sapporo 060-8638 (Japan); Ishidou, Emi [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Kurita, Sakiko [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Suzuki, Yoshiteru [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Shibato, Junko [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Rakwal, Randeep [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)]. E-mail: rakwal-68@aist.go.jp; Iwahashi, Hitoshi [Human Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST) WEST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)

2006-07-21

379

Radiation inactivation of human prostate cancer cells: the role of apoptosis.  

PubMed

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

Algan, O; Stobbe, C C; Helt, A M; Hanks, G E; Chapman, J D

1996-09-01

380

The repair of gamma-radiation-induced DNA damage is inhibited by microcystin-LR, the PP1 and PP2A phosphatase inhibitor.  

PubMed

The genotoxic activity of microcystin-LR (MC-LR) is a matter of debate. MC-LR is known to be a phosphatase inhibitor and it may be expected that it is involved in the regulation of the activity of DNA-dependent protein kinase (DNA-PK), the key enzyme involved in the repair of radiation-induced DNA damage. We studied the effect of MC-LR on the repair capacity of radiation-induced DNA damage in human lymphocytes and human glioblastoma cell lines MO59J and MO59K. A dose of 0.5 microg/ml of MC-LR was chosen because it induced very little early apoptosis which gives no false positive results in the comet assay. Human lymphocytes in G0-phase of the cell cycle were pre-treated with MC-LR for 3 h and irradiated with 2 Gy of gamma radiation. The kinetics of DNA repair was assessed by the comet assay. In addition the frequencies of chromosomal aberrations were analysed. The pre-treatment with MC-LR inhibited the repair of radiation-induced damage and lead to enhanced frequencies of chromosomal aberrations including dicentric chromosomes. The results of a split-dose experiment, where cells were exposed to two 1.5 Gy doses of radiation separated by 3 h with or without MC-LR, confirmed that the toxin increased the frequency of dicentric chromosomes. We also determined the effect of MC-LR and ionizing radiation on the frequency of gamma-H2AX foci. The pre-treatment with MC-LR resulted in reduced numbers of gamma-H2AX foci in irradiated cells. In order to elucidate the impact of MC-LR on DNA-PK we examined the kinetics of DNA repair in human glioblastoma MO59J and MO59K cells. Both cell lines were exposed to 10 Gy of X-rays and DNA repair was analysed by the comet assay. A strong inhibitory effect was observed in the MO59K but not in the MO59J cells. These results indicate that DNA-PK might be involved in DNA repair inhibition by MC-LR. PMID:16434448

Lankoff, A; Bialczyk, J; Dziga, D; Carmichael, W W; Gradzka, I; Lisowska, H; Kuszewski, T; Gozdz, S; Piorun, I; Wojcik, A

2006-01-01

381

Induction of transpositions of MGE Dm412 by {gamma}-radiation in an isogenic line of Drosophila melanogaster  

SciTech Connect

In an isogenic line of Drosophila, transpositions of mobile genetic elements (MGE) Dm412 were induced by {gamma}-radiation at doses of 300, 800, and 1300 R. The rates of induced transpositions were (for each dose, respectively) 3.9 x 10{sup {minus}3}, 1.0 x 10{sup {minus}2}, and 1.87 x 10{sup {minus}2} events per occupied site per haploid genome of the isogenic line per generation. Thus, the transposition rate increased linearly with the radiation dose. The specific rate of {gamma}-radiation-induced transpositions was (1.3 {+-} 0.6) x 10{sup {minus}5} per occupied site per haploid genome of the isogenic line per Roentgen per generation. {gamma}-Radiation-induced hot transposition sites and haplotypes, very similar to those induced by heat shock, were found. It was suggested that the mechanism of induction by {gamma}-radiation involves the heat shock system. Thus, it is more similar to the mechanism of temperature induction than to the direct mutational effect of {gamma}-radiation. Estimates of induced transposition rates per genome for each dose were calculated as 1.1, 3.0, and 5.6 events, respectively, per genome per generation. This level probably corresponds to the subthreshold level of genomes near the {open_quotes}catastrophic border of transpositional losses.{close_quotes} 21 refs., 1 fig., 4 tabs.

Zabanov, S.A. [Institute of Cytology and Genetics, Novosibirsk (Russian Federation); Vasil`eva, L.A.; Ratner, V.A. [Institute of Cytology and Genetics, Novosibirsk (Russian Federation)]|[Novosibirsk State Univ. (Russian Federation)

1995-06-01

382

Radiative-neutron-capture gamma-ray analysis by a linear combination technique  

USGS Publications Warehouse

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.

Tanner, A.B.; Bhargava, R.C.; Senftle, F.E.; Brinkerhoff, J.M.

1972-01-01

383

Gamma-ray CdTe and CdZnTe detectors: investigations and applications in radiation control devices  

NASA Astrophysics Data System (ADS)

In this paper we present results of our investigations on the technology improvement for high-grade CdTe and CdZnTe single-crystals growth as well as results of the obtained materials testing by photoluminescence method. Perspectives for the materials utilization in detectors and devices of radiation control are discussed. Design features and characteristics of the developed personal (gamma) - and X-radiation dosimeters on the base of CdTe detectors and (gamma) -radiation spectrometers on the base of CdZnTe detectors are presented and discussed as well.

Korbutyak, Dmytro V.; Krylyuk, Sergiy G.; Kryuchenko, Yurii V.; Kupchak, Igor; Komar, Vitaliy K.; Nalivaiko, Dmitriy; Smuk, Rostyslav; Storonskii, Yurii

2001-12-01

384

Effect of gamma radiation on chlorobutyl rubber vulcanized by three different crosslinking systems  

NASA Astrophysics Data System (ADS)

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.

Scagliusi, Sandra R.; Cardoso, Elisabeth L. C.; Lugao, Ademar B.

2012-09-01

385

Airborne gamma radiation measurements of soil moisture during FIFE: Activities and results  

NASA Technical Reports Server (NTRS)

Soil moisture measurements were obtained during the summer of 1987 and 1989 near Manhattan, Kansas, using the National Weather Service (NWS) airborne gamma radiation system. A network of 24 flight lines were established over the research area. Airborne surveys were flown daily during two intensive field campaigns. The data collected was sufficient to modify the NWS standard operational method for estimating soil moisture for the Field Experiment (FIFE) flight lines. The average root mean square error of the soil moisture estimates for shorter FIFE flight lines was found to be 2.5 percent, compared with a reported value of 3.9 percent for NWS flight lines. Techniques were developed to compute soil moisture estimates for portions of the flight lines. Results of comparisons of the airborne gamma radiation soil moisture estimates with those obtained using the NASA Pushbroom Microwave Radiation (PBMR) system and hydrological model are presented. The airborne soil moisture measurements, and real averages computed using all remotely sensed and ground data, have been in support of the research of the many FIFE investigators whose overall goal was the upscale integration of models and the application of satellite remote sensing.

Peck, Eugene L.

1992-01-01

386

Gamma radiation process for destruction of toxic polychlorinated biphenyls (Pcbs) in transformer oils.  

PubMed

Polychlorinated biphenyls (PCBs) are synthetic organic chemicals commercially used worldwide in many applications. PCBs were used in oils because of their excellent properties such as good thermal stability, flame resistance, dielectric constant, high break down voltage, high boiling point and low volatility. However, because of their adverse affects on environment and human health, the use of PCBs has been banned now. PCBs are today considered among the widespread pollutants in the global system. PCBs sources still exist in various industrial products and in waste streams such as capacitor oils, lubricating oils, transformer oils, hydraulic oils, paints, rubbers, cables, etc. Several such materials containing PCBs emanating from various sources need to be detoxified before their reuse or before going to landfill for final disposal. Various remedial technologies have been developed in the world to destroy toxic PCBs. The radiolysis has been investigated as an environment-friendly process for waste oil treatment contaminated with PCBs, which may be a better alternative to the globally most widely accepted incineration method. A study was undertaken to detoxify PCBs in transformer oil by gamma radiation using Cobalt 60 source. Analysis of PCBs in transformer oils before and after radiation was carried out by GC-MS instrument. The effect of radiation dose and destruction of PCBs in transformer oils are discussed in details in the present paper. The method used was found to be highly effective and destruction was as high as 79 %. Further, the transformer oil samples were also evaluated before and after radiation to check their quality. The properties of oils were not significantly altered by gamma radiation treatment as evident from the results given in the paper. PMID:17913201

Singh, R K; Nayak, Poonam; Niyogi, U K; Khandal, R K; Singh, Gurdeep

2006-01-01

387

Study of radiation dose induced by cosmic-ray origin low-energy gamma rays and electrons near sea level  

NASA Astrophysics Data System (ADS)

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.

Mrdja, D.; Bikit, I.; Bikit, K.; Slivka, J.; Anicin, I.

2015-02-01

388

Molecular markers of ionizing radiation-induced gene mutations in mammalian cells.  

PubMed

We have isolated independent Chinese hamster ovary (CHO) cell mutants at the hypoxanthine guanine phosphoribosyltransferase (hprt) locus from untreated, 60Co gamma-ray-exposed, and 212Bi alpha-exposed cells and identified the molecular changes underlying the mutation determined by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. Both the parental CHO-K1 cells and the X-ray-sensitive mutant xrs-5 cells were studied. The radiosensitive xrs-5 cells are defective in DNA double-strand break rejoining ability and in V(D)J recombination, which can be complemented by Ku protein. Of the 71 spontaneous CHO-K1 hprt mutants analyzed, 78% showed no change in exon number or size, 20% showed loss of one to eight exons (partial deletion), and 3% showed loss of all nine hprt exons (total deletion). Exposure of CHO-K1 cells to 6 Gy of gamma rays, which reduced survival levels to 10%, produced a high deletion spectrum with 45% of the 20 mutants analyzed showing a loss of one to eight exons and 30% showing total deletion. Exposure to an equitoxic dose of alpha radiation from 212Bi, a 220Rn daughter, resulted in a spectrum similar to the gamma-ray spectrum in that 75% of the 49 mutants analyzed were deletions. To alpha radiation, however, tended to produce larger intragenic deletions than gamma radiation. Of the 92 spontaneous xrs-5 mutants analyzed for deletions, 43% showed a loss of one to eight exons and 14% showed total deletion. This suggests that, in certain regions of the hprt gene, base alterations can be converted into large deletions and alteration in the Ku protein complex can influence this type of mutational process. Exposure to alpha radiation (10% survival) to xrs-5 cells resulted in a deletion spectrum similar to that seen in CHO-K1 cells. Of the 49 mutants analyzed, 43% showed on change in exon number or size, 16% showed a loss of one to eight exons, and 41% showed total deletion. While the defect in xrs-5 cells has a profound effect on spontaneous mutant spectra, this defect does not appear to affect alpha-induced mutation spectra. PMID:8781403

Hsie, A W; Porter, R C; Xu, Z; Yu, Y; Sun, J; Meltz, M L; Schwartz, J L

1996-05-01

389

A Human Espophageal Epithelial Cell Model for Study of Radiation Induced Cancer and DNA Damage Repair  

NASA Technical Reports Server (NTRS)

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, a type of cancer found to have a significant enhancement in incidence in the survivors of the atomic bomb detonations in Japan. Here we present the results of our 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 - 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).

Huff, Janice L.; Patel, Zarana S.; Hada, Megumi; Cucinotta, Francis A.

2008-01-01

390

Gamma radiation damage study of 0.18 µm process CMOS image sensors  

NASA Astrophysics Data System (ADS)

A 0.18 ?m process CMOS image sensor has recently been developed by e2v technologies plc. with a 0.5 megapixel imaging area consisting of 6 × 6 ?m 5T pixels. The sensor is able to provide high performance in a diverse range of applications including machine vision and medical imaging, offering good low-light performance at a video rate of up to 60 fps. The CMOS sensor has desirable characteristics which make it appealing for a number of space applications. Following on from previous tests of the radiation hardness of the image sensors to proton radiation, in which the increase in dark-current and appearance of bright and RTS pixels was quantified, the sensors have now been subjected to a dose of gamma radiation. Knowledge of the performance after irradiation is important to judge suitability for space applications and radiation sensitive medical imaging applications. This knowledge will also enable image correction to mitigate the effects and allow for future CMOS devices to be designed to improve upon the findings in this paper. One device was irradiated to destruction after 120 krad(Si) while biased, and four other devices were irradiated between 5 and 20 krad(Si) while biased. This paper explores the resulting radiation damage effects on the CMOS image sensor such as increased dark current, and a central brightening effect, and discusses the implications for use of the sensor in space applications.

Dryer, Ben; Holland, Andrew; Murray, N. J.; Jerram, Paul; Robbins, Mark; Burt, David

2010-07-01

391

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

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

Neshasteh-Riz, Ali; Rahdani, Rozhin; Mostaar, Ahmad

2014-01-01

392

Interaction of ultraviolet and X-ray radiation with gamma rays produced by a jet in active galactic nuclei  

NASA Technical Reports Server (NTRS)

Recent observations by the Compton Gamma-Ray Observatory give evidence for the existence of a type of blazar with strong gamma-ray emission. Data obtained by EGRET for the quasar 3C 279 show a spectrum between 100 MeV and 10 GeV. Photons of such energies should interact with the X-rays and produce positron/electron pairs. If the optical depth against pair production for the gamma rays is large (tau(gamma gamma) greater than 1), the gamma-ray spectrum should be affected. The importance of this process has been pointed out by, e.g., Maraschi, Ghisellini, & Celotti (1992). Several works (e.g., Dermer 1993; Zbyszewska 1993; Sikora, Begelman, & Rees 1993) concerning gamma-ray radiation from quasar 3C 279 have proposed a model in which the gamma rays are produced via interaction between a moving cloud of relativistic electrons and external soft photons. The presence of gamma rays in active galactic nuclei spectra gives constraints on the localization and the luminosity of the medium which produces ultraviolet/X-ray photons. We investigate what conditions should be fulfilled in the above model to avoid the absorption of the gamma rays due to pair production.

Zbyszewska, Magda

1994-01-01

393

Interaction of ultraviolet and X-ray radiation with gamma rays produced by a jet in active galactic nuclei  

NASA Astrophysics Data System (ADS)

Recent observations by the Compton Gamma-Ray Observatory give evidence for the existence of a type of blazar with strong gamma-ray emission. Data obtained by EGRET for the quasar 3C 279 show a spectrum between 100 MeV and 10 GeV. Photons of such energies should interact with the X-rays and produce positron/electron pairs. If the optical depth against pair production for the gamma rays is large (tau(gamma gamma) greater than 1), the gamma-ray spectrum should be affected. The importance of this process has been pointed out by, e.g., Maraschi, Ghisellini, & Celotti (1992). Several works (e.g., Dermer 1993; Zbyszewska 1993; Sikora, Begelman, & Rees 1993) concerning gamma-ray radiation from quasar 3C 279 have proposed a model in which the gamma rays are produced via interaction between a moving cloud of relativistic electrons and external soft photons. The presence of gamma rays in active galactic nuclei spectra gives constraints on the localization and the luminosity of the medium which produces ultraviolet/X-ray photons. We investigate what conditions should be fulfilled in the above model to avoid the absorption of the gamma rays due to pair production.

Zbyszewska, Magda

1994-06-01

394

Effective Atomic Numbers of Lanthanides with Gamma Radiation for Photon Energy Absorption  

NASA Astrophysics Data System (ADS)

Effective atomic numbers for photon energy absorption, ZPEA,eff have been calculated for photon from 1 keV to 20 MeV for selected oxides of lanthanides, such as Lanthanum oxide, Cerium oxide, Samarium oxide, Europium oxide, Dysprosium oxide, Thulium oxide, Ytterbium oxide. The ZPEA,eff values then compared with ZPI,eff for photon interaction. The ZPEA,eff values have been found to change with energy and composition of selected lanthanides. Oxides of lanthanides are considered as better shielding materials to the exposure of gamma radiation. The values of effective atomic number for photon energy absorption help in the calculation of absorbed dose.

Shantappa, Anil; Hanagodimath, S. M.

395

Use of gamma ray radiation to parallel the plates of a Fabry-Perot interferometer  

NASA Technical Reports Server (NTRS)

The use of gamma radiation to parallel the plates of a Fabry-Perot etalon is examined. The method for determining the etalon parallelism, and the procedure for irradiating the posts are described. Changes in effective gap for the etalon over the surface are utilized to measure the parallelism of the Fabry-Perot etalon. An example in which this technique is applied to an etalon of fused silica plates, which are 132 mm in diameter and coded with zinc sulfide and cryolite, with Zerodur spaces 2 cm in length. The effect of the irradiation of the posts on the thermal performance of the etalon is investigated.

Skinner, Wilbert R.; Hays, Paul B.; Anderson, Sally M.

1987-01-01

396

Estimation of external gamma radiation dose in the area of Bory Stobrawskie forests (PL).  

PubMed

The study assessed the radiological risks associated with the presence of natural and artificial radionuclides in the Bory Stobrawskie forests (PL). Using the conversion factors given by UNSCEAR and the measurements results of (232)Th series, (238)U series, (40)K, and (137)Cs specific activities in the 10-cm soil layer the values of absorbed dose (D) and the annual effective dose equivalent derived from terrestrial gamma radiation (E) were calculated. The calculated dose was compared with doses directly measured on the area studied. PMID:21972034

Do?ha?czuk-?ródka, Agnieszka

2012-09-01

397

Gamma spectroscopic measurements using the PID350 pixelated CdTe radiation detector  

E-print Network

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.

K. Karafasoulis; K. Zachariadou; S. Seferlis; I. Papadakis; D. Loukas; C. Lambropoulos; C. Potiriadis

2010-11-15

398

gamma-Glutamyl transpeptidase expression in Ewing's sarcoma cells: up-regulation by interferons.  

PubMed Central

The genetic hallmark of Ewing's sarcoma family of tumours (ET) is the presence of the translocation t(11;22)(q24;q12), which creates the ET fusion gene, leading to cellular transformation. Five human gamma-glutamyl transpeptidase (gamma-GT) genes are located near the chromosomal translocation in ET. gamma-GT is a major enzyme involved in glutathione homoeostasis. Five human cell lines representative of primary or metastatic tumours were investigated to study whether gamma-GT alterations could occur at the chromosomal breaks and rearrangements in ET. As shown by enzymic assays and FACS analyses, all ET cell lines consistently expressed a functional gamma-GT which however did not discriminate steps of ET progression. As shown previously [Sancéau, Hiscott, Delattre and Wietzerbin (2000) Oncogene 19, 3372-3383], ET cells respond to the antiproliferative effects of interferons (IFNs) type I (alpha and beta) and to a much less degree to IFN type II (gamma). IFN-alpha and -beta arrested cells in the S-phase of the cell cycle. We found an enhancement of gamma-GT mRNA species with IFN-alpha and -beta by reverse transcriptase-PCR analyses. This is reflected by up-regulation of gamma-GT protein, which coincides with the increase in gamma-GT-specific enzymic activity. Similarly, IFNs up-regulate the levels of gamma-GT in another IFN-responsive B cell line. Whether this up-regulation of gamma-GT by IFNs is of physiological relevance to cell behaviour remains to be studied. PMID:12049636

Bouman, Lena; Sancéau, Josiane; Rouillard, Dany; Bauvois, Brigitte

2002-01-01

399

Effect of Meteorological Phenomena in Measures of Background Radiation X and Gamma Rays in São José dos Campos, SP, Brazil  

NASA Astrophysics Data System (ADS)

The objective of this work was to perform a study on the influence of meteorological phenomena on the background radiation X and gamma rays in São José dos Campos, SP, Brazil on the last three years. For this, we performed the monitoring of the integrated radiations and also of the main meteorological parameters (rainfall, relative humidity, temperature and pressure) daily without interruptions and time resolution of one minute. Measurements of X and gamma radiation in the range of energies from 30 keV to 10 MeV, were carried out using a scintillator crystal of sodium iodide activated with Tallium [NaI(Tl)] coupled to a photomultiplier, with energy resolution of 15%. Rainfall, atmospheric pressure, temperature, and relative humidity were recorded using sensors coupled to a five-channel specific data logger. By correlating the data from the measurements of intensity of X and gamma radiations with the meteorological parameters, it was found that atmospheric precipitation with or without electric discharges phenomenon that was affected more in the spectrum of background radiation profile. Some of the reasons why these changes occur in the background profile are due the presence of environmental radon gas that is drawn to the surface during the occurrences of local rainfall. During dry periods, the spectra of X and gamma radiations showed a daily cycle (24 hour). In relation to relative humidity, temperature and pressure, it was found that these parameters had negligible influence on the profile changes of the background radiation in São José dos Campos, SP, Brazil.

Gomes, Marcelo; Spjeldvik, Walther; Gusev, Anatoly; Alves, Mauro; Martin, Inacio; Pinto, Marcos; Ferro, Marco A.; Concei, Flavio

400

Spectral analysis of paramagnetic centers induced in human tooth enamel by x-rays and gamma radiation  

NASA Astrophysics Data System (ADS)

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.

Kirillov, V. A.; Kuchuro, I. I.

2010-03-01

401

Spirosoma radiotolerans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil.  

PubMed

A Gram-negative, short-rod-shaped bacterial strain with gliding motility, designated as DG5A(T), was isolated from a rice field soil in South Korea. Phylogenic analysis using 16S rRNA gene sequence of the new isolate showed that strain DG5A(T) belong to the genus Spirosoma in the family Spirosomaceae, and the highest sequence similarities were 95.5 % with Spirosoma linguale DSM 74(T), 93.4 % with Spirosoma rigui WPCB118(T), 92.8 % with Spirosoma luteum SPM-10(T), 92.7 % with Spirosoma spitsbergense SPM-9(T), and 91.9 % with Spirosoma panaciterrae Gsoil 1519(T). Strain DG5A(T) revealed resistance to gamma and UV radiation. Chemotaxonomic data showed that the most abundant fatty acids were summed feature C(16:1) ?7c/C(16:1) ?6c (36.90 %), C(16:1) ?5c (29.55 %), and iso-C(15:0) (14.78 %), and the major polar lipid was phosphatidylethanolamine (PE). The DNA G+C content of strain DG5A(T) was 49.1 mol%. Together, the phenotypic, phylogenetic, and chemotaxonomic data supported that strain DG5A(T) presents a novel species of the genus Spirosoma, for which the name Spirosoma radiotolerans sp. nov., is proposed. The type strain is DG5A(T) (=KCTC 32455(T) = JCM19447(T)). PMID:24748440

Lee, Jae-Jin; Srinivasan, Sathiyaraj; Lim, Sangyong; Joe, Minho; Im, Seonghun; Bae, So Il; Park, Kyoung Ryun; Han, Ji-Hee; Park, Se-Hee; Joo, Bo-Min; Park, Sol-Ji; Kim, Myung Kyum

2014-09-01

402

A meta-analysis of leukaemia risk from protracted exposure to low-dose gamma radiation  

PubMed Central

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

Schubauer-Berigan, M K

2010-01-01

403

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

SciTech Connect

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.

Zach, R.; Mayoh, K.R.

1982-12-01

404

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

SciTech Connect

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.

Zach, R.; Mayoh, K.R.

1982-12-01

405

Development of human epithelial cell systems for radiation risk assessment  

NASA Technical Reports Server (NTRS)

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 essent