Some aspects of radiation-induced free-radical chemistry of biologically important molecules

International Nuclear Information System (INIS)

Sonntag, C. von

1992-01-01

Biologically relevant material is usually associated with considerable amounts of water. When ionizing radiation interacts with such material one must consider two modes of energy deposition: the direct effect (ionizing radiation is absorbed by the biomolecules) and the indirect effect (ionizing radiation is absorbed by the surrounding water). In the direct effect, radical cations plus electrons, and excited states of the biomolecules are formed. In the indirect effect the water is decomposed resulting in the formation of the water radicals OH,H and e aq - . These reactive intermediates then interact with the biomolecules. When such systems are irradiated oxygen is often present. As a result of this, the radicals formed in the biomolecules by the various routes are converted into the corresponding peroxyl radicals. In certain cases, e.g. with the nucleobases of DNA, radical cations can be produced in dilute aqueous solutions by radiation-generated SO 4 - radicals, and the fate of these nucleobase radical cations studied by pulse radiolysis and product analysis. Attention will be drawn to the fact that frequently some of the reaction products of the radical cations with water are identical to those formed by OH radical attack, but that there are also marked differences. Similarly, protonation of radical anions (formed by the reaction of solvated electrons with the biomolecules) and the reaction of H-atoms with these molecules can lead to radical intermediates with considerably differing characteristics. Our present knowledge of the variety of reactions of the peroxyl radicals occurring in aqueous solutions will be briefly discussed, emphasizing the large variety of HO 2 /O 2 - elimination reactions and pointing to the reversibility of the oxygen addition (RO 2 →R + O 2 ) in some systems recently studied. (author)

Water structure versus radical scavenger theories as explanations for the suppressive effects of DMSO and related compounds on radiation-induced transformation in vitro

Energy Technology Data Exchange (ETDEWEB)

Kennedy, A.R.; Symons, M.C.

1987-05-01

We report here that dimethylsulfoxide (DMSO): suppresses radiation-induced transformation in vitro, even when DMSO treatments begin as late as 10 days post-irradiation (when cells are in the confluent, stationary phase of growth); inhibits the 12-O-tetradecanoylphorbol-13-acetate (TPA) enhancement of radiation-induced transformation in vitro; does not affect the expression of transformed cells as foci (when surrounded by non-transformed cells); and may be affecting radiation-induced transformation through its solvent properties (i.e. the Water Structure theory), while its effects on the TPA enhancement of radiation transformation may be mediated by its free radical scavenging abilities. DMSO, dimethylformamide (DMF) and dimethylacetamide (DMA) are similar solvents which are all very effective in their ability to suppress radiation-induced transformation in vitro (at concentrations in the cellular media down to 0.01%). As DMSO is known to be an extremely effective OH. free-radical scavenging agent, while DMF and DMA are not as efficient at scavenging free radicals, our results suggest that properties other than free-radical scavenging ability may be important in the suppressive effects of these compounds on radiation-induced transformation in vitro. It is known that low concentrations of such basic aprotic solvents modify water structure so as to suppress the protic (H-bond donor) reactivity of water and enhance its basic (H-bond receptor) reactivity. These reactivity changes may well be responsible for the effects noted above. DMSO, DMF and DMA are also capable of suppressing the TPA enhancement of radiation transformation (at concentrations of the compounds of 0.1% or higher). For this effect, the ability of these compounds to scavenge OH. shows a general correlation with their ability to suppress the TPA enhancement of transformation, suggesting that the Radical Scavenger theory may explain the ability of DMSO to suppress promotion in vitro.

Melatonin against radiation induced free radicals: a study on tissues of Swiss albino mice

International Nuclear Information System (INIS)

Bhatia, A.L.; Manda, K.

2003-01-01

Full text: Antioxidant enzymes are part of the primary cellular defense against free radicals generated by radiation. Reports on low level chronic administration of melatonin with its antiradiation influence are scanty. Although compelling logic suggests that melatonin may be effective for a variety of disorders, the mode and optimal dose of melatonin is still not clear. Most studies have used doses of supraphysiological blood levels. Present investigation reports that melatonin in relatively lower concentrations increases the mRNA of both superoxide dismutases (SODs) and glutathione peroxidase (GSH-Px) and mediates possibly through receptors. The influence of low dose chronic administration (0.10 mg/Kg body weight/day for 15 days) of melatonin was studied against radiation-induced oxidative stress in 6 to 8 weeks old mice. Just after 24 hours of the last dose in various tissues viz. brain, liver, spleen and kidney were studied for lipid peroxidation, reduced glutathione (GSH), glutathione disulphide (GSSG), glutathione peroxidase (GSH-Px), protein, RNA, DNA and serum phosphatase activity. Radiation induced augmentation in the level of lipid peroxidation, glutathione disulphide (GSSG) and acid phosphatase was significantly ameliorated by pre-irradiation treatment with melatonin. Radiation induced depletion in the level of reduced glutathione (GSH), glutathione peroxidase (GSH-Px) and alkaline phosphatase is significantly averted by melatonin administration. Regression analysis of survival data yielded LD50/30 as 7.16 Gy and 11Gy for control (irradiation alone) and experimental (melatonin + irradiation), respectively. Animals produced a dose reduction factor (DRF) as 1.53. Radiation induced deficit in the body and organ weight was also significantly thwarted in the melatonin pre-treated mice. Results indicate the antioxidative properties of melatonin against the gamma radiation. The findings support the results showing melatonin as a free radical scavenger, and

Modification by cystamine of radiation-induced free radical damages to biomolecules in tissues of mouse organs

International Nuclear Information System (INIS)

Svistunenko, D.A.; Gudtsova, K.V.

1989-01-01

The method of low-temperature ESR-spectroscopy was used to study a modifying effect of cystamine on the yield of radiation-induced free radicals in different biomolecules of liver and spleen tissues of mice. Intraperitoneal administration of cystamine (150 mg/kg) 15 min before isolation and freezing of the tissues was shown to reduce by 11 per cent the yield of radicals of H-adducts of thymine DNA bases, to decrease by 23 per cent the yield of radicals of triacyglycerol and phospholipid radiolysis, and to increase by 24 per cent the yield of radicals of lipid fatty acid residues in splenic tissues. According to the criterion used, cystamine has no modyfying action on the yield of free-radical damages to liver biomolecules

A method for detection of hydroxyl radicals in the vicinity of biomolecules using radiation-induced fluorescence of coumarin

International Nuclear Information System (INIS)

Makrigiorgos, G.M.; Baranowska-Kortylewicz, J.; Bump, E.; Sahu, S.K.; Berman, R.M.; Kassis, A.I.

1993-01-01

A novel method is described to quantitate radiation-induced hydroxyl radicals in the vicinity of biomolecules in aqueous solutions. Coumarin-3-carboxylic acid (CCA) is a non-fluorescent molecule that, upon interaction with radiation in aqueous solution, produces fluorescent products. CCA was derivatized to its succinimidyl ester (SECCA) and coupled to free primary amines of albumin, avidin, histone-H1, polylysine, and an oligonucleotide. When SECCA-biomolecule conjugates were irradiated, the relationship between induced fluorescence and dose was linear in the dose range examined (0.01-10 Gy). The data indicate that the induction of fluorescence on SECCA-biomolecule conjugates records specifically the presence of the hydroxyl radical in the immediate vicinity of the irradiated biomolecule. The method is rapid and sensitive, uses standard instrumentation, and the sample remains available for further studies. (Author)

Relationship between human tooth enamel free radical concentration and radiation dose

International Nuclear Information System (INIS)

Zhou Yongzeng; Wang Jiadong; Jia Xiaomei; Wu Ke; Cong Jianbo; Sun Cunpu

1999-01-01

Free radical concentrations of 25 adult tooth enamel samples were measured by electron spin resonance (ESR) technique in this paper, and the relationship between free radical concentration of tooth enamel and radiation dose was also investigated. In the 25 adult enamel samples they are 16 male samples and 9 female samples, Ages of tooth donors range from 18-41 years. Difference in background ESR signal intensity between male and female samples was no observed; free radical concentration (or increment of radiation-induced free radical concentration) in tooth enamel increases linearly with increasing of radiation dose. In the case of radiation accident, the study results of this paper could be applied to dose estimation when conditions of ESR measurement of exposed individual tooth enamel are similar to measurement conditions of dose-effect calibration curve in this paper

Graphdiyne Nanoparticles with High Free Radical Scavenging Activity for Radiation Protection.

Science.gov (United States)

Xie, Jiani; Wang, Ning; Dong, Xinghua; Wang, Chengyan; Du, Zhen; Mei, Linqiang; Yong, Yuan; Huang, Changshui; Li, Yuliang; Gu, Zhanjun; Zhao, Yuliang

2018-03-06

Numerous carbon networks materials comprised of benzene moieties, such as graphene and fullerene, have held great fascination for radioprotection because of their acknowledged good biocompatibility and strong free radical scavenging activity derived from their delocalized π-conjugated structure. Recently, graphdiyne, a new emerging carbon network material consisting of a unique chemical structure of benzene and acetylenic moieties, has gradually attracted attention in many research fields. Encouraged by its unique structure with strong conjugated π-system and highly reactive diacetylenic linkages, graphdiyne might have free radical activity and can thus be used as a radioprotector, which has not been investigated so far. Herein, for the first time, we synthesized bovine serum albumin (BSA)-modified graphdiyne nanoparticles (graphdiyne-BSA NPs) to evaluate their free radical scavenging ability and investigate their application for radioprotection both in cell and animal models. In vitro studies indicated that the graphdiyne-BSA NPs could effectively eliminate the free-radicals, decrease radiation-induced DNA damage in cells, and improve the viability of cells under ionizing radiation. In vivo experiments showed that the graphdiyne-BSA NPs could protect the bone marrow DNA of mice from radiation-induced damage and make the superoxide dismutase (SOD) and malondialdehyde (MDA) (two kinds of vital indicators of radiation-induced injury) recover back to normal levels. Furthermore, the good biocompatibility and negligible systemically toxicity responses of the graphdiyne-BSA NPs to mice were verified. All these results manifest the good biosafety and radioprotection activity of graphdiyne-BSA NPs to normal tissues. Therefore, our studies not only provide a new radiation protection platform based on graphdiyne for protecting normal tissues from radiation-caused injury but also provide a promising direction for the application of graphdiyne in the biomedicine field.

Radiation-induced electron paramagnetic resonance signal and soybean isoflavones content

International Nuclear Information System (INIS)

Oliveira, Marcos R.R. de; Mandarino, José M.G.; Mastro, Nelida L. del

2012-01-01

Electron Paramagnetic Resonance (EPR) is a well-known spectroscopic technique that detects paramagnetic centers and can detect free radicals with high sensitivity. In food, free radicals can be generated by several commonly used industrial processes, such as radiosterilization or heat treatment. EPR spectroscopy is used to detect radioinduced free radicals in food. In this work the relation between EPR signal induced by gamma irradiation treatment and soybean isoflavones content was investigated. Present results did not show correlation between total isoflavones content and the EPR signal. Nevertheless, some isoflavone contents had a negative correlation with the radiation-induced EPR signal. - Highlights: ► Electron Paramagnetic Resonance (EPR) detects free radicals. ► Ionizing radiation as free radicals inducer. ► Total soybean isoflvones do not correlate with radiation-induced EPR intensity but a soybean glucosyl glucoside isoflavone does.

Synchrotron radiation structure analyses of the light-induced radical pair of a hexaarylbiimidazolyl derivative. Origin of the spin-multiplicity change

CERN Document Server

Kawano, M; Matsubara, K; Imabayashi, H; Mitsumi, M; Toriumi, K; Ohashi, Y

2002-01-01

In situ synchrotron radiation structure analyses of a light-induced radical pair from o-Cl-HABI were performed by using an X-ray vacuum camera at 23-70K at the BL02B1 station of SPring-8. The combined results of X-ray analysis with theoretical calculation, IR, and UV-vis spectroscopy reveal that a slight conformational change of the radical pair causes the drastic spin-multiplicity change during 2-140K. (author)

Gamma-sterilization-induced radicals in biodegradable drug delivery systems

International Nuclear Information System (INIS)

Maeder, K.; Swartz, H.M.; Domb, A.

1996-01-01

Electron paramagnetic resonance (EPR) spectroscopy (1.2 and 9.25 GHz, 25 o C) was used to characterize free radicals in gamma-ray sterilized biodegradable polymers of the type which are in clinical use. Free radicals were detected in all irradiated polymer samples. The temperature of irradiation (25 o vs dry ice temperature) had only a minor influence on the yield of radicals and the shape of the EPR spectra. In contrast, the composition of the polymers and the drugs incorporated in them did strongly influence the amount of radiation-induced free radicals and their reactivity. In general, polymers with high melting points and crystallinity had the highest yields of radicals observable at room temperature. We were able to use the free radicals induced by the usual sterilization procedures to follow the penetration of water and the degradation of the polymers in vitro and in vivo. The ability of in vivo EPR to follow drug delivery noninvasively and continuously in vivo, using the free radicals induced in the usual sterilization process indicates that this approach could be applied immediately for the characterization of these drug delivery systems in experimental animals and in the near future should be able to be used in human subjects. (author)

Analysis of decay of radicals induced in irradiated foods during long storage

International Nuclear Information System (INIS)

Kishita, Keigo; Kawamura, Shoei; Nakamura, Hideo; Ukai, Mitsuko; Kikuchi, Masahiro; Kobayashi, Yasuhiko

2013-01-01

By electron spin resonance (ESR) spectroscopy, we revealed free radicals in γ-ray irradiated foods ; black pepper, green coffee bean, cereal flour and ginseng. We also analyzed the decay behavior of radiation induced free radicals during long storage. The ESR spectrum of experimental irradiated foods consists of a sextet signal centered at g=2.0 and a singlet signal at the same g-value position and a singlet signal at g=4.0. The ESR spectrum of the cereal flour sample showed only singlet signal at g=2.0. The singlet signal at g=2.0 is originated from organic free radicals and its peak intensity showed the dependence of γ-ray radiation dose levels. But the signal intensity was decreased during storage. Only after 3 hours of radiation treatment the peak intensity was decreased fast and after that the intensity was decreased slowly. The analysis of radical decay process using the simulation methods based on the theory of reaction speed, the three decay behavior was showed. It is considered that at least three or more kinds of radicals were induced in irradiated foods and in decay during long time storage. (author)

Radiation-induced polymerization and radiation effect on polymers

International Nuclear Information System (INIS)

Seguchi, Tadao

1977-12-01

The processes of radiation-induced polymerization of monomers and also radiation effects on polymers have been studied by instrumental analyses of electron spin resonance (ESR), nuclear magnetic resonance (NMR) and electron microscopy. In radiation-induced polymerization, graft-copolymerization and absorbed state polymerization were taken up. For graft-copolymerization, monomers such as methylmethacrylate and butadiene were made to react with irradiated polyethylene, and behaviors of the initiating radicals and propagating radicals were followed under the reaction by ESR. For absorbed state polymerization, acrylonitrile/zeolite and methylmethacrylate/zeolite were chosen. Absorbed monomers were irradiated at 77 0 K and polymerized at room temperature. Active species and the concentrations were measured by ESR and the yields of polymer were observed by NMR. In radiation effect on polymers, polyvinylfluoride, polyvinylidenfluoride and polytetrafluoroethylene were taken up. Active species trapped in the polymer matrixes were identified and decay and reactivity of the species were also studied. On the basis of information from the electron microscopy and x-ray analysis, radiation effects on these polymers are described. In polytetrafluoroethylene produced by radiation polymerization, the relation between morphology and polymerization conditions and also the process of crystallization during polymerization were studied. (auth.)

Radicals of DNA and DNA nucleotides generated by ionising radiation

International Nuclear Information System (INIS)

Przybytniak, G.

2004-01-01

A first stage of cell processes leading to DNA damage of initiated by radical reactions. In a model system such transformations were generated by ionising radiation which involves production of electron loss and electron gain centers of the substrate and radical formation. Using cryogenic ESR spectroscopy it was found that the DNA nucleotides, which convert to radical anions upon electron capture undergo the separation of unpaired spin and charge due to protonation. Circular and linear dichroism studies enabled to conclude that iron ions(III) induce strong changes in the DNA helical structure indicating their coordination with nitrogen bases. The repair of DNA radicals produced via radiolytic oxidation, i.e. the guanine radical cation and the allyl type radical of thymine, is possible at elevated temperatures due to the involvement of sulphydryl groups. The influence of the thiol charge is then limited

Studies on protective effects of superoxide dismutase on radiation induced-chromosomal aberrations

International Nuclear Information System (INIS)

Zheng Siying; Jiang Jiagui; Lin Xingcheng

1987-09-01

This study demonstrates that radiation induced-chromosomal aberrations are not only due to the direct effect of radiation h it , but the indirect effect of free radical as well. Therefore, chromosome damage induced by radiation may be reduced by adding exogenous SOD into the radiation exposed lymphocyte culture to eliminate the superoxide free radical which damages DNA. On the other hand, however, the radiosensitivity of lymphocytes can be raised by adding SOD inhibitor (DDC) into the lymphocyte culture, which makes radiation induced-chromosomal damages more severely

DNA damage induced by radiation plasmodial mixed + gamma thermal neutrons in the presence and absence of free radical scavenger

International Nuclear Information System (INIS)

Rodriguez Gual, Maritza; Mas Milian, Felix; Gouveia, Andreia; Deppman, Airton

2010-01-01

In this work is quantified the damage in DNA plasmid induced by mixed radiation (thermal neutron and gamma rays) for first time. For the study was used the pBs KS+ plasmid of 2961 bp in aqueous solution of the 88 ng/μL with 0, 2 and 20 mmol/L of glycerol which acts as a free radicals scavenger. This plasmid changes its form of supercoiled to circular when a simple strand break is produced, and passes to a linear form when a double strand break is produced in the chain. Quantifying the fractions that exist in each of these forms is possible to estimate the effect of radiation on DNA. The irradiations were carried out in the radial channel 3 at IEA-R1 research reactor of the Instituto de Pesquisas Energeticas y Nucleares in Sao Paulo, Brazil. DNA forms were separated by agarose gel electrophoresis. For quantification the program GelAnalis was used. The values of the fractions of DNA in various forms were plotted as a function of dose and fitted to exponential and linear functions to obtaining the probabilities of simple and double strand breaks normalized by dose and molecular mass. The results showed the protective action of free radical scavenger against damage induced for radiation which corroborates the previous results found with other ionizing radiations. Yields of SSB and DSB will be of interest for the validation of the different models that attempt to reproduce the experimental results

Mechanism of radiation-induced degradation of poly(methyl methacrylate)

International Nuclear Information System (INIS)

Ichikawa, Tsuneki; Oyama, Ken-ichi; Yoshida, Hiroshi

1995-01-01

ESR and gel permeation chromatographic measurements of poly(methyl methacrylate) γ-irradiated between 77 K and 300 K have been carried out to elucidate the mechanism of radiation-induced degradation of the polymer. It is revealed that the scission of the main chain is not taken place immediately after the absorption of radiation energy but is induced by the intramolecular radical conversion of the side-chain -COOCH 2 radical to the tertiary -CH 2 -C(CH 3 )- radical followed by the main-chain β-scission of the latter radical. The degradation is not taken place below 190 K, because the side-chain radical starts to convert only above 190 K. The residual monomer in the polymer reacts with the side-chain radical below 190 K to generate the stable propagating-type radical, so that the degradation is suppressed even after warming the polymer to the ambient temperature. (author)

Changes induced in spice paprika powder by treatment with ionizing radiation and saturated steam[Food conservation; Spice paprika; Rheology; Colorimetry; Free radicals

Energy Technology Data Exchange (ETDEWEB)

Kispeter, J. E-mail: kispeter@szef.u-szeged.hu; Bajusz-Kabok, K.; Fekete, M.; Szabo, G.; Fodor, E.; Pali, T. E-mail: tpali@nucleus.szbk.u-szeged.hu

2003-12-01

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

Radiation induced degradation of DNA in photodynamic therapy of cancer

International Nuclear Information System (INIS)

Ion, Rodica; Scarlat, F.; Niculescu, V.I.R.; Scarlat, Fl.; Gunaydin, Keriman

2001-01-01

DNA is a critical cellular target for oxidative processes induced by physical and chemical stresses. It is known that the direct effect of ionizing radiation on DNA results mainly in base ionization and may lead to mutation, carcinogenesis and cell death. The degradation of DNA induced by laser and ionizing radiation (electron and photon beam) is analyzed in this paper. The ionizing radiation degradation of DNA is a radical process. A series of lesions among the major base degradation product has been measured in isolated DNA exposed to gamma radiation in aerated aqueous solution. Degradation can be accounted for by the formation of hydroxyl radicals upon radiolysis of water (indirect effect). The production of DNA damage by ionizing radiation involves two mechanisms, direct and indirect effects. Direct effect leads to ionization and excitation of DNA molecules, while indirect effect is due to the interaction of reactive species, in particular of OH radicals produced by water radiolysis, with targets in DNA. The relative contribution of the two mechanisms in damaging DNA depends on the type of radiation. Single strand breaks and base damage seem to be mainly produced by the attack of hydroxyl radicals on DNA, whereas double strand breaks result predominantly of direct energy deposition. The four bases are degraded in high yield. Direct effect has been mimicked by photo-induced electron abstraction from the bases producing their radical cation. The base damage may also occur from the formation of radical cation of purine and pyrimidine components. When DNA is irradiated in solution, single strand breaks are mainly due to the abstraction of an H atom from the 4 ' position of 2 ' -deoxyribose by the attack of OH radicals produced by water radiolysis. Quantification of the modified bases showed the guanine is the preferential target. Ionizing radiation induces several types of DNA modifications, including chain breaks, DNA-protein cross-links, oxidized DNA bases

Radiation-induced linking reactions in polyethylene

International Nuclear Information System (INIS)

Zoepfl, F.J.

1983-01-01

Three types of measurements are reported relating to chemical reactions in polyethylene induced by ionizing radiation: 1) viscometric and low-angle laser light scattering measurements to determine the effect of a radical scavenger on the yield of links; 2) calorimetric measurements to determine the effect of radiation-induced linking on the melting behavior of polyethylene; and 3) high-resolution solution carbon 13 nuclear magnetic resonance (NMR) spectrometry measurements to determine the nature of the links and the method of their formation. The NMR results present the first direct detection of radiation-induced long-chain branching (Y links) in polyethylene, and place an apparent upper limit on the yield of H-shaped crosslinks that are formed when polyethylene is irradiated to low absorbed doses. The effect of radiation-induced linking on the melting behavior of polyethylene was examined using differential scanning calorimetry (DSC). It was found that radiation-induced links do not change the heat of fusion of polythylene crystals, but decrease the melt entropy and increase the fold surface free energy per unit area of the crystals. The carbon 13 NMR results demonstrate that long-chain branches (Y links) are formed much more frequently than H-shaped crosslinks at low absorbed doses. The Y links are produced by reactions of alkyl free radicals with terminal vinyl groups in polyethylene

X-band ESR study on evaluation of radicals induced in pasteurized pepper

International Nuclear Information System (INIS)

Matsuura, Masaaki; Ogawa, Satoko; Ukai, Mitsuko; Oowada, Shigeru

2007-01-01

The radical properties of pasteurized pepper were investigated by means of X-band ESR spectroscopy. Pasteurization process was done by irradiation or steam. There were three radicals in the specimens before and after pasteurization. Upon irradiation a new radical was found. ESR peak intensity of specimen before and after parturition with steam was almost same level. Peak intensity of radiated pepper showed almost 4 times as compare with that of non treated pepper. Radical activity of the specimens after pasteurization showed almost same value. We concluded that radicals were induced by irradiation. But the radical activity was not changed before and after pasteurization. (author)

Protection from radiation-induced enteropathy by elemental diet feeding: The role of free radicals

International Nuclear Information System (INIS)

McArdle, A.H.; Duong, M.N.

1991-01-01

Free radicals have been implicated in intestinal reperfusion injury following ischemia and in epithelial cell damage resulting from ionizing radiation. Elemental diets (ED) have been shown to afford significant prophylaxis to the intestine from these injuries. The purpose of the present study was to investigate whether ED alters the activity of the defense mechanisms necessary for free radical removal. Six female dogs, fed on normal dog chow, had a 30 cm resection of terminal ileum to form Thiry-Vella loops. The main intestine was biopsied and anastomosed. Two weeks later, biopsies were taken from the lips of the loops. Following this, the loops were fed daily with ED another 2 weeks and biopsied again. The dogs were then placed on ED for 3 days before and during 4 days of pelvic irradiation, and the loops also were fed ED daily; after which the animals were again anesthetized, and the loops and main intestine were biopsied. All biopsies were processed for histology, and assayed for xanthine oxidase (XO), superoxide dismutase (SOD), glutathione peroxidase (GSP) and catalase (CAT). The XO and SOD pathway of free oxygen radical generation and scavenging are not affected by radiation. However, ED lowers both XO and SOD activity and may result in a reduced production of peroxides. The significantly increased activity of GSP and CAT when ED is fed improves the scavenging capacity of the free hydroxyl radicals generated by the radiation, and is an important adjunct to an understanding of ED prophylaxis

The free radical species in polyacrylonitrile fibers induced by γ-radiation and their decay behaviors

International Nuclear Information System (INIS)

Liu Weihua; Wang Mouhua; Xing Zhe; Wu Guozhong

2012-01-01

Free radicals in vacuum, air and oxygen atmospheres were studied using electron spin resonance (ESR). Mainly two types of radicals, namely alkyl radicals and polyimine radicals, are formed in polyacrylonitrile (PAN) fibers after γ-ray irradiation. The G value of the radical formation was calculated to be 2.1 (number of radicals per 100 eV absorbed) in air at room temperature based on the ESR measurements. The radical stability and decay behaviors at room temperature and elevated temperatures were also investigated under different atmospheres. The alkyl radicals were found to be rather stable when stored in vacuum at room temperature, but they decayed via reaction with oxygen when stored in air. The alkyl radicals disappeared completely after a thermal treatment at 110 °C in vacuum, but only 15% of the polyimine radicals decayed; this indicates that polyimine radicals are more stable compared to the alkyl radicals due to their lower mobility. - Highlights: ► Radicals formed by radiation were assigned to polyimine and alkyl radicals. ► G-value of radicals was measured to be 2.1 per 100 eV. ► The radicals were found to be extremely stable in vacuum at room temperature. ► Effect of oxygen on radical decay under various conditions was studied.

Radiation-induced reactions in polydimethyl siloxanes

International Nuclear Information System (INIS)

Menhofer, H.

1988-01-01

The dissertation reports an investigation into the behaviour of polydimethyl soloxanes (PDMS) subject to the radiation field of a 60 Co-γ radiation source at different irradiation conditions. Several different analytical methods have been applied for the detection of chemical changes in the material and their effects on the polymeric segment mobility. Application of the ESR-spintrap technique identifies the primary radicals x CH 3 , -Si x , and -Si-CH 2 x , induced by the radiolysis of the PDMS. The individual rates of radical formation have been found to be strongly dependent on temperature. (orig./LU) [de

Sensitization of microorganisms and enzymes by radiation-induced selective inorganic radical anions

International Nuclear Information System (INIS)

Schubert, J.; Stegeman, H.

1981-01-01

Bacterial survival and enzymatic inactivation were examined following exposure to radiolytically-generated radical anions, X - 2 , where X=Cl, Br, I or CNS - . Depending on pH, radical anions react selectively or specifically with cysteine, tryptophan, tyrosine and histidine. Consequently, when one or more of these amino acids is crucial for enzymatic activity or bacterial survival and is attacked by a radical anion, a high degree or radiosensitization may be realized. Halide radical anions can form free chlorine, bromine or iodine. However, these bactericidal halogens are destroyed by reaction with the hydrated electron, e - sub(aq), or at pHs>9, as occurs, for example, when a medium saturated with nitrous oxide, N 2 O, and e - sub(aq) scavenger, is replaced by nitrogen or oxygen. Increasing concentration of other e - sub(aq) scavengers, such as phosphate buffer, promotes formation of halogen from halides. The conditions producing formation and elimination of halogens in irradiated media must be appreciated to avoid confusing radiosensitization by X 2 to X - 2 . Radiosensitization by radical anions of several microorganisms: S. faecalis, S. typhimurium, E. coli, and M. radiodurens is described. A crucial amino acid for survival of S. faecalis appears to be tyrosine, while both tyrosine and tryptophan seem essential for recovery of S. typhimurium from effects of ionizing radiation. It is postulated that the radiosensitizing action of radical anions involves inhibition of DNA repair of strand-breaks by depriving the cells of energy. In view of the high OH scavenging power of foods, it is concluded that the radiosensitization of bacteria and enzymes in foods by radical anions, except for special cases, is not practical. Rather, radical anions serve to identify crucial amino acids to radiosensitization mechanisms in model systems, and possibly in radiotherapy. (author)

Basic reactions induced by radiation

International Nuclear Information System (INIS)

Charlesby, A.

1980-01-01

This paper summarises some of the basic reactions resulting from exposure to high energy radiation. In the initial stages energy is absorbed, but not necessarily at random, giving radical and ion species which may then react to promote the final chemical change. However, it is possible to intervene at intermediate stages to modify or reduce the radiation effect. Under certain conditions enhanced reactions are also possible. Several expressions are given to calculate radiation yield in terms of energy absorbed. Some analogies between radiation-induced reactions in polymers, and those studied in radiobiology are outlined. (author)

The effect of near-infrared MLS laser radiation on cell membrane structure and radical generation.

Science.gov (United States)

Kujawa, Jolanta; Pasternak, Kamila; Zavodnik, Ilya; Irzmański, Robert; Wróbel, Dominika; Bryszewska, Maria

2014-09-01

The therapeutic effects of low-power laser radiation of different wavelengths and light doses are well known, but the biochemical mechanism of the interaction of laser light with living cells is not fully understood. We have investigated the effect of MLS (Multiwave Locked System) laser near-infrared irradiation on cell membrane structure, functional properties, and free radical generation using human red blood cells and breast cancer MCF-4 cells. The cells were irradiated with low-intensity MLS near-infrared (simultaneously 808 nm, continuous emission and 905 nm, pulse emission, pulse-wave frequency, 1,000 or 2,000 Hz) laser light at light doses from 0 to 15 J (average power density 212.5 mW/cm(2), spot size was 3.18 cm(2)) at 22 °C, the activity membrane bound acetylcholinesterase, cell stability, anti-oxidative activity, and free radical generation were the parameters used in characterizing the structural and functional changes of the cell. Near-infrared low-intensity laser radiation changed the acetylcholinesterase activity of the red blood cell membrane in a dose-dependent manner: There was a considerable increase of maximal enzymatic rate and Michaelis constant due to changes in the membrane structure. Integral parameters such as erythrocyte stability, membrane lipid peroxidation, or methemoglobin levels remained unchanged. Anti-oxidative capacity of the red blood cells increased after MLS laser irradiation. This irradiation induced a time-dependent increase in free radical generation in MCF-4 cells. Low-intensity near-infrared MLS laser radiation induces free radical generation and changes enzymatic and anti-oxidative activities of cellular components. Free radical generation may be the mechanism of the biomodulative effect of laser radiation.

Studying mechanism of radical reactions: From radiation to nitroxides as research tools

Science.gov (United States)

Maimon, Eric; Samuni, Uri; Goldstein, Sara

2018-02-01

Radicals are part of the chemistry of life, and ionizing radiation chemistry serves as an indispensable research tool for elucidation of the mechanism(s) underlying their reactions. The ever-increasing understanding of their involvement in diverse physiological and pathological processes has expanded the search for compounds that can diminish radical-induced damage. This review surveys the areas of research focusing on radical reactions and particularly with stable cyclic nitroxide radicals, which demonstrate unique antioxidative activities. Unlike common antioxidants that are progressively depleted under oxidative stress and yield secondary radicals, nitroxides are efficient radical scavengers yielding in most cases their respective oxoammonium cations, which are readily reduced back in the tissue to the nitroxide thus continuously being recycled. Nitroxides, which not only protect enzymes, cells, and laboratory animals from diverse kinds of biological injury, but also modify the catalytic activity of heme enzymes, could be utilized in chemical and biological systems serving as a research tool for elucidating mechanisms underlying complex chemical and biochemical processes.

Radiation-induced free radical reactions in polymer/drug systems for controlled release: an EPR investigation

Energy Technology Data Exchange (ETDEWEB)

Faucitano, A. E-mail: chemrad@unipv.it; Buttafava, A.; Montanari, L.; Cilurzo, F.; Conti, B.; Genta, I.; Valvo, L

2003-05-01

The primary and secondary free radical intermediates in the gamma radiolysis of poly(D,L-lactide-co-glycolide) (PLGA) and clonazepam loaded PLGA microspheres were investigated by matrix EPR spectroscopy in the temperature range 77-298 K. Drug-polymer interactions were found to be important leading to significant deviations of the G(radicals) from the additivity law. In particular, in the mixed system a stabilization of the polymer matrix with respect to the radiation damage was detected, witnessed by a decrease of the overall polymer radicals yield which is accompanied by an increase of the drug radicals yield. These effects have been attributed to the scavenging properties of the nitro group with respect to electrons and polymer radicals. It is conceivable that such conclusions be of general application for all pharmaceutical formulations containing drugs bearing nitro groups in their chemical structure.

Matrix-isolation studies on the radiation-induced chemistry in H₂O/CO₂ systems: reactions of oxygen atoms and formation of HOCO radical.

Science.gov (United States)

Ryazantsev, Sergey V; Feldman, Vladimir I

2015-03-19

The radiation-induced transformations occurring upon X-ray irradiation of solid CO2/H2O/Ng systems (Ng = Ar, Kr, Xe) at 8-10 K and subsequent annealing up to 45 K were studied by Fourier transform infrared spectroscopy. The infrared (IR) spectra of deposited matrices revealed the presence of isolated monomers, dimers, and intermolecular H2O···CO2 complexes. Irradiation resulted in effective decomposition of matrix-isolated carbon dioxide and water yielding CO molecules and OH radicals, respectively. Annealing of the irradiated samples led to formation of O3, HO2, and a number of xenon hydrides of HXeY type (in the case of xenon matrices). The formation of these species was used for monitoring of the postirradiation thermally induced chemical reactions involving O and H atoms generated by radiolysis. It was shown that the radiolysis of CO2 in noble-gas matrices produced high yields of stabilized oxygen atoms. In all cases, the temperatures at which O atoms become mobile and react are lower than those of H atoms. Dynamics and reactivity of oxygen atoms was found to be independent of the precursor nature. In addition, the formation of HOCO radicals was observed in all the noble-gas matrices at remarkably low temperatures. The IR spectra of HOCO and DOCO were first characterized in krypton and xenon matrices. It was concluded that the formation of HOCO was mainly due to the radiation-induced evolution of the weakly bound H2O···CO2 complexes. This result indicates the significance of weak intermolecular interactions in the radiation-induced chemical processes in inert low-temperature media.

Low dose radiation induced hormesis and its mechanism of free radicals

International Nuclear Information System (INIS)

Zhang Liyuan; Huo Hongmei; Zhang Yusong; Zhao Peifeng; Li Wei; Jiang Jiagui

2008-01-01

Objective: To investigate whether the supernatant (the stimulating fluid) centrifuged from myeloid cells suspension after low dose radiation in vitro can produce hormesis on the normal or radiation damage cells. The mechanism of free radical was probed. Methods: Mouse myeloid cell suspension was irradiated respectively by 0, 2 and 5 Gy, and cultured in vitro. MTT method was used to measure the reproductive activity of cells. Meanwhile, Cytochrome C reduction method was used to determine the concentration of O 2 - . Lastly, the concentration of O 2 - was decreased or increased by adding DPI or PMA, and the effect of such changes on 'the stimulating fluid' was observed. Results: Co-cultured with 'the stimulating fluid', the reproductive activity of the myeloid cells after large dose radiation or the normal myeloid cells were enhanced. Decreasing the concentration of O 2 - ; may degrade the proliferation of the cells after radiation damage; while increasing it may lead to the opposite result. Conclusions: The stimulating fluid can enhance the proliferation of the myeloid cells after radiation damage and also the normal ones. The mechanism of above-mentioned phenomena might be related with the changes of O 2 - concentration. (authors)

Role of free radicals in radiation chemical aging

Energy Technology Data Exchange (ETDEWEB)

Greenstock, C L

1986-01-01

Ionizing radiation initiates chemical changes in DNA, phospholipid membranes and other critical cell targets, that, if allowed to accumulate unrepaired, may lead to aging and other chronic effects. The chemical effects are free radical mediated, the principal damaging species being radical OH and to a lesser extent O2-anion radical and the molecular product H/sub 2/O/sub 2/. Many compounds can act in combination with ionizing radiation, to amplify the potential oxidative stress. Chemicals, ultra-violet light, lipid peroxides and their breakdown products may increase the extent of acute and chronic radiobiological effects.

RADICAL. Radiation information centre with analysing logic

International Nuclear Information System (INIS)

Rantanen, H.

1998-01-01

in an emergency, the production of data is overwhelming and the need of accurate and up-to-date information is essential. In Finland a new system (RADICAL) has been developed in order to automatically collect and maintain an overall view of the radiation situation and to facilitate the analysis of the consequences of any radiation incident. The project was started in the beginning of 1992 and the system was operational in summer 1994. The main objectives of the development process and how they are being fulfilled with the RADICAL system are discussed. (author)

Radiation-induced DNA damage as a function of DNA hydration

International Nuclear Information System (INIS)

Swarts, S.G.; Miao, L.; Wheeler, K.T.; Sevilla, M.D.; Becker, D.

1995-01-01

Radiation-induced DNA damage is produced from the sum of the radicals generated by the direct ionization of the DNA (direct effect) and by the reactions of the DNA with free radicals formed in the surrounding environment (indirect effect). The indirect effect has been believed to be the predominant contributor to radiation-induced intracellular DNA damage, mainly as the result of reactions of bulk water radicals (e.g., OH·) with DNA. However, recent evidence suggests that DNA damage, derived from the irradiation of water molecules that are tightly bound in the hydration layer, may occur as the result of the transfer of electron-loss centers (e.g. holes) and electrons from these water molecules to the DNA. Since this mechanism for damaging DNA more closely parallels that of the direct effect, the irradiation of these tightly bound water molecules may contribute to a quasi-direct effect. These water molecules comprise a large fraction of the water surrounding intracellular DNA and could account for a significant proportion of intracellular radiation-induced DNA damage. Consequently, the authors have attempted to characterize this quasi-direct effect to determine: (1) the extent of the DNA hydration layer that is involved with this effect, and (2) what influence this effect has on the types and quantities of radiation-induced DNA damage

Effect of free radicals and cultivation media on radiation sensitivities of escherichia coli and related bacteria

International Nuclear Information System (INIS)

Ito, Hitoshi

2000-01-01

Effects of gamma-irradiation on some strains of Escherichia coli, Salmonella enteritidis and Staphylococcus aureus were investigated in the presence of N 2 , N 2 O and O 2 and with the hydroxyl radical (OH) scavengers glycerol, polyethylene glycerol and formate. Injured cell membrane of bacteria was detected using with MacConkey agar for E. coli and S. enteritidis and 7% NaCl Triptic soy agar for St. aureus instead of Tryptic soy agar for recovery medium. From this study, addition of glycerol significantly reduced the sensitivity in all of strains, and cell membrane was not injured significantly except in radiation sensitive strain E. coli A4-1. When superoxide radicals (O 2 ) were generated during irradiation in the presence of formate, injured cell membrane increased significantly in all of strains. However, molecular oxygen (O 2 ) and OH radicals also had some effects on the damage of cell membrane. These results suggest that most radiation induced cell lethality was responsible to the cooperative effects of intracellular OH radicals and O 2 on DNA with lessor effect of damage on cell membrane by O 2 radicals, O 2 and OH radicals. On the radiation sensitive strain of E. coli, cell lethality occurred significantly by the injury of cell membrane compared with other strains. (author)

Ionizing radiation induced attachment reactions of nucleic acids and their components

International Nuclear Information System (INIS)

Myers, L.S. Jr.

1975-01-01

An extensive bibliographic review is given of experimental and theoretical data on radiation-induced attachment reactions of nucleic acids and their components. Mechanisms of these reactions are reviewed. The reactions with water, formate, and alcohols, with amines and other small molecules, and with radiation sensitizers and nucleic acid-nucleic acid reactions are discussed. Studies of the reaction mechanisms show that many of the reactions occur by radical-molecule reactions, but radical-radical reactions also occur. Radiation modifiers become attached to nucleic acids in vitro and in vivo and there are indications that attachment may be necessary for the action of some sensitizers. (U.S.)

Effects of gamma radiation induced forced formation of free radicals on the strength of concrete for use in nuclear power plants

Directory of Open Access Journals (Sweden)

Burnham Steven

2017-01-01

Full Text Available In this paper, we present a summary of preliminary experiments and numerical assessments of the effects of gamma radiation induced formation of free radicals in the curing stage of concrete on its characteristics. Substantial literature reports on the damaging effects of long-term and high-dose gamma and neutron exposure on concrete. However, we show that short-term exposure of concrete to gamma radiation can be beneficial in increasing its compressive strength. The effects of exposing to 630 MBq 137Cs the 56 cubes each made of 125 cm3 concrete during the first seven days of curing are compared to another 56 cubes cured by the conventional process. The average compressive strength of the gamma cured cubes is around 8.500 psi, while conventionally cured cubes show the lower average strength of around 6.700 psi. The microstructure of the gamma and conventionally cured concrete cubes is analyzed using a scanning electron microscope. The radiolysis within the microstructure of the concrete cubes is assessed with computational modeling based on Geant4. The production of free radicals from radiolysis is shown to increase with increasing source strength and increasing the time of exposure to gamma radiation. This research shows in general that curing concrete in gamma radiation field provides observable trends toward its increased strength.

ESR-based Identification of Radiation-Induced Free Radicals in Gamma-Irradiated Basil and Clove Using Different Sample Pre-Treatments

International Nuclear Information System (INIS)

Kwak, J.Y.; Ahn, J.J.; Kashif Akram; Kwon, J.H.

2012-01-01

An improved detection of radiation-induced paramagnetic faults was developed to identify the irradiation status of basil and clove. The effectiveness of different sample pretreatments, including freeze-drying (FD), oven-drying (OD), alcoholic-extraction (AE), and water-washing and alcoholic-extraction (WAE), were examined. All non-irradiated samples showed a single central signal (g 0 = 2.006), whereas radicals representing two additional side peaks (g 1 = 2.023 and g 2 = 1.986) with a mutual distance of 6 mT were detected in the irradiated samples. AE and WAE produced the best results for irradiated clove in terms of intensities of radiation-specific ESR signals and their ratios to the central signal. However, FD provided the highest intensities of radiation-specific ESR signals for basil, whereas their ratios to the major signal were better in the cases of AE and WAE. Signal noise, particularly due to Mn 2+ signals, was observed, whereas it decreased in AE and WAE pretreatments. Based on our results, AE and WAE can improve the detection conditions for radiation-specific ESR signals in irradiated samples. (author)

Novel Profluorescent Nitroxides for Monitoring Alkyl Radical Reactions During Radiation Degradation

International Nuclear Information System (INIS)

George, G.

2006-01-01

Hindered amine stabilizers (HAS) are effective at retarding the photo-oxidative and high energy radiation degradation of PP and in certain circumstances, also thermo-oxidative degradation. The effectiveness of HAS as retarders of oxidation relies on the oxidation of the N-C bond by polymer hydroperoxide, ROOH, to form the nitroxyl group -NO which is the scavenger of polymer alkyl radicals, R. This reaction, which produces the alkoxy amine: -NO-R, must be competitive with the reaction of R with oxygen (which gives the chain-carrying peroxy radical, RO 2 ) if this stabilization mechanism is to be important in the inhibition of radiation-induced oxidative degradation of polyolefins by HAS. The rate of this reaction is high and in solution the rate coefficient is from 1 to 9x10 8 l mol - 1 s - 1. The efficient radical trapping by nitroxides has been widely employed in spin-trapping studies by electron spin resonance (esr) spectroscopy]. In addition to the hindered piperidine structure of commercial HAS, more rigid aromatic systems have been studied that are more stable to oxidative degradation and are more efficient at scavenging alkyl radicals. One such family is the iso-indoline nitroxide system, TMDBIO, shown below which, as it contains the phenanthrene fluorophore, is termed phenanthrene nitroxide. This nitroxide only becomes fluorescent when it reacts with alkyl radicals or is reduced and is termed profluorescent. TMDBIO has a vanishingly small fluorescence quantum yield (φ∼10 - 4) due to the enhanced intersystem crossing from the first excited singlet state to the ground state due to electron exchange interactions of the nitroxyl radical. When the nitroxide traps an alkyl radical, R, the resulting alkoxy amine is fluorescent (φ∼10 - 1) and the emission intensity is a measure of the number of reactions that have occurred. This property may be exploited by using quantitative fluorescence spectroscopy to follow the reaction of the nitroxide with alkyl radicals

3 cases of radiation-induced sarcoma

International Nuclear Information System (INIS)

Shiba, Keiichiro; Fukuma, Hisatoshi; Beppu, Yasuo; Hirota, Teruyuki; Shinohara, Norio.

1982-01-01

Criteria for the diagnosis of radiation-induced sarcoma have been previously described. All cases must have a history of irradiation and the second neoplasm must have arisen in the area of the radiation field. A latent period of several years must have elapsed after irradiation before clinical evidence of a second malignant neoplasm. Most important thing is that, all suspected cases must have been proved histologically. We have experienced 3 cases of radiation-induced sarcoma, they were 42-years-old man who developed an osteosarcoma of the lumbar spine at the field of postoperative irradiation for seminoma 7 years previously, 69-years-old woman who developed a malignant fibrous histiocytoma of the buttock at the field of radical radiation for uterine carcinoma 7 years previously and 59-years-old woman who developed an extraskeletal osteosarcoma of the abdominal wall at the field of postoperative irradiation for uterine sarcoma 7 years previously. The last case is very rare and only 8 cases of radiation-induced extraskeletal osteosarcoma have been reported. Since there has been a definite trend in the treatment of cancer toward employing radiation for more favorable cases, in addition to technical improvements in the administration of radiotherapy and more modern equipment, survival data may have been altered considerably in many malignant tumors. Accordingly, more radiation-induced tumors may be encountered in the future. The clinical presentation and histopathology of these radiation-induced sarcomas are presented with a review of the literature. (author)

Hydroxyl-radical-induced oxidation of cyclic dipeptides: Reactions of free peptide radicals and their peroxyl radicals

International Nuclear Information System (INIS)

Mieden, O.J.

1989-01-01

In the course of this study investigations were carried out into the reactions of hydroxyl radicals and hydrogen atoms with cyclic dipeptides as well as the subsequent reactions of peptide radicals and their peroxyl radicals in aqueous solution. The radiolysis products formed in the absence and presence of oxygen or transient metal complexes were characterized and determined on a quantitative basis. The linking of information from product analyses to the kinetic data for transient species obtained by time-resolving UV/VIS and conductivity measurements (pulse radiolysis) as well as computer-assisted simulations of individual events during the reaction permitted an evaluation of the mechanisms underlying the various processes and an identification of interim products with short life-times, which did or did not belong to the group of radicals. Through the characterization of key reactions of radicals and peroxyl radicals of this substance class a major advance has been made towards a better understanding of the role of radicals in the peptide compound and the mechanisms involved in indirect radiation effects on long-chain peptides and proteins. (orig.) [de

Radiation-induced nitration of organic compounds in aqueous solutions

International Nuclear Information System (INIS)

Ershov, B.G.; Gordeev, A.V.; Bykov, G.L.

2009-01-01

Radiation-induced nitration of organic compounds in aqueous solutions was studied. It was found that γ-irradiation of solutions containing acetic and nitric acid and/or their salts gives nitromethane. Dependences of the product yield on the absorbed dose and the contents of components were established. The mechanism of radiation nitration involving radicals is discussed. (author)

Oxidative stress and enzymatic scavenging of superoxide radicals induced by solar UV-B radiation in Ulva canopies from southern Spain

Directory of Open Access Journals (Sweden)

Kai Bischof

2003-09-01

Full Text Available The generation of reactive oxygen species (ROS and scavenging of the superoxide radical by superoxide dismutase (SOD was studied in mat-like canopies of the green macroalga Ulva rotundata Bliding in a tidal brine pond system in southern Spain. Artificial canopies were covered with different cut-off filters, generating different radiation conditions. ROS and SOD were assessed after three days of exposure. ROS induced lipid peroxidation depended on the position of individual thalli within the canopy and on radiation conditions. Samples exposed to the full solar spectrum were most affected, whereas samples either exposed to photosynthetically active radiation (PAR alone or UV radiation without PAR exhibited fewer peroxidation products. The activity of SOD appeared to be controlled by the impinging UV-A and UV-B radiation and also increased in response to oxidative stress. The results provide evidence for additive effects of high PAR and UV-B under field conditions and support the previously proposed hypothesis that UV-B effects are mediated by an inhibition of the xanthophyll cycle, which increases ROS production and, consequently, causes oxidative damage to components of the photosynthetic machinery, such as proteins and pigments.

Primary processes in radiation-induced crosslinking of poly(2-phenylbutadiene)

International Nuclear Information System (INIS)

Yamaoka, Hitoshi; Kato, Kazuo; Okamura, Seizo.

1987-01-01

The radiation-induced crosslinking of poly(2-phenylbutadiene)(PPB) in ethylene dichloride solution was studied in vacuum at 303 K. The G value of the crosslinking was estimated to be about 7.2. In order to detect the reaction intermediates under irradiation, optical absorption spectra in rigid matrices and ESR spectra in bulk were measured. The absorption spectra due to radical cation of PPB and due to α,α-disubstituted benzyl cation were observed in butyl chloride glass. ESR spectra owing to polyenyl type radical was found in the irradiated specimens of PPB and Diels-Alder type dimer of 2-phenylbutadiene. The primary processes in radiation-induced crosslinking of PPB were discussed on the basis of the results obtained. (author)

Radiation-induced glycoside bond breaking in cellulose methyl ethers

International Nuclear Information System (INIS)

Petryaev, E.P.; Boltromeyuk, V.V.; Kovalenko, N.I.; Shadyro, O.I.

1988-01-01

Radiation-induced destruction of cellulose methyl ethers of different degree of esterification in aqueous solutions with and without acceptors: (N 2 O, O 2 , H 2 O + , Co(2), Cu(2)) is investigated. It is established that OH radicals make main contribution into radiolytic transformations of cellulose ethers in aqueous solutions. Reactions of radicals with free valency on carbon atoms containing secondary nonsubstituted hydroxyl groups lead also to glycoside bond breaking besides the reaction of β-fragmentation and hydrolysis of radicals with an unpaired electron localized near C 1 , C 4 , C 5 aroms

Mechanisms of free radical-induced damage to DNA.

Science.gov (United States)

Dizdaroglu, Miral; Jaruga, Pawel

2012-04-01

Endogenous and exogenous sources cause free radical-induced DNA damage in living organisms by a variety of mechanisms. The highly reactive hydroxyl radical reacts with the heterocyclic DNA bases and the sugar moiety near or at diffusion-controlled rates. Hydrated electron and H atom also add to the heterocyclic bases. These reactions lead to adduct radicals, further reactions of which yield numerous products. These include DNA base and sugar products, single- and double-strand breaks, 8,5'-cyclopurine-2'-deoxynucleosides, tandem lesions, clustered sites and DNA-protein cross-links. Reaction conditions and the presence or absence of oxygen profoundly affect the types and yields of the products. There is mounting evidence for an important role of free radical-induced DNA damage in the etiology of numerous diseases including cancer. Further understanding of mechanisms of free radical-induced DNA damage, and cellular repair and biological consequences of DNA damage products will be of outmost importance for disease prevention and treatment.

Resonance Raman Spectroscopy of Free Radicals Produced by Ionizing Radiation

DEFF Research Database (Denmark)

Wilbrandt, Robert Walter

1984-01-01

Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p-nitrobenzylchloride and......Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p......-nitrobenzylchloride and subsequent formation of the p-nitrobenzyl radical and the reaction of p-nitrotoluene with O– are studied by resonance Raman and optical absorption spectroscopy....

Ultrasound-induced radical polymerization

NARCIS (Netherlands)

Kuijpers, M.W.A.; Kemmere, M.F.; Keurentjes, J.T.F.

2004-01-01

Sonochemistry comprises all chemical effects that are induced by ultrasound. Most of these effects are caused by cavitations, ie, the collapse of microscopic bubbles in a liquid. The chemical effects of ultrasound include the formation of radicals and the enhancement of reaction rates at ambient

Radiation-induced DNA-protein cross-links: Mechanisms and biological significance.

Science.gov (United States)

Nakano, Toshiaki; Xu, Xu; Salem, Amir M H; Shoulkamy, Mahmoud I; Ide, Hiroshi

2017-06-01

Ionizing radiation produces various DNA lesions such as base damage, DNA single-strand breaks (SSBs), DNA double-strand breaks (DSBs), and DNA-protein cross-links (DPCs). Of these, the biological significance of DPCs remains elusive. In this article, we focus on radiation-induced DPCs and review the current understanding of their induction, properties, repair, and biological consequences. When cells are irradiated, the formation of base damage, SSBs, and DSBs are promoted in the presence of oxygen. Conversely, that of DPCs is promoted in the absence of oxygen, suggesting their importance in hypoxic cells, such as those present in tumors. DNA and protein radicals generated by hydroxyl radicals (i.e., indirect effect) are responsible for DPC formation. In addition, DPCs can also be formed from guanine radical cations generated by the direct effect. Actin, histones, and other proteins have been identified as cross-linked proteins. Also, covalent linkages between DNA and protein constituents such as thymine-lysine and guanine-lysine have been identified and their structures are proposed. In irradiated cells and tissues, DPCs are repaired in a biphasic manner, consisting of fast and slow components. The half-time for the fast component is 20min-2h and that for the slow component is 2-70h. Notably, radiation-induced DPCs are repaired more slowly than DSBs. Homologous recombination plays a pivotal role in the repair of radiation-induced DPCs as well as DSBs. Recently, a novel mechanism of DPC repair mediated by a DPC protease was reported, wherein the resulting DNA-peptide cross-links were bypassed by translesion synthesis. The replication and transcription of DPC-bearing reporter plasmids are inhibited in cells, suggesting that DPCs are potentially lethal lesions. However, whether DPCs are mutagenic and induce gross chromosomal alterations remains to be determined. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of sulfhydryls on potentiation of radiation-induced cell lethality by substituted anthraquinones

International Nuclear Information System (INIS)

Kimler, B.F.

1984-01-01

The effects of various substituted anthraquinones (SAQ's) and Adriamycin (ADR) were investigated in cultured Chinese hamster V79 cells. These drugs cause a potentiation of radiation-induced cell lethality, albeit by different mechanisms. One possibility is that these components operate through the production of free radicals which then produce DNA strand breaks and crosslinks. If so, then one should be able to change the degree of cell kill by modifying sulfhydryl (SH) levels such that free radical processes are altered. Diamide, buthionine-S, R-sulfoximine, and N-ethylmaleimide (NEM) were used to reduce intracellular SH levels. Cysteamine and dithiotheitol were used to increase SH levels. In general, altered SH levels did not affect SAQ-induced cytotoxicity at low drug concentrations. When drug-tested cells were also irradiated, survival levels were generally those predicted from assuming purely additive interactions. On the other hand, survival after treatment with high concentrations of ADR and one other SAQ were decreased by concomitant treatment with NEM. Since altered SH levels do not produce changes in the potentiation of radiation-induced cell lethality by SAQs, it is concluded that free radicals are not involved in this potentiation. A free radical-mediated process may be involved in the cytotoxicity induced by ADR and other SAQs; however, it is not a simple process

Involvement of hydroxyl radicals in the release by ionizing radiation of a cell surface nuclease from Micorcoccus radiodurans

International Nuclear Information System (INIS)

Mitchel, R.E.J.

1975-01-01

The ionizing radiation-induced release of a surface exonuclease from Micrococcus radiodurans is to a large extent inhibited by the removal of water. Irradiation of a cell suspension saturated with O 2 (an effective aqueous electron and hydrogen atom scavenger) allows the same release as irradiation in the presence of N 2 . Ethanol (a good hydroxyl radical scavenger) protects the enzyme from release. These data suggest that hydroxyl radicals produced by the radiolysis of water are important releasing agents. Hydroxyl radicals produced by the ultraviolet decomposition of H 2 O 2 were effective in releasing the enzyme

Primary processes of the radiation-induced cationic polymerization of aromatic olefins studied by pulse radiolysis

International Nuclear Information System (INIS)

Brede, O.; Boes, J.; Helmstreit, W.; Mehnert, R.

1982-01-01

By pulse radiolysis of solutions of aromatic olefins (styrene, 1-methylstyrene, 1,1-diphenylethylene) in non-polar solvents (cyclohexane, carbon tetrachloride, n-butylchloride) the mechanism and kinetics of primary processes of radiation-induced cationic polymerization were investigated. In cyclohexane, radical cations of the olefins are generated by charge transfer from solvent cations. These cations dimerize in a diffusion-controlled reaction. The next step of chain-growth is slower by 3 to 4 orders of magnitude. In carbon tetrachloride and in n-butyl chloride growing olefin cations are produced by a reaction of radical cations with solvent as well as by addition of solvent carbonium ions to the monomer. In strongly acidic aqueous solution of olefins radical cations produced indirectly from hydroxycyclohexadienyl radicals dimerize and react in a subsequent step by deprotonation forming non-saturated dimer radicals. The reaction mechanism established shows that in the case of radiation-induced cationic polymerization it is not possible to define a uniform first step of the chain reaction. (author)

The research progress of several kinds of free radical scavengers

International Nuclear Information System (INIS)

Qian Liren; Huang Yuecheng; Cai Jianming

2009-01-01

Ionization radiation can generate free radicals in biological system, which could induce lipid peroxi-dation, biomacromolecule and biomembrane damage, lost of cell function, cell cycle disturbance, genetic mutation and so on. The scavenging free radicals can protect organism from radiation damage. Many radio-protective agents, such as amylase, hydroxyl-benzene derivatives, hormone, vitamin, have great abilities to protect organism from radiation via scavenging free radicals. In this paper, we mainly review the free radical scavenging effects of several kinds of radio-protective agents. (authors)

Radioprotection by butylated hydroxytoluene against radiation induced genetic and lethal effects in yeast

International Nuclear Information System (INIS)

Anjaria, Kshiti B.; Shirsath, Kapil B.; Sreedevi, B.

2012-01-01

Butylated hydroxytoluene (BHT) is a phenolic antioxidant which is used widely in food industry as a food preservative for fats and oils; in plastics and also in cosmetics and fragrances. Generally it is considered harmless, however BHT has also shown potentiation of radiation effects in some studies. The objective of this study was to test the modifying properties of BHT in a eukaryotic model system comprising of Saccharomyces cerevisiae D7, a diploid yeast strain, against the genotoxic effects induced by 60 Co gamma radiation. Log phase cells were exposed to 100 Gy of radiation in the absence or presence of 0.025-0.25 mM BHT. In another set of experiments, log phase cells were exposed to 400 Gy of radiation in the absence or presence of 0.025 mM BHT. Cells were washed and plated. The results indicated that presence of BHT reduced the frequencies of gene conversion and back mutation as well as cell killing induced by radiation. The results obtained in the present study can be explained on the basis of potent radical scavenging ability of BHT, which is a well known standard antioxidant and whose free radical scavenging ability has been very well established and documented using stable free radical DPPH. (author)

Chemical determination of free radical-induced damage to DNA.

Science.gov (United States)

Dizdaroglu, M

1991-01-01

Free radical-induced damage to DNA in vivo can result in deleterious biological consequences such as the initiation and promotion of cancer. Chemical characterization and quantitation of such DNA damage is essential for an understanding of its biological consequences and cellular repair. Methodologies incorporating the technique of gas chromatography/mass spectrometry (GC/MS) have been developed in recent years for measurement of free radical-induced DNA damage. The use of GC/MS with selected-ion monitoring (SIM) facilitates unequivocal identification and quantitation of a large number of products of all four DNA bases produced in DNA by reactions with hydroxyl radical, hydrated electron, and H atom. Hydroxyl radical-induced DNA-protein cross-links in mammalian chromatin, and products of the sugar moiety in DNA are also unequivocally identified and quantitated. The sensitivity and selectivity of the GC/MS-SIM technique enables the measurement of DNA base products even in isolated mammalian chromatin without the necessity of first isolating DNA, and despite the presence of histones. Recent results reviewed in this article demonstrate the usefulness of the GC/MS technique for chemical determination of free radical-induced DNA damage in DNA as well as in mammalian chromatin under a vast variety of conditions of free radical production.

The effect of thermal treatment on radiation-induced EPR signals in tooth enamel

International Nuclear Information System (INIS)

Vorona, I.P.; Ishchenko, S.S.; Baran, N.P.

2005-01-01

The effect of thermal treatment on the radiation-induced EPR spectrum of tooth enamel was studied. Annealing before sample irradiation was found to increase enamel radiation sensitivity by more than 40%. Depending on the annealing conditions the EPR signals of three supplementary radiation radicals were observed in addition to the main signal caused by CO 2 - radicals. It was found that the presence of these signals in the enamel EPR spectra provides evidence of sample annealing. The possibility of obtaining information about sample history by studying the additional EPR signals is discussed. It can be important to EPR dating and EPR dosimetry

ESR Study Applied To Thermal Stability Of Radiation-Induced Species Of Solid Ketoprofen

International Nuclear Information System (INIS)

Maltar-Strmecki, N.; Katusin-Razem, B.; Razem, D.

2015-01-01

Ketoprofen [2-(3-benzoylphenyl) propionic acid] is a non-steroidal anti-inflammatory drug. It has been widely used in human and veterinary medicine. Radiation processing of drugs and its ingredients is recognized as a safe and effective method among the existing technologies for sterilization and protocols that can be found in ISO 11137-1. Radiosterilization of drugs or other medical products by a suitable dose of ionizing radiation conducted in an appropriate environment ensures sterile conditions by destroying or removing vegetative and sporulating microbes from the ingredients or environment. In earlier studies the effects of gamma radiation was evaluated by selected physico-chemical methods and the observations showed that solid ketoprofen is relatively stable toward ionizing irradiation and that radiosterilization might be a suitable method for the sterilization of solid ketoprofen. The studies reported in this work were undertaken to analyse thermal stability of free radicals by accelerated aging method with a view to the determination of shelf-life. The expiration date (shelf-life) of a product is based on evaluation of both, thermal stability of free radicals, as well as on the time evolution of stable radiolysis products. Namely, storage time is determined by the time required by any degradation product in the dosage form to achieve a sufficient level to represent a risk to the patient. This work shows that ESR spectroscopy provides means for determination of thermal stability of radicals induced by gamma-irradiation in solid drugs. Therefore, despite the complex mixture of individual free radicals induced by gamma-irradiation in solid ketoprofen, the overall lifetime of free radicals could be determined by using isothermal and isochronal annealing. This study shows that radicals induced by gamma-irradiation in solid ketoprofen are stable for at least about 6 months. (author).

Some biochemical consequences of the spatial distribution of ionizing radiation-produced free radicals

International Nuclear Information System (INIS)

Ward, J.F.

1981-01-01

Ionizing radiation deposits energy nonhomogeneously in the medium through which it passes. Mozumder and Magee (Radiat. Res. 28, 203-214(1966)) have classified the events as spurs, blobs, and short tracks. These are defined by size and amount of energy deposited. Thus the initial chemically reactive species are distributed in an inhomogeneous manner. In these volumes of high radical concentration, radical-radical reactions can occur which can only be scavenged by solutes at high concentration. Making the reasonable assumption that similar events occur intracellularly, the consequences of such events must be considered. In the case of DNA, several authors have shown that OH radicals diffuse only tens of angstroms prior to reaction. In the volume from which these radicals originate, DNA is necessarily at high concentration and consequently will interact with the radicals formed in the spur, etc. Such events are probably the source of radiation-production double-strand breaks in cellular DNA. However, the radicals cause other types of damage than strand breaks-potential strand breaks and base damage. An attempt is made to present the interrelation of multiply damaged sites - their constitution, the problems they present to cell repair mechanisms, and their possible relationship to cell survival

Caloric stimulation with near infrared radiation does not induce paradoxical nystagmus.

Science.gov (United States)

Walther, L E; Asenov, D R; Di Martino, E

2011-04-01

Near infrared radiation can be used for warm stimulation in caloric irrigation of the equilibrium organ. Aim of this study was to determine whether near infrared radiation offers effective stimulation of the vestibular organ, whether it is well tolerated by the patients and especially whether it is a viable alternative to warm air stimulation in patients with defects of the tympanic membrane and radical mastoid cavities. Patients with perforations of the tympanic membrane (n = 15) and with radical mastoid cavities (n = 13) were tested both with near infrared radiation and warm dry air. A caloric-induced nystagmus could be seen equally effectively and rapidly in all patients. Contrary to stimulation with warm dry air, no paradoxical nystagmus was observed following caloric irrigation with a warm stimulus (near infrared radiation). Results of a questionnaire showed excellent patient acceptance of near infrared stimulation with no arousal effects or unpleasant feeling. In conclusion, near infrared radiation proved to be an alternative method of caloric irrigation to warm dry air in patients with tympanic membrane defects and radical mastoid cavities. Near infrared radiation is pleasant, quick, contact free, sterile and quiet. With this method an effective caloric warm stimulus is available. If near infrared radiation is used for caloric stimulus no evaporative heat loss occurs.

Notes on free radicals in the field of human and environmental protection against ionizing radiations

International Nuclear Information System (INIS)

Bittel, R.

It is well known that ionizing radiations, in vitro and in vivo produce, free radicals which may be considered as mediators between physical agents and biological targets. Some aspects of this vast problem are accentuated. Ionizing radiations act either directly on the organic molecules of tissues or indirectly by creating, in the surroundings and in tissular water, inorganic free radicals which act on biochemical molecules to gives new radicals. Analysis of the free radical initiation phenomenon in vivo shows that many initiating agents exist, ionizing radiations representing only one group. The role of oxydants, especially oxydising polluants, and the part played by various enzyme systems (super-oxide dismutase, oxydases etc...) are emphasized. After propagation the chain reactions end in combinations between radicals are stopped by certain organic molecules (radical scavengers). Examples are given (free radical formation from compounds of great biological importance: puric and pyrimidic bases, nucleic acids in particular). These aspects are discussed from the viewpoint of their effects on human and environmental protection against both ionizing radiations and certain chemical pollution [fr

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

Science.gov (United States)

Lorimore, S A; Wright, E G

2003-01-01

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

Initial decay process of radicals induced in irradiated food

International Nuclear Information System (INIS)

Kaimori, Yoshihiko; Sakamoto, Yuki; Nakamura, Hideo; Ukai, Mitsuko; Kikuchi, Masahiro; Shimoyama, Yuhei; Kobayashi, Yasuhiko; Kameya, Hiromi

2011-01-01

In order to determine radial decay behaviors of γ-irradiated food, we analyzed radicals in the food using ESR. We detected the ESR signal of specimens just several minutes after irradiation. The singlet signal intensity at g=2.0, originated from organic free radicals was increased as followed by the increasing radiation dose. Singlet signal intensity that increased by γ-irradiation was decreased with time. The phenomena of decay of the ESR singlet signal showed two phase that are rapid decay and slow decay. It was suggested that those two phase decay is due to at least the two radical species. Also we concluded that after three hours of radiation treatment long life radical as ESR signal intensity was detected in irradiated specimen; black pepper, green coffee bean and ginseng, showed the same decay phenomena. But the signal intensity of irradiated black pepper was three times larger than that of irradiated green coffee bean and irradiated ginseng. (author)

Hydroxyl radical induced cross-linking of cytosine and tyrosine in nucleohistone

International Nuclear Information System (INIS)

Gajewski, E.; Dizdaroglu, M.

1990-01-01

Hydroxyl radical induced formation of a DNA-protein cross-link involving cytosine and tyrosine in nucleohistone in buffered aqueous solution is reported. The technique of gas chromatography-mass spectrometry was used for this investigation. A γ-irradiated aqueous mixture of cytosine and tyrosine was first investigated in order to obtain gas chromatographic-mass spectrometric properties of possible cytosine-tyrosine cross-links. One cross-link was observed, and its structure was identified as the product from the formation of a covalent bond between carbon 6 of cytosine and carbon 3 of tyrosine. With the use of gas chromatography-mass spectrometry with selected-ion monitoring, this cytosine-tyrosine cross-link was identified in acidic hydrolysates of calf thymus nucleohistone γ-irradiated in N 2 O-saturated aqueous solution. The yield of this DNA-protein cross-link in nucleohistone was found to be a linear function of the radiation dose in the range of 100-500 Gy (J·kg -1 ). This yield amounted to 0.05 nmol·J -1 . Mechanisms underlying the formation of the cytosine-tyrosine cross-link in nucleohistone were proposed to involve radical-radical and/or radical addition reactions of hydroxyl adduct radicals of cytosine and tyrosine moieties, forming a covalent bond between carbon 6 of cytosine and carbon 3 of tyrosine. When oxygen was present in irradiated solutions, no cytosine-tyrosine cross-links were observed

The Evaluation of Melatonin Effect Against The Early Effect of Ionizing Radiation Induced Lung Injury

Directory of Open Access Journals (Sweden)

raziyeh tahamtan

2014-06-01

Results: the results indicated that radiation increases the collapse and fibrosis and cause the abundance of macrophage compared to control group (p<0.05. Oral administration of melatonin before radiation therapy significantly increased the lymphocyte and macrophage frequency (p<0.001 and decreased the RBC (p<0.05 frequency compared to the radiation group. Conclusion: According to the results, melatonin can prevent early damages in irradiated lungs. Free radicals cause cytotoxicity and melatonin can directly decrease the radiation induced cell damages by converting the free radicals to non- toxic compounds and also through the activation of the major antioxidant enzymes.

Effect of dose on radiation-induced conductivity in polymers

International Nuclear Information System (INIS)

Tyutnev, A.P.; Saenko, V.S.; Pozhidaev, E.D.; Ikhsanov, R.Sh.

2007-01-01

Numerical simulation of radiation-induced conductivity in polymers upon long-term irradiation on the basis of the generalized Rose-Fowler-Vaisberg model, which allows for both dipolar carrier transport and generation of radiation traps during irradiation, was performed. The unusual properties of radiation-induced conductivity, such as the appearance of a maximum on current transients, the absence of a steady state, and a substantial difference between these curves for the first and subsequent irradiation, are rationalized in terms of the formation of free radicals, the major feature of radiolysis in the chemical aspect. This interpretation does not require the involvement of degradation or crosslinking processes, unlike other interpretations that appear in the literature. With the use of low-density polyethylene as an example, it was shown that radiation-induced conductivity both upon pulse and continuous irradiation can satisfactorily be described with the unified set of parameters of the generalized Rose-Fowler-Vaisberg model [ru

Detection of the Level of Reactive Oxygen Species Induced by Ionizing Radiation in Cells

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Kyu; Chung, Dong Min; Kim, Jin-Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

By definition, the direct effect is referred to interaction between photon and DNA molecule, whereas the indirect effect is mediated by the reactive oxygen species (ROS) generated by radiolysis and subsequent reaction. It has been reported that ROS produced after exposure to IR can react with cellular materials such as DNA, proteins, carbohydrates and lipids. ROS is free radicals such as the superoxide anion, hydroxyl radicals and the non-radical hydrogen peroxide. Cells generate ROS during aerobic metabolism. Excessive production of ROS can lead to oxidative stress, genetic alteration and even cell death. It has been reported that ROS plays a critical role in radiation-induced cell injury. Thus, it is of great interest to determine the radiation-induced ROS level. Many kinds of methods to detect the level of ROS have been developed so far. There were random changes of fluorescence intensity in the treatment after irradiation. This result meant that this protocol was not appropriate for determination of radiation-induced ROS. On the other hand, the fluorescence intensity was increased in a dose-dependent manner when the cells were treated with the DCFH-DA solution before irradiation. Conclusions can be drawn from the experimental results of this study. In order to properly measure the ROS level in the cells exposed to ionizing radiation, the cells should be treated with the DCFH-DA solution before irradiation.

Radiation-initiated free-radical fragmentation of biologically active glycerides

International Nuclear Information System (INIS)

Akhrem, A.A.; Kisel', M.A.; Shadyro, O.I.; Yurkova, I.L.

1993-01-01

Oxidation reactions of the free-radical type play a decisive role in the initial processes of radiation damage. The most suitable substrates for such reactions are lipids. Lipids are a basic structural element of biomembranes and are involved in the barrier function and biocatalytic activity of such membranes. Free-radical degradation of membrane lipids can lead to serious damage and ultimately to destruction of the living cell. A well-studied type of free-radical conversion of lipids is oxidation of polyunsaturated fatty acid residues, so-called peroxide oxidation of lipids. In this paper, using as examples dimyristoylphosphatidyl glycerol (DMPG), monoglycerides, and glycerophosphate, the authors investigated the possibility of free-radical degradation in compounds of a lipid nature containing the α,β-bifunctional group

Occupational exposure to ionizing radiation as a risk factor for free-radicals mediated diseases

International Nuclear Information System (INIS)

Djurovic, B.; Spasic-Jokic, V.; Selakovic, V.

2007-01-01

Complete text of publication follows. It was experimentally showed, that the exposure to low doses of ionizing radiation (IR) result in over-production of oxygen derived free radicals with inverse dose-rate effect. The oxidative stress that follows, especially cell membrane damage, was considered by Petkau, as crucial step in the induction of radiation injuries. From clinical research and practice with other unexposed patients is known that this type of cell damage can lead to an impairment of cellular function and can cause many free-radicals mediated diseases, such as atherosclerosis, damage of heart muscles, inflammatory and immuno-reactive lesions, senile dementia, cancer, etc. The aim of this paper is to investigate if occupational exposure to low doses of IR change the redox status of exposed personnel, and if so, is it the additional risk factor for free-radicals mediated diseases. Subjects: 77 medical workers, devided in two groups: 44 occupationally exposed to ionizing radiation (E), and 33 controls (C), matched in age, gender, habits-daitary, alcohol consumption, smoking and exposure time, were examined. Methods: Radiation dose accumulated over years was calculated on the basis of individual TL-dose records. Superoxide-anion and MDA production, as well as SOD (MnSOD, CuZnSOD) and GSH activity were determined in blood samples spectrophotometrically. Results: Significantly higher incidence of cataract, and higher, but not significant, incidence of cardiovascular diseases was noticed in exposed. Our results also confirmed significantly higher superoxide and MDA production (p=0.0049, 0.000028, respectively), as well as, increased activity of MnSOD and CuZnSOD (p0.0105, 0.001, respectively), and decreased level of GSH (p=0.0599) in exposed. Conclusions: Our results showed that low doses of IR could induce oxidative stress and for that reason could be considered as additional risk factor for free radical-mediated diseases. Further epidemiological studies are

Radiation-induced enhancement of enzymatic cell lysis of Micrococcus radiodurans

International Nuclear Information System (INIS)

Watanabe, H.; Takehisa, M.; Iizuka, H.

1981-01-01

The intact cells of M. radiodurans were rendered sensitive to the action of lytic enzyme (P2-2 enzyme) by irradiation. The radiation-induced enhancement of cell lysis with P2-2 enzyme was completely prevented by the addition of t-butanol and irradiation at liquid nitrogen temperature. These results indicate that the enhancement is due to indirect action resulting from OH radicals. Cell lysis by lysozyme was enhanced only when the cells were irradiated under N 2 O. The enhancement of cell lysis with lysozyme was also prevented by adding alcohols. On the other hand, when lipid components in cells were removed by extraction with n-butanol, the radiation-induced enhancement of cell lysis with P2-2 enzyme and lysozyme was not observed. From these results it is concluded that the enhancement of enzymatic cell lysis by irradiation is attributable to alteration in the lipid-rich layer of the cell wall caused by OH radicals

Radiation-induced enhancement of enzymatic cell lysis of Micrococcus radiodurans

Energy Technology Data Exchange (ETDEWEB)

Watanabe, H.; Takehisa, M. [Japan Atomic Energy Research Inst., Takasaki, Gunma, Takasaki Radiation Chemistry Research Establishment (Japan); Iizuka, H.

1981-10-15

The intact cells of M. radiodurans were rendered sensitive to the action of lytic enzyme (P2-2 enzyme) by irradiation. The radiation-induced enhancement of cell lysis with P2-2 enzyme was completely prevented by the addition of t-butanol and irradiation at liquid nitrogen temperature. These results indicate that the enhancement is due to indirect action resulting from OH radicals. Cell lysis by lysozyme was enhanced only when the cells were irradiated under N{sub 2}O. The enhancement of cell lysis with lysozyme was also prevented by adding alcohols. On the other hand, when lipid components in cells were removed by extraction with n-butanol, the radiation-induced enhancement of cell lysis with P2-2 enzyme and lysozyme was not observed. From these results it is concluded that the enhancement of enzymatic cell lysis by irradiation is attributable to alteration in the lipid-rich layer of the cell wall caused by OH radicals.

Radiation-induced lipid peroxidation: influence of oxygen concentration and membrane lipid composition

International Nuclear Information System (INIS)

Wolters, H.; Tilburg, C.A.M. van; Konings, A.W.T.

1987-01-01

Radiation -induced lipid peroxidation phospholipid liposomes was investigated in terms of its dependence on lipid composition and oxygen concentration. Non-peroxidizable lipid incorporated in the liposomes reduced the rate of peroxidation of the peroxidizable phospholipid acyl chains, possibly by restricting the length of chain reactions. The latter effect is believed to be caused by interference of the non-peroxidizable lipids in the bilayer. At low oxygen concentration lipid peroxidation was reduced. The cause of this limited peroxidation may be a reduced number of radical initiation reactions possibly involving oxygen-derived superoxide radicals. Killing of proliferating mammalian cells, irradiated at oxygen concentrations ranging from 0 to 100%, appeared to be independent of the concentration of peroxidizable phospholipids in the cell membranes. This indicates that lipid peroxidation is not the determining process in radiation-induced reproductive cell death. (author)

Radiation-induced polymerisation of 2,3-dihydrofuran: free-radical or cationic mechanism?

International Nuclear Information System (INIS)

Janovsky, Igor; Naumov, Sergej; Knolle, Wolfgang; Mehnert, Reiner

2005-01-01

Concentrated (10 mol%) solutions of 2,3-dihydrofuran in CFCl 2 CF 2 Cl matrix were irradiated at 77 K and several intermediates (dimer radical cation, dihydrofuryl radical, and polymer radicals) were observed by low-temperature EPR spectroscopy. The irradiated solutions yielded after melting a polymeric product, which was characterised by IR spectroscopy and gel permeation chromatography. The polydisperse polymer is assumed to be formed mainly by a cationic process initiated by a dimer carbocation. The free-radical mechanism via the dihydrofuryl radical leads to low molecular weight oligomers only. Quantum chemical calculations support the interpretation of the experimental results

Primary processes of the radiation-induced cationic polymerization of aromatic olefins studied by pulse radiolysis

International Nuclear Information System (INIS)

Brede, O.; Boes, J.; Helmstreit, W.; Mehnert, R.

1981-01-01

By pulse radiolysis of solutions of aromatic olefins (styrene, 1-methylstyrene, 1,1-diphenylethylene) in nonpolar solvents (cyclohexane, carbon tetrachloride, n-butyl chloride) the mechanism and kinetics of primary processes of radiation-induced cationic polymerization were investigated. In cyclohexane, radical cations of the olefins are generated by charge transfer from solvent cations (k about 10 11 l mol -1 s -1 ). These cations dimerize in a diffusion-controlled reaction (k approximately 10 10 l mol -1 s -1 ). The next step of chain-growth is slower by 3 to 4 orders of magnitude. Furthermore, in carbon tetrachloride and in n-butyl chloride growing olefin cations are produced by a reaction of the radical cations with the solvent as well as by addition of solvent carbonium ions to the monomer. In strongly acidic aqueous solution of olefins radical cations produced indirectly from hydroxycyclohexadienyl radicals dimerize and react in a subsequent step by deprotonation forming non-saturated dimer radicals. The established reaction mechanism shows that in the case of radiation-induced cationic polymerization it is not possible to define a uniform first step of the chain reaction. (author)

Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

International Nuclear Information System (INIS)

Szabó, László; Tóth, Tünde; Homlok, Renáta; Rácz, Gergely; Takács, Erzsébet; Wojnárovits, László

2014-01-01

Ionizing radiation induced degradation of acetylsalicylic acid, its hydrolysis product salicylic acid and a salicylic acid derivative 5-sulpho-salicylic acid, was investigated in dilute aqueous solutions by UV–vis spectrophotometry, HPLC separation and diode-array or MS/MS detection, chemical oxygen demand, total organic carbon content and by Vibrio fischeri toxicity measurements. Hydroxyl radicals were shown to degrade these molecules readily, and first degradation products were hydroxylated derivatives in all cases. Due to the by-products, among them hydrogen peroxide, the toxicity first increased and then decreased with the absorbed dose. With prolonged irradiation complete mineralization was achieved. - Highlights: • In OH induced reactions of salicylates first products are hydroxylated derivatives. • With prolonged irradiation dihydroxy derivatives also form. • In aerated solutions the one-electron oxidant OH induces 3–4 oxidations. • Toxicity first increases and then decreases with dose mainly due to H 2 O 2 formation. • The toxicity in tap water is smaller than in pure water

Free radicals created by radiation and aging symptoms

International Nuclear Information System (INIS)

Ashry, O.M.

2012-01-01

The universality of aging implies that its cause is basically the same in all species. A free radical hypothesis of aging has been proposed that the free radicals produced during normal metabolism of the cell over time damage DNA and other macromolecules leading to degenerative diseases, malignancies, and eventual death of vital cells which in turn causes aging and death of the organism. This hypothesis is supported by several observations. Radiation produces its biologic effect through free radical formation and causes premature aging. Second, the age pigment lipo fuscin is associated with lipid peroxidation. The hypothesis that oxygen radicals play a role in aging is also supported by the observation that, in general, long-lived species produce less endogenous free oxygen radicals because of their lower metabolic rate. Long-lived animals also have more superoxide dismutase than do their short-lived counterparts, and animal species with the longest lifespan have the highest levels of superoxide dismutase. Oxidative DNA damage is rapidly and effectively repaired. It has been estimated that there are several thousand oxidative DNA damage sites in a human cell every day, and the majority of these are repaired. However, a small fraction of unrepaired lesions could cause permanent changes in DNA and might be a major contributor to aging and cancer. A consequence of the free radical hypothesis of aging is the idea that free radical scavenging agents might be used to prevent aging. (author)

Studies of radiation-produced radicals and radical ions. Progress report, June 1, 1981-August 31, 1982

International Nuclear Information System (INIS)

Williams, T.F.

1982-01-01

The discovery and characterization of novel radical ions produced by the γ irradiation of solids continues to be a fertile field for investigation. This Progress Report describes the generation and ESR identification of several new paramagnetic species, some of which have long been sought as important intermediates in radiation chemistry. We have also contributed to a general theoretical problem in ESR spectroscopy. Solid-state studies of electron attachment reactions, both non-dissociative and dissociative, reveal interesting structural and chemical information about the molecular nature of these processes for simple compounds. In particular, ESR measurements of the spin distribution in the products allow a fairly sharp distinction to be drawn between radical anions and radical-anion pairs or adducts. Dimer radical anion formation can also take place but the crystal structure plays a role in this process, as expected. Some radical anions undergo photolysis to give radical-anion pairs which may then revert back to the original radical anion by a thermal reaction. The chemistry of these reversible processes is made more intricate by a competing reaction in which the radical abstracts a hydrogen atom from a neighboring molecule. However, the unraveling of this complication has also served to extend our knowledge of the role of quantum tunneling in chemical reactions. The results of this investigation testify to the potential of solid-state techniques for the study of novel and frangible radical ions. Progress in this field shows no sign of abating, as witness the recent discovery of perfluorocycloalkane radical anions and alkane radical cations

EPR study of N+-ion-induced free radical formation in antibiotic-producers

International Nuclear Information System (INIS)

Xie Liqing; Zhang Yinfen; Chen Ruyi; Gao Juncheng; Zhang Peiling; Ying Hengfeng.

1995-01-01

Under the room temperature, electron paramagnetic resonance (EPR) spectrometer was used to study free radical formation in antibiotic-producers in order to investigate antibiotic-producer mutagenic breeding, which were induced by N + ion implanting into antibiotic-producers (e.g., Streptomyces ribosidificus, Streptomyces kanamyceticus and the phage-resistant culture of Streptomyces kanamyceticus). The results show that a lot of free radicals can be induced by N + ion implanting into antibiotic-producers, and the yields of the free radicals increase with implanting dose. The death rate of antibiotic-producers rises due to the increase of N + -ion-induced free radical yields. (author)

Reactions of OH-radicals with hydroxylated and methoxylated benzoic acids and cinnamic acids. Radiation-induced chemical changes in mushrooms

International Nuclear Information System (INIS)

Gaisberger, B.

2001-05-01

In the first part of this work the radiation induced chemical changes of methoxylated and hydroxylated benzoic acids and cinnamic acids were investigated. Methoxylated compounds were also used as model components for acid derivatives with no free-OH groups. The latter are essentials parts of vegetable foodstuff. A comparison of the radiolytic behaviour of single substituted methoxy- and hydroxybenzoic acids was given at first, data of literature was included. The priority of the investigation was the hydroxylation process induced by OH-radicals. The OH-adduct distribution is generally the same for the hydroxy- as well as for the methoxybenzoic acid isomers. This could be proved by oxidation of these OH-adducts with K 3 Fe(CN) 6 . In the presence of air 68-77 % of the hydroxybenzoic acids are converted into hydroxylation products, whereas with the methoxylated acids this reaction leads only to about 10%. An explanation gives the different decay pathways of the intermediate peroxylradical. The multiple methoxy- and hydroxybenzoic acids show three different reaction possibilities: hydroxylation, replacement of -OCH 3 by -OH and -in case of the cinnamic acids-oxidative decomposition of the rest of the propenic acid under formation of the corresponding benzaldehydes. All these reactions can be expected when irradiating foodstuff, containing these acid compounds. The characteristic formation of these components and their linear dose/concentration relationship make these substrates very promising for the use as markers for irradiation treatment of foodstuff. The second part of this work deals with the gamma-radiation induced chemical changes in mushrooms. The irradiated and non-irradiated samples were freeze-dried and purified from matrix components chromatographically on polyamid columns. In case of the phenolic compounds for 4-hydroxybenzoic acid and three unknown components linear dose/concentration relationships could be obtained. Two of these unknown compounds seem

Hydroxyl-radical induced dechlorination of pentachlorophenol in water

International Nuclear Information System (INIS)

He Yongke; Wu Jilan; Fang Xingwang; Sonntag, C. von

1998-01-01

The hydroxyl-radical induced dechlorination of pentachlorophenol (PCP) in water has been investigated pulse radiolytically. Hydroxyl radicals react with PCP by both electron transfer and addition. The former process results in pentachlorophenoxyl radicals (PCP-O), the latter process followed by rapid HCl elimination gives birth to deprotonated hydroxytetrachlorophenoxyl radicals ( - O-TCP-O). These phenoxyl radicals exhibit maximum absorption around 452 nm, which hinders the proper estimation of the ratio of the two processes. However, these two processes cause different changes in conductivity. In basic solution, the electron transfer causes a conductivity increase due to the formation of OH - whereas an addition followed by HCl elimination results in a conductivity decrease. The concurrence of these two processes reduces the relative variation in conductivity, from which about 53% electron transfer is deduced

Radical-induced oxidation of RAFT agents : a kinetic study

NARCIS (Netherlands)

Li, Changxi; He, Junpo; Zhou, Yanwu; Gu, Yuankai; Yang, Yuliang

2011-01-01

Radical-induced oxidn. of reversible addn.-fragmentation chain transfer (RAFT) agents is studied with respect to the effect of mol. structure on oxidn. rate. The radicals are generated by homolysis of either azobisisobutyronitrile or alkoxyamine and transformed in situ immediately into peroxy

POSSIBLE NATURE OF THE RADIATION-INDUCED SIGNAL IN NAILS: HIGH-FIELD EPR, CONFIRMING CHEMICAL SYNTHESIS, AND QUANTUM CHEMICAL CALCULATIONS

Science.gov (United States)

Tipikin, Dmitriy S.; Swarts, Steven G.; Sidabras, Jason W.; Trompier, François; Swartz, Harold M.

2016-01-01

Exposure of finger- and toe-nails to ionizing radiation generates an Electron Paramagnetic Resonance (EPR) signal whose intensity is dose dependent and stable at room temperature for several days. The dependency of the radiation-induced signal (RIS) on the received dose may be used as the basis for retrospective dosimetry of an individual's fortuitous exposure to ionizing radiation. Two radiation-induced signals, a quasi-stable (RIS2) and stable signal (RIS5), have been identified in nails irradiated up to a dose of 50 Gy. Using X-band EPR, both RIS signals exhibit a singlet line shape with a line width around 1.0 mT and an apparent g-value of 2.0044. In this work, we seek information on the exact chemical nature of the radiation-induced free radicals underlying the signal. This knowledge may provide insights into the reason for the discrepancy in the stabilities of the two RIS signals and help develop strategies for stabilizing the radicals in nails or devising methods for restoring the radicals after decay. In this work an analysis of high field (94 GHz and 240 GHz) EPR spectra of the RIS using quantum chemical calculations, the oxidation–reduction properties and the pH dependence of the signal intensities are used to show that spectroscopic and chemical properties of the RIS are consistent with a semiquinone-type radical underlying the RIS. It has been suggested that semiquinone radicals formed on trace amounts of melanin in nails are the basis for the RIS signals. However, based on the quantum chemical calculations and chemical properties of the RIS, it is likely that the radicals underlying this signal are generated from the radiolysis of L-3,4-dihydroxyphenylalanine (DOPA) amino acids in the keratin proteins. These DOPA amino acids are likely formed from the exogenous oxidation of tyrosine in keratin by the oxygen from the air prior to irradiation. We show that these DOPA amino acids can work as radical traps, capturing the highly reactive and unstable

Role of water and ethanol radicals in the radiation destruction of human deoxyhemoglobin

International Nuclear Information System (INIS)

Szweda-Lewandowska, Z.

1986-01-01

In this study destruction of human deoxyhemoglobin (deoxy-Hb) induced by the action of primary products of water radiolysis and of secondary ethanol radicals was investigated. The extent of destruction was estimated on the basis of absorbance ratio after conversion of hemoglobin into methemoglobin and the changes in the parameters of hemoglobin oxygenation. Deoxy-Hb solutions were irradiated under the atmosphere of argon and N 2 O, in the absence and presence of ethanol. In each case the radiation-chemical yield for hemoglobin destruction was determined. Results were elaborated statistically estimating, by the method of least squares. (orig./PW)

Selectivity of radiation-induced processes in hydrocarbons, related polymers and organized polymer systems

International Nuclear Information System (INIS)

Feldman, V.I.; Sukhov, F.F.; Zezin, A.A.; Orlov, A.Yu.

1999-01-01

Fundamental aspects of the selectivity of radiation-induced events in polymers and polymeric systems were considered: (1) The grounds of selectivity of the primary events were analyzed on the basis of the results of studies of model compounds (molecular aspect). Basic results were obtained for hydrocarbon molecules irradiated in low-temperature matrices. The effects of selective localization of the primary events on the radical formation were examined for several polymers irradiated at low and superlow temperatures (77 and 15 K). A remarkable correlation between the properties of prototype ionized molecules (radical cations) and selectivity of the primary bond rupture in the corresponding polymers were found for polyethylene, polystyrene and some other hydrocarbon polymers. The first direct indication of selective localization of primary events at conformational defects was obtained for oriented high-crystalline polyethylene irradiated at 15 K. The significance of dimeric ring association was proved for the radiation chemistry of polystyrene. Specific mechanisms of low-temperature radiation-induced degradation were also analyzed for polycarbonate and poly(alkylene terephthalates). (2) Specific features of the localization of primary radiation-induced events in microheterogeneous polymeric systems were investigated (microstructural aspect). It was found that the interphase processes played an important role in the radiation chemistry of such systems. The interphase electron migration may result in both positive and negative non-additive effects in the formation of radiolysis products. The effects of component diffusion and chemical reactions on the radiation-induced processes in microheterogeneous polymeric systems were studied with the example of polycarbonate - poly(alkylene terephthalate) blends. (3) The effects of restricted molecular motion on the development of the radiation-chemical processes in polymers were investigated (dynamic aspect). In particular, it

Gastric injury induced by hemorrhage, local ischemia, and oxygen radical generation

International Nuclear Information System (INIS)

Wadhwa, S.S.; Perry, M.A.

1987-01-01

Gastric mucosal injury caused by local intra-arterial generation of oxygen-derived free radicals was compared with gastric injury caused by 30 min of hemorrhage-induced ischemia or local ischemia. The index of injury was the loss of 51 Cr-labeled red cells across the gastric mucosa. Generation of oxygen radicals in the celiac artery caused a rapid increase in mucosal blood loss during the period of radical generation, and this loss was maintained after radical production ceased. Local ischemia produced similar mucosal injury; however, this occurred after reperfusion of the stomach and not during the ischemic episode. Hemorrhage-induced ischemia produced a threefold greater mucosal blood loss than local ischemia. The results of this study indicate that (1) oxygen radicals generated enzymatically in the blood supply to the stomach cause mucosal bleeding of similar magnitude to that observed after local ischemia and (2) that gastric ischemia induced by systemic hypotension produces more severe gastric injury than the same level of local hypotension

Functional properties of nisin–carbohydrate conjugates formed by radiation induced Maillard reaction

International Nuclear Information System (INIS)

Muppalla, Shobita R.; Sonavale, Rahul; Chawla, Surinder P.; Sharma, Arun

2012-01-01

Nisin–carbohydrate conjugates were prepared by irradiating nisin either with glucose or dextran. Increase in browning and formation of intermediate products was observed with a concomitant decrease in free amino and reducing sugar groups indicating occurrence of the Maillard reaction catalyzed by irradiation. Nisin–carbohydrate conjugates showed a broad spectrum antibacterial activity against Gram negative bacteria (Escherichia coli, Pseudomonas fluorescence) as well as Gram positive bacteria (Staphylococcus aureus, Bacillus cereus). Results of antioxidant assays, including that of DPPH radical-scavenging activity and reducing power, showed that the nisin–dextran conjugates possessed better antioxidant potential than nisin–glucose conjugate. These results suggested that it was possible to enhance the functional properties of nisin by preparing radiation induced conjugates suitable for application in food industry. - Highlights: ► Nisin–carbohydrate conjugates were prepared using radiation induced Maillard reaction. ► Conjugation of nisin with dextran/glucose resulted in improvement of antibacterial spectrum. ► Conjugates of nisin with dextran/glucose had significant radical scavenging activity.

Inhibition of lipid peroxidation induced by γ- radiation and AAPH in rat liver and brain mitochondria by mushrooms

International Nuclear Information System (INIS)

Lakshmi, B.; Janardhanan, K.K.; Tilak, J.C.; Devasagayam, T.P.A.; Adhikari, S.

2005-01-01

Exposure to radiation or 2.2' Azobis(2-amidopropane) dihydrochloride (AAPH) induces generation of reactive oxygen species (ROS) especially hydroxyl radical ( . OH) and peroxyl radical (ROO . ), which are capable of inducing lipid peroxidation. Our earlier studies have demonstrated that extracts of the medicinal and edible mushrooms Ganoderma lucidum, Pleurotus florida, Pleurotus sajor-caju and Phellinus rimosus possessed significant antioxidant activity, measured as radical scavenging. In the present study, we examined the protective effect of these mushroom extracts against radiation- and AAPH-induced lipid peroxidation using rat liver and brain mitochondria as model systems. The results obtained showed that the investigated mushroom extracts significantly inhibited the formation of lipid hydroperoxide and thiobarbituric acid reactive substances, indicating membrane protective effects. The finding suggests the profound protective effect of the extracts of the fruiting bodies of G. lucidum, P. florida, P. sajor-caju and P. rimosus against lipid peroxidation by two major forms of ROS capable of inducing this type of damage in a major organelle, the mitochondria from both rat liver and brain. This observation can possibly explain the health benefits of these mushrooms. (author)

Investigations of structure, bonding, and reactions of radiation-induced free radicals in the solid state using electron spin resonance spectroscopy

International Nuclear Information System (INIS)

Hudson, R.L.

1978-01-01

Electron spin resonance spectroscopy (ESR) has been used to study the structure, bonding, and reactions of several types of free radicals produced by γ irradiation of solids at 77K. Well-defined spectral patterns and the use of photolysis and annealing treatments assisted the analyses and interpretations. The radical anion BF 3 - was generated and identified unequivocally in a matrix of tetramethylsilane at 77K. Both the ESR data and theoretical calculations support a pyramidal structure with a bond angle of about 110 0 . The present experiments showed that BF 3 - has ESR parameters consistent with those of the isoelectronic radicals CF 3 , NF 3 + , and F 2 NO. γ irradiation of polycrystalline trimethyl borate at 77K gave an ESR spectrum which was assigned to the dimer radical anion [(MeO) 3 B.B(OMe) 3 ] - . Radical anions of dialkyl carbonates were observed for the first time and found to undergo a β-scission reaction to produce alkyl radicals. This free radical reaction is unusual in that it proceeds both thermally and photochemically. For the dimethyl carbonate radical anion, 13 C parameters were obtained from a 13 C enriched sample. The photolysis of trapped radicals in γ irradiated carboxylic esters, RC(O)OR', was studied by ESR spectroscopy and two different reactions were characterized. Two hypervalent silicon radical anions were prepared and examined in SI(OCH 3 ) 4 . The results of the present work thus represent the first complete sets of data on the silicon 3s and 3p spin densities for such species. The first PL 3 - radical anion was prepared by the γ irradiation of crystalline trimethylphosphite, and identified through its photolysis reactions and from the results of radiation chemical experiments

Radiation-induced changes affecting polyester based polyurethane binder

Science.gov (United States)

Pierpoint, Sujita Basi

The application of thermoplastic polyurethane elastomers as binders in the high energy explosives particularly when used in weapons presents a significantly complex and challenging problem due to the impact of the aging of this polymer on the useful service life of the explosive. In this work, the effects of radiation on the aging of the polyester based polyurethane were investigated using both electron beam and gamma irradiation at various dose rates in the presence and absence of oxygen. It was found by means of GPC that, in the presence and absence of oxygen, the poly (ester urethane) primarily undergoes cross-linking, by means of a carbon-centered secondary alkyl radical. It was also concluded that the polymer partially undergoes scission of the backbone of the main chain at C-O, N-C, and C-C bonds. Substantial changes in the conditions of irradiation and in dose levels did not affect the cross-linking and scission yields. Experiments were also performed with EPR spectroscopy for the purpose of identifying the initial carbon-centered free radicals and for studying the decay mechanisms of these radicals. It was found that the carbon-centered radical which is produced via C-C scission (primary alkyl radical) is rapidly converted to a long-lived allylic species at higher temperatures; more than 80% radicals are converted to allyl species in 2.5 hours. In the presence of oxygen, the allyl radical undergoes a fast reaction to produce a peroxyl radical; this radical decays with a 1.7 hour half-life by pseudo first-order kinetics to negligible levels in 13 hours. FTIR measurements were conducted to identify the radiation-induced changes to the functional groups in the polyester polyurethane. These measurements show an increase in carbonyl, amine and carboxylic groups as a result of reaction of H atoms with R-C-O·, ·NH-R and R-COO·. The FTIR results also demonstrate the production of the unsaturation resulting from hydrogen atom transfer during intrachain conversion

Stimulation of respiration in rat thymocytes induced by ionizing radiation

International Nuclear Information System (INIS)

Gudz, T.I.; Pandelova, I.G.; Novgorodov, S.A.

1994-01-01

The effect of X irradiation on the respiration of rat thymocytes was studied. An increase in the rate of O 2 uptake was observed 1 h after cells were irradiated with doses of 6-10 Gy. The radiation-induced increase in respiration could be blocked by oligomycin, an inhibitor of mitochondrial ATP synthase, suggesting control by increased cytoplasmic ATP turnover. The stimulation of respiration was not associated with changes in the activity of mitochondrial electron transfer enzymes or permeability of the inner membrane. Several inhibitors of processes which used ATP were screened for their effects on the basal respiration rate and on the radiation response. In irradiated thymocytes, an enhancement of inhibition of respiration by ouabain, La 3+ and cycloheximide was observed. These results indicate that the radiation-induced stimulation of respiration is due to changes in ion homeostasis and protein synthesis. The effect of X irradiation was shown to be independent of the redox status of nonprotein thiols and was not associated with detectable changes in some products of lipid peroxidation. The radiation-induced decrease in activity of superoxide dismutase suggests free radical involvement in deleterious effects of radiation. 43 refs., 2 figs., 3 tabs

Effects of tryptophan derivatives and β-carboline alkaloids on radiation- and peroxide-induced transformations of ethanol

International Nuclear Information System (INIS)

Sverdlov, R.L.; Brinkevich, S.D.; Shadyro, O.I.

2014-01-01

The subject of this study was investigation of interactions of tryptophan and its derivatives, including structurally related β-carboline alkaloids with oxygen- and carbon-centered radicals being formed during radiation- and peroxide-induced transformations of ethanol. It was shown that the above named compounds suppressed recombination and disproportionation reactions of α-hydroxyethyl radicals. The inhibitory effects of tryptophan, 5-hydroxytryptophan and serotonin were mainly realized by means of reduction and addition reactions, while those of β-carboline alkaloids – harmine, harmane and harmaline – were due to oxidation reactions. Melatonin displayed low reactivity towards α-hydroxyethyl radicals. Tryptophan derivatives and β-carboline alkaloids were found to inhibit radiation-induced oxidation of ethanol while being virtually not used up. The low transformation yields of tryptophan, 5-hydroxytryptophan and serotonin, as well as β-carboline alkaloids, indicate their capability of regeneration, which could occur on interaction of tryptophan with O ·− 2 and HO · 2 , or on oxidation of α-hydroxyethyl radicals by β-carboline alkaloids. - Highlights: • Tryptophan, 5-hydroxytryptophane and serotonin can reduce or add α-HER. • β-Carboline alkaloids – harmane, harmine, harmaline – can oxidize α-HER. • Tryptophan and its derivatives can reduce oxygen-centered radicals

Radiation-induced inactivation of bovine liver catalase in nitrous oxide-saturated solutions

International Nuclear Information System (INIS)

Gebicka, L.; Metodiewa, D.

1988-01-01

Radiation-induced inactivation of catalase by . OH/H . radicals was studied. It was found that inactivation yield of catalase depended on the dose. Optical spectrum of irradiated catalase showed that no redox processes in active site of enzyme occurred as a result of . OH/H . interaction. (author) 19 refs.; 3 figs

POSSIBLE NATURE OF THE RADIATION-INDUCED SIGNAL IN NAILS: HIGH-FIELD EPR, CONFIRMING CHEMICAL SYNTHESIS, AND QUANTUM CHEMICAL CALCULATIONS.

Science.gov (United States)

Tipikin, Dmitriy S; Swarts, Steven G; Sidabras, Jason W; Trompier, François; Swartz, Harold M

2016-12-01

Exposure of finger- and toe-nails to ionizing radiation generates an Electron Paramagnetic Resonance (EPR) signal whose intensity is dose dependent and stable at room temperature for several days. The dependency of the radiation-induced signal (RIS) on the received dose may be used as the basis for retrospective dosimetry of an individual's fortuitous exposure to ionizing radiation. Two radiation-induced signals, a quasi-stable (RIS2) and stable signal (RIS5), have been identified in nails irradiated up to a dose of 50 Gy. Using X-band EPR, both RIS signals exhibit a singlet line shape with a line width around 1.0 mT and an apparent g-value of 2.0044. In this work, we seek information on the exact chemical nature of the radiation-induced free radicals underlying the signal. This knowledge may provide insights into the reason for the discrepancy in the stabilities of the two RIS signals and help develop strategies for stabilizing the radicals in nails or devising methods for restoring the radicals after decay. In this work an analysis of high field (94 GHz and 240 GHz) EPR spectra of the RIS using quantum chemical calculations, the oxidation-reduction properties and the pH dependence of the signal intensities are used to show that spectroscopic and chemical properties of the RIS are consistent with a semiquinone-type radical underlying the RIS. It has been suggested that semiquinone radicals formed on trace amounts of melanin in nails are the basis for the RIS signals. However, based on the quantum chemical calculations and chemical properties of the RIS, it is likely that the radicals underlying this signal are generated from the radiolysis of L-3,4-dihydroxyphenylalanine (DOPA) amino acids in the keratin proteins. These DOPA amino acids are likely formed from the exogenous oxidation of tyrosine in keratin by the oxygen from the air prior to irradiation. We show that these DOPA amino acids can work as radical traps, capturing the highly reactive and unstable sulfur

Modulation of ionizing radiation induced oxidative imbalance by semi-fractionated extract of Piper betle

Science.gov (United States)

Verma, Savita; Dutta, Ajaswrata; Sankhwar, Sanghmitra; Shukla, Sandeep Kumar

2010-01-01

The study was planned to evaluate modulatory effect of aqueous extract of Piper betle leaf (PBL) on ionizing radiation mediated oxidative stress leading to normal tissues damage during radiotherapy and other radiation exposures. The total polyphenols and flavonoids known as free radical scavenger (chelators) were measured in the extract. To ascertain antioxidant potential of PBL extract, we studied free radical scavenging, metal chelation, reducing power, lipid peroxidation inhibition and ferric reducing antioxidant properties (FRAP ) using in vitro assays. Mice were exposed to varied radiation doses administered with the same extract prior to irradiation to confirm its oxidative stress minimizing efficacy by evaluating ferric reducing ability of plasma, reduced glutathione, lipid peroxidation and micro-nuclei frequency. PBL extract was effective in scavenging DPPH (up to 92% at 100 µg/ml) and superoxide radicals (up to 95% at 80 µg/ml), chelated metal ions (up to 83% at 50 µg/ml) and inhibited lipid peroxidation (up to 45.65% at 500 µg/ml) in a dose dependant manner using in vitro model. Oral administration of PBL extract (225 mg/kg body weight) 1 hr before irradiation in mice significantly enhanced (p < 0.01) radiation abated antioxidant potential of plasma and GSH level in all the observed organs. The treatment with extract effectively lowered the radiation induced lipid peroxidation at 24 hrs in all the selected organs with maximum inhibition in thymus (p < 0.01). After 48 hrs, lipid peroxidation was maximally inhibited in the group treated with the extract. Frequency of radiation induced micronucleated cells declined significantly (34.78%, p < 0.01) at 24 hrs post-irradiation interval by PBL extract administration. The results suggest that PBL extract has high antioxidant potential and relatively non-toxic and thus could be assertively used to mitigate radiotherapy inflicted normal tissues damage and also injuries caused by moderate doses of radiation

Radiation-induced O-glycoside bond scission in carbohydrates

International Nuclear Information System (INIS)

Kisel', R.M.

2005-01-01

Regularities in formation of products resulting from O-glycoside bond cleavage on radiolysis of aqueous solutions of (-methyl-D-glucopyranoside (I), 3-O-methylglucopyranose (II), maltose and lactose were studied. Oxygen and quinones were shown to inhibit radiation-induced homolytic destruction processes taking place in glycosides. The data obtained in this study enabled the authors to demonstrate an important role played by fragmentation reaction of C-2 radicals generated from the starting substances in formation of final radiolysis products. (authors)

Studies on radiation-induced graft polymerization

International Nuclear Information System (INIS)

Omichi, Hideki

1978-09-01

Radiation-induced graft polymerization is used extensively to improve physical properties of polymers, but few processes are now commercialized. The reason for this is partly inadequate basic research on the reaction and partly the difficulty in developing the grafting process with large radiation source. Firstly, new techniques are proposed of studying kinetics of the graft polymerization in heterogeneous system. Based on the grafting yield, the molecular weight of graft chains, and the amount of radicals given by ESR and activation analysis, kinetic parameters are obtained and the reaction mechanism of grafting process is discussed. Secondly, the development of grafting process of poly (vinyl chloride)-butadiene is described. By study of the reaction, process design, construction and operation of the pilot plant, and economic analysis of the process, this process with 60 Co gamma ray sources is shown to be industrially promising. (author)

Synergy between low and high energy radical femtochemistry

International Nuclear Information System (INIS)

Gauduel, Y A

2011-01-01

The deleterious effects of ionizing radiation on integrated biological targets being dependent on the spatio-temporal distribution of short-lived radical processes, a thorough knowledge of these early events requires a real-time probing in the range 10 -15 - 10 -10 s. This manuscript review is focused on the synergy that exists between low (1-10 eV) and high (MeV) energy radiation femtochemistry (LERF, HERF respectively). The synergy remains crucial for the investigation of primary radical processes that take place within the prethermal regime of low energy secondary electrons. The quantum character of very-short lived electron in a prehydrated configuration provides a unique sub-nanometric probe to spatially explore some early radiation-induced biomolecular damage. This approach would foreshadow the development of innovative applications for spatio-temporal radiation biology such as, i) a highly-selective pro-drug activation using well-defined quantum states of short-lived radicals, ii) the real-time nanodosimetry in biologically relevant environments, and iii) the ultrashort irradiation of living cells.

The role of proteins in damage induced by free radicals

International Nuclear Information System (INIS)

Gebicki, J.M.

1996-01-01

The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 μM Cu ++ , and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe ++ . If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage

The role of proteins in damage induced by free radicals

Energy Technology Data Exchange (ETDEWEB)

Gebicki, J.M. [Macquarie Univ., North Ryde, NSW (Australia). School of Biological Sciences

1996-12-31

The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 {mu}M Cu{sup ++}, and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe{sup ++}. If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage.

Effect of dimethyl sulfoxide (DMSO) on radiation-induced heteroallelic reversion in diploid yeast

International Nuclear Information System (INIS)

Singh, D.R.; Mahajan, J.M.; Krishnan, D.

1976-01-01

Dimethyl sulfoxide has cryoprotective and radioprotective properties. It is also an efficient scavenger of radicals produced by radiolysis of water. Gamma-induced reversion of diploid yeast in the presence of this chemical during irradiation have been studied. The dose-modifying factor was in the same range as for survival. When the yeast was irradiated in the frozen state, the observed protection by DMSO disappeared. The results are discussed in terms of direct and indirect actions of radiations and the radical-scavenging ability of this chemical

Radiation inactivation analysis of enzymes. Effect of free radical scavengers on apparent target sizes

International Nuclear Information System (INIS)

Eichler, D.C.; Solomonson, L.P.; Barber, M.J.; McCreery, M.J.; Ness, G.C.

1987-01-01

In most cases the apparent target size obtained by radiation inactivation analysis corresponds to the subunit size or to the size of a multimeric complex. In this report, we examined whether the larger than expected target sizes of some enzymes could be due to secondary effects of free radicals. To test this proposal we carried out radiation inactivation analysis on Escherichia coli DNA polymerase I, Torula yeast glucose-6-phosphate dehydrogenase, Chlorella vulgaris nitrate reductase, and chicken liver sulfite oxidase in the presence and absence of free radical scavengers (benzoic acid and mannitol). In the presence of free radical scavengers, inactivation curves are shifted toward higher radiation doses. Plots of scavenger concentration versus enzyme activity showed that the protective effect of benzoic acid reached a maximum at 25 mM then declined. Mannitol alone had little effect, but appeared to broaden the maximum protective range of benzoic acid relative to concentration. The apparent target size of the polymerase activity of DNA polymerase I in the presence of free radical scavengers was about 40% of that observed in the absence of these agents. This is considerably less than the minimum polypeptide size and may reflect the actual size of the polymerase functional domain. Similar effects, but of lesser magnitude, were observed for glucose-6-phosphate dehydrogenase, nitrate reductase, and sulfite oxidase. These results suggest that secondary damage due to free radicals generated in the local environment as a result of ionizing radiation can influence the apparent target size obtained by this method

A case of likely radiation-induced synchronous esophageal and skin carcinoma following post-operative radiation for breast cancer

International Nuclear Information System (INIS)

Kanogawa, Naoya; Shimada, Hideaki; Kainuma, Osamu; Cho, Akihiro; Yamamoto, Hiroshi; Itami, Makiko; Nagata, Matsuo

2009-01-01

A 71-year-old woman was admitted in January 2008 with on upper thoracic esophageal squamous cell carcinoma and a right chest wall skin tumor. When she was 32 years old, she had a radical mastectomy for right breast cancer and received postoperative radiation. Due to the presence of lung adhesions, trans-thoracic esophagectomy could not be done; thus, a blunt dissection was performed. She was discharged on the 19 th postoperative day. On pathology, a pT2N0M0 (pStage II) esophageal tumor was diagnosed. A resection of her skin tumor underwent 79 days after the esophageal surgery; on pathology, the skin tumor was diagnosed as a basal cell carcinoma. Since the esophageal tumor and the skin tumor occurred in the same area that had received radiation therapy, these tumors were diagnosed as being radiation-induced secondary tumors. In the English language medical literature, several reports of radiation-induced esophageal cancer occurring as a second cancer after radiotherapy for breast cancer have been published. Radiation-induced esophageal cancer rates may increase in Japan given the number of women who previously received radiotherapy for breast cancer. (author)

Reaction mechanism for radiation-induced degradation of poly(methyl methacrylate) as studied by ESR and ESE

International Nuclear Information System (INIS)

Yoshida, H.; Ichikawa, T.

1991-01-01

Reaction mechanism for the radiation-induced degradation of poly(methyl methacrylate) has been studied based on the ESR and electron spin echo observations of the free radicals in the polymer irradiated with γ-rays. It is indicated that the side-chain radical, -CH 2 -CCH 3 (COOC-radicalH 2 )-, is the precursor for the main-chain scission. This radical transforms into the propagating-type radical, a fingerprint of the main-chain scission, without loss of the total radical concentration. UV illumination converts the side-chain radical into the acyl-type radical, -CH 2 -CCH 3 (-C-radical=O)-, which thermally transforms into the propagating-type radical. The radical of the type, -CH 2 -C-radicalCH 3 -CH 2 -, is suggested as a common, immediate precursor for the main-chain scission with and without the UV illumination, though it has not been detected because of its short life-time. (author) 7 refs.; 2 figs

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

International Nuclear Information System (INIS)

Kispeter, J.; Bajusz-Kabok, K.; Fekete, M.; Szabo, G.; Fodor, E.; Pali, T.

2003-01-01

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

The effect of the diazepam to the free radical under the brain radiation injury

International Nuclear Information System (INIS)

Huo Hongmei; Wang Chen; Zhang Zhilin

2007-01-01

Objective: To study the effect of the diazepam on free radical under in the brain radiation injury in the early stage. Methods: A model of whole brain radiation injury in wakefulness was established in the Sprague-Dawley rat. Diazepam was given intraperitoneally 30 minutes before radiation. The brain tissue homogenate was prepared respectively while the rats were executed 6 hours, 1 day, 1 week, 1 month after irradiation. The contents of the superoxide dismutase (SOD) and the malondialdehyde (MDA) in the tissue homogenate were measured by chemical colorimetry. Results: Diazepam could increase the vigor of SOD and reduce the MDA contents after irradiated. Conclusions: Diazepam has certain neuroprotection effect on radiation injury and decreasing the level of the free radicals. (authors)

Visible light- and radiation-induced alkylation of pyridine ring with alkanoic acid

International Nuclear Information System (INIS)

Sugimori, Akira; Yamada, Tetsuo

1986-01-01

Quinoline and 4-methylquinoline are efficiently alkylated with alkanoic acid in the presence of iron(III) sulfate upon visible light-irradiation. Iron(III) sulfate not only accelerates the photoreaction but also increases the yield of alkylation. Gamma-irradiation also brings about the alkylation. In the photo- and radiation-induced alkylation with alkanoic acid, alkyl radicals play important roles. (author)

Micrococcus radiodurans surface exonuclease. Dimer to monomer conversion by ionizing radiation-generated aqueous free radicals

Energy Technology Data Exchange (ETDEWEB)

Mitchel, R E.J.

1980-01-01

Micrococcus radiodurans possesses an exonuclease firmly bound to a middle cell wall membrane layer. Aqueous OH/sup -/ radicals generated chemically or by ionizing radiation cause the immediate release of this enzyme into the surrounding medium. The enzyme is located in a hydrophobic site and can also be released by aqueous n-butanol. When extracted by this solvent it is a non-covalently linked dimer and has a molecular weight of 260,000 as determined by gel filtration. When released by radiation generated OH/sup -/ radicals, the enzyme initially appears in solution as the dimer but is rapidly split by further aqueous radical attack into two 130,000 molecular weight subunits. Hydroxyl radicals are most effective but reducing radicals are also able to monomerize the enzyme. Only the released dimer enzyme is subject to free radical monomerization. Bound dimer enzyme is not split prior to release. No detectable loss of activity or change in catalytic properties accompanies the free radical cleavage of the enzyme. Both subunits of the dimer enzyme possess a tightly bound metal ion (probably Ca/sup 2 +/) required for activity. The monomer but not the dimer enzyme will bind to an anion exchanger. The monomer is susceptible to loss of its metal ion, and consequent inactivation, when exposed to the exchanger in the absence of Ca/sup 2 +/. Besides providing information on some of the immediate non-lethal effects of ionizing radiation, the behavior of this enzyme system demonstrates a potential cellular mechanism by which internally or externally generated free radicals could be utilized by the cell to control various enzymic reactions.

The structure and properties of free radicals: An electron spin resonance study of radiation damage to nucleic acid and protein components and to some sulfur-substituted derivitives

International Nuclear Information System (INIS)

Sagstuen, E.

1979-01-01

When cellular systems are exposed to ionizing radiation the long-term effects may range from minor disturbances to such dramatic changes as mutations and cell death. The processes leading to these macroscopical injuries are primarily confined at the molecular level. In all models aimed at a description of the action of radiation at the molecular level the formation of free radicals (which are species containing unpaired electrons) is a central concept. The technique of ESR spectroscopy is uniquely suited to study free radicals, as it is based on resonance absorption of energy by unpaired electrons in a magnetic field. ESR spectroscopy makes it possible to detect free radicals and, in some cases, to identify them. In order to study free radicals by ESR it is necessary to build up a sufficient number of unpaired spins in the sample (approximately 10 11 or more, depending on the shape of the resonance). This may be different techniques have been used to trap the induced radicals or to attain a sufficient steady state concentration level. A procedure which seems to contain a large amount of information is to irradiate at low temperatures, and, by subsequent heat-treatment of the sample to study the reactions and fate of the induced radicals. In this thesis single crystal studies of aromatic amino acids and pyrimidine derivitives together with some substituted purine derivitives are presented, and the results are discussed in relation to the present knowledge about radical formation in these classes of compounds. Single crystal studies of some sulfur-containing aromatic compounds have been presented with the purpose of shedding light on the electronic structure of sulfur-centred radicals. (JIW)

A novel process for ultrasound-induced radical polymerization in CO2-expanded fluids

NARCIS (Netherlands)

Kemmere, M.F.; Kuijpers, M.W.A.; Prickaerts, R.M.H.; Keurentjes, J.T.F.

2005-01-01

A strong viscosity increase upon polymerization hinders cavitation and subsequent radical formation during an ultrasound-induced bulk polymerization. In this work, ultrasound-induced radical polymerizations of methyl methacrylate (MMA) have been performed in CO2-expanded MMA in order to reduce the

Radical radiation therapy for prostate cancer in Japan. A patterns of care study report

International Nuclear Information System (INIS)

Nakamura, Katsumasa; Mitsuhashi, Norio

2003-01-01

The patterns of radical radiation therapy for prostate cancer are unclear in Japan. A Patterns of Care Study was performed throughout Japan to examine the patterns of radiation therapy for prostate cancer. From 1999 to 2000, extramural audits were performed on 50 randomly selected institutions (∼7% of all institutions in Japan). Detailed information was collected on a total of 311 prostate cancer patients without evidence of distant metastases, who were treated by radiation therapy between 1996 and 1998. Of these 311 patients, 162 treated radically using photon beams were analyzed in this study. Eighty percent of the patients had high-risk diseases defined as T3 or T4 tumors, a pretreatment prostate-specific antigen level >20 ng/ml or poorly differentiated adenocarcinoma. Androgen ablation was performed in 85.8% of patients and the median duration of hormonal therapy before and after radiation therapy was 5.3 and 21.4 months, respectively. The median total dose of radiation therapy to the prostate was 65.0 Gy (range: 20-74 Gy). The 3-year overall and biochemical relapse-free survival rates were 86.7 and 86.1%, respectively. Late toxicity was mild, with only nine patients (5.6%) exhibiting grade 2 late morbidity. The majority of the patients who received radical radiation therapy in Japan have high-risk disease. Androgen ablation plus radiation therapy was commonly used to treat these patients and resulted in high rates of initial control with a low risk of complications. (author)

Effect of radiation sterilization on free radicals content in dry beverages

International Nuclear Information System (INIS)

Hidayati, Nur; Sudiro, Sutjipto; Maha, Munsiah

1998-01-01

This study was done to determine free radicals content in several dry beverages, namely instant coffee, milk powder, cane sugar, nutrisari, tea, and cacao powder after radiation-sterilization at 25 kGy and stored at room (24 o C) and freezing (-13 o C) temperatures. Each sample was vacuum-packed in Al foil laminate pouches, then irradiated at 25 kGy in dry ice temperature. Free radicals contents in some samples after being dissolved or soaked in hot water (73 o C) then freeze-dried were also measured. The free radicals content was measured using Electron Spin Resonance (ESR) Spectroscopy and expressed in spectrum area/g in arbitrary unit. The results showed that free radicals content increased after irradiation, but it decreased immediately after storage especially at room temperature. After about 5 months storage either at room or freezing temperature, free radicals contents of irradiated coffee, milk, powder and cacao powder were similar to those of the unirradiated control, while in tea sample stored at freezing temperature, the free radicals content was still a little bit higher than that stored at room temperature which was already similar to the control. Free radicals content of irradiated sugar as well as nutrisari was higher than the other samples, and the radicals were relatively stable either at room or freezing temperatures. However, after dissolving or soaking the samples in water, the ESR spectra or free radicals contents of the irradiated samples were found to be identical to the control. This indicates that free radicals formed by irradiation in the samples disappear because termination. (authors)

Protection of ionizing radiation-induced cytogenetic damage by hydroalcoholic extract of Cynodon dactylon in Chinese hamster lung fibroblast cells and human peripheral blood lymphocytes.

Science.gov (United States)

Rao, Bola Sadashiva Satish; Upadhya, Dinesh; Adiga, Satish Kumar

2008-01-01

The radiomodulatory potential of hydroalcoholic extract of a medicinal plant Cynodon dactylon (family: Poaceae) against radiation-induced cytogenetic damage was analyzed using Chinese hamster lung fibroblast (V79) cells and human peripheral blood lymphocytes (HPBLs) growing in vitro. Induction of micronuclei was used as an index of cytogenetic damage, evaluated in cytokinesis blocked binucleate cells. The hydroalcoholic Cynodon dactylon extract (CDE) rendered protection against the radiation-induced DNA damage, as evidenced by the significant (p<0.001) reduction in micronucleated binucleate cells (MNBNC%) after various doses of CDE treatment in V79 cells and HPBLs. The optimum dose of CDE (40 and 50 microg/ml in HPBLs and V79 cells, respectively) with the greatest reduction in micronuclei was further used in combination with various doses of gamma radiation (0.5, 1, 2, 3, and 4 Gy) exposed 1 h after CDE treatment. A linear dose-dependent MNBNC% increase in radiation alone group was observed, while 40/50 microg/ml CDE significantly resulted in the reduction of MNBNC%, compared to the respective radiation alone groups. CDE resulted in a dose-dependent increase in free radical scavenging ability against various free radicals, viz., 2, 2-diphenyl-2-picryl-hydrazyl (DPPH); 2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS); superoxide anion (O2*-); hydroxyl radical (OH*) and nitric oxide radical (NO*) generated in vitro. Also, an excellent (70%) inhibition of lipid peroxidation in vitro was observed at a dose of 300 microg/ml CDE, attaining the saturation point at higher doses. The present findings demonstrated the radioprotective effect of CDE, also rendering protection against radiation-induced genomic instability and DNA damage. The observed radioprotective effect may be partly attributed to the free radical scavenging and antilipid peroxidative potential of CDE.

Differential modification of oxic and anoxic radiation damage by chemicals. I. Simulation of the action of caffeine by certain inorganic radical scavengers

International Nuclear Information System (INIS)

Kesavan, P.C.; Sharma, G.J.; Afzal, S.M.J.

1978-01-01

Caffeine affords partial radioprotection against oxic damage, but potentiates anoxic damage in dry as well as presoaked barley seeds. Since our earlier studies have implicated a physicochemical pathway of action for such differential modification by caffeine, the effect of inorganic substances, known to scavenge specific categories of free radicals, on the oxic and anoxic components of radiation damage was investigated. It is found that the radiation-induced oxic damage is significantly reduced by potassium permanganate, potassium iodide, potassium nitrate, and potassium ferrocyanide which scavenge predominantly .H + e - /sub aq/, .OH, e - /sub aq/, and .OH radicals, respectively. Each of these four substances, like caffeine, also potentiates anoxic damage in dry seeds, but the anoxic damage in presoaked seeds is potentiated only by potassium ferrocyanide. These results do not confirm the view in the literature that the anoxic sensitization is largely mediated by .OH radicals. A discussion of these observations and the validity of comparing our seed data with those derived from experiments with bacterial spores and ''naked'' DNA solutions is presented

Protection from ionizing radiation induced damages by phytoceuticals and nutraceuticals

International Nuclear Information System (INIS)

Nair, C.K.K.

2012-01-01

Exposure of living systems to ionizing radiation cause a variety of damages to DNA and membranes due to generation of free radicals and reactive oxygen species. The radiation induced lesions in the cellular DNA are mainly strand breaks, damage to sugar moiety, alterations and elimination of bases, cross links of the intra and inter strand type and cross links to proteins while peroxidation of the lipids and oxidation of proteins constitute the major lesions in the membranes. The radioprotectors elicit their action by various mechanisms such as i) by suppressing the formation of reactive species, ii) detoxification of radiation induced species, iii) target stabilization and iv) enhancing the repair and recovery processes. The radioprotective compounds are of importance in medical, industrial, environmental, military and space science applications. Radiation protection might offer a tactical advantage on the battlefield in the event of a nuclear warfare. Radioprotectors might reduce the cancer risk to populations exposed to radiations directly or indirectly through industrial and military applications. The antioxidant and radioprotective properties a few of these agents under in vitro and in vivo conditions in animal models will be discussed

Electron spin resonance study on γ-ray-induced radical species in ethylene hydrate

International Nuclear Information System (INIS)

Takeya, Kei; Sugahara, Takeshi; Ohgaki, Kazunari; Tani, Atsushi

2007-01-01

Electron spin resonance (ESR) study on γ-irradiated synthetic ethylene hydrate was performed to investigate induced radicals and their thermal stability. ESR spectra of induced 3-butenyl radical (.CH 2 C 2 H 3 =CH 2 ,g=2.0039±0.0005,A α =2.2±0.1mTandA β =3.0±0.1mT) and induced ethyl radical (.C 2 H 5 , g=2.0044±0.0005, A α =2.2±0.1mT and A β =2.7±0.1mT) were observed in irradiated ethylene hydrate. The decay of the 3-butenyl radicals was observed above 200 K with the activation energy of 51.9±4.4kJ/mol. The obvious decay of ethyl radicals starts above 240 K that is close to the dissociation temperature of ethylene hydrate at atmospheric pressure. The activation energy of the ethyl radical decay is estimated as 63.4±8.2kJ/mol and nearly equal to the enthalpy change of ethylene hydrate into liquid water and gaseous ethylene. It is suggested that the decay of ethyl radicals would be caused by the hydrate dissociation and that ethylene hydrate dissociates into water (supercooled) and ethylene at 240-265 K.

Modification of DNA bases in mammalian chromatin by radiation-generated free radicals

International Nuclear Information System (INIS)

Gajewski, E.; Rao, G.; Nackerdien, Z.; Dizdaroglu, M.

1990-01-01

Modification of DNA bases in mammalian chromatin in aqueous suspension by ionizing radiation generated free radicals was investigated. Argon, air, N2O, and N2O/O2 were used for saturation of the aqueous system in order to provide different radical environments. Radiation doses ranging from 20 to 200 Gy (J.kg-1) were used. Thirteen products resulting from radical interactions with pyrimidines and purines in chromatin were identified and quantitated by using the technique of gas chromatography/mass spectrometry with selected-ion monitoring after acidic hydrolysis and trimethylsilylation of chromatin. The methodology used permitted analysis of the modified bases directly in chromatin without the necessity of isolation of DNA from chromatin first. The results indicate that the radical environment provided by the presence of different gases in the system had a substantial effect on the types of products and their quantities. Some products were produced only in the presence of oxygen, whereas other products were detected only in the absence of oxygen. Products produced under all four gaseous conditions were also observed. Generally, the presence of oxygen in the system increased the yields of the products with the exception of formamidopyrimidines. Superoxide radical formed in the presence of air, and to a lesser extent in the presence of N2O/O2, had no effect on product formation. The presence of oxygen dramatically increased the yields of 8-hydroxypurines, whereas the yields of formamidopyrimidines were not affected by oxygen, although these products result from respective oxidation and reduction of the same hydroxyl-adduct radicals of purines. The yields of the products were much lower than those observed previously with DNA

Mechanisms of radiation-induced normal tissue toxicity and implications for future clinical trials

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae Ho; Jenrow, Kenneth A.; Brown, Stephen L. [Dept.of Radiation Oncology, Henry Ford Health System, Detroit (United States)

2014-09-15

To summarize current knowledge regarding mechanisms of radiation-induced normal tissue injury and medical countermeasures available to reduce its severity. Advances in radiation delivery using megavoltage and intensity-modulated radiation therapy have permitted delivery of higher doses of radiation to well-defined tumor target tissues. Injury to critical normal tissues and organs, however, poses substantial risks in the curative treatment of cancers, especially when radiation is administered in combination with chemotherapy. The principal pathogenesis is initiated by depletion of tissue stem cells and progenitor cells and damage to vascular endothelial microvessels. Emerging concepts of radiation-induced normal tissue toxicity suggest that the recovery and repopulation of stromal stem cells remain chronically impaired by long-lived free radicals, reactive oxygen species, and pro-inflammatory cytokines/chemokines resulting in progressive damage after radiation exposure. Better understanding the mechanisms mediating interactions among excessive generation of reactive oxygen species, production of pro-inflammatory cytokines and activated macrophages, and role of bone marrow-derived progenitor and stem cells may provide novel insight on the pathogenesis of radiation-induced injury of tissues. Further understanding the molecular signaling pathways of cytokines and chemokines would reveal novel targets for protecting or mitigating radiation injury of tissues and organs.

Mechanisms of radiation-induced normal tissue toxicity and implications for future clinical trials

International Nuclear Information System (INIS)

Kim, Jae Ho; Jenrow, Kenneth A.; Brown, Stephen L.

2014-01-01

To summarize current knowledge regarding mechanisms of radiation-induced normal tissue injury and medical countermeasures available to reduce its severity. Advances in radiation delivery using megavoltage and intensity-modulated radiation therapy have permitted delivery of higher doses of radiation to well-defined tumor target tissues. Injury to critical normal tissues and organs, however, poses substantial risks in the curative treatment of cancers, especially when radiation is administered in combination with chemotherapy. The principal pathogenesis is initiated by depletion of tissue stem cells and progenitor cells and damage to vascular endothelial microvessels. Emerging concepts of radiation-induced normal tissue toxicity suggest that the recovery and repopulation of stromal stem cells remain chronically impaired by long-lived free radicals, reactive oxygen species, and pro-inflammatory cytokines/chemokines resulting in progressive damage after radiation exposure. Better understanding the mechanisms mediating interactions among excessive generation of reactive oxygen species, production of pro-inflammatory cytokines and activated macrophages, and role of bone marrow-derived progenitor and stem cells may provide novel insight on the pathogenesis of radiation-induced injury of tissues. Further understanding the molecular signaling pathways of cytokines and chemokines would reveal novel targets for protecting or mitigating radiation injury of tissues and organs.

γ-radiation induced corrosion of copper in bentonite-water systems under anaerobic conditions

Science.gov (United States)

Karin Norrfors, K.; Björkbacka, Åsa; Kessler, Amanda; Wold, Susanna; Jonsson, Mats

2018-03-01

In this work we have experimentally studied the impact of bentonite clay on the process of radiation-induced copper corrosion in anoxic water. The motivation for this is to further develop our understanding of radiation-driven processes occurring in deep geological repositories for spent nuclear fuel where copper canisters containing the spent nuclear fuel will be embedded in compacted bentonite. Experiments on radiation-induced corrosion in the presence and absence of bentonite were performed along with experiments elucidating the impact irradiation on the Cu2+ adsorption capacity of bentonite. The experiments presented in this work show that the presence of bentonite clay has no or very little effect on the magnitude of radiation-induced corrosion of copper in anoxic aqueous systems. The absence of a protective effect similar to that observed for radiation-induced dissolution of UO2 is attributed to differences in the corrosion mechanism. This provides further support for the previously proposed mechanism where the hydroxyl radical is the key radiolytic oxidant responsible for the corrosion of copper. The radiation effect on the bentonite sorption capacity of Cu2+ (reduced capacity) is in line with what has previously been reported for other cations. The reduced cation sorption capacity is partly attributed to a loss of Al-OH sites upon irradiation.

Radiation-chemical discussion on inverse dose-rate effect observed in radiation-induced strand breaks of plasmid DNA

International Nuclear Information System (INIS)

Masuda, Takahiro

1994-01-01

Experimental results of inverse dose-rate effect, so-called Kada Effects, which was published by Takakura and her coworkers on radiation-induced strand breaks of plasmid DNA in aerated aqueous solution, have been kinetically analyzed and discussed on the basis of radiation chemistry. the kinetic analysis indicates that there are two possible mechanisms; 1) equilibrium mixture of O 2 - and HO 2 is responsible for strand breaks of DNA, and 2) peroxyl radical produced from citrate is effective for the strand breaks. However, the detailed kinetic analysis revealed that the latter is improbable because unimolecular decay of the peroxyl radical must be assumed to be negligible for its participation despite fast decay of analogous organic peroxyl radicals. The analysis has also given 9.93±0.10 dm 3 mol -1 s -1 per nucleotide unit, which corresponds to 7.62 x 10 4 dm 3 mol -1 s -1 per DNA molecule, as the rate constant for the reaction of the equilibrium mixture with plasmid pBR 322 DNA. Furthermore the probability that the reaction of the mixture with a nucleotide unit of DNA leads to strand breaks was obtained to be 3.36 x 10 -3 for gamma-irradiated system and 1.98 x 10 -3 for beta-irradiated system, respectively. (author)

Radiation induced sulfur dioxide removal

International Nuclear Information System (INIS)

Chmielewski, A.G.

2000-01-01

The biggest source of air pollution is the combustion of fossil fuels, were pollutants such as particulate, sulfur dioxide (SO 2 ), nitrogen oxides (NO x ), and volatile organic compounds (VOC) are emitted. Among these pollutants, sulfur dioxide plays the main role in acidification of the environment. The mechanism of sulfur dioxide transformation in the environment is partly photochemical. This is not direct photooxidation, however, but oxidation through formed radicals. Heterogenic reactions play an important role in this transformation as well; therefore, observations from environmental chemistry can be used in air pollution control engineering. One of the most promising technologies for desulfurization of the flue gases (and simultaneous denitrification) is radiation technology with an electron accelerator application. Contrary to the nitrogen oxides (NO x ) removal processes, which is based on pure radiation induced reactions, sulfur dioxide removal depends on two pathways: a thermochemical reaction in the presence of ammonia/water vapor and a radiation set of radiochemical reactions. The mechanism of these reactions and the consequent technological parameters of the process are discussed in this paper. The industrial application of this radiation technology is being implemented in an industrial pilot plant operated by INCT at EPS Kaweczyn. A full-scale industrial plant is currently in operation in China, and two others are under development in Japan and Poland. (author)

Radiation-induced damage in E. coli B: The effect of superoxide radicals and molecular oxygen. Progress report, December 1, 1978--November 30, 1979

International Nuclear Information System (INIS)

Samuni, A.; Czapski, G.

The roles of superoxide radicals and of molecular oxygen in the radiodamage of E. coli B suspended in dilute phosphate buffer were studied. The presence of high concentrations of polyethylene glycol in the γ-irradiated cell suspensions, had no effect on bacterial radiosensitivity. This indicates that the damage was primarily endogenous, i.e. originated intracellularly. Saturation of the cell suspensions with N 2 O doubled the radiosensitivity, thus indicating that OH radicals are responsible for the majority of the damage (indirect radiation effect). The presence of oxygen either in the absence or presence of N 2 O brought about roughly a three-fold increase in the radiosensitivity. Since in the presence of N 2 O all e - /sub aq/ are scavenged by the nitrous oxide rather than by oxygen, this shows that superoxide radicals play no role in the bacterial radiodamage. Our results substantiate the attribution of the oxygen effect to a direct interaction of O 2 with the hydroxyl-radical-damaged sites on vital biomolecules, and exclude any significant contribution of e - /sub aq/ and superoxide radicals to the cellular radiodamage

Model studies of radiation induced oxidation and reduction processes in DNA

International Nuclear Information System (INIS)

Hole, E.O.

1992-01-01

The papers presented in this thesis represent the major part of a systematic study of primary and secondary radiation induced damages in DNA. The magnetic resonance techniques EPR, ENDOR and FSE have been the experimental methods used. The study of radical formation in isolated DNA components under different environmental conditions demonstrates certain characteristics of the DNA components which are important in the study of DNA. It has been clearly demonstrated that the electrostatic environment, in particular the hydrogen bond pattern, is a vital factor for the secondary reaction scheme. Even radicals which are found in all related systems seem to be formed by different reaction pathways, depending upon the specific matrix. 92 refs., 2 figs., 6 tabs

Radioprotective effect of methanolic root extract of Loeseneriella arnottiana on radiation induced DNA damage in human lymphocytes in vitro

International Nuclear Information System (INIS)

Prajna, P.S.

2012-01-01

Intense exposure to ionization radiation by accidental, occupational or therapeutical purpose causes cellular damage mainly by formation of excessive reactive oxygen species (ROS) or by free radicals. Humans are intentionally exposed to ionising radiation for diagnostic or therapeutic purposes. The use of ionising radiation in cancer therapy may lead to transient and/or permanent injury to normal tissues within the treatment field. To increase the therapeutic index of radiation therapy, various modes of radioprotection have been developed that selectively reduce cytotoxic effects to normal tissues. Because radiation-induced cellular damage is attributed primarily to the harmful effects of free radicals, molecules with radical scavenging properties are particularly promising as radioprotectors. Loeseneriella arnottiana, a member of family Hippocrateaceae, is a climbing shrub used by traditional medicine practitioners. To study the antioxidant activity and radioprotective effect of methanolic root extract of Loeseneriella arnottiana against electron beam radiation induced DNA damage in human lymphocytes. Loeseneriella arnottiana roots were dried and extracted using methanol by solvent extraction method. Antioxidant activity was measured by DPPH method. DNA damage was assessed by comet assay parameters. The lymphocytes were incubated for one hour with two different concentrations 10 μg and 50 μg of root extract before exposure to 2 Gy electron beam radiation. 30 μg of methanolic root extract of Loeseneriella arnottiana exhibited 96% radical scavenging activity comparable to 15 μg of ascorbic acid. In reducing power assay it showed dose dependent increase in absorbance indicating that extract is capable of donating hydrogen atoms. Pretreatment of lymphocytes with 10 μg and 50 μg of root extract before irradiation resulted in reduction in the Comet length, Olive tail moment, percentage of DNA in tail when compared to the radiation control group. Results of this

Adenocarcinoma of the rectum treated by radical external radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Catton, Charles N; Brierley, James D; Cummings, Bernard J; Wong, C Shun; Keane, Thomas J; O' Sullivan, Brian; Goodman, Phyllis

1995-01-15

Purpose: To assess the long-term survival and response rates of patients with primary rectal cancer to radical radiation therapy. Methods and Materials: Between 1978 and 1987, 229 patients were treated at the Princess Margaret Hospital with radical external radiation therapy for adenocarcinoma of the rectum. Patients were treated with radiation either because they were considered to have unresectable tumors, were medically unfit, or refused surgery, or for a combination of these factors. Doses ranged from 40 Gy in 10 fractions by a split course over 6 weeks to 60 Gy in 30 fractions in 6 weeks. The most commonly prescribed treatment was 52 Gy target absorbed dose in 20 daily fractions over 4 weeks. Results: The overall 5-year actuarial survival rate was 27%; for patients with mobile tumors, it was 48%, partially fixed 27%, and fixed tumor 4%. Forty-eight of the 97 patients (50%) with mobile tumors, 11 of the 37 patients (30%) with partially fixed tumors, and 7 of the 77 patients (9%) with fixed tumors had clinically complete tumor regression following radiation. Of these, 18 of the mobile, 6 of the partially fixed, and 5 of the fixed tumors later relapsed locally. Fifty patients had salvage surgery after failing to achieve complete remission or for local relapse, with a 5-year actuarial survival rate of 42% from the time of surgery. Conclusion: Although radiation therapy can cure some patients with mobile or partially fixed rectal adenocarcinomas who refuse or are unsuitable for surgery, local control remains a problem; salvage surgery should be considered in patients who relapse or fail to go into complete remission and who are fit to undergo surgery. For patients with fixed rectal cancers, high-dose external-beam radiation should be part of a planned preoperative regimen or be palliative in intent.

Generation of radicals in hard biological tissues under the action of laser radiation

Science.gov (United States)

Sviridov, Alexander P.; Bagratashvili, Victor N.; Sobol, Emil N.; Omelchenko, Alexander I.; Lunina, Elena V.; Zhitnev, Yurii N.; Markaryan, Galina L.; Lunin, Valerii V.

2002-07-01

The formation of radicals upon UV and IR laser irradiation of some biological tissues and their components was studied by the EPR technique. The radical decay kinetics in body tissue specimens after their irradiation with UV light were described by various models. By the spin trapping technique, it was shown that radicals were not produced during IR laser irradiation of cartilaginous tissue. A change in optical absorption spectra and the dynamics of optical density of cartilaginous tissue, fish scale, and a collagen film under exposure to laser radiation in an air, oxygen, and nitrogen atmosphere was studied.

ESR low-temperature investigations on water-containing biological substances to determine type, concentration and kinetics of the free radicals induced by irradiation with X-rays and β-radiation

International Nuclear Information System (INIS)

Fell, H.A.

1975-01-01

In the present work, ESR investigations on pure water and further biological interesting substances with high water content were carried out. In order to stabilize the free primary radicals occurring after irradiation, it was necessary to cool down the samples to the temperature of liquid helium. Methods were developed which enabled irradiation of the pure sample substance at this temperature to be performed. Two different kinds of radiation were applied, X-ray and β-radiation, and the results were compared with one another. The problem of transporting the irradiated sample from the place of irradiation to the measuring position maintaining 4.2 K was solved. A device was constructed to study the radical kinetics with whose assistance the samples can be brought to a pre-chosen temperature for a certain time. A calibration of the ESR spectrometer as well as the use of a secondary standard was necessary for the quantitative determination of the radical concentration. The type and concentration of the primary radicals occurring were investigated in the measured samples as well as the reduction of the radical concentration with increasing temperature determined. The measured values were compared with theoretical considerations. The effect of the radicals on biological systems at various temperatures was discussed. (orig./LH) [de

Antigenotoxic potential of Asparagus racemosus root extract against electron beam radiation induced micronuclei formation in Swiss albino mice

International Nuclear Information System (INIS)

Bhandary, B. Satheesh Kumar; Sharmila, K.P.; Suchetha Kumari, N.; Bhat, Vadish S.; Shetty, Jayaram; Peter, Alex John; Jose, Jerish M.; Fernandes, Ronald

2016-01-01

To evaluate the antigenotoxic potential of Asparagus Racemosus Root ethanolic extract (ARE) against electron beam radiation induced micronuclei formation in Swiss albino mice. Micronucleus assay was performed in the bone marrow of Swiss albino mice according to the method of Hosseinimehr et al., 2003. The experimental animals were orally administered 200 mg/kg body weight of ARE once daily for 15 consecutive days. At the end of experimental period, the animals were euthanized and the bone marrow was collected from the femur. Control (C), Radiation control (RC) and drug control (DC) group was also maintained. The number of radiation induced Micronucleated Polychromatic Erythrocytes (MnPCE) and Micronucleated Normochromatic Erythrocytes were decreased in the ARE treated mice which was statistically significant (p<0.05) compared to radiation control group. Present findings demonstrate the antigenotoxic potential of ARE against electron beam radiation induced micronuclei formation which may be attributed to scavenging of radiation-induced free radicals

Effect of shear stress and free radicals induced by ultrasound on erythrocytes

International Nuclear Information System (INIS)

Kondo, T.; Fukushima, Y.; Kon, H.; Riesz, P.

1989-01-01

The present study was undertaken to elucidate the mechanism of hemolysis induced by ultrasound. Ar or N2O gas was used to distinguish between cavitation with or without free radical formation (hydroxyl radicals and hydrogen atoms). Free radical formation was examined by the method of spin trapping combined with ESR. After sonication of erythrocyte suspensions, several structural and functional parameters of the erythrocyte membrane--hemolysis, membrane fluidity, membrane permeability, and membrane deformability--were examined. Although free radical formation was observed in the erythrocyte suspensions sonicated in the presence of Ar, no free radical formation was observed in the presence of N2O. However, the hemolysis behavior induced by ultrasound was similar in the presence of Ar or N2O. The membrane fluidity, permeability, and deformability of the remaining unlysed erythrocytes after sonication in the presence of Ar or N2O were unchanged and identical to those of the control cells. On the other hand, after gamma irradiation (700 Gy), the hemolysis behavior was quite different from that after sonication, and the membrane properties were significantly changed. These results suggest that hemolysis induced by sonication was due to mechanical shearing stress arising from cavitation, and that the membrane integrity of the remaining erythrocytes after sonication was the same as that of control cells without sonication. The triatomic gas, N2O, may be useful for ultrasonically disrupting cells without accompanying free radical formation

Effect of HALS on radiation discoloration of PE

International Nuclear Information System (INIS)

Wang Huiliang; Wang Chun; Chen Wenxiu

2001-01-01

The effects of hindered amine light stabilizers (HALS) on the radiation-induced discoloration of polyethylene (PE) are studied by measuring the yellowness index (YI) of PE. It is found that all the HALS used are effective in preventing PE from radiation-induced discoloration. The YI of PE added pentamethyl HALS (PMPM, PPMPM) is a little higher than that of PE added corresponding tetramethyl HALS (TMPM, PTMPM) when radiation dose is low than 100 kGy, but when the radiation dose is higher than 100 kGy, the YI of PE added pentamethyl HALS is lower. Pentamethyl HALS is more effective in preventing PE from radiation-induced discoloration when radiation dose is higher. It is also found that polymeric HALS is more effective in preventing PE from radiation-induced discoloration than corresponding monomeric HALS when radiation dose is higher than 200 kGy. The formation of alkyl free radical, carbonyl after irradiation is measured. It is found that the relative concentration of free radical formed in PE added TMPM is higher than that of PE added PMPM when radiation dose is relatively high. The carbonyl index of PE containing pentamethyl HALS is less than that of PE containing tetramethyl HALS when radiation is relatively low, but the results is contrary when radiation dose is relatively high. It is believed that HALS prevents PE from radiation-induced discoloration by scavenging free radicals formed in irradiated PE

Functionalization of Polymer Surfaces by Radiation-Induced Grafting for Separation of Heavy Metal Ions

Energy Technology Data Exchange (ETDEWEB)

Przybytniak, G; Kornacka, E M; Fuks, L; Walo, M; Lyczko, K; Mirkowski, K [Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland)

2012-09-15

The reported investigations were focused on the elucidation of the most important factors influencing radiation-induced grafting; particularly (1) the effect of radical population generated in polymeric matrix on degree of grafting, (2) parameters determined grafting and its procedure, (3) correlation between layer structure formed via copolymerization and content of monomers in the initial solution. Sorption capacity of the adsorbants was evaluated using {sup 152}Eu{sup 3+} as a marker monitoring depletion of the radioisotope from the initial solution by gamma radiometer. Electron spin resonance spectroscopy (EPR) and gas chromatography (GC) studies confirmed that yield of radiation-induced radicals increases in the following order polystyrene (PS) < polypropylene (PP) < polyethylene (PE). The same relationship was found for efficiency of radiation grafting. It was concluded that under comparable conditions the content of radicals in polymeric matrices determines grafting degree. It was found that application of the simultaneous method of grafting introduces to the grafted layers crosslinking or/and branching as well as degradation of functional groups. All these phenomena reduce access of Eu{sup 3+} to the studied sorbent therefore sorption capacity of the polyamide functionalized via pre-irradiation (indirect) method is higher than that determined for the sorbent prepared by simultaneous method of grafting. When two monomers, acrylic acid (AAc) and acrylamide (AAm) , contributed in the formation of grafted layer, their input into copolymerization was not proportional to the concentrations in the feed solution. It was confirmed that grafting of the monomers shows synergetic effect as the yield of copolymerization exceeds degree of grafting achieved for individual components. (author)

Protective effects of Punica Granatum (L) and synthetic ellagic acid on radiation induced biochemical alterations in Swiss albino mice

International Nuclear Information System (INIS)

Sharmila, K.P.; Satheesh Kumar Bhandary, B.; Suchetha Kumari, N.; Vadisha Bhat, S.; Sherly, Sharmila; Sanjeev, Ganesh

2013-01-01

Ionizing radiations produce deleterious effects in the living organisms and the rapid technological advancement has increased human exposure to ionizing radiations enormously. Radiotherapy, which is a chief modality to treat cancer, faces a major drawback because it produces severe side effects developed due to damage to normal tissue by reactive oxygen species (ROS). Recent studies have indicated that some commonly used medicinal plants may be good sources of potent but non-toxic radioprotectors. The pomegranate, Punica granatum L., an ancient, mystical, and highly distinctive fruit, is the predominant member of the Punicaceae family. It is used in several systems of medicine for a variety of ailments. The objective of the present study was to investigate the protective effects of ethanolic extracts of pomegranate whole fruit (EPWF) and seeds (EPS) and Synthetic Ellagic acid (EA) against Electron beam radiation(EBR) induced biochemical alterations in Swiss albino mice. The extracts and synthetic compound were assessed for its radical scavenging property by DPPH radical scavenging and Ferric Reducing Antioxidant Power assays. The animals were exposed to sub-lethal dose (6 Gy) of Electron Beam Radiation and then treated with 200 mg/kg body wt. of pomegranate extracts and synthetic ellagic acid for 15 consecutive days. The biochemical estimations were carried out in the liver homogenate of the sacrificed animals. Radiation induced depletion in the level of reduced glutathione and total antioxidant capacity were prevented significantly by EPWF, EPS and EA administration. Also there was significant reduction in the levels of membrane lipid peroxidation in the treated groups compared to irradiated control. The findings of our study indicate the protective efficacy of pomegranate extracts and synthetic ellagic acid on radiation induced biochemical changes in mice may be due to its free radical scavenging and increased antioxidant levels. (author)

Kinetics of radiation-induced structural alterations in electron-irradiated polymer-based composites

International Nuclear Information System (INIS)

Zaikin, Yu.A.; Potanin, A.S.; Koztaeva, U.P.

2002-01-01

Complete text of publication follows. In our previous studies measurements of internal friction temperature dependence were used for characterization of thermally activated and radiation-induced structural evolution in different types of polymer-based composites. This paper supplements these measurements with kinetic studies of internal friction (IF) parameters and EPR signals in a glass-cloth epoxy-filled laminate ST-ETF after electron irradiation up to doses of 1-10 MGy. Experiment have shown that the lifetime of free radicals in this composite considerably exceeds the characteristic time of molecular structural rearrangement due to scission and cross-linking after irradiation, as determined from IF measurements. This result is explained by slow proceeding of sterically hindered disproportionation reactions that stabilize the end groups of the macro-chain disrupt during irradiation and finally fix the act of scission. A mathematical model is formulated for description of structural evolution and alterations of IF parameters in polymer-based composites during and after electron irradiation. The description is based on the track model of radiation damage in polymers and phenomenological theory of radiation-induced structural transformations. General description does not give details of radiation-chemical conversion in different structural components of composites but indicates the direction of their structural evolution. In the model considered a composite material was divided into three parts (binder, filler, and a boundary layer). It was supposed that after primary distribution of radiation energy radiation-chemical conversion proceeds independently in each of these regions. It was also suggested that all the radical reactions were of the second order. On the example of glass-cloth laminate ST-ETF it is shown that this model allows to describe alterations in composite structural characteristics during irradiation and in the course of their self-organization after

Radiation-induced electron migration in nucleic acids

International Nuclear Information System (INIS)

Fuciarelli, A.F.; Sisk, E.C.; Miller, J.H.; Zimbrick, J.D.

1994-01-01

Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to non-random types of damage along DNA manifested distal to the sites of the initial energy deposition. Radiation-induced electron migration in nucleic acids has been examined using oligonucleotides containing 5-bromouracil (5-BrU). Interaction of 5-BrU with solvated electrons results in release of bromide ions and formation of uracil-5-yl radicals. Monitoring either bromide ion release or uracil formation provides an opportunity to study electron migration processes in model nucleic acid systems. Using this approach we have discovered that electron migration along oligonucleotides is significantly influenced by the base sequence and strandedness. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution, which compares with mean migration distances of 6-10 bp for Escherichia coli DNA irradiated in solution and 5.5 bp for E. coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5' to 3' direction along a double-stranded oligonucleotide containing a region of purine bases adjacent to the 5-BrU moiety. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation. (Author)

Radiation induced emulsion polymerization

International Nuclear Information System (INIS)

Stannett, V.T.; Stahel, E.P.

1990-01-01

High energy radiation is particularly favored for the initiation of emulsion polymerization. The yield of free radicals, for example, from the radiolysis of the aqueous phase, is high; G(radical) values of 5-7. In addition, the rather special kinetics associated with emulsion polymerization lead, in general, to very large kinetic chain lengths, even with 'non-ideal' monomers such as vinyl acetate. Together, high polymerization rates at low doses become possible. There are some important advantages of radiation polymerization compared with chemical initiators, such as potassium persulfate. Perhaps the most important among them is the temperature independence of the initiation step. This makes low temperature polymerization very accessible. With monomers such as vinyl acetate, where chain termination to monomer is predominant, low temperatures lead to often highly desirable higher molecular weights. With styrene, the classical ideally behaved monomer, there are the advantages such as, for example, the feasibility of using cationic monomers. These and some attendant disadvantages are discussed in detail, including pilot plant studies

Amelioration of radiation induced DNA damage and biochemical alterations by Punica Granatum (L) extracts and synthetic ellagic acid in Swiss albino mice

International Nuclear Information System (INIS)

Satheesh Kumar Bhandary, B.; Sharmila, K.P.; Suchetha Kumari, N.; Vadisha Bhat, S.; Sherly, Sharmila; Sanjeev, Ganesh

2013-01-01

Radiation therapy has been used in cancer treatment for many decades; Although effective in killing tumor cells, ROS produced in radiotherapy threaten the integrity and survival of surrounding normal cells. ROS are scavenged by radioprotectors before they can interact with biochemical molecules, thus reducing harmful effects of radiation. The pomegranate, Punica granatum L., an ancient, mystical, and highly distinctive fruit, is the predominant member of the Punicaceae family. It is used in several systems of medicine for a variety of ailments. The objective of the present study was to investigate the protective effects of ethanolic extracts of pomegranate whole fruit (EPWF) and seeds (EPS) and Synthetic Ellagic acid (EA) against Electron Beam Radiation (EBR) induced DNA damage and biochemical alterations in Swiss Albino mice. The extracts and synthetic compound were assessed for its radical scavenging property by DPPH radical scavenging and Ferric Reducing Antioxidant Power assays. The animals were treated with 200 mg/kg body wt. of pomegranate extracts and Ellagic acid for 15 days before exposure to 6 Gy of EBR. Radiation induced DNA damage was assessed by comet assay in the peripheral blood lymphocytes of mice. The biochemical estimations were carried out in the serum and RBC lysate of the animals. The plant extracts and synthetic compound exhibited good radical scavenging and reducing properties.The pretreated animals before irradiation caused a reduction in the comet length, olive tail moment, % DNA in tail when compared to irradiated group. The biochemical parameters such as lipid peroxidation was significantly depleted in the treated groups when compared to irradiated group followed by significant elevation in reduced glutathione. Our findings indicate the ameliorating effects of pomegranate extracts and synthetic ellagic acid on radiation induced DNA damage and biochemical changes in mice may be due to its free radical scavenging and increased antioxidant

Lipid-derived free radical production in superantigen-induced interstitial pneumonia

Science.gov (United States)

Miyakawa, Hisako; Mason, Ronald P.; Jiang, JinJie; Kadiiska, Maria B.

2009-01-01

We studied the free radical generation involved in the development of interstitial pneumonia (IP) in an animal model of autoimmune disease. We observed an electron spin resonance (ESR) spectrum of α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) radical adducts detected in the lipid extract of lungs in autoimmune-prone mice after intratracheal instillation of staphylococcal enterotoxin B. The POBN adducts detected by ESR were paralleled by infiltration of macrophages and neutrophils in the bronchoalveolar lavage fluid. To further investigate the mechanism of free radical generation, mice were pretreated with the macrophage toxicant gadolinium chloride, which significantly suppressed the radical generation. Free radical generation was also decreased by pretreatment with the xanthine oxidase (XO) inhibitor allopurinol, the iron chelator Desferal, and the inducible nitric oxide synthase (iNOS) inhibitor 1400W. Histopathologically, these drugs significantly reduced both the cell infiltration to alveolar septal walls and the synthesis of pulmonary collagen fibers. Experiments with NADPH oxidase knockout mice showed that NADPH oxidase did not contribute to lipid radical generation. These results suggest that lipid-derived carbon-centered free radical production is important in the manifestation of IP and that a macrophage toxicant, an XO inhibitor, an iron chelator, and an iNOS inhibitor protect against both radical generation and the manifestation of IP. PMID:19376221

Contribution of endogenous and exogenous damage to the total radiation-induced damage in the bacterial spore

International Nuclear Information System (INIS)

Jacobs, G.P.; Samuni, A.; Czapski, G.

1980-01-01

Radical scavengers such as polyethylene glycol 4000 and bovine albumin have been used to define the contribution of exogenous and endogenous damage to the total radiation-induced damage in aqueous buffered suspensions of Bacillus pumilus spores. The results indicate that this damage in the bacterial spore is predominantly endogenous

Applications of EPR in radiation research

CERN Document Server

Lund, Anders

2014-01-01

Applications of EPR in Radiation Research is a multi-author contributed volume presented in eight themes: I. Elementary radiation processes (in situ and low temperature radiolysis, quantum solids); II: Solid state radiation chemistry (crystalline, amorphous and heterogeneous systems); III: Biochemistry, biophysics and biology applications (radicals in biomaterials, spin trapping, free-radical-induced DNA damage); IV: Materials science (polymeric and electronic materials, materials for treatment of nuclear waste, irradiated food); V: Radiation metrology (EPR-dosimetry, retrospective and medical

Early mechanisms in radiation-induced biological damage

International Nuclear Information System (INIS)

Powers, E.L.

1983-01-01

An introduction to the mechanisms of radiation action in biological systems is presented. Several questions about the nature of the radiation damage process are discussed, including recognition of the oxygen effects, dose-response relationships, and the importance of the hydroxyl radical

Titanium dioxide induced cell damage: A proposed role of the carboxyl radical

Energy Technology Data Exchange (ETDEWEB)

Dodd, Nicholas J.F. [Ecotoxicology and Stress Biology Research Centre, School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Jha, Awadhesh N. [Ecotoxicology and Stress Biology Research Centre, School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)], E-mail: a.jha@plymouth.ac.uk

2009-01-15

Titanium dioxide (TiO{sub 2}) nanoparticles have been shown to be genotoxic to cells exposed to ultraviolet A (UVA) radiation. Using the technique of electron spin resonance (ESR) spin trapping, we have confirmed that the primary damaging species produced on irradiation of TiO{sub 2} nanoparticles is the hydroxyl (OH) radical. We have applied this technique to TiO{sub 2}-treated fish and mammalian cells under in vitro conditions and observed the additional formation of carboxyl radical anions (CO{sub 2}{sup -}) and superoxide radical anions (O{sub 2}{sup -}). This novel finding suggests a hitherto unreported pathway for damage, involving primary generation of OH radicals in the cytoplasm, which react to give CO{sub 2}{sup -} radicals. The latter may then react with cellular oxygen to form O{sub 2}{sup -} and genotoxic hydrogen peroxide (H{sub 2}O{sub 2})

Grape extract protects against γ-radiation-induced membrane damage strains of human erythrocytes

International Nuclear Information System (INIS)

Das, Subir Kumar

2017-01-01

The membrane integrity of circulating red blood cells (RBCs) is compromised by the deleterious actions of γ-radiation in humans. Grapes are the richest source of antioxidants due to presence of potentially bioactive phytochemicals. The objective of the present study was to assess the radioprotective actions of grape extracts against the γ-radiation-induced membrane permeability of human erythrocytes. The scavenging activities in seeds of grape in DPPH, hydrogen peroxide and hydroxyl radicals, were higher than skin or pulp of different cultivars. Grape extracts also showed appreciable extent of total antioxidant capacity and effective antihemolytic action. Grape extracts significantly ameliorated the γ-radiation-induced increase of the levels of thiobarbituric acid-reactive substances (TBARS, an index of lipid peroxidation) in the RBC membrane ghosts. Stored blood showed higher levels of K + ion as compared to the normal blood which was elevated by γ-radiation. Membrane ATPase was inhibited by the exposure to γ-radiation.Treatment of RBCs with the grape extracts prior to the exposure of γ-radiation significantly mitigated these changes in the erythrocyte membranes caused by the lower dose of radiation (4 Gy). (author)

Radioprotective effect of sulphydryl group containing triazole derivative to modulate the radiation-induced clastogenic effects

International Nuclear Information System (INIS)

Suchetha Kumari, N.; Madhu, L.N.

2012-01-01

Protection of biological systems against radiation damage is of paramount importance during accidental and unavoidable exposure to radiation. Several physico-chemical and biological factors collectively contribute to the damage caused by radiation and are, therefore, targets for developing radioprotectors. Chemicals capable of scavenging free radicals, relieving oxidative stress, promoting antioxidant activity and modulating immune response have been some of the radioprotectors extensively investigated with limited success. It has long been known that some of the most effective radioprotective agents are those which contain sulphydryl groups. The present study reports an evaluation of radical scavenging property and radioprotective property of sulphydryl group containing triazole derivative. The lethal dose of Electron beam radiation (EBR) was studied by survival assay. The dose reduction factor (DRF) of 4-amino-5-mercapto-3-methyl-1,2,4-triazole (TR1) was calculated by taking the ratio between LD 50 of EBR with and without TR1 treatment. Radical scavenging property of TR1 was assessed by DPPH radical scavenging assay. The clastogenic effects of EBR were recorded by Micronucleus test in bone marrow cells and DNA fragmentation assay in hepatic cells of mice. The survival assay results showed that 10Gy was the LD 50 of EBR. The calculated DRF for TR1 was found to be 1.2. DPPH radical scavenging assay showed a positive result when it compared with the standard glutathione. Treatment of mice with 100 mg of TR1 for 15 days before irradiation significantly (P<0.05) reduced the frequency of micronucleus formation in bone marrow cells and also reduced the DNA fragmentation in hepatic cells. The result obtained in the present study concludes that TR1 has a protective effect against the EBR-induced mortality and clastogenicity. (author)

Effects of ozone oxidative preconditioning on radiation-induced organ damage in rats

International Nuclear Information System (INIS)

Gultekin, Fatma Ayca; Bakkal, Bekir Hakan; Guven, Berrak; Tasdoven, Ilhan; Bektas, Sibel; Can, Murat; Comert, Mustafa

2013-01-01

Because radiation-induced cellular damage is attributed primarily to harmful effects of free radicals, molecules with direct free radical scavenging properties are particularly promising as radioprotectors. It has been demonstrated that controlled ozone administration may promote an adaptation to oxidative stress, preventing the damage induced by reactive oxygen species. Thus, we hypothesized that ozone would ameliorate oxidative damage caused by total body irradiation (TBI) with a single dose of 6 Gy in rat liver and ileum tissues. Rats were randomly divided into groups as follows: control group; saline-treated and irradiated (IR) groups; and ozone oxidative preconditioning (OOP) and IR groups. Animals were exposed to TBI after a 5-day intraperitoneal pretreatment with either saline or ozone (1 mg/kg/day). They were decapitated at either 6 h or 72 h after TBI. Plasma, liver and ileum samples were obtained. Serum AST, ALT and TNF-α levels were elevated in the IR groups compared with the control group and were decreased after treatment with OOP. TBI resulted in a significant increase in the levels of MDA in the liver and ileal tissues and a decrease of SOD activities. The results demonstrated that the levels of MDA liver and ileal tissues in irradiated rats that were pretreated with ozone were significantly decreased, while SOD activities were significantly increased. OOP reversed all histopathological alterations induced by irradiation. In conclusion, data obtained from this study indicated that ozone could increase the endogenous antioxidant defense mechanism in rats and there by protect the animals from radiation-induced organ toxicity. (author)

Radiation-induced apoptosis

International Nuclear Information System (INIS)

Ohyama, Harumi

1995-01-01

Apoptosis is an active process of gene-directed cellular self-destruction that can be induced in many cell types via numerous physiological and pathological stimuli. We found that interphasedeath of thymocytes is a typical apoptosis showing the characteristic features of apoptosis including cell shrinkage, chromatin condensation and DNA degradation. Moderate dose of radiation induces extensive apoptosis in rapidly proliferating cell population such as the epithelium of intestinal crypt. Recent reports indicate that the ultimate form of radiation-induced mitotic death in several cells is also apoptosis. One of the hallmarks of apoptosis is the enzymatic internucleosomal degradation of chromatin DNA. We identified an endonuclease responsible for the radiation-induced DNA degradation in rat thymocytes. The death-sparing effects of interrupting RNA and protein synthesis suggested a cell genetic program for apoptosis. Apoptosis of thymocytes initiated by DNA damage, such as radiation and radio mimetic substance, absolutely requires the protein of p53 cancer suppresser gene. The cell death induced by glucocorticoid, or aging, has no such requirement. Expression of oncogene bcl-2 rescues cells from the apoptosis. Massive apoptosis in radiosensitive cells induced by higher dose radiation may be fatal. It is suggested that selective apoptotic elimination of cells would play an important role for protection against carcinogenesis and malformation through removal of cells with unrepaired radiation-induced DNA damages. Data to evaluate the significance of apoptosis in the radiation risk are still poor. Further research should be done in order to clarify the roles of the cell death on the acute and late effects of irradiation. (author)

Investigation of induced changes after treatment with ionizing radiation and saturated steam in the case of paprika

International Nuclear Information System (INIS)

Kispeter, J.; Bajusz-Kabok, K.; Fekete, M.; Szabo, G.; Fodor, E.; Pali, T.

2002-01-01

Complete text of publication follows. Beside conventional food preservation methods, such new physical methods are also applied as ionising radiation, high hydrostatic pressure, high-tension gradient, fluctuating strong magnetic field as well as treatments with high-pressure saturated steam and microwaves. Since radiation treatment is the best known, it can be regarded as a basic method in comparative tests. In our work the preservation-induced changes were investigated for paprika griests of various origin and quality (different dyestuff contents). Samples were treated with ionising radiation, high-pressure saturated steam (140 deg C, 30 s) or with combinations of these. The changes were followed as a function of absorbed dose (2, 5, 7.5, 10 kGy) and storage time (0, 1, 2, 4, 12 weeks) using colour measurements, rheological and ESR methods. Our results are summarised as follows: (1) The treatment with high-pressure saturated steam is equivalent to that of 5 kGy absorbed γ-doses. Significant changes in dyestuff contents and surface colours can't be detected immediately after treatments. After storage of 12 weeks, decomposition of dyestuffs and changes in surface colours in samples treated with saturated steam are 20% greater than in control. Radiation results in a slight (few %) dyestuff decomposition and colour change (i.e. discolouration). (2) Rheological characteristics were changed in both treatments (apparent viscosities were increased) during storage. This is a reversible and permanent change in the case of treatments with ionising radiation and with high-pressure saturated steam, respectively. (3) Changes induced by microwave treatment are in accordance with rheological changes. (4) Treatment with saturated steam results in a decrease in the cellulose free radical content. The decrease is inversely proportional to dyestuff contents. (5) Decrease of cellulose radical concentration with the storage time is of exponential-like character. Radicals disappear at

Characterization of γ-radiation induced polymerization in ethyl methacrylate and methyl acrylate monomers solutions

Science.gov (United States)

Baccaro, Stefania; Casieri, Cinzia; Cemmi, Alessia; Chiarini, Marco; D'Aiuto, Virginia; Tortora, Mariagrazia

2017-12-01

The present work is focused on the γ-radiation induced polymerization of ethyl methacrylate (EMA) and methyl acrylate (MA) monomers mixture to obtain a co-polymer with specific features. The effect of the irradiation parameters (radiation absorbed dose, dose rate) and of the environmental atmosphere on the features of the final products was investigated. Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Nuclear Magnetic Resonance high-resolution analyses of hydrogen and carbon nuclei (1H and 13C NMR) were applied to follow the γ-induced modifications by monitoring the co-polymerization process and allowed the irradiation parameters optimization. Diffusion-Ordered NMR (DOSY-NMR) data were used to evaluate the co-polymers polydispersity and polymerization degree. Since the last parameter is strongly influenced by the γ radiation and environmental conditions, a comparison among samples prepared and irradiated in air and under nitrogen atmosphere was carried out. In presence of oxygen, higher radiation was required to obtain a full solid co-polymer since a partial amount of energy released to the samples was involved in competitive processes, i.e. oxygen-containing free radicals formation and primary radicals recombination. Irrespectively to the environmental atmosphere, more homogeneous samples in term of polymerization degree dispersion was achieved at lower dose rates. At radiation absorbed doses higher than those needed for the formation of the co-polymer, while in case of samples irradiated in air heavy depolymerization was verified, a sensible increase of the samples stability was attained if the irradiation was performed under nitrogen atmosphere.

Study of Radiation Induced Radicals in HAP and β-TCP Based Bone Graft Materials by ERP Spectroscopy

International Nuclear Information System (INIS)

Maltar-Strmecki, N.; Matkovic, I.

2013-01-01

Calcium phosphates such as beta-tricalcium phosphate (β-TCP) and hydroxyapatite (HAP) are frequently used as dental implants due to proven excellent biocompatibility. Because of their resorption in the body and direct contact with tissues, in order to inactivate bacteria, fungal spores and viruses, they are usually sterilized by γ-irradiation. However, literature provides little information about effects of γ-irradiation on the formation and stability of the free radicals in the bone graft materials during and after sterilization procedure. In this study EPR (electron paramagnetic resonance) spectroscopy was used to investigate HAP and β-TCP based dental implants present on the market. Eight dental graft materials present on the market were investigated: Bioresorb R Macropore, Poresorb R -TCP, Easy-Graft T M and Cerasorb R synthetic β-tricalcium phosphates, Easy-Graft T M crystal and Ossceram R two phase synthetic CaP consisting of 60 % HAP and 40 % β-TCP, and Dexabone R and Bio-Oss R bone graft material of bovine origin. EPR study shows that this is the only technique for characterization of free radicals that can simultaneously determine not only the presence and content, but also the position and the structure of free radicals formed by γ-sterilization in the investigated materials, as well as the paramagnetic substitutions incorporated in the materials during the synthesis (such as Mn 2+ , Fe 3+ or Cr 2+ ). Additionally, EPR provides information on stability of irradiation-induced radicals (CO 2 - , trapped H-atoms, NO 3 2 etc.) and processes for reducing them. Results show that EPR should be considered as a valuable technique in improving the quality of bone graft materials, which must be sterile, and to offer the high quality, efficacy and reliable materials to the patients.(author)

Time-resolved studies of direct effects of radiation on DNA

International Nuclear Information System (INIS)

Fielden, E.M.; O'Neill, P.; Al-Kazwini, A.

1987-01-01

The biological changes induced by ionising radiation are a consequence of radiation-induced chemical events taking place at times <1s. These events are strongly influenced by the presence of chemical modifiers. Since DNA is a principle target for radiation-induced cell killing, DNA-free radicals are generated by direct ionisation of DNA moieties (direct effect) and by reaction with hydroxyl radicals formed by radiolysis of the water which is in the vicinity of the DNA (indirect effect). In order to study the 'direct' effects of radiation on DNA the following model approaches are discussed:- 1) Use of the technique of pulse radiolysis to investigate in aqueous solution the interactions of deoxynucleosides with SO/sub 4//sup .-/ whereby one-electron oxidised species of the bases are generated; and 2) time resolved, radiation-induced changes to solid DNA and related macromolecules (e.g. radiation-induced luminescence) in order to obtain an understanding of charge/energy migration as a result of ionisation of DNA. The influence of chemical modifiers and of environment is discussed in terms of the properties of the radiation-induced species produced. Since the properties of base radicals produced by SO/sub 4//sup .-/ are similar to those of the base OH-adducts oxidising properties, potential similarities between the 'direct' and 'indirect' effects of radiation are presented

The Possible Protective Role of Curcumin against Radiation Induced Cytogenetic Damages in Mice

International Nuclear Information System (INIS)

Hassan, M.R.M.

2014-01-01

This study was undertaken to investigate the effect of curcumin on radiation induced damages in albino male mice. Animals were injected intraperitoneally with 20 mg/kg body weight curcumin 30 minutes prior to whole body gamma-irradiation (4Gy). Animals were sacrificed after 1, 3 and 7 days of the irradiation. The possible radioprotective effect of curcumin on bone marrow chromosomes, DNA fragmentation, superoxide dismutase (SOD) activity, reduced glutathione (GSH) content, malondialdehyde (MDA) level, total free radicals in spleen, and peripheral blood differential count was examined at the different time intervals of the experiment. Radiation exposure resulted in a statistically significant elevation in the percentage of the aberrant metaphases, total amount of chromosomal damage, percentage of the DNA fragmentation, (MDA) level, decline in the activities of (SOD) and (GSH) contents, at 1, 3 and 7 days post-irradiation, elevation in the total free radicals one day post-irradiation and percentage of the total number of normal and abnormal white blood cells after 1, 3 days of irradiation specially the abnormal lymphocytes and neutrophils. Curcumin showed a clastogenic effect that it caused elevation of the total number of aberrant cells, structural and numerical aberrant cells after 1 and 3 days of the experiment. Moreover, curcumin caused a decline in the liver (GSH) content after 1, 3 and 7 days of the experiment. On the other hand, intraperitoneal injection of curcumin before irradiation didn‘t show any protective effect on the total aberrant cells and structural aberrant cells induced by irradiation, liver (GSH) content and the percentage of the DNA fragmentation, liver (MDA) level and number of abnormal leukocytes. In contrast, it showed potentiating effect on the numerical type aberrations especially endomitosis after one day post-irradiation. In addition, elevation in the percentage of the total free radicals induced by curcumin 3 and 7 days post

Amelioration of ionizing radiation induced lipid peroxidation in mouse liver by Moringa oleifera Lam. leaf extract

International Nuclear Information System (INIS)

Sinha, Mahuya; Das, Dipesh Kr; Dey, Sanjit; Datta, Sanjukta; Ghosh, Santinath

2012-01-01

Protective effect of Moringa oleifera leaf extract (MoLE) against radiation-induced lipid peroxidation has been investigated. Swiss albino mice, selected from an inbred colony, were administered with MoLE (300 mg/kg body wt) for 15 days before exposing to a single dose of 5 Gy 60 Co-gamma radiation. After treatments, animals were necropsied at different post irradiation intervals (days 1, 7 and 15) and hepatic lipid peroxidation and reduced glutathione (GSH) contents were estimated to observe the relative changes due to irradiation and its possible amelioration by MoLE. It was observed that, MoLE treatment restored GSH in liver and prevented radiation induced augmentation in hepatic lipid peroxidation. Phytochemical analysis showed that MoLE possess various phytochemicals such as ascorbic acid, phenolics (catechin, epicatechin, ferulic acid, ellagic acid, myricetin) etc., which may play the key role in prevention of hepatic lipid peroxidation by scavenging radiation induced free radicals. (author)

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-12-15

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

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

International Nuclear Information System (INIS)

Wright, E.G.

2008-01-01

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

Reaction pathway of the degradation of the p-hydroxybenzoic acid by sulfate radical generated by ionizing radiations

International Nuclear Information System (INIS)

Criquet, Justine; Leitner, Nathalie Karpel Vel

2015-01-01

The degradation of p-hydroxybenzoic acid (HBA) in aqueous solutions by ionizing radiation was studied. The phenolic pollutant was easily removed by the electron beam irradiation, as more than 80% of the initial 100 µM introduced was degraded for a dose of 600 Gy. It was shown that the addition of persulfate, producing the sulfate radical as additional reactive species, induced a change in the reaction pathway. LC–MS analyses were performed in order to identify the different by-products formed. In the absence of persulfate, the main by-product formed was 3,4-dihydroxybenzoic acid, while in presence of persulfate, 1,4-benzoquinone was detected and the hydroxylated by-products were not present. A reaction pathway of HBA degradation by hydroxyl and sulfate radicals was proposed from the identification of the chemical structure of the different by-products detected. The influences of pH and dissolved oxygen were also studied. A high decline of HBA degradation was observed at pH 11 compared to pH 4.5, this decrease was minimized in the presence of persulfate. The dissolved oxygen concentration was found to be a limiting parameter of HBA degradation, however an excess of dissolved oxygen in solution did not improve the degradation to a large extent. - Highlights: • p-Hydroxybenzoic acid (HBA) is easily removed by e-beam irradiation. • The sulfate radicals formed from persulfate induce loss of the benzoic acid skeleton. • The dissolved oxygen concentration is a limiting parameter of the HBA degradation. • The effect of pH is minimized in presence of persulfate

Ascorbic acid (AA) metabolism in protection against radiation damage

International Nuclear Information System (INIS)

Rose, R.C.; Koch, M.J.

1986-01-01

The possibility is considered that AA protects tissues against radiation damage by scavenging free radicals that result from radiolysis of water. A physiologic buffer (pH 6.7) was incubated with 14 C-AA and 1 mM thiourea (to slow spontaneous oxidation of AA). Aliquots were assayed by HPLC and scintillation spectrometry to identify the 14 C-label. Samples exposed to Cobalt-60 radiation had a half time of AA decay of 30 minutes) indicating that AA scavenges radiation-induced free radicals and forms the ascorbate free radical (AFR). Pairs of 14 C-AFR disproportionate, with the net effect of 14 C-dehydroascorbic acid formation from 14 C-AA. Having established that AFR result from ionizing radiation in an aqueous solution, the possibility was evaluated that a tissue factor reduces AFR. Cortical tissue from the kidneys of male rats was minced, homogenized in buffer and centrifuged at 8000 xg. The supernatant was found to slow the rate of radiation-induced AA degradation by > 90% when incubated at 23 0 C in the presence of 15 μM 14 C-AA. Samples of supernatant maintained at 100 0 C for 10 minutes or precipitated with 5% PCA did not prevent radiation-induced AA degradation. AA may have a specific role in scavenging free radicals generated by ionizing radiation and thereby protect body tissues

The kinetics of the radiation-induced chain dechlorination of hexachloroethane in alcohols

International Nuclear Information System (INIS)

Sawai, Takeshi; Ohara, Naoki; Shimokawa, Toshinari

1978-01-01

The kinetics of the radiation-induced dechlorination of hexachloroethane was investigated in deoxygenated alcohol solutions. The major products were hydrogen chloride, pentachloroethane, 1,1,2,2-tetrachloroethane, tetrachloroethylene, and aldehydes or acetone. No 1,1,1,2-tetrachloroethane was observed. The radiation-chemical yields of these products and the disappearance of hexachloroethane were quite high; these facts indicate that a chain reaction is involved in these processes. After the hexachloroethane had effectively dechlorinated down to tetrachloro compounds, there were no marked changes in the lower chlorinated compound upon continuous irradiation. Tetrachloroethane was formed via pentachloroethane, but tetrachloroethylene was produced by means of C 2 Cl 5 →C 2 Cl 4 + cl reaction and the yield was particularly high in methanol compared with the other alcohols. The chain length of the dechlorination from hexachloroethane to pentachloroethane and from pentachloroethane to tetrachloroethane increased in the order of 2-propanol>ethanol>methanol. The G(-C 2 Cl 6 ) and G(products) were proportional to (dose rate)sup(-1/2), and the ratio of G(C 2 HCl 5 ) to G(C 2 Cl 4 ) was a constant in each alcohol solution, regardless of the dose rate. The α-hydroxy alkyl radical is the chain carrier for the dechlorination reaction of hexachloroethane in alcohol solutions. The relative rates of the dechlorination were found to be 1, 3, and 14 for C*H 2 OH (*: radical), CH 3 C*HOH (*: radical), and (CH 3 ) 2 C*OH (*: radical), respectively. The order in the rate is in agreement with that of the redox potential of these radicals. The effect of the irradiation temperature on the products yields was also examined. (auth.)

Protective role of Tinospora cordifolia extract against radiation-induced qualitative, quantitative and biochemical alterations in testes

International Nuclear Information System (INIS)

Sharma, Priyanka; Parmar, Jyoti; Sharma, Priyanka; Verma, Preeti; Goyal, P.K.

2012-01-01

In today's changing global scenario, ionizing radiation is considered as most potent cause of oxidative stress mediated by free radical flux which induces severe damage at various hierarchical levels in the organization in the living organisms. Testis is a highly prolific tissue with fast cellular renewal and poor antioxidant defense; therefore it becomes an easy target for the radiation-induced free radicals that have long been suggested as major cause of male infertility. Chemical radioprotection is an important strategy to countermeasure the deleterious effects of radiation. Several Indian medicinal plants are rich source of antioxidants and these have been used for the treatment of ailments. Tinospora cordifolia, commonly known as amrita, is one of the plants that have several pharmacological and therapeutic properties. Therefore, the present study was performed to evaluate the deleterious effects of semi lethal dose of gamma radiation on testicular tissue and their possible inhibition by Tinospora cordifolia root extract (TCE). For this purpose, healthy Swiss albino male mice were selected from an inbred colony and divided into four groups. Group I (normal) was administered double distilled water (DDW) volume equal to TCE (75 mg/kg.b.wt/animal) by oral gavage. Group II was orally supplemented TCE as 75 mg/kg. b.wt once daily for 5 consecutive days. Group III (irradiated control) received DDW orally equivalent to TCE for 5 days then exposed to 5 Gy gamma radiation. Group IV (experimental) was administered TCE as in Group II and exposed to radiation (as in Group III). Irradiation resulted into significant decrease in the frequency of different spermatogenic cell counts along with severe histo-pathological lesions up to 7th day of irradiation in testes of irradiated control animals, thereafter, recovery followed towards the normal architecture. TCE pretreatment effectively prevented radiation induced such alterations in cellular counts and testicular injuries by

Investigation of pUC19 DNA damage induced by direct and indirect effect of 7Li ions radiation

International Nuclear Information System (INIS)

Sui Li; Zhao Kui; Guo Jiyu; Ni Meinan; Kong Fuquan; Cai Minghui; Yang Mingjian

2006-01-01

The effect of direct and indirect action on DNA damage in 7 Li ions radiation is investigated. Using 7 Li ions generated by HI-13 tandem accelerator, three conditions of pUC19 plasmid DNA samples including dry, with or without mannitol are irradiated at different doses in air. These irradiated DNA samples are analyzed with atomic force microscopy (AFM) in nanometer-scale. The changes of DNA forms as the dose increases are observed. The results show that free radical is the main factor in DNA strand breaks induced by 7 Li ions radiation under condition of aqueous solution. The mannitol can effectively scavenge free radical and reduce the yields of DNA strand breaks. The experimental results of this report can offered valuable basal data for cancer therapy by boron neutron capture therapy (BNCT) or heavy ion radiation method, etc. (author)

Effect of radiation quality on radical formation in ion-irradiated solid alanine

Energy Technology Data Exchange (ETDEWEB)

Koizumi, Hitoshi; Ichikawa, Tsuneki; Yoshida, Hiroshi [Hokkaido Univ., Sapporo (Japan); Namba, Hideki; Taguchi, Mitsumasa; Kojima, Takuji

1997-03-01

Radical formation in solid alanine irradiated with H{sup +} and He{sup +} ions of 0.5-3.0 MeV and with heavy ions of hundreds of MeV was examined by the ESR method. Radical yield is constant below a critical fluence, and the yield decreases above the fluence. The critical fluence for the H{sup +} and He{sup +} ions is about 10{sup 12} ions cm{sup -2}, while the critical fluence for the heavy ions is 10{sup 10}-10{sup 11} ions cm{sup -2}. G-value of the radical formation (radicals per 100 eV absorbed dose) is obtained from the constant yield at the low fluences. The G-value depends on the radiation quality. This dependence is ascribed to the difference of local dose in the ion tracks. The fluence-yield curves were simulated with a model assuming cylindrical shape of ion tracks and dose-yield relationship for {gamma}-irradiation. This model well explains the fluence-yield curves for the ion irradiations. (author)

Free Radicals and Extrinsic Skin Aging

Directory of Open Access Journals (Sweden)

Borut Poljšak

2012-01-01

Full Text Available Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR. It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2−•, hydrogen peroxide (H2O2, hydroxyl radical (OH•, and singlet oxygen (1O2. The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants and antioxidants we consume from the food (vitamin A, C, E, etc.. The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

High-frequency electromagnetic radiation and the production of free radicals in four mouse organs

Czech Academy of Sciences Publication Activity Database

Barcal, J.; Stopka, Pavel; Křížová, Jana; Vrba, J.; Vožeh, F.

2014-01-01

Roč. 56, 1-2 (2014), s. 9-14 ISSN 1337-933X Institutional support: RVO:61388980 Keywords : Free radicals * Mobile phones * Paramagnetic resonance spectroscopy * Radiation Subject RIV: CA - Inorganic Chemistry

Transformations of dissolved organic matter induced by UV photolysis, Hydroxyl radicals, chlorine radicals, and sulfate radicals in aqueous-phase UV-Based advanced oxidation processes.

Science.gov (United States)

Varanasi, Lathika; Coscarelli, Erica; Khaksari, Maryam; Mazzoleni, Lynn R; Minakata, Daisuke

2018-05-15

Considering the increasing identification of trace organic contaminants in natural aquatic environments, the removal of trace organic contaminants from water or wastewater discharge is an urgent task. Ultraviolet (UV) and UV-based advanced oxidation processes (AOPs), such as UV/hydrogen peroxide (UV/H 2 O 2 ), UV/free chlorine and UV/persulfate, are attractive and promising approaches for the removal of these contaminants due to the high reactivity of active radical species produced in these UV-AOPs with a wide variety of organic contaminants. However, the removal efficiency of trace contaminants is greatly affected by the presence of background dissolved organic matter (DOM). In this study, we use ultrahigh resolution mass spectrometry to evaluate the transformation of a standard Suwanee River fulvic acid DOM isolate in UV photolysis and UV-AOPs. The use of probe compounds allows for the determination of the steady-state concentrations of active radical species in each UV-AOP. The changes in the H/C and O/C elemental ratios, double bond equivalents, and the low-molecular-weight transformation product concentrations of organic acids reveal that different DOM transformation patterns are induced by each UV-AOP. By comparison with the known reactivities of each radical species with specific organic compounds, we mechanistically and systematically elucidate the molecular-level DOM transformation pathways induced by hydroxyl, chlorine, and sulfate radicals in UV-AOPs. We find that there is a distinct transformation in the aliphatic components of DOM due to HO• in UV/H 2 O 2 and UV/free chlorine. Cl• induced transformation of olefinic species is also observed in the UV/free chlorine system. Transformation of aromatic and olefinic moieties by SO 4 •- are the predominant pathways in the UV/persulfate system. Copyright © 2018 Elsevier Ltd. All rights reserved.

The yield, processing, and biological consequences of clustered DNA damage induced by ionizing radiation

International Nuclear Information System (INIS)

Shikazono, Naoya; Noguchi, Miho; Fujii, Kentaro; Urushibara, Ayumi; Yokoya, Akinari

2009-01-01

After living cells are exposed to ionizing radiation, a variety of chemical modifications of DNA are induced either directly by ionization of DNA or indirectly through interactions with water-derived radicals. The DNA lesions include single strand breaks (SSB), base lesions, sugar damage, and apurinic/apyrimidinic sites (AP sites). Clustered DNA damage, which is defined as two or more of such lesions within one to two helical turns of DNA induced by a single radiation track, is considered to be a unique feature of ionizing radiation. A double strand break (DSB) is a type of clustered DNA damage, in which single strand breaks are formed on opposite strands in close proximity. Formation and repair of DSBs have been studied in great detail over the years as they have been linked to important biological endpoints, such as cell death, loss of genetic material, chromosome aberration. Although non-DSB clustered DNA damage has received less attention, there is growing evidence of its biological significance. This review focuses on the current understanding of (1) the yield of non-DSB clustered damage induced by ionizing radiation (2) the processing, and (3) biological consequences of non-DSB clustered DNA damage. (author)

Effects of scavengers of reactive oxygen and radical species on cell survival following photodynamic treatment in vitro: comparison to ionizing radiation

International Nuclear Information System (INIS)

Henderson, B.W.; Miller, A.C.

1986-01-01

The effects of various scavengers of reactive oxygen and/or radical species on cell survival in vitro of EMT6 and CHO cells following photodynamic therapy (PDT) or gamma irradiation were compared. None of the agents used exhibited major direct cytotoxicity. Likewise, none interfered with cellular porphyrin uptake, and none except tryptophan altered singlet oxygen production during porphyrin illumination. The radioprotector cysteamine (MEA) was equally effective in reducing cell damage in both modalities. In part, this protection seems to have been induced by oxygen consumption in the system due to MEA autoxidation under formation of H 2 O 2 . The addition of catalase, which prevents H 2 O 2 buildup, reduced the effect of MEA to the same extent in both treatments. Whether the remaining protection was due to MEA's radical-reducing action or some remaining oxygen limitation is unclear. The protective action of MEA was not mediated by a doubling of cellular glutathione levels, since addition of buthionine sulfoximine, which prevented glutathione increase, did not diminish the observed MEA protection. The hydroxyl radical scavenger mannitol also afforded protection in both, but it was approximately twice as effective in gamma irradiation as in PDT. This is consistent with the predominant role of OH radicals in ionizing radiation damage and their presumed minor involvement in PDT damage. Superoxide dismutase, a scavenger of O 2 , acted as a radiation protector but was not significantly effective in PDT. Catalase, which scavenges H 2 O 2 , was ineffective in both modalities. Tryptophan, an efficient singlet oxygen scavenger, reduced cell death through PDT by several orders of magnitude while being totally ineffective in gamma irradiation. These data reaffirm the predominant role of 1O2 in the photodynamic cell killing but also indicate some involvement of free radical species

Transient nutation electron spin resonance spectroscopy on spin-correlated radical pairs: A theoretical analysis on hyperfine-induced nuclear modulations

Science.gov (United States)

Weber, Stefan; Kothe, Gerd; Norris, James R.

1997-04-01

The influence of anisotropic hyperfine interaction on transient nutation electron paramagnetic resonance (EPR) of light-induced spin-correlated radical pairs is studied theoretically using the density operator formalism. Analytical expressions for the time evolution of the transient EPR signal during selective microwave excitation of single transitions are derived for a model system comprised of a weakly coupled radical pair and one hyperfine-coupled nucleus with I=1/2. Zero-quantum electron coherence and single-quantum nuclear coherence are created as a result of the sudden light-induced generation of the radical pair state from a singlet-state precursor. Depending on the relative sizes of the nuclear Zeeman frequency and the secular and pseudo-secular parts of the hyperfine coupling, transitions between levels with different nuclear spin orientations are predicted to modulate the time-dependent EPR signal. These modulations are in addition to the well-known transient nutations and electron zero-quantum precessions. Our calculations provide insight into the mechanism of recent experimental observations of coherent nuclear modulations in the time-resolved EPR signals of doublets and radical pairs. Two distinct mechanisms of the modulations are presented for various microwave magnetic field strengths. The first modulation scheme arises from electron and nuclear coherences initiated by the laser excitation pulse and is "read out" by the weak microwave magnetic field. While the relative modulation depth of these oscillations with respect to the signal intensity is independent of the Rabi frequency, ω1, the frequencies of this coherence phenomenon are modulated by the effective microwave amplitude and determined by the nuclear Zeeman interaction and hyperfine coupling constants as well as the electron-electron spin exchange and dipolar interactions between the two radical pair halves. In a second mechanism the modulations are both created and detected by the microwave

DMA mitigates ionizing radiation induced damage in Balb/c mice through Akt/NFκB/PTEN pathway

International Nuclear Information System (INIS)

Tiwari, Vinod; Ranjan, Atul; Tandon, Vibha

2014-01-01

Ionizing radiation is associated with massive apoptosis in tumor as well as in radiosensitive organs. DMA, (5-(4-methylpiperazin-1-yl)-2-(2'-(3,4-dimethoxy-phenyl)-5'-benzimidazolyl) a cytoprotective radiomodulator, work in dual mode of action as free radical quencher and modifier of genomic instability caused by radiation. We observed 34% radioprotection with 50 mg/Kg bw intravenous dose of DMA in Balb/c mice at 8 Gy. DMA treatment before irradiation restored the normal crypts and villi architecture in Balb/c mice. The villi height was restored equivalent to control group in DMA treated animals, whereas, it was degenerated in irradiated animals. IR-induced apoptosis was reduced in spleen in presence of DMA as a result of preservation of splenic lymphocytes from radiation. This clearly exhibits the radioprotective ability of DMA to mitigate radiation induced tissue damage. IR-induced S phase check point was overcome by DMA. DMA promoted activation and phosphorylation of GSK3β through the activation of Akt in Balb/c mice. There was reduction in PTEN level in DMA pretreated mice where as it was upregulated in irradiated mice. Relative enhanced kinase activity of Akt was observed in DMA treated Balb/c mice and irradiated A549, MRC5 cell lines. There was no significant radioprotection in DMA treated Akt siRNA transfected cells in comparison to only Akt siRNA transfected cells with increasing dose of radiation. Akt activation was found in a dose-dependent manner by DMA through Luciferase reporter assay. We observed that DMA treated HEK cells transfected with control siRNA, resulted in less early apoptotic cells within 24h, but radiation (5 Gy) treated cells showed 20% early apoptotic cells within 3 h which were reduced to 12% at 3 h, 9% at 6 h and 8% at 24 h in DMA+radiation treated cells determined by Annexin V binding assay. Further molecular mRNA expression analysis of key regulatory genes unveil that DMA inhibited p21 and augmented Akt and Gadd45 in

Kinetics of the radicals induced in gamma irradiated sulfafurazole: an EPR study

International Nuclear Information System (INIS)

Colak, S.; Korkmaz, M.

2004-01-01

The spectroscopic and kinetic features of the radiolytic intermediates produced in gamma irradiated sulfafurazole (SFZ) were investigated at different temperatures in the dose range 5-50 kGy using EPR and IR techniques. The imodiation produced two species (A, B) in SFZ. The heights of the peaks were used to monitor the temperature, time dependent and kinetic features of the radical species contributing to the EPR spectrum. The applicability of EPR technique for monitoring radiosterilization of SFZ is discussed. The radiation yield of solid SFZ was found to be very low (G=0.16), and basing on this it was concluded that SFZ and SFZ containing drugs can be safely sterilized by radiation. The EPR data were used to characterize the contributing radicals produced in gamma irradiated SFZ. No definite difference was observed between unirradiated and irradiated IR spectra of SFZ. (orig.)

Radical surgery in patients with residual disease after (chemo)radiation for cervical cancer

NARCIS (Netherlands)

Boers, Aniek; Arts, Henriette J. G.; Klip, Harry; Nijhuis, Esther R.; Pras, Elisabeth; Hollema, Harry; Wisman, G. Bea A.; Nijman, Hans W.; Mourits, Marian J. E.; Reyners, Anna K. L.; de Bock, Geertruida H.; Thomas, Gillian; van der Zee, Ate G. J.

Objective: The aim of this study was to determine possible impact of routinely scheduled biopsies and more radical surgery for residual central disease in locally advanced cervical cancer after (chemo) radiation. Methods/Materials: Data were analyzed of a consecutive series of cervical cancer

Radiation-induced cranial nerve palsy

International Nuclear Information System (INIS)

Berger, P.S.; Bataini, J.P.

1977-01-01

Twenty-five patients with 35 cranial nerve palsies were seen at the Fondation Curie during follow-up after radical radiotherapy for head and neck tumors. The twelfth nerve was involved in 19 cases, the tenth in nine, and the eleventh in five; the fifth and second nerves were involved once each and in the same patient. The twelfth nerve was involved alone in 16 patients and the tenth nerve alone in three, with multiple nerves involved in the remaining six patients. The palsy was noted from 12 to 145 months after diagnosis of the tumor. The latency period could be correlated with dose so that the least square fit equation representing NSD vs delay is NSD = 2598--Delay (in months) x 4.6, with a correlation coefficient of -0.58. The distinction between tumor recurrence and radiation-induced nerve palsy is critical. It can often be inferred from the latency period but must be confirmed by observation over a period of time

Ion irradiation and biomolecular radiation damage II. Indirect effect

OpenAIRE

Wang, Wei; Yu, Zengliang; Su, Wenhui

2010-01-01

It has been reported that damage of genome in a living cell by ionizing radiation is about one-third direct and two-thirds indirect. The former which has been introduced in our last paper, concerns direct energy deposition and ionizing reactions in the biomolecules; the latter results from radiation induced reactive species (mainly radicals) in the medium (mainly water) surrounding the biomolecules. In this review, a short description of ion implantation induced radical formation in water is ...

Protective effects of vitamin glycosides on γ-radiation and H2O2-induced decomposition of thymine in aqueous solutions

International Nuclear Information System (INIS)

Shadyro, O.; Lagutin, P.; Edimecheva, I.; Brinkevich, S.; Kagiya, Tsutomu

2008-01-01

Effects of ascorbic acid (AA), ascorbic acid glycoside (AAG) and α-tocopherol monoglycoside (TMG) on radiation- and H 2 O 2 -induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, AAG was found to possess the most marked protector properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of AA and AAG, as well as properties of radical adducts formed during their interaction with OH radicals. (author)

Two-photon laser-induced fluorescence studies of HS radicals, DS radicals, and I atoms

Energy Technology Data Exchange (ETDEWEB)

Tiee, J J; Ferris, M J; Loge, G W; Wampler, F B

1983-04-15

A two-photon laser-induced excitation and fluorescence technique has been used to study the A /sup 2/..sigma../sup +/ - X/sup 2/PI transition of HS and DS radicals and various high-lying /sup 4/P/sup 0/, /sup 2/D/sup 0/, and /sup 4/D/sup 0/ states of the I atom. The two-photon excitation cross sections and detection sensitivity are discussed. 13 references, 5 figures.

A case of radiation-induced skin cancer of the neck

International Nuclear Information System (INIS)

Matsushita, Tetsuya; Susuki, Takeo; Kikui, Tomoko; Masada, Yoshiko; Tahara, Shinya.

1994-01-01

The authors discuss the case of radiation-induced skin cancer of the neck in a 76-year-old woman who had undergone irradiation of tubercular lymphadenitis of the cervix while in her low teens. Some fifty years later, a squamous cell carcinoma developed in the irradiated region and in due course deeply invaded the sternocleidomastoidous muscle. Thus, a radical neck dissection was performed and the tumor and the lymph tissue removed en bloc, after which reconstruction was accomplished by using a latissimus dorsi musculocutaneous flap. With regard to the lessons learned from treating this case, three points are considered important and are listed below. When treating radiation-induced skin cancer patients, the head and neck regions should be examined in detail for the presence of other tumors. The excision of the skin surrounding the tumor should be as wide as possible, so as to remove skin that may have been also over-subjected to irradiation. The remaining skin surrounding the defect left by the excision is atrophic and thin. (author)

Comparison of fluorescence-based techniques for the quantification of particle-induced hydroxyl radicals

Directory of Open Access Journals (Sweden)

Cohn Corey A

2008-02-01

Full Text Available Abstract Background Reactive oxygen species including hydroxyl radicals can cause oxidative stress and mutations. Inhaled particulate matter can trigger formation of hydroxyl radicals, which have been implicated as one of the causes of particulate-induced lung disease. The extreme reactivity of hydroxyl radicals presents challenges to their detection and quantification. Here, three fluorescein derivatives [aminophenyl fluorescamine (APF, amplex ultrared, and dichlorofluorescein (DCFH] and two radical species, proxyl fluorescamine and tempo-9-ac have been compared for their usefulness to measure hydroxyl radicals generated in two different systems: a solution containing ferrous iron and a suspension of pyrite particles. Results APF, amplex ultrared, and DCFH react similarly to the presence of hydroxyl radicals. Proxyl fluorescamine and tempo-9-ac do not react with hydroxyl radicals directly, which reduces their sensitivity. Since both DCFH and amplex ultrared will react with reactive oxygen species other than hydroxyl radicals and another highly reactive species, peroxynitite, they lack specificity. Conclusion The most useful probe evaluated here for hydroxyl radicals formed from cell-free particle suspensions is APF due to its sensitivity and selectivity.

The contribution of endogenous and exogenous effects to radiation-induced damage in the bacterial spore

International Nuclear Information System (INIS)

Jacobs, G.P.; Samuni, A.; Czapski, G.

1985-01-01

Radical scavengers such as polyethylene glycol 400 and 4000 and bovine albumin have been used to define the contribution of exogenous and endogenous effects to the gamma-radiation-induced damage in aqueous buffered suspensions of Bacillus pumilus spores. The results indicate that this damage in the bacterial spore is predominantly endogenous both in the presence of 1 atmosphere of oxygen, and in anoxia. (author)

Study of anti-oxidation and scavenging effects on free radicals of quercetin

International Nuclear Information System (INIS)

Wang Chongdao; Qiang Yizhong; Lao Qinhua; Shao Yuan

1999-01-01

The effects of Quercetin on the contents of lipid peroxides (LPO) in the mice caused by γ-whole-body irradiation by method of the modified spectrophotometry of TBA, and the scavenging effects of Quercetin on the free radicals of DNA induced by radiation exposure by means of ESR technique were investigated. The results demonstrates that Quercetin has a good anti-oxidation effect and is very effective in scavenging of free radicals

ESR-ENDOR study of x-irradiated single crystals of α.D.glucopyranose and α-methyl.D.glucopyranoside; environmental effects upon radiation and free radical chemistry in carbohydrate model systems

International Nuclear Information System (INIS)

Madden, K.P.

1980-01-01

Single crystals of x-irradiated α-D-glucopyranose (αGlu) and α-methyl-D-glucopyranoside (αMeGlu) were studied using electron spin resonance and electron nuclear double resonance spectroscopy, to determine products and reaction mechanisms in carbohydrate radiation and free-radical chemistry. Four free-radical products were identified in αMeGlu single crystals irradiated and studied at 77K. Irradiation and observation at 12K produced yet another species. Four free radicals were identified in αGlu single crystals irradiated and observed at 12K and 77K. Free radical reaction in αGlu and αMeGlu were induced by slowly warming crystals irradiated at 77K until conversion occurred. Environmental influences upon these free-radical reaction mechanisms are discussed. The results from previous work on irradiated aqueous glasses of αGlu is briefly reviewed, and compared to those obtained from the single crystal system

Efficacy of Royal Jelly in Modulating Radiation-Induced Liver Damage in Rats Subjected to Low Level of Gamma Radiation

International Nuclear Information System (INIS)

Ibrahim, N.K.

2010-01-01

Royal Jelly (RJ) is bee product, rich in proteins, vitamins, enzymes, minerals, hormones (trace elements of testosterone), lipids, glucides, niacin, pantothenic acid, biotin, inositol and folic acid, which may be beneficial in neutralizing the free oxygen radicals. The present study was carried out evaluate the radio-protective effect of Royal Jelly exposure of male Swiss albino rats to 1 Gy for 5 times day post day. Royal jelly was supplemented by gavage to rats at a dose of 150 mg/ kg body wt/ day for successive 10 days through exposure to gamma radiation 1 Gy x 5 time day post day. The dose of royal jelly is equivalent to daily human nutritional supplementation quantity. The result revealed that whole body gamma-irradiation of rats produced significant decrease in plasma total protein, albumin and globulin contents and significant increase in plasma alanine transaminase (ALT) and aspartate transaminase (AST) activity. However, plasma testosterone significantly decrease and follicle-stimulating hormone (FSH) and luteinising hormone (LH) significantly increased. Cholesterol (TC), triacyleglycerol (TAC), superoxide dismutase (SOD) and glutathione per oxidise (GSHPx) decreased whereas, malondialdehde (MDA) increased. Oral administration of the RJ exerted a noticeable amelioration of the radiation induced hormonal and biochemical changes according to the results of the present study. It could be concluded that RJ possess anti-oxidative potential that may protect the liver against ?-radiation induced acute oxidative toxicity. This protective effect might be mediated, at least in part, by the limitation of culprit free radicals and the amelioration of oxidative stress and also due to the synergistic relationship between the natural components found in RJ

Radiation-induced apoptosis of neural precursors cell cultures: early modulation of the response mediated by reactive oxygen and nitrogen species (ROS/RNS)

Energy Technology Data Exchange (ETDEWEB)

Gisone, P.; Dubner, D.; Robello, E.; Michelin, S.; Perez, M. R.

2004-07-01

Apoptosis, the typical mode of radiation-induced cell death in developing Central Nervous System (CNS), is closely related with the oxidative status. Enhanced radiation-induced generation of ROS/RNS has been observed after exposures to low radiation doses leading to cellular amplification of signal transduction and further molecular and cellular radiation-responses. Moreover Nitric oxide (NO) and hydroxyl radical are implicated in dopaminergic neurotoxicity in different parading. This study is an attempt to address the participation of radiation-induced free radicals production, the contribution of endogenous NO generation, and the excitonic pathway, in the radiation-induced apoptosis of neural cortical precursors. Cortical cells obtained from at 17 gestational day (gd) were irradiated with doses from 0,2 Gy to 2 Gy at a dose-rate of 0.3 Gy/m. A significant decrease of Luminol-dependent Chemiluminescence was evident 30 m after irradiation reaching basal levels at 120 m follow for a tendency to increasing values Incubations with Superoxide Dismatuse (SOD) decreased significantly the chemiluminescence in irradiated samples NO content estimated by measuring the stable products NO{sub 2} and NO{sub 3} released to the culture medium in the same period, has shown a time-dependent accumulation from 1 h post-irradiation. the apoptosis, determined 24 h post-irradiation by flow cytometry, morphology and DNA fragmentation revealed a dose-effect relationship with significant differences from 0.4 Gy. The samples pre-treated with 10 mM of N-acetyl cysteine (NAC) a precursor of intracellular GSH synthesis, shown a significant decrease of the apoptosis. Apoptosis was significantly increased in irradiated cells after inhibition of nitric oxide synthase (NOS) byL-NAME. We conclude that ROS/RNS play a pivotal role in the early signaling pathways leading to a radiation-induced cell death. (Author) 40 refs.

Radiation-induced apoptosis of neural precursors cell cultures: early modulation of the response mediated by reactive oxygen and nitrogen species (ROS/RNS)

International Nuclear Information System (INIS)

Gisone, P.; Dubner, D.; Robello, E.; Michelin, S.; Perez, M. R.

2004-01-01

Apoptosis, the typical mode of radiation-induced cell death in developing Central Nervous System (CNS), is closely related with the oxidative status. Enhanced radiation-induced generation of ROS/RNS has been observed after exposures to low radiation doses leading to cellular amplification of signal transduction and further molecular and cellular radiation-responses. Moreover Nitric oxide (NO) and hydroxyl radical are implicated in dopaminergic neurotoxicity in different parading. This study is an attempt to address the participation of radiation-induced free radicals production, the contribution of endogenous NO generation, and the excitonic pathway, in the radiation-induced apoptosis of neural cortical precursors. Cortical cells obtained from at 17 gestational day (gd) were irradiated with doses from 0,2 Gy to 2 Gy at a dose-rate of 0.3 Gy/m. A significant decrease of Luminol-dependent Chemiluminescence was evident 30 m after irradiation reaching basal levels at 120 m follow for a tendency to increasing values Incubations with Superoxide Dismatuse (SOD) decreased significantly the chemiluminescence in irradiated samples NO content estimated by measuring the stable products NO 2 and NO 3 released to the culture medium in the same period, has shown a time-dependent accumulation from 1 h post-irradiation. the apoptosis, determined 24 h post-irradiation by flow cytometry, morphology and DNA fragmentation revealed a dose-effect relationship with significant differences from 0.4 Gy. The samples pre-treated with 10 mM of N-acetyl cysteine (NAC) a precursor of intracellular GSH synthesis, shown a significant decrease of the apoptosis. Apoptosis was significantly increased in irradiated cells after inhibition of nitric oxide synthase (NOS) byL-NAME. We conclude that ROS/RNS play a pivotal role in the early signaling pathways leading to a radiation-induced cell death. (Author) 40 refs

Radiation-induced free radicals in DNA studied by electron paramagnetic resonance

International Nuclear Information System (INIS)

Graeslund, A.

1974-01-01

Radiation biology aims at an understanding of the effects of radiation on biological material. The studied systems may vary in complexity and size from a whole organism to the molecular constituents of a cell. The observed effects are accordingly varied, from visible somatic effects on the organism to physico-chemical molecular changes. Radiation biophysics may be considered as a specialized branch of radiation biology, dealing with physical aspects of radiation damage, particularly at a molecular or sub-cellular level. The work to be presented here is in the field of radiation biophysics, and concerns physical studies of radiation effects on deoxyribonucleic acid, DNA, the hereditary substance of all living organisms. (author)

Characterization of plasma-induced cell membrane permeabilization: focus on OH radical distribution

International Nuclear Information System (INIS)

Sasaki, Shota; Honda, Ryosuke; Hokari, Yutaro; Takashima, Keisuke; Kaneko, Toshiro; Kanzaki, Makoto

2016-01-01

Non-equilibrium atmospheric-pressure plasma (APP) is used medically for plasma-induced cell permeabilization. However, how plasma irradiation specifically triggers permeabilization remains unclear. In an attempt to identify the dominant factor( s ), the distribution of plasma-produced reactive species was investigated, primarily focusing on OH radicals. A stronger plasma discharge, which produced more OH radicals in the gas phase, also produced more OH radicals in the liquid phase (OH aq ), enhancing the cell membrane permeability. In addition, plasma irradiation-induced enhancement of cell membrane permeability decreased markedly with increased solution thickness (<1 mm), and the plasma-produced OH aq decayed in solution (diffusion length on the order of several hundred micrometers). Furthermore, the horizontally center-localized distribution of OH aq corresponded with the distribution of the permeabilized cells by plasma irradiation, while the overall plasma-produced oxidizing species in solution (detected by iodine-starch reaction) exhibited a doughnut-shaped horizontal distribution. These results suggest that OH aq, among the plasma-produced oxidizing species, represents the dominant factor in plasma-induced cell permeabilization. These results enhance the current understanding of the mechanism of APP as a cell-permeabilization tool. (paper)

Characterization of 60 Co y-radiation induced radical products of antipyrine by means of high performance liquid chromatography, mass spectrometry, capillary zone electrophoresis, micellar electrokinetic capillary chromatography and nuclear magnetic resonance spectrometry

NARCIS (Netherlands)

Coolen, S.A.J.; Everaerts, F.M.; Huf, F.A.

1997-01-01

Monitoring the amount of oxidative damage, caused by free radicals, is a major problem in free radical and aging research. Antipyrine is proposed as an exogenous marker for the biomolecular monitoring of oxidative stress. In this paper the characterization of the 60Co γ-radiation products of

Characterization of 60Co gamma-radiation induced radical products of antipyrine by means of high-performance liquid chromatography, mass spectrometry, capillary zone electrophoresis, micellar electrokinetic capillary chromatography and nuclear magnetic resonance spectrometry

NARCIS (Netherlands)

Coolen, S.A.J.; Everaerts, F.M.; Huf, F.A.

1997-01-01

Monitoring the amount of oxidative damage, caused by free radicals, is a major problem in free radical and aging research. Antipyrine is proposed as an exogenous marker for the biomolecular monitoring of oxidative stress. In this paper the characterization of the 60Co ¿-radiation products of

Natural Products Garlic Oil and Vitamin E, Control Radiation Induced Disorders of Lipid and Carbohydrate Metabolism in Rats

International Nuclear Information System (INIS)

Ragab, E.A.; Ashry, O.M.

2004-01-01

Increased level of lipid peroxides in various tissues of irraiated animals, may play a crucial role in determining the pathogenesis of radiation exposure. Many of the damaging effects of ionizing radiation are mediated by reactive free radicals. The efficacy of oral treatment of rats with garlic oil (100 mg/kg body weight) for ten days and intraperitoneal administration of vitamin E (100mg/kg body wt.) two hours before whole body gamma irradiation (7Gy), was examine on certain biochemical parameters. The data obtained revealed that, radiation exposure caused increase in serum malondialdehyde level (indicating lipid peroxiation accompanied by increase in serum total lipid, trigacylglycerol, cholesterol an low density lipoprotein with significant decrease in high density lipoprotein. Radiation exposure also induced significant elevation in serum glucose level, liver glycogen and liver glucose 6-phosphatase activity level. Administration of the natural product (garlic oil) and /or vitamin E ameliorates the radiation inuced disturbances in lipid and carbohydrate metabolism. The study confirmed the beneficial role of the used antioxidative agents as recommended radioprotectors due to their ability of scavenging free radicals produced by ionizing radiation or oxidative stress

Peroxy Radical Measurements via Laser Induced Fluorescence

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Trawny, Katrin; Tatum Ernest, Cheryl; Novelli, Anna; Elste, Thomas; Plaß-Dülmer, Christian; Rudolf, Markus; Martinez, Monica; Harder, Hartwig; Lelieveld, Jos

2013-04-01

We present a newly built Laser Induced Fluorescence (LIF) system to measure the sum of all peroxy radicals (RO2) utilizing chemical conversion to OH. This instrument operates in two different modes: the ROx mode (sum of OH, HO2, and RO2) and the HOx mode (sum of OH and HO2). The HOx mode is used to derive the RO2 data from the ROx measurements. A model approach was used during instrumental development to identify the key parameters needed for the conversion process in front of the detection area and to optimize sensitivity. The instrument was then carefully characterized in various lab experiments, where it could be shown that the wall losses for HO2 are negligible and that nearly all HO2 is converted to OH in front of the detection zone. The pressure and temperature dependencies were also analyzed and assured that the instrument does not show any photolytical interference. As the instrument is calibrated with only one kind of peroxy radicals it was very important that the differences in sensitivity for different peroxy radicals are acceptable. Lab experiments as well as first results from the HOPE 2012 intensive field campaign, which took place in summer 2012 at the Global Atmosphere Watch (GAW) station of the German Weather Service, will be discussed.

EPR persistence measurements of UV-induced melanin free radicals in whole skin

International Nuclear Information System (INIS)

Collins, B.; Poehler, T.O.; Bryden, W.A.

1995-01-01

Electron paramagnetic resonance is used to detect the formation of free radicals caused by exposure to ultraviolet radiation in chemically untreated rabbit skin. A fast jump in EPR signal level, occurring over a few seconds, is observed immediately after a skin sample is exposed to UV. This is followed by a slower increase toward an elevated steady-state signal over a period of hours as the skin is continuously exposed to a UV light source. Upon cessation of UV light exposure, EPR signal levels undergo an abrupt drop followed by a slower decay toward natural levels. Elevated free radical concentrations following UV exposure are found to persist for several hours in whole skin. These results are consistent with time resolved EPR measurements of photoinduced radicals in various natural melanins. (Author)

Modulation of ionizing radiation induced oxidative imbalance by semi-fractionated extract of Piper betle: an in vitro and in vivo assessment.

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Verma, Savita; Gupta, Manju Lata; Dutta, Ajaswrata; Sankhwar, Sanghmitra; Shukla, Sandeep Kumar; Flora, Swaran J S

2010-01-01

The study was planned to evaluate modulatory effect of aqueous extract of Piper betle leaf (PBL) on ionizing radiation mediated oxidative stress leading to normal tissues damage during radiotherapy and other radiation exposures. The total polyphenols and flavonoids known as free radical scavenger (chelators) were measured in the extract. To ascertain antioxidant potential of PBL extract we studied free radical scavenging, metal chelation, reducing power, lipid peroxidation inhibition and ferric reducing antioxidant properties (FRAP) using in vitro assays. Mice were exposed to varied radiation doses administered with the same extract prior to irradiation to confirm its oxidative stress minimizing efficacy by evaluating ferric reducing ability of plasma, reduced glutathione, lipid peroxidation and micro-nuclei frequency. PBL extract was effective in scavenging DPPH (up to 92% at 100 microg/ml) and superoxide radicals (up to 95% at 80 microg/ml), chelated metal ions (up to 83% at 50 microg/ml) and inhibited lipid peroxidation (up to 55.65% at 500 microg/ml) in a dose dependant manner using in vitro model. Oral administration of PBL extract (225 mg/kg body weight) 1 hr before irradiation in mice significantly enhanced (p < 0.01) radiation abated antioxidant potential of plasma and GSH level in all the observed organs. The treatment with extract effectively lowered the radiation induced lipid peroxidation at 24 hrs in all the selected organs with maximum inhibition in thymus (p < 0.01). After 48 hrs, lipid peroxidation was maximally inhibited in the group treated with the extract. Frequency of radiation induced micronucleated cells declined significantly (34.78%, p < 0.01) at 24 hrs post-irradiation interval by PBL extract administration. The results suggest that PBL extract has high antioxidant potential and relatively non-toxic and thus could be assertively used to mitigate radiotherapy inflicted normal tissues damage and also injuries caused by moderate doses of

Nicaraven attenuates radiation-induced injury in hematopoietic stem/progenitor cells in mice.

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Miho Kawakatsu

Full Text Available Nicaraven, a chemically synthesized hydroxyl radical-specific scavenger, has been demonstrated to protect against ischemia-reperfusion injury in various organs. We investigated whether nicaraven can attenuate radiation-induced injury in hematopoietic stem/progenitor cells, which is the conmen complication of radiotherapy and one of the major causes of death in sub-acute phase after accidental exposure to high dose radiation. C57BL/6 mice were exposed to 1 Gy γ-ray radiation daily for 5 days in succession (a total of 5 Gy, and given nicaraven or a placebo after each exposure. The mice were sacrificed 2 days after the last radiation treatment, and the protective effects and relevant mechanisms of nicaraven in hematopoietic stem/progenitor cells with radiation-induced damage were investigated by ex vivo examination. We found that post-radiation administration of nicaraven significantly increased the number, improved the colony-forming capacity, and decreased the DNA damage of hematopoietic stem/progenitor cells. The urinary levels of 8-oxo-2'-deoxyguanosine, a marker of DNA oxidation, were significantly lower in mice that were given nicaraven compared with those that received a placebo treatment, although the levels of intracellular and mitochondrial reactive oxygen species in the bone marrow cells did not differ significantly between the two groups. Interestingly, compared with the placebo treatment, the administration of nicaraven significantly decreased the levels of the inflammatory cytokines IL-6 and TNF-α in the plasma of mice. Our data suggest that nicaraven effectively diminished the effects of radiation-induced injury in hematopoietic stem/progenitor cells, which is likely associated with the anti-oxidative and anti-inflammatory properties of this compound.

Radical's view of sciences

International Nuclear Information System (INIS)

Mittal, J.P.

2004-01-01

Full text: General concept in radiation biology is that free radicals are highly reactive and they can damage vital cellular molecules leading to injurious effects. However, in this talk, evidence will be presented through the techniques of electron paramagnetic resonance ( EPR ) and pulse radiolysis that free radicals can be highly selective in their reaction with the target molecules. In addition, attempts will be made to present a brief account of emerging scenario of free radical generation, identification and their involvement in radiation damage mechanisms in chemical and biological systems

Pyrimidine nucleobase radical reactivity in DNA and RNA

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Greenberg, Marc M.

2016-11-01

Nucleobase radicals are major products of the reactions between nucleic acids and hydroxyl radical, which is produced via the indirect effect of ionizing radiation. The nucleobase radicals also result from hydration of cation radicals that are produced via the direct effect of ionizing radiation. The role that nucleobase radicals play in strand scission has been investigated indirectly using ionizing radiation to generate them. More recently, the reactivity of nucleobase radicals resulting from formal hydrogen atom or hydroxyl radical addition to pyrimidines has been studied by independently generating the reactive intermediates via UV-photolysis of synthetic precursors. This approach has provided control over where the reactive intermediates are produced within biopolymers and facilitated studying their reactivity. The contributions to our understanding of pyrimidine nucleobase radical reactivity by this approach are summarized.

Free radical reactions of hematoporphyrin: a pulse radiolysis study

International Nuclear Information System (INIS)

Ahmed, Mohammed; Guleria, Apurav; Singh, Ajay K.; Sarkar, S.K.

2011-01-01

Radiation chemistry of porphyrin derivatives has been given much attention in recent years. Although till date photo dynamic therapy (PDT) with Hematoporphyrin (HP) has already proved its effectiveness in the treatment of cancer, the molecular mechanisms by which this therapy-destroys tumour cells as well as its optimal physical parameters are still not fully understood. Thus it becomes necessary to understand the interaction of different free radicals with HP. Pulse radiolysis studies have been performed to understand the interaction of different free radicals with HP. The product formation along with bleaching and presence of a number of transients makes it difficult to pin point the mode and site of free radical attack. The radiation-induced formation of various transients (HP-OH, HO - , HP + ) in aqueous solution was investigated at various pHs by pulse radiolysis technique by means of N 3 , O - and CCl 3 O 2 radicals with and without triethyl-amine, under different dose conditions. The observed intermediates are characterized by their kinetic and spectroscopic data. The absorption spectrum of each transient could be differentiated from each other by their absorption maxima, extinction coefficients and kinetics. A clear indication of product formation has also been observed by employing continuous electron pulse and the solution shows a green coloration. It is conceivable that under certain conditions, similar transients may be produced when HP is used as a sensitizer in radiation chemotherapy of cancer patients. Our study may throw some light into the breakdown mechanism of haemoglobin to BV in addition to the understanding of free radical interaction of HP. (author)

Pre-administration of safe exogenous substance minimizes radiation induced bone-marrow aplsia which may otherwise lead to hematopoietic disaster

International Nuclear Information System (INIS)

Gupta, Manju Lata; Verma, Savita; Ranjan, Rajiv

2014-01-01

Radiation induces injuries to biological system primarily by producing free radicals and also by directly interacting with cellular entities. In irradiated animals hematopoietic system gets severely affected leading to inactive microenvironment, damaged blood vessels and non functional endothelial cells of the marrow. Vascular damage inhibits the efficacy of stem cells to proliferate and differentiate. Release of pro-inflammatory cytokines and activation of fibroblast further contribute to the development of radiation-induced fibrosis. Various findings have revealed the occurrence of radiation induced aplasia and vascular damage cause large number of RBCs occupying the space and intrusion of fibrotic cells in the marrow of irradiated mice. Administration of effective radioprotective agents prior to irradiation has been amply reported for significant decline in the grade of vascular damage and inclusion of marrow fibrous tissues in these animals. In addition the formulations have also shown the presence stem cell population which is efficient to proliferate, differentiate and ultimately enrich bone marrow cellularity within 25-40 days depending on type of radiation and its dose and dose rate. Protection to bone marrow is multi-factorial phenomenon out of which inhibition of radiation induced free radical generation has been recognized as the key factor but essentially not the lone one. Protection to colony forming ability of bone marrow is also critically important which occurs mainly due to DNA protection and up-regulation of repair pathways. Preservation of microenvironment for providing stem cells to remain functional is lately reported as equally prominent factor. Our studies on a combination of two compounds of natural origin, administered to lethally irradiated animals have shown recovery in stem/precursor cells of all hematopoietic lineages. Major entities related to hematopoietic system were found nearly 90% recovered within 30 days. Current talk is focused

Effect of chlorophyllin on frequency radiation-induced of sister chromatid exchanges (SCE) and other cytogenetic events in mice bone marrow cells In Vivo

International Nuclear Information System (INIS)

Garcia Rodriguez, M.C.

1992-01-01

The effect of chlorophyllin on gamma radiation induced Sister chromatid exchanges (SCE) and on the mitotic index (IM) and average generation time was determined. Groups of mice were treated in one of the following regimens: (1) untreated, (2) treated with chlorophyllin only, (3) irradiated and (4) treated with chlorophyllin and irradiated intraperitoneal administration of chlorophyllin preceding gamma radiation exposure protected again SCE induction and diminution of IM. However, radioprotection was not reflected in the average generation time for the chlorophyllin per se acceleration the average generation time. The results suggest that, under the experimental conditions of the study the SCE and IM are caused by free radicals produced by radiation and wat the action mechanics of chlorophyllin is scavenger free radicals. (Author)

Theoretical radiative properties between states of the triplet manifold of NH radical

International Nuclear Information System (INIS)

Owono Owono, L.C.; Jaidane, N.; Ben Lakhdar, Z.

2007-12-01

Ab initio transition dipole moments between states of the triplet manifold of NH radical are presented. This enables the computation of various radiative characteristics such as Einstein coefficients, radiative lifetimes and oscillator strengths. These properties concern valence and Rydberg states as well for which spectroscopic parameters are rather scarce and sometimes inexistent. Our results show good agreement with available experimental data in comparison to other theoretical numbers reported in the literature. This helps to build confidence on the quantities for which data were not found for comparative purposes. It is expected that the present study may enhance further astrophysical and laboratory investigations. (author)

Radioprotective Effect of Achillea millefolium L Against Genotoxicity Induced by Ionizing Radiation in Human Normal Lymphocytes

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Somayeh Shahani

2015-04-01

Full Text Available The radioprotective effect of Achillea millefolium L (ACM extract was investigated against genotoxicity induced by ionizing radiation (IR in human lymphocytes. Peripheral blood samples were collected from human volunteers and incubated with the methanolic extract of ACM at different concentrations (10, 50, 100, and 200 μg/mL for 2 hours. At each dose point, the whole blood was exposed in vitro to 2.5 Gy of X-ray and then the lymphocytes were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis-blocked binucleated cell. Antioxidant capacity of the extract was determined using free radical-scavenging method. The treatment of lymphocytes with the extract showed a significant decrease in the incidence of micronuclei binucleated cells, as compared with similarly irradiated lymphocytes without any extract treatment. The maximum protection and decrease in frequency of micronuclei were observed at 200 μg/mL of ACM extract which completely protected genotoxicity induced by IR in human lymphocytes. Achillea millefolium extract exhibited concentration-dependent radical-scavenging activity on 1,1-diphenyl-2-picryl hydrazyl free radicals. These data suggest that the methanolic extract of ACM may play an important role in the protection of normal tissues against genetic damage induced by IR.

Influence of anoxia on the induction of mutations by phenylalanine radicals during gamma-irradiation of plasmid DNA in aqueous solution.

Science.gov (United States)

Kuipers, Gitta K; Slotman, Ben J; Reitsma-Wijker, Carola A; van Andel, Rob J; Poldervaart, Hester A; Lafleur, M Vincent M

2004-12-21

When DNA is irradiated in aqueous solution, most of the damage is inflicted by water-derived radicals. This is called the indirect effect of ionizing radiation. However in whole cells not only the primary formed water radicals play a role, because some cellular compounds form secondary radicals which can also damage DNA. It is known that the amino acid phenylalanine is able to react with water radicals, resulting in the production of secondary phenylalanine radicals which can damage and inactivate DNA. In a previous study the influence of the presence of phenylalanine during gamma-irradiation of DNA in aqueous solution under oxic conditions was studied. Under anoxic irradiation conditions different amounts and types of reactive water-derived radicals are formed compared to oxic conditions and also different phenylalanine radicals are formed. Therefore, this study examines the influence of the presence of phenylalanine under anoxic conditions on the gamma-radiation-induced mutation spectrum. The results indicate that phenylalanine radicals are damaging to DNA, but less effective compared to primary water radicals. On the mutational level, in the presence of phenylalanine radicals under anoxic conditions, the amount of mutations on G:C base pairs was significantly decreased as compared to oxic conditions. Furthermore, the results of this study indicate that nucleotide excision repair is involved in repair of both inactivating and mutagenic damage induced by phenylalanine radicals under anoxic conditions.

Mechanism of antioxidant interaction on polymer oxidation by thermal and radiation ageing

International Nuclear Information System (INIS)

Seguchi, Tadao; Tamura, Kiyotoshi; Shimada, Akihiko; Sugimoto, Masaki; Kudoh, Hisaaki

2012-01-01

The mechanism of polymer oxidation by radiation and thermal ageing was investigated for the life evaluation of cables installed in radiation environments. The antioxidant as a stabilizer was very effective for thermal oxidation with a small content in polymers, but was not effective for radiation oxidation. The ionizing radiation induced the oxidation to result in chain scission even at low temperature, because the free radicals were produced and the antioxidant could not stop the oxidation of radicals with the chain scission. A new mechanism of antioxidant effect for polymer oxidation was proposed. The effect of antioxidant was not the termination of free radicals in polymer chains such as peroxy radicals, but was the depression of initial radical formation in polymer chains by thermal activation. The antioxidant molecule was assumed to delocalize the activated energy in polymer chains by the Boltzmann statics (distribution) to result in decrease in the probability of radical formation at a given temperature. The interaction distance (delocalization volume) by one antioxidant molecule was estimated to be 5–10 nm by the radius of sphere in polymer matrix, though the value would depend on the chemical structure of antioxidant. - Highlights: ► Interaction of antioxidant on polymer oxidation is discussed for thermal and radiation ageings. ► Antioxidant is very effective for thermal oxidation, but not for radiation induced oxidation. ► Interaction of antioxidant is not the termination reaction of radicals on polymers. ► Antioxidant is supposed to reduce the provability of polymer radical formation by thermal activation. ► Mechanism of polymer oxidation may not be chain reaction via peroxy radical and hydro-peroxide.

The chemistry of separations ligand degradation by organic radical cations

International Nuclear Information System (INIS)

Mezyk, S.P.; Horne, G.P.; Mincher, B.J.; Zalupski, P.R.; Cook, A.R.; Wishart, J.F.

2016-01-01

Solvent based extractions of used nuclear fuel use designer ligands in an organic phase extracting ligand complexed metal ions from an acidic aqueous phase. These extractions will be performed in highly radioactive environments, and the radiation chemistry of all these complexing agents and their diluents will play a major role in determining extraction efficiency, separation factors, and solvent-recycle longevity. Although there has been considerable effort in investigating ligand damage occurring in acidic water radiolysis conditions, only minimal fundamental kinetic and mechanistic data has been reported for the degradation of extraction ligands in the organic phase. Extraction solvent phases typically use normal alkanes such as dodecane, TPH, and kerosene as diluents. The radiolysis of such diluents produce a mixture of radical cations (R"."+), carbon-centered radicals (R".), solvated electrons, and molecular products such as hydrogen. Typically, the radical species will preferentially react with the dissolved oxygen present to produce relatively inert peroxyl radicals. This isolates the alkane radical cation species, R"."+ as the major radiolytically-induced organic species that can react with, and degrade, extraction agents in this phase. Here we report on our recent studies of organic radical cation reactions with 2 ligands: CMPO and TODGA. Elucidating these parameters, and combining them with the known acidic aqueous phase chemistry, will allow a full, fundamental, understanding of the impact of radiation on solvent extraction based separation processes to be achieved. (authors)

Synchrotron radiation induced direct photo-etching and surface modification of PTFE

International Nuclear Information System (INIS)

Oshima, Akihiro; Washio, Masakazu

2003-01-01

In the first part of this article, we have described and discussed the measurement results of etching rates by direct photo-etching using Synchrotron Radiation (SR) for various kind of crosslinked PTFEs, which were prepared by different crosslinking doses, comparing with the non-crosslinked PTFE. It has been found that the etching rates obtained for crosslinked PTFE were much larger than that of non-crosslinked one. These results are not described by simple consideration such as the G values of main chain scission. We propose that the etching rates should be discussed by the complex mechanism through at least two different steps such as polymer decomposition and fragment desorption. In the second part of the article, we have described and discussed the abnormal reaction induced at the surface region after the SR etching for non-crosslinked PTFE. Through the measurements using DSC and solid state 19 F-NMR, we have confirmed the crosslinking reaction of PTFE even in solid state PTFE. This should be induced by the very high density radical formation in very thin area of PTFE films by SR radiation. (author)

Radical production in biological systems

International Nuclear Information System (INIS)

Johnson, J.R.; Akabani, G.

1994-10-01

This paper describes our effort to develop a metric for radiation exposure that is more fundamental than adsorbed dose and upon which a metric for exposure to chemicals could be based. This metric is based on the production of radicals by the two agents. Radicals produced by radiation in biological systems commonly assumed to be the same as those produced in water despite the presence of a variety of complex molecules. This may explain why the extensive efforts to describe the relationship between energy deposition (track structure) and molecular damage to DNA, based on the spectrum of radicals produced, have not been successful in explaining simple biological effects such as cell killing. Current models assume that DNA and its basic elements are immersed in water-like media and only model the production and diffusion of water-based radicals and their interaction with DNA structures; these models lack the cross sections associated with each macro-component of DNA and only treat water-based radicals. It has been found that such models are not realistic because DNA is not immersed in pure water. A computer code capable of simulating electron tracks, low-energy electrons, energy deposition in small molecules, and radical production and diffusion in water like media has been developed. This code is still in at a primitive stage and development is continuing. It is being used to study radical production by radiation, and radical diffusion and interactions in simple molecular systems following their production. We are extending the code to radical production by chemicals to complement our PBPK modeling efforts. It therefore has been developed primarily for use with radionuclides that are in biological materials, and not for radiation fields

Electronic Paramagnetic Resonance (EPR) of free radicals induced by X-rays in pyrene

International Nuclear Information System (INIS)

Moya Partiti, C.S. de.

1982-01-01

Pyrene single crystals C 16 H 10 , irradiated by X-rays, at room temperature, were studied by EPR technique, to determine free radicals formed by radiation. The angular dependence of EPR spectra was explained by the presence of two kinds of radicals with an aditional hydrogen: 2-H 2 pyrene and 3-H 2 pyrene. It was studied the isothermic decay of the EPR signal and two typical values for the activation energy were found = (1,9+-0,1) eV and (1,93+-0,03) eV. (author) [pt

Protective effect of zingerone, a dietary compound against radiation induced damage

International Nuclear Information System (INIS)

Satish Rao, B.S.; Rao, Nageshwar

2012-01-01

, scavenging of radiation-induced free radicals and by the suppression of lipid peroxidation as well as oxidative stress. (author)

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

Science.gov (United States)

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

2016-08-01

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

Effects of ionising radiation on isolated and cellular DNA

International Nuclear Information System (INIS)

Cadet, J.; Artignan, X.; Berger, M.; Douki, T.; Gromova, M.; Polverelli, M.; Ravanat, J.L.

1997-01-01

In the present survey, emphasis has been placed on mechanistic aspects of the radiation-induced decomposition of the base moities of DNA and model compounds. An almost complete description of the radical reactions mediated by both OH radicals (indirect effects) and one-electron oxidation (direct effects) is now possible for guanine compounds in aerated aqueous solution. In addition, the results of a comparison of a targeted assay (high performance liquid chromatography-electrochemical method) and a non specific method ('comet assay') for monitoring radiation-induced DNA damage within human cells are reported. (authors)

The influence of non-radiation induced ESR background signal from paraffin-alanine probes for dosimetry in the radiotherapy dose range

International Nuclear Information System (INIS)

Wieser, A.; Lettau, C.; Fill, U.; Regulla, D.F.

1993-01-01

The yield of radicals induced by ionizing radiation in the amino acid alanine and its quantification by ESR spectroscopy has proven excellent reproducibility. Those radicals trapped in the crystal lattice are prevented from recombination providing a thermally very stable system. This allows alanine to be applied as a transfer dosemeter. With paraffin-alanine probes ESR dosimetry can be performed with a standard deviation of ± 0.5% in the dose range from 20 Gy up to 100 kGy. At 1 Gy dose level the error increases to ± 6%. This dose level is three orders of magnitude higher than the calculated detection threshold for alanine with modern X-band ESR spectrometers. It was found that the poor standard deviation at the 1 Gy dose level, is not mainly produced by a bad signal-to-noise ratio but by a variable non-radiation induced ESR background signal from the alanine probes within a batch. In the present study the main sources of error for ESR dosimetry in the dose range below 20 Gy were analyzed. The influences of the production process, UV light and humidity upon the ESR background signal from paraffin-alanine probes were investigated. Measurements are shown indicating a second stable structure of the alanine radical at room temperature. (author)

Protective Effect of Anthocyanins from Lingonberry on Radiation-induced Damages

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Shuang-Qi Tian

2012-12-01

Full Text Available There is a growing concern about the serious harm of radioactive materials, which are widely used in energy production, scientific research, medicine, industry and other areas. In recent years, owing to the great side effects of anti-radiation drugs, research on the radiation protectants has gradually expanded from the previous chemicals to the use of natural anti-radiation drugs and functional foods. Some reports have confirmed that anthocyanins are good antioxidants, which can effectively eliminate free radicals, but studies on the immunoregulatory and anti-radiation effects of anthocyanins from lingonberry (ALB are less reported. In this experiment, mice were given orally once daily for 14 consecutive days before exposure to 6 Gy of gamma-radiation and were sacrificed on the 7th day post-irradiation. The results showed that the selected dose of extract did not lead to acute toxicity in mice; while groups given anthocyanins orally were significantly better than radiation control group according to blood analysis; pretreatment of anthocyanins significantly (p < 0.05 enhanced the thymus and spleen indices and spleen cell survival compared to the irradiation control group. Pretreatment with anthocyanins before irradiation significantly reduced the numbers of micronuclei (MN in bone marrow polychromatic erythrocytes (PCEs. These findings indicate that anthocyanins have immunostimulatory potential against immunosuppression induced by the radiation.

Room temperature Q-band electron magnetic resonance study of radicals in X-ray-irradiated L-threonine single crystals

International Nuclear Information System (INIS)

Vanhaelewyn, Gauthier; Vrielinck, Henk; Callens, Freddy

2014-01-01

In the past, decennia radiation-induced radicals were successfully identified by electron magnetic resonance (EMR) in several solid-state amino acids and sugars. The authors present a room temperature (RT) EMR study of the stable radicals produced by X-ray-irradiation in the amino acid L-threonine (CH 3 CH(OH)CH(NH3 + )COO - ). Its chemical structure is similar to that of the well-known dosimetric material L-alanine (CH 3 CH(NH3 + )COO - ), and radiation defects in L-threonine may straightforwardly be compared with the extensively studied L-alanine radicals. The hyperfine coupling tensors of three different radicals were determined at RT using electron nuclear double resonance. These results indicate that the two most abundant radicals share the same basic structure CH 3 .C(OH)CH(NH3 + )COO - , obtained by H-abstraction, but are stabilised in slightly different conformations. The third radical is most probably obtained by deamination (CH 3 CH(OH).CHCOO - ), similar in structure to the stable alanine radical. (authors)

Radiation-chemical transformations of coumarins in ethanolic solutions

International Nuclear Information System (INIS)

Samovich, S.N.; Brinkevich, S.D.; Edimecheva, I.P.; Shadyro, O.I.

2014-01-01

Effects of coumarin and its derivatives on product formation during radiolysis of deaerated and oxygenated ethanol were investigated. The data obtained in this study indicate that coumarin, 4-hydroxycoumarin and warfarin effectively oxidized α-hydroxyethyl radicals (α-HER), while esculetin and fraxetin predominantly reduced the above named intermediates. Coumarin, esculetin and fraxetin were able to add α-HER to the double carbon–carbon bond of the pyrone ring to form stable products with molecular masses exceeding those of the starting molecules. Coumarin, warfarin, esculetin and fraxetin were shown to display antioxidant activity during radiation-induced oxidation of ethanol. - Highlights: • Coumarin, 4-hydroxycoumarin and warfarin oxidize α-hydroxyethyl radicals. • Esculetin and fraxetin predominantly reduce α-hydroxyethyl radicals. • Coumarins add α-hydroxyethyl radicals to the C=C bonds of the pyrone ring. • Coumarins display antioxidant activity on radiation-induced oxidation of ethanol

Radiation-induced thermoacoustic imaging

International Nuclear Information System (INIS)

Bowen, T.

1984-01-01

This invention provides a new technique for obtaining information non-invasively on the composition and structures of a material or body by detecting radiation-induced thermoacoustic image features. This is accomplished by utilizing the acoustic wave generated by sudden thermal stress. The sudden thermal stress is induced by a pulse of radiation which deposits energy causing a rapid, but very small, rise of temperature (typically, ΔT approximately 10sup(-6) - 10sup(-5) deg C). The radiation may be ionizing radiation, such as high energy electrons, photons (x-rays), neutrons, or other charged particles or it may be non-ionizing radiation, such as R.F. and microwave electromagnetic radiation and ultrasonic radiation. The choice of radiation depends on the nature of the body to be imaged and the type of information desired

Radiation-induced emulsion polymerization of tetrafluoroethylene

International Nuclear Information System (INIS)

Suwa, Takeshi

1979-10-01

The radiation-induced emulsifier-free emulsion polymerization of tetrafluoroethylene (TFE) has been studied at initial pressure 2 - 25 kg/cm 2 and temperature 30 0 - 110 0 C for dose rate 0.57 x 10 4 - 3.0 x 10 4 rad/hr. Polytetrafluoroethylene (PTFE), a hydrophobic polymer, forms as a stable latex in the absence of an emulsifier. Stability of the latex is governed by the dose rate/TFE pressure ratio; it increases with sufficient TFE monomer. PTFE particles produced in this polymerization system are stable due to the carboxyl end groups and adsorption of OH - and HF on the particles. PTFE latex of molecular weight higher than 2 x 10 7 is obtained by addition of a radical scavenger such as hydroquinone. The molecular weight of PTFE can be measured from the heat of crystallization conveniently with high reliability, which was found in the course of study on the melting and crystallization behavior. (author)

Radiation chemistry of carbohydrates and of the sugar moiety in DNA

International Nuclear Information System (INIS)

Sonntag, C. von

1979-01-01

The free radical chemistry of carbohydrates as studied by radiation techniques is briefly reviewed. In aqueous solutions OH radicals and H atoms abstract carbon-bound H atoms to give the primary carbohydrate radicals which can undergo a number of elimination and rearrangement reactions leading to secondary carbohydrate radicals. Oxygen can suppress these elimination and rearrangement reactions by converting the primary carbohydrate radicals into the corresponding peroxyl radicals. The reactions leading to the observed products are discussed. In the solid state a few carbohydrates show radiation-induced chain reactions which are of preparative interest. Hydroxyl radical attack at the sugar moiety of DNA eventually leads to DNA strand breaks and to alkali-labile sites. (Auth.)

Enhancement of alpha particles-induced cell transformation by oxygen free radicals and tumor necrosis factor released from phagocytes

International Nuclear Information System (INIS)

Gong Yifen; Guo Renfeng; Zhu Maoxiang; Shou Jiang; Ge Guixiu; Yang Zhihua; Hieber, L.; Peters, K.; Schippel, C.

1997-01-01

To illustrate the role of several endogenous factors released from phagocytes under chronic inflammation in radiation-induced cancer. C 3 T 10 T 1/2 and SHE cells were used as targets, and 238 Pu alpha source was used in alpha irradiation. The enhancement of TF in alpha particles-induced cell transformation by PMA-stimulated human blood and zymosan-stimulated U-937 cells was studied using formation of transformed foci. Transformation frequency (TF) of C 3 H 10 T 1/2 cells exposed to alpha particles of 0.5 Gy increased 2.1 and 2.8 fold by PMA-and PMA-stimulated neutrophils, respectively. TF of irradiated SHE cells at a dose of 0.5 Gy increased 12 fold by the addition of the supernatant of macrophage-like U-937 cell line. It was shown that TF of irradiated SHE cells at above dose increased 8 fold by the supernatant treated with anti-TNF-α could be subcultured continuously in vitro. The cells at 40 th passage and two lines of monoclone cells have the ability to develop malignant tumors in nude mice. The overdose of free radicals and TNF-α released from neutrophils and macrophages have played an important role in low dose radiation-induced cancer

Electron spin resonance study on γ-ray-induced ethyl radical in ethane hydrate

International Nuclear Information System (INIS)

Takeya, Kei; Nango, Kouhei; Sugahara, Takeshi; Ohgaki, Kazunari; Tani, Atsushi; Ito, Hironori; Okada, Michio; Kasai, Toshio

2007-01-01

Electron spin resonance (ESR) studies have been performed to investigate radicals induced in ethane hydrate irradiated by γ-rays at 77K. Two ESR spectra are observed and identified as the induced ethyl radical (g=2.0031±0.0005, A α sub(perpendicular)=2.2±0.1mT, A α sub(parallel)=2.5±0.1mT, A β =2.7±0.1mT) and induced atomic hydrogen (g=2.0026±0.0005, A=50.5±0.1mT). From the results of ESR analysis and gas mass spectroscopy, it is concluded that the ethyl radical decays into butane by dimerization in the first-order reaction in the temperature region of 250-265K. The activation energy of the decay reaction is 73.1±6.3kJ/mol, which is near the dissociation enthalpy change of ethane hydrate to liquid water and gaseous ethane. This finding implies that ethane hydrate does not dissociate into ice but supercooled water in the present temperature region, similar to the dissociation of methane hydrate in our previous study. (author)

Melatonin as Protection Against Radiation Injury

DEFF Research Database (Denmark)

Zetner, D.; Andersen, L. P H; Rosenberg, J.

2016-01-01

Introduction: Radiation is widely used in the treatment of various cancers and in radiological imaging procedures. Ionizing radiation causes adverse effects, leading to decreased quality of life in patients, by releasing free radicals that cause oxidative stress and tissue damage. The sleep......-hormone melatonin is a free radical scavenger, and induces several anti-oxidative enzymes. This review investigates the scientific literature on the protective effects of melatonin against exposure to ionizing radiation, and discusses the clinical potential of melatonin as prophylactic treatment against ionizing...... and protected against radiation enteritis. These protective effects were only documented when melatonin was administered prior to exposure to ionizing radiation. Discussion: This review documents that melatonin effectively protects animals against injury to healthy tissues from ionizing radiation. However...

Influence of the irradiation temperature on the free-radical response of alanine

International Nuclear Information System (INIS)

Wieser, A.; Siegele, R.; Regulla, D.F.

1989-01-01

GSF operates the only IAEA high-level dosimetry reference laboratory and, as a joint project with the IAEA, the International Dose Assurance Service (IDAS). Dosimetry is based on long-lived free radicals in organic alanine induced by ionizing radiation and readout by ESR spectroscopy. The thermal time response of the radical concentration in alanine is fairly constant after irradiation provided that the alanine samples are stored at temperatures below 50 0 C. By contrast, a positive temperature coefficient had earlier been found at GSF for the production rate of alanine radicals, for irradiation temperatures between 0 and 50 0 C. This effect has to be considered for reference dosimetry in radiation processing. Radiation processing is also of interest at irradiation temperatures below 0 0 C. The present study describes experiments on the influence of irradiation temperatures between +50 and -100 0 C. Comparison is made between the present and earlier results, in the overlapping temperature range. An empirical function is proposed for the temperature coefficient based on the experimental data. (author)

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

International Nuclear Information System (INIS)

Shimizu, Takashi; Ichikawa, Tsuneki

2005-01-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon γ-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M n R 1 COOCH(C 6 H 5 )R 2 M n +e - ->M n R 1 COO - + · CH(C 6 H 5 )R 2 M n . The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching

UV and ionizing radiations induced DNA damage, differences and similarities

Science.gov (United States)

Ravanat, Jean-Luc; Douki, Thierry

2016-11-01

Both UV and ionizing radiations damage DNA. Two main mechanisms, so-called direct and indirect pathways, are involved in the degradation of DNA induced by ionizing radiations. The direct effect of radiation corresponds to direct ionization of DNA (one electron ejection) whereas indirect effects are produced by reactive oxygen species generated through water radiolysis, including the highly reactive hydroxyl radicals, which damage DNA. UV (and visible) light damages DNA by again two distinct mechanisms. UVC and to a lesser extend UVB photons are directly absorbed by DNA bases, generating their excited states that are at the origin of the formation of pyrimidine dimers. UVA (and visible) light by interaction with endogenous or exogenous photosensitizers induce the formation of DNA damage through photosensitization reactions. The excited photosensitizer is able to induce either a one-electron oxidation of DNA (type I) or to produce singlet oxygen (type II) that reacts with DNA. In addition, through an energy transfer from the excited photosensitizer to DNA bases (sometime called type III mechanism) formation of pyrimidine dimers could be produced. Interestingly it has been shown recently that pyrimidine dimers are also produced by direct absorption of UVA light by DNA, even if absorption of DNA bases at these wavelengths is very low. It should be stressed that some excited photosensitizers (such as psoralens) could add directly to DNA bases to generate adducts. The review will described the differences and similarities in terms of damage formation (structure and mechanisms) between these two physical genotoxic agents.

Radical surgical resection and high-dose intraoperative radiation therapy (HDR-IORT) in patients with recurrent gynecologic cancers

International Nuclear Information System (INIS)

Gemignani, Mary L.; Alektiar, Kaled M.; Leitao, Mario; Mychalczak, Boris; Chi, Dennis; Venkatraman, Ennapadam; Barakat, Richard R.; Curtin, John P.

2001-01-01

Objective: To determine the outcome for patients with recurrent gynecologic tumors treated with radical resection and combined high-dose intraoperative radiation therapy (HDR-IORT). Methods and Materials: Between November 1993 and June 1998, 17 patients with recurrent gynecologic malignancies underwent radical surgical resection and high-dose-rate brachytherapy. The mean age of the study group was 49 years (range 28-72 years). The site of the primary tumor was the cervix in 9 (53%) patients, the uterus in 7 (41%) patients, and the vagina in 1 (6%) patient. The treatment for the primary disease was surgery with or without adjuvant radiation in 14 (82%) patients and definitive radiation in 3 (18%) patients. The current surgery consisted of exenterative surgery in 10 (59%) patients and tumor resection in 7 (41%) patients. Complete gross resection was achieved in 13 (76%) patients. The mean HDR-IORT dose was 14 Gy (range 12-15). Additional radiation in the form of permanent Iodine-125 implant was given to 3 of 4 patients with gross residual disease. The median peripheral dose was 140 Gy. Results: With a median follow-up of 20 months (range 3-65 months), the 3-year actuarial local control (LC) rate was 67%. In patients with complete gross resection, the 3-year LC rate was 83%, compared to 25% in patients with gross residual disease, p<0.01. The 3-year distant metastasis disease-free and overall survival rates were 54% and 54%, respectively. The complications were as follows: gastrointestinal obstruction, 4 (24%); wound complications, 4 (24%); abscesses, 3 (18%); peripheral neuropathy, 3 (18%); rectovaginal fistula, 2 (12%); and ureteral obstruction, 2 (12%). Conclusion: Radical surgical resection and combined IORT for patients with recurrent gynecologic tumors seems to provide a reasonable local-control rate in patients who have failed prior surgery and/or definitive radiation. Patient selection is very important, however, as only those patients with complete gross

Protective effect of Nardostachys jatamansi on radiation induced anxiety and oxidative stress in mice

International Nuclear Information System (INIS)

Bandary, Satheesh; Suchetha Kumari, N.; Madhu, L.N.

2012-01-01

Nardostachys jatamansi (family Valerianaceae), an indigenous medicinal plant induces in organism a state of resistance against stress. It helps to promote physical and mental health augment resistance of the body against disease and has shown potent antioxidant activity. To study the anxiolytic and protective effect of 100 mg of ethanolic extract of Nardostachys jatamansi was studied on the mice exposed to 6 Gy Electron beam radiation (EBR). The animals were treated with 100 mg of Nardostachys jatamansi extract (NJE) for 15 days before radiation exposure. The anxiety status of animals observed once for every 3 days during experiment period. The level of lipid peroxidation and glutathione (GSH) was estimated 15 days after irradiation. The irradiation of animals resulted in an elevation in anxiety, lipid peroxidation and reduction in GSH. Treatment of mice with NJE before irradiation caused a significant depletion in anxiety, lipid peroxidation followed by significant elevation in GSH. Our results indicate that the protective activity of NJE on radiation induced anxiety and oxidative stress may be due to free radical scavenging and increased antioxidant level in mice. (author)

Gamma radiolysis of aliphatic sulfur compounds in aqueous solutions. A study to contribute to the analysis of the end products of the OH radical-induced oxidation of aliphatic mercaptanes, sulfides, and disulfides

International Nuclear Information System (INIS)

Weiss, J.

1982-01-01

By identifying and determining numerous hitherto unknown end products, the study in hand contributes to a better insight into the radiation chemical processes occurring in OH radical-induced oxidation of aliphatic sulfur compounds. An extraction method has been developed for the qualitative and quantitative analysis of end products in aqueous solution in order to determine these compounds down to the level of trace amounts. Separation of endproducts is achieved by means of gas chromatography and high-pressure liquid chromatography, subsequent identification by GC-MS analysis. Aliphatic mercaptanes are oxidized by OH radicals to thiyl radicals which after combination can be detected as disulfide. At high radiation doses, secondary reactions will lead to polysulfides of which the homologues could first be prepared as the pure substance. The end products of the γ-radiolysis of aliphatic thioethers are determined to be dithia compounds, symmetrical or asymmetrical disulfides, or polysulfides, depending on the thioethers. With some end products, the radiation chemical yield is found to be a function of the absorbed dose so that material balances are impossible. Intermediate thiyl, α-alkyl mercaptoalkyl or alkyl radicals can be captured by tetramethyl ethylene, cyclohexene or p-benzoquinone, and can then be identified as the relevant adducts. (orig./RB) [de

Grape (Vitis vinifera) extracts protect against radiation-induced oxidative stress and DNA damage

International Nuclear Information System (INIS)

Singha, Indrani; Das, Subir Kumar; Saxena, S.; Gautam, S.

2016-01-01

Ionizing radiation (IR) causes oxidative stress through the overwhelming generation of reactive oxygen species (ROS) in the living cells leading further to the oxidative damage to biomolecules. Grapes (Vitis vinifera) contain several bioactive phytochemicals and are the richest source of antioxidant. In this study, we investigated and compared in vitro antioxidant activity and DNA damage protective property of the grape extracts of four different cultivars, including the Thompson seedless, Flame seedless, Kishmish chorni and Red globe. The activities of ascorbic acid oxidase and catalase significantly (p<0.01) differed among extracts within the same cultivar, while that of peroxidase and polyphenol oxidase did not differ significantly among extracts of any cultivar. In vitro antioxidant activities were assessed by ferric-reducing antioxidant power (FRAP) assay and ABTS. The superoxide radical-scavenging activity was higher in the seed as compared to the skin or pulp of the same cultivar. DNA damage was evaluated in acellular system using pBR322 plasmid relaxation. Grape extract was able to effectively scavenge free radicals in vitro. It could significantly prevent radiation-induced DNA damage. Furthermore, the protective action of grape depends on the source of extract and type of the cultivars. (author)

REC-2006-A Fractionated Extract of Podophyllum hexandrum Protects Cellular DNA from Radiation-Induced Damage by Reducing the Initial Damage and Enhancing Its Repair In Vivo.

Science.gov (United States)

Chaudhary, Pankaj; Shukla, Sandeep Kumar; Sharma, Rakesh Kumar

2011-01-01

Podophyllum hexandrum, a perennial herb commonly known as the Himalayan May Apple, is well known in Indian and Chinese traditional systems of medicine. P. hexandrum has been widely used for the treatment of venereal warts, skin infections, bacterial and viral infections, and different cancers of the brain, lung and bladder. This study aimed at elucidating the effect of REC-2006, a bioactive fractionated extract from the rhizome of P. hexandrum, on the kinetics of induction and repair of radiation-induced DNA damage in murine thymocytes in vivo. We evaluated its effect on non-specific radiation-induced DNA damage by the alkaline halo assay in terms of relative nuclear spreading factor (RNSF) and gene-specific radiation-induced DNA damage via semi-quantitative polymerase chain reaction. Whole body exposure of animals with gamma rays (10 Gy) caused a significant amount of DNA damage in thymocytes (RNSF values 17.7 ± 0.47, 12.96 ± 1.64 and 3.3 ± 0.014) and a reduction in the amplification of β-globin gene to 0, 28 and 43% at 0, 15 and 60 min, respectively. Administrating REC-2006 at a radioprotective concentration (15 mg kg(-1) body weight) 1 h before irradiation resulted in time-dependent reduction of DNA damage evident as a decrease in RNSF values 6.156 ± 0.576, 1.647 ± 0.534 and 0.496 ± 0.012, and an increase in β-globin gene amplification 36, 95 and 99%, at 0, 15 and 60 min, respectively. REC-2006 scavenged radiation-induced hydroxyl radicals in a dose-dependent manner stabilized DPPH free radicals and also inhibited superoxide anions. Various polyphenols and flavonoides present in REC-2006 might contribute to scavenging of radiation-induced free radicals, thereby preventing DNA damage and stimulating its repair.

Investigation of physical detection markers in irradiated foods under different radiation sources and post-irradiation storage conditions

Energy Technology Data Exchange (ETDEWEB)

Kwon, Joong Ho; Kim, Gui Ran; Ahn, Jae Jun; Kim, Dong Gil; Jin, Qiong Wen; Park, Ju Hwan; Lee, Ji Hyun [Kyungpook National University, Daegu (Korea, Republic of)

2010-04-15

In PSL analysis, all unirradiated samples showed less than 700 (negative) photon counts (PCs). At 5 kGy, spice samples showed PCs in range of 700-5,000 (intermediate), while grains, legumes, root-crops, and seasonings samples showed PCs over 5,000 (positive). This PSL based-detection of radiation treatment was possible even after 24 months of storage. In TL analysis, TL glow curve was characteristically different between unirradiated and irradiated samples. Glow curves were observed in temperature ranges of 150-250 .deg. C for irradiated and over 300 .deg. C for unirradiated samples. TL ratio (TL{sub 1}/TL{sub 2}) provided valuable additional confirmations as unirradiated sample showed values less than 0.1, while irradiated sample showed more than 0.1. However, with storage time, TL intensity and TL ratio decreased but discrimination was still possible even after storage of 24 months. Samples stored at room temperature with exposure to direct or indirect light enhanced the mentioned decrease of TL intensity and TL ratio as compared to low temperature storage in dark room. In ESR analysis, legumes and spices showed radiation-induced cellulose radicals, while seasonings showed multi-component signals of radiation-induced crystalline sugar radical. These radiation-induced radicals could be potential markers for the detection of radiation treatments in subjected samples. The decreasing trend was also found for radiation-specific ESR signals of cellulose and crystalline sugar radicals during storage. However, radiation-induced radicals in legumes, powdered pepper and seasonings were detectable even after 6 months of storage

Free radical generation in post-irradiation period: an evidence from the conversion of xanthine dehydrogenase into xanthine oxidase

International Nuclear Information System (INIS)

Kale, R.K.

2003-01-01

Xanthine oxidoreductase (XOR) system which consists of xanthine dehydrogenase (XDH) and xathine oxidase (XO), is one of the major sources of free radicals in biological systems. XOR system is pre-dominantly present as XDH in the normal tissue and converts into free radical generating XO-Form in the damaged tissue. Therefore, XO-Form of XOR system, is expected to be mainly found in the radiolytically damaged tissue. In such an event, XO may catalyze the generation of free radicals and potentiate the radiation effects in post-irradiation period. Recent findings on the effect of ionizing radiation on XOR system in the liver of mice, peroxidative damage and lactate dehydrogenase support this possibility. From these results it has been hypothized that free radical generating systems could be activated in the radiolytically damaged cell and in turn contribute to the cause and complications of late effects and their persistence in post-irradiation period. This aspect may have great significance in understanding the radiation - induced damages. It may also have serious implication in various fields like radiation therapy, health physics, carcinogenesis, space travelling radiation exposures and post nuclear accident care. Further, it is suggested that efforts need to be made to search more system(s) which could be activated particularly at lower doses of radiation and generate free radicals in post-irradiation period

Radiation chemistry - extravaganza or an integral component of radiation processing of food

International Nuclear Information System (INIS)

Simic, M.G.; DeGraff, E.

1983-01-01

The role of radiation chemistry in radiation processing of foods is discussed in detail. A few examples demonstrating the relevance of the radiation chemistry of model systems to food-irradiation technology are given. The importance of irradiation parameters such as dose, dose rate, temperature, atmosphere, physical state and additives in achieving acceptable and high quality of irradiated foods are emphasized. A few examples of radiation-induced free radical reactions in model compounds relevant to foods are also discussed. (author)

Watson-Crick Base Pair Radical Cation as a Model for Oxidative Damage in DNA.

Science.gov (United States)

Feketeová, Linda; Chan, Bun; Khairallah, George N; Steinmetz, Vincent; Maitre, Philippe; Radom, Leo; O'Hair, Richard A J

2017-07-06

The deleterious cellular effects of ionizing radiation are well-known, but the mechanisms causing DNA damage are poorly understood. The accepted molecular events involve initial oxidation and deprotonation at guanine sites, triggering hydrogen atom abstraction reactions from the sugar moieties, causing DNA strand breaks. Probing the chemistry of the initially formed radical cation has been challenging. Here, we generate, spectroscopically characterize, and examine the reactivity of the Watson-Crick nucleobase pair radical cation in the gas phase. We observe rich chemistry, including proton transfer between the bases and propagation of the radical site in deoxyguanosine from the base to the sugar, thus rupturing the sugar. This first example of a gas-phase model system providing molecular-level details on the chemistry of an ionized DNA base pair paves the way toward a more complete understanding of molecular processes induced by radiation. It also highlights the role of radical propagation in chemistry, biology, and nanotechnology.

Radiation-induced myocardial perfusion abnormalities in breast cancer patients following external beam radiation therapy.

Science.gov (United States)

Eftekhari, Mohammad; Anbiaei, Robabeh; Zamani, Hanie; Fallahi, Babak; Beiki, Davood; Ameri, Ahmad; Emami-Ardekani, Alireza; Fard-Esfahani, Armaghan; Gholamrezanezhad, Ali; Seid Ratki, Kazem Razavi; Roknabadi, Alireza Momen

2015-01-01

Radiation therapy for breast cancer can induce myocardial capillary injury and increase cardiovascular morbidity and mortality. A prospective cohort was conducted to study the prevalence of myocardial perfusion abnormalities following radiation therapy of left-sided breast cancer patients as compared to those with right-sided cancer. To minimize potential confounding factors, only those patients with low 10-year risk of coronary artery disease (based on Framingham risk scoring) were included. All patients were initially treated by modified radical mastectomy and then were managed by postoperative 3D Conformal Radiation Therapy (CRT) to the surgical bed with an additional 1-cm margin, delivered by 46-50 Gy (in 2 Gy daily fractions) over a 5-week course. The same dose-adjusted chemotherapy regimen (including anthracyclines, cyclophosphamide and taxol) was given to all patients. Six months after radiation therapy, all patients underwent cardiac SPECT for the evaluation of myocardial perfusion. A total of 71 patients with a mean age of 45.3±7.2 years [35 patients with leftsided breast cancer (exposed) and 36 patients with right-sided cancer (controls)] were enrolled. Dose-volume histogram (DVH) [showing the percentage of the heart exposed to >50% of radiation] was significantly higher in patients with left-sided breast cancer. Visual interpretation detected perfusion abnormalities in 42.9% of cases and 16.7% of controls (P=0.02, Odds ratio=1.46). In semiquantitative segmental analysis, only apical (28.6% versus 8.3%, P=0.03) and anterolateral (17.1% versus 2.8%, P=0.049) walls showed significantly reduced myocardial perfusion in the exposed group. Summed Stress Score (SSS) of>3 was observed in twelve cases (34.3%), while in five of the controls (13.9%),(Odds ratio=1.3). There was no significant difference between the groups regarding left ventricular ejection fraction. The risk of radiation induced myocardial perfusion abnormality in patients treated with CRT on the

Radiation-induced centers in inorganic glasses

International Nuclear Information System (INIS)

Brekhovskikh, S.M.; Tyul'nin, V.A.

1988-01-01

The nature, structure and formation mechanisms of radiation-induced colour centers, EPR, luminescence, generated ionizing radiation in nonorganic oxide glasses are considered. Experimental material covering both fundamental aspects of radiation physics and glass chemistry, and aspects intimately connected with the creation of new materials with the given radiation-spectral characteristics, with possibilities to prepare radiation-stable and radiation-sensitive glasses is systematized and generalized. Considerable attention is paid to the detection of radiation-induced center binding with composition, glass structures redox conditions for their synthesis. Some new possibilities of practical application of glasses with radiation-induced centers, in particular, to record optical information are reflected in the paper

Influence of Cocoa Flavanols and Procyanidins on Free Radical-induced Human Erythrocyte Hemolysis

Directory of Open Access Journals (Sweden)

Qin Yan Zhu

2005-01-01

Full Text Available Cocoa can be a rich source of antioxidants including the flavan-3-ols, epicatechin and catechin, and their oligomers (procyanidins. While these flavonoids have been reported to reduce the rate of free radical-induced erythrocyte hemolysis in experimental animal models, little is known about their effect on human erythrocyte hemolysis. The major objective of this work was to study the effect of a flavonoid-rich cocoa beverage on the resistance of human erythrocytes to oxidative stress. A second objective was to assess the effects of select purified cocoa flavonoids, epicatechin, catechin, the procyanidin Dimer B2 and one of its major metabolites, 3ʹ-O-methyl epicatechin, on free radical-induced erythrocyte hemolysis in vitro. Peripheral blood was obtained from 8 healthy subjects before and 1, 2, 4 and 8 h after consuming a flavonoid-rich cocoa beverage that provided 0.25 g/kg body weight (BW, 0.375 or 0.50 g/kg BW of cocoa. Plasma flavanol and dimer concentrations were determined for each subject. Erythrocyte hemolysis was evaluated using a controlled peroxidation reaction. Epicatechin, catechin, 3ʹ-O-methyl epicatechin and (--epicatechin-(4β > 8epicatechin (Dimer B2 were detected in the plasma within 1 h after the consumption of the beverage. The susceptibility of erythrocytes to hemolysis was reduced significantly following the consumption of the beverages. The duration of the lag time, which reflects the capacity of cells to buffer free radicals, was increased. Consistent with the above, the purified flavonoids, epicatechin, catechin, Dimer B2 and the metabolite 3ʹ-O-methyl epicatechin, exhibited dose-dependent protection against AAPH-induced erythrocyte hemolysis at concentrations ranging from 2.5 to 20 μM. Erythrocytes from subjects consuming flavonoid-rich cocoa show reduced susceptibility to free radical-induced hemolysis (p < 0.05.

The cellular environment in computer simulations of radiation-induced damage to DNA

International Nuclear Information System (INIS)

Moiseenko, V.V.; Waker, A.J.; Prestwich, W.V.

1998-01-01

Radiation-induced DNA single- and double-strand breaks were modeled for 660 keV photon radiation and scavenger capacity mimicking the cellular environment. Atomistic representation of DNA in B form with a first hydration shell was utilized to model direct and indirect damage. Monte Carlo generated electron tracks were used to model energy deposition in matter and to derive initial spatial distributions of species which appear in the medium following radiolysis. Diffusion of species was followed with time, and their reactions with DNA and each other were modeled in an encounter-controlled manner. Three methods to account for hydroxyl radical diffusion in a cellular environment were tested: assumed exponential survival, time-limited modeling and modeling of reactions between hydroxyl radicals and scavengers in an encounter-controlled manner. Although the method based on modeling scavenging in an encounter-controlled manner is more precise, it requires substantially more computer resources than either the exponential or time-limiting method. Scavenger concentrations of 0.5 and 0.15 M were considered using exponential and encounter-controlled methods with reaction rate set at 3 x 10 9 dm 3 mol -1 s -1 . Diffusion length and strand break yields, predicted by these two methods for the same scavenger molarity, were different by 20%-30%. The method based on limiting time of chemistry follow-up to 10 -9 s leads to DNA damage and radical diffusion estimates similar to 0.5 M scavenger concentration in the other two methods. The difference observed in predictions made by the methods considered could be tolerated in computer simulations of DNA damage. (orig.)

The cellular environment in computer simulations of radiation-induced damage to DNA

International Nuclear Information System (INIS)

Moiseenko, V.V.; Hamm, R.N.; Waker, A.J.; Prestwich, W.V.

1988-01-01

Radiation-induced DNA single- and double-strand breaks were modeled for 660 keV photon radiation and scavenger capacity mimicking the cellular environment. Atomistic representation of DNA in B form with a first hydration shell was utilized to model direct and indirect damage. Monte Carlo generated electron tracks were used to model energy deposition in matter and to derive initial spatial distributions of species which appear in the medium following radiolysis. Diffusion of species was followed with time, and their reactions with DNA and each other were modeled in an encounter-controlled manner. Three methods to account for hydroxyl radical diffusion in cellular environment were tested: assumed exponential survival, time-limited modeling and modeling of reactions between hydroxyl radicals and scavengers in an encounter-controlled manner. Although the method based on modeling scavenging in an encounter-controlled manner is more precise, it requires substantially more computer resources than either the exponential or time-limiting method. Scavenger concentrations of 0.5 and 0.15 M were considered using exponential and encounter-controlled methods with reaction rate set at 3x10 9 dm 3 mol -1 s-1. Diffusion length and strand break yields, predicted by these two methods for the same scavenger molarity, were different by 20%-30%. The method based on limiting time of chemistry follow-up to 10 -9 s leads to DNA damage and radical diffusion estimates similar to 0.5 M scavenger concentration in the other two methods. The difference observed in predictions made by the methods considered could be tolerated in computer simulations of DNA damage. (author)

The chemistry of separations ligand degradation by organic radical cations

Energy Technology Data Exchange (ETDEWEB)

Mezyk, S.P.; Horne, G.P. [California State University at Long Beach, Long Beach, CA 90840 (United States); Mincher, B.J.; Zalupski, P.R. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Cook, A.R.; Wishart, J.F. [Chemistry Department, Brookhaven National Laboratory, New York, 11973 (United States)

2016-07-01

Solvent based extractions of used nuclear fuel use designer ligands in an organic phase extracting ligand complexed metal ions from an acidic aqueous phase. These extractions will be performed in highly radioactive environments, and the radiation chemistry of all these complexing agents and their diluents will play a major role in determining extraction efficiency, separation factors, and solvent-recycle longevity. Although there has been considerable effort in investigating ligand damage occurring in acidic water radiolysis conditions, only minimal fundamental kinetic and mechanistic data has been reported for the degradation of extraction ligands in the organic phase. Extraction solvent phases typically use normal alkanes such as dodecane, TPH, and kerosene as diluents. The radiolysis of such diluents produce a mixture of radical cations (R{sup .+}), carbon-centered radicals (R{sup .}), solvated electrons, and molecular products such as hydrogen. Typically, the radical species will preferentially react with the dissolved oxygen present to produce relatively inert peroxyl radicals. This isolates the alkane radical cation species, R{sup .+} as the major radiolytically-induced organic species that can react with, and degrade, extraction agents in this phase. Here we report on our recent studies of organic radical cation reactions with 2 ligands: CMPO and TODGA. Elucidating these parameters, and combining them with the known acidic aqueous phase chemistry, will allow a full, fundamental, understanding of the impact of radiation on solvent extraction based separation processes to be achieved. (authors)

Modulation of Ionizing Radiation Induced Oxidative Imbalance by Semi-Fractionated Extract of Piper betle: An In Vitro and In Vivo Assessment

Directory of Open Access Journals (Sweden)

Savita Verma

2010-01-01

Full Text Available The study was planned to evaluate modulatory effect of aqueous extract of Piper betle leaf (PBL on ionizing radiation mediated oxidative stress leading to normal tissues damage during radiotherapy and other radiation exposures. The total polyphenols and flavonoids known as free radical scavenger (chelators were measured in the extract. To ascertain antioxidant potential of PBL extract, we studied free radical scavenging, metal chelation, reducing power, lipid peroxidation inhibition and ferric reducing antioxidant properties (FRAP using in vitro assays. Mice were exposed to varied radiation doses administered with the same extract prior to irradiation to confirm its oxidative stress minimizing efficacy by evaluating ferric reducing ability of plasma, reduced glutathione, lipid peroxidation and micro-nuclei frequency. PBL extract was effective in scavenging DPPH (up to 92% at 100 µg/ml and superoxide radicals (up to 95% at 80 µg/ml, chelated metal ions (up to 83% at 50 µg/ml and inhibited lipid peroxidation (up to 45.65% at 500 µg/ml in a dose dependant manner using in vitro model. Oral administration of PBL extract (225 mg/kg body weight 1 hr before irradiation in mice significantly enhanced (p < 0.01 radiation abated antioxidant potential of plasma and GSH level in all the observed organs. The treatment with extract effectively lowered the radiation induced lipid peroxidation at 24 hrs in all the selected organs with maximum inhibition in thymus (p < 0.01. After 48 hrs, lipid peroxidation was maximally inhibited in the group treated with the extract. Frequency of radiation induced micronucleated cells declined significantly (34.78%, p < 0.01 at 24 hrs post-irradiation interval by PBL extract administration. The results suggest that PBL extract has high antioxidant potential and relatively non-toxic and thus could be assertively used to mitigate radiotherapy inflicted normal tissues damage and also injuries caused by moderate doses of

Efficacy of wheat germ oil in modulating radiation-induced heart damage in rats

International Nuclear Information System (INIS)

Said, U.Z.; Azab, Kh.Sh.

2006-01-01

Wheat Germ oil is a natural unrefined vegetable oil. It is an excellent source of vitamin E, octacosanol, linoleic and linolenic essential fatty acids, which may be beneficial in neutralizing the free oxygen radicals. This study was designed to investigate the cardio-protective efficacy of wheat germ oil, on radiation-induced oxidative damage in rat's heart. Wheat germ oil was supplemented by gavage to rats at a dose of 81 mg/ kg body wt for 10 successive days pre- and 7 successive days post-exposure to 7 Gy (single dose) of whole body gamma irradiation. The dose of wheat germ oil is equivalent to daily human nutritional supplementation quantity. The results revealed that whole body ?-irradiation of rats produced significant alterations in blood cells picture. The erythrocyte, leucocyte, platelet counts and hemoglobin levels decreased after irradiation. Also, radiation-induced biochemical disorders manifested by significant elevation in xanthine oxidase activity (XO) and thiobarbituric acid reactive substances (TBARS) level, with decrease in reduced glutathione (GSH) content in heart tissues, indicating depression in the antioxidant status. Serum lipid profile as total cholesterol, high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C) and triglycerides levels (TG) were significantly higher than normal control rats. Radiation exposure produced a significant rise in the activities of serum markers for heart damage as creatine phosphokinase (CPK), aspartate aminotransferase (AST) and lactic dehydrogenase (LDH) indicating acute cardiac toxicity. Moreover, the obtained results revealed abnormal electrophoretic pattern of LDH isoenzymes in the 7th day after exposure to gamma rays. Three bands only appear on the agarose film comparing with 4 bands in normal control rats. The rats that received wheat germ oil supplement showed significantly less severe damage and remarkable improvement in all of the measured parameters when compared to

Radiation-induced effects in organic systems. Final report

International Nuclear Information System (INIS)

Johnsen, R.H.

1982-01-01

This project, which is of twenty-seven years duration, has been devoted to furthering our basic understanding of the processes involved in the absorption and distribution of high-energy radiation in organic molecules. The early phases of the work were concerned with the gross chemical effects of radiation and included studies in a number of important classes of organic compounds including alcohols, aliphatic acids, aliphatic hydrocarbons, and aromatic hydrocarbons. Basic information was acquired through these studies that has led to a better understanding of the effects of high-energy radiation on condensed media. During this period the so-called protective effect of low concentrations of aromatic hydrocarbons was also studied. A contribution of lasting significance at this time was the development of a technique for the post-radiolysis analysis of trapped free radicals by photochemical means. A comprehensive series of papers on the reactions of thermal hydrogen atoms with frozen organic substrates represented the beginning of a new phase in the approach to the problems of radiation chemistry in this laboratory. Since that time the general philosophy guided the research has been to single out events or processes suspected of contributing to the gross-radiation effect and study them in isolation. Thus from 1970 on efforts were devoted to charge-exchange processes, ionization efficiencies (w-values), radical decay process in solids and ion-dissociation reactions. The first by means of a modified time-of-flight mass spectrometer, the second utilizing an ionization chamber constructed in the FSU shops, the third using electron spin resonance detection, and the last involving the use of a dual mass spectrometer, solid target system invented in our laboratory. The most productive of these efforts has been the radical decay work

Separation of photo-induced radical pair in cryptochrome to a functionally critical distance

DEFF Research Database (Denmark)

Solov'yov, Ilia; Domratcheva, Tatiana; Schulten, Klaus

2014-01-01

Cryptochrome is a blue light receptor that acts as a sensor for the geomagnetic field and assists many animals in long-range navigation. The magnetoreceptor function arises from light-induced formation of a radical pair through electron transfer between a flavin cofactor (FAD) and a triad...... of tryptophan residues. Here, this electron transfer is investigated by quantum chemical and classical molecular dynamics calculations. The results reveal how sequential electron transfer, assisted by rearrangement of polar side groups in the cryptochrome interior, can yield a FAD-Trp radical pair state...... step can overcome in speed both recombination (electron back-transfer) and proton transfer involving the radical pair reached after primary electron transfer....

Prophylactic role of melatonin against radiation induced damage in mouse cerebellum with special reference to Purkinje cells

Energy Technology Data Exchange (ETDEWEB)

Sisodia, Rashmi; Kumari, Seema; Verma, Rajesh Kumar; Bhatia, A L [Neurobiology Laboratory, Department of Zoology, University of Rajasthan, Jaipur 302004 (India)

2006-06-15

Melatonin, a hormone with a proven antioxidative efficacy, crosses all morphophysiological barriers, including the blood-brain barrier, and distributes throughout the cell. The present study is an attempt to investigate the prophylactic influence of a chronic low level of melatonin against an acute radiation induced oxidative stress in the cerebellum of Swiss albino mice, with special reference to Purkinje cells. After 15 days of treatment the mice were sacrificed at various intervals from 1 to 30 days. Biochemical parameters included lipid peroxidation (LPO) and glutathione (GSH) levels as the endpoints. The quantitative study included alterations in number and volume of Purkinje cells. Swiss albino mice were orally administered a very low dose of melatonin (0.25 mg/mouse/day) for 15 consecutive days before single exposure to 4 Gy gamma radiation. Melatonin checked the augmented levels of LPO, by approximately 55%, by day 30 day post-exposure. Radiation induced depleted levels of GSH could be raised by 68.9% by day 30 post-exposure. Radiation exposure resulted in a reduction of the volume of Purkinje cells and their total number. The administration of melatonin significantly protected against the radiation induced decreases in Purkinje cell volume and number. Results indicate the antioxidative properties of melatonin resulting in its prophylactic property against radiation induced biochemical and cellular alterations in the cerebellum. The findings support the idea that melatonin may be used as an anti-irradiation drug due to its potent free radical scavenging and antioxidative efficacy.

The effects of Α-tocopherol and ascorbic acid glucosides on radiation- and H2O2-induced decomposition of thymine in aqueous solution

International Nuclear Information System (INIS)

Brinkevich, S.D.; Lagutin, P.Yu.; Shadyro, O.I.

2008-01-01

The effects of ascorbic acid, ascorbic acid glycoside and α-tocopherol monoglycoside on radiation- and H 2 O 2 -induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, ascorbic acid glycoside was found to possess the most marked protecting properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of ascorbic acid and ascorbic acid glycoside, as well as properties of radical adducts formed during their interaction with OH radicals. (authors)

REC-2006—A Fractionated Extract of Podophyllum hexandrum Protects Cellular DNA from Radiation-Induced Damage by Reducing the Initial Damage and Enhancing Its Repair In Vivo

Science.gov (United States)

Chaudhary, Pankaj; Shukla, Sandeep Kumar; Sharma, Rakesh Kumar

2011-01-01

Podophyllum hexandrum, a perennial herb commonly known as the Himalayan May Apple, is well known in Indian and Chinese traditional systems of medicine. P. hexandrum has been widely used for the treatment of venereal warts, skin infections, bacterial and viral infections, and different cancers of the brain, lung and bladder. This study aimed at elucidating the effect of REC-2006, a bioactive fractionated extract from the rhizome of P. hexandrum, on the kinetics of induction and repair of radiation-induced DNA damage in murine thymocytes in vivo. We evaluated its effect on non-specific radiation-induced DNA damage by the alkaline halo assay in terms of relative nuclear spreading factor (RNSF) and gene-specific radiation-induced DNA damage via semi-quantitative polymerase chain reaction. Whole body exposure of animals with gamma rays (10 Gy) caused a significant amount of DNA damage in thymocytes (RNSF values 17.7 ± 0.47, 12.96 ± 1.64 and 3.3 ± 0.014) and a reduction in the amplification of β-globin gene to 0, 28 and 43% at 0, 15 and 60 min, respectively. Administrating REC-2006 at a radioprotective concentration (15 mg kg−1 body weight) 1 h before irradiation resulted in time-dependent reduction of DNA damage evident as a decrease in RNSF values 6.156 ± 0.576, 1.647 ± 0.534 and 0.496 ± 0.012, and an increase in β-globin gene amplification 36, 95 and 99%, at 0, 15 and 60 min, respectively. REC-2006 scavenged radiation-induced hydroxyl radicals in a dose-dependent manner stabilized DPPH free radicals and also inhibited superoxide anions. Various polyphenols and flavonoides present in REC-2006 might contribute to scavenging of radiation-induced free radicals, thereby preventing DNA damage and stimulating its repair. PMID:20008078

Influence of various scavengers of •OH radicals on the radiation sensitivity of yeast and bacteria.

Science.gov (United States)

Múčka, Viliam; Bláha, Pavel; Čuba, Václav; Červenák, Jaroslav

2013-12-01

To quantitatively investigate the influence of various •OH (hydroxyl radical) scavengers on the radiation sensitivity of yeast and bacteria, particularly to define the relationship between the protective effect of a scavenger and its •OH scavenging efficiency. In order to study the protective effect of •OH scavengers we used various concentrations of four scavengers (methanol, potassium formate, ethanol and ascorbic acid) in isotonic salt solutions. These solutions containing live yeast (Saccharomyces cerevisiae) or bacteria (Escherichia coli) were irradiated with (60)Co isotope γ -radiation using two different doses and dose rates. The number of surviving cells was determined prior to and after irradiation both in suspension with and without scavengers. The surviving fractions after irradiation with and without the scavenger were evaluated. The main results of the paper were: The surviving fraction increased approximately linearly within the measured interval with increasing concentration of the scavenger. The same dependences were found for the protecting effect depending on the scavenging efficiency. The slopes of these dependences (k) were found to be characteristic for each scavenger. The k value determined the degree in which the scavenging of •OH radicals participated in the protection of living cells. The protective effects of scavengers at the same scavenging efficiency were different and unique for each scavenger. No simple relation was found between the efficiency of scavenger k and the rate constant kOH of the reactions between scavengers and •OH radicals. Our results suggest that the studied scavengers effectively protected yeast and bacteria against ionizing radiation. Although the scavenging of •OH radicals seems to be important for protection of living cells, it is clearly not the only process on which the protection is based.

Radiation-induced camptocormia and dropped head syndrome. Review and case report of radiation-induced movement disorders

International Nuclear Information System (INIS)

Seidel, Clemens; Kuhnt, Thomas; Kortmann, Rolf-Dieter; Hering, Kathrin

2015-01-01

In recent years, camptocormia and dropped head syndrome (DHS) have gained attention as particular forms of movement disorders. Camptocormia presents with involuntary forward flexion of the thoracolumbar spine that typically increases during walking or standing and may severely impede walking ability. DHS is characterized by weakness of the neck extensors and a consecutive inability to extend the neck; in severe cases the head is fixed in a ''chin to chest position.'' Many diseases may underlie these conditions, and there have been some reports about radiation-induced camptocormia and DHS. A PubMed search with the keywords ''camptocormia,'' ''dropped head syndrome,'' ''radiation-induced myopathy,'' ''radiation-induced neuropathy,'' and ''radiation-induced movement disorder'' was carried out to better characterize radiation-induced movement disorders and the radiation techniques involved. In addition, the case of a patient developing camptocormia 23 years after radiation therapy of a non-Hodgkin's lymphoma of the abdomen is described. In total, nine case series of radiation-induced DHS (n = 45 patients) and - including our case - three case reports (n = 3 patients) about radiogenic camptocormia were retrieved. Most cases (40/45 patients) occurred less than 15 years after radiotherapy involving extended fields for Hodgkin's disease. The use of wide radiation fields including many spinal segments with paraspinal muscles may lead to radiation-induced movement disorders. If paraspinal muscles and the thoracolumbar spine are involved, the clinical presentation can be that of camptocormia. DHS may result if there is involvement of the cervical spine. To prevent these disorders, sparing of the spine and paraspinal muscles is desirable. (orig.) [de

Hematological Changes Induced by Mercury Ions and Ionizing Radiation in Experimental Animals

International Nuclear Information System (INIS)

Kim, Jin-Kyu; Lee, Yun-Jong; Choi, Dae-Seong; Kim, Ji-Hyang; Cebulska-Wasilewska, Antonina

2006-01-01

Toxic metals such as lead, chromium, cadmium, mercury and arsenic are widely found in our environment. Humans are exposed to these metals from numerous sources, including contaminated air, water, soil and food. Mercury, one of the most diffused and hazardous organ specific environmental contaminants, exists in a wide variety of physical and chemical states, each of which has unique characteristics for a target organ specificity. Although reports indicate that mercury induces deleterious damage, little is known about its effects on living organisms. Ionizing radiation, an extensively used therapeutic modality in oncology, not only eradicates neoplastic cells but also generates inevitable side effects for normal tissues. Such biological effects are made through the production of reactive oxygen species which include a superoxide anion, a hydroxyl radical and a hydrogen peroxide. These reactive species may contribute to the radiation-induced cytotoxicity (e.g., chromosome aberrations, protein oxidation, and muscle injury) and to the metabolic and morphologic changes (e.g., increased muscle proteolysis and changes in the central nervous system) in animals and humans. In the present study, radioimmunoassay of the cortisol in the serum and the analysis of the hematological components and enzymes related to a tissue injury were carried out to evaluate the effects of mercury chloride in comparison with those of ionizing radiation

Hematological Changes Induced by Mercury Ions and Ionizing Radiation in Experimental Animals

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin-Kyu; Lee, Yun-Jong; Choi, Dae-Seong [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of); Kim, Ji-Hyang [Biotechnology Research Institute, Seoul (Korea, Republic of); Cebulska-Wasilewska, Antonina [The Henryk Niewodniczanski Institute of Nuclear Physics, Krakow (Poland)

2006-07-01

Toxic metals such as lead, chromium, cadmium, mercury and arsenic are widely found in our environment. Humans are exposed to these metals from numerous sources, including contaminated air, water, soil and food. Mercury, one of the most diffused and hazardous organ specific environmental contaminants, exists in a wide variety of physical and chemical states, each of which has unique characteristics for a target organ specificity. Although reports indicate that mercury induces deleterious damage, little is known about its effects on living organisms. Ionizing radiation, an extensively used therapeutic modality in oncology, not only eradicates neoplastic cells but also generates inevitable side effects for normal tissues. Such biological effects are made through the production of reactive oxygen species which include a superoxide anion, a hydroxyl radical and a hydrogen peroxide. These reactive species may contribute to the radiation-induced cytotoxicity (e.g., chromosome aberrations, protein oxidation, and muscle injury) and to the metabolic and morphologic changes (e.g., increased muscle proteolysis and changes in the central nervous system) in animals and humans. In the present study, radioimmunoassay of the cortisol in the serum and the analysis of the hematological components and enzymes related to a tissue injury were carried out to evaluate the effects of mercury chloride in comparison with those of ionizing radiation.

Protective effect of Asparagus racemosus root extract against lethal total - body electron beam radiation induced damage in Swiss albino mice

International Nuclear Information System (INIS)

Sharmila, K.P.; Bhandary, B. Satheesh Kumar; Suchetha Kumari, N.; Bhat, Vadish S.; Shetty, Jayaram; Peter, Alex John; Jose, Jerish M.; Fernandes, Ronald

2016-01-01

To investigate the protective effect of Asparagus Racemosus Root ethanolic extract (ARE) in Swiss albino mice against acute lethal total - body Electron beam irradiation. Swiss Albino mice were used for the assessment of radiation induced sickness and 30 day survival analysis. Survival studies were determined using the Kaplan-Meier survival curves. The maximum survival was observed in the experimental mice pretreated with 200 mg/kg.b.wt. of ARE which also reduced the radiation sickness characteristics. This dose was considered as an optimal dose for radioprotection. Treatment of mice with ARE before irradiation delayed the onset of mortality as compared with the untreated irradiated controls. Present findings demonstrate the potential of ARE in mitigating radiation-induced mortality, which may be attributed to its free radical scavenging and increased antioxidant potential

Contribution of radiation-induced, nitric oxide-mediated bystander effect to radiation-induced adaptive response.

Science.gov (United States)

Matsumoto, H.; Ohnishi, T.

There has been a recent upsurge of interest in radiation-induced adaptive response and bystander effect which are specific modes in stress response to low-dose low-dose rate radiation Recently we found that the accumulation of inducible nitric oxide NO synthase iNOS in wt p53 cells was induced by chronic irradiation with gamma rays followed by acute irradiation with X-rays but not by each one resulting in an increase in nitrite concentrations of medium It is suggested that the accumulation of iNOS may be due to the depression of acute irradiation-induced p53 functions by pre-chronic irradiation In addition we found that the radiosensitivity of wt p53 cells against acute irradiation with X-rays was reduced after chronic irradiation with gamma rays This reduction of radiosensitivity of wt p53 cells was nearly completely suppressed by the addition of NO scavenger carboxy-PTIO to the medium This reduction of radiosensitivity of wt p53 cells is just radiation-induced adaptive response suggesting that NO-mediated bystander effect may considerably contribute to adaptive response induced by radiation

Free radicals in dicarboxylic acids: an e.s.r. study of radical conversions in γ-irradiated single crystals of glutaric acid and glutaric-2,2,4,4-d4 acid

International Nuclear Information System (INIS)

Bergene, R.; Minegishi, A.; Riesz, P.

1980-01-01

The γ-radiation-induced free radicals in single crystals of glutaric acid and glutaric-2,2,4,4-d 4 acid were studied in the temperature range 77-300 K by e.s.r. techniques. At 77 K the decarboxylation radical and the anion are stabilized. At higher temperatures the decarboxylation radical is found to be converted into a hydrogen abstraction radical with an activation energy of 6.3 +- 0.5 kcal/mole for the non-deuterated crystal. This radical is stable at room temperature. The anion seems to be converted to a unidentified intermediate radical which in turn is converted to the σ-acyl radical. An analysis of the g-value anisotropy and of the 13 C hyperfine splitting variation for this radical in the deuterated crystal is consistent with the assigned radical structure. By heat treatment the σ-acyl radical is converted to another form of the hydrogen abstraction radical with an activation energy of 9.6 +- 0.6 kcal/mole in the deuterated crystal. U.V.-light (lambda= 254 nm) transforms one of the room temperature radicals into the other. (author)

Relationship between free radical content in human tooth enamel and radiation dose

International Nuclear Information System (INIS)

Zhou Yongzeng; Wang Jiadong; Jia Xiaomei; Wu Ke; Cong Jianbo; Sun Cunpu

2000-01-01

Application of ESR technique of tooth enamel have become more and more wide-spread in accidental and retrospective dosimetry. The purpose of this paper is to study relationship between free radical content in tooth enamel and radiation dose. Method Samples of 25 Chinese adult teeth, 25 child permanent teeth and 35 milk teeth were used in the study. All teeth were obtained from patients in the course of dental practice. Tooth enamel was separated from dentine using dental drill and then crushed manually into grains of about 0.5-1.5 mm in diameter. The mass of each sample is 100 mg. Signal intensity of enamel samples was measured by ESR technique (Bruker-ESP300). Parameters used were modulation frequency 50 KHz, modulation amplitude 0.2 mT, time constant 41 ms, scan width 15 mT, microwave power 5 mw, room temperature. Samples of 25 adult teeth, 25 child permanent teeth and 35 milk teeth were divided into 5 dose groups, respectively, and irradiated with 60 Co γ-ray at dose rate of 0.48 Gy/min. Radiation doses of the 5 groups were 0.30, 0.50, 1.00, 3.00 and 5.00 Gy, respectively. After irradiation, each sample was subjected to ESR measurements. There is no significant difference in background signal intensity between male and female samples for both child permanent teeth and milk teeth. And also no significant difference in background signal intensity between child permanent teeth and milk teeth was observed. Results of study on adult teeth indicated that radiation sensitivity of different teeth is fairly uniform. Free radical content in enamel of child permanent teeth and milk teeth increases linearly with increasing of radiation dose, and similar results were obtained for adult teeth. Slope of the dose-response curve for adult teeth is somewhat steeper than that for milk teeth. There exists a linear relation between ESR signals intensity and radiation doses for adult teeth, child permanent and milk teeth. In the case of radiation accident, the dose-response curves

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Takashi [Nitto Denko Co. LTD., Shimohozumi 1-1-2, Ibaraki, Osaka 567-8680 (Japan); Ichikawa, Tsuneki [Division of Materials Chemistry, Graduate school of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)]. E-mail: ichikawa@eng.hokudai.ac.jp

2005-07-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon {gamma}-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M{sub n}R{sub 1}COOCH(C{sub 6}H{sub 5})R{sub 2}M{sub n}+e{sup -}->M{sub n}R{sub 1}COO{sup -}+{sup {center_dot}}CH(C{sub 6}H{sub 5})R{sub 2}M{sub n}. The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching.

Excimer laser corneal surgery and free oxygen radicals.

Science.gov (United States)

Bilgihan, K; Bilgihan, A; Akata, F; Hasanreisoğlu, B; Türközkan, N

1996-01-01

Corneal photoablation with 193 nm argon fluoride excimer laser is a new technique for the treatment of refractive errors and for removing corneal opacities and irregularities. Ultraviolet radiation and thermal injury induce free radical formation in the tissues. The aim of this study was to confirm the production of free radicals by excimer laser photoablation in rabbits. The thermal changes of the posterior corneal surface were recorded during excimer laser photoablation. The lipid peroxide (LPO) levels and superoxide dismutase (SOD) activities of aqueous humour were measured after excimer laser keratectomy. The aqueous LPO levels were not changed after excimer laser ablation, but both the thermal increase in the cornea during the photoablation and the decreased aqueous SOD activities suggest that free radicals are formed in the cornea during excimer laser keratectomy, and that they may be responsible for some of the complications of excimer laser corneal surgery.

Direct evidence of iNOS-mediated in vivo free radical production and protein oxidation in acetone-induced ketosis

Science.gov (United States)

Stadler, Krisztian; Bonini, Marcelo G.; Dallas, Shannon; Duma, Danielle; Mason, Ronald P.; Kadiiska, Maria B.

2008-01-01

Diabetic patients frequently encounter ketosis that is characterized by the breakdown of lipids with the consequent accumulation of ketone bodies. Several studies have demonstrated that reactive species are likely to induce tissue damage in diabetes, but the role of the ketone bodies in the process has not been fully investigated. In this study, electron paramagnetic resonance (EPR) spectroscopy combined with novel spin-trapping and immunological techniques has been used to investigate in vivo free radical formation in a murine model of acetone-induced ketosis. A six-line EPR spectrum consistent with the α-(4-pyridyl-1-oxide)-N-t-butylnitrone radical adduct of a carbon-centered lipid-derived radical was detected in the liver extracts. To investigate the possible enzymatic source of these radicals, inducible nitric oxide synthase (iNOS) and NADPH oxidase knockout mice were used. Free radical production was unchanged in the NADPH oxidase knockout but much decreased in the iNOS knockout mice, suggesting a role for iNOS in free radical production. Longer-term exposure to acetone revealed iNOS overexpression in the liver together with protein radical formation, which was detected by confocal microscopy and a novel immunospin-trapping method. Immunohistochemical analysis revealed enhanced lipid peroxidation and protein oxidation as a consequence of persistent free radical generation after 21 days of acetone treatment in control and NADPH oxidase knockout but not in iNOS knockout mice. Taken together, our data demonstrate that acetone administration, a model of ketosis, can lead to protein oxidation and lipid peroxidation through a free radical-dependent mechanism driven mainly by iNOS overexpression. PMID:18559982

Radiation-induced instability of human genome

International Nuclear Information System (INIS)

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

2014-01-01

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

Solved? The reductive radiation chemistry of alanine.

Science.gov (United States)

Pauwels, Ewald; De Cooman, Hendrik; Waroquier, Michel; Hole, Eli O; Sagstuen, Einar

2014-02-14

The structural changes throughout the entire reductive radiation-induced pathway of l-α-alanine are solved on an atomistic level with the aid of periodic DFT and nudged elastic band (NEB) simulations. This yields unprecedented information on the conformational changes taking place, including the protonation state of the carboxyl group in the "unstable" and "stable" alanine radicals and the internal transformation converting these two radical variants at temperatures above 220 K. The structures of all stable radicals were verified by calculating EPR properties and comparing those with experimental data. The variation of the energy throughout the full radiochemical process provides crucial insight into the reason why these structural changes and rearrangements occur. Starting from electron capture, the excess electron quickly localizes on the carbon of a carboxyl group, which pyramidalizes and receives a proton from the amino group of a neighboring alanine molecule, forming a first stable radical species (up to 150 K). In the temperature interval 150-220 K, this radical deaminates and deprotonates at the carboxyl group, the detached amino group undergoes inversion and its methyl group sustains an internal rotation. This yields the so-called "unstable alanine radical". Above 220 K, triggered by the attachment of an additional proton on the detached amino group, the radical then undergoes an internal rotation in the reverse direction, giving rise to the "stable alanine radical", which is the final stage in the reductive radiation-induced decay of alanine.

Radiation-Induced Graft Polymerization: Gamma Radiation and Electron Beam Technology for Materials Development

International Nuclear Information System (INIS)

Madrid, Jordan F.; Cabalar, Patrick Jay; Lopez, Girlie Eunice; Abad, Lucille V.

2015-01-01

The formation of functional hybrid materials by attaching polymer chains with advantageous tailored properties to the surface of a base polymer with desirable bulk character is an attractive application of graft copolymerization. Radiation-induced graft polymerization (RIGP) has been a popular approach for surface modification of polymers because of its merits over conventional chemical processes. RIGP, which proceeds primarily via free radical polymerization process, has the advantages such as simplicity, low cost, control over process and adjustment of the materials composition and structure. RIGP can be performed using either electron beam or gamma radiation and it can be applied to both synthetic and natural polymers. These merits make RIGP a popular research topic worldwide. Moreover, the materials synthesized and produced via RIGP has found applications, and were proposed to produce continuous impact, in the fields of medicine, agriculture, pollution remediation, rare earth and valuable metals recovery, fuel cell membrane synthesis and catalysis to name a few. From 2012 our group has performed electron beam and gamma radiation-induced graft polymerization of various monomers onto polymers of natural and synthetic origins (e.g. monomers - glycidyl methacrylate, styrene, acrylonitrile, N,N-dimethylaminoethyl methacrylate; base polymers – polyethylene/polypropylene nonwoven fabric, polypropylene nonwoven fabric pineapple fibers, cellulose nonwoven fabric microcrystalline cellulose). We tested these grafted materials for heavy metals (Pb, Ni, Cu) and organic molecule removal from aqueous solutions and E. coli activity (using reversible addition fragmentation chain transfer RAFT mediated grafting). The results clearly showed the success of materials modified via FIGP in these applications. Currently, we are studying the applications of grafted materials on treatment of waste waters from tanning industry, value addition to abaca nonwoven fabrics cell sheet

Radiation damage of DNA. Model for direct ionization of DNA

International Nuclear Information System (INIS)

Kobayashi, Kazuo; Tagawa, Seiichi

2004-01-01

Current aspects of radiation damage of DNA, particularly induced by the direct effect of radiation, and author's method of pulse radiolysis are described in relation to behavior of ions formed by radiation and active principles to induce the strand break. In irradiation of DNA solution in water, the direct effect of radiation is derived from ionization of DNA itself and indirect one, from the reaction between DNA and radicals generated from water molecules and the former direct one has been scarcely investigated due to difficulty of experimental approach. Radicals generated in sugar moiety of DNA are shown important in the strand break by recent studies on crystalline DNA irradiated by X-ray, DNA solution by electron and photon beams, hydrated DNA by γ-ray and by high linear energy transfer (LET) ion. Author's pulse radiolysis studies have revealed behaviors of guanine and adenine radical cations in dynamics of DNA oxidation. Since reactions described are the model, the experimental approach is thought necessary for elucidation of the actually occurring DNA damage in living cells. (N.I.)

Jatropha curcas leaf and bark fractions protect against ultraviolet radiation-B induced DNA damage in human peripheral blood lymphocytes.

Science.gov (United States)

Sundari, J; Selvaraj, R; Rajendra Prasad, N; Elumalai, R

2013-11-01

The present study is conducted to investigate the antioxidant potential of Jatropha curcas root bark extract (RB4 fraction) and leaf extract (L1 fraction), and to study their effects on UVB-radiation-induced DNA damage in cultured human blood lymphocytes. In this study, J. curcas showed strong antioxidant property in different free radical scavenging systems. Both the fractions effectively scavenged hydroxyl (OH), superoxide anion (O₂(·-)), 1,1-diphenyl-2-picrylhydrazyl (DPPH·) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical cation (ABTS(·+)) in a concentration-dependent manner. The IC₅₀ (Inhibitory Concentration 50) values of J. curcas fractions were compared to standard ascorbic acid used in this study. The antioxidant potential of a compound was directly proportional to the photoprotective effect. In this study, human peripheral blood lymphocytes (HPBL) were exposed to UVB-radiation and there was an increase in comet attributes (% tail DNA, tail length, tail movement and Olive tail moment). Jatropha curcas RB4 fraction and L1 fraction treatment before UVB-irradiation significantly decreased the % tail DNA, tail length, tail moment and Olive tail moment in irradiated HPBL. These results suggested that J. curcas exhibited strong antioxidant property and RB4 and L1 fractions protected UVB-radiation-induced DNA damage in HPBL. Copyright © 2013 Elsevier B.V. All rights reserved.

Does oxygen enhance the radiation: induced inactivation of penicillinase. Progress report, December 1, 1979-November 30, 1980

International Nuclear Information System (INIS)

Samuni, A.; Kalkstein, A.; Czapski, G.

1980-01-01

The radiation-induced inactivation of penicillinase in dilute aqueous solutions buffered with phosphate was studied, by examining enzyme radiosensitivity in the presence of various gases (He, O 2 , H 2 , N 2 O, N 2 O + O 2 ). The introduction of either N 2 O or O 2 was found to reduce the radiodamage. On the other hand H 2 or N 2 O + O 2 gas-mixture enhanced the radiosensitivity. In the presence of formate and oxygen, no enzyme inactivation was detected. The results indicated that the specific damaging efficiency of H atoms is almost four-fold higher than that of OH radical; therefore in phosphate buffer, where more than half of the free radicals are H atoms, it is the H radicals that are responsible for the majority of the damage. The superoxide radicals appeared to be completely inactive and did not contribute toward enzyme inactivation. Oxygen was shown to affect the radiosensitivity in two ways. On one side, it protected by converting e - /sub aq/ and H radicals into harmless O 2 - radicals. On the other side it increased the inactivation by enhancing the damage brought about by OH radicals (OER = 2.8). In the present case the oxygen effect of protection exceeded that of sensitization, thus giving rise to a moderate overall protection effect

Radiation induced chemical changes in foodstuffs model reaction systems and strawberries

International Nuclear Information System (INIS)

Breitfellner, F.

1999-10-01

In the first part of this work 4-hydroxybenzoic acid (4-HBA) and 4-hydroxybenzoic acid ethyl ester (4-HBAEE) were investigated in order to elucidate the reaction mechanisms leading to final products after reaction with OH-radicals (N 2 O-saturated and aerated aqueous solutions) at various pH. Irradiation of 5*10 -4 mol l -1 solutions of 4-HBA at pH 6.0 leads to formation of 3,4-dihydroxybenzoic acid and hydroquinone. In case of the ester neither hydroxylation nor decarboxylation products are observable. By means of pulse radiolysis it could be shown that water splitting from the ester OH-adducts is 17 times faster than from that of the acid. Therefore the main transients are phenoxyl radicals in case of the ester. At pH 10, where base catalyzed water elimination takes place, no hydroxylation products are observable either. In aerated solutions dihydroxy-compounds are formed with both substrates. In the case of 4-HBA 68 % of the OH-radicals result in 3,4-dihydroxyderivate, for 4-HBAEE these are only 25 %. Comparison of the initial degradation yields demonstrates 4-HBAEE to be 1.6-times more stable towards radiation. The second part of this work deals with radiation induced chemical changes in strawberries. Dose/concentration relationships could be obtained for 7 components, i.e. gallic acid, 4-hydroxybenzoic acid, cinnamic acid, 4-hydroxycinnamic acid, 3,4-dihydroxy-cinnamic acid, (-)-epicatechin and (+)-catechin. Linear dose relationships have been found for 4-HBA (formation) and (+)-catechin (degradation). In addition a specific radiolytically formed compound which can be used as marker for irradiation treatment of strawberries could be detected. There are strong indications that it is a radiolytic product of kaempferol, however, it could not yet be identified exactly. (author)

Enhancement of radiation-induced base release from nucleosides in alkaline solution: essential role of the O.- radical

International Nuclear Information System (INIS)

Scholes, M.L.; Schuchmann, M.N.; Sonntag, C. von

1992-01-01

The effect of pH on base release in the γ-radiolysis of N 2 O-saturated solutions of a number of nucleosides (including uridine, 3-methyluridine, 2', 3' -O-isopropylidene-uridine, and adenosine) has been investigated. For all these nucleosides, independent of the base or sugar moiety, base release is very low at pH below 10 (G∼(0.3-0.7) x 10 -7 mol J -1 ), but increases drastically to G∼(3-4) x 10 -7 mol J -1 at pH ≥ 13. It is concluded that the increase in base release at high pH is caused by the increasing participation of O .- , which, unlike . OH, attacks the nucleosides preferentially at their sugar moieties, and is not due to an OH - -induced radical transfer from the base to the sugar moiety. (author)

Radiation-induced heart injury

International Nuclear Information System (INIS)

Suzuki, Yoshihiko; Niibe, Hideo

1975-01-01

In order to identify radiation-induced heart injury and to differentiate it from heart disease, an attempt was made to clarify post-irradiation heart injury by investigating the histological changes which occur during the internal between the irradiation and the time of demonstrable histological changes. A study was made of 83 autopsies in which most of the primary neoplasms were breast cancers, lung cancers and mediastinal tumors. In 43 of these autopsies the heart had been irradiated. Sixty eight dd-strain mice were also used for microautoradiographic study. Histological changes in the heart were observed in 27 of the 43 cases receiving irradiation. The limit of the tolerance dose to the heart for indicating histological changes was 1220 ret in humans. The latent period without histological changes was 2.7 months after initiation of radiation therapy. Greater heart injury was observed after re-irradiation or after the combined therapy of radiation and chemotherapy especially mitomycin (MMC). The histological findings after treatment with MMC were similar to those of radiation-induced heart injury. Results of the study indicate that the damage is secondary to radiation-induced changes of the vascula connective tissue. (Evans, G.)

Free radicals in health and disease

International Nuclear Information System (INIS)

Gonet, B.

1993-01-01

Free radicals appear in the cells as the result of exogenic factors (ionizing radiation, UV) or reactions naturally occurring in the cell. Free radical reactions may cause destruction of macromolecules (DNA, lipids, proteins). Free radical pathology is important in many diseases and aging processes in organisms

Radiation damage in DNA

International Nuclear Information System (INIS)

Lafleur, V.

1978-01-01

A number of experiments are described with the purpose to obtain a better insight in the chemical nature and the biological significance of radiation-induced damage in DNA, with some emphasis on the significance of alkali-labile sites. It is shown that not only reactions of OH radicals but also of H radicals introduce breaks and other inactivating damage in single-standed phiX174 DNA. It is found that phosphate buffer is very suitable for the study of the reactions of H radicals with DNA, as the H 2 PO 4 - ions convert the hydrated electrons into H radicals. The hydrated electron, which does react with DNA, does not cause a detectable inactivation. (Auth.)

Anti-oxidation and scavenging effects of some extracts from Chinese medicines on free radicals

International Nuclear Information System (INIS)

Wang Chongdao; Qiang Yizhong; Lao Qinhua; Cui Fengmei; Shao Yuan; Sun Cunpu

1999-11-01

The inhibiting effects of Chinonin, Quercetin and Tannic Acid on the lipid oxidation induced by radiation exposure were investigated by means of a modified TBA spectrophotometry. The scavenging effects on free radicals caused by γ-irradiation exposure of the three active principles were observed by technique of ESR. The results showed that anti-oxidation effects of Chinonin and Quercetin were better than that of Tannic Acid, while the scavenging effects of the three active principles on free radicals were similar

Radiation-induced gene expression in human subcutaneous fibroblasts is predictive of radiation-induced fibrosis

DEFF Research Database (Denmark)

Rødningen, Olaug Kristin; Børresen-Dale, Anne-Lise; Alsner, Jan

2008-01-01

BACKGROUND AND PURPOSE: Breast cancer patients show a large variation in normal tissue reactions after ionizing radiation (IR) therapy. One of the most common long-term adverse effects of ionizing radiotherapy is radiation-induced fibrosis (RIF), and several attempts have been made over the last...... years to develop predictive assays for RIF. Our aim was to identify basal and radiation-induced transcriptional profiles in fibroblasts from breast cancer patients that might be related to the individual risk of RIF in these patients. MATERIALS AND METHODS: Fibroblast cell lines from 31 individuals......-treated fibroblasts. Transcriptional differences in basal and radiation-induced gene expression profiles were investigated using 15K cDNA microarrays, and results analyzed by both SAM and PAM. RESULTS: Sixty differentially expressed genes were identified by applying SAM on 10 patients with the highest risk of RIF...

Application of radiation-induced apoptosis in radiation oncology and radiation protection

International Nuclear Information System (INIS)

Crompton, N.E.A.; Emery, G.C.; Ozsahin, M.; Menz, R.; Knesplova, L.; Larsson, B.

1997-01-01

A rapid assay of the ability of lymphocytes to respond to radiation-induced damage is presented. Age and genetic dependence of radiation response have been quantified. The assay is sensitive to low doses of radiation. Its ability to assess the cytotoxic response of blood capillaries to radiation has been evaluated. (author)

Radiation-induced myocardial perfusion abnormalities in breast cancer patients following external beam radiation therapy

Directory of Open Access Journals (Sweden)

Mohammad Eftekhari

2015-01-01

Full Text Available Objective(s: Radiation therapy for breast cancer can induce myocardial capillary injury and increase cardiovascular morbidity and mortality. A prospective cohort was conducted to study the prevalence of myocardial perfusion abnormalities following radiation therapy of left-sided breast cancer patients as compared to those with right–sided cancer. Methods: To minimize potential confounding factors, only those patients with low 10-year risk of coronary artery disease (based on Framingham risk scoring were included. All patients were initially treated by modified radical mastectomy and then were managed by postoperative 3D Conformal Radiation Therapy (CRT to the surgical bed with an additional 1-cm margin, delivered by 46-50 Gy (in 2 Gy daily fractions over a 5-week course. The same dose-adjusted chemotherapy regimen (including anthracyclines, cyclophosphamide and taxol was given to all patients. Six months after radiation therapy, all patients underwent cardiac SPECT for the evaluation of myocardial perfusion. Results: A total of 71 patients with a mean age of 45.3±7.2 years [35 patients with leftsided breast cancer (exposed and 36 patients with right-sided cancer (controls] were enrolled. Dose-volume histogram (DVH [showing the percentage of the heart exposed to >50% of radiation] was significantly higher in patients with left-sided breast cancer. Visual interpretation detected perfusion abnormalities in 42.9% of cases and 16.7% of controls (P=0.02, Odds ratio=1.46. In semiquantitative segmental analysis, only apical (28.6% versus 8.3%, P=0.03 and anterolateral (17.1% versus 2.8%, P=0.049 walls showed significantly reduced myocardial perfusion in the exposed group. Summed Stress Score (SSS of>3 was observed in twelve cases (34.3%, while in five of the controls (13.9%,(Odds ratio=1.3. There was no significant difference between the groups regarding left ventricular ejection fraction. Conclusion: The risk of radiation induced myocardial

Interaction of radiation-generated radicals with myoglobin in aqueous solution

International Nuclear Information System (INIS)

Whitburn, K.D.; Hoffman, M.Z.

1984-01-01

The interaction of radiation-generated OH/H with oxymyoglobin (MbO 2 ) has been studied in the presence of catalase at pH 7.3 over the range of 5 to 510 μM O 2 . The conversion of MbO 2 to heme-modified products has been examined under conditions where depletion of O 2 in irradiated solutions both can and cannot be compensated by O 2 -transfer across the solution phase boundary. In the theoretical limit of [O 2 ] -> 0 in bulk solution, MbO 2 is converted stoichiometrically to ferri- and ferromyoglobin with G(-MbO 2 ) approx.= 6.0, G(ferroMb) approx.3.0, and G(ferriMb) approx.= 3.0. An increase in [O 2 ] in bulk solution beyond the zero-limit progressively suppresses the conversion of MbO 2 to the heme-modified derivatives. At [O 2 ] >300 μM, an O 2 -independent path of ferriMb formation with G approx.= 0.6 is evident. Two sources of ferriMb induced by OH/H are proposed: an O 2 -independent path involving direct oxidative attack of OH at the oxyferroheme, and O 2 -dependent paths of production of ferriMb and ferroMb involving the mediation of O 2 -scavengeable secondary hemeprotein radicals. It is suggested that the modifications of the heme group in the absence of O 2 are accompanied by redox modifications on the globin moiety. (author)

Free radicals in biology. Volume II

International Nuclear Information System (INIS)

Pryor, W.A.

1976-01-01

This volume continues the treatment of topics in free radical biology and free radical pathology from Volume I. In the first chapter, pyridinyl radicals, radicals which are models for those derived from NAD, are discussed. Pyridinyl radicals can be synthesized and isolated and directly studied in a number of chemical systems. The next chapter treats the role of glutathione in the cell. It is becoming even more apparent that this vital thiol controls a large number of important cellular functions. The GSH/GSSG balance has recently been implicated as a control for cellular development; this balance also may be important in relaying the effects of oxidants from one site to another in the body. The next chapter outlines the reactions of singlet oxygen; some of these involve free radicals and some do not. This reactive intermediate appears to be important both in photochemical smog and in cellular chemistry where singlet oxygen is produced by nonphotochemical processes. The production of free radicals from dry tissues, a controversial area with conflicting claims is reviewed. The next chapter outlines the current status of the studies of photochemical smog. The next two chapters treat specific reactive materials which are present in smog. The first discusses the chemistry of nitrogen oxides and ozone. The second chapter treats the chemistry of the peroxyacyl nitrites. These compounds, although present in only small concentration, are among the most toxic components of smog. The last two chapters treat radiation damage to proteins and radiation protection and radical reactions produced by radiation in nucleic acids

Grapevine fruit extract protects against radiation-induced oxidative stress and apoptosis in human lymphocyte

International Nuclear Information System (INIS)

Singha, Indrani; Das, Subir Kumar

2015-01-01

Ionizing radiation (IR) causes oxidative stress through overwhelming generation of reactive oxygen species (ROS) in the living cells leading the oxidative damage further to biomolecules. Grapevine (Vitis vinifera L.) posses several bioactive phytochemicals and is the richest source of antioxidants. In this study, we investigated V. vinifera for its phytochemical content, enzymes profile and, ROS-and oxidant-scavenging activities. We have also studied the fruit extract of four different grapevine viz., Thompson seedless, Flame seedless, Kishmish chorni and Red globe for their radioprotective actions in human lymphocytes. The activities of ascorbic acid oxidase and catalase significantly (P < 0.01) differed among extracts within the same cultivar, while that of peroxidase and polyphenol oxidase did not differ significantly. The superoxide radical-scavenging activity was higher in the seed as compared to the skin or pulp of the same cultivar. Pretreatment with grape extracts attenuated the oxidative stress induced by 4 Gy γ-radiation in human lymphocytes in vitro. Further, γ-radiation-induced increase in caspase 3/7 activity was significantly attenuated by grape extracts. These results suggest that grape extract serve as a potential source of natural antioxidants against the IR-induced oxidative stress and also inhibit apoptosis. Furthermore, the protective action of grape depends on the source of extract (seed, skin or pulp) and type of the cultivars. (author)

ESR studies of radiation induced radical products from linoleic acid and linolenic acid and the radioprotective effect by α-tocopherol

International Nuclear Information System (INIS)

Zhu Younan; Tu Tiecheng; Dong Jirong; Zhang Jiashan; Li Nianyun

1993-01-01

Primary radicals from the γ-radiolysis of air-saturated linoleic acid and linolenic acid at 77 K, and the subsequent secondary radicals appeared during the course of variable temperature elevation were investigated by ESR. The ESR spectrum from samples irradiated and observed at 77 K shows the presence of the radical anion doublet arise from the electron adducts of the carboxy groups and the poorly resolved broad singlet results from some carbon-centered radicals. Annealing to approximately 125 K which allows for molecular oxygen migration results in the formation of peroxyl radicals. At 247 K, the ESR spectrum is a multi-line pattern which is attributable to structure of the α-carbon radical superimposed on the pentadienyl radicals. The ESR spectra from linoleic acid-α-tocopherol and linolenic acid-α-tocopherol binary systems irradiated at 77 K and recorded at 140 K or 215 K revealed the characteristic similarity to that from α-tocopherol alone, no trace of ESR signal from either peroxyl or the composite pattern from superposition of pentadienyl radical and α-carbon radicals can be found out. Therefore α-tocopherol has exerted radioprotection effect on peroxidation of linoleic acid and linolenic acid

Cytoprotective Mechanisms Mediated by Polyphenols from Chilean Native Berries against Free Radical-Induced Damage on AGS Cells.

Science.gov (United States)

Ávila, Felipe; Theoduloz, Cristina; López-Alarcón, Camilo; Dorta, Eva; Schmeda-Hirschmann, Guillermo

2017-01-01

The prevalence of cytoprotective mechanisms induced by polyphenols such as activation of intracellular antioxidant responses (ICM) and direct free radical scavenging was investigated in native Chilean species of strawberries, raspberries, and currants. Human gastric epithelial cells were co- and preincubated with polyphenolic-enriched extracts (PEEs) from Chilean raspberries ( Rubus geoides ), strawberries ( Fragaria chiloensis ssp. chiloensis f . chiloensis ), and currants ( Ribes magellanicum ) and challenged with peroxyl and hydroxyl radicals. Cellular protection was determined in terms of cell viability, glyoxalase I and glutathione s-transferases activities, and carboxymethyl lysine (CML) and malondialdehyde levels. Our results indicate that cytoprotection induced by ICM was the prevalent mechanism for Rubus geoides and F. chiloensis . This agreed with increased levels of glyoxalase I and glutathione S-transferase activities in cells preincubated with PEEs. ORAC index indicated that F. chiloensis was the most efficient peroxyl radical scavenger. Moreover, ICM mediated by F. chiloensis was effective in protecting cells from CML accumulation in contrast to the protective effects induced by free radical scavenging. Our results indicate that although both polyphenol-mediated mechanisms can exert protective effects, ICM was the most prevalent in AGS cells. These results suggest a potential use of these native berries as functional food.

Radiation-induced pneumothorax

International Nuclear Information System (INIS)

Epstein, D.M.; Littman, P.; Gefter, W.B.; Miller, W.T.; Raney, R.B. Jr.

1983-01-01

Pneumothorax is an uncommon complication of radiation therapy to the chest. The proposed pathogenesis is radiation-induced fibrosis promoting subpleural bleb formation that ruptures resulting in pneumothorax. We report on two young patients with primary sarcomas without pulmonary metastases who developed spontaneous pneumothorax after irradiation. Neither patient had antecedent radiographic evidence of pulmonary fibrosis

VEGF secretion during hypoxia depends on free radicals-induced Fyn kinase activity in mast cells

International Nuclear Information System (INIS)

Garcia-Roman, Jonathan; Ibarra-Sanchez, Alfredo; Lamas, Monica; Gonzalez Espinosa, Claudia

2010-01-01

Research highlights: → Bone marrow-derived mast cells (BMMCs) secrete functional VEGF but do not degranulate after Cobalt chloride-induced hypoxia. → CoCl 2 -induced VEGF secretion in mast cells occurs by a Ca 2+ -insensitive but brefeldin A and Tetanus toxin-sensitive mechanism. → Trolox and N-acetylcysteine inhibit hypoxia-induced VEGF secretion but only Trolox inhibits FcεRI-dependent anaphylactic degranulation in mast cells. → Src family kinase Fyn activation after free radical production is necessary for hypoxia-induced VEGF secretion in mast cells. -- Abstract: Mast cells (MC) have an important role in pathologic conditions such as asthma and chronic obstructive pulmonary disease (COPD), where hypoxia conduce to deleterious inflammatory response. MC contribute to hypoxia-induced angiogenesis producing factors such as vascular endothelial growth factor (VEGF), but the mechanisms behind the control of hypoxia-induced VEGF secretion in this cell type is poorly understood. We used the hypoxia-mimicking agent cobalt chloride (CoCl 2 ) to analyze VEGF secretion in murine bone marrow-derived mast cells (BMMCs). We found that CoCl 2 promotes a sustained production of functional VEGF, able to induce proliferation of endothelial cells in vitro. CoCl 2 -induced VEGF secretion was independent of calcium rise but dependent on tetanus toxin-sensitive vesicle-associated membrane proteins (VAMPs). VEGF exocytosis required free radicals formation and the activation of Src family kinases. Interestingly, an important deficiency on CoCl 2 -induced VEGF secretion was observed in Fyn kinase-deficient BMMCs. Moreover, Fyn kinase was activated by CoCl 2 in WT cells and this activation was prevented by treatment with antioxidants such as Trolox and N-acetylcysteine. Our results show that BMMCs are able to release VEGF under hypoxic conditions through a tetanus toxin-sensitive mechanism, promoted by free radicals-dependent Fyn kinase activation.

VEGF secretion during hypoxia depends on free radicals-induced Fyn kinase activity in mast cells

Energy Technology Data Exchange (ETDEWEB)

Garcia-Roman, Jonathan; Ibarra-Sanchez, Alfredo; Lamas, Monica [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados del IPN (Cinvestav, IPN) (Mexico); Gonzalez Espinosa, Claudia, E-mail: cgonzal@cinvestav.mx [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados del IPN (Cinvestav, IPN) (Mexico)

2010-10-15

Research highlights: {yields} Bone marrow-derived mast cells (BMMCs) secrete functional VEGF but do not degranulate after Cobalt chloride-induced hypoxia. {yields} CoCl{sub 2}-induced VEGF secretion in mast cells occurs by a Ca{sup 2+}-insensitive but brefeldin A and Tetanus toxin-sensitive mechanism. {yields} Trolox and N-acetylcysteine inhibit hypoxia-induced VEGF secretion but only Trolox inhibits Fc{epsilon}RI-dependent anaphylactic degranulation in mast cells. {yields} Src family kinase Fyn activation after free radical production is necessary for hypoxia-induced VEGF secretion in mast cells. -- Abstract: Mast cells (MC) have an important role in pathologic conditions such as asthma and chronic obstructive pulmonary disease (COPD), where hypoxia conduce to deleterious inflammatory response. MC contribute to hypoxia-induced angiogenesis producing factors such as vascular endothelial growth factor (VEGF), but the mechanisms behind the control of hypoxia-induced VEGF secretion in this cell type is poorly understood. We used the hypoxia-mimicking agent cobalt chloride (CoCl{sub 2}) to analyze VEGF secretion in murine bone marrow-derived mast cells (BMMCs). We found that CoCl{sub 2} promotes a sustained production of functional VEGF, able to induce proliferation of endothelial cells in vitro. CoCl{sub 2}-induced VEGF secretion was independent of calcium rise but dependent on tetanus toxin-sensitive vesicle-associated membrane proteins (VAMPs). VEGF exocytosis required free radicals formation and the activation of Src family kinases. Interestingly, an important deficiency on CoCl{sub 2}-induced VEGF secretion was observed in Fyn kinase-deficient BMMCs. Moreover, Fyn kinase was activated by CoCl{sub 2} in WT cells and this activation was prevented by treatment with antioxidants such as Trolox and N-acetylcysteine. Our results show that BMMCs are able to release VEGF under hypoxic conditions through a tetanus toxin-sensitive mechanism, promoted by free radicals

Radiation induced sarcomas of bone following therapeutic radiation

International Nuclear Information System (INIS)

Kim, J.H.; Chu, F.C.H.; Woodward, H.Q.; Huvos, A.

1983-01-01

Because of new therapeutic trends of multi-modality and the importance of late effects, we have updated our series of radiation induced bone sarcomas seen at Memorial Sloan-Kettering Cancer Center over the past four decades. A total of 37 cases of bone sarcoma arising from normal bone in the irradiated field was analyzed. The median for latent period from irradiation to diagnosis of bone sarcoma was 11 years with a minimum latent period of four years. The median radiation dose for the bone sarcoma was 6000 rad in 6 weeks with a minimum total radiation dose of 3000 rad in 3 weeks. We have found nine patients who developed bone sarcomas in the radiation field after successful treatment of Hodgkin's disease. Criteria for radiation induced bone sarcomas and the magnitude of the risk of bone sarcomas are briefly discussed

Heavy-ion-induced sucrose radicals investigated using EPR and UV spectroscopy

Science.gov (United States)

Nakagawa, Kouichi; Karakirova, Yordanka; Yordanov, Nicola D.

2015-01-01

The potential use of a sucrose dosimeter for estimating both linear energy transfer (LET) and the absorbed dose of heavy ion and X-ray radiation was investigated. The stable free radicals were produced when sucrose was irradiated with heavy ions, such as helium, carbon, silicon and neon ions, and when the X-ray radiation was similar to the obtained electron paramagnetic resonance (EPR) spectra, which were ∼7 mT wide and composed of several hyperfine structures. In addition, the total spin concentration resulting from heavy-ion irradiation increased linearly as the absorbed dose increased, and decreased logarithmically as the LET increased. These empirical relations imply that the LET at a certain dose can be determined from the spin concentration. For sucrose and alanine, both cross-sections following C-ion irradiation with a 50 Gy dose were ∼1.3 × 10−12 [μm2], taking into account the molecular size of the samples. The values of these cross-sections imply that multiple ionizing particles were involved in the production of stable radicals. Furthermore, UV absorbance at 267 nm of an aqueous solution of irradiated sucrose was found to linearly increase with increasing absorbed dose. Therefore, the EPR and UV results suggest that sucrose can be a useful dosimeter for heavy-ion irradiation. PMID:25480828

Tatooing of tumor borders in cancer of the oral cavity oropharynx as a guide for orientation in radical operation after radiation

International Nuclear Information System (INIS)

Steinert, R.; Sesterhenn, K.; Rose, K.G.

1982-01-01

To improve the local rate of success or the conversion of cancers of the cavum oris and of the oropharynx which are inoperable because of their local situation, preoperative radiation is carried out in cases where this is appropriate. The radiation and the radical operation must be coordinated with each other. For this purpose the borders of the cancer are marked by tatooing them with ink. The tatooing makes it possible both to judge the effects of the radiation accurately and to locate the borders of the tumor with the naked eye after radiation treatment in apparently healthy tissues. In this way it is possible to perform the radical operation with an adequate safety margin around the pre-therapeutic borders of the tumor. With this method the rate of success in tongue-body, tongue-ground and tonsil cancers can be improved. (orig.) [de

Reaction of misonidazole with DNA radicals and its effect on the template activity of DNA

International Nuclear Information System (INIS)

Endoh, Daiji; Kuwabara, Mikinori; Sato, Fumiaki; Yoshii, Giichi.

1985-01-01

After calf thymus DNA was gamma-irradiated in the solid state in vacuo and subsequently dissolved in aqueous solution containing misonidazole (3 mM) under hypoxic condition, the frequency of single-strand breaks and alkali-labile sites in DNA and the amount of misonidazole bound to DNA were measured. The presence of misonidazole converted the precursor radicals, which otherwise results in single-strand breaks, to alkali-labile sites, and the amount of alkali-labile sites increased linearly with increasing radiation dose. The amount of misonidazole bound to DNA also increased linearly with increasing radiation dose. The biological meaning of the changes in the frequency of single-strand breaks and alkali-labile sites by the reaction of misonidazole with DNA radicals and of binding misonidazole with DNA was examined using a model system to measure the template activity of DNA for RNA synthesis in vitro. The conversion of DNA radicals to alkali-labile sites protected the radiation-induced decrease in the template activity of DNA, while the adduct formation of misonidazole had no effect on it. (author)

Radiation-induced bone neoplasma in facial cranium

Energy Technology Data Exchange (ETDEWEB)

Zomer-Drozda, J; Buraczewska-Lipinska, H; Buraczewski, J [Instytut Onkologii, Warsaw (Poland)

1976-01-01

Radiation-induced bone neoplasms in the region of facial cranium account for about 40% of all radiation-induced tumours of bones, although the number of cases with lesions irradiated in this area is proportionally much lower than the number of cases treated with radiotherapy in other parts of the body. Four personal cases of radiation-induced tumours with complicated course are reported. Attention is called to the value of radiological investigations in the diagnosis of bone diseases and in differential diagnosis of radiation-induced tumours of bones.

Efficiency of radical yield in alkylthymine and alkyluracil by high-LET irradiation

International Nuclear Information System (INIS)

Nakagawa, Seiko; Ohta, Nobuaki; Murakami, Takeshi

2010-01-01

Penthylthymines and hexyl-, nonyl-, and decyl- uracils were irradiated by C-ion (3.5 GeV) and γ-ray at 77 K. ESR spectra were measured to study radiation induced radicals in the temperature range from 108 to 273 K. A dihydro-5-yl (5-yl) radical formed by H addition to C6 carbon and a secondary alkyl radical by C-H bond fission at the second carbon from the end of the alkyl group were produced at 108 K. A dihydrouracil-6-yl (6-yl) radical formed by H addition to C5 carbon increased with increasing temperature for alkyluracils. The spectral feature obtained by C-ion irradiation was coincident with that by γ-irradiation. Total radical yields increased by alkylation and with increasing the length of alkyl chain. Yields of both 5-yl and secondary alkyl radicals irradiated by C-ion were less than those by γ-ray for penthylthymines and hexyluracil. On the contrary, radical yields were almost the same between ion and γ-ray irradiation for nonyl- and decyl-uracil. Mechanism of radical formation and effect of high-LET irradiation were discussed.

OH radical induced depolymerization of poly(methacrylic acid)

Science.gov (United States)

Ulanski, Piotr; Bothe, Eberhard; von Sonntag, Clemens

1999-05-01

Hydroxyl radicals (generated pulse radiolytically in dilute N 2O-saturated aqueous solutions) react with poly(methacrylic acid) producing two kinds of radicals. The primary radical is converted into a secondary one by H-abstraction ( k=3.5 × 10 2 s -1) as monitored by changes in the UV spectrum. Subsequently, the secondary radicals undergo chain scission ( k=1.8 s -1 at pH 7-9). This process has been followed both by spectrophotometry as well as by conductometry. In competition with the bimolecular decay of the radicals the ensuing end-chain radicals undergo efficient depolymerization resulting in the release of monomer. Since the lifetime of the radicals is much longer at high pH, where the polymer attains a rod-like conformation, depolymerization is most efficient in basic solution.

Radiation-induced synthesis of poly(acrylic acid) nanogels

Science.gov (United States)

Matusiak, Malgorzata; Kadlubowski, Slawomir; Ulanski, Piotr

2018-01-01

Nanogel is a two-component system of a diameter in the range of tens of nanometers, consisting of an intramolecularly crosslinked polymer chain and solvent, typically water, filling the space between segments of the macromolecule. Microgels are bigger than nanogels and their size range is between 100 nm to 100 μm. One of the methods used for synthesizing nanogels is linking the segments of a single macromolecule with the use of ionizing radiation, by intramolecular recombination of radiation-generated polymer radicals. The main advantage of this technique is absence of monomers, catalysts, surfactants or crosslinking agents. This method is an interesting alternative way of synthesizing polymeric carriers for biomedical applications. The aim of the study was radiation synthesis and characterization of poly(acrylic acid) - PAA - nanogels and microgels. The physico-chemical properties were described by determination of weight-average molecular weight and dimensions (radius of gyration, hydrodynamic radius) of the nanogels and microgels. Influence of polymer concentration and dose on these parameters was analyzed. Adjusting the PAA concentration and absorbed dose, one can control the molecular weight and dimensions of nanogels. The solutions of PAA were irradiated with two sources of ionizing radiation: γ-source and electron accelerator. The former method yields mainly microgels due to prevailing intermolecular crosslinking, while the latter promotes intramolecular recombination of PAA-derived radicals and in consequence formation of nanogels. In the future radiation-synthesized PAA nanogels, after functionalization, will be tested as carriers for delivering radionuclides to the tumor cells.

X-ray radiation induced bystander effects of human glioblastoma T98G cells under hypoxia condition

International Nuclear Information System (INIS)

Zhang Jianghong; Jin Yizun; Shao Chunlin; Prise, K.M.

2008-01-01

Non-irradiated bystander human glioblastoma T98G cells were co-cultured (CC) with irradiated cells or treated with conditioned medium (CM) from irradiated cells under hypoxic condition, then micronucleus (MN) of both irradiated cells and bystander cells were measured for the investigation of radiation induced bystander effect and its mechanism. It has been found that the MN yield (Y MN ) of non-irradiated bystander T98G cells is obviously enhanced after the cell co-culture, or CM treatment, but this increment is diminished by free radical scavenger, dimethyl sulfoxide (DMSO). When hypoxic or normoxic T98G cells are treated with CM obtained from irradiated cells under either hypoxic or normoxic condition, the biggest bystander response has been observed in the group of hypoxic by- stander cells treated with CM from irradiated normoxic cells. However, all of these increments of bystander Y MN could be eliminated by aminoguanidine, an iNOS inhibitor. Therefore, under hypoxic condition, free radicals, especially reactive oxygen species and nitric oxide, are involved in the bystander response induced by irradiated T98G cells. (authors)

Inhibitory effect of magnesium sulfate on reaction of lipid hyperoxidation after radiation-induced acute brain injuries

International Nuclear Information System (INIS)

Wang Lili; Zhou Juying; Yu Zhiying; Qin Songbing; Xu Xiaoting; Li Li; Tu Yu

2007-01-01

Objective: To explore the protection of magnesium sulfate (MgSO 4 ) on radiation-induced acute brain injuries. Methods: 60 maturity Sprague-Dawley (SD) rats were randomly divided into 3 groups: blank control group, experimental control group and experimental-therapeutic group. The whole brain of SD rats of experimental control group and experimental-therapeutic group was irradiated to a dose of 20 Gy using 6 MeV electron. MgSO 4 was injected intraperitoneally into the rats of experimental-therapeutic group before and after irradiation for five times. At different time points ranging from the 1 d, 7 d, 14 d, 30 d after irradiation, the brain tissue were taken. The xanthine oxidase and colorimetric examination were used to measure the superoxide dismutase (SOD) and malonyldialdehyde (MDA) respectively in the rat brain respectively. Results: Compared with blank control group, the SOD in brain of experimental control group decreased significantly (P 4 used in early stage can inhibit the lipid peroxidation after radiation-induced acute brain injuries and alleviate the damage induced by free radicals to brain tissue. (authors)

Effects of radiation on DNA

International Nuclear Information System (INIS)

Braddock, M.

1985-07-01

The hydroxyl radical (OH radical) is the most damaging radical produced by the effect of ionizing radiation in water. The rate of reaction of the OH radical with purified, native and isodisperse DNA has been determined as compared with calf thymus DNA. This has been achieved by direct observation of the rate of formation of the DNA-OH radical adduct, and by competition with SCN - . Results obtained from direct observation are consistent with calculations which have been performed using the encounter frequency model of Braams and Ebert. However, results obtained for OH radical with DNA derived from competition plots suggest a rate constant somewhat lower than that obtained from direct observation. The relative merits of both techniques are discussed. In order to study the effect of energy deposited directly in the DNA, dry films of purified plasmid DNA have been irradiated in a system where the indirect effects of radical interaction have been minimized. The present results indicate that with different molecular lengths of plasmid DNA, non-random breakage may occur, and that additional damage may be brought about at sites of previously existing damage. Differences in the sensitivity of plasmid DNA molecules of varying lengths to radiation induced double strand breaks have been demonstrated. (author)

Regulation of radiation-induced protein kinase Cδ activation in radiation-induced apoptosis differs between radiosensitive and radioresistant mouse thymic lymphoma cell lines

International Nuclear Information System (INIS)

Nakajima, Tetsuo; Yukawa, Osami; Tsuji, Hideo; Ohyama, Harumi; Wang, Bing; Tatsumi, Kouichi; Hayata, Isamu; Hama-Inaba, Hiroko

2006-01-01

Protein kinase Cδ (PKCδ) has an important role in radiation-induced apoptosis. The expression and function of PKCδ in radiation-induced apoptosis were assessed in a radiation-sensitive mouse thymic lymphoma cell line, 3SBH5, and its radioresistant variant, XR223. Rottlerin, a PKCδ-specific inhibitor, completely abolished radiation-induced apoptosis in 3SBH5. Radiation-induced PKCδ activation correlated with the degradation of PKCδ, indicating that PKCδ activation through degradation is involved in radiation-induced apoptosis in radiosensitive 3SBH5. In radioresistant XR223, radiation-induced PKCδ activation was lower than that in radiosensitive 3SBH5. Cytosol PKCδ levels in 3SBH5 decreased markedly after irradiation, while those in XR223 did not. There was no apparent change after irradiation in the membrane fractions of either cell type. In addition, basal cytosol PKCδ levels in XR223 were higher than those in 3SBH5. These results suggest that the radioresistance in XR223 to radiation-induced apoptosis is due to a difference in the regulation of radiation-induced PKCδ activation compared to that of 3SBH5. On the other hand, Atm -/- mouse thymic lymphoma cells were more radioresistant to radiation-induced apoptosis than wild-type mouse thymic lymphoma cells. Irradiated wild-type cells, but not Atm -/- cells, had decreased PKCδ levels, indicating that the Atm protein is involved in radiation-induced apoptosis through the induction of PKCδ degradation. The decreased Atm protein levels induced by treatment with Atm small interfering RNA had no effect on radiation-induced apoptosis in 3SBH5 cells. These results suggest that the regulation of radiation-induced PKCδ activation, which is distinct from the Atm-mediated cascade, determines radiation sensitivity in radiosensitive 3SBH5 cells

UV-generated free radicals (FR) in skin: Their prevention by sunscreens and their induction by self-tanning agents

Science.gov (United States)

Jung, K.; Seifert, M.; Herrling, Th.; Fuchs, J.

2008-05-01

In the past few years, the cellular effects of ultraviolet (UV) irradiation induced in skin have become increasingly recognized. Indeed, it is now well known that UV irradiation induces structural and cellular changes in all the compartments of skin tissue. The generation of reactive oxygen species (ROS) is the first and immediate consequence of UV exposure and therefore the quantitative determination of free radical reactions in the skin during UV radiation is of primary importance for the understanding of dermatological photodamage. The RSF method (radical sun protection factor) herein presented, based on electron spin resonance spectroscopy (ESR), enables the measurement of free radical reactions in skin biopsies directly during UV radiation. The amount of free radicals varies with UV doses and can be standardized by varying UV irradiance or exposure time. The RSF method allows the determination of the protective effect of UV filters and sunscreens as well as the radical induction capacity of self-tanning agents as dihydroxyacetone (DHA). The reaction of the reducing sugars used in self-tanning products and amino acids in the skin layer (Maillard reaction) leads to the formation of Amadori products that generate free radicals during UV irradiation. Using the RSF method three different self-tanning agents were analyzed and it was found, that in DHA-treated skin more than 180% additional radicals were generated during sun exposure with respect to untreated skin. For this reason the exposure duration in the sun must be shortened when self-tanners are used and photoaging processes are accelerated.

Radiation damage to DNA constituents

International Nuclear Information System (INIS)

Bergene, R.

1977-01-01

The molecular changes of the DNA molecule, in various systems exposed to inoizing radiation, have been the subject of a great number of studies. In the present work electron spin resonance spectroscopy (ESR) has been applied to irradiated crystalline systems, in particular single crystals of DNA subunits and their derivatives. The main conclusions about the molecular damage are based on this technique in combination with molecular orbital calculations. It should be emphasized that the ESR technique is restricted to damage containing unpaired electrons. These unstable intermediates called free radicals seem, however, to be involved in all molecular models describing the action of radiation on DNA. One of the premises for a detailed theory of the radiation induced reactions at the physico-chemical level seems to involve exact knowledge of the induced free radicals as well as the modes of their formation and fate. For DNA, as such, it is hardly possible to arrive at such a level of knowledge since the molecular complexity prevents selective studies of the many different radiation induced products. One possible approach is to study the free radicals formed in the constituents of DNA. In the present work three lines of approach should be mentioned. The first is based on the observation that radical formation in general causes only minor structural alterations to the molecule in question. The use of isotopes with different spin and magnetic moment (in particular deuterium) may also serve a source of information. Deuteration leads to a number of protons, mainly NH - and OH, becoming substituted, and if any of these are involved in interactions with unpaired protons the resonance pattern is influeneed. The third source of information is molecular orbital calculation. The electron spin density distribution is a function in the three dimensional space based on the system's electronic wave functions. This constitutes the basis for the idea that ESR data can be correlated with

Binding of a nitroxyl to radiation-induced DNA transients in repair and repair deficient of E. coli K-12

Energy Technology Data Exchange (ETDEWEB)

Wold, E; Brustad, T [Norsk Hydros Institutt for Kreftforskning, Oslo

1975-01-01

Binding of tritiated 2,2,6,6-tetramethyl-4-piperidone-N-oxyl (/sup 3/H-TAN) to radiation-induced DNA-transients in E. coli K-12 strains AB 1157 and JO 307 rec A uvr A has been studied under in vivo conditions. After irradiation the cells were washed and resuspended in growth medium and left overnight at 37 deg C. Within an uncertainty of about 10 %, no effect of repair could be detected on the yield of TAN bound to DNA for any of the strains. During the period after resuspension TAN or fragments of TAN leaked out of the irradiated cell samples. This leakage may be attributed to semi-permanent association between TAN and radiation-induced radicals within the cell. The relevance of different interactions between TAN and transients in DNA is discussed.

CO2·- radical induced cleavage of disulfide bonds in proteins. A gamma-ray and pulse radiolysis mechanistic investigation

International Nuclear Information System (INIS)

Favaudon, V.; Tourbez, H.; Lhoste, J-M.; Houee-Levin, C.

1990-01-01

Disulfide bond reduction by the CO 2 ·- radical was investigated in aponeocarzinostatin, aporiboflavin-binding protein, and bovine immunoglobulin. Protein-bound cysteine free thiols were formed under γ-ray irradiation in the course of a pH-dependent and protein concentration dependent chain reaction. The chain efficiency increased upon acidification of the medium, with an apparent pK a around 5, and decreased abruptly below pH 3.6. It decreased also at neutral pH as cysteine accumulated. From pulse radiolysis analysis, CO 2 ·- proved able to induce rapid one-electron oxidation of thiols and of tyrosine phenolic groups in addition to one-electron donation to exposed disulfide bonds. The bulk rate constant of CO 2 ·- uptake by the native proteins was 5- to 10-fold faster at pH 3 than at pH 8, and the protonated form of the disulfide radical anion, appeared to be the major protein radical species formed under acidic conditions. Formation of the disulfide radical cation, phenoxyl radical Tyr-O · disproportionation, and phenoxyl radical induced oxidation of preformed thiol groups should also be taken into consideration to explain the fate of the oxygen-centered phenoxyl radical

Free radicals in pyrimidines: ESR of. gamma. -irradiated 5-cyclohexenyl-1,5-dimethyl barbituric acid. [/sup 60/Co

Energy Technology Data Exchange (ETDEWEB)

Benson, B. (Lehigh Univ., Bethlehem, PA); Erich, L.

1981-06-01

ESR studies have determined that ionizing radiation damage of hexobarbital (5-cyclohexenyl-1,5-dimethylbarbituric acid) causes the formation of a free radical (A) by hydrogen abstraction from the cyclohexenyl group. Hyperfine coupling tensors were determined for coupling of the unpaired electron to four protons. Visible light of wavelengths near 450 nm reversibly converts this radical to a second free radical (B) which also has the unpaired electron localized in the cyclohexenyl group. The activation energy for a thermally induced reverse conversion (B ..-->.. A) was determined to be 1.4 eV.

Inhibition of oxygen-dependent radiation-induced damage by the nitroxide superoxide dismutase mimic, tempol

International Nuclear Information System (INIS)

Mitchell, J.B.; DeGraff, W.; Kaufman, D.; Krishna, M.C.; Samuni, A.; Finkelstein, E.; Ahn, M.S.; Hahn, S.M.; Gamson, J.; Russo, A.

1991-01-01

Stable nitroxide radicals have been previously shown to function as superoxide dismutase (SOD)2 mimics and to protect mammalian cells against superoxide and hydrogen peroxide-mediated oxidative stress. These unique characteristics suggested that nitroxides, such as 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol), might protect mammalian cells against ionizing radiation. Treating Chinese hamster cells under aerobic conditions with 5, 10, 50, and 100 mM Tempol 10 min prior to X-rays resulted in radiation protection factors of 1.25, 1.30, 2.1, and 2.5, respectively. However, the reduced form of Tempol afforded no protection. Tempol treatment under hypoxic conditions did not provide radioprotection. Aerobic X-ray protection by Tempol could not be attributed to the induction of intracellular hypoxia, increase in intracellular glutathione, or induction of intracellular SOD mRNA. Tempol thus represents a new class of non-thiol-containing radiation protectors, which may be useful in elucidating the mechanism(s) of radiation-induced cellular damage and may have broad applications in protecting against oxidative stress

Correlation of the radioprotective effect of the methyl gallate on the ruptures induction in DNA and it effect in the capture of free radicals

International Nuclear Information System (INIS)

Morales R, P.; Cabral P, A.; Cruz V, V.L.; Gonzalez B, F.; Zarco M, A.

2007-01-01

It is shown in alive, the capacity of the methyl gallate to reduce the induced ruptures in the DNA for γ radiation. As well as to capture free radicals in a system in vitro. This suggests that the methyl gallate can be a radioprotector that acts capturing free radicals. (Author)

Wheat Germ Oil Attenuates Gamma Radiation- Induced Skeletal Muscles Damage in Rats

International Nuclear Information System (INIS)

Said, U.Z.; Saada, H.N.; Shedid, Sh.M.; Mahdy, E.M.E.; Shousha, W.Gh.

2008-01-01

Muscular strength is important in sport as well as in daily activities. Exposure to ionizing radiation is thought to increase oxidative stress and damage muscle tissue. Wheat germ oil is a natural unrefined vegetable oil. It is an excellent source of vitamin E, octacosanol, linoleic and linolenic essential fatty acids, which may be beneficial in neutralizing the free oxygen radicals. The present study was designed to investigate the efficacy of wheat germ oil, on radiation-induced oxidative damage in rats skeletal muscle. Wheat germ oil was supplemented orally via gavages to rats at a dose of 54 mg/ kg body weight/day for 14 successive days pre- and 7 post-exposure to 5 Gy (one shot dose) of whole body gamma irradiation. Animals were sacrificed 7, 14 and 21 days post radiation exposure. The results revealed that whole body gamma-irradiation of rats induces oxidative stress in skeletal muscles obvious by significant elevation in the level of thiobarbituric acid reactive substances (TBARS) associated with significant decreases in the content of reduced glutathione (GSE1), as well as decreases in superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities. Irradiated rats showed, also, significant decreases in creatine phosphokinase (CPK), glutamate dehydrogenase (GDH) and glucose-6-phosphate dehydrogenase (G-6-PD) activities. Furthermore, total iron, total copper and total calcium levels were significantly increased in skeletal muscles of irradiated rats group compared to control group. Wheat germ oil treated-irradiated rats showed significantly less sever damage and remarkable improvement in all the measured parameters, compared to irradiated rats. It could be concluded that wheat germ oil by attenuating radiation induced oxidative stress might play a role in maintaining skeletal muscle integrity

Radiation- induced aneuploidy in mammalian germ cells

International Nuclear Information System (INIS)

Tease, C.

1989-01-01

The ability of ionizing radiation to induce aneuploidy in mammalian germ cells has been investigated experimentally in the laboratory mouse using a variety of cytogenetic and genetic methods. These studies have provided unambiguous evidence of induced nondisjunction in both male and female germ cells when the effect of irradiation is screened in meiotic cells or preimplantation embryos. In contrast, however, cytogenetic analyses of post-implantation embryos and genetic assays for induced chromosome gains have not found a significant radiation effect. These apparently contradictory findings may be reconciled if (a) radiation induces tertiary rather than primary trisomy, or (b) induces embryo-lethal genetic damage, such as deletions, in addition to numerical anomalies. Either or both of these explanations may account for the apparent loss during gestation of radiation-induced trisomic embryos. Extrapolating from the information so far available, it seems unlikely that environmental exposure to low doses if low dose rate radiation will result in a detectable increase in the rate of aneuploidy in the human population. (author)

Coenzyme Q10 protects retinal cells from apoptosis induced by radiation in vitro and in vivo

International Nuclear Information System (INIS)

Lulli, M.; Witort, E.; Papucci, L.; Torre, E.; Schiavone, N.; Capaccioli, S.; Dal Monte, M.

2012-01-01

The key pathogenetic event of many retinopathies is apoptosis of retinal cells. Our previous studies have demonstrated that Coenzyme Q10 (CoQ10) prevents apoptosis of corneal keratocytes both in vitro and in vivo, by virtue of its ability to inhibit mitochondrial depolarization, independently of its free radical scavenger role. The aim of this study was to evaluate whether CoQ10 can protect cultured retinal cells and the retinas of rats from radiation-induced apoptosis, if instilled as eye drops in the cornea. In vitro experiments were carried out on cultured ARPE-19 or retinal ganglion cells (RGC)-5 cells pretreated with CoQ10 before eliciting apoptosis by ultraviolet (UV)- and γ-radiation, chemical hypoxia (Antimycin A) and serum starvation. Cell viability was evaluated by light microscopy and fluorescence activated cell sorting analysis. Apoptotic events were scored by time-lapse videomicroscopy. Mitochondrial permeability transition was evaluated by JC-1. The anti-apoptotic effectiveness of CoQ10 in retina was also evaluated by an in situ end-labeling assay in Wistar albino rats treated with CoQ10 eye drops prior to UV irradiation of the eye. CoQ10 substantially increased cell viability and lowered retinal cell apoptosis in response both to UV- and γ-radiation and to chemical hypoxia or serum starvation by inhibiting mitochondrion depolarization. In the rat, CoQ10, even when applied as eye drops on the cornea, protected all retina layers from ultraviolet radiation (UVR)-induced apoptosis. The ability of CoQ10 to protect retinal cells from radiation-induced apoptosis following its instillation on the cornea suggests the possibility for CoQ10 eye drops to become a future therapeutic countermeasure for radiation-induced retinal lesions. (author)

A challenge to mutation theory of radiation carcinogenesis

International Nuclear Information System (INIS)

Watanabe, Masami

2006-01-01

This paper presents an objection against the commonly accepted mutation theory in radiation carcinogenesis. First, author's studies of X-ray irradiated syrian hamster embryo (SHE) cells on malignant morphological changes and mutational change of HGPRT gene showed that the changing patterns were quite different, and as well, other studies in mice gave the essentially similar results. Thus radiation-induced carcinogenesis in cells does not simply occur by an accumulation of radiation-induced mutation. Second, as cultured cells usually used for oncogenesis studies already have the infinitively proliferative ability, the author used the primary cell culture obtained from the rodent embryo. Even those cells became immortal to be cancerous after repeated culture passage with the higher frequency of 10 3 -10 4 relative to somatic cell mutation. Cells thus seem to be easily changeable to cancerous ones. Bystander effect can cause transformation in non-irradiated cells and genetic instability by radiation can form the potentially unstable chromatin region, which induces telomere instability. The author has found that, while short-lived radicals yielded by X-ray irradiation attack DNA to induce cell death and chromosome aberration, long-lived radicals in biomolecules do not, but can cause mutation and carcinogenesis, which are reduced by vitamine C supplementation. The author concludes that the primary target in the radiation carcinogenesis in cells and even in the whole individuals is conceivably protein and not DNA. (T.I.)

Processing of free radical damaged DNA bases

International Nuclear Information System (INIS)

Wallace, S.

2003-01-01

while cells overexpressing one of the oxidative DNA glycosylases are radiosensitive. Human TK6 lymphoblastoid cells overexpressing the oxidative DNA glycosylases are also radiosensitive. Furthermore, both radioresistance and radiosensitivity correlated with the enzymatic production of double strand breaks produced after irradiation during attempted repair. Because these data indicated the potential harmful effects of the ordinarily beneficial presence of the oxidative DNA glycosylases after treatment of cells with ionizing radiation, it was of interest to see if the base excision repair enzymes were induced by ionizing radiation. We found that ionizing radiation does not induce the oxidative DNA glycosylases in either bacterial or in human TK6 lymphoblastoid cells. Interestingly, during this past year, three novel DNA glycosylases that recognize free radical-damaged bases have been identified. The characterization of these activities will also be discussed

Radiation-induced decomposition of trace amounts of 17 β-estradiol in water

International Nuclear Information System (INIS)

Kimura, Atsushi; Taguchi, Mitsumasa; Arai, Hidehiko; Hiratsuka, Hiroshi; Namba, Hideki; Kojima, Takuji

2004-01-01

The radiation-induced decomposition of trace amounts of 17 β-estradiol (E2) in water was studied as a function of the dose of 60 Co γ-rays. The rate constant of the reaction of the OH radicals with E2 was estimated to be 1.6x10 10 mol dm -3 s -1 by a comparison with the known rate constant for the reaction with phenol. Both E2 and E2-equivalent concentrations were estimated by LC-MS and ELISA, and decreased with an increase in γ-rays dose. E2 (1.8 nmol dm -3 ) in water was degraded almost completely by irradiations up to 10 Gy. The estrogen activity of the same sample solution still remained at a dose of 10 Gy, but decreased at 30 Gy to the lower than the threshold level of contamination to induce some estrogenic effects on the environmental ecology

Cytoprotective Mechanisms Mediated by Polyphenols from Chilean Native Berries against Free Radical-Induced Damage on AGS Cells

Directory of Open Access Journals (Sweden)

Felipe Ávila

2017-01-01

Full Text Available The prevalence of cytoprotective mechanisms induced by polyphenols such as activation of intracellular antioxidant responses (ICM and direct free radical scavenging was investigated in native Chilean species of strawberries, raspberries, and currants. Human gastric epithelial cells were co- and preincubated with polyphenolic-enriched extracts (PEEs from Chilean raspberries (Rubus geoides, strawberries (Fragaria chiloensis ssp. chiloensis f. chiloensis, and currants (Ribes magellanicum and challenged with peroxyl and hydroxyl radicals. Cellular protection was determined in terms of cell viability, glyoxalase I and glutathione s-transferases activities, and carboxymethyl lysine (CML and malondialdehyde levels. Our results indicate that cytoprotection induced by ICM was the prevalent mechanism for Rubus geoides and F. chiloensis. This agreed with increased levels of glyoxalase I and glutathione S-transferase activities in cells preincubated with PEEs. ORAC index indicated that F. chiloensis was the most efficient peroxyl radical scavenger. Moreover, ICM mediated by F. chiloensis was effective in protecting cells from CML accumulation in contrast to the protective effects induced by free radical scavenging. Our results indicate that although both polyphenol-mediated mechanisms can exert protective effects, ICM was the most prevalent in AGS cells. These results suggest a potential use of these native berries as functional food.

Radiation-induced camptocormia and dropped head syndrome. Review and case report of radiation-induced movement disorders

Energy Technology Data Exchange (ETDEWEB)

Seidel, Clemens; Kuhnt, Thomas; Kortmann, Rolf-Dieter; Hering, Kathrin [Leipzig University, Department of Radiotherapy and Radiation Oncology, Leipzig (Germany)

2015-10-15

In recent years, camptocormia and dropped head syndrome (DHS) have gained attention as particular forms of movement disorders. Camptocormia presents with involuntary forward flexion of the thoracolumbar spine that typically increases during walking or standing and may severely impede walking ability. DHS is characterized by weakness of the neck extensors and a consecutive inability to extend the neck; in severe cases the head is fixed in a ''chin to chest position.'' Many diseases may underlie these conditions, and there have been some reports about radiation-induced camptocormia and DHS. A PubMed search with the keywords ''camptocormia,'' ''dropped head syndrome,'' ''radiation-induced myopathy,'' ''radiation-induced neuropathy,'' and ''radiation-induced movement disorder'' was carried out to better characterize radiation-induced movement disorders and the radiation techniques involved. In addition, the case of a patient developing camptocormia 23 years after radiation therapy of a non-Hodgkin's lymphoma of the abdomen is described. In total, nine case series of radiation-induced DHS (n = 45 patients) and - including our case - three case reports (n = 3 patients) about radiogenic camptocormia were retrieved. Most cases (40/45 patients) occurred less than 15 years after radiotherapy involving extended fields for Hodgkin's disease. The use of wide radiation fields including many spinal segments with paraspinal muscles may lead to radiation-induced movement disorders. If paraspinal muscles and the thoracolumbar spine are involved, the clinical presentation can be that of camptocormia. DHS may result if there is involvement of the cervical spine. To prevent these disorders, sparing of the spine and paraspinal muscles is desirable. (orig.) [German] In den letzten Jahren haben Bewegungsstoerungen von Wirbelsaeule und paraspinaler Muskulatur in

The experimental study on protective effects and mechanisms of chelating agents of catechols amino carboxylic acid for radiation injury induced by actimides(Th-234)

International Nuclear Information System (INIS)

Chen, H. H.; Luo, M. C.; Sun, M. Z.; Hu, Y. X.; Wang, Y. H.; Jin, M. Y.; Cheng, W. Y.

2002-01-01

The decorporative efficacy and antioxidative action of prompt and delayed consecutive administration of catecholicpolyaminopolycarboxylate ligands, 7601 and 9501 for radiothorium in mice were investigated. DTPA and Vitamin E were used as positive controls. The competitive abilities of 7601 and 9501 to mobilize the thorium with BSA were studied. Their inhibition effects on superoxide anionas radicals were measured with electron spin resonance. The results showed that 7601 and 9501 are able to effectively prevent the internal radiation injury induced radiothorium, attributing to their double functions of pronounced removal effectiveness and antioxidative action. Their protective effects were better than DTPA and Vitamin E. The mechanisms of protective effects of 7601 and 9501 for internal radiation injury was close related to competitive ability of chelating agent to chelate the thorium with BSA and oxygen free radical scavenging activities

Mechanisms for radiation damadge in DNA

International Nuclear Information System (INIS)

Sevilla, M.D.

1994-11-01

A comprehensive report is provided of the author's research since 1986 on radiolysis of DNA as well as current state of knowledge in this area. In particular study areas such as the influence of hydration on the absolute yield of primary ionic free radicals in irradiated DNA at 77K, Ab Initio molecular orbital calculations of DNA base pairs and their radical ions, and radiation-induced DNA damage as a function of hydration are discussed

Protective Role of Alpha Lipoic Acid Against Disorders Induced by Gamma Radiation

International Nuclear Information System (INIS)

Abd El Azeem, Kh.N.M.

2011-01-01

Ionizing radiation interacts with living cells, causing a variety of biochemical changes depending on exposed and absorbed doses, duration of exposure, interval after exposure and susceptibility of tissues to ionizing radiation. So, it may increase the oxidative stress and damage of body organs. Alpha-lipoic acid (ALA-also known as thioctic acid) appears to be readily absorbed from an oral dose and converts easily to its reduced form, dihydro lipoic acid (DHLA), in many tissues of the body. ALA can neutralize free radicals in both fatty and watery regions of cells. The present study has been designed to evaluate the possible efficiency of ALA as antioxidant and radio-protector against radiation induced oxidative stress in different organs (liver, kidney and heart) in rats through estimation of the activity of markers of serum liver, kidney and heart function, in addition to the histopathological differentiation of these organs by light and electron microscope. Five equal groups were conducted for the study: control, ALA (30 mg/kg body wt), irradiated (each rat was exposed to 6 Gy as a fractionated dose of gamma (γ) radiation), irradiated plus ALA (each rat received ALA for 9 days simultaneously during exposure) and ALA plus irradiation plus ALA groups (each rat received ALA for a week pre-exposure plus 9 days during exposure). Radiation doses were fractionated dose levels of 2 Gy each 3 days to reach accumulative dose of 6 Gy. After 3 days of each exposure rats were sacrificed, except, those left for recovery test one month after last exposure. The results revealed that whole body γ-irradiation of rats induces oxidative stress in liver, kidney and heart obviously manifested by significant elevation in alanine and aspartate transaminase ( ALT and AST), alkaline phosphatase (ALP), urea, creatinine and creatine kinase (CK-MB). ALA treated-irradiated rats showed lower significantly values indicating remarkable improvement in all measured parameters and

Radiation chemistry of aromatic dimer radical cations

International Nuclear Information System (INIS)

Okamoto, Kazumasa; Tagawa, Seiichi

2009-01-01

π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

Radiation-induced myelopathy

Energy Technology Data Exchange (ETDEWEB)

Gaenshirt, H [Heidelberg Univ. (F.R. Germany). Neurologische Klinik

1975-10-01

12 cases of radiation-induced myelopathy after /sup 60/Co teletherapy are reported on. Among these were 10 thoracal lesions, one cerviothoracal lesion, and one lesion of the medulla oblongata. In 9 cases, Hodgkin's disease had been the primary disease, tow patients had been irradiated because of suspected vertebral metastases of cancer of the breast, and one patient had suffered from a glomus tumour of the petrous bone. The spinal doses had exceeded the tolerance doses recommended in the relevant literature. There was no close correlation between the radiation dose and the course of the disease. The latency periods between the end of the radiotherapy and the onset of the neurological symptons varied from 6 to 16 mouths and were very constant in 7 cases with 6 to 9 months. The segmental height of the lesion corresponded to the level of irradiation. The presenting symptons of radiation-induced myelopathy are buruing dysaesthesias and Brown-Sequard's paralysis which may develop into transverse lesion of the cord with paraplegia still accompanied by dissociated perception disorders. The disease developed intermittently. Disturbances of the bladder function are frequent. The fluid is normal in most cases. Myelographic examinations were made in 8 cases. 3 cases developed into stationary cases exhibiting. Brown-Sequard syndrome, while 9 patients developed transverse lesion of the cord with paraplegia. 3 patients have died; antopsy findings are given for two of these. In the pathogenesis of radiation-induced myelopathy, the vascular factor is assumed to be of decisive importance.

Loss of covalently linked lipid as the mechanism for radiation-induced release of membrane-bound polysaccharide and exonuclease from Micrococcus radiodurans

International Nuclear Information System (INIS)

Mitchel, R.E.J.

1981-01-01

The mechanism of γ-radiation-induced release of polysaccharide and exonuclease from the midwall membrane of Micrococcus radiodurans has been examined. These two components appear to be released independently, but by very similar processes. Direct analysis of radiation-released polysaccharide indicated the absence of an alkali-labile neutral lipid normally present in the native material. Radiation-induced release therefore probably results from the radiolytic cleavage of a covalently linked lipid which normally serves to anchor these substances to the membrane. The absence of a natural membrane-bound carotenoid had no effect on the rate of release of these components. Likewise, the absence of exonuclease in an exonuclease minus mutant did not influence the release of polysaccharide. It is suggested that the major pathway of radical transfer from the initiating .OH and culminating in the cleavage of the neutral lipid anchor may not be via the membrane

Radiation sensitivity of different citric pectins

Energy Technology Data Exchange (ETDEWEB)

Inamura, Patricia Y.; Mastro, Nelida L. del [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: patyoko@yahoo.com; nlmastro@ipen.br

2007-07-01

Pectic substances are important soluble polysaccharides of plant origin of considerable interest for food industry as gelling agent and stabilizer in jams, fruit jellies, yogurt drinks and lactic acid beverages. Polysaccharides can be degraded by ionizing radiation due to the free radical induced scission of the glycosidic bonds. Viscosity methods had been used to determine the efficiency of hydroxyl radical induced chain breaks generation in macromolecules. In the present work samples of pectin with different degree of methoxylation were employed in order to study their radiation sensitivity by means of viscosity measurements. Samples of citric pectin 1% solutions were irradiated with gamma rays at different doses, ranging from 0 to 15 kGy, using a {sup 60}Co Gammacell 220 (AECL), dose rate about 2 kGy/h. After irradiation the viscosity was measured on the viscometer Brookfield model LV-DVIII at 50, 60 and 70 deg C within a period of 48h. Pectin viscosity with high degree of methoxylation decreased sharply with the radiation dose remaining almost constant from 10 kGy. Pectin with low degree of methoxylation presented initially higher values of viscosity and the radiation induced decrease was also pronounced. Viscosity measurements decreased with the increase of the temperature applied for both kind of samples. The effect of radiation induced chain breaks generation in pectin molecules was evident through the viscosity reduction of irradiated pectin solutions although the viscosity presented diverse values depending of the degree of methoxylation of carboxyl groups in the backbone of polysaccharide macromolecules. (author)

Radiation sensitivity of different citric pectins

International Nuclear Information System (INIS)

Inamura, Patricia Y.; Mastro, Nelida L. del

2007-01-01

Pectic substances are important soluble polysaccharides of plant origin of considerable interest for food industry as gelling agent and stabilizer in jams, fruit jellies, yogurt drinks and lactic acid beverages. Polysaccharides can be degraded by ionizing radiation due to the free radical induced scission of the glycosidic bonds. Viscosity methods had been used to determine the efficiency of hydroxyl radical induced chain breaks generation in macromolecules. In the present work samples of pectin with different degree of methoxylation were employed in order to study their radiation sensitivity by means of viscosity measurements. Samples of citric pectin 1% solutions were irradiated with gamma rays at different doses, ranging from 0 to 15 kGy, using a 60 Co Gammacell 220 (AECL), dose rate about 2 kGy/h. After irradiation the viscosity was measured on the viscometer Brookfield model LV-DVIII at 50, 60 and 70 deg C within a period of 48h. Pectin viscosity with high degree of methoxylation decreased sharply with the radiation dose remaining almost constant from 10 kGy. Pectin with low degree of methoxylation presented initially higher values of viscosity and the radiation induced decrease was also pronounced. Viscosity measurements decreased with the increase of the temperature applied for both kind of samples. The effect of radiation induced chain breaks generation in pectin molecules was evident through the viscosity reduction of irradiated pectin solutions although the viscosity presented diverse values depending of the degree of methoxylation of carboxyl groups in the backbone of polysaccharide macromolecules. (author)

Radiation damage in solid 5-halouracils. Electron spin resonance of single crystals of 5-bromouracil

International Nuclear Information System (INIS)

Oloff, H.; Huettermann, J.; Symons, M.C.R.

1978-01-01

Knowledge gained about halogen hyperfine interaction in radiation-induced free radicals formed at 300 K in a variety of 5-halouracil bases, together with the availability of crystal structure of 5-bromouracil aids in determination of the dominant radical structure. Details of its spectral parameters are presented, ESR spectra of single crystals of 5-bromouracil irradiated at 300K induce the presence of free radicals which indicate the loss of hydrogen from N 1 , confirming structure I as the dominant radical. The powder spectrum of 5-bromouracil measured after irradiation at 300K shows x features of radical I, but they appear superimposed by lines of another radical also involving bromine hyperfine interaction. These lines most probably belong to the hydrogen-addition radical II

Study on radiation-inducible genes

Energy Technology Data Exchange (ETDEWEB)

Lim, Sang Yong; Kim, Dong Ho; Joe, Min Ho; Park, Hae Jun; Song, Hyu Npa

2012-01-15

Radiation-inducible genes of E. coli, which is a model strain for bacterial study, and Salmonella, which is a typical strain for pathogenic bacteria were compared through omic analysis. Heat shock response genes and prophage genes were induced by radiation in Salmonella, not in E. coli. Among prophage genes tested, STM2628 showed the highest activation by radiation, and approximately 1 kb promoter region was turned out to be necessary for radiation response. To screen an artificial promoter showing activation by 2 Gy, the high-throughput screening method using fluorescent MUG substrate was established. The use of bacteria as anticancer agents has attracted interest. In this study, we tried to develop tumor targeting bacteria in which the radiation-inducible promoter activate a transgene encoding a cytotoxic protein. To do this, a tumor-targeting hfq Salmonella mutant strain was constructed, and we found that its virulence decreased. For outward secretion of anticancer protein produced inside bacteria, the signal peptide of SspH1 was determined and the signal peptide was proven to be able to secrete an anticancer protein. Tumor xenograft mouse model was secured, which can be used for efficiency evaluation of bacterial tumor therapy.

Study on radiation-inducible genes

International Nuclear Information System (INIS)

Lim, Sang Yong; Kim, Dong Ho; Joe, Min Ho; Park, Hae Jun; Song, Hyu Npa

2012-01-01

Radiation-inducible genes of E. coli, which is a model strain for bacterial study, and Salmonella, which is a typical strain for pathogenic bacteria were compared through omic analysis. Heat shock response genes and prophage genes were induced by radiation in Salmonella, not in E. coli. Among prophage genes tested, STM2628 showed the highest activation by radiation, and approximately 1 kb promoter region was turned out to be necessary for radiation response. To screen an artificial promoter showing activation by 2 Gy, the high-throughput screening method using fluorescent MUG substrate was established. The use of bacteria as anticancer agents has attracted interest. In this study, we tried to develop tumor targeting bacteria in which the radiation-inducible promoter activate a transgene encoding a cytotoxic protein. To do this, a tumor-targeting hfq Salmonella mutant strain was constructed, and we found that its virulence decreased. For outward secretion of anticancer protein produced inside bacteria, the signal peptide of SspH1 was determined and the signal peptide was proven to be able to secrete an anticancer protein. Tumor xenograft mouse model was secured, which can be used for efficiency evaluation of bacterial tumor therapy

Radiation-induced cancers in man

International Nuclear Information System (INIS)

Hirose, Fumio

1978-01-01

Radiation-induced cancers in man were divided into three groups, a group in which cancers occurred after atomic bomb exposure, a group in which cancers occurred in radiologists and other medical specialists, and a group in which cancers occurred after exposure to diagnostic radiation, and they were summarized. In atomic bomb survivors leukemia, thyroid cancer, salivary gland cancer, lung cancer, and breast cancer occurred so frequently. In addition to them, mortality ratios by malignant lymphoma, stomach cancer, esophageal cancer, and by cancer of urinary tract were increased. The incidence of leukemia was decreased in those who treated radiation owing to the development of the protection of occupational exposure, and the incidence of radiation-induced cancers was decreased in patients owing to the improvement of therapy. However, a new problem has arisen as to the occurrence of cancers after medical exposure, such as various histological types of cancers after the treatment of skin diseases on the head, and breast cancer after the treatment of pneumothorax. Dose-to-effect relation, hereditary factors, effect of age, immunological influences and endocrine actions were also studied in each radiation-induced cancer. (Ichikawa, K.)

Radiation-induced cancers in man

Energy Technology Data Exchange (ETDEWEB)

Hirose, F [Hiroshima Univ. (Japan). Research Inst. for Nuclear Medicine and Biology

1978-07-01

Radiation-induced cancers in man were divided into three groups, a group in which cancers occurred after atomic bomb exposure, a group in which cancers occurred in radiologists and other medical specialists, and a group in which cancers occurred after exposure to diagnostic radiation, and they were summarized. In atomic bomb survivors leukemia, thyroid cancer, salivary gland cancer, lung cancer, and breast cancer occurred so frequently. In addition to them, mortality ratios by malignant lymphoma, stomach cancer, esophageal cancer, and by cancer of urinary tract were increased. The incidence of leukemia was decreased in those who treated radiation owing to the development of the protection of occupational exposure, and the incidence of radiation-induced cancers was decreased in patients owing to the improvement of therapy. However, a new problem has arisen as to the occurrence of cancers after medical exposure, such as various histological types of cancers after the treatment of skin diseases on the head, and breast cancer after the treatment of pneumothorax. Dose-to-effect relation, hereditary factors, effect of age, immunological influences and endocrine actions were also studied in each radiation-induced cancer.

Free radicals generated by radiolysis of aqueous solutions

International Nuclear Information System (INIS)

Schwarz, H.A.

1981-01-01

The free radicals produced in the radiolysis of aqueous solutions span the range of redox potentials from -2.9 to +2.65 volts. The identity and nature of these radicals were discussed. Most of the discussion was results obtained with low LET radiation sources ( 60 Co gamma radiation or electron accelerators). Water radiolysis provides the synthesis of many radicals and radical ions in aqueous solution. The primary radicals, e/sub aq/ - H, OH, are well characterized. The radical population can be made to be 90% pure OH (or O - ) if N 2 O solutions are irradiated, the remaining 10% being H atoms. 55% of the radicals can be converted to H atoms in acid solution or in neutral phosphate solutions(e/sub aq/ - reacts with H 2 PO 4- to produce H). The remaining 45% (OH radicals) are difficult to convert to H by reaction with H 2 , due to the slow rate of the reaction. About 100 atmospheres of H 2 are required to do the conversion in less than 10 - 6 sec. 3 figures, 3 tables. (DP)

Facile graft polystyrene onto multi-walled carbon nanotubes via in situ thermo-induced radical polymerization

International Nuclear Information System (INIS)

Liu Peng

2009-01-01

A facile procedure was developed for the grafting of polystyrene onto the surfaces of multi-walled carbon nanotubes (MWNTs) via the in situ thermo-induced bulk radical polymerization of styrene at the different polymerizing temperatures, in the presence of MWNTs without any initiator added. The grafting products were validated by the dispersibility, TEM, TGA, FT-IR, and Raman analysis. The TGA results also showed the lower polymerizing temperature was propitious to the free radical addition reactions.

Radiation-induced brain injury: A review

Directory of Open Access Journals (Sweden)

Michael eRobbins

2012-07-01

Full Text Available Approximately 100,000 primary and metastatic brain tumor patients/year in the US survive long enough (> 6 months to experience radiation-induced brain injury. Prior to 1970, the human brain was thought to be highly radioresistant; the acute CNS syndrome occurs after single doses > 30 Gy; white matter necrosis occurs at fractionated doses > 60 Gy. Although white matter necrosis is uncommon with modern techniques, functional deficits, including progressive impairments in memory, attention, and executive function have become important, because they have profound effects on quality of life. Preclinical studies have provided valuable insights into the pathogenesis of radiation-induced cognitive impairment. Given its central role in memory and neurogenesis, the majority of these studies have focused on the hippocampus. Irradiating pediatric and young adult rodent brains leads to several hippocampal changes including neuroinflammation and a marked reduction in neurogenesis. These data have been interpreted to suggest that shielding the hippocampus will prevent clinical radiation-induced cognitive impairment. However, this interpretation may be overly simplistic. Studies using older rodents, that more closely match the adult human brain tumor population, indicate that, unlike pediatric and young adult rats, older rats fail to show a radiation-induced decrease in neurogenesis or a loss of mature neurons. Nevertheless, older rats still exhibit cognitive impairment. This occurs in the absence of demyelination and/or white matter necrosis similar to what is observed clinically, suggesting that more subtle molecular, cellular and/or microanatomic modifications are involved in this radiation-induced brain injury. Given that radiation-induced cognitive impairment likely reflects damage to both hippocampal- and non-hippocampal-dependent domains, there is a critical need to investigate the microanatomic and functional effects of radiation in various brain

Evaluation of the compatibility induced by ionizing radiation on polymeric blends

International Nuclear Information System (INIS)

Pino, Eddy S.; Machado, Luci D.B.; Feitosa, Marcos A.F.; Giovedi, Claudia

2011-01-01

To produce new polymers is a costly and time consuming task. Therefore, the utilization of existing polymers in form of blends enables to obtain new polymeric materials at a competitive cost. In this sense, polymer blending has become a growing scientific and commercial development activity. In most of the cases, polymeric blends have immiscible components and this represents an unbecoming situation on blend design. For such immiscible blends, it is required the use of compatibilizers to gain properties advantage. Compatibilization process can be achieved by chemical handling using additives and heat. On the other hand, ionizing radiation induces compatibilization by free radicals, which improve the dispersion and adhesion of the blend phases, without use of chemical additives and at room temperature. In this work, a polyamide 6.6/low-density polyethylene 75/25% wt/wt composition blend was electron beam irradiated up to 250 kGy, and thereafter mechanical tests were carried out. Tensile measurements have shown that the strength at break increases, the elongation at break decreases, the resistance to impact decreases and hardness increases when the radiation dose increases. Since this mechanical behavior is due to cross-linking and to the radiation induced blend compatibilization, this compatibility was evaluated by the approach of the glass transition temperatures for both components using DMA measurements. The results have shown that the glass transition temperatures of the blend components got closer in 8 deg C in the irradiated sample, when compared to the glass transition temperature values obtained for non-irradiated blend. (author)

Evaluation of the compatibility induced by ionizing radiation on polymeric blends

Energy Technology Data Exchange (ETDEWEB)

Pino, Eddy S.; Machado, Luci D.B., E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Feitosa, Marcos A.F. [Centro Paula Souza, Faculdade de Tecnologia da Zona Leste, Sao Paulo, SP (Brazil); Giovedi, Claudia, E-mail: claudia.giovedi@ctmsp.mar.mil.b [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil). Dept. de Tecnologia de Reatores Nucleares

2011-07-01

To produce new polymers is a costly and time consuming task. Therefore, the utilization of existing polymers in form of blends enables to obtain new polymeric materials at a competitive cost. In this sense, polymer blending has become a growing scientific and commercial development activity. In most of the cases, polymeric blends have immiscible components and this represents an unbecoming situation on blend design. For such immiscible blends, it is required the use of compatibilizers to gain properties advantage. Compatibilization process can be achieved by chemical handling using additives and heat. On the other hand, ionizing radiation induces compatibilization by free radicals, which improve the dispersion and adhesion of the blend phases, without use of chemical additives and at room temperature. In this work, a polyamide 6.6/low-density polyethylene 75/25% wt/wt composition blend was electron beam irradiated up to 250 kGy, and thereafter mechanical tests were carried out. Tensile measurements have shown that the strength at break increases, the elongation at break decreases, the resistance to impact decreases and hardness increases when the radiation dose increases. Since this mechanical behavior is due to cross-linking and to the radiation induced blend compatibilization, this compatibility was evaluated by the approach of the glass transition temperatures for both components using DMA measurements. The results have shown that the glass transition temperatures of the blend components got closer in 8 deg C in the irradiated sample, when compared to the glass transition temperature values obtained for non-irradiated blend. (author)

Sulfite-induced protein radical formation in LPS aerosol-challenged mice: Implications for sulfite sensitivity in human lung disease

Directory of Open Access Journals (Sweden)

Ashutosh Kumar

2018-05-01

Full Text Available Exposure to (bisulfite (HSO3– and sulfite (SO32– has been shown to induce a wide range of adverse reactions in sensitive individuals. Studies have shown that peroxidase-catalyzed oxidation of (bisulfite leads to formation of several reactive free radicals, such as sulfur trioxide anion (.SO3–, peroxymonosulfate (–O3SOO., and especially the sulfate (SO4. – anion radicals. One such peroxidase in neutrophils is myeloperoxidase (MPO, which has been shown to form protein radicals. Although formation of (bisulfite-derived protein radicals is documented in isolated neutrophils, its involvement and role in in vivo inflammatory processes, has not been demonstrated. Therefore, we aimed to investigate (bisulfite-derived protein radical formation and its mechanism in LPS aerosol-challenged mice, a model of non-atopic asthma. Using immuno-spin trapping to detect protein radical formation, we show that, in the presence of (bisulfite, neutrophils present in bronchoalveolar lavage and in the lung parenchyma exhibit, MPO-catalyzed oxidation of MPO to a protein radical. The absence of radical formation in LPS-challenged MPO- or NADPH oxidase-knockout mice indicates that sulfite-derived radical formation is dependent on both MPO and NADPH oxidase activity. In addition to its oxidation by the MPO-catalyzed pathway, (bisulfite is efficiently detoxified to sulfate by the sulfite oxidase (SOX pathway, which forms sulfate in a two-electron oxidation reaction. Since SOX activity in rodents is much higher than in humans, to better model sulfite toxicity in humans, we induced SOX deficiency in mice by feeding them a low molybdenum diet with tungstate. We found that mice treated with the SOX deficiency diet prior to exposure to (bisulfite had much higher protein radical formation than mice with normal SOX activity. Altogether, these results demonstrate the role of MPO and NADPH oxidase in (bisulfite-derived protein radical formation and show the involvement of

Free radical production by high energy shock waves--comparison with ionizing irradiation.

Science.gov (United States)

Morgan, T R; Laudone, V P; Heston, W D; Zeitz, L; Fair, W R

1988-01-01

Fricke chemical dosimetry is used as an indirect measure of the free radical production of ionizing irradiation. We adapted the Fricke ferrous sulfate radiation dosimeter to examine the chemical effects of high energy shock waves. Significant free radical production was documented. The reaction was dose dependent, predictably increased by acoustic impedance, but curvilinear. A thousand shocks at 18 kilovolts induced the same free radical oxidation as 1100 rad cobalt-60 gamma ionizing irradiation, increasing to 2900 rad in the presence of an air-fluid zone of acoustic impedance. The biological effect of these free radicals was compared to that of cobalt-60 ionizing irradiation by measuring the affect on Chinese hamster cells by clonogenic assay. While cobalt-60 irradiation produced a marked decrease in clonogenic survivors, little effect was noted with high energy shock waves. This suggested that the chemical effects produced by shock waves were either absent or attenuated in the cells, or were inherently less toxic than those of ionizing irradiation.

EPR of free radicals in solids II trends in methods and applications

CERN Document Server

Lund, Anders; Lund, Anders

2012-01-01

EPR of Free Radicals in Solids: Trends in Methods and Applications, 2nd ed. presents a critical two volume review of the methods and applications of EPR (ESR) for the study of free radical processes in solids. Emphasis is on the progress made in the developments in EPR technology, in the application of sophisticated matrix isolation techniques and in the advancement in quantitative EPR that have occurred since the 1st edition was published. Improvements have been made also at theoretical level, with the development of methods based on first principles and their application to the calculation of magnetic properties as well as in spectral simulations. EPR of Free Radicals in Solids II focuses on the trends in applications of experimental and theoretical methods to extract structural and dynamical properties of radicals and spin probes in solid matrices by continuous wave (CW) and pulsed techniques in nine chapters written by experts in the field. It examines the studies involving radiation- and photo-induced in...

Modification of Natural Polymers by Radiation-Induced Processing for Versatile Applications

International Nuclear Information System (INIS)

Nagasawa, N.; Hiroki, A.; Tamada, M.

2010-01-01

Radiation-crosslinking mechanism of polysaccharide derivatives such as carboxymethyl cellulose (CMC), carboxymethyl chitosan (CMCts) is not clarified yet. Radicals in CMC formed by reaction with OH radical were studied by ESR in order to elucidate the radiation-crosslinking mechanism of CMC. ESR spectra implied that radicals were created on carboxymethyl groups linked to C2, C3 and C6 of glucose unit in CMC. The radicals of CMCts were also created on carboxymethyl groups linked to C3 and C6 of glusamine unit. For application of carboxymethyl cellulose (CMC) to a super water-adsorbent, gel fraction should be adjusted to the range of 50%. It was found that gel fraction of CMC could be control by the irradiation temperature of CMC aqueous paste-like state. Poly(L-lactic acid)(PLLA) could be crosslinked when it was irradiated with coexistence of crosslinker, triallyl isocyanurate. However, the crosslinked PLLA is thermally deformed under the stress at 70 °C. The thermo mechanical stability of PLLA was further improved by the adding SiO 2 and the post heating at 90 °C. The storage modulus of the treated PLLA showed about 100 times higher than that of only crosslinked PLLA. The improved materials was applied to demonstration lens of eyewear. (author)

The radiation-induced copolymerization of vinyl acetate with dibutyl maleate

International Nuclear Information System (INIS)

Du Plessis, T.A.; Lustig, A.

1975-01-01

The radiation-induced copolymerization of vinyl acetate with dibutyl maleate was investigated in the temperature range from -50 0 to 90 0 . A copolymer of the unsaturated ester with vinyl acetate was obtained in which the comonomers alternate with regularity along the polymer chain over the entire range of comonomer compositions and temperature range investigated. Both the rate of copolymerization and the molecular weight of the resulting copolymer were found to depend strongly on the comonomer composition. The monomer reactivity ratios were found to be practically zero. The apparent activation energy was found to change at 5 0 with an increase in temperature from a value of 1,6 kcal/mole to a value of 4,4kcal/mole. Scavenger studies indicate that a free radical mechanism prevails over the entire temperature range investigated. (Author) [af

Ionizing radiation induced malignancies in man

International Nuclear Information System (INIS)

Dutrillaux, B.

1997-01-01

Using data on gene and chromosome alterations in human cancers, it is proposed that most radiation induced cancers are a consequence of recessive mutations of tumor suppressor genes. This explains the long delay between radiation exposure and the cancer onset. As a consequence, radiation induced cancers belong to groups of tumors where no specific translocations (forming or activating oncogenes) but multiple unbalanced chromosome rearrangements (deletions unmasking recessive mutations) exist. This explains why osteosarcomas, malignant fibrous histiocytoma, chondrosarcomas are frequently induced, but not liposarcoma, Ewing sarcomas and rhabdomyosarcomas, among others. A single exception confirms this rule: papillary thyroid cancer, frequently induced in exposed children, in which structural rearrangements frequently form a RET/PTC3 fusion gene. This fusion gene is the results of the inversion of a short segment of chromosome 10, and it is assumed that such rearrangement (small para-centric inversion) can easily occur after exposure to radiations, at contrast with translocations between to genes belonging to different chromosomes. (author)

EPR assessment of the free radicals in irradiated foodstuffs

International Nuclear Information System (INIS)

Tencheva, S.; Katsareva, Ts.; Malinovski, A.; Kabasanov, K.

1985-01-01

In the hygienic assessment of radiation treated foodstuffs the study of free radicals formed during radiation exposure, their concentration and disintegration kinetics are of particular interest. In the work presented the concentration of the free radicals in irradiated prunes, nuts and corn is determined using EPR spectroscopy. The following doses are applied: 2, 10 and 20 kGy for prunes, 1, 10 and 20 kGy for nuts, and 0.75, 10 and 20 kGy for corn. EPR measurements are done immediately after the irradiation: 24 hours, and 3, 6, 9 and 15 days after the exposure. In the small radiation doses the formation of single radicals is observed. In doses of 10 kGy the spectra get complicated with the occurence of radicals R 1 , R 2 , R 3 and R 4 . The assessment of radicals proves to be a prospective method for the identification and determination of the preservation terms of foodstuffs

The Use of Radiation-Induced Degradation in Controlling Molecular Weights of Polysaccharides : The Effect of Humidity

International Nuclear Information System (INIS)

Sen, M.

2006-01-01

Better understanding of chemistry of radiation-induced degradation is becoming of increasing importance on account of the utilization of polymeric materials in a variety of radiation environments as well as beneficial uses of degraded polymers. It is very well known that polysaccharides in dry form or in solution degrade when exposed to ionizing radiation. In this study degrading effect of radiation has been considered from the point of view of controlling the molecular weights of kappa- and iota-carrageenans and sodium alginate irradiated under varying environmental conditions. The humidity equilibrated polymer samples kept over saturated aqueous salt solutions of NaCl, NaNO 3 and MgCl 2 were irradiated in a Gammacell 220 at room temperature. The degradation was investigated in detail by a careful Gel Permeation Chromatographic analysis of their respective molecular weights before and after irradiation Alexander-Charlesby-Ross equation was used in determining their radiation-chemical yields. Degradation yield is the highest for dry irradiated kappa- (G(S) = 0.73) and iota-carrageenans (G(S) = 2.43) and with small amount of water taken up from surrounding humidity degradation becomes less pronounced and G(S) values show a decrease down to G(S) = 0.16 and 0.87 at 75 % relative humidity, respectively. At very high water contents degradation effect again becomes more effective. Sodium alginate has fount to be less sensitive to the effect of humidity. When there is small amount of water in the polysaccharide structure, it is unlikely to expect an indirect effect of radiation. The water located in between the polymer chains however can give enough mobility to kappa and iota karrageenans chains, plastifying effect, which may enhance the radical-radical combinations thus lowering the rate of degradation hence reducing G(S) values

Three cases of radiation-induced cancer in oral regions

International Nuclear Information System (INIS)

Kawamura, Hiroshi; Shinoki, Kunihiko; Endo, Yoshitaka; Fujita, Yasushi; Hayashi, Susumu

1985-01-01

Three cases of radiation-induced cancer in the oral regions were reported with relation to radiation therapy. One was the general radiation-induced cancer following radiotherapy for the hemangioma. The other two cases, which belonged in the B-1 group of Sakai and his coworker's diagnostic criteria for radiation-induced cancer, were those occurring after radiotherapy for the malignant tumors. Due to the relatively high dosage exposure by the patient in the radiotherapy it is necessary to look out the latency of the radiation-induced cancer. After radiotherapy, careful and periodical observation is important for immediate treatment in an early stage for the radiation-induced cancer to have a favorable prognosis. In addition careful observation of the changes after radiotherapy helps in discovering the precancerous lesions from the therapy. For the radiation-induced cancer, surgical treatment would be the best, however, radiation therapy is also effective in certain cases. (author)

Ion microbeam irradiation for radiobiology and radical chemistry: status and prospect

Energy Technology Data Exchange (ETDEWEB)

Khodja, H, E-mail: hicham.khodja@cea.fr [CEA, IRAMIS, SIS2M, LEEL, 91191 Gif-sur-Yvette (France); CNRS, UMR 3299, SIS2M, LEEL, 91191 Gif-sur-Yvette (France)

2011-01-01

Ion microbeams are commonly used to study local irradiation effects in living cells, as it has been established that ion beam irradiations can lead to deleterious changes in cells that are not struck directly by the microbeam. Such changes, which take place over distances long compared to the size of the irradiation spot and for times long compared to the time of irradiation, are collectively termed radiation-induced bystander effect or RIBE. Free-radical chemistry is frequently invoked to explain the RIBE but no unified model is available at present. Ion microbeams when coupled with advanced methods for observing free radicals are the tools of choice for investigating the chemistry and biological processes governing RIBE.

Effect of edaravone on radiation-induced brain necrosis in patients with nasopharyngeal carcinoma after radiotherapy: a randomized controlled trial.

Science.gov (United States)

Tang, Yamei; Rong, Xiaoming; Hu, Weihan; Li, Guoqian; Yang, Xiaoxia; Yang, Jianhua; Xu, Pengfei; Luo, Jinjun

2014-11-01

Excessive generation of free radicals plays a critical role in the pathogenesis of radiation-induced brain injury. This study was designed to evaluate the protective effect of edaravone, a free radical scavenger, on radiation-induced brain necrosis in patients with nasopharyngeal carcinoma. Eligible patients were randomized 1:1 to the control group and the edaravone group (intravenous 30 mg twice per day for 2 weeks). Both groups received intravenous conventional steroid therapy and were monitored by brain MRI and LENT/SOMA scales prior to the entry of the trial and at 3-months after completing the trial. The primary end point was a 3-month response rate of the proportional changes determined by MRI. The trial is registered at Clinicaltrials.gov Identifier: NCT01865201. Between 2009 and 2012, we enrolled 154 patients. Of whom 137 were eligible for analysis. The volumes of necrosis estimated on T(2)-weighted image showed that 55.6 % edaravone-treated patients (40 out of 72) showed edema decreases ≥25 %, which was significantly higher than that in the control group (35.4 %, 23 out of 65, p = 0.025). Forty-four patients treated with edaravone (61.1 %) reported improvement in neurologic symptoms and signs evaluated by LENT/SOMA scales, while the rate was 38.5 % in the control group (p = 0.006). MRI of the edaravone group showed a significant decrease in area of T(1)-weighted contrast enhancement (1.67 ± 4.69 cm(2), p = 0.004) and the T(2)-weighted edema (5.08 ± 10.32 cm(2), p = 0.000). Moreover, compared with those in control group, patients with edaravone exhibited significantly better radiological improvement measured by T(2)-weighted image (p = 0.042). Administration of edaravone, in adjunct to steroid regimen, might provide a better outcome in patients with radiation-induced brain necrosis.

The nature and principles of the radiation-induced cancerogenesis

International Nuclear Information System (INIS)

Lips'ka, A.YI.; Serkyiz, Ya.Yi.

2004-01-01

The paper represents the analysis of the authors and literary data concerning the nature and principles of the radiation-induced neoplasms. The mechanisms of the radiation-induced cancerogenesis development are not clear understood. The experimental data altogether do not allow developing the mathematical model of the radiation-induced cancerogenesis at the molecular level. This model has to take into account all necessary indices including radiation factor and the state of the organism. The general principles of the radiation-induced cancerogenesis have been formulated in the present review. It is possible to use these principles in order to predict and calculate the risks of the radiation-induced neoplasms

Radical production in the radiolysis of benzene

International Nuclear Information System (INIS)

LaVerne, J.A.; Araos, M.S.

1998-01-01

Complete text of publication follows. Benzene is the prototypical aromatic compound and yet the radiation chemistry of the radicals formed in its radiolysis is not well understood. Temporal information on the yield of phenyl radical, the major radical produced in the radiolysis, is important for understanding the radiation chemistry of many other types of aromatic compounds including some polymers. The effects of track structure on the production of phenyl radicals have been examined using iodine-scavenging techniques. The variation of the yields of iodobenzene and the other major molecular products such as biphenyl as a function of iodine concentration gives a good indication of the competition kinetics occurring in particle tracks. Experimental results of the scavenger experiments will be shown and their implications in the radiolysis of condensed hydrocarbons will be discussed

Reactions of Hydroxyalkyl Radicals with Cysteinyl Peptides in a NanoESI Plume

Science.gov (United States)

Stinson, Craig A.; Xia, Yu

2014-07-01

In biological systems, carbon-centered small molecule radicals are primarily formed via external radiation or internal radical reactions. These radical species can react with a variety of biomolecules, most notably nucleic acids, the consequence of which has possible links to gene mutation and cancer. Sulfur-containing peptides and proteins are reactive toward a variety of radical species and many of them behave as radical scavengers. In this study, the reactions between alkyl alcohol carbon-centered radicals (e.g., •CH2OH for methanol) and cysteinyl peptides within a nanoelectrospray ionization (nanoESI) plume were explored. The reaction system involved ultraviolet (UV) irradiation of a nanoESI plume using a low pressure mercury lamp consisting of 185 and 254 nm emission bands. The alkyl alcohol was added as solvent into the nanoESI solution and served as the precursor of hydroxyalkyl radicals upon UV irradiation. The hydroxyalkyl radicals subsequently reacted with cysteinyl peptides either containing a disulfide linkage or free thiol, which led to the formation of peptide- S-hydroxyalkyl product. This radical reaction coupled with subsequent MS/MS was shown to have analytical potential by cleaving intrachain disulfide linked peptides prior to CID to enhance sequence information. Tandem mass spectrometry via collision-induced dissociation (CID), stable isotope labeling, and accurate mass measurement were employed to verify the identities of the reaction products.

Damage induced by hydroxyl radicals generated in the hydration layer of γ-irradiated frozen aqueous solution of DNA

International Nuclear Information System (INIS)

Ohshima, Hideki; Matsuda, Akira; Kuwabara, Mikinori; Iida, Yoshiharu.

1996-01-01

Aqueous DNA solutions with or without the spin trap α-phenyl-N-tert-butylnitrone (PBN) were exposed to γ-rays at 77 K. After thawing the solutions, three experiments were carried out to confirm the generation of OH radicals in the hydration layer of DNA and to examine whether they act as an inducer of DNA strand breaks and base alterations. Observation with the EZR-spin tapping method showed ESR signals from PBN-OH adducts in the solution containing PBN and DNA, but there were few signals in the solution containing PBN alone, suggesting that reactive OH radicals were produced in the hydration layer of γ-irradiated DNA and were effectively scavenged by PBN, and that unreactive OH radicals were produced in the free water layer of γ-irradiated DNA. Agarose gel electrophoresis of DNA proved that PBN had no effect on the formation of strand breaks, whereas examination with the high-performance liquid chromatography-eloctrochemical detection (HPLC-ECD) method showed that PBN suppressed the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG). From these results it was concluded that OH radicals generated in the hydration layer of γ-irradiated DNA did not induce DNA strand breaks but induced base alterations. (author)

Radiation Protection Using Carbon Nanotube Derivatives

Science.gov (United States)

Conyers, Jodie L., Jr.; Moore, Valerie C.; Casscells, S. Ward

2010-01-01

BHA and BHT are well-known food preservatives that are excellent radical scavengers. These compounds, attached to single-walled carbon nanotubes (SWNTs), could serve as excellent radical traps. The amino-BHT groups can be associated with SWNTs that have carbolyxic acid groups via acid-base association or via covalent association. The material can be used as a means of radiation protection or cellular stress mitigation via a sequence of quenching radical species using nano-engineered scaffolds of SWNTs and their derivatives. It works by reducing the number of free radicals within or nearby a cell, tissue, organ, or living organism. This reduces the risk of damage to DNA and other cellular components that can lead to chronic and/or acute pathologies, including (but not limited to) cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. These derivatives can show an unusually high scavenging ability, which could prove efficacious in protecting living systems from radical-induced decay. This technique could be used to protect healthy cells in a living biological system from the effects of radiation therapy. It could also be used as a prophylactic or antidote for radiation exposure due to accidental, terrorist, or wartime use of radiation- containing weapons; high-altitude or space travel (where radiation exposure is generally higher than desired); or in any scenario where exposure to radiation is expected or anticipated. This invention s ultimate use will be dependent on the utility in an overall biological system where many levels of toxicity have to be evaluated. This can only be assessed at a later stage. In vitro toxicity will first be assessed, followed by in vivo non-mammalian screening in zebra fish for toxicity and therapeutic efficacy.

Radical intermediates involved in the bleaching of the carotenoid crocin. Hydroxyl radicals, superoxide anions and hydrated electrons

International Nuclear Information System (INIS)

Bors, W.; Saran, M.; Michel, C.

1982-01-01

The participation of the primary radicals in the bleaching of aqueous solutions of the carotenoid crocin by ionizing radiation was investigated, employing both X-radiolysis and pulse radiolysis. The pulse-radiolytic data demonstrated a very rapid diffusion-controlled attack by both hydroxyl radicals (radicalsOH) and hydrated electrons (e - sub(aq)), while superoxide anions (O 2 - ) did not react at all. The site of the initial reaction of these radicals was not limited to the polyene chromophore. Slower secondary reactions involving crocin alkyl or peroxy radicals contribute mainly to the overall bleaching, in particular during steady-state irradiation. (author)

Functional properties of nisin-carbohydrate conjugates formed by radiation induced Maillard reaction

Science.gov (United States)

Muppalla, Shobita R.; Sonavale, Rahul; Chawla, Surinder P.; Sharma, Arun

2012-12-01

Nisin-carbohydrate conjugates were prepared by irradiating nisin either with glucose or dextran. Increase in browning and formation of intermediate products was observed with a concomitant decrease in free amino and reducing sugar groups indicating occurrence of the Maillard reaction catalyzed by irradiation. Nisin-carbohydrate conjugates showed a broad spectrum antibacterial activity against Gram negative bacteria (Escherichia coli, Pseudomonas fluorescence) as well as Gram positive bacteria (Staphylococcus aureus, Bacillus cereus). Results of antioxidant assays, including that of DPPH radical-scavenging activity and reducing power, showed that the nisin-dextran conjugates possessed better antioxidant potential than nisin-glucose conjugate. These results suggested that it was possible to enhance the functional properties of nisin by preparing radiation induced conjugates suitable for application in food industry.

From UV Protection to Protection in the Whole Spectral Range of the Solar Radiation: New Aspects of Sunscreen Development.

Science.gov (United States)

Zastrow, Leonhard; Meinke, Martina C; Albrecht, Stephanie; Patzelt, Alexa; Lademann, Juergen

2017-01-01

Sunscreens have been constantly improving in the past few years. Today, they provide an efficient protection not only in the UVB but also in the UVA spectral region of the solar radiation. Recently it could be demonstrated that 50% of all free radicals induced in the skin due to solar radiation are formed in the visible and infrared spectral region. The good protective efficacy of sunscreens in the UV region prompts people to stay much longer in the sun than if they had left their skin unprotected. However, as no protection in the visible and infrared spectral region is provided, high amounts of free radicals are induced here that could easily exceed the critical radical concentration. This chapter describes how the effect of sunscreens can be extended to cover also the visible and infrared spectral region of the solar radiation by adding pigments and antioxidants with high radical protection factors to the sunscreen formulations.

Genetic alterations during radiation-induced carcinogenesis

International Nuclear Information System (INIS)

Kodama, Seiji

1995-01-01

This paper reviews radiation-induced genetic alterations and its carcinogenesis, focusing on the previous in vitro assay outcome. A colony formation assay using Syrian hamster fetal cells and focus formation assay using mouse C3H10T1/2 cells are currently available to find malignant transformation of cells. Such in vitro assays has proposed the hypothesis that radiation-induced carcinogenesis arises from at least two-stage processes; i.e., that an early step induced by irradiation plays an important role in promoting the potential to cause the subsequent mutation. A type of genetic instability induced by radiation results in a persistently elevated frequency of spontaneous mutations, so-called the phenomenon of delayed reproductive death. One possible mechanism by which genetic instability arises has been shown to be due to the development of abnormality in the gene group involved in the maintenance mechanism of genome stability. Another possibility has also been shown to stem from the loss of telomere (the extremities of a chromosome). The importance of search for radiation-induced genetic instability is emphasized in view of the elucidation of carcinogenesis. (N.K.)

Radiation-induced heart disease

Energy Technology Data Exchange (ETDEWEB)

Stroobandt, R; Knieriem, H J; De Wolf, L; Joossens, J V

1975-01-01

A 45-year old woman underwent a radical mastectomy in 1965 for carcinoma of the left breast with metastasis in the left axillar lymph nodes. Fifty per cent of the heart received 4,000 rads during postoperative X-ray therapy. Patient developed radiopneumonia and symptoms of acute pericarditis in 1967. Constrictive pericarditis developed gradually from 1972 on. A pericardiectomy was performed in June 1974 and a thickened pericardium could be removed. Light and electron microscopic examination of a surgical biopsy of the left ventricular epi-myocardium revealed epicardial fibrosis, interstitial fibrosis of the myocardium and perivascular fibrosis. The diagnosis of post-radiation pericarditis was made. The myocardial involvement may be responsible for the subsequent clinical course.

Radiation effects on polyethylenes

International Nuclear Information System (INIS)

Suzuki, T.; Oki, Y.; Numajiri, M.; Miura, T.; Kondo, K.; Tanabe, Y.; Ishiyama, M.; Ito, Y.

1992-01-01

Radiation effects on four kinds of polyethylenes were studied from the viewpoints of mechanical properties, free radicals and free volumes. The samples were irradiated using a cobalt 60 gamma source to give doses up to 3MGy. The degradation of mechanical strength due to gamma-irradiation was evaluated by the elongation at break and its tensile strength. Radiation induced free radicals were measured by ESR. Free volumes observed by the o-Ps component of the positron annihilation spectrum are normally the large ones located in the amorphous regions and after irradiation these are created in crystalline regions, too. The sizes and the relative numbers of free volumes were evaluated by lifetimes and intensities of a long-lived component of positronium, respectively. Using these data, the properties of polyethylenes before and after irradiation are discussed. (author)

Development of radiation-inducible promoters for use in nitric oxide synthase gene therapy of cancer

International Nuclear Information System (INIS)

Hirst, D.G.; Worthington, J.; Adams, C.; Robson, T.; Scott, S.D.

2003-01-01

Full text: The free radical nitric oxide (NO) at nM concentrations performs multiple signaling roles that are essential for survival. These processes are regulated via the enzymes nNOS and eNOS, but another isoform, inducible nitric oxide synthase (iNOS) is capable of generating much higher concentrations (mM) over longer periods, resulting in the generation of very toxic species such as peroxynitrite. At high concentrations NO has many of the characteristics of an ideal anticancer molecule: it is cytotoxic (pro-apoptotic via peroxynitrite), it is a potent chemical radiosensitizer, it is anti-angiogenic and anti-metastatic. Thus, we see iNOS gene therapy as a strategy for targeting the generation of high concentrations of NO to tumours for therapeutic benefit. iNOS gene therapy should be used in combination with radiotherapy; so it is logical that the use of a radiation-inducible promoter should be part of the targeting strategy. We have tested several candidate promoters in vitro and in vivo. The WAF1 promoter has many of the properties desirable for therapeutic use including: rapid 3-4 fold induction at X-ray doses of 2 and 4Gy and no significant leakiness. WAF1 also has the advantage of being inducible by hypoxia and by the final product, NO. We have also tested the synthetic CArG promoter and demonstrated that, in addition to a high level of radiation inducibility, it is also inducible by NO. We have also been able to demonstrate potent radiosensitization (SER 2.0-2.5) in tumour cells in vitro and in vivo using iNOS gene transfer with constitutive or radiation-inducible promoters. We have also tested the use of iNOS gene therapy in combination with cisplatin and shown significant enhancement

Induction of radiation resistance and radio-protective mechanism. On the reactive oxygen and free radical

International Nuclear Information System (INIS)

Yukawa, Osami

2003-01-01

Radical scavenging system for reactive oxygen species (ROS) leading to radio-protection is reviewed on findings in animals, tissues and cells. Protection against oxygen toxicity in evolution can be seen in anaerobes' superoxide dismutase (SOD) over 3500 million years ago. ROS is generated endogenously and also by radiation. However, the intracellular sites of the generated ROS are different depending on its cause. The protection is done through enzymes like SOD, peroxidase, catalase, glutathione-related enzymes and through substances like GSH, α-tocopherol, ascorbic acid etc. Induction of ROS scavenging substances related with radio-resistance includes the responses to the low dose radiation (5-50 cGy) in those enzymes described above; to middle to high dose radiation (1-30 Gy) in a similar and in other unknown mechanisms; to exposure of ROS like H 2 O 2 at low concentration; and to antioxidant treatment. The cross-resistance between radiation and drugs suggests necessity of this induction. (N.I.)

Radiation-electrochemistry of the colloidal gold micro-electrode: Hydrogen formation by organic free radicals

International Nuclear Information System (INIS)

Westerhausen, J.; Henglein, A.; Lilie, J.

1981-01-01

Various organic free radicals as well as Ni + ions produce hydrogen in the presence of some 10 -4 M of colloidal gold. The gold catalyst was prepared via the reduction of HAuCl 4 either thermally by citrate or by γ-irradiation. The organic radicals were radiolytically produced. The mechanism of H 2 formation includes electron transfer from the organic radicals to the gold particles, storage of a large number of electrons per gold particle, conversion of the electrons into adsorbed H-atoms and desorption of the latter to form H 2 . - The rates of some of these steps were measured using the method of pulse radiolysis. 1-Hydroxy-1-methyl ethyl radicals, (CH 3 ) 2 COH, react with colloidal gold particles almost diffusion controlled provided that the gold particles are not charged with excess electrons. Charged gold particles react at a substantially lower rate. The stored electrons live seconds or even minutes depending on their number per gold particle. In the stationary state, up to 0.38 Coulomb of electrons could be stored per liter of a 2.9x10 -4 molar gold solution, each gold particle carrying about 39 electrons. A comparison is also made between the catalytic activities of colloidal gold and silver. Due to the relative fast conversion of electrons into adsorbed H-atoms, colloidal gold has less capacity for the storage of electrons than colloidal silver. - The dependence of the hydrogen yield on the pH of the solution, the concentration of gold, the size of the gold particles, the concentration of the polyvinyl alcohol stabilizer, and the intensity of radiation was also investigated. At high intensities, some of the radicals are destroyed in a gold catalysed disproportionation. (orig.)

The inflammatory response plays a major role in the acute radiation syndrome induced by fission radiation

International Nuclear Information System (INIS)

Agay, D.; Chancerelle, Y.; Hirodin, F.; Mathieu, J.; Multon, E.; Van Uye, A.; Mestries, J.C.

1997-01-01

At high dose rates, both gamma and neutron irradiation induce an acute inflammatory syndrome with huge intercellular communication disorders. This inflammatory syndrome evolves in two phases, separated by a latency phase. During the prodromal phase, the molecular and cellular lesions induced by free radicals trigger an initial response which associates cellular repair and multicellular interactions involving both humoral and nervous communications. A large part of perturbations constitute a non specific inflammatory syndrome and clinically silent coagulation disorders which are linked by common intercellular mediators. All these perturbations are rapidly reversible and there is no correlation between the radiation dose and the severity of the response. During the manifest-illness phase, both inflammatory and coagulation disorders resume, slightly preceding the clinical symptoms. Biochemical symptoms are moderate in the animals which will survive, but they escape regulatory mechanisms in those which will die, giving rise to a vicious circle. These biochemical disorders are largely responsible for the death. With lower dose rates, it cannot be excluded that great cellular communication disorders take place at the tissue level, with limited blood modifications. This aspect should be taken into account for the optimization of cytokine therapies. (authors)

Biological effects of ionizing radiation

International Nuclear Information System (INIS)

Gisone, Pablo; Perez, Maria R.

2001-01-01

It has been emphasised the importance of DNA as the main target for ionizing radiation, that can induce damage by its direct action on this molecule or by an indirect effect mediated by free-radicals generated by water radiolysis. Biological effects of ionizing radiation are influenced not only by the dose but also by the dose-rate and the radiation quality. Radiation induced damage, mainly DNA single and double strand breaks, is detected by molecular sensors which in turn trigger signalling cascades leading to cell cycle arrest to allow DNA repair or programmed cell death (apoptosis). Those effects related with cell death, named deterministic, exhibits a dose-threshold below which they are not observed. Acute radiation syndrome and radiological burns are examples of this kind of effects. Other radiation induced effects, called stochastic, are the consequence of cell transformation and do not exhibit a dose-threshold. This is the case of cancer induction and hereditary effects. The aim of this presentation is briefly describe the main aspects of deterministic and stochastic effects from the point of view of radiobiology and radio pathology. (author)

Nardostachys Jatamansi root extract protects of radiation induced glycogen depletion in Albino Wistar rats

International Nuclear Information System (INIS)

Damodara Gowda, K.M.; Krishna, A.P.; Shetty, Lathika; Suchetha Shetty, N.; Sanjeev, Ganesh

2013-01-01

Exposure to ionizing radiation cause variety of pathological processes in irradiated cells. The killing action of ionizing radiation is mainly mediated through the free radicals generated from the radiolysis of cellular water. In the present study, protective effects of Nardostachys Jatamansi root extract (NJE) on radiation induced depletion of glycogen in rats exposed to 3 Gy whole body electron beam irradiation (EBR) was investigated. EBR was performed at Microtron centre, Mangalore University. Treatment of rats with NJE at a dosage of 100, 200 and 400 mg/kg bw respectively once daily for 15 days before, after and both before and after irradiation was done. The liver, kidney and muscle was separated and used for the estimation of total glycogen content using standard procedures and also for the histochemical localization of glycogen by PAS staining method. The data was analyzed by paired t test and Kruskal Wallis test. P<0.05 was the level of significance. The irradiated rats exhibited significant decline (p=0.000) in the level of total glycogen content in the tissues of liver, kidney and muscle whereas, a nonsignificant variation was recorded in rats treated with NJE. This study indicated that treatment with NJE both before and after irradiation for 15 consecutive days provided significant protection against irradiation induced depletion of glycogen. (author)

Amelioration of radiation induced oxidative stress using water soluble chitosan produced by Aspergillus niger

International Nuclear Information System (INIS)

EL-Sonbaty, S.M.; Swailam, H.M.; Noaman, E.

2012-01-01

Chitosan is a natural polysaccharide synthesized by a great number of living organisms and considered as a source of potential bioactive material and has many biological applications which are greatly affected by its solubility in neutral ph. In this study low molecular weight water soluble chitosan was prepared by chemical degradation of chitosan produced by Aspergillus niger using H 2 O 2 . Chitosan chemical structure was detected before and after treatment using FTIR spectrum, and its molecular weight was determined by its viscosity using viscometer. Its antioxidant activity against gamma radiation was evaluated in vivo using rats. Rats were divided into 4 groups; group 1: control, group 2: exposed to acute dose of gamma radiation (6 Gy), group 3: received water soluble chitosan, group 4: received water soluble chitosan then exposed to gamma radiation as group 2. Gamma radiation significantly increased malonaldehyde, decreased glutathione concentration, activity of superoxide dismutase, catalase, and glutatione peroxidase, while significantly increase the activity of alanine transferase, aspartate transferase, urea and creatinine concentration. Administration of water soluble chitosan has ameliorated induced changes caused by gamma radiation. It could be concluded that water soluble chitosan by scavenging free radicals directly or indirectly may act as a potent radioprotector against ionizing irradiation.

Radiation-induced brain injury: A review

Energy Technology Data Exchange (ETDEWEB)

Greene-Schloesser, Dana; Robbins, Mike E.; Peiffer, Ann M.; Shaw, Edward G. [Department of Radiation Oncology, Wake Forest School of Medicine,, Winston-Salem, NC (United States); Brain Tumor Center of Excellence, Wake Forest School of Medicine,, Winston-Salem, NC (United States); Wheeler, Kenneth T. [Brain Tumor Center of Excellence, Wake Forest School of Medicine,, Winston-Salem, NC (United States); Department of Radiology, Wake Forest School of Medicine,, Winston-Salem, NC (United States); Chan, Michael D., E-mail: mrobbins@wakehealth.edu [Department of Radiation Oncology, Wake Forest School of Medicine,, Winston-Salem, NC (United States); Brain Tumor Center of Excellence, Wake Forest School of Medicine,, Winston-Salem, NC (United States)

2012-07-19

Approximately 100,000 primary and metastatic brain tumor patients/year in the US survive long enough (>6 months) to experience radiation-induced brain injury. Prior to 1970, the human brain was thought to be highly radioresistant; the acute CNS syndrome occurs after single doses >30 Gy; white matter necrosis occurs at fractionated doses >60 Gy. Although white matter necrosis is uncommon with modern techniques, functional deficits, including progressive impairments in memory, attention, and executive function have become important, because they have profound effects on quality of life. Preclinical studies have provided valuable insights into the pathogenesis of radiation-induced cognitive impairment. Given its central role in memory and neurogenesis, the majority of these studies have focused on the hippocampus. Irradiating pediatric and young adult rodent brains leads to several hippocampal changes including neuroinflammation and a marked reduction in neurogenesis. These data have been interpreted to suggest that shielding the hippocampus will prevent clinical radiation-induced cognitive impairment. However, this interpretation may be overly simplistic. Studies using older rodents, that more closely match the adult human brain tumor population, indicate that, unlike pediatric and young adult rats, older rats fail to show a radiation-induced decrease in neurogenesis or a loss of mature neurons. Nevertheless, older rats still exhibit cognitive impairment. This occurs in the absence of demyelination and/or white matter necrosis similar to what is observed clinically, suggesting that more subtle molecular, cellular and/or microanatomic modifications are involved in this radiation-induced brain injury. Given that radiation-induced cognitive impairment likely reflects damage to both hippocampal- and non-hippocampal-dependent domains, there is a critical need to investigate the microanatomic and functional effects of radiation in various brain regions as well as their

Radiation-induced brain injury: A review

International Nuclear Information System (INIS)

Greene-Schloesser, Dana; Robbins, Mike E.; Peiffer, Ann M.; Shaw, Edward G.; Wheeler, Kenneth T.; Chan, Michael D.

2012-01-01

Approximately 100,000 primary and metastatic brain tumor patients/year in the US survive long enough (>6 months) to experience radiation-induced brain injury. Prior to 1970, the human brain was thought to be highly radioresistant; the acute CNS syndrome occurs after single doses >30 Gy; white matter necrosis occurs at fractionated doses >60 Gy. Although white matter necrosis is uncommon with modern techniques, functional deficits, including progressive impairments in memory, attention, and executive function have become important, because they have profound effects on quality of life. Preclinical studies have provided valuable insights into the pathogenesis of radiation-induced cognitive impairment. Given its central role in memory and neurogenesis, the majority of these studies have focused on the hippocampus. Irradiating pediatric and young adult rodent brains leads to several hippocampal changes including neuroinflammation and a marked reduction in neurogenesis. These data have been interpreted to suggest that shielding the hippocampus will prevent clinical radiation-induced cognitive impairment. However, this interpretation may be overly simplistic. Studies using older rodents, that more closely match the adult human brain tumor population, indicate that, unlike pediatric and young adult rats, older rats fail to show a radiation-induced decrease in neurogenesis or a loss of mature neurons. Nevertheless, older rats still exhibit cognitive impairment. This occurs in the absence of demyelination and/or white matter necrosis similar to what is observed clinically, suggesting that more subtle molecular, cellular and/or microanatomic modifications are involved in this radiation-induced brain injury. Given that radiation-induced cognitive impairment likely reflects damage to both hippocampal- and non-hippocampal-dependent domains, there is a critical need to investigate the microanatomic and functional effects of radiation in various brain regions as well as their

Delayed Radiation-Induced Vasculitic Leukoencephalopathy

Energy Technology Data Exchange (ETDEWEB)

Rauch, Philipp J. [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States); Faculty of Medicine, University of Heidelberg, Heidelberg (Germany); Park, Henry S. [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States); Knisely, Jonathan P.S. [Department of Radiation Medicine, North Shore University Hospital, Manhasset, New York (United States); Chiang, Veronica L. [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States); Vortmeyer, Alexander O., E-mail: alexander.vortmeyer@yale.edu [Departments of Pathology and Neurosurgery, Yale University School of Medicine, New Haven, Connecticut (United States)

2012-05-01

Purpose: Recently, single-fraction, high-dosed focused radiation therapy such as that administered by Gamma Knife radiosurgery has been used increasingly for the treatment of metastatic brain cancer. Radiation therapy to the brain can cause delayed leukoencephalopathy, which carries its own significant morbidity and mortality. While radiosurgery-induced leukoencephalopathy is known to be clinically different from that following fractionated radiation, pathological differences are not well characterized. In this study, we aimed to integrate novel radiographic and histopathologic observations to gain a conceptual understanding of radiosurgery-induced leukoencephalopathy. Methods and Materials: We examined resected tissues of 10 patients treated at Yale New Haven Hospital between January 1, 2009, and June 30, 2010, for brain metastases that had been previously treated with Gamma Knife radiosurgery, who subsequently required surgical management of a symptomatic regrowing lesion. None of the patients showed pathological evidence of tumor recurrence. Clinical and magnetic resonance imaging data for each of the 10 patients were then studied retrospectively. Results: We provide evidence to show that radiosurgery-induced leukoencephalopathy may present as an advancing process that extends beyond the original high-dose radiation field. Neuropathologic examination of the resected tissue revealed traditionally known leukoencephalopathic changes including demyelination, coagulation necrosis, and vascular sclerosis. Unexpectedly, small and medium-sized vessels revealed transmural T-cell infiltration indicative of active vasculitis. Conclusions: We propose that the presence of a vasculitic component in association with radiation-induced leukoencephalopathy may facilitate the progressive nature of the condition. It may also explain the resemblance of delayed leukoencephalopathy with recurring tumor on virtually all imaging modalities used for posttreatment follow-up.

Computer modelling of radiation-induced bystander effect

International Nuclear Information System (INIS)

Khvostunov, Igor K.; Nikjoo, Hooshang

2002-01-01

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

Radiation-induced transformations of cellulose ethers

International Nuclear Information System (INIS)

Nud'ga, L.A.; Petropavlovskii, G.S.; Plisko, E.A.; Isakova, O.V.; Ershov, B.G.

1988-01-01

The purpose of this investigation was to study the transformation which take place under the action of γ-radiation in a number of cellulose ethers containing both saturated (carboxymethyl, hydroxyethyl) and unsaturated (allyl, methacryloyl) groups. Irradiation was carried out on a 60 Co unit in air at 77 and 300 K; the dose rate was 37 and 50 kGy/h respectively. The EPR spectra of γ-irradiated hydroxyethyl- and allylhydroxyethylcelluloses are identical. Under the action of γ-radiation extensive changes took place in cellulose ethers which are exhibited in degradation or the formation of three-dimensional structures and are accompanied by a change in the functional composition. The efficiency in the formation of radicals and their localization are determined by the nature and number of substituents in the cellulose ethers

Radiation-induced chromosomal instability

International Nuclear Information System (INIS)

Ritter, S.

1999-01-01

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

Ascorbic acid reduced mutagenicity at the HPRT locus in CHO cells against thermal neutron radiation

International Nuclear Information System (INIS)

Kinashi, Yuko; Sakurai, Yoshinori; Masunaga, Shinichiro; Suzuki, Minoru; Nagata, Kenji; Ono, Koji

2004-01-01

We investigated the biological effects of the long-lived radicals induced following neutron irradiation. It has been reported that radiation-induced long-lived radicals were scavenged by post-irradiation treatment of ascorbic acid (Koyama, 1998). We studied the effects of ascorbic acid acting as a long-lived radical scavenger on cell killing and mutagenicity in Chinese hamster ovary cells against thermal neutrons produced at the Kyoto University Research reactor. Ascorbic acid was added to cells 30 min after neutron irradiation and removed 150 min after irradiation. The biological end point of cell survival was measured by colony formation assay. The mutagenicity was measured by the mutant frequency in the HPRT locus. The post-irradiation treatment of ascorbic acid did not alter the cell killing effect of neutron radiation. However, the mutagenicity was decreased, especially when the cells were irradiated with boron. Our results suggested that ascorbic acid scavenged long-lived radicals effectively and caused apparent protective effects against mutagenicity of boron neutron capture therapy

Role of neurotensin in radiation-induced hypothermia in rats

International Nuclear Information System (INIS)

Kandasamy, S.B.; Hunt, W.A.; Harris, A.H.

1991-01-01

The role of neurotensin in radiation-induced hypothermia was examined. Intracerebroventricular (ICV) administration of neurotensin produced dose-dependent hypothermia. Histamine appears to mediate neurotensin-induced hypothermia because the mast cell stabilizer disodium cromoglycate and antihistamines blocked the hypothermic effects of neurotensin. An ICV pretreatment with neurotensin antibody attenuated neurotensin-induced hypothermia, but did not attenuate radiation-induced hypothermia, suggesting that radiation-induced hypothermia was not mediated by neurotensin

Differential radioprotection and free radical scavenging activity of Caesalpinia digyna extracts and the active constituent

International Nuclear Information System (INIS)

Singh, Umang; Kunwar, A.; Barik, A.; Priyadarsini, K.I.; Mula, S.; Srinivasan, R.

2008-01-01

Differential free radical activity of the fractionated extracts (F1: methanolic fraction, F2: acetone soluble fraction and F3: acetone insoluble fraction) of a medicinal plant Caesalpinia digyna, has been studied employing DPPH, superoxide radical and in vitro radioprotecting activity by following their effect on radiation induced protein carbonylation and DNA damage in pBR322. The activity for these fractions is in the order of F1>F2>F3. HPLC analysis indicated that all fractions contain high amount of bergenin, a polyhydroxy isocoumarin derivative and the fractions are more active than isolated bergenin. (author)

Differential radioprotection and free radical scavenging activity of Caesalpinia digyna extracts and the active constituent

Energy Technology Data Exchange (ETDEWEB)

Singh, Umang; Kunwar, A; Barik, A; Priyadarsini, K I [Radiation and Photochemistry Div., Bhabha Atomic Research Centre, Mumbai (India); Mula, S [Bio-Organic Div., Bhabha Atomic Research Centre, Mumbai (India); Srinivasan, R [JSS College of Pharmacy, Ootacamund (India)

2008-01-15

Differential free radical activity of the fractionated extracts (F1: methanolic fraction, F2: acetone soluble fraction and F3: acetone insoluble fraction) of a medicinal plant Caesalpinia digyna, has been studied employing DPPH, superoxide radical and in vitro radioprotecting activity by following their effect on radiation induced protein carbonylation and DNA damage in pBR322. The activity for these fractions is in the order of F1>F2>F3. HPLC analysis indicated that all fractions contain high amount of bergenin, a polyhydroxy isocoumarin derivative and the fractions are more active than isolated bergenin. (author)

Free radical scavenger edaravone suppresses X-ray-induced apoptosis through p53 inhibition in MOLT-4 cells

International Nuclear Information System (INIS)

Sasano, Nakashi; Shiraishi, Kenshiro; Igaki, Hiroshi; Nakagawa, Keiichi; Enomoto, Atsushi; Hosoi, Yoshio; Matsumoto, Yoshihisa; Miyagawa, Kiyoshi; Katsumura, Yosuke

2007-01-01

Edaravone, a clinical drug used widely for the treatment of acute cerebral infarction, is reported to scavenge free radicals. In the present study, we investigated the radioprotective effect of edaravone on X-ray-induced apoptosis in MOLT-4 cells. Apoptosis was determined by the dye exclusion test, Annexin V binding assay, cleavage of caspase, and DNA fragmentation. We found that edaravone significantly suppressed the X-ray-induced apoptosis. The amount of intracellular reactive oxygen species (ROS) production was determined by the chloromethyl-2', 7'-dichlorodihydro-fluorescein diacetate system. We found that the intracellular ROS production by X-irradiation was completely suppressed by the addition of edaravone. The accumulation and phosphorylation of p53 and the expression of p21 WAF1 , a target protein of p53, which were induced by X-irradiation, were also suppressed by adding edaravone. We conclude that the free radical scavenger edaravone suppresses X-ray-induced apoptosis in MOLT-4 cells by inhibiting p53. (author)

Free radical scavenger edaravone suppresses X-ray-induced apoptosis through p53 inhibition in MOLT-4 cells

Energy Technology Data Exchange (ETDEWEB)

Sasano, Nakashi; Shiraishi, Kenshiro; Igaki, Hiroshi; Nakagawa, Keiichi [Tokyo Univ., Graduate School of Medicine, Tokyo (Japan); Enomoto, Atsushi; Hosoi, Yoshio; Matsumoto, Yoshihisa; Miyagawa, Kiyoshi [Tokyo Univ., Faculty of Medicine, Tokyo (Japan); Katsumura, Yosuke [Tokyo Univ., Graduate School of Engineering, Tokyo (Japan)

2007-11-15

Edaravone, a clinical drug used widely for the treatment of acute cerebral infarction, is reported to scavenge free radicals. In the present study, we investigated the radioprotective effect of edaravone on X-ray-induced apoptosis in MOLT-4 cells. Apoptosis was determined by the dye exclusion test, Annexin V binding assay, cleavage of caspase, and DNA fragmentation. We found that edaravone significantly suppressed the X-ray-induced apoptosis. The amount of intracellular reactive oxygen species (ROS) production was determined by the chloromethyl-2', 7'-dichlorodihydro-fluorescein diacetate system. We found that the intracellular ROS production by X-irradiation was completely suppressed by the addition of edaravone. The accumulation and phosphorylation of p53 and the expression of p21{sup WAF1}, a target protein of p53, which were induced by X-irradiation, were also suppressed by adding edaravone. We conclude that the free radical scavenger edaravone suppresses X-ray-induced apoptosis in MOLT-4 cells by inhibiting p53. (author)

Relationship between radiation induced activation of DNA repair genes and radiation induced apoptosis in human cell line A431

International Nuclear Information System (INIS)

Bom, Hee Seung; Min, Jung Jun; Kim, Kyung Keun; Choi, Keun Hee

2000-01-01

The purpose of this study was to evaluate the relationship between radiation-induced acivation of DNA repair genes and radiation induced apoptosis in A431 cell line. Five and 25 Gys of gamma radiation were given to A431 cells by a Cs-137 cell irradiator. Apoptosis was evaluated by flow cytometry using annexin V-fluorescein isothiocyanate and propidium iodide staining. The expression of DNA repair genes was evaluated by both Northern and Western blot analyses. The number of apoptotic cells increased with the increased radiation dose. It increased most significantly at 12 hours after irradiation. Expression of p53, p21, and ℎRAD50 reached the highest level at 12 hours after 5 Gy irradiation. In response to 25 Gy irradiation, ℎRAD50 and p21 were expressed maximally at 12 hours, but p53 and GADD45 genes showed the highest expression level after 12 hours. Induction of apoptosis and DNA repair by ionizing radiation were closely correlated. The peak time of inducing apoptosis and DNA repair was 12 hours in this study model. ℎRAD50, a recently discovered DNA repair gene, was also associated with radiation-induced apoptosis.=20

Study on radiation-inducible genes

Energy Technology Data Exchange (ETDEWEB)

Lim, Sang Yong; Kim, Dong Ho; Joe, Min Ho; Song, Hyu Npa

2012-01-15

Transcription of previously identified radiation-inducible genes, uscA and cyoA, was examined responding to radiation. The putative promoter regions of both genes were cloned into pRS415 vector containing lacZ, and the core promoter region necessary for radiation response were determined through promoter deletion method. To investigate the role of uscA, which is assumed to be small RNA related with radiation response, a deletion mutant strain of uscA was constructed. However, uscA deletion did not affect bacterial survival against radiation exposure. The use of bacteria as anticancer agents has attracted interest. In this study, we tried to develop tumor targeting bacteria in which the radiation-inducible promoter activate a transgene encoding a cytotoxic protein. For outward secretion of anticancer protein produced inside bacteria, the N-terminal 140 amino acid of SspH1 was found to function as a secretion signal peptide. To create an attenuated tumor-targeting bacteria, Salmonella ptsI mutant strain was constructed, and we found that its virulence decreased. Finally, the tumor-targeting ability of ptsI mutant was verified by the use of in-vivo imaging analysis.

Study on radiation-inducible genes

International Nuclear Information System (INIS)

Lim, Sang Yong; Kim, Dong Ho; Joe, Min Ho; Song, Hyu Npa

2012-01-01

Transcription of previously identified radiation-inducible genes, uscA and cyoA, was examined responding to radiation. The putative promoter regions of both genes were cloned into pRS415 vector containing lacZ, and the core promoter region necessary for radiation response were determined through promoter deletion method. To investigate the role of uscA, which is assumed to be small RNA related with radiation response, a deletion mutant strain of uscA was constructed. However, uscA deletion did not affect bacterial survival against radiation exposure. The use of bacteria as anticancer agents has attracted interest. In this study, we tried to develop tumor targeting bacteria in which the radiation-inducible promoter activate a transgene encoding a cytotoxic protein. For outward secretion of anticancer protein produced inside bacteria, the N-terminal 140 amino acid of SspH1 was found to function as a secretion signal peptide. To create an attenuated tumor-targeting bacteria, Salmonella ptsI mutant strain was constructed, and we found that its virulence decreased. Finally, the tumor-targeting ability of ptsI mutant was verified by the use of in-vivo imaging analysis

Combination is the dominant free radical process initiated in DNA by ionizing radiation: an overview based on solid-state EPR studies

International Nuclear Information System (INIS)

Bernhard, W.A.; Mroczka, N.; Barnes, J.

1994-01-01

An overview of the early processes initiated in DNA by ionizing radiation is given from the perspective of studies done by solid-state EPR with the focus on radical combination. Comparisons with free radical formation and trapping in crystalline pyrimidines (1-methylcytosine, thymine, 1-methylthymine, 1-methyluracil, and cytosine monohydrate) provide insight into the processes occurring in DNA. Between 25 and 50% of low LET ionizations in fully hydrated DNA at 4 K lead to trapped free radicals, the remaining unobserved radicals are assumed to have combined. The majority of the radicals trapped in DNA at 4 K (G ∼ 0.3 μmol/J) are believed to be in clusters. Based on the value of G, it is argued that the range of holes and bound electrons in DNA at 4 K are, in the main, limited to within the cluster diameter, ∼ 4 nm. Proton transfer across hydrogen bonds promotes radical trapping and inhibits combination but is thermally reversible. Warming to room temperature mobilizes the reversibly trapped radicals and gives additional combination (50-80% of those trapped at 4 K). The yield of free radicals, after anneal, is sufficient to account for the yield of single-strand breaks produced by direct effects. (Author)

Role of endothelium in radiation-induced normal tissue damages

International Nuclear Information System (INIS)

Milliat, F.

2007-05-01

More than half of cancers are treated with radiation therapy alone or in combination with surgery and/or chemotherapy. The goal of radiation therapy is to deliver enough ionising radiation to destroy cancer cells without exceeding the level that the surrounding healthy cells can tolerate. Unfortunately, radiation-induced normal tissue injury is still a dose limiting factor in the treatment of cancer with radiotherapy. The knowledge of normal tissue radiobiology is needed to determine molecular mechanisms involved in normal tissue pathogenic pathways in order to identify therapeutic targets and develop strategies to prevent and /or reduce side effects of radiation therapy. The endothelium is known to play a critical role in radiation-induced injury. Our work shows that endothelial cells promote vascular smooth muscle cell proliferation, migration and fibro-genic phenotype after irradiation. Moreover, we demonstrate for the first time the importance of PAI-1 in radiation-induced normal tissue damage suggesting that PAI-1 may represent a molecular target to limit injury following radiotherapy. We describe a new role for the TGF-b/Smad pathway in the pathogenesis of radiation-induced damages. TGF-b/Smad pathway is involved in the fibro-genic phenotype of VSMC induced by irradiated EC as well as in the radiation-induced PAI-1 expression in endothelial cells. (author)

Radiation-Induced Carotid Artery Stenosis in a Patient with Carcinoma of the Oral Floor

Directory of Open Access Journals (Sweden)

Kahori Seto

2013-01-01

Full Text Available Radiation-induced carotid artery stenosis (RI-CS, a life-threatening condition, can occur after external radiation for head and neck cancer. We here describe a case of asymptomatic RI-CS in a 73-year-old patient treated with chemoradiotherapy and radical neck dissection for a basaloid squamous cell carcinoma of the oral floor. Stenosis of the left carotid artery, diagnosed as RI-CS, showed on an MRI performed 1.5 years after radiotherapy. Blood from the left side of the anterior cerebral artery and the middle anterior artery was flowing to the brain through the anterior and posterior communicating arteries, so no stent surgery or other treatment was necessary. The cancer has not recurred during approximately 5 years of followup after radiotherapy, and the patient has had no adverse effects from the RI-CS since it was diagnosed 3.5 years ago. This case emphasizes the necessity of early scrutiny for RI-CS in patients given radiotherapy for oral cancer.

Squalene Modulates Radiation-Induced Structural, Ultrastructural And Biochemical Changes In Cardiac Muscles Of Male Albino Rats

International Nuclear Information System (INIS)

REZK, R.G.; YACOUB, S.F.; ABDEL AZIZ, N.

2009-01-01

The failing heart represents an enormous clinical problem and is a major cause of death throughout the world. Hyperlipidemia and oxidative stress have been shown to contribute to heart failure. Squalene is a remarkable bioactive substance that belongs to a class of antioxidants called isoprenoids, which neutralize the harmful effect of excessive free radicals production in the body.The present study was designed to determine the possible protective effect of squalene against oxidative cardiac muscle damage induced by gamma irradiation.Rats were treated daily by gavage with 0.4 ml/kg squalene for 42 days before whole body gamma irradiation at a dose of 4 Gy and continued until animals were sacrificed 3 days post irradiation.Histological examination of cardiac muscles sections by using light and electron microscopes showed that exposure of rats to ionizing radiation has provoked a severe architecture damage such as necrotic nuclei, nuclei located at the periphery, alteration in chromatin distribution, ruptured cell and mitochondrial membranes, cristae of mitochondria disappeared, sticking mitochondria and ruptured myofibers. Structural and ultra-structural changes were associated with severe oxidative stress. Significant increase of lipid peroxidation products (malondialdehyde) (MDA) along with reduction in the activity of the antioxidant enzymes; superoxide dismutase (SOD) and catalse (CAT), and glutathione content (GSH), were recorded.Treatment of rats with squalene has significantly attenuated the radiation-induced oxidative damage and histopathological changes in cardiac muscle which was substantiated by a significant amelioration in the activity of plasma lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and aspartate transaminase (AST). Furthermore, administration of squalene to rats has adjusted the radiation-induced increase in plasma triglycerides (TG), total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C). Based on these results, it

Radiation effects on polymer materials. Ionizing radiation induces degradation or improvement? (2) Gas evolution by irradiation

International Nuclear Information System (INIS)

Sasuga, Tsuneo

2005-01-01

The present article reviews gas evolution from organic polymers induced by ionizing radiations, focusing on gamma-ray irradiation of PE (polyethylene) and PP (polypropylene)-model compounds at temperatures from -77 to 55degC. In the polyolefins, the main gas evolved by irradiation is hydrogen with G-value of 3-4 at room temperatures and G(H 2 ) is 1.8 at 77K. For PE, G(H 2 ) is higher for the low-density PE than for higher-density PE. For the halogenated polymers as PVC, etc., evolved gas is hydrogen halogenated: G(HCl)=6.8 for PVC. For the case where the irradiation is accompanied with the oxidation of polymers, the de-oxygenation and formation of carboxylic radicals are remarkably high and known to emit a bad smell which depends on the thickness of oxidized layers. In conclusion, the gas evolution can be estimated by considering the molecular structure of polymer materials. (S.Ohno)

Radiation-induced polymerization of water-saturated styrene in a wide range of dose rate

International Nuclear Information System (INIS)

Takezaki, J.; Okada, T.; Sakurada, I.

1978-01-01

Radiation-induced polymerization of water-saturated styrene (water content 3.5 x 10 -2 mole/liter) was carried out in a wide range of dose rate between 1.2 x 10 3 and 1.8 x 10 7 rad/sec, and compared with the polymerization of the moderately dried styrene (water content 3.2 x 10 -3 mole/liter). Molecular weight distribution curves of the polymerization products showed that they were generally consisted of four parts, namely, oligomers, radical, cationic, and super polymers. Contributions of the four constituents to the polymerization and the number average degrees of polymerization (DP) of the four kinds of polymers were calculated by the graphical analysis of the curves. The rate of radical polymerization and DP of radical polymers are independent of the water content; the dose rate dependences of the polymerization rate and DP agree with the well known square root and inverse square root laws, respectively, of the radical polymerization of styrene. The rate of ionic polymerization is directly proportional to the dose rate, but it decreases, at a given dose rate, inversely proportional to the water content of styrene. DP of ionic polymer is independent of the dose rate but decreases with increasing water content. The super polymer of DP about 10 4 is not formed in the case of the moderately dried styrene. G values for the initiating radical and ion formation are calculated to be independently of the dose rate and water content, 0.66 and 0.027, respectively. It was suggested that oligomer was formed in the early stage by the interaction of cation with anion and only those cations which had survived underwent polymerization. 10 figures, 4 tables

Heavy-ion radiation induced bystander effect in mice

Science.gov (United States)

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

2012-07-01

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

A study of radiation-induced cerebral vascular injury in nasopharyngeal carcinoma patients with radiation-induced temporal lobe necrosis.

Directory of Open Access Journals (Sweden)

Jianhong Ye

Full Text Available To investigate radiation-induced carotid and cerebral vascular injury and its relationship with radiation-induced temporal lobe necrosis in nasopharyngeal carcinoma (NPC patients.Fifty eight NPC patients with radiation-induced temporal lobe necrosis (TLN were recruited in the study. Duplex ultrasonography was used to scan bilateral carotid arterials to evaluate the intima-media thickness (IMT and occurrence of plaque formation. Flow velocities of bilateral middle cerebral arteries (MCAs, internal carotid arteries (ICAs and basal artery (BA were estimated through Transcranial Color Doppler (TCD. The results were compared with data from 33 patients who were free from radiation-induced temporal lobe necrosis after radiotherapy and 29 healthy individuals.Significant differences in IMT, occurrence of plaques of ICAs and flow velocities of both MCAs and ICAs were found between patients after radiotherapy and healthy individuals (p<0.05. IMT had positive correlation with post radiation interval (p = 0.049. Compared with results from patients without radiation-induced TLN, the mean IMT was significantly thicker in patients with TLN (p<0.001. Plaques were more common in patients with TLN than patients without TLN (p = 0.038. In addition, flow velocities of MCAs and ICAs in patients with TLN were much faster (p<0.001, p<0.001. Among patients with unilateral TLN, flow velocity of MCAs was significantly different between ipsilateral and contralateral sides to the lesion (p = 0.001.Thickening of IMT, occurrence of plaque formation and hemodynamic abnormality are more common in patients after radiotherapy, especially in those with TLN, compared with healthy individuals.

Radiation-induced heart injury. Radiopathological study

Energy Technology Data Exchange (ETDEWEB)

Suzuki, Y; Niibe, H [Gunma Univ., Maebashi (Japan). School of Medicine

1975-11-01

In order to identify radiation-induced heart injury and to differentiate it from heart disease, an attempt was made to clarify post-irradiation heart injury by investigating the histological changes which occur during the interval between the irradiation and the time of demonstrable histological changes. A study was made of 83 autopsies in which most of the primary neoplasms were breast cancers, lung cancers and mediastinal tumors. In 43 of these autopsies the heart had been irradiated. Sixty eight dd-strain mice were also used for microautoradiographic study. Histological changes in the heart were observed in 27 of the 43 cases receiving irradiation. The limit of the tolerance dose to the heart for indicating histological changes was 1220 ret in humans. The latent period without histological changes was 2.7 months after initiation of radiation therapy. Greater heart injury was observed after re-irradiation or after the combined therapy of radiation and chemotherapy especially mitomycin (MMC). The histological findings after treatment with MMC were similar to those of radiation-induced heart injury. Results of the study indicate that the damage is secondary to radiation-induced changes of the vascula connective tissue.

Preparation of inorganic crystalline compounds induced by ionizing, UV and laser radiation

International Nuclear Information System (INIS)

Cuba, V.; Pavelkova, T.; Barta, J.; Indrei, J.; Gbur, T.; Pospisil, M.; Mucka, V.; Docekalova, Z.; Zavadilova, A.; Vlk, M.

2011-01-01

Complete text of publication follows. Radiation methods represent powerful tool for synthesis of various inorganic materials. Study of solid particles formation from solutions in the field of UV or ionizing radiation is one of the very promising and long term pursued trends in photochemistry and radiation chemistry. The motivation may be various, either preparation of new materials or removal of hazardous contaminants (e.g. heavy metals) from wastewater. This work deals with preparation of some metal oxides, synthetic garnets and spinel structures via irradiation of aqueous solutions containing precursors, i.e. soluble metal salts, radical scavengers and/or macromolecular stabilizers. Namely, results on radiation induced preparation of nickel, zinc, yttrium and aluminium oxides are summarized, as well as zinc peroxide, yttrium / lutetium - aluminium garnets and cobalt(II) aluminate. 60 Co irradiator, linear electron accelerator, medium pressure UV lamp and solid state laser were used as the sources of radiation. Aside from preparation, various physico-chemical and structural properties of compounds prepared were also studied. All used modifications of radiation method are rather convenient and simple, and yield (nano)powder materials with interesting characteristics. Prepared materials generally have high chemical purity, high specific surface area and narrow distribution of particles size (ranging in tens of nm). Generally, all types of irradiation result in materials with comparable properties and structural characteristics; but in the case of synthetic garnets and spinels, preparation using UV-radiation seems to be the most convenient for their preparation. Among compounds discussed, only zinc oxide and zinc peroxide were prepared directly via irradiation. For preparation of other crystalline compounds, additional heat treatment (at low temperature) of amorphous solid phase formed under irradiation was necessary.

Measurement of OH free radical in magnetized sheet plasma crossed with vertical gas-flow by laser-induced fluorescence spectroscopy

International Nuclear Information System (INIS)

Tonegawa, Akira; Takatori, Masahiko; Kobayashi, Yukihiro; Kawamura, Kazutaka; Takayama, Kazuo

1997-01-01

We demonstrated the production of OH free radicals in an argon magnetized sheet plasma crossed with vertical gas-flow mixed with an oxygen gas O 2 and a hydrogen gas H 2 . The density and the rotational-vibrational temperature of the OH free radicals were measured by a laser-induced fluorescence (LIF). The density of OH free radicals increases with increasing O 2 gas-flow, while the high energy part of the electron-energy-distribution-function f e (E) above 8 eV decreases. These results suggest the high energy part of f e (E) is contributed to the dissociation of O 2 and the production of OH free radicals. (author)

Complications of combined radical hysterectomy-postoperative radiation therapy in women with early stage cervical cancer

International Nuclear Information System (INIS)

Barter, J.F.; Soong, S.J.; Shingleton, H.M.; Hatch, K.D.; Orr, J.W. Jr.

1989-01-01

Fifty patients with cervical cancer were treated with radical hysterectomy and lymphadenectomy followed by postoperative radiation therapy for high risk factors (nodal metastases, lymphvascular space invasion, close or involved margins) at the University of Alabama at Birmingham Medical Center from 1969 to 1984. Fifteen (30%) of the patients treated had serious complications, 8 (16%) requiring an operation, and 1 (2%) dying as a result of treatment-related problems. This combined modality approach is associated with significant complications

Radiation induced cerebellum impairments in Swiss albino mice and its modulation by dietary Prunus domestica

International Nuclear Information System (INIS)

Sharma, Garima; Sisodia, Rashmi

2012-01-01

To study the biochemical, quantitative histopathological and behavioural changes after 5 Gy whole body irradiation and its modulation by supplementation of Prunus domestica extract (PDE) for 15 consecutive days on male Swiss albino. For this study healthy mice from an inbred colony were divided into five groups: (i) Control; (ii) PDE treated - mice in this group were orally supplemented with PDE (400 mg/kg body weight (bw)/day) once daily for 15 consecutive days; (iii) Irradiated-mice were whole body exposed to 5 Gy irradiated; (iv) PDE + irradiated-mice in this group were orally supplemented PDE for 15 days (once a day) prior to irradiation; and (v) irradiated+PDE -mice in this group were administered PDE orally for 15 days (once a day) consequently after irradiation. Marked radiation induced changes in the amount of cerebellar lipid peroxidation (LPO), glutathione (GSH), protein, superoxide dismutase (SOD), catalase and histopathological changes (molecular layer, granular layer and purkinje cell numbers) could be significantly ameliorated supplementation of PDE prior/post irradiation. Radiation induced deficits in learning and memory were also significantly ameliorated. PDE was found to have strong radical scavenging activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and also showed in vitro radioprotective activity. The result of present study showed that prior/post-supplementation of Prunus domestica has radioprotective potential as well as neuroprotective properties against the radiation. (author)

Radiation-induced degradation of pollutants

International Nuclear Information System (INIS)

Proksch, E.

1988-01-01

This article outlines the fundamentals of radiation-induced degradation of noxious substances in drinking water and waste water and discusses the relevant literature. Radiation methods present a number of advantages and disadvantages, which should carefully be considered in each case. In many cases, there seems to be merit in combining the radiation method with other techniques, as e.g. ozone treatement and biodegradation. 30 refs., 3 figs. (Author)

Radiation-induced transformations of isolated organic molecules in solid rare gas matrices

International Nuclear Information System (INIS)

Feldman, V.I.

1998-01-01

Complete text of publication follows. The studies of radiation-chemical behaviour of isolated organic molecules in rigid inert media are of considerable interest for radiation chemistry and general structural chemistry. Previous efforts were limited to the ESR studies of radicals resulting from some small hydrocarbon molecules in frozen rare gas solutions. Recently, we developed an approach to the radiation chemistry of isolated organic molecules using classic matrix isolation procedure for sample preparation and a combination of ESR and IR spectroscopy for characterization of paramagnetic and diamagnetic species resulting form electron irradiation or organic molecules in solid rare gas matrices at 10-15 K. The results obtained reveal high efficiency of energy transfer from rare gas matrix to organic molecules. The total radiation-chemical yields of degradation of organic molecules in argon and xenon matrices were measured directly by IR spectroscopy. The studies of the effect of electron scavengers on the radiolysis of organic molecules in solid rare gases show that the main primary process is positive hole transfer from matrix to additive molecule. ESR spectra of a number of radical cations (alkanes, ethers, arenes) were first characterized in a low-disturbing environment. It was found that the electronic characteristics (IP, polarizability) of the matrix used had crucial effect on trapping and degradation of primary organic radical cations. Using matrices with various IP provides an unique possibility to examine the chemical meaning of excess energy resulting from exothermic positive hole transfer, that is, to follow the fate of excited cations in condensed phase

Radiation-induced crosslinking of syndiotactic 1,2-polybutadiene

International Nuclear Information System (INIS)

Iwai, Tadashi; Hoshino, Sadao; Yamamoto, Rokuro; Okamoto, Hidemasa; Obana, Kazuyoshi.

1978-01-01

Crystalline syndiotactic 1, 2-polybutadiene (hereafter abbreviated as 1, 2-PB) developed in Ube Industries, Ltd. by its own technology is a new thermoplastic resin belonging to the intermediate region between rubber and plastics in its flexibility. By selecting appropriate catalyst composition, 1, 2-PB having the melting point of 90 to 200 deg. C and crystallization of 10 to 65% can be obtained. These 1, 2-PBs can be worked to formed products by general thermoplastic forming methods such as injection molding, extrusion forming and blow forming. Radiation-crosslinked 1, 2-PB changed to very hard polymers through heat treatment. This change has been found to be radical chain reaction of cyclic polymerization. The relation of radiation-induced crosslinking and thermal expansion behavior, and the changes of appearance and structural and physical properties with heat treatment of these polymers are described. That is, specific gravity has increased, tensile strength has been enhanced, and elongation has decreased. While dielectric strength and arc resistivity have been upgraded. Therefore, these polymers can be used for the following applications: food wrapping film, molded notions, molded low foaming material for the soles of footwears, highly foaming moldings such as sponges, electric insulation material such as cable coating and adhesives for many materials. It is considered that crosslinking contributes to the application to electric insulation materials and heat curing to heat-resistant materials and parts. (Wakatsuki, Y.)

Amelioration of radiation stress by antioxidants and prooxidants: role of redox transcription factors

International Nuclear Information System (INIS)

Sandur, Santosh Kumar

2011-01-01

The development of radiation countermeasures has emerged as a major area of research in radiation biology as ionizing radiation is finding wide applications in power generation, agriculture, food processing, disease diagnosis and therapy. Chemical agents used to alter tissue toxicity of radiation can be broadly divided into three categories based on the time of intervention in relation to radiation. These are: radioprotectors, mitigators, and therapeutic agents. Radiation causes injury to normal tissue by a dynamic process involving generation of reactive oxygen species (ROS), their interactions with bio-molecules, intracellular signaling, cell-to-cell communication, inflammatory responses, tissue repair and cell death. Most of the radiation-induced damage to bio-molecules is caused by the formation of free radicals resulting from the radiolysis of water. However, antioxidants that neutralize free radicals failed to reach clinic. At present, no agent, approved by the U.S. Food and Drug Administration, is available for the treatment of acute radiation syndrome (ARS), although amifostine is approved for prophylaxis of dry mouth (xerostomia) from radiotherapy of head and neck cancers. Therefore, researchers are employing new approaches to ameliorate radiation induced injury. Some of these include use of cytokines, NF-κB (Nuclear factor κB) activators, agents that induce G1 arrest, antibiotics and inhibitors of P53. We have used pro-oxidants to upregulate cytoprotective pathways as a novel strategy to protect against radiation induced hematopoietic syndrome. Different prooxidants including hydrogen peroxide, diethylmaleate, t-butylhydroperoxide and naphthoquinone and its derivatives protected lymphocytes against radiation induced cell death. Further studies were carried out with 1,4-naphthoquinone (NQ) to explore the molecular mechanism of the observed protection. Thiol containing antioxidants abrogated NQ mediated radioprotection in lymphocytes. Addition of NQ to

Some reactions of oxidizing radicals with enzymes in aqueous solution

International Nuclear Information System (INIS)

Cundall, R.B.; Bisby, R.H.; Hoe, S.T.; Sims, H.E.; Anderson, R.F.

1979-01-01

A range of oxidizing radicals including some inorganic radical anions and the superoxide radical, can be generated by radiolysis of aqueous solutions. These radicals are more selective in their reactions with amino acids than the hydroxyl radical. Factors controlling the apparent reactivity of radical anions with proteins, such as free radical equilibria and ion-binding, are described. The superoxide radical inactivates papain by reaction with the cysteine residue. This reaction has been studied in solutions subjected to radiations of varying linear energy transfer. (Auth.)

Pyruvate metabolism: A therapeutic opportunity in radiation-induced skin injury

Energy Technology Data Exchange (ETDEWEB)

Yoo, Hyun; Kang, Jeong Wook [Department of Radiation Oncology, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Lee, Dong Won [Department of Plastic Surgery, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Oh, Sang Ho [Department of Dermatology, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Lee, Yun-Sil [College of Pharmacy & Division of Life and Pharmaceutical Sciences, Ewah Womans University, Seoul 120-750 (Korea, Republic of); Lee, Eun-Jung [Department of Radiation Oncology, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Cho, Jaeho, E-mail: jjhmd@yuhs.ac [Department of Radiation Oncology, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of)

2015-05-08

Ionizing radiation is used to treat a range of cancers. Despite recent technological progress, radiation therapy can damage the skin at the administration site. The specific molecular mechanisms involved in this effect have not been fully characterized. In this study, the effects of pyruvate, on radiation-induced skin injury were investigated, including the role of the pyruvate dehydrogenase kinase 2 (PDK2) signaling pathway. Next generation sequencing (NGS) identified a wide range of gene expression differences between the control and irradiated mice, including reduced expression of PDK2. This was confirmed using Q-PCR. Cell culture studies demonstrated that PDK2 overexpression and a high cellular pyruvate concentration inhibited radiation-induced cytokine expression. Immunohistochemical studies demonstrated radiation-induced skin thickening and gene expression changes. Oral pyruvate treatment markedly downregulated radiation-induced changes in skin thickness and inflammatory cytokine expression. These findings indicated that regulation of the pyruvate metabolic pathway could provide an effective approach to the control of radiation-induced skin damage. - Highlights: • The effects of radiation on skin thickness in mice. • Next generation sequencing revealed that radiation inhibited pyruvate dehydrogenase kinase 2 expression. • PDK2 inhibited irradiation-induced cytokine gene expression. • Oral pyruvate treatment markedly downregulated radiation-induced changes in skin thickness.

Effect of radiation on Poly Vinyl chloride (PVC)

International Nuclear Information System (INIS)

Massaud, F.; Haraga, S.; Benfaid, N.; Benayad, S.; Kabar, Y.; Elmesmary, Y; Elwerfeli, M.; Omran, Sh.

1993-01-01

Radiation crosslinking of polymeric materials is of increasing commercial importance because of the improved thermal, electrical and mechanical properties. Poly Vinylchloride (PVC) is one of the most important polymers. Many attempts were made to study the primary reactions induced by the direct effect of radiation on PVC. In this study, powder PVC was irradiated with different doses at ambient temperature. Formation of free radicals was investigated by electron spin resonance (ESR) method and molecular weight was determined by viscosity measurements. It has been observed that hydrogen chloride was evolved because of noticeable change in color. One type of radical, Poly enyl structure was trapped at room temperature. The non-symmetric singlet structure of the ESR spectra is due to the presence of oxygen. The radical concentration increased with increase of dose. The molecular weight of irradiated PVC was found to be inversely proportional to the increase of radiation dose, which is believed to be due to the occurrence of degradation. It can be concluded that gamma radiation will be the best method for crosslinking of PVC if multi-functional groups or monomers are present. (author)

Radiation-induced reduction and mineralization of cephalosporins

International Nuclear Information System (INIS)

Yu Seungho; Lee Myunjoo; Lee Byungjin

2006-01-01

Reports in the literature show that pharmaceuticals used in human and animal husbandry are present in soil, sediment, surface water, and groundwater. Cephalosporin belongs to a group of β-lactam antibiotics active against bacteria by interfering with the ability of bacteria to form cell walls, and is one of the widely used antibiotics in today's human medicine practice. For the study of cephalosporin oxidation by radiation, irradiations were performed with a 60 Co source available at Korea Atomic Energy Research Institute in Korea. 30 mg/L and 50 mg/L of Cefaclor and Cephradine in solution, respectively, were irradiated at 0-100 kGy. Both antibiotics were completely transformed into the byproducts at 600 Gy. No differences in results were found after purging with N 2 and O 2 gases, respectively. However, maximum 20% of COD and TOC were removed with N 2 purged, while more than 60% with O 2 purged at lower than 10 kGy. Almost 100% removal efficiency was obtained with O 2 purged at 100 kGy. In order to investigate the effect of various radicals produced, methanol and thiourea were used as radical scavengers. The experimental results showed that ·OH radical was mainly responsible for the oxidation of Cephaolosporins. (authors)

Radiation-induced Genomic Instability and Radiation Sensitivity

Energy Technology Data Exchange (ETDEWEB)

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

2013-01-19

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

Radiation-Induced Differentiation in Human Lung Fibroblast

International Nuclear Information System (INIS)

Park, Sa-Rah; Ahn, Ji-Yeon; Han, Young-Soo; Shim, Jie-Young; Yun, Yeon-Sook; Song, Jie-Young

2007-01-01

One of the most common tumors in many countries is lung cancer and patients with lung cancer may take radiotherapy. Although radiotherapy may have its own advantages, it can also induce serious problems such as acute radiation pneumonitis and pulmonary fibrosis. Pulmonary fibrosis is characterized by excessive production of α-SMA and accumulation of extracellular matrix (ECM) such as collagen and fibronectin. There has been a great amount of research about fibrosis but the exact mechanism causing the reaction is not elucidated especially in radiation-induced fibrosis. Until now it has been known that several factors such as transforming growth factor (TGF-β), tumor necrosis factor (TNF), interleukin (IL)-1, IL-6, platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) are related to fibrosis. Among them TGF-β with Smad signaling is known to be the main stream and other signaling molecules such as MAPK, ERK and JNK (3) also participates in the process. In addition to those above factors, it is thought that more diverse and complicate mechanisms may involve in the radiationinduced fibrosis. Therefore, to investigate the underlying mechanisms in radiation induced fibrosis, first of all, we confirmed whether radiation induces trans differentiation in human normal lung fibroblasts. Here, we suggest that not only TGF-β but also radiation can induce trans differentiation in human lung fibroblast WI-38 and IMR-90

Evaluation of Radio-Protective Effect of Melatonin on Whole Body Irradiation Induced Liver Tissue Damage

NARCIS (Netherlands)

Shirazi, Alireza; Mihandoost, Ehsan; Ghobadi, Ghazaleh; Mohseni, Mehran; Ghazi-Khansari, Mahmoud

2013-01-01

Objective: Ionizing radiation interacts with biological systems to induce excessive fluxes of free radicals that attack various cellular components. Melatonin has been shown to be a direct free radical scavenger and indirect antioxidant via its stimulatory actions on the antioxidant system. The aim

Radiation-induced damage in T4 bacteriophage: the effect of superoxid radicals and molecular oxygen. Progress report, December 1, 1977--November 30, 1978

International Nuclear Information System (INIS)