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1

Radiation-Induced Amorphization of Crystalline Ice  

NASA Technical Reports Server (NTRS)

We study radiation-induced amorphization of crystalline ice, ana lyzing the resu lts of three decades of experiments with a variety of projectiles, irradiation energy, and ice temperature, finding a similar trend of increasing resistance of amorphization with temperature and inconsistencies in results from different laboratories. We discuss the temperature dependence of amorphization in terms of the 'thermal spike' model. We then discuss the common use of the 1.65 micrometer infrared absorption band of water as a measure of degree of crystallinity, an increasingly common procedure to analyze remote sensing data of astronomical icy bodies. The discussion is based on new, high quality near-infrared refl ectance absorption spectra measured between 1.4 and 2.2 micrometers for amorphous and crystalline ices irradiated with 225 keV protons at 80 K. We found that, after irradiation with 10(exp 15) protons per square centimeter, crystalline ice films thinner than the ion range become fully amorphous, and that the infrared absorption spectra show no significant changes upon further irradiation. The complete amorphization suggests that crystalline ice observed in the outer Solar System, including trans-neptunian objects, may results from heat from internal sources or from the impact of icy meteorites or comets.

Fama, M.; Loeffler, M. J.; Raut, U.; Baragiola, R. A.

2009-01-01

2

Tryptophan Cluster Protects Human ?D-Crystallin from Ultraviolet Radiation-Induced Photoaggregation  

E-print Network

Exposure to ultraviolet radiation (UVR) is a significant risk factor for age-related cataract, a disease of the human lens and the most prevalent cause of blindness in the world. Cataract pathology involves protein misfolding ...

Schafheimer, Steven Nathaniel

3

Tyrosine/Cysteine Cluster Sensitizing Human ?D-Crystallin to Ultraviolet Radiation-Induced Photoaggregation in Vitro  

PubMed Central

Ultraviolet radiation (UVR) exposure is a major risk factor for age-related cataract, a protein-aggregation disease of the human lens often involving the major proteins of the lens, the crystallins. ?D-Crystallin (H?D-Crys) is abundant in the nucleus of the human lens, and its folding and aggregation have been extensively studied. Previous work showed that H?D-Crys photoaggregates in vitro upon exposure to UVA/UVB light and that its conserved tryptophans are not required for aggregation. Surprisingly, the tryptophan residues play a photoprotective role because of a distinctive energy-transfer mechanism. H?D-Crys also contains 14 tyrosine residues, 12 of which are organized as six pairs. We investigated the role of the tyrosines of H?D-Crys by replacing pairs with alanines and monitoring photoaggregation using light scattering and SDS-PAGE. Mutating both tyrosines in the Y16/Y28 pair to alanine slowed the formation of light-scattering aggregates. Further mutant studies implicated Y16 as important for photoaggregation. Mass spectrometry revealed that C18, in contact with Y16, is heavily oxidized during UVR exposure. Analysis of multiple mutant proteins by mass spectrometry suggested that Y16 and C18 likely participate in the same photochemical process. The data suggest an initial photoaggregation pathway for H?D-Crys in which excited-state Y16 interacts with C18, initiating radical polymerization. PMID:24410332

2015-01-01

4

High pulse repetition frequency ultrasound system for ex vivo measurement of mechanical properties of crystalline lenses with laser-induced microbubble interrogated by acoustic radiation force  

PubMed Central

A high pulse repetition frequency ultrasound system for ex vivo measurement of mechanical properties of animal crystalline lens was developed and validated. We measured the bulk displacement of laser-induced microbubbles created at different positions within the lens using nanosecond laser pulses. An impulsive acoustic radiation force was applied to the microbubble, and spatio-temporal measurements of the microbubble displacement were assessed using a custom-made high pulse repetition frequency ultrasound system consisting of two 25 MHz focused ultrasound transducers. One of these transducers was used to emit a train of ultrasound pulses and another transducer was used to receive the ultrasound echoes reflected from the microbubble. The developed system was operating at 1 MHz pulse repetition frequency. Based on measured motion of the microbubble, the Young’s moduli of surrounding tissue were reconstructed and the values were compared with those measured using indentation test. Measured values of Young’s moduli of 4 bovine lenses ranged from 2.6±0.1 to 26±1.4 kPa and there was good agreement between the two methods. Therefore, our studies, utilizing the high pulse repetition frequency ultrasound system, suggest that the developed approach can be used to assess the mechanical properties of ex vivo crystalline lenses. Furthermore, the potential of the presented approach for in vivo measurements is discussed. PMID:22797709

Yoon, Sangpil; Aglyamov, Salavat; Karpiouk, Andrei; Emelianov, Stanislav

2012-01-01

5

UV-radiation Induced Disruption of Dry-Cavities in Human ?D-crystallin Results in Decreased Stability and Faster Unfolding  

PubMed Central

Age-onset cataracts are believed to be expedited by the accumulation of UV-damaged human ?D-crystallins in the eye lens. Here we show with molecular dynamics simulations that the stability of ?D-crystallin is greatly reduced by the conversion of tryptophan to kynurenine due to UV-radiation, consistent with previous experimental evidences. Furthermore, our atomic-detailed results reveal that kynurenine attracts more waters and other polar sidechains due to its additional amino and carbonyl groups on the damaged tryptophan sidechain, thus breaching the integrity of nearby dry center regions formed by the two Greek key motifs in each domain. The damaged tryptophan residues cause large fluctuations in the Tyr-Trp-Tyr sandwich-like hydrophobic clusters, which in turn break crucial hydrogen-bonds bridging two ?-strands in the Greek key motifs at the “tyrosine corner”. Our findings may provide new insights for understanding of the molecular mechanism of the initial stages of UV-induced cataractogenesis. PMID:23532089

Xia, Zhen; Yang, Zaixing; Huynh, Tien; King, Jonathan A.; Zhou, Ruhong

2013-01-01

6

Radiation-induced graft copolymerization of methyl methacrylate on natural and modified wool. V. Crystalline and morphological structure. [. gamma. -rays  

SciTech Connect

X-ray diffraction patterns of the ..cap alpha..- and ..beta..-crystalline phases of natural, chemically modified, and MMA-grafted wool fibers were investigated. In the grafted fibers variation of the equatorial and meridional scattering intensity during the ..cap alpha..-..beta.. transformation was inhibited. This indicated that the grafting had stabilized the structure to the ..cap alpha..-..beta.. transformation. The average crystallite size was found to increase with the extent of grafting, and the degree of orientation appeared to decrease with percent graft-on. SEM studies revealed little damage to the surface topography of wool fibers after chemical treatments. Graft copolymerization with MMA made the fiber surface regular and smooth, mainly because of deposition of polymer in the escarpment, thus reducing the sharpness of the scaly structure. Scanning electron micrographs of the peeled-off surface and cross sections of the grafted fibers indicated that a significant amount of polymer was deposited in the medullae of the fibers.

Varma, D.S.; Sadhir, R.K.

1980-03-01

7

Light-induced liquid crystallinity.  

PubMed

Liquid crystals are traditionally classified as thermotropic, lyotropic or polymeric, based on the stimulus that governs the organization and order of the molecular system. The most widely known and applied class of liquid crystals are a subset of thermotropic liquid crystals known as calamitic, in which adding heat can result in phase transitions from or into the nematic, cholesteric and smectic mesophases. Photoresponsive liquid-crystal materials and mixtures can undergo isothermal phase transitions if light affects the order parameter of the system within a mesophase sufficiently. In nearly all previous examinations, light exposure of photoresponsive liquid-crystal materials and mixtures resulted in order-decreasing photo-induced isothermal phase transitions. Under specialized conditions, an increase in order with light exposure has been reported, despite the tendency of the photoresponsive liquid-crystal system to reduce order in the exposed state. A direct, photo-induced transition from the isotropic to the nematic phase has been observed in a mixture of spiropyran molecules and a nematic liquid crystal. Here we report a class of naphthopyran-based materials that exhibit photo-induced conformational changes in molecular structure capable of yielding order-increasing phase transitions. Appropriate functionalization of the naphthopyran molecules leads to an exceedingly large order parameter in the open form, which results in a clear to strongly absorbing dichroic state. The increase in order with light exposure has profound implications in optics, photonics, lasing and displays and will merit further consideration for applications in solar energy harvesting. The large, photo-induced dichroism exhibited by the material system has been long sought in ophthalmic applications such as photochromic and polarized variable transmission sunglasses. PMID:22596158

Kosa, Tamas; Sukhomlinova, Ludmila; Su, Linli; Taheri, Bahman; White, Timothy J; Bunning, Timothy J

2012-05-17

8

The influence of crystallinity on radiation stability of UHMWPE  

NASA Astrophysics Data System (ADS)

The influence of ionizing radiation on ultra high molecular weight polyethylene (UHMWPE) was studied using EPR spectroscopy and GC. Two samples of various degree of crystallinity, 85% and 53%, were investigated upon exposure to electron beam. In this study it was found that radicals generated following irradiation decay much faster in amorphous than in crystalline phase. The primary product generated in both phases is second ordered alkyl radical. EPR spectra detected for the sample containing 85% crystalline regions revealed a quintet of hyperfine splitting about 2.28 mT and the signal was tentatively assigned to the product of ?-fragmentation. The radiation yield of hydrogen for two studied samples of various crystallinity was similar.

Kornacka, Ewa Maria; Przybytniak, Gra?yna; ?wi?szkowski, Wojciech

2013-03-01

9

UV-radiation Induced Disruption of Dry-Cavities in Human ?D-crystallin Results in Decreased Stability and Faster Unfolding  

E-print Network

Age-onset cataracts are believed to be expedited by the accumulation of UV-damaged human ?D-crystallins in the eye lens. Here we show with molecular dynamics simulations that the stability of ?D-crystallin is greatly reduced ...

Xia, Zhen

10

Analysis of strain-induced crystallinity in neutron-irradiated amorphous PET fiber  

NASA Astrophysics Data System (ADS)

Polyethylene terephthalate (PET) fiber of 2.2 denier per filament has been irradiated with 4.44-MeV fast neutron beam at different low doses: 0.58-2,513.5 mGy. The variation of crystallinity because of neutron irradiation straining in PET filaments has been investigated. Study of the effects of irradiation by using X-ray diffraction and differential scanning calorimetry technique confirms the radiation-induced microstrain-dependent crystallinity of PET fiber.

Mallick, B.

2015-03-01

11

Locating microearthquakes induced by hydraulic fracturing in crystalline rock  

Microsoft Academic Search

Microearthquakes induced by hydraulic fracturing in crystalline rock at a depth of 3.5 km were located with a precision of better than 30 m to obtain information about the geometry and dimensions of the fracture system produced. The induced microseismicity was monitored by a network of five vorehole seismic stations; a total of about 800 induced events were reliably located

Leigh House

1987-01-01

12

Radiation stability test on multiphase glass ceramic and crystalline ceramic waste forms  

NASA Astrophysics Data System (ADS)

A radiation stability study was performed on glass ceramic and crystalline ceramic waste forms. These materials are candidate host materials for immobilizing alkali/alkaline earth (Cs/Sr-CS) + lanthanide (LN) + transition metal (TM) fission product waste streams from nuclear fuel reprocessing. In this study, glass ceramics were fabricated using a borosilicate glass as a matrix in which to incorporate CS/LN/TM combined waste streams. The major phases in these multiphase materials are powellite, oxyaptite, pollucite, celsian, and durable residual glass phases. Al2O3 and TiO2 were combined with these waste components to produce multiphase crystalline ceramics containing hollandite-type phases, perovskites, pyrochlores and other minor metal titanate phases. For the radiation stability test, selected glass ceramic and crystalline ceramic samples were exposed to different irradiation environments including low fluxes of high-energy (?1-5 MeV) protons and alpha particles generated by an ion accelerator, high fluxes of low-energy (hundreds of keV) krypton particles generated by an ion implanter, and in-situ electron irradiations in a transmission electron microscope. These irradiation experiments were performed to simulate self-radiation effects in a waste form. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction and transmission electron microscopy. Our preliminary results reveal different radiation tolerance in different crystalline phases under various radiation damage environments. However, their stability may be rate dependent which may limit the waste loading that can be achieved.

Tang, Ming; Kossoy, Anna; Jarvinen, Gordon; Crum, Jarrod; Turo, Laura; Riley, Brian; Brinkman, Kyle; Fox, Kevin; Amoroso, Jake; Marra, James

2014-05-01

13

The radiation damage of crystalline silicon PN diode in tritium beta-voltaic battery.  

PubMed

A tritium beta-voltaic battery using a crystalline silicon convertor composed of (100)Si/SiO2/Si3N4 film degrades remarkably with radiation from a high intensity titanium tritide film. Simulation and experiments were carried out to investigate the main factor causing the degradation. The radiation damages mainly comes from the x-ray emitted from the titanium tritide film and beta particle can relieve the damages. The x-ray radiation induced positive charges in the SiO2 film destroying the output property of the PN diode with the induction of an electric field. PMID:24751350

Lei, Yisong; Yang, Yuqing; Liu, Yebing; Li, Hao; Wang, Guanquan; Hu, Rui; Xiong, Xiaoling; Luo, Shunzhong

2014-08-01

14

Radiation-induced pneumothorax  

SciTech Connect

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.

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

1983-01-01

15

Radiation-induced ignition  

SciTech Connect

The effects of gas-phase radiation absorption on radiative ignition of various combustible materials under gravity conditions are studied. The physical models in this study range from a simple gas layer to a complex porous structure. Methyl methacrylate (MMA: C{sub 5}H{sub 8}O{sub 2}) vapor has been selected as a representative of participating gases in gas-phase radiation interactions. Its infrared radiation properties were measured using low-resolution spectral apparatus and then correlated in simple usable forms. As expected from its complex molecular structure, the infrared absorption capabilities of MMA vapor is much stronger than those of simpler hydrocarbon gases as well as water vapor and carbon dioxide. Radiation induced ignition was analyzed on the basis of simple theoretical models. Using Semenov's theory, results indicate a decrease in the critical surrounding temperature for a low Biot number system. For a high Biot number system, ignitability is defined through the use of Frank-Kamenetskii's critical parameter delta. One-dimensional transient models were developed for the analyses of radiation induced ignition of solid and porous solid fuels. The models include gas-phase radiation absorption, in-depth radiation interaction by the solid phase, Arrhenius-type chemical reaction, and natural convection. Predicted transmittance during ignition processes confirms the attenuation of incident radiation by pyrolyzed gases which has been already observed experimentally. An ignition process with gas-phase radiation absorption results in a quite different and widened ignition domain compared to that without gas-phase radiation absorption. Moreover, ignition is totally dependent on gas-phase radiation absorption under unfavorable conditions for a thermal runaway.

Park, S.

1989-01-01

16

Radiation-induced sarcoma  

Microsoft Academic Search

Opinion statement  Radiation-induced sarcomas can originate in either the irradiated bone or soft tissues. Most of these tumors are high-grade.\\u000a The most common histologic subtypes are malignant fibrous histiocytoma (MFH) and osteosarcoma, although other histologies\\u000a (eg, angiosarcoma, rhabdomyosarcoma) can occur. Tumor size and grade are the two most important prognostic factors for soft tissue\\u000a sarcomas, including those associated with radiation therapy.

Shreyaskumar R. Patel

2000-01-01

17

Growth Induced Magnetic Anisotropy in Crystalline and Amorphous Thin Films  

SciTech Connect

OAK B204 Growth Induced Magnetic Anisotropy in Crystalline and Amorphous Thin Films. The work in the past 6 months has involved three areas of magnetic thin films: (1) amorphous rare earth-transition metal alloys, (2) epitaxial Co-Pt and hTi-Pt alloy thin films, and (3) collaborative work on heat capacity measurements of magnetic thin films, including nanoparticles and CMR materials.

Hellman, Frances

1998-10-03

18

Radiation-Induced Bioradicals  

NASA Astrophysics Data System (ADS)

This chapter represents the second part of a review in which the production and application of radiation-induced radicals in biological matter are discussed. In part one the general aspects of the four stages (physical, physicochemical, chemical and biological) of interaction of radiation with matter in general and biological matter in particular, were discussed. Here an overview is presented of modem technologies and theoretical methods available for studying these radiation effects. The relevance is highlighted of electron paramagnetic resonance spectroscopy and quantum chemical calculations with respect to obtaining structural information on bioradicals, and a survey is given of the research studies in this field. We also discuss some basic aspects of modem accelerator technologies which can be used for creating radicals and we conclude with an overview of applications of radiation processing in biology and related fields such as biomedical and environmental engineering, food technology, medicine and pharmacy.

Lahorte, Philippe; Mondelaers, Wim

19

Surfactant-induced postsynthetic modulation of Pd nanoparticle crystallinity.  

SciTech Connect

Modulation of Pd nanoparticle (NP) crystallinity is achieved by switching the surfactants of different binding strengths. Pd NPs synthesized in the presence of weak binding surfactants such as oleylamine possess polyhedral shapes and a polycrystalline nature. When oleylamine is substituted by trioctylphosphine, a much stronger binding surfactant, the particles become spherical and their crystallinity decreases significantly. Moreover, the Pd NPs reconvert their polycrystalline structure when the surfactant is switched back to oleylamine. Through control experiments and molecular dynamics simulation, we propose that this unusual nanocrystallinity transition induced by surfactant exchange was resulted from a counterbalance between the surfactant binding energy and the nanocrystal adhesive energy. The findings represent a novel postsynthetic approach to tailoring the structure and corresponding functional performance of nanomaterials.

Liu, Y.; Wang, C.; Wei, Y.; Zhu, L.; Li, D.; Jiang, J. S.; Markovic, N. M.; Stamenkovic, V. R.; Sun, S. (Materials Science Division); (Brown Univ.); (Chinese Academy of Sciences)

2011-02-01

20

Radiation induced oral mucositis.  

PubMed

PATIENTS RECEIVING RADIOTHERAPY OR CHEMOTHERAPY WILL RECEIVE SOME DEGREE OF ORAL MUCOSITIS THE INCIDENCE OF ORAL MUCOSITIS WAS ESPECIALLY HIGH IN PATIENTS: (i) With primary tumors in the oral cavity, oropharynx, or nasopharynx; (ii) who also received concomitant chemotherapy; (iii) who received a total dose over 5,000 cGy; and (iv) who were treated with altered fractionation radiation schedules. Radiation-induced oral mucositis affects the quality of life of the patients and the family concerned. The present day management of oral mucositis is mostly palliative and or supportive care. The newer guidelines are suggesting Palifermin, which is the first active mucositis drug as well as Amifostine, for radiation protection and cryotherapy. The current management should focus more on palliative measures, such as pain management, nutritional support, and maintenance, of good oral hygiene. PMID:20668585

Ps, Satheesh Kumar; Balan, Anita; Sankar, Arun; Bose, Tinky

2009-07-01

21

Radiation Induced Genomic Instability  

SciTech Connect

Radiation induced genomic instability can be observed in the progeny of irradiated cells multiple generations after irradiation of parental cells. The phenotype is well established both in vivo (Morgan 2003) and in vitro (Morgan 2003), and may be critical in radiation carcinogenesis (Little 2000, Huang et al. 2003). Instability can be induced by both the deposition of energy in irradiated cells as well as by signals transmitted by irradiated (targeted) cells to non-irradiated (non-targeted) cells (Kadhim et al. 1992, Lorimore et al. 1998). Thus both targeted and non-targeted cells can pass on the legacy of radiation to their progeny. However the radiation induced events and cellular processes that respond to both targeted and non-targeted radiation effects that lead to the unstable phenotype remain elusive. The cell system we have used to study radiation induced genomic instability utilizes human hamster GM10115 cells. These cells have a single copy of human chromosome 4 in a background of hamster chromosomes. Instability is evaluated in the clonal progeny of irradiated cells and a clone is considered unstable if it contains three or more metaphase sub-populations involving unique rearrangements of the human chromosome (Marder and Morgan 1993). Many of these unstable clones have been maintained in culture for many years and have been extensively characterized. As initially described by Clutton et al., (Clutton et al. 1996) many of our unstable clones exhibit persistently elevated levels of reactive oxygen species (Limoli et al. 2003), which appear to be due dysfunctional mitochondria (Kim et al. 2006, Kim et al. 2006). Interestingly, but perhaps not surprisingly, our unstable clones do not demonstrate a “mutator phenotype” (Limoli et al. 1997), but they do continue to rearrange their genomes for many years. The limiting factor with this system is the target – the human chromosome. While some clones demonstrate amplification of this chromosome and thus lend themselves to prolonged study, many tend to eliminate or rearrange the target chromosome until it is too small for further rearrangement. The observed frequency of induced instability by low and high linear-energy-transfer radiations greatly exceeds that observed for nuclear gene mutations at similar doses; hence, mutation of a gene or gene family is unlikely to be the initiating mechanism. Once initiated however, there is evidence in the GM10115 model system that it can be perpetuated over time by dicentric chromosome formation followed by bridge breakage fusion cycles (Marder and Morgan 1993), as well as recombinational events involving interstitial telomere like repeat sequences (Day et al. 1998). There is also increasing evidence that inflammatory type reactions (Lorimore et al. 2001, Lorimore and Wright 2003), presumably involving reactive oxygen and nitrogen species as well as cytokines and chemokines might be involved in driving the ustable phenotype (Liaikis et al. 2007, Hei et al. 2008). To this end there is very convincing evidence for such reactions being involved in another non-targeted effect associated with ionizing radiation, the bystander effect (Hei et al. 2008). Clearly the link between induced instability and bystander effects suggests common processes and inflammatory type reactions will likely be the subject of future investigation.

Morgan, William F.

2011-03-01

22

Pressure-induced phase transition of crystalline and amorphous silicon and germanium at low temperatures  

Microsoft Academic Search

X-ray diffraction has been measured for crystalline silicon, crystalline germanium, amorphous silicon and amorphous germanium at temperatures down to 100 K and pressures up to 20 GPa using a diamond anvil cell and synchrotron radiation. The structural phase transitions, including amorphization, take place in the pressure-temperature range. It has been found that the structures after the phase transitions strongly depend

Motoharu Imai; Takeshi Mitamura; Kenichi Yaoita; Kazuhiko Tsuji

1996-01-01

23

Radiation-induced tumorigenesis.  

PubMed

During the past 2 decades, radiation tumorigenesis researchers have focused on cellular and molecular mechanisms. We reviewed some of these research fields, since they may specifically relate to the induction of cancer by ionizing radiation. First, radiation-mediated mutation was discussed. Then the initiating event in radiation carcinogenesis, as well as other genetic events that may be involved, is discussed in terms of the possible role of the activation of genes and the loss of cell-cycle checkpoints. PMID:12542985

Kim, In-Gyu; Lee, Yun-Sil Lee

2003-01-31

24

The molecular chaperone alpha-crystallin inhibits UV-induced protein aggregation.  

PubMed

Solutions of gamma-crystallin, and various enzymes, at neutral pH and 24-26 degrees C, became turbid upon exposure to UV radiation at 295 or 308 nm. SDS-PAGE analysis revealed interchain cross-linking and aggregate formation compared to dark control solutions as reported previously. When alpha-crystallin was added to the protein solutions in stoichiometric amounts, UV irradiation resulted in significantly less turbidity than in the absence of alpha-crystallin. For example, addition of 0.5 mg of alpha-crystallin to 0.5 mg of gamma-crystallin in 1.0 ml solution yielded only 25% of the turbidity seen in the absence of alpha-crystallin. Addition of 2.0 mg of alpha-crystallin resulted in 20% of the turbidity. Given the molecular weights of alpha- and gamma-crystallin (about 800 kDa and 20 kDa, respectively), a gamma/alpha 1:1 weight ratio corresponds to a 40:1 molar ratio, and a gamma/alpha 1:4 weight ratio corresponds to a 10:1 molar ratio. Hence, the molar ratio of alpha-crystallin needed to effectively protect gamma-crystallin from photochemical opacification was gamma/alpha = n:1, where n was in the range 10-40. In terms of subunits, this ratio is gamma/alpha = 1:m, where m = 1-4. Thus, each gamma-crystallin molecule needs 1-4 alpha subunits for protection. Similar stoichiometries were observed for protection of the other proteins studied. The protection stems in part from screening of UV radiation by alpha-crystallin but more importantly from a chaperone effect analogous to that seen in thermal aggregation experiments. PMID:8698074

Borkman, R F; Knight, G; Obi, B

1996-02-01

25

Radiation-induced enteropathy  

SciTech Connect

The incidence of chronic radiation enteritis appears to have risen in recent years due to the increasing utilization of radiotherapy for abdominal and pelvic malignancies. The etiology, pathogenesis, and management of radiation enteritis are discussed. Two case reports exemplify the progressive nature of the disease. Case 1 demonstrates the classical picture of multiple exacerbations and remissions of partial small bowel obstruction and the eventual need for surgical management ten years after radiation therapy. Case 2 presents the more severe sequelae of an acute perforation with a 14-yr latency period. Predisposing factors in the progression of radiation injury include excessive radiation, underlying cardiovascular disease, fixation of the bowel, and an asthenic habitus. In both cases, radiation injury was localized to a discrete segment of bowel; therefore, resection with a primary end-to-end anastomosis was performed. In addition, diseased bowel was eliminated and, therefore, would not cause further complications such as intractable bleeding or fistula formation. The review focuses on current knowledge which may be applied to the treatment and prevention of radiation enteritis.

Sher, M.E.; Bauer, J. (Mount Sinai Hospital, New York, NY (USA))

1990-02-01

26

Radiation-induced genomic instability  

NASA Technical Reports Server (NTRS)

Quantitative assessment of the heritable somatic effects of ionizing radiation exposures has relied upon the assumption that radiation-induced lesions were 'fixed' in the DNA prior to the first postirradiation mitosis. Lesion conversion was thought to occur during the initial round of DNA replication or as a consequence of error-prone enzymatic processing of lesions. The standard experimental protocols for the assessment of a variety of radiation-induced endpoints (cell death, specific locus mutations, neoplastic transformation and chromosome aberrations) evaluate these various endpoints at a single snapshot in time. In contrast with the aforementioned approaches, some studies have specifically assessed radiation effects as a function of time following exposure. Evidence has accumulated in support of the hypothesis that radiation exposure induces a persistent destabilization of the genome. This instability has been observed as a delayed expression of lethal mutations, as an enhanced rate of accumulation of non-lethal heritable alterations, and as a progressive intraclonal chromosomal heterogeneity. The genetic controls and biochemical mechanisms underlying radiation-induced genomic instability have not yet been delineated. The aim is to integrate the accumulated evidence that suggests that radiation exposure has a persistent effect on the stability of the mammalian genome.

Kronenberg, A.

1994-01-01

27

?A-Crystallin Peptide 66SDRDKFVIFLDVKHF80 Accumulating in Aging Lens Impairs the Function of ?-Crystallin and Induces Lens Protein Aggregation  

PubMed Central

Background The eye lens is composed of fiber cells that are filled with ?-, ?- and ?-crystallins. The primary function of crystallins is to maintain the clarity of the lens through ordered interactions as well as through the chaperone-like function of ?-crystallin. With aging, the chaperone function of ?-crystallin decreases, with the concomitant accumulation of water-insoluble, light-scattering oligomers and crystallin-derived peptides. The role of crystallin-derived peptides in age-related lens protein aggregation and insolubilization is not understood. Methodology/Principal Findings We found that ?A-crystallin-derived peptide, 66SDRDKFVIFLDVKHF80, which accumulates in the aging lens, can inhibit the chaperone activity of ?-crystallin and cause aggregation and precipitation of lens crystallins. Age-related change in the concentration of ?A-(66-80) peptide was estimated by mass spectrometry. The interaction of the peptide with native crystallin was studied by multi-angle light scattering and fluorescence methods. High molar ratios of peptide-to-crystallin were favourable for aggregation and precipitation. Time-lapse recordings showed that, in the presence of ?A-(66-80) peptide, ?-crystallin aggregates and functions as a nucleus for protein aggregation, attracting aggregation of additional ?-, ?- and ?-crystallins. Additionally, the ?A-(66-80) peptide shares the principal properties of amyloid peptides, such as ?-sheet structure and fibril formation. Conclusions/Significance These results suggest that crystallin-derived peptides such as ?A-(66-80), generated in vivo, can induce age-related lens changes by disrupting the structure and organization of crystallins, leading to their insolubilization. The accumulation of such peptides in aging lenses may explain a novel mechanism for age-related crystallin aggregation and cataractogenesis. PMID:21552534

Santhoshkumar, Puttur; Raju, Murugesan; Sharma, K. Krishna

2011-01-01

28

Radiation effects in crystalline ceramics for the immobilization of high-level nuclear waste and plutonium  

Microsoft Academic Search

This review provides a comprehensive evaluation of the state-of-knowledge of radiation effects in crystalline ceramics that may be used for the immobilization of high-level nuclear waste and plutonium. The current understanding of radiation damage processes, defect generation, microstructure development, theoretical methods, and experimental methods are reviewed. Fundamental scientific and technological issues that offer opportunities for research are identified. The most

W. J. Weber; R. C. Ewing; C. R. A. Catlow; T. Diaz de La Rubia; L. W. Hobbs; C. Kinoshita; Hj. Matzke; A. T. Motta; M. Nastasi; E. H. K. Salje; E. R. Vance; S. J. Zinkle

1998-01-01

29

Protection of Retina by ?B Crystallin in Sodium Iodate Induced Retinal Degeneration  

PubMed Central

Age-related macular degeneration (AMD) is a leading cause of blindness in the developed world. The retinal pigment epithelium (RPE) is a critical site of pathology in AMD and ?B crystallin expression is increased in RPE and associated drusen in AMD. The purpose of this study was to investigate the role of ?B crystallin in sodium iodate (NaIO3)-induced retinal degeneration, a model of AMD in which the primary site of pathology is the RPE. Dose dependent effects of intravenous NaIO3 (20-70 mg/kg) on development of retinal degeneration (fundus photography) and RPE and retinal neuronal loss (histology) were determined in wild type and ?B crystallin knockout mice. Absence of ?B crystallin augmented retinal degeneration in low dose (20 mg/kg) NaIO3-treated mice and increased retinal cell apoptosis which was mainly localized to the RPE layer. Generation of reactive oxygen species (ROS) was observed with NaIO3 in mouse and human RPE which increased further after ?B crystallin knockout or siRNA knockdown, respectively. NaIO3 upregulated AKT phosphorylation and peroxisome proliferator–activator receptor–? (PPAR?) which was suppressed after ?B crystallin siRNA knockdown. Further, PPAR? ligand inhibited NaIO3-induced ROS generation. Our data suggest that ?B crystallin plays a critical role in protection of NaIO3-induced oxidative stress and retinal degeneration in part through upregulation of AKT phosphorylation and PPAR? expression. PMID:24874187

Zhou, Peng; Kannan, Ram; Spee, Christine; Sreekumar, Parameswaran G.; Dou, Guorui; Hinton, David R.

2014-01-01

30

Radiation-Induced Cardiomyopathy  

PubMed Central

This investigation demonstrates sequential ultrastructural lesions of cardiac myocytes in rabbits exposed locally to a single dose (1008 and 1300 rads) of x-irradiation. A wide spectrum of lesions were observed as early as 24 hours postirradiation and were followed for as long as 4 months after x-irradiation. Myofibrillar degeneration and dissociation of intercalated discs seen at 24 and 48 hours postirradiation were followed by gradual progression of myofibrillolysis and myofiber degeneration to myofiber atrophy, myofiber collapse and eventual progressive pericellular interstitial myocardial fibrosis. The possible role of dissociation of intercalated disca in the pathogenesis of well-known postirradiation electrocardiographic changes is suggested. Myofibrillar degeneration appears to be the characteristic (although non-specific) lesion of radiation having a multifactorial etiology: direct radiation effect, vascular compromise and endogenous (cardiac) catecholamine liberation. ImagesFig 1Fig 2Fig 9Fig 10Fig 11Fig 12Fig 3Fig 4Fig 5Fig 6Fig 7Fig 8 PMID:4749211

Khan, M. Yusuf

1973-01-01

31

Radiation-induced cardiovascular effects  

NASA Astrophysics Data System (ADS)

Recent epidemiological studies indicate that exposure to ionising radiation enhances the risk of cardiovascular mortality and morbidity in a moderate but significant manner. Our goal is to identify molecular mechanisms involved in the pathogenesis of radiation-induced cardiovascular disease using cellular and mouse models. Two radiation targets are studied in detail: the vascular endothelium that plays a pivotal role in the regulation of cardiac function, and the myocardium, in particular damage to the cardiac mitochondria. Ionising radiation causes immediate and persistent alterations in several biological pathways in the endothelium in a dose- and dose-rate dependent manner. High acute and cumulative doses result in rapid, non-transient remodelling of the endothelial cytoskeleton, as well as increased lipid peroxidation and protein oxidation of the heart tissue, independent of whether exposure is local or total body. Proteomic and functional changes are observed in lipid metabolism, glycolysis, mitochondrial function (respiration, ROS production etc.), oxidative stress, cellular adhesion, and cellular structure. The transcriptional regulators Akt and PPAR alpha seem to play a central role in the radiation-response of the endothelium and myocardium, respectively. We have recently started co-operation with GSI in Darmstadt to study the effect of heavy ions on the endothelium. Our research will facilitate the identification of biomarkers associated with adverse cardiac effects of ionising radiation and may lead to the development of countermeasures against radiation-induced cardiac damage.

Tapio, Soile

32

Radiation–Induced Haemorrhagic Cystitis  

Microsoft Academic Search

Objectives: In this article we review the literature concerning the frequency and management of severe haemorrhagic radiation–induced cystitis.Methods: A Medline search was performed from 1966 to 1999 for articles in English. A total of 309 references were found. Abstracts and complete articles were reviewed.Results: Severe haemorrhagic cystitis following radiotherapy remains a relatively rare event. However, the fact that it is

Jeremy P. Crew; Catherine R. Jephcott; John M. Reynard

2001-01-01

33

Analysis of rapidly synthesized guest-filled porous complexes with synchrotron radiation: practical guidelines for the crystalline sponge method.  

PubMed

A detailed set of synthetic and crystallographic guidelines for the crystalline sponge method based upon the analysis of expediently synthesized crystal sponges using third-generation synchrotron radiation are reported. The procedure for the synthesis of the zinc-based metal-organic framework used in initial crystal sponge reports has been modified to yield competent crystals in 3 days instead of 2 weeks. These crystal sponges were tested on some small molecules, with two being unexpectedly difficult cases for analysis with in-house diffractometers in regard to data quality and proper space-group determination. These issues were easily resolved by the use of synchrotron radiation using data-collection times of less than an hour. One of these guests induced a single-crystal-to-single-crystal transformation to create a larger unit cell with over 500 non-H atoms in the asymmetric unit. This led to a non-trivial refinement scenario that afforded the best Flack x absolute stereochemical determination parameter to date for these systems. The structures did not require the use of PLATON/SQUEEZE or other solvent-masking programs, and are the highest-quality crystalline sponge systems reported to date where the results are strongly supported by the data. A set of guidelines for the entire crystallographic process were developed through these studies. In particular, the refinement guidelines include strategies to refine the host framework, locate guests and determine occupancies, discussion of the proper use of geometric and anisotropic displacement parameter restraints and constraints, and whether to perform solvent squeezing/masking. The single-crystal-to-single-crystal transformation process for the crystal sponges is also discussed. The presented general guidelines will be invaluable for researchers interested in using the crystalline sponge method at in-house diffraction or synchrotron facilities, will facilitate the collection and analysis of reliable high-quality data, and will allow construction of chemically and physically sensible models for guest structural determination. PMID:25537388

Ramadhar, Timothy R; Zheng, Shao Liang; Chen, Yu Sheng; Clardy, Jon

2015-01-01

34

Analysis of rapidly synthesized guest-filled porous complexes with synchrotron radiation: practical guidelines for the crystalline sponge method  

PubMed Central

A detailed set of synthetic and crystallographic guidelines for the crystalline sponge method based upon the analysis of expediently synthesized crystal sponges using third-generation synchrotron radiation are reported. The procedure for the synthesis of the zinc-based metal–organic framework used in initial crystal sponge reports has been modified to yield competent crystals in 3 days instead of 2 weeks. These crystal sponges were tested on some small molecules, with two being unexpectedly difficult cases for analysis with in-house diffractometers in regard to data quality and proper space-group determination. These issues were easily resolved by the use of synchrotron radiation using data-collection times of less than an hour. One of these guests induced a single-crystal-to-single-crystal transformation to create a larger unit cell with over 500 non-H atoms in the asymmetric unit. This led to a non-trivial refinement scenario that afforded the best Flack x absolute stereochemical determination parameter to date for these systems. The structures did not require the use of PLATON/SQUEEZE or other solvent-masking programs, and are the highest-quality crystalline sponge systems reported to date where the results are strongly supported by the data. A set of guidelines for the entire crystallographic process were developed through these studies. In particular, the refinement guidelines include strategies to refine the host framework, locate guests and determine occupancies, discussion of the proper use of geometric and anisotropic displacement parameter restraints and constraints, and whether to perform solvent squeezing/masking. The single-crystal-to-single-crystal transformation process for the crystal sponges is also discussed. The presented general guidelines will be invaluable for researchers interested in using the crystalline sponge method at in-house diffraction or synchrotron facilities, will facilitate the collection and analysis of reliable high-quality data, and will allow construction of chemically and physically sensible models for guest structural determination. PMID:25537388

Ramadhar, Timothy R.; Zheng, Shao-Liang; Chen, Yu-Sheng; Clardy, Jon

2015-01-01

35

Flow-Induced Orientational Defects in Liquid Crystalline Polymers  

NASA Astrophysics Data System (ADS)

Liquid-crystalline polymers (LCPs) hold great potential as high-performance materials but their processing has been hampered by the difficulty of controlling molecular orientation. In particular, orientational defect lines called disclinations tend to form during molding, which disrupt molecular order and severely compromise the strength of the finished article. In this talk we describe a numerical simulation which for the first time elucidates the flow mechanism for the generation of disclinations in an LCP. The Doi theory is used to model the evolution of the LCP configuration in an eccentric cylinder geometry. The rotational flow in the wide gap causes the preferred molecular orientation, represented by the "director", to vary periodically, a phenomenon known as "director tumbling". This generates a tumbling domain whose boundary consists of a pair of half-strength disclinations. The structure of the domain is consistent with experimental observations.

Feng, Jimmy; Leal, L. Gary

1997-11-01

36

EFFECT OF LASER INDUCED CRYSTALLINITY MODIFICATION ON BIODEGRADATION PROFILE OF POLY(L-LACTIC ACID)  

E-print Network

EFFECT OF LASER INDUCED CRYSTALLINITY MODIFICATION ON BIODEGRADATION PROFILE OF POLY(L-LACTIC ACID attention due to their biocompatibility and biodegradability. Being biodegradable, poly(L-lactic acid) (PLLA it favorable in drug delivery because it hydrolyzes in the human body into lactic acid, which is then excreted

Yao, Y. Lawrence

37

Temperature induced mobility and recombination of atomic oxygen in crystalline Kr and Xe. I. Experiment  

E-print Network

Temperature induced mobility and recombination of atomic oxygen in crystalline Kr and Xe. I thermoluminescence.The recombination follows first order kinetics, from which it is inferred that atomic mobilities of activation energiesis observedin vapor depositedmatrices. I. INTRODUCTION The thermal mobility of atoms

Apkarian, V. Ara

38

Shock induced radiation from minerals  

NASA Technical Reports Server (NTRS)

Schmitt and Ahrens (1983) have concluded that the type of optical emission produced during shock compression was dependent upon phase changes taking place during shock compression. The present study is concerned with new observations of shock-induced optical radiation from Al2O3, MgO, NaCl, KCl, x-cut and fused SiO2, and LiF at various pressures up to 75 GPa. The experimental setup used in the study is similar to that employed by Schmitt and Ahrens. An Image Converter Camera with a three-frame plug-in unit was added to take two or three exposures of the radiation field during shock wave propagation through the sample, taking into account exposure times in the range from 50 to 500 nsec. The greybody emissions observed in LiF, which undergoes no phase transition, imply that localized heating and perhaps melting occurs in this material during shock deformation.

Schmitt, D.; Svendsen, B.; Ahrens, T. J.

1985-01-01

39

Hydrogeologic controls on induced seismicity in crystalline basement rocks due to fluid injection into basal reservoirs.  

PubMed

A series of Mb 3.8-5.5 induced seismic events in the midcontinent region, United States, resulted from injection of fluid either into a basal sedimentary reservoir with no underlying confining unit or directly into the underlying crystalline basement complex. The earthquakes probably occurred along faults that were likely critically stressed within the crystalline basement. These faults were located at a considerable distance (up to 10?km) from the injection wells and head increases at the hypocenters were likely relatively small (?70-150?m). We present a suite of simulations that use a simple hydrogeologic-geomechanical model to assess what hydrogeologic conditions promote or deter induced seismic events within the crystalline basement across the midcontinent. The presence of a confining unit beneath the injection reservoir horizon had the single largest effect in preventing induced seismicity within the underlying crystalline basement. For a crystalline basement having a permeability of 2?×?10(-17) ?m(2) and specific storage coefficient of 10(-7) /m, injection at a rate of 5455?m(3) /d into the basal aquifer with no underlying basal seal over 10?years resulted in probable brittle failure to depths of about 0.6?km below the injection reservoir. Including a permeable (kz ?=?10(-13) ?m(2) ) Precambrian normal fault, located 20?m from the injection well, increased the depth of the failure region below the reservoir to 3?km. For a large permeability contrast between a Precambrian thrust fault (10(-12) ?m(2) ) and the surrounding crystalline basement (10(-18) ?m(2) ), the failure region can extend laterally 10?km away from the injection well. PMID:23745958

Zhang, Yipeng; Person, Mark; Rupp, John; Ellett, Kevin; Celia, Michael A; Gable, Carl W; Bowen, Brenda; Evans, James; Bandilla, Karl; Mozley, Peter; Dewers, Thomas; Elliot, Thomas

2013-01-01

40

Proximity-induced superconductivity in crystalline Cu and Co nanowires and nanogranular Co structures  

NASA Astrophysics Data System (ADS)

We report an experimental study of proximity effect-induced superconductivity in crystalline Cu and Co nanowires and a nanogranular Co nanowire structure in contact with a superconducting W-based floating electrode (inducer). For electrical resistance measurements up to three pairs of Pt-based voltage leads were attached at different distances beside the inner inducer electrode, thus allowing us to probe the proximity effect over a length of 2-12 ?m. Up to 30% resistance drops with respect to the normal-state value have been observed for the crystalline Co and Cu nanowires when sweeping the temperature below Tc of the inducer (5.2 K). By contrast, relative R(T) drops were found to be an order of magnitude smaller for the nanogranular Co nanowire structure. Our analysis of the resistance data shows that the superconducting proximity length in crystalline Cu and Co is about 1 ?m at 2.4 K, attesting to a long-range proximity effect in the Co nanowire. Moreover, this long-range proximity effect is insusceptible to magnetic fields up to 11 T, which is indicative of spin-triplet pairing. At the same time, proximity-induced superconductivity in the nanogranular Co nanowire is strongly suppressed due to the dominating Cooper pair scattering caused by its intrinsic microstructure.

Kompaniiets, M.; Dobrovolskiy, O. V.; Neetzel, C.; Begun, E.; Porrati, F.; Ensinger, W.; Huth, M.

2014-08-01

41

Proximity-induced superconductivity in crystalline Cu and Co nanowires and nanogranular Co structures  

SciTech Connect

We report an experimental study of proximity effect-induced superconductivity in crystalline Cu and Co nanowires and a nanogranular Co nanowire structure in contact with a superconducting W-based floating electrode (inducer). For electrical resistance measurements up to three pairs of Pt-based voltage leads were attached at different distances beside the inner inducer electrode, thus allowing us to probe the proximity effect over a length of 2–12??m. Up to 30% resistance drops with respect to the normal-state value have been observed for the crystalline Co and Cu nanowires when sweeping the temperature below T{sub c} of the inducer (5.2?K). By contrast, relative R(T) drops were found to be an order of magnitude smaller for the nanogranular Co nanowire structure. Our analysis of the resistance data shows that the superconducting proximity length in crystalline Cu and Co is about 1??m at 2.4?K, attesting to a long-range proximity effect in the Co nanowire. Moreover, this long-range proximity effect is insusceptible to magnetic fields up to 11?T, which is indicative of spin-triplet pairing. At the same time, proximity-induced superconductivity in the nanogranular Co nanowire is strongly suppressed due to the dominating Cooper pair scattering caused by its intrinsic microstructure.

Kompaniiets, M., E-mail: Kompaniiets@physik.uni-frankfurt.de; Begun, E.; Porrati, F.; Huth, M. [Physikalisches Institut, Goethe University, 60438 Frankfurt am Main (Germany); Dobrovolskiy, O. V. [Physikalisches Institut, Goethe University, 60438 Frankfurt am Main (Germany); Physics Department, V. Karazin National University, 61077 Kharkiv (Ukraine); Neetzel, C.; Ensinger, W. [Department of Materials Science, TU Darmstadt, 64287 Darmstadt (Germany)

2014-08-21

42

Ultrasound visualization of internal crystalline lens deformation using laser-induced microbubbles  

NASA Astrophysics Data System (ADS)

The progressive loss of accommodation of the eye, called presbyopia, affects people with age and can result in a complete loss of accommodation by about age 55 years. It is generally accepted that presbyopia is due to an increase in stiffness of the lens. With increasing age, the stiffness of the crystalline lens nucleus increases faster than that of the cortex. During accommodation, the deformation of different parts of the crystalline lens is different and likely changes with age. However, a direct observation of crystalline lens deformation and strain distribution is difficult because although imaging methods such as OCT or Scheimpflug imaging can distinguish cortex and nucleus, they cannot determine their regional deformation. Here, patterns of laser-induced microbubbles were created in gelatin phantoms and different parts of excised animal crystalline lenses and their displacements in response to external deformation were tracked by ultrasound imaging. In the animal lenses, the deformation of the lens cortex was greater than that of nucleus and this regional difference is greater for a 27-month-old bovine lens than for a 6-month-old porcine lens. This approach enables visualization of localized, regional deformation of crystalline lenses and, if applied to lenses from animal species that undergo accommodation, may help to understand the mechanisms of accommodation and presbyopia, improve diagnostics, and, potentially, aid in the development of new methods of lens modifying presbyopia treatments.

Karpiouk, Andrei B.; Aglyamov, Salavat R.; Glasser, Adrian; Emelianov, Stanislav Y.

2014-02-01

43

Radiation-induced leukemia: lessons from history.  

PubMed

Beginning in 1895, with the discovery of x-rays, alpha and beta radiation, uranium, radium, thorium, and polonium, the fascinating story of the beginning of knowledge concerning the existence of ionizing radiation unfolds. This brief history of radiation and leukemia is divided into two main parts: the first 50 years, which deals with the confusion regarding radiation effects and the failure to clearly recognize that exposure to ionizing radiation may induce leukemia. The second part focuses on the last 60 years, when the radiation induction of leukemia was accepted and some progress achieved in understanding the clinical and pathophysiological characteristics of radiation-induced leukemia. Particular attention in this is paid to the effects of radiation on the survivors of Hiroshima and Nagasaki. The discussion in this section also covers some concepts of radiation-induced cell damage and ruminations on unanswered questions. PMID:17336261

Finch, Stuart C

2007-03-01

44

The ability of lens alpha crystallin to protect against heat-induced aggregation is age-dependent  

NASA Technical Reports Server (NTRS)

Alpha crystallin was prepared from newborn and aged bovine lenses. SDS-PAGE and tryptic peptide mapping demonstrated that both preparations contained only the alpha-A and alpha-B chains, with no significant contamination of other crystallins. Compared with alpha crystallin from the aged lens, alpha crystallin from the newborn lens was much more effective in the inhibition of beta L crystallin denaturation and precipitation induced in vitro by heat. Together, these results demonstrate that during the aging process, the alpha crystallins lose their ability to protect against protein denaturation, consistent with the hypothesis that the alpha crystallins play an important role in the maintenance of protein native structure in the intact lens.

Horwitz, J.; Emmons, T.; Takemoto, L.; Spooner, B. S. (Principal Investigator)

1992-01-01

45

Alpha-crystallin-mediated protection of lens cells against heat and oxidative stress-induced cell death.  

PubMed

In addition to their key role as structural lens proteins, ?-crystallins also appear to confer protection against many eye diseases, including cataract, retinitis pigmentosa, and macular degeneration. Exogenous recombinant ?-crystallin proteins were examined for their ability to prevent cell death induced by heat or oxidative stress in a human lens epithelial cell line (HLE-B3). Wild type ?A- or ?B-crystallin (WT-?A and WT-?B) and ?A- or ?B-crystallins, modified by the addition of a cell penetration peptide (CPP) designed to enhance the uptake of proteins into cells (gC-?B, TAT-?B, gC-?A), were produced by recombinant methods. In vitro chaperone-like assays were used to assay the ability of ?-crystallins to protect client proteins from chemical or heat induced aggregation. In vivo viability assays were performed in HLE-B3 to determine whether pre-treatment with ?-crystallins reduced death after exposure to oxidative or heat stress. Most of the five recombinant ?-crystallin proteins tested conferred some in vitro protection from protein aggregation, with the greatest effect seen with WT-?B and gC-?B. All ?-crystallins displayed significant protection to oxidative stress induced cell death, while only the ?B-crystallins reduced cell death induced by thermal stress. Our findings indicate that the addition of the gC tag enhanced the protective effect of ?B-crystallin against oxidative but not thermally-induced cell death. In conclusion, modifications that increase the uptake of ?-crystallin proteins into cells, without destroying their chaperone-like activity and anti-apoptotic functions, create the potential to use these proteins therapeutically. PMID:24275510

Christopher, Karen L; Pedler, Michelle G; Shieh, Biehuoy; Ammar, David A; Petrash, J Mark; Mueller, Niklaus H

2014-02-01

46

Possibility of Radiation-Induced Degradation of Concrete by Alkali-Silica Reaction of Aggregates  

Microsoft Academic Search

The effect of Ar ion irradiation on the reactivity of crystalline and amorphous quartz to alkali has been examined for clarifying whether radiation from nuclear reactors accelerates the degradation of concrete by inducing alkali-silica reaction of aggregates. Distorted amorphous quartz generated on the surface of quartz by irradiation of a 200 keV Ar ion beam is at least 700 times

Tsuneki ICHIKAWA; Hitoshi KOIZUMI

2002-01-01

47

SDS induced structural changes in alpha-crystallin and it's effect on refolding.  

PubMed

Alpha-crystallin, a major eye lens protein and a key member of the small heat shock protein family, acts like a chaperone by preventing aggregation of substrate proteins. One of the hallmarks of most small heat shock proteins is their existence as a large oligomer, the role of which in its function is not understood at present. We have studied the role of the oligomer in the stability of its structure against SDS induced destabilization by CD measurements. Alpha-crystallin from bovine source as well as recombinant preparation was used for this purpose. As SDS concentration was gradually increased, the beta-sheet structure was diminished followed by concomitant increase in the alpha-helical structure. The quaternary structural changes in presence of SDS were also monitored by light scattering, polarization and anisotropy measurements. It was found that the breakdown of the oligomeric structure was nearly complete above 1 mM SDS concentration. The results were compared with that of a monomeric gamma-crystallin, which is also a major beta-sheet protein like alpha-crystallin. When alpha-crystallin was first converted into monomeric random coil structure in presence of 6 M urea and allowed to refold in SDS solution, amount of alpha-helix was more than that incubated directly in the same concentration of SDS. The results show that alpha-crystallin attains extra structural stability against external stress due to its oligomeric structure. The implication for the extra stability is discussed in reference to its function as molecular chaperone. PMID:15648975

Biswas, Ashis; Das, Kali P

2004-11-01

48

Milling induces disorder in crystalline griseofulvin and order in its amorphous counterpart  

SciTech Connect

This study investigates two apparently similar thermal signatures, shaped as bimodal exotherms, observed when either the crystalline or the amorphous from of the drug are subjected to milling. Crystalline griseofulvin was cryomilled and the (quenched-melt) amorphous form was subjected to either cryomilling or grinding. The thermal and surface properties of the resulting samples were analyzed using differential scanning calorimetry (DSC) and surface energy analysis. After milling, both the crystalline and the amorphous material revealed visually similar bimodal exothermic events when the heating rate was 20 C min{sup -1}. Under different heating rates, the pair of DSC peaks for the bimodal exotherm of each material behaved entirely different from each other. The two peaks of the bimodal event, as well as the glass transition, can be kinetically resolved for the ground amorphous form using standard mode DSC. In contrast, similar analysis was unable to resolve the bimodal exotherm or a glass transition in the case of the cryomilled crystals. Furthermore, cryomilled crystals do not exhibit a glass transition even when analyzed using modulated DSC. Synchrotron sourced X-ray analysis revealed that grinding the amorphous material results in the nucleation and growth of the crystalline form. Milling thus induces disorder in the crystals of griseofulvin but induces order in the amorphous form of the drug. The surface of the two milled systems consistently exhibited different energetics under a wide range of relative humidity conditions. These findings suggest that cryomilling induces both bulk and surface disorder, specifically, a certain level of dislocations on the crystal. In contrast, grinding the amorphous material lowers the activation energy for crystal formation, inducing nuclei formation and growth throughout the amorphous matrix.

Otte, Andrew; Zhang, Yan; Carvajal, M. Teresa; Pinal, Rodolfo (Purdue)

2012-04-02

49

Medium-induced multi-photon radiation  

E-print Network

We study the spectrum of multi-photon radiation off a fast quark in medium in the BDMPS/ASW approach. We reproduce the medium-induced one-photon radiation spectrum in dipole approximation, and go on to calculate the two-photon radiation in the Moli\\`{e}re limit. We find that in this limit the LPM effect holds for medium-induced two-photon ladder emission.

Hao Ma; Carlos A. Salgado; Konrad Tywoniuk

2011-05-29

50

Modeling radiation-induced cell cycle delays  

Microsoft Academic Search

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

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

2009-01-01

51

Temperature dependence of the radiative recombination coefficient in crystalline silicon from spectral photoluminescence  

SciTech Connect

The radiative recombination coefficient B(T) in crystalline silicon is determined for the temperature range 90–363?K, and in particular from 270 to 350?K with an interval of 10?K, where only sparse data are available at present. The band-band absorption coefficient established recently by Nguyen et al. [J. Appl. Phys. 115, 043710 (2014)] via photoluminescence spectrum measurements is employed to compute the values of B(T) at various temperatures. The results agree very well with literature data from Trupke et al. [J. Appl. Phys. 94, 4930 (2003).] We present a polynomial parameterization describing the temperature dependence of the product of B(T) and the square of the intrinsic carrier density. We also find that B(T) saturates at a near constant value at room temperature and above for silicon samples with relatively low free carrier densities.

Nguyen, Hieu T., E-mail: hieu.nguyen@anu.edu.au; Macdonald, Daniel [Research School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, ACT 0200 (Australia); Baker-Finch, Simeon C. [Research School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra, ACT 0200 (Australia); PV Lighthouse, Coledale, NSW 2515 (Australia)

2014-03-17

52

Radiation-induced gene responses  

SciTech Connect

In the process of identifying genes that are differentially regulated in cells exposed to ultraviolet radiation (UV), we identified a transcript that was repressed following the exposure of cells to a combination of UV and salicylate, a known inhibitor of NF-kappaB. Sequencing this band determined that it has identify to lactate dehydrogenase, and Northern blots confirmed the initial expression pattern. Analysis of the sequence of the LDH 5` region established the presence of NF-kappaB, Sp1, and two Ap-2 elements; two partial AP- 1; one partial RE, and two halves of E-UV elements were also found. Electromobility shift assays were then performed for the AP-1, NF- kappaB, and E-UV elements. These experiments revealed that binding to NF-kappaB was induced by UV but repressed with salicylic acid; UV did not affect AP-1 binding, but salicylic acid inhibited it alone or following UV exposure; and E-UV binding was repressed by UV, and salicylic acid had little effect. Since the binding of no single element correlated with the expression pattern of LDH, it is likely that multiple elements govern UV/salicylate-mediated expression.

Woloschak, G.E.; Paunesku, T.; Shearin-Jones, P.; Oryhon, J.

1996-12-31

53

The C-terminal region of alpha-crystallin: involvement in protection against heat-induced denaturation  

NASA Technical Reports Server (NTRS)

Recent studies have demonstrated that the alpha-crystallins can protect other proteins against heat-induced denaturation and aggregation. To determine the possible involvement of the C-terminal region in this activity, the alpha-crystallins were subjected to limited tryptic digestion, and the amount of cleavage from the N-terminal and C-terminal regions of the alpha-A and alpha-B crystallin chains was assessed using antisera specific for these regions. Limited tryptic digestion resulted in cleavage only from the C-terminal region of alpha-A crystallin. This trypsin-treated alpha-A crystallin preparation showed a decreased ability to protect proteins from heat-induced aggregation using an in vitro assay. Together, these results demonstrate that the C-terminal region of alpha-A crystallin is important for its ability to protect against heat-induced aggregation, which is consistent with the hypothesis that post-translational changes that are known to occur at the C-terminal region may have significant effects on the ability of alpha-A crystallin to protect against protein denaturation in vivo.

Takemoto, L.; Emmons, T.; Horwitz, J.; Spooner, B. S. (Principal Investigator)

1993-01-01

54

Micromechanical Modeling of Anisotropic Damage-Induced Permeability Variation in Crystalline Rocks  

NASA Astrophysics Data System (ADS)

This paper presents a study on the initiation and progress of anisotropic damage and its impact on the permeability variation of crystalline rocks of low porosity. This work was based on an existing micromechanical model considering the frictional sliding and dilatancy behaviors of microcracks and the recovery of degraded stiffness when the microcracks are closed. By virtue of an analytical ellipsoidal inclusion solution, lower bound estimates were formulated through a rigorous homogenization procedure for the damage-induced effective permeability of the microcracks-matrix system, and their predictive limitations were discussed with superconducting penny-shaped microcracks, in which the greatest lower bounds were obtained for each homogenization scheme. On this basis, an empirical upper bound estimation model was suggested to account for the influences of anisotropic damage growth, connectivity, frictional sliding, dilatancy, and normal stiffness recovery of closed microcracks, as well as tensile stress-induced microcrack opening on the permeability variation, with a small number of material parameters. The developed model was calibrated and validated by a series of existing laboratory triaxial compression tests with permeability measurements on crystalline rocks, and applied for characterizing the excavation-induced damage zone and permeability variation in the surrounding granitic rock of the TSX tunnel at the Atomic Energy of Canada Limited's (AECL) Underground Research Laboratory (URL) in Canada, with an acceptable agreement between the predicted and measured data.

Chen, Yifeng; Hu, Shaohua; Zhou, Chuangbing; Jing, Lanru

2014-09-01

55

Radiation-induced sarcoma of the thyroid  

SciTech Connect

A 23-year-old white man presented with a thyroid mass 12 years after receiving high-dose radiotherapy for a T2 and N1 lymphoepithelioma of the nasopharynx. Following subtotal thyroidectomy, a histopathologic examination revealed liposarcoma of the thyroid gland. The relationship between sarcomas and irradiation is described and Cahan and colleagues' criteria for radiation-induced sarcomas are reviewed. To our knowledge, we are presenting the first such case of a radiation-induced sarcoma of the thyroid gland.

Griem, K.L.; Robb, P.K.; Caldarelli, D.D.; Templeton, A.C. (Rush-Presbyterian-St Luke's Medical Center, Chicago, IL (USA))

1989-08-01

56

Carnosine inhibits modifications and decreased molecular chaperone activity of lens ? ? ? ? ?-crystallin induced by ribose and fructose 6-phosphate  

Microsoft Academic Search

Purpose: ?-Crystallin, a major structural protein in the lens, prevents heat- and oxidative stress-induced aggregation of proteins and inactivation of enzymes by acting as a molecular chaperone. Modification of ?-crystallin by some posttrans- lational modifications results in conformational changes and decreases in chaperone activity, which may contribute to cataractogenesis in vivo. Carnosine (?-alanyl-L-histidine), an endogenous histidine dipeptide, prevents protein modifica-

Hong Yan; John J. Harding

2006-01-01

57

Radiation effects and annealing kinetics in crystalline silicates, phosphates and complex Nb-Ta-Ti oxides. FInal Report  

SciTech Connect

Interaction of heavy particles (alpha-recoil nuclei, fission fragments, implanted ions) with ceramics is complex because they have a wide range of structure types, complex compositions and chemical bonding is variable. Radiation damage can produce diverse results, but most commonly, crystalline periodic materials become either polycrystalline or aperiodic (metamict state). We studied the transition from crystalline to aperiodic state in natural materials that have been damaged by alpha recoil nuclei in the U and Th decay series and in synthetic, analogous structure types which have been amorphized by ion implantation. Transition from crystalline to aperiodic was followed by analysis of XRD, high resolution TEM, and EXAFS/XANE spectroscopy. Use of these techniques with increasing dose provided data on an increasing finer scale as the damage process progressed.

Ewing, R.C.

1987-08-10

58

Radiation-induced craniofacial bone growth disturbances.  

PubMed

Multimodality treatment, including radiotherapy, chemotherapy, and surgery, is required for the management of head and neck cancer in pediatric patients. Despite the modern advances in radiation dosing and targeting techniques, the radiation damage to the growing craniofacial skeleton in children remains a significant clinical problem. The first part of this review summarizes the clinical effects of radiotherapy on craniofacial bone growth in children. Experimental evidence on therapeutic radiation effects on bone growth in in vivo and in vitro models is reviewed. The second part of this review focuses on prevention of radiation-induced craniofacial bone growth inhibition using radioprotective agents. PMID:17912072

Gevorgyan, Artur; La Scala, Giorgio C; Neligan, Peter C; Pang, Cho Y; Forrest, Christopher R

2007-09-01

59

[Like anticataract agents, the antiaggregants of lens crystallin. Communication 2. Study of the impact of chaperon-like (protective) activity of short-chain peptides on the rate of UV-induced aggregation of betaL-crystallins by eximer laser].  

PubMed

UV-induced aggregation of betaL-crystallin, one of the major lens proteins, was studied under its pulse radiation with XeCl laser at a wavelength of 308 nm. Unlike the in vitro tested dipeptides L-carnosine, N-acetyl carnosine, D-panthetine, and particularly their combination, the so-called new chaperon was demonstrated to slow down the rate of photoaggregatin of beta-crystallin. The new chaperon, a mixture of D-pathethine and N-acetyl carnosine was ascertained to protect a mixture of betaL- and alpha-crystallins from UV-induced aggregation to a greater extent than D-pathethine or N-acetyl carnosine used alone. An effective drug based on the new chaperon may be designed for the prevention of cataract in sight. PMID:18488460

Soustov, L V; Chelnokov, E V; Sapogova, N V; Bitiurin, N M; Nemov, V V; Karpova, O E; Sheremet, N L; Polunin, G S; Avetisov, S E; Ostrovski?, M A

2008-01-01

60

Mesoscale modeling of strain induced solid state amorphization in crystalline materials  

NASA Astrophysics Data System (ADS)

Solid state amorphization, and in particular crystalline to amorphous transformation, can be observed in metallic alloys, semiconductors, intermetallics, minerals, and also molecular crystals when they undergo irradiation, hydrogen gas dissolution, thermal interdiffusion, mechanical alloying, or mechanical milling. Although the amorphization mechanisms may be different, the transformation occurs due to the high level of disorder introduced into the material. Milling induced solid state amorphization is proposed to be the result of accumulation of crystal defects, specifically dislocations, as the material is subjected to large deformations during the high energy process. Thus, understanding the deformation mechanisms of crystalline materials will be the first step in studying solid state amorphization in crystalline materials, which not only has scientific contributions, but also technical consequences. A phase field dislocation dynamics (PFDD) approach is employed in this work to simulate plastic deformation of molecular crystals. This PFDD model has the advantage of tracking all of the dislocations in a material simultaneously. The model takes into account the elastic interaction between dislocations, the lattice resistance to dislocation motion, and the elastic interaction of dislocations with an external stress field. The PFDD model is employed to describe the deformation of molecular crystals with pharmaceutical applications, namely, single crystal sucrose, acetaminophen, gamma-indomethacin, and aspirin. Stress-strain curves are produced that result in expected anisotropic material response due to the activation of different slip systems and yield stresses that agree well with those from experiments. The PFDD model is coupled to a phase transformation model to study the relation between plastic deformation and the solid state amorphization of crystals that undergo milling. This model predicts the amorphous volume fraction in excellent agreement with experimental observation. Finally, we incorporate the effect of stress free surfaces to model the behavior of dislocations close to these surfaces and in the presence of voids.

Lei, Lei

61

[Theoretical model of radiation-induced cancer].  

PubMed

A model of the dose dependence of the incidence of radiation-induced malignant tumors is proposed to provide a reliable estimation of the carcinogenic risk from low-level radiation. The model describes three main routs (cellular, tissue and system ones) by which radiation influences carcinogenesis. In terms of the two-stage theory of carcinogenesis, the first route deals with the initiating effect of radiation, and the second and third routs, with its promotion action. The proposed model gives a satisfactory combined description of the leukaemogenic effect of gamma-rays and neutrons. A theoretical explanation is presented of the differences in the pattern of the dose dependences of the yield of similar forms of the induced cancer exhibited by radiosensitive and radioresistant animal strains. PMID:6473724

Petoian, I M; Filiushkin, I V

1984-01-01

62

Imaging Radiation-Induced Normal Tissue Injury  

PubMed Central

Technological developments in radiation therapy and other cancer therapies have led to a progressive increase in five-year survival rates over the last few decades. Although acute effects have been largely minimized by both technical advances and medical interventions, late effects remain a concern. Indeed, the need to identify those individuals who will develop radiation-induced late effects, and to develop interventions to prevent or ameliorate these late effects is a critical area of radiobiology research. In the last two decades, preclinical studies have clearly established that late radiation injury can be prevented/ameliorated by pharmacological therapies aimed at modulating the cascade of events leading to the clinical expression of radiation-induced late effects. These insights have been accompanied by significant technological advances in imaging that are moving radiation oncology and normal tissue radiobiology from disciplines driven by anatomy and macrostructure to ones in which important quantitative functional, microstructural, and metabolic data can be noninvasively and serially determined. In the current article, we review use of positron emission tomography (PET), single photon emission tomography (SPECT), magnetic resonance (MR) imaging and MR spectroscopy to generate pathophysiological and functional data in the central nervous system, lung, and heart that offer the promise of, (1) identifying individuals who are at risk of developing radiation-induced late effects, and (2) monitoring the efficacy of interventions to prevent/ameliorate them. PMID:22348250

Robbins, Mike E.; Brunso-Bechtold, Judy K.; Peiffer, Ann M.; Tsien, Christina I.; Bailey, Janet E.; Marks, Lawrence B.

2013-01-01

63

Radiation induced conductivity in space dielectric materials  

SciTech Connect

The radiation-induced conductivity of some polymers was described mainly in literature by a competition between ionization, trapping/detrapping, and recombination processes or by radiation assisted ageing mechanisms. Our aim is to revise the effect of the aforementioned mechanisms on the complex evolution of Teflon{sup ®} FEP under space representative ionizing radiation. Through the definition of a new experimental protocol, revealing the effect of radiation dose and relaxation time, we have been able to demonstrate that the trapping/recombination model devised in this study agrees correctly with the observed experimental phenomenology at qualitative level and allows describing very well the evolution of radiation induced conductivity with irradiation time (or received radiation dose). According to this model, the complex behavior observed on Teflon{sup ®} FEP may be basically ascribed to the competition between electron/hole pairs generation and recombination: electrons are deeply trapped and act as recombination centers for free holes. Relaxation effects have been characterized through successive irradiations steps and have been again well described with the defined model at qualitative level: recombination centers created by the irradiation induce long term alteration on the electric properties, especially the effective bulk conductivity. One-month relaxation does not allow a complete recovery of the material initial charging behavior.

Hanna, R. [DESP, The French Aerospace Lab, 2 avenue Edouard Belin, 31055 Toulouse (France); Energie, SUPELEC, 3 rue Joliot Curie, 91192 Gif sur Yvette (France); CNES, 18 avenue Edouard Belin, 31401 Toulouse (France); Paulmier, T., E-mail: thierry.paulmier@onera.fr; Belhaj, M.; Dirassen, B. [DESP, The French Aerospace Lab, 2 avenue Edouard Belin, 31055 Toulouse (France); Molinie, P. [Energie, SUPELEC, 3 rue Joliot Curie, 91192 Gif sur Yvette (France); Payan, D.; Balcon, N. [CNES, 18 avenue Edouard Belin, 31401 Toulouse (France)

2014-01-21

64

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon  

NASA Astrophysics Data System (ADS)

The pressure- and indentation-induced phase transformations in crystalline (cd) and amorphous (a) silicon are studied by using molecular dynamics simulations based on the modified Tersoff potential. The sp3s? tight-binding scheme is employed to gain insight into the origin of the change in conductivity during nanoindentation. The Gibbs free energy calculations predict the following pressure-induced phase transitions: cd-Si??-tin Si(?-Si) (11.4 GPa); cd-Si?high density amorphous phase (HDA) (22.5 GPa); a-Si??-Si (2.5 GPa); a-Si?HDA (8.4 GPa). Simulations of nanoindentation of crystalline silicon reveal discontinuities in the load-displacement curves. In the loading curves of the cd-Si (100) substrate, the pop-in is assigned to the appearance of the ?-tin Si phase. During unloading, the pop-out is due to the formation of a low-density amorphous phase a-Si . The a-Si?HDA transformation takes place during nanoindentation of a-Si in loading regime. Upon unloading the a-Si phase is preserved. The structural transformations in cd-Si and a-Si during nanoindentation are treated in terms of triaxial and uniaxial compressions of the respective bulk samples. A change in conductivity from semiconducting to metallic during nanoindentation of the cd-Si (100) and a-Si slabs is explained in terms of a transformation of the localized electronic states in the band gap region. The results are compared to those of available theoretical models and experiments.

Ivashchenko, V. I.; Turchi, P. E. A.; Shevchenko, V. I.

2008-07-01

65

On the Pressure-Induced Loss of Crystallinity in Zinc- and Calcium-Phosphates  

SciTech Connect

A recently suggested mechanism for the stress memory of various metal phosphates is investigated experimentally. Based on first-principles simulations [N. J. Mosey et al., Science 307, 1612 (2005)], it had been argued that atoms with flexible coordination, such as zinc or heavy-metal cations, act as network-forming agents, undergoing irreversible pressure-induced changes in bonding that lead to increased connectivity between phosphate anions. In the present study, orthophosphates of zinc and calcium were exposed to high pressures on surfaces and in diamond anvil cells. An additional set of first-principles simulations was accomplished on ?-orthophosphate of zinc, which suggested that this material was already cross-linked before compression but that it nevertheless underwent a reversible coordination change under pressure in agreement with the experimental results presented here. Raman spectra indicate an irreversible, pressure-induced loss of long-range crystallinity. The pressures required to induce these changes are around 7 GPa for the zinc phosphates, while they are close to 21 GPa for the calcium phosphates. Hydrogenation of the metal phosphate lowers the threshold pressure by approximately 2-3 GPa in both cases. Moreover, ?-orthophosphate of zinc could be partially amorphisized under nonisotropic pressure on copper foils.

Shakhvorostov, D.; Mosey, N; Munoz-Paniagua, D; Pereira, G; Song, Y; Kasrai, M; Norton, P; Müser, M

2008-01-01

66

Radiation-Induced Phase Transformations in Ilmenite-Group Minerals  

SciTech Connect

Transmission electron microscopy (TEM) is a powerful tool for characterizing and understanding radiation-induced structural changes in materials. We have irradiated single crystals of ilmenite (FeTiO{sub 3}) and geikielite (MgTiO{sub 3}) using ions and electrons to better understand the response of complex oxides to radiation. Ion irradiation experiments of bulk single crystals at 100 K show that ilmenite amorphized at doses of less than 1x10(exp15) Ar(2+)/sq cm and at a damage level in the peak damage region of 1 displacement per atom (dpa). Transmission electron microscopy and electron diffraction of a cross-sectioned portion of this crystal confirmed the formation of a 150 am thick amorphous layer. Geikielite proved to be more radiation resistant, requiring a flux of 2x10(exp 15) Xe(2+)/sq cm to induce amorphization at 100 K. This material did not amorphize at 470 K, despite a dose of 2.5 x10(exp 16) Xe(2+)/sq cm and a damage level as high as 25 dpa. Low temperature irradiations of electron- transparent crystals with 1 MeV Kr(+) also show that ilmenite amorphized after a damage level of 2.25 dpa at 175 K.Similar experiments on geikielite show that the microstructure is partially amorphous and partially crystalline after 10 dpa at 150 K. Concurrent ion and electron irradiation of both materials with 1 MeV Kr(+) and 0.9 MeV electrons produced dislocation loops in both materials, but no amorphous regions were formed. Differences in the radiation response of these isostructural oxides suggests that in systems with Mg-Fe solid solution, the Mg-rich compositions may be more resistant to structural changes.

Mitchell, J. N.

1997-12-31

67

Quercetin Inhibits Radiation-Induced Skin Fibrosis  

PubMed Central

Radiation induced fibrosis of the skin is a late toxicity that may result in loss of function due to reduced range of motion and pain. The current study sought to determine if oral delivery of quercetin mitigates radiation-induced cutaneous injury. Female C3H/HeN mice were fed control chow or quercetin-formulated chow (1% by weight). The right hind leg was exposed to 35 Gy of X rays and the mice were followed serially to assess acute toxicity and hind leg extension. Tissue samples were collected for assessment of soluble collagen and tissue cytokines. Human and murine fibroblasts were subjected to clonogenic assays to determine the effects of quercetin on radiation response. Contractility of fibroblasts was assessed with a collagen contraction assay in the presence or absence of quercetin and transforming growth factor-? (TGF-?). Western blotting of proteins involved in fibroblast contractility and TGF-? signaling were performed. Quercetin treatment significantly reduced hind limb contracture, collagen accumulation and expression of TGF-? in irradiated skin. Quercetin had no effect on the radioresponse of fibroblasts or murine tumors, but was capable of reducing the contractility of fibroblasts in response to TGF-?, an effect that correlated with partial stabilization of phosphorylated cofilin. Quercetin is capable of mitigating radiation induced skin fibrosis and should be further explored as a therapy for radiation fibrosis. PMID:23819596

Horton, Jason A.; Li, Fei; Chung, Eun Joo; Hudak, Kathryn; White, Ayla; Krausz, Kristopher; Gonzalez, Frank; Citrin, Deborah

2013-01-01

68

Radiation-induced mutations and plant breeding  

SciTech Connect

Ionizing radiation could cause genetic changes in an organism and could modify gene linkages. The induction of mutation through radiation is random and the probability of getting the desired genetic change is low but can be increased by manipulating different parameters such as dose rate, physical conditions under which the material has been irradiated, etc. Induced mutations have been used as a supplement to conventional plant breeding, particularly for creating genetic variability for specific characters such as improved plant structure, pest and disease resistance, and desired changes in maturity period; more than 200 varieties of crop plants have been developed by this technique. The Pakistan Atomic Energy Commission has used this technique fruitfully to evolve better germplasm in cotton, rice, chickpea, wheat and mungbean; some of the mutants have become popular commercial varieties. This paper describes some uses of radiation induced mutations and the results achieved in Pakistan so far.

Naqvi, S.H.M.

1985-01-01

69

Radiation-induced meningiomas in pediatric patients  

SciTech Connect

Radiation-induced meningiomas rarely have latency periods short enough from the time of irradiation to the clinical presentation of the tumor to present in the pediatric patient. Three cases of radiation-induced intracranial meningiomas in pediatric patients are presented. The first involved a meningioma of the right frontal region in a 10-year-old boy 6 years after the resection and irradiation of a 4th ventricular medulloblastoma. Review of our pediatric tumor cases produced a second case of a left temporal fossa meningioma presenting in a 15-year-old boy with a history of irradiation for retinoblastoma at age 3 years and a third case of a right frontoparietal meningioma in a 15-year-old girl after irradiation for acute lymphoblastic leukemia. Only three cases of meningiomas presenting in the pediatric age group after radiation therapy to the head were detected in our review of the literature.

Moss, S.D.; Rockswold, G.L.; Chou, S.N.; Yock, D.; Berger, M.S.

1988-04-01

70

CRYSTALLINE-TO-AMORPHOUS TRANSFORMATION OF INTERMETALLIC COMPOUNDS IN THE ZR-FE-M SYSTEM INDUCED BY IRRADIATION  

E-print Network

CRYSTALLINE-TO-AMORPHOUS TRANSFORMATION OF INTERMETALLIC COMPOUNDS IN THE ZR-FE-M SYSTEM INDUCED, the damage accumulation mechanisms in the intermetallic compound, and the annealing mechanisms available, Argonne National Laboratory, Argonne, IL 60439, USA. ABSTRACT The binary and ternary intermetallic

Motta, Arthur T.

71

Cataracts induced by microwave and ionizing radiation  

SciTech Connect

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

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

1988-11-01

72

Radiation-induced brain injury: A review  

PubMed Central

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 integration at clinically relevant doses and schedules. Recently developed techniques in neuroscience and neuroimaging provide not only an opportunity to accomplish this, but they also offer the opportunity to identify new biomarkers and new targets for interventions to prevent or ameliorate these late effects. PMID:22833841

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

2012-01-01

73

Delayed Radiation-Induced Vasculitic Leukoencephalopathy  

SciTech Connect

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.

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

74

Ultrafast sub-threshold photo-induced response in crystalline and amorphous GeSbTe thin films  

NASA Astrophysics Data System (ADS)

Pump-probe optical reflectivity and terahertz transmission measurements have been used to investigate time resolved sub-threshold photo-induced effects in crystalline and amorphous GeSbTe films at MHz repetition rates. The reflectivity in both phases exhibits long-lived modulations consistent with the sign of the changes that occur upon switching but of smaller magnitude. These can be understood by the generation of acoustic strains with the crystalline phase response dominated by thermal effects and the amorphous phase response associated with electronically induced changes. Evidence for a photo-induced distortion is observed in the amorphous phase which develops homogeneously within the excited region on few-picosecond time scales.

Shu, M. J.; Chatzakis, I.; Kuo, Y.; Zalden, P.; Lindenberg, A. M.

2013-05-01

75

Radiation-induced neurological complications of nasopharyngeal carcinoma Radiation-induced neurological complications of nasopharyngeal carcinoma Radiation-induced neurological complications of nasopharyngeal carcinoma Radiation-induced neurological complications of nasopharyngeal carcinoma Radiation-induced neurological complications of nasopharyngeal carcinoma  

Microsoft Academic Search

Objectives: To review radiation-induced neurological complications of nasopharyngeal carcinoma (NPC). Materials & Methods: Retrospective review of patients with radiation-induced neurological complications of NPC who presented to the Neurology and Neurosurgery Departments, Tan Tock Seng Hospital in the five-year period from 1994 to 99. Results: Nine patients with 10 neurological complications were seen. Four patients had cranial nerve palsies, of whom

LCS Tan; YY Sitoh; HTL Tjia

1999-01-01

76

Radiation-induced mutation at minisatellite loci  

SciTech Connect

We are studying the radiation-induced increase of mutation rate in minisatellite loci in mice and humans. Minisatellite mutations were scored by multilocus DNA fingerprint analysis in the progeny of {gamma}-irradiated and non-irradiated mice. The frequency of mutation in offspring of irradiated males was 1.7 higher that in the control group. Germline mutation at human minisatellite loci was studied among children born in heavily polluted areas of the Mogilev district of Belarus after the Chernobyl accident and in a control population. The frequency of mutation assayed both by DNA fingerprinting and by eight single locus probes was found to be two times higher in the exposed families than in the control group. Furthermore, mutation rate was correlated with the parental radiation dose for chronic exposure {sup 137}Cs, consistent with radiation-induction of germline mutation. The potential use of minisatellites in monitoring germline mutation in humans will be discussed.

Dubrova, Y.E. [Univ. of Leicester (United Kingdom)]|[Vavilov Institute of General Genetics, Moscow (Russian Federation); Nesterov, V.N.; Krouchinsky, N.G. [Research Institute for Radiation Medicine, Mogilev (Belarus)] [and others

1997-10-01

77

Heat pump processes induced by laser radiation  

NASA Technical Reports Server (NTRS)

A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

Garbuny, M.; Henningsen, T.

1980-01-01

78

Radiation induced fracture of the scapula  

SciTech Connect

A case of radiation induced osteonecrosis resulting in a fracture of the scapula in a 76-yr-old female patient with a history of breast carcinoma is presented. Diagnostic imaging, laboratory recommendations and clinical findings are discussed along with an algorithm for the safe management of patients with a history of cancer and musculoskeletal complaints. This case demonstrates the necessity of a thorough investigation of musculoskeletal complaints in patients with previous bone-seeking carcinomas.

Riggs, J.H. III; Schultz, G.D.; Hanes, S.A. (Los Angeles College of Chiropractic, Whittier, CA (USA))

1990-10-01

79

Radiation induced transformation of CO in cyclohexane  

NASA Astrophysics Data System (ADS)

The radiation induced incorporation of CO in cyclohexane leads to formation of: bicyclohexylketone ( Gi = 2.40), ?, ?-bicyclohexyldiketone ( Gi = 0.90), cyclohexanone ( Gi = 0.24), cyclohexanol ( Gi = 0.20), cyclohexanecarboxylic acid ( Gi = 0.10), in addition to bicyclohexyl ( Gi = 1.30) and polymers. The G i-values are strongly dependent on the CO-concentration in the solution. Probable reaction mechanisms are presented.

Lugovoi, Y. M.; Park, H.-R.; Getoff, N.

80

Radiation-induced morphea - a literature review.  

PubMed

Radiation-induced morphea (RIM) is a rare and under-recognized skin complication of radiotherapy. It is commonly wrongly diagnosed as other dermatological conditions or malignancy because of similar clinical characteristics. This literature review analyses 66 cases that have been reported in the literature since 1989. The clinical appearance often includes pain and disfiguration of affected area, which may influence the patient's quality of life. There is no clear connection between the radiotherapy dose, the fractionation scheme, the use of a boost, age, the presence of other dermatological conditions or other connective tissue diseases and the occurrence of RIM. Its pathogenesis is still unclear, but several theories are proposed to explain this phenomenon. The available data suggest that the abnormally high secretion of some cytokines (interleukin 4, interleukin 5, transforming growth factor) induced by radiation causes an extensive fibrosis after an activation of fibroblasts. Histological confirmation is crucial in distinguishing RIM from similar-looking diseases, such as chronic radiation dermatitis, cancer recurrence, radiation, recall dermatitis, new carcinoma or cellulitis. There is no clear treatment regimen for this condition. Clinical outcome after therapy is often unsatisfactory. The commonly used methods and agents include: topical and systemic steroids, calcineurin inhibitors, systemic immunosuppressants including methotrexate, tacrolimus, heparin, hyaluronidase, phototherapy (UVA, UVA1, UVB, PUVA), systemic antibiotics, imiquimod, mycophenolate mofetil, photophoresis. The differential diagnosis is challenging and requires a multidisciplinary approach to avoid misdiagnosis and to plan appropriate treatment. PMID:25174551

Spalek, M; Jonska-Gmyrek, J; Ga?ecki, J

2015-02-01

81

Crystal Field Effect Induced Topological Crystalline Insulators In Monolayer IV-VI Semiconductors.  

PubMed

Two-dimensional (2D) topological crystalline insulators (TCIs) were recently predicted in thin films of the SnTe class of IV-VI semiconductors, which can host metallic edge states protected by mirror symmetry. As thickness decreases, quantum confinement effect will increase and surpass the inverted gap below a critical thickness, turning TCIs into normal insulators. Surprisingly, based on first-principles calculations, here we demonstrate that (001) monolayers of rocksalt IV-VI semiconductors XY (X = Ge, Sn, Pb and Y = S, Se, Te) are 2D TCIs with the fundamental band gap as large as 260 meV in monolayer PbTe. This unexpected nontrivial topological phase stems from the strong crystal field effect in the monolayer, which lifts the degeneracy between px,y and pz orbitals and leads to band inversion between cation pz and anion px,y orbitals. This crystal field effect induced topological phase offers a new strategy to find and design other atomically thin 2D topological materials. PMID:25741907

Liu, Junwei; Qian, Xiaofeng; Fu, Liang

2015-04-01

82

?B-crystallin reduces ristocetin?induced soluble CD40 ligand release in human platelets: Suppression of thromboxane A2 generation.  

PubMed

Our group has previously shown that ?B?crystallin (HSPB5), a small heat shock protein, inhibits human platelet aggregation by ristocetin, an activator of glycoprotein Ib/IX/V. In addition, it was demonstrated that glycoprotein Ib/IX/V activation induces soluble CD40 (sCD40) ligand release via thromboxane (TX) A2. In the present study, the effect of ?B?crystallin on the ristocetin?induced sCD40 ligand release in human platelets was investigated. The ristocetin?induced release of sCD40 ligand was suppressed by ?B?crystallin. In addition, ?B?crystallin reduced the ristocetin?stimulated production of 11?dehydro?TX B2, a stable metabolite of TXA2. ?B?crystallin did not suppress the platelet aggregation induced by U46619, a TXA2 receptor agonist. ?B?crystallin had little effect on the U46619?induced phosphorylation of p38 mitogen?activated protein kinase or sCD40 ligand release. In addition, ?B?crystallin failed to reduce the binding of SZ2, a monoclonal antibody against the sulfated sequence in the ??chain of glycoprotein Ib, to the ristocetin?stimulated platelets. These results strongly suggest that ?B?crystallin extracellularly suppresses ristocetin?stimulated release of sCD40 ligand by inhibiting the TXA2 production in human platelets. PMID:25760062

Tsujimoto, Masanori; Doi, Tomoaki; Kuroyanagi, Gen; Yamamoto, Naohiro; Matsushima-Nishiwaki, Rie; Iida, Yuko; Enomoto, Yukiko; Iida, Hiroki; Ogura, Shinji; Otsuka, Takanobu; Tokuda, Haruhiko; Kozawa, Osamu; Iwama, Toru

2015-07-01

83

Selenomethionine protects against adverse biological effects induced by space radiation  

Microsoft Academic Search

Ionizing radiation-induced adverse biological effects impose serious challenges to astronauts during extended space travel. Of particular concern is the radiation from highly energetic, heavy, charged particles known as HZE particles. The objective of the present study was to characterize HZE particle radiation-induced adverse biological effects and evaluate the effect of d-selenomethionine (SeM) on the HZE particle radiation-induced adverse biological effects.

Ann R. Kennedy; Jeffrey H. Ware; Jun Guan; Jeremiah J. Donahue; John E. Biaglow; Zhaozong Zhou; Jelena Stewart; Marcelo Vazquez; X. Steven Wan

2004-01-01

84

Cathodoluminescence of radiation-induced zircon  

NASA Astrophysics Data System (ADS)

Zircon occurs as a common accessory mineral in igneous, metamorphic and sedimentary rocks, and maintains much information on thermal history, metamorphic process and natural radiation dose accumulated in the mineral. U-Pb zircon dating (e.g., SHRIMP) is an important tool to interpret a history of the minerals at a micrometer-scale, where cathodoluminescence (CL) image has been used for identification of internal zones and domains having different chemical compositions and/or structures with a high spatial resolution. The CL of zircon is derived from various types of emission centers, which are derived from impurities such as rare earth elements (REE) and structural defects. In fact, the CL features of zircon are closely related to metamorphic process and radiation from contained radionuclides as well as geochemical condition of its formation. Most zircon has yellow emission, which seems to be assigned to UO2 centers or radiation-induced defect during metamictization of the lattice by alpha particles from the decay of U and Th. In this study, the radiation effects on zircon CL have been studied for He+ ion-implanted samples annealed at various temperatures to clarify radiation-induced defect centers involved with the yellow CL emission in zircon. Single crystals of zircon from Malawi (MZ), Takidani granodiorite (TZ) and Kurobegawa granite (KZ) were selected for He+ ion implantation experiments. The polished plates of the samples were implanted by He+ ion 4.0 MeV corresponding to energy of alpha particle from 238 U and 232Th. CL spectra in the range from 300 to 800 nm with 1 nm step were measured by a scanning electron microscopy-cathodoluminescence (SEM-CL). CL spectra of untreated and annealed zircon show emission bands at ~370 nm assigned to intrinsic defect centers and at ~480, ~580 and ~760 nm to trivalent Dy impurity centers (Cesbron et al., 1995; Gaft et al, 2005). CL emissions in the yellow-region were observed in untreated zircon. The TZ and KZ indicate youngest formation ages of 1.93-1.20 Ma and 1.7-0.9 Ma, respectively (Harayama,1994; Harayama et al., 2010) in the world. In this case, it is hardly to detect yellow CL emissions derived from radiation-induced defect center, suggesting low radiation dose of alpha radiation from 238U and 232Th on them. CL spectra of MZ, TZ and KZ showed an increase in the intensities of yellow emissions with an increase in radiation dose of He+ ion implantation, though He+ ion implantation reduces the intensities of their impurity centers. CL intensity in the yellow region depends on radiation dose of He+ ion implantation. Therefore, if the component of yellow emission could be deconvoluted from the CL spectra in zircon, its intensity will be used for an indicator to evaluate total exposure doses on it during geological age.

Tsuchiya, Y.; Nishido, H.; Kayama, M.; Noumi, Y.

2013-12-01

85

Shear-induced mixing governs codeformation of crystalline-amorphous nanolaminates.  

PubMed

Deformation of ductile crystalline-amorphous nanolaminates is not well understood due to the complex interplay of interface mechanics, shear banding, and deformation-driven chemical mixing. Here we present indentation experiments on 10 nm nanocrystalline Cu-100 nm amorphous CuZr model multilayers to study these mechanisms down to the atomic scale. By using correlative atom probe tomography and transmission electron microscopy we find that crystallographic slip bands in the Cu layers coincide with noncrystallographic shear bands in the amorphous CuZr layers. Dislocations from the crystalline layers drag Cu atoms across the interface into the CuZr layers. Also, crystalline Cu blocks are sheared into the CuZr layers. In these sheared and thus Cu enriched zones the initially amorphous CuZr layer is rendered into an amorphous plus crystalline nanocomposite. PMID:25083653

Guo, Wei; Jägle, Eric A; Choi, Pyuck-Pa; Yao, Jiahao; Kostka, Aleksander; Schneider, Jochen M; Raabe, Dierk

2014-07-18

86

Ultrafast Laser Induced Thermo-Elasto-Visco-Plastodynamics in Single Crystalline Silicon  

E-print Network

A comprehensive model for describing the fundamental mechanism dictating the interaction of ultrafast laser pulse with single crystalline silicon wafer is formulated. The need for establishing the feasibility of employing lasers of subpicosecond...

Qi, Xuele

2011-02-22

87

Radiation-Induced Spinal Cord Hemorrhage (Hematomyelia)  

PubMed Central

Intraspinal hemorrhage is very rare and intramedullary hemorrhage, also called hematomyelia, is the rarest form of intraspinal hemorrhage, usually related to trauma. Spinal vascular malformations such intradural arteriovenous malformations are the most common cause of atraumatic hematomyelia. Other considerations include warfarin or heparin anticoagulation, bleeding disorders, spinal cord tumors. Radiation-induced hematomyelia of the cord is exceedingly rare with only one case in literature to date. We report the case of an 8 year old girl with Ewing’s sarcoma of the thoracic vertebra, under radiation therapy, presenting with hematomyelia. We describe the clinical course, the findings on imaging studies and the available information in the literature. Recognition of the clinical pattern of spinal cord injury should lead clinicians to perform imaging studies to evaluate for compressive etiologies. PMID:25568739

Agarwal, Amit; Kanekar, Sangam; Thamburaj, Krishnamurthy; Vijay, Kanupriya

2014-01-01

88

Countermeasures for Space Radiation Induced Malignancies and Acute Biological Effects  

Microsoft Academic Search

The hypothesis being evaluated in this research program is that control of radiation induced oxidative stress will reduce the risk of radiation induced adverse biological effects occurring as a result of exposure to the types of radiation encountered during space travel. As part of this grant work, we have evaluated the protective effects of several antioxidants and dietary supplements and

Ann Kennedy

2008-01-01

89

Theory Of Radiation-Induced Attenuation In Optical Fibers  

NASA Technical Reports Server (NTRS)

Improved theory of radiation-induced attenuation of light in optical fibers accounts for effects of dose rates. Based on kinetic aspects of fundamental physics of color centers induced in optical fibers by radiation. Induced attenuation is proportional to density of color centers, and part of this density decays by thermal-annealing/recombination process after irradiation.

Liu, Tsuen-Hsi; Johnston, Alan R.

1996-01-01

90

Radiation induced micrencephaly in guinea pigs  

SciTech Connect

A brain weight deficit of about 70 mg was induced at doses of approximately 75-mGy and a deficit of 60 mg was induced at 100 mGy. This confirms the effects projected and observed by Wanner and Edwards. Although the data do not demonstrate a clear dose-response relationship between the 75-mGy and 100-mGy groups, the data are statistically consistent with a dose-response effect because of the overlapping confidence intervals. The lack of a statistically significant observation is most likely related to the small difference in doses and the limited numbers of animals examined. There are several factors that can influence the brain weight of guinea pig pups, such as caging and housing conditions, the sex of the animal, and litter size. These should be taken into account for accurate analysis. Dam weight did not appear to have a significant effect. The confirmation of a micrencephalic effect induced x rays at doses of 75-mGy during this late embryonic stage of development is consistent with the findings of small head size induced in those exposed prior to the eight week of conception at Hiroshima. This implies a mechanism for micrencephaly different from those previously suggested and lends credence to a causal relation between radiation and small head size in humans at low doses as reported by Miller and Mulvihill. 16 refs., 13 tabs.

Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

1991-01-01

91

Radiation-induced uterine changes: MR imaging  

SciTech Connect

To assess the capability of magnetic resonance (MR) imaging to demonstrate postirradiation changes in the uterus, MR studies of 23 patients who had undergone radiation therapy were retrospectively examined and compared with those of 30 patients who had not undergone radiation therapy. MR findings were correlated with posthysterectomy histologic findings. In premenopausal women, radiation therapy induced (a) a decrease in uterine size demonstrable as early as 3 months after therapy ended; (b) a decrease in signal intensity of the myometrium on T2-predominant MR images, reflecting a significant decrease in T2 relaxation time, demonstrable as early as 1 month after therapy; (c) a decrease in thickness and signal intensity of the endometrium demonstrable on T2-predominant images 6 months after therapy; and (d) loss of uterine zonal anatomy as early as 3 months after therapy. In postmenopausal women, irradiation did not significantly alter the MR imaging appearance of the uterus. These postirradiation MR changes in both the premenopausal and postmenopausal uteri appeared similar to the changes ordinarily seen on MR images of the nonirradiated postmenopausal uterus.

Arrive, L.; Chang, Y.C.; Hricak, H.; Brescia, R.J.; Auffermann, W.; Quivey, J.M.

1989-01-01

92

Generation of high-amplitude soliton waves in crystalline materials of different dimensions under high radiative, dynamic, and temperature loads  

SciTech Connect

It is shown that beams of high-amplitude supersonic breather solitons, phonons, and subsonic excitations of new type (torsions) are generated in crystalline materials of different dimensions under high radiative and dynamic loads near the stability threshold. The dispersion dependences of solitons and phonons in 1D crystals are presented. It is shown that, in 2D crystals beams consisting of six or two (depending on the bombarding particle direction), breather solitons are generated and propagate in certain crystallographic directions. The masses of soliton excitations as particles (coupled complexes of massless phonons) have been determined. It is shown that the subsonic soliton waves of a new type with torsion atomic vibrations are generated in 3D nanotubes, along with supersonic soliton waves of longitudinal vibrations.

Dubovsky, O. A., E-mail: dubov@ippe.ru; Orlov, A. V. [Leipunsky Institute for Physics and Power Engineering, State Scientific Center of the Russian Federation (Russian Federation)

2011-12-15

93

Amorphous silicon/crystalline silicon heterojunctions for nuclear radiation detector applications  

SciTech Connect

Results on characterization of electrical properties of amorphous Si films for the 3 different growth methods (RF sputtering, PECVD [plasma enhanced], LPCVD [low pressure]) are reported. Performance of these a-Si films as heterojunctions on high resistivity p-type and n- type crystalline Si is examined by measuring the noise, leakage current, and the alpha particle response of 5mm dia detector structures. It is demonstrated that heterojunction detectors formed by RF sputtered films and PECVD films are comparable in performance with conventional surface barrier detectors. Results indicate that the a-Si/c-Si heterojunctions have the potential to greatly simplify detector fabrication. Directions for future avenues of nuclear particle detector development are indicated.

Walton, J.T.; Hong, W.S.; Luke, P.N.; Wang, N.W. [Lawrence Berkeley National Lab., CA (United States); Ziemba, F.P. [Quantrad Sensor, Inc., Santa Clara, CA (United States)

1996-10-01

94

Geometric pumping induced by shear flow in dilute liquid crystalline polymer solutions  

E-print Network

We investigate nonlinear rheology of dilute liquid crystalline polymer solutions under time dependent two-directional shear flow. We analyze the Smoluchowski equation, which describes the dynamics of the orientation of a liquid crystalline polymer, by employing technique of the full counting statistics. In the adiabatic limit, we derive the expression for time integrated currents generated by a Berry-like curvature. Using this expression, it is shown that the expectation values of the time-integrated angular velocity of a liquid crystalline polymer and the time-integrated stress tensor are generally not zero even if the time average of the shear rate is zero. The validity of the theoretical calculations is confirmed by direct numerical simulations of the Smoluchowski equation. Nonadiabatic effects are also investigated by simulations and it is found that the time-integrated stress tensor depends on the speed of the modulation of the shear rate if we adopt the isotropic distribution as an initial state.

Shunsuke Yabunaka; Hisao Hayakawa

2014-12-08

95

Geometric pumping induced by shear flow in dilute liquid crystalline polymer solutions  

NASA Astrophysics Data System (ADS)

We investigate nonlinear rheology of dilute liquid crystalline polymer solutions under time dependent two-directional shear flow. We analyze the Smoluchowski equation, which describes the dynamics of the orientation of a liquid crystalline polymer, by employing technique of the full counting statistics. In the adiabatic limit, we derive the expression for time integrated currents generated by a Berry-like curvature. Using this expression, it is shown that the expectation values of the time-integrated angular velocity of a liquid crystalline polymer and the time-integrated stress tensor are generally not zero even if the time average of the shear rate is zero. The validity of the theoretical calculations is confirmed by direct numerical simulations of the Smoluchowski equation. Nonadiabatic effects are also investigated by means of simulations and it is found that the time-integrated stress tensor depends on the speed of the modulation of the shear rate if we adopt the isotropic distribution as an initial state.

Yabunaka, Shunsuke; Hayakawa, Hisao

2015-02-01

96

The Formation of Crystalline Dust in AGB Winds from Binary Induced Spiral Shocks  

E-print Network

As stars evolve along the Asymptotic Giant Branch, strong winds are driven from the outer envelope. These winds form a shell, which may ultimately become a planetary nebula. Many planetary nebulae are highly asymmetric, hinting at the presence of a binary companion. Some post-Asymptotic Giant Branch objects are surrounded by torii of crystalline dust, but there is no generally accepted mechanism for annealing the amorphous grains in the wind to crystals. In this Letter, we show that the shaping of the wind by a binary companion is likely to lead to the formation of crystalline dust in the orbital plane of the binary.

R. G. Edgar; J. Nordhaus; E. Blackman; A. Frank

2007-09-14

97

Radiation-pressure-induced regenerative mechanical oscillations in  

E-print Network

-Pressure Induced Mechanical Oscillation of an optical Microcavity" Physical Review Letters, Volume 95, 033901, JulyRadiation-pressure-induced regenerative mechanical oscillations in optical microcavities Hossein Physics Department California Institute of Technology APS March meeting 2006 #12;Microtoroid optical

98

Ion beam induced luminescence: Relevance to radiation induced bystander effects  

NASA Astrophysics Data System (ADS)

The aim of this work is quantify the light emitted as a result of charged particle interaction in materials which may be of relevance to radiation induced "bystander effects" studies. We have developed a system which employs single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. The system uses a fast photomultiplier tube with a peak cathode response at 420 nm. It has been tested in a proof-of-principle experiment using polystyrene targets. Light output, as a result of irradiation, was measured. The luminescence yield appears to have a non-linear behavior with the incident ion fluence: it rises exponentially to an asymptotic value. The target was irradiated with beam energies varying from 1 to 2 MeV and showed saturation at or before an incident fluence rate of 3 × 1013 H+/cm2 s. The average saturation value for the photon output was found to be 40 × 106 cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28 × 103, 10 × 106, and 35 × 106 cps for wavelengths of 280 ± 5 nm, 320 ± 5 nm and 340 ± 5 nm respectively. The light output reaches a maximum value because of damage induced in the polymer. Our measurements indicate a "damage cross section" of the order of 10-14 cm2. The average radiant intensity was found to increase at wavelengths of 280 and 320 nm when the proton energy was increased. This was not found to occur at 340 nm. In conclusion, the light emission at specific wavelengths was found to depend upon the incident proton fluence and the proton energy. The wavelengths of the emitted light measured in this study have significance for the understanding of radiation induced bystander effects.

Ahmad, S. B.; McNeill, F. E.; Byun, S. H.; Prestwich, W. V.; Seymour, C.; Mothersill, C. E.

2012-10-01

99

The effect of molecular motion on radiation-induced chain scission and racemization of iso-poly(methyl methacrylate)  

Microsoft Academic Search

In this paper, the radiation-induced chain scission and racemization of isotactic poly(methyl methacrylate) (iso-PMMA) in amorphous, solid, crystalline state and in solution have been studied with nuclear magnetic resonance and molecular weight determination. It is shown that the chain scission is the most prior effect for iso-PMMA in its dilute solution and the racemization reaction is the inferior one in

Luo Yunxia; Yang Hong; Li Shuhua; Yu Bin; Ding Mengxian; Jiang Bingzhen

1993-01-01

100

Effect of Laser Induced Crystallinity Modification on Biodegradation Profile of Poly(L-Lactic Acid)  

E-print Network

University, New York, NY 10027 Abstract Poly(L-lactic acid) (PLLA) is of interest in drug delivery: poly(L-lactic acid); laser treatment; biodegradation; crystallinity; drug delivery #12;2 1. Introduction Poly(L-lactic acid) (PLLA) is attractive in drug delivery, food packaging, and tissue engineering

Yao, Y. Lawrence

101

Analysis of radiation pressure induced nonlinear optofluidics.  

PubMed

We analyze two nonlinear optofluidic processes where nonlinearity is induced by the interplay between optical field and liquid interface. Specifically, guided optical waves generate radiation pressure on the liquid interface, which can in turn distort the liquid interface and modify the properties of the optical field. In the first example, we discuss the feasibility of nonlinear optofluidic solitons, where optical field is governed by the nonlinear Schrödinger equation and nonlinearity is effectively determined by liquid properties. Then, we analyze a nonlinear optofluidic process associated with a high quality (Q) factor whispering gallery mode (WGM) in a liquid droplet. Similar to Kerr effects, the WGM can produce a frequency shift proportional to the WGM power. Using liquid properties that are experimentally attainable, we find that it may only take a few photons to generate measurable WGM resonance shift. Such a possibility may eventually lead to nonlinear optics at single photon energy level. PMID:25402127

Xu, Yong; Zhang, Peng; Jung, Sunghwan; Lee, Aram

2014-11-17

102

INTERACTION OF LASER RADIATION WITH MATTER: Generation of a bleaching wave in an ST-50-1 glass ceramics induced by a Nd:YAG laser  

NASA Astrophysics Data System (ADS)

It is shown that upon exposing glass ceramics to laser radiation for which the initial polycrystalline phase is opaque, whereas the corresponding glass phase is transparent, the transparency oscillations can be produced due to the laser-induced phase transitions from the crystalline to amorphous state and vice versa, resulting in the propagation of a bleaching and darkening wave.

Veiko, V. P.; Novikov, B. Yu; Shakhno, E. A.; Yakovlev, E. B.

2009-01-01

103

Radiation-induced degradation of DNA bases  

NASA Astrophysics Data System (ADS)

Radio-induced degradation of DNA involves radical processes. A series of lesions among the major bases degradation products 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 four bases are degraded in high yield. Direct effect has been mimicked by photo-induced electron abstraction from the bases producing their radical cation. Quantification of the modified bases showed that guanine is the preferential target. This can be explained by its lower oxidation potential and charge transfer phenomena. La décomposition radio-induite de l'ADN fait intervenir des processus radicalaires. Une série de lésions choisies parmi les produits majeurs de dégradation des bases a été mesurée dans de l'ADN isolé exposé au rayonnement en solution aqueuse aérée. Les modifications sont alors dues aux radicaux hydroxyles produits par la radiolyse de l'eau (effet indirect) et les quatre bases sont efficacement dégradées. L'arrachement d'électrons aux bases par photosensibilisation pour produire leur radical cation, a été utilisé comme modèle de l'effet direct. La quantification des bases modifiées montre que la guanine est préférentiellement dégradée. Cette observation peut s'expliquer par le plus faible potentiel d'oxydation de cette base ainsi que par les phénomènes de transfert de charge vers les guanines.

Douki, T.; Delatour, T.; Martini, R.; Cadet, J.

1999-01-01

104

[Search for chaperon-like anticataract drugs, the antiaggregants of lens crystallins. Communication. 1. Chaperon-like activity of N-acetyl carnosine dipeptide: in vitro study on a model of ultraviolet-induced aggregation of betaL-crystallin].  

PubMed

Aggregation ofcrystallins, the lens proteins, is one of the basic stages of cataract formation. Among the protein aggregation models used to study the molecular mechanisms of the initial stages of lenticular opacity, UV-induced aggregation of betaL-crystallin is most close to the in vivo conditions. The carnosine derivative N-acetyl carnosine has been shown to be effective in inhibiting the UV-induced aggregation of betaL-crystallin. Examination of the accumulation kinetics of carbonyl groups in betaL-crystallin under UV irradiation has indicated that neither carnosine nor N-acetyl carnosine fails to affect this parameter--an indicator of oxidative protein damage. By taking into account also the fact that N-acetyl carnosine is not an antioxidant, it can be believed that the molecular mechanism of action of this compound on UV-induced aggregation of betaL is unassociated with its antioxidative properties. The authors hypothesize that the molecular chaperon-like properties similar to those of alpha-crystallin underlie the mechanism of action of the acetyl derivative carnosine. The prospects for searching anticataract agents of a new chaperon-like class are discussed. PMID:18488459

Muranov, K O; Dizhevskaia, A K; Boldyrev, A A; Karpova, O E; Sheremet, N L; Polunin, G S; Avetisov, S E; Ostrovski?, M A

2008-01-01

105

Obstructive jaundice due to radiation-induced hepatic duct stricture  

SciTech Connect

A case of obstructive jaundice due to radiation-induced hepatic duct stricture is reported. The patient received postoperative radiation for left adrenal carcinoma, seven years prior to this admission. The sequelae of hepatobiliary radiation and their management are discussed briefly.

Chandrasekhara, K.L.; Iyer, S.K.

1984-10-01

106

Alpha-decay-induced fracturing in zircon - The transition from the crystalline to the metamict state  

NASA Technical Reports Server (NTRS)

Zonation due to alpha-decay damage in a natural single crystal of zircon from Sri Lanka is discussed. The zones vary in thickness on a scale from one to hundreds of microns. The uranium and thorium concentrations vary from zone to zone such that the alpha decay dose is between 0.2 x 10 to the 16th and 0.8 x 10 to the 16th alpha-events per milligram. The transition from the crystalline to the aperiodic metamict state occurs over this dose range. At doses greater than 0.8 x 10 to the 16th alpha events/mg there is no evidence for long-range order. This type of damage will accumulate in actinide-bearing, ceramic nuclear waste forms. The systematic pattern of fractures would occur in crystalline phases that are zoned with respect to actinide radionuclides.

Chakoumakos, Bryan C.; Murakami, Takashi; Lumpkin, Gregory R.; Ewing, Rodney C.

1987-01-01

107

Excitation Spectrum of Crystalline Tetracene Fluorescence: A Probe for Optically-Induced Singlet-Exciton Fission  

Microsoft Academic Search

The intrinsic fluorescence efficiency of crystalline tetracene depends on the energy of the exiciting light. It decreases for Eexc > 2.48 eV displaying a minimum at Eexc = 2.51 eV which is identical with the energy of the triplet pair state. It is suggested that an optically populated, vibronically excited S 1-state. which is iso-energetic with the triplet pair state

G. Vaubel; H. Baessler

1971-01-01

108

Geometric pumping induced by shear flow in dilute liquid crystalline polymer solutions.  

PubMed

We investigate nonlinear rheology of dilute liquid crystalline polymer solutions under time dependent two-directional shear flow. We analyze the Smoluchowski equation, which describes the dynamics of the orientation of a liquid crystalline polymer, by employing technique of the full counting statistics. In the adiabatic limit, we derive the expression for time integrated currents generated by a Berry-like curvature. Using this expression, it is shown that the expectation values of the time-integrated angular velocity of a liquid crystalline polymer and the time-integrated stress tensor are generally not zero even if the time average of the shear rate is zero. The validity of the theoretical calculations is confirmed by direct numerical simulations of the Smoluchowski equation. Nonadiabatic effects are also investigated by means of simulations and it is found that the time-integrated stress tensor depends on the speed of the modulation of the shear rate if we adopt the isotropic distribution as an initial state. PMID:25662664

Yabunaka, Shunsuka; Hayakawa, Hisao

2015-02-01

109

Transcriptional regulation of crystallin, redox, and apoptotic genes by C-Phycocyanin in the selenite-induced cataractogenic rat model  

PubMed Central

Purpose This study was designed to examine the constrictive potential of C-Phycocyanin (C-PC) in regulating changes imposed on gene expression in the selenite-induced cataract model. Methods Wistar rat pups were divided into three groups of eight each. On P10, Group I received an intraperitoneal injection of normal saline. Groups II and III received a subcutaneous injection of sodium selenite (19 ?mol/kg bodyweight); Group III also received an intraperitoneal injection of C-PC (200 mg/kg bodyweight) on P9–14. Total RNA was isolated on P16, and the relative abundance of mRNA of the crystallin structural genes, redox components, and apoptotic cascade were ascertained with real-time PCR with reference to the internal control ?-actin. Results Real-time PCR analysis showed the crystallin genes (?A-, ?B1-, ?D-) and redox cycle components (Cat, SOD-1, Gpx) were downregulated, the apoptotic components were upregulated, and antiapoptotic Bcl-2 was downregulated in Group II. Treatment with 200 mg/kg bodyweight C-PC (Group III) transcriptionally regulated the instability of the expression of these genes, thus ensuring C-PC is a prospective anticataractogenic agent that probably delays the onset and progression of cataractogenesis induced by sodium selenite. Conclusions C-PC treatment possibly prevented cataractogenesis triggered by sodium selenite, by regulating the lens crystallin, redox genes, and apoptotic cascade mRNA expression and thus maintains lens transparency. C-PC may be developed as a potential antioxidant compound applied in the future to prevent and treat age-related cataract. PMID:25593511

Kumari, Rasiah Pratheepa; Ramkumar, Srinivasagan; Thankappan, Bency; Natarajaseenivasan, Kalimuthusamy; Balaji, Sadhasivam

2015-01-01

110

Suppression of DTT-induced aggregation of abrin by alphaA- and alphaB-crystallins: a model aggregation assay for alpha-crystallin chaperone activity in vitro.  

PubMed

The eye lens small heat shock proteins (sHSP), alphaA- and alphaB-crystallins, have been shown to function like molecular chaperones, both in vitro and in vivo. It is essential to assess the protective effect of alphaA- and alphaB-crystallins under native conditions to extrapolate the results to in vivo conditions. Insulin and alpha-lactalbumin have widely been used to investigate the chaperone mechanism of alpha-crystallin under native conditions. Due to its smaller size, insulin B-chain may not represent the binding of putative physiological substrate proteins. As it stands, the aggregation of alpha-lactalbumin and binding of alpha-crystallin to it varies under different experimental conditions. Abrin, a ribosome inactivating protein isolated from the seeds of Abrus precatorius, consists of a 30 kDa A-chain and a lectin-like B-chain of 33 kDa joined by a single disulfide bond. Reduction of the disulfide link between the two chains of abrin leads to the aggregation of the B-chain. In this study, we demonstrate that dithiothreitol (DTT)-induced aggregation of abrin B-chain could be monitored by light scattering similar to that of insulin. Moreso, this process could be suppressed by recombinant human alphaA- and alphaB-crystallins in a concentration dependent manner, notably by binding to aggregation prone abrin B-chain. SDS-PAGE and HPLC gel filtration analysis indicate that there is a soluble complex formation between alpha-crystallin and abrin B-chain. Interestingly, in contrast to insulin, there is no significant difference between alphaA- and alphaB-crystallin in suppressing the aggregation of abrin B-chain at two different temperatures (25 and 37 degrees C). HSP26, an another small heat shock/alpha-crystallin family protein, was also able to prevent the DTT-induced aggregation of abrin. These results suggest that due to relatively larger size of its B-chain (33 kDa), compared to insulin B-chain (about 3 kDa), abrin may serve as a better model substrate for in vitro chaperone studies of alpha-crystallin and as well as other sHSP. PMID:12095619

Reddy, G Bhanuprakash; Narayanan, Sriram; Reddy, P Yadagiri; Surolia, Ira

2002-07-01

111

Pulsed Green-Laser Annealing for Single-Crystalline Silicon Film Transferred onto Silicon wafer and Non-alkaline Glass by Hydrogen-Induced Exfoliation  

Microsoft Academic Search

A single-crystalline Si film was transferred onto a Si wafer and non-alkaline glass by hydrogen-induced exfoliation and the effect of pulsed green-laser annealing was investigated. Above a laser energy of 1285 mJ\\/cm2, the crystallinity of the Si film was recovered both on the Si wafer and the glass. The linewidth of micro-Raman spectra of the Si film on the Si

Norihito Kawaguchi; Ryusuke Kawakami; Ken-ichiro Nishida; Naoya Yamamoto; Miyuki Masaki; Atsushi Yoshinouchi

2007-01-01

112

Spatial distribution of radiation damage to crystalline proteins at 25–300?K  

PubMed Central

The spatial distribution of radiation damage (assayed by increases in atomic B factors) to thaumatin and urease crystals at temperatures ranging from 25 to 300?K is reported. The nature of the damage changes dramatically at approximately 180?K. Above this temperature the role of solvent diffusion is apparent in thaumatin crystals, as solvent-exposed turns and loops are especially sensitive. In urease, a flap covering the active site is the most sensitive part of the molecule and nearby loops show enhanced sensitivity. Below 180?K sensitivity is correlated with poor local packing, especially in thaumatin. At all temperatures, the component of the damage that is spatially uniform within the unit cell accounts for more than half of the total increase in the atomic B factors and correlates with changes in mosaicity. This component may arise from lattice-level, rather than local, disorder. The effects of primary structure on radiation sensitivity are small compared with those of tertiary structure, local packing, solvent accessibility and crystal contacts. PMID:22948911

Warkentin, Matthew; Badeau, Ryan; Hopkins, Jesse B.; Thorne, Robert E.

2012-01-01

113

Radiation-induced segregation in complex alloys  

SciTech Connect

Radiation-induced segregation (RIS) of alloying elements to the surface during 3 MeV /sup 58/Ni/sup +/ ion bombardment was investigated in alloys of Fe-200Cr-12Ni (at. %) containing controlled additions of Si and Mo. The segregation profiles, determined by Auger electron spectroscopy, show that Ni and Si are enriched, while Cr and Mo are depleted at the irradiated surfaces. The data indicates that the RIS of Ni and Cr are affected by the presence of Mo and Si in the alloy. However, no obvious trends are observed as a function of the minor solute element concentration. The temperature dependence of the RIS of the alloying elements was also investigated. A maximum of segregation at approx. 500/sup 0/C is observed for Si followed by a minimum and then a sharp increase in segregation at temperatures above 600/sup 0/C. The temperature dependence of segregation for Cr, Ni and Mo shows continous increase with temperature in the temperature regime investigated. The void swelling data on these alloys is also presented as a function of temperature and composition. Additions of Si reduce the swelling by affecting both the nucleation and the growth of the voids. The peak swelling temperature for all the alloys containing minor solutes are found to be lower (approx. 50/sup 0/C) than that of the base alloy (peak swelling temperature approx. 660/sup 0/C).

Sethi, V.K.; Okamoto, P.R.

1980-01-01

114

Radiation exposure induces inflammasome pathway activation in immune cells.  

PubMed

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

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

2015-02-01

115

Towards high efficiency thin-film crystalline silicon solar cells: The roles of light trapping and non-radiative recombinations  

SciTech Connect

Thin-film solar cells based on silicon have emerged as an alternative to standard thick wafers technology, but they are less efficient, because of incomplete absorption of sunlight, and non-radiative recombinations. In this paper, we focus on the case of crystalline silicon (c-Si) devices, and we present a full analytic electro-optical model for p-n junction solar cells with Lambertian light trapping. This model is validated against numerical solutions of the drift-diffusion equations. We use this model to investigate the interplay between light trapping, and bulk and surface recombination. Special attention is paid to surface recombination processes, which become more important in thinner devices. These effects are further amplified due to the textures required for light trapping, which lead to increased surface area. We show that c-Si solar cells with thickness of a few microns can overcome 20% efficiency and outperform bulk ones when light trapping is implemented. The optimal device thickness in presence of light trapping, bulk and surface recombination, is quantified to be in the range of 10–80??m, depending on the bulk quality. These results hold, provided the effective surface recombination is kept below a critical level of the order of 100?cm/s. We discuss the possibility of meeting this requirement, in the context of state-of-the-art techniques for light trapping and surface passivation. We show that our predictions are within the capability of present day silicon technologies.

Bozzola, A., E-mail: angelo.bozzola@unipv.it; Kowalczewski, P.; Andreani, L. C. [Physics Department, University of Pavia and CNISM, via Bassi 6, I-27100 Pavia (Italy)

2014-03-07

116

Wet milling induced physical and chemical instabilities of naproxen nano-crystalline suspensions.  

PubMed

Wet-milling is the most common approach to formulate nano-crystalline suspensions. The effect of high intensity wet-milling on the physical and chemical stability of a poorly soluble drug was investigated. Naproxen (1%, w/v) was suspended in two different stabilizers (i.e. HPMC E15 and Tween 80) and stabilizer concentrations (0.2% or 0.6%, w/v) in distilled water. Wet-milling was performed at two different speeds (i.e. 3,400 rpm and 2,000 rpm) for four continuous hours. The milled samples were analyzed for physical and chemical instabilities. Wet-milling of naproxen-HPMC E15 at high milling intensity caused both physical and chemical instabilities as observed by particle size measurement and chemical analysis, respectively. The naproxen-Tween 80 formulations were stable regardless of milling intensity. Naproxen-HPMC E15 wet-milled samples, showed an IR peak shift suggesting strong bond formation or molecular interaction (i.e. amorphous phase). In addition, naproxen has a strong interaction with HPMC E15 as determined by MTDSC (i.e. melting point depression). The generation of amorphous phase at the naproxen-HPMC E15 crystal surface may be responsible for both aggregation and degradation during wet milling. Decarboxylated naproxen was identified as a degradation product. Milling intensity and/or selection of stabilizer/s are crucial for the stability of nano-crystalline suspensions. PMID:24614581

Kumar, Sumit; Burgess, Diane J

2014-05-15

117

Radiation-Induced Cavernomas of the Brain  

Microsoft Academic Search

Summary: The purpose of this report is to add support to the growing literature that there is a correlation between radiation and cavernomas of the brain, particularly if the radiation is received in childhood, as well as to increase awareness of this correlation in the radiology community. Retrospective review of our experience returned five pa- tients who received radiation therapy

Rajan Jain; Patricia L. Robertson; Dheeraj Gandhi; Sachin K. Gujar; Karin M. Muraszko; Stephen Gebarski

118

Silica-based cerium (III) chloride nanoparticles prevent the fructose-induced glycation of ?-crystallin and H?O?-induced oxidative stress in human lens epithelial cells.  

PubMed

This study aimed to investigate whether silica-cerium (III) chloride (CeCl3) nanoparticles could inhibit the formation of advanced glycation end-products (AGEs) and reduce oxidative stress. Silica-CeCl3 nanoparticles were synthesised by adsorption and embedment with micro-silica materials, forming uniform nanoparticles with a diameter of approximately 130 nm. Chaperone activity assays and AGEs formation assays, and intracellular reactive assays were adopted in this study to evaluate CeCl3 nanoparticles effect. UV-visible spectrometry showed that silica-CeCl3 nanoparticles at low concentrations rapidly formed tentatively stable conjugations with ?-crystallin, greatly enhancing the chaperone activity of ?-crystallin. Moreover, silica-CeCl3 nanoparticles markedly inhibited the fructose-induced glycation of ?-crystallin, showing an advantage over the control drugs aminoguanidine and carnosine. Silica-CeCl3 nanoparticles also reduced intracellular reactive oxygen species production and restored glutathione levels in H2O2-treated human lens epithelial cells. These findings suggest that silica-CeCl3 may be used as a novel agent for the prevention of cataractogenesis. PMID:23828754

Yang, Jin; Cai, Lei; Zhang, Sen; Zhu, Xiangjia; Zhou, Peng; Lu, Yi

2014-03-01

119

Effect of radiation induced crosslinking and degradation of ETFE films  

NASA Astrophysics Data System (ADS)

In this study the ETFE film with 125 ?m of thickness was placed inside a nylon bag and filled with either acetylene, nitrogen or oxygen. Following the procedure, the samples were irradiated at 5, 10 and 20 kGy. The physical and chemical properties of the modified and pristine films were evaluated by rheological and thermal analyses (TG and DSC), X-ray diffraction (XRD) and infrared spectroscopy (IR-ATR). In rheological analysis the storage modulus (G') indicates opposite profiles when the atmospheres (acetylene and oxygen) are evaluated according to the absorbed dose. For the samples submitted to radiation under oxygen atmosphere it is possible to observe the degradation process with the low levels of the storage modulus. The changes in the degree of crystallinity were verified in all modified samples when compared to the pristine polymer and this behavior was confirmed by DSC analysis. A decrease in the intensity of crystalline peak by X-ray diffraction was observed.

Zen, H. A.; Ribeiro, G.; Geraldes, A. N.; Souza, C. P.; Parra, D. F.; Lugão, A. B.

2013-03-01

120

Single-crystalline Si on insulator in confined structures fabricated by two-step metal-induced crystallization of amorphous Si  

NASA Astrophysics Data System (ADS)

We present a technology and its mechanism to obtain single-crystalline Si pillars on SiO2 using a two-step Ni-induced crystallization process on amorphous Si pillars with confined sizes. The amorphous Si pillars with a Ni cap were first annealed at 400 °C for 15 h so that a single-crystalline NiSi2 template was formed on top of each pillar. In the second step, they were annealed at 550 °C for 2 h, during which single-crystalline Si pillars were formed by NiSi2-mediated solid-phase epitaxy. These single-crystalline Si pillars can be used for advanced vertical metal-oxide-semiconductor transistors and surround-gate structures, especially where low-temperature processing is required.

Liu, Yaocheng; Deal, Michael D.; Saraswat, Krishna C.; Plummer, James D.

2002-12-01

121

Temperature-induced reversible self-assembly of diphenylalanine peptide and the structural transition from organogel to crystalline nanowires  

PubMed Central

Controlling the self-assembly of diphenylalanine peptide (FF) into various nanoarchitectures has received great amounts of attention in recent years. Here, we report the temperature-induced reversible self-assembly of diphenylalanine peptide to microtubes, nanowires, or organogel in different solvents. We also find that the organogel in isopropanol transforms into crystalline flakes or nanowires when the temperature increases. The reversible self-assembly in polar solvents may be mainly controlled by electronic and aromatic interactions between the FF molecules themselves, which is associated with the dissociation equilibrium and significantly influenced by temperature. We found that the organogel in the isopropanol solvent made a unique transition to crystalline structures, a process that is driven by temperature and may be kinetically controlled. During the heating-cooling process, FF preferentially self-assembles to metastable nanofibers and organogel. They further transform to thermodynamically stable crystal structures via molecular rearrangement after introducing an external energy, such as the increasing temperature used in this study. The strategy demonstrated in this study provides an efficient way to controllably fabricate smart, temperature-responsive peptide nanomaterials and enriches the understanding of the growth mechanism of diphenylalanine peptide nanostructures. PMID:25520600

2014-01-01

122

Topological phase transition in a topological crystalline insulator induced by finite-size effects  

NASA Astrophysics Data System (ADS)

We study electronic states and topological invariants of (001) films of the topological crystalline insulator (TCI) PbxSn1-xTe. Gapless surface Dirac cones on bulk TCIs become gapped in thin films due to the finite-size effect, which is the hybridization between the states on the top and bottom surfaces. We clarify that the TCI film has a strong finite-size effect as compared to three-dimensional topological insulators such as Bi2Se3. Moreover, the energy gap oscillates with the thickness of film. The oscillation stems from topological phase transitions in two dimensions. The obtained data of the topological invariants and energy gap serve as guide to TCI-device applications.

Ozawa, Hideyuki; Yamakage, Ai; Sato, Masatoshi; Tanaka, Yukio

2014-07-01

123

Magnetic field-induced deformation in single- and poly-crystalline Ni2MnGa  

Microsoft Academic Search

Summary form only given. The shape changes of ferromagnetic shape memory alloys (FMSMAs) induced by magnetic field associated with structural and magnetic properties have been investigated to understand the relation between martensite transformation and magnetic properties. In the present study, two mechanisms explaining magnetic field-induced strain behavior and their related energy terms were introduced and shape change under magnetic field

S. J. Jeong; B. K. Min; D. W. Shin

2002-01-01

124

Formation of titanium monoxide (001) single-crystalline thin film induced by ion bombardment of titanium dioxide (110)  

NASA Astrophysics Data System (ADS)

A plethora of technological applications justify why titanium dioxide is probably the most studied oxide, and an optimal exploitation of its properties quite frequently requires a controlled modification of the surface. Low-energy ion bombardment is one of the most extended techniques for this purpose and has been recently used in titanium oxides, among other applications, to favour resistive switching mechanisms or to form transparent conductive layers. Surfaces modified in this way are frequently described as reduced and defective, with a high density of oxygen vacancies. Here we show, at variance with this view, that high ion doses on rutile titanium dioxide (110) induce its transformation into a nanometric and single-crystalline titanium monoxide (001) thin film with rocksalt structure. The discovery of this ability may pave the way to new technical applications of ion bombardment not previously reported, which can be used to fabricate heterostructures and interfaces.

Pabón, B. M.; Beltrán, J. I.; Sánchez-Santolino, G.; Palacio, I.; López-Sánchez, J.; Rubio-Zuazo, J.; Rojo, J. M.; Ferrer, P.; Mascaraque, A.; Muñoz, M. C.; Varela, M.; Castro, G. R.; de La Fuente, O. Rodríguez

2015-02-01

125

Formation of titanium monoxide (001) single-crystalline thin film induced by ion bombardment of titanium dioxide (110).  

PubMed

A plethora of technological applications justify why titanium dioxide is probably the most studied oxide, and an optimal exploitation of its properties quite frequently requires a controlled modification of the surface. Low-energy ion bombardment is one of the most extended techniques for this purpose and has been recently used in titanium oxides, among other applications, to favour resistive switching mechanisms or to form transparent conductive layers. Surfaces modified in this way are frequently described as reduced and defective, with a high density of oxygen vacancies. Here we show, at variance with this view, that high ion doses on rutile titanium dioxide (110) induce its transformation into a nanometric and single-crystalline titanium monoxide (001) thin film with rocksalt structure. The discovery of this ability may pave the way to new technical applications of ion bombardment not previously reported, which can be used to fabricate heterostructures and interfaces. PMID:25707936

Pabón, B M; Beltrán, J I; Sánchez-Santolino, G; Palacio, I; López-Sánchez, J; Rubio-Zuazo, J; Rojo, J M; Ferrer, P; Mascaraque, A; Muñoz, M C; Varela, M; Castro, G R; de la Fuente, O Rodríguez

2015-01-01

126

Heavy-ion radiation induced bystander effect in mice  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

127

Radiation-induced myeloid leukemia in murine models  

PubMed Central

The use of radiation therapy is a cornerstone of modern cancer treatment. The number of patients that undergo radiation as a part of their therapy regimen is only increasing every year, but this does not come without cost. As this number increases, so too does the incidence of secondary, radiation-induced neoplasias, creating a need for therapeutic agents targeted specifically towards incidence reduction and treatment of these cancers. Development and efficacy testing of these agents requires not only extensive in vitro testing but also a set of reliable animal models to accurately recreate the complex situations of radiation-induced carcinogenesis. As radiation-induced leukemic progression often involves genomic changes such as rearrangements, deletions, and changes in methylation, the laboratory mouse Mus musculus, with its fully sequenced genome, is a powerful tool in cancer research. This fact, combined with the molecular and physiological similarities it shares with man and its small size and high rate of breeding in captivity, makes it the most relevant model to use in radiation-induced leukemia research. In this work, we review relevant M. musculus inbred and F1 hybrid animal models, as well as methods of induction of radiation-induced myeloid leukemia. Associated molecular pathologies are also included. PMID:25062865

2014-01-01

128

Radiation-induced myeloid leukemia in murine models.  

PubMed

The use of radiation therapy is a cornerstone of modern cancer treatment. The number of patients that undergo radiation as a part of their therapy regimen is only increasing every year, but this does not come without cost. As this number increases, so too does the incidence of secondary, radiation-induced neoplasias, creating a need for therapeutic agents targeted specifically towards incidence reduction and treatment of these cancers. Development and efficacy testing of these agents requires not only extensive in vitro testing but also a set of reliable animal models to accurately recreate the complex situations of radiation-induced carcinogenesis. As radiation-induced leukemic progression often involves genomic changes such as rearrangements, deletions, and changes in methylation, the laboratory mouse Mus musculus, with its fully sequenced genome, is a powerful tool in cancer research. This fact, combined with the molecular and physiological similarities it shares with man and its small size and high rate of breeding in captivity, makes it the most relevant model to use in radiation-induced leukemia research. In this work, we review relevant M. musculus inbred and F1 hybrid animal models, as well as methods of induction of radiation-induced myeloid leukemia. Associated molecular pathologies are also included. PMID:25062865

Rivina, Leena; Davoren, Michael; Schiestl, Robert H

2014-01-01

129

The role of continuum radiation in laser induced plasma spectroscopy  

Microsoft Academic Search

This paper focuses on the interpretation of the origin of the continuum radiation in Laser Induced Plasma (LIP) emission spectra, a subject that has received little consideration in the literature when compared to the analysis of the line emission spectrum. The understanding of the spectral peculiarities observed immediately after the laser pulse, when the continuum radiation prevails on discrete emission

A. De Giacomo; R. Gaudiuso; M. Dell'Aglio; A. Santagata

2010-01-01

130

Crystalline Silica  

Cancer.gov

An abundant natural material, crystalline silica is found in stone, soil, and sand. It is also found in concrete, brick, mortar, and other construction materials. Crystalline silica comes in several forms, with quartz being the most common. Quartz dust is respirable crystalline silica, which means it can be taken in by breathing.

131

Protection from radiation-induced apoptosis by the radioprotector amifostine (WR-2721) is radiation dose dependent.  

PubMed

The radioprotective agent amifostine is a free radical scavenger that can protect cells from the damaging effects of ionising radiation when administered prior to radiation exposure. However, amifostine has also been shown to protect cells from chromosomal mutations when administered after radiation exposure. As apoptosis is a common mechanism by which cells with mutations are removed from the cell population, we investigated whether amifostine stimulates apoptosis when administered after radiation exposure. We chose to study a relatively low dose which is the maximum radiation dose for radiation emergency workers (0.25 Gy) and a high dose relevant to radiotherapy exposures (6 Gy). Mice were administered 400 mg/kg amifostine 30 min before, or 3 h after, whole-body irradiation with 0.25 or 6 Gy X-rays and apoptosis was analysed 3 or 7 h later in spleen and bone marrow. We observed a significant increase in radiation-induced apoptosis in the spleen of mice when amifostine was administered before or after 0.25 Gy X-rays. In contrast, when a high dose of radiation was used (6 Gy), amifostine caused a reduction in radiation-induced apoptosis 3 h post-irradiation in spleen and bone marrow similar to previously published studies. This is the first study to investigate the effect of amifostine on radiation-induced apoptosis at a relatively low radiation dose and the first to demonstrate that while amifostine can reduce apoptosis from high doses of radiation, it does not mediate the same effect in response to low-dose exposures. These results suggest that there may be a dose threshold at which amifostine protects from radiation-induced apoptosis and highlight the importance of examining a range of radiation doses and timepoints. PMID:24459009

Ormsby, Rebecca J; Lawrence, Mark D; Blyth, Benjamin J; Bexis, Katrina; Bezak, Eva; Murley, Jeffrey S; Grdina, David J; Sykes, Pamela J

2014-02-01

132

Impurity induced crystallinity and optical emissions in ZnO nanorod arrays  

NASA Astrophysics Data System (ADS)

We report the growth of ZnO nanocrystallites doped with impurities such as B, N and S by green chemistry route using ultrasound. The effect of intrinsic defects and impurity doping on the structural and optical properties of ZnO nanostructures has been studied and discussed. Characterization studies carried out using x-ray diffraction (XRD) reveal the change in lattice parameters and crystallinity of ZnO in the presence of dopant. This has been explained on the basis of the dopant substitution at regular anion and interstitial sites. Study on surface morphology by field emission scanning electron microscopy (FESEM) shows a change from particle-like structure to aligned nanorods nucleated at definite sites. Elemental analysis such as x-ray photon electron spectroscopy (XPS) has been carried out to ascertain the dopant configuration in ZnO. This has been corroborated by the results obtained from FTIR and Raman studies. UV–vis light absorption and PL studies show an expansion of the band gap which has been explained on the basis of Moss–Burstein shift in the electronic band gap of ZnO by impurity incorporation. The optical emissions corresponding to excitonic transition and defect centres present in the band gap of ZnO is found to shift towards lower/higher wavelength sides. New PL bands observed have been assigned to the transitions related to the impurity states present in the band gap of ZnO along with intrinsic defects.

Panda, N. R.; Acharya, B. S.

2015-01-01

133

Strain-induced partially flat band, helical snake states and interface superconductivity in topological crystalline insulators  

NASA Astrophysics Data System (ADS)

Topological crystalline insulators in IV-VI compounds host novel topological surface states consisting of multi-valley massless Dirac fermions at low energy. Here we show that strain generically acts as an effective gauge field on these Dirac fermions and creates pseudo-Landau orbitals without breaking time-reversal symmetry. We predict the realization of this phenomenon in IV-VI semiconductor heterostructures, due to a naturally occurring misfit dislocation array at the interface that produces a periodically varying strain field. Remarkably, the zero-energy Landau orbitals form a flat band in the vicinity of the Dirac point, and coexist with a network of snake states at higher energy. We propose that the high density of states of this flat band gives rise to interface superconductivity observed in IV-VI semiconductor multilayers at unusually high temperatures, with non-Bardeen-Cooper-Schrieffer behaviour. Our work demonstrates a new route to altering macroscopic electronic properties to achieve a partially flat band, and provides a starting point for realizing novel correlated states of matter.

Tang, Evelyn; Fu, Liang

2014-12-01

134

Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic Strings  

Microsoft Academic Search

We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of $Z = 100$ to the present and calculated the anisotropies which they induce. Based on a limited number of realizations, we have compared the results of

B. Allen; R. R. Caldwell; E. P. S. Shellard; A. Stebbins; S. Veeraraghavan

1994-01-01

135

Radiation-induced coronary artery disease  

SciTech Connect

This report describes three patients who developed myocardial infarction at an untimely age, 4 to 12 years after radiation therapy for Hodgkin's disease. These cases lend credence to the cause and effect relation of such therapy to coronary artery disease.

Dunsmore, L.D.; LoPonte, M.A.; Dunsmore, R.A.

1986-07-01

136

Non-Targeted Bystander Effects Induced by Ionizing Radiation  

SciTech Connect

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

Morgan, William F.; Sowa, Marianne B.

2007-03-01

137

Microscopic Effects of Shock Metamorphism in Crystalline Rocks Correlated With Shock Induced Changes in Density, Haughton Impact Structure  

NASA Astrophysics Data System (ADS)

Asteroid and comet impacts are an important geological process on all solid planetary bodies, including Earth, and involve pressures and temperatures that may reach several hundred GPa and several thousand K [1] over very limited spatial and temporal scales. This results in shock metamorphism and alters the target material on both megascopic and microscopic scales [2]. Many shock metamorphic features are unique to hypervelocity impact environments and are, therefore, diagnostic of such an event [1,2]. Of particular interest for this study is the effect of hypervelocity impact on the density of the target material. In the case of crystalline target rocks, shock metamorphism results in an increase of pore space and impact induced fractures which act to decrease the density. The Haughton impact structure is a well-preserved late Eocene (39 ± 2 Ma) complex impact structure, situated near the western end of Devon Island (75°22'N, 89°41'W) [3]. The geology of the area consists of a sedimentary sequence unconformably overlying crystalline Precambrian gneisses of the Canadian Shield. Since the impact, Devon Island has remained tectonically stable and Haughton remains well-preserved despite being subjected to several glaciations. The excellent preservation of the structure is largely due to the primarily cold and relatively dry environment that has existed in the Arctic since the Eocene [3]. Samples of crystalline material were collected from 36 sites within the impact breccia unit of the Haughton impact structure. These samples display a wide range of density and physical appearance. The type of shock effect(s) created depends upon the pressures and temperatures involved as well as the composition, density and material's location in the target. The samples found in the Haughton impact structure show a wide range of shock effects and thus were exposed to a variety of different conditions likely due to their in-situ positions relative to the impact. Polished thin sections from a representative selection of shocked and unshocked Precambrian gneiss from the Haughton impact structure were investigated in transmitted light with a petrographic microscope and each sample was assigned a shock level based on the identification of shock features. Features identified include kink banding in mica, planar deformation features in quarts and feldspar, and partial or complete melting of various minerals. The density of each sample was also measured. Preliminary results suggest a correlation between decreasing density and increasing shock level. These results may be important not only for understanding shock metamorphism, but also for astrobiology. Impact- induced density decreases in crystalline rocks present opportunities for microbial colonization that would not exist otherwise [4]. The colonization of the shocked material in craters represents a potential mechanism for pioneer organisms to invade an impact structure in the earliest stages of post-impact primary succession. This is a possible mechanism by which microbes may gain a foothold on planetary surfaces that do not have other hospitable habitats. This may be of particular relevance to Mars [4]. [1] Langenhorst, F., Bulletin of the Czech Geo. Survey, 2002. 77, (4): p. 265-282. [2] Therriault, A.M. et al. Bul- letin of the Czech Geo. Survey, 2002. 77, (4): p. 253-263. [3] Stöffler, D. (1971) Journal of Geo-physical Research, 79, (23) [4] Cockell, C.S. et al. Met. & Pl. Sci., 2002. 37, p. 1287-1298.

Singleton, A. C.; Osinski, G.; Moser, D.

2009-05-01

138

Induced radiation processes in single-bubble sonoluminescence  

E-print Network

According to the recent revision of the theory of thermal radiation, thermal black-body radiation has an induced origin. We show that in single-bubble sonoluminescence thermal radiation is emitted by a spherical resonator, coincident with the sonoluminescing bubble itself, instead of the ensemble of elementary resonators emitting thermal black-body radiation in the case of open gaseous media. For a given wavelength, the diameter of the resonator is fixed, and this explains the very high constancy in phase of light flashes from the sonoluminesing bubble, which is better than the constancy of period of a driving acoustic wave.

Prigara, F V

2005-01-01

139

Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy.  

PubMed

Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50 °C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1-5 W/cm(2)). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy. PMID:25391603

Tamarov, Konstantin P; Osminkina, Liubov A; Zinovyev, Sergey V; Maximova, Ksenia A; Kargina, Julia V; Gongalsky, Maxim B; Ryabchikov, Yury; Al-Kattan, Ahmed; Sviridov, Andrey P; Sentis, Marc; Ivanov, Andrey V; Nikiforov, Vladimir N; Kabashin, Andrei V; Timoshenko, Victor Yu

2014-01-01

140

Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy  

NASA Astrophysics Data System (ADS)

Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50°C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1-5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

Tamarov, Konstantin P.; Osminkina, Liubov A.; Zinovyev, Sergey V.; Maximova, Ksenia A.; Kargina, Julia V.; Gongalsky, Maxim B.; Ryabchikov, Yury; Al-Kattan, Ahmed; Sviridov, Andrey P.; Sentis, Marc; Ivanov, Andrey V.; Nikiforov, Vladimir N.; Kabashin, Andrei V.; Timoshenko, Victor Yu

2014-11-01

141

Electromagnetically Induced Transparency using six level atoms doped in the crystalline medium  

E-print Network

Using the density matrix theory of interaction between light and matter, and relevant parameters of the relaxation rates for a six-level model, we have shown theoretically the possibility of realizing Electromagnetically Induced Transparency (EIT) and Slow Light effects in Pr(+3 ion) doped YSO crystal. In addition, we have presented a simplified method to analyse EIT effect in such a six level atomic system. Finally, we have demonstrated results of numerical calculation and have compared them with experimental measurements reported recently.

Hassan Kaatuzian; Sina Mehrabadi; Ahmad Ajdarzadeh Oskouei

2005-11-22

142

Correlation between stimulated scattering processes and laser-induced damage in crystalline quartz  

NASA Technical Reports Server (NTRS)

The results of a systematic series of experiments to uncover possible correlation between laser-induced stimulated-Brillouin-scattering (SBS) phonons and damage in quartz are presented. Such correlation is confirmed and the various thresholds are established. The anomalous transmission factor under phonon generation is found to decay exponentially as predicted with increasing incident laser power. The LF SBS phonon is also demonstrated to be a sensitive probe for precatastrophic damage.

Yu, C.; Haw, M. F.; Hsu, H.

1977-01-01

143

Radioprotectors and Mitigators of Radiation-Induced Normal Tissue Injury  

PubMed Central

Radiation is used in the treatment of a broad range of malignancies. Exposure of normal tissue to radiation may result in both acute and chronic toxicities that can result in an inability to deliver the intended therapy, a range of symptoms, and a decrease in quality of life. Radioprotectors are compounds that are designed to reduce the damage in normal tissues caused by radiation. These compounds are often antioxidants and must be present before or at the time of radiation for effectiveness. Other agents, termed mitigators, may be used to minimize toxicity even after radiation has been delivered. Herein, we review agents in clinical use or in development as radioprotectors and mitigators of radiation-induced normal tissue injury. Few agents are approved for clinical use, but many new compounds show promising results in preclinical testing. PMID:20413641

Cotrim, Ana P.; Hyodo, Fuminori; Baum, Bruce J.; Krishna, Murali C.; Mitchell, James B.

2010-01-01

144

Radiation-Induced Heart Disease: Pathologic Abnormalities and Putative Mechanisms  

PubMed Central

Breast cancer is a common diagnosis in women. Breast radiation has become critical in managing patients who receive breast conserving surgery, or have certain high-risk features after mastectomy. Most patients have an excellent prognosis, therefore understanding the late effects of radiation to the chest is important. Radiation-induced heart disease (RIHD) comprises a spectrum of cardiac pathology including myocardial fibrosis and cardiomyopathy, coronary artery disease, valvular disease, pericardial disease, and arrhythmias. Tissue fibrosis is a common mediator in RIHD. Multiple pathways converge with both acute and chronic cellular, molecular, and genetic changes to result in fibrosis. In this article, we review the pathophysiology of cardiac disease related to radiation therapy to the chest. Our understanding of these mechanisms has improved substantially, but much work remains to further refine radiation delivery techniques and develop therapeutics to battle late effects of radiation. PMID:25741474

Taunk, Neil K.; Haffty, Bruce G.; Kostis, John B.; Goyal, Sharad

2015-01-01

145

Role of PPARs in Radiation-Induced Brain Injury  

PubMed Central

Whole-brain irradiation (WBI) represents the primary mode of treatment for brain metastases; about 200 000 patients receive WBI each year in the USA. Up to 50% of adult and 100% of pediatric brain cancer patients who survive >6 months post-WBI will suffer from a progressive, cognitive impairment. At present, there are no proven long-term treatments or preventive strategies for this significant radiation-induced late effect. Recent studies suggest that the pathogenesis of radiation-induced brain injury involves WBI-mediated increases in oxidative stress and/or inflammatory responses in the brain. Therefore, anti-inflammatory strategies can be employed to modulate radiation-induced brain injury. Peroxisomal proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the steroid/thyroid hormone nuclear receptor superfamily. Although traditionally known to play a role in metabolism, increasing evidence suggests a role for PPARs in regulating the response to inflammation and oxidative injury. PPAR agonists have been shown to cross the blood-brain barrier and confer neuroprotection in animal models of CNS disorders such as stroke, multiple sclerosis and Parkinson's disease. However, the role of PPARs in radiation-induced brain injury is unclear. In this manuscript, we review the current knowledge and the emerging insights about the role of PPARs in modulating radiation-induced brain injury. PMID:19789638

Ramanan, Sriram; Zhao, Weiling; Riddle, David R.; Robbins, Mike E.

2010-01-01

146

Radiation induced electron traps in silicon dioxide  

Microsoft Academic Search

Trapping of electrons injected from an avalanche generated in the silicon substrate, into a thermally grown silicon dioxide film was used to investigate the effect of penetrating radiation (x rays; Cu target) on the electron transport properties of the oxide. Experiments with samples of different SiO2 thicknesses indicate that two sets of neutral centers are generated by the x rays

W. Schmitz; D. R. Young

1983-01-01

147

Annealing induced variation of crystalline structure and mechanical properties of syndiotactic polypropylene fibers  

Microsoft Academic Search

Syndiotactic polypropylene (sPP) as-spun fiber (sPP1) and drawn fiber (sPP2) were prepared by melt-spinning and melt-spinning\\/hot-drawing, respectively. The structure transition of the two fibers\\u000a induced by annealing at different temperatures and the corresponding mechanical properties were subsequently investigated\\u000a by the combination of Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD) and tensile testing.\\u000a The results indicate that the chain

Xiu-qin Zhang; Bao-quan Xie; Rong-bo Li; Lei Kong; Du-jin Wang

2010-01-01

148

Thermal cycling induced load on copper-ribbons in crystalline photovoltaic modules  

NASA Astrophysics Data System (ADS)

Solar module lifetime is limited by the fatigue behavior of its cell interconnectors: the copper-ribbons. Every change in temperature induces thermo-mechanical stresses in the module components due to their thermo-mechanical mismatch. The purpose of this work is to quantify this load on the copper-ribbons between the individual cells of a cell string during a thermal cycling test by measuring cell displacement using digital image correlation and to compare the results to finite element analysis (FEM). Furthermore with help of FEM the influences of different materials were investigated, allowing material and layout optimizations with respect to copper-ribbon loading.

Meier, R.; Kraemer, F.; Wiese, S.; Wolter, K.-J.; Bagdahn, J.

2010-08-01

149

Electromechanical actuation and current-induced metastable states in suspended single-crystalline VO2 nanoplatelets  

SciTech Connect

Current-induced electromechanical actuation enabled by the metal-insulator transition in VO{sub 2} nanoplatelets is demonstrated. The Joule heating by a sufficient current flowing through suspended nanoplatelets results in formation of heterophase domain patterns and is accompanied by nanoplatelet deformation. The actuation action can be achieved in a wide temperature range below the bulk phase transition temperature (68 C). The observed current-sustained heterophase domain structures should be interpreted as distinct metastable states in free-standing and end-clamped VO{sub 2} samples. We analyze the main prerequisites for the realization of a current-controlled actuator based on the proposed concept.

Tselev, Alexander [ORNL; Budai, John D [ORNL; Strelcov, Evgheni [Southern Illinois University; Tischler, Jonathan Zachary [ORNL; Kolmakov, Andrei [Southern Illinois University; Kalinin, Sergei V [ORNL

2011-01-01

150

Radiation-induced biomarkers for the detection and assessment of absorbed radiation doses  

PubMed Central

Radiation incident involving living organisms is an uncommon but a very serious situation. The first step in medical management including triage is high-throughput assessment of the radiation dose received. Radiation exposure levels can be assessed from viability of cells, cellular organelles such as chromosome and different intermediate metabolites. Oxidative damages by ionizing radiation result in carcinogenesis, lowering of the immune response and, ultimately, damage to the hematopoietic system, gastrointestinal system and central nervous system. Biodosimetry is based on the measurement of the radiation-induced changes, which can correlate them with the absorbed dose. Radiation biomarkers such as chromosome aberration are most widely used. Serum enzymes such as serum amylase and diamine oxidase are the most promising biodosimeters. The level of gene expression and protein are also good biomarkers of radiation. PMID:21829314

Rana, Sudha; Kumar, Raj; Sultana, Sarwat; Sharma, Rakesh Kumar

2010-01-01

151

Modulation of Radiation-Induced Apoptosis by Thiolamines  

NASA Technical Reports Server (NTRS)

Exposure to the thiolamine radioprotector N-(2-mercaptoethyl)-1,3-propanediamine (WR-1065) induced apoptosis in the mouse TB8-3 hybridoma after 60-minute (LD(sub50) = 4.5mM) or during a 20-hour (LD(sub50) = 0.15 mM) exposure. In contrast, a 20-hour exposure to 17 mM L-cysteine or 10 mM cysteamine was required to induce 50 percent apoptosis within 20 hours. Apoptosis was not induced by either a 60-minute or 20-hour exposure to 10 mM of the thiazolidime prodrugs ribose-cysteine (RibCys) or ribose-cysteamine (RibCyst). Thiolamine-induced apoptosis appeared to be a p53-independent process since it was induced by WR-1065 exposure in human HL60 cells. Exposure to WR-1065 (4mM for 15 minutes) or cysteine (10mM for 60 minutes) before and during irradiation protected cells against the induction of both DNA double-strand breaks and apoptosis, while exposure to RibCys (10 mM for 3 hours) did not. Treatment with either WR-1065, cysteine, RibCys or RibCyst for 60 minutes beginning 60 minutes after irradiation did not affect the level of radiation-induced apoptosis. In contrast, treatment with either cysteine, cysteamine or RibCys for 20 hours beginning 60 minutes after irradiation enhanced radiation-induced apoptosis. Similar experiments could not be conducted with WR-1065 because of its extreme toxicity. Our results indicate that thiolamine enhancement of radiation-induced apoptosis is not involved in their previously reported capacity to reduce radiation-induced mutations.

Warters, R. L.; Roberts, J. C.; Wilmore, B. H.; Kelley, L. L.

1997-01-01

152

Radiation-Induced Bystander Effects in Cultured Human Stem Cells  

Microsoft Academic Search

BackgroundThe radiation-induced “bystander effect” (RIBE) was shown to occur in a number of experimental systems both in vitro and in vivo as a result of exposure to ionizing radiation (IR). RIBE manifests itself by intercellular communication from irradiated cells to non-irradiated cells which may cause DNA damage and eventual death in these bystander cells. It is known that human stem

Mykyta V. Sokolov; Ronald D. Neumann; Henning Ulrich

2010-01-01

153

Radiation-induced bystander effects, carcinogenesis and models  

Microsoft Academic Search

Implications for carcinogenesis of radiation-induced bystander effects are both mechanistic and practical. They include induction of second cancers, perturbations to tissue social control and induction of genomic instability and delayed or immediate mutations in areas not receiving a direct deposition of energy. Bystander effects have consequences for DNA damage-mutation-cancer initiation paradigms of radiation carcinogenesis that provide the mechanistic justification for

Carmel Mothersill; Colin Seymour

2003-01-01

154

Radiation-induced space-charge buildup in MOS structures  

Microsoft Academic Search

An analysis of a simple model for radiation-induced space-charge buildup in the SiO2layers of MOS structures has been carried out. The model assumes that hole-electron pairs are created in the SiO2by the radiation and that some of the electrons thus created drift out of the SiO2layer under the action of an applied potential across the oxide, VG, while the corresponding

J. P. Mitchell

1967-01-01

155

Mitigation of radiation induced surface contamination  

SciTech Connect

A process for mitigating or eliminating contamination and/or degradation of surfaces having common, adventitious atmospheric contaminants adsorbed thereon and exposed to radiation. A gas or a mixture of gases is introduced into the environment of a surface(s) to be protected. The choice of the gaseous species to be introduced (typically a hydrocarbon gas, water vapor, or oxygen or mixtures thereof) is dependent upon the contaminant as well as the ability of the gaseous species to bind to the surface to be protected. When the surface and associated bound species are exposed to radiation reactive species are formed that react with surface contaminants such as carbon or oxide films to form volatile products (e.g., CO, CO.sub.2) which desorb from the surface.

Klebanoff, Leonard E. (Dublin, CA); Stulen, Richard H. (Livermore, CA)

2003-01-01

156

Chemotherapy or radiation-induced oral mucositis.  

PubMed

Oral mucositis is a significant toxicity of systemic chemotherapy and of radiation therapy to the head and neck region. The morbidity of oral mucositis can include pain, nutritional compromise, impact on quality of life, alteration in cancer therapy, risk for infection, and economic costs. Management includes general symptomatic support and targeted therapeutic interventions for the prevention or treatment of oral mucositis. Evidence-based clinical practice guidelines are available to guide clinicians in the selection of effective management strategies. PMID:24655526

Lalla, Rajesh V; Saunders, Deborah P; Peterson, Douglas E

2014-04-01

157

Ionizing Radiation Induces Delayed Hyperrecombination in Mammalian Cells  

PubMed Central

Exposure to ionizing radiation can result in delayed effects that can be detected in the progeny of an irradiated cell multiple generations after the initial exposure. These effects are described under the rubric of radiation-induced genomic instability and encompass multiple genotoxic endpoints. We have developed a green fluorescence protein (GFP)-based assay and demonstrated that ionizing radiation induces genomic instability in human RKO-derived cells and in human hamster hybrid GM10115 cells, manifested as increased homologous recombination (HR). Up to 10% of cells cultured after irradiation produce mixed GFP+/? colonies indicative of delayed HR or, in the case of RKO-derived cells, mutation and deletion. Consistent with prior studies, delayed chromosomal instability correlated with delayed reproductive cell death. In contrast, cells displaying delayed HR showed no evidence of delayed reproductive cell death, and there was no correlation between delayed chromosomal instability and delayed HR, indicating that these forms of genome instability arise by distinct mechanisms. Because delayed hyperrecombination can be induced at doses of ionizing radiation that are not associated with significantly reduced cell viability, these data may have important implications for assessment of radiation risk and understanding the mechanisms of radiation carcinogenesis. PMID:15143196

Huang, Lei; Grim, Suzanne; Smith, Leslie E.; Kim, Perry M.; Nickoloff, Jac A.; Goloubeva, Olga G.; Morgan, William F.

2004-01-01

158

Inhibition of radiation-induced polyuria by histamine receptor antagonists  

SciTech Connect

In previous studies the authors have demonstrated that gamma radiation results in polyuria, which is preceded by polydypsia. This suggests that the increased thirst elicited by radiation causes increased urinary volume (UV). Histamine, which is released following radiation exposure, also elicits drinking by nonirradiated rats when administered exogenously. In this study the authors have investigated both the role of water deprivation and the effect of histamine receptor antagonists (HRA) on radiation-induced polyuria. Sprague-Dawley rats were housed individually in metabolic cages. Water was allowed ad libitum except in deprivation experiments where water was removed for 24 hr immediately following radiation. Cimetidine (CIM), an H2 HRA, and dexbromopheniramine (DXB), an H1 HRA, were administered i.p. (16 and 1 mg/kg, respectively) 30 min prior to irradiation (950 rads from a cobalt source). UV was determined at 24-hr intervals for 3 days preceding irradiation and 24 hr postirradiation. UV in DXB treated rats was significantly reduced 24 hr postirradiation (CON = 427 +/- 54%; DXB = 247 +/- 39% of preirradiated CON) compared to postirradiation control values. CIM did not affect postirradiation UV. These data suggest that radiation-induced polyuria is caused by polydypsia which is, in part, mediated by histamine induced by an H1 receptor.

Donlon, M.A.; Melia, J.A.; Helgeson, E.A.; Wolfe, W.W.

1986-03-01

159

The Mechanisms of Radiation-Induced Bystander Effect  

PubMed Central

The radiation-induced bystander effect is the phenomenon which non-irradiated cells exhibit effects along with their different levels as a result of signals received from nearby irradiated cells. Responses of non-irradiated cells may include changes in process of translation, gene expression, cell proliferation, apoptosis and cells death. These changes are confirmed by results of some In-Vivo studies. Most well-known important factors affecting radiation-induced bystander effect include free radicals, immune system factors, expression changes of some genes involved in inflammation pathway and epigenetic factors. PMID:25599062

Najafi, M; Fardid, R; Hadadi, Gh; Fardid, M

2014-01-01

160

Panretinal photocoagulation for radiation-induced ocular ischemia  

SciTech Connect

We present preliminary findings on the effectiveness of panretinal photocoagulation in preventing neovascular glaucoma in eyes with radiation-induced ocular ischemia. Our study group consisted of 20 patients who developed radiation-induced ocular ischemia following cobalt-60 plaque radiotherapy for a choroidal or ciliary body melanoma. Eleven of the 20 patients were treated by panretinal photocoagulation shortly after the diagnosis of ocular ischemia, but nine patients were left untreated. In this non-randomized study, the rate of development of neovascular glaucoma was significantly lower (p = 0.024) for the 11 photocoagulated patients than for the nine who were left untreated.

Augsburger, J.J.; Roth, S.E.; Magargal, L.E.; Shields, J.A.

1987-08-01

161

[Symptoms, diagnosis and treatment of radiation-induced enteritis].  

PubMed

The number of radiotherapy in the treatment of malignant diseases is increasing worldwide. During the radiotherapy of tumors in the minor pelvis and abdomen intestinal inflammation of different degree may occur even if special attention is paid. Irradiation to the minor pelvis causes in half of the cases radiation induced acute enteritis, whereas in 25% chronic enteritis and colitis will develop. Chronic enteritis following radiotherapy raises a number of diagnostic and therapeutic problems that can be solved only with cooperation of different specialties. Authors present a short review regarding therapeutical options of radiation induced enteritis. PMID:20739262

Sinkó, Dániel; Baranyai, Zsolt; Nemeskéri, Csaba; Teknos, Dániel; Jósa, Valéria; Hegedus, László; Mayer, Arpád

2010-09-01

162

The mechanisms of radiation-induced bystander effect.  

PubMed

The radiation-induced bystander effect is the phenomenon which non-irradiated cells exhibit effects along with their different levels as a result of signals received from nearby irradiated cells. Responses of non-irradiated cells may include changes in process of translation, gene expression, cell proliferation, apoptosis and cells death. These changes are confirmed by results of some In-Vivo studies. Most well-known important factors affecting radiation-induced bystander effect include free radicals, immune system factors, expression changes of some genes involved in inflammation pathway and epigenetic factors. PMID:25599062

Najafi, M; Fardid, R; Hadadi, Gh; Fardid, M

2014-12-01

163

Exaggerated radiation-induced fibrosis in patients with systemic sclerosis  

SciTech Connect

Four patients with stable systemic sclerosis and limited skin involvement received radiation for the treatment of solid malignant neoplasms. Following localized irradiation, each patient developed an exaggerated cutaneous and internal fibrotic reaction in the irradiated areas. The surface area of fibrosis extended beyond the radiation portals employed, and the fibrotic process was poorly responsive to antifibrotic therapy. Three of the patients died of complications caused by fibrous encasement of internal organs. The extent and severity of postradiation fibrosis in these patients was distinctly unusual. These observations suggest that patients with systemic sclerosis are particularly susceptible to developing excessive radiation-induced fibrosis.

Varga, J.; Haustein, U.F.; Creech, R.H.; Dwyer, J.P.; Jimenez, S.A. (Department of Medicine, Jefferson Medical College, Philadelphia, PA (USA))

1991-06-26

164

Factors that modify risks of radiation-induced cancer.  

PubMed

The collective influence of biologic, physical, and other factors that modify risks of radiation-induced cancer introduces uncertainties and assumptions that limit precision of estimates of human cancer risk that can be calculated for populations exposed to low-dose radiation. The important biologic characteristics include the tissue sites and cell types, baseline cancer incidence, latent periods, time-to-tumor recognition, and individual host (e.g., age and sex) and competing etiologic influences. Physical factors include radiation dose, dose rate, and radiation quality. Statistical factors include time-response projection models, risk coefficients, and dose-response relationships. Sources that modify risk also include other carcinogens and biologic factors (e.g., hormonal conditions, immune status, hereditary factors). Discussion includes examples of known influences that modify radiation-associated cancer risks and how they have been dealt with in the risk-estimation process, including extrapolation to low doses, use of relative risk models, and other uncertainties. PMID:2358362

Fabrikant, J I

1990-07-01

165

Mechanisms of radiation-induced neoplastic cell transformation  

SciTech Connect

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

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

1984-04-01

166

Effective surface passivation of p-type crystalline silicon with silicon oxides formed by light-induced anodisation  

NASA Astrophysics Data System (ADS)

Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO2) was investigated. The anodic SiO2 was grown by light-induced anodisation (LIA) in diluted sulphuric acid at room temperature, a process that is significantly less-expensive than thermal oxidation which is widely-used in silicon solar cell fabrication. After annealing in oxygen and then forming gas at 400 °C for 30 min, the effective minority carrier lifetime of 3-5 ? cm, boron-doped Czochralski silicon wafers with a phosphorus-doped 80 ?/? emitter and a LIA anodic SiO2 formed on the p-type surface was increased by two orders of magnitude to 150 ?s. Capacitance-voltage measurements demonstrated a very low positive charge density of 3.4 × 1011 cm-2 and a moderate density of interface states of 6 × 1011 eV-1 cm-2. This corresponded to a silicon surface recombination velocity of 62 cm s-1, which is comparable with values reported for other anodic SiO2 films, which required higher temperatures and longer growth times, and significantly lower than oxides grown by chemical vapour deposition techniques. Additionally, a very low leakage current density of 3.5 × 10-10 and 1.6 × 10-9 A cm-2 at 1 and -1 V, respectively, was measured for LIA SiO2 suggesting its potential application as insulation layer in IBC solar cells and a barrier for potential induced degradation.

Cui, Jie; Grant, Nicholas; Lennon, Alison

2014-12-01

167

Pressure- and temperature-induced transformations in crystalline polymers of C{sub 60}  

SciTech Connect

The great advantage of the C{sub 60} molecule is its potential for polymerization, due to which the molecule can be the building block of new all carbon materials. In addition, it contains, both sp{sup 2} and sp{sup 3} hybridized carbon atoms, which allows synthesizing new carbon materials with desired physicochemical properties using both types of carbon bonding. The one- and two-dimensional polymeric phases of C{sub 60} are prototype materials of this sort. Their properties, especially polymerization under pressure and room temperature via covalent bonding between molecules belonging to adjacent polymeric chains or polymeric layers, can be used for further development of new materials. The present review focuses on the study of the pressure-induced polymerization and thermodynamic stability of these materials and their recovered new phases by in-situ high-pressure Raman and X-ray diffraction studies. The phonon spectra show that the fullerene molecular cage in the high-pressure phases is preserved, while these polymers decompose under heat treatment into the initial fullerene C{sub 60} monomer.

Meletov, K. P., E-mail: mele@issp.ac.ru [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation); Kourouklis, G. A. [Aristotle University of Thessaloniki GR-54006, Physics Division, School of Technology (Greece)

2012-10-15

168

Radiation induced leakage current and stress induced leakage current in ultra-thin gate oxides  

Microsoft Academic Search

Low-field leakage current has been measured in thin oxides after exposure to ionising radiation. This Radiation Induced Leakage Current (RILC) can be described as an inelastic tunnelling process mediated by neutral traps in the oxide, with an energy loss of about 1 eV. The neutral trap distribution is influenced by the oxide field applied during irradiation, thus indicating that the

M. Ceschia; A. Paccagnella; A. Cester; A. Scarpa; G. Ghidini

1998-01-01

169

Chemoprevention of Radiation Induced Rat Mammary Neoplasms  

NASA Technical Reports Server (NTRS)

Radiations encountered in space include protons and heavy ions such as iron as well as their secondaries. The relative biological effect (RBE) of these ions is not known, particularly at the doses and dose-rates expected for planetary missions. Neutrons, are not particularly relevant to space travel, but have been found experimentally to have an increase in their RBE with decreasing dose. If a similar trend of increasing RBE with decreasing dose is present for heavy ions and protons during irradiation in space, the small doses received during space travel could potentially have substantial carcinogenic risk. Clearly more investigation of the effects of heavy ions and protons is needed before accurate risk assessment for prolonged travel in space can be done. One means to mitigate the increased risk of cancer due to radiation exposure in space is by developing effective countermeasures that can reduce the incidence of tumor development. Tamoxifen has recently been shown to be an effective chemopreventive agent in both animal models and humans for the prevention of mammary tumors. Tamoxifen is a unique drug, with a highly specific mechanism of action affecting a specific radiation-sensitive population of epithelial cells in the mammary gland. In human studies, the annual incidence of a primary tumor in the contralateral breast of women with previous breast cancer is about 8 per 1000, making them an exceedingly high-risk group for the development of breast cancer. In this high risk group, treated with tamoxifen, daily, for 2 years, the incidence of a new primary tumor in the contralateral breast was approximately one third of that noted in the non-tamoxifen treatment group. Tamoxifen antagonizes the action of estrogen by competing for the nuclear receptor complex thereby altering the association of the receptor complex and nuclear binding sites. Its effects in reducing the development of breast cancer could be accomplished by controlling clinically undetectable microcancers, arresting preneoplastic lesions, or correcting abnormal environments which predispose to high risk of malignant transformation.

Huso, David L.

1999-01-01

170

Radiation-induced endometriosis in Macaca mulatta  

SciTech Connect

Female rhesus monkeys received whole-body doses of ionizing radiation in the form of single-energy protons, mixed-energy protons, X rays, and electrons. Endometriosis developed in 53% of the monkeys during a 17-year period after exposure. Incidence rates for endometriosis related to radiation type were: single-energy protons, 54%; mixed-energy protons, 73%; X rays, 71%; and electrons, 57%. The incidence of endometriosis in nonirradiated control monkeys was 26%. Monkeys exposed to single-energy protons, mixed-energy protons, and X rays developed endometriosis at a significantly higher rate than control monkeys (chi 2, P less than 0.05). Severity of endometriosis was staged as massive, moderate, and minimal. The incidence of these stages were 65, 16, and 19%, respectively. Observations of clinical disease included weight loss in 43% of the monkeys, anorexia in 35%, space-occupying masses detected by abdominal palpation in 55%, abnormal ovarian/uterine anatomy on rectal examination in 89%, and radiographic evidence of abdominal masses in 38%. Pathological lesions were endometrial cyst formation in 69% of the monkeys, adhesions of the colon in 66%, urinary bladder in 50%, ovaries in 86%, and ureters in 44%, focal nodules of endometrial tissue throughout the omentum in 59%, and metastasis in 9%. Clinical management of endometriosis consisted of debulking surgery and bilateral salpingo-oophorectomy combined in some cases with total abdominal hysterectomy. Postoperative survival rates at 1 and 5 years for monkeys recovering from surgery were 48 and 36%, respectively.

Fanton, J.W.; Golden, J.G. (USAF School of Aerospace Medicine, Brooks AFB, TX (USA))

1991-05-01

171

Stimulation of respiration in rat thymocytes induced by ionizing radiation  

SciTech Connect

The effect of X irradiation on the respiration of rat thymocytes was studied. An increase in the rate of O[sub 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[sup 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.

Gudz, T.I.; Pandelova, I.G.; Novgorodov, S.A. (Moscow State Univ. (Russian Federation))

1994-04-01

172

SPHINX Measurements of Radiation Induced Conductivity of Foam  

SciTech Connect

Experiments on the SPHINX accelerator studying radiation-induced conductivity (RIC) in foam indicate that a field-exclusion boundary layer model better describes foam than a Maxwell-Garnett model that treats the conducting gas bubbles in the foam as modifying the dielectric constant. In both cases, wall attachment effects could be important but were neglected.

Ballard, W.P.; Beutler, D.E.; Burt, M.; Dudley, K.J.; Stringer, T.A.

1998-12-14

173

SENSITIVITY TO RADIATION-INDUCED CANCER IN HEMOCHROMATOSIS  

EPA Science Inventory

Determination of dose-response relationships for radiation-induced cancer in segments of the population with high susceptibility is critical for understanding the risks of low dose and low dose rates to humans. Clean-up levels for radionuclides will depend upon the fraction of t...

174

Laser therapy for severe radiation-induced rectal bleeding  

SciTech Connect

Four patients with chronic hematochezia and transfusion-dependent anemia from postradiation rectal vascular lesions were successfully managed by endoscopic laser coagulation. In all four patients, symptomatic, hematologic, and endoscopic improvement was evident. Laser therapy for severe radiation-induced rectal bleeding seems to be safe and efficacious and should be considered before surgical intervention.

Ahlquist, D.A.; Gostout, C.J.; Viggiano, T.R.; Pemberton, J.H.

1986-12-01

175

Poor outcome in radiation-induced constrictive pericarditis  

SciTech Connect

The purpose was to compare the outcome of patients with radiation-induced constrictive pericarditis versus patients with constiction due to another etiology. Twenty patients with constrictive pericarditis were seen during 1975-1986 at a single medical center. Six had radiation-induced constrictive pericarditis (Group A). The etiology was idiopathic in ten subjects and secondary to carcinomatous encasement, chronic renal failure, purulent infection and tuberculosis in one patient each (Group B, N = 14). Meang age was 53.4 [+-] 15.5 years. Extensive pericardiectomy was performed in 3/6 Group A and 13/14 Group B patients. All Group A patients died, 4 weeks - 11 years post-diagnosis (median = 10 months). Two Group A patients died suddenly, one died post-operatively of respiratory failure, another of pneumonia and two of recurrent carcinoma. Thirteen Group B patients are alive (median follow-up = 72 months). The only death in this group was due to metastatic cancer. The poor outcome with radiation-induced constriction is probably multi-factorial. Poor surgical outcome is to be expected in patients with evidence of recurrent tumor, high-dose irradiation, pulmonary fibrosis or associated radiation-induced myocardinal, valvular or coronary damage.

Karram, T.; Rinkevitch, D.; Markiewicz, W. (Technion Medical School, Haifa (Israel))

1993-01-15

176

Gamma Radiation Induced Calibration Shift for Four Cryogenic Thermometer Types  

NASA Astrophysics Data System (ADS)

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

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

2004-06-01

177

Radiation-induced mutagenicity and lethality in Salmonella typhimurium  

SciTech Connect

The mutagenic and lethal effects of ionizing radiation on histidine-deficient auxotrophs of Salmonella typhimurium were studied to improve the understanding of radiation damage to DNA. The auxotrophs were divided into two groups - one which is sensitive to base-pair substitutions and another sensitive to frameshifts. These groups were composed of parent-daughter pairs in which the chemical mutagenicity enhancing plasmid, pKM101, is absent in the parent strain and present in the daughter. Co-60 ..gamma..-radiation and 250 kV x-rays were used to irradiate the bacteria. Irradiation of the frameshift - sensitive strains which carry the pKm101 plasmid doubled the absolute number of induced revertants whereas irradiation of the base-pair substitution sensitive strain which also carries the pKm101 plasmid produced nearly no change in the number of induced revertants. A nearly negligible effect on the mutation rate was observed for all parent strains. (ACR)

Isildar, M.; Bakale, G.

1983-01-01

178

Stress-Induced Lift-Off Method for kerf-loss-free wafering of ultra-thin (?50 ?m) crystalline Si wafers  

Microsoft Academic Search

We present a new wafering method for the production of ultra-thin crystalline silicon. This new lift-off process, named SLIM-cut (for Stress-induced LIft-off Method), requires only the use of a screen-printer and a belt furnace; no ion-implanted, porous layer or additional thickening by epitaxy is needed to obtain high quality wafers in the thickness range of 50 ?m without kerf loss.

Frederic Dross; Aurelien Milhe; Jo Robbelein; Ivan Gordon; Pierre-Olivier Bouchard; Guy Beaucarne; Jef Poortmans

2008-01-01

179

Radiation-induced genomic instability and its implications for radiation carcinogenesis  

NASA Technical Reports Server (NTRS)

Radiation-induced genomic instability is characterized by an increased rate of genetic alterations including cytogenetic rearrangements, mutations, gene amplifications, transformation and cell death in the progeny of irradiated cells multiple generations after the initial insult. Chromosomal rearrangements are the best-characterized end point of radiation-induced genomic instability, and many of the rearrangements described are similar to those found in human cancers. Chromosome breakage syndromes are defined by chromosome instability, and individuals with these diseases are cancer prone. Consequently, chromosomal instability as a phenotype may underlie some fraction of those changes leading to cancer. Here we attempt to relate current knowledge regarding radiation-induced chromosome instability with the emerging molecular information on the chromosome breakage syndromes. The goal is to understand how genetic and epigenetic factors might influence the onset of chromosome instability and the role of chromosomal instability in carcinogenesis.

Huang, Lei; Snyder, Andrew R.; Morgan, William F.

2003-01-01

180

Radiation-induced dural fibrosarcoma with unusually short latent period  

SciTech Connect

Although rare, the occurrence of radiation-induced intracranial neoplasms of various types is well known. Among these tumors, fibrosarcomas, especially in the region of seila turcica, seem to be the most common type. These tumors characteristically occur after a long latent period, usually several years, following radiation therapy. The authors now report a case of apparently radiation-induced fibrosarcoma with some unusual features in a 10-year-old boy who was treated with radiation for medulloblastoma. He received a total dose of 53.2 Gy radiation delivered at 1.8 per fraction with 6 MV acceleration using the standard craniospinal technique. An MRI at 15 months after the completion of radiotherapy showed a mass over the cerebral convexity, which increased two-fold in size within a period of 4 months. A well circumscribed tumor was removed from the fronto-parietal convexity. The tumor measured 5x4.5x1.5 cm and was attached to the dura with invasion of the overlying bone. Histologically, it displayed the characteristic features of a low-grade fibrosarcoma. The patient remains free of tumor 18 months after the surgery. This case emphasizes the potential risk for the development of a second neoplasm following therapeutic radiation and also documents, to the authors' knowledge, the shortest latent period reported so far between administration of radiotherapy and development of an intracranial tumor.

Ghatak, N.R.; Aydin, F.; Leshner, R.T. (Medical College of Virginia, Richmond (United States) Tulane Univ., New Orleans, LA (United States))

1993-05-01

181

Factors that modify risks of radiation-induced cancer  

SciTech Connect

The collective influence of biologic and physical factors that modify risks of radiation-induced cancer introduces uncertainties sufficient to deny precision of estimates of human cancer risk that can be calculated for low-dose radiation in exposed populations. The important biologic characteristics include the tissue sites and cell types, baseline cancer incidence, minimum latent period, time-to-tumor recognition, and the influence of individual host (age and sex) and competing etiologic influences. Physical factors include radiation dose, dose rate, and radiation quality. Statistical factors include time-response projection models, risk coefficients, and dose-response relationships. Other modifying factors include other carcinogens, and other biological sources (hormonal status, immune status, hereditary factors).

Fabrikant, J.I.

1988-11-01

182

Pulsed radiation-induced attenuation in certain optical fibers  

SciTech Connect

Using the X-ray pulse from the HERMES II simulation machine at Sandia National Laboratories, the pulsed radiation-induced attenuation was measured in two optical fibers considered to be 'nonrad-hard': the 50-micron-core, graded-index fiber from Corning and the plastic (PMMA) fiber from the Mitsubishi Rayon Company. These fibers were exposed to radiation up to doses of 19.5 and 28 krad(Si), respectively. In addition, fits of their post-radiation recovery were made to the geminate recombination model, from which the recombination-rate and generation constants, characteristic of this theory, were determined. These parameters should be useful in determining the response of the fibers to radiation conditions other than those encountered here. 18 refs.

Weiss, J.D. (Sandia National Laboratories, Albuquerque, NM (United States))

1992-05-01

183

The Dose Window for Radiation-Induced Protective Adaptive Responses  

PubMed Central

Adaptive responses to low doses of low LET radiation occur in all organisms thus far examined, from single cell lower eukaryotes to mammals. These responses reduce the deleterious consequences of DNA damaging events, including radiation-induced or spontaneous cancer and non-cancer diseases in mice. The adaptive response in mammalian cells and mammals operates within a certain window that can be defined by upper and lower dose thresholds, typically between about 1 and 100 mGy for a single low dose rate exposure. However, these thresholds for protection are not a fixed function of total dose, but also vary with dose rate, additional radiation or non-radiation stressors, tissue type and p53 functional status. Exposures above the upper threshold are generally detrimental, while exposures below the lower threshold may or may not increase either cancer or non-cancer disease risk. PMID:20585438

Mitchel, Ronald E. J.

2009-01-01

184

The dose window for radiation-induced protective adaptive responses.  

PubMed

Adaptive responses to low doses of low LET radiation occur in all organisms thus far examined, from single cell lower eukaryotes to mammals. These responses reduce the deleterious consequences of DNA damaging events, including radiation-induced or spontaneous cancer and non-cancer diseases in mice. The adaptive response in mammalian cells and mammals operates within a certain window that can be defined by upper and lower dose thresholds, typically between about 1 and 100 mGy for a single low dose rate exposure. However, these thresholds for protection are not a fixed function of total dose, but also vary with dose rate, additional radiation or non-radiation stressors, tissue type and p53 functional status. Exposures above the upper threshold are generally detrimental, while exposures below the lower threshold may or may not increase either cancer or non-cancer disease risk. PMID:20585438

Mitchel, Ronald E J

2010-01-01

185

Radiation-induced DNA damage and chromatin structure  

NASA Technical Reports Server (NTRS)

DNA lesions induced by ionizing radiation in cells are clustered and not randomly distributed. For low linear energy transfer (LET) radiation this clustering occurs mainly on the small scales of DNA molecules and nucleosomes. For example, experimental evidence suggests that both strands of DNA on the nucleosomal surface can be damaged in single events and that this damage occurs with a 10-bp modulation because of protection by histones. For high LET radiation, clustering also occurs on a larger scale and depends on chromatin organization. A particularly significant clustering occurs when an ionizing particle traverses the 30 nm chromatin fiber with generation of heavily damaged DNA regions with an average size of about 2 kbp. On an even larger scale, high LET radiation can produce several DNA double-strand breaks in closer proximity than expected from randomness. It is suggested that this increases the probability of misrejoining of DNA ends and generation of lethal chromosome aberrations.

Rydberg, B.; Chatterjee, A. (Principal Investigator)

2001-01-01

186

Mechanisms of radiation-induced gene responses  

SciTech Connect

In the process of identifying genes differentially expressed in cells exposed ultraviolet radiation, we have identified a transcript having a 26-bp region that is highly conserved in a variety of species including Bacillus circulans, yeast, pumpkin, Drosophila, mouse, and man. When the 5` region (flanking region or UTR) of a gene, the sequence is predominantly in +/+ orientation with respect to the coding DNA strand; while in the coding region and the 3` region (UTR), the sequence is most frequently in the +/-orientation with respect to the coding DNA strand. In two genes, the element is split into two parts; however, in most cases, it is found only once but with a minimum of 11 consecutive nucleotides precisely depicting the original sequence. The element is found in a large number of different genes with diverse functions (from human ras p21 to B. circulans chitonase). Gel shift assays demonstrated the presence of a protein in HeLa cell extracts that binds to the sense and antisense single-stranded consensus oligomers, as well as to the double- stranded oligonucleotide. When double-stranded oligomer was used, the size shift demonstrated as additional protein-oligomer complex larger than the one bound to either sense or antisense single-stranded consensus oligomers alone. It is speculated either that this element binds to protein(s) important in maintaining DNA is a single-stranded orientation for transcription or, alternatively that this element is important in the transcription-coupled DNA repair process.

Woloschak, G.E.; Paunesku, T.

1996-10-01

187

Approach to estimating the maximum depth for glacially induced hydraulic jacking in fractured crystalline rock at Forsmark, Sweden  

NASA Astrophysics Data System (ADS)

Hydraulic jacking is a significant dilation of a fracture that occurs when the pore pressure within it exceeds the sum of the fracture's normal stress and tensile strength. This phenomenon may occur during a glacial period because of changes in hydraulic and mechanical boundary conditions. Since hydraulic jacking may alter flow patterns and the transport capacity of the rock mass, its possible effects on the long-term performance of a nuclear waste repository should be considered. We develop an approach to assess glacially induced hydraulic jacking in fractured crystalline rock and establish bounding estimates of the maximum jacking depth for the Swedish Nuclear Fuel and Waste Management Company's (SKB) repository site at Forsmark. The pore pressure is estimated using mechanically uncoupled two-dimensional poroelastic continuum models with hydraulic and mechanical conditions based on SKB's reconstruction of the Weichselian glaciation at this site (120-0 ka B.P.). For warm-based conditions, the water pressure at the ice/bed interface is set at 98% of the mechanical load, whereas for glacial conditions with extensive proglacial permafrost, the corresponding water pressure is set at a (lower) annual average value. We demonstrate that the pore pressure within the uppermost kilometer of rock is mainly governed by the water pressure at the ice/bed interface and that the mechanical impact of the ice load on the pore pressure is sufficiently small to be ignored. Given the current and estimated future stress conditions at Forsmark, hydraulic jacking is mainly of concern for subhorizontal fractures, i.e., it is sufficient to consider situations when the pore pressure exceeds the vertical stress. We conclude that hydraulic jacking at Forsmark will be confined to the uppermost 200 m of the rock mass.

Lönnqvist, M.; Hökmark, H.

2013-09-01

188

Dynamics of plasma formation, relaxation, and topography modification induced by femtosecond laser pulses in crystalline and amorphous dielectrics  

SciTech Connect

We have studied plasma formation and relaxation dynamics along with the corresponding topography modifications in fused silica and sapphire induced by single femtosecond laser pulses (800 nm and 120 fs). These materials, representative of high bandgap amorphous and crystalline dielectrics, respectively, require nonlinear mechanisms to absorb the laser light. The study employed a femtosecond time-resolved microscopy technique that allows obtaining reflectivity and transmission images of the material surface at well-defined temporal delays after the arrival of the pump pulse which excites the dielectric material. The transient evolution of the free-electron plasma formed can be followed by combining the time-resolved optical data with a Drude model to estimate transient electron densities and skin depths. The temporal evolution of the optical properties is very similar in both materials within the first few hundred picoseconds, including the formation of a high reflectivity ring at about 7 ps. In contrast, at longer delays (100 ps-20 ns) the behavior of both materials differs significantly, revealing a longer lasting ablation process in sapphire. Moreover, transient images of sapphire show a concentric ring pattern surrounding the ablation crater, which is not observed in fused silica. We attribute this phenomenon to optical diffraction at a transient elevation of the ejected molten material at the crater border. On the other hand, the final topography of the ablation crater is radically different for each material. While in fused silica a relatively smooth crater with two distinct regimes is observed, sapphire shows much steeper crater walls, surrounded by a weak depression along with cracks in the material surface. These differences are explained in terms of the most relevant thermal and mechanical properties of the material. Despite these differences the maximum crater depth is comparable in both material at the highest fluences used (16 J/cm{sup 2}). The evolution of the crater depth as a function of fluence can be described taking into account the individual bandgap of each material.

Puerto, D.; Siegel, J.; Gawelda, W.; Galvan-Sosa, M.; Solis, J. [Laser Processing Group, Instituto de Optica-CSIC, Madrid (Spain); Ehrentraut, L. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, Berlin (Germany); Bonse, J. [Bundesanstalt fuer Materialforschung und-pruefung (BAM), Berlin (Germany)

2010-05-15

189

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

190

Electron-beam induced terahertz radiation from graded metallic grating.  

PubMed

We have numerically analyzed, based on a simplified particle-in-cell finite-difference time-domain (PIC-FDTD) method, an electron-beam (e-beam) induced terahertz (THz) radiation from metallic grating structures with graded depths (graded grating). Upon exciting with e-beam, directional THz radiations with wide-band spectrum containing several sharp peaks are obtained only from the one of the edge of the grating, which cannot be expected from the conventional theory of Smith-Purcell radiation. It was clarified that each modes originate from different locations on the graded grating reflecting different dispersion characteristics of spoof surface plasmon polariton (spoof SPP) at each locations, and they can propagate toward only the shallower groove as a surface wave due to the cutoff at each locations, and all of these modes eventually emitted from the one of the edge of the graded grating. These directional radiations can be directed toward either backward or forward by making the groove depth deeper or shallower. The lowest and the highest frequency of the radiation can be chosen by appropriately designing the deepest and the shallowest groove depths, respectively. These unique radiations cannot be obtained from the uniformly grooved grating. Our findings may open the way for a development of novel THz radiation source based on the spoof SPP on the wide variety of metallic grating structures or metasurfaces. PMID:25090564

Okajima, Akiko; Matsui, Tatsunosuke

2014-07-14

191

Radiation-Induced Notch Signaling in Breast Cancer Stem Cells  

SciTech Connect

Purpose: To explore patterns of Notch receptor and ligand expression in response to radiation that could be crucial in defining optimal dosing schemes for ?-secretase inhibitors if combined with radiation. Methods and Materials: Using MCF-7 and T47D breast cancer cell lines, we used real-time reverse transcription–polymerase chain reaction to study the Notch pathway in response to radiation. Results: We show that Notch receptor and ligand expression during the first 48 hours after irradiation followed a complex radiation dose–dependent pattern and was most pronounced in mammospheres, enriched for breast cancer stem cells. Additionally, radiation activated the Notch pathway. Treatment with a ?-secretase inhibitor prevented radiation-induced Notch family gene expression and led to a significant reduction in the size of the breast cancer stem cell pool. Conclusions: Our results indicate that, if combined with radiation, ?-secretase inhibitors may prevent up-regulation of Notch receptor and ligand family members and thus reduce the number of surviving breast cancer stem cells.

Lagadec, Chann [Department of Radiation Oncology, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California (United States); Vlashi, Erina [Department of Radiation Oncology, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California (United States); Jonsson Comprehensive Cancer Center at UCLA, Los Angeles, California (United States); Alhiyari, Yazeed; Phillips, Tiffany M.; Bochkur Dratver, Milana [Department of Radiation Oncology, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California (United States); Pajonk, Frank, E-mail: fpajonk@mednet.ucla.edu [Department of Radiation Oncology, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California (United States); Jonsson Comprehensive Cancer Center at UCLA, Los Angeles, California (United States)

2013-11-01

192

Pivotal role of augmented ?B-crystallin in tumor development induced by deficient TSC1/2 complex.  

PubMed

Tuberous sclerosis complex 1 (TSC1) and TSC2 are suppressors of mechanistic target of rapamycin (mTOR). mTOR is the major component of two protein complexes: mTOR complex 1 (mTORC1) and mTORC2. Inactive mutation of either TSC1 or TSC2 unleashes mTOR signaling and consequently causes TSC, a benign tumor syndrome affecting multiple organs. We report here that expression of ?B-crystallin was upregulated in Tsc1-/- or Tsc2-/- mouse embryonic fibroblasts, Eker rat uterine leiomyoma-derived Tsc2-deficient ELT3 cells, mutant Tsc2-associated mouse kidney tumors, and human lung lymphangioleiomyomatosis nodules. ?B-crystallin was transcriptionally activated by mTOR complex 2 (mTORC2): nuclear factor-kappa B (NF?B) signaling cascade. The augmented ?B-crystallin was critical for the migration, invasion and apoptotic resistance of Tsc2-defective cells. Disruption of ?B-crystallin suppressed Tsc2-null cell proliferation and tumorigenesis. Therefore, enhanced ?B-crystallin has an essential role in TSC1/2 complex deficiency-mediated tumorigenesis, and inhibition of ?B-crystallin may complement the current therapy for TSC. PMID:24077282

Wang, F; Chen, X; Li, C; Sun, Q; Chen, Y; Wang, Y; Peng, H; Liu, Z; Chen, R; Liu, K; Yan, H; Ye, B H; Kwiatkowski, D J; Zhang, H

2014-08-21

193

Modeling radiation-induced mixing at interfaces between low solubility metals  

E-print Network

This thesis studies radiation-induced mixing at interfaces between low solubility metals using molecular dynamics (MD) computer simulations. It provides original contributions on the fundamental mechanisms of radiation-induced ...

Zhang, Liang, Ph. D. Massachusetts Institute of Technology

2014-01-01

194

Chromosome aberrations induced by high-LET radiations  

NASA Technical Reports Server (NTRS)

Measurements of chromosome aberrations in peripheral blood lymphocytes are currently the most sensitive and reliable indicator of radiation exposure that can be used for biological dosimetry. This technique has been implemented recently to study radiation exposures incurred by astronauts during space flight, where a significant proportion of the dose is delivered by high-LET particle exposure. Traditional methods for the assessing of cytogenetic damage in mitotic cells collected at one time point after exposure may not be suitable for measuring high-LET radiation effects due to the drastic cell cycle perturbations and interphase cell death induced by this type of exposure. In this manuscript we review the recent advances in methodology used to study high-LET induced cytogenetic effects and evaluate the use of chemically-induced Premature Chromosome Condensation (PCC) as an alternative to metaphase analysis. Published data on the cytogenetic effects of in vitro exposures of high-LET radiation is reviewed, along with biodosimetry results from astronauts after short or long space missions.

Kawata, Tetsuya; Ito, Hisao; George, Kerry; Wu, Honglu; Cucinotta, Francis A.

2004-01-01

195

Radiation-induced optic neuropathy: A magnetic resonance imaging study  

SciTech Connect

Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence of both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.

Guy, J.; Mancuso, A.; Beck, R.; Moster, M.L.; Sedwick, L.A.; Quisling, R.G.; Rhoton, A.L. Jr.; Protzko, E.E.; Schiffman, J. (Univ. of Florida, Gainesville (USA))

1991-03-01

196

Nature of Radiation-Induced Defects in Quartz  

E-print Network

Although quartz ($\\rm \\alpha$-form) is a mineral used in numerous applications wherein radiation exposure is an issue, the nature of the atomistic defects formed during radiation-induced damage have not been fully clarified. Especially, the extent of oxygen vacancy formation is still debated, which is an issue of primary importance as optical techniques based on charged oxygen vacancies have been utilized to assess the level of radiation damage in quartz. In this paper, molecular dynamics (MD) simulations are applied to study the effects of ballistic impacts on the atomic network of quartz. We show that the defects that are formed mainly consist of over-coordinated Si and O, as well as Si--O connectivity defects, e.g., small Si--O rings and edge-sharing Si tetrahedra. Oxygen vacancies, on the contrary, are found in relatively low abundance, suggesting that characterizations based on $E^{\\prime}$ centers do not adequately capture radiation-induced structural damage in quartz. Finally, we evaluate the dependence on the incident energy, of the amount of each type of the point defects formed, and quantify unambiguously the threshold displacement energies for both O and Si atoms. These results provide a comprehensive basis to assess the nature and extent of radiation damage in quartz.

Bu Wang; Yingtian Yu; Isabella Pignatelli; Gaurav N. Sant; Mathieu Bauchy

2015-04-10

197

Radiation induced corrosion of copper for spent nuclear fuel storage  

NASA Astrophysics Data System (ADS)

The long term safety of repositories for radioactive waste is one of the main concerns for countries utilizing nuclear power. The integrity of engineered and natural barriers in such repositories must be carefully evaluated in order to minimize the release of radionuclides to the biosphere. One of the most developed concepts of long term storage of spent nuclear fuel is the Swedish KBS-3 method. According to this method, the spent fuel will be sealed inside copper canisters surrounded by bentonite clay and placed 500 m down in stable bedrock. Despite the importance of the process of radiation induced corrosion of copper, relatively few studies have been reported. In this work the effect of the total gamma dose on radiation induced corrosion of copper in anoxic pure water has been studied experimentally. Copper samples submerged in water were exposed to a series of total doses using three different dose rates. Unirradiated samples were used as reference samples throughout. The copper surfaces were examined qualitatively using IRAS and XPS and quantitatively using cathodic reduction. The concentration of copper in solution after irradiation was measured using ICP-AES. The influence of aqueous radiation chemistry on the corrosion process was evaluated based on numerical simulations. The experiments show that the dissolution as well as the oxide layer thickness increase upon radiation. Interestingly, the evaluation using numerical simulations indicates that aqueous radiation chemistry is not the only process driving the corrosion of copper in these systems.

Björkbacka, Åsa; Hosseinpour, Saman; Johnson, Magnus; Leygraf, Christofer; Jonsson, Mats

2013-11-01

198

Evidence for Radiation-Induced Disseminated Intravascular Coagulation as a Major Cause of Radiation-Induced Death in Ferrets  

PubMed Central

Purpose/Objectives(s) The studies reported here were performed as part of a program in space radiation biology in which proton radiation like that present in solar particle events (SPEs), as well as conventional gamma radiation, were being evaluated in terms of the ability to affect hemostasis. Methods and Materials Ferrets were exposed to 0 – 2 Gray (Gy) of whole body proton or gamma radiation and monitored for 30 days. Blood was analyzed for blood cell counts, platelet clumping, thromboelastometry, and fibrin clot formation. Results The lethal dose of radiation to 50% of the population, known as the LD50, of ferrets was established at ~ 1.5 Gy, with 100% mortality at 2 Gy. Hypocoagulability was present as early as day 7 post-irradiation, with animals unable to generate a stable clot and exhibiting signs of platelet aggregation, thrombocytopenia, and fibrin clots in blood vessels of organs. Platelet counts were at normal levels during the early times post-irradiation when coagulopathies were present and progressively becoming more severe; platelet counts were greatly reduced at the time of the white blood cell nadir of 13 days. Conclusions The data presented here provide evidence that death at the LD50 in ferrets is most likely due to disseminated intravascular coagulation (DIC). These data question the current hypothesis that death at relatively low doses of radiation is solely due to the cell killing effects of hematopoietic cells. The recognition that radiation-induced DIC is the most likely mechanism of death in ferrets raises the question of whether DIC is a contributing mechanism to radiation induced death at relatively low doses in large mammals. PMID:24495588

Krigsfeld, Gabriel S.; Savage, Alexandria R.; Billings, Paul C.; Lin, Liyong; Kennedy, Ann R.

2014-01-01

199

The radiation-induced changes in rectal mucosa: Hyperfractionated vs. hypofractionated preoperative radiation for rectal cancer  

SciTech Connect

Purpose: The purpose of the study was the qualitative and quantitative evaluation of acute radiation-induced rectal changes in patients who underwent preoperative radiotherapy according to two different irradiation protocols. Patients and Methods: Sixty-eight patients with rectal adenocarcinoma underwent preoperative radiotherapy; 44 and 24 patients underwent hyperfractionated and hypofractionated protocol, respectively. Fifteen patients treated with surgery alone served as a control group. Five basic histopathologic features (meganucleosis, inflammatory infiltrations, eosinophils, mucus secretion, and erosions) and two additional features (mitotic figures and architectural glandular abnormalities) of radiation-induced changes were qualified and quantified. Results: Acute radiation-induced reactions were found in 66 patients. The most common were eosinophilic and plasma-cell inflammatory infiltrations (65 patients), erosions, and decreased mucus secretion (54 patients). Meganucleosis and mitotic figures were more common in patients who underwent hyperfractionated radiotherapy. The least common were the glandular architectural distortions, especially in patients treated with hypofractionated radiotherapy. Statistically significant differences in morphologic parameters studied between groups treated with different irradiation protocols were found. Conclusion: The system of assessment is a valuable tool in the evaluation of radiation-induced changes in the rectal mucosa. A greater intensity of regenerative changes was found in patients treated with hyperfractionated radiotherapy.

Starzewski, Jacek J. [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland); Pajak, Jacek T. [Department of Pathology, Medical University of Silesia, Katowice (Poland); Pawelczyk, Iwona [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland); Lange, Dariusz [Department of Tumor Pathology, Comprehensive Cancer Center Division, Gliwice (Poland); Golka, Dariusz [Department of Pathology, Medical University of Silesia, Katowice (Poland)]. E-mail: dargolka@wp.pl; Brzeziska, Monika [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland); Lorenc, Zbigniew [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland)

2006-03-01

200

Radiation-induced cardiomyopathy as a function of radiation beam gating to the cardiac cycle  

NASA Astrophysics Data System (ADS)

Portions of the heart are often unavoidably included in the primary treatment volume during thoracic radiotherapy, and radiation-induced heart disease has been observed as a treatment-related complication. Such complications have been observed in humans following radiation therapy for Hodgkin's disease and treatment of the left breast for carcinoma. Recent attempts have been made to prevent re-stenosis following angioplasty procedures using external beam irradiation. These attempts were not successful, however, due to the large volume of heart included in the treatment field and subsequent cardiac morbidity. We suggest a mechanism for sparing the heart from radiation damage by synchronizing the radiation beam with the cardiac cycle and delivering radiation only when the heart is in a relatively hypoxic state. We present data from a rat model testing this hypothesis and show that radiation damage to the heart can be altered by synchronizing the radiation beam with the cardiac cycle. This technique may be useful in reducing radiation damage to the heart secondary to treatment for diseases such as Hodgkin's disease and breast cancer.

Gladstone, David J.; Flanagan, Michael F.; Southworth, Jean B.; Hadley, Vaughn; Thibualt, Melissa Wei; Hug, Eugen B.; Hoopes, P. Jack

2004-04-01

201

Comparison of radiation-induced transmission degradation of borosilicate crown optical glass from four different manufacturers  

E-print Network

Comparison of radiation-induced transmission degradation of borosilicate crown optical glass from manufacturers is different. We studied the gamma-radiation induced absorption of several crown glasses with nd compare the gamma-radiation induced absorption of several crown glasses with nd 1.516 (d = 587.56 nm

Glebov, Leon

202

Titanium carbide nanocube core induced interfacial growth of crystalline polypyrrole/polyvinyl alcohol lamellar shell for wide-temperature range supercapacitors  

NASA Astrophysics Data System (ADS)

This is the first investigation on electrically conducting polymers-based supercapacitor electrodes over a wide temperature range, from -18 °C to 60 °C. A high-performance supercapacitor electrode material consisting of TiC nanocube core and conformal crystalline polypyrrole (PPy)/poly-vinyl-alcohol (PVA) lamellar shell has been synthesized by heterogeneous nucleation-induced interfacial crystallization. PPy is induced to crystallize on the negatively charged TiC nanocube surfaces via strong interfacial interactions. In this organic-inorganic hybrid nanocomposite, the long chain PVA enables enhanced cycle life due to improved mechanical properties, and the TiC nanocube not only contributes to electron conduction, but also dictates the PPy morphology/crystallinity for maximizing the charging-discharging performance. The crystalline PPy/PAV layer on the TiC nanocube offers unprecedented high capacity (>350 F g-1-PPy at 300 mV s-1 with ?V = 1.6 V) and cycling stability in a temperature range from -18 °C to 60 °C. The presented hybrid-filler and interfacial crystallization strategies can be applied to the exploration of new-generation high-power conducting polymer-based supercapacitor materials.

Weng, Yu-Ting; Pan, Hsiao-An; Wu, Nae-Lih; Chen, Geroge Zheng

2015-01-01

203

Quantification of anti-aggregation activity of UV-irradiated ?-crystallin.  

PubMed

Ultraviolet radiation is a risk factor for cataractogenesis. It is believed that enhanced rates of lens opacification and cataract formation are the results of gradual loss of chaperone-like efficiency of ?-crystallin upon exposure to UV light. To characterize chaperone-like activity of ?-crystallin damaged by UV irradiation, a test system based on dithiothreitol-induced aggregation of holo-?-lactalbumin from bovine milk was used. The adsorption capacity of ?-crystallin (AC0) with respect to the target protein (?-lactalbumin) was used as a measure of anti-aggregation activity of ?-crystallin. The data on SDS-PAGE testify that UV irradiation of ?-crystallin results in covalent cross-linking of subunits in ?-crystallin oligomers. The dependence of AC0 value on the irradiation dose was compared with the UV-induced diminution of the portion of native ?-crystallin estimated from the data on differential scanning calorimetry. On the basis of such comparison a conclusion has been made that the loss in chaperone-like activity is mainly due to UV-induced denaturation of ?-crystallin subunits. Cross-linking of remaining native subunits leads to an additional decrease in anti-aggregation activity. PMID:25445690

Borzova, Vera A; Markossian, Kira A; Muranov, Konstantin O; Polyansky, Nikolay B; Kleymenov, Sergey Yu; Kurganov, Boris I

2015-02-01

204

Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic Strings  

E-print Network

We report on a current investigation of the anisotropy pattern induced by cosmic strings on the cosmic microwave background radiation (MBR). We have numerically evolved a network of cosmic strings from a redshift of $Z = 100$ to the present and calculated the anisotropies which they induce. Based on a limited number of realizations, we have compared the results of our simulations with the observations of the COBE-DMR experiment. We have obtained a preliminary estimate of the string mass-per-unit-length $\\mu$ in the cosmic string scenario.

B. Allen; R. R. Caldwell; E. P. S. Shellard; A. Stebbins; S. Veeraraghavan

1994-07-14

205

Residual stress induced crystalline to amorphous phase transformation in Nb{sub 2}O{sub 5} quantum dots  

SciTech Connect

Nb{sub 2}O{sub 5} quantum dots (QDs) were grown using a simple technique of vacuum thermal evaporation. QDs were found to be crystalline in nature by selected area electron diffraction (SAED) in TEM. Samples with thickness up to 20?nm did not show any significant residual strain. Residual stress effect on band gap of crystalline Nb{sub 2}O{sub 5} was studied for films thicker than 20?nm. Residual strain was determined using SAED of the films with reference to powder X-ray diffraction (XRD). Films thicker than 45?nm become amorphous as analyzed by both SAED and XRD. The optical absorption of films in the range 25–60?nm indicates significantly varying optical band gap of films. The varying band gap with film thickness scales linearly very well with the variation of residual stress with film thickness. The residual stress dependence of band gap of crystalline films yields stress free band gap as 3.37 eV with pressure coefficient of band gap (?E{sub g}/?P){sub T}?=??29.3?meV/GPa. From this study, the crystalline to amorphous transformation in tetragonal form of M-Nb{sub 2}O{sub 5} has been determined to be at about 14?GPa. Both pressure coefficient of band gap and crystalline to amorphous transition for tetragonal M-Nb{sub 2}O{sub 5} have been determined for the first time in the literature.

Dhawan, Sahil; Vedeshwar, Agnikumar G. [Thin Film Laboratory, Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Dhawan, Tanuj, E-mail: tanuj-physics@yahoo.com [Department of Physics and Electronics, Hans Raj College, University of Delhi, Delhi 110007 (India)

2014-07-28

206

Caffeine Markedly Enhanced Radiation-Induced Bystander Effects  

NASA Astrophysics Data System (ADS)

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

Jiang, Erkang; Wu, Lijun

2009-04-01

207

[Radiation-induced and therapy-related AML/MDS].  

PubMed

Radiation induced acute myeloid leukemia (AML) was recognized a century ago, soon after mankind found radiation. Atomic bomb survivors developed de novo AML with relatively short latency with very high frequency. By contrast, excess occurrence of myelodysplastic syndrome (MDS) as well as solid tumors was found decades late. This difference may be due to etiology that many de novo AML patients harbor chimeric leukemogenic genes caused by chromosomal translocations, while MDS patients rarely carry chimeras. In addition, epigenetic change would play important roles. Therapy related leukemia is mainly caused by topoisomerase II inhibitors that cause de novo AML with an 11q23 translocation or by alkyrating agents that induce MDS/AML with an AML1 point mutation and monosomy 7. PMID:19860183

Inaba, Toshiya

2009-10-01

208

Probabilistic methodology for estimating radiation-induced cancer risk  

SciTech Connect

The RICRAC computer code was developed at Oak Ridge National Laboratory to provide a versatile and convenient methodology for radiation risk assessment. The code allows as input essentially any dose pattern commonly encountered in risk assessments for either acute or chronic exposures, and it includes consideration of the age structure of the exposed population. Results produced by the analysis include the probability of one or more radiation-induced cancer deaths in a specified population, expected numbers of deaths, and expected years of life lost as a result of premature fatalities. These calculatons include consideration of competing risks of death from all other causes. The program also generates a probability frequency distribution of the expected number of cancers in any specified cohort resulting from a given radiation dose. The methods may be applied to any specified population and dose scenario.

Dunning, D.E. Jr.; Leggett, R.W.; Williams, L.R.

1981-01-01

209

Radiation-induced bystander effect: early process and rapid assessment.  

PubMed

Radiation-induced bystander effect (RIBE) is a biological process that has received attention over the past two decades. RIBE refers to a plethora of biological effects in non-irradiated cells, including induction of genetic damages, gene expression, cell transformation, proliferation and cell death, which are initiated by receiving bystander signals released from irradiated cells. RIBE brings potential hazards to normal tissues in radiotherapy, and imparts a higher risk from low-dose radiation than we previously thought. Detection with proteins related to DNA damage and repair, cell cycle control, proliferation, etc. have enabled rapid assessment of RIBE in a number of research systems such as cultured cells, three-dimensional tissue models and animal models. Accumulated experimental data have suggested that RIBE may be initiated rapidly within a time frame as short as several minutes after radiation. These have led to the requirement of techniques capable of rapidly assessing RIBE itself as well as assessing the early processes involved. PMID:24139967

Wang, Hongzhi; Yu, K N; Hou, Jue; Liu, Qian; Han, Wei

2015-01-01

210

Radiation-induced transient absorption in single mode optical fibers  

SciTech Connect

This paper reviews the measurements conducted by the Los Alamos National Laboratory in support of these NATO efforts wherein radiation-induced transient absorption was measured over time ranges from a few ns to several ..mu..s for two single mode fibers. Experimental conditions were varied to provide data for future development of standarized test conditions for single mode fibers. 8 refs., 11 figs.

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

1988-01-01

211

Radiation induced decomposition of hydrocarbons in water resources  

NASA Astrophysics Data System (ADS)

Radiation induced decomposition of various organic compounds, such as phenols, chlorinated hydrocarbons, dyestuffs etc. in water represents a new and very efficient possibility for elimination of the steadily increasing pollution. Experimental results considering the removal of phenol, phenolic compounds, mixture of aliphatic and aromatic hydrocarbons, as well as chlorinated compounds etc. in waste water under irradiation were reported. Basic considerations of probable reaction mechanisms were also presented.

Getoff, N.; Lutz, W.

212

Heat Induced Damage Detection by Terahertz (THz) Radiation  

Microsoft Academic Search

Terahertz (THz) and sub-terahertz imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques\\u000a for damage detection and characterization of materials. THz radiation is being used for inspecting ceramic foam tiles used\\u000a in TPS (Thermal Protection System), thick polymer composites and polymer tiles that are not good conductors of ultrasonic\\u000a waves. Capability of THz electromagnetic waves in detecting heat induced

Ehsan Kabiri Rahani; Tribikram Kundu; Ziran Wu; Hao Xin

2011-01-01

213

Opportunities for nutritional amelioration of radiation-induced cellular damage  

NASA Technical Reports Server (NTRS)

The closed environment and limited evasive capabilities inherent in space flight cause astronauts to be exposed to many potential harmful agents (chemical contaminants in the environment and cosmic radiation exposure). Current power systems used to achieve space flight are prohibitively expensive for supporting the weight requirements to fully shield astronauts from cosmic radiation. Therefore, radiation poses a major, currently unresolvable risk for astronauts, especially for long-duration space flights. The major detrimental radiation effects that are of primary concern for long-duration space flights are damage to the lens of the eye, damage to the immune system, damage to the central nervous system, and cancer. In addition to the direct damage to biological molecules in cells, radiation exposure induces oxidative damage. Many natural antioxidants, whether consumed before or after radiation exposure, are able to confer some level of radioprotection. In addition to achieving beneficial effects from long-known antioxidants such as vitamins E and C and folic acid, some protection is conferred by several recently discovered antioxidant molecules, such as flavonoids, epigallocatechin, and other polyphenols. Somewhat counterintuitive is the protection provided by diets containing elevated levels of omega-3 polyunsaturated fatty acids, considering they are thought to be prone to peroxidation. Even with the information we have at our disposal, it will be difficult to predict the types of dietary modifications that can best reduce the risk of radiation exposure to astronauts, those living on Earth, or those enduring diagnostic or therapeutic radiation exposure. Much more work must be done in humans, whether on Earth or, preferably, in space, before we are able to make concrete recommendations.

Turner, Nancy D.; Braby, Leslie A.; Ford, John; Lupton, Joanne R.

2002-01-01

214

Radiation-Induced Alterations in Mitochondria of the Rat Heart  

PubMed Central

Radiation therapy for the treatment of thoracic cancers may be associated with radiation-induced heart disease (RIHD), especially in long-term cancer survivors. Mechanisms by which radiation causes heart disease are largely unknown. To identify potential long-term contributions of mitochondria in the development of radiation-induced heart disease, we examined the time course of effects of irradiation on cardiac mitochondria. In this study, Sprague-Dawley male rats received image-guided local X irradiation of the heart with a single dose ranging from 3–21 Gy. Two weeks after irradiation, left ventricular mitochondria were isolated to assess the dose-dependency of the mitochondrial permeability transition pore (mPTP) opening in a mitochondrial swelling assay. At time points from 6 h to 9 months after a cardiac dose of 21 Gy, the following analyses were performed: left ventricular Bax and Bcl-2 protein levels; apoptosis; mitochondrial inner membrane potential and mPTP opening; mitochondrial mass and expression of mitophagy mediators Parkin and PTEN induced putative kinase-1 (PINK-1); mitochondrial respiration and protein levels of succinate dehydrogenase A (SDHA); and the 70 kDa subunit of complex II. Local heart irradiation caused a prolonged increase in Bax/Bcl-2 ratio and induced apoptosis between 6 h and 2 weeks. The mitochondrial membrane potential was reduced until 2 weeks, and the calcium-induced mPTP opening was increased from 6 h up to 9 months. An increased mitochondrial mass together with unaltered levels of Parkin suggested that mitophagy did not occur. Lastly, we detected a significant decrease in succinate-driven state 2 respiration in isolated mitochondria from 2 weeks up to 9 months after irradiation, coinciding with reduced mitochondrial levels of succinate dehydrogenase A. Our results suggest that local heart irradiation induces long-term changes in cardiac mitochondrial membrane functions, levels of SDH and state 2 respiration. At any time after exposure to radiation, cardiac mitochondria are more prone to mPTP opening. Future studies will determine whether this makes the heart more susceptible to secondary stressors such as calcium overload or ischemia/reperfusion. PMID:24568130

Sridharan, Vijayalakshmi; Aykin-Burns, Nukhet; Tripathi, Preeti; Krager, Kimberly J.; Sharma, Sunil K.; Moros, Eduardo G.; Corry, Peter M.; Nowak, Grazyna; Hauer-Jensen, Martin; Boerma, Marjan

2014-01-01

215

Nature of Radiation-Induced Defects in Quartz  

E-print Network

Although quartz ($\\rm \\alpha$-form) is a mineral used in numerous applications wherein radiation exposure is an issue, the nature of the atomistic defects formed during radiation-induced damage have not been fully clarified. Especially, the extent of oxygen vacancy formation is still debated, which is an issue of primary importance as optical techniques based on charged oxygen vacancies have been utilized to assess the level of radiation damage in quartz. In this paper, molecular dynamics (MD) simulations are applied to study the effects of ballistic impacts on the atomic network of quartz. We show that the defects that are formed mainly consist of over-coordinated Si and O, as well as Si--O connectivity defects, e.g., small Si--O rings and edge-sharing Si tetrahedra. Oxygen vacancies, on the contrary, are found in relatively low abundance, suggesting that characterizations based on $E^{\\prime}$ centers do not adequately capture radiation-induced structural damage in quartz. Finally, we evaluate the dependenc...

Wang, Bu; Pignatelli, Isabella; Sant, Gaurav N; Bauchy, Mathieu

2015-01-01

216

Delayed Diagnosis of Probable Radiation Induced Spinal Cord Vascular Disorders  

PubMed Central

Occasionally, unexpected neurological deficits occur after lumbar spinal surgery. We report a case of monoparesis after lumbar decompressive surgery. A 63-year-old man, who had undergone decompression of L4-5 for spinal stenosis 4 days previously in the other hospital, visted the emergency department with progressive weakness in the left leg and hypoesthesia below sensory level T7 on the right side. He had been cured of lung cancer with chemotherapy and radiation therapy 10 years previously, but detailed information of radiotherapy was not available. Whole spine magnetic resonance (MR) imaging showed fatty marrow change from T1 to T8, most likely due to previous irradiation. The T2-weighted MR image showed a high-signal T4-5 spinal cord lesion surrounded by a low signal rim, and the T1-weighted MR image showed focal high signal intensity with focal enhancement. The radiological diagnosis was vascular disorders with suspicious bleeding. Surgical removal was refused by the patient. With rehabilitation, the patient could walk independently without assistance 2 months later. Considering radiation induced change at thoracic vertebrae, vascular disorders may be induced by irradiation. If the spinal cord was previously irradiated, radiation induced vascular disorders needs to be considered. PMID:25810864

Won, Young Il; Chung, Chun Kee; Yun, Tae Jin

2015-01-01

217

UV radiation induces CXCL5 expression in human skin.  

PubMed

CXCL5 has recently been identified as a mediator of UVB-induced pain in rodents. To compare and to extend previous knowledge of cutaneous CXCL5 regulation, we performed a comprehensive study on the effects of UV radiation on CXCL5 regulation in human skin. Our results show a dose-dependent increase in CXCL5 protein in human skin after UV radiation. CXCL5 can be released by different cell types in the skin. We presumed that, in addition to immune cells, non-immune skin cells also contribute to UV-induced increase in CXCL5 protein. Analysis of monocultured dermal fibroblasts and keratinocytes revealed that only fibroblasts but not keratinocytes displayed up regulated CXCL5 levels after UV stimulation. Whereas UV treatment of human skin equivalents, induced epidermal CXCL5 mRNA and protein expression. Up regulation of epidermal CXCL5 was independent of keratinocyte differentiation and keratinocyte-keratinocyte interactions in epidermal layers. Our findings provide first evidence on the release of CXCL5 in UV-radiated human skin and the essential role of fibroblast-keratinocyte interaction in the regulation of epidermal CXCL5. PMID:25690483

Reichert, Olga; Kolbe, Ludger; Terstegen, Lara; Staeb, Franz; Wenck, Horst; Schmelz, Martin; Genth, Harald; Kaever, Volkhard; Roggenkamp, Dennis; Neufang, Gitta

2015-04-01

218

Interface-induced crystalline ordering and favorable morphology for efficient annealing-free poly(3-hexylthiophene): fullerene derivative solar cells.  

PubMed

A simple approach to fabricate high-efficiency annealing-free poly(3-hexylthiophene): [6,6]-phenyl C(61)-butyric acid methyl ester (P3HT:PCBM) solar cells is reported by using p-type CuI to substitute PEDOT:PSS as anode buffer layer. It is found that the P3HT:PCBM blend films deposited on CuI surface show different orientation of crystalline P3HT domains and phase separation from those deposited on PEDOT:PSS surface. A nanoscale phase separation of P3HT and PCBM with domain sizes about 10-30 nm is formed for the P3HT:PCBM blend films deposited on CuI surface. Absorption and grazing incidence X-ray diffraction (GIXRD) experiments indicate that the CuI layer not only induces the self-organization of P3HT chains into well-ordered structure but also results in the vertical orientation of ?-? stacking planes of P3HT with respect to the substrate which is favorable for the hole collection in polymer solar cells. Hole-transport investigation discloses that hole mobility of the as-spincast P3HT:PCBM blend film on CuI surface is increased with 3 orders of magnitude compared to the P3HT:PCBM film deposited on PEDOT:PSS. A power conversion efficiency of 3.1% for the as-spincast P3HT:PCBM solar cell with CuI buffer layer is about 4-fold enhancement compared to 0.83% of the control device with PEDOT:PSS, and is comparable to the reported P3HT:PCBM solar cells subjected to post thermal treatments. This work implies that interfacial engineering is a promising approach for manipulating morphology of active layer and can potentially simplify the process and shorten the fabrication time of polymer solar cells in low-cost roll-to-roll manufacturing. PMID:23027773

Shao, Shuyan; Liu, Jian; Zhang, Jidong; Zhang, Baohua; Xie, Zhiyuan; Geng, Yanhou; Wang, Lixiang

2012-10-24

219

Liquid-crystalline self-organization of isocyanide-containing dendrimers induced by coordination to gold(I) fragments.  

PubMed

Dendritic polyisocyanides can be considered as promising polytopic ligands to generate a great diversity of metallodendrimers due to the ability of the isocyanide moiety to bind to various transition metals. Here, new isocyanide-containing dendrimers and their corresponding polynuclear gold complexes have been prepared, [G(i)(NC)(Z)] and [G(i)(NCAuR)(Z)], respectively, where G(i) is a poly(phenyl ether) dendrimer, i is the generation number (i = 0, 1, or 2), Z is the number of peripheral groups (Z = 3 x 2(i)), and AuR are the surface groups ([R = Cl, C[triple bond]C-C(6)H(4)-OC(12)H(25), C[triple bond]CC(6)H(2)(OC(12)H(25))(3)]. The compounds are derived from a highly flexible phenyl ether-based dendritic core, G(i), having the general formula G(0) = C(6)H(3)(OC(11)H(22)OC(6)H(4)-)(3), G(1) = C(6)H(3)[OC(11)H(22)OC(6)H(3)(OC(11)H(22)OC(6)H(4)-)(2)](3), G(2) = C(6)H(3)[OC(11)H(22)OC(6)H(3){OC(11)H(22)OC(6)H(3)(OC(11)H(22)OC(6)H(4)-)(2)}(2)](3)), growing from the trivalent phloroglucinol and with undecylene aliphatic spacers between each branching benzene ring and end-functionalized by isocyanide groups. As in their monomeric model counterparts, stable liquid-crystalline phases are induced upon complexation of the AuR gold moieties at the branch termini. The nature of the anionic ligand R promotes the appearance of smectic or columnar mesophases, the formation of which are governed by steric and dipolar interactions. Based on X-ray diffraction experiments, models describing the supramolecular organization of these metallodendrimers into smectic and columnar mesophases are proposed: columnar phases result from the one-dimensional stacking of molecular disks made of self-assembled supermolecules in oblate cylindrical conformation, while the smectic phases form by the lateral two-dimensional registry of the supermolecules in antiparallel head-to-head prolate conformation. PMID:20055502

Cordovilla, Carlos; Coco, Silverio; Espinet, Pablo; Donnio, Bertrand

2010-02-01

220

Compression-induced texture change in NiMnGa-polymer composites observed by synchrotron radiation  

NASA Astrophysics Data System (ADS)

Composites consisting of magnetic shape memory (MSM) particles embedded in a polyester matrix were prepared. Single-crystalline MSM particles were obtained by mortar grinding of melt-extracted and subsequently annealed Ni50.9Mn27.1Ga22.0 (at. %) fibers. The crystal structure of the martensite is tetragonal (5M) with c induced twin boundary motion in the MSM particles, as the compressed composite is easy to magnetize in the direction of compression and more difficult to magnetize in the perpendicular directions. The texture of all the embedded MSM particles is investigated before and after compression by means of synchrotron radiation. In the initial state, the MSM particles in the composite have a random texture, i.e., there is no preferred orientation of the c axis. After a 30% compression (height reduction), the MSM particles have a (004)-fiber texture in the direction of compression. This is unambiguous evidence for stress induced twin boundary motion within the MSM particles.

Scheerbaum, Nils; Hinz, Dietrich; Gutfleisch, Oliver; Skrotzki, Werner; Schultz, Ludwig

2007-05-01

221

Countermeasures for Space Radiation Induced Malignancies and Acute Biological Effects  

NASA Astrophysics Data System (ADS)

The hypothesis being evaluated in this research program is that control of radiation induced oxidative stress will reduce the risk of radiation induced adverse biological effects occurring as a result of exposure to the types of radiation encountered during space travel. As part of this grant work, we have evaluated the protective effects of several antioxidants and dietary supplements and observed that a mixture of antioxidants (AOX), containing L-selenomethionine, N-acetyl cysteine (NAC), ascorbic acid, vitamin E succinate, and alpha-lipoic acid, is highly effective at reducing space radiation induced oxidative stress in both in vivo and in vitro systems, space radiation induced cytotoxicity and malignant transformation in vitro [1-7]. In studies designed to determine whether the AOX formulation could affect radiation induced mortality [8], it was observed that the AOX dietary supplement increased the 30-day survival of ICR male mice following exposure to a potentially lethal dose (8 Gy) of X-rays when given prior to or after animal irradiation. Pretreatment of animals with antioxidants resulted in significantly higher total white blood cell and neutrophil counts in peripheral blood at 4 and 24 hours following exposure to doses of 1 Gy and 8 Gy. Antioxidant treatment also resulted in increased bone marrow cell counts following irradiation, and prevented peripheral lymphopenia following 1 Gy irradiation. Supplementation with antioxidants in irradiated animals resulted in several gene expression changes: the antioxidant treatment was associated with increased Bcl-2, and decreased Bax, caspase-9 and TGF-?1 mRNA expression in the bone marrow following irradiation. These results suggest that modulation of apoptosis may be mechanistically involved in hematopoietic system radioprotection by antioxidants. Maintenance of the antioxidant diet was associated with improved recovery of the bone marrow following sub-lethal or potentially lethal irradiation. Taken together, oral supplementation with antioxidants appears to be an effective approach for the radioprotection of hematopoietic cells against the cell killing effects of radiation, and for improving survival in irradiated animals. Preliminary data suggest similar antioxidant protective effects for animals exposed to potentially lethal doses of proton radiation. Studies were also performed to determine whether dietary antioxidants could affect the incidence rates of malignancies in CBA mice exposed to 300 cGy proton (1 GeV/n) radiation or 50 cGy iron ion (1 GeV/n) radiation [9]. Two antioxidant formulations were utilized in these studies; an AOX formulation containing the mixture of antioxidant agents developed from our previous studies and an antioxidant dietary formulation containing the soybean-derived protease inhibitor known as the Bowman-Birk inhibitor (BBI). BBI was evaluated in the form of BBI Concentrate (BBIC), which is the form of BBI utilized in human trials. BBIC has been utilized in human trials since 1992, as described [10]. The major finding in the long-term animal studies was that there was a reduced risk of malignant lymphoma in mice exposed to space radiations and maintained on diets containing the antioxidant formulations. In addition, the two different dietary countermeasures also reduced the yields of a variety of different rare tumor types, arising from both epithelial and connective tissue cells, observed in the animals exposed to space radiation. REFERENCES [1] Guan J. et al (2004) Radiation Research 162, 572-579. [2] Wan X.S. et al (2005) Radiation Research 163, 364-368. [3] Wan X.S. et al (2005) Radiation Research 163, 232-240. [4] Guan J. et al (2006) Radiation Research 165, 373-378. [5] Wan X.S. et al (2006) International Journal of Radiation Oncology, Biology, Physics 64, 1475-1481. [6] Kennedy A.R. et al (2006) Radiation Research 166, 327-332. [7] Kennedy A.R. et al (2007) Radiation & Environmental Biophysics 46(2), 201-3. [8]Wambi, C., Sanzari, J., Wan, X.S., Nuth, M., Davis, J., Ko, Y.-H., Sayers, C.M., Baran, M., Ware, J.H. and Kennedy, A

Kennedy, Ann

222

Targets for, and consequences of, radiation-induced chromosomal instability  

NASA Astrophysics Data System (ADS)

Chromosomal instability has been demonstrated in a human- hamster hybrid cell line, GM10115, after exposure to x- rays. Chromosomal instability in these cells is characterized by the appearance of novel chromosomal rearrangements multiple generations after exposure to ionizing radiation. To identify the cellular target(s) for radiation-induced chromosomal instability, cells were treated with 125I-labeled compounds. Labeling cells with 125I-iododeoxyuridine, which caused radiation damage to the DNA and associated nuclear structures, did induce chromosomal instability. While cell killing and first-division chromosomal rearrangements increased with increasing numbers of 125I decays, the frequency of chromosomal instability was independent of dose. Incorporation of an 125I-labeled protein, 125I-succinyl- concanavalin A, into either the plasma membrane or the cytoplasm, failed to elicit chromosomal instability. These results show that radiation damage to the nucleus, and not to extranuclear regions, contributes to the induction of chromosomal instability. To determine the role of DNA strand breaks as a molecular lesion responsible for initiating chromosomal instability, cells were treated with a variety of DNA strand breaking agents. Agents capable of producing complex DNA double strand breaks, including X-rays, Neocarzinostatin and bleomycin, were able to induce chromosomal instability. In contrast, double strand breaks produced by restriction endonucleases as well as DNA strand breaks produced by hydrogen peroxide failed to induce chromosomal instability. This demonstrates that the type of DNA breakage is important in the eventual manifestation of chromosomal instability. In order to understand the relationship between chromosomal instability and other end points of genomic instability, chromosomally stable and unstable clones were analyzed for sister chromatid exchange, delayed reproductive cell death, delayed mutation, mismatch repair and delayed gene amplification. Although individual clones within each group were significantly different from unirradiated clones for many of the endpoints, there was no significant correlation between chromosomal instability and the phenotypes of sister chromatid exchange, delayed mutation, and mismatch repair. Delayed gene amplification weakly correlated chromosomal instability (0.05 < p < 0.1) and delayed reproductive cell death correlated strongly (p < 0.05) with chromosomal instability. These data indicate that multiple pathways exist for inducing genomic instability in GM10115 cells after radiation exposure.

Kaplan, Mark Isaac

223

Ionizing Radiation-Induced Cataract in Interventional Cardiology Staff  

PubMed Central

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

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

2015-01-01

224

Radiation Induced Bystander Effects in Mice Given Low Doses of Radiation in Vivo  

PubMed Central

The ‘bystander effect’ phenomenon has challenged the traditional framework for assessing radiation damage by showing radiation induced changes in cells which have not been directly targeted, but are neighbors to or receive medium from directly hit cells. Our group performed a range of single and serial low dose irradiations on two genetically distinct strains of mice. Bladder explants established from these mice were incubated in culture medium, which was used to measure death responses in a keratinocyte reporter system. The study revealed that the medium harvested from bladder tissues’ (ITCM) from acutely irradiated C57BL6 but not Balb/c mice, was able to induce clonogenic death. Administration of a priming dose(s) before a challenge dose to both C57BL6 and Balb/c mice stimulated reporter cell survival irrespective of the time interval between dose(s) delivery. When ITCM corresponding to both strains of mice was measured for its calcium mobilization inducing ability, results showed an elevation in intracellular calcium levels that was strain dependent. This indicates that genotype determined the type of bystander signal/response that was produced after exposure to low and acute doses of radiation. However, serial exposure conditions modified bystander signal production to induce similar effects that were characterized by excessive growth. PMID:21731538

Singh, Harleen; Saroya, Rohin; Smith, Richard; Mantha, Rebecca; Guindon, Lynda; Mitchel, Ron E.J.; Seymour, Colin; Mothersill, Carmel

2010-01-01

225

Radiation-Induced Leukemia at Doses Relevant to Radiation Therapy: Modeling Mechanisms and Estimating Risks  

NASA Technical Reports Server (NTRS)

Because many cancer patients are diagnosed earlier and live longer than in the past, second cancers induced by radiation therapy have become a clinically significant issue. An earlier biologically based model that was designed to estimate risks of high-dose radiation induced solid cancers included initiation of stem cells to a premalignant state, inactivation of stem cells at high radiation doses, and proliferation of stem cells during cellular repopulation after inactivation. This earlier model predicted the risks of solid tumors induced by radiation therapy but overestimated the corresponding leukemia risks. Methods: To extend the model to radiation-induced leukemias, we analyzed in addition to cellular initiation, inactivation, and proliferation a repopulation mechanism specific to the hematopoietic system: long-range migration through the blood stream of hematopoietic stem cells (HSCs) from distant locations. Parameters for the model were derived from HSC biologic data in the literature and from leukemia risks among atomic bomb survivors v^ ho were subjected to much lower radiation doses. Results: Proliferating HSCs that migrate from sites distant from the high-dose region include few preleukemic HSCs, thus decreasing the high-dose leukemia risk. The extended model for leukemia provides risk estimates that are consistent with epidemiologic data for leukemia risk associated with radiation therapy over a wide dose range. For example, when applied to an earlier case-control study of 110000 women undergoing radiotherapy for uterine cancer, the model predicted an excess relative risk (ERR) of 1.9 for leukemia among women who received a large inhomogeneous fractionated external beam dose to the bone marrow (mean = 14.9 Gy), consistent with the measured ERR (2.0, 95% confidence interval [CI] = 0.2 to 6.4; from 3.6 cases expected and 11 cases observed). As a corresponding example for brachytherapy, the predicted ERR of 0.80 among women who received an inhomogeneous low-dose-rate dose to the bone marrow (mean = 2.5 Gy) was consistent with the measured ERR (0.62, 95% Cl =-0.2 to 1.9). Conclusions: An extended, biologically based model for leukemia that includes HSC initiation, inactivation, proliferation, and, uniquely for leukemia, long-range HSC migration predicts, %Kith reasonable accuracy, risks for radiationinduced leukemia associated with exposure to therapeutic doses of radiation.

Shuryak, Igor; Sachs, Rainer K.; Hlatky, Lynn; Mark P. Little; Hahnfeldt, Philip; Brenner, David J.

2006-01-01

226

Radiation induced genome instability: multiscale modelling and data analysis  

NASA Astrophysics Data System (ADS)

Genome instability (GI) is thought to be an important step in cancer induction and progression. Radiation induced GI is usually defined as genome alterations in the progeny of irradiated cells. The aim of this report is to demonstrate an opportunity for integrative analysis of radiation induced GI on the basis of multiscale modelling. Integrative, systems level modelling is necessary to assess different pathways resulting in GI in which a variety of genetic and epigenetic processes are involved. The multilevel modelling includes the Monte Carlo based simulation of several key processes involved in GI: DNA double strand breaks (DSBs) generation in cells initially irradiated as well as in descendants of irradiated cells, damage transmission through mitosis. Taking the cell-cycle-dependent generation of DNA/chromosome breakage into account ensures an advantage in estimating the contribution of different DNA damage response pathways to GI, as to nonhomologous vs homologous recombination repair mechanisms, the role of DSBs at telomeres or interstitial chromosomal sites, etc. The preliminary estimates show that both telomeric and non-telomeric DSB interactions are involved in delayed effects of radiation although differentially for different cell types. The computational experiments provide the data on the wide spectrum of GI endpoints (dicentrics, micronuclei, nonclonal translocations, chromatid exchanges, chromosome fragments) similar to those obtained experimentally for various cell lines under various experimental conditions. The modelling based analysis of experimental data demonstrates that radiation induced GI may be viewed as processes of delayed DSB induction/interaction/transmission being a key for quantification of GI. On the other hand, this conclusion is not sufficient to understand GI as a whole because factors of DNA non-damaging origin can also induce GI. Additionally, new data on induced pluripotent stem cells reveal that GI is acquired in normal mature cells during genome reprogramming by the oncogene c-myc and three additional transcription factors. These and other data reveal the need for generalisation of current model of GI. One can expect that different early events of both DNA damaging and non-damaging origins merge in a single late pathway. To search for a deeper view we propose to redefine GI as genome destabilisation manifested in erosion of genome states and altered transitions between states. This changing view on GI may help to integrate the inducing factors of various origins in the single basic model of GI.

Andreev, Sergey; Eidelman, Yuri

2012-07-01

227

Dynamics of the UV-Induced Absorption of Laser Light by Color Centers in Crystalline KY3F10:Ce3+,Yb3+  

NASA Astrophysics Data System (ADS)

A pump-probe method is used to study the dynamics of the destruction of color centers in KY3F10:Ce3+ and KY3F10:Ce3+,Yb3+ crystals by continuous UV radiation and to measure its parameters. The effect of Yb3+ ions in crystalline KY3F10:Ce3+,Yb3+ on the rate of bleaching of color centers in it under exposure to the probe light is studied. Irradiation of KY3F10:Ce3+ and KY3F10:Ce3+,Yb3+ crystals at a wavelength corresponding to an absorption band of a color center accelerates the destruction of the color centers and the reduction of Yb2+ ions to the trivalent state in proportion to the density of the radiation. A model is constructed for the bleaching mechanism that can be used to estimate the ionization cross section of the color centers.

Morozov, O. A.; Naumov, A. K.; Tselisheva, E. Yu.; Lovchev, A. V.; Korableva, S. L.

2014-09-01

228

Method for increased sensitivity of radiation detection and measurement  

DOEpatents

Dose of radiation to which a body of crystalline material has been exposed is measured by exposing the body to optical radiation at a first wavelength, which is greater than about 540 nm, and measuring optical energy emitted from the body by luminescence at a second wavelength, which is longer than the first wavelength. Reduced background is accomplished by more thorough annealing and enhanced radiation induced luminescence is obtained by treating the crystalline material to coalesce primary damage centers into secondary damage centers.

Miller, Steven D. (Richland, WA)

1994-01-01

229

Pharmacological Protection From Radiation {+-} Cisplatin-Induced Oral Mucositis  

SciTech Connect

Purpose: To evaluate if two pharmacological agents, Tempol and D-methionine (D-met), are able to prevent oral mucositis in mice after exposure to ionizing radiation {+-} cisplatin. Methods and Materials: Female C3H mice, {approx}8 weeks old, were irradiated with five fractionated doses {+-} cisplatin to induce oral mucositis (lingual ulcers). Just before irradiation and chemotherapy, mice were treated, either alone or in combination, with different doses of Tempol (by intraperitoneal [ip] injection or topically, as an oral gel) and D-met (by gavage). Thereafter, mice were sacrificed and tongues were harvested and stained with a solution of Toluidine Blue. Ulcer size and tongue epithelial thickness were measured. Results: Significant lingual ulcers resulted from 5 Multiplication-Sign 8 Gy radiation fractions, which were enhanced with cisplatin treatment. D-met provided stereospecific partial protection from lingual ulceration after radiation. Tempol, via both routes of administration, provided nearly complete protection from lingual ulceration. D-met plus a suboptimal ip dose of Tempol also provided complete protection. Conclusions: Two fairly simple pharmacological treatments were able to markedly reduce chemoradiation-induced oral mucositis in mice. This proof of concept study suggests that Tempol, alone or in combination with D-met, may be a useful and convenient way to prevent the severe oral mucositis that results from head-and-neck cancer therapy.

Cotrim, Ana P. [Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD (United States); Yoshikawa, Masanobu [Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD (United States); Department of Clinical Pharmacology, Tokai University School of Medicine, Kanagawa (Japan); Sunshine, Abraham N.; Zheng Changyu [Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD (United States); Sowers, Anastasia L.; Thetford, Angela D.; Cook, John A.; Mitchell, James B. [Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD (United States); Baum, Bruce J., E-mail: bbaum@dir.nidcr.nih.gov [Molecular Physiology and Therapeutics Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD (United States)

2012-07-15

230

Microbiota and radiation-induced bowel toxicity: lessons from inflammatory bowel disease for the radiation oncologist.  

PubMed

New gastrointestinal symptoms are frequent after pelvic radiotherapy and can greatly affect the quality of life of cancer survivors. The effect of radiation on the intestinal microbiota, and the clinical implications of a modified microbial balance after radiotherapy are now beginning to emerge. In this Personal View, we show the importance of the microbiota for intestinal homoeostasis, and discuss the similarity between inflammatory bowel disease, which has been extensively researched, and radiation-induced gastrointestinal toxicity. By use of microbiota profiles for risk assessment and manipulation of the intestinal flora for prevention and treatment of radiation, enteropathy could become a reality and would be of substantial relevance to the increasing numbers of long-term cancer survivors. PMID:24599929

Ferreira, Miguel R; Muls, Ann; Dearnaley, David P; Andreyev, H Jervoise N

2014-03-01

231

Radiation Induces Osteogenesis in Human Aortic Valve Interstitial Cells  

PubMed Central

Objective Irradiation of the chest or chest wall has been shown to caause calcific aortic stenosis. However, the mechanisms are unknown. Aortic valve interstitial cells (AVICs) have been implicated in the pathogenesis of aortic stenosis; they have been shown to change from the phenotype of a myofibroblast to an osteoblast-like cell. We therefore hypothesized that irradiation of human AVICs induces an osteogenic phenotype. In isolated human AVICs, our purpose was to determine the effect of irradiation on the production of osteogenic factors: (a) bone morphogenetic protein-2 (BMP-2) (b) osteopontin (OPN) (c) alkaline phosphatase (ALP), and (d) the transcription factor Runx2. Methods Human AVICs were isolated from normal aortic valves obtained from explanted hearts of patients undergoing cardiac transplantation (n=4) and grown in culture. The cells were grown to confluence, irradiated with 10 Gy using a cesium-137 irradiator and then lysed 24 hours following irradiation. Cell lysates were analyzed via immunoblot and densitometry for BMP-2, OPN, ALP and Runx2. Statistics were by ANOVA. P < 0.05 was significant. Results Irradiation induced an osteogenic phenotype in human AVICs. Irradiation induced a 2-fold increase in BMP-2, a 7-fold increase in OPN, a 3-fold increase in ALP, and a 2-fold increase in Runx2. Conclusions Radiation induces an osteogenic phenotype in human AVICs. The irradiated cells had significantly increased expression of the osteogenic factors BMP-2, OPN, ALP and Runx2. These data offer mechanistic insight into the pathogenesis of radiation-induced valvular heart disease. PMID:23026565

Nadlonek, Nicole A; Weyant, Michael J; Yu, Jessica A; Cleveland, Joseph C; Reece, T Brett; Meng, Xianzhong; Fullerton, David A.

2012-01-01

232

Cerenkov emission induced by external beam radiation stimulates molecular fluorescence  

SciTech Connect

Purpose: Cerenkov emission is induced when a charged particle moves faster than the speed of light in a given medium. Both x-ray photons and electrons produce optical Cerenkov photons in everyday radiation therapy of tissue; yet, this phenomenon has never been fully documented. This study quantifies the emissions and also demonstrates that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Methods: In this study, Cerenkov emission induced by radiation from a clinical linear accelerator is investigated. Biological mimicking phantoms were irradiated with x-ray photons, with energies of 6 or 18 MV, or electrons at energies 6, 9, 12, 15, or 18 MeV. The Cerenkov emission and the induced molecular fluorescence were detected by a camera or a spectrometer equipped with a fiber optic cable. Results: It is shown that both x-ray photons and electrons, at MeV energies, produce optical Cerenkov photons in tissue mimicking media. Furthermore, we demonstrate that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Conclusions: The results here indicate that molecular fluorescence monitoring during external beam radiotherapy is possible.

Axelsson, Johan; Davis, Scott C.; Gladstone, David J.; Pogue, Brian W. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States); Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)

2011-07-15

233

Hippocampal lesions induced by ionizing radiation: a parametric study.  

PubMed

The selective lesion of granule cell populations in the dentate gyrus induced by ionizing radiation has been proposed as a useful method for evaluating the effects of hippocampal lesions on behavioral tasks. In the first part of the present study we confirmed the induction of the selective lesion of hippocampal dentate gyrus by ionizing radiation in infant Wistar rats, reported previously, but to a smaller extent with less cell loss. A parametric study was thus performed to assess the effect of modification of the parameters previously tested, comprising three further steps: an increase in the total dose of X-rays and modification of the fractionating schedule; use of three radiation types, X-ray, gamma-ray, and electrons (at two energy levels, 3 and 7 mev); use of three X-ray energy levels, 180, 200 and 250 kVp; and assessment of the effect of five total X-ray doses, at 200 kVp, 10, 14, 16, 18 and 20 gy (grays). The data suggests that X-ray radiation, in a total dose of 14 gy, at the 200 kVp energy level, fractionated into seven consecutive exposures of 2 gy each and produces a lesion of about 85% of the dentate gyrus granule cells. PMID:9262142

Moreira, R C; Moreira, M V; Bueno, J L; Xavier, G F

1997-07-18

234

Solar radiation induced rotational bursting of interplanetary particles  

NASA Technical Reports Server (NTRS)

It is suggested that the magnitudes of the two radiation-induced rotational bursting mechanisms (Radzieskii effect and windmill effect) have been overestimated and that they do not work significantly faster than the Poynting-Robertson effect in removing interplanetary particles. These two mechanisms are described, and serious doubts are raised regarding the derivation of their radiation pressure-torque proportionality constants, which are required for calculating their magnitudes. It is shown that both mechanisms will cause the alignment of elongated particles and, consequently, the polarization of zodiacal light. Since no positive polarization has been measured at the antisolar point, it is concluded that the magnitudes of the rotational bursting mechanisms are smaller than that of the Poynting-Robertson effect.

Sparrow, J. G.

1975-01-01

235

Genomic Instability Induced by High and Low Let Ionizing Radiation  

NASA Astrophysics Data System (ADS)

Genomic instability is the increased rate of acquisition of alterations in the mammalian genome, and includes such diverse biological endpoints as chromosomal destabilization, aneuploidy, micronucleus formation, sister chromatid exchange, gene mutation and amplification, variations in colony size, reduced plating efficiency, and cellular transformation. Because these multiple endpoints persist long after initial radiation exposure, genomic instability has been proposed to operate as a driving force contributing to genetic plasticity and carcinogenic potential. Many of these radiation-induced endpoints depend qualitatively and quantitatively on genetic background, dose and LET. Differences in the frequency and temporal expression of chromosomal instability depend on all three of the foregoing factors. On the other hand, many of these endpoints appear independent of dose and show bystander effects, implicating non-nuclear targets and epigenetic regulatory mechanisms. The present work will survey results concerning the LET dependence of genomic instability and the role of epigenetic mechanisms, with a particular emphasis on the endpoint of chromosomal in tability

Limoli, C. L.; Ponnaiya, B.; Corcoran, J. J.; Giedzinski, E.; Kaplan, M. I.; Hartmann, A.; Morgan, W. F.

236

Radiation-induced transient absorption in optical fibers  

SciTech Connect

Transient absorption in optical fibers has been studied with emphasis on fast absorption components. Radiation damage was induced with a Febetron 706 electron accelerator, modified to deliver an electron pulse width of 1.1 ns. Dye lasers were synchronized to the accelerator to provide a light pulse through the fiber during the radiation pulse. The output light pulse was detected with a biplanar vacuum photodiode. Four scope traces were used on each electron pulse to monitor the Febetron output, the input drive pulse, and two records of the output pulse on two sweep speeds. Detailed data were acquired for times less than 100 ns after irradiation. An insulated enslosure was used to vary fiber temperature from -30/sup 0/C to + 250/sup 0/C. Several fibers were studied with emphasis on ITT T303 PCS fiber. Data were acquired at 600 and 850 nm. Theoretical modeling of the data is presented.

Looner, L.D.; Turquet de Beauregard, G.; Lyons, P.B.; Kelly, R.E.

1981-01-01

237

Treatment of radiation- and chemotherapy-induced stomatitis  

SciTech Connect

Severe stomatitis is a common problem encountered during either radiation therapy or chemotherapy. Most therapeutic regimens are empirical, with no scientific basis. The purpose of this study is to determine the efficacy of various topical solutions in the treatment of radiation- or chemotherapy-induced stomatitis. Eighteen patients were entered into a prospective double-blinded study to test several topical solutions: (1) viscous lidocaine with 1% cocaine; (2) dyclonine hydrochloride 1.0% (Dyclone); (3) kaolin-pectin solution, diphenhydramine plus saline (KBS); and (4) a placebo solution. Degree of pain relief, duration of relief, side effects, and palatability were evaluated. The results showed that Dyclone provided the most pain relief. Dyclone and viscous lidocaine with 1% cocaine provided the longest pain relief, which averaged 50 minutes This study provides objective data and defines useful guidelines for treatment of stomatitis.

Carnel, S.B.; Blakeslee, D.B.; Oswald, S.G.; Barnes, M. (Fitzsimons Army Medical Center, Aurora, CO (USA))

1990-04-01

238

The role of continuum radiation in laser induced plasma spectroscopy  

NASA Astrophysics Data System (ADS)

This paper focuses on the interpretation of the origin of the continuum radiation in Laser Induced Plasma (LIP) emission spectra, a subject that has received little consideration in the literature when compared to the analysis of the line emission spectrum. The understanding of the spectral peculiarities observed immediately after the laser pulse, when the continuum radiation prevails on discrete emission lines, can be extremely important to retrieve the initial conditions of LIP and to correlate the produced plasma to the ablation mechanism. In this work, in addition to a qualitative interpretation of the LIP continuum in the initial stage of expansion, a methodology is proposed for a better measurement of the atomic temperature in the expansion stage of the LIP. Such methodology is based on the analysis of the combined Boltzmann and Planck plots. The results obtained stress once again the importance of considering non equilibrium effects in the initial stage of LIP expansion.

De Giacomo, A.; Gaudiuso, R.; Dell'Aglio, M.; Santagata, A.

2010-05-01

239

Method and apparatus for characterization of electric field-induced aggregation in pre-crystalline protein solutions  

NASA Astrophysics Data System (ADS)

The article presents a method and an apparatus for the characterization of protein aggregation under an applied internal electric field. The method is based on a forward light scattering technique that is highly sensitive to aggregates in pre-crystalline protein solutions. Transparent conductive films are used as electrodes for a planar thin sample cell, which enables precise measurement of the forward light scattering at small angles through the electrodes. Evaluation of the protein aggregation under applied electric fields was demonstrated for a model lysozyme protein. In situ measurements of crystallizing lysozyme solutions under a low applied voltage revealed that the forward static light scattering profiles changed with time into power law profiles. This indicates the formation of lysozyme fractal clusters under applied electric fields in the pre-crystalline state. The method and the apparatus presented here can sensitively evaluate the promotion process in protein crystallization under an applied electric field.

Wakamatsu, Takashi

2015-01-01

240

Shock-induced changes in density and porosity in shock-metamorphosed crystalline rocks, Haughton impact structure, Canada  

NASA Astrophysics Data System (ADS)

Shock metamorphism can occur at transient pressures that reach tens of GPa and well over 1000 °C, altering the target material on both megascopic and microscopic scales. This study explores the effects of shock metamorphism on crystalline, quartzofeldspathic basement material from the Haughton impact structure on Devon Island, Arctic Canada. Shock levels were assigned to samples based on petrographic examination of main mineral phases. Conventional shock classification schemes proved to incompletely describe the Haughton samples so a modified shock classification system is presented. Fifty-two crystalline bedrock samples from the clast-rich impact melt rocks in the crater, and one reference site outside of the crater, were classified using this system. The shock levels range from 0 to 7 (according to the new shock stage classification proposed here, i.e., stages 0-IV after the Stöffler classification), indicating shock pressures ranging from 0 to approximately 80 GPa. The second aspect of this study involved measuring bulk physical characteristics of the shocked samples. The bulk density, grain density, and porosity were determined using a water displacement method, a bead displacement method, and a Hepycnometer. Results suggest a nonlinear, negative correlation between density and shock level such that densities of crystalline rocks with original densities of approximately 3 g cm-3 are reduced to <1.0 g cm-3 at high shock levels. The results also show a positive nonlinear correlation between porosity and shock level. These data illustrate the effect of shock on the bulk physical characteristics of crystalline rocks, and has implications for assessing the habitability of shocked rocks.

Singleton, Alaura C.; Osinski, Gordon R.; McCausland, Phil J. A.; Moser, Desmond E.

2011-11-01

241

?-Tocopherol succinate protects mice against radiation-induced gastrointestinal injury.  

PubMed

The purpose of this study was to elucidate the role of ?-tocopherol succinate (?-TS) in protecting mice from gastrointestinal syndrome induced by total-body irradiation. CD2F1 mice were injected subcutaneously with 400 mg/kg of ?-TS and exposed to different doses of (60)Co ? radiation, and 30-day survival was monitored. Jejunum sections were analyzed for crypts and villi, PUMA (p53 upregulated modulator of apoptosis), and apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling - TUNEL). The crypt regeneration in irradiated mice was evaluated by 5-bromo-2-deoxyuridine (BrdU). Bacterial translocation from gut to heart, spleen and liver in ?-TS-treated and irradiated mice was evaluated by bacterial culture on sheep blood agar, colistin-nalidixic acid, and xylose-lysine-desoxycholate medium. Our results demonstrate that ?-TS enhanced survival in a significant number of mice irradiated with 9.5, 10, 11 and 11.5 Gy (60)Co ? radiation when administered 24 h before radiation exposure. ?-TS also protected the intestinal tissue of irradiated mice in terms of crypt and villus number, villus length and mitotic figures. TS treatment decreased the number of TUNEL- and PUMA-positive cells and increased the number of BrdU-positive cells in jejunum compared to vehicle-treated mice. Further, ?-TS inhibited gut bacterial translocation to the heart, spleen and liver in irradiated mice. Our data suggest that ?-TS protects mice from radiation-induced gastrointestinal damage by inhibiting apoptosis, promoting regeneration of crypt cells, and inhibiting translocation of gut bacteria. PMID:22013885

Singh, Pankaj K; Wise, Stephen Y; Ducey, Elizabeth J; Fatanmi, Oluseyi O; Elliott, Thomas B; Singh, Vijay K

2012-02-01

242

Erythrocyte Stiffness during Morphological Remodeling Induced by Carbon Ion Radiation  

PubMed Central

The adverse effect induced by carbon ion radiation (CIR) is still an unavoidable hazard to the treatment object. Thus, evaluation of its adverse effects on the body is a critical problem with respect to radiation therapy. We aimed to investigate the change between the configuration and mechanical properties of erythrocytes induced by radiation and found differences in both the configuration and the mechanical properties with involving in morphological remodeling process. Syrian hamsters were subjected to whole-body irradiation with carbon ion beams (1, 2, 4, and 6 Gy) or X-rays (2, 4, 6, and 12 Gy) for 3, 14 and 28 days. Erythrocytes in peripheral blood and bone marrow were collected for cytomorphological analysis. The mechanical properties of the erythrocytes were determined using atomic force microscopy, and the expression of the cytoskeletal protein spectrin-?1 was analyzed via western blotting. The results showed that dynamic changes were evident in erythrocytes exposed to different doses of carbon ion beams compared with X-rays and the control (0 Gy). The magnitude of impairment of the cell number and cellular morphology manifested the subtle variation according to the irradiation dose. In particular, the differences in the size, shape and mechanical properties of the erythrocytes were well exhibited. Furthermore, immunoblot data showed that the expression of the cytoskeletal protein spectrin-?1 was changed after irradiation, and there was a common pattern among its substantive characteristics in the irradiated group. Based on these findings, the present study concluded that CIR could induce a change in mechanical properties during morphological remodeling of erythrocytes. According to the unique characteristics of the biomechanical categories, we deduce that changes in cytomorphology and mechanical properties can be measured to evaluate the adverse effects generated by tumor radiotherapy. Additionally, for the first time, the current study provides a new strategy for enhancing the assessment of the curative effects and safety of clinical radiotherapy, as well as reducing adverse effects. PMID:25401336

Zhang, Baoping; Liu, Bin; Zhang, Hong; Wang, Jizeng

2014-01-01

243

Radiation-induced chromosomal aberrations at different dose-rates  

E-print Network

the damage is not observable since the cells are in the interphase stage of mitosis, snd the manifestations of liver injury may be delayed until such time that the cells may enter mitoses. Cytological observations of radiation-induced mitotic aber... are in the radiosensitive state at the time of irradiation or does the injury remain latent until such time as the cells may enter the critical phase. In the testes, a rapidly dividing tissue, the results of irradiation are isamdiately manifested whereas in the liver...

McDaniel, Jackson Dean

1965-01-01

244

Measurements of prompt radiation induced conductivity in Teflon (PTFE).  

SciTech Connect

We performed measurements of the prompt radiation induced conductivity (RIC) in thin samples of Teflon (PTFE) at the Little Mountain Medusa LINAC facility in Ogden, UT. Three mil (76.2 microns) samples were irradiated with a 0.5 %CE%BCs pulse of 20 MeV electrons, yielding dose rates of 1E9 to 1E11 rad/s. We applied variable potentials up to 2 kV across the samples and measured the prompt conduction current. Details of the experimental apparatus and analysis are reported in this report on prompt RIC in Teflon.

Hartman, E. Frederick; Zarick, Thomas Andrew; Sheridan, Timothy J.; Preston, E. [ITT Exelis Mission Systems, Colorado Springs, CO

2013-05-01

245

Measurements of prompt radiation induced conductivity of Kapton.  

SciTech Connect

We performed measurements of the prompt radiation induced conductivity in thin samples of Kapton (polyimide) at the Little Mountain Medusa LINAC facility in Ogden, UT. Three mil samples were irradiated with a 0.5 {mu}s pulse of 20 MeV electrons, yielding dose rates of 1E9 to 1E10 rad/s. We applied variable potentials up to 2 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 6E-17 and 2E-16 mhos/m per rad/s, depending on the dose rate and the pulse width.

Preston, Eric F. (ITT Corporation, Colorado Springs, CO); Zarick, Thomas Andrew; Sheridan, Timothy J.; Hartman, E. Frederick; Stringer, Thomas Arthur (ITT Corporation, Colorado Springs, CO)

2010-10-01

246

Facial reconstruction for radiation-induced skin cancer  

SciTech Connect

Radiation-induced skin cancers can be difficult to diagnose and treat. Typically, a patient who has received orthovoltage radiotherapy for disorders such as acne, eczema, tinea capitis, skin tuberculosis, and skin cancer can expect that aggressive skin cancers and chronic radiodermatitis may develop subsequently. Cryptic facial cancers can lead to metastases and death. Prophylactic widefield excision of previously irradiated facial skin that has been subject to multiple recurrent skin cancers is suggested as a method of deterring future cutaneous malignancy and metastases. The use of tissue expanders and full-thickness skin grafts offers an expedient and successful method of subsequent reconstruction.

Panje, W.R.; Dobleman, T.J. (Univ. of Chicago, IL (USA))

1990-04-01

247

Heat Induced Damage Detection by Terahertz (THz) Radiation  

NASA Astrophysics Data System (ADS)

Terahertz (THz) and sub-terahertz imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques for damage detection and characterization of materials. THz radiation is being used for inspecting ceramic foam tiles used in TPS (Thermal Protection System), thick polymer composites and polymer tiles that are not good conductors of ultrasonic waves. Capability of THz electromagnetic waves in detecting heat induced damage in porous materials is investigated in this paper. Porous pumice stone blocks are subjected to long time heat exposures to produce heat induced damage in the block. The dielectric properties extracted from THz TDS (Time Domain Spectroscopy) measurements are compared for different levels of heat exposure. Experimental results show noticeable and consistent change in dielectric properties with increasing levels of heat exposure, well before its melting point.

Rahani, Ehsan Kabiri; Kundu, Tribikram; Wu, Ziran; Xin, Hao

2011-06-01

248

Pressure-induced superconducting state in crystalline boron nanowires Liling Sun,1,*, Takahiro Matsuoka,2 Yasuyuki Tamari,2 Katsuya Shimizu,2,*, Jifa Tian,1 Yuan Tian,1 Chendong Zhang,1  

E-print Network

Pressure-induced superconducting state in crystalline boron nanowires Liling Sun,1,*, Takahiro February 2009; published 16 April 2009 We report high-pressure induced superconductivity in boron nanowires-B , these BNWs show a semiconductor- metal transition at much lower pressure than bulk -r-B. Also, we found

Gao, Hongjun

249

Galactic cosmic ray-induced radiation dose on terrestrial exoplanets.  

PubMed

This past decade has seen tremendous advancements in the study of extrasolar planets. Observations are now made with increasing sophistication from both ground- and space-based instruments, and exoplanets are characterized with increasing precision. There is a class of particularly interesting exoplanets that reside in the habitable zone, which is defined as the area around a star where the planet is capable of supporting liquid water on its surface. Planetary systems around M dwarfs are considered to be prime candidates to search for life beyond the Solar System. Such planets are likely to be tidally locked and have close-in habitable zones. Theoretical calculations also suggest that close-in exoplanets are more likely to have weaker planetary magnetic fields, especially in the case of super-Earths. Such exoplanets are subjected to a high flux of galactic cosmic rays (GCRs) due to their weak magnetic moments. GCRs are energetic particles of astrophysical origin that strike the planetary atmosphere and produce secondary particles, including muons, which are highly penetrating. Some of these particles reach the planetary surface and contribute to the radiation dose. Along with the magnetic field, another factor governing the radiation dose is the depth of the planetary atmosphere. The higher the depth of the planetary atmosphere, the lower the flux of secondary particles will be on the surface. If the secondary particles are energetic enough, and their flux is sufficiently high, the radiation from muons can also impact the subsurface regions, such as in the case of Mars. If the radiation dose is too high, the chances of sustaining a long-term biosphere on the planet are very low. We have examined the dependence of the GCR-induced radiation dose on the strength of the planetary magnetic field and its atmospheric depth, and found that the latter is the decisive factor for the protection of a planetary biosphere. PMID:24143867

Atri, Dimitra; Hariharan, B; Grießmeier, Jean-Mathias

2013-10-01

250

In-Situ Measurement of Crystalline Silicon Modules Undergoing Potential-Induced Degradation in Damp Heat Stress Testing for Estimation of Low-Light Power Performance  

SciTech Connect

The extent of potential-induced degradation of crystalline silicon modules in an environmental chamber is estimated using in-situ dark I-V measurements and applying superposition analysis. The dark I-V curves are shown to correctly give the module power performance at 200, 600 and 1,000 W/m2 irradiance conditions, as verified with a solar simulator. The onset of degradation measured in low light in relation to that under one sun irradiance can be clearly seen in the module design examined; the time to 5% relative degradation measured in low light (200 W/m2) was 28% less than that of full sun (1,000 W/m2 irradiance). The power of modules undergoing potential-induced degradation can therefore be characterized in the chamber, facilitating statistical analyses and lifetime forecasting.

Hacke, P.; Terwilliger, K.; Kurtz, S.

2013-08-01

251

Follistatin Is Induced by Ionizing Radiation and Potentially Predictive of Radiosensitivity in Radiation-Induced Fibrosis Patient Derived Fibroblasts  

PubMed Central

Follistatin is a potent regulator of the inflammatory response and binds to and inhibits activin A action. Activin A is a member of the TGF? protein superfamily which has regulatory roles in the inflammatory response and in the fibrotic process. Fibrosis can occur following cell injury and cell death induced by agents such as ionizing radiation (IR). IR is used to treat cancer and marked fibrotic response is a normal tissue (non-tumour) consequence in a fraction of patients under the current dose regimes. The discovery and development of a therapeutic to abate fibrosis in these radiosensitive patients would be a major advance for cancer radiotherapy. Likewise, prediction of which patients are susceptible to fibrosis would enable individualization of treatment and provide an opportunity for pre-emptive fibrosis control and better tumour treatment outcomes. The levels of activin A and follistatin were measured in fibroblasts derived from patients who developed severe radiation-induced fibrosis following radiotherapy and compared to fibroblasts from patients who did not. Both follistatin and activin A gene expression levels were increased following IR and the follistatin gene expression level was lower in the fibroblasts from fibrosis patients compared to controls at both basal levels and after IR. The major follistatin transcript variants were found to have a similar response to IR and both were reduced in fibrosis patients. Levels of follistatin and activin A secreted in the fibroblast culture medium also increased in response to IR and the relative follistatin protein levels were significantly lower in the samples derived from fibrosis patients. The decrease in the follistatin levels can lead to an increased bioactivity of activin A and hence may provide a useful measurement to identify patients at risk of a severe fibrotic response to IR. Additionally, follistatin, by its ability to neutralise the actions of activin A may be of value as an anti-fibrotic for radiation induced fibrosis. PMID:24204752

McKay, Michael J.; Leong, Trevor; de Kretser, David M.; Sprung, Carl N.

2013-01-01

252

Space-radiation-induced Photon Luminescence of the Moon  

NASA Technical Reports Server (NTRS)

We report on the results of a study of the photon luminescence of the Moon induced by Galactic Cosmic Rays (GCRs) and space radiation from the Sun, using the Monte Carlo program FLUKA. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) above 1 keV in FLUKA to determine the photon fluence albedo produced by the Moon's surface when there is no sunlight and Earthshine. This is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of radiogenic constituents lying in the surface and interior of the Moon. From the photon fluence we derive the spectrum which can be utilized to examine existing lunar spectral data and to design orbiting instrumentation for measuring various components of the space-radiation-induced photon luminescence present on the Moon.

Wilson, Thomas; Lee, Kerry

2008-01-01

253

Radiation-induced alterations in histone modification patterns and their potential impact on short-term radiation effects  

PubMed Central

Detection and repair of radiation-induced DNA damage occur in the context of chromatin. An intricate network of mechanisms defines chromatin structure, including DNA methylation, incorporation of histone variants, histone modifications, and chromatin remodeling. In the last years it became clear that the cellular response to radiation-induced DNA damage involves all of these mechanisms. Here we focus on the current knowledge on radiation-induced alterations in post-translational histone modification patterns and their effect on the chromatin accessibility, transcriptional regulation and chromosomal stability. PMID:23050241

Friedl, Anna A.; Mazurek, Belinda; Seiler, Doris M.

2012-01-01

254

UVB radiation induced effects on cells studied by FTIR spectroscopy  

E-print Network

We have made a preliminary analysis of the results about the eVects on tumoral cell line (lymphoid T cell line Jurkat) induced by UVB radiation (dose of 310 mJ/cm^2) with and without a vegetable mixture. In the present study, we have used two techniques: Fourier transform infrared spectroscopy (FTIR) and flow cytometry. FTIR spectroscopy has the potential to provide the identiWcation of the vibrational modes of some of the major compounds (lipid, proteins and nucleic acids) without being invasive in the biomaterials. The second technique has allowed us to perform measurements of cytotoxicity and to assess the percentage of apoptosis. We already studied the induction of apoptotic process in the same cell line by UVB radiation; in particular, we looked for correspondences and correlations between FTIR spetroscopy and flow cytometry data finding three highly probable spectroscopic markers of apoptosis (Pozzi et al. in Radiat Res 168:698-705, 2007). In the present work, the results have shown significant changes ...

Di Giambattista, Lucia; Gaudenzi, S; Pozzi, D; Grandi, M; Morrone, S; Silvestri, I; Castellano, A Congiu; 10.1007/s00249-009-0446-9

2010-01-01

255

Proton-induced radiation damage in germanium detectors  

NASA Technical Reports Server (NTRS)

High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process, several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10 to the 8th protons/sq cm (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific and engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation, all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage, the detectors were stepwise-annealed at temperatures below 110 C, while kept in their specially designed cryostats. This study shows that n-type HPGe detectors can be used in charged-particle environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

Brueckner, J.; Koerfer, M.; Waenke, H.; Schroeder, A. N. F.; Filges, D.; Dragovitsch, P.; Englert, P. A. J.; Starr, R.; Trombka, J. I.

1991-01-01

256

Robust Feedback Control of Flow Induced Structural Radiation of Sound  

NASA Technical Reports Server (NTRS)

A significant component of the interior noise of aircraft and automobiles is a result of turbulent boundary layer excitation of the vehicular structure. In this work, active robust feedback control of the noise due to this non-predictable excitation is investigated. Both an analytical model and experimental investigations are used to determine the characteristics of the flow induced structural sound radiation problem. The problem is shown to be broadband in nature with large system uncertainties associated with the various operating conditions. Furthermore the delay associated with sound propagation is shown to restrict the use of microphone feedback. The state of the art control methodologies, IL synthesis and adaptive feedback control, are evaluated and shown to have limited success for solving this problem. A robust frequency domain controller design methodology is developed for the problem of sound radiated from turbulent flow driven plates. The control design methodology uses frequency domain sequential loop shaping techniques. System uncertainty, sound pressure level reduction performance, and actuator constraints are included in the design process. Using this design method, phase lag was added using non-minimum phase zeros such that the beneficial plant dynamics could be used. This general control approach has application to lightly damped vibration and sound radiation problems where there are high bandwidth control objectives requiring a low controller DC gain and controller order.

Heatwole, Craig M.; Bernhard, Robert J.; Franchek, Matthew A.

1997-01-01

257

Radiation induced thyroid neoplasms 1920 to 1987: A vanishing problem  

SciTech Connect

Radiation for benign diseases has been implicated as an etiologic factor in thyroid cancer. From 1930-60, over 2 million children may have been exposed to therapeutic radiation and it is estimated that up to 7% may develop thyroid cancer after a 5-40 year latency. Thyroid stimulating hormone, secondary to radioinduced hypothyroidism, has been implicated as causative in animals. Such data has led to expensive screening programs in high risk patients. Because of a decline in irradiation for benign diseases in children over the last 2 decades, we questioned whether the incidence of radiation induced thyroid neoplasms (RITN) was also decreasing. Twenty-six of 227 patients (11%) with thyroid malignancies seen at our institution from 1974-87 had a history of previous head and neck irradiation. These included 13 papillary, 3 follicular, and 7 mixed carcinomas as well as 2 lymphomas and 1 synovial cell sarcoma. None of these 26 patients had abnormal thyroid function tests at presentation. Mean latency from irradiation to the diagnosis of thyroid cancer was 25.4 years (6-55 year range). Compared to the reported increasing incidence of RITN from 1940-70, there appears to be a significant decrease since 1970. Based on our analysis, the use of expensive screening programs in high risk populations may no longer be warranted. Additionally, the routine use of thyroid replacement in previously irradiated chemically hypothyroid patients is not recommended.30 references.

Mehta, M.P.; Goetowski, P.G.; Kinsella, T.J.

1989-06-01

258

Simultaneous broadband light trapping and fill factor enhancement in crystalline silicon solar cells induced by Ag nanoparticles and nanoshells.  

PubMed

Crystalline silicon solar cells are predominant and occupying more than 89% of the global solar photovoltaic market. Despite the boom of the innovative solar technologies, few can provide a low-cost radical solution to dramatically boost the efficiency of crystalline silicon solar cells, which has reached plateau in the past ten years. Here, we present a novel strategy to simultaneously achieve dramatic enhancement in the short-circuit current and the fill factor through the integration of Ag plasmonic nanoparticles and nanoshells on the antireflection coating and the screen-printed fingers of monocrystalline silicon solar cells, respectively, by a single step and scalable modified electroless displacement method. As a consequence, up to 35.2% enhancement in the energy conversion efficiency has been achieved due to the plasmonic broadband light trapping and the significant reduction in the series resistance. More importantly, this method can further increase the efficiency of the best performing textured solar cells from 18.3% to 19.2%, producing the highest efficiency cells exceeding the state-of-the-art efficiency of the standard screen-printed solar cells. The dual functions of the Ag nanostructures, reported for the first time here, present a clear contrast to the previous works, where plasmonic nanostructures were integrated into solar cells to achieve the short-circuit current enhancement predominately. Our method offers a facile, cost-effective and scalable pathway for metallic nanostructures to be used to dramatically boost the overall efficiency of the optically thick crystalline silicon solar cells. PMID:23037536

Fahim, Narges F; Jia, Baohua; Shi, Zhengrong; Gu, Min

2012-09-10

259

Radiation-induced defects in clay minerals: A review  

NASA Astrophysics Data System (ADS)

Extensive information has been collected on radiation effects on clay minerals over the last 35 years, providing a wealth of information on environmental and geological processes. The fields of applications include the reconstruction of past radioelement migrations, the dating of clay minerals or the evolution of the physico-chemical properties under irradiation. The investigation of several clay minerals, namely kaolinite, dickite, montmorillonite, illite and sudoite, by Electron Paramagnetic Resonance Spectroscopy has shown the presence of defects produced by natural or artificial radiations. These defects consist mostly of electron holes located on oxygen atoms of the structure. The various radiation-induced defects are differentiated through their nature and their thermal stability. Most of them are associated with a ? orbital on a Si-O bond. The most abundant defect in clay minerals is oriented perpendicular to the silicate layer. Thermal annealing indicates this defect in kaolinite (A-center) to be stable over geological periods at ambient temperature. Besides, electron or heavy ion irradiation easily leads to an amorphization in smectites, depending on the type of interlayer cation. The amorphization dose exhibits a bell-shaped variation as a function of temperature, with a decreasing part that indicates the influence of thermal dehydroxylation. Two main applications of the knowledge of radiation-induced defects in clay minerals are derived: (i) The use of defects as tracers of past radioactivity. In geological systems where the age of the clay can be constrained, ancient migrations of radioelements can be reconstructed in natural analogues of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to fault gouges or laterites of the Amazon basin. (ii) The influence of irradiation over physico-chemical properties of clay minerals. An environmental application concerns the performance assessment of the engineered barrier of nuclear waste disposals. In case of a leakage of transuranic elements from the radioactive waste form, alpha recoil nuclei can amorphize smectite after periods of the order of 1000 years according to a worst case scenario, whereas amorphization from ionizing radiation is unlikely. As amorphization greatly enhances the dissolution kinetics of smectite, the sensitivity of the smectites must be taken into account in the prediction of the long term behavior of engineered barriers.

Allard, Th.; Balan, E.; Calas, G.; Fourdrin, C.; Morichon, E.; Sorieul, S.

2012-04-01

260

An amino acid mixture mitigates radiation-induced gastrointestinal toxicity.  

PubMed

Electrolyte and nutrient absorption occur in villous epithelial cells. Radiation often results in reduced electrolyte and nutrient absorption, which leads to gastrointestinal toxicity. Therefore, the authors studied: (1) radiation-induced changes in glucose and amino acid absorption across ileal tissues and (2) the effect of amino acid mixtures on absorptive capacity. NIH Swiss mice were irradiated (0, 1, 3, 5, or 7 Gy) using a ¹³?Cs source at 0.9 Gy min?¹. Transepithelial short circuit current (I(sc)), dilution potential, and isotope flux determinations were made in Ussing chamber studies and correlated to plasma endotoxin and IL-1? levels. Amino acids that increased electrolyte absorption and improved mucosal barrier functions were used to create a mitigating amino acid mixture (MAAM). The MAAM was given to mice via gastric gavage; thereafter, body weight and survival were recorded. A significant decrease in basal and glucose-stimulated sodium absorption occurred after 0, 1, 3, 5, and 7 Gy irradiation. Ussing chamber studies showed that paracellular permeability increased following irradiation and that the addition of glucose resulted in a further increase in permeability. Following irradiation, certain amino acids manifested decreased absorption, whereas others were associated with increased absorption. Lysine, aspartic acid, glycine, isoleucine, threonine, tyrosine, valine, tryptophan, and serine decreased plasma endotoxins were selected for the MAAM. Mice treated with the MAAM showed increased electrolyte absorption and decreased paracellular permeability, IL-1? levels, and plasma endotoxin levels. Mice treated with MAAM also had increased weight gain and better survival following irradiation. The MAAM has immediate potential for use in mitigating radiation-induced acute gastrointestinal syndrome. PMID:24776907

Yin, Liangjie; Vijaygopal, Pooja; Menon, Rejeesh; Vaught, Lauren A; Zhang, Mei; Zhang, Lurong; Okunieff, Paul; Vidyasagar, Sadasivan

2014-06-01

261

Ionizing radiation induces tumor cell lysyl oxidase secretion  

PubMed Central

Background Ionizing radiation (IR) is a mainstay of cancer therapy, but irradiation can at times also lead to stress responses, which counteract IR-induced cytotoxicity. IR also triggers cellular secretion of vascular endothelial growth factor, transforming growth factor ? and matrix metalloproteinases, among others, to promote tumor progression. Lysyl oxidase is known to play an important role in hypoxia-dependent cancer cell dissemination and metastasis. Here, we investigated the effects of IR on the expression and secretion of lysyl oxidase (LOX) from tumor cells. Methods LOX-secretion along with enzymatic activity was investigated in multiple tumor cell lines in response to irradiation. Transwell migration assays were performed to evaluate invasive capacity of naïve tumor cells in response to IR-induced LOX. In vivo studies for confirming IR-enhanced LOX were performed employing immunohistochemistry of tumor tissues and ex vivo analysis of murine blood serum derived from locally irradiated A549-derived tumor xenografts. Results LOX was secreted in a dose dependent way from several tumor cell lines in response to irradiation. IR did not increase LOX-transcription but induced LOX-secretion. LOX-secretion could not be prevented by the microtubule stabilizing agent patupilone. In contrast, hypoxia induced LOX-transcription, and interestingly, hypoxia-dependent LOX-secretion could be counteracted by patupilone. Conditioned media from irradiated tumor cells promoted invasiveness of naïve tumor cells, while conditioned media from irradiated, LOX- siRNA-silenced cells did not stimulate their invasive capacity. Locally applied irradiation to tumor xenografts also increased LOX-secretion in vivo and resulted in enhanced LOX-levels in the murine blood serum. Conclusions These results indicate a differential regulation of LOX-expression and secretion in response to IR and hypoxia, and suggest that LOX may contribute towards an IR-induced migratory phenotype in sublethally-irradiated tumor cells and tumor progression. PMID:25052686

2014-01-01

262

Radiation-Induced Lymphocyte Apoptosis to Predict Radiation Therapy Late Toxicity in Prostate Cancer Patients  

SciTech Connect

Purpose: To examine a potential correlation between the in vitro apoptotic response of lymphocytes to radiation and the risk of developing late gastrointestinal (GI)/genitourinary (GU) toxicity from radiotherapy for prostate cancer. Methods and Materials: Prostate cancer patients formerly enrolled in a randomized study were tested for radiosensitivity by using a radiation-induced lymphocyte apoptosis assay. Apoptosis was measured using flow cytometry-based Annexin-FITC/7AAD and DiOC{sub 6}/7AAD assays in subpopulations of lymphocytes (total lymphocytes, CD4+, CD8+ and CD4-/CD8-) after exposure to an in vitro dose of 0, 2, 4, or 8 Gy. Results: Patients with late toxicity after radiotherapy showed lower lymphocyte apoptotic responses to 8 Gy than patients who had not developed late toxicity (p = 0.01). All patients with late toxicity had apoptosis levels that were at or below the group mean. The negative predictive value in both apoptosis assays ranged from 95% to 100%, with sensitivity values of 83% to 100%. Apoptosis at lower dose points and in lymphocyte subpopulations had a weaker correlation with the occurrence of late toxicity. Conclusions: Lymphocyte apoptosis after 8 Gy of radiation has the potential to predict which patients will be spared late toxicity after radiation therapy. Further research should be performed to identify the specific subset of lymphocytes that correlates with late toxicity, followed by a corresponding prospective study.

Schnarr, Kara [Department of Medicine, St. George's University, Grenada, WI (Grenada); Boreham, Douglas [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON (Canada); Sathya, Jinka [Department of Radiation Oncology, University of Manitoba, Winnipeg, MB (Canada); Julian, Jim [Department of Oncology, McMaster University, Hamilton, Ontario (Canada); Dayes, Ian S. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON (Canada); Department of Oncology, McMaster University, Hamilton, Ontario (Canada)], E-mail: Ian.Dayes@jcc.hhsc.ca

2009-08-01

263

Fetal Radiation Exposure Induces Testicular Cancer in Genetically Susceptible Mice  

PubMed Central

The prevalence of testicular germ cell tumors (TGCT), a common solid tissue malignancy in young men, has been annually increasing at an alarming rate of 3%. Since the majority of testicular cancers are derived from germ cells at the stage of transformation of primordial germ cell (PGC) into gonocytes, the increase has been attributed to maternal/fetal exposures to environmental factors. We examined the effects of an estrogen (diethylstilbestrol, DES), an antiandrogen (flutamide), or radiation on the incidence of testicular germ cell tumors in genetically predisposed 129.MOLF-L1 (L1) congenic mice by exposing them to these agents on days 10.5 and 11.5 of pregnancy. Neither flutamide nor DES produced noticeable increases in testis cancer incidence at 4 weeks of age. In contrast, two doses of 0.8-Gy radiation increased the incidence of TGCT from 45% to 100% in the offspring. The percentage of mice with bilateral tumors, weights of testes with TGCT, and the percentage of tumors that were clearly teratomas were higher in the irradiated mice than in controls, indicating that irradiation induced more aggressive tumors and/or more foci of initiation sites in each testis. This radiation dose did not disrupt spermatogenesis, which was qualitatively normal in tumor-free testes although they were reduced in size. This is the first proof of induction of testicular cancer by an environmental agent and suggests that the male fetus of women exposed to radiation at about 5–6 weeks of pregnancy might have an increased risk of developing testicular cancer. Furthermore, it provides a novel tool for studying the molecular and cellular events of testicular cancer pathogenesis. PMID:22348147

Shetty, Gunapala; Comish, Paul B.; Weng, Connie C. Y.; Matin, Angabin; Meistrich, Marvin L.

2012-01-01

264

Dosimetric Analysis of Radiation-induced Gastric Bleeding  

SciTech Connect

Purpose: Radiation-induced gastric bleeding has been poorly understood. In this study, we described dosimetric predictors for gastric bleeding after fractionated radiation therapy. Methods and Materials: The records of 139 sequential patients treated with 3-dimensional conformal radiation therapy (3D-CRT) for intrahepatic malignancies were reviewed. Median follow-up was 7.4 months. The parameters of a Lyman normal tissue complication probability (NTCP) model for the occurrence of {>=}grade 3 gastric bleed, adjusted for cirrhosis, were fitted to the data. The principle of maximum likelihood was used to estimate parameters for NTCP models. Results: Sixteen of 116 evaluable patients (14%) developed gastric bleeds at a median time of 4.0 months (mean, 6.5 months; range, 2.1-28.3 months) following completion of RT. The median and mean maximum doses to the stomach were 61 and 63 Gy (range, 46-86 Gy), respectively, after biocorrection of each part of the 3D dose distributions to equivalent 2-Gy daily fractions. The Lyman NTCP model with parameters adjusted for cirrhosis predicted gastric bleed. Best-fit Lyman NTCP model parameters were n=0.10 and m=0.21 and with TD{sub 50} (normal) = 56 Gy and TD{sub 50} (cirrhosis) = 22 Gy. The low n value is consistent with the importance of maximum dose; a lower TD{sub 50} value for the cirrhosis patients points out their greater sensitivity. Conclusions: This study demonstrates that the Lyman NTCP model has utility for predicting gastric bleeding and that the presence of cirrhosis greatly increases this risk. These findings should facilitate the design of future clinical trials involving high-dose upper abdominal radiation.

Feng, Mary, E-mail: maryfeng@umich.edu [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States)] [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States); Normolle, Daniel [Department of Biostatistics, University of Pittsburgh, Pittsburgh, Pennsylvania (United States)] [Department of Biostatistics, University of Pittsburgh, Pittsburgh, Pennsylvania (United States); Pan, Charlie C. [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States)] [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States); Dawson, Laura A. [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario (Canada)] [Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, Ontario (Canada); Amarnath, Sudha [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States)] [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States); Ensminger, William D. [Department of Internal Medicine, Division of Hematology Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States)] [Department of Internal Medicine, Division of Hematology Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States); Lawrence, Theodore S.; Ten Haken, Randall K. [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States)] [Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, Michigan (United States)

2012-09-01

265

In situ mass spectrometry imaging and ex vivo characterization of renal crystalline deposits induced in multiple preclinical drug toxicology studies.  

PubMed

Drug toxicity observed in animal studies during drug development accounts for the discontinuation of many drug candidates, with the kidney being a major site of tissue damage. Extensive investigations are often required to reveal the mechanisms underlying such toxicological events and in the case of crystalline deposits the chemical composition can be problematic to determine. In the present study, we have used mass spectrometry imaging combined with a set of advanced analytical techniques to characterize such crystalline deposits in situ. Two potential microsomal prostaglandin E synthase 1 inhibitors, with similar chemical structure, were administered to rats over a seven day period. This resulted in kidney damage with marked tubular degeneration/regeneration and crystal deposits within the tissue that was detected by histopathology. Results from direct tissue section analysis by matrix-assisted laser desorption ionization mass spectrometry imaging were combined with data obtained following manual crystal dissection analyzed by liquid chromatography mass spectrometry and nuclear magnetic resonance spectroscopy. The chemical composition of the crystal deposits was successfully identified as a common metabolite, bisulphonamide, of the two drug candidates. In addition, an un-targeted analysis revealed molecular changes in the kidney that were specifically associated with the area of the tissue defined as pathologically damaged. In the presented study, we show the usefulness of combining mass spectrometry imaging with an array of powerful analytical tools to solve complex toxicological problems occurring during drug development. PMID:23110069

Nilsson, Anna; Forngren, Benita; Bjurström, Sivert; Goodwin, Richard J A; Basmaci, Elisa; Gustafsson, Ingela; Annas, Anita; Hellgren, Dennis; Svanhagen, Alexander; Andrén, Per E; Lindberg, Johan

2012-01-01

266

Motion-induced radiation from electrons moving in Maxwell's fish-eye  

PubMed Central

In ?erenkov radiation and transition radiation, evanescent wave from motion of charged particles transfers into radiation coherently. However, such dissipative motion-induced radiations require particles to move faster than light in medium or to encounter velocity transition to pump energy. Inspired by a method to detect cloak by observing radiation of a fast-moving electron bunch going through it by Zhang et al., we study the generation of electron-induced radiation from electrons' interaction with Maxwell's fish-eye sphere. Our calculation shows that the radiation is due to a combination of ?erenkov radiation and transition radiation, which may pave the way to investigate new schemes of transferring evanescent wave to radiation. PMID:24166002

Liu, Yangjie; Ang, L. K.

2013-01-01

267

Motion-induced radiation from electrons moving in Maxwell's fish-eye  

E-print Network

In \\u{C}erenkov radiation and transition radiation, evanescent wave from motion of charged particles transfers into radiation coherently. However, such dissipative motion-induced radiations require particles to move faster than light in medium or to encounter velocity transition to pump energy. Inspired by a method to detect cloak by observing radiation of a fast-moving electron bunch going through it by Zhang {\\itshape et al.}, we study the generation of electron-induced radiation from electrons' interaction with Maxwell's fish-eye sphere. Our calculation shows that the radiation is due to a combination of \\u{C}erenkov radiation and transition radiation, which may pave the way to investigate new schemes of transferring evanescent wave to radiation.

Liu, Yangjie

2013-01-01

268

Laser-Induced Forward Transfer-printing of pre-machined crystalline magneto-optic garnet discs  

E-print Network

the direct interaction between the laser radiation and the donor. This sacrificial layer, which is often pulse, and provides the explosive push required to propel the donor towards the receiver. However

Sóbester, András

269

Crystalline phase transition information induced by high temperature susceptibility transformations in bulk PMP-YBCO superconductor growth in-situ  

NASA Astrophysics Data System (ADS)

The dynamic susceptibility transformations of bulk HTSC PMP-YBCO growth have been investigated from 200 °C up to 1060 °C by the Faraday Balance in-situ. It revealed that the crystalline phase transitions of bulk PMP-YBCO growth in process. A new discovery of Y123 phase pre-formed then melted in heating stage has been found. It also discovered that Y123 crystal solidification started at 1004 °C in cooling stage. Before Y123 solidification the liquid phase CuO change to Cu2O reciprocally as well as the copper ion valence changed between divalent Cu2+ and trivalent Cu1+ each other. It was essential to keep quantities of CuO phase instead of the Cu2O for Y123 crystal solidification.

Zhang, C. P.; Chaud, X.; Beaugnon, E.; Zhou, L.

2015-01-01

270

Superconductivity induced by In substitution into the topological crystalline insulator Pb0.5Sn0.5Te  

NASA Astrophysics Data System (ADS)

Indium substitution turns the topological crystalline insulator (TCI) Pb0.5Sn0.5Te into a possible topological superconductor. To investigate the effect of the indium concentration on the crystal structure and superconducting properties of (Pb0.5Sn0.5)1-xInxTe, we have grown high-quality single crystals using a modified floating-zone method and have performed systematic studies for indium content in the range 0?x?0.35. We find that the single crystals retain the rocksalt structure up to the solubility limit of indium (x ˜0.30). Experimental dependencies of the superconducting transition temperature (Tc) and the upper critical magnetic field (Hc2) on the indium content x have been measured. The maximum Tc is determined to be 4.7 K at x =0.30, with ?0Hc2(T =0)?5 T.

Zhong, R. D.; Schneeloch, J. A.; Liu, T. S.; Camino, F. E.; Tranquada, J. M.; Gu, G. D.

2014-07-01

271

Radiation-induced effects and the immune system in cancer  

PubMed Central

Chemotherapy and radiation therapy (RT) are standard therapeutic modalities for patients with cancers, and could induce various tumor cell death modalities, releasing tumor-derived antigens as well as danger signals that could either be captured for triggering anti-tumor immune response. Historic studies examining tissue and cellular responses to RT have predominantly focused on damage caused to proliferating malignant cells leading to their death. However, there is increasing evidence that RT also leads to significant alterations in the tumor microenvironment, particularly with respect to effects on immune cells and infiltrating tumors. This review will focus on immunologic consequences of RT and discuss the therapeutic reprogramming of immune responses in tumors and how it regulates efficacy and durability to RT. PMID:23251903

Kaur, Punit; Asea, Alexzander

2012-01-01

272

Radiation-induced polymerization for the immobilization of penicillin acylase  

SciTech Connect

The immobilization of Escherichia coli penicillin acylase was investigated by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperature. A leak-proof composite that does not swell in water was obtained by adding the cross-linking agent trimethylolpropane trimethacrylate to the monomer-aqueous enzyme mixture. Penicillin acylase, which was immobilized with greater than 70% yield, possessed a higher Km value toward the substrate 6-nitro-3-phenylacetamidobenzoic acid than the free enzyme form (Km = 1.7 X 10(-5) and 1 X 10(-5) M, respectively). The structural stability of immobilized penicillin acylase, as assessed by heat, guanidinium chloride, and pH denaturation profiles, was very similar to that of the free-enzyme form, thus suggesting that penicillin acylase was entrapped in its native state into aqueous free spaces of the polymer matrix.

Boccu, E.; Carenza, M.; Lora, S.; Palma, G.; Veronese, F.M.

1987-06-01

273

Ventricular Tachycardia Associated with Radiation-Induced Cardiac Sarcoma  

PubMed Central

Cardiac tumors can lead to distinct electrocardiographic changes and ventricular arrhythmias. Benign and malignant cardiac tumors have been associated with ventricular tachycardia. When possible, benign tumors should be resected when ventricular arrhythmias are intractable. Chemotherapy can shrink malignant tumors and eliminate arrhythmias. We report the case of a 52-year-old woman with breast sarcoma whom we diagnosed with myocardial metastasis after she presented with palpitations. The initial electrocardiogram revealed sinus rhythm with new right bundle branch block and ST-segment elevation in the anterior precordial leads. During telemetry, hemodynamically stable, sustained ventricular tachycardia with right ventricular localization was detected. Images showed a myocardial mass in the right ventricular free wall. Amiodarone suppressed the arrhythmia. To our knowledge, this is the first report of ventricular tachycardia associated with radiation-induced undifferentiated sarcoma. We discuss the distinct electrocardiographic changes and ventricular arrhythmias that can be associated with cardiac tumors, and we review the relevant medical literature. PMID:25593527

Beaty, Elijah H.; Ballany, Wassim; Trohman, Richard G.

2014-01-01

274

Radiation induces turbulence in particle-laden fluids  

SciTech Connect

When a transparent fluid laden with solid particles is subject to radiative heating, non-uniformities in particle distribution result in local fluid temperature fluctuations. Under the influence of gravity, buoyancy induces vortical fluid motion which can lead to strong preferential concentration, enhancing the local heating and more non-uniformities in particle distribution. By employing direct numerical simulations this study shows that the described feedback loop can create and sustain turbulence. The velocity and length scale of the resulting turbulence is not known a priori, and is set by balance between viscous forces and buoyancy effects. When the particle response time is comparable to a viscous time scale, introduced in our analysis, the system exhibits intense fluctuations of turbulent kinetic energy and strong preferential concentration of particles.

Zamansky, Rémi [Centre for Turbulence Research, Stanford University, Stanford, California 94305-3035 (United States); Coletti, Filippo [Mechanical Engineering, Stanford University, California 94305-3035 (United States); Massot, Marc [Centre for Turbulence Research, Stanford University, Stanford, California 94305-3035 (United States); Ecole Centrale Paris, Laboratoire EM2C - UPR CNRS 288 et Fédération de Mathématiques - FR CNRS 3487, Grande Voie des Vignes, 92295 Chatenay-Malabry Cedex (France); Mani, Ali [Centre for Turbulence Research, Stanford University, Stanford, California 94305-3035 (United States); Mechanical Engineering, Stanford University, California 94305-3035 (United States)

2014-07-15

275

Characterization of gamma radiation inducible thioredoxin h from Spirogyra varians.  

PubMed

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

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

2013-08-15

276

Measurements of prompt radiation induced conductivity of alumina and sapphire.  

SciTech Connect

We performed measurements of the prompt radiation induced conductivity in thin samples of Alumina and Sapphire at the Little Mountain Medusa LINAC facility in Ogden, UT. Five mil thick samples were irradiated with pulses of 20 MeV electrons, yielding dose rates of 1E7 to 1E9 rad/s. We applied variable potentials up to 1 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 1E10 and 1E9 mho/m/(rad/s), depending on the dose rate and the pulse width for Alumina and 1E7 to 6E7 mho/m/(rad/s) for Sapphire.

Hartman, E. Frederick; Zarick, Thomas Andrew; Sheridan, Timothy J.; Preston, Eric F.

2011-04-01

277

Hematopoietic Stem Cell Injury Induced by Ionizing Radiation  

PubMed Central

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

Shao, Lijian; Luo, Yi

2014-01-01

278

Radiation-induced leukemia: Comparative studies in mouse and man  

SciTech Connect

We now have a clear understanding of the mechanism by which radiation-induced (T-cell) leukemia occurs. In irradiated mice (radiation-induced thymic leukemia) and in man (acute lymphoblastic T-cell leukemia, T-ALL) the mechanism of leukemogenesis is surprisingly similar. Expressed in the most elementary terms, T-cell leukemia occurs when T-cell differentiation is inhibited by a mutation, and pre-T cells attempt but fail to differentiate in the thymus. Instead of leaving the thymus for the periphery as functional T-cells they continue to proliferate in the thymus. The proliferating pre- (pro-) T-cells constitute the (early) acute T-cell leukemia (A-TCL). This model for the mechanism of T-cell leukemogenesis accounts for all the properties of both murine and human A-TCL. Important support for the model has recently come from work by Ilan Kirsch and others, who have shown that mutations/deletions in the genes SCL (TAL), SIL, and LCK constitute primary events in the development of T-ALL, by inhibiting differentiation of thymic pre- (pro-) T-cells. This mechanism of T-cell leukemogenesis brings several specific questions into focus: How do early A-TCL cells progress to become potently tumorigenic and poorly treatable Is it feasible to genetically suppress early and/or progressed A-TCL cells What is the mechanism by which the differentiation-inhibited (leukemic) pre-T cells proliferate During the first grant year we have worked on aspects of all three questions.

Haas, M.

1991-01-01

279

Bystander effects in radiation-induced genomic instability  

NASA Technical Reports Server (NTRS)

Exposure of GM10115 hamster-human hybrid cells to X-rays can result in the induction of chromosomal instability in the progeny of surviving cells. This instability manifests as the dynamic production of novel sub-populations of cells with unique cytogenetic rearrangements involving the "marker" human chromosome. We have used the comet assay to investigate whether there was an elevated level of endogenous DNA breaks in chromosomally unstable clones that could provide a source for the chromosomal rearrangements and thus account for the persistent instability observed. Our results indicate no significant difference in comet tail measurement between non-irradiated and radiation-induced chromosomally unstable clones. Using two-color fluorescence in situ hybridization we also investigated whether recombinational events involving the interstitial telomere repeat-like sequences in GM10115 cells were involved at frequencies higher than random processes would otherwise predict. Nine of 11 clones demonstrated a significantly higher than expected involvement of these interstitial telomere repeat-like sequences at the recombination junction between the human and hamster chromosomes. Since elevated levels of endogenous breaks were not detected in unstable clones we propose that epigenetic or bystander effects (BSEs) lead to the activation of recombinational pathways that perpetuate the unstable phenotype. Specifically, we expand upon the hypothesis that radiation induces conditions and/or factors that stimulate the production of reactive oxygen species (ROS). These reactive intermediates then contribute to a chronic pro-oxidant environment that cycles over multiple generations, promoting chromosomal recombination and other phenotypes associated with genomic instability.

Morgan, William F.; Hartmann, Andreas; Limoli, Charles L.; Nagar, Shruti; Ponnaiya, Brian

2002-01-01

280

Methylglyoxal-bis(guanylhydrazone), a polyamine analogue, sensitized ?-radiation-induced cell death in HL-60 leukemia cells Sensitizing effect of MGBG on ?-radiation-induced cell death.  

PubMed

Methylglyoxal-bis(guanylhydrazone) (MGBG), a polyamine analogue, has been known to inhibit the biosynthesis of polyamines, which are important in cell proliferation. We showed that MGBG treatment significantly affected ?-radiation-induced cell cycle transition (G(1)/G(0)?S?G(2)/M) and thus ?-radiation-induced cell death. As determined by micronuclei and comet assay, we showed that it sensitized the cytotoxic effect induced by ?-radiation. One of the reasons is that polyamine depletion by MGBG treatment did not effectively protect against the chemical (OH) or physical damage to DNA caused by ?-radiation. Through in vitro experiment, we confirmed that DNA strand breaks induced by ?-radiation was prevented more effectively in the presence of polyamines (spermine and spermidine) than in the absence of polyamines. MGBG also blocks the cell cycle transition caused by ?-radiation (G(2) arrest), which helps protect cells by allowing time for DNA repair before entry into mitosis or apoptosis, via the down regulation of cyclin D1, which mediates the transition from G(1) to S phase of cell cycle, and ataxia telangiectasia mutated, which is involved in the DNA sensing, repair and cell cycle check point. Therefore, the abrogation of G(2) arrest sensitizes cells to the effect of ?-radiation. As a result, ?-radiation-induced cell death increased by about 2.5-3.0-fold in cells treated with MGBG. However, exogenous spermidine supplement partially relieved this ?-radiation-induced cytotoxicity and cell death. These findings suggest a potentially therapeutic strategy for increasing the cytotoxic efficacy of ?-radiation. PMID:21783704

Kim, Jin Sik; Lee, Jin; Chung, Hai Won; Choi, Han; Paik, Sang Gi; Kim, In Gyu

2006-09-01

281

Radiation-induced chromosomal instability in human mammary epithelial cells  

NASA Technical Reports Server (NTRS)

Karyotypes of human cells surviving X- and alpha-irradiation have been studied. Human mammary epithelial cells of the immortal, non-tumorigenic cell line H184B5 F5-1 M/10 were irradiated and surviving clones isolated and expanded in culture. Cytogenetic analysis was performed using dedicated software with an image analyzer. We have found that both high- and low-LET radiation induced chromosomal instability in long-term cultures, but with different characteristics. Complex chromosomal rearrangements were observed after X-rays, while chromosome loss predominated after alpha-particles. Deletions were observed in both cases. In clones derived from cells exposed to alpha-particles, some cells showed extensive chromosome breaking and double minutes. Genomic instability was correlated to delayed reproductive death and neoplastic transformation. These results indicate that chromosomal instability is a radiation-quality-dependent effect which could determine late genetic effects, and should therefore be carefully considered in the evaluation of risk for space missions.

Durante, M.; Grossi, G. F.; Yang, T. C.

1996-01-01

282

Radiation-induced sarcomas of the head and neck.  

PubMed

With improved outcomes associated with radiotherapy, radiation-induced sarcomas (RIS) are increasingly seen in long-term survivors of head and neck cancers, with an estimated risk of up to 0.3%. They exhibit no subsite predilection within the head and neck and can arise in any irradiated tissue of mesenchymal origin. Common histologic subtypes of RIS parallel their de novo counterparts and include osteosarcoma, chondrosarcoma, malignant fibrous histiocytoma/sarcoma nitricoxide synthase, and fibrosarcoma. While imaging features of RIS are not pathognomonic, large size, extensive local invasion with bony destruction, marked enhancement within a prior radiotherapy field, and an appropriate latency period are suggestive of a diagnosis of RIS. RIS development may be influenced by factors such as radiation dose, age at initial exposure, exposure to chemotherapeutic agents and genetic tendency. Precise pathogenetic mechanisms of RIS are poorly understood and both directly mutagenizing effects of radiotherapy as well as changes in microenvironments are thought to play a role. Management of RIS is challenging, entailing surgery in irradiated tissue and a limited scope for further radiotherapy and chemotherapy. RIS is associated with significantly poorer outcomes than stage-matched sarcomas that arise independent of irradiation and surgical resection with clear margins seems to offer the best chance for cure. PMID:25493233

Thiagarajan, Anuradha; Iyer, N Gopalakrishna

2014-12-10

283

Radiation induced effects on mechanical properties of nanoporous gold foams  

NASA Astrophysics Data System (ADS)

It has recently been shown that due to a high surface-to-volume ratio, nanoporous materials display radiation tolerance. The abundance of surfaces, which are perfect sinks for defects, and the relation between ligament size, defect diffusion, and time combine to define a window of radiation resistance [Fu et al., Appl. Phys. Lett. 101, 191607 (2012)]. Outside this window, the dominant defect created by irradiation in Au nanofoams are stacking fault tetrahedra (SFT). Molecular dynamics computer simulations of nanopillars, taken as the elemental constituent of foams, predict that SFTs act as dislocation sources inducing softening, in contrast to the usual behavior in bulk materials, where defects are obstacles to dislocation motion, producing hardening. In this work we test that prediction and answer the question whether irradiation actually hardens or softens a nanofam. Ne ion irradiations of gold nanofoams were performed at room temperature for a total dose up to 4 dpa, and their mechanical behavior was measured by nanoindentation. We find that hardness increases after irradiation, a result that we analyze in terms of the role of SFTs on the deformation mode of foams.

Caro, M.; Mook, W. M.; Fu, E. G.; Wang, Y. Q.; Sheehan, C.; Martinez, E.; Baldwin, J. K.; Caro, A.

2014-06-01

284

Radiation induced effects on mechanical properties of nanoporous gold foams  

SciTech Connect

It has recently been shown that due to a high surface-to-volume ratio, nanoporous materials display radiation tolerance. The abundance of surfaces, which are perfect sinks for defects, and the relation between ligament size, defect diffusion, and time combine to define a window of radiation resistance [Fu et al., Appl. Phys. Lett. 101, 191607 (2012)]. Outside this window, the dominant defect created by irradiation in Au nanofoams are stacking fault tetrahedra (SFT). Molecular dynamics computer simulations of nanopillars, taken as the elemental constituent of foams, predict that SFTs act as dislocation sources inducing softening, in contrast to the usual behavior in bulk materials, where defects are obstacles to dislocation motion, producing hardening. In this work we test that prediction and answer the question whether irradiation actually hardens or softens a nanofam. Ne ion irradiations of gold nanofoams were performed at room temperature for a total dose up to 4 dpa, and their mechanical behavior was measured by nanoindentation. We find that hardness increases after irradiation, a result that we analyze in terms of the role of SFTs on the deformation mode of foams.

Caro, M., E-mail: magda@lanl.gov, E-mail: efu@pku.edu.cn; Fu, E. G., E-mail: magda@lanl.gov, E-mail: efu@pku.edu.cn; Wang, Y. Q.; Martinez, E.; Caro, A. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Mook, W. M.; Sheehan, C.; Baldwin, J. K. [Center for Integrated Nanotechnology, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2014-06-09

285

Are Epigenetic Mechanisms Involved in Radiation-Induced Bystander Effects?  

PubMed Central

The “non-targeted effects” of ionizing radiation including bystander effects and genomic instability are unique in that no classic mutagenic event occurs in the cell showing the effect. In the case of bystander effects, cells which were not in the field affected by the radiation show high levels of mutations, chromosome aberrations, and membrane signaling changes leading to what is termed “horizontal transmission” of mutations and information which may be damaging while in the case of genomic instability, generations of cells derived from an irradiated progenitor appear normal but then lethal and non-lethal mutations appear in distant progeny. This is known as “vertical transmission.” In both situations high yields of non-clonal mutations leading to distant occurrence of mutation events both in space and time. This precludes a mutator phenotype or other conventional explanation and appears to indicate a generalized form of stress-induced mutagenesis which is well documented in bacteria. This review will discuss the phenomenology of what we term “non-targeted effects,” and will consider to what extent they challenge conventional ideas in genetics and epigenetics. PMID:22629281

Mothersill, Carmel; Seymour, Colin

2012-01-01

286

Heterogeneous shock-induced thermal radiation in minerals  

NASA Technical Reports Server (NTRS)

A 500-channel optical imaging intensifying and spectral digital recording system is used for recording the shock-induced radiation emitted from 406 to 821 nm from transparent minerals during the time interval that a shock wave propagates through the sample. The initial results obtained for single crystals of gypsum, calcite and halite in the 30 to 40 GPa (300 to 400 kbar) pressure range reveal grey-body emission spectra corresponding to temperatures in the 3000 to 4000 K range and emissivities ranging from 0.003 to 0.02. With gypsum and calcite, distinctive line spectra are superimposed on the thermal radiation. The observed color temperatures are greater than the Hugoniot temperature by a factor of 2 to 10; this is calculable on the basis of continuum thermodynamics and equation of state models for the shock states achieved in the three minerals. These observed high temperatures are thought to be real. It is concluded that a large number of closed spaced high temperature shear-band regions are being detected immediately behind the shock front.

Kondo, K.-I.; Ahrens, T. J.

1983-01-01

287

Radiation-induced sarcomas of the head and neck  

PubMed Central

With improved outcomes associated with radiotherapy, radiation-induced sarcomas (RIS) are increasingly seen in long-term survivors of head and neck cancers, with an estimated risk of up to 0.3%. They exhibit no subsite predilection within the head and neck and can arise in any irradiated tissue of mesenchymal origin. Common histologic subtypes of RIS parallel their de novo counterparts and include osteosarcoma, chondrosarcoma, malignant fibrous histiocytoma/sarcoma nitricoxide synthase, and fibrosarcoma. While imaging features of RIS are not pathognomonic, large size, extensive local invasion with bony destruction, marked enhancement within a prior radiotherapy field, and an appropriate latency period are suggestive of a diagnosis of RIS. RIS development may be influenced by factors such as radiation dose, age at initial exposure, exposure to chemotherapeutic agents and genetic tendency. Precise pathogenetic mechanisms of RIS are poorly understood and both directly mutagenizing effects of radiotherapy as well as changes in microenvironments are thought to play a role. Management of RIS is challenging, entailing surgery in irradiated tissue and a limited scope for further radiotherapy and chemotherapy. RIS is associated with significantly poorer outcomes than stage-matched sarcomas that arise independent of irradiation and surgical resection with clear margins seems to offer the best chance for cure. PMID:25493233

Thiagarajan, Anuradha; Iyer, N Gopalakrishna

2014-01-01

288

Interference detection in implantable defibrillators induced by therapeutic radiation therapy  

PubMed Central

Background Electromagnetic fields and ionising radiation during radiotherapy can influence the functioning of ICDs. Guidelines for radiotherapy treatment were published in 1994, but only based on experience with pacemakers. Data on the influence of radiotherapy on ICDs is limited. Objectives We determined the risk to ICDs of interference detection induced by radiotherapy. Methods In our study we irradiated 11 ICDs. The irradiation was performed with a 6 megavolt photon beam. In each individual device test, a total of 20 Gray was delivered in a fractionated fashion. During each irradiation the output stimulation rate was monitored and electrogram storage was activated. In case of interference the test was repeated with the ICD outside and the lead(s) inside and outside the irradiation field. Results With the ICD inside the irradiation field, interference detection was observed in all ICDs. This caused pacing inhibition or rapid ventricular pacing. Ventricular tachycardia (VT) or ventricular fibrillation (VF) detection occurred, which would have caused tachycardia-terminating therapy. If the ICD was placed outside the irradiation field, no interference was observed. Conclusion Interference by ionising radiation on the ICDs is demonstrated both on bradycardia and tachycardia therapy. This can have consequences for patients. Recommendations for radiotherapy are presented in this article. ImagesFigure 1Figure 5 PMID:25696559

Uiterwaal, G.J.; Springorum, B.G.F.; Scheepers, E.; de Ruiter, G.S.; Hurkmans, C.W.

2006-01-01

289

Chromatin Structure and Radiation-Induced Intrachromosome Exchange  

NASA Technical Reports Server (NTRS)

We have recently investigated the location of breaks involved in intrachromosomal type exchange events, using the multicolor banding in situ hybridization (mBAND) technique for human chromosome 3. In human epithelial cells exposed to both low- and high-LET radiations in vitro, intrachromosome exchanges were found to occur preferentially between a break in the 3p21 and one in the 3q11. Exchanges were also observed between a break in 3p21 and one in 3q26, but few exchanges were observed between breaks in 3q11 and 3q26, even though the two regions were on the same arm of the chromosome. To explore the relationships between intrachromosome exchanges and chromatin structure, we used probes that hybridize the three regions of 3p21, 3q11 and 3q26, and measured the distance between two of the three regions in interphase cells. We further analyzed fragile sites on the chromosome that have been identified in various types of cancers. Our results demonstrated that the distribution of breaks involved in radiation-induced intrachromosome aberrations depends upon both the location of fragile sites and the folding of chromatins

Mangala; Zhang, Ye; Hada, Megumi; Cucinotta, Francis A.; Wu, Honglu

2011-01-01

290

Transient and stationary flow behaviour of side chain liquid-crystalline polymers: Evidence of a shear-induced isotropic-to-nematic phase transition  

NASA Astrophysics Data System (ADS)

This letter describes the non-linear rheology of the isotropic phase of a thermotropic side chain liquid-crystal polymer (SCLCP), from which we infer a flow-induced iso- tropic-to-nematic (IN) phase transition above a critical shear stress and construct non-equilib- rium phase diagrams. In contrast to the well-studied wormlike-micellar solutions and predictions for simple liquid-crystalline systems, the critical stress does not vanish as the equilibrium transition temperature is approached from the above. We postulate that this is due to: i) the coupling between mesogens and the polymer backbone, whose equilibrium oblate nematic backbone conformation contrasts with the prolate non-equilibrium conformation; and ii) the peculiar topological constraints in SCLCP melts, which have been previously postulated as leading to long-lived clusters.

Pujolle-Robic, C.; Olmsted, P. D.; Noirez, L.

2002-08-01

291

Radiation-induced taste aversion: effects of radiation exposure level and the exposure-taste interval  

SciTech Connect

Radiation-induced taste aversion has been suggested to possibly play a role in the dietary difficulties observed in some radiotherapy patients. In rats, these aversions can still be formed even when the radiation exposure precedes the taste experience by several hours. This study was conducted to examine whether increasing the radiation exposure level could extend the range of the exposure-taste interval that would still support the formation of a taste aversion. Separate groups of rats received either a 100 or 300 R gamma-ray exposure followed 1, 3, 6, or 24 h later by a 10-min saccharin (0.1% w/v) presentation. A control group received a sham exposure followed 1 h later by a 10-min saccharin presentation. Twenty-four hours following the saccharin presentation all rats received a series of twelve 23-h two-bottle preference tests between saccharin and water. The results indicated that the duration of the exposure-taste interval plays an increasingly more important role in determining the initial extent of the aversion as the dose decreases. The course of recovery from taste aversion seems more affected by dose than by the temporal parameters of the conditioning trial.

Spector, A.C.; Smith, J.C.; Hollander, G.R.

1986-05-01

292

Attenuation of a radiation-induced conditioned taste aversion after the development of ethanol tolerance  

SciTech Connect

An attempt to reduce a radiation-induced conditioned taste aversion (CTA) was undertaken by rendering animals tolerant to ethanol. Ethanol tolerance, developed over 5 days, was sufficient to block a radiation-induced taste aversion, as well as an ethanol-induced CTA. Several intermittent doses of ethanol, which did not induce tolerance but removed the novelty of the conditioning stimulus, blocked an ethanol-induced CTA but not the radiation-induced CTA. A CTA induced by doses of radiation up to 500 rads was attenuated. These data suggest that radioprotection developing in association with ethanol tolerance is a result of a physiological response to the chronic presence of ethanol not to the ethanol itself.

Hunt, W.A.; Rabin, B.M.

1988-01-01

293

Mitochondrial ROS and radiation induced transformation in mouse embryonic fibroblasts  

PubMed Central

Manganese superoxide dismutase (SOD2) is a nuclear encoded and mitochondria localized antioxidant enzyme that converts mitochondria derived superoxide to hydrogen peroxide. This study investigates the hypothesis that mitochondria derived reactive oxygen species (ROS) regulate ionizing radiation (IR) induced transformation in normal cells. Mouse embryonic fibroblasts (MEFs) with wild type SOD2 (+/+), heterozygous SOD2 (+/?), and homozygous SOD2 (?/?) genotypes were irradiated with equitoxic doses of IR, and assayed for transformation frequency, cellular redox environment, DNA damage, and cell cycle checkpoint activation. Transformation frequency increased (~ 5-fold) in SOD2 (?/?) compared to SOD2 (+/+) MEFs. Cellular redox environment (GSH, GSSG, DHE, and DCFH-oxidation) did not show any significant change within 24h post-IR. However, a significant increase in cellular ROS levels was observed at 72h post-IR in SOD2 (?/?) compared to SOD2 (+/+) MEFs, which was consistent with an increase in GSSG in SOD2 (?/?) MEFs. Late ROS accumulation was associated with an increase in micronuclei frequency in SOD2 (?/?) MEFs. Exit from G2 was accelerated in irradiated SOD2 (+/?) and SOD2 (?/?) compared to SOD2 (+/+) MEFs. These results support the hypothesis that SOD2 activity and mitochondria generated ROS regulate IR induced transformation in mouse embryonic fibroblasts. PMID:19738419

Du, Changbin; Gao, Zhen; Venkatesha, Venkatasubbaiah A.; Kalen, Amanda L.; Chaudhuri, Leena; Spitz, Douglas R.; Cullen, Joseph J.; Oberley, Larry W.; Goswami, Prabhat C.

2009-01-01

294

Universal damage factor for radiation-induced dark current in silicon devices  

Microsoft Academic Search

A new damage factor formulation is presented for describing radiation-induced dark current in silicon devices. This damage factor, K dark, is the number of carriers thermally generated per unit volume per unit time in a depletion region per unit nonionizing dose deposited in that volume. Kdark appears to account successfully for the mean radiation-induced dark current for any silicon device

J. R. Srour; D. H. Lo

2000-01-01

295

Ionizing radiation induced leakage current on ultra-thin gate oxides  

Microsoft Academic Search

MOS capacitors with a 4.4 nm thick gate oxide have been exposed to ? radiation from a Co60 source. As a result, we have measured a stable leakage current at fields lower than those required for Fowler-Nordheim tunneling. This Radiation Induced Leakage Current (RILC) is similar to the usual Stress Induced Leakage Currents (SILC) observed after electrical stresses of MOS

A. Scarpa; A. Paccagnella; F. Montera; G. Ghibaudo; G. Pananakakis; G. Ghidini; P. G. Fuochi

1997-01-01

296

Time course of radiation-induced apoptosis in the adult rat spinal cord  

Microsoft Academic Search

Radiation-induced apoptosis has been reported in thymic, lymphoid, haematopoietic cells and intestinal epithelium but is infrequently documented in other adult mammalian cell types. In this study, we examined the time course of radiation-induced apoptosis in the adult cervical rat spinal cord following a single dose of 8 or 22 Gy. Apoptosis was assessed by morphological criteria under light and electron

Y. Q. Li; Y. P. Guo; V. Jay; P. A. Stewart; C. S. Wong

1996-01-01

297

Radiation from large space structures in low earth orbit with induced alternating currents  

Microsoft Academic Search

Large conducting space structures in low Earth orbit will have a nonnegligible motionally induced potential across their structures. The induced current flow through the body and the ionosphere causes the radiation of Alfvén and lower hybrid waves. This current flow is taken to be ac, and the radiated power is studied as a function of the ac frequency. The current

D. E. Hastings; A. Barnett; S. Olbert

1988-01-01

298

Simulating and Detecting Radiation-Induced Errors for Onboard Machine Learning  

E-print Network

Simulating and Detecting Radiation-Induced Errors for Onboard Machine Learning Robert Granat, Kiri-based fault tolerance (ABFT) methods into onboard data analysis algorithms to detect radiation-induced errors" machine learning algorithms. I. INTRODUCTION AND OBJECTIVES Onboard data analysis is a powerful capability

Wagstaff, Kiri L.

299

Effects of exogenous carbon monoxide on radiation-induced bystander effect in zebrafish embryos in vivo  

E-print Network

Effects of exogenous carbon monoxide on radiation-induced bystander effect in zebrafish embryos Zebrafish embryos CO CORM-3 a b s t r a c t In the present work, the influence of a low concentration) on the radiation induced bystander effect (RIBE) in vivo between embryos of the zebrafish was studied. RIBE

Yu, K.N.

300

DETECTION OF LOW DOSE RADIATION INDUCED DNA DAMAGE USING TEMPERATURE DIFFERENTIAL FLUORESCENCE ASSAY  

EPA Science Inventory

A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposur...

301

DETECTION OF LOW DOSE RADIATION INDUCED DNA DAMAGE USING TEMPERATURE DIFFERENNTIAL FLUORESENCE ASSAY  

EPA Science Inventory

A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposures...

302

FEM numerical analysis of excimer laser induced modification in alternating multi-layers of amorphous and nano-crystalline silicon films  

NASA Astrophysics Data System (ADS)

UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193 nm radiation with 25 ns pulse length and energy densities ranging from 50 mJ/cm2 to 400 mJ/cm2 have been calculated. Numerical results allowed us to estimate the dehydrogenation process of the different layers and the diffusion of phosphorous (P) in Si layers as well as their structural modifications as a function of the applied laser energy density. Numerical results are compared with exhaustive characterization of the experimental results.

Conde, J. C.; Martín, E.; Stefanov, S.; Alpuim, P.; Chiussi, S.

2012-09-01

303

Response of mouse tumor to interferon inducer and radiation.  

PubMed

The antitumor effect of interferon inducer poly(ICLC), given prior to the radiation treatment of Lewis lung carcinoma in C57Bl mice was studied. To induce the tumors, the mice were injected subcutaneously into the hind leg with 3 X 10(4) or 3 X 10(5) tumor cells. The combination treatment consisted of poly(ICLC) given at 1.25 mg/kg 6 hours before 400 cGy of 60Co gamma rays. All treatments were given three times over 1.5 weeks. The local response, as measured by the delay in the tumor growth, was significantly higher in the combination treatment group than in poly(ICLC) or local irradiation groups. Following the termination of treatment, tumor regrowth was observed. The survival of poly(ICLC) treated mice was influenced by the number of transplanted tumor cells. Thus, untreated mice which received 3 X 10(4) or 3 X 10(5) (2 or 20 TD50) of tumor cells had similar mean survival time of 25.4 +/- 1.9 and 22 +/- 84 days, respectively (p greater than 0.05). The mice, treated by a combination of poly(ICLC) and local irradiation survived 48.2 +/- 2.1 days and 30.7 +/- 1.2 days (p less than .01), with higher survival in 2 TD50 tumor cell groups. Thus, data obtained in this study in mice showed that administration of an interferon inducer poly(ICLC) prior to local irradiation can improve tumor response and survival. PMID:4030439

Lvovsky, E A; Mossman, K L; Levy, H B; Dritschilo, A

1985-09-01

304

Radiation-induced osteosarcomas in the pediatric population  

SciTech Connect

Purpose: Radiation-induced osteosarcomas (R-OS) have historically been high-grade, locally invasive tumors with a poor prognosis. The purpose of this study was to perform a comprehensive literature review and analysis of reported cases dealing with R-OS in the pediatric population to identify the characteristics, prognostic factors, optimal treatment modalities, and overall survival of these patients. Methods and Materials: A MEDLINE/PubMed search of articles written in the English language dealing with OSs occurring after radiotherapy (RT) in the pediatric population yielded 30 studies from 1981 to 2004. Eligibility criteria included patients <21 years of age at the diagnosis of the primary cancer, cases satisfying the modified Cahan criteria, and information on treatment outcome. Factors analyzed included the type of primary cancer treated with RT, the radiation dose and beam energy, the latency period between RT and the development of R-OS, and the treatment, follow-up, and final outcome of R-OS. Results: The series included 109 patients with a median age at the diagnosis of primary cancer of 6 years (range, 0.08-21 years). The most common tumors treated with RT were Ewing's sarcoma (23.9%), rhabdomyosarcoma (17.4%), retinoblastoma (12.8%), Hodgkin's disease (9.2%), brain tumor (8.3%), and Wilms' tumor (6.4%). The median radiation dose was 47 Gy (range, 15-145 Gy). The median latency period from RT to the development of R-OS was 100 months (range, 36-636 months). The median follow-up after diagnosis of R-OS was 18 months (1-172 months). The 3- and 5-year cause-specific survival rate was 43.6% and 42.2%, respectively, and the 3- and 5-year overall survival rate was 41.7% and 40.2%, respectively. Variables, including age at RT, primary site, type of tumor treated with RT, total radiation dose, and latency period did not have a significant effect on survival. The 5-year cause-specific and overall survival rate for patients who received treatment for R-OS involving chemotherapy alone, surgery alone, and surgery plus chemotherapy was 17.3% and 17.3%, 56.6% and 50.3%, and 71.0% and 68.3%, respectively (p < 0.0001, log-rank test). Conclusion: The type of treatment for R-OS was the most significant factor for cause-specific and overall survival. Patients who develop R-OS should be aggressively treated, because the outcome is not as dismal as once thought.

Koshy, Matthew [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States); Paulino, Arnold C. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States)]. E-mail: apaulino@tmh.tmc.edu; Mai, Wei Y. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States); Teh, Bin S. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States)

2005-11-15

305

Characterization of a Novel Epigenetic Effect of Ionizing Radiation: The Death-Inducing Effect1  

Microsoft Academic Search

The detrimental effects associated with exposure to ionizing radiation have long been thought to result from the direct targeting of the nucleus leading to DNA damage; however, the emergence of concepts such as radiation-induced genomic instability and bystander effects have chal- lenged this dogma. After cellular exposure to ionizing radiation, we have isolated a number of clones of Chinese hamster-human

Shruti Nagar; Leslie E. Smith; William F. Morgan

306

Pressure-sensitive blackbody point radiation induced by infrared diode laser irradiation  

E-print Network

Pressure-sensitive blackbody point radiation induced by infrared diode laser irradiation Feng Qin,1 Ultrabroadband radiation from Yb2O3 at ambient and low air pressures was investigated under the excitation to environmental air pressure in the way that the integrated radiation intensity decreases linearly with increasing

Cao, Wenwu

307

Effects of subdiaphragmatic vagotomy on the acquisition of a radiation-induced conditioned taste aversion  

SciTech Connect

The effect of subdiaphragmatic vagotomy on the acquisition of a radiation-induced taste aversion was examined to assess the importance of the vagus nerve in transmitting information on the peripheral toxicity of radiation to the brain. Vagotomy had no effect on taste aversion learning, consistent with reports using other toxins. The data support the involvement of a blood-borne factor in the acquisition of taste aversion induced by ionizing radiation.

Hunt, W.A.; Rabin, B.M.; Lee, J.

1987-01-01

308

Time dependent annealing of radiation - induced leakage currents in MOS devices  

Microsoft Academic Search

Results are presented showing the radiation response of several unhardened commercial 1.25-μm bulk CMOS processes using LOCOS isolation technology. In all cases studied radiation-induced failure is caused by effects in the field oxide, and the radiation-induced δV{sub T} in the channel region is usually small at the failure dose. Time dependent leakage current data for the field oxides are presented

J. M. Terrell; T. R. Olkham; A. J. Lelis; J. M. Benedetto

1989-01-01

309

Arachidonic Acid Metabolites Mediate the Radiation-Induced Increase in Glomerular Albumin Permeability  

Microsoft Academic Search

Radiation-induced renal injury is characterized by proteinuria, hypertension, and progressive decline in renal function. We have previously shown that in vivo or in vitro irradiation of glomeruli with a single dose of radiation (9.5 Gy) increases glomerular albumin permeability (Palb) within 1 hr. The current studies tested the hypothesis that this early radiation-induced increase in Palb is caused by the

MUKUT SHARMA; ELLEN T. MCCARTHY; RAM SHARMA; BRIAN L. FISH; VIRGINIA J. SAVIN; ERIC P. COHEN; JOHN E. MOULDER

310

Femtosecond laser-induced cross-periodic structures on a crystalline silicon surface under low pulse number irradiation  

NASA Astrophysics Data System (ADS)

A cross-patterned surface periodic structure in femtosecond laser processing of crystalline silicon was revealed under a relatively low shots (4 < N < 10) with the pulse energy slightly higher than the ablation threshold. The experimental results indicated that the cross-pattern was composed of mutually orthogonal periodic structures (ripples). Ripples with a direction perpendicular to laser polarization (R?) spread in the whole laser-modified region, with the periodicity around 780 nm which was close to the central wavelength of the laser. Other ripples with a direction parallel to laser polarization (R?) were found to be distributed between two of the adjacent ripples R?, with a periodicity about the sub-wavelength of the irradiated laser, 390 nm. The geometrical morphology of two mutually orthogonal ripples under static femtosecond laser irradiation could be continuously rotated as the polarization directions changed, but the periodicity remained almost unchanged. The underlying physical mechanism was revealed by numerical simulations based on the finite element method. It was found that the incubation effect with multiple shots, together with the redistributed electric field after initial ablation, plays a crucial role in the generation of the cross-patterned periodic surface structures.

Ji, Xu; Jiang, Lan; Li, Xiaowei; Han, Weina; Liu, Yang; Wang, Andong; Lu, Yongfeng

2015-01-01

311

Tunable terahertz radiation from an ultrashort-laser-pulse-induced discharge in biased air  

Microsoft Academic Search

Strong beams of coherent radiation are essential to induce nonlinear excitation phenomena in biology and material sciences. Optical-field-induced ionization by an ultrashort laser pulse produces ultrabroadband bursts of radiation with photon energies ranging from radio-wave at the microsecond timescale to x-ray at the attosecond timescale. As the laser pulse drives an ultrafast-discharge with high current it induces nonlinear spectral conversion

Fuminori Suzuki; Hiroaki Anno-Kashiwazaki; Jun Miyazawa; Shohei Ono; Takeshi Higashiguchi; Noboru Yugami; Yasuhiko Sentoku; Ryosuke Kodama; Patric Muggli

2011-01-01

312

Single-crystalline organic-inorganic layered cobalt hydroxide nanofibers: facile synthesis, characterization, and reversible water-induced structural conversion.  

PubMed

New pink organic-inorganic layered cobalt hydroxide nanofibers intercalated with benzoate ions [Co(OH)(C6H5COO)·H2O] have been synthesized by using cobalt nitrate and sodium benzoate as reactants in water with no addition of organic solvent or surfactant. The high-purity nanofibers are single-crystalline in nature and very uniform in size with a diameter of about 100 nm and variable lengths over a wide range from 200 ?m down to 2 ?m by simply adjusting reactant concentrations. The as-synthesized products are well-characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), fast Fourier transforms (FFT), X-ray diffraction (XRD), energy dispersive X-ray spectra (EDX), X-ray photoelectron spectra (XPS), elemental analysis (EA), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and UV-vis diffuse reflectance spectra (UV-vis). Our results demonstrate that the structure consists of octahedral cobalt layers and the benzoate anions, which are arranged in a bilayer due to the ?-? stacking of small aromatics. The carboxylate groups of benzoate anions are coordinated to Co(II) ions in a strong bridging mode, which is the driving force for the anisotropic growth of nanofibers. When NaOH is added during the synthesis, green irregular shaped platelets are obtained, in which the carboxylate groups of benzoate anions are coordinated to the Co(II) ions in a unidentate fashion. Interestingly, the nanofibers exhibit a reversible transformation of the coordination geometry of the Co(II) ions between octahedral and pseudotetrahedral with a concomitant color change between pink and blue, which involves the loss and reuptake of unusual weakly coordinated water molecules without destroying the structure. This work offers a facile, cost-effective, and green strategy to rationally design and synthesize functional nanomaterials for future applications in catalysis, magnetism, gas storage or separation, and sensing technology. PMID:25423999

Guo, Xiaodi; Wang, Lianying; Yue, Shuang; Wang, Dongyang; Lu, Yanluo; Song, Yufei; He, Jing

2014-12-15

313

Radiation-Induced Topological Disorder in Irradiated Network Structures  

SciTech Connect

This report summarizes results of a research program investigating the fundamental principles underlying the phenomenon of topological disordering in a radiation environment. This phenomenon is known popularly as amorphization, but is more formally described as a process of radiation-induced structural arrangement that leads in crystals to loss of long-range translational and orientational correlations and in glasses to analogous alteration of connectivity topologies. The program focus has been on a set compound ceramic solids with directed bonding exhibiting structures that can be described as networks. Such solids include SiO2, Si3N4, SiC, which are of interest to applications in fusion energy production, nuclear waste storage, and device manufacture involving ion implantation or use in radiation fields. The principal investigative tools comprise a combination of experimental diffraction-based techniques, topological modeling, and molecular-dynamics simulations that have proven a rich source of information in the preceding support period. The results from the present support period fall into three task areas. The first comprises enumeration of the rigidity constraints applying to (1) more complex ceramic structures (such as rutile, corundum, spinel and olivine structures) that exhibit multiply polytopic coordination units or multiple modes of connecting such units, (2) elemental solids (such as graphite, silicon and diamond) for which a correct choice of polytope is necessary to achieve correct representation of the constraints, and (3) compounds (such as spinel and silicon carbide) that exhibit chemical disorder on one or several sublattices. With correct identification of the topological constraints, a unique correlation is shown to exist between constraint and amorphizability which demonstrates that amorphization occurs at a critical constraint loss. The second task involves the application of molecular dynamics (MD) methods to topologically-generated models of amorphized network silicas. These methods are shown to generate fully connected topologically-disordered networks, equilibrated to achieve accurately-specified atomic coordinates that can be compared to correlation data derived from diffraction experiments. The MD equilibrations demonstrate the insensitivity of diffraction methods to substantial differences in intermediate-range topology, with the exception of the first diffraction peak which is shown to be uniquely sensitive to topological differences. The third task concerns application of MD simulations to amorphization of silicon carbide, which exhibits anomalous amorphizability. Amorphization of this compound is shown to derive from its facility for tolerating chemical disorder, and a critical homonuclear bond density threshold is established as a criterion for its amorphization.

Hobbs, Linn W.

2002-12-21

314

Preliminary results on the relationship between luminescence and crystalline structure of lithium metatitanate  

NASA Astrophysics Data System (ADS)

Lithium metatitanate is a luminescent ceramic material of promising properties for numerous applications (breeder blanket in fusion reactors, ionic conductors). In some cases, the material will be submitted to aggressive environments (radiation, chemicals, high temperatures), which could induce changes in the crystalline structure. Small variations (presence of inclusions, impurities, or surface) in the lattice of crystalline solids are known to change the light emission behaviour, i.e. intensity and wavelength position of photoluminescence. Li2TiO3 ceramic samples were sintered in the range of 1050 and 1350 °C to modify the high temperature crystalline structure, and then were characterized by means of their cathodoluminescence (CL) and thermoluminescence (TL) properties as a function of total radiation dose and time of storage.

Correcher, V.; González, M.

2014-05-01

315

ULTRASTRUCTURAL STUDIES OF RADIATION-INDUCED CHROMOSOME DAMAGE  

PubMed Central

The fine structure of radiation-induced chromosomal aberrations in Potorous tridactylis (rat kangaroo) cells was examined in situ by electron microscopy. The observations on the structure of terminal deletions (acentric fragments), anaphase bridges and "gaps," sidearm bridges, and specialized regions, such as the nucleolus organizer, are discussed in detail. Conclusions based on these observations are the following: (a) damage is physically expressed only at anaphase; (b) a gap region is composed of two subunits, each of which is about 800–1000 A in diameter and may correspond to a half-chromatid structure; (c) the ends of acentric fragments are structurally similar to normal chromosome ends, except where the break occurs in a specific region such as the secondary constriction; (d) at metaphase the fragment and the main portion of the chromosome move as a single unit to the equator, and the two units are disconnected only at the onset of anaphase; (e) sidearm bridges appear to be exchanges, involving a subchromatid unit. The interpretation of this evidence is consistent with the hypothesis that the chromosome is a multistranded structure. PMID:4895598

Humphrey, Ronald M.; Brinkley, B. R.

1969-01-01

316

Does oxygen enhance the radiation-induced inactivation of penicillinase  

SciTech Connect

The radiation-induced inactivation of penicillinase (..beta..-lactamase, EC 3.5.2.6) in dilute aqueous solutions buffered with phosphate was studied by examining enzyme radiosensitivity in the presence of various gases (He, O/sub 2/, H/sub 2/, N/sub 2/O and N/sub 2/O + O/sub 2/). The introduction of either N/sub 2/O or O/sub 2/ was found to reduce the radiodamage. On the other hand, H/sub 2/ or N/sub 2/O + O/sub 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 more than twofold higher than that of OH radicals; therefore, in 50 mM phosphate buffer, where more than half the free radicals are H atoms, the H radicals are responsible for the majority of the damage. The superoxide radicals appeared to be completely inactive and did not contribute to enzyme inactivation. Oxygen affected the radiosensitivity in two ways: (1) it protected by converting e/sub aq//sup -/ and H into harmless O/sub 2/-radicals; and (2) it increased inactivation by enhancing the damage brought about by OH radicals (OER = 2.6). In oxygenated buffer the protection effect of oxygen exceeded that of sensitization, thus giving rise to a moderate overall protection effect.

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

1980-04-01

317

Ultrasonic Measurement of Microdisplacement Induced by Acoustic Radiation Force  

NASA Astrophysics Data System (ADS)

Quantitative evaluation of human skin aging is achieved by measuring the viscoelasticity of the skin. In the present study, microdisplacement induced by acoustic radiation force (ARF) is quantitatively measured by high-frequency ultrasonography (HFUS) and the result is confirmed by laser-Doppler velocimetry (LDV). Poly(vinyl alcohol) (PVA) with 1% cellulose particles was used as the biological phantom. A concave piezoelectric zirconate titanate (PZT) transducer with a diameter and focal length of 3 cm was used as an applicator to generate ARF. Microdisplacement at each depth of PVA was measured by the phased tracking method at 100 MHz of ultrasound with a repetition rate of 2000 Hz. When 80 tone-burst pulses were applied, the displacement measured by HFUS was 9 µm and the same result was obtained by LDV. As the displacement at each depth of PVA is measurable using ARF and the HFUS system, the system could be applied to measuring the viscoelasticity of the layered structure of the human skin.

Nagaoka, Ryo; Izumi, Takuya; Komatsu, Yosuke; Kobayashi, Kazuto; Saijo, Yoshifumi

2013-07-01

318

Revisit on dynamic radiation forces induced by pulsed Gaussian beams  

NASA Astrophysics Data System (ADS)

Motivated by the recent optical trapping experiments using ultra-short pulsed lasers [Opt. Express 18, 7554 (2010); Appl. Opt. 48, G33 (2009)], in this paper we have re-investigated the trapping effects of the pulsed radiation force (PRF), which is induced by a pulsed Gaussian beam acting on a Rayleigh dielectric sphere. Based on our previous model [Opt. Express 15, 10615 (2007)], we have considered the effects arisen from both the transverse and axial PRFs, which lead to the different behaviors of both velocities and displacements of a Rayleigh particle within a pulse duration. Our analysis shows that, for the small-sized Rayleigh particles, when the pulse has the large pulse duration, it might provide the three-dimensional optical trapping; and when the pulse has the short pulse duration, it only provides the two-dimensional optical trapping with the axial movement along the pulse propagation. When the particle is in the vacuum or in the situation with the very weak Brownian motion, the particle can always be trapped stably due to the particle's cumulative momentum transferred from the pulse, and only in this case the trapping effect is independent of pulse duration. Finally, we have predicted that for the large-sized Rayleigh particles, the pulse beam can only provide the two-dimensional optical trap (optical guiding). Our results provide the important information about the trapping mechanism of pulsed tweezers.

Wang, Li-Gang; Chai, Hai-Shui

2011-07-01

319

Revisit on dynamic radiation forces induced by pulsed Gaussian beams.  

PubMed

Motivated by the recent optical trapping experiments using ultra-short pulsed lasers [Opt. Express 18, 7554 (2010); Appl. Opt. 48, G33 (2009)], in this paper we have re-investigated the trapping effects of the pulsed radiation force (PRF), which is induced by a pulsed Gaussian beam acting on a Rayleigh dielectric sphere. Based on our previous model [Opt. Express 15, 10615 (2007)], we have considered the effects arisen from both the transverse and axial PRFs, which lead to the different behaviors of both velocities and displacements of a Rayleigh particle within a pulse duration. Our analysis shows that, for the small-sized Rayleigh particles, when the pulse has the large pulse duration, it might provide the three-dimensional optical trapping; and when the pulse has the short pulse duration, it only provides the two-dimensional optical trapping with the axial movement along the pulse propagation. When the particle is in the vacuum or in the situation with the very weak Brownian motion, the particle can always be trapped stably due to the particle's cumulative momentum transferred from the pulse, and only in this case the trapping effect is independent of pulse duration. Finally, we have predicted that for the large-sized Rayleigh particles, the pulse beam can only provide the two-dimensional optical trap (optical guiding). Our results provide the important information about the trapping mechanism of pulsed tweezers. PMID:21934801

Wang, Li-Gang; Chai, Hai-Shui

2011-07-18

320

Radiation induced failures of complementary metal oxide semiconductor containing pacemakers: a potentially lethal complication  

SciTech Connect

New multi-programmable pacemakers frequently employ complementary metal oxide semiconductors (CMOS). This circuitry appears more sensitive to the effects of ionizing radiation when compared to the semiconductor circuits used in older pacemakers. A case of radiation induced runaway pacemaker in a CMOS device is described. Because of this and other recent reports of radiation therapy-induced CMOS type pacemaker failure, these pacemakers should not be irradiated. If necessary, the pacemaker can be shielded or moved to a site which can be shielded before institution of radiation therapy. This is done to prevent damage to the CMOS circuit and the life threatening arrythmias which may result from such damage.

Lewin, A.A.; Serago, C.F.; Schwade, J.G.; Abitbol, A.A.; Margolis, S.C.

1984-10-01

321

Harmonic Tracking of Acoustic Radiation Force Induced Displacements  

PubMed Central

Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse inversion techniques. The method is implemented with Acoustic Radiation Force Impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8 MHz harmonic images created using a bandpass filter approach and the fully sampled pulse inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower and higher frequency methods suggests that any improvement due to the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse inversion harmonic ARFI images. Within the lumen, the harmonic tracking methods improved the discrimination of the blood–vessel interface, making it easier to visualize plaque boundaries. Improvements in harmonic ARFI images in vivo were consistent with suppressed clutter supported by improved contrast and CNR in the matched harmonic B-mode images compared to the fundamental B-mode images. These results suggest that harmonic tracking methods can improve the clinical utility and diagnostic accuracy of ultrasound-based elasticity imaging methods. PMID:24158290

Doherty, Joshua R.; Dahl, Jeremy J.; Trahey, Gregg E.

2014-01-01

322

Radiation-induced gene expression in the nematode Caenorhabditis elegans  

NASA Technical Reports Server (NTRS)

We used the nematode C. elegans to characterize the genotoxic and cytotoxic effects of ionizing radiation in a simple animal model emphasizing the unique effects of charged particle radiation. Here we demonstrate by RT-PCR differential display and whole genome microarray hybridization experiments that gamma rays, accelerated protons and iron ions at the same physical dose lead to unique transcription profiles. 599 of 17871 genes analyzed (3.4%) showed differential expression 3 hrs after exposure to 3 Gy of radiation. 193 were up-regulated, 406 were down-regulated and 90% were affected only by a single species of radiation. A novel statistical clustering technique identified the regulatory relationships between the radiation-modulated genes and showed that genes affected by each radiation species were associated with unique regulatory clusters. This suggests that independent homeostatic mechanisms are activated in response to radiation exposure as a function of track structure or ionization density.

Nelson, Gregory A.; Jones, Tamako A.; Chesnut, Aaron; Smith, Anna L.

2002-01-01

323

A Nonhuman Primate Model of Human Radiation-Induced Venocclusive Liver Disease and Hepatocyte Injury  

SciTech Connect

Background: Human liver has an unusual sensitivity to radiation that limits its use in cancer therapy or in preconditioning for hepatocyte transplantation. Because the characteristic veno-occlusive lesions of radiation-induced liver disease do not occur in rodents, there has been no experimental model to investigate the limits of safe radiation therapy or explore the pathogenesis of hepatic veno-occlusive disease. Methods and Materials: We performed a dose-escalation study in a primate, the cynomolgus monkey, using hypofractionated stereotactic body radiotherapy in 13 animals. Results: At doses ?40 Gy, animals developed a systemic syndrome resembling human radiation-induced liver disease, consisting of decreased albumin, elevated alkaline phosphatase, loss of appetite, ascites, and normal bilirubin. Higher radiation doses were lethal, causing severe disease that required euthanasia approximately 10 weeks after radiation. Even at lower doses in which radiation-induced liver disease was mild or nonexistent, latent and significant injury to hepatocytes was demonstrated by asialoglycoprotein-mediated functional imaging. These monkeys developed hepatic failure with encephalopathy when they received parenteral nutrition containing high concentrations of glucose. Histologically, livers showed central obstruction via an unusual intimal swelling that progressed to central fibrosis. Conclusions: The cynomolgus monkey, as the first animal model of human veno-occlusive radiation-induced liver disease, provides a resource for characterizing the early changes and pathogenesis of venocclusion, for establishing nonlethal therapeutic dosages, and for examining experimental therapies to minimize radiation injury.

Yannam, Govardhana Rao [Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska (United States); Han, Bing [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania (United States); Department of Hepatobiliary Surgery, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi (China); Setoyama, Kentaro [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania (United States); Yamamoto, Toshiyuki [Department of Surgery, University of Nebraska Medical Center, Omaha, Nebraska (United States); Ito, Ryotaro; Brooks, Jenna M. [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania (United States); Guzman-Lepe, Jorge [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania (United States); Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania (United States); Galambos, Csaba [Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania (United States); Fong, Jason V. [Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania (United States); Deutsch, Melvin; Quader, Mubina A. [Department of Radiation Oncology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania (United States); Yamanouchi, Kosho [Department of Radiation Oncology, Albert Einstein College of Medicine, Bronx, New York (United States); Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York (United States); Kabarriti, Rafi; Mehta, Keyur [Department of Radiation Oncology, Albert Einstein College of Medicine, Bronx, New York (United States); Soto-Gutierrez, Alejandro [Department of Pathology, Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania (United States); McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania (United States); and others

2014-02-01

324

Efficacy of radioprotection in the prevention of radiation-induced craniofacial bone growth inhibition.  

PubMed

It has been reported that radiotherapy-induced craniofacial deformities can occur in 66 to 100 percent of survivors of childhood head and neck cancers. Recent interest in the effectiveness of radioprotectors in the protection of normal tissue against radiation injury led us to investigate a possible role of radioprotection in the prevention of radiation-induced craniofacial bone growth inhibition. Therefore, the objective of this study was to use the radioprotective agent amifostine (Ethyol, WR-2721) as a probe to determine the effectiveness of radioprotection in the prevention of radiation-induced craniofacial bone growth inhibition after single-dose orthovoltage radiation to the infant rabbit orbital-zygomatic complex. Seven-week-old male New Zealand white rabbits were randomized into three groups (n = 10 each): group 1, 0 Gy (sham radiation); group 2, 35-Gy single-dose orthovoltage radiation; and group 3, 35-Gy single-dose orthovoltage radiation and amifostine (300 mg/kg intravenously, given 20 minutes before radiation). Serial radiographs and computed tomographic scans were obtained for cephalometric analysis, bone volume, and bone density measurements until skeletal maturity at 21 weeks. Significant (p < 0.05) reductions in orbital-zygomatic complex linear bone growth, bone volume, and bone density were observed after 35-Gy radiation compared with nonirradiated controls. No significant differences were noted between groups in cephalometric analysis of the nontreated (nonirradiated) left orbital-zygomatic complex, indicating no crossover effect from the radiation beam. However, pretreatment with amifostine, 20 minutes before 35-Gy radiation, resulted in significant (p < 0.05) preservation of linear bone growth, bone volume, and bone mineral density in the rabbit orbital-zygomatic complex compared with controls. This study demonstrated for the first time the effectiveness of a radioprotector in the prevention of radiation-induced craniofacial bone growth inhibition, and it paves the way for investigation into the pathogenic mechanism and prevention of radiotherapy-induced craniofacial deformities. PMID:11964983

Forrest, Christopher R; O'Donovan, David A; Yeung, Ivan; Zeman, Vlado; La Scala, Giorgio; Neligan, Peter C; Pang, Cho Y

2002-04-01

325

Poly lactic acid based foams prepared via thermally induced phase separation (TIPS): A method to tune the crystallinity  

NASA Astrophysics Data System (ADS)

Blends of Poly-L-Lactic Acid (PLLA) with two Poly-Lactic Acid (PLA) in different proportions (90/10 and 70/30) were utilized in order to produce biodegradable and biocompatible scaffolds for soft tissue engineering applications. The scaffolds were produced via thermally induced phase separation (TIPS) starting from ternary systems where dioxane was the solvent and water the non-solvent. Morphology was evaluated by Scanning Electron Microscopy (average pore size and interconnection). Moreover a DSC analysis was carried out on the as-obtained scaffold in order to obtain information about theirs thermal properties (enthalpy of melt and crystallization). The results showed that is possible to prepare scaffolds of PLLA/PLA via TIPS. Moreover, the PLA seems to influences the TIPS process in terms of demixing temperatures. The data confirm that the morphology and the mechanical properties of the scaffold can be tuned, starting from PLLA blends and using PLA with different molecular weights.

Pavia, Francesco Carf?; La Carrubba, Vincenzo; Brucato, Valerio

2012-07-01

326

Synchrotron-Radiation Induced X-Ray Emission (SRIXE)  

SciTech Connect

Elemental analysis using emission of characteristic x rays is a well-established scientific method. The success of this analytical method is highly dependent on the properties of the source used to produce the x rays. X-ray tubes have long existed as a principal excitation source, but electron and proton beams have also been employed extensively. The development of the synchrotron radiation x-ray source that has taken place during the past 40 years has had a major impact on the general field of x-ray analysis. Even tier 40 years, science of x-ray analysis with synchrotron x-ray beams is by no means mature. Improvements being made to existing synchrotron facilities and the design and construction of new facilities promise to accelerate the development of the general scientific use of synchrotron x-ray sources for at least the next ten years. The effective use of the synchrotron source technology depends heavily on the use of high-performance computers for analysis and theoretical interpretation of the experimental data. Fortunately, computer technology has advanced at least as rapidly as the x-ray technology during the past 40 years and should continue to do so during the next decade. The combination of these technologies should bring about dramatic advances in many fields where synchrotron x-ray science is applied. It is interesting also to compare the growth and rate of acceptance of this particular research endeavor to the rates for other technological endeavors. Griibler [1997] cataloged the time required for introduction, diffusion,and acceptance of technological, economic, and social change and found mean values of 40 to 50 years. The introduction of the synchrotron source depends on both technical and non-technical factors, and the time scale at which this seems to be occurring is quite compatible with what is seen for other major innovations such as the railroad or the telegraph. It will be interesting to see how long the present rate of technological change and increase in scientific use can be maintained for the synchrotron x-ray source. A short summary of the present state of the synchrotron radiation-induced x-ray emission (SRIXE) method is presented here. Basically, SRIXE experiments can include any that depend on the detection. of characteristic x-rays produced by the incident x-ray beam born the synchrotron source as they interact with a sample. Thus, experiments done to measure elemental composition, chemical state, crystal, structure, and other sample parameters can be considered in a discussion of SRIXE. It is also clear that the experimentalist may well wish to use a variety of complementary techniques for study of a given sample. For this reason, discussion of computed microtomography (CMT) and x-ray diffraction is included here. It is hoped that this present discussion will serve as a succinct introduction to the basic ideas of SRIXE for those not working in the field and possibly help to stimulate new types of work by those starting in the field as well as by experienced practitioners of the art. The topics covered include short descriptions of (1) the properties of synchrotron radiation, (2) a description of facilities used for its production, (3) collimated microprobe, (4) focused microprobes, (5) continuum and monoenergetic excitation, (6) detection limits, (7) quantitation, (8) applications of SRIXE, (9) computed microtomography (CMT), and (10)chemical speciation using x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS). An effort has been made to cite a wide variety of work from different laboratories to show the vital nature of the field.

Jones, Keith W.

1999-09-01

327

Molecular responses of radiation-induced liver damage in rats.  

PubMed

The aim of the present study was to investigate the molecular responses involved in radiation?induced liver damage (RILD). Sprague?Dawley rats (6?weeks?old) were irradiated once at a dose of 20 Gy to the right upper quadrant of the abdomen. The rats were then sacrificed 3 days and 1, 2, 4, 8 and 12 weeks after irradiation and rats, which were not exposed to irradiation were used as controls. Weight measurements and blood was obtained from the rats and liver tissues were collected for histological and apoptotic analysis. Immunohistochemistry, reverse transcription quantitative polymerase chain reaction (RT?qPCR) and western blot analysis were performed to measure the expression levels of mRNAs and proteins, respectively. The serum levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were increased significantly in the RILD rats. Histological investigation revealed the proliferation of collagen and the formation of fibrotic tissue 12 weeks after irradiation. Apoptotic cells were observed predominantly 2 and 4 weeks after irradiation. The immunohistochemistry, RT?qPCR and western blot analysis all revealed the same pattern of changes in the expression levels of the molecules assessed. The expression levels of transforming growth factor??1 (TGF??1), nuclear factor (NF)??B65, mothers against decapentaplegic homolog 3 (Smad3) and Smad7 and connective tissue growth factor were increased during the recovery period following irradiation up to 12 weeks. The expression levels of tumor necrosis factor??, Smad7 and Smad4 were only increased during the early phase (first 4 weeks) of recovery following irradiation. In the RILD rat model, the molecular responses indicated that the TGF??1/Smads and NF??B65 signaling pathways are involved in the mechanism of RILD recovery. PMID:25483171

Cheng, Wei; Xiao, Lei; Ainiwaer, Aimudula; Wang, Yunlian; Wu, Ge; Mao, Rui; Yang, Ying; Bao, Yongxing

2015-04-01

328

Molecular responses of radiation-induced liver damage in rats  

PubMed Central

The aim of the present study was to investigate the molecular responses involved in radiation-induced liver damage (RILD). Sprague-Dawley rats (6-weeks-old) were irradiated once at a dose of 20 Gy to the right upper quadrant of the abdomen. The rats were then sacrificed 3 days and 1, 2, 4, 8 and 12 weeks after irradiation and rats, which were not exposed to irradiation were used as controls. Weight measurements and blood was obtained from the rats and liver tissues were collected for histological and apoptotic analysis. Immunohistochemistry, reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were performed to measure the expression levels of mRNAs and proteins, respectively. The serum levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were increased significantly in the RILD rats. Histological investigation revealed the proliferation of collagen and the formation of fibrotic tissue 12 weeks after irradiation. Apoptotic cells were observed predominantly 2 and 4 weeks after irradiation. The immunohistochemistry, RT-qPCR and western blot analysis all revealed the same pattern of changes in the expression levels of the molecules assessed. The expression levels of transforming growth factor-?1 (TGF-?1), nuclear factor (NF)-?B65, mothers against decapentaplegic homolog 3 (Smad3) and Smad7 and connective tissue growth factor were increased during the recovery period following irradiation up to 12 weeks. The expression levels of tumor necrosis factor-?, Smad7 and Smad4 were only increased during the early phase (first 4 weeks) of recovery following irradiation. In the RILD rat model, the molecular responses indicated that the TGF-?1/Smads and NF-?B65 signaling pathways are involved in the mechanism of RILD recovery. PMID:25483171

CHENG, WEI; XIAO, LEI; AINIWAER, AIMUDULA; WANG, YUNLIAN; WU, GE; MAO, RUI; YANG, YING; BAO, YONGXING

2015-01-01

329

Radiation-induced grafting of acrylic acid onto polyethylene filaments  

NASA Astrophysics Data System (ADS)

Radiation-induced grafting of acrylic acid onto high density polyethylene (PE) filaments was carried out in order to raise softening temperature and impart flame retardance and hydrophilic properties. Mutual ?-irradiation method was employed for the grafting in a mixture of acrylic acid (AA), ethylene dichloride and water containing a small amount of ferrous ammonium sulfate. The rate of grafting was very low at room temperature. On the other hand, large percent grafts were obtained when the grafting was performed at an elevated temperature. Activation energy for the initial rate of grafting was found to be 17 {kcal}/{mol} between 20 and 60°C and 10 {kcal}/{mol} between 60 and 80°C. Original PE filament begins to shrink at 70°C, show maximum shrinkage of 50% at 130°C and then breaks off at 136°C. When a 34% AA graft is converted to metallic salt such as sodium and calcium, the graft filament retains its filament form even above 300°C and gives maximum shrinkage of 15%. Burning tests by a wire-netting basket method indicate that graft filaments and its metallic salts do not form melting drops upon burning and are self-extinguishing. Original PE filament shows no moisture absorption, however, that of AA-grafted PE increases with increasing graft percent. The sodium salt of 15% graft shows the same level of moisture regain as cotton. The AA-grafted PE filament and its metallic salts can be dyed with cationic dyes even at 1% graft. Tensile properties of PE filament is impaired neither by grafting nor by conversion to metallic salts.

Kaji, K.; Okada, T.; Sakurada, I.

330

Ultraviolet radiation directly induces pigment production by cultured human melanocytes  

SciTech Connect

In humans the major stimulus for cutaneous pigmentation is ultraviolet radiation (UVR). Little is known about the mechanism underlying this response, in part because of the complexity of interactions in whole epidermis. Using a recently developed culture system, human melanocytes were exposed daily to a physiologic range of UVR doses from a solar simulator. Responses were determined 24 hours after the last exposure. There was a dose-related increase in melanin content per cell and uptake of /sup 14/C-DOPA, accompanied by growth inhibition. Cells from donors of different racial origin gave proportionately similar increases in melanin, although there were approximately tenfold differences in basal values. Light and electron microscopy revealed UVR-stimulated increases in dendricity as well as melanosome number and degree of melanization, analogous to the well-recognized melanocyte changes following sun exposure of intact skin. Similar responses were seen with Cloudman S91 melanoma cells, although this murine cell line required lower UVR dosages and fewer exposures for maximal stimulation. These data establish that UVR is capable of directly stimulating melanogenesis. Because cyclic AMP elevation has been associated in some settings with increased pigment production by cultured melanocytes, preliminary experiments were conducted to see if the effects of UVR were mediated by cAMP. Both alpha-MSH and isobutylmethylxanthine (IBMX), as positive controls, caused a fourfold increase in cAMP level in human melanocytes and/or S91 cells, but following a dose of UVR sufficient to stimulate pigment production there was no change in cAMP level up to 4 hours after exposure. Thus, it appears that the UVR-induced melanogenesis is mediated by cAMP-independent mechanisms.

Friedmann, P.S.; Gilchrest, B.A.

1987-10-01

331

Ion beam induced luminescence (IBIL) system for imaging of radiation induced changes in materials  

NASA Astrophysics Data System (ADS)

The progress of construction on the new IBIL (ion beam induced luminescence) spectrometer installed at the ion microprobe facility of the Ru?er Boškovi? Institute (RBI) is reported. The IBIL system can be used with beams from either 6.0 MV Tandem Van de Graaff or 1.0 MV Tandetron accelerators. Components of the new apparatus and current experimental set-up are described in detail. Measurements with the new IBIL system were performed using a 2 MeV proton microbeam on three sets of samples. This paper gives a summary of the IBIL arrangement capabilities for various problems, emphasising the potential of this technique for radiation damage studies. Due to the relatively good sensitivity of the IBIL spectrometer, integration into the conventional ion beam analysis (IBA) microbeam setup is shown to be possible.

Markovi?, N.; Siketi?, Z.; Cosic, D.; Jung, H. K.; Lee, N. H.; Han, W.-T.; Jakši?, M.

2015-01-01

332

Irradiated Esophageal Cells are Protected from Radiation-Induced Recombination by MnSOD Gene Therapy  

E-print Network

Radiation-induced DNA damage is a precursor to mutagenesis and cytotoxicity. During radiotherapy, exposure of healthy tissues can lead to severe side effects. We explored the potential of mitochondrial SOD (MnSOD) gene ...

Niu, Yunyun

333

Quantitative model of radiation induced charge trapping in SiO2  

Microsoft Academic Search

A predictive model of radiation induced oxide charging, thermodynamics and electron spin resonance measurements of defects known as E' centers, has been developed. The model is successfully tested on 60Co irradiated MOSFETs

P. M. Lenahan; B. D. Wallace; P. Cole

1997-01-01

334

Sodium bicarbonate induces crystalline wax generation, activates host-resistance, and increases imazalil level in rind wounds of oranges, improving the control of green mold during storage.  

PubMed

Imazalil (IMZ) was quantified in the flavedo and albedo (Citrus fruits outer and inner tissue of the exocarp) of wounded and unwounded Valencia L. Olinda oranges following a 2 min immersion at 25 degrees C in 50, 100, or 250 microg mL(-1) of the fungicide mixture with or without 3% sodium bicarbonate (SBC). The addition of SBC significantly reduced the decay incidence throughout 30 d of storage at 10 degrees C with 95% RH and 6 d of simulated marketing period at 25 degrees C and 75% RH. In unwounded oranges, IMZ uptake was not changed by the coapplication of SBC, and the fungicide was predominantly recovered in the flavedo. To the contrary, in the albedo of wounded fruit, the residue level increased by about 6-fold when the fungicide was applied with SBC. When SBC was coapplied to wounded fruit, the phytoalexin scoparone was induced in the albedo and the accumulation was not affected by IMZ. When fruit was treated with SBC, scanning electron microscopy observations evidenced a production of crystalline wax patches with branched stripes and the magnitude was positively correlated to the salt concentration in the mixture. The generation as fast as 24 h post-treatment, and the different morphology of the new wax suggests a displacement of intracuticular waxes which can affect the fungicide sorption and diffusion coefficient into the rind. PMID:20486661

Dore, Antonio; Molinu, Maria Giovanna; Venditti, Tullio; D'Hallewin, Guy

2010-06-23

335

Response of advanced bipolar processes to ionizing radiation  

Microsoft Academic Search

Ionizing radiation induced gain degradation in microcircuit bipolar polysilicon and crystalline emitter transistors is investigated. In this work, 60Co irradiation testing was performed on bipolar test structures. The effects of collector bias, dose rate, and anneal temperature are discussed. Major differences in the radiation response of polysilicon emitter transistors are demonstrated as a function of dose rate. The worst-case gain

Edward W. Enlow; Ronald L. Pease; William Combs; Ron D. Schrimpf; R. Nathan Nowlin

1991-01-01

336

Gamma radiation induced effects in floppy and rigid Ge-containing chalcogenide thin films  

NASA Astrophysics Data System (ADS)

We explore the radiation induced effects in thin films from the Ge-Se to Ge-Te systems accompanied with silver radiation induced diffusion within these films, emphasizing two distinctive compositional representatives from both systems containing a high concentration of chalcogen or high concentration of Ge. The studies are conducted on blanket chalcogenide films or on device structures containing also a silver source. Data about the electrical conductivity as a function of the radiation dose were collected and discussed based on material characterization analysis. Raman Spectroscopy, X-ray Diffraction Spectroscopy, and Energy Dispersive X-ray Spectroscopy provided us with data about the structure, structural changes occurring as a result of radiation, molecular formations after Ag diffusion into the chalcogenide films, Ag lateral diffusion as a function of radiation and the level of oxidation of the studied films. Analysis of the electrical testing suggests application possibilities of the studied devices for radiation sensing for various conditions.

Ailavajhala, Mahesh S.; Gonzalez-Velo, Yago; Poweleit, Christian; Barnaby, Hugh; Kozicki, Michael N.; Holbert, Keith; Butt, Darryl P.; Mitkova, Maria

2014-01-01

337

Gamma radiation induced effects in floppy and rigid Ge-containing chalcogenide thin films  

SciTech Connect

We explore the radiation induced effects in thin films from the Ge-Se to Ge-Te systems accompanied with silver radiation induced diffusion within these films, emphasizing two distinctive compositional representatives from both systems containing a high concentration of chalcogen or high concentration of Ge. The studies are conducted on blanket chalcogenide films or on device structures containing also a silver source. Data about the electrical conductivity as a function of the radiation dose were collected and discussed based on material characterization analysis. Raman Spectroscopy, X-ray Diffraction Spectroscopy, and Energy Dispersive X-ray Spectroscopy provided us with data about the structure, structural changes occurring as a result of radiation, molecular formations after Ag diffusion into the chalcogenide films, Ag lateral diffusion as a function of radiation and the level of oxidation of the studied films. Analysis of the electrical testing suggests application possibilities of the studied devices for radiation sensing for various conditions.

Ailavajhala, Mahesh S.; Mitkova, Maria [Department of Electrical Engineering, Boise State University, 1910 University Dr. Boise, Idaho 83725-2075 (United States); Gonzalez-Velo, Yago; Barnaby, Hugh; Kozicki, Michael N.; Holbert, Keith [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287-9309 (United States); Poweleit, Christian [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Butt, Darryl P. [Department of Material Science and Engineering, Boise State University, 1910 University Dr. Boise, Idaho 83725-2090 (United States)

2014-01-28

338

Modeling the anneal of radiation-induced trapped holes in a varying thermal environment  

Microsoft Academic Search

The anneal of radiation-induced trapped holes in MOS transistors is found to be thermally activated. A quantitative, physical model based on thermal emission and tunneling is developed. It accurately predicts the anneal of radiation-induced trapped holes in constant or time-varying thermal environments. Data are presented which quantitatively verify the accuracy of the model for temperatures between 25 and 160°C. This

P. J. McWhorter; S. L. Miller; W. M. Miller

1990-01-01

339

Ceramide Biogenesis Is Required for Radiation-Induced Apoptosis in the Germ Line of C. elegans  

Microsoft Academic Search

Ceramide engagement in apoptotic pathways has been a topic of controversy. To address this controversy, we tested loss-of-function (lf) mutants of conserved genes of sphingolipid metabolism in Caenorhabditis elegans. Although somatic (developmental) apoptosis was unaffected, ionizing radiation-induced apoptosis of germ cells was obliterated upon inactivation of ceramide synthase and restored upon microinjection of long-chain natural ceramide. Radiation-induced increase in the

Xinzhu Deng; Xianglei Yin; Richard Allan; Diane D. Lu; Carine W. Maurer; Adriana Haimovitz-Friedman; Zvi Fuks; Shai Shaham; Richard Kolesnick

2008-01-01

340

Application of Formaldehyde for Treatment of Hemorrhagic Radiation-Induced Proctitis  

Microsoft Academic Search

. Radiation-induced proctitis with hemorrhage is not a common complication of radiotherapy to the pelvis for carcinoma.\\u000a In the most severe forms, massive hemorrhage may necessitate repeated transfusions and inpatient treatment. In severe cases\\u000a medical treatment has not been proved effective. Surgery may lead to serious complications and is technically difficult. Six\\u000a patients who showed a hemorrhagic radiation-induced proctitis have

B. Roche; R. Chautems; M. C. Marti

1996-01-01

341

Effect of bias on radiation-induced paramagnetic defects at the silicon-silicon dioxide interface  

Microsoft Academic Search

Electron spin resonance measurements have been made on gamma-irradiated (111) Si\\/SiO2 structures as a function of bias across the oxide. We observe a large change in the density of radiation-induced paramagnetic Pb centers with bais. We conclude that Pb defects (trivalent silicons at the Si\\/SiO2 interface) account for a very large portion of the radiation-induced interface states.

P. M. Lenahan; P. V. Dressendorfer

1982-01-01

342

Ice-induced enhancement of solar radiation beneath overcast skies near Antarctica  

E-print Network

ICE-INDUCED ENHANCEMENT OF SOLAR RADIATION BENEATH OVERCAST SKIES NEAR ANTARCTICA A Thesis by NICHOLAS CHARLES HORVATH Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIFNCE May 1981 Major Subject: Meteorology ICE-INDUCED ENHANCEMENT OF SOLAR RADIATION BENEATH OVERCAST SKIES NEAR ANTARCTICA A Thesis by NICHOLAS CHARLES HORVATH Approsed as to style and content by: (Ch irman of Committee) (Member...

Horvath, Nicholas Charles

1981-01-01

343

Idiopathic and Radiation-Induced Ocular Telangiectasia: The Involvement of the ATM Gene  

Microsoft Academic Search

PURPOSE. To investigate whether individuals, with no family history of ataxia telangiectasia (AT), in whom idiopathic or radiation-induced ocular telangiectasia developed are carriers of ATM gene mutations. METHODS. The ATM cDNA from lymphoblastoid cell lines estab- lished from 16 patients with idiopathic retinal or choroidal telan- giectasia and 14 patients with radiation-induced telangiectasia after radiotherapy for age-related macular degeneration (AMD)

Martine Mauget-Faysse; Michele Vuillaume; Maddalena Quaranta; Norman Moullan; Sandra Angele; Marlin D. Friesen; Janet Hall

2003-01-01

344

Exposure to heavy ion radiation induces persistent oxidative stress in mouse intestine.  

PubMed

Ionizing radiation-induced oxidative stress is attributed to generation of reactive oxygen species (ROS) due to radiolysis of water molecules and is short lived. Persistent oxidative stress has also been observed after radiation exposure and is implicated in the late effects of radiation. The goal of this study was to determine if long-term oxidative stress in freshly isolated mouse intestinal epithelial cells (IEC) is dependent on radiation quality at a dose relevant to fractionated radiotherapy. Mice (C57BL/6J; 6 to 8 weeks; female) were irradiated with 2 Gy of ?-rays, a low-linear energy transfer (LET) radiation, and intestinal tissues and IEC were collected 1 year after radiation exposure. Intracellular ROS, mitochondrial function, and antioxidant activity in IEC were studied by flow cytometry and biochemical assays. Oxidative DNA damage, cell death, and mitogenic activity in IEC were assessed by immunohistochemistry. Effects of ? radiation were compared to (56)Fe radiation (iso-toxic dose: 1.6 Gy; energy: 1000 MeV/nucleon; LET: 148 keV/µm), we used as representative of high-LET radiation, since it's one of the important sources of high Z and high energy (HZE) radiation in cosmic rays. Radiation quality affected the level of persistent oxidative stress with higher elevation of intracellular ROS and mitochondrial superoxide in high-LET (56)Fe radiation compared to unirradiated controls and ? radiation. NADPH oxidase activity, mitochondrial membrane damage, and loss of mitochondrial membrane potential were greater in (56)Fe-irradiated mice. Compared to ? radiation oxidative DNA damage was higher, cell death ratio was unchanged, and mitotic activity was increased after (56)Fe radiation. Taken together our results indicate that long-term functional dysregulation of mitochondria and increased NADPH oxidase activity are major contributing factors towards heavy ion radiation-induced persistent oxidative stress in IEC with potential for neoplastic transformation. PMID:22936983

Datta, Kamal; Suman, Shubhankar; Kallakury, Bhaskar V S; Fornace, Albert J

2012-01-01

345

Exposure to Heavy Ion Radiation Induces Persistent Oxidative Stress in Mouse Intestine  

PubMed Central

Ionizing radiation-induced oxidative stress is attributed to generation of reactive oxygen species (ROS) due to radiolysis of water molecules and is short lived. Persistent oxidative stress has also been observed after radiation exposure and is implicated in the late effects of radiation. The goal of this study was to determine if long-term oxidative stress in freshly isolated mouse intestinal epithelial cells (IEC) is dependent on radiation quality at a dose relevant to fractionated radiotherapy. Mice (C57BL/6J; 6 to 8 weeks; female) were irradiated with 2 Gy of ?-rays, a low-linear energy transfer (LET) radiation, and intestinal tissues and IEC were collected 1 year after radiation exposure. Intracellular ROS, mitochondrial function, and antioxidant activity in IEC were studied by flow cytometry and biochemical assays. Oxidative DNA damage, cell death, and mitogenic activity in IEC were assessed by immunohistochemistry. Effects of ? radiation were compared to 56Fe radiation (iso-toxic dose: 1.6 Gy; energy: 1000 MeV/nucleon; LET: 148 keV/µm), we used as representative of high-LET radiation, since it's one of the important sources of high Z and high energy (HZE) radiation in cosmic rays. Radiation quality affected the level of persistent oxidative stress with higher elevation of intracellular ROS and mitochondrial superoxide in high-LET 56Fe radiation compared to unirradiated controls and ? radiation. NADPH oxidase activity, mitochondrial membrane damage, and loss of mitochondrial membrane potential were greater in 56Fe-irradiated mice. Compared to ? radiation oxidative DNA damage was higher, cell death ratio was unchanged, and mitotic activity was increased after 56Fe radiation. Taken together our results indicate that long-term functional dysregulation of mitochondria and increased NADPH oxidase activity are major contributing factors towards heavy ion radiation-induced persistent oxidative stress in IEC with potential for neoplastic transformation. PMID:22936983

Datta, Kamal; Suman, Shubhankar; Kallakury, Bhaskar V. S.; Fornace, Albert J.

2012-01-01

346

Defect formation induced by seed-joints during directional solidification of quasi-mono-crystalline silicon ingots  

NASA Astrophysics Data System (ADS)

In this work, the growth behavior inside and above seed gaps during directional solidification of monocrystalline lab-scale silicon ingots was investigated. It will be shown that the silicon melt fills the gaps rapidly and monocrystalline growth starts in most cases at the seed side walls toward the gap center. During this process, dislocations were induced at the seed edges and in the gap center by the thermal shock caused by the hot melt and the coalescence of the two growth interfaces, respectively. The dislocations originating from the gap are propagating more or less parallel to the growth axis toward the top of the crystal. These dislocation bundles fan out in dependence of the growth height and axial seed orientation, respectively. It was found that <1 0 0> is the most suitable growth direction in comparison to <1 1 1> and <1 1 0> to avoid defect clusters above the seed gaps which is probably due to the orientation of the preferential glide systems.

Trempa, M.; Reimann, C.; Friedrich, J.; Müller, G.; Krause, A.; Sylla, L.; Richter, T.

2014-11-01

347

Mechanism of calcium disilicide-induced calcification of crystalline silicon surfaces in simulated body fluid under zero bias.  

PubMed

A dry-etch spark ablation method was used to produce calcium disilicide (CaSi2/Si) layers on silicon surfaces, and their biomineralization under zero bias was followed by means of scanning electron microscopy, X-ray energy dispersive analysis, and Raman spectroscopy. CaSi2/Si wafers are bioinert at 25 degrees C and bioactive at 37 degrees C. Mechanistic insights regarding biomineralization were derived from an analysis of film growth morphology and chemical composition after various soaking periods in standard simulated body fluid (SBF). Changes in CaSi2/Si calcification behavior as a function of reaction temperature and pH, SBF concentration, and various surface modification processes were also employed for this purpose. During CaSi2/Si calcification under zero bias, calcium phosphate (CaP) growth is strongly dependent on the structural degradation of CaSi2/Si grains. Surface silanol groups, initially present on the as-prepared material, cannot induce CaP nucleation, which begins only upon delamination of CaSi2/Si layers. The calcium phosphate phases, which are present during various growth stages, possibly include a combination of Mg-substituted whitlockite, monetite, and tricalcium phosphate. PMID:18080303

Seregin, Vladimir V; Coffer, Jeffery L

2008-10-01

348

A model of radiation induced leakage current (RILC) in ultra-thin gate oxides  

Microsoft Academic Search

An analytical model of Radiation Induced Leakage Current (RILC) has been developed for ultra-thin gate oxides submitted to high dose ionizing radiation. The model is based on the solution of the Schrodinger equation for a simplified oxide band structure, where RILC occurs through electron trap-assisted tunneling. The values of the model parameters have been calibrated by comparing the transmission probabilities

L. Larcher; A. Paccagnella; M. Ceschia; G. Ghidini

1999-01-01

349

Development of an in vitro model for radiation-induced effects on oral keratinocytes  

Microsoft Academic Search

Changes in epithelial cell activity and the production of pro-inflammatory cytokines were examined utilizing an organotypic culture system as an in vitro model to study the effects of radiation on oral keratinocytes to simulate what is thought to occur in radiation-induced oral mucositis. Monolayer cultures of oral keratinocyte were irradiated by varying the dose. Cell injury was assessed using a

T. Tobita; K. Izumi; S. E. Feinberg

2010-01-01

350

Enhanced connement discharges in DIII-D with neon and argon induced radiation  

E-print Network

Enhanced con®nement discharges in DIII-D with neon and argon induced radiation G.L. Jackson a,*, M in the DIII-D tokamak with neon and argon gas pung. These radiating mantle enhanced con®nement discharges have operations; Neon; Graphite 1. Introduction Reactor operating scenarios where a substantial fraction

California at San Diego, University of

351

Radiation-induced meningioma after treatment for pituitary adenoma: Case report and literature review  

SciTech Connect

Radiation-induced meningiomas are becoming increasingly well-recognized. We report a case of a 35-year-old man who developed a suprasellar meningioma 9 years after receiving a radiation dose of 4480 cGy for a pituitary adenoma. The literature is also reviewed. 10 references.

Partington, M.D.; Davis, D.H. (Mayo Clinic, Rochester, MN (USA))

1990-02-01

352

Repression of ATR pathway by miR-185 enhances radiation-induced apoptosis and proliferation  

E-print Network

OPEN Repression of ATR pathway by miR-185 enhances radiation-induced apoptosis and proliferation of a human microRNA (miRNA), hsa-miR-185, is downregulated in response to ionizing radiation. Elevation of miR damage and DNA replication stresses, is a target of miR-185. This prediction was validated by luciferase

Cai, Long

353

Neoplasms induced by megavoltage radiation in the head and neck region  

Microsoft Academic Search

Radiation-induced cancer, although fortunately a rare complication of radiotherapy, is nonetheless observed occasionally even after megavoltage radiation has been used. Over a 22-year period at the Curie Institute, four patients were found to have malignant neoplasms within the fields of megavoltage treatment given for various cancers of the head and neck region. Three of the neoplasms were sarcomas, two osteogenic

R. A. Steeves; J. P. Bataini

1981-01-01

354

Measurements of the Radiation Induced Conductivity of Insulating Polymeric Materials for the James Webb Space Telescope  

Microsoft Academic Search

We report on initial measurements of Radiation Induced Conductivity (RIC) for twelve thin film polymer materials that are used in the cabling of the James Webb Space Telescope. Results will be used to model possible detrimental arching due to space craft charging effects. RIC occurs when incident ionizing radiation deposits energy in a material and excites electrons into the conduction

J. Corbridge; J. R. Dennison; J. Hodges; R. C. Hoffmann; J. Abbott; A. Hunt; R. Spaulding

2006-01-01

355

Homeopathic treatment of radiation-induced itching in breast cancer patients. A prospective observational study  

Microsoft Academic Search

Following surgery for carcinoma of the breast, patients receive local radiotherapy. This can cause itching, which may be severe, in the radiation field. The affected skin usually is dry, rough and red. Twenty-five patients were treated homeopathically for radiation-induced itching. Fourteen patients developed itching during their course of postoperative radiation at 27 days median (range: 14–40). Eleven patients experienced itching

O Schlappack

2004-01-01

356

Irradiated esophageal cells are protected from radiation-induced recombination by MnSOD gene therapy.  

PubMed

Radiation-induced DNA damage is a precursor to mutagenesis and cytotoxicity. During radiotherapy, exposure of healthy tissues can lead to severe side effects. We explored the potential of mitochondrial SOD (MnSOD) gene therapy to protect esophageal, pancreatic and bone marrow cells from radiation-induced genomic instability. Specifically, we measured the frequency of homologous recombination (HR) at an integrated transgene in the Fluorescent Yellow Direct Repeat (FYDR) mice, in which an HR event can give rise to a fluorescent signal. Mitochondrial SOD plasmid/liposome complex (MnSOD-PL) was administered to esophageal cells 24 h prior to 29 Gy upper-body irradiation. Single cell suspensions from FYDR, positive control FYDR-REC, and negative control C57BL/6NHsd (wild-type) mouse esophagus, pancreas and bone marrow were evaluated by flow cytometry. Radiation induced a statistically significant increase in HR 7 days after irradiation compared to unirradiated FYDR mice. MnSOD-PL significantly reduced the induction of HR by radiation at day 7 and also reduced the level of HR in the pancreas. Irradiation of the femur and tibial marrow with 8 Gy also induced a significant increase in HR at 7 days. Radioprotection by intraesophageal administration of MnSOD-PL was correlated with a reduced level of radiation-induced HR in esophageal cells. These results demonstrate the efficacy of MnSOD-PL for suppressing radiation-induced HR in vivo. PMID:20334517

Niu, Yunyun; Wang, Hong; Wiktor-Brown, Dominika; Rugo, Rebecca; Shen, Hongmei; Huq, M Saiful; Engelward, Bevin; Epperly, Michael; Greenberger, Joel S

2010-04-01

357

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

NASA Astrophysics Data System (ADS)

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

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

358

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

PubMed Central

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. PMID:25324981

Jenrow, Kenneth A.; Brown, Stephen L.

2014-01-01

359

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

NASA Technical Reports Server (NTRS)

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

Morgan, William F.

2003-01-01

360

Early mechanisms in radiation-induced biological damage  

SciTech Connect

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. (ACR)

Powers, E.L.

1983-01-01

361

Gamma Radiation Induced Calibration Shift for Four Cryogenic Thermometer Types  

Microsoft Academic Search

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

S. Scott Courts; C. J. Yeager

2004-01-01

362

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

NASA Technical Reports Server (NTRS)

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

Hada, Megumi; Cucinotta, Francis; Wu, Honglu

2009-01-01

363

Radiation-induced mechanical property changes in filled rubber  

SciTech Connect

In a recent paper we exposed a filled elastomer to controlled radiation dosages and explored changes in its cross-link density and molecular weight distribution between network junctions [A. Maiti et al., Phys. Rev. E 83, 031802 (2011)]. Here we report mechanical response measurements when the material is exposed to radiation while being under finite nonzero strain. We observe interesting hysteretic behavior and material softening representative of the Mullins effect, and materials hardening due to radiation. The net magnitude of the elastic modulus depends upon the radiation dosage, strain level, and strain-cycling history of the material. Using the framework of Tobolsky's two-stage independent network theory we develop a model that can quantitatively interpret the observed elastic modulus and its radiation and strain dependence.

Maiti, A.; Weisgraber, T. H.; Gee, R. H.; Small, W.; Alviso, C. T.; Chinn, S. C.; Maxwell, R. S. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

2011-06-15

364

http://journals.cambridge.org Downloaded: 06 Aug 2012 IP address: 130.203.205.122 Radiation effects in crystalline ceramics for the immobilization  

E-print Network

Materials Research Society HelpCommentsWelcome Journal of MATERIALS RESEARCH #12;http in crystalline ceramics for the immobilization of high-level nuclear waste and plutonium W. J. Weber Pacific Engineering and Radiological Sciences, The University of Michigan, Ann Arbor, Michigan 48109 C. R. A. Catlow

Motta, Arthur T.

365

Macro-Bending Influence on Radiation Induced Attenuation Measurement in Optical Fibres  

E-print Network

Influence of the bending radius on the measurement of radiation induced attenuation in glass optical fibres is discussed in this paper. Radiation induced attenuation measured in two single-mode fibre types shows discrepancies when coiled around a low bending radius spool: the observed attenuation is lower than expected. A series of dedicated tests reveals that this invalid measurement is related to the displacement of the mode field towards the cladding when the fibre is bent with a low radius, and to the different radiation resistances of the core and cladding glasses. For irradiation tests of optical fibres, the spool radius should therefore be carefully chosen.

Guillermain, E; Ricci, D; Weinand, U

2014-01-01

366

Prophylaxis and management of acute radiation-induced skin reactions: a systematic review of the literature  

PubMed Central

Radiation therapy is a common treatment for cancer patients. One of the most common side effects of radiation is acute skin reaction (radiation dermatitis) that ranges from a mild rash to severe ulceration. Approximately 85% of patients treated with radiation therapy will experience a moderate-to-severe skin reaction. Acute radiation-induced skin reactions often lead to itching and pain, delays in treatment, and diminished aesthetic appearance—and subsequently to a decrease in quality of life. Surveys have demonstrated that a wide variety of topical, oral, and intravenous agents are used to prevent or to treat radiation-induced skin reactions. We conducted a literature review to identify trials that investigated products for the prophylaxis and management of acute radiation dermatitis. Thirty-nine studies met the pre-defined criteria, with thirty-three being categorized as prophylactic trials and six as management trials. For objective evaluation of skin reactions, the Radiation Therapy Oncology Group criteria and the U.S. National Cancer Institute Common Toxicity Criteria were the most commonly used tools (65% of the studies). Topical corticosteroid agents were found to significantly reduce the severity of skin reactions; however, the trials of corticosteroids evaluated various agents, and no clear indication about a preferred corticosteroid has emerged. Amifostine and oral enzymes were somewhat effective in preventing radiation-induced skin reactions in phase ii and phase iii trials respectively; further large randomized controlled trials should be undertaken to better investigate those products. Biafine cream (Ortho–McNeil Pharmaceuticals, Titusville, NJ, U.S.A.) was found not to be superior to standard regimes in the prevention of radiation-induced skin reactions (n = 6). In conclusion, the evidence is insufficient to support the use of a particular agent for the prevention and management of acute radiation-induced skin reactions. Future trials should focus on comparing agents and approaches that, in phase i and ii trials, suggest efficacy. These future phase iii randomized controlled trials must clearly distinguish between preventive and management strategies for radiation-induced dermatitis. Only then can evidence-based guidelines be developed, with the hope of standardizing the approach across centres and of improving the prevention and management of radiation-induced dermatitis. PMID:20697521

Salvo, N.; Barnes, E.; van Draanen, J.; Stacey, E.; Mitera, G.; Breen, D.; Giotis, A.; Czarnota, G.; Pang, J.; De Angelis, C.

2010-01-01

367

Naringin, a citrus flavonone, protects against radiation-induced chromosome damage in mouse bone marrow  

Microsoft Academic Search

Free radicals are responsible for the induction of damage to the cellular DNA that leads to the formation of chromosome aberrations. Antioxidants are known to scavenge free rad- icals, thereby decreasing the degree of such effects. Radi- ation is a well-known inducer of free radicals and compounds that can scavenge free radicals may reduce radiation-induced DNA damage. Naringin, a bioflavonoid

Ganesh Chandra Jagetia; V. A. Venkatesh; Tiyyagura Koti Reddy

2003-01-01

368

Mitigating the risk of radiation-induced cancers: limitations and paradigms in drug development.  

PubMed

The United States radiation medical countermeasures (MCM) programme for radiological and nuclear incidents has been focusing on developing mitigators for the acute radiation syndrome (ARS) and delayed effects of acute radiation exposure (DEARE), and biodosimetry technologies to provide radiation dose assessments for guiding treatment. Because a nuclear accident or terrorist incident could potentially expose a large number of people to low to moderate doses of ionising radiation, and thus increase their excess lifetime cancer risk, there is an interest in developing mitigators for this purpose. This article discusses the current status, issues, and challenges regarding development of mitigators against radiation-induced cancers. The challenges of developing mitigators for ARS include: the long latency between exposure and cancer manifestation, limitations of animal models, potential side effects of the mitigator itself, potential need for long-term use, the complexity of human trials to demonstrate effectiveness, and statistical power constraints for measuring health risks (and reduction of health risks after mitigation) following relatively low radiation doses (<0.75 Gy). Nevertheless, progress in the understanding of the molecular mechanisms resulting in radiation injury, along with parallel progress in dose assessment technologies, make this an opportune, if not critical, time to invest in research strategies that result in the development of agents to lower the risk of radiation-induced cancers for populations that survive a significant radiation exposure incident. PMID:24727460

Yoo, Stephen S; Jorgensen, Timothy J; Kennedy, Ann R; Boice, John D; Shapiro, Alla; Hu, Tom C-C; Moyer, Brian R; Grace, Marcy B; Kelloff, Gary J; Fenech, Michael; Prasanna, Pataje G S; Coleman, C Norman

2014-06-01

369

Cloud Induced Enhancement of Ground Level Solar Radiation  

NASA Astrophysics Data System (ADS)

Atmospheric aerosol and cloud cover are typically associated with long and short-term variability of all three solar radiation components at the ground level. Although aerosol attenuation can be a substantial factor for Direct Normal Irradiance (DNI) in some microclimates, the strongest factor for ground level irradiance attenuation is cloud cover which acts on time-scales associated with strong solar power generation fluctuations. Furthermore, the driving effects of clouds on radiative energy budgets include shortwave cooling, as a result of absorption of incoming solar radiation, and longwave heating, due to reduced emission of thermal radiation by relatively cool cloud tops. Under special circumstances, the presence of clouds in the circumsolar region may lead to the reverse; a local increase in the diffuse downwelling solar radiation due to directional scattering from clouds. This solar beam effect exceed the losses resulting from the backscattering of radiation into space. Such conditions result in radiation levels that temporarily exceed the localized clear sky values. These phenomena are referred to as Cloud Enhancement Events (CEEs). There are currently two fundamental CEE mechanisms discussed in the literature. The first involves well-defined, and optically thick cloud edges close to, but not obscuring, the solar disk. The effect here is of producing little or no change in the normal beam radiation. In this case, cloud edges in the vicinity of the sun create a non-isotropic increase in the local diffuse radiation field with respect to the isotropic scattering of a clear-sky atmosphere. The second type of CEE allows for partial or full obstruction of the solar disk by an optically thin diffuser such as fine clouds, haze or fog; which results in an enhanced but still nearly isotropic diffuse radiation field. In this study, an entire year of solar radiation data and total sky images taken at 30 second resolution at the University of California, Merced (UCM) is used in conjunction with optimized clear sky models, statistical analysis, and wavelet transform methods to investigate the solar radiation Ramp Rates (RRs) associated with both of the fundamental CEE mechanisms. Results indicate that CEEs account for nearly 5% of the total daytime hours in this dataset and produce nearly 4% of the total energy over the year. In addition, wavelet transform techniques suggest that CEEs at UCM location operate on timescales ranging from 2 to 4 minutes. Our results allow estimation of the probability and magnitude of these RRs as well the percentage of annual excess energy production resulting from CEEs which could be used to offset ancillary services required to operate PV power systems.

Inman, R.; Chu, Y.; Coimbra, C.

2013-12-01

370

Ionizing Radiation-Induced Adaptive Response in Fibroblasts under Both Monolayer and 3-Dimensional Conditions  

PubMed Central

To observe the adaptive response (AR) induced by ionizing radiation in human fibroblasts under monolayer and 3-dimensional (3-D) condition. Three kinds of fibroblasts were cultured under both monolayer and 3-D condition. Immunofluorescent staining was used to detect the ?-H2AX foci and the morphological texture. Trypan blue staining was used to detect the cell death. Western blot was used to detect the expressions of ?-H2AX, p53 and CDKN1A/p21 (p21). We found that DNA damage increased in a dose-dependent and time-dependent manner after high doses of radiation. When cells were pretreated with a priming low dose of radiation followed by high dose radiation, DNA damage was attenuated under both monolayer and 3-D condition, and the adaptive response (AR) was induced. Additionally, the morphology of cells under monolayer and 3-D conditions were different, and radiation also induced AR according to morphological texture analysis. Priming low dose radiation induced AR both under monolayer and 3-D condition. Interestingly, 3-D microenvironment made cells more sensitive to radiation. The expression of p53 and p21 was changed and indicated that they might participate in the regulation of AR. PMID:25807079

Zhao, Yinlong; Zhong, Rui; Sun, Liguang; Jia, Jie; Ma, Shumei; Liu, Xiaodong

2015-01-01

371

Management of late radiation-induced rectal injury after treatment of carcinoma of the uterus  

SciTech Connect

Sixty-one of 1418 (4.3 per cent) patients treated with radiation for carcinoma of the uterus from 1963 to 1983 had significant radiation-induced complications of the intestine develop which required a surgical opinion considering further management. Ninety-three per cent of these complications involved the rectum. Florid proctitis resolved within two years of onset in 33 per cent of the patients who were managed conservatively while 22 per cent of the patients died of disseminated disease within the same time period. Surgical treatment was eventually necessary in 39 per cent of the patients who were initially treated conservatively for radiation induced proctitis. Rectal excision with coloanal sleeve anastomosis produced a satisfactory result in eight of 11 patients with severe radiation injury involving the rectum. The incidence of radiation-induced and malignant rectovaginal fistula were similar (1 per cent), but disease-induced symptoms tended to occur earlier after primary treatment (a median of eight months) compared with radiation-induced symptoms (a median of 16 months).

Allen-Mersh, T.G.; Wilson, E.J.; Hope-Stone, H.F.; Mann, C.V.

1987-06-01

372

Detecting Radiation-Induced Injury Using Rapid 3D Variogram Analysis of CT Images of Rat Lungs  

SciTech Connect

A new heterogeneity analysis approach to discern radiation-induced lung damage was tested on CT images of irradiated rats. The method, combining octree decomposition with variogram analysis, demonstrated a significant correlation with radiation exposure levels, whereas conventional measurements and pulmonary function tests did not. The results suggest the new approach may be highly sensitive for assessing even subtle radiation-induced changes

Jacob, Rick E.; Murphy, Mark K.; Creim, Jeffrey A.; Carson, James P.

2013-10-01

373

Numerical Investigation of Radiative Heat Transfer in Laser Induced Air Plasmas  

NASA Technical Reports Server (NTRS)

Radiative heat transfer is one of the most important phenomena in the laser induced plasmas. This study is intended to develop accurate and efficient methods for predicting laser radiation absorption and plasma radiative heat transfer, and investigate the plasma radiation effects in laser propelled vehicles. To model laser radiation absorption, a ray tracing method along with the Beer's law is adopted. To solve the radiative transfer equation in the air plasmas, the discrete transfer method (DTM) is selected and explained. The air plasma radiative properties are predicted by the LORAN code. To validate the present nonequilibrium radiation model, several benchmark problems are examined and the present results are found to match the available solutions. To investigate the effects of plasma radiation in laser propelled vehicles, the present radiation code is coupled into a plasma aerodynamics code and a selected problem is considered. Comparisons of results at different cases show that plasma radiation plays a role of cooling plasma and it lowers the plasma temperature by about 10%. This change in temperature also results in a reduction of the coupling coefficient by about 10-20%. The present study indicates that plasma radiation modeling is very important for accurate modeling of aerodynamics in a laser propelled vehicle.

Liu, J.; Chen, Y. S.; Wang, T. S.; Turner, James E. (Technical Monitor)

2001-01-01

374

Inscription of optical waveguides in crystalline silicon by mid-infrared femtosecond laser pulses  

Microsoft Academic Search

For the first time to the authors' knowledge, optical waveguides have been inscribed in bulk crystalline silicon by ultrafast laser radiation. Femtosecond laser pulses of 40-nm spectral bandwidth, 1-kHz repetition rate, and 1.7-muJ on-target energy were applied at a mid-infrared wavelength of 2.4 mum to induce nonlinear absorption in the focal volume of the beam. By scanning the laser beam

Amir H. Nejadmalayeri; Peter R. Herman; Jonas Burghoff; Matthias Will; Stefan Nolte; Andreas Nnermann

2005-01-01

375

Radiation-induced apoptosis in a murine T-cell hybridoma.  

PubMed

Induction of an apoptotic cell death was studied in a mouse T-cell hybridoma. Apoptosis was induced in these cells following exposure to dexamethasone, X-radiation, 43 degrees C heat shock, A254 light, and hydrogen peroxide. In 5-Gy-exposed cells, a radiation-induced G2 phase cell cycle progression block was maximum by 8 h. The cells began to escape this progression block by 10 h. Nuclear DNA fragmentation and uptake of the vital dye trypan blue began at 12 and 14 h, respectively, and were complete by 28 h. X-radiation-induced cell death was diminished when cells were irradiated in the presence of dimethyl sulfoxide, indicating that cell death was induced by oxidative cell damage. Substitution of nuclear DNA with bromodeoxyuridine enhanced death in cells exposed to either X-radiation or A310 light, indicating that apoptosis could be induced by DNA damage. The results are consistent with radiation-induced apoptosis being stimulated by oxidative DNA damage. DNA damage stimulates a long-lived signal which controls the expression of apoptosis. Apoptosis is expressed in the G1 phase of the cell cycle subsequent to the cell irradiation. PMID:1737350

Warters, R L

1992-02-15

376

Effect of ozone oxidative preconditioning in preventing early radiation-induced lung injury in rats  

PubMed Central

Ionizing radiation causes its biological effects mainly through oxidative damage induced by reactive oxygen species. Previous studies showed that ozone oxidative preconditioning attenuated pathophysiological events mediated by reactive oxygen species. As inhalation of ozone induces lung injury, the aim of this study was to examine whether ozone oxidative preconditioning potentiates or attenuates the effects of irradiation on the lung. Rats were subjected to total body irradiation, with or without treatment with ozone oxidative preconditioning (0.72 mg/kg). Serum proinflammatory cytokine levels, oxidative damage markers, and histopathological analysis were compared at 6 and 72 h after total body irradiation. Irradiation significantly increased lung malondialdehyde levels as an end-product of lipoperoxidation. Irradiation also significantly decreased lung superoxide dismutase activity, which is an indicator of the generation of oxidative stress and an early protective response to oxidative damage. Ozone oxidative preconditioning plus irradiation significantly decreased malondialdehyde levels and increased the activity of superoxide dismutase, which might indicate protection of the lung from radiation-induced lung injury. Serum tumor necrosis factor alpha and interleukin-1 beta levels, which increased significantly following total body irradiation, were decreased with ozone oxidative preconditioning. Moreover, ozone oxidative preconditioning was able to ameliorate radiation-induced lung injury assessed by histopathological evaluation. In conclusion, ozone oxidative preconditioning, repeated low-dose intraperitoneal administration of ozone, did not exacerbate radiation-induced lung injury, and, on the contrary, it provided protection against radiation-induced lung damage. PMID:23969972

Bakkal, B.H.; Gultekin, F.A.; Guven, B.; Turkcu, U.O.; Bektas, S.; Can, M.

2013-01-01

377

Radiation-induced stenosis of the left main coronary artery  

SciTech Connect

A case of isolated left main coronary artery stenosis ten years following irradiation of the mediastinum for Hodgkin's disease is presented. Aortic biopsies were consistent with changes suggestive of radiation arteritis.

Tenet, W.; Missri, J.; Hager, D.

1986-01-01

378

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

379

Radiation-induced iodine migration in silver zeolite beds  

Microsoft Academic Search

The radiation stability of iodine-loaded, silver-exchanged zeolite (AgX) was evaluated under dynamic flow conditions. Three tests were conducted in which 1-in.-deep beds of 10 x 16 mesh AgX beads were loaded to approximately 6 mg ¹³¹I-tagged elemental iodine per mg AgX over a 1-h period. Test conditions included an intense radiation field (absorbed dose rate of approximately 1.5 x 10⁷

1978-01-01

380

Near THz radiation from optically-induced plasma sources  

Microsoft Academic Search

Summary form only given. Short pulse lasers can be used to generate two types of short-lived, radiating plasmas. When absorbed by a semiconductor, a sudden optical pulse creates a charge-neutral, electron-hole plasma that radiates as the carriers relax in local crystal, surface, or applied electric fields. When focused onto the surface of an insulator or metal, the electric fields in

F. J. Zutavern; J. V. Rudd; L. A. Mcpherson; T. R. Nelson; T. S. Luk; S. M. Cameron

2004-01-01

381

Experimental observation of laser-induced radiation heat waves  

Microsoft Academic Search

The propagation of a radiation heat wave through a thin foil of solid gold was investigated experimentally. The wave is driven by the intense thermal radiation in 1-3-mm-diam gold cavities heated by an intense laser pulse (duration 0.8-0.9 ns, wavelength 0.35 mum) to temperatures of more than 200 eV. Evidence of the propagating wave was obtained from the delayed onset

R. Sigel; G. D. Tsakiris; F. Lavarenne; J. Massen; R. Fedosejevs; J. Meyer-Ter-Vehn; M. Murakami; K. Eidmann; S. Witkowski; H. Nishimura; Y. Kato; H. Takabe; T. Endo; K. Kondo; H. Shiraga; S. Sakabe; T. Jitsuno; M. Takagi; C. Yamanaka; S. Nakai

1990-01-01

382

Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account  

SciTech Connect

The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo. (interaction of laser radiation with matter)

Kosarev, N I [Siberian Juridical Institue, Ministry of Internal Affairs, Krasnoyarsk (Russian Federation); Shaparev, N Ya [Krasnoyarsk Scientific Center, Russian Academy of Sciences, Krasnoyarsk (Russian Federation)

2006-04-30

383

Surface photoconductivity of organosilicate glass dielectrics induced by vacuum-ultraviolet radiation  

SciTech Connect

The temporary increase in the electrical surface conductivity of low-k organosilicate glass (SiCOH) during exposure to vacuum-ultraviolet radiation (VUV) is investigated. To measure the photoconductivity, patterned “comb structures” are deposited on dielectric films and exposed to synchrotron radiation in the range of 8–25 eV, which is in the energy range of most plasma vacuum-ultraviolet radiation. The change in photo surface conductivity induced by VUV radiation may be beneficial in limiting charging damage of dielectrics by depleting the plasma-deposited charge.

Zheng, H.; Nichols, M. T.; Pei, D.; Shohet, J. L. [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)] [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Nishi, Y. [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)] [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)

2013-08-14

384

Cross-talk between calcineurin/NFAT and Jak/STAT signalling induces cardioprotective ?B-crystallin gene expression in response to hypertrophic stimuli  

PubMed Central

Abstract Among the stress proteins that are up-regulated in the heart due to imposed biomechanical stress, ?B-crystallin (CryAB) is the most abundant and pivotal in rendering protection against stress-induced cell damage. Cardiomyocyte-specific expression of the CryAB gene was shown to be dependent upon an intact ?BE4 cis-element located in the CryAB enhancer. To date, there is no evidence on the identity of regulatory proteins and associated signalling molecules that control CryAB expression in cardiomyocytes. In this study, we define a mechanism by which the calcineurin/NFAT and Jak/STAT pathways regulate CryAB gene expression in response to a hypertrophic agonist endothelin-1 (En-1), in hypertrophic hearts of mice with pressure overload (TAC) and in heart-targeted calcineurin over-expressing mice (MHC-CnA). We observed that in response to various hypertrophic stimuli the transcription factors NFAT, Nished and STAT3 form a dynamic ternary complex and interact with the ?BE4 promoter element of the CryAB gene. Both dominant negative NFAT and AG490, an inhibitor of the Jak2 phosphorylation, inhibited CryAB gene transcription in transient transfection assays. AG490 was also effective in blocking the nuclear translocation of NFAT and STAT3 in cardiomyocytes treated with En-1. We observed a marked increase in CryAB gene expression in MHC-CnA mouse hearts accompanied with increased phosphorylation of STAT3. We conclude that hypertrophy-dependent CryAB gene expression can be attributed to a functional linkage between the Jak/STAT and calcineurin/NFAT signalling pathways, each of which are otherwise known to be involved independently in the deleterious outcome in cardiac hypertrophy. PMID:19538478

Manukyan, Irena; Galatioto, Josephine; Mascareno, Eduardo; Bhaduri, Sikha; Siddiqui, MAQ

2010-01-01

385

Effect of the crystallinity of silver nanoparticles on surface plasmon resonance induced enhancement of effective absorption cross-section of dyes  

NASA Astrophysics Data System (ADS)

The effective absorption cross-section of dye, and therefore, the efficiency of dye-sensitized solar cell can be increased by surface plasmon resonance (SPR) of metal nanoparticles with enhanced dephasing time. Further, the dephasing time is proportional to the enhancement factor of electric field in the vicinity of nanoparticle surface, and is governed by size, shape, and dielectric constant of surrounding medium. In this paper, we demonstrate that crystallinity of silver nanoparticles plays an important role in enhancing the dephasing time of SPR. Our theoretical formulation indicates that the dephasing time is higher for single crystalline silver nanoparticles as compared to that of polycrystalline nanoparticles, which is attributed to the presence of scattering centers in the latter. This suggests that single crystalline silver nanoparticles are interesting candidates for the enhancement of effective absorption cross-section of dyes. In order to validate our theoretical formulation, we have synthesized single crystalline and polycrystalline silver nanoparticles and studied their effect on absorption cross-section of N719 dye. We observed that dye incorporated with single crystalline silver nanoparticles showed a significant enhancement as compared to polycrystalline silver nanoparticles (24.42% in solution, 21.01% in thin film form in single crystalline silver nanoparticles while 8.52% in solution, 7.97% in thin film form in polycrystalline silver nanoparticles, respectively).

Tanvi, Mahajan, Aman; Bedi, R. K.; Kumar, Subodh; Saxena, Vibha; Aswal, D. K.

2015-02-01

386

Characterization of N-isopropyl acrylamide/acrylic acid grafted polypropylene nonwoven fabric developed by radiation-induced graft polymerization  

NASA Astrophysics Data System (ADS)

Radiation-induced graft copolymerization of N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) mixture was carried out on polypropylene nonwoven fabric to develop a thermosensitive material and has been found to affect the thermal and physical characteristics of fabric. The grafted fabrics with different monomer ratios were characterized by thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), contact angle and atomic force microscopy (AFM). Results of FTIR clearly indicated that poly(acrylic acid) and poly(N-isopropyl acrylamide) were successfully grafted onto the membrane surface. TGA results showed that the thermal stability of PP fabric increased after grafting of NIPAAm/AA. The crystallinity values from DSC and XRD were found to decrease with increase in degree of grafting because of the addition of grafted chains within the noncrystalline region. The decrease in contact angles of the grafted fabric with an increase of the degree of grafting shows that PNIPAAm/PAA exists as the hydrophilic component. The increase in surface roughness after grafting was observed by AFM.

Kumari, Mamta; Gupta, Bhuvanesh; Ikram, Saiqa

2012-11-01

387

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

NASA Astrophysics Data System (ADS)

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

Plaza-Rosado, Heriberto

1991-09-01

388

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

NASA Technical Reports Server (NTRS)

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

Plaza-Rosado, Heriberto

1991-01-01

389

A Prospective Cohort Study on Radiation-induced Hypothyroidism: Development of an NTCP Model  

SciTech Connect

Purpose: To establish a multivariate normal tissue complication probability (NTCP) model for radiation-induced hypothyroidism. Methods and Materials: The thyroid-stimulating hormone (TSH) level of 105 patients treated with (chemo-) radiation therapy for head-and-neck cancer was prospectively measured during a median follow-up of 2.5 years. Hypothyroidism was defined as elevated serum TSH with decreased or normal free thyroxin (T4). A multivariate logistic regression model with bootstrapping was used to determine the most important prognostic variables for radiation-induced hypothyroidism. Results: Thirty-five patients (33%) developed primary hypothyroidism within 2 years after radiation therapy. An NTCP model based on 2 variables, including the mean thyroid gland dose and the thyroid gland volume, was most predictive for radiation-induced hypothyroidism. NTCP values increased with higher mean thyroid gland dose (odds ratio [OR]: 1.064/Gy) and decreased with higher thyroid gland volume (OR: 0.826/cm{sup 3}). Model performance was good with an area under the curve (AUC) of 0.85. Conclusions: This is the first prospective study resulting in an NTCP model for radiation-induced hypothyroidism. The probability of hypothyroidism rises with increasing dose to the thyroid gland, whereas it reduces with increasing thyroid gland volume.

Boomsma, Marjolein J.; Bijl, Hendrik P.; Christianen, Miranda E.M.C.; Beetz, Ivo; Chouvalova, Olga; Steenbakkers, Roel J.H.M. [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Laan, Bernard F.A.M. van der [Department of Otorhinolaryngology/Head and Neck Surgery, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Wolffenbuttel, Bruce H.R. [Department of Endocrinology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands)] [Department of Endocrinology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Oosting, Sjoukje F. [Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands)] [Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Schilstra, Cornelis [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands)] [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands); Langendijk, Johannes A., E-mail: j.a.langendijk@umcg.nl [Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen (Netherlands)

2012-11-01

390

Chromatin Folding, Fragile Sites, and Chromosome Aberrations Induced by Low- and High- LET Radiation  

NASA Technical Reports Server (NTRS)

We previously demonstrated non-random distributions of breaks involved in chromosome aberrations induced by low- and high-LET radiation. To investigate the factors contributing to the break point distribution in radiation-induced chromosome aberrations, human epithelial cells were fixed in G1 phase. Interphase chromosomes were hybridized with a multicolor banding in situ hybridization (mBAND) probe for chromosome 3 which distinguishes six regions of the chromosome in separate colors. After the images were captured with a laser scanning confocal microscope, the 3-dimensional structure of interphase chromosome 3 was reconstructed at multimega base pair scale. Specific locations of the chromosome, in interphase, were also analyzed with bacterial artificial chromosome (BAC) probes. Both mBAND and BAC studies revealed non-random folding of chromatin in interphase, and suggested association of interphase chromatin folding to the radiation-induced chromosome aberration hotspots. We further investigated the distribution of genes, as well as the distribution of breaks found in tumor cells. Comparisons of these distributions to the radiation hotspots showed that some of the radiation hotspots coincide with the frequent breaks found in solid tumors and with the fragile sites for other environmental toxins. Our results suggest that multiple factors, including the chromatin structure and the gene distribution, can contribute to radiation-induced chromosome aberrations.

Zhang, Ye; Cox, Bradley; Asaithamby, Aroumougame; Chen, David J.; Wu, Honglu

2013-01-01

391

Monte Carlo Methods to Model Radiation Interactions and Induced Damage  

NASA Astrophysics Data System (ADS)

This review is devoted to the analysis of some Monte Carlo (MC) simulation programmes which have been developed to describe radiation interaction with biologically relevant materials. Current versions of the MC codes Geant4 (GEometry ANd Tracking 4), PENELOPE (PENetration and Energy Loss of Positrons and Electrons), EPOTRAN (Electron and POsitron TRANsport), and LEPTS (Low-Energy Particle Track Simulation) are described. Mean features of each model, as the type of radiation to consider, the energy range covered by primary and secondary particles, the type of interactions included in the simulation and the considered target geometries are discussed. Special emphasis lies on recent developments that, together with (still emerging) new databases that include adequate data for biologically relevant materials, bring us continuously closer to a realistic, physically meaningful description of radiation damage in biological tissues.

Muñoz, Antonio; Fuss, Martina C.; Cortés-Giraldo, M. A.; Incerti, Sébastien; Ivanchenko, Vladimir; Ivanchenko, Anton; Quesada, J. M.; Salvat, Francesc; Champion, Christophe; Gómez-Tejedor, Gustavo García

392

Studies of oxidative degradation of polymers induced by ionizing radiation  

SciTech Connect

Radiation effects on polymers in the presence of air are characterized by complicated phenomena such as dose-rate effects and post-irradiation degradation. These time-dependent effects can be understood in these terms: (1) features of the free radical chain-reaction chemistry underlying the oxidation, and (2) oxygen diffusion effects. A profiling technique has been developed to study heterogeneous degradation resulting from oxygen diffusion, and kinetic schemes have been developed to allow long-term aging predictions from short-term high dose-rate experiments. Low molecular weight additives which act either as free-radical scavengers or else as energy-scavengers are effective as stabilizers in radiation-oxidation environments. Non-radical oxidation mechanisms, involving species such as ozone, can also be important in the radiation-oxidation of polymers. 18 refs., 15 figs.

Clough, R.L.; Gillen, K.T.

1989-01-01

393

Role of Ferulic Acid in the Amelioration of Ionizing Radiation Induced Inflammation: A Murine Model  

PubMed Central

Ionizing radiation is responsible for oxidative stress by generating reactive oxygen species (ROS), which alters the cellular redox potential. This change activates several redox sensitive enzymes which are crucial in activating signaling pathways at molecular level and can lead to oxidative stress induced inflammation. Therefore, the present study was intended to assess the anti-inflammatory role of ferulic acid (FA), a plant flavonoid, against radiation-induced oxidative stress with a novel mechanistic viewpoint. FA was administered (50 mg/kg body wt) to Swiss albino mice for five consecutive days prior to exposing them to a single dose of 10 Gy 60Co ?-irradiation. The dose of FA was optimized from the survival experiment and 50 mg/kg body wt dose showed optimum effect. FA significantly ameliorated the radiation induced inflammatory response such as phosphorylation of IKK?/? and I?B? and consequent nuclear translocation of nuclear factor kappa B (NF-?B). FA also prevented the increase of cycloxygenase-2 (Cox-2) protein, inducible nitric oxide synthase-2 (iNOS-2) gene expression, lipid peroxidation in liver and the increase of tumor necrosis factor-alpha (TNF-?) and interleukin-6 (IL-6) in serum. It was observed that exposure to radiation results in decreased activity of superoxide dismutase (SOD), catalase (CAT) and the pool of reduced glutathione (GSH) content. However, FA treatment prior to irradiation increased the activities of the same endogenous antioxidants. Thus, pretreatment with FA offers protection against gamma radiation induced inflammation. PMID:24854039

Das, Ujjal; Manna, Krishnendu; Sinha, Mahuya; Datta, Sanjukta; Das, Dipesh Kr; Chakraborty, Anindita; Ghosh, Mahua; Saha, Krishna Das; Dey, Sanjit

2014-01-01

394

The effect of probiotics for preventing radiation-induced morphological changes in intestinal mucosa of rats.  

PubMed

Radiation therapy is an important treatment modality for abdominal or pelvic cancer, but there is a common and serious complication such as radiation-induced enteritis. Probiotics is reported to have positive effects against radiation-induced enteropathy. In this study, morphological changes of bowel mucosa were analyzed in rats to presume the effect of probiotics on radiation-induced enteritis and its correlation with radiation dose. A total of 48 adult male Sprague-Dawley rats were randomly assigned to two groups and received a solution containing 1.0×10(8) colony-forming units of Lactiobacillus acidophilus or water once daily for 10 days. Each of two groups was divided into three subgroups and abdomino-pelvic area of each subgroup was irradiated with 10, 15, and 20 Gy, respectively on the seventh day of feeding the solutions. All rats were sacrificed 3 days after irradiation and the mucosal thickness and villus height of jejunum, ileum and colon were measured. The morphological parameters of the small intestine represented significant differences between two solution groups irradiated 10 or 15 Gy, except for villus height of jejunum in 15 Gy-subgroup (P=0.065). There was no significant morphometric difference between two groups irradiated with 20 Gy of radiation. Probiotics appear to be effective for the morphological shortening of small intestinal mucosa damaged by radiation less than or equal to 15 Gy. PMID:25368490

Ki, Yongkan; Kim, Wontaek; Cho, Heunglae; Ahn, Kijung; Choi, Youngmin; Kim, Dongwon

2014-10-01

395

Amelioration of radiation-induced hematopoietic and gastrointestinal damage by Ex-RAD® in mice  

PubMed Central

The aim of the present study was to assess recovery from hematopoietic and gastrointestinal damage by Ex-RAD®, also known as ON01210.Na (4-carboxystyryl-4-chlorobenzylsulfone, sodium salt), after total body radiation. In our previous study, we reported that Ex-RAD, a small-molecule radioprotectant, enhances survival of mice exposed to gamma radiation, and prevents radiation-induced apoptosis as measured by the inhibition of radiation-induced protein 53 (p53) expression in cultured cells. We have expanded this study to determine best effective dose, dose-reduction factor (DRF), hematological and gastrointestinal protection, and in vivo inhibition of p53 signaling. A total of 500 mg/kg of Ex-RAD administered at 24 h and 15 min before radiation resulted in a DRF of 1.16. Ex-RAD ameliorated radiation-induced hematopoietic damage as monitored by the accelerated recovery of peripheral blood cells, and protection of granulocyte macrophage colony-forming units (GM-CFU) in bone marrow. Western blot analysis on spleen indicated that Ex-RAD treatment inhibited p53 phosphorylation. Ex-RAD treatment reduces terminal deoxynucleotidyl transferase mediated dUTP nick end labeling assay (TUNEL)-positive cells in jejunum compared with vehicle-treated mice after radiation injury. Finally, Ex-RAD preserved intestinal crypt cells compared with the vehicle control at 13 and 14 Gy. The results demonstrated that Ex-RAD ameliorates radiation-induced peripheral blood cell depletion, promotes bone marrow recovery, reduces p53 signaling in spleen and protects intestine from radiation injury. PMID:22843617

Ghosh, Sanchita P.; Kulkarni, Shilpa; Perkins, Michael W.; Hieber, Kevin; Pessu, Roli L.; Gambles, Kristen; Maniar, Manoj; Kao, Tzu-Cheg; Seed, Thomas M.; Kumar, K. Sree

2012-01-01

396

Impact of p53 status on heavy-ion radiation-induced micronuclei in circulating erythrocytes  

NASA Technical Reports Server (NTRS)

Transgenic mice that differed in their p53 genetic status were exposed to an acute dose of highly charged and energetic (HZE) iron particle radiation. Micronuclei (MN) in two distinct populations of circulating peripheral blood erythrocytes, the immature reticulocytes (RETs) and the mature normochromatic erythrocytes (NCEs), were measured using a simple and efficient flow cytometric procedure. Our results show significant elevation in the frequency of micronucleated RETs (%MN-RETs) at 2 and 3 days post-radiation. At 3 days post-irradiation, the magnitude of the radiation-induced MN-RET was 2.3-fold higher in the irradiated p53 wild-type animals compared to the unirradiated controls, 2.5-fold higher in the p53 hemizygotes and 4.3-fold higher in the p53 nullizygotes. The persistence of this radiation-induced elevation of MN-RETs is dependent on the p53 genetic background of the animal. In the p53 wild-type and p53 hemizygotes, %MN-RETs returned to control levels by 9 days post-radiation. However, elevated levels of %MN-RETs in p53 nullizygous mice persisted beyond 56 days post-radiation. We also observed elevated MN-NCEs in the peripheral circulation after radiation, but the changes in radiation-induced levels of MN-NCEs appear dampened compared to those of the MN-RETs for all three strains of animals. These results suggest that the lack of p53 gene function may play a role in the iron particle radiation-induced genomic instability in stem cell populations in the hematopoietic system.

Chang, P. Y.; Torous, D.; Lutze-Mann, L.; Winegar, R.

2000-01-01

397

Heavy ion irradiation of crystalline water ice  

E-print Network

Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice sputtering yield. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice sputtering is measured on the infrared spectra, and the fitted sputtering-yield dependence, combined with previous measurements, is quadratic over three decades of electronic ...

Dartois, E; Boduch, P; Brunetto, R; Chabot, M; Domaracka, A; Ding, J J; Kamalou, O; Lv, X Y; Rothard, H; da Silveira, E F; Thomas, J C

2015-01-01

398

Radiation Induced Stress Relaxation in Silicone and Polyurethane Elastomers  

SciTech Connect

Many different materials are used in the National Ignition Facility, NIF, located at Lawrence Livermore National Laboratory, LLNL. Some of these are exposed to significant doses of ionizing radiation. Two elastomers are of special interest because they are used in sealing applications with long expected lifetimes. These are LPU4, a polyurethane formulated at LLNL, and Dow Corning DC93-500, a silicone RTV elastomer. In 2004 a program to determine the impact of ionizing radiation on the stress relaxation and compression set characteristics of these two elastomers was undertaken. Since the materials are used in continuous compression and must reliably seal, the primary test utilized was a stress relaxation test. This test provides insight into the ability of a seal to remain functional in a static seal. The test determines how much residual force remains after a certain period of time under compression. The temperature and absorbed radiation dose can dramatically impact this property. In this study the only independent environmental variable studied is the effect of radiation at ambient temperatures. Two levels of radiation exposure were studied, 1 MRad, and 10 MRad. One of the independent test parameters is the compression deflection during storage and in this test the value used was 25%. The need for a compression retention mechanism ruled out radiation exposure in the compressed direction since the high atomic number materials for that device would block the radiation. Therefore, an annular ring was chosen for the specimen shape. The procedures are, as closely as possible, based on ASTM D 6147-97. Since the data is readily obtained at the end of the stress relaxation test, the samples were also evaluated for compression set. Compression set is the essentially permanent deformation incurred in a seal after the seal is compressed for some period of time and then unloaded. Though this is indicative of potential sealing reliability, it is not as direct an indicator of seal performance as is stress relaxation. Compression set does not yield any useable, quantified information but is an indicator of viscoelastic deformation with time. The needed thickness measurements were obtained both from the unloading curves and direct measurement in general accordance with ASTM D395-03. The radiation source for this testing was the Co60 gamma source located at Lawrence Livermore National Laboratory (LLNL). This source has an exposure vessel approximately 29.2cm (11.5-inch) tall with an inside diameter of 7.44cm (2.93-inch). Because of the geometry limits, cylindrical symmetry and limited volume, a standard stress relaxation test such as ASTM D 6147-97 could not be utilized and a modified test was developed. An additional constraint imposed by the vertical asymmetry of the radiation dose in the exposure chamber was a limited height with reasonably uniform radiation exposure. The specific dimensions and radiation characteristics of the test cell are in Appendix A.

Spellman, G; Gourdin, W; Jensen, W; Pearson, M; Fine, I

2007-08-22

399

Solar ultraviolet radiation induced variations in the stratosphere and mesosphere  

NASA Technical Reports Server (NTRS)

The detectability and interpretation of short-term solar UV induced responses of middle atmospheric ozone, temperature, and dynamics are reviewed. The detectability of solar UV induced perturbations in the middle atmosphere is studied in terms of seasonal and endogenic dynamical variations. The interpretation of low-latitude ozone and possible temperature responses on the solar rotation time scale is examined. The use of these data to constrain or test photochemical model predictions is discussed.

Hood, L. L.

1987-01-01

400

Radiation-Induced Apoptosis Varies Among Individuals and is Modified by Sex and Age  

PubMed Central

Purpose Although there are considerable data on mechanisms of radiation-induced apoptosis in vitro and in animal models, little is known about functional variation in these pathways in humans. We sought to develop a tractable system to evaluate this. Materials and methods Peripheral blood mononuclear cells were isolated from 90 healthy volunteers, divided into two aliquots, one irradiated with a 5 Gy dose and the other sham-treated (0 Gy), and assessed for damage-induced apoptosis after 24 hours. To investigate reproducibility, ten individuals spanning the entire radiation-induced apoptotic range were tested three times each, with 3–6 months between replicates. Results We observed surprising heterogeneity in apoptosis among individuals, ranging from 21–62%. Biological replicates from a single individual, however, were completely concordant, suggesting the variability observed across individuals is not the result of stochastic or short-term effects. We found significantly higher radiation-induced apoptosis in males than in females (Mean: 41.0% vs. 30.7%; p < 3.5 × 10?7). Moreover, advancing age was associated with decreasing radiation-induced apoptosis in males (p = 0.01) but not females (p = 0.82).a Conclusions Our results provide evidence that the function of cellular pathways crucial for stress-induced apoptosis varies by sex and could decline with age in humans. PMID:24882388

Applebaum, Mark A.; Skol, Andrew D.; Bond, Elisabeth E.; Overholtzer, Michael; Bond, Gareth L.; Onel, Kenan

2014-01-01

401

COGNITIVE DEFICITS INDUCED BY 56FE RADIATION EXPOSURE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Exposing rats to particles of high energy and charge (e.g., 56Fe) disrupts neuronal systems and the behaviors mediated by them; these adverse behavioral and neuronal effects are similar to those seen in aged animals. Because cognition declines with age, and our previous study showed that radiation ...

402

Simulation of ion beam induced current in radiation detectors and microelectronic devices.  

SciTech Connect

Ionizing radiation is known to cause Single Event Effects (SEE) in a variety of electronic devices. The mechanism that leads to these SEEs is current induced by the radiation in these devices. While this phenomenon is detrimental in ICs, this is the basic mechanism behind the operation of semiconductor radiation detectors. To be able to predict SEEs in ICs and detector responses we need to be able to simulate the radiation induced current as the function of time. There are analytical models, which work for very simple detector configurations, but fail for anything more complex. On the other end, TCAD programs can simulate this process in microelectronic devices, but these TCAD codes costs hundreds of thousands of dollars and they require huge computing resources. In addition, in certain cases they fail to predict the correct behavior. A simulation model based on the Gunn theorem was developed and used with the COMSOL Multiphysics framework.

Vizkelethy, Gyorgy

2009-10-01

403

Sulforaphane mitigates genotoxicity induced by radiation and anticancer drugs in human lymphocytes.  

PubMed

Sulforaphane, present in cruciferous vegetables such as broccoli, is a dietary anticancer agent. Sulforaphane, added 2 or 20 h following phytohemaglutinin stimulation to cultured peripheral blood lymphocytes of individuals accidentally exposed to mixed ? and ?-radiation, reduced the micronucleus frequency by up to 70%. Studies with whole blood cultures obtained from healthy volunteers confirmed the ability of sulforaphane to ameliorate ?-radiation-induced genotoxicity and to reduce micronucleus induction by other DNA-damaging anticancer agents, such as bleomycin and doxorubicin. This reduction in genotoxicity in lymphocytes treated at the G(0) or G(1) stage suggests a role for sulforaphane in modulating DNA repair. Sulforaphane also countered the radiation-induced increase in lymphocyte HDAC activity, to control levels, when cells were treated 2 h after exposure, and enhanced histone H4 acetylation status. Sulforaphane post-irradiation treatment enhanced the CD 34(+)Lin(-) cell population in culture. Sulforaphane has therapeutic potential for management of the late effects of radiation. PMID:24004877

Katoch, Omika; Kumar, Arun; Adhikari, Jawahar S; Dwarakanath, Bilikere S; Agrawala, Paban K

2013-12-12

404

Inter-chromosomal heterogeneity in the formation of radiation induced chromosomal aberrations  

SciTech Connect

it is generally assumed that radiation induced chromosomal lesions are distributed randomly and repaired randomly among the genome. Recent studies using fluorescent in situ hybridization (FISH) and chromosome specific DNA libraries indicate that some chromosomes are more sensitive for radiation induced aberration formation than others. Chromosome No. 4 in human and chromosome No. 8 in Chinese hamster have been found to involve more in exchange aberrations than others, when calculated on the basis of their DNA content. Painting with arm specific chromosome libraries indicate that the frequencies of radiation induced intra-chromosome exchanges (i.e., between the arms of a chromosome, such as centric rings and inversions) are far in excess than one would expect on the basis of the frequencies of observed inter-chromosomal exchanges. The possible factors leading to the observed heterogeneity will be discussed.

Natarajan, A.T.; Vermeulen, S.; Boei, J.J.W.A. [Leiden Univ. (Netherlands)

1997-10-01

405

Non-Targeted Effects Induced by Ionizing Radiation: Mechanisms and Potential Impact on Radiation Induced Health Effects  

SciTech Connect

Not-targeted effects represent a paradigm shift from the "DNA centric" view that ionizing radiation only elicits biological effects and subsequent health consequences as a result of an energy deposition event in the cell nucleus. While this is likely true at higher radiation doses (> 1Gy), at low doses (< 100mGy) non-targeted effects associated with radiation exposure might play a significant role. Here definitions of non-targeted effects are presented, the potential mechanisms for the communication of signals and signaling networks from irradiated cells/tissues are proposed, and the various effects of this intra- and intercellular signaling are described. We conclude with speculation on how these observations might lead to and impact long-term human health outcomes.

Morgan, William F.; Sowa, Marianne B.

2015-01-01

406

The Radiation-Induced Formation of Excited States of Aromatic Hydrocarbons in Benzene and Cyclohexane. I. Radiation Induced Fluorescence from Solutions of Aromatic Hydrocarbons in Cyclohexane  

Microsoft Academic Search

The nature of radiation-induced fluorescence from solutions of anthracene, naphthalene and pyrene in cyclohexane has been investigated. Evidence is presented for the formation of excited singlet solute molecules via charge recombination processes. Rate constants, measured by the pulse radiolysis technique, are reported for the quenching of excited singlet state molecules of naphthalene and pyrene by oxygen, xenon, iodine, 1,3-cyclohexadiene, nitrous

E. L. Frankevich; T. Morrow; G. A. Salmon

1972-01-01

407

Chromosomal Damages and Mutagenesis in Mammalian and Human Cells Induced by Ionizing Radiation With Different LET  

Microsoft Academic Search

\\u000a On the basis of literature and proper data the inference was made about the essential role of structural chromosomal (and\\u000a gene) damages in spontaneous and radiation-induced mutagenesis of mammalian and human cells on HPRT-loci. The evidence of\\u000a the increasing role of these damages in the mutagenesis after the influence of ionizing radiation with high LET are considered.\\u000a The consequences of

R. D. Govorun

1997-01-01

408

Review of research on use of radiation-induced mutations in crop breeding in Japan  

Microsoft Academic Search

In Japan, the research on radiation-induced mutation has been conducted as one of the promising methods of plant breeding. Although in the beginning the principal methods used are X-rays and 32P, we now have various kinds of radiation facilities available for mutation breeding. The fundamental aspects of mutation breeding are investigated at several universities and institutes, and the practical breeding

Takane Matsuo; Hikoyuki Yamaguchi

1962-01-01

409

Medium-Induced Gluon Radiation off Massive Quarks Fills the Dead Cone  

Microsoft Academic Search

We calculate the transverse momentum dependence of the medium-induced gluon energy distribution radiated off massive quarks in spatially extended QCD matter. In the absence of a medium, the distribution shows a characteristic mass-dependent depletion of the gluon radiation for angles smaller than m\\/E, the so-called dead cone effect. Medium-modifications of this spectrum are calculated as a function of quark mass,

Nestor Armesto-Pérez; Carlos A. Salgado; Urs Achim Wiedemann

2004-01-01

410

Confocal Imaging of Thermal Lensing Induced by Near-IR Laser Radiation in an Artificial Eye  

Microsoft Academic Search

A custom confocal imaging system was built and used to record a probe beam's spatiotemporal response to a thermal lens induced by a near-IR laser radiation source in a water-filled artificial eye. The IR laser radiation input power levels were varied between 150 and 890 mW at wavelengths of 1110, 1130, 1150 and 1318 nm in order to determine the

Rebecca L. Vincelette; Jeffrey W. Oliver; Benjamin A. Rockwell; Robert J. Thomas; Ashley J. Welch

2010-01-01

411

Radiation Retinopathy Caused by Low Dose Irradiation and Antithyroid Drug-Induced Systemic Vasculitis  

Microsoft Academic Search

Background: We report on a patient with Graves’ disease with radiation retinopathy caused by lowdose irradiation and antithyroid drug-induced antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis. Case: A 38-year-old woman with Graves’ disease presented with bilateral blurred vision, microaneurysms, telangiectasia, and macular edema. The patient was examined by ophthalmoscopy and fluorescein angiography, and radiation retinopathy was diagnosed. Observations: The patient had been

Koh-Hei Sonoda; Masahiro Yamamoto; Tatsuro Ishibashi

2005-01-01

412

Clinical features of radiation-induced carotid atherosclerosis.  

PubMed

Carotid arteries frequently receive significant incidental doses of radiation during the treatment of malignant diseases, including head and neck cancer, breast cancer and lymphoma. Vascular injury after treatment may result in carotid artery stenosis and increased risk of neurological sequelae, such as stroke and transient ischaemic attack. The long latent interval from treatment to the development of clinical complications makes investigation of this process difficult, particularly in regard to the design of interventional clinical studies. Nevertheless, there is compelling clinical evidence that radiation contributes to carotid atherosclerosis. This overview examines the effect of radiotherapy on the carotid arteries, the underlying pathological processes and their clinical manifestations. The use of serum biomarkers in risk-prediction models and the potential value of new imaging techniques as tools for defining earlier surrogate end points will also be discussed. PMID:24188597

Gujral, D M; Shah, B N; Chahal, N S; Senior, R; Harrington, K J; Nutting, C M

2014-02-01

413

Radiation induces genomic instability and mammary ductal dysplasia in Atm heterozygous mice  

NASA Technical Reports Server (NTRS)

Ataxia-telangiectasia (AT) is a genetic syndrome resulting from the inheritance of two defective copies of the ATM gene that includes among its stigmata radiosensitivity and cancer susceptibility. Epidemiological studies have demonstrated that although women with a single defective copy of ATM (AT heterozygotes) appear clinically normal, they may never the less have an increased relative risk of developing breast cancer. Whether they are at increased risk for