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Sample records for affect radiation sensitivity

  1. Radiation sensitizers

    International Nuclear Information System (INIS)

    The following classes of radiosensitizers are discussed: electron affinic compounds, pyrimidine analogs, and antibiotics. Metronidazole and nitroimidazole are discussed as examples of electron-affinic compounds. Studies on the enhancement ratio for sensitization of x-irradiated hamster cells showed that these drugs sensitize at concentrations much lower than the toxic concentrations. Criteria for a clinically useful hypoxic cell sensitizer are listed and mechanisms of electron-affinic sensitizers are discussed. The radiosensitizing effects of the pyrimidine analogs, BUDR, BCDR, IUDR, CUDR, and FUDR, are examined and the enhancement of radiation effects by the chemotherapeutic agent, 5-fluorouracil, is discussed. Other agents discussed are methotrexate, actinomycin D, bleomycin, and adriamycin

  2. Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Ann-Sofie, E-mail: ann-sofie.gustafsson@bms.uu.se; Abramenkovs, Andris; Stenerlöw, Bo

    2014-11-15

    Highlights: • We reduced the level of DNA-PKcs with siRNA and examined cells after γ-irradiation. • Low DNA-PKcs levels lead to radiosensitivity but did not affect repair of DSB. • Low DNA-PKcs levels may block progression of mitosis. • DNA-PKcs role in mitotic progression is independent of its role in DSB repair. • We suggest different mechanisms by which loss of DNA-PKcs function sensitize cells. - Abstract: Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80–95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure

  3. Caffeic acid phenethyl ester preferentially sensitizes CT26 colorectal adenocarcinoma to ionizing radiation without affecting bone marrow radioresponse

    International Nuclear Information System (INIS)

    Purpose: Caffeic acid phenethyl ester (CAPE), a component of propolis, was reported capable of depleting glutathione (GSH). We subsequently examined the radiosensitizing effect of CAPE and its toxicity. Methods and Materials: The effects of CAPE on GSH level, GSH metabolism enzyme activities, NF-κB activity, and radiosensitivity in mouse CT26 colorectal adenocarcinoma cells were determined. BALB/c mouse with CT26 cells implantation was used as a syngeneic in vivo model for evaluation of treatment and toxicity end points. Results: CAPE entered CT26 cells rapidly and depleted intracellular GSH in CT26 cells, but not in bone marrow cells. Pretreatment with nontoxic doses of CAPE significantly enhanced cell killing by ionizing radiation (IR) with sensitizer enhancement ratios up to 2.2. Pretreatment of CT26 cells with N-acetyl-L-cysteine reversed the GSH depletion activity and partially blocked the radiosensitizing effect of CAPE. CAPE treatment in CT26 cells increased glutathione peroxidase, decreased glutathione reductase, and did not affect glutathione S-transferase or γ-glutamyl transpeptidase activity. Radiation activated NF-κB was reversed by CAPE pretreatment. In vivo study revealed that pretreatment with CAPE before IR resulted in greater inhibition of tumor growth and prolongation of survival in comparison with IR alone. Pretreatment with CAPE neither affected body weights nor produced hepatic, renal, or hematopoietic toxicity. Conclusions: CAPE sensitizes CT26 colorectal adenocarcinoma to IR, which may be via depleting GSH and inhibiting NF-κB activity, without toxicity to bone marrow, liver, and kidney

  4. Radiation sensitive acrylate composition

    International Nuclear Information System (INIS)

    This application relates to radiation-sensitive compositions and more particularly to such compositions comprising acrylated esters. As used in this specification, the term acrylated esters refers to either acrylic or methacrylic acid resins. 3 tabs

  5. X-ray survival characteristics and genetic analysis for nineSaccharomyces deletion mutants that affect radiation sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Game, John C.; Williamson, Marsha S.; Baccari, Clelia

    2006-07-21

    We examine ionizing radiation (IR) sensitivity and epistasisrelationships of several Saccharomyces mutants affectingpost-translational modifications of histones H2B and H3. Mutantsbre1delta, lge1delta, and rtf1delta, defective in histone H2B lysine 123ubiquitination, show IR sensitivity equivalent to that of the dot1deltamutant that we reported on earlier, consistent with published findingsthat Dot1p requires H2B K123 ubiquitination to fully methylate histone H3K79. This implicates progressive K79 methylation rather thanmono-methylation in IR resistance. The set2delta mutant, defective in H3K36 methylation, shows mild IR sensitivity whereas mutants that abolishH3 K4 methylation resemble wild type. The dot1delta, bre1delta, andlge1delta mutants show epistasis for IR sensitivity. The paf1deltamutant, also reportedly defective in H2B K123 ubiquitination, confers nosensitivity. The rad6delta, rad51null, rad50delta, and rad9deltamutations are epistatic to bre1? and dot1delta, but rad18delta andrad5delta show additivity with bre1delta, dot1delta, and each other. Thebre1delta rad18delta double mutant resembles rad6delta in sensitivity;thus the role of Rad6p in ubiquitinating H2B accounts for its extrasensitivity compared to rad18delta. We conclude that IR resistanceconferred by BRE1 and DOT1 is mediated through homologous recombinationalrepair, not postreplication repair, and confirm findings of a G1checkpoint role for the RAD6/BRE1/DOT1 pathway.

  6. [Genome sensitivity and genotoxic effects features in children-teenagers affected by radon radiation in living and educational environment].

    Science.gov (United States)

    Druzhinin, V G; Akhmat'ianova, V R; Golovina, T A; Volkov, A N; Minina, V I; Larionov, A V; Makeeva, E A

    2009-01-01

    The results of chromosomal aberration level and spectrum study in 48-hours peripheral blood lymphocytes cultures of 10-19 years old children-teenagers (n = 132, mean 14.2 +/- 0.16 years old) living in the south part of Kemerovskaya area Gornaya Shoria are presented. Mean metaphases with aberrations were 4.74 +/- 0.21% in studied group that is significantly higher (p polycentric, ring chromosomes and multiple pair dot fragments. The reasons of chromosomal aberrations frequency increasing in this mountain area inhabitants are discussed (ultrahigh radon radiation doses influence are included). PMID:19947520

  7. Factors Affecting Aerosol Radiative Forcing

    Science.gov (United States)

    Wang, Jingxu; Lin, Jintai; Ni, Ruijing

    2016-04-01

    Rapid industrial and economic growth has meant a large amount of aerosols in the atmosphere with strong radiative forcing (RF) upon the climate system. Over parts of the globe, the negative forcing of aerosols has overcompensated for the positive forcing of greenhouse gases. Aerosol RF is determined by emissions and various chemical-transport-radiative processes in the atmosphere, a multi-factor problem whose individual contributors have not been well quantified. In this study, we analyze the major factors affecting RF of secondary inorganic aerosols (SIOAs, including sulfate, nitrate and ammonium), primary organic aerosol (POA), and black carbon (BC). We analyze the RF of aerosols produced by 11 major regions across the globe, including but not limited to East Asia, Southeast Asia, South Asia, North America, and Western Europe. Factors analyzed include population size, per capita gross domestic production (GDP), emission intensity (i.e., emissions per unit GDP), chemical efficiency (i.e., mass per unit emissions) and radiative efficiency (i.e., RF per unit mass). We find that among the 11 regions, East Asia produces the largest emissions and aerosol RF, due to relatively high emission intensity and a tremendous population size. South Asia produce the second largest RF of SIOA and BC and the highest RF of POA, in part due to its highest chemical efficiency among all regions. Although Southeast Asia also has large emissions, its aerosol RF is alleviated by its lowest chemical efficiency. The chemical efficiency and radiative efficiency of BC produced by the Middle East-North Africa are the highest across the regions, whereas its RF is lowered by a small per capita GDP. Both North America and Western Europe have low emission intensity, compensating for the effects on RF of large population sizes and per capita GDP. There has been a momentum to transfer industries to Southeast Asia and South Asia, and such transition is expected to continue in the coming years. The

  8. Albendazole sensitizes cancer cells to ionizing radiation

    International Nuclear Information System (INIS)

    Brain metastases afflict approximately half of patients with metastatic melanoma (MM) and small cell lung cancer (SCLC) and represent the direct cause of death in 60 to 70% of those affected. Standard of care remains ineffective in both types of cancer with the challenge of overcoming the blood brain barrier (BBB) exacerbating the clinical problem. Our purpose is to determine and characterize the potential of albendazole (ABZ) as a cytotoxic and radiosensitizing agent against MM and SCLC cells. Here, ABZ's mechanism of action as a DNA damaging and microtubule disrupting agent is assessed through analysis of histone H2AX phosphorylation and cell cyle progression. The cytotoxicity of ABZ alone and in combination with radiation therapy is determined though clonogenic cell survival assays in a panel of MM and SCLC cell lines. We further establish ABZ's ability to act synergistically as a radio-sensitizer through combination index calculations and apoptotic measurements of poly (ADP-ribose) polymerase (PARP) cleavage. ABZ induces DNA damage as measured by increased H2AX phosphorylation. ABZ inhibits the growth of MM and SCLC at clinically achievable plasma concentrations. At these concentrations, ABZ arrests MM and SCLC cells in the G2/M phase of the cell cycle after 12 hours of treatment. Exploiting the notion that cells in the G2/M phase are the most sensitive to radiation therapy, we show that treatment of MM and SCLC cells treated with ABZ renders them more sensitive to radiation in a synergistic fashion. Additionally, MM and SCLC cells co-treated with ABZ and radiation exhibit increased apoptosis at 72 hours. Our study suggests that the orally available antihelminthic ABZ acts as a potent radiosensitizer in MM and SCLC cell lines. Further evaluation of ABZ in combination with radiation as a potential treatment for MM and SCLC brain metastases is warranted

  9. Radiation sensitive polymer gel dosimeters

    International Nuclear Information System (INIS)

    Full text: Radiation sensitive gels are studied for their potential to retain a permanent 3D dose distribution for applications in radiotherapy. Co-monomers dissolved in a tissue-equivalent hydrogel undergo a polymerization reaction upon absorption of ionizing radiation. The polymer formed influences the local spin-spin relaxation time (T2) of the dosimeter that can be determined using magnetic resonance imaging (MRI). The relationship between T2 and the absorbed dose was studied for different initial chemical compositions. The aim was to find a model linking the changes in T2 with absorbed dose to the initial composition of the dosimeter. It is believed this will help designing new gel dosimeters having desired properties to minimize the uncertainty in the determination of the dose distribution. 1H, 13C nuclear magnetic resonance spectroscopy and FT-Raman spectroscopy were used to quantify the amount of monomers still remaining after the absorption of a given dose of radiation. This data is used to model the changes of T2 as a function of the absorbed dose. A model of fast exchange of magnetization between three proton pools was used, where the fraction of protons (fxH ) in the xth pool is obtained from the chemical composition of the dosimeter and the apparent T2 of each pool is determined for a given composition. Initially, the protons are contained in two pools; a mobile (mob), which contains the water protons and the monomers protons, and a gelatin (gela) proton pool. The mobile pool is partially depleted as polymer is formed, the protons are transferred into the polymer (pol) pool. In the figure, the experimental data along with the calculated values are plotted for three different monomer concentrations, with the gelatin concentration fixed. The model is seen to provide a good fit to the experimental data

  10. Electromagnetic Radiation can affect the Lift Force

    OpenAIRE

    De Aquino, Fran

    2015-01-01

    Here we show that, under certain circumstances, electromagnetic radiations can strongly reduce the lift force. An aircraft for example, can be shot down when reached by a flux of specific electromagnetic radiation. This discovery can help the aircraft pilots to avoid regions where there are electromagnetic radiations potentially dangerous. Not only the flight of the aircrafts are affected by the electromagnetic radiation, but also the flight of any flying object whose flight depends on the li...

  11. Relationship of cataract to radiation sensitivity

    International Nuclear Information System (INIS)

    This investigation was conducted to ascertain whether cellular hypersensitivity to radiation may be identified as a possible cause of cataract in persons exposed to low levels of radiation. Patients were studied in whom posterior subcapsular cataract (PSC) had followed probable exposure to low levels of radiation or in whom PSC had developed before the age of 60 without known exposure. Patients with cataract were compared with age and sex matched controls. Radiation sensitivity was estimated by measuring clonal growth of skin fibroblasts and peripheral blood lymphocytes after exposure to graded doses of radiation and by measuring postirradiation reconstruction of separated nuclear material from lymphocytes. Results show variations in radiation sensitivity between patients, without significant differences from the controls. It is concluded that radiation hypersensitivity is not normally associated with development of posterior subcapsular cataract. (author)

  12. WORTMANNIN affect cellular response by radiation

    International Nuclear Information System (INIS)

    Objective: To observe radiation Response of cells by WORTMANNIN (WT), which is inhibitor for Phosphatidylinositol-3 Kinase (PI-3K). Methods: LP3 cells are prepared with different concentration of WT for 1 hour and receive different dose γ irradiation. To continue the cell for clone culture, and get the production of dose-survival curve. 1800 pulsed-field gel electrophoresis is used to detect DNA double-strand breaks after the 20 Gy γ irradiation. Continue to use the mobility shift assays (Electrophoresis Mobility Shift Assay, EMSA) to observe NF-kB transcription factor of the corresponding changes. Result: WT can be found to increase the radiation sensitivity of SP3 cells, the best sensitizer concentration in 20 μmol /L or more, obvious sensitizing effect within 6 h time; the electrophoresis experiments showed that after irradiation with time, by 50 μmol /L WT group DNA the gel is higher than that of the simple exposure group; transcription factor NF-kB binding activity in the 6 hours after exposure experiences a low-rise and then the process of rising with its the peak of the change reaching after about 3 hours after irradiation. Conclusion: It suggests the existence of PI-3K-mediated radiation sensitizer pathways. Ionizing radiation may activate NF-kB, which caused some DNA damage repair and other defense mechanisms and cell-related gene activity in order to reduce radiation damage. WT may block this process through the early stages of radiation-sensitizing effect. (authors)

  13. Effect of troglitazone on radiation sensitivity in cervix cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    An, Zheng Zhe; Liu, Xian Guang; Song, Hye Jin; Choi, Chi Hwan; Kim, Won Dong; Park, Woo Yoon [Chungbuk National University College of Medicine, Cheongju (Korea, Republic of); Yu, Jae Ran [Konkuk University College of Medicine, Chungju (Korea, Republic of)

    2012-06-15

    Troglitazone (TRO) is a peroxisome proliferator-activated receptor {gamma} (PPAR{gamma} ) agonist. TRO has antiproliferative activity on many kinds of cancer cells via G1 arrest. TRO also increases Cu{sup 2+}/Zn{sup 2+} -superoxide dismutase (CuZnSOD) and catalase. Cell cycle, and SOD and catalase may affect on radiation sensitivity. We investigated the effect of TRO on radiation sensitivity in cancer cells in vitro. Three human cervix cancer cell lines (HeLa, Me180, and SiHa) were used. The protein expressions of SOD and catalase, and catalase activities were measured at 2-10 {mu}M of TRO for 24 hours. Cell cycle was evaluated with flow cytometry. Reactive oxygen species (ROS) was measured using 2',7'-dichlorofluorescin diacetate. Cell survival by radiation was measured with clonogenic assay. By 5 {mu}M TRO for 24 hours, the mRNA, protein expression and activity of catalase were increased in all three cell lines. G0- G1 phase cells were increased in HeLa and Me180 by 5 {mu}M TRO for 24 hours, but those were not increased in SiHa. By pretreatment with 5 {mu}M TRO radiation sensitivity was increased in HeLa and Me180, but it was decreased in SiHa. In Me180, with 2 {mu}M TRO which increased catalase but not increased G0-G1 cells, radiosensitization was not observed. ROS produced by radiation was decreased with TRO. TRO increases radiation sensitivity through G0-G1 arrest or decreases radiation sensitivity through catalasemediated ROS scavenging according to TRO dose or cell types. The change of radiation sensitivity by combined with TRO is not dependent on the PPAR {gamma} expression level.

  14. Parental Sensitivity, Infant Affect, and Affect Regulation: Predictors of Later Attachment.

    Science.gov (United States)

    Braungart-Rieker, Julia M.; Garwood, Molly M.; Powers, Bruce P.; Wang, Xiaoyu

    2001-01-01

    Examined extent to which parent sensitivity, infant affect, and affect regulation at 4 months predicted mother- and father-infant attachment classifications at 1 year. Found that affect regulation and maternal sensitivity discriminated infant-mother attachment groups. The association between maternal sensitivity and infant-mother attachment was…

  15. Aspects of dosimetry using radiation sensitive gels

    International Nuclear Information System (INIS)

    The use of radiation sensitive gels for dosimetry measurements was first suggested in the 1950s. It was subsequently shown that radiation induced changes in nuclear magnetic resonance (NMR) relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured. However, due to predominantly diffusion-related limitations, alternative polymer gel dosimeters were suggested. Clinical applications of these radiologically tissue equivalent gel dosimeters using magnetic resonance imaging (MRI) have subsequently been reported in the literature. In Fricke gels, Fe2+ ions in ferrous sulphate solutions are usually dispersed throughout a gelatin or agarose hydrogel matrix. Radiation-induced changes in the dosimeters are considered to be either through direct absorption of ionising radiation or via intermediate water free radicals. Fe2+ ions are converted to Fe3+ ions with a corresponding change in paramagnetic properties that may be quantified using NMR relaxation measurements. In polymer gels, monomers are also dispersed in a gelatin or agarose hydrogel matrix. Monomers undergo a polymerisation reaction as a function of absorbed dose resulting in a three-dimensional polymer gel matrix. The radiation-induced formation of polymer influences NMR relaxation properties. The growth in polymer also results in other physical changes that may be used to quantify absorbed radiation dose. This thesis investigates various aspects of radiation dosimetry using radiation sensitive gels. Image processing software was developed to calculate NMR relaxation images of dosimetry gels. Measurements were undertaken to investigate the diffusion problem in Fricke gels. Radiological properties were theoretically modelled for both Fricke and polymer gels. A methodology was developed for the preparation of polymer gels. Vibrational spectroscopic studies were undertaken to investigate the underlying mechanism involved in the radiation-induced formation of polymer. MRI pulse

  16. Unique proteomic signature for radiation sensitive patients; a comparative study between normo-sensitive and radiation sensitive breast cancer patients

    Energy Technology Data Exchange (ETDEWEB)

    Skiöld, Sara [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden); Azimzadeh, Omid [Institute of Radiation Biology, German Research Center for Environmental Health, Helmholtz Zentrum München (Germany); Merl-Pham, Juliane [Research Unit Protein Science, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg (Germany); Naslund, Ingemar; Wersall, Peter; Lidbrink, Elisabet [Division of Radiotherapy, Radiumhemmet, Karolinska University Hospital, Stockholm (Sweden); Tapio, Soile [Institute of Radiation Biology, German Research Center for Environmental Health, Helmholtz Zentrum München (Germany); Harms-Ringdahl, Mats [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden); Haghdoost, Siamak, E-mail: Siamak.Haghdoost@su.se [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden)

    2015-06-15

    Highlights: • The unique protein expression profiles were found that separate radiosensitive from normal sensitive breast cancer patients. • The oxidative stress response, coagulation properties and acute phase response suggested to be the hallmarks of radiation sensitivity. - Abstract: Radiation therapy is a cornerstone of modern cancer treatment. Understanding the mechanisms behind normal tissue sensitivity is essential in order to minimize adverse side effects and yet to prevent local cancer reoccurrence. The aim of this study was to identify biomarkers of radiation sensitivity to enable personalized cancer treatment. To investigate the mechanisms behind radiation sensitivity a pilot study was made where eight radiation-sensitive and nine normo-sensitive patients were selected from a cohort of 2914 breast cancer patients, based on acute tissue reactions after radiation therapy. Whole blood was sampled and irradiated in vitro with 0, 1, or 150 mGy followed by 3 h incubation at 37 °C. The leukocytes of the two groups were isolated, pooled and protein expression profiles were investigated using isotope-coded protein labeling method (ICPL). First, leukocytes from the in vitro irradiated whole blood from normo-sensitive and extremely sensitive patients were compared to the non-irradiated controls. To validate this first study a second ICPL analysis comparing only the non-irradiated samples was conducted. Both approaches showed unique proteomic signatures separating the two groups at the basal level and after doses of 1 and 150 mGy. Pathway analyses of both proteomic approaches suggest that oxidative stress response, coagulation properties and acute phase response are hallmarks of radiation sensitivity supporting our previous study on oxidative stress response. This investigation provides unique characteristics of radiation sensitivity essential for individualized radiation therapy.

  17. Unique proteomic signature for radiation sensitive patients; a comparative study between normo-sensitive and radiation sensitive breast cancer patients

    International Nuclear Information System (INIS)

    Highlights: • The unique protein expression profiles were found that separate radiosensitive from normal sensitive breast cancer patients. • The oxidative stress response, coagulation properties and acute phase response suggested to be the hallmarks of radiation sensitivity. - Abstract: Radiation therapy is a cornerstone of modern cancer treatment. Understanding the mechanisms behind normal tissue sensitivity is essential in order to minimize adverse side effects and yet to prevent local cancer reoccurrence. The aim of this study was to identify biomarkers of radiation sensitivity to enable personalized cancer treatment. To investigate the mechanisms behind radiation sensitivity a pilot study was made where eight radiation-sensitive and nine normo-sensitive patients were selected from a cohort of 2914 breast cancer patients, based on acute tissue reactions after radiation therapy. Whole blood was sampled and irradiated in vitro with 0, 1, or 150 mGy followed by 3 h incubation at 37 °C. The leukocytes of the two groups were isolated, pooled and protein expression profiles were investigated using isotope-coded protein labeling method (ICPL). First, leukocytes from the in vitro irradiated whole blood from normo-sensitive and extremely sensitive patients were compared to the non-irradiated controls. To validate this first study a second ICPL analysis comparing only the non-irradiated samples was conducted. Both approaches showed unique proteomic signatures separating the two groups at the basal level and after doses of 1 and 150 mGy. Pathway analyses of both proteomic approaches suggest that oxidative stress response, coagulation properties and acute phase response are hallmarks of radiation sensitivity supporting our previous study on oxidative stress response. This investigation provides unique characteristics of radiation sensitivity essential for individualized radiation therapy

  18. Minocycline affects cocaine sensitization in mice

    OpenAIRE

    Chen, Hu; Uz, Tolga; Manev, Hari

    2009-01-01

    Growing evidence has pointed to an interaction between the tetracycline antibiotic minocycline and drugs with abuse liability such as opioids and amphetamines. In this work, we tested the hypothesis that similar to its effects on methamphetamine-induced locomotor sensitization, minocycline may influence the behavioral effects of cocaine. Experiments were performed in male C57BL/6J mice using an automated system to measure locomotor activity. We found that 80 mg/kg minocycline significantly re...

  19. Radiation-induced grafting of sensitive polymers

    International Nuclear Information System (INIS)

    Films of PP and PTFE were modified by gamma-radiation grafting of pH and thermo sensitive monomers (two step method) by using both the preirradiation and the direct methods. The effects of the absorbed dose, monomer concentration and reaction time were investigated. The surface chemistry of grafted samples was analyzed by FTIR-ATR spectroscopy, while their thermal properties were analyzed by TGA and DSC. The stimuli-responsive behavior was studied by swelling and contact angle in water, as well as by DSC. Sensitive films presented a critical pH and LCST. (author)

  20. Individual radiation sensitivity: implications in medical practice

    International Nuclear Information System (INIS)

    Important advances in radiotherapy and nuclear medicine towards better treatment modalities and safer applications have taken place in recent years. Progress in medical imaging, better tumour targeting and optimization of radiation delivery have allowed for dose escalation and improved patient outcome. However, the tolerance of normal tissues constitutes the limiting factor for dose escalation in therapeutical uses of ionizing radiation (IR). Patients vary considerably in their normal tissue response to IR even after similar treatments. As many as 5% of cancer patients develop severe effects to external radiation therapy in normal tissues within the treatment field: they may include acute effects such as erythema and desquamation of the exposed skin and mucosa that appear during or directly after radiotherapy, late effects developed months or years later, such as fibrosis and telangiectasia and cancer induction. Several patient and treatment related factors are known to influence the variability of side effects, however up to a 70% of the total variance of normal tissue radiation response remained unexplained. Thus, individual sensitivity to IR, i.e. hypersensitivity to carcinogenic risks (stochastic effects) and hypersensitivity to deterministic effects, is becoming an important issue in oncology and raises questions regarding the underlying mechanisms. The mechanisms of DNA repair, the signalling pathways involved in radiation sensitivity and non-targeted effects are key aspects, essential to understanding radiation effects at genetic level. Moreover, human genetic diseases that combine higher incidence of cancer and hypersensitivity to IR are associated with defects in cell response to DNA damage. Therefore, much interest has raised during the last years in the developing of predictive tests capable to detect in advance such hypersensitive conditions. The goal of this presentation is to review the possible mechanisms involved in genetic and epigenetic

  1. Individual radiation sensitivity: implications in medical practice

    Energy Technology Data Exchange (ETDEWEB)

    Gisone, P.; Dubner, D.; Perez, M.D.R.; Michelin, S.; Di Giogio, M. [Autoridad Regulatoria Nuclear, Buenos Aires (Argentina); Bourguignon, M. [Direction Generale de la Surete Nucleaire et de la Radioprotection, Paris (France)

    2006-07-01

    Important advances in radiotherapy and nuclear medicine towards better treatment modalities and safer applications have taken place in recent years. Progress in medical imaging, better tumour targeting and optimization of radiation delivery have allowed for dose escalation and improved patient outcome. However, the tolerance of normal tissues constitutes the limiting factor for dose escalation in therapeutical uses of ionizing radiation (IR). Patients vary considerably in their normal tissue response to IR even after similar treatments. As many as 5% of cancer patients develop severe effects to external radiation therapy in normal tissues within the treatment field: they may include acute effects such as erythema and desquamation of the exposed skin and mucosa that appear during or directly after radiotherapy, late effects developed months or years later, such as fibrosis and telangiectasia and cancer induction. Several patient and treatment related factors are known to influence the variability of side effects, however up to a 70% of the total variance of normal tissue radiation response remained unexplained. Thus, individual sensitivity to IR, i.e. hypersensitivity to carcinogenic risks (stochastic effects) and hypersensitivity to deterministic effects, is becoming an important issue in oncology and raises questions regarding the underlying mechanisms. The mechanisms of DNA repair, the signalling pathways involved in radiation sensitivity and non-targeted effects are key aspects, essential to understanding radiation effects at genetic level. Moreover, human genetic diseases that combine higher incidence of cancer and hypersensitivity to IR are associated with defects in cell response to DNA damage. Therefore, much interest has raised during the last years in the developing of predictive tests capable to detect in advance such hypersensitive conditions. The goal of this presentation is to review the possible mechanisms involved in genetic and epigenetic

  2. Radiation curable pressure sensitive adhesive composition

    International Nuclear Information System (INIS)

    Radiation curable pressure sensitive adhesive composition comprises: a polyoxyalkylene homo- or copolymer which is either a polyoxyethylene homopolymer or a poly (oxyethylene-oxypropylene) copolymer, or mixture thereof, having a molecular weight of from 1,700 to 90,000, in which at least 40 percent by weight of the oxyalkylene units are oxyethylene units; a liquid carbamyloxy alkyl acrylate; and, optionally, a photoinitiator

  3. FEU-49 photomultiplier sensitivity to Cherenkov radiation

    International Nuclear Information System (INIS)

    With the aim of verifying the possibility of applying the FEU-19 photomultiplier in large installations for recording the Cherenkov radiation in water, the quantum sensitivity of four specimens of FEU-49 has been measured. The measurements are carried out at a maximum thickness of a distilled water layer equal to 4 cm. The Cherenkov radiation has been produced in water by cosmic muons. Presented are flowsheets used for measuring quantum efficiency of the FEU-49 photocathode and dispersion of its amplification coefficient. By comparing the results of measurements performed with the calculated estimates, a conclusion has been drawn on their good agreements and on suitability of FEU-49 for recording the Cherenkov radiation in water

  4. In vivo radiation sensitivity of glioblastoma multiforme

    International Nuclear Information System (INIS)

    Purpose: Human glioblastoma (GBM) is one of the most resistant tumors to radiation. In previous reports, we have demonstrated a wide range of radiation sensitivity of GBM in vitro; that is, SF2 values of 0.2 to 0.8. The great sensitivity of some of the cell lines is not in accord with the almost invariably fatal clinical outcome of patients with GBM. The sensitivity of cells in vitro pertains to cells cultured in optimal nutritional conditions. The TCD50 (the radiation dose necessary to control 50% of the tumors locally) determined in lab animals is analogous to the use of radiation with curative intent in clinical radiation oncology. The aim of the present study was (a) to evaluate the sensitivity of GBM in vivo relative to that of other tumor types and (b) assess the relationship between the single dose TCD50 of the xenografts and the sensitivity of the corresponding cell lines in vitro. Methods and Materials: The TCD50 assay was used to study twelve human tumor lines. Four previously published values were added. A total of 10 GBM, 4 squamous cell carcinoma (SCC), 1 soft tissue sarcoma (STS), and 1 cancer colon (CC) are included in the analysis. For further suppression of the residual immune system, all the animals received 6 Gy whole-body irradiation 1 day before transplantation. Local tumor irradiations were given as a single dose, under conditions of clamp hypoxia using a Cs irradiator. Results: The TCD50 values for the 10 GBM xenografts varied between 32.5 and 75.2 Gy, with an average of 47.2 ± 13.1 Gy. The TCD50 values for the SCC were similar to those of the GBM and ranged from 40.7 and 54.4 Gy, with a mean of 46.8 ± 6.4. The difference between the average TCD50 of GBM and SCC was not significant. The STS and CC xenografts had TCD50 values of 46.0 and 49.2 Gy, respectively. No correlation was found between the TCD50 in vivo and the SF2 or D0 in vitro. Conclusions: Our data on GBM xenografts showed a wide range of sensitivities to single dose irradiation

  5. Radiation sensitivity of different citric pectins

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

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

  6. Radiation sensitivity of different citric pectins

    International Nuclear Information System (INIS)

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

  7. Radiation sensitive area detection device and method

    Science.gov (United States)

    Carter, Daniel C. (Inventor); Hecht, Diana L. (Inventor); Witherow, William K. (Inventor)

    1991-01-01

    A radiation sensitive area detection device for use in conjunction with an X ray, ultraviolet or other radiation source is provided which comprises a phosphor containing film which releases a stored diffraction pattern image in response to incoming light or other electromagnetic wave. A light source such as a helium-neon laser, an optical fiber capable of directing light from the laser source onto the phosphor film and also capable of channelling the fluoresced light from the phosphor film to an integrating sphere which directs the light to a signal processing means including a light receiving means such as a photomultiplier tube. The signal processing means allows translation of the fluoresced light in order to detect the original pattern caused by the diffraction of the radiation by the original sample. The optical fiber is retained directly in front of the phosphor screen by a thin metal holder which moves up and down across the phosphor screen and which features a replaceable pinhole which allows easy adjustment of the resolution of the light projected onto the phosphor film. The device produces near real time images with high spatial resolution and without the distortion that accompanies prior art devices employing photomultiplier tubes. A method is also provided for carrying out radiation area detection using the device of the invention.

  8. High sensitive radiation detector for radiology dosimetry

    International Nuclear Information System (INIS)

    Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, dose rate recorded and incident direction independence as well as linear dose response. This work presents the development and characterization of a novel Fricke gel system, based on modified chemical compositions making possible its application in clinical radiology. Properties of standard Fricke gel dosimeter for high dose levels are used as starting point and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose dependency, actually showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain a good enough dosimeter response for low dose levels. A suitable composition among those studied is selected as a good candidate for low dose level radiation dosimetry consisting on a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, xylenol orange and ultra-pure reactive grade water. Dosimeter samples are prepared in standard vials for its in phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated by typical kV X-ray tubes and calibrated Farmer type ionization chamber is used as reference to measure dose rates inside phantoms in at vials locations. Once sensitive material composition is already optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. According to

  9. High sensitive radiation detector for radiology dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Valente, M.; Malano, F. [Instituto de Fisica Enrique Gaviola, Oficina 102 FaMAF - UNC, Av. Luis Medina Allende, Ciudad Universitaria, 5000 Cordoba (Argentina); Molina, W.; Vedelago, J., E-mail: valente@famac.unc.edu.ar [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2014-08-15

    Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, dose rate recorded and incident direction independence as well as linear dose response. This work presents the development and characterization of a novel Fricke gel system, based on modified chemical compositions making possible its application in clinical radiology. Properties of standard Fricke gel dosimeter for high dose levels are used as starting point and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose dependency, actually showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain a good enough dosimeter response for low dose levels. A suitable composition among those studied is selected as a good candidate for low dose level radiation dosimetry consisting on a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, xylenol orange and ultra-pure reactive grade water. Dosimeter samples are prepared in standard vials for its in phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated by typical kV X-ray tubes and calibrated Farmer type ionization chamber is used as reference to measure dose rates inside phantoms in at vials locations. Once sensitive material composition is already optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. According to

  10. Role of mitochondria in radiation sensitivity

    International Nuclear Information System (INIS)

    This paper describes mainly the role of mitochondrial (Mt) manganese superoxide dismutase (MnSOD) for deciding the radiation sensitivity of cells. The fact that Mt concerns with apoptosis has been shown by the finding that change in Mt membrane potential relates with the cell death. Mt has the electron transport system to yield the cellular energy molecule (ATP) and from which electrons are leaked out in 2-3%, a considerably large proportion in a cell. The electrons react with oxygen nearby to yield SO (O2·-), which in turn induces apoptosis through oxidation stress (OS). On the other hand, MnSOD is transported in Mt from cytoplasm and excludes the reactive oxygen species (ROS) like SO. Studies by MnSOD gene-deletion, knockout, cDNA-transfection, and transgenesis have indicated MnSOD is essential for keeping life and resistance to OS. Authors have shown that overexpression of Mt MnSOD protects against radiation-induced cell death, suggesting that Mt participates in radiation sensitivity where SO is involved. Interestingly, MnSOD activity is low in cancer cells, its overexpression results in tumor suppression and MnSOD is a target in leukemia therapy. When MTS (Mt targeting sequence, necessary for the enzyme to enter Mt)-deleted MnSOD is transfected, cells lack resistance to radiation, indicating the enzyme must be present in Mt. Mt DNA damage leading to electron transport system impairment is found to increase ROS, and to be reversed by the transfection of MnSOD gene. Studies of Mt DNA damage in cancer cells where aerobic glycolysis is actively operated, are currently in progress lively, and are thought to promote the development of diagnosis and treatment of cancer. (R.T.)

  11. Radiation-Sensitive Mutants of CAENORHABDITIS ELEGANS

    OpenAIRE

    Hartman, Philip S.; Herman, Robert K.

    1982-01-01

    Nine rad (for abnormal radiation sensitivity) mutants hypersensitive to ultraviolet light were isolated in the small nematode Caenorhabditis elegans. The mutations are recessive to their wild-type alleles, map to four of the six linkage groups in C. elegans and define nine new games named rad-1 through rad-9. Two of the mutants—rad-1 and rad-2—are very hypersensitive to X rays, and three—rad-2, rad-3 and rad-4—are hypersensitive to methyl methanesulfonate under particular conditions of exposu...

  12. Directionally Sensitive Silicon Radiation Sensor (VCELL)

    Science.gov (United States)

    Cook, Koy B.

    2002-01-01

    Sensors are a mission critical element in many NASA programs and require some very unique properties such as small size, low power, high reliability, low weight. Low cost sensors offer the possibility of technology transfer to the public domain for commercial applications. One sensor application that is important to many NASA programs is the ability to point at a radiation source, such as the sun. Such sensors may be an integral part of the guidance and control systems in space platforms and in remote exploratory vehicles. Sun/solar pointing is also important for ground-based systems such as solar arrays. These systems are not required to be small and lightweight. However, if a sensor with a sun pointing capability was developed that is very small, rugged, lightweight and at the same time low cost, it certainly could be used in existing and perhaps many new ground based applications, The objective of the VCELL (Directionally Sensitive Silicon Radiation Sensor) research is to develop a new and very unique silicon based directionally sensitive radiation sensor which can be fabricated using conventional monolithic IC technologies and which will meet the above requirements. The proposed sensor is a novel silicon chip that is directionally sensitive to incident radiation, providing azimuth and elevation information on the incident radiation. The resulting sensor chip will be appropriate for integration into a silicon IC or useful in a hybrid structure to be interfaced with a standard IEEE 1451 bus interface IC to create an Intelligent Sensor. It is presently estimated that it will require about three man-years of effort to complete the VCELL research and development. This includes the optical, electrical, mechanical and silicon fabrication and testing as well as computer simulations and theoretical analysis and modeling including testing in simulated space environments, This report summarizes the sensor research completed this summer as part of the Summer Faculty

  13. Development of a radiation-sensitive indicator

    International Nuclear Information System (INIS)

    A poly(vinyl alcohol) (PVA) film containing acid-sensitive dye (bromophenol red, BPR) and water soluble chlorine-containing substance [CCl3COONa or chloral hydrate (CCl3CH(OH)2, 2,2,2-trichloroethan-1,1-diol)] may be useful as a radiation-sensitive indicator. The acid-sensitive dye in the film changes its color from violet to pale yellow by irradiation due to the consequent lowering of the pH of the film caused by the HCl generated from the radiolysis of the Cl-containing substance. This film can be used as a dosimeter in a relatively low dose range up to 5 kGy. This response range makes this film useful in some food irradiation, pasteurization and water purification applications. The effects of temperature and relative humidity during irradiation and post-irradiation storage on the response of the film are discussed. It is inexpensive, does not require toxic solvents in preparation and easy to prepare in a laboratory. (author)

  14. Radiation sensitization by inhibition of activated ras

    International Nuclear Information System (INIS)

    Background and purpose: Ras has been identified as a significant contributor to radiation resistance. This article reviews preclinical and phase I clinical studies that reported on combining inhibition of activated Ras and downstream effectors of Ras with radiotherapy. Material and methods: transfection studies and RNA interference were used to check the role of the Ras isoforms for intrinsic radiation sensibility. Western blotting was used to control for prenylation inhibition of the respective Ras isoforms and for changes in activity of downstream proteins. Clonogenic assays with human and rodent tumor cell lines served for testing radiosensitivity. In vivo, farnesyltransferase inhibitors (FTIs) and irradiation were used to treat xenograft tumors. Ex vivo plating efficiency measurements, regrowth of tumors, and EF5 staining for detection of hypoxia were endpoints in these studies. Simultaneous treatment with L-778,123 and irradiation was performed in non-small cell lung cancer, head and neck cancer, and pancreatic cancer patients. Results: radiation sensitization was achieved in vitro and in vivo blocking the prenylation of Ras proteins in cell lines with Ras activated by mutations or receptor signaling. Among the many Ras downstream pathways the phosphoinositide 3 (PI3) kinase-Akt pathway was identified as a contributor to Ras-mediated radiation resistance. Furthermore, increased oxygenation was observed in xenograft tumors after FTI treatment. Combined treatment in a phase I study was safe and effective. Conclusion: the rational combination of FTIs with radiotherapy may improve the clinical results of patients with tumors who bear mutant or receptor-signaling activated Ras. (orig.)

  15. Gamma radiation sensitivity in Nigella sativa L

    International Nuclear Information System (INIS)

    Gamma irradiation induced mutagenic sensitivity of Nigella sativa L. (black cummin) was assessed from R1 attributes like frequency of seed germination, rate of seedling growth, chromosomal anomalies and sterility types, following exposures of dry dormant seed samples (1.8 % moisture content) to 5 KR, 10 KR, 20 KR, 30 KR, 40 KR, 50 KR and 60 KR of γ-irradiations. Results indicated that gamma radiations have induced both physiological and chromosomal disturbances. LD50 was found to lie between 20 KR and 30 KR of γ-ray. Treatments beyond 30 KR of irradiation were found to be lethal due to complete failure of emergence of seedlings in the field conditions; although 5 KR has shown stimulation in mitotic index. Sterility types have possibly appeared as an outcome of meiotic disturbances. (author)

  16. Sensitiveness of viruses to gamma radiation

    International Nuclear Information System (INIS)

    The sensitiveness of viruses to gamma rays was compared using eight viruses suspended with low concentration in drinking water, and four viruses present in high concentrations in tissue culture medium. The results show that the following factors are responsible for the resistance of viruses to gamma rays: 1. type of virus: the specific radiation resistance varied considerably; in general, there was a closer correlation with the general resistance of the virus to chemico-physical influences than with the type of nucleic acid of the virus examined; 2. medium of suspension and state of aggregation: high protein content and lyophilisation increased the resistance to gamma rays widely; 3. virus concentration: the virus reduction by a factor of 10 in suspensions with high virus concentration needed a higher radiation dose compared with suspensions of low virus content. All the results demonstrate the kinetics of inactivation to be a 1st order reaction. The increase of temperature to 410C did not show any significant influence. (orig.)

  17. Sensitivity of viruses to radiation sterilization

    International Nuclear Information System (INIS)

    kGy, the reduction of 9 (6+3) log 10 units, or a dose of 36 kGy, would be required, and if D 10 is 5.6 kGy, than a dose >50 kGy would be needed to inactivate HIV (Conway and Tomford , CID 14: 978, 1992). These results are in agreement with data published by Fideler et al. (J Bone Jnt Surg.76A: 1032, 1994) who found that doses of 30-40 kGy are required to inactivate HIV in fresh frozen bone allografts. The doses cited above exceed the dose of 25 kGy currently recommended and commonly used by many tissue banks in the world with the exception of the Central Tissue Bank in Warsaw, where the dose of 33 kGy + 10% has been routinely used since 1963. Taking into consideration the results cited above it seems advisable to increase the sterilizing dose for tissue allografts at least up to 35 kGy. It should be kept in mind, however, that high doses of ionizing radiation can evoke numerous chemical and physical changes which may affect the quality of tissue allografts, such as the mechanical properties of bone or other connective tissue grafts or the osteoinductive capacity of bone allografts as well as their resorption rate. It has been observed, however, that radiation-induced changes in quality of tissue allografts depend on two groups of factors: i) conditions of irradiation (dose, temperature) and ii) the method of preservation (deep-freezing, lyophilization). These factors may dramatically influence the radiation damage of collagen a major constituent of connective tissue allografts. Further studies are needed on the effect of radiation sterilization conditions and preservation procedures on degradation of connective tissue allograft constituents

  18. Comparative study of different surrogate markers for individual radiation sensitivity

    International Nuclear Information System (INIS)

    Radiotherapy is an important part of therapeutic tumor treatment concept. The applied total dose is limited by the unavoidable radiation effect on the surrounding normal tissue and the risk of radiation induced acute or chronic side effects. The clinical radiation sensitivity, i.e. the risk of radiogenic side effects is strongly coupled to the cellular radiation sensitivity. The contribution is focused on the development of a predictive tool for the individual radiation sensitivity for individual radiotherapeutic planning using lymphocytes. Residual foci, i.e. accumulated repair associated proteins at the residual double strand break are supposed to be surrogate markers of the cellular radiation sensitivity. No relation between the foci detection and the G(0)/G(1) was found assay with respect to the individual radiation sensitivity.

  19. Metal-containing radiation-sensitive polymers

    International Nuclear Information System (INIS)

    The copolymers of methyl methacrylate with alkali metal salts (Na, K, and Cs) of methacrylic acid have been prepared by saponification K, and Cs) of methylacrylic acid have been prepared by saponification of the homopolymer poly(methyl methacrylate), PMMA. Low degrees of hydrolysis have been achieved by a heterogeneous system, and from the infrared spectra it has been confirmed that the ester groups of the methyl methacrylates are directly converted to the metal salts of methacrylic acid. These ionomers exhibit pseudo high molecular weights in gel permeation chromatogram, but no appreciable increase in intrinsic viscosities is observed in comparison to PMMA. The coordinated inorganic polymers poly[(dithio-2,2'-diacetato)bis(dimethylsulfoxide)dioxouranium(VI)] and poly[{methylenebis(thio)-2,2'-bis(acetato)}bis(dimethylsulfoxide)dioxouranium(VI)]have been synthesized in dimethyl sulfoxide solution with about 90% yield. The degree of polymerization and the number of average molecular weights of these polymers have been assessed by high resolution nuclear magnetic resonance, with which the acetato end group to the bridging ligand group ratios have been determined. The polymers bridging ligand group ratios have been determined. The polymers have been characterized by employing various techniques: infrared spectra, thermal gravimetric analysis, 13C solid state nuclear magnetic resonance, and gel permeation chromatography. The prepared polymer samples have been subjected to various doses of 137Cs gamma radiation under which the polymers predominantly undergo chain scission. The radiation sensitivities of the polymers are assessed by G values which are obtained from gel permeation chromatograms. These uranyl polymers exhibit unusually high G values

  20. Metal-containing radiation-sensitive polymers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, A.Y.

    1986-01-01

    The copolymers of methyl methacrylate with alkali metal salts (Na, K, and Cs) of methacrylic acid have been prepared by saponification K, and Cs) of methylacrylic acid have been prepared by saponification of the homopolymer poly(methyl methacrylate), PMMA. Low degrees of hydrolysis have been achieved by a heterogeneous system, and from the infrared spectra it has been confirmed that the ester groups of the methyl methacrylates are directly converted to the metal salts of methacrylic acid. These ionomers exhibit pseudo high molecular weights in gel permeation chromatogram, but no appreciable increase in intrinsic viscosities is observed in comparison to PMMA. The coordinated inorganic polymers poly((dithio-2,2'-diacetato)bis(dimethylsulfoxide)dioxouranium(VI)) and poly()methylenebis(thio)-2,2'-bis(acetato))bis(dimethylsulfoxide)dioxouranium(VI))have been synthesized in dimethyl sulfoxide solution with about 90% yield. The degree of polymerization and the number of average molecular weights of these polymers have been assessed by high resolution nuclear magnetic resonance, with which the acetato end group to the bridging ligand group ratios have been determined. The polymers bridging ligand group ratios have been determined. The polymers have been characterized by employing various techniques: infrared spectra, thermal gravimetric analysis, /sup 13/C solid state nuclear magnetic resonance, and gel permeation chromatography. The prepared polymer samples have been subjected to various doses of /sup 137/Cs gamma radiation under which the polymers predominantly undergo chain scission. The radiation sensitivities of the polymers are assessed by G values which are obtained from gel permeation chromatograms. These uranyl polymers exhibit unusually high G values.

  1. Radiation sensitivity of adult human parenchymal hepatocytes

    International Nuclear Information System (INIS)

    The purpose of this study was to determine the radiosensitivity and repair kinetics of adult human parenchymal hepatocytes. Discarded viable human liver was obtained from the surgical pathology laboratory, and the cells were enzymatically isolated via a modification of the 2-step in situ collagenase perfusion technique used for the rat. The isolated hepatocytes were cultured with MEM media (10% FCS) in collagen coated 60 mm plates. Three hr after the cells were placed in culture, the media was changed to remove any dead unattached hepatocytes. After 24hr the viable hepatocytes were removed from the plates with collagenase and irradiated (40C, 21% O/sub 2/) with /sup 60/Co (1 Gy/min). The alkaline elution technique was used to quantify the single strand breaks (SSB). A linear dose response curve was obtained when the strand scission factor was plotted versus radiation dose and the slopes for the rat (4 cases) and human hepatocytes (6 cases) were 0.0302 and 0.0221 Gy/sup -1/, respectively. Thus, human hepatocytes are approximately 25% more radioresistant than those from the rat; this correlates with the GSH levels in the human hepatocytes (15 mM) being 20% greater than that in rat hepatocytes (12 mM). In contrast, the kinetics of repair of SSB in human hepatocytes was t/sub 1/2 fast/ = 20 min. t/sub 1/2 slow/ = 267 min) approximately 3 times slower than that in rat hepatocytes (t/sub 1/2 fast/ = 6 min, t/sub 1/2 slow/ = 98 min) and after 3 hr of repair the percent of the initial damage remaining was 20% and 15%, respectively. These date imply that in comparison to rat hepatocytes, human hepatocytes would be more radioresistant to large single doses, but equal if not more sensitive to fractionated radiation treatment

  2. Radiation sensitivity of hyperthermal composting microorganisms

    Science.gov (United States)

    Choi, Jong-Il; Yoon, Min-Chul; Kim, Jae-Hun; Yamashita, Masamichi; Kim, Geun Joong; Lee, Ju-Woon

    In the space station and vehicles designed for long human mission, high-temperature compost is a promising technology for decomposing organic waste and producing the fertilizers. In space, the microorganisms could have the changed biological activities or even be mutated by ionizing irradiation. Therefore, in this study, the effect of gamma irradiation on the sensitivity of bacteria in hyperthermal composting was investigated. The sequence analysis of the amplified 16s rDNA genes and amoA gene were used for the identification of composting microorganisms. Viability of microorganisms in compost soil after gamma irradiation was directly visualized with LIVE/DEAD Baclight viability kit. The dominant bacterial genera are Weissella cibaria and Leuconostoc sp. and fungus genera are Metschnikowia bicuspidate and Pichia guilliermondii, respectively. By the gamma irradiation up to the dose of 1 kGy, the microbial population was not changed. Also, the enzyme activities of amylase and cellulose were sustained by the gamma irradiation. These results show that these hyperthermia microorganisms might have the high resistance to gamma radiation and could be used for agriculture in the Space Station.

  3. Acetylene-sensitized radiation crosslinking of polytetrafluoroethylene

    International Nuclear Information System (INIS)

    The radiation crosslinking of polytetrafluoroethylene (PTFE) in the presence of acetylene under γ radiation (60Co) at a dose rate of 2 Gy/s up to absorbed doses of 20-60 kGy was studied. The yield of crosslinking was determined from thermomechanical testing data and, on this basis, it was concluded that crosslinking follows the chain mechanism. Radiation-crosslinked PTFE is shown to possess high wear resistance and enhanced radiation stability

  4. Ionizing radiation affects active ileal electrolyte transport

    International Nuclear Information System (INIS)

    Exposure to ionizing radiation has pronounced effects on gastrointestinal physiology eliciting the fluid and electrolyte loss of the gastrointestinal syndrome. This study reports on the effect of whole-body cobalt-60 exposure on active electrolyte transport by rabbit ileum in an effort to quantify these changes and to define the mechanism by which electrolyte transport is altered. The short-circuit current (lsc), a measure of active electrolyte transport, was determined for ileal segments isolated from rabbits radiated with 5 to 100 Gy and compared to those from sham irradiated control 1 to 96 hours after exposure. One hour after exposure there was no apparent effect of radiation. However by 24 hours, there was a significant increase in lsc of segments from animals exposed to doses of 7.5 Gy and greater. The lsc remained elevated during the 96 hours for 10 and 12 Gy whereas at 7.5 Gy it returned to control values by 72 hours. The response of the tissue to a secretagogue, theophylline, was reduced 72 hours post-irradiation. By 96 hours after exposure, the response to an actively transported amino acid, alanine, was also reduced. These results indicate that radiation-induced fluid and electrolyte loss is not simply a consequence of denudiation of the intestine but due in part to alterations in cellular transport processes

  5. Sensitivity of transient synchrotron radiation to tokamak plasma parameters

    Energy Technology Data Exchange (ETDEWEB)

    Fisch, N.J.; Kritz, A.H.

    1988-12-01

    Synchrotron radiation from a hot plasma can inform on certain plasma parameters. The dependence on plasma parameters is particularly sensitive for the transient radiation response to a brief, deliberate, perturbation of hot plasma electrons. We investigate how such a radiation response can be used to diagnose a variety of plasma parameters in a tokamak. 18 refs., 13 figs.

  6. Maternal Glucose Tolerance in Pregnancy Affects Fetal Insulin Sensitivity

    OpenAIRE

    Luo, Zhong-Cheng; Delvin, Edgard; Fraser, William D.; Audibert, Francois; Deal, Cheri I.; Julien, Pierre; Girard, Isabelle; Shear, Roberta; Levy, Emile; Nuyt, Anne-Monique

    2010-01-01

    OBJECTIVE Offspring of mothers with impaired glucose tolerance are far more likely to develop type 2 diabetes. We tested the hypothesis that maternal glucose tolerance in pregnancy affects fetal insulin sensitivity or β-cell function. RESEARCH DESIGN AND METHODS In a prospective singleton pregnancy cohort study, we analyzed glucose, insulin, and proinsulin concentrations in maternal blood at the 50-g oral glucose tolerance test (OGTT) at 24–28 weeks of gestation and in venous cord blood (n = ...

  7. Factors Affecting Sensitivity of Variable Charge Soils to Acid Rain

    Institute of Scientific and Technical Information of China (English)

    WANGJING-HUA

    1995-01-01

    The sensitivity of a large number of variable charge soils to acid rain was evaluated through examining pH-H2SO4 input curves.Two derivative parameters,the consumption of hydrogen ions by the soil and the acidtolerant limit as defined as the quantity of sulfuric acid required to bring the soil to pH 3.5 in a 0.001mol L-1 Ca(NO3)2 solution,were used.The sensitivity of variable charge soils was higher than that of constant charge soils,due to the predominance of kaolinite in clay mineralogical composition.Among these soils the sensitivity was generally of the order lateritic red soil>red soil> latosol.For a given type of soil within the same region the sensitivity was affected by parent material,due to differences in clay minerals and texture.The sensitivity of surface soil may be lower or higher than that of subsiol,depending on whether organic matter or texture plays the dominant role in determining the buffering capacity.Paddy soils consumed more acid within lower range of acid input when compared with upland soils,due to the presence of more exchangeable bases,but consumed less acid within higher acid input range,caused by the decrease in clay content.

  8. Relative radiation sensitivity of insulators, stabilizers, and superconductors

    International Nuclear Information System (INIS)

    The objective of this work was to compare the radiation sensitivity of the various parts of superconducting magnet systems. Using the radiation spectra calculated by Engholm for the Engineering Test Facility (ETF) toroidal field magnet inboard leg and available data on radiation effects, commonly used magnet components were ranked in order of radiation sensitivity. It was found that epoxy-based insulators and copper and aluminum stabilizers were the most sensitive parts of the magnets, more sensitive than the superconductors. Use of polyimide-based insulators would make the insulators less vulnerable than the stabilizers and superconductors. An experiment is planned to study the effects of various degrees of cold work on the radiation-induced magnetoresistance of copper, since this will be an important factor for fusion magnet stabilizers

  9. Radiation damage test of position sensitive silicon detectors

    International Nuclear Information System (INIS)

    A study of radiation damage of position sensitive silicon detectors (PSDs), for use as a position monitor of high energy heavy ion beams, was carried out. It is revealed that the position linearity of the standard PSD is strongly affected even by an absorbed dose around 100 Gy. The reason of the distortion of position linearity was considered to be a positive charge build-up in the SiO2 layer covering the PSD. To overcome the problem, new types of PSDs have been developed raising impurity density in the resistive layer and removing the SiO2 layer. A PSD with a distortion of less than 100 μm over an effective area of 13 mm x 13 mm is obtained which is usable as a heavy ion beam monitor. (orig.)

  10. Influence of sensitizing additives on deformation-strength properties of radiation vulcanized rubber

    International Nuclear Information System (INIS)

    Full text: Expanding the practical use of products of radiation-vulcanized elastopolymers (RVEP) makes it necessary to increase their operational properties. Applied to the exploitation of polymers in the field of the ionizing radiation does not always meet shown requirements to them. In the present report the influence of sensitizer of disulpho chloride aromatic compounds on deformation-strength and their ageing under the influence of radiation exposure is being examined. The serial produced aromatic compounds of disulpho chloride bezene (DSCB) were used as sensitizers. It is established that, during the sensitization of radiation chemical vulcanization the mixture of butadiene-nitrile rubber with PVC with other ingredients affect the density of the spatial grid which determines the mechanical properties of vulcanized rubber. Two processes simultaneously run in the presence of sensitizing additives: inhibition of radiation oxidation which causes cross-linking and formation of the spatial grid in BNC. The role of sensitizer in the process of radiation vulcanization is defined first of all by reducing the doze of irradiation in the vulcanization process; simultaneously accelerate the cross-linking of the polymer chains. On the base of physical mechanical and structure of DSCB, can be judged that the influence of ionizing radiation leads the polar groups to ionization besides, their excited potential during ionization is very high which provides material with radiation resistance. Considering the resistance of DSCB to radiation, its practical value is high and can conduct vulcanization at low doses (150-300 kGy). (authors)

  11. High sensitivity radiation detector for capillary electrophoresis

    International Nuclear Information System (INIS)

    Capillary electrophoresis is an important new instrumental technique capable of high resolution separation and analysis of small quantities of nucleotides, amino acids, peptides, and proteins with very high efficiency and throughput. The unprecedented sensitivity of this technique will be useful for such new applications as in vivo labeling and identification of trace substances and single cell work. The principle limitation of this technique for radiolabeled molecules has been identified as the sensitivity of the detector, primarily due to the small sample volume (32P-labeled biomolecules with unprecedented sensitivity. This detector can be easily retrofitted into existing CE apparatus

  12. Hunger state affects both olfactory abilities and gustatory sensitivity.

    Science.gov (United States)

    Hanci, Deniz; Altun, Huseyin

    2016-07-01

    Chemical senses such as odor, taste and appearance are directly related with appetite. Understanding the relation between appetite and flavor is getting more important due to increasing number of obese patients worldwide. The literature on the studies investigating the change in olfactory abilities and gustatory sensitivity mostly performed using food-related odors and tastes rather than standardized tests were developed to study olfaction and gustation. Therefore, results are inconsistent and the relationship between olfactory and gustatory sensitivity with respect to the actual state of human satiety is still not completely understood. Here, for the first time in literature, we investigated the change in both olfactory abilities and gustatory sensitivity in hunger and in satiety using 123 subjects (37 men, 86 women; mean age 31.4 years, age range 21-41 years). The standardized Sniffin' Sticks Extended Test and Taste Strips were used for olfactory testing and gustatory sensitivity, respectively. TDI score (range 1-48) was calculated as the collective scores of odor threshold (T), odor discrimination (D) and odor identification (I). The evaluation was performed in two successive days where the hunger state of test subjects was confirmed by blood glucose test strips (mean blood glucose level 90.0 ± 5.6 mg/dl in hunger and 131.4 ± 8.1 mg/dl in satiety). The results indicated statistically significant decrease in olfaction in satiety compared to hunger (mean TDI 39.3 ± 1.1 in hunger, 37.4 ± 1.1 in satiety, p < 0.001). The comparison of gustatory sensitivity indicated significantly higher sensitivity to sweet, sour and salty in hunger (p < 0.001), but significantly higher sensitivity to bitter tastant in satiety (p < 0.001). With this prospective study, we were able to show that both olfactory abilities and gustatory sensitivity were affected by hunger state. PMID:25744049

  13. Potential for radiation sensitizers and possible strategy for use

    International Nuclear Information System (INIS)

    The search for radiation sensitizers for use in radiotherapy is based on the assumption that proper use of these compounds will provide a differential sensitization of tumor and normal tissue. Based on the evidence that hypoxic cells exist within human tumors but not within normal cell populations, there is reason to believe that specific sensitizers of hypoxic cells might provide useful therapeutic benefit. This paper discusses the possible advantages of such sensitizers, over reliance on the phenomenon of reoxygenation, and describes very briefly the current status of hypoxic cell sensitizers. Finally a proposal is made concerning the way in which such sensitizers might be tested for their efficacy in human radiotherapy

  14. Inheritance of induction radiation sensitivity of space flight environments and γ-radiation on rice

    Science.gov (United States)

    Xu, J.; Wang, J.; Wei, L.; Li, Z.; Sun, Y.

    There are many factors affecting living things during space flight, such as microgravity, cosmic radiation, etc. A large number of plant mutants have been obtained after space flight on satellite in China in the last decade and some commercial crop varieties were released. However, little consideration has so far been given to the genetic mechanisms underlying sensitivity of plant seeds to space flight environments. To reveal the genetic mechanisms associated with induction radiation sensitivity (IRS), a set of 226 recombination inbred lines (RILs) derived from Lemont (japonica)/ Teqing (indica) F13, were analyzed using 164 well-distributed DNA markers and assayed for the traits related to IRS including rate of survival seedling (RSS), seedling height (SH), seed setting rate (SSR) and total physiological damage (TPD) in replicated trials after space flight on Chinese Shenzhou IV Spacecraft andγ -radiation treatment (35000 rad) on the ground in 2002. Seedling growth of Lemont was accelerated after space flight with the SH of 116.2% of ground control while growth suppression was happened for Teqing with the SH of 85.7% of ground control. γ -radiation treatment resulted in significant decrease in all tested traits for the two parents, indicating space flight and γ -radiation treatment had different biological effects on the two parents. Significant differences were detected among the RILs for their responses to space flight environments and γ -radiation, reflected as the difference in the four tested traits. Space flight resulted in stimulation on growth for 57.1% lines whileγ -radiation had suppression on growth for most lines. Seventeen putative main-effect QTLs was identified for the four traits related to IRS under space flight and γ -radiation, which totally explained significant portions of the total trait variation (4.4% for RSS, 27.2% for SH, 4% for SSR and 15.8% for TPD for space flight; 10.4% for RSS, 15.1% for SH, 8.2% for SSR and 6.1% for TPD for

  15. On the instability effects in radiation-sensitive chalcogenide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Balitska, V. [Lviv State University for Vital Activity Safety, 35 Kleparivska str., Lviv, UA-79007 (Ukraine); Lviv Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv, UA-79031 (Ukraine); Kovalskiy, A. [Lviv Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv, UA-79031 (Ukraine); International Materials Institute for New Functionality in Glass, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States); Shpotyuk, O. [Lviv Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv, UA-79031 (Ukraine); International Materials Institute for New Functionality in Glass, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015-3195 (United States)], E-mail: shpotyuk@novas.lviv.ua; Vakiv, M. [Lviv Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv, UA-79031 (Ukraine)

    2007-04-15

    The features of application of radiation-sensitive media based on chalcogenide glasses of As-Ge-S system for registration of high-energy {gamma}-radiation are analysed. It is shown that compositional features of the observed time-instability effect should be taken into account in order to ensure a higher accuracy of the developed dosimeters.

  16. On the instability effects in radiation-sensitive chalcogenide glasses

    International Nuclear Information System (INIS)

    The features of application of radiation-sensitive media based on chalcogenide glasses of As-Ge-S system for registration of high-energy γ-radiation are analysed. It is shown that compositional features of the observed time-instability effect should be taken into account in order to ensure a higher accuracy of the developed dosimeters

  17. The Visualization of Infrared Radiation Using Thermal Sensitive Foils

    Science.gov (United States)

    Bochnícek, Zdenek

    2013-01-01

    This paper describes a set of demonstration school experiments where infrared radiation is detected using thermal sensitive foils. The possibility of using standard glass lenses for infrared imaging is discussed in detail. It is shown that with optic components made from glass, infrared radiation up to 2.5 µm of wavelength can be detected. The…

  18. Guide for use of radiation-sensitive indicators. 2. ed.

    International Nuclear Information System (INIS)

    This guide covers the use of radiation-sensitive indicators in radiation processing. These indicators may be labels, papers, inks or packaging materials which undergo a color change or become colored when exposed to ionizing radiation. The purpose of these indicators is to determine visually whether or not a product has been irradiated, rather than to measure different dose levels. Such materials are not dosimeters and should not be used as a substitute for proper dosimetry. Information about dosimetry systems for ionizing radiation is provided in other ASTM and ISO/ASTM documents (see ISO/ASTM Guide 51261

  19. Characterization of UV radiation sensitive frog cell lines

    International Nuclear Information System (INIS)

    Twenty-one subclones of nine frog cell isolates were tested for sensitivity to a panel of DNA damaging agents. Two clones were identified which had a greater than wild type level of sensitivity to UV radiation but had a wild type level of sensitivity to the other agents. These clones were the haploid RRP602-7 and the diploid RRP802-1. RRP802-1 was found to be unstable with respect to UV sensitivity. The line was cloned in order to isolate stable sensitive and wild type derivatives. RRP802-1-16, a UV sensitive clone and RRP802-1-13, a clone with a wild type level of sensitivity to UV radiation, were isolated. The UV radiation sensitivity of RRP602-7, RRP802-1 and RRP802-1-16 did not correlate with cell size, cell shape, cell cycle distribution or ploidy. The cell cycle distribution after UV irradiation, the rate of DNA synthesis after UV-irradiation, the DNA polymerase α activity and the sister chromatid exchange frequency were all measured in RRP602-7, RRP802-1 and RRP802-1-16 in order to examine the DNA repair capacity. The presence of DNA repair pathways was examined directly in RRP602-7, RRP802-1 and RRP802-1-16. All were found to be proficient in photo-reactivation repair and postreplication repair of UV elicited DNA damage

  20. Radiation sensitization studies by silymarin on HCT-15 cells

    International Nuclear Information System (INIS)

    Radiotherapy has been widely used for treatment of human cancers. However, cancer cells develop radioresistant phenotypes following multiple exposures to the treatment agent that decrease the efficacy of radiotherapy. Here it was investigated that the radiation sensitization effects of silymarin found in colon cancer. The aim of this study was to investigate mechanisms involved in radiation sensitization growth inhibitory effect of silymarin in combination with radiation, in Human colon carcinoma (HCT-15). The human colon carcinoma was utilized and SRB-assay was performed to study anti-proliferative effect of silymarin in combination with gamma radiation (2 Gy) appropriate radiation dose was optimized and confirmed by clonogenic assay. Microscopic analysis was done by staining with Hoechst-33342, DAPI, Propidium iodide to confirm the presence of apoptosis. Nitric oxide production, changes in lipid peroxidation, Cell cycle analysis were carried out and mitochondrial membrane potential was measured by uptake of cationic dye JC-1 by using flow cytometer. Silymarin in combination with radiation (2 Gy) inhibited 70% ± 5% population growth of HCT-15 cells in time and dose dependent manner. Pre treatment of cells with silymarin for 30 min before radiation was found to be most effective for radiation sensitization. There was 25% increase in levels of nitric oxide as compare to control, whereas 2.5 fold change in lipid peroxidation with respect to control. IR-induced apoptosis in HCT-15 cell line was significantly enhanced by silymarin, as reflected by viability, DNA fragmentation, and mitochondrial dysfunction. Additionally, silymarin in combination with IR is found to be effective in sensitization of HCT-15 cells. In vivo studies on development of tumor and sensitization aspects needs to done in future. (author)

  1. Radiation sensitive devices and systems for detection of radioactive materials and related methods

    Energy Technology Data Exchange (ETDEWEB)

    Kotter, Dale K

    2014-12-02

    Radiation sensitive devices include a substrate comprising a radiation sensitive material and a plurality of resonance elements coupled to the substrate. Each resonance element is configured to resonate responsive to non-ionizing incident radiation. Systems for detecting radiation from a special nuclear material include a radiation sensitive device and a sensor located remotely from the radiation sensitive device and configured to measure an output signal from the radiation sensitive device. In such systems, the radiation sensitive device includes a radiation sensitive material and a plurality of resonance elements positioned on the radiation sensitive material. Methods for detecting a presence of a special nuclear material include positioning a radiation sensitive device in a location where special nuclear materials are to be detected and remotely interrogating the radiation sensitive device with a sensor.

  2. Multipurpose High Sensitivity Radiation Detector: Terradex

    International Nuclear Information System (INIS)

    Terradex project aims to realise an accurate and programmable multiparametric tool which will measure relevant physical quantities such as observation time, energy and type of all decay products of three naturally occurring decay chains of uranium and thorium series present in nature as well as the decay products of man-made radioactivity. The measurements described in this work are based on the performance tests of the first version of an instrument that is designed to provide high counting accuracy, by introducing self-triggering, delayed time-coincidence technique, of products of a given decay chain. In order to qualify the technique and to calibrate the Terradex, a 222Rn source is used. The continuous and accurate monitoring of radon concentration in air is realised by observing the alpha and beta particles produced by the decay of 222Rn and its daughters and tag each of them with a precise occurrence time. The validity of delayed coincident technique by using the state of the art electronics with application of novel data sampling and analysis methods are discussed. The flexibility of sampling protocols and the advantages of online calibration capability to achieve the highest level of precision in natural and man-made radiation measurements are also described

  3. Multipurpose High Sensitivity Radiation Detector: Terradex

    Energy Technology Data Exchange (ETDEWEB)

    Alpat, Behcet [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy)]. E-mail: behcet.alpat@pg.infn.it; Aisa, Damiano [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Bizzarri, Marco [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Blasko, Sandor [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Esposito, Gennaro [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Farnesini, Lucio [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Fiori, Emmanuel [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Papi, Andrea [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Postolache, Vasile [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Renzi, Francesca [Dipartimento di Fisica dell' Universita di Perugia and INFN Sezione di Perugia (Italy); Ionica, Romeo [Politecnica University of Bucarest, Splaiul Indipendentei, Bucharest (Romania); Manolescu, Florentina [Space Science Institute of Bucharest, Maugurele, Bucharest (Romania); Ozkorucuklu, Suat [Suleyman Demirel Universitesi, Isparta (Turkey); Denizli, Haluk [Abant Izzet Baysal Universitesi, Bolu (Turkey); Tapan, Ilhan [Uludag Universitesi, Bursa (Turkey); Ercan Pilicer [Uludag Universitesi, Bursa (Turkey); Egidi, Felice [SITE Technology, Carsoli (Italy); Moretti, Cesare [SITE Technology, Carsoli(AQ) (Italy); Dicola, Luca [SITE Technology, Carsoli(AQ) (Italy)

    2007-05-11

    Terradex project aims to realise an accurate and programmable multiparametric tool which will measure relevant physical quantities such as observation time, energy and type of all decay products of three naturally occurring decay chains of uranium and thorium series present in nature as well as the decay products of man-made radioactivity. The measurements described in this work are based on the performance tests of the first version of an instrument that is designed to provide high counting accuracy, by introducing self-triggering, delayed time-coincidence technique, of products of a given decay chain. In order to qualify the technique and to calibrate the Terradex, a {sup 222}Rn source is used. The continuous and accurate monitoring of radon concentration in air is realised by observing the alpha and beta particles produced by the decay of {sup 222}Rn and its daughters and tag each of them with a precise occurrence time. The validity of delayed coincident technique by using the state of the art electronics with application of novel data sampling and analysis methods are discussed. The flexibility of sampling protocols and the advantages of online calibration capability to achieve the highest level of precision in natural and man-made radiation measurements are also described.

  4. Genetics of human sensitivity to ultraviolet radiation

    Science.gov (United States)

    Cleaver, James E.

    1994-07-01

    the major human health effects of solar and artificial UV light occur from the UVB and UVC wavelength ranges and involve a variety of short-term and long-term deleterious changes to the skin and eyes. the more important initial damage to cellular macromolecules involves dimerization of adjacent pyrimidines in DNA to produce cyclobutane pyrimidine dimes, (6-4) pyrimidine- pyrimidone, and (6-4) dewar photoproducts. these photoproducts can be repaired by a genetically regulated enzyme system (nucleotide excision repair) which removes oligonucleotides 29-30 nucleotides long that contain the photoproducts, and synthesizes replacement patches. At least a dozen gene products are involved in the process of recognizing photoproducts in DNA, altering local DNA helicity and cleaving the polynucleotide chain at defined positions either side of a photoproduct. Hereditary mutations in many of these genes are recognized in the human genetic disorders xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD). Several of the gene products have other functions involving the regulation of gene transcription which accounts for the complex clinical presentation of repair deficient diseases that involve sensitivity of the skin and eyes to UV light, increased solar carcinogenesis (in XP), demyelination, and ganglial calcification (in CS), hair abnormalities (in TTD), and developmental and neurological abnormalities

  5. Radiation sensitivity of food decay fungi

    International Nuclear Information System (INIS)

    Five species of food decay fungi, Aspergillus flavus, Asp. uiger, Penicillium sp., Botrytis cinerea and Rhizopus stolonifer, were examined for their radiosensitivity in several suspension media. Asp. flavus, Asp. niger and Penicillium sp. have almost the same sensitivity toward gamma rays, with D value in the range of 30 to 35 K rad, whereas Botrytis cinerea has a D value of approximately 55 K rad and Rhizopus stolonifer, the most resistant fungus studied, has a D value of approximately 100 K rad. Dry spores of Asp. flavus showed a considerable increase in their radioresistance when compared with spores irradiated in water. Asp. flavus and Penicillium sp. spores irradiated in citrate buffer at pH 3-7 showed almost no change in their radiosensitivity with pH, but Botrytis cinerea spores showed a distinct decrease in their radioresistance at pH 6 and 7. Penicillium sp. spores irradiated in sucrose solutions showed no significant change in their radioresistance. Botrytis cinerea spores displayed a higher radioresistance when they were irradiated in sucrose solution than in water. (author)

  6. Stromal sensitivity to radiation and hyperthermia

    International Nuclear Information System (INIS)

    The influence on stroma of heat alone, X-rays alone or the combined treatment, has been studied using the tumour bed effect (TBE) as an assay. Ca NT cells have been implanted into previously treated subcutaneous sites as an angiogenic stimulus. The vascular damage is then assessed by the reduced tumour growth rate. A range of X-ray doses was used and large alterations in latent period for growth to 2 mm diameter were followed by smaller alterations in the growth rate of established tumours. A dose reponse relationship was seen for latency and for growth rate. A range of subcutaneous temperatures was obtained by immersion in a water bath for 60 minutes at 400 to 44.50C. A slight retardation of tumour growth was seen after 41.50C, but an unexpected acceleration resulted from 44.50C. Combined heat and X-ray treatments showed thermal sensitization of the X-ray induced TBE at 41.50C, with a reversal at higher temperatures. At 430C and 44.50C a mild thermal burn was induced and this appeared to elicit neovascularisation that could be utilized by the implanted tumour cells. Delayed implantation of tumour cells abolished this effect. (author)

  7. DNA repair and radiation sensitivity in mammalian cells

    International Nuclear Information System (INIS)

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population

  8. Radiation vulcanization of natural rubber latex sensitized with commercial gases

    International Nuclear Information System (INIS)

    The industrial activities using natural rubber latex are fully compatible with rural areas in Amazon and other places in Brazil, as well as in other tropical countries. However the classical sulfur vulcanization presents many occupational problems for the workers in rural areas. Radiation vulcanization of natural rubber latex is a much more friendly process as sulfur compounds are not needed for crosslinking, although chemicals as acrylate monomers, particularly multifunctional acrylates are still used as sensitizers for radiation processes. Two commercial gases, acetylene and butadiene, were selected as sensitizers for the radiation vulcanization of natural rubber latex instead of acrylates. These gases accelerate the crosslinking rates of the cure process and lower the radiation dose required to achieve vulcanization of natural rubber latex and improve the mechanical properties to reduce the tackiness of rubber goods. (author)

  9. Radiation sensitivity as a genetic factor in carcinogenesis

    International Nuclear Information System (INIS)

    It is known that some association exists between cancer-prone hereditary diseases and radiation sensitivity. In the case of ataxia telagiectasia (AT), frequencies of ionizing radiation-induced mutations are believed to be lower in AT fibroblast cells than in normal cells. When employing lymphoblastoid cells, the AT cells exhibited the same gamma-ray-induced mutation rates in proportion to doses as the normal cells. Nevertheless, it is concluded that the AT cells do not exhibit induced mutations so readily as the normal cells, taking high sensitivity of AT cells to gamma-rays into account. This conclusion has led to concern about the relationship between carcinogenesis and mutation. To elucidate this, quantitative studies on mutation of oncogenes are required. It is also pointed out that the mechanism of cancer-prone hereditary diseases is uncertain. High sensitivity of the cells to certain mutagens does not necessarily reflect deficiency in damage repair, suggesting the possibility that there might be no association between carcinogenesis and high sensitivity to ionizing radiation. It remains to be elucidated whether DNA repair is involved in radiation sensitivity in the case of cancer-prone hereditary diseases including AT, except for the case of xeroderma pigmentosum. (Namekawa, K.)

  10. Radiation noise in a high sensitivity star sensor

    Science.gov (United States)

    Parkinson, J. B.; Gordon, E.

    1972-01-01

    An extremely accurate attitude determination was developed for space applications. This system uses a high sensitivity star sensor in which the photomultiplier tube is subject to noise generated by space radiations. The space radiation induced noise arises from trapped electrons, solar protons and other ionizing radiations, as well as from dim star background. The solar activity and hence the electron and proton environments are predicted through the end of the twentieth century. The available data for the response of the phototube to proton, electron, gamma ray, and bremsstrahlung radiations are reviewed and new experimental data is presented. A simulation was developed which represents the characteristics of the effect of radiations on the star sensor, including the non-stationarity of the backgrounds.

  11. Radiation-sensitive genetically susceptible pediatric sub-populations

    Energy Technology Data Exchange (ETDEWEB)

    Kleinerman, Ruth A. [National Cancer Institute, NIH, DHHS, Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, Rockville, MD (United States)

    2009-02-15

    Major advances in pediatric cancer treatment have resulted in substantial improvements in survival. However, concern has emerged about the late effects of cancer therapy, especially radiation-related second cancers. Studies of childhood cancer patients with inherited cancer syndromes can provide insights into the interaction between radiation and genetic susceptibility to multiple cancers. Children with retinoblastoma (Rb), neurofibromatosis type 1 (NF1), Li-Fraumeni syndrome (LFS), and nevoid basal cell carcinoma syndrome (NBCCS) are at substantial risk of developing radiation-related second and third cancers. A radiation dose-response for bone and soft-tissue sarcomas has been observed in hereditary Rb patients, with many of these cancers occurring in the radiation field. Studies of NF1 patients irradiated for optic pathway gliomas have reported increased risks of developing another cancer associated with radiotherapy. High relative risks for second and third cancers were observed for a cohort of 200 LFS family members, especially children, possibly related to radiotherapy. Children with NBCCS are very sensitive to radiation and develop multiple basal cell cancers in irradiated areas. Clinicians following these patients should be aware of their increased genetic susceptibility to multiple primary malignancies enhanced by sensitivity to ionizing radiation. (orig.)

  12. Variations in Maternal 5-HTTLPR Affect Observed Sensitive Parenting

    Science.gov (United States)

    Cents, Rolieke A. M.; Kok, Rianne; Tiemeier, Henning; Lucassen, Nicole; Székely, Eszter; Bakermans-Kranenburg, Marian J.; Hofman, Albert; Jaddoe, Vincent W. V.; IJzendoorn, Marinus H.; Verhulst, Frank C.; Lambregtse-van den Berg, Mijke P.

    2014-01-01

    Background: Little is known about the genetic determinants of sensitive parenting. Two earlier studies examined the effect of the serotonin transporter polymorphism (5-HTTLPR) on sensitive parenting, but reported opposite results. In a large cohort we further examined whether 5-HTTLPR is a predictor of observed maternal sensitivity and whether…

  13. Calmodulin affects sensitization of Drosophila melanogaster odorant receptors

    Directory of Open Access Journals (Sweden)

    Latha eMukunda

    2016-02-01

    Full Text Available Flying insects have developed a remarkably sensitive olfactory system to detect faint and turbulent odor traces. This ability is linked to the olfactory receptors class of odorant receptors (ORs, occurring exclusively in winged insects. ORs form heteromeric complexes of an odorant specific receptor protein (OrX and a highly conserved co-receptor protein (Orco. The ORs form ligand gated ion channels that are tuned by intracellular signaling systems. Repetitive subthreshold odor stimulation of olfactory sensory neurons sensitizes insect ORs. This OR sensitization process requires Orco activity. In the present study we first asked whether OR sensitization can be monitored with heterologously expressed OR proteins. Using electrophysiological and calcium imaging methods we demonstrate that D. melanogaster OR proteins expressed in CHO cells show sensitization upon repeated weak stimulation. This was found for OR channels formed by Orco as well as by Or22a or Or56a and Orco. Moreover, we show that inhibition of calmodulin (CaM action on OR proteins, expressed in CHO cells, abolishes any sensitization. Finally, we investigated the sensitization phenomenon using an ex vivo preparation of olfactory sensory neurons (OSNs expressing Or22a inside the fly’s antenna. Using calcium imaging, we observed sensitization in the dendrites as well as in the soma. Inhibition of calmodulin with W7 disrupted the sensitization within the outer dendritic shaft, whereas the sensitization remained in the other OSN compartments. Taken together, our results suggest that CaM action is involved in sensitizing the OR complex and that this mechanisms accounts for the sensitization in the outer dendrites, whereas further mechanisms contribute to the sensitization observed in the other OSN compartments. The use of heterologously expressed OR proteins appears to be suitable for further investigations on the mechanistic basis of OR sensitization, while investigations on native

  14. Radiation sensitivity of pine wood nematodes in woodchips

    International Nuclear Information System (INIS)

    The radiation sensitivity of pine wood nematodes has been tested over a range of dose values with a cesium-137 irradiator. Lethal doses were found to lie in a range above 6-8 kGy, too high to make this an economically attractive means of deinfestation for commercial woodchips. (author)

  15. DNA-nuclear matrix interactions and ionizing radiation sensitivity

    International Nuclear Information System (INIS)

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

  16. Radiation-induced apoptosis in thymocytes: pH sensitization

    International Nuclear Information System (INIS)

    Thymocytes were used as a model system to study the effect of microenvironmental pH changes on the radiation-induced apoptosis. We found that the sensitivity of thymocytes toward radiation induced apoptosis is increased by increasing the pH of the incubation medium. The major sensitivity change occurs between pH 7 and 8. In a given cell suspension the results obtained were similar when the apoptosis evaluation was carried out either by counting the picnotic nuclei, or monitoring the fraction of apoptic nuclei by flow cytometry; both methods show a radiosensitization when the pH value of incubation media rises from 7 to 8. These results may be important when 'in vitro' experiments are performed with lymphoid cells, since changes in pH of the media may determine important changes in the results. (orig.)

  17. Importance and sensitivity of parameters affecting the Zion Seismic Risk

    Energy Technology Data Exchange (ETDEWEB)

    George, L.L.; O' Connell, W.J.

    1985-06-01

    This report presents the results of a study on the importance and sensitivity of structures, systems, equipment, components and design parameters used in the Zion Seismic Risk Calculations. This study is part of the Seismic Safety Margins Research Program (SSMRP) supported by the NRC Office of Nuclear Regulatory Research. The objective of this study is to provide the NRC with results on the importance and sensitivity of parameters used to evaluate seismic risk. These results can assist the NRC in making decisions dealing with the allocation of research resources on seismic issues. This study uses marginal analysis in addition to importance and sensitivity analysis to identify subject areas (input parameter areas) for improvements that reduce risk, estimate how much the improvement dfforts reduce risk, and rank the subject areas for improvements. Importance analysis identifies the systems, components, and parameters that are important to risk. Sensitivity analysis estimates the change in risk per unit improvement. Marginal analysis indicates the reduction in risk or uncertainty for improvement effort made in each subject area. The results described in this study were generated using the SEISIM (Systematic Evaluation of Important Safety Improvement Measures) and CHAIN computer codes. Part 1 of the SEISIM computer code generated the failure probabilities and risk values. Part 2 of SEISIM, along with the CHAIN computer code, generated the importance and sensitivity measures.

  18. Hypoxic cell sensitizers and heavy charged-particle radiations

    International Nuclear Information System (INIS)

    Stationary-phase populations of Chinese hamster V-79 cells were irradiated with 250 kV X-rays and the Bragg peaks (spread to a width of 4 cm) of energetic He-, C-, Ne-, and A-ion beams produced at the 184-inch cyclotron and BEVALAC ar Lawrence Berkeley Laboratory. Survival curves were generated with each radiation for cells suspended in air-saturated and nitrogen-saturated medium with and without sensitizer present. The oxygen enhancement ratios (OERs) measured for X-rays with 1 mM metronidazole and 0.5 nM misonidazole were 2.0 and 1.6 respectively. The OERs without sensitizer for He-,C-, Ne-, and A-ion Bragg peaks were 2.4, 1.7, 1.6 and 1.4 respectively. For each type of radiation tested the presence of hypoxic-cell sensitizers resulted in an additional reduction in the measured OERs, indicating that these drugs should be of benefit in the radiotherapy planned with these and other high LET radiations. (author)

  19. Sensitivity of aerosol direct radiative forcing to aerosol vertical profile

    OpenAIRE

    Chung, Chul E.; Choi, Jung-Ok

    2014-01-01

    Aerosol vertical profile significantly affects the aerosol direct radiative forcing at the TOA level. The degree to which the aerosol profile impacts the aerosol forcing depends on many factors such as presence of cloud, surface albedo and aerosol single scattering albedo (SSA). Using a radiation model, we show that for absorbing aerosols (with an SSA of 0.7–0.8) whether aerosols are located above cloud or below induces at least one order of magnitude larger changes of the aerosol forcing tha...

  20. Radioprotective effect of garlic extract on some bacterial strains with different radiation sensitivities

    International Nuclear Information System (INIS)

    The radioprotective effect of garlic on four bacterial strains with different degrees of radiation sensitivities was investigated. The presence of garlic led to an increase in d-10 value of Ps. Aeruginosa, S. aureus and S. typhimurium by 160%, 50%, and 30% respectively. The protective efficiency of garlic against radiation was noticed to be proportional to its concentration in a given inoculum size. Garlic extract up to 180 micro liter per 108 inoculum size of B. cereus showed no protective effect. This fact was attributed to the existence of sulphur compounds in the given strain. Higher garlic concentrations appeared to affect the cloning efficiency of a given strain. 4fig., 2tab

  1. Gamma response study of radiation sensitive MOSFETs for their use as gamma radiation sensor

    Science.gov (United States)

    Srivastava, Saurabh; Aggarwal, Bharti; Singh, Arvind; Kumar, A. Vinod; Topkar, Anita

    2016-05-01

    Continuous monitoring of gamma dose is important in various fields like radiation therapy, space-related research, nuclear energy programs and high energy physics experiment facilities. The present work is focused on utilization of radiation-sensitive Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) to monitor gamma radiation doses. Static characterization of these detectors was performed to check their expected current-voltage relationship. Threshold voltage and transconductance per unit gate to source voltage (K factor) were calculated from the experimental data. The detector was exposed to gamma radiation in both, with and without gate bias voltage conditions, and change in threshold voltage was monitored at different gamma doses. The experimental data was fitted to obtain equation for dependence of threshold voltage on gamma dose. More than ten times increase in sensitivity was observed in biased condition (+3 V) compared to the unbiased case.

  2. How far is cancer cured by radiation sensitization?

    International Nuclear Information System (INIS)

    Some types of cancer are not cured by radiation alone in view of histology, location, and size. In facing so-called radioresistant cancer, antineoplastic agents, hypoxic cell sensitizers, biological response modifiers, or hyperthermia are used in combination with radiation, with the aim of cancer cure. First of all, this chapter discusses the subject of 'what is tumor cure by radiation therapy'. Current conditions of the aforementioned combined modalities and the future perspectives are presented. The following subjects are covered: (1) tumor control - significance of the number of stem cells; (2) biological evaluation of chemo-radiotherapy with cisplatin; (3) clinical results and experience with combination of radiotherapy and radiosensitizers; (4) radiosensitization with hypoxic cell radiosensitizers - present status (5) hypoxic cell radiosensitizers - present status and problems from the viewpoint of clinical radiotherapy; (6) thermal radiosensitization in vitro and its implications for radiotherapy; (7) clinical assessment of thermoradiotherapy for breast cancer and cancer of the urinary bladder; (8) interactions of radiation and biological response modifiers in the treatment of malignant tumor; (9) improvement in the effects of radiation therapy with biological response modifiers. (N.K.)

  3. The potential sensitivity of tropical plants to increased ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Little is known concerning the impact of stratospheric ozone depletion and increasing ultraviolet (UV)-B radiation on the phenology and growth of tropical plants. This is because, ostensibly, tropical plants are already exposed to relatively high levels of UV-B radiation (relative to a temperate environment) and should, therefore, possess a greater degree of tolerance to increased UV-B radiation. In this brief review I hope to show that, potentially, direct and indirect effects on photosynthesis, assimilate partitioning, phenology and biomass could occur in both tropical crops (e.g. cassava, rice) and native species (e.g. Cecropia obtusifolia (Bertol. Fl)., Tetramolopium humile (Gray), Nana sandwicensis L.). However, it should be noted that differences in sensitivity to UV-B radiation can be related to experimental conditions, and care should be taken to ensure that the quantity and quality of background solar radiation remains at near ambient conditions. Nevertheless, by integrating current and past studies on the impact of UV-B radiation on tropical species, I hope to be able to demonstrate that photosynthesis, morphology and growth in tropical plants could be directly affected by UV-B radiation and that UV-B radiation may be a factor in species and community dynamics in natural plant populations in the tropics

  4. Targeting Nucleophosmin 1 Represents a Rational Strategy for Radiation Sensitization

    International Nuclear Information System (INIS)

    Purpose: To test the hypothesis that small molecule targeting of nucleophosmin 1 (NPM1) represents a rational approach for radiosensitization. Methods and Materials: Wilde-type and NPM1-deficient mouse embryo fibroblasts (MEFs) were used to determine whether radiosensitization produced by the small molecule YTR107 was NPM1 dependent. The stress response to ionizing radiation was assessed by quantifying pNPM1, γH2AX, and Rad51 foci, neutral comet tail moment, and colony formation. NPM1 levels in a human-derived non-small-cell lung cancer (NSCLC) tissue microarray (TMA) were determined by immunohistochemistry. YTR107-mediated radiosensitization was assessed in NSCLC cell lines and xenografts. Results: Use of NPM1-null MEFs demonstrated that NPM1 is critical for DNA double- strand break (DSB) repair, that loss of NPM1 increases radiation sensitivity, and that YTR107-mediated radiosensitization is NPM1 dependent. YTR107 was shown to inhibit NPM1 oligomerization and impair formation of pNPM1 irradiation-induced foci that colocalized with γH2AX foci. Analysis of the TMA demonstrated that NPM1 is overexpressed in subsets of NSCLC. YTR107 inhibited DNA DSB repair and radiosensitized NSCLC lines and xenografts. Conclusions: These data demonstrate that YTR107-mediated targeting of NPM1 impairs DNA DSB repair, an event that increases radiation sensitivity

  5. Targeting Nucleophosmin 1 Represents a Rational Strategy for Radiation Sensitization

    Energy Technology Data Exchange (ETDEWEB)

    Sekhar, Konjeti R. [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Benamar, Mouadh [Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, Virginia (United States); Venkateswaran, Amudhan; Sasi, Soumya [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Penthala, Narsimha R.; Crooks, Peter A. [Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, Arkansas (United States); Hann, Stephen R. [Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Geng, Ling [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Balusu, Ramesh [Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas (United States); Abbas, Tarek [Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, Virginia (United States); Freeman, Michael L., E-mail: michael.freeman@vanderbilt.edu [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States)

    2014-08-01

    Purpose: To test the hypothesis that small molecule targeting of nucleophosmin 1 (NPM1) represents a rational approach for radiosensitization. Methods and Materials: Wilde-type and NPM1-deficient mouse embryo fibroblasts (MEFs) were used to determine whether radiosensitization produced by the small molecule YTR107 was NPM1 dependent. The stress response to ionizing radiation was assessed by quantifying pNPM1, γH2AX, and Rad51 foci, neutral comet tail moment, and colony formation. NPM1 levels in a human-derived non-small-cell lung cancer (NSCLC) tissue microarray (TMA) were determined by immunohistochemistry. YTR107-mediated radiosensitization was assessed in NSCLC cell lines and xenografts. Results: Use of NPM1-null MEFs demonstrated that NPM1 is critical for DNA double- strand break (DSB) repair, that loss of NPM1 increases radiation sensitivity, and that YTR107-mediated radiosensitization is NPM1 dependent. YTR107 was shown to inhibit NPM1 oligomerization and impair formation of pNPM1 irradiation-induced foci that colocalized with γH2AX foci. Analysis of the TMA demonstrated that NPM1 is overexpressed in subsets of NSCLC. YTR107 inhibited DNA DSB repair and radiosensitized NSCLC lines and xenografts. Conclusions: These data demonstrate that YTR107-mediated targeting of NPM1 impairs DNA DSB repair, an event that increases radiation sensitivity.

  6. UV- and gamma-radiation sensitive mutants of Arabidopsis thaliana

    International Nuclear Information System (INIS)

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

  7. Genetic and epigenetic features in radiation sensitivity. Part II: implications for clinical practice and radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Bourguignon, Michel H. [Direction Generale de la Surete Nucleaire et de la Radioprotection, Paris Cedex 12 (France); CEA-DSV-DRM Hopital, Service de Recherches en Hemato-Immunologie, Saint Louis, Paris (France); Gisone, Pablo A.; Perez, Maria R.; Michelin, Severino; Dubner, Diana; Giorgio, Marina di [Autoridad Regulatoria Nuclear, Laboratorio de Radiopatologia, Buenos Aires (Argentina); Carosella, Edgardo D. [CEA-DSV-DRM Hopital, Service de Recherches en Hemato-Immunologie, Saint Louis, Paris (France)

    2005-03-01

    Recent progress especially in the field of gene identification and expression has attracted greater attention to the genetic and epigenetic susceptibility to cancer, possibly enhanced by ionising radiation. This issue is especially important for radiation therapists since hypersensitive patients may suffer from adverse effects in normal tissues following standard radiation therapy, while normally sensitive patients could receive higher doses of radiation, offering a better likelihood of cure for malignant tumours. Although only a small percentage of individuals are ''hypersensitive'' to radiation effects, all medical specialists using ionising radiation should be aware of the aforementioned progress in medical knowledge. The present paper, the second of two parts, reviews human disorders known or strongly suspected to be associated with hypersensitivity to ionising radiation. The main tests capable of detecting such pathologies in advance are analysed, and ethical issues regarding genetic testing are considered. The implications for radiation protection of possible hypersensitivity to radiation in a part of the population are discussed, and some guidelines for nuclear medicine professionals are proposed. (orig.)

  8. Genetic and epigenetic features in radiation sensitivity. Part II: implications for clinical practice and radiation protection.

    Science.gov (United States)

    Bourguignon, Michel H; Gisone, Pablo A; Perez, Maria R; Michelin, Severino; Dubner, Diana; Giorgio, Marina Di; Carosella, Edgardo D

    2005-03-01

    Recent progress especially in the field of gene identification and expression has attracted greater attention to the genetic and epigenetic susceptibility to cancer, possibly enhanced by ionising radiation. This issue is especially important for radiation therapists since hypersensitive patients may suffer from adverse effects in normal tissues following standard radiation therapy, while normally sensitive patients could receive higher doses of radiation, offering a better likelihood of cure for malignant tumours. Although only a small percentage of individuals are "hypersensitive" to radiation effects, all medical specialists using ionising radiation should be aware of the aforementioned progress in medical knowledge. The present paper, the second of two parts, reviews human disorders known or strongly suspected to be associated with hypersensitivity to ionising radiation. The main tests capable of detecting such pathologies in advance are analysed, and ethical issues regarding genetic testing are considered. The implications for radiation protection of possible hypersensitivity to radiation in a part of the population are discussed, and some guidelines for nuclear medicine professionals are proposed. PMID:15692806

  9. Genetic and epigenetic features in radiation sensitivity. Part II: implications for clinical practice and radiation protection

    International Nuclear Information System (INIS)

    Recent progress especially in the field of gene identification and expression has attracted greater attention to the genetic and epigenetic susceptibility to cancer, possibly enhanced by ionising radiation. This issue is especially important for radiation therapists since hypersensitive patients may suffer from adverse effects in normal tissues following standard radiation therapy, while normally sensitive patients could receive higher doses of radiation, offering a better likelihood of cure for malignant tumours. Although only a small percentage of individuals are ''hypersensitive'' to radiation effects, all medical specialists using ionising radiation should be aware of the aforementioned progress in medical knowledge. The present paper, the second of two parts, reviews human disorders known or strongly suspected to be associated with hypersensitivity to ionising radiation. The main tests capable of detecting such pathologies in advance are analysed, and ethical issues regarding genetic testing are considered. The implications for radiation protection of possible hypersensitivity to radiation in a part of the population are discussed, and some guidelines for nuclear medicine professionals are proposed. (orig.)

  10. p53-Mediated apoptosis is the primary cause of radiation sensitivity in ataxia-telangiectasia

    International Nuclear Information System (INIS)

    The autosomal recessive disease ataxia-telangiectasia (A-T) is characterized by ataxia, immune defects, genetic instability and cancer. A cardinal feature of A-T is a marked sensitivity to the killing effects of ionizing radiation. However, repair of DNA damage in A-T cells is grossly normal and the cause of the radiation sensitivity has remained puzzling despite numerous investigations. We now report that p53-mediated apoptosis is primarily responsible for the radiation sensitivity of A-T cells. We exposed representing three different complementation groups as well as two control cell lines to 0, 1.5 and 3 Gy of 250 kv X-radiation. Morphologic changes, the appearance of cells with sub-G1 DNA content and presence of nucleosome ladders in genomic DNA were considered evidence of apoptosis. By all three criteria, apoptosis was detectable in the A-T cells 24-48 hours after irradiation, peaking by 72 hours. In contrast, control cells underwent minimal apoptosis. Similar results were obtained with 24 hours' exposure to 0.25-0.5 ng/ml streptonigrin, a radiomimetic mutagen. Disruption of p53 function in an A-T fibroblast line by transfection of either the dominant-negative p53143ala mutant or an HPV18 E6 gene was associated with acquisition of near-normal drug resistance and radiation-resistance, while transfection and expression of the p53143ala mutant did not affect the streptonigrin sensitivity of a control fibroblast line. Our results support our hypothesis that an unusually low threshold for the activation of p53-mediated apoptosis by DNA damage may be the primary etiology for both in vivo and in vitro mutagen-sensitivity in A-T. These data also suggest an etiology for the neurological deterioration and immune defects seen in A-T patients: inappropriate activation of apoptosis by spontaneous DNA damage

  11. Position sensitive detection of neutrons in high radiation background field

    International Nuclear Information System (INIS)

    We present the development of a high-resolution position sensitive device for detection of slow neutrons in the environment of extremely high γ and e− radiation background. We make use of a planar silicon pixelated (pixel size: 55 × 55 μm2) spectroscopic Timepix detector adapted for neutron detection utilizing very thin 10B converter placed onto detector surface. We demonstrate that electromagnetic radiation background can be discriminated from the neutron signal utilizing the fact that each particle type produces characteristic ionization tracks in the pixelated detector. Particular tracks can be distinguished by their 2D shape (in the detector plane) and spectroscopic response using single event analysis. A Cd sheet served as thermal neutron stopper as well as intensive source of gamma rays and energetic electrons. Highly efficient discrimination was successful even at very low neutron to electromagnetic background ratio about 10−4

  12. SENSITIVITY OF THE CUMIN SEEDS ASSOCIATED FUNGI TO GAMMA RADIATION

    International Nuclear Information System (INIS)

    The present study was carried out to investigate the sensitivity of fungi associated to cumin seeds for gamma radiation. In this regard, the isolated seed associated fungi from the cumin seeds were fifteen fungal species belonging to five genera. The fungal species concerning, Aspergillus ochraceus, Fusarium oxysporium and Aspergillus flavus were the predominant fungi in percentages of 17.8, 15.83 and 12.78 %, respectively. Aspergillus ochraceus was the most effective prevalent fungi on the seed germination causing highest percentage of seed invasion followed by Fusarium oxysporium and Aspergillus flavus. The amylolytic, proteolytic and lipolytic activity and mycotoxin production of the three predominant fungi were negatively influenced by gamma radiation when exposed to doses of 1.0 , 1.5 , 2.5 , 3.5 , 5.0 and 7.5 kGy a behaviour which was parallel to the inhibition in the amount of growth by gamma irradiation

  13. Sensitization of radiation-induced cell death by genistein

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Rim; Kim, In Gyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-03-15

    A number of epidemiological studies as well as biological experiments, showed that genistein, one of the isoflavone, prevents prostate cancer occurrence. In this study, we showed that genistein inhibited the cell proliferation of human promyeoltic leukemia HL-60 cells and induced G2/M phase arrest. In addition, combination of genistein treatment and {gamma}-irradiation displayed synergistic effect in apoptotic cell death of HL-60 cells. This means that the repair of genistein-induced DNA damage was hindered by {gamma}-irradiation and thus cell death was increased. In conclusion, genistein is one of the important chemicals that sensitize radiation-induced cell death.

  14. Position sensitive detection of neutrons in high radiation background field

    Czech Academy of Sciences Publication Activity Database

    Vavřík, Daniel; Jakůbek, Jan; Vacík, Jiří; Pospíšil, S.

    2014-01-01

    Roč. 85, č. 1 (2014), s. 013304. ISSN 0034-6748 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0060; GA ČR(CZ) GBP108/12/G108; GA TA ČR(CZ) TA01010237 Institutional support: RVO:68378297 ; RVO:61389005 Keywords : neutrons * pattern recognition * position sensitive detectors * radiation detectors * silicon detectors Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering; BG - Nuclear, Atomic and Molecular Physics, Colliders (UJF-V) Impact factor: 1.614, year: 2014 http://scitation.aip.org/content/aip/journal/rsi/85/1/10.1063/1.4862478

  15. Sensitivity analysis on parameters and processes affecting vapor intrusion risk

    KAUST Repository

    Picone, Sara

    2012-03-30

    A one-dimensional numerical model was developed and used to identify the key processes controlling vapor intrusion risks by means of a sensitivity analysis. The model simulates the fate of a dissolved volatile organic compound present below the ventilated crawl space of a house. In contrast to the vast majority of previous studies, this model accounts for vertical variation of soil water saturation and includes aerobic biodegradation. The attenuation factor (ratio between concentration in the crawl space and source concentration) and the characteristic time to approach maximum concentrations were calculated and compared for a variety of scenarios. These concepts allow an understanding of controlling mechanisms and aid in the identification of critical parameters to be collected for field situations. The relative distance of the source to the nearest gas-filled pores of the unsaturated zone is the most critical parameter because diffusive contaminant transport is significantly slower in water-filled pores than in gas-filled pores. Therefore, attenuation factors decrease and characteristic times increase with increasing relative distance of the contaminant dissolved source to the nearest gas diffusion front. Aerobic biodegradation may decrease the attenuation factor by up to three orders of magnitude. Moreover, the occurrence of water table oscillations is of importance. Dynamic processes leading to a retreating water table increase the attenuation factor by two orders of magnitude because of the enhanced gas phase diffusion. © 2012 SETAC.

  16. The sensitivity of human mesenchymal stem cells to ionizing radiation

    International Nuclear Information System (INIS)

    Purpose: Recent studies have shown that mesenchymal stem cells (MSCs) obtained from bone marrow transplantation patients originate from the host. This clinical observation suggests that MSCs in their niches could be resistant to irradiation. However, the biologic responses of bone marrow MSCs to irradiation have rarely been described in the literature. Methods and Materials: In this study, human bone marrow-derived, clonally expanded MSCs were used to investigate their sensitivity to irradiation in vitro, and the cellular mechanisms that may facilitate resistance to irradiation. The human lung cancer cell line A549 and the breast cancer cell line HCC1937 were used as controls for radiosensitivity; the former line has been shown to be radioresistant and the latter radiosensitive. We then examined their in vitro biologic changes and sensitivities to radiation therapy. Results: Our results suggest that MSCs are characterized as resistant to irradiation. Several cellular mechanisms were demonstrated that may facilitate resistance to irradiation: ATM protein phosphorylation, activation of cell-cycle checkpoints, double-strand break repair by homologous recombination and nonhomologous end joining (NHEJ), and the antioxidant capacity for scavenging reactive oxygen species. Conclusions: As demonstrated, MSCs possess a better antioxidant reactive oxygen species-scavenging capacity and active double-strand break repair to facilitate their radioresistance. These findings provide a better understanding of radiation-induced biologic responses in MSCs and may lead to the development of better strategies for stem cell treatment and cancer therapy

  17. Responses of cells to radiation sensitizers: methods of analysis

    International Nuclear Information System (INIS)

    Several well-known transforms of the widely-used Michaelis-Menten function linearize the kinetics of many competition reactions such as enzymatic processes. These transforms allow easy and accurate evaluation of the mathematical constants of the system, as well as giving clues to the various mechanisms involved in these competitions. Linearization techniques are applied to several sets of data from several authors that describe the radiation sensitivity determined by varied concentrations of two sensitizers - O2 and misonidazole. It is shown that, when the increment in sensitivity determined at the various concentrations of sensitizer is used as the dependent variable, straight lines are obtained from various sets of data when either the so-called Lineweaver-Burk or the Eadie-Hofstee transform is used. The E-H transform results in a better distribution of data points and, accordingly, is preferred. The transform allows recognition of two oxygen-dependent processes (one at low [O2] and one at high [O2]) in data apparently demonstrating but one; and, as well, two processes determined at two levels of misonidazole from data that appeared to describe one. These results support the evidence given earlier for two oxygen effects in other cells. Also, the transform reveals that in different cell systems two inhibitors of the oxygen effect appear to act in the same manner on one oxygen effect and in a different way on the other. The value of the transform in analysing mechanisms of sensitization is examined, and its further potential use in understanding the action of chemical protective agents pointed out. (author)

  18. Radiogenic male breast cancer with in vitro sensitivity to ionizing radiation and bleomycin

    International Nuclear Information System (INIS)

    A cytogenetically normal man with gynecomastia and a family history of diverse cancers developed adenocarcinoma of the breast 30 years following thymic irradiation. In vitro experiments measuring colony-forming ability of cultured skin fibroblasts from family members implied that the patient had a small but significant increase in sensitivity to ionizing radiation, and a moderate increase in sensitivity to bleomycin, a radiomimetic drug. Enhanced radiosensitivity of fibroblasts from the patient's mother, and bleomycin sensitivity of fibroblasts from the sister suggested, but did not prove, that genetic susceptibility affected the risk of radiogenic cancer in this individual. In vitro studies of cancer-prone kindreds are a useful research strategy in delineating mechanisms of carcinogenesis

  19. Advances in radiation biology: Relative radiation sensitivities of human organ systems. Volume 12

    Energy Technology Data Exchange (ETDEWEB)

    Lett, J.T.; Altman, K.I.; Ehmann, U.K.; Cox, A.B.

    1987-01-01

    This volume is a thematically focused issue of Advances in Radiation Biology. The topic surveyed is relative radiosensitivity of human organ systems. Topics considered include relative radiosensitivities of the thymus, spleen, and lymphohemopoietic systems; relative radiosensitivities of the small and large intestine; relative rediosensitivities of the oral cavity, larynx, pharynx, and esophagus; relative radiation sensitivity of the integumentary system; dose response of the epidermal; microvascular, and dermal populations; relative radiosensitivity of the human lung; relative radiosensitivity of fetal tissues; and tolerance of the central and peripheral nervous system to therapeutic irradiation.

  20. Advances in radiation biology: Relative radiation sensitivities of human organ systems. Volume 12

    International Nuclear Information System (INIS)

    This volume is a thematically focused issue of Advances in Radiation Biology. The topic surveyed is relative radiosensitivity of human organ systems. Topics considered include relative radiosensitivities of the thymus, spleen, and lymphohemopoietic systems; relative radiosensitivities of the small and large intestine; relative rediosensitivities of the oral cavity, larynx, pharynx, and esophagus; relative radiation sensitivity of the integumentary system; dose response of the epidermal; microvascular, and dermal populations; relative radiosensitivity of the human lung; relative radiosensitivity of fetal tissues; and tolerance of the central and peripheral nervous system to therapeutic irradiation

  1. Micronuclei: sensitivity for the detection of radiation induced damage

    International Nuclear Information System (INIS)

    The in vitro cytokinesis-block (CB) micronucleus (MN) assay for human peripheral blood has been used extensively for the assessment of chromosomal damage induced by ionizing radiation and chemicals and considered a suitable biological dosimeter for estimating in vivo whole body exposures, particularly in the case of large scale radiation accidents. One of the major drawbacks of the MN assay is its reduced sensitivity for the detection of damage induced by low doses of low LET radiation, due to the high variability among the spontaneous MN frequencies. It is suggested that age, smoking habit and sex are the main confounding factors that contribute to the observed variability. Previous work in our laboratory, shows a significant positive correlation of the spontaneous and radiation induced MN frequencies with age and smoking habit, the latter being the strongest confounder. These findings led to in vitro studies of the dose-response relationships for smoking and non smoking donors evaluated separately, using 60Co γ rays. The objectives of the present work are: 1-To increase the amount of data of the dose-response relationships, using γ rays from a 60Co source, for smoking and non smoking donors, in order to find, if applicable, a correction factor for the calibration curve that takes into account the smoking habit of the individual in the case of accidental overexposure dose assessment, particularly in the low dose range. 2-To establish general conclusions on the current state of the technique. The sample for smoking and non smoking calibration curves was enlarged in the range of 0Gy to 2Gy. The fitting of both curves, performed up to the 2Gy dose, resulted in a linear quadratic model. MN distribution among bi nucleated cells was found to be over dispersed with respect to Poisson distribution, the average ratio of variance to mean being 1.13 for non smokers and 1.17 for smokers. Each fitted calibration curve, for smoking and non smoking donors, fell within the 95

  2. Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution

    Science.gov (United States)

    Strada, S.; Unger, N.

    2015-09-01

    A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (all anthropogenic, biomass burning and non-biomass burning) are investigated by performing sensitivity experiments. On the global scale, our results show that land carbon fluxes (GPP and isoprene emission) are not sensitive to pollution aerosols, even under a global decline in surface solar radiation (direct + diffuse) by ~ 9 %. At the regional scale, plant productivity (GPP) and isoprene emission show a robust but opposite sensitivity to pollution aerosols, in regions where complex canopies dominate. In eastern North America and Europe, anthropogenic pollution aerosols (mainly from non-biomass burning sources) enhance GPP by +8-12 % on an annual average, with a stronger increase during the growing season (> 12 %). In the Amazon basin and central Africa, biomass burning aerosols increase GPP by +2-5 % on an annual average, with a peak in the Amazon basin during the dry-fire season (+5-8 %). In Europe and China, anthropogenic pollution aerosols drive a decrease in isoprene emission of -2 to -12 % on the annual average. Anthropogenic aerosols affect land carbon fluxes via different mechanisms and we suggest that the dominant mechanism varies across regions: (1) light scattering dominates in the eastern US; (2) cooling in the Amazon basin; and (3) reduction in direct radiation in Europe and China.

  3. Studies on radiation-sensitive nonsilver halide materials, (1)

    International Nuclear Information System (INIS)

    In order to discover new radiation-sensitive nonsilver halide materials, the coloration based on the formation of Stenhouse salts was studied in the following three systems: (a) furfural-amine/HCl aq/methanol solution, (b) furfural-amine/polyhalogenide/PMMA matrix, (c) furfural-amine/PVC matrix. Firstly, forty-five aromatic amines were surveyed to find out the amines suitable for the color precursors (reactant from furfural and amine) in the system (a). As a result, the five amines, which gave the precursors in good yields by the reaction with furfural, were selected: m-nitroaniline, N-methylaniline, m-methyl-N-methylaniline, aniline, and o-methoxyaniline. Secondly, the coloration induced by electron beam bombardment was studied in the systems (b) and (c) containing the color precursors (the reactants from these amines and furfural). Although the PMMA films containing the color precursors and polyhalogenides were sensitive to electron beam, they were not stable when standing under daylight at room temperature. The PVC films containing the color precursors were very stable and colored to reddish yellow (lambda sub(max) 498 - 545 nm) by electron beam bombardment. The PVC film containing N-methylaniline-furfural was the most sensitive and the increase in absorbance at 498 nm was 0.78 by electron beam bombardment of 60 kV - 7.5 x 10-7C/cm2. A good linear relationship existed between the degree of coloration and the amounts of electron beam bombardment in the range from 0 to 10-6C/cm2. (author)

  4. Regulation of early and delayed radiation responses in rat small intestine by capsaicin-sensitive nerves

    International Nuclear Information System (INIS)

    Purpose: Mast cells protect against the early manifestations of intestinal radiation toxicity, but promote chronic intestinal wall fibrosis. Intestinal sensory nerves are closely associated with mast cells, both anatomically and functionally, and serve an important role in the regulation of mucosal homeostasis. This study examined the effect of sensory nerve ablation on the intestinal radiation response in an established rat model. Methods and Materials: Rats underwent sensory nerve ablation with capsaicin or sham ablation. Two weeks later, a localized segment of ileum was X-irradiated or sham irradiated. Structural, cellular, and molecular changes were examined 2 weeks (early injury) and 26 weeks (chronic injury) after irradiation. The mast cell dependence of the effect of sensory nerve ablation on intestinal radiation injury was assessed using c-kit mutant (Ws/Ws) mast cell-deficient rats. Results: Capsaicin treatment caused a baseline reduction in mucosal mast cell density, crypt cell proliferation, and expression of substance P and calcitonin gene-related peptide, two neuropeptides released by sensory neurons. Sensory nerve ablation strikingly exacerbated early intestinal radiation toxicity (loss of mucosal surface area, inflammation, intestinal wall thickening), but attenuated the development of chronic intestinal radiation fibrosis (collagen I accumulation and transforming growth factor β immunoreactivity). In mast cell-deficient rats, capsaicin treatment exacerbated postradiation epithelial injury (loss of mucosal surface area), but none of the other aspects of radiation injury were affected by capsaicin treatment. Conclusions: Ablation of capsaicin-sensitive enteric neurons exacerbates early intestinal radiation toxicity, but attenuates development of chronic fibroproliferative changes. The effect of capsaicin treatment on the intestinal radiation response is partly mast cell dependent

  5. Effect of pre-existing thermal sensitization on the radiation induced sensitization in type 304 stainless steels

    International Nuclear Information System (INIS)

    It is generally recognized that radiation induced sensitization plays an important role in initiating irradiation assisted stress corrosion cracking (IASCC) of austenitic stainless steels in reactor core internal of light water reactor. However, the synergism between radiation sensitization and prior thermal sensitization is unclear. This situation is likely to occur in most welded core internal structures subjected to neutron irradiation. In this study, the effect of prior thermal treatment on radiation sensitization were investigated on proton irradiated Type 304 stainless steel (SS) of initially as-received (AR) and thermal-sensitized (SEN) conditions. The Cr depletion profiles were measured by field emission gun transmission electron microscopy/energy dispersive spectroscopy (FEGTEM/EDS), and were calculated by a radiation induced segregation (RIS) model. The different initial conditions were input in the RIS model calculations. For the as-received condition, the initial Cr profile was modeled by a uniform concentration distribution. For the initially thermal-sensitized condition, the wider Cr depletion profile measured by FEGTEM/EDS was input as the initial condition. The results showed that radiation sensitization is characterized by a very narrow Cr depleted zone. The Cr content at grain boundary tends to be lower as radiation dose increases. Comparing with the non-sensitized (as-received) specimens with the same dosage, the grain boundary Cr content without prior sensitization is higher than that with sensitization pre-treatment. The deeper grain boundary Cr concentration of irradiated thermally sensitized sample is induced not only from proton irradiation effect, but also resulted from pre-existing Cr depletion

  6. Biochemical reasoning for radiation protection and screening methods for radiation sensitivity and potential carcinogenicity

    International Nuclear Information System (INIS)

    Cells of different genetic characteristics respond differently to agents that modify radiation effects. When the modification is a result of chemical repair, reduction of the amount of damage by radical scavenging, production of hypoxia, or any other such mechanism, then the modification of the response will be the same for all types of cells, but not the same when biological or biochemical parameters are involved, because the differences between the cells affect the final outcome, and the genetic traits obviously become affected by chemical modifying agents. Some of these agents directly affect the repair of deoxyribonucleic acid (DNA) by mechanisms not yet understood. Another agent nicotinamide (NA), is directly linked to a repair pathway. Thus, a system that uses NA as a precursor of nicotinamide adenine dinucleotide (NAD)+, and uses NAD+ to produce the polymer polyadenosine diphosphate ribose (PADPR) appears to be an interesting and important factor in the biochemical events that may be linked to improved radioprotection. (author). 36 refs., 5 figs

  7. Temperature and hydration effects on absorbance spectra and radiation sensitivity of a radiochromic medium

    International Nuclear Information System (INIS)

    The effects of temperature on real time changes in optical density (ΔOD) of GAFCHROMIC EBT film were investigated. The spectral peak of maximum change in absorbance (λmax) was shown to downshift linearly when the temperature of the film was increased from 22 to 38 degree sign C. The ΔOD values were also shown to decrease linearly with temperature, and this decrease could not be attributed to the shift in λmax. A compensation scheme using λmax and a temperature-dependent correction factor was investigated, but provided limited improvement. Part of the reason may be the fluctuations in hydration of the active component, which were found to affect both position of absorbance peaks and the sensitivity of the film. To test the effect of hydration, laminated and unlaminated films were desiccated. This shifted both the major and minor absorbance peaks in the opposite direction to the change observed with temperature. The desiccated film also exhibited reduced sensitivity to ionizing radiation. Rehydration of the desiccated films did not reverse the effects, but rather gave rise to another form of the polymer with absorbance maxima upshifted further 20 nm. Hence, the spectral characteristics and sensitivity of the film can be dependent on its history, potentially complicating both real-time and conventional radiation dosimetry.

  8. Radiation sensitivity of memory chip module of an ID card

    Energy Technology Data Exchange (ETDEWEB)

    Mathur, V.K. [Naval Surface Warfare Center, Carderock Division, Bethesda MD 20817 (United States)]. E-mail: veerendra.mathur@navy.mil; Barkyoumb, J.H. [Naval Surface Warfare Center, Carderock Division, Bethesda MD 20817 (United States); Yukihara, E.G. [Department of Physics, Oklahoma State University, Stillwater, OK 74078 (United States); Goeksu, H.Y. [GSF- National Research Center for Environment and Health, D-85764 Neuherberg (Germany)

    2007-01-15

    The utility of ID card chip modules to function as a radiation dosimeter is investigated. Specifically the thermoluminescence (TL) and optically stimulated luminescence (OSL) of a sampling of chip modules are measured over the range of 0.4-12Gy. Both infrared (830nm) from a laser diode and blue light (470nm) from LEDs were used to perform the OSL measurements. The TL measurements showed a linear dose-response relationship, but the TL suffered from a large zero-dose signal in the unirradiated samples and dose regeneration with time after heating the chip modules. The OSL measurements also showed a linear dose-response, but did not exhibit a zero-dose signal or regeneration. Performing the infrared OSL measurements at a temperature of 140{sup -}bar C may improve the dose sensitivity to 0.15Gy, but the dose-response is supralinear in the dose range investigated. Curve fitting of infrared and blue stimulated luminescence curves showed that both exhibit a fast and a slow component. Thermal stability studies indicates the presence of a component that decays in the first hour of irradiation, and a component that is stable at least during the period of investigation (up to 10h). This stable component is more appropriate for dosimetry purposes.

  9. Radiation accidents affecting the eye and their treatment

    International Nuclear Information System (INIS)

    Eye injuries which can occur as a result of radiation accidents or leaks in nuclear power plants are described and their treatment discussed. The trauma may be due to mechanical or thermal influences or the result of exposure to chemicals or radioactivity. After stopping the bepharospasm careful inspection of the conjunctiva is mandatory. If the bulbus is intact, rinsing with a pulsating water jet (Waterpik) is recommended, while if it is perforated primary operative treatment of the injury must be performed before radiation demages sets in. It is pointed out that the special medical centers for the treatment of radiation damage are equipped for ophthalmic surgery. (orig.)

  10. Perfectionism, personality, and affective experiences: New insights from revised Reinforcement Sensitivity Theory

    OpenAIRE

    Stoeber, Joachim; Philip J. Corr

    2015-01-01

    Previous studies have linked perfectionism to differences in reinforcement sensitivity, but findings have been mixed. The present study explored the relationships between three forms of perfectionism (self-oriented, other-oriented, socially prescribed) and components of the revised Reinforcement Sensitivity Theory of personality in relation to the experience of positive and negative affect. In a sample of 388 university students, we found consistent evidence of significant bivariate and semip...

  11. Studying the sensitivity of personnel neutron dosemeter PDM-303 to high-energy neutron radiation

    International Nuclear Information System (INIS)

    The sensitivity of the PDM-303 personnel neutron dosemeter to high-energy radiation behind the U-70 accelerator shield and neutron calibration fields of IHEP is investigated. It is found that this dosemeter has high sensitivity to high-energy neutrons. The fact requires introduction of correcting calibration coefficients in the case of its application in conditions of the U-70 accelerator radiation

  12. From Specificity to Sensitivity: Affective states modulate visual working memory for emotional expressive faces

    Directory of Open Access Journals (Sweden)

    Thomas eMaran

    2015-08-01

    Full Text Available Previous findings suggest that visual working memory preferentially remembers angry looking faces. However, the meaning of facial actions is construed in relation to context. To date, there are no studies investigating the role of perceiver-based context when processing emotional cues in visual working memory. To explore the influence of affective context on visual working memory for faces, we conducted two experiments using both a visual working memory task for emotionally expressive faces and a mood induction procedure. Affective context was manipulated by unpleasant (Experiment 1 and pleasant (Experiment 2 IAPS pictures in order to induce an affect high in motivational intensity (defensive or appetitive, respectively compared to a low arousal control condition. Results indicated specifically increased sensitivity of visual working memory for angry looking faces in the neutral condition. Enhanced visual working memory for angry faces was prevented by inducing affects of high motivational intensity. In both experiments, affective states led to a switch from specific enhancement of angry expressions in visual working memory to an equally sensitive representation of all emotional expressions. Our findings demonstrate that emotional expressions are of different behavioral relevance for the receiver depending on the affective context, supporting a functional organization of visual working memory along with flexible resource allocation. In visual working memory, stimulus processing adjusts to situational requirements and transitions from a specifically prioritizing default mode in predictable environments to a sensitive, hypervigilant mode in exposure to emotional events.

  13. Interleukin 1 beta initially sensitizes and subsequently protects murine intestinal stem cells exposed to photon radiation

    International Nuclear Information System (INIS)

    Interleukin 1 (IL-1) has been shown to prevent early bone marrow-related death following total-body irradiation, by protecting hematopoietic stem cells and speeding marrow repopulation. This study assesses the effect of IL-1 on the radiation response of the intestinal mucosal stem cell, a nonhematopoietic normal cell relevant to clinical radiation therapy. As observed with bone marrow, administration of human recombinant IL-1 beta (4 micrograms/kg) to C3H/Km mice 20 h prior to total-body irradiation modestly protected duodenal crypt cells. In contrast to bone marrow, IL-1 given 4 or 8 h before radiation sensitized intestinal crypt cells. IL-1 exposure did not substantially alter the slope of the crypt cell survival curve but did affect the shoulder: the X-ray survival curve was offset to the right by 1.01 +/- 0.06 Gy when IL-1 was given 20 h earlier and by 1.28 +/- 0.08 Gy to the left at the 4-h interval. Protection was greatest when IL-1 was administered 20 h before irradiation, but minimal effects persisted as long as 7 days after a single injection. The magnitude of radioprotection at 20 h or of radiosensitization at 4 h increased rapidly as IL-1 dose increased from 0 to 4 micrograms/kg. However, doses ranging from 10 to 100 micrograms/kg produced no further difference in radiation response. Animals treated with saline or IL-1 had similar core temperatures from 4 to 24 h after administration, suggesting that thermal changes were not responsible for either sensitization or protection. Mice irradiated 20 h after IL-1 had significantly greater crypt cell survival than saline-treated irradiated controls at all assay times, which ranged from 54 to 126 h following irradiation. The intervals to maximum crypt depopulation and initiation of repopulation were identical in both saline- and IL-1-treated groups

  14. Factors affecting differential sweet corn sensitivity to HPPD-inhibiting herbicides

    Science.gov (United States)

    Mutation of a cytochrome P450 (CYP) allele on the short arm of chromosome five affects sensitivity in sweet corn to mesotrione and tembotrione+isoxadifen applied POST. Hybrids that are homozygous for the functional allele (i.e. CYPCYP) are tolerant of both herbicides and rarely injured at registered...

  15. A Modular High Sensitive Radiation Detector for Homel and Security and Post Event Applications

    International Nuclear Information System (INIS)

    A modular, high sensitive radiation monitoring system designed for the homeland security radiological requirements and radiological post event applications is presented. The prevention of undocumented and potentially threatening shipment of radioactive and nuclear materials is a problem at seaports, border crossings, rail yards, airports and similar locations that requires the use of sensitive radiation detectors. Furthermore; radiological events such as the Fukushima nuclear incident emphasize the need for sensitive detector for monitoring food and commercial products

  16. Toward the elucidation of factors concerning the individual difference of radiation sensitivity, and the reduction of radiation risks

    International Nuclear Information System (INIS)

    This article describes studies aiming at the title subject and contains 2 topics of genetic and non-genetic factors modifying the radiation sensitivity. The ultimate purposes of those studies are the introduction of individual weighting factor to correct the individual differences of the sensitivity (IDS) and the practical control of the sensitivity-concerned factors, in the field of medical exposure. For genetic factors, described are studies on factors modifying the sensitivity at DNA repair and on the control of the sensitivity through the DNA repairing factors. The former, using cultured cells, aims at identifying protein (gene) of possible biomarker for IDS in non-homologous end-joining (NHEJ), an important mechanism in repairing the double strand break of DNA. Ku protein is found as the candidate. The latter has revealed that cells lacking Artemis, XRCC4 or MDC1 gene are highly sensitive, and are planning to suppress Artemis activity artificially, which may lead to the reduction of radiation cancer formation due to the death of highly sensitive cells. For non-genetic factors, described are studies on the life habits modifying the sensitivity, on the control of the sensitivity through the radiation-induced adaptive response and with steroid hormone. In the first, in mice treated with high-calorie diet and X-irradiation, a possible radiation response is suggested in the hepatic DNA-methylation and micro-RNA. Second, the combination of radiation adaptive response in the genome damage and restriction of diet ingestion is shown to lower the sensitivity of mice with use of C, Ne ion or X-ray irradiation. Third, in studies on the radiation-induced formation and condensation of breast cancer stem cells in the presence of progesterone, the hormone is found to produce micro-RNA molecules relating with the suppression of cellular senescence and repressed carcinogenesis with over-expression of apoptosis inhibitory molecules. (T.T.)

  17. Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties.

    Science.gov (United States)

    Madsen, Jakob Torp; Vogel, Stefan; Johansen, Jeanne Duus; Andersen, Klaus Ejner

    2011-06-01

    Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens in ethanolic liposomes have been reported to enhance allergenicity compared with the allergens in similar vehicles without liposomes. The present report includes data on more sensitization studies using the mouse local lymph node assay with three contact allergens encapsulated in different dermal drug-delivery systems: liposomes, ethosomes, and polycaprolactone particles. The results show that the drug-delivery systems are not sensitizers in themselves. Encapsulating the hydrophilic contact allergen potassium dichromate in all three drug-delivery systems did not affect the sensitizing capacity of potassium dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed for encapsulating isoeugenol in polycaprolactone (1100 ± 406) compared with a formulation in acetone:olive oil (4491 ± 819) and in liposomes (3668 ± 950). Further, the size of DNCB-loaded liposomes did not affect the sensitizing properties. These results suggest that modern dermal drug-delivery systems may in some cases magnify or decrease the sensitizing capacity of the encapsulated contact allergen. PMID:21198410

  18. Radiation sensitivity of graphene field effect transistors and other thin film architectures

    Science.gov (United States)

    Cazalas, Edward

    film by slowing-down of neutron capture reaction products. The objective of this dissertation is to develop, characterize, and optimize novel graphene-based and thin-film radiation detectors. The dissertation includes a review of relevant physics, comprehensive descriptions and discussions of the experimental campaigns that were conducted, computational simulations, and detailed analysis of certain processes occurring in graphene-based and thin-film radiation detectors that significantly affect their response characteristics. Experiments have been conducted to characterize the electrical properties of GFETs and their responsivity to radiation of different types, such as visible, ultraviolet, X-ray, and gamma-ray photons, and alpha particles. The nature of graphene hysteretic effects under operational conditions has been studied. Spatially dependent sensitivity of GFETs to irradiation has been experimentally investigated using both a focused laser beam and focused X-ray microbeam. A model has been developed that deterministically simulates the mechanisms of charge transport within the GFET substrate and explains the experimental finding that the effective area of the GFET significantly exceeds the size of graphene. Monte Carlo simulations were also carried out to examine the efficacy of thin-film radiation detectors based on 10B-enriched boron nitride and Gd2O3 for neutron detection.

  19. Antiangiogenic Agent Might Upgrade tumor Cell Sensitivity to Ionizing Radiation

    International Nuclear Information System (INIS)

    The understanding of the fundamental role of angiogenesis and metastasis in cancer growth has led to tremendous interest in research regarding its regulatory mechanisms and clinical implications in the management of cancer. The present study was conducted to evaluate the influence of the angiogenic regulators modification on the tumor growth and the cell sensitivity to ionizing radiation targeting the improvement of cancer therapeutic protocols. Accordingly, the antiangiogenic activity of apigenin and selenium was tested in vitro via MTT assay. The action of Apigenin and or Selenium was examined in vivo by using a model of solid tumor carcinoma (EAC). The growth rate of solid tumor in all experimental groups was measured by Caliper. The irradiated mice were exposed to 6.5 Gy of gamma rays. Apigenin 50 mg/kg body weight and selenium 5 μg per mice were daily administrated for 14 consecutive days after tumor volume reached 1mm3. The angiogenic activators TNF-α (key cytokine) in spleen, serum MMP 2 and MMP 9, liver and tumor NO, the lipid peroxidation (LPx) and angiogenic inhibitor TIMP-1 in spleen as well as, antioxidant markers (CAT, SOD, GPX) in tumor and liver tissue and DNA fragmentation in splenocytes were estimated to monitor efficacy of Apigenin and selenium in cancer treatment strategy. All parameters were determined as a time course on days 16 and 22 after tumor volume reached 1mm3. The using of MTT assay on EAC cells shows inhibition in EAC cell proliferation after the incubation with apigenin and /or selenium. The administration of apigenin and /or selenium to mice bearing tumor and to irradiated mice bearing tumor reduce significantly the TNF-α expression, MMP 2,9 , NO , LPx level and increased the antioxidant enzymes (GPx , SOD and CAT) activities. The DNA fragmentation and the antiangiogenic factors TIMP-1 were significantly increased when compared with their values in mice bearing tumor or in irradiated mice bearing tumor. From the results obtained

  20. Black Carbon Vertical Profiles Strongly Affect Its Radiative Forcing Uncertainty

    Science.gov (United States)

    Samset, B. H.; Myhre, G.; Schulz, M.; Balkanski, Y.; Bauer, S.; Berntsen, T. K.; Bian, H.; Bellouin, N.; Diehl, T.; Easter, R. C.; Ghan, S. J.; Iversen, T.; Kinne, S.; Kirkevag, A.; Lamarque, J.-F.; Lin, G.; Liu, X.; Penner, J. E.; Seland, O.; Skeie, R. B.; Stier, P.; Takemura, T.; Tsigaridis, K.; Zhang, K.

    2013-01-01

    The impact of black carbon (BC) aerosols on the global radiation balance is not well constrained. Here twelve global aerosol models are used to show that at least 20% of the present uncertainty in modeled BC direct radiative forcing (RF) is due to diversity in the simulated vertical profile of BC mass. Results are from phases 1 and 2 of the global aerosol model intercomparison project (AeroCom). Additionally, a significant fraction of the variability is shown to come from high altitudes, as, globally, more than 40% of the total BC RF is exerted above 5 km. BC emission regions and areas with transported BC are found to have differing characteristics. These insights into the importance of the vertical profile of BC lead us to suggest that observational studies are needed to better characterize the global distribution of BC, including in the upper troposphere.

  1. Black Carbon Vertical Profiles Strongly Affect its Radiative Forcing Uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Samset, B. H.; Myhre, G.; Schulz, M.; Balkanski, Y.; Bauer, Susanne E.; Berntsen, T.; Bian, Huisheng; Bellouin, N.; Diehl, T.; Easter, Richard C.; Ghan, Steven J.; Iversen, T.; Kinne, Stefan; Kirkevag, A.; Lamarque, J.-F.; Lin, G.; Liu, Xiaohong; Penner, Joyce E.; Seland, O.; Skeie, R. B.; Stier, P.; Takemura, T.; Tsigaridis, K.; Zhang, Kai

    2013-03-01

    The impact of black carbon (BC) aerosols on the global radiation balance is not well constrained. Here twelve global aerosol models are used to show that at least 20% of the present uncertainty in modeled BC direct radiative forcing (RF) is due to diversity in the simulated vertical profile of BC mass. Results are from phases 1 and 2 of the global aerosol model intercomparison project (AeroCom). Additionally, a significant fraction of the variability is shown to come from high altitudes, as, globally, more than 40% of the total BC RF is exerted above 5 km. BC emission regions and areas with transported BC are found to have differing characteristics. These insights into the importance of the vertical profile of BC lead us to suggest that observational studies are needed to better characterize the global distribution of BC, including in the upper troposphere.

  2. Some factors affecting radiative heat transport in PWR cores

    International Nuclear Information System (INIS)

    This report discusses radiative heat transport in Pressurized Water Reactor cores, using simple models to illustrate basic features of the transport process. Heat transport by conduction and convection is ignored in order to focus attention on the restrictions on radiative heat transport imposed by the geometry of the heat emitting and absorbing structures. The importance of the spacing of the emitting and absorbing structures is emphasised. Steady state temperature distributions are found for models of cores which are uniformly heated by fission product decay. In all of the models, a steady state temperature distribution can only be obtained if the central core temperature is in excess of the melting point of UO2. It has recently been reported that the MIMAS computer code, which takes into account radiative heat transport, has been used to model the heat-up of the Three Mile Island-2 reactor core, and the computations indicate that the core could not have reached the melting point of UO2 at any time or any place. We discuss this result in the light of the calculations presented in this paper. It appears that the predicted stabilisation of the core temperatures at ∼ 22000C may be a consequence of the artificially large spacing between the radial rings employed in the MIMAS code, rather than a result of physical significance. (author)

  3. Individual radiation sensitivity (gender, age, genetic disposition). Consequences for radiation protection

    International Nuclear Information System (INIS)

    The effects of ionising radiation on human health is influenced by a number of physiological and molecular biological factors. This is also valid for the causation of stochastic radiation effects especially the causation of cancer. Several epidemiological studies have resulted with respect to the total rate of solid cancers that women are more sensitive than men by a factor of 1.6 to 2.0. For leukaemia this is not the case. The largest studies come from the investigations on the survivors of the atomic bombs in Hiroshima and Nagasaki. But also studies on the population of the Techa River (Southeast Urals) yield such data. The analyses of single cancer localizations come to different results with respect to the dependence on the sex. Secondary cancers after radiotherapy for cancer treatment show also higher rates in women than in men. A similar situation is observed with respect to the dependence of cancer rate on age. The total rate of solid cancers is highest with children and decreases with increasing age. The effects are very different again with single cancer localizations. An especially strong age dependence was observed for thyroid cancer. Increasingly individuals have been found who are especially radiosensitive on the basis of their genetic disposition also with respect to the causation of cancer. Mechanisms and possibilities to trace these individuals are discussed. It is also discussed whether and to which extent these data should have consequences for the practical radiological protection. (orig.)

  4. How sensitive is Hawking radiation to superluminal dispersion relations?

    International Nuclear Information System (INIS)

    We discuss the Hawking radiation process in a collapse scenario with superluminal dispersion relations. Due to these superluminal modifications, the horizon effectively becomes frequency-dependent. At every moment of the collapse, a critical frequency can be calculated such that frequencies higher than this critical frequency do not couple to the collapsing geometry and hence do not see any horizon. We discuss three important consequences. First, the late-time radiation in general has a lower intensity than in the standard Hawking picture. Second, the thermal output spectrum depends on the surface gravity, thereby effectively exploring the physics inside the black hole. Third, the radiation dies off as time advances.

  5. Investigation of Radiation Affected High Temperature Superconductors - YBCO

    Science.gov (United States)

    Veterníková, J.; Chudý, M.; Slugeň, V.; Sojak, S.; Degmová, J.; Snopek, J.

    In this paper, high temperature superconductors are studied in terms of radiation stability, which is necessary for application in fusion reactors. Perspective superconducting materials based on YBCO (Perkovskite structure) were measured by positron annihilation lifetime spectroscopy. Measurements were performed for samples prior to and after fast neutron irradiation in TRIGA MARK II reactor in Vienna. The samples demonstrated accumulation of Cu-O di-vacancies due to the irradiation. Nevertheless, the structure showed regeneration during thermal treatment by defects recombination. Positron spectroscopy results were complemented with values of critical temperature, which also showed changes of superconducting properties after the irradiation and the annealing.

  6. Mutations induced by ultraviolet radiation affecting virulence in Puccinia striiformis

    International Nuclear Information System (INIS)

    Uredospores of parent culture, cy 29-1, were treated by ultraviolet radiation and mutations to virulent were tested on resistant wheat cultivars inoculated with treated spores. 7 mutant cultures virulent to the test cultivars were developed with estimated mutation rate 10~6~10~4. The virulence of mutant cultures was different from the all known races of stripe rust. Resistance segregation to mutant cultures was detected in two test cultivars. The results suggested that mutation was important mechanism of virulence variation operative in asexual population of rust fungi

  7. The sensitizing effect of acrylates on radiation vulcanization of natural rubber latex

    International Nuclear Information System (INIS)

    The sensitizing effect of acrylates on radiation vulcanization of natural rubber latex was studied. The results indicate that Gc value of crosslinking (Gc) will be higher at the same radiation dose when a sensitizer exists, and Gc value decreases with the increase of radiation dose (D) conforming to the formula Gc KD-α, where K and α are constants depending on sensitizers. The more sensitizers added, the greater the Gc value. However, the viscosity of the natural rubber latex also increases rapidly along with the increase of sensitizers added. Some sensitizers, such as TMPTA, can decrease the optimum dose from about 200 kGy to approximately 20 kGy according to our experiment. The tensile strength of the film can reach round 20 MPa. Other physical properties are comparable to those of unsensitized. (author)

  8. Differential sensitivity of Chironomus and human hemoglobin to gamma radiation.

    Science.gov (United States)

    Gaikwad, Pallavi S; Panicker, Lata; Mohole, Madhura; Sawant, Sangeeta; Mukhopadhyaya, Rita; Nath, Bimalendu B

    2016-08-01

    Chironomus ramosus is known to tolerate high doses of gamma radiation exposure. Larvae of this insect possess more than 95% of hemoglobin (Hb) in its circulatory hemolymph. This is a comparative study to see effect of gamma radiation on Hb of Chironomus and humans, two evolutionarily diverse organisms one having extracellular and the other intracellular Hb respectively. Stability and integrity of Chironomus and human Hb to gamma radiation was compared using biophysical techniques like Dynamic Light Scattering (DLS), UV-visible spectroscopy, fluorescence spectrometry and CD spectroscopy after exposure of whole larvae, larval hemolymph, human peripheral blood, purified Chironomus and human Hb. Sequence- and structure-based bioinformatics methods were used to analyze the sequence and structural similarities or differences in the heme pockets of respective Hbs. Resistivity of Chironomus Hb to gamma radiation is remarkably higher than human Hb. Human Hb exhibited loss of heme iron at a relatively low dose of gamma radiation exposure as compared to Chironomus Hb. Unlike human Hb, the heme pocket of Chironomus Hb is rich in aromatic amino acids. Higher hydophobicity around heme pocket confers stability of Chironomus Hb compared to human Hb. Previously reported gamma radiation tolerance of Chironomus can be largely attributed to its evolutionarily ancient form of extracellular Hb as evident from the present study. PMID:27237970

  9. Does concrete composition affect photoneutron production inside radiation therapy bunkers?

    International Nuclear Information System (INIS)

    Different types of concretes are used for bunker construction for radiation therapy. As neutron production occurs in high-energy photon beams, the purpose of this study was to investigate the effect of different concretes on photoneutron doses at an isocenter and maze entrance door. The 18-MV photon beam of a Varian 2100 C/D linear accelerator and a radiation therapy bunker were simulated using the MCNPX Monte Carlo code. Different commercially available concretes were used in photoneutron calculations for the simulated bunker. Higher neutron doses of the water phantom were seen for barytes and galena concretes, while there was no significant (less than 1%) difference between the neutron dose of the phantom for all other concretes. Also, the neutron fluence at the inner and outer maze entrance varied up to 36% depending on the concretes' atomic compositions. It can be concluded that application of high-density concretes in order to use limited space or for other purposes may cause higher neutron doses in the maze entrance door and consequently may impose stricter requirements for neutron shielding of maze entrance doors. (author)

  10. Palliative or curative treatment intent affects communication in radiation therapy consultations.

    NARCIS (Netherlands)

    Timmermans, L.; Maazen, R.W.M. van der; Leer, J.W.H.; Kraaimaat, F.W.

    2006-01-01

    OBJECTIVE: To assess whether communication in radiotherapy consultations is affected by palliative or curative treatment intent. SUBJECTS AND METHODS: The study involved 160 patients and 8 radiation oncologists. Eighty patients visited the radiation oncologist (RO) for palliative treatment and 80 fo

  11. Sensitivity of Hawking radiation to superluminal dispersion relations

    International Nuclear Information System (INIS)

    We analyze the Hawking radiation process due to collapsing configurations in the presence of superluminal modifications of the dispersion relation. With such superluminal dispersion relations, the horizon effectively becomes a frequency-dependent concept. In particular, at every moment of the collapse, there is a critical frequency above which no horizon is experienced. We show that, as a consequence, the late-time radiation suffers strong modifications, both quantitative and qualitative, compared to the standard Hawking picture. Concretely, we show that the radiation spectrum becomes dependent on the measuring time, on the surface gravities associated with different frequencies, and on the critical frequency. Even if the critical frequency is well above the Planck scale, important modifications still show up.

  12. Process for curing ionizing radiation-highly sensitive resin composition

    International Nuclear Information System (INIS)

    A process is described for curing a radiation curable composition consisting essentially of (a) an amide represented by the formula R,CONR2R3 and (b) an unsaturated polyester resin by irradiating the composition with an ionizing radiation. R1 is H, an alkyl groups having from 1 to 17 carbon atoms or an alkenyl groups having from 1 to 17 carbon atoms, and R2 and R3 are each -H, -CH3, or -CH2OH. R1 and R2 taken together represent alkylene having 2 to 5 carbon atoms

  13. Simulated performance of a position sensitive radiation detecting system (COCAE)

    CERN Document Server

    Karafasoulis, K; Seferlis, S; Kaissas, I; Lambropoulos, C; Loukas, D; Poritiriadis, C

    2011-01-01

    Extensive simulations of a portable radiation detecting system have been performed in order to explore important performance parameters. The instrument consists of a stack of ten detecting layers made of pixelated Cadmium Telluride (CdTe) crystals. Its aim is to localize and identify radiation sources, by exploiting the Compton imaging technique. In this paper we present performance parameters based on simulation studies. Specifically the ratio of incompletely absorbed photons, the detector's absolute efficiency as well as its energy and angular resolution are evaluated in a wide range of incident photon energies.

  14. Ultraviolet Radiation Sensitivity in Cave Bacteria: Evidence of Adaptation to the Subsurface?

    OpenAIRE

    Snider Jessica R.; Goin Caitlin; Miller Robert V.; Boston Penelope J.; Northup Diana E.

    2009-01-01

    We hypothesize that a reduced capacity to withstand or repair cellular damage from ultraviolet radiation may be present in caveadaptedmicroorganisms that never experience such conditions. However, a small number of previous studies have shown that somesubsurface bacteria do not show greater sensitivity to ultraviolet radiation (UVR) than surface bacteria. To estimate UVR sensitivity incave bacteria, bacterial isolates were collected from Carlsbad Cavern, New Mexico, U.S.A., and percent surviv...

  15. Factors affecting radiation injury after interstitial brachytherapy for brain tumors

    International Nuclear Information System (INIS)

    The effects of brachytherapy on normal brain tissue are not easily delineated in the clinical setting because of the presence of concurrent radiation-induced changes in the coexistent brain tumor. Sequential morphologic studies performed after the implantation of radioactive sources into the brains of experimental animals have provided a better understanding of the character and magnitude of the structural changes produced by interstitial irradiation on normal brain tissue. Furthermore, the clinical experience accumulated thus far provides not only relevant information, but also some guidelines for future treatment policies. In this paper, the authors summarize the experimental findings and review the pathologic and clinical features of brain injury caused by interstitial brachytherapy. A number of studies in the older literature examined the effects of radioisotopes such as radium-226 (38--43), radon-22 (44--46), gold-198 (29,47--50), tantalum-182 (29,51,52) yttrium-9- (50,53,54), and cobalt-60 (29,50,55). This review is restricted to low- and high-activity encapsulated iodine-125 (125I) and iridium-192 (192Ir), the isotopes that are most commonly used in current clinical practice

  16. Chemical protection and sensitization to ionizing radiation:molecular investigations

    International Nuclear Information System (INIS)

    Chemical radioprotection and radiosensitization are induced by the presence of certain chemical compounds, which reduce or enhance the effect of ionizing radiation on living organisms. Such substances are either naturally present or may be artificially introduced in the living cells. Chemical radioprotectors are interesting for possible application in the health protection of both professionally exposed workers and patients treated by radiation for diagnostic and thereapeutic purposes. Interest in chemical radiosensitization has increased recently because of its potential application in the radiotherapy of tumours. Both radioprotection and radiosensitization occur by means of complicated mechanisms, which at first correspond to very fast reactions. The mechanism of the interaction between such substances and radiation-induced biological radicals has been investigated by means of pulse radiolysis and rapid mixing techniques. Examples of the application of these techniques are given to illustrate how information has been obtained on the molecular basis of radiation chemical modi-fication at the cellular level. In particular some interactions between model systems of biological interest (DNA, DNA components, enzymes, amino acids, etc.) and sulphur-containing radioprotectors (glutathione, cysteine, etc.) and/or electroaffinic radiosensitizers, are described. (H.K.)

  17. A systemic administration of liposomal curcumin inhibits radiation pneumonitis and sensitizes lung carcinoma to radiation

    Directory of Open Access Journals (Sweden)

    Shi HS

    2012-05-01

    Full Text Available Hua-shan Shi1,* Xiang Gao,1,3,* Dan Li,1,* Qiong-wen Zhang,1 Yong-sheng Wang,2 Yu Zheng,1 Lu-Lu Cai,1 Ren-ming Zhong,2 Ao Rui,1 Zhi-yong Li,1 Hao Zheng,1 Xian-cheng Chen,1 Li-juan Chen,11State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, West China Medicine School, Sichuan University, Chengdu, Sichuan, People's Republic of China; 2State Key Laboratory of Biotherapy and Department of Thoracic Oncology, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan, People's Republic of China; 3Deparment of Pathophysiology, College of Preclinical and Forensic Medical Sciences, Sichuan University, Chengdu, People's Republic of China*These authors contributed equally to this workAbstract: Radiation pneumonitis (RP is an important dose-limiting toxicity during thoracic radiotherapy. Previous investigations have shown that curcumin is used for the treatment of inflammatory conditions and cancer, suggesting that curcumin may prevent RP and sensitize cancer cells to irradiation. However, the clinical advancement of curcumin is limited by its poor water solubility and low bioavailability after oral administration. Here, a water-soluble liposomal curcumin system was developed to investigate its prevention and sensitizing effects by an intravenous administration manner in mice models. The results showed that liposomal curcumin inhibited nuclear factor-κB pathway and downregulated inflammatory factors including tumor necrosis factor-α, interleukin (IL-6, IL-8, and transforming growth factor-β induced by thoracic irradiation. Furthermore, the combined treatment with liposomal curcumin and radiotherapy increased intratumoral apoptosis and microvessel responses to irradiation in vivo. The significantly enhanced inhibition of tumor growth also was observed in a murine lung carcinoma (LL/2 model. There were no obvious toxicities observed in mice. The current results indicate that liposomal curcumin can effectively

  18. Sensitivity to plant modelling uncertainties in optimal feedback control of sound radiation from a panel

    DEFF Research Database (Denmark)

    Mørkholt, Jakob

    1997-01-01

    Optimal feedback control of broadband sound radiation from a rectangular baffled panel has been investigated through computer simulations. Special emphasis has been put on the sensitivity of the optimal feedback control to uncertainties in the modelling of the system under control.A model of a...... rectangular baffled panel radiating into free field has been constructed. Secondary actuators have been modelled as vibrational inputs acting directly on the panel. A cost function proportional to the averaged radiated sound power and based on knowledge of the modal amplitudes of the panel has been derived in...... terms of a set of radiation filters modelling the radiation dynamics.Linear quadratic feedback control applied to the panel in order to minimise the radiated sound power has then been simulated. The sensitivity of the model based controller to modelling uncertainties when using feedback from actual and...

  19. Sensitivity study of cloud/radiation interaction using a second order turbulence radiative-convective model

    International Nuclear Information System (INIS)

    A high resolution one-dimensional version of a second order turbulence convective/radiative model, developed at the Los Alamos National Laboratory, was used to conduct a sensitivity study of a stratocumulus cloud deck, based on data taken at San Nicolas Island during the intensive field observation marine stratocumulus phase of the First International Satellite Cloud Climatology Program (ISCCP) Regional Experiment (FIRE IFO), conducted during July, 1987. Initial profiles for liquid water potential temperature, and total water mixing ratio were abstracted from the FIRE data. The dependence of the diurnal behavior in liquid water content, cloud top height, and cloud base height were examined for variations in subsidence rate, sea surface temperature, and initial inversion strength. The modelled diurnal variation in the column integrated liquid water agrees quite well with the observed data, for the case of low subsidence. The modelled diurnal behavior for the height of the cloud top and base show qualitative agreement with the FIRE data, although the overall height of the cloud layer is about 200 meters too high

  20. Surface microstructure and physicochemical properties of parchment affected by detergent and γ-radiation

    International Nuclear Information System (INIS)

    Surface microstructure relief and physical-chemical properties of modern and ancient parchment have been investigated when affected by detergent and γ-radiation. It is demonstrated that radiation of 10-25 kGr of ancient parchment is not followed by a change of its surface layer microstructure and relief, but deteriorates its physical-chemical properties. The detergent and its application in combination with γ-radiation of 5 kGr does not affect significantly the surface layer structure and relief of modern and ancient parchment

  1. Effect of low sensitizing radiation doses on immune state during mammary gland cancer radiotherapy

    International Nuclear Information System (INIS)

    Results of clinical application of preoperational radiotherapy of mammary gland cancer at low sensitizing radiation doses (0.1 Gr) before using the main single dose (1.9 Gr) for modification of tumor radiosensitivity and increase of efficiency of radiotherapy are presented. Small radiation doses are stated to promote decrease of the number of skin radiation reactions, conservation of blood and T-immunosystem parameters within the limits of physiologic oscillations

  2. Radiation-Sensitive Indicator Based on m-Cresol Purple Dyed Poly (vinyl Butyral) for Possible Use in Radiation Dosimetry

    International Nuclear Information System (INIS)

    In the present work a PVB films containing different concentrations of m-cresol purple (ph indicator) and chloral hydrate were prepared. The chlorine containing (chIoral hydrate) polymer was dehydrochlorinated when the material irradiated thereby reducing ph and causing the acid-sensitive dye to change color. Such materials are not, however, reported to be sensitive. and quantitative at relatively low radiation doses. The useful dose ranges of this film ranges between 2 and 6 kGy. Radiation chemical yield was calculated. The effects of temperature and relative humidity during irradiation as well as pre and post irradiation stability on the response of films were described

  3. Sensitivity of the vibrios to ultraviolet-radiation

    International Nuclear Information System (INIS)

    The ultraviolet-inactivation kinetics of a number of strains of Vibrio cholerae (classical), Vibrio cholerae (el tor), NAG vibrios and Vibrio parahaemolyticus were investigated. Statistical analyses revealed significant differences between any two of the four types of vibrio in respect of their sensitivity to U.V. (author)

  4. Radiation sensitivity of fungal microflora isolated from some pharmaceutical ingredients

    International Nuclear Information System (INIS)

    The total number of fungal microflora of D-glucose, NaCl, KCl and their solutions was determined. The fungal isolates were identified as Aspergillus fumigatus. Aspergillus niger; Spicaria divaricate and Spicaria silvatica and their response to γ-radiation was determined, the most predominant isolate Asp. fumigatus was also the most irradiation resistant. The Dio and the lethal dose were determined for each isolate in a pure spore suspension as well as in the presence of the other isolates. The higher lethal dose values obtained for pure spore suspension as compared to that obtained for the natural fungal flora a D-glucose are discussed in terms of spore clumping. The activity of amylase, protease and L-asparaginase of Asp. fumigatus was examined prior to and after exposure to different doses of γ-radiation. Though all were inhibited at high doses, the effect was not as drastic as it was on cell viability

  5. Studies on radiation-sensitive nonsilver halide materials, (2)

    International Nuclear Information System (INIS)

    Dye-precursors made from furfural and some aniline derivatives become red-colored upon irradiation with ionization radiatios in PVC matrix, forming Stenhouse salts with the HCl evolved from the matrix. The coloration of the precursor from N-methylaniline, having the most excellent potential for dosimetry among the precursors, was studied for the irradiation of electron beam (60 kV) and X-ray (50 - 240 kVp). The following conclusions were obtained for the electron beam bombardment. (1) The response range is 10-8 - 10-6 C/cm2 or 103 - 105 rad, where good linearity between coloration and charge density exists. (2) The highest sensitivity is obtained when the concentration of the precursor is >=5 wt% for the amount of PVC and the film thickness is >=32 μm. (3) Addition of 25 wt% of DOP enhances not only the sensitivity by ca. 20% but also the stability of the color from several days to several months. (4) The sensitivity is increased by ca. 15% when a conductive base is used for the film. (5) G value for the formation of the dye, i.e., that for the formation of HCl is 13.5 - 15.5. The followings were obtained for the irradiation of X-ray. (1) The response range is 103 - 105 R or rad. (2) The sensitivity for the absorbed dose is independent of the energy but is approximately proportional to the film thickness. (3) The sensitivity is higher than that for electrons by the factor of ca. 1.6, reflecting the higher G(HCl) value, 23 - 25. (author)

  6. Andrographolide Sensitizes Ras-Transformed Cells to Radiation in vitro and in vivo

    International Nuclear Information System (INIS)

    Purpose: Increasing the sensitivity of tumor cells to radiation is a major goal of radiotherapy. The present study investigated the radiosensitizing effects of andrographolide and examined the molecular mechanisms of andrographolide-mediated radiosensitization. Methods and Materials: An H-ras-transformed rat kidney epithelial (RK3E) cell line was used to measure the radiosensitizing effects of andrographolide in clonogenic assays, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide assays, and a xenograft tumor growth model. The mechanism of andrographolide-sensitized cell death was analyzed using annexin V staining, caspase 3 activity assays, and terminal transferase uridyl nick end labeling assays. The roles of nuclear factor kappa B (NF-κB) and Akt in andrographolide-mediated sensitization were examined using reporter assays, electrophoretic mobility shift assays, and Western blotting. Results: Concurrent andrographolide treatment (10 μM, 3 h) sensitized Ras-transformed cells to radiation in vitro (sensitizer enhancement ratio, 1.73). Andrographolide plus radiation (one dose of 300 mg/kg peritumor andrographolide and one dose of 6 Gy radiation) resulted in significant tumor growth delay (27 ± 2.5 days) compared with radiation alone (22 ± 1.5 days; p <.05). Radiation induced apoptotic markers (e.g., caspase-3, membrane reversion, DNA fragmentation), and andrographolide treatment did not promote radiation-induced apoptosis. However, the protein level of activated Akt was significantly reduced by andrographolide. NF-κB activity was elevated in irradiated Ras-transformed cells, and andrographolide treatment significantly reduced radiation-induced NF-κB activity. Conclusion: Andrographolide sensitized Ras-transformed cells to radiation both in vitro and in vivo. Andrographolide-mediated radiosensitization was associated with downregulation of Akt and NF-κB activity. These observations indicate that andrographolide is a novel radiosensitizing agent

  7. Construction and isolation of radiation sensitive mutants of Escherichia Coli

    International Nuclear Information System (INIS)

    Damage to DNA by ionizing radiation consists mainly of single (SSB) and double (DSB) strand breaks as well as several types of base alterations, all of which may be removed by different repair mechanisms. Radiation also induces the SOS response, a set of repair and/or damage tolerance genes involved in functions such as replication arrest, excision and recombination repair, increase of both spontaneous and induced mutation and prophage induction, among others. The degree of SOS induction is related to the type and amount of damage and may be easily determined by a simple colorimetric assay, the SOS chromo test. In order to investigate the role of protection and/or repair genes on bacterial radiosensitivity, E. coli strains defective in either oxyR, recJ or recO genes were constructed and their respective SOS response to radiation, duly examined. The results show that although lack of regulatory gene oxyR increases radiosensitivity, it is the deficiencies in recJ and recO which seem to be more important. Both genes appear to take part in the repair of DSB and according to SOS measurements, their role is related also to damage processing conducent to the SOS triggering signal. A hypothetical working mechanism for the purpose, partially supported by the data is proposed. (Author)

  8. Sensitivity of Escherichia coli acrA Mutants to Psoralen plus Near-Ultraviolet Radiation

    DEFF Research Database (Denmark)

    Hansen, M. Trier

    1982-01-01

    The sensitivity to psoralen plus near-ultraviolet radiation (PUVA) was compared in a pair of E. coli strains differing at the acrA locus. Survival was determined for both bacteria and phage λ. AcrA mutant cells were 40 times more sensitive than wild type to the lethal effect of PUVA. Free λ phage...

  9. Radiation effects in ultraviolet sensitive SiC photodiodes

    International Nuclear Information System (INIS)

    We tested SiC photodiodes with Co-60 gamma rays up to a total dose of 22 Mrad(SiC) and 32 MeV protons up to a fluence of 9 x 1012 cm-2. They showed a decrease in sensitivity of about 50% at a dose of 1 Mrad. The same decrease or somewhat less was observed during proton irradiations when the fluence is converted to an applied dose. (authors)

  10. Gimeracil sensitizes cells to radiation via inhibition of homologous recombination

    International Nuclear Information System (INIS)

    Background and purpose: 5-Chloro-2,4-dihydroxypyridine (Gimeracil) is a component of an oral fluoropyrimidine derivative S-1. Gimeracil is originally added to S-1 to yield prolonged 5-FU concentrations in tumor tissues by inhibiting dihydropyrimidine dehydrogenase, which degrades 5-FU. We found that Gimeracil by itself had the radiosensitizing effect. Methods and materials: We used various cell lines deficient in non-homologous end-joining (NHEJ) or homologous recombination (HR) as well as DLD-1 and HeLa in clonogenic assay. γ-H2AX focus formation and SCneo assay was performed to examine the effects of Gimeracil on DNA double strand break (DSB) repair mechanisms. Results: Results of γ-H2AX focus assay indicated that Gimeracil inhibited DNA DSB repair. It did not sensitize cells deficient in HR but sensitized those deficient in NHEJ. In SCneo assay, Gimeracil reduced the frequency of neo-positive clones. Additionally, it sensitized the cells in S-phase more than in G0/G1. Conclusions: Gimeracil inhibits HR. Because HR plays key roles in the repair of DSBH caused by radiotherapy, Gimeracil may enhance the efficacy of radiotherapy through the suppression of HR-mediated DNA repair pathways.

  11. Silver nanoparticles: a novel radiation sensitizer for glioma?

    Science.gov (United States)

    Liu, Peidang; Huang, Zhihai; Chen, Zhongwen; Xu, Ruizhi; Wu, Hao; Zang, Fengchao; Wang, Cailian; Gu, Ning

    2013-11-01

    Malignant gliomas are the most common primary intracranial tumors with a dismal prognosis. Previous investigations by our group demonstrated the radiosensitizing effect of silver nanoparticles (AgNPs) on glioma cells in vitro. The goal of the present study was to evaluate the efficacy of intratumoral administration of AgNPs in combination with a single dose of ionizing radiation at clinically relevant MV energies for the treatment of C6 glioma-bearing rats. AgNPs (10 or 20 μg/10 μl) were stereotactically administered on day 8 after tumor implantation. One day after AgNP injection, rats bearing glioma received 10 Gy radiation. The mean survival times were 100.5 and 98 days, the corresponding percent increase in life spans was 513.2% and 497.7%, and the cure rates were 41.7 and 38.5% at 200 days for the 10 and 20 μg AgNPs and radiation combination groups, respectively. In contrast, the mean survival times for irradiated controls, 10 and 20 μg AgNPs alone, and untreated controls were 24.5, 16.1, 19.4, and 16.4 days, respectively. Furthermore, a cooperative antiproliferative and proapoptotic effect was obtained when gliomas were treated with AgNPs followed by radiotherapy. Our results showed the therapeutic efficacy of AgNPs in combination with radiotherapy without apparent systemic toxicity, suggesting the clinical potential of AgNPs in improving the outcome of malignant glioma radiotherapy.Malignant gliomas are the most common primary intracranial tumors with a dismal prognosis. Previous investigations by our group demonstrated the radiosensitizing effect of silver nanoparticles (AgNPs) on glioma cells in vitro. The goal of the present study was to evaluate the efficacy of intratumoral administration of AgNPs in combination with a single dose of ionizing radiation at clinically relevant MV energies for the treatment of C6 glioma-bearing rats. AgNPs (10 or 20 μg/10 μl) were stereotactically administered on day 8 after tumor implantation. One day after Ag

  12. Uncertainty and Sensitivity Analysis of Afterbody Radiative Heating Predictions for Earth Entry

    Science.gov (United States)

    West, Thomas K., IV; Johnston, Christopher O.; Hosder, Serhat

    2016-01-01

    The objective of this work was to perform sensitivity analysis and uncertainty quantification for afterbody radiative heating predictions of Stardust capsule during Earth entry at peak afterbody radiation conditions. The radiation environment in the afterbody region poses significant challenges for accurate uncertainty quantification and sensitivity analysis due to the complexity of the flow physics, computational cost, and large number of un-certain variables. In this study, first a sparse collocation non-intrusive polynomial chaos approach along with global non-linear sensitivity analysis was used to identify the most significant uncertain variables and reduce the dimensions of the stochastic problem. Then, a total order stochastic expansion was constructed over only the important parameters for an efficient and accurate estimate of the uncertainty in radiation. Based on previous work, 388 uncertain parameters were considered in the radiation model, which came from the thermodynamics, flow field chemistry, and radiation modeling. The sensitivity analysis showed that only four of these variables contributed significantly to afterbody radiation uncertainty, accounting for almost 95% of the uncertainty. These included the electronic- impact excitation rate for N between level 2 and level 5 and rates of three chemical reactions in uencing N, N(+), O, and O(+) number densities in the flow field.

  13. Radiation Power Affected by Current and Wall Radius in Water Cooled Vortex Wall-stabilized Arc

    Science.gov (United States)

    Iwao, Toru; Nakamura, Takaya; Yanagi, Kentaro; Yamamoto, Shinji

    2015-11-01

    The arc lighting to obtain the environment to evacuate, save the life, keep the safety and be comfortable are focus on. The lack of radiation intensity and color rendering is problem because of inappropriate energy balance. Some researchers have researched the arc lamp mixed with metal vapor for improvement of color rendering spectrum. The metal vapor can emit the high intense radiation. In addition, the radiation is derived from the high temperature medium. Because the arc temperature can be controlled by current and arc radius, the radiation can be controlled by the current and arc radius. This research elucidates the radiation power affected by the current and wall radius in wall-stabilized arc of water-cooled vortex type. As a result, the radiation power increases with increasing the square of current / square of wall radius because of the temperature distribution which is derived from the current density at the simulation.

  14. Radiation and heat sensitivity of microflora in mixed spices

    International Nuclear Information System (INIS)

    Spices such as coriander, cumin, turmeric, chilli collected from local market were found to be highly contaminated with bacteria and fungi. A dose of 3 kGy without heat treatment reduced the microbial load from 6 log to 3 log and from 5 log to 2 log units depending on the storage temperature whereas the same dose of radiation combined with heat treatment reduced the microbial load from 6 log to 2 log units and from 4 log to below detectable level depending on storage condition. The combination treated spices retained good organoleptic quality in comparison to that of only irradiated species with higher dose. 11 refs., 2 tables (author)

  15. The multiple factors affecting the association between atopic dermatitis and contact sensitization

    DEFF Research Database (Denmark)

    Thyssen, J P; McFadden, J P; Kimber, I

    2014-01-01

    Atopic dermatitis and allergic contact dermatitis are both common skin diseases having an immune pathogenesis. There has been considerable interest about their inter-relationships with regard to altered susceptibility. Recent investigations have shed new light on this important question, and in...... this article, we explore whether there is evidence that atopic dermatitis affects the risk of contact sensitization and allergic contact dermatitis. The use of topical products to treat xerotic and inflamed skin in atopic dermatitis often results in a higher prevalence of sensitization to, for example......, fragrances and other ingredients in emollients. Moreover, the prevalence of metal allergy seems to be increased, probably due to compromised chelation of the metals in the stratum corneum of patients with atopic dermatitis. However, conversely, the T-helper cell 2 bias that characterizes immune responses in...

  16. Sensitization of Salmonella typhi towards gamma-radiation by ascorbic acid

    International Nuclear Information System (INIS)

    The sensitivity of a S. typhi culture to γ-radiation has been examined. The D10 value, when the culture was irradiated in phosphate buffer, was found to be 70 krad. The addition of ascorbic acid (at a concentration of 0.57 mM) during irradiation, sensitized this organism quite markedly towards γ-radiation. This was evident from the observation that the D10 value was reduced to 20 krad when cells were irradiated in the ascorbic acid. Ascorbic acid was converted to its oxidized form during the radiation process. Irradiation under nitrogen instead of air inhibited the sensitization afforded by ascorbic acid. The population of cells surviving after irradiation in the presence of ascorbic acid showed a higher activity of catalase than its buffer-irradiated counterpart. The implication of the role of hydrogen peroxide (one of the possible intermediates formed during the oxidation of ascorbic acid) in sensitization is discussed. (author)

  17. Sensitivity analysis of a global aerosol model to understand how parametric uncertainties affect model predictions

    Science.gov (United States)

    Lee, L. A.; Carslaw, K. S.; Pringle, K. J.

    2012-04-01

    Global aerosol contributions to radiative forcing (and hence climate change) are persistently subject to large uncertainty in successive Intergovernmental Panel on Climate Change (IPCC) reports (Schimel et al., 1996; Penner et al., 2001; Forster et al., 2007). As such more complex global aerosol models are being developed to simulate aerosol microphysics in the atmosphere. The uncertainty in global aerosol model estimates is currently estimated by measuring the diversity amongst different models (Textor et al., 2006, 2007; Meehl et al., 2007). The uncertainty at the process level due to the need to parameterise in such models is not yet understood and it is difficult to know whether the added model complexity comes at a cost of high model uncertainty. In this work the model uncertainty and its sources due to the uncertain parameters is quantified using variance-based sensitivity analysis. Due to the complexity of a global aerosol model we use Gaussian process emulation with a sufficient experimental design to make such as a sensitivity analysis possible. The global aerosol model used here is GLOMAP (Mann et al., 2010) and we quantify the sensitivity of numerous model outputs to 27 expertly elicited uncertain model parameters describing emissions and processes such as growth and removal of aerosol. Using the R package DiceKriging (Roustant et al., 2010) along with the package sensitivity (Pujol, 2008) it has been possible to produce monthly global maps of model sensitivity to the uncertain parameters over the year 2008. Global model outputs estimated by the emulator are shown to be consistent with previously published estimates (Spracklen et al. 2010, Mann et al. 2010) but now we have an associated measure of parameter uncertainty and its sources. It can be seen that globally some parameters have no effect on the model predictions and any further effort in their development may be unnecessary, although a structural error in the model might also be identified. The

  18. Intrinsic radiation sensitivity is conserved during immortalization and malignant transformation steps in carcinogenesis

    International Nuclear Information System (INIS)

    The authors examined the effect of malignant transformation on the intrinsic radiation sensitivity of epithelial cells. Normal human epidermal keratinocytes (HEK), keratinocytes immortalized by hybrid virus (Ad12-SV-40) and malignant keratinocytes transformed by chemical carcinogens or the Ki-MSV were tested with graded doses of ionizing radiation. Normal HEK cells (D/sub 0/ = 2.24 Gy) proved to be more resistant to radiation than normal human fibroblasts (D/sub 0/=1.45 Gy). Mean inactivation doses D bar ranged from 3.47 to 4.27 Gy confirming a radiation resistant phenotype. This resistance was conserved in immortalized HEK cells and in malignant HEK cells. These experiments suggest that radiation sensitivity is an intrinsic property inherited from the parent cell that may be independent of the steps associated with carcinogenesis

  19. Sensitive Detection of Cold Cesium Molecules by Radiative Feshbach Spectroscopy

    OpenAIRE

    Chin, Cheng; Kerman, Andrew J.; Vuletić, Vladan; Chu, Steven

    2002-01-01

    We observe the dynamic formation of $Cs_2$ molecules near Feshbach resonances in a cold sample of atomic cesium using an external probe beam. This method is 300 times more sensitive than previous atomic collision rate methods, and allows us to detect more than 20 weakly-coupled molecular states, with collisional formation cross sections as small as $\\sigma =3\\times 10^{-16}$cm$^2$. We propose a model to describe the atom-molecule coupling, and estimate that more than $2 \\times 10^5$ $Cs_2$ mo...

  20. Hydroxyurea as a radiation sensitizer in malignancies of the head and neck

    International Nuclear Information System (INIS)

    A prospective randomized trail was undertaken to assess the efficacy of hydroxyurea as a radiation sensitizer. Disease control rates achieved significance (p<0.01) values only at 2 and 3 months post-radiation. At the end of 2 years of follow-up there was no significant difference in the disease control rate between the control and the experimental group. The toxicity in the experimental group was acceptable. One patient had severe vomiting; 13% showed severe mucositis, 4.5% had erythema of the treatment area and 40% showed dry desquamation. There seems to be no added advantage of hydroxyurea and radiation over radiation alone. (author). 12 refs., 2 tabs

  1. Oyster radiation sensitivity; Sensibilidade de ostras a radiacao

    Energy Technology Data Exchange (ETDEWEB)

    Marchese, Sandra R.M. [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil); Mastro, Nelida L. del [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1996-07-01

    Various food products like oysters, crabs and shrimps have been described as possible Vibrio spp. transmitting agents. Seafood irradiation is been presented as an alternative among the different public health intervention measures to control food borne diseases. The objective of this work was to establish, firstly, the radioresistance of Crassostrea brasiliana oysters. The oysters were irradiated with Co-60 radiation with doses of 0, 1.5,3 and 6 kGy. Survival curves a function of time showed that 100% of samples irradiated with 3 kGy survived at least 6 days; among those irradiated with 6 kGy, 100% survived 3 days. These results are encouraging since a dose of 2 kGy is already effective in diminishing oyster bioburden. (author)

  2. Evaluation of γ-radiation-induced DNA damage in two species of bivalves and their relative sensitivity using comet assay

    Energy Technology Data Exchange (ETDEWEB)

    Praveen Kumar, M.K., E-mail: here.praveen@gmail.com [Department of Zoology, Goa University, Goa 403206 (India); Shyama, S.K., E-mail: skshyama@gmail.com [Department of Zoology, Goa University, Goa 403206 (India); Sonaye, B.S. [Department of Radiation Oncology, Goa Medical College, Goa (India); Naik, U Roshini; Kadam, S.B.; Bipin, P.D.; D’costa, A. [Department of Zoology, Goa University, Goa 403206 (India); Chaubey, R.C. [Radiation Biology and Health Science Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-05-01

    Highlights: • Possible genotoxic effect of accidental exposure of aquatic fauna to γ radiation. • Relative sensitivity of bivalves to γ radiation is also analyzed using comet assay. • γ radiation induced significant genetic damage in both the species of bivalves. • P. malabarica and M. casta exhibited a similar level of sensitivity to γ radiation. • Comet assay may be used as a biomarker for the environmental biomonitoring. - Abstract: Ionizing radiation is known to induce genetic damage in diverse groups of organisms. Under accidental situations, large quantities of radioactive elements get released into the environment and radiation emitted from these radionuclides may adversely affect both the man and the non-human biota. The present study is aimed (a) to know the genotoxic effect of gamma radiation on aquatic fauna employing two species of selected bivalves, (b) to evaluate the possible use of ‘Comet assay’ for detecting genetic damage in haemocytes of bivalves as a biomarker for environmental biomonitoring and also (c) to compare the relative sensitivity of two species of bivalves viz. Paphia malabarica and Meretrix casta to gamma radiation. The comet assays was optimized and validated using different concentrations (18, 32 and 56 mg/L) of ethyl methanesulfonate (EMS), a direct-acting reference genotoxic agent, to which the bivalves were exposed for various times (24, 48 and 72 h). Bivalves were irradiated (single acute exposure) with 5 different doses (viz. 2, 4, 6, 8 and 10 Gy) of gamma radiation and their genotoxic effects on the haemocytes were studied using the comet assay. Haemolymph was collected from the adductor muscle at 24, 48 and 72 h of both EMS-exposed and irradiated bivalves and comet assay was carried out using standard protocol. A significant increase in DNA damage was observed as indicated by an increase in % tail DNA damage at different concentrations of EMS and all the doses of gamma radiation as compared to controls in

  3. Evaluation of γ-radiation-induced DNA damage in two species of bivalves and their relative sensitivity using comet assay

    International Nuclear Information System (INIS)

    Highlights: • Possible genotoxic effect of accidental exposure of aquatic fauna to γ radiation. • Relative sensitivity of bivalves to γ radiation is also analyzed using comet assay. • γ radiation induced significant genetic damage in both the species of bivalves. • P. malabarica and M. casta exhibited a similar level of sensitivity to γ radiation. • Comet assay may be used as a biomarker for the environmental biomonitoring. - Abstract: Ionizing radiation is known to induce genetic damage in diverse groups of organisms. Under accidental situations, large quantities of radioactive elements get released into the environment and radiation emitted from these radionuclides may adversely affect both the man and the non-human biota. The present study is aimed (a) to know the genotoxic effect of gamma radiation on aquatic fauna employing two species of selected bivalves, (b) to evaluate the possible use of ‘Comet assay’ for detecting genetic damage in haemocytes of bivalves as a biomarker for environmental biomonitoring and also (c) to compare the relative sensitivity of two species of bivalves viz. Paphia malabarica and Meretrix casta to gamma radiation. The comet assays was optimized and validated using different concentrations (18, 32 and 56 mg/L) of ethyl methanesulfonate (EMS), a direct-acting reference genotoxic agent, to which the bivalves were exposed for various times (24, 48 and 72 h). Bivalves were irradiated (single acute exposure) with 5 different doses (viz. 2, 4, 6, 8 and 10 Gy) of gamma radiation and their genotoxic effects on the haemocytes were studied using the comet assay. Haemolymph was collected from the adductor muscle at 24, 48 and 72 h of both EMS-exposed and irradiated bivalves and comet assay was carried out using standard protocol. A significant increase in DNA damage was observed as indicated by an increase in % tail DNA damage at different concentrations of EMS and all the doses of gamma radiation as compared to controls in

  4. Effects of peroxide and catalase on near ultraviolet radiation sensitivity in Escherichia coli strains

    International Nuclear Information System (INIS)

    The role of peroxide and catalase on NUV radiation sensitivity was examined in two repair competent E. coli strains, AB1157 and B/r. Exponential phase B/r is considerably more sensitive to NUV radiation than exponential phase AB1157. However, resistance to 5 mmol dm-3 H2O2 was induced in both AB1157 and B/r by pretreating growing cells with 30 μmol dm-3 H2O2. Pretreatment also induced resistance to broad-band NUV radiation in these strains. The addition of catalase to the post-irradiation plating medium increased survival to the same extent as that provided by pretreatment with 30 μmol dm-3 H2O2, in both strains. The NUV radiation sensitivity seen in B/r does not appear to be due to a deficiency in enzymes that scavenge H2O2, as a catalase deficient mutant, E. coli UM1, is more resistant to NUV radiation than B/r. Also, assays for H2O2 scavenging ability show little difference between AB1157 and B/r in this respect. Two hypotheses are put forward to account for the sensitivity of exponential phase B/r. Whilst it is apparent that peroxides and catalase do have a role in NUV radiation damage, it is clear that other factors also influence survival under certain conditions. (author)

  5. Radiative measurements at Thule, Greenland: factors affecting the cloud-free shortwave and longwave radiative budget in the Arctic

    OpenAIRE

    Di Biagio, C.; ENEA/UTMEA-TER, S. Maria di Galeria, Italy; Bertagnolio, P. P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; di Sarra, A. G.; ENEA/UTMEA-TER, S. Maria di Galeria, Italy; Eriksen, P.; Danish Meteorological Institute, Copenhagen, Denmark; Ascanius, S. E.; Danish Meteorological Institute, Qanaaq, Greenland; Muscari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia

    2011-01-01

    The Arctic region plays a central role in the global climate system. Modifications in the Arctic radiative budget may strongly influence large scale atmospheric and oceanic circulation. The evaluation of the surface energy balance sensitivity to variations in several parameters, such as surface temperature, water vapour content, surface albedo, and atmospheric aerosols, is one of the main issues in assessing how the Arctic will respond to future climate changes. The NDACC station at Thule...

  6. Development of passive radiation detectors of improved sensitivity

    Science.gov (United States)

    Chakrabarty, M. R.

    1986-01-01

    The future development of a solid track high energy particle detector is discussed. The goal is to improve the sensitivity and lower the threshold of the detector. One most widely used material for such purpose is a plastic commercially known as CR-39. A scheme is presented which involves changing the formula of the monomer, diethylene glycol-bis-allyl carbonate. This is to be accomplished by substituting some heteroatoms for H and substituting sulfur atoms for oxygen in the ether linkages. Use of a new plasticizer to make the etched surface clearer than what has been accomplished as of today is suggested. Possible improvement in acquiring better tracks and increasing the ratio of V sub T/V sub B was planned. This is to be accomplished by changing the composition of the etchants, etching time, and etching temperature.

  7. Influence of pretreatment with selenious yeast on radiation sensitivity

    International Nuclear Information System (INIS)

    The generation of free radical species as a result of radiation exposure is a well-known process. Protection against oxidative damage is possible by endogenous antioxidant defense (enzymatic and nonenzymatic components) but also by drug and dietary treatment. Among the enzymes, glutathione peroxidase (GSH-Px), copper-zinc-containing superoxide dismutase (CuZn SOD), manganese-containing superoxide dismutase (Mn SOD) and catalase (CAT) form the primary intracellular defense system. Nonenzymatic components which regulate autoxidative defense are: glutathione and other sulfhydryl, metals, metalloproteins and antioxidant vitamins. Selenium as a constituent of glutathione peroxidase (GSH-Px) and selenium-containing proteins play an important role in radiosensitivity of the cells. Changes in nutritional Se status would alter the cellular Se concentration, which in turn would result in the loss or restoration of GSH-PX activity. Although it is now evident that a decrease of the selenium and GSH-PX levels can cause radiosensitization, it is less clear whether an increased level can afford radioprotection. Thus, the aim of this work was to study the effect of selenious yeast ingestion on the Se contents in blood, hair, and feces of rats and its effect on radiosensitivity. 3 refs., 1 fig., 3 tabs

  8. Factors affecting mutational specificity induced by ionizing radiation and oxidizing radicals

    International Nuclear Information System (INIS)

    We propose to analyze the factors affecting the specificity of mutational change as induced by ionizing radiation and oxidizing radicals. We want to understand not only the rules that affect base substitution, but also the mechanism(s) by which additions and deletions are produced, since detections are a common consequence of radiation. We wish to carry out this analysis in an in vitro mutation system that permits us to analyze the role of base sequence, of polymerase and of mutagenic agent. Our system is designed to screen out most direct breaks as a cause of mutation and should indicate the changes resulting from base damage to the DNA

  9. Parameters affecting the electron beam sensitivity of poly(methyl methacrylate)

    International Nuclear Information System (INIS)

    Poly(methyl methacrylate), PMMA, is used as a model polymer to determine quantitatively the effect of molecular weight, molecular weight distribution, and tacticity on electron beam sensitivity. The heterotactic, syndiotactic, and isotactic stereoforms of PMMA were synthesized with molecular weights ranging from 104 to 107 and dispersivities from 1.2 to about 10. The G-values as determined by gamma radiation are about 1.3 and are independent of the three parameters. However, the solubility rate of PMMA is very dependent on the tacticity, and the relative solubility rates are in the order syndiotactic < heterotactic much less than isotactic. The weight-average molecular weight ratio was found to give a better correlation with solubility rate ratio than the number-average molecular weight ratio. The molecular size of the developer solvent was shown to have a much greater effect on the solubility rate than the molecular weight of the resist. An optimal developer solvent for PMMA can be systematically selected from a homologous series of n-alkyl acetates which enhance the resist sensitivity

  10. Genetic and molecular characterization of radiation-sensitive mutants of the slime mold, Dictyostelium discoideum

    International Nuclear Information System (INIS)

    Several radiation-sensitive mutants of Dictyostelium discoideum, isolated on the basis of sensitivity to either 60Co gamma rays or 254 nm ultraviolet light (uv), were genetically characterized. The mutations studied can be classified into three types on the basis of their radiation-sensitive phenotype. Type one mutants are very sensitive compared to their parental radiation-resistant strains to both uv and gamma rays with no shoulder on their survival curves. Type two mutants have a sensitivity to both uv and gamma rays intermediate between that of the type one mutants and that of their parental strains; type two mutants have shoulders on both uv and gamma ray survival curves. Type three mutant are sensitive only to uv and are as resistant as their parental strains to gamma rays. The type three mutants have intermediate sensitivities to uv like the type two mutants and have shoulders on their survival curves. Linkage and complementation studies indicate that the ten radiation-sensitive mutations studied identify at least six but probably eight loci involved with DNA repair in D. discoideum. Alkaline sucrose gradient sedimentation profiles of DNA from cells following uv irradiation (15 J/m2) indicate that all type one and type two uv- and gamma-ray-sensitive mutants studied can make and repair single strand breaks. However the type three mutants (radC strains) made few single strand breaks under identical conditions, suggesting that these mutants are defective in excision repair. The evidence obtained indicates that D. discoideum has at least two pathways involved with the repair of uv-induced DNA damage

  11. Development of an efficient process for radiation vulcanization of natural rubber latex using hydroperoxide with sensitizers

    International Nuclear Information System (INIS)

    An attempt was made to reduce radiation dose for radiation vulcanization of natural rubber latex. One of the best methods found was to co-vulcanize the latex using partial radiation vulcanization at 4 kGy with 5 phr n-butyl acrylate as sensitizer and 0.1 phr t-butyl hydroperoxide (BHPO) as co-sensitizer followed by redox vulcanization using either 4 phr fructose at temperature of 60 degree C for 3 hours or 0.2 phr BHPO and 0.4 phr tetra-ethylene pentamine (TEPA) at room temperature for I hour. The rubber film obtained had tensile strength of about 25 MPa, modules 300% of 0. 9 MPa and cross link density of about 1. 5 x 10 sup 19 crosslink/cm sup 3. It was noted that the crosslink density of rubber films from the co-vulcanization was the average value of the values obtained by radiation vulcanization and redox vulcanization

  12. The application of comet- and micronucleus-assay for the determination of individual radiation sensitivity

    International Nuclear Information System (INIS)

    There are various fields in which different radiosensitivities of human beings play a crucial role: occupational exposure, radiation accidents, radiotherapy. Fast methods of analysis are required to determine individual radiation sensitivity. Two such methods are used in our institute since several years: micronuclei and comets. The comet assay, in particular, which does not require cell proliferation, was useful in the identification of radiosensitive individuals (e.g. ataxia telangiectasia patients or people who responded with severe side effects to radiotherapy). (orig.)

  13. Novel computational methods for image analysis and quantification using position sensitive radiation detectors

    OpenAIRE

    Sanchez Crespo, Alejandro

    2005-01-01

    The major advantage of position sensitive radiation detector systems lies in their ability to non invasively map the regional distribution of the emitted radiation in real-time. Three of such detector systems were studied in this thesis, gamma-cameras, positron cameras and CMOS image sensors. A number of physical factors associated to these detectors degrade the qualitative and quantitative properties of the obtained images. These blurring factors could be divided into two groups. The first g...

  14. Rearrangement of RAG-1 recombinase gene in radiation-sensitive ''wasted'' mice

    International Nuclear Information System (INIS)

    Mice recessive for the autosomal gene ''wasted'' (wst) display a disease pattern which includes increased sensitivity to the killing effects of ionizing radiation, immunodeficiency, and neurologic dysfunction. The recent cloning and characterization of recombinase genes (RAG-1/RAG-2) expressed in lymphoid and possibly central nervous system tissues prompted us to examine expression of these genes in DNA repair-deficient/immunodeficient wasted mice. Our results revealed expression of RAG-1 mRNA in spinal cord (but not brain) of control mice; no expression of RAG-1 mRNA was detected in spinal cord or brain from wst/wst mice or their normal littermates (wst/· mice). In thymus tissue, a small RAG-1 transcript (1.0 kb) was detected in wst/wst mice that was not evident in thymus from control mice. In wst/· mice, a two-fold increase in RAG-1 MRNA was evident in thymus tissue. RAG-2 mRNA could only be detected in thymus tissue from wst/· and not from wst/wst or parental control BCF1 mice. Southern blots revealed a rearrangement/deletion within the RAG-1 gene of affected wasted mice, not evident in known strain-specific parental or littermate controls. These results support the idea that the RAG-1 gene may map at or near the locus for the wasted mutation. In addition, they suggest the importance of recombinase function in normal immune and central nervous system development as well as the potential contribution of this gene family to the normal repair of radiation-induced DNA damage

  15. Gadolinium(III) texaphyrin: a tumor selective radiation sensitizer that is detectable by MRI.

    OpenAIRE

    Young, S W; Qing, F; Harriman, A; Sessler, J.L.; Dow, W C; Mody, T D; Hemmi, G W; Hao, Y.; Miller, R. A.

    1996-01-01

    Gadolinium(III) texaphyrin (Gd-tex2+) is representative of a new class of radiation sensitizers detectable by magnetic resonance imaging (MRI). This porphyrin-like complex has a high electron affinity [E1/2 (red.) approximately = -0.08 V versus normal hydrogen electrode] and forms a long-lived pi-radical cation upon exposure to hydrated electrons, reducing ketyl radicals, or superoxide ions. Consistent with these chemical findings, Gd-tex2+ was found to be an efficient radiation sensitizer in...

  16. Increasing sensitivity of quasi-binary media analysis by spectral distribution of gamma-radiation albedo

    International Nuclear Information System (INIS)

    Full text: There has been suggested a method of increasing sensitivity of quasi-binary media analysis based on peculiarities of spectral distribution of gamma-radiation albedo. In quasi-binary media analysis in which there is observed close inter-connection between the effective coefficient of gamma-radiation weakening and heavy component content, it is necessary to obtain the maximum sensitivity of the analytical signal to the parameter being determined. The study showed that in certain geometrical parameters (source-detector distance, air gap between the probe and the medium surface) there is observed the spectrum displacement of the secondary radiation at the medium material composition change. The power distribution displacement of gamma-radiation albedo at the effective coefficient of gamma-radiation weakening change (the medium material composition) is explained by the adequate changing the length of free flight of primary quantum, angle characteristics of scattering and probability of photoelectric absorption of secondary radiation. The essence of the method suggested is in measuring the power corresponding to the maximum in the spectrum of the secondary radiation and the magnitude of gamma-radiation albedo. At the expense of these parameters change at the material composition of the medium analyzed variation there has been obtained the increase of the method contrast range. Depending on the type of the quasi-binary medium (coal, iron ore, carbonate raw materials) there have been determined optimal condition (primary radiation power, probe geometrical parameters) at which there is observed the maximum linear displacement of the power corresponding to the maximum in the secondary radiation spectrum and chosen the power intervals for normal magnitude of gamma-radiation albedo. The method is recommended to analyze raw and industrial materials of quasi-binary composition in which there is observed close correlation dependence between their effective atomic

  17. n-butyl acrylate as a sensitizer for radiation vulcanization of natural rubber latex

    International Nuclear Information System (INIS)

    As a sensitizer for radiation vulcanization of NR latex n-butyl acrylate (n-BA) has several advantages such as high sensitizing efficiency and easiness of removal of residue by drying. However n-BA tends to destabilize NR latex. A study to stabilize NR latex against n-BA has been carried out. The most effective stabilizer is potassium hydroxide. By the addition of 0.2 phr KOH the stability of NR latex is sufficiently improved to withstand the addition of 5 phr n-BA. The sensitizing efficiency of n-BA is so high that the vulcanization dose is 15 kGy with 5 phr n-BA without the addition of carbon tetrachloride as a co-sensitizer. The radiation vulcanized NR latex has enough stability for a 90 days storage. (author)

  18. Effect of ionizing radiation on properties of acrylic pressure sensitive adhesives

    International Nuclear Information System (INIS)

    Pressure-sensitive adhesives for technical application are widely produced. The biological properties of adhesives depend on the type of monomers used. The available literature data as experience of the authors of this study in the area of pressure-sensitive acrylic adhesive, polymers used in medicine, polymerisation in aqueous media, radiation sterilization, permit to make an assumption that it is possible to elaborate the technology of production of pressure-sensitive adhesives in aqueous emulsion for medical applications. Identification of phenomena influencing the adhesive properties, especially its adhesion, cohesion, tack and durability is of great importance. The control of polymer structure is performed by means of adequate selection of conditions of synthesis and parameters of radiation processing. The authors investigate the influence on the final products of such factors as the type and amount of monomers used, their mutual ratio, as well as the ratio monomers and the dose of ionising radiation. There is no available literature information concerning the investigation of resistance of acrylic emulsion adhesive to sterilisation by electron beam. It is known from unpublished research that some adhesives are resistant to radiation, while others undergo destruction. It probably depends on the composition of emulsion, specifically on the additives which modify adhesives. Simultaneous achievement of good cohesion and adhesion in the case of such types of pressure sensitive adhesives is very difficult pressure sensitive adhesives is very difficult

  19. Radioresistant DNA synthesis in cells of patients showing increased chromosomal sensitivity to ionizing radiation

    International Nuclear Information System (INIS)

    The rate of DNA synthesis after γ-irradiation was studied either by analysis of the steady-state distribution of daughter [3H]DNA in alkaline sucrose gradients or by direct assay of the amount of [3H]thymidine incorporated into DNA of fibroblasts derived from a normal donor (LCH882) and from Down's syndrome (LCH944), Werner's syndrome (WS1LE) and xeroderma pigmentosum (XP2LE) patients with chromosomal sensitivity to ionizing radiation. Doses of γ-irradiation that markedly inhibited the rate of DNA synthesis in normal human cells caused almost no inhibition of DNA synthesis in the cells from the affected individuals. The radioresistant DNA synthesis in Down's syndrome cells was mainly due to a much lower inhibition of replicon initiation than that in normal cells; these cells were also more resistant to damage that inhibited replicon elongation. Our data suggest that radioresistant DNA synthesis may be an intrinsic feature of all genetic disorders showing increased radiosensitivity in terms of chromosome aberrations. (orig.)

  20. Comparative study of different surrogate markers for individual radiation sensitivity; Vergleichende Untersuchung verschiedener Surrogatmarker der individuellen zellulaeren Strahlenempfindlichkeit

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, Nele Julia

    2013-12-17

    Radiotherapy is an important part of therapeutic tumor treatment concept. The applied total dose is limited by the unavoidable radiation effect on the surrounding normal tissue and the risk of radiation induced acute or chronic side effects. The clinical radiation sensitivity, i.e. the risk of radiogenic side effects is strongly coupled to the cellular radiation sensitivity. The contribution is focused on the development of a predictive tool for the individual radiation sensitivity for individual radiotherapeutic planning using lymphocytes. Residual foci, i.e. accumulated repair associated proteins at the residual double strand break are supposed to be surrogate markers of the cellular radiation sensitivity. No relation between the foci detection and the G(0)/G(1) was found assay with respect to the individual radiation sensitivity.

  1. Methods and tools for the evaluation of the sensitivity to natural radiations of advanced integrated circuits

    International Nuclear Information System (INIS)

    Atmospheric neutrons, whose fluxes and energies dependent on the altitude, the sun activity and the geographic coordinates, have been identified as being capable to provoke SEE (Single Event Effects), by indirect ionisation, in integrated devices issued from advanced manufacturing processes (nano-metric devices). This concerns not only avionics but also applications operating at ground level. The evaluation of the sensitivity to SEE provoked by natural radiation becomes thus a mandatory step during the selection of devices devoted to be included in applications requiring high reliability. The sensitivity to SEE can be mitigated by different approaches at different levels from manufacturing level (use of particular process technologies such as SOI - Silicon On Isolator -) to the system level (hardware/software redundancy). Independently of the adopted hardening approach, the so-called radiation ground testing are mandatory to evaluate the error rates of a device or a system. During such tests, the DUT (Device Under Test) is exposed to a flux of particles while it performs a given activity. For SEU (Single Event Upsets) radiation ground testing, two main strategies exist: static test: the circuit areas which are supposed to be sensitive to SEUs (registers, memories,...) are initialized with a reference pattern. The content of the sensitive area is periodically compared to the reference pattern to identify potential SEU. Dynamic test: the DUT performs an activity representative of the one it will execute during the final application. Static test: strategies are frequently adopted as they provide the intrinsic sensitivity, in terms of the average number of particles needed to provoke an SEU, of different sensitive areas of the device. From such a strategy can thus be obtained a 'worst case estimation' of the device sensitivity. This thesis aims at giving a description and validating the methodologies required to estimate the sensitivity to radiations of two types of

  2. Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution

    OpenAIRE

    2015-01-01

    A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (all anthropogenic, biomass burning and non-biomass burning) are investigated by performing sensitivity experiments. On the global scale, our results show that land carbon fluxes (GPP and isoprene emission) are not sensitive to pollution aerosols...

  3. Research on relation between professional radiation length of service with radioactive sensitivity parameters of working personnel

    International Nuclear Information System (INIS)

    Objective: To find out infection of professional radiation on radioactive working personnel, and offer pertinence advise and gist for constituting radioactive protection measure. Methods: through epidemiological diagnoses, observe, study and analyse three radiation sensitivity parameters of 912 people. Results: ophthalmological abnormity rate increase along with length of service; outer hemogram and chromosome aberration rate does not increase along with the length of service all the time, but drops from 15a. Conclution: there is a certain infection of professional radiation on the health of working personnel, and we can constitute to take more logical protective measure. (authors)

  4. Radiation dose-rate meter using an energy-sensitive counter

    International Nuclear Information System (INIS)

    A radiation dose-rate meter is described comprising: an energy-sensitive radiation detecting element which generates at an output thereof ionization current pulses having an amplitude proportional to the charge quanta deposited in the radiation detecting element by detected photons of ionizing radiation; a charge-sensitive preamplifier connected to the output of the radiation detecting element; a filter amplifier having a selected filter time constant for generating fixed width pulses at an output thereof in response to each of the step voltage pulses from the preamplifier having an amplitude proportional to the amplitude of each of the step voltage pulses applied to an input thereof; a multi-level discriminator means responsive to the voltage pulses at the output of the filter amplifier for generating a train of count pulses at an output thereof in response to each of the fixed width pulses; and a count rate meter means connected to the output of the multi-level discriminator means of registering the count pulses of each of the train of count pulses as a quantized measure of the radiation dose-rate per unit time of the detected photons of ionizing radiation

  5. Comparison of two different techniques on the human lymphocytes morphology and sensitivity to gamma radiation

    International Nuclear Information System (INIS)

    The lymphocytes in the peripheral blood are divided into two main subclasses: T cells and B cells. These differ from each other in function and in their sensitivity to radiation. The effort to study which group is more sensitive to radiation has resulted in many contradictory results. In the present study we examined whether the methods that are used to separate the lymphocytes from the whole blood, before their separation into subclasses, have an effect on the cells and whether this might contribute to the contradictory results. Blood samples were taken from several normal donors and each sample was devided into two fractions. Lymphocytes in each fraction were separated by one of the two following methods: a) sedimentation of erythrocytes by gravitation; b) separation on Ficoll-Paque density gradient. For cells obtained by these two methods, the ultrastructure was examined by electron microscopy and their ability to incorporate radioactive thymidine was measured. Samples separated on Ficoll-Paque showed a subpopulation with morphological changes similar to those occuring in lymphocytes undergoing stimulation. Unstimulated cells separated on Ficoll-Paque showed greater sensitivity to radiation. The effect of gamma radiation on the capability of lymphocytes to undergo transformation in response to three mitogens; PHA, PWM and Con A was examined. Different mitogens stimulate different lymphocytes subpopulations. There was no difference between the two separation methods regarding the sensitivity to gamma radiation of stimulation by PAH and PWM. The transformation by Con A of lymphocytes separated on Ficoll-Paque was more radiosensitive. This could indicate that the separation by Ficoll-Paque density gradient causes a selective depletion of T lymphocytes that react with Con A and are considered more radioresistant. The use of different methods for separating lymphocytes from whole blood- each has a different influence on the cells- can contribute to contradictory

  6. Effect of protein kinase C inhibitor (PKCI) on radiation sensitivity and c-fos transcription activity

    International Nuclear Information System (INIS)

    The human genetic disorder ataxia-telangiectasia (AT) is a multisystem disease characterized by extreme radiosensitivity. The recent identification of the gene mutated in AT, ATM, and the demonstration that it encodes a homologous domain of phosphatidylinositol 3-kinase (PI3-K), the catalytic subunit of an enzyme involved in transmitting signals from the cell surface to the nucleus, provide support for a role of this gene in signal transduction. Although ionizing radiation was known to induce c-fos transcription, nothing is known about how ATM or PKCI mediated signal transduction pathway modulates the c-fos gene transcription and gene expression. Here we have studied the effect of PKCI on radiation sensitivity and c-fos transcription in normal and AT cells. Normal (LM217) and AT (AT58IVA) cells were transfected with PKCI expression plasmid and the overexpression and integration of PKCI was evaluated by northern blotting and polymerase chain reaction, respectively. 5 Gy of radiation was exposed to LM and AT cells transfected with PKCI expression plasmid and cells were harvested 48 hours after radiation and investigated apoptosis with TUNEL method. The c-fos transcription activity was studied by performing CAT assay of reporter gene after transfection of c-fos CAT plasmid into AT and LM cells. Our results demonstrate for the first time a role of PKCI on. the radiation sensitivity and c-fos expression in LM and AT cells. PKCI increased radiation induced apoptosis in LM cells but reduced apoptosis in AT cells. The basal c-fos transcription activity is 70 times lower in AT cells than that in LM cells. The c-fos transcription activity was repressed by overexpression of PKCI in LM cells but not in AT cells. After induction of c-fos by Ras protein, overexpression of PKCI repressed c-fos transcription in LM cells but not in AT cells. Overexpression of PKCI increased radiation sensitivity and repressed c-fos transcription in LM cells but not in AT cells. The results may be a

  7. The WST survival assay: An easy and reliable method to screen radiation-sensitive individuals

    International Nuclear Information System (INIS)

    An easy, fast and reliable method was developed to screen hundreds of Epstein-Barr virus-transformed cell lines (lymphoblastoid cell lines, LCLs) for radiation sensitivity that were generated from lymphocytes isolated from young lung cancer patients. The WST-1 test explores the metabolic activity of the mitochondria as an indicator for the vital status of cells. Cell proliferation as well as indirect cell death can be quantified by this method on a large scale in microtiter plates. Cell survival was measured at 24- and 48-h post-irradiation with 10 Gy (137Cs source) by the WST-1 assay and Trypan blue staining. To set up the experimental screening conditions and to establish a positive and a negative control, an ATM-mutated cell line from a radiation-sensitive ATM patient and an ATM proficient cell line from a healthy brother were compared. An optimal differentiation between the two cell lines was demonstrated for 10 Gy and 24- and 48-h cell growth after irradiation. Upon screening 120 LCLs of young lung cancer patients under these conditions, 5 of them were found to be radiation sensitive to a high degree of statistical significance. The results have been confirmed by a second laboratory by means of Trypan blue testing. The WST-1 test represents an efficient and reliable method by means of screening for radiation-sensitive cell lines. (authors)

  8. Differential sensitivity to natural ultraviolet radiation among phytoplankton species in Arctic lakes (Spitsbergen, Norway)

    NARCIS (Netherlands)

    Donk, van E.; Faafeng, B.A.; Lange, de H.J.

    2001-01-01

    Incubation experiments demonstrated a differential sensitivity to natural UV-radiation among the dominant phytoplankton species from three Arctic lakes, situated near Ny-Ålesund, Spitsbergen (79° N). The growth of small chlorophytes, diatoms and picocyanobacteria from two oligotrophic lakes was inhi

  9. Differential sensitivity to natural ultraviolet radiation among phytoplankton species in Arctic lakes (Spitsbergen, Norway)

    NARCIS (Netherlands)

    Van Donk, E.; Faafeng, B.A.; De Lange, H.J.; Hessen, D.O.

    2001-01-01

    Incubation experiments demonstrated a differential sensitivity to natural UV-radiation among the dominant phytoplankton species from three Arctic lakes, situated near Ny-Angstrom lesund, Spitsbergen (79 degrees N). The growth of small chlorophytes, diatoms and picocyanobacteria from two oligotrophic

  10. Sensitization to therapy by hyperthermia and radiation. In order to enhance apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, Ichiro; Takahashi, Akihisa; Ohnishi, Ken; Ohnishi, Takeo [Nara Medical Univ., Kashihara (Japan)

    2000-03-01

    Recent findings and authors' investigations are described in this review on sensitization of hyperthermic and radiation therapies for the purpose to enhance apoptosis of cancer cells. Factors concerning the sensitization include cell cycle, repair of radiation-induced DNA damage, recovery of heat-denatured protein and p53 genotype which authors have mainly concerned. Authors found out that apoptosis was inducible by heat and radiation only in cells possessing normal p53 gene. Since cancer cells are generally in the state resistant to apoptosis, elucidation of the mechanism of apoptosis induced by radiation and temperature is important. Factors enhancing the apoptosis in those cells are recombination of normal p53 gene, chemical chaperons, NaCl and heavy particle irradiation. As for a chaperon, treatment of human glioblastoma cells possessing mutated p53 gene with glycerol was found to result in enhancement of apoptosis. Killing effect of carbon beam on cells was higher than that of X-ray regardless to p53 genotype. As above, authors have revealed the importance of p53 in sensitization of cancer cells to heat- and radiation-induced apoptosis. (K.H.)

  11. RecBC enzyme overproduction affects UV and gamma radiation survival of Deinococcus radiodurans.

    Science.gov (United States)

    Khairnar, Nivedita P; Kamble, Vidya A; Misra, Hari S

    2008-01-01

    Deinococcus radiodurans recovering from the effect of acute dose of gamma (gamma) radiation shows a biphasic mechanism of DNA double strands breaks repair that involves an efficient homologous recombination. However, it shows higher sensitivity to near-UV (NUV) than Escherichia coli and lacks RecBC, a DNA strand break (DSB) repair enzyme in some bacteria. Recombinant Deinococcus expressing the recBC genes of E. coli showed nearly three-fold improvements in near-UV tolerance and nearly 2 log cycle reductions in wild type gamma radiation resistance. RecBC over expression effect on radiation response of D. radiodurans was independent of indigenous RecD. Loss of gamma radiation tolerance was attributed to the enhanced rate of in vivo degradation of radiation damaged DNA and delayed kinetics of DSB repair during post-irradiation recovery. RecBC expressing cells of Deinococcus showed wild type response to Far-UV. These results suggest that the overproduction of RecBC competes with the indigenous mechanism of gamma radiation damaged DNA repair while it supports near-UV tolerance in D. radiodurans. PMID:17720630

  12. Sensitivity of mononuclear cells to UV radiation; effect on subsequent stimulation with phytohemagglutinin

    International Nuclear Information System (INIS)

    The ability of peripheral blood mononuclear cells to incorporate 3[H] thymidine into nuclear DNA following stimulation by phytohemagglutinin is reduced by prior exposure to UV radiation in vitro; the reduction is dose and wavelength dependent. The doses required to affect this function of mononuclear cells are higher than the doses required to reduce trypan blue dye exclusion, so that following exposure to radiation populations of cells that are unable to exclude trypan blue dye are still capable of responding to phytohemagglutinin. This finding indicates that trypan blue dye exclusion may not accurately reflect the viability of cells after exposure to UV radiation. (author)

  13. Sensitivity to UV radiation in early life stages of the Mediterranean sea urchin Sphaerechinus granularis (Lamarck)

    Energy Technology Data Exchange (ETDEWEB)

    Nahon, Sarah [UPMC Univ Paris 06, UMR 7621, LOBB, Observatoire Oceanologique, F-66651, Banyuls/mer (France); CNRS, UMR 7621, LOBB, Observatoire Oceanologique, F-66651, Banyuls/mer (France); Castro Porras, Viviana A. [UPMC Univ Paris 06, UMR 7621, LOBB, Observatoire Oceanologique, F-66651, Banyuls/mer (France); Pruski, Audrey M. [UPMC Univ Paris 06, UMR 7621, LOBB, Observatoire Oceanologique, F-66651, Banyuls/mer (France); CNRS, UMR 7621, LOBB, Observatoire Oceanologique, F-66651, Banyuls/mer (France); Charles, Francois [UPMC Univ Paris 06, UMR 7621, LOBB, Observatoire Oceanologique, F-66651, Banyuls/mer (France); CNRS, UMR 7621, LOBB, Observatoire Oceanologique, F-66651, Banyuls/mer (France)], E-mail: charles@obs-banyuls.fr

    2009-03-01

    The sea urchin Sphaerechinus granularis was used to investigate the impact of relevant levels of UV-B radiation on the early life stages of a common Mediterranean free spawning benthic species. Sperm, eggs and embryos were exposed to a range of UV radiation doses. The resulting endpoints were evaluated in terms of fertilisation success, development and survival rates. Above a weighted UV radiation dose of 0.0029 kJ m{sup -2}, fertilisation capability of irradiated sperm decreased rapidly. The exposure of the eggs to 0.0175 kJ m{sup -2} and more led to delayed and inhibited development with ensuing embryonic morphological abnormalities. One-day old larvae remained strongly sensitive to UV radiation as shown by the 50% decrease of the larval survival rate for a dose of 0.025 kJ m{sup -2} UVR. The elevated sensitivity of embryos to experimental UVR went along with a lack of significant amount of sunscreen compounds (e.g., mycosporine-like amino acids) in the eggs. The present results demonstrated that gamete viability and embryonic development may be significantly impaired by solar UV radiation in S. granularis, compromising in this way the reproduction of the species. Unless adaptive behavioural reproductive strategies exist, the influence of ambient UV radiation appears as a selective force for population dynamics of broadcast spawners in the shallow benthic Mediterranean environment.

  14. Radiation-induced increases in sensitivity of cataleptic behavior to haloperidol: possible involvement of prostaglandins

    International Nuclear Information System (INIS)

    The effects of radiation exposure on haloperidol-induced catalepsy were examined in order to determine whether elevated prostaglandins, through an action on dopaminergic autoreceptors, could be involved in the radiation-induced increase in the potency of this neuroleptic. Cataleptic behavior was examined in animals irradiated with various doses of gamma photons (1-150 Gy) and pretreated with a subthreshold dose of haloperidol (0.1 mg/kg). This approach was chosen to maximize any synergistic effects of radiation and haloperidol. After irradiation with doses less than or equal to 30 Gy, the combined treatment of haloperidol and radiation produced catalepsy, whereas neither treatment alone had an effect. This observed catalepsy could be blocked with prior administration of indomethacin, a prostaglandin synthesis inhibitor. Animals exposed to doses of radiation less than or equal to 50 Gy and no haloperidol, however, displayed apparent catalepsy. This effect was also antagonized by indomethacin. Prostaglandins can induce catalepsy and when administered in subthreshold doses along with subthreshold doses of haloperidol, catalepsy was observed. In order to assess a possible action of prostaglandins and radiation on dopaminergic activity, the functioning of striatal dopaminergic autoreceptors was examined by determining the effects of varying concentrations of haloperidol on the K+-evoked release of dopamine from striatal slices obtained from parallel groups of animals treated as above. Results indicated that sensitivity to haloperidol increased (higher K+-evoked dopamine release) in slices from irradiated or prostaglandin-treated animals and that this increase in sensitivity was blocked by indomethacin

  15. Infant Affect and Affect Regulation during the Still-Face Paradigm with Mothers and Fathers: The Role of Infant Characteristics and Parental Sensitivity.

    Science.gov (United States)

    Braungart-Rieker, Julia; Garwood, Molly Murphy; Powers, Bruce P.; Notaro, Paul C.

    1998-01-01

    Examined parents' and 4-month-old infants' behavior during face-to-face interactions. Results indicated that mothers and fathers were equally sensitive to their infants, and that infants' affect and regulatory behaviors were stable across mother-infant and father-infant situations in the still-face model. (BC)

  16. Longitudinal study on work related and individual risk factors affecting radiating neck pain

    OpenAIRE

    Viikari-Juntura, E.; Martikainen, R; Luukkonen, R; Mutanen, P; Takala, E; Riihimaki, H

    2001-01-01

    OBJECTIVES—To study the effects of work related and individual factors affecting radiating neck pain.
METHODS—A longitudinal study was carried out with repeated measurements. A total of 5180 Finnish forest industry workers replied to a questionnaire survey in 1992 (response rate 75%). Response rates to follow up questionnaires in 1993, 1994, and 1995 were 83%, 77%, and 90%, respectively. The outcome variable was the number of days with radiating neck pain during the preceding 12 months with t...

  17. Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sidek, S. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Medical Imaging Unit, Faculty of Medicine, Universiti Teknologi MARA, Selangor (Malaysia); Ramli, N. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Rahmat, K., E-mail: katt_xr2000@yahoo.com [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia); Ramli, N.M.; Abdulrahman, F. [Department of Ophthalmology, Faculty of Medicine, University Malaya, Kuala Lumpur (Malaysia); Tan, L.K. [Department of Biomedical Imaging, University Malaya, Research Imaging Centre, Faculty of Medicine, University Malaya (Malaysia)

    2014-08-15

    Objectives: To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness. Methods: 3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp–Parrish–Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearman's correlation coefficient was carried out. Results: FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r = 0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r = −0.360, p ≤ 0.001). Conclusions: The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity.

  18. Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

    International Nuclear Information System (INIS)

    Objectives: To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness. Methods: 3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp–Parrish–Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearman's correlation coefficient was carried out. Results: FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r = 0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r = −0.360, p ≤ 0.001). Conclusions: The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity

  19. Prematurity does not markedly affect intestinal sensitivity to endotoxins and feeding in pigs.

    Science.gov (United States)

    Bering, Stine B; Bai, Shiping; Zhang, Keying; Sangild, Per T

    2012-08-01

    Preterm neonates show enhanced sensitivity to nutrient maldigestion and bacteria-mediated gut inflammatory disorders, such as necrotising enterocolitis (NEC). We hypothesised that preterm birth increases the sensitivity of intestinal nutrient absorption to endotoxins and that feeding after birth reduces this response. Hence, we investigated the postnatal development of nutrient digestive and absorptive capacity in the preterm and term pig intestine, and its responsiveness to endotoxins. Pigs were delivered by caesarean section at preterm (n 20) or term (n 17) gestation, and the small intestine was collected at birth or after 2 d of colostrum feeding, followed by ex vivo stimulation with lipopolysaccharide endotoxins and mixed gut contents collected from pigs with NEC. Brush border enzyme activities were reduced in newborn preterm v. term pigs (39-45 % reduction, P < 0.05), but normalised after 2 d of feeding. Ex vivo leucine and glucose uptake increased with prenatal age. Bacterial stimulation reduced the nutrient uptake similarly at birth and after 2 d in preterm and term pigs (23-41 % reduction, P < 0.05), whereas IL-6 and TNF-α expression was stimulated only at birth. Toll-like receptor-4 expression increased markedly at day 2 for preterm and term pigs (22-33-fold, P < 0.05) but with much lower expression levels in newborn preterm pigs (approximately 95 %, P < 0.01). In conclusion, digestive and absorptive functions mature in the prenatal period, but are similarly affected by postnatal feeding and bacterial exposure in both preterm and term pigs. Nutrient maldigestion may contribute to NEC development, while a prematurity-related hyper-responsiveness to endotoxins could be less important, at least in pigs. PMID:22136806

  20. Correction method for β-ray sensitivity of two dimensional radiation detector and planar radiation source to be used for the method, and correction device for β-ray sensitivity of two dimensional radiation detector

    International Nuclear Information System (INIS)

    The present invention provides a method of correcting β-ray sensitivity of a two dimensional radiation detector, a planar radiation source to be used for the method and a correction device for β-ray sensitivity of the two dimensional radiation detector. Namely, a planar radiation source on which Pm-147 is coated at a thickness greater than an infinite thickness is brought into intimate contact with or made close to an imaging plate (IP). Then, a phosphorescent intensity (PSL) value at each portion of IP is measured. A ratio of the measured value at each portion relative to the average value is determined as a correction coefficient for β-ray sensitivity. The β-ray sensitivity coefficient is multiplied to the PSL value measured at each of the portions to obtain a true PSL when IP is used subsequently. In this case, Pm-147 is used as the radiation source since it is noted that Pm-147 has an energy distribution approximate to the β-ray energy of C-14 as radioactive isotopes most frequently used, and its half fine is 2.623 years. Namely, the disintegration constant of Pm-147 is 2180 times the disintegration constant of C-14, and it has an extremely high β-ray density. (I.S.)

  1. Multiparametric assessment of radiation effects for the individual radiation sensitivity estimation; Multiparametrische Erfassung von Strahlenwirkungen zur Abschaetzung der individuellen Strahlenempfindlichkeit

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The effects of low dose irradiation are highly relevant for radiation protection in the public. The sensitivity to clastogenic and tumorigenic effects of ionizing radiation (IR) varies considerably amongst individuals. Examples for genetically determined enhanced sensitivity are well known in some hereditary diseases: patients with chromosomal instability syndromes, Ataxia telangiectasia (A-T), Nijmegen Breakage Syndrome (NBS) and Bloom Syndrome (BS) show strongly enhanced sensitivity towards IR, severe immunodeficiencies, and a high incidence for developing leukemias and lymphomas. This obvious coincidence of enhanced radiosensitivity and tumor risk, and the frequently observed enhanced radiosensitivity of genetically non-defined tumor patients indicate that tumor patients may constitute a subpopulation with enriched genetical predisposition for enhanced radiosensitivity. Furthermore, a subpopulation of radiosensitive individuals may be part of the probably inconspicuous total population. For example, individuals heterozygous for the above mentioned genes (and possibly some other genes) show enhanced radiosensitivity if compared with the normal population. In general, heterozygous carriers of those hereditary deficiencies are clinically inconspicuous, but due an haploinsufficiency their tumour risk may be enhanced. This has been shown for mice carrying an heterozygous Nbs1 mutation (J.-Q. Wang, Lyon, pers. Communication). Our findings concerning enhanced radiation-induced chromosomal aberrations in heterozygous Nbs1 cell lines support this notion. The identification of high risk groups with enhanced radiosensitivity is therefore an important task for radioprotection. This project aimed at establishing a procedure which allows to test various cellular parameters as indicators for effects of radiation. A standard protocol for the isolation and cryoconservation of primary blood cells was developed. DNA repair analysis (Comet Assay) and radiation-induced apoptosis

  2. Possible affection of psychic health with regard to exposure to ionizing radiation

    International Nuclear Information System (INIS)

    This report makes part of a series of eight reports which have been drawn up in behalf of the dutch Policy Notition Radiation Standards (BNS). It presents the results of an investigation into the possible affection of psychic health with regard to exposure to ionizing radiation. First the concept 'psychic health' is circumscribed. Subsequently the possible effects of ionizing radiation upon psychic health are entered by outlining two cause-effect chains, in which various variables are distinguished. Thus the framework in which the remainder of the report has been written, is described (ch.2). Ch. 3 deals with the measurability of psychic health and of the various variables in two cause-effect chains. In ch. 4 the found empirical evidence of the effects of ionizing radiation upon psychic health is described. This chapter is especially based upon study of literature. In ch. 5 interviews with users of various radiation sources are reported. In ch. 6 the question of standardization of ionizing radiation with regard to possible (psychic) damage is entered. It is looked if one can speak in terms of 'standards' in case of psychic damage. As far as standardization does not seem to be possible practical alternatives are presented with which eventual psychic damage from ionizing (radiation) sources may be limited. Finally in ch. 7 a comparison is made between the theoretical framework of the (possible) effects of ionizing radiation upon psychic health and the measurability of the therein distinguishable variables on the one hand, and, on the other hand, the empirical materials obtained from the study of the literature and the interviews. (H.W.) 103 refs.; 8 figs

  3. Sensitizers for the Radiation-Induced Vulcanization of Natural Rubber and Other Hydrocarbon Polymers

    International Nuclear Information System (INIS)

    A considerable volume of work has been directed towards the radiation-induced vulcanization of natural and synthetic rubbers, principally with a view to finding a novel application of radiation in the processing and manufacture of rubber products. It is clear that the cost of such processing is high and the mechanical properties of the radiation-vulcanized product are inferior when compared to its sulphur-cured competitor; only in a limited number of properties, e.g. heat aging, is there any improvement. The present work describes a laboratory study of sensitizers which enable the dose for a satisfactory cure to be reduced from 40-50 Mrad to 2-5 Mrad or even lower doses if conditions are carefully controlled. The mechanism of the reaction is described and it is shown that as the radiation-induced cross-linking reaction in the presence of these sensitizers is a chain process, the reaction becomes dose rate dependent and, therefore, it is favoured by the use of isotope sources giving a low dose rate. The physical properties of the cross-linked rubbers are compared with those made by peroxide and sulphur-curing techniques and the differences are explained in terms of the nature of the new type of cross link. Isotope-labelled sensitizers have been used to determine independently the concentration of cross-links produced by irradiation. (author)

  4. A novel high-throughput irradiator for in vitro radiation sensitivity bioassays

    Science.gov (United States)

    Fowler, Tyler L.

    Given the emphasis on more personalized radiation therapy there is an ongoing and compelling need to develop high-throughput screening tools to further examine the biological effects of ionizing radiation on cells, tissues and organ systems in either the research or clinical setting. Conventional x-ray irradiators are designed to provide maximum versatility to radiobiology researchers, typically accommodating small animals, tissue or blood samples, and cellular applications. This added versatility often impedes the overall sensitivity and specificity of an experiment resulting in a trade-off between the number of absorbed doses (or dose rates) and biological endpoints that can be investigated in vitro in a reasonable amount of time. Therefore, modern irradiator designs are incompatible with current high-throughput bioassay technologies. Furthermore, important dosimetry and calibration characteristics (i.e. dose build-up region, beam attenuation, and beam scatter) of these irradiators are typically unknown to the end user, which can lead to significant deviation between delivered dose and intended dose to cells that adversely impact experimental results. Therefore, the overarching goal of this research is to design and develop a robust and fully automated high-throughput irradiator for in vitro radiation sensitivity investigations. Additionally, in vitro biological validation of this system was performed by assessing intracellular reactive oxygen species production, physical DNA double strand breaks, and activation of cellular DNA repair mechanisms. Finally, the high-throughput irradiator was used to investigate autophagic flux, a cellular adaptive response, as a potential biomarker of radiation sensitivity.

  5. Helicity sensitive terahertz radiation detection by dual-grating-gate high electron mobility transistors

    International Nuclear Information System (INIS)

    We report on the observation of a radiation helicity sensitive photocurrent excited by terahertz (THz) radiation in dual-grating-gate (DGG) InAlAs/InGaAs/InAlAs/InP high electron mobility transistors (HEMT). For a circular polarization, the current measured between source and drain contacts changes its sign with the inversion of the radiation helicity. For elliptically polarized radiation, the total current is described by superposition of the Stokes parameters with different weights. Moreover, by variation of gate voltages applied to individual gratings, the photocurrent can be defined either by the Stokes parameter defining the radiation helicity or those for linear polarization. We show that artificial non-centrosymmetric microperiodic structures with a two-dimensional electron system excited by THz radiation exhibit a dc photocurrent caused by the combined action of a spatially periodic in-plane potential and spatially modulated light. The results provide a proof of principle for the application of DGG HEMT for all-electric detection of the radiation's polarization state

  6. Helicity sensitive terahertz radiation detection by dual-grating-gate high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Faltermeier, P.; Olbrich, P.; Probst, W.; Schell, L.; Ganichev, S. D. [Terahertz Center, University of Regensburg, 93040 Regensburg (Germany); Watanabe, T.; Boubanga-Tombet, S. A.; Otsuji, T. [Research Institute of Electrical Communication, Tohoku University, 980-8577 Sendai (Japan)

    2015-08-28

    We report on the observation of a radiation helicity sensitive photocurrent excited by terahertz (THz) radiation in dual-grating-gate (DGG) InAlAs/InGaAs/InAlAs/InP high electron mobility transistors (HEMT). For a circular polarization, the current measured between source and drain contacts changes its sign with the inversion of the radiation helicity. For elliptically polarized radiation, the total current is described by superposition of the Stokes parameters with different weights. Moreover, by variation of gate voltages applied to individual gratings, the photocurrent can be defined either by the Stokes parameter defining the radiation helicity or those for linear polarization. We show that artificial non-centrosymmetric microperiodic structures with a two-dimensional electron system excited by THz radiation exhibit a dc photocurrent caused by the combined action of a spatially periodic in-plane potential and spatially modulated light. The results provide a proof of principle for the application of DGG HEMT for all-electric detection of the radiation's polarization state.

  7. Sucrose Sensitivity of Honey Bees Is Differently Affected by Dietary Protein and a Neonicotinoid Pesticide

    Science.gov (United States)

    Démares, Fabien J.; Crous, Kendall L.; Pirk, Christian W. W.; Nicolson, Susan W.; Human, Hannelie

    2016-01-01

    Over a decade, declines in honey bee colonies have raised worldwide concerns. Several potentially contributing factors have been investigated, e.g. parasites, diseases, and pesticides. Neonicotinoid pesticides have received much attention due to their intensive use in crop protection, and their adverse effects on many levels of honey bee physiology led the European Union to ban these compounds. Due to their neuronal target, a receptor expressed throughout the insect nervous system, studies have focused mainly on neuroscience and behaviour. Through the Geometric Framework of nutrition, we investigated effects of the neonicotinoid thiamethoxam on survival, food consumption and sucrose sensitivity of honey bees (Apis mellifera). Thiamethoxam did not affect protein and carbohydrate intake, but decreased responses to high concentrations of sucrose. Interestingly, when bees ate fixed unbalanced diets, dietary protein facilitated better sucrose detection. Both thiamethoxam and dietary protein influenced survival. These findings suggest that, in the presence of a pesticide and unbalanced food, honey bee health may be severely challenged. Consequences for foraging efficiency and colony activity, cornerstones of honey bee health, are also discussed. PMID:27272274

  8. Sucrose Sensitivity of Honey Bees Is Differently Affected by Dietary Protein and a Neonicotinoid Pesticide.

    Directory of Open Access Journals (Sweden)

    Fabien J Démares

    Full Text Available Over a decade, declines in honey bee colonies have raised worldwide concerns. Several potentially contributing factors have been investigated, e.g. parasites, diseases, and pesticides. Neonicotinoid pesticides have received much attention due to their intensive use in crop protection, and their adverse effects on many levels of honey bee physiology led the European Union to ban these compounds. Due to their neuronal target, a receptor expressed throughout the insect nervous system, studies have focused mainly on neuroscience and behaviour. Through the Geometric Framework of nutrition, we investigated effects of the neonicotinoid thiamethoxam on survival, food consumption and sucrose sensitivity of honey bees (Apis mellifera. Thiamethoxam did not affect protein and carbohydrate intake, but decreased responses to high concentrations of sucrose. Interestingly, when bees ate fixed unbalanced diets, dietary protein facilitated better sucrose detection. Both thiamethoxam and dietary protein influenced survival. These findings suggest that, in the presence of a pesticide and unbalanced food, honey bee health may be severely challenged. Consequences for foraging efficiency and colony activity, cornerstones of honey bee health, are also discussed.

  9. Dysbiosis in Ukrainian Children with Irritable Bowel Syndrome Affected by Natural Radiation

    Directory of Open Access Journals (Sweden)

    Mohammad-Reza Sheikh Sajjadieh

    2012-09-01

    Full Text Available Objective: Microbiota has an important role in human metabolism, nutrition, immunity, and protection against colonization by pathogenic microorganisms. Radiation can harm the beneficial members of the gastrointestinal tract flora.Methods: Our study included 75 rural children aged 4-18 years, who lived in contaminated area exposed to natural environmental radiation with clinical symptoms of irritable bowel syndrome and 20 healthy urban participants aged 5-15 as control group. The intestinal bacterial microbiota was examined from stool samples.Findings: Our results indicated the population levels of microbiota such as Enterobacter, Enterococcus,Lactobacillus and Bifidbacterium in caecal contents in 61 subjects (81.3% was significantly less than in control group.Conclusion: We investigated alternation of the intestinal microbiota affected by ionizing radiation in children with clinical symptoms of irritable bowel syndrome.

  10. Effect of ionizing radiation on voltage-sensitive sodium channels in the brain

    International Nuclear Information System (INIS)

    It has generally been assumed that the mature central nervous system is not sensitive to ionizing radiation because cell division of neurons no longer occurs. In general, rather large doses have been required in order to observe changes in morphological, physiological, biochemical, and behavioral endpoints. In order to focus on one of the most fundamental mechanisms in the generation and propagation of action potentials, experiments were undertaken to determine whether ionizing radiation could alter the ability of the neurotoxins, veratridine and batrachotoxin, to stimulate /sup 22/Na uptake into synaptosomes. Synaptosomal preparations were irradiated with varying doses of high-energy electrons or gamma photons. Both qualities of radiation reduced /sup 22/Na uptake stimulated by either toxin after doses as low as 100 rad in a concentration-dependent manner. When concentration-response curves for the neurotoxins were derived at increasing doses of radiation, the maximum effectiveness of the toxins was progressively diminished. The data suggest that the central nervous system may be more sensitive to the effects of ionizing radiation than previously believed and that the effects observed may reflect a loss of viable sodium channels. Such effects may have biological significance

  11. Radiation sensitivity and gene expression in Enchytraeus japonensis, a species of earth worm

    International Nuclear Information System (INIS)

    The importance of radiological protection of the environment based on scientific principles is gaining international recognition as environment issues garner more attention. Earthworm (annelids) is a ubiquitous soil invertebrate known to play an important role in the maintenance of the soil ecosystem and thus selected as one of 12 kinds of reference animals and plants by the ICRP. In the present study, radiation sensitivity and gene expression in a recently described terrestrial oligochaete, Enchytraeus japonensis (E. japonensis) were studied. E. japonensis worms were acutely irradiated at increasing doses of gamma radiation, and the number of worms after 30 days of radiation was examined. The dose effectively inhibiting 50% of proliferation was approximately 22 Gy, which was comparable to the dose required to elicit growth inhibition in other earthworm species. In order to seek other biological endpoints for more sensitive and/or quicker assessment of radiation effects, gene expression profiling in E. japonensis was also performed, and poly (ADP-ribose) polymerase I (PARP I) was identified as a radiation-responsive gene. PARP I transcript level increased dose-dependently. (author)

  12. Radiation balance of dryland grain sorghum as affected by planting geometry

    International Nuclear Information System (INIS)

    The effects of planting geometry on the radiation balance of dryland grain sorghum (Sorghum bicolor L. cv. DK 46) were studied in a field experiment at the USDA-ARS Conservation and Production Research Laboratory at Bushland, TX, in 1984 on a Pullman clay loam (a fine, mixed, thermic Torrertic Paleustoll). The objective was to reduce the radiation load on a crop through manipulation of planting geometry and to determine whether that would affect crop productivity. Net radiation was 5% higher over wide compared to narrow rows (0.76 and 0.38 m, respectively) when averaged over three population levels from 33 to 110 days after sowing. East-west rows had 14% higher net radiation than north-south rows, averaged over two row spacings. The differences in net radiation were due to daytime responses, presumably shortwave albedo differences. Leaf photosynthesis and transpiration rates and stomatal resistance were measured twice during the grain-filling period. These measurements, taken S days after a period of moderate rains, showed no differences in the plant response due to row spacing or direction treatments. Slightly higher leaf temperatures in the high-population plots may have been related to greater depletion of plant available water than in medium and low population plots (72, 66, and 67% depletion, respectively). After 1 weeks of drying, narrow-row and high-population treatments showed greater stress as evidenced by lower transpiration and photosynthesis rates and higher stomatal resistance and leaf temperature. Soil water depletion was 20% less in narrow than wide rows during a 2-week period spanning the leaf transpiration measurement dates. Leaf photosynthesis, transpiration, temperature, and stomatal resistance were not affected by differences in net radiation due to row spacing or row direction

  13. Sensitivity analysis of numerical weather prediction radiative schemes to forecast direct solar radiation over Australia

    Science.gov (United States)

    Mukkavilli, S. K.; Kay, M. J.; Taylor, R.; Prasad, A. A.; Troccoli, A.

    2014-12-01

    The Australian Solar Energy Forecasting System (ASEFS) project requires forecasting timeframes which range from nowcasting to long-term forecasts (minutes to two years). As concentrating solar power (CSP) plant operators are one of the key stakeholders in the national energy market, research and development enhancements for direct normal irradiance (DNI) forecasts is a major subtask. This project involves comparing different radiative scheme codes to improve day ahead DNI forecasts on the national supercomputing infrastructure running mesoscale simulations on NOAA's Weather Research & Forecast (WRF) model. ASEFS also requires aerosol data fusion for improving accurate representation of spatio-temporally variable atmospheric aerosols to reduce DNI bias error in clear sky conditions over southern Queensland & New South Wales where solar power is vulnerable to uncertainities from frequent aerosol radiative events such as bush fires and desert dust. Initial results from thirteen years of Bureau of Meteorology's (BOM) deseasonalised DNI and MODIS NASA-Terra aerosol optical depth (AOD) anomalies demonstrated strong negative correlations in north and southeast Australia along with strong variability in AOD (~0.03-0.05). Radiative transfer schemes, DNI and AOD anomaly correlations will be discussed for the population and transmission grid centric regions where current and planned CSP plants dispatch electricity to capture peak prices in the market. Aerosol and solar irradiance datasets include satellite and ground based assimilations from the national BOM, regional aerosol researchers and agencies. The presentation will provide an overview of this ASEFS project task on WRF and results to date. The overall goal of this ASEFS subtask is to develop a hybrid numerical weather prediction (NWP) and statistical/machine learning multi-model ensemble strategy that meets future operational requirements of CSP plant operators.

  14. Evaluation of a Fabricated Charge Sensitive Amplifier for a Semiconductor Radiation Detector

    International Nuclear Information System (INIS)

    A CSA(Charge Sensitive Amplifier) was designed and fabricated for application in a radiation detection system based on a semiconductor detector such as Si, SiC, CdZnTe and etc.. A fabricated hybrid.type CSA was evaluated by comparison with a commercially available CSA. A comparison was performed by using calculation of ENC (Equivalent Noise Charge) and by using energy resolutions of fabricated radiation detectors based on Si. In energy resolution comparison, a fabricated CSA showed almost the same performance compared with a commercial one. In this study, feasibility of a fabricated CSA was discussed

  15. Identification of sensitive serum microRNA biomarkers for radiation biodosimetry.

    Directory of Open Access Journals (Sweden)

    Naduparambil Korah Jacob

    Full Text Available Exposure to ionizing radiation through environmental, occupational or a nuclear reactor accident such as the recent Fukushima Daiichi incident often results in major consequences to human health. The injury caused by radiation can manifest as acute radiation syndromes within weeks in organs with proliferating cells such as hematopoietic and gastrointestinal systems. Cancers, fibrosis and degenerative diseases are also reported in organs with differentiated cells, months or years later. Studies conducted on atom bomb survivors, nuclear reactor workers and animal models have shown a direct correlation of these effects with the absorbed dose. Physical dosimeters and the available radio-responsive biologics in body fluids, whose responses are rather indirect, have limitations to accurately evaluate the extent of post exposure damage. We have used an amplification-free, hybridization based quantitative assay utilizing the nCounter multiplex platform developed by nanoString Technologies to compare the levels of over 600 miRNAs in serum from mice irradiated at a range of 1 to 12 Gy at 24 and 48 hr time points. Development of a novel normalization strategy using multiple spike-in oligonucleotides allowed accurate measurement of radiation dose and time dependent changes in serum miRNAs. The response of several evolutionarily conserved miRNAs abundant in serum, were found to be robust and sensitive in the dose range relevant for medical triage and in patients who receive total body radiation as preparative regimen for bone marrow transplantation. Notably, miRNA-150, abundant in lymphocytes, exhibited a dose and time dependent decrease in serum, which we propose as a sensitive marker indicative of lymphocyte depletion and bone marrow damage. Our study has identified several markers useful for evaluation of an individual's response by minimally invasive methods, relevant to triage in case of a radiation accident and evaluation of toxicity and response

  16. The sensitivity of convective aggregation to diabatic processes in idealized radiative-convective equilibrium simulations

    Science.gov (United States)

    Holloway, C. E.; Woolnough, S. J.

    2016-03-01

    Idealized explicit convection simulations of the Met Office Unified Model exhibit spontaneous self-aggregation in radiative-convective equilibrium, as seen in other models in previous studies. This self-aggregation is linked to feedbacks between radiation, surface fluxes, and convection, and the organization is intimately related to the evolution of the column water vapor field. Analysis of the budget of the spatial variance of column-integrated frozen moist static energy (MSE), following Wing and Emanuel (2014), reveals that the direct radiative feedback (including significant cloud longwave effects) is dominant in both the initial development of self-aggregation and the maintenance of an aggregated state. A low-level circulation at intermediate stages of aggregation does appear to transport MSE from drier to moister regions, but this circulation is mostly balanced by other advective effects of opposite sign and is forced by horizontal anomalies of convective heating (not radiation). Sensitivity studies with either fixed prescribed radiative cooling, fixed prescribed surface fluxes, or both do not show full self-aggregation from homogeneous initial conditions, though fixed surface fluxes do not disaggregate an initialized aggregated state. A sensitivity study in which rain evaporation is turned off shows more rapid self-aggregation, while a run with this change plus fixed radiative cooling still shows strong self-aggregation, supporting a "moisture-memory" effect found in Muller and Bony (2015). Interestingly, self-aggregation occurs even in simulations with sea surface temperatures (SSTs) of 295 and 290 K, with direct radiative feedbacks dominating the budget of MSE variance, in contrast to results in some previous studies.

  17. Sensitivity coefficients for the stochastic estimation of the radiation damage to the reactor pressure vessel

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, C.M.; Hernandez Valle, S. [Centro de Investigaciones Tecnologicas, Nucleares y Ambientales, La Habana (Cuba). E-mail: calvarez@ctn.isctn.edu.cu; svalle@ctn.isctn.edu.cu

    2000-07-01

    The construction of the sensitivity matrix in the case of the vessel radiation damage estimation by Monte Carlo techniques poses new problems related to the uncertainties of the obtained responses. In the case of deterministic calculations, the sensitivity coefficient obtention is a straightforward procedure based on the perturbation formalism through the calculation of the adjoint fluxes. In the paper an alternative procedure implementation based on the differential operator method is described with the modifications needed to the used HEXANN-EVALU code for the response estimations in the VVER-440 pressure vessel. (author)

  18. Sensitivity of pathogenic and free-living Leptospira spp. to UV radiation and mitomycin C

    International Nuclear Information System (INIS)

    The habitats for the two major Leptospira spp. differ. The main habitat of L. biflexa is soil and water, whereas L. interrogans primarily resides in the renal tubules of animals. We investigated whether these two species, along with L. illini (species incertae sedis), differ with respect to their sensitivity to UV radiation. The doses of UV resulting in 37, 10 and 1% survival were determined for representive serovars from each species. L. interrogans serovar pomona was 3.0 to 4.8 times more sensitive to UV than the other Leptospira species under the 37, 10, and 1% survival parameters. In comparison to other bacteria, L. interrogans serovar pomona is among the most sensitive to UV. In a qualitative UV sensitivity assay., L. interrogans serovars were found to be in general more sensitive than L. biflexa serovars. All three species were found to have a photoreactivation DNA repair mechanism. Since organisms that are resistant to UV are often resistant to the DNA cross-linking agent mitomycin C, we tested the relative sensitivity of several Leptospira serovars to this compound. With few exceptions, L. biflexa and L. illini serovars were considerably more resistant to mitomycin C than the L. interrogans serovars. The mitomycin C sensitivity assay could be a useful addition to current characterization tests used to differentiate the Leptospira species

  19. Sensitivity of pathogenic and free-living Leptospira spp. to UV radiation and mitomycin C

    Energy Technology Data Exchange (ETDEWEB)

    Stamm, L.V.; Charon, N.W.

    1988-03-01

    The habitats for the two major Leptospira spp. differ. The main habitat of L. biflexa is soil and water, whereas L. interrogans primarily resides in the renal tubules of animals. We investigated whether these two species, along with L. illini (species incertae sedis), differ with respect to their sensitivity to UV radiation. The doses of UV resulting in 37, 10 and 1% survival were determined for representive serovars from each species. L. interrogans serovar pomona was 3.0 to 4.8 times more sensitive to UV than the other Leptospira species under the 37, 10, and 1% survival parameters. In comparison to other bacteria, L. interrogans serovar pomona is among the most sensitive to UV. In a qualitative UV sensitivity assay., L. interrogans serovars were found to be in general more sensitive than L. biflexa serovars. All three species were found to have a photoreactivation DNA repair mechanism. Since organisms that are resistant to UV are often resistant to the DNA cross-linking agent mitomycin C, we tested the relative sensitivity of several Leptospira serovars to this compound. With few exceptions, L. biflexa and L. illini serovars were considerably more resistant to mitomycin C than the L. interrogans serovars. The mitomycin C sensitivity assay could be a useful addition to current characterization tests used to differentiate the Leptospira species.

  20. Crustaceous lichens sensitive monitor of caesium-137 radiation level in terrestrial environment

    Institute of Scientific and Technical Information of China (English)

    Du Chunguang; Zhao Ye; Zhang Jing; Xu Cuihua

    2005-01-01

    The activity of caesium-137 (Bq/kg) in the crustaceous lichens and other samples was determined to prove the feasibility that crustaceous lichens work as a sensitive biology monitor to record the caesium-137 (Bq/kg) radiation levels of terrestrial environment. The measurements were performed with GEM series HPGe (high-purity Germanium) coaxial detector system (ADCAM -100) made by EC & GORTEC Company in USA. It was found that the activity of caesium-137 (Bq/kg) in the crustaceous lichens was one order of magnitude higher than that found in surface soil,and was over three orders of magnitude higher than those found in the familiar biological samples. These results proved that crustaceous lichens may be one of the most sensitive biological monitors about the remote transmission and environmental radiation levels of caesium-137.

  1. Radio sensitivity of rice genotypes to gamma radiations based on seedling traits and physiological indices

    International Nuclear Information System (INIS)

    Three Basmati rice genotypes viz., 00515, 99417 and Super Basmati were examined for varietal differences in radio sensitivity to gamma radiations. Dry healthy seeds were exposed to variable doses of gamma radiations i.e., 150- 400 Gy with 50 Gy intervals. Highly significant differences among the genotypes (p<0.01) for all traits were observed. The differences among radiation treatments were highly significant (p<0.01) for shoot and root length, shoot and root fresh weight, water uptake, chlorophyll contents (a, b), plant height and panicle fertility while non significant differences were observed for germination percentage only. The genotype X dose interactions were non significant for germination percentage, shoot length, root length, shoot fresh weight and plant height indicating stability of performance for characters across different radiation levels. In contrast, chlorophyll (a, b), root fresh weight, water uptake and panicle fertility exhibited significant differences for interactions. Mutagenic treatments shifted mean values towards negative direction for almost all traits but not in a definite pattern. However, water uptake of seeds increased with increasing gamma radiation doses. In general, genotypes displayed variable response towards gamma radiations. (author)

  2. Rapamycin-mediated mTOR inhibition attenuates survivin and sensitizes glioblastoma cells to radiation therapy

    Institute of Scientific and Technical Information of China (English)

    Arunkumar Anandharaj; Senthilkumar Cinghu; Woo-Yoon Park

    2011-01-01

    Survivin, an antiapoptotic protein, is elevated in most malignancies and attributes to radiation resistance in tumors including glioblastoma multiforme. The downregulation of survivin could sensitize glioblastoma ceils to radiation therapy. In this study, we investigated the effect of rapamycin, an inhibitor of mammalian target of rapamycin (mTOR), in attenuating survivin and enhancing the therapeutic efficacy for glioblastoma cells, and elucidated the underlying mechanisms. Here we tested various concentrations of rapamycin (1-8 nM) in combination with radiation dose 4 Gy. Rapamycin effectively modulated the protein kinase B (Akt)/mTOR pathway by inhibiting the phosphorylation of Akt and mTOR proteins, and this inhibition was further enhanced by radiation. The expression level of survivin was decreased in rapamycin pre-treatment glioblastoma ceils followed by radiation; meanwhile, the phosphorylation of H2A histone family member X (H2AX) at serine-139 (γ-H2AX) was increased, p21 protein was also induce on radiation with rapamycin pre-treatment, which enhanced G1 arrest and the accumulation of cells at G0/subG1 phase. Furthermore, the clonogenic cell survival assay revealed a significant dose-dependent decrease in the surviving fraction for all three cell lines pre-treated with rapamycin. Our studies demonstrated that targeting survivin may be an effective approach for radiosensitization of malignant glioblastoma.

  3. Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution

    OpenAIRE

    Strada, Susanna; Unger, Nadine

    2016-01-01

    A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (anthropogenic, biomass burning, and non-biomass burning) are investigated by performing sensitivity experiments. The model framework includes all known light and meteorological responses of photosynthesis, but uses fixed canopy structures and ph...

  4. Co-injection strategies to modify radiation sensitivity and tumor initiation in transgenic Zebrafish

    OpenAIRE

    Langenau, DM; Keefe, MD; Storer, NY; Jette, CA; Smith, ACH; Ceol, CJ; Bourque, C; Look, AT; Zon, LI

    2008-01-01

    The zebrafish has emerged as a powerful genetic model of cancer, but has been limited by the use of stable transgenic approaches to induce disease. Here, a co-injection strategy is described that capitalizes on both the numbers of embryos that can be microinjected and the ability of transgenes to segregate together and exert synergistic effects in forming tumors. Using this mosaic transgenic approach, gene pathways involved in tumor initiation and radiation sensitivity have been identified.

  5. The radiation sensitizing effect of PSK in the treatment for the cervical cancer patients

    International Nuclear Information System (INIS)

    PSK is the protein-bound polysaccharide isolated from Coriolus versicolor (strain CM-101) belonging to Basidiomycetes. It has been widely used as antitumor agent by oral route in Japan for cancer of digestive organs, lung cancer, breast cancer and so on. In this paper, clinical data for the radiation sensitizing effect of PSK in the treatment for the cervical cancer patients is reported. The action mechanism of PSK is still unclear. (Auth.)

  6. The relativity of EGFR and autophagy in the regulating radiation sensitivity of brain glioma cells

    International Nuclear Information System (INIS)

    Radiotherapy is one of the most important methods in the combination therapy against glioma, but resistance of the malignant glioma to radiation limits its clinical contribution. Therefore, it makes great sense to study new mechanisms of radio-resistance. Recent studies show that there is a relationship between EGFR and autophagy in human glioma radiotherapy. More investigations will be needed to select ideal target to enhance the radio-sensitivity of glioma by use of the relationship. (authors)

  7. Growth of untreated and radiation damaged Listeria as affected by environmental factors

    International Nuclear Information System (INIS)

    The growth of untreated Listeria monocytogenes 4 ab No. 10 and that of the surviving fraction of its population treated with 0.8 kGy gamma rays was investigated in a microtitreplate system at incubation temperatures between 3 deg C and 35 deg C in Tryptic Phosphate Broth (TPB) or Brain Heart Infusion Broth (BHIB) media. Time periods to visible growth were recorded. Radiation survivors showed increased salt- and pH-sensitivities and increased minimum temperature for growth in TPB-based media. Adverse effects of sub-optimal environmental factors (reduced water activity, pH and temperature) and radiation injury were much less pronounced in BHIB-based media. The results demonstrate that combining environmental stresses with low-dose irradiation can control growth of L. monocytogenes. (author). 26 refs., 2 figs., 3 tabs

  8. Experimental study of variations in background radiation and the effect on Nuclear Car Wash sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Church, J; Slaughter, D; Norman, E; Asztalos, S; Biltoft, P

    2007-02-07

    Error rates in a cargo screening system such as the Nuclear Car Wash [1-7] depend on the standard deviation of the background radiation count rate. Because the Nuclear Car Wash is an active interrogation technique, the radiation signal for fissile material must be detected above a background count rate consisting of cosmic, ambient, and neutron-activated radiations. It was suggested previously [1,6] that the Corresponding negative repercussions for the sensitivity of the system were shown. Therefore, to assure the most accurate estimation of the variation, experiments have been performed to quantify components of the actual variance in the background count rate, including variations in generator power, irradiation time, and container contents. The background variance is determined by these experiments to be a factor of 2 smaller than values assumed in previous analyses, resulting in substantially improved projections of system performance for the Nuclear Car Wash.

  9. Radiation sensitivity of fibroblast strains from patients with Usher's syndrome, Duchenne muscular dystrophy, and Huntington's disease

    International Nuclear Information System (INIS)

    The colony-forming ability of 10 normal human fibroblast cell strains and of 10 strains representing 3 degenerative diseases of either nerve or muscle cells was determined after exposure of the cells to X-rays or β-particles from tritiated water. Both methods of irradiation yielded similar comparative results. The fibroblast strains from the 5 Usher's syndrome patients and from 1 of the 2 Huntington's disease patients were hypersensitive to radiation, while those from the 3 Duchenne muscular dystrophy patients and the second Huntington's disease patient had normal sensitivity to radiation. These results indicate both disease-specific and strain-specific differences in the survival of fibroblasts after exposure to ionizing radiation. 38 refs.; 2 figs.; 3 tabs

  10. Radiation Sensitivity of some Food Borne Bacterial Pathogens in Animal Foods and Minced Meat

    International Nuclear Information System (INIS)

    Bacteriological examination of 100 samples of animal food stuffs (fish meal and bone and meat meal; as models of dry food materials) and 50 samples of minced meat (as a model of moist food materials) revealed the isolation of different bacterial pathogens; Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Proteus spp., Staph. aureus and Salmonella species, in a decreasing order of occurrence. In the experiment; the dry food stuffs were sterilized in autoclave and the minced meat was sterilized by gamma irradiation at 10 kGy. The efficacy of gamma irradiation against the inoculated bacterial isolates (E coli 0157: H7, Salmonella enteritidis and Staph. aureus) in animal food stuffs and minced meat was investigated. Irradiated samples were stored at room temperature (25 degree C) for 2 weeks. The food borne pathogens used in this study showed a difference in radiation sensitivity. E. coli 0157: H7, Staphylococcus aureus and Salmonella enteritidis were eradicated at 1, 2 and 3 kGy, respectively. Also, inoculated pathogens in minced meat were more sensitive to ionizing radiation than dry animal food stuffs. It could be concluded that low doses of gamma irradiation are effective means of inactivating pathogenic bacteria. This radiation sensitivity is related to the bacterial isolates and the evaluated growth

  11. Nonlinear Quantitative Radiation Sensitivity Prediction Model Based on NCI-60 Cancer Cell Lines

    Directory of Open Access Journals (Sweden)

    Chunying Zhang

    2014-01-01

    Full Text Available We proposed a nonlinear model to perform a novel quantitative radiation sensitivity prediction. We used the NCI-60 panel, which consists of nine different cancer types, as the platform to train our model. Important radiation therapy (RT related genes were selected by significance analysis of microarrays (SAM. Orthogonal latent variables (LVs were then extracted by the partial least squares (PLS method as the new compressive input variables. Finally, support vector machine (SVM regression model was trained with these LVs to predict the SF2 (the surviving fraction of cells after a radiation dose of 2 Gy γ-ray values of the cell lines. Comparison with the published results showed significant improvement of the new method in various ways: (a reducing the root mean square error (RMSE of the radiation sensitivity prediction model from 0.20 to 0.011; and (b improving prediction accuracy from 62% to 91%. To test the predictive performance of the gene signature, three different types of cancer patient datasets were used. Survival analysis across these different types of cancer patients strongly confirmed the clinical potential utility of the signature genes as a general prognosis platform. The gene regulatory network analysis identified six hub genes that are involved in canonical cancer pathways.

  12. Numerical Simulation of Sensitivities of Snow Melting to Spectral Composition of the Incoming Solar Radiation

    Institute of Scientific and Technical Information of China (English)

    LI Weiping; SUN Shufen; WANG Siao; LIU Xin

    2009-01-01

    Snow albedo is an important factor influencing the snow surface energy budget and snow melting,yet uncertainties remain in the calculation of spectrally resolved snow surface albedo because the spectral composition (visible versus near infrared) of the incident solar radiation is seldom available. The influence of the spectral composition of the incoming solar radiation on the snow surface albedo, snow surface energy budget, and final snow ablation is investigated through sensitivity experiments of four snow seasons at two open sites in the Alps by using a multi-layer Snow-Atmosphere-Soil-Transfer scheme (SAST). Since the snow albedo in the near infrared (NIR) spectral band is significantly lower than that in the visible (VIS) band, and almost the entire NIR part of the solar radiation is absorbed in the top layer of the snow pack, given a fixed amount of incoming solar radiation, a lower VIS/NIR ratio implies that more NIR radiation is reaching the ground surface and more is absorbed by the top layer of the snow pack, therefore, speeding up the snow melting and increasing the surface runoff, although a lesser part of the solar radiation in the visible band is transmitted into and trapped by the sub-layer of the snow pack. The above VIS/NIR ratio effect of the incoming solar radiation can result in a couple of days difference in the timing of snow ablation and it becomes more significant in late spring when the total solar radiation is intensified with seasonal evolution. Snow aging also slightly intensifies this VIS/NIR ratio effect.

  13. Tumor progression: analysis of the instability of the metastatic phenotype, sensitivity to radiation and chemotherapy

    International Nuclear Information System (INIS)

    The major complications for tumor therapy are 1) tumor spread (metastasis); 2) the mixed nature of tumors (heterogeneity); and 3) the capacity of tumors to evolve (progress). To study these tumor characteristics, the rat 13762NF mammary adenocarcinoma was cloned and studied for metastatic properties and sensitivities to therapy (chemotherapy, radiation and hyperthermia). The cell clones were heterogeneous and no correlation between metastatic potential and therapeutic sensitivities was observed. Further, these phenotypes were unstable during pasage in vitro; yet, the changes were clone dependent and reproducible using different cryoprotected cell stocks. To understand the phenotypic instability, subclones were isolated from low and high passage cell clones. The results demonstrated that 1) tumor cells are heterogeneous for multiple phenotypes; 2) tumor cells are unstable for multiple phenotypes; 3) the magnitude, direction and time of occurrence of phenotypic drift is clone dependent; 4) the sensitivity of cell clones to ionizing radiation (γ or heat) and chemotherapy agents is independent of their metastatic potential; 5) shifts in metastatic potential and sensitivity to therapy may occur simultaneously but are not linked; and 6) tumor cells independently diverge to form several subpopulations with unique phenotypic profiles

  14. The components in the radiation sensitization of bacterial spores by p-nitroacetophenone

    International Nuclear Information System (INIS)

    p-Nitroacetophenone (PNAP) sensitizes Bacillus megaterium spores under anoxic conditions to the lethal effects of 50 kVp X-rays. Concentrations between approximately 5 x 10-4 M and 3.8 x 10-3 M produce the maximum effect, an increase of about 30 per cent over the anoxic response when the spores are irradiated in water. Compounds that scavenge .OH decrease, but cannot completely eliminate, this maximum amount of sensitization. These results indicate that PNAP acts to increase spores' radiation sensitivity through two seperable types of chemical reactions: one which involves .OH and one which does not. Possible mechanisms responsible for these two components of damage are discussed. In these experiments 1/15 M phosphate buffer acts in several unexpected ways. This concentration itself increased the anoxic spore response by about 9 per cent (relative to the anoxic response in water). In addition, although the maximum amounts of sensitization were the same, the amounts of sensitization from lower PNAP cencentrations differed when the suspending fluid was buffer instead of water. An interaction was also seen during the PNAP-t-butanol experiments; again, the responses at low PNAP concentrations were different in buffer and in water. No mechanisms for these actions of this buffer were suggested, although somewhat similar effects may occur with other organisms. Clearly, such effects must be recognized and evaluated before quantitative analyses of the actions of sensitivity-modifying agents can be completed. (author)

  15. Sensitivity of Escherichia coli acrA mutants to psoralen plus near-ultraviolet radiation

    International Nuclear Information System (INIS)

    The sensitivity to psoralen plus near-ultraviolet radiation (PUVA) was compared in a pair of E. coli strains differing at the acrA locus. Survival was determined for both bacteria and phage lambda. AcrA mutant cells were 40 times more sensitive than wild type to the lethal effect of PUVA. Free lambda phage exposed to PUVA survived as well when plated on acrA mutants as on wild type. In contrast, prophage lambda C1857 ind- carried in lysogenic acrA strains was hypersensitive to PUVA. The enhanced sensitivity of bacterial and lambda DNA, when inside acrA cells, was parallel by an increased photobinding of radiolabelled psoralens in the mutant. Binding was increased specifically to DNA rather than to nucleic acids in general. The difference in psoralen-binding ability determined by the acrA gene persisted after permeabilizing treatment of the cells. (orig./AJ)

  16. A new highly sensitive low-Z LiF-based OSL phosphor for radiation dosimetry

    International Nuclear Information System (INIS)

    A new low-Z lithium fluoride-based optical stimulated luminescent (OSL) phosphor is developed. The phosphor shows good OSL properties, and its sensitivity is comparable with that of the commercial Al2O3:C (Landauer, Inc.) phosphor. For the luminescence averaged over initial 3 s, blue stimulated luminescence (BSL) and green stimulated luminescence (GSL) sensitivities were found to be 0.27 and 4 times, respectively, than that of Al2O3:C (Landauer, Inc.). The BSL decay is fast, and the whole signal decays within 3 s; the GSL decay is relatively slow, and the signal decays in 25 s. The fast decay, good sensitivity, good linearity and its near tissue equivalence (Zeff ∼8.14) will make this phosphor suitable for radiation dosimetry particularly in personnel as well as in medical dosimetry. (authors)

  17. Human cell responses to ionizing radiation are differentially affected by the expressed connexins

    International Nuclear Information System (INIS)

    In multicellular organisms, intercellular communication is essential for homeostatic functions and has a major role in tissue responses to stress. Here, we describe the effects of expression of different connexins, which form gap junction channels with different permeabilities, on the responses of human cells to ionizing radiation. Exposure of confluent HeLa cell cultures to 137Cs γ rays, 3.7 MeV α particles, 1000 MeV protons or 1000 MeV/u iron ions resulted in distinct effects when the cells expressed gap junction channels composed of either connexin26 (Cx26) or connexin32 (Cx32). Irradiated HeLa cells expressing Cx26 generally showed decreased clonogenic survival and reduced metabolic activity relative to parental cells lacking gap junction communication. In contrast, irradiated HeLa cells expressing Cx32 generally showed enhanced survival and greater metabolic activity relative to the control cells. The effects on clonogenic survival correlated more strongly with effects on metabolic activity than with DNA damage as assessed by micronucleus formation. The data also showed that the ability of a connexin to affect clonogenic survival following ionizing radiation can depend on the specific type of radiation. Together, these findings show that specific types of connexin channels are targets that may be exploited to enhance radiotherapeutic efficacy and to formulate countermeasures to the harmful effects of specific types of ionizing radiation. (author)

  18. Subinhibitory concentrations of antibiotics affect stress and virulence gene expression in Listeria monocytogenes and cause enhanced stress sensitivity but do not affect Caco‐2 cell invasion

    DEFF Research Database (Denmark)

    Knudsen, Gitte Maegaard; Holch, Anne; Gram, Lone

    2012-01-01

    Antibiotics can act as signal molecules and affect bacterial gene expression, physiology and virulence. The purpose of this study was to determine whether subinhibitory antibiotic concentrations alter gene expression and physiology of Listeria monocytogenes. Using an agar‐based screening assay with...... promoter fusions, 14 of 16 antibiotics induced or repressed expression of one or more stress and/or virulence genes. Despite ampicillin‐induced up‐regulation of PinlA‐lacZ expression, Caco‐2 cell invasion was not affected. Subinhibitory concentrations of ampicillin and tetracycline caused up‐ and down......‐regulation of stress response genes, respectively, but both antibiotics caused increased sensitivity to acid stress. Six combinations of gene‐antibiotic were quantified in broth cultures and five of the six resulted in the same expression pattern as the agar‐based assay. Antibiotics affect virulence and...

  19. Combined radiation-protective and radiation-sensitizing agents. IV. Measurement of intracellular protector concentrations

    International Nuclear Information System (INIS)

    Radiosensitization of hypoxic V79 Chinese hamster cells by 0.5 mM misonidazole at approximately 0-4 degrees C is substantially enhanced by pretreating the cells overnight with 0.1 mM buthionine sulfoximine, which lowers the cellular glutathione content to 5% of control values (from 4 mM to approximately 0.2 mM). The enhanced sensitization is reversed by concentrations of exogenous cysteine that are much lower (0.02 mM) than the original glutathione content. Reduced Co-enzyme A affords reversal of the enhancing effect at concentrations of about 1 mM. Sodium ascorbate gives no protection at all even at concentrations of 2 mM. The intracellular concentration of the reducing agents was measured using a spin-through oil technique. There was no diffusion of Co-A (MW greater than 750) or ascorbate (excluded by charge) into the cells. In contrast, cysteine was rapidly concentrated by factors of 4-10, even at the low temperatures used. Extracellular ascorbate's inability to radioprotect argues against electron transfer across the cell membrane as a mechanism for radioprotection. This mechanism could have explained the ability of exogenous thiols to radioprotect in former studies using glutathione, and in the present studies using Co-A. The potential of cysteine to be concentrated by cells poses a problem in the interpretation of exogenous protection by non-diffusing thiols, since trace contamination by cysteine could lead to the actual protection observed. Cysteine could also be formed by exchange reactions of exogenous thiols with the disulfide of cysteine, present in all media formulations

  20. Soft x rays as a tool to investigate radiation-sensitive sites in mammalian cells

    International Nuclear Information System (INIS)

    It is now clear that the initial geometrical distribution of primary radiation products in irradiated biological matter is fundamental to the observed end point (cell killing, mutation induction, chromosome aberrations, etc.). In recent years much evidence has accumulated indicating that for all radiations, physical quantities averaged over cellular dimensions (micrometers) are not good predictors of biological effect, and that energy-deposition processes at the nanometer level are critical. Thus irradiation of cells with soft x rays whose secondary electrons have ranges of the order of nanometers is a unique tool for investigating different models for predicting the biological effects of radiation. We demonstrate techniques whereby the biological response of the cell and the physical details of the energy deposition processes may be separated or factorized, so that given the response of a cellular system to, say, soft x rays, the response of the cell to any other radiation may be predicted. The special advantages of soft x rays for eliciting this information and also information concerning the geometry of the radiation sensitive structures within the cell are discussed

  1. Soft x rays as a tool to investigate radiation-sensitive sites in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Brenner, D.J.; Zaider, M.

    1983-01-01

    It is now clear that the initial geometrical distribution of primary radiation products in irradiated biological matter is fundamental to the observed end point (cell killing, mutation induction, chromosome aberrations, etc.). In recent years much evidence has accumulated indicating that for all radiations, physical quantities averaged over cellular dimensions (micrometers) are not good predictors of biological effect, and that energy-deposition processes at the nanometer level are critical. Thus irradiation of cells with soft x rays whose secondary electrons have ranges of the order of nanometers is a unique tool for investigating different models for predicting the biological effects of radiation. We demonstrate techniques whereby the biological response of the cell and the physical details of the energy deposition processes may be separated or factorized, so that given the response of a cellular system to, say, soft x rays, the response of the cell to any other radiation may be predicted. The special advantages of soft x rays for eliciting this information and also information concerning the geometry of the radiation sensitive structures within the cell are discussed.

  2. Sensitivity of Downward Longwave Surface Radiation to Moisture and Cloud Changes in a High-elevation Region

    Science.gov (United States)

    Naud, Catherine M.; Chen, Yonghua; Rangwala, Imtiaz; Miller, James R.

    2013-01-01

    Several studies have suggested enhanced rates of warming in high-elevation regions since the latter half of the twentieth century. One of the potential reasons why enhanced rates of warming might occur at high elevations is the nonlinear relationship between downward longwave radiation (DLR) and specific humidity (q). Using ground-based observations at a high-elevation site in southwestern Colorado and coincident satellite-borne cloud retrievals, the sensitivity of DLR to changes in q and cloud properties is examined and quantified using a neural network method. It is also used to explore how the sensitivity of DLR to q (dDLR/dq) is affected by cloud properties. When binned by season, dDLR/dq is maximum in winter and minimum in summer for both clear and cloudy skies. However, the cloudy-sky sensitivities are smaller, primarily because (1) for both clear and cloudy skies dDLR/dq is proportional to 1/q, for q>0.5 g/kg, and (2) the seasonal values of q are on average larger in the cloudy-sky cases than in clear-sky cases. For a given value of q, dDLR/dq is slightly reduced in the presence of clouds and this reduction increases as q increases. In addition, DLR is found to be more sensitive to changes in cloud fraction when cloud fraction is large. In the limit of overcast skies, DLR sensitivity to optical thickness decreases as clouds become more opaque. These results are based on only one high-elevation site, so the conclusions here need to be tested at other high-elevation locations.

  3. Sensitivity and Acclimation of Three Canopy-Forming Seaweeds to UVB Radiation and Warming

    KAUST Repository

    Xiao, Xi

    2015-12-02

    Canopy-forming seaweeds, as primary producers and foundation species, provide key ecological services. Their responses to multiple stressors associated with climate change could therefore have important knock-on effects on the functioning of coastal ecosystems. We examined interactive effects of UVB radiation and warming on juveniles of three habitat-forming subtidal seaweeds from Western Australia–Ecklonia radiata, Scytothalia dorycarpa and Sargassum sp. Fronds were incubated for 14 days at 16–30°C with or without UVB radiation and growth, health status, photosynthetic performance, and light absorbance measured. Furthermore, we used empirical models from the metabolic theory of ecology to evaluate the sensitivity of these important seaweeds to ocean warming. Results indicated that responses to UVB and warming were species specific, with Sargassum showing highest tolerance to a broad range of temperatures. Scytothalia was most sensitive to elevated temperature based on the reduced maximum quantum yields of PSII; however, Ecklonia was most sensitive, according to the comparison of activation energy calculated from Arrhenius’ model. UVB radiation caused reduction in the growth, physiological responses and thallus health in all three species. Our findings indicate that Scytothalia was capable of acclimating in response to UVB and increasing its light absorption efficiency in the UV bands, probably by up-regulating synthesis of photoprotective compounds. The other two species did not acclimate over the two weeks of exposure to UVB. Overall, UVB and warming would severely inhibit the growth and photosynthesis of these canopy-forming seaweeds and decrease their coverage. Differences in the sensitivity and acclimation of major seaweed species to temperature and UVB may alter the balance between species in future seaweed communities under climate change.

  4. Sensitivity and Acclimation of Three Canopy-Forming Seaweeds to UVB Radiation and Warming.

    Directory of Open Access Journals (Sweden)

    Xi Xiao

    Full Text Available Canopy-forming seaweeds, as primary producers and foundation species, provide key ecological services. Their responses to multiple stressors associated with climate change could therefore have important knock-on effects on the functioning of coastal ecosystems. We examined interactive effects of UVB radiation and warming on juveniles of three habitat-forming subtidal seaweeds from Western Australia-Ecklonia radiata, Scytothalia dorycarpa and Sargassum sp. Fronds were incubated for 14 days at 16-30°C with or without UVB radiation and growth, health status, photosynthetic performance, and light absorbance measured. Furthermore, we used empirical models from the metabolic theory of ecology to evaluate the sensitivity of these important seaweeds to ocean warming. Results indicated that responses to UVB and warming were species specific, with Sargassum showing highest tolerance to a broad range of temperatures. Scytothalia was most sensitive to elevated temperature based on the reduced maximum quantum yields of PSII; however, Ecklonia was most sensitive, according to the comparison of activation energy calculated from Arrhenius' model. UVB radiation caused reduction in the growth, physiological responses and thallus health in all three species. Our findings indicate that Scytothalia was capable of acclimating in response to UVB and increasing its light absorption efficiency in the UV bands, probably by up-regulating synthesis of photoprotective compounds. The other two species did not acclimate over the two weeks of exposure to UVB. Overall, UVB and warming would severely inhibit the growth and photosynthesis of these canopy-forming seaweeds and decrease their coverage. Differences in the sensitivity and acclimation of major seaweed species to temperature and UVB may alter the balance between species in future seaweed communities under climate change.

  5. Folic acid deficiency increases chromosomal instability, chromosome 21 aneuploidy and sensitivity to radiation-induced micronuclei

    International Nuclear Information System (INIS)

    Folic acid deficiency can lead to uracil incorporation into DNA, hypomethylation of DNA, inefficient DNA repair and increase chromosome malsegregation and breakage. Because ionising radiation increases demand for efficient DNA repair and also causes chromosome breaks we hypothesised that folic acid deficiency may increase sensitivity to radiation-induced chromosome breakage. We tested this hypothesis by using the cytokinesis-block micronucleus assay in 10 day WIL2-NS cell cultures at four different folic acid concentrations (0.2, 2, 20, and 200 nM) that span the 'normal' physiological range in humans. The study showed a significant dose-dependent increase in frequency of binucleated cells with micronuclei and/or nucleoplasmic bridges with decreasing folic acid concentration (P < 0.0001, P = 0.028, respectively). These biomarkers of chromosomal instability were also increased in cells irradiated (1.5 Gy γ-rays) on day 9 relative to un-irradiated controls (P < 0.05). Folic acid deficiency and γ-irradiation were shown to have a significant interactive effect on frequency of cells containing micronuclei (two-way ANOVA, interaction P 0.0039) such that the frequency of radiation-induced micronucleated cells (i.e. after subtracting base-line frequency of un-irradiated controls) increased with decreasing folic acid concentration (P-trend < 0.0001). Aneuploidy of chromosome 21, apoptosis and necrosis were increased by folic acid deficiency but not by ionising radiation. The results of this study show that folate status has an important impact on chromosomal stability and is an important modifying factor of cellular sensitivity to radiation-induced genome damage

  6. Does enhanced solar UV-B radiation affect marine primary producers in their natural habitats?

    Science.gov (United States)

    Häder, Donat-P

    2011-01-01

    This article is a highlight of the paper by Li et al. in this issue of Photochemistry and Photobiology as well as a short summary of the research on the effects of solar UV-B radiation on primary production in the oceans. Laboratory experiments under controlled conditions using artificial light sources indicate species-specific damage of many phytoplankton groups. Mesocosm studies in enclosures of limited volume allow analyzing UV effects in multigeneration monitoring of natural assemblages. Field studies to determine the effects of short-wavelength solar radiation require sensitive instrumentation and measurements over extended areas of the open ocean to yield significant results. Results from a cruise described in the paper by Li et al. indicate clear effects of UV-B and UV-A on the photosynthetic carbon fixation of phytoplankton communities with spatial differences between coastal and open-ocean waters. Increasing temperatures and acidification in the ocean due to global climate change may exacerbate the detrimental effects of solar UV-B radiation. PMID:21208211

  7. Influence of individual radiation sensitivity on GPA gene mutation frequency in medical diagnostic X-ray workers

    International Nuclear Information System (INIS)

    Objective: To study the influence of individual radiation sensitivity on GPA gene mutation frequency and the way to adjust it. Methods: Comet assay, cytokinesis-block micronucleus plus 3AB index technique, and multiple linear regression were used to determine the influence of individual radiation sensitivity on GPA gene mutation frequency in medical diagnostic X-ray workers, and then the fitted equation of multiple linear regression was obtained. Results: There was individual difference in radiation sensitivity among medical diagnostic X-ray workers, which is a factor influencing GPA gene mutation frequency. The stronger the individual radiation sensitivity, the higher the GPA gene mutation frequency. The correlation between GPA gene mutation frequency and radiation dose was strengthened after it was adjusted by the individual radiation sensitivity. The equation of multiple linear regression for GPA gene mutation frequency was obtained by the multiple factor analysis: YNφ=24.7 x 10-6 + 0.5 x 10-6X1-99.5 x 10-6X2 + 1.7 x 10-6X3, and the correlation coefficient r=0.673. Conclusions: The relationship between GPA Nφ gene mutation frequency and cumulative dose is improved by adjustment for individual radiation sensitivity. The accumulative dose estimated by using the multiple linear regressions is approximate to the dose estimated by physical method, thus it decreases the uncertainty of estimating cumulative dose and forecasting cancer risk by using GPA gene mutation frequency

  8. Radiation-induced grafting of thermo and pH sensitive polymers

    International Nuclear Information System (INIS)

    Complete text of publication follows. Radiation processing has many advantages over other conventional methods. When using radiation for material processing, no catalysts or additives are needed in order to initiate the reaction. Polymeric films were modified by gamma-radiation grafting of pH and thermo sensitive monomers by one and two step methods, using the preirradiation and the direct methods. The effects of the absorbed dose, monomer concentration and reaction time were investigated. The surface chemistry of grafted samples was analyzed by FTIR-ATR spectroscopy, while their thermal properties were analyzed by TGA and DSC. The stimuli-responsive behavior was studied by swelling and contact angle in water, as well as by DSC. Sensitive films presented a critical pH point and low critical solution temperature. Temperature and pH stimuli-responsive macromolecular materials have attracted great attention because of their obvious applications in biomedicine and biotechnology. This work was supported by DGAPA-UNAM Grant IN200208.

  9. Studies on the Mechanism of Radiation Resistance in Micrococcus Radiodurans and its Sensitization

    International Nuclear Information System (INIS)

    Efficient and accurate repair of radiation-induced lesions in M. radiodurans was investigated as to the cause of its extreme radioresistance. The cells were made permeable to deoxyribonucleoside triphosphate by treatment with non-ionic detergent, Triton X-100. After irradiation with 2 krad gamma rays more than 80% of the single-strand scissions were rejoined in the permeable cells within 10 min at 37°C. This fast repair process requires the presence of deoxyribonucleoside triphosphates and NAD. However, rejoining of DNA strand scission was incomplete after prolonged incubation in the permeable cells. This suggests that alternate repair reaction(s) is necessary for complete recovery. The other type of radiation lesion was found by postirradiation incubation at non-permissive temperature, which markedly sensitizes this bacterium to radiation. Postincubation at this temperature also sensitizes the cells to chemicals that damage DNA. The extreme radioresistance of this bacterium was also lost by mutation and an isolated radiosensitive mutant showed almost the same radiosensitivity as E. coli K12 or B/r. These results are discussed in connection with the extreme radioresistance of M. radiodurans. (author)

  10. Modification of the cellular heat sensitivity of cucumber by growth under supplemental ultraviolet-B radiation

    International Nuclear Information System (INIS)

    The effect of ultraviolet B (UV-B) radiation on the thermal sensitivity of cucumber (Cucumis sativus L.) was studied using UV-B-sensitive cv Poinsett 76 and UV-B-resistant cv Ashley grown under control and elevated (300 mW m-2) UV-B radiation levels. Using both cotyledon and leaf discs, the ability of the tissue to reduce triphenyl tetrazolium chloride (TTC) was determined after treatment at 50 degrees C for various times. Semilogarithmic plots of TTC reduction as a function of time at 50 degrees were curvilinear. They were monophasic for the control cucumber and biphasic for cucumber grown in the presence of elevated UV-B. Treatment of cucumber plants at 37 degrees C for 24 h or of tissue discs at acute UV-B levels for 1 h further modified their response to elevated temperature. These results suggest that growth of cucumber under enhanced UV-B radiation levels increased its ability to withstand elevated temperatures. 19 refs., 2 figs., 2 tabs

  11. Studies on the mechanism of radiation resistance in Micrococcus radiodurans and its sensitization

    International Nuclear Information System (INIS)

    Efficient and accurate repair of radiation-induced lesions in M. radiodurans was investigated as to the cause of its extreme radioresistance. The cells were made permeable to deoxyribonucleoside triphosphate by treatment with non-ionic detergent, Triton X-100. After irradiation with 2 krad gamma rays more than 80% of the single-strand scissions were rejoined in the permeable cells within 10 min at 370C. This fast repair process requires the presence of deoxyribonucleoside triphosphates and NAD. However, rejoining of DNA strand scission was incomplete after prolonged incubation in the permeable cells. This suggests that alternate repair reaction(s) is necessary for complete recovery. The other type of radiation lesion was found by post-irradiation incubation at non-permissive temperature, which markedly sensitizes this bacterium to radiation. Postincubation at this temperature also sensitizes the cells to chemicals that damage DNA. The extreme radioresistance of this bacterium was also lost by mutation and an isolated radiosensitive mutant showed almost the same radiosensitivity as E. coli K12 or B/r. These results are discussed in connection with the extreme radioresistance of M. radiodurans. (author)

  12. NH4+ enrichment and UV radiation interact to affect the photosynthesis and nitrogen uptake of Gracilaria lemaneiformis (Rhodophyta)

    International Nuclear Information System (INIS)

    Highlights: ► Inhibition induced by UVR is alleviated with the enrichment of ammonia. ► Phycoerythrin plays a key protective role against UVR at higher level of ammonia. ► Effect of UVR on the uptakes of nitrate and ammonia is different. - Abstract: Solar ultraviolet radiation (UVR, 280–400 nm) is known to inhibit the photosynthesis of macroalgae, whereas nitrogen availability may alter the sensitivity of the algae to UVR. Here, we show that UV-B (280–315 nm) significantly reduced the net photosynthetic rate of Gracilaria lemaneiformis. This inhibition was alleviated by enrichment with ammonia, which also caused a decrease in dark respiration. The presence of both UV-A (315–400 nm) and UV-B stimulated the accumulation of UV-absorbing compounds. However, this stimulation was not affected by enrichment with ammonia. The content of phycoerythrin (PE) was increased by the enrichment of ammonia only in the absence of UVR. Ammonia uptake and the activity of nitrate reductase were repressed by UVR. However, exposure to UVR had an insignificant effect on the rate of nitrate uptake. In conclusion, increased PE content associated with ammonia enrichment played a protective role against UVR in this alga, and UVR differentially affected the uptake of nitrate and ammonia.

  13. Quantitative assessment of factors affecting the sensitivity of a competitive immunomicroarray for pesticide detection

    DEFF Research Database (Denmark)

    Belleville, Erik; Dufva, Hans Martin; Aamund, J.,; Bruun, L.; Christensen, Claus Bo Vöge

    2003-01-01

    Analytical protein microarrays offering highly parallel analysis can become an invaluable tool for a wide range of immunodiagnostic applications. Here we describe factors that influence the sensitivity of a competitive immunomicroarray that quantifies small molecules; in this case, the pesticides...

  14. Sensitivity analysis of potential events affecting the double-shell tank system and fallback actions

    Energy Technology Data Exchange (ETDEWEB)

    Knutson, B.J.

    1996-09-27

    Sensitivity analyses were performed for fall-back positions (i.e., management actions) to accommodate potential off-normal and programmatic change events overlaid on the waste volume projections and their uncertainties. These sensitivity analyses allowed determining and ranking tank system high-risk parameters and fall- back positions that will accommodate the respective impacts. This quantification of tank system impacts shows periods where tank capacity is sensitive to certain variables that must be carefully managed and/or evaluated. Identifying these sensitive variables and quantifying their impact will allow decision makers to prepare fall-back positions and focus available resources on the highest impact parameters where technical data are needed to reduce waste projection uncertainties. For noncomplexed waste, the period of capacity vulnerability occurs during the years of single-shell tank (SST) retrieval (after approximately 2009) due to the sensitivity to several variables. Ranked by importance these variables include the pretreatment rate and 200-East SST solids transfer volume. For complexed waste, the period of capacity vulnerability occurs during the period after approximately 2005 due to the sensitivity to several variables. Ranked by importance these variables include the pretreatment rate. 200-East SST solids transfer volume. complexed waste reduction factor using evaporation, and 200-west saltwell liquid porosity.

  15. Intervention of oxygen-control ability to radiation sensitivity, cell aging and cell transformation

    International Nuclear Information System (INIS)

    Oxygen is essential for life, and cells have therefore developed numerous adaptive responses to oxygen change. Here, we examined the difference in oxygen-control functions of human (HE), mouse (ME), and Syrian hamster embryo (SHE) cells cultured under different oxygen conditions (0.5%, 2% and 20%), and also examined whether oxygen tensions contributed to cellular lifespan and transformation. HE cells had their replicative lifespan slightly extended under hypoxic (0.5% and 2% oxygen) conditions, but were not immortalized under any of the oxygen concentrations. On the other hand, although ME cells cultured under 20% oxygen tension decreased their proliferation potency temporarily at early stage, all rodent cells were immortalized and acquired anchorage-independency, regardless of oxygen tension. These results suggest that cellular oxygen control function is related to sensitivities cellular immortalization and transformation. To understand intervention of oxygen control ability on cellular immortalization and transformation, we examined the intracellular oxidative level, mitochondria functions and radiation sensitivity. Intracellular oxidative levels of hypoxically cultured rodent cells were significantly enhanced. Mitochondrial membrane potential was altered depend on oxygen tensions, but the change was not parallel to mitochondria number in rodent cells. ME cells were particularly sensitive to oxygen change, and showed a clear oxygen effect on the X-ray survival. However, there was no difference in frequency of radiation-induced micronuclei between HE and ME cells. These results suggest that the response to oxygen change differs markedly in HE and rodent cells. (author)

  16. Phosphoproteomics profiling of human skin fibroblast cells reveals pathways and proteins affected by low doses of ionizing radiation.

    Directory of Open Access Journals (Sweden)

    Feng Yang

    Full Text Available BACKGROUND: High doses of ionizing radiation result in biological damage; however, the precise relationships between long-term health effects, including cancer, and low-dose exposures remain poorly understood and are currently extrapolated using high-dose exposure data. Identifying the signaling pathways and individual proteins affected at the post-translational level by radiation should shed valuable insight into the molecular mechanisms that regulate dose-dependent responses to radiation. PRINCIPAL FINDINGS: We have identified 7117 unique phosphopeptides (2566 phosphoproteins from control and irradiated (2 and 50 cGy primary human skin fibroblasts 1 h post-exposure. Semi-quantitative label-free analyses were performed to identify phosphopeptides that are apparently altered by radiation exposure. This screen identified phosphorylation sites on proteins with known roles in radiation responses including TP53BP1 as well as previously unidentified radiation-responsive proteins such as the candidate tumor suppressor SASH1. Bioinformatic analyses suggest that low and high doses of radiation affect both overlapping and unique biological processes and suggest a role for MAP kinase and protein kinase A (PKA signaling in the radiation response as well as differential regulation of p53 networks at low and high doses of radiation. CONCLUSIONS: Our results represent the most comprehensive analysis of the phosphoproteomes of human primary fibroblasts exposed to multiple doses of ionizing radiation published to date and provide a basis for the systems-level identification of biological processes, molecular pathways and individual proteins regulated in a dose dependent manner by ionizing radiation. Further study of these modified proteins and affected networks should help to define the molecular mechanisms that regulate biological responses to radiation at different radiation doses and elucidate the impact of low-dose radiation exposure on human health.

  17. The Mediterranean summertime ozone maximum: global emission sensitivities and radiative impacts

    Directory of Open Access Journals (Sweden)

    N. A. D. Richards

    2013-03-01

    Full Text Available The Mediterranean troposphere exhibits a marked and localised summertime ozone maximum, which has the potential to strongly impact regional air quality and radiative forcing. The Mediterranean region can be perturbed by long-range pollution import from Northern Europe, North America and Asia, in addition to local emissions, which may all contribute to regional ozone enhancements. We exploit ozone profile observations from the Tropospheric Emission Spectrometer (TES and the Global Ozone Monitoring Experiment-2 (GOME-2 satellite instruments, and an offline 3-D global chemical transport model (TOMCAT to investigate the geographical and vertical structure of the summertime tropospheric ozone maximum over the Mediterranean region. We show that both TES and GOME-2 are able to detect enhanced levels of ozone in the lower troposphere over the region during the summer. These observations, together with surface measurements, are used to evaluate the TOMCAT model's ability to capture the observed ozone enhancement. The model is used to quantify sensitivities of the ozone maximum to anthropogenic and natural volatile organic compound (VOC emissions, anthropogenic NOx emissions, wildfire emissions and long-range import of ozone and precursors. Our results show a dominant sensitivity to natural VOC emissions in the Mediterranean basin over anthropogenic VOC emissions. However, local anthropogenic NOx emissions are result in the overall largest sensitivity in near-surface ozone. We also show that in the lower troposphere, global VOC emissions account for 40% of the ozone sensitivity to VOC emissions in the region, whereas, for NOx the ozone sensitivity to local sources is 9 times greater than that for global emissions at these altitudes. However, in the mid and upper troposphere ozone is most sensitive to non-local emission sources. In terms of radiative effects on regional climate, ozone contributions from non-local emission sources are more important, as

  18. Differential sensitivity of coral larvae to natural levels of ultraviolet radiation during the onset of larval competence.

    KAUST Repository

    Aranda, Manuel

    2011-07-01

    Scleractinian corals are the major builders of the complex structural framework of coral reefs. They live in tropical waters around the globe where they are frequently exposed to potentially harmful ultraviolet radiation (UVR). The eggs and early embryonic stages of some coral species are highly buoyant and remain near the sea surface for prolonged periods of time and may therefore be the most sensitive life stages with respect to UVR. Here, we analysed gene expression changes in five developmental stages of the Caribbean coral Montastraea faveolata to natural levels of UVR using high-density cDNA microarrays (10 930 clones). We found that larvae exhibit low sensitivity to natural levels of UVR during early development as reflected by comparatively few transcriptomic changes in response to UVR. However, we identified a time window of high UVR sensitivity that coincides with the motile planula stage and the onset of larval competence. These processes have been shown to be affected by UVR exposure, and the transcriptional changes we identified explain these observations well. Our analysis of differentially expressed genes indicates that UVR alters the expression of genes associated with stress response, the endoplasmic reticulum, Ca(2+) homoeostasis, development and apoptosis during the motile planula stage and affects the expression of neurogenesis-related genes that are linked to swimming and settlement behaviour at later stages. Taken together, our study provides further data on the impact of natural levels of UVR on coral larvae. Furthermore, our results might allow a better prediction of settlement and recruitment rates after coral spawning events if UVR climate data are taken into account.

  19. Enhancement of radiation sensitivity by erlotinib and celecoxib in A549 human lung cancer cell line

    International Nuclear Information System (INIS)

    Objective: To investigate the role of epidermal growth factor receptor and cyclooxygenase-2 pathways in the erlotinib and celecoxib enhanced radiation sensitivity in A549 human lung cancer cell line. Methods: IC20 of erlotinib and celecoxib on in A549 human lung cancer cells was measured by MTT assay, Clonogenic assays were used to evaluate the antitumor effects of the drugs and X-irradiation. Flow cytometry was used to assess the apoptosis and cell cycle alteration, and Western blot was used for the detection of Akt and phospho-Akt.Results Both erlotinib and celecoxib could inhibit the proliferation of A549 cells in vitro in a dose-dependent manner and their values of IC20 were (5.15 ± 0.14) and (40.32 ± 1.26) μmol/L, respectively. For radiation survival,the values of Dq, D0, SF2 of the combination of two drugs were lower than those of either drug (t=6.62, P<0.05). The SER of celecoxib, erlotinib and their combination were 1.299, 1.503 and 2.217, respectively. Flow cytometry assay showed that both celecoxib and erlotinib could enhance radiation-induced G0/G1 arrest, reduce the cell number in S phase, and enhance radiation-induced apoptosis, especially for the combination of drugs. Western blot assay showed that the expressions of Akt protein were similar in all groups. However, pAkt expression was suppressed by erlotinib and celecoxib, but promoted by radiation. pAkt had the lowest expression in the radiated cells with the treatment of two drugs (t=4.89, P<0.05). Conclusions: The erlotinib and/or celecoxib could enhance radiosensitivity probably by increasing cell apoptosis and reducing the number of S-phase cells with low radiosensitivity. (authors)

  20. Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter

    Energy Technology Data Exchange (ETDEWEB)

    Teperik, Tatiana V., E-mail: tatiana.teperik@u-psud.fr [Univ. Paris-Sud, Institut d’Electronique Fondamentale, UMR 8622, Orsay F-91405 (France); Donostia International Physics Center, Aptdo. 1072, 20080 San Sebastian (Spain); Lustrac, André de [Univ. Paris-Sud, Institut d’Electronique Fondamentale, UMR 8622, Orsay F-91405 (France); Univ. Paris-Ouest, 92410 Ville d’Avray (France)

    2015-12-15

    We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.

  1. Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter

    International Nuclear Information System (INIS)

    We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%

  2. Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter

    Directory of Open Access Journals (Sweden)

    Tatiana V. Teperik

    2015-12-01

    Full Text Available We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.

  3. Electromagnetic cloak to restore the antenna radiation patterns affected by nearby scatter

    Science.gov (United States)

    Teperik, Tatiana V.; de Lustrac, André

    2015-12-01

    We have theoretically verified the feasibility of the concept of mantle cloak for very high frequency (VHF) antenna communications. While the applicability of the concept has been demonstrated for an infinitely long cylindrical obstacle and infinitely long electric source [Y.R. Padooru, A.B. Yakovlev, and P.-Y. Chen and Andrea Alù, J. Appl. Phys., 112, 104902, (2012)], the use of this cloak in realistic conditions is not straightforward. In this paper as an electric source we consider a typical VHF monopole antenna mounted on ground plane together with a metallic cylindrical obstacle. The both ground plane and obstacle affect the antenna radiation scattering. Nevertheless, we could show that the mantle cloak can bee successfully applied to restore the radiation patterns of antenna even when the source, the cylindrical metallic obstacle, and the ground plane have finite length. We have studied the antenna adaptation in the presence of the cloaked obstacle and found that the complete radiation system is still functional in the bandwidth that is reduced only by 11%.

  4. Colchicine sensitizes human hepatocellular carcinoma cells to damages caused by radiation

    Institute of Scientific and Technical Information of China (English)

    Chia-Yuan Liu; Hui-Fen Liao; Shou-Chuan Shih; Shee-Chan Lin; Wen-Hsiung Chang; Cheng-Hsin Chu; Tsang-En Wang; Yu-Jen Chen

    2005-01-01

    AIM: We studied the effect of colchicine combined with radiation on the survival of human hepatocellular carcinoma (HCC) HA22T/VGH cells.METHODS: Twenty-four hours after treatment with 0-8 ng/mL colchicine, HA22T/VGH cells were irradiated at various doses (0, 1, 2, 4, and 8 Gy). Colony assay was performed to assess the surviving cell fraction. Survival curves were fitted by using a linear-quadratic model to estimate the sensitizer enhancement ratio (SER). Flow cytometry was used for cell cycle analysis.RESULTS: Colchicine at lower concentrations (1 and 2 ng/mL) had obvious synergy with radiation to inhibit HCC cell growth, whereas higher concentrations (4 and 8 ng/mL) had only additive effect to radiation. Pretreatment with 1 and 2 ng/mL colchicine for 24-h enhanced cell killing by radiation with SERs of 1.21 and 1.53, respectively.G2/M arrest was only observed with higher colchicine doses (8 and 16 ng/mL) after 24-h treatment; this effect was neither seen with lower doses (1, 2, and 4 ng/mL)nor with any dose after only 1 h of treatment.CONCLUSION: Our results suggest that colchicine has potential as an adjunct to radiotherapy for HCC treatment.Lower doses of colchicine possess radiosensitizing effects via some mechanism other than G2/M arrest. Further study is necessary to elucidate the mechanism.

  5. Increasing oxygenation and radiation sensitivity following photodynamic therapy with verteporfin in the RIF-1 tumor

    Science.gov (United States)

    Pogue, Brian W.; O'Hara, Julia A.; Demidenko, Eugene; Wilmot, Carmen M.; Chen, Bin; Swartz, Harold M.; Hasan, Tayyaba

    2003-06-01

    The combination of verteporfin-based photodynamic therapy (PDT) wiht radiaiton therapy from an orthovoltage device has been examiend in the radiation induced fibrosarcoma tumor model. PDT with verteporfin using a 3 hour delay between injection and the time of optical irradiation has been shown to cause a significant rise in overlal tumor oxygenation. It was huypothesized that this mechanism arises from the reduced oxygen consumption from cells where the PDT has targeted the mitochondria and shut down cellular respiration. Tumor blood flow was measured and found to be still be patent immediately following therapy. This increasing oxygenation was thought to provide an opportunity to increase the radiation sensitivity of the tumor immediately following PDT. When this type of treatment was combined with radiation therapy, a delay in the tumor regrowth time demonstrated that the combined effect was greater than additive. Further study of this phenomenon will provide a more complete mechanistic understanding of the effect and possibly provide a viable pre-treatment for radiation therapy of tumore that increases the therapeutic ratio. This effect could be used to either increase the radiaton dose without increasing the side effects or decrease the dose needed for the same effect on the tumor.

  6. Radiation synthesis of the water-soluble, temperature sensitive polymer, copolymer and study on their properties

    International Nuclear Information System (INIS)

    In order to obtain the water-soluble, temperature sensitive polymer and activated copolymer, the radiation polymerization of N-isopropylacrylamide (NIPAAm), radiation copolymerization of NIPAAm and N-acryloxysuccide (NASI) in aqueous solution or in buffer solution (PBS pH = 7.4) have been carried out by γ-rays from 60Co source at room temperature. The optimum dose range (1-7 kGy), dose rate (>40 Gy/min) and monomer concentration (1%) were chosen through determining the monomer conversion yield and molecular weight (Mw = 6.8 x 105) of product. Synthesis of the reversible linear polymer was performed in tetrahydrofuran (THF) as well. In this way a white powder product could be obtained which possesses of thermally reversible property too, when it was dissolved in water or PBS. The only disadvantages of this method is that the molecular weight of the polymer produced in THF was much lower than that in aqueous solution

  7. High-sensitivity, high-resolution measurements of radiated power on TEXT-U

    International Nuclear Information System (INIS)

    Investigations of a possible radiation drive of edge turbulence in tokamaks require sensitive radiated power measurements having high temporal and spatial resolution. The authors use a commercially available 16-element X-UV-enhanced photodiode array having essentially 100% quantum efficiency from ∼ 25 eV to ≥ 6 keV. The frequency response is presently limited by the amplifiers to ∼ 50 kHz, although the ultimate response is expected to be much higher (>200 kHz). Each element's view is ∼ 0.4 cm wide along the major radius at the plasma midplane while the view of the entire array is ∼ 6.3 cm wide and is scannable over the entire plasma cross section. The details of the system as well as observations of fine spatial structures and fluctuations undetectable by conventional bolometers are presented

  8. Sensitization of prostate cancer to ionizing radiation by targeting poly(ADP-robose) polymerase: preclinical studies

    International Nuclear Information System (INIS)

    Poly(ADP-ribose) polymerase (PARP) is a DNA-binding enzyme which plays important roles in the maintenance of genome stability, immediate cellular responses to DNA damage, and apoptosis. A DNA-binding domain of PARP (PARP-DBD) acts as a dominant-negative mutant by binding to DNA strand breaks irreversibly and sensitizing mammalian cells to DNA-damaging agents (1, 2). To direct the expression of human PARP-DBD to prostate we developed recombinant plasmids expressing the PARP-DBD under the control of the 5'-flanking sequences of the human prostate-specific antigen (PSA) gene. In vitro studies revealed that PSA promoter driven expression of the PARP-DBD showed prostate tissue specificity and androgen responsiveness and sensitized LNCaP cells to DNA-damaging agents, such as ionizing radiation and etoposide (3). To assess the efficiency of this strategy in vivo, we developed a cationic liposome-mediated gene delivery of PARP-DBD plasmid in tumor xenografts of PSA producing and androgen sensitive prostate cancer cells (LNCaP and 22Rv1). Tumor bearing mice were treated with intratumoral liposome-complexed PARP-DBD (LE-PARP-DBD), ionizing radiation (IR) or a combination of LE-PARP-DBD and IR. Control groups received blank liposomes or were left untreated. Administration of LE-PARP-DBD resulted in expression of dominant-negative mutant of PARP in tumor cells and enhanced radiation-induced inhibition of tumor growth. These results provide a proof-of- principle for a novel therapeutic strategy to control prostate cancer. The study was supported in part by grants from the U.S. Army Medical Research and Development Command DAMD 17-00-1-0019 and DAMD 17-00-1-0276 (to V.S.). (1) J.Biol.Chem., 265:18721-18724, 1990; (2) Cancer Research, 58: 3495-3498, 1998; (3) Cancer Research, 62: 6879-6883, 2002

  9. Potential sensitivity of photosynthesis and isoprene emission to direct radiative effects of atmospheric aerosol pollution

    Science.gov (United States)

    Strada, Susanna; Unger, Nadine

    2016-04-01

    A global Earth system model is applied to quantify the impacts of direct anthropogenic aerosol effective radiative forcing on gross primary productivity (GPP) and isoprene emission. The impacts of different pollution aerosol sources (anthropogenic, biomass burning, and non-biomass burning) are investigated by performing sensitivity experiments. The model framework includes all known light and meteorological responses of photosynthesis, but uses fixed canopy structures and phenology. On a global scale, our results show that global land carbon fluxes (GPP and isoprene emission) are not sensitive to pollution aerosols, even under a global decline in surface solar radiation (direct + diffuse) by ˜ 9 %. At a regional scale, GPP and isoprene emission show a robust but opposite sensitivity to pollution aerosols in regions where forested canopies dominate. In eastern North America and Eurasia, anthropogenic pollution aerosols (mainly from non-biomass burning sources) enhance GPP by +5-8 % on an annual average. In the northwestern Amazon Basin and central Africa, biomass burning aerosols increase GPP by +2-5 % on an annual average, with a peak in the northwestern Amazon Basin during the dry-fire season (+5-8 %). The prevailing mechanism varies across regions: light scattering dominates in eastern North America, while a reduction in direct radiation dominates in Europe and China. Aerosol-induced GPP productivity increases in the Amazon and central Africa include an additional positive feedback from reduced canopy temperatures in response to increases in canopy conductance. In Eurasia and northeastern China, anthropogenic pollution aerosols drive a decrease in isoprene emission of -2 to -12 % on an annual average. Future research needs to incorporate the indirect effects of aerosols and possible feedbacks from dynamic carbon allocation and phenology.

  10. Resistant and sensitive single-crystal diamond dosimeters for ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Trucchi, D.M., E-mail: daniele.trucchi@imip.cnr.it [CNR-IMIP, Via Salaria km 29.300, 00016 Monterotondo Scalo, Rome (Italy); Allegrini, P.; Bellucci, A.; Calvani, P. [CNR-IMIP, Via Salaria km 29.300, 00016 Monterotondo Scalo, Rome (Italy); Galbiati, A. [Solaris Photonics Ltd, 23 Almond Avenue, UB7 9 EL, London (United Kingdom); Girolami, M. [CNR-IFN, Via Cineto Romano 42, 00156 Rome (Italy)

    2013-08-01

    Diamond dosimeters for intense ionizing radiation were assembled by developing Ohmic contacts on single-crystal high-purity diamond films. Leakage electrical resistivity of the order of 10{sup 14} Ω cm was measured. Devices were tested with a low-intensity 17.48 keV X-ray beam to probe their maximum sensitivity and the minimum detectable dose-rate. Diamond detectors provided a linearity coefficient to X-ray dose-rate of 1.023±0.07, whose dependence on operative bias voltage is here analyzed.

  11. Sensitive detection of voids in solid materials by refraction-enhanced synchrotron radiation imaging

    International Nuclear Information System (INIS)

    Voids in opaque materials (minute air bubbles) were imaged with synchrotron radiation in a refraction enhancement mode. The voids are imaged by an enhanced x-ray intensity inside the bubble, surrounded by a border region with decreased x-ray intensity, thus allowing sensitive detection of air bubbles in plastic materials. As those 'impurities' could not be depicted with conventional radiography, and optical inspection is not useful if the matrix is opaque, this in-situ imaging technique offers the potential to obtain information of air inclusions, voids, and cracking that appear inadvertently in opaque plastics and possibly in metals as well

  12. Calcineurin inhibitors acutely improve insulin sensitivity without affecting insulin secretion in healthy human volunteers

    DEFF Research Database (Denmark)

    Øzbay, Aygen; Møller, Niels; Juhl, Claus;

    2012-01-01

    tacrolimus has been attributed to both beta cell dysfunction and impaired insulin sensitivity. WHAT THIS STUDY ADDS: This is the first trial to investigate beta cell function and insulin sensitivity using gold standard methodology in healthy human volunteers treated with clinically relevant doses of...... ciclosporin and tacrolimus. We document that both drugs acutely increase insulin sensitivity, while first phase and pulsatile insulin secretion remain unaffected. This study demonstrates that ciclosporin and tacrolimus have similar acute effects on glucose metabolism in healthy humans. AIM The introduction of...... of NODAT remains unclear. We sought to compare the impact of CsA and Tac on glucose metabolism in human subjects. METHODS: Ten healthy men underwent 5 h infusions of CsA, Tac and saline in a randomized, double-blind, crossover study. During infusion glucose metabolism was investigated using following...

  13. MiR-224 expression increases radiation sensitivity of glioblastoma cells

    International Nuclear Information System (INIS)

    Highlights: • MiR-224 expression in established glioblastoma cell lines and sporadic tumor tissues is low. • Exogenous miR-224 expression was found to increase radiation sensitivity of glioblastoma cells. • MiR-224 expression brought about 55–60% reduction in API5 expression levels. • Transfection with API5 siRNA increased radiation sensitivity of glioblastoma cells. • Low miR-224 and high API5 expression correlated with worse survival of GBM patients. - Abstract: Glioblastoma (GBM) is the most common and highly aggressive primary malignant brain tumor. The intrinsic resistance of this brain tumor limits the efficacy of administered treatment like radiation therapy. In the present study, effect of miR-224 expression on growth characteristics of established GBM cell lines was analyzed. MiR-224 expression in the cell lines as well as in primary GBM tumor tissues was found to be low. Exogenous transient expression of miR-224 using either synthetic mimics or stable inducible expression using doxycycline inducible lentiviral vector carrying miR-224 gene, was found to bring about 30–55% reduction in clonogenic potential of U87 MG cells. MiR-224 expression reduced clonogenic potential of U87 MG cells by 85–90% on irradiation at a dose of 6 Gy, a dose that brought about 50% reduction in clonogenic potential in the absence of miR-224 expression. MiR-224 expression in glioblastoma cells resulted in 55–65% reduction in the expression levels of API5 gene, a known target of miR-224. Further, siRNA mediated down-regulation of API5 was also found to have radiation sensitizing effect on glioblastoma cell lines. Analysis of the Cancer Genome Atlas data showed lower miR-224 expression levels in male GBM patients to correlate with poorer survival. Higher expression levels of miR-224 target API5 also showed significant correlation with poorer survival of GBM patients. Up-regulation of miR-224 or down-regulation of its target API5 in combination with radiation therapy

  14. MiR-224 expression increases radiation sensitivity of glioblastoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Upraity, Shailendra; Kazi, Sadaf; Padul, Vijay; Shirsat, Neelam Vishwanath, E-mail: nshirsat@actrec.gov.in

    2014-05-30

    Highlights: • MiR-224 expression in established glioblastoma cell lines and sporadic tumor tissues is low. • Exogenous miR-224 expression was found to increase radiation sensitivity of glioblastoma cells. • MiR-224 expression brought about 55–60% reduction in API5 expression levels. • Transfection with API5 siRNA increased radiation sensitivity of glioblastoma cells. • Low miR-224 and high API5 expression correlated with worse survival of GBM patients. - Abstract: Glioblastoma (GBM) is the most common and highly aggressive primary malignant brain tumor. The intrinsic resistance of this brain tumor limits the efficacy of administered treatment like radiation therapy. In the present study, effect of miR-224 expression on growth characteristics of established GBM cell lines was analyzed. MiR-224 expression in the cell lines as well as in primary GBM tumor tissues was found to be low. Exogenous transient expression of miR-224 using either synthetic mimics or stable inducible expression using doxycycline inducible lentiviral vector carrying miR-224 gene, was found to bring about 30–55% reduction in clonogenic potential of U87 MG cells. MiR-224 expression reduced clonogenic potential of U87 MG cells by 85–90% on irradiation at a dose of 6 Gy, a dose that brought about 50% reduction in clonogenic potential in the absence of miR-224 expression. MiR-224 expression in glioblastoma cells resulted in 55–65% reduction in the expression levels of API5 gene, a known target of miR-224. Further, siRNA mediated down-regulation of API5 was also found to have radiation sensitizing effect on glioblastoma cell lines. Analysis of the Cancer Genome Atlas data showed lower miR-224 expression levels in male GBM patients to correlate with poorer survival. Higher expression levels of miR-224 target API5 also showed significant correlation with poorer survival of GBM patients. Up-regulation of miR-224 or down-regulation of its target API5 in combination with radiation therapy

  15. Phosphoproteomics profiling of human skin fibroblast cells reveals pathways and proteins affected by low doses of ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Feng; Waters, Katrina M.; Miller, John H.; Gritsenko, Marina A.; Zhao, Rui; Du, Xiuxia; Livesay, Eric A.; Purvine, Samuel O.; Monroe, Matthew E.; Wang, Yingchun; Camp, David G.; Smith, Richard D.; Stenoien, David L.

    2010-11-30

    Background: High doses of ionizing radiation result in biological damage, however the precise relationships between long term health effects, including cancer, and low dose exposures remain poorly understood and are currently extrapolated using high dose exposure data. Identifying the signaling pathways and individual proteins affected at the post-translational level by radiation should shed valuable insight into the molecular mechanisms that regulate dose dependent responses to radiation. Principle Findings: We have identified 6845 unique phosphopeptides (2566 phosphoproteins) from control and irradiated (2 and 50 cGy) primary human skin fibroblasts one hour post-exposure. Dual statistical analyses based on spectral counts and peak intensities identified 287 phosphopeptides (from 231 proteins) and 244 phosphopeptides (from 182 proteins) that varied significantly following exposure to 2 and 50 cGy respectively. This screen identified phosphorylation sites on proteins with known roles in radiation responses including TP53BP1 as well as previously unidentified radiation responsive proteins such as the candidate tumor suppressor SASH1. Bioinformatics analyses suggest that low and high doses of radiation affect both overlapping and unique biological processes and suggest a role of MAP kinase and protein kinase A (PKA) signaling in the radiation response as well as differential regulation of p53 networks at low and high doses of radiation. Conlcusions: Our results represent the most comprehensive analysis of the phosphoproteomes of human primary fibroblasts exposed to multiple doses of ionizing radiation published to date and provides a basis for the systems level identification of biological processes, molecular pathways and individual proteins regulated in a dose dependent manner by ionizing radiation. Further study of these modified proteins and affected networks should help to define the molecular mechanisms that regulate biological responses to radiation at

  16. Radiation vulcanization of natural rubber latex using irradiation n-butyl acrylate aqueous emulsion as sensitizer

    International Nuclear Information System (INIS)

    Natural rubber latex was vulcanized by gamma radiation with n-butyl acrylate aqueous emulsion irradiated at dose of 1.5 kGy as sensitizer. The total solid content of latex increases on the irradiation dose. The viscosity of latex on the standing time was investigated and became stable after one month of storage. The gel content of latex films increasing with irradiation dose and attained more than 94% at dose of 10 kGy. Tensile strength of films reached the values of 31MPa; 30 Mpa and 25 Mpa at vulcanization doses of 20 kGy, 15 kGy and 8 kGy for the concentrations of sensitizer 7 phr, 9 phr and 13 phr respectively. Elongation at break decreases as increasing dose. Tear strength of rubber films was from 30-40 N/mm. The tackiness of latex films decreases and smell of vulcanized latex is almost negligible. (author)

  17. The effects of dimethylsulfoxide (DMSO) on the radiation sensitivity of bacterial spores

    International Nuclear Information System (INIS)

    Dimethylsufoxide (DMSO) is a potent sensitizer of irradiated bacterial spores (Bacillus megaterium). It is effective under either anoxic or well-oxygenated conditions; in both cases, DMSO increases the response by a factor of 3 to 4. In water, the oxygen enhancement ratio (OER) with 260-kVp X rays is 1.9, while in pure DMSO, which is not toxic to spores, the OER is reduced to 1.1. Spores exposed to DMSO and then washed and resuspended in water still show most of the DMSO-characteristic sensitization, even when the spores are soaked in water for 24 hr before irradiation. This effect is not attributable to DMSO retention by the spore; instead, we suggest that DMSO causes a long-lasting change in a critical spore component that changes the way the entire cell responds to radiation

  18. Genetics, Synergists, and Age Affect Insecticide Sensitivity of the Honey Bee, Apis mellifera.

    Directory of Open Access Journals (Sweden)

    Frank D Rinkevich

    Full Text Available The number of honey bee colonies in the United States has declined to half of its peak level in the 1940s, and colonies lost over the winter have reached levels that are becoming economically unstable. While the causes of these losses are numerous and the interaction between them is very complex, the role of insecticides has garnered much attention. As a result, there is a need to better understand the risk of insecticides to bees, leading to more studies on both toxicity and exposure. While much research has been conducted on insecticides and bees, there have been very limited studies to elucidate the role that bee genotype and age has on the toxicity of these insecticides. The goal of this study was to determine if there are differences in insecticide sensitivity between honey bees of different genetic backgrounds (Carniolan, Italian, and Russian stocks and assess if insecticide sensitivity varies with age. We found that Italian bees were the most sensitive of these stocks to insecticides, but variation was largely dependent on the class of insecticide tested. There were almost no differences in organophosphate bioassays between honey bee stocks (<1-fold, moderate differences in pyrethroid bioassays (1.5 to 3-fold, and dramatic differences in neonicotinoid bioassays (3.4 to 33.3-fold. Synergism bioassays with piperonyl butoxide, amitraz, and coumaphos showed increased phenothrin sensitivity in all stocks and also demonstrated further physiological differences between stocks. In addition, as bees aged, the sensitivity to phenothrin significantly decreased, but the sensitivity to naled significantly increased. These results demonstrate the variation arising from the genetic background and physiological transitions in honey bees as they age. This information can be used to determine risk assessment, as well as establishing baseline data for future comparisons to explain the variation in toxicity differences for honey bees reported in the

  19. Radiation-induced DNA double-strand break frequencies in human squamous cell carcinoma cell lines of different radiation sensitivities

    International Nuclear Information System (INIS)

    DNA neutral (pH 9-6) filter elution was used to measure radiation-induced DNA double-strand break (dsb) frequencies in eight human squamous cell carcinoma cell lines with radiosensitivities (D0) ranging from 1.07 to 2.66 Gy and D-bar values ranging from 1.46 to 4.08 Gy. Elution profiles of unirradiated samples from more radiosensitive cell lines were all steeper in slope than profiles from resistant cells. The shapes of the dsb induction curves were curvilinear and there was some variability from cell line to cell line in the dose-response for the induction of DNA dsb after exposures to 5-100 Gy 60Co γ-rays. There was no relation between shapes of survival curves and shapes of the dose-responses for the induction of DNA dsb. At low doses (5-25 Gy), three out of four of the more sensitive cell lines (D-bar3.0 Gy). Although the low-dose (5-25 Gy) elution results were variable, they suggest that DNA neutral elution will detect differences between sensitive and resistant tumour cells in initial DNA dsb frequencies. (author)

  20. Pharmacokinetic and Pharmacodynamic Factors That Can Affect Sensitivity to Neurotoxic Sequelae in Elderly Individuals

    OpenAIRE

    Ginsberg, Gary; Hattis, Dale; Russ, Abel; Sonawane, Babasaheb

    2005-01-01

    Early-life exposure to agents that modulate neurologic function can have long-lasting effects well into the geriatric period. Many other factors can affect neurologic function and susceptibility to neurotoxicants in elderly individuals. In this review we highlight pharmacokinetic and pharmacodynamic factors that may increase geriatric susceptibility to these agents. There is a decreasing trend in hepatic metabolizing capacity with advancing years that can affect the ability to clear therapeut...

  1. The distribution of attention in RSVP tasks and its sensitivity to affect, personality traits and estradiol

    OpenAIRE

    Dhinakaran, Janani

    2014-01-01

    In this thesis, the influences of positive and negative affect state, the personality trait neuroticism, and the hormone estradiol on selective attention are explored in three studies. In Study 1 a double-stream RSVP paradigm was used to explore if attention can be spatially diffused and focused by affect. A spatial interpretation of the diffuse mental state was not found. Study 2 studied the distribution of attention as influenced by neuroticism and cognitive control. Results confirmed that ...

  2. Radiation sensitivity of Salmonella isolates relative to resistance to ampicillin, chloramphenicol or gentamicin

    International Nuclear Information System (INIS)

    Antibiotic resistance of inoculated bacteria is a commonly used selective marker. Bacteria resistant to the antibiotic nalidixic acid have been shown to have an increased sensitivity to irradiation. The purpose of this research was to screen a collection of Salmonella isolates for antibiotic resistance and determine the association, if any, of antibiotic resistance with radiation sensitivity. Twenty-four clinical isolates of Salmonella were screened for native resistance to multiple concentrations of ampicillin (Amp), chloramphenicol (Chl), or gentamicin (Gm). Test concentrations were chosen based on established clinical minimum inhibitory concentration (MIC) levels, and isolates were classified as either sensitive or resistant based on their ability to grow at or above the MIC. Salmonella cultures were grown overnight at (37 oC) in antibiotic-amended tryptic soy broth (TSB). Native resistance to Gm was observed with each of the 24 isolates (100%). Eight isolates (33%) were shown to be resistant to Amp, while seven isolates (29%) were shown to be resistant to Chl. In separate experiments, Salmonella cultures were grown overnight (37 oC) in TSB, centrifuged, and the cell pellets were re-suspended in phosphate buffer. The samples were then gamma irradiated at doses up to 1.0 kGy. The D 10 values (the ionizing radiation dose required to reduce the viable number of microorganisms by 90%) were determined for the 24 isolates and they ranged from 0.181 to 0.359 kGy. No correlation was found between the D 10 value of the isolate and its sensitivity or resistance to each of the three antibiotics. Resistance to Amp or Chl is suggested as appropriate resistance marker for Salmonella test strains to be used in studies of irradiation

  3. On high-frequency radiation scattering sensitivity to surface roughness in particulate media

    Science.gov (United States)

    Zohdi, T. I.

    2016-06-01

    This paper analyzes the sensitivity of high-frequency radiation scattering in particulate media, to particle surface roughness. Ray-tracing theory and computation are employed. Since the magnitude of the Poynting vector ray, the irradiance, is the appropriate quantity to be tracked, the behavior of the reflectance, which controls the ratio of the reflected and incident Poynting vector magnitudes, is of primary concern. The reflectance is a highly nonlinear function of the refractive indices and angle of incidence. The present work first addresses the relationship between a single scatterer's sensitivity to its surface roughness and then the response of a large number of scatterers to the surface roughness. The analysis indicates that, for a single scatterer, the sensitivity of the response to roughness decreases, up to a point, and then increases again, i.e., it is nonmonotone. However, for a system of multiple scatterers, this effect vanishes, due to multiple internal reflections which dominate the overall response characteristics. While it was relatively straightforward to compute the overall sensitivity of a single scattering body, for example a sphere, when multiple reflecting bodies are considered, numerical simulations are necessary because the reflected rays from one "rough" body will, in turn, be reflected to another "rough" body, etc. Examples are given for a system of randomly distributed scatterers.

  4. PUFAs acutely affect triacylglycerol-derived skeletal muscle fatty acid uptake and increase postprandial insulin sensitivity

    NARCIS (Netherlands)

    Jans, A.; Konings, E.; Goossens, G.H.; Bouwman, F.G.; Moors, C.C.; Boekschoten, M.V.; Afman, L.A.; Muller, M.R.; Mariman, E.C.; Blaak, E.E.

    2012-01-01

    Background: Dietary fat quality may influence skeletal muscle lipid processing and fat accumulation, thereby modulating insulin sensitivity. Objective: The objective was to examine the acute effects of meals with various fatty acid (FA) compositions on skeletal muscle FA processing and postprandial

  5. Genetics, Synergists, and Age Affect Insecticide Sensitivity of the Honey Bee, Apis mellifera.

    Science.gov (United States)

    Rinkevich, Frank D; Margotta, Joseph W; Pittman, Jean M; Danka, Robert G; Tarver, Matthew R; Ottea, James A; Healy, Kristen B

    2015-01-01

    The number of honey bee colonies in the United States has declined to half of its peak level in the 1940s, and colonies lost over the winter have reached levels that are becoming economically unstable. While the causes of these losses are numerous and the interaction between them is very complex, the role of insecticides has garnered much attention. As a result, there is a need to better understand the risk of insecticides to bees, leading to more studies on both toxicity and exposure. While much research has been conducted on insecticides and bees, there have been very limited studies to elucidate the role that bee genotype and age has on the toxicity of these insecticides. The goal of this study was to determine if there are differences in insecticide sensitivity between honey bees of different genetic backgrounds (Carniolan, Italian, and Russian stocks) and assess if insecticide sensitivity varies with age. We found that Italian bees were the most sensitive of these stocks to insecticides, but variation was largely dependent on the class of insecticide tested. There were almost no differences in organophosphate bioassays between honey bee stocks (bees aged, the sensitivity to phenothrin significantly decreased, but the sensitivity to naled significantly increased. These results demonstrate the variation arising from the genetic background and physiological transitions in honey bees as they age. This information can be used to determine risk assessment, as well as establishing baseline data for future comparisons to explain the variation in toxicity differences for honey bees reported in the literature. PMID:26431171

  6. How iliopelvic lymphoscintigraphy can affect the definition of planning target volume in radiation therapy of pelvic and testicular tumors

    International Nuclear Information System (INIS)

    Purpose: External beam radiation therapy (EBRT) of most intrapelvic and testicular tumors has been generally performed with large fields encompassing both the primary disease and lymphatic drainage. This study was carried out to map the pelvic and periaortic lymphatics by means of iliopelvic lymphoscintigraphy (IPL) in preparation for radiotherapy planning. Methods and Materials: Between January 2000 and October 2001, 70 patients scheduled for EBRT (61 operated on, 52 females, 18 males, mean age 61, range, 24-80), affected with uterine (43), rectal (11), testicular (8), anal (4), penile (2), and vulvar (2) cancers were enrolled in the study. IPL was performed by injection of 99mtechnetium-nanocolloids in the bipedal (70 cases) or bipedal plus perianal (20 cases) sites. The sensitivity of IPL in mapping the lymphatic anatomy was evaluated first. Then three radiation oncologists scored the modifications induced by IPL on the planning target volume (PTV) which had been previously delineated only on the basis of bony landmarks. The original fields were classified 'inadequate' if they failed to match the new PTV by more than 1 cm. Results: IPL sensitivity in showing the inguinal, external iliac, common, and periaortic lymphatics was 100%, 90%, 80%, and 70% in anterior-posterior (A-P) projections, and 100%, 80%, 70%, and 60% in lateral projections respectively. For the presacral and hypogastric ones the sensitivity was 40%. When compared with bony landmarks, IPL changed the delineation of PTV in 24 of 70 A-P P-A fields (34%) and 22 of 58 (38%) lateral fields. Furthermore, 8/12 (67%) lymphadenectomies resulted in being incomplete. No IPL-related toxicity was observed. Conclusion: IPL is a safe, inexpensive (cost: 100 Euros), and effective method to map the lymphatic chains. In the A-P scintigrams these structures were detected in 85% (70-100%) of the patients referred for total pelvis irradiation, and this figure could be higher in subjects not operated on. IPL can also

  7. Position-sensitive radiation monitoring (surface contamination monitor). Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    1999-06-01

    The Shonka Research Associates, Inc. Position-Sensitive Radiation Monitor both detects surface radiation and prepares electronic survey map/survey report of surveyed area automatically. The electronically recorded map can be downloaded to a personal computer for review and a map/report can be generated for inclusion in work packages. Switching from beta-gamma detection to alpha detection is relatively simple and entails moving a switch position to alpha and adjusting the voltage level to an alpha detection level. No field calibration is required when switching from beta-gamma to alpha detection. The system can be used for free-release surveys because it meets the federal detection level sensitivity limits requires for surface survey instrumentation. This technology is superior to traditionally-used floor contamination monitor (FCM) and hand-held survey instrumentation because it can precisely register locations of radioactivity and accurately correlate contamination levels to specific locations. Additionally, it can collect and store continuous radiological data in database format, which can be used to produce real-time imagery as well as automated graphics of survey data. Its flexible design can accommodate a variety of detectors. The cost of the innovative technology is 13% to 57% lower than traditional methods. This technology is suited for radiological surveys of flat surfaces at US Department of Energy (DOE) nuclear facility decontamination and decommissioning (D and D) sites or similar public or commercial sites.

  8. Radiation sensitivity of foodborne pathogens in meat byproducts with different packaging

    International Nuclear Information System (INIS)

    The aim of this study was to determine radiation sensitivity of Escherichia coli O157:H7 and Listeria monocytogenes in edible meat byproducts. Seven beef byproducts (heart, liver, lung, lumen, omasum, large intestine, and small intestine) and four pork byproducts (heart, large intestine, liver, and small intestine) were used. Electron beam irradiation significantly reduced the numbers of pathogenic microorganisms in meat byproducts and no viable cells were detected in both aerobically- and vacuum-packaged samples irradiated at 4 kGy. Meat byproducts packed under vacuum had higher D10 value than the ones packed aerobically. No significant difference was observed between the D10 values of E. coli O157:H7 and L. monocytogenes inoculated in either aerobically or vacuum packaged samples. These results suggest that low-dose electron beam irradiation can significantly decrease microbial numbers and reduce the risk of meat byproduct contamination by the foodborne pathogens. - Highlights: • Radiation sensitivities of pathogens in meat byproduct were tested. • Electron beam irradiation of 3 or 4 kGy reduced pathogens by> 9 log • The D10 values were lower in the aerobic-packaging than under vacuum condition

  9. Sensitivity of radiation monitoring systems in Manila Ports in detecting contamination in foodstuff shipments

    International Nuclear Information System (INIS)

    During the Fukushima Nuclear Power Plant accident in Japan, one of the Philippines' measures to protect the public from radiological hazards of the accident is by monitoring agricultural and food imports for radioactive contamination. In this study, the sensitivity of the mobile Radiation Monitoring System (RM) in Manila Ports in detecting contamination in incoming foodstuff shipments was determined. Large volume synthetic 137Cs reference sources were used to determine the minimum detectable concentration (MDC) of the RMS. The reference sources have radioactivity concentrations that are comparable to the PNRI guidance level of 1000 Bg/kg for 137Cs that is destined for general consumption. Results of the MDC measurements show that the RMS units are sensitive enough to detect radioactivity levels that are within the guidance levels provided that a) the minimum package lot is approximately 200 kg, b) the package is positioned at the detector side, and c) the alarm setting of RMS is as calibrated. It was therefore established that the RMS can be used to initially screen incoming foodstuff shipments of possible contamination and thereby help minimize potential radiation exposures to the public. (author)

  10. Estimations of climate sensitivity based on top-of-atmosphere radiation imbalance

    Directory of Open Access Journals (Sweden)

    B. Lin

    2010-02-01

    Full Text Available Large climate feedback uncertainties limit the accuracy in predicting the response of the Earth's climate to the increase of CO2 concentration within the atmosphere. This study explores a potential to reduce uncertainties in climate sensitivity estimations using energy balance analysis, especially top-of-atmosphere (TOA radiation imbalance. The time-scales studied generally cover from decade to century, that is, middle-range climate sensitivity is considered, which is directly related to the climate issue caused by atmospheric CO2 change. The significant difference between current analysis and previous energy balance models is that the current study targets at the boundary condition problem instead of solving the initial condition problem. Additionally, climate system memory and deep ocean heat transport are considered. The climate feedbacks are obtained based on the constraints of the TOA radiation imbalance and surface temperature measurements of the present climate. In this study, the TOA imbalance value of 0.85 W/m2 is used. Note that this imbalance value has large uncertainties. Based on this value, a positive climate feedback with a feedback coefficient ranging from −1.3 to −1.0 W/m2/K is found. The range of feedback coefficient is determined by climate system memory. The longer the memory, the stronger the positive feedback. The estimated time constant of the climate is large (70~120 years mainly owing to the deep ocean heat transport, implying that the system may be not in an equilibrium state under the external forcing during the industrial era. For the doubled-CO2 climate (or 3.7 W/m2 forcing, the estimated global warming would be 3.1 K if the current estimate of 0.85 W/m2 TOA net radiative heating could be confirmed. With accurate long-term measurements of TOA radiation, the analysis method suggested by this study provides a great potential in the

  11. Genome-wide functional screen identifies a compendium of genes affecting sensitivity to tamoxifen

    OpenAIRE

    Mendes-Pereira, Ana M.; Sims, David; Dexter, Tim; Fenwick, Kerry; Assiotis, Ioannis; Kozarewa, Iwanka; Mitsopoulos, Costas; Hakas, Jarle; Zvelebil, Marketa; Lord, Christopher J; Ashworth, Alan

    2011-01-01

    Therapies that target estrogen signaling have made a very considerable contribution to reducing mortality from breast cancer. However, resistance to tamoxifen remains a major clinical problem. Here we have used a genome-wide functional profiling approach to identify multiple genes that confer resistance or sensitivity to tamoxifen. Combining whole-genome shRNA screening with massively parallel sequencing, we have profiled the impact of more than 56,670 RNA interference reagents targeting 16,4...

  12. Quantitative assessment of factors affecting the sensitivity of a competitive immunomicroarray for pesticide detection

    DEFF Research Database (Denmark)

    Belleville, Erik; Dufva, Hans Martin; Aamund, J.,;

    2003-01-01

    Analytical protein microarrays offering highly parallel analysis can become an invaluable tool for a wide range of immunodiagnostic applications. Here we describe factors that influence the sensitivity of a competitive immunomicroarray that quantifies small molecules; in this case, the pesticides...... dichlobenil metabolite 2,6-dichlorobenzamide (BAM) and atrazine. Free pesticide concentrations in solution are quantified by the competitive binding of fluorescence-conjugated monoclonal antibodies to either surface-immobilized pesticide hapten-protein conjugates or pesticides in solution. We investigated the...

  13. Factors affecting the ozone sensitivity of temperate European grasslands: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Bassin, S. [Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Air Pollution/Climate Group, Reckenholzstrasse 191, CH-8046 Zurich (Switzerland)]. E-mail: seraina.bassin@fal.admin.ch; Volk, M. [Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Air Pollution/Climate Group, Reckenholzstrasse 191, CH-8046 Zurich (Switzerland); Fuhrer, J. [Agroscope FAL Reckenholz, Swiss Federal Research Station for Agroecology and Agriculture, Air Pollution/Climate Group, Reckenholzstrasse 191, CH-8046 Zurich (Switzerland)

    2007-04-15

    This overview of experimentally induced effects of ozone aims to identify physiological and ecological principles, which can be used to classify the sensitivity to ozone of temperate grassland communities in Europe. The analysis of data from experiments with single plants, binary mixtures and multi-species communities illustrates the difficulties to relate individual responses to communities, and thus to identify grassland communities most at risk. Although there is increasing evidence that communities can be separated into broad classes of ozone sensitivity, the database from experiments under realistic conditions with representative systems is too small to draw firm conclusions. But it appears that risk assessments, based on results from individuals or immature mixtures exposed in chambers, are only applicable to intensively managed, productive grasslands, and that the risk of ozone damage for most of perennial grasslands with lower productivity tends to be less than previously expected. - An overview of experimentally induced ozone effects suggests that temperate grasslands could be separated into broad classes of ozone sensitivity based on physiological and ecological principles.

  14. Factors affecting the ozone sensitivity of temperate European grasslands: An overview

    International Nuclear Information System (INIS)

    This overview of experimentally induced effects of ozone aims to identify physiological and ecological principles, which can be used to classify the sensitivity to ozone of temperate grassland communities in Europe. The analysis of data from experiments with single plants, binary mixtures and multi-species communities illustrates the difficulties to relate individual responses to communities, and thus to identify grassland communities most at risk. Although there is increasing evidence that communities can be separated into broad classes of ozone sensitivity, the database from experiments under realistic conditions with representative systems is too small to draw firm conclusions. But it appears that risk assessments, based on results from individuals or immature mixtures exposed in chambers, are only applicable to intensively managed, productive grasslands, and that the risk of ozone damage for most of perennial grasslands with lower productivity tends to be less than previously expected. - An overview of experimentally induced ozone effects suggests that temperate grasslands could be separated into broad classes of ozone sensitivity based on physiological and ecological principles

  15. Fecal calprotectin is equally sensitive in Crohn's disease affecting the small bowel and colon

    DEFF Research Database (Denmark)

    Jensen, Michael Dam; Kjeldsen, Jens; Nathan, Torben

    2011-01-01

    The utility of fecal calprotectin (fCal) in small bowel Crohn's disease (CD) remains to be clarified. The primary aim of this study was to determine levels of fCal in CD restricted to the small bowel compared with CD affecting the colon, in patients undergoing their first diagnostic work-up. In...

  16. Factors Affecting Sensitivity to Frequency Change in School-Age Children and Adults

    Science.gov (United States)

    Buss, Emily; Taylor, Crystal N.; Leibold, Lori J.

    2014-01-01

    Purpose: The factors affecting frequency discrimination in school-age children are poorly understood. The goal of the present study was to evaluate developmental effects related to memory for pitch and the utilization of temporal fine structure. Method: Listeners were 5.1- to 13.6-year-olds and adults, all with normal hearing. A subgroup of…

  17. Estimating option values of solar radiation management assuming that climate sensitivity is uncertain.

    Science.gov (United States)

    Arino, Yosuke; Akimoto, Keigo; Sano, Fuminori; Homma, Takashi; Oda, Junichiro; Tomoda, Toshimasa

    2016-05-24

    Although solar radiation management (SRM) might play a role as an emergency geoengineering measure, its potential risks remain uncertain, and hence there are ethical and governance issues in the face of SRM's actual deployment. By using an integrated assessment model, we first present one possible methodology for evaluating the value arising from retaining an SRM option given the uncertainty of climate sensitivity, and also examine sensitivities of the option value to SRM's side effects (damages). Reflecting the governance challenges on immediate SRM deployment, we assume scenarios in which SRM could only be deployed with a limited degree of cooling (0.5 °C) only after 2050, when climate sensitivity uncertainty is assumed to be resolved and only when the sensitivity is found to be high (T2x = 4 °C). We conduct a cost-effectiveness analysis with constraining temperature rise as the objective. The SRM option value is originated from its rapid cooling capability that would alleviate the mitigation requirement under climate sensitivity uncertainty and thereby reduce mitigation costs. According to our estimates, the option value during 1990-2049 for a +2.4 °C target (the lowest temperature target level for which there were feasible solutions in this model study) relative to preindustrial levels were in the range between $2.5 and $5.9 trillion, taking into account the maximum level of side effects shown in the existing literature. The result indicates that lower limits of the option values for temperature targets below +2.4 °C would be greater than $2.5 trillion. PMID:27162346

  18. Binary sensitive systems based on A-ProOMe/AAc synthesized by gamma radiation

    International Nuclear Information System (INIS)

    Complete text of publication follows. Thermo and pH-responsive gels have received much interest in different fields of knowledge for their applications in drug delivery systems, controlled release systems for targeted delivery to specific areas of body and others. Poly(acryloyl-L-proline methyl ester) (A-ProOMe) exhibits a lower critical temperature (LCST) of 14 deg C and polyacrylic acid (PAAc) exhibits a critical pH response at about 4.5 deg C. In this work, three different systems containing (A-ProOMe) and (PAAc) were synthesized by gamma radiation; a) A-ProOMe grafted onto PAAc hydrogel 'comb type hydrogel'; b) radiation binary grafting of A-ProOMe and AAc onto PP by mutual irradiation method PP-g-AAc/A-ProOMe; and c) and binary grafting of those monomers in two step radiation method (PP-g- AAc)-g-(A-ProOMe). The characterization of the graft copolymers was examined by infrared (FTIR-ATR), and thermal analysis (TGA). Limit swelling behavior, pH sensitivity and Cu+2 uptake of different systems will be discussed. The authors wish to express their thanks to S. Castillo-Rojas, B. Leal, F. Garcia, and M. Cruz, from ICN-UNAM, for technical assistance. This work was supported by DGAPA-UNAM Mexico, Grant IN200108.

  19. Etoposide sensitizes CT26 colorectal adenocarcinoma to radiation therapy in BALB/c mice

    Institute of Scientific and Technical Information of China (English)

    Chia-Yuan Liu; Hui-Fen Liao; Tsang-En Wang; Shee-Chan Lin; Shou-Chuan Shih; Wen-Hsuing Chang; Yuh-Cheng Yang; Ching-Chung Lin; Yu-Jen Chen

    2005-01-01

    AIM: To investigate the combined effect of etoposide and radiation on CT26 colorectal adenocarcinoma implanted into BALB/c mice.METHODS: We evaluated the radiosensitizing effect of etoposide on CT26 colorectal adenocarcinoma in a syngeneic animal model. BALB/c mice were subcutaneously implanted with CT26 cells and divided into four groups:control (intra-peritoneal salinex2) group, etoposide (5 mg/kgintra-peritoneallyx2) group, radiation therapy (RT 5 Gyx2fractions) group, and combination therapy with etoposide (5 mg/kg intra-peritoneally 1 h before radiation) group.RESULTS: Tumor growth was significantly inhibited by RT and combination therapy. The effect of combination therapy was better than that of RT. No significant changes were noted in body weight, plasma alanine aminotransferase,or creatinine in any group. The leukocyte count significantly but transiently decreased in the RT and combination therapy groups, but not in the etoposide and control groups. There was no skin change or hair loss in the RT and combination therapy groups.CONCLUSION: Etoposide can sensitize CT26 colorectal adenocarcinoma in BALB/c mice to RT without significant toxicity.

  20. Aminopeptidase N (APN/CD13 inhibitor, Ubenimex, enhances radiation sensitivity in human cervical cancer

    Directory of Open Access Journals (Sweden)

    Nawa Akihiro

    2008-03-01

    Full Text Available Abstract Background Radiotherapy can be used to treat all stages of cervical cancer. For improving local control via radiotherapy, it is important to use additional antitumor agents. Aminopeptidase N (APN/CD13, a 150-kDa metalloproteinase, is a multifunctional cell surface aminopeptidase with ubiquitous expression. Recent studies have suggested that APN/CD13 plays an important role in tumor progression in several human malignancies. Methods We investigated whether the suppression of APN/CD13 using Ubenimex, an inhibitor of APN/CD13 activity, may affect tumor radiosensitivity in cervical cancer cells both in vitro and in vivo. Cell surface APN/CD13 activity in HeLa cells was calculated using alanine-p-nitroanilido as a substrate. For colony formation assays, single-dose radiation and/or Ubenimex were administered to each dish of HeLa cells, and these dishes were cultured for 14 days. Molecular changes of apoptosis were determined by Western blot. Apoptosis was evaluated by Annexin-V PI staining (flow cytometry analysis and the Tunel method. Moreover, we investigated the effect of combining Ubenimex and low-dose radiation on tumor growth using nude mice. Results We demonstrated that Ubenimex enhanced the effectiveness of radiotherapy, acting as a radiosensitizer both in vitro and in vivo. In colony formation assays, a significant decline in clonogenic survival was observed in Ubenimex-treated cells. Mice treated with a combination of radiation and Ubenimex showed a significant prolongation of the tumor-doubling time compared with the control, Ubenimex, or radiation-alone groups. We also showed that ubenimex enhanced radiation-induced apoptosis in vitro and in vivo. Conclusion Although further studies are needed, this report suggests that Ubeniemx acts as a radiosensitizer in cervical cancer treatment, and that the inhibition of APN/CD13 activity may represent a new approach for improving the therapeutic efficacy of radiotherapy for uterine

  1. Aminopeptidase N (APN)/CD13 inhibitor, Ubenimex, enhances radiation sensitivity in human cervical cancer

    International Nuclear Information System (INIS)

    Radiotherapy can be used to treat all stages of cervical cancer. For improving local control via radiotherapy, it is important to use additional antitumor agents. Aminopeptidase N (APN)/CD13, a 150-kDa metalloproteinase, is a multifunctional cell surface aminopeptidase with ubiquitous expression. Recent studies have suggested that APN/CD13 plays an important role in tumor progression in several human malignancies. We investigated whether the suppression of APN/CD13 using Ubenimex, an inhibitor of APN/CD13 activity, may affect tumor radiosensitivity in cervical cancer cells both in vitro and in vivo. Cell surface APN/CD13 activity in HeLa cells was calculated using alanine-p-nitroanilido as a substrate. For colony formation assays, single-dose radiation and/or Ubenimex were administered to each dish of HeLa cells, and these dishes were cultured for 14 days. Molecular changes of apoptosis were determined by Western blot. Apoptosis was evaluated by Annexin-V PI staining (flow cytometry analysis) and the Tunel method. Moreover, we investigated the effect of combining Ubenimex and low-dose radiation on tumor growth using nude mice. We demonstrated that Ubenimex enhanced the effectiveness of radiotherapy, acting as a radiosensitizer both in vitro and in vivo. In colony formation assays, a significant decline in clonogenic survival was observed in Ubenimex-treated cells. Mice treated with a combination of radiation and Ubenimex showed a significant prolongation of the tumor-doubling time compared with the control, Ubenimex, or radiation-alone groups. We also showed that ubenimex enhanced radiation-induced apoptosis in vitro and in vivo. Although further studies are needed, this report suggests that Ubeniemx acts as a radiosensitizer in cervical cancer treatment, and that the inhibition of APN/CD13 activity may represent a new approach for improving the therapeutic efficacy of radiotherapy for uterine cervical cancer

  2. Hyperthermia and PARP1-inhibition for sensitization of radiation and cisplatin treatment of cervical carcinoma cells

    International Nuclear Information System (INIS)

    Ionizing radiation causes single and double strand breaks (SSBs and DSBs). DSBs are among the most critical DNA lesions and can be repaired via either non-homologous end joining (NHEJ) in which PARP1, Ku70 and DNA-PKcs are important, or homologous recombination (HR), where BRCA2 and Rad51 are essential. Hyperthermia disturbs HR by temporary inactivation of BRCA2. Cisplatin disrupts NHEJ and PARP1-inhibitor blocks Poly-(ADP-ribose)polymerase- 1, which is important in SSB repair, NHEJ and backup-NHEJ. Our goal was to investigate the additional effectiveness of hyperthermia and PARP1-inhibition on radiation and/or cisplatin treatment. Cervical carcinoma cells (SiHa) were treated at different temperature levels levels (41.0-43.0℃, PARP1-inhibitor (100 μM; NU1025), gamma-irradiation doses (0-8 Gy) or cisplatin (1'R for 1 h). Clonogenic assays were carried out to measure survival and γH2AX staining was used to visualize DSBs. To elucidate mechanisms of action expression levels of DNA repair proteins BRCA2 and DNA-PKcs were investigated after 42.0℃ (1 h) using western blot. Combined hyperthermia and radiation resulted in an increased number of γH2AX foci as compared to radiation alone. Hyperthermia treatment in combination with cisplatin and PARP1 inhibitor and with radiation and PARP1 inhibitor significantly decreased cell survival. Western blot demonstrated a decreased expression of BRCA2 protein at 30 min after hyperthermia treatment. Adding PARP1-inhibitor significantly improves the effectiveness of combined hyperthermia radiotherapy and combined hyperthermia-cisplatin treatment on cervical carcinoma cells. Hyperthermia affects DNA-DSB repair as is indicated by increased γH2AX foci numbers and decreased BRCA2 expression. (author)

  3. Involvement of protease activation in modulating radiation-sensitivity of human cells

    International Nuclear Information System (INIS)

    Molecular mechanisms that supervise radiation-susceptibility of human cells are one of the important problems in molecular biology. We previously hypothesized that proteases may play a key role in cellular functions triggered by radiation as well as those in SOS functions of E. coli. We describe proteases activity induced immediately after UV (254-nm wavelength ultraviolet ray) and X-ray irradiation of cultured human cells. The activity was estimated by reaction in vitro, using enzyme preparations of cell lysates and 125I-fibrin as a substrate in the presence of plasminogen. Based on the previous findings that the activity of UV-induced proteases is specifically inhibited by antipain and enhanced by interferons, partial purification was performed, revealing a single activity peak of approximate 20 kDa on gel filtration chromatography. This activity seemed to be involved in the radio-resistance of cells against UV, because the activation correlated with increased resistance of cells to UV cell-killing. Moreover, the activation was also observed in association with hypomutable change of cells mutagenized with ethylmethanesulfonate and cells pretreated with human interferons prior to UV irradiation, when UV-induced mutagenicity was estimated by detection of K-ras codon 12 mutations. However, human RSa cells, with high sensitivity to cell-killing and mutagenicity of X-ray, showed increased levels of proteases activity immediately after X-ray irradiation. Therefore, it seems likely that proteases are activated by different ionizing or non-ionizing radiation, and that the proteases may play radio -sensitive or -protective roles in human cells. (author)

  4. Sensitivity of human cells defective of DNA repair enzyme genes to radiation and medical agents

    International Nuclear Information System (INIS)

    Homologous recombination and non-homologous end-joining (NHEJ) are the known mechanisms of repairing DNA with double strand break (DSB) yielded by radiation and cell-cycle independent NHEJ is thought to be major in higher eukaryotes. Recognized now are 7 proteins like Artemis and XRCC4 concerned in NHEJ, but little is known for functions of those proteins in human cells. Authors have developed a method to destroy the specific gene by targeting for the study of the responses to DNA damage in human Artemis-/- and XRCC4-/- cells, which is described in this paper. Parent cell strain is a human colorectal cancer-derived epithelial HCT116, and those defective cells are obtained by targeting with puromycin and neomycin resistant vectors. Their sensitivities to X-ray (0.6 Gy/min), to etoposide and to other anti-cancers are examined by survival vs dose; and the relationship between the sensitivity to damaged DNA stress and DSB production is tested by chromosome aberration frequency and by γH22AX focus formation (a measure of DSB yield) after X-exposure. Results obtained show the important role of Artemis and XRCC4 also in human cell DSB response. With reactive oxygen species (H2O2), those cells are further used in similar experiments to above, which suggesting a different mechanism of DSB induction by H2O2 from that by radiation. Other genes than the two here in NHEJ will be investigated in future with gene targeting techniques for systematic, molecular elucidation of radiation effects in humans. (K.T.)

  5. Do Case Rates Affect Physicians' Clinical Practice in Radiation Oncology?: An Observational Study

    Science.gov (United States)

    Loy, Bryan A.; Shkedy, Clive I.; Powell, Adam C.; Happe, Laura E.; Royalty, Julie A.; Miao, Michael T.; Smith, Gary L.; Long, James W.; Gupta, Amit K.

    2016-01-01

    Case rate payments combined with utilization monitoring may have the potential to improve the quality of care by reducing over and under-treatment. Thus, a national managed care organization introduced case rate payments at one multi-site radiation oncology provider while maintaining only fee-for-service payments at others. This study examined whether the introduction of the payment method had an effect on radiation fractions administered when compared to clinical guidelines. The number of fractions of radiation therapy delivered to patients with bone metastases, breast, lung, prostate, and skin cancer was assessed for concordance with clinical guidelines. The proportion of guideline-based care ascertained from the payer's claims database was compared before (2011) and after (2013) the payment method introduction using relative risks (RR). After the introduction of case rates, there were no significant changes in guideline-based care in breast, lung, and skin cancer; however, patients with bone metastases and prostate cancer were significantly more likely to have received guideline-based care (RR = 2.0 and 1.1, respectively, p<0.05). For the aggregate of all cancers, the under-treatment rate significantly declined (p = 0.008) from 4% to 0% after the introduction of case rate payments, while the over-treatment rate remained steady at 9%, with no significant change (p = 0.20). These findings suggest that the introduction of case rate payments did not adversely affect the rate of guideline-based care at the provider examined. Additional research is needed to isolate the effect of the payment model and assess implications in other populations. PMID:26870963

  6. Do Case Rates Affect Physicians' Clinical Practice in Radiation Oncology?: An Observational Study.

    Directory of Open Access Journals (Sweden)

    Bryan A Loy

    Full Text Available Case rate payments combined with utilization monitoring may have the potential to improve the quality of care by reducing over and under-treatment. Thus, a national managed care organization introduced case rate payments at one multi-site radiation oncology provider while maintaining only fee-for-service payments at others. This study examined whether the introduction of the payment method had an effect on radiation fractions administered when compared to clinical guidelines. The number of fractions of radiation therapy delivered to patients with bone metastases, breast, lung, prostate, and skin cancer was assessed for concordance with clinical guidelines. The proportion of guideline-based care ascertained from the payer's claims database was compared before (2011 and after (2013 the payment method introduction using relative risks (RR. After the introduction of case rates, there were no significant changes in guideline-based care in breast, lung, and skin cancer; however, patients with bone metastases and prostate cancer were significantly more likely to have received guideline-based care (RR = 2.0 and 1.1, respectively, p<0.05. For the aggregate of all cancers, the under-treatment rate significantly declined (p = 0.008 from 4% to 0% after the introduction of case rate payments, while the over-treatment rate remained steady at 9%, with no significant change (p = 0.20. These findings suggest that the introduction of case rate payments did not adversely affect the rate of guideline-based care at the provider examined. Additional research is needed to isolate the effect of the payment model and assess implications in other populations.

  7. Altered metaphase chromosome structure in xrs-5 cells is not related to its radiation sensitivity or defective DNA break rejoining

    International Nuclear Information System (INIS)

    The Chinese hamster ovary (CHO) cell line xrs-5 is a radiation-sensitive derivative of CHO-K1 cells. The xrs-5 cells have a defect in DNA double-strand break rejoining and show alterations in chromosome structure and nuclear morphology. The relationship between radiation sensitivity and metaphase chromosome morphology was examined in 12 'revertant' xrs-5 clones isolated following treatment with 5-azacytidine. Nine of the clones were radioresistant while the other three retained xrs-5-like radiation sensitivity. Chromosome morphology reverted to CHO-K1-like characteristics in three of the radioresistant clones and one of the radiosensitive clones suggesting that the over-condensed metaphase chromosome morphology of xrs-5 cells does not underlie its radiation sensitivity. Radiation sensitivity did correlate with DNA double-strand break rejoining ability. The radioresistant clones showing the over-condensed xrs-5-like chromosome morphology were also slightly more sensitive to the topoisomerase II inhibitor etoposide (VP-16) than CHO-K1, suggesting that the over-condensed morphology might be due to alterations in the phosphorylation of chromatin proteins

  8. Factors affecting the radiation dose to the lens of the eye during cardiac catheterization procedures

    International Nuclear Information System (INIS)

    Concern has been expressed about relatively high radiation doses to the lens of the eye received by the operator during cardiac catheterization studies. A study was undertaken to assess occupational doses received by cardiologists and to examine the factors that affect the individual's eye dose. Eighteen cardiologists working in five catheterization laboratories at three centres were included in the study. Their eye doses, workload and individual study details were monitored at each centre. Operating dose rates and scattered radiation were also measured for each unit to compare equipment performance. The study demonstrated that the relationships between the cardiologist's eye dose and factors such as the dose efficiency of the X-ray equipment, scattered dose rates, examination protocols and workload are complex and vary from centre to centre. Because of these variations general workload limits may be inaccurate and should only be used for general guidance when no direct measurements are available. Such limits should be verified by local measurements as soon as is practical. (Author)

  9. Enhanced radiation sensitivity and radiation recall dermatitis (RRD after hypericin therapy – case report and review of literature

    Directory of Open Access Journals (Sweden)

    Schäfer Christof

    2006-09-01

    Full Text Available Abstract Background Modern radiotherapy (RT reduces the side effects at organ at risk. However, skin toxicity is still a major problem in many entities, especially head and neck cancer. Some substances like chemotherapy provide a risk of increased side effects or can induce a "recall phenomenon" imitating acute RT-reactions months after RT. Moreover, some phototoxic drugs seem to enhance side effects of radiotherapy while others do not. We report a case of "radiation recall dermatitis" (RRD one year after RT as a result of taking hypericin (St. John's wort. Case report A 65 year old man with completely resected squamous cell carcinoma of the epiglottis received an adjuvant locoregional RT up to a dose of 64.8 Gy. The patient took hypericin during and months after RT without informing the physician. During radiotherapy the patient developed unusual intensive skin reactions. Five months after RT the skin was completely bland at the first follow up. However, half a year later the patient presented erythema, but only within the area of previously irradiated skin. After local application of a steroid cream the symptoms diminished but returned after the end of steroid therapy. The anamnesis disclosed that the patient took hypericin because of depressive mood. We recommended to discontinue hypericin and the symptoms disappeared afterward. Conclusion Several drugs are able to enhance skin toxicity of RT. Furthermore, the effect of RRD is well known especially for chemotherapy agents such as taxans. However, the underlying mechanisms are not known in detail so far. Moreover, it is unknown whether photosensitising drugs can also be considered to increase radiation sensitivity and whether a recall phenomenon is possible. The first report of a hypericin induced RRD and review of the literature are presented. In clinical practise many interactions between drugs and radiotherapy were not noticed and if registered not published. We recommend to ask especially

  10. Enhanced radiation sensitivity and radiation recall dermatitis (RRD) after hypericin therapy – case report and review of literature

    International Nuclear Information System (INIS)

    Modern radiotherapy (RT) reduces the side effects at organ at risk. However, skin toxicity is still a major problem in many entities, especially head and neck cancer. Some substances like chemotherapy provide a risk of increased side effects or can induce a 'recall phenomenon' imitating acute RT-reactions months after RT. Moreover, some phototoxic drugs seem to enhance side effects of radiotherapy while others do not. We report a case of 'radiation recall dermatitis' (RRD) one year after RT as a result of taking hypericin (St. John's wort). A 65 year old man with completely resected squamous cell carcinoma of the epiglottis received an adjuvant locoregional RT up to a dose of 64.8 Gy. The patient took hypericin during and months after RT without informing the physician. During radiotherapy the patient developed unusual intensive skin reactions. Five months after RT the skin was completely bland at the first follow up. However, half a year later the patient presented erythema, but only within the area of previously irradiated skin. After local application of a steroid cream the symptoms diminished but returned after the end of steroid therapy. The anamnesis disclosed that the patient took hypericin because of depressive mood. We recommended to discontinue hypericin and the symptoms disappeared afterward. Several drugs are able to enhance skin toxicity of RT. Furthermore, the effect of RRD is well known especially for chemotherapy agents such as taxans. However, the underlying mechanisms are not known in detail so far. Moreover, it is unknown whether photosensitising drugs can also be considered to increase radiation sensitivity and whether a recall phenomenon is possible. The first report of a hypericin induced RRD and review of the literature are presented. In clinical practise many interactions between drugs and radiotherapy were not noticed and if registered not published. We recommend to ask especially for complementary or alternative

  11. Exquisite sensitivity of dendritic cells to ultraviolet radiation and temperature changes

    International Nuclear Information System (INIS)

    Recent data suggest that dendritic cells (DC) are the critical passenger leukocytes in allograft rejection. Moreover, previous studies suggest that ultraviolet radiation (UVR) abrogates many in vivo and in vitro immune responses in which DC function as potent accessory cells (AC); however, the mechanism(s) underlying the suppressive effect of UVR on these responses is unclear. To address this mechanism, the hypothesis was tested that loss of DC viability (hence function) accounts for the suppressive effect of UVR on these responses. To this end, in vitro effects of UVR on murine splenic DC viability were addressed using two types of UVR (ultraviolet B [UVB] and ultraviolet C [UVC]) over a UVR dose range of 0-864 J/m2. DC viability was exquisitely sensitive to UVR when compared with other AC populations and UVC was 4-fold more effective in decreasing DC viability than UVB when doses of equal energy were compared. It was found that both UVR types induced marked decreases in DC viability beginning 4-6 hr post-UVR-treatment, that UVR- and non-UVR-induced death were temperature-dependent, and that decreases in DC viability induced by UVR were compatible with interphase death. Our findings indicate that DC are sensitive to temperature changes and exquisitely sensitive to UVR, and suggest that UVR-induced abrogation of murine immune responses is likely attributable to UVR-induced DC death

  12. Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties

    DEFF Research Database (Denmark)

    Madsen, Jakob Torp; Vogel, Stefan; Johansen, Jeanne Duus;

    2011-01-01

    Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens...... dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed...

  13. Encapsulating contact allergens in liposomes, ethosomes, and polycaprolactone may affect their sensitizing properties

    DEFF Research Database (Denmark)

    Madsen, Jakob Torp; Vogel, Stefan; Johansen, Jeanne Duus;

    2011-01-01

    Attempts to improve formulation of topical products are a continuing process and the development of micro- and nanovesicular systems as well as polymeric microparticles has led to marketing of topical drugs and cosmetics using these technologies. Encapsulation of some well-known contact allergens...... dichromate compared with control solutions. However, encapsulating the lipophilic contact allergen dinitrochlorobenzene (DNCB) in polycaprolactone reduced the sensitizing capacity to 1211 ± 449 compared with liposomes (7602 ± 2658) and in acetone:olive oil (4:1) (5633 ± 666). The same trend was observed...

  14. X-ray survival characteristics and genetic analysis for nine Saccharomyces deletion mutants that show altered radiation sensitivity.

    Science.gov (United States)

    Game, John C; Williamson, Marsha S; Baccari, Clelia

    2005-01-01

    The availability of a genome-wide set of Saccharomyces deletion mutants provides a chance to identify all the yeast genes involved in DNA repair. Using X rays, we are screening these mutants to identify additional genes that cause increased sensitivity to the lethal effects of ionizing radiation. For each mutant identified as sensitive, we are confirming that the sensitivity phenotype cosegregates with the deletion allele and are obtaining multipoint survival-vs.-dose assays in at least one homozygous diploid and two haploid strains. We present data for deletion mutants involving the genes DOT1, MDM20, NAT3, SPT7, SPT20, GCN5, HFI1, DCC1, and VID21/EAF1 and discuss their potential roles in repair. Eight of these genes cause a clear radiation-sensitive phenotype when deleted, but the ninth, GCN5, results in at most a borderline phenotype. None of the deletions confer substantial sensitivity to ultraviolet radiation, although one or two may confer marginal sensitivity. The DOT1 gene is of interest because its only known function is to methylate one lysine residue in the core of the histone H3 protein. We find that histone H3 mutants (supplied by K. Struhl) in which this residue is replaced by other amino acids are also X-ray sensitive, which confirms that methylation of the lysine-79 residue is required for effective repair of radiation damage. PMID:15371366

  15. X-ray survival characteristics and genetic analysis for nine saccharomyces deletion mutants that show altered radiation sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Game, John C.; Williamson, Marsha S.; Baccari, Clelia

    2004-01-07

    The availability of a genome-wide set of Saccharomyces deletion mutants provides a chance to identify all the yeast genes involved in DNA repair. Using X-rays, we are screening these mutants to identify additional genes that show increased sensitivity to the lethal effects of ionizing radiation. For each mutant identified as sensitive, we are confirming that the sensitivity phenotype co-segregates with the deletion allele and are obtaining multipoint survival-versus-dose assays in at least two haploid and one homozygous diploid strains. We present data for deletion mutants involving the genes DOT1, MDM20, NAT3, SPT7, SPT20, GCN5, HFI1, DCC1 and VID21/EAF1, and discuss their potential roles in repair. Eight of these genes have a clear radiation-sensitive phenotype when deleted, but the ninth, GCN5, has at most a borderline phenotype. None of the deletions confer substantial sensitivity to ultra-violet radiation, although one or two may confer marginal sensitivity. The DOT1 gene is of interest because its only known function is to methylate one lysine residue in the core of the histone H3 protein. We find that histone H3 mutants (supplied by K. Struhl) in which this residue is replaced by other amino-acids are also X-ray sensitive, seeming to confirm that methylation of the lysine-79 residue is required for effective repair of radiation damage.

  16. Sensitivity of planktonic and biofilm-associated Aeromonas spp. to ionizing radiation

    International Nuclear Information System (INIS)

    Aeromonas cells, on radiation sensitivity is isolate specific. (author)

  17. Genome-wide functional screen identifies a compendium of genes affecting sensitivity to tamoxifen

    Science.gov (United States)

    Mendes-Pereira, Ana M.; Sims, David; Dexter, Tim; Fenwick, Kerry; Assiotis, Ioannis; Kozarewa, Iwanka; Mitsopoulos, Costas; Hakas, Jarle; Zvelebil, Marketa; Lord, Christopher J.; Ashworth, Alan

    2012-01-01

    Therapies that target estrogen signaling have made a very considerable contribution to reducing mortality from breast cancer. However, resistance to tamoxifen remains a major clinical problem. Here we have used a genome-wide functional profiling approach to identify multiple genes that confer resistance or sensitivity to tamoxifen. Combining whole-genome shRNA screening with massively parallel sequencing, we have profiled the impact of more than 56,670 RNA interference reagents targeting 16,487 genes on the cellular response to tamoxifen. This screen, along with subsequent validation experiments, identifies a compendium of genes whose silencing causes tamoxifen resistance (including BAP1, CLPP, GPRC5D, NAE1, NF1, NIPBL, NSD1, RAD21, RARG, SMC3, and UBA3) and also a set of genes whose silencing causes sensitivity to this endocrine agent (C10orf72, C15orf55/NUT, EDF1, ING5, KRAS, NOC3L, PPP1R15B, RRAS2, TMPRSS2, and TPM4). Multiple individual genes, including NF1, a regulator of RAS signaling, also correlate with clinical outcome after tamoxifen treatment. PMID:21482774

  18. Broadband noise exposure does not affect hearing sensitivity in big brown bats (Eptesicus fuscus).

    Science.gov (United States)

    Simmons, Andrea Megela; Hom, Kelsey N; Warnecke, Michaela; Simmons, James A

    2016-04-01

    In many vertebrates, exposure to intense sounds under certain stimulus conditions can induce temporary threshold shifts that reduce hearing sensitivity. Susceptibility to these hearing losses may reflect the relatively quiet environments in which most of these species have evolved. Echolocating big brown bats (Eptesicus fuscus) live in extremely intense acoustic environments in which they navigate and forage successfully, both alone and in company with other bats. We hypothesized that bats may have evolved a mechanism to minimize noise-induced hearing losses that otherwise could impair natural echolocation behaviors. The hearing sensitivity of seven big brown bats was measured in active echolocation and passive hearing tasks, before and after exposure to broadband noise spanning their audiometric range (10-100 kHz, 116 dB SPL re. 20 µPa rms, 1 h duration; sound exposure level 152 dB). Detection thresholds measured 20 min, 2 h or 24 h after exposure did not vary significantly from pre-exposure thresholds or from thresholds in control (sham exposure) conditions. These results suggest that big brown bats may be less susceptible to temporary threshold shifts than are other terrestrial mammals after exposure to similarly intense broadband sounds. These experiments provide fertile ground for future research on possible mechanisms employed by echolocating bats to minimize hearing losses while orienting effectively in noisy biological soundscapes. PMID:27030779

  19. Improved Intratumoral Oxygenation Through Vascular Normalization Increases Glioma Sensitivity to Ionizing Radiation

    International Nuclear Information System (INIS)

    Purpose: Ionizing radiation, an important component of glioma therapy, is critically dependent on tumor oxygenation. However, gliomas are notable for areas of necrosis and hypoxia, which foster radioresistance. We hypothesized that pharmacologic manipulation of the typically dysfunctional tumor vasculature would improve intratumoral oxygenation and, thus, the antiglioma efficacy of ionizing radiation. Methods and Materials: Orthotopic U87 xenografts were treated with either continuous interferon-β (IFN-β) or bevacizumab, alone, or combined with cranial irradiation (RT). Tumor growth was assessed by quantitative bioluminescence imaging; the tumor vasculature using immunohistochemical staining, and tumor oxygenation using hypoxyprobe staining. Results: Both IFN-β and bevaziumab profoundly affected the tumor vasculature, albeit with different cellular phenotypes. IFN-β caused a doubling in the percentage of area of perivascular cell staining, and bevacizumab caused a rapid decrease in the percentage of area of endothelial cell staining. However, both agents increased intratumoral oxygenation, although with bevacizumab, the effect was transient, being lost by 5 days. Administration of IFN-β or bevacizumab before RT was significantly more effective than any of the three modalities as monotherapy or when RT was administered concomitantly with IFN-β or bevacizumab or 5 days after bevacizumab. Conclusion: Bevacizumab and continuous delivery of IFN-β each induced significant changes in glioma vascular physiology, improving intratumoral oxygenation and enhancing the antitumor activity of ionizing radiation. Additional investigation into the use and timing of these and other agents that modify the vascular phenotype, combined with RT, is warranted to optimize cytotoxic activity.

  20. Radiation induced bystander effects in modification of cellular radio-sensitivity in human cancer cells

    International Nuclear Information System (INIS)

    Radiation-induced Bystander Effect is manifestation of radiation effects in non-irradiated cells in the population. The phenomenon may have significant implication in risk of radiation induced cancer incidence and outcome of cancer radiotherapy. To understand the bystander interaction in tumor cells, we have studied secretion of diffusible factors from control and irradiated tumor cells of different origin. Our results showed a good correlation between magnitude of secretion of diffusible factors and survival of tumor cells. These diffusible factors are shown to affect proliferation and survival of tumor cells involving regulation of kinases and genes/proteins involved in apoptotic machinery. Our experiments using pharmacological inhibitors showed involvement of activating transcription factor 2 (ATF-2) signaling in survival of tumor cells after treatment with diffusible factors. These factors seem to be involved in exerting radio-resistance in tumor cells. Furthermore, in proton microbeam irradiation studies showed induction of double strand break measured as gH2AX foci in human lung carcinoma cells, which was found to propagate to bystander tumor cells during post-irradiation incubation. Implication of these observations in outcome of cancer radiotherapy scenario would be discussed. (author)

  1. Materials-of-Construction Radiation Sensitivity for a Fission Surface Power Convertor

    Science.gov (United States)

    Bowman, Cheryl L.; Geng, Steven M.; Niedra, Janis M.; Sayir, Ali; Shin, Eugene E.; Sutter, James K.; Thieme, Lanny G.

    2007-01-01

    A fission reactor combined with a free-piston Stirling convertor is one of many credible approaches for producing electrical power in space applications. This study assumes dual-opposed free-piston Stirling engines/linear alternators that will operate nominally at 825 K hot-end and 425 K cold-end temperatures. The baseline design options, temperature profiles, and materials of construction discussed here are based on historical designs as well as modern convertors operating at lower power levels. This notional design indicates convertors primarily made of metallic components that experience minimal change in mechanical properties for fast neutron fluences less than 10(sup 20) neutrons per square centimeter. However, these radiation effects can impact the magnetic and electrical properties of metals at much lower fluences than are crucial for mechanical property integrity. Moreover, a variety of polymeric materials are also used in common free-piston Stirling designs for bonding, seals, lubrication, insulation and others. Polymers can be affected adversely by radiation doses as low as 10(sup 5) - 10(sup 10) rad. Additionally, the absorbing dose rate, radiation hardness, and the resulting effect (either hardening or softening) varies depending on the nature of the particular polymer. The classes of polymers currently used in convertor fabrication are discussed along possible substitution options. Thus, the materials of construction of prototypic Stirling convertor engines have been considered and the component materials susceptible to damage at the lowest neutron fluences have been identified.

  2. Radiation Sensitivity in a Preclinical Mouse Model of Medulloblastoma Relies on the Function of the Intrinsic Apoptotic Pathway.

    Science.gov (United States)

    Crowther, Andrew J; Ocasio, Jennifer K; Fang, Fang; Meidinger, Jessica; Wu, Jaclyn; Deal, Allison M; Chang, Sha X; Yuan, Hong; Schmid, Ralf; Davis, Ian; Gershon, Timothy R

    2016-06-01

    While treatments that induce DNA damage are commonly used as anticancer therapies, the mechanisms through which DNA damage produces a therapeutic response are incompletely understood. Here we have tested whether medulloblastomas must be competent for apoptosis to be sensitive to radiotherapy. Whether apoptosis is required for radiation sensitivity has been controversial. Medulloblastoma, the most common malignant brain tumor in children, is a biologically heterogeneous set of tumors typically sensitive to radiation and chemotherapy; 80% of medulloblastoma patients survive long-term after treatment. We used functional genetic studies to determine whether the intrinsic apoptotic pathway is required for radiation to produce a therapeutic response in mice with primary, Shh-driven medulloblastoma. We found that cranial radiation extended the survival of medulloblastoma-bearing mice and induced widespread apoptosis. Expression analysis and conditional deletion studies showed that Trp53 (p53) was the predominant transcriptional regulator activated by radiation and was strictly required for treatment response. Deletion of Bax, which blocked apoptosis downstream of p53, was sufficient to render tumors radiation resistant. In apoptosis-incompetent, Bax-deleted tumors, radiation activated p53-dependent transcription without provoking cell death and caused two discrete populations to emerge. Most radiated tumor cells underwent terminal differentiation. Perivascular cells, however, quickly resumed proliferation despite p53 activation, behaved as stem cells, and rapidly drove recurrence. These data show that radiation must induce apoptosis in tumor stem cells to be effective. Mutations that disable the intrinsic apoptotic pathways are sufficient to impart radiation resistance. We suggest that medulloblastomas are typically sensitive to DNA-damaging therapies, because they retain apoptosis competence. Cancer Res; 76(11); 3211-23. ©2016 AACR. PMID:27197166

  3. Radiation use-efficiency of field beans as affected by soil phosphorus management

    International Nuclear Information System (INIS)

    A simple approach to modeling dry matter production is based on the assumption that radiation‐use efficiency (RUE), which is the amount of dry weight produced per unit of intercepted photosynthetically active radiation (IPAR), is relatively constant for crops adequately supplied with water and nutrients. Recent evidences, however, indicate that RUE is not constant but is strongly affected by environment. Soil stresses also appear to affect RUE but few responses have been documented. Growth analysis data from a field experiment were used to compute RUE of field beans grown at differential phosphorus (P) regimes. The main objective of this study was to assess the effects of soil P management on RUE. Applied P rates significantly increased RUE with values ranging from 0.86 g M/J at 0 kg P/ha to 1.09 g M/J at 200 kg P/ha. The relationship between total dry matter and cumulative EPAR was linear at low P regimes but resembled a curvilinear relationship at high P regimes. The RUE of beans under high soil P regimes was not constant but decreased over time. (author)

  4. Characterization of dose-dependent Young's modulus for a radiation-sensitive polymer gel

    International Nuclear Information System (INIS)

    Radiation-sensitive polymer gels for clinical dosimetry have been intensively investigated with magnetic resonance imaging (MRI) because the transversal magnetic relaxation time is dependent on irradiation dose. MRI is expensive and not easily available in most clinics. For this reason, low-cost, quick and easy-to-use potential alternatives such as optical computed tomography (CT), x-ray CT or ultrasound attenuation CT have also been studied by others. Here, we instead evaluate the dose dependence of the elastic material property, Young's modulus and the dose response of the viscous relaxation of radiation-sensitive gels to discuss their potential for dose imaging. Three batches of a radiation-sensitive polymer gel (MAGIC gel) samples were homogeneously irradiated to doses from 0 Gy to 45.5 Gy. Young's modulus was computed from the measured stress on the sample surface and the strain applied to the sample when compressing it axially, and the viscous relaxation was determined from the stress decay under sustained compression. The viscous relaxation was found not to change significantly with dose. However, Young's modulus was dose dependent; it approximately doubled in the gels between 0 Gy and 20 Gy. By fitting a second-order polynomial to the Young's modulus-versus-dose data, 99.4% of the variance in Young's modulus was shown to be associated with the change in dose. The precision of the gel production, irradiation and Young's modulus measurement combined was found to be 4% at 2 Gy and 3% at 20 Gy. Potential sources of measurement error, such as those associated with the boundary conditions in the compression measurement, inhomogeneous polymerization, temperature (up to 1% error) and the evaporation of water from the sample (up to 1% error), were estimated and discussed. It was concluded that Young's modulus could be used for dose determination. Imaging techniques such as elastography may help to achieve this if they can provide a local measurement of Young

  5. Mesenchymal stem cells are sensitive to treatment with kinase inhibitors and ionizing radiation

    International Nuclear Information System (INIS)

    Mesenchymal stem cells (MSCs) can regenerate damaged tissues and may therefore be of importance for normal tissue repair after cancer treatment. Small molecule receptor kinase inhibitors (RKIs) have recently been introduced into cancer treatment. However, the influence of these drugs - particularly in combination with radiotherapy - on the survival of MSCs is largely unknown. The sensitivity of human primary MSCs from healthy volunteers and primary human fibroblast cells to small molecule kinase inhibitors of the vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and transforming growth factor β (TGFβ) receptors, as well to inhibitors of c-Kit, was examined in combination with ionizing radiation (IR); cell survival and proliferation were assessed. Expression patterns of different kinase receptors and ligands were investigated using gene arrays. MSCs were highly sensitive to the tyrosine kinase inhibitors SU14816 (imatinib) and SU11657 (sunitinib), but showed only moderate sensitivity to the selective TGFβ receptor 1 inhibitor LY2109761. Primary adult human fibroblasts were comparably resistant to all three inhibitors. The addition of IR had an additive or supra-additive effect in the MSCs, but this was not the case for differentiated fibroblasts. Proliferation was markedly reduced in MSCs following kinase inhibition, both with and without IR. Gene expression analysis revealed high levels of the PDGF α and β receptors, and lower levels of the TGFβ receptor 2 and Abl kinase. IR did not alter the expression of kinase receptors or their respective ligands in either MSCs or adult fibroblasts. These data show that MSCs are highly sensitive to RKIs and combination treatments incorporating IR. Expression analyses suggest that high levels of PDGF receptors may contribute to this effect. (orig.)

  6. The effect of free radical inhibitor on the sensitized radiation crosslinking and thermal processing stabilization of polyurethane shape memory polymers

    International Nuclear Information System (INIS)

    The effects of free radical inhibitor on the electron beam crosslinking and thermal processing stabilization of novel radiation crosslinkable polyurethane shape memory polymers (SMPs) blended with acrylic radiation sensitizers have been determined. The SMPs in this study possess novel processing capabilities—that is, the ability to be melt processed into complex geometries as thermoplastics and crosslinked in a secondary step using electron beam irradiation. To increase susceptibility to radiation crosslinking, the radiation sensitizer pentaerythritol triacrylate (PETA) was solution blended with thermoplastic polyurethane SMPs made from 2-butene-1,4-diol and trimethylhexamethylene diisocyanate (TMHDI). Because the thermoplastic melt processing methods such as injection molding are often carried out at elevated temperatures, sensitizer thermal instability is a major processing concern. Free radical inhibitor can be added to provide thermal stabilization; however, inhibitor can also undesirably inhibit radiation crosslinking. In this study, we quantified both the thermal stabilization and radiation crosslinking inhibition effects of the inhibitor 1,4-benzoquinone (BQ) on polyurethane SMPs blended with PETA. Sol/gel analysis of irradiated samples showed that the inhibitor had little to no inverse effects on gel fraction at concentrations of 0–10,000 ppm, and dynamic mechanical analysis showed only a slight negative correlation between BQ composition and rubbery modulus. The 1,4-benzoquinone was also highly effective in thermally stabilizing the acrylic sensitizers. The polymer blends could be heated to 150 °C for up to 5 h or to 125 °C for up to 24 h if stabilized with 10,000 ppm BQ and could also be heated to 125 °C for up to 5 h if stabilized with 1000 ppm BQ without sensitizer reaction occurring. We believe this study provides significant insight into methods for manipulation of the competing mechanisms of radiation crosslinking and thermal stabilization of

  7. I feel you: the design and evaluation of a domotic affect-sensitive spoken conversational agent.

    Science.gov (United States)

    Lutfi, Syaheerah Lebai; Fernández-Martínez, Fernando; Lorenzo-Trueba, Jaime; Barra-Chicote, Roberto; Montero, Juan Manuel

    2013-01-01

    We describe the work on infusion of emotion into a limited-task autonomous spoken conversational agent situated in the domestic environment, using a need-inspired task-independent emotion model (NEMO). In order to demonstrate the generation of affect through the use of the model, we describe the work of integrating it with a natural-language mixed-initiative HiFi-control spoken conversational agent (SCA). NEMO and the host system communicate externally, removing the need for the Dialog Manager to be modified, as is done in most existing dialog systems, in order to be adaptive. The first part of the paper concerns the integration between NEMO and the host agent. The second part summarizes the work on automatic affect prediction, namely, frustration and contentment, from dialog features, a non-conventional source, in the attempt of moving towards a more user-centric approach. The final part reports the evaluation results obtained from a user study, in which both versions of the agent (non-adaptive and emotionally-adaptive) were compared. The results provide substantial evidences with respect to the benefits of adding emotion in a spoken conversational agent, especially in mitigating users' frustrations and, ultimately, improving their satisfaction. PMID:23945740

  8. I Feel You: The Design and Evaluation of a Domotic Affect-Sensitive Spoken Conversational Agent

    Directory of Open Access Journals (Sweden)

    Juan Manuel Montero

    2013-08-01

    Full Text Available We describe the work on infusion of emotion into a limited-task autonomous spoken conversational agent situated in the domestic environment, using a need-inspired task-independent emotion model (NEMO. In order to demonstrate the generation of affect through the use of the model, we describe the work of integrating it with a natural-language mixed-initiative HiFi-control spoken conversational agent (SCA. NEMO and the host system communicate externally, removing the need for the Dialog Manager to be modified, as is done in most existing dialog systems, in order to be adaptive. The first part of the paper concerns the integration between NEMO and the host agent. The second part summarizes the work on automatic affect prediction, namely, frustration and contentment, from dialog features, a non-conventional source, in the attempt of moving towards a more user-centric approach. The final part reports the evaluation results obtained from a user study, in which both versions of the agent (non-adaptive and emotionally-adaptive were compared. The results provide substantial evidences with respect to the benefits of adding emotion in a spoken conversational agent, especially in mitigating users’ frustrations and, ultimately, improving their satisfaction.

  9. Gene expression profiling of human dermal fibroblasts exposed to bleomycin sulphate does not differentiate between radiation sensitive and control patients

    International Nuclear Information System (INIS)

    Gene expression profiling of the transcriptional response of human dermal fibroblasts to in vitro radiation has shown promise as a predictive test of radiosensitivity. This study tested if treatment with the radiomimetic drug bleomycin sulphate could be used to differentiate radiation sensitive patients and controls in patients who had previously received radiotherapy for early breast cancer. Eight patients who developed marked late radiation change assessed by photographic breast appearance and 8 matched patients without any change were selected from women entered in a prospective randomised trial of breast radiotherapy fractionation. Gene expression profiling of primary skin fibroblasts exposed in vitro to bleomycin sulphate and mock treated fibroblast controls was performed. 973 genes were up-regulated and 923 down-reguated in bleomycin sulphate treated compared to mock treated control fibroblasts. Gene ontology analysis revealed enriched groups were cellular localisation, apoptosis, cell cycle and DNA damage response for the deregulated genes. No transcriptional differences were identified between fibroblasts from radiation sensitive cases and control patients; subgroup analysis using cases exhibiting severe radiation sensitivity or with high risk alleles present in TGF β1 also showed no difference. The transcriptional response of human dermal fibroblasts to bleomycin sulphate has been characterised. No differences between clinically radiation sensitive and control patients were detected using this approach

  10. Radiation sensitivity of foodborne pathogens in meat byproducts with different packaging

    Science.gov (United States)

    Yong, Hae In; Kim, Hyun-Joo; Nam, Ki Chang; Kwon, Joong Ho; Jo, Cheorun

    2015-10-01

    The aim of this study was to determine radiation sensitivity of Escherichia coli O157:H7 and Listeria monocytogenes in edible meat byproducts. Seven beef byproducts (heart, liver, lung, lumen, omasum, large intestine, and small intestine) and four pork byproducts (heart, large intestine, liver, and small intestine) were used. Electron beam irradiation significantly reduced the numbers of pathogenic microorganisms in meat byproducts and no viable cells were detected in both aerobically- and vacuum-packaged samples irradiated at 4 kGy. Meat byproducts packed under vacuum had higher D10 value than the ones packed aerobically. No significant difference was observed between the D10 values of E. coli O157:H7 and L. monocytogenes inoculated in either aerobically or vacuum packaged samples. These results suggest that low-dose electron beam irradiation can significantly decrease microbial numbers and reduce the risk of meat byproduct contamination by the foodborne pathogens.

  11. Radiation synthesis and characterization of stimuli-sensitive chitosan-polyvinyl pyrrolidone hydrogels

    International Nuclear Information System (INIS)

    Novel cationic hydrogels were synthesized by γ-irradiation copolymerization of chitosan and polyvinyl pyrrolidone (PVP). The synthesis regularities and the swelling behaviour of hydrogels have been studied. It was shown that increasing of PVP concentration in feed composition also as radiation dose accompanied of increase of yield of gel fraction and decrease of swelling degree. At dose more than 3.5 kGy increasing of swelling degree and decreasing of gel fraction yield have been observed. It was shown that the hydrogels exhibit pH-sensitive behaviour in aqueous solution. In solutions of sodium dodecyl sulfate (SDS) the hydrogels are collapsed due to complexation, however, at concentration of SDS solution equal to critical micelle concentration the gels contracted and then swollen again

  12. The radiation sensitivity of the haemopoietic microenvironment - effect of dose rate on ectopic ossicle formation

    International Nuclear Information System (INIS)

    The haemopoietic microenvironment (HM) consists of a complex mixture of cellular types and extra-cellular matrix. It is essential for prolonged haemopoiesis in both the normal situation and after bone marrow transplantation. The competence of the HM can be assessed by ectopic grafting of femoral marrow. A complete haemopoietic organ develops at the site of implantation. Stem cells (CFU-S) which inhabit the ossicle formed after ectopic implantation can be measured, to assess the function of the engrafted HM to support haemopoiesis. Using this functional endpoint the radiation sensitivity of the HM has been examined at both high and low dose rates, and it is concluded that high doses of γ-irradiation delivered at 4 Gy/min or 0.016 Gy/min have widely different effects on the HM, the former proving much more damaging than the latter. 16 refs.; 2 figs

  13. Radiation-sensitive mutant of hypertoxinogenic strain 569B of Vibro cholerae

    International Nuclear Information System (INIS)

    A radiation-sensitive mutant of the hypertoxinogenic strain 569B of Vibrio cholerae was isolated and characterized. The mutant, designated V. cholerae 569Bsub(s), lacks both excision- and medium-dependent dark-repair mechanisms of UV-induced DNA damage while retaining the wild-type photoreactivating capability. Analysis of the UV-irradiated cell DNA by velocity sedimentation in alkaline sucrose gradient suggests that UV-induced pyrimidine dimers may not be incised in these cells. In contrast to the wild-type cells, the mutant cell DNA was degraded after treatment with nalidixic acid. The mutant cells failed to produce any detectable amount of cholera toxin as measured by ileal-loop assay. (orig.)

  14. Application of generalized estimating equations to a study in vitro of radiation sensitivity

    International Nuclear Information System (INIS)

    We describes an application of the generalized estimating equation (GEE) method (Liang K-Y, Zeger SL: Longitudinal data analysis using generalized linear models. Biometrika 73:13-22, 1986) for regression analyses of correlated Poisson data. As an alternative to the use of an arbitrarily chosen working correlation matrix, we demonstrate the use of GEE with a reasonable model for the true covariance structure among repeated observations within individuals. We show that, under such a split-plot design with large clusters, the asymptotic relative efficiency of GEE with simple (independence or exchangeable) working correlation matrices is rather low. We also illustrate the use of GEE with an empirically estimated model for overdispersion in a large study of radiation sensitivity where cluster size is small and a simple working correlation structure is sufficient. We conclude by summarizing issues and needs for further work concerning efficiency of the GEE parameter estimates in practice. (author)

  15. Study of the sensitivity of the radiation transport problem in a scattering medium

    International Nuclear Information System (INIS)

    In this work, the system of differential equations obtained by the angular approach of the two-dimensional transport equation by the discrete ordinates method is solved through the formulation of finite elements with the objective of investigating the sensitivity of the outgoing flux of radiation with the incoming flux and the properties of absorption and scattering of the medium. The variational formulation for the system of differential equations of second order with the generalized boundary conditions of Neumann (third type) allows an easy implementation of the method of the finite elements with triangular mesh and approximation space of first order. The geometry chosen for the simulations is a circle with a non homogeneous circular form in its interior. The mapping of Dirichlet-Neumann is studied through various simulations involving the incoming flux, the outgoing flux and the properties of the medium. (author)

  16. Can climate sensitivity be estimated from short-term relationships of top-of-atmosphere net radiation and surface temperature?

    International Nuclear Information System (INIS)

    Increasing the knowledge in climate radiative feedbacks is critical for current climate studies. This work focuses on short-term relationships between global mean surface temperature and top-of-atmosphere (TOA) net radiation. The relationships may be used to characterize the climate feedback as suggested by some recent studies. As those recent studies, an energy balance model with ocean mixed layer and both radiative and non-radiative heat sources is used here. The significant improvement of current model is that climate system memories are considered. Based on model simulations, short-term relationship between global mean surface temperature and TOA net radiation (or the linear striation feature as suggested by previous studies) might represent climate feedbacks when the system had no memories. However, climate systems with the same short-term feedbacks but different memories would have a similar linear striation feature. This linear striation feature reflects only fast components of climate feedbacks and may not represent the total climate feedback even when the memory length of climate systems is minimal. The potential errors in the use of short-term relationships in estimations of climate sensitivity could be big. In short time scales, fast climate processes may overwhelm long-term climate feedbacks. Thus, the climate radiative feedback parameter obtained from short-term data may not provide a reliable estimate of climate sensitivity. This result also suggests that long-term observations of global surface temperature and TOA radiation are critical in the understanding of climate feedbacks and sensitivities.

  17. Evaluation of the radiation-sensitizer/protector and/or antioxidant efficiencies using Fricke and PAG dosimeters

    Science.gov (United States)

    Meesat, Ridthee; Jay-Gerin, Jean-Paul; Khalil, Abdelouahed; Lepage, Martin

    2009-05-01

    In this study, our aim is to assess the potential of Fricke and polyacrylamide gel (PAG) dosimeters to quantitatively evaluate the efficiency of potential radiation sensitizers/protectors and antioxidants. These compounds are of importance in radiotherapy as well as in disease prevention and promotion of health. The basic principle of the Fricke dosimeter is the radiation-induced oxidation of Fe2+ to Fe3+ in an aerated aqueous 0.4 M H2SO4. The production of ferric ions is most sensitive to the radical species produced in the radiolysis of water. Using this method, we observed that cystamine (one of the best of the known radioprotectors) can prevent oxydation of Fe2+ from reactive radiolysis species. However, one obvious disadvantage of the Fricke dosimeter is that it operates under highly acidic conditions (pH 0.46), which may degrade biological compounds. In contrast, the pH of the polyacrylamide gel (PAG) dosimeter is almost neutral, such that degradation of compounds is less probable. A change in R2-dose sensitivity was observed in the presence of radiosensitizers/radioprotectors and antioxidants. The protective effect of Trolox (a well-known antioxidant) and thiourea (a radioprotector) was readily observed using the PAG dosimeter. Incorporation of iodinated radiation sensitizers such as NaI and an iodine contrast agent led to a quantifiable sensitizer enhancement ratio. These studies suggest that the Fricke and the PAG dosimeters have the potential to evaluate the efficiency of radiation sensitizers/protectors and antioxidants.

  18. Radiation sensitivity of natural organic matter: Clay mineral association effects in the Callovo-Oxfordian argillite

    International Nuclear Information System (INIS)

    Clay-rich low-organic carbon formations (e.g., Callovo-Oxfordian argillite in France and Opalinus Clay in Switzerland) are considered as host rocks for radioactive waste disposal. The clay-organic carbon has a strong impact on the chemical stability of the clays. For this reason, the nature of the clay-organic carbon, the release of hydrophilic organic compounds, namely, humic (HA) and fulvic acids (FA) and the radiation sensitivity of the undisturbed host rock organics was investigated. The clay sample originates from Oxfordian argillite (447 m depth, borehole EST 104). HA and FA were extracted following the standard International Humic Substance Society (IHSS) isolation procedure. Synchrotron based (C-, K-, Ca-, O- and Fe-edge XANES) scanning transmission X-ray microscopy (STXM) and FT-IR microspectroscopy was used to identify under high spatial resolution the distribution of clay-organic matter with different functionality using principal component and cluster analysis. The results show that in this old (Jurassic) geological formation, small parts of the organic inventory (1-5%) keeps the structure/functionality and can be mobilized as hydrophilic humic substance type material (HA and FA). Target spectra analysis shows best correlation for isolated humic acids with organics found in smectite-rich regions, whereas the extractable FA has better spectral similarities with the illite mixed layer minerals (MLM) regions. After radiation of 1.7 GGy under helium atmosphere the same rock sample area was investigated for radiation damage. Radiation damage in the smectite and illite-MLM associated organic matter is comparably low with 20-30% total oxygen mass loss and 13-18% total carbon mass loss. A critical dose dc of 2.5 GGy and a optical density after infinite radiation (OD∝) of 54% was calculated under room temperature conditions. C(1s) XANES show a clear increase in C=C bonds especially in the illite-MLM associated organics. This results suggests a combination of

  19. Radiation sensitive indicator based on tetrabromophenol blue dyed poly(vinyl alcohol)

    International Nuclear Information System (INIS)

    Radiation sensitive indicators based on dyed polyvinyl alcohol (PVA) containing acid- sensitive dye (tetrabromophenol blue, TBPB) and chloral hydrate (CCl3·CH·(OH)2, 2,2,2-trichloroethane-1,1-diol) have been developed. These plastic film dosimeters undergo color change from blue (the alkaline form of TBPB) to yellow (the acidic form of TBPB), indicating acid formation. The concentration of radiation formed acids in the films containing different concentrations of chloral hydrate was calculated at different doses. These films can be used as dosimeters for food irradiation applications where the maximum of the useful dose ranges are between 1 and 8 kGy depending on chloral hydrate concentration in the film. The films have the advantage of negligible humidity effects on response in the intermediate range of relative humidity from 0 to 70% as good post irradiation stability when stored in the dark at room temperature. The overall combined uncertainty (at 2σ) associated with measurement of response (ΔA mm−1) at 623 nm for dose range 1–8 kGy is 4.53%. - Highlights: ► On irradiating TBPB/PVA films the color change from blue to green and yellow. ► The amount of acid formed depends on dose and concentration of chloral hydrate. ► The dose range 1–8 kGy the film can be used for food irradiation applications. ► The response of these films has negligible humidity effects from 0 to 70%. ► The combined uncertainty at 2σ using TBPB/PVA films was found to be 4.53%

  20. Oxygen at 2 atmospheres absolute pressure does not increase the radiation sensitivity of normal brain in rats

    International Nuclear Information System (INIS)

    Cranial radiation was administered to CD Fisher rats at 1.0, 1.5 and 2.0 atmospheres oxygen pressure. Life span following radiation was recorded. Surviving animals were killed at 28 weeks and the brains were examined independently by two neuropathologists. Survival time was significantly less in animals receiving higher doses of radiation but showed no relationship to the oxygen pressure in the environment of the animal at the time radiation was administered. Microscopic examination of the brain did not reveal any differences in animals radiated in a normobaric or hyperbaric oxygen environment. It is concluded that hyperbaric oxygen does not sensitize the normal brain to the effects of ionizing radiation

  1. 476 Severe Autoimmunity with Polyarticular Joint Disease Requiring Anti-TNF Therapy and T+B-NK+ Immunodeficiency in a Family with Small Stature and Intermediate Radiation Sensitivity

    OpenAIRE

    Torgerson, Troy; Ochs, Hans; Lu, Jun

    2012-01-01

    Background We have identified a family in which 3 of 4 children are affected with significant autoimmunity and immunodeficiency that does not fit any of the known disorders. We have embarked to characterize their defect and describe a completely new disorder. Methods Whole Exome Sequencing, T and B Cell Immunophenotyping, Radiation Sensitivity, Bacteriophage. Results The oldest affected child is female with severe polyarticular arthritis (treated with etanercept), eczema, diarrhea, short stat...

  2. Higher sensitivity of LEC strain rat in radiation-induced acute intestinal death

    International Nuclear Information System (INIS)

    LEC strain rats (LEC rats), which have been known to develop hereditarily spontaneous fulminant hepatitis 4-5 months after birth, were highly sensitive to whole-body X-irradiation as compared to WKAH strain rats (WKAH rats). Radiation-induced acute intestinal death occurred at doses higher than 6.5 Gy in LEC rats, and at doses higher than 12.8 Gy in WKAH rats, respectively. By the probit analysis of survival data, it was shown that the LD50/7 value of LEC rats was estimated to be 7.03 Gy which was significantly lower than that (12.99 Gy) of WKAH rats. Histopathological examinations of small intestines from LEC rats 2 days after irradiation at the dose of 8.5 Gy showed severe epithelial death together with edema, whereas little or no significant changes were noted in intestinal epithelium of 8.5 Gy-irradiated WKAH rats. These results suggest that the radiosensitivity of LEC rats to ionizing radiation appears to be higher than that of other strains of rats

  3. A system for determining the pharmacology of indirect radiation sensitizer drugs on multicellular spheroids

    International Nuclear Information System (INIS)

    We have characterized some of the physiology of multicellular spheroids of different sizes grown from Chinese hamster lung fibroblast (V79) cells. Among the parameters studied were oxygen tension distributions within the spheroid. This was achieved using ultramicroelectrodes with tip diameters of 1-5 mu and a perfusion system whereby environmental conditions such as flow, temperature, and chemical makeup of the milieu could be measured and controlled. Plateau pO/sup 2/ values of less than 10 mm Hg were consistently obtained from spheroids under various conditions. We were able to modify these distributions by use of indirect radiation sensitizer drugs such as mechlorethamine HCl (mustargen) at nontoxic doses. We have also made determinations of the inhibitory capacities of several other drugs on the respiration rate of constituent cells of multicellular spheroids in single-cell suspensions. We have concluded that there are indeed hypoxic cells in spheroids whose radioresistance may be modified by essentially nontoxic levels of indirect radiosensitizer drugs and that the system described shows great promise for screening agents which may modify radiation response

  4. Adipose Triglyceride Lipase (ATGL) and Hormone-Sensitive Lipase (HSL) Deficiencies Affect Expression of Lipolytic Activities in Mouse Adipose Tissues*

    OpenAIRE

    Morak, Maria; Schmidinger, Hannes; Riesenhuber, Gernot; Rechberger, Gerald N.; Kollroser, Manfred; Haemmerle, Guenter; Zechner, Rudolf; Kronenberg, Florian; Hermetter, Albin

    2012-01-01

    Adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) are key enzymes involved in intracellular degradation of triacylglycerols. It was the aim of this study to elucidate how the deficiency in one of these proteins affects the residual lipolytic proteome in adipose tissue. For this purpose, we compared the lipase patters of brown and white adipose tissue from ATGL (−/−) and HSL (−/−) mice using differential activity-based gel electrophoresis. This method is based on activity-r...

  5. Quality of medicinal plants traditionally used in Sudan as affected by ionizing radiation treatments

    International Nuclear Information System (INIS)

    This investigation was conducted to study the effect of gamma-radiation doses of 5, 10 and 15 KGy on the microbial and chemical quality as well as antioxidant activity of nine medical plants from 8 plant species grown in Sudan. The plant materials were collected from the country-side of Khartoum State as well as from local markets. Plant parts were selected according to their traditional uses as medicinal plants. Irradiation treatment was carried out or dried ground samples using doses of 5,10, 15 KGy from experimental cobalt-60 gamma source. Plants extracts were prepared using 80% methanol. The control and irradiated samples were analyzed for total bacterial count (cfu/g), secondary compounds, tannin content, total phenol, and antioxidant activity. Tannins, flavonoids, glycosides, anthraquinones, saponin and phenols were evaluated through major compounds in extracts. The total bacterial count indicated that the non- irradiated samples of Trigonella foenum-graecum L., Cassia senna (pods), Cassia senna (leaves), Acacia nilotica L., Brassica nigra L. Koch, Lepidium sativum L., Cymbopogon citratus and Hibiscus sabdariffa L. were highly contaminated with bacteria. The sample of Cymbopogon schoenanthus L. showed a lower count of bacteria (9x10'' 3 Cfu/g), which did not exceed the acceptable level. The samples irradiated with 5, 10 and 15 KGy of gamma radiation dose had significantly lower bacterial counts than the non-irradiated control. The highest sensitivity to gamma rays at 5 KGy dose was observed in Trigonella foenum-graecum L. and Acacia nilotica L. while the lowest sensitivity was in Cymbopogon schoenanthus L. At 15 KGy dose Hibiscus sabdariffa L. and Cymbopogon citratus showed complete absence of microorganisms. The highest reduction in tannin content (mg/L catechin) due to irradiation with 15 KGy dose was observed in Cymbopogon citratus, followed by Cymbopogon schoenanthus L., Cassia senna L. leaves Acacia nilotica L. and Hibiscus sabdariffa L.. Irradiation

  6. Bilateral implant reconstruction does not affect the quality of postmastectomy radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Alice Y., E-mail: hoa1234@mskcc.org [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Patel, Nisha [Drexel University College of Medicine, Philadelphia, PA (United States); Ohri, Nisha [Department of Radiation Oncology, Mount Sinai School of Medicine, New York, NY (United States); Morrow, Monica [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Mehrara, Babak J.; Disa, Joseph J.; Cordeiro, Peter G. [Department of Plastic Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Shi, Weiji; Zhang, Zhigang [Department of Biostatistics and Epidemiology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Gelblum, Daphna [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Nerbun, Claire T.; Woch, Katherine M.; Ballangrud, Ase [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); McCormick, Beryl; Powell, Simon N. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    2014-04-01

    To determine if the presence of bilateral implants, in addition to other anatomic and treatment-related variables, affects coverage of the target volume and dose to the heart and lung in patients receiving postmastectomy radiation therapy (PMRT). A total of 197 consecutive women with breast cancer underwent mastectomy and immediate tissue expander (TE) placement, with or without exchange for a permanent implant (PI) before radiation therapy at our center. PMRT was delivered with 2 tangential beams + supraclavicular lymph node field (50 Gy). Patients were grouped by implant number: 51% unilateral (100) and 49% bilateral (97). The planning target volume (PTV) (defined as implant + chest wall + nodes), heart, and ipsilateral lung were contoured and the following parameters were abstracted from dose-volume histogram (DVH) data: PTV D{sub 95%} > 98%, Lung V{sub 20}Gy > 30%, and Heart V{sub 25}Gy > 5%. Univariate (UVA) and multivariate analyses (MVA) were performed to determine the association of variables with these parameters. The 2 groups were well balanced for implant type and volume, internal mammary node (IMN) treatment, and laterality. In the entire cohort, 90% had PTV D{sub 95%} > 98%, indicating excellent coverage of the chest wall. Of the patients, 27% had high lung doses (V{sub 20}Gy > 30%) and 16% had high heart doses (V{sub 25}Gy > 5%). No significant factors were associated with suboptimal PTV coverage. On MVA, IMN treatment was found to be highly associated with high lung and heart doses (both p < 0.0001), but implant number was not (p = 0.54). In patients with bilateral implants, IMN treatment was the only predictor of dose to the contralateral implant (p = 0.001). In conclusion, bilateral implants do not compromise coverage of the target volume or increase lung and heart dose in patients receiving PMRT. The most important predictor of high lung and heart doses in patients with implant-based reconstruction, whether unilateral or bilateral, is treatment of

  7. A robust hypothesis test for the sensitive detection of constant speed radiation moving sources

    Energy Technology Data Exchange (ETDEWEB)

    Dumazert, Jonathan, E-mail: jonathan.dumazert@cea.fr [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Moline, Yoann; Sannié, Guillaume; Gameiro, Jordan; Normand, Stéphane [CEA, LIST, Laboratoire Capteurs Architectures Electroniques, 91191 Gif-sur-Yvette (France); Méchin, Laurence [CNRS, UCBN, Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen, 14050 Caen (France)

    2015-09-21

    Radiation Portal Monitors are deployed in linear networks to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal-to-noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive backgrounds, and a vehicle source carrier under the same respectively high and low count rate radioactive backgrounds, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm. It also guarantees that the optimal coverage factor for this compromise remains stable regardless of signal-to-noise ratio variations between 2 and 0.8, therefore allowing the final user to parametrize the test with the sole prior knowledge of background amplitude.

  8. A robust hypothesis test for the sensitive detection of constant speed radiation moving sources

    International Nuclear Information System (INIS)

    Radiation Portal Monitors are deployed in linear networks to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal-to-noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive backgrounds, and a vehicle source carrier under the same respectively high and low count rate radioactive backgrounds, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm. It also guarantees that the optimal coverage factor for this compromise remains stable regardless of signal-to-noise ratio variations between 2 and 0.8, therefore allowing the final user to parametrize the test with the sole prior knowledge of background amplitude

  9. A robust hypothesis test for the sensitive detection of constant speed radiation moving sources

    Science.gov (United States)

    Dumazert, Jonathan; Coulon, Romain; Kondrasovs, Vladimir; Boudergui, Karim; Moline, Yoann; Sannié, Guillaume; Gameiro, Jordan; Normand, Stéphane; Méchin, Laurence

    2015-09-01

    Radiation Portal Monitors are deployed in linear networks to detect radiological material in motion. As a complement to single and multichannel detection algorithms, inefficient under too low signal-to-noise ratios, temporal correlation algorithms have been introduced. Test hypothesis methods based on empirically estimated mean and variance of the signals delivered by the different channels have shown significant gain in terms of a tradeoff between detection sensitivity and false alarm probability. This paper discloses the concept of a new hypothesis test for temporal correlation detection methods, taking advantage of the Poisson nature of the registered counting signals, and establishes a benchmark between this test and its empirical counterpart. The simulation study validates that in the four relevant configurations of a pedestrian source carrier under respectively high and low count rate radioactive backgrounds, and a vehicle source carrier under the same respectively high and low count rate radioactive backgrounds, the newly introduced hypothesis test ensures a significantly improved compromise between sensitivity and false alarm. It also guarantees that the optimal coverage factor for this compromise remains stable regardless of signal-to-noise ratio variations between 2 and 0.8, therefore allowing the final user to parametrize the test with the sole prior knowledge of background amplitude.

  10. Radiation sensitivity of bacteria and virus in porcine xenoskin for dressing agent

    Science.gov (United States)

    Jo, Eu-Ri; Jung, Pil-Mun; Choi, Jong-il; Lee, Ju-Woon

    2012-08-01

    In this study, gamma irradiation sensitivities of bacteria and viruses in porcine skin were evaluated to establish the optimum sterilization condition for the dressing material and a xenoskin graft. Escherichia coli and Bacillus subtilis were used as model pathogens and inoculated at 106-107 log CFU/g. As model viruses, porcine parvovirus (PPV), bovine viral diarrhea virus (BVDV), and poliovirus were used and inoculated at 105-106 TCID50/g into porcine skin. The D10 value of E. coli was found to be 0.25±0.1 kGy. B. subtilis endospores produced under stressful environmental conditions showed lower radiation sensitivity as D10 was 3.88±0.3 kGy in porcine skin. The D10 values of PPV, BVDV, and poliovirus were found to be 1.73±0.2, 3.81±0.2, and 6.88±0.3 kGy, respectively. These results can offer the basic information required for inactivating pathogens by gamma irradiation and achieving dressing material and porcine skin grafts.

  11. Radiation sensitivity of bacteria and virus in porcine xenoskin for dressing agent

    International Nuclear Information System (INIS)

    In this study, gamma irradiation sensitivities of bacteria and viruses in porcine skin were evaluated to establish the optimum sterilization condition for the dressing material and a xenoskin graft. Escherichia coli and Bacillus subtilis were used as model pathogens and inoculated at 106–107 log CFU/g. As model viruses, porcine parvovirus (PPV), bovine viral diarrhea virus (BVDV), and poliovirus were used and inoculated at 105–106 TCID50/g into porcine skin. The D10 value of E. coli was found to be 0.25±0.1 kGy. B. subtilis endospores produced under stressful environmental conditions showed lower radiation sensitivity as D10 was 3.88±0.3 kGy in porcine skin. The D10 values of PPV, BVDV, and poliovirus were found to be 1.73±0.2, 3.81±0.2, and 6.88±0.3 kGy, respectively. These results can offer the basic information required for inactivating pathogens by gamma irradiation and achieving dressing material and porcine skin grafts.

  12. Parameter sensitivities affecting the flutter speed of a MW-sized blade.

    Energy Technology Data Exchange (ETDEWEB)

    Lobitz, Donald Wayne, Jr.

    2005-08-01

    With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5-9 m), both modern and early designs, the flutter speeds are in the range of 3.5-6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.

  13. Parameter sensitivities affecting the flutter speed of a MW-sized blade.

    Energy Technology Data Exchange (ETDEWEB)

    Lobitz, Donald Wayne, Jr.

    2004-10-01

    With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5-9 m), both modern and early designs, the flutter speeds are in the range of 3.5-6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.

  14. Sensitivity Analysis on Fu-Liou-Gu Radiative Transfer Model for different lidar aerosol and cloud profiles

    Science.gov (United States)

    Lolli, Simone; Madonna, Fabio; Rosoldi, Marco; Pappalardo, Gelsomina; Welton, Ellsworth J.

    2016-04-01

    The aerosol and cloud impact on climate change is evaluated in terms of enhancement or reduction of the radiative energy, or heat, available in the atmosphere and at the Earth's surface, from the surface (SFC) to the Top Of the Atmosphere (TOA) covering a spectral range from the UV (extraterrestrial shortwave solar radiation) to the far-IR (outgoing terrestrial longwave radiation). Systematic Lidar network measurements from permanent observational sites across the globe are available from the beginning of this current millennium. From the retrieved lidar atmospheric extinction profiles, inputted in the Fu-Liou-Gu (FLG) Radiative Transfer code, it is possible to evaluate the net radiative effect and heating rate of the different aerosol species and clouds. Nevertheless, the lidar instruments may use different techniques (elastic lidar, Raman lidar, multi-wavelength lidar, etc) that translate into uncertainty of the lidar extinction retrieval. The goal of this study is to assess, applying a MonteCarlo technique and the FLG Radiative Transfer model, the sensitivity in calculating the net radiative effect and heating rate of aerosols and clouds for the different lidar techniques, using both synthetic and real lidar data. This sensitivity study is the first step to implement an automatic algorithm to retrieve the net radiative forcing effect of aerosols and clouds from the long records of aerosol measurements available in the frame of EARLINET and MPLNET lidar networks.

  15. An olfactory-limbic model of multiple chemical sensitivity syndrome: Possible relationships to kindling and affective spectrum disorders

    Energy Technology Data Exchange (ETDEWEB)

    Bell, I.R.; Miller, C.S.; Schwartz, G.E. (Univ. of Arizona Health Sciences Center, Tucson (United States))

    1992-08-01

    This paper reviews the clinical and experimental literature on patients with multiple adverse responses to chemicals (Multiple Chemical Sensitivity Syndrome-MCS) and develops a model for MCS based on olfactory-limbic system dysfunction that overlaps in part with Post's kindling model for affective disorders. MCS encompasses a broad range of chronic polysymptomatic conditions and complaints whose triggers are reported to include low levels of common indoor and outdoor environmental chemicals, such as pesticides and solvents. Other investigators have found evidence of increased prevalence of depression, anxiety, and somatization disorders in MCS patients and have concluded that their psychiatric conditions account for the clinical picture. However, none of these studies has presented any data on the effects of chemicals on symptoms or on objective measures of nervous system function. Synthesis of the MCS literature with large bodies of research in neurotoxicology, occupational medicine, and biological psychiatry, suggests that the phenomenology of MCS patients overlaps that of affective spectrum disorders and that both involve dysfunction of the limbic pathways. Animal studies demonstrate that intermittent repeated low level environmental chemical exposures, including pesticides, cause limbic kindling. Kindling (full or partial) is one central nervous system mechanism that could amplify reactivity to low levels of inhaled and ingested chemicals and initiate persistent affective, cognitive, and somatic symptomatology in both occupational and nonoccupational settings. As in animal studies, inescapable and novel stressors could cross-sensitize with chemical exposures in some individuals to generate adverse responses on a neurochemical basis. The olfactory-limbic model raises testable neurobiological hypotheses that could increase understanding of the multifactorial etiology of MCS and of certain overlapping affective spectrum disorders. 170 refs.

  16. Multidisciplinary approach to assess the sensitivity of dwarf tomato plants to low-LET ionising radiation

    Science.gov (United States)

    De Micco, Veronica; De Pascale, Stefania; Aronne, Giovanna; Paradiso, Roberta; Vitaglione, Paola; Turano, Mimmo; Arena, Carmen

    Ionising radiation, acting alone or in interaction with microgravity and other environmental constraints, may affect plant at molecular, morpho-structural and physiological level. The intensity of the plant’s response depends on the properties of radiation and on the features of the plant itself. Indeed, different species are characterised by different susceptibility to radiation which may change during the life course. The aim of this research was to study the radiosensitivity to low-LET ionising radiation of plants of dwarf tomato (Solanum lycopersicum L. ‘Microtom’) at two phenological phases (vegetative and reproductive), within the purpose of analysing plants for consideration as candidates for Bioregenerative Life Support Systems (BLSS) in Space. To pursue this objective, plants of the cultivar Microtom were irradiated with different doses of X-rays either at the stage of the second true leaf (VP - vegetative phase) or when at least one flower was blossomed (RP - reproductive phase). Plant’s response to ionising radiation was assessed through a multidisciplinary approach combining genetic analyses, ecophysiological measurements, morpho-anatomical characterisation of leaves and fruits, nutritional analyses of fruits. Growth, molecular and morpho-functional traits were measured during plant development up to fruiting in both VP and RP plant groups, and compared with non-irradiated control plants. Plant growth was monitored weekly recording parameters such as plant height, number of leaves, leaf area, flowering and fruiting rate. Potential DNA alterations were explored through Random Amplified Polymorphic DNA (RAPD) technique. The efficiency of the photosynthetic apparatus was evaluated by determining photosynthetic pigment composition, photochemistry and leaf gas exchanges. Leaf and fruit structure were analysed through light and epi-fluorescence microscopy. Leaf anatomical traits related to photosynthetic efficiency, and to structural radioprotection

  17. A position-sensitive scintillation detector for two-dimensional angular correlation of annihilation radiation using metal-package position-sensitive photomultiplier tubes

    International Nuclear Information System (INIS)

    We have constructed and tested a prototype of a new position sensitive γ-ray detector which consists of an array of 2.6x2.6x18 mm3 BGO scintillator blocks, a light guide, and four metal-package position-sensitive photomultiplier tubes (R5900-00-C8) recently developed by Hamamatsu Photonics Co. Ltd. Scalability of the detector of this type makes it possible to construct a larger detector using many PS-PMTs, which will be useful for the two-dimensional angular correlation of annihilation radiation apparatus

  18. A position-sensitive scintillation detector for two-dimensional angular correlation of annihilation radiation using metal-package position-sensitive photomultiplier tubes

    CERN Document Server

    Inoue, K; Saito, H; Nagashima, Y; Hyodo, T; Muramatsu, S; Nagai, S

    1999-01-01

    We have constructed and tested a prototype of a new position sensitive gamma-ray detector which consists of an array of 2.6x2.6x18 mm sup 3 BGO scintillator blocks, a light guide, and four metal-package position-sensitive photomultiplier tubes (R5900-00-C8) recently developed by Hamamatsu Photonics Co. Ltd. Scalability of the detector of this type makes it possible to construct a larger detector using many PS-PMTs, which will be useful for the two-dimensional angular correlation of annihilation radiation apparatus.

  19. Radiation Induced-Grafting of Sensitive Binary Monomers onto Polypropylene Films by γ-Rays

    International Nuclear Information System (INIS)

    Binary graft copolymerization of pH sensitive acrylic acid (AAc) and thermosensitive N-isopropylacrylamide (NIPAAm) monomers onto polypropylene films (PP), was carried out by two steps method, and their pH and thermal sensitivity were studied. Graft polymerization of AAc onto PP was carried out by a pre-irradiation oxidative method using a 60Co gamma radiation source (Gamma Beam 651 PT, Nordion International Inc.) with activity of 25,000 Curies. The influence of synthesis conditions, such as pre-irradiation dose, reaction time, monomer concentration, and reaction temperature was studied. Grafting of PP films of 1 x 5 cm size was carried out in glass ampoules, pre-irradiated films in air, were placed in ampoules containing monomer (AAc) in water (40/60 % vol.). Argon was purged into the ampoule to remove air trapped inside the reaction mixture and the ampoule was subsequently placed at the constant temperature of 50 degree at different reaction time; then the PP films were extracted with water to remove any homopolymer formed in the reaction. The samples were dried under vacuum and the graft percentage was determined. Grafting of NIPAAm onto PP-g-AAc was carried out with the same procedure. Low Critical Solution Temperature (LCST) of the films was measured by water absorption and water contact angle, and the thermosensitivity of the samples, defined as the ratio of the grafted samples swelling percentage at room temperature and 35 degree, and pH sensitivity defined as the ratio of the grafted samples swelling percentage at pH 2 and 8, were calculated. Binary grafting was confirmed by Infrared (FTIR-ATR)

  20. Behavioural responses to thermal conditions affect seasonal mass change in a heat-sensitive northern ungulate.

    Directory of Open Access Journals (Sweden)

    Floris M van Beest

    Full Text Available BACKGROUND: Empirical tests that link temperature-mediated changes in behaviour (activity and resource selection to individual fitness or condition are currently lacking for endotherms yet may be critical to understanding the effect of climate change on population dynamics. Moose (Alces alces are thought to suffer from heat stress in all seasons so provide a good biological model to test whether exposure to non-optimal ambient temperatures influence seasonal changes in body mass. Seasonal mass change is an important fitness correlate of large herbivores and affects reproductive success of female moose. METHODOLOGY/PRINCIPAL FINDINGS: Using GPS-collared adult female moose from two populations in southern Norway we quantified individual differences in seasonal activity budget and resource selection patterns as a function of seasonal temperatures thought to induce heat stress in moose. Individual body mass was recorded in early and late winter, and autumn to calculate seasonal mass changes (n = 52 over winter, n = 47 over summer. We found large individual differences in temperature-dependent resource selection patterns as well as within and between season variability in thermoregulatory strategies. As expected, individuals using an optimal strategy, selecting young successional forest (foraging habitat at low ambient temperatures and mature coniferous forest (thermal shelter during thermally stressful conditions, lost less mass in winter and gained more mass in summer. CONCLUSIONS/SIGNIFICANCE: This study provides evidence that behavioural responses to temperature have important consequences for seasonal mass change in moose living in the south of their distribution in Norway, and may be a contributing factor to recently observed declines in moose demographic performance. Although the mechanisms that underlie the observed temperature mediated habitat-fitness relationship remain to be tested, physiological state and individual variation in

  1. Calibration of non-discriminating scintillating instruments for sensitivities to naturally occuring gamma radiation emitting radionuclides at environmental concentrations

    International Nuclear Information System (INIS)

    A method of calibrating non-discriminating gamma radiation detectors for environmental level measurements is described. It is based on a method used to calibrate field gamma spectrometers, and has several advantages over the more traditional point-source approach. Radiological measurements are taken on pads with known concentrations of potassium, uranium and thorium, and the sensitivities to these naturally occurring terrestrial sources of gamma radiation are determined. Measurements can then be converted into radionuclide concentration or exposure rates. (author)

  2. Investigation of some parameters influencing the sensitivity of human tooth enamel to gamma radiation using electron paramagnetic resonance

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance (EPR) has been successfully used as a physical technique for gamma radiation dose reconstruction using calcified tissues. To minimize potential discrepancies between EPR readings in future studies, the effects of cavity response factor, tooth position and donor gender on the estimated gamma radiation dose were studied. It was found that the EPR response per sample mass used for assessment of doses in teeth outside of the 70-100 mg range should be corrected by a factor which is a function of the sample mass. In the EPR measurements, the difference in sensitivity of different tooth positions to γ-radiation was taken into consideration. It was determined that among all the premolars and molars tooth positions, the relative standard deviation of sensitivity was 6.5%, with the wisdom teeth and the first molars having the highest and lowest sensitivity to γ-radiation, respectively. The current results reveal no effect of the donor gender on the sensitivity to γ-radiation. (author)

  3. Assessment of the radiation sensitivity of patients after conditioning irradiation as preparation for bone marrow or stem cell transplantation

    International Nuclear Information System (INIS)

    The knowledge on the radiation sensitivity of individual patients would allow a better planning of conditioning irradiation including the possibility of dose increase that might enhance the chance of a successful bone marrow or stem cell transplantation. The study was focused on the search of reliable and fast laboratory test procedures to predict the individual radiation sensitivity. Several blood tests were evaluated with respect to their appropriateness: mostly flow-cytometric test on lymphocytes: micronuclei, cell proliferation, apoptosis activation of cytokines and the total number of leucocytes, blood stem cells CD4+ and CD8+ lymphocytes, and a spectro-photometric test of blood plasma for the determination of the antioxidative capacity

  4. Study of the effects of sensitizer, radiation dose and leaching on the properties of irradiated field latex

    International Nuclear Information System (INIS)

    The effects of sensitizer, radiation dose and leaching on the properties of irradiated natural rubber field latex have been studied. Carbon tetrachloride, carbon tetrachloride + n-butyl acrylate and n-butyl acrylate + hydrogen peroxide were used as sensitizer for radiation chemical reaction. Samples were irradiated at the dose rate of 13-14 kGy/hr with 1480 TBq 60Co gamma source at room temperature. The samples were leached at various leaching conditions. Tensile strength, gel fraction, permanent set, swelling ratio, crosslinking density etc were measured by standard methods. (author). 18 refs., 8 tabs

  5. Radiation and nuclear risk - considerations for those affected. A RISKPERCOM summary report

    International Nuclear Information System (INIS)

    This report contains four summaries of national case reports from France, Norway, Spain and Sweden, published elsewhere, and a general discussion. The case reports deal with various aspects of radioactive waste and radioactive fallout, and the situation and information needs of affected populations. The four case studies have not examined the same problems. Nevertheless, they are focusing segments of the population experiencing or perceiving an actual or future radiation or nuclear risk larger than the average citizen. The studies show problems in addressing those groups, and with different solution in the four countries. No definite answer can be given as to which approach is the most rewarding. A multitude of factors may contribute to any success. It seems, however, that an increased emphasis on communication and public involvement versus information alone is considered important. The situations reported cannot be said to have achieved effective public involvement. Indeed, in the siting cases, it may be hypothesized that the contradiction between stated intention to involve the public, and the actual opportunities for (unorganized) residents to make themselves heard, may contribute to tension and detract from credibility. Still, the trends observed in these case studies toward more consideration by authorities of communication needs, should be welcomed

  6. Radiation and nuclear risk - considerations for those affected. A RISKPERCOM summary report

    Energy Technology Data Exchange (ETDEWEB)

    Reitan, J.B.; Mays, C.; Lindstroem, A.L.C.; Sjoeberg, L.; Toennessen, A

    1999-07-01

    This report contains four summaries of national case reports from France, Norway, Spain and Sweden, published elsewhere, and a general discussion. The case reports deal with various aspects of radioactive waste and radioactive fallout, and the situation and information needs of affected populations. The four case studies have not examined the same problems. Nevertheless, they are focusing segments of the population experiencing or perceiving an actual or future radiation or nuclear risk larger than the average citizen. The studies show problems in addressing those groups, and with different solution in the four countries. No definite answer can be given as to which approach is the most rewarding. A multitude of factors may contribute to any success. It seems, however, that an increased emphasis on communication and public involvement versus information alone is considered important. The situations reported cannot be said to have achieved effective public involvement. Indeed, in the siting cases, it may be hypothesized that the contradiction between stated intention to involve the public, and the actual opportunities for (unorganized) residents to make themselves heard, may contribute to tension and detract from credibility. Still, the trends observed in these case studies toward more consideration by authorities of communication needs, should be welcomed.

  7. Pomegranate Supplementation Improves Affective and Motor Behavior in Mice after Radiation Exposure

    OpenAIRE

    Dulcich, Melissa S.; Hartman, Richard E.

    2013-01-01

    Currently, NASA has plans for extended space travel, and previous research indicates that space radiation can have negative effects on cognitive skills as well as physical and mental health. With long-term space travel, astronauts will be exposed to greater radiation levels. Research shows that an antioxidant-enriched diet may offer some protection against the cellular effects of radiation and may provide significant neuroprotection from the effects of radiation-induced cognitive and behavior...

  8. Rural areas affected by the Chernobyl accident: radiation exposure and remediation strategies.

    Science.gov (United States)

    Jacob, P; Fesenko, S; Bogdevitch, I; Kashparov, V; Sanzharova, N; Grebenshikova, N; Isamov, N; Lazarev, N; Panov, A; Ulanovsky, A; Zhuchenko, Y; Zhurba, M

    2009-12-15

    Main objectives of the present work were to develop an internationally agreed methodology for deriving optimized remediation strategies in rural areas that are still affected by the Chernobyl accident, and to give an overview of the radiological situation in the three affected countries, Belarus, Russia and Ukraine. Study settlements were defined by having in 2004 less than 10,000 inhabitants and official dose estimates exceeding 1 mSv. Data on population, current farming practices, contamination of soils and foodstuffs, and remedial actions previously applied were collected for each of such 541 study settlements. Calculations of the annual effective dose from internal radiation were validated with extensive data sets on whole body counter measurements. According to our calculations for 2004, in 290 of the study settlements the effective dose exceeded 1 mSv, and the collective dose in these settlements amounted to about 66 person-Sv. Six remedial actions were considered: radical improvement of grassland, application of ferrocyn to cows, feeding pigs with uncontaminated fodder before slaughter, application of mineral fertilizers for potato fields, information campaign on contaminated forest produce, and replacement of contaminated soil in populated areas by uncontaminated soil. Side effects of the remedial actions were quantified by a 'degree of acceptability'. Results are presented for two remediation strategies, namely, Strategy 1, in which the degree of acceptability was given a priority, and Remediation Strategy 2, in which remedial actions were chosen according to lowest costs per averted dose only. Results are highly country-specific varying from preference for soil replacement in populated areas in Belarus to preference for application of ferrocyn to cows in Ukraine. Remedial actions in 2010 can avert a large collective dose of about 150 person-Sv (including averted doses, which would be received in the following years). Nevertheless, the number of

  9. Lactose in milk replacer can partly be replaced by glucose, fructose, or glycerol without affecting insulin sensitivity in veal calves.

    Science.gov (United States)

    Pantophlet, A J; Gilbert, M S; van den Borne, J J G C; Gerrits, W J J; Roelofsen, H; Priebe, M G; Vonk, R J

    2016-04-01

    Calf milk replacer (MR) contains 40 to 50% lactose. Lactose strongly fluctuates in price and alternatives are desired. Also, problems with glucose homeostasis and insulin sensitivity (i.e., high incidence of hyperglycemia and hyperinsulinemia) have been described for heavy veal calves (body weight >100kg). Replacement of lactose by other dietary substrates can be economically attractive, and may also positively (or negatively) affect the risk of developing problems with glucose metabolism. An experiment was designed to study the effects of replacing one third of the dietary lactose by glucose, fructose, or glycerol on glucose homeostasis and insulin sensitivity in veal calves. Forty male Holstein-Friesian (body weight=114±2.4kg; age=97±1.4 d) calves were fed an MR containing 462g of lactose/kg (CON), or an MR in which 150g of lactose/kg of MR was replaced by glucose (GLU), fructose (FRU), or glycerol (GLY). During the first 10d of the trial, all calves received CON. The CON group remained on this diet and the other groups received their experimental diets for a period of 8 wk. Measurements were conducted during the first (baseline) and last week of the trial. A frequently sampled intravenous glucose tolerance test was performed to assess insulin sensitivity and 24 h of urine was collected to measure glucose excretion. During the last week of the trial, a bolus of 1.5g of [U-(13)C] substrates was added to their respective meals and plasma glucose, insulin, and (13)C-glucose responses were measured. Insulin sensitivity was low at the start of the trial and remained low [1.2±0.1 and 1.0±0.1 (mU/L)(-1) × min(-1)], and no treatment effect was noted. Glucose excretion was low at the start of the trial (3.4±1.0g/d), but increased in CON and GLU calves (26.9±3.9 and 43.0±10.6g/d) but not in FRU and GLY calves. Postprandial glucose was higher in GLU, lower in FRU, and similar in GLY compared with CON calves. Postprandial insulin was lower in FRU and GLY and similar

  10. Sensitivities to monochromatic 254-nm and 365-nm radiation of closely related strains of Saccharomyces cerevisiae with differing repair capabilities

    International Nuclear Information System (INIS)

    Sensitivity to monochromatic 254- and 365-nm radiation was compared in closely related yeast strains with defects in one or more of the excision-repair (rad1), error-prone repair (rad18), or recombinational-repair (rad51) pathways. At 254 nm, mutants defective in a single repair pathway exhibited slight to moderate UV sensitivity;,those defective in two separate pathways were somewhat more UV sensitive, while triple mutants defective in all three pathways exhibited extreme UV sensitivity with a lethal event corresponding to 0.05 J m-2. Repair defects also rendered mutants sensitive to 365-nm radiation: strains with single defects exhibited slight sensitivity, mutants with two defective pathways were more sensitive, and triple mutants exhibited maximal sensitivity with a lethal event corresponding to 2.4 x 104 J m-2. Evidence for dimer involvement in the yeast mutant was obtained by demonstrating that lethality at both 254 and 365 nm was photoreactivated by light at 405 nm. (author)

  11. Sensitivity analysis of performance of crop growth simulation models to daily solar radiation estimation methods in Iran

    Energy Technology Data Exchange (ETDEWEB)

    Farhadi Bansouleh, B. [International Institute for Geo-Information Science and Earth Observation (ITC), P.O. Box 6, 7500 AA Enschede (Netherlands); Water Engineering Department, Faculty of Agriculture, Razi University, Kermanshah (Iran); Sharifi, M.A. [International Institute for Geo-Information Science and Earth Observation (ITC), P.O. Box 6, 7500 AA Enschede (Netherlands); Van Keulen, H. [Plant Production Systems Group, Wageningen University, P.O. Box 430, 6700 AK Wageningen (Netherlands); Plant Research International, Wageningen University and Research Centre, P.O. Box 16, 6700 AA Wageningen (Netherlands)

    2009-11-15

    Solar radiation is the single most important environmental factor driving canopy photosynthesis and transpiration. This weather characteristic is measured only in a limited number of weather stations. Hence, in many situations it has to be estimated from other weather characteristics such as sunshine duration and temperature using empirical relations. In this study, the Aangstrom and Hargreaves formulas have been used for solar radiation estimation, based on monthly and annual weather data for three weather stations in Esfahan province, Iran. Deviations of estimated solar radiation from measured values (both absolute and relative) varied with month of the year and with estimation method. Estimated and measured radiation values were used in a crop growth simulation model to explore sensitivity of simulated production with respect to radiation estimation method. Maximum deviation for winter barley and silage maize was around 9%. (author)

  12. Investigation of the modifying effects of vitamin A and hypoxic cell sensitizers in radiation carcinogenesis in mice

    International Nuclear Information System (INIS)

    The effect of vitamin A (retinyl acetate) and three hypoxic cell sensitizers (metronidazole, misonidazole and desmethylmisonidazole) on lung tumor development in strain A mice exposed to radiation was assessed. In experiments involving vitamin A, two groups of mice were fed a low vitamin A diet (< 100 IU/100g diet) while the two other groups were fed a high vitamin A diet (800 IU/100 g diet). After two weeks one group maintained on the high vitamin A diet and one group maintained on the low vitamin A diet were given an acute dose of 500 rad of gamma radiation to the thoracic region. Mice were killed, their lungs were removed and the number of surface adenomas were counted. There was a significant increase in the number of mice bearing lung tumors and the mean number of lung tumors per mouse in the irradiated group maintained on the high vitamin A diet at 40 weeks post irradiation as compared to the irradiated group maintained on a low vitamin A diet. In the other experiment two dose levels of the hypoxic cell sensitizers, 0.2 mg/g and 0.6 mg/g, were used either alone or in combination with 900 rad of gamma radiation in a fractionated dose schedule of twice a week for three weeks. In the groups of mice which received hypoxic cell sensitizers only, the prevalence and the mean number of lung tumors per mouse were somewhat increased in the higher dose group (0.6 mg/g) of misonidazole but was not significantly different from the control animals in the other two sensitizer groups. The combination of hypoxic cell sensitizer and radiation did not show any significant enhancement of lung tumor response when compared with the group which received radiation only. The dose of radiation used in this study significantly enhanced lung tumor formation in mice when compared with the control group

  13. Solar Load Inputs for USARIEM Thermal Strain Models and the Solar Radiation-Sensitive Components of the WBGT Index

    Science.gov (United States)

    Matthew, William T.; Santee, William R.; Berglund, Larry G.

    2001-06-01

    This report describes processes we have implemented to use global pyranometer-based estimates of mean radiant temperature as the common solar load input for the Scenario model, the USARIEM heat strain model, and for the computation of the solar radiation sensitive components of the Wet Bulb Globe Temperature (WBGT) index.

  14. After-Ripening of Red Pepper (Capsicum Annuum) as Affected by Ionizing Radiation

    International Nuclear Information System (INIS)

    The direct effect of X-rays on freshly picked, sweet red pepper at dose levels of between 0 and 800 krad, and on the after-ripening of red pepper at dose levels of between 0 and 100 krad, was investigated. As an effect of the irradiation of between 400 and 800 krad, the pericarps softened; the carotenoid content, however, was not substantially reduced, even at a dose of 800 krad. During the nine weeks' storage period at room temperature, subsequent to irradiation, an increase of about 90% of the total pigment content, expressed as capsanthin, was observed in the samples not treated. The formation of the carotenoid pigments was accelerated, to some extent, by 80 rad, and substantially accelerated by treatment of 2 krad. The samples treated at the 2-krad level reached the same pigment content in three weeks as the control samples in eight weeks. In the radiation-treated samples, however, the pigment content decreased after the fourth to fifth week of storage. Dose levels above 10 krad slowed down or inhibited the formation of carotenoids during storage (after ripening). The reducing sugar content and the rate of drying were not affected by 0 to 100-krad doses. Since the several hundred kilorad irradiation doses needed to destroy, or substantially inhibit, the growth of moulds causing the deterioration of red pepper of high moisture content have a deleterious effect, the application of irradiation to decrease storage losses in fresh, picked red pepper does not seem to be advisable. The application, however, of the very low doses stimulating carotenoid formation does seem to be promising in view of shortening the after-ripening period and increasing the pigment content. Further investigations are needed to establish the most suitable storage conditions for the after-ripening of red peppers and the causes responsible for decrease in the carotenoid content of irradiated fruits in the second half of the storage period. (author)

  15. C/EBPδ Deficiency Sensitizes Mice to Ionizing Radiation-Induced Hematopoietic and Intestinal Injury

    OpenAIRE

    Pawar, Snehalata A.; Shao, Lijian; Chang, Jianhui; Wang, Wenze; Pathak, Rupak; Zhu, Xiaoyan; Wang, Junru; Hendrickson, Howard; Boerma, Marjan; Sterneck, Esta; Zhou, Daohong; Hauer-Jensen, Martin

    2014-01-01

    Knowledge of the mechanisms involved in the radiation response is critical for developing interventions to mitigate radiation-induced injury to normal tissues. Exposure to radiation leads to increased oxidative stress, DNA-damage, genomic instability and inflammation. The transcription factor CCAAT/enhancer binding protein delta (Cebpd; C/EBPδ is implicated in regulation of these same processes, but its role in radiation response is not known. We investigated the role of C/EBPδ in radiation-i...

  16. Effects of thermal sensitization on radiation-induced segregation in type 304 stainless steel irradiated with He-ions

    International Nuclear Information System (INIS)

    Type 304 stainless steels, solution-annealed and thermally sensitized at 923 K for 0.5 to 24 h, were He-ion-irradiated up to about 4 dpa at 723 K and radiation-induced segregation (RIS) at grain boundaries was measured by EDS analysis using a FEG-TEM. Ni, Si and P were enriched, and Cr was depleted at the grain boundaries by irradiation. However, although the irradiation dose was the same for the specimens, the RIS of the elements linearly increased with the logarithm of the thermally sensitizing time, except for Cr in the specimen thermally sensitized for 24 h. The enhancement of RIS was attributed to the radiation-induced point defects having large mobility in thermally sensitized stainless steels, because of an expected decrease in C near the grain boundaries and in the matrix after the sensitization heat treatments. It was clarified by the electrochemical potentiokinetic reactivation test (EPR) that the degree of sensitization increased with the progress of Cr depletion at grain boundaries. The Cr concentration at grain boundaries in the heavily sensitized specimen was not changed, and the width of the depleted area was slightly narrowed by the irradiation. This result could be explained that the diffusion of Cr due to initial Cr concentration gradient near grain boundaries exceeded the inverse Kirkendall effect. (orig.)

  17. Comparative radiation impact on biota and man in the area affected by the accident at the Chernobyl nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Fesenko, S.V. [Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, Kaluga region, Obninsk 249020 (Russian Federation) and International Atomic Energy Agency, Agency' s Laboratories, Seibersdorf A-2444 (Austria)]. E-mail: s.fesenko@iaea.org; Alexakhin, R.M. [Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, Kaluga region, Obninsk 249020 (Russian Federation); Geras' kin, S.A. [Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, Kaluga region, Obninsk 249020 (Russian Federation); Sanzharova, N.I. [Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, Kaluga region, Obninsk 249020 (Russian Federation); Spirin, Ye.V. [Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, Kaluga region, Obninsk 249020 (Russian Federation); Spiridonov, S.I. [Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, Kaluga region, Obninsk 249020 (Russian Federation); Gontarenko, I.A. [Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, Kaluga region, Obninsk 249020 (Russian Federation); Strand, P. [Norwegian Radiation Protection Authority, Oesteras (Norway)

    2005-07-01

    A methodological approach for a comparative assessment of ionising radiation effects on man and non-human species, based on the use of Radiation Impact Factor (RIF) - ratios of actual exposure doses to biota species and man to critical dose is described. As such doses, radiation safety standards limiting radiation exposure of man and doses at which radiobiological effects in non-human species were not observed after the Chernobyl accident, were employed. For the study area within the 30 km ChNPP zone dose burdens to 10 reference biota groups and the population (with and without evacuation) and the corresponding RIFs were calculated. It has been found that in 1986 (early period after the accident) the emergency radiation standards for man do not guarantee adequate protection of the environment, some species of which could be affected more than man. In 1991 RIFs for man were considerably (by factor of 20.0-1.1 x 10{sup 5}) higher compared with those for selected non-human species. Thus, for the long term after the accident radiation safety standards for man are shown to ensure radiation safety for biota as well.

  18. Comparative radiation impact on biota and man in the area affected by the accident at the Chernobyl nuclear power plant

    International Nuclear Information System (INIS)

    A methodological approach for a comparative assessment of ionising radiation effects on man and non-human species, based on the use of Radiation Impact Factor (RIF) - ratios of actual exposure doses to biota species and man to critical dose is described. As such doses, radiation safety standards limiting radiation exposure of man and doses at which radiobiological effects in non-human species were not observed after the Chernobyl accident, were employed. For the study area within the 30 km ChNPP zone dose burdens to 10 reference biota groups and the population (with and without evacuation) and the corresponding RIFs were calculated. It has been found that in 1986 (early period after the accident) the emergency radiation standards for man do not guarantee adequate protection of the environment, some species of which could be affected more than man. In 1991 RIFs for man were considerably (by factor of 20.0-1.1 x 105) higher compared with those for selected non-human species. Thus, for the long term after the accident radiation safety standards for man are shown to ensure radiation safety for biota as well

  19. Does occupational exposure to low-dose ionizing radiation affect bone marrow thrombopoiesis?

    OpenAIRE

    Sayed, Douaa; Abd Elwanis, Mostafa E; Abd Elhameed, Saly Y; Galal, Hanan

    2011-01-01

    Background The biological effects of high levels of radiation exposure are fairly well known, but the effects of low levels of radiation are more difficult to determine because the deterministic effects do not occur at these levels. Methods In order to assess the risk of this exposure on BM thrombopoiesis, we measured reticulated platelets (RP) by flow cytometry in 14 hospital workers (12 technicians and 2 nurses) exposed to low level ionizing radiation in Radiotherapy Department in South Egy...

  20. Individual sensitivity to radiations and DNA repair proficiency: the comet assay contribution

    International Nuclear Information System (INIS)

    Some are hereditary syndromes demonstrate high cancer risk and hypersensitivity in response to exposures to agents such as ultraviolet or ionising radiation, and are characterized by a defective processing of DNA damage. They highlight the importance of the individual risk associated to exposures. The comet assay, a simple technique that detects DNA strand breaks, requires few cells and allows examination of DNA repair capacities in established cell lines, in blood samples or biopsies. The assay has been validated on cellular systems with known repair defects such as xeroderma pigmentosum defective in nucleotide excision repair, on mutant rodent cell lines defective in DNA single strand breaks rejoining (XRCC5/Ku80 and XRCC7/DNAPKcs) (neutral conditions). This assay does not allow to distinguish a defective phenotype in ataxia telangiectasia cells. It shows in homozygous mouse embryo fibroblasts Brca2-/- an impaired DNA double strand break rejoining. Simplicity, rapidity and sensitivity of the alkaline comet assay allow to examine the response of lymphocytes. It has been applied to the analysis of the role of DNA repair in the pathogenesis of collagen diseases, and the involvement of individual DNA repair proficiency in the thyroid tumorigenesis induced in some patients after therapeutic irradiation at childhood has been questioned. Preliminary results of these studies suggest that this type of approach could help for adapting treatment modalities and surveillance in subgroups of patients defective in DNA repair process. It could also have some incidence in the radioprotection field. (author)

  1. Carboxymethyl starch cross-linked by electron beam radiation in presence of acrylic acid sensitizer

    International Nuclear Information System (INIS)

    Carboxymethyl starch (CMS) can be cross-linked by electron beam radiation to form a biocompatible and environment-friendly hydrogel at a high absorbed dose and a condensed CMS concentration. Acrylic acid (AAc) can be used as a sensitizer in order to reduce the absorbed doses to an acceptable certain level. At an absorbed dose of 3-4 kGy, the gel content of crosslinked CMS can be obtained about 50% with 5% (w/w) AAc concentration used. The compressive strength of CMS samples increased with increasing their cross-linked densities due to raising absorbed doses. The swelling ratio of cross-linked CMS was also attainable at a maximum of 50 times in the distilled water. The enzymatic degradation of cross-linked CMS was carried out in acetate buffer pH 4.6 with 0.1% α-amylase enzymatic solution incubated at 40℃ for 6 h. The crosslinked CMS samples were degraded slower than uncrosslinked CMS ones. The results indicated that the highly cross-linked CMS was almost fully degradable when the enzymatic hydrolysis was performed during 6 h. The FT IR spectra of cross-linked CMS in the presence of AAc were examined to observe the carboxyl group of AAc in the structure of cross-linked CMS. The hydrophilic of cross-linked CMS surface was determined by a contact-angle analysis. (authors)

  2. Arsenic trioxide enhances the radiation sensitivity of androgen-dependent and -independent human prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Hui-Wen Chiu

    Full Text Available Prostate cancer is the most common malignancy in men. In the present study, LNCaP (androgen-sensitive human prostate cancer cells and PC-3 cells (androgen-independent human prostate cancer cells were used to investigate the anti-cancer effects of ionizing radiation (IR combined with arsenic trioxide (ATO and to determine the underlying mechanisms in vitro and in vivo. We found that IR combined with ATO increases the therapeutic efficacy compared to individual treatments in LNCaP and PC-3 human prostate cancer cells. In addition, combined treatment showed enhanced reactive oxygen species (ROS generation compared to treatment with ATO or IR alone in PC-3 cells. Combined treatment induced autophagy and apoptosis in LNCaP cells, and mainly induced autophagy in PC-3 cells. The cell death that was induced by the combined treatment was primarily the result of inhibition of the Akt/mTOR signaling pathways. Furthermore, we found that the combined treatment of cells pre-treated with 3-MA resulted in a significant change in AO-positive cells and cytotoxicity. In an in vivo study, the combination treatment had anti-tumor growth effects. These novel findings suggest that combined treatment is a potential therapeutic strategy not only for androgen-dependent prostate cancer but also for androgen-independent prostate cancer.

  3. Sensitivity of Roberts Syndrome Cells to gamma radiation, mitomycin C, and protein synthesis inhibitors

    International Nuclear Information System (INIS)

    Roberts syndrome (RS) is a rare autosomal recessive disorder characterized by pre- and postnatal growth retardation, limb reduction abnormalities, and craniofacial anomalies. Mitotic chromosomes from RS individuals display repulsion of heterochromatin regions or centromere splitting, leading to a railroad-track appearance of mitotic chromosomes. Abnormalities in metaphase duration, anaphase progression, nuclear morphology, and increased frequency of micronucleation have been reported in RS cells. Cells from RS heterozygotes are normal in these respects, and in vitro complementation of the defects in somatic cell hybrids has been reported. Therefore, in preparation for the isolation of cDNAs that complement the RS defect, the authors investigated various drug treatments to identify an agent that specifically involves the growth of RS cells. Based on the cytogenetic and cell biologic findings, they chose agents that increase micronucleation or inhibit protein synthesis. They found that RS cells are hypersensitive to gamma radiation, mitomycin C, G418 and hygromycin B, but not to colcemid or streptonigrin when compared to normal cells. DNA content and cell viability analysis confirmed that the sensitivity to gamma irradiation was primarily due to increased cell death

  4. Control of radiation sensitivity of mammalian cells. Regulation of expression of DNA repair genes

    International Nuclear Information System (INIS)

    This review describes authors' investigations concerning regulation of expression of DNA repair genes for the purpose of control of radiosensitivity of mammalian cells for cancer radiotherapy. One of their experiments concerns the enhancement of sensitivity to radiation and anti-tumor agents by suppressing the expression of mammalian Rad51 gene which playing a central role in recombination repair against DNA double-strand break, by RNA interference (RNAi). Described are the mode of action of RNAi, mechanism of suppression of Rad51 gene expression by it, enhancing effect in radiosensitivity, stable suppression and enhancement by hairpin RNA and its possible usefulness in cancer therapy. The other concerns the histone H2AX gene, which delivering the repair signal post phosphorylation in chromatin against the double-strand break. Experimental results of suppression of the histone H2AX gene by tet-off system, enhancement of radiosensitivity by the suppression and functional recovery by the gene transfer are described, and the radiosensitivity can be thus artificially controlled by tetracycline in authors' F9 2AX (tet/tet) cells. (N.I.)

  5. Silencing of poly(ADP-ribose) glycohydrolase sensitizes lung cancer cells to radiation through the abrogation of DNA damage checkpoint

    Energy Technology Data Exchange (ETDEWEB)

    Nakadate, Yusuke [Shien-Lab, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Department of Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Kodera, Yasuo; Kitamura, Yuka [Shien-Lab, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Tachibana, Taro [Department of Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Tamura, Tomohide [Division of Thoracic Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Koizumi, Fumiaki, E-mail: fkoizumi@ncc.go.jp [Division of Thoracic Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan)

    2013-11-29

    Highlights: •Radiosensitization by PARG silencing was observed in multiple lung cancer cells. •PAR accumulation was enhanced by PARG silencing after DNA damage. •Radiation-induced G2/M arrest and checkpoint activation were impaired by PARG siRNA. -- Abstract: Poly(ADP-ribose) glycohydrolase (PARG) is a major enzyme that plays a role in the degradation of poly(ADP-ribose) (PAR). PARG deficiency reportedly sensitizes cells to the effects of radiation. In lung cancer, however, it has not been fully elucidated. Here, we investigated whether PARG siRNA contributes to an increased radiosensitivity using 8 lung cancer cell lines. Among them, the silencing of PARG induced a radiosensitizing effect in 5 cell lines. Radiation-induced G2/M arrest was largely suppressed by PARG siRNA in PC-14 and A427 cells, which exhibited significantly enhanced radiosensitivity in response to PARG knockdown. On the other hand, a similar effect was not observed in H520 cells, which did not exhibit a radiosensitizing effect. Consistent with a cell cycle analysis, radiation-induced checkpoint signals were not well activated in the PC-14 and A427 cells when treated with PARG siRNA. These results suggest that the increased sensitivity to radiation induced by PARG knockdown occurs through the abrogation of radiation-induced G2/M arrest and checkpoint activation in lung cancer cells. Our findings indicate that PARG could be a potential target for lung cancer treatments when used in combination with radiotherapy.

  6. Evaluation of Factors Affecting the Value of Online Shopping Considering Price Sensitivity and Variety-Seeking of Buyers

    Directory of Open Access Journals (Sweden)

    Mahdi Alhoseini Almodarresi

    2015-09-01

    Full Text Available Ease of access to information, possibility to compare products quickly, and many other facilities that Internet provides for consumers, increase the power of consumers much higher. Internet sellers for the purpose of increasing their sales, often offer lower prices in compare to retailer's price. Nevertheless, the recent studies represent that even price-sensitive customers, avoid shopping from low price online stores. Rather value is considered as the key driver of costumers' decision-making in economic and marketing. Therefore, it is necessary to try to identify those factors affecting online shopping. This research is aimed to study the effective factors on customer's values using survey research method, descriptive-causal type. The research statistical population consists of people who have an experience of on-line shopping at lease for one time. Data were analyzed using structural equation modeling method via LISREL software and partial least squares method via SMART PLS software. The results showed that, although system quality is an effective factor on utilitarian shopping values, information quality have no effect on both utilitarian and hedonic values. Generally, utilitarian and hedonic values could cause to online consumers' satisfaction, and satisfaction significantly could improve repurchase intention. Moreover, the results show the moderating effect of price sensitivity in relation of system quality and information with utilitarian value and also moderating effect of variety-seeking in relation of information quality with hedonic value.

  7. Evaluation of the radiation-sensitizer/protector and/or antioxidant efficiencies using Fricke and PAG dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Meesat, Ridthee; Jay-Gerin, Jean-Paul; Khalil, Abdelouahed; Lepage, Martin [Departement de medecine nucleaire et de radiobiologie, Faculte de medecine et des sciences de la sante, Universite de Sherbrooke, Sherbrooke (Quebec) J1H 5N4 (Canada)], E-mail: Martin.Lepage@USherbrooke.ca

    2009-05-01

    In this study, our aim is to assess the potential of Fricke and polyacrylamide gel (PAG) dosimeters to quantitatively evaluate the efficiency of potential radiation sensitizers/protectors and antioxidants. These compounds are of importance in radiotherapy as well as in disease prevention and promotion of health. The basic principle of the Fricke dosimeter is the radiation-induced oxidation of Fe{sup 2+} to Fe{sup 3+} in an aerated aqueous 0.4 M H{sub 2}SO{sub 4}. The production of ferric ions is most sensitive to the radical species produced in the radiolysis of water. Using this method, we observed that cystamine (one of the best of the known radioprotectors) can prevent oxydation of Fe{sup 2+} from reactive radiolysis species. However, one obvious disadvantage of the Fricke dosimeter is that it operates under highly acidic conditions (pH 0.46), which may degrade biological compounds. In contrast, the pH of the polyacrylamide gel (PAG) dosimeter is almost neutral, such that degradation of compounds is less probable. A change in R{sub 2}-dose sensitivity was observed in the presence of radiosensitizers/radioprotectors and antioxidants. The protective effect of Trolox (a well-known antioxidant) and thiourea (a radioprotector) was readily observed using the PAG dosimeter. Incorporation of iodinated radiation sensitizers such as NaI and an iodine contrast agent led to a quantifiable sensitizer enhancement ratio. These studies suggest that the Fricke and the PAG dosimeters have the potential to evaluate the efficiency of radiation sensitizers/protectors and antioxidants.

  8. Curcumin Sensitizes Hepatocellular Carcinoma Cells to Radiation via Suppression of Radiation-Induced NF-κB Activity

    Directory of Open Access Journals (Sweden)

    Fei-Ting Hsu

    2015-01-01

    Full Text Available The effects and possible underlying mechanism of curcumin combined with radiation in human hepatocellular carcinoma (HCC cells in vitro were evaluated. The effects of curcumin, radiation, and combination of both on cell viability, apoptosis, NF-κB activation, and expressions of NF-κB downstream effector proteins were investigated with 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT, NF-κB reporter gene, mitochondrial membrane potential (MMP, electrophoretic mobility shift (EMSA, and Western blot assays in Huh7-NF-κB-luc2, Hep3B, and HepG2 cells. Effect of I kappa B alpha mutant (IκBαM vector, a specific inhibitor of NF-κB activation, on radiation-induced loss of MMP was also evaluated. Results show that curcumin not only significantly enhances radiation-induced cytotoxicity and depletion of MMP but inhibits radiation-induced NF-κB activity and expressions of NF-κB downstream proteins in HCC cells. IκBαM vector also shows similar effects. In conclusion, we suggest that curcumin augments anticancer effects of radiation via the suppression of NF-κB activation.

  9. Rearrangement of RAG-1 recombinase gene in radiation-sensitive ''wasted'' mice

    International Nuclear Information System (INIS)

    The recent cloning and characterization of recombinase genes (RAG- 1/RAG-2) expressed in lymphoid and possibly central nervous system tissues prompted us to examine expression of these genes in DNA repair-deficient/immunodeficient wasted mice (wst). Our results revealed expression of RAG-1 mRNA was detected in spinal cord or brain from wst/wst mice or their normal littermates (wst/sm-bullet mice). In thymus tissue, a small RAG-1 transcript was detected in wst/wst mice that was not evident in thymus from control mice. In wst/lg-bullet mice, a two-fold increase in RAG-1 mRNA was evident in thymus tissue. RAG-2 mRNA could only be detected in thymus tissue from wst/sm-bullet and not from wst;/wst or parental control BCF1 mice. Southern blots revealed a rearrangement/deletion within the RAG-1 gene of affected wasted mice, not evident in known strain-specific parental or littermate controls. These results support the idea that the RAG-1 gene may map at or near the locus for the wasted mutation. In addition, they suggest the importance of recombinase function in normal immune and central nervous system development as well as the potential contribution of this gene family to the normal repair of radiation-induced DNA damage

  10. Mesenchymal stem cells are sensitive to treatment with kinase inhibitors and ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Nicolay, Nils H.; Debus, Juergen; Huber, Peter E. [Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg (Germany); German Cancer Research Center (dkfz), Department of Molecular and Radiation Oncology, Heidelberg (Germany); Sommer, Eva; Lopez Perez, Ramon; Wirkner, Ute [German Cancer Research Center (dkfz), Department of Molecular and Radiation Oncology, Heidelberg (Germany); Bostel, Tilman [Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg (Germany); Ho, Anthony D.; Saffrich, Rainer [Heidelberg University Hospital, Department of Hematology, Oncology and Rheumatology, Heidelberg (Germany); Lahn, Michael [Lilly Research Laboratories, Oncology Early Clinical Investigation, Indianapolis, IN (United States)

    2014-11-15

    Mesenchymal stem cells (MSCs) can regenerate damaged tissues and may therefore be of importance for normal tissue repair after cancer treatment. Small molecule receptor kinase inhibitors (RKIs) have recently been introduced into cancer treatment. However, the influence of these drugs - particularly in combination with radiotherapy - on the survival of MSCs is largely unknown. The sensitivity of human primary MSCs from healthy volunteers and primary human fibroblast cells to small molecule kinase inhibitors of the vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and transforming growth factor β (TGFβ) receptors, as well to inhibitors of c-Kit, was examined in combination with ionizing radiation (IR); cell survival and proliferation were assessed. Expression patterns of different kinase receptors and ligands were investigated using gene arrays. MSCs were highly sensitive to the tyrosine kinase inhibitors SU14816 (imatinib) and SU11657 (sunitinib), but showed only moderate sensitivity to the selective TGFβ receptor 1 inhibitor LY2109761. Primary adult human fibroblasts were comparably resistant to all three inhibitors. The addition of IR had an additive or supra-additive effect in the MSCs, but this was not the case for differentiated fibroblasts. Proliferation was markedly reduced in MSCs following kinase inhibition, both with and without IR. Gene expression analysis revealed high levels of the PDGF α and β receptors, and lower levels of the TGFβ receptor 2 and Abl kinase. IR did not alter the expression of kinase receptors or their respective ligands in either MSCs or adult fibroblasts. These data show that MSCs are highly sensitive to RKIs and combination treatments incorporating IR. Expression analyses suggest that high levels of PDGF receptors may contribute to this effect. (orig.) [German] Mesenchymale Stammzellen (MSCs) koennen die Geweberegeneration unterstuetzen und haben daher moeglicherweise eine Rolle bei der Reparatur

  11. Ionizing radiation affects generation of MART-1-specific cytotoxic T cell responses by dendritic cells

    International Nuclear Information System (INIS)

    Full text: The human MART-1/Melan-A (MART-1) melanoma tumor antigen is known to be recognized by cytotoxic T lymphocytes (CTLs) and several groups are using this target for clinical immunotherapy. Most approaches use dendritic cells (DCs) that are potent antigen presentation cells for initiating CTL responses. In order for CTL recognition to occur, DCs must display 9-residue antigenic peptides on MHC class I molecules. These peptides are generated by proteasome degradation and then transported through the endoplasmic reticulum to the cell surface where they stabilize MHC class I expression. Our previous data showed that irradiation inhibits proteasome function and, therefore, we hypothesized that irradiation may inhibit antigen processing and CTL activation, as has been shown for proteasome inhibitors. To study the importance of irradiation effects on DCs, we studied the generation MART-1-specific CTL responses. Preliminary data showed that irradiation of murine bone marrow derived DCs did not affect expression of MHC class I, II, CD80, or CD86, as assessed by flow cytometric analyses 24-hour after irradiation. The effect of irradiation on MART-1 antigen processing by DCs was evaluated using DC transduced with adenovirus MART-1 (AdVMART1). C57BL/6 mice were immunized with AdVMART1 transduced DCs, with and without prior irradiation. IFN-γ production was measured by ELISPOT assays after 10-14 days of immunization. Prior radiation treatment resulted in a significant decrease in MART-1-specific T cell responses. The ability of irradiated and non-irradiated AdVMART1/DC vaccines to protect mice against growth of murine B16 tumors, which endogenously express murine MART-1, was also examined. AdVMART1/DC vaccination protected C57BL/6 mice against challenge with viable B16 melanoma cells while DCs irradiated (10 Gy) prior to AdVMART1 transduction abrogated protection. These results suggest that proteasome inhibition in DCs by irradiation may be a possible pathway in

  12. Locally Targeted Delivery of a Micron-Size Radiation Therapy Source Using Temperature-Sensitive Hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yusung, E-mail: yusung-kim@uiowa.edu [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Seol, Dong Rim [Department of Orthopaedic Surgery, The University of Iowa, Iowa City, Iowa (United States); Mohapatra, Sucheta [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States); Sunderland, John J. [Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Schultz, Michael K. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Domann, Frederick E. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Surgery, The University of Iowa, Iowa City, Iowa (United States); Lim, Tae-Hong [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States)

    2014-04-01

    Purpose: To propose a novel radiation therapy (RT) delivery modality: locally targeted delivery of micron-size RT sources by using temperature-sensitive hydrogel (RT-GEL) as an injectable vehicle. Methods and Materials: Hydrogel is a water-like liquid at room temperature but gels at body temperature. Two US Food and Drug Administration-approved polymers were synthesized. Indium-111 (In-111) was used as the radioactive RT-GEL source. The release characteristics of In-111 from polymerized RT-GEL were evaluated. The injectability and efficacy of RT-GEL delivery to human breast tumor were tested using animal models with control datasets of RT-saline injection. As proof-of-concept studies, a total of 6 nude mice were tested by injecting 4 million tumor cells into their upper backs after a week of acclimatization. Three mice were injected with RT-GEL and 3 with RT-saline. Single-photon emission computed tomography (SPECT) and CT scans were performed on each mouse at 0, 24, and 48 h after injection. The efficacy of RT-GEL was determined by comparison with that of the control datasets by measuring kidney In-111 accumulation (mean nCi/cc), representing the distant diffusion of In-111. Results: RT-GEL was successfully injected into the tumor by using a 30-gauge needle. No difficulties due to polymerization of hydrogel during injection and intratumoral pressure were observed during RT-GEL injection. No back flow occurred for either RT-GEL or RT-saline. The residual tumor activities of In-111 were 49% at 24 h (44% at 48 h, respectively) for RT-GEL and 29% (22%, respectively) for RT-saline. Fused SPECT-CT images of RT-saline showed considerable kidney accumulation of In-111 (2886%, 261%, and 262% of RT-GEL at 0, 24, and 48 h, respectively). Conclusions: RT-GEL was successfully injected and showed much higher residual tumor activity: 170% (200%, respectively), than that of RT-saline at 24 h (48 h, respectively) after injection with a minimal accumulation of In-111 to the

  13. Locally Targeted Delivery of a Micron-Size Radiation Therapy Source Using Temperature-Sensitive Hydrogel

    International Nuclear Information System (INIS)

    Purpose: To propose a novel radiation therapy (RT) delivery modality: locally targeted delivery of micron-size RT sources by using temperature-sensitive hydrogel (RT-GEL) as an injectable vehicle. Methods and Materials: Hydrogel is a water-like liquid at room temperature but gels at body temperature. Two US Food and Drug Administration-approved polymers were synthesized. Indium-111 (In-111) was used as the radioactive RT-GEL source. The release characteristics of In-111 from polymerized RT-GEL were evaluated. The injectability and efficacy of RT-GEL delivery to human breast tumor were tested using animal models with control datasets of RT-saline injection. As proof-of-concept studies, a total of 6 nude mice were tested by injecting 4 million tumor cells into their upper backs after a week of acclimatization. Three mice were injected with RT-GEL and 3 with RT-saline. Single-photon emission computed tomography (SPECT) and CT scans were performed on each mouse at 0, 24, and 48 h after injection. The efficacy of RT-GEL was determined by comparison with that of the control datasets by measuring kidney In-111 accumulation (mean nCi/cc), representing the distant diffusion of In-111. Results: RT-GEL was successfully injected into the tumor by using a 30-gauge needle. No difficulties due to polymerization of hydrogel during injection and intratumoral pressure were observed during RT-GEL injection. No back flow occurred for either RT-GEL or RT-saline. The residual tumor activities of In-111 were 49% at 24 h (44% at 48 h, respectively) for RT-GEL and 29% (22%, respectively) for RT-saline. Fused SPECT-CT images of RT-saline showed considerable kidney accumulation of In-111 (2886%, 261%, and 262% of RT-GEL at 0, 24, and 48 h, respectively). Conclusions: RT-GEL was successfully injected and showed much higher residual tumor activity: 170% (200%, respectively), than that of RT-saline at 24 h (48 h, respectively) after injection with a minimal accumulation of In-111 to the

  14. A Polymorphism Within the Promoter of the TGFβ1 Gene Is Associated With Radiation Sensitivity Using an Objective Radiologic Endpoint

    International Nuclear Information System (INIS)

    Purpose: To evaluate whether single nucleotide polymorphisms (SNPs) in the transforming growth factor-β1 (TGFβ1) gene are associated with radiation sensitivity using an objective radiologic endpoint. Methods and Materials: Preradiation therapy and serial postradiation therapy single photon emission computed tomography (SPECT) lung perfusion scans were obtained in patients undergoing treatment for lung cancer. Serial blood samples were obtained to measure circulating levels of TGFβ1. Changes in regional perfusion were related to regional radiation dose yielding a patient-specific dose–response curve, reflecting the patient’s inherent sensitivity to radiation therapy. Six TGFβ1 SNPs (-988, -800, -509, 869, 941, and 1655) were assessed using high-resolution melting assays and DNA sequencing. The association between genotype and slope of the dose–response curve, and genotype and TGFβ1 ratio (4-week/preradiation therapy), was analyzed using the Kruskal-Wallis test. Results: 39 white patients with preradiation therapy and ≥6-month postradiation therapy SPECT scans and blood samples were identified. Increasing slope of the dose–response curve was associated with the C(-509)T SNP (p = 0.035), but not the other analyzed SNPs. This SNP was also associated with higher TGFβ1 ratios. Conclusions: This study suggests that a polymorphism within the promoter of the TGFβ1 gene is associated with increased radiation sensitivity (defined objectively by dose-dependent changes in SPECT lung perfusion).

  15. Factors affecting the mortality of Sitophilus oryzae L. (Coleoptera: Curculionidae) due to gamma radiation

    International Nuclear Information System (INIS)

    Sitophilus oryzae, popularly known as rice weevil, is a cosmopolitan pest infesting a wide range of stored products. Two week-old adults were irradiated with gamma rays of low doses (20-100 Gy with an increment of 20) and medium doses (250-1,000 Gy with an interval of 250). Weevils exposed to 40 Gy and above were inactive and moribund within five days after irradiation. Exposure with 100 Gy caused 100% mortality of males and 94% females on 22 days after irradiation as against 4% in the control. Longevity of both sexes could be curtailed significantly due to the treatment of medium doses. Mortality of male and female exposed to 250 Gy was 70 and 78% respectively on 14 days after irradiation. However, on 10 days after irradiation, no live weevils could be noticed in the batches treated with 1,000 Gy. Weevils exposed to 1,000 Gy were observed to be sluggish and reluctant to feed. It has been reported that irrespective of the age, reproductive potential of both sexes was significantly affected due to the exposure of 30 and 50 Gy, but did not affect significantly when treated with 10 Gy. The behaviour of rice weevils to move en mass upward whenever its colony was disturbed, was absent in the case of weevils treated with doses of 50 Gy and above. Food intake of irradiated weevils was studied by providing eosine (1%) stained cassava chips. Two hours after feeding, weevils were dissected under binocular microscope and the intestine was observed. Midgut of the normal and 20 Gy treated weevils appeared red due to the presence of stained food. Until 5 days after irradiation, presence of food in the midgut of weevils exposed to 50 Gy was as normal as in untreated weevils. Later the food intake reduced considerably leading to their death. Consumption was almost inhibited in the 100 Gy exposed weevils and hence the intestine was observed empty. Weevils treated with 10, 25, 50, 75 and 100 Gy were provided with cassava chips for feeding and their weight was monitored daily. A

  16. In vivo sensitivity of the embryonic and adult neural stem cell compartments to low-dose radiation.

    Science.gov (United States)

    Barazzuol, Lara; Jeggo, Penny A

    2016-08-01

    The embryonic brain is radiation-sensitive, with cognitive deficits being observed after exposure to low radiation doses. Exposure of neonates to radiation can cause intracranial carcinogenesis. To gain insight into the basis underlying these outcomes, we examined the response of the embryonic, neonatal and adult brain to low-dose radiation, focusing on the neural stem cell compartments. This review summarizes our recent findings. At E13.5-14.5 the embryonic neocortex encompasses rapidly proliferating stem and progenitor cells. Exploiting mice with a hypomorphic mutation in DNA ligase IV (Lig4(Y288C) ), we found a high level of DNA double-strand breaks (DSBs) at E14.5, which we attribute to the rapid proliferation. We observed endogenous apoptosis in Lig4(Y288C) embryos and in WT embryos following exposure to low radiation doses. An examination of DSB levels and apoptosis in adult neural stem cell compartments, the subventricular zone (SVZ) and the subgranular zone (SGZ) revealed low DSB levels in Lig4(Y288C) mice, comparable with the levels in differentiated neuronal tissues. We conclude that the adult SVZ does not incur high levels of DNA breakage, but sensitively activates apoptosis; apoptosis was less sensitively activated in the SGZ, and differentiated neuronal tissues did not activate apoptosis. P5/P15 mice showed intermediate DSB levels, suggesting that DSBs generated in the embryo can be transmitted to neonates and undergo slow repair. Interestingly, this analysis revealed a stage of high endogenous apoptosis in the neonatal SVZ. Collectively, these studies reveal that the adult neural stem cell compartment, like the embryonic counterpart, can sensitively activate apoptosis. PMID:27125639

  17. Role of membrane Hsp70 in radiation sensitivity of tumor cells

    International Nuclear Information System (INIS)

    The major stress-inducible heat shock protein 70 (Hsp70) is frequently overexpressed in the cytosol and integrated in the plasma membrane of tumor cells via lipid anchorage. Following stress such as non-lethal irradiation Hsp70 synthesis is up-regulated. Intracellular located Hsp70 is known to exert cytoprotective properties, however, less is known about membrane (m)Hsp70. Herein, we investigate the role of mHsp70 in the sensitivity towards irradiation in tumor sublines that differ in their cytosolic and/or mHsp70 levels. The isogenic human colon carcinoma sublines CX+ with stable high and CX− with stable low expression of mHsp70 were generated by fluorescence activated cell sorting, the mouse mammary carcinoma sublines 4 T1 (4 T1 ctrl) and Hsp70 knock-down (4 T1 Hsp70 KD) were produced using the CRISPR/Cas9 system, and the Hsp70 down-regulation in human lung carcinoma sublines H1339 ctrl/H1339 HSF-1 KD and EPLC-272H ctrl/EPLC-272H HSF-1 KD was achieved by small interfering (si)RNA against Heat shock factor 1 (HSF-1). Cytosolic and mHsp70 was quantified by Western blot analysis/ELISA and flow cytometry; double strand breaks (DSBs) and apoptosis were measured by flow cytometry using antibodies against γH2AX and real-time PCR (RT-PCR) using primers and antibodies directed against apoptosis related genes; and radiation sensitivity was determined using clonogenic cell surviving assays. CX+/CX− tumor cells exhibited similar cytosolic but differed significantly in their mHsp70 levels, 4 T1 ctrl/4 T1 Hsp70 KD cells showed significant differences in their cytosolic and mHsp70 levels and H1339 ctrl/H1339 HSF-1 KD and EPLC-272H ctrl/EPLC-272H HSF-1 KD lung carcinoma cell sublines had similar mHsp70 but significantly different cytosolic Hsp70 levels. γH2AX was significantly up-regulated in irradiated CX− and 4 T1 Hsp70 KD with low basal mHsp70 levels, but not in their mHsp70 high expressing counterparts, irrespectively of their cytosolic Hsp70 content. After

  18. Deficient Expression of Aldehyde Dehydrogenase 1A1 Is Consistent with Increased Sensitivity of Gorlin Syndrome Patients to Radiation Carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Aaron T.; Magnaldo, Thierry; Sontag, Ryan L.; Anderson, Lindsey N.; Sadler, Natalie C.; Piehowski, Paul D.; Gache, Yannick; Weber, Thomas J.

    2015-06-01

    Human phenotypes that are highly susceptible to radiation carcinogenesis have been identified. Sensitive phenotypes often display robust regulation of molecular features that modify biological response, which can facilitate identification of relevant pathways/networks. Here we interrogate primary dermal fibroblasts isolated from Gorlin syndrome patients (GDFs), who display a pronounced tumorigenic response to radiation, in comparison to normal human dermal fibroblasts (NHDFs). Our approach exploits newly developed thiol-reactive probes with a flexible click chemistry functional group to define changes in protein thiol profiles in live cell studies, which minimizes artifacts associated with cell lysis. We observe qualitative differences in protein thiol profiles by SDS-PAGE analysis when detection by iodoacetamide vs maleimide probe chemistries are compared, and pretreatment of cells with hydrogen peroxide eliminates detection of the majority of SDS-PAGE bands. Redox probes revealed deficient expression of an apparent 55 kDa protein thiol in GDFs from independent donors, compared with NHDFs. Proteomics tentatively identified this protein as aldehyde dehydrogenase 1A1 (ALDH1A1), a key enzyme regulating retinoic acid synthesis, and this deficiency was confirmed by Western blot. Redox probes revealed additional protein thiol differences between GDFs and NHDFs, including radiation responsive annexin family members. Our results indicate a multifactorial basis for the unusual sensitivity of Gorlin syndrome to radiation carcinogenesis, and the pathways identified have plausible implications for radiation health effects.

  19. Sensitivity of aerosol optical thickness and aerosol direct radiative effect to relative humidity

    Directory of Open Access Journals (Sweden)

    H. Bian

    2009-04-01

    Full Text Available We present a sensitivity study of the effects of spatial and temporal resolution of atmospheric relative humidity (RH on calculated aerosol optical thickness (AOT and the aerosol direct radiative effects (DRE in a global model. We carry out different modeling experiments using the same aerosol fields simulated in the Global Modeling Initiative (GMI model at a resolution of 2° latitude by 2.5° longitude, using time-averaged fields archived every three hours by the Goddard Earth Observation System Version 4 (GEOS-4, but we change the horizontal and temporal resolution of the relative humidity fields. We find that, on a global average, the AOT calculated using RH at a 1°×1.25° horizontal resolution is 11% higher than that using RH at a 2°×2.5° resolution, and the corresponding DRE at the top of the atmosphere is 8–9% and 15% more negative (i.e., more cooling for total aerosols and anthropogenic aerosol alone, respectively, in the finer spatial resolution case. The difference is largest over surface escarpment regions (e.g. >200% over the Andes Mountains where RH varies substantially with surface terrain. The largest zonal mean AOT difference occurs at 50–60° N (16–21%, where AOT is also relatively larger. A similar impact is also found when the time resolution of RH is increased. This increase of AOT and aerosol cooling with the increase of model resolution is due to the highly non-linear relationship between RH and the aerosol mass extinction efficiency (MEE at high RH (>80%. Our study is a specific example of the uncertainty in model results highlighted by multi-model comparisons such as AeroCom, and points out one of the many inter-model differences that can contribute to the overall spread among models.

  20. Female reproductive function in areas affected by radiation after the Chernobyl power station accident

    OpenAIRE

    Kulakov, V. I.; Sokur, T. N.; Volobuev, A. I.; Tzibulskaya, I. S.; Malisheva, V. A.; Zikin, B. I.; Ezova, L. C.; Belyaeva, L. A.; Bonartzev, P. D.; Speranskaya, N. V.; Tchesnokova, J. M.; Matveeva, N. K.; Kaliznuk, E. S.; Miturova, L. B.; Orlova, N. S.

    1993-01-01

    This paper reports the results of a comprehensive survey of the effects of the accidental release of radiation caused by the accident at the Chernobyl nuclear power station in April 1986. The accident and the resulting release of radiation and radioactive products into the atmosphere produced the most serious environmental contamination so far recorded. We have concentrated on evaluating the outcomes and health risks to women, their reproductive situation, and consequences for their progeny. ...

  1. Radiation. What it is, how it affects us and what we can do about it

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, J.H.

    1986-01-01

    The basic facts about radiation are explained, along with some simple and natural ways of combating its ill-effects, based on ancient healing wisdom as well as the latest biochemical and technological research. Details are also given of the diet that saved thousands of lives in Nagasaki after the Atomic bomb attack. Special comment is made on the use of radiation for food processing. (U.K.).

  2. How Galactic Cosmic Ray models affect the estimation of radiation exposure in space

    Science.gov (United States)

    Mrigakshi, Alankrita Isha; Matthiä, Daniel; Berger, Thomas; Reitz, Günther; Wimmer-Schweingruber, Robert F.

    2013-03-01

    The radiation environment in space is a major concern for human spaceflight because of the adverse effects of high levels of radiation on astronauts' health. Therefore, it is essential to perform radiation risk assessments already during the concept studies of a manned mission. Galactic Cosmic Rays (GCR) have been identified to be one of the primary sources of radiation exposure in space.This work presents an evaluation of the radiation exposure caused by GCR between 1970 and 2011 in near-Earth interplanetary space and at the orbit of the International Space Station (ISS) by making numerical simulations with the Monte-Carlo framework GEANT4. Commonly used GCR models - CREME96, CREME2009 and Badhwar-O'Neill2010 are used to describe the GCR spectra and the differences arising from the application of these different models in terms of absorbed dose and dose equivalent rates are investigated. Additionally, the depth distribution of the dose quantities and the relative contribution of particles with different energies to the total exposure during solar maximum and minimum conditions are studied.The differences in the spectra, described by the models, result in considerable differences in the estimation of the radiation exposure.

  3. SU-E-T-146: Effects of Uncertainties of Radiation Sensitivity of Biological Modelling for Treatment Planning

    International Nuclear Information System (INIS)

    Purpose: The aim of this study was to evaluate the distribution of uncertainty of cell survival by radiation, and assesses the usefulness of stochastic biological model applying for gaussian distribution. Methods: For single cell experiments, exponentially growing cells were harvested from the standard cell culture dishes by trypsinization, and suspended in test tubes containing 1 ml of MEM(2x106 cells/ml). The hypoxic cultures were treated with 95% N2−5% CO2 gas for 30 minutes. In vitro radiosensitization was also measured in EMT6/KU single cells to add radiosensitizer under hypoxic conditions. X-ray irradiation was carried out by using an Xray unit (Hitachi X-ray unit, model MBR-1505R3) with 0.5 mm Al/1.0 mm Cu filter, 150 kV, 4 Gy/min). In vitro assay, cells on the dish were irradiated with 1 Gy to 24 Gy, respectively. After irradiation, colony formation assays were performed. Variations of biological parameters were investigated at standard cell culture(n=16), hypoxic cell culture(n=45) and hypoxic cell culture(n=21) with radiosensitizers, respectively. The data were obtained by separate schedule to take account for the variation of radiation sensitivity of cell cycle. Results: At standard cell culture, hypoxic cell culture and hypoxic cell culture with radiosensitizers, median and standard deviation of alpha/beta ratio were 37.1±73.4 Gy, 9.8±23.7 Gy, 20.7±21.9 Gy, respectively. Average and standard deviation of D50 were 2.5±2.5 Gy, 6.1±2.2 Gy, 3.6±1.3 Gy, respectively. Conclusion: In this study, we have challenged to apply these uncertainties of parameters for the biological model. The variation of alpha values, beta values, D50 as well as cell culture might have highly affected by probability of cell death. Further research is in progress for precise prediction of the cell death as well as tumor control probability for treatment planning

  4. SU-E-T-146: Effects of Uncertainties of Radiation Sensitivity of Biological Modelling for Treatment Planning

    Energy Technology Data Exchange (ETDEWEB)

    Oita, M [Department of Radiological Technology, Graduate School of Health Sciences, Okayama University (Japan); Department of Life System, Institute of Technology and Science, Graduate School, The Tokushima University (Japan); Uto, Y; Hori, H [Department of Life System, Institute of Technology and Science, Graduate School, The Tokushima University (Japan); Tominaga, M [Department of Radiological Technology, Institute of Health Biosciences, Graduate School, The Tokushima University (Japan); Sasaki, M [Department of Radiology, Tokushima University Hospital (Japan)

    2014-06-01

    Purpose: The aim of this study was to evaluate the distribution of uncertainty of cell survival by radiation, and assesses the usefulness of stochastic biological model applying for gaussian distribution. Methods: For single cell experiments, exponentially growing cells were harvested from the standard cell culture dishes by trypsinization, and suspended in test tubes containing 1 ml of MEM(2x10{sup 6} cells/ml). The hypoxic cultures were treated with 95% N{sub 2}−5% CO{sub 2} gas for 30 minutes. In vitro radiosensitization was also measured in EMT6/KU single cells to add radiosensitizer under hypoxic conditions. X-ray irradiation was carried out by using an Xray unit (Hitachi X-ray unit, model MBR-1505R3) with 0.5 mm Al/1.0 mm Cu filter, 150 kV, 4 Gy/min). In vitro assay, cells on the dish were irradiated with 1 Gy to 24 Gy, respectively. After irradiation, colony formation assays were performed. Variations of biological parameters were investigated at standard cell culture(n=16), hypoxic cell culture(n=45) and hypoxic cell culture(n=21) with radiosensitizers, respectively. The data were obtained by separate schedule to take account for the variation of radiation sensitivity of cell cycle. Results: At standard cell culture, hypoxic cell culture and hypoxic cell culture with radiosensitizers, median and standard deviation of alpha/beta ratio were 37.1±73.4 Gy, 9.8±23.7 Gy, 20.7±21.9 Gy, respectively. Average and standard deviation of D{sub 50} were 2.5±2.5 Gy, 6.1±2.2 Gy, 3.6±1.3 Gy, respectively. Conclusion: In this study, we have challenged to apply these uncertainties of parameters for the biological model. The variation of alpha values, beta values, D{sub 50} as well as cell culture might have highly affected by probability of cell death. Further research is in progress for precise prediction of the cell death as well as tumor control probability for treatment planning.

  5. Using synchrotron radiation angiography with a highly sensitive detector to identify impaired peripheral perfusion in rat pulmonary emphysema

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hiromichi [University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan); Matsushita, Shonosuke, E-mail: shomatsu@md.tsukuba.ac.jp [University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan); Tsukuba University of Technology, Tsukuba, Ibaraki 305-8521 (Japan); Hyodo, Kazuyuki [High Energy Accelerator Research Organization, KEK, Tsukuba, Ibaraki 305-0801 (Japan); Sato, Yukio; Sakakibara, Yuzuru [University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan)

    2013-03-01

    Synchrotron radiation angiography with a HARP detector made it possible to evaluate impaired pulmonary microcirculation in pulmonary emphysema by means of high sensitivity. Owing to limitations in spatial resolution and sensitivity, it is difficult for conventional angiography to detect minute changes of perfusion in diffuse lung diseases, including pulmonary emphysema (PE). However, a high-gain avalanche rushing amorphous photoconductor (HARP) detector can give high sensitivity to synchrotron radiation (SR) angiography. SR angiography with a HARP detector provides high spatial resolution and sensitivity in addition to time resolution owing to its angiographic nature. The purpose of this study was to investigate whether this SR angiography with a HARP detector could evaluate altered microcirculation in PE. Two groups of rats were used: group PE and group C (control). Transvenous SR angiography with a HARP detector was performed and histopathological findings were compared. Peak density of contrast material in peripheral lung was lower in group PE than group C (p < 0.01). The slope of the linear regression line in scattering diagrams was also lower in group PE than C (p < 0.05). The correlation between the slope and extent of PE in histopathology showed significant negative correlation (p < 0.05, r = 0.61). SR angiography with a HARP detector made it possible to identify impaired microcirculation in PE by means of its high spatial resolution and sensitivity.

  6. Using synchrotron radiation angiography with a highly sensitive detector to identify impaired peripheral perfusion in rat pulmonary emphysema

    International Nuclear Information System (INIS)

    Synchrotron radiation angiography with a HARP detector made it possible to evaluate impaired pulmonary microcirculation in pulmonary emphysema by means of high sensitivity. Owing to limitations in spatial resolution and sensitivity, it is difficult for conventional angiography to detect minute changes of perfusion in diffuse lung diseases, including pulmonary emphysema (PE). However, a high-gain avalanche rushing amorphous photoconductor (HARP) detector can give high sensitivity to synchrotron radiation (SR) angiography. SR angiography with a HARP detector provides high spatial resolution and sensitivity in addition to time resolution owing to its angiographic nature. The purpose of this study was to investigate whether this SR angiography with a HARP detector could evaluate altered microcirculation in PE. Two groups of rats were used: group PE and group C (control). Transvenous SR angiography with a HARP detector was performed and histopathological findings were compared. Peak density of contrast material in peripheral lung was lower in group PE than group C (p < 0.01). The slope of the linear regression line in scattering diagrams was also lower in group PE than C (p < 0.05). The correlation between the slope and extent of PE in histopathology showed significant negative correlation (p < 0.05, r = 0.61). SR angiography with a HARP detector made it possible to identify impaired microcirculation in PE by means of its high spatial resolution and sensitivity

  7. Relationship Between Chromatin Structure and Sensitivity to Molecularly Targeted Auger Electron Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: The open structure of euchromatin renders it susceptible to DNA damage by ionizing radiation (IR) compared with compact heterochromatin. The effect of chromatin configuration on the efficacy of Auger electron radiotherapy was investigated. Methods and Materials: Chromatin structure was altered in MDA-MB-468 and 231-H2N human breast cancer cells by suberoylanilide hydroxamic acid (SAHA), 5-aza-2-deoxycytidine, or hypertonic treatment. The extent and duration of chromatin structural changes were evaluated using the micrococcal nuclease assay. DNA damage (γH2AX assay) and clonogenic survival were evaluated after exposure to 111In-DTPA-hEGF, an Auger electron-emitting radiopharmaceutical, or IR. The intracellular distribution of 111In-DTPA-hEGF after chromatin modification was investigated in cell fractionation experiments. Results: Chromatin remained condensed for up to 20 minutes after NaCl and in a relaxed state 24 hours after SAHA treatment. The number of γH2AX foci per cell was greater in MDA-MB-468 and 231-H2N cells after IR (0.5 Gy) plus SAHA (1 μM) compared with IR alone (16 ± 0.6 and 14 ± 0.3 vs. 12 ± 0.4 and 11 ± 0.2, respectively). More γH2AX foci were observed in MDA-MB-468 and 231-H2N cells exposed to 111In-DTPA-hEGF (6 MBq/μg) plus SAHA vs. 111In-DTPA-hEGF alone (11 ± 0.3 and 12 ± 0.7 vs. 9 ± 0.4 and 7 ± 0.3, respectively). 5-aza-2-deoxycytidine enhanced the DNA damage caused by IR and 111In-DTPA-hEGF. Clonogenic survival was reduced in MDA-MB-468 and 231-H2N cells after IR (6 Gy) plus SAHA (1 μM) vs. IR alone (0.6% ± 0.01 and 0.3% ± 0.2 vs. 5.8% ± 0.2 and 2% ± 0.1, respectively) and after 111In-DTPA-hEGF plus SAHA compared to 111In-DTPA-hEGF alone (21% ± 0.4% and 19% ± 4.6 vs. 33% ± 2.3 and 32% ± 3.7). SAHA did not affect 111In-DTPA-hEGF nuclear localization. Hypertonic treatment resulted in fewer γH2AX foci per cell after IR and 111In-DTPA-hEGF compared to controls but did not significantly alter clonogenic survival

  8. Photosynthesis of two Arctic macroalgae under different ambient radiation levels and their sensitivity to enhanced UV radiation

    NARCIS (Netherlands)

    Brouwer, P.E.M.; Bischof, K.; Hanelt, D.; Kromkamp, J.C.

    2000-01-01

    The change in optimal quantum efficiency (F-v/F-m) of the Arctic species Laminaria saccharina and Palmaria palmata was investigated in a long-term experiment in situ under different radiation levels during the summer of 1997 in the Kongsfjord (Ny-Alesund, Spitsbergen, Norway, 78 degrees 55.5'N, 11 d

  9. Aboveground allometric models for freeze-affected black mangroves (Avicennia germinans: equations for a climate sensitive mangrove-marsh ecotone.

    Directory of Open Access Journals (Sweden)

    Michael J Osland

    Full Text Available Across the globe, species distributions are changing in response to climate change and land use change. In parts of the southeastern United States, climate change is expected to result in the poleward range expansion of black mangroves (Avicennia germinans at the expense of some salt marsh vegetation. The morphology of A. germinans at its northern range limit is more shrub-like than in tropical climes in part due to the aboveground structural damage and vigorous multi-stem regrowth triggered by extreme winter temperatures. In this study, we developed aboveground allometric equations for freeze-affected black mangroves which can be used to quantify: (1 total aboveground biomass; (2 leaf biomass; (3 stem plus branch biomass; and (4 leaf area. Plant volume (i.e., a combination of crown area and plant height was selected as the optimal predictor of the four response variables. We expect that our simple measurements and equations can be adapted for use in other mangrove ecosystems located in abiotic settings that result in mangrove individuals with dwarf or shrub-like morphologies including oligotrophic and arid environments. Many important ecological functions and services are affected by changes in coastal wetland plant community structure and productivity including carbon storage, nutrient cycling, coastal protection, recreation, fish and avian habitat, and ecosystem response to sea level rise and extreme climatic events. Coastal scientists in the southeastern United States can use the identified allometric equations, in combination with easily obtained and non-destructive plant volume measurements, to better quantify and monitor ecological change within the dynamic, climate sensitive, and highly-productive mangrove-marsh ecotone.

  10. Aboveground allometric models for freeze-affected black mangroves (Avicennia germinans): equations for a climate sensitive mangrove-marsh ecotone.

    Science.gov (United States)

    Osland, Michael J; Day, Richard H; Larriviere, Jack C; From, Andrew S

    2014-01-01

    Across the globe, species distributions are changing in response to climate change and land use change. In parts of the southeastern United States, climate change is expected to result in the poleward range expansion of black mangroves (Avicennia germinans) at the expense of some salt marsh vegetation. The morphology of A. germinans at its northern range limit is more shrub-like than in tropical climes in part due to the aboveground structural damage and vigorous multi-stem regrowth triggered by extreme winter temperatures. In this study, we developed aboveground allometric equations for freeze-affected black mangroves which can be used to quantify: (1) total aboveground biomass; (2) leaf biomass; (3) stem plus branch biomass; and (4) leaf area. Plant volume (i.e., a combination of crown area and plant height) was selected as the optimal predictor of the four response variables. We expect that our simple measurements and equations can be adapted for use in other mangrove ecosystems located in abiotic settings that result in mangrove individuals with dwarf or shrub-like morphologies including oligotrophic and arid environments. Many important ecological functions and services are affected by changes in coastal wetland plant community structure and productivity including carbon storage, nutrient cycling, coastal protection, recreation, fish and avian habitat, and ecosystem response to sea level rise and extreme climatic events. Coastal scientists in the southeastern United States can use the identified allometric equations, in combination with easily obtained and non-destructive plant volume measurements, to better quantify and monitor ecological change within the dynamic, climate sensitive, and highly-productive mangrove-marsh ecotone. PMID:24971938

  11. Aboveground allometric models for freeze-affected black mangroves (Avicennia germinans): equations for a climate sensitive mangrove-marsh ecotone

    Science.gov (United States)

    Osland, Michael J.; Day, Richard H.; Larriviere, Jack C.; From, Andrew S.

    2014-01-01

    Across the globe, species distributions are changing in response to climate change and land use change. In parts of the southeastern United States, climate change is expected to result in the poleward range expansion of black mangroves (Avicennia germinans) at the expense of some salt marsh vegetation. The morphology of A. germinans at its northern range limit is more shrub-like than in tropical climes in part due to the aboveground structural damage and vigorous multi-stem regrowth triggered by extreme winter temperatures. In this study, we developed aboveground allometric equations for freeze-affected black mangroves which can be used to quantify: (1) total aboveground biomass; (2) leaf biomass; (3) stem plus branch biomass; and (4) leaf area. Plant volume (i.e., a combination of crown area and plant height) was selected as the optimal predictor of the four response variables. We expect that our simple measurements and equations can be adapted for use in other mangrove ecosystems located in abiotic settings that result in mangrove individuals with dwarf or shrub-like morphologies including oligotrophic and arid environments. Many important ecological functions and services are affected by changes in coastal wetland plant community structure and productivity including carbon storage, nutrient cycling, coastal protection, recreation, fish and avian habitat, and ecosystem response to sea level rise and extreme climatic events. Coastal scientists in the southeastern United States can use the identified allometric equations, in combination with easily obtained and non-destructive plant volume measurements, to better quantify and monitor ecological change within the dynamic, climate sensitive, and highly-productive mangrove-marsh ecotone.

  12. Pomegranate Supplementation Improves Affective and Motor Behavior in Mice after Radiation Exposure

    Directory of Open Access Journals (Sweden)

    Melissa S. Dulcich

    2013-01-01

    Full Text Available Currently, NASA has plans for extended space travel, and previous research indicates that space radiation can have negative effects on cognitive skills as well as physical and mental health. With long-term space travel, astronauts will be exposed to greater radiation levels. Research shows that an antioxidant-enriched diet may offer some protection against the cellular effects of radiation and may provide significant neuroprotection from the effects of radiation-induced cognitive and behavioral skill deficits. Ninety-six C57BL/6 mice (48 pomegranate fed and 48 control were irradiated with proton radiation (2 Gy, and two-month postradiation behaviors were assessed using a battery of behavioral tests to measure cognitive and motor functions. Proton irradiation was associated with depression-like behaviors in the tail suspension test, but this effect was ameliorated by the pomegranate diet. Males, in general, displayed worse coordination and balance than females on the rotarod task, and the pomegranate diet ameliorated this effect. Overall, it appears that proton irradiation, which may be encountered in space, may induce a different pattern of behavioral deficits in males than females and that a pomegranate diet may confer protection against some of those effects.

  13. Pomegranate supplementation improves affective and motor behavior in mice after radiation exposure.

    Science.gov (United States)

    Dulcich, Melissa S; Hartman, Richard E

    2013-01-01

    Currently, NASA has plans for extended space travel, and previous research indicates that space radiation can have negative effects on cognitive skills as well as physical and mental health. With long-term space travel, astronauts will be exposed to greater radiation levels. Research shows that an antioxidant-enriched diet may offer some protection against the cellular effects of radiation and may provide significant neuroprotection from the effects of radiation-induced cognitive and behavioral skill deficits. Ninety-six C57BL/6 mice (48 pomegranate fed and 48 control) were irradiated with proton radiation (2 Gy), and two-month postradiation behaviors were assessed using a battery of behavioral tests to measure cognitive and motor functions. Proton irradiation was associated with depression-like behaviors in the tail suspension test, but this effect was ameliorated by the pomegranate diet. Males, in general, displayed worse coordination and balance than females on the rotarod task, and the pomegranate diet ameliorated this effect. Overall, it appears that proton irradiation, which may be encountered in space, may induce a different pattern of behavioral deficits in males than females and that a pomegranate diet may confer protection against some of those effects. PMID:23662154

  14. How radiation affects superbubbles : Through momentum injection in early phase and photo-heating thereafter

    Science.gov (United States)

    Gupta, Siddhartha; Nath, Biman B.; Sharma, Prateek; Shchekinov, Yuri

    2016-08-01

    Energetic winds and radiation from massive star clusters push the surrounding gas and blow superbubbles in the interstellar medium (ISM). Using 1-D hydrodynamic simulations, we study the role of radiation in the dynamics of superbubbles driven by a young star cluster of mass 106 M⊙. We have considered a realistic time evolution of the mechanical power as well as radiation power of the star cluster, and detailed heating and cooling processes. We find that the ratio of the radiation pressure on the shell (shocked ISM) to the thermal pressure (˜107 K) of the shocked wind region is almost independent of the ambient density, and it is greater than unity before ≲ 1 Myr. We explore the parameter space of density and dust opacity of the ambient medium, and find that the size of the hot gas (˜ 107 K) cavity is insensitive to the dust opacity (σd ≈ (0.1 - 1.5) × 10-21 cm2), but the structure of the photoionized (˜104 K) gas depends on it. Most of the radiative losses occur at ˜104 K, with sub-dominant losses at ≲ 103 K and ˜106 - 108 K. The superbubbles can retain as high as ˜10% of its input energy, for an ambient density of 103 mH cm-3. We discuss the role of ionization parameter and recombination-averaged density in understanding the dominant feedback mechanism. Finally, we compare our results with the observations of 30 Doradus.

  15. Does the radiation from the interim storage in Gorleben affect the sex ratio of newborn children?

    International Nuclear Information System (INIS)

    In the professional world but especially in public, the question is discussed whether ionizing radiation from nuclear facilities has a significant impact on the secondary sex ratio of newborn children in the vicinity of the plants. This issue is of exceptional importance in the region around Gorleben, where the opposition to nuclear facilities and activities for decades is particularly strong. At the site borders of the interim storage facility (TBL-G) of GNS the effective individual dose is about 0.2 mSv per year, mainly caused by neutron irradiation from 108 casks with high-level radioactive waste from reprocessing. In the surrounding villages there is no radiation measurable. Statistical studies allegedly have shown evidence that in some villages in the area and during certain periods, proportionately fewer girls were born in comparison to the average for the Federal Republic of Germany. Based on these purely statistical results henceforward was also alleged that neutron-induced secondary effects such as activation or secondary gamma radiation would be responsible for it. Monte Carlo calculations and special measurements yielded values of the dose at the plant border for activation products less than E-04 mSv/a and for secondary gamma radiation of about E-03 mSv/a. These results indicate that the ionizing radiation from the Gorleben interim storage facility cannot be held accountable for shifts of the secondary sex ratio.

  16. Sensitivity of APSIM/ORYZA model due to estimation errors in solar radiation

    OpenAIRE

    Alexandre Bryan Heinemann; Pepijn A.J. van Oort; Diogo Simões Fernandes; Aline de Holanda Nunes Maia

    2012-01-01

    Crop models are ideally suited to quantify existing climatic risks. However, they require historic climate data as input. While daily temperature and rainfall data are often available, the lack of observed solar radiation (Rs) data severely limits site-specific crop modelling. The objective of this study was to estimate Rs based on air temperature solar radiation models and to quantify the propagation of errors in simulated radiation on several APSIM/ORYZA crop model seasonal outputs, yield, ...

  17. Differences in the radiation sensitivity of human tooth enamel in an individual and among the individuals in dental ESR dosimetry

    International Nuclear Information System (INIS)

    To study the individual difference of radiation sensitivity of tooth enamel in dental ESR dosimetry, 144 enamel samples were separated from 5 subjects, irradiated with 60Co gamma-rays up to 1290x10-4 C/kg (500 R), and measured with the ESR system. The coefficient of variation of ESR signals obtained for all enamel samples except two samples from one tooth was 7.8%. (author)

  18. JNK inhibition sensitizes tumor cells to radiation-induced premature senescence via Bcl-2/ROS/DDR signaling pathway

    International Nuclear Information System (INIS)

    Premature senescence is considered as a cellular defense mechanism to prevent tumorigenesis. Although recent evidences demonstrate that c-Jun N-terminal kinase (JNK) is involved in the senescence process, the target and exact mechanism of JNK signaling in the regulation of cell proliferation has yet to be defined. In this study, we investigated the role of JNK in premature senescence and demonstrated JNK inhibition sensitized tumor cells to radiation-induced premature senescence

  19. Myocardial performance index is sensitive to changes in cardiac contractility, but is also affected by vascular load condition.

    Science.gov (United States)

    Uemura, Kazunori; Kawada, Toru; Zheng, Can; Li, Meihua; Shishido, Toshiaki; Sugimachi, Masaru

    2013-01-01

    Myocardial performance index (MPI), or Tei index, is measured by Doppler echocardiography in clinical practice. MPI has been shown to be useful in evaluating left ventricular (LV) performance and predicting prognosis in cardiac patients. However, the effects of LV load and contractile states on MPI remain to be thoroughly investigated. In 14 anesthetized dogs, we obtained LV pressure-volume relationship with use of sonomicrometry and catheter-tip manometry. MPI was determined from the time derivative of LV volume and pressure. LV end-systolic pressure-volume ratio (Ees'), effective arterial elastance (Ea) and LV end-diastolic volume (Ved) were used as indices of LV contractility, afterload and preload, respectively. Hemodynamic conditions were varied over wide ranges [heart rate (HR), 66-192 bpm; mean arterial pressure, 71-177 mmHg] by infusing cardiovascular agents, by inducing ischemic heart failure and by electrical atrial pacing. Multiple linear regression analysis of pooled data (66 data sets) indicated that MPI (0.6-1.8) significantly correlated with Ees' [1.5-17.5 mmHg · ml(-1), pVed (11-100 ml, p0.1). Theoretical analysis also indicated that MPI decreases following the increases in LV contractility and in preload, while it increases in response to an increase in LV afterload. We conclude that MPI sensitively detects changes in LV contractility. However, MPI is also affected by changes in LV afterload and preload. PMID:24109782

  20. Differences in the sensitivity of fungi and bacteria to season and invertebrates affect leaf litter decomposition in a Mediterranean stream.

    Science.gov (United States)

    Mora-Gómez, Juanita; Elosegi, Arturo; Duarte, Sofia; Cássio, Fernanda; Pascoal, Cláudia; Romaní, Anna M

    2016-08-01

    Microorganisms are key drivers of leaf litter decomposition; however, the mechanisms underlying the dynamics of different microbial groups are poorly understood. We investigated the effects of seasonal variation and invertebrates on fungal and bacterial dynamics, and on leaf litter decomposition. We followed the decomposition of Populus nigra litter in a Mediterranean stream through an annual cycle, using fine and coarse mesh bags. Irrespective of the season, microbial decomposition followed two stages. Initially, bacterial contribution to total microbial biomass was higher compared to later stages, and it was related to disaccharide and lignin degradation; in a later stage, bacteria were less important and were associated with hemicellulose and cellulose degradation, while fungi were related to lignin decomposition. The relevance of microbial groups in decomposition differed among seasons: fungi were more important in spring, whereas in summer, water quality changes seemed to favour bacteria and slowed down lignin and hemicellulose degradation. Invertebrates influenced litter-associated microbial assemblages (especially bacteria), stimulated enzyme efficiencies and reduced fungal biomass. We conclude that bacterial and fungal assemblages play distinctive roles in microbial decomposition and differ in their sensitivity to environmental changes, ultimately affecting litter decomposition, which might be particularly relevant in highly seasonal ecosystems, such as intermittent streams. PMID:27288197

  1. Characterization and application of radiation-sensitizing genes by DNA methylation in lung cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Il Lae; Kim, In Gyu; Kim, Kug Chan

    2011-03-15

    The sensitivity or resistance of cancer cells and normal tissues to ionizing radiation plays an important role in the clinical setting of lung cancer treatment. However, to date the exact molecular mechanisms of intrinsic radiosensitivity have not been well explained. In this study, we compared the radiosensitivity or radioresistance in two non-small cell lung cancers (NSCLCs), H460 and A549, and investigated the signaling pathways that confer radioresistance. H460 cells showed a significant G2/M arrest after 12 h of irradiation (5 Gy), reaching 60% of G2/M phase arrest. A549 cells also showed a significant G2/M arrest after 12 h of exposure; however, this arrest completely disappeared after 24 h of exposure. A549 has higher methylated CpG sites in PTEN, which is correlated with tumor radioresistance in some cancer cells, than H460 cells, and the average of the extent of the methylation was {approx}4.3 times higher in A549 cells than in H460 cells. As a result, PTEN expression was lower in A549 than in H460. Conducting Western blot analysis, we found that PTEN acted as a negative regulator for pAkt, and the pAkt acted as a negative regulator for p53 expression. According to the above results, we concluded that the radiosensitivity shown in H460 cells may be due to the higher expression of PTEN through p53 signaling pathway. The expression of the Wnt-antagonist Dickkopf gene (DKK) is downregulated in several types of tumors as a consequence of epigenetic DNA modification; four DKK members, DKK1, DKK2, DKK3, and DKK4, have been identified. In this study, we investigated another function of DKK3 in non-small cell lung cancer H460 cells, in which DKK3 was hypermethylated (44%) but still expressed, by interfering with DKK3 expression using DKK3-silencing RNA (SiRNA). We found that knockdown of DKK3 expression by DKK3 SiRNA transfection led to the detachment of H460 cells from the bottom of the culture plate and caused apoptosis. The expression of cyclindependent kinases

  2. Parameterization and sensitivity analyses of a radiative transfer model for remote sensing plant canopies

    Science.gov (United States)

    Hall, Carlton Raden

    A major objective of remote sensing is determination of biochemical and biophysical characteristics of plant canopies utilizing high spectral resolution sensors. Canopy reflectance signatures are dependent on absorption and scattering processes of the leaf, canopy properties, and the ground beneath the canopy. This research investigates, through field and laboratory data collection, and computer model parameterization and simulations, the relationships between leaf optical properties, canopy biophysical features, and the nadir viewed above-canopy reflectance signature. Emphasis is placed on parameterization and application of an existing irradiance radiative transfer model developed for aquatic systems. Data and model analyses provide knowledge on the relative importance of leaves and canopy biophysical features in estimating the diffuse absorption a(lambda,m-1), diffuse backscatter b(lambda,m-1), beam attenuation alpha(lambda,m-1), and beam to diffuse conversion c(lambda,m-1 ) coefficients of the two-flow irradiance model. Data sets include field and laboratory measurements from three plant species, live oak (Quercus virginiana), Brazilian pepper (Schinus terebinthifolius) and grapefruit (Citrus paradisi) sampled on Cape Canaveral Air Force Station and Kennedy Space Center Florida in March and April of 1997. Features measured were depth h (m), projected foliage coverage PFC, leaf area index LAI, and zenith leaf angle. Optical measurements, collected with a Spectron SE 590 high sensitivity narrow bandwidth spectrograph, included above canopy reflectance, internal canopy transmittance and reflectance and bottom reflectance. Leaf samples were returned to laboratory where optical and physical and chemical measurements of leaf thickness, leaf area, leaf moisture and pigment content were made. A new term, the leaf volume correction index LVCI was developed and demonstrated in support of model coefficient parameterization. The LVCI is based on angle adjusted leaf

  3. Real and limit sensitivity of some radiation detectors of THz/sub-THz ranges

    Directory of Open Access Journals (Sweden)

    Shevchik-Shekera A. V.

    2012-02-01

    Full Text Available It is shown that while calculating the NEP parameter of radiation detectors of THz/sub-THz range, the fluctuations of the background radiation flux at different temperatures of the background in the case of diffraction-limited beam should be taken into account.

  4. Factors and variables affecting tumor response to combined heat and radiation in head and neck

    International Nuclear Information System (INIS)

    The purpose of this report is to evaluate, retrospectively, the value of the combined modality over radiation alone with respect to CR rate and its correlation with some variables, such as tumor temperature and tumor volume, in a patient population homogeneous with respect to tumor site and histology and treated under the same conditions according to a treatment protocol. (orig./MG)

  5. How radiation affects superbubbles: Through momentum injection in early phase and photo-heating thereafter

    CERN Document Server

    Gupta, Siddhartha; Sharma, Prateek; Shchekinov, Yuri

    2016-01-01

    Energetic winds and radiation from massive star clusters push the surrounding gas and blow superbubbles in the interstellar medium (ISM). Using 1-D hydrodynamic simulations, we study the role of radiation in the dynamics of superbubbles driven by a young star cluster of mass $10^{6}$ M$_{\\odot}$. We have considered a realistic time evolution of the mechanical power as well as radiation power of the star cluster, and detailed heating and cooling processes. We find that the ratio of the radiation pressure on the shell (shocked ISM) to the thermal pressure ($\\sim10^{7}$ K) of the shocked wind region is almost independent of the ambient density, and it is greater than unity before $\\lesssim 1$ Myr. We explore the parameter space of density and dust opacity of the ambient medium, and find that the size of the hot gas ($\\sim$ 10$^{7}$ K) cavity is insensitive to the dust opacity ($\\sigma_{d}\\approx(0.1-1.5)\\times 10^{-21}$ cm$^{2}$), but the structure of the photoionized ($\\sim10^4$ K) gas depends on it. Most of th...

  6. UV radiation induced stress does not affect DMSP synthesis in the marine prymnesiophyte Emiliania huxleyi

    NARCIS (Netherlands)

    van Rijssel, M; Buma, A.G.J.

    2002-01-01

    A possible coupling between UV radiation (UVR; 280 to 400 nm) induced stress and the production of dimethylsulfoniopropionate (DMSP), the precursor of the climate-regulating gas dimethylsulfide (DMS), was investigated in the marine prymnesiophyte Emiliania huxleyi. To this end, axenic cultures of E.

  7. Comparison of heat and radiation sensitivity in normal C3H-10T1/2 cells and cells transformed by radiation or the H ras oncogene

    International Nuclear Information System (INIS)

    C/sub 3/H 10T1/2 cells were transformed from the normal to the malignant state using X-rays or by transfection with a plasmid containing the active H ras oncogene. Clones of cells with a transformed morphology were isolated and grown into large populations. These cells were tested and produced tumors in C/sub 3/H mice. Seven clones transformed by radiation showed a range of sensitivity to heat and X-rays that varied from greater to lesser than the heat and X-ray sensitivity in normal cells. Similar results were observed for the cells transformed by the H ras oncogene. Thus, the malignant transformation of C/sub 3/H 10T1/2 cells by X-rays or H ras oncogenes did not, in general result in increased thermal sensitivity, implying that the malignant phenotype is not intrinsically more heat sensitive than the normal cell. The thermal sensitivity in the various transformed cell lines was not correlated with membrane cholesterol or phospholipid content

  8. Increased effect of hypoxic cell radiation sensitizers in combination with BSO, a substance depleting the intracellular radioprotective thiols

    International Nuclear Information System (INIS)

    The radiosensitizing effect of misonidazole, an electron affinic nitroimidazole, and BSO (DL-buthionine-S, R-sulfoximine), an inhibitor of glutathione synthesis, was tested alone, or in combination. The yield of single-strand DNA breaks in hypoxically exposed cells, expressing mainly the end-effect of radiochemical processes, was used as the measure of sensitivity. At equimolar concentrations, misonidazole appeared to have a greater sensitizing action than BSO. When used in combination, the effect of the two substances was additive. The data were interpreted to support the concept of a competition mechanism, misonidazole fixing radiation damaged, key target molecules in a competition with cellular glutathione which may repair radical lesions. The results indicate that misonidazole, in a combination with BSO, can sensitize hypoxic tumor cells efficiently even at low concentrations. In the clinics, such a combined treatment would permit a practice to circumvent the limitations posed by the neurotoxicity of misonidazole. (author)

  9. Combined radiation-protective and radiation-sensitizing agents. III. Radiosensitization by misonidazole as a function of concentrations of endogenous glutathione or exogenous thiols

    International Nuclear Information System (INIS)

    Radiosensitization of V79 Chinese hamster fibroblasts by 0.5 mM misonidazole is a smooth function of endogenous glutathione (GSH) levels as modulated upwards by pre-incubation in medium containing cysteamine, or downwards by pre-incubation in medium containing buthionine sulfoximine. The enhancement ratio (radiation sensitivity in nitrogen/radiation sensitivity in nitrogen +/- sensitizer or thiol) varies from 1.3 at 12 mM to 2.25 at less than 0.1 mM endogenous GSH. The enhanced radiosensitivity of thiol-depleted hypoxic cells is reversed when exogenous thiols are added, and for equivalent ER, the exogenous thiol concentrations are much lower than the endogenous GSH concentrations. Measurement of intracellular drug concentrations amplified rather than diminished the above discrepancy, since intracellular concentrations of cysteamine were lower and glutathione much lower than the extracellular concentrations. Three possible explanations are addressed: an external membrane component of damage is involved, long-range protection to DNA target radicals is possible from outside the cell (e.g., donation of electrons), and (c) endogenous glutathione is not in a free or exchangeable state (e.g., bound)

  10. Tropical Convective Responses to Microphysical and Radiative Processes: A Sensitivity Study With a 2D Cloud Resolving Model

    Science.gov (United States)

    Li, Xiao-Fan; Sui, C.-H.; Lau, K.-M.; Tao, W.-K.

    2004-01-01

    Prognostic cloud schemes are increasingly used in weather and climate models in order to better treat cloud-radiation processes. Simplifications are often made in such schemes for computational efficiency, like the scheme being used in the National Centers for Environment Prediction models that excludes some microphysical processes and precipitation-radiation interaction. In this study, sensitivity tests with a 2D cloud resolving model are carried out to examine effects of the excluded microphysical processes and precipitation-radiation interaction on tropical thermodynamics and cloud properties. The model is integrated for 10 days with the imposed vertical velocity derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. The experiment excluding the depositional growth of snow from cloud ice shows anomalous growth of cloud ice and more than 20% increase of fractional cloud cover, indicating that the lack of the depositional snow growth causes unrealistically large mixing ratio of cloud ice. The experiment excluding the precipitation-radiation interaction displays a significant cooling and drying bias. The analysis of heat and moisture budgets shows that the simulation without the interaction produces more stable upper troposphere and more unstable mid and lower troposphere than does the simulation with the interaction. Thus, the suppressed growth of ice clouds in upper troposphere and stronger radiative cooling in mid and lower troposphere are responsible for the cooling bias, and less evaporation of rain associated with the large-scale subsidence induces the drying in mid and lower troposphere.

  11. Factors Affecting the Medical Management and Care of Persons Accidentally Overexposed to Ionising Radiations

    International Nuclear Information System (INIS)

    All establishments where acute external radiation overexposure or significant intake of radioactive materials may occur have to make plans to deal with such situations. This paper describes the various stages in such plans and covers selection, early care and, where necessary, transfer of exposed persons for more specialised care. The factors influencing decisions on these matters are discussed, and the necessary degrees of urgency and precision at various stages of the process are reviewed. All emergency schemes have the objective of guarding against deterioration in the condition of the patient and of preparing him for further definitive treatment. In this respect, the approach to cases of internal contamination is different from that applicable to extemal radiation cases. These differences are reviewed and an outline emergency drill is described for each category of incident. Occupational radiation incidents can be considered as a specialised aspect of occupational health but the planning attention devoted to them has been more detailed than that thought appropriate in other fields of industrial hygiene and safety. The need for a clear distinction in the approach to procedures carried out for the benefit of the patient and those carried out for radiological reasons or research purposes is discussed. (author)

  12. Rate and duration of seed filling and yield of soybean affected by water and radiation deficits

    Directory of Open Access Journals (Sweden)

    Kazem GHASSEMI-GOLEZANI

    2015-11-01

    Full Text Available Seed filling and yield of soybean under water and radiation deficits were investigated during 2011 and 2012. Treatments were irrigations (I1, I2, I3 and I4 for irrigation after 60, 90, 120 and 150 mm evaporation from class A pan, respectively in main plots and light interceptions (L1: 100 %, L2: 65 % and L3: 25 % sunlight in sub-plots. Seeds per plant under I1 and I2 decreased, but under I3 and I4 increasedas a result of radiation deficit. Maximum seed weight and seed filling duration of plants under 25 % light interception (L3 were higher than those under full sunlight (L1 and 65 % light interception (L2. In contrast, plants under full sunlight had the highest seed filling rate, particularly under water stress. Seed filling duration under severe light deficit (L3 was about 9 days longer than that under full sunlight (L1, leading to 15.8 % enhancement in maximum seed weight. Decreasing seed yield of soybean under well watering and mild water stress and improving it under moderate and severe water deficit due to low solar radiation are directly related with changes in seed filling duration and consequently in seed weight and number of seeds per plant under these conditions.

  13. Factors Affecting Radiation Exposure during Lumbar Epidural Steroid Injection: A Prospective Study in 759 Patients

    Science.gov (United States)

    Kim, Suyoung; Shin, Joon-Ho; Lee, Joon Woo; Kang, Heung Sik; Lee, Guen Young

    2016-01-01

    Objective To estimate and compare radiation exposure and intervention time during lumbar epidural steroid injection (ESI) 1) under different practitioners and methods with continuous fluoroscopic monitoring, and 2) under one practitioner with different methods and monitoring. Materials and Methods We consecutively recruited 804 patients who underwent lumbar ESI and 759 patients who underwent 922 interventions were included for analysis in this investigation. Three different practitioners (a senior faculty member, junior faculty member, trainee) performed lumbar ESI using different methods (caudal, interlaminar, transforaminal). The senior faculty member performed lumbar ESI under two different methods of fluoroscopic monitoring (continuous [CM] and intermittent monitoring [IM]). The dose area product (DAP) fluoroscopy time, and intervention time during lumbar ESI were compared for 1) ESI methods and practitioners under CM, and 2) ESI methods and monitoring. Results With CM, interaction between the effects of the practitioner and the intervention on DAP was significant (p fluoroscopy time (p = 0.672) or intervention time (p = 0.852). The significant main effects included the practitioner and intervention on DAP, fluoroscopy time, and intervention time with CM (p fluoroscopy time for caudal, interlaminar, and transforaminal ESI were higher with CM than with IM (p < 0.001). Intervention time did not differ between CM and IM. Conclusion Radiation exposure is dependent on the practitioners and methods and within the established safety limits during lumbar ESIs under CM. With an experienced practitioner, IM leads to less radiation exposure than CM. PMID:27134528

  14. Low-power millimeter wave radiations do not alter stress-sensitive gene expression of chaperone proteins.

    Science.gov (United States)

    Zhadobov, M; Sauleau, R; Le Coq, L; Debure, L; Thouroude, D; Michel, D; Le Dréan, Y

    2007-04-01

    This article reports experimental results on the influence of low-power millimeter wave (MMW) radiation at 60 GHz on a set of stress-sensitive gene expression of molecular chaperones, namely clusterin (CLU) and HSP70, in a human brain cell line. Selection of the exposure frequency is determined by its near-future applications for the new broadband civil wireless communication systems including wireless local area networks (WLAN) for domestic and professional uses. Frequencies around 60 GHz are strongly attenuated in the earth's atmosphere and such radiations represent a new environmental factor. An exposure system operating in V-band (50-75 GHz) was developed for cell exposure. U-251 MG glial cell line was sham-exposed or exposed to MMW radiation for different durations (1-33 h) and two different power densities (5.4 microW/cm(2) or 0.54 mW/cm(2)). As gene expression is a multiple-step process, we analyzed chaperone proteins induction at different levels. First, using luciferase reporter gene, we investigated potential effect of MMWs on the activation of transcription factors (TFs) and gene promoter activity. Next, using RT-PCR and Western blot assays, we verified whether MMW exposure could alter RNA accumulation, translation, or protein stability. Experimental data demonstrated the absence of significant modifications in gene transcription, mRNA, and protein amount for the considered stress-sensitive genes for the exposure durations and power densities investigated. The main results of this study suggest that low-power 60 GHz radiation does not modify stress-sensitive gene expression of chaperone proteins. PMID:17080454

  15. Sensitivity of surface radiation budget to clouds over the Asian monsoon region

    Indian Academy of Sciences (India)

    S Balachandran; M Rajeevan

    2007-04-01

    Using the ISCCP–FD surface radiative flux data for the summer season (June to September) of the period 1992 to 1995, an analysis was done to understand the role of clouds on the surface radiation budget over the Asian monsoon region. At the top of atmosphere (TOA) of convective regions of the Asian monsoon region, the short wave radiative forcing (SWCRF) and long wave radiative forcing (LWCRF) do not cancel each other resulting in occurrence of the net cloud radiative forcing values exceeding −30W/m2. This type of imbalance between SWCRF and LWCRF at TOA is reflected down on the earth surface–atmosphere system also as an imbalance between surface netcloud radiative forcing (NETCRF) and atmospheric NETCRF. Based on the regression analysis of the cloud effects on the surface radiation budget quantities, it has been observed that generally, the variance explained by multiple type cloud data is 50% more than that of total cloud cover alone. In case of SWCRF, the total cloud cover can explain about 3% (7%) of the variance whereas the three cloud type descriptions of clouds can explain about 44% (42%) of the variance over oceanic (land) regions. This highlights the importance of cloud type information in explaining the variations of surface radiation budget. It has been observed that the clouds produce more cooling effect in short-wave band than the warming effect in long-wave band resulting in a net cooling at the surface. Over the oceanic region, variations in high cloud amount contribute more to variations in SWCRF while over land regions both middle and high cloud variations make substantial contributions to the variations in both SWCRF and NETCRF.

  16. Estimation of mineral dust longwave radiative forcing: sensitivity study to particle properties and application to real cases over Barcelona

    Directory of Open Access Journals (Sweden)

    M. Sicard

    2014-03-01

    Full Text Available The aerosol radiative effect in the longwave (LW spectral range is sometimes not taken into account in atmospheric aerosol forcing studies at local scale because the LW aerosol effect is assumed to be negligible. At regional and global scale this effect is partially taken into account: aerosol absorption is taken into account but scattering is still neglected. However, aerosols with strong absorbing and scattering properties in the LW region, like mineral dust, can have a non-negligible radiative effect in the LW spectral range (both at surface and top of the atmosphere which can counteract their cooling effect occurring in the shortwave spectral range. The first objective of this research is to perform a sensitivity study of mineral dust LW radiative forcing (RF as a function of dust microphysical and optical properties using an accurate radiative transfer model which can compute vertically-resolved shortwave and longwave aerosol RF. Radiative forcing simulations in the LW range have shown an important sensitivity to the following parameters: aerosol load, radius of the coarse mode, refractive index, aerosol vertical distribution, surface temperature and surface albedo. The scattering effect has been estimated to contribute to the LW RF up to 18% at the surface and up to 38% at the top of the atmosphere. The second objective is the estimation of the shortwave and longwave dust RF for 11 dust outbreaks observed in Barcelona. At the surface, the LW RF varies between +2.8 and +10.2 W m−2, which represents between 11 and 26% (with opposite sign of the SW component, while at the top of the atmosphere the LW RF varies between +0.6 and +5.8 W m−2, which represents between 6 and 26% (with opposite sign of the SW component.

  17. Impact of radiation therapy for benign diseases; Role de la radiotherapie dans les affections benignes

    Energy Technology Data Exchange (ETDEWEB)

    Kantor, G. [Institut National de la Sante et de la Recherche Medicale (INSERM), Fondation Bergonie, 33 - Bordeaux (France); Van Houtte, P.; Beauvois, S.; Roelandts, M. [Institut Bordet, Brussels (Belgium)

    1997-12-31

    Radiation therapy of benign diseases represent a wide panel of indications. Some indications are clearly identified as treatment of arteriovenous malformations (AVM), hyperthyroid ophthalmopathy, postoperative heterotopic bone formations or keloid scars. Some indications are under evaluation as complications induced by neo-vessels of age-related macular degeneration or coronary restenosis after angioplasty. Some indications remain controversial with poor evidence of efficiency as treatment of bursitis, tendinitis or Dupuytren`s disease. Some indications are now obsolete such as warts, or contra-indicated as treatment of infant and children. (authors)

  18. Studies of variation in inherent sensitivities to radiation, 5-fluorouracil and methotrexate in a series of human and murine tumor cell lines in vitro

    International Nuclear Information System (INIS)

    Clinical studies have reported reduced response rates to subsequent chemotherapy in certain tumors recurring after radiotherapy. These authors have investigated whether there are any correlations between radiation and drug responses in vitro using a range of murine and human tumor cell lines. They have compared sensitivities to X-irradiation and to 24 hr exposures to two widely used antitumor drugs, methotrexate and 5-fluorouracil. The 4 murine lines selected showed a range of radiation responses with Do values of 0.48-0.76 Gy. Methotrexate sensitivities also exhibited an 800-fold difference which appeared to correlate inversely with radiation response. Sensitivity to 5-FU was less variable in these cells and was unrelated to radiation response. In contrast, in the human lines tested, no correlations were observed between drug sensitivities and radiation response. The six lines tested showed a range of radiation responses with Do values of 0.66-1.59 Gy. Methotrexate sensitivities ranged only over a 150-fold concentration but, contrasting with data from the murine cells, no correlation with radiation response was apparent. Similarly, no correlations between response to 5-fluorouracil and radiation or 5-fluorouracil and methotrexate were noted, which is inconsistent with results using murine cells

  19. DNA conformation of Chinese hamster V79 cells and sensitivity to ionizing radiation

    International Nuclear Information System (INIS)

    Chinese hamster V79 cells grown for 20 h in suspension culture form small clusters of cells (spheroids) which are more resistant to killing by ionizing radiation than V79 cells grown as monolayers. This resistance appears to be due to the greater capacity of cells grown in contact to repair radiation damage. Attempts to relate this ''contact effect'' to differences in DNA susceptibility or DNA repair capacity have provided conflicting results. Two techniques, alkaline sucrose gradient sedimentation and alkaline elution, show no difference in the amounts of radiation-induced DNA single-strand breakage or its repair between suspension or monolayer cells. However, using the alkali-unwinding assay, the rate of DNA unwinding is much slower for suspension cells than for monolayer cells. Interestingly, a decrease in salt concentration or in pH of the unwinding solution eliminates these differences in DNA unwinding kinetics. A fourth assay, sedimentation of nucleoids on neutral sucrose gradients, also shows a significant decrease in radiation damage produced in suspension compared to monolayer cultures. It is believed that this assay measures differences in DNA conformation (supercoiling) as well as differences in DNA strand breakage. We conclude from these four assays that the same number of DNA strand breaks/Gy is produced in monolayer and spheroid cells. However, changes in DNA conformation or packaging occur when cells are grown as spheroids, and these changes are responsible for reducing DNA damage by ionizing radiation

  20. Physiological sensitivity of plants along an elevational gradient to UV-B radiation

    International Nuclear Information System (INIS)

    Seeds from four plant pairs collected from contrasting elevations in Hawaii were grown in greenhouses at the University of Maryland at UV-B radiation levels that approximated a 20% and 40% stratospheric ozone depletion anticipated at sea level in Maui. In general, increases in UV-B radiation resulted in earlier reproductive effort, increased dark respiration and maintenance of relative water content (RWC), photosynthesis, and apparent quantum efficiency (AQE) in plants from higher elevations where natural UV-B radiation is already high. In contrast, plants collected from low elevational ranges showed a significant decline in average plant and floral dry biomass, a decline in AQE and RWC, and a reduction in light-saturated photosynthetic capacity. Increases in UV-B-absorbing compounds (e.g., flavonoids), were noted for low elevation but not high elevation plants. However, plants from high elevations produced a consistently larger amount of these compounds even in the absence of UV-B radiation. This study suggests that plants growing in a naturally high UV-B environment may have developed or maintained mechanisms related to reproductive phenology and carbon uptake which may maintain productivity in a high UV-B environment. This would also suggest that ecotypic differentiation may have occurred in response to increasing UV-B radiation over an elevational gradient. The range of adaptability to increased UV-B also implies changes in species and community dynamics that might be anticipated in natural plant populations if stratospheric ozone depletion continues

  1. Biodistribution and radiation dosimetry of [N-methyl-11C]mirtazapine, an antidepressant affecting adrenoceptors

    International Nuclear Information System (INIS)

    Central adrenoceptors cannot currently be studied by PET neuroimaging due to a lack of appropriate radioligands. The fast-acting antidepressant drug mirtazapine, radiolabelled for PET, may be of value for assessing central adrenoceptors, provided that the radiation dosimetry of the radioligand is acceptable. To obtain that information, serial whole-body images were made for up to 70 min following intravenous injection of 326 and 185 MBq [N-methyl-11C]mirtazapine (specific activities E.O.S. of 119 and 39 GBq/μmol, respectively) in a healthy volunteer. Ten source organs plus remaining body were considered in estimating absorbed radiation doses calculated using MIRD 3.1. The highest absorbed organ doses were found to the lungs (3.4x10-2 mGy/MBq), adrenals (1.2x10-2 mGy/MBq), spleen (1.2x10-2 mGy/MBq), and gallbladder wall (1.1x10-2 mGy/MBq). The effective dose was estimated to be 6.8x10-3 mSv/MBq, which is similar to that produced by several radioligands used routinely for neuroimaging

  2. Comparison of the Sensitivity of Surface Downward Longwave Radiation to Changes in Water Vapor at Two High Elevation Sites

    Science.gov (United States)

    Chen, Yonghua; Naud, Catherine M.; Rangwala, Imtiaz; Landry, Christopher C.; Miller, James R.

    2014-01-01

    Among the potential reasons for enhanced warming rates in many high elevation regions is the nonlinear relationship between surface downward longwave radiation (DLR) and specific humidity (q). In this study we use ground-based observations at two neighboring high elevation sites in Southwestern Colorado that have different local topography and are 1.3 kilometers apart horizontally and 348 meters vertically. We examine the spatial consistency of the sensitivities (partial derivatives) of DLR with respect to changes in q, and the sensitivities are obtained from the Jacobian matrix of a neural network analysis. Although the relationship between DLR and q is the same at both sites, the sensitivities are higher when q is smaller, which occurs more frequently at the higher elevation site. There is a distinct hourly distribution in the sensitivities at both sites especially for high sensitivity cases, although the range is greater at the lower elevation site. The hourly distribution of the sensitivities relates to that of q. Under clear skies during daytime, q is similar between the two sites, however under cloudy skies or at night, it is not. This means that the DLR-q sensitivities are similar at the two sites during daytime but not at night, and care must be exercised when using data from one site to infer the impact of water vapor feedbacks at another site, particularly at night. Our analysis suggests that care should be exercised when using the lapse rate adjustment to infill high frequency data in a complex topographical region, particularly when one of the stations is subject to cold air pooling as found here.

  3. Comparison of the sensitivity of surface downward longwave radiation to changes in water vapor at two high elevation sites

    International Nuclear Information System (INIS)

    Among the potential reasons for enhanced warming rates in many high elevation regions is the nonlinear relationship between surface downward longwave radiation (DLR) and specific humidity (q). In this study we use ground-based observations at two neighboring high elevation sites in Southwestern Colorado that have different local topography and are 1.3 km apart horizontally and 348 m vertically. We examine the spatial consistency of the sensitivities (partial derivatives) of DLR with respect to changes in q, and the sensitivities are obtained from the Jacobian matrix of a neural network analysis. Although the relationship between DLR and q is the same at both sites, the sensitivities are higher when q is smaller, which occurs more frequently at the higher elevation site. There is a distinct hourly distribution in the sensitivities at both sites especially for high sensitivity cases, although the range is greater at the lower elevation site. The hourly distribution of the sensitivities relates to that of q. Under clear skies during daytime, q is similar between the two sites, however under cloudy skies or at night, it is not. This means that the DLR–q sensitivities are similar at the two sites during daytime but not at night, and care must be exercised when using data from one site to infer the impact of water vapor feedbacks at another site, particularly at night. Our analysis suggests that care should be exercised when using the lapse rate adjustment to infill high frequency data in a complex topographical region, particularly when one of the stations is subject to cold air pooling as found here. (letter)

  4. Sensitivity of modelled sulfate radiative forcing to DMS concentration and air-sea flux formulation

    Science.gov (United States)

    Tesdal, J.-E.; Christian, J. R.; Monahan, A. H.; von Salzen, K.

    2015-09-01

    In this study, we use an atmospheric general circulation model with explicit aerosol chemistry (CanAM4.1) and several climatologies of surface ocean DMS concentration to assess uncertainties about the climate impact of ocean DMS efflux. Despite substantial variation in the spatial pattern and seasonal evolution of simulated DMS fluxes, the global mean radiative forcing is approximately linearly proportional to the global mean surface flux of DMS; the spatial and temporal distribution of ocean DMS efflux has only a minor effect on the global radiation balance. The effect of the spatial structure, however, generates statistically significant changes in the global mean concentrations of some aerosol species. The effect of seasonality on net radiative forcing is larger than that of spatial distribution, and is significant at global scale.

  5. Down-regulation of ATM Protein Sensitizes Human Prostate Cancer Cells to Radiation-induced Apoptosis*

    OpenAIRE

    Truman, Jean-Philip; Gueven, Nuri; Lavin, Martin; Leibel, Steven; Kolesnick, Richard; Fuks, Zvi; Haimovitz-Friedman, Adriana

    2005-01-01

    Treatment with the protein kinase C activator 12-O tetradecanoylphorbol 12-acetate (TPA) enables radiation-resistant LNCaP human prostate cancer cells to undergo radiation-induced apoptosis, mediated via activation of the enzyme ceramide synthase (CS) and de novo synthesis of the sphingolipid ceramide (Garzotto, M., Haimovitz-Friedman, A., Liao, W. C., White-Jones, M., Huryk, R., Heston, D. W. W., Cardon-Cardo, C., Kolesnick, R., and Fuks, Z. (1999) Cancer Res. 59, 5194-5201). Here, we show t...

  6. Grafting of thermo-sensitive N-vinylcaprolactam onto silicone rubber through the direct radiation method

    Science.gov (United States)

    Valencia-Mora, Ricardo A.; Zavala-Lagunes, Edgar; Bucio, Emilio

    2016-07-01

    The modification of silicone rubber films (SR) was performed by radiation-induced graft polymerization of thermosensitive poly(N-vinylcaprolactam) (PNVCL) using gamma rays from a Co-60 source. The graft polymerization was obtained by a direct radiation method with doses from 5 to 70 kGy, at monomer concentrations between 5% and 70% in toluene. Grafting was confirmed by infrared, differential scanning calorimetry, thermogravimetric analysis, and swelling studies. The lower critical solution temperature (LCST) of the grafted SR was measured by swelling and differential scanning calorimetry.

  7. Identification of a radiation sensitivity gene expression profile in primary fibroblasts derived from patients who developed radiotherapy-induced fibrosis

    International Nuclear Information System (INIS)

    Background and purpose: During radiotherapy, normal tissue is unavoidably exposed to radiation which results in severe normal tissue reactions in a small fraction of patients. Because those who are sensitive cannot be determined prior to radiotherapy, the doses are limited to all patients to avoid an unacceptable number of severe adverse normal tissue responses. This limitation restricts the optimal treatment for individuals who are more tolerant to radiation. Genetic variation is a likely source for the normal tissue radiosensitivity variation observed between individuals. Therefore, understanding the radiation response at the genomic level may provide knowledge to develop individualized treatment and improve radiotherapy outcomes. Material and methods: Exon arrays were utilized to compare the basal expression profile between cell lines derived from six cancer patients with and without severe fibrosis. These data were supported by qRT-PCR and RNA-Seq techniques. Results: A set of genes (FBN2, FST, GPRC5B, NOTCH3, PLCB1, DPT, DDIT4L and SGCG) were identified as potential predictors for radiation-induced fibrosis. Many of these genes are associated with TGFβ or retinoic acid both having known links to fibrosis. Conclusion: A combinatorial gene expression approach provides a promising strategy to predict fibrosis in cancer patients prior to radiotherapy

  8. Variation of radiation-sensitivity of neural stem and progenitor cell populations within the developing mouse brain

    International Nuclear Information System (INIS)

    We investigated the DNA damage response (DDR) of fetal neural stem and progenitor cells (NSPC), since exposure to ionizing radiation can severely impair the brain development. We compared apoptosis induction in the dorsal tel-encephalon and the lateral ganglionic eminences (LGE) of mouse embryos after an in utero irradiation. We used two thymidine analogs, together with the physical position of nuclei within brain structures, to determine the fate of irradiated NSPC. NSPC did not activate an apparent protein 21(p21)- dependent G1/S checkpoint within the LGE as their counterparts within the dorsal tel-encephalon. However, the levels of radiation induced apoptosis differed between the two tel-encephalic regions, due to the high radiation sensitivity of intermediate progenitors of the LGE. Besides radial glial cells, that function as neural stem cells, were more resistant and were reoriented toward self-renewing within hours following irradiation. The lack of the p21-dependent-cell cycle arrest at the G1/S transition appears to be a general feature of NSPC in the developing brain. However, we found variation of radiation response in function of the types of NSPC. Factors involved in DDR and those involved in the regulation of neurogenesis are intricately linked in determining the cell fate after irradiations. (authors)

  9. Dose escalation with three-dimensional conformal radiation therapy affects the outcome in prostate cancer

    International Nuclear Information System (INIS)

    Purpose: Three-dimensional conformal radiation therapy (3D-CRT) is a technique designed to deliver prescribed radiation doses to localized tumors with high precision, while effectively excluding the surrounding normal tissues. It facilitates tumor dose escalation which should overcome the relative resistance of tumor clonogens to conventional radiation dose levels. The present study was undertaken to test this hypothesis in patients with clinically localized prostate cancer. Methods and Materials: A total of 743 patients with clinically localized prostate cancer were treated with 3D-CRT. As part of a phase I study, the tumor target dose was increased from 64.8 to 81 Gy in increments of 5.4 Gy. Tumor response was evaluated by post-treatment decrease of serum prostate-specific antigen (PSA) to levels of ≤1.0 ng/ml and by sextant prostate biopsies performed ≥2.5 years after completion of 3D-CRT. PSA relapse-free survival was used to evaluate long-term outcome. The median follow-up was 3 years (range: 1-7.6 years). Results: Induction of an initial clinical response was dose-dependent, with 90% of patients receiving 75.6 or 81.0 Gy achieving a PSA nadir ≤1.0 ng compared with 76% and 56% for those treated with 70.2 Gy and 64.8 Gy, respectively (p < 0.001). The 5-year actuarial PSA relapse-free survival for patients with favorable prognostic indicators (stage T1-2, pretreatment PSA ≤10.0 ng/ml and Gleason score ≤6) was 85%, compared to 65% for those with intermediate prognosis (one of the prognostic indicators with a higher value) and 35% for the group with unfavorable prognosis (two or more indicators with higher values) (p < 0.001). PSA relapse-free survival was significantly improved in patients with intermediate and unfavorable prognosis receiving ≥75.6 Gy (p < 0.05). A positive biopsy at ≥2.5 years after 3D-CRT was observed in only 1/15 (7%) of patients receiving 81.0 Gy, compared with 12/25 (48%) after 75.6 Gy, 19/42 (45%) after 70.2 Gy, and 13/23 (57

  10. Quasi-analytical solutions of hybrid platform and the optimization of highly sensitive thin-film sensors for terahertz radiation

    CERN Document Server

    Tapsanit, Piyawath; Ishihara, Teruya; Otani, Chiko

    2016-01-01

    We present quasi-analytical solutions (QANS) of hybrid platform (HP) comprising metallic grating (MG) and stacked-dielectric layers for terahertz (THz) radiation. The QANS are validated by finite difference time domain simulation. It is found that the Wood anomalies induce the high-order spoof surface plasmon resonances in the HP. The QANS are applied to optimize new perfect absorber for THz sensing of large-area thin film with ultrahigh figure of merit reaching fifth order of magnitude for the film thickness 0.0001p (p: MG period). The first-order Wood's anomaly of the insulator layer and the Fabry-Perot in the slit's cavity account for the resonance of the perfect absorber. The QANS and the new perfect absorber may lead to highly sensitive and practical nano-film refractive index sensor for THz radiation.

  11. Radiation

    International Nuclear Information System (INIS)

    The chapter one presents the composition of matter and atomic theory; matter structure; transitions; origin of radiation; radioactivity; nuclear radiation; interactions in decay processes; radiation produced by the interaction of radiation with matter

  12. Correction of glutathione metabolism in the liver of albino rats affected by low radiation doses

    International Nuclear Information System (INIS)

    The levels of total glutathione GSH, GSSG and the activities of glutathione reductase and glutathione peroxidase were studied in the liver of adult albino rats subjected to 3-fold external γ-irradiation throughout 2 weeks at the overall dose of 0.75 Gy after 15 h, 2 and 5 days from the last irradiation. Some animals were injected intraperitoneally with the pantothenate containing complex > 3 times on days 1-3 before the irradiation. The radiation related decrease of GSH, GSH/GSSG and the total glutathione level was prevented by the prophylactic administration of the complex and probably at the expense of the activation of the G-SH biosynthesis and/or transport in the liver by the CoA biosynthetic precursor. (author)

  13. Prognostic factors affecting local control of hepatic tumors treated by stereotactic body radiation therapy

    International Nuclear Information System (INIS)

    Robotic Stereotactic Body Radiation Therapy with real-time tumor tracking has shown encouraging results for hepatic tumors with good efficacy and low toxicity. We studied the factors associated with local control of primary or secondary hepatic lesions post-SBRT. Since 2007, 153 stereotactic liver treatments were administered to 120 patients using the CyberKnife® System. Ninety-nine liver metastases (72 patients), 48 hepatocellular carcinomas (42 patients), and six cholangiocarcinomas were treated. On average, three to four sessions were delivered over 12 days. Twenty-seven to 45 Gy was prescribed to the 80% isodose line. Margins consisted of 5 to 10 mm for clinical target volume (CTV) and 3 mm for planning target volume (PTV). Median size was 33 mm (range, 5–112 mm). Median gross tumor volume (GTV) was 32.38 cm3 (range, 0.2–499.5 cm3). Median total dose was 45 Gy in three fractions. Median minimum dose was 27 Gy in three fractions. With a median follow-up of 15.0 months, local control rates at one and two years were 84% and 74.6%, respectively. The factors associated with better local control were lesion size < 50 mm (p = 0.019), GTV volume (p < 0.05), PTV volume (p < 0.01) and two treatment factors: a total dose of 45 Gy and a dose–per-fraction of 15 Gy (p = 0.019). Dose, tumor diameter and volume are prognostic factors for local control when a stereotactic radiation therapy for hepatic lesions is considered. These results should be considered in order to obtain a maximum therapeutic efficacy

  14. WE-E-BRE-03: Biological Validation of a Novel High-Throughput Irradiator for Predictive Radiation Sensitivity Bioassays

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, TL; Martin, JA; Shepard, AJ; Bailey, AM; Nickel, KP; Kimple, RJ; Bednarz, BP [University of Wisconsin, Madison, WI (United States)

    2014-06-15

    Purpose: The large dose-response variation in both tumor and normal cells between individual patients has led to the recent implementation of predictive bioassays of patient-specific radiation sensitivity in order to personalize radiation therapy. This exciting new clinical paradigm has led us to develop a novel high-throughput, variable dose-rate irradiator to accompany these efforts. Here we present the biological validation of this irradiator through the use of human cells as a relative dosimeter assessed by two metrics, DNA double-strand break repair pathway modulation and intercellular reactive oxygen species production. Methods: Immortalized human tonsilar epithelial cells were cultured in 96-well micro titer plates and irradiated in groups of eight wells to absorbed doses of 0, 0.5, 1, 2, 4, and 8 Gy. High-throughput immunofluorescent microscopy was used to detect γH2AX, a DNA double-strand break repair mechanism recruiter. The same analysis was performed with the cells stained with CM-H2DCFDA that produces a fluorescent adduct when exposed to reactive oxygen species during the irradiation cycle. Results: Irradiations of the immortalized human tonsilar epithelial cells at absorbed doses of 0, 0.5, 1, 2, 4, and 8 Gy produced excellent linearity in γH2AX and CM-H2DCFDA with R2 values of 0.9939 and 0.9595 respectively. Single cell gel electrophoresis experimentation for the detection of physical DNA double-strand breaks in ongoing. Conclusions: This work indicates significant potential for our high-throughput variable dose rate irradiator for patient-specific predictive radiation sensitivity bioassays. This irradiator provides a powerful tool by increasing the efficiency and number of assay techniques available to help personalize radiation therapy.

  15. SiRNA-mediated IGF-1R inhibition sensitizes human colon cancer SW480 cells to radiation

    International Nuclear Information System (INIS)

    Purpose. Insulin like growth factor receptor 1 (IGF-1R) is well-documented to play a key role in radiation response and tumor radiosensitivity, thus offering an attractive clinic drug target to enhance tumor sensitivity to anti-cancer radiotherapy. Material and methods. Human colon carcinoma SW480 cells were transfected with the specific small interference RNA (siRNA) expression vector (pkD-shRNA-IGF-1R-V2) designed to target IGF-1R mRNA. The expression of IGF-1R mRNA and its protein among the transfected and untransfected cells were detected by semi-quantitative RT-PCR and ELISA assay. The changes in cell radiosensitivity were examined by MTT assay. Results. Transfection of mammalian expression vector pkD containing IGF-1R siRNA was shown to reduce IGF-1R mRNA levels by up to 95%. ELISA assay detected a similar inhibition of IGF-1R protein levels in cells transfected with IGF-1R siRNA. SW480 cells transfected with the expression vector for siRNA significantly rendered cells more sensitive to radiation and the highest radiation enhancement ratio was 2.02 ± 0.08. Conclusion. These data provide the first evidence that specific siRNA fragment (pkD-shRNA-IGF-1R-V2) targeting human IGF-1R mRNA is able to enhance colon cancer radiosensitivity. Also results indicated that, combining IGF-1R siRNA and radiation significantly enhances antitumor efficacy compared with either modality alone

  16. Regulatory proteins (inhibitors or activators) affect estimates of Msub(r) of enzymes and receptors by radiation inactivation

    International Nuclear Information System (INIS)

    The radiation-inactivation method allows the determination of the Msub(r) of enzymes and receptors by monitoring the decay of biological activity as a function of absorbed dose. The presence of regulatory or effector proteins (inhibitors or activators) associated with an enzyme or receptor, or released in the preparation after tissue homogenization, may affect the decay of biological activity. How the activity is affected, however, will depend on the type of inhibition (competitive or non-competitive), the inhibitor or activator concentration, the dissociation constant of the enzyme-effector system, and the effector Msub(r) relative to that of the enzyme. Since little is known on how effector proteins influence radiation inactivation of enzymes and receptors, we have considered a theoretical model in an effort to provide a framework for the interpretation of experimentally obtained data. Our model predicts that competitive and non-competitive inhibitors of enzymes could be distinguished by analysing irradiated samples with various substrate concentrations. Inhibitors will decrease whereas activators will increase the apparent target size of enzymes or receptors. (author)

  17. Study of the natural radiation background affected on the human body in some areas of Viet Nam

    International Nuclear Information System (INIS)

    The author had studied the natural radiation background in 68 districts belong 40 provinces and cities of Vietnam from 2002 to 2005. The estimated results clearly show that the average external irradiation dose levels and the average annual external radiation equivalent dose affected on the human body are 0.181± 0.0189 μSv/h and 1599 ± 171.8 μSv/year respectively, both are in normal limit; the highest levels are in Lai Chau district (Lai Chau province); the lowest levels are in Buon Ma Thuot city (DakLak province), Phuoc Son district (Quang Nam province), Tan An district (Long An province). The radon concentration in the human being and the average annual internal inhalation irradiation equivalent dose affected on the human beings are 26.9 ± 15.89 Bq/m3 and 392.88 ± 231.99 μSv/year respectively; the maximums are in Nha Trang city (Khanh Hoa province), Bac Binh district (Binh Phuoc province); the minimums are in Vung Tau city (Ba Ria- Vung Tau province), Tan An district (Long An province), Rach Gia district (Kien Giang province). The terrestrial radionuclide concentrations in the cereals, foodstuffs (rice, meat, vegetables), water, earth and the average annual internal irradiation equivalent dose are 829.2 ± 38.06 Bq/kg and 229.3 ± 67.70 μSv/year respectively; the highest levels are in Phong Tho district (Lai Chau province), Dien Bien city; the lowest levels are in Dong Xoai district (Binh Phuoc province), Tan An district (Long An province). The average total annual natural radiation background effective equivalent dose level affected on the human body is 2206.9 ± 529.30 μSv/year; the highest levels are in Lai Chau district (Lai Chau province); the lowest levels are in Tan An district (Long An province). The 14 maps of Natural Radiation Background in several localized regions belong 40 provinces and cities of Viet Nam had been set up. These results can reserve for serviceman and public health in the both wartime and peacetime. (author)

  18. BCL-XS adenovirus-mediated gene therapy approach sensitizes cancer cells to radiation-induced apoptosis

    International Nuclear Information System (INIS)

    Purpose: Apoptosis, a process in which a genetic program is activated ultimately leading to programmed cell death, has been shown to play a role in radiation therapy (RT)-induced cell death. We and others have previously shown that members of the bcl-2 family (including bcl-xl) protect cells from RT-induced apoptosis through p53-dependent and -independent pathways. Therefore, we postulated that inactivation of bcl-2 family members by overexpression of bcl-xs (a functional inhibitor of the bcl-2 family) would enhance RT-induced apoptosis. Overexpression of bcl-xs was achieved using two strategies: stable transfection and transient infection using an adenovirus (AV) vector. Methods: An expression plasmid encodingbcl-xs (pSFFVneo-bcl-xs) or a control plasmid (pSFFVneo) was stably transfected into MCF-7 (breast cancer), K562 (human leukemia), and FL512 (pro B-cell) cells and clonogenic survival was determined following RT. The second method used to overexpress bcl-xs involved construction of an AV vector that expresses bcl-xs by inserting the bcl-xs coding sequence into the pADRSV vector. Immunoblotting using a rabbit polyclonal antibody raised against the bcl-x protein revealed that K562 cells infected with the bcl-xs AV, but not the control AV that contains the β-galactosidase gene, expressed the 21 kDA bcl-xs protein. K562 cells were infected with the bcl-xs AV or the control AV at titres to achieve 90-95% infection. Various doses of RT were given 24 hrs following infection since maximal expression of bcl-xs was achieved at this time. Colony forming ability following RT was performed. Apoptotic death at 24 and 48 hrs following RT was assayed by flow cytometry using propidium iodide which quantitates DNA damage. Results: Bcl-xs overexpression by stable transfection in all three cell lines tested induced a marked increase in radiosensitivity. Bcl-xs overexpressing K562, FL512, and MCF-7 cells were more sensitive to RT-induced clonogenic death than their neo

  19. Direct imaging of the molecular arrangement in a radiation-sensitive polymer single crystal: poly(tetramethyl-p-silphenylene siloxane)

    International Nuclear Information System (INIS)

    A high-resolution electron micrograph of a radiation-sensitive polymer, a poly(tetramethyl-p-silphenylene siloxane) single crystal, was taken with a minimum-dose system. A resolution of 0.32 nm was attained in the image as judged from the optical diffraction pattern of the original negative. To enhance the image quality, the original micrograph was processed by optical filtering. In the processed image, individual molecules could be distinguished and their arrangement in the crystal was found to be in good agreement with an X-ray diffraction analysis of the structure. (author)

  20. Direct imaging of the molecular arrangement in a radiation-sensitive polymer single crystal: poly(tetramethyl-p-silphenylene siloxane)

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, Masaki; Ohara, Masayoshi; Isoda, Seiji; Kawaguchi, Akiyoshi; Katayama, Ken-ichi

    1989-04-01

    A high-resolution electron micrograph of a radiation-sensitive polymer, a poly(tetramethyl-p-silphenylene siloxane) single crystal, was taken with a minimum-dose system. A resolution of 0.32 nm was attained in the image as judged from the optical diffraction pattern of the original negative. To enhance the image quality, the original micrograph was processed by optical filtering. In the processed image, individual molecules could be distinguished and their arrangement in the crystal was found to be in good agreement with an X-ray diffraction analysis of the structure.

  1. Construction and expression of secreting type human TRAIL gene vector mediated by hypoxia/radiation double sensitive promoter

    International Nuclear Information System (INIS)

    Objective: To construct secreting type human TRAIL (shTRAIL) gene vector pcDNA3.1-HRE/Egr1-shTRAIL mediated by hypoxia/radiation double sensitive promoter, and observe the effect of hypoxia and radiation on shTRAIL. Methods: HRE upper and lower strands were gotten by chemical synthesis, double strands HRE was gotten by PCR; pMD19T-Egr1 was digested by Sac I and Hind III, then Egr1 was obtained, pshuttle-shTRAIL was digested by Kpn I and BamH I, then shTRAIL was obtained; HRE/Egr1 double sensitive promoter mediated shTRAIL expression vector pcDNA3.1-HRE/Egr1-shTRAIL was constructed by gene recombination technique, it was identified correctly by enzyme digestion, PCR and sequencing. A549 cells were divided into normal, hypoxia (0.1%), irradiation (6 Gy) and hypoxia + irradiation groups. Results: After enzyme digestion by BamH I and Sma I, the fragments which lengths were 1284 bp and 4 998 bp, 2 292 bp and 3 990 bp were obtained; the vector was amplified by PCR with Egr1 and shTRAIL primer, the products which lengthens were 469 bp and 820 bp were obtained; pcDNA3.1-HRE/Egr1-shTRAIL was sequenced, the result was same to designed, this demonstrated that the construction was right. The vectors were transfected into A549 cells of adenocarcinoma of lung, the expression levels of shTRAIL mRNA and protein were increased after treated with hypoxia and radiation, it had statistically significant differences compared with normal group (P<0.05), and when they were combinated, the effect was more obvious. Conclusion: Secreting type human TRAIL gene vector pcDNA3.1-HRE/Egr1-shTRAIL mediated by hypoxia/radiation double sensitive promoter is constructed successfully, and hypoxia and radiation could increase the expression of TRAIL, and they have synergetic effect. (authors)

  2. Position-sensitive liquid hydrogen targets with registration of Vavilov-Cherenkov radiation

    International Nuclear Information System (INIS)

    Long liquid hydrogen targets have been designed in which the detection and measurement of the Vavilov-Cherenkov radiation, emitted from the charged incoming particle before the interaction, give a good estimate of the interaction point position. This allows a satisfactory degree of precision in the geometrical reconstruction of the event to be maintained. (orig./HSI)

  3. Advanced data readout technique for Multianode Position Sensitive Photomultiplier Tube applicable in radiation imaging detectors

    International Nuclear Information System (INIS)

    Most of the best performing PSPMT tubes from Hamamatsu and Burle are designed with a pad-matrix anode layout. However, for obtaining a high resolution, a small-sized anode photomultiplier tubes are preferable; these tubes may have 64, 256 or 1024 anodes per tube. If the tubes are used in array to get a larger area detector, the number of analog channels may range from hundreds to thousands. Multichannel analog readout requires special electronics ICs, ASICs etc., which are attached to multichannel DAQ system. As a result, the data file and data processing time will be increased. Therefore, this readout could not be performed in a small project. Usually, most of radiation imaging applications allow the use of analog data processing in front-end electronics, significantly reducing the number of the detector's output lines to data acquisition without reducing the image quality. The idea of pad-matrix decoupling circuit with gain correction was invented and intensively tested in JLab. Several versions of PSPMT readout electronics were produced and studied. All developments were done and optimized specifically for radiation imaging projects. They covered high resolution SPECT, high speed PET, fast neutron imaging, and single tube and multi tube array systems. This paper presents and discusses the summary of the observed results in readout electronics evaluation with different PSPMTs and radiation imaging systems, as well as the advantages and limitations of the developed approach to radiation imaging detectors readout.

  4. Sphingosine analog fingolimod (FTY720) increases radiation sensitivity of human breast cancer cells in vitro.

    Science.gov (United States)

    Marvaso, Giulia; Barone, Agnese; Amodio, Nicola; Raimondi, Lavinia; Agosti, Valter; Altomare, Emanuela; Scotti, Valerio; Lombardi, Angela; Bianco, Roberto; Bianco, Cataldo; Caraglia, Michele; Tassone, Pierfrancesco; Tagliaferri, Pierosandro

    2014-06-01

    Radiotherapy is one of the most effective therapeutic strategies for breast cancer patients, although its efficacy may be reduced by intrinsic radiation resistance of cancer cells. Recent investigations demonstrate a link between cancer cell radio-resistance and activation of sphingosine kinase (SphK1), which plays a key role in the balance of lipid signaling molecules. Sphingosine kinase (SphK1) activity can alter the sphingosine-1-phosphate (S1P)/ceramide ratio leading to an imbalance in the sphingolipid rheostat. Fingolimod (FTY720) is a novel sphingosine analog and a potent immunosuppressive drug that acts as a SphK1 antagonist, inhibits the growth, and induces apoptosis in different human cancer cell lines. We sought to investigate the in vitro radiosensitizing effects of FTY720 on the MDA-MB-361 breast cancer cell line and to assess the effects elicited by radiation and FTY720 combined treatments. We found that FTY720 significantly increased anti-proliferative and pro-apoptotic effects induced by a single dose of ionizing radiation while causing autophagosome accumulation. At the molecular level, FTY720 significantly potentiated radiation effects on perturbation of signaling pathways involved in regulation of cell cycle and apoptosis, such as PI3K/AKT and MAPK. In conclusion, our data highlight a potent radiosensitizing effect of FTY720 on breast cancer cells and provide the basis of novel therapeutic strategies for breast cancer treatment. PMID:24657936

  5. Sensitiveness to cosmic radiation: on some aspects of data collection and their representation

    International Nuclear Information System (INIS)

    During simulation of cosmic radiation effects, the energy deposition by length unit is altered because of energy lowering along the range. This mechanism is illustrated by exhaustive data got from the microprocessor type 2901. Wrong conclusions may be deduced concerning behavior in space field. New representations of cross sections are presented; they lead to safer predictions on behavior in space environment

  6. Sensitivity of APSIM/ORYZA model due to estimation errors in solar radiation

    NARCIS (Netherlands)

    Heinemann, A.B.; Oort, van P.A.J.; Simoes Fernandes, D.; Maia, A.H.N.

    2012-01-01

    Crop models are ideally suited to quantify existing climatic risks. However, they require historic climate data as input. While daily temperature and rainfall data are often available, the lack of observed solar radiation (Rs) data severely limits site-specific crop modelling. The objective of this

  7. Characterization of pH-sensitive Poly (acrylic acid-co-N-vinyl-2-pyrrolidone) Hydrogels Prepared by Gamma Radiation

    Institute of Scientific and Technical Information of China (English)

    YANG Ming-cheng; HE Su-qin; LIU Wen-tao; SONG Hong-yan; ZHU Cheng-shen

    2007-01-01

    The pH-sensitive copolymer hydrogels were prepared with the monomers of acrylic acid and N-vinyl-2-pyrrolidone based on gamma radiation technique. The morphology of the hydrogels was monitored by using scanning electron microscope. The influence of absorbed dose, monomer compasition and concentration on the swelling ratio (SR) of the hydrogels were investigated in detail. The effect of pH and temperature of the swelling medium on the swelling behavior of the hydrogels were also examined. The results show that the SR of the copolymer hydrogels decreases with the monomer concentration and absorbed dose increasing. The copolymer hydrogels show a better pH-sensitive behavior. In alkaline solution, the SR of the hydrogels is much higher than in acid solution.

  8. Research on influence of temporary distribution of power of laser radiation with a hybrid processing on a depth heat affected zone

    International Nuclear Information System (INIS)

    Investigations on the influence of the temporal distribution of the laser radiation power per pulse of hybrid processing on a depth heat affected zone. Recommendations on use of specific distribution of the laser radiation power in the combined laser and plasma processing for decrease in energy consumption

  9. Synthesis parameters affecting the exoemission properties of alpha aluminas. [X radiation, beta particles

    Energy Technology Data Exchange (ETDEWEB)

    Hugo, J.F.; Turpin, D.; Guilhot, B. (Ecole Nationale Superieure des Mines, 42 - Saint-Etienne (France). Centre de Chimie Physique); Petel, M. (CEA Centre d' Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire)

    1983-01-01

    Thermally stimulated exoelectron emission (TSEE) is used in various fields of solid state physics. This technique was applied to gain an understanding of the mechanical and thermal effects affecting inorganic solids during the preparation phase. The work carried out supplements earlier experiments on the detection by thermoluminescence of defects created in solids, and considers the possibility of applying TSEE to the study of the reactivity of solids. The different stages in the preparation of alumina are described and attempts are made to correlate their effects on triboemission glow curves and TSEE emitted after irradiation.

  10. Model of chronic local irradiation in the brain. Rep. 1. A point of radiation affection

    Energy Technology Data Exchange (ETDEWEB)

    Sataev, M.M. (Uzbekskij Nauchno-Issledovatel' skij Inst. Onkologii i Radiologii, Tashkent (USSR))

    Radionecrosis of tissues was detected after implantation of /sup 90/S-/sup 90/Y sources (0.5-0.2 Gy/h) to the rabbit brain. A repair inflammatory reaction developed around the point of affection which resulted, at a dose of 0.5 Gy/h, in the formation of the connective tissue capsules or gliomesencymal cicatrices, or in the diffuse, hyperplasia of cell elements of neuroglia, membranes and vessels of the brain at doses of 1.4 to 2.0 Gy/h. This is the reason for the appearance of focal epitheliocellular granulomas.

  11. Folic acid deficiency increases sensitivity to genome damage by ionising radiation

    International Nuclear Information System (INIS)

    Folic acid deficiency can lead to uracil misincorporation and disable DNA repair, by decreasing thymidine concentration. It is hypothesized that folic acid is an important micronutrient in the prevention of chromosome damage induced by gamma-irradiation. In this study the impact of folic acid deficiency on the chromosome damage and chromosome 21 aneuploidy by gamma-radiation was determined using the cytokinesis-block micronucleus assay in long term WIL2-NS cultures in cell culture medium with 4 different folic acid concentrations (0.2 nM, 2 nM, 20 nM and 200 nM). The study showed a significant increase of 55.5% in micronucleus frequency with decreasing folic acid concentration (P < 0.0001). Additionally, there was a significant difference of 46.5% and 50.1% in micronucleus frequency and of nucleoplasmic bridge frequency, respectively, between the control and irradiated (1.5 Gy) group (P < 0.05). Folic acid deficiency caused an increase of 51.7% in micronucleus frequency (P < 0.0001) and of 7.1% nucleoplasmic bridge frequency (P = 0.0280) in irradiated cultures when compared to irradiated folic acid replete cultures. Folic acid deficiency and gamma-radiation were shown to have a significant interactive effect on micronucleus frequency (Two-way ANOVA, P < 0.0001). Apoptosis and necrosis were increased by folic acid deficiency but they were not significantly altered by ionising radiation exposure. Chromosome 21 aneuploidy was significantly increased (P <0.05) by folic acid deficiency but not by ionising radiation and there was no significant interaction between these two factors. The results show that folic acid deficiency induces chromosome 21 aneuploidy by non-disjunction as well as inducing chromosome breaks and chromosome rearrangements. In conclusion, folic acid deficiency interacts significantly with ionising radiation in inducing chromosome damage that leads to the formation of micronuclei (e.g. chromosome breaks and chromosome loss)

  12. The role of autophagy in sensitizing malignant glioma cells to radiation therapy

    Institute of Scientific and Technical Information of China (English)

    Wenzhuo Zhuang; Zhenghong Qin; Zhongqin Liang

    2009-01-01

    Malignant gliomas representthe majority of primary brain tumors.The current standard treatments for malignant gliomas include surgical resection,radiation therapy,and chemotherapy.Radiotherapy,a standard adjuvant therapy,confers some survival advantages,but resistance of the glioma cells to the efficacy of radiation limits the success of the treatment.The mechanisms underlying glioma cell radioresistance have remained elusive.Autophagy is a protein degradation system characterized by a prominent formation of double-membrane vesicles in the cytoplasm.Recent studies suggest that autophagy may be important in the regulation of cancer development and progression and in determining the response of tumor cells to anticancer therapy.Also,autophagy is a novel response of glioma cells to ionizing radiation.Autophagic cell death is considered programmed cell death type Ⅱ,whereas apoptosis is programmed cell death type Ⅰ.These two types of cell death are predominantly distinctive,but many studies demonstrate a cross-talk between them.Whether autophagy in cancer cells causes death or protects cells is controversial.The regulatory pathways of autophagy share several molecules.P13K/Akt/Mtor,DNA-PK,tumor suppressor genes, mitochondrial damage,and lysosome may play important roles in radiation-induced autophagy in glioma cells.Recently,a highly tumorigenic glioma tumor subpopulation,termed cancer stem cell or tumor-initiating cell,has been shown to promote therapeutic resistance.This review summarizes the main mediators associated with radiation-induced autophagy in malignant glioma cells and discusses the implications of the cancer stem cell hypothesis for the development of future therapies for brain tumors.

  13. Natural Radiation for Identification and Evaluation of Risk Zones for Affectation of Activated Faults in Aquifer Overexploited.

    Science.gov (United States)

    Ramos-Leal, J.; Lopez-Loera, H.; Carbajal-Perez, N.

    2007-05-01

    In basins as Mexico, Michoacán, Guanajuato, Queretaro, Aguascalientes and San Luis Potosi, the existence of faults and fractures have affected the urban infrastructure, lines of conduction of drinkable water, pipelines, etc., that when not being identified and considered, they don't reflect the real impact that these cause also to the aquifer system, modifying the permeability of the means and in occasions they work as preferential conduits that communicate hydraulically potentially to the aquifer with substances pollutants (metals, fertilizers, hydrocarbons, waste waters, etc.) located in the surface. In the Valley of San Luis Potosi, Villa of Reyes, Arista, Ahualulco and recently The Huizache-Matehuala is being strongly affected by faulting and supposedly due cracking to subsidence, however, the regional tectonic could also be the origin of this phenomenon. To know the origin of the faults and affectation to the vulnerability of the aquifer few works they have been carried out in the area. A preliminary analysis indicates that it is possible that a tectonic component is affecting the area and that the vulnerability of the aquifer in that area you this increasing. Before such a situation, it is necessary to carry out the isotopic study of the same one, for this way to know among other things, isotopic characterization, recharge places and addresses of flow of the groundwater; quality of waters and the behavior hydrochemistry with relationship to the faults. High radon values were measured in San Luis Potosi Valley, the natural source of radon could be the riolites and however, these are located to almost a once thousand meters deep for what the migration of the gas is not very probable. The anomalies radiometrics was not correlation with the faults in this case. In some areas like the Valley of Celaya, the origin of the structures and the tectonic activity in the area was confirmed, identifying the structural arrangement of the faulting, the space relationships

  14. Effect of intense background radiation on the sensitivity of a laser receiver with an iodine active quantum filter

    International Nuclear Information System (INIS)

    The effect of background light on the sensitivity of a laser receiver with an iodine active quantum filter (λ=1.315 μm) was theoretically and experimentally investigated. Upon the reception of a 40-ns pulsed signal against the background of 2.5-fold attenuated radiation of a pulsed light source with a brightness temperature of 4 x 104 K, the sensitivity of this receiver for a signal-to-noise ratio of three and a diffraction-limited acceptance angle was experimentally shown to be equal to 20 photons, which exceeds the quantum limit by about a factor of two. This is consistent with the results of theoretical treatment and suggests that upon the detection of optical signals against the background of the solar disk, the sensitivity of this receiver should decrease by only 12%. This receiver was compared with a receiver employing a photomultiplier of the visible range. Upon the reception of optical signals with the same parameters against the background of the solar disk and an interference filter with a transmission band width of 5 nm, the sensitivity of a receiver equipped with an FEU-115 photomultiplier was shown to be equal to about 1400 photons for a signal-to-noise ratio of three. (laser applications and other topics in quantum electronics)

  15. Sensitivity of the photodissociation of NO2, NO3, HNO3 and H2O2 to the solar radiation diffused by the ground and by atmospheric particles

    International Nuclear Information System (INIS)

    The diffusion of solar radiation by atmospheric molecules and aerosols and by ground albedo affects the photodissociation rates of atmospheric species relevant to the ozone chemistry. In this paper, a previous investigation on the photodissociation of O3 is extended to NO2, NO3, HNO3, H2O2. Because of the different character of the absorption spectra of these species, the behaviour of photodissociation profiles with height and their sensitivity to such factors as ground albedo, aerosol loads, solar zenith angle are somewhat different. The results show that the presence of the aerosols usually enhances the photodissociation in the upper troposphere and in the stratosphere, because of scattering, but tends to reduce it at low heights because of the increased extinction. Enhancements in the photodissociation coefficients are as high as 20 to 40% for low values of the albedo and large aerosol loads such as those obtained after a volcanic eruption. On the other hand, at large values of the albedo, the effect of aerosols is mainly in attenuating the radiation going into and coming from the ground and their presence can lead to reduced photolysis even in the stratosphere. (author)

  16. A Genomewide Screen in Schizosaccharomyces pombe for Genes Affecting the Sensitivity of Antifungal Drugs That Target Ergosterol Biosynthesis

    OpenAIRE

    Fang, Yue; Hu, Lingling; Zhou, Xin; Jaiseng, Wurentuya; Zhang, Ben; Takami, Tomonori; Kuno, Takayoshi

    2012-01-01

    We performed a genomewide screen for altered sensitivity to antifungal drugs, including clotrimazole and terbinafine, that target ergosterol biosynthesis using a Schizosaccharomyces pombe gene deletion library consisting of 3,004 nonessential haploid deletion mutants. We identified 109 mutants that were hypersensitive and 11 mutants that were resistant to these antifungals. Proteins whose absence rendered cells sensitive to these antifungals were classified into various functional categories,...

  17. Rooting, growth, and color mutation of poinsettias affected by gamma radiation

    International Nuclear Information System (INIS)

    This experiment was carried out to investigate the effects of gamma-radiation on the rooting, growth, and color mutation in poinsettia. Using 10 poinsettia varieties ('Lollipop', 'Little Peace', 'Happy Day', 'Early Bird', 'Pixy Red', 'Happy Time', 'Heidi', 'Red Bell', 'Clara', and 'Scarlet') bred by National Institute of Horticultural and Herbal Science, 100 Gy of gamma ray was irradiated at the stage of callused cuttings. Four weeks after sticking cuttings in the rooting media, 8 cultivars showed 100% of root formation, but 'Early Bird' rooted 24.4% and even died off during the cutting propagation. After planting rooted cuttings, survival rate until flowering time varied among irradiated cultivars. While 'Pixy Red' and 'Heidi' survived about 98%, 'Clara', 'Happy Day', and 'Early Bird' survived lesser than 30%. All irradiated plants showed remarkably shorter plant height, lesser branch numbers than non-irradiated control plants. Thirty color mutants were obtained among 281 plants survived until flowering time. Nine were complete color mutated branches, whereas 21 mutants were partially color mutated bracts and transitional leaves. Color patterns mutated by 100 Gy of gamma ray were divided into pink, hot pink, light red and spotted (pink spots with red main color). Pink mutants were commonly obtained. Complete color mutants were discovered from 4 plants of 'Pixy Red', 2 plants of 'Red Bell' and 3 plants of Lollipop

  18. Radiation treatment of glottic squamous cell carcinoma, Stage I and II: analysis of factors affecting prognosis

    International Nuclear Information System (INIS)

    Purpose: At least in some European Countries, there is still considerable controversy regarding the choice between surgery and radiotherapy for the treatment of patients with early laryngeal-glottic carcinoma. Methods and Materials: Two hundred and forty-six patients with laryngeal-glottic neoplasms, Stage I-II, were treated with radical radiotherapy. Before radiotherapy the patients were evaluated to determine the surgical procedure of choice. Either 66-68.4 Gy (33-38 fractions) or 63-65 Gy (28-29 fractions) of radiation therapy (RT) were administered. The overall disease free survival was determined for each subgroup of patients. Univariate and multivariate analyses were performed to determine significant prognostic variables. Results: Five- and 10-year overall survival rates were 83 and 72%, respectively. At a median follow-up of 6 years 204 patients are alive and disease free. No patient developed distant metastases. One patient died of a large local recurrence, 38 patients died of causes unrelated to their tumor, and 3 patients were lost to follow-up. The multivariate analysis confirmed that performance status (PS), macroscopic presentation of the lesion, and persistence of dysphonia after radiotherapy are significant prognostic factors. Conclusions: According to the multivariate analysis, the patients with PS >80 and with exophytic lesions are eligible for radical RT. The surgical procedure proposed for each patient was not found to be an independent prognostic factor

  19. Sensitization and protection in the radiation chemistry of biologically active DNA

    International Nuclear Information System (INIS)

    The results are reported of a study of the effects of the well-known sensitizers paranitroacetophenone (PNAP), triacetone-amine-N-oxyl (TAN) and oxygen, and of the protector cysteamine on the radiosensitivity of purified biologically active DNA of bacteriophages. Irradiation conditions are stated. The results are discussed. (U.K.)

  20. Does repair or stage sensitivity determine the shape of time-effect curves in radiation mutagenesis

    International Nuclear Information System (INIS)

    Seedlings of Crepis capillaris were irradiated after pulse labelling with tritiated thymidine, and both chromosomal aberrations and the presence of silver grains were recorded in the same metaphase cells at various intervals throughout the whole mitotic cycle. The following results were obtained: a) irradiated roots were homogeneous with respect to the number of aberrations, and heterogeneous with respect to the labelling index; b) time-effect curves for labelled and unlabelled cells showed no significant difference from one another; c) no significant quantitative difference in aberration spectra produced in S and G2 stages was found. These results support the view that the major factor which determines both quantitative and qualitative variation in the production of chromosomal aberrations by radiation is the time lapse between irradiation and fixation rather than the relation of the time of irradiation to the time of DNA synthesis. In addition, it was found that labelling with tritiated thymidine modifies the effect of radiation in chromosomes

  1. Sensitivity of microorganisms be distributed through Japanese tea manufacturing process by radiation

    International Nuclear Information System (INIS)

    The number of bacteria adhering to Japanese tea is 107∼108 cfu/g in picked fresh tea leaves (almost radiation irresistance), decreasing every heat-treatment in manufacturing process to 103∼104 cfu/g in tea on the market (only radiation resistance). Still more, its decreasing one figures after half a year by effect of anti-bacterium component contained Japanese tea. The number of fungi adhering to almost samples is below 50cfu/g, but that adhering to some powdered tea is 102 cfu/g. At heat treatment (80degC, 15min), the number of bacteria decrease very little. The other side, by EB-irradiated treatment (2kGy), its below 102 cfu/g (D10-value; 1.4∼3.8kGy). The needed dose to decrease 102 cfu/g is 0.9∼2.5kGy. (author)

  2. Thermal Enhancement with Optically Activated Gold Nanoshells Sensitizes Breast Cancer Stem Cells to Radiation Therapy

    OpenAIRE

    Atkinson, Rachel L; ZHANG, MEI; Diagaradjane, Parmeswaran; Peddibhotla, Sirisha; Contreras, Alejandro; Hilsenbeck, Susan G; Woodward, Wendy A.; Krishnan, Sunil; Chang, Jenny C.; Rosen, Jeffrey M

    2010-01-01

    Breast cancer metastasis and disease recurrence are hypothesized to result from residual cancer stem cells, also referred to as tumor-initiating cells, which evade initial treatment. Using both syngeneic mouse and human xenograft models of triple-negative breast cancer, we have demonstrated that a subpopulation enriched in cancer stem cells was more resistant to treatment with 6 gray of ionizing radiation than the bulk of the tumor cells, and accordingly their relative proportion increased 48...

  3. Sensitivity of modelled sulfate radiative forcing to DMS concentration and air-sea flux formulation

    OpenAIRE

    Tesdal, J.-E.; Christian, J.R; Monahan, A.H.; Von Salzen, K.

    2015-01-01

    In this study, we use an atmospheric general circulation model with explicit aerosol chemistry (CanAM4.1) and several climatologies of surface ocean DMS concentration to assess uncertainties about the climate impact of ocean DMS efflux. Despite substantial variation in the spatial pattern and seasonal evolution of simulated DMS fluxes, the global mean radiative forcing is approximately linearly proportional to the global mean surface flux of DMS; the spatial and temporal dis...

  4. Contribution of autophagy inhibitor to radiation sensitization in nasopharyngeal carcinoma cells

    International Nuclear Information System (INIS)

    Objective: To investigate the role of autophagy in radiation-induced death response of human nasopharyngeal carcinoma cells. Methods: MTT method was used to detect cell viability of CNE-2 cells in different time after irradiation. Clonogenic survival assay was used to evaluate the effect of autophagy inhibitor (chloroquine phosphate) and autophagy inductor (rapamycin) on radiosensitivity of nasopharyngeal carcinoma cells.Cell apoptosis was assessed by flow cytometry. The expressions of LC3 and P62 were measured with Western blot. Cell ultrastructural analysis was performed under an electron microscope.Results Irradiation with 10 Gy induced a massive accumulation of autophagosomes accompanied with up-regulation of LC3-Ⅱ expression in CNE-2 cells. Compared with radiation alone, chloroquine phosphate (CDP) enhanced radiosensitivity significantly by decreasing cell viability (F=25.88, P<0.05), autophagic ratio (F=105.15, P<0.05), and LC3-Ⅱ protein level (F=231.68, P<0.05), while up-regulating the expression of P62 (F=117.52, P<0.05). Inhibition of autophagy increased radiation-induced apoptosis (F=143.72, P<0.05). Rapamycin (RAPA) also significantly decreased cell viability, but increased autophagic ratio and LC3-Ⅱ protein level while down-regulated the expression of P62. Induction of autophagy increased radiation-induced apoptosis (F=167.32, P<0.05). Conclusions: Blockage of autophagy with CDP could enhance radiosensitivity in human nasopharyngeal carcinoma cells, suggesting that inhibition of autophagy could be used as an adjuvant treatment to nasopharyngeal carcinoma. (authors)

  5. Neutron and gamma-radiation sensitivity of plasmid DNA of varying superhelical density

    International Nuclear Information System (INIS)

    Several families of negatively supercoiled topoisomers of plasmid pIBI30 were prepared by a modification of the procedure of Singleton and Wells. The average superhelical density (σ) was determined by two-dimensional agarose gel electrophoresis and varied from -0.010 to -0.067, corresponding to a change in the number of supercoils from 3 to 19 and an effective volume change from 1.6 x 108 to 4 x 108 angstrom 3. Samples were exposed to either fission-neutron or 60Co γ radiation and assayed for single-strand breaks by agarose gel electrophoresis. Form I DNA for all topoisomers decreased exponentially with increasing dose. The D37 values for both neutron and γ radiation increased monotonically with increasing |σ|. Using a branched plectonemic (interwound) form for DNA over the range of σ studied and standard (single-hit) target theory, a quantitative linear fit to (D37-1) as a function of the effective DNA radius, S(angstrom), was obtained. The model predicts that both the slope (a) and the intercept (b) of (D37)-1 as a function of S(angstrom) are directly proportional to the length of DNA and the radiation fluence. Furthermore, the ratio b/a (= ro) at σ = 0 depends only on the ionic strength of the medium and is independent of the radiation source parameters. Our results support the model and we calculate ro = 13.4 ± 1.4 nm, a value consistent with other investigations. Our results are consistent with studies using 137Cs but disagree with data obtained for X rays. 31 refs., 6 figs., 1 tab

  6. Sensitivity of radiative properties of persistent contrails to the ice water path

    Directory of Open Access Journals (Sweden)

    R. R. De León

    2012-09-01

    Full Text Available The dependence of the radiative properties of persistent linear contrails on the variability of their ice water path is assessed in a two-stream radiative transfer model. It is assumed that the ice water content and the effective size of ice crystals in aged contrails do not differ from those observed in natural cirrus; the parameterization of these two variables, based on a correlation with ambient temperature derived from in situ observations, allows a more realistic representation than the common assumption of fixed values for the contrail optical depth and ice crystal effective radius.

    The results show that the large variability in ice water content that aged contrails may share with natural cirrus, together with an assumed contrail vertical thickness between 220 and 1000 m, translate into a wider range of radiative forcings from linear contrails [1 to 66 m Wm−2] than that reported in previous studies, including IPCC's [3 to 30 m Wm−2]. Further field and modelling studies of the temporal evolution of contrail properties will thus be needed to reduce the uncertainties associated with the values assumed in large scale contrail studies.

  7. Reduction of residual n-butylacrylate sensitizer in radiation vulcanized natural rubber latex

    International Nuclear Information System (INIS)

    Radiation vulcanisation of natural rubber latex needs n-butyl acrylate (n-BA) to lessen required irradiation dose. Considerable amount of n-BA remains in the latex after the completion of radiation vulcanisation and tends to pollute the working environment in a dipping factory. A study has been carried out to reduce the residual n-BA after the radiation vulcanization. About 40% of added n-BA was found in the latex after irradiation to 20 kGy. Hydrolysis of n-BA was effective for reduction of the residual n-BA in the latex. No n-BA was found in the latex when the latex was stored for 4 weeks at room temperature due to its hydrolysis. Heating of the latex was effective to accelerate the rate of hydrolysis of n-BA. Almost all of n-BA in the latex was hydrolysed when the latex was heated for 4 hours at 800 degree C. Tensile strength of the latex films slightly decreased by heating treatment of the latex, but gradually recovered as storage time extended. Low viscosity was attained by the heat treatment of the latex

  8. Sensitization of the analytical methods for photoneutron calculations to the wall concrete composition in radiation therapy

    International Nuclear Information System (INIS)

    The effect of wall material on photoneutron production in radiation therapy rooms was studied using Monte Carlo (MC) simulations. An analytical formula was proposed to take into account the concrete composition in photoneutron dose calculations. Using the MCNPX MC code, the 18 MV photon beam of the Varian Clinac 2100 and a typical treatment room with concrete compositions according to report No. 144 of National Council of Radiation Protection (NCRP) were simulated. Number of room produced photoneutrons per Gray of X-ray at the isocenter was determined for different types of concrete and named as “QW”. This new factor was inserted in the used formula for photoneutron fluence calculations at the inner entrance of maze. The photoneutron fluence was calculated using new proposed formula at the inner entrance of maze for all studied concretes. The difference between conventional and proposed equations varied from 11% to 46% for studied concretes. It was found that room produced photoneutrons could be significant for high density concretes. Additionally, applying the new proposed formula can consider the effect of wall material composition on the photoneutron production in high energy radiation therapy rooms. Further studies to confirm the accuracy of newly developed method is recommended.

  9. The sensitivity of Mycoplasma mycoides var. capri cells to γ-radiation after growth in a medium containing the thymine analogue 5-vinyluracil

    International Nuclear Information System (INIS)

    Cells of the bacterium Mycoplasma mycoides var. capri grown in a medium containing the potential radiation-sensitive thymine analogue 5-vinyluracil show a 3-fold increase in sensitivity towards irradiation of a dose of 15 krads of γ-rays. (author)

  10. Micro glial responses after focal radiation-induced injury are affected by α-difluoro methylornithine

    International Nuclear Information System (INIS)

    Purpose: The objective of this study was to quantify microglial and astrocytic cell responses after focal 125I irradiation of normal brain and to determine the effects of an intravenous infusion of α-difluoro methylornithine (DFMO) on those responses. Methods and Materials: Adult beagle dogs were irradiated using high activity 125I sources. Saline or DFMO (75 mg/kg/day) was infused for 18 days, and 1 to 10 weeks later brain tissues were collected. Immunohistochemical stains were used to label phagocytes and amoeboid microglia (lectin RCA-1), astrocytes (GFAP), and cells synthesizing deoxyribonucleic acid (DNA) (BrdU). Cell densities (cells/mm2) and BrdU labeling indices were quantified. Results: In dogs infused with saline, increases in phagocytes and amoeboid microglia were observed at 1-2 weeks and 4 weeks, respectively. The labeling indices for phagocytes and amoeboid microglia peaked at 4 weeks with maximum values of 4.8 and 13.4%, respectively. Astrocyte cell numbers increased from 2-6 weeks following irradiation; increased labeling indices were observed after 2 weeks. An infusion of DFMO significantly suppressed BrdU labeling and delayed the increase in cell numbers for phagocytes and amoeboid microglia. In both treatment groups, the proportion of total BrdU labeling accounted for by phagocytes was maximum 1 week after irradiation and then decreased. The proportion of total BrdU labeling accounted for by amoeboid microglia and astrocytes was zero for 2 weeks and then increased. Conclusions: Microglial reactions after focal irradiation involve the phagocytic and amoeboid cell forms and are characterized by increased BrdU uptake and increased cell number. DFMO significantly alters these responses. Changes in astrocyte cell number and BrdU labeling may be related to changes in microglia. Studies of cell responses and their modification may lead to a better understanding of the pathogenesis of radiation injury, and to new strategies to optimize the use of

  11. Radiation effects on the stability of benzimidazole, which directly affects the stability of human DNA

    International Nuclear Information System (INIS)

    As all of us know that DNA is the genetic material and that is therefore stood at the very center of the study of life. Among the four important nitrogenous bases found in DNA one is purine which is nothing but a benzimidazole structure substituted by two nitrogens at 1 and 3 positions. Denaturation and renaturation duo to radiation are the two important incidents in DNA life which are the reason of many diseases and also the remedy of many diseases. These two incidents occur due to environmental effect on the parent part of DNA such as purine or we may say that benzimidazole structure. Since benzimidazole is an important part of human DNA structure so its response on different environment causes e huge effect on human gen. To study such response different types of benzimidazole molecules have been studied and two of such benzimidazole molecules are 2-Acetyl Benzomidazole (2ABI) and 2-Benzoyl Benzimidazole (2BBI). Usually these molecules show excited state proton transfer characteristics in polar and nonpolar environment. Proton transfer effect is very important behavior in DNA bases which is the fundamental phenomenon of different drug designing. To control such effect or to produce the effect as much as we want we have tried to restrict the molecule in different nano cavities. Michroheterogeneous media such as micelles as usual has enormous environmental effect on charge transfer phenomenon. The specialty of this media is that they have an ability to concentrate guest molecules into relatively small effective volumes and then to promote the re-encounter of such molecules. This property also makes micelles a good device for inducing efficient electrostatic interactions between the micelle head groups and the guest molecules. This electrostatic interaction has a direct effect on the stability of 2ABI and 2BBI molecule in ground state as well as in excited state due to micellization and this stability has enormous effect on human gene stability. (authors)

  12. Radiation synthesis of a water-soluble temperature sensitive polymer, activated copolymer and applications in immobilization of proteins

    International Nuclear Information System (INIS)

    In this work the radiation polymerization of N-isopropylacrylamide (NIPAAM) in aqueous solutions has been carried out and a water-soluble, temperature sensitive polymer and copolymer were obtained by using γ-rays from Co-60 source at room temperature. We have gained the optimum dose and dose-rate of radiation synthesis of linear polyNIPAAM through determining conversion yield and viscosity. In order to immobilize protein (BSA) and enzyme (HRP) into this water-soluble polymer, we prepared an activated copolymer, poly(N-isopropylacrylamide-co-N-acryloxysuccinimide). The BSA and HRP has been immobilized onto the activated copolymer. The BSA (HRP)/copolymer conjugates still kept the original thermally sensitive properties of the linear polyNIPAAM. The conjugation yield of BSA to the activated copolymer decreased with increasing dose. Immobilized HRP was stable at 0oC for a long time and has, at least, 4 days stability at room temperature. Immobilized HRP activity was lowered when the temperature was raised. This phenomenon was reversible and the immobilized HRP regained activity. The optimum pH of the immobilized HRP shifted from ca.5 upward to ca. 7. (author)

  13. TERRA Expression Levels Do Not Correlate With Telomere Length and Radiation Sensitivity in Human Cancer Cell Lines

    Directory of Open Access Journals (Sweden)

    Alexandra eSmirnova

    2013-05-01

    Full Text Available Mammalian telomeres are transcribed into long non-coding telomeric RNA molecules (TERRA that seem to play a role in the maintenance of telomere stability. In human cells, CpG island promoters drive TERRA transcription and are regulated by methylation. It was suggested that the amount of TERRA may be related to telomere length. To test this hypothesis we measured telomere length and TERRA levels in single clones isolated from five human cell lines: HeLa (cervical carcinoma, BRC-230 (breast cancer, AKG and GK2 (gastric cancers and GM847 (SV40 immortalized skin fibroblasts. We observed great clonal heterogeneity both in TRF (Terminal Restriction Fragment length and in TERRA levels. However, these two parameters did not correlate with each other. Moreover, cell survival to γ-rays did not show a significant variation among the clones, suggesting that, in this cellular system, the intra-population variability in telomere length and TERRA levels does not influence sensitivity to ionizing radiation. This conclusion was supported by the observation that in a cell line in which telomeres were greatly elongated by the ectopic expression of telomerase, TERRA expression levels and radiation sensitivity were similar to the parental HeLa cell line.

  14. Variability of individual normal tissue radiation sensitivity. An international empirical evaluation of endogenous and exogenous

    International Nuclear Information System (INIS)

    Background: The variability of normal-tissue response is of major concern for radiation therapy. Multiple endogenous and exogenous factors are qualitatively known to alter the acute and late tissue response. Which of them are regarded most important by the European radiation oncologists and what is, empirically, their quantitative influence on the acute or late tissue tolerance? Methods: In August 1997, we sent a questionnaire to 255 European radiation oncology departments. Among others, the questionnaire asked for endogenous and exogenous factors modifying the tissue response to radiation therapy and their quantitative influence on the acute and late radiation morbidity (TD5/5). Fifty-five questionnaires (21.5%) were answered. Results: Empirically, the most important endogenous factors to modify the acute tissue tolerance are (a) metabolic/other diseases with macro- or microangiopathia (17 answers [a]/32% mean decrease of tissue tolerance), (b) collagen diseases (9 a/37%) and (c) immune diseases (5 a/53%). As endogenous response modifiers for the TD5/5 are recognized (a) metabolic or other diseases leading to marcro- or microangiopathia (15 a/31%), (b) collagen diseases (11 a/38%) and (c) immune diseases (2 a/50%). Inflammations from any reason are assumed to alter the acute tissue tolerance by (6 a/26%) and the TD5/5 by (10 a/24%). Exogenous modifiers of the acute tissue response mentioned are (a) smoking (34 a/44%), (b) alcohol (23 a/45%), (c) nutrition/diets (16 a/45%), (d) hygiene (9 a/26%) and (e) medical therapies (10 a/37%). Exogenous factors assumed to influence the TD5/5 are (a) smoking (22 a/40%), (b) alcohol (15 a/38%), (c) nutrition/diets (9 a/48%), (d) hygiene (5 a/34%) and (e) medical therapies (10 a/30%). Conclusions: Exogenous factors are regarded more important by number and extent on the acute and late tissue response than endogenous modifiers. Both may have an important influence on the individual expression of normal tissue response. (orig.)

  15. Short-term UV-B radiation affects photosynthetic performance and antioxidant gene expression in highbush blueberry leaves.

    Science.gov (United States)

    Inostroza-Blancheteau, Claudio; Acevedo, Patricio; Loyola, Rodrigo; Arce-Johnson, Patricio; Alberdi, Miren; Reyes-Díaz, Marjorie

    2016-10-01

    The impact of increased artificial UV-B radiation on photosynthetic performance, antioxidant and SOD activities and molecular antioxidant metabolism responses in leaves of two highbush blueberry (Vaccinium corymbosum L. cv. Brigitta and Bluegold) genotypes was studied. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 W m(-2) of biologically-effective UV-B irradiance for 0-72 h. Our findings show that net photosynthesis (Pn) decreased significantly in Bluegold, accompanied by a reduction in the effective quantum yield (ФPSII) and electron transport rate (ETR), especially at the highest UV-B irradiation. On the other hand, Brigitta showed a better photosynthetic performance, as well as a clear increment in the antioxidant activity response that could be associated with increased superoxide dismutase activity (SOD) in the early hours of induced UV-B stress in all treatments. At the molecular level, the expression of the three antioxidant genes evaluated in both genotypes had a similar tendency. However, ascorbate peroxidase (APX) expression was significantly increased (6-fold) in Bluegold compared to Brigitta. Thus, the reduction of Pn concomitant with a lower photochemical performance and a reduced response of antioxidant metabolism suggest that the Bluegold genotype is more sensitive to UV-B radiation, while Brigitta appears to tolerate better moderate UV-B irradiance in a short-term experiment. PMID:27343876

  16. High-throughput identification of ionizing radiation-sensitive plant genes and development of radiation indicator plant and radiation sensing Genechip

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Sub; Kim, Jinbaek; Ha, Bokeun; Kim, Sang Hoon; Kim, Sunhee

    2013-05-15

    Physiological analysis of monocot model plant (rice) in response to ionizing radiation (cosmic-ray, gamma-ray, Ion beam). - Identification of antioxidant characters through cytochemical analysis. - Comparison of antioxidant activities in response to ionizing irradiation. - Evaluation of anthocyanin quantity in response to ionizing irradiation. Ionization energy response gene family analysis via bioinformatic validation. - Expression analysis of monocot and dicot gene families. - In silico and bioinformatic approach to elucidate gene function. Characterization and functional analysis of genes specifically expressed in response to ionizing irradiation (cosmic-ray, gamma-ray, Ion beam). - High throughput trancriptomic analysis of plants under ionizing radiation using microarray. - Promotor and cis-element analysis of genes specifically expressed in response to ionizing radiation. - Validation and function analysis of candidate genes. - Elucidation of plant mechanism of sensing and response to ionization energy. Development of bioindicator plants detecting ionization energy. - Cloning and identification of 'Radio marker genes (RMG)'. - Development of Over-expression (O/E) or Knock-out (K/O) plant using RMG. Development of Genechip as an ionization energy detector. - Expression profiling analysis of genes specifically expression in response to ionization energy. - Prepare high-conserved gene specific oligomer. - Development of ionization energy monitoring Genechip and application.

  17. High-throughput identification of ionizing radiation-sensitive plant genes and development of radiation indicator plant and radiation sensing Genechip

    International Nuclear Information System (INIS)

    Physiological analysis of monocot model plant (rice) in response to ionizing radiation (cosmic-ray, gamma-ray, Ion beam). - Identification of antioxidant characters through cytochemical analysis. - Comparison of antioxidant activities in response to ionizing irradiation. - Evaluation of anthocyanin quantity in response to ionizing irradiation. Ionization energy response gene family analysis via bioinformatic validation. - Expression analysis of monocot and dicot gene families. - In silico and bioinformatic approach to elucidate gene function. Characterization and functional analysis of genes specifically expressed in response to ionizing irradiation (cosmic-ray, gamma-ray, Ion beam). - High throughput trancriptomic analysis of plants under ionizing radiation using microarray. - Promotor and cis-element analysis of genes specifically expressed in response to ionizing radiation. - Validation and function analysis of candidate genes. - Elucidation of plant mechanism of sensing and response to ionization energy. Development of bioindicator plants detecting ionization energy. - Cloning and identification of 'Radio marker genes (RMG)'. - Development of Over-expression (O/E) or Knock-out (K/O) plant using RMG. Development of Genechip as an ionization energy detector. - Expression profiling analysis of genes specifically expression in response to ionization energy. - Prepare high-conserved gene specific oligomer. - Development of ionization energy monitoring Genechip and application

  18. Evaluation of some properties of dental ceramic as affected by different types of lasers and gamma radiations

    Science.gov (United States)

    Badr, Yehia; El'Khoudary, M. A.; Annan, Iman

    2004-05-01

    Dental ceramic:Duceram porcelain(Ducera,Dental-Gesellschaft mbH, FrankFurt, Germany) low fusing dental porcelain was subjected in this investigation to different types of laser radiations: a) Nd:YAG laser pulses o 8 ns, 200mJ/pulse for 5&10 minutes b) Tsonamy 70 fs laser pulses for 1 & 5 minutes c)193 nm Excimer laser pulses 6 &13 mJ/pulse for 5 & 10 minutes and finally d) 0.1, 0.3, 0.5 and 1 MRad of Gamma radiations using 10 samples for each type of radiation. Knoop hardness values of test samples were measured using a knoop hardness tester(KHN-Ernst Leitz Wetzlar Germany)showing increased hardness values for all test irradiated samples as compared with the control. Highest hardness value were recorded for Excimer laser 13 mJ/pulse-10 minutes(670kg/mm2 as compared with 410kg/mm2 for the control. On the other hand, the highest value for the transverse strength was obtained for Excimer laser 3.8mJ/pulse-10 minutes). To account for the structural changes occurring due to laser irradiations and leading to the detected here improvement in the mechanical properties we used several techniques which are known to be sensitive to any structural changes such as: x-ray diffraction, SE-Microscopy, FTIR & Raman spectroscopy. Our observations showed series of variations indicating good accordance in the introduced here results. A reasonable interpretation is given here for the effects and variations observed in our measurements and spectra as a result of both Gamma and Laser irradiation. Finally, the given here results indicated that Laser irradiation can be used as a powerful tool for improving the hardness and transverse strength of dental ceramic.

  19. Photomultiplier circuit including means for rapidly reducing the sensitivity thereof. [and protection from radiation damage

    Science.gov (United States)

    Mcclenahan, J. O. (Inventor)

    1974-01-01

    A simple, reliable and inexpensive control circuit is described for rapidly reducing the bias voltage across one or more of the dynode stages of a photomultiplier, to substantially decrease its sensitivity to incoming light at those times where excess light intensity might damage the tube. The control circuit comprises a switching device, such as a silicon controlled rectifier (SCR), coupled between a pair of the electrodes in the tube, preferably the cathode and first dynode, or the first and second dynodes, the switching device operating in response to a trigger pulse applied to its gate to short circuit the two electrodes. To insure the desired reduction in sensitivity, two switching stages, the devices be employed between two of the electrode stages, the devices being operated simultaneously to short circuit both stages.