WorldWideScience

Sample records for cell radiation resistance

  1. High Radiation Resistance IMM Solar Cell

    Science.gov (United States)

    Pan, Noren

    2015-01-01

    Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

  2. Phytosphingosine can overcome resistance to ionizing radiation in ionizing radiation-resistant cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Moon Taek; Choi, Jung A; Kim, Min Jeong; Bae, Sang Woo; Kang, Chang Mo; Cho, Chul Koo; Lee, Yun Sil; Lee, Su Jae [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Kang, Seong Man [Graduate School of Biotechnology, Korea University, Seoul (Korea, Republic of); Chung, Hee Yong [College of Medicine, Hanyang University, Seoul (Korea, Republic of)

    2004-07-01

    Although the majority of cancer cells are killed by inonizing radiation, certain types show resistance to it. We previously reported that phytosphingosine also induces apoptotic cell death in caspase dependent pathway in human cancer cells. In the present study, we examined whether phytosphingosine could overcome radiation resistance in the variant Jurkat clones. We first selected radiation-resistant Jurkat clones and examined cross-responsiveness of the clones between radiation and phytosphingosine. Treatment with phytosphingosine significantly did not affect apoptosis in all the clones, indicating that there seemed to be cross-resistance between radiation and phytosphingosine. Nevertheless, combined treatment of phytosphingosine with radiation synergistically enhanced killing of radiation-resistant cells, compared to radiation or phytosphingosine alone. The pan-caspase inhibitor z-VAD-fmk did not completely inhibit the synergistic cell killing induced by combined treatment of ionizing radiation and phytosphingosine. These results demonstrated that apoptosis induced by combined treatment of radiation and phytosphingosine in radiation-resistant cells was associated with caspase independent pathway. We also found that apoptotic cell death induced by combined treatment of ionizing radiation and phytosphingosine correlated to the increases of ROS. The enhancement of ROS generation induced the loss of mitochondria transmembrane potential. In conclusion, ROS generation in combined treatment of phytosphingosine with radiation significantly induced the translocation of AIF to nucleus from mitochondria, suggesting a potential clinical application of combination treatment of radiation and phytosphingosine to radiation-resistant cancer cells.

  3. Tumourigenicity and radiation resistance of mesenchymal stem cells

    DEFF Research Database (Denmark)

    D'Andrea, Filippo Peder; Horsman, Michael Robert; Kassem, Moustapha;

    2012-01-01

    Background. Cancer stem cells are believed to be more radiation resistant than differentiated tumour cells of the same origin. It is not known, however, whether normal nontransformed adult stem cells share the same radioresistance as their cancerous counterpart. Material and methods....... Nontumourigenic (TERT4) and tumourigenic (TRET20) cell lines, from an immortalised mesenchymal stem cell line, were grown in culture prior to irradiation and gene expression analysis. Radiation resistance was measured using a clonogenic assay. Differences in gene expression between the two cell lines, both under...... intercellular matrix. These results also indicate that cancer stem cells are more radiation resistant than stem cells of the same origin....

  4. Simple method to demonstrate radiation-inducible radiation resistance in microbial cells.

    OpenAIRE

    Tan, S. T.; Maxcy, R. B.

    1986-01-01

    A simple method for detection of radiation-inducible radiation resistance was developed by irradiating aliquots (0.01 ml) of cell suspension on agar plates. Part of each experimental plate was subjected to an induction treatment, and subsequent radiation resistance was compared with that of untreated cells on the same plate. The UV radiation resistance of a Micrococcus sp. was increased approximately 1.6 times by an induction treatment. This simple procedure of irradiating cells in a "fixed" ...

  5. Simple method to demonstrate radiation-inducible radiation resistance in microbial cells

    International Nuclear Information System (INIS)

    A simple method for detection of radiation-inducible radiation resistance was developed by irradiating aliquots (0.01 ml) of cell suspension on agar plates. Part of each experimental plate was subjected to an induction treatment, and subsequent radiation resistance was compared with that of untreated cells on the same plate. The UV radiation resistance of a Micrococcus sp. was increased approximately 1.6 times by an induction treatment. This simple procedure of irradiating cells in a fixed position on agar avoided washing, centrifugation, and cell enumeration required in traditional methods

  6. Radiation resistance of solar cells for space application, 1

    International Nuclear Information System (INIS)

    A 50-μm thick ultrathin silicon solar cell and a 280-μm thick high performance AlGaAs/GaAs solar cell with high radiation resistance have been recently developed by National Space Development Agency of Japan (NASDA). In order to study the radiation resistance of these cells, a joint research was carried out between Japan Atomic Energy Research Institute (JAERI) and NASDA from 1984 through 1987. In this research, the irradiation method of electron beams, the effects of the irradiation conditions on the deterioration of solar cells by electron beams, and the annealing effects of the radiation damage in solar cells were investigated. This paper is the first one of a series of reports of the joint research. In this paper, the space radiation environment which artificial satellites will encounter, the solar cells used, and the experimental methods are described. In addition to these, the results of the study on the irradiation procedure of electron beams are reported. In the study of the irradiation method of electron beams, three methods, that is, the fixed irradiation method, the moving irradiation method, and the spot irradiation method were examined. In the fixed irradiation method and moving one, stationary solar cells and solar cells moving by conveyer were irradiated by scanning electron beams, respectively. On the other hand, in the spot irradiation method, stationary solar cells were irradiated by non-scanning steady electron beams. It was concluded that the fixed irradiation method was the most proper method. In addition to this, in this study, some pieces of information were obtained with respect to the changes in the electrical characteristics of solar cells caused by the irradiation of electron beams. (author) 52 refs

  7. Autophagy contributes to resistance of tumor cells to ionizing radiation

    International Nuclear Information System (INIS)

    Background and purpose: Autophagy signaling is a novel important target to improve anticancer therapy. To study the role of autophagy on resistance of tumor cells to ionizing radiation (IR), breast cancer cell lines differing in their intrinsic radiosensitivity were used. Materials and methods: Breast cancer cell lines MDA-MB-231 and HBL-100 were examined with respect to clonogenic cell survival and induction of autophagy after radiation exposure and pharmacological interference of the autophagic process. As marker for autophagy the appearance of LC3-I and LC3-II proteins was analyzed by SDS-PAGE and Western blotting. Formation of autophagic vacuoles was monitored by immunofluorescence staining of LC3. Results: LC3-I and LC3-II formation differs markedly in radioresistant MDA-MB-231 versus radiosensitive HBL-100 cells. Western blot analyses of LC3-II/LC3-I ratio indicated marked induction of autophagy by IR in radioresistant MDA-MB-231 cells, but not in radiosensitive HBL-100 cells. Indirect immunofluorescence analysis of LC3-II positive vacuoles confirmed this differential effect. Pre-treatment with 3-methyladenine (3-MA) antagonized IR-induced autophagy. Likewise, pretreatment of radioresistant MDA-231 cells with autophagy inhibitors 3-MA or chloroquine (CQ) significantly reduced clonogenic survival of irradiated cells. Conclusion: Our data clearly indicate that radioresistant breast tumor cells show a strong post-irradiation induction of autophagy, which thus serves as a protective and pro-survival mechanism in radioresistance.

  8. Sphingosine enhances apoptosis of radiation-resistant prostate cancer cells.

    Science.gov (United States)

    Nava, V E; Cuvillier, O; Edsall, L C; Kimura, K; Milstien, S; Gelmann, E P; Spiegel, S

    2000-08-15

    Ceramide has been implicated as an important component of radiation-induced apoptosis of human prostate cancer cells. We examined the role of the sphingolipid metabolites--ceramide, sphingosine, and sphingosine-1-phosphate--in susceptibility to radiation-induced apoptosis in prostate cancer cell lines with different sensitivities to gamma-irradiation. Exposure of radiation-sensitive TSU-Pr1 cells to 8-Gy irradiation led to a sustained increase in ceramide, beginning after 12 h of treatment and increasing to 2.5- to 3-fold within 48 h. Moreover, irradiation of TSU-Pr1 cells also produced a marked and rapid 50% decrease in the activity of sphingosine kinase, the enzyme that phosphorylates sphingosine to form sphingosine-1-phosphate. In contrast, the radiation-insensitive cell line, LNCaP, had sustained sphingosine kinase activity and did not produce elevated ceramide levels on 8-Gy irradiation. Although LNCaP cells are highly resistant to gamma-irradiation-induced apoptosis, they are sensitive to the death-inducing effects of tumor necrosis factor alpha, which also increases ceramide levels in these cells (K. Kimura et al., Cancer Res., 59: 1606-1614, 1999). Moreover, we found that although irradiation alone did not increase sphingosine levels in LNCaP cells, tumor necrosis factor alpha plus irradiation induced significantly higher sphingosine levels and markedly reduced intracellular levels of sphingosine-1-phosphate. The elevation of sphingosine levels either by exogenous sphingosine or by treatment with the sphingosine kinase inhibitor N,N-dimethylsphingosine induced apoptosis and also sensitized LNCaP cells to gamma-irradiation-induced apoptosis. Our data suggest that the relative levels of sphingolipid metabolites may play a role in determining the radiosensitivity of prostate cancer cells, and that the enhancement of ceramide and sphingosine generation could be of therapeutic value. PMID:10969794

  9. Radiation- and chemoinduced multidrug resistance in colon carcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Bartkowiak, Detlef; Stempfhuber, Michael; Wiegel, Thomas; Bottke, Dirk [Dept. of Radiotherapy and Radiooncology, Univ. of Ulm (Germany)

    2009-12-15

    Background and purpose: radiation can induce multidrug resistance (MDR) and thus interfere with simultaneous or subsequent chemotherapy. In SW620 colon carcinoma cells, the interrelation of various biological endpoints of MDR was analyzed and the potential of fractionated irradiation and chemoselection to evoke MDR was compared. Material and methods: to induce/select an MDR phenotype, SW620 were exposed to either 27 Gy in 1.8-Gy daily fractions or to 50% inhibiting concentrations of doxorubicin or cisplatin, given over 6-15 weeks. Expression of genes involved in MDR, including glutathione metabolism, was determined by semiquantitative RT-PCR (reverse transcription-polymerase chain reaction). Efflux was analyzed by flow cytometry after staining with rhodamine-123 or 5-chloromethyl fluorescein diacetate. Apoptosis was monitored after pulse exposure to doxorubicin or cisplatin. Colony-forming assays were performed under continuous drug exposure. Results: a pronounced gene induction was found in MRP2 after cisplatin selection and up to 3 weeks after radiation. LRP was activated only shortly after radiation. Radiation enhanced rhodamine-123 efflux to a similar extent as short-term chemoselection but not as much as long-term drug exposure. Drug-induced apoptosis was slightly delayed in preirradiated cells. Clonogenic growth in the progeny of irradiated cells was less sensitive to cisplatin but not to doxorubicin. Conclusion: fractionated radiation can induce an MDR phenotype in SW620. However, long-term drug exposure establishes a more efficient selection. Various endpoints are not fully concordant regarding the extent of MDR. Posttranscriptional modifications, pleiotropic regulation, and alternative pathways may cause these discrepancies. (orig.)

  10. Radiation induction of drug resistance in RIF-1: Correlation of tumor and cell culture results

    International Nuclear Information System (INIS)

    The RIF-1 tumor line contains cells that are resistant to various anti-neoplastic drugs, including 5-fluorouracil (5FU), methotrexate (MTX), adriamycin (ADR), and etoposide (VP16). The frequency of these drug-resistant cells is increased after irradiation. The frequency of drug-resistant cells and the magnitude of radiation-induced drug resistance are different in cell culture than in tumors. The dose-response and expression time relationships for radiation induction of drug resistance observed in RIF-1 tumors are unusual.We hypothesize that at high radiation doses in vivo, we are selecting for cells that are both drug resistant and radiation resistant due to microenvironmental factors, whereas at low radiation doses in vivo and all radiation doses in vitro, we are observing true mutants. These studies indicate that there can be significant differences in drug-resistance frequencies between tumors and their cell lines of origin, and that radiation induction of drug resistance depends significantly on whether the induction is done in tumors or in cell culture. These results imply that theories about the induction of drug resistance that are based on cell culture studies may be inapplicable to the induction of drug resistance in tumors

  11. Radiation-resistant B-1 cells: A possible initiating cells of neoplastic transformation.

    Science.gov (United States)

    Guimarães-Cunha, Caroline Ferreira; Alvares-Saraiva, Anuska Marcelino; de Souza Apostolico, Juliana; Popi, Ana Flavia

    2016-07-01

    The role of B-1 cells in the hyperproliferative hematologic disease has been described. Several reports bring evidences that B-1 cells are the main cell population in the chronic lymphatic leukemia. It is also described that these cells have an important involvement in the lupus erythematous systemic. The murine model used to investigate both disease models is NZB/NZW. Data from literature point that mutation in micro-RNA 15a and 16 are the responsible for the B-1 hyperplasia in these mice. Interestingly, it was demonstrated that NZB/NZW B-1 cells are radioresistant, contrariwise to observe in other mouse lineage derived B-1 cells and B-2 cells. However, some reports bring evidences that a small percentage of B-1 cells in healthy mice are also able to survive to irradiation. Herein, we aim to investigate the malignant potential of ionizing-radiation resistant B-1 cells in vitro. Our main goal is to establish a model that mimics the neoplastic transformation originate to a damage exposure of DNA, and not only related to intrinsic mutations. Data shown here demonstrated that radiation-resistant B-1 cells were able to survive long periods in culture. Further, these cells show proliferation index increase in relation to non-irradiated B-1 cells. In addition, radiation resistant B-1 cells showed hyperploid, morphologic alterations, increased induction of apoptosis after anti-IgM stimulation. Based on these results, we could suggest that radiation resistant B-1 cells showed some modifications in that could be related to induction of malignant potential. PMID:26898918

  12. Materials That Enhance Efficiency and Radiation Resistance of Solar Cells

    Science.gov (United States)

    Sun, Xiadong; Wang, Haorong

    2012-01-01

    A thin layer (approximately 10 microns) of a novel "transparent" fluorescent material is applied to existing solar cells or modules to effectively block and convert UV light, or other lower solar response waveband of solar radiation, to visible or IR light that can be more efficiently used by solar cells for additional photocurrent. Meanwhile, the layer of fluorescent coating material remains fully "transparent" to the visible and IR waveband of solar radiation, resulting in a net gain of solar cell efficiency. This innovation alters the effective solar spectral power distribution to which an existing cell gets exposed, and matches the maximum photovoltaic (PV) response of existing cells. By shifting a low PV response waveband (e.g., UV) of solar radiation to a high PV response waveband (e.g. Vis-Near IR) with novel fluorescent materials that are transparent to other solar-cell sensitive wavebands, electrical output from solar cells will be enhanced. This approach enhances the efficiency of solar cells by converting UV and high-energy particles in space that would otherwise be wasted to visible/IR light. This innovation is a generic technique that can be readily implemented to significantly increase efficiencies of both space and terrestrial solar cells, without incurring much cost, thus bringing a broad base of economical, social, and environmental benefits. The key to this approach is that the "fluorescent" material must be very efficient, and cannot block or attenuate the "desirable" and unconverted" waveband of solar radiation (e.g. Vis-NIR) from reaching the cells. Some nano-phosphors and novel organometallic complex materials have been identified that enhance the energy efficiency on some state-of-the-art commercial silicon and thin-film-based solar cells by over 6%.

  13. Radiation induction of drug resistance in RIF-1 tumors and tumor cells

    International Nuclear Information System (INIS)

    The RIF-1 tumor cell line contains a small number of cells (1-20 per 10(6) cells) that are resistant to various single antineoplastic drugs, including 5-fluorouracil (5FU), methotrexate (MTX), and adriamycin (ADR). For 5FU the frequency of drug resistance is lower for tumor-derived cells than for cells from cell culture; for MTX the reverse is true, and for ADR there is no difference. In vitro irradiation at 5 Gy significantly increased the frequency of drug-resistant cells for 5FU, MTX, and ADR. In vivo irradiation at 3 Gy significantly increased the frequency of drug-resistant cells for 5FU and MTX, but not for ADR. The absolute risk for in vitro induction of MTX, 5FU, and ADR resistance, and for in vivo induction of 5FU resistance, was 1-3 per 10(6) cells per Gy; but the absolute risk for in vivo induction of MTX resistance was 54 per 10(6) cells per Gy. The frequency of drug-resistant cells among individual untreated tumors was highly variable; among individual irradiated tumors the frequency of drug-resistant cells was significantly less variable. These studies provide supporting data for models of the development of tumor drug resistance, and imply that some of the drug resistance seen when chemotherapy follows radiotherapy may be due to radiation-induced drug resistance

  14. Resistance of colorectal cancer cells to radiation and 5-FU is associated with MELK expression

    International Nuclear Information System (INIS)

    Highlights: → MELK expression significantly increased when the cells are exposed to radiation or 5-FU. → Suppression of MELK caused cell cycle changes and decrease in proliferation. → Radiation or 5-FU treatment after MELK suppression by siRNA induced growth inhibition. -- Abstract: It was reported that the local recurrence would be caused by cancer stem cells acquiring chemo- and radio-resistance. Recently, one of the potential therapeutic targets for colorectal and other cancers has been identified, which is maternal embryonic leucine zipper kinase (MELK). MELK is known as an embryonic and neural stem cell marker, and associated with the cell survival, cell proliferation, and apoptosis. In this study, SNU-503, which is a rectal cancer cell line, was treated with radiation or 5-fluorouracil (5-FU), and elevation of the MELK expression level was observed. Furthermore, the cell line was pre-treated with small interfering RNA (siRNA) against MELK mRNA before treatment of radiation or 5-FU and its effects on cell cycle and proliferation were observed. We demonstrated that knockdown of MELK reduced the proliferation of cells with radiation or 5-FU treatment. In addition, MELK suppression caused changes in cell cycle. In conclusion, MELK could be associated with increased resistance of colorectal cancer cells against radiation and 5-FU.

  15. Breast cancers radiation-resistance: key role of the cancer stem cells marker CD24

    International Nuclear Information System (INIS)

    This work focuses on the characterization of radiation-resistant breast cancer cells, responsible for relapse after radiotherapy. The 'Cancer Stem Cells' (CSC) theory describes a radiation-resistant cellular sub-population, with enhanced capacity to induce tumors and proliferate. In this work, we show that only the CSC marker CD24-/low defines a radiation resistant cell population, able to transmit the 'memory' of irradiation, expressed as long term genomic instability in the progeny of irradiated cells. We show that CD24 is not only a marker, but is an actor of radiation-response. So, CD24 expression controls cell proliferation in vitro and in vivo, and ROS level before and after irradiation. As a result, CD24-/low cells display enhanced radiation-resistance and genomic stability. For the first time, our results attribute a role to CD24-/low CSCs in the transmission of genomic instability. Moreover, by providing informations on tumor intrinsic radiation-sensitivity, CD24- marker could help to design new radiotherapy protocols. (author)

  16. Radiation resistance of InP solar cells under light illumination

    International Nuclear Information System (INIS)

    The demonstration of superior radiation resistance of InP solar cells during solar cell operation is reported. High-energy electron irradiation effects on InP n+-p junction solar cells under light illumination are compared with those under dark conditions. The InP solar cells under light illumination are found to have less degradation in solar cell properties. This is explained by minority-carrier injection enhanced annealing of radiation-induced defects, analyzed using deep level transient spectroscopy, in the p-InP layer

  17. Endogenous superoxide dismutase and catalase activities and radiation resistance in mouse cell lines

    International Nuclear Information System (INIS)

    The relationship between the endogenous cytoplasmic levels of the enzymes superoxide dismutase and catalase and the inhibition of cell proliferation by γ-radiation has been studied in 11 mouse cell lines. The resistance of these mouse cell lines to radiation was found to vary by over 25-fold. No correlation was found between the cytoplasmic level of CuZn-superoxide dismutase or catalase and the resistance to radiation as measured by extrapolation number (EN), quasi-threshold dose (Dsub(q)), or Dsub(o). None of the cell lines had detectable cytoplasmic Mn-superoxide dismutase. The apparent Ksub(i) of potassium cyanide for mouse CuZn-superoxide dismutase was determined (Ksub(i) = 6.5 μmol dm-3). (author)

  18. Acquired Tumor Cell Radiation Resistance at the Treatment Site Is Mediated Through Radiation-Orchestrated Intercellular Communication

    Energy Technology Data Exchange (ETDEWEB)

    Aravindan, Natarajan, E-mail: naravind@ouhsc.edu [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Aravindan, Sheeja; Pandian, Vijayabaskar; Khan, Faizan H.; Ramraj, Satish Kumar; Natt, Praveen [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Natarajan, Mohan [Department of Pathology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas (United States)

    2014-03-01

    Purpose: Radiation resistance induced in cancer cells that survive after radiation therapy (RT) could be associated with increased radiation protection, limiting the therapeutic benefit of radiation. Herein we investigated the sequential mechanistic molecular orchestration involved in radiation-induced radiation protection in tumor cells. Results: Radiation, both in the low-dose irradiation (LDIR) range (10, 50, or 100 cGy) or at a higher, challenge dose IR (CDIR), 4 Gy, induced dose-dependent and sustained NFκB-DNA binding activity. However, a robust and consistent increase was seen in CDIR-induced NFκB activity, decreased DNA fragmentation, apoptosis, and cytotoxicity and attenuation of CDIR-inhibited clonal expansion when the cells were primed with LDIR prior to challenge dose. Furthermore, NFκB manipulation studies with small interfering RNA (siRNA) silencing or p50/p65 overexpression unveiled the influence of LDIR-activated NFκB in regulating CDIR-induced DNA fragmentation and apoptosis. LDIR significantly increased the transactivation/translation of the radiation-responsive factors tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), cMYC, and SOD2. Coculture experiments exhibit LDIR-influenced radiation protection and increases in cellular expression, secretion, and activation of radiation-responsive molecules in bystander cells. Individual gene-silencing approach with siRNAs coupled with coculture studies showed the influence of LDIR-modulated TNF-α, IL-1α, cMYC, and SOD2 in induced radiation protection in bystander cells. NFκB inhibition/overexpression studies coupled with coculture experiments demonstrated that TNF-α, IL-1α, cMYC, and SOD2 are selectively regulated by LDIR-induced NFκB. Conclusions: Together, these data strongly suggest that scattered LDIR-induced NFκB-dependent TNF-α, IL-1α, cMYC, and SOD2 mediate radiation protection to the subsequent challenge dose in tumor cells.

  19. Acquired Tumor Cell Radiation Resistance at the Treatment Site Is Mediated Through Radiation-Orchestrated Intercellular Communication

    International Nuclear Information System (INIS)

    Purpose: Radiation resistance induced in cancer cells that survive after radiation therapy (RT) could be associated with increased radiation protection, limiting the therapeutic benefit of radiation. Herein we investigated the sequential mechanistic molecular orchestration involved in radiation-induced radiation protection in tumor cells. Results: Radiation, both in the low-dose irradiation (LDIR) range (10, 50, or 100 cGy) or at a higher, challenge dose IR (CDIR), 4 Gy, induced dose-dependent and sustained NFκB-DNA binding activity. However, a robust and consistent increase was seen in CDIR-induced NFκB activity, decreased DNA fragmentation, apoptosis, and cytotoxicity and attenuation of CDIR-inhibited clonal expansion when the cells were primed with LDIR prior to challenge dose. Furthermore, NFκB manipulation studies with small interfering RNA (siRNA) silencing or p50/p65 overexpression unveiled the influence of LDIR-activated NFκB in regulating CDIR-induced DNA fragmentation and apoptosis. LDIR significantly increased the transactivation/translation of the radiation-responsive factors tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), cMYC, and SOD2. Coculture experiments exhibit LDIR-influenced radiation protection and increases in cellular expression, secretion, and activation of radiation-responsive molecules in bystander cells. Individual gene-silencing approach with siRNAs coupled with coculture studies showed the influence of LDIR-modulated TNF-α, IL-1α, cMYC, and SOD2 in induced radiation protection in bystander cells. NFκB inhibition/overexpression studies coupled with coculture experiments demonstrated that TNF-α, IL-1α, cMYC, and SOD2 are selectively regulated by LDIR-induced NFκB. Conclusions: Together, these data strongly suggest that scattered LDIR-induced NFκB-dependent TNF-α, IL-1α, cMYC, and SOD2 mediate radiation protection to the subsequent challenge dose in tumor cells

  20. Cancer stem cell overexpression of nicotinamide N-methyltransferase enhances cellular radiation resistance

    DEFF Research Database (Denmark)

    D’Andrea, Filippo P.; Safwat, Akmal; Kassem, Moustapha; Gautier, Laurent; Overgaard, Jens; Horsman, Michael R.

    2011-01-01

    BackgroundCancer stem cells are thought to be a radioresistant population and may be the seeds for recurrence after radiotherapy. Using tumorigenic clones of retroviral immortalized human mesenchymal stem cell with small differences in their phenotype, we investigated possible genetic expression...... analysis found the genes involved in cancer, proliferation, DNA repair and cell death. ConclusionsThe higher radiation resistance in clone CE8 is likely due to NNMT overexpression. The higher levels of NNMT could affect the cellular damage resistance through depletion of the accessible amounts of...... nicotinamide, which is a known inhibitor of cellular DNA repair mechanisms....

  1. Dexamethasone-induced enhancement of resistance to ionizing radiation and chemotherapeutic agents in human tumor cells

    International Nuclear Information System (INIS)

    Background: Dexamethasone-induced changes in radioresistance have previously been observed by several authors. Here, we examined effects of dexamethasone on resistance to ionizing radiation in 10 additional human cell lines and strains, and on resistance to carboplatin and paclitaxel in 13 fresh tumor samples. Material and Methods: Eight human carcinoma cell lines, a glioblastoma cell line and a strain of normal human diploid fibroblasts were arbitrarily chosen for these in-vitro studies. Effects on radiosensitivity were assessed using a conventional colony formation assay. Effects on resistance to the drugs were investigated prospectively (ATP cell viability assay) using 13 fresh tumor samples from consecutive patients operated for ovarian cancer within the context of a Swiss nation-wide randomized prospective clinical trial (SAKK 45/94). Results: Dexamethasone promoted proliferation of 1 of the cell lines without affecting radiosensitivity, while it completely inhibited proliferation of another cell line (effects on radiosensitivity could thus not be examined). Furthermore, dexamethasone induced enhanced radioresistance in 1 of the 8 carcinoma cell lines examined. In the glioblastoma cell line, there was no effect on growth or radioresistance, nor in the fibroblasts. Treatment with dexamethasone enhanced resistance of the malignant cells to carboplatin in 4 of the 13 fresh tumor samples examined, while no enhancement in resistance to paclitaxel was observed. Conclusions: In agreement with previous reports, we found that dexamethasone may induce radioresistance in human carcinoma cells. Including the published data from the literature, dexamethasone induced enhancement in radioresistance in 4 of 12 carcinoma cell lines (33%), but not in 3 glioblastoma cell lines, nor in 3 fibroblast strains. Dexamethasone also induced enhanced resistance to carboplatin with a similar probability in fresh samples of ovarian cancer evaluated prospectively (in 4 of 13 samples; 31

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

    Science.gov (United States)

    Haro, Kurtis John

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

  3. Coordinate regulation of proteins associated with radiation resistance in cultured insect cells

    International Nuclear Information System (INIS)

    Cultured TN-368 lepidopteran insect cells exhibit a pronounced resistance to the lethal effects of a variety of physical agents, including X rays and 254 nm UV light, as well as a large number of chemicals. The resistance to ionizing radiation has previously been associated with an inducible process which is not expressed in unirradiated cells or cells receiving less than some minimal amount of radiation necessary for activating the process. The studies in this paper were initiated in an attempt to identify and characterize the inducible proteins associated with the marked radiation resistance of the TN-368 cells. Cells were exposed to doses of 0, 25, 64 or 350 Gy of 137Cs γ rays and incubated either for 3 h in medium containing [35S]methionine or for 2 h without labeling. Labeled cells were separated into nuclear and cytoplasmic fractions and proteins were analyzed on two-dimensional polyacrylamide gels. Unlabeled cells were used to isolate total RNA which was translated in vitro in a rabbit reticulocyte lysate system with 35S label. These translation products were also analyzed by two-dimensional electrophoresis. Gamma irradiation of the TN-368 cells resulted in the de novo synthesis of several proteins as well as the complete inhibition of others. The number of such proteins identified was 19. These proteins ranged in size from 18-73 kDa, with a pI distribution of 4.7 to 6.1. In addition to the unique proteins, a large number of other proteins were also either up- or down-regulated. These observations were made in both nuclear and cytoplasmic fractions as well as in the translation products of RNA produced after irradiation. These studies indicate that RNA and protein synthesis in lepidopteran cells are coordinately regulated in response to ionizing radiation and may participate in the pronounced radioresistance of the TN-368 cells. 15 refs., 3 figs., 1 tab

  4. RAD18 mediates resistance to ionizing radiation in human glioma cells

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Chen; Wang, Hongwei; Cheng, Hongbin; Li, Jianhua; Wang, Zhi, E-mail: drzwang@gmail.com; Yue, Wu, E-mail: drwuyue@gmail.com

    2014-02-28

    Highlights: • RAD18 is an important mediator of the IR-induced resistance in glioma cell lines. • RAD18 overexpression confers resistance to IR-mediated apoptosis. • The elevated expression of RAD18 is associated with recurrent GBM who underwent IR therapy. - Abstract: Radioresistance remains a major challenge in the treatment of glioblastoma multiforme (GBM). RAD18 a central regulator of translesion DNA synthesis (TLS), has been shown to play an important role in regulating genomic stability and DNA damage response. In the present study, we investigate the relationship between RAD18 and resistance to ionizing radiation (IR) and examined the expression levels of RAD18 in primary and recurrent GBM specimens. Our results showed that RAD18 is an important mediator of the IR-induced resistance in GBM. The expression level of RAD18 in glioma cells correlates with their resistance to IR. Ectopic expression of RAD18 in RAD18-low A172 glioma cells confers significant resistance to IR treatment. Conversely, depletion of endogenous RAD18 in RAD18-high glioma cells sensitized these cells to IR treatment. Moreover, RAD18 overexpression confers resistance to IR-mediated apoptosis in RAD18-low A172 glioma cells, whereas cells deficient in RAD18 exhibit increased apoptosis induced by IR. Furthermore, knockdown of RAD18 in RAD18-high glioma cells disrupts HR-mediated repair, resulting in increased accumulation of DSB. In addition, clinical data indicated that RAD18 was significantly higher in recurrent GBM samples that were exposed to IR compared with the corresponding primary GBM samples. Collectively, our findings reveal that RAD18 may serve as a key mediator of the IR response and may function as a potential target for circumventing IR resistance in human GBM.

  5. Cytoplasmic superoxide dismutase and catalase activity and resistance to radiation lethality in murine tumor cells

    International Nuclear Information System (INIS)

    Reduced species of molecular oxygen are produced by the interaction of ionizing radiation with aqueous solutions containing molecular oxygen. The enzymes catalase and superoxide dismutase (SOD) are thought to function in vivo as scavengers of metabolically produced peroxide and superoxide respectively. SOD has been shown to protect against the lethal effects of ionizing radiation in vitro and in vivo. The authors have investigated the relationship between the cytosolic SOD catalase content and the sensitivity to radiation lethality of a number of murine cell lines (402AX, EL-4, MB-2T3, MB-4, MEL, P-815, SAI, SP-2, and SV-3T3). K/sub i/(CN-) for murine Cu-Zn-SOD was determined to be 6.8 x 10-6 M. No cytosolic Mn-SOD activity was found in any of the cell lines studied. No correlation was found between the cytosolic Cu-Zn-SOD or cytosolic catalase activity and the resistance to radiation lethality or the murine cell lines studied

  6. Biological improvement of radiation resistance

    Energy Technology Data Exchange (ETDEWEB)

    Chun, K. J.; Lee, Y. K.; Kim, J. S.; Kim, J. K.; Lee, S. J

    2000-08-01

    To investigate the mechanisms of gene action related to the radiation resistance in microorganisms could be essentially helpful for the development of radiation protectants and hormeric effects of low dose radiation. This book described isolation of radiation-resistant microorganisms, induction of radiation-resistant and functionally improved mutants by gamma-ray radiation, cloning and analysis of the radiation resistance related genes and analysis of the expressed proteins of the radiation resistant related genes.

  7. Biological improvement of radiation resistance

    International Nuclear Information System (INIS)

    To investigate the mechanisms of gene action related to the radiation resistance in microorganisms could be essentially helpful for the development of radiation protectants and hormeric effects of low dose radiation. This book described isolation of radiation-resistant microorganisms, induction of radiation-resistant and functionally improved mutants by gamma-ray radiation, cloning and analysis of the radiation resistance related genes and analysis of the expressed proteins of the radiation resistant related genes

  8. Targeting head and neck cancer stem cells to overcome resistance to photon and carbon ion radiation.

    Science.gov (United States)

    Bertrand, Gérald; Maalouf, Mira; Boivin, Antony; Battiston-Montagne, Priscillia; Beuve, Michael; Levy, Antonin; Jalade, Patrice; Fournier, Claudia; Ardail, Dominique; Magné, Nicolas; Alphonse, Gersende; Rodriguez-Lafrasse, Claire

    2014-02-01

    Although promising new radiation therapy techniques such as hadrontherapy are currently being evaluated in the treatment of head and neck malignancies, local control of head and neck squamous cell carcinoma (HNSCC) remains low. Here, we investigated the involvement of cancer stem-like cells (CSCs) in a radioresistant HNSCC cell line (SQ20B). Stem-like cells SQ20B/SidePopulation(SP)/CD44(+)/ALDH(high) were more resistant to both photon and carbon ion irradiation compared with non-CSCs. This was confirmed by a BrdU labeling experiment, which suggests that CSCs were able to proliferate and to induce tumorigenicity after irradiation. SQ20B/SP/CD44(+)/ALDH(high) were capable of an extended G2/M arrest phase in response to photon or carbon ion irradiation compared with non-CSCs. Moreover, our data strongly suggest that resistance of CSCs may result from an imbalance between exacerbated self-renewal and proliferative capacities and the decrease in apoptotic cell death triggering. In order to modulate these processes, two targeted pharmacological strategies were tested. Firstly, UCN-01, a checkpoint kinase (Chk1) inhibitor, induced the relapse of G2/M arrest and radiosensitization of SQ20B-CSCs. Secondly, all-trans retinoic acid (ATRA) resulted in an inhibition of ALDH activity, and induction of the differentiation and radiosensitization of SQ20B/SP/CD44(+)/ALDH(high) cells. The combination of ATRA and UCN-01 treatments with irradiation drastically decreased the surviving fraction at 2Gy of SQ20B-CSCs from 0.85 to 0.38 after photon irradiation, and from 0.45 to 0.21 in response to carbon ions. Taken together, our results suggest that the combination of UCN-01 and ATRA represent a promising pharmacological-targeted strategy that significantly sensitizes CSCs to photon or carbon ion radiation. PMID:23955575

  9. Characterization and radiation response of a heat-resistant variant of V79 cells

    International Nuclear Information System (INIS)

    A thermoresistant variant of the established cell line V79-S171-W1 was isolated after treatment with nitrosoguanidine and repeated heat treatments at 42.6 to 43 degrees C, and showed an enhanced ability to survive at 42.6, 43.5, and 44.5 degrees C. The rates of inactivation of the normal and heat-resistant lines differed by approximately a factor of 2 over this temperature range. This level of thermoresistance was stable for the first 80 doublings, but was lost by 120 doublings. This may have been due to a reversion to the normal V79 line since there was no continuous selection pressure and the thermoresistant variant, which was designated at HR7, had a longer average doubling time. Transient thermotolerance was induced in both the V79 and HR7 cells by a 10-min exposure to 44.5 degrees C. After 3 hr incubation at 37 degrees C, both cell lines had an identical sensitivity to further exposure to 44.5 degrees C. Thus the long-term thermoresistance of the HR7 cells may be due to a permanent induction of a low level of thermotolerance. The (ionizing) radiation survival curves and the ability to repair sublethal radiation damage were identical for the thermoresistant variant and the parent cell line

  10. Characterization and radiation response of a heat-resistant variant of V79 cells

    International Nuclear Information System (INIS)

    A thermoresistant variant of the established cell line V79-S171-W1 was isolated after treatment with nitrosoguanidine and repeated heat treatments at 42.6 to 430C, and showed an enhanced ability to survive at 42.6, 43.5, and44.50C. The rates of inactivation of the normal and heat-resistant lines differed by approximately a factor of 2 over this temperature range. This level of thermoresistance was stable for the first 80 doublings, but was lost by 120 doublings. This may have been due to a reversion to the normal V79 line since there was no continuous selection pressure and the thermoresistant variant, which was designated at HR7, had a longer average doubling time. Transient thermotolerance was induced in both the V79 and HR7 cells by a 10-min expsure to 44.50C. After 3 hr incubation at 370C, both cell lines had an identical sensitivity to further exposure to 44.50C. Thus the long-term thermoresistance of the HR7 cells may be due to a permanent induction of a low level of thermotolerance. The (ionizing) radiation survival curves and the ability to repair sublethal radiation damage were identical for the thermoresistance variant and the parent cell line

  11. Improved radiation resistant properties of electron irradiated c-Si solar cells

    Science.gov (United States)

    Ali, Khuram; Khan, Sohail A.; MatJafri, M. Z.

    2016-08-01

    This work investigates the radiation tolerance of c-Si solar cells under electron energy of 9 MeV with fluence of 5.09×1016 cm-2. The solar cells were fabricated and characterized before and after electron irradiation through current-voltage (I-V), capacitance-voltage (C-V), and frequency dependent conductance (Gp) measurements. The results revealed that all the output parameters such as short circuit current (Isc), open circuit voltage (Voc), series resistance (Rs), and efficiency (η) were degraded after electron irradiation. Capacitance-Voltage measurements show that there is a slight decrease in the base carrier concentration (ND), while a small increase in depletion layer width (WD) was due to an increase in the base carrier concentration. Enhancements in the density of interface states (Nss), and trap time constant (τ) have been observed after electron irradiation. The results has revealed that back surface field (BSF) solar cell with front surface passivation (FSP) presented lowest efficiency degradation ratio of 11.3% as compared to 15.3% of the solar cell without FSP. The subsequent annealing of irradiated Si solar cell devices revealed that the Si solar cell with FSP demonstrated high efficiency recovery ratio of 94% as compared to non-FSP solar cell.

  12. Nicotinamide and other benzamide analogs as agents for overcoming hypoxic cell radiation resistance in tumours

    International Nuclear Information System (INIS)

    Oxygen deficient hypoxic cells, which are resistant to sparsely ionising radiation, have now been identified in most animal and some human solid tumours and will influence the response of those tumours to radiation treatment. This hypoxia can be either chronic, arising from an oxygen diffusion limitation, or acute, resulting from transient stoppages in microregional blood flow. Extensive experimental studies, especially in the last decade, have shown that nicotinamide and structurally related analogs can effectively sensitize murine tumours to both single and fractionated radiation treatments and that they do so in preference to the effects seen in mouse normal tissues. The earliest studies suggested that this enhancement of radiation damage was the result of an inhibition of the repair mechanisms. However, recent studies in mouse tumours have shown that these drugs prevent transient cessations in blood flow, thus inhibiting the development of acute hypoxia. This novel discovery led to the suggestion that the potential role of these agents as radiosensitizers would be when combined with treatments that overcame chronic hypoxia. The combined nicotinamide with hyperthermia proved that the enhancement of radiation damage by both agents together was greater than that seen with each agent alone. Similar results were later seen for nicotinamide combined with a perfluorochemical emulsion, carbogen breathing, and pentoxifylline, and in all these studies the effects in tumours were always greater than those seen in appropriate normal tissues. Of all the analogs, it is nicotinamide itself which has been the most extensively studied as a radiosensitizer in vivo and the one that shows the greatest effect in animal tumours. It is also an agent that has been well established clinically, with daily doses of up to 6 g, associated with a low incidence of side effects. This human dose is equivalent to 100-200 mg/kg in mice and such doses will maximally sensitize murine tumours to

  13. Up-regulation of DNA-dependent protein kinase correlates with radiation resistance in oral squamous cell carcinoma

    International Nuclear Information System (INIS)

    DNA-PK is a nuclear protein with serine/threonine kinase activity and forms a complex consisting of the DNA-PKcs and a heterodimer of Ku70 and Ku80 proteins. Recent laboratory experiments have demonstrated that the DNA-PK complex formation is one of the major pathways by which mammalian cells respond to DNA double-strand breaks induced by ionizing radiation. In this study, we evaluated the relationship between expression levels of DNA-PKcs, Ku70 and Ku80 proteins and radiation sensitivity in oral squamous cell carcinoma (OSCC) cell lines and in OSCC patients treated with preoperative radiation therapy. The OSCC cell lines greatly differed in their response to irradiation, as assessed by a standard colony formation assay. However, the expression levels of the DNA-PK complex proteins were all similar, and there was no association between the magnitude of their expression and the tumor radiation sensitivity. Expression of DNA-PK complex proteins increased after radiation treatment, and the increased values correlated with the tumor radiation resistance. Expression of DNA-PKcs and Ku70 after irradiation was increased in the surviving cells of OSCC tissues irradiated preoperatively. These results suggest that up-regulation of DNA-PK complex protein, especially DNA-PKcs, after radiation treatment correlates to radiation resistance. DNA-PKcs might be a molecular target for a novel radiation sensitization therapy of OSCC. (author)

  14. Analysis of radiation resistance of InGaP/GaAs dual-junction thin-film space solar cell

    International Nuclear Information System (INIS)

    Thin-film III-V multi-junction solar cells can realize the advantages of being high-efficiency and light-weight, as such these cells meets the requirement for higher specific power and lower stowage volume solar panels. Here we report the development results of an InGaP/GaAs thin-film dual-junction (TF2J) solar cell. In this paper, we study the radiation resistance of the TF2J cells with efficiency of 20-23% under AM0.1 sun at 25degC. The cells were subjected to proton irradiation with an energy range of 100keV-10MeV. The results were compared with the radiation resistance of a conventional InGaP/GaAs/Ge triple-junction (3J) cell. In the proton energy range of 200-400keV, radiation resistance of the TF2J cell is superior to that of the 3J cell. Particularly, the 1sc of the TF2J cell is significantly higher than that of the 3J cell after exposure to 380keV protons, which results in higher remaining factor of Pmax for the TF2J cell. In additions, Voc of the cells after the irradiations are almost equivalent, even though the TF2J cell is a dual-junction structure. The higher 1sc of the TF2J cell after irradiation is due to higher radiation resistance of the GaAs subcell according to the comparison of the spectral response. (author)

  15. ABCG2 regulates self-renewal and stem cell marker expression but not tumorigenicity or radiation resistance of glioma cells

    Science.gov (United States)

    Wee, Boyoung; Pietras, Alexander; Ozawa, Tatsuya; Bazzoli, Elena; Podlaha, Ondrej; Antczak, Christophe; Westermark, Bengt; Nelander, Sven; Uhrbom, Lene; Forsberg-Nilsson, Karin; Djaballah, Hakim; Michor, Franziska; Holland, Eric C.

    2016-01-01

    Glioma cells with stem cell traits are thought to be responsible for tumor maintenance and therapeutic failure. Such cells can be enriched based on their inherent drug efflux capability mediated by the ABC transporter ABCG2 using the side population assay, and their characteristics include increased self-renewal, high stem cell marker expression and high tumorigenic capacity in vivo. Here, we show that ABCG2 can actively drive expression of stem cell markers and self-renewal in glioma cells. Stem cell markers and self-renewal was enriched in cells with high ABCG2 activity, and could be specifically inhibited by pharmacological and genetic ABCG2 inhibition. Importantly, despite regulating these key characteristics of stem-like tumor cells, ABCG2 activity did not affect radiation resistance or tumorigenicity in vivo. ABCG2 effects were Notch-independent and mediated by diverse mechanisms including the transcription factor Mef. Our data demonstrate that characteristics of tumor stem cells are separable, and highlight ABCG2 as a potential driver of glioma stemness. PMID:27456282

  16. Fractionated irradiation of H69 small-cell lung cancer cells causes stable radiation and drug resistance with increased MRP1, MRP2, and topoisomerase IIα expression

    International Nuclear Information System (INIS)

    Purpose: After standard treatment with chemotherapy and radiotherapy, small-cell lung cancer (SCLC) often develops resistance to both treatments. Our aims were to establish if fractionated radiation treatment alone would induce radiation and drug resistance in the H69 SCLC cell line, and to determine the mechanisms of resistance. Methods and Materials: H69 SCLC cells were treated with fractionated X-rays to an accumulated dose of 37.5 Gy over 8 months to produce the H69/R38 subline. Drug and radiation resistance was determined using the MTT (3,-4,5 dimethylthiazol-2,5 diphenyltetrazolium bromide) cell viability assay. Protein expression was analyzed by Western blot. Results: The H69/R38 subline was resistant to radiation (2.0 ± 0.2-fold, p<0.0001), cisplatin (14 ± 7-fold, p < 0.001), daunorubicin (6 ± 3-fold, p<0.05), and navelbine (1.7 ± 0.15-fold, p<0.02). This was associated with increased expression of the multidrug resistance-associated proteins, MRP1 and MRP2, and topoisomerase IIα and decreased expression of glutathione-S-transferase π (GSTπ) and bcl-2 and decreased cisplatin accumulation. Treatment with 4 Gy of X-rays produced a 66% decrease in MRP2 in the H69 cells with no change in the H69/R38 cells. This treatment also caused a 5-fold increase in topoisomerase IIα in the H69/R38 cells compared with a 1.5-fold increase in the H69 cells. Conclusions: Fractionated radiation alone can lead to the development of stable radiation and drug resistance and an altered response to radiation in SCLC cells

  17. Radiation response of drug-resistant variants of a human breast cancer cell line: The effect of glutathione depletion

    International Nuclear Information System (INIS)

    Two drug-resistant variants of the human breast cancer cell line MCF-7 have been shown previously to exhibit radiation resistance associated with an increase in the size of the shoulder on the radiation survival curve. In the present study, glutathione (GSH) depletion was achieved by exposure of cells to buthionine sulfoximine (BSO) with, in some cases, additional treatment with dimethyl fumarate. Levels of GSH in the adriamycin-resistant subline MCF-7 ADRR are initially lower than in the other two sublines and are depleted to a greater extent by exposure to BSO. Wild-type MCF-7 cells are not sensitized by GSH depletion when irradiated under aerated conditions but are sensitized under hypoxic conditions to an extent which is related to the level of GSH depletion. In contrast both the drug-resistant sublines (MCF-7 ADRR and the melphalan-resistant line MCF-7 MLNR) are radiosensitized by GSH depletion under both aerated and hypoxic conditions. It is hypothesized that in the case of the MCF-7 ADRR cell line, which expresses high levels of the GSH-associated redox enzyme systems, GSH-S-transferase and GSH-peroxidase (GSH-Px), radiosensitization results when GSH-Px is inhibited in GSH-depleted cells. The reasons for radiosensitization of aerated MCF-7 MLNR cells cannot be explained on this basis, however, and other factors are being examined

  18. Radiation resistance of thin-film solar cells for space photovoltaic power

    Science.gov (United States)

    Woodyard, James R.; Landis, Geoffrey A.

    1991-01-01

    Copper indium diselenide, cadmium telluride, and amorphous silicon alloy solar cells have achieved noteworthy performance and are currently being studied for space power applications. Cadmium sulfide cells had been the subject of much effort but are no longer considered for space applications. A review is presented of what is known about the radiation degradation of thin film solar cells in space. Experimental cadmium telluride and amorphous silicon alloy cells are reviewed. Damage mechanisms and radiation induced defect generation and passivation in the amorphous silicon alloy cell are discussed in detail due to the greater amount of experimental data available.

  19. Resistance to infection with Eimeria vermiformis in mouse radiation chimeras is determined by donor bone-marrow cells

    International Nuclear Information System (INIS)

    The course of infection with Eimeria vermiformis was determined in BALB/b, BALB/c, and C57BL/10ScSn (B10) mice and in radiation chimeras prepared from the H-2-compatible BALB/b and B10 mice. The BALB strains, irrespective of H-2 haplotype, were resistant, the B10 mice were susceptible, and in the chimeras infection was characterized by the genotype of the donated bone-marrow cells and not by the phenotype of the recipient. Thus, the genetic control of relative resistance or susceptibility to infection with this parasite is expressed through bone-marrow-derived cells

  20. Autophagy inhibition plays the synergetic killing roles with radiation in the multi-drug resistant SKVCR ovarian cancer cells

    International Nuclear Information System (INIS)

    Autophagy has attracted attentions as a novel mechanism for tumor development. In this study Human ovarian carcinoma cell line SKOV3 and multidrug-resistant phenotype SKVCR cells were used and the roles of autophagy in radiation-induced cell death were analyzed. Cell viability was examined by colony formation and cell counting kit-8 (CCK-8) assay, 3MA and ZVAD were used to block autophagy and apoptosis, respectively. Quantitative real-time PCR was used to detect mRNA level and Western blot was used to detect protein expression, monodansylcadaverine (MDC) staining and flow cytometery were used for autophagy, apoptosis and cell cycle dynamics, respectively. (1) The radiosensitivity exhibited differently in SKOV3 and SKVCR cells (SKOV3: D0=3.37, SKVCR: D0= 4.18); compared with SKOV3 the constitutive expression of MAPLC3 in SKVCR was higher, but no change of Caspase-3 and cleaved Caspase-3. (2) The ionizing radiation (IR)- induced apoptosis and autophagy were significant in both cells (P<0.05); inhibition of apoptosis with ZVAD showed no impact on survival of SKOV3 and SKVCR cells after radiation, while inhibition of autophagy significantly decreased viability in SKVCR cells, for SKVO3 cells only low level of radiation (2 Gy and 4 Gy) could decrease the viability(P<0.05). (3) ZVAD inhibited apoptosis and autophagy in both cells, 3MA inhibit apoptosis in SKOV3, and promote apoptosis in SKVCR, together with inhibition of autophagy. (4) G2/M arrest was induced by radiation in both cells; the accumulation of G2/M was more significant in SKOV3, 3MA attenuated the radiation-induced S phase delay in SKVCR. IR-induced autophagy provides a self-protective mechanism against radiotherapy in SKVCR cells, the use of autophagy inhibitor, 3MA, increases the killing effects of radiation by inhibiting autophagy and radiation- induced S phase delay, also by the increase of apoptosis, which suggests a better therapeutic strategy in drug- resistant SKVCR ovarian cancer cells

  1. MET inhibition overcomes radiation resistance of glioblastoma stem-like cells.

    Science.gov (United States)

    De Bacco, Francesca; D'Ambrosio, Antonio; Casanova, Elena; Orzan, Francesca; Neggia, Roberta; Albano, Raffaella; Verginelli, Federica; Cominelli, Manuela; Poliani, Pietro L; Luraghi, Paolo; Reato, Gigliola; Pellegatta, Serena; Finocchiaro, Gaetano; Perera, Timothy; Garibaldi, Elisabetta; Gabriele, Pietro; Comoglio, Paolo M; Boccaccio, Carla

    2016-01-01

    Glioblastoma (GBM) contains stem-like cells (GSCs) known to be resistant to ionizing radiation and thus responsible for therapeutic failure and rapidly lethal tumor recurrence. It is known that GSC radioresistance relies on efficient activation of the DNA damage response, but the mechanisms linking this response with the stem status are still unclear. Here, we show that the MET receptor kinase, a functional marker of GSCs, is specifically expressed in a subset of radioresistant GSCs and overexpressed in human GBM recurring after radiotherapy. We elucidate that MET promotes GSC radioresistance through a novel mechanism, relying on AKT activity and leading to (i) sustained activation of Aurora kinase A, ATM kinase, and the downstream effectors of DNA repair, and (ii) phosphorylation and cytoplasmic retention of p21, which is associated with anti-apoptotic functions. We show that MET pharmacological inhibition causes DNA damage accumulation in irradiated GSCs and their depletion in vitro and in GBMs generated by GSC xenotransplantation. Preclinical evidence is thus provided that MET inhibitors can radiosensitize tumors and convert GSC-positive selection, induced by radiotherapy, into GSC eradication. PMID:27138567

  2. Mitochondria-targeted superoxide dismutase (SOD2) regulates radiation resistance and radiation stress response in HeLa cells

    International Nuclear Information System (INIS)

    Reactive oxygen species (ROS) act as a mediator of ionizing radiation-induced cellular damage. Previous studies have indicated that MnSOD (SOD2) plays a critical role in protection against ionizing radiation in mammalian cells. In this study, we constructed two types of stable HeLa cell lines overexpressing SOD2, HeLa S3/SOD2 and T-REx HeLa/SOD2, to elucidate the mechanisms underlying the protection against radiation by SOD2. SOD2 overexpression in mitochondria enhanced the survival of HeLa S3 and T-REx HeLa cells following γ-irradiation. The levels of γH2AX significantly decreased in HeLa S3/SOD2 and T-REx HeLa/SOD2 cells compared with those in the control cells. MitoSoxTM Red assays showed that both lines of SOD2-expressing cells showed suppression of the superoxide generation in mitochondria. Furthermore, flow cytometry with a fluorescent probe (2',7'-dichlorofluorescein) revealed that the cellular levels of ROS increased in HeLa S3 cells during post-irradiation incubation, but the increase was markedly attenuated in HeLa S3/SOD2 cells. DNA microarray analysis revealed that, of 47,000 probe sets analyzed, 117 and 166 probes showed more than 2-fold changes after 5.5 Gy of γ-irradiation in control and HeLa S3/SOD2 cells, respectively. Pathway analysis revealed different expression profiles in irradiated control cells and irradiated SOD2-overexpressing cells. These results indicate that SOD2 protects HeLa cells against cellular effects of γ-rays through suppressing oxidative stress in irradiated cells caused by ROS generated in the mitochondria and through regulating the expression of genes which play a critical role in protection against ionizing radiation. (author)

  3. Role of tumour initiating cells in the radiation resistance of osteosarcoma

    International Nuclear Information System (INIS)

    In the present study we confirm that mouse osteosarcoma (MOS) cells lines possess a subset of cells with Tumour Initiating Cells (TICs) properties. We found that isolated TICs are not inherently radioresistant compared to non-TICs. On the other hand, we found that the fraction of TICs correlates well with the radiosensitivity of MOS cell lines measured using clonogenic cell survival assay. We conclude from our study that the TICs contribute to the tumour radiation response due to their interaction with their tumour surrounding environmental (niche).

  4. Resistance to infection with Eimeria vermiformis in mouse radiation chimeras is determined by donor bone-marrow cells.

    OpenAIRE

    Joysey, H S; Wakelin, D; Rose, M E

    1988-01-01

    The course of infection with Eimeria vermiformis was determined in BALB/b, BALB/c, and C57BL/10ScSn (B10) mice and in radiation chimeras prepared from the H-2-compatible BALB/b and B10 mice. The BALB strains, irrespective of H-2 haplotype, were resistant, the B10 mice were susceptible, and in the chimeras infection was characterized by the genotype of the donated bone-marrow cells and not by the phenotype of the recipient. Thus, the genetic control of relative resistance or susceptibility to ...

  5. A study of radiation sensitivity and drug-resistance by DNA methylation in human tumor cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Il Lae; Kim, In Gyu; Kim, Kug Chan

    2009-12-15

    It has recently been known that functional loss of tumor suppressive genes may com from DNA methylation on the chromosome. This kind of tumorigenesis has became one of the major field related to the epigenetics, whose study would be an important fundamental approach in cancer therapy market. In this study, we firstly selected two radiation-resistant mutant H460 cells, which doesn't show any significant cytotoxic effect compared to their parental wild type H460. We found that the two mutants has decreased level of PTEN, whose expression has known to be related to the cell differentiation and growth. We also found that the level of PTEN was greatly different in two lung adenocarcinoma, H460 and A549, in which more radiation-resistant A549 cells showed the decreased PTEN expression. This difference in PTEN expression between two cells was resulted from their different methylation on 5 CpG islands. We expect to know more profoundly through investigating the PTEN-related downstream genes.

  6. A study of radiation sensitivity and drug-resistance by DNA methylation in human tumor cell lines

    International Nuclear Information System (INIS)

    It has recently been known that functional loss of tumor suppressive genes may com from DNA methylation on the chromosome. This kind of tumorigenesis has became one of the major field related to the epigenetics, whose study would be an important fundamental approach in cancer therapy market. In this study, we firstly selected two radiation-resistant mutant H460 cells, which doesn't show any significant cytotoxic effect compared to their parental wild type H460. We found that the two mutants has decreased level of PTEN, whose expression has known to be related to the cell differentiation and growth. We also found that the level of PTEN was greatly different in two lung adenocarcinoma, H460 and A549, in which more radiation-resistant A549 cells showed the decreased PTEN expression. This difference in PTEN expression between two cells was resulted from their different methylation on 5 CpG islands. We expect to know more profoundly through investigating the PTEN-related downstream genes

  7. A simple external resistance heating diamond anvil cell and its application for synchrotron radiation x-ray diffraction

    International Nuclear Information System (INIS)

    A simple external heating assemblage allowing diamond anvil cell experiments at pressures up to 34 GPa and temperatures up to 653 K was constructed. This cell can be connected to the synchrotron radiation conveniently. The design and construction of this cell are fully described, as well as its applications for x-ray diffraction. Heating is carried out by using an external-heating system, which is made of NiCr resistance wire, and the temperature was measured by a NiCr-NiSi or PtRh-Pt thermocouple. We showed the performance of the new system by introducing the phase transition study of cinnabar (α-HgS) and thermal equation of state study of almandine at high pressure and temperature with this cell.

  8. CpG-ODN 7909 increases radiation sensitivity of radiation-resistant human lung adenocarcinoma cell line by overexpression of Toll-like receptor 9.

    Science.gov (United States)

    Yan, Li; Xu, Guoxiong; Qiao, Tiankui; Chen, Wei; Yuan, Sujuan; Li, Xuan

    2013-09-01

    Radioresistance is one of the main reasons for the failure of radiotherapy in lung cancer. The aim of this study was to establish a radiation-resistant lung cancer cell line, to evaluate whether CpG oligodeoxyribonucleotide (CpG-ODN) 7909 could increase its radiosensitivity and to explore the relevant mechanisms. The radioresistant cell line, referred to as R-A549, was generated by reduplicative fractionated irradiation from the human lung adenocarcinoma cell line A549. The radioresistance of R-A549 cells were confirmed by the Cell Counting Kit-8 (CCK-8), cell viability assay, and clonogenic assay. Cell growth kinetics, morphological feature, and radiosensitivity were compared between the original A549 cells and R-A549 cells treated with or without CpG-ODN 7909 or radiation. To further explore the potential mechanisms of radiosensitivity, the cell cycle distributions and the expression of Toll-like receptor 9 (TLR-9) were examined by Western blot and flow cytometry. The R-A549 cell line was generated and its radioresistance was further confirmed. CpG-ODN 7909 was found to increase much more radiosensitivity of R-A549 cells under combined treatments with CpG-ODN 7909 and radiation compared with its control group without any treatments. They presented their respective D0 1.33 ± 0.20 Gy versus 1.76 ± 0.25 Gy with N 3.44 ± 1.01 versus 4.96 ± 0.32. Further, there was a larger cell population of R-A549 cells under combined treatment in the G2/M phase compared with the control group after treatment with CpG-ODN7909 or radiation alone at 24 and 48 hour. The expression level of TLR-9 in R-A549 cells was found higher than in A549 cells. These results suggested that CpG-ODN 7909 increased the radiosensitivity of R-A549 cells, which might be mediated via the upregulated TLR-9 and prolonged cell cycle arrest in the G2/M phase compared with A549 cells. PMID:23705865

  9. Stress-induced radiation resistance in yeast

    International Nuclear Information System (INIS)

    Cells have evolved biological defense mechanisms that can protect them against a variety of harmful environmental stress including ionizing radiation exposure. The authors have demonstrated that many stresses will induce radiation resistance in yeast. Recently it has become apparent that radiation resistance may be associated with the highly conserved 'stress response' mechanism that confers cellular resistance to a multitude of agents. A universal response to stress is the synthesis of a distinctive set of new proteins, although the function of many of these specific stress proteins is still unknown. One stress protein known to affect thermal tolerance in yeast is HSP104. This report has assessed involvement of HSP104 in the mechanism of radiation resistance by utilizing a yeast strain lacking HSP104 protein (a deletion mutant). It is previously demonstrated that radiation itself will induce yeast cells to develop radiation resistance and that the signal for the response is DNA damage. The nature of the DNA damage signal is important and it is reported that, per unit dose, low linear energy transfer (LET) 60Co gamma-rays induce a greater resistance response compared to high LET neutrons. Here is tested whether the dose rate also influences the signalling efficiency of a radiation inducing dose. (author). 4 refs., 2 figs

  10. SU-E-T-565: RAdiation Resistance of Cancer CElls Using GEANT4 DNA: RACE

    International Nuclear Information System (INIS)

    Purpose: The objective of the RACE project is to develop a comparison between Monte Carlo simulation using the Geant4-DNA toolkit and measurements of radiation damage on 3D melanoma and chondrosarcoma culture cells coupled with gadolinium nanoparticles. We currently expose the status of the developments regarding simulations. Methods: Monte Carlo studies are driven using the Geant4 toolkit and the Geant4-DNA extension. In order to model the geometry of a cell population, the opensource CPOP++ program is being developed for the geometrical representation of 3D cell populations including a specific cell mesh coupled with a multi-agent system. Each cell includes cytoplasm and nucleus. The correct modeling of the cell population has been validated with confocal microscopy images of spheroids. The Geant4 Livermore physics models are used to simulate the interactions of a 250 keV X-ray beam and the production of secondaries from gadolinium nanoparticles supposed to be fixed on the cell membranes. Geant4-DNA processes are used to simulate the interactions of charged particles with the cells. An atomistic description of the DNA molecule, from PDB (Protein Data Bank) files, is provided by the so-called PDB4DNA Geant4 user application we developed to score energy depositions in DNA base pairs and sugar-phosphate groups. Results: At the microscopic level, our simulations enable assessing microscopic energy distribution in each cell compartment of a realistic 3D cell population. Dose enhancement factors due to the presence of gadolinium nanoparticles can be estimated. At the nanometer scale, direct damages on nuclear DNA are also estimated. Conclusion: We successfully simulated the impact of direct radiations on a realistic 3D cell population model compatible with microdosimetry calculations using the Geant4-DNA toolkit. Upcoming validation and the future integration of the radiochemistry module of Geant4-DNA will propose to correlate clusters of ionizations with in vitro

  11. SU-E-T-565: RAdiation Resistance of Cancer CElls Using GEANT4 DNA: RACE

    Energy Technology Data Exchange (ETDEWEB)

    Perrot, Y; Payno, H; Delage, E; Maigne, L [Clermont Universite, CNRS/IN2P3, Laboratoire de Physique Corpusculaire de Clermont-Ferrand, Aubiere (France); Incerti, S [Universite Bordeaux 1, CNRS/IN2P3, Centres d' Etudes Nucleaires de Bordeaux-Gradignan, Gradignan (France); Debiton, E; Peyrode, C; Chezal, J; Miot-Noirault, E; Degoul, F [Clermont Universite, Universite d' Auvergne, Imagerie Moleculaire et Therapie Vectorisee, INSERM U990, Centre Jean Perrin, Clermont-Ferrand (France)

    2014-06-01

    Purpose: The objective of the RACE project is to develop a comparison between Monte Carlo simulation using the Geant4-DNA toolkit and measurements of radiation damage on 3D melanoma and chondrosarcoma culture cells coupled with gadolinium nanoparticles. We currently expose the status of the developments regarding simulations. Methods: Monte Carlo studies are driven using the Geant4 toolkit and the Geant4-DNA extension. In order to model the geometry of a cell population, the opensource CPOP++ program is being developed for the geometrical representation of 3D cell populations including a specific cell mesh coupled with a multi-agent system. Each cell includes cytoplasm and nucleus. The correct modeling of the cell population has been validated with confocal microscopy images of spheroids. The Geant4 Livermore physics models are used to simulate the interactions of a 250 keV X-ray beam and the production of secondaries from gadolinium nanoparticles supposed to be fixed on the cell membranes. Geant4-DNA processes are used to simulate the interactions of charged particles with the cells. An atomistic description of the DNA molecule, from PDB (Protein Data Bank) files, is provided by the so-called PDB4DNA Geant4 user application we developed to score energy depositions in DNA base pairs and sugar-phosphate groups. Results: At the microscopic level, our simulations enable assessing microscopic energy distribution in each cell compartment of a realistic 3D cell population. Dose enhancement factors due to the presence of gadolinium nanoparticles can be estimated. At the nanometer scale, direct damages on nuclear DNA are also estimated. Conclusion: We successfully simulated the impact of direct radiations on a realistic 3D cell population model compatible with microdosimetry calculations using the Geant4-DNA toolkit. Upcoming validation and the future integration of the radiochemistry module of Geant4-DNA will propose to correlate clusters of ionizations with in vitro

  12. Radiation-resistant asporogenic bacteria

    International Nuclear Information System (INIS)

    This paper reports the biological and ecological examinations on the radiation-resistant asporogenic bacteria (mainly concerning Micrococcus radiodurans). Radiation-resistant asporogenic bacteria were isolated from the irradiated areas of the natural world as well as from the general areas and from the Rn waters in the Misasa hot spring. The acquiring of the tolerance to radiation in bacteria was also examined. In addition, the future problems of microbiological treatment with irradiation were mentioned. (Tsukamoto, Y.)

  13. Collagen I confers gamma radiation resistance

    International Nuclear Information System (INIS)

    The effect of collagen on the response of somatomammotroph tumor cells (GH3) to gamma, radiation therapy was studied in vitro. After incubating confluent GH3 cell monolayers in a serum-free, maintaining medium, either with or without collagen, the monolayers were irradiated with 137Cs, gamma radiation. Collagen reduces cell mortality via ERK1/2 activation, abolishing gamma radiation, cell death, and promotes cell invasion when acting in synergy with collagen and in association with the, MAPK/ERK1/2 signaling pathway activation. The presence of collagen in somatomammotroph tumors, confers resistance to radiation. - Highlights: ► Collagen effect on GH3 cells response to gamma radiation therapy was studied. ► Collagen ERK activation abolishes gamma radiation GH3 cell death. ► Gamma radiation promotes cell invasion and ERK activation in synergy with collagen. ► The presence of collagen in somatomammotroph tumors confers radiotherapy resistance. ► Analysis of tumor surrounding tissue before applying radiotherapy would be advisable.

  14. Adriamycin resistance, heat resistance and radiation response in Chinese hamster fibroblasts

    International Nuclear Information System (INIS)

    Previous investigators have demonstrated synergistic interaction between hyperthermia and radiation or Adriamycin (ADR), using cell lines that are sensitive to heat or ADR alone. The authors investigated the effect of heat, radiation or ADR on Chinese hamster fibroblasts (HA-1), their heat resistant variants and their ADR resistant variants. Heat for ADR resistance did not confer cross resistance to radiation. Cells resistant to heat did show cross resistance to ADR. While cells selected for ADR resistance were not cross resistant to heat, they did not exhibit drug potentiation by hyperthermia, characteristic of ADR sensitive cells. Cytofluorometric measurement showed decreased ADR uptake in both heat and ADR resistant cells. The possibility of cross resistance between heat and ADR should be considered when designing combined modality trials

  15. Radiation-resistant beamline components at LAMPF

    International Nuclear Information System (INIS)

    A variety of highly radiation-resistant beamline components have been successfully developed at LAMPF primarily for use in the target cells and beam stop area of the intense proton beamline. Design features and operating experience are reviewed for magnets, instrumentation, targets, vacuum seals, vacuum windows, collimators, and beam stops

  16. The influence of the stem cell marker ALDH and the EGFR-PI3 kinase act signaling pathway on the radiation resistance of human tumor cell lines

    International Nuclear Information System (INIS)

    Cancer is the second leading cause of death in industriated nations. Besides surgery and chemotherapy, radiotherapy (RT) is an important approach by which about 60% of patients are treated. The response of these patients to RT is very heterogenous. On the one hand, there are patients with tumors which are radiosensitive and can be cured, but on the other hand patients bear tumors which are quite resistant to radiotherapy. A Radioresistant phenotype of tumor cells causes treatment failure consequently leading to a limited response to radiotherapy. It is proposed, that radiotherapy outcome mainly depends on the potential of radiation on controlling growth, proliferation and survival of a specific population of tumor cells called cancer stem cells (CSCs) or tumor-initiating cells. Based on experimental studies so far reported it is assumed that the population of CSC varies in tumors from different entities and is relatively low compared to the tumor bulk cells in general. According to the CSC hypothesis, it might be concluded that the differential response of tumors to radiotherapy depends on CSC populations, since these supposedly slow replicating cells are able to initiate a tumor, to self renew indefinitely and to generate the differentiated progeny of a tumor. Besides the role of cancer stem cells in radiotherapy response, ionizing radiation (IR) activates the epidermal growth factor receptor (EGFR) and its downstream signaling pathways such as phosphoinositide 3-kinase (PI3K)/Akt, mitogen-activated protein kinase (MAPK) and Janus kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathways. Among these pathways, PI3K/Akt is one of the most important pathways involved in post-irradiation survival: Activation of Akt results in activation of DNA-dependent protein kinase, catalytic subunit (DNA-PKcs). DNA-PKcs is a core enzyme involved in repair of IR-induced DNA-double strand breaks (DNA-DSB) through non-homologous end joining (NHEJ). The aim of the

  17. Research of radiation-resistant microbial organisms

    International Nuclear Information System (INIS)

    Many extremophiles including radiation-resistant bacteria Deinococcus radiodurans have special characteristics such as novel enzymes and physiological active substances different from known biological materials and are being in the spotlight of biotechnology science. In this research, basic technologies for the production of new genetic resources and microbial strains by a series of studies in radiation-resistant microbial organisms were investigated and developed. Mechanisms required for radiation-resistant in Deinococcus radiodurans were partly defined by analyzing the function of dinB, pprI, recG, DRA0279, pprM, and two-component signal transduction systems. To apply genetic resource and functional materials from Deinococcus species, omics analysis in response to cadmium, construction of macroscopic biosensor, and characterization of carotenoids and chaperon protein were performed. Additionally, potential use of D. geothermalis in monosaccharide production from non-biodegradable plant materials was evaluated. Novel radiation resistant yeasts and bacteria were isolated and identified from environmental samples to obtain microbial and genomic resources. An optimal radiation mutant breeding method was set up for efficient and rapid isolation of target microbial mutants. Furthermore, an efficient ethanol producing mutant strain with high production yield and productivity was constructed using the breeding method in collaboration with Korea Research Institute of Bioscience and Biotechnology. Three Deinococcal bioindicators for radiation dosage confirmation after radiation sterilization process were developed. These results provide a comprehensive information for novel functional genetic elements, enzymes, and physiological active substances production or application. Eventually, industrial microbial cell factories based on radiation resistant microbial genomes can be developed and the technologies can be diffused to bioindustry continuously by this project

  18. Research of radiation-resistant microbial organisms

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongho; Lim, Sangyong; Joe, Minho; Park, Haejoon; Song, Hyunpa; Im, Seunghun; Kim, Haram; Kim, Whajung; Choi, Jinsu; Park, Jongchun

    2012-01-15

    Many extremophiles including radiation-resistant bacteria Deinococcus radiodurans have special characteristics such as novel enzymes and physiological active substances different from known biological materials and are being in the spotlight of biotechnology science. In this research, basic technologies for the production of new genetic resources and microbial strains by a series of studies in radiation-resistant microbial organisms were investigated and developed. Mechanisms required for radiation-resistant in Deinococcus radiodurans were partly defined by analyzing the function of dinB, pprI, recG, DRA{sub 0}279, pprM, and two-component signal transduction systems. To apply genetic resource and functional materials from Deinococcus species, omics analysis in response to cadmium, construction of macroscopic biosensor, and characterization of carotenoids and chaperon protein were performed. Additionally, potential use of D. geothermalis in monosaccharide production from non-biodegradable plant materials was evaluated. Novel radiation resistant yeasts and bacteria were isolated and identified from environmental samples to obtain microbial and genomic resources. An optimal radiation mutant breeding method was set up for efficient and rapid isolation of target microbial mutants. Furthermore, an efficient ethanol producing mutant strain with high production yield and productivity was constructed using the breeding method in collaboration with Korea Research Institute of Bioscience and Biotechnology. Three Deinococcal bioindicators for radiation dosage confirmation after radiation sterilization process were developed. These results provide a comprehensive information for novel functional genetic elements, enzymes, and physiological active substances production or application. Eventually, industrial microbial cell factories based on radiation resistant microbial genomes can be developed and the technologies can be diffused to bioindustry continuously by this project.

  19. Bacterial and archaeal resistance to ionizing radiation

    Science.gov (United States)

    Confalonieri, F.; Sommer, S.

    2011-01-01

    Organisms living in extreme environments must cope with large fluctuations of temperature, high levels of radiation and/or desiccation, conditions that can induce DNA damage ranging from base modifications to DNA double-strand breaks. The bacterium Deinococcus radiodurans is known for its resistance to extremely high doses of ionizing radiation and for its ability to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Recently, extreme ionizing radiation resistance was also generated by directed evolution of an apparently radiation-sensitive bacterial species, Escherichia coli. Radioresistant organisms are not only found among the Eubacteria but also among the Archaea that represent the third kingdom of life. They present a set of particular features that differentiate them from the Eubacteria and eukaryotes. Moreover, Archaea are often isolated from extreme environments where they live under severe conditions of temperature, pressure, pH, salts or toxic compounds that are lethal for the large majority of living organisms. Thus, Archaea offer the opportunity to understand how cells are able to cope with such harsh conditions. Among them, the halophilic archaeon Halobacterium sp and several Pyrococcus or Thermococcus species, such as Thermococcus gammatolerans, were also shown to display high level of radiation resistance. The dispersion, in the phylogenetic tree, of radioresistant prokaryotes suggests that they have independently acquired radioresistance. Different strategies were selected during evolution including several mechanisms of radiation byproduct detoxification and subtle cellular metabolism modifications to help cells recover from radiation-induced injuries, protection of proteins against oxidation, an efficient DNA repair tool box, an original pathway of DNA double-strand break repair, a condensed nucleoid that may prevent the dispersion of the DNA fragments and specific radiation-induced proteins involved in

  20. Bacterial and archaeal resistance to ionizing radiation

    International Nuclear Information System (INIS)

    Organisms living in extreme environments must cope with large fluctuations of temperature, high levels of radiation and/or desiccation, conditions that can induce DNA damage ranging from base modifications to DNA double-strand breaks. The bacterium Deinococcus radiodurans is known for its resistance to extremely high doses of ionizing radiation and for its ability to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Recently, extreme ionizing radiation resistance was also generated by directed evolution of an apparently radiation-sensitive bacterial species, Escherichia coli. Radioresistant organisms are not only found among the Eubacteria but also among the Archaea that represent the third kingdom of life. They present a set of particular features that differentiate them from the Eubacteria and eukaryotes. Moreover, Archaea are often isolated from extreme environments where they live under severe conditions of temperature, pressure, pH, salts or toxic compounds that are lethal for the large majority of living organisms. Thus, Archaea offer the opportunity to understand how cells are able to cope with such harsh conditions. Among them, the halophilic archaeon Halobacterium sp and several Pyrococcus or Thermococcus species, such as Thermococcus gammatolerans, were also shown to display high level of radiation resistance. The dispersion, in the phylogenetic tree, of radioresistant prokaryotes suggests that they have independently acquired radioresistance. Different strategies were selected during evolution including several mechanisms of radiation byproduct detoxification and subtle cellular metabolism modifications to help cells recover from radiation-induced injuries, protection of proteins against oxidation, an efficient DNA repair tool box, an original pathway of DNA double-strand break repair, a condensed nucleoid that may prevent the dispersion of the DNA fragments and specific radiation-induced proteins involved in

  1. Evidence for involvement of cytosolic thioredoxin peroxidase in the excessive resistance of Sf9 Lepidopteran insect cells against radiation-induced apoptosis.

    Science.gov (United States)

    Hambarde, Shashank; Singh, Vijaypal; Chandna, Sudhir

    2013-01-01

    Lepidopteran insect cells display 50-100 times higher radioresistance compared to human cells, and reportedly have more efficient antioxidant system that can significantly reduce radiation-induced oxidative stress and cell death. However, the antioxidant mechanisms that contribute substantially to this excessive resistance still need to be understood thoroughly. In this study, we investigated the role of thioredoxin peroxidase (TPx) in high-dose γ-radiation response of Sf9 cell line derived from Spodoptera frugiperda, the Fall armyworm. We identified a TPx orthologue (Sf-TPx) in Spodoptera system, with primarily cytosolic localization. Gamma-irradiation at 500 Gy dose significantly up-regulated Sf-TPx, while higher doses (1000 Gy-2000 Gy) had no such effect. G2/M checkpoint induced following 500 Gy was associated with transition of Sf-TPx decamer into enzymatically active dimer. Same effect was observed during G2/M block induced by 5 nM okadaic acid or 10 µM CDK1 (cycline dependent kinase-1) inhibitor roscovitine, thus indicating that radiation-induced Sf-TPx activity is mediated by CDKs. Accumulation of TPx dimer form during G2/M checkpoint might favour higher peroxidase activity facilitating efficient survival at this dose. Confirming this, higher lethal doses (1000 Gy-2000 Gy) caused significantly less accumulation of dimer form and induced dose-dependent apoptosis. A ∼50% knock-down of Sf-TPx by siRNA caused remarkable increase in radiation-induced ROS as well as caspase-3 dependent radiation-induced apoptosis, clearly implying TPx role in the radioresistance of Sf9 cells. Quite importantly, our study demonstrates for the first time that thioredoxin peroxidase contributes significantly in the radioresistance of Lepidopteran Sf9 insect cells, especially in their exemplary resistance against radiation-induced apoptosis. This is an important insight into the antioxidant mechanisms existing in this highly stress-resistant model cell system. PMID:23505474

  2. Novel Materials that Enhance Efficiency and Radiation Resistance of Solar Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Solar cell is the key device in generating electrical power for spacecrafts. It is an on-going challenge in maximizing electrical power available to spacecraft...

  3. Novel Materials that Enhance Efficiency and Radiation Resistance of Solar Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spacecrafts rely on arrays of solar cells to generate electrical power. It is an on-going challenge to maximize electrical power available to spacecraft while...

  4. Development of TRAIL Resistance by Radiation-Induced Hypermethylation of DR4 CpG Island in Recurrent Laryngeal Squamous Cell Carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Cheol [Department of Otorhinolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Department of Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Lee, Won Hyeok [Department of Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Min, Young Joo [Department of Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Cha, Hee Jeong [Department of Pathology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Han, Myung Woul [Department of Otorhinolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of); Chang, Hyo Won [Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Sun-A [Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Choi, Seung-Ho [Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Seong Who, E-mail: swhokim@gmail.com [Department of Biochemistry and Molecular Biology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Kim, Sang Yoon, E-mail: sykim3715@gmail.com [Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Biomedical Research Institute, Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2014-04-01

    Purpose: There are limited therapeutic options for patients with recurrent head and neck cancer after radiation therapy failure. To assess the use of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) as a salvage chemotherapeutic agent for recurrent cancer after radiation failure, we investigated the effect of clinically relevant cumulative irradiation on TRAIL-induced apoptosis. Methods and Materials: Using a previously established HN3 cell line from a laryngeal carcinoma patient, we generated a chronically irradiated HN3R isogenic cell line. Viability and apoptosis in HN3 and HN3R cells treated with TRAIL were analyzed with MTS and PI/annexin V-FITC assays. Western blotting and flow cytometry were used to determine the underlying mechanism of TRAIL resistance. DR4 expression was semiquantitatively scored in a tissue microarray with 107 laryngeal cancer specimens. Methylation-specific polymerase chain reaction and bisulfite sequencing for DR4 were performed for genomic DNA isolated from each cell line. Results: HN3R cells were more resistant than HN3 cells to TRAIL-induced apoptosis because of significantly reduced levels of the DR4 receptor. The DR4 staining score in 37 salvage surgical specimens after radiation failure was lower in 70 surgical specimens without radiation treatment (3.03 ± 2.75 vs 5.46 ± 3.30, respectively; P<.001). HN3R cells had a methylated DR4 CpG island that was partially demethylated by the DNA demethylating agent 5-aza-2′-deoxycytidine. Conclusion: Epigenetic silencing of the TRAIL receptor by hypermethylation of a DR4 CpG island might be an underlying mechanism for TRAIL resistance in recurrent laryngeal carcinoma treated with radiation.

  5. Development of TRAIL Resistance by Radiation-Induced Hypermethylation of DR4 CpG Island in Recurrent Laryngeal Squamous Cell Carcinoma

    International Nuclear Information System (INIS)

    Purpose: There are limited therapeutic options for patients with recurrent head and neck cancer after radiation therapy failure. To assess the use of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) as a salvage chemotherapeutic agent for recurrent cancer after radiation failure, we investigated the effect of clinically relevant cumulative irradiation on TRAIL-induced apoptosis. Methods and Materials: Using a previously established HN3 cell line from a laryngeal carcinoma patient, we generated a chronically irradiated HN3R isogenic cell line. Viability and apoptosis in HN3 and HN3R cells treated with TRAIL were analyzed with MTS and PI/annexin V-FITC assays. Western blotting and flow cytometry were used to determine the underlying mechanism of TRAIL resistance. DR4 expression was semiquantitatively scored in a tissue microarray with 107 laryngeal cancer specimens. Methylation-specific polymerase chain reaction and bisulfite sequencing for DR4 were performed for genomic DNA isolated from each cell line. Results: HN3R cells were more resistant than HN3 cells to TRAIL-induced apoptosis because of significantly reduced levels of the DR4 receptor. The DR4 staining score in 37 salvage surgical specimens after radiation failure was lower in 70 surgical specimens without radiation treatment (3.03 ± 2.75 vs 5.46 ± 3.30, respectively; P<.001). HN3R cells had a methylated DR4 CpG island that was partially demethylated by the DNA demethylating agent 5-aza-2′-deoxycytidine. Conclusion: Epigenetic silencing of the TRAIL receptor by hypermethylation of a DR4 CpG island might be an underlying mechanism for TRAIL resistance in recurrent laryngeal carcinoma treated with radiation

  6. Studies on the relationship between the radiation resistance and glutathione content of human and rodent cells after treatment with dexamethasone in vitro

    International Nuclear Information System (INIS)

    a 20 pre-treatment of human cells from normal (foetal lung) or malignant origin (glioma, lines U118 MG and U251 MG and bladder carcinoma, line EJ) with dexamethasone failed to increase their radiation resistance in vitro despite a 2-fold increase in the GSH content of a glioma cell line, U251 MG, and a small but significant increase in the GSH content of EJ bladder carcinoma cells. In contrast, there was a correlation between an increase in radiation resistance and an elevated GSH content of rodent cells (Chinese hamster lung, line V-79-379A; ovary, line CHO; rat hepatoma line HTC, and mouse neuroblastoma, line NB413A) after a similar pre-treatment. The results suggest that enhancement of radiation resistance cannot be directly ascribed to an elevated GSH content in steroid-treated cells. On the bases of these data it is unlikely that the efficacy of radiotherapy will be diminished amongst patients receiving concomitant treatment with dexamethasone. However, in vivo testing is required to confirm these findings. (author)

  7. 1.00 MeV proton radiation resistance studies of single-junction and single gap dual-junction amorphous-silicon alloy solar cells

    Science.gov (United States)

    Abdulaziz, Salman; Payson, J. S.; Li, Yang; Woodyard, James R.

    1990-01-01

    A comparative study of the radiation resistance of a-Si:H and a-SiGe:H single-junction and a-Si:H dual-junction solar cells was conducted. The cells were irradiated with 1.00-MeV protons with fluences of 1.0 x 10 to the 14th, 5.0 x 10 to the 14th and 1.0 x 10 to the 15th/sq cm and characterized using I-V and quantum efficiency measurements. The radiation resistance of single-junction cells cannot be used to explain the behavior of dual-junction cells at a fluence of 1.0 x 10 to the 15th/sq cm. The a-Si H single-junction cells degraded the least of the three cells; a-SiGe:H single-junction cells showed the largest reduction in short-circuit current, while a-Si:H dual-junction cells exhibited the largest degradation in the open-circuit voltage. The quantum efficiency of the cells degraded more in the red part of the spectrum; the bottom junction degrades first in dual-junction cells.

  8. Radiation resistence of microorganisms from radiation sterilization processing environments

    Science.gov (United States)

    Sabovljev, Svetlana A.; Žunić, Zora S.

    The radiation resistance of microorganisms was examined on the samples of dust collected from the radiation sterilization processing environments including assembly, storage, and sterilization plant areas. The isolation of radiation resistant strains was performed by irradiation with screening doses ranging from 10 to 35 kGy and test pieces containing 10 6 to 10 8 CFU in dried serum-broth, representing 100 to 5000 colonies of primary cultures of microorganisms from 7 different sites. In an examination of 16900 colonies of aerobic microorganisms from 3 hygienically controlled production sites and 4 uncontrolled ones, 30 strains of bacteria were isolated. Of those 15 were classified as genus Bacillus, 9 as Micrococcus and 6 as Sarcina. All of the 15 strains of Gram positive sporeforming aerobic rods exhibited an exponential decrease in the surviving fraction as a function of dose, indicating that the inactivation of spores of aerobic rods is a consequence of a single energy deposition into the target. All strains were found to be moderately resistant to radiation with D-6 values (dose required to reduce survival to 6 log cycles) between 18 and 26 kGy. All of the isolated Gram positive cocci showed inactivation curves having a shoulder, indicating that different processes are involved in the inactivation of these cells, e.g. accumulation of sublethal lesions, or final repair capacity of potential lethal lesions. Moderate radiation resistance was observed in 13 strains with D-6 values between 16 to 30 kGy. Two slow-growing, red pigmented strains tentatively classified as genus Micrococcus isolated from uncontrolled sites (human dwellings) were exceptionally resistant with D-6 more than 45 kGy. For hygienically controlled sites, Gram positive spereforming rods composed two thirds of the resistant microflora, while Gram positive cocci comprised one third. For hygienically uncontrolled sites this ratio was reversed. An assumption is made that one isolated strain has grown

  9. Some resistance mechanisms to ultraviolet radiation

    International Nuclear Information System (INIS)

    The cyclical exposure of bacterial cells to the ultraviolet light (UV) it has as consequence an increment in the resistance to the lethal effects of this type of radiation, increment that happens as a result of a selection process of favorable genetic mutations induced by the same UV light. With object to study the reproducibility of the genetic changes and the associate mechanisms to the resistance to UV in the bacteria Escherichia coli, was irradiated cyclically with UV light five different derived cultures of a single clone, being obtained five stumps with different resistance grades. The genetic mapping Hfr revealed that so much the mutation events like of selection that took place during the adaptation to the UV irradiation, happened of random manner, that is to say, each one of the resistant stumps it is the result of the unspecified selection of mutations arisen at random in different genes related with the repair and duplication of the DNA. (Author)

  10. Radiation resistance of nano carbon polymers

    International Nuclear Information System (INIS)

    Present article is devoted to radiation resistance of polymers containing nano carbon fillers. Therefore, the influence of ultraviolet and gamma-irradiation on structure and radiation resistance of nano carbon polymers was studied. The light resistance of polymers was studied under the light ageing conditions and the radiation resistance was studied under the static radiation ageing conditions. It is defined that injection of fillers in to the polymers and irradiation them by ultraviolet and gamma beams changes their mechanical and thermal properties and their light and radiation resistance as well.

  11. Sci—Fri AM: Mountain — 04: Label-free Raman spectroscopy of single tumour cells detects early radiation-induced glycogen synthesis associated with increased radiation resistance

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, Q; Lum, JJ [BC Cancer Agency — Vancouver Island Centre (Canada); Isabelle, M; Harder, S; Jirasek, A [Physics and Astronomy, University of Victoria (Australia); Brolo, AG [Chemistry, University of Victoria (Australia)

    2014-08-15

    Purpose: To use label-free Raman spectroscopy (RS) for early treatment monitoring of tumour cell radioresistance. Methods: Three human tumour cell lines, two radioresistant (H460, SF{sub 2} = 0.57 and MCF7, SF{sub 2} = 0.70) and one radiosensitive (LNCaP, SF{sub 2} = 0.36), were irradiated with single fractions of 2, 4, 6, 8 or 10 Gy. In additional experiments, H460 and MCF7 cells were irradiated under co-treatment with the anti-diabetic drug metformin, a known radiosensitizing agent. Treated and control cultures were analyzed with RS daily for 3 days post-treatment. Single-cell Raman spectra were acquired from 20 live cells per sample, and experiments were repeated in triplicate. The combined data sets were analyzed with principal component analysis using standard algorithms. Cells from each culture were also subjected to standard assays for viability, proliferation, cell cycle, and radiation clonogenic survival. Results: The radioresistant cells (H460, MCF7) exhibited a RS molecular radiation response signature, detectable as early as 1 day post-treatment, of which radiation-induced glycogen synthesis is a significant contributor. The radiosensitive cells (LNCaP) exhibited negligible glycogen synthesis. Co-treatment with metformin in MCF7 cells blocked glycogen synthesis, reduced viability and proliferation, and increased radiosensitivity. Conversely, metformin co-treatment in H460 cells did not produce these same effects; importantly, both radiation-induced synthesis of glycogen and radiosensitivity were unaffected. Conclusions: Label-free RS can detect early glycogen synthesis post-irradiation, a previously undocumented metabolic mechanism associated with tumour cell radioresistance that can be targeted to increase radiosensitivity. RS monitoring of intratumoral glycogen may provide new opportunities for personalized combined modality radiotherapy treatments.

  12. Radiation resistance of a hemolytic micrococcus isolated from chicken meat

    International Nuclear Information System (INIS)

    The effects of environmental factors on a highly radiation-resistant hemolytic micrococcus isolated from chicken meat were studied. NaCl tolerance and gamma radiation resistance of the cells were growth phase-related. The cells were resistant to injury from drying or freezing/thawing. Under certain conditions, cells in the frozen state required approximately 5 Mrad to inactivate 90% of the population; 0.2 Mrad injured an equivalent proportion. Survival curve of the cells heated at 600C showed a unique pattern which was in three distinct phases. Heat-stressed cells were much more sensitive to radiation inactivation than unheated cells. When suspended in fresh m-Plate Count Broth (PCB), the injured cells repaired without multiplication during incubation at 320C. The repair process in this bacterium, however, was slower compared to thermally injured organisms studied by other workers. An improved replica-plating technique, was devised for isolation of radiation-sensitive mutants of pigmented bacteria. A simple method to demonstrate radiation-inducible radiation resistance in microbial cells was developed. The new method required neither washing/centrifugation nor procedures for cell enumeration. Mutagenesis treatment of radiation-resistant micrococcal bacterium with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) followed by FPR and screening steps resulted in isolation of two radiation-sensitive mutants. The more sensitive mutant strain, designated as 702, was seven times as sensitive to gamma or UC radiation as the wild type. No apparent difference was observed between 702 and the wild type in (1) cell morphology, colonial morphology, and pigment production or (2) tolerance to NaCl, drying/storage, freezing/thawing, and heating. Sodium dodecyl sulfate treatment (for curing) of wild type did not result in isolation of a radiation-sensitive mutant

  13. Plant breeding by using radiation mutation - Selection of herbicide-resistant cell lines by using {gamma}-rays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyo Yeon [Sunchun University, Sunchun (Korea); Seo, Yong Weon [Korea University, Seoul (Korea)

    2000-04-01

    In order to develop the herbicide resistant cell lines, micro calli derived from rice anther culture and mature seed of wheat cultivars were irradiated with gamma rays. 1) The callus was dedifferentiated by 7 or 21 day pretreatment at 7 deg. C in two rice cultivars, Ilpumbyeo ad Dongjinbyeo. 2) To check the optimum concentration of herbicide, three herbicides were tested with micro calli. 3) The optimum dose of gamma ray to seeds of wheat seemed to be from 100 to 150 Gy. 4) AFLP and RAPD technique were established to develope herbicide resistant molecular marker in rice. 34 refs., 10 figs., 5 tabs. (Author)

  14. DNA replication and repair in a human melanoma cell-line resistant to ultra-violet-radiation

    International Nuclear Information System (INIS)

    The effect of ultra-violet (U.V.)-irradiation on DNA replication was studied in a U.V.-resistant, human melanoma cell-line (MM96). Semi-conservative synthesis of DNA was decreased about five-fold by a U.V.-dose of 100 ergs/mm2. The size of DNA fragments synthesized in irradiated cells at short times after U.V. was smaller than those synthesized in unirradiated cells. Elongation of these fragments occurred with time, and 6 hours after irradiation cells synthesized DNA in fragments of the same size as obtained in unirradiated cells. In this post-replication repair process, elongation appeared to involve de novo synthesis and was not inhibited by theophylline. (author)

  15. Investigation of the Stability and 1.0 MeV Proton Radiation Resistance of Commercially Produced Hydrogenated Amorphous Silicon Alloy Solar Cells

    Science.gov (United States)

    Lord, Kenneth R., II; Walters, Michael R.; Woodyard, James R.

    1994-01-01

    The radiation resistance of commercial solar cells fabricated from hydrogenated amorphous silicon alloys is reported. A number of different device structures were irradiated with 1.0 MeV protons. The cells were insensitive to proton fluences below 1E12 sq cm. The parameters of the irradiated cells were restored with annealing at 200 C. The annealing time was dependent on proton fluence. Annealing devices for one hour restores cell parameters for fluences below 1E14 sq cm fluences above 1E14 sq cm require longer annealing times. A parametric fitting model was used to characterize current mechanisms observed In dark I-V measurements. The current mechanism were explored with irradiation fluence, and voltage and light soaking times. The thermal generation current density and quality factor increased with proton fluence. Device simulation shows the degradation in cell characteristics may be explained by the reduction of the electric field in the intrinsic layer.

  16. Extreme Ionizing-Radiation-Resistant Bacterium

    Science.gov (United States)

    Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

    2013-01-01

    potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination.

  17. Effect of physiological age on radiation resistance of some bacteria that are highly radiation resistant.

    OpenAIRE

    Keller, L C; Maxcy, R. B.

    1984-01-01

    Physiological age-dependent variation in radiation resistance was studied for three bacteria that are highly radiation resistant: Micrococcus radiodurans, Micrococcus sp. isolate C-3, and Moraxella sp. isolate 4. Stationary-phase cultures of M. radiodurans and isolate C-3 were much more resistant to gamma radiation than were log-phase cultures. This pattern of relative resistance was reversed for isolate 4. Resistance of isolate 4 to UV light was also greater during log phase, although heat r...

  18. Radiation resistance due to high expression of miR-21 and G2/M checkpoint arrest in breast cancer cells

    International Nuclear Information System (INIS)

    There is evidence that the extent of the G2/M arrest following irradiation is correlated with tumour cell survival and hence therapeutic success. We studied the regulation of cellular response to radiation treatment by miR-21-mediated modulation of cell cycle progression in breast cancer cells and analysed miR-21 expression in breast cancer tissue samples with long-term follow up. The miR-21 expression levels were quantified (qRT-PCR) in a panel of 86 cases of invasive breast carcinomas in relation to metastasis free survival. The cellular radiosensitivity of human breast cancer cells after irradiation was determined comparing two cell lines (T47D and MDA-MB-361) by cell proliferation and colony forming assays. The influence of miR-21 overexpression or downregulation on cell cycle progression and G2/M checkpoint arrest after irradiation was assessed by flow cytometric analysis. The expression of miR-21 was transiently increased 8 hours after irradiation in the radioresistant T47D cells and significantly changed with lower extent in radiosensitive MDA-MB-361 cells. Anti-miR-21 treated breast cancer cells failed to exhibit the DNA damage-G2 checkpoint increase after irradiation. Apoptotic activity was significantly enhanced from 7% to 27% in T47D cells and from 18% to 30% in MDA-MB-361 cells 24 hours after 5 Gy irradiation. Additionally, we characterized expression of miR-21 in invasive breast carcinomas. In comparison to non-cancerous adjacent breast tissue, tumours samples had increased miR-21 expression that inversely correlated with the distant metastases-free survival of patients (p = 0.029). Our data indicate that miR-21 expression in breast cancer cells contributes to radiation resistance by compromising cell cycle progression. These data point to the potential of combining radiotherapy with an anti-miR-21 as a potent G2/M check point inhibitor in overcoming radiation resistance of tumours

  19. Radiation resistance due to high expression of miR-21 and G2/M checkpoint arrest in breast cancer cells

    Directory of Open Access Journals (Sweden)

    Anastasov Nataša

    2012-12-01

    Full Text Available Abstract Background There is evidence that the extent of the G2/M arrest following irradiation is correlated with tumour cell survival and hence therapeutic success. We studied the regulation of cellular response to radiation treatment by miR-21-mediated modulation of cell cycle progression in breast cancer cells and analysed miR-21 expression in breast cancer tissue samples with long-term follow up. Methods The miR-21 expression levels were quantified (qRT-PCR in a panel of 86 cases of invasive breast carcinomas in relation to metastasis free survival. The cellular radiosensitivity of human breast cancer cells after irradiation was determined comparing two cell lines (T47D and MDA-MB-361 by cell proliferation and colony forming assays. The influence of miR-21 overexpression or downregulation on cell cycle progression and G2/M checkpoint arrest after irradiation was assessed by flow cytometric analysis. Results The expression of miR-21 was transiently increased 8 hours after irradiation in the radioresistant T47D cells and significantly changed with lower extent in radiosensitive MDA-MB-361 cells. Anti-miR-21 treated breast cancer cells failed to exhibit the DNA damage-G2 checkpoint increase after irradiation. Apoptotic activity was significantly enhanced from 7% to 27% in T47D cells and from 18% to 30% in MDA-MB-361 cells 24 hours after 5 Gy irradiation. Additionally, we characterized expression of miR-21 in invasive breast carcinomas. In comparison to non-cancerous adjacent breast tissue, tumours samples had increased miR-21 expression that inversely correlated with the distant metastases-free survival of patients (p = 0.029. Conclusions Our data indicate that miR-21 expression in breast cancer cells contributes to radiation resistance by compromising cell cycle progression. These data point to the potential of combining radiotherapy with an anti-miR-21 as a potent G2/M check point inhibitor in overcoming radiation resistance of tumours.

  20. Overexpression of miRNA-21 promotes radiation-resistance of non-small cell lung cancer

    International Nuclear Information System (INIS)

    MiRNA-21 was previously reported to be up-regulated in many kinds of cancer. In the present study, we want to investigate the potential role of miRNA-21 in non-small cell lung cancer. Expression of miRNA-21 was detected in 60 non-small cell lung cancer (NSCLC) samples and adjacent histologically normal tissue using RT-qPCR, Correlation between miRNA-21 expression and clinicopathological features of NSCLC was analyzed using statistical software. The effect of miRNA-21 expression on the growth and apoptosis of A549 cells induced by irradiation was examined. miRNA-21 expression increased in non-small cell lung cancer. Expression of miRNA-21 was positively associated with lymph node metastasis, clinical stage and poor prognosis. Multivariate Cox regression analysis showed that miRNA-21 was an independent prognostic factor for patients. Down-regulation of miRNA-21 inhibited proliferation and cell cycle progress of A549 cells and sensitized cells to radiation. Decreased miRNA-21 expression promoted the apoptosis of A549 cells induced by irradiation. miRNA-21 may be considered as a potential novel target for future development of specific therapeutic interventions in NSCLC

  1. Ionizing radiation enhances therapeutic activity of mda-7/IL-24: overcoming radiation- and mda-7/IL-24-resistance in prostate cancer cells overexpressing the antiapoptotic proteins bcl-xL or bcl-2.

    Science.gov (United States)

    Su, Z-Z; Lebedeva, I V; Sarkar, D; Emdad, L; Gupta, P; Kitada, S; Dent, P; Reed, J C; Fisher, P B

    2006-04-13

    Subtraction hybridization applied to terminally differentiating human melanoma cells identified mda-7/IL-24, a cytokine belonging to the IL-10 gene superfamily. Adenoviral-mediated delivery of mda-7/IL-24 (Ad.mda-7) provokes apoptosis selectively in a wide spectrum of cancers in vitro in cell culture, in vivo in human tumor xenograft animal models and in patients with advanced carcinomas and melanomas. In human prostate cancer cells, a role for mitochondrial dysfunction and induction of reactive oxygen species in the apoptotic process has been established. Ectopic overexpression of bcl-xL and bcl-2 prevents these changes including apoptosis induction in prostate tumor cells by Ad.mda-7. We now document that this resistance to apoptosis can be reversed by treating bcl-2 family overexpressing prostate tumor cells with ionizing radiation in combination with Ad.mda-7 or purified GST-MDA-7 protein. Additionally, radiation augments apoptosis induction by mda-7/IL-24 in parental and neomycin-resistant prostate tumor cells. Radiosensitization to mda-7/IL-24 is dependent on JNK signaling, as treatment with the JNK 1/2/3 inhibitor SP600125 abolishes this effect. Considering that elevated expression of bcl-xL and bcl-2 are frequent events in prostate cancer development and progression, the present studies support the use of ionizing radiation in combination with mda-7/IL-24 as a means of augmenting the therapeutic benefit of this gene in prostate cancer, particularly in the context of tumors displaying resistance to radiation therapy owing to bcl-2 family member overexpression. PMID:16331261

  2. Development of radiation resistant organic composite materials

    International Nuclear Information System (INIS)

    Radiation resistant composite material has been developed. Stress analysis and the matrix choice were made carefully. The stress analysis reveals that the intrinsic radiation induced degradation was brought by the degradation of interlaminar shear strength. It means the preventing the degradation of interlaminar shear strength is important to develop the radiation resistant composite materials. To prevent the degradation of the interlaminar shear strength the three dimensional fabrics are used as the reinforcement and the boron free glass fibers were chosen. The possible method to develop the radiation resistant organic composites are discussed. (author)

  3. Incorporating Cancer Stem Cells in Radiation Therapy Treatment Response Modeling and the Implication in Glioblastoma Multiforme Treatment Resistance

    International Nuclear Information System (INIS)

    Purpose: To perform a preliminary exploration with a simplistic mathematical cancer stem cell (CSC) interaction model to determine whether the tumor-intrinsic heterogeneity and dynamic equilibrium between CSCs and differentiated cancer cells (DCCs) can better explain radiation therapy treatment response with a dual-compartment linear-quadratic (DLQ) model. Methods and Materials: The radiosensitivity parameters of CSCs and DCCs for cancer cell lines including glioblastoma multiforme (GBM), non–small cell lung cancer, melanoma, osteosarcoma, and prostate, cervical, and breast cancer were determined by performing robust least-square fitting using the DLQ model on published clonogenic survival data. Fitting performance was compared with the single-compartment LQ (SLQ) and universal survival curve models. The fitting results were then used in an ordinary differential equation describing the kinetics of DCCs and CSCs in response to 2- to 14.3-Gy fractionated treatments. The total dose to achieve tumor control and the fraction size that achieved the least normal biological equivalent dose were calculated. Results: Smaller cell survival fitting errors were observed using DLQ, with the exception of melanoma, which had a low α/β = 0.16 in SLQ. Ordinary differential equation simulation indicated lower normal tissue biological equivalent dose to achieve the same tumor control with a hypofractionated approach for 4 cell lines for the DLQ model, in contrast to SLQ, which favored 2 Gy per fraction for all cells except melanoma. The DLQ model indicated greater tumor radioresistance than SLQ, but the radioresistance was overcome by hypofractionation, other than the GBM cells, which responded poorly to all fractionations. Conclusion: The distinct radiosensitivity and dynamics between CSCs and DCCs in radiation therapy response could perhaps be one possible explanation for the heterogeneous intertumor response to hypofractionation and in some cases superior outcome from

  4. Incorporating Cancer Stem Cells in Radiation Therapy Treatment Response Modeling and the Implication in Glioblastoma Multiforme Treatment Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Victoria Y.; Nguyen, Dan; Pajonk, Frank; Kupelian, Patrick; Kaprealian, Tania; Selch, Michael; Low, Daniel A.; Sheng, Ke, E-mail: ksheng@mednet.ucla.edu

    2015-03-15

    Purpose: To perform a preliminary exploration with a simplistic mathematical cancer stem cell (CSC) interaction model to determine whether the tumor-intrinsic heterogeneity and dynamic equilibrium between CSCs and differentiated cancer cells (DCCs) can better explain radiation therapy treatment response with a dual-compartment linear-quadratic (DLQ) model. Methods and Materials: The radiosensitivity parameters of CSCs and DCCs for cancer cell lines including glioblastoma multiforme (GBM), non–small cell lung cancer, melanoma, osteosarcoma, and prostate, cervical, and breast cancer were determined by performing robust least-square fitting using the DLQ model on published clonogenic survival data. Fitting performance was compared with the single-compartment LQ (SLQ) and universal survival curve models. The fitting results were then used in an ordinary differential equation describing the kinetics of DCCs and CSCs in response to 2- to 14.3-Gy fractionated treatments. The total dose to achieve tumor control and the fraction size that achieved the least normal biological equivalent dose were calculated. Results: Smaller cell survival fitting errors were observed using DLQ, with the exception of melanoma, which had a low α/β = 0.16 in SLQ. Ordinary differential equation simulation indicated lower normal tissue biological equivalent dose to achieve the same tumor control with a hypofractionated approach for 4 cell lines for the DLQ model, in contrast to SLQ, which favored 2 Gy per fraction for all cells except melanoma. The DLQ model indicated greater tumor radioresistance than SLQ, but the radioresistance was overcome by hypofractionation, other than the GBM cells, which responded poorly to all fractionations. Conclusion: The distinct radiosensitivity and dynamics between CSCs and DCCs in radiation therapy response could perhaps be one possible explanation for the heterogeneous intertumor response to hypofractionation and in some cases superior outcome from

  5. miR-21 modulates resistance of HR-HPV positive cervical cancer cells to radiation through targeting LATS1

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shikai; Song, Lili, E-mail: commasll@163.com; Zhang, Liang; Zeng, Saitian; Gao, Fangyuan

    2015-04-17

    Although multiple miRNAs are found involved in radioresistance development in HR-HPV positive (+) cervical cancer, only limited studies explored the regulative mechanism of the miRNAs. miR-21 is one of the miRNAs significantly upregulated in HR-HPV (+) cervical cancer is also significantly associated with radioresistance. However, the detailed regulative network of miR-21 in radioresistance is still not clear. In this study, we confirmed that miR-21 overexpression was associated with higher level of radioresistance in HR-HPV (+) cervical cancer patients and thus decided to further explore its role. Findings of this study found miR-21 can negatively affect radiosensitivity of HR-HPV (+) cervical cancer cells and decrease radiation induced G2/M block and increase S phase accumulation. By using dual luciferase assay, we verified a binding site between miR-21 and 3′-UTR of large tumor suppressor kinase 1 (LATS1). Through direct binding, miR-21 can regulate LATS1 expression in cervical cancer cells. LATS1 overexpression can reverse miR-21 induced higher colony formation rate and also reduced miR-21 induced S phase accumulation and G2/M phase block reduction under radiation treatment. These results suggested that miR-21-LATS1 axis plays an important role in regulating radiosensitivity. - Highlights: • miR-21 is highly expressed in HR-HPV (+) radioresistant cervical cancer patients. • miR-21 can negatively affect radiosensitivity of HR-HPV (+) cervical cancer cells. • miR-21 can decrease radiation induced G2/M block and increase S phase accumulation. • miR-21 modulates radiosensitivity cervical cancer cell by directly targeting LATS1.

  6. miR-21 modulates resistance of HR-HPV positive cervical cancer cells to radiation through targeting LATS1

    International Nuclear Information System (INIS)

    Although multiple miRNAs are found involved in radioresistance development in HR-HPV positive (+) cervical cancer, only limited studies explored the regulative mechanism of the miRNAs. miR-21 is one of the miRNAs significantly upregulated in HR-HPV (+) cervical cancer is also significantly associated with radioresistance. However, the detailed regulative network of miR-21 in radioresistance is still not clear. In this study, we confirmed that miR-21 overexpression was associated with higher level of radioresistance in HR-HPV (+) cervical cancer patients and thus decided to further explore its role. Findings of this study found miR-21 can negatively affect radiosensitivity of HR-HPV (+) cervical cancer cells and decrease radiation induced G2/M block and increase S phase accumulation. By using dual luciferase assay, we verified a binding site between miR-21 and 3′-UTR of large tumor suppressor kinase 1 (LATS1). Through direct binding, miR-21 can regulate LATS1 expression in cervical cancer cells. LATS1 overexpression can reverse miR-21 induced higher colony formation rate and also reduced miR-21 induced S phase accumulation and G2/M phase block reduction under radiation treatment. These results suggested that miR-21-LATS1 axis plays an important role in regulating radiosensitivity. - Highlights: • miR-21 is highly expressed in HR-HPV (+) radioresistant cervical cancer patients. • miR-21 can negatively affect radiosensitivity of HR-HPV (+) cervical cancer cells. • miR-21 can decrease radiation induced G2/M block and increase S phase accumulation. • miR-21 modulates radiosensitivity cervical cancer cell by directly targeting LATS1

  7. Effect of radiation decontamination on drug-resistant bacteria

    International Nuclear Information System (INIS)

    More than 80% of food poisoning bacteria such as Salmonella are reported as antibiotic-resistant to at least one type antibiotic, and more than 50% as resistant to two or more. For the decontamination of food poisoning bacteria in foods, radiation resistibility on drug-resistant bacteria were investigated compared with drug-sensitive bacteria. Possibility on induction of drug-resistant mutation by radiation treatment was also investigated. For these studies, type strains of Escherichia coli S2, Salmonella enteritidis YK-2 and Staphylococcus aureus H12 were used to induce drug-resistant strains with penicillin G. From the study of radiation sensitivity on the drug-resistant strain induced from E. coli S2, D10 value was obtained to be 0.20 kGy compared with 0.25 kGy at parent strain. On S. enteritidis YK-2, D10 value was obtained to be 0.14 kGy at drug-resistant strain compared with 0.16 kGy at parent strain. D10 value was also obtained to be 0.15 kGy at drug-resistant strain compared with 0.21 kGy at parent strain of St. aureus H12. Many isolates of E. coli 157:H7 or other type of E. coli from meats such as beef were resistant to penicillin G, and looked to be no relationship on radiation resistivities between drug-resistant strains and sensitive strains. On the study of radiation sensitivity on E. coli S2 at plate agars containing antibiotics, higher survival fractions were obtained at higher doses compared with normal plate agar. The reason of higher survival fractions at higher doses on plate agar containing antibiotics should be recovery of high rate of injured cells by the relay of cell division, and drug-resistant strains by mutation are hardly induced by irradiation. (author)

  8. Radiation, micro-organisms and radiation resistance

    International Nuclear Information System (INIS)

    This paper discusses the importance of identifying lethal and mutagenic lesions induced in bacteria by ionizing radiations, and the repair of such lesions. A study of the molecular nature of radiation damage to contaminating bacteria in food and the ability of the bacteria to survive such damage is essential to an efficient food and food products irradiation programme. (UK)

  9. A stunning resistance to radiations

    International Nuclear Information System (INIS)

    The Deinococus radiodurans bacteria (DRB) can survive extreme radiation doses as high as 100 times the doses that kill other bacteria. The number of DNA breaking due to irradiation is the same as in other bacteria but DRB benefits from a very efficient DNA repairing system. This system relies on the fact that DRB owns 4 to 10 identical copies of its genome and because of this high number of copies the repair process is very likely to find a no-damaged part of the DNA in one copy to reconstitute the DNA. It appears that this process does not involve specific enzymes but enzymes that are present in any other bacteria. The efficiency of the repairing process relies on two things: first, the circular shape of the genome that avoids the spreading in the cell of the DNA breaks, and secondly, the enzymes are protected from irradiation oxidation by a high concentration in manganese and iron. (A.C.)

  10. Cell death induced by ionizing radiations in human radio-resistant tumours: in-vitro and in-vivo study of mechanisms involved in its induction by different types of radiations and pharmacological modulation

    International Nuclear Information System (INIS)

    Whereas chemo-radiotherapy protocols revealed to be very efficient when taking tumours into care, the treatment of some tumours remains very limited due to their critical location or to the weak radio-sensitivity to conventional radiations. One way to work around this problem is to use high linear energy transfer radiations or hadron therapy, in combination with radio-sensitizers. This research thesis reports the assessment of radio-sensitizer effects of different molecules on human radio-resistant cell lines and more particularly the SK-Hep1 line from a hepatocellular carcinoma. In vitro studies have been performed and then in vivo studies by using fast neutron irradiation on a mice liver sample. Observations made by optic fibre confocal microscopy and transmission electronic microscopy confirmed in vitro observations: the prevailing cell death after such an irradiation is the autophagic cell death. It shows the importance of the autophagic phenomenon induced by radiations with high linear transfer energy. This could lead to new therapeutic protocols for radio-resistant cancers

  11. Potential mechanisms involved in resistant phenotype of MCF-7 breast carcinoma cells to ionizing radiation induced apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanling [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Zhang Hong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou 730000 (China)], E-mail: zhangh@impcas.ac.cn; Li Ning [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Wang Xiaohu [Department of Radiotherapy, Gansu Tumor Hospital, Lanzhou 730050 (China); Hao Jifang [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou 730000 (China); Zhao Weiping [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou 730000 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China)

    2009-03-15

    In the present study, we investigated the mechanisms of apoptosis resistance and the roles of the phosphorylation of BRCA1, p21, the Bax/Bcl-2 protein ratio and cell cycle arrest in IR-induced apoptosis in MCF-7 cells. X-irradiation, in particular at low dose (1 Gy), but not carbon ion irradiation, had a significant antiproliferative effect on the growth of MCF-7 cells. 1 Gy X-irradiation resulted in G1 and G2 phase arrest, but 4 Gy induced a significant G1 block. In contrast, carbon ion irradiation resulted in a significant accumulation in the G2 phase. Concomitant with the phosphorylation of H2AX induced by DNA damage, carbon ion irradiation resulted in an approximately 1.9-2.8-fold increase in the phosphorylation of BRCA1 on serine residue 1524, significantly greater than that detected for X-irradiation. Carbon ion irradiation caused a dramatic increase in p21 expression and drastic decrease in Bax expression compared with X-irradiation. The data implicated that phosphorylation of BRCA1 on serine residue 1524 might, at least partially, induce p21 expression but repress Bax expression. Together, our results suggested that the phosphorylation of BRCA1 at Ser-1524 might contribute to the G2 phase arrest and might be an upstream signal involved in preventing apoptosis signal via upregulation of p21 and downregulation of the Bax/Bcl-2 ratio.

  12. Potential mechanisms involved in resistant phenotype of MCF-7 breast carcinoma cells to ionizing radiation induced apoptosis

    Science.gov (United States)

    Wang, Yan-ling; Zhang, Hong; Li, Ning; Wang, Xiao-hu; Hao, Ji-fang; Zhao, Wei-ping

    2009-03-01

    In the present study, we investigated the mechanisms of apoptosis resistance and the roles of the phosphorylation of BRCA1, p21, the Bax/Bcl-2 protein ratio and cell cycle arrest in IR-induced apoptosis in MCF-7 cells. X-irradiation, in particular at low dose (1 Gy), but not carbon ion irradiation, had a significant antiproliferative effect on the growth of MCF-7 cells. 1 Gy X-irradiation resulted in G1 and G2 phase arrest, but 4 Gy induced a significant G1 block. In contrast, carbon ion irradiation resulted in a significant accumulation in the G2 phase. Concomitant with the phosphorylation of H2AX induced by DNA damage, carbon ion irradiation resulted in an approximately 1.9-2.8-fold increase in the phosphorylation of BRCA1 on serine residue 1524, significantly greater than that detected for X-irradiation. Carbon ion irradiation caused a dramatic increase in p21 expression and drastic decrease in Bax expression compared with X-irradiation. The data implicated that phosphorylation of BRCA1 on serine residue 1524 might, at least partially, induce p21 expression but repress Bax expression. Together, our results suggested that the phosphorylation of BRCA1 at Ser-1524 might contribute to the G2 phase arrest and might be an upstream signal involved in preventing apoptosis signal via upregulation of p21 and downregulation of the Bax/Bcl-2 ratio.

  13. CERN selects Fujikura's radiation resistant fiber

    CERN Multimedia

    2007-01-01

    "Fujikura Europe Ltd. (search for Fujikura Europe) today announced that its radiation resistant singlemode optical fiber has been selected by CERN to provide communicaton links within the world's largest particle accelerator..."(2/3 page)

  14. Predicted solar cell edge radiation effects

    International Nuclear Information System (INIS)

    The Advanced Solar Cell Orbital Test (ASCOT) will test six types of solar cells in a high energy proton environment. During the design of the experiment a question was raised about the effects of proton radiation incident on the edge of the solar cells and whether edge radiation shielding was required. Historical geosynchronous data indicated that edge radiation damage is not detectable over the normal end of life solar cell degradation; however because the ASCOT radiation environment has a much higher and more energetic fluence of protons, considerably more edge damage is expected. A computer analysis of the problem was made by modeling the expected radiation damage at the cell edge and using a network model of small interconnected solar cells to predict degradation in the cell's electrical output. The model indicated that the deepest penetration of edge radiation was at the top of the cell near the junction where the protons have access to the cell through the low density cell/cover adhesive layer. The network model indicated that the cells could tolerate high fluences at their edge as long as there was high electrical resistance between the edge radiated region and the contact system on top of the cell. The predicted edge radiation related loss was less than 2% of maximum power for GaAs/Ge solar cells. As a result, no edge radiation protection was used for ASCOT

  15. A novel radiation-induced p53 mutation is not implicated in radiation resistance via a dominant-negative effect.

    Directory of Open Access Journals (Sweden)

    Yunguang Sun

    Full Text Available Understanding the mutations that confer radiation resistance is crucial to developing mechanisms to subvert this resistance. Here we describe the creation of a radiation resistant cell line and characterization of a novel p53 mutation. Treatment with 20 Gy radiation was used to induce mutations in the H460 lung cancer cell line; radiation resistance was confirmed by clonogenic assay. Limited sequencing was performed on the resistant cells created and compared to the parent cell line, leading to the identification of a novel mutation (del at the end of the DNA binding domain of p53. Levels of p53, phospho-p53, p21, total caspase 3 and cleaved caspase 3 in radiation resistant cells and the radiation susceptible (parent line were compared, all of which were found to be similar. These patterns held true after analysis of p53 overexpression in H460 cells; however, H1299 cells transfected with mutant p53 did not express p21, whereas those given WT p53 produced a significant amount, as expected. A luciferase assay demonstrated the inability of mutant p53 to bind its consensus elements. An MTS assay using H460 and H1299 cells transfected with WT or mutant p53 showed that the novel mutation did not improve cell survival. In summary, functional characterization of a radiation-induced p53 mutation in the H460 lung cancer cell line does not implicate it in the development of radiation resistance.

  16. Solar cell radiation handbook

    Science.gov (United States)

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

    1982-01-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  17. Radiation resistant modification of silicone rubber

    International Nuclear Information System (INIS)

    For the use in the light-water nuclear power generation plants, wires and cables are required to keep flame retardancy and superior resistivity against heat and radiation throughout the whole period of service. They are expected, further, to fulfill their functions even under LOCA conditions. A new technology to give flame and radiation resistancy to insulating materials for general use in the nuclear power facilities was already reported in JAERI-M 82-057. The present study aimed subsequently to provide a method to give high radiation resistancy to dimethylsilicone rubber (DMS) which is used as highly heat resistant insulating materials (thermal tolerance, 1800C). For the improvement of radiation resistancy, the effects of polymer blending were examined by blending DMS with other rubbers, e.g., ethylene-propylene diene rubber (EPDM) or tetrafluoroethylene-propylene copolymer (Copoly (TFE-P)), which show different degradation behavior each other when exposed to radiation. After detailed experimental works, it was elucidated that the blended rubbers show higher radiation resistance (150 -- 200 Mrad) than DMS. In particular when DMS-Copoly (TFE-P) blend was incorporated with a small amount of CeO2, high heat and radiation resistivity and satisfactory electrical performance were shown in the sequential tests (heat aging (2200C, 4 days) → radiation (200 Mrad) → super heated steam (1500C, 1 day)) according to IEEE standards for simulated LOCA on wire specimen. On the other hand, DMS without any modification lost its performance as insulator by the irradiation (200 Mrad). (author)

  18. Radiation and heat resistant mouldings

    International Nuclear Information System (INIS)

    Mouldings made of norbornene-ethylene-copolymers can be exposed to a radiation dose limit of 15 MGy, at an operating temperature of 373 K, without their stability values decreasing. Such mouldings can be used in medical engineering, e.g. medical instruments, container and apparatus parts; and in nuclear and radiation technology, e.g. casing parts, control devices and jacketings

  19. Resistance of CD45RA- T cells to apoptosis and functional impairment, and activation of tumor-antigen specific T cells during radiation therapy of prostate cancer.

    Science.gov (United States)

    Tabi, Zsuzsanna; Spary, Lisa K; Coleman, Sharon; Clayton, Aled; Mason, Malcolm D; Staffurth, John

    2010-07-15

    The effect of radiation therapy (RT) to the pelvis on circulating T cells was studied in prostate cancer (PCa) patients to provide a baseline for a more informed design of combination radioimmunotherapy. Peripheral blood samples taken from 12 PCa patients with locally advanced tumor before, during, and after hypofractionated RT were analyzed for T cell phenotype and function. There was significantly more loss of naive and early memory compared with more differentiated T cells during RT. The proportions of annexin-V(+) and Fas-expressing T cells were elevated in patients during RT and in PBMC irradiated in vitro ( 2-fold in the presence of an IkappaB-kinase inhibitor, indicating a protective effect via this pathway. T cell proliferation was impaired during RT with IL-2-dependent recovery post-RT. Recall T cell responses to common viral Ags, measured by IFN-gamma production, were little affected by RT. In vitro irradiation of healthy donor PBMCs resulted in a significantly increased frequency of responding T cells, due at least partly to the preferential elimination of CD45RA(+) T cells. Most importantly, antitumor CD4(+) and CD8(+) T cell responses were detectable after, but not before or during RT. The results indicate that generating tumor-specific T cell responses before RT and boosting their activity post-RT are ways likely to amplify the frequency and function of antitumor T cells, with implications for scheduling immunotherapy in PCa. PMID:20548027

  20. Radiation-resistant olefin polymer

    International Nuclear Information System (INIS)

    The invention is a method of sterilizing an article consisting essentially of polypropylene containing a minor effective proportion of a pentaerythritol phosphite ester by subjecting the article to ionizing radiation of 2-5 Mrads. The method is effective in sterilizing the article without causing any substantial degradation of the olefin polymer

  1. High resistance against ionizing radiation of some oligotrophic bacteria

    International Nuclear Information System (INIS)

    The resistance against ionizing radiation of seven cultures of oligotriphic and cutrophic bacteria was investigated in the interval 0-360 Gr. It is determine that all of lasted bacteria are dictributed into three groups according to the level of their resistance. Most resistant were: Methylobacterium organophilum, Pedodermatophilus halotolerans (LD50=270 Gr). Middle resistance shown water-born ringe-forming bacteria Flectobacillus major, Arcocella aquatica (LD50=173 and 210 Gr respectively). High sensitive were cutrophs: Pseudomonas fluorescens, Escherichia coli (LD50=43 and 38 Gr respectively. By use of X-ray microanalysis was shown that after the radiation potassium content in cell was increased and calcium content was decreased

  2. Genetic variation in resistance to ionizing radiation. [Annual report, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, F.J.

    1989-12-31

    The very reactive superoxide anion O{sub 2} is generated during cell respiration as well as during exposure to ionizing radiation. Organisms have evolved different mechanisms to protect against the deleterious effects of reduced oxygen species. The copper-zinc superoxide dismutase is a eukaryotic cytoplasmic enzyme that protects the cell by scavenging superoxide radicals and dismutating them to hydrogen peroxide and molecular oxygen: 20{sub 2}{sup {minus}} + 2H {yields} H{sub 2}O{sub 2} + O{sub 2}. SOD had been shown to protect against ionizing radiation damage to DNA, viruses, bacteria, mammalian cells, whole mice, and Drosophila. Evidence that genetic differences may affect sensitivity to ionizing radiation has been shown in Drosophila since differences have been shown to exist between strains and resistance to radiation can evolve under natural selection.

  3. Radiation resistance of anticorrosion coatings

    International Nuclear Information System (INIS)

    Experimental results are reported of a study of high-energy radiation and its effects on properties and corrosive behaviour of metals, on plastics, paints, and other coatings. The irradiation tests have been made with various paint compounds on the basis of epoxide resins, polyurethane resins, acryl/styrol dispersions, and with ethyl silicate or alkali silicate zinc dust primers. The coatings have been applied to accelerator component parts and to plate specimens (aluminium, steel) and have been irradiated with energies between 104 and 107 Gy. Very good results have been found for the polyurethane compound and the acryl/styrol dispersion coatings. (orig.)

  4. CERN selects Fujikura's radiation resistant fiber

    CERN Multimedia

    2007-01-01

    "Fujikura recently announced that its radiation resistant single mode optical fiber has been selected by CERN, the European Laboratory for Particle Physics, to provide communication links within the world's largest particle accelerator - the Large Hadron Collider (LHC) - near Geneva, Switzerland." (1/2 page)

  5. Human Genetic Marker for Resistance to Radiation and Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    DR. Howard B. Lieberman

    2001-05-11

    TO characterize the human HRDAD9 gene and evaluate its potential as a biomarker to predict susceptibility to the deleterious health effects potentially caused by exposure to radiations or chemicals present at DOE hazardous waste cleanup sites. HRAD9 is a human gene that is highly conserved throughout evolution. Related genes have been isolated from yeasts and mice, underscoring its biological significance. Most of our previous work involved characterization of the yeast gene cognate, wherein it was determined that the corresponding protein plays a significant role in promoting resistance of cells to radiations and chemicals, and in particular, controlling cell growth in response to DNA damage.

  6. Human Genetic Marker for Resistance to Radiation and Chemicals

    International Nuclear Information System (INIS)

    TO characterize the human HRDAD9 gene and evaluate its potential as a biomarker to predict susceptibility to the deleterious health effects potentially caused by exposure to radiations or chemicals present at DOE hazardous waste cleanup sites. HRAD9 is a human gene that is highly conserved throughout evolution. Related genes have been isolated from yeasts and mice, underscoring its biological significance. Most of our previous work involved characterization of the yeast gene cognate, wherein it was determined that the corresponding protein plays a significant role in promoting resistance of cells to radiations and chemicals, and in particular, controlling cell growth in response to DNA damage

  7. Effect of physiological age on radiation resistance of some bacteria that are highly radiation resistant

    International Nuclear Information System (INIS)

    Physiological age-dependent variation in radiation resistance was studied for three bacteria that are highly radiation resistant: Micrococcus radiodurans, Micrococcus sp. isolate C-3, and Moraxella sp. isolate 4. Stationary-phase cultures of M. radiodurans and isolate C-3 were much more resistant to gamma radiation than were log-phase cultures. This pattern of relative resistance was reversed for isolate 4. Resistance of isolate 4 to UV light was also greater during log phase, although heat resistance and NaCl tolerance after heat stresses were greater during stationary phase. Radiation-induced injury of isolate 4 compared with injury of Escherichia coli B suggested that the injury process, as well as the lethal process, was affected by growth phase. The hypothesis that growth rate affects radiation resistance was tested, and results were interpreted in light of the probable confounding effect of methods used to alter growth rates of bacteria. These results indicate that dose-response experiments should be designed to measure survival during the most resistant growth phase of the organism under study. The timing is particularly important when extrapolations of survival results might be made to potential irradiation processes for foods. 17 references

  8. Radiation Enhances Regulatory T Cell Representation

    International Nuclear Information System (INIS)

    Purpose: Immunotherapy could be a useful adjunct to standard cytotoxic therapies such as radiation in patients with micrometastatic disease, although successful integration of immunotherapy into treatment protocols will require further understanding of how standard therapies affect the generation of antitumor immune responses. This study was undertaken to evaluate the impact of radiation therapy (RT) on immunosuppressive T regulatory (Treg) cells. Methods and Materials: Treg cells were identified as a CD4+CD25hiFoxp3+ lymphocyte subset, and their fate was followed in a murine TRAMP C1 model of prostate cancer in mice with and without RT. Results: CD4+CD25hiFoxp3+ Treg cells increased in immune organs after local leg or whole-body radiation. A large part, but not all, of this increase after leg-only irradiation could be ascribed to radiation scatter and Treg cells being intrinsically more radiation resistant than other lymphocyte subpopulations, resulting in their selection. Their functional activity on a per-cell basis was not affected by radiation exposure. Similar findings were made with mice receiving local RT to murine prostate tumors growing in the leg. The importance of the Treg cell population in the response to RT was shown by systemic elimination of Treg cells, which greatly enhanced radiation-induced tumor regression. Conclusions: We conclude that Treg cells are more resistant to radiation than other lymphocytes, resulting in their preferential increase. Treg cells may form an important homeostatic mechanism for tissues injured by radiation, and in a tumor context, they may assist in immune evasion during therapy. Targeting this population may allow enhancement of radiotherapeutic benefit through immune modulation.

  9. Radiation Enhances Regulatory T Cell Representation

    Energy Technology Data Exchange (ETDEWEB)

    Kachikwu, Evelyn L.; Iwamoto, Keisuke S.; Liao, Yu-Pei; DeMarco, John J.; Agazaryan, Nzhde [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States); Economou, James S. [Department of Surgical Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States); McBride, William H. [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States); Schaue, Doerthe, E-mail: dschaue@mednet.ucla.edu [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA (United States)

    2011-11-15

    Purpose: Immunotherapy could be a useful adjunct to standard cytotoxic therapies such as radiation in patients with micrometastatic disease, although successful integration of immunotherapy into treatment protocols will require further understanding of how standard therapies affect the generation of antitumor immune responses. This study was undertaken to evaluate the impact of radiation therapy (RT) on immunosuppressive T regulatory (Treg) cells. Methods and Materials: Treg cells were identified as a CD4{sup +}CD25{sup hi}Foxp3{sup +} lymphocyte subset, and their fate was followed in a murine TRAMP C1 model of prostate cancer in mice with and without RT. Results: CD4{sup +}CD25{sup hi}Foxp3{sup +} Treg cells increased in immune organs after local leg or whole-body radiation. A large part, but not all, of this increase after leg-only irradiation could be ascribed to radiation scatter and Treg cells being intrinsically more radiation resistant than other lymphocyte subpopulations, resulting in their selection. Their functional activity on a per-cell basis was not affected by radiation exposure. Similar findings were made with mice receiving local RT to murine prostate tumors growing in the leg. The importance of the Treg cell population in the response to RT was shown by systemic elimination of Treg cells, which greatly enhanced radiation-induced tumor regression. Conclusions: We conclude that Treg cells are more resistant to radiation than other lymphocytes, resulting in their preferential increase. Treg cells may form an important homeostatic mechanism for tissues injured by radiation, and in a tumor context, they may assist in immune evasion during therapy. Targeting this population may allow enhancement of radiotherapeutic benefit through immune modulation.

  10. Radiation resistance of microorganisms from radiation sterilization processing environments

    International Nuclear Information System (INIS)

    The radiation resistance of microorganisms was examined on the samples of dust collected from the radiation sterilization processing environments including assembly, storage, and sterilization plant areas. The isolation of radiation resistant strains was performed by irradiation with screening doses ranging from 10 to 35 kGy and test pieces containing 106 to 108 CFU in dried serum-broth, representing 100 to 5000 colonies of primary cultures of microorganisms from 7 different sites. In an examination of 16900 colonies of aerobic microorganisms from 3 hygienically controlled production sites and 4 uncontrolled ones, 30 strains of bacteria were isolated. Of those 15 were classified as genus Bacillus, 9 as Micrococcus and 6 as Sarcina. The results are presented and discussed. (author)

  11. Sustainably Sourced, Thermally Resistant, Radiation Hard Biopolymer

    Science.gov (United States)

    Pugel, Diane

    2011-01-01

    This material represents a breakthrough in the production, manufacturing, and application of thermal protection system (TPS) materials and radiation shielding, as this represents the first effort to develop a non-metallic, non-ceramic, biomaterial-based, sustainable TPS with the capability to also act as radiation shielding. Until now, the standing philosophy for radiation shielding involved carrying the shielding at liftoff or utilizing onboard water sources. This shielding material could be grown onboard and applied as needed prior to different radiation landscapes (commonly seen during missions involving gravitational assists). The material is a bioplastic material. Bioplastics are any combination of a biopolymer and a plasticizer. In this case, the biopolymer is a starch-based material and a commonly accessible plasticizer. Starch molecules are composed of two major polymers: amylase and amylopectin. The biopolymer phenolic compounds are common to the ablative thermal protection system family of materials. With similar constituents come similar chemical ablation processes, with the potential to have comparable, if not better, ablation characteristics. It can also be used as a flame-resistant barrier for commercial applications in buildings, homes, cars, and heater firewall material. The biopolymer is observed to undergo chemical transformations (oxidative and structural degradation) at radiation doses that are 1,000 times the maximum dose of an unmanned mission (10-25 Mrad), indicating that it would be a viable candidate for robust radiation shielding. As a comparison, the total integrated radiation dose for a three-year manned mission to Mars is 0.1 krad, far below the radiation limit at which starch molecules degrade. For electron radiation, the biopolymer starches show minimal deterioration when exposed to energies greater than 180 keV. This flame-resistant, thermal-insulating material is non-hazardous and may be sustainably sourced. It poses no hazardous

  12. Radiation resistive properties of optical fibers, 2

    International Nuclear Information System (INIS)

    The radiation resistive properties of optical fibers largely depend on the manufacturing methods and conditions because the properties are related to the types and quantity of imperfections in the cores. In this study, the properties of pure silica base fibers and SiO2-GeO2 base fibers were investigated. As the pure silica base fibers, three kinds of the fibers different in base materials were prepared all into SI type pure quartz core, boron and fluorine containing clad fibers, one of which having deuterated OD radicals. As the SiO2-GeO2 base fibers, two kinds of the GI fibers deuterated and treated with chlorine were used. In both types, the dependence of photo bleaching effect on light power and the dependence of loss increasing property on radiation dose rate were examined. The results are as follows: (1) the dependence on light power in three kinds of pure silica core fibers was the most in the fiber of OH radical 800 ppm and chlorine content 100 ppm, and the least in the fiber of OH radical 800 ppm and chlorine content 0 ppm; (2) the radiation resistance of deuterated silica core fiber was good in spite of a small amount of total OH radical (OH + OD); (3) photo bleaching effect was large when the total radiation dose was small, and radiation hardening effect became larger as the total dose increased, in the light power dependence in a long time continuous irradiation; (4) deuterated SiO2-GeO2 fibers had a little photo bleaching effect, and showed an equivalent radiation resistance to that of pure silica fibers at high radiation dose rate and in low light power condition in about 104 R total dose. (Wakatsuki, Y)

  13. Resistance to the ionizing radiation in cells of human melanoma. Role of the antioxidant enzymes and of the free radicals of the oxygen

    International Nuclear Information System (INIS)

    The malignant melanoma is a highly aggressive and potentially lethal type of skin cancer. Previously we have reported that the cellular human lines of melanoma WM35 and M15 are resistant to the ionizing radiation (IR). The histamine (HA) although it has a regulator effect of the cellular proliferation in these lines, it is not capable of to modify the response to the IR like it makes with other malignant cellular lines. To investigate the bases of the radioresistance of the melanoma lines we have studied in the WM35 the production of free radicals of oxygen (ROS), the activity of the antioxidant enzymes and their modifications by action of the IR and of the HA. In studies in vitro the cells were treated with HA 10 μM from 20 hs before being irradiated with a dose of 2 Gy (source 137Cs, dose rate 7.7 Gy/min). The ROS levels, superoxide anion (O2-) and hydrogen peroxide (H2O2) its were measured by flow cytometry using fluorescent coloring and the activity of dismutase superoxide (SOD), Catalase (CAT) and Glutathion Peroxidase (GPx) its were determined by spectrophotometric techniques and the protein levels by Western blot. The results indicate that in the cells WM35 the HA increases the production of H2O2 in 96% and it diminishes lightly (17%) the levels of O2- . On the contrary, the IR diminishes the levels of H2O-2 in 47% and it increases in 46% those of O2-. In the irradiated cells the HA power the decrease of H2O2 produced by the IR. The variation of the enzymes activity is coincident with these changes in the levels of ROS: the treatment with HA increases the activity of SOD and it diminishes that of CAT in cells without irradiating; on the other hand, in the irradiated cells the HA it diminishes the SOD significantly. On the base of these results we can conclude that the levels of H2O2 are directly related with the sensitivity of the cells WM35 to the IR. The HA is able to modulate the activity of the antioxidant enzymes and the levels of ROS. The IR activates

  14. Treatment Resistance Mechanisms of Malignant Glioma Tumor Stem Cells

    Directory of Open Access Journals (Sweden)

    Philip G.R. Schmalz

    2011-02-01

    Full Text Available Malignant gliomas are highly lethal because of their resistance to conventional treatments. Recent evidence suggests that a minor subpopulation of cells with stem cell properties reside within these tumors. These tumor stem cells are more resistant to radiation and chemotherapies than their counterpart differentiated tumor cells and may underlie the persistence and recurrence of tumors following treatment. The various mechanisms by which tumor stem cells avoid or repair the damaging effects of cancer therapies are discussed.

  15. Treatment Resistance Mechanisms of Malignant Glioma Tumor Stem Cells

    OpenAIRE

    Schmalz, Philip G.R.; Park, John K.; Shen, Michael J.

    2011-01-01

    Malignant gliomas are highly lethal because of their resistance to conventional treatments. Recent evidence suggests that a minor subpopulation of cells with stem cell properties reside within these tumors. These tumor stem cells are more resistant to radiation and chemotherapies than their counterpart differentiated tumor cells and may underlie the persistence and recurrence of tumors following treatment. The various mechanisms by which tumor stem cells avoid or repair the damaging effects o...

  16. Treatment Resistance Mechanisms of Malignant Glioma Tumor Stem Cells

    International Nuclear Information System (INIS)

    Malignant gliomas are highly lethal because of their resistance to conventional treatments. Recent evidence suggests that a minor subpopulation of cells with stem cell properties reside within these tumors. These tumor stem cells are more resistant to radiation and chemotherapies than their counterpart differentiated tumor cells and may underlie the persistence and recurrence of tumors following treatment. The various mechanisms by which tumor stem cells avoid or repair the damaging effects of cancer therapies are discussed

  17. Isolation of radiation-resistant bacteria without exposure to irradiation

    International Nuclear Information System (INIS)

    Resistance to desiccation was utilized in the selection of highly radiation-resistant asporogenous bacteria from nonirradiated sources. A bacterial suspension in phosphate buffer was dried in a thin film at 250C and 33% relative humidity. Storage under these conditions for 15 days or more reduced the number of radiation-sensitive bacteria. Further selection for radiation-resistant bacteria was obtained by irradiation of bacteria on velveteen in the replication process, therby avoiding the toxic effect of irradiated media. The similarity of radiation resistance and identifying characteristics in irradiated and non-irradiated isolates should allay some concerns that highly radiation-resistance bacteria have been permanently altered by radiation selection

  18. Study on radiation resistance of photomultipliers

    International Nuclear Information System (INIS)

    The radiation stability of the FEU-115 photoelectron multiplier with windows of the C96-1 glass, dynode systems of the alloyed type photomultiplier of MgF2 and their radiation resistant glasses C95-2, C50 is studied. It is shown that no changes are observed in transmission of photocathode of the C96-1 glass by doses up to 35 Mrad, the FEU-115 signals -up to Mrad, as well as the increase in the dynode systems of the alloyed-type - up to 100 Mrad

  19. Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

    Energy Technology Data Exchange (ETDEWEB)

    Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min; Lapidus, Alla; Copeland, Alex; Kim, Edwin; Land, Miriam; Mavrommatis, Konstantinos; Pitluck, Samuel; Richardson, Paul M.; Detter, Chris; Brettin, Thomas; Saunders, Elizabeth; Lai, Barry; Ravel, Bruce; Kemner, Kenneth M.; Wolf, Yuri I.; Sorokin, Alexander; Gerasimova, Anna V.; Gelfand, Mikhail S.; Fredrickson, James K.; Koonin, Eugene V.; Daly, Michael J.

    2007-07-24

    Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at itsoptimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to

  20. Radiation-Resistant Vegetative Bacteria in a Proposed System of Radappertization of Meats

    International Nuclear Information System (INIS)

    After irradiation in the frozen state with 1 Mrad fresh minced pork or chicken contained approximately 10 - 100 colony-forming units of highly radiation resistant asporogenous bacteria per gram. Some of these had greater radiation resistance than Clostridium botulinum spores. Much of the radiation resistance was apparent as a shoulder in the death curve, which was markedly reduced by heating prior or subsequent to irradiation. Nature of the meat, such as variation in fat content (5-44%), had no significant effect on the radiation resistance of bacteria therein. Even though these bacteria were isolated from meat, it was not a favourable microenvironment for their growth. The water activity was too low. Heat sensitivity of isolates indicated the pre-irradiation enzyme inactivation treatment required for radappertization of meats would destroy or injure most vegetative cells. Thus, the combined process of heat, irradiation, and unfavourable microenvironment would ensure that these radiation resistant cells would not be a problem in radappertized meats. (author)

  1. Genetic variation in resistance to ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, F.J.

    1989-01-01

    The very reactive superoxide anion O[sub 2] is generated during cell respiration as well as during exposure to ionizing radiation. Organisms have evolved different mechanisms to protect against the deleterious effects of reduced oxygen species. The copper-zinc superoxide dismutase is a eukaryotic cytoplasmic enzyme that protects the cell by scavenging superoxide radicals and dismutating them to hydrogen peroxide and molecular oxygen: 20[sub 2][sup [minus

  2. Radiation resistant multicomponent inorganic materials for homogeneous EM-calorimeters

    International Nuclear Information System (INIS)

    With the development of a new generation of particle accelerators the interest for radiation resistant materials using for EM-calorimeters capable of withstanding a high radiation environment (107 rad/yr) has been increasing. The radiation resistance of fluoride solid solutions and heavy crystal oxides is investigated. A series of multicomponent crystals, solid solutions on the base of CeF2 and CdF2 with the radiation resistance above 109 rad is presented. 24 refs.; 4 figs

  3. Low-dose radiation enhances susceptibility to cisplatin in resistant ovarian cancer cells via downregulation of ERCC1 and Bcl-2

    Institute of Scientific and Technical Information of China (English)

    Xiaoran Liu; Donghai Liang; Tao Jiang; Qing Dong; Hongsheng Yu 

    2016-01-01

    Objective Ovarian cancer is one of the leading causes of mortality in patients with malignant gyneco-logical tumors. After surgical intervention for ovarian cancer, cisplatin (DDP)-based chemotherapy is the first-line treatment. However, a major chal enge to treating ovarian cancer is the development of chemore-sistance. Thus, the first aim of this study was to determine whether low-dose radiation could enhance the susceptibility of resistant ovarian cancer cel s to DDP. The second aim was to provide new strategies for treating DDP-resistant ovarian cancer by examining its mechanism. Methods A cel counting kit-8 (CCK8) assay was performed to measure cel proliferation. Flow cytometry was utilized to quantify the apoptosis of DDP-resistant ovarian cancer cel s (SKOV3/DDP) using Annexin V and propidium iodide staining. Real-time quantitative (qPCR) was used to analyze the messenger RNA (mRNA) expression levels of excision repair cross complementing-group 1 (ERCC1) and B-cel lymphoma 2 (Bcl-2) in SKOV3/DDP. Results The IC50 values of the control, conventional-dose, and low-dose groups were 9.367 ± 0.16, 9.289 ± 0.16, and 3.847 ± 0.15, respectively (P Conclusion Low-dose radiation enhanced the sensitivity of resistant ovarian cancer cel s to DDP, pos-sibly by decreasing the DNA repair capacity of tumor cel s and promoting apoptosis.

  4. Data on radiation resistance of lubricating oil

    International Nuclear Information System (INIS)

    This report presents data of radiation resistance of commercial lubricating oils. Data included are the radiation induced change of properties such as kinematic viscosity, total acid number, flash point, pour point, specific gravity and color, and the results by instrumental analysis such as gas analysis by gas chromatography, ESR spectra, infrared spectra, mass spectra, and molecular weight distribution by liquid chromatography. Twenty-seven different kinds of commercial lubricating oils including mineral oils, a synthetic hydrocarbon oil, ester lubricants, a polyether, silicone oils, florinated oils and aromatic oils were irradiated with 60Co γ-rays at room temperature in a vacuum, in air and under bubbling oxygen. The irradiation was carried out up to 30 MGy at a dose rate of 10 kGy/h. (author)

  5. Thermal and radiation resistance of stabilized LDPE

    Energy Technology Data Exchange (ETDEWEB)

    Zaharescu, T., E-mail: traian_zaharescu@yahoo.co [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); Jipa, S. [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); ' Valahia' University of Targoviste, Faculty of Sciences, Targoviste 130024 (Romania); Henderson, D. [Trinity College, Hartford, CT 06106 (United States); Kappel, W. [INCDIE ICPE CA, Department of Radiation Processing, 313 Splaiul Unirii, P.O. Box 149, Bucharest 030138 (Romania); Maris, D.A.; Maris, M. [' Ovidius' University, 7 Ilarie Voronca St, P.O. Box 8700, Constanta (Romania)

    2010-03-15

    The effect of capsaicin on the radiation stability of low density polyethylene was accomplished by applying the chemiluminescence procedure. The neat and modified polymer with 0.25% and 0.50% (w/w) capsaicin were exposed to gamma-irradiation in air receiving 10, 20 and 30 kGy. The synergistic effect due to the presence of metallic selenium was demonstrated. The significant improvement in oxidation induction time was obtained demonstrating the efficient antioxidant activity of capsaicin in LDPE. The simultaneous protection action of metallic selenium in LDPE/capsaicin systems brought about a supplementary enhancement in the oxidation resistance of irradiated samples.

  6. Thermal and radiation resistance of stabilized LDPE

    International Nuclear Information System (INIS)

    The effect of capsaicin on the radiation stability of low density polyethylene was accomplished by applying the chemiluminescence procedure. The neat and modified polymer with 0.25% and 0.50% (w/w) capsaicin were exposed to γ-irradiation in air receiving 10, 20 and 30 kGy. The synergistic effect due to the presence of metallic selenium was demonstrated. The significant improvement in oxidation induction time was obtained demonstrating the efficient antioxidant activity of capsaicin in LDPE. The simultaneous protection action of metallic selenium in LDPE/capsaicin systems brought about a supplementary enhancement in the oxidation resistance of irradiated samples.

  7. A Novel Radiation-Resistant Strain of Filobasidium sp. Isolated from the West Sea of Korea

    International Nuclear Information System (INIS)

    A novel radiation-resistant Filobasidium sp. yeast strain was isolated from seawater. Along with this strain, a total of 656 yeast isolates were purified from seawater samples collected from three locations in the West Sea of Korea and assessed for their radiation tolerance. Among these isolates, five were found to survive a 5 kGy radiation dose. The most radiation resistant strain was classified as Filobasidium sp. based on 18S rDNA sequence analysis and hence was named Filobasidium RRY1 (Radiation-Resistant Yeast 1). RRY1 differed from F. elegans, which is closely related to RRY1, in terms of the optimal growth temperature and radiation resistance, and was resistant to high doses of γ-ionizing radiation (D10: 6-7 kGy). When exposed to a high dose of 3 kGy irradiation, the RRY1 cells remained intact and undistorted, with negligible cell death. When these irradiated cells were allowed to recover, the cells fully repaired their genomic DNA within 3 h of growth recovery. This is the first report in which a radiation-resistant response has been investigated at the physiological, morphological, and molecular levels in a strain of Filobasidium sp. (author)

  8. Radiation Resistance Studies of Amorphous Silicon Alloy Photovoltaic Materials

    Science.gov (United States)

    Woodyard, James R.

    1994-01-01

    The radiation resistance of commercial solar cells fabricated from hydrogenated amorphous silicon alloys was investigated. A number of different device structures were irradiated with 1.0 MeV protons. The cells were insensitive to proton fluences below 1E12 sq cm. The parameters of the irradiated cells were restored with annealing at 200 C. The annealing time was dependent on proton fluence. Annealing devices for one hour restores cell parameters for fluences below lE14 sq cm require longer annealing times. A parametric fitting model was used to characterize current mechanisms observed in dark I-V measurements. The current mechanisms were explored with irradiation fluence, and voltage and light soaking times. The thermal generation current density and quality factor increased with proton fluence. Device simulation shows the degradation in cell characteristics may be explained by the reduction of the electric field in the intrinsic layer.

  9. ABC transporter activity linked to radiation resistance and molecular subtype in pediatric medulloblastoma

    OpenAIRE

    Ingram, Wendy J; Crowther, Lisa M.; Little, Erica B; Freeman, Ruth; Harliwong, Ivon; Veleva, Desi; Hassall, Timothy E; Remke, Marc; Taylor, Michael D.; Hallahan, Andrew R

    2013-01-01

    Background Resistance to radiation treatment remains a major clinical problem for patients with brain cancer. Medulloblastoma is the most common malignant brain tumor of childhood, and occurs in the cerebellum. Though radiation treatment has been critical in increasing survival rates in recent decades, the presence of resistant cells in a substantial number of medulloblastoma patients leads to relapse and death. Methods Using the established medulloblastoma cell lines UW228 and Daoy, we devel...

  10. Breast cancer stem cells and radiation

    Science.gov (United States)

    Phillips, Tiffany Marie

    2007-12-01

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

  11. Effects of T cell depletion in radiation bone marrow chimeras. II. Requirement for allogeneic T cells in the reconstituting bone marrow inoculum for subsequent resistance to breaking of tolerance

    International Nuclear Information System (INIS)

    The ability of normal recipient-type lymphocytes to break tolerance in long-term allogenic radiation chimeras has been investigated. Reconstitution of lethally irradiated mice with a mixture of syngeneic and allogeneic T cell-depleted (TCD) bone marrow (BM) has previously been shown to lead to mixed chimerism and permanent, specific tolerance to donor and host alloantigen (3-5). If allogeneic T cells are not depleted from the reconstituting inoculum, complete allogeneic chimerism results; however, no clinical evidence for GVHD is observed, presumably due to the protective effect provided by syngeneic TCD BM. This model has now been used to study the effects of allogenic T cells administered in reconstituting BM inocula on stability of long-term tolerance. We have attempted to break tolerance in long-term chimeras originally reconstituted with TCD or non-TCD BM by challenging them with inocula containing normal, nontolerant recipient strain lymphocytes. tolerance was broken with remarkable ease in recipients of mixed marrow inocula in which both original BM components were TCD. In contrast, tolerance in chimeras originally reconstituted with non-TCD allogeneic BM was not affected by such inocula. Susceptibility to loss of chimerism and tolerance was not related to initial levels of chimerism per se, but rather to T cell depletion of allogeneic BM, since chimeras reconstituted with TCD allogeneic BM alone (mean level of allogeneic chimerism 98%) were as susceptible as mixed chimeras to the tolerance-breaking effects of such inocula. The possible contribution of GVH reactivity to this resistance was investigated using an F1 into parent strain combination. In these animals, the use of non-TCD F1 BM inocula for reconstitution did not lead to resistance to the tolerance-breaking effects of recipient strain splenocytes

  12. Radiation resistance of microorganisms on unsterilized infusion sets

    DEFF Research Database (Denmark)

    Christensen, E. Ahrensburg; Kristensen, H.; Hoborn, J.; Miller, A.

    1991-01-01

    Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor in a steriliza......Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor in a...

  13. Radiation resistance of microorganisms on unsterilized infusion sets

    DEFF Research Database (Denmark)

    Christensen, E. Ahrensburg; Kristensen, H.; Hoborn, J.;

    1991-01-01

    Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor in a steriliza......Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor...

  14. p53 mutations increase resistance to ionizing radiation

    International Nuclear Information System (INIS)

    Mouse and human tumors of diverse origin frequently have somatically acquired mutations or rearrangements of the p53 gene, or they have lost one or both copies of the gene. Although wild-type p53 protein is believed to function as a tumor-suppressor gene, it is as yet unclear how p53 mutations lead to neoplastic development. Wild-type p53 has been postulated to play a role in DNA repair, suggesting that expression of mutant forms of p53 might alter cellular resistance to the DNA damage caused by γ radiation. Moreover, p53 is thought to function as a cell cycle checkpoint after irradiation, also suggesting that mutant p53 might change the cellular proliferative response to radiation. The authors have used transgenic mice expressing one of two mutant alleles of p53 to test this prediction. Their results show that expression of both mutant variants of the mouse p53 gene significantly increases the cellular resistance of a variety of hematopoietic cell lineages to γ radiation. These observations provide direct evidence that p53 mutations affect the cellular response to DNA damage, either by increasing DNA repair processes or, possibly, by increasing cellular tolerance to DNA damage. The association of p53 mutations with increased radioresistance suggests possible mechanisms through which alterations in the p53 gene might lead to oncogenic transformation. 53 refs., 5 figs

  15. Genetic resistance in experimental autoimmune encephalomyelitis. I. Analysis of the mechanism of LeR resistance using radiation chimeras

    International Nuclear Information System (INIS)

    Experimental autoimmune encephalomyelitis (EAE) is a cell-mediated autoimmune disease of the central nervous system that has been extensively studied in the rat. The Lewis rat is highly susceptible to the induction of EAE, while the Lewis resistant (LeR) rat is known to be resistant. In this paper, we demonstrate that the LeR rat, which was derived from the Lewis strain by inbreeding of fully resistant animals, is histocompatible with the Lewis strain. Radiation chimeras, a tool for distinguishing between immunologic and nonimmunologic resistance mechanisms, were utilized to analyze the cellular mechanisms involved in genetic resistance to EAE. By transplanting bone marrow cells from LeR rats into irradiated Lewis recipients, Lewis rats were rendered resistant to EAE induction. Likewise, transplanting Lewis bone marrow cells into irradiated LeR recipients rendered LeR rats susceptible. Mixed lymphoid cell chimeras using bone marrow, spleen, and thymus cells in Lewis recipient rats revealed individual lymphoid cell types and cell interactions that significantly affected the incidence and severity of EAE. Our results suggest that LeR resistance is mediated by hematopoietic/immune cells, and that cells located in the spleen appear to play a critical role in the resistance/susceptibility to EAE induction. Depletion of splenic adherent cells did not change the patterns of EAE resistance. In vivo cell mixing studies suggested the presence of a suppressor cell population in the LeR spleen preparations which exerted an inhibitory effect on Lewis autoimmune responses. Thus, the mechanism of LeR resistance appears to be different from that in other EAE-resistant animals

  16. Radiation resistant modified polypropylene; Polipropylen modyfikowany odporny radiacyjnie

    Energy Technology Data Exchange (ETDEWEB)

    Bojarski, J.; Zimek, Z. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

    1997-10-01

    Radiation technology for production of radiation resistant polypropylene for medical use has been presented. The method consists in radiation induced copolymerization of polypropylene with ethylene and addition of small amount of copolymer of polyethylene and vinyl acetate. The material of proposed composition has a very good mechanical properties and elevated radiation resistivity decided on possibility of radiosterilization of products made of this material and designed for medical use. 3 figs, 3 tabs.

  17. Characteristics on radiation-resistance physiology and biochemistry of microorganism

    International Nuclear Information System (INIS)

    The purpose of this study is to estimate radiation quality and dose of mixed beam irradiation using bacteria. This time we have irradiated synchrotron X-rays and high energy Fe ions to various microorganisms (e.g extremophiles) and assessed their survivability with Most Probably Number (MPN), cellular adenosine triphosphate (ATP) and genomic DNA fragmentation. Irradiation of 500 MeV Fe ion at a dose rate of 0.172 Gy/s was carried out at National Institute of Radiological Sciences (NIRS) Heavy Ion Medical Accelerator in Chiba (HIMAC) against wet and freeze-dried cells of highly radioresistant bacteria genus Deinococcus and Rubrobacter, highly stress-resistant spore-former family Bacilliceae and radiosensitive Escherichia coli. Freeze dried highly radioresistant bacteria and E. coli cells showed higher survivability than their wet cells. But highly stress-resistant spores have not changed their survivability wet or freeze-dried. ATP showed exponential decrease in wet cells against to the dose. In addition, genomic DNA fragmentation was not easy to generated in freeze-dried cells. (author)

  18. Multidrug resistance in tumour cells: characterisation of the multidrug resistant cell line K562-Lucena 1

    Directory of Open Access Journals (Sweden)

    VIVIAN M. RUMJANEK

    2001-03-01

    Full Text Available Multidrug resistance to chemotherapy is a major obstacle in the treatment of cancer patients. The best characterised mechanism responsible for multidrug resistance involves the expression of the MDR-1 gene product, P-glycoprotein. However, the resistance process is multifactorial. Studies of multidrug resistance mechanisms have relied on the analysis of cancer cell lines that have been selected and present cross-reactivity to a broad range of anticancer agents. This work characterises a multidrug resistant cell line, originally selected for resistance to the Vinca alkaloid vincristine and derived from the human erythroleukaemia cell K562. This cell line, named Lucena 1, overexpresses P-glycoprotein and have its resistance reversed by the chemosensitisers verapamil, trifluoperazine and cyclosporins A, D and G. Furthermore, we demonstrated that methylene blue was capable of partially reversing the resistance in this cell line. On the contrary, the use of 5-fluorouracil increased the resistance of Lucena 1. In addition to chemotherapics, Lucena 1 cells were resistant to ultraviolet A radiation and hydrogen peroxide and failed to mobilise intracellular calcium when thapsigargin was used. Changes in the cytoskeleton of this cell line were also observed.A resistência a múltiplos fármacos é o principal obstáculo no tratamento de pacientes com câncer. O mecanismo responsável pela resistência múltipla mais bem caracterizado envolve a expressão do produto do gene MDR-1, a glicoproteína P. Entretanto, o processo de resistência tem fatores múltiplos. Estudos de mecanismos de resistência m��ltipla a fármacos têm dependido da análise de linhagens celulares tumorais que foram selecionadas e apresentam reatividade cruzada a uma ampla faixa de agentes anti-tumorais. Este trabalho caracteriza uma linhagem celular com múltipla resistência a fármacos, selecionada originalmente pela resistência ao alcalóide de Vinca vincristina e derivado

  19. Studies on the radiation resistances of bioburden for medical devices

    Energy Technology Data Exchange (ETDEWEB)

    Sekiguchi, Masayuki; Tabei, Masae [Tokyo Metropolitan Isotope Research Center (Japan)

    1997-03-01

    Radiation resistances of reference bacteria strains and the bioburden obtained from hypodermic needles were estimated with gamma- and electron- irradiators calibrated with NPL (National Physics Laboratory) alanine dosimeter. Radiation resistances of the TSB-bacteria suspension samples dried on glass test tubes showed about two times higher than those of the water-bacteria suspension dried on glass fiber paper or paper filter. Radiation resistances of the dried TSB-bacteria suspension samples irradiated by both gamma rays and electron beams were fluctuated. The overall increase ratio of radiation resistance was estimated by dividing D-values of TSB-bacteria suspension samples by that of water-bacteria suspension samples for individual bacteria. Then, the survival curve of hypodermic needle bioburden revised by the increase ratio was obtained, and which compared with that of standard distribution of radiation resistances of ISO(SDR). (author)

  20. Studies on the radiation resistances of bioburden for medical devices

    International Nuclear Information System (INIS)

    Radiation resistances of reference bacteria strains and the bioburden obtained from hypodermic needles were estimated with gamma- and electron- irradiators calibrated with NPL (National Physics Laboratory) alanine dosimeter. Radiation resistances of the TSB-bacteria suspension samples dried on glass test tubes showed about two times higher than those of the water-bacteria suspension dried on glass fiber paper or paper filter. Radiation resistances of the dried TSB-bacteria suspension samples irradiated by both gamma rays and electron beams were fluctuated. The overall increase ratio of radiation resistance was estimated by dividing D-values of TSB-bacteria suspension samples by that of water-bacteria suspension samples for individual bacteria. Then, the survival curve of hypodermic needle bioburden revised by the increase ratio was obtained, and which compared with that of standard distribution of radiation resistances of ISO(SDR). (author)

  1. Radiation resistant optical fiber for FBG based sensing

    OpenAIRE

    Pal, A.; Dhar, A.; Sen, R; Ams, M.; Sun, T.; Grattan, K.T.V.

    2013-01-01

    Radiation-resistant optical fibers have been fabricated through MCVD process. The low radiation-induced-absorption in the fiber and few picometer shifting of Bragg-wavelength of the FBG under γ-exposure indicate its potential application for sensing in radiation environment.

  2. Radiation response in prostate cancer stem cells

    International Nuclear Information System (INIS)

    The full text of the publication follows. Introduction: Currently, there is no successful treatment for secondary prostate cancer. Resistance of secondary tumours and metastases to radiotherapy and chemotherapy might be explained by cancer stem cells (CSCs). Prostate (P) CSCs are rare cells defined by cell surface markers, CD133+, a2b1integrinhi and CD44+, and are capable of self-renewal, differentiation and invasion in vitro and tumour initiation in vivo. Hypothesis: PCSCs have an alternative DNA damage response following radiation and are resistant to radiation treatment. Methods: Primary prostate (benign and cancer) epithelial stem (SC) transit amplifying (TA, CD133-/a2b1integrinhi/CD44+) and committed basal (CB, CD133-/a2b1integrinlo/CD44+) cells were exposed to 2 Gy of radiation (IR) to induce a DNA damage response. Immunofluorescence was used to quantify nuclear foci, representative of DNA damage response proteins (g-H2AX, 53BP1, phosphorylated ATM/ATR substrates, phospho-Chk2Th68). Immunofluorescence was also used to co-stain for heterochromatin and DNA damage markers. Comet assays (neutral and alkaline) were used to directly assess DNA damage. Results: In benign and cancer cells, the SCs had a lower percentage of cells containing initial foci (30 min post-IR), compared to the TA and CB cells. At 24 h post-IR there was a reduced percentage of cells positive for foci in TA and CB cells suggesting repair. Whilst there were also signs of repair in benign SCs, in the PCSCs there was an increase in percentage of cells positive for foci at 24 h, indicative of a delayed damage response. Comet assays indicated that SCs sustain different kinds of DNA damage to TA and CB cells. Heterochromatin staining indicated that DNA damage foci preferentially formed in euchromatin. Future work: Further studies will include apoptosis and clonogenic assays to measure PCSC survival. In addition, PCSC chromatin status will be examined to elucidate DNA repair kinetics. If we are able

  3. Effect of radiation resistance additives for insulation materials

    International Nuclear Information System (INIS)

    For the electric wires and cables used in radiation environment such as nuclear power stations and fuel reprocessing facilities, the properties of excellent radiation resistance are required. For these insulators and sheath materials, ethylene propylene rubber, polyethylene and other polymers have been used, but it cannot be said that they always have good radiation resistance. However, it has been well known that radiation resistance can be improved with small amount of additives, and heat resistance and burning retarding property as well as radiation resistance are given to the insulators of wires and cables for nuclear facilities by mixing various additives. In this research, the measuring method for quantitatively determining the effect of Anti-rad (radiation resistant additive) was examined. Through the measurement of gel fraction, radical formation and decomposed gas generation, the effect of Anti-rad protecting polymers from radiation deterioration was examined from the viewpoint of chemical reaction. The experimental method and the results are reported. The radiation energy for cutting C-H coupling is polymers is dispersed by Anti-rad, and the probability of cutting is lowered. Anti-rad catches and extinguishes radicals that start oxidation reaction. (K.I.)

  4. Cell Phone RF Radiation

    Science.gov (United States)

    Abdul-Razzaq, Wathiq

    2015-01-01

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

  5. The radiation resistance of the bioburden from medical devices

    International Nuclear Information System (INIS)

    An extensive study of the radiation resistance of microbial species constituting the bioburden of a number of different medical devices obtained from Japanese medical device manufacturers has been carried out. A standard protocol for determining radiation resistance was used and validated at the fourteen centres involved in the study. Individual microbial isolates from the bioburden obtained from seven different devices manufactured in these centres were studied. A total of 3742 unselected isolates were obtained, of which 197 failed to survive long enough for subsequent radiation resistance studies. The remainder were subjected to an initial screen test to identify those organisms that were sensitive to the lethal effects of radiation with a D10 of < 1.5kGy. The 465 isolates that survived the screen doses were then tested for survival in an incremental series of radiation doses using methods similar to those of Whitby (1979) and Yan and Tallentire (1995). The isolates from 'dry' devices were more resistant than those obtained from the one water filled ('wet') device studied. The overall distribution of radiation resistance among the isolates was considered to be similar to that forming the 'Standard Distribution of Resistance' (SDR) included in the ISO International Standard 11137 'Sterilization of Health Care Products - Requirements for validation and routine control - Radiation sterilization'

  6. The radiation resistance of the bioburden from medical devices

    Energy Technology Data Exchange (ETDEWEB)

    Takehisa, M.; Shintani, H.; Sekiguchi, M.; Koshikawa, T.; Oonishi, T.; Tsuge, M.; Sou, K.; Yamase, Y.; Kinoshita, S.; Tsukamoto, H.; Endo, T.; Yashima, K.; Nagai, M.; Ishigaki, K.; Sato, Y.; Whitby, J. L

    1998-06-01

    An extensive study of the radiation resistance of microbial species constituting the bioburden of a number of different medical devices obtained from Japanese medical device manufacturers has been carried out. A standard protocol for determining radiation resistance was used and validated at the fourteen centres involved in the study. Individual microbial isolates from the bioburden obtained from seven different devices manufactured in these centres were studied. A total of 3742 unselected isolates were obtained, of which 197 failed to survive long enough for subsequent radiation resistance studies. The remainder were subjected to an initial screen test to identify those organisms that were sensitive to the lethal effects of radiation with a D{sub 10} of < 1.5kGy. The 465 isolates that survived the screen doses were then tested for survival in an incremental series of radiation doses using methods similar to those of Whitby (1979) and Yan and Tallentire (1995). The isolates from 'dry' devices were more resistant than those obtained from the one water filled ('wet') device studied. The overall distribution of radiation resistance among the isolates was considered to be similar to that forming the 'Standard Distribution of Resistance' (SDR) included in the ISO International Standard 11137 'Sterilization of Health Care Products - Requirements for validation and routine control - Radiation sterilization'.

  7. The radiation resistance of the bioburden from medical devices

    Science.gov (United States)

    Takehisa, M.; Shintani, H.; Sekiguchi, M.; Koshikawa, T.; Oonishi, T.; Tsuge, M.; Sou, K.; Yamase, Y.; Kinoshita, S.; Tsukamoto, H.; Endo, T.; Yashima, K.; Nagai, M.; Ishigaki, K.; Sato, Y.; Whitby, J. L.

    1998-06-01

    An extensive study of the radiation resistance of microbial species constituting the bioburden of a number of different medical devices obtained from Japanese medical device manufacturers has been carried out. A standard protocol for determining radiation resistance was used and validated at the fourteen centres involved in the study. Individual microbial isolates from the bioburden obtained from seven different devices manufactured in these centres were studied. A total of 3742 unselected isolates were obtained, of which 197 failed to survive long enough for subsequent radiation resistance studies. The remainder were subjected to an initial screen test to identify those organisms that were sensitive to the lethal effects of radiation with a D 10 of < 1.5kGy. The 465 isolates that survived the screen doses were then tested for survival in an incremental series of radiation doses using methods similar to those of Whitby (1979) and Yan and Tallentire(1995). The isolates from "dry" devices were more resistant than those obtained from the one water filled ("wet") device studied. The overall distribution of radiation resistance among the isolates was considered to be similar to that forming the "Standard Distribution of Resistance" (SDR) included in the ISO International Standard 11137 "Sterilization of Health Care Products — Requirements for validation and routine control — Radiation sterilization".

  8. Characteristics on radiation-resistance physiology and biochemistry of microorganism

    International Nuclear Information System (INIS)

    The purpose of this study is to estimate radiation quality and dose of mixed beam irradiation using bacteria. This time we have irradiated synchrotron X-rays and high energy Fe ions to various microorganisms (e.g extremophiles) and assessed their survivability with Most Probably Number (MPN) and cellular adenosine triphosphate (ATP). Irradiation of 500 MeV Fe ion at a dose rate of 0.172 Gy/s was carried out at NIRS HIMAC against the dried cells of highly radioresistant bacteria genus Deinococcus and Rubrobacter, highly stress-resistant spore -former family Bacilliceae and radiosensitive Escherichia coli. Generally similar results to X-ray irradiation were observed, while genus Deinococcus and Rubrobacter, showing survival at the highest experimental dose of 2 kGy. (author)

  9. Resistance to BN myelogenous leukemia in rat radiation chimeras

    International Nuclear Information System (INIS)

    Lewis → LBNFl rat radiation chimeras showed marked resistance to transplanted BN myelogenous leukemia when compared to naive LBNFl, LBNFl → LBNFl, or BN → LBNFl. This occurred in the absence of overt graft versus host disease or of anti-BN response in mixed lymphocyte culture. Bone marrow specific antigens may serve as the target of the resistance mechanism. (author)

  10. Radiation hardened high efficiency silicon space solar cell

    International Nuclear Information System (INIS)

    A silicon solar cell with AMO 19% Beginning of Life (BOL) efficiency is reported. The cell has demonstrated equal or better radiation resistance when compared to conventional silicon space solar cells. Conventional silicon space solar cell performance is generally ∼ 14% at BOL. The Radiation Hardened High Efficiency Silicon (RHHES) cell is thinned for high specific power (watts/kilogram). The RHHES space cell provides compatibility with automatic surface mounting technology. The cells can be easily combined to provide desired power levels and voltages. The RHHES space cell is more resistant to mechanical damage due to micrometeorites. Micro-meteorites which impinge upon conventional cells can crack the cell which, in turn, may cause string failure. The RHHES, operating in the same environment, can continue to function with a similar crack. The RHHES cell allows for very efficient thermal management which is essential for space cells generating higher specific power levels. The cell eliminates the need for electrical insulation layers which would otherwise increase the thermal resistance for conventional space panels. The RHHES cell can be applied to a space concentrator panel system without abandoning any of the attributes discussed. The power handling capability of the RHHES cell is approximately five times more than conventional space concentrator solar cells

  11. Radiation Effects of Commercial Resistive Random Access Memories

    Science.gov (United States)

    Chen, Dakai; LaBel, Kenneth; Berg, Melanie; Wilcox, Edward; Kim, Hak; Phan, Anthony; Figueiredo, Marco; Buchner, Stephen; Khachatrian, Ani; Roche, Nicolas

    2014-01-01

    We present results for the single-event effect response of commercial production-level resistive random access memories. We found that the resistive memory arrays are immune to heavy ion-induced upsets. However, the devices were susceptible to single-event functional interrupts, due to upsets from the control circuits. The intrinsic radiation tolerant nature of resistive memory makes the technology an attractive consideration for future space applications.

  12. Comparison of gamma radiation - induced effects in two human prostate cancer cells

    International Nuclear Information System (INIS)

    In this study, the effects of gamma radiation on two hormone refractory human prostate cancer cell lines, DU 145 and PC-3, were followed. It was shown that gamma radiation induced significant inhibition of cell proliferation and viability in dose dependent manner. Antiproliferative effects of radiation were similar in both cell lines, and more pronounced than cytotoxic effects. In addition to that, PC-3 cell line was more resistant to radiation -induced cytotoxicity. (author)

  13. Genetic control of resistance to Coccidioides immitis: a single gene that is expressed in spleen cells determines resistance

    International Nuclear Information System (INIS)

    The authors have previously reported that inbred mice vary widely in their resistance to Coccidioides immitis peritonitis. To investigate the number of genes controlling resistance, (susceptible X resistant)F1 X susceptible backcross mice were tested for resistance to infection. A 1:1 ratio of resistant:susceptible offspring was observed, which is consistent with a single dominant gene determining resistance. To find out whether this gene, which was designated Cms, is expressed in the immune and/or the inflammatory responses, radiation chimeras were constructed by transplanting spleen cells from the resistant F1 mice into the susceptible parental strain. These chimeras were consistently more resistant to infection than the susceptible parental strain. The authors concluded that resistance to C. immitis is determined primarily by a single gene, and that this gene is expressed by spleen cells

  14. A Novel Radiation-Resistant Yeast, Filobasidium elegans RRY1

    International Nuclear Information System (INIS)

    The tolerance to ionizing radiation stress is present among different classes and species of organisms. As listed by Rainey et al., ionizing radiation resistant organisms were isolated from a variety of different sources like processed/canned food items, paper industry, soil and water samples. Apart from extensively reported bacteria and Archea group, many fungal species like Aspergillus, Curvularia, Alternaria, Cryptococcus, and Ustilago maydis have been found to be resistant to ionizing radiation. However, different environmental sources are constantly been explored for novel radioresistant organisms, which can help in understanding the molecular mechanism behind these extreme stress responses. On the basis of this, present study was initiated to find novel radiation resistant yeast from sea water source

  15. A Novel Radiation-Resistant Yeast, Filobasidium elegans RRY1

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harinder; Kim, Ha Ram; Song, Hyun Pa; Lim, Sang Yong; Kim, Dong Ho [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2012-05-15

    The tolerance to ionizing radiation stress is present among different classes and species of organisms. As listed by Rainey et al., ionizing radiation resistant organisms were isolated from a variety of different sources like processed/canned food items, paper industry, soil and water samples. Apart from extensively reported bacteria and Archea group, many fungal species like Aspergillus, Curvularia, Alternaria, Cryptococcus, and Ustilago maydis have been found to be resistant to ionizing radiation. However, different environmental sources are constantly been explored for novel radioresistant organisms, which can help in understanding the molecular mechanism behind these extreme stress responses. On the basis of this, present study was initiated to find novel radiation resistant yeast from sea water source

  16. Space radiation effects on plant and mammalian cells

    Science.gov (United States)

    Arena, C.; De Micco, V.; Macaeva, E.; Quintens, R.

    2014-11-01

    The study of the effects of ionizing radiation on organisms is related to different research aims. The current review emphasizes the studies on the effects of different doses of sparsely and densely ionizing radiation on living organisms, with the final purpose of highlighting specific and common effects of space radiation in mammals and plants. This topic is extremely relevant in the context of radiation protection from space environment. The response of different organisms to ionizing radiation depends on the radiation quality/dose and/or the intrinsic characteristics of the living system. Macromolecules, in particular DNA, are the critical targets of radiation, even if there is a strong difference between damages encountered by plant and mammalian cells. The differences in structure and metabolism between the two cell types are responsible for the higher resistance of the plant cell compared with its animal counterpart. In this review, we report some recent findings from studies performed in Space or on Earth, simulating space-like levels of radiation with ground-based facilities, to understand the effect of ionizing radiation on mammalian and plant cells. In particular, our attention is focused on genetic alterations and repair mechanisms in mammalian cells and on structures and mechanisms conferring radioresistance to plant cells.

  17. Radiation-resistant vegetative bacteria in a proposed system of radappertization of meats

    International Nuclear Information System (INIS)

    After irradiation in the frozen state with 1 Mrad fresh minced pork or chicken contained approximately 10-100 colony-forming units of highly radiation resistant asporogenous bacteria per gram. Some of these had greater radiation resistance than Clostridium botulinum spores. Much of the radiation resistance was apparent as a shoulder in the death curve, which was markedly reduced by heating prior or subsequent to irradiation. Nature of the meat, such as variation in fat content (5-44%), had no significant effect on the radiation resistance of bacteria therein. Even though these bacteria were isolated from meat, it was not a favourable microenvironment for their growth. The water activity was too low. Heat sensitivity of isolates indicated the pre-irradiation enzyme inactivation treatment required for radappertization of meats would destroy or injure most vegetative cells. Thus, the combined process of heat, irradiation, and unfavourable microenvironment would ensure that these radiation resistant cells would not be a problem in radappertized meats. (author)

  18. Development of radiation resistant electrical cable insulations

    International Nuclear Information System (INIS)

    Two new polyethylene cable insulations have been formulated for nuclear applications, and have been tested under gamma radiation. Both insulations are based on low density polyethylene, one with PbO and the other with Sb2O3 as additives. The test results show that the concept of using inorganic antioxidants to retard radiation initiated oxidation (RIO) is viable. PbO is more effective than Sb2O3 in minimizing RIO

  19. Radiation Resistant Magnets for the RIA Fragment Separator

    CERN Document Server

    Zeller, Al; Gupta, Ramesh C; Ronningen, Reginald; Sherrill, Bradley

    2005-01-01

    The high radiation fields around the production target and the beam dump in the fragment separator at the Rare Isotope Accelerator requires that radiation resistant magnets be used. Because large apertures and high gradients are required for the quadrupoles and similar demanding requirements for the dipole and sextupoles, resistive coils are difficult to justify. The radiation heating of any materials at liquid helium temperatures also requires that superconducting versions of the magnets have low cold-masses. The final optical design has taken the practical magnets limits into account and sizes and fields adjusted to what is believed to be achievable with technology that is possible with sufficient R&D. Designs with higher obtainable current densities and having good radiation tolerances that use superconducting coils are presented, as well as the radiation transport calculations that drive the material parameters.

  20. Radiation resistant polymers and coatings for nuclear fuel reprocessing plants

    International Nuclear Information System (INIS)

    Polymer based materials are extensively used in the nuclear industry for the reprocessing of spent fuels in highly radioactive and corrosive environment. Hence, these polymer materials are susceptible to damage by ionizing radiation, resulting in the degradation in properties. Polymers containing aromatic molecules generally possess higher resistance to radiation degradation than the aliphatic polymers. For improving the radiation resistance of polymers various methods are reported in the literature. Among the aromatic polymers, polyetheretherketone (PEEK) has the radiation tolerance up to 10 Mega Grey (MGy). To explore the possibility of enhancing the radiation resistance of PEEK, a study was initiated to develop PEEK - ceramic composites and evaluate the effect of radiation on the properties of the composites. PEEK and PEEK - alumina (micron size) composites were irradiated in a gamma chamber using 60Co source and the degradation in mechanical, structural, electrical and thermal properties, gel fraction, coefficient of friction and morphology were investigated. The degradation in the mechanical properties owing to radiation could be reduced by adding alumina filler to PEEK. Nano alumina filler was observed to be more effective in suppressing the damage caused by radiation on the polymer, when compared to micron alumina filler. For the protection of aluminium components in the manipulators and the rotors and stators of the motors of the centrifugal extractors employed in the plant from the attack by nitric acid vapour, PEEK coating based on liquid dispersion was developed, which has resistance to radiation, chemicals and wear. The effect of radiation and chemical vapour on the properties of the PEEK coating was estimated. The performance of the coating in the plant was evaluated and the coating was found to give adequate protection to the motors of centrifugal extractors against corrosion. (author)

  1. Radiation curable resistant coatings and their preparation

    International Nuclear Information System (INIS)

    A prepolymer containing unsaturated hydrocarbon groups is prepared and mixed on a roller mill with one or more acrylic ester monomers and various additives to make a coating formulation of a desired viscosity. In general, low viscosity formulations are used for overprint varnishes, on paper or foil, or with pigments, for certain types of printing inks. Higher viscosity formulations are used to apply thick films on panels, tiles, or other bodies. Thin films are cured to hardness by brief exposure to ultraviolet light. Thicker films require more energetic radiation such as plasma arc and electron beam radiation. The prepolymers particularly useful for making such radiation curable coatings are the reaction products of polyether polyols and bis- or polyisocyanates and hydroxy alkenes or acrylic (or methacrylic) hydroxy esters, and, likewise, reactive polyamides modified with dicarboxy alkenes, their anhydrides or esters. A small amount of wax incorporated in the coating formulations results in coatings with release characteristics similar to those of PTFE coatings. 10 claims

  2. Radiation resistance of isotopic structural graphites

    International Nuclear Information System (INIS)

    One investigated into radiation change of dimensions and of other features of some isotropic fine-grained structural graphites irradiated by high doses in BOR-60 reactor under 350-450 deg C. It was determined that at the attained doses (up to 2.8x1022 n/cm2) one observed, no secondary swelling followed by secondary change. It is shown that at similar perfection of crystalline structure the process parameters, that is: coke class, coarseness of grains, formation technique, availability of sealing sintering-impregnations determining graphite initial features affect the level of radiation change of its properties

  3. Stem cells in radiation and oral cancer research

    International Nuclear Information System (INIS)

    Cancer stem cells (CSCs) are defined as a small sub population of cancer cells that constitute a pool of self sustaining cells with the exclusive ability to cause the heterogeneous lineages of cancer cells that comprise the tumour. There are three main characteristics of CSCs. Initially the cell must show potent tumour initiation in that it can regenerate the tumour which it was derived from a limited number of cells. In addition, the cells should demonstrate self renewal in vivo, which is practically observed via regrowth of phenotypically indistinguishable and heterogeneous tumours following serial transplantation of re-isolated CSCs in secondary and tertiary recipients. Finally, the cells must show a differentiation capacity, allowing them to give rise to a heterogeneous progeny, which represents a phenocopy of the original tumour. This article highlights the radiation therapy resulting in radiation resistance in cancer stem cells. (author)

  4. Cell shunt resistance and photovoltaic module performance

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, T.J.; Basso, T.S.; Rummel, S.R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    Shunt resistance of cells in photovoltaic modules can affect module power output and could indicate flawed manufacturing processes and reliability problems. The authors describe a two-terminal diagnostic method to directly measure the shunt resistance of individual cells in a series-connected module non-intrusively, without deencapsulation. Peak power efficiency vs. light intensity was measured on a 12-cell, series-connected, single crystalline module having relatively high cell shunt resistances. The module was remeasured with 0.5-, 1-, and 2-ohm resistors attached across each cell to simulate shunt resistances of several emerging technologies. Peak power efficiencies decreased dramatically at lower light levels. Using the PSpice circuit simulator, the authors verified that cell shunt and series resistances can indeed be responsible for the observed peak power efficiency vs. intensity behavior. The authors discuss the effect of basic cell diode parameters, i.e., shunt resistance, series resistance, and recombination losses, on PV module performance as a function of light intensity.

  5. SU-C-303-01: Activation-Induced Cytidine Deaminase Confers Cancer Resistance to Radiation Therapy

    International Nuclear Information System (INIS)

    Purpose: To study the role of activation-induced cytidine deaminase (AID) in malignant cell resistance to radiation therapy. Methods: We first developed several small devices that could be used to adopt radiation beams from clinical high dose rate brachy therapy (HDR) or linac-based megavoltage machines to perform pre-clinical cell and mouse experiments. Then we used these devices to deliver radiation to AID-positive and AID-silenced cancer cells or tumors formed by these cells in mice. Cells and mice bearing tumors received the same dose under the same experimental conditions. For cells, we observed the apoptosis and the cell survival rate over time. For mice bearing tumors, we measured and recorded the tumor sizes every other day for 4 weeks. Results: For cell experiments, we found that the AID-positive cells underwent much less apoptosis compared with AID-silenced cells upon radiation. And for mouse experiments, we found that AID-positive tumors grew significantly faster than the AID-silenced tumors despite of receiving the same doses of radiation. Conclusion: Our study suggests that AID may confer cancer resistance to radiation therapy, and AID may be a significant biomarker predicting cancer resistance to radiation therapy for certain cancer types

  6. Radiation-resistant micro-organisms isolated from textiles

    International Nuclear Information System (INIS)

    Towels from private homes and public offices and underwear contaminated by being used by employees at a public health laboratory were examined for occurrence of radiation-resistant bacteria and fungi. Three different methods were used for isolation of the most resistant organisms, one with multiplication of the microbial population prior to an irradiation used for selection, and two witout this multiplication and with the organisms placed on membrane filters or in situ on the textiles, respectively. A total of 44 different strains were isolated. Differences in the three methods used for selection of the most radiation-resistant microorganisms were not reflected in the results. 16 pigmentproducing Gram-positive cocci, tentatively classified as Micrococcus radiodurans, were the most radiation-resistant and were isolated in about half of the examinations. Other Gram-positive cocci, nonspore forming rods, some Nocardia and Candida parapsilosis strains and two Bacillus strains constituted the rest of the collection. With few exceptions dose-response curves for the strains were upward convex. D-6 values determined to be between 1.5 megarad for the most radiation sensitive, a Candida, and 5.7 megarad for the most resistant, tentatively classified as M. radiodurans. The D-6 values for the Bacillus strains were in both cases 1.8 megarad, consistent with a D-value of 0.3 megarad. The same resistance is reported to be the maximum resistance for B. pumilus, strain E601, commonly used as reference strain in the literature on radiation sterilization of medical devices and supplies. (author)

  7. Metal-nanotube composites as radiation resistant materials

    Science.gov (United States)

    González, Rafael I.; Valencia, Felipe; Mella, José; van Duin, Adri C. T.; So, Kang Pyo; Li, Ju; Kiwi, Miguel; Bringa, Eduardo M.

    2016-07-01

    The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

  8. Ways of providing radiation resistance of magnetic field semiconductor sensors

    CERN Document Server

    Bolshakova, I A; Holyaka, R; Matkovskii, A; Moroz, A

    2001-01-01

    Hall magnetic field sensors resistant to hard ionizing irradiation are being developed for operation under the radiation conditions of space and in charged particle accelerators. Radiation resistance of the sensors is first determined by the properties of semiconductor materials of sensitive elements; we have used microcrystals and thin layers of III-V semiconductors. Applying complex doping by rare-earth elements and isovalent impurities in certain proportions, we have obtained magnetic field sensors resistant to irradiation by fast neutrons and gamma-quanta. Tests of their radiation resistance were carried out at IBR-2 at the Joint Institute for Nuclear Research (Dubna). When exposed to neutrons with E=0.1-13 MeV and intensity of 10 sup 1 sup 0 n cm sup - sup 2 s sup - sup 1 , the main parameter of the sensors - their sensitivity to magnetic fields - changes by no more than 0.1% up to fluences of 10 sup 1 sup 4 n cm sup - sup 2. Further improvement of radiation resistance of sensor materials is expected by ...

  9. Study of radiation resistance on radiation shielding window glass, (2)

    International Nuclear Information System (INIS)

    Dielectric breakdown test after gamma-irradiation, measurement of radiation induced electric conductivity, and analysis of charge accumulation during irradiation were carried out for F36N glass which is widely used as a radiation shielding window glass, on the basis of the results of the previous report on charge accumulation and coloration in gamma-ray irradiated shielding glass. It was found for different composition of the sample glasses that the analyzed results of charge accumulation is adequately correlated with the results of dielectric breakdown test, dielectric breakdown is not influenced by electric conductivity of un-irradiated glasses and internal distortion in the glass, and that heat-treatment after irradiation is effective to control dielectric breakdown. (author)

  10. A stunning resistance to radiations; Une resistance hors normes aux radiations

    Energy Technology Data Exchange (ETDEWEB)

    Etien, S.

    2010-11-15

    The Deinococus radiodurans bacteria (DRB) can survive extreme radiation doses as high as 100 times the doses that kill other bacteria. The number of DNA breaking due to irradiation is the same as in other bacteria but DRB benefits from a very efficient DNA repairing system. This system relies on the fact that DRB owns 4 to 10 identical copies of its genome and because of this high number of copies the repair process is very likely to find a no-damaged part of the DNA in one copy to reconstitute the DNA. It appears that this process does not involve specific enzymes but enzymes that are present in any other bacteria. The efficiency of the repairing process relies on two things: first, the circular shape of the genome that avoids the spreading in the cell of the DNA breaks, and secondly, the enzymes are protected from irradiation oxidation by a high concentration in manganese and iron. (A.C.)

  11. Radiation resistance measurement method in conforming to ISO and its effects on proof of sterilization

    Energy Technology Data Exchange (ETDEWEB)

    Sekiguchi, Masayuki [Tokyo Metropolitan Isotope Research Center (Japan)

    1997-09-01

    The radiation resistance of spore forming bacteria (78 strains) renatured by reculture of bioburden (BB) in the injection needle was measured by the same method as the standard resistance distribution of radiation sterilization standardized by ISO (International Organization for Standarization). {gamma}-ray irradiation unit corrected by NPL alanine dosimeter was used. When D value of vegetative cell bacteria and spore forming bacteria were estimated to 1 KGy, the resistance distribution was restructured and the effect on sterile dose was discussed. Average D value of spore forming bacteria (78 strains) was 2.51 KGy. Its value is near average D value (2.48 KGy) of the standard resistance distribution of five BB. The fact indicates that good safety likelihood could be obtained by estimating sterile dose by log method using D value of spore forming bacteria obtained in culture media. (S.Y.)

  12. Radiation resistance measurement method in conforming to ISO and its effects on proof of sterilization

    International Nuclear Information System (INIS)

    The radiation resistance of spore forming bacteria (78 strains) renatured by reculture of bioburden (BB) in the injection needle was measured by the same method as the standard resistance distribution of radiation sterilization standardized by ISO (International Organization for Standarization). γ-ray irradiation unit corrected by NPL alanine dosimeter was used. When D value of vegetative cell bacteria and spore forming bacteria were estimated to 1 KGy, the resistance distribution was restructured and the effect on sterile dose was discussed. Average D value of spore forming bacteria (78 strains) was 2.51 KGy. Its value is near average D value (2.48 KGy) of the standard resistance distribution of five BB. The fact indicates that good safety likelihood could be obtained by estimating sterile dose by log method using D value of spore forming bacteria obtained in culture media. (S.Y.)

  13. Radiation-resistant acquired immunity of vaccinated mice to Schistosoma mansoni

    International Nuclear Information System (INIS)

    Vaccination of mice with attenuated cercariae of Schistosoma mansoni induces specific acquired resistance to challenge infection. This resistance is immunologically-mediated, possibly via a delayed-type hypersensitivity. Studies of parasite migration have shown that the protective mechanism operates most effectively in the lungs of vaccinated mice. We have probed the mechanism by exposing mice to 500 rads of gamma radiation before challenge infection. Our results show that the effector mechanism operative against challenge larvae is resistant to radiation. In contrast, classical immune responses are markedly suppressed by the same treatment. While leukocyte populations in the blood fall dramatically after irradiation, numbers of cells recoverable by bronchoalveolar lavage are unaffected. We suggest that vaccination with attenuated cercariae establishes populations of sensitized cells in the lungs which trigger the mechanism of resistance when challenge schistosomula migrate through pulmonary capillary beds. Although the cells may be partially disabled by irradiation, they remain responsive to worm antigens and thereby capable of initiating the elimination mechanism. This hypothesis would explain the radiation resistance of vaccine-induced immunity to S. mansoni

  14. Radiation-resistant acquired immunity of vaccinated mice to Schistosoma mansoni

    Energy Technology Data Exchange (ETDEWEB)

    Aitken, R.; Coulson, P.S.; Dixon, B.; Wilson, R.A.

    1987-11-01

    Vaccination of mice with attenuated cercariae of Schistosoma mansoni induces specific acquired resistance to challenge infection. This resistance is immunologically-mediated, possibly via a delayed-type hypersensitivity. Studies of parasite migration have shown that the protective mechanism operates most effectively in the lungs of vaccinated mice. We have probed the mechanism by exposing mice to 500 rads of gamma radiation before challenge infection. Our results show that the effector mechanism operative against challenge larvae is resistant to radiation. In contrast, classical immune responses are markedly suppressed by the same treatment. While leukocyte populations in the blood fall dramatically after irradiation, numbers of cells recoverable by bronchoalveolar lavage are unaffected. We suggest that vaccination with attenuated cercariae establishes populations of sensitized cells in the lungs which trigger the mechanism of resistance when challenge schistosomula migrate through pulmonary capillary beds. Although the cells may be partially disabled by irradiation, they remain responsive to worm antigens and thereby capable of initiating the elimination mechanism. This hypothesis would explain the radiation resistance of vaccine-induced immunity to S. mansoni.

  15. Functional genetic research for radiation and drug resistant adenocarcinoma and its application

    International Nuclear Information System (INIS)

    The work scope of 'Functional genetic research for radiation and drug resistant adenocarcinoma and its application' had contained the research about effect of transgelin(SM22a), neurotensin, metallothionein-1G transgelin-2 genes on the cell death triggered ionizing radiation, cisplatin, MMS, luteolin and H2O2(toxic agents), which are highly expressed in radiation-induced mutant cells. In this study, to elucidate the role of these proteins in the ionizing radiation (toxic chemicals)-induced cell death, we utilized sensed (or antisense, small interference RNA) cells, which overexpress (or down-regulate) RNAs associated with these proteins biosynthesis, and investigated the effects of these genes on the cytotoxicity caused by ionizing radiation, H2O2 and toxic chemicals. We also investigated the functions of downstream target genes of transgelin such as IGF-1Rβ/PI3K/AKT pathway and transgelin/metallothioneine in A-549 and HepG2 cells because such target genes are able to potentiate the cell-killing or cell protecting effects against radiation

  16. Distributed series resistance effects in solar cells

    DEFF Research Database (Denmark)

    Nielsen, Lars Drud

    1982-01-01

    A mathematical treatment is presented of the effects of one-dimensional distributed series resistance in solar cells. A general perturbation theory is developed, including consistently the induced spatial variation of diode current density and leading to a first-order equivalent lumped resistance...

  17. Radiation resistance studies of amorphous silicon films

    Science.gov (United States)

    Woodyard, James R.; Payson, J. Scott

    1989-01-01

    Hydrogenated amorphous silicon thin films were irradiated with 2.00 MeV helium ions using fluences ranging from 1E11 to 1E15 cm(-2). The films were characterized using photothermal deflection spectroscopy and photoconductivity measurements. The investigations show that the radiation introduces sub-band-gap states 1.35 eV below the conduction band and the states increase supralinearly with fluence. Photoconductivity measurements suggest the density of states above the Fermi energy is not changing drastically with fluence.

  18. Radiation effects on membranes - 1. Cellular permeability and cell survival

    International Nuclear Information System (INIS)

    The effect of various doses of γ radiation (5-60 krad) on the membrane permeability and cell survival of Candida albicans, a pathogenic yeast, was investigated. A reduction in the cell survival and in the accumulation of amino acids (proline, glycine, lysine, and glutamic acid) was observed following irradiation. The rate of oxygen uptake, which is often associated with transport, was also reduced. There was no damage to available sulfhydryl groups following the exposure of cells to various doses of γ radiation. The membrane lipid composition of C. albicans cells can be altered by growing them in alkanes of varying chain lengths. The effects of such altered lipid composition on radiosensitivity was examined. It was observed that C. albicans cells with altered lipid content acquire resistance to γ radiation

  19. The Biology of Allogeneic Hematopoietic Cell Resistance

    Science.gov (United States)

    Shizuru, Judith A.; Bhattacharya, Deepta; Cavazzana-Calvo, Marina

    2016-01-01

    At the most basic level, success of an allogeneic hematopoietic cell transplantation (HCT) procedure relies upon the engraftment of recipients with donor hematopoietic stem cells (HSCs) that will generate blood formation for the life of that individual. The formula to achieve durable HSC engraftment involves multiple factors including the recipient conditioning regimen, the nature of the genetic disparity between donor and recipient, and the content of the hematopoietic graft. Animal and clinical studies have shown that the biology of host resistance is complex, involving both immune and nonimmune elements. In this article, we review the factors that contribute to host resistance, describe emerging concepts on the basic biology of resistance, and discuss hematopoietic resistance as it relates specifically to patients with severe combined immunodeficiencies (SCID)— disorders that bring unique insights into the dynamics of cell replacement by allogeneic HSCs and progenitor cells. PMID:19913629

  20. Radiation Resistant Vanadium-Graphene Nanolayered Composite

    Science.gov (United States)

    Kim, Youbin; Baek, Jinwook; Kim, Sunghwan; Kim, Sangmin; Ryu, Seunghwa; Jeon, Seokwoo; Han, Seung Min

    2016-01-01

    Ultra high strength V-graphene nanolayers were developed for the first time that was demonstrated to have an excellent radiation tolerance as revealed by the He+ irradiation study. Radiation induced hardening, evaluated via nanopillar compressions before and after He+ irradiation, is significantly reduced with the inclusion of graphene layers; the flow stresses of V-graphene nanolayers with 110 nm repeat layer spacing showed an increase of 25% while pure V showed an increase of 88% after He+ dosage of 13.5 dpa. The molecular dynamics simulations confirmed that the graphene interface can spontaneously absorb the nearby crystalline defects that are produced from a collision cascade, thereby enhancing the lifetime of the V-graphene nanolayers via this self-healing effect. In addition, the impermeability of He gas through the graphene resulted in suppression of He bubble agglomerations that in turn reduced embrittlement. In-situ SEM compression also showed the ability of graphene to hinder crack propagation that suppressed the failure. PMID:27098407

  1. Radiation-resistant requirement analysis of device for the advanced spent fuel conditioning process

    International Nuclear Information System (INIS)

    It is known that high levels of radiation can cause significant damage by altering the properties of materials. A practical understanding of the effects of radiation - how radiation affects various types of materials and components - is required to design equipment to operate reliably in a gamma radiation environment. When designing equipment to operate in a high gamma radiation environment, such as will be present in a nuclear spent fuel handling facility, several important steps should be followed. To do this, the system design process in the radiation environment is reviewed. Also, through the investigation of the foreign literature, threshold values are generally reported. The threshold values are normally the dose required to begin degradation in a particular material property. In order to active test of the Advanced spent fuel Conditioning Process(ACP), the radiation-resistant analysis of the device for active test of the ACP are conducted, which is operated in the radiation environment called a hot-cell. For analyzing the radiation effects of the ACP, a gamma dose rates for a hot-cell environment of the ACP are calculated by using the SCALE 4.4 code. Also, the radiation effect analysis of the main device for the ACP such as vol-oxidation, reduction reactor and servo manipulator is performed

  2. Engineering radiation-resistant bacteria for environmental biotechnology.

    Science.gov (United States)

    Daly, M J

    2000-06-01

    Seventy million cubic meters of ground and three trillion liters of groundwater have been contaminated by leaking radioactive waste generated in the United States during the Cold War. A cleanup technology is being developed based on the radiation-resistant bacterium Deinococcus radiodurans, which is being engineered to express bioremediating functions. PMID:10851141

  3. Live-cell luciferase assay of drug resistant cells

    OpenAIRE

    sprotocols

    2015-01-01

    To date, multiplexing cell-based assay is essential for high-throughput screening of molecular targets. Measuring multiple parameters of a single sample increases consistency and decrease time and cost of assay. Functional assay of living cell is useful as a first step of multiplexing assay, because live-cell assay allows following second assay using cell lysate or stained cell. However, live-cell assay of drug resistant cells that are highly activated of drug efflux mechanisms is sometimes u...

  4. ICAM-3, radiation resistance gene, activates PI3K/Akt-CREB-MMPs pathway and promotes migration/invasion of the human non-small cell lung cancer cell NCI-H1299

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jong Kuk; Park, Seon Ho; Hong, Sung Hee; Um, Hong Duck [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Yoo, Young Do [Korea Univ., Seoul (Korea, Republic of)

    2008-05-15

    Cancer cell is characterized by various distinctive functions difference from normal cell. The one of specific properties of cancer is invasion and metastasis. Invasion and metastasis is a multi-step process involving over-expression of proteolytic enzymes such as matrix metalloproteinases (MMPs) and critically dependent on the ability of cells to move away from the primary tumor to gain access to the vascular or lymphatic systems which disperses cells to distant sites, where they can grow in a permissive microenvironment at a secondary location. All of these processes are critically dependent upon the ability of cancer cells to breach the basement membrane and to migrate through neighboring tissues. Cancer cell invasion is an important, tightly regulated process that is related with development, immune response and wound healing. This invasive response is dependent on activation of signaling pathways that result in both short-term and long-term cellular responses. The gene expressions of the cancer cell invasion related-proteolytic enzymes are regulated at the transcriptional level (through AP-1 and NF-kB via mitogen activated protein kinases (MAPKs) and PI3K-Akt pathways) and post-transcriptional levels, and the protein level via their activators or inhibitors, and their cell surface localization. Therefore, the related proteins such as MMPs, MAPK, PI3K, Akt and their regulatory pathway have been considered as promising targets for anti-cancer drugs. In previous reports, Intercellular adherin molecule-3 (ICAM-3) showed increase of radio-resistance and proliferation. We have made ICAM-3 overexpressed cancer cells which shows elevated level of invasion compared with normal cancer cells and its invasion capacity was down regulated with treatment of specific inhibitor for PI3K. These results suggest that ICAM-3 related invasion is associated with PI3K signaling pathway.

  5. ICAM-3, radiation resistance gene, activates PI3K/Akt-CREB-MMPs pathway and promotes migration/invasion of the human non-small cell lung cancer cell NCI-H1299

    International Nuclear Information System (INIS)

    Cancer cell is characterized by various distinctive functions difference from normal cell. The one of specific properties of cancer is invasion and metastasis. Invasion and metastasis is a multi-step process involving over-expression of proteolytic enzymes such as matrix metalloproteinases (MMPs) and critically dependent on the ability of cells to move away from the primary tumor to gain access to the vascular or lymphatic systems which disperses cells to distant sites, where they can grow in a permissive microenvironment at a secondary location. All of these processes are critically dependent upon the ability of cancer cells to breach the basement membrane and to migrate through neighboring tissues. Cancer cell invasion is an important, tightly regulated process that is related with development, immune response and wound healing. This invasive response is dependent on activation of signaling pathways that result in both short-term and long-term cellular responses. The gene expressions of the cancer cell invasion related-proteolytic enzymes are regulated at the transcriptional level (through AP-1 and NF-kB via mitogen activated protein kinases (MAPKs) and PI3K-Akt pathways) and post-transcriptional levels, and the protein level via their activators or inhibitors, and their cell surface localization. Therefore, the related proteins such as MMPs, MAPK, PI3K, Akt and their regulatory pathway have been considered as promising targets for anti-cancer drugs. In previous reports, Intercellular adherin molecule-3 (ICAM-3) showed increase of radio-resistance and proliferation. We have made ICAM-3 overexpressed cancer cells which shows elevated level of invasion compared with normal cancer cells and its invasion capacity was down regulated with treatment of specific inhibitor for PI3K. These results suggest that ICAM-3 related invasion is associated with PI3K signaling pathway

  6. Molecular mechanisms of bortezomib resistant adenocarcinoma cells.

    Directory of Open Access Journals (Sweden)

    Erika Suzuki

    Full Text Available Bortezomib (Velcade™ is a reversible proteasome inhibitor that is approved for the treatment of multiple myeloma (MM. Despite its demonstrated clinical success, some patients are deprived of treatment due to primary refractoriness or development of resistance during therapy. To investigate the role of the duration of proteasome inhibition in the anti-tumor response of bortezomib, we established clonal isolates of HT-29 adenocarcinoma cells adapted to continuous exposure of bortezomib. These cells were ~30-fold resistant to bortezomib. Two novel and distinct mutations in the β5 subunit, Cys63Phe, located distal to the binding site in a helix critical for drug binding, and Arg24Cys, found in the propeptide region were found in all resistant clones. The latter mutation is a natural variant found to be elevated in frequency in patients with MM. Proteasome activity and levels of both the constitutive and immunoproteasome were increased in resistant cells, which correlated to an increase in subunit gene expression. These changes correlated with a more rapid recovery of proteasome activity following brief exposure to bortezomib. Increased recovery rate was not due to increased proteasome turnover as similar findings were seen in cells co-treated with cycloheximide. When we exposed resistant cells to the irreversible proteasome inhibitor carfilzomib we noted a slower rate of recovery of proteasome activity as compared to bortezomib in both parental and resistant cells. Importantly, carfilzomib maintained its cytotoxic potential in the bortezomib resistant cell lines. Therefore, resistance to bortezomib, can be overcome with irreversible inhibitors, suggesting prolonged proteasome inhibition induces a more potent anti-tumor response.

  7. Development of application technology of radiation-resistant microorganism

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong Ho; Lim, Sang Yong; Joe, Min Ho; Jung, Jin Woo; Jung, Sun Wook; Song, Du Sup; Choi, Young Ji [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-02-15

    The scope of the project is divided into of three parts; (i) to define the survival strategy of radiation-resistant microbes, especially Deinococcus (ii) acquisition of gene resources encoding the novel protein and related with the production of functional materials (iii) development of control technology against radiation-resistant microbes. To this aim, first, the whole transcriptional response of the D. radiodurans strain haboring pprI mutation, which plays an important role in radiation resistance, was analyzed by cDNA microarray. The anti-oxidant activity of the major carotenoid of D. radiodurans, deinoxanthin, was analyzed and the strain was constructed, in which the gene necessary for bio- synthesis of deinoxanthin is deleted. The response to cadmium of D. radiodurans was also investigated through cDNA microarray analysis. Radiogenic therapy, one of the cancer treatments, is designed to use radiation-inducible gene for the treatment. To develop the gene-transfer vehicle for radiogenic therapy, we have investigated the virulence mechanism of Salmonella, which is tumor-targeting bacteria and studied the synergistic effect of some anti-cancer agents on radiation treatment for cancer. Finally, we confirmed that irradiation could decompose a fungus toxin, patulin, into various harmless by-products.

  8. [Role of constitutive and inducible repair in radiation resistance of Escherichia coli].

    Science.gov (United States)

    Gulevich, E P; Kuznetsova, V N; Verbenko, V N

    2011-07-01

    Radiation resistance of Escherichia coil cells depends on how efficiently DNA is recovered after damage, which is determined by the function of constitutive and inducible repair branches. The effects of additional mutations of the key genes of constitutive and inducible repair (recA, lexA, recB, polA, lig, gyr, recE, recO, recR, recJ, recQ, uvrD, helD, recN, and ruv) on radiation resistance were studied in E. coli K-12 strain AB 1157 and highly radiation-resistant isogenic strain Gam(r)444. An optimal balance ensuring a high gamma resistance of the Gam(r)444 radiation-resistant E. coli mutant was due to expression of the key SOS repair genes (recA, lexA, recN, and ruv) and activation of the presynaptic functions of the RecF homologous recombination pathway as a result of a possible mutation of the uvrD gene, which codes for repair helicase II. PMID:21938951

  9. 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

  10. Radiation Resistance Test of Wireless Sensor Node and the Radiation Shielding Calculation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Liqan; Sur, Bhaskar [Atomic Energy of Canada Limited, Ontario (Canada); Wang, Quan [University of Western Ontario, Ontario (Canada); Deng, Changjian [The University of Electronic Science and Technology, Chengdu (China); Chen, Dongyi; Jiang, Jin [Applied Physics Branch, Ontario (Korea, Republic of)

    2014-08-15

    A wireless sensor network (WSN) is being developed for nuclear power plants. Amongst others, ionizing radiation resistance is one essential requirement for WSN to be successful. This paper documents the work done in Chalk River Laboratories of Atomic Energy of Canada Limited (AECL) to test the resistance to neutron and gamma radiation of some WSN nodes. The recorded dose limit that the nodes can withstand before being damaged by the radiation is compared with the radiation environment inside a typical CANDU (CANada Deuterium Uranium) power plant reactor building. Shielding effects of polyethylene, cadmium and lead to neutron and gamma radiations are also analyzed using MCNP simulation. The shielding calculation can be a reference for the node case design when high dose rate or accidental condition (like Fukushima) is to be considered.

  11. Development of resistant materials to beam impact and radiation damage

    Science.gov (United States)

    Kawai, Masayoshi; Kokawa, Hiroyuki; Okamura, Hiroshi; Kawasaki, Akira; Yamamura, Tsutomu; Hara, Nobuyoshi; Akao, Noboru; Futakawa, Masatoshi; Kikuchi, Kenji

    2006-09-01

    Materials that have strong resistance to both beam impact (or shock-wave) and radiation damage are required for the beam target of an intense accelerator and space applications. Recently, Futakawa et al. found in their experiments that Kolsterising specimens have a stronger resistance to pitting than SS316 CW. A similar effect can be expected for other hardening treatments, and new material development is hopeful. Accordingly, we have started the development of high-performance materials by organizing the project team from KEK, JAEA and universities. In this paper, the scope of the project is introduced. Recent topics involve the development of intergranular crack (IGC)-resistant austenitic stainless-steel, AlN-TiN ceramics and cladding techniques of thin tantalum or CrN film on a tungsten target by means of a molten-salt method and ion-beam-enhanced deposition. New observations on corrosion resistance are presented.

  12. Mutant radiation-resistance alleles from the Escherichia coli Gamr444 mutant: Cloning and preliminary characterization

    International Nuclear Information System (INIS)

    Mutant alleles Gamr, which are able to increase the resistance to radiation of Escherichia coli wild-type cells, were cloned from the hyperradioresistant mutant Gamr444 on plasmid mini-Mu-vector MudII4042. The influence of recombinant plasmids on the sensitivity of wild-type and mutant (recA and htpR) cells to γ-irradiation was studied. It was shown that the enhanced resistance of the Gamr444 strain to radiation was caused by mutations of two different classes, dominant and recessive. The cloned recessive mutation gamr12 increases resistance to radiation only after homogenotization, that is, radiation-induced transfer from the plasmid to the chromosome, and it imposes constitutive expression of the heat-shock promoter htpG. Dominant mutant gamr alleles are active in the trans-position. A mutation-insertion into a chromosomal gene impaired by one of the dominant mutations, gamr18, was constructed. The insertion causes drastic cell radiosensitization on the recBC sbcB background and probably disturbs the RecF pathway of recombination and repair. Dominant plasmids of the second type lead to the RecA-independent inhibition of DNA postirradiation degradation. The radioprotective action of recessive and dominant gamr mutations is additive

  13. Radiation-Resistant Micrococcus luteus SC1204 and Its Proteomics Change Upon Gamma Irradiation.

    Science.gov (United States)

    Deng, Wuyuan; Yang, Yang; Gao, Peng; Chen, Hao; Wen, Wenting; Sun, Qun

    2016-06-01

    To explore the radiation-resistance mechanisms in bacteria, a radiation-resistant strain SC1204 was isolated from the surrounding area of a (60)Co-γ radiation facility. SC1204 could survive up to 8 kGy dose of gamma irradiation and was identified as Micrococcus luteus by phylogenetic analysis of 16S rRNA gene sequences. Its proteomic changes under 2-kGy irradiation were examined by two-dimensional electrophoresis followed by MALDI-TOF-TOF/MS analysis. The results showed that at least 24 proteins displayed significant changes (p radiation stress, among which 22 were successfully identified and classified into the major functional categories of metabolism, energy production and conservation, translation, ribosomal structure, and biogenesis. Among these proteins, leucyl aminopeptidase involved in synthesis of glutathione was the most abundant induced protein during postirradiation recovery, indicating that anti-oxidation protection was the most important line of defense in SC1204 against radiation. The next abundant protein was phosphoribosyl aminoimidazole carboxamide formyltransferase/IMP cyclohydrolase (AICAR Tfase/IMPCH), the key enzyme in the biosynthetic pathway of purine that is anti-radiation compound. Other proteins changing significantly (p radiation exposure included urocanate hydratase, dihydrolipoyl dehydrogenase, succinyl-CoA synthetase subunit alpha, phosphoglycerate kinase, cell division protein FtsZ, elongation factor Ts and Tu, translation elongation factor Tu and G, 30S ribosomal protein S1, histidyl-tRNA synthetase, and arginyl-tRNA synthetase, which were considered to be the key proteins in urocanate metabolism, tricarboxylic acid cycle, glycolysis, cell division process, and synthesis process of proteins. Therefore, these proteins may also play important roles in radiation resistance in M. luteus. PMID:26920868

  14. 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

  15. Role of manganese in the resistance of Micrococcus radiodurans to ionizing radiation

    International Nuclear Information System (INIS)

    Micrococcus radiodurans possesses a very high level of intracellular manganese compared to other organisms. This manganese content has previously been shown to participate in the exceptional ulraviolet radiation resistance of M. radiodurans. This study was undertaken to determine the role of manganese in the ionizing radiation resistant of M. radiodurans. The results indicate that manganese is essential for DNA degradation to occur during irradiation. Manganese has also proven essential for the second phase of post-irradiation thymine base damage removal. These factors work together to increase the rate of recovery from radiation damage, which is reflected in a larger Dq, D37 and exponential portion of the survival curve of high Mn-grown cells

  16. Development of superior radiation resistant materials and cables. 2

    International Nuclear Information System (INIS)

    Many nuclear power plants have been constructed in Japan and electric power generation is now highly dependent on this technology. Therefore, the needs for facilities that will enrich and reprocess nuclear fuel from nuclear power stations will be high. As there are areas with high levels of radiation, the cables which can be used in these environments are needed. We have developed a superior radiation-resistant cable which uses halogen flame-retardant materials. This radiation-resistant cable consists of Ethylene-propylene rubber (EPDM) insulation and Chlorosulfonated polyethylene (CSM) sheath can be safely used in areas with high levels of radiation. We developed this product to aid in disaster prevention. Non-halogen, flame-retardant EPDM is used for the insulation, and low-halogen, flame-retardant CSM and new non-halogen, flame-retardant materials are used for the sheath. These cables have superior flame-retardant properties and generate little smoke on corrosive gas. This products can hence reduce the danger of a secondary disaster in a fire. We expect that these cables will find application in areas with high levels of radiation. (author)

  17. Resistance of cell membranes to different detergents

    OpenAIRE

    Schuck, Sebastian; Honsho, Masanori; Ekroos, Kim; Shevchenko, Andrej; Simons, Kai

    2003-01-01

    Partial resistance of cell membranes to solubilization with mild detergents and the analysis of isolated detergent-resistant membranes (DRMs) have been used operationally to define membrane domains. Given the multitude of detergents used for this purpose, we sought to investigate whether extraction with different detergents might reflect the same underlying principle of domain formation. We therefore compared the protein and lipid content of DRMs prepared with a variety of detergents from two...

  18. Isolation of radiation resistant fungal strains from highly radioactive field

    International Nuclear Information System (INIS)

    This study examined the radiation resistance of fungal flora isolated from the hot-lab around the radiation sources, cobalt 137 and radium 226. The predominant mould species were: Aspergillus flavus, A. Niger, penicillium chrysogenum, cladosporium herbarum, fusarium oxysporum and alternaria citri. The D 10 values of F. Oxysporum; 2.00 KGy, A. Flavus; 1.40 KGy, P. chrysogenum; 1.15 KGy, and A. citri; 0.95 KGy, are about 1.67, 3.10, 1.92 and 1.36 folds as the D10 values of the same isolates recovered from soil

  19. The influence of the stem cell marker ALDH and the EGFR-PI3 kinase act signaling pathway on the radiation resistance of human tumor cell lines; Der Einfluss des Stammzellmarkers ALDH und des EGFR-PI3 Kinase-Akt Signalwegs auf die Strahlenresistenz humaner Tumorzelllinien

    Energy Technology Data Exchange (ETDEWEB)

    Mihatsch, Julia

    2014-07-14

    Cancer is the second leading cause of death in industriated nations. Besides surgery and chemotherapy, radiotherapy (RT) is an important approach by which about 60% of patients are treated. The response of these patients to RT is very heterogenous. On the one hand, there are patients with tumors which are radiosensitive and can be cured, but on the other hand patients bear tumors which are quite resistant to radiotherapy. A Radioresistant phenotype of tumor cells causes treatment failure consequently leading to a limited response to radiotherapy. It is proposed, that radiotherapy outcome mainly depends on the potential of radiation on controlling growth, proliferation and survival of a specific population of tumor cells called cancer stem cells (CSCs) or tumor-initiating cells. Based on experimental studies so far reported it is assumed that the population of CSC varies in tumors from different entities and is relatively low compared to the tumor bulk cells in general. According to the CSC hypothesis, it might be concluded that the differential response of tumors to radiotherapy depends on CSC populations, since these supposedly slow replicating cells are able to initiate a tumor, to self renew indefinitely and to generate the differentiated progeny of a tumor. Besides the role of cancer stem cells in radiotherapy response, ionizing radiation (IR) activates the epidermal growth factor receptor (EGFR) and its downstream signaling pathways such as phosphoinositide 3-kinase (PI3K)/Akt, mitogen-activated protein kinase (MAPK) and Janus kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathways. Among these pathways, PI3K/Akt is one of the most important pathways involved in post-irradiation survival: Activation of Akt results in activation of DNA-dependent protein kinase, catalytic subunit (DNA-PKcs). DNA-PKcs is a core enzyme involved in repair of IR-induced DNA-double strand breaks (DNA-DSB) through non-homologous end joining (NHEJ). The aim of the

  20. Cancer stem cells and chemoradiation resistance

    International Nuclear Information System (INIS)

    Cancer is a disease of genetic and epigenetic alterations, which are emphasized as the central mechanisms of tumor progression in the multistepwise model. Discovery of rare subpopulations of cancer stem cells (CSCs) has created a new focus in cancer research. The heterogeneity of tumors can be explained with the help of CSCs supported by antiapoptotic signaling. CSCs mimic normal adult stem cells by demonstrating resistance to toxic injuries and chemoradiation therapy. Moreover, they might be responsible for tumor relapse following apparent beneficial treatments. Compared with hematopoietic malignancies, conventional therapy regimes in solid tumors have improved the overall survival marginally, illustrating the profound impact of treatment resistance. This implies that the present therapies, which follow total elimination of rapidly dividing and differentiated tumor cells, need to be modified to target CSCs that repopulate the tumor. In this review article, we report on recent findings regarding the involvement of CSCs in chemoradiation resistance and provide new insights into their therapeutic implications in cancer. (author)

  1. Draft Genome Sequence of Kocuria rhizophila RF, a Radiation-Resistant Soil Isolate.

    Science.gov (United States)

    Mehrabadi, Jalil Fallah; Mirzaie, Amir; Ahangar, Nahid; Rahimi, Arian; Rokni-Zadeh, Hassan

    2016-01-01

    Kocuria rhizophila RF, a soil isolate from Iran, is a radiation-resistant bacterium. Only a limited amount of genomic information for radiation-resistant bacteria is currently available. Here, we report the draft genome sequence of this bacterium, providing knowledge to aid in the discovery of the genomic basis of its resistance to radiation. PMID:26966202

  2. Restoration of Chinese hamster cell radiation resistance by the human repair gene ERCC-5 and progress in molecular cloning of this gene

    International Nuclear Information System (INIS)

    The uv-sensitive Chinese hamster cell uv-135 is being used to identify and isolate the human gene, ERCC-5, which corrects nucleotide excision repair in this incision-defective mutant. A cosmid library, constructed from a 30 transformant of uv-135, has been screened for transfected gpt and human Alu family sequences. An ordered physical map of overlapping positives cosmids has been determined. Molecular evidence suggests a region of this map of <40 Kbp contains the ERCC-5 gene. 10 refs., 2 figs

  3. High resistance of some oligotrophic bacteria to ionizing radiation

    International Nuclear Information System (INIS)

    The resistance of seven cultures of eutrophic and oligotrophic bacteria to gamma radiation (at doses up to 360 Gy) was investigated. The bacteria under study were divided into three groups according to their survival ability after irradiation. Methylobacterium organophilum and open-quotes Pedodermatophilus halotoleransclose quotes (LD50 = 270 Gy) were highly tolerant. By their tolerance, these organisms approached Deinococcus radiodurans. Aquatic ring-shaped (toroidal) bacteria Flectobacillus major and open-quotes Arcocella aquaticaclose quotes (LD5 = 173 and 210 Gy, respectively) were moderately tolerant. Eutrophic Pseudomonas fluorescens and Escherichia coli (LD50 = 43 and 38 Gy, respectively) were the most sensitive. X-ray microanalysis showed that in tolerant bacteria the intracellular content of potassium increased and the content of calcium decreased after irradiation. No changes in the element composition of the eutrophic bacterium E. coli were detected. Possible mechanisms of the resistance of oligotrophic bacteria to gamma radiation are discussed

  4. Negative differential resistance devices for generation of terahertz radiation

    OpenAIRE

    Eisele, H.

    2015-01-01

    This paper discusses the principles of operation, state of the art, and future potential of active two-terminal devices for generation of low-noise, continuous-wave terahertz radiation. These devices use transit-time, transferred-electron, and quantum-mechanical effects (or a combination of them) to create a negative differential resistance (NDR) at the frequency of interest. Many different types of NDR devices have been proposed since the earliest days of semiconductor devices and studied in...

  5. The resistive bolometer for radiated power measurement on EAST

    International Nuclear Information System (INIS)

    The resistive bolometer system has been successfully employed on experimental advanced superconducting tokamak for the first time to measure the radiated power of plasma. The bolometer detectors are based on 4 μm thick Pt absorbers deposited on 1.5 μm thick SiN membranes. The system consists of 3 cameras with a total of 48 channels. The detector and the system setup are described in detail. The detector calibration and typical measurement results are presented as well.

  6. Target cells involved in radiation and radiation leukemia virus leukemogenesis

    International Nuclear Information System (INIS)

    Comparative studies concerned with the induction and early proliferation phases of preleukemic cells in relation to host environments using radiation or radiation leukemia virus as the leukemogenic agents, indicated different developmental pathways. The lack of thymus in mice exposed to fractionated irradiation did not prevent preleukemic cell induction but did interfere with the incidence of RadLV induced preleukemic cells. Thymus removal within several days following RadLV inoculation prevented the establishment of preleukemic cells in the bone marrow. The radiation induced preleukemic cells in the bone marrow. The radiation induced preleukemic cells were not lysed by anti-Thy-1.2 serum treatment and guinea pig complement whereas the RadLV induced ones were lysed to different degrees. Elimination of Thy-1.2 bearing cells from the virus induced preleukemic population reduced the development of overt T leukemias of donor origin. The thymus seemed of essential importance for establishing the proliferation of RadLV induced preleukemic cells but not for those induced by fractionated irradiation

  7. Some resistance mechanisms to ultraviolet radiation; Algunos mecanismos de resistencia a radiacion ultravioleta

    Energy Technology Data Exchange (ETDEWEB)

    Alcantara D, D. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2002-12-15

    The cyclical exposure of bacterial cells to the ultraviolet light (UV) it has as consequence an increment in the resistance to the lethal effects of this type of radiation, increment that happens as a result of a selection process of favorable genetic mutations induced by the same UV light. With object to study the reproducibility of the genetic changes and the associate mechanisms to the resistance to UV in the bacteria Escherichia coli, was irradiated cyclically with UV light five different derived cultures of a single clone, being obtained five stumps with different resistance grades. The genetic mapping Hfr revealed that so much the mutation events like of selection that took place during the adaptation to the UV irradiation, happened of random manner, that is to say, each one of the resistant stumps it is the result of the unspecified selection of mutations arisen at random in different genes related with the repair and duplication of the DNA. (Author)

  8. Repair of radiation damage in mammalian cells

    International Nuclear Information System (INIS)

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

  9. Resistance of Salmonella enteritidis variety typhimurium to gamma radiation

    International Nuclear Information System (INIS)

    The use of ionizing radiations to kill microrganisms responsible for food deterioration, and toxinfections is an example of peaceful use of nuclear energy. Food toxinfections are, amongus, produced mostly by Salmonella enteritidis var. typhimurium. Due to the pauncity of information on the resistance to gamma radiation of Salmonella enteritidis var. typhimurium this paper has the aim to define the 60-Cobalt gamma radiation lethal dose to these bacteria, in experimentally contaminated milk by samples recovered from our geographycal area. One hundred nineteen samples of milk containing about 150.000 bacteria per ml were irradiated with doses ranging from 100 to 1.100 Gy. Two samples of surving bacteria were again irradiated by doses up to 2.500 Gy. The bacteria not previously irradiated were killed by doses of 1.100 Gy. It was concluded that the 60-Cobalt gamma radiation minimal lethal dose to Salmonella enteritidis var. typhimurium is 1.200 Gy. The surviving strains to smaller doses than 1.200 Gy when re-irradiated prompt the forthcoming of more radio-resistant germs. (author)

  10. Haemopoietic cell renewal in radiation fields.

    Science.gov (United States)

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

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a "turbulence region" for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a "blood stem cell bank" might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container. PMID:11539991

  11. Haemopoietic cell renewal in radiation fields

    Science.gov (United States)

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

    1994-10-01

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

  12. Radiation resistance diagnostics of wide-gap optical materials

    Science.gov (United States)

    Feldbach, Eduard; Tõldsepp, Eliko; Kirm, Marco; Lushchik, Aleksandr; Mizohata, Kenichiro; Räisänen, Jyrki

    2016-05-01

    Novel approach in the detection of radiation damage created by ion beams in optical materials was demonstrated. Protons of the energy of 100 keV and fluence of 1017 cm-2 create sufficient amount of crystal lattice defects in the thin surface layer for testing of optical materials needed for future fusion reactors. These structural defects can be detected and analysed using the spectra of cathodoluminescence excited in the irradiated layer by an electron beam with adjustable energy. The method was verified by the enhanced intensity of F-type luminescence that reflects the creation of radiation-induced oxygen vacancies in MgO and Al2O3 crystals. Low radiation resistance of nominally pure (Lu1-xGdx)2SiO5 crystals was demonstrated by almost total suppression of intrinsic luminescence after the same irradiation.

  13. Designing Radiation Resistance in Materials for Fusion Energy

    Science.gov (United States)

    Zinkle, S. J.; Snead, L. L.

    2014-07-01

    Proposed fusion and advanced (Generation IV) fission energy systems require high-performance materials capable of satisfactory operation up to neutron damage levels approaching 200 atomic displacements per atom with large amounts of transmutant hydrogen and helium isotopes. After a brief overview of fusion reactor concepts and radiation effects phenomena in structural and functional (nonstructural) materials, three fundamental options for designing radiation resistance are outlined: Utilize matrix phases with inherent radiation tolerance, select materials in which vacancies are immobile at the design operating temperatures, or engineer materials with high sink densities for point defect recombination. Environmental and safety considerations impose several additional restrictions on potential materials systems, but reduced-activation ferritic/martensitic steels (including thermomechanically treated and oxide dispersion-strengthened options) and silicon carbide ceramic composites emerge as robust structural materials options. Materials modeling (including computational thermodynamics) and advanced manufacturing methods are poised to exert a major impact in the next ten years.

  14. Radiation resistance in mice increased following chronic application of Li2CO3

    International Nuclear Information System (INIS)

    In experiments on strain H mice the increased radiation resistance of mice was analysed after three weeks' feeding with a diet including Li given as lithium carbonicum. The concentration of Li in the serum during the first three days of feeding was increased to 0.5 mmol/l and remained at that level to the end of feeding. The application of Li increased the overall number of stem cells in the spleen by 80 per cent compared with the control group. D0 of the line of dependence of the number of endogenous colonies on radiation dose increased following Li application by 1.2 Gy compared with controls. The proliferation activity of haemopoietic stem cells observed 90 min after injection of hydroxyurea was, after 21 days feeding with a mixture containing Li, increased by 200 per cent. The results support the idea that the increased radiation resistance of mice following feeding with Li salts before irradiation may be due to the increased content and resistance of the haemopoietic stem cells, as well as activation of granulopoiesis. (Auth.)

  15. Gene analysis and dynamics of tumor stem cell in human glioblastoma cells after radiation

    International Nuclear Information System (INIS)

    Because glioblastoma is the most malignant central nervous system (CNS) tumor, it is very difficult to cure despite surgery and adjuvant therapy. At present, surgery, radiotherapy, and chemotherapy are combined in the treatment of each patient. However, glioblastoma have radiotherapy and chemotherapy resistance, and this is not a radical treatment. We suspect that the tumor stem cell affects the recurrence, radiotherapy resistance and chemotherapy resistance of the tumor. Many studies suggest that tumor stem cells play an important role in tumorgenesis and tumor progression. Using human glioblastoma cell lines (T98G, A172), irradiated (0 Gy, 30 Gy, 60 Gy) glioblastoma cells were prepared under the same conditions as clinical therapy. We performed the analysis of cell proliferation rate, side population analysis by fluorescence-activated cell sorter (FACS), isolation of CD133+ cells and genetic analysis (human stem cell), using these cells. In the results of this study, the stem cell-related genes were highly expressed in the CD133+ cells compared with the CD133- cells. Therefore, it suggested that the CD133+ cells may contain tumor stem cells. In T98G, when compared to unirradiated cells and 60 Gy-irradiated cells, the cell proliferation rate for 30 Gy-irradiated cells tended to be higher, and stem cell-related genes were highly expressed in 30 Gy-irradiated CD133+ cells. In other words, in T98G, from the viewpoint of antitumor effects, the results suggest that chemotherapy may show more effect in 30 Gy-irradiated. In this genetic analysis, we suggest that CD133+ cells strongly affect tumor proliferation. In addition, CD133+ cells affect the resistance and the effect of treatments because some kind of changes occur in CD133+ cells after radiation. (author)

  16. The radiation response of cells recovering after chronic hypoxia

    International Nuclear Information System (INIS)

    Experiments were performed to study the influence of hypoxic pretreatment on the radiation response of A431 human squamous carcinoma cells. Reaeration for 10 min after chronic hypoxia (greater than 2 h) was found to enhance the radiosensitivity of A431 cells, and the maximal effect was seen for those cells reaerated after 12 h of hypoxia. The radiosensitivity enhancement for reaerated cells after 12 h of hypoxia was maximized by 5 min after the return to aerobic conditions and reached the control level by 12 h of reaeration. This enhanced radiosensitive state was characterized by a reduced shoulder region and increased slope of the radiation dose-response curve for cells in both the exponential and plateau phases of growth. There was a slight increase in the number of G1 and decrease in the number of S and G2 + M cells for both exponential- and plateau-phase cultures following 12 h hypoxic treatment. Although growth inhibition induced by 12 h of hypoxia was seen for cells in the exponential phase, there was no cell number change in the plateau-phase culture after hypoxia. Plating efficiency (PE) of cells in both growth phases was reduced by 30% after hypoxia. Furthermore, in the exponential-phase culture, the extent of reduction in PE after hypoxia was similar among cells in different phases of the cell cycle. Although S-phase cells in exponentially growing cultures were relatively more resistant to radiation than G1 and G2 + M cells, the cell age-response pattern was the same whether the cells had been aerobic or hypoxic before reaeration and irradiation. Furthermore, the enhancement ratio associated with reaeration after 12 h of hypoxia for these three subpopulations of cells was 1.3. Our results indicate that the increase in radiosensitivity due to reaeration after chronic hypoxia is unlikely to be related to the changes of cell cycle stage and growth phase during hypoxic treatment

  17. Radiation resistance radiation-defensive the ferrous aggregates in the gamma fields

    International Nuclear Information System (INIS)

    Radiation resistance of ferrous aggregates on the basis of natural of magnetite concentrates KMA in powerful torrents gamma-radiances (to 25 MGy is in-process probed. Rates of propagation of cross-section ultrasonic pressure waves, Young modulus and alteration, a mechanical strength of designed aggregates are learnt. Advantage developed RPK in comparison with traditional reactor beton is established.

  18. The myth of cell phone radiation

    OpenAIRE

    Natarajan, Vasant

    2012-01-01

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

  19. The myth of cell phone radiation

    CERN Document Server

    Natarajan, Vasant

    2012-01-01

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

  20. Development of the radiation-resistant strain of Moraxella osloensis and effect of penicillin G on its growth

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sangyong; Yun, Hyejeong; Joe, Minho [Radiation Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Kim, Dongho [Radiation Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)], E-mail: fungikim@kaeri.re.kr

    2009-07-15

    A series of repeated exposures to {gamma}-radiation with intervening outgrowth of survivors was used to develop radioresistant cultures of Moraxella osloensis that have been recognized as potential pathogenic microorganism. The D{sub 10} value of the radiation-resistant strain, 5.903{+-}0.006 kGy, was increased by four-fold compared to the parent wild-type strain, 1.637{+-}0.004 kGy. Since most strains of M. osloensis are sensitive to penicillin, we have surveyed the sensitivity of radiation-resistant strain to this antibiotic. When the optical density was monitored after the addition of penicillin G, the radioresistant strain appeared to be more resistant to only a low concentration of penicillin G (0.5 U/ml) than the parent strain. Interestingly, however, there was no apparent difference in the number of viable cells between both strains. Scanning electron microscope data showed that the resistance cells were generally larger than the parent cells, suggesting that this increase in size may cause a higher optical density of radioresistant cells. In conclusion, radiation mutation does not affect the penicillin resistance of M. osloensis.

  1. Radiation-induced autophagy promotes esophageal squamous cell carcinoma cell survival via the LKB1 pathway.

    Science.gov (United States)

    Lu, Chi; Xie, Conghua

    2016-06-01

    Radiotherapy is an important treatment modality for esophageal cancer; however, the clinical efficacy of radiotherapy is limited by tumor radioresistance. In the present study, we explored the hypothesis that radiation induces tumor cell autophagy as a cytoprotective adaptive response, which depends on liver kinase B1 (LKB1) also known as serine/threonine kinase 11 (STK11). Radiation-induced Eca-109 cell autophagy was found to be dependent on signaling through the LKB1 pathway, and autophagy inhibitors that disrupted radiation-induced Eca-109 cell autophagy increased cell cycle arrest and cell death in vitro. Inhibition of autophagy also reduced the clonogenic survival of the Eca-109 cells. When treated with radiation alone, human esophageal carcinoma xenografts showed increased LC3B and p-LKB1 expression, which was decreased by the autophagy inhibitor chloroquine. In vivo inhibition of autophagy disrupted tumor growth and increased tumor apoptosis when combined with 6 Gy of ionizing radiation. In summary, our findings elucidate a novel mechanism of resistance to radiotherapy in which radiation-induced autophagy, via the LKB1 pathway, promotes tumor cell survival. This indicates that inhibition of autophagy can serve as an adjuvant treatment to improve the curative effect of radiotherapy. PMID:27109915

  2. Genetic control of x-ray resistance in budding yeast cells

    International Nuclear Information System (INIS)

    Five x-ray-sensitive mutants were selected from 10,000 colonies arising from survivors of ultraviolet light. These were named XS5, XS6, XS7, XS8, and XS9. Mutant XS1 was donated by Nakai. These mutations affect the resistant budding cell survival component of the survival curve and, in diploids, the low-dose interdivisional cell shoulder. They are of two types: Class I, in which budding cells lack resistance; and Class II, in which budding cells show reduced resistance. When crossed with one another, they show a complex complementation pattern. Gene dosage effects are seen in XS1 heterozygotes, while budding but not between divisions. No direct correlation between radiation sensitivity, meiosis, and sporulation is observed; genes which influence radiation sensitivity do not affect meiotic recombination. A single mutation (XS1 or XS5) suppresses the shoulders of the survival curves of both budding haploid cells and diploid nonbudding cells

  3. Ethacrynic acid: a novel radiation enhancer in human carcinoma cells

    International Nuclear Information System (INIS)

    Purpose: Because agents that interfere with thiol metabolism and glutathione S-transferase (GST) functions have been shown to enhance antitumor effects of alkylating agents in vitro and in vivo, the present study was conceived on the basis that an inhibitor of GST would enhance the radiation response of some selected human carcinoma cells. Ethacrynic acid (EA) was chosen for the study because it is an effective inhibitor of GST and is a well known diuretic in humans. Methods and Materials: Experiments were carried out with well-established human tumor cells in culture growing in Eagle's minimum essential medium (MEM) supplemented with 10% fetal calf serum (FCS). Cell lines used were MCF-7, MCF-7 adriamycin resistant (AR) cells (breast carcinoma), HT-29 cells (colon carcinoma), DU-145 cells (prostate carcinoma), and U-373 cells (malignant glioma). Cell survival following the exposure of cells to drug alone, radiation alone, and a combined treatment was assayed by determining the colony-forming ability of single plated cells in culture to obtain dose-survival curves. The drug enhancement ratio was correlated with levels of GST. Results: The cytotoxicity of EA was most pronounced in MCF-7, U-373, and DU-145 cells compared to MCF-7 AR and HT-29 cells. The levels of GST activity were found to be lower in those EA-sensitive cells. A significant radiation enhancement was obtained with EA-sensitive cells exposed to nontoxic concentrations of the drug immediately before or after irradiation. The sensitizer enhancement ratio (SER) of MCF-7 cells was 1.55 with EA (20 μg/ml), while the SER of MCF-7 AR was less than 1.1. Based on five different human tumor cells, a clear inverse relationship was demonstrated between the magnitude of SER and GST levels of tumor cells prior to the combined treatment. Conclusion: The present results suggest that EA, which acts as both a reversible and irreversible inhibitor of GST activity, could significantly enhance the radiation response of

  4. Analysis of QTL for resistance to radiation in rice

    International Nuclear Information System (INIS)

    The recombinant inbred line (RIL) population derived from rice variates Zhenshan 97B/Miyang 46 and their genetic linkage maps were used to map QTLs controlling resistant to radiation. The trait was measured by the relative germination rate (RGR) and the relative surviving plant rate (RSPR) after the seeds of each line treated with γ-rays irradiation at two 350 and 550 Gy. The results indicated that the lines treated with γ-irradiation showed different performance in resistance to radiation. Under the treatment of 350 Gy, two QTLs with additive effects were detected, of which qRR (g) 81 was only significant for relative germination rate, and it had the positive additive effects from the male parent, explaining 6.53% of the total phenotypic variations. The qRR(s)2-2 was another significant one for relative surviving plant rate, whose positive effects came from the female parent,explaining 12.81% of the total phenotypic variations. Similarly, 4 QTLs were detected under irradiation dose of 550 Gy, and qRR(g)1-2 and qRR(g)8-2 were detected for relative germination rate, with positive effects coming from female and male parent,respectively,explaining 14.38% of the total variations. qRR(s)5-2 and qRR(s)10 were detected for relative surviving plant rate, with positive effects coming from the male parent, explaining 19.65% of total variations. Under different irradiation dose, 9 pairs of double QTL epistasis effects could be identified in this population. The results suggested that the expression of QTL with resistance to radiation might have relation with the irradiation dose. (authors)

  5. Development of new radiation resistant, fire-retardant cables

    International Nuclear Information System (INIS)

    For the cables for nuclear facilities, radiation resistance and fire-retardation are severely required. The authors took note of the fact that even in the existing cables for nuclear power plants, their mechanical properties are greatly degraded by the exposure to large dose (for example, 200 Mrad in PWR testing conditions), and attempted the improvement. They employed a new additive, bromated acenaphthylene condensate (con-BACN), which effectively gives radiation resistance and also is a good flame retarder, to be compounded to an insulation material, and examined the characteristics. In this paper, the features of con-BACN and the investigation of fire-retardant EPDM composition are described. As an initial composition, a small amount of zinc white, sulphur, stearic acid, noclac 224 (Ouchi-Shinko Chemicals, Co.), and antimony trioxide, 100 parts of tale and 45 parts of con-BACN were added to 100 parts of EPDM (propylene content 34 %, Japan Synthetic Rubber Co.). As the antiaging agent, it was decided to use phenol series No. 3 as a result of test. The fire-retardant EP rubber-composed cable was produced for trial, its insulation being fabricated, using a Furukawa's pressurized salt bath continuous vulcanizer. The tests of γ-irradiation, simulated LOCA and combustion were carried out, and the test results are reported. It was indicated that the cable resisted against high dose several times as much as 200 Mrad, and was suitable for the applications, in which the mechanical properties such as bending are required to be maintained after radiation exposure. It was also found that con-BACN was safe, and its properties of decomposition, concentration and acute toxicity were all very low. (Wakatsuki, Y.)

  6. Gamma radiation resistance of tale-polypropylene composite materials

    International Nuclear Information System (INIS)

    Samples of isostatic polypropylene mixed with 10, 20 and 30 wt.% Talc were prepared. Sample films were gamma irradiated at 10 - 300 k Gy under air. The results from DSC suggested that fine particles of Talc showed pronounced nucleating effect by increasing the rate of crystallization and thermal stability. However, Talc-filled composites did not showed radiation resistant property. Absorbance intensity of carbonyl and hydroperoxide indicated the amount of oxidative degradation were increased with increasing radiation dose but would not depend on the Talc content. Talc was found to enhance polypropylene embrittlement and to lower the mechanical properties. However at appropriate concentration of Talc and low gamma dose. It is possible to improve the mechanical properties of the composites. In the field of environmental study, Talc-filled composites of iso tactic polypropylene may be used as a degradable plastic

  7. Resistant bacteria in stem cell transplant recipients

    Directory of Open Access Journals (Sweden)

    Nucci Marcio

    2002-01-01

    Full Text Available Bacterial infections account for most infections in hematopoietic stem cell transplant recipients. While early mortality reduced dramatically with the introduction of the concept of empirical antibiotic therapy in neutropenic patients, no effect of prophylaxis on the mortality was observed in many studies. On the other hand, antibiotic prophylaxis has resulted in the emergence of resistance among bacteria. In addition, the choice of the antibiotic regimen for empirical therapy and the practices of antibiotic therapy during neutropenia may result in a significant shift in the pattern of bacterial infections. The use of quinolones and vancomycin as prophylaxis, and of carbapenems and vancomycin in the empirical antibiotic therapy, are associated with the appearance of resistant Gram-positive and Gram-negative bacteria. Therefore, hematologists must be aware of the impact of these practices on the emergence of infections due to multi-resistant pathogens, since these infections may be associated with increased mortality.

  8. Overcoming Multidrug Resistance in Cancer Stem Cells

    Directory of Open Access Journals (Sweden)

    Karobi Moitra

    2015-01-01

    Full Text Available The principle mechanism of protection of stem cells is through the expression of ATP-binding cassette (ABC transporters. These transporters serve as the guardians of the stem cell population in the body. Unfortunately these very same ABC efflux pumps afford protection to cancer stem cells in tumors, shielding them from the adverse effects of chemotherapy. A number of strategies to circumvent the function of these transporters in cancer stem cells are currently under investigation. These strategies include the development of competitive and allosteric modulators, nanoparticle mediated delivery of inhibitors, targeted transcriptional regulation of ABC transporters, miRNA mediated inhibition, and targeting of signaling pathways that modulate ABC transporters. The role of ABC transporters in cancer stem cells will be explored in this paper and strategies aimed at overcoming drug resistance caused by these particular transporters will also be discussed.

  9. Evaluation of the radiation resistance of electrical insulation materials

    International Nuclear Information System (INIS)

    The qualification of insulating materials for electrical cables is often accomplished according to the IEC 60544 standard of the International Electrotechnical Commission. The mechanical properties of the polymeric insulators are tested prior and after irradiation at relatively high dose rates. To assess the ageing of selected materials under realistic service conditions, usually at lower dose rate, an IEC Working Group has proposed extrapolation methods (IEC 61244-2), one of which is applied here for a cable sheathing material from Huber+Suhner. The method is found to be suitable to compare radiation resistance data of different materials irradiated under different conditions

  10. The resistive bolometer for radiated power measurement on EAST.

    Science.gov (United States)

    Duan, Y M; Hu, L Q; Mao, S T; Chen, K Y; Lin, S Y

    2012-09-01

    The resistive bolometer system has been successfully employed on experimental advanced superconducting tokamak for the first time to measure the radiated power of plasma. The bolometer detectors are based on 4 μm thick Pt absorbers deposited on 1.5 μm thick SiN membranes. The system consists of 3 cameras with a total of 48 channels. The detector and the system setup are described in detail. The detector calibration and typical measurement results are presented as well. PMID:23025621

  11. Host cell reactivation studies with epidermal cells of mice sensitive and resistant to carcinogenesis

    International Nuclear Information System (INIS)

    Primary epidermal cells from AKR, BALB/c, CD-1, and SENCAR mice, listed in order of least to most sensitive to epidermal carcinogenesis by initiation and promotion protocols, were found to be equally competent to ''reactivate'' herpes simplex virus type 1 irradiated by germicidal ultraviolet radiation. Nontumorigenic BALB/c epidermal cell lines selected in vitro for resistance to terminal differentiation after in vivo or in vitro treatment with initiating doses of carcinogens showed virus survival curves similar to those of primary cells. Similarly, primary cultures which were allowed to grow to confluency following a single treatment with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (100 ng/ml) retained normal host cell reactivation. Host cell reactivation studies with mouse dermal fibroblasts could not be done because of the failure of the herpes simplex virus to infect these cells and produce plaques. These results demonstrate that survival of ultraviolet light-damaged virus in primary epidermal cells in culture is unrelated to whether the cells are derived from mice sensitive or resistant to epidermal carcinogenesis. Furthermore, virus survival is not changed by tumor promoter treatment or by treatment with initiating doses of carcinogens which results in differentiation-resistant cells

  12. The essential role of the Deinococcus radiodurans ssb gene in cell survival and radiation tolerance.

    Directory of Open Access Journals (Sweden)

    J Scott Lockhart

    Full Text Available Recent evidence has implicated single-stranded DNA-binding protein (SSB expression level as an important factor in microbial radiation resistance. The genome of the extremely radiation resistant bacterium Deinococcus radiodurans contains genes for two SSB homologs: the homodimeric, canonical Ssb, encoded by the gene ssb, and a novel pentameric protein encoded by the gene ddrB. ddrB is highly induced upon exposure to radiation, and deletions result in decreased radiation-resistance, suggesting an integral role of the protein in the extreme resistance exhibited by this organism. Although expression of ssb is also induced after irradiation, Ssb is thought to be involved primarily in replication. In this study, we demonstrate that Ssb in D. radiodurans is essential for cell survival. The lethality of an ssb deletion cannot be complemented by providing ddrB in trans. In addition, the radiation-sensitive phenotype conferred by a ddrB deletion is not alleviated by providing ssb in trans. By altering expression of the ssb gene, we also show that lower levels of transcription are required for optimal growth than are necessary for high radiation resistance. When expression is reduced to that of E. coli, ionizing radiation resistance is similarly reduced. UV resistance is also decreased under low ssb transcript levels where growth is unimpaired. These results indicate that the expression of ssb is a key component of both normal cellular metabolism as well as pathways responsible for the high radiation tolerance of D. radiodurans.

  13. Resistance of human erythrocytes containing elevated levels of vitamin E to radiation-induced hemolysis

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.A.

    1983-08-01

    Human erythrocytes were isolated from the blood of healthy donors and then incubated in the presence of suspensions of ..cap alpha..-tocopherol for 30 min at 37/sup 0/C. Unabsorbed tocopherol was removed by centrifugation using several washes of isotonic phosphate-buffered saline. Washed erythrocytes were resuspended to 0.05% Hct and exposed to hemolyzing doses of /sup 60/Co gamma radiation, and hemolysis was monitored continuously by light scattering at 700 nm in a recording spectrophotometer. The extent of hemolysis with time was sigmoid and data analysis was carried out on the time taken for 50% hemolysis to occur (t/sub 50%/). The vitamin E content of erythrocytes was significantly elevated by the incubation procedure and resulted in the cells exhibiting a significantly increased resistance to hemolysis as reflected by the extended t/sub 50%/ values. Oral supplementation of 500 IU of vitamin E per day to eight normal human subjects for a period of 16 days also resulted in their washed erythrocytes exhibiting a significant increase in resistance to radiation-induced hemolysis. When comparing vitamin E incubated cells with control cells, both the dose-reducing factor (DRF) and the time for 50% hemolysis quotient (Qt/sub 50%/) were observed to increase with increasing radiation dose.

  14. Resistance of human erythrocytes containing elevated levels of vitamin E to radiation-induced hemolysis

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.A.

    1983-08-01

    Human erythrocytes were isolated from the blood of healthy donors and then incubated in the presence of suspensions of alpha-tocopherol for 30 min at 37 degrees C. Unabsorbed tocopherol was removed by centrifugation using several washes of isotonic phosphate-buffered saline. Washed erythrocytes were resuspended to 0.05%. Hct and exposed to hemolyzing doses of /sup 60/Co gamma radiation, and hemolysis was monitored continuously by light scattering at 700 nm in a recording spectrophotometer. The extent of hemolysis with time was sigmoid and data analysis was carried out on the time taken for 50% hemolysis to occur (t50%). The vitamin E content of erythrocytes was significantly elevated by the incubation procedure and resulted in the cells exhibiting a significantly increased resistance to hemolysis as reflected by the extended t50% values. Oral supplementation of 500 IU of vitamin E per day to eight normal human subjects for a period of 16 days also resulted in their washed erythrocytes exhibiting a significant increase in resistance to radiation-induced hemolysis. When comparing vitamin E incubated cells with control cells, both the dose-reducing factor (DRF) and the time for 50% hemolysis quotient (Qt50%) were observed to increase with increasing radiation dose.

  15. Resistance of human erythrocytes containing elevated levels of vitamin E to radiation-induced hemolysis

    International Nuclear Information System (INIS)

    Human erythrocytes were isolated from the blood of healthy donors and then incubated in the presence of suspensions of α-tocopherol for 30 min at 370C. Unabsorbed tocopherol was removed by centrifugation using several washes of isotonic phosphate-buffered saline. Washed erythrocytes were resuspended to 0.05% Hct and exposed to hemolyzing doses of 60Co gamma radiation, and hemolysis was monitored continuously by light scattering at 700 nm in a recording spectrophotometer. The extent of hemolysis with time was sigmoid and data analysis was carried out on the time taken for 50% hemolysis to occur (t/sub 50%/). The vitamin E content of erythrocytes was significantly elevated by the incubation procedure and resulted in the cells exhibiting a significantly increased resistance to hemolysis as reflected by the extended t/sub 50%/ values. Oral supplementation of 500 IU of vitamin E per day to eight normal human subjects for a period of 16 days also resulted in their washed erythrocytes exhibiting a significant increase in resistance to radiation-induced hemolysis. When comparing vitamin E incubated cells with control cells, both the dose-reducing factor (DRF) and the time for 50% hemolysis quotient (Qt/sub 50%/) were observed to increase with increasing radiation dose

  16. Resistance of human erythrocytes containing elevated levels of vitamin E to radiation-induced hemolysis

    International Nuclear Information System (INIS)

    Human erythrocytes were isolated from the blood of healthy donors and then incubated in the presence of suspensions of alpha-tocopherol for 30 min at 37 degrees C. Unabsorbed tocopherol was removed by centrifugation using several washes of isotonic phosphate-buffered saline. Washed erythrocytes were resuspended to 0.05%. Hct and exposed to hemolyzing doses of 60Co gamma radiation, and hemolysis was monitored continuously by light scattering at 700 nm in a recording spectrophotometer. The extent of hemolysis with time was sigmoid and data analysis was carried out on the time taken for 50% hemolysis to occur (t50%). The vitamin E content of erythrocytes was significantly elevated by the incubation procedure and resulted in the cells exhibiting a significantly increased resistance to hemolysis as reflected by the extended t50% values. Oral supplementation of 500 IU of vitamin E per day to eight normal human subjects for a period of 16 days also resulted in their washed erythrocytes exhibiting a significant increase in resistance to radiation-induced hemolysis. When comparing vitamin E incubated cells with control cells, both the dose-reducing factor (DRF) and the time for 50% hemolysis quotient (Qt50%) were observed to increase with increasing radiation dose

  17. Improvement of radiation resistance for polytetrafluoroethylene(PTFE) by radiation cross-linking

    International Nuclear Information System (INIS)

    The crosslinked polytetrafluoroethylene(PTFE) was prepared by electron beams irradiation technique in the molten state at 340degC ± 3degC in inert gas atmosphere. The crosslinking density was changed by the irradiation dose. The radiation resistance of crosslinked PTFE was investigated on the mechanical properties after irradiation by γ-rays at room temperature under vacuum and in air. The dose at half value of elongation at break was about 1MGy for 500kGy-crosslinked PTFE, while the dose for non-crosslinked PTFE was only 3.5kGy. It was found that the radiation resistance of PTFE was extremely improved by crosslinking. (author)

  18. Heightening of radiation resistance of plastics for medical use

    International Nuclear Information System (INIS)

    There are high pressure steam process, ethylene oxide gas process and Co-60 gamma ray irradiation for the sterilization of medical appliances. At present, ethylene oxide gas process is the main method, but there are the problems of residual gas and the unsterilized parts in the appliances of complex shapes. Also the residual gas concentration in working environment is strictly regulated because of its toxicity, therefore, the change to Co-60 gamma ray or electron beam sterilization is considered. In this paper, the examination on the additives for improving the radiation resistance of the polypropylene and polyvinyl chloride used for medical appliances is reported. Polypropylene is used most as the material for medical appliances in Japan. Under the irradiation condition in the air, it causes decay at 2.5 Mrad, and the physical properties begin to lower. As the result of experiments, monoalkyl diphenyl ether has the effect of heightening the radiation resistance of polypropylene. Polyvinyl chloride is excellent in its workability, and is cheap, therefore, it is used for various medical appliances. However, it causes coloring by gamma ray sterilization. As the result of experiment, the addition of monoalkyl diphenyl ether suppressed the oxidation of polyvinyl chloride, therefore even after one year, the effect of its addition was observed. (K.I.)

  19. 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

  20. Transfer of innate resistance and susceptibility to Leishmania donovani infection in mouse radiation bone marrow chimaeras

    Energy Technology Data Exchange (ETDEWEB)

    Crocker, P.R.; Blackwell, J.M.; Bradley, D.J. (London School of Hygiene and Tropical Medicine (UK))

    1984-07-01

    Reciprocal radiation bone marrow chimaeras were made between H-2-compatible strains of mice innately resistant or susceptible to visceral leishmaniasis. In initial experiments, susceptibility but not resistance to Leishmania donovani could be transferred with donor bone marrow into irradiated recipients. In subsequent experiments it was possible to transfer both resistance and susceptibility. This was achieved either by selecting more radiosensitive mouse strains as susceptible recipients, or alternatively by increasing the irradiation dose for the susceptible recipients used in the initial experiments. Using the higher irradiation dose, successful transfer of resistance and susceptibility between congenic mice carrying the Lshsup(r) and Lshsup(s) alleles on the more radioresistant B10 genetic background provided firm evidence that the results obtained in this study were specifically related to expression of the Lsh gene. It is concluded that Lsh gene-controlled resistance and susceptibility to L. donovani is determined by bone marrow-derived cells. The cell type(s) involved is likely to be of the macrophage lineage.

  1. Transfer of innate resistance and susceptibility to Leishmania donovani infection in mouse radiation bone marrow chimaeras

    International Nuclear Information System (INIS)

    Reciprocal radiation bone marrow chimaeras mere made between H-2-compatible strains of mice innately resistant or susceptible to visceral leishmaniasis. In initial experiments, susceptibility but not resistance to Leishmania donovani could be transferred with donor bone marrow into irradiated recipients. In subsequent experiments it was possible to transfer both resistance and susceptibility. This was achieved either by selecting more radiosensitive mouse strains as susceptible recipients, or alternatively by increasing the irradiation dose for the susceptible recipients used in the initial experiments. Using the higher irradiation dose, successful transfer of resistance and susceptibility between congenic mice carrying the Lshsup(r) and Lshsup(s) alleles on the more radioresistant B10 genetic background provided firm evidence that the results obtained in this study were specifically related to expression of the Lsh gene. It is concluded that Lsh gene-controlled resistance and susceptibility to L. donovani is determined by bone marrow-derived cells. The cell type(s) involved is likely to be of the macrophage lineage. (author)

  2. Radiation hardening of InP solar cells for space applications

    International Nuclear Information System (INIS)

    The aim of this work is to develop a radiation resistant thin InP-based solar cells for space applications on more mechanically resistant, lighter, and cheaper substrates. In this paper, we present the development of a p+/nn+ InP-based solar cell structures with very thin emitter and base layers. A thin emitter helps to increase the collection of carriers generated by high energy incident photons from the solar spectrum. The use of a thin n base structure should improve the radiation resistance of this already radiation resistant technology. A remarkable improvement of high energy photons response is shown for InP solar cells with emitters 400 A thick

  3. Radiation resistance of epoxy resins and their composistes

    International Nuclear Information System (INIS)

    In the electric equipment installed inside containment vessels in nuclear power plants, many epoxy resins have been employed as insulating materials. However, there are very few reports on the investigation of their properties in such environment, specifically under LOCA (Loss-of-Coolant Accident) conditions. This paper investigates on the electrical and mechanical properties of the epoxy resins supposed to be applicable to the actual equipment, by LOCA simulation. The epoxy resins used for the experiment were the following three types: (1) typical epoxy resin, bisphenol A group; (2) novolak group epoxy resins in consideration of improving humidity resistance; and (3) triazine group epoxy resins for the purpose of giving radiation, humidity and heat resistances. The last one includes the composites with Nomex and with laminated mica. After LOCA simulation which is composed of up to 2 MGy irradiation of 60Co γ-ray at the dose rate of 104 Gy/h and the exposure to high temperature saturated steam, the electrical properties of dielectric tangent, insulation breakdown voltage (BDV) and conductivity and the mechanical properties of bending strength and viscoelasticity were measured. In the paper, the experimental results are described in detail. Of these, the triazine group epoxy/Nomex composite did not show swelling, but demonstrated stable radiation resistance. It is excellent in the electrical and mechanical properties, and also shows good dimension-stability. In LOCA simulation, its bending strength was reduced than that for only γ-irradiation of 2 MGy, but still had the residual strength of about 80 %. (Wakatsuki, Y.)

  4. Radiation resistance of paralytic shellfish poison (PSP) toxins

    International Nuclear Information System (INIS)

    Radiation resistance of paralytic shellfish poison (PSP) toxins, obtained from Pyrodinium bahamense var. compressum in shellstocks of green mussels, was determined by subjecting the semi-purified toxin extract as well as the shellstocks of green mussels to high doses of ionizing radiation of 5, 10, 15 and 20 kGy. The concentration of the PSP toxins was determined by the Standard Mouse Bioassay (SMB) method. The radiation assistance of the toxins was determined by plotting the PSP toxin concentration versus applied dose in a semilog paper. The D10 value or decimal reduction dose was obtained from the straight line which is the dose required to reduce the toxicity level by 90%. The effects of irradiation on the quality of green mussels in terms of its physico-chemical, microbiological and sensory attributes were also conducted. The effect of irradiation on the fatty acid components of green mussels was determined by gas chromatography. Radiation resistance of the PSP toxins was determined to be lower in samples with initially high toxicity level as compared with samples with initially low toxicity level. The D10 values of samples with initially high PSP level were 28.5 kGy in shellstocks of green musssels and 17.5 kGy in the semi-purified toxin extract. When the PSP level was low initially, the D10 values were as high as 57.5 and 43.5 kGy in shellstocks of green mussels for the two trials, and 43.0 kGy in semi-purified toxin extract. The microbial load of the irradiated mussels was remarkably reduced. No differnce in color and odor characteristics were observed in the mussel samples subjected to varying doses of ionizing radiation. There was darkening in the color of mussel meat and its juice. The concentration of the fatty acid components in the fresh green mussels were considerably higher as compared with those present in the irradiated mussels, though some volatile fatty acids were detected as a result of irradiation. (Author)

  5. Design of radiation resistant metallic multilayers for advanced nuclear systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhernenkov, Mikhail, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Gill, Simerjeet, E-mail: zherne@bnl.gov, E-mail: gills@bnl.gov; Stanic, Vesna; DiMasi, Elaine; Kisslinger, Kim; Ecker, Lynne [Brookhaven National Laboratory, Upton, New York 11973 (United States); Baldwin, J. Kevin; Misra, Amit [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Demkowicz, M. J. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2014-06-16

    Helium implantation from transmutation reactions is a major cause of embrittlement and dimensional instability of structural components in nuclear energy systems. Development of novel materials with improved radiation resistance, which is of the utmost importance for progress in nuclear energy, requires guidelines to arrive at favorable parameters more efficiently. Here, we present a methodology that can be used for the design of radiation tolerant materials. We used synchrotron X-ray reflectivity to nondestructively study radiation effects at buried interfaces and measure swelling induced by He implantation in Cu/Nb multilayers. The results, supported by transmission electron microscopy, show a direct correlation between reduced swelling in nanoscale multilayers and increased interface area per unit volume, consistent with helium storage in Cu/Nb interfaces in forms that minimize dimensional changes. In addition, for Cu/Nb layers, a linear relationship is demonstrated between the measured depth-dependent swelling and implanted He density from simulations, making the reflectivity technique a powerful tool for heuristic material design.

  6. The radiation effects on the living cell

    International Nuclear Information System (INIS)

    This publication is a presentation of particular points discussed during the colloquium of the 15-18 june 1999, for which scientific researches are performed at the CEA/CNRS. They deal with the radiobiology, for the radiation effects on living matter; with the DNA, for the knowledge and repair mechanisms on cells submitted to ionizing radiations; with the exposition to UV in correlation with neoplasms; with the P53 gene which is a tumour suppressor. (A.L.B.)

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

    International Nuclear Information System (INIS)

    Radical scavenging system for reactive oxygen species (ROS) leading to radio-protection is reviewed on findings in animals, tissues and cells. Protection against oxygen toxicity in evolution can be seen in anaerobes' superoxide dismutase (SOD) over 3500 million years ago. ROS is generated endogenously and also by radiation. However, the intracellular sites of the generated ROS are different depending on its cause. The protection is done through enzymes like SOD, peroxidase, catalase, glutathione-related enzymes and through substances like GSH, α-tocopherol, ascorbic acid etc. Induction of ROS scavenging substances related with radio-resistance includes the responses to the low dose radiation (5-50 cGy) in those enzymes described above; to middle to high dose radiation (1-30 Gy) in a similar and in other unknown mechanisms; to exposure of ROS like H2O2 at low concentration; and to antioxidant treatment. The cross-resistance between radiation and drugs suggests necessity of this induction. (N.I.)

  8. Radiation Resistant Hybrid Lotus Effect Photoelectrocatalytic Self-Cleaning Anti-Contamination Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop radiation resistant hybrid Lotus Effect photoelectrocatalytic self-cleaning anti-contamination coatings for application to Lunar...

  9. Adult Mesenchymal Stem Cells and Radiation Injury.

    Science.gov (United States)

    Kiang, Juliann G

    2016-08-01

    Recent understanding of the cellular and molecular signaling activations in adult mesenchymal stem cells (MSCs) has provided new insights into their potential clinical applications, particularly for tissue repair and regeneration. This review focuses on these advances, specifically in the context of self-renewal for tissue repair and recovery after radiation injury. Thus far, MSCs have been characterized extensively and shown to be useful in mitigation and therapy for acute radiation syndrome and cognitive dysfunction. Use of MSCs for treating radiation injury alone or in combination with additional trauma is foreseeable. PMID:27356065

  10. 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)

  11. Protein disulphide isomerase as a target for nanoparticle-mediated sensitisation of cancer cells to radiation

    OpenAIRE

    Taggart, L E; McMahon, S. J.; Butterworth, K T; Currell, F. J.; Schettino, G; Prise, K. M.

    2016-01-01

    Radiation resistance and toxicity in normal tissues are limiting factors in the efficacy of radiotherapy. Gold nanoparticles (GNPs) have been shown to be effective at enhancing radiation-induced cell death, and were initially proposed to physically enhance the radiation dose deposited. However, biological responses of GNP radiosensitization based on physical assumptions alone are not predictive of radiosensitisation and therefore there is a fundamental research need to determine biological me...

  12. Human genetic marker for resistance to radiations and chemicals. 1998 annual progress report

    International Nuclear Information System (INIS)

    'The broad objective of the project is to understand the molecular basis for the response of cells to radiations and chemicals, with the pragmatic goal of being able to identify human subpopulations that are exceptionally sensitive to DNA damaging agents. The project focuses on HRAD9, a human orthologue of the fission yeast Schizosaccharomyces pombe gene rad9. S. pombe rad9::ura4+ mutant cells are highly sensitive to ionizing radiation, UV and many chemicals, such as the DNA synthesis inhibitor hydroxyurea. They also lack the ability to delay cycling transiently in S phase or in G2 following a block in DNA replication or after incurring DNA damage, respectively -i.e., they lack checkpoint controls. The attempt by mutant cells to progress through mitosis in the absence of fully intact DNA accounts at least in part for their sensitivity to DNA damaging agents. Cells bearing rad9::ura4+ also aberrantly regulate UVDE, an enzyme that participates in a secondary DNA excision repair pathway. The key role played by S. pombe rad9 in promoting resistance to chemicals and radiations suggests that the evolutionarily conserved human cognate also has important functions in mammals. The first set of aims in this proposal centers on characterizing the structure and expression of HRAD9, to assess structure/function relationships and potentially link protein activity to a specific tissue. The next set of aims focuses on determining the role of HRAD9 in radio/chemoresponsiveness and cancer.'

  13. Radiation response characteristics of human cell in vitro

    International Nuclear Information System (INIS)

    Improvements in tissue culture techniques and growth media have made it possible to culture a range of cells of human origin, both normal and malignant. The most recent addition to the list are endothelial cells. Interesting results have been obtained, some of which may have implications in Radiation Therapy. (i) Repair of Potentially Lethal Damage (PLDR) has been observed in all cell lines investigated; cells of normal origin repair PLD at least as well as malignant cells, which makes clinical trials of PLDR inhibitors of doubtful usefulness. (ii) PLD in fibroblasts of human origin appears to have a component that is repaired rapidly, in a matter of minutes, as well as a slower component that takes hours to repair. (iii) Sublethal damage repair, manifest by a dose-rate effect, has also been observed in all human cell lines tested. Cells of normal tissue origin, including fibroblasts and endothelial cells, exhibit a dose-rate effect that is intermediate between that for cells from traditionally resistant tumors (melanoma and osteosarcoma) and cells from more sensitive tumors (neuroblastoma and breast). (iv) Fibroblasts from patients with Ataxia Telangectasia (AT) are much more sensitive to x-rays, with a D/sub o/ about half that for normal human fibroblasts. Nevertheless repair of both PLD and SLD can be demonstrated in these cells

  14. Prototype of a radiation hard resistive bolometer for ITER

    International Nuclear Information System (INIS)

    The prototype of a radiation hard resistive bolometer has been produced. This prototype bolometer was installed in ASDEX Upgrade to test its viability and long term stability in a tokamak environment. The prototype bolometer with platinum meanders and absorber on an amorphous silicon nitride substrate and the original standard Kapton bolometer used on ASDEX Upgrade and JET with gold meanders and absorber were calibrated as a function of temperature. The temperature coefficients of the gold and platinum meander resistances are found to have the same value to within 5%. Heat diffusion simulations of the bolometer foils, using the dimensions, specific heat, density and thermal conductivity of the components, were carried out to calculate the cooling time constant and heat capacity of the foils. These calculated values are in agreement with those measured to within 15%. In accordance with these simulations, the prototype bolometer is a factor of 2 more sensitive than the original bolometer and the cooling time constant of the prototype was about a factor of 2 smaller than the original bolometer. The design considerations involved in producing this bolometer foil are discussed and recommendations for future development work are outlined

  15. Radiation- induced aneuploidy in mammalian germ cells

    International Nuclear Information System (INIS)

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

  16. Development of bio-selective strategies to radio-resistant tumor cells

    International Nuclear Information System (INIS)

    Radiotherapy is one of the established treatments for solid tumors. Investigation of tumor radioresistance is important for future tumor radiotherapy. Biological bases on the resistance have not been fully understood. Recent studies have demonstrated that there is a small fraction in solid tumor which is highly resistant to ionizing radiation and the radioresistant tumor cells often expressed some stem cell markers. Resistance of tumors to both radiation and chemotherapeutic agents can be attributed to the features of the cancer stem cells. In the present study, we show that a human glioblastoma cell line A172 transiently becomes to ''stem cell-like appearance'' when cultured with non-serum media supplemented with the growth factors. The treated cells were found significantly resistant to X-rays compared with the cells cultured in normal media. Phosphorylation of histon H2Ax was induced in both forms, however, stem cell-like cells contained subpopulation which is more registant to IR than the parental A172 cells. Our result is consistent with the hypothesis that cancer stemness contribute to the radioresistance probably by their efficient repair activity on DNA double-strand breaks. (author)

  17. Investigation of possibility of creation of radiation resistance sensors for physical information based on fiber materials

    Science.gov (United States)

    Baskov, P. B.; Chebyshov, S. B.; Kadilin, V. V.; Sakharov, V. V.; Mosyagina, I. V.

    2016-02-01

    The results of physical and material science and technological development of new materials of radiation photonics - nano- and microstructure of radiation-sensitive and radiation- resistant optical glass and fibers based on quartz are presented in the report. The possibility of their application in neutron diagnostics devices of nuclear power objects are considered. Component and construction options for the radiation-sensitive fiber and glass materials (with isotopes 10B, 6Li, Gd, ions of Nd3+, Ce3+ etc.), in which radiation resistance is achieved through the organization of areas of "drain" and annihilation of radiation-induced defects are considered.

  18. Radiation effects in mammalian cells in vitro

    International Nuclear Information System (INIS)

    The purpose of this research effort is to elucidate the mechanisms for the radiation-induced changes in mammalian cells that lead to cell death, mutation, neoplastic transformation, DNA damage, and chromosomal alterations. Of particular interest are the effects of low-dose-rate and fractionated irradiation on these end points with respect to the mechanisms whereby these effects are influenced by cellular repair processes, inhibitors, and promoters that act at the genetic or biochemical level. 17 refs

  19. Radiation therapy for intracranial germ cell tumor

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Wakako; Takizawa, Yoshikazu; Yoshida, Hiroshi; Aruga, Moriyo; Arimizu, Noboru (Chiba Univ. (Japan). School of Medicine); Itami, Jun

    1993-05-01

    From 1974 through 1988, 27 patients with intracranial germ cell tumor underwent radiotherapy in Chiba University Hospital. Radiation field encompassed the whole neuroaxis in 19 patients, the local area in 5, and the whole brain in 3. Overall 5-year survival rate of all 27 patients was 88.9%. There was no significant difference in 5-year overall survival rate between the patients who were treated by the neuroaxis radiation and by the more limited fields. The most significant prognostic factor was pathology of the tumors. Germinoma and histology-unknown tumors which showed good response to irradiation have more favorable prognosis than embryonal carcinoma and choriocarcinoma. From our data, three possibilities emerged: (1) some germinomas might be controlled by localized radiation; (2) optimal dose might be 45[approx]50 Gy; (3) if histology-unknown tumor has good response to radiation at 20 Gy, the tumor can be treated by the same way as germinoma. (author).

  20. Phorbol esters induce multidrug resistance in human breast cancer cells

    International Nuclear Information System (INIS)

    Mechanisms responsible for broad-based resistance to antitumor drugs derived from natural products (multidrug resistance) are incompletely understood. Agents known to reverse the multidrug-resistant phenotype (verapamil and trifluoperazine) can also inhibit the activity of protein kinase C. When the authors assayed human breast cancer cell lines for protein kinase C activity, they found that enzyme activity was 7-fold higher in the multidrug-resistance cancer cells compared with the control, sensitive parent cells. Exposure of drug-sensitive cells to the phorbol ester phorbol 12,13-dibutyate [P(BtO)2] led to an increase in protein kinase C activity and induced a drug-resistance phenotype, whereas exposure of drug-resistant cells to P(BtO)2 further increased drug resistance. In sensitive cells, this increased resistance was accomplished by a 3.5-fold increased phosphorylation of a 20-kDa particulate protein and a 35-40% decreased intracellular accumulation of doxorubicin and vincristine. P(BtO)2 induced resistance to agents involved in the multidrug-resistant phenotype (doxorubicin and vincristine) but did not affect sensitivity to an unrelated alkylating agent (melphalan). The increased resistance was partially or fully reversible by the calcium channel blocker verapamil and by the calmodulin-antagonist trifluoperazine. These data suggest that stimulation of protein kinase C playus a role in the drug-transport changes in multidrug-resistant cells. This may occur through modulation of an efflux pump by protein phosphorylation

  1. Differences in radiation-induced micronuclei yields of human cells: influence of ras gene expression and protein localization

    International Nuclear Information System (INIS)

    Expression of ras on cogene has been correlated with increased intrinsic resistance to ionizing radiation. In this study the authors show that increased EJras expression in human cells is associated with a decrease in the frequency of radiation-induced micronuclei. The experimental system consisted of human osteosarcoma-derived cell lines which quantitatively vary in their EJras expression. There was a dose-dependent relationship between radiation dose and micronuclei formation in all cell lines tested. (author)

  2. Development of new radiation resistant, fire-retardant cables. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hagiwara, Ko; Morita, Yosuke; Udagawa, Takashi (Japan Atomic Energy Research Inst., Takasaki, Gunma. Takasaki Radiation Chemistry Research Establishment); Fujimura, Shun-ichi; Oda, Eisuke

    1982-12-01

    For the cables for nuclear facilities, radiation resistance and fire-retardation are severely required. The authors took note of the fact that even in the existing cables for nuclear power plants, their mechanical properties are greatly degraded by the exposure to large dose (for example, 200 Mrad in PWR testing conditions), and attempted the improvement. They employed a new additive, bromated acenaphthylene condensate (con-BACN), which effectively gives radiation resistance and also is a good flame retarder, to be compounded to an insulation material, and examined the characteristics. In this paper, the features of con-BACN and the investigation of fire-retardant EPDM composition are described. As an initial composition, a small amount of zinc white, sulphur, stearic acid, noclac 224 (Ouchi-Shinko Chemicals, Co.), and antimony trioxide, 100 parts of tale and 45 parts of con-BACN were added to 100 parts of EPDM (propylene content 34 %, Japan Synthetic Rubber Co.). As the antiaging agent, it was decided to use phenol series No. 3 as a result of test. The fire-retardant EP rubber-composed cable was produced for trial, its insulation being fabricated, using a Furukawa's pressurized salt bath continuous vulcanizer. The tests of ..gamma..-irradiation, simulated LOCA and combustion were carried out, and the test results are reported. It was indicated that the cable resisted against high dose several times as much as 200 Mrad, and was suitable for the applications, in which the mechanical properties such as bending are required to be maintained after radiation exposure. It was also found that con-BACN was safe, and its properties of decomposition, concentration and acute toxicity were all very low.

  3. Increase of radiation resistance of a soil microflora exposed to long-term gamma irradiation

    International Nuclear Information System (INIS)

    Soil microflora were exposed to long-term (18 months) gamma irradiation in an open-air facility at three different doses, 15, 150, and 1500 krads/18 months. The radiation resistance increased at all doses when compared with the radiation resistance of the microflora from soil shielded from the irradiation with a lead wall

  4. Modification of cellular radiosensitivity by the extracellular concentration of hydrogen ions - a possible explanation of the radiation resistance of brain tumours

    International Nuclear Information System (INIS)

    Brain tumours show a much higher local relapse frequency than other tumours after radiologic treatment. Influences of the extracellular environment on the radiation sensitivity of glioblastoma cells were examined in vitro. The results indicate that the low pH-value in the tumour might contribute to the radiation resistence. (orig.)

  5. The effect of cellular carotenoid levels in micrococcus luteus on resistance to gamma radiation

    International Nuclear Information System (INIS)

    In the present study, a biological system was developed to link the cellular carotenoid levels to Gamma radiation resistance in bacteria for the frst time. thus, in a non-photosynrhetic bacterium, in Micrococcus Luteus an inverse relationship was found between the increase in diphenylamine (DPA) concentration (5.25 μg/ml culture) and the polar cellular carotenoid pigments (C-45 and C-50 carotenoids and their glucosides). It was also found that irradiation of cells with different carotenoid concentrations with doses of γ-radiation in the range of (0.2500 gray) under oxic, air and hypoxic conditions showed that carotenoid pigments offer no significant protection as they usually do in case of visible light. (author).15 refs., 5 figs., 3 tabs

  6. Radiation response of human hematopoietic cells

    International Nuclear Information System (INIS)

    The radiosensitivity and capacity to accumulate and repair sub-lethal damage has been studied in hematopoietic cell lines of human origin and in stem cells derived from blood and bone narrow of normal human donors. The results were analysed in terms of the linear quadratic and multitarget models. For the cell lines intrinsic radiosensitivity varied widely with D/sub o/'s ranging from 0.53 to 1.39 Gy. Five of the cell lines showed same capacity to accumulate sub-lethal damage and in three of these survival was enhanced by dose fractionation or reduction of dose rate. Among the cell lines of leukemic origin, several did not conform in one or more respects with the highly radiosensitive and repair deficient model associated with hematopoietic cells. There was no apparent correlation between radiation response and the phenotype (myeloid, lymphoid or undifferentiated) of the cell lines studied. Variability of radiation response and in some cases an unpredicted degree of radioresistance and capacity to repair sub-lethal damage has now been demonstrated for both cultured and primary explants of human leukemic cells. These observations have implications for the design of Total Body Irradiation protocols for use prior to bone narrow transplant

  7. Radiation-resistant bacteria and their application to metal and radionuclides bioremediation

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-Long

    2004-01-01

    Microorganisms have a number of applications in the nuclear industry, which would benefit from the use of radiation-resistant microorganisms. Environmentally isolated bacteria have shown to be resistant to gamma irradiation up to a dose of 30,000 Gy. It has also been reported that the presence of ionizing radiation may induce radio-resistance in bacteria. Recent demonstrations of the removal and immobilization of inorganic contaminants by microbial transformations, sorption and mineralization show the potential of both natural and engineered microorganisms as bioremedial tools. This review is to provide an overview of the application of radiation-resistant bacteria to decontamination of metal and radionuclide.

  8. Radiation-resistant bacteria and their application to metal and radionuclides bioremediation

    International Nuclear Information System (INIS)

    Microorganisms have a number of applications in the nuclear industry, which would benefit from the use of radiation-resistant microorganisms. Environmentally isolated bacteria have shown to be resistant to gamma irradiation up to a dose of 30,000 Gy. It has also been reported that the presence of ionizing radiation may induce radio-resistance in bacteria. Recent demonstrations of the removal and immobilization of inorganic contaminants by microbial transformations, sorption and mineralization show the potential of both natural and engineered microorganisms as bioremedial tools. This review is to provide an overview of the application of radiation-resistant bacteria to decontamination of metal and radionuclide. (authors)

  9. 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...

  10. Transient elevation of glycolysis confers radio-resistance by facilitating DNA repair in cells

    International Nuclear Information System (INIS)

    Cancer cells exhibit increased glycolysis for ATP production (the Warburg effect) and macromolecular biosynthesis; it is also linked with therapeutic resistance that is generally associated with compromised respiratory metabolism. Molecular mechanisms underlying radio-resistance linked to elevated glycolysis remain incompletely understood. We stimulated glycolysis using mitochondrial respiratory modifiers (MRMs viz. di-nitro phenol, DNP; Photosan-3, PS3; Methylene blue, MB) in established human cell lines (HEK293, BMG-1 and OCT-1). Glucose utilization and lactate production, levels of glucose transporters and glycolytic enzymes were investigated as indices of glycolysis. Clonogenic survival, DNA repair and cytogenetic damage were studied as parameters of radiation response. MRMs induced the glycolysis by enhancing the levels of two important regulators of glucose metabolism GLUT-1 and HK-II and resulted in 2 fold increase in glucose consumption and lactate production. This increase in glycolysis resulted in resistance against radiation-induced cell death (clonogenic survival) in different cell lines at an absorbed dose of 5 Gy. Inhibition of glucose uptake and glycolysis (using fasentin, 2-deoxy-D-glucose and 3-bromopyruvate) in DNP treated cells failed to increase the clonogenic survival of irradiated cells, suggesting that radio-resistance linked to inhibition of mitochondrial respiration is glycolysis dependent. Elevated glycolysis also facilitated rejoining of radiation-induced DNA strand breaks by activating both non-homologous end joining (NHEJ) and homologous recombination (HR) pathways of DNA double strand break repair leading to a reduction in radiation-induced cytogenetic damage (micronuclei formation) in these cells. These findings suggest that enhanced glycolysis generally observed in cancer cells may be responsible for the radio-resistance, partly by enhancing the repair of DNA damage

  11. Radiation-resistance of polyurethane pipes for cooling liquid in BES III

    International Nuclear Information System (INIS)

    Gamma ray radiation and neutron radiation are predominant in the working conditions of BES III, and the radiation-resistance aging of polyurethane pipes is very important in this condition, as the pipes of cooling liquid for beam pipe and SCQ (superconducting quadrupole) vacuum pipe in BESIII. Polyester polyurethane pipes and polyether polyurethane pipes were irradiated by gamma ray and neutron. The radiation doses were as much as ten years' doses in BES. Pressure test, FTIR and thermal analysis were used to study the radiation-resistance of these two kinds of polyurethane pipes. The results show that the radiation-resistance and thermal stability of polyester polyurethane pipes are prior to those of polyether polyurethane pipes, and the pressure resistance of polyester polyurethane pipes is almost maintained after the irradiation by gamma ray and neutron, but the polyether polyurethane pipes can be aged and ruptured after the irradiation by neutron. (authors)

  12. Radiation damage in InP single crystals and solar cells

    International Nuclear Information System (INIS)

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

  13. GaAs quantum dot solar cell under concentrated radiation

    International Nuclear Information System (INIS)

    Effects of concentrated solar radiation on photovoltaic performance are investigated in well-developed GaAs quantum dot (QD) solar cells with 1-Sun efficiencies of 18%–19%. In these devices, the conversion processes are enhanced by nanoscale potential barriers and/or AlGaAs atomically thin barriers around QDs, which prevent photoelectron capture to QDs. Under concentrated radiation, the short circuit current increases proportionally to the concentration and the open circuit voltage shows the logarithmic increase. In the range up to hundred Suns, the contributions of QDs to the photocurrent are proportional to the light concentration. The ideality factors of 1.1–1.3 found from the VOC-Sun characteristics demonstrate effective suppression of recombination processes in barrier-separated QDs. The conversion efficiency shows the wide maximum in the range of 40–90 Suns and reaches 21.6%. Detailed analysis of I-V-Sun characteristics shows that at low intensities, the series resistance decreases inversely proportional to the concentration and, at ∼40 Suns, reaches the plateau determined mainly by the front contact resistance. Improvement of contact resistance would increase efficiency to above 24% at thousand Suns

  14. GaAs quantum dot solar cell under concentrated radiation

    Science.gov (United States)

    Sablon, K.; Li, Y.; Vagidov, N.; Mitin, V.; Little, J. W.; Hier, H.; Sergeev, A.

    2015-08-01

    Effects of concentrated solar radiation on photovoltaic performance are investigated in well-developed GaAs quantum dot (QD) solar cells with 1-Sun efficiencies of 18%-19%. In these devices, the conversion processes are enhanced by nanoscale potential barriers and/or AlGaAs atomically thin barriers around QDs, which prevent photoelectron capture to QDs. Under concentrated radiation, the short circuit current increases proportionally to the concentration and the open circuit voltage shows the logarithmic increase. In the range up to hundred Suns, the contributions of QDs to the photocurrent are proportional to the light concentration. The ideality factors of 1.1-1.3 found from the VOC-Sun characteristics demonstrate effective suppression of recombination processes in barrier-separated QDs. The conversion efficiency shows the wide maximum in the range of 40-90 Suns and reaches 21.6%. Detailed analysis of I-V-Sun characteristics shows that at low intensities, the series resistance decreases inversely proportional to the concentration and, at ˜40 Suns, reaches the plateau determined mainly by the front contact resistance. Improvement of contact resistance would increase efficiency to above 24% at thousand Suns.

  15. Gamma radiation resistant Fabry-Perot fiber optic sensors

    Science.gov (United States)

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

    2002-08-01

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

  16. Negative differential resistance devices for generation of terahertz radiation

    Science.gov (United States)

    Eisele, H.

    2015-08-01

    This paper discusses the principles of operation, state of the art, and future potential of active two-terminal devices for generation of low-noise, continuous-wave terahertz radiation. These devices use transit-time, transferred-electron, and quantum-mechanical effects (or a combination of them) to create a negative differential resistance (NDR) at the frequency of interest. Many different types of NDR devices have been proposed since the earliest days of semiconductor devices and studied in detailed simulations for their power generation potential, but have yet to be demonstrated experimentally. The paper focuses on NDR devices that not only yielded significant output powers at millimeter waves frequencies and higher, but also have the strong potential of generating radiation at terahertz frequencies. Examples of such NDR devices are resonant tunneling diodes (RTDs), superlattice electronic devices (SLEDs), and InP Gunn devices. Examples of their state-of-the-art results are output powers of 0.2 mW at 443 GHz and 5 μW at 1.53 THz from InGaAs/AlAs double barrier RTDs on InP substrate; 5.0 mW at 123.3 GHz, 1.1 mW at 155.1 GHz, and 0.52 mW at 252.8 GHz from GaAs/AlAs superlattice electronic devices on GaAs substrate; and 330 μW at 412 GHz, 86 μW at 479 GHz, and 18 μW at 502 GHz from InP Gunn devices.

  17. Quiescent cells: A natural way to resist chemotherapy

    Science.gov (United States)

    Menchón, S. A.; Condat, C. A.

    2011-10-01

    Most chemotherapeutic treatments use drugs that target proliferating cancer cells. Therefore, they do not affect quiescent cells which are naturally resistant. Surviving cancer cells can reactivate their cell cycles in the intervals between doses, becoming proliferative again and thus restarting tumor growth. In this work, we present a mathematical model to study the impact of quiescent cells on chemotherapy effectiveness. Our simulations show that, although tumor growth is delayed after the beginning of each dose, the resistance of quiescent cells is enough to reactivate it due to accelerated repopulation, eventually causing therapy failure even in the absence of acquired resistance.

  18. /TiN Resistive RAM (RRAM) Cells

    Science.gov (United States)

    Chen, Z. X.; Fang, Z.; Wang, Y.; Yang, Y.; Kamath, A.; Wang, X. P.; Singh, N.; Lo, G.-Q.; Kwong, D.-L.; Wu, Y. H.

    2014-11-01

    We present a study of Ni silicide as the bottom electrode in HfO2-based resistive random-access memory cells. Various silicidation conditions were used for each device, yielding different Ni concentrations within the electrode. A higher concentration of Ni in the bottom electrode was found to cause a parasitic SET operation during certain RESET operation cycles, being attributed to field-assisted Ni cation migration creating a Ni filament. As such, the RESET is affected unless an appropriate RESET voltage is used. Bottom electrodes with lower concentrations of Ni were able to switch at ultralow currents (RESET current <1 nA) by using a low compliance current (<500 nA). The low current is attributed to the tunneling barrier formed by the native SiO2 at the Ni silicide/HfO2 interface.

  19. Radiation resistance of microorganisms comprising the bioburden of operating room packs

    International Nuclear Information System (INIS)

    Experiments were undertaken to determine the radiation resistance of 673 isolates obtained from the culture of surgical pack materials which had been exposed to gamma-radiation doses of 0.2 to 0.8 Mrad, using a screen test employing radiation doses of 1.0, 1.5 and 2.0 Mrad. The methods and materials are described. The D10 of radiation resistant microorganisms was determined more closely, since they would need significantly greater radiation dosage to be reduced to an acceptable probability of survival. Results are analyzed and discussed. (U.K.)

  20. Radiation protection measures for hot cell sanitation

    International Nuclear Information System (INIS)

    The cell 5 of the Hot Cell Facility of the Kernforschungszentrum Karlsruhe GmbH (KfK) was to be restored and reequipped after 12 years of operation. The decontamination work was first done remotely controlled and afterwards by 38 persons entering the cell, which took about 2 months. The radiation protection methods and personal dosimetry systems are described. At the beginning of the work the γ-dose rate amounted up to 900 mSv/h. After completion of the remotely controlled decontamination work the γ-dose rate decreased to 1.5 mSv/h. At that time the (α+β-contamination was 105 Bq/cm2. Till the end of the work the removable activity dropped to 102 - 103 Bq/cm2 for β-radiation, to 0.3 - 30 Bq/cm2 for α-radiation and the local dose rate to about 0.03 mSv/h. During the work the accumulated collective doses were listed for breast, hand, head, gonads and foot. In the figure the development with the time of the doses for breast and hand is shown. During restoration work of the cell the accumulated collective whole-body dose amounted to 30 mSv. (orig.)

  1. Radiation therapy for intracranial germ cell tumors

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Shingo; Hayakawa, Kazushige; Tsuchiya, Miwako; Arai, Masahiko; Kazumoto, Tomoko; Niibe, Hideo; Tamura, Masaru

    1988-04-01

    The results of radiation therapy in 31 patients with intracranial germ cell tumors have been analyzed. The five-year survival rates were 70.1 % for germinomas and 38.1 % for teratomas. Three patients with germinoma have since died of spinal seeding. The prophylactic irradiation of the spinal canal has been found effective in protecting spinal seeding, since no relapse of germinoma has been observed in cases that received entire neuraxis iradiation, whereas teratomas and marker (AFP, HCG) positive tumors did not respond favorably to radiation therapy, and the cause of death in these patients has been local failure. Long-term survivors over 3 years after radiation therapy have been determined as having a good quality of life.

  2. Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments

    Science.gov (United States)

    Sun, C.; Zheng, S.; Wei, C. C.; Wu, Y.; Shao, L.; Yang, Y.; Hartwig, K. T.; Maloy, S. A.; Zinkle, S. J.; Allen, T. R.; Wang, H.; Zhang, X.

    2015-01-01

    Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500°C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M23C6 precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

  3. Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents.

    Directory of Open Access Journals (Sweden)

    Fei Xiao

    2014-05-01

    Full Text Available Hepatitis C virus (HCV is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs in state-of-the-art model systems for cell-cell transmission and spread. Using HCV genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host-targeting entry inhibitors (HTEIs was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission plays an important role in dissemination and maintenance of resistant variants in cell culture models. Blocking virus cell-cell transmission prevents emergence of drug resistance in persistent viral infection including resistance to HCV DAAs.

  4. Determinants of resistance to radiation injury in blood granulocytes from normal donors and from patients with myeloproliferative disorders

    International Nuclear Information System (INIS)

    Dose-dependent injury to human blood granulocytes was measured within 2 hr of x irradiation, as changes in net 22Na influx and phagocytosing O2 consumption. Among samples from normal donors and patients with chronic myeloproliferative diseases, samples from 10 to 12 patients with chronic granulocytic leukemia exhibited increased sensitivity to injury by radiation. Selected granulocyte constituents which may contribute to inactivation of oxidant and free-radical products of radiation-activated H2O were also measured. These included glutathione and ascorbate contents; superoxide dismutase, catalase, glutathione proxidase, and glutathione reductase activities; and capacity to take up and reduce dehydroascorbate. Catalase activity was irregularly higher in radiation-sensitive than in radiation-resistant granulocytes (P = < 0.05). Dehydroascorbate uptake and reduction was consistently low in radiation-sensitive cells (P = < 0.001). We propose that cell capacity to maintain ascorbate in reduced form against oxidant and free-radical stress is a part of mechanisms which determine resistance to injury by ionizing radiation in human granulocytes

  5. 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

  6. Molecular exploration of the highly radiation resistant cyanobacterium Arthrospira sp. PCC 8005

    Science.gov (United States)

    Badri, Hanène; Leys, Natalie; Wattiez, Ruddy

    Arthrospira (Spirulina) is a photosynthetic cyanobacterium able to use sunlight to release oxygen from water and remove carbon dioxide and nitrate from water. In addition, it is suited for human consumption (edible). For these traits, the cyanobacterium Arthrospira sp. PCC 8005 was selected by the European Space Agency (ESA) as part of the life support system MELiSSA for recycling oxygen, water, and food during future long-haul space missions. However, during such extended missions, Arthrospira sp. PCC 8005 will be exposed to continuous artificial illumination and harmful cosmic radiation. The aim of this study was to investigate how Arthrospira will react and behave when exposed to such stress environment. The cyanobacterium Arthrospira sp. PCC 8005 was exposed to high gamma rays doses in order to unravel in details the response of this bacterium following such stress. Test results showed that after acute exposure to high doses of 60Co gamma radiation upto 3200 Gy, Arthrospira filaments were still able to restart photosynthesis and proliferate normally. Doses above 3200 Gy, did have a detrimental effect on the cells, and delayed post-irradiation proliferation. The photosystem activity, measured as the PSII quantum yield immediately after irradiation, decreased significantly at radiation doses above 3200 Gy. Likewise through pigment content analysis a significant decrease in phycocyanin was observed following exposure to 3200 Gy. The high tolerance of this bacterium to 60Co gamma rays (i.e. ca. 1000x more resistant than human cells for example) raised our interest to investigate in details the cellular and molecular mechanisms behind this amazing resistance. Optimised DNA, RNA and protein extraction methods and a new microarray chip specific for Arthrospira sp. PCC 8005 were developed to identify the global cellular and molecular response following exposure to 3200 Gy and 5000 Gy A total of 15,29 % and 30,18 % genes were found differentially expressed in RNA

  7. Oxygen radical detoxification enzymes in doxorubicin-sensitive and -resistant P388 murine leukemia cells

    International Nuclear Information System (INIS)

    One of the proposed mechanisms for the cytotoxic effects of anthracycline compounds suggests that the effect is mediated through the formation of intracellular superoxide radicals. It is therefore possible that doxorubicin resistance is associated with increased intracellular enzyme capacity to convert these superoxide radicals to inactive metabolites. We have measured the relative activities of superoxide dismutase, glutathione peroxidase, and catalase in P388 mouse leukemia cells and in a doxorubicin-resistant subline. Since oxygen-reactive metabolites also play a role in mediating the cytotoxicity of ionizing radiation, the radiosensitivity of both cell lines was also studied. No significant differences in superoxide dismutase activity between these cell lines was observed, indicating that they have a similar capacity to convert superoxide anion radicals to hydrogen peroxide. P388 cells that are resistant to doxorubicin have 1.5 times the glutathione content and 1.5 times the activity of glutathione peroxidase measured in drug-sensitive P388 cells. However, incubation with 1-chloro-2,4-dinitrobenzene, which covalently binds glutathione, had no effect on the sensitivity of either cell line to doxorubicin. Measured catalase activity in drug-resistant P388 cells was one-third of the activity measured in doxorubicin-sensitive P388 cells. The activity of this enzyme was much higher than that of glutathione peroxidase in terms of H2O2 deactivation in both cell lines. It is therefore unlikely that doxorubicin-resistant P388 cells have an increased ability to detoxify reactive oxygen metabolites when compared to drug-sensitive cells. Doxorubicin-resistant P388 cells were significantly more sensitive to X-irradiation than were drug-sensitive P388 cells. These observations suggest that the difference in catalase activity in these cell lines may be associated with the observed differences in radiosensitivity

  8. Tumor cell heterogeneity: impact on mechanisms of therapeutic drug resistance

    International Nuclear Information System (INIS)

    Purpose: The aim of these studies was to determine whether chemotherapy-resistant tumor cell sublines derived from a single starting cell population with identical treatment protocols, have the same mechanism of resistance. Methods and Materials: Twelve cyclophosphamide-resistant sublines were derived from KHT-iv murine sarcoma cells by repeated exposures to 2, 4, or 8 μg/ml doses of 4-hydroperoxycyclophosphamide (4-OOHCP). To investigate possible mechanisms of resistance, glutathione (GSH) levels, glutathione S-transferase (GST) activity, and aldehyde dehydrogenase (ALDH) activity were determined. In addition, studies with the GSH depletor buthionine sulfoximine (BSO) and the ALDH inhibitor diethylamino-benzaldehyde (DEAB) were undertaken. Results: Resistant factors to 4-OOHCP, assessed at 10% clonogenic cell survival, ranged from 1.5-7.0 for the various cell lines. Crossresistance to melphalan and adriamycin also were commonly observed. Increased GSH levels, GST activity and ALDH activity were detected in the sublines but not all exhibited the same pattern of biochemical alterations. The response to GSH and ALDH inhibitors also varied among the sublines; the resistance being reversible in some cell lines but not others. Conclusion: The present results indicate that when resistant sublines are derived simultaneously from the same starting cell population, the observed mechanisms of resistance may not be the same in each of the variants. These findings support the hypothesis that preexisting cellular heterogeneity may affect mechanisms of acquired resistance

  9. Kinomic exploration of temozolomide and radiation resistance in Glioblastoma multiforme xenolines

    International Nuclear Information System (INIS)

    Background and purpose: Glioblastoma multiforme (GBM) represents the most common and deadly primary brain malignancy, particularly due to temozolomide (TMZ) and radiation (RT) resistance. To better understand resistance mechanisms, we examined global kinase activity (kinomic profiling) in both treatment sensitive and resistant human GBM patient-derived xenografts (PDX or “xenolines”). Materials and methods: Thirteen orthotopically-implanted xenolines were examined including 8 with known RT sensitivity/resistance, while 5 TMZ resistant xenolines were generated through serial TMZ treatment in vivo. Tumors were harvested, prepared as total protein lysates, and kinomically analyzed on a PamStation®12 high-throughput microarray platform with subsequent upstream kinase prediction and network modeling. Results: Kinomic profiles indicated elevated tyrosine kinase activity associated with the radiation resistance phenotype, including FAK and FGFR1. Furthermore, network modeling showed VEGFR1/2 and c-Raf hubs could be involved. Analysis of acquired TMZ resistance revealed more kinomic variability among TMZ resistant tumors. Two of the five tumors displayed significantly altered kinase activity in the TMZ resistant xenolines and network modeling indicated PKC, JAK1, PI3K, CDK2, and VEGFR as potential mediators of this resistance. Conclusion: GBM xenolines provide a phenotypic model for GBM drug response and resistance that when paired with kinomic profiling identified targetable pathways to inherent (radiation) or acquired (TMZ) resistance

  10. Role of Insulin-Like Growth Factor-1 Signaling Pathway in Cisplatin-Resistant Lung Cancer Cells

    Energy Technology Data Exchange (ETDEWEB)

    Sun Yunguang [Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN (United States); Zheng Siyuan [Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN (United States); Torossian, Artour; Speirs, Christina K.; Schleicher, Stephen; Giacalone, Nicholas J. [Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN (United States); Carbone, David P. [Department of Hematology and Oncology, Vanderbilt University Medical Center, Nashville, TN (United States); Zhao Zhongming, E-mail: zhongming.zhao@vanderbilt.edu [Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN (United States); Lu Bo, E-mail: bo.lu@vanderbilt.edu [Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN (United States)

    2012-03-01

    Purpose: The development of drug-resistant phenotypes has been a major obstacle to cisplatin use in non-small-cell lung cancer. We aimed to identify some of the molecular mechanisms that underlie cisplatin resistance using microarray expression analysis. Methods and Materials: H460 cells were treated with cisplatin. The differences between cisplatin-resistant lung cancer cells and parental H460 cells were studied using Western blot, MTS, and clonogenic assays, in vivo tumor implantation, and microarray analysis. The cisplatin-R cells were treated with human recombinant insulin-like growth factor (IGF) binding protein-3 and siRNA targeting IGF-1 receptor. Results: Cisplatin-R cells illustrated greater expression of the markers CD133 and aldehyde dehydrogenase, more rapid in vivo tumor growth, more resistance to cisplatin- and etoposide-induced apoptosis, and greater survival after treatment with cisplatin or radiation than the parental H460 cells. Also, cisplatin-R demonstrated decreased expression of insulin-like growth factor binding protein-3 and increased activation of IGF-1 receptor signaling compared with parental H460 cells in the presence of IGF-1. Human recombinant IGF binding protein-3 reversed cisplatin resistance in cisplatin-R cells and targeting of IGF-1 receptor using siRNA resulted in sensitization of cisplatin-R-cells to cisplatin and radiation. Conclusions: The IGF-1 signaling pathway contributes to cisplatin-R to cisplatin and radiation. Thus, this pathway represents a potential target for improved lung cancer response to treatment.

  11. Role of Insulin-Like Growth Factor-1 Signaling Pathway in Cisplatin-Resistant Lung Cancer Cells

    International Nuclear Information System (INIS)

    Purpose: The development of drug-resistant phenotypes has been a major obstacle to cisplatin use in non–small-cell lung cancer. We aimed to identify some of the molecular mechanisms that underlie cisplatin resistance using microarray expression analysis. Methods and Materials: H460 cells were treated with cisplatin. The differences between cisplatin-resistant lung cancer cells and parental H460 cells were studied using Western blot, MTS, and clonogenic assays, in vivo tumor implantation, and microarray analysis. The cisplatin-R cells were treated with human recombinant insulin-like growth factor (IGF) binding protein-3 and siRNA targeting IGF-1 receptor. Results: Cisplatin-R cells illustrated greater expression of the markers CD133 and aldehyde dehydrogenase, more rapid in vivo tumor growth, more resistance to cisplatin- and etoposide-induced apoptosis, and greater survival after treatment with cisplatin or radiation than the parental H460 cells. Also, cisplatin-R demonstrated decreased expression of insulin-like growth factor binding protein-3 and increased activation of IGF-1 receptor signaling compared with parental H460 cells in the presence of IGF-1. Human recombinant IGF binding protein-3 reversed cisplatin resistance in cisplatin-R cells and targeting of IGF-1 receptor using siRNA resulted in sensitization of cisplatin-R-cells to cisplatin and radiation. Conclusions: The IGF-1 signaling pathway contributes to cisplatin-R to cisplatin and radiation. Thus, this pathway represents a potential target for improved lung cancer response to treatment.

  12. Radiation response of rodent neural precursor cells

    International Nuclear Information System (INIS)

    Full text: Therapeutic irradiation of the brain can cause cognitive dysfunction that is not treatable or well understood. Several lines of evidence from our laboratory suggest that radiation induced inhibition of neurogenesis in the hippocampus may be involved. To understand the mechanisms underlying these observations, we initiated studies using neural precursor cells isolated from the adult rat hippocampus. Cells were cultured exponentially and analyzed for acute (0-24h) and chronic (3-33 day) changes in apoptosis and oxidative stress following exposure to X-rays. Oxidative stress was measured using a dye sensitive to reactive oxygen species (ROS) and apoptosis was measured using annexin V binding; each endpoint was quantified by fluorescent automated cell sorting (FACS). Following exposure to X-rays, neural precursor cells exhibit a dose-responsive increase in the level of ROS and apoptosis over acute and chronic time frames. ROS and apoptosis were maximal at 12h, increasing 35 and 37% respectively over that of unirradiated controls. ROS and apoptosis peaked again at 24h, increasing 31 and 21% respectively over controls. Chronic levels of ROS and apoptosis were persistently elevated in a dose-dependent manner. ROS showed significant increases (34-180%) over a 3-4 week interval, while increases in apoptosis were less dramatic, rising 45% by week one before dropping to background. Irradiation of rat neural precursor cells was associated with an increase in p53 protein levels, and the activation of G1/S and G2/M checkpoints. These data suggest that the apoptotic and ROS responses may be tied to p53 dependent regulation of cell cycle control and stress activated pathways. We propose that oxidative stress plays a critical role in the radiation response of neural precursor cells, and discuss how this might contribute to the inhibition of neurogenesis and the cognitive impairment observed in the irradiated CNS

  13. Study on production of useful metabolites by development of advanced cell culture techniques using radiation

    International Nuclear Information System (INIS)

    The purpose of this project is improvement of investigation, materialization and evaluation techniques on effectiveness for functional natural compounds throughout development of tissue/cell culture techniques for mass production of useful metabolites using radiation. Research scope includes Development of a technique for radiation tissue and cell culture, Database construction for radiation response in plants and radiation effects, Construction of general-purpose national based techniques of cell culture technique using radiation. Main results are as follow: Isolation and identification of radiation induced basI gene; Determination of stresses sensitivities by transformating basI gene into arabidopsis; Isolation and identification of radiation induced chaperon proteins (PaAhpC and yPrxII) from Pseudomonas and yeast, and structural and functional analysis of the proteins; Determination of oxidative and heat resistance by transformating PaAhpC; Isolation and identification of maysin and its derivatives from centipedgrass; Investigation of enhancement technique for improving maysin and its derivatives production using radiation; Investigation of removing undesirable color in maysin and its derivatives using radiation; Determination of the effect of radiation on physiological functions of centipedgrass extracts; Identification of H2O2 removing enzyme in radiation irradiated plant (Spinach); Determination of the effects of centipedgrass extracts on anti-obesity and anti-cancer activities

  14. Study on production of useful metabolites by development of advanced cell culture techniques using radiation

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Byung Yeoup; Kim, Jinhong; Lee, Seung Sik; Bai, Hyounwoo; An, Byung Chull; Lee, Eun Mi; Lee, Jae Taek; Kim, Mi Ja

    2010-12-15

    The purpose of this project is improvement of investigation, materialization and evaluation techniques on effectiveness for functional natural compounds throughout development of tissue/cell culture techniques for mass production of useful metabolites using radiation. Research scope includes Development of a technique for radiation tissue and cell culture, Database construction for radiation response in plants and radiation effects, Construction of general-purpose national based techniques of cell culture technique using radiation. Main results are as follow: Isolation and identification of radiation induced basI gene; Determination of stresses sensitivities by transformating basI gene into arabidopsis; Isolation and identification of radiation induced chaperon proteins (PaAhpC and yPrxII) from Pseudomonas and yeast, and structural and functional analysis of the proteins; Determination of oxidative and heat resistance by transformating PaAhpC; Isolation and identification of maysin and its derivatives from centipedgrass; Investigation of enhancement technique for improving maysin and its derivatives production using radiation; Investigation of removing undesirable color in maysin and its derivatives using radiation; Determination of the effect of radiation on physiological functions of centipedgrass extracts; Identification of H{sub 2}O{sub 2} removing enzyme in radiation irradiated plant (Spinach); Determination of the effects of centipedgrass extracts on anti-obesity and anti-cancer activities.

  15. Extraction and identification of exosomes from drug-resistant breast cancer cells and their potential role in cell-to-cell drug-resistance transfer

    Institute of Scientific and Technical Information of China (English)

    许金金

    2014-01-01

    Objective To explore whether docetaxel-resistant cells(MCF-7/Doc)and doxorubicin-resistant cells(MCF-7/ADM)can secrete Exosomes and their potential role in cell-cell drug-resistance transfer.Methods Exosomes were extracted from the cell culture supernatants of MCF-7/Doc and MCF-7/ADM cells by fractionation ultracentrifugation,and were identified by transmission

  16. Carcinoembryonic Antigen Expression and Resistance to Radiation and 5-Fluorouracil-Induced Apoptosis and Autophagy.

    Science.gov (United States)

    Eftekhar, Ebrahim; Jaberie, Hajar; Naghibalhossaini, Fakhraddin

    2016-01-01

    Understanding the mechanism of tumor resistance is critical for cancer therapy. In this study, we investigated the effect of carcinoembryonic antigen (CEA) overexpression on UV-and 5-fluorouracil (5-FU)-induced apoptosis and autophagy in colorectal cancer cells. We used histone deacetylase (HDAC) inhibitor, NaB and DNA demethylating agent, 5-azacytidine (5-AZA) to induce CEA expression in HT29/219 and SW742 colorectal cancer cell lines. MTT assay was used to measure IC50 value of the cells exposed to graded concentrations of 5- FU with either 0.1 mM NaB or 1 μM 5-AZA for 72 h . Using CHO- and SW742-CEA transfectants, we also investigated the effect of CEA expression on UV- and 5-FU-induced apoptosis and autophagy. Treatment of HT29/219 cell line with NaB and 5-AZA increased CEA expression by 29% and 31%, respectively. Compared with control cells, the IC50 value for 5-FU of NaB and 5-AZA-treated cells increased by 40% and 57%, respectively. Treatment of SW742 cells with NaB or 5-AZA increased neither CEA expression nor the IC50 value for 5-FU. In comparison to parental cells, CEA expression also significantly protected transfected cells against UV-induced apoptosis. Decreased proportions of autophagy and apoptosis were also observed in 5-FU treated SW742- and CHO-CEA transfectants. We conclude that CEA expression can effectively protect colorectal cancer cells against radiation and drug-induced apoptosis and autophagy. PMID:27478804

  17. Resistance to DNA denaturation in irradiated Chinese hamster V79 fibroblasts is linked to cell shape

    International Nuclear Information System (INIS)

    Exponentially growing Chinese hamster V79-171b lung fibroblasts seeded at high density on plastic (approximately 7 x 10(3) cells/cm2) flatten, elongate, and produce significant amounts of extracellular fibronectin. When lysed in weak alkali/high salt, the rate of DNA denaturation following exposure to ionizing radiation is exponential. Conversely, cells plated at low density (approximately 7 x 10(2) cells/cm2) on plastic are more rounded 24 h later, produce little extracellular fibronectin, and display unusual DNA denaturation kinetics after X-irradiation. DNA in these cells resists denaturation, as though constraints to DNA unwinding have developed. Cell doubling time and distribution of cells in the growth cycle are identical for both high and low density cultures as is cell survival in response to radiation damage. The connection between DNA conformation and cell shape was examined further in low density cultures grown in conditioned medium. Under these conditions, cells at low density were able to elongate, and DNA denaturation of low density cultures was identical to that of high density cultures. Conversely, cytochalasin D, which interferes with actin polymerization causing cells to round up and release fibronectin, allowed development of constraints in high density cultures. These results suggest that DNA conformation is sensitive to changes in cell shape which result when cells are grown in different environments. However, these changes in DNA conformation detected by the DNA unwinding assay do not appear to play a direct role in radiation-induced cell killing

  18. Development of radiation-resistant optical fiber for application to observation and laser spectroscopy under high radiation dose

    International Nuclear Information System (INIS)

    In the Fukushima Daiichi Nuclear Power Station, it is necessary to survey the locations and conditions of fuel debris inside reactor pressure vessels or primary containment vessels under water and radiation environment in preparation for removing fuel debris. An optical fiber is well known for features such as signal transmission, light weight, superior insulation performance, water resistance and electromagnetic noise resistance. These features allow the optical fiber to simplify the instrumentation systems for in-vessel inspection, as long as provide that the optical fiber can be used under high radiation dose environment. The radiation resistance of an optical fiber was improved by increasing the amount of hydroxyl up to 1000 ppm in pure silica fiber. The improved optical fibers were irradiated with γ-ray up to 1 × 106 Gy using a 60Co source. They indicated a large peak around 600 nm and a peak tail from ultraviolet region, but no large absorption in infrared region except a hydroxyl absorption peak of 945 nm. We have confirmed that the optical fiber containing 1000 ppm hydroxyl has enough radiation resistance for radiation-induced transmission losses, and the infrared imaging is effective for observation under high radiation doses. (author)

  19. Radiation hardening and irradiation testing of in-cell electronics for MA23/APM

    International Nuclear Information System (INIS)

    We relate briefly the radiation hardening method used to guarantee a gamma resistance of 10 Mrad for the whole electronic equipment associated with the slave arm of MA23 M servomanipulator which will be set up in cell 404 in Marcoule (APM). We describe the radiation testing of electronic devices and of the various subsystems designed by the D. LETI groups involved in the MA23/APM project

  20. Lumped series resistance of solar cells as a result of distributed sheet resistance

    Science.gov (United States)

    Sokolić, Saša; Križaj, Dejan; Amon, Slavko

    1993-04-01

    An analysis of solar cell distributed sheet resistance is performed by solving the nonlinear Poisson equation for the surface potential. Two different approaches to lumped series resistance are discussed: equivalent series resistance RSeq obtained from the cell's equivalent circuit that satisfies the actual current of the cell (all other parameters in the equivalent circuit except the series resistance are kept constant) and Joule series resistance RSJ obtained from the Joule losses in the emitter of the cell. It is observed that the I( U) characteristic obtained from the equivalent circuit that includes RSJ generally disagrees with the actual I( U) characteristic of the solar cell. An additional series resistance RSadd should be introduced in series with RSJ. Series resistances RSJ, Sadd and RSeq are analyzed numerically in one and two dimensions for different conditions of terminal voltage, illumination and weighted sheet resistance Rshb2, where b is related to the geometry of the analyzed cell. Following the derivations and the results of the numerical analysis it can be concluded that wherever RSJ varies as a function of terminal voltage, RSadd should be taken into consideration.

  1. Genetic study of resistance to inhibitory effects of UV radiation in rice (Oryza sativa)

    International Nuclear Information System (INIS)

    Genetic analysis of resistance to the inhibitory effects of UV radiation on growth of rice (Oryza sativa L.) cultivars was carried out. Some experimental plants were grown in visible radiation supplemented with UV radiation containing a large amount of UV-B and a small amount of UV-C in a phytotron, while others were grown without UV radiation. The degree of resistance to UV radiation was estimated in terms of the degree of reduction caused by supplemental UV radiation in the fresh weight of the aboveground plant parts and the chlorophyll content per unit fresh weight. Fresh weight and chlorophyll content in F2 plants generated by reciprocally crossing cv. Sasanishiki, a cultivar more resistant to UV radiation, and Norin 1, a cultivar less resistant to such radiation exhibited a normal frequency distribution. The heritabilities of these two properties in F2 plants were low under conditions of non-supplemental UV radiation. Under elevated UV radiation, the F2 population shifted to the lower range of fresh weight and chlorophyll content, and the means were close to those of Norin 1. The heritabilities of these two properties were the same in the reciprocal crosses, indicating that maternal inheritance was not involved. Inheritance of chlorophyll content per unit fresh weight was further determined in F3 lines generated by self-fertilizing F2 plants of Sasanishiki and Norin 1. The results showed that the F3 population was segregated into three genotypes, namely, resistant homozygotes, segregated heterozygotes and sensitive homozygotes, with a ratio of 1:65:16. It was thus evident that the resistance to the inhibitory effect of elevated UV radiation in these rice plants was controlled by recessive polygenes. (author)

  2. Overexpression of kinesins mediates docetaxel resistance in breast cancer cells.

    Science.gov (United States)

    De, Sarmishtha; Cipriano, Rocky; Jackson, Mark W; Stark, George R

    2009-10-15

    Resistance to chemotherapy remains a major barrier to the successful treatment of cancer. To understand mechanisms underlying docetaxel resistance in breast cancer, we used an insertional mutagenesis strategy to identify proteins whose overexpression confers resistance. A strong promoter was inserted approximately randomly into the genomes of tumor-derived breast cancer cells, using a novel lentiviral vector. We isolated a docetaxel-resistant clone in which the level of the kinesin KIFC3 was elevated. When KIFC3 or the additional kinesins KIFC1, KIF1A, or KIF5A were overexpressed in the breast cancer cell lines MDA-MB231 and MDA-MB 468, the cells became more resistant to docetaxel. The binding of kinesins to microtubules opposes the stabilizing effect of docetaxel that prevents cytokinesis and leads to apoptosis. Our finding that kinesins can mediate docetaxel resistance might lead to novel therapeutic approaches in which kinesin inhibitors are paired with taxanes. PMID:19789344

  3. Multilevel Cell Storage and Resistance Variability in Resistive Random Access Memory

    Science.gov (United States)

    Pantelis, D. I.; Karakizis, P. N.; Dragatogiannis, D. A.; Charitidis, C. A.

    2016-06-01

    Multilevel per cell (MLC) storage in resistive random access memory (ReRAM) is attractive in achieving high-density and low-cost memory and will be required in future. In this chapter, MLC storage and resistance variability and reliability of multilevel in ReRAM are discussed. Different MLC operation schemes with their physical mechanisms and a comprehensive analysis of resistance variability have been provided. Various factors that can induce variability and their effect on the resistance margin between the multiple resistance levels are assessed. The reliability characteristics and the impact on MLC storage have also been assessed.

  4. 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.

  5. Chemical modification of neoplastic cell transformation by heavy ion radiation

    International Nuclear Information System (INIS)

    Quantitative data on chemical modification of neoplastic cell transformation by heavy-ion radiation was obtained using in-vitro cell transformation technique. The specific aims were 1) to test the potential effects of various chemicals on the expression of cell transformation, and 2) to systematically collect information on the mechanisms of expression and progression of cell transformation by ionizing radiation. Recent experimental studies with DMSO, 5-azacytidine, and dexamethasone suggest that DMSO can effectively suppress the neoplastic cell transformation by high-LET radiation and that some nonmutagenic changes in DNA may be important in modifying the expression, and progression of radiation-induced cell transformation

  6. Investigation of solar cell radiation damage

    International Nuclear Information System (INIS)

    Development of communications satellites has led to the requirement for a greater and longer lived solar cell power source. Accordingly, studies have been undertaken with the aim of determining which solar cell array provides the greatest power at end of life and the amount of degradation. Investigation of the damage done to thin silicon and thin film CdS solar cells is being carried out in two steps. First, irradiations were performed singly with 0.15, 1.0 and 2.0MeV electrons and 0.7, 2.5 and 22MeV proton. Solar cells and their cover materials were irradiated separately in order to locate the sites of the damage. Diffusion length and I.V. characteristics of the cells and transmission properties of the cover materials were measured. All neasurements were made in vacuum immediately after irradiation. In the second part it is intended to study the effect of various combinations of proton, electron and photon irradiation both with and without an electrical load. The results of this part show whether synergism is involved in solar cell damage and the relative importance of each of three radiation sources if synergism is found

  7. RADIATION RESISTANT LED POWER SUPPLY RELEASED UNDER CERN OPEN HARDWARE LICENSE

    CERN Multimedia

    2016-01-01

    As part of the design of a new emergency lighting system for the CERN accelerator complex a new design for a radiation resistant power supply has been produced. The design is available from the Open Hardware Repository.

  8. A gamma-ray-resistant derivative of an ataxia telangiectasia cell line obtained following DNA-mediated gene transfer

    International Nuclear Information System (INIS)

    Genomic DNA from normal human or mouse cells was transfected together with the selectable market gpt into the simian virus 40-transformed ataxia telangiectasia fibroblast line, AT5BIVA. From a series of experiments involving over 400 000 clones selected for the gpt marker, one unambiguously radiation-resistant clone (clone 67) was recovered following selection with repeated cyles of gamma irradiation. The normal level of radiation resistance of clone 67 has been maintained for at least 11 months in the absence of further selection by radiation. The resistant clone contains one copy of the gpt gene. Its DNA synthesis following gamma-radiation is inhibited to an extent intermediate between that of ataxia telangiectasia and normal cells. Three out of four thioguanine-resistant derivatives of clone 67 have either lost or do not express the gpt sequence and show almost the same sensitivity to gamma irradiation as the original AT5BIVA line. This suggests that the radiation resistance of clone 67 may be linked to the gpt sequence and may have arisen as a consequence of the transfection, rather than as the result of an independent mutation to radiation resistance. (author)

  9. Collateral methotrexate resistance in cisplatin-selected murine leukemia cells

    Directory of Open Access Journals (Sweden)

    Bhushan A.

    1999-01-01

    Full Text Available Resistance to anticancer drugs is a major cause of failure of many therapeutic protocols. A variety of mechanisms have been proposed to explain this phenomenon. The exact mechanism depends upon the drug of interest as well as the tumor type treated. While studying a cell line selected for its resistance to cisplatin we noted that the cells expressed a >25,000-fold collateral resistance to methotrexate. Given the magnitude of this resistance we elected to investigate this intriguing collateral resistance. From a series of investigations we have identified an alteration in a membrane protein of the resistant cell as compared to the sensitive cells that could be the primary mechanism of resistance. Our studies reviewed here indicate decreased tyrosine phosphorylation of a protein (molecular mass = 66 in the resistant cells, which results in little or no transfer of methotrexate from the medium into the cell. Since this is a relatively novel function for tyrosine phosphorylation, this information may provide insight into possible pharmacological approaches to modify therapeutic regimens by analyzing the status of this protein in tumor samples for a better survival of the cancer patients.

  10. Carboplatin treatment of antiestrogen-resistant breast cancer cells

    DEFF Research Database (Denmark)

    Larsen, Mathilde S; Yde, Christina Westmose; Christensen, Ib J;

    2012-01-01

    sensitivity to carboplatin, as it was previously shown with cisplatin, and whether low Bcl-2 expression levels have a potential value as marker for increased carboplatin sensitivity. Breast cancer cells resistant to the pure antiestrogen fulvestrant, and two out of four cell lines resistant to the...... antiestrogen tamoxifen, were more sensitive to carboplatin treatment compared to the parental MCF-7 cell line. This indicates that carboplatin may be an advantageous treatment in antiestrogen‑resistant breast cancer; however, a marker for increased sensitivity would be needed. Low Bcl-2 expression was...... combination with Bcl-xL and Bax, could explain the observed responses to carboplatin in all tamoxifen‑resistant cell lines, indicating that more markers are needed to predict the response to carboplatin in tamoxifen‑resistant breast cancer....

  11. Isolation and characterization of human cells resistant to retrovirus infection

    Directory of Open Access Journals (Sweden)

    Somia Nikunj V

    2007-07-01

    Full Text Available Abstract Background Identification of host cell proteins required for HIV-1 infection will add to our knowledge of the life cycle of HIV-1 and in the development of therapeutics to combat viral infection. We and other investigators have mutagenized rodent cells and isolated mutant cell lines resistant to retrovirus infection. Since there are differences in the efficiency of single round infection with VSVG pseudotyped HIV-1 on cells of different species, we conducted a genetic screen to isolate human cells resistant to HIV-1 infection. We chemically mutagenized human HeLa cells and validated our ability to isolate mutants at test diploid loci. We then executed a screen to isolate HeLa cell mutants resistant to infection by an HIV-1 vector coding for a toxic gene product. Results We isolated two mutant cell lines that exhibit up to 10-fold resistance to infection by HIV-1 vectors. We have verified that the cells are resistant to infection and not defective in gene expression. We have confirmed that the resistance phenotype is not due to an entry defect. Fusion experiments between mutant and wild-type cells have established that the mutations conferring resistance in the two clones are recessive. We have also determined the nature of the block in the two mutants. One clone exhibits a block at or before reverse transcription of viral RNA and the second clone has a retarded kinetic of viral DNA synthesis and a block at nuclear import of the preintegration complex. Conclusion Human cell mutants can be isolated that are resistant to infection by HIV-1. The mutants are genetically recessive and identify two points where host cell factors can be targeted to block HIV-1 infection.

  12. Multidrug resistance of tumor cells: some new trends in research

    OpenAIRE

    Stavrovskaya, A. A.; G. P. Guens

    2014-01-01

    Multidrug resistance (MDR) of tumor cells is the resistance to a broad spectrum of structurally unrelated cytotoxic drugs with different mechanisms of action. One of the main causes of MDR phenotype is the activity of ATP-binding cassette transporters (ABC transporters). ABC transporters efflux toxic compounds from the cells. All living cells contain ABC transporters. This review is dedicated to the studies of three-dimensional structure of ABC transporters, to the data concerning MDR evoluti...

  13. The effect of radiation intensity on diode characteristics of silicon solar cells

    International Nuclear Information System (INIS)

    In order to explore electro-physical properties of silicon solar cells, diode characteristics and ohmic properties of Al - Ni / (n+) - Si contact has been studied. Diode characteristics have been studied on a wide temperature range and on various radiation intensity, so this gives us the ability to observe the effect of the radiation and the temperature on electro-physical properties of under study solar cells. Volt-Ampere characteristics of the ohmic contacts of the silicon solar cells have been presented. As well as contact resistance and mechanism of current transmission has been identified.

  14. Effect of various polymeric binders on the radiation resistance of glass fiber HEPA filter media

    International Nuclear Information System (INIS)

    Glass fiber HEPA filter media bonded with various polymeric materials were exposed to several levels of radiation dosage from an electron beam source. The effects on water repellency, tensile strength, DOP filtration efficiency and organic content were noted. All media suffered degradation at the highest levels of radiation dosage (7 x 108 rads). However, at intermediate levels, radiation resistance was affected by the type of binder. Greatest resistance to radiation was exhibited by media bonded with a phenylated polysiloxane resin. Cross-linking polymers such as polystyrene and SBR displayed improvement in some properties, such as in water repellency and tensile strength, at low levels of radiation exposure (less than 2 x 108 rads), however degraded at higher levels of exposure. Filtration properties such as DOP efficiency and resistance to air flow did not appear to be greatly affected by radiolysis. (U.S.)

  15. Study on production of useful metabolites by development of advanced cell culture techniques using radiation

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Byung Yeoup; Lee, Seung Sik; Bai, Hyounwoo; Singh, Sudhir; Lee, Eun Mi; Hong, Sung Hyun; Park, Chul Hong; Srilatha, B.; Kim, Mi Ja; Lee, Ohchul

    2012-01-15

    The purpose of this project is improvement of investigation, materialization and evaluation techniques on effectiveness for functional natural compounds throughout development of tissue/cell culture techniques for mass production of useful metabolites using radiation. Research scope includes Development of a technique for radiation tissue and cell culture, Database construction for radiation response in plants and radiation effects, Construction of general-purpose national based techniques of cell culture technique using radiation. Main results are as follow: Development of a technique for radiation tissue and cell culture for Erigeron breviscapus (Vant.) Hand. Mazz.; Identification and functional analysis of AtTDX (chaperone and peroxidase activities); Functional analysis of radiation(gamma ray, electron beam, and proton beam) induced chaperon protein activities (AtTDX); Determine the action mechanism of yPrx2; Development of transgenic plant with bas I gene from Arabidopsis; Development of transgenic plant with EoP gene from centipedegrass; Identification of radiation induced multi functional compounds from Aloe; Determination of the effects of radiation on removing undesirable color and physiological activities (Schizandra chinensis baillon, centipedegrass); Determine the action mechanism of transgenic plant with 2-Cys Prx for heat stress resistance; Determination of the effects of centipedegrass extracts on anti-cancer activities; Functional analysis of centipedegrass extracts (anti-virus effects)

  16. Study on production of useful metabolites by development of advanced cell culture techniques using radiation

    International Nuclear Information System (INIS)

    The purpose of this project is improvement of investigation, materialization and evaluation techniques on effectiveness for functional natural compounds throughout development of tissue/cell culture techniques for mass production of useful metabolites using radiation. Research scope includes Development of a technique for radiation tissue and cell culture, Database construction for radiation response in plants and radiation effects, Construction of general-purpose national based techniques of cell culture technique using radiation. Main results are as follow: Development of a technique for radiation tissue and cell culture for Erigeron breviscapus (Vant.) Hand. Mazz.; Identification and functional analysis of AtTDX (chaperone and peroxidase activities); Functional analysis of radiation(gamma ray, electron beam, and proton beam) induced chaperon protein activities (AtTDX); Determine the action mechanism of yPrx2; Development of transgenic plant with bas I gene from Arabidopsis; Development of transgenic plant with EoP gene from centipedegrass; Identification of radiation induced multi functional compounds from Aloe; Determination of the effects of radiation on removing undesirable color and physiological activities (Schizandra chinensis baillon, centipedegrass); Determine the action mechanism of transgenic plant with 2-Cys Prx for heat stress resistance; Determination of the effects of centipedegrass extracts on anti-cancer activities; Functional analysis of centipedegrass extracts (anti-virus effects)

  17. Radiation Resistance of Spores of Clostridium Botulinum Type E

    International Nuclear Information System (INIS)

    The resistance of spores of Clostridium botulinum Type E to radiation with 60Co was determined in 1:2 haddock homogenate and in neutral phosphate buffer. Inoculated samples were irradiated at 0.1 Mrad internal doses at 35°F (1.7°C). The number of survivors at each dose was determined in a medium consisting of 5% peptone, 16% gelatin and 0,1% sodium thioglycollate, using a replicate deep-tube recovery method and incubation at 68°F (20°C) and 46°F (7.8°C). Survivor curves were constructed by plotting log per cent survivors against dose, The viable counts of unirradiated spores at 68°F and 46°F were used to calculate the respective per cent survivors. Survivor curves for spores of the Beluga, 8E, Alaska and Minneapolis strains in both substrates and at both temperatures were characterized by a pronounced shoulder or lag during the first log cycle of reduction, followed by exponential destruction. Lag values, defined as the dose in Mrad for a survivor curve to traverse the first log cyclevof reduction, were larger with haddock than with buffer,and larger with incubation at 68°F than at 46°F. Lagvalues of spores in haddock at 68°F ranged from 0.29 to 0.43 Mrad. At 46°F, the lag values equalled approximately 0.25 Mrad. In buffer at 68°F, the lag values ranged from 0.21 to 0.30 Mrad versus 0.13 to 0.20 Mrad at 46°F. D-values, defined as the dose for 90°jo reduction from the exponential portion of a survivor curve, equalled 0. 22 Mrad in haddock and 0. 08 to 0.11 Mrad in buffer at 68°F. D-values of 0. 08 to 0.11 Mrad were obtained in both haddock and buffer at 46°F. From partial spoilage data at 85°F (29.4°C), spores of the 8E and Minneapolis strains showed D-values equal to 0.25 Mrad. More than a twofold reduction in resistance was observed with incubation at 46°F. D-values for 106 inactivation from extrapolation of the survivor curves compared closely to those calculated from partial spoilage results. The survivor curve for spores of the Beluga strain

  18. Troglitazone reverses the multiple drug resistance phenotype in cancer cells

    Directory of Open Access Journals (Sweden)

    Gerald F Davies

    2009-03-01

    Full Text Available Gerald F Davies1, Bernhard HJ Juurlink2, Troy AA Harkness11Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, Saskatoon, Canada; 2College of Medicine, Alfaisal University, Riyadh, Kingdom of Saudi ArabiaAbstract: A major problem in treating cancer is the development of drug resistance. We previously demonstrated doxorubicin (DOX resistance in K562 human leukemia cells that was associated with upregulation of glyoxalase 1 (GLO-1 and histone H3 expression. The thiazolidinedione troglitazone (TRG downregulated GLO-1 expression and further upregulated histone H3 expression and post-translational modifications in these cells, leading to a regained sensitivity to DOX. Given the pleiotropic effects of epigenetic changes in cancer development, we hypothesized that TRG may downregulate the multiple drug resistance (MDR phenotype in a variety of cancer cells. To test this, MCF7 human breast cancer cells and K562 cells were cultured in the presence of low-dose DOX to establish DOX-resistant cell lines (K562/DOX and MCF7/DOX. The MDR phenotype was confirmed by Western blot analysis of the 170 kDa P-glycoprotein (Pgp drug efflux pump multiple drug resistance protein 1 (MDR-1, and the breast cancer resistance protein (BCRP. TRG markedly decreased expression of both MDR-1 and BCRP in these cells, resulting in sensitivity to DOX. Silencing of MDR-1 expression also sensitized MCF7/DOX cells to DOX. Use of the specific and irreversible peroxisome proliferator-activated receptor gamma (PPARγ inhibitor GW9662 in the nanomolar range not only demonstrated that the action of TRG on MCF/DOX was PPARγ-independent, but indicated that PPARγ may play a role in the MDR phenotype, which is antagonized by TRG. We conclude that TRG is potentially a useful adjunct therapy in chemoresistant cancers. Keywords: chemotherapy, doxorubicin, breast cancer resistance protein-1, multiple drug resistance, multiple drug resistance protein 1

  19. Overcome Cancer Cell Drug Resistance Using Natural Products

    Directory of Open Access Journals (Sweden)

    Pu Wang

    2015-01-01

    Full Text Available Chemotherapy is one of the major treatment methods for cancer. However, failure in chemotherapy is not uncommon, mainly due to dose-limiting toxicity associated with drug resistance. Management of drug resistance is important towards successful chemotherapy. There are many reports in the Chinese literature that natural products can overcome cancer cell drug resistance, which deserve sharing with scientific and industrial communities. We summarized the reports into four categories: (1 in vitro studies using cell line models; (2 serum pharmacology; (3 in vivo studies using animal models; and (4 clinical studies. Fourteen single compounds were reported to have antidrug resistance activity for the first time. In vitro, compounds were able to overcome drug resistance at nontoxic or subtoxic concentrations, in a dose-dependent manner, by inhibiting drug transporters, cell detoxification capacity, or cell apoptosis sensitivity. Studies in vivo showed that single compounds, herbal extract, and formulas had potent antidrug resistance activities. Importantly, many single compounds, herbal extracts, and formulas have been used clinically to treat various diseases including cancer. The review provides comprehensive data on use of natural compounds to overcome cancer cell drug resistance in China, which may facilitate the therapeutic development of natural products for clinical management of cancer drug resistance.

  20. Cell/Tissue Culture Radiation Exposure Facility Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a Cell/Tissue Culture Radiation Exposure Facility (CTC-REF) to enable radiobiologists to investigate the real-time radiation effects on...

  1. Estimation of thermal shock resistance of fine porous alumina by infrared radiation heating method

    OpenAIRE

    Iwamoto, Yuji; Honda, Sawao; Ogihara, Yuki; Kishi, Tsunego; イワモト, ユウジ; ホンダ, サワオ; 岩本, 雄二; 本多, 沢雄

    2009-01-01

    The thermal shock resistance of α-alumina porous capillary, the support material for hydrogen-permselective microporous ceramic membrane was studied. To study the effect of porosity on the thermal shock resistance systematically, porous alumina with different porosities was fabricated, and the thermal shock resistance of the fabricated samples as well as the porous capillary was estimated by the infrared radiation heating method. The mechanical and thermal properties concerned to the thermal ...

  2. Radiation responses of stem cells: targeted and non-targeted effects

    International Nuclear Information System (INIS)

    Stem cells are fundamental to the development of any tissue or organism via their ability to self-renew, which is aided by their unlimited proliferative capacity and their ability to produce fully differentiated offspring, often from multiple lineages. Stems cells are long lived and have the potential to accumulate mutations, including in response to radiation exposure. It is thought that stem cells have the potential to be induced into a cancer stem cell phenotype and that these may play an important role in resistance to radiotherapy. For radiation-induced carcinogenesis, the role of targeted and non-targeted effects is unclear with tissue or origin being important. Studies of genomic instability and bystander responses have shown consistent effects in haematopoietic models. Several models of radiation have predicted that stem cells play an important role in tumour initiation and that bystander responses could play a role in proliferation and self-renewal. (authors)

  3. Radiation-hard, high efficiency InP solar cell and panel development

    International Nuclear Information System (INIS)

    Indium phosphide solar cells with efficiencies over 19% (Air mass zero, 25 degrees C) and area of 4 cm2 have been made and incorporated into prototype panels. The panels will be tested in space to confirm the high radiation resistance expected from InP solar cells, which makes the material attractive for space use, particularly in high-radiation orbits. Laboratory testing indicated an end-of-life efficiency of 15.5% after 1015 1 MeV electrons, and 12% after 1016. These cells are made by metalorganic chemical vapor deposition, and have a shallow homojunction structure. The manufacturing process is amendable to scale-up to larger volumes; more than 200 cells were produced in the laboratory operation. Cell performance, radiation degradation, annealing behavior, and results of deep level transient spectroscopy studies are presented in this paper

  4. Radiolabeled blood cells: radiation dosimetry and significance

    International Nuclear Information System (INIS)

    Over the past few years blood cells labeled with In-111 have become increasingly useful in clinical diagnosis and biomedical research. Indium-111 by the virtue of its physical characteristics and ability to bind to cell cytoplasmic components, provides an excellent cell tracer and thereby, allows investigators to monitor in vivo cell distribution by external imaging and help determine a course of regimen in treating life threatening diseases. Due to natural phenomena such as margination, blood pool, and reticuloendothelial cell activity, in the normal state, depending upon the cell type and the quality of cell preparations, 30%-50% of the administered radioactivity is immediately distributed in the liver, spleen and bone marrow. Over a period of time the radioactivity in these organs slightly increases and decays with a physical half-life of In-111. The resulting radiation dose to these organs ranges between 1-25 rads/mCi In-111 administered. The authors have developed a new In-111 labeling technique which preserves platelet ultrastructure and shown that human lymphocytes labeled with In-111 in mixed leukocytes preparations a) are only 0.003% of the total -body lymphocytes population and b) are killed. The consequence if any may be considered insignificant, particularly because 5.6% metaphases from normal men and 6.5% metaphases from normal women in the US have at least one chromosome aberration. Calculations have shown that the risk of fatal hematological malignancy, over a 30 year period, in recipients of 100 million lymphocytes labeled with 100 μCi In-111 is 1/million patients studied. This risk is less than 0.025% of the 1981 spontaneous cancer patient rate in the country. 32 references, 10 tables

  5. Development of a radiation measurement system based on radiation and heat resistant materials

    International Nuclear Information System (INIS)

    This paper explains the following themes that Hokkaido University is currently promoting as a core agent, (1) development of diamond semiconductor device for nuclear reactors with the aim of severe accident countermeasure, and (2) development of an underlying technology for portable energy differentiation and position detective α-ray measuring device. The theme (1) is the attempt of developing diamond semiconductor device for use in the equipment used in a reactor containment vessel, which faces increasing demands for very tough resistance against radiation and high-temperatures after the Fukushima Daiichi Nuclear Power Station accident. The development of diamond FET that works stably at 500degC was successfully made, and a diamond detector for γ-rays has come to satisfy the performance demands such as 300degC or above, 5 MGy, and dynamic range of 7-digits. The theme (2) is the development of an underlying technology for scintillator-based portable energy differentiation and position detective α-ray measurement device for use in the in-situ measurement of α-ray emitting nuclei originated from nuclear fuel such as 238Pu, under high γ-ray and β-ray background, which is required in environmental measurement and decommissioning work. The development of the device capable of discriminating Pu of 0.37 Bq within 5 min under the environment of Pu: Rn progeny nuclei abundance ratio = 1: 100 was successfully made. Both projects are based on the development of the materials that can withstand both harsh radiation and high-temperature environments. (author)

  6. Breast cancer cells with acquired antiestrogen resistance are sensitized to cisplatin-induced cell death

    DEFF Research Database (Denmark)

    Yde, Christina Westmose; Gyrd-Hansen, Mads; Lykkesfeldt, Anne E; Issinger, Olaf-Georg; Stenvang, Jan

    2007-01-01

    future breast cancer treatment. In this study, we have investigated the effect of the chemotherapeutic compound cisplatin using a panel of antiestrogen-resistant breast cancer cell lines established from the human breast cancer cell line MCF-7. We show that the antiestrogen-resistant cells are...... parental MCF-7 cells. Our data show that Bcl-2 can protect antiestrogen-resistant breast cancer cells from cisplatin-induced cell death, indicating that the reduced expression of Bcl-2 in the antiestrogen-resistant cells plays a role in sensitizing the cells to cisplatin treatment.......Antiestrogens are currently used for treating breast cancer patients who have estrogen receptor-positive tumors. However, patients with advanced disease will eventually develop resistance to the drugs. Therefore, compounds effective on antiestrogen-resistant tumors will be of great importance for...

  7. Characterisation and Manipulation of Docetaxel Resistant Prostate Cancer Cell Lines

    LENUS (Irish Health Repository)

    O'Neill, Amanda J

    2011-10-07

    Abstract Background There is no effective treatment strategy for advanced castration-resistant prostate cancer. Although Docetaxel (Taxotere®) represents the most active chemotherapeutic agent it only gives a modest survival advantage with most patients eventually progressing because of inherent or acquired drug resistance. The aims of this study were to further investigate the mechanisms of resistance to Docetaxel. Three Docetaxel resistant sub-lines were generated and confirmed to be resistant to the apoptotic and anti-proliferative effects of increasing concentrations of Docetaxel. Results The resistant DU-145 R and 22RV1 R had expression of P-glycoprotein and its inhibition with Elacridar partially and totally reversed the resistant phenotype in the two cell lines respectively, which was not seen in the PC-3 resistant sublines. Resistance was also not mediated in the PC-3 cells by cellular senescence or autophagy but multiple changes in pro- and anti-apoptotic genes and proteins were demonstrated. Even though there were lower basal levels of NF-κB activity in the PC-3 D12 cells compared to the Parental PC-3, docetaxel induced higher NF-κB activity and IκB phosphorylation at 3 and 6 hours with only minor changes in the DU-145 cells. Inhibition of NF-κB with the BAY 11-7082 inhibitor reversed the resistance to Docetaxel. Conclusion This study confirms that multiple mechanisms contribute to Docetaxel resistance and the central transcription factor NF-κB plays an immensely important role in determining docetaxel-resistance which may represent an appropriate therapeutic target.

  8. DNA Methylation and Apoptosis Resistance in Cancer Cells

    OpenAIRE

    Pierre-François Cartron; François Marie Vallette; Eric Hervouet; Mathilde Cheray

    2013-01-01

    Apoptosis is a cell death programme primordial to cellular homeostasis efficiency. This normal cell suicide program is the result of the activation of a cascade of events in response to death stimuli. Apoptosis occurs in normal cells to maintain a balance between cell proliferation and cell death. A deregulation of this balance due to modifications in the apoptosic pathway leads to different human diseases including cancers. Apoptosis resistance is one of the most important hallmarks of cance...

  9. Hydrodynamic resistance of confined cells in rectangular microchannels

    Science.gov (United States)

    Khan, Zeina S.; Vanapalli, Siva A.

    2011-03-01

    Several microfluidic approaches have been developed to screen suspended cells mechanically in microchannels by exploiting characteristics that are linked to their individual mechanical properties. Typically changes in cell shape due to shear-induced deformation and transit times are reported; while these measurements are qualitative compared to more precise techniques such as atomic force microscopy and micropipette aspiration their advantage lies in throughput, with the ability to screen hundreds to thousands of cells in a minute. We study the potential of a microfluidic cell squeezer to characterize the hydrodynamic resistance of LNCaP prostate cancer cells by measuring dynamical pressure-drop variations along a micrometer-sized channel. The hydrodynamic resistance of the cell introduces an excess pressure drop in the narrow channel which depends on the mechanical stiffness of the cell. We additionally visualize the cell size and assess the influence of cell size on the hydrodynamic resistance of each cell, demonstrating the capability of the microfluidic cell squeezer to yield the hydrodynamic resistance as a mechanical fingerprint of cells.

  10. Metallic Photonic Bandgap Resonant Antennas with High Directivity and High Radiation Resistance

    Institute of Scientific and Technical Information of China (English)

    林青春; 符建; 何赛灵; 章坚武

    2002-01-01

    A metallic photonic bandgap (MPBG) resonant antenna is introduced, which has novel characteristics (such as high directivity and high radiation resistance for a certain range of frequencies) as compared to conventional MPBG antennas. The linear MPBG resonant antenna is formed by infinitely long metallic rods in vacuum. The numerical results for the radiation pattern and the radiation resistance are presented. By adjusting the struct ure of the MPBG resonant antenna and its working frequency, an optimal structure is achieved. The physical reasons for the novel characteristics of the MPBG resonant antenna are also explained.

  11. Role of lymphocyte-specific protein tyrosine kinase (LCK) in the expansion of glioma-initiating cells by fractionated radiation

    International Nuclear Information System (INIS)

    Research highlights: → Activation of Lymphocyte-specific protein tyrosine kinase (LCK) is involved in the fractionated radiation-induced expansion of glioma stem-like cells. → Inhibition of LCK prevents acquisition of fractionated radiation-induced resistance to chemotherapeutic treatment. → LCK activity is critical for the maintenance of self-renewal in glioma stem-like cells. -- Abstract: Brain cancers frequently recur or progress as focal masses after treatment with ionizing radiation. Radiation used to target gliomas may expand the cancer stem cell population and enhance the aggressiveness of tumors; however, the mechanisms underlying the expansion of cancer stem cell population after radiation have remained unclear. In this study, we show that LCK (lymphocyte-specific protein tyrosine kinase) is involved in the fractionated radiation-induced expansion of the glioma-initiating cell population and acquisition of resistance to anticancer treatments. Fractionated radiation caused a selective increase in the activity of LCK, a Src family non-receptor tyrosine kinase. The activities of other Src family kinases Src, Fyn, and Lyn were not significantly increased. Moreover, knockdown of LCK expression with a specific small interfering RNA (siRNA) effectively blocked fractionated radiation-induced expansion of the CD133+ cell population. siRNA targeting of LCK also suppressed fractionated radiation-induced expression of the glioma stem cell marker proteins CD133, Nestin, and Musashi. Expression of the known self-renewal-related proteins Notch2 and Sox2 in glioma cells treated with fractionated radiation was also downregulated by LCK inhibition. Moreover, siRNA-mediated knockdown of LCK effectively restored the sensitivity of glioma cells to cisplatin and etoposide. These results indicate that the non-receptor tyrosine kinase LCK is critically involved in fractionated radiation-induced expansion of the glioma-initiating cell population and decreased cellular

  12. Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents

    DEFF Research Database (Denmark)

    Xiao, Fei; Fofana, Isabel; Heydmann, Laura;

    2014-01-01

    -targeting entry inhibitors (HTEIs) was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission......Hepatitis C virus (HCV) is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In...... contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs) in state-of-the-art model systems for cell-cell transmission and spread. Using HCV...

  13. Genetic resistance to rhabdovirus infection in teleost fish is paralleled to the derived cell resistance status.

    Science.gov (United States)

    Verrier, Eloi R; Langevin, Christelle; Tohry, Corinne; Houel, Armel; Ducrocq, Vincent; Benmansour, Abdenour; Quillet, Edwige; Boudinot, Pierre

    2012-01-01

    Genetic factors of resistance and predisposition to viral diseases explain a significant part of the clinical variability observed within host populations. Predisposition to viral diseases has been associated to MHC haplotypes and T cell immunity, but a growing repertoire of innate/intrinsic factors are implicated in the genetic determinism of the host susceptibility to viruses. In a long-term study of the genetics of host resistance to fish rhabdoviruses, we produced a collection of double-haploid rainbow trout clones showing a wide range of susceptibility to Viral Hemorrhagic Septicemia Virus (VHSV) waterborne infection. The susceptibility of fibroblastic cell lines derived from these clonal fish was fully consistent with the susceptibility of the parental fish clones. The mechanisms determining the host resistance therefore did not associate with specific host immunity, but rather with innate or intrinsic factors. One cell line was resistant to rhabdovirus infection due to the combination of an early interferon IFN induction--that was not observed in the susceptible cells--and of yet unknown factors that hamper the first steps of the viral cycle. The implication of IFN was well consistent with the wide range of resistance of this genetic background to VSHV and IHNV, to the birnavirus IPNV and the orthomyxovirus ISAV. Another cell line was even more refractory to the VHSV infection through different antiviral mechanisms. This collection of clonal fish and isogenic cell lines provides an interesting model to analyze the relative contribution of antiviral pathways to the resistance to different viruses. PMID:22514610

  14. Comments on the Japanese study of the radiation resistance of the bioburden of medical devices

    International Nuclear Information System (INIS)

    The findings obtained in an extensive study of the radiation resistance electrons, even with a broad energy sa number of medical devices has been carried out by Takehisa et al. and reported in this number of this Journal. The following paper reviews the expected behaviour of the reported populations under the conditions specified in ISO Standard 11137 Method 1, which is widely used in the determination of the radiation sterilization dose required for sterilization of medical devices. The populations reported for 'dry' devices contain a higher proportion of more radiation resistant microbes than that found in the standard distribution of resistance (SDR) that is used for setting the sterilization dose in Method 1. A possible alternative dose setting method for more resistant microbial populations is introduced and discussed

  15. Comments on the Japanese study of the radiation resistance of the bioburden of medical devices

    Energy Technology Data Exchange (ETDEWEB)

    Whitby, James L

    1998-06-01

    The findings obtained in an extensive study of the radiation resistance electrons, even with a broad energy sa number of medical devices has been carried out by Takehisa et al. and reported in this number of this Journal. The following paper reviews the expected behaviour of the reported populations under the conditions specified in ISO Standard 11137 Method 1, which is widely used in the determination of the radiation sterilization dose required for sterilization of medical devices. The populations reported for 'dry' devices contain a higher proportion of more radiation resistant microbes than that found in the standard distribution of resistance (SDR) that is used for setting the sterilization dose in Method 1. A possible alternative dose setting method for more resistant microbial populations is introduced and discussed.

  16. Comments on the Japanese study of the radiation resistance of the bioburden of medical devices

    Science.gov (United States)

    Whitby, James L.

    1998-06-01

    The findings obtained in an extensive study of the radiation resistance of microbes forming the bioburden of a number of medical devices has been carried out by Takehisa et al. and reported in this number of this Journal. The following paper reviews the expected behaviour of the reported populations under the conditions specified in ISO Standard 11137 Method 1, which is widely used in the determination of the radiation sterilization dose required for sterilization of medical devices. The populations reported for "dry" devices contain a higher proportion of more radiation resistant microbes than that found in the standard distribution of resistance (SDR) that is used for setting the sterilization dose in Method 1. A possible alternative dose setting method for more resistant microbial populations is introduced and discussed.

  17. Radiation damage resistance and interface stability of copper–graphene nanolayered composite

    International Nuclear Information System (INIS)

    The radiation damage resistance and interface stability of copper–graphene nanolayered composite are studied by atomistic simulations. Results show that the number of surviving point defects in bulk region is always less than that of pure copper at 100 K, when the range of initial distance d between a primary knock-on atom (PKA) with 3 keV and copper–graphene interface is less than 4 nm. The above phenomenon also occurs at 300, 500, and 700 K when d is ∼15.4 Å, thereby implying that the composite resulting from copper–graphene interfaces exhibits excellent ability to resist radiation damage. A higher PKA energy corresponds to worse radiation damage of graphene in the composite. The damage may impair interface stability and eventually weaken the radiation damage resistance of the composite

  18. Acquired-resistance of bevacizumab treatment for radiation brain necrosis: a case report

    Science.gov (United States)

    Sun, Dayong; Bian, Jianliang; Chang, Joe Y.; Yuan, Zhiyong; Wang, Ping

    2016-01-01

    The case study reported on acquired bevacizumab resistance in one patient receiving re-treatment with bevacizumab following radiation brain necrosis progression after bevacizumab was discontinued. This case offers novel and additional insight for bevacizumab treatment. Low-dose bevacizumab is effective for radiation brain necrosis, and radiation brain necrosis may progress after bevacizumab discontinuation, whereas too many cycles of bevacizumab treatment may induce drug-resistance and re-treatment failure following the progression. Therefore, more rational administration for radiation brain necrosis with bevacizumab may include three aspects: short-course treatment, timely discontinuation upon obtaining satisfactory effects (to prevent long-term medication associated resistance) and re-treatment after brain necrosis progression. PMID:26933810

  19. Present status and prospects of R&D of radiation-resistant semiconductor devices at JAEA

    Science.gov (United States)

    Itoh, H.

    2013-05-01

    Research and development of radiation resistant semiconductor devices have been performed at Japan Atomic Energy Agency (JAEA) for their application to electronic system used in harsh environments like space, accelerator and nuclear facilities. Such devices are also indispensable for robots and equipment necessary for decommissioning of the damaged reactors at Fukushima Daiichi Nuclear Power Plants. For this purpose, we have fabricated transistors based on a wide band-gap semiconductor SiC and examined their radiation degradation. As a result, SiC-based transistors exhibited no significant degradation up to 1MGy, indicating their excellent radiation resistance. Recent our R&Ds of radiation resistant devices based on SiC are summarized and reviewed.

  20. Isolated cell behavior drives the evolution of antibiotic resistance

    OpenAIRE

    Artemova, Tatiana; Gerardin, Ylaine; Dudley, Carmel; Vega, Nicole M.; Gore, Jeff

    2015-01-01

    Bacterial antibiotic resistance is typically quantified by the minimum inhibitory concentration (MIC), which is defined as the minimal concentration of antibiotic that inhibits bacterial growth starting from a standard cell density. However, when antibiotic resistance is mediated by degradation, the collective inactivation of antibiotic by the bacterial population can cause the measured MIC to depend strongly on the initial cell density. In cases where this inoculum effect is strong, the rela...

  1. Cell biological mechanisms of multidrug resistance in tumors.

    OpenAIRE

    Simon, S. M.; Schindler, M

    1994-01-01

    Multidrug resistance (MDR) is a generic term for the variety of strategies tumor cells use to evade the cytotoxic effects of anticancer drugs. MDR is characterized by a decreased sensitivity of tumor cells not only to the drug employed for chemotherapy but also to a broad spectrum of drugs with neither obvious structural homology nor common targets. This pleiotropic resistance is one of the major obstacles to the successful treatment of tumors. MDR may result from structural or functional cha...

  2. Is resistance futile? Changing external resistance does not improve microbial fuel cell performance.

    Science.gov (United States)

    Lyon, Delina Y; Buret, Francois; Vogel, Timothy M; Monier, Jean-Michel

    2010-04-01

    Microbial fuel cells (MFCs) show promise as an alternative to conventional batteries for point source electricity generation. A better understanding of the relationship between the microbiological and electrical aspects of fuels cells is needed prior to successful MFC application. Here, we observed the effects of external resistance on power production and the anodic biofilm community structure. Large differences in the external resistance affected both power production and microbial community structure. After the establishment of the anodic microbial community, change in external resistance (from low to high and vice versa) changed the anodic microbial community structure, but the resulting community did not resemble the communities established at that same external resistance. Different microbial community structures, established under different external resistances, resulted in similar power production, demonstrating the flexibility of the MFC system. PMID:19783225

  3. The concept of radiation-enhanced stem cell differentiation

    International Nuclear Information System (INIS)

    Efficient stem cell differentiation is considered to be the holy grail of regenerative medicine. Pursuing the most productive method of directed differentiation has been the subject of numerous studies, resulting in the development of many effective protocols. However, the necessity for further improvement in differentiation efficiency remains. This review contains a description of molecular processes underlying the response of stem cells to ionizing radiation, indicating its potential application in differentiation procedures. In the first part, the radiation-induced damage response in various types of stem cells is described. Second, the role of the p53 protein in embryonic and adult stem cells is highlighted. Last, the hypothesis on the mitochondrial involvement in stem cell development including its response to ionizing radiation is presented. In summary, despite the many threats of ionizing radiation concerning genomic instability, subjecting cells to the appropriate dosage of ionizing radiation may become a useful method for enhancing directed differentiation in certain stem cell types

  4. Resistance to cyclopentenylcytosine in murine leukemia L1210 cells.

    Science.gov (United States)

    Zhang, H; Cooney, D A; Zhang, M H; Ahluwalia, G; Ford, H; Johns, D G

    1993-12-01

    Cyclopentenyl cytosine (CPEC) exhibits oncological activity in murine and human tumor cells and has now entered Phase I clinical trials. Its mode of action as an antitumor agent appears to be inhibition by its triphosphate (CPEC-TP) of CTP synthase, the enzyme which converts UTP to CTP. In an attempt to elucidate the mechanism of resistance to CPEC, a murine leukemia cell line resistant to CPEC (L1210/CPEC) was developed by N-methyl-N-nitro-N-nitrosoguanidine-induced mutagenesis and subsequent selection by cultivation of the L1210 cells in the presence of 2 microM CPEC. Resistant clones were maintained in CPEC-free medium for 6 generations before biochemical studies were performed. The resistant clone selected for further studies was approximately 13,000-fold less sensitive to growth inhibition by CPEC than the parental cells, and the concentration of CPEC required to deplete CTP in the resistant cells was 50-fold higher than in the sensitive cells. A comparison of the kinetic properties of CTP synthase from sensitive and resistant cells indicated alteration in the properties of the enzyme from the latter; the median inhibitory concentration for CPEC-TP increased from 2 to 14 microM, Km for UTP decreased from 126 to 50 microM, and Vmax increased 12-fold from 0.2 to 2.3 nmol/mg/min. Northern blot analyses of polyadenylated RNA from the resistant and sensitive cells indicated a 3-fold increase in transcripts of the CTP synthase gene in the resistant line. Consistent with these alterations in the properties of the enzyme, the resistant cells exhibited significantly expanded CTP and dCTP pools (4- 5-fold) when compared with the sensitive cells. No change was observed, however, in the properties of uridine-cytidine kinase, the enzyme responsible for the initial phosphorylation of CPEC; despite this, however, cellular uptake of CPEC was greatly decreased, and phosphorylation of CPEC and its incorporation into RNA were 10-fold less than in the parental cells. These latter

  5. Radiation resistance evaluation of cross-linked polytetrafluoroethylene by the investigation of friction and wear behavior

    Science.gov (United States)

    Tang, Zhongfeng; Wang, Mouhua; Zhao, Yanning; Wu, Guozhong

    2011-03-01

    Radiation resistance of cross-linked polytetrafluoroethylene (XPTFE) sheets was evaluated by measuring the friction and wear properties as well as observing the morphology after γ-irradiation in air at room temperature. The wear resistance of XPTFE was confirmed to be much higher than that of virgin PTFE. The friction coefficient of XPTFE decreased with increasing dose, whereas the wear resistance remained stable until a critical dose was reached and then decreased sharply with dose. The critical dose of wear resistance was dependent on the crosslinking density or crosslinking dose of XPTFE. The radiation resistance of XPTFE improved significantly due to the formation of three-dimensional crosslinking networks by irradiation in the molten state. In addition, morphologies of the abraded debris of virgin PTFE and XPTFE were also compared and a clear difference was observed.

  6. Stomatal resistance of rice leaves as influenced by radiation intensity and air humidity

    International Nuclear Information System (INIS)

    This paper describes results of field experiments of relationships between meteorological conditions and stomatal resistance of rice leaves. The magnitude of stomatal resistance of rice leaves was measured by a porometer at important three developmental stages of rice plants. Stomatal resistance (rs) changed very clearly throughout sunny days in relation to diurnal variation in solar radiation intensity (St) and leaf air vapor concentration deficit (HD). Stomatal resistance of the adaxial surface of rice leaves was found to be the same to that of the abaxial surface in the magnitude, indicating that the water vapor fluxes at the both surfaces of rice leaves are equal with each other. The dependence of non-dimensional stomatal resistance [rs/rm·k(HD)2] on solar radiation intensity (St) was well approximated by a hyperbolic function. The relationship between HD and [rs/rm(1+St, m/St)] was expressed by a quadratic function of HD

  7. Correlation of electromagnetic radiation emitted from coal or rock to supporting resistance

    Institute of Scientific and Technical Information of China (English)

    JIA Hui-lin; WANG En-yuan; SONG Xiao-yan; ZHANG Hong-jie; LI Zhong-hui

    2009-01-01

    More accurate forecasting of rock burst might be possible from observations of electromagnetic radiation emitted in the mine. We analyzed experimental observations and field data from the Muchengjian coal mine to study the relationship between electromagnetic radiation signal intensity and stress during the fracturing of coal, or rock, and samples under load. The results show that the signal intensity is positively correlated with stress. In addition, we investigated the change in the electromagnetic radiation intensity, the supporting resistance in a real coal mine environment, and the coal or rock stress in the mining area. The data analysis indicates that: 1) electromagnetic radiation intensity can accurately reflect the distribution of stress in the mining area; and, 2) there is a correlation between electromagnetic radiation intensity and supporting resistance. The research has some practical guiding significance for rock burst forecasting and for the prevention of accidents in coal mines.

  8. Resistance to BRAF inhibitors induces glutamine dependency in melanoma cells

    Science.gov (United States)

    Baenke, Franziska; Chaneton, Barbara; Smith, Matthew; Van Den Broek, Niels; Hogan, Kate; Tang, Haoran; Viros, Amaya; Martin, Matthew; Galbraith, Laura; Girotti, Maria R.; Dhomen, Nathalie; Gottlieb, Eyal; Marais, Richard

    2016-01-01

    BRAF inhibitors can extend progression-free and overall survival in melanoma patients whose tumors harbor mutations in BRAF. However, the majority of patients eventually develop resistance to these drugs. Here we show that BRAF mutant melanoma cells that have developed acquired resistance to BRAF inhibitors display increased oxidative metabolism and increased dependency on mitochondria for survival. Intriguingly, the increased oxidative metabolism is associated with a switch from glucose to glutamine metabolism and an increased dependence on glutamine over glucose for proliferation. We show that the resistant cells are more sensitive to mitochondrial poisons and to inhibitors of glutaminolysis, suggesting that targeting specific metabolic pathways may offer exciting therapeutic opportunities to treat resistant tumors, or to delay emergence of resistance in the first-line setting. PMID:26365896

  9. Radiation-Induced Glycogen Accumulation Detected by Single Cell Raman Spectroscopy Is Associated with Radioresistance that Can Be Reversed by Metformin.

    Directory of Open Access Journals (Sweden)

    Quinn Matthews

    Full Text Available Altered cellular metabolism is a hallmark of tumor cells and contributes to a host of properties associated with resistance to radiotherapy. Detection of radiation-induced biochemical changes can reveal unique metabolic pathways affecting radiosensitivity that may serve as attractive therapeutic targets. Using clinically relevant doses of radiation, we performed label-free single cell Raman spectroscopy on a series of human cancer cell lines and detected radiation-induced accumulation of intracellular glycogen. The increase in glycogen post-irradiation was highest in lung (H460 and breast (MCF7 tumor cells compared to prostate (LNCaP tumor cells. In response to radiation, the appearance of this glycogen signature correlated with radiation resistance. Moreover, the buildup of glycogen was linked to the phosphorylation of GSK-3β, a canonical modulator of cell survival following radiation exposure and a key regulator of glycogen metabolism. When MCF7 cells were irradiated in the presence of the anti-diabetic drug metformin, there was a significant decrease in the amount of radiation-induced glycogen. The suppression of glycogen by metformin following radiation was associated with increased radiosensitivity. In contrast to MCF7 cells, metformin had minimal effects on both the level of glycogen in H460 cells following radiation and radiosensitivity. Our data demonstrate a novel approach of spectral monitoring by Raman spectroscopy to assess changes in the levels of intracellular glycogen as a potential marker and resistance mechanism to radiation therapy.

  10. Radiation-Induced Glycogen Accumulation Detected by Single Cell Raman Spectroscopy Is Associated with Radioresistance that Can Be Reversed by Metformin.

    Science.gov (United States)

    Matthews, Quinn; Isabelle, Martin; Harder, Samantha J; Smazynski, Julian; Beckham, Wayne; Brolo, Alexandre G; Jirasek, Andrew; Lum, Julian J

    2015-01-01

    Altered cellular metabolism is a hallmark of tumor cells and contributes to a host of properties associated with resistance to radiotherapy. Detection of radiation-induced biochemical changes can reveal unique metabolic pathways affecting radiosensitivity that may serve as attractive therapeutic targets. Using clinically relevant doses of radiation, we performed label-free single cell Raman spectroscopy on a series of human cancer cell lines and detected radiation-induced accumulation of intracellular glycogen. The increase in glycogen post-irradiation was highest in lung (H460) and breast (MCF7) tumor cells compared to prostate (LNCaP) tumor cells. In response to radiation, the appearance of this glycogen signature correlated with radiation resistance. Moreover, the buildup of glycogen was linked to the phosphorylation of GSK-3β, a canonical modulator of cell survival following radiation exposure and a key regulator of glycogen metabolism. When MCF7 cells were irradiated in the presence of the anti-diabetic drug metformin, there was a significant decrease in the amount of radiation-induced glycogen. The suppression of glycogen by metformin following radiation was associated with increased radiosensitivity. In contrast to MCF7 cells, metformin had minimal effects on both the level of glycogen in H460 cells following radiation and radiosensitivity. Our data demonstrate a novel approach of spectral monitoring by Raman spectroscopy to assess changes in the levels of intracellular glycogen as a potential marker and resistance mechanism to radiation therapy. PMID:26280348

  11. 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

  12. Isolation and characterization of human cells resistant to retrovirus infection

    OpenAIRE

    Somia Nikunj V; Lech Patrycja

    2007-01-01

    Abstract Background Identification of host cell proteins required for HIV-1 infection will add to our knowledge of the life cycle of HIV-1 and in the development of therapeutics to combat viral infection. We and other investigators have mutagenized rodent cells and isolated mutant cell lines resistant to retrovirus infection. Since there are differences in the efficiency of single round infection with VSVG pseudotyped HIV-1 on cells of different species, we conducted a genetic screen to isola...

  13. Isolation and characterization of human cells resistant to retrovirus infection

    OpenAIRE

    Lech, Patrycja; Somia, Nikunj V.

    2007-01-01

    Background Identification of host cell proteins required for HIV-1 infection will add to our knowledge of the life cycle of HIV-1 and in the development of therapeutics to combat viral infection. We and other investigators have mutagenized rodent cells and isolated mutant cell lines resistant to retrovirus infection. Since there are differences in the efficiency of single round infection with VSVG pseudotyped HIV-1 on cells of different species, we conducted a genetic screen to isolate human ...

  14. Collection of radiation resistant characteristics reports for instruments and materials in high dose rate environment

    International Nuclear Information System (INIS)

    This document presents the collected official reports of radiation irradiation study for the candidate materials to be used in high dose rate environment as J-PARC facility. The effect of radiation damage by loss-beam or secondary particle beam of the accelerators influences the performance and the reliability of various instruments. The knowledge on the radiation resistivity of the materials is important to estimate the life of the equipments, the maintenance interval and dose evaluation for the personnel at the maintenance period. The radiation damage consists with mechanical property, electrical property and gas-evolution property. (author)

  15. Relative responses of an X-ray-resistant hybrid cell-line and its parent line to X-irradiation, ultraviolet light, actinomycin D and cordycepin

    International Nuclear Information System (INIS)

    Using colony formation as an assay, a rat-mouse hybrid cell-line (HD1) and one of its parent lines (H4) have been studied as to their abilities to survive exposure to ionizing radiation, ultraviolet light, and the drugs actinomycin D and cordycepin. HD1 cells were more resistant than H4 to ionizing radiation, actinomycin D and cordycepin. Both cell lines responded similarly to ultraviolet light. When both cell-lines were co-treated with actinomycin D or cordycepin, the toxic effect of ionizing radiation was enhanced, whereas that of ultraviolet light (U.V.L.) was unchanged. The data suggest that RNA synthesis is more important immediately after irradiation with X-rays than with U.V.L. and that cells resistant to the toxic effect of ionizing radiation are also resistant to the toxicity induced by inhibitors of RNA synthesis. (author)

  16. Mechanisms of radiation-induced neoplastic cell transformation

    International Nuclear Information System (INIS)

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

  17. Tumour cell resistance to Aurora kinase inhibitors

    Czech Academy of Sciences Publication Activity Database

    Hrabáková, Rita; Kollareddy, M.; Martinková, Jiřina; Halada, Petr; Hajdúch, M.; Kovářová, Hana

    Liblice: Institute of Animal Physiology and Genetics AS CR, v.v.i, 2010. s. 26-26. [Informal Proteomic Meeting 2010. 09.11.2010-10.11.2010, Liblice] R&D Projects: GA MŠk LC07017 Institutional research plan: CEZ:AV0Z50450515 Keywords : drug resistance * anti-cancer therapy * proteomics Subject RIV: CE - Biochemistry

  18. Effect of curcumin on multidrug resistance in resistant human gastric carcinoma cell line SGC7901/VCR

    Institute of Scientific and Technical Information of China (English)

    Xiao-qing TANG; Hu BI; Jian-qiang FENG; Jian-guo CAO

    2005-01-01

    Aim: To investigate the reversal effects of curcumin on multidrug resistance (MDR)in a resistant human gastric carcinoma cell line. Methods: The cytotoxic effect of vincristine (VCR) was evaluated by MTT assay. The cell apoptosis induced by VCR was determined by propidium iodide (PI)-stained flow cytometry (FCM) and a morphological assay using acridine orange (AO)/ethidium bromide (EB) dual staining. P-glycoprotein (P-gp) function was demonstrated by the accumulation and efflux of rhodamine123 (Rh123) using FCM. The expression of P-gp and the activation of caspase-3 were measured by FCM using fluorescein isothiocyanate (FITC)-conjugated anti-P-gp and anti-cleaved caspase-3 antibodies, respectively.Results: Curcumin, at concentrations of 5 μmol/L, 10 μmol/L, or 20 μmol/L, had no cytotoxic effect on a parent human gastric carcinoma cell line (SGC7901) or its VCR-resistant variant cell line (SGC7901/VCR). The VCR-IC50 value of the SGC7901/VCR cells was 45 times more than that of the SGC7901cells and the SGC7901/VCR cells showed apoptotic resistance to VCR. SGC7901/VCR cells treated with 5μmol/L, 10 μmol/L, or 20 μmol/L curcumin decreased the IC50 value of VCR and promoted VCR-mediated apoptosis in a dose-dependent manner. Curcumin (10μmol/L) increased Rh 123 accumulation and inhibited the efflux of Rh 123 in S GC7901/VCR cells, but did not change the accumulation and efflux of Rh123 in SGC7901cells. P-gp was overexpressed in SGC7901/VCR cells, whereas it was downregulated after a 24-h treatment with curcumin (10 μmol/L). Resistant cells treated with 1μmol/L VCR alone showed 77% lower levels of caspase-3 activation relative to SGC7901 cells, but the activation of caspase-3 in the resistant cell line increased by 44% when cells were treated with VCR in combination with curcumin.Conclusion: Curcumin can reverse the MDR of the human gastric carcinoma SGC7901/VCR cell line. This might be associated with decreased P-gp function and expression, and the promotion of

  19. Radiation crosslinked block copolymer blends with improved impact resistance

    International Nuclear Information System (INIS)

    Polymer blends having high impact resistance after mechanical working are produced by blending together a non-elastomeric monovinylidene aromatic polymer such as polystyrene with an elastomeric copolymer, such as a block copolymer of styrene and butadiene, in the form of crosslinked, colloidal size particles

  20. Radiation-induced apoptosis in microvascular endothelial cells.

    OpenAIRE

    Langley, R. E.; Bump, E A; Quartuccio, S. G.; Medeiros, D.; Braunhut, S. J.

    1997-01-01

    The response of the microvasculature to ionizing radiation is thought to be an important factor in the overall response of both normal tissues and tumours. It has recently been reported that basic fibroblast growth factor (bFGF), a potent mitogen for endothelial cells, protects large vessel endothelial cells from radiation-induced apoptosis in vitro. Microvessel cells are phenotypically distinct from large vessel cells. We studied the apoptotic response of confluent monolayers of capillary en...

  1. Radiation up-regulated the expression of VEGF in a canine oral melanoma cell line

    International Nuclear Information System (INIS)

    To evaluate radiosensitivity and the effects of radiation on the expression of vascular endothelial growth factor (VEGF) and VEGF receptors in the canine oral melanoma cell line, TLM 1, cells were irradiated with doses of 0, 2, 4, 6, 8 and 10 Gray (Gy). Survival rates were then determined by a MTT assay, while vascular endothelial growth factor receptor (VEGFR)-1 and -2 expression was measured by flow cytometry and apoptotic cell death rates were investigated using an Annexin assay. Additionally, a commercially available canine VEGF ELISA kit was used to measure VEGF. Radiosensitivity was detected in TLM 1 cells, and mitotic and apoptotic cell death was found to occur in a radiation dose dependent manner. VEGF was secreted constitutively and significant up-regulation was observed in the 8 and 10 Gy irradiated cells. In addition, a minor portion of TLM 1 cells expressed vascular endothelial growth factor receptor (VEGFR)-1 intracellularly. VEGFR-2 was detected in the cytoplasm and was down-regulated following radiation with increasing dosages. In TLM 1 cells, apoptosis plays an important role in radiation induced cell death. It has also been suggested that the significantly higher VEGF production in the 8 and 10 Gy group could lead to tumour resistance. (author)

  2. Radiation damage and repair in cells and cell components. Part 2. Physical radiations and biological significance. Final report

    International Nuclear Information System (INIS)

    The report comprises a teaching text, encompassing all physical radiations likely to be of biological interest, and the relevant biological effects and their significance. Topics include human radiobiology, delayed effects, radiation absorption in organisms, aqueous radiation chemistry, cell radiobiology, mutagenesis, and photobiology

  3. Epigenetic cell response to an influence of ionizing radiation

    International Nuclear Information System (INIS)

    Importance of radiation modification of epigenetic activity in the general mechanism of radiobiological reactions is proved. Inheritable epigenetic changes induced by irradiation are one of the basic reasons of formation of the remote radiation pathology. It is noted that epigenetic inheritable changes of cells have the determined character distinguishing them mutation changes, being individual and not directed. It is underlined the ability of ionizing radiation to modify level of spontaneous genetic instability inherited in a number of cell generations on epigenetic mechanism

  4. Space solar cells - High efficiency and radiation damage

    Science.gov (United States)

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

    1980-01-01

    The proceedings of the Third Solar Cell High Efficiency and Radiation Damage Meeting are outlined. The topics covered included high efficiency silicon solar cells, silicon solar cell radiation damage, GaAs solar cell performance, and 30 percent conversion devices. The study of radiation damage from a fundamental defect-centered basis is discussed and evaluated as a focus of future work. 18% AM0 efficiency and 0.7 V open-circuit voltages are designated as achievable goals for silicon solar cells, and the potential for 30% AM0 efficiencies from monolithic tandem cell designs without sunlight concentration is noted. In addition to its potential for 20% AM0 efficiencies, the GaAs cell offers the possibility of a radiation-insensitive power supply when operated at temperatures near 200 C.

  5. Radiation resistance of carbon composites (carbon-carbon type)

    International Nuclear Information System (INIS)

    Active (in-channel) and passive (post-irradiation) methods have been used to study how the dimensions and electrical resistance of the composites KUP-VM, Termar-TD, and carboxylar change at temperatures up to 2100-2300 K and a fluence of up to 3·1021 n/cm2. The change in the size and resistivity, determined by both methods, are almost the same, i.e., there are no dynamic effects. The dimensions of the samples depend in an involved way on the irradiation temperature, neutron fluence, and structure of the material. The samples retained their integrity under the irradiation conditions of the tests. 8 refs., 4 figs., 1 tab

  6. Investigation of radiation-resistant polyolefin materials used in power reactors

    International Nuclear Information System (INIS)

    It was forecasted that China would spend more than 40 billion US dollars on power reactors with a total of 27 million-kilowatt generation by 2020. This will require a huge quantity of cables and heat-shrinkable materials in the nuclear power stations, as an average GW nuclear power station needs one or two million US dollars of cables and accessories with radiation-resistant insulations. These materials must be heat resistant, radiation resistant, LOCA resistant, low smoke, halogen-free and flame retardant. Typical performance requirements are as follows: 1) Thermal aging experiments: 300 h at 138 degree C according to US standard for 40 years lifetime in power reactors. 2) Irradiation experiments: irradiated by 60Co γ-rays after aging to 700 kGy under mild surrounding conditions and 1500 kGy under rigor conditions, according to US standard. 3) LOCA-Helb experimental simulation: the cables are subjected to repeated tests in a vessel under regulated temperature and vapor pressure in different period of time, with simultaneous spraying of chemical solution (typically 1.5% boracic acid solution of pH=10.5 adjusted by NaOH) in a flux of 34.2 L·min-1·m-2 in the horizontal projection surface. 4) Flame retardant: the oxygen index of low smoke and halogen-free materials is ≥25 for cable insulation, and ≥27 for cable sheath. Our research is aimed at achieving the aging resistance performance with radiation crosslinking. Polyethylene and ethylene-propylene rubber are mixed with selected radiation-resistant reagents and the radiation resistant mechanisms are investigated. In addition, halogen-free flame retardant materials and surface treatment of the inorganic reagents are studied for making cables and heat-shrinkable cable accessories for nuclear power applications. They will meet technical requirements of the LOCA test, with desirable performances on low smoke halogen-free and flame retardant. (authors)

  7. Mitomycin resistance in mammalian cells expressing the bacterial mitomycin C resistance protein MCRA

    OpenAIRE

    Belcourt, Michael F.; Penketh, Philip G.; Hodnick, William F.; Johnson, David A.; David H Sherman; Rockwell, Sara; Sartorelli, Alan C.

    1999-01-01

    The mitomycin C-resistance gene, mcrA, of Streptomyces lavendulae produces MCRA, a protein that protects this microorganism from its own antibiotic, the antitumor drug mitomycin C. Expression of the bacterial mcrA gene in mammalian Chinese hamster ovary cells causes profound resistance to mitomycin C and to its structurally related analog porfiromycin under aerobic conditions but produces little change in drug sensitivity under hypoxia. The mitomycins are prodrugs that are enzymatically reduc...

  8. Taxotere resistance in SUIT Taxotere resistance in pancreatic carcinoma cell line SUIT 2 and its sublines

    Institute of Scientific and Technical Information of China (English)

    Bin Liu; Edgar Staren; Takeshi Iwamura; Hubert Appert; John Howard

    2001-01-01

    AIM: To investigate the specific mechanisms of intrinsic and acquired resistance to taxotere (TXT) in pancreatic adenocarcinoma (PAC). METHODS: MTT assay was used to detect the sensitivity of PAC cell line SUIT-2 and its sublines (S-007, S-013, S-020,S-028 and TXT selected SUIT-2 cell line, S2/TXT) to TXT.Mdr1 (P-gp), multidrug resistance associated protein (MRP), lung resistance protein (LRP) and β-tubulin isotype gene expressions were detected by RT-PCR. The functionality of P-gp and MRP was tested using their specific blocker verapamil ( Ver ) and indomethacin ( IMC ),respectively. The transporter activity of P-gp was also confirmed by Rhodamine 123 accumulation assay. RESULTS: S-020 and S2/TXT were found to be significantly resistant to TXT(19 and 9.5-fold to their parental cell line SUIT-2, respectively ). RT-PCR demonstrated strong expression of Mdr1 in these two cell lines, but weaker expression or no expression in other cells lines. MRP and LRP expressions were found in most of these cell lines. The TXT-resistance in S2-020 and S2/TXT could be reversed almost completely by Ver, but not by IMC. Flow cytometry showed that Ver increased the accumulation of Rhodamine-123 in these two cell lines. Compared with S-020 and SUIT-2,the levels of β-tubulin isotype II, III expreesions in S-2/TXTwere increased remarkably. CONCLUSION: The both intrinsic and acquired TXT-related drugresistance in these PAC cell lines is mainly mediated by P-gp, but had no relationship to MRP and LRP expressions.The increases of β-tubulin isotype II, III might be collateral changes that occur when the SUIT-2 cells are treated with TXT.

  9. The importance of bystander effects in radiation therapy in melanoma skin-cancer cells and umbilical-cord stromal stem cells

    International Nuclear Information System (INIS)

    Purpose: To examine direct and bystander radiation-induced effects in normal umbilical-cord stromal stem cell (HCSSC) lines and in human cancer cells. Materials and methods: The UCSSC lines used in this study were obtained in our laboratory. Two cell lines (UCSSC 35 and UCSSC 37) and two human melanoma skin-cancer cells (A375 and G361) were exposed to ionizing radiation to measure acute radiation-dosage cell-survival curves and radiation-induced bystander cell-death response. Normal cells, although extremely sensitive to ionizing radiation, were resistant to the bystander effect whilst tumor cells were sensitive to irradiated cell-conditioned media, showing a dose–response relationship that became saturated at relatively low doses. We applied a biophysical model to describe bystander cell-death through the binding of a ligand to the cells. This model allowed us to calculate the maximum cell death (χmax) produced by the bystander effect together with its association constant (KBy) in terms of dose equivalence (Gy). The values obtained for KBy in A375 and G361 cells were 0.23 and 0.29 Gy, respectively. Conclusion: Our findings help to understand how anticancer therapy could have an additional decisive effect in that the response of sub-lethally hit tumor cells to damage might be required for therapy to be successful because the survival of cells communicating with irradiated cells is reduced.

  10. Tcf3 and cell cycle factors contribute to butyrate resistance in colorectal cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Chiaro, Christopher, E-mail: cchiaro@tcmedc.org [Department of Basic Sciences, The Commonwealth Medical College, 525 Pine Street, Scranton, PA 18509 (United States); Lazarova, Darina L., E-mail: dlazarova@tcmedc.org [Department of Basic Sciences, The Commonwealth Medical College, 525 Pine Street, Scranton, PA 18509 (United States); Bordonaro, Michael, E-mail: mbordonaro@tcmedc.org [Department of Basic Sciences, The Commonwealth Medical College, 525 Pine Street, Scranton, PA 18509 (United States)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer We investigate mechanisms responsible for butyrate resistance in colon cancer cells. Black-Right-Pointing-Pointer Tcf3 modulates butyrate's effects on Wnt activity and cell growth in resistant cells. Black-Right-Pointing-Pointer Tcf3 modulation of butyrate's effects differ by cell context. Black-Right-Pointing-Pointer Cell cycle factors are overexpressed in the resistant cells. Black-Right-Pointing-Pointer Reversal of altered gene expression can enhance the anti-cancer effects of butyrate. -- Abstract: Butyrate, a fermentation product of dietary fiber, inhibits clonal growth in colorectal cancer (CRC) cells dependent upon the fold induction of Wnt activity. We have developed a CRC cell line (HCT-R) that, unlike its parental cell line, HCT-116, does not respond to butyrate exposure with hyperactivation of Wnt signaling and suppressed clonal growth. PCR array analyses revealed Wnt pathway-related genes, the expression of which differs between butyrate-sensitive HCT-116 CRC cells and their butyrate-resistant HCT-R cell counterparts. We identified overexpression of Tcf3 as being partially responsible for the butyrate-resistant phenotype, as this DNA-binding protein suppresses the hyperinduction of Wnt activity by butyrate. Consequently, Tcf3 knockdown in HCT-R cells restores their sensitivity to the effects of butyrate on Wnt activity and clonal cell growth. Interestingly, the effects of overexpressed Tcf3 differ between HCT-116 and HCT-R cells; thus, in HCT-116 cells Tcf3 suppresses proliferation without rendering the cells resistant to butyrate. In HCT-R cells, however, the overexpression of Tcf3 inhibits Wnt activity, and the cells are still able to proliferate due to the higher expression levels of cell cycle factors, particularly those driving the G{sub 1} to S transition. Knowledge of the molecular mechanisms determining the variable sensitivity of CRC cells to butyrate may assist in developing approaches that

  11. Tcf3 and cell cycle factors contribute to butyrate resistance in colorectal cancer cells

    International Nuclear Information System (INIS)

    Highlights: ► We investigate mechanisms responsible for butyrate resistance in colon cancer cells. ► Tcf3 modulates butyrate’s effects on Wnt activity and cell growth in resistant cells. ► Tcf3 modulation of butyrate’s effects differ by cell context. ► Cell cycle factors are overexpressed in the resistant cells. ► Reversal of altered gene expression can enhance the anti-cancer effects of butyrate. -- Abstract: Butyrate, a fermentation product of dietary fiber, inhibits clonal growth in colorectal cancer (CRC) cells dependent upon the fold induction of Wnt activity. We have developed a CRC cell line (HCT-R) that, unlike its parental cell line, HCT-116, does not respond to butyrate exposure with hyperactivation of Wnt signaling and suppressed clonal growth. PCR array analyses revealed Wnt pathway-related genes, the expression of which differs between butyrate-sensitive HCT-116 CRC cells and their butyrate-resistant HCT-R cell counterparts. We identified overexpression of Tcf3 as being partially responsible for the butyrate-resistant phenotype, as this DNA-binding protein suppresses the hyperinduction of Wnt activity by butyrate. Consequently, Tcf3 knockdown in HCT-R cells restores their sensitivity to the effects of butyrate on Wnt activity and clonal cell growth. Interestingly, the effects of overexpressed Tcf3 differ between HCT-116 and HCT-R cells; thus, in HCT-116 cells Tcf3 suppresses proliferation without rendering the cells resistant to butyrate. In HCT-R cells, however, the overexpression of Tcf3 inhibits Wnt activity, and the cells are still able to proliferate due to the higher expression levels of cell cycle factors, particularly those driving the G1 to S transition. Knowledge of the molecular mechanisms determining the variable sensitivity of CRC cells to butyrate may assist in developing approaches that prevent or reverse butyrate resistance.

  12. Mechanism for radiation damage resistance in yttrium oxide dispersion strengthened steels

    Science.gov (United States)

    Brodrick, J.; Hepburn, D. J.; Ackland, G. J.

    2014-02-01

    ODS steels based on yttrium oxide have been suggested as potential fusion reactor wall materials due to their observed radiation resistance properties. Presumably this radiation resistance can be related to the interaction of the particle with vacancies, self-interstitial atoms (SIAs) and other radiation damage debris. Density functional theory has been used to investigate this at the atomic scale. Four distinct interfaces, some based on HRTEM observations, between iron and yttrium oxide were investigated. It is been shown that the Y2O3-Fe interface acts as a strong trap with long-range attraction for both interstitial and vacancy defects, allowing recombination without altering the interface structure. The catalytic elimination of defects without change to the microstructure explains the improved behaviour of ODS steels with respect to radiation creep and swelling.

  13. Radiation resistance of the natural microbial population in buffer materials

    Energy Technology Data Exchange (ETDEWEB)

    Stroes-Gascoyne, S.; Lucht, L.M.; Borsa, J.; Delaney, T.L.; Haveman, S.A.; Hamon, C.J. [AECL Research, Pinawa, Manitoba (Canada). Whiteshell Labs.

    1995-12-31

    The radiation sensitivity of naturally occurring microorganisms in buffer materials was investigated as well as the sensitivity of Bacillus subtillis spores and Acinetobacter radioresistens in a buffer matrix. The D{sub 10} values obtained in these radiation experiments varied from 0.34 to 1.68 kGy and it was calculated that the surface of a nuclear fuel waste container would be sterilized in 9 to 33 d after emplacement, depending on the type of container, and the initial bioburden. This suggests that formation of biofilms and microbially influenced corrosion would not be of concern of some time after emplacement. The results also indicated that sterilization throughout a 25 cm thick buffer layer is unlikely and that repopulation of the container surface after some time is a possibility, depending on the mobility of microbes in compacted buffer material.

  14. Radiation resistance of the natural microbial population in buffer materials

    International Nuclear Information System (INIS)

    The radiation sensitivity of naturally occurring microorganisms in buffer materials was investigated as well as the sensitivity of Bacillus subtillis spores and Acinetobacter radioresistens in a buffer matrix. The D10 values obtained in these radiation experiments varied from 0.34 to 1.68 kGy and it was calculated that the surface of a nuclear fuel waste container would be sterilized in 9 to 33 d after emplacement, depending on the type of container, and the initial bioburden. This suggests that formation of biofilms and microbially influenced corrosion would not be of concern of some time after emplacement. The results also indicated that sterilization throughout a 25 cm thick buffer layer is unlikely and that repopulation of the container surface after some time is a possibility, depending on the mobility of microbes in compacted buffer material

  15. Radiation resistance testing of high-density polyethylene

    International Nuclear Information System (INIS)

    Mechanical tests following gamma inrradiation and creep tests during irradiation have been conducted on high-density polyethylene (HDPE) to assess the adequacy of this material for use in high-integrity containers (HICs). These tests were motivated by experience in nuclear power plants in which polyethylene electrical insulation detoriorated more rapidly than expected due to radiation-induced oxidation. This suggested that HDPE HICs used for radwaste disposal might degrade more rapidly than would be expected in the absence of the radiation field. Two types of HDPE, a highly cross-linked rotationally molded material and a non-cross-linked blow molded material, were used in these tests. Gamma-ray irradiations were performed at several dose rates in environments of air, Barnwell and Hanford backfill soils, and ion-exchange resins. The results of tensile and bend testing on these materials following irradiation will be presented along with preliminary results on creep during irradiation

  16. Altruistic cell suicide in relation to radiation hormesis

    International Nuclear Information System (INIS)

    The high radiosensitivity to killing of undifferentiated primordial cells (Bergonie and Tribondeau 1906) can be described as a manifestation of the suicide of injured cells for the benefit of an organism as a whole if their suicide stimulates proliferation of healthy cells to replace them, resulting in complete elimination of injury. This process is called cell-replacement repair, to distinguish it from DNA repair which is rarely complete. 'Cell suicide', 'programmed death' and 'apoptosis' are terms used for the same type of active cell death. Cell suicide is not always altruistic. Altruistic suicide in Drosophila, mice, humans, plants, and E. coli is reviewed in this paper to illustrate its widely different facets. The hypothesis that in animals, radiation hormesis results from altruistic cell suicide is proposed. This hypothesis can explain the hormetic effect of low doses of radiation on the immune system in mice. In contrast, in plants, radiation hormesis seems to be mainly due to non-altruistic cell death. (author)

  17. Effect of Ni content on thermal and radiation resistance of VVER RPV steel

    Science.gov (United States)

    Shtrombakh, Ya. I.; Gurovich, B. A.; Kuleshova, E. A.; Frolov, A. S.; Fedotova, S. V.; Zhurko, D. A.; Krikun, E. V.

    2015-06-01

    In this paper thermal stability and radiation resistance of VVER-type RPV steels for pressure vessels of advanced reactors with different nickel content were studied. A complex of microstructural studies and mechanical tests of the steels in different states (after long thermal exposures, provoking embrittling heat treatment and accelerated neutron irradiation) was carried out. It is shown that nickel content (other things being equal) determines the extent of materials degradation under influence of operational factors: steels with a lower nickel concentration demonstrate a higher thermal stability and radiation resistance.

  18. Effect of Ni content on thermal and radiation resistance of VVER RPV steel

    International Nuclear Information System (INIS)

    In this paper thermal stability and radiation resistance of VVER-type RPV steels for pressure vessels of advanced reactors with different nickel content were studied. A complex of microstructural studies and mechanical tests of the steels in different states (after long thermal exposures, provoking embrittling heat treatment and accelerated neutron irradiation) was carried out. It is shown that nickel content (other things being equal) determines the extent of materials degradation under influence of operational factors: steels with a lower nickel concentration demonstrate a higher thermal stability and radiation resistance

  19. Recent Advances in Electrical Resistance Preheating of Aluminum Reduction Cells

    Science.gov (United States)

    Ali, Mohamed Mahmoud; Kvande, Halvor

    2016-06-01

    ABSTRACT There are two mainpreheating methods that are used nowadays for aluminum reduction cells. One is based on electrical resistance preheating with a thin bed of small coke and/or graphite particles between the anodes and the cathode carbon blocks. The other is flame preheating, where two or more gas or oil burners are used. Electrical resistance preheating is the oldest method, but is still frequently used by different aluminum producers. Many improvements have been made to this method by different companies over the last decade. In this paper, important points pertaining to the preparation and preheating of these cells, as well as measurements made during the preheating process and evaluation of the performance of the preheating, are illustrated. The preheating times of these cells were found to be between 36 h and 96 h for cell currents between 176 kA and 406 kA, while the resistance bed thickness was between 13 mm and 60 mm. The average cathode surface temperature at the end of the preheating was usually between 800°C and 950°C. The effect of the preheating methods on cell life is unclear and no quantifiable conclusions can be drawn. Some works carried out in the mathematical modeling area are also discussed. It is concluded that there is a need for more studies with real situations for preheated cells on the basis of actual measurements. The expected development in electrical resistance preheating of aluminum reduction cells is also summarized.

  20. Advanced technology lunar telescopes III. Radiation resistant detectors

    International Nuclear Information System (INIS)

    A practical lunar telescope requires high resolution imaging array detectors that are immune to (or can be easily shielded from) solar flare particle radiation and cosmic rays. Charge-coupled devices (CCDs), the detectors of choice for ground-based applications, fall short in this respect because of their high susceptibility to radiation induced bulk traps and loss of charge transfer efficiency (CTE). Blooming in CCDs also limits the dynamic range and degrades resolution, while the well known red leak problem hinders observations in the ultraviolet. The authors describe an ongoing program at NASA GSFC to develop intensified random-access Charge-Injection Devices (CIDs), a new generation of space uv detectors which do not have the shortcomings of CCDs. CIDs, like CCDs, are silicon array detectors. Unlike CCDs, however, CIDs have more than 100x greater tolerance to ionizing particle radiation. Since CIDs do not transfer charge, CTE degradation has very little effect on the overall sensitivity and noise level. CIDs can perform extremely fast windowing of selected regions of interest with high signal levels (e.g. bright cores of galaxies or strong emission lines, etc) while monitoring the remainder of the array at lower rates. This selective readout ability plus the lack of blooming give CIDs a high dynamic range of operation but with minimal demands on the memory storage and telemetry data bandwidth. The authors demonstrate the operation of a row-windowing CID and discuss the potential applications of these devices to astronomical research from the moon

  1. Evolution of radiation resistant hollow fibers membranes for nuclear

    International Nuclear Information System (INIS)

    We have evaluated hollow fiber supported liquid membrane (HFSLM) technique for the separation of actinides, fission products and other valuables from the nuclear waste solutions. In this technique, ligand responsible for separation of metal ion is held in tiny pores of membrane. Any drastic change as a consequence of irradiation, like change in pore size, change in hydrophobicity of polymeric material can be fatal for separation process as it may lead dislodging of carrier ligands from the pores. It was therefore needed to study the irradiation stability of hollow fibers. We have earlier showed that polypropylene fibers were stable up to 500 radiation dose and we therefore need to look into other options. In the present work, hollow fiber membranes made from polyether ether ketone (PEEK), polysulphone (PS). Polymers were evaluated for their radiation stability after exposing to varying absorbed dose of gamma radiation. The hollow fibers were irradiated to 100 KGy, 200 KGy, 500 KGy and 1000 KGy and its changes in hydrophobicity were measured using contact angle measurement studies

  2. Fabrication and characterization of radiation-resistant LDPE/MWCNT nanocomposites

    International Nuclear Information System (INIS)

    Highlight: • Well-mixed LDPE/MWCNT nanocomposites were prepared through a melt blending. • The LDPE/MWCNT nanocomposites showed a higher radiation-resistance than the pure LDPE. • This improvement could be due to the presence of radical scavenging MWNCT. • The lifetime of the LDPE/MWCNT was much longer than that of the pure LDPE. -- Abstract: In this study, multi-walled carbon nanotube (MWCNT)-reinforced low density polyethylene (LDPE) nanocomposites were fabricated to improve the radiation resistance of LDPE. LDPE nanocomposites with various compositions prepared through a melt blending were irradiated by γ-rays at doses ranging from 50 to 500 kGy. The resulting nanocomposites were investigated in terms of their morphology, tensile property, activation energy, oxidation stability, thermal stability, and lifetime. Based on the results of the field emission scanning electron microscope (FE-SEM) analysis, MWCNTs were found to be well-dispersed in the LDPE matrix even at 3 wt.%, and no radiation-induced morphological changes were observed. The analytic results of the tensile property, oxidative stability, and activation energy revealed that the LDPE/MWCNT nanocomposites exhibited a higher radiation resistance in comparison to the pure LDPE, which was dependent on the MWCNT content. Moreover, based on the lifetime prediction, the lifetime of the LDPE/MWCNT was much longer than that of the pure LDPE. This improved radiation resistance can be ascribed to the incorporation of the radical scavenging MWCNT nanofillers into the LDPE matrix

  3. Fabrication and characterization of radiation-resistant LDPE/MWCNT nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Chan-Hee; Lee, Dong-Hoon; Hwang, In-Tae; Im, Don-Sun; Shin, Junhwa; Kang, Phil-Hyun [Research Division for Industry and Environment, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Choi, Jae-Hak, E-mail: jaehakchoi@cnu.ac.kr [Research Division for Industry and Environment, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 580-185 (Korea, Republic of); Department of Polymer Science and Engineering, Chungnam National University, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

    2013-07-15

    Highlight: • Well-mixed LDPE/MWCNT nanocomposites were prepared through a melt blending. • The LDPE/MWCNT nanocomposites showed a higher radiation-resistance than the pure LDPE. • This improvement could be due to the presence of radical scavenging MWNCT. • The lifetime of the LDPE/MWCNT was much longer than that of the pure LDPE. -- Abstract: In this study, multi-walled carbon nanotube (MWCNT)-reinforced low density polyethylene (LDPE) nanocomposites were fabricated to improve the radiation resistance of LDPE. LDPE nanocomposites with various compositions prepared through a melt blending were irradiated by γ-rays at doses ranging from 50 to 500 kGy. The resulting nanocomposites were investigated in terms of their morphology, tensile property, activation energy, oxidation stability, thermal stability, and lifetime. Based on the results of the field emission scanning electron microscope (FE-SEM) analysis, MWCNTs were found to be well-dispersed in the LDPE matrix even at 3 wt.%, and no radiation-induced morphological changes were observed. The analytic results of the tensile property, oxidative stability, and activation energy revealed that the LDPE/MWCNT nanocomposites exhibited a higher radiation resistance in comparison to the pure LDPE, which was dependent on the MWCNT content. Moreover, based on the lifetime prediction, the lifetime of the LDPE/MWCNT was much longer than that of the pure LDPE. This improved radiation resistance can be ascribed to the incorporation of the radical scavenging MWCNT nanofillers into the LDPE matrix.

  4. INFLUENCE OF INCUBATION TIME, GAMMA RAYS AND ELECTRON BEAM ON RADIATION RESISTANCE OF SOME SELECTED PATHOGENS

    International Nuclear Information System (INIS)

    The effect of different growth phases on the radiation resistance, antibiotic susceptibility and pathogenicity of certain selected pathogens (Escherichia coli, Candida albicans and Staphylococcus aureus) was studied in mice. The obtained results showed that Escherichia coli was slightly more resistant to gamma radiation in 18 h than 24 h or 48 h but it was relatively more resistant to electron beam in 24 h and 48 h than 18 h. Candida albicans showed radiation resistance nearly the same in all incubation times in the case of gamma radiation while for electron beam, its radiation resistance was slightly more in 24 h and 48 h than in 18 h. On the other hand, Staphylococcus aureus recorded much more resistance to gamma radiation in the 48 h than in 24 h or 18 h whereas in the case of electron beam, it was slightly more resistant in 18 h than in 24 h and 48 h.The antibiotic susceptibility of Escherichia coli reported that the exposure to gamma radiation at 3 kGy and electron beam at 6 kGy increase the susceptibility to the nalidixic acid and nitrofurantoin. When Candida albicans was exposed to 3 kGy gamma radiation and 6 kGy electron beam, the same sensitivity to nystatin was observed in comparison with the unexposed one while the sensitivity of Staphylococcus aureus to some antibiotics (amoxicillin, nitrofurantoin and tetracycline) was decreased after exposure to gamma radiation at 0.75 and 2 kGy and electron beam at 6 kGy, but for other antibiotics (trimethoprim/ sulfamethoxazole), the sensitivity was increased at 6 kGy electron beam.The lethality percent recorded after the oral ingestion of the mice with the unexposed Escherichia coli and Candida albicans were 25% and 100%, respectively, and for 6 kGy exposure to electron beam was 0% . The cotaneous disease and abscesses caused by the intradermal injection of the mice with unexposed Staphylococcus aureus was 75% and for 6 kGy exposure to electron beam was 25%.

  5. Drug Resistance and Cancer Stem Cells

    OpenAIRE

    Fonseca, João Pedro Couto

    2012-01-01

    O cancro do pulmão é a principal causa de morte por cancro a nível mundial. Apesar do crescente conhecimento sobre os mecanismos subjacentes ao processo tumorigénico não se tem observado alteração significativa na sobrevivência dos pacientes. É, por isso, urgente encontrar novas estratégias terapêuticas que visem superar a resistência, tanto intrínseca como extrínseca, observada com a quimioterapia corrente. Os tumores são caracterizados pela sua heterogeneidade celular, devido à coexistên...

  6. Targeting TRPM2 Channels Impairs Radiation-Induced Cell Cycle Arrest and Fosters Cell Death of T Cell Leukemia Cells in a Bcl-2-Dependent Manner

    Directory of Open Access Journals (Sweden)

    Dominik Klumpp

    2016-01-01

    Full Text Available Messenger RNA data of lymphohematopoietic cancer lines suggest a correlation between expression of the cation channel TRPM2 and the antiapoptotic protein Bcl-2. The latter is overexpressed in various tumor entities and mediates therapy resistance. Here, we analyzed the crosstalk between Bcl-2 and TRPM2 channels in T cell leukemia cells during oxidative stress as conferred by ionizing radiation (IR. To this end, the effects of TRPM2 inhibition or knock-down on plasma membrane currents, Ca2+ signaling, mitochondrial superoxide anion formation, and cell cycle progression were compared between irradiated (0–10 Gy Bcl-2-overexpressing and empty vector-transfected Jurkat cells. As a result, IR stimulated a TRPM2-mediated Ca2+-entry, which was higher in Bcl-2-overexpressing than in control cells and which contributed to IR-induced G2/M cell cycle arrest. TRPM2 inhibition induced a release from G2/M arrest resulting in cell death. Collectively, this data suggests a pivotal function of TRPM2 in the DNA damage response of T cell leukemia cells. Apoptosis-resistant Bcl-2-overexpressing cells even can afford higher TRPM2 activity without risking a hazardous Ca2+-overload-induced mitochondrial superoxide anion formation.

  7. Effects of low dose gamma radiation on the early growth of red pepper and the resistance to subsquent high dose of radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. S.; Baek, M. H.; Kim, D. H.; Lee, Y. K. [KAERI, Taejon (Korea, Republic of); Lee, Y. B. [Chungnam National Univ., Taejon (Korea, Republic of)

    2001-05-01

    Red pepper (capsicum annuum L. cv. Jokwang and cv. Johong) seeds were irradiated with the dose of 0{approx}50 Gy to investigated the effect of the low dose gamma radiation on the early growth and resistance to subsequent high dose of radiation. The effect of the low dose gamma radiation on the early growth and resistance to subsequenct high dose of radiation were enhanced in Johong cultivar but not in Jokwang cultivar. Germination rate and early growth of Johong cultivar were noticeably increased at 4 Gy-, 8 Gy- and 20 Gy irradiation group. Resistance to subsequent high dose of radiation of Johong cultivar were increased at almost all of the low dose irradiation group. Especially it was highest at 4 Gy irradiation group. The carotenoid contents and enzyme activity on the resistance to subsequent high dose of radiation of Johong cultivar were increased at the 4 Gy and 8 Gy irradiation group.

  8. Effects of radiation and chemical substances on cells and organism

    International Nuclear Information System (INIS)

    The book treats the radiation chemistry part of biophysics and applied biophysics in the sphere of ionizing radiation. Discussed are the concepts of radiation units and radioactivity units and the relative biological efficiency. The effects of ionizing and UV radiations are analyzed at the level of macromolecular changes. Chapters dealing with genetic radiation effects discuss the effects at the cellular level with respect to cell proliferation. All these problems are used to illustrate the effect on the organism as a whole. The chapters on applied biophysics deal with the indications of radiation and chemical damage, sensitivity of cells and the organism, and the study and influencing of growth at the cellular level. The concluding chapter is devoted to the environmental impact of radiation. (J.P.)

  9. Reduced membrane protein associated with resistance of human squamous carcinoma cells to methotrexate and cis-platinum.

    Science.gov (United States)

    Bernal, S D; Speak, J A; Boeheim, K; Dreyfuss, A I; Wright, J E; Teicher, B A; Rosowsky, A; Tsao, S W; Wong, Y C

    1990-06-01

    A membrane protein recognized by monoclonal antibody SQM1 was identified in human squamous carcinomas, including those originating in the head and neck (SqCHN), lung and cervix. Cell lines derived from SqCHN of previously untreated patients expressed high amounts of this protein. In contrast, many cell lines established from SqCHN of patients previously treated with chemotherapy and/or radiation showed diminished amounts of this SQM1 protein. The expression of SQM1 antigen was determined in several SqCHN cell lines made resistant by exposure to methotrexate (MTX) in vitro. The parent cell lines all exhibited strong binding to SQM1 antibody. The MTX-resistant sublines showed much lower membrane binding of SQM1. The lowest SQM1 reactivity was found in cell lines with high resistance to MTX and with diminished rate of MTX transport. Some highly MTX-resistant cell lines which had high levels of dihydrofolate reductase, but which retained a high rate of MTX transport, also retained high levels of SQM1 binding. Reduced SQM1 protein was also found in SqCHN cells which developed resistance to the alkylating drug cis-latinum (CDDP) and which showed reduced membrane transport of CDDP. Cell growth kinetics and non-specific antigenic shifts were not responsible for the differences in SQM1 binding between the parent cell lines and their drug-resistant sublines. The finding of a novel protein which is reduced in cells resistant to MTX and CDDP could contribute to our understanding of the basic mechanisms of drug resistance. By detecting SQM1 protein in clinical specimens, it may be possible to monitor the development of drug resistance in tumors. PMID:2195318

  10. Subcurative radiation significantly increases cell proliferation, invasion, and migration of primary glioblastoma multiforme in vivo

    Directory of Open Access Journals (Sweden)

    Adarsh Shankar

    2014-03-01

    Full Text Available Tumor cell proliferation, infiltration, migration, and neovascularization are known causes of treatment resistance in glioblastoma multiforme (GBM. The purpose of this study was to determine the effect of radiation on the growth characteristics of primary human GBM developed in a nude rat. Primary GBM cells grown from explanted GBM tissues were implanted orthotopically in nude rats. Tumor growth was confirmed by magnetic resonance imaging on day 77 (baseline after implantation. The rats underwent irradiation to a dose of 50 Gy delivered subcuratively on day 84 postimplantation (n = 8, or underwent no radiation (n = 8. Brain tissues were obtained on day 112 (nonirradiated or day 133 (irradiated. Immunohistochemistry was performed to determine tumor cell proliferation (Ki-67 and to assess the expression of infiltration marker (matrix metalloproteinase-2, MMP-2 and cell migration marker (CD44. Tumor neovascularization was assessed by microvessel density using von-Willebrand factor (vWF staining. Magnetic resonance imaging showed well-developed, infiltrative tumors in 11 weeks postimplantation. The proportion of Ki-67-positive cells in tumors undergoing radiation was (71+/- 15% compared with (25 +/- 12% in the nonirradiated group (P = 0.02. The number of MMP-2-positive areas and proportion of CD44-positive cells were also high in tumors receiving radiation, indicating great invasion and infiltration. Microvessel density analysis did not show a significant difference between nonirradiated and irradiated tumors. Taken together, we found that subcurative radiation significantly increased proliferation, invasion, and migration of primary GBM. Our study provides insights into possible mechanisms of treatment resistance following radiation therapy for GBM.

  11. Interactions between carbo-platin, cisplatin and ionising radiation in an human ovarian cancer cell line

    International Nuclear Information System (INIS)

    Cisplatin (CDDP) and radiotherapy are frequently used concomitantly in the treatment of various malignant conditions. Because of its toxicity, cisplatin tends to be replaced by carbo-platin (CBDCA) in several indications. Available data regarding the combined effects of cisplatin and carbo-platin with ionising radiation are contradictory. Various concentrations of cisplatin and carbo-platin and various timing of association with radiation have been tested in vitro in a human ovarian cancer cell line. The parental cell line (AOvC-0) and a cisplatin-resistant stable sub-line (AOvC-CDDP/O) (De Pooter et al., Cn Res, 1991) were exposed to carbo-platin (2.5, 5 and 10 M) and to CDDP (1, 2.5 and 5 M), 16 h and 4 h before and 4 h and 16 h after irradiation, respectively. Cell survival was evaluated by a classical clonogenic assay. Exposure of AOvC-0 to 5M CBDCA and of AOvC-CDDDP/O to 10 M CBDCA, before or shortly after radiation exposure, increased cell lethality in a clear supra-additive way, with the highest DEF in the shoulder region of the survival curve and at radiation doses relevant to clinical radiotherapy. In the sensitive cell line, 5 M carbo-platin resulted in an additional lethality equivalent to 4.5 Gy; in the resistant cells, 10M carbo-platin was equivalent to 3.6 Gy. Replacing carbo-platin by cisplatin in an identical set-up demonstrated exclusively simple additivity (DEF = 1). These data suggest that carbo-platin and cisplatin delivered at equi-toxic doses interact with radiation a different way and that, in the present set-up, only carbo-platin enhanced the effects of radiation. Carbo-platin might consequently be a better candidate than cisplatin in some concomitant combinations with radiotherapy. (authors)

  12. Stem cell-based therapies for acute radiation syndrome

    International Nuclear Information System (INIS)

    Exposure to high doses of ionizing radiation in the event of accidental or intentional incident such as nuclear/radiological terrorism can lead to debilitating injuries to multiple organs resulting in death within days depending on the amount of radiation dose and the quality of radiation. Unfortunately, there is not a single FDA-licensed drug approved against acute radiation injury. The RadStem Center for Medical Countermeasures against Radiation (RadStem CMGR) program at Einstein is developing stem cell-based therapies to treat acute radiation syndrome (ARS). We have demonstrated that intravenous transplantation of bone marrow-derived and adipose-derived stromal cells, consisting of a mixture of mesenchymal, endothelial and myeloid progenitors can mitigate mice exposed to whole body irradiation of 12 Gy or whole abdominal irradiation of up to 20 Gy. We identified a variety of growth and differentiation factors that individually is unable to improve survival of animals exposed to lethal irradiation, but when administered sequentially mitigates radiation injury and improves survival. We termed this phenomenon as synthetic survival and describe a new paradigm whereby the 'synthetic survival' of irradiated tissues can be promoted by systemic administration of growth factors to amplify residual stem cell clonogens post-radiation exposure, followed by a differentiation factor that favors tissue stem cell differentiation. Synthetic survival can be applied to mitigate lethal radiation injury in multiple organs following radiation-induced hematopoeitic, gastrointestinal and pulmonary syndromes. (author)

  13. Novel 5-fluorouracil-resistant human esophageal squamous cell carcinoma cells with dihydropyrimidine dehydrogenase overexpression

    OpenAIRE

    Kikuchi, Osamu; Ohashi, Shinya; Nakai, Yukie; Nakagawa, Shunsaku; Matsuoka, Kazuaki; Kobunai, Takashi; Takechi, Teiji; Amanuma, Yusuke; Yoshioka, Masahiro; Ida, Tomomi; Yamamoto, Yoshihiro; Okuno, Yasushi; Miyamoto, Shin’ichi; Nakagawa, Hiroshi; Matsubara, Kazuo

    2015-01-01

    5-Fluorouracil (5-FU) is a key drug for the treatment of esophageal squamous cell carcinoma (ESCC); however, resistance to it remains a critical limitation to its clinical use. To clarify the mechanisms of 5-FU resistance of ESCC, we originally established 5-FU-resistant ESCC cells, TE-5R, by step-wise treatment with continuously increasing concentrations of 5-FU. The half maximal inhibitory concentration of 5-FU showed that TE-5R cells were 15.6-fold more resistant to 5-FU in comparison with...

  14. A cell-based high-throughput screening assay for radiation susceptibility using automated cell counting

    International Nuclear Information System (INIS)

    Radiotherapy is one of the mainstays in the treatment for cancer, but its success can be limited due to inherent or acquired resistance. Mechanisms underlying radioresistance in various cancers are poorly understood and available radiosensitizers have shown only modest clinical benefit. There is thus a need to identify new targets and drugs for more effective sensitization of cancer cells to irradiation. Compound and RNA interference high-throughput screening technologies allow comprehensive enterprises to identify new agents and targets for radiosensitization. However, the gold standard assay to investigate radiosensitivity of cancer cells in vitro, the colony formation assay (CFA), is unsuitable for high-throughput screening. We developed a new high-throughput screening method for determining radiation susceptibility. Fast and uniform irradiation of batches up to 30 microplates was achieved using a Perspex container and a clinically employed linear accelerator. The readout was done by automated counting of fluorescently stained nuclei using the Acumen eX3 laser scanning cytometer. Assay performance was compared to that of the CFA and the CellTiter-Blue homogeneous uniform-well cell viability assay. The assay was validated in a whole-genome siRNA library screening setting using PC-3 prostate cancer cells. On 4 different cancer cell lines, the automated cell counting assay produced radiation dose response curves that followed a linear-quadratic equation and that exhibited a better correlation to the results of the CFA than did the cell viability assay. Moreover, the cell counting assay could be used to detect radiosensitization by silencing DNA-PKcs or by adding caffeine. In a high-throughput screening setting, using 4 Gy irradiated and control PC-3 cells, the effects of DNA-PKcs siRNA and non-targeting control siRNA could be clearly discriminated. We developed a simple assay for radiation susceptibility that can be used for high-throughput screening. This will aid

  15. 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.

  16. Properties of resistant cells generated from lung cancer cell lines treated with EGFR inhibitors

    International Nuclear Information System (INIS)

    Epidermal growth factor receptor (EGFR) signaling plays an important role in non-small cell lung cancer (NSCLC) and therapeutics targeted against EGFR have been effective in treating a subset of patients bearing somatic EFGR mutations. However, the cancer eventually progresses during treatment with EGFR inhibitors, even in the patients who respond to these drugs initially. Recent studies have identified that the acquisition of resistance in approximately 50% of cases is due to generation of a secondary mutation (T790M) in the EGFR kinase domain. In about 20% of the cases, resistance is associated with the amplification of MET kinase. In the remaining 30-40% of the cases, the mechanism underpinning the therapeutic resistance is unknown. An erlotinib resistant subline (H1650-ER1) was generated upon continuous exposure of NSCLC cell line NCI-H1650 to erlotinib. Cancer stem cell like traits including expression of stem cell markers, enhanced ability to self-renew and differentiate, and increased tumorigenicity in vitro were assessed in erlotinib resistant H1650-ER1 cells. The erlotinib resistant subline contained a population of cells with properties similar to cancer stem cells. These cells were found to be less sensitive towards erlotinib treatment as measured by cell proliferation and generation of tumor spheres in the presence of erlotinib. Our findings suggest that in cases of NSCLC accompanied by mutant EGFR, treatment targeting inhibition of EGFR kinase activity in differentiated cancer cells may generate a population of cancer cells with stem cell properties

  17. Pro-inflammatory agents LPS and IL-6 protect monocytic cell line RAW264.7 from radiation induced cell death

    International Nuclear Information System (INIS)

    Our earlier studies have shown that increased glycolysis protects cells from radiation induced cell death. Pro-inflammatory molecules like LPS have been shown to reduce radiation induced gastro-intestinal syndrome, while IL-6 protects cardiomyocytes from ischemia induced oxidative stress. Interestingly, both pro-inflammatory molecules, LPS and IL-6 induce glycolysis in cells and mimic the high glycolytic phenotype. Therefore, we hypothesize that LPS and IL-6 can protect the hematopoietic cells from radiation induced cell death by inducing glycolysis. To validate our hypothesis, we investigated the response of RAW264.7 cells stimulated with LPS (10 ng/ml) and IL-6 (1 ng/ml), 2 hours prior to irradiation (2 Gy, gamma rays, 60Co). Both LPS and IL-6 protected cells from radiation induced growth inhibition with > 50% increase in cell number as compared to radiation alone. Under these conditions, IL-6 showed more than 2 fold increase in glycolysis, measured by lactate production, which correlated with increased cell number. To understand the mechanisms underlying IL-6 induced radio-resistance, we examined the effects of IL-6 on anti-oxidant defence and mitochondrial status in irradiated cells. Cells treated with IL-6 showed nearly 40% reduced levels of radiation induced delayed reactive oxygen species (ROS), measured at 24 hours after exposure using DCFH2-DA. The decrease in ROS was linked to increased mitochondrial membrane potential (MMP), thereby suggesting that IL-6 induced reduction in ROS levels and high MMP protects the cell from radiation induced cell death. Our results show that both mitochondrial uncouplers and pro-inflammatory molecules (LPS and IL-6) lead to similar metabolic shift in the form of increased glycolysis leading to enhanced radio-resistance. Therefore, we propose that stimulation of glycolysis can be an useful radioprotective strategy, irrespective of the nature of stimulants. Further studies to understand mechanisms underlying IL-6 induced

  18. Mesenchymal stem cell therapy for acute radiation syndrome.

    Science.gov (United States)

    Fukumoto, Risaku

    2016-01-01

    Acute radiation syndrome affects military personnel and civilians following the uncontrolled dispersal of radiation, such as that caused by detonation of nuclear devices and inappropriate medical treatments. Therefore, there is a growing need for medical interventions that facilitate the improved recovery of victims and patients. One promising approach may be cell therapy, which, when appropriately implemented, may facilitate recovery from whole body injuries. This editorial highlights the current knowledge regarding the use of mesenchymal stem cells for the treatment of acute radiation syndrome, the benefits and limitations of which are under investigation. Establishing successful therapies for acute radiation syndrome may require using such a therapeutic approach in addition to conventional approaches. PMID:27182446

  19. Application of radiation for the production of vine resistant to plasmopara

    International Nuclear Information System (INIS)

    The aim of cultivating vine resistant to plasmopara viticola is very important for Portugal as in this country milden is still the most common mycosis of the vine. The polyfactorial character of this resistance which is exhibited by limited infection spots on the leaves, missing 'sources of resistance' in vitis vinifera and correlations between the resistance genes and a few other genes, which cause an inferior quality of grape, justify the interest in the experimental mutagenesis. Thus the cultivation programme which for a long time was carried out according to classical methods (clone cultivation, crossing and mass sowing), now includes the treatment of seedlings and scions with X rays and neutron radiation. In the present report, the results obtained so far regarding the percentage of bud germination and of the chloratic seedlings as well as regarding the cultivation of milden-resistant plants are given. (orig./LH)

  20. Nanodrug Delivery in Reversing Multidrug Resistance in Cancer Cells

    Directory of Open Access Journals (Sweden)

    Sonali eKapse-Mistry

    2014-07-01

    Full Text Available Different mechanisms in cancer cells become resistant to one or more chemotherapeutics is known as multidrug resistance(MDR which hinders chemotherapy efficacy. Potential factors for MDR includes enhanced drug detoxification, decreased drug uptake, increased intracellular nucleophiles levels, enhanced repair of drug induced DNA damage, overexpression of drug transporter such as P-glycoprotein(P-gp, multidrug resistance-associated proteins(MRP1, MRP2 and breast cancer resistance protein(BCRP. Currently nanoassemblies such as polymeric/solid lipid/inorganic/metal nanoparticles, quantum dots, dendrimers, liposomes, micelles has emerged as an innovative, effective and promising platforms for treatment of drug resistant cancer cells. Nanocarriers have potential to improve drug therapeutic index, ability for multifunctionality, divert ABC-transporter mediated drug efflux mechanism and selective targeting to tumor cells, cancer stem cells, tumor initiating cells or cancer microenvironment. Selective nanocarrier targeting to tumor overcomes dose-limiting side effects, lack of selectivity, tissue toxicity, limited drug access to tumor tissues, high drug doses and emergence of multiple drug resistance with conventional or combination chemotherapy. Current review highlights various nanodrug delivery systems to overcome mechanism of MDR by neutralizing, evading or exploiting the drug efflux pumps and those independent of drug efflux pump mechanism by silencing Bcl-2 and HIF1 gene expressions by siRNA and miRNA, modulating ceramide levels and targeting NF-B. Theragnostics combining a cytotoxic agent, targeting moiety, chemosensitizing agent and diagnostic imaging aid are highlighted as effective and innovative systems for tumor localization and overcoming MDR. Physical approaches such as combination of drug with thermal/ultrasound/photodynamic therapies to overcome MDR are focused. The review focuses on newer drug delivery systems developed to overcome

  1. Development of ultrasonic transducer with high resistance to temperature and radiation

    International Nuclear Information System (INIS)

    Ordinary ultrasonic transducers cannot be used to inspect equipment at a high radiation facility such as vitrification facility or fusion reactor. IHI has developed an ultrasonic transducer with high resistance to temperature and radiation and confirmed the radiation tolerance up to 10 MGy. IHI has applied the ultrasonic transducer to lid welding inspection of vitrification packages, and obtained good results such as clear detection of an artificial 0.5 mm diameter hole penetrating the stainless steel lid welding. This technology could be applied to ISI (In-Service Inspection) of nuclear plants, ensuring safe operation of nuclear plants. (author)

  2. Cancer stem cells and resistance to chemo and radio therapy.

    Science.gov (United States)

    Malik, Babar; Nie, Daotai

    2012-01-01

    Cancer stem cells (CSCs, or tumor initiating cells) are responsible for tumor initiation. If cancer treatment kills most of cancer cells in the stage of transit amplifying and differentiation without killing the stem cells, the surviving CSCs will eventually lead to recurrence of tumors. Studies have suggested that CSCs may be the primary mediators of resistance to chemo- and radio-therapy, leading to failure in cancer therapy. Numerous targets are being investigated for their potential involvement in the self-renewal and chemo- and radio-resistance of cancer cells. However, despite the intensive efforts invested into characterizing the role of cancer stem cells, there is a sense of uncertainty regarding the identity and number of these cells as well as the implications in cancer treatment. In this review, we will discuss the identification of CSCs by cell surface markers, the biology of CSCs, and the role of CSCs in resistance to radio- and chemo-therapy. This review will discuss the advances in targeting CSCs to improve the efficacy of chemo- and radio-therapy. PMID:22202026

  3. Radiation-resistance of micro-organisms from air in clean premises

    International Nuclear Information System (INIS)

    A total of more than 20.000 colonies of bacteria and fungi collected by means of slit-sampler in controlled environments for aseptic microbiological work were included in a screening test of the occurence of micro-organisms with high radiation-resistance. A D-6 value, the dose necessary to reduce the initial population of micro-organisms with a factor of one million, of 1.8 megarads or more, was used as criterion. A total of 117 strains were isolated. No differences in the proportion of radiation-resistant strains could be demonstrated between different laboratories or at various seasons of the year. In the lower half of the resistance spectrum for the 117 isolates with unusually high radiation-resistance, half of the strains were spore-forming. In the uppermost part of the spectrum, spores were not observed. Rods dominated the lower part of the resistance spectrum, cocci the upper part. A large proportion of the strains were pigment-producing. 50 strains with D-6 values of 3.2 megarads or higher, and 15 strains with D-6 values of 4.5 megarads or higher, were found. In the upper part of the resistance spectrum the dose-response curves for the organisms were all upward convex, when the organisms were irradiated in a dry state and glued together with small amounts of organic compounds. On the basis of the proportion of radiation-resistant bacteria demonstrated and the assumptions that a medical device with an average total count of 20 contaminating organisms per product unit prior to irradiation should comply with an established norm (1:106), or a suggested norm (1:103), respectively, for radiation sterilized devices, the minimum dose necessary for routine sterilization was estimated as about 3.8 megarads and about 2.0 megarads. In parallel screening tests for heat-resistant organisms, only one resistant, thermophilic strain was found among organisms equivalent to about 7.000 colony-forming units as total counts on slit-sampler plates, and no resistant mesophilic

  4. Epidermal stem cells response to radiative genotoxic stress

    International Nuclear Information System (INIS)

    Human skin is the first organ exposed to various environmental stresses, which requires the development by skin stem cells of specific mechanisms to protect themselves and to ensure tissue homeostasis. As stem cells are responsible for the maintenance of epidermis during individual lifetime, the preservation of genomic integrity in these cells is essential. My PhD aimed at exploring the mechanisms set up by epidermal stem cells in order to protect themselves from two genotoxic stresses, ionizing radiation (Gamma Rays) and ultraviolet radiation (UVB). To begin my PhD, I have taken part of the demonstration of protective mechanisms used by keratinocyte stem cells after ionizing radiation. It has been shown that these cells are able to rapidly repair most types of radiation-induced DNA damage. Furthermore, we demonstrated that this repair is activated by the fibroblast growth factor 2 (FGF2). In order to know if this protective mechanism is also operating in cutaneous carcinoma stem cells, we investigated the response to gamma Rays of carcinoma stem cells isolated from a human carcinoma cell line. As in normal keratinocyte stem cells, we demonstrated that cancer stem cells could rapidly repair radio-induced DNA damage. Furthermore, fibroblast growth factor 2 also mediates this repair, notably thanks to its nuclear isoforms. The second project of my PhD was to study human epidermal stem cells and progenitors responses to UVB radiation. Once cytometry and irradiation conditions were set up, the toxicity of UVB radiation has been evaluate in the primary cell model. We then characterized UVB photons effects on cell viability, proliferation and repair of DNA damage. This study allowed us to bring out that responses of stem cells and their progeny to UVB are different, notably at the level of part of their repair activity of DNA damage. Moreover, progenitors and stem cells transcriptomic responses after UVB irradiation have been study in order to analyze the global

  5. Radiation resistance and thermal creep of ODS ferritic steels

    International Nuclear Information System (INIS)

    Oxide dispersion strengthened (ODS) ferritic steels containing 0.38-0.39 wt% Y2O3 have been produced by mechanical alloying. After thermo-mechanical treatment, the structure of ODS steels includes polygonized extended grains and a great number (to ∼1016-1017 cm-3) of ultrafine complex yttrium oxides ∼2-3 nm in diameter. Irradiation by fast neutrons to 4.5x1026 n/m2 (340 K) and 1.5x1022 n/m2 (77 K) leads to strengthening and plasticity decreasing in ODS alloys. The advantages of ODS ferritic steels in creep resistance and strength against ferritic-martensitic steel 12Cr-2Mo-Nb-B-V and austenitic steel 16Cr-15Ni-3Mo-Ti-V display obviously when creep rate is approximately 10-2 h-1 and fracture time is longer than 1000 h

  6. Radiation induced frequency and resistance changes in electrolyzed high purity quartz resonators

    International Nuclear Information System (INIS)

    Radiation induced frequency and resistance changes in precision 5 MHz AT-cut quartz resonators fabricated from electrolyzed, high purity quarts are described. A description is given of the radiation measurement methods, transient and steady-state data, and the results of thermal modeling. It is concluded that SARP optical and Premium-Q quartz may be pure enough as grown that (1) the usual frequency time dependent recovery characteristic of t/sup -1/2/ is not observed; (2) without electrolysis, the impurity levels are nevertheless high enough to cause a significant decrease in Q for a short time following a pulse of ionizing radiation; (3) electrolysis can further reduce radiation response so that impurity effects are no longer significant; and (4) the transient radiation response in electrolyzed quartz is primarily thermal in nature

  7. Identifying the Proteins that Mediate the Ionizing Radiation Resistance of Deinococcus Radiodurans R1

    Energy Technology Data Exchange (ETDEWEB)

    Battista, John R

    2010-02-22

    The primary objectives of this proposal was to define the subset of proteins required for the ionizing radiation (IR) resistance of Deinococcus radiodurans R1, characterize the activities of those proteins, and apply what was learned to problems of interest to the Department of Energy.

  8. RADIATION-RESISTANT FIBER OPTIC STRAIN SENSORS FOR SNS TARGET INSTRUMENTATION

    Energy Technology Data Exchange (ETDEWEB)

    Blokland, Willem [ORNL; Bryan, Jeff [ORNL; Riemer, Bernie [ORNL; Sangrey, Robert L [ORNL; Wendel, Mark W [ORNL; Liu, Yun [ORNL

    2016-01-01

    Measurement of stresses and strains in the mercury tar-get vessel of the Spallation Neutron Source (SNS) is important to understand the structural dynamics of the target. This work reports the development of radiation-resistant fiber optic strain sensors for the SNS target in-strumentation.

  9. Effect that radiation exerts to insulation breakdown of heat resistant polymer materials

    International Nuclear Information System (INIS)

    Artificial satellites are always exposed to cosmic rays which contain the radiations which do not reach the ground, therefore, the radiation resistance of the polymer insulators for cables and others used in such environment becomes a problem. Also the polymer insulator materials used for nuclear facilities require excellent radiation resistance. It is important to examine the effect that radiation exerts to electric insulation characteristics from the viewpoint of material development. In this paper, the insulation breakdown characteristics of heat resistant polymer films and the mini-cables made for trial of heat resistant polymer materials in the case without irradiation and in the case of gamma ray irradiation, and the results of the structural analysis are reported. The specimens tested, the experimental method and the results are described. The insulation breakdown strength of PFA and FEP films lowered from 0.15-0.2 MGy, but that of PEEK film did not change up to 5 MGy. It was found that fluorine group resins were apt to deteriorate by oxidation as dose increased. (K.I.)

  10. Radiation resistance of polymer materials. Degradation evaluation by accelerated testing for application condition

    International Nuclear Information System (INIS)

    This paper presents re-evaluated radiation resistance property data of polymer materials, which had been tested in past times in TAKASAKI Quantum Beam Science Directorate, for the future study of ageing evaluation of low voltage electric cable insulation materials used in light-water nuclear reactors. The radiation resistance of 25 types of plastics and rubbers materials applied in practical environments was evaluated by the accelerated testing of gamma-ray irradiation under oxygen pressure, and was compared with the radiation resistance determined from the traditional testing by irradiation with a high dose rate in air. The polymer materials were formulated to be similar or equivalent to practical materials, and the most of formulation (chemical compounds and quantities) were described. For all materials, the tensile properties (elongation at break, ultimate strength, 100% or 200% modulus), electric resistivity, gel-fraction, and density were measured after irradiation in oxidation conditions and irradiation in air with a high dose rate (non-oxidation conditions). The data of relations between each properties and total dose at various conditions were compiled, and the relations among the changes of mechanical properties, electrical properties, and radiation induced chemical reactions were discussed. (author)

  11. On possibility to make a new type of calorimeter: radiation resistant and fast

    International Nuclear Information System (INIS)

    It is proposed to use electron multipliers, which directly detect low energy shower particles as an active element in sandwich calorimeters. The approach pffers fast and radiation resistant calorimetry. Test of the method is presented with the use of a microchannel plate. 4 refs.; 4 figs

  12. Subcurative radiation significantly increases cell proliferation, invasion, and migration of primary glioblastoma multiforme in vivo

    Institute of Scientific and Technical Information of China (English)

    Adarsh Shankar; Robert A. Knight; Stephen Brown; Ali S. Arbab; Sanath Kumar; Asm Iskander; Nadimpalli RS Varma; Branislava Janic; Ana deCarvalho; Tom Mikkelsen; Joseph A. Frank; Meser M. Ali

    2014-01-01

    Tumor cellproliferation, infiltration, migration, and neovascularization are known causes of treatment resistance in glioblastoma multiforme (GBM). The purpose of this study was to determine the effect of radiation on the growth characteristics of primary human GBM developed in a nude rat. Primary GBM cells grown from explanted GBM tissues were implanted orthotopically in nude rats. Tumor growth was confirmed by magnetic resonance imaging on day 77 (baseline) after implantation. The rats underwent irradiation to a dose of 50 Gy delivered subcuratively on day 84 postimplantation (n= 8), or underwent no radiation (n= 8). Brain tissues were obtained on day 112 (nonirradiated) or day 133 (irradiated). Immunohistochemistry was performed to determine tumor cell proliferation (Ki-67) and to assess the expression of infiltration marker (matrix metalloproteinase-2, MMP-2) and cell migration marker (CD44). Tumor neovascularization was assessed by microvessel density using von-Willebrand factor (vWF) staining. Magnetic resonance imaging showed well-developed, infiltrative tumors in 11 weeks postimplantation. The proportion of Ki-67-positive cells in tumors undergoing radiation was (71 ± 15)%compared with (25 ± 12)%in the nonirradiated group (P=0.02). The number of MMP-2-positive areas and proportion of CD44-positive cells were also high in tumors receiving radiation, indicating great invasion and infiltration. Microvessel density analysis did not show a significant difference between nonirradiated and irradiated tumors. Taken together, we found that subcurative radiation significantly increased proliferation, invasion, and migration of primary GBM. Our study provides insights into possible mechanisms of treatment resistance fol owing radiation therapy for GBM.

  13. Radiation damage in negative-differential resistance devices

    International Nuclear Information System (INIS)

    Tunnel diodes made with silicon and gallium arsenide have been tested in both neutron- and gamma-radiation environments. Experimental data show that failure usually occurs in the range 1014-1018 n cm-2 or 50-270 Mrad range. The primary failure mechanism for neutron irradiated samples is an increase in the valley current (from 0.10 mA to 0.58 mA and from 1.5 μA to 30 μA for silicon and GaAs diodes, respectively). In the case of gamma-irradiated silicon samples, the valley current reaches a value of 0.48 mA, at 260.8 Mrad, although their initial values are 0.1 mA. As a result, the peak-to-valley current ratios of the irradiated devices were shown to decrease severely. Both the valley and forward peak voltage values were shown to decrease with radiation. Values of 0.18 and 0.25 V for silicon samples were measured after exposure to 5 x 1016 n cm-2 although their initial values were 0.42 and 0.80 V, respectively. As a result, the devices' output power were shown to be affected seriously. Finally, silicon devices irradiated for 48 h in the ET-RR-1 research reactor, Egypt, for up to 1.872 x 1018 n cm-2 or to gamma doses up to 2.6 x 108 rad, were greatly influenced and they lost their main feature as PN-junctions. (Author)

  14. Overcoming tumour radiation resistance resulting from acute hypoxia

    International Nuclear Information System (INIS)

    Radioresistant hypoxic cells in tumours are believed to compromise the success of clinical radiotherapy. This brief article discusses three methods of overcoming acute hypoxia in tumours, all of which are applicable in clinical radiotherapy. Of these nicotinamide probably has the greatest clinical potential. (UK)

  15. 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

  16. Preclinical screening for drugs effective against 5-fluorouracil-resistant cells with a murine L5178Y cell line in vitro

    International Nuclear Information System (INIS)

    A subline of L5178Y cells has been established in vitro that exhibits a fiftyfold order of resistance to 5-fluorouracil (FUra) as compared to that of the parent line. The cytotoxic effects of 24-hour exposures to 23 antitumor drugs and to radiation were compared in the two cell lines. Four patterns of response were identified: 1) Only two drugs, mitomycin C and adriamycin, proved significantly more cytotoxic to FUra-resistant cells. 2) Four other drugs--anguidine, 4'-(9-acridinylamino)-methanesulfon-m-anisidide, melphalan, and quelamycin--showed marginal superiority against resistant cells. 3) X-radiation and the majority of drugs tested--including 5-azacytidine, 1,3-bis(2-chloroethyl)-1-nitrosourea, cisplatin, bleomycin, dibromodulcitol, razoxane, hydroxyurea, methotrexate, teniposide, etoposide, and three experimental agents, metoprine, spirogermanium HCl, and ellipticinum--proved equally cytotoxic to both cell lines. 4) Cross-resistance with FUra was exhibited with vincristine, vindesine, pyrazofurin, and indicine-N-oxide. This experimental system provides a simple method of testing agents for activity against FUra-resistant cells before phase 1 clinical studies

  17. Radiation resistance of lactobacilli isolated from radurized meat relative to growth and environment

    International Nuclear Information System (INIS)

    Of 113 lactobacilli isolated from radurized (5 kGy) minced meat, 7 Lactobacillus sake strains, 1 L. curvatus strain, and 1 L. farciminis strain were used for radiation resistance studies in a semisynthetic substrate (i.e., modified MRS broth). Five reference Lactobacillus spp. one Staphylococcus aureus strain, and one Salmonella typhimurium strain were used for comparative purposes. All L. sake isolates exhibited the phenomenon of being more resistant to gamma-irradiation in the exponential (log) phase than in the stationary phase of their growth cycles by a factor of 28%. Four reference strains also exhibited this phenomenon, with L. sake (DSM 20017) showing a 68% increase in resistance in the log phase over the stationary phase. This phenomenon was not common to all bacteria tested and is not common to all strains with high radiation resistance. Four L. sake isolates and three reference strains were used in radiation sensitivity testing in a natural food system (i.e., meat). The bacteria were irradiated in minced meat and packaged under four different conditions (air, vacuum, CO2, and N2). Organisms exhibited the highest death rate (lowest D10 values [doses required to reduce the logarithm of the bacterial population by 1] under CO2 packaging conditions, but resistance to irradiation was increased under N2. The D10 values of the isolates were generally greater than those of the reference strains. The D10 values were also higher (approximately two times) in meat than in a semisynthetic growth medium

  18. Depression of p53-independent Akt survival signals after high-LET radiation in mutated p53 cells

    Science.gov (United States)

    Ohnishi, Takeo; Takahashi, Akihisa; Nakagawa, Yosuke

    Although mutations and deletions in the p53 tumor suppressor gene lead to resistance to low linear energy transfer (LET) radiation, high-LET radiation efficiently induces cell lethality and apoptosis regardless of the p53 gene status. Recently, it has been suggested that the induction of p53-independent apoptosis takes place through the activation of Caspase-9 which results in the cleavage of Caspase-3 and poly (ADP-ribose) polymerase (PARP). This study was designed to examine if high-LET radiation depresses the activities of serine/threonine protein kinase B (PKB, also known as Akt) and Akt-related proteins. Human gingival cancer cells (Ca9-22 cells) harboring a mutated p53 (mp53) gene were irradiated with 2 Gy of X-rays or Fe-ion beams. The cellular contents of Akt-related proteins participating in cell survival signals were analyzed with Western blotting analysis 1 h, 2 h, 3 h and 6 h after irradiation. Cell cycle distributions after irradiation were assayed with flow cytometric analysis.Akt-related protein levels were decreased when cells were irradiated with high-LET radiation. High-LET radiation increased G _{2}/M phase arrests and suppressed the progression of the cell cycle much more efficiently when compared to low-LET radiation. These results suggest that high-LET radiation enhances apoptosis through the activation of Caspase-3 and Caspase-9, and depresses cell growth by suppressing Akt-related signals, even in the mp53 cells.

  19. 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)

  20. Development of EPDM based thermoplastic elastomers for oil resistant applications: optimization of radiation grafting parameters

    International Nuclear Information System (INIS)

    Full text: Ethylene-propylene diene terpolymer (EPDM) is currently among the most industrially useful elastomers because of its certain unique properties like excellent heat resistance, resistance towards ozone deterioration, high impact strength. However EPDM has a serious drawback of weak adhesion properties and tendency to swell in contact with paraffin oil and aromatic hydrocarbons. Blending EPDM with suitable polar elastomers or grafting polar polymer chains onto EPDM is an easy method to overcome this drawback. Radiation grafting of Acrylonitrile (ACN) on EPDM provides an easy and effective method of incorporating ACN uniformly on the EPDM backbone. Grafting of ACN on EPDM is expected to result grafted copolymer with better oil resistance, hardness and better compatibility with polar polymer matrices. In the present study radiation induced grafting of ACN onto EPDM rubber film was investigated by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, types of solvents and monomer content on extent of grafting was studied. The solvent composition of Acetone:CCl4 (20:80) was found to be the optimum mixture which resulted in highest degree of grafting. It was found that the degree of grafting increases with radiation dose, monomer content and decreases with dose rate

  1. 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.

  2. 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...

  3. A magnetic vehicle realized tumor cell-targeted radiotherapy using low-dose radiation.

    Science.gov (United States)

    Chen, Hsiao-Ping; Tung, Fu-I; Chen, Ming-Hong; Liu, Tse-Ying

    2016-03-28

    Radiotherapy, a common cancer treatment, often adversely affects the surrounding healthy tissue and/or cells. Some tumor tissue-focused radiation therapies have been developed to lower radiation-induced lesion formation; however, achieving tumor cell-targeted radiotherapy (i.e., precisely focusing the radiation efficacy to tumor cells) remains a challenge. In the present study, we developed a novel tumor cell-targeted radiotherapy, named targeted sensitization-enhanced radiotherapy (TSER), that exploits tumor-specific folic acid-conjugated carboxymethyl lauryl chitosan/superparamagnetic iron oxide (FA-CLC/SPIO) micelles to effectively deliver chlorin e6 (Ce6, a sonosensitizer) to mitochondria of HeLa cells under magnetic guidance. For the in vitro tests, the sensitization of Ce6 induced by ultrasound, that could weaken the radiation resistant ability of tumor cells, occurred only in Ce6-internalizing tumor cells. Therefore, low-dose X-ray irradiation, that was not harmful to normal cells, could exert high tumor cell-specific killing ability. The ratio of viable normal cells to tumor cells was increased considerably, from 7.8 (at 24h) to 97.1 (at 72h), after they had received TSER treatment. Our data suggest that TSER treatment significantly weakens tumor cells, resulting in decreased viability in vitro as well as decreased in vivo subcutaneous tumor growth in nude mice, while the adverse effects were minimal. Taken together, TSER treatment appears to be an effective, clinically feasible tumor cell-targeted radiotherapy that can solve the problems of traditional radiotherapy and photodynamic therapy. PMID:26892750

  4. Radiation induced mitochondrial biogenesis: limitations of metabolic viability based assays in measuring radiation induced cell death

    International Nuclear Information System (INIS)

    Many techniques based on metabolic viability of cells employing MTT and MTS assay are being widely used to measure the radiation and chemotherapeutics induced cell death, because of their high throughput capability. These assays are based on mitochondrial potential of cells to convert the substrate in to measurable products and remain dependent on this notion that all the cells untreated and treated will have equal mitochondrial content and metabolic potential. However, it is increasingly becoming clear that treatment induced changes in both mitochondrial content and metabolism can influence the metabolic viability of cells and radiation is a potential mitochondrial biogenesis inducer. Therefore, we tested if metabolic viability based assays are true measure of radiation induced cell death using the widely used cell lines like RAW264.7, HEK293, NIH3T3, J774.1, BMG-1, MDAMB231, MCF-7, A549 and HeLa. Cells were irradiated with gamma rays (60Co) and enumerated cell numbers (by hemocytometer) and metabolic viability using MTT assay at 24 and 48 hours after exposure. At all the absorbed doses (0-5 Gy), the extent of reduction in cell number was found to be larger than the decrease in formazan formation in all the cell lines tested. Further, this difference in the cell number and formazan formation varied significantly among the cell lines. To test if the increased formazan formation is due to increased mitochondrial content per cell, we analyzed the radiation induced mitochondrial biogenesis using mitochondria specific dye mitotracker red and found a 1.5 to 2 fold increase in mitochondrial content. These findings suggest that radiation induces mitochondrial biogenesis that enhances the metabolic potential leading to increased formazan formation. Therefore, conclusions drawn on radiation induced cytotoxicity based on metabolic viability assays are likely to be erroneous as it may not correlate with growth inhibition and/or loss of clonogenic survival. (author)

  5. Response of sensitive human ataxia and resistant T-1 cell lines to accelerated heavy ions

    International Nuclear Information System (INIS)

    The radiation dose responses of fibroblast from a patient with Ataxia telangiectasis (AT-2SF) and an established line of human T-1 cells were studied. Nearly monoenergetic accelerated neon and argon ions were used at the Berkeley Bevalac with various residual range values. The LET of the particles varied from 30 keV/μm to over 1000 keV/μm. All Ataxia survival curves were exponential functions of the dose. Their radiosensitivity reached peak values at 100 to 200 keV/μm. Human T-1 cells have effective sublethal damage repair as has been evidenced by split dose experiments, and they are much more resistant to low LET than to high LET radiation. The repair-misrepair model has been used to interpret these results. We have obtained mathematical expressions that describe the cross sections and inactivation coefficients for both human cell lines as a function of the LET and the type of particle used. The results suggest either that high-LET particles induce a greater number of radiolesions per track or that heavy-ions at high LET induce lesions that kill cells more effectively and that are different from those produced at low LET. We assume that the lesions induced in T-1 and Ataxia cells are qualitatively similar and that each cell line attempts to repair these lesions. The result in most irradiated Ataxia cells, however, is either lethal misrepair or incomplete repair leading to cell death. 63 references, 10 figures, 1 table

  6. 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)

  7. Radiation-induced cerebral cell apoptosis in rats

    International Nuclear Information System (INIS)

    Objective: To study the influence of radiation on rat cerebral cells including neurons and gliocytes. Methods: The rats were divided into control group and X-ray radiation groups with different doses. The apoptosis of cells at different time points after radiation was observed by optic microscopy, electron microscopy and DNA agarose gel electrophoresis. The double label method (in situ end-labeling of DNA strand breaks for labeling apoptotic cells, and immunohistochemistry for labeling cell type) was used to label apoptotic neurons and gliocytes cells separately. Results: The distinct morphological features of apoptosis and the DNA fragmentation ladders on agarose gel electrophoresis were seen in radiation groups. The rate of apoptosis in the adult rat brain was low. There were many apoptotic glial cells (about 93%) and a few apoptotic neurons (about 5%) after radiation. The apoptotic rate in high dose group was higher than that in low dose group. Conclusion: Apoptosis can be induced by radiation in rat brain, the apoptotic rate increases with a increasing dose in the range of 2-8 Gy. The gliocytes are more sensitive to radiation-induced apoptosis than the neurons

  8. Response of multiple myeloma cells and its cancer stem cell to X rays and carbon ion radiations

    International Nuclear Information System (INIS)

    The full text of the publication follows. Study of the DNA damage response (DDR) is essential to improve the treatment of cancer, as most of current therapies are targeting DDR pathway. Interestingly, DDR has been shown to be over-activated in cancer stem cells (CSC), contributing herein to the resistance of the overall tumor towards radiation. The CSC from multiple myeloma (MM), a haematological malignancy, has been isolated [1]. MM is particularly resistant to treatments inducing DNA damages. This suggests that the DDR is altered in these cells and might be one of the causes of tumorigenesis. However, DDR of MM remains poorly studied. We undertook the study of the DDR after X rays and carbon ions radiations, more energetic, in cell lines, CSC and clinical specimens of MM. Our preliminary results obtained in MM cell lines suggest that radiation-induced DNA damages lead to an over-activation of the cell cycle checkpoint proteins in MM cells, which remain consequently blocked in G2/M of the cell cycle. This contributes to MM radioresistance and the underlying molecular mechanisms are being investigated. Besides, based on the activity of ALDH, we confirm that in the MM cancer cells population exists a subpopulation, which displays stem cell properties. This subpopulation of CSC was isolated based on the expression of the surface marker CD138 as previously described [2]. We confirmed that CD138- cells are mostly quiescent cells, while cells CD138+ are cycling. Furthermore, CD138- cells are able to clone in vitro more efficiently than CD138+ cells. This shows unambiguously that MM CD138- cells possess stem cell properties. The response of the CSC, CD138+, to radiations are currently being investigated. With this study, we hope to gain further understanding on the DNA damage response in MM and thereby design new therapeutic strategies. References: [1] Matsui et al, Blood. 2004 Mar 15;103(6):2332-6; [2] Matsui et al, Cancer Res. 2008 Jan 1; 68(1):190-7. (authors)

  9. Basal DNA repair machinery is subject to positive selection in ionizing-radiation-resistant bacteria

    International Nuclear Information System (INIS)

    In this work, we used the programs MultiParanoid and DnaSP to deduce the sets of orthologs that potentially evolved due to positive Darwinian selection in ionizing-radiation-resistant bacteria (IRRB ; Deinococcus geothermalis, Deinococcus radiodurans, Kineococcus radiotolerans, and Rubrobacter xylanophilus). We find that positive selection targets 689 ortholog sets of IRRB. Among these, 58 ortholog sets are absent in ionizing-radiation-sensitive bacteria (IRSB: Escherichia coli and Thermus thermophilus). The most striking finding is that all basal DNA repair genes in IRRB, unlike many of their orthologs in IRSB, are subject to positive selection. Our results provide the first in silico prediction of positively selected genes with potential roles in the molecular basis of resistance to gamma radiation and tolerance of desiccation in IRRB. Identification of these genes provides a basis for future experimental work aimed at understanding the metabolic networks in which they participate

  10. Atomic simulations of Fe/Ni multilayer nanocomposites on the radiation damage resistance

    Science.gov (United States)

    Chen, Feida; Tang, Xiaobin; Yang, Yahui; Huang, Hai; Liu, Jian; Li, Huan; Chen, Da

    2016-01-01

    We investigated the radiation damage resistance of the Fe/Ni multilayer nanocomposites by molecular dynamics. In the paper, two types of interface configuration with different orientation relationship were constructed. Their morphology evolution and number of final surviving defects induced by cascade collisions were discussed respectively. The interfaces of the two types of Fe/Ni multilayers kept distinct during the long-time relaxation before cascade. The comparison of surviving defects number produced by PKA with 5 keV at 100 K showed that the Fe/Ni multilayers have greater radiation tolerance than that of the bulk materials. However, the orientation relationship of the interface influences the defects self-healing capability greatly when the multilayers are irradiated by higher energy PKA or at high temperature. The radiation damage resistance of the Nishiyama - Wassermann type Fe/Ni multilayers which have larger lattice misfit is more stable than that of the Kurdjumov - Sachs type.

  11. SIRT2 regulates insulin sensitivity in insulin resistant neuronal cells.

    Science.gov (United States)

    Arora, Amita; Dey, Chinmoy Sankar

    2016-06-10

    Insulin resistance in brain is well-associated with pathophysiology of deficits in whole-body energy metabolism, neurodegenerative diseases etc. Among the seven sirtuins, SIRT2 is the major deacetylase expressed in brain. Inhibition of SIRT2 confers neuroprotection in case of Parkinson's disease (PD) and Huntington's disease (HD). However, the role of this sirtuin in neuronal insulin resistance is not known. In this study, we report the role of SIRT2 in regulating insulin-sensitivity in neuronal cells in vitro. Using approaches like pharmacological inhibition of SIRT2, siRNA mediated SIRT2 knockdown and over-expression of wild-type and catalytically-mutated SIRT2, we observed that downregulation of SIRT2 ameliorated the reduced activity of AKT and increased insulin-stimulated glucose uptake in insulin resistant neuro-2a cells. The data was supported by over expression of catalytically-inactive SIRT2 in insulin-resistant human SH-SY5Y neuronal cells. Data highlights a crucial role of SIRT2 in regulation of neuronal insulin sensitivity under insulin resistant condition. PMID:27163642

  12. Deinococcus mumbaiensis sp. nov., a radiation-resistant pleomorphic bacterium isolated from Mumbai, India.

    Science.gov (United States)

    Shashidhar, Ravindranath; Bandekar, Jayant R

    2006-01-01

    A radiation-resistant, Gram-negative and pleomorphic bacterium (CON-1) was isolated from a contaminated tryptone glucose yeast extract agar plate in the laboratory. It was red pigmented, nonmotile, nonsporulating, and aerobic, and contained MK-8 as respiratory quinone. The cell wall of this bacterium contained ornithine. The major fatty acids were C16:0, C16:1, C17:0, C18:1 and iso C18:0. The DNA of CON-1 had a G+C content of 70 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that CON-1 exhibited a maximum similarity (94.72%) with Deinococcus grandis. Based on the genotypic, phenotypic and chemotaxonomic characteristics, the bacterium CON-1 was identified as a new species of the genus Deinococcus, for which the name Deinococcus mumbaiensis sp. nov. is proposed. The type strain of D. mumbaiensis is CON-1 (MTCC 7297(T)=DSM 17424(T)). PMID:16445756

  13. Development of disease preventive method using radiated pathogenic microorganisms, cell lines and animals

    International Nuclear Information System (INIS)

    The effects of radiation were investigated on pathogenic plasmid aiming at a development of a method to induce mutagenesis in plasmid DNA by radiation. To construct an experimental system which allows to detect a plasmid-segregated cell, kanamycin-resistant casette was inserted into pX02, a capsule plasmid in Bacillus anthracis to produce acpA:: Kmr by homologous recombination. This plasmid is thought available for analyzing the rate of plasmid segregation caused by radiation. Next, developments of detection and determination methods for various cytokines were attempted by RT-PCR method with an aim to investigate the expression changes of cytokine mRNA in calf immunocytes by radiation. In calf peripheral monocytes and alveolar macrophages, expressions of cytokine mRNAs such as IL-4, IFNα and GM-CSF mRNA as well as IL-1α, IL-1β, IL-2 and IL-6 were detected by RT-PCR method. (M.N.)

  14. Development of simplified process for environmentally resistant cells. Final report

    Energy Technology Data Exchange (ETDEWEB)

    King, W.J.

    1980-12-01

    A program to develop a simple, foolproof, all-vacuum solar cell manufacturing process which can be completely automated and which results in medium efficiency cells which are inherently environmentally resistant is described. All components of the completed cells are integrated into a monolithic structure with no material interfaces. The exposed materials (Si, Al/sub 2/O/sub 3/, Al, Ni) are all resistant to atmospheric attack and the junction, per se, is passivated to prevent long term degradation. Such cells are intended to be incorporated into a simple module consisting basically of a press-formed metallic superstructure with a separated glass cover for missile, etc., protection. A 5 cm x 5 cm test cell configuration was designed in which the various efficiency loss factors were adjusted to yield a 10% AMI cell. Each of the cell elements was individually optimized for combination with the others. The basic cell consists of alloyed front (Al) and back (Ag plus Ni) contacts, a multi-purpose (AR, hermetic seal, implantation oxide) front surface coating of Al/sub 2/O/sub 3/, and an implanted front junction. Implantation damage annealing and contact alloying are carried out in a simple one step thermal treatment at 870/sup 0/C using a resistance heated furnace in vacuum. The use of non-analyzed and semi-analyzed beams for fabricating these cells was developed by KCI. A final lot of 50 cells made using the semi-analyzed beam method had an average efficiency of 10.4% at AMI (28 +- 1/sup 0/C). An economic analysis predicts a manufacturing cost of $.45/peak-watt for these cells using a one machine automatic method.

  15. High temperature creep strength of Advanced Radiation Resistant Oxide Dispersion Strengthened Steels

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Sanghoon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    Austenitic stainless steel may be one of the candidates because of good strength and corrosion resistance at the high temperatures, however irradiation swelling well occurred to 120dpa at high temperatures and this leads the decrease of the mechanical properties and dimensional stability. Compared to this, ferritic/martensitic steel is a good solution because of excellent thermal conductivity and good swelling resistance. Unfortunately, the available temperature range of ferritic/martensitic steel is limited up to 650 .deg. C. ODS steel is the most promising structural material because of excellent creep and irradiation resistance by uniformly distributed nano-oxide particles with a high density which is extremely stable at the high temperature in ferritic/martensitic matrix. In this study, high temperature strength of advanced radiation resistance ODS steel was investigated for the core structural material of next generation nuclear systems. ODS martensitic steel was designed to have high homogeneity, productivity and reproducibility. Mechanical alloying, hot isostactic pressing and hot rolling processes were employed to fabricate the ODS steels, and creep rupture test as well as tensile test were examined to investigate the behavior at high temperatures. ODS steels were fabricated by a mechanical alloying and hot consolidation processes. Mechanical properties at high temperatures were investigated. The creep resistance of advanced radiation resistant ODS steels was more superior than those of ferritic/ martensitic steel, austenitic stainless steel and even a conventional ODS steel.

  16. High temperature creep strength of Advanced Radiation Resistant Oxide Dispersion Strengthened Steels

    International Nuclear Information System (INIS)

    Austenitic stainless steel may be one of the candidates because of good strength and corrosion resistance at the high temperatures, however irradiation swelling well occurred to 120dpa at high temperatures and this leads the decrease of the mechanical properties and dimensional stability. Compared to this, ferritic/martensitic steel is a good solution because of excellent thermal conductivity and good swelling resistance. Unfortunately, the available temperature range of ferritic/martensitic steel is limited up to 650 .deg. C. ODS steel is the most promising structural material because of excellent creep and irradiation resistance by uniformly distributed nano-oxide particles with a high density which is extremely stable at the high temperature in ferritic/martensitic matrix. In this study, high temperature strength of advanced radiation resistance ODS steel was investigated for the core structural material of next generation nuclear systems. ODS martensitic steel was designed to have high homogeneity, productivity and reproducibility. Mechanical alloying, hot isostactic pressing and hot rolling processes were employed to fabricate the ODS steels, and creep rupture test as well as tensile test were examined to investigate the behavior at high temperatures. ODS steels were fabricated by a mechanical alloying and hot consolidation processes. Mechanical properties at high temperatures were investigated. The creep resistance of advanced radiation resistant ODS steels was more superior than those of ferritic/ martensitic steel, austenitic stainless steel and even a conventional ODS steel

  17. Binding and uptake of diphtheria toxin by toxin-resistant Chinese hamster ovary and mouse cells.

    OpenAIRE

    Didsbury, J R; Moehring, J M; Moehring, T. J.

    1983-01-01

    We investigated two phenotypically distinct types of diphtheria toxin-resistant mutants of Chinese hamster cells and compared their resistance with that of naturally resistant mouse cells. All are resistant due to a defect in the process of internalization and delivery of toxin to its target in the cytosol, elongation factor 2. By cell hybridization studies, analysis of cross-resistance, and determination of specific binding sites for 125I-labeled diphtheria toxin, we showed that these cell s...

  18. Slow-Cycling Therapy-Resistant Cancer Cells

    OpenAIRE

    Moore, Nathan; Houghton, JeanMarie; Lyle, Stephen

    2011-01-01

    Tumor recurrence after chemotherapy is a major cause of patient morbidity and mortality. Recurrences are thought to be secondary to small subsets of cancer cells that are better able to survive traditional forms of chemotherapy and thus drive tumor regrowth. The ability to isolate and better characterize these therapy-resistant cells is critical for the future development of targeted therapies aimed at achieving more robust and long-lasting responses. Using a novel application for the prolife...

  19. Interferons Increase Cell Resistance to Staphylococcal Alpha-Toxin▿

    OpenAIRE

    Yarovinsky, Timur O.; Monick, Martha M.; Husmann, Matthias; Hunninghake, Gary W.

    2007-01-01

    Many bacterial pathogens, including Staphylococcus aureus, use a variety of pore-forming toxins as important virulence factors. Staphylococcal alpha-toxin, a prototype β-barrel pore-forming toxin, triggers the release of proinflammatory mediators and induces primarily necrotic death in susceptible cells. However, whether host factors released in response to staphylococcal infections may increase cell resistance to alpha-toxin is not known. Here we show that prior exposure to interferons (IFNs...

  20. Radiation resistance of some microorganisms isolated from irradiated herbs

    International Nuclear Information System (INIS)

    Three types of Egyptian medicinal herbs, sweet marjoram, spearmint and thyme were used in this study. The tested herbs were exposed to gamma radiation doses ranging from 1.0 to 10,0 kGy. The sublethal doses of radioresistant molds ranged from 1.0 to 2.0 kGy and the sublethal doses of radioresistant bacteria ranged from 7.0 to 8.0 kGy. The radioresistant molds isolated from sweet marjoram and spearmint herbs were identified as Aspergillus, whereas that isolated from thyme was identified as Aspergillus ochraceus. The radioresistant bacteria isolated from sweet marjoram, spearmint and thyme were identified as Bacillus megaterium, B.pantothenticus and B. brevis, respectively. All the radioresistant molds exhibited an exponential response. The D15value of Asp. ochraceus was 0.33 kGy, while that of Asp. niger were 0.45 and 0.5 kGy, respectively. All the bacterial species exhibited non-exponential response. The D10 -values for B.megaterium, B. pantothenticus and B. brevis were found to be 2.58, 3.0 and 1.63 kGy, respectively

  1. Radiation-induced changes to mammalian cells as a precipitating factor in somatic radiation injuries

    International Nuclear Information System (INIS)

    Radiation-induced inhibitions of proliferation were assessed in cell cultures examined for their colony-forming abilities as well as from changes of growth curves. The results of those measurements, along with simulating calculations, underlined the fact that the colony-forming capacity of a cell can by no means be equated with cell survival, unless due attention is given to the size of the colony formed. It is the size of the colony that provides a measure of the damage done to the irradiated cell. Cells counts are the most reliable method to ascertain the course of proliferation following radiation exposure. The difference between the two methods mentioned became particularly evident in studies with radiation protection substances. Dithiothreitol (DTT) and mercaptopropionyl glycine (MPG) were on the basis of colony formation clearly shown to offer protection against radiation. The growth curves, however, revealed that the proliferation of cells irradiated in the presence of radiation protection substances was even more strongly inhibited than that of cells influenced by irradiation alone. The neutral elution method failed to provide irrefutable evidence that the rate of double strand breaks was reduced by those two substances. Cysteamine and DTT were, however, able to inhibit radiation-induced changes to the proteins of human erythrocyte membranes. (orig./MG)

  2. Resistance to the ionizing radiation in cells of human melanoma. Role of the antioxidant enzymes and of the free radicals of the oxygen; Resistencia a la radiacion ionizante en celulas de melanoma humano. Papel de las enzimas antioxidantes y de los radicales libres del oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Medina, V.; Cricco, G.; Massari, N.; Nunez, M.; Martin, G.; Mohanad, N.; Gutierrez, A.; Bergoc, R.; Rivera, E. [Laboratorio de Radioisotopos, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Junin 956, Buenos Aires (Argentina); Crescenti, E.; Croci, M. [Instituto de Inmunooncologia, Cordoba 3200, Buenos Aires (Argentina)]. e-mail: vmedina@ffyb.uba.ar

    2006-07-01

    The malignant melanoma is a highly aggressive and potentially lethal type of skin cancer. Previously we have reported that the cellular human lines of melanoma WM35 and M15 are resistant to the ionizing radiation (IR). The histamine (HA) although it has a regulator effect of the cellular proliferation in these lines, it is not capable of to modify the response to the IR like it makes with other malignant cellular lines. To investigate the bases of the radioresistance of the melanoma lines we have studied in the WM35 the production of free radicals of oxygen (ROS), the activity of the antioxidant enzymes and their modifications by action of the IR and of the HA. In studies in vitro the cells were treated with HA 10 {mu}M from 20 hs before being irradiated with a dose of 2 Gy (source {sup 137}Cs, dose rate 7.7 Gy/min). The ROS levels, superoxide anion (O{sub 2}{sup -}) and hydrogen peroxide (H{sub 2}O{sub 2}) its were measured by flow cytometry using fluorescent coloring and the activity of dismutase superoxide (SOD), Catalase (CAT) and Glutathion Peroxidase (GPx) its were determined by spectrophotometric techniques and the protein levels by Western blot. The results indicate that in the cells WM35 the HA increases the production of H{sub 2}O{sub 2} in 96% and it diminishes lightly (17%) the levels of O{sub 2}{sup -} . On the contrary, the IR diminishes the levels of H{sub 2}O-2 in 47% and it increases in 46% those of O{sub 2}{sup -}. In the irradiated cells the HA power the decrease of H{sub 2}O{sub 2} produced by the IR. The variation of the enzymes activity is coincident with these changes in the levels of ROS: the treatment with HA increases the activity of SOD and it diminishes that of CAT in cells without irradiating; on the other hand, in the irradiated cells the HA it diminishes the SOD significantly. On the base of these results we can conclude that the levels of H{sub 2}O{sub 2} are directly related with the sensitivity of the cells WM35 to the IR. The HA

  3. Colorectal cancer cell lines made resistant to SN38-and Oxaliplatin: Roles of altered ion transporter function in resistance?

    DEFF Research Database (Denmark)

    Sandra, Christensen; Jensen, Niels Frank; Stoeckel, Johanne Danmark; Belling, Kirstine C.; Romer, Maria Unni; Gupta, Ramneek; Brunner, Nils; Pedersen, Stine Helene Falsig; Stenvang, Jan

    2013-01-01

    resistance in HCT-116, HT-29 and LoVo cells. Microarray analysis and qPCR validation showed that mRNA expression of glutamate transporters SLC1A1 and SLC1A3 were markedly altered in resistant cells. Remarkably, mRNA levels of SLC1A3 were increased by ~40-and ~2500-fold in SN38-and Oxp-resistant HT29 cells...

  4. Open Cell Conducting Foams for High Synchrotron Radiation Beam Liners

    OpenAIRE

    Petracca, Stefania; Stabile, Arturo

    2014-01-01

    The possible use of open-cell conductive foams in high synchrotron radiation particle accelerator beam liners is considered. Available materials and modeling tools are reviewed, potential pros and cons are discussed, and preliminary conclusions are drawn.

  5. Engineering hot-cell windows for radiation protection

    International Nuclear Information System (INIS)

    Radiation protection considerations in the design and construction of hot-cell windows are discussed. The importance of evaluating the potential gamma spectra and neutron source terms is stressed. 11 references

  6. miR-193a-3p regulation of chemoradiation resistance in oesophageal cancer cells via the PSEN1 gene.

    Science.gov (United States)

    Meng, Fang; Qian, Liting; Lv, Lei; Ding, Bojin; Zhou, Gieping; Cheng, Xu; Niu, Sanqiang; Liang, Yu

    2016-04-01

    Chemoradiation therapy is an important component of the curative treatment for oesophageal carcinomas. These therapeutic effects are prevented in patients according to radioresistance and multi-drug resistance, and the cause of such resistance remains unclear. In this study, we identified the role of miR-193a-3p in modulating the radioresistance and chemoresistance of oesophageal cancer cells. We found that KYSE150 and KYSE410 cells could be characterized as relatively radiation-sensitive and radiation-resistant cells, respectively. Similarly, KYSE150 and KYSE410 cells were found to be chemosensitive and chemoresistant, respectively. Over-expression of miR-193a-3p increased the radioresistance and chemoresistance of oesophageal squamous cell carcinoma (ESCC) cells. In contrast, the down-regulation of miR-193a-3p decreased the radioresistance and chemoresistance of ESCC cells. In addition, miR-193a-3p inducing DNA damage has also been demonstrated through measuring the level of gamma-H2AX associated with miR-193a-3p. Moreover, a small interfering RNA(siRNA)-induced repression of the PSEN1 gene had an effect similar to that of miR-193a-3p up-regulation. The above processes also inhibited oesophageal cancer cells apoptosis. These findings suggest that miR-193a-3p contributes to the radiation and chemotherapy resistance of oesophageal carcinoma by down-regulating PSEN1. Thus, miR-193a-3p and PSEN1 might be potential biomarkers for chemoradiation resistant cancers. PMID:26743123

  7. Identification of genes associated with cisplatin resistance in human oral squamous cell carcinoma cell line

    Directory of Open Access Journals (Sweden)

    Zhang Ping

    2006-09-01

    Full Text Available Abstract Background Cisplatin is widely used for chemotherapy of head and neck squamous cell carcinoma. However, details of the molecular mechanism responsible for cisplatin resistance are still unclear. The aim of this study was to identify the expression of genes related to cisplatin resistance in oral squamous cell carcinoma cells. Methods A cisplatin-resistant cell line, Tca/cisplatin, was established from a cisplatin-sensitive cell line, Tca8113, which was derived from moderately-differentiated tongue squamous cell carcinoma. Global gene expression in this resistant cell line and its sensitive parent cell line was analyzed using Affymetrix HG-U95Av2 microarrays. Candidate genes involved in DNA repair, the MAP pathway and cell cycle regulation were chosen to validate the microarray analysis results. Cell cycle distribution and apoptosis following cisplatin exposure were also investigated. Results Cisplatin resistance in Tca/cisplatin cells was stable for two years in cisplatin-free culture medium. The IC50 for cisplatin in Tca/cisplatin was 6.5-fold higher than that in Tca8113. Microarray analysis identified 38 genes that were up-regulated and 25 that were down-regulated in this cell line. Some were novel candidates, while others are involved in well-characterized mechanisms that could be relevant to cisplatin resistance, such as RECQL for DNA repair and MAP2K6 in the MAP pathway; all the genes were further validated by Real-time PCR. The cell cycle-regulated genes CCND1 and CCND3 were involved in cisplatin resistance; 24-hour exposure to 10 μM cisplatin induced a marked S phase block in Tca/cisplatin cells but not in Tca8113 cells. Conclusion The Tca8113 cell line and its stable drug-resistant variant Tca/cisplatin provided a useful model for identifying candidate genes responsible for the mechanism of cisplatin resistance in oral squamous cell carcinoma. Our data provide a useful basis for screening candidate targets for early diagnosis

  8. Identification of genes associated with cisplatin resistance in human oral squamous cell carcinoma cell line

    International Nuclear Information System (INIS)

    Cisplatin is widely used for chemotherapy of head and neck squamous cell carcinoma. However, details of the molecular mechanism responsible for cisplatin resistance are still unclear. The aim of this study was to identify the expression of genes related to cisplatin resistance in oral squamous cell carcinoma cells. A cisplatin-resistant cell line, Tca/cisplatin, was established from a cisplatin-sensitive cell line, Tca8113, which was derived from moderately-differentiated tongue squamous cell carcinoma. Global gene expression in this resistant cell line and its sensitive parent cell line was analyzed using Affymetrix HG-U95Av2 microarrays. Candidate genes involved in DNA repair, the MAP pathway and cell cycle regulation were chosen to validate the microarray analysis results. Cell cycle distribution and apoptosis following cisplatin exposure were also investigated. Cisplatin resistance in Tca/cisplatin cells was stable for two years in cisplatin-free culture medium. The IC50 for cisplatin in Tca/cisplatin was 6.5-fold higher than that in Tca8113. Microarray analysis identified 38 genes that were up-regulated and 25 that were down-regulated in this cell line. Some were novel candidates, while others are involved in well-characterized mechanisms that could be relevant to cisplatin resistance, such as RECQL for DNA repair and MAP2K6 in the MAP pathway; all the genes were further validated by Real-time PCR. The cell cycle-regulated genes CCND1 and CCND3 were involved in cisplatin resistance; 24-hour exposure to 10 μM cisplatin induced a marked S phase block in Tca/cisplatin cells but not in Tca8113 cells. The Tca8113 cell line and its stable drug-resistant variant Tca/cisplatin provided a useful model for identifying candidate genes responsible for the mechanism of cisplatin resistance in oral squamous cell carcinoma. Our data provide a useful basis for screening candidate targets for early diagnosis and further intervention in cisplatin resistance

  9. Mechanism of multidrug resistance of human small cell lung cancer cell line H446/VP

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-ling; YAN Yun-li; ZHOU Na-jing; HAN Shuo; ZHAO Jun-xia; CAO Cui-li; Lü Yu-hong

    2010-01-01

    Background Small cell lung cancer (SCLC) is the most aggressive form of lung cancer. This study aimed to investigate the mechanism of human small cell lung cancer cell line resistance to etoposide (VP-16), H446/VP.Methods The cell viability was measured by M∏ assay. Immunocytochemistry, reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting methods were used to detect the multidrug resistance gene (MDR1), bcl-2, bax and the topoisomerase Ⅱ (Topo Ⅱ) expressions in H446 and H446/VP cells after treated with or without VP-16.Results The 50% inhibition concentration (IC50) of VP-16 on H446 cells was 49 mg/L, and 836 mg/L was for H446/VP cells. The expressions of MDR1 and bcl-2 were up-regulated, while the amounts of bax and Topo Ⅱ were reduced in H446/VP cells. After treated with 49 mg/L of VP-16, it showed that the drug could significantly inhibit bcl-2 and Topo Ⅱ expressions, and increase bax expression in H446 cells compared with that of H446/VP cells.Conclusions The H446/VP cell was stably resistant to VP-16. The decreased expression of Topo Ⅱ was correlated with the H446/VP multidrug resistance. The elevated expressions of MDR1, and the altered apoptotic pathways also played an important role in VP-16 induced multidrug resistance of SCLC.

  10. Mammalian cells exposed to ionizing radiation: Structural and biochemical aspects.

    Science.gov (United States)

    Sabanero, Myrna; Azorín-Vega, Juan Carlos; Flores-Villavicencio, Lérida Liss; Castruita-Dominguez, J Pedro; Vallejo, Miguel Angel; Barbosa-Sabanero, Gloria; Cordova-Fraga, Teodoro; Sosa-Aquino, Modesto

    2016-02-01

    Acute or chronic exposure to ionizing radiation is a factor that may be hazardous to health. It has been reported that exposure to low doses of radiation (less than 50 mSv/year) and subsequently exposure to high doses produces greater effects in people. It has been reported that people who have been exposed to low doses of radiation (less than 50 mSv/year) and subsequently are exposed to high doses, have greater effects. However, at a molecular and biochemical level, it is an unknown alteration. This study, analyzes the susceptibility of a biological system (HeLa ATCC CCL-2 human cervix cancer cell line) to ionizing radiation (6 and 60 mSv/90 s). Our research considers multiple variables such as: total protein profile, mitochondrial metabolic activity (XTT assay), cell viability (Trypan blue exclusion assay), cytoskeleton (actin microfilaments), nuclei (DAPI), and genomic DNA. The results indicate, that cells exposed to ionizing radiation show structural alterations in nuclear phenotype and aneuploidy, further disruption in the tight junctions and consequently on the distribution of actin microfilaments. Similar alterations were observed in cells treated with a genotoxic agent (200 μM H2O2/1h). In conclusion, this multi-criteria assessment enables precise comparisons of the effects of radiation between various line cells. However, it is necessary to determine stress markers for integration of the effects of ionizing radiation. PMID:26656429

  11. Apoptosis of smooth muscle cells induced by radiation

    International Nuclear Information System (INIS)

    Objective: To study the effects and mechanism of 188Re on apoptosis of cultured smooth muscle cells (SMCs), and to explore the value of radiation induced SMCs apoptosis for preventing restenosis. Methods: The SMCs cultured in vitro were irradiated by 188Re with different doses. The trypan blue exclusion test, flow cytometry, JAM test, transmission electron microscopy and immunocytochemistry assay were used to investigate the effects of β-particles on apoptosis of SMCs, such as cell viability, cell apoptosis rate, DNA fragmentation, cell ultrastructural changes and related gene expression. Results: There were no significant changes of SMCs viability, cell apoptosis rate, DNA fragmentation and cellular ultrastructure in low-dose irradiation group, compared with control group. High-dose radiation (>2.96 GBq/L) on SMCs showed that viable cell proportion was markedly decreased, while cell apoptosis rate and DNA fragmentation were significantly increased, and cellular ultrastructure was destroyed. The expression of p53, bax gene was up regulated and bcl-2/bax was decreased while SMCs apoptosis occurred. Conclusions: Low-dose radiation on SMCs, which could inhibit completely SMCs proliferation, did not show any effects on cell viability, cell apoptosis rate, cell ultrastructure and DNA fragmentation. High-dose radiation could result in significant SMCs apoptosis. Up-regulated p53, bcl-2 and bax gene took a part in cell apoptosis induced by radiation. Low-dose and low-dose rate radiation appeared to be an ideal intravascular radiotherapy for preventing restenosis, which could not only inhibit SMCs proliferation, but also preserve cell viability and integrity

  12. The role of protective systems in cell homeostasis upon gamma radiation

    International Nuclear Information System (INIS)

    There are a number of parameters that are used for the estimation of cell defence against radiation and chemicals: induced initial DNA damage, residual damage after a period of repair, rate and fidelity of repair, endpoint (chromosomal changes and cell survival). Antioxidant enzymes are main pathway of cell defence: superoxide dismutase (SOD), catalase, glutatione peroxidase, glutatione-S-transferase et al. Key enzyme is SOD which naturalizes reactive oxygen species (ROS). ROS are main damaging component of the radiation and some chemical action. Glutatione-S-transferase (GST) conjugates ROS to glutatione prior to their excretion from the body. The GST M1 null (one from family of GST) genotype is found in about 50% Europeans, Japanese, but only one-quarter of Afro-Americans. Lack of this enzyme may result in deficient detoxification leading to increase sensitivity to mutagens and in risk of cancer. Another system of cell defence involves enzymes taking part in DNA repair: base excision repair, nucleotide excision repair, mismatch repair et al. A radio adaptive response (RAR) also can serve as cell defence system. RAR forms a cell resistance to gamma-radiation after cell pretreatment with low doses of radiation and some incubation (3-4 hours). Purpose of our investigation: 1) to estimate the role of SOD in human cells isolated from healthy donors, children with some repair-deficient diseases (Bloom syndrome, Marfan syndrome) and children from area with an increased level of radiation; 2) to compare SOD activity in human cells and human cells during RAR; 3) to study a possible link between cell survival and initial damage of DNA after treatment with TRIEN - inhibitor of SOD - and with garlic extract - natural anti mutagen. We found the increased level of damage of DNA in trien-pretreated cells (healthy and repair-deficient cells). However this level was similar in lymphocytes of children from areas with an increased level of radiation without and with trien

  13. Radiation protective effect of hypoxia-inducible factor-1α (HIF-1α) on human oral squamous cell carcinoma cell lines

    International Nuclear Information System (INIS)

    We examined the effects of 5-Gy radiation on the expression of hypoxia-inducible factor-1α (HIF-1α) and the radiosensitivity of five human oral squamous cell carcinoma (OSCC) cell lines (SAS, Ca9-22, TT, BSC-OF and IS-FOM). In all of the cell lines, HIF-1α was expressed in mRNA, and radiation had no influence on gene transcription. The number of apoptotic cells increased 72 h after irradiation in cell lines SAS, Ca9-22 and TT cells, indicating low transcriptional levels of HIF-1α, and the levels of non-cleaved caspase-3, an executioner of apoptosis, and non-cleaved poly (adenosine diphosphate-ribose) polymerase (PARP), a marker of DNA damage early in apoptosis, decreased simultaneously. Conversely, radiation failed to induce apoptosis or to decrease expression of non-cleaved caspase-3 and PARP in cell-lines BSC-OF and IS-FOM cells that expressed high levels of HIF-1α. BSC-OF and IS-FOM cells exhibited high migratory capacity. When CoCl2 was present in the medium, HIF-1α expression increased along with the survival of Ca9-22 cells after radiation exposure. These results suggest that OSCC cells expressing high levels of HIF-1α are resistant to radiation. HIF-1α can be used to control the short term radiosensitivity of cells. (authors)

  14. The inverse correlation between series resistance and parallel resistance of small molecule organic solar cells

    Institute of Scientific and Technical Information of China (English)

    Kewei Wang; Yufeng Zheng; Gu Xu; Xiuping Xu

    2015-01-01

    Understanding the inversely correlated series resistance (Rs) and parallel resistance (Rp) remains a challenge. Here we report that the variation of Rs and Rp is inversely related through the morphology of the donor and acceptor interface in CuPc organic solar cells, when comparing the bilayer structure and bulk heterojunction structure. It was also found that the charge carrier concentration near the donor–acceptor interface plays an important role in the relationships of Rs and Rp under fixed interfacial morphology, which was verified by the change of Voc. The inversely correlated Rs and Rp contributes to the improvement of the fill factor, and in turn the power conversion efficiency.

  15. Tamoxifen-resistant breast cancer cells possess cancer stem-like cell properties

    Institute of Scientific and Technical Information of China (English)

    LIU Hui; ZHANG Heng-wei; SUN Xian-fu; GUO Xu-hui; HE Ya-ning; CUI Shu-de; FAN Qing-xia

    2013-01-01

    Background Cancer stem cells (CSCs) are the cause of cancer recurrence because they are resistant to conventional therapy and contribute to cancer growth and metastasis.Endocrinotherapy is the most common breast cancer therapy and acquired tamoxifen (TAM) resistance is the main reason for endocrinotherapy failure during such therapy.Although acquired resistance to endocrine treatment has been extensively studied,the underlying mechanisms are unclear.We hypothesized that breast CSCs played an important role in TAM-induced resistance during breast cancer therapy.Therefore,we investigated the biological characteristics of TAM-resistant (TAM-R) breast cancer cells.Methods Mammosphere formation and tumorigenicity of wild-type (WT) and TAM-R MCF7 cells were tested by a mammosphere assay and mouse tumor xenografts respectively.Stem-cell markers (SOX-2,OCT-4,and CD133) and epithelial-mesenchymal transition (EMT) markers were tested by quantitative real-time (qRT)-PCR.Morphological observation was performed to characterize EMT.Results After induction of TAM resistance,TAM-R MCF7 cells exhibited increased proliferation in the presence of TAM compared to that of WT MCF7 cells (P <0.05),indicating enhanced TAM resistance of TAM-R MCF7 cells compared to that of WT MCF7 cells.TAM-R MCF7 cells showed enhanced mammosphere formation and tumorigenicity in nude mice compared to that of WT MCF7 cells (P <0.01),demonstrating the elevated CSC properties of TAM-R MCF7 cells.Consistently,qRT-PCR revealed that TAM-R MCF7 cells expressed increased mRNA levels of stem cell markers including SOX-2,OCT-4,and CD133,compared to those of WT MCF7 cells (P <0.05).Morphologically,TAM-R MCF7 cells showed a fibroblastic phenotype,but WT MCF7 cells were epithelial-like.After induction of TAM resistance,qRT-PCR indicated that MCF7 cells expressed increased mRNA levels of Snail,vimentin,and N-cadherin and decreased levels of E-cadherin,which are considered as EMT characteristics (P <0

  16. Ionizing radiation and cell cycle progression in ataxia telangiectasia

    International Nuclear Information System (INIS)

    Exposure of mammalian cells to ionizing radiation causes delay in normal progress through the cell cycle at a number of different checkpoints. Abnormalities in these checkpoints have been described for ataxia telangiectasia cells after irradiation. In this report we show that these abnormalities occur at different phases in the cell cycle in several ataxia telangiectasia lymphoblastoid cells. Ataxia telangiectasia cells, synchronized in late G1 phase with either mimosine or aphidicolin and exposed to radiation, showed a reduced delay in entering S phase compared to irradiated control cells. Failure to exhibit G1-phase delay in ataxia telangiectasia cells is accompanied by a reduced ability of radiation to activate the product of the tumor suppressor gene p53, a protein involved in G1/S-phase delay. When the progress of irradiated G1-phase cells was followed into the subsequent G2 and G1 phases ataxia telangiectasia cells showed a more pronounced accumulation in G2 phase than control cells. When cells were irradiated in S phase and extent of delay was more evident in G2 phase and ataxia telangiectasia cells were delayed to a greater extent. These results suggest that the lack of initial delay in both G1 and S phases to the radiosensitivity observed in this syndrome. 26 refs., 3 figs., 2 tabs

  17. Immobilization of yeast cells by radiation-induced polymerization

    International Nuclear Information System (INIS)

    Radiation-induced polymerization method was applied to the immobilization of yeast cells. The effects of irradiation, cooling and monomer, which are neccessary for polymerization, were recovered completely by subsequent aerobical incubation of yeast cells. The ethanol productive in immobilized yeast cells increased with the increase of aerobical incubation period. The growth of yeast cells in immobilized yeast cells was indicated. The maximum ethanol productivity in immobilized yeast cell system was around three times as much as that in free yeast cell system. (orig.)

  18. Studies on radiation resistance of fiber reinforced plastic composites featured by easiness of manufacturing, 3

    International Nuclear Information System (INIS)

    Mechanical properties of glass fiber-reinforced plastics (GFRP) irradiated at room temperature with electron beams were studied in order to characterize the radiation resistance. Mechanical properties were tested by flexural strength and interlaminar shear strength (ILSS) at room and low temperature, and flexural fatigue strength at room temperature. The GFRP used in the present study were manufactured trial with three kinds of epoxy matrices having excellent radiation resistance at room temperature and easiness of manufacturing. These composites prepared in selected curing condition were equipped with high flexural strength at low temperature, about two times at room temperature. GFRP composed of 4,4'-tetraglycidyl diamino diphenyl methane cured with 4,4'-diamino diphenyl methane showed the highest radiation resistance: the strength after irradiation up to 90 MGy were kept the initial value, that is, flexural strength of 1000 MPa at 77 K and ILSS of 70 MPa at 123 K. It was also confirmed that the flexural strength measured at 4.2 K were well agreed with the values tested at 77 K. On the effects of fiber-matrix bonding materials by using different kinds and/or amount of silane coupling agents, the pronounced difference were found in the degradation behavior but did not affect to the flexural strength of the GFRP. Flexural fatigue behavior showed rather well radiation degradation comparing with three point bending strength at room temperature. (author)

  19. Fabrication and characterization of radiation-resistant LDPE/MWCNT nanocomposites

    Science.gov (United States)

    Jung, Chan-Hee; Lee, Dong-Hoon; Hwang, In-Tae; Im, Don-Sun; Shin, Junhwa; Kang, Phil-Hyun; Choi, Jae-Hak

    2013-07-01

    In this study, multi-walled carbon nanotube (MWCNT)-reinforced low density polyethylene (LDPE) nanocomposites were fabricated to improve the radiation resistance of LDPE. LDPE nanocomposites with various compositions prepared through a melt blending were irradiated by γ-rays at doses ranging from 50 to 500 kGy. The resulting nanocomposites were investigated in terms of their morphology, tensile property, activation energy, oxidation stability, thermal stability, and lifetime. Based on the results of the field emission scanning electron microscope (FE-SEM) analysis, MWCNTs were found to be well-dispersed in the LDPE matrix even at 3 wt.%, and no radiation-induced morphological changes were observed. The analytic results of the tensile property, oxidative stability, and activation energy revealed that the LDPE/MWCNT nanocomposites exhibited a higher radiation resistance in comparison to the pure LDPE, which was dependent on the MWCNT content. Moreover, based on the lifetime prediction, the lifetime of the LDPE/MWCNT was much longer than that of the pure LDPE. This improved radiation resistance can be ascribed to the incorporation of the radical scavenging MWCNT nanofillers into the LDPE matrix.

  20. Radiation resistance of pyrocarbon-boned fuel and absorbing elements for HTGR

    International Nuclear Information System (INIS)

    In choosing the reactor type, problems of nuclear and radiation safety are outstanding. The analysis of the design and experiments show that HTGR type reactors helium cooled satisfy all the safety requirements. It has been planned in the Soviet Union to construct two HTGR plants, VGR-50 and VG-400. Later it was decided to construct an experimental plant with a low power high temperature reactor (VGM). Spherical uranium-graphite fuel elements with coated fuel particles are supposed to be used in HTGR core. A unique technology for producing spherical pyrocarbon-bound fuel and absorbing elements of monolithic type has been developed. Extended tests were done to to investigate fuel elements behaviour: radiation resistance of coated fuel particles with different types of fuel; influence of the coated fuel particles design on gaseous fission products release; influence of non-sphericity on coated fuel particle performance; dependence of gaseous fission products release from fuel elements on the thickness of fuel-free cans; confining role of pyrocarbon as a factor capable of diminishing the rate of fission products release; radiation resistance of spherical fuel elements during burnup; radiation resistance of spherical absorbing elements to fast neutron fluence and boron burnup

  1. Radiation resistance of (Ni,Fe)Cr2O4 spinels by molecular dynamics simulations

    International Nuclear Information System (INIS)

    Molecular dynamics simulations are carried out to study primary radiation damage in NiCr2O4 and FeCr2O4 spinels, which are part of the corrosion layer of the vapour generators used in nuclear reactors. The radiation resistance of both spinels is evaluated by studying point defect recombination processes, threshold displacement energies, and 20 keV displacement cascades initiated with different PKA masses. Results are mainly in agreement with previous studies involving MgAl2O4 showing that radiation facilitates the transition to inverse spinel structure or NaCl structure. However, we find some differences between the two studied spinels indicating that NiCr2O4 is more sensitive to radiation

  2. Radiation resistance of (Ni,Fe)Cr2O4 spinels by molecular dynamics simulations

    Science.gov (United States)

    Van Brutzel, Laurent; Alvarez, Pierre; Chartier, Alain

    2014-05-01

    Molecular dynamics simulations are carried out to study primary radiation damage in NiCr2O4 and FeCr2O4 spinels, which are part of the corrosion layer of the vapour generators used in nuclear reactors. The radiation resistance of both spinels is evaluated by studying point defect recombination processes, threshold displacement energies, and 20 keV displacement cascades initiated with different PKA masses. Results are mainly in agreement with previous studies involving MgAl2O4 showing that radiation facilitates the transition to inverse spinel structure or NaCl structure. However, we find some differences between the two studied spinels indicating that NiCr2O4 is more sensitive to radiation.

  3. REDD1 protects osteoblast cells from gamma radiation-induced premature senescence.

    Directory of Open Access Journals (Sweden)

    Xiang Hong Li

    Full Text Available Radiotherapy is commonly used for cancer treatment. However, it often results in side effects due to radiation damage in normal tissue, such as bone marrow (BM failure. Adult hematopoietic stem and progenitor cells (HSPC reside in BM next to the endosteal bone surface, which is lined primarily by hematopoietic niche osteoblastic cells. Osteoblasts are relatively more radiation-resistant than HSPCs, but the mechanisms are not well understood. In the present study, we demonstrated that the stress response gene REDD1 (regulated in development and DNA damage responses 1 was highly expressed in human osteoblast cell line (hFOB cells after γ irradiation. Knockdown of REDD1 with siRNA resulted in a decrease in hFOB cell numbers, whereas transfection of PCMV6-AC-GFP-REDD1 plasmid DNA into hFOB cells inhibited mammalian target of rapamycin (mTOR and p21 expression and protected these cells from radiation-induced premature senescence (PS. The PS in irradiated hFOB cells were characterized by significant inhibition of clonogenicity, activation of senescence biomarker SA-β-gal, and the senescence-associated cytokine secretory phenotype (SASP after 4 or 8 Gy irradiation. Immunoprecipitation assays demonstrated that the stress response proteins p53 and nuclear factor κ B (NFkB interacted with REDD1 in hFOB cells. Knockdown of NFkB or p53 gene dramatically suppressed REDD1 protein expression in these cells, indicating that REDD1 was regulated by both factors. Our data demonstrated that REDD1 is a protective factor in radiation-induced osteoblast cell premature senescence.

  4. beta1-integrin-mediated signaling essentially contributes to cell survival after radiation-induced genotoxic injury

    DEFF Research Database (Denmark)

    Cordes, N; Seidler, J; Durzok, R; Geinitz, H; Brakebusch, C

    2006-01-01

    Integrin-mediated adhesion to extracellular matrix proteins confers resistance to radiation- or drug-induced genotoxic injury. To analyse the underlying mechanisms specific for beta1-integrins, wild-type beta1A-integrin-expressing GD25beta1A cells were compared to GD25beta1B cells, which express...... findings in tumor cells, human A-172 glioma cells were examined under the same conditions after siRNA-mediated silencing of beta1-integrins. We found that beta1A-integrin-mediated adhesion to fibronectin, collagen-III or beta1-IgG was essential for cell survival after radiation-induced genotoxic injury...... central role of beta1-integrins in Akt- and p130Cas/paxillin-mediated prosurvival signaling. These findings suggest beta1-integrins as critical regulators of cell survival after radiation-induced genotoxic injury. Elucidation of the molecular circuitry of prosurvival beta1-integrin-mediated signaling in...

  5. Cell Biological Mechanisms of Multidrug Resistance in Tumors

    Science.gov (United States)

    Simon, Sanford M.; Schindler, Melvin

    1994-04-01

    Multidrug resistance (MDR) is a generic term for the variety of strategies tumor cells use to evade the cytotoxic effects of anticancer drugs. MDR is characterized by a decreased sensitivity of tumor cells not only to the drug employed for chemotherapy but also to a broad spectrum of drugs with neither obvious structural homology nor common targets. This pleotropic resistance is one of the major obstacles to the successful treatment of tumors. MDR may result from structural or functional changes at the plasma membrane or within the cytoplasm, cellular compartments, or nucleus. Molecular mechanisms of MDR are discussed in terms of modifications in detoxification and DNA repair pathways, changes in cellular sites of drug sequestration, decreases in drug-target affinity, synthesis of specific drug inhibitors within cells, altered or inappropriate targeting of proteins, and accelerated removal or secretion of drugs.

  6. Radiation-induced genetic effects in germ cells of mammals

    International Nuclear Information System (INIS)

    The possibility of the induction of malformations after radiation exposure during pregnancy is a serious radiation hazard. The objectives of the project refer to radiation exposure of germ cell stages with different radiation qualities (X-, gamma- or beta-rays) and different dose rates (1 Gy/min and below 0.01 Gy/min). The uterine content is examined on day 19 of gestation as to early and late resorptions, dead and malformed fetuses and fetal weights are determined. (R.P.) 4 refs., 1 tab

  7. Studies on radiation resistance of fiber reinforced plastic composites featured by easiness of manufacturing, 1

    International Nuclear Information System (INIS)

    Degradation behavior of fiber reinforced plastic(FRP) composite materials manufactured by conventional lamination technology was studied by measuring various mechanical properties after irradiation and observing fracture surfaces by scanning electron microscopy. When bisphenol-A type epoxy was used as matrix material, the laminated composites degraded rapidly. This fact was ascribed to poor radiation resistance of the matrix resin. The radiation resistance varied depending on types of hardeners. Diaminodiphenylmethane(DDM) gave radiation resistance higher than diaminodiphenylsulfone(DDS). The dose that produced an incipient decrease in mechanical properties(threshold dose) was larger in case of carbon fiber reinforcement than glass fiber reinforcement. For example, the threshold dose was about 10 MGy in case of glass fiber reinforcement with epoxy matrix hardened by DDS, and about 30 MGy when hardened by DDM. While, it increased to about 60 MGy with the latter matrix when carbon fiber is used. From the results of scanning electron microscopic observation of fractured surfaces, the superior radiation resistance in case of carbon fiber reinforcement was found due to its stable bonding interface between fiber and matrix. When BT(bismaleimide-triazine) resin was used as matrix for glass fiber reinforcement, little influence of irradiation was observed in various mechanical properties at least up to 60 MGy, and three point flexural strength showed no change even up to 100 MGy. This stability was ascribed to the stability of both the matrix resin and the bonding interface. Interlaminar shear strength reflects radiation effects on FRP with highest sensitivity among various mechanical properties tested in this work. (author)

  8. Coxsackie-adenovirus receptor as a novel marker of stem cells in treatment-resistant non-small cell lung cancer

    International Nuclear Information System (INIS)

    Background: Treatment resistance resulting from the presence of cancer stem cells (CSCs) remains a challenge in cancer treatment. Little is known about possible markers of CSCs in treatment-resistant non-small cell lung cancer (NSCLC). We explored the coxsackie-adenovirus receptor (CAR) as one such marker of CSCs in models of treatment-resistant NSCLC. Materials and methods: Resistant H460 and A549 cell lines were established by repeated exposure to paclitaxel or fractionated radiation. CSC markers were measured by Western blotting and flow cytometry. We also established stable CAR-overexpressing and stable shRNA-CAR-knockdown cell lines and assessed their survival, invasiveness, and tumorigenic capabilities with clonogenic, telomerase, Matrigel, and tumor formation assays. Results: CAR expression was associated with CSC phenotype both in vitro and in vivo. CAR-overexpressing cells were more treatment-resistant, self-renewing, and tumorigenic than were parental cells, and shRNA-mediated knockdown of CAR expression was sufficient to inhibit these functions. CAR expression also correlated with the epithelial–mesenchymal transition. Conclusions: We showed for the first time that CAR is a marker of CSCs and may affect the activities of CSCs in treatment-resistant NSCLC. CAR may prove to be a target for CSC treatment and a predictor of treatment response in patients with NSCLC.

  9. Cellular heredity in haploid cultures of somatic cells. Comprehensive report, April 1975--June 1977. [UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Freed, J.J.

    1977-07-01

    This report reviews genetic studies carried out since 1975 on a haploid cultured cell line from frog embryos (ICR 2A). Although a single chromosome set would be expected to facilitate recovery of recessive mutants, experiments suggested that cell culture variants might arise through processes more complex than the selection of simple mutational changes. Therefore, the objectives of the work reported here have been to throw light on just how cell culture variants arise in this system. First, we have continued to characterize the ICR 2A line, with emphasis on stability of karyotype and DNA content. Second, we have studied in detail the origin of two classes of drug-resistant variants. Bromodeoxyuridine resistance of the thymidine deficiency type has been shown to arise through sequential loss of two forms of thymidine-phosphorylating enzyme; loss of the second form of enzyme is complex, suggesting that changes more complex than simple recessive mutations may be involved. Another form of resistance, in which tolerance of high levels of bromodeoxyuridine is found in cells that continue to express thymidine kinase, remains under study. Variants resistant to microtubule inhibitors were isolated. It was found that these haploid strains have properties distinguishing them from analogous resistant strains isolated from diploid mammalian cell cultures in other laboratories. In order to understand better how mutagens are involved in the origin of cell culture variants, we have examined the effect of different forms of DNA repair on the frequency of drug-resistant colonies induced by ultraviolet radiation. Preliminary experiments suggest that the frequency of such colonies is greater when repair takes place through (presumably error-prone) dark repair than when (error-free) photoreversal is allowed to occur. Such experiments can determine whether new phenotypes arise from alterations in DNA, and thus whether, in a broad sense, they are likely to be mutational in nature.

  10. Cybernetical investigations on the radiation effects on tumour cells

    International Nuclear Information System (INIS)

    The goal of this work was to find suitable conditions for the in-vitro investigations with these E.A.T. cells so that basic experiments carried out with yeast cells will also be possible. Systematic investigations on cell multiplication led to reliable and definite test conditions for these cells. For the evaluation of the data which had been measured with several sorts of radiation the cybernetic model was applied. (orig./MG)

  11. Radiation response of floating gate EEPROM memory cells

    International Nuclear Information System (INIS)

    The effect of radiation on a floating gate EEPROM nonvolatile memory cell is determined experimentally and modeled analytically. The new model predicts the threshold voltage change resulting from radiation. A screen based on the initial 1 state (excess electron) threshold voltage is shown to be necessary to assure data retention during irradiation. Techniques to increase radiation hardness are also described. The hardness of floating gate cells is shown to be limited to less than 100 krad(Si) for a fixed reference sense amplifier. The use of a differential sense amplifier may increase this limit. Therefore, floating gate memories should be useful for those applications requiring low total-doses

  12. Development of bunchy top virus resistant banana cv lakatan in vitro culture and radiation technology

    International Nuclear Information System (INIS)

    Bunchy to virus (BTV) is the most destructive virus disease of banana in the Philippines. Incorporation of resistance to this virus disease by conventional hybridization is not possible due to male and female sterility of most commercial banana cultivars. In vitro culture coupled with radiation technology can be used to develop BTV resistance in banana cv. Lakatan. The sensitivity of banana shot tip explants to gamma irradiation was determined by subjecting the shoot tips to varying doses (5, 10, 20, 25, 30, 40, 60, 80 and 100 Gy) of irradiation. The LD sub 50 for banana shoot tips determined by 50% reduction in growth and shoot proliferation, was observed to around 20-25 Gy. Bulk irradiation of shoot tip explants was conducted using 20-25 Gy. Irradiated cultures were multiplied for 3-5 cycles and plants regenerated were potted out and screened for BTV resistance. A total of 3,447 irradiated plants regenerated from the radiosensitivity experiment (1,847 plants) and bulk irradiation of 20/25 Gy (1,600 plants) were screened for BTV resistance in the greenhouse using artificial BTV inoculation using the aphid vector Pentalonia nigronervosa. One hundred eighteen plants or 3.4% (118/3,447) of the artificially irradiated plants showed seedling resistance after 4-7 months of evaluation. These plants were planted in the field and were subjected to natural BTV infection. To date, 85 (out of the 118) putative seedling resistant plants continuously expressed BTV resistance in the field after more than 10 months of evaluation. The absence of BTV infection in 39 putative resistant plants was confirmed by ELISA test. Suckers from selected putative resistance plants will be collected, propagated and evaluated for the second cycle stability of BTV resistance and detailed characterization of important horticultural traits

  13. In vitro induction of variability through radiation for late blight resistance and heat tolerance in potato

    International Nuclear Information System (INIS)

    In vitro cultured shoots of potato, cvs. 'Kufri Jyoti' and 'Kufri Chandramukhi', were irradiated with 20 and 40 Gy gamma rays. Microtubers, obtained from MIV3 shoots multiplied in vitro, were planted in pots. The resulting plants were screened for resistance to late blight, using detached leaf method. In 'Kufri Chandramukhi', 42% plants and in 'Kufri Jyoti' 36% plants, obtained from 40 Gy treatment, showed resistance to late blight. The frequency of resistant plants was lower from 20 Gy treatment. The progenies of putatively resistant plants were grown in field, and inoculated with sporangial inoculum of late blight fungus. The field grown progeny segregated for disease resistance, and approximately 56% plants showed resistance. During the next propagation, the frequency of resistant plants increased to 72%. For developing heat tolerance, microtubers obtained from 20 and 40 Gy treatments and in vitro multiplied M1V3 shoots were cultured at high temperature of 28C. In both varieties, the number of the microtubers per plant was highly reduced and the resulting microtubers had distorted shape but showed better germination (62%), even in early sowing at relatively higher temperature. Of the two radiation doses, the higher dose of 40 Gy gave better results in both the varieties. Heat tolerance was also assessed from chlorophyll persistence. The progenies from putative heat-tolerant plants were tested in field by planting at higher temperature in two subsequent generations. The heat tolerant plants segregated in each generation, but the frequency of heat-tolerant plants increased. (author)

  14. The concept of radiation-enhanced stem cell differentiation

    Directory of Open Access Journals (Sweden)

    Mieloch Adam A.

    2015-09-01

    Full Text Available Background. Efficient stem cell differentiation is considered to be the holy grail of regenerative medicine. Pursuing the most productive method of directed differentiation has been the subject of numerous studies, resulting in the development of many effective protocols. However, the necessity for further improvement in differentiation efficiency remains. This review contains a description of molecular processes underlying the response of stem cells to ionizing radiation, indicating its potential application in differentiation procedures. In the first part, the radiation-induced damage response in various types of stem cells is described. Second, the role of the p53 protein in embryonic and adult stem cells is highlighted. Last, the hypothesis on the mitochondrial involvement in stem cell development including its response to ionizing radiation is presented.

  15. Mathematical Modeling of Contact Resistance in Silicon Photovoltaic Cells

    KAUST Repository

    Black, J. P.

    2013-10-22

    In screen-printed silicon-crystalline solar cells, the contact resistance of a thin interfacial glass layer between the silicon and the silver electrode plays a limiting role for electron transport. We analyze a simple model for electron transport across this layer, based on the driftdiffusion equations. We utilize the size of the current/Debye length to conduct asymptotic techniques to simplify the model; we solve the model numerically to find that the effective contact resistance may be a monotonic increasing, monotonic decreasing, or nonmonotonic function of the electron flux, depending on the values of the physical parameters. © 2013 Society for Industrial and Applied Mathematics.

  16. Determination of the Antibiotic Resistance Profile of Student Cell Phones

    Directory of Open Access Journals (Sweden)

    Lisa Ann Blankinship

    2012-08-01

    Full Text Available Sampling of common use items (e.g., student cell phones for bacterial presence, identification, and antibiotic resistance profiling helps students to recognize the need for routine cleaning of personal items and encourages thoughtful use of currently available medications. This multilab period project can be used to teach or reinforce several methods from general microbiology including aseptic technique, isolation streak, serial dilution, spread plating, Kirby Bauer testing, unknown identification, and media production. The data generated can be saved and added to each semester, thus providing a data set that reflects a local trend of antibiotic resistance.      

  17. Effects of ionizing radiation on differentiation of murine bone marrow cells into mast cells

    International Nuclear Information System (INIS)

    Mast cells, immune effector cells produced from bone marrow cells, play a major role in immunoglobulin E–mediated allergic responses. Ionizing radiation affects the functions of mast cells, which are involved in radiation-induced tissue damage. However, whether ionizing radiation affects the differential induction of mast cells is unknown. Here we investigated whether bone marrow cells of X-irradiated mice differentiated into mast cells. To induce mast cells, bone marrow cells from X-irradiated and unirradiated mice were cultured in the presence of cytokines required for mast cell induction. Although irradiation at 0.5 Gy and 2 Gy decreased the number of bone marrow cells 1 day post-irradiation, the cultured bone marrow cells of X-irradiated and unirradiated mice both expressed mast cell–related cell-surface antigens. However, the percentage of mast cells in the irradiated group was lower than in the unirradiated group. Similar decreases in the percentage of mast cells induced in the presence of X-irradiation were observed 10 days post irradiation, although the number of bone marrow cells in irradiated mice had recovered by this time. Analysis of mast cell function showed that degranulation of mast cells after immunoglobulin E–mediated allergen recognition was significantly higher in the X-irradiated group compared with in the unirradiated group. In conclusion, bone marrow cells of X-irradiated mice differentiated into mast cells, but ionizing radiation affected the differentiation efficiency and function of mast cells. (author)

  18. EZH2 Protects Glioma Stem Cells from Radiation-Induced Cell Death in a MELK/FOXM1-Dependent Manner

    DEFF Research Database (Denmark)

    Kim, Sung-Hak; Joshi, Kaushal; Ezhilarasan, Ravesanker;

    2015-01-01

    repressive complex 2, EZH2, is targeted by the MELK-FOXM1 complex, which in turn promotes resistance to radiation in GSCs. Clinically, EZH2 and MELK are coexpressed in GBM and significantly induced in postirradiation recurrent tumors whose expression is inversely correlated with patient prognosis. Through a......Glioblastoma (GBM)-derived tumorigenic stem-like cells (GSCs) may play a key role in therapy resistance. Previously, we reported that the mitotic kinase MELK binds and phosphorylates the oncogenic transcription factor FOXM1 in GSCs. Here, we demonstrate that the catalytic subunit of Polycomb...... essential for GSC radioresistance and therefore raise the possibility that MELK-FOXM1-driven EZH2 signaling can serve as a therapeutic target in irradiation-resistant GBM tumors....

  19. An exonuclease I-sensitive DNA repair pathway in Deinococcus radiodurans: a major determinant of radiation resistance.

    Science.gov (United States)

    Misra, Hari S; Khairnar, Nivedita P; Kota, Swathi; Shrivastava, Smriti; Joshi, Vasudha P; Apte, Shree K

    2006-02-01

    Deinococcus radiodurans R1 recovering from acute dose of gamma radiation shows a biphasic mechanism of DNA double-strand break repair. The possible involvement of microsequence homology-dependent, or non-homologous end joining type mechanisms during initial period followed by RecA-dependent homologous recombination pathways has been suggested for the reconstruction of complete genomes in this microbe. We have exploited the known roles of exonuclease I in DNA recombination to elucidate the nature of recombination involved in DNA double-strand break repair during post-irradiation recovery of D. radiodurans. Transgenic Deinococcus cells expressing exonuclease I functions of Escherichia coli showed significant reduction in gamma radiation radioresistance, while the resistance to far-UV and hydrogen peroxide remained unaffected. The overexpression of E. coli exonuclease I in Deinococcus inhibited DNA double-strand break repair. Such cells exhibited normal post-irradiation expression kinetics of RecA, PprA and single-stranded DNA-binding proteins but lacked the divalent cation manganese [(Mn(II)]-dependent protection from gamma radiation. The results strongly suggest that 3' (rho) 5' single-stranded DNA ends constitute an important component in recombination pathway involved in DNA double-strand break repair and that absence of sbcB from deinococcal genome may significantly aid its extreme radioresistance phenotype. PMID:16430702

  20. Radiation-Induced Notch Signaling in Breast Cancer Stem Cells

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-01

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

  1. Radiation-Induced Notch Signaling in Breast Cancer Stem Cells

    International Nuclear Information System (INIS)

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

  2. Handling technique of spore-forming bacteria in radiation sterilization. 2. Determination of numbers and radiation resistance of spores

    International Nuclear Information System (INIS)

    Stepwise ten-fold dilution of bacterial solution is required in the determination of bacterial spores. For this, the selection of diluted solution is important according to the purpose of experiment. First, the preparation of suspension of bacterial spores and selection of diluted solution are presented. Then, a method for determining the number of bacterial spores in materials is outlined in terms of dilution methods of bacterial solution (shaking and homogenization) and application method of diluted solution to the plating medium. Finally, a method for determining radiation resistance of spore-forming bacteria is explained according to the measurement conditions (suspension of bacterial spores and filters applied with bacterial spores). (N.K.)

  3. Model of cell response to {\\alpha}-particle radiation

    CERN Document Server

    Liu, Longjian

    2012-01-01

    Starting from a general equation for organism (or cell system) growth and attributing additional cell death rate (besides the natural rate) to therapy, we derive an equation for cell response to {\\alpha} radiation. Different from previous models that are based on statistical theory, the present model connects the consequence of radiation with the growth process of a biosystem and each variable or parameter has meaning regarding the cell evolving process. We apply this equation to model the dose response for {\\alpha}-particle radiation. It interprets the results of both high and low linear energy transfer (LET) radiations. When LET is high, the additional death rate is a constant, which implies that the localized cells are damaged immediately and the additional death rate is proportional to the number of cells present. While at low LET, the additional death rate includes a constant term and a linear term of radiation dose, implying that the damage to some cell nuclei has a time accumulating effect. This model ...

  4. Increasing the radiation resistance of single-crystal silicon epitaxial layers

    Directory of Open Access Journals (Sweden)

    Kurmashev Sh. D.

    2014-12-01

    Full Text Available The authors investigate the possibility of increasing the radiation resistance of silicon epitaxial layers by creating radiation defects sinks in the form of dislocation networks of the density of 109—1012 m–2. Such networks are created before the epitaxial layer is applied on the front surface of the silicon substrate by its preliminary oxidation and subsequent etching of the oxide layer. The substrates were silicon wafers KEF-4.5 and KDB-10 with a diameter of about 40 mm, grown by the Czochralski method. Irradiation of the samples was carried out using electron linear accelerator "Electronics" (ЭЛУ-4. Energy of the particles was 2,3—3,0 MeV, radiation dose 1015—1020 m–2, electron beam current 2 mA/m2. It is shown that in structures containing dislocation networks, irradiation results in reduction of the reverse currents by 5—8 times and of the density of defects by 5—10 times, while the mobility of the charge carriers is increased by 1,2 times. Wafer yield for operation under radiation exposure, when the semiconductor structures are formed in the optimal mode, is increased by 7—10% compared to the structures without dislocation networks. The results obtained can be used in manufacturing technology for radiation-resistant integrated circuits (bipolar, CMOS, BiCMOS, etc..

  5. DNA repair and resistance to UV-B radiation in western spotted frogs

    Science.gov (United States)

    Blaustein, A.R.; Hays, J.B.; Hoffman, P.D.; Chivers, D.P.; Kiesecker, J.M.; Leonard, W.P.; Marco, A.; Olson, D.H.; Reaser, J.K.; Anthony, R.G.

    1999-01-01

    We assessed DNA repair and resistance to solar radiation in eggs of members of the western spotted frog complex (Rana pretiosa and R. luteiventris), species whose populations are suffering severe range reductions and declines. Specifically, we measured the activity of photoreactivating enzyme (photolyase) in oocytes of spotted frogs. In some species, photoreactivation is the most important mechanism for repair of UV-damaged DNA. Using field experiments, we also compared the hatching success of spotted frog embryos at natural oviposition sites at three elevations, where some embryos were subjected to ambient levels of UV-B radiation and others were shielded from UV-B radiation. Compared with other amphibians, photolyase activities in spotted frogs were relatively high. At all sites, hatching success was unaffected by UV-B. Our data support the interpretation that amphibian embryos with relatively high levels of photolyase are more resistant to UV-B radiation than those with lower levels of photolyase. At the embryonic stage, UV-B radiation does not presently seem to be contributing to the population declines of spotted frogs.

  6. Classical Radiation Reaction in Particle-In-Cell Simulations

    CERN Document Server

    Vranic, Marija; Fonseca, Ricardo A; Silva, Luis O

    2015-01-01

    Under the presence of ultra high intensity lasers or other intense electromagnetic fields the motion of particles in the ultrarelativistic regime can be severely affected by radiation reaction. The standard particle-in-cell (PIC) algorithms do not include radiation reaction effects. Even though this is a well known mechanism, there is not yet a definite algorithm nor a standard technique to include radiation reaction in PIC codes. We have compared several models for the calculation of the radiation reaction force, with the goal of implementing an algorithm for classical radiation reaction in the Osiris framework, a state-of-the-art PIC code. The results of the different models are compared with standard analytical results, and the relevance/advantages of each model are discussed. Numerical issues relevant to PIC codes such as resolution requirements, application of radiation reaction to macro particles and computational cost are also addressed. The Landau and Lifshitz reduced model is chosen for implementatio...

  7. Radiation resistance of epoxy systems: I. Effect of epoxy resin structure

    International Nuclear Information System (INIS)

    A series of epoxy resins have been formulated for use at cryogenic temperatures and more specifically for superconducting magnets. The radiation resistance of these materials will be critical for some applications and thus the purpose of this report is to describe the thermal, physical and mechanical properties of a series of epoxy formulations as a function of total radiation dose using a 60C source. The properties are measured both at cryogenic and ambient conditions. A diglycidyl ether of bisphenol A monomer is coreacted with a series of aliphatic diamines and contrasted with the same formulation using the diglycidyl ester of hexahydrophthalic anhydride

  8. Cyrogenic and radiation resistant properties of three dimensional fabric reinforced composite materials

    International Nuclear Information System (INIS)

    The insulating and/or structural materials for the fusion superconducting magnets are used under such strict environments as the cryogenic temperatures, high stresses and radiation environments. It is recognized that the usual laminated composite materials reinforced by glass clothes (2D-GFRP) are difficult to be used in such strict conditions. The three dimensional glass fabric reinforced composite materials (3D-GFRP) have high interlaminar shear strength due to the fibers in thickness direction. The cryogenic and radiation resistance properties of 3D-GFRP had been measured and the results compared with those of the 2D-GFRP

  9. Rituximab enhances radiation-triggered apoptosis in non-Hodgkin's lymphoma cells via caspase-dependent and - independent mechanisms

    International Nuclear Information System (INIS)

    Rituximab (RTX), a chimeric human anti-CD20 monoclonal antibody, is currently employed in the treatment of malignant non-Hodgkin's lymphoma (NHL) either alone or in combination with other cytotoxic approaches. The present study examines the effects of ionizing radiation in combination with RTX on proliferation and apoptosis development in B-lymphoma RL and Raji cells. RTX was used at a concentration of 10 μg/mL 24 hours prior to irradiation at a single dose of 9 Gy. CD20 expression, cell viability, apoptosis, mitochondrial membrane potential and apoptosis-related proteins were evaluated in the treated B cells. The constitutive level of CD20 expression in RL and Raji lymphoma cells did not play an essential role in RTX-induced cell growth delay. Both lymphoma cells showed similar inhibition of cell proliferation without apoptosis development in response to RTX treatment. Exposure to ionizing radiation induced cell growth delay and apoptosis in RL cells, whereas Raji cells showed moderate radio-resistance and activation of cell growth at 24 hours after irradiation, which was accompanied by increased radiation-triggered CD20 expression. The simultaneous exposure of lymphoma cells to ionizing radiation and RTX abrogated radioresistance of Raji cells and significantly enhanced cell growth delay and apoptosis in RL cells. X-linked inhibitor of apoptosis protein (XIAP) and the inducible form of heat shock protein 70 (Hsp70) were positively modulated by RTX in combination with ionizing radiation in order to induce apoptosis. Furthermore, it was demonstrated that mitochondrial membrane potential dissipation is not an essential component to induce apoptosis-inducing factor (AIF) maturation and apoptosis. Our results show that RTX-triggered enhancement of radiation-induced apoptosis and cell growth delay is achieved by modulation of proteins involved in programmed cell death. (author)

  10. Radiation related basic cancer research : research for radiation induced tumor cell killing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Hoon; Hong, Seok Il; Cho, Kyung Ja; Kim, Byung Gi; Lee, Kee Ho; Nam, Myung Jin

    1999-04-01

    The radioresistant clones was established from human U251 glioblastoma cell line through intermittently exposed to 3 Gy gamma-radiation for six months. Treatment of SNU-16 cells with various doses of radiation, TNF alpha and PMA resulted in a decrease in cell viability. The results prove that cell death of SNU16 is a apoptosis mediated by caspase-3. We have examined the expression of bcl-2 and c-myc in cervical cancer specimens and cervical intraepithelial neoplasia (CIN) to determine the role of coexpression of bcl-3 and c-myc during progression into cervical cancer. The frequent alterations in FHIT expression in many cervical carcinomas and their cell lines suggest that FHIT gene alterations are pla a role in cervical tumorigenesis. According to these correlation between the viability and apoptosis of RD cells, the proper range of the dosage for the investigation of differentiation potency in RD cells was assessed as 1 to 3Gy.