Dissertations / Theses on the topic 'Radiation induced bystander effect'
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Liu, Chang S. B. Massachusetts Institute of Technology. "Radiation-induced bystander fibroblasts both reduce and amplify micronuclei induction through the reciprocal bystander effect and the secondary bystander effect." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106695.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 25-27).
Aside from directly causing DNA damage, the traversal of radiation through cells also induces the bystander effect, which is the biological response of unirradiated cells that are neighboring or sharing medium with the irradiated cells. Although the mechanisms through which irradiated cells send signals to the bystander cells are not well understood, the bystander effect could potentially have clinical relevance or play a significant role in low dose radiation environments. The research in this thesis focuses on the ability of the bystander cells to influence the behavior of cells that share medium with them, which can be separated into three categories: unirradiated cells, irradiated cells, and the original irradiated cells that caused the bystander effect. These can be considered the "secondary bystanders." Human AG01522 fibroblasts were irradiated with 250 kVp X-rays and co-cultured with unirradiated fibroblasts to generate bystander cells, which were then cocultured with one of the three types of secondary bystander cells. The micronucleus assay was used to analyze the amount of chromosome aberrations present. In the unirradiated secondary bystander population, an increase in percentage of binucleated cells with micronuclei from the background level to approximately the level of the primary bystander cells was observed, indicating that bystander cells can send damaging signals. The data also showed that there was a lower frequency of micronuclei formation in the irradiated population with bystander inserts in comparison to irradiated populations without bystanders. However, there were no conclusive data on the effect of the bystander cells on other irradiated cells. Overall, the results suggest that bystander fibroblasts are capable of sending both detrimental and beneficial signals and can induce a range of behaviors in other cells.
by Chang Liu.
S.B.
Koturbash, Igor, and University of Lethbridge Faculty of Arts and Science. "Molecular mechanisms of radiation-induced bystander effects in vivo." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2008, 2008. http://hdl.handle.net/10133/664.
Full textxiii, 208 leaves : ill. ; 29 cm.
Gonon, Géraldine. "Space radiation-induced bystander effect : kinetics of biologic responses, mechanisms, and significance of secondary radiations." Phd thesis, Université de Franche-Comté, 2011. http://tel.archives-ouvertes.fr/tel-00987717.
Full textWhiteside, James Roy. "Persistent genomic instability and bystander effects induced by ultraviolet radiation." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444640.
Full textAnzenberg, Vered. "LET dependence of radiation-induced bystander effects using human prostate tumor cells." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44795.
Full text"June 2008."
Includes bibliographical references (leaves 133-140).
In the past fifteen years, evidence provided by many independent research groups have indicated higher numbers of cells exhibiting damage than expected based on the number of cells traversed by the radiation. This phenomenon has been coined as the "bystander effect". The purpose of this study was to characterize the ability of irradiated tumor cells to induce bystander effects in co-cultured cells. Human DU-145 prostate carcinoma cells were grown on a 1.4 [mu]m-thick mylar membrane in specially constructed cell culture dishes for irradiation with alpha particles (average energy 3.14 MeV) from a 241Am source, or in 6-well plates for irradiation with 250 kVp x-rays at 25°C. In parallel experiments, the tumor cells were incubated at 4°C for one hour prior to irradiation and irradiated on ice to test the nature of the bystander signal. Bystander cells were placed into the medium above the irradiated DU-145 and were co-incubated for a length of time. The bystander effect endpoints measured in either DU-145 tumor cells or in normal primary AGO1522 fibroblasts were micronucleus (MN) formation, [gamma]-H2AX double strand break repair foci, and survival fraction. A 1.5-2.0-fold increase in MN formation was observed in both DU-145 and AG01522 bystander cells after either alpha particle or xray irradiation of the DU-145 target cells. A 1.5-fold [gamma]-H2AX bystander increase and a survival fraction reduction to 80% were only detected in AGO1522 cells, and only after xray irradiation of target DU-145 cells. Alpha particle irradiation of the target DU-145 cells produced neither [gamma]-H2AX foci nor survival fraction bystander effect in either cell line. Lowering the temperature to 4°C during the irradiation of the DU-145 tumor cells, with either x-rays or alpha particles, eliminated both the MN formation and the decreased survival fraction bystander effects in the co-cultured AG01522 fibroblasts.
(cont.) This study demonstrates that biochemical processes in the directly-irradiated tumor cells are required for initiation of the signaling process. Low temperature during the irradiation inhibited the initiation of a bystander signal. There are also LET-dependent differences in the signal released from DU-145 human prostate carcinoma cells; and that, for some endpoints, bystander AG01522 fibroblasts and bystander DU-145 prostate carcinoma cells respond differently to the same, medium-mediated signal.
by Vered Anzenberg.
Ph.D.
Blyth, Benjamin John, and benjamin blyth@flinders edu au. "Development and use of an adoptive transfer method for detecting radiation-induced bystander effects in vivo." Flinders University. School of Medicine, 2009. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20091008.150317.
Full textFullerton, Natasha Eileen. "Gene therapy and targeted radiotherapy applied to bladder and prostate cancer : examination of radiation-induced bystander effects in targeted radiotherapy." Thesis, University of Glasgow, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438687.
Full textWordsworth, James William. "The senescent cell induced bystander effect." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2536.
Full textZemp, Franz Joseph, and University of Lethbridge Faculty of Arts and Science. "The bystander effect : animal and plant models." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2008, 2008. http://hdl.handle.net/10133/685.
Full textxiv, 141 p. : ill. ; 29 cm.
Lumpkins, Sarah B. "Space radiation-induced bystander signaling in 2D and 3D skin tissue models." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70817.
Full textPage 157 blank. Cataloged from PDF version of thesis.
Includes bibliographical references (p. 145-156).
Space radiation poses a significant hazard to astronauts on long-duration missions, and the low fluences of charged particles characteristic of this field suggest that bystander effects, the phenomenon in which a greater number of cells exhibit damage than expected based on the number of cells traversed by radiation, could be significant contributors to overall cell damage. The purpose of this thesis was to investigate bystander effects due to signaling between different cell types cultured within 2D and 3D tissue architectures. 2D bystander signaling was investigated using a transwell insert system in which normal human fibroblasts (A) and keratinocytes (K) were irradiated with 1 GeV/n protons or iron ions at the NASA Space Radiation Laboratory using doses from either 2 Gy (protons) or 1 Gy (iron ions) down to spacerelevant low fluences. Medium-mediated bystander responses were investigated using three cell signaling combinations. Bystander signaling was also investigated in a 3D model by developing tissue constructs consisting of fibroblasts embedded in a collagen matrix with a keratinocyte epidermal layer. Bystander experiments were conducted by splitting each construct in half and exposing half to radiation then placing the other half in direct contact with the irradiated tissue on a transwell insert. Cell damage was evaluated primarily as formation of foci of the DNA repair-related protein 53BP1. In the 2D system, both protons and iron ions yielded a strong dose dependence for the induction of 53BP1 in irradiated cells, while the magnitudes and time courses of bystander responses were dependent on radiation quality. Furthermore, bystander effects were present in all three cell signaling combinations even at the low proton particle fluences used, suggesting the potential importance of including these effects in cancer risk models for low-dose space radiation exposures. Cells cultured in the 3D constructs exhibited a significant reduction in the percentages of both direct and bystander cells positive for 53BP1 foci, although the qualitative kinetics of DNA damage and repair were similar to those observed in 2D. These results provide evidence that the microenvironment significantly influences intercellular signaling and that cells may be more radioresistant in 3D compared to 2D systems.
by Sarah B. Lumpkins.
Sc.D.
Nishiura, Hideki. "The bystander effect is a novel mechanism of UVA-induced melanogenesis." Kyoto University, 2012. http://hdl.handle.net/2433/157451.
Full textDiegeler, Sebastian [Verfasser]. "The role of nuclear factor kappa B in the radiation-induced bystander response / Sebastian Diegeler." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1219904465/34.
Full textMacPhail, Susan Helen. "Effect of intercellular contact on radiation-induced DNA damage." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27986.
Full textMedicine, Faculty of
Pathology and Laboratory Medicine, Department of
Graduate
Barbara, Nabil Victor 1964. "Simulation of radiation-induced parametric degradation in electronic amplifiers." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277143.
Full textMorabito, Brian Joseph. "Quantitating radiation induced DNA breaks by capillary electrophoresis." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/16339.
Full textGladney, Dewey Clinton. "Simulating radiation-induced defects on semiconductor devices." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FGladney.pdf.
Full textAlvarado, Chacón Fresia. "Ion induced radiation damage on the molecular level." [S.l. : Groningen : s.n. ; University Library of Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/305192396.
Full textTamminga, Jan, and University of Lethbridge Faculty of Arts and Science. "Radiation-induced epigenome deregulation in the male germline." Thesis, Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2008, 2008. http://hdl.handle.net/10133/746.
Full textxii, 121 leaves : ill. ; 29 cm.
Rafferty, Teresa S. "The effect of selenium on ultraviolet-B radiation-induced damage to the skin." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/22570.
Full textSafarjameh, Kourosh 1961. "Fast-neutron-induced resistivity change in power MOSFETs." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277011.
Full textFengler, John Josef Paul. "Respiration induced oxygen gradients in cultured mammalian cells." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28381.
Full textScience, Faculty of
Physics and Astronomy, Department of
Graduate
Coombs, Anne-Marie. "A study of near-ultraviolet radiation induced oxidative damage in Escherichia coli." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380929.
Full textBryer, Bevan. "Protection unit for radiation induced errors in flash memory systems." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50070.
Full textENGLISH ABSTRACT: Flash memory and the errors induced in it by radiation were studied. A test board was then designed and developed as well as a radiation test program. The system was irradiated. This gave successful results, which confirmed aspects of the study and gave valuable insight into flash memory behaviour. To date, the board is still being used to test various flash devices for radiation-harsh environments. A memory protection unit (MPU) was conceptually designed and developed to morntor flash devices, increasing their reliability in radiation-harsh environments. This unit was designed for intended use onboard a micro-satellite. The chosen flash device for this study was the K9F1208XOA model from SAMSUNG. The MPU was designed to detect, maintain, mitigate and report radiation induced errors in this flash device. Most of the design was implemented in field programmable gate arrays and was realised using VHDL. Simulations were performed to verify the functionality of the design subsystems. These simulations showed that the various emulated errors were handled successfully by the MPU. A modular design methodology was followed, therefore allowing the chosen flash device to be replaced with any flash device, following a small reconfiguration. This also allows parts of the system to be duplicated to protect more than one device.
AFRIKAANSE OPSOMMING: 'n Studie is gemaak van" Flash" geheue en die foute daarop wat deur radiasie veroorsaak word. 'n Toetsbord is ontwerp en ontwikkel asook 'n radiasie toetsprogram waarna die stelsel bestraal is. Die resultate was suksesvol en het aspekte van die studie bevestig en belangrike insig gegee ten opsigte van "flash" komponente in radiasie intensiewe omgewmgs. 'n Geheue Beskermings Eenheid (GBE) is konseptueel ontwerp en ontwikkelom die "flash" komponente te monitor. Dit verhoog die betroubaarheid in radiasie intensiewe omgewings. Die eenheid was ontwerp met die oog om dit aan boord 'n mikro-satelliet te gebruik. Die gekose "flash" komponent vir die studie was die K9F1208XOA model van SAMSUNG. Die GBE is ontwerp om foute wat deur radiasie geïnduseer word in die "flash" komponent te identifiseer, herstel en reg te maak. Die grootste deel van die implementasie is gedoen in "field programmable gate arrays" and is gerealiseer deur gebruik te maak van VHDL. Simulasies is gedoen om die funksionaliteit van die ontwikkelde substelsels te verifieer. Hierdie simulasies het getoon dat die verskeie geëmuleerde foute suksesvol deur die GBE hanteer is. 'n Modulre ontwerpsmetodologie is gevolg sodat die gekose "flash" komponent deur enige ander flash komponent vervang kan word na gelang van 'n eenvoudige herkonfigurasie. Dit stelook dele van die sisteem in staat om gedupliseer te word om sodoende meer as een komponent te beskerm.
Kovach, Matthew James. "Adaptive Advantages of Carotenoid Pigments in Alpine and Subalpine Copepod Responses to Polycyclic Aromatic Hydrocarbon Induced Phototoxicity." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc28444/.
Full textByrne, Shaun Edward. "An investigation into the processing of ionising radiation induced clustered DNA damage sites using mammalian cell extracts." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.670082.
Full textNilsson, Kenneth. "Radiation induced pneumonitis : clinical and experimental studies with special emphasis on the effect of smoking." Doctoral thesis, Umeå universitet, Onkologi, 1992. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-100545.
Full textDiss. (sammanfattning) Umeå : Umeå universitet, 1992, härtill 5 uppsatser.
digitalisering@umu
Lin, Jun. "Radiation-induced alterations in mesoporous silicas : The effect of electronic processes involving ions and electrons." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2022. http://theses.enscm.fr/ENSCM_2022_LIN.pdf.
Full textMaterials used in nuclear energy (fuel, packaging matrix, structural materials...) are subject to significant stresses due to the creation of defects that modify their properties. Several studies have shown that interfaces can act as a sink for defects caused by irradiation, which suggests that nanomaterials could have a higher resistance to irradiation than materials with a "micrometric" structure. Simultaneously, mesoporous silica materials have grown in popularity in recent years and are becoming more involved in the domain related to radiation conditioning, such as the prospective use of conditioning for nuclear waste. While research has begun to focus on the behavior of non-porous silica materials when exposed to radiation, no extensive investigations have been conducted on the behavior of mesoporous silica when exposed to radiation, particularly at electronic irradiation regime.This thesis aims to comprehend and explain the radiation-induced changes in mesoporous silicas under electronic regimes. This work quantified the evolution of physical (pore volume, pore diameter and distribution...) and structural (polymerization of the network, creation of defects...) properties of mesoporous silica irradiated with high-energy ion beams with stopping powers ranging from 1 keV/nm to 12 keV/nm, and with electron beams (10 - 300 keV and 0.6 - 2.4 MeV). Post-irradiation characterization methods (X-ray reflectivity, gas adsorption, SAXS, FTIR, etc.) have been used, as well as in-situ pore structure monitoring using electron microscopes. The experimental findings indicated that pore structures were susceptible to a certain degree of irradiation-induced shrinking. In contrast, evidence shows that the silica network itself does not alter much in porous silica compared to non-porous silica. Meanwhile, a 3DTS (3D thermal spike) model has been successfully applied to describe and explain the observed pore contraction behavior in response to ionic irradiation. Additionally, the mechanism of pore contraction under electron irradiation has been delineated according to the domain of incident electron energies. When compared to non-porous silica, this research has demonstrated that the existence of nanoscale pores reduces the accumulation of damage induced by irradiation. In conjunction with this effect, the pore contracts until it completely disappears under the impact of irradiation. This characteristic could, from an applicative point of view, be of interest to practitioners in the context of new methods of treating radioactive effluents, such as through the use of a "separation/conditioning" strategy, or in the context of the self-healing of porous gel layers formed on the surface of vitrified waste packages whose final destination is deep geological disposal
McRae, Dorothy A., and University of Lethbridge Faculty of Arts and Science. "Radiation induced epigenetic dysregulation in rat mammary gland tissue / Dorothy A. McRae." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences, c2010, 2010. http://hdl.handle.net/10133/2615.
Full textxi, 120 leaves ; 29 cm
Merrifield, Matthew, and University of Lethbridge Faculty of Arts and Science. "Radiation-induced deregulation of PiRNA pathway proteins : a possible molecular mechanism underlying transgenerational epigenomic instability." Thesis, Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Science, c2011, 2011. http://hdl.handle.net/10133/2617.
Full textix, 123 leaves : ill. (some col.) ; 29 cm
Cai, Linghui, and 蔡凌辉. "Monte Carlo simulation of positron induced secondary electrons in thincarbon foils." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45460863.
Full textBarreiro, Fidalgo Alexandre. "Experimental studies of radiation-induced dissolution of UO2 : The effect of intrinsic solid phase properties and external factors." Doctoral thesis, KTH, Tillämpad fysikalisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205605.
Full textQC 20170421
Martius, Gesa [Verfasser], Giuliano [Akademischer Betreuer] Ramadori, Wolfgang [Akademischer Betreuer] Engel, and Wilfried [Akademischer Betreuer] Kramer. "Effect of radiation on hepatic fat metabolism in rat and mouse: A role of radiation-induced TNF-α in the regulation of FAT/CD36 / Gesa Martius. Gutachter: Wolfgang Engel ; Wilfried Kramer. Betreuer: Giuliano Ramadori." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1075372909/34.
Full textMedhat, Abdel Maksoud Dina. "Study of New Miniaturized Microwave Devices based on Ratchet Effect in an Environment of Asymmetric Nano-Scatterers." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0075/document.
Full textNanotechnology is a growing field that has attracted significant research attention due to its unlimited potential applications. Millimeter wave technology is another interesting field that plays a leading role in the development of wireless communications systems. Combining these two advanced research fields together, has given rise to the innovation of the Ratchet Device which is now a new challenging application. This device has a nanoscale size and its concept of operation consists of generating a DC voltage when radiating a two-dimensional electron gas based device with microwave energy. The aim of this thesis is in trying to improve the device response and hence opening new perspectives in the fabrication of high frequency field detectors on the nanoscale level. Unfortunately, the current Ratchet Devices, based on semiconductor heterostructures, realized till now, operate at low temperatures to ensure high electron mobility. This condition necessitates the use of a complex experimental setup that has a great impact on the induced voltage and on the reproducibility of the observed Ratchet phenomenon. In this context, the work performed within the framework of this thesis has addressed this problem in two parts. The first part concerns the electromagnetic analysis of the experimental setup behavior. This has been achieved by implementing intensive full wave electromagnetic simulations. Different solutions have been proposed to optimize the setup and thus enhance the Ratchet voltage produced. In addition to the electromagnetic study, some modulation measurements have been performed to test the feasibility of the Ratchet Device as an amplitude demodulator. The second part of this thesis deals with the study of the material composing the Ratchet Device. Recently, graphene has started to invade the scientific and the technological world with its fascinating electronic properties, such as its high electron mobility at room temperature, which distinguishes it from conventional materials that typically collide with obstacles. As a result, the idea of fabricating a Ratchet Device based on graphene instead of semiconductor heterojunctions has been introduced. Several design models, characterizations and RF measurements have been performed in order to obtain a reliable Ratchet Device suitable for many practical applications at room temperature. This has been done in the microwave frequency range and can also extend to the terahertz band
Popel, Aleksej. "The effect of radiation damage by fission fragments on the structural stability and dissolution of the UO2 fuel matrix." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/265103.
Full textMansour, Nastaran. "Nonlinear Absorption Initiated Laser-Induced Damage in [Gamma]-Irradiated Fused Silica, Fluorozirconate Glass and Cubic Zirconia." Thesis, University of North Texas, 1988. https://digital.library.unt.edu/ark:/67531/metadc331327/.
Full textJin, Xin. "Combining RBS/Channeling, X-ray diffraction and atomic-scale modelling to study irradiation-induced defects and microstructural changes." Thesis, Limoges, 2021. http://www.theses.fr/2021LIMO0017.
Full textEnergetic particles are involved in many activities of modern society. They constitute a significant aspect of the semiconductor industry and may play important role in shaping materials in a controllable way in the future. However, their energetic nature also poses grand challenges, especially in the nuclear industry. Thus, it is crucial to have a comprehensive understanding of the underlying mechanisms of irradiation-induced defects and the associated microstructural changes. Experimentally, irradiation-induced effects can be monitored by characterization techniques including, but not limited to, Rutherford backscattering spectrometry in channeling mode (RBS/C) and X-ray diffraction (XRD), because they are extremely sensitive to changes in the crystalline structure. However, it is not straightforward to establish a clear link between the characterization results and the defect quantity and nature, and this connection is usually made according to simple phenomenological models. In this thesis work, in order to cope with this problem, we performed RBS/C and XRD atomic-scale modelling. The first step was to improve a recently developed RBS/C simulation code that can generate RBS/C signals from arbitrary atomic structures. By modifying the algorithms describing ion-solid interactions and adding new features, we enhanced the flexibility of the code and its applicability to different types of materials. Subsequently, we employed the improved RBS/C code with a XRD program to compute disordering and elastic strain kinetics of a model material, namely UO2, as a function of irradiation fluence. Radiation defects in UO2 were simulated by molecular dynamics (MD) calculations. Both the strain and disordering kinetics exhibit qualitatively close agreement with those determined experimentally, indicating the validity of the used methodology. The decomposition of the kinetics was performed in order to study the effect of each defect separately, which enables a quantitative description of the disordering and strain build-up processes. Finally, we computed RBS/C and XRD signals from Fe MD cells, each of which contains one single type of defects. A clear comparison of disorder and elastic strain induced by different types of defects in Fe was made. The relation between RBS/C yield and He energy was also studied using the Fe MD cells, which shows dependency with defect types. The global approach used in this work has the hope to be extended and tested in more materials
Filho, Rinaldo Gregório. "Condutividade induzida por radiação ionizante no Mylar (PET) e Kapton (polimiidia)." Universidade de São Paulo, 1986. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-10022010-144145/.
Full textIn this work we present extensive results of measurements of the prompt and delayed radiation-induced conductivity of samples of PET and Kapton. Experimental parameters, such as the effective energy of the radiation, the exposure rate, the total dose, the value of the applied electric field, the nature of the electrodes, and the ambienta1 conditions were changed within wide limits. We also report measurement of thermally stimulated currents for non-irradiated and for irradiated samples which allowed us to investigate the trap-structure of the materials. Measurements of photo-Compton currents with different electrode materials and sample thicknesses gave information about the relation between the nature of the electrodes and the amplitudes of the currents. Based on the generalized rate theory of radiation-induced conduction we developed a theoretical model which includes the effect of the applied electric field on the carrier generation yield (geminate recombination, Onsager effect). Comparison of experimental and theoretical curves allowed us to determine the values of the main conduction parameters, such as carrier mobility, recombination coefficient, trap densities, for the materials under investigation.
Sjostedt, Svetlana. "An in vitro investigation of the impact of radiation induced bystander effect on the therapeutic irradiation of a prostate cancer cell line." Thesis, 2013. http://hdl.handle.net/2440/81550.
Full textThesis (M.Sc.(Med.Phy.)) -- University of Adelaide, School of Chemistry and Physics, 2013
Hou, Ya-Hsiue, and 侯雅雪. "Radiation-Induced Bystander Effect in Human Glioblastoma Cells and Functional Characterization of Lung Cancer Related Genes." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/u6prap.
Full text中臺科技大學
放射科學研究所
96
Lung cancer, especially non-small cell lung cancer (NSCLC), is the most common cause of cancer related death worldwide. It is generally believed that lack of biomarkers of early detection or prognosis of NSCLC is the main reason that explains high mortality of this disease. In order to obtain such biomarkers, we have conducted a lung cancer cell line-based functional genomics screen, in which sox9 was a candidate biomarker. In the present study, in silico data mining and molecular biology emphasizing siRNA gene silencing technique was used to probe the functional roles of sox9 in NSCLC. Here we showed that the expression of sox9 is significantly higher in the tumor parts than in the normal parts of cells of NSCLC; mean while, its expression is also higher in patients with recurrent diseases than those without. Furthermore, silencing of sox9 expression can cause reduced viability of cells, affect the cell cycle progression through G1 or G2 phases, and change the invasion capability of cells. Microarray gene expression analysis and quantitative polymerase chain reaction (q-PCR) revealed that the genes affected by silencing of sox9 included MT2A、FTL、CASP4、FTH1、RPL35、AKAP5、JNK1 (up-regulated) and sox1、sox17、BBC3、IRS2、WNT6 (down-regulated). Many of the differentially expressed genes are involved in the signaling pathways of cell growth or proliferation. In summary, we concluded that sox9 plays important roles in the survival of NSCLC cells.
Lo, Chia-Chien, and 羅佳茜. "Low dose radiation induces cellular senescence and bystander effect associated metastasis phenomenon by up-regulation of c-Myc and cofilin-1." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/50575683509244812863.
Full text國立陽明大學
生物醫學影像暨放射科學系
101
The low dose radiation may induce cellular senescence and promote secondary maligancy during radiotherapy. However, the molecular mechanisms are unclear. It has been reported that a variety of early response oncogenes can be up-regulated by the low dose radiation. Because oncogene-induced senescence (OIS) has been considered important for tumor development, we are interested in investigating whether the sublethal dose radiation also raises OIS to affect the malignancy. To this end, human diploid fibroblasts WI-38 cells and human non-small lung cancer H1299 cells were exposed to less than 2Gy of X-rays delivered by the RS2000 X-rays machine. Both cell types exhibited senescent phenotypes within a dose-dependent manner using the senescence-associated β-galactosidase (SA-β-gal) staining. Subsequently, we investigated the expression of c-Myc and k-Ras oncogenes, and the results showed that low dose radiation could induce c-Myc, but not k-Ras, in both transcriptional and translational levels. Additionally, up-regulated c-Myc exhibited transcriptional activity as demonstrated by the promoter-based reporter gene assys. Although the low dose radiation caused cellular senescence in exposed cells, the collected culture medium could increase the motility of non-irradiated H1299 cancer cells using the wound healing assay. Furthermore, the low dose radiation induced senescent phenotype was suppressed in cells treated with siRNA against c-Myc. Meanwhile, the motility of non-irradiated cells was not increased by the cultured medium obtained from irradiated c-Myc silenced cells. Taken together, the current data suggest that the low dose radiation causes c-Myc oncogene induced senescence, and this event may promote the bystander effects that influence the motility of non-irradiated cancer cells. In view of cMyc gene used some medicine to suppress the above phenomenon, and increased tumor control rate.
Feng, Shaoyong. "C. Elegans and Microbeam Models in Bystander Effect Research." Thesis, 2013. http://hdl.handle.net/1969.1/151271.
Full textSilva, Ana Manuela dos Santos. "The protective effect of regucalcin against radiation-induced testicular damage." Master's thesis, 2015. http://hdl.handle.net/10400.6/6061.
Full textO cancro testicular é a malignidade masculina mais frequente nos jovens, e a radioterapia é normalmente usada no seu tratamento. No entanto, a exposição à radiação tem vários efeitos secundários na fertilidade masculina, tornando-se necessária a identificação de estratégias efectivas para a proteger do dano testicular provocado pela radioterapia. A regucalcina (RGN) é uma proteína de ligação ao cálcio (Ca2+) que se encontra amplamente expressa no tracto reprodutor masculino. Vários estudos demonstraram a capacidade supressora da RGN na morte celular de diferentes tipos de células. Anteriormente, o nosso grupo de investigação mostrou que a sobre-expressão de RGN teve efeitos benéficos na espermatogénese por suprimir a apoptose induzida quimicamente. Para além disso, a RGN é regulada positivamente em linhas celulares radiorresistentes, sugerindo que esta pode proteger de danos causados pela radiação. O presente trabalho visa avaliar se a RGN desempenha um papel benéfico na recuperação da espermatogénese após radioterapia. Ratos, quer transgénicos que sobre-expressam a RGN (Tg-RGN) quer os seus homólogos selvagens (Wt), foram expostos a raios-X. Às dez semanas de recuperação após a radioterapia, o estado testicular e os parâmetros espermáticos foram avaliados. A expressão da RGN, bem como de vários reguladores do ciclo celular e da apoptose foi também avaliada. Para além disso, a actividade enzimática da caspase-3 foi determinada. Às dez semanas de recuperação após a radioterapia, tanto o estado testicular como os parâmetros espermáticos parecem ter sido menos afectados pelos raios-X nos Tg-RGN. Verificou-se ainda uma diminuição da expressão de p53 e de p21, o que pode indicar a reiniciação da espermatogénese. Para além disso, a reduzida actividade da caspase-3 detectada nos Tg-RGN está de acordo com os baixos níveis de caspase-8 e com o elevado rácio Bcl-2/Bax, sugerindo que os Tg-RGN são mais resistentes à apoptose testicular em resposta à radiação. A expressão de RGN aumentou significativamente nos ratos Wt, suportando o seu envolvimento na resposta anti-apoptótica. De forma geral, estes resultados indicam que a sobre-expressão da RGN desempenhou um papel protector relativamente ao dano testicular induzido pela radiação.
Μαρτίνου, Μαρία. "Μελέτη των ακτινοβιολογικών φαινομένων που παρατηρούνται μετά από έκθεση καρκινικών κυττάρων σε ιοντίζουσα ακτινοβολία χαμηλής δόσης. Η σημασία τους στη [sic] κλινική πράξη." Thesis, 2014. http://hdl.handle.net/10889/8532.
Full textThe effect of different doses of X(-)rays on apoptosis, proliferation, epidermal growth factor receptor (EGFR) and matrix metalloproteinase (MMP-2) expression was investigated in a human glioblastoma cell line. Materials and Methods: The cell line LN18 was irradiated at room temperature with doses ranging from 0.5 to 15 Gy using 6 MV X(-)rays. Apoptosis was assessed using the annexin V binding assay, proliferation by the methyl tetrazolium (MTT) assay and MMP-2 secretion with zymography. The levels of phosphorylated (pEGFR) were estimated using a commercially available ELISA kit. Results: Cell proliferation decreased in a dose-dependent manner, while apoptosis was increased after radiation. Doses below 2 Gy did not affect proliferation or apoptosis. MMP-2 levels were increased 48 h after radiation in a dose-dependent manner. In contrast, EGFR signaling was significantly activated 15 min after radiation in a dose-dependent manner. Conclusion: Ionizing radiation activates EGFR signalling and enhances MMP-2 secretion, suggesting that the molecular pathways involved may contribute to the invasiveness and malignant behaviour of glioma cells and help to explain the response of gliomas to ionizing radiation.
Yang, Pei-Yu, and 楊佩瑜. "Effect of Resistive Breathing Training on Radiation-Induced Diaphragm Contractile Dysfunction – Animal Study." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/51803517225513891078.
Full text國立臺灣大學
物理治療學研究所
102
Background: Radiotherapy (RT) had shown to induce acute diaphragm contractile dysfunction. Inspiratory muscle training (IMT) have proven to be effective in enhancing contractile function of the muscle; however, whether IMT prior to RT could ameliorate RT-related contractile dysfunction remains to be determined. Purposes: The purposes of this study were to investigate: 1) the effect of 1-week resistive breathing training on contractile function, antioxidant capacity and oxidative injury of the diaphragm; and 2) the effect of this training on RT-induced diaphragm contractile dysfunction and exploring the potential underlying mechanism in animal model. Methods: This study included two phases. In phase I, Sprague-Dawley (SD) rats were randomized into training (TG, n=7) or sham training (SG, n=6) group. TG received resistive breathing training using tracheal banding method for 1-week and SG received sham operation. Upon the completion of training, rats in both groups were sacrificed and the diaphragms were removed en bloc for contractile function assessment, antioxidant capacity and oxidative injury analysis. Antioxidant capacity analysis included total SOD activity, CuZnSOD and MnSOD mRNA expression. Oxidative injury was analyzed using protein carbonyl and 8-OHdG. In phase II, SD rats were randomized into training then RT (TR, n=6) or sham training then RT (SR, n=6) group. Training method was identical to that of phase I. After the completion of training, rats in both groups received one-shot 5 Gy RT to the diaphragm region. Twenty-four hours following RT, all rats were sacrificed and the diaphragms were removed for all the analyses as described in phase I. Generalized Estimated Equation and Generalized Linear Model were used to detect differences of variables between and within groups when suitable. Significant α level was set at 0.05. Results: Tracheal banding provided an average of 1.6 times increases in airway resistance. After 1-week of training, contractility (p<0.05), total SOD activity (p=0.004), and MnSOD mRNA expression (p=0.03) of the diaphragm were significantly higher in TG than those of SG. However, protein carbonyl level of the diaphragm were also increased after training (p<0.001). In phase II, contractility of the diaphragm were significantly higher (p<0.05), while fatigue index (p=0.002) and protein carbonyl level (p<0.001) were lower in TR than those of SR. Compared to SR, relative force-frequency curve showed significant downward shift between 30-50 Hz in TR. mRNA expression of CuZnSOD and MnSOD were significant higher in TR than those of SR (both p<0.05). Conclusions: This study showed that 1-week resistive breathing training could enhance diaphragm contractile function and thus reducing RT-induced its dysfunction through training related upregulation of antioxidant capacity of the diaphragm.
Li, Chen-yu, and 李晨宇. "Inhibitory effect of microwave radiation on LPS-induced NFκB cytokine expression in the THP-1 monocytes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/zaw97z.
Full text元培科技大學
醫學檢驗生物技術研究所
98
Microwave radiations, can be encountered regularly in daily lives. When World Health Organization (WHO) announced that microwave radiations as a kind of environmental energy which interferes with the physiological functions of human body, great concerns have been raised over the damage frequency can do to human physiology. The immunological performance and the activeness of cellular inflammatory factor NFκB have been closely related in monocyte. Due to the effect of phorbol 12-myristate 13-acetate (PMA) to THP-1 monocytes, THP-1 monocytes will divide into macrophages and will then react with lipopolysaccharides (LPS), and the amount of NFκB cytokine increases in THP-1 monocytes. Expression of cytokine will be affected when cells are exposed to frequency at 2450 MHz and are worked at 900W. Thus, from our experiments, an observation can be made when THP-1 monocytes are stimulated with PMA and LPS to differentiate into macrophage, the amount of NFκB cytokine in cells increases exponentially, and the level of expression is also restricted by the exposure of frequency. In conclusion, microwave radiations can inhibit the activity functions of THP-1 monocytes to be stimulated with PMA and LPS.
Martius, Gesa. "Effect of radiation on hepatic fat metabolism in rat and mouse: A role of radiation-induced TNF-α in the regulation of FAT/CD36." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-0022-607A-4.
Full textHubbard, Kenneth Roy. "Modelling induced fields in the human body exposed to electric fields from high voltage transmission lines designed to meet 10 kV/m at ground level." Thesis, 2017. http://hdl.handle.net/10539/23547.
Full textThere has been increasing public concern regarding adverse health effects due to power frequency electric and magnetic fields. Safety guidelines/standards for electric and magnetic field exposures have been established by different public organizations. However, the link between low frequency (power frequency) electric and magnetic field exposure and adverse health effects is not yet well established. Limits on human exposure to low frequency electric and magnetic fields are fundamentally specified for in-situ fields in tissues/organs. These dosimetric limits are referred to as Basic Restrictions for protection against potentially adverse effects from electro-stimulation. In addition, secondary limits, the exposure Reference Levels in environmental electric and magnetic fields are also given for practical compliance purposes. These are generally derived from the Basic Restrictions based on uniform-fields with a provision that the Basic Restrictions must be observed for non-uniform cases. In practice, any structure influences the electric fields in High Voltage systems, and thus creates electric field non-uniformity. The human exposure of the general public to electric fields from Eskom’s 765 kV transmission network operating at 50 Hz, is addressed through physical measurements, theoretical predictions and 3-D human model dosimetry, which is presented in this dissertation.
MT 2017
Ström, Petter. "Measurements of electric fields in a plasma by Stark mixing induced Lyman-α radiation." Thesis, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-206123.
Full textWang, Hung-Yi, and 王宏禕. "The study of Vit D photoprotection effect on radiation induced skin DNA damage in kerationcytes and malenocytes co-cultured system." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/01752797027344599752.
Full text國防醫學院
生物及解剖學研究所
101
Ultraviolet B (UVB) could directly damage DNA through producing thymine dimmer and lead to cell mutations. Skin cancer has highly relationship with these mutations. In skin cells, UVB in addition to damage the DNA, also stimulate vitamin D synthesis, promote DNA repair and production of melanin. However, until now there are still not any reports about photoprotection effect by Vit D on radiation induced skin DNA damage in kerationcytes and malenocytes co-cultured system. In this study we compared the differences of UVB induced damage among mono-culture of keratinocytes, melanocytes and co-culture of keratinocytes and melanocytes with different concentration of Vit D treatment. First, through MTT assay to analysis the cell survival rate of differences treatment, we found keratinocytes which have higher cell survival rate in 70nM Vit D. Malenocytes and co-culture system had no difference. And then we used the immunocytochemistry analysis to observe the variation of thymine dimer expressed in keratinocytes and melanocytes after UVB irradiation. Thymine dimmer would decrease along with the culture time increasing after irradiated by UVB, but not difference in different concentration of Vit D. Through flow cytometry analyses quantifying the fluorescence intensity of thymine dimmer showed keratinocytes didn’t reduce fluorescence intensity of thymine dimmer in different concentration of Vit D. We also found that co-culture of keratinocytes and melanocytes would decrease the expression of thymine dimer in Vit D treatment. Finally, we observed that co-cultured system with Vit D pre treatment really protect cell against UVB damage and it was obviously deceased the fluorescence intensity of thymine dimmer of cells. Since higher concertration Vit D could inhibit keratinocytes proliferate and promote terminal differention, so the protection effect is not significant in cell survival rate.
Enters, Dirk. "Aspect induced differences in vegetation and soil on north- and south-facing slopes in western Massachusetts /." 1999. https://scholarworks.umass.edu/theses/3476.
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