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Laouameria AN, Hunyadi M, Csík A, Szűcs Z. Innovative Approach to Producing Palladium-103 for Auger-Emitting Radionuclide Therapy: A Proof-of-Concept Study. Pharmaceuticals (Basel) 2024; 17:253. [PMID: 38399468 PMCID: PMC10892908 DOI: 10.3390/ph17020253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Revised: 02/11/2024] [Accepted: 02/14/2024] [Indexed: 02/25/2024] Open
Abstract
Auger-emitting radionuclides, exemplified by Pd-103, exhibit considerable therapeutic potential in cancer treatment due to their high cytotoxicity and localized biological impact. Despite these advantages, the separation of such radionuclides presents a complicated challenge, requiring intricate and time-intensive "wet chemistry" methods attributed to the exceptional chemical inertness of the associated metals. This study proposes an innovative solution to this separation challenge through the design and implementation of a piece of radionuclide separation equipment (RSE). The equipment employs a dry distillation approach, capitalizing on differences in partial vapor pressures between irradiated and resulting radioactive metals, with a diffusion-driven extraction method applied to separate Pd-103 radionuclides generated via the proton irradiation of Rh-103 at cyclotron. Our optimization endeavors focused on determining the optimal temperature for effective metal separation and adjusting the diffusion, evaporation, and deposition rates, as well as addressing chemical impurities. The calculations indicate 17% ± 2% separation efficiency with our RSE. Approximately 77 ± 2% and 49 ± 2% of the deposited Pd-103 were isolated on substrates of Nb foil and ZnO-covered W disc, respectively. The proposed innovative dry distillation method that has been experimentally tested offers a promising alternative to conventional separation techniques, enabling enhanced purity and cost-efficient cancer treatment strategies.
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Affiliation(s)
- Aicha Nour Laouameria
- Doctoral School of Chemistry, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary
- HUN-REN Institute for Nuclear Research, Bem tér 18/c, 4026 Debrecen, Hungary; (M.H.); (A.C.); (Z.S.)
| | - Mátyás Hunyadi
- HUN-REN Institute for Nuclear Research, Bem tér 18/c, 4026 Debrecen, Hungary; (M.H.); (A.C.); (Z.S.)
| | - Attila Csík
- HUN-REN Institute for Nuclear Research, Bem tér 18/c, 4026 Debrecen, Hungary; (M.H.); (A.C.); (Z.S.)
| | - Zoltán Szűcs
- HUN-REN Institute for Nuclear Research, Bem tér 18/c, 4026 Debrecen, Hungary; (M.H.); (A.C.); (Z.S.)
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Hofmann W, Li WB, Friedland W, Miller BW, Madas B, Bardiès M, Balásházy I. Internal microdosimetry of alpha-emitting radionuclides. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2020; 59:29-62. [PMID: 31863162 PMCID: PMC7012986 DOI: 10.1007/s00411-019-00826-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 12/08/2019] [Indexed: 05/27/2023]
Abstract
At the tissue level, energy deposition in cells is determined by the microdistribution of alpha-emitting radionuclides in relation to sensitive target cells. Furthermore, the highly localized energy deposition of alpha particle tracks and the limited range of alpha particles in tissue produce a highly inhomogeneous energy deposition in traversed cell nuclei. Thus, energy deposition in cell nuclei in a given tissue is characterized by the probability of alpha particle hits and, in the case of a hit, by the energy deposited there. In classical microdosimetry, the randomness of energy deposition in cellular sites is described by a stochastic quantity, the specific energy, which approximates the macroscopic dose for a sufficiently large number of energy deposition events. Typical examples of the alpha-emitting radionuclides in internal microdosimetry are radon progeny and plutonium in the lungs, plutonium and americium in bones, and radium in targeted radionuclide therapy. Several microdosimetric approaches have been proposed to relate specific energy distributions to radiobiological effects, such as hit-related concepts, LET and track length-based models, effect-specific interpretations of specific energy distributions, such as the dual radiation action theory or the hit-size effectiveness function, and finally track structure models. Since microdosimetry characterizes only the initial step of energy deposition, microdosimetric concepts are most successful in exposure situations where biological effects are dominated by energy deposition, but not by subsequently operating biological mechanisms. Indeed, the simulation of the combined action of physical and biological factors may eventually require the application of track structure models at the nanometer scale.
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Affiliation(s)
- Werner Hofmann
- Biological Physics, Department of Chemistry and Physics of Materials, University of Salzburg, Hellbrunner Str. 34, 5020, Salzburg, Austria.
| | - Wei Bo Li
- Institute of Radiation Medicine, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany.
| | - Werner Friedland
- Institute of Radiation Medicine, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764, Neuherberg, Germany
| | - Brian W Miller
- Department of Radiation Oncology, School of Medicine, University of Colorado, Aurora, CO, 80045, USA
- College of Optical Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | - Balázs Madas
- Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
| | - Manuel Bardiès
- Centre de Recherches en Cancérologie de Toulouse, UMR 1037, INSERM Université Paul Sabatier, Toulouse, France
| | - Imre Balásházy
- Environmental Physics Department, MTA Centre for Energy Research, Budapest, Hungary
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Bayart E, Pouzoulet F, Calmels L, Dadoun J, Allot F, Plagnard J, Ravanat JL, Bridier A, Denozière M, Bourhis J, Deutsch E. Enhancement of IUdR Radiosensitization by Low-Energy Photons Results from Increased and Persistent DNA Damage. PLoS One 2017; 12:e0168395. [PMID: 28045991 PMCID: PMC5207426 DOI: 10.1371/journal.pone.0168395] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 11/29/2016] [Indexed: 01/10/2023] Open
Abstract
Low-energy X-rays induce Auger cascades by photoelectric absorption in iodine present in the DNA of cells labeled with 5-iodo-2’-deoxyuridine (IUdR). This photoactivation therapy results in enhanced cellular sensitivity to radiation which reaches its maximum with 50 keV photons. Synchrotron core facilities are the only way to generate such monochromatic beams. However, these structures are not adapted for the routine treatment of patients. In this study, we generated two beams emitting photon energy means of 42 and 50 keV respectively, from a conventional 225 kV X-ray source. Viability assays performed after pre-exposure to 10 μM of IUdR for 48h suggest that complex lethal damage is generated after low energy photons irradiation compared to 137Cs irradiation (662KeV). To further decipher the molecular mechanisms leading to IUdR-mediated radiosensitization, we analyzed the content of DNA damage-induced foci in two glioblastoma cell lines and showed that the decrease in survival under these conditions was correlated with an increase in the content of DNA damage-induced foci in cell lines. Moreover, the follow-up of repair kinetics of the induced double-strand breaks showed the maximum delay in cells labeled with IUdR and exposed to X-ray irradiation. Thus, there appears to be a direct relationship between the reduction of radiation survival parameters and the production of DNA damage with impaired repair of these breaks. These results further support the clinical potential use of a halogenated pyrimidine analog combined with low-energy X-ray therapy.
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Affiliation(s)
- Emilie Bayart
- INSERM U1030, Gustave Roussy, Université Paris-Saclay, Villejuif, France
- * E-mail:
| | - Frédéric Pouzoulet
- Plateforme de Radiothérapie Expérimentale, Département de Recherche Translationnelle, Institut Curie, Orsay, France
| | - Lucie Calmels
- Département de Radiothérapie, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Jonathan Dadoun
- Département de Radiothérapie, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Fabien Allot
- Département de Radiothérapie, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Johann Plagnard
- CEA, DRT/LIST, Laboratoire National Henri Becquerel, Gif-sur-Yvette cedex, France
| | - Jean-Luc Ravanat
- Laboratoire des Lésions des Acides Nucléiques, Univ. Grenoble Alpes, INAC-SCIB, Grenoble, France; CEA, INAC-SCIB, Grenoble, France
| | - André Bridier
- Département de Radiothérapie, Gustave Roussy, Université Paris-Saclay, Villejuif, France
| | - Marc Denozière
- CEA, DRT/LIST, Laboratoire National Henri Becquerel, Gif-sur-Yvette cedex, France
| | - Jean Bourhis
- Department of Oncology, Radiation Oncology Service, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Eric Deutsch
- INSERM U1030, Gustave Roussy, Université Paris-Saclay, Villejuif, France
- Faculté de médecine du Kremlin Bicêtre, Université Paris-Saclay, Kremlin Bicêtre, France
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Hsiao YY, Hung TH, Tu SJ, Tung CJ. Fast Monte Carlo simulation of DNA damage induction by Auger-electron emission. Int J Radiat Biol 2014; 90:392-400. [DOI: 10.3109/09553002.2014.892649] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Moskalev A, Plyusnina E, Shaposhnikov M, Shilova L, Kazachenok A, Zhavoronkov A. The role of D-GADD45 in oxidative, thermal and genotoxic stress resistance. Cell Cycle 2012; 11:4222-41. [PMID: 23095639 PMCID: PMC3524218 DOI: 10.4161/cc.22545] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
There is a relationship between various cellular stress factors and aging. In earlier studies, we demonstrated that overexpression of the D-GADD45 gene increases the life span of Drosophila melanogaster. In this study, we investigate the relationship between D-GADD45 activity and resistance to oxidative, genotoxic and thermal stresses as well as starvation. In most cases, flies with constitutive and conditional D-GADD45 overexpression in the nervous system were more stress-resistant than ones without overexpression. At the same time, most of the studied stress factors increased D-GADD45 expression in the wild-type strain. The lifespan-extending effect of D-GADD45 overexpression was also retained after exposure to chronic and acute gamma-irradiation, with doses of 40 сGy and 30 Gy, respectively. However, knocking out D-GADD45 resulted in a significant reduction in lifespan, lack of radiation hormesis and radioadaptive response. A dramatic decrease in the spontaneous level of D-GADD45 expression was observed in the nervous system as age progressed, which may be one of the causes of the age-related deterioration of organismal stress resistance. Thus, D-GADD45 expression is activated by most of the studied stress factors, and D-GADD45 overexpression resulted in an increase of stress resistance.
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Affiliation(s)
- Alexey Moskalev
- Laboratory of Molecular Radiobiology and Gerontology, Institute of Biology, Komi Science Center of Russian Academy of Sciences, Syktyvkar, Russia.
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Friedland W, Dingfelder M, Kundrát P, Jacob P. Track structures, DNA targets and radiation effects in the biophysical Monte Carlo simulation code PARTRAC. Mutat Res 2011; 711:28-40. [PMID: 21281649 DOI: 10.1016/j.mrfmmm.2011.01.003] [Citation(s) in RCA: 235] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Revised: 01/18/2011] [Accepted: 01/22/2011] [Indexed: 01/08/2023]
Abstract
This review describes the PARTRAC suite of comprehensive Monte Carlo simulation tools for calculations of track structures of a variety of ionizing radiation qualities and their biological effects. A multi-scale target model characterizes essential structures of the whole genomic DNA within human fibroblasts and lymphocytes in atomic resolution. Calculation methods and essential results are recapitulated regarding the physical, physico-chemical and chemical stage of track structure development of radiation damage induction. Recent model extension towards DNA repair processes extends the time dimension by about 12 orders of magnitude and paves the way for superior predictions of radiation risks.
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Affiliation(s)
- Werner Friedland
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
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Goorley T, Terrissol M, Nikjoo H. Calculated strand breaks from125I in coiled DNA. Int J Radiat Biol 2009; 84:1050-6. [DOI: 10.1080/09553000802478109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Pomplun E, Terrissol M, Kümmerle E. Estimation of a radiation weighting factor for 99mTc. RADIATION PROTECTION DOSIMETRY 2006; 122:80-1. [PMID: 17145726 DOI: 10.1093/rpd/ncl405] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Decaying (99m)Tc does not only emit a gamma ray (140.5 keV), but also low-energy Auger and conversion electrons. These electrons cause a serious problem in the determination of a radiation weighting factor for (99m)Tc due to their extremely short range in tissue. Therefore, for comparison ultrasoft X rays are used here, which deposit their energy mainly via the photoeffect thus also initiating low-energy photoelectrons. Monte Carlo computer codes provided electron emission spectra of (99m)Tc and subsequent track structure calculations simulated the induction of DNA damage of different degrees of complexity. For the modelling of ultrasoft X rays carbon K photons with an energy of 270 eV were selected, for which experimental results are available from the literature. On average, four electrons were found to be emitted per (99m)Tc decay. Simulation of DNA damage revealed a nearly identical spectrum of primary strand breaks for (99m)Tc and C-K radiation. On this basis, a total radiation weighting factor of 1.2 was evaluated for (99m)Tc.
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Affiliation(s)
- E Pomplun
- Geschäftsbereich Sicherheit und Strahlenschutz, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
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Corde S, Joubert A, Adam JF, Charvet AM, Le Bas JF, Estève F, Elleaume H, Balosso J. Synchrotron radiation-based experimental determination of the optimal energy for cell radiotoxicity enhancement following photoelectric effect on stable iodinated compounds. Br J Cancer 2004; 91:544-51. [PMID: 15266326 PMCID: PMC2409846 DOI: 10.1038/sj.bjc.6601951] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This study was designed to experimentally evaluate the optimal X-ray energy for increasing the radiation energy absorbed in tumours loaded with iodinated compounds, using the photoelectric effect. SQ20B human cells were irradiated with synchrotron monochromatic beam tuned at 32.8, 33.5, 50 and 70 keV. Two cell treatments were compared to the control: cells suspended in 10 mg ml−1 of iodine radiological contrast agent or cells pre-exposed with 10 μM of iodo-desoxyuridine (IUdR) for 48 h. Our radiobiological end point was clonogenic cell survival. Cells irradiated with both iodine compounds exhibited a radiation sensitisation enhancement. Moreover, it was energy dependent, with a maximum at 50 keV. At this energy, the sensitisation calculated at 10% survival was equal to 2.03 for cells suspended in iodinated contrast agent and 2.60 for IUdR. Cells pretreated with IUdR had higher sensitisation factors over the energy range than for those suspended in iodine contrast agent. Also, their survival curves presented no shoulder, suggesting complex lethal damages from Auger electrons. Our results confirm the existence of the 50 keV energy optimum for a binary therapeutic irradiation based on the presence of stable iodine in tumours and an external irradiation. Monochromatic synchrotron radiotherapy concept is hence proposed for increasing the differential effect between healthy and cancerous tissue irradiation.
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Affiliation(s)
- S Corde
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
| | - A Joubert
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
| | - J F Adam
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
| | - A M Charvet
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
| | - J F Le Bas
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
- Unité IRM, service de Neuroradiologie, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
| | - F Estève
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
- Unité IRM, service de Neuroradiologie, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
| | - H Elleaume
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
- IFR no. 1 ‘RMN biomédicale, de la cellule à l'homme’, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
| | - J Balosso
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
- Département de Cancérologie et d'Hématologie, Service de Radiothérapie, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France
- INSERM U647 ‘Rayonnement Synchrotron et Recherche Médicale’, Université Joseph Fourier & ID17 Biomedical Beamline of European Synchrotron Radiation Facility, CHU A Michallon, BP 217, 38043 Grenoble Cedex 09, France. E-mail:
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Kümmerle EA, Pomplun E. A computer-generated supercoiled model of the pUC19 plasmid. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2004; 34:13-8. [PMID: 15300338 DOI: 10.1007/s00249-004-0431-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Revised: 06/18/2004] [Accepted: 06/22/2004] [Indexed: 10/26/2022]
Abstract
DNA models have become a powerful tool in the simulation of radiation-induced molecular damage. Here, a computer code was developed which calculates the coordinates of individual atoms in supercoiled plasmid DNA. In this prototype study, the known base-pair sequence of the pUC19 plasmid has been utilized. The model was built in a three-step process. Firstly, a Monte Carlo simulation was performed to shape a segment chain skeleton. Checks on elastic energy, distance and unknotting were applied. The temperature was considered in two different ways: (1) it was kept constant at 293 K and (2) it was gradually reduced from 350 K to less than 10 K. Secondly, a special smoothing procedure was introduced here to remove the edges from the segment chain without changing the total curve length while avoiding the production of overshooting arcs. Finally, the base pair sequence was placed along the smoothed segment chain and the positions of all the atoms were calculated. As a first result, a few examples of the supercoiled plasmid models will be presented, demonstrating the strong influence of appropriate control of the system temperature.
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Affiliation(s)
- E A Kümmerle
- Geschäftsbereich Sicherheit und Strahlenschutz, Forschungszentrum Jülich, 52425 Jülich, Germany.
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11
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Abstract
The ability of low-energy electrons to induce single- and double-strand breaks in DNA has recently been demonstrated. Here we show the propensity of 3-30 eV electrons to initiate base sequence-dependent damage to a short single DNA strand. Solid monolayer films of homogeneous thymidine (T(9)) and deoxycytidine (dCy(9)) and heterogeneous oligomers (T(6)dCy(3)) are bombarded with 1-30 eV electrons in an ultrahigh-vacuum system. CN, OCN and/or H(2)NCN are detected by a mass spectrometer as the most intense neutral fragments desorbing in vacuum. A weaker signal of CH(3)CCO is also detected, but only from oligonucleotides containing thymine. Below 17 eV, the energy dependence of the yields of CN, OCN and CH(3)CCO exhibits resonance-like structures, attributed to dissociative electron attachment (DEA). Above 17 eV, the monotonic increase in the fragment yields indicates that nonresonant processes (i.e. dipolar dissociation) control the fragmentation of these molecules. Within the energy range investigated, comparison of the magnitude of the total fragment yields produced by electron attack on dCy(9), T(6)-dCy(3) and T(9) suggests the following order in the sensitivity of single-strand DNA: dCy(9) > T(6)-dCy(3) > T(9). At 12 eV, the total fragment yields are found to be 5.8, 5.0 and 3.9 x 10(-3) fragment/electron, respectively. From the yields obtained with the two homo-oligonucleotides, we differentiate between contributions arising from the chemical nature of the base and the effect of environment (i.e. the sequence) when a thymidine unit in T(9) is replaced by dCy. The base sequence-dependent damage is found to vary with incident electron energy. These results reinforce the idea that genomic sensitivity to ionizing radiation depends on local genetic information. Furthermore, they underscore the possible role of low-energy electrons in the pathways responsible for the induction of specific genomic lesions.
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Affiliation(s)
- H Abdoul-Carime
- Groupe des Institutes Canadiens de Recherches en Santé en Sciences des Radiations, Département de Médecine Nucléaire et de Radiobiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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12
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Nikjoo H, Panyutin IG, Terrissol M, Vrigneaud JM, Laughton CA. Distribution of strand breaks produced by Auger electrons in decay of 125I in triplex DNA. Acta Oncol 2001; 39:707-12. [PMID: 11130008 DOI: 10.1080/028418600750063767] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In this study we investigate the possibility of using Auger electrons as a probing agent for the study of structures of nucleic acids. To this end, we present the distribution of breaks produced in strands of a DNA duplex and a triplex-forming oligonucleotide (TFO) carrying Auger emitting radionuclide 125I. The method of calculation includes use of a molecular model of plasmid DNA duplex with bound TFO carrying a labelled 125I at position C5 of a single deoxycytosine residue, a source of Auger spectra, Monte Carlo electron track structure and the ensuing chemistry codes, to simulate the distribution of breaks produced in both strands of a plasmid DNA. Frequencies of fragment length distributions were obtained for the TFO, the purine and the pyrimidine strands. The frequency of breaks in the purine strand showed good correlation with the published experimental results, while that for the pyrimidine strand is lower by a factor of 3. It is concluded that the true structure of triplex DNA may not be purely of B-form.
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Affiliation(s)
- H Nikjoo
- MRC Radiation and Genome Stability Unit, Harwell, Oxfordshire, UK.
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Abstract
Radionuclide decay by electron capture and/or internal conversion is accompanied by complex atomic vacancy cascades and emission of low-energy electrons, resulting in a highly charged daughter atom and a high density of electron irradiation in the immediate vicinity of the decay site. The molecular and cellular consequences of such decay events include DNA strand breaks, mutations, chromosome aberrations, malignant transformation, division delay, and cell death. Damage to cells depends largely on the intracellular location of the radionuclide. Decays outside the cell nucleus produce low-LET-type radiation effects (RBE approximately 1). In contrast, decays in DNA cause pronounced high-LET-type effects (RBE approximately 7-9). However, recent studies suggest that even for DNA-associated Auger emitters cell damage can be modified to resemble the pattern observed with low-LET radiations. These findings indicate that the molecular and cellular mechanism(s) responsible for the cytotoxic effects of Auger emitters remain obscure.
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Affiliation(s)
- K G Hofer
- Institute of Molecular Biophysics, Florida State University, Tallahassee 32306, USA
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14
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Pomplun E, Terrissol M, Demonchy M. Modelling of initial events and chemical behaviour of species induced in DNA units by Auger electrons from 125I, 123I and carbon. Acta Oncol 1996; 35:857-62. [PMID: 9004763 DOI: 10.3109/02841869609104037] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Auger electron spectra for 123I and 125I generated by Monte Carlo calculation and Auger electrons emitted from carbon after photoelectric effect on its K-shell as well as two DNA models (linear plasmid and nucleosome model) based on x-ray diffraction experiments have been used to simulate the behaviour of all species and radicals created during the physical and the chemical phase of the Auger's transport. By introducing appropriate assumptions for the induction of strand breaks the number of these breaks can also be determined and correlated to experimentally found numbers of lethal events. Efficiency differences between the iodine nuclides themselves and in comparison with the rather monoenergetic Auger electrons from carbon are shown with regard to the direct and indirect effects on the two DNA models. The characteristic products in the physical, chemical and biochemical phase are compared with corresponding results from the literature for low-LET radiation.
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Affiliation(s)
- E Pomplun
- Abteilung Sicherheit und Strahlenschutz, Forschungszentrum Jülich GmbH, Jülich, Germany
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