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Singleton EV, Gates CJ, David SC, Hirst TR, Davies JB, Alsharifi M. Enhanced Immunogenicity of a Whole-Inactivated Influenza A Virus Vaccine Using Optimised Irradiation Conditions. Front Immunol 2021; 12:761632. [PMID: 34899711 PMCID: PMC8652198 DOI: 10.3389/fimmu.2021.761632] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Influenza A virus presents a constant pandemic threat due to the mutagenic nature of the virus and the inadequacy of current vaccines to protect against emerging strains. We have developed a whole-inactivated influenza vaccine using γ-irradiation (γ-Flu) that can protect against both vaccine-included strains as well as emerging pandemic strains. γ-irradiation is a widely used inactivation method and several γ-irradiated vaccines are currently in clinical or pre-clinical testing. To enhance vaccine efficacy, irradiation conditions should be carefully considered, particularly irradiation temperature. Specifically, while more damage to virus structure is expected when using higher irradiation temperatures, reduced radiation doses will be required to achieve sterility. In this study, we compared immunogenicity of γ-Flu irradiated at room temperature, chilled on ice or frozen on dry ice using different doses of γ-irradiation to meet internationally accepted sterility assurance levels. We found that, when irradiating at sterilising doses, the structural integrity and vaccine efficacy were well maintained in all preparations regardless of irradiation temperature. In fact, using a higher temperature and lower radiation dose appeared to induce higher neutralising antibody responses and more effective cytotoxic T cell responses. This outcome is expected to simplify irradiation protocols for manufacturing of highly effective irradiated vaccines.
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Affiliation(s)
- Eve Victoria Singleton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Chloe Jayne Gates
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Shannon Christa David
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Timothy Raymond Hirst
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, Australia
- Gamma Vaccines Pty Ltd, Yarralumla, ACT, Australia
| | - Justin Bryan Davies
- Irradiations Group, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, Australia
| | - Mohammed Alsharifi
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, Australia
- Gamma Vaccines Pty Ltd, Yarralumla, ACT, Australia
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Singleton EV, David SC, Davies JB, Hirst TR, Paton JC, Beard MR, Hemmatzadeh F, Alsharifi M. Sterility of gamma-irradiated pathogens: a new mathematical formula to calculate sterilizing doses. JOURNAL OF RADIATION RESEARCH 2020; 61:886-894. [PMID: 32930781 PMCID: PMC7674690 DOI: 10.1093/jrr/rraa076] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 06/19/2020] [Indexed: 06/11/2023]
Abstract
In recent years there has been increasing advocacy for highly immunogenic gamma-irradiated vaccines, several of which are currently in clinical or pre-clinical trials. Importantly, various methods of mathematical modelling and sterility testing are employed to ensure sterility. However, these methods are designed for materials with a low bioburden, such as food and pharmaceuticals. Consequently, current methods may not be reliable or applicable to estimate the irradiation dose required to sterilize microbiological preparations for vaccine purposes, where bioburden is deliberately high. In this study we investigated the applicability of current methods to calculate the sterilizing doses for different microbes. We generated inactivation curves that demonstrate single-hit and multiple-hit kinetics under different irradiation temperatures for high-titre preparations of pathogens with different genomic structures. Our data demonstrate that inactivation of viruses such as Influenza A virus, Zika virus, Semliki Forest virus and Newcastle Disease virus show single-hit kinetics following exposure to gamma-irradiation. In contrast, rotavirus inactivation shows multiple-hit kinetics and the sterilizing dose could not be calculated using current mathematical methods. Similarly, Streptococcus pneumoniae demonstrates multiple-hit kinetics. These variations in killing curves reveal an important gap in current mathematical formulae to determine sterility assurance levels. Here we propose a simple method to calculate the irradiation dose required for a single log10 reduction in bioburden (D10) value and sterilizing doses, incorporating both single- and multiple-hit kinetics, and taking into account the possible existence of a resistance shoulder for some pathogens following exposure to gamma-irradiation.
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Affiliation(s)
- Eve V Singleton
- Research Centre for Infectious Diseases, and Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Shannon C David
- Research Centre for Infectious Diseases, and Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Justin B Davies
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - Timothy R Hirst
- Research Centre for Infectious Diseases, and Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
- Gamma Vaccines Pty Ltd, Mountbatten Park, Yarralumla, ACT, 2600, Australia
- GPN Vaccines Pty Ltd, Mountbatten Park, Yarralumla, ACT, 2600, Australia
| | - James C Paton
- Research Centre for Infectious Diseases, and Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
- GPN Vaccines Pty Ltd, Mountbatten Park, Yarralumla, ACT, 2600, Australia
| | - Michael R Beard
- Research Centre for Infectious Diseases, and Department of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Farhid Hemmatzadeh
- School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, SA, 5371, Australia
| | - Mohammed Alsharifi
- Corresponding author. Research Centre for Infectious Diseases, University of Adelaide, Adelaide, SA, 5005, Australia.
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David SC, Lau J, Singleton EV, Babb R, Davies J, Hirst TR, McColl SR, Paton JC, Alsharifi M. The effect of gamma-irradiation conditions on the immunogenicity of whole-inactivated Influenza A virus vaccine. Vaccine 2017; 35:1071-1079. [PMID: 28109709 DOI: 10.1016/j.vaccine.2016.12.044] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/25/2016] [Accepted: 12/16/2016] [Indexed: 11/27/2022]
Abstract
Gamma-irradiation, particularly an irradiation dose of 50kGy, has been utilised widely to sterilise highly pathogenic agents such as Ebola, Marburg Virus, and Avian Influenza H5N1. We have reported previously that intranasal vaccination with a gamma-irradiated Influenza A virus vaccine (γ-Flu) results in cross-protective immunity. Considering the possible inclusion of highly pathogenic Influenza strains in future clinical development of γ-Flu, an irradiation dose of 50kGy may be used to enhance vaccine safety beyond the internationally accepted Sterility Assurance Level (SAL). Thus, we investigated the effect of irradiation conditions, including high irradiation doses, on the immunogenicity of γ-Flu. Our data confirm that irradiation at low temperatures (using dry-ice) is associated with reduced damage to viral structure compared with irradiation at room temperature. In addition, a single intranasal vaccination with γ-Flu irradiated on dry-ice with either 25 or 50kGy induced seroconversion and provided complete protection against lethal Influenza A challenge. Considering that low temperature is expected to reduce the protein damage associated with exposure to high irradiation doses, we titrated the vaccine dose to verify the efficacy of 50kGy γ-Flu. Our data demonstrate that exposure to 50kGy on dry-ice is associated with limited effect on vaccine immunogenicity, apparent only when using very low vaccine doses. Overall, our data highlight the immunogenicity of influenza virus irradiated at 50kGy for induction of high titre antibody and cytotoxic T-cell responses. This suggests these conditions are suitable for development of γ-Flu vaccines based on highly pathogenic Influenza A viruses.
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Affiliation(s)
- Shannon C David
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Josyane Lau
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Eve V Singleton
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Rachelle Babb
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Justin Davies
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Timothy R Hirst
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia; Gamma Vaccines Pty Ltd, Mountbatten Park, Yarralumla, ACT 2600, Australia
| | - Shaun R McColl
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - James C Paton
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Mohammed Alsharifi
- Research Centre for Infectious Diseases, and Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia; Gamma Vaccines Pty Ltd, Mountbatten Park, Yarralumla, ACT 2600, Australia.
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Riesz P, Smitherman TC. Radiation-Induced Hydrogen Transfer in Nucleic Acids and Proteins in the Solid State. Isr J Chem 2013. [DOI: 10.1002/ijch.197200122] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Lemay R, Tremblay-Morin JP, Ali H, Hunting D, van Lier JE, Paquette B. Synthesis and radiosensitizing properties of brominated tetrapyridine porphyrins. J PORPHYR PHTHALOCYA 2012. [DOI: 10.1142/s1088424607000643] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Brominated derivatives of tetrapyridinium copper porphyrin were prepared via bromination of the β-positions (pyrrole rings) and/or the peripheral alkyl side-chains attached to the pyridine moieties. The radiosensitizing properties of these new cationic, brominated porphyrins were tested on MDA-MB-231 breast cancer cells in vitro using a 60 Co source or an X-ray irradiator. The non-brominated porphyrin and the porphyrin containing bromines at β-positions only were devoid of any radiosensitizing activity. However, a pronounced radiosensitizing effect was observed with the porphyrin containing bromo atoms at both β-positions and the peripheral side-chains. A similar radiosensitizing effect was detected for different radiation energies, suggesting that high energy photons could be used to treat tumors in conjunction with this novel brominated, porphyrin-based radiosensitizer.
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Affiliation(s)
- Rosalie Lemay
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec J1H 5N4, Canada
| | - Jean-Philippe Tremblay-Morin
- Department of Chemistry, Faculty of Sciences, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec J1K 2R1, Canada
| | - Hasrat Ali
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec J1H 5N4, Canada
| | - Darel Hunting
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec J1H 5N4, Canada
| | - Johan E. van Lier
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec J1H 5N4, Canada
| | - Benoit Paquette
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th Avenue North, Sherbrooke, Québec J1H 5N4, Canada
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Sharma KKK, Swarts SG, Bernhard WA. Mechanisms of direct radiation damage to DNA: the effect of base sequence on base end products. J Phys Chem B 2011; 115:4843-55. [PMID: 21473599 DOI: 10.1021/jp200902h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
It has been generally assumed that product formation in DNA damaged by ionizing radiation is relatively independent of base sequence, i.e., that the yield of a given product depends primarily on the chemical properties of each DNA constituent and not on its base sequence context. We examined this assumption by comparing direct-type end products produced in films of d(CTCTCGAGAG)(2) with those produced in films of d(GCACGCGTGC)(2). Here we report the product yields in d(CTCTCGAGAG)(2) hydrated to Γ = 2.5 and 15, where Γ is the hydration level given in moles of H(2)O/mole of nucleotide. Of the 17 products monitored by GC/MS, seven exhibited statistically significant yields: 8-oxoGua, 8-oxoAde, 5-OHMeUra, 5,6-diHUra, 5,6-diHThy, 5-OHCyt, and 5-OHUra. These yields at Γ = 2.5 are compared with the yields from our previously reported study of d(GCACGCGTGC)(2) (after projecting the yields to a CG/AT ratio of 1). The ratio of projected yields, d(CTCTCGAGAG)(2) divided by d(GCACGCGTGC)(2), are 1.3 ± 0.9, 1.8 ± 0.3, 1.6 ± 0.6, 11.4 ± 4.7, 0.2 ± 0.1, >28, and 0.8 ± 1.1, respectively. Considering just d(CTCTCGAGAG)(2), the ratios of yields at Γ = 2.5 divided by yields at Γ = 15 are 0.7 ± 0.2, 0.5 ± 0.1, 2.3 ± 4.0, 3.4 ± 1.2, 3.5 ± 3.3, 1.2 ± 0.2, and 0.4 ± 0.2, respectively. The effects of sequence and hydration on base product yields are explained by a working model emphasizing the difference between two distinctly different types of reaction: (i) radical reactions that progress to nonradical intermediates and product prior to dissolution and (ii) reactions that stem from radicals trapped in the solid state at room temperature that go on to yield nonradical product after sample dissolution. Based on these findings, insights into rates of hole and excess electron-transfer relative to rates of proton transfer are discussed.
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Affiliation(s)
- Kiran K K Sharma
- School of Chemical Sciences, North Maharashtra University, Jalgaon, Maharashtra, India
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Adamo C, Cossi M, Rega N, Barone V. New computational strategies for the quantum mechanical study of biological systems in condensed phases. THEORETICAL AND COMPUTATIONAL CHEMISTRY 2001. [DOI: 10.1016/s1380-7323(01)80013-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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A multi-component model for radiation damage to DNA from its constituents. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1380-7323(01)80012-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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9
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McGinn CJ, Kinsella TJ. The clinical rationale for S-phase radiosensitization in human tumors. Curr Probl Cancer 1993; 17:273-321. [PMID: 8281809 DOI: 10.1016/0147-0272(93)90012-q] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Nonhypoxic cell radiosensitizers, principally the halogenated pyrimidines and hydroxyurea, have been studied in the laboratory and clinical setting for more than 30 years. Early clinical experience in the 1960s and 1970s with the thymidine analogs 5-bromodeoxyuridine (BUdR) and 5-iododeoxyuridine (IUdR) was disappointing because normal tissue toxicity eliminated any potential for therapeutic gain. Inadequate delivery systems for intravenous and intraarterial infusions also contributed to the decline of this strategy. More recently, laboratory investigations have revealed further information regarding the mechanism of IUdR/BUdR radiosensitization. This knowledge provided a rationale for the sequence and timing of drug and radiation exposure, which could be both effective and tolerable. Advancing technology also provided safer infusion devices, and a resurgence in clinical trials combining IUdR or BUdR and radiation resulted. Current laboratory studies are now providing data on tumor cell kinetics, which is being applied to ongoing clinical trials. Fluoropyrimidines, principally 5-fluorouracil (5-FU), were also used in early clinical trials and unlike IUdR/BUdR were found to have significant activity as single agents against a variety of tumor types. The clinical integration of 5-FU and radiation occurred more slowly, but recent trials have demonstrated a therapeutic gain. Improved rates of local control and survival with combined 5-FU and radiation versus radiation alone have now been demonstrated in patients with rectal, esophageal, and anal carcinomas. However, the mechanism of interaction between the fluoropyrimidines and radiation remains uncertain and continues to be investigated with the hope of improved clinical outcome. As the cellular pathways influenced by the halogenated pyrimidines have been defined, the potential for biochemical modulation of these agents has been recognized. Leucovorin, the most commonly applied modulator, has been shown to enhance the activity of 5-FU in patients with metastatic colorectal carcinoma. These studies serve as an example for current trials that use biochemical modulators of IUdR, BUdR, and 5-FU as radiosensitizers. Hydroxyurea, currently used in the treatment of chronic leukemia, has also been considered a radiosensitizer. As with IUdR/BUdR, the clinical trials have often been inconclusive and interest in this radiosensitizer has waned. A poor understanding of the mechanism of action and tumor cell/normal tissue kinetics may be responsible for the lack of overall success with this strategy. Current investigations of cell kinetics in humans and potential mechanisms of hydroxyurea action could provide information critical to future trials of hydroxyurea radiosensitization.
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Affiliation(s)
- C J McGinn
- Department of Human Oncology, University of Wisconsin Medical School, Madison
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Poot M, Schuster A, Hoehn H. Cytostatic synergism between bromodeoxyuridine, bleomycin, cisplatin and chlorambucil demonstrated by a sensitive cell kinetic assay. Biochem Pharmacol 1991; 41:1903-9. [PMID: 1710121 DOI: 10.1016/0006-2952(91)90130-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Bromodeoxyuridine/Hoechst flow cytometry was used to analyse the interference of common cytostatic agents with cell activation and cell cycle progression of human B-cell lines. Bleomycin impaired both cell activation and G2 transit, the latter effect being oxygen dependent. The DNA alkylating agents cyclophosphamide, chlorambucil and mitomycin C caused G2 arrest, whereas cisplatin arrested cells in both the S and G2 phase of the cell cycle. Vinblastin interfered with mitosis, but in addition arrested cells in all phases of the cell cycle. The growth inhibitory action of bleomycin, cisplatin and chlorambucil was dependent upon the bromodeoxyuridine (BrdU) concentration in the culture medium. No interaction was found between BrdU and cyclophosphamide, mitomycin C and vinblastin. The cell cycle kinetic mechanism of the interaction between BrdU and bleomycin, cisplatin and chlorambucil was a potentiation of the G2 arrest. In conclusion, BrdU may be useful in clinical chemotherapy as a chemosensitizer for selected cytostatic agents.
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Affiliation(s)
- M Poot
- Department of Human Genetics, University of Würzburg, Federal Republic of Germany
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Abstract
The molecular structure as well as the mechanisms of formation and decay of free radicals produced in DNA and its constituents by ionizing radiation is reviewed. Starting with the description of the spectral parameters for cations and anions in natural nucleic acid bases, emphasis is given to the comparable species formed in the group of the 5-halogen substituted uracil derivatives. The consequences of the attachment of a ribose or ribosephosphate group to the bases is discussed in terms of the distribution of primary radicals which, again, is shown to be different from those of the subunits in DNA itself. The quantitative aspects of radical formation are discussed in terms of G values and their dependence on the temperature of irradiation. Finally, a schematic presentation of the major modes of radical reactions is given occurring upon warming of the primary species in the DNA subunits and in DNA itself.
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Kuwabara M, Yoshii G. Electron transfer between protein and DNA in gamma-irradiated deoxyribonucleoprotein. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 432:292-9. [PMID: 178378 DOI: 10.1016/0005-2787(76)90138-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
When deoxyribonucleoprotein-proflavine complexes were studied by electron spin-resonance spectroscopy following gamma-irradiation, it was found that stable free radicals were not formed at random on the complex but were preferentially located on proflavine. Since proflavine intercalalated to DNA bases serves as a final acceptor of electrons liberated by ionization, the result of our experiment was regarded as suggesting that the electron transfer from the protein moiety to the DNA moiety occurred in the irradiated deoxyribonucleoprotein.
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Van de Vorst A. Effets indirects dans les solutions aqueuses de thymidine-5′-monophosphate irradiees par rayons X a 77 K. ACTA ACUST UNITED AC 1974. [DOI: 10.1016/0020-7055(74)90021-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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17
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Gräslund A, Ehrenberg A, Rupprecht A, Ström G. Ionic base radicals in -irradiated DNA. BIOCHIMICA ET BIOPHYSICA ACTA 1971; 254:172-86. [PMID: 4332768 DOI: 10.1016/0005-2787(71)90826-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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18
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On the mechanism of formation of free radicals induced in nucleic acid bases by ionizing radiation. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/0020-7055(71)90015-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Lion Y, van de Vorst A. Formation de radicaux anioniques par irradiation X de bases puriques dans des verres alcalins. ACTA ACUST UNITED AC 1971. [DOI: 10.1016/0020-7055(71)90016-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lenherr AD, Ormerod MG. Formation of the thymine radical in irradiated DNA. BIOCHIMICA ET BIOPHYSICA ACTA 1968; 166:298-310. [PMID: 4300633 DOI: 10.1016/0005-2787(68)90220-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Lacroix M, Van de Vorst A. [Free radicals induced by the action of ultraviolet radiation on certain constituants of deoxyribonucleic acid]. Photochem Photobiol 1968; 7:477-83. [PMID: 4305318 DOI: 10.1111/j.1751-1097.1968.tb07408.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Ehrenberg A, Rupprecht A, Ström G. Electron spin resosnance of gamma-irradiated oriented DNA prepared by wet spinning. Science 1967; 157:1317-9. [PMID: 4292254 DOI: 10.1126/science.157.3794.1317] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
When moist, oriented DNA is gamma-irradiated and its electron spin resonance spectrum is recorded at 77 degrees K, an unresolved spectrum is obtained, the amplitude of which is strongly dependent on the angle between the direction of the DNA helices and the field. Annealing at 199 degrees K gives an eight-line thymine-like spectrum which also has a marked angular dependence. For dry, oriented DNA, the unresolved spectrum dominates even at room temperature, and the spectra exhibit lower degrees of anisotropy.
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Effects of Ionizing Radiations on Biological Macromolecules. ACTA ACUST UNITED AC 1967. [DOI: 10.1016/b978-1-4831-9716-6.50016-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
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