Biomolecular Action of Ionizing Radiation

Lehnert, Shirley

doi:10.1201/9781420011920

Cited by 110 publications

(143 citation statements)

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“…These interactions result in the immediate formation of hydroxyl radicals (OH • ) by the radiolysis of water and solvated electrons, both of which react with DNA. 11,12 In either the direct or indirect effect, ionizing radiation generates very large quantities of non-thermal secondary electrons (SEs) in cells (~ 4×10 4 by a 1 MeV particle) with a most probable energy lying below 10 eV. 13,14 Thus, in recent years much research interest has been focused on the fragmentation and modification of DNA by low energy electrons (LEEs).…”

Section: Introductionmentioning

confidence: 99%

“…1,12 Studies dealing with the influence of oxygen on radiation effects in living cells began as early as one hundred years ago and have continued extensively, as one of the most significant subjects in radiation science. 20,21 Quantitative studies of the relationship between oxygen concentration and radiation response has shown that exposure to high concentrations of oxygen causes greater damage in experimental animals and humans and that damage to DNA in malignant cells depends on the oxygenation of the tumor cells; e.g.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism is generally referred to as the oxygen fixation hypothesis (OFH), because it assumes that the addition of O 2 to the target radical fixes the damage so that it can not be repaired or restored. 12 In our laboratory, Cai et al 30 studied the damage to DNA in vacuum resulting from the emission of low energy secondary electrons from a metal surface exposed to soft X-rays. This method has recently been exploited by Brun et al 31 to investigate DNA damage under ambient atmospheric conditions.…”

Section: Introductionmentioning

confidence: 99%

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Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

et al. 2011

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DNA damage induced by low energy electrons (LEEs) and soft X-rays is measured under dry nitrogen and oxygen at atmospheric pressure and temperature. Five-monolayer plasmid DNA films deposited on tantalum and glass substrates are exposed to Al K α X-rays of 1.5 keV in the two different environments. From the damage yields for DNA, G-values are extracted for X-rays and LEEs. The G values for LEEs are 3.5 and 3.4 higher than those for X-ray photons under N 2 and O 2 atmospheres, respectively. Since most of the measured damage is in the form of single strand breaks (SSB), this result indicates a much higher effectiveness for LEEs relative to X-rays in causing SSB in both environments. The results indicate that the oxygen fixation mechanism, which is highly effective in increasing radiobiological effectiveness, under aerobic conditions, is operative on the type of damage created at the early stage of DNA radiolysis by LEEs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

et al. 2011

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“…The initial experiments on LEE-DNA were performed on DNA molecules under dry high vacuum conditions (Sanche, 2009;Boudaïffa et al, 2000;Cai et al, 2005). However, the damaging effects of LEEs on the DNA molecule are known to be dependent on its environment (Sanche, 2002;Lehnert, 2008;Ptasińska and Sanche, 2007;Barilla and Lokajíček, 2000). Thus, to better understand the damaging effects of LEE on DNA, attempts have been made to perform LEE-irradiation experiments under conditions more closely approximating those found in the cell.…”

Section: Introductionmentioning

confidence: 99%

Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

Alizadeh

Sanche

2012

Radiation Physics and Chemistry

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Five-monolayer (5ML) plasmid DNA films deposited on glass and tantalum substrates were exposed to Al K α X-rays of 1.5 keV under gaseous nitrous oxide (N 2 O) at atmospheric pressure and temperature. Whereas the damage yields for DNA deposited on glass are due to soft X-rays, those arising from DNA on tantalum are due to both the interaction of low energy photoelectrons from the metal and X-rays. Then, the differences in the yields of damage on glass and tantalum substrates, essentially arises from interaction of essentially low-energy electrons (LEEs) with DNA molecules and the surrounding atmosphere. The G-values (i.e., the number of moles of product per Joule of energy absorbed) for DNA strand breaks induced by LEEs (G LEE ) and the lower limit of G-values for soft X-ray photons (G XL ) were calculated and the results compared to those from previous studies under atmospheric conditions and other ambient gases, such as N 2 and O 2 . Under N 2 O, the G-values for loss of supercoiled DNA are 103±15 nmol/J for X-rays, and 737±110 nmol/J for LEEs. Compared to corresponding values in an O 2 atmosphere, the effectiveness of X-rays to damage DNA in N 2 O is less, but the G value for LEEs in N 2 O is more than twice the corresponding value for an oxygenated environment. This result indicates a higher effectiveness for LEEs relative to N 2 and O 2 environments in causing SSB and DSB in an N 2 O environment. Thus, the previously observed radiosensitization of cells by N 2 O may not be only due to OH • radicals but also to the reaction of LEE with N 2 O molecules near DNA. The previous experiments with N 2 and O 2 and the present one demonstrate the possibility to investigate damage induced by LEEs to biomolecules under various type of surrounding atmospheres.

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“…A relevant mathematical model should account for all variants of biological phenomena such as bystander effects (Prise et al 2003;Leonard 2008), adaptive responses (Feinendegen et al 2000), radiosensitivity, probability of natural death, cellular multiplication and mutation, and many others (ICRU 1983;Feinendegen and Pollycove 2001;Pollycove and Feinendegen 2003;Feinendegen and Neuman 2005;Lehnert 2007;Leonard 2008). This paper displays the results of simulations of possible The presented numerical loops contain the trees of probabilities, so purely mathematical values of these probabilities are intended to describe the biology of the cells (Lehnert 2007;ICRU 1983).…”

Section: Introductionmentioning

confidence: 99%

A Stochastic Markov Model of Cellular Response to Radiation

2011

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ᮀ A stochastic model based on the Markov Chain Monte Carlo process is used to describe responses to ionizing radiation in a group of cells. The results show that where multiple relationships linearly depending on the dose are introduced, the overall reaction shows a threshold, and, generally, a non-linear response. Such phenomena have been observed and reported in a number of papers. The present model permits the inclusion of adaptive responses and bystander effects that can lead to hormetic effects. In addition, the model allows for incorporating various time-dependent phenomena. Essentially, all known biological effects can be reproduced using the proposed model.

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Biomolecular Action of Ionizing Radiation

Cited by 110 publications

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Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

A Stochastic Markov Model of Cellular Response to Radiation

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Biomolecular Action of Ionizing Radiation

Cited by 110 publications

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Soft X-ray and Low Energy Electron-Induced Damage to DNA under N2 and O2 Atmospheres

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N2 and O2 Atmospheres

Induction of strand breaks in DNA films by low energy electrons and soft X-ray under nitrous oxide atmosphere

A Stochastic Markov Model of Cellular Response to Radiation

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Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres

Soft X-ray and Low Energy Electron-Induced Damage to DNA under N₂ and O₂ Atmospheres