Yield of Strand Breaks as a Function of Scavenger Concentration and LET for SV40 Irradiated with 4 He Ions

Jones, George D.D.; Milligan, Jamie R.; Ward, John F.; Calabro-Jones, Paula M.; Aguilera, Joseph

doi:10.2307/3578610

Cited by 60 publications

(28 citation statements)

References 24 publications

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“…The original level of SSBs at zero dosage is negligible, therefore, this straight line can be well fitted by SSB=kD with D representing the radiation dose. The above result supports the assumption of SSB induction being due to the one-hit event of • OH radicals [17,18]. Figure 1 also shows that the induction of DSBs is a linear-quadratic function of radiation dose and can be well fitted by DSB=αD+βD 2 , where α is the number of DSBs per unit dose induced in one irradiation event and β the number of DSB per unit squared dose induced by the combination of two independent SSB.…”

Section: Resultssupporting

confidence: 78%

“…If at a very high σ value such as 10 10 s -1 , αDSB is induced only by the direct effect of irradiation energy deposition [2,17], then G dir (αDSB), the yield of αDSBs induced by the direct effect, equals about 3.4×10 8 µmol J -1 obtained earlier in a 37.5 µg ml -1 pBR322 solution [8]. Figure 3 shows that at this DNA concentration, G(αDSB) equals 2.6×10 -6 µmol J -1 , thus G dir (αDSB) occupies only a very small part of G(αDSB) so that it can be neglected.…”

Section: Estimate Of Rate Constant For αDsb Inductionmentioning

confidence: 99%

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Reaction rate coefficients of hydroxyl radical-induced DNA single- and α-type double-strand breaks

Shao¹,

Zhang²,

Saito

2000

Radiation and Environmental Biophysics

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With a model system of pBR322 plasmid DNA solution in vitro, the dose effects of radiation-induced single- and double-strand breaks (SSB and DSB) were measured and DSB was distinguished into alpha- and beta-types. Under the condition of low scavenging capacity existing in the irradiated DNA solution, SSB and alpha DSB were mainly induced by hydroxyl radicals (.OH). Moreover, a certain relationship was obtained between the SSB and alpha DSB yields and the DNA concentration. It was found that when the DNA solution was irradiated in the presence of 2.5 mmol dm-3 mannitol, the reciprocals of G(SSB) and G(alpha DSB), respectively, were linearly related to the reciprocal of the DNA concentration, i.e. the competition reactions of DNA and mannitol for .OH radicals can be described by second-order kinetics. The rate coefficients and the efficiencies of the .OH radical inducing SSB were deduced. Also, the reaction rate coefficients and the efficiencies for the induction of alpha DSB from SSB by the .OH radical transfer mechanism, were first derived from the competition kinetics.

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Section: Resultssupporting

confidence: 78%

Section: Estimate Of Rate Constant For αDsb Inductionmentioning

confidence: 99%

Reaction rate coefficients of hydroxyl radical-induced DNA single- and α-type double-strand breaks

Shao¹,

Zhang²,

Saito

2000

Radiation and Environmental Biophysics

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“…6a, we get an average number of Â = (0.054 ± 0.012) DSBs/(MbpGy). This result is in the expected range and consistent with the findings of Jones et al [36]. They found a value of Â = 0.052 DSBs/(MbpGy).…”

Section: Experimental Data and Discussionsupporting

confidence: 93%

Scanning force microscopy studies of X-ray-induced double-strand breaks in plasmid DNA

2009

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We present an analysis of X-ray-induced damage in X174 plasmid DNA, applying doses between D = 250 and 1,500 Gy. To analyse this damage in detail, the distribution of plasmid fragments after irradiation have been determined by scanning force microscopy. The results show that even for the lowest dose of D = 250 Gy, a significant amount of double-strand breaks are observed. For increasing dose, the percentage of small fragments increases and is accompanied by a shortening of the average fragment length from < L >= 1,400 nm for a dose of D = 250 Gy to < L >= 1,080 nm after irradiation with D = 1,500 Gy. The most crucial parameter, the average number of double-strand breaks per broken plasmid () has been determined for the first time for the applied doses. The results show that the average number of DSBs per broken plasmid increases almost linearly from a value of = 1.3 after irradiation with D = 250 Gy to = 1.7 after exposure to D = 1,500 Gy. The presented results show that the amount of DSBs induced by X-ray radiation in plasmid DNA can be calculated with high accuracy by means of scanning force microscopy, providing relevant information regarding the interaction of X-rays with DNA molecules.

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“…The yield of multiple MN exceeds what is expected if the observed MN at each dose level follows a Poisson distribution (Table 1). It is tempting to relate the production of multiple MN to the expression of locally multiple damage sites (Ward 1981;Jones et al 1993). Alternatively, this finding may be the simple expression of severe chromosomal damage sustained by a fraction of the cell population, even at low doses, whereas other ceils may not be damaged at all.…”

Section: Discussionmentioning

confidence: 99%

Micronucleus induction and reproductive death in a human cell line exposed to low-energy argon beam

Courdi

Mari

Hérault

et al. 1995

Radiat Environ Biophys

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Little is known about the action of charged particles of very high linear energy transfer (LET) on human cells and, in particular, the relationship between DNA damage and reproductive death. The aim of this study was to measure the biological efficiency of a low-energy argon beam (E = 7.1 MeV/nucleon, LET = 1590 keV/micron) produced at GSI, Darmstadt, on a human melanoma cell line (CAL4) established in our Institute. Two different methods were used: the micronucleus (MN) test and the colony-forming assay. The MN test, using the cytochalasin-block method, is a measure of genotoxic damage. MN are scored in binucleate cells (BNC) and are formed from acentric fragments or whole chromosomes that have not been incorporated into daughter nuclei at mitosis. The colony-forming assay quantifies reproductive death. Parallel experiments were run with cobalt gamma-rays for comparison. After Co irradiation, the MN-free BNC dose-response curve coincided with that of the loss of colony-forming ability, suggesting the potential of the former as a predictive test of cell killing. After Ar irradiation, there was a dissociation between the two effects, especially at high doses: cell death was greater than the frequency of BNC with MN. The inactivation cross-section was 74 microns2; it was 39 microns2 for MN yield. Therefore, the relative biological effectiveness (RBE) was higher for cell killing than for MN yield (0.8 and 0.5, respectively at a Co dose of 3 Gy). The total MN count in BNC followed the same pattern of response as the fraction of BNC with MN.(ABSTRACT TRUNCATED AT 250 WORDS)

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Yield of Strand Breaks as a Function of Scavenger Concentration and LET for SV40 Irradiated with 4 He Ions

Cited by 60 publications

References 24 publications

Reaction rate coefficients of hydroxyl radical-induced DNA single- and α-type double-strand breaks

Reaction rate coefficients of hydroxyl radical-induced DNA single- and α-type double-strand breaks

Scanning force microscopy studies of X-ray-induced double-strand breaks in plasmid DNA

Micronucleus induction and reproductive death in a human cell line exposed to low-energy argon beam

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