Carcinogenesis Induced by UV and Ionizing Radiation

Averbeck, D.

doi:10.1051/anphys/1997035

Cited by 2 publications

(4 citation statements)

References 62 publications

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“…The transverse-mass spectra of π 0 and η mesons in heavy-ion collisions at SIS energies were recently measured by the TAPS collaboration [36][37][38] where a m T scaling has been observed for both mesons. Such a universal property of the meson spectra at SIS energies has been predicted by the Quark Gluon String Model calculations in Ref.…”

Section: M T Scalingmentioning

confidence: 99%

“…The main knowledge about η production in heavy-ion collisions at BEVALAC/SIS energies is provided by the TAPS collaboration [36][37][38]. However, TAPS measures π 0 and η mesons in a small rapidity interval near y cm whereas the DLS spectrometer covers the forward rapidity region.…”

Section: Introductionmentioning

confidence: 99%

“…in-medium ρ spectral functions as well as hypothetical in-medium modifications of the η mass. To arrive at more stringent conclusions concerning the η contribution we simultaneously analyze the DLS dilepton data [6] together with the new TAPS data [37,38] with respect to m T spectra of π 0 's and η's as well as η photoproduction on nuclei.…”

Section: Introductionmentioning

confidence: 99%

“…The upper part shows the m T spectra for π 0 's (dashed histogram) and η's (solid histogram) for C + C at 1.0 A·GeV in the rapidity interval 0.42 ≤ y ≤ 0.74 and at 2.0 A·GeV for 0.8 ≤ y ≤ 1.08. The experimental data -open circles and solid squares correspond to π 0 and η mesons, respectively -are taken from Ref [37]…”

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confidence: 99%

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Dilepton production and mT-scaling at BEVALAC/SIS energies

et al. 1998

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We present a dynamical study of e + e − production in C + C and Ca + Ca collisions at BEVALAC/SIS energies on the basis of the covariant transport approach HSD employing momentum-dependent ρ-meson spectral functions that include the pion modifications in the nuclear medium as well as the polarization of the ρ-meson due to resonant ρ−N scattering. We find that the experimental data from the DLS collaboration cannot be described within the ρ-meson spectral function approach. A dropping η-mass scenario leads to a good reproduction of the DLS dilepton data, however, violates the m Tscaling of π 0 and η spectra as observed by the TAPS collaboration as well as η photoproduction on nuclei. PACS

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Section: M T Scalingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Dilepton production and mT-scaling at BEVALAC/SIS energies

et al. 1998

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Aqueous Ionization and Electron-Donating Properties of Dinucleotides: Sequence-Specific Electronic Effects on DNA Alkylation

1999

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He I, UV photoelectron data and results from self-consistent-field (SCF) and post-SCF molecular orbital calculations were used to evaluate multiple gas-phase ionization potentials (IPs) of the phosphorylated dinucleotide 5′ pGpAp both isolated and in a cluster with Na + and H 2 O. SCF calculations with a split-valence basis set indicate that the ground-state valence orbital structure of 5′ pGpAp is generally localized on the base, sugar, or phosphate groups and that orbitals in the dinucleotide are similar to orbitals in the model compounds and anion, 1,9-dimethylguanine, 9-methyladenine, 3-hydroxytetrahydrofuran, and H 2 PO 4 -. This correlation parallels that in mononucleotides (Fernando, H.; Papadantonakis, G. A.; Kim, N. S.; LeBreton, P. R. Proc. Natl. Acad. Sci. U.S.A. 1998, 95, 5550-5555; Kim, N. S.; LeBreton, P. R. J. Am. Chem. Soc. 1996, 118, 3694-3707) and permits the correction of SCF ionization potentials using experimental IPs for the model compounds and theoretical IPs from post-SCF calculations on H 2 PO 4 -. A comparison of IPs of 5′ pGpAp, 5′ pGpA, 2′-deoxyguanosine 5′-phosphate (5′-dGMP -), and 2′-deoxyadenosine 5′-phosphate (5′-dAMP -), both isolated and in gas-phase clusters with Na + and H 2 O, indicates that the electrostatic influence of Na + and the anionic phosphate groups is great. IPs decrease significantly as the number of phosphate groups increases. For 5′-dGMP -, 5′ pGpA, and 5′ pGpAp, the lowest adiabatic guanine ionization potentials are 5.2, 3.1, and 1.6 eV, respectively; the lowest phosphate vertical IPs are 5.1, 3.1, and 1.9 eV. Gas-phase IPs were combined with hydration energies obtained with a Langevin dipole relaxation model to evaluate the 22 lowest aqueous ionization energies in 5′ pGpAp as well as ionization energies in the other nucleotides with and without counterions. The electrostatic dependence of the gas-phase IPs on the number of phosphate groups is modulated in aqueous solution. For 5′-dGMP -, 5′ pGpA, and 5′ pGpAp, the aqueous guanine and phosphate ionization energies lie in the ranges 4.2-4.9 eV and 5.5-6.1 eV, respectively. Solvent relaxation similarly modulates Na + electrostatic effects. It also alters the relative energies of ionization events. In the gas phase, the first adiabatic base IP is equal to or larger than the lowest phosphate vertical IP. In water, the base ionization energies are 1.2-1.3 eV smaller than the phosphate ionization energies. Guanine gas-phase π ionization energies in five different B-DNA oligomer models, each containing six stacked base pairs, were compared with site-specific reactivity data for methylation at the guanine N7 and O 6 atoms by the carcinogen, N-methyl-N-nitrosourea (MNU). O 6 methylation is associated with MNU carcinogenesis; N7 methylation is the principal DNA reaction pathway. At both guanine atoms, reactivity increases as the lowest guanine π ionization potential decreases. This is consistent with a description of transition states in which activation barriers are lowered as nucleotide base π polarizability increas...

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Carcinogenesis Induced by UV and Ionizing Radiation

Cited by 2 publications

References 62 publications

Dilepton production and mT-scaling at BEVALAC/SIS energies

Dilepton production and mT-scaling at BEVALAC/SIS energies

Aqueous Ionization and Electron-Donating Properties of Dinucleotides: Sequence-Specific Electronic Effects on DNA Alkylation

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