Abstract:
:Electron transfer to 5-bromouracil (5-BrU) from nucleobase (N) electron adducts (and their protonated forms) has been studied by product analysis and pulse radiolysis. When an electron is transferred to 5-BrU, the ensuing 5-BrU radical anion rapidly loses a bromide ion; the uracilyl radical thus formed reacts with added t-butanol, yielding uracil. From the uracil yields measured as the function of [N]/[5-BrU] after gamma-radiolysis of Ar-saturated solutions it is concluded that thymine and adenine electron adducts and their heteroatomprotonated forms transfer electrons quantitatively to 5-BrU. Like the electron adduct of adenine, those of cytosine and guanine are rapidly protonated by water. The (protonated) electron adduct of guanine does not transfer an electron to 5-BrU, and in the case of the (protonated) cytosine electron adduct only partial electron transfer is observed. The results can be modelled if the protonated electron adduct (protonated at N(3) or at the amino group) of cytosine, CH., which can transfer its electron to 5-BrU (k approximately 2 x 10(7) dm3 mol-1 s-1) is transformed in a slow tautomerization reaction (k approximately 2.5 x +/- 10(3) s-1) into another form C'H. (possibly protonated at C(6) or C(5)) which does not transfer an electron to 5-BrU. There is also electron transfer from the electron adduct of thymine to cytosine and guanine which serve as electron sinks. The rate constant of electron transfer from the thymine electron adduct to cytosine is about 250 times greater than that of the reverse reaction. The heteroatom-protonated electron-adduct of thymidine transfers an electron to 5-BrU more slowly (k = 2.3 x 10(7) dm3 mol-1 s-1) than the electron-adduct itself (k = 7.2 x 10(8) dm3 mol-1 s-1). Phosphate buffer-induced protonation of the electron-adduct of thymine at carbon (C(6)) prevents electron transfer to 5-BrU. Such phosphate catalysis is also observed as an intramolecular process (k approximately 2 x 10(4) s-1) with thymidine-5'-phosphate but not with the 3'-phosphate. Phosphate-induced protonation at carbon also reduces transfer efficiency for the electron adducts of dinucleoside phosphates such as dTpdT and dTpdA. The data raise the question whether in DNA the guanine moiety may act as the ultimate sink of the electron in competition with other processes such as protonation at C(6) of the thymine electron adduct.
journal_name
Int J Radiat Bioljournal_title
International journal of radiation biologyauthors
Nese C,Yuan Z,Schuchmann MN,Von Sonntag Cdoi
10.1080/09553009214552451subject
Has Abstractpub_date
1992-11-01 00:00:00pages
527-41issue
5eissn
0955-3002issn
1362-3095pii
DP6XNTP6F0YRQ93Ujournal_volume
62pub_type
杂志文章abstract:PURPOSE:Ionizing radiation causes various types of DNA damage e.g. single strand breaks (SSB) and double strand breaks (DSB), whereby the SSB/DSB ratio is shifted toward the DSB with increasing LET. For the DNA-incorporated Auger electron emitter Iodine-125 a SSB/DSB ratio of 5.4:1 is calculated based on computer simul...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553002.2020.1851059
更新日期:2020-12-03 00:00:00
abstract::Objective: To quantify DNA damage in patients undergoing non-contrast and contrast-enhanced 18F-FDG PET/CT whole body positron emission tomography/computed tomography (WB PET/CT) investigations using comet assay technique and micronucleus assay, and to study the effect of other baseline parameters of patients on DNA d...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553002.2019.1577569
更新日期:2019-06-01 00:00:00
abstract:PURPOSE:Zearalenone is a potent estrogenic metabolite produced by some Fusarium and Gibberella species. Therefore, the aim of this study was to determine the accumulation of Technetium-[99m]-labeled zearalenone in mice organs as well as to study the protective effect of Lactobacillus plantarum. MATERIALS AND METHODS:T...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553002.2019.1524990
更新日期:2018-12-01 00:00:00
abstract:PURPOSE:In order to understand the molecular mechanism of nucleobase damage caused by ultrasoft X-ray irradiation, guanine radicals have been studied using an X-band EPR (electron paramagnetic resonance) spectrometer installed in a synchrotron soft X-ray beamline. MATERIALS AND METHODS:Guanine pellets were irradiated ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553000400017689
更新日期:2004-11-01 00:00:00
abstract:PURPOSE:To propose an improved version of RADACK, a stochastic simulation of radiolytic attack on DNA, that takes into account the reactivity of each amino acid of a specifically bound protein with hydroxyl radicals. To apply it to the natural lactose operator-repressor complex taking advantage of recently reported str...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/0955300031000137788
更新日期:2003-06-01 00:00:00
abstract::Swiss albino mice (7-8 weeks old) were irradiated with different doses (0-25 Gy) of gamma-radiation at a dose-rate of 0.05 Gy/s. The specific activities of glyoxalase I (GI) and glyoxalase II (GII) were determined in the spleen and liver immediately and on the 3rd and 6th day postirradiation. The results indicate that...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553009314550301
更新日期:1993-02-01 00:00:00
abstract::DNA double-strand break (dsb) induction in diploid yeast was measured by neutral sucrose sedimentation after exposure to very heavy ions with values of linear energy transfer (LET) ranging from about 300 to 11500 ke V/microns. Linear fluence dependencies were found in all cases from which dsb production cross-sections...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553009214552121
更新日期:1992-09-01 00:00:00
abstract::Purpose: A study is presented of the irradiation of cancerous cervical cell line HeLa loaded with a platinum salt, betamethasone and deoxyglucose. The presence of the platinum increases the free-radical concentration and augments the cell death rate, whereas betamethasone or deoxyglucose induces radiosensitization by ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553002.2020.1721594
更新日期:2020-05-01 00:00:00
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journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/095530096145427
更新日期:1996-06-01 00:00:00
abstract:PURPOSE:To investigate whether mobile phone radiation might affect snail nociception, employing radiofrequency (RF) electromagnetic fields (EMF) which, to our knowledge, have hitherto not been studied in a snail model. Exposure to extremely low frequency (ELF) magnetic fields has however been shown to significantly aff...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.3109/09553002.2012.644257
更新日期:2012-03-01 00:00:00
abstract:PURPOSE:As the most recent epidemiological studies provide no definite conclusions about the effects of 50/60 Hz magnetic fields (MFs) on the incidence of leukaemia in humans, animal models in a well-controlled environment are useful for evaluating the possibility of an association between MFs and leukaemia. The presen...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553000050029011
更新日期:2000-06-01 00:00:00
abstract:PURPOSE:To obtain compounds that will effectively reduce the fixation of uranium in its main target organs: bone and kidney. There is an urgent need for a chelating agent that is suitable and available for human use. MATERIALS AND METHODS:The efficacy of ethane-1-hydroxy-1,1-bisphosphonate (EHBP), already in use as a ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/095530099139331
更新日期:1999-11-01 00:00:00
abstract::Purpose: The key to increasing our understanding of low dose effects of ionizing radiation is cooperation and communication between research organizations around the world. The purpose of this article is to describe the Electric Power Research Institute (EPRI) program for such cooperation. Materials and methods: EPRI ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553002.2019.1569770
更新日期:2019-10-01 00:00:00
abstract::The repair activity of verbascoside (VER), isolated from Pedicularis spicata, towards the oxidizing hydroxyl radical adduct of dGMP and its reaction mechanism were studied using pulse radiolysis. Upon pulse radiolysis of nitrous oxide saturated aqueous solution of 2'-deoxyguanosine-5'-monophosphate (dGMP) and VER, it ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/095530096145779
更新日期:1996-04-01 00:00:00
abstract::237Np nitrate was injected intravenously into 4-week-old (young) and 10-12-week-old (adult) female albino Sprague-Dawley rats. The amounts given were 52 (young), 5.2 (adult) and 26 kBq kg-1 body weight (adult). The microscopic distribution in the femur and the lumbar vertebrae was studied. Initially, neptunium was dis...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553009314550511
更新日期:1993-03-01 00:00:00
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journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553008814551961
更新日期:1988-10-01 00:00:00
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journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553002.2016.1206235
更新日期:2016-10-01 00:00:00
abstract:PURPOSE:Many strategies have been investigated to exclude the several side-effects of pharmacological or invasive treatments. Non-invasive pulsed magnetic field (PMF) treatment with no toxicity or side-effects can be an alternative to pharmacologic treatments. The purpose of this study was, therefore, to investigate th...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.3109/09553002.2013.835501
更新日期:2014-01-01 00:00:00
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journal_title:International journal of radiation biology
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doi:10.1080/0955300031000076894
更新日期:2003-03-01 00:00:00
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journal_title:International journal of radiation biology
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doi:10.1080/09553002.2017.1304668
更新日期:2017-07-01 00:00:00
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更新日期:1990-08-01 00:00:00
abstract:PURPOSE:Caffeine (1,3,7-trimethyl xanthine), a dietary component, has been shown to have widely varying effects on DNA damage induced by UV and ionizing radiation, depending upon pre- or post-irradiation administration and its concentration. Caffeine administered post-UV irradiation is known to inhibit enzymatic repair...
journal_title:International journal of radiation biology
pub_type: 杂志文章
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更新日期:2001-05-01 00:00:00
abstract:PURPOSE:Genotoxic effects have been considered the gold standard to determine if an environmental factor is a carcinogen, but the currently available data for extremely low frequency time-varying magnetic fields (ELF-MF) remain controversial. As an environmental stimulus, the effect of ELF-MF on cellular DNA may be sub...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.3109/09553002.2014.887866
更新日期:2014-04-01 00:00:00
abstract:PURPOSE:A key enzyme of polyamine catabolism, spermidine/spermine N(1)-acetyltransferase (SSAT), is responsive to antiproliferative agents. The role of SSAT in cellular responses to X-ray irradiation was examined. MATERIALS AND METHODS:Exponentially growing HeLa S3 cells were irradiated by X-rays, and mRNA levels for ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553000410001695886
更新日期:2004-05-01 00:00:00
abstract::We have examined the timing of gamma-irradiation-induced death in relation to cell cycle progression using a panel of mouse lymphoid or myeloid cell lines. Death was found to occur immediately after irradiation ('rapid interphase' death), or after arrest in G2 phase ('delayed interphase' death). In part II of this ser...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553009414550261
更新日期:1994-02-01 00:00:00
abstract:PURPOSE:Design of cancer radiotherapy protocol to reduce radiation dose and increase treatment efficacy in Lewis lung cancer (LLC) model. METHODS:C57BL/6J mice subcutaneously implanted with LLC were treated by conventional radiotherapy (2Gy x 6) combined with LDWBI (low dose whole-body irradiation; the second, third, ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553000801902133
更新日期:2008-03-01 00:00:00
abstract:PURPOSE:To construct a quantitative model of the radiation-induced bystander effect based on diffusion-type spreading of bystander signal communication between the hit and non-hit cells. Cell inactivation and induced oncogenic transformation by broad- and microbeam irradiation systems are considered. MATERIALS AND MET...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:
更新日期:2003-01-01 00:00:00
abstract::We used a cell sorter assay to evaluate the efficacy of the hypoxic cell sensitizer etanidazole over 3-4 logs of cell inactivation, with particular attention to the clinically relevant low-dose survival region. Analysis of the radiation responses in a panel of six human tumour cell lines under conditions of hypoxia an...
journal_title:International journal of radiation biology
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doi:10.1080/095530096144617
更新日期:1996-12-01 00:00:00
abstract:PURPOSE:The aim was to evaluate the utility of multiple blood-protein biomarkers for early-response assessment of radiation exposure using a murine radiation model system. MATERIAL AND METHODS:BALB/c male mice (8-10 weeks old) were exposed to whole-body 60Co gamma-rays (10 cGy min(-1)) over a broad dose range (0-7 Gy)...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:
更新日期:2009-01-01 00:00:00
abstract:PURPOSE:To carry out a comparative study on potential cytogenetic fingerprints for radiation LET in human metaphase lymphocytes. MATERIALS AND METHOD:Human lymphocytes were irradiated in vitro with 3.0 Gy 60Co gamma-rays, 0.9 Gy 3H beta-rays or 0.2 Gy 2.7 Mev neutrons. Detailed chromosome aberrations were analysed by ...
journal_title:International journal of radiation biology
pub_type: 杂志文章
doi:10.1080/09553000050201073
更新日期:2000-12-01 00:00:00