Abstract：
:Single crystals of guanine hydrobromide monohydrate, in which the guanine base is protonated at N7, were X-irradiated at 8 and 65 K. Using K-band ESR, ENDOR, and field-swept-ENDOR (FSE) techniques, the crystals were studied between 8 K and room temperature. There was evidence for five different radicals, RI-RV, immediately following irradiation at 8 or 65 K. RI was identified as the O6-protonated anion. It decayed near room temperature with no detectable successor. RII was identified as the N7-deprotonated cation, and decayed near 130 K. RIII is thought to be a ring-opened product formed by C8-N9 bond rupture; upon warming, it decayed at 150 K. RIV is the well-known C8 H-addition radical. These four radicals have been observed previously in the hydrochloride salt of guanine monohydrate. RV is novel, however, with magnetic characteristics consistent with those of the product formed by net OH addition to C5 of the unsaturated C4-C5 bond. It is characterized by four alpha-proton couplings indicating pi-electron spin as follows: 13% at C8; 11% at N7; and 12% at N10. RV decayed between 240 and 255 K with no detectable successor. Upon further warming, very weak resonance lines due to additional, unidentified radicals were observed. A comparison of these results with those obtained from other systems containing N7-protonated guanine bases demonstrates the effect of the environment on the primary radical formation.
journal_name
Radiat Resjournal_title
Radiation researchauthors
Hole EO,Sagstuen E,Nelson WH,Close DMsubject
Has Abstractpub_date
1991-02-01 00:00:00pages
119-28issue
2eissn
0033-7587issn
1938-5404journal_volume
125pub_type
杂志文章abstract：:Clustered damage sites other than double-strand breaks (DSBs) have the potential to contribute to deleterious effects of ionizing radiation, such as cell killing and mutagenesis. In the companion article (Semenenko et al., Radiat. Res. 164, 180-193, 2005), a general Monte Carlo framework to simulate key steps in the b...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/rr3414
更新日期：2005-08-01 00:00:00
abstract：:Telomeres cap the ends of chromosomes, preventing end-to-end fusions and subsequent chromosome instability. Here we used a telomerase knockout model to investigate whether telomerase participates in the processes of DNA break repair by de novo synthesis of telomere repeats at broken chromosome ends (chromosome healing...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/rr3203
更新日期：2004-08-01 00:00:00
abstract：:Hypoadrenocorticism, known as Addison's disease in humans, was diagnosed in six beagles after inhalation of at least 1.7 kBq/g lung of 238PuO2. Histological examination of adrenal gland specimens obtained at necropsy revealed marked adrenal cortical atrophy in all cases. Autoradiographs showed only slight alpha-partic...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1996-12-01 00:00:00
abstract：:Little computational or experimental information is available on site-specific hydroxyl attack probabilities to DNA. In this study, an atomistic stochastic model of OH radical reactions with DNA was developed to compute relative OH attack probabilities at individual deoxyribose hydrogen atoms. A model of the self-comp...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/0033-7587(2002)157[0038:ssoatt]2.0.co;2
更新日期：2002-01-01 00:00:00
abstract：:An analytical expression is developed for calculating the average energy deposited by an ion in a volume with dimensions less than the range of the secondary electrons produced. The expression is obtained by including two additional terms in an energy-restricted linear-energy-transfer equation. The usual energy-restri...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1992-12-01 00:00:00
abstract：:As part of a long-term study of the effects of irradiation during development, prenatal and early neonatal mortality were evaluated for beagles exposed in utero at 8 days postcoitus (dpc), 28 dpc, 55 dpc, or 2 days postpartum. Mean doses used were 0,0.16, or 0.83 Gy. A decrease in whelping rates was observed for femal...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1988-07-01 00:00:00
abstract：:We have manipulated the extracellular Ca2+ concentration (1.8 mM in normal Dulbecco's modified Eagle's medium) to test whether the resulting effect on intracellular free Ca2+ homeostasis was similar in heat-sterilized and nonheated mouse NIH-3T3 cells. The responsiveness of the intracellular free Ca2+ concentration to...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1991-10-01 00:00:00
abstract：:The model of radiation action that is presented relates the surviving fraction of irradiated cells to unrepaired DNA double-strand breaks (DSBs). The following assumptions are made in the model: (i) A DNA fragment created by the induced DSBs may move out of its chromosome (become lost), and the probability of that pro...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1989-06-01 00:00:00
abstract：:In pathogen-free mice, but not standard conventionally housed laboratory rodents, two distinctly different modes of early radiation lethality can be identified by modifying the irradiation technique (total-body versus abdominal irradiation) or by therapeutic intervention such as rescue of total-body-irradiated mice wi...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1989-03-01 00:00:00
abstract：:We previously reported that a priming dose of 0.3 Gy on gestation day 11 significantly increased the rate of living fetuses and reduced the incidence of congenital malformations caused by exposure to 5 Gy X rays on gestation day 12 in ICR mice. In the present study, postnatal development of the live offspring was inve...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1999-08-01 00:00:00
abstract：:Cells from patients with ataxia telangiectasia (AT) are abnormal in their response to irradiation as judged by clonogenic survival and accumulation in G2 phase. The relationship of the results of these two assays, however, is still a matter of controversy. Flow cytometry was used to measure the distribution of cells i...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1994-10-01 00:00:00
abstract：:The Escherichia coli nth gene encodes endonuclease III, which catalyses the glycolytic removal of various oxidized thymine residues from DNA. A truncated version of nth, with the prokaryotic regulatory sequences removed, was ligated into the retrovirus-based vector pZipneoSV(X)1 and transfected into the radiosensitive...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1992-10-01 00:00:00
abstract：:We studied the LET and ion species dependence of the RBE for cell killing to clarify the differences in the biological effects caused by the differences in the track structure that result from the different energy depositions for different ions. Normal human skin fibroblasts were irradiated with heavy-ion beams such a...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/rr3360
更新日期：2005-05-01 00:00:00
abstract：:Late radiation damage to pig skin has been assessed at 104 weeks after exposure to sources of 90Sr/90Y (Emax 2.2 MeV) and 170Tm (Emax 0.9 MeV). Damage was assessed from measurements of dermal thickness in histological sections of irradiated skin and was compared with that of unirradiated skin to establish the relative...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1993-03-01 00:00:00
abstract：:The possibility of a large-scale acute radiation exposure necessitates the development of new methods that could provide rapid individual dose estimates with high sample throughput. The focus of the study was an intercomparison of laboratories' dose-assessment performances using gene expression assays. Lithium-heparin...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR3236.1
更新日期：2013-08-01 00:00:00
abstract：:A subline of a rat mammary carcinoma (MATB 13762), selected for resistance to melphalan, is cross-resistant to other alkylating drugs, to unrelated drugs and to ionizing radiation. The difference in radioresponse between the sensitive wild-type cell line and the melphalan- and radiation-resistant line (MLNr) is relate...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1994-08-01 00:00:00
abstract：:Previously, we described the radiation-induced (RI) 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) effect as the increased MTT metabolization at the intermediate dose region after the irradiation of an MCF-7/6 cell monolayer with an X-ray dose gradient. We wondered if the cell monolayer at the inte...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR3070.1
更新日期：2013-04-01 00:00:00
abstract：:Single crystals of the co-crystalline complex of 1-methyluracil and 9-ethyladenine were X-irradiated and studied using EPR, ENDOR and FSE spectroscopic techniques at 10 K. All together seven radicals were identified, and experimental evidence for at least one more species, as well as for a very low population of radic...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1998-02-01 00:00:00
abstract：:Although conclusive evidence has been obtained for the presence of radiation-induced bystander effects, the mechanisms that trigger and regulate these processes are still largely unknown. The bystander effect may play a critical role in determining the biological effectiveness of low-dose exposures, but questions on h...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/rr3319
更新日期：2005-03-01 00:00:00
abstract：:1-(2-Fluoro-4-iodo-2,4-dideoxy-beta-L-xylopyranosyl)-2-nitroimidazole (FIAZP) has been synthesized and labeled with radioiodine (125I). Radioiodinated FIAZP is one of a series of sugar-coupled 2-nitroimidazoles developed in our laboratory as probes for noninvasive scintigraphic assessment of tumor hypoxia. An in vivo ...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1992-12-01 00:00:00
abstract：:Radiation-induced neurotoxicity is a well-characterized phenomenon. However, the underlying mechanism of this toxicity is poorly understood. In the central nervous system (CNS), excitotoxic mechanisms are implicated in many neurodegenerative disease processes. Pivotal to the excitotoxic pathway is dysfunction of gluta...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR2106.1
更新日期：2010-12-01 00:00:00
abstract：:The effect of ionizing radiation (137Cs) on processing and transport of ribosomal RNA (rRNA) was studied by pulse-labeling HeLa S3 cells with [3H]uridine immediately prior to irradiation. This approach permits kinetic analysis of processing of 45 S rRNA (radiolabeled predominantly prior to irradiation) into its 28 S a...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1990-01-01 00:00:00
abstract：:The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the major protection to astronauts from harmful exposure. Unlike low-LEpsilonTau gamma or X rays, the presence of shielding does not always reduce the radiation risks for en...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR0535.1
更新日期：2006-10-01 00:00:00
abstract：:In this article, we describe recent methodological enhancements and findings from the dose reconstruction component of a study of health risks among U.S. radiologic technologists. An earlier version of the dosimetry published in 2006 used physical and statistical models, literature-reported exposure measurements for t...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR13542.1
更新日期：2014-11-01 00:00:00
abstract：:While the link between risk of leukemia and acute radiation exposure is well established for large doses received acutely, uncertainty remains around the translation of these risk estimates to occupational exposure scenarios where the doses are low and accumulated over time, possibly over many years. We present leukem...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR15358.1
更新日期：2019-11-01 00:00:00
abstract：:We describe a rapid assay to predict intrinsic radiosensitivity of normal tissues based on the radiation-induced cytotoxic response of a number of types of white blood cells. Twenty-four hours after irradiation, leukocytes were prepared for analysis by flow cytometry. Radiation-induced cytotoxicity was characterized b...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1997-01-01 00:00:00
abstract：:The flow cytometry mutation assay is based on detecting mutations in the CD59 gene on human chromosome 11 in CHO A(L) cells with flow cytometry, but the kinetics of mutant expression and the histogram region for mutant selection have not been studied in detail. CHO A(L) cells were analyzed by flow cytometry for CD59 e...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR1276.1
更新日期：2008-11-01 00:00:00
abstract：:Triple negative breast cancer (TNBC) is an aggressive disease with a high risk of recurrence and death. Here, we present a novel strategy to enhance the radiotherapy of TNBC by combining gold nanoparticles (AuNPs) with pentamidine, a clinically approved anti-parasitic agent with anti-cancer properties. The radiosensit...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RR14315.1
更新日期：2016-05-01 00:00:00
abstract：:V79 Chinese hamster cells were irradiated in the presence of different amounts of boric acid with thermal neutrons at the Medical Research Reactor at Brookhaven National Laboratory. From the linear dose-survival curves observed, a D0 value of 66 rad for the 10B(n, alpha) 7Li neutron capture reaction was obtained. No d...
journal_title：Radiation research
pub_type： 杂志文章
doi：
更新日期：1984-05-01 00:00:00
abstract：:Identification of medical countermeasures (MCM) to mitigate radiation damage and/or protect first responders is a compelling unmet medical need. The prostaglandin E2 (PGE2) analog, 16,16 dimethyl-PGE2 (dmPGE2), has shown efficacy as a radioprotectant and radiomitigator that can enhance hematopoiesis and ameliorate int...
journal_title：Radiation research
pub_type： 杂志文章
doi：10.1667/RADE-20-00181.1
更新日期：2020-12-10 00:00:00
