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Marisa H. G. Medeiros - One of the best experts on this subject based on the ideXlab platform.
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Ultrasensitive Simultaneous Quantification of 1,N2-Etheno-2′-Deoxyguanosine and 1,N2-Propano-2′-Deoxyguanosine in DNA by an Online Liquid Chromatography−Electrospray Tandem Mass Spectrometry Assay
Chemical research in toxicology, 2010Co-Authors: Camila Carrião Machado Garcia, Paolo Di Mascio, Florêncio P. Freitas, Marisa H. G. MedeirosAbstract:Exocyclic DNA adducts produced by exogenous and endogenous compounds are emerging as potential tools to study a variety of human diseases and air pollution exposure. A highly sensitive method involving online reverse-phase high performance liquid chromatography with electrospray tandem mass spectrometry detection in the multiple reaction monitoring mode and employing stable isotope-labeled internal standards was developed for the simultaneous quantification of 1,N2-etheno-2′-Deoxyguanosine (1,N2-edGuo) and 1,N2-propano-2′-Deoxyguanosine (1,N2-propanodGuo) in DNA. This methodology permits direct online quantification of 2′-Deoxyguanosine and ca. 500 amol of adducts in 100 μg of hydrolyzed DNA in the same analysis. Using the newly developed technique, accurate determinations of 1,N2-etheno-2′-Deoxyguanosine and 1,N2-propano-2′-Deoxyguanosine levels in DNA extracts of human cultured cells (4.01 ± 0.32 1,N2-edGuo/108 dGuo and 3.43 ± 0.33 1,N2-propanodGuo/108 dGuo) and rat tissue (liver, 2.47 ± 0.61 1,N2-edGuo...
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Flow injection amperometric detection of 2'-Deoxyguanosine at a ruthenium oxide hexacyanoferrate modified electrode.
Analytical chemistry, 2007Co-Authors: Thiago R.l.c. Paixão, Camila Carrião Machado Garcia, Marisa H. G. Medeiros, Mauro BertottiAbstract:A ruthenium oxide hexacyanoferrate (RuOHCF) modified electrode was developed. Hydrodynamic voltammetry was employed to demonstrate the remarkable electrocatalytic activity toward the oxidation of 2'-Deoxyguanosine. The RuOHCF modified electrode was used as amperometric detector for 2'-Deoxyguanosine determination in a FIA apparatus. The influence of various experimental conditions was explored for optimum analytical performance, and at these experimental conditions, the method exhibited a linear response range to 2'-Deoxyguanosine extending from 3.8 to 252 micromol L(-1) with detection limit of 94 nmol L(-1). Applications in DNA samples were examined, and the results for determination of 2'-Deoxyguanosine were in good agreement with those obtained by HPLC analysis. Studies on the kinetics of the in vitro consumption of 2'-Deoxyguanosine by acetaldehyde were also performed.
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Singlet oxygen oxidation of 2′-Deoxyguanosine. Formation and mechanistic insights
Tetrahedron, 2006Co-Authors: Jean-luc Ravanat, Paolo Di Mascio, Marisa H. G. Medeiros, G. Martinez, Jean CadetAbstract:Abstract Emphasis was placed in this work on the delineation of mechanistic aspects of the singlet oxygen-mediated oxidation reactions of 2′-Deoxyguanosine 1 used as a DNA model compound in aerated aqueous solution. For this purpose a thermolabile naphthalene endoperoxide derivative was used allowing the generation of [ 18 O]-labeled singlet oxygen for dedicated mechanistic studies. The analysis and characterization of the oxidized nucleosides of the 1 O 2 reactions were achieved on the basis of accurate HPLC–tandem mass spectrometry measurements. Thus it was found that primary oxidation products include, in addition to the previously identified 8-oxo-7,8-dihydro-2′-Deoxyguanosine 5 and the two diastereomers of spiroiminodihydantoin 8 , two relatively minor nucleosides, namely the two diastereomers of 4-hydroxy-8-oxo-4,8-dihydro-2′-Deoxyguanosine 9 .
Jean Cadet - One of the best experts on this subject based on the ideXlab platform.
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Singlet oxygen oxidation of 2′-Deoxyguanosine. Formation and mechanistic insights
Tetrahedron, 2006Co-Authors: Jean-luc Ravanat, Paolo Di Mascio, Marisa H. G. Medeiros, G. Martinez, Jean CadetAbstract:Abstract Emphasis was placed in this work on the delineation of mechanistic aspects of the singlet oxygen-mediated oxidation reactions of 2′-Deoxyguanosine 1 used as a DNA model compound in aerated aqueous solution. For this purpose a thermolabile naphthalene endoperoxide derivative was used allowing the generation of [ 18 O]-labeled singlet oxygen for dedicated mechanistic studies. The analysis and characterization of the oxidized nucleosides of the 1 O 2 reactions were achieved on the basis of accurate HPLC–tandem mass spectrometry measurements. Thus it was found that primary oxidation products include, in addition to the previously identified 8-oxo-7,8-dihydro-2′-Deoxyguanosine 5 and the two diastereomers of spiroiminodihydantoin 8 , two relatively minor nucleosides, namely the two diastereomers of 4-hydroxy-8-oxo-4,8-dihydro-2′-Deoxyguanosine 9 .
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REACTION OF SINGLET OXYGEN WITH 2'-Deoxyguanosine AND DNA. ISOLATION AND CHARACTERIZATION OF THE MAIN OXIDATION PRODUCTS
Chemical research in toxicology, 1995Co-Authors: Jean-luc Ravanat, Jean CadetAbstract:The reaction of singlet molecular oxygen with 2'-Deoxyguanosine and DNA was studied. Emphasis was placed on the identification and characterization of the main methylene blue mediated type II (singlet oxygen) oxidation products of 2'-Deoxyguanosine and its corresponding 3',5'-di-O-acetylated derivative. Two major oxidation products of 2'-Deoxyguanosine were isolated and characterized by mass spectrometry analysis and extensive 1H and 13C NMR measurements as the two 4R* and 4S* diastereomers of 4,8-dihydro-4-hydroxy-8-oxo-2'-Deoxyguanosine. The addition of 1O2 was also found to occur to the base moiety of the corresponding 3',5'-di-O-acetylated derivative. Methylene blue mediated photosensitization of 2'-Deoxyguanosine led also to the production of 7,8-dihydro-8-oxo-2'-Deoxyguanosine, but in a relatively lower yield with respect to the two above diastereomers. The participation of singlet oxygen in the mechanism of formation of these oxidation products was confirmed. A reasonable mechanism involving the transient formation of an unstable endoperoxide produced through a Diels-Alder 1,4-cycloaddition of singlet oxygen to the purine ring is suggested. Quantitative analysis allowed us to demonstrate that the two diastereomers of 4,8-dihydro-4-hydroxy-8-oxo-2'-Deoxyguanosine are the main singlet oxygen oxidation products of the guanine moiety within nucleosides, whereas 7,8-dihydro-8-oxoguanine was found to be the major 1O2 oxidation product of guanine in double-stranded DNA.
Ellen R. Mably - One of the best experts on this subject based on the ideXlab platform.
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Secondary loss of Deoxyguanosine kinase activity in purine nucleoside phosphorylase deficient mice.
Biochimica et biophysica acta, 1994Co-Authors: Floyd F. Snyder, Jack P. Jenuth, Jocelyn E. Dilay, Ernest Fung, Therese Lightfoot, Ellen R. MablyAbstract:The T-cell immunodeficiency associated with purine nucleoside phosphorylase (PNP) deficiency in man is believed to be due to the accumulation of dGTP which may be preferentially formed from Deoxyguanosine in T-lymphocytes or their precursor cells. We found no evidence for dGTP accumulation in thymocytes or spleen leucocytes, < 1 nmol/10(9) cells, nor in erythrocytes, < 0.05 nmol/10(9) cells, of the B6-NPE- or B6-NPF PNP-deficient mice strains. There were no changes in purine or pyrimidine ribonucleotide pools. As these mice had been previously shown to excrete PNP nucleoside substrates, we examined the metabolism of Deoxyguanosine. Deoxyguanosine kinase activity as compared to control mice was 6 to 52% for the B6-NPE mutant, 2 to 22% for the B6-NPF mutant. Fractionation of erythrocyte and liver lysates from the F mutation and the background strain, C57BL/6J, by anion exchange chromatography confirmed the secondary deficiency of Deoxyguanosine kinase and demonstrated that this activity was distinct from adenosine kinase and two major peaks of deoxycytidine kinase activity. Mouse PNP, expressed and purified as a fusion protein, did not show evidence of being bifunctional and having Deoxyguanosine kinase activity. Metabolic modelling revealed that the ratio of Deoxyguanosine phosphorylation versus phosphorolysis was < 0.06 in control mice, and < or = 0.3 in lymphocytes of PNP-deficient mice. Were Deoxyguanosine kinase not reduced in the PNP-deficient mice, all tissues of the B6-NPF mutant would preferentially phosphorylate Deoxyguanosine at low substrate concentrations.
Robert J. Turesky - One of the best experts on this subject based on the ideXlab platform.
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biomonitoring dna adducts of cooked meat carcinogens in human prostate by nano liquid chromatography high resolution tandem mass spectrometry identification of 2 amino 1 methyl 6 phenylimidazo 4 5 b pyridine dna adduct
Analytical Chemistry, 2016Co-Authors: Shun Xiao, Jingshu Guo, Byeong Hwa Yun, Peter W. Villalta, Suprita Krishna, Resha Tejpaul, Paari Murugan, Christopher J. Weight, Robert J. TureskyAbstract:Epidemiologic studies have reported an association between frequent consumption of well-done cooked meats and prostate cancer risk. However, unambiguous physiochemical markers of DNA damage from carcinogens derived from cooked meats, such as DNA adducts, have not been identified in human samples to support this paradigm. We have developed a highly sensitive nano-LC-Orbitrap MSn method to measure DNA adducts of several carcinogens originating from well-done cooked meats, tobacco smoke, and environmental pollution, including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), benzo[a]pyrene (B[a]P), and 4-aminobiphenyl (4-ABP). The limit of quantification (LOQ) of the major Deoxyguanosine (dG) adducts of these carcinogens ranged between 1.3 and 2.2 adducts per 109 nucleotides per 2.5 μg of DNA assayed. The DNA adduct of PhIP, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) was identified in 11 out of 35 patients, at le...
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Multiclass Carcinogenic DNA Adduct Quantification in Formalin-Fixed Paraffin-Embedded Tissues by Ultraperformance Liquid Chromatography–Tandem Mass Spectrometry
2016Co-Authors: Jingshu Guo, Byeong Hwa Yun, Pramod Upadhyaya, Lihua Yao, Sesha Krishnamachari, Thomas A. Rosenquist, Arthur P. Grollman, Robert J. TureskyAbstract:DNA adducts are a measure of internal exposure to genotoxicants and an important biomarker for human risk assessment. However, the employment of DNA adducts as biomarkers in human studies is often restricted because fresh-frozen tissues are not available. In contrast, formalin-fixed paraffin-embedded (FFPE) tissues with clinical diagnosis are readily accessible. Recently, our laboratory reported that DNA adducts of aristolochic acid, a carcinogenic component of Aristolochia herbs used in traditional Chinese medicines worldwide, can be recovered quantitatively from FFPE tissues. In this study, we have evaluated the efficacy of our method for retrieval of DNA adducts from archived tissue by measuring DNA adducts derived from four other classes of human carcinogens: polycyclic aromatic hydrocarbons (PAHs), aromatic amines, heterocyclic aromatic amines (HAAs), and N-nitroso compounds (NOCs). Deoxyguanosine (dG) adducts of the PAH benzo[a]pyrene (B[a]P), 10-(deoxyguanosin-N2-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (dG-N2–B[a]PDE); the aromatic amine 4-aminobiphenyl (4-ABP), N-(deoxyguanosin-8-yl)–4-aminobiphenyl (dG-C8–4-ABP); the HAA 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), N-(deoxyguanosin-8-yl)-PhIP (dG-C8–PhIP); and the dG adducts of the NOC 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), O6-methyl-dG (O6-Me–dG) and O6-pyridyloxobutyl-dG (O6-POB–dG), formed in liver, lung, bladder, pancreas, or colon were recovered in comparable yields from fresh-frozen and FFPE preserved tissues of rodents treated with the procarcinogens. Quantification was achieved by ultraperformance liquid chromatography coupled with electrospray ionization ion-trap multistage mass spectrometry (UPLC/ESI-IT-MS3). These advancements in the technology of DNA adduct retrieval from FFPE tissue clear the way for use of archived pathology samples in molecular epidemiology studies designed to assess the causal role of exposure to hazardous chemicals with cancer risk
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Biomonitoring DNA Adducts of Cooked Meat Carcinogens in Human Prostate by Nano Liquid Chromatography–High Resolution Tandem Mass Spectrometry: Identification of 2‑Amino-1-methyl-6-phenylimidazo[4,5‑b]pyridine DNA Adduct
2016Co-Authors: Shun Xiao, Jingshu Guo, Byeong Hwa Yun, Peter W. Villalta, Suprita Krishna, Resha Tejpaul, Paari Murugan, Christopher J. Weight, Robert J. TureskyAbstract:Epidemiologic studies have reported an association between frequent consumption of well-done cooked meats and prostate cancer risk. However, unambiguous physiochemical markers of DNA damage from carcinogens derived from cooked meats, such as DNA adducts, have not been identified in human samples to support this paradigm. We have developed a highly sensitive nano-LC-Orbitrap MSn method to measure DNA adducts of several carcinogens originating from well-done cooked meats, tobacco smoke, and environmental pollution, including 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), benzo[a]pyrene (B[a]P), and 4-aminobiphenyl (4-ABP). The limit of quantification (LOQ) of the major Deoxyguanosine (dG) adducts of these carcinogens ranged between 1.3 and 2.2 adducts per 109 nucleotides per 2.5 μg of DNA assayed. The DNA adduct of PhIP, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) was identified in 11 out of 35 patients, at levels ranging from 2 to 120 adducts per 109 nucleotides. The dG-C8 adducts of AαC and MeIQx, and the B[a]P adduct, 10-(deoxyguanosin-N2-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (dG-N2-B[a]PDE) were not detected in any specimen, whereas N-(deoxyguanosin-8-yl)-4-ABP (dG-C8-4-ABP) was identified in one subject (30 adducts per 109 nucleotides). PhIP–DNA adducts also were recovered quantitatively from formalin fixed paraffin embedded (FFPE) tissues, signifying FFPE tissues can serve as biospecimens for carcinogen DNA adduct biomarker research. Our biomarker data provide support to the epidemiological observations implicating PhIP, one of the most mass-abundant heterocyclic aromatic amines formed in well-done cooked meats, as a DNA-damaging agent that may contribute to the etiology of prostate cancer
James F. Hatcher - One of the best experts on this subject based on the ideXlab platform.
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Identification of N-(deoxyguanosin-8-yl)-4-azobiphenyl by 32P-postlabeling analyses of DNA in human uroepithelial cells exposed to proximate metabolites of the environmental carcinogen 4-aminobiphenyl
Environmental and molecular mutagenesis, 2002Co-Authors: James F. Hatcher, Santhanam SwaminathanAbstract:DNA adducts formed in human uroepithelial cells (HUC) following exposure to N-hydroxy-4-aminobiphenyl (N-OH-ABP), the proximate metabolite of the human bladder carcinogen 4-aminobiphenyl (ABP), were analyzed by the 32P-postlabeling method. Two adducts detected by 32P-postlabeling were previously identified as the 3′,5′-bisphospho derivatives of N-(deoxyguanosin-8-yl)-4-aminobiphenyl (dG-C8-ABP) and N-(deoxyadenosin-8-yl)-4-aminobiphenyl (dA-C8-ABP) (Frederickson S et al. [1992] Carcinogenesis 13: 955–961; Hatcher and Swaminathan [1995b] Carcinogenesis 16: 295–301). In contrast to the dG-C8-ABP adduct, which was 3′-dephosphorylated by nuclease P1, dA-C8-ABP was resistant to nuclease P1, thus providing an enrichment step before postlabeling. Autoradiography of the two-dimensional thin-layer chromatogram of the postlabeled products obtained following nuclease P1 digestion revealed several minor adducts, one of which has been identified in the present study. Postlabeling analyses following nuclease P1 digestion of the products obtained from the reaction of N-acetoxy-4-aminobiphenyl with Deoxyguanosine-3′-monophosphate (dGp) demonstrated the presence of this minor adduct. The 3′-monophosphate derivative of the adduct was subsequently chromatographically purified and subjected to spectroscopic analyses. Based on proton NMR and mass spectroscopic analyses of the synthetic product, the chemical structure of the adduct has been identified as N-(deoxyguanosin-N2-yl)-4-azobiphenyl (dG-NN-ABP). 32P-Postlabeling analysis of the nuclease P1–enriched DNA hydrolysate of HUCs treated with N-OH-ABP or N-hydroxy-4-acetylaminobiphenyl (N-OH-AABP) showed the presence of the dG-NN-ABP adduct. It was also detected in calf thymus DNA incubated with HUC cytosol and N-OH-ABP in the presence of acetyl-CoA, or incubated with HUC microsomes and N-OH-AABP. These results demonstrate that in the target cells for ABP carcinogenesis in vivo, N-OH-ABP and N-OH-AABP are bioactivated by acyltransferases to reactive arylnitrenium ions that covalently interact at the N2 position of Deoxyguanosine in DNA. Environ. Mol. Mutagen. 39:314–322, 2002. © 2002 Wiley-Liss, Inc.
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Identification of new DNA adducts in human bladder epithelia exposed to the proximate metabolite of 4-aminobiphenyl using 32P-postlabeling method
Chemico-biological interactions, 2002Co-Authors: Santhanam Swaminathan, James F. HatcherAbstract:The DNA adducts were analyzed by 32P-postlabeling method following exposure of human uroepithelial cells (HUC) to N-hydroxy-4-aminobiphenyl (N-OH-ABP), the proximate metabolite of the human bladder carcinogen 4-aminobiphenyl (ABP). TLC of the postlabeled products on the first dimension revealed several products, the majority of which stayed close to the origin and were earlier identified as the 3',5' -bisphospho derivatives of N-(deoxyguanosin-8-yl)-4-aminobiphenyl and N-(deoxyadenosin-8-yl)-4-aminobiphenyl (Carcinogenesis 13 (1993) 955; Carcinogenesis 16 (1995) 295). Here we report characterization of two additional adducts that amounted to less than 5% of the total adducts. Autoradiography of D1 chromatogram of the postlabeled products of calf thymus DNA chemically interacted with N-OH-ABP under acidic conditions revealed two adducts, #1 and #2, with R(f) values of about 0.2 and 0.3, respectively. Two adducts with D1 thin layer chromatographic properties similar to those of adducts #1 and #2 were obtained on postlabeling analyses of products generated by chemical interaction of N-acetoxy-4-aminobiphenyl (N-OAc-ABP) with Deoxyguanosine-3' -monophosphate (dGp). Based on proton NMR and mass spectroscopic analyses of the synthetic products derived from N-OAc-ABP, the chemical structures of adducts #1 and #2 have been identified as 3-(deoxyguanosin-N(2)-yl)-4-aminobiphenyl, and N-(deoxyguanosin-N(2)-yl)-4-aminobiphenyl, respectively. Both of these adducts were insensitive to digestion with nuclease P1. 32P-Postlabeling analysis of the nuclease P1 enriched DNA hydrolysate of HUC cells treated with N-OH-ABP showed the presence of adduct #2 but not adduct #1. Adduct #2 was also detected in calf thymus DNA incubated with HUC cytosol and N-OH-ABP in the presence of acetyl CoA. These results suggest that in the target cells for ABP carcinogenesis in vivo, N-OH-ABP is bioactivated by acetyl CoA-dependent acyltransferases to reactive arylnitrenium ions that covalently interact at N(2)-position of Deoxyguanosine in DNA.