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  • 1. Chadt, J
    et al.
    Sykora, D
    Nilsson, Robert
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Monitoring of dimethyl sulphate-induced N3-methyladenine, N7-methylguanine and O6-methylguanine DNA adducts using reversed-phase high performance liquid chromatography and mass spectrometry 2008In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 867, p. 43-48Article in journal (Refereed)
    Abstract [en]

    This work describes the determination of N3-methyladenine, N7-methylguanine and O6-methylguanine adducts in dimethyl sulphate-treated salmon-testes DNA employing reversed-phase high performance liquid chromatography (RP-HPLC) with UV–vis detection, followed by mass-spectrometric verification using electrospray ionisation in positive mode ESI(+). Within validation parameters, accuracy, precision, calibration parameters, limit of detection (LOD) and quantitation (LOQ) as well as stability of standard stock solutions were tested and presented for UV/vis detection. The limit of detection (LOD) was found to be 0.1 ng/mL for N3-methyladenine and 0.2 ng/mL for both N7-methylguanine and O6-methylguanine (S/N = 3). The limit of quantitation (LOQ) was found to be 0.5 ng/mL for all measured compounds, (S/N = 10). Quantitative results were obtained for each substance based on eight-point calibration. Intra- and inter-day precisions were within 1.73–6.96 and 2.26–7.58%, respectively, and correlation coefficients of calibration curves (R2) ranged from 0.9992 to 0.9997. Relative proportion of N7-methylguanine was accounted for 61.53 ± 2.97% (R.S.D. = 4.8), N3-methyladenine for 38.19 ± 2.99% (R.S.D. = 9.6) and O6-methylguanine for 0.29 ± 0.02% (R.S.D. = 5.1), respectively. The application of the above-mentioned techniques provides a valuable contribution for simultaneous determination of methylated DNA adducts, and may represent a suitable approach for similar monitoring/screening studies.

  • 2. Gradecka-Meesters, Dobroslawa
    et al.
    Palus, Jadwiga
    Prochazka, Gabriela
    Segerback, Dan
    Dziubaltowska, Elzbieta
    Kotova, Natalia
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Jenssen, Dag
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Arkusz, Joanna
    Lundin, Cecilia
    Vikstrom, Elisabet
    Rydzynski, Konrad
    Nilsson, Robert
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Stepnik, Maciej
    Assessment of the protective effects of selected dietary anticarcinogens against DNA damage and cytogenetic effects induced by benzo[a]pyrene in C57BL/6J mice2011In: Food and Chemical Toxicology, ISSN 0278-6915, E-ISSN 1873-6351, Vol. 49, no 8, p. 1674-1683Article in journal (Refereed)
    Abstract [en]

    The protective action in C57BL/6J mice from orally administered ellagic acid (EA), benzyl isothiocyanate (BITC), an extract of epigallocatechins (Tegreen (R)) as well as chlorophyllin (CHL) against benzo[a]pyrene (B[a]P)-induced DNA damage and cytogenetic effects was investigated. In pilot experiment the comet assay indicated protective effects for all compounds, while such activity was confined to EA and CH with respect to B[a]P-DNA adducts and micronuclei. EA and CH were chosen for the main study where the levels of DNA adducts in liver after injection of 30 mg B[a]P/kg b.w. did not differ from those found for animals exposed to B[a]P and treated with the protective substances. In leukocytes no significant protective effect of CHL was detected while a 2-fold increase of adduct concentrations was observed after co-administration of EA. In the comet assay CHL or EA caused a 3-fold decrease of SSB, and a 2-fold decrease of FPG sites in comparison to animals treated with B[a]P. CHL or EA showed a significant protective effect against B[a]P-induced MN in polychromatic erythrocytes in bone marrow. In contrast, flow cytometry measurements in peripheral blood indicated the MN frequency after treatment with CHL or EA almost twice as high as that recorded for B[a]P alone.

  • 3.
    Helleday, T
    et al.
    Stockholm University.
    Nilsson, R
    Stockholm University.
    Jenssen, D
    Stockholm University.
    Arsenic[III] and heavy metal ions induce intrachromosomal homologous recombination in the hprt gene of V79 Chinese hamster cells.2000In: Environ Mol Mutagen, ISSN 0893-6692, Vol. 35, no 2, p. 114-22Article in journal (Refereed)
  • 4.
    Johansson, Fredrik
    et al.
    Stockholm University.
    Allkvist, Annika
    Erixon, Klaus
    Stockholm University.
    Malmvärn, Anna
    Stockholm University.
    Nilsson, Robert
    Stockholm University.
    Bergman, Ake
    Helleday, Thomas
    Stockholm University.
    Jenssen, Dag
    Stockholm University.
    Screening for genotoxicity using the DRAG assay: investigation of halogenated environmental contaminants.2004In: Mutat Res, ISSN 0027-5107, Vol. 563, no 1, p. 35-47Article in journal (Refereed)
  • 5. Lewinska, D
    et al.
    Palus, J
    Stepnik, M
    Dziubaltowska, E
    Beck, J
    Rydzynski, K
    Natarajan, A.T.
    Nilsson, Robert
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Micronucleus frequency in peripheral blood lymphocytes and buccal mucosa cells of copper smelter workers, with special regard to arsenic exposure2007In: International Archives of Occupational and Environmental Health, ISSN 0340-0131, E-ISSN 1432-1246, Vol. 80, no 5, p. 371-380Article in journal (Refereed)
    Abstract [en]

    Occupational exposure in copper smelters may produce various adverse health effects including cancer which, according to available epidemiologic data, is associated mainly with exposure to arsenic. Despite a number of well-documented studies reporting an increased risk of cancer among copper smelters workers, the data on genotoxic effects in this industry are scarce. In view of the above, an assessment of micronuclei (MN) frequency in peripheral blood lymphocytes and buccal epithelial cells from copper smelter workers was undertaken. Additionally, the clastogenic/aneugenic effect in lymphocytes was assessed with the fluorescence in situ hybridization (FISH). The study was conducted in three copper smelters in southwestern Poland. The subjects (n = 72) were enrolled among male workers at departments where As concentration in the air was up to at 80 μg/m3. Exposure was assessed by measurement of arsenic concentration in urine and toenail samples. The control group (n = 83) was recruited from healthy male individuals living in central Poland who did not report any exposure to known genotoxins. The results of our study showed a significant increase in MN frequency in peripheral blood lymphocytes and in buccal epithelial cells of smelter workers, compared to the controls (7.96 ± 4.28 vs. 3.47 ± 1.70 and 0.98 ± 0.76 vs. 0.50 ± 0.52, respectively). The FISH technique revealed the presence of clastogenic and aneugenic effects in peripheral blood lymphocytes in both groups. The clastogenic effect was slightly more pronounced in the smelter workers; however, the difference was not statistically significant. The mean arsenic concentrations in urine (total arsenic species) and in toenail samples in the exposed group were 54.04 ± 42.26 μg/l and 7.63 ± 7.24 μg/g, respectively, being significantly different from control group 11.01 ± 10.84 μg/l and 0.51 ± 0.05 μg/g. No correlation between As content in urine or toenail samples and the genotoxic effect was found under study.

  • 6.
    Nilsson, Robert
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    The molecular basis for induction of human cancers by tobacco specific nitrosamines2011In: Regulatory toxicology and pharmacology, ISSN 0273-2300, E-ISSN 1096-0295, Vol. 60, no 2, p. 268-280Article in journal (Refereed)
    Abstract [en]

    Cellular DNA damage that is misrepaired or not repaired, constitutes a necessary, although not sufficient prerequisite for induction of cancer. For carcinogenic oral snuffs with extremely high concentrations of tobacco specific nitrosamines (TSNA) the DNA adduct levels predicted from animal experiments exceed those found in unexposed individuals. On the other hand, and supported by extensive Swedish epidemiological data, no significant increase of TSNA-induced DNA damages can be anticipated in humans from the use of low-nitrosamine oral snuffs. The extrapolated adduct concentrations are orders of magnitude lower than those found in the corresponding human tissues, a discrepancy that is difficult to account for by species differences. Furthermore, in exposed subjects the observed increment in the background levels of pyridyloxobutyl(POB)-hemoglobin adducts - a relevant indicator for TSNA activation - lie in a range predicted by rodent data. When based on the same type of tissues this provides justification for extrapolating rates of TSNA induced adduct formation from animals to humans. A TSNA exposure that does not affect the background level of pro-mutagenic DNA lesions should be considered as virtually safe. The high background concentrations of methylated and POB-DNA adducts in unexposed humans must be ascribed to other sources than tobacco.

  • 7.
    Tekle, Michael
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gromadzinska, Jolanta
    Joksic, Gordana
    Antic, Ruza
    Nilsson, Robert
    Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
    Dallner, Gustav
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Undén, Anna-Lena
    Brismar, Kerstin
    Plasma levels of insulin-like growth factor-I, insulin-like growth factor binding protein-1, coenzyme Q10 and vitamin E in female populations from Poland, Serbia and Sweden2010In: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 36, no 2, p. 188-194Article in journal (Refereed)
    Abstract [en]

    Exposure to environmental contaminants such as polycyclic aromatic hydrocarbons (PAHs), life style and nutritional status of a population are important factors that may influence normal serum levels of antioxidants and the insulin-like growth factor system. In this study we examined serum levels of insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-1 (IGFBP-1), coenzyme Q10 (CoQ) and vitamin E in healthy female populations (n = 4 x 100) aged 19-59 years from Poland (PL), Sweden (SE), Serbia I (SR I) and Serbia II (SR II). The last group lived in an environmental emergency area affected by the bombings of 1999 in Serbia. The Polish and SR I cohorts exhibited low IGFSD-score levels, (-2 to +/-0), compared to females from SE with IGFSD-score 0. In the SIR II population, the IGFSD range was between -1 and 1. The IGFBP-1 levels of the Polish and SIR I groups were lower than in the Swedish population, while the SR II levels showed a broader distribution, 20-80 mu g/l. The CoQ values in the Swedish and Polish samples were around 1 nmol/ml. In contrast. the SIR I cohorts exhibited higher concentrations, 1.5-3.5 nmol/ml and the SIR II group had extremely low levels, <0.5 nmol/ml. The vitamin E concentrations were similar in the Polish and Swedish populations, 20-40 nmol/ml, while it was twice as high, 40-80 nmol/ml in the SR I and very low in the SIR II group, which is half of the Polish and Swedish cohorts. These results suggest that different lifestyles and environmental factors affect both the IGF system and the antioxidants CoQ10 and vitamin E in female populations in Europe. The females living in the polluted area had different patterns of both the IGF and antioxidant systems. These findings may explain differences in morbidity and mortality in these countries.

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