• NAD(P)H:quinone oxidoreductase expression in Cyp1a-knockout and CYP1A-humanized mouse lines and its effect on bioactivation of the carcinogen aristolochic acid I.

      Levova, Katerina; Moserova, Michaela; Nebert, Daniel W.; Phillips, David H.; Frei, Eva; Schmeiser, Heinz H.; Arlt, Volker M.; Stiborova, Marie (2012-12-15)
      Aristolochic acid causes a specific nephropathy (AAN), Balkan endemic nephropathy, and urothelial malignancies. Using Western blotting suitable to determine protein expression, we investigated in several transgenic mouse lines expression of NAD(P)H:quinone oxidoreductase (NQO1)-the most efficient cytosolic enzyme that reductively activates aristolochic acid I (AAI). The mouse tissues used were from previous studies [Arlt et al., Chem. Res. Toxicol. 24 (2011) 1710; Stiborova et al., Toxicol. Sci. 125 (2012) 345], in which the role of microsomal cytochrome P450 (CYP) enzymes in AAI metabolism in vivo had been determined. We found that NQO1 levels in liver, kidney and lung of Cyp1a1⁻/⁻, Cyp1a2⁻/⁻ and Cyp1a1/1a2⁻/⁻ knockout mouse lines, as well as in two CYP1A-humanized mouse lines harboring functional human CYP1A1 and CYP1A2 and lacking the mouse Cyp1a1/1a2 orthologs, differed from NQO1 levels in wild-type mice. NQO1 protein and enzymic activity were induced in hepatic and renal cytosolic fractions isolated from AAI-pretreated mice, compared with those in untreated mice. Furthermore, this increase in hepatic NQO1 enzyme activity was associated with bioactivation of AAI and elevated AAI-DNA adduct levels in ex vivo incubations of cytosolic fractions with DNA and AAI. In conclusion, AAI appears to increase its own metabolic activation by inducing NQO1, thereby enhancing its own genotoxic potential.
    • New aspects on mechanisms of chemical carcinogenesis: emphasis on species and gender/sex differences and developmental/aging determinants.

      Oesch, Franz; Dietrich, Cornelia; Naegeli, Hanspeter; Schwarz, Michael; van der Horst, Gijsbertus; Zanger, Ulrich; Oesch, Barbara; Weiss, Carsten (2008-11)
    • Nitrosamine and related food intake and gastric and oesophageal cancer risk: a systematic review of the epidemiological evidence.

      Jakszyn, Paula; Gonzalez, Carlos-Alberto (2006-07-21)
      AIM: To study the association between nitrite and nitrosamine intake and gastric cancer (GC), between meat and processed meat intake, GC and oesophageal cancer (OC), and between preserved fish, vegetable and smoked food intake and GC. METHODS: In this article we reviewed all the published cohort and case-control studies from 1985-2005, and analyzed the relationship between nitrosamine and nitrite intake and the most important related food intake (meat and processed meat, preserved vegetables and fish, smoked foods and beer drinking) and GC or OC risk. Sixty-one studies, 11 cohorts and 50 case-control studies were included. RESULTS: Evidence from case-control studies supported an association between nitrite and nitrosamine intake with GC but evidence was insufficient in relation to OC. A high proportion of case-control studies found a positive association with meat intake for both tumours (11 of 16 studies on GC and 11 of 18 studies on OC). A relatively large number of case-control studies showed quite consistent results supporting a positive association between processed meat intake and GC and OC risk (10 of 14 studies on GC and 8 of 9 studies on OC). Almost all the case-control studies found a positive and significant association between preserved fish, vegetable and smoked food intake and GC. The evidence regarding OC was more limited. Overall the evidence from cohort studies was insufficient or more inconsistent than that from case-control studies. CONCLUSION: The available evidence supports a positive association between nitrite and nitrosamine intake and GC, between meat and processed meat intake and GC and OC, and between preserved fish, vegetable and smoked food intake and GC, but is not conclusive.
    • NMR metabolomic analysis of fecal water from subjects on a vegetarian diet.

      Pettersson, Jenny; Karlsson, Pernilla Christina; Choi, Young Hae; Verpoorte, Robert; Rafter, Joseph James; Bohlin, Lars (2008-06)
      A vegetarian diet rich in phytochemicals may prevent colon carcinogenesis by affecting biochemical processes in the colonic mucosa. Compounds passing the digestive system reaching the colon could potentially be detected in fecal water. We previously reported that intact fecal water samples from human volunteers significantly decreased prostaglandin production and COX-2 protein expression in colonic cells. The aim with the present study was to further study the composition of the fecal waters, using NMR spectroscopy and multivariate data analysis, and to trace the COX-2 inhibiting activity. Intact fecal water samples and fractions thereof were analyzed for their ability to inhibit prostaglandin E2 production in the human colon cell line HT-29. The majority of the tested aqueous phases derived from intact fecal water showed ability to inhibit prostaglandin production in cells (13.8+/-1.34% inhibition, p=0.01). NMR analysis indicated the presence of significant quantities of amino acids and fatty acids. Major metabolites included; acetic acid, butanoic acid, propanoic acid, glutamic acid and alanine. Smaller amounts of glycine and fumaric acid, which are known to have anti-inflammatory and anti-tumorigenic properties, were also detected. This study describes for the first time NMR metabolomic analysis of fecal water from subjects on a vegetarian diet.
    • An oat bran meal influences blood insulin levels and related gene sets in peripheral blood mononuclear cells of healthy subjects.

      Ulmius, Matilda; Johansson-Persson, Anna; Krogh, Morten; Olsson, Peter; Onning, Gunilla (2011-11)
      The understanding of how fibre-rich meals regulate molecular events at a gene level is limited. This pilot study aimed to investigate changes in gene expression in peripheral blood mononuclear cells (PBMCs) from healthy subjects after consumption of an oat bran-rich meal. Fifteen subjects (8 men and 7 women, aged 20-28 years) ingested meals with oat bran or a control meal after an overnight fast. Blood samples for analysis of postprandial glucose, insulin and triglyceride concentrations were taken during 3 h, while PBMCs for microarray gene expression profiling from five men and five women were taken before and 2 h after the meal. Analysis of transcriptome data was performed with linear mixed models to determine differentially expressed genes in response either to meal intake or meal content, and enrichment analysis was used to identify functional gene sets responding to meal intake and specifically to oat bran intake. Meal intake as such affected gene expression for genes mainly involved in metabolic stress; indicating increased inflammation due to the switch from fasting to fed state. The oat bran meal affected gene sets associated with a lower insulin level, compared with the control meal. The gene sets included genes involved in insulin secretion and β-cell development, but also protein synthesis and genes related to cancer diseases. The oat bran meal also significantly lowered postprandial blood insulin IAUC compared to control. Further studies are needed to compare these acute effects with the long-term health effects of oat bran.
    • Occupational benzene exposure and the risk of lymphoma subtypes: a meta-analysis of cohort studies incorporating three study quality dimensions.

      Vlaanderen, Jelle; Lan, Qing; Kromhout, Hans; Rothman, Nathaniel; Vermeulen, Roel (2011-02)
      The use of occupational cohort studies to assess the association of benzene and lymphoma is complicated by problems with exposure misclassification, outcome classification, and low statistical power.
    • Occupational exposures contribute to educational inequalities in lung cancer incidence among men: Evidence from the EPIC prospective cohort study.

      Menvielle, Gwenn; Boshuizen, Hendriek; Kunst, Anton E.; Vineis, Paolo; Dalton, Susanne O.; Bergmann, Manuela M.; Hermann, Silke; Veglia, Fabrizio; Ferrari, Pietro; Overvad, Kim; et al. (2010-04-15)
      The aim of this study is to investigate to what extent occupational exposures may explain socioeconomic inequalities in lung cancer incidence after adjusting for smoking and dietary factors. Analyses were based on a subsample of the European Prospective Investigation into Cancer and Nutrition (EPIC study), a prospective cohort. The analyses included 703 incident lung cancer cases among men in Denmark, the United Kingdom, Germany, Italy, Spain and Greece. The socioeconomic position was measured using the highest level of education. The estimates of relative indices of inequality (RII) were computed with Cox regression models. We first adjusted for smoking (with detailed information on duration and quantity) and dietary factors (fruits and vegetables consumption) and then for occupational exposures. The exposure to three carcinogens [asbestos, heavy metals and polycyclic aromatic hydrocarbons (PAH)] was analyzed. The occupational exposures explained 14% of the socioeconomic inequalities remaining after adjustment for smoking and fruits and vegetables consumption. The inequalities remained nevertheless statistically significant. The RII decreased from 1.87 (95% CI: 1.36-2.56) to 1.75 (1.27-2.41). The decrease was more pronounced when adjusting for asbestos than for heavy metals or PAH. Analyses by birth cohort suggested an effect of occupational exposures among older men, while due to small number of endpoints, no conclusion could be drawn about the role of occupational exposures in educational inequalities among younger men. Our study revealed that the impact of occupational exposures on socioeconomic inequalities in cancer incidence, rarely studied until now, exists while of modest magnitude.
    • Occupational exposures, environmental tobacco smoke, and lung cancer.

      Veglia, Fabrizio; Vineis, Paolo; Overvad, Kim; Boeing, Heiner; Bergmann, Manuela; Trichopoulou, Antonia; Trichopoulos, Dimitrios; Palli, Domenico; Krogh, Vittorio; Tumino, Rosario; et al. (2007-11)
      BACKGROUND: There is uncertainty regarding the association of occupational exposures with lung cancer. We have studied the association between 52 high-risk job titles and lung cancer incidence in a large prospective study, with more than 200,000 participants followed for more than 6 years and 809 incident cases of lung cancer. METHODS: Hazard ratios and 95% confidence intervals were computed by the Cox proportional-hazard regression model, adjusting for country, age, sex, social class, diet, physical activity, and smoking habits. We used a CAREX-based job-exposure matrix to infer exposure to lung carcinogens. False-positive report probability was calculated as a measure of potentially false-positive results. RESULTS: Eighteen occupations, mainly related with agriculture, constructions, and metal processing, were associated with increased risk. In addition, incidence tended to increase with the number of hazardous jobs reported. When the occupations were classified according to the presumed exposure to specific carcinogenic agents, the hazard ratios were 1.5 (95% confidence interval = 1.2-1.9) for asbestos, 1.4 (1.1-1.8) for heavy metals, 1.4 (1.1-1.8) for polycyclic aromatic hydrocarbons, and 1.6 (1.2-2.1) for work-related environmental tobacco smoke. The estimated population attributable risk for employment in at least 1 at-risk job was 16% in men and 12% in women. CONCLUSIONS: This large prospective study suggests that exposure to occupational lung carcinogens is still a problem, with such exposures producing moderate to large increases in risk.
    • Occurrence of selenoprotein enzyme activities and mRNA in bovine mammary tissue.

      Bruzelius, K.; Hoac, T.; Sundler, R.; Onning, G.; Akesson, B. (2007-02)
      To elucidate the possible role of selenoproteins for milk formation and mammary gland physiology, the activities of selenoprotein enzymes and the expression of selenoprotein genes were studied in the bovine mammary gland. Messenger RNA was demonstrated for selenoprotein P, thioredoxin reductase 1, and for glutathione peroxidase (GPx) 1, 3, and 4. Significant differences in mRNA expression between the cows were seen for GPx 1 and GPx 3. The enzyme activity of glutathione peroxidase varied approximately 16-fold among cows, and the activity of thioredoxin reductase and the concentration of soluble Se varied approximately 6-fold among cows. There were positive correlations between glutathione peroxidase activity, thioredoxin reductase activity, and soluble Se, the correlation between glutathione peroxidase activity and soluble Se being the strongest. Furthermore, selenoprotein P expression correlated with GPx 1 mRNA expression and with soluble Se. There was also a correlation between glutathione peroxidase activity and the mRNA expression of GPx 1. The general conclusion from the data was that the activity of glutathione peroxidase and thioredoxin reductase and the mRNA expression of selenoprotein P and GPx 1 and 3 were influenced by Se status, but the expression of GPx 4 and thioredoxin reductase 1 were not. These results indicate that the Se status in mammary tissue is an important regulator of selenoprotein activity and expression, but that other factors are also in operation.
    • OGG1 expression and OGG1 Ser326Cys polymorphism and risk of lung cancer in a prospective study.

      Hatt, Lotte; Loft, Steffen; Risom, Lotte; Moller, Peter; Sorensen, Mette; Raaschou-Nielsen, Ole; Overvad, Kim; Tjonneland, Anne; Vogel, Ulla (2008-03-01)
      Oxidative DNA damage is believed to be implicated in lung carcinogenesis. 8-OxodG is a mutagenic and abundant oxidative modification induced in DNA. OGG1, NEIL1 and MUTYH are all involved in the repair and prevention of 8-oxodG-derived mutations and may be up-regulated by oxidative stress. The polymorphism OGG1 Ser326Cys has in some studies been associated with risk of lung cancer. In a population-based cohort of 57,053 Danes, we examined associations between mRNA levels of OGG1, NEIL1, MUTYH and NUDT in buffy coat material and subsequent lung cancer risk. 260 cases with lung cancer were identified and a sub-cohort of 263 individuals was matched on sex, age and smoking duration. We found that OGG1 mRNA levels in healthy individuals were not associated with risk of subsequent getting lung cancer. However, subjects with the OGG1 Cys326/Cys326 genotype had a higher expression level of OGG1 mRNA than wildtype-allele carriers. For homozygous Cys326 carriers, the incidence rate ratio (IRR) was 1.51 (95% CI: 1.09-2.08) for a doubling of the OGG1 mRNA level and there was a statistically significant interaction between the genotype and mRNA level. Among never-smokers, the IRR was 4.29 (1.09-16.9) per doubling of the OGG1 mRNA level, which was not found among smokers. Furthermore, we found a positive correlation between OGG1 mRNA expression and urinary excretion of 8-oxodG (RS=0.18; p<0.005). NUDT1 mRNA levels were omitted due to low and unreliable expression levels. The results suggest that OGG1 mRNA levels should be regarded as a biomarker of exposure to oxidative stress with induction of DNA rather than a marker of inborn DNA repair capacity.
    • On the origins and development of the (32)P-postlabelling assay for carcinogen-DNA adducts.

      Phillips, David H. (2012-11-23)
      The (32)P-postlabelling method for the analysis of carcinogen-DNA adducts originated 30years ago from Baylor College of Medicine in Houston and was the work of a team comprised of Kurt and Erica Randerath, Ramesh Gupta and Vijay Reddy. With subsequent modifications and developments, it has become a highly sensitive and versatile method for the detection of DNA adducts that has been applied in a wide range of human, animal and in vitro studies. These include monitoring human exposure to environmental and occupational carcinogens, investigating genotoxicity of chemicals, elucidating pathways of metabolic activation of carcinogens, mechanistic studies of DNA repair, analysing the genotoxicity of complex mixtures and in ecotoxicology studies. Its use has been instrumental in providing new clues to the aetiology of some cancers and in identifying a new human carcinogen.
    • Oxidative damage to DNA and antioxidant status in aging and age-related diseases.

      Olinski, Ryszard; Siomek, Agnieszka; Rozalski, Rafal; Gackowski, Daniel; Foksinski, Marek; Guz, Jolanta; Dziaman, Tomasz; Szpila, Anna; Tudek, Barbara (2007)
      Aging is a complex process involving morphologic and biochemical changes in single cells and in the whole organism. One of the most popular explanations of how aging occurs at the molecular level is the oxidative stress hypothesis. Oxidative stress leads in many cases to an age-dependent increase in the cellular level of oxidatively modified macromolecules including DNA, and it is this increase which has been linked to various pathological conditions, such as aging, carcinogenesis, neurodegenerative and cardiovascular diseases. It is, however, possible that a number of short-comings associated with gaps in our knowledge may be responsible for the failure to produce definite results when applied to understanding the role of DNA damage in aging and age-related diseases.
    • Oxidative damage to DNA and repair induced by Norwegian wood smoke particles in human A549 and THP-1 cell lines.

      Danielsen, Pernille Hogh; Loft, Steffen; Kocbach, Anette; Schwarze, Per E.; Moller, Peter (2009-03-31)
      Genotoxic effects of traffic-generated particulate matter (PM) are well described, whereas little data are available on PM from combustion of biomass and wood, which contributes substantially to air pollution world wide. The aim of this study was to compare the genotoxicity of wood smoke particulate matter (WSPM), authentic traffic-generated particles, mineral PM and standard reference material (SRM2975) of diesel exhaust particles in human A549 lung epithelial and THP-1 monocytic cell lines. DNA damage was measured as strand breaks (SB) and formamidopyrimidine DNA glycosylase (FPG) sites by the comet assay, whereas cell cytotoxicity was determined as lactate dehydrogenase release. The exposure to WSPM generated SB and FPG sites in both cell lines at concentrations from 2.5 or 25 microg/ml, which were not cytotoxic. Compared to all other studied particles, WSPM generated greater responses in terms of both SB and FPG sites. Organic extracts of WSPM and SRM2975 elicited higher levels of SB than native and washed PM at 25 and 100 microg/ml, whereas assay saturation precluded reliable assessment of FPG sites. During a 6h post-exposure period, in which the medium with PM had been replaced by fresh medium, 60% of the DNA lesions generated by WSPM were removed. In conclusion, WSPM generated more DNA damage than traffic-generated PM per unit mass in human cell lines, possibly due to the high level of polycyclic aromatic hydrocarbons in WSPM. This suggests that exposure to WSPM might be more hazardous than PM collected from vehicle exhaust with respect to development of lung cancer.
    • Oxidative stress and DNA damage caused by the urban air pollutant 3-NBA and its isomer 2-NBA in human lung cells analyzed with three independent methods.

      Nagy, Eszter; Johansson, Clara; Zeisig, Magnus; Moller, Lennart (2005-11-15)
      The air pollutant 3-nitrobenzanthrone (3-NBA), emitted in diesel exhaust, is a potent mutagen and genotoxin. 3-NBA can isomerise to 2-nitrobenzanthrone (2-NBA), which can become more than 70-fold higher in concentration in ambient air. In this study, three independent methods have been employed to evaluate the oxidative stress and genotoxicity of 2-NBA compared to 3-NBA in the human A549 lung cell line. HPLC-EC/UV was applied for measurements of oxidative damage in the form of 8-oxo-2'-deoxyguanosine (8-oxodG), (32)P-HPLC for measurements of lipophilic DNA-adducts, and the Comet assay to measure a variety of DNA lesions, including oxidative stress. No significant oxidative damage from either isomer was found regarding formation of 8-oxodG analysed using HPLC-EC/UV. However, the Comet assay (with FPG-treatment), which is more sensitive and detects more types of damages compared to HPLC-EC/UV, showed a significant effect from both 3-NBA and 2-NBA. (32)P-HPLC revealed a strong DNA-adduct formation from both 3-NBA and 2-NBA, and also a significant difference between both isomers compared to negative control. These results clearly show that 2-NBA has a genotoxic potential. Even if the DNA-adduct forming capacity and the amount of DNA lesions measured with the (32)P-HPLC and Comet assay is about one third of 3-NBA, the high abundance of 2-NBA in ambient air calls for further investigation and evaluation of its health hazard.
    • Oxidative stress and oxidative DNA damage is characteristic for mixed Alzheimer disease/vascular dementia.

      Gackowski, Daniel; Rozalski, Rafal; Siomek, Agnieszka; Dziaman, Tomasz; Nicpon, Krzysztof; Klimarczyk, Maciej; Araszkiewicz, Aleksander; Olinski, Ryszard (2008-03-15)
      Oxidative DNA damage may contribute to neuronal cell loss and may be involved in pathogenesis of some neurodegenerative diseases. We assessed the broad spectrum of oxidative DNA damage biomarkers and antioxidants in mixed Alzheimer disease/vascular dementia (MD) and in control patients. The amount of the products of oxidative DNA damage repair (8-oxo-2'-deoxyguanosine and 8-oxoguanine) excreted into urine and cerebrospinal fluid (CSF) was measured by gas chromatography/mass spectrometry with HPLC pre-purification. The level of 8-oxo-2'-deoxyguanosine in leukocytes' DNA, antioxidant vitamins and uric acid concentrations in blood plasma were analyzed by the mean of HPLC technique. For the first time we demonstrated oxidative DNA damage on the level of whole organism and in CSF of MD patients. Urinary excretion of oxidative DNA damage repair products were higher in patients with MD than in the control group. The level 8-oxoguanine in cerebrospinal fluid of MD patients almost doubled the level found in the control group. Also the concentrations of ascorbic acid and retinol in plasma were reduced in MD patients. Oxidative stress/DNA damage is an important factor that may be involved in pathogenesis of mixed dementia. It is likely that treatment of these patients with antioxidants may slow down the progression of the disease.
    • Oxidatively damaged DNA and inflammation in the liver of dyslipidemic ApoE-/- mice exposed to diesel exhaust particles.

      Folkmann, Janne Kjaersgaard; Risom, Lotte; Hansen, Christian Stevns; Loft, Steffen; Moller, Peter (2007-07-31)
      Epidemiological studies have shown that exposure to air pollution particles is associated with cardiovascular diseases, whereas the role in the initiation of atherosclerosis is unresolved. Atherosclerosis is considered to be an inflammatory disease that also involves oxidative stress. Here we investigated effects of oxidative stress elicited by diesel exhaust particles (DEP) in the aorta, liver, and lung of dyslipidemic ApoE(-/-) mice at the age when visual plaques appear in the aorta (11-13 weeks). DEP was administrated by intraperitoneal injection (0, 50, 500 and 5,000 microg DEP/kg bodyweight) in order to omit vascular effects secondary to pulmonary inflammation. The mice were killed either 6 or 24h after the administration. Inflammation was measured as the expression of inducible nitric oxide synthase (iNOS) and serum nitric oxide and DNA damage was measured by the comet assay. The expression of iNOS mRNA was increased in the liver 6h after the administration. The level of oxidized purine bases, determined as formamidopyrimidine DNA glycosylase sites was increased by 67% (95% CI: 11-124%) in the liver after 24h in the mice administrated with only 50 microg/kg bodyweight. However, there was no indication of systemic inflammation determined as the serum concentration of nitric oxide and iNOS expression, and DNA damage was not increased in the aorta. These observations indicate that intraperitoneal DEP injection does not induce inflammation or oxidatively damaged DNA in the lung and aorta, whereas a direct effect in terms of inflammation and oxidized DNA was observed in the liver of dyslipidemic ApoE(-/-) mice.
    • Oxidatively damaged DNA and its repair after experimental exposure to wood smoke in healthy humans.

      Danielsen, Pernille Hogh; Brauner, Elvira Vaclavik; Barregard, Lars; Sallsten, Gerd; Wallin, Maria; Olinski, Ryszard; Rozalski, Rafal; Moller, Peter; Loft, Steffen (2008-07-03)
      Particulate matter from wood smoke may cause health effects through generation of oxidative stress with resulting damage to DNA. We investigated oxidatively damaged DNA and related repair capacity in peripheral blood mononuclear cells (PBMC) and measured the urinary excretion of repair products after controlled short-term exposure of human volunteers to wood smoke. Thirteen healthy adults were exposed first to clean air and then to wood smoke in a chamber during 4h sessions, 1 week apart. Blood samples were taken 3h after exposure and on the following morning, and urine was collected after exposure, from bedtime until the next morning. We measured the levels of DNA strand breaks (SB), oxidized purines as formamidopyrimidine-DNA-glycosylase (FPG) sites and activity of oxoguanine glycosylase 1 (hOGG1) in PBMC by the comet assay, whereas mRNA levels of hOGG1, nucleoside diphosphate linked moiety X-type motif 1 (hNUDT1) and heme oxygenase 1 (hHO1) were determined by real-time RT-PCR. The excretion of 8-oxo-7,8-dihydro-oxoguanine (8-oxoGua) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in urine was measured by high performance liquid chromatography purification followed by gas chromatography with mass spectrometry. The morning following exposure to wood smoke the PBMC levels of SB were significantly decreased and the mRNA levels of hOGG1 significantly increased. FPG sites, hOGG1 activity, expression of hNUDT1 and hHO1, urinary excretion of 8-oxodG and 8-oxoGua did not change significantly. Our findings support that exposure to wood smoke causes systemic effects, although we could not demonstrate genotoxic effects, possibly explained by enhanced repair and timing of sampling.
    • Oxidatively damaged DNA in aging dyslipidemic ApoE-/- and wild-type mice.

      Folkmann, Janne Kjaersgaard; Loft, Steffen; Moller, Peter (2007-03)
      The free radical theory of aging depicts an accumulation of cellular oxidatively damaged DNA. In this study, we investigated this theory in mice with knocked-out apolipoprotein E gene (ApoE(-/-)), which develops atherosclerosis and wild-type counterparts. The level of oxidatively damaged DNA was investigated as strand breaks, endonuclease III- and formamidopyrimidine DNA glycosylase-sensitive sites by the comet assay. The level of DNA damage was mainly increased with age in the liver of ApoE(-/-) mice, whereas no increase was observed in the aorta or lung of the mice. This suggests that the accumulation of oxidized DNA in the liver of dyslipidemic ApoE(-/-) mice could be secondary to dysfunction of the lipid metabolism. Visually, the aortas of the ApoE(-/-) mice were clearly atherosclerotic as indicated by rigid texture and yellowish in color. However, the unaltered levels of oxidized DNA in severely atherosclerotic aortas of old ( approximately 70 weeks) ApoE(-/-) mice indicate that oxidative stress may not be a generalized phenomenon, but rather related locally to the individual plaques. In conclusion, the results of this study suggest that dyslipidemic ApoE(-/-) mice suffer from hepatic oxidative stress in terms of oxidized DNA, and this effect could be due to the dysfunction of lipid metabolism.
    • Oxidatively damaged DNA in rats exposed by oral gavage to C60 fullerenes and single-walled carbon nanotubes.

      Folkmann, Janne K.; Risom, Lotte; Jacobsen, Nicklas R.; Wallin, Hakan; Loft, Steffen; Moller, Peter (2009-05)
      BACKGROUND: C60 fullerenes and single-walled carbon nanotubes (SWCNT) are projected to be used in medicine and consumer products with potential human exposure. The hazardous effects of these particles are expected to involve oxidative stress with generation of oxidatively damaged DNA that might be the initiating event in the development of cancer. OBJECTIVE: In this study we investigated the effect of a single oral administration of C60 fullerenes and SWCNT. METHODS: We measured the level of oxidative damage to DNA as the premutagenic 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) in the colon mucosa, liver, and lung of rats after intragastric administration of pristine C60 fullerenes or SWCNT (0.064 or 0.64 mg/kg body weight) suspended in saline solution or corn oil. We investigated the regulation of DNA repair systems toward 8-oxodG in liver and lung tissue. RESULTS: Both doses of SWCNT increased the levels of 8-oxodG in liver and lung. Administration of C60 fullerenes increased the hepatic level of 8-oxodG, whereas only the high dose generated 8-oxodG in the lung. We detected no effects on 8-oxodG in colon mucosa. Suspension of particles in saline solution or corn oil yielded a similar extent of genotoxicity, whereas corn oil per se generated more genotoxicity than the particles. Although there was increased mRNA expression of 8-oxoguanine DNA glycosylase in the liver of C60 fullerene-treated rats, we found no significant increase in repair activity. CONCLUSIONS: Oral exposure to low doses of C60 fullerenes and SWCNT is associated with elevated levels of 8-oxodG in the liver and lung, which is likely to be caused by a direct genotoxic ability rather than an inhibition of the DNA repair system.