| 1. |
- Dahle, Dag Olav, et al.
(författare)
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Uric acid and clinical correlates of endothelial function in kidney transplant recipients
- 2014
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Ingår i: Clinical Transplantation. - : Wiley. - 0902-0063 .- 1399-0012. ; 28:10, s. 1167-1176
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Tidskriftsartikel (refereegranskat)abstract
- Uric acid is associated with increased mortality in kidney transplant recipients (KTRs), but it is uncertain if this involves endothelial dysfunction. We hypothesized, first, that there was an association between uric acid and endothelial function, and second, that there were associations between endothelial function and cardiac and mortality risk scores.METHODS: One hundred and fifty-two patients were examined 10 wk after kidney transplantation by two measures of endothelial function, the brachial artery flow-mediated dilatation (FMD) expressed as percent dilatation (FMD%), and fingertip peripheral arterial tone (PAT) expressed as log-reactive hyperemia index (LnRHI). Risk scores were calculated from a recently validated formula. Other clinical correlates of endothelial function were described in stepwise linear regression models.RESULTS: Uric acid was associated negatively with FMD% in an age- and gender-adjusted model, while not in the multivariable model. No association was shown between uric acid and LnRHI. FMD% was associated negatively with risk scores in both crude and age- and gender-adjusted models (p < 0.01). LnRHI was associated negatively with risk scores in the latter model only (p < 0.05).CONCLUSIONS: Uric acid was neither associated with FMD% nor LnRHI in KTRs. There were significant associations between endothelial function indices and cardiac and mortality risk scores.
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| 2. |
- Fotouhi, Asal, et al.
(författare)
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Reduction of 8-oxodGTP in the nucleotide pool by hMTH1 leads to reduction in mutations in the human lymphoblastoid cell line TK6 exposed to UVA
- 2011
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Ingår i: Mutation research. - : Elsevier BV. - 0027-5107 .- 1873-135X. ; 715:1-2, s. 13-18
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Tidskriftsartikel (refereegranskat)abstract
- UVA has been suggested to play an important role in UV-induced mutagenesis. The mechanisms by which UVA induces mutations are still a matter of debate. Our aim was to investigate the protective capacity of hMTH1, a nucleotide pool sanitization enzyme with 8-oxodGTPase activity. Human B lymphoblastoid cells were stably transfected with shRNA directed against hMTH1. Clonogenic survival, mutations, intracellular and extracellular levels of 8-oxodG (8-oxo-7, 8-dihydro-2'-deoxyguanosine) and dG in the nucleotide pool of UVA-irradiated transfected and non-transfected cells were investigated. Mutations were determined in the thymidine kinase locus. Intracellular 8-oxodG and dG were measured using a modified ELISA and HPLC, respectively, after extraction of the nucleotide pool and conversion of nucleotides to their corresponding nucleosides. 8-oxodG in the medium was measured using ELISA. UVA-induced mutations were significantly higher while the survival was slightly lower in transfected compared to non-transfected cells. The increased mutation rate in transfected cells at increased exposure correlated with enhanced levels of 8-oxodG in the nucleotide pool, and a somewhat reduced level of 8-oxodG in the medium. The results indicate that the nucleotide pool is a significant target for UVA-induced mutations and implicates that hMTH1 plays an important role in protecting cells from UVA-induced oxidative stress.
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| 3. |
- Gradecka-Meesters, Dobroslawa, et al.
(författare)
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Assessment of the protective effects of selected dietary anticarcinogens against DNA damage and cytogenetic effects induced by benzo[a]pyrene in C57BL/6J mice
- 2011
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Ingår i: Food and Chemical Toxicology. - : Elsevier BV. - 0278-6915 .- 1873-6351. ; 49:8, s. 1674-1683
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 4. |
- Harms-Ringdahl, Mats, et al.
(författare)
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Tomato juice intake suppressed serum concentration of 8-oxodG after extensive physical activity
- 2012
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Ingår i: Nutrition Journal. - : Springer Science and Business Media LLC. - 1475-2891. ; 11, s. 29-
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Tidskriftsartikel (refereegranskat)abstract
- Background: DNA is constantly exposed to reactive oxygen species (ROS), spontaneously arising during the normal oxygen metabolism. ROS may result in temporary as well as permanent modifications in various cellular components such as lipids, proteins and DNA, which may have deleterious consequences. Demonstrating that a dietary supplementation of antioxidants can reduce oxidative DNA damage may provide evidence for the value of such supplementation in prevention of cancer and age related diseases. Findings: The present study was conducted to address whether tomato juice protects against ROS induced by extensive physical exercise in untrained individuals. As a marker of oxidative stress, serum levels of 8-oxodG were monitored using a modified ELISA. An intervention was performed involving 15 untrained healthy subjects who performed a 20 min physical exercise at 80% of maximum pulse using an ergometer bicycle. Blood samples were taken before and one hour after the exercise. The procedure was repeated after 5 weeks with a daily intake of 150 ml tomato juice and followed by a 5 weeks wash-out period and another 5 weeks with a daily intake of tomato juice. The results indicated that a daily intake of tomato juice, equal to 15 mg lycopene per day, for 5 weeks significantly reduced the serum levels of 8-oxodG after an extensive physical exercise. Conclusion: These data strongly suggest that tomato juice has a potential antioxidant effect and may reduce the elevated level of ROS induced by oxidative stress.
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| 5. |
- Kotova, Natalia, 1975-
(författare)
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Biomarkers for DNA damage in human biomonitoring
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Genomic DNA in humans is constantly exposed to different kinds of damage. Therefore, it is desirable to implement methods for detecting and measuring of inflicted body burden. Human biomonitoring (HBM) can here be a useful tool as a link between environmental exposure and disease outcome. The present thesis aims to monitor DNA damage in humans by studies on: 1) urinary thymidine dimer (T=T) as a novel biomarker (BM) of human exposure to UV-light; 2) enumeration of variants in HPRT gene in human peripheral blood lymphocytes by developing a sensitive flow cytometric (FCM) analysis; 3) the impact of dietary habits on genomic stability in vegetarians and omnivores in terms of micronuclei (MN) induction detected by FCM. Urinary T=T was quantified by a 32P-postlabeling technique, the kinetics of T=T excretion was studied and the method was validated by delivering controlled UV-doses. The major conclusion was that the amount of urinary T=T was determined by the UV dose, and hence T=T can be used as a BM of UV exposure. Moreover, a new approach for rapid and sensitive enumeration of HPRT-variants by FCM was developed. The obtained HPRT-frequencies were comparable to those previously published by others. Finally, the FCM assay for MN enumeration was applied to study effects of dietary habits in vegetarians and omnivores. The main finding was that vegetarians had significantly lower MN frequencies compared to omnivores. In summary, the applied BMs and respective methods have high sensitivity and/or throughput possibility which are important factors considered in HBM.
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| 6. |
- Kotova, Natalia, et al.
(författare)
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Genotoxicity of alcohol is linked to DNA replication-associated damage and homologous recombination repair
- 2013
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Ingår i: Carcinogenesis. - : Oxford University Press (OUP). - 0143-3334 .- 1460-2180. ; 34:2, s. 325-330
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Tidskriftsartikel (refereegranskat)abstract
- Although alcohol consumption is related to increased cancer risk, its molecular mechanism remains unclear. Here, we demonstrate that an intake of 10% alcohol for 4 weeks in rats is genotoxic due to induction of micronuclei. Acetaldehyde (AA), the first product of ethanol metabolism, is believed to be responsible for DNA damage induced by alcohol. Here, we observe that AA effectively blocks DNA replication elongation in mammalian cells, resulting in DNA double-strand breaks associated with replication. AA-induced DNA damage sites colocalize with the homologous recombination (HR) repair protein RAD51. HR measured in the hypoxhantineguaninefosforibosyltransferase (HPRT) gene is effectively induced by AA and recombination defective mammalian cells are hypersensitive to AA, clearly demonstrating that HR is essential in the repair of AA-induced DNA damage. Altogether, our data indicate that alcohol genotoxicity related to AA produces replication lesions on DNA triggering HR repair.
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| 7. |
- Lagerqvist, Anne, et al.
(författare)
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DNA repair and replication influence the number of mutations per adduct of polycyclic aromatic hydrocarbons in mammalian cells
- 2011
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Ingår i: DNA Repair. - : Elsevier BV. - 1568-7864 .- 1568-7856. ; 10:8, s. 877-886
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Tidskriftsartikel (refereegranskat)abstract
- Polycyclic aromatic hydrocarbons (PAH) are an important class of environmental contaminants many of which require metabolic activation to DNA-reactive bay or fjord region diolepoxides (DE) in order to exert their mutagenic and carcinogenic effects. In this study, the mutagenicity of the bay region diolepoxides (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) and ()-anti-1,2-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydrodibenzo[a,h]anthracene (DBADE) and the fjord region diolepoxides ()-anti-11,12-dihydroxy-13,14-epoxy-11,12,13,14-tetrahydrodibenzo[a,l]-pyrene (DBPDE) and (+/-)-anti-3,4-dihydroxy-1,2-epoxy-1,2,3,4-tetrahydrobenzo[c]-phenanthrene (BPhDE) was compared in nucleotide excision repair (NER) proficient and deficient hamster cell lines. The (32)P-postlabelling assay was applied to analyze DNA adduct levels and the Hprt gene mutation assay for monitoring mutations. Previously, we found that the mutagenicity per adduct was four times higher for DBPDE compared to BPDE in NER proficient cells. In these same cells, the mutagenicity of DBADE and BPhDE adducts was now found to be significantly lower compared to that of BPDE. In NER deficient cells the highest mutagenicity per adduct was found for BPDE and there was a tenfold and fivefold difference when comparing the BPDE data with the DBADE and BPhDE data, respectively. In order to investigate to what extent the mutagenicity of the different adducts in NER proficient cells was influenced by repair or replication bypass, we measured the overall NER incision rate, the rate of adduct removal, the rate of replication bypass and the frequency of induced recombination in the Hprt gene. Since NER turned out to be an important pathway for the yield of mutations, we further analyzed the role of transcription coupled NER versus global genome NER. However, our data demonstrate that neither of these pathways seems to be the sole factor determining the mutation frequency of the four PAH-DE and that the differences in the repair efficiency of these compounds could not be related to the presence of a bay or fjord region in the parent PAH.
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| 8. |
- Lagerqvist, Anne, et al.
(författare)
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Structural requirements for mutation formation from polycyclic aromatic hydrocarbon dihydrodiol epoxides in their interaction with food chemopreventive compounds
- 2011
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Ingår i: Food and Chemical Toxicology. - : Elsevier BV. - 0278-6915 .- 1873-6351. ; 49:4, s. 879-886
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Tidskriftsartikel (refereegranskat)abstract
- Chinese hamster V79 cells were used to investigate the protective effect of four known antimutagens present in food, chlorophyllin (CHL), ellagic acid (EA), epigallocathechingallate (EGCG) and benzylisothiocyanate (BITC), against potent mutagenic polycyclic aromatic hydrocarbon dial epoxides (PAH-DE) derived from benzo[a]pyrene (BP), dibenzo[a,h]anthracene (DBA), dibenzo[a,l]pyrene (DBP), and benzo[c]phenanthrene (BPh) known to be deposited on crops from polluted ambient air or formed during food processing. As fjord-region PAH-DE are more toxic and mutagenic than bay-region PAH-DE, we adjusted the concentrations of PAH-DE to induce approximately the same levels of adducts. The studies were performed using an assay indicating toxicity in terms of reduced cell proliferation together with the V79 Hprt assay for monitoring mutant frequencies. CHL significantly increased the survival and showed a protective effect against the mutagenicity of all PAH-DE. A significant protective effect of EA was found towards the mutagenicity of BPDE, DBPDE and BPhDE and with EGCG for BPDE and BPhDE. BITC had a slight positive effect on the mutagenicity of DBADE and BPhDE. Taken together, a novel and unexpected finding was that the antimutagenic activity could differ as much as by a factor of 7 towards four carcinogenic PAH metabolites being relatively similar in structure and genotoxic activity.
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| 9. |
- Vare, Daniel, et al.
(författare)
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DNA interstrand crosslinks induce a potent replication block followed by formation and repair of double strand breaks in intact mammalian cells
- 2012
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Ingår i: DNA Repair. - : Elsevier BV. - 1568-7864 .- 1568-7856. ; 11:12, s. 976-985
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Tidskriftsartikel (refereegranskat)abstract
- DNA interstrand crosslinks (ICLs) are highly toxic lesions that covalently link both strands of DNA and distort the DNA helix. Crosslinking agents have been shown to stall DNA replication and failure to repair ICL lesions before encountered by replication forks may induce severe DNA damage. Most knowledge of the ICL repair process has been revealed from studies in bacteria and cell extracts. However, for mammalian cells the process of ICL repair is still unclear and conflicting data exist. In this study we have explored the fate of psoralen-induced ICLs during replication, by employing intact mammalian cells and novel techniques. By comparative studies distinguishing between effects by monoadducts versus ICLs, we have been able to link the block of replication to the ICLs induction. We found that the replication fork was equally blocked by ICLs in wild-type cells as in cells deficient in ERCC1/XPF and XRCC3. The formation of ICL induced double strand breaks (DSBs), detected by formation of 53PB1 foci, was equally induced in the three cell lines suggesting that these proteins are involved at a later step of the repair process. Furthermore, we found that forks blocked by ICLs were neither bypassed, restarted nor restored for several hours. We propose that this process is different from that taking place following monoadduct induction by UV-light treatment where replication bypass is taking place as an early step. Altogether our findings suggest that restoration of an ICL blocked replication fork, likely initiated by a DSB occurs relatively rapidly at a stalled fork, is followed by restoration, which seems to be a rather slow process in intact mammalian cells.
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| 10. |
- Vare, Daniel, 1982-
(författare)
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Interstrand Crosslinks - Induction and repair
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- DNA crosslinking agents exhibit a variety of DNA lesions, such as monoadducts, DNA-DNA interstrand or intrastrand crosslinks or DNA-protein crosslinks. Agents that produce interstrand crosslinks (ICLs) exist naturally and are widely used in chemotherapy. Therefore, it is important to understand how the lesions induced by these agents are repaired. In bacteria, the repair is mainly dependent on nucleotide excision repair (NER) together with homologous recombination (HR) or translesion synthesis (TLS). In human cells, it is not clear how these lesions are repaired, and it is believed to be a more complicated process in which NER does not play as important a role as in prokaryotes. Here, we investigated the repair mechanisms mainly after treatment with psoralen but also with acetaldehyde, cisplatin and mitomycin C in some studies. As expected from studies on plasmids and in bacteria, we used new techniques to confirm that various ICL-inducing agents block replication fork elongation in mammalian cells. We also found that the replication fork was unable to bypass these lesions. We confirmed that ERCC1/XPF and the HR proteins BRCA2 and XRCC2/3 are vital for protection against ICL treatments. These proteins were also found to be equally important for the repair of monoadducts. To better understand ICL repair in mammalian cells, we developed a method to study the induction and unhooking of ICL in human fibroblasts. We found that ICLs were repaired and that 50% of the induced ICLs were unhooked within 3 hours following exposure. Additionally, we determined that XPA, but not XPE, is involved in ICL unhooking, although not affecting lethality. A step in ICL repair is the formation of double-strand breaks (DSBs), and we identified a replication-dependent formation of DSBs following ICL treatment. Furthermore, ERCC1/XPF was not necessary for DSB formation. The repair of these DSBs was performed by HR and involved ERCC1/XPF. Additionally, we were able to quantify the ICL unhooking in human fibroblasts and found that they can unhook ~2500 ICL/h. We also determined that a dose of approximately 400 ICL/cell is lethal to 50% of the cells, indicating that ICL unhooking is not the most critical step during the repair process.
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| 11. |
- Vare, Daniel, et al.
(författare)
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Quantification and repair of psoralen-induced interstrand crosslinks in human cells
- 2014
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Ingår i: Toxicology Letters. - : Elsevier BV. - 0378-4274 .- 1879-3169. ; 226:3, s. 343-350
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Tidskriftsartikel (refereegranskat)abstract
- Bi-functional alkylating agents that cause crosslinks are commonly used in chemotherapy. However, there is no conclusive knowledge for human cells regarding the number of induced interstrand crosslinks (ICLs) and the unhooking rate when the lesion is removed from one of the DNA strand. Using a newly developed method, we quantified the number of induced ICLs for the five furocoumarins; psoralen, 5-methoxypsoralen, 8-methoxypsoralen, tri-methoxypsoralen and angelicin. In quantitative terms, the results were in agreement with the values found by others. In kinetic studies using mammalian cells, we found that half of the psoralen-induced ICLs were unhooked within 2.5 h. The rate in normal human diploid fibroblasts was found to be 20,000 ICLs/h/cell. In comparison to survival, 2500 ICLs per cell led to 50% toxicity, indicating that the unhooking of the ICLs is not the crucial step for ICL tolerance. Surprisingly, only 3500 ICLs per cell corresponded to a significant delay in the replication fork elongation. The results indicate involvements of additional pathway(s) for the delay since the effect on replication elongation could be monitored when only 10% of the replication forks encounter an ICL.
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