Search results for "DNA DAMAGE"

Oxidative stress and enzymatic antioxidant mechanisms in essential hypertension

2001

Age-related changes in antioxidant status and oxidative damage to lipids and dna in mitochondria of rat liver

2005

To investigate the correlation between oxidative stress and mitochondrial damage with aging, antioxidant system, levels of oxidative DNA damage and as an index of the loss of plasma membrane integrity lipid peroxidation and membrane potential were studied. Results showed that the activities of antioxidant enzymes superoxide dismutase (SOD) and catalase significantly decreased during aging, however glutathione peroxidase (GSH-PX) increased in the aged mitochondria and glutathione (GSH) did not change during aging. No statistical difference was observed in the lipid peroxidation of mitochondria between young and old animals. The level of oxidative DNA damage (measured as 8oxo-dG) tended to in…

[23] Ratio of reduced to oxidized glutathione as indicator of oxidative stress status and DNA damage

1999

Publisher Summary This chapter discusses the ratio of reduced to oxidized glutathione (GSH) as an indicator of oxidative stress status and DNA damage. Several methods have been proposed for the determination of GSH status in biological samples. Accurate determination of this status is largely dependent on the prevention of GSH autoxidation during sample processing. As the disulfide form (GSSG) is present only in minimal amounts with respect to the reduced form, a small GSH autoxidation during sample processing can give erroneously high GSSG level. The chapter describes high-performance liquid chromatography (HPLC) method for determining GSSG. It also presents a method for glutathione determ…

Role of Nitric Oxide for Modulation of Cancer Therapy Resistance

2010

Reactive nitrogen species (RNS) act as central second messengers in a balanced cellular network. While the complexity of nitric oxide (NO) signaling is far from being understood, and many controversial data can be found in the literature, there is evidence for NO as a major player of modulation of resistance to anticancer drugs and radiotherapy. Hypoxia in cancer tissues causes therapy resistance, and the hypoxia-inducing factor-1 (HIF-1) plays a predominant role in hypoxia-induced resistance. NO and NO-donating compounds sensitize tumor cells by inhibiting HIF-1 mediated transcription in hypoxic cells. Among a plethora of other genes, HIF-1-induced the transcription of the multidrug resist…

Characterization of hOGG1 Promoter Structure, Expression During Cell Cycle and Overexpression in Mammalian Cells

2001

Oxygen radicals are produced in all cells either by the normal cellular metabolism or by the exposure to external mutagens. The reactive oxygen species (ROS) generated can induce DNA damage. Among the principal lesions found in DNA due to ROS is an oxidized form of guanine, 8-oxo-7,8-dihydroguanine (8-oxoG). The biological relevance of this lesion has been unveiled by the study of Escherichia colt and Saccharomyces cerevisiae genes involved in the neutralization of the mutagenic effects of 8-oxoG (Cabrera et al., 1988; Nghiem et al., 1988; Radicella et al., 1988; van der Kemp et al., 1996). These genes fpg and mutY for E. colt and OGG1 for yeast, code for DNA glycosylases. Inactivation of a…

[39] DNA damage induced by ultraviolet and visible light and its wavelength dependence

2000

Publisher Summary DNA damage induced by solar radiation in mammalian cells consists largely of two types of modification: pyrimidine dimers and oxidative modifications. Pyrimidine dimmers that can be subdivided into cyclobutane pyrimidine dimmers, (CPDs) and (6-4) photoproducts are the characteristic and most abundant modifications after direct excitation of DNA, although they can also be formed indirectly by energy transfer from other excited molecules such as carbonyl compounds. Oxidative DNA damage, which includes various pyrimidine and purine modifications, sites of base loss (AP sites), and strand breaks, is generated in only low yield after direct excitation of DNA (except at very sho…

Environmental noise aggravates oxidative DNA damage, granulocyte oxidative burst and nitrate resistance in Ogg1−/− mice

2020

Bisfenola A saturošo zobārstniecības kompozītu genotoksicitāte

2019

Daži zobārstniecībā izmantojamie sveķu kompozīti satur monomērus ar BPA kā bāzes elementu, kas izraisa dzīvo šūnu genotoksicitāti un spēj izraisīt dzīvo šūnu nāvi. Šie monomēri spēj noārdīties cilvēka siekalās esošo esterāžu iedarbībā, tādējādi izdalot toksiskos noārdīšanās produktus mutes dobumā. Izdalītie monomēri pat var iekļūt asinsritē, izejot cauri zoba struktūrām uz pulpu. Šī pētījuma mērķis bija izpētīt zobārstniecības kompozīta materiālu ietekmi uz cilvēka asins šūnām, tieši uz limfocītiem, un novērtēt šūnu DNS bojājumu līmeni. Lai izpētītu šo jautājumu, 4 dažādi komerciāli pieejamie zobārstniecības kompozīta materiālu fragmenti tika izmērcēti izolētās cilvēka perifēro asiņu mononu…

WRN protects against topo I but not topo II inhibitors by preventing DNA break formation

2008

The Werner syndrome helicase/3′-exonuclease (WRN) is a major component of the DNA repair and replication machinery. To analyze whether WRN is involved in the repair of topoisomerase-induced DNA damage we utilized U2-OS cells, in which WRN is stably down-regulated (wrn-kd), and the corresponding wild-type cells (wrn-wt). We show that cells not expressing WRN are hypersensitive to the toxic effect of the topoisomerase I inhibitor topotecan, but not to the topoisomerase II inhibitor etoposide. This was shown by mass survival assays, colony formation and induction of apoptosis. Upon topotecan treatment WRN deficient cells showed enhanced DNA replication inhibition and S-phase arrest, whereas af…

Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies

2017

International audience; Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 μm thick polyester films and exposed to proton Bragg-peak energies (90–3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a ma…