Catherine M Gedik

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Oxidized bases in DNA can be measured directly by high-performance liquid chromatography (HPLC). 7,8-Dihydro-8-oxo-guanine (8-OHgua), as the most abundant oxidation product, is often regarded as an indicator of oxidative stress. Estimates of endogenous 8-OHgua levels in human lymphocyte DNA are between 2 and 8 for every 10(5) unaltered bases--a high(More)
Accurate measurement of low levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in DNA is hampered by the ease with which guanine is oxidized during preparation of DNA for analysis. ESCODD, a consortium of mainly European laboratories, has attempted to minimize this artifact and to provide standard, reliable protocols for sample preparation and(More)
DNA breaks in eukaryotic cells can be detected by alkaline electrophoresis of cells embedded in agarose. DNA containing breaks extends in the direction of the anode forming an image resembling the tail of a comet. We have adapted this procedure of single cell gel electrophoresis (SCGE) for studying DNA damage and repair induced by UV-C-radiation, using HeLa(More)
BACKGROUND Experimentally imposed dietary restriction is known to extend the lifespan of rodents, perhaps by slowing the accumulation of oxidative damage that is thought to be one of the causes of aging. AIM OF THE STUDY We examined the effects of restricted total food intake, and protein and calorie restriction, on DNA oxidation and related biomarkers in(More)
Oxidative DNA damage is widely believed to play a role in cancer aetiology. It is therefore important to be able to assess it, both as an index of cancer risk, and in experiments to test agents with a potential to reduce oxidative damage, such as dietary antioxidants. However, there is an alarming discordance in estimates of concentrations of oxidative(More)
The 'antioxidant hypothesis' proposes that vitamin C, vitamin E, carotenoids, and other antioxidants occurring in fruit and vegetables afford protection against heart disease and cancer by preventing oxidative damage to lipids and to DNA, respectively. To test elements of this hypothesis, we have measured blood levels of dietary antioxidants, and(More)
A human cell extract is capable of carrying out damage-specific incision on supercoiled nucleoid DNA. The DNA breaks are detected by single cell gel electrophoresis. Incubation of the incised DNA with extract and DNA precursors results in resealing of the breaks, with retention of the supercoiled state of the DNA.
Calf thymus DNA containing defined levels of 8-hydroxy-2'-deoxyguanosine (8-oxodG) was prepared by treatment with visible light in the presence of photosensitiser Ro 19-8022. The DNA was checked for stability; after freeze-drying, the amount of 8-oxodG did not increase during 6 weeks' storage at room temperature. However, freeze-drying itself can introduce(More)
Fostriecin causes a delayed inhibition of replicative DNA synthesis in human cells, consistent with a role for DNA topoisomerase II (its target enzyme) at a late stage in replication. Fostriecin does not inhibit UV-induced excision repair. The less specific inhibitor novobiocin blocks repair in permeabilised cells given a low dose of UV, presumably through(More)
Mammalian cells permeabilised by treatment with saponin are capable of UV excision repair. We have developed an assay system which permits measurement of the later stages of repair, i.e. repair synthesis and ligation. Incomplete repair sites are accumulated in UV-irradiated cells by incubating them with DNA synthesis inhibitors hydroxyurea and aphidicolin.(More)