Search results for "free radical damage"
showing 6 items of 6 documents
Intra- and extra-cellular DNA damage by harmine and 9-methyl-harmine
2014
It is known that b-carbolines are able to produce photosensitized damage in cell-free DNA, but there is little information on their effects on cellular DNA. Therefore, we have analyzed the DNA damage produced by harmine and 9-methyl-harmine under UVA irradiation in V79 cells, together with the associated generation of micronuclei and photocytotoxicity. The results indicate that the most frequent photoproducts generated in the cellular DNA are modified purines such as 8-oxo-7,8-dihydroguanine. Only relatively few single-strand breaks were observed. CPDs were absent, although they were generated in cell-free DNA irradiated under the same conditions. The overall extent of DNA damage in the cel…
Increased oxidative stress is responsible for ether-lipid loss in the retina of senescence accelerated mouse (SAM)
2006
International audience; Purpose: Ether–lipids represent an important class of retinal phospholipids but their exact functions are still unknown. They might act as antioxidants since the vinyl–ether double bond they contain could be the target for newly formed oxygenated radicals. In this work, we investigated the status of ether–lipids and aldehydes, their oxidative degradation products in the retina of a mouse model for aging, the senescence–accelerated mouse prone 8 (SAM P8), in which we reported a reduction of retinal function following 12 months of age (ARVO 2004 E–abstract 797). We completed this study by evaluating the oxidative stress in the retina. Methods: The quantification of eth…
Photolysis of N-hydroxpyridinethiones: a new source of hydroxyl radicals for the direct damage of cell-free and cellular DNA.
1996
N-Hydroxypyridine-2-thione (2-HPT), known to release hydroxyl radicals on irradiation with visible light, and two related compounds, viz. N-hydroxypyridine-4-thione (4-HPT) and N-hydroxyacridine-9-thione (HAT), were tested for their potency to induce DNA damage in L1210 mouse leukemia cells and in isolated DNA from bacteriophage PM2. DNA single-strand breaks and modifications sensitive to various repair endonucleases (Fpg protein, endonuclease III, exonuclease III, T4 endonuclease V) were quantified. Illumination of cell-free DNA in the presence of 2-HPT and 4-HPT gave rise to damage profiles characteristic for hydroxyl radicals, i.e. single-strand breaks and the various endonuclease-sensit…
Assessment of the toxicity of cholesterol oxides on retinal pigment epithelial cultured cells
2006
International audience; Purpose: Among the retinal lipid deposits found in AMD (age related macular degeneration), esterified and unesterified cholesterol have been identified. Cholesterol that accumulates in Bruch's membrane could be oxidized and lead to cholesterol oxides known as oxysterols. These compounds have cytotoxic activities on many vascular cell types, and we conducted this study to evaluate the cytotoxics effects of oxysterols on retinal pigment epithelial (RPE) cells. Methods: Human RPE cells (ARPE–19) were cultured and treated by 7–ketocholesterol (7–keto), 7–betahydroxycholesterol (7–beta) and 25–hydroxycholesterol (25–OH). ARPE–19 cells viability was determined with MTT ana…
[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…
Oxysterols Incorporate in Primary Porcine Retinal Pigment Epithelial Cells and Induce Inflammation and Oxidative Stress
2006
International audience; Purpose: : Aging is associated with an accumulation of cholesterol in the Bruch’s membrane. Cholesterol is prone to undergo oxidation and to generate oxysterols that have cytotoxic properties. The aim of this study was to evaluate the effects of oxysterols on cell viability, oxidative stress and inflammation and to measure oxysterol incorporation in primary porcine retinal pigment epithelial (RPE) cell cultures. Methods: : Porcine RPE cells were incubated with oxysterols (24S–hydroxycholesterol, 24OH ; 25–hydroxycholesterol, 25OH and 7–ketocholesterol, 7K) (100µg, 50µM) for 24 and 48h. Cell viability was evaluated by measuring mitochondrial succinate dehydrogenase (S…