Pyrimidine base damage is increased in women with BRCA mutations.

Oxidatively-induced DNA damage was measured in the DNA of WBC from two groups of women: carriers of a BRCA mutation, but asymptomatic for disease, and healthy controls. Two oxidatively induced lesions were measured: a formamide remnant of pyrimidine base and the glycol modification of thymine. These lesions, employed previously in studies of the effects of smoking, antioxidant usage and ovarian cancer, are proving valuable indicators of oxidative stress.

Covalently linked tandem lesions in DNA.

Reactive oxygen species (ROS) generate a type of DNA damage called tandem lesions, two adjacent nucleotides both modified. A subcategory of tandem lesions consists of adjacent nucleotides linked by a covalent bond. Covalently linked tandem lesions generate highly characteristic liquid chromotography-tandem mass spectrometry (LC-MS/MS) elution profiles.

Profiling oxidative DNA damage: effects of antioxidants.

The goal of this research was to determine whether antioxidant usage could be correlated with changes in DNA damage levels. Liquid Chromatography-tandem Mass Spectrometry (LC-MS/MS) was used to simultaneously measure five different oxidatively-induced base modifications in the DNA of WBC. Measurements of the five modifications were made before and after an 8-week trial during which participants took the SU.

Reduction in oxidatively generated DNA damage following smoking cessation.

Background: Cigarette smoking is a known cause of cancer, and cancer may be in part due to effects of oxidative stress. However, whether smoking cessation reverses oxidatively induced DNA damage unclear. The current study sought to examine the extent to which three DNA lesions showed significant reductions after participants quit smoking.

The 1-carbamoyl-2-oxo-4,5-dihydroxyimidazolidine component of ROS-induced DNA damage in white blood cells.

The 1-carbamoyl-2-oxo-4,5-dihydroxyimidazolidine modification of cytosine is a known base modification produced in vitro by oxidative stress. However, the presence of this modification in vivo has not been established. In this study the introduction of this base modification into dinucleoside monophosphates was accomplished using the Fenton reaction.

Assessment of DNA damage at the dimer level: measurement of the formamide lesion.

UVC-radiation-induced DNA damage was measured in mouse fibroblast cells using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in conjunction with isotopically labeled internal standards. The thymine glycol and formamide lesions were assayed in the form of modified dinucleoside monophosphates. The 8-oxo-7,8-dihydroguanine lesion was measured as the modified nucleoside.

Singlet oxygen-induced DNA damage.

Singlet oxygen, hydrogen peroxide, hydroxyl radical and hydrogen peroxide are the reactive oxygen species (ROS) considered most responsible for producing oxidative stress in cells and organisms. Singlet oxygen interacts preferentially with guanine to produce 8-oxo-7,8-dihydroguanine and spiroiminodihydantoin. DNA damage due to the latter lesion has not been detected directly in the DNA of cells exposed to singlet oxygen.

A novel approach to DNA damage assessments: measurement of the thymine glycol lesion.

A different approach to the measurement of DNA damage has been developed based on the fact that many lesions can be excised from DNA in the form of modified dinucleoside monophosphates. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used in conjunction with isotopically labeled internal standards to quantify the lesion. The method has several advantages, including high sensitivity for the detection of dinucleoside monophosphates.

Measurement of DNA adducts in cells exposed to cisplatin.

The two main cisplatin-induced DNA lesions, G--G and A--G, have been measured in cells exposed to the drug. (G--G and A--G denote the intrastrand bifunctional adducts formed between adjacent purine bases.) It has proven feasible, using liquid chromatography-tandem mass spectrometry (LC-MS/MS), observe the G--G and A--G lesions in mouse fibroblast cells exposed for 1 h to a 120 microM concentration of cisplatin.

DNA damage measured by liquid chromatography-mass spectrometry in mouse fibroblast cells exposed to oxidative stress.

Oxidative DNA damage can result from environmental factors, such as radiation, as well as from the untoward consequences of normal metabolic processes. It is of interest to assay oxidative DNA damage in cells and tissues because this damage has been implicated in human disease, particularly cancer. Eleven indicators of oxidative DNA damage have been measured by Liquid Chromatography-Mass Spectrometry (LC-MS) in DNA extracted from cells exposed to oxidative stress.

Detection and characterization of formamido lesions in DNA by liquid chromatography-mass spectrometry.

DNA X-irradiated in oxygenated aqueous solution produces the formamido lesion from the breakdown of pyrimidine nucleosides. This pyrimidine breakdown product inhibits the hydrolysis by nuclease P1 of the phosphoester bond 3' to the damaged nucleoside. Consequently, the lesion can be obtained from an enzymatic digest of the DNA as a modified dinucleoside monophosphate in which the 5' nucleoside contains the lesion.