Oxidative damage to DNA yields guanine radical cations. Their gas-phase IR spectroscopic signature and acidity have been modelled by the radical cation of 9-methylguanine. Comparisons with quantum chemistry calculations suggest that radical cation formation produces the ground-state keto tautomer, which has an N-H acidity enhanced by ~470 kJ mol(-1).

Submit Manuscript | http://medcraveonline.com Abbreviations: TCR: γδT Receptor; RE: Rasmussen’s Encephalitis; CD: Cortical Dysplasia; APCs: Antigen Presenting Cells; MS: Multiple Sclerosis; BBB: Blood Brian Barrier; GBM: Glioblastoma Multiforme; MGMT: Methylguanine Methyltransferase; NK: Natural Killer; WNV: West Nile virus RR: Relapsing Remitting; PP: Primary Progressive; SP: Secondary Progres...

Azoxymethane (AOM) causes O(6)-methylguanine adduct formation which leads to G-->A transitions. Their repair is carried out by O(6)-methylguanine-DNA methyltransferase (MGMT). To evaluate the importance of this repair event in AOM-induced carcinogenesis, we examined the effect of O(6)-benzylguanine (BG), a potent inhibitor of MGMT, on colonic tumor development. Rats were treated weekly for 2 we...

BACKGROUND AND PURPOSE Patients with recurrent glioblastoma often exhibit regions of diffusion restriction following the initiation of bevacizumab therapy. Studies suggest that these regions represent either diffusion-restricted necrosis or hypercellular tumor. This study explored postmortem brain specimens and a population analysis of overall survival to determine the identity and implications...

This investigation was designed to explore transfer ANA (tANA) methyltransferase activity, urinary excretion levels of tRNA degradation products, and tRNA base composition in normal monkeys and in those with hepatocellular carcino mas induced by N-nitrosodiethylamine. After the develop ment of the tumor, 24-hr urine specimens were collected, the monkeys were sacrificed, and the livers were remo...

Drug resistance in myeloid leukemias may be mediated by an increased capacity to repair chemotherapy-induced DNA damage. Some tumor cell lines that are resistant to nitrosoureas contain the DNA repair protein O6-alkylguanine-DNA alkyltransferase (alkyltransferase). This protects cells by removing cytotoxic, nitrosourea-induced O6-alkylguanine adducts. We measured the level of alkyltransferase a...

The preponderance of G:C to A:T transitions in inherited and somatic human mutations has led to the hypothesis that some of these mutations arise as a result of formation of O(6)-methylguanine in DNA. To test this hypothesis, the fine structure map of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced mutations was determined in human lymphoblastoid cells in the human hypoxanthine-guanine-phos...