Expression of superoxide dismutase and catalase in rat brain as a function of age

Active oxygen species have been proposed to be involved in the aging process of the brain, therefore alterations of the levels of enzymes involved in the defence system against free radicals and other active species could substantially influence the aging process. In this study the enzyme activities of superoxide dismutase (Cu/Zn) and catalase as well as the relative levels of their mRNA were measured in the brain of Fischer F344 rats of various ages (5-37 months old). A gradual decrease in the activity of these enzymes (21-27%) was observed with increasing age. The alterations were paralleled by a decrease (39-40%) in the relative levels of these mRNA species. Thus the decrease in the activity of superoxide dismutase and catalase appears to be due to an age-dependent change in the expression of these genes.     

Stainable hepatic iron in 341 African American adults at coroner/medical examiner autopsy

Background  

Results of previous autopsy studies indicate that increased hepatic iron stores or hepatic iron overload is common in African Americans dying in hospitals, but there are no reports of hepatic iron content in other cohorts of African Americans.     

Age-dependent DNA methylation changes in the ITGAL (CD11a) promoter

DNA methylation patterns change with age in a complex fashion, typically with an overall decrease in genomic deoxymethylcytosine (d(m)C) content, but with local increases in some promoters that contain GC-rich sequences known as CpG islands. While the consequences of age-dependent CpG island methylation have recently been studied in organs such as the colon, less is known about the functional significance of the progressive hypomethylation of promoters lacking CpG islands, and the significance of age-dependent changes in T cell DNA methylation is completely unexplored. We asked if age-dependent DNA hypomethylation might contribute to overexpression of the T cell ITGAL gene, which encodes CD11a, a subunit of LFA-1. CD11a mRNA increased with age as well as with experimentally induced DNA hypomethylation. This increase correlated with hypomethylation of sequences flanking the ITGAL promoter in vitro and in aging. 'Patch' methylation of the region suppressed promoter function. DNA methyltransferases 1 and 3a also decreased with aging. These results indicate that hypomethylation of regions flanking the ITGAL promoter may increase CD11a expression, and suggest that age-dependent hypomethylation of promoters lacking CpG islands, perhaps due to decreased DNA methyltransferase expression, may be one mechanism contributing to increased T cell gene expression with aging.