Comparison of antigen expression on normal urothelial cells in tissue section and tissue culture

Antigenic characterization of urothelial cells cultured from normal adult ureter was performed. These cells were cultured using a simplified isolation and culture technique and a commercially available serum-free medium. The cells growing in these cultures had epithelioid morphology and normal quantities of DNA. The antigen expression on these cultured normal urothelial cells was evaluated using a panel of monoclonal antibodies: 5G6.4, AN43, URO-5, anti-keratin and anti-blood group antibodies, and 425 (anti-epidermal growth factor receptor). Lower levels of anti-A and AN43 binding on cultured cells were observed than are seen on urothelial cells in sections of normal ureter, while the binding of anti-blood group H, 5G6.4, and URO-5 was unchanged. Binding of anti-epidermal growth factor receptor antibody 425 was improved if the cells were grown in medium lacking epidermal growth factor. These results confirm the urothelial origin of these cultured urothelial cells but indicate that some antigenic differences between cultured normal urothelial cells and urothelial cells in situ in the normal ureter exist.     

Aging,energy, and oxidative stress in neurodegenerative diseases

The etiology of neurodegenerative diseases remains enigmatic; however, evidence for defects in energy metabolism, excitotoxicity, and for oxidative damage is increasingly compelling. It is likely that there is a complex interplay between these mechanisms. A defect in energy metabolism may lead to neuronal depolarization, activation of N-methyl-D-aspartate excitatory amino acid-receptors, and increases in intracellular calcium, which are buffered by mitochondria. Mitochondria are the major intracellular source of free radicals, and increased mitochondrial calcium concentrations enhance free radical generation. Mitochondrial DNA is particularly susceptible to oxidative stress, and there is evidence of age-dependent damage and deterioration of respiratory enzyme activities with normal aging. This may contribute to the delayed onset and age dependence of neurodegenerative diseases. There is evidence for increased oxidative damage to macromolecules in amyotrophic lateral sclerosis, Huntington's disease, Parkinson's disease, and Alzheimer's disease. Potential therapeutic approaches include glutamate release inhibitors, excitatory amino acid antagonists, strategies to improve mitochondrial function, free radical scavengers, and trophic factors. All of these approaches appear promising in experimental studies and are now being applied to human studies.     

Ontogeny and thymus-dependence of T cell surface antigens in Xenopus : flow cytometric studies on monoclonal antibody-stained thymus and spleen

Recently generated anti-Xenopus T cell monoclonal antibodies (mAbs) to the 120 kDA XTLA-1 determinant and against the putative CD5 and CD8 homologues, together with anti-IgM and anti-MHC class II mAbs, are used in dual colour flow cytometric experiments to characterize cell surface antigenic expression on lymphocytes in thymus and spleen of Xenopus laevis during larval and early adult life and also in metamorphosis-inhibited animals. Histological confirmation of T cell emergence early in larval ontogeny is supplied by cryostat sections stained for CD8. Five-day thymectomy i.e. prior to T-lineage cell differentiation in the thymus, abolishes T cell marker expression in the spleen for up to 1 year. Moreover, late larval (20 days) or early adult (3 months) thymectomy (i.e. removal after peripheralization of T cells has occurred) also leads to severe depletion of mAb-defined T cells in the spleen.     

High aggregate burden of somatic mtDNA point mutations in aging and Alzheimer's disease brain.

The mitochondrial theory of aging proposes that mitochondrial DNA (mtDNA) accumulates mutations with age, and that these mutations contribute to physiological decline in aging and degenerative diseases. Although a great deal of indirect evidence supports this hypothesis, the aggregate burden of mtDNA mutations, particularly point mutations, has not been systematically quantified in aging or neurodegenerative disorders. Therefore, we directly assessed the aggregate burden of brain mtDNA point mutations in 17 subjects with Alzheimer's disease (AD), 10 elderly control subjects and 14 younger control subjects, using a PCR-cloning-sequencing strategy. We found that brain mtDNA from elderly subjects had a higher aggregate burden of mutations than brain mtDNA from younger subjects. The average aggregate mutational burden in elderly subjects was 2 x 10(-4) mutations/bp. The bulk of these mutations were individually rare point mutations, 60% of which changed an amino acid. Control experiments ensure that these results were not due to artifacts arising from PCR error, mistaken identification of nuclear pseudogenes or ex vivo oxidation. Cytochrome oxidase activity correlated negatively with increasing mutational burden. These findings significantly bolster the mitochondrial theory of aging.