Mitochondrial density contributes to the immune response of macrophages to lipopolysaccharide via the MAPK pathway.

We investigated the role of mitochondrial reactive oxygen species (ROS) in the response of macrophages to lipopolysaccharide (LPS) using RAW 264.7 cells and their ρ(o) cells lacking mitochondria. Mitochondrial density, respiratory activity and related proteins in ρ(o) cells were significantly lower than those in RAW cells.

Dynamic aspects of ascorbic acid metabolism in the circulation: analysis by ascorbate oxidase with a prolonged in vivo half-life.

Because AA (L-ascorbic acid) scavenges various types of free radicals to form MDAA (monodehydroascorbic acid) and DAA (dehydroascorbic acid), its regeneration from the oxidized metabolites is critically important for humans and other animals that lack the ability to synthesize this antioxidant. To study the dynamic aspects of AA metabolism in the circulation, a long acting AOase (ascorbate oxidase) derivative was synthesized by covalently linking PEG [poly(ethylene glycol)] to the enzyme. Fairly low concentrations of the modified enzyme (PEG-AOase) rapidly decreased AA levels in isolated fresh plasma and blood samples with a concomitant increase in their levels of MDAA and DAA.