I'm sure you recall the experiments demonstrating life extension in mice through boosting the level of catalase in the mitochondria. Here, The Scientist follows up with a few interesting notes in their Hot Paper series: "Replicating the findings has proven difficult. Rabinovitch says that changes in veterinary care have led to euthanasia of mice that develop dermatitis and other ailments at early ages. This practice has confounded the replication of past longevity observations. ... Richard Miller at the University of Michigan, Ann Arbor, offers his opinion: 'If [catalase-boosting mutations] do increase lifespan in mice, the effect may depend in complicated ways on a specific and not well-characterized set of background genes and environmental factors.' ... Rabinovitch says he's about two-thirds of the way through aging studies with two different mouse strains. New data, he says, clarify the protection against age-related cardiac changes and nonhematologic cancers, and they are working on new transgenic models." Stay tuned.