Gassy degeneration

Nitric oxide (NO) gas spurs on brain degeneration, according to a study on page 1163. Nathan and colleagues show that the NO-producing enzyme iNOS accelerates brain destruction and death in a mouse model of Alzheimer's disease.Alzheimer's disease is a lethal neurodegenerative disease that causes progressive memory loss and dementia. The disease is associated with a build-up in the brain of peptide fragments derived from a protein called β-amyloid precursor protein (APP). APP is a protein that normally gets cleaved in the brain, although the functions of APP and of its primary cleavage products are poorly understood.

Mutations in APP, or in the enzymes that chop it up, result in the overproduction of the disease-causing peptide (known as Aβ). Although it is not completely clear how Aβ contributes to disease, it has been...