EurekAlert! notes a demonstration of a comparatively straightforward method of mitigating stroke damage: "In one study, rats' brains were subjected to ischemia - severely reduced blood flow - for two hours in a model of stroke. Researchers then administered nicotinamide adenine dinucleotide, or NAD+, immediately after "reperfusion," or resumption of blood flow. Reperfusion is the time when stroke damage actually occurs because brain cells are suddenly exposed to highly reactive and unstable oxygen molecules, which are toxic. The researchers found that NAD+ reduced brain cell death from reperfusion by 70 to 86 percent compared with rats not given the treatment ... NAD+ plays a number of essential roles in cell metabolism. One role is supporting the activity of the DNA repair enzyme PARP-1, which normally repairs cell damage from brain infection. In response to reperfusion following ischemia or brain trauma, PARP-1 is overactivated. As a result, it quickly depletes all available NAD+, in a sense its 'fuel,' and is unable to repair cell damage, leading to brain cell death."