chapter  8
20 Pages

Calpain and Caspase in Ischemic and Traumatic Brain Injury

Programmed cell death or apoptosis is cell death generally characterized by the presence of DNA fragmentation at the nucleasome linkage regions and DNA condensation, as well as cell shrinkage giving way to the formation of apoptotic bodies.1 Apoptosis occurs physiologically during development and other stages of its lifetime to eliminate unwanted cells. Unscheduled apoptosis also occurs in a large number of pathological or injurious conditions.2 Oncosis (or oncotic necrosis) occurs when cells have been acutely and severely injured to a point that is beyond repair.1 It is characterized by the presence of massive ion (Ca2+ and Na+) influx, mitochondria and cell swelling, massive multisite DNA breakage and plasma membrane bursting. Both forms of cell death have been well documented in acutely injured neurons. Necrosis is a term that means “deadness,” which occurs in the end-stage of both apoptosis and oncosis, thus is confusing and should be avoided.3