Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

kurt julius isselbacher (september 12, 1925 july 18, 2019) was a german-born american physician and gastroenterologist.
kurt julius isselbacher

the nissan maxima is an automobile produced by nissan motor company in seven generations since 1981.
nissan maxima

defibrillation is the act of defibrillating the heart to treat the heart when it is not pushing blood because the heart muscle is not working in any pattern.
defibrillation