Aminopeptidase and cathepsin A activity in vitreous humor in relation to causes of death.

Brain autolysis happens rapidly, especially when environmental temperatures are high, and poses serious limitations for evaluating damage using morphologic methods. In the present study we have measured total proteins, cathepsin A and aminopeptidase activity in the vitreous humor in relation to cause of death and survival time. We have studied vitreous humor samples from 106 cadavers autopsied in the I.A.F. of Granada. The samples were classified according to causes of death as follows: myocardial infarction; hanging; other mechanical asphyxias; multiple trauma; craniocerebral trauma; other violent death; pulmonary functions; and other natural deaths. Total protein was measured by Lowry's method, and cathepsin A and aminopeptidase activity by the Bowen and Davison (1973) and Greenberg (1962) methods, respectively. Results are expressed in IU/l and in mIU/mg of protein. We found higher values of aminopeptidase and cathepsin A activity in groups with severe brain damage (craniocerebral trauma, multiple trauma, etc.) and lower values in groups of natural deaths. We believe, therefore, that aminopeptidase activity in vitreous humor may be a useful parameter for evaluating brain damage.