[1] UNIV COLORADO, MED CTR, DEPT PHARMACOL & PSYCHIAT, DENVER, CO 80202 USA
[2] UNIV MIAMI, SCH MED, DEPT NEUROL SURG, RES LABS, MIAMI, FL 33152 USA
[3] UNIV LINKOPING, DEPT CELL BIOL, LINKOPING, SWEDEN
[4] KAROLINSKA INST, DEPT GERIATR MED, S-10401 STOCKHOLM 60, SWEDEN