John Streicker was named chairman of Sentinel Real Estate Corp., New York, a new position at the real estate money manager.Mr. Streicker had been president; Millie Cassidy, who was a managing director, succeeded him. David Weiner was promoted to vice chairman, a new position, from managing director. The three form Sentinel's new executive committee. Also, Anita Breslin, Martin Cawley, Jacques Lewis, James Pope, Leland Roth, Gary Sheehan and George Tietjen were promoted to managing directors from senior vice presidents.