This image from the host broadcaster pool video shows U.S. President Barack Obama and Cuban President Raul Castro exchange handshakes on Friday April 10, 2015, at the opening of the Summit of the Americas in Panama. (AP Photo/Host Broadcaster Pool Video via AP Video)PANAMA CITY (AP) — Generations of isolation between the U.S. and Cuba were poised to fade away Saturday as their presidents prepare to sit down together for the first time since the height of the Cold War.