This episode's headline: Aftershock; AIDS - ACT-UP; Gergen & Shields. The guests include KAMAL KHARRAZI, UN Ambassador, Iran; NELSON MANDELA; DAVID GERGEN, U.S. News & World Report; MARK SHIELDS, Washington Post; CORRESPONDENTS: SONIA RUSELO; JOHN ROSZAK. Byline: In New York: ROBERT MacNeil; In Washington: JAMES LEHRER