AIDS Dementia Complex/virology; Cytomegalovirus/isolation & purification; DNA, Viral/cerebrospinal fluid; JC Virus/isolation & purification; Polymerase Chain Reaction/methods; AIDS Dementia Complex/diagnosis; AIDS Dementia Complex/drug therapy; AIDS Dementia Complex/pathology; AIDS-Related Opportunistic Infections/drug therapy; AIDS-Related Opportunistic Infections/virology; Adolescent; Adult; Anti-HIV Agents/therapeutic use; Brain/pathology; Cytomegalovirus Infections/diagnosis; Cytomegalovirus Infections/drug therapy; Cytomegalovirus Infections/virology; Drug Therapy, Combination; Female; Foscarnet/therapeutic use; HIV-1/isolation & purification; Humans; Leukoencephalopathy, Progressive Multifocal/diagnosis; Leukoencephalopathy, Progressive Multifocal/drug therapy; Leukoencephalopathy, Progressive Multifocal/virology; Magnetic Resonance Imaging; Male; Middle Aged; Papillomavirus Infections/diagnosis; Papillomavirus Infections/drug therapy; Papillomavirus Infections/virology; RNA, Viral/cerebrospinal fluid; Zidovudine/therapeutic use