HIV infected subjects receiving antiretroviral treatment (lopinavir/ritonavir, stavudine, and lamivudine) for greater than 6 years through the Abbott M97-720 protocol with be evaluated for clinical lipoatrophy and mitochondrial function prior to switching nucleoside analogues from stavudine (d4T) to tenofovir and after 48 weeks or tenofovir treatment.~Subjects with or without lipoatrophy are eligible for the study. Adipose tissue biopsies to measure mitochondrial function, metabolic laboratory tests, and DAXA scans and clinical evaluations of lipodystrophy will be performed at Entry and after 48 weeks of tenofovir treatment.
HIV infected subjects receiving antiretroviral treatment for greater than 6 years with be evaluated for clinical lipoatrophy and mitochondrial function after switching nucleoside analogues from stavudine (d4T) to tenofovir treatment and after 4.~Hypothesis: Tenofovir therapy will increase peripheral fat content as assessed by DEXA and mitochondrial function at 48 weeks.