Effect of mTOR Inhibition & Other Metabolism Modulating Interventions on the Elderly [SubStudy Rapa & cMRI to Evaluate Cardiac Function]

Inclusion Criteria: * men and women 70-95 years of age. * Subjects will be in good general health with all chronic diseases (hypertension, coronary artery disease, etc.) clinically stable. Selected subjects will be in good health (Per the World Health Organization good health will be defined as complete physical, mental, and social well-being and not merely the absence of disease or infirmity. * For our purposes all diseases or infirmities will be clinically stable whether managed by medications or not. * All ethnicities will be included. * For cardiac and brain imaging by MRI, a pre-MRI screening questionnaire will be used to assess MRI safety and neurological health. Exclusion Criteria: * Diabetes, (with A1c ≥6.5 or if treated with medication affecting glucose homeostasis History of skin ulcers or poor wound healing, * Smoking, * Liver disease, * Anti-coagulation, * Treatment with drugs known to affect cytochrome P450 3A (diltiazem, erythromycin, etc) due to its role in RAPA metabolism, * Treatment (\>30days of therapy or long term) with a systemic immunosuppressant (prednisone, etc.) within the last year, * History of recent (within 6 months) Myocardial Infarction or active Coronary Disease, * Patients with history of recent (within 6 months) intestinal disorders, * Exclusion criteria for MRI scan: known claustrophobia, metal implants in soft tissue of the body including pacemakers, aneurysm clips, ferrous metal fragments not anchored to bone (bullets, BBs, shrapnel, metal shavings), implanted medication pumps, and oral-facial metal appliances that are permanently secured but may result in low image quality. Participants may also be excluded for history of severe head trauma, brain injury, brain surgery, inflammation of the brain, or history of seizures. * Positive COVID19 test.