Inclusion Criteria:  Men and women patients between 18 and 55 years of age Willing to provide saliva samples and have venous catheter installed for blood collection during the hospital visit Willing to provide informed consent and capacity to consent Use of effective method of birth control for women of childbearing capacity English Speaking  Exclusion Criteria:  Individuals with cognitive deficit incapable of providing informed consent will not be included Symptoms of flu or other seasonal infection four weeks preceding hospital visit Raynaud's syndrome (Raynaud phenomenon) Involvement in any therapeutic trials listed on clinicaltrials.gov, including exercise Metal inside or outside the body or claustrophobia prohibitive to MRI testing Diagnosed with mitochondrial disease m.3243A>G, or large scale mtDNA deletion (for healthy controls)