Age greater than or equal to 40 years for males and greater than or equal to 50 years for females.
Standard eligibility criteria for blood donation, per guidelines established by the Food and Drug Administration and the American Association of Blood Banks.
Ability to provide consent after full information is provided.
Pregnancy or lactation.
Patients with clinically significant dementia or psychiatric disturbances, including alcohol and substance abuse.
Presence of the following American Heart Association cardiovascular risks: diabetes mellitus, hypertension (systolic greater than 140 mmHg, diastolic greater than 90 mmHg), smoking (greater than 10 cigarettes/day), high density lipoprotein cholesterol less than 35 mg/dL, hyperlipidemia (total cholesterol greater than 240 mg/dL), family history of premature coronary heart disease.
Anticoagulant, thrombolytic, hemorrheologic and/or antiplatelet agents (within the last 10 days).
Any other condition or therapy which in the opinion of the investigators may pose a risk to the patient or confound the results of the study.