Volunteers with a history or evidence of present or past hypertension (BP greater than 140/90), diabetes mellitus, hypercholesterolemia (plasma cholesterol greater than 200 mg/dL), cardiac disease, peripheral vascular disease, coagulopathy, chronic smoking (2 pack-years or more), obesity (20% greater than ideal body weight), hyperhomocysteinemia (plasma homocysteine greater than 17 umol/1) or any other disease predisposing them to vasculitis will be excluded from the study.