Fat Metabolism in OSA and COPD

This research study involves 3 visits for subjects and healthy controls. The first visit is the screening visit and includes review of the informed consent and a DXA scan and the second and third visit for the study days. For the first test day, 3 hours of the subjects time will be for urine and blood sample collection, and to stable isotope administration (deuterated water, isotopically labeled amino acids). Subjects are allowed to go home after and eat normally. On the second study day, subjects will arrive early that morning. For the duration of the study, subjects have to lie in the bed (except for bathroom privileges). They can watch tv or bring and use a book/tablet. The research nurse or study staff will be present in the human subject area to assist the subject if necessary. Subjects are not allowed to eat or drink during the second test day, except for the test drink (meal) and water. One IV catheter will be placed in a vein of the arm/hand for blood draws. The hand will be placed in a hot box during blood collection. Another IV catheter will be placed in the contra-lateral forearm for a primed and continuous infusion of isotopes (isotopically labeled amino acids and glycerol). Each day, a total of 80-100 ml of blood will be obtained. Stable isotopes will be ingested and infused on the first test day and added to the test drinks and infused on the second day. On the second test day, subjects will fill out questionnaires. After completion of the study, we will provide the subject with a meal.