View clinical trials related to Physiology.
Filter by:This study will combine Duffin's rebreathing procedure with additional study procedures, such as quantitative pupillometry, that are planned for subsequent clinical studies in order to confirm feasibility and gather reproducibility data using the procedure. The reproducibility of Duffin rebreathing has been assessed previously by Mahamed and Duffin (2001) performing hyperoxic and hypoxic rebreathing procedures measured once daily for 14 consecutive days and then by Jensen et al. (2010) performing 4 pairs of hyperoxic and hypoxic rebreathing procedures in 1 day followed by 1 pair on 4 additional days separated by weeks to more than a month. The present study is an unblinded reproducibility assessment to assess variability of the ventilatory response to Duffin's rebreathing procedure. Subjects will report to the study site for screening between Days -28 to -2 and then will return to the site on Day -1 for baseline assessments and check-in. After check-in (Day -1), subjects will remain in study site for PD assessments on Day 1 and check out on Day 2. Paired rebreathing procedures (i.e., at two different isoxic end tidal PO2 [partial pressure oxygen] levels) will be performed on Day 1 at 0, 2, 4, and 6 hours. An additional pair of rebreathing procedures will be performed on Day 2 before checkout (approximately 24 hours). Subjects will not be administered any drugs in this study.
The investigators will seek to determine the relationship between heart rate and middle cerebral artery (MCA) cerebral blood flow (CBF), as well as better understand the hemodynamic determinants of MCA CBF velocity. In order to manipulate heart rate, the investigators will recruit patients already scheduled for clinically indicated elective electrophysiological studies, where temporary pacing catheters placed in the right atrium can be used to artificially pace the heart at controlled rates. MCA CBF will be measured by transcranial Doppler ultrasound.
Investigation of the importance of vagal signaling for the glucohomeostatic effects of GLP-1. The study will include physiological studies of truncally vagotomized participants and matched controls.
Renal parenchymal blood flow can be divided in cortical and medullary blood flow. Changes and factors affecting renal medullary blood flow have not been studied in detail previously as investigators/doctors did not have tools to monitor renal medullary blood flow in vivo. Since Trueta first described renal medullary blood flow, multiple attempts have been made to study renal medullary blood flow using invasive methods. Recently renal medullary blood flow measurement using contrast US has emerged as a promising technique that investigators can use to study renal medullary blood flow in vivo. In this study investigators are aiming to study changes in renal parenchymal (cortical and medullary) blood flow with exercise in healthy subject.
Few is known on meat protein digestibility in humans and the impact of cooking process, while excessive intake of processed meat has been suggested to increase the risk of colorectal cancer. This study aims to measure in vivo in humans the real digestibility of beef meat proteins depending 2 cooking processes, using ileal tubes and stable isotopes.