Healthy Clinical Trials

Background: When people have a stroke, they often have difficulty moving their arms and hands. Transcranial magnetic stimulation (TMS) can improve how well people with and without stroke can move their arms and hands. But the effects of TMS are minor, and it doesn t work for everyone. Researchers want to study how to time brain stimulation so that the effects are more consistent. Objective: To understand how the brain responds to transcranial magnetic stimulation so that treatments for people with stroke can be improved. Eligibility: Adults ages 18 and older who had a stroke at least 6 months ago Healthy volunteers ages 50 and older Design: Participants will have up to 5 visits. At visit 1, participants will be screened with medical history and physical exam. Participants with stroke will also have TMS and surface electromyography (sEMG). For TMS, a brief electrical current will pass through a wire coil on the scalp. Participants may hear a click and feel a pull. Muscles may twitch. Participants may be asked to do simple movements during TMS. For sEMG, small electrodes will be attached to the skin and muscle activity will be recorded. At visit 2, participants will have magnetic resonance imaging (MRI). They will lie on a table that slides into a metal cylinder in a strong magnetic field. They will get earplugs for the loud noise. At visit 3, participants will have TMS, sEMG, and electroencephalography (EEG). For EEG, small electrodes on the scalp will record brainwaves. Participants will sit still, watch a movie, or do TMS. Participants may be asked to have 2 extra visits to redo procedures. Read Less

The purpose of this study is to investigate how gut hormones and brain areas respond differently to gastric distention, tasteless calories, or palatable food and how this alters appetite. Read Less

This research examines vaccination recommendation perceptions and behaviors of physicians and advanced practice providers. Read Less

The purpose of this study is to determine the effects of dietary salt restriction on central hemodynamics and vascular function in men and women with salt resistant blood pressure. Read Less

The purpose of this study is to investigate the safe wearability and basic functions of the multi-modality sensors fabricated in the PI lab. Read Less

Most cardiometabolic diseases are characterized by increased muscle sympathetic nerve activity (MSNA) during rest and exercise which contributes to poor health outcomes. In healthy humans during muscle contraction, there is a blunting of skeletal muscle vascular responsiveness to increases in MSNA. However, the exact mechanisms involved are unknown although, best evidence suggests that the mechanism is endothelium derived, but nitric oxide (NO) and prostaglandin (PG) independent. Endothelium-derived hyperpolarizing factor (EDHF) is a NO and PG independent vasodilator in both cerebral and skeletal muscle circulations, however, it is unknown if EDHF contributes to vascular responsiveness during elevated MSNA. The application of lower body negative pressure (LBNP) is a safe and non-invasive manipulation that can be used to increase MSNA causing vasoconstriction in humans. Therefore, the purpose of this experiment is to determine if acute inhibition of EDHF alters central and peripheral vascular responses to LBNP at rest and during dynamic exercise. Thereby, providing evidence by which EDHF contributes to vascular control in healthy humans and identify it's potential as a therapeutic target for cardiometabolic diseases that are characterized by elevated MSNA Read Less

More than 250 million courses of antibiotics are prescribed annually in the ambulatory care setting in the United States alone, including more than 40 million in children under 18 years of age. The perception that antibiotic use has minimal attendant adverse side effects contributes to the over-utilization of antibiotics in clinical circumstances when they are not strictly indicated. We have learned much about the human microbiome. The emerging view is of profound life-long bi-directional interactions between our microbiota and our cells. Perturbations in the microbiota affect metabolic, immune, and cognitive physiology in experimental animal models. When a person takes an antibiotic, the antibiotic diffuses via the blood into all body compartments, selecting for resistance. We propose to examine the effects of two commonly used antibiotics (the beta-lactam, amoxicillin and the macrolide azithromycin) on human microbial populations and on metabolic and immune physiology, studying healthy human volunteers in a randomized controlled clinical trial at the NIH Clinical Center. Our hypothesis is that in addition to acutely perturbing the human microbiome, these agents will have measurable metabolic and immunologic effects, with residual effects in the weeks that follow. To test this hypothesis, we will assess the effects of a brief therapeutic course of antibiotics on microbiome and metagenome composition. After an initial evaluation period, antibiotics will be given for 7 days or 5 days (depending on the antibiotic), and there will be a post-treatment evaluation. A control group will receive no drug intervention. Specimens will be obtained from multiple sites at each of 10 time points occurring before, during, and after antibiotic administration, and used for estimating bacterial and fungal composition and gene content. We will also assess the effects of the antibiotic course on markers of innate and adaptive immunity as well as markers of metabolic and hormonal physiology. A subgroup of subjects will be studied in the clinical center metabolic chamber to assess 24-hour energy expenditure and its components (sleeping, diet-induced, and activity energy expenditure), as well as macronutrient oxidation rates (carbohydrate, fat, and protein), during 3 of the 10 study visits. In addition to the primary data analyses, we will build a model that integrates the temporal data to begin to understand the complex intertwined physiology between microbiome and host. Read Less

This is a single-center study at the Cleveland Clinic Main Campus designed to study biomarkers in healthy individuals to identify novel mechanisms of platelet activation and how platelets drive vascular inflammation and thrombosis in diseases. Read Less

The purpose of this investigation is to develop improved magnetic resonance imaging (MRI) techniques and hardware for studying brain function. MRI is a diagnostic tool that provides information about brain chemistry and physiology. This study will evaluate new MRI methods for monitoring blood flow to regions of the brain in response to simple tasks. The MRI machine used in this study is more powerful than those in most hospitals, permitting a higher visual resolution. Normal healthy volunteers over 18 years old may be eligible for this study. Candidates will be screened with a medical history and questionnaire, and a neurological examination. Study participants will have a yearly MRI scan. For this procedure, the subject lies on a stretcher that is moved into a donut-shaped machine with a strong magnetic field. A lightweight circular or rectangular coil a device that improves the quality of the images may be placed on the head. The scan time varies from 20 minutes to 3 hours; most scans last between 45 and 90 minutes. During the scan, the subject may perform simple tasks, such as listening to tapes, tapping a finger, moving a hand, watching a screen, or smelling a fragrance. More complex tasks may require thinking about tones or pictures and responding to them by pressing buttons. Information from this study will be used to develop better imaging methods that will, in turn, permit a greater understanding of normal and abnormal brain behaviors. ... Read Less

Background: - Imaging tests, such as magnetic resonance imaging (MRI), can provide information about heart and blood vessels. The tests let doctors can see the amount of blood vessel narrowing and vessel wall thickness. This information may help diagnose and treat heart disease and other conditions that lead to heart attacks. Better MRI methods are needed to improve heart disease diagnosis, especially by avoiding the use of radiation. Researchers are testing new techniques to improve the quality of heart MRI, compared with more complex studies like catheterization or angiography. Objectives: - To compare heart MRI techniques with other tests used to diagnose heart disease. Eligibility: - People at least 18 years of age who either have or may have heart disease, or are healthy volunteers. Design: Participants will be screened with a physical exam, medical history, and blood tests. They will have an angiography to study the inside of blood vessels. This test is an x-ray study of the blood vessels. It will be done either separately or as part of a set of tests to diagnose possible heart disease. Participants will have at least one and up to five MRI scans. The scans will involve different methods of studying the heart and blood vessels. Participants may also have a computed tomography scan to confirm the findings of an MRI scan. No treatment will be provided as part of this protocol. Read Less

The GLP-1 receptor (GLP1R) gene is found on the beta cells of the pancreas. Its role is in the control of blood sugar level by enhancing insulin secretion from the pancreas after eating a meal. The purpose of this research study to find out how genetic variations in GLP1R alter insulin secretion, in the fasting state and when blood sugars levels are elevated. Read Less

This study is a biomarker study designed to characterize how ketamine impacts the reward circuits of the human brain. Read Less