View clinical trials related to Healthy Volunteers.
Filter by:The objectives of this study are to investigate the effects of short-time high-intensity interval training on tissue glucose and fat metabolism in healthy lean subjects and type 2 diabetic patients using modern and noninvasive imaging methods positron emission tomography (PET), magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS).
Background: - Magnetic resonance imaging (MRI) is a widely used scanning technique to obtain images of the human body and evaluate activity in the brain. A particular MRI method called magnetic resonance spectroscopy (MRS) can be used to study brain chemistry as well, which may help researchers who are studying new treatments for psychiatric illnesses. Researchers are interested in improving current MRI and MRS techniques, as well as developing new MRI and MRS techniques to view and measure brain chemicals and brain activity. Objectives: - To implement, develop, and optimize brain chemistry imaging techniques using magnetic resonance imaging and magnetic resonance spectroscopy. Eligibility: - Healthy individuals between 18 and 65 years of age. Design: - This study will involve a screening visit and a scanning visit at the National Institutes of Health Clinical Center. - Participants will be screened with a full medical and physical examination, blood and urine tests, and neurological testing. - During the second visit, participants will have an MRI scan of the brain. (Participants who have received an MRI within the past year will not need to have a second one; the images of the previous scan will be used for this study.) All participants will then have an MRS scan using the same scanning equipment.
The influence of genes on addictive and neuropsychiatric disorders is complex, especially given that multiple genes likely influence certain behaviors that are correlated with addiction. Researchers are interested in looking at the genetic information of individuals who are enrolled on National Institute for Drug Abuse studies to investigate specific genetic variants that may be related to substance abuse. Researchers will study the effects of genes on several aspects of thinking such as attention, memory, decision making, problem solving, learning, and emotional feelings, and investigate the ways in which genetic information affects addictive behaviors and substance abuse. In addition, researchers will study how genes may explain differences in imaging data in substance users. Objectives: - To collect genetic information for research on genetic aspects of addiction and substance abuse. Eligibility: - Adults age 18 or older - (1) healthy, non-drug-using nonsmokers, - (2) healthy smokers, - (3) healthy individuals dependent on other commonly abused drugs, and - (4) individuals with other psychiatric disorders. - Participants must be enrolled in another National Institute on Drug Abuse, Intramural Research Program imaging protocol. Design: - This study involves one to two visits to National Institute on Drug Abuse, Intramural Research Program that may be separate from the participant's current research protocol study visits or on the same day as those visits. - Participants will provide a blood sample and complete questionnaires about mood, memory, and learning. - Participants may also be asked to do a few tasks, such as playing computer games involving coin tosses and money management, or responding to questions on a computer screen.
Background: - Magnetic resonance imaging (MRI) scans must be performed according to specified sets of parameters that provide optimal images of each organ and each area of the body. These scanning parameters are often specific to the institution or organization at which they are employed, and may also depend on the manufacturer of the MRI scanning equipment. Because MRI scanning equipment is always being updated and upgraded, researchers are interested in developing new and optimized scanning parameters for MRI scans. Objectives: - To improve current methods and develop new techniques for magnetic resonance imaging. Eligibility: - Individuals 18 years of age and older who are either volunteers or current NIH protocol participants. - Participants must not have any medical history factors (e.g., extreme claustrophobia, history of metal implants) that would prevent them from receiving MRI scans. Design: - Participants will have at least one MRI scan that will last from 20 minutes to 2 hours (most scans will last between 45 and 90 minutes). The total time commitment for most visits will be approximately 4 hours from start to finish. - Some MRI techniques require standard monitoring equipment or specific procedures during the scanning, such as an electrocardiogram. - Participants will have blood samples taken at the time of the scan. Some MRI studies will require the use of a contrast agent that will be administered during the scan. - Volunteers may be asked to return for additional MRI scans over the course of a few years. Follow-up scans may be done on the same part of the body or on different parts of the body. No more than one MRI scan will be performed in any 4-week period for this protocol....
The purpose of this study is to determine whether rebreathing for a short time (a bit like breathing into a paper bag) will stimulate faster breathing and thus make the giving of Oxygen more effective. The hypothesis is that the investigators method (rebreathing) will be faster than the current method of administering Oxygen.
Transient lower esophageal sphincter relaxations (tLESr) are the main mechanism of gastro-oesophageal reflux disease. They occur without any deglutition in patients but also in healthy volunteers. They are induced by meal. The gold standard to detect tLESr is esophageal manometry using perfused Dentsleeve probe. Esophageal high resolution manometry with solid state sensors was developed in the 90s. The examination is easier and more accurate than perfused manometry. The aim of this study is to validate in healthy volunteers the use of high resolution manometry (Sierra Scientific Instruments, California CA) to detect tLESr.
The purpose of the study is to determine whether the excretion of renal water- and salt-channels in the urine reflects the handling of water and salt in the kidneys, and whether the excretion can be used to monitor and/or predict the effects of treatment of certain heart or lung diseases.
Raltegravir is the first of a new antiretroviral class. A better profile of metabolic toxicity is expected. In order to better define its effects, without interference with other drugs, a study on healthy volunteers is warranted.
The Hematology Branch of the National Heart, Lung, and Blood Institute is doing a variety of laboratory research experiments that require blood and tissue samples from healthy volunteers. This protocol provides a mechanism for collecting these tissue samples. Research includes studies of normal and abnormal formation of blood cells, viral blood diseases, the role of the immune system in marrow failure and genetic risk factors for aplastic anemia. Healthy normal volunteers 8 years of age and older may be eligible for this study. Samples are collected as follows: - Blood samples: Participants 8 years of age and older donate up to 4 tablespoons of blood, which is obtained from a needle placed in an arm vein. - Participants 8 years of age and older donate a buccal mucosa sample (cells from the inside of the cheek). The inside of the cheek is scraped gently with a nylon brush. - Participants 18 years of age and older donate a bone marrow sample. The bone marrow is obtained from the hip bone. The skin over the area is wiped clean with alcohol and iodine, and then a local anesthetic is injected under the skin and also into the bone. When the area is numb, a bone marrow aspiration needle is introduced through the bone surface into the marrow. The marrow cells are collected using a syringe connected to the needle.
This study will describe the phenotype (physical and behavioral traits) of overweight and obese people. It will characterize the hormones, metabolism, food preferences, fitness and physical activity levels, sleep patterns and thought processes in people with and without weight problems. Genetic material will be collected for studies of the internal codes that influence body weight. People over 18 years of age from all weight categories (lean, overweight, obese) who are reasonably healthy may be eligible for this study. Participants undergo the following tests and procedures: - Physical exam, electrocardiogram, blood and urine tests, instructions for recording food intake for 7 days - Metabolic studies for menstruating women. - Resting metabolic rate to study how many calories the body burns at rest. - Mixed meal test to measure hormones such as insulin that regulate blood sugar. - Glucose tolerance test to determine how sensitive the body is to insulin. - 24-hour energy expenditure to measure the amount of oxygen breathed in and the amount of carbon dioxide breathed out. - Repeat 24-hour energy expenditure. - Diurnal blood sampling and temperature assessment to study the body s internal clock. - Air-displacement plethysmography (Bod Pod) to measure body composition. - Dual energy x-ray absortiometry (DEXA) to measure body fat and bone density. - Repeat Bod Pod and DEXA. - Anthropometric measurements and bioelectrical impedance to measure height, weight, and circumferences, skinfold thickness, fluid status and percentage body fat. - Bromide dilution to measure the amount of water not in cells in the body. - Doubly labeled water to measure the amount of calories burned in a 7-day period. - 24-hour diet reports. - Endothelial reactivity to measure how the blood vessels stretch or dilate for assessing cardiovascular health. - Treadmill or bicycle exercise capacity test. - Physical activity monitor. - Unicorder to detect any breathing difficulties that may interfere with sleep. - Fat and muscle biopsy to look for variations in gene expression in fat tissue and muscle. - Neurocognitive testing to check memory, decision-making, hand-eye coordination, and reasoning. - Evaluation of mood problems and assess personality type. - Evaluation to assess the quantity and quality of pain experienced. - Taste testing to determine the response to bitter, salty, sweet and sour substances. - Occupational therapy evaluation to explore the subject s adaptations, if any, for performing personal, social or professional activities; the subject s views on his or her weight, body size and shape, and strategies to control weight.