View clinical trials related to Healthy Volunteers.
Filter by:Healthy volunteers aged 18-75 will undergo hyperpolarized 3-Helium MRI and pulmonary function testing for the development of tools to assess image signal to noise and reproducibility of spin-density and diffusion-weighted imaging.
The aim of this study is to assess the behavior of a model probiotic strain, Lactobacillus salivarius, in the digestive tract of healthy volunteers and of ileostomized patients, depending on its galenic form. Two classic forms will be tested (powder and pill). An innovative galenic form (pill with retarded release), developed to enhance intestinal viability and probiotic efficacy, will also be tested.
Performing physical exercise alters the body's homeostasis, and recuperative techniques seek to anticipate and potentiate the body's recovery. One of the ways to demonstrate a recovery of the organism is the resumption of autonomic cardiac modulation analyzed through heart rate variability (HRV), a method of global assessment of the behavior of the autonomic nervous system. Among the recovery techniques, massage is the most widely used technique in sports. Therefore, the objective of the study will be to measure the effects of massage as a recuperative technique on autonomic cardiac modulation at different moments of application. It will be a randomized clinical trial where there will be five stages of evaluation. In the first stage, the behavior of the baseline HRV will be evaluated, in the second stage the behavior of the HRV in front of the massage, in the third stage the behavior of the HRV in front of the stress protocol, in the fourth stage the HRV behavior after the stress protocol and immediately after Execution of the massage and finally in the 5th stage where the HRV behavior will be evaluated after the stress protocol and the massage application will be performed at the moment of HRV recovery. The stress protocol will be composed of squats followed by jumps and wingate test, and massage by slides in the anterior thighs and posterior trunk. The HRC indexes in the time domain, frequency domain and Poincaré plot, as well as cardiorespiratory parameters and a questionnaire on individual touch perception will be analyzed. The descriptive statistical method will be used and comparisons of cardiorespiratory parameters and HRV indices will be performed using the analysis of variance technique for repeated measures model in the two factor scheme. The level of significance will be p <0.05 for all tests.
The study is a pharmacodynamic random order cross-over trial investigating the physiological effects of intra-arterial infusion of nitrite following a haemolysed autologous blood transfusion.
Background: Most medications that treat depression take weeks or months to work. Researchers want to develop fast-acting treatments. One dose of ketamine has a rapid antidepressant effect. For most people, this lasts a week or less. Repeated doses of ketamine may help maintain this effect. Objective: Main Study: To study the effects of ketamine in treating depression. Ketamine Metabolites Substudy: To study how ketamine effects brain chemistry. To study how ketamine effects the brain. This is done by looking at metabolites, which are created when a drug is broken down. Eligibility: Main Study: People ages 18-65 with major depressive disorder and healthy volunteers Ketamine Metabolites Substudy: Healthy volunteers ages 18-65 Design: Main Study: Participants will be screened in another study, with: - Medical and psychiatric history - Psychiatric and physical exam - Blood, urine, and heart tests Participants will be inpatients at NIH for 4 phases totaling 14-20 weeks. Phase I (2-7 weeks): - Gradually stop current medications - MRI: Participants lie and perform tasks in a machine that takes pictures of the body. - Mood and thinking tests - Blood and urine tests - Sleep test: Monitors on the skin record brain waves, breathing, heart rate, and movement during sleep. - Transcranial magnetic stimulation: A coil on the scalp gives an electrical current that affects brain activity. - Stress tests: Electrodes on the skin measure reactions to loud noises or electric shocks. Phase I tests are repeated in Phases II and III and in the final visit. Phase II (4-5 weeks): - 4 weekly IV infusions of ketamine or a placebo during an MRI or MEG. For the MEG, a cone over the head records brain activity. Phase III (optional): - 8 infusions of ketamine over 4 weeks Phase IV (optional): - Symptoms monitoring for 4 weeks - Participants will have a final visit. They will be offered standard treatment at NIH for up to 2 months. Ketamine Metabolites Substudy: Participants will be screened in another study, with: - Medical and psychiatric history - Psychiatric and physical exam - Blood, urine, and heart tests Participants will be inpatients at NIH for 4 days. Study Procedures: Mood and thinking tests Blood and urine tests 1 infusion of ketamine Spinal tap and spinal catheter: Used to get samples of cerebrospinal fluid (CSF). This is a fluid that moves around and within the brain and spinal cord. Studying CSF will help us learn how ketamine effects brain chemistry
Recently, the investigators have demonstrated a novel hyperpolarized helium tagging Magnetic Resonance Image (MRI) technique that is capable of directly, in vivo, and non-invasively measuring physiological lung deformation on a regional basis. This unique imaging technique holds great promise for assessing, validating, and improving the use of Deformable image Registration (DIR) algorithms in the lung. Our long term aim is to apply hyperpolarized gas tagging MRI to study lung biomechanics, develop more physiologically sound DIR algorithms for the lungs, and eventually improve radiotherapy of lung cancer. The overall aim of this application is to optimize the hyperpolarized helium tagging MRI technology and establish its usefulness for DIR assessment. Our first objective is to develop and optimize a methodology based on 3 Dimensional (3D) hyperpolarized helium tagging MRI of healthy subjects, for directly measuring lung deformation between inhalation and exhalation. Our second objective is to develop physiologically sound digital thorax phantoms based on helium-3 tagging MRI of healthy subjects and demonstrate their use for DIR assessment in the lung. These phantoms will be used to evaluate a range different DIR algorithms, by comparing the errors between the DIR-derived deformation vector fields and the ground truth represented in the digital phantom. Successful completion of these aims will yield a novel methodology for DIR assessment in the lung for radiotherapy.
One reason people gain weight is eating more calories from food than what they need for energy over 24 hours. Metabolism is the amount of energy a person uses over 24 hours. Researchers want to study the relationship between changes in metabolism and how much a person eats. Objectives: To see how much food a person eats when the body's temperature is cooled. To study how changes in metabolism may alter the amount of food a person eats. Eligibility: Healthy people ages 18-55. Design: Participants will stay at NIH for 20 days. During the first 4 days, participants will have: - Medical exam - Electrocardiogram - Blood and urine tests. One blood test includes drinking a sugar solution. - DXA body composition scan - Questions about foods they like, physical activity, and personal behavior - Exercise test on a stationary bicycle Participants will spend 24-hour periods in a metabolic chamber. The chamber will be at normal room temperature or cooler. Some times, participants will eat a diet that matches their daily needs. Other times, they can eat as much as they wish from a vending machine. Participants will have blood and urine collected. Participants will swallow an ingestible wireless sensor and wear a small data recorder device. On the second to last day, participants will stay in the metabolic chamber but only consume water and non-caffeinated sugar-free beverages. Participants will come back for 1-day visits at six months and one year from the first admission. They will have blood and urine tests, and a DXA scan. They will answer questions on physical activity and food habits.
This project studies memory and attention in healthy children aged from 5 to 17 years. The processes investigated are short term memory (auditory and visual) and attention. To characterize these processes involved in childhood, neuropsychological and neurophysiological assessments will be performed (using Electro-encephalography measures, behavioural responses and questionnaires).
This study will clinically evaluate a newly developed respiratory monitor - pneuRIP. The pneuRIP uses Respiratory Inductance Plethysmography (RIP) bands to measure key breathing indices non-invasively. This study compares the pneuRIP to an existing Respitrace system (Carefusion, Yorba Linda CA). 10 normal children and 10 children with breathing difficulties will be monitored with both systems.
The purpose of the study is to investigate spatial orientation in weightlessness as it manifests not in perception but rather in motor performance by direction and reaction time of flip switch. Hypotheses are that flip switch: 1. will be biased towards visual allocentric cues when those are available; 2. will be biased towards the egocentric reference when tactile cues are added; 3. will be dominated by egocentric cues when visual cues are not available; 4. will be delayed and more variable when confirmatory gravitational cues are absent; 5. will be faster and more reliable in absence of conflicting gravitational cues, and even more so when tactile cues are added; 6. The difference will be more pronounce when tested under Dual-task condition