Clinical Research Directory

Investigating the Analgesic Potential of (2R,6R)-HNK in Acute Pain in Healthy Volunteers

Background: Opioid drugs are often prescribed for acute and chronic pain. But these drugs are addictive, and they lead to more than 14,000 overdose deaths in the United States each year. Researchers want to find new drugs that relieve pain but are not addictive. This study will test whether a single dose of an experimental drug called (2R,6R)-hydroxynorketamine (HNK) can help reduce short term pain in healthy adults. HNK is related to ketamine. Studies suggest HNK might be as effective as ketamine at reducing pain but that it might have fewer side effects. In this study we will test how HNK affects pain and emotion. The results of this study may help us understand whether HNK has pain relieving effects and how it works in the brain, which could inform future pain treatments. Objective: To test the study drug \[(2R,6R)-hydroxynorketamine (HNK)\] for treating acute pain in healthy people. Eligibility: Healthy people aged 18 to 60 years. Design; Up to 92 healthy volunteers between 18 and 60 years old without chronic pain or psychiatric conditions will participate in the study. The study will take place at the NIH Clinical Center in Bethesda, Maryland. Each participant s involvement will last up to two months. The overall study is expected to last about three years (36 months). The study has 2 parts. In part 1, participants will have up to 2 clinic visits. They will be screened and have blood draws to make sure they're eligible for the study. They will complete sensory testing and have MRI brain scans. Sensory testing involves feeling and rating painful and non-painful sensations. These may include hot or cold temperatures, pinches or squeezes, and being touched with brushes or pinpricks. Eligible participants will have an imaging scan that shows brain activity: During the scan, they will rate heat, hear pleasant or unpleasant sounds, and view unpleasant or pleasant pictures. After completing part 1, eligible participants will be invited to part 2, which includes overnight stays at NIH. In part 2, participants will be assigned to either a treatment group or a no-treatment group. The treatment group will have 2 overnight visits of 2 nights each. The visits will be 1 to 3 weeks apart. For one of the visits, treatment group participants will receive the study drug HNK. For the other visit, they will receive a placebo. A placebo looks just like the study drug but contains no medicine. HNK and placebo are given through a tube inserted into a vein in the arm. The sensory tests, blood draws, and MRI scans will be repeated at each visit. Participants will not be told whether they got the drug or placebo on each visit. The nontreatment group will have 1 overnight visit. They will not receive the drug or placebo. The sensory tests, blood draws, and MRI scans will be repeated. Participants cannot drink alcohol, use recreational drugs, or take certain other kinds of medicine or supplements during the study.

Mechanism of Non-invasive Magnetic Stimulation

Background: Transcranial magnetic stimulation (TMS) is form of non-invasive brain stimulation. It is approved to treat depression. TMS may help decrease drug craving. It is important to understand how TMS affects the brain. Such a better understanding would help to design ways to treat drug addiction. Objectives: To learn how TMS affects the brain when it stimulates an area in the front of the brain. Also, to see how the stimulation affects the area stimulated and other connected areas. Eligibility: Healthy, right-handed adults ages 18-60 who are non-drug users. Design: Participants will be screened under protocol 06-DA-N415. Participants will have at least 3 visits. The first visit will last about 3 hours. All other visits will last up to 6 hours. Participants cannot use drugs or alcohol at least 24 hours before a visit. They cannot have more than half a cup of a caffeinated drink at least 12 hours before a visit. Each visit will include a brief medical history update, urine test for drugs and pregnancy (if female), a breath test for alcohol and smoking, and questionnaires. Participants will have a TMS orientation visit. A wire coil will be placed on the head. An electrical current will pass through the coil to create a magnetic pulse that stimulates the brain. The other visits will include 2 sessions of TMS-MRI. Participants will lie on a table that slides into a cylinder. The TMS coil and the MRI coil will be placed over the head. Pictures will be taken of the brain with and without stimulation. Participants will complete a questionnaire about how they feel before and after each TMS session and in a follow-up call 1-3 days after their last session.

A Study to Evaluate ALN-4285 in Adult Healthy Volunteers

The purpose of this study is to: * evaluate the safety and tolerability of single ascending doses of ALN-4285 in healthy volunteers * characterize the single-dose pharmacokinetics (PK) of ALN-4285

Placebo Effect of Immediate Kinesio Taping on Upper Extremity Performance in Healthy Adults

This study investigates whether Kinesio Taping has immediate effects on upper extremity performance in healthy adults and whether these effects may be influenced by placebo mechanisms. Participants are randomly assigned to one of three groups: therapeutic Kinesio Taping, sham Kinesio Taping, or no intervention. All participants complete tests of hand function, including grip strength, typing performance, reaction time, and manual dexterity, before and after a short standardized waiting period. Participants also rate their perceived performance, comfort, and overall change. The purpose of this study is to investigate the immediate effects of therapeutic Kinesio Taping on objective upper extremity motor performance and perceived function in healthy adults, and to determine whether perceived improvements correspond to measurable changes in motor performance.

Safety and Pharmacokinetics Study of Multiple Ascending Doses of VV913 Capsules

This study is a single-center, randomized, double-blind, placebo-controlled, dose-escalation trial to assess the safety, tolerability, pharmacokinetics （PK） of multiple doses of VV913 in Chinese healthy adult participants.

Measuring the Effects of Neurostimulation on Risky and Ambiguous Decision-Making Capacity in People With and Without Substance Use Disorder

Background: The purpose of this study is to understand how a type of brain stimulation, transcranial magnetic stimulation (TMS), may help those who use opioids such as heroin or methadone. TMS uses brief magnetic pulses to affect brain activity, and is approved by the FDA to treat some mental health problems and substance use. We will evaluate how TMS may help make it easier to make certain kinds of decisions that could help one manage their opioid use. Our findings may provide support for the use of brain stimulation as a treatment to reduce opioid use. Objective: To understand how TMS affects brain activity associated with decision making in people who do and do not use opioids. Eligibility: People aged 18 to 60 years with an OUD. Healthy volunteers are also needed. Design: Participants will have up to 3 clinic visits over 1 to 3 months. All participants will be screened to check if they are eligible to take part in this study. This study is completed in two parts. All eligible participants will complete the first part of the study. In the first part, you will receive one baseline magnetic resonance imaging (MRI) scan so we can take pictures of your brain while you complete computer tasks in the scanner. In these tasks, you will be asked to identify colors of words, view different images and play a game in which you can win money. If you can safely receive TMS, you will be invited to complete the second part of the study. In this part of the study, you will receive TMS and MRI over 2 sessions. For TMS, a coil will be placed on your head and a short electrical current will pass through the coil to create a magnetic pulse that stimulates your brain. You will also repeat the MRI scan and computer tasks. During one of the TMS visits you will receive active or real TMS. In the other, you will receive sham or placebo TMS, which feels like real TMS but does not affect the brain. You will receive both types of TMS. In all sessions, your urine and breath will be tested for drugs and alcohol, and you will complete questionnaires about mood and health....

Study of Food Effects of VV913 Capsules in Chinese Healthy Volunteers

This study is a single-center, randomized, open label, 3×3 crossover design to assess the high-fat meal and the standard meal effects on PK of a single oral dose of VV913 in healthy adult volunteers.

Characterization of Phenotypic and Genotypic Regressors for Imaging

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....

Phase I Trial of High-Density Theta Burst Stimulation (hdTBS)

Background: Transcranial magnetic stimulation (TMS) uses magnetic pulses to affect brain activity. A type of TMS called theta burst stimulation (TBS) is approved to treat people with major depression. Researchers have developed a new form of TBS called high-density TBS (hdTBS). They hope hdTBS will work better than TBS. But first they need to test the new treatment in healthy adults. Objective: To test hdTBS in healthy adults. Also, to compare the aftereffects of hdTBS and TBS. Eligibility: Healthy adults aged 22 to 60 years. Design: Participants will have 4 clinic visits over about 3 to 4 weeks. They must abstain from drugs and alcohol and limit caffeine before visits. At their first visit, participants will be oriented to TBS. They will wear a cap and earplugs. A device with round coils will be placed near their head. When a brief electric current passes through the coil, it generates a magnetic pulse that stimulates the brain. Participants may feel a pulling sensation on the skin under the coil. Their fingers may move involuntarily. At their next 3 visits, participants will receive either TBS or sham TBS. A sham TBS uses a low magnetic field to minimize the effects of the treatment. Participants will have up to 9 electrodes placed on 1 arm. These electrodes will measure the electrical activity in their muscles. Each TBS session will be videotaped. At every visit, participants will answer questions about their health, including substance use. They will perform 2 tasks to test their thinking skills. They will perform a test on a computer to test their reaction time....

Cytapheresis of Volunteer Donors

Background: \- National Institute on Aging researchers are looking at studies that require large numbers of white blood cells for lab use. Standard blood samples do not provide enough white blood cells for these studies. Researchers want to use cytapheresis to collect white blood cells from volunteer donors. This procedure can collect larger amounts of white blood cells and reduce the amount of fluid and other cells that are lost. Objectives: \- To use cytapheresis to collect white blood cells for study. Eligibility: \- Healthy blood donors at least 18 years of age. Design: * Participants will be screened according to the usual blood donation procedures. * Participants will provide white blood cells through cytapheresis. The blood cells will be collected in a machine that separates the white blood cells from the rest of the blood. The rest of the blood will be returned to the donor. * Participants may have this type of donation every 56 days (six times per year). They will be asked to become a repeat donor. A donation schedule may be set up. * Once a year, participants will have blood tests to continue to be eligible as a donor.

A Trial to Assess TEV-56286 at Different Doses in Healthy Participants

The purpose of the trial is to evaluate the pharmacokinetics, safety, and tolerability of TEV-56286 at different doses. The main objective is to describe how TEV-56286 is absorbed, distributed, and removed from the body (the pharmacokinetics) following administration of TEV-56286 in single doses of increasing amounts and multiple doses in healthy participants. A secondary objective is to assess the safety of TEV-56286 and how well it is tolerated. The estimated duration for participants in Part 1 with Single Ascending Dose is approximately 58 days; including up to 45 days of screening, a 4-day in-clinic period, and follow-up 8+/-1 days post discharge from the clinical unit. The estimated duration for participants in Part 2 with Multiple Dose is approximately 64 days; including 45 days of screening, a 10-day in-clinic period, and follow-up 8+/-1 days post discharge from the clinical unit.

A Study to Evaluate the Blood Levels, Safety, and Tolerability of BMS-986368 in Healthy Chinese Participants

The purpose of the study is to evaluate the drug levels, safety and tolerability of BMS-986368 in healthy Chinese participants

A Study of LY4178256 in Healthy Participants

The main purpose of this study is to evaluate how well LY4178256 is tolerated and what side effects may occur in healthy participants. Blood tests will be performed to check how much LY4178256 gets into the bloodstream and how long it takes the body to eliminate it. For each participant, the study will last about 7 months and will include either 7 or 12 visits depending on the assigned treatment.

A Study to See How RO7763505 Works and How Safe it is When Given to Healthy People and People With Stable Heart Disease

This study will evaluate safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of single ascending doses (SAD) (Part 1a), multiple ascending doses (MAD) (Part 1b), and the food effect (Part 1c) of RO7763505 in healthy adult participant. In Part 2, the safety, tolerability, PK and PD of multiple doses of RO7763505 in participants with stable coronary artery diseases (CAD).

Study to Assess Adverse Events and How Oral Emraclidine Moves Through the Body of Adult Healthy Volunteers

The objective of this study is to evaluate the pharmacokinetics (PK) and relative bioavailability of emraclidine following single oral administration of different immediate-release (IR) tablet formulations in healthy adult participants.

A Pilot of Pediatric/Adult Study of Gene Expression Profiling and Clinical Characterization of Phototoxicity

This study will examine the phototoxicity, a reaction to light that is like exaggerated sunburn, which occurs in people who take medications such as voriconazole, a medication used to fight fungus. Sunscreens might protect the skin from the reaction. Although phototoxicity from voriconazole is not completely understood, it may be related to how that medication is metabolized in the liver by enzymes called cytochrome P450 enzymes-and mainly by one known as 2C19. A way to evaluate phototoxicity is through microarrays, which measure how much each gene is expressed in cells from tissues such as skin. Patients ages 8 and older who are scheduled to begin taking or who currently take voriconazole may be eligible for this study. Also, patients ages 18 to 45 in good health who have skin tone known as Type 2, which usually burns and tans only slightly following sun exposure, may be eligible. All patients will visit the Dermatology Clinic. They will complete two questionnaires, on medical history and medications, as well as the skin response to sunlight, and donate about 3 teaspoons of blood. Patients who are scheduled to take voriconazole will visit the clinic four times, that is, two visits 2 consecutive days before beginning the medication and two visits on 2 consecutive days after taking it for at least 7 days. Each visit will take 1 to 2 hours. Patients about to take voriconazole will have a blood test and undergo a physical exam of the skin test site, on the buttocks. Researchers will take photographs of the specific site and do tests to measure skin reaction to ultraviolet (UV) light. UV light will be shined on 15 small areas of the skin, each 1 x 1 centimeters. After 24 hours, any redness that occurs on the skin will be checked. Afterward, patients will begin taking voriconazole according to directions by the researchers. At 10 or more days later, patients will visit the clinic. Sunscreen will be applied and 1 hour later after administration of voriconazole, a blood sample will be drawn to check the level of medication. Then UV light will be shined on 23 areas of skin 1 x 1 centimeters. More photographs will be taken of test sites to record changes in skin redness. On the next day, the skin response will be evaluated. Participants in the control group will be asked to avoid UV radiation by wearing hats and clothing, and using sunscreen. They will be given the doxycycline, an antibiotic, and undergo procedures with UV light shined on small areas of the skin, on the buttocks. Control participants will have 7 study days, with visits lasting from 1 to 3 hours and probably not exceeding 8 hours. They will have two shave biopsies on Study Day 2 and on Study Day 7 to determine how the skin has responded to UV light exposures.

Collection of Tissue Specimens From Patients With Solid Tumors or Blood Disorders and Their HLA-Compatible Family Members

This study will collect biological samples for use in research experiments aimed at better understanding the clinical features of certain diseases. The specimens may be used to evaluate the effectiveness of known therapies, refine treatment approaches, identify potential new therapies, and explore opportunities for disease prevention. The following individuals 2 years of age or older may be eligible for this study: * Patients with a cancerous solid tumor or a cancerous or non-cancerous blood disorder who are being screened for or who are enrolled in a treatment study at the NIH Clinical Center * HLA-compatible donor family members (18 years of age or older) of the above patients who are being evaluated for or are enrolled in an NIH study as a stem cell transplant donor * Patients with a cancerous solid tumor or a cancerous or non-cancerous blood disorder or a bone marrow failure condition who cannot participate in an NIH treatment protocol or travel to the NIH Clinical Center and who are referred for participation through their home health care provider. Research samples will be collected from participants when blood is drawn or bone marrow, urine, or stool is collected, or tumor or other tissue is biopsied as part of their general medical care. Investigators may periodically request an additional sample of blood, stool, or urine. Participants who are 18 years of age or older may donate a large number of white blood cells through a procedure called leukapheresis. This procedure is not part of general medical care and would be done for research purposes only. For apheresis, a catheter (plastic tube) is placed in a vein in the subject's arm. Blood flows from the vein into a cell separator machine, where the white cells are separated from the red cells, platelets, and plasma by a spinning process. The white cells are removed and collected, and the rest of the blood is returned to the subject through a second tube placed in the other arm. ...

Collection and Analysis of Blood, Bone Marrow, and Buccal Mucosa Samples From Healthy Volunteers

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.

Vitamin E Pharmacokinetics and Biomarkers in Normal and Obese Women

Background: * Vitamin E is an antioxidant that reduces the damaging effects of oxygen in the body. Most American men (90%) and women (96%) do not get enough vitamin E from their diets; however, the amount of vitamin E needed by the body has been studied only in men, not women. In addition, it is unknown whether another antioxidant, vitamin C, helps vitamin E in protecting the body. Because vitamin E is a fat-soluble vitamin, how much body fat a person has could affect the amount of vitamin E needed for protection. Objectives: This study has three arms to examine vitamin E requirements: * To determine the amount of fat required to get the best vitamin E absorption from a meal. * To determine the amount (i.e., best dose) of vitamin E that must be consumed before it can be measured in the blood. * To examine how vitamin E and vitamin C work together in the body, in conjunction with diet and vitamin supplements. Eligibility: * Arms 1 and 2: Women between the ages of 18 and 40 years who have a normal weight and body mass index (BMI) of 27 or less. * Arm 3: Women between the ages of 18 and 40 years who have a normal weight (BMI 27), who are overweight (BMI \> 27), or who are overweight (BMI \> 27) and have non insulin-dependent diabetes. Design: * Arm 1: Five studies, each lasting 1 month with 1 month off between studies (total study = 10 months). Participants will take 500 1,000 mg of vitamin C twice daily for 2 weeks before admission to the clinical center for 1 week. * Study 1: Participants will eat breakfast containing a known amount of fat, after which they will take a vitamin E pill as well as receive an IV injection of vitamin E. Other foods contain only negligible amounts of vitamin E. Blood and urine samples will measure levels of vitamin E and other substances. * Studies 2 5: Outpatient visits will consist of the same tests as in Study 1; however, the amount of fat in the breakfast will range from 0% to 40% in random order. During one of the studies, an adipose tissue biopsy will be collected to determine how much vitamin E is in the tissues. * Arm 2: Five studies, each lasting 1 month with 1 month off between studies (total study = 10 months). Preparation for Arm 2 is the same as in Arm 1. The proportion of fat, muscle, and water in the body will also be measured. * Study 1: Participants will eat breakfast containing 30% fat, after which they will take a vitamin E pill as well as receive an IV injection of vitamin E. Conditions and procedures are the same as in Arm 1. * Studies 2 5: Outpatient visits will consist of the same tests as in Study 1; however, the amount of vitamin E in the breakfast will range from 2 to 30 mg in random order. * Arm 3: Outpatient (2 to 6 weeks) and inpatient studies (4 to 6 weeks). * Outpatient study: Participants will take 500 1,000 mg of vitamin C daily and provide blood and urine samples, as well as an adipose tissue sample. * Inpatient studies: Two vitamin E inpatient studies. Before these begin, participants vitamin C blood levels will be reduced by means of a diet low in vitamin C. Blood tests will determine how quickly vitamin C leaves the body. Once the vitamin C level is reduced, the first vitamin E study will begin. Study A: The procedure for this study is the same as in Arm 2, Study 1. Study B: The procedure for this study is the same as in Study A, except that the participants blood vitamin C levels will be higher. ...

Study of Cognitive and Behavioural Biases in People With Idiopathic Environmental Intolerance (IEI) Versus Healthy Controls

Symptoms that patients attribute to the environment when no environmental cause can be identified are known as "idiopathic environmental intolerance" (IEI). IEI is often associated with a major psychological and socio-professional impact. Specific diagnostic tools and evidence-based treatment programs are still lacking. As a result, IEI patients often feel left behind by physicians and public health policies. A number of environmental agents are singled out by IEI sufferers, including chemicals (cleaning products, tobacco smoke), electromagnetic fields generated by cell phones and base stations, air conditioning and infrasound emitted by wind turbines. Patients hold one or more of these environmental agents responsible for a very wide range of chronic, non-specific physical symptoms such as diffuse pain, fatigue, dizziness, dyspnoea, hot flushes, nausea, tinnitus or palpitations, but also cognitive symptoms such as loss of memory or concentration. However, the medical examination of IEI patients shows no evidence of bodily dysfunction. Furthermore, numerous exposure studies have shown that environmental agents did not alter the biological parameters of IEI patients, that patients could not reliably distinguish between real and fictitious exposures, and that they only presented symptoms when they thought the exposure was real, whether this was true or not. This suggests that IEI symptoms can be considered "functional", resulting from an alteration in the way the body is felt rather than from injury to the body itself. Recently, several authors including Lemogne and Pitron have proposed a cognitive model of body awareness and more specifically of functional physical symptoms.This model is part of a Bayesian understanding of brain function, which is increasingly seen as a process underlying all perceptual experiences.From this perspective, bodily experiences are the result of probabilistic calculations Two sources of information are integrated, weighted by their reliability (accuracy) with regard to the current context: the body's sensory signals on the one hand (i.e. peripheral nerve inputs) and "priors" about the body on the other (i.e. pre-existing information from previous bodily experiences, beliefs about the body, emotions, etc.). In functional physical symptoms, it has been suggested that priors override the body's sensory signals, thus skewing bodily perception.This would be the consequence of an imbalance between low-precision sensory signals on the one hand, and high-precision priors on the other. In line with this model, Van den Bergh and Witthöft have proposed an understanding of IEI as arising from a nocebo effect.Here, we propose a research project with patients suffering from IEI to test and validate this Bayesian theoretical model of IEI, the main study C22-19, BELIEFS which is currently recruiting. This ancillary study, C24-26 BELIEFS-VS, enables us to include a population of healthy volunteers whom we will compare with the IEI patients in the main C22-19 BELIEFS study.

Neurobiology of Suicide

Background: There are no good treatments for people considering suicide. Researchers want to study suicide with questions, blood tests, brain imaging, and sleep studies. They hope to better understand suicide, so they can help suicidal people. Objective: To understand what happens in the brain when someone has thought about or attempted suicide. Eligibility: Group 1: Adults ages 18 70 who have thought about or attempted suicide recently Group 2: Adults ages 18 70 who have thought about or attempted suicide in the past Group 3: Adults ages 18 70 who have depression or anxiety, but have never thought about suicide Group 4: Healthy volunteers the same ages. Design: Participants will be screened in another protocol. Adults who have recently thought about or attempted suicide must be referred by a doctor. They may do up to 3 phases of this study. Groups 2, 3 and 4 will do only Phase 1 and will not get ketamine. Phase 1: 1 week in hospital. Participants will have: Physical exam. Questions about thoughts and feelings. Thinking and memory tests and simple tasks. Blood and urine tests. Two MRI scans. Participants will lie on a table that slides into a metal cylinder that takes pictures. They will have a coil over their head and earplugs and do a computer task. Sleep test. Disks and bands will be placed on the body to monitor it during sleep. Magnetic detectors on their head while they perform tasks. A wrist monitor for activity and sleep. Lumbar puncture (optional). A needle will collect fluid from the back. Shock experiments (optional). Participants will observe pictures and sounds and feel a small shock on the hand. Phase 2: 4 days in hospital. A thin plastic tube will be placed in each arm, one for blood draws, the other to get the drug ketamine once. Participants will repeat most of the Phase 1 tests. Phase 3: up to 4 more ketamine doses over 2 weeks. Participants will have follow-up calls or visits at 6 months and then maybe yearly for 5 years.

Children s Growth and Behavior Study

Background: \- Studies show that many factors affect children's eating behavior and health. These include sleep, mood, thinking skills, and genetics. Studying children over time may identify children at higher risk for eating-related health concerns. Objective: \- To understand how genes and environment influence eating behavior and health over time. Eligibility: \- Children ages 8-17 in good general health. Design: * Screening visit 1: Medical history, physical exam, body measurements, and questions. * 14 days: Participants will wear a wrist monitor and answer smartphone prompts about eating and mood. They may give a stool sample. * Screening visit 2: * Body measurements. * Saliva, urine, and blood samples. * Heart tests. * Meals provided (after fasting overnight). * Questionnaires and interview. * Behavior, thinking, and exercise tests. * X-ray of left wrist and full body.\<TAB\> * Some parents may have medical history, physical exam, and questions at screening visits. They may answer questions at the yearly visits. * Participants will have up to 6 yearly visits. They will give a urine sample and body measurements, and repeat the X-rays. They will have questions and behavior and thinking tasks. They may give stool samples. Visits will range from 3 to 8 hours. * Participants may choose to participate in other studies: * Stress and Hormones, 1 visit: While resting, participants will give saliva samples and have their heart monitored. Then they will do math. They will repeat the resting part, then do a computer task. * Brain Imaging, 2 visits: Twice, participants will perform tasks with a magnetic cone on their head then answer questions. Once, they will have an MRI, lying still in a scanner with a coil on their head. Before the first visit, participants will collect at-home saliva samples once a day for three days. During both visits, participants will perform tasks and answer questions that gauge their thinking skills and mood. * Experiment 3 (sleep/fatigue): Participants will complete 2 additional visits. During these visits, participants will complete a task on the computer for 2 hours, or watch a movie for two hours. After completion of the task/movie, they will answer questions and be provided with food. Participants will be compensated for the time and inconvenience involved with completing study procedures.

The Body's Affect on Vitamin C

Pharmacokinetics is the term used for how the body affects a drug once it is taken. Vitamin C, also known as ascorbic acid, is an essential water soluble vitamin. Meaning, the body does not make Vitamin C it must be taken in through the diet. In this study researchers will attempt to determine how the amount of water consumed affects the level of vitamin C in the blood (specifically the plasma component of the blood). In this study researchers will take 13 subjects and place them on a Vitamin C restricted diet. Vitamin C levels will be measured twice a week on an outpatient basis until all subjects reach a desired low level of Vitamin C (12-15 micromolar plasma ascorbic acid concentration). Subjects will then be admitted and undergo 24 hour blood and urine collection. Following the collection of samples, subjects will then begin to receive Vitamin C orally (by mouth) and intravenously (injected into the vein). The dosage of Vitamin C will gradually increase from 30 mg-2500 mg divided into two daily doses. Blood and urine samples will be collected each time the dose is increased. The study will take approximately 18 weeks after which the subjects will be discharged in healthy condition.

Imaging Techniques in MRI

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.