View clinical trials related to Normal Physiology.
Filter by:Background: Dopamine (DA) is a chemical signal in the brain linked to learning, memory, and habits. Stimulant drugs like methylphenidate can increase DA in the brain. Researchers want to measure DA with and without this drug. They want to learn how methylphenidate and brain dopamine affect body responses, mood, and thinking. Objective: To better understand the role of dopamine in the brain and the effects of methylphenidate. Eligibility: Adults ages 18-55 who have used alcohol or stimulant drugs but have no drug dependence. Design: Participants will be screened with: - Physical exam - Question about medical, psychiatric, and alcohol and drug use history - Questions to see if it s safe to have a PET/MRI scan - Blood and urine tests - Breath test for alcohol Participants will have 3 or 4 study visits. At each visit they will have: - Urine and breath tested for alcohol and drugs - A thin plastic tube (catheter) inserted in each arm by needle - A small amount of radioactive chemical injected through the catheter. - PET/MRI scan. Participants will lie still on a table that slides in and out of a metal cylinder surrounded by a strong magnetic field. Their vital signs will be monitored. They will get earmuffs for loud noises. Before the scan, participants will get the study drug or placebo through the catheter. They may also get a sugar pill (placebo). They will get a small meal and have blood drawn. - Tests of memory, attention, and thinking. Participants will wear an activity monitor on the wrist for one week.
Background: A radioligand is a radioactive substance that is used to diagnose diseases. A new ligand is called [11C]PS13. This has a small amount of radioactivity that can be detected by a positron emission tomography (PET) scan. If this ligand works well in this study, researchers may be able to use it to better understand and diagnose brain disorders. Objectives: To evaluate if [11C]PS13 can measure its receptor, which is involved in inflammation. To see if researchers get the same results when scanning a person twice. Eligibility: Healthy people ages 18 and older who are in Protocol 01-M-0254. Design: This study requires three visits of 2-5 hours each. Participants will have 2 PET scans with [11C]PS13. A needle will guide a small plastic tube (catheter) into an arm vein. The needle will be removed, leaving only the catheter in the vein. The ligand will be injected through the catheter. The PET scanner is shaped like a doughnut. Participants will lie on a bed that slides in and out of the scanner. Participants will wear a molded a plastic mask that fits the head. Another catheter will be put into an artery at the wrist or elbow area. Vital signs will be monitored during the PET scan. Participants will have a test during the PET scan to monitor heart function. Participants will have blood and urine tests. Participants will have 1 magnetic resonance imaging (MRI) scan. The MRI scanner is a metal cylinder surrounded by a strong magnetic field. Participants will lie on a table that slides in and out of the cylinder.
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.
Background: People can feel different levels of pain. This may depend on social, cultural, and biological factors. These factors can also influence how people respond to each other, and how they judge other people s experiences. Researchers want to learn more about these relationships. Objective: To study if social and cultural factors lead to differences in pain experience and how pain is interpreted by other individuals. Eligibility: Healthy adults ages 18-60 Design: Participants will have 1 or 2 visits. Participants will be screened with a medical history and nursing assessment. Participants may have the following: Electric shock through small sticky pads on the arm, leg, or foot. Thermal stimulation. A device called a thermode will be placed on the arm, leg, or foot. A computer controls the thermode temperature. Lowering their hand into very cold water. Videos or pictures of the face will recorded while participants get painful stimulation. A test to record heart electrical activity. Small metal disc or sticky pad electrodes will be placed on the chest. Pulse rate and breathing measured. Sweating will be measured with two small sensors stuck on the hand. A test to measure the electrical activity of facial muscles. Small metal disk or sticky pad electrodes will be attached to the skin. Viewing pictures and/or videos of other people who get painful and nonpainful stimulation. Participants will make decisions about the images. They will respond by keyboard, mouse, or button. Eye tracking. A camera will measure participants pupil size and follow their eye movements. ...
Background: The chemical messenger dopamine carries signals between brain cells. It may affect addiction. Heavy use of pain medicines called opioids may decrease the amount of dopamine available to the brain. Researchers want to study if decreased dopamine decreases self-control and increases impulsiveness. Objective: To learn more about how opiate use disorder affects dopamine in the brain. Eligibility: Adults 18-80 years old who are moderate or severe opiate users Healthy volunteers the same age Design: Participants will first be screened under another protocol. They will: - Have a physical exam - Answer questions about their medical, psychiatric, and alcohol and drug use history - Take an MRI screening questionnaire - Give blood and urine samples - Have their breath tested for alcohol Participants will have up to 3 study visits. They will have 2-3 positron emission tomography (PET) scans. A radioactive chemical will be injected for the scans. Participants will lie on a bed that slides in and out of the donut-shaped scanner. A cap or plastic mask may be placed on the head. Vital signs will be taken before and after the PET scans. Participants will get capsules of placebo or the study drug. They will rate how they feel before, during and after. Participants will have their breath and urine tested each day. Participants will have magnetic resonance imaging (MRI) scans. They will lie on a table that slides into a cylinder in a strong magnetic field. They may do tasks on a computer screen while inside the scanner. Participants will have tests of memory, attention, and thinking. Participants will wear an activity monitor for one week....
Background: Movement disorders have many different causes and symptoms. Researchers still do not fully understand which parts of the brain are involved in fine movement. They want to learn about which brain regions could be abnormal in people with movement disorders. Objective: To better understand how the brain controls movement. Eligibility: Healthy, right-handed adults age 18-70 years old. Design: Participants will be screened with a physical exam and questions about their handedness. They may have a urine test. Participants will have 1 or 2 clinic visits. The first visit will last about 1.5 hours. The second will last about 3 hours. Participants will have structural magnetic resonance imaging (MRI). A strong magnetic field and radio waves take pictures of the brain. Participants will lie on a table that slides in and out of a metal cylinder. Participants may have transcranial magnetic stimulation. A wire coil is held on the scalp. A brief electrical current is passed through the coil and creates a magnetic pulse that stimulates the brain. Participants will wear a pair of glasses or a headband with small sensors so researchers can track head position. Participants will perform a simple index finger movement task. Participants may have surface electromyography from at least two hand muscles. Small metal disk or adhesive pad electrodes will be taped to the skin. Participants will be seated in a comfortable chair with their hands placed on a pillow. Participants may have an electroencephalography. A cap with small disc electrodes will be placed on the scalp.
Background: After a stroke, the balance between the two halves of the brain can be lost. This may cause people to lose the ability to perceive a side of space. This is called neglect. Having people wear prism glasses (called PA) can reduce neglect symptoms. Researchers want to find out more about how PA, and whether it restores the balance in the brain. Objective: To learn how prism adaption temporarily changes vision and connections in the brain. Eligibility: People ages 18 75 with brain damage of the right side of the brain from a stroke or other cause, leading to neglect. Healthy volunteers ages 18 75. Design: Participants will have 1 3 visits. Participants will be screened with a neurological exam. They may also have: Tests of thinking and vision Tests to see which eye and hand they prefer A pregnancy test All participants will: Answer questions about their personality, style of thinking, and beliefs. Do simple tasks on paper or computer Have magnetic resonance imaging. They will lie on a table that can slide in and out of a cylinder in a strong magnetic field. Participants will lie still or do computer tasks in the scanner. Participants may also have: Transcranial magnetic stimulation. A brief electrical current passes through a wire coil on the scalp. This creates a magnetic pulse that affects brain activity. Participants may be asked to tense certain muscles or perform simple actions or tasks. PA. They will sit in front of a board and point to a dot on it while they wear prism glasses that shift vision to the left or right.
Background: Some people cannot make medical treatment decisions on their own. The people who make decisions on their behalf are called medical surrogates. Sometimes surrogates cannot predict which treatment course the person or their loved ones would have chosen. The surrogates often become distressed because of making these decisions. Researchers think a tool called a Patient Preference Predictor (PPP) may be able to make the process easier. The PPP would predict what treatment the person would want. This is based on treatment preferences of similar people in a similar circumstance. Researchers want to interview surrogates to explore their views on the PPP. Objective: To explore surrogates views on incorporating a PPP into shared medical decision-making. Eligibility: People 18 years or older who: Have acted as a surrogate medical decision-maker within the past 3 years. This includes decisions about treatment, medication, hospice care, hospital admission, or discharge. Are not pregnant Design: Participants will be screened by meeting with clinicians in person or by phone to discuss the study. Participants will take part in a focus group. This is a small group of people discussing their thoughts and opinions. This will last for about 2 hours. Participants will be served a light meal. Participants will provide information about themselves and their views. They will talk about their past experiences making medical decisions for someone. They will discuss how they felt about these decisions. The PPP will be explained to participants. They will give their views on it. The research team will audio record the focus group and take notes. Participants will fill out questionnaires.
Background: The immune system defends the body against bacteria and other harmful invaders. But it can overact and attack healthy cells by mistake. The group of drugs called glucocorticoids (GCs) can calm down an overactive immune system. But they often cause negative side effects. Researchers want to learn how human genes respond to GCs. Genes live inside each cell of the body. They tell our cells how to function. Researchers hope the results of this study will show them how to develop better drugs that will have the benefits of GCs without the side effects. Objectives: To study how human genes respond to glucocorticoid drugs. Eligibility: Healthy adult volunteers ages 18-64. Design: Participants will be screened with a medical history and physical exam. They will have a heart test and blood tests. The study visit will last about 6 hours. Participants will have medical history, physical exam, and 3 blood draws. Participants will have a skin biopsy. An injection will numb the skin on one arm. Then a tool will remove a piece of skin about as big as a pencil eraser. A GC cream will be applied to the other arm. Participants will get the GC study drug for 30 minutes. It will be a liquid that will drip through a needle placed in an arm vein. Participants will have a skin biopsy of the arm that had the cream applied. Participants will have follow-up calls 1 and 4 days later. They will be asked about reactions or other health problems.
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.