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Filter by:Background: - Direct current (DC) brain polarization is a technique in which very weak electricity is applied to the head. Doctors have used DC polarization for many years on patients and healthy people with no known serious side effects. Earlier, researchers found that DC polarization can temporarily improve the ability of healthy people to think of certain words. - A disadvantage of existing methods of DC polarization is that they use large electrodes and the current spreads over a large area of the brain. This makes it difficult to target particular brain areas. High-density DC polarization uses several small electrodes to focus the current in a small area of the brain. This study will test high-density DC polarization for the first time in humans. Objectives: - To see how well high-density direct current polarization works in the brain. - To test a new method of performing direct current brain polarization. Eligibility: - Healthy, right-handed adults, ages 18 and older, who have no history of neurological or psychiatric illnesses. Design: - After an initial screening visit with clinical examination, participants may be assigned to one or both experiments of the study. - Experiment 1: Participants will have electrodes placed on the left side of their heads, and will be asked to say aloud as many words as they can think of that begin with certain letters. After the high-density DC polarization current is turned on and run for 10 minutes, participants will say words beginning with a different set of letters and perform reaction time and thinking speed tests. Some participants will receive real polarization and others will not, although all participants will be told that they are receiving the polarization. - Experiment 2: Participants will have DC brain polarization performed with transcranial magnetic stimulation (TMS), which uses magnetic pulses to activate nerve cells in the brain. We will use TMS to help us understand how far the effect of DC polarization spreads in the brain. After attaching electrodes to a point on the scalp above the ear, researchers will give about 50 TMS pulses to five different places near this area. These pulses will produce some painless muscle twitches in the hand or arm. The TMS pulses will be followed by the DC brain polarization, and then by another set of TMS pulses to see if there are any differences in muscle response.
This study will evaluate the safety and efficacy of the experimental malaria vaccine AMA1-C1/Alhydrogel® (Registered Trademark) and determine whether a new, additional component of the vaccine may increase its effectiveness. Malaria is a debilitating and potentially fatal blood disease transmitted by a parasite found in certain mosquitoes. The AMA1-C1 vaccine has been designed to create an immune response against the parasite and prevent the disease. The purpose of the study is to determine whether the additional component-protein pieces known as CpG- improves the immune response to the vaccine without causing problematic side effects. Volunteers must be healthy adults between 18 and 45 years old. Individuals who have had malaria in the past or have recently traveled to areas where malaria is endemic will be excluded from the study. Candidates will be screened with a physical examination, blood tests, and medical history. Participants will be involved in a three-stage study. In the first stage, a group of participants will receive either a high dose of the vaccine alone or a low dose combined with the CpG protein. In the second stage, a different group of participants will receive a high dose of the vaccine alone or a high dose combined with CpG. In the third stage, a larger group of participants will receive a high dose of the vaccine alone or a high dose combined with CpG. The vaccine will be injected into the muscle of the upper arm, and all participants will receive three doses of the vaccine with 28 days between doses to monitor possible reactions and side effects. Participants will be monitored for 30 minutes after each injection and will record any symptoms they experience over the six days after receiving their dose. In addition, participants will be examined over the course of six months during and after the trial with physical exams and blood and urine tests.
This study will examine abnormalities in mitochondria (energy-producing machinery of cells) and in genes related to mitochondria in the blood cells, muscle, and fat of HIV-positive patients who are taking nucleoside reverse transcriptase inhibitors (NRTIs) and in patients not currently taking HIV medications, and compare the results to healthy volunteers. Many patients with HIV infection take NRTIs to help control the infection. These medications may damage cell mitochondria, possibly causing side effects such as fatigue. This study will explore the relationship between changes in mitochondria and related genes and patient reports of energy level, mood and quality of life. Healthy volunteers and HIV-infected patients between 18 and 55 years of age may be eligible for this study. Healthy volunteers must test negative for the HIV antibody. HIV-positive patients must have been diagnosed positive for at least 1 year. Patients who are taking antiretroviral therapy must have been taking the same drug regimen (with at least two NTRIs and no protease inhibitors) for at least 3 months. HIV positive patients not taking antiretroviral medication must not have had antiretroviral therapy for at least 1 year. Candidates are screened with a medical history, brief physical examination, blood and urine tests, and questionnaires related to mood and energy. Qualified volunteers will undergo the following procedures during three or four study visits: Visit 1 Complete history and physical examination, blood tests, and questionnaires about energy level, mood, and quality of life. Visit 2 Muscle and fat biopsy: Before the biopsy, blood is drawn to check blood counts and to test for pregnancy in women who can become pregnant. The biopsy is done on an outpatient basis in the operating room. The site of the biopsy (an area on the upper arm or upper leg) is numbed with an injection under the skin. A 1-inch incision is made over the muscle to be biopsied and a small sample of muscle tissue and small sample of fat are removed. The incision is then closed and bandaged. Following the biopsy, you will be monitored for about 4 hours in the clinic. Strenuous physical activity should be restricted in the week following biopsy to allow healing. Visit 3 Examination of biopsy site and possible apheresis: The biopsy site is examined for healing. Apheresis may be scheduled for this visit or for an extra visit between the biopsy and the final visit. This procedure for obtaining white blood cells for study is optional. For apheresis, blood is withdrawn from a needle placed in a vein in the arm and the white cells are separated from the rest of the blood. The white cells are extracted and the red cells and plasma are then returned to the body through a second needle.
This study will test the safety of an experimental vaccine intended to prevent West Nile virus (WNV) infection and determine if it causes side effects. WNV symptoms may vary from fever and headache, to a polio-like syndrome with paralysis. Infection rarely results in death. The vaccine used in this study contains DNA that instructs the body to produce a small amount of a protein found in WNV. If the body creates resistance or immunity to these proteins, then the vaccine may protect against WNV. Study participants cannot get WNV from the vaccine. Healthy volunteers between 18 years and 50 years of age may be eligible for this study. Candidates are screened with a medical history, physical examination, and blood and urine tests, including a pregnancy test for women who can become pregnant. Patients undergo the following tests and procedures: - Vaccine injections: Vaccines are given as injections in the upper arm, using a needleless system called the Biojector 2000. The first injection is on study day 0, the second on day 28 (+/-) 7 days, and the third on day 56 (+/-) 7 days. There must be at least 21 days between injections. The pregnancy test for women of childbearing potential is repeated the day of each vaccine injection. - Diary card: Participants are given a 5-day diary card after each injection to record their temperature and any symptoms and side effects they may experience for up to 5 days after the injection. The diary cards are returned to the clinic at visits scheduled 2 weeks after each injection. Side effects and symptoms also must be reported immediately to a study nurse or doctor, and a clinic visit may be required for an examination. - Clinic visits: At day 0 and weeks 2, 4, 6, 8, 10, 12, 24 and 32, participants have a medical history, physical examination (if needed) and blood tests. Vital signs and weight are also recorded. Lymph nodes are examined at day 0 and weeks 2, 4, 6, 8, 10 and 12, and urine samples are collected at day 0 and weeks 2, 4, 6, 8 and 10. Some of the blood drawn during this study is used for genetic tests to see if different types of immune response to a vaccine are related to genetic differences in people.
This study will examine how nitrite infusions affect exercise tolerance (how much a person can exercise before having to stop). Exercise ability is limited by how fast oxygen can be delivered to the body and how fast the body can produce energy. Both of these processes are affected by nitric oxide (NO), a gas produced by cells that line blood vessels. NO is important in regulating blood vessel dilation, and consequently, blood flow. Nitrite may act as a storehouse for nitric oxide and be able to improve exercise tolerance. Healthy normal volunteers between 21 and 45 years of age who can use an exercise bicycle may be eligible for this study. Candidates are screened with a medical history, physical examination, electrocardiogram, breathing tests, blood tests, and a pregnancy test for women who are able to bear children. Pregnant women are excluded from the study. The screening session includes practice exercise on the bicycle. Participants exercise on a stationery exercise bicycle for about 30 minutes on each of two study days. During the test, they breathe in and out of a mouthpiece that allows inhaled and exhaled respiratory gases to be measured. Before subjects begin to exercise, a small tube is placed in the artery of their forearm inside the elbow. A longer tube called a central line is placed in a deeper vein in the neck after the area has been numbed. A thinner tube, called a pulmonary artery catheter, is placed through the central line and advanced into the chambers of the heart, through the heart valve, and into the lung artery. This catheter measures various pressures directly in the heart and lungs. Blood samples are drawn through the catheter also, to avoid the need for multiple needle sticks. Another tube is placed in the vein of the other arm to deliver medications. Thirty minutes after all the tubes are placed, a blood sample is drawn for baseline measurements. Then, either saline (sterile salt water) or nitrite is injected into the tube in the arm vein. Thirty minutes after the injection, the subject starts exercising on the bicycle. The work setting on the bicycle is increased every minute, and the subject pedals until he or she is too tired to continue. During the test, a small blood sample is collected every 2 minutes. Heart rate, blood pressure, and heart rhythms are continuously monitored. After the test on the first day, participants are admitted to the hospital to rest for the remainder of the afternoon and evening. The tubes are kept in place for the following morning, when the procedure is repeated exactly as before, except that subjects who received saline the first day are given nitrite the second day, and vice versa.
This study will explore the risks and causes of Parkinson's disease, a chronic progressive nervous system disorder. Patients typically have tremors, muscle weakness and a shuffling gait. Patients with Parkinson's disease, their relatives and healthy volunteers may be eligible for this study. Candidates must be 18 years of age or older. Patients whose parkinsonism is due to a secondary cause, such as infection or injury, and healthy volunteers who have a first degree family member (parent, grandparent, child, sibling) with Parkinson's disease are excluded from enrollment. Participants are asked about possible symptoms they may have and about their general health. They provide a blood sample to obtain DNA for genetic analysis to look for genetic differences that might be related to risks for Parkinson's disease. White blood cells may be treated in the laboratory to grow a cell line, which provides a source of substances in the blood without having to draw samples repeatedly.
This study will examine the effect of transcranial magnetic stimulation (TMS) on short-term memory in healthy adults. Healthy people use their brains to answer short-term memory questions in a different way than do patients with schizophrenia. Attention and memory deficits in schizophrenia patients significantly hamper their recovery and rehabilitation, yet there are no effective treatments for these impairments. TMS is a method of brain stimulation that may be able to change the electrical activity of the nerve cells of the brain and improve certain brain functions. This study will explore the effect of TMS on memory and perhaps discover brain processes that may be helpful in developing new ways to treat schizophrenia. Healthy volunteers between 18 and 55 years of age, excluding pregnant women, may be eligible for this study. Participants undergo the following tests and procedures: - Medical history, physical examination, blood tests, electrocardiogram (EKG), and urine pregnancy test for women of childbearing age. - Magnetic resonance imaging (MRI) and functional MRI (fMRI). These tests are done in participants who have not had structural and functional MRIs as participants in NIMH's 2-day schizophrenia study within 90 days of entering the current study. MRI is done to locate the place in the brain to simulate with TMS and fMRI is done to look at brain activity while the subject solves short-term memory tasks. Both tests are done at the same session. Before the scan, four vitamin E capsules are taped to the subject's scalp. After the capsules are in place, the subject lies on a stretcher that is moved into the scanner - a narrow cylinder with a strong magnetic field. During the scan, subjects are asked to do some simple tests, such as watching pictures on a screen or pressing buttons in response to numbers they were shown a few seconds earlier. Scanning may take up to 2 hours, but usually lasts between 45 and 90 minutes. - TMS. For this procedure, subjects receive either active TMS or a sham procedure (placebo) that imitates TMS but does not use real electrical stimulation. For TMS, an insulated wire coil is placed on the scalp and a brief electrical current is passed through it. This generates magnetic pulses that travel through the scalp and skull and cause small electrical currents in the cortex, or outer part of the brain. The stimulation may cause muscle twitching in the scalp or face and may also cause small movement of the limbs. During the procedure, electrodes are taped to the scalp to record the electrical activity of the brain while short-term memory is tested. Two tests make up a set. There are a total of six test sets; each set takes about 3 minutes. Five periods of electrical stimulation are delivered before each test set. Each period of stimulation lasts 5 seconds, followed by a 10-second rest period. The stimulation-rest intervals continue until five periods of TMS have been applied. For the memory test, subjects press a key on a computer keyboard as quickly and accurately as possible in a test of their ability to remember a string of numbers, or letters. - Questionnaires. At the beginning and end of the TMS session, participants fill out questionnaires that assess their mood, ability to concentrate, and level of anxiety.