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Discover 23,284 clinical trials near Maryland. Find research studies in your area.
Showing 17121-17140 of 23,284 trials
NCT00076466
This study will determine: 1) whether learning a task with the dominant hand is accompanied by changes in the area of the brain that controls hand movement, and 2) how the brain is able to make these changes. Previous studies have shown that practicing a motor task can change brain excitability, but it is not known how well brain excitabilities are changed during motor learning. This study will measure changes in activity of the part of the brain that controls hand movement before, during, and after exercising the hand on a response pad. Healthy normal volunteers between 18 and 40 years of age may be eligible for this study. Candidates who have not been evaluated at NIH within the past year will be screened with a brief interview about their current state of health and clinical and neurological examinations. Participants will undergo the following procedures: Learning a finger movement/reaction time task For this procedure, participants sit in front of a computer monitor with the index, middle, ring, and little fingers placed flat on four corresponding buttons of a response pad. They are asked to press one of the four buttons as fast as they can in response to an asterisk displayed on the monitor. The position of the asterisk indicates which button to push. Subjects perform nine sets of 120-button pushes with a 15-minute rest between each set. During the rest period, subjects undergo transcranial magnetic stimulation (described below), which causes twitches in the hand muscles. The electrical activity corresponding to the twitches is recorded by attaching electrodes (small metal disks) to the skin over the hand muscles. Transcranial magnetic stimulation For this test, an insulated wire coil is held over the scalp. A brief electrical current passes through the coil, creating a magnetic pulse that electrically stimulates the brain. The subject hears a click and may feel a pulling sensation on the scalp under the coil. The stimulation may also cause twitching in the muscles of the face, arm, or leg. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. ...
NCT00327067
Blood donors who have a low fingerstick hemoglobin level are usually deferred from donating. A possible solution to the problem of repeated deferrals might be for Blood Banks to offer donors with low hemoglobin levels oral iron supplements. To determine the feasibility of such a program, this study will: * Determine the frequency of iron deficiency in first-time and repeat blood donors * Examine the effects of long-term blood donation on donor hemoglobin levels and iron stores * Compare body iron stores in donors who have low hemoglobin values with that of donors who have acceptable hemoglobin values at the time of donation * Determine what conditions other than iron deficiency lead to low hemoglobin levels in blood donors * Determine the safety and effectiveness of giving oral iron tablets to donors with low hemoglobin levels * Monitor the effect of oral iron administration on donor satisfaction and donor retention. First-time and repeat blood donors at the NIH Clinical Center Blood Bank 18 years of age and older may be eligible for this study. Participants include prospective donors who have an acceptable hemoglobin value at the time of donation and those whose hemoglobin level is determined to be too low for donation. All participants do the following: * Answer medical questions about their diet, health, and family history of blood disorders. * Have blood samples drawn from their arm for testing blood cell counts, iron stores, and other hemoglobin-related tests as appropriate. Donors with low hemoglobin also: * Take iron supplements (ferrous sulfate) to replenish iron stores. (Donors who have previously had unpleasant side effects from ferrous sulfate are offered ferrous gluconate as an alternative.) * Undergo evaluation with medical screening and laboratory tests at the time of future blood donations.