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Discover 17,868 clinical trials near Massachusetts. Find research studies in your area.
Showing 16441-16460 of 17,868 trials
NCT00538070
The NMDA receptor has been identified as having a role in substance use disorders as well as in schizophrenia. One example of the former is nicotine's effect on dopaminergic activity not only by increasing the release of dopamine in the Midbrain reward centers, but also through less direct mechanisms affecting alpha-7 nicotinic receptors, NMDA receptors, and Glycine, a co-agonist for the NMDA receptors. In terms of schizophrenia, it has been hypothesized that NMDA receptor hypofunction plays a role in the mechanism for negative symptoms and cognitive dysfunction in these patients. The NMDA hypofunction may be reversed with increased synaptic glycine availability. Sarcosine, or n-methyl-glycine, is a GlyT-1 and System A transport inhibitor actions which could be expected to increase the availability of glycine, in the synaptic space. Sarcosine is a dietary supplement which could be found in several food items such as egg yolks and turkey. Our collaborative team has developed a novel, non-invasive magnetic resonance spectroscopy (MRS) technique for measuring brain glycine changes that allows us to study glycine homeostasis. The purpose of this study is to explore the effect of sarcosine (n-methyl-glycine) on brain glycine concentrations. It is our hypothesis that oral sarcosine, at a dose of 2 grams per day, will be well tolerated and associated with increased brain glycine concentrations. It is our secondary exploratory hypothesis that increases in brain glycine will be associated with behavioral signs of increased NMDA and dopamine activity. This modulation could have future therapeutic potential for disorders of hedonic and cognitive function.
NCT00753012
The purpose of this research study is to learn about the effects of a medication called Vyvanse on the heart (cardiovascular system). The U.S. Food and Drug Administration (FDA) has approved Vyvanse for the treatment of Attention Deficit Hyperactivity Disorder (ADHD). People who have ADHD have trouble paying attention, organizing, and planning; these symptoms can cause problems at work, socially and at home. Vyvanse (also known as Lisdexamfetamine) is a stimulant class medication. There have been reports of serious cardiovascular effects in children and adults treated with stimulants. While there is no definite evidence that these events were related to the use of stimulants, the deaths have raised questions about the cardiovascular safety of stimulants. The study will involve in-depth cardiovascular tests, namely echocardiograph (ultrasound of the heart) and cardiopulmonary exercise test (also called stress test; subjects exercise on a bicycle while measuring their heart activity and breathing is monitored by cardiologists). The investigators predict to see changes in blood pressure and heart rate as shown in previous clinical studies, and that the in-depth cardiovascular tests will provide new insights into the cardiovascular impact of stimulants.