View clinical trials related to Primary Dysautonomias.
Filter by:The purpose of this study is to determine the cause of low blood pressure in selective patients who have problems with their involuntary (autonomic) nervous system. These patients frequently have had symptoms throughout their life, and their disorder might have a genetic basis. The biochemical, physiological and pharmacological procedures in this study should help us define the problem and perhaps lead to more effective treatment.
It has been found that in some cases, when a person with Diabetes Mellitus has an episode of low blood sugar,or hypoglycemia, and then later exercises, he or she is vulnerable to another bout of hypoglycemia during that exercise. The purpose of this study is to determine what factors during the previous bout of hypoglycemia might cause another bout of hypoglycemia while exercising later.
The purpose of this study is to determine the way by which Alprazolam (Xanax) an anti-anxiety drug affects specialized molecules in your brain called GABA (A) receptors that alter your body's ability to defend itself from low blood sugar (hypoglycemia). We hypothesize that prior activation of GABA (A) receptors may result in blunting of counterregulatory responses during subsequent hypoglycemia and exercise.
Background: Sj(SqrRoot)(Delta)gren s Syndrome (SS) is an autoimmune disease that affects the glands that produce saliva and tears, causing dry eyes and dry mouth. Researchers do not know the exact cause of SS, but they believe that it may be caused by abnormalities in the autonomic nervous system (ANS) that stimulate these glands. Objectives: To better understand ANS function in patients with SS. To compare information about ANS function in healthy individuals and in patients with SS. Eligibility: Patients with Sj(SqrRoot)(Delta)gren s Syndrome who are 18 years of age and older, and who are not pregnant or breastfeeding. Participants will be asked to taper or discontinue the use of certain medications or dietary supplements before the ANS testing. Participants must be willing to discontinue the use of alcohol and tobacco 24 hours prior to testing. Design: The study will require one inpatient admission and/or outpatient visits to the NIH Clinical Center. The following tests and procedures will be performed: - Saliva, tear, and sweat production measurements to evaluate the function of glands. - Testing of changes to the cardiovascular system, including blood pressure and blood flow testing, and an electrocardiogram designed to evaluate hemodynamic changes controlled by the ANS. - Testing of changes to the gastrointestinal system, including a swallowing assessment study, barium swallow study, and gastric emptying study designed to evaluate gastrointestinal function controlled by the ANS. - Tests to evaluate the ANS function in response to certain drugs (edrophonium, glucagon and acetylcholine). - Self-reported questionnaire on ANS function and emotional/psychological well-being. Additional procedures and tests may include the following: - Blood samples. - Optional skin biopsy to study sweat glands and nerve supply of the skin.
This study is designed to use PET scans in order to measure activity of the sympathetic nervous system. The sympathetic nervous system is the portion of the nervous system that maintains a normal supply of blood and fuel to organs during stressful situations. PET scan or Positron Emission Tomography is an advanced form of an X-ray. It is used to detect radioactive substances in the body. During this study researchers plan to inject small amounts of the radioactive drug fluorodopamine into patients. Fluorodopamine is very similar to the chemicals found in the sympathetic nervous system. It can attach to sympathetic nerve endings and allow researchers to view them with the aid of a PET scan. One area of the body with many sympathetic nerve endings is the heart. After giving a dose of fluorodopamine, researchers will be able to visualize all of the sympathetic nerve endings involved in the activity of the heart. In addition, this diagnostic test will help researchers detect abnormalities of the nervous system of patient's hearts.
Brain and nerve cells communicate with each other by releasing and picking up chemicals called neurotransmitters. Norepinephrine is a neurotransmitter used by part of the nervous system activated during stress called the sympathetic nervous system. The sympathetic nervous system is involved with regulating blood pressure and pulse rate. Researchers believe the level norepinephrine in the blood can be used to measure activity of the sympathetic nervous system. This study is designed to answer important questions about rates of release of norepinephrine into the blood stream, removal of released norepinephrine, and the sympathetic nervous system response to stress. Researchers will attempt to measure levels of norepinephrine and activity of the sympathetic nervous system in patients with high blood pressure, normal patients with family histories of high blood pressure, patients taking drugs that can effect levels of norepinephrine, and patients with diseases or conditions directly affecting the sympathetic nervous system.
This study involves sampling blood from both normal volunteers and patients with diseases known or suspected to involve body chemicals called catecholamines. The blood will be used to establish normal values for plasma levels of catecholamines and related neurochemicals; to test for abnormal neurochemical patterns in patients; and to establish a "bank" of DNA from normal volunteers and from patients to be used in future studies about possible alterations of catecholamine-related genes. Study participants will report to NIH after fasting overnight except for water or noncaloric, noncaffeinated beverages. They must not have taken Tylenol for at least 5 days. Blood will then be drawn. DNA will be extracted and stored in the freezer for future studies.