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Discover 23,284 clinical trials near Maryland. Find research studies in your area.
Showing 22761-22780 of 23,284 trials
NCT00001543
This is a study investigating the hormones and substances important to the stress response. The hormone that is most directly responsible for stress response is called corticotropin-releasing hormone (CRH). CRH is produced in the hypothalamus of the brain and causes the pituitary gland to produce another hormone called ACTH. The hormone ACTH then acts on the adrenal glands causing them to produce the hormone cortisol. Unfortunately, CRH levels are unable to be measured in simple blood samples. However, substances like cortisol and leptin can provide information as to the activity of the hypothalamus. The hormone leptin is associated with the regulation of body weight and the normal maintenance of bodily functions (homeostasis). It is found in fat cell (adipocyes) and communicates the nutritional status of the body to the brain (central nervous system). Research using animals has shown that defects in the communication between leptin and the brain causes obesity (the state of being overweight). It has also been noted that obese humans tend to have high levels of leptin. By studying patients with abnormal genes responsible for leptin production, researchers have found that a least one leptin gene must be intact for the normal secretion of hormones to proceed. These results show that the hormone leptin is produced outside of the brain in fat cells and acts directly on the function of the hypothalamus within the brain. Researchers believe that leptin plays a key role in the normal release of hormones from the HPA axis. Researchers intend on continuing to study the role of leptin in fat distribution, and the activity of the HPA axis in normal volunteers. In addition, this study will focus on the role of leptin in depression, because depression is characterized by changes in food intake, body weight, and neuroendocrine function. Data gathered from this study will provide a better understanding of the causes and medical consequences of major depression.
NCT00001647
This study will evaluate the safety and immune system effects of infusing HIV-infected patients with multiple doses of lymphocytes (white blood cells) from their non-infected identical twin. It will determine whether the donated lymphocytes can improve immune function and reduce viral load in the infected twin. Identical twin pairs-one who is infected with HIV-1 and one who is negative for the virus-may be eligible for this study. Candidates will be screened with blood tests, a medical history and physical examination. Both twin participants will receive a tetanus booster shot, if needed. The non-infected twin will undergo apheresis to collect white blood cells. For this procedure, whole blood is collected, similar to the procedure for donating a unit of blood from a needle in the arm. The blood flows through a cell separator machine where the white cells are removed, and the rest of the blood (red cells, plasma and platelets) is returned to the donor through a catheter in the opposite arm. The collected lymphocytes will be given intravenously (through a vein) to the infected twin over a 60-minute period. This procedure-apheresis and infusions-will be repeated 4 days a week to complete one cycle. The cycles will be repeated about every 8 weeks for 6 cycles (about 1 year). The infected twin will have blood samples drawn on the first day of each cycle, 2 weeks after the beginning of each cycle, and 4 weeks after each cycle to evaluate immune status, viral load and other safety parameters. The frequency of these blood tests may change as the study progresses. The infected twin will also undergo apheresis immediately before each cycle of infusions and one month later to test the white cells for certain immune features. The number of apheresis procedures may be reduced as the study proceeds.