View clinical trials related to Normal Physiology.
Filter by:Background: - The way that the body burns calories is known as energy expenditure. Some studies show that when we are cold, we burn more calories to keep our bodies warm. Brown fat is a special kind of fat that can use energy to keep the body warm. Small animals and infants have been known to have brown fat for many years. Recently, it has been suggested that adult humans also have brown fat. If brown fat becomes active (burns calories) in adult humans when exposed to cold, then these people would tend to burn off more calories and might not gain weight easily. Learning more about the relationship between energy expenditure, brown fat, environmental temperature, and body temperature may help explain why some people become obese and other people do not. Objectives: - To better understand how the body burns calories when exposed to different temperatures. - To study brown fat and how it burns calories in cold temperatures. Eligibility: - Healthy men between 18 and 35 or 55 and 75 years of age. - Healthy women between 18 and 35 years of age. - To control for ethnicity, participants must be non-Hispanic whites or African Americans. Design: - Participants will be screened with a physical exam and medical history. Blood and urine samples will be collected. - Participants will stay in the Metabolic Unit of the National Institutes of Health Clinical Center as inpatients for no more than 14 days. The length of the hospital stay will depend on how participants respond to the different study temperatures. - Every afternoon, participants will walk for 30 minutes on a treadmill. All meals will be provided. - Participants will stay up to 5 hours per day in a specialized room with different temperature settings. Temperatures will range from about 61 degrees to 88 degrees Fahrenheit. Body temperature, activity, calorie burning, and cold/hot sensations will be monitored. On the study day of the coldest temperature, participants will have an imaging study to look for brown fat activity. - Participants will be compensated for their time and participation at the end of the study.
Background: - Magnetic resonance imaging (MRI) studies provide important information on the structure and function of various body systems, including the brain, muscles, joints, heart, and blood vessels. Scientific applications of MRI scans often use techniques that need to be modified or refined before they are used in clinical studies. To develop and modify these techniques for the new Philips 3T Achieva whole-body MRI scanner, researchers are interested in conducting trial MRI scans on healthy individuals and individuals with conditions that require imaging studies. Objectives: - To conduct preliminary trials of the 3T MRI facility to develop and refine MRI scanning procedures. Eligibility: - Individuals at least 18 years of age who are able to have magnetic resonance imaging. Design: - Participants will be screened with a full medical history and physical examination, as well as blood and urine tests. - Participants will have an MRI scan using the 3T scanner. Some scans may require the use of a contrast agent or radiotracer, which is a small amount of radioactive substance that will be injected before the start of the scan. Some participants may be asked to perform tasks of thinking and movement while in the scanner, in order to test the procedures required for a functional MRI scan. - No treatment will be provided as part of this protocol.
Background: - Two areas on the surface of the brain, the dorsolateral prefrontal cortex (DLPFC) and motor cortex (MC), play a key role during learning. Researchers are interested in determining the effect that transcranial magnetic stimulation (TMS) on the DLPFC and MC has on participants' performance of learning tasks. By studying the effect of TMS on reaction time, learning, and memory, researchers hope to better understand how to treat conditions such as Parkinson's disease and traumatic brain injury that affect these parts of the brain. Objectives: - To study the effects of transcranial magnetic stimulation on the dorsolateral prefrontal cortex and motor cortex. - To learn which areas of the brain are used to perform certain learning and memory tasks. Eligibility: - Healthy, right-handed individuals between 18 and 70 years of age. Design: - Participants will be screened with a physical and neurological examination and a medical and psychiatric history. - Participants will be asked to take part in one of five different parts of this study. Most participants will have four 2-hour visits to the National Institutes of Health Clinical Center. Some participants (those involved in Part 5) will have only one 2-hour visit. - Parts 1 and 2 (four visits): Participants will have TMS, and then do a learning task that may provide a small monetary reward. On the first visit, before the TMS, participants will take an intelligence test based on reading aloud the words given on a card. Participants who have not had a routine magnetic resonance imaging (MRI) scan of the brain within the past year will also have a scan. - Parts 3 and 4 (four visits): Participants will have a functional MRI scan while doing a learning task that may provide a small monetary reward. On the first visit, before the functional MRI, participants will take an intelligence test based on reading aloud the words given on a card. Participants who have not had a routine magnetic resonance imaging (MRI) scan of the brain within the past year will also have a scan. - Part 5 (one visit): Participants will take an intelligence test based on reading aloud the words given on a card. Then, participants will have TMS followed by a functional MRI scan. During the functional MRI, participants will do a button-pressing task that may provide a small monetary reward. - Participants will also be asked to provide a small blood sample for genetic analysis.
Background: - Bacteria and other micro-organisms in the intestines play important roles in immunity and other health conditions. As a result, these micro-organisms are likely to affect many health conditions, including several types of cancer. Because cancer and other diseases may affect the digestive system and the bacteria within it, fecal samples that are taken both before and after the onset of a disease may show important changes in the body and provide information about possible treatments. However, unlike repositories of blood and tissue samples, researchers do not have a repository of fecal specimens. Researchers are interested in determining whether standard collection procedures used for fecal occult blood testing can provide accurate information on micro-organisms in the intestine. Objectives: - To determine whether standard fecal occult blood testing procedures can provide accurate collections of fecal micro-organisms for research purposes. Eligibility: - Healthy volunteers at least 18 years of age. Design: - At the clinical center, participants will be provided with written and illustrated instructions for the collection procedures and a self-administered risk questionnaire. The questionnaire will assess the challenges of collecting fecal specimens and will collect data on major dietary restrictions (e.g., vegan, vegetarian, food allergies), medication use and major illnesses, knowledge of and past experience with fecal occult blood testing, colonoscopy and colon cancer, and the fecal collection devices. - Participants will be provided with a collection bag for the sample, 16 sample collection tubes, and a box with frozen gel packs. - On the morning of collection, participants will collect the fecal sample in the bag and use the collection tubes to obtain material from different parts of the stool. - The tubes will be sealed and placed in the box with the gel packs, and the participant will hand deliver the entire box to the clinical center. - Characteristics of the bacteria in the material will be measured by laboratories at the University of Maryland. - Statistical comparisons will determine how well the procedures worked.
Background: - Many treatments for immune system disorders involve the use of stem cells that have been collected from blood marrow. To obtain these stem cells without surgery, individuals receive granulocyte colony-stimulating factor (G-CSF) to encourage the production of stem cells that can be collected through blood donations. However, not all patients or normal donors respond to G-CSF alone. - Plerixafor, recently approved by the Food and Drug Administration, is different from G-CSF but also allows stem cells to be collected from donated blood. However, more research is needed on the quality and viability of the stem cells collected after using both G-CSF and plerixafor. Objectives: - To collect and study the blood cells produced after treatment with G-CSF and plerixafor in healthy volunteers. Eligibility: - Healthy volunteers between 18 and 65 years of age who are eligible to donate blood. Design: - Participants will be screened with a medical history, physical examination, and initial blood tests. - At the start of the study cycle, participants will receive daily morning injections of G-CSF for 5 days. These may be given at the clinical center or by the participant after teaching, depending on the participant s preference. - On the morning of Day 4, participants will visit the clinical center to provide a blood sample after the injection. On the evening of Day 4, participants will receive an injection of plerixafor. - Participants will have the final injection of G-CSF on the morning of Day 5, and will provide another blood sample. - On Day 5, participants will have apheresis to separate the stem cells from the rest of the blood. The apheresis may take up to 5 hours to complete. - The study will end after a follow-up phone call 7 to 14 days after the apheresis procedure.
Background: - Incidence of breast cancer is very low in Mongolia (6.6/100,000), especially in rural areas. Over the past 15 years, there has been considerable economic growth in Mongolia, resulting in migration to urban centers such as the capital, Ulaanbaatar, from areas with nomadic or semi-nomadic lifestyles. This recent migration offers an opportunity to study the endocrine profiles of premenopausal women as they acculturate to a more Western lifestyle. Objectives: - To obtain new data on premenopausal endocrine and growth factor concentrations to assess possible variations by migration status within Ulaanbaatar; that is, to compare women who have been living in Ulaanbaatar for the longest period of time with those who have recently moved to Ulaanbaatar. - To compare data from Mongolia with data from the United States (and possibly China), where women are at higher risk of breast cancer. Eligibility: - A sample of 375 premenopausal women will be drawn from a larger sample of mothers whose children are participating in a study conducted by Harvard Medical School. Only mothers of girls will be included in this cross-sectional study. Women ages 25 44 years who are not pregnant or breastfeeding are eligible. Design: - A total of 30 ml (three 10 ml samples) of whole blood will be collected. Women will be asked to provide a spot urine sample. These samples will be sent periodically to the NCI biorespository during the course of the study for testing. A portion of a sample for each participant will be kept in Ulaanbaatar in case of problems in delivery to the United States. - The following hormones will be evaluated: testosterone, androstenedione, dehydroepiandrosterone (DHEA), DHEA-sulfate, estrone, estradiol, estriol, progesterone, prolactin, placental lactogen, IGF-1 and IGFBP-3, VEGF, soluble endoglin, and possibly other angiogenic proteins. - Socioeconomic status and medical and lifestyle information will be assessed by questionnaire, including ethnicity, occupation, education, and migration status (e.g., whether she moved from a rural area and time since migration). Breast cancer risk factors such as age at first pregnancy, age at first menstruation, gravidity (total number of pregnancies), parity (total number of childbirths), smoking status, alcohol use, and dietary intake will also be determined. (These questionnaires will have been pilot tested and revised before the start of this study.) The Global Physical Activity Questionnaire, developed by the World Health Organization, will assess physical activity. - Mean and median premenopausal hormone concentrations of previously collected blood samples from women in the United States who are at high breast cancer risk will be compared with the Mongolian samples. In addition, Chinese data will be compared if available.
This study will examine whether genetic differences among individuals affect blood levels of certain chemicals called DBPs after showering. Chemicals such as chlorine and ozone are used to kill germs in water. These chemicals may react with organic matter in the water and form other chemicals called disinfection byproducts, or DBPs. Although people are usually exposed to DBPs by drinking tap water, these chemicals may also penetrate the body during showering. This study will see whether the levels of DBPs after showering vary among individuals depending on differences in genes that code for enzymes called GSTT1, CYP2D6, and CYP2E1, which break down DBPs. This study, sponsored by the Centers for Disease Control and Prevention and the National Institutes of Health, is conducted at the University of Pittsburgh's Center for Clinical Pharmacology. Healthy adults between 18 and 45 years of age who do not smoke cigarettes and are not taking any medicines may be eligible for this study. Candidates are screened with a medical history and blood and urine tests. Participants are given a diary to record the foods they eat and how much water they drink during the 2 days before their study appointment. The following activities are scheduled on the appointment day: - Measurements of blood pressure, height, and weight, and pregnancy test for women - Questions about alcohol consumed and medications taken in the last 48 hours - Review of food and water diary - Interview for demographic information (name, address, date of birth, etc.) and other information, such as sex, height, weight. Subjects are also asked about anything, such as exercise, that might affect their breathing, since breathing problems are a rare side effect of chlorzoxazone, a drug used in this study. - Urine sample collection - Blood draw and insertion of a small catheter (plastic tube) to allow for additional blood draws during the test procedure without having repeated needle sticks - 10-minute shower in a private bathroom - Blood sample collection 10 minutes after the shower and again at 30 minutes after the shower - Dose of chlorzoxazone (a drug used to treat muscle pain) - Interview about subject's exposure to water - Light breakfast - Blood and urine collections 2 hours after the chlorzoxazone dose - Lunch - Observation for drug side effects for 2 hours, or longer if needed Seven blood samples totaling 75 milliliters (about 5 tablespoonfuls) of blood are collected during this study. The blood is tested for chemicals called trihalomethanes to see how they are broken down. The urine samples are tested for chemicals called haloacetic acids, which are found in tap water after it has been treated with chlorine.
Objectives: Plasma levels of catechols have distinct meanings in terms of indicating functions of endogenous catecholamine systems. This Protocol is designed to enable ongoing quality assurance of diagnostic and research assays of catechols and their metabolites and to identify possible influences of demographic and anthropometric factors, dietary constituents, and conditions of sampling on reference values. Study Populations: The study population is healthy volunteers and people who are obese or have untreated hypertension. Design: Arm venous blood is drawn via an indwelling i.v. catheter from healthy volunteers across demographic and anthropometric spectra (age, gender, skin color, ethnicity, body mass, adiposity), to obtain quality control plasma and establish reference values for plasma levels of catechols and their metabolites. Non-invasive physiological measures are obtained concurrently. Levels of catechols and their metabolites are related to results of common clinical pathology tests. Subgroups of subjects are tested more than once, to assess dietary influences (cereal with milk, coffee) and conditions of sampling (temperature at the skin). Outcome Measures: The main non-experimental outcome is an ongoing pool of quality control plasma. The main experimental outcome measures are plasma concentrations of catechols and their metabolites, non-invasive physiological measures, and results of common clinical pathology tests. Subject groups are compared with respect to the above demographic and anthropometric factors. Effects of the experimental manipulations are assessed within subjects
This study will use magnetic resonance spectroscopy (MRS) to measure in the brain the transfer of [13]C as it is naturally metabolized from glucose to specific chemical transmitters. From this method, we can measure the rate of production of an important excitatory neurotransmitter (glutamate) as well as an inhibitory neurotransmitter (GABA).
The purpose of this study is to use brain imaging technology to compare differences in brain structure, chemistry, and functioning in individuals with brain and mental disorders compared to healthy volunteers. Schizophrenia is a brain disorder that results from subtle changes and abnormalities in neurons. These deficits likely occur in localized regions of the brain and may result in widespread, devastating consequences. The neuronal abnormalities are inherited through a complex combination of genetic and environmental factors. Brain imaging technologies can be used to better characterize brain changes in individuals with schizophrenia. This study will use magnetic resonance imaging (MRI) scans to identify predictable, quantifiable abnormalities in neurophysiology, neurochemistry and neuroanatomy that characterize schizophrenia and other neurological and neuropsychiatric disorders.