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5-I-R91150
5-I-R91150 (or R93274) is a compound that acts as a potent and selective antagonist of 5-HT2A receptors. Its main application is as its iodine-123 radiolabeled form, in which it can be used in SPECT scanning in human neuroimaging studies, to examine the distribution of the 5-HT2A receptor subtype in the brain, e.g. with respect to sex and age and in adults with Asperger syndrome or Alzheimer's disease. An alternative 5-HT2A receptor ligand also used in neuroimaging is altanserin Altanserin is a compound that Binding (molecular), binds to the 5-HT2A receptor, 5-HT2A receptor (5-Hydroxytryptamine (serotonin) 2A receptor). Labeled with the isotope fluorine-18 it is used as a radioligand in positron emission tomography (PET) .... References Further reading * * 5-HT2A antagonists Fluoroarenes Piperidines Iodoarenes Salicylamide ethers {{nervous-system-drug-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altanserin
Altanserin is a compound that binds to the 5-HT2A receptor (5-Hydroxytryptamine ( serotonin) 2A receptor). Labeled with the isotope fluorine-18 it is used as a radioligand in positron emission tomography (PET) studies of the brain, i.e., studies of the 5-HT2A neuroreceptors. Besides human neuroimaging studies altanserin has also been used in the study of rats. An alternative for PET imaging the 5-HT2A receptor is the [ 11C] volinanserin (MDL-100,907) radioligand. 18F-altanserin and 3H-volinanserin have shown very comparable binding. Both altanserin and MDL 100,907 are 5-HT2A receptor antagonists. 18F.html" ;"title="sup>18F">sup>18Fsetoperone can also be used in PET. An alternative SPECT radioligand is the 123I.html" ;"title="sup>123I">sup>123I 5-I-R91150 receptor antagonist. A rapid chemical synthesis of fluorine-18 and H-2 dual-labeled altanserin has been described. Other ligands for other parts of the serotonin system used in PET studies are, e.g., DASB, ke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antagonist (pharmacology)
A receptor antagonist is a type of receptor ligand or drug that blocks or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist. Antagonist drugs interfere in the natural operation of receptor proteins.Pharmacology Guide: In vitro pharmacology: concentration-response curves " '' GlaxoWellcome.'' Retrieved on December 6, 2007. They are sometimes called blockers; examples include alpha blockers, |
5-HT2A Receptor
The 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor (GPCR). The 5-HT2A receptor is a cell surface receptor, but has several intracellular locations. 5-HT is short for 5-hydroxy-tryptamine or serotonin. This is the main excitatory receptor subtype among the GPCRs for serotonin, although 5-HT2A may also have an inhibitory effect on certain areas such as the visual cortex and the orbitofrontal cortex. This receptor was first noted for its importance as a target of serotonergic psychedelic drugs such as LSD and psilocybin mushrooms. Later it came back to prominence because it was also found to be mediating, at least partly, the action of many antipsychotic drugs, especially the atypical ones. Downregulation of post-synaptic 5-HT2A receptor is an adaptive process provoked by chronic administration of selective serotonin reuptake inhibitors (SSRIs) and atypical antipsychotics. Suicidal and otherwis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodine-123
Iodine-123 (123I) is a radioactive isotope of iodine used in nuclear medicine imaging, including single-photon emission computed tomography (SPECT) or SPECT/CT exams. The isotope's half-life is 13.2230 hours; the decay by electron capture to tellurium-123 emits gamma radiation with a predominant energy of 159 keV (this is the gamma primarily used for imaging). In medical applications, the radiation is detected by a gamma camera. The isotope is typically applied as iodide-123, the anionic form. Production Iodine-123 is produced in a cyclotron by proton irradiation of xenon in a capsule. Xenon-124 absorbs a proton and immediately loses a neutron and proton to form xenon-123, or else loses two neutrons to form caesium-123, which decays to xenon-123. The xenon-123 formed by either route then decays to iodine-123, and is trapped on the inner wall of the irradiation capsule under refrigeration, then eluted with sodium hydroxide in a halogen disproportionation reaction, similar to colle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotopic Labeling
Isotopic labeling (or isotopic labelling) is a technique used to track the passage of an isotope (an atom with a detectable variation in neutron count) through a reaction, metabolic pathway, or cell. The reactant is 'labeled' by replacing specific atoms by their isotope. The reactant is then allowed to undergo the reaction. The position of the isotopes in the products is measured to determine the sequence the isotopic atom followed in the reaction or the cell's metabolic pathway. The nuclides used in isotopic labeling may be stable nuclides or radionuclides. In the latter case, the labeling is called radiolabeling. In isotopic labeling, there are multiple ways to detect the presence of labeling isotopes; through their mass, vibrational mode, or radioactive decay. Mass spectrometry detects the difference in an isotope's mass, while infrared spectroscopy detects the difference in the isotope's vibrational modes. Nuclear magnetic resonance detects atoms with different gyromagnetic r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SPECT
Single-photon emission computed tomography (SPECT, or less commonly, SPET) is a nuclear medicine tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera (that is, scintigraphy), but is able to provide true 3D information. This information is typically presented as cross-sectional slices through the patient, but can be freely reformatted or manipulated as required. The technique needs delivery of a gamma-emitting radioisotope (a radionuclide) into the patient, normally through injection into the bloodstream. On occasion, the radioisotope is a simple soluble dissolved ion, such as an isotope of gallium(III). Most of the time, though, a marker radioisotope is attached to a specific ligand to create a radioligand, whose properties bind it to certain types of tissues. This marriage allows the combination of ligand and radiopharmaceutical to be carried and bound to a place of interest in the body, where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuroimaging
Neuroimaging is the use of quantitative (computational) techniques to study the structure and function of the central nervous system, developed as an objective way of scientifically studying the healthy human brain in a non-invasive manner. Increasingly it is also being used for quantitative studies of brain disease and psychiatric illness. Neuroimaging is a highly multidisciplinary research field and is not a medical specialty. Neuroimaging differs from neuroradiology which is a medical specialty and uses brain imaging in a clinical setting. Neuroradiology is practiced by radiologists who are medical practitioners. Neuroradiology primarily focuses on identifying brain lesions, such as vascular disease, strokes, tumors and inflammatory disease. In contrast to neuroimaging, neuroradiology is qualitative (based on subjective impressions and extensive clinical training) but sometimes uses basic quantitative methods. Functional brain imaging techniques, such as functional magnet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. Physiologically, brains exert centralized control over a body's other organs. They act on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ageing
Ageing ( BE) or aging ( AE) is the process of becoming older. The term refers mainly to humans, many other animals, and fungi, whereas for example, bacteria, perennial plants and some simple animals are potentially biologically immortal. In a broader sense, ageing can refer to single cells within an organism which have ceased dividing, or to the population of a species. In humans, ageing represents the accumulation of changes in a human being over time and can encompass physical, psychological, and social changes. Reaction time, for example, may slow with age, while memories and general knowledge typically increase. Ageing increases the risk of human diseases such as cancer, Alzheimer's disease, diabetes, cardiovascular disease, stroke and many more. Of the roughly 150,000 people who die each day across the globe, about two-thirds die from age-related causes. Current ageing theories are assigned to the damage concept, whereby the accumulation of damage (such as DNA ox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asperger Syndrome
Asperger syndrome (AS), also known as Asperger's, is a former neurodevelopmental disorder characterized by significant difficulties in Interpersonal relationship, social interaction and nonverbal communication, along with restricted and repetitive patterns of behaviour and interests. The syndrome is no longer recognised as a diagnosis in itself, having been merged with other disorders into Autism spectrum, autism spectrum disorder (ASD). It was considered to differ from other diagnoses that were merged into ASD by relatively unimpaired language development, spoken language and cognitive development, intelligence. The syndrome was named after the Austrian Pediatrics, pediatrician Hans Asperger, who, in 1944, described children in his care who struggled to form friendships, did not understand others' Nonverbal communication, gestures or Empathy#Cognitive empathy, feelings, engaged in one-sided conversations about their favourite interests, and were clumsy. In 1994, the diagno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alzheimer's Disease
Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term memory, remembering recent events. As the disease advances, symptoms can include primary progressive aphasia, problems with language, Orientation (mental), disorientation (including easily getting lost), mood swings, loss of motivation, self-neglect, and challenging behaviour, behavioral issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the typical life expectancy following diagnosis is three to nine years. The cause of Alzheimer's disease is poorly understood. There are many environmental and genetic risk factors associated with its development. The strongest genetic risk factor is from an alle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5-HT2A Antagonists
The 5-HT2A receptor is a subtype of the 5-HT2 receptor that belongs to the serotonin receptor family and is a G protein-coupled receptor (GPCR). The 5-HT2A receptor is a cell surface receptor, but has several intracellular locations. 5-HT is short for 5-hydroxy-tryptamine or serotonin. This is the main excitatory receptor subtype among the GPCRs for serotonin, although 5-HT2A may also have an inhibitory effect on certain areas such as the visual cortex and the orbitofrontal cortex. This receptor was first noted for its importance as a target of serotonergic psychedelic drugs such as LSD and psilocybin mushrooms. Later it came back to prominence because it was also found to be mediating, at least partly, the action of many antipsychotic drugs, especially the atypical ones. Downregulation of post-synaptic 5-HT2A receptor is an adaptive process provoked by chronic administration of selective serotonin reuptake inhibitors (SSRIs) and atypical antipsychotics. Suicidal and otherwise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
