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Radioligand
A radioligand is a microscopic particle which consists of a Radiopharmaceutical, therapeutic radioactive isotope and the cell-targeting compound - the ligand. The ligand is the target binding site, it may be on the surface of the targeted cancer cell for therapeutic purposes. Radioisotopes can occur naturally or be synthesized and produced in a cyclotron/nuclear reactor. The different types of radioisotopes include Y-90, H-3, C-11, Lu-177, Ac-225, Ra-223, In-111, I-131, I-125, etc. Thus, radioligands must be produced in special nuclear reactors for the radioisotope to remain stable. Radioligands can be used to analyze/characterize receptors, to perform binding assays, to help in diagnostic imaging, and to provide targeted cancer therapy. Radiation is a novel method of treating cancer and is effective in short distances along with being unique/personalizable and causing minimal harm to normal surrounding cells. Furthermore, radioligand binding can provide information about receptor-l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Positron Emission Tomography
Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. Different tracers are used for various imaging purposes, depending on the target process within the body, such as: * Fluorodeoxyglucose ( 18F">sup>18FDG or FDG) is commonly used to detect cancer; * 18Fodium fluoride">sup>18Fodium fluoride (Na18F) is widely used for detecting bone formation; * Oxygen-15 (15O) is sometimes used to measure blood flow. PET is a common imaging technique, a medical scintillography technique used in nuclear medicine. A radiopharmaceutical—a radioisotope attached to a drug—is injected into the body as a tracer. When the radiopharmaceutical undergoes beta plus decay, a positron is emitted, and when the positron interacts with an ordinary electron, the tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon-11
Carbon (6C) has 14 known isotopes, from to as well as , of which only and are stable nuclide, stable. The longest-lived radionuclide, radioisotope is , with a half-life of years. This is also the only carbon radioisotope found in nature, as trace quantities are formed cosmogenic nuclide, cosmogenically by the reaction + → + . The most stable artificial radioisotope is , which has a half-life of . All other radioisotopes have half-lives under 20 seconds, most less than 200 milliseconds. The least stable isotope is , with a half-life of . Light isotopes tend to decay into isotopes of boron and heavy ones tend to decay into isotopes of nitrogen. List of isotopes , -id=Carbon-8 , , style="text-align:right" , 6 , style="text-align:right" , 2 , , [] , proton emission, 2p , Also immediately emits two protons for the net reaction of → + 4 , 0+ , , , -id=Carbon-9 , rowspan=3, , rowspan=3 style="text-align:right" , 6 , rowspan=3 style="text-align ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuroendocrine Tumor
Neuroendocrine tumors (NETs) are neoplasms that arise from cells of the endocrine (hormonal) and nervous systems. They most commonly occur in the intestine, where they are often called carcinoid tumors, but they are also found in the pancreas, lung, and the rest of the body. Although there are many kinds of NETs, they are treated as a group of tissue because the cells of these neoplasms share common features, including a similar histological appearance, having special secretory granules, and often producing biogenic amines and polypeptide hormones. The term "neuro" refers to the dense core granules (DCGs), similar to the DCGs in the serotonergic neurons storing monoamines. The term "endocrine" refers to the synthesis and secretion of these monoamines. The neuroendocrine system includes endocrine glands such as the pituitary, the parathyroids and the neuroendocrine adrenals, as well as endocrine islet tissue embedded within glandular tissue such as in the pancreas, and scatt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorine-18
Fluorine-18 (18F, also called radiofluorine) is a fluorine radioisotope which is an important source of positrons. It has a mass of 18.0009380(6) u and its half-life is 109.771(20) minutes. It decays by positron emission 96.7% of the time and electron capture 3.3% of the time. Both modes of decay yield stable oxygen-18. Natural occurrence is a natural trace radioisotope produced by cosmic ray spallation of atmospheric argon as well as by reaction of protons with natural oxygen: 18O + p → 18F + n.sup>18Oater with high energy protons (typically ~18 MeV). The fluorine produced is in the form of a water solution of 18F">sup>18F luoride, which is then used in a rapid chemical synthesis of various radio pharmaceuticals. The organic oxygen-18 pharmaceutical molecule is not made before the production of the radiopharmaceutical, as high energy protons destroy such molecules ( radiolysis). Radiopharmaceuticals using fluorine must therefore be synthesized after the fluorine-18 has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme-linked Receptor
An enzyme-linked receptor, also known as a catalytic receptor, is a transmembrane receptor, where the binding of an extracellular ligand causes enzymatic activity on the intracellular side. Hence a catalytic receptor is an integral membrane protein possessing both catalytic, and receptor functions. They have two important domains, an extra-cellular ligand binding domain and an intracellular domain, which has a catalytic function; and a single transmembrane helix. The signaling molecule binds to the receptor on the outside of the cell and causes a conformational change on the catalytic function located on the receptor inside the cell. Examples of the enzymatic activity include: * Receptor tyrosine kinase, as in fibroblast growth factor receptor. Most enzyme-linked receptors are of this type. * Serine/threonine-specific protein kinase A serine/threonine protein kinase () is a kinase enzyme, in particular a protein kinase, that phosphorylation, phosphorylates the hydrox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
G Protein-coupled Receptor
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors, 7TM receptors, heptahelical receptors, serpentine receptors, and G protein-linked receptors (GPLR), form a large group of evolutionarily related proteins that are cell surface receptors that detect molecules outside the cell and activate cellular responses. They are coupled with G proteins. They pass through the cell membrane seven times in the form of six loops (three extracellular loops interacting with ligand molecules, three intracellular loops interacting with G proteins, an N-terminal extracellular region and a C-terminal intracellular region) of amino acid residues, which is why they are sometimes referred to as seven-transmembrane receptors. Text was copied from this source, which is available under Attribution 2.5 Generic (CC BY 2.5) licence/ref> Ligands can bind either to the extracellular N-terminus and loops (e.g. glutamate receptors) or to the binding site wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Channel Receptor
Ligand-gated ion channels (LICs, LGIC), also commonly referred to as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as Na+, K+, Ca2+, and/or Cl− to pass through the membrane in response to the binding of a chemical messenger (i.e. a ligand), such as a neurotransmitter. When a presynaptic neuron is excited, it releases a neurotransmitter from vesicles into the synaptic cleft. The neurotransmitter then binds to receptors located on the postsynaptic neuron. If these receptors are ligand-gated ion channels, a resulting conformational change opens the ion channels, which leads to a flow of ions across the cell membrane. This, in turn, results in either a depolarization, for an excitatory receptor response, or a hyperpolarization, for an inhibitory response. These receptor proteins are typically composed of at least two different domains: a transmembrane domain which includes the ion pore, and an extracellular domain w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Surface Receptor
Cell surface receptors (membrane receptors, transmembrane receptors) are receptors that are embedded in the plasma membrane of cells. They act in cell signaling by receiving (binding to) extracellular molecules. They are specialized integral membrane proteins that allow communication between the cell and the extracellular space. The extracellular molecules may be hormones, neurotransmitters, cytokines, growth factors, cell adhesion molecules, or nutrients; they react with the receptor to induce changes in the metabolism and activity of a cell. In the process of signal transduction, ligand binding affects a cascading chemical change through the cell membrane. Structure and mechanism Many membrane receptors are transmembrane proteins. There are various kinds, including glycoproteins and lipoproteins. Hundreds of different receptors are known and many more have yet to be studied. Transmembrane receptors are typically classified based on their tertiary (three-dimens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
202304 G Protein-coupled Receptor
3 (three) is a number, numeral and digit. It is the natural number following 2 and preceding 4, and is the smallest odd prime number and the only prime preceding a square number. It has religious and cultural significance in many societies. Evolution of the Arabic digit The use of three lines to denote the number 3 occurred in many writing systems, including some (like Roman and Chinese numerals) that are still in use. That was also the original representation of 3 in the Brahmic (Indian) numerical notation, its earliest forms aligned vertically. However, during the Gupta Empire the sign was modified by the addition of a curve on each line. The Nāgarī script rotated the lines clockwise, so they appeared horizontally, and ended each line with a short downward stroke on the right. In cursive script, the three strokes were eventually connected to form a glyph resembling a with an additional stroke at the bottom: ३. The Indian digits spread to the Caliphate in the 9th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radium-223
Radium-223 (223Ra, Ra-223) is an Isotopes of radium#Radium-223, isotope of radium with an 11.4-day half-life. It was discovered in 1905 by T. Godlewski, a Polish chemist from Kraków, and was historically known as Decay chain#Actinium series, actinium X (AcX). Radium-223 dichloride is an alpha particle-emitting radiotherapy drug that mimics calcium and forms complexes with hydroxyapatite at areas of increased bone turnover. The principal use of radium-223, as a radiopharmaceutical to treat Metastasis, metastatic cancers in bone, takes advantage of its chemical similarity to calcium, and the short range of the alpha radiation it emits. Origin and preparation Although radium-223 is naturally formed in trace amounts by the Decay chain#Actinium series, decay of uranium-235, it is generally made artificially,Bruland O.S., Larsen R.H. (2003). Radium revisited. In: Bruland O.S., Flgstad T., editors. Targeted cancer therapies: An odyssey. University Library of Tromso, Ravnetrykk No. 29. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lutetium-177
Naturally occurring lutetium (71Lu) is composed of one stable isotope 175Lu (97.41% natural abundance) and one long-lived radioisotope, 176Lu with a half-life of 37 billion years (2.59% natural abundance). Forty radioisotopes have been characterized, with the most stable, besides 176Lu, being 174Lu with a half-life of 3.31 years, and 173Lu with a half-life of 1.37 years. All of the remaining Radioactive decay, radioactive isotopes have half-lives that are less than 9 days, and the majority of these have half-lives that are less than half an hour. This element also has 18 meta states, with the most stable being 177mLu (t1/2 160.4 days), 174mLu (t1/2 142 days) and 178mLu (t1/2 23.1 minutes). The known isotopes of lutetium range in mass number from 149 to 190. The primary decay mode before the most abundant stable isotope, 175Lu, is electron capture (with some alpha emission, alpha and positron emission), and the primary mode after is beta emission. The primary decay products before 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strontium-89
Strontium-89 () is a radioactive isotope of strontium produced by nuclear fission, with a half-life of 50.57 days. It undergoes beta decay, β− decay into yttrium-89. Strontium-89 has an application in medicine. History Strontium-89 was first synthesized in 1937 by D. W. Stewart et al. at the University of Michigan; it was synthesized via irradiation of stable strontium (88Sr) with deuterons. Biological properties and applications of strontium-89 were studied for the first time by Belgian scientist Charles Pecher. Pecher filed a patent in May 1941 for the synthesis of strontium-89 and yttrium-86 using cyclotrons, and described the therapeutic use of strontium. Physiological effects and medical use Strontium belongs to the same periodic family as calcium (alkaline earth metals), and is metabolised in a similar fashion, preferentially targeting metabolically active regions of the bone. 89Sr is an artificial radioisotope used in the treatment of osseous (bony) metastases of b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
