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Leukotrienes
Leukotrienes are a family of eicosanoid inflammation, inflammatory mediators produced in leukocytes by the redox, oxidation of arachidonic acid (AA) and the essential fatty acid eicosapentaenoic acid (EPA) by the enzyme arachidonate 5-lipoxygenase. Leukotrienes use lipid signaling to convey information to either the cell producing them (autocrine signaling) or neighboring cells (paracrine signaling) in order to regulate immune responses. The production of leukotrienes is usually accompanied by the production of histamine and prostaglandins, which also act as inflammatory mediators. One of their roles (specifically, Leukotriene D4, leukotriene D4) is to trigger contractions in the smooth muscles lining the bronchioles; their overproduction is a major cause of inflammation in asthma and allergic rhinitis. Leukotriene antagonists are used to treat these disorders by inhibiting the production or activity of leukotrienes. History and name The name ''leukotriene'', introduced by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eicosanoid
Eicosanoids are lipid signaling, signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, around 20 carbon units in length. Eicosanoids are a sub-category of oxylipins, i.e. oxidized fatty acids of diverse carbon units in length, and are distinguished from other oxylipins by their overwhelming importance as cell signaling molecules. Eicosanoids function in diverse physiological systems and pathological processes such as: mounting or inhibiting inflammation, allergy, fever and other immune responses; regulating the abortion of pregnancy and normal childbirth; contributing to the perception of pain; regulating cell growth; controlling blood pressure; and modulating the regional flow of blood to tissues. In performing these roles, eicosanoids most often act as autocrine signaling agents to impact their cells of origin or as paracrine signaling agents to impact cells in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene C4
Leukotriene C4 (LTC4) is a leukotriene. LTC4 has been extensively studied in the context of allergy and asthma. In cells of myeloid origin such as mast cells, its biosynthesis is orchestrated by translocation to the nuclear envelope along with co-localization of PLA2G4A, cytosolic phospholipase A2 (cPLA2), 5-lipoxygenase, arachidonate 5-lipoxygenase (5-LO), 5-lipoxygenase-activating protein (FLAP) and Leukotriene C4 synthase, LTC4 synthase (LTC4S), which couples glutathione to an Leukotriene A4, LTA4 intermediate. The ABCC1, MRP1 transporter then secretes cytosolic LTC4 and cell surface proteases further metabolize it by sequential cleavage of the γ-glutamyl and glycine residues off its glutathione segment, generating the more stable products Leukotriene D4, LTD4 and Leukotriene E4, LTE4. All three leukotrienes then bind at different affinities to two G-protein coupled receptors: CYSLTR1 and CYSLTR2, triggering pulmonary vasoconstriction and bronchoconstriction. In cells of non-h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene A4
Leukotriene A4 (LTA4) is a leukotriene Leukotrienes are a family of eicosanoid inflammation, inflammatory mediators produced in leukocytes by the redox, oxidation of arachidonic acid (AA) and the essential fatty acid eicosapentaenoic acid (EPA) by the enzyme arachidonate 5-lipoxyg ..., and is the precursor for the productions of leukotriene B4 (LTB4) and leukotriene C4 (LTC4). Biosynthesis Following the biosynthesis of eicosanoid, triggered as a result of infection or inflammation, the resulting arachidonic acid substrate is released from the cell membrane phospholipid will enter the lipooxygenase pathway to produce leukotriene A4. In this pathway, arachidonic acid is converted into 5-hydroperoxyeicosatetraenoic acid (5-HPETE) as a result of a catalytic complex consisting of the enzyme 5-lipoxygenase (5-LO) and 5-lipoxygenase-activating protein (FLAP) in the presence of ATP and calcium ions. The resulting 5-HPETE yields the unstable allylic epoxide substrate LTA4 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene D4
Leukotriene D4 (LTD4) is one of the leukotrienes. Its main function in the body is to induce the contraction of smooth muscle, resulting in bronchoconstriction and vasoconstriction. It also increases vascular permeability. LTD4 is released by basophils. Other leukotrienes that function in a similar manner are leukotrienes C4 and E4. Pharmacological agents that inhibit the function of these leukotrienes are leukotriene receptor antagonists (e.g., zafirlukast, montelukast) and are useful for asthmatic individuals. References Eicosanoids {{biochemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene E4
Leukotriene E4 (LTE4) is a cysteinyl leukotriene involved in inflammation. It is known to be produced by several types of white blood cells, including eosinophils, mast cells, tissue macrophages, and basophils, and recently was also found to be produced by platelets adhering to neutrophils. It is formed from the sequential conversion of LTC4 to LTD4 and then to LTE4, which is the final and most stable cysteinyl leukotriene. Compared to the short half lives of LTC4 and LTD4, LTE4 is relatively stable and accumulates in breath condensation, in plasma, and in urine, making it the dominant cysteinyl leukotriene detected in biologic fluids. Therefore, measurements of LTE4, especially in the urine, are commonly monitored in clinical research studies. Increased production and excretion of LTE4 has been linked to several respiratory diseases, and urinary LTE4 levels are increased during severe asthma attacks and are especially high in people with aspirin-exacerbated respiratory disea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene D4
Leukotriene D4 (LTD4) is one of the leukotrienes. Its main function in the body is to induce the contraction of smooth muscle, resulting in bronchoconstriction and vasoconstriction. It also increases vascular permeability. LTD4 is released by basophils. Other leukotrienes that function in a similar manner are leukotrienes C4 and E4. Pharmacological agents that inhibit the function of these leukotrienes are leukotriene receptor antagonists (e.g., zafirlukast, montelukast) and are useful for asthmatic individuals. References Eicosanoids {{biochemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene B4
Leukotriene B4 (LTB4) is a leukotriene involved in inflammation. It has been shown to promote insulin resistance in obese mice. Biochemistry LTB4 is a leukotriene involved in inflammation. It is produced from leukocytes in response to inflammatory mediators and is able to induce the adhesion and activation of leukocytes on the endothelium, allowing them to bind to and cross it into the tissue. In neutrophils, it is also a potent chemoattractant, and is able to induce the formation of reactive oxygen species and the release of Lysosome, lysosomal enzymes by these cells. It is synthesized by leukotriene-A4 hydrolase from Leukotriene A4, leukotriene A4. Diabetes A study at the University of California, San Diego School of Medicine has shown that LTB4 promotes insulin resistance in obese mice. Obesity is the major cause of insulin resistance in type 2 diabetes. References {{PPAR modulators Eicosanoids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slow-reacting Substance Of Anaphylaxis
The slow-reacting substance of anaphylaxis or SRS-A is a mixture of the leukotrienes LTC4, LTD4 and LTE4. Mast cells secrete it during the anaphylactic reaction, inducing inflammation. It can be found in basophils. It induces prolonged, slow contraction of smooth muscle and has a major bronchoconstrictor role in asthma. Compared to histamine Histamine is an organic nitrogenous compound involved in local immune responses communication, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Discovered in 19 ..., it is approximately 1000 times more potent and has a slower onset but longer duration of action. References External links * Allergology {{Biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bengt Samuelsson
Bengt Ingemar Samuelsson (21 May 1934 – 5 July 2024) was a Swedish biochemist. He shared with Sune K. Bergström and John R. Vane the 1982 Nobel Prize for Physiology or Medicine for discoveries concerning prostaglandins and related substances. Education and early life Samuelsson was born in Halmstad in southwest Sweden, studied at Lund University, and was a professor in medical and physiological chemistry at Karolinska Institute in Stockholm in 1973. He was president of Karolinska Institute from 1982 to 1995 and chairman of the Nobel Foundation from 1993 to 2005. Research and career Discussing the role of prostaglandins in the body, Samuelsson explained, "It's a control system for the cells that participates in many biological functions. There are endless possibilities of manipulating this system in drug development." His research interests were originally in cholesterol metabolism with importance to reaction mechanisms. Following the structural work on prostaglandins al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene Antagonist
An antileukotriene, also known as leukotriene modifier and leukotriene receptor antagonist, is a medication which functions as a leukotriene-related enzyme inhibitor (arachidonate 5-lipoxygenase) or leukotriene receptor antagonist ( cysteinyl leukotriene receptors) and consequently opposes the function of these inflammatory mediators; leukotrienes are produced by the immune system and serve to promote bronchoconstriction, inflammation, microvascular permeability, and mucus secretion in asthma and COPD. Leukotriene receptor antagonists are sometimes colloquially referred to as ''leukasts''. Leukotriene receptor antagonists, such as montelukast, zafirlukast, and pranlukast, and 5-lipoxygenase inhibitors, like zileuton and ''Hypericum perforatum'', can be used to treat these diseases. They are less effective than corticosteroids for treating asthma, but more effective for treating certain mast cell disorders. Approaches There are two main approaches to block the actions of leukotr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
