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Dicumarol
Dicoumarol (INN) or dicumarol (USAN) is a naturally occurring anticoagulant drug that depletes stores of vitamin K (similar to warfarin, a drug that dicoumarol inspired). It is also used in biochemical experiments as an inhibitor of reductases. Dicoumarol is a natural chemical substance of combined plant and fungal origin. It is a derivative of coumarin, a bitter-tasting but sweet-smelling substance made by plants that does not itself affect coagulation, but which is (classically) transformed in mouldy feeds or silages by a number of species of fungi, into active dicoumarol. Dicoumarol does affect coagulation, and was discovered in mouldy wet sweet-clover hay, as the cause of a naturally occurring bleeding disease in cattle. See warfarin for a more detailed discovery history. Identified in 1940, dicoumarol became the prototype of the 4-hydroxycoumarin anticoagulant drug class. Dicoumarol itself, for a short time, was employed as a medicinal anticoagulant drug, but since the mid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-Hydroxycoumarins
4-Hydroxycoumarins belong to a class of vitamin K antagonist (VKA) anticoagulant drug molecules derived from coumarin by adding a hydroxy group at the 4 position to obtain 4-hydroxycoumarin, then adding a large aromatic substituent at the 3-position (the ring-carbon between the hydroxyl and the carbonyl). The large 3-position substituent is required for anticoagulant activity. The primary mechanism of the 4-hydroxycoumarin drugs is the inhibition of vitamin K epoxide reductase. These compounds are not direct antagonists (in the pharmaceutical sense) of vitamin K, but rather act to deplete reduced vitamin K in tissues. For this reason vitamin K antagonizes their effect, and this has led to the loose terminology of vitamin K antagonism. Origin Although 4-hydroxycoumarin itself is not an anticoagulant, it is an important fungal metabolite from the precursor coumarin, which is also not an anticoagulant, and its production leads to further fermentative production of the natural antic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin K Antagonists
Vitamin K antagonists (VKA) are a group of substances that reduce blood clotting by reducing the action of vitamin K. The term "vitamin K antagonist" is technically a misnomer, as the drugs do not directly antagonise the action of vitamin K in the pharmacological sense, but rather the recycling of vitamin K. They are used as anticoagulant medications in the prevention of thrombosis, and in pest control, as rodenticides. Mechanism of action These drugs deplete the active form of the vitamin by inhibiting the enzyme vitamin K epoxide reductase and thus the recycling of the inactive vitamin K epoxide back to the active reduced form of vitamin K. The drugs are structurally similar to vitamin K and act as competitive inhibitors of the enzyme. The term "vitamin K antagonist" is a misnomer, as the drugs do not directly receptor antagonist, antagonise the action of vitamin K in the pharmacological sense, but rather the recycling of vitamin K. Vitamin K is required for the proper pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karl Paul Link
Karl Paul Gerhard Link (31 January 1901 – 21 November 1978) was an American biochemist best known for his discovery of the anticoagulant warfarin. Training and early career He was born in LaPorte, Indiana to a Lutheran minister of German descent as one of ten children. He was schooled locally, and attended the University of Wisconsin–Madison, where he studied agricultural chemistry at the College of Agriculture from 1918 to 1925, obtaining an MS in 1923 and a PhD in 1925. He was then chosen by the national Education Board for a postdoctoral scholarship, and relocated to Europe. He briefly worked with carbohydrate chemist Sir James Irvine at the University of St Andrews in Scotland and from 1926 in Graz, Austria with Fritz Pregl, inventor of microchemistry and Nobel Laureate. Finally he spent several months with organic chemist and future Nobel laureate Paul Karrer in the latter's lab in Zurich; during this period Link suffered from tuberculosis, requiring recuperation in Davo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prothrombin Time
The prothrombin time (PT) – along with its derived measures of prothrombin ratio (PR) and international normalized ratio (INR) – is an assay for evaluating the ''extrinsic'' pathway and common pathway of coagulation. This blood test is also called ''protime INR'' and ''PT/INR''. They are used to determine the clotting tendency of blood, in such things as the measure of warfarin dosage, liver damage, and vitamin K status. PT measures the following coagulation factors: I (fibrinogen), II (prothrombin), V (proaccelerin), VII (proconvertin), and X (Stuart–Prower factor). PT is often used in conjunction with the activated partial thromboplastin time (aPTT) which measures the ''intrinsic'' pathway and common pathway of coagulation. Laboratory measurement The reference range for prothrombin time depends on the analytical method used, but is usually around 12–13 seconds (results should always be interpreted using the reference range from the laboratory that performed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coumarin Drugs
Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered heterocycle that shares two carbons with the benzene ring. It can be placed in the benzopyrone chemical class and considered as a lactone. Coumarin is a colorless crystalline solid with a sweet odor resembling the scent of vanilla and a bitter taste. It is found in many plants, where it may serve as a chemical defense against predators. By inhibiting synthesis of vitamin K, a related compound is used as the prescription drug warfarin – an anticoagulant – to inhibit formation of blood clots, deep vein thrombosis, and pulmonary embolism. Etymology Coumarin is derived from ''coumarou'', the French word for the tonka bean. The word ''tonka'' for the tonka bean is taken from the Galibi (Carib) tongue spoken by natives of French Guia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethyl Biscoumacetate
Ethyl biscoumacetate is a vitamin K Vitamin K refers to structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. The human body requires vitamin K for post-synthesis modification of certain proteins that are required for blood coagulation ... antagonist. References * The Merck Index, 12th Edition. 3818 Coumarin drugs Ethyl esters {{blood-drug-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Great Depression
The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagion began around September and led to the Wall Street stock market crash of October 24 (Black Thursday). It was the longest, deepest, and most widespread depression of the 20th century. Between 1929 and 1932, worldwide gross domestic product (GDP) fell by an estimated 15%. By comparison, worldwide GDP fell by less than 1% from 2008 to 2009 during the Great Recession. Some economies started to recover by the mid-1930s. However, in many countries, the negative effects of the Great Depression lasted until the beginning of World War II. Devastating effects were seen in both rich and poor countries with falling personal income, prices, tax revenues, and profits. International trade fell by more than 50%, unemployment in the U.S. rose to 23% an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agricultural Extension
Agricultural extension is the application of scientific research and new knowledge to agricultural practices through farmer education. The field of 'extension' now encompasses a wider range of communication and learning activities organized for rural people by educators from different disciplines, including agriculture, agricultural marketing, health, and business studies. Extension practitioners can be found throughout the world, usually working for government agencies. They are represented by several professional organizations, networks and extension journals. Agricultural extension agencies in developing countries receive large amounts of support from international development organizations such as the World Bank and the Food and Agriculture Organization of the United Nations. Extension terminology The use of the word 'extension' originated in england in 1866.Modern extension began in Dublin, Ireland in 1847 with Lord Clarendon's itinerant instructors during the great fami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemorrhage
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vagina or anus, or through a puncture in the skin. Hypovolemia is a massive decrease in blood volume, and death by excessive loss of blood is referred to as exsanguination. Typically, a healthy person can endure a loss of 10–15% of the total blood volume without serious medical difficulties (by comparison, blood donation typically takes 8–10% of the donor's blood volume). The stopping or controlling of bleeding is called hemostasis and is an important part of both first aid and surgery. Types * Upper head ** Intracranial hemorrhage – bleeding in the skull. ** Cerebral hemorrhage – a type of intracranial hemorrhage, bleeding within the brain tissue itself. ** Intracerebral hemorrhage – bleeding in the brain caused by the ruptu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overdose
A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended.Definitions Retrieved on 20 September 2014."Stairway to Recovery: Glossary of Terms" . Retrieved on 19 March 2021 Typically it is used for cases when a risk to health will potentially result. An overdose may result in a toxic state or . Classification [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prothrombin
Thrombin (, ''fibrinogenase'', ''thrombase'', ''thrombofort'', ''topical'', ''thrombin-C'', ''tropostasin'', ''activated blood-coagulation factor II'', ''blood-coagulation factor IIa'', ''factor IIa'', ''E thrombin'', ''beta-thrombin'', ''gamma-thrombin'') is a serine protease, an enzyme that, in humans, is encoded by the ''F2'' gene. Prothrombin (coagulation factor II) is proteolytically cleaved to form thrombin in the clotting process. Thrombin in turn acts as a serine protease that converts soluble fibrinogen into insoluble strands of fibrin, as well as catalyzing many other coagulation-related reactions. History After the description of fibrinogen and fibrin, Alexander Schmidt hypothesised the existence of an enzyme that converts fibrinogen into fibrin in 1872. Prothrombin was discovered by Pekelharing in 1894. Physiology Synthesis Thrombin is produced by the enzymatic cleavage of two sites on prothrombin by activated Factor X (Xa). The activity of factor Xa is greatl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
