High Quality Content by WIKIPEDIA articles! Aminopterin (4-aminopteroic acid), a 4-amino analog of folic acid, is an antineoplastic drug with immunosuppressive properties used in chemotherapy. Aminopterin is a synthetic derivative of pterin. Aminopterin works as an enzyme inhibitor by competing for the folate binding site of the enzyme dihydrofolate reductase. Its binding affinity for dihydrofolate reductase effectively blocks tetrahydrofolate synthesis. This results in the depletion of nucleotide precursors and inhibition of DNA, RNA, and protein synthesis.
High Quality Content by WIKIPEDIA articles! Amlodipine (as besylate, mesylate or maleate) is a long-acting calcium channel blocker (dihydropyridine (DHP) class) used as an anti-hypertensive and in the treatment of angina. Like other calcium channel blockers, amlodipine acts by relaxing the smooth muscle in the arterial wall, decreasing total peripheral resistance and hence reducing blood pressure; in angina it increases blood flow to the heart muscle (although DHP-class calcium channel blockers are more selective for arteries than myocardium, as the cardiac calcium channels are not of the dihydropyridine-type).
High Quality Content by WIKIPEDIA articles! Amobarbital (formerly known as amylobarbitone) is a drug that is a barbiturate derivative. It has sedative-hypnotic and analgesic properties. It is a white crystalline powder with no odor and a slightly bitter taste. It was first synthesized in Germany in 1923. If amobarbital is taken for extended periods of time, physical and psychological dependence can develop.
High Quality Content by WIKIPEDIA articles! Amoxapine (Amokisan, Asendin, Asendis, Defanyl, Demolox, Moxadil) is a tetracyclic antidepressant of the dibenzoxazepine family, though it is often classified as a secondary amine tricyclic antidepressant.
High Quality Content by WIKIPEDIA articles! Anandamide, also known as N-arachidonoylethanolamide or AEA, is an endogenous cannabinoid neurotransmitter. The name is taken from the Sanskrit word ananda, which means "bliss, delight", and amide. It is synthesized from N-arachidonoyl phosphatidylethanolamine by multiple pathways. It is degraded primarily by the fatty acid amide hydrolase (FAAH) enzyme, which converts anandamide into ethanolamine and arachidonic acid. As such, inhibitors of FAAH lead to elevated anandamide levels and are being pursued for therapeutic use.
High Quality Content by WIKIPEDIA articles! Oceanic anoxic events or anoxic events occur when the Earth`s oceans become completely depleted of oxygen (O2) below the surface levels. Although anoxic events have not happened for millions of years, the geological record shows that they happened many times in the past. Anoxic events may have caused mass extinctions. These mass extinctions were so characteristic, they include some that geobiologists use as time markers in biostratigraphic dating. It is believed oceanic anoxic events are strongly linked to lapses in key oceanic current circulations, to climate warming and greenhouse gases.
High Quality Content by WIKIPEDIA articles! Anthraquinone, also called anthracenedione or dioxoanthracene is an aromatic organic compound with formula C14H8O2. Several isomers are possible, each of which can be viewed as a quinone derivative. The term anthraquinone, however, almost invariably refers to one specific isomer, 9,10-anthraquinone (IUPAC: 9,10-dioxoanthracene) wherein the keto groups are located on the central ring. It is a building block of many dyes and is used in bleaching pulp for papermaking. It is a yellow highly crystalline solid, poorly soluble in water but soluble in hot organic solvents. For instance, it is almost completely insoluble in ethanol near room temperature but 2.25 g will dissolve in 100 g of boiling ethanol.
High Quality Content by WIKIPEDIA articles! In particle physics, antimatter is material composed of antiparticles, which have the same mass as particles of ordinary matter but have opposite charge and quantum spin. Antiparticles bind with each other to form antimatter in the same way that normal particles bind to form normal matter. For example, a positron (the antiparticle of the electron, with symbol e+) and an antiproton (symbol p) can form an antihydrogen atom. Furthermore, mixing matter and antimatter can lead to the annihilation of both, in the same way that mixing antiparticles and particles does, thus giving rise to high-energy photons (gamma rays) or other particle–antiparticle pairs. The end result of antimatter meeting...
High Quality Content by WIKIPEDIA articles! Copper and its alloys (brasses, bronzes, cupronickel, copper-nickel-zinc, and others) are natural antimicrobial materials. Ancient civilizations exploited the antimicrobial properties of copper long before the concept of microbes became understood in the nineteenth century. In addition to several copper medicinal preparations, it was also observed centuries ago that water contained in copper vessels or transported in copper conveyance systems was of better quality (i.e., no or little visible slime formation) than water contained or transported in other materials.
High Quality Content by WIKIPEDIA articles! Antimony potassium tartrate, also known as potassium antimonyl tartrate or emetic tartar has the formula K2Sb2(C4H2O6)2 is the double salt of potassium and antimony of tartaric acid. The compound has long been known as a powerful emetic. Besides, the compound was used in the treatment of schistosomiasis and leishmaniasis.
High Quality Content by WIKIPEDIA articles! Antimony (Latin: stibium) is a chemical element with symbol Sb and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient times and were used for cosmetics; metallic antimony was also known, but it was erroneously identified as lead. It was established to be an element around the 17th century.
High Quality Content by WIKIPEDIA articles! Antimicrobial copper alloy touch surfaces are surfaces that are made from alloys of the metal copper, such as brass and bronze. The phrase "touch surfaces" means all the various kinds of surfaces (such as door knobs, railings, tray tables, etc.) that are often touched by people at work or in everyday life, especially (for example) in hospitals and clinics.
High Quality Content by WIKIPEDIA articles! Antimatter comets (and antimatter meteorites) are theoretical comets (meteorites) composed solely of antimatter instead of ordinary matter. Although never actually observed, and unlikely to exist anywhere within the Milky Way, they have been hypothesized to exist, and their existence, on the presumption that hypothesis is correct, has been put forward as one possible explanations for different observed natural phenomena over the years.
High Quality Content by WIKIPEDIA articles! High-precision experiments could reveal small previously unseen differences between the behavior of matter and antimatter. This prospect is appealing to physicists because it may show that nature is not Lorentz symmetric.
High Quality Content by WIKIPEDIA articles! The Antiproton Decelerator (AD) is a storage ring at the CERN laboratory in Geneva. It was built as a successor to the Low Energy Antiproton Ring (LEAR) and started operation in the year 2000. The decelerated antiprotons are ejected to one of several connected experiments.
High Quality Content by WIKIPEDIA articles! Apaziquone (EOquin) is an indolequinone that is a bioreductive prodrug and a chemical analog of the older chemotherapeutic agent mitomycin C. In hypoxic cells, such as those on the inner surface of the urinary bladder, apaziquone is converted to active metabolites by intracellular reductases. The active metabolites alkylate DNA and lead to apoptotic cell death. This activity is preferentially expressed in neoplastic cells.
High Quality Content by WIKIPEDIA articles! Apixaban (INN, trade name Eliquis) is an anticoagulant for the prevention of venous thromboembolism and venous thromboembolic events. It is a direct factor Xa inhibitor. Apixaban has been available in Europe since May 2012 and was approved for preventing venous thromboembolism after elective hip or knee replacement. The FDA approved apixaban in December 2012 with an indication of reducing the risk of stroke and dangerous blood clots (systemic embolism) in patients with atrial fibrillation that is not caused by a heart valve problem. The drug was developed in a joint venture by Pfizer and Bristol-Myers Squibb.
High Quality Content by WIKIPEDIA articles! Aprepitant (Emend (US, EU)) is an antiemetic chemical compound that belongs to a class of drugs called substance P antagonists (SPA). It mediates its effect by blocking the neurokinin 1 (NK1) receptor.
High Quality Content by WIKIPEDIA articles! Aqua regia (lit. "royal water"), aqua regis (lit. "king`s water"), or nitro-hydrochloric acid is a highly corrosive mixture of acids, a fuming yellow or red solution. The mixture is formed by freshly mixing concentrated nitric acid and hydrochloric acid, usually in a volume ratio of 1:3. It was named so because it can dissolve the so-called royal or noble metals, gold and platinum. However, titanium, iridium, ruthenium, tantalum, osmium, rhodium and a few other metals are capable of withstanding its corrosive properties.