| argentic | <chemistry> Pertaining to, derived from, or containing, silver; said of certain compounds of silver in which this metal has its lowest proportion; as, argentic chloride. Source: Websters Dictionary (01 Mar 1998) |
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| argentine | 1. <chemical> A siliceous variety of calcite, or carbonate of lime, having a silvery-white, pearly luster, and a waving or curved lamellar structure. 2. White metal coated with silver. 3. <zoology> A fish of Europe (Maurolicus Pennantii) with silvery scales. The name is also applied to various fishes of the genus Argentina. 4. A citizen of the Argentine Republic. Origin: Cf. F. Argentin, fr. L. Argentum silver. Source: Websters Dictionary (01 Mar 1998) |
| Argentine haemorrhagic fever virus | A member of the Arenaviridae. (05 Mar 2000) |
| Argentinean haemorrhagic fever | A form of haemorrhagic fever observed in South America, seemingly transmitted by contact from rodents to man and caused by the Junin virus, a member of the family Arenaviridae. (05 Mar 2000) |
| argentite | <chemical> Sulphide of silver; also called vitreous silver, or silver glance. It has a metallic luster, a lead-gray colour, and is sectile like lead. Origin: L. Argentum silver. Source: Websters Dictionary (01 Mar 1998) |
| argentophil | <pathology> Pertaining to tissue elements that are capable of impregnation with silver ions and being made visible after an external reducing agent is used. Synonym: argentophil, argentophile. Origin: G. Argyros, silver, + philos, fond (05 Mar 2000) |
| argentous | <chemistry> Of, pertaining to, or containing, silver; said of certain silver compounds in which silver has a higher proportion than in argentic compounds; as, argentous chloride. Source: Websters Dictionary (01 Mar 1998) |
| argentry | Silver plate or vessels. Origin: F. Argenterie, fr. Argent silver, L. Argentum. Source: Websters Dictionary (01 Mar 1998) |
| argentum | Synonym: silver. Origin: L. (05 Mar 2000) |
| argil | <chemical> Clay, or potter's earth; sometimes pure clay, or alumina. See Clay. Origin: F. Argile, L. Argilla white clay, akin to Gr. Or argil, white. See Argent. Source: Websters Dictionary (01 Mar 1998) |
| argillaceous | Of the nature of clay; consisting of, or containing, argil or clay; clayey. <geology> Argillaceous sandstone, a sandstone containing much clay. Argillaceous iron ore, the clay ironstone. Argillaceous schist or state. See Argillite. Origin: L. Argillaceus, fr. Argilla. Source: Websters Dictionary (01 Mar 1998) |
| argillite | <chemical> Argillaceous schist or slate; clay slate. Its colours is bluish or blackish gray, sometimes greenish gray, brownish red, etc. Argillit"ic. Origin: Gr. Clay. Source: Websters Dictionary (01 Mar 1998) |
| arginase | <enzyme> A ureahydrolase that catalyses the hydrolysis of arginine and canavanine to yield l-ornithine and urea. Chemical name: L-Arginine amidinohydrolase Registry number: EC 3.5.3.1 (12 Dec 1998) |
| arginase deficiency | <biochemistry> Arginase is the fifth enzyme of the urea cycle and catalyses the hydrolysis of arginine to ornithine and urea as the final step in the detoxification of ammonia. Deficiency of the enzyme results in hyperargininaemia and episodic hyperammonaemia, leading to moderate to severe mental retardation and spasticity. at least two isozymes of arginase exist in man. AI (the enzyme deficient in the disorder) is cytosolic and found primarily in liver and red blood cells, whereas AII is mitochondrial and found predominantly in kidney but also to a lesser extent in liver, brain, and other tissues. While AII activity appears to be induced in AI deficiency, it is only partially effective in maintaining urea cycle function. The normal in vivo function of AII is unclear. Arginase deficiency is diagnosed by observing high arginine concentrations on either qualitative or quantitative plasma or urine amino acid analysis. The diagnosis is confirmed by finding markedly decreased or absent arginase activity in an isotopic red blood cell enzymatic assay. The AI gene has been cloned, sequenced, and localised to human chromosome band 6q23. (17 Dec 1997) |
| arginine | <amino acid> An essential amino acid, a major component of proteins and contains the guanido group that has a pKa of greater than 12, so that it carries a permanent positive charge at physiological pH. It becomes an essential amino acid when the body is under stress or is in an injured state. Depressed growth results from lack of dietary arginine. Arginine deficiency syndrome is observed in human babies born with a phosphate synthetase deficiency. Normal growth and development in these infants are achieved by adding arginine to their diet. Arginine deficiency leads to carbamyl phosphate overproduction in the mitochondria due to inadequate ornithine supply. Arginine-deficient diets in males causes decreased sperm counts. Free and bound arginine are found in abundance in human male sperm and arginine has been found to stimulate sperm motility. There are two sources of arginine, arginine in the food chain and free-form arginine from supplements. Food-source arginine is found in abundance in turkey, chicken and other meats. Nonfood-source arginine is called L-arginine and is created through a fermentation process which separates arginine from all other proteins. In the presence of food and other amino acids, L-arginine will act like food-source arginine but when L-arginine is separated from its nutrient boundaries by the removal of all other amino acids, then L-arginine undertakes a different role, becoming capable of crossing the blood-brain barrier and stimulating growth hormone release secreted by the anterior pituitary. Growth hormone serum levels peak during adolescence and begin to drop after age 23. Aging reduces natural growth hormone production, which results in added body fat, reduced muscle tissue, slowed healing, lack of elasticity in the skin and reduced immune function. Human pituitary growth hormone secretion is evidenced in human males, females and children following intravenous administration of 30 grams of arginine (in 30 minutes) in adults and 0.5 grams/kilogram of bodyweight in children. Female response is somewhat higher than male response. Oral administration of L-arginine also results in the release of Human Growth Hormone. Tumour suppression is evidenced in the presence of L-arginine. In the Barbul study, tumours recurred in 100% of the control animals. But in the arginine-supplemented group, only about 60% of the tumours recurred and the animals with tumours survived longer. Supplementation of arginine in the diet inhibits development and increase in size of cancerous tumours, both chemically induced and naturally occurring. Insulin can block growth hormone release, so high serum insulin levels are counterproductive to GH release. Insulin itself is capable of stimulating muscle growth, but it also strongly stimulates fat storage. Muscle growth stimulation from insulin is minuscule compared to muscle growth stimulated by growth hormone. (13 Nov 1997) |