| free thyroxine index | An arbitrary value obtained by multiplying the triiodothyronine uptake by the serum thyroxine concentration; it largely corrects for variations in thyroid-bound globulin concentration by providing a clinically valid estimate of the physiologically active free thyroxine; direct assay or laboratory measurement of free serum thyroxine yields a more accurate value. (05 Mar 2000) |
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| free villus | A chorionic villus that is not attached to the decidua basalis, but is "free" in the maternal blood of the intervillous spaces. Synonym: floating villus. (05 Mar 2000) |
| free water | Water in the body that can be removed by ultrafiltration and in which substances can be dissolved. (05 Mar 2000) |
| free water clearance | The amount of water excreted in the urine beyond that which would accompany the excreted solutes if the urine were isosmotic with plasma; it represents the loss of body water in excess of solute tending to raise body osmolality and making urine hyposmotic. Unlike other clearance's, it is calculated by subtracting the osmolal clearance from the actual volume of urine excreted per minute. A negative value for free water clearance represents the amount of water that the body has reclaimed from isosmotic tubule fluid to make the urine hyperosmotic and to lower body osmolality. (05 Mar 2000) |
| free wave | <radiobiology> A wave (for example, electromagnetic) traveling in a homogeneous infinite medium (no boundary conditions). (09 Oct 1997) |
| free will | 1. A will free from improper coercion or restraint. "To come thus was I not constrained, but did On my free will." (Shak) 2. The power asserted of moral beings of willing or choosing without the restraints of physical or absolute necessity. Source: Websters Dictionary (01 Mar 1998) |
| administration, oral | The giving of drugs, chemicals, or other substances by mouth. (12 Dec 1998) |
| amino- | <prefix> Prefix denoting a compound containing the radical, -NH2. Origin: an(monia) + in(e) + -o- (05 Mar 2000) |
| amino acids | Organic compounds that generally contain an amino (-nh2) and a carboxyl (-cooh) group. Twenty alpha-amino acids are the subunits which are polymerised to form proteins. (12 Dec 1998) |
| amino acids, branched-chain | Amino acids which have a branched carbon chain. (12 Dec 1998) |
| amino acids, cyclic | A class of amino acids characterised by a closed ring structure. (12 Dec 1998) |
| amino acids, peptides, and proteins | Amino acids and chains of amino acids connected by peptide linkages. (12 Dec 1998) |
| amino acyl-tRNA ligases | <enzyme> Any of the group of ligases that catalyses the ATP-driven formation of a bond between an amino acid and a trna, activating the amino acids as a step in protein synthesis. Individual enzymes are highly specific for one amino acid and for any trna corresponding to that amino acid. Registry number: EC 6.1.1. (12 Dec 1998) |
| amino alcohols | Compounds possessing both a hydroxyl (-oh) and an amino group (-nh2). (12 Dec 1998) |
| amino group | <biochemistry> An -NH2 group. Organic compounds which have this group are called amines. (09 Oct 1997) |