| essential amino acid | <biochemistry> Those amino acids that cannot be synthesised by an organism and must therefore be present in the diet. The term is often applied anthropocentrically to those amino acids required by humans (Ileu, Leu, Lys, Met, Phe, Thr, Try, & Val), though rats need two more (Arg & His). (18 Nov 1997) |
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| excitatory amino acid | <biochemistry> The naturally occurring amino acids L glutamate and L aspartate and their synthetic analogues, notably kainate, quisqualate and NMDA. They have the properties of excitatory neurotransmitters in the CNS, may be involved in long-term potentiation and can act as excitotoxins. at least three classes of EAA receptor have been identified, the agonists of the N type receptor are L aspartate, NMDA and ibotenate, the agonists of the Q type receptor are L glutamate and quisqualate, agonists of the K type are L glutamate and kainate. All three receptor types are found widely in the CNS and particularly the telencephalon, N and Q type receptors tend to occur together and may interact, their distribution is complementary to the K type receptors. The ion fluxes through the Q and K receptors are relatively brief, whereas the flux through the N type is longer and carries a significant amount of calcium. Additionally the N type receptor is blockaded by magnesium near the resting potential and thus shows voltage gated ion channel properties, leading to a regenerative response, this is why N type receptors have been linked to long-term potentiation. Invertebrate glutamate receptors may not have the same properties as those described above. (18 Nov 1997) |
| excitatory amino acid agents | Drugs used for their actions on any aspect of excitatory amino acid neurotransmitter systems. Included are drugs that act on excitatory amino acid receptors, affect the life cycle of excitatory amino acid transmitters, or affect the survival of neurons using excitatory amino acids. (12 Dec 1998) |
| excitatory amino acid agonists | Drugs that bind to and activate excitatory amino acid receptors. (12 Dec 1998) |
| excitatory amino acid antagonists | Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists. (12 Dec 1998) |
| 1-carbamoyl-L-amino acid amidohydrolase | <enzyme> From bacillus stearothermophilus; amino acid sequence given in first source Registry number: EC 3.5.1.- Synonym: carbamoyl l-aa amidohydrolase, n-carbamyl-l-amino acid amidohydrolase (26 Jun 1999) |
| acetate replacement factor | <biochemistry> 1,2 dithiolane 3 valeric acid. Regarded as a coenzyme in the oxoglutarate dehydrogenase complex of the citric acid cycle. Involved generally in oxidative decarboxylations of _ keto acids. A growth factor for some organisms. (18 Nov 1997) |
| arthroplasty, replacement | Partial or total replacement of a joint. (12 Dec 1998) |
| arthroplasty, replacement, hip | Replacement of the hip joint. (12 Dec 1998) |
| arthroplasty, replacement, knee | Replacement of the knee joint. (12 Dec 1998) |
| renal replacement therapy | Procedures which temporarily or permanently remedy insufficient cleansing of body fluids by the kidneys. (12 Dec 1998) |
| replacement | 1. The act of replacing. 2. <chemistry> The removal of an edge or an angle by one or more planes. Source: Websters Dictionary (01 Mar 1998) |
| replacement bone | A bone that develops in a cartilage environment after the latter is partially or entirely destroyed by calcification and subsequent resorption. Synonym: cartilage bone, replacement bone. (05 Mar 2000) |
| replacement fibrosis | The formation of fibrous tissue that occupies sites where various other cells and tissues have become atrophied, or degenerated and necrotic. (05 Mar 2000) |
| replacement therapy | Therapy designed to compensate for a lack or deficiency arising from inadequate nutrition, from certain dysfunctions (e.g., glandular hyposecretion), or from losses (e.g., haemorrhage); replacement may be physiological or may entail administration of a substitute (e.g., a synthetic oestrogen in place of estradiol). (05 Mar 2000) |