| retard | <pharmacology> Characterised by retarded action, said of a drug when it is supposed to exercise its maximum effect later in the cycle. (10 Mar 1998) |
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| RNA caps | Compounds with the general structure 7-methyl-5'-guanosine triphosphate-5'-x which modify the 5' end of eukaryotic cellular and viral messenger RNA and some heterogeneous nuclear rnas. These compounds, which are positively charged, protect the above specified rnas at their termini against attack by phosphatases and other nucleases and promote mRNA function at the level of initiation of translation. Analogs of the RNA caps (RNA cap analogs), which lack the positive charge, inhibit the initiation of protein synthesis. (12 Dec 1998) |
| dental caps | <veterinary> Deciduous cheek teeth in the horse which remain attached to erupting permanent teeth. (05 Mar 2000) |
| iso- | 1. <prefix> A prefix that means equal or like. 2. <chemistry> A prefix indicating isomer of (isomerism); e.g., isocyanate vs. cyanate. 3. <immunology> A prefix designating sameness with respect to species; in recent years, the meaning has shifted to sameness with respect to genetic constitution of individuals. Origin: G. Isos, equal (20 Jun 2000) |
| iso-osmotic | <physiology> Having the same total osmotic pressure or osmolality as another fluid (ordinarily intracellular fluid); such a fluid is not isosmotic if it includes solutes that freely permeate cell membranes. Synonym: iso-osmotic. (05 Mar 2000) |