| competition | <zoology> A type of organism interaction which can be either between members of the same species or members of different species. The relationship occurs when commodities (like food, mates, shelters, etc.) are scarce and there are not enough to go around for all members which need them. In general, all involved members of the relationship are harmed by this interaction. (05 Jan 1998) |
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| competition hybridisation | <molecular biology, technique> A lab technique used to determine how similar two strands of single-stranded nucleic acids are to each other by putting them with a third strand (called a standard) and observing how well they can bond with each other to become double-stranded (how well they hybridize). (05 Jan 1998) |
| competitive antagonist | An antimetabolite. (05 Mar 2000) |
| competitive behaviour | The direct struggle between individuals for environmental necessities or for a common goal. (12 Dec 1998) |
| competitive bidding | Pricing statements presented by more than one party for the purpose of securing a contract. (12 Dec 1998) |
| competitive binding assay | General term for an assay in which a binder competes for labelled versus unlabelled ligand; following separation of free and bound ligand, the ligand (the analyte assayed) is quantitated by relating bound and unbound ratios to known standards. See: enzyme-linked immunosorbent assay, radioreceptor assay, immunoassay, enzyme-multiplied immunoassay technique, radioimmunoassay. Synonym: displacement analysis, saturation analysis. (05 Mar 2000) |
| competitive inhibition | <chemistry> Inhibitor that occupies the active site of an enzyme or the binding site of a receptor and prevents the normal substrate or ligand from binding. at sufficiently high concentration of the normal ligand inhibition is lost: the Km is altered by the competitive inhibitor, but the Vmax remains the same. (05 Jan 1998) |
| competitive medical plans | Alternative health care delivery mechanisms, such as preferred provider organizations or other health insurance services or prepaid plans (other than health maintenance organizations), that meet medicare qualifications for a risk-sharing contract. (12 Dec 1998) |
| competitor DNA | DNA from a test organism that is denatured and then used in in vitro hybridization experiments in which it competes with DNA (homologous) from a reference organism; used to determine the relationship of the test organism to the reference organism. (05 Mar 2000) |
| complaint | A disorder, disease, or symptom, or the description of it. Origin: O. Fr. Complainte, fr. L. Complango, to lament (05 Mar 2000) |
| complement | <immunology> A term originally used to refer to the heat labile factor in serum that causes immune cytolysis, the lysis of antibody coated cells and now referring to the entire functionally related system comprising at least 20 distinct serum proteins that is the effector not only of immune cytolysis but also of other biologic functions. Complement activation occurs by two different sequences, the classic and alternative pathways. The proteins of the classic pathway are termed components of complement and are designated by the symbols C1 through C9. C1 is a calcium dependent complex of three distinct proteins C1q, C1r and C1s. The proteins of the alternative pathway (collectively referred to as the properdin system) and complement regulatory proteins are known by semisystematic or trivial names. Fragments resulting from proteolytic cleavage of complement proteins are designated with lower case letter suffixes, for example, C3a. Inactivated fragments may be designated with the suffix i, for example C3bi. Activated components or complexes with biological activity are designated by a bar over the symbol for example C1 or C4b, 2a. The classic pathway is activated by the binding of C1 to classic pathway activators, primarily antigen-antibody complexes containing IgM, IgG1, IgG3, C1q binds to a single IgM molecule or two adjacent IgG molecules. The alternative pathway can be activated by IgA immune complexes and also by nonimmunologic materials including bacterial endotoxins, microbial polysaccharides and cell walls. Activation of the classic pathway triggers an enzymatic cascade involving C1, C4, C2 and C3, activation of the alternative pathway triggers a cascade involving C3 and factors B, D and P. Both result in the cleavage of C5 and the formation of the membrane attack complex. Complement activation also results in the formation of many biologically active complement fragments that act as anaphylatoxins, opsonins or chemotactic factors. (05 Jan 1998) |
| complement 1 | The first complement component to act in the cytolysis reaction. It is a trimolecular complex held together with ca ions and when activated, has esterase activity which initiates the next step in the sequence. (12 Dec 1998) |
| complement 1 inactivators | Compounds which inhibit, antagonise, or inactivate complement 1. A well-known inhibitor is a serum glycoprotein believed to be alpha-2-neuroaminoglycoprotein. It inhibits the activated (esterase) form of complement 1 as well as kinin-forming, coagulation, and fibrinolytic systems. Deficiency of this inactivator has been found in patients with hereditary angioneurotic oedema. These compounds are members of the serpin superfamily. (12 Dec 1998) |
| complement 1q | <chemical> Subcomponent of complement 1 (c1) which recognises and binds to the heavy chain of IgG or IgM initiating the classical complement pathway. The interaction of c1q and immunoglobulin activates c1r and c1s. The activated c1r and c1s molecules are cleaved off the complex by c1-inhibitor, allowing the collagen-like region of c1q to become accessible for interaction with cell membrane c1q receptors. Chemical name: Complement C1q (12 Dec 1998) |
| complement 1r | <enzyme> Subcomponent of complement 1 which, when activated by c1q, activates subcomponent c1s by proteolytic cleavage. Registry number: EC 3.4.21.41 (12 Dec 1998) |