| complement fixation | <immunology> Binding of complement as a result of its interaction with immune complexes (the classical pathway) or particular surfaces (alternative pathway). (18 Nov 1997) |
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| complement fixation tests | Serologic tests based on inactivation of complement by the antigen-antibody complex (stage 1). Binding of free complement can be visualised by addition of a second antigen-antibody system such as red cells and appropriate red cell antibody (haemolysin) requiring complement for its completion (stage 2). Failure of the red cells to lyse indicates that a specific antigen-antibody reaction has taken place in stage 1. If red cells lyse, free complement is present indicating no antigen-antibody reaction occurred in stage 1. (12 Dec 1998) |
| complement-fixation reaction | <immunology> Binding of complement as a result of its interaction with immune complexes (the classical pathway) or particular surfaces (alternative pathway). (18 Nov 1997) |
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| complement-fixation test | An immunological test for determining the presence of a particular antigen or antibody when one of the two is known to be present, based on the fact that complement is "fixed" in the presence of antigen and its specific antibody. See: Bordet-Gengou phenomenon. (05 Mar 2000) |
| thyrotoxic complement-fixation factor | A form of thyrotoxin; an antigen found most readily in thyroid tissue from thyrotoxic individuals; known to be chemically and immunologically distinct from thyroglobulin, and fixes complement when combined with antibody related to the gamma-globulin fraction of serum. With the exception of extremely small concentrations, the antigen is rarely found in normal glands or in diseased glands that are not associated with thyrotoxicosis; it is probably an intracellular substance (possibly a constituent of the "microsomal fraction"), and does not contain iodine in significant quantity. Not related to the complement-fixation reaction occurring with serum in Hashimoto's disease, in which the antigen is thyroglobulin. (05 Mar 2000) |
| ammonia fixation | The utilization of ammonia (or ammonium ions) in the net synthesis of nitrogen-containing molecules; e.g., glutamine synthetase. Synonym: ammonia fixation. (05 Mar 2000) |
| bifoveal fixation | A condition in which both eyes are simultaneously directed to the same target. Synonym: bifoveal fixation. (05 Mar 2000) |
| binocular fixation | A condition in which both eyes are simultaneously directed to the same target. Synonym: bifoveal fixation. (05 Mar 2000) |
| carbon fixation | <plant biology> The process by which photosynthetic organisms such as plants turn inorganic carbon (usually carbon dioxide) into organic compounds (us. Carbohydrates). (09 Oct 1997) |
| mandibulomaxillary fixation | Fixation of fractures of the mandible or maxilla by applying elastic bands or stainless steel wire between the maxillary and mandibular arch bars or other types of splint. Synonym: mandibulomaxillary fixation, maxillomandibular fixation. (05 Mar 2000) |
| genes, nitrogen fixation | Regulatory and structural genes present in certain bacteria, algae and fungi that control the conversion of atmospheric nitrogen into biologically usable compounds; include nif structural genes (e.g., nifd, nifh) for nitrogenase and nitrate reductase as well as regulator genes nifa, nifb, ntra, ntrb, ntrc. Some are responsible for regulating transcription of genes involved in the assimilation of poor nitrogen sources in enteric bacteria. (12 Dec 1998) |
| genetic fixation | The increase of the frequency of a gene by genetic drift until no other allele is preserved in a specific finite population. (05 Mar 2000) |
| Gibney's fixation bandage | A herring-bone strapping of the foot and leg for sprain of the ankle. (05 Mar 2000) |
| maxillomandibular fixation | Fixation of fractures of the mandible or maxilla by applying elastic bands or stainless steel wire between the maxillary and mandibular arch bars or other types of splint. Synonym: mandibulomaxillary fixation, maxillomandibular fixation. (05 Mar 2000) |
| Roger-Anderson pin fixation appliance | An appliance used in extraoral fixation of mandibular fractures and prognathic corrections in which pins placed in the bone segments are joined by metal connecting rods. See: external pin fixation. (05 Mar 2000) |
| circumalveolar fixation | Stabilization of a fracture segment or surgical splint by wire passed through and around the dental alveolar process. (05 Mar 2000) |
| circummandibular fixation | Stabilization of a fracture segment or surgical splint by wire passed around the mandible. (05 Mar 2000) |