| Hapsburg lip | Prognathism and pouting lower lip, characteristic of the Hispano-Austrian imperial dynasty. (05 Mar 2000) |
|---|---|
| hapten | <immunology, molecular biology> Could be considered an isolated epitope: although a hapten (by definition) has an antibody directed against it, the hapten alone will not induce an immune response if injected into an animal, it must be conjugated to a carrier (usually a protein). The hapten constitutes a single antigenic determinant, perhaps the best known example is dinitro phenol (DNP) that can be conjugated to BSA and against which antiDNP antibodies are produced (antibodies to the BSA can be adsorbed out). Because the hapten is monovalent, immune complex formation will be blocked if the soluble hapten is present as well as the hapten carrier conjugate (assuming there is more than one hapten per carrier then an immune precipitate can be formed). Competitive inhibition by the soluble small molecule is sometimes referred to as haptenic inhibition and this term has carried over into lectin mediated haemagglutination where monosaccharides are added to try to block haemagglutination: the blocking sugar defines the specificity of the lectin. (18 Nov 1997) |
| hapten inhibition of precipitation | Inhibition of precipitation that occurs when the precipitin has combined with hapten of the same specificity as the subsequently added antigen. (05 Mar 2000) |
| haptenic inhibition | <immunology, molecular biology> Could be considered an isolated epitope: although a hapten (by definition) has an antibody directed against it, the hapten alone will not induce an immune response if injected into an animal, it must be conjugated to a carrier (usually a protein). The hapten constitutes a single antigenic determinant, perhaps the best known example is dinitro phenol (DNP) that can be conjugated to BSA and against which antiDNP antibodies are produced (antibodies to the BSA can be adsorbed out). Because the hapten is monovalent, immune complex formation will be blocked if the soluble hapten is present as well as the hapten carrier conjugate (assuming there is more than one hapten per carrier then an immune precipitate can be formed). Competitive inhibition by the soluble small molecule is sometimes referred to as haptenic inhibition and this term has carried over into lectin mediated haemagglutination where monosaccharides are added to try to block haemagglutination: the blocking sugar defines the specificity of the lectin. (18 Nov 1997) |
| haptens | Small antigenic determinants capable of eliciting an immune response only when coupled to a carrier. Haptens bind to antibodies but by themselves cannot elicit an antibody response. (12 Dec 1998) |
| hapteron | <botany> A holdfast, a specialised root-like projection that functions to anchor a plant. (09 Oct 1997) |
| haptic hallucination | The sensation of touch in the absence of stimuli; may be seen in alcoholic delirium tremens. (05 Mar 2000) |
| haptics | The science concerned with the tactile sense. Origin: G. Hapto, to grasp, touch (05 Mar 2000) |
| haptodysphoria | An unpleasant sensation derived from touching certain objects. Origin: G. Hapto, to touch, + dysphoria (05 Mar 2000) |
| haptoglobin | <protein> Acid _2 plasma glycoprotein that binds to oxyhaemoglobin that is free in the plasma and the complex is then removed in the liver. Tetrameric (2 _, 2 _ subunits): the existence of two different _ chains in humans means that haptoglobins can exist in three variants in heterozygotes. (18 Nov 1997) |
| haptoglobins | Plasma glycoproteins that form a stable complex with haemoglobin to aid the recycling of haem iron. They are encoded in man by a gene on the short arm of chromosome 16. (12 Dec 1998) |
| haptometer | Instrument for measuring sensitivity to touch. Origin: G. Hapto, to touch, + metron, measure (05 Mar 2000) |
| haptonema | <cell biology> Filament extending between the paired flagella of certain unicellular algae (haptophytes). Supported by 6 or 7 microtubules (not in an axoneme like array) and apparently used for capturing prey in a manner analogous to the axopodia of heliozoa. (18 Nov 1997) |
| haptotaxis | <cell biology> Strictly speaking, a directed response of cells in a gradient of adhesion, but often loosely applied to situations where an adhesion gradient is thought to exist and local trapping of cells seems to occur. (18 Nov 1997) |
| haptotropism | <biology> An orientation response of an organism to stimulation by touch. (09 Oct 1997) |