| Lancefield | Rebecca Craighill, U.S. Bacteriologist, *1895. See: Lancefield classification. (05 Mar 2000) |
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| Lancefield classification | A serologic classification dividing haemolytic streptococci into groups (A to O) which bear a definite relationship to their sources, based upon precipitation tests depending upon group-specific substances that are carbohydrate in nature; e.g., Group A contains strains pathogenic for man; B, strains from mastitis in cows and from normal milk, including a few strains from the human throat and vagina; C, strains from various lower animals, including a number from cattle; D, strains from cheese; E, strains from certified milk; F, strains mainly from the human throat, associated with tonsillitis; G, strains from man, a few from monkeys and dogs; and H, K, and O, nonpathogenic strains from normal human respiratory tracts. (05 Mar 2000) |
| ammonium sulphate precipitation | <technique> In this technique, ammonium sulphate is used to make proteins precipitate out of a solution, the proteins are then collected by centrifugation. (09 Oct 1997) |
| capsular precipitation reaction | Swelling of the capsule surrounding a bacterium as a result of interaction with anticapsular antibody, consequently the capsule becomes more refractile and conspicuous. (18 Nov 1997) |
| precipitation | The act or process of precipitating. Origin: L. Praecipitatio (18 Nov 1997) |
| precipitation curve | A graph of the quantity of precipitate formed as a function of the quantity of antigen added during the titration of an antibody with an antigen. Synonym: Heidelberger curve. (05 Mar 2000) |
| precipitation test | An in vitro test in which antigen is in soluble form and precipitates when it combines with added specific antibody in the presence of an electrolyte. See: gel diffusion precipitin tests, ring precipitin test. Synonym: precipitation test. (05 Mar 2000) |
| 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) |
| double antibody precipitation | A method of separating antibody-bound antigen (e.g., insulin) from free antigen by precipitating the former with antibody specific for immunoglobulin. Synonym: double antibody immunoassay, double antibody method. (05 Mar 2000) |
| immune precipitation | <immunology> The precipitation of a multivalent antigen by a bivalent antibody, resulting in the formation of a large complex. The antibody and antigen must be soluble. Precipitation usually occurs when there is near equivalence between antibody and antigen concentrations. (18 Nov 1997) |
| isopropanol precipitation test | A test using the principle that the internal bonds of haemoglobin are weakened by nonpolar solvents; thus, unstable haemoglobins will precipitate more rapidly than other haemoglobins in isopropanol. (05 Mar 2000) |