| Howell unit | The quantity of heparin required to keep 1 ml of cat's blood fluid for 24 hr at 0캜; it is equivalent approximately to 0.002 mg of pure heparin. Synonym: Howell unit. (05 Mar 2000) |
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| Howell-Jolly bodies | Spherical or ovoid eccentrically located granules, approximately 1 um in diameter, occasionally observed in the stroma of circulating erythrocytes, especially in stained preparations (as compared with wet unstained films); probably represent nuclear remnants, inasmuch as they can be stained with dyes that are rather specific for chromatin; the significance of the body's is not exactly known; they occur most frequently after splenectomy or in megaloblastic or severe haemolytic anaemia. Synonym: Jolly bodies. (05 Mar 2000) |
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| Howell, William | <person> U.S. Physiologist, 1860-1945. See: Howell unit, Howell-Jolly bodies. (05 Mar 2000) |
| absolute unit | A unit whose value is constant regardless of place or time and not derived from dependent on gravitation. (05 Mar 2000) |
| alexin unit | The smallest amount (highest dilution) of complement that will cause haemolysis of a unit of red blood cells in the presence of a haemolysin unit. Synonym: alexin unit. (05 Mar 2000) |
| Allen-Doisy unit | The quantity of oestrogen capable of producing in a spayed mouse a characteristic change in the vaginal epithelium, namely, disappearance of leukocytes and appearance of cornified cells, as determined by a vaginal smear; equal approximately to one-half of an estrone unit. Synonym: mouse unit. (05 Mar 2000) |
| amboceptor unit | haemolysin unit |
| androgen unit | The androgenic activity of 100 ug (0.1 mg) of crystalline androsterone as assayed by the comb growth response in capons. (05 Mar 2000) |
| antigen unit | The smallest amount of antigen that, in the presence of specific antiserum, will fix 1 complement unit. (05 Mar 2000) |
| antitoxin unit | A unit expressing the strength or activity of an antitoxin; in general, determined with reference to a preserved standard preparation of antitoxin. See: L doses. (05 Mar 2000) |
| antivenene unit | The amount of antivenum which, injected in the ear vein, will protect 1 g weight of rabbit against a fatal dose of snake venom. (05 Mar 2000) |
| atomic mass unit | <chemistry> One-twelfth the mass of a neutral atom of the most abundant isotope of carbon. (16 Dec 1997) |
| Bethesda unit | A measure of inhibitor activity: the amount of inhibitor that will inactivate 50% or 0.5 unit of a coagulation factor during the incubation period. Origin: Bethesda, MD (05 Mar 2000) |
| biological standard unit | A specific quantity of biologically active reference material (antibiotic, antitoxin, enzyme, hormone, vitamin, etc.). (05 Mar 2000) |
| bird unit | A unit of prolactin activity: the minimal quantity of the hormone which will cause a certain increase in weight of the crop gland of pigeons. (05 Mar 2000) |
| Bodansky unit | That amount of phosphatase that liberates 1 mg of phosphorus as inorganic phosphate during the first hour of incubation with a buffered substrate containing sodium beta-glycerophosphate. (05 Mar 2000) |