| tetanus toxin | <protein> Neurotoxin released by Clostridium tetani, becomes active when peptide cleaved proteolytically to heavy (100 kD) and light (50 kD) chains held together by disulphide bond. Heavy chain binds to disialogangliosides (GD2 and GD1b) and part of the peptide (the amino terminal B fragment) forms a pore: light chain is a zinc endopeptidase that specifically attacks synaptobrevin, to block neurotransmitters. See: botulinum toxin (18 Nov 1997) |
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| toxin | <pharmacology> A poison, frequently used to refer specifically to a protein produced by some higher plants, certain animals and pathogenic bacteria, which is highly toxic for other living organisms. Such substances are differentiated from the simple chemical poisons and the vegetable alkaloids by their high molecular weight and antigenicity. Origin: Gr toxikon = arrow poison, from Gr. Toxikos = of or for a bow (18 Nov 1997) |
| toxin spectrum | A figure in the form of a spectrum used by Ehrlich to represent the neutralizing power of antitoxin in the presence of toxin, toxone, etc. (05 Mar 2000) |
| erythrogenic toxin | <protein> Toxin produced by strains of Streptococcus pyogenes responsible for scarlet fever. Three antigenic variants of the toxin are known. It is a small protein that is complexed with hyaluronic acid and can intensify the effects of other toxins such as endotoxin and streptolysin O. (18 Nov 1997) |
| extracellular toxin | <protein> Toxin released from gram-positive and gram-negative bacteria as opposed to endotoxins that form part of the cell wall. Examples are cholera, pertussis and diphtheria toxins. Usually specific and highly toxic. (18 Nov 1997) |
| 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) |