| diphtheria toxin | <protein> An ab exotoxin (62 kD) coded by _ corynephage of virulent Corynebacterium diphtheriae strains (that can produce a repressor of toxin production). The B subunit binds to receptors on the surface of the target cell and facilitates the entry of the enzymically active A subunit (21 kD) that ADP ribosylates elongation factor 2, thereby halting mRNA translation. (18 Nov 1997) |
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| intracellular toxin | <protein> Heat stable polysaccharide like toxin bound to a bacterial cell. The term is used more specifically to refer to lipopolysaccharide (LPS) of the outer membrane of gram-negative bacteria. There are three parts to the molecule, the Lipid A (six fatty acid chains linked to two glucosamine residues), the core oligosaccharide (branched chain of ten sugars) and a variable length polysaccharide side chain (up to 40 sugar units in smooth forms) that can be removed without affecting the toxicity (rough LPS). Some endotoxin is probably released into the medium and endotoxin is responsible for many of the virulent effects of gram-negative bacteria. (18 Nov 1997) |
| t-2 toxin | <chemical> (3 alpha,4 beta,8 alpha)-12,13-epoxytrichothec-9-ene-3,4,8,15-tetrol 4,15-diacetate 8-(3-methylbutanoate). A potent mycotoxin produced in feedstuffs by several species of the genus fusarium. It elicits a severe inflammatory reaction in animals and has teratogenic effects. Chemical name: Trichothec-9-ene-3,4,8,15-tetrol, 12,13-epoxy-, 4,15-diacetate 8-(3-methylbutanoate), (3alpha,4beta,8alpha)- (12 Dec 1998) |
| 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) |
| 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) |
| acrocephalosyndactyly type 1 | <paediatrics> An inherited disease (autosomal dominant) or a spontaneously occurring disease characterised by a peaked head and unusual facial appearance, due to the premature closure of the cranial sutures. A skull X-ray can confirm the diagnosis and treatment is surgical. Inheritance: autosomal dominant. (27 Sep 1997) |
| Alzheimer type I astrocyte | Enlarged frequently multinucleated astrocytes, seen in progressive multifocal leukoencephalopathy. (05 Mar 2000) |
| Alzheimer type II astrocyte | Enlarged astrocytes with vesicular nuclei and one or more small basophilic nucleoli, seen in hepatocerebral disease and Wilson's disease. (05 Mar 2000) |
| American Type Culture Collection | <cell culture> A key resource for cultured cells, located in Rockville, USA. (12 Dec 1998) |
| Antoni type A neurilemoma | <tumour> Relatively solid or compact arrangement of neoplastic tissue that consists of Schwann cells arranged in twisting bundles and associated with delicate reticulin fibres; the nuclei of the Schwann cells are frequently grouped in parallel rows (so-called palisades), and the nuclei and fibres sometimes form exaggerated tactile corpuscles, called Verocay bodies. (05 Mar 2000) |
| Antoni type B neurilemoma | <tumour> Relatively soft or loose arrangement of neoplastic tissue that consists of Schwann cells in a haphazard or nondescript type of arrangement among reticulin fibres and tiny cystlike foci; fat-laden macrophages may be observed in some of the larger neoplasms. (05 Mar 2000) |
| arthus-type reaction's | Reaction's in man and other species that result from the same basic immunologic (allergic) mechanism which evokes, in the rabbit, the typical Arthus phenomenon. See: immune complex disease. (05 Mar 2000) |