amyloid
1. Any of a group of chemically diverse proteins that appears microscopically homogeneous, but is composed of linear nonbranching aggregated fibrils arranged in sheets when seen under the electron microscope; it stains dark brown with iodine, produces a characteristic green birefringence in polarized light after staining with Congo red, is metachromatic with either methyl violet (pink-red) or crystal violet (purple-red), and fluoresces yellow after thioflavine T staining; a. occurs characteristically as pathologic extracellular deposits (amyloidosis), especially in association with reticuloendothelial tissue; the chemical nature of the proteinaceous fibrils is dependent upon the underlying disease process. 2. Resembling or containing starch. [amylo- + G. eidos, resemblance]

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am·y·loid 'am-ə-.lȯid n
1) a nonnitrogenous starchy food
2) a waxy translucent substance consisting primarily of protein that is deposited in some animal organs and tissue under abnormal conditions (as in Alzheimer's disease) see BETA-AMYLOID
amyloid adj

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n.
a glycoprotein, resembling starch, that is deposited in the internal organs in amyloidosis. b-amyloid protein has been found in the brains of Alzheimer's patients but the significance of this is unclear.

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am·y·loid (amґə-loid) [amylo- + -oid] 1. resembling starch; characterized by starchlike staining properties. 2. a substance produced by the action of sulfuric acid on cellulose, which gives a blue color when treated with iodine. 3. the pathologic extracellular proteinaceous substance deposited in amyloidosis; it is a waxy eosinophilic material that exhibits a green birefringence under polarized light when stained with Congo red. Amyloid deposits are composed primarily of straight, nonbranching fibrils 7.5–10 nm in diameter and of indefinite length, arranged either in bundles or in a feltlike meshwork; each fibril is composed of identical polypeptide chains arranged in stacked antiparallel β-pleated sheets. Although different forms have similar appearance, the protein in each is different.

Medical dictionary. 2011.

Look at other dictionaries:

  • Amyloid — (Hydrocellulose). 1. Löst man Cellulose, z.B. Baumwolle, in konzentrierter Schwefelsäure, so wird durch einen baldigen Wasserzusatz eine Gallerte gefällt, die sich auf Zusatz von konzentrierter Schwefelsäure mit einer Jodlösung blau färbt, wie… …   Lexikon der gesamten Technik

  • Amyloid — Am y*loid, Amyloidal Am y*loid al, a. [L. amylum starch + oid.] Resembling or containing amyl; starchlike. [1913 Webster] {Amyloid degeneration} (Med.), a diseased condition of various organs of the body, produced by the deposit of an albuminous… …   The Collaborative International Dictionary of English

  • Amyloid — Am y*loid ([a^]m [y^]*loid), n. 1. A non nitrogenous starchy food; a starchlike substance. [1913 Webster] 2. (Med.) The substance deposited in the organs in amyloid degeneration. [1913 Webster] …   The Collaborative International Dictionary of English

  • Amyloid — Amyloīd, s. Zellulose; auch eine mattglänzende, durchscheinende, bei der Amyloid oder Speckentartung in Leber, Milz und Nieren sich bildende und diese Organe nach und nach unfähig zu ihren Verrichtungen machende Substanz, ein Eiweißkörper …   Kleines Konversations-Lexikon

  • Amyloid — (griech.: Amylo = Stärke) bedeutet stärkeähnlich, auch stärkeähnliche Substanz. Es ist ein Fachbegriff in der Mykologie und bezeichnet die Anfärbbarkeit von Geweben mit Iodreagenzien: Amyloidität Medizin und bezeichnet bestimmte, abnorm… …   Deutsch Wikipedia

  • Amyloid — Amyloid, als Pflanzenstoff, s.u. Pflanzen S. 11 …   Pierer's Universal-Lexikon

  • Amyloīd — Amyloīd, s. Zellulose …   Meyers Großes Konversations-Lexikon

  • amyloid — (adj.) starch like, 1857, coined in German (1839) from L. amylum (see AMYL (Cf. amyl)) + Greek derived suffix OID (Cf. oid). The noun is attested from 1872 …   Etymology dictionary

  • amyloid — [am′ə loid΄] n. 1. a starchy food or substance 2. a nearly transparent, waxy deposit resulting from degeneration of bodily tissues: a complex protein …   English World dictionary

  • Amyloid — Amyloids are insoluble fibrous protein aggregates sharing specific structural traits. Abnormal accumulation of amyloid in organs may lead to amyloidosis, and may play a role in various other neurodegenerative diseases. Definition controversyThe… …   Wikipedia

  • amyloid — Glycoprotein deposited extracellularly in tissues in amyloidosis. The glycoprotein may either derive from light chain of immunoglobulin (AIO (amyloid of immune origin): 5 18 kD glycoprotein; product of a single clone of plasma cells, the N… …   Dictionary of molecular biology

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