amyloid

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amyloid

 [am´ĭ-loid]
1. resembling starch; characterized by starchlike staining properties.
2. the pathologic extracellular proteinaceous substance deposited in amyloidosis; it is a waxy eosinophilic material. Amyloid deposits are composed primarily of straight, nonbranching fibrils arranged either in bundles or in a feltlike meshwork; each fibril is composed of identical polypeptide chains in stacked sheets. There are two major biochemical types of amyloid protein: amyloid light chain protein and amyloid A protein, as well as others seen less often.

am·y·loid

(am'i-loyd),
1. Any of a group of chemically diverse proteins that appear microscopically homogeneous but are composed of linear nonbranching aggregated fibrils arranged in sheets when seen under the electron microscope; amyloid 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.
2. The pathologic extracellular proteinaceous substance deposited in amyloidosis. There are two major types of amyloid protein: amyloid light chain protein that occurs in primary amyloidosis and amyloid, a protein that occurs in reactive systemic amyloidosis.
3. Resembling or containing starch.
[amylo- + G. eidos, resemblance]

amyloid

/am·y·loid/ (am´ĭ-loid)
1. starchlike; amylaceous.
2. the pathologic, extracellular, waxy, amorphous substance deposited in amyloidosis, being composed of fibrils in bundles or in a meshwork of polypeptide chains.

AA amyloid  a pathological fibrillar low-molecular-weight protein formed by cleavage of serum amyloid A (SAA) protein. It is deposited in the tissues secondary to chronic inflammatory conditions; see secondary amyloidosis, under amyloidosis.
Aβ amyloid  an abnormal peptide found in aggregates in the cerebrovascular walls and the cores of the plaques in Alzheimer's disease; it is derived from amyloid precursor protein.
AL amyloid  a pathological fibrillar low-molecular-weight protein derived from circulating monoclonal immunoglobulin light chains, usually λ chains; it may be composed of whole chains, fragments, or both. It is deposited in the tissues in primary amyloidosis (q.v.).

amyloid

(ăm′ə-loid′)
n.
1. A starchlike substance.
2.
a. An insoluble, fibrous structure consisting chiefly of an aggregation of proteins arranged in beta sheets, forming extracellular deposits in organs or tissues and characteristic of certain diseases such as Alzheimer's disease and Parkinson's disease.
b. The substance that makes up such a structure.
adj.
1. Starchlike.
2. Being or related to proteinaceous amyloid: amyloid plaque.

amyloid

[am′iloid]
Etymology: Gk, amylon, starch, eidos, form
1 pertaining to or resembling starch.
2 a starchlike protein-carbohydrate complex deposited abnormally in some tissues during certain chronic disease states, such as amyloidosis, rheumatoid arthritis, tuberculosis, and Alzheimer's disease.

amyloid

β-fibrillosis A homogeneous, extracellular glycoprotein with a fibrillary ultrastructure, derived either from
1. The N-terminal of lambda or kappa Ig light chains–amyloid of immune origin, a 5-18 kD glycoprotein produced by a single clone of plasma cells or.
2. Amyloid of unknown origin, from serum amyloid A–SAA, an acute phase protein that ↑ sharply during inflammation; all amyloids have a common molecular theme, that of the β-pleated protein sheet, demonstrable by X-ray crystallography and responsible for amyloid's Congo red staining and resistance to proteolytic digestion See Beta amyloid. Cf Alzhemier's disease.

am·y·loid

(am'i-loyd)
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 color 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; amyloid occurs characteristically as pathologic extracellular deposits (amyloidosis), especially in association with reticuloendothelial tissue; the chemical nature of the proteinaceous fibrils is dependent on the underlying disease process.
2. Resembling or containing starch.
[amylo- + G. eidos, resemblance]

amyloid

One of a range of proteins deposited in the brain in spongiform encephalopathies such as CREUTZFELDT-JAKOB DISEASE, in other degenerative brain disorders such as ALZHEIMER'S DISEASE, and in the tissues in a wide range of long-term suppurative disorders (see AMYLOIDOSIS). It is a hard, waxy proteinaceous substance in the form of straight, rigid, non-branching fibrils, 10–15 nm in diameter that are insoluble in water and relatively resistant to breakdown by proteolytic enzymes. There is a considerable range of amyloid proteins mainly specific for the different conditions in which amyloid is deposited. From the Latin amylum , starch.

Amyloid

Amyloid protein resembles a starch and is deposited in tissues during the course of certain chronic diseases.

amyloid

a group of chemically diverse proteins formed as pathological extracellular deposits in the walls of blood vessels; characteristic of amyloidosis

am·y·loid

(am'i-loyd)
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; occurs characteristically as pathologic extracellular deposits (amyloidosis), especially in association with reticuloendothelial tissue; the chemical nature of the proteinaceous fibrils, depends on the underlying disease process.
[amylo- + G. eidos, resemblance]

amyloid (am´əloid´),

n a starchlike protein-carbohydrate complex that is deposited abnormally in some tissues during certain chronic disease states, such as amyloidosis, rheumatoid arthritis, and tuberculosis.

amyloid

1. starchlike; amylaceous.
2. an eosinophilic homogeneous hyaline material deposited extracellularly in glomeruli in particular. Because of its characteristic β-pleated pattern it is resistant to proteolysis and is insoluble.

amyloid AA
derived from serum amyloid A protein in reactive systemic (secondary) amyloidosis.
amyloid AL
derived from immunoglobulin light chains in immunocytic or primary amyloidosis; usually associated with myeloma.
islet amyloid polypeptide
a polypeptide produced in the pancreatic β-cells and co-released with insulin; inhibits insulin release and may counteract insulin action in peripheral tissues. Deposits are found in the pancreas of cats with diabetes mellitus.