amyloid

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.

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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.).

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am·y·loid (m-loid)

n.

1. A starchlike substance.

2. A hard, waxy deposit consisting of protein and polysaccharides resulting from the degeneration of tissue.

adj.

Starchlike.

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Amyloid

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

Mentioned in: Amyloidosis, Cerebral Amyloid Angiopathy, Familial Mediterranean Fever

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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.

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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.

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amyloid (am´loid´),

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.

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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.

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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.

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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.