Amyloid: Amyloidosis

Amyloid: Amyloidosis


Definition
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Amyloidosis is a clinical disorder caused by extracellular deposition of insoluble abnormal fibrils that injure tissue. The fibrils are formed by the aggregation of misfolded, normally soluble proteins. In humans, about 23 different unrelated proteins are known to form amyloid fibrils in vivo. All types of amyloid consist of a major fibrillar protein that defines the type of amyloid (approximately 90%) plus various minor components. Although each type of fibril may be associated with a distinct clinical picture, all share certain physical and pathologic properties, as follows:

* Amorphous eosinophilic appearance on light microscopy after hematoxylin and eosin staining
* Bright green fluorescence observed under polarized light after Congo red staining
* Regular fibrillar structure as observed by electron microscopy
* Beta pleated sheet structure as observed by x-ray diffraction
* Solubility in water and buffers of low ionic strength

* Amyloid

= insoluble fibrous protein aggregations that share specific structual traits
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* Amyloidosis

= abnormal deposition of amyloid proteins in tissues or organs ? cause disease

* Histological Definition
* extracellular proteinaceous deposits exhibiting cross-beta structure due to misfolding of unstable proteins
* stains with Congo-Red & seen under polarised light

* Biophysical Definition
* Any polypeptide which adopts a cross-beta polymerization (in vivo or in vitro)
* Some may fail congo red birefringence test
* Characterised by cross-beta quaterny structure


Recognition of Amyloid
Biochemical Nature of Amyloid
Biochemical Classification of Amyloid
Clinical Classification of Amyloidosis
Pathogenesis of Amyloid
Immunocytic Dyscrasias with Amyloid
Reactive Systemic Amyloidosis
Familial Amyloidosis
Familial Mediteranean Fever
Localised Amyloidosis

* Amyloid deposits limited to single organ or tissue.
* Deposits may produce grossly detachable nodular masses or be evident only on microscopic investigation.
* Nodular deposits of amyloid most often found in lung, larynx, skin, bladder, tongue & region around the eye.
* Frequently there are infiltrates of lymphocytes and plasma cells in the periphery of amyloid masses.
* Some cases consists of AL protein, and may therefore represent a localized form of immunocyte-derived amyloid.

Amyloid of Ageing
Clinical Effect on Spleen
Nodular Distribution
Clinical Effect on Kidney
Clinical Effect on Liver
Clinical Effect on GIT
Diagnosis & Prognosis

Amyloid: Amyloidosis.ppt