Amyloid is defined as in vivo deposited material distinguished by fibrillar electron micrographic appearance, amorphous eosinophilic appearance on hematoxylin and eosin staining (see the first image below), beta pleated sheet structure as observed by x-ray diffraction pattern, apple-green birefringence on Congo Red histological staining (see the second image below), and solubility in water and buffers of low ionic strength. All types of amyloid consist of a major fibrillar protein that defines the type of amyloid.[1, 2]
Amorphous eosinophilic interstitial amyloid observed on a renal biopsy. 
Congo Red staining of a cardiac biopsy specimen containing amyloid, viewed under polarized light. Amyloidosis is a clinical disorder caused by extracellular and or intracellular deposition of insoluble abnormal amyloid fibrils that alter the normal function of tissues. Approximately 10% of amyloidosis depots consist of components such as glycosaminoglycans (GAGs), apolipoprotein E (apoE), and serum amyloid P (SAP) component, while 90% of the depots consist of the amyloid fibrils that are formed by the aggregation of misfolded proteins. These proteins either arise from proteins expressed by cells at the deposition site (localized) or precipitate systemically after production at a local site (systemic).[3] In humans, about 23 different unrelated proteins are known to form amyloid fibrils in vivo.[4] Many mechanisms of protein function contribute to amyloidogenesis, including "nonphysiologic proteolysis, defective physiologic proteolysis, mutations involving changes in thermodynamic or kinetic properties, and pathways that are yet to be defined."[4]
Amorphous eosinophilic interstitial amyloid observed on a renal biopsy. Congo Red staining of a cardiac biopsy specimen containing amyloid, viewed under polarized light. Amyloidosis is a clinical disorder caused by extracellular and or intracellular deposition of insoluble abnormal amyloid fibrils that alter the normal function of tissues. Approximately 10% of amyloidosis depots consist of components such as glycosaminoglycans (GAGs), apolipoprotein E (apoE), and serum amyloid P (SAP) component, while 90% of the depots consist of the amyloid fibrils that are formed by the aggregation of misfolded proteins. These proteins either arise from proteins expressed by cells at the deposition site (localized) or precipitate systemically after production at a local site (systemic).[3] In humans, about 23 different unrelated proteins are known to form amyloid fibrils in vivo.[4] Many mechanisms of protein function contribute to amyloidogenesis, including "nonphysiologic proteolysis, defective physiologic proteolysis, mutations involving changes in thermodynamic or kinetic properties, and pathways that are yet to be defined."[4] 
ليست هناك تعليقات:
إرسال تعليق