ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
Amyloid, also called BETA AMYLOID PROTEIN (the standard abbreviation is AP), is a PEPTIDE of about 4,000 molecular weight made of between 40 and 42 AMINO ACIDS. It forms part of a larger PROTEIN known as BETA AMYLOID PRECURSOR PROTEIN (abbreviated as APP). Amyloid can be visualized by histological (see HISTOLOGY) stains such as Congo red and thioflavine S, or by IMMUNOHISTOCHEMISTRY. Amyloid is water-insoluble, self-aggregating, and resistant to further degradation. The function of amyloid is not exactly clear, but it is a MEMBRANE protein thought to be involved in the inhibition of PROTEOLYSIS or possibly in CELL growth or adhesion. It is the main component of the neuritic (see NEURITE) or senile PLAQUES seen in ALZHEIMER'S DEMENTIA (and indeed in the brains of other patients groups; see for example DOWN SYNDROME). Although amyloid-containing plaques are neuropatho logical hallmarks of Alzheimer's dementia, how they lead to typical neuronal loss and dementia is not well understood.
Proteins in plasma and urine
Martin Andrew Crook in Clinical Biochemistry & Metabolic Medicine, 2013
Amyloid diseases are secondary protein structure diseases in which insoluble protein fibrils accumulate extracellularly. At least 20 different types of fibrils have been described in human amyloidosis, each with a different clinical picture. All types of tissue amyloid consist of a major fibrillar protein that defines their type. All amyloid types show certain features: soluble in water and in buffers of low ionic strength,amorphous eosinophilic appearance on light microscopy after haematoxylin and eosin staining,green fluorescence seen under polarized light afterCongo red staining,regular fibrillar structure as observed by electron microscopy,X-ray diffraction shows β-pleated sheet structure.
The Occurrence of Protein-AA Specific Antibodies in Experimentally Induced Murine Reactive Amyloidosis
Gilles Grateau, Robert A. Kyle, Martha Skinner in Amyloid and Amyloidosis, 2004
Producing a hybridoma, B11, secreting AA amyloid specific antibodies, by using splenocytes from an animal suffering from reactive AA amyloidosis, proofs that there exists autoantibodies directed against AA amyloid or protein AA in mice. This study is still preliminary and absorption tests of antibody specificity are still lacking. But since immunoreactivity is restricted to amyloid deposits and the unspecific binding is low, we are convinced that the antibody is amyloid specific rather than SAA specific. The presence of amyloid specific autoantibodies may contribute to the natural resolution of amyloid deposits, occurring when inflammation ceases. It does also support the hypothesis that amyloid deposition may trigger an adaptive immune response. We also present results indicating the possibility to decrease amyloid deposition by passive immunization with amyloid specific antibodies, in reactive amyloidosis in mice. It is a small study with a considerable falling off, 20%, in both the experimental and control group. The non planned deaths of animals took place late in the experiment and were probable due to repeated interventions. The decrease in amyloid deposition may be caused by a structural mechanism. Antibodies binding to the amyloid and interferes with the fibrillar structure, preventing growth of fibrils. Another mechanism of action may be that binding of antibody triggers the animal’s immune response and macrophages are recruited to resolve the amyloid. However, it is not excluded that antibodies act by binding to circulating SAA or protein AA.
AL amyloidosis presenting as inflammatory polyarthritis: a case report
Published in Modern Rheumatology Case Reports, 2021
Muhammad Shoaib Momen Majumder, Shamim Ahmed, Md. Nahiduzzamane Shazzad, Mohammad Mamun Khan, Syed Atiqul Haq, Mohammed Kamal, Md. Sohrab Alam, Johannes J. Rasker
Amyloid protein can deposit in various organs/tissues. Clinical features depend upon the type of amyloid protein and organ/tissue where deposited. Systemic AL amyloidosis can involve any organ except the central nervous system [2]. An updated definition of organ involvement in AL amyloidosis has been made in a meeting of the International Society of Amyloidosis held in 2010 in Rome [19,20]. Amyloid arthropathy is a relatively uncommon presentation (approximately 5%) of systemic amyloidosis [21]. It is low grade, subacute, progressive, and symmetric with a predilection for shoulders, knees, wrists, MCPs, PIPs, and less commonly elbows and hips. There may be pain, swelling, and morning stiffness that may mimic chronic inflammatory arthropathies [1]. Though amyloid arthropathy is rather uncommon as a presenting feature of amyloidosis, when present, it is regarded as a disease-specific finding in AL amyloidosis [21]. It may also cause nodular hypertrophy of synovium due to amyloid deposits. Rarely erosive arthritis has been reported in patients with AL amyloidosis coexisting with monoclonal gammopathy of uncertain significance [22]. Swelling may be particularly prominent around glenohumeral joints resulting in a characteristic “shoulder pad” sign. It is pathognomonic for AL amyloidosis [23].
Lacrimal gland extranodal marginal zone B-cell lymphoma in the presence of amyloidosis
Published in Orbit, 2022
Chung Shen Chean, Vishakha Sovani, Ali Boden, Christopher Knapp
Amyloidosis is a disorder characterised by extracellular deposition of insoluble fibrils with a β-sheet structure derived from aggregation of misfolded proteins. More than 20 types of amyloid proteins have been identified in various human organs.1 The most common and severe form of systemic amyloidosis is the amyloid light chain (AL) amyloidosis.5 The protein consists of filaments of a monoclonal immunoglobulin light chain, typically originating from a small plasma cell clone with isolated monoclonal paraproteinaemia or asymptomatic myeloma. Its association with systemic myeloma or B-cell lymphoproliferative disorders is uncommon.2,5 Laboratory findings include elevated levels of serum immunoglobulin light chain kappa or lambda and Bence Jones protein in the urine.2,9 Diagnosis of amyloidosis is confirmed by staining a biopsy specimen with Congo red stain, which gives a characteristic apple-green birefringent pattern under polarised light.4 Immunocytochemistry can also be useful in identifying the amyloid protein.10
Tracheobronchial amyloidosis: A report of two cases and literature review
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2018
Sultan Qanash, Nadir Kharma, Stephen Corne
Amyloid is a rare disease resulting from extracellular tissue deposition of abnormal protein. It may be systemic or localized. Amyloid is classified by the type of proteinacious material that is deposited, since this determines organ involvement. Although up to 15 types of systemic amyloid have been described, the four major types include: Amyloid light chain (AL), Apolipoprotein serum amyloid (AA), beta2-microglobulin (β2-m) amyloid, and transthyretin amyloidosis (ATTR).1 Clinical involvement of the lung is rare in all except the amyloid light chain (AL) amyloidosis variant. In AL systemic amyloid, bone marrow plasma cells secrete excessive quantities of monoclonal light chains, which are deposited widely, although clinical involvement may be limited to specific organs. In systemic AL, five main types of respiratory system involvement have been described: 1) interstitial lung disease; 2) adenopathy; 3) nodular disease; 4) pleural; and 5) diaphragmatic.2,3
Related Knowledge Centers
- Amyloidosis
- Beta Sheet
- Congo Red
- Physiology
- Protein
- Protein Secondary Structure
- Staining
- Body
- Protein Structure
- Proteinopathy