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Topic: Amyloid


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  Amyloid
Polyneuropathy: Occurs in 20% of patients with light chain amyloid
Protein forming the amyloid is sometimes identifiable by immunocytochemistry
Amyloid deposition in nerve connective tissue and near vessels
www.neuro.wustl.edu /neuromuscular/nother/amyloid.htm   (450 words)

  
 Amyloid Plaques   (Site not responding. Last check: 2007-11-06)
The formation of amyloid plaques and neurofibrillary tangles are thought to contribute to the degradation of the neurons (nerve cells) in the brain and the subsequent symptoms of Alzheimer's disease.
One of the hallmarks of Alzheimer's disease is the accumulation of amyloid plaques between nerve cells (neurons) in the brain.
Amyloid is a general term for protein fragments that the body produces normally.
www.ahaf.org /alzdis/about/AmyloidPlaques.htm   (169 words)

  
 Amyloid Plaque: 2001
The growth of cored plaque from a small plaque with one microglial cell with an amyloid star and a few dystrophic neurites to a large plaque formed by several dozen microglial cells seen in old mice is the effect of attraction and activation of microglial cells residing outside of the plaque perimeter.
The number of amyloid deposits measured by Congo Red birefringence was increased in the double ACT/amyloid precursor protein (APP) transgenic mice compared with transgenic mice that only expressed APP, particularly in the hippocampus where ACT expression was highest, and the increase was preceded by elevated total amyloid beta-peptide levels at an early age.
Amyloid plaques and neurofibrillary tangles are prominent lesions in the aging brain and they may be responsible for cell death in Alzheimer's disease.
lansbury.bwh.harvard.edu /Literature/Review/amyloid_plaque_2001.htm   (14720 words)

  
 Amyloid - Wikipedia, the free encyclopedia
To be specific, amyloid deposits are extracellular, thioflavin-positive, and exhibit apple-green birefringence when stained with congo red.
The phenotypes of genetically-transmitted amyloid diseases are often inherited in an autosomal dominant fashion.
It should be noted that, in almost all of the organ-specific pathologies, there is significant debate as to whether the amyloid plaques are the causal agent of the disease or instead a symptom downstream of a common ideopathic agent.
en.wikipedia.org /wiki/Amyloid   (742 words)

  
 DRL Islet Amyloid Laboratory   (Site not responding. Last check: 2007-11-06)
Amyloid is the name given to an insoluble mass of fibrillar protein that is deposited in several pathological conditions such as in the brain in Alzheimer's disease, in pancreatic islets in Type 2 diabetes and in other organs in chronic arthritis.
In Type 2 diabetes, amyloid deposition occurs over decades and is associated with a progressive decline in insulin secretion and destruction of islet beta cells in the course of the disease; less than 30% of insulin secreting cells remain in islets severely affected by amyloid.
Amyloid fibrils and peptides are identified by quantitative immunoelectron microscopy.
www.drl.ox.ac.uk /amyloid.html   (647 words)

  
 The Amyloid Proteins of Alzheimer's Disease as Potential Targets for Drug Therapy
Amyloid is a term that refers to a class of proteins that share several properties.
Amyloid proteins with amino acid sequences that are distinct from those of Alzheimer's disease accumulate in numerous diseases.
The second mechanism proposed for amyloid formation is the occurrence of a posttranslational modification of the precursor protein that renders it amyloidogenic.
www.dmso.org /articles/alzheimers/alzheim1.htm   (3242 words)

  
 Cerebral amyloid angiopathy
Amyloid protein resembles a starch and is deposited in tissues during the course of certain chronic diseases.
The cause of amyloid deposits in blood vessels in the brain in sporadic CAA is not known.
The systemic theory suggests that amyloid beta protein in the blood stream is deposited in blood vessels in the brain, causing weakness in the blood vessel wall and breakdown in the blood-brain barrier.
www.healthatoz.com /healthatoz/Atoz/ency/cerebral_amyloid_angiopathy.jsp   (2069 words)

  
 Amyloid clearly implicated in Alzheimer's disease -- Berger 317 (7151): 102 -- BMJ   (Site not responding. Last check: 2007-11-06)
One of the reasons that the precise role of fibrillar B amyloid has remained elusive, despite its undeniable presence in the brains of people with Alzheimer's disease, is that none of the experimental mouse models of the disease has exhibited the full range of pathological features found in human Alzheimer's disease.
Transgenic mice that express amyloid precursor protein in the cerebral cortex do not seem to sustain neurological pathology, and little neuronal death occurs when rats are injected with quantities of amyloid similar to that found in an amyloid plaque.
Injections of both soluble B amyloid and the solution used to carry the fibrillar form caused significantly smaller amounts of damage, demonstrating that it is the fibrillar B amyloid that kills neurones and not simply the act of injecting something into the brain.
bmj.bmjjournals.com /cgi/content/full/317/7151/102   (797 words)

  
 Amyloid Protein   (Site not responding. Last check: 2007-11-06)
Amyloid protein is removed from the environment due to uptake by microglia.
Initially, soluble amyloid is secreted from neurons in the center of the environment.
Amyloid fibers are also placed randomly in the domain based on the initial fiber occupancy parameter, p.
www.math.ubc.ca /~ais/website/formulation/amyloid.html   (643 words)

  
 Alzforum: Live Discussions: Now You See Them, Now You Don't: The Amyloid Channel Hypothesis
This antibody could block cytotoxicity of a range of amyloid peptides, strongly suggesting that oligomers were the toxic species, and that the toxic mechanism (or at least a part of it) was common to all the amyloids.
Islet amyloid polypeptide (IAPP, amylin) is a 37-residue amyloidogenic hormone which is cosecreted with insulin from β; cells in the islets of Langerhans in the pancreas.
Amyloid deposits comprising IAPP are found in the islets of patients with type II diabetes and are positively correlated with β cell loss and clinical insulin requirements (Westermark and Wilander, 1978; Butler et al., 2003).
www.alzforum.org /res/for/journal/kagan   (8723 words)

  
 Biophysical Journal: Mechanism of Amyloid Spherulite Formation by Bovine Insulin, The   (Site not responding. Last check: 2007-11-06)
Amyloid fibrils are large polymeric assemblies composed of multiple copies of a single protein.
All amyloid fibrils possess a common underlying structure irrespective of the polypeptide precursor, and all give rise to a "cross-β" x-ray fiber diffraction pattern indicating that the β-strands making up the fibril backbone lie perpendicular to the fibril axis (Sunde and Blake, 1997).
In a recent article, we described the structure of bovine insulin amyloid fibril spherulites formed in the absence of salt (Krebs et al., 2004) and found that the "spherites" observed by Waugh in 1946 are identical in structure to the wide range of spherulites described above.
www.findarticles.com /p/articles/mi_qa3938/is_200503/ai_n13504194   (1223 words)

  
 eMedicine - Amyloid Angiopathy : Article by Jose G Merino, MD   (Site not responding. Last check: 2007-11-06)
Some evidence suggests that the amyloid is produced in the smooth muscle cells of the tunica media as a response to damage of the vessel wall (perhaps by arteriosclerosis or hypertension).
The amyloid protein is a mutant of the cysteine protease inhibitor cystatin C. Severity of angiopathy and fibrinoid necrosis closely correlate with the occurrence of ICH.
The presence of vascular amyloid is a sensitive marker for CAA-related hemorrhage.
www.emedicine.com /neuro/topic628.htm   (3648 words)

  
 HHMI News: Amyloid Fibers Sprout One Step at a Time
Initial efforts to understand amyloid formation compared the process to the formation of the cell's cytoskeleton, - a better understood mechanism known as nucleation-polymerization, in which the cytoskeletal proteins (actin and tubulin) coalesce into long fibers.
Amyloid formation was also associated with the transient accumulation of intermediate molecules that have been implicated in causing disease.
When shorter amyloid segments or monomers are tagged with a fluorescent molecule of a different color and added to the immobilized fiber, researchers can watch the growth of the fiber.
www.hhmi.org /news/weissman4.html   (934 words)

  
 Taylor & Francis Journals: Welcome
Amyloid: the Journal of Protein Folding Disorders is dedicated to the study of all aspects of the protein groups and associated disorders that are classified as the amyloidoses as well as other disorders associated with abnormal protein folding.
Amyloid is recognised as one of the leaders in the publication of the classification of the amyloid proteins and the associated disorders as well as clinical studies of all aspects of the amyloid related neurodegenerative diseases and major clinical studies on the inherited amyloidosis, especially those related to transthyretin.
Amyloid: the Journal of Protein Folding Disorders is the official journal of the International Society of Amyloidosis.
www.tandf.co.uk /journals/titles/13506129.asp   (211 words)

  
 Senile cerebral amyloid angiopathy
Senile cerebral amyloid angiopathy is characterized by deposits of amyloid protein in the walls of the arteries of the brain, which increases the risk of bleeding into the brain (hemorrhagic stroke).
Senile cerebral amyloid angiopathy is a cause of lobar intracerebral hemorrhage (bleeding in a localized area of the brain, a form of stroke) in the elderly.
Amyloid protein is deposited in the arterial walls of the brain, and there are often no deposits elsewhere in the body.
www.healthcentral.com /ency/408/000719.html   (267 words)

  
 Amyloid at opensource encyclopedia   (Site not responding. Last check: 2007-11-06)
Because of its amorphous nature, amyloid can be difficult to see with usual histology stains such as haematoxylin and eosin.
One characteristic of amyloid is that it is birefringent under polarised light.
Amyloid will appear apple-green and yellow, depending on the direction the protein aggregates are orientated.
www.wiki.tatet.com /Amyloidosis.html   (177 words)

  
 The Amyloid Proteins of Alzheimer's Disease as Potential Targets for Drug Therapy
The amyloid deposits associated with myeloma are derived from Bence Jones proteins, the immunoglobulin light chain dimers that are synthesized by the malignant plasma cells in this disease.
While it has not been established that proteolysis of these proteins in vivo is responsible for the amyloid associated with myeloma, it has been shown that the soluble Bence Jones proteins form amyloid in vitro as a result of proteolysis.
Nonetheless if accumulation of beta amyloid protein is at least in part due to increased accumulation of precursor, then modifying gene expression to reduce precursor levels might be expected to reduce the formation of beta amyloid protein.
www.dmso.org /articles/alzheimers/alzheim2.htm   (2983 words)

  
 Why do amyloid diseases strike different tissues?
An analogous disease called familial amyloid cardiomyopathy (FAC), which is caused by deposition of a few variants of TTR in the heart, leads to cardiac dysfunction and ultimately congestive heart failure.
Similarly, misfolded and misassembled amyloid beta proteins are thought to be a major player in Alzheimer's disease, because they can accumulate into the fibrils and plaques that autopsies reveal in the brains of patients with the disease.
Familial amyloid polyneuropathy patients have amyloid plaques in their peripheral neurons, for instance, and familial amyloid cardiomyopathy patients have amyloid plaques in their hearts, whereas CNS selective amyloid patients have deposits in their brains.
www.medicalnewstoday.com /medicalnews.php?newsid=22501   (2270 words)

  
 UpToDate Amyloid cardiomyopathy
Amyloid deposits can occur in a variety of organs, with involvement of the heart, kidney, and liver most often being responsible for morbidity and mortality.
In the two most common forms of amyloidosis, the amyloid protein is composed of monoclonal light chain fragments in AL (primary) amyloidosis, which is a plasma cell dyscrasia, and fragments of serum amyloid A protein in AA (secondary) amyloidosis, which is associated with chronic inflammatory disorders.
This distinction was illustrated in a review of 36 patients with amyloid heart disease: 12 with familial (mostly familial amyloidotic polyneuropathy) and 24 with AL amyloidosis [3].
patients.uptodate.com /topic.asp?file=myoperic/5672   (537 words)

  
 beta Amyloid peptide (ab3698) datasheet   (Site not responding. Last check: 2007-11-06)
The cerebral and vascular plaques associated with Alzheimer's disease are mainly composed of Amyloid beta peptides.
beta Amyloid is derived from cleavage of the Amyloid precursor protein and varies in length from 39 to 43 amino acids.
Transcription factor NF-kappaB is activated in primary neurons by amyloid beta peptides and in neurons surrounding early plaques from patients with Alzheimer disease.
www.abcam.com /?datasheet=3698   (485 words)

  
 C&EN: SCIENCE & TECHNOLOGY - WHAT'S BEHIND AMYLOID DISEASES?   (Site not responding. Last check: 2007-11-06)
For years, most researchers have backed the notion that clumps of long amyloid fibrils located in the brain and other organs are responsible for killing neurons and other cells in patients who have these conditions.
It has taken a while, but the hypothesis that a precursor of the insoluble amyloid fibril may be the more dangerous entity is now gaining ground.
And maybe an amyloid fibril is a default, stable structure.
pubs.acs.org /cen/science/8032/8032sci1.html   (576 words)

  
 A new species of amyloid peptide
These amyloid β-peptides are derived from a large amyloid precursor protein through a series of cleavage events.
Alternatively, amyloid precursor protein can be processed by the enzymes β-secretase and γ-secretase to produce a soluble ectodomain along with the full-length amyloidogenic amyloid β-peptide and the intracellular C-terminal domain.
While the exact pathogenic role of amyloid β-peptide in Alzheimer's disease has not yet been definitely established, accumulating evidence supports the hypothesis that amyloid β-peptide production and deposition in the brain could be a causative event in Alzheimer's disease.
www.eurekalert.org /pub_releases/2004-11/asfb-ans112304.php   (791 words)

  
 Prions
The amyloid fiber is a coil of several fibrils, themselves helical beta sheet of strands perpendicular to a cylindrical axis.
The intense reflection at 4.7 to 4.8 A Ý that dominates the meridional diffraction patterns of amyloid fibrils is derived from the mean separation of the hydrogen-bonded b-strands that are arranged perpendicular to the fibre axis in the cross-b structure (Figure 2).
It is also possible that the diameters of the protofilaments (and therefore their centre-to-centre spacing) may vary because of the need to accommodate differently sized loops linking the b-structure core, and/or to allow for some variation in the lengths of the b-strands dependent on the nature of the precursor.
www.mad-cow.org /~tom/structural_studies.html   (6528 words)

  
 VASCULITIS, AMYLOIDOSIS, IMMUNODEFICIENCY
Amyloid is a class of insoluble, homogeneous, eosinophilic ("hyaline") substances that accumulate in extracellular spaces.
Amyloid arthropathy, mostly limited to the joints and flexor retinaculum, is a problem in kidney-failure patients who have been on hemodialysis for years.
Amyloid is deposited first in the perisinusoidal spaces, and this appears to crunch the hepatocytes after a while.
www.pathguy.com /lectures/imm-iii.htm   (8204 words)

  
 Primary amyloid tumour of the breast: a case report -- Deolekar et al. 55 (8): 634 -- Journal of Clinical Pathology
Primary amyloid tumour of the breast: a case report -- Deolekar et al.
The AA amyloid was associated with a carcinoma in one patient
Localised primary amyloid tumour associated with osseous metaplasia presenting as bilateral breast masses, cytologic and radiologic features.
jcp.bmjjournals.com /cgi/content/full/55/8/634   (915 words)

  
 ScienceDaily: A New Species Of Amyloid Peptide   (Site not responding. Last check: 2007-11-06)
These amyloid and#946;-peptides are derived from a large amyloid precursor protein through a series of cleavage events.
Alternatively, amyloid precursor protein can be processed by the enzymes and#946;-secretase and and#947;-secretase to produce a soluble ectodomain along with the full-length amyloidogenic amyloid and#946;-peptide and the intracellular C-terminal domain.
While the exact pathogenic role of amyloid and#946;-peptide in Alzheimer's disease has not yet been definitely established, accumulating evidence supports the hypothesis that amyloid and#946;-peptide production and deposition in the brain could be a causative event in Alzheimer's disease.
www.sciencedaily.com /releases/2004/11/041129111135.htm   (1101 words)

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