Amyloid and Neuro-Opthalmology

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Identifier Amyloid_and_Neuro-Opthalmology
Title Amyloid and Neuro-Opthalmology
Subject Pathology; Metabolic Diseases; Neurodegenerative Diseases
Creator Andrew G. Lee, MD, Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, TX; Professor of Ophthalmology, Weill Cornell Medicine; Jared Alexander, Baylor College of Medicine Class of 2021
Description Dr. Lee lectures medical students on amyloid.
Transcript So today we're just gonna talk a little bit about amyloid. Amyloid is very weird stuff and a lot of things can become what we call amyloid. So over 30 different proteins now, maybe more, have been identified that can become the amorphous extracellular material which we call amyloid. Under normal conditions, proteins as you know, assume certain folding patterns that allow them to do their job. This post-translational conformational change is intrinsic to the shape and configuration of the protein. When the protein is digested and broken down into little pieces by proteinases those are normally recycled in the system. And those oligomers are little tiny pieces and these oligo-peptides are normally soluble and can move around and then be recycled or made into other stuff. However, in amyloid, the oligo-peptides start to orient and have intra-peptide bonding that creates a sheet. Rather than assuming an alpha helical pattern they assume a beta pleated, and in this case, anti-parallel configuration that will convert the soluble oligo-peptide into an insoluble substance. Once that insoluble substance appears in the tissue, that amorphous extracellular material is what we call amyloid. So if it deposits in your cornea, you might get a corneal opacity. If it deposits in your brain you might get a neurodegenerative disease. If it deposits in the blood vessel, the blood vessel can become friable and bleed. And those different types of amyloid can affect us in neuro-ophthalmology. So we have cerebral amyloid and that can deposit in your brain and cause neurodegenerative disease. We've got an amyloid angiopathy which causes the blood vessel to be friable and causes intracranial hemorrhages. And then we've got amyloid related angiitis, amyloid beta related angiitis. Which means an inflammation angiitis related to an attack, an autoimmune attack, on the amyloid itself. So the amyloid itself is causing a CNS angiitis. So these are the ways that it comes to us as primary CNS angiitis, uh, related to amyloid. When we test for amyloid we have to have special stains because it's extracellular. So the things that we are doing for extracellular amyloid testing are special stains called congo red. And amyloid demonstrates a unique property under polarized light, it demonstrates birefringence. So we can see apple green birefringence under polarized light for amyloid. And the reason it's important to know that is because the standard stains H&E will not detect the amyloid unless we're actually looking for the amyloid. And so that normally means we have to have a biopsy. So the amyloid proteins that we have to worry about can arise from the light chain production, which is amyloid light chain, AL. So if you have light chain overproduction those form the basis of the oligopeptides that become the beta pleated insoluble sheet. You can have just the amyloid protein, AA, or you can have genetic problems in the transthyretin that can lead to predisposition and production of the protein that leads to the final common pathway, which is the production of the extracellular amorphous amyloid. These are less common. And then we have the cerebral amyloid and cerebral amyloid angiopathy. So amyloid is kind of a final common pathway by which proteins self aggregate into an insoluble material that deposits in tissue, whether it's your kidney, your brain, or your eye, that extracellular deposition is what causes the disruption. We need specialized stains to find it, and it can come to us in neuro-ophthalmology as deposition itself, bleeding from amyloid angiopathy, or an unusual condition called amyloid beta related angiitis.
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Date 2019-02
Type Image/MovingImage
Format video/mp4
Rights Management Copyright 2019. For further information regarding the rights to this collection, please visit:
Holding Institution Spencer S. Eccles Health Sciences Library, University of Utah, 10 N 1900 E, SLC, UT 84112-5890
Collection Neuro-ophthalmology Virtual Education Library: NOVEL
Language eng
ARK ark:/87278/s6h464dv
Setname ehsl_novel_lee
Date Created 2019-03-01
Date Modified 2020-01-13
ID 1403663
Reference URL
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