Apple-green birefringence of Congo red stained preparations under polarized light is indicative of the presence of amyloid fibrils. Amyloid refers to the abnormal, fibrous, extracellular proteinaceous deposits found in organs such as liver, kidneys, spleen etc. Special stain. David P. Steensma, MD, offers readers a fascinating history of the Congo red stain (see … Congo red stain is the gold standard for the demonstration of amyloid in tissue sections. It is still used in histology to stain tissues for microscopic examination, and to serve as an … Place slides at one end of large slide dish and run tap water on opposite end of dish for, Place in alkaline 80% ETOH/saturated NaCl for. 2. Congo red histological staining technique is the gold standard technique for the diagnosis of amyloidosis. Congo Red can be used straight from the manufacturer or can be recrystallized from 50% EtOH: 50% DDI water prior to use. https://www.ncbi.nlm.nih.gov/pubmed/11175644, https://www.ncbi.nlm.nih.gov/pubmed/24935061. For cases with positive Congo red staining, immunohistochemical stains for amyloid A, amyloid P and immunoglobulin light chains are available for further evaluation of the amyloid subtype, if clinically indicated. Dip in ammonia water for 30 seconds until sections turn blue. [O-]S(=O)(=O)c5cc(/N=N/c1ccc(cc1)c4ccc(/N=N/c3cc(c2ccccc2c3N)S([O-])(=O)=O)cc4)c(N)c6c5cccc6, Except where otherwise noted, data are given for materials in their, Klaus Hunger, Peter Mischke, Wolfgang Rieper, Roderich Raue, Klaus Kunde, Aloys Engel: "Azo Dyes" in, Gerald Booth "Naphthalene Derivatives" in, 10.1043/0003-9985(2001)125<0250:CR>2.0.CO;2, Ullmann's Encyclopedia of Industrial Chemistry, https://en.wikipedia.org/w/index.php?title=Congo_red&oldid=983774478, Articles with dead external links from August 2017, Articles with permanently dead external links, Pages using collapsible list with both background and text-align in titlestyle, Articles containing unverified chemical infoboxes, Creative Commons Attribution-ShareAlike License, This page was last edited on 16 October 2020, at 05:02. Divry, P. Etude histochimique des plaques seniles [Histochemical study of senile plaques]. Congo Red birefringence assay was developed for the examination of in vivo amyloid and was later applied in the examination of in vitro samples. Fort Myers, FL 33913 [https://www.ncbi.nlm.nih.gov/pubmed/24935061]. … Fix slides in formalin (under hood) for at least. © 2020 LaboratoryInfo.com. More recently, Clement and Truong have shown how fluorescence microscopy using a Texas red filter may enhance the identification of amyloid deposits in Congo red-stained tissue sections, especially when deposits are small. Since this color change is an approximate inverse of that of litmus, it can be used with litmus paper in a simple parlor trick: add a drop or two of Congo red to both an acid solution and a base solution. Additionally, Congo red … 4. Zero a UVâVis spectrophotometer between 400 and700 nm at room temperature with a sample of 1mL phosphate buffer in a disposable cuvette. Procedures for Congo Red birefringence assay: 1. The dye can also be used in flow cytometry experiments for the detection of Acanthamoeba, Naegleria and other amoebal cysts. David P. Steensma, MD, offers readers a fascinating history of the Congo red stain (see references), which still remains the most widely used and cost-effective way to identify amyloid deposits in pathology specimens. The proposed mechanisms suggest hydrophobic interactions between the aromatic rings of the dye molecules, leading to a π–π stacking phenomenon. If you delete your browser cookies, you will need to rebuild your test list. In the following years, for the same reason, other dyes were marketed using the "Congo" name: Congo rubine, Congo corinth, brilliant Congo, Congo orange, Congo brown, and Congo blue. It is an azo dye. Due to a color change from blue to red at pH 3.0–5.2, Congo red can be used as a pH indicator. Squeeze two slides together firmly with thumb and index finger. Congo red is water-soluble, yielding a red colloidal solution; its solubility is greater in organic solvents. Congo Red is an indicator dye that is blue-violet at pH 3.0 and red at pH 5.0. Place specimen from syringe on slide and place second labeled slide on top (at 90° angle and face to face with bottom slide). RESULTS: Histopathologic findings demonstrated noninflammatory, fibrous connective tissue in 31 of 35 … Deparaffinize and bring sections to distilled water. © Boston University.  Once of economic significance, Congo red has fallen into disuse as have all benzidine-derived dyes, owing to their carcinogenic activity. However, the use of Congo red has long been abandoned, primarily because of its carcinogenic properties.. The ability to detect amyloid deposits in human tissue is the critical first step in making a diagnosis of amyloidosis. All rights reserved. As you browse our test menu, and you see your preferred test, simply select the Add to Favorites button. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the … Clement CG, Truong LD. The main special stain used for amyloid detection is Congo Red. Prepare the staining solution: prepare a solution of 80% EtOH: 20% DDI water and add a saturating amount of NaCl. Air dry slides for 10 min. 69:1537–1538. Münchener Medizinische Wochenschrifte 1922. Design by. In histology and microscopy, Congo red is used for staining in amyloidosis, and for the cell walls of plants and fungi, and for the outer membrane of Gram-negative bacteria. NOTE: This is a cookie-based feature. Amyloidosis is a rare disease characterized by the deposition of insoluble misfolded proteins in various tissues and organs. 3. PubMed PMID: 11175644. Figure 1: Congo red stain positive for amyloid, light microscopy Furthermore, Congo red may also be used to induce ex… Congo red was first synthesized in 1883 by Paul Böttiger, who had been employed at Friedrich Bayer Company in Elberfeld, Germany. Hum Pathol. Add 5ÂµL of the Congo Red solution to the phosphatebuffer, scan between 400 and 700 nm and recordthe spectrum. Stir this solution for a few minutes and filter away the excess NaCl. More recently, Clement and Truong have shown how fluorescence microscopy using a Texas red filter may enhance the identification of amyloid deposits in Congo red-stained tissue sections, especially when deposits are small. 5. Remove top slide up and off bottom slide (DO NOT REMOVE AS FOR A BLOOD SMEAR. Congophilic amyloid in blood vessels is called cerebral amyloid angiopathy (CAA). Congo red has a propensity to aggregate in aqueous and organic solutions. In histology and microscopy, Congo red is used for staining in amyloidosis, and for the cell walls of plants and fungi, and for the outer membrane of Gram-negative bacteria.Apple-green birefringence of Congo red stained preparations under polarized light is indicative of the presence of amyloid fibrils. Deparaffinize and bring sections to distilled water. Congo Red is the sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid; a diazo dye that is red in alkaline solution and blue in acid solution and used especially as an indicator and as a biological stain. The ability to detect amyloid deposits in human tissue is the critical first step in making a diagnosis of amyloidosis. An evaluation of Congo red fluorescence for the diagnosis of amyloidosis. Â© Copyright Reserved, This site is powered by Sino Biological Inc. Fourier transform infrared (FTIR) spectroscopy assay, Chromatin immunoprecipitation (ChIP) protocol. In histology and microscopy, Congo red is used for staining in amyloidosis, and for the cell walls of plants and fungi, and for the outer membrane of Gram-negative bacteria. Visit Back2BU for the latest updates and information on BU's response to COVID-19. Add a saturating amount of Congo Red, stir, and filter to obtain thefinal working solution. Figure 3: Congo red stain, fluorescence microscopy with Texas red filter, Steensma DP.
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