He was looking for textile dyes that did not require a mordant step. This technique is relatively subjective and a known fibrillar sample should be used as a control. Münchener Medizinische Wochenschrifte 1922. Rinse in distilled water for 10 minutes. 2001 Feb;125(2):250-2. 1. Congo red was formerly used to dye cotton but has been superseded by dyes more resistant to light and to washing. If the polarizers are crossed at a 90 angle to each other, the background of the sample will turn black. 5. All rights reserved. However, the use of Congo red has long been abandoned, primarily because of its carcinogenic properties.[1]. Congo red staining detects amyloid deposits in brain tissue of amyloid precursor protein transgenic mice and human Alzheimer's tissue. The dye can also be used in flow cytometry experiments for the detection of Acanthamoeba, Naegleria and other amoebal cysts. 9. The reason for this is that the Congo red dye used in the stain is highly selective for amyloid deposits, which can lead to … This condition of deposition of amyloid in tissues is known as Amyloidosis. PubMed PMID: 11175644. Air-dry the sample and analyze under polarized light. This attachment is achieved by the non-polar hydrogen bonds formed between the Congo red and amyloid deposit. 2014 Aug;45(8):1766-72. The ability to detect amyloid deposits in human tissue is the critical first step in making a diagnosis of amyloidosis. 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. Sorry for the convenience. … Add 5–10µL of protein solution to the cuvette and incubate for 30 min at room temperature. Congo Red Stain * Component test codes cannot be used to order tests. Deparaffinize and bring sections to distilled water. To have a better experience, please upgrade to Microsoft Edge, Google Chrome, or Firefox. https://www.ncbi.nlm.nih.gov/pubmed/11175644, https://www.ncbi.nlm.nih.gov/pubmed/24935061. Apple-green birefringence of Congo red stained preparations under polarized light is indicative of the presence of amyloid fibrils. To use this sample for the microscopic analysis, transfer the protein + Congo Red solution from the cuvette to a centrifuge tube, centrifuge at 12,000–14,000 rpm to pellet the fibrils, wash the fibrils with water, resuspend the fibrils in a small amount of water, and place on a glass microscope slide. Figure 3: Congo red stain, fluorescence microscopy with Texas red filter, Steensma DP. Congo Red can be used straight from the manufacturer or can be recrystallized from 50% EtOH: 50% DDI water prior to use. Congo Red spectrophotometric assay is more objective, less prone to misinterpretation, and can be easily combined with the microscopic analysis. © 2020 LaboratoryInfo.com. Staining with Congo Red (CR) is a qualitative method used for the identification of amyloids in vitro and in tissue sections. Stain in congo red working solution for 10 minutes. Please select your favorite tests to print a custom catalog. Congo red is water-soluble, yielding a red colloidal solution; its solubility is greater in organic solvents. 4. Procedures for Congo Red birefringence assay: 1. Counterstain with Meyer’s Hematoxylin for 30 seconds. Use cold pack for transport. Bennhold, H. Eine spezifische amyloidfärbung mit Kongorot [Specific staining of amyloid with Congo red]. Procedures for Congo Red birefringence assay: 1. Furthermore, Congo red may also be used to induce ex… 3. All rights reserved. Congo red dye forms nonpolar hydrogen bonds with amyloid and red to apple green birefringence occurs when viewed by polarized light due to alignment of dye molecules on the lineraly arranged amyloid fibrils. ©2020 Arkana Laboratories. Although these aggregates are present under various sizes and shapes, the "ribbon-like micelles" of a few molecules seem to be the predominant form (even if the "micelle" term is not an entirely appropriate name for it). Additionally, Congo red … Griesbach, H. Weitere untersuchungen über azofarbstoffe behufs tinction menschlicher und thierischer gewebe [Further studies of azo dyestuffs as a stain of human and animal tissues]. Any bright spots that appear are a result of birefringence (the sample bends the light in such a way that it can pass through the upper polarizer to reach your eye).The detection of yellow/green birefringence is considered a positive result for the presence of amyloid.The absence of such birefringence is a negativeresult. Amyloidosis is a rare disease characterized by the deposition of insoluble misfolded proteins in various tissues and organs. If the polarizersare aligned, the material stained with Congo Red will appear reddish pink (the affinity for CongoRed is known as congophilia). 12701 Commonwealth Dr., Suite 9 Deparaffinize and bring sections to distilled water. Mathematically subtract the Congo Red spectrum from the protein+ Congo Red spectrum. Rinse in tap water. Zero a UV–Vis spectrophotometer between 400 and700 nm at room temperature with a sample of 1mL phosphate buffer in a disposable cuvette. 3. Counterstain with Meyer’s Hematoxylin for 30 seconds. Many things other than amyloid exhibit birefringence; buffer salts (phosphate and urea) are inherently birefringent and appear as intense white birefringence, hair or other fibers exhibit birefringence but are often multicolored. J Belge de Neurologie et de Psychiatrie 1927. all about medical laboratories : microbiology, biochemistry, hematology, histopathology, virology, bacteriology, mycology and parasitology, Hematoxylin and Eosin staining : Principle, Procedure and Interpretation, Papanicolaou (PAP) Staining : Introduction, Principle, Procedure and Interpretation, Gomori’s Silver Impregnation Staining Technique for Reticulin Fibers, Warthin Starry Staining Technique For Spirochetes, Wade-Fite Staining Technique For Mycobacterium leprae, What is Nutrient Agar – Composition, How to Prepare and Uses, Difference Between Phenotype and Genotype, Difference between Biotic and Abiotic factors, Difference between Plant cell and Animal cell. All Rights Reserved. It is still used in histology to stain tissues for microscopic examination, and to serve as an … Fix slides in formalin (under hood) for at least. Place coverslips on slides using permount solution. 69:1537–1538. AGFA marketed the dye under the name "Congo red", a catchy name in Germany at the time of the 1884 Berlin West Africa Conference, an important event in the Colonisation of Africa. At this stage, a red precipitate may become visible. The company was not interested in this bright red color, so he filed the patent under his own name and sold it to the AGFA company of Berlin. Clement CG, Truong LD. Receive weekly updates on NeoGenomics tests, research, events, and publications. The reason for this is that the Congo red dye used in the stain is highly selective for amyloid deposits, which can lead to amyloidosis and also alzheimers. 8. Students can find additional information in the Undergraduate Student Guide and Graduate & Professional Student Guide. Divry, P. Etude histochimique des plaques seniles [Histochemical study of senile plaques]. Prepare in staining dishes fresh 200 mlsolutions of: alkaline 80% ETOH/saturated NaCl: add 2 ml of 1% NaOH to 198 ml 80% ETOH/saturated NaCl and filter. Put in 2 separate 95% alcohol solutions (10 dips in each until slides are completely bathed), blot bottom of rack with paper towel to remove excess solution before proceeding to the next rinse).

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