Congo red


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Congo red

n.
A brownish-red powder, C32H22N6Na2O6S2, used in medicine and as a dye, indicator, and biological stain.

Congo red

n
(Elements & Compounds) a brownish-red soluble powder, used as a dye, a diagnostic indicator, a biological stain, and a chemical indicator. Formula: C32H22N6O6S2Na2

Con′go red′


n.
a water-soluble powder, C32H22O6N6S2Na2, used chiefly as a dye, biological stain, and chemical indicator.
[1880–85]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.congo red - a red-brown azo dye especially as a chemical pH indicator (congo red is red in basic and blue in acidic solutions)
solution - a homogeneous mixture of two or more substances; frequently (but not necessarily) a liquid solution; "he used a solution of peroxide and water"
acid-base indicator - an indicator that changes color on going from acidic to basic solutions
azo dye - any dye containing one or more azo groups
References in periodicals archive ?
Acetic acid, Acetone, Acid fuschin, Ammonium alum(aluminium ammonium sulphate), Ammonium hydroxide, Ammonia solution, Aniline blue, Basic fuchsin, Bismark brown, Tips for micropipette 100-1000 micro litre, Calcium chloride, Charcoal, Chloroform, Citric acid, Congo red, Copper sulphate, Chloral hydrate, Crystalline phenol, D.
5,20) In a small subset of these patients the casts stain with Congo red, are apple green birefringent, and contain fibrillary material with characteristics most consistent with amyloid fibrils.
16-18) Identification of amyloid is based on three criteria: (1) Congo red binding and green birefringence under polarized light, (19) (2) a fibril structure on electro microscopy, (20) and (3) confirmation of the characteristic cross beta-pleated sheet on x-ray crystallography and infrared spectroscopy.
Apple-green birefringence under polarization after staining with Congo red is diagnostic (figure 2).
7) On a given section, 60% to 80% of vacuolated muscle fibers contain amyloid material; a fluorescence-enhanced Congo red technique is usually required to visualize the amyloid when present in small amounts.
The vascular media was thickened; however, there was no evidence of amyloid deposition on Congo red staining.
11] In our patient, no evidence of amyloid deposits was noted, either morphologically or on Congo red staining.
Sections stained with Congo red dye demonstrated the characteristic yellow and apple-green birefringence, and the lesion had the beta-pleated sheet structure and antiparallel conformation by low-angle x-ray diffraction, typical of amyloidosis.
Four-micrometer-thick, formalin-fixed, paraffin-embedded tissue sections were stained with hematoxylin-eosin, periodic acid-Schiff, Giemsa, Congo red, and crystal violet for light microscopic examination.
Congo red was introduced in Germany in 1885 as the first economically lucrative direct textile dye.
Stains for keratin, HMB-45, leukocyte common antigen, L26, CD3, periodic acid-Schiff with diastase, smooth muscle and muscle-specific actin, S100, Congo red, and [Lambda] light chain were all negative.
More than 100 years after its discovery, the Congo red histologic stain is still of fundamental importance in the laboratory.