Congo red


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Con·go red

(kong'gō red), [C.I. 22120]
An acid direct cotton dye, it is absorbed by amyloid and induces green fluorescence to amyloid in polarized light; used as a laboratory aid in the diagnosis of amyloidosis, as a histologic stain, and as an indicator (pH 3, blue-violet, to pH 5, red) in testing for free hydrochloric acid in gastric contents. See: Bennhold Congo red stain.

Congo red

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

Con·go red

(kong'gō red)
[CI 22120] An acid direct cotton dye, used as an indicator (pH 3.0, blue-violet, to pH 5.0, red) in testing for free hydrochloric acid in gastric contents; the dye is absorbed by amyloid and induces green fluorescence to amyloid in polarized light; used as a laboratory aid in the diagnosis of amyloidosis and as a histologic stain.

Congo red

a synthetic dye, a derivative of benzidine and naphthionic acid. It is used for differential staining of elastic fibers for microscopic examination. Amyloid is stained a light orange-red with Congo red and exhibits apple green birefringence under polarized light. Amyloid in cats stains poorly. Congo red undergoes a change in hue with acidity and thus can be used as an indicator of pH, turning red in the presence of alkalis (bases) and blue when exposed to acids.

Congo red test
a laboratory test used in the diagnosis of amyloidosis, based on measuring the amount of injected dye that is removed by amyloid in the tissues of the human patient. Not now commonly used.
References in periodicals archive ?
Congo red, thioflavins T and S, and stain for amyloid-P component are all negative in this condition.
12] Ewer & Pick alleged that the Congo red dye should be in the public domain because one of their chemists had found an alternative way to synthesize the dye.
Congo Red stained 5 beaks, but none of the marked individuals produced clear positive marks (Table 4), either because the stained area was too diffuse or because the increments around the mark were not clear enough to be counted.
Factors affecting haemolysin production and Congo red binding in Salmonella enterica serovar Typhimurium DT 98.
085 g (Table 3) is measured via congo red test as described above.
show reactivity with silver stain, and have no affinity for Congo red dye, similar to the KW lesions of diabetic nephropathy.
Because oseltamivir phosphate (Figure 1) possesses amine groups, the protonated form may act as a cationic site for anionic dyes such as Congo red and bromochlorophenol blue to produce colored ion-pairing complexes.
Photodegeneration of Congo Red catalyzed by nanosized Ti[O.
Christensen's tube method and congo red agar plate method, can both yield inconclusive and/or intermediate results.
Tissue diagnosis for amyloidosis is made by demonstration of amyloid protein on Congo red stain, where it shows green birefringence under a polarizing microscope.
rhizogenese were isolated, the results showed isolates all were: Gram-negative, catalase-positive, capable of growth on YMB medium containing 3% NaCl, were capable of absorbing Congo red in medium with this test R.