Histochemische und polarisationsoptische Untersuchungen am Amyloid

Diezel, Paul Bernd; Pfleiderer, Albrecht

doi:10.1007/bf02438761

Cited by 35 publications

(9 citation statements)

References 17 publications

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“…We showed that the birefringence of orientated Congo red varied with wavelength and was maximal around the absorption peak, mainly in the blue/green and green part of the spectrum (Figure 6d). 12,[17][18][19] This was explained by anomalous dispersion of the refractive index, which meant that the absorbing axis had its minimum and maximum refractive index around the peak, on the shortwave side and longwave side, respectively, while the non-absorbing axis had an almost constant refractive index, intermediate between the minimum and maximum (Figure 3). The difference between the indices of the axes was the birefringence, which had its largest absolute values around the peak.…”

Section: Discussionmentioning

confidence: 99%

Physical basis of colors seen in Congo red-stained amyloid in polarized light

Howie

Brewer

Howell

et al. 2008

Laboratory Investigation

153

136

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Amyloid stained by Congo red is traditionally said to show apple-green birefringence in polarized light, although in practice various colors may be seen between accurately crossed polarizing filters, called polarizer and analyzer. Other colors are seen as the polarizer and analyzer are uncrossed and sometimes when the slide is rotated. Previously, there has been no satisfactory explanation of these properties. Birefringence means that a material has two refractive indices, depending on its orientation in polarized light. Birefringence can change linearly polarized light to elliptically polarized, which allows light to pass a crossed analyzer. The birefringence of orientated Congo red varied with wavelength and was maximal near its absorption peak, changing from negative (slow axis of transmission perpendicular to smears or amyloid fibrils) on the shortwave side of the peak to positive (slow axis parallel) on the longwave side. This was explained by a property of any lightabsorbing substance called anomalous dispersion of the refractive index around an absorption peak. Negative birefringence gave transmission of blue, positive gave yellow, and the mixture was perceived as green. This explains how green occurs in ideal conditions. Additional or strain birefringence in the optical system, such as in glass slides, partly or completely eliminated blue or yellow, giving yellow/green or yellow, and blue/green or blue, which are commonly seen in practice and in illustrations. With uncrossing of polarizer or analyzer, birefringent effects declined and dichroic effects appeared, giving progressive changes from green to red as the plane of polarization approached the absorbing axis and from green to colorless in the opposite way. This asymmetry of effects is useful to pathologists as a confirmation of amyloid. Rather than showing 'apple-green birefringence in polarized light' as often reported, Congo red-stained amyloid, when examined between crossed polarizer and analyzer, should more accurately be said to show anomalous colors.

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Section: Discussionmentioning

confidence: 99%

Physical basis of colors seen in Congo red-stained amyloid in polarized light

Howie

Brewer

Howell

et al. 2008

Laboratory Investigation

153

136

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“…Claims have repeatedly been made that Divry or Divry and Florkin reported a green or apple‐green colour under these conditions . This is an example of how mistaken attributions can be passed from paper to paper.…”

Section: Early Polarization Microscopic Observationsmentioning

confidence: 99%

“…Although Missmahl included a graph to show the positive birefringence of Congo red in a few of his later publications, it seems to have been based on a figure in a paper in 1959 by the German pathologists Paul Bernd Diezel and Albrecht Pfleiderer, because if it were Missmahl's own work, he gave no reference, nor did he give any details of his method or findings . Diezel and Pfleiderer measured the retardance of Congo red‐stained amyloid at several wavelengths and reported only positive birefringence, maximal around the absorption peak, although they gave no explanation of this.…”

Section: Pure Green Makes Its Appearancementioning

confidence: 99%

Origins of a pervasive, erroneous idea: The “green birefringence” of Congo red‐stained amyloid

Howie

2019

Int J Experimental Path

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Summary Congo red was discovered to stain amyloid by accident in 1922, and Congo red‐stained amyloid was shown to be birefringent on polarization microscopy in 1927. Colours, namely green and yellow, were reported under these conditions in 1945, although these are only two of various anomalous colours that may be seen, depending on the optical set‐up. In 1953 there began a dogmatic insistence that in Congo red‐stained amyloid between crossed polarizer and analyser green alone should be seen, and the finding of any other colour was a mistake. The idea that green, and only green, is essential for the diagnosis of amyloid has persisted almost universally, and virtually all mentions of Congo red‐stained amyloid say that it just shows “green birefringence” or “apple‐green birefringence.” This idea is wrong and is contrary to everyday experience, because green is seldom seen on its own under these conditions of microscopy, and often, there is no green at all. How observers maintain this unscientific position is explained by a study of its historical origins. Most of the early literature was in German or French and was usually quoted in English at second hand, which meant that misquotations, misattributions and misunderstandings were common. Few workers reported their findings accurately, hardly any attempted to explain them, and until 2008, none gave a completely satisfactory account of the physical optics. The history of Congo red‐stained amyloid is an instructive example of how an erroneous belief can become widely established even when it is contradicted by simple experience.

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“…The "green polarization color" represents a restricted view considering the fact that amyloid displays various polarization colors dependent on the thickness of the sections based on results by different groups (Diezel and Pfl eiderer, 1959;Wolman and Bubis, 1965;Cooper, 1974). Thus, the more precise view would be that amyloid is characterized by the "colored birefringence" (Cooper, 1981).…”

Section: Concerning the Value Of The Green Polarization Colormentioning

confidence: 99%

“…Because the conventional thiofl avine T staining was found to be inconsistent, it can be replaced by the optical brightener for cellulose, Phorwhite BBU, by Waldrop et al (1973). Diezel and Pfl eiderer (1959) applied a host of different dyes and other compounds to amyloids and showed that many dyes can be aligned along the amyloid fi bril axis, and some of them display colored anisotropy showing the respective complementary color under crossed Nicols. So, yellow-green anisotropy is seen with such red colors as CR, Congo corinth, Sirius red, Thiazin red, and Eosine, while binding to amyloid of such blue or violet colors as Evans Blue and Toluidine blue induce orange-red anisotropy in polarized light (Dietzel and Pfl eiderer, 1959;Wolman, 1971).…”

Section: Thiofl Avinmentioning

confidence: 99%

Congo Red Staining of Amyloid: Improvements and Practical Guide for a More Precise Diagnosis of Amyloid and the Different Amyloidoses

Linke

Protein Reviews

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Congo red (CR) is the most popular dye used as a probe for diagnosing amyloidosis, a very heterogeneous group of diseases with more than 23 chemically different amyloid syndromes of men and animals, leading to more than 400 different individual diseases. Congo red binding increases the natural anisotropy of amyloid, indicating that the elongated and planar CR molecules are aligned parallel to the axis of the amyloid α fi brila and to each other, thereby revealing a structure of amyloid. This structure was established to represent fi brils of similar dimensions, although the amyloid fi brils can be composed of many unrelated proteins. This CR-induced (positive) anisotropy displaying a green color is the hallmark of all amyloids, and is therefore used in the diagnosis of amyloidosis. The specifi city of this criterion, however, is based on very stringent conditions of staining and evaluation. This review will focus on the understanding of the CR staining procedure, its mechanism and, in particular, on its recent practical improvements by increasing the sensitivity of the CR procedure, so that minute and the earliest amyloid deposits in the course of amyloidosis can now be reliably detected in patients. This enables a very early diagnosis in the course of the disease before irreversible organ damage might have occurred, and widens the options for a successful therapy. In addition, the central role of the CR diagnostic procedure and evasion of common pitfalls in arriving at a pathogenetically exact classifi cation must only be based on the chemical nature of the amyloid deposits and not on the soluble precursors of the many different amyloidoses will be highlighted. The proposed bench-tobedside algorithm will enable the physician to arrive at the exact diagnosis for therapeutic considerations. Finally, some possible future applications of CR and analogues will be presented.

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Histochemische und polarisationsoptische Untersuchungen am Amyloid

Cited by 35 publications

References 17 publications

Physical basis of colors seen in Congo red-stained amyloid in polarized light

Physical basis of colors seen in Congo red-stained amyloid in polarized light

Origins of a pervasive, erroneous idea: The “green birefringence” of Congo red‐stained amyloid

Congo Red Staining of Amyloid: Improvements and Practical Guide for a More Precise Diagnosis of Amyloid and the Different Amyloidoses

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