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PubMed1983

The characteristic three-banded birefringence of ligamentum nuchae elastic fibres indicates ordered micellar texture.

The ultrastructural organization of the elastic fibres of bovine ligamentum nuchae is still controversial (Kádár 1979; Sandberg 1976; Sandberg et al. 1981; Quintarelli et al. 1973; Gosline 1976). Polarization microscopy demonstrated convincingly, contrary to a recent negative report (Aaron and Gosline 1980), an ordered birefringent micellar texture (Schmidt 1939; Romhányi 1965; Fischer 1979). The three-banded anisotropic pattern of the fibres can be explained by the optical interference of two micellar textures of opposite orientation, one arranged circularly in the surface layer and the other oriented longitudinally in the axial core of the fibres (Romhányi 1965). Analysis of the underlying molecular mechanism for the anisotropic staining reaction of these fibres with Congo red led to the conclusion that this is due to a definite structural order of specific cross-linking segments within the random network of elastin. The anisotropic staining reaction of the elastic fibres with Congo red is described as the most simple method to demonstrate the three-banded birefringent pattern of ligamentum nuchae elastic fibres even in histologic sections.

Animals↗

PubMed1997

Amyloid beta-protein (Abeta) 1-40 but not Abeta1-42 contributes to the experimental formation of Alzheimer disease amyloid fibrils in rat brain.

Two major C-terminal variants ending at Val40 and Ala42 constitute the majority of amyloid beta-protein (Abeta), which undergoes postsecretory aggregation and deposition in the Alzheimer disease (AD) brain. To probe the differential pathobiology of the two Abeta variants, we used an in vivo paradigm in which freshly solubilized Abeta1-40 or Abeta1-42 was injected into rat brains, followed by examination using Congo red birefringence, Abeta immunohistochemistry, and electron microscopy. In the rat brain, soluble Abeta 1-40 and Abeta1-42 formed aggregates, and the Abeta1-40 but not the Abeta1-42 aggregates showed Congo red birefringence. Electron microscopy revealed that the Abeta1-40 aggregates contained fibrillar structures similar to the amyloid fibrils of AD, whereas the Abeta1-42 aggregates contained nonfibrillar amorphous material. Preincubation of Abeta1-42 solution in vitro led to the formation of birefringent aggregates, and after injection of the preincubated Abeta1-42, the aggregates remained birefringent in the rat brain. Thus, a factor or factors might exist in the rat brain that inhibit the fibrillar assembly of soluble Abeta1-42. To analyze the postsecretory processing of Abeta, we used the same in vivo paradigm and showed that Abeta1-40 and Abeta1-42 were processed at their N termini to yield variants starting at pyroglutamate, and at their C termini to yield variants ending at Val40 and at Val39. Thus the normal rat brain could produce enzymes that mediate the conversion of Abeta 1-40/1-42 into processed variants similar to those in AD. This experimental paradigm may facilitate efforts to elucidate mechanisms of Abeta deposition evolving into amyloid plaques in AD.

Alzheimer Disease↗

PubMed1983

Impact of choice of anesthetic with vagotomy testing.

Incomplete vagotomy is the most important cause of recurrent ulcer disease. Despite this, intraoperative vagotomy testing has not gained widespread acceptance. We used a technique with Congo red, a nontoxic azine dye that turns black (pH, 3.0) intraoperatively. The vagolytic effects of various general anesthetics has been shown. We found that halothane, used as a general anesthetic, combined with pentagastrin administration as a vagally synergistic stimulant, produced the most reliable, safe, and reproducible result when using Congo red intraoperatively.

Anesthesia, General↗

PubMedDate not supplied

[The choice of the method for determining the potential pathogenicity of shigellae].

The biological characteristics of 196 Shigella strains, isolated in regions with different levels of the geomagnetic field tension, were under study. Strains able to adsorb Congo red, characterized by antilysozyme activity, hydrophobic, resistant to gentamycin, monomycin, kanamycin, rifampicin were more frequently isolated in the regions with a higher tension of the field, this being confirmed by a stable correlation. The ability of Shigellae to fix Congo red correlated with the before signs and with colicinogenicity, therefore this test may be recommended for the assessment of Shigella virulence.

Anti-Bacterial Agents↗

PubMed1999

Effects of sequential proline substitutions on amyloid formation by human amylin20-29.

Amylin, also known as islet amyloid polypeptide (IAPP), is the major protein component of the fibril deposits found in the pancreas of individuals with type II diabetes. The central region of amylin, residues 20-29, has been implicated as a key determinate of amyloid formation. To establish which positions are most important for amyloid formation, the wild-type sequence of the 20-29 fragment and a set of 10 variants have been synthesized in which a proline was placed at each position. Proline is energetically unfavorable in the extended cross-beta structure found in amyloid. If a particular position is critical for amyloid formation, then substitution with a proline should inhibit amyloid formation. A proline substitution at any position inhibited aggregation and amyloid formation. Substitution of Asn22, Gly24, and residues 26-28 had the largest effect. Fourier transform infrared (FTIR) spectroscopy showed little secondary structure in these peptides, and transmission electron microscopy (TEM) showed mostly amorphous material. The peptides were much more soluble than the wild-type sequence, and no birefringence was observed with Congo Red staining. Proline substitutions at the N (residues 20 and 21) and C termini showed the least effect. These peptides showed the classic fibril morphology, a significant amount of beta-sheet structure, and exhibited green birefringence when stained with Congo Red. The results indicate that residues 22, 24, and 26-28 play a key role in formation of amyloid by amylin. Positions 23 and 25 also appear to be important, but may be less critical than positions 22, 24, and 26-28.

Amino Acid Sequence↗

PubMed1985

Pars plana vitrectomy in a case of amyloidosis of the vitreous.

A pars plana vitrectomy was performed in a case of vitreous opacities caused by generalized amyloidosis. Vision improved from 2/300 to 5/5 after surgery. The vitreous specimen stained orange-red with congo-red staining and showed the typical yellow-green birefringence with polarized light. The literature on the surgical treatment of amyloidosis of the vitreous is reviewed.

Aged↗

PubMed2004

Amyloid tumor in the anterior mediastinum: report of a case.

A 33-year-old woman being treated for rheumatoid arthritis was referred to our hospital for investigation of a mediastinal mass. A chest computed tomography scan showed an anterior mediastinal mass, 8.5 x 7.0 cm in size, with a cystic lesion and calcification. These findings were suggestive of either a noninvasive thymoma or a mature teratoma. Therefore, we performed tumor resection and thymectomy. Histologically, the tumor consisted of diffuse deposits of massive eosinophilic amorphous material. The tumor was stained red-orange by Congo red, and the staining disappeared following potassium permanganate digestion. Based on these findings, a diagnosis of reactive amyloidosis of the amyloid A-protein-derived type was made. Amyloidosis in the mediastinum has rarely been described.

Adult↗

PubMed2002

Biodecolourization of azo and triphenylmethane dyes by Dichomitus squalens and Phlebia spp.

Nine white-rot fungal strains were screened for biodecolourization of brilliant green, cresol red, crystal violet, congo red and orange II. Dichomitus squalens, Phlebia fascicularia and P. floridensis decolourized all of the dyes on solid agar medium and possessed better decolourization ability than Phanerochaete chrysosporium when tested in nitrogen-limited broth medium.

Azo Compounds↗

PubMed2006

Acute renal failure and nephrotic range proteinuria due to amyloidosis in an HIV-infected patient.

Amyloidosis is an uncommon cause of renal disease in HIV-positive patients. Diagnosis is challenging, treatment options are limited, and prognosis remains poor. We discuss an HIV-positive patient with acute renal failure and nephrotic range proteinuria. The differential diagnosis included nephropathy due to trimethoprim/sulfamethoxazole, tenofovir, HIV, hepatitis C, heroin, or multifactorial causes. Serum and urine study findings were inconclusive. Rapid clinical deterioration ensued and a renal biopsy was performed. Pathologic examination revealed eosinophilic, amorphous material in the glomerular tufts that stained red-orange with Congo red stain. Immunohistochemical analysis confirmed amyloid A (AA) amyloidosis. AA amyloidosis occurs as a complication of chronic infection or chronic inflammatory disease. It has been reported in intravenous or subcutaneous drug abusers, some of whom were HIV-positive. This case underscores the importance of tissue diagnosis to determine the cause of renal disease in HIV-positive patients. Clinical diagnosis, based on CD4 count, viral load, and degree of proteinuria, may not predict the pathological diagnosis in HIV-positive patients.

Acute Kidney Injury↗

PubMed1987

Amyloid deposits in pituitary adenomas. Differentiation of two types.

Two different types of amyloid deposits in pituitary adenomas are described herein. The deposits of the first type are stellate and perivascular masses, with fibrillary inclusions occurring in the intercellular space. No immunoreactive cytokeratin can be detected in the deposits, and the masses are secreted by the adenoma cells. A second, rarer type is characterized by spheroids (40 to 1500 micron in diameter) in which immunoreactive cytokeratin fibrils are present. The fibrils originate in the adenoma cells adjacent to the deposits. The amyloid nature of both types of deposits can be proved by intense red staining with Congo red, green dichroism, and positive immunostaining with antibodies raised against serum amyloid P component. Adenomas with amyloid spheroids are very rare, and most have been proved or suspected prolactin-producing adenomas.

Adenoma↗

PubMed1982

[Culture medium for the isolation of group B Streptococcus].

Comparative studies were carried out on a new medium--a soybean agar of the Difco type with the addition of beta-staphylococcus toxin, washed sheep erythrocytes, esculin, and Congo red to isolate and differentiate the streptococci of the serologic B group. Congo red was used in dilution of 1:10000 to suppress the beta-hemolysis of the streptococci belonging to other serologic groups. The higher objectivity of the final results required the use of a blood agar and a medium with thallium sulfate and crystal violet--nutrient media for the bacteriologic diagnostics of mastitis. It was established with all three lines of research of selected cultures (control strains) through sampling milk of the four quarters of the udder and pooled milk by groups and farms that soybean agar proved superior to the remaining nutrient media, more specifically in the diagnosis of mastitis caused by streptococci of the serologic group.

Animals↗

PubMed1997

Dialysis arthropathy: identification and evaluation of a subset of patients with unexplained inflammatory effusions.

OBJECTIVE: Rheumatic disorders have been reported in patients with chronic renal failure treated with hemodialysis. We identified and evaluated 9 patients undergoing hemodialysis with inflammatory joint effusions not explained by known causes such as gout and bacterial infection. METHODS: Forty-nine consecutive synovial fluid (SF) analyses on 41 dialysis patients were reviewed. Nine with unexplained inflammatory arthritis were studied in detail. SF analysis included polarized light examination, alizarin red S stain, Congo red stain, cultures, transmission electron microscopy, and electron probe elemental analysis. RESULTS: SF leukocyte counts ranged from 4550 to 36,000/mm3 with 44-98% neutrophils. No infections were identifiable in these patients. Findings evaluated as possible factors in the joint inflammation included apatite crystals, iron, lipids, amyloid, and difficult to diagnose nonbacterial infections such as hepatitis C. CONCLUSION: Some highly inflammatory joint effusions in patients undergoing chronic hemodialysis are not due to pyogenic infections and may be attributable to other factors.

Adult↗

PubMed2001

Pseudomonas aeruginosa protease IV enzyme assays and comparison to other Pseudomonas proteases.

Pseudomonas aeruginosa secretes multiple proteases that have been implicated as virulence factors and the detection of each specific enzyme can be difficult to determine. Unlike the three Pseudomonas enzymes that have been well characterized (elastase A, elastase B, and alkaline protease), the activity of protease IV in multiple assays has yet to be described. This study defines new assays for Pseudomonas proteases and compares protease IV activity to the activities of elastase A, elastase B, and alkaline protease. Six in vitro assays were studied: zymography, elastin congo red assay, staphylolytic assay, colorimetric peptide assay, solid-phase colorimetric peptide assay, and poly-l-lysine degradation. Casein zymography distinguished protease IV from elastase B and alkaline protease, and gelatin zymography differentiated all four proteases. The elastin congo red assay detected mainly elastase B while the staphylolytic assay was specific for elastase A. Protease IV activity was assayed specifically by the colorimetric assay and two new assays, the solid-phase colorimetric assay and degradation of poly-L-lysine in the presence of EDTA. Alkaline protease could be specifically assayed by poly-L-lysine degradation in the presence of N-alpha-p-tosyl-L-lysine chloromethyl ketone. The results identified three specific assays for protease IV, a new assay specific for alkaline protease, and showed that protease IV has a distinct enzymatic specificity relative to the three other Pseudomonas proteases.

Colorimetry↗

PubMed1996

Prion protein amyloid: separation of scrapie infectivity from PrP polymers.

The prion protein (PrP) undergoes a profound conformational change when the cellular isoform (PrPc) is converted into the scrapie form (PrPSc). Limited proteolysis of PrPSc produces PrP27-30 which readily polymerizes into amyloid. To study the structure of PrP amyloid, we employed organic solvents that perturb protein conformation. 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP), which promotes alpha-helix formation, modified the ultrastructure of rod-shaped PrP amyloids, producing flattened ribbons with a more regular substructure. As the concentration of HFIP was increased, the beta-sheet content and proteinase K resistance of PrP27-30 as well as prion infectivity diminished. HFIP reversibly decreased the binding of Congo red dye to the rods, whereas inactivation of prion infectivity was irreversible. In contrast to 10% HFIP, 1,1,1-trifluoro-2-propanol (TFIP) did not inactivate prion infectivity but, similarly to HFIP, TFIP did alter the morphology of the rods and abolished Congo red binding. Our studies separate prion infectivity from the amyloid properties of PrP27-30 and underscore the dependence of prion infectivity on PrPSc conformation. Our results also demonstrate that the specific beta-sheet-rich structures required for prion infectivity are different from those needed for amyloid formation.

1-Propanol↗

PubMed1977

A simple method of determining the boundary between the antrum and corpus of the stomach. Part 2. Electric vagal stimulation in dogs.

Our previous work demonstrated that electric vagal stimulation in conjunction with Congo red as a dye-indicator is the faster and more reliable method for delineating the corpus-antral boundary in rats. Based on this finding, our study was extended to a larger animal model, the dog; this study proved the electrical vagal stimulation along with Congo red is a reliable method for adequate demonstration of this corpus-antral boundary. No untoward effect on the cardiac function was observed during stimulation of subdiaphragmatic portion of vagal trunks.

Animals↗

PubMed1990

Identification and cloning of a hemin storage locus involved in the pigmentation phenotype of Yersinia pestis.

The temperature-dependent absorption of sufficient exogenous hemin or Congo red to form pigmented colonies of Yersinia pestis has been termed the pigmentation phenotype (Pgm+). Spontaneous mutation to a Pgm- phenotype results in the loss of a number of divergent physiological characteristics, including the ability to store hemin and to bind Congo red at 26 degrees C. In this study, we generated and isolated transposon insertion mutants that are hemin storage negative (Hms-) and therefore unable to form pigmented colonies. These mutations are due to single mini-kan insertions within a 19.5-kilobase (kb) SalI fragment of chromosomal DNA. Restriction site analysis of eight mutants identified a minimum of six potentially different insertion sites spanning an approximately 10-kb hemin storage (hms) locus. The 19.5-kb SalI fragment (containing approximately 18 kb of Y. pestis DNA and the mini-kan insert) was cloned from one of these mutants, KIM6-2012. By using this cloned fragment as a DNA probe, the mechanism of spontaneous mutation to a Pgm- phenotype was identified as a massive deletion event. The deletion spans at least 18 kb of genomic DNA in spontaneous Pgm- mutants from nine separate strains of Y. pestis. DNA adjacent to the mini-kan insert was used to identify a clone containing a wild-type hms locus. A spontaneous Pgm- mutant of Y pestis KIM containing this clone exhibits an Hms+ phenotype. The hms::mini-kan mutations and cloned wild-type hms locus generated in this study will greatly aid in identifying the function of hemin storage in Y. pestis.

Biological Transport↗

PubMed2003

Spectroscopic investigation on gel-forming beta-sheet assemblage of peptide derivatives.

The conformational studies of peptide derivatives A and B in a gel state were studied by using circular dichroism (CD), Fourier transformed infrared (FTIR), and fluorescence spectroscopic techniques. Birefringence and electron microscopic studies were carried out to characterize the morphological aspects of the fibrils in the gel. The FTIR spectra of the peptides show the absence of free NH in the gel state, implying that the intermolecular hydrogen-bond formation is the driving force for the aggregation. The CD spectrum of the peptide gels shows the presence of antiparallel and parallel beta-sheet conformation for peptide derivatives A and B, respectively. Electron microscopic studies (EM) of the peptide derivatives A and B reveal that peptide A formed rigid, rod-like structures without cross-linking and peptide B formed loose fibrils organized into highly noncovalently cross-linked mesh-like structural aggregates. Peptide A was much more soluble in alcoholic solvents than peptide B, and no birefringence was observed with Congo red (CR) staining in the temperature range of 0-80 degrees C. The spectroscopic studies indicate that peptide B consists of domains having a significant amount of beta-sheet structure and exhibiting golden yellow birefringence between 53 and 56 degrees C when stained with Congo red. On the other hand, peptide A gives no evidence of birefringence under polarized light. Fluorescence probe binding studies with pyrene in gel state with peptides A and B indicates the polarity in the interior of the aggregates. The data presented in the present work indicate that peptide B forms fibrils, which is similar to amyloid aggregates that are present in biological systems.

Amino Acid Sequence↗

PubMed2006

Histochemical differential diagnosis and polarization optical analysis of amyloid and amyloidosis.

Amyloidosis is characterized by extracellular deposition of protein fibrils of chemically heterogeneous composition. Early recognition and identification of amyloid deposits allows an early start of therapy, which may entail a better prognosis. Congo red staining according to Romhányi (1971) is a highly specific and sensitive method for early microscopic recognition of amyloidosis. The main and most important types of amyloidosis may be distinguished by classic histochemical methods of performate pretreatment according to Romhányi (1979), or by KMnO4 oxidation according to Wright (1977) followed by Congo red staining and viewed under polarized light. Differences in the speed of breakdown (disintegration) of amyloid deposits according to Bély and Apáthy allow a more precise distinction of various types of amyloid.

Amyloid↗