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PubMed1988

Identification of regions on a 230-kilobase plasmid from enteroinvasive Escherichia coli that are required for entry into HEp-2 cells.

Certain strains of Escherichia coli can cause an invasive diarrheal disease in humans which clinically resembles shigellosis. These strains share with Shigella species the ability to enter and replicate within colonic epithelial cells and the ability to bind Congo red dye in vitro when grown at 37 degrees C. Like shigellae, they contain a large plasmid essential for virulence. A 230-kilobase (kb) plasmid from enteroinvasive E. coli was genetically marked with a transposon and mobilized into an E. coli K-12 background. This plasmid conferred upon E. coli K-12 the ability to enter and multiply within cultured epithelial cells, as well as the ability to bind Congo red. Expression of these phenotypes required growth at 37 degrees C. Transposon mutagenesis was used to identify regions on the 230-kb plasmid required for virulence. All transposon insertions which resulted in loss of the ability to enter epithelial cells, as well as the ability to bind Congo red dye, were mapped to a single 25-kb BamHI fragment. Subclones from this 25-kb region were tested for the ability to complement invasion in noninvasive derivatives. A subclone containing about 8 kb of the left end of the 25-kb BamHI fragment was capable of complementing noninvasive mutants with Tn5 insertions in this region and restored to these noninvasive mutants the ability to enter epithelial cells.

Carcinoma, Hepatocellular↗

PubMed1999

The presence, origin, and significance of A beta peptide in the cell bodies of neurons.

Interest in the A beta amyloid in Alzheimer disease (AD) has largely focused on the A beta in the neuropil, an extracellular site. Here much attention has been given to the possibility that A beta acts as a neurotoxin. However, increasing emphasis is now being given to the relationship between neurofibrillary tangles (NFT) and the degree of cognitive decline, as opposed to the relationship between decline and senile plaques, the sites of extracellular A beta deposition. This review focuses attention on the existence and significance of A beta in the cell body of the neuron. The review brings together diverse strands of literature indicating: (1) the tau-positive, paired helical filaments that are the main component of NFT are not themselves the source of the amyloid-like staining (Congo red birefringence) of PHF, and are not, in fact, an "amyloid"; (2) there is A beta within the cytoplasm of neurons affected by AD and in other conditions characterized by tau-positive neurofibrillary tangles; (3) peptides derived from portions of the A beta precursor can bind to PHF; (4) the affected neurons are the source of extracellular A beta in their vicinity and are also unable to maintain the synaptic structures that depend upon the integrity of the neuronal cell body; and (5) debates about whether the intracellular A beta is an amyloid depend upon beliefs about its tertiary structure and assumptions concerning the relationship between the size of self-aggregating A beta molecules, their tertiary structure, and their ability to generate Congo red birefringence without necessarily being detected as ultrastructural filaments 5-10 nm wide. Based upon this literature, it is suggested that the Congo red birefringence generated by NFT is caused by A beta, intimately bound to the NFT. Moreover, whether defined as an amyloid or not, the A beta in the neuronal cell body indicates an abnormal processing of the precursor molecule on the way to its ultimate transmembrane domain. Deranged neuronal functioning, which leads to this abnormal processing and/or the intracellular A beta itself, may be the cause of subsequent functional and morphologic abnormalities in the brain.

Alzheimer Disease↗

PubMed2001

Phenotypic consequences of red-white colony type variation in Mycobacterium avium.

Mycobacterium avium undergoes reversible morphotypic switching between the virulent transparent colony type and the less virulent opaque colony type. A new morphotypic switch in M. avium, termed red-white, that becomes visible when opaque colonies of clinical isolates are grown on agar media containing Congo red, was recently described. White opaque (WO) variants were found to be more resistant to multiple antibiotics than were red opaque (RO) variants. The present paper reports that transparent derivatives of RO and WO clones retain the differential Congo red binding properties of their opaque parents, indicating that the opaque-transparent switch operates independently of the red-white switch. White transparent variants were more resistant to clarithromycin and rifampin in vitro, and better able to survive within human macrophages, than their red transparent counterparts. Neither red nor white variants were markedly favoured during growth in vitro; however, red variants were better able to spread on soft agar (sliding motility), a potential selective advantage under some environmental circumstances. White-to-red switching was frequently observed in vitro and was accompanied by decreased antibiotic resistance and increased motility. Red-to-white switching has yet to be observed in vitro, indicating that the red morphotype is very stable. Significantly, some widely studied laboratory reference strains of M. avium, including strain 2151 and the genome sequence strain 104, are stable red clones. These strains are intrinsically antibiotic resistant and virulent in animal models, but they may not express genes encoding the elevated levels of antibiotic resistance and intracellular survival observed in white variants.

Anti-Bacterial Agents↗

PubMed1987

Clinical significance of virulence-related assay of Yersinia species.

During the 42-month period from June 1982 through December 1985, 215 fecal specimens from 171 patients were found to be positive for yersiniae by using a combination of CIN agar and cold enrichment. Isolates were tested for markers of virulence including carriage of a plasmid 42 megadaltons in size, calcium dependence, autoagglutination, Congo red uptake, pyrazinamidase activity, fermentation of salicin, and hydrolysis of esculin. The results were correlated to symptoms in patients. A total of 80 Yersinia enterocolitica and 52 Y. enterocolitica-like strains (42 Y. frederiksenii, 8 Y. intermedia, and 2 Y. kristensenii) were examined. Positive virulence-related tests were as follows (for Y. enterocolitica, Y. frederiksenii, Y. intermedia, and Y. kristensenii, respectively): pyrazinamidase negativity, 12.5, 0, 0, and 50%; Congo red positivity, 5, 7.1, 87.5 and 0%; calcium dependence, 3.8, 0, 0, and 0%; autoagglutination positivity, 8.8, 0, 0, and 0%; carriage of the 42-megadalton plasmid, 28.6, 73.2, 5.7, and 0; salicin and esculin negativity, 12.5, 0, 0, and 50%. The isolates recovered from symptomatic patients were characterized in relation to the presenting symptoms. Isolates from 12 of 32 (37.5%) patients with acute-onset diarrhea and 9 of 30 (30.0%) patients with chronic symptoms expressed at least one virulence feature. No individual test or group of tests was consistently associated with onset or either type of symptoms. Routine testing of plasmid carriage, uptake of Congo red, calcium dependence, autoagglutination, and pyrazinamidase activity did not appear to provide information that would link the presence of symptoms with the virulence potential of fecal isolates of yersiniae.

Acute Disease↗

PubMed2000

Biodegradation of azo dyes in a sequential anaerobic-aerobic system.

A sequential anaerobic aerobic treatment process based on mixed culture of bacteria isolated from textile dye effluent-contaminated soil was used to degrade sulfonated azo dyes Orange G (OG), Amido black 10B (AB), Direct red 4BS (DR) and Congo red (CR). Under anaerobic conditions in a fixed-bed column using glucose as co-substrate, the azo dyes were reduced and amines were released by the bacterial biomass. The amines were completely mineralized in a subsequent aerobic treatment using the same isolates. The maximum degradation rate observed in the treatment system for OG was 60.9 mg/l per day (16.99 mg/g glucose utilized), for AB 571.3 mg/l per day (14.46 mg/g glucose utilized), for DR 112.5 mg/l per day (32.02 mg/g glucose utilized) and for CR 134.9 mg/l per day (38.9 mg/g glucose utilized).

Aerobiosis↗

PubMed1998

[Clinicopathological and diagnostic study of amyloidosis of oral maxillofacial area].

OBJECTIVE: To study the clinicopathological features of amyloidosis studied in oral maxillofacial area and the diagnostic methods. METHODS: HE staining and staining of alkaline Congo red, Immunohistochemical staining, Sections examined by transmitted and polarized light microscopy, Transmitted electron microscopy. RESULTS: 14 cases of the disease were reported. Clinically, the patients usually had progressive enlargement and solidness of the tongue (macroglossia, 12 cases), hard nodules or cords of the cheek and lip mucosa (8 cases), single or multiple hard masses of submandibular and submental areas (6 cases), and ecchymosis or petechiae of the face, neck, chest or oral mucosa. Microscopically, the disease is characterized by the even pink amyloid protein deposit in the soft tissues and the wall of blood vessles, which shows positive staining of alkaline Congo red, Immunohistochemical staining can differentiate the primary amyloidosis from secondary one. Ultrastructurally, Amyloid protein appeares as felt-like finely filament. CONCLUSION: Amyloidosis involving in oral maxillofacial area mainly arise in tongue, less frequently, in buccal and lip mucosa, salivary glands. It is not difficulty to dignosis the disease by HE staining combining with staining of alkaline Congo red and other specific staining methods. Ultrastructural and immunohistochemical study is helpful to make show the dignosis.

Adult↗

PubMed1996

Generalised AA-amyloidosis in a bat (Pipistrellus pipistrellus).

Generalized amyloidosis was found to be the cause of death in a female adult insectivorous pipistrelle bat (Pipistrellus pipistrellus) after chronic wound inflammation. Large amounts of amyloid were detected in liver, spleen, kidneys, stomach, intestine, lymphatic tissues, and endocrine and salivary glands. Congo red staining and green birefringence identified amyloid; the Congo red staining was sensitive to potassium permanganate oxidation. The amyloid was further classified immunohistochemically. The deposits reacted with two anti-human-AA-amyloid monoclonal antibodies in a peroxidase-antiperoxidase reaction, whereas no reaction was found with antibodies specific for other types of amyloid. Thus, the bat amyloid deposits were identified as generalized reactive AA-amyloidosis.

Amyloidosis↗

PubMed2003

Amyloid-enhancing factor mediates amyloid formation on fibroblasts via a nidus/template mechanism.

OBJECTIVE: To determine the mechanism by which amyloid-enhancing factor (AEF) promotes amyloid deposition, and to test whether AEF seeds deposition of serum amyloid A (SAA) and facilitates conversion to beta-sheet structure. METHODS: Fibroblasts were cultured with mouse recombinant SAA1.1 and AEF, SAA1.1, or AEF. AEF was prepared as a glycerol extract of spleen from amyloidotic mice. Amyloid was identified by staining with Congo red and examining for green birefringence under polarized light. SAA was localized immunohistochemically. Texas Red-labeled SAA was visualized in living cultures by fluorescence confocal microscopy. AEF was characterized by Western blot analysis using anti-SAA antiserum and N-terminal sequence analysis. Subunits comprising amyloid in fibroblast cultures were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. RESULTS: Amyloid was produced in fibroblast cultures by an AEF-dependent mechanism. AEF, added to culture medium as insoluble protein precipitates, adhered to fibroblast monolayers. SAA bound preferentially to the adherent precipitates. Coincident with SAA binding, precipitates developed an affinity for Congo red. Over time, as more SAA was added, networks of Congo red-positive material producing bright green birefringence also developed outward from AEF precipitates. Amyloid built upon AEF in this manner was composed of full-length SAA. No amyloid was produced in cultures treated with either SAA or AEF alone. SAA and SAA peptides processed in the C-terminal region were the most prominent proteins in the glycerol-extracted AEF preparation. CONCLUSION: AEF binds to fibroblast monolayers and acts as a sink for SAA. SAA that collects on AEF assembles into an amyloid structure. Thus, it is concluded that AEF serves as both a nidus and a template for amyloid formation.

Animals↗

PubMed2003

The structure and protein binding of amyloid-specific dye reagents.

The self-assembling tendency and protein complexation capability of dyes related to Congo red and also some dyes of different structure were compared to explain the mechanism of Congo red binding and the reason for its specific affinity for beta-structure. Complexation with proteins was measured directly and expressed as the number of dye molecules bound to heat-aggregated IgG and to two light chains with different structural stability. Binding of dyes to rabbit antibodies was measured indirectly as the enhancement effect of the dye on immune complex formation. Self-assembling was tested using dynamic light scattering to measure the size of the supramolecular assemblies. In general the results show that the supramolecular form of a dye is the main factor determining its complexation capability. Dyes that in their compact supramolecular organization are ribbon-shaped may adhere to polypeptides of beta-conformation due to the architectural compatibility in this unique structural form. The optimal fit in complexation seems to depend on two contradictory factors involving, on the one hand, the compactness of the non-covalently stabilized supramolecular ligand, and the dynamic character producing its plasticity on the other. As a result, the highest protein binding capability is shown by dyes with a moderate self-assembling tendency, while those arranging into either very rigid or very unstable supramolecular entities are less able to bind.

Amyloid↗

PubMed2005

Mechanism of A beta(1-40) fibril-induced fluorescence of (trans,trans)-1-bromo-2,5-bis(4-hydroxystyryl)benzene (K114).

K114, (trans,trans)-1-bromo-2,5-bis(4-hydroxystyryl)benzene, is a fluorescent Congo Red analogue that binds tightly to amyloid fibrils, but not the monomeric proteins, with a concomitant enhancement in fluorescence. The mechanism for the low aqueous fluorescence and the subsequent enhancement by A beta(1-40) fibrils was investigated by fluorescence spectroscopy and binding analysis. K114's unusually low buffer fluorescence is due to self-quenching in sedimentable aggregates or micelles which upon interacting with amyloid fibrils undergo an enhancement in fluorescence intensity and shifts in the excitation and emission spectra. These spectral changes are suggestive of a stabilization of the phenolate anion, perhaps by hydrogen bonding, rather than an increase in the microenvironment dielectric constant or dye immobilization. 1,4-Bis(4-aminophenylethenyl)-2-methoxybenzene, which lacks the phenol moiety, and X-34, which contains a stabilized phenol (pK approximately 13.4), do not display the phenolate anion fluorescence in the presence of fibrils. The apparent affinity of K114 for fibril binding is 20-30 nM with a stoichiometry of 2.2 mol of K114/mol of A beta(1-40) monomer. Competition studies indicate that K114 and Congo Red share a site, but K114 does not bind to sites on A beta(1-40) fibrils for neutral benzothiazole (BTA-1), cationic thioflavin T, or the hydrophobic (S)-naproxen and (R)-ibuprofen molecules. Comparison of benzothiazole binding stoichiometry which has been suggested to reflect disease-relevant amyloid structures to that of Congo Red analogues which reflect total fibril content may be useful in defining biologically pertinent conformational forms of amyloid.

Amyloid↗

PubMed1998

Pathologic amyloid beta-protein cell surface fibril assembly on cultured human cerebrovascular smooth muscle cells.

Cerebrovascular amyloid beta-protein (A beta) deposition is a key pathological feature of Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D). A beta(1-40) containing the E22Q HCHWA-D mutation, but not wild-type A beta(1-40), potently induces several pathologic responses in cultured human cerebrovascular smooth muscle cells, including cellular degeneration and a robust increase in the levels of cellular A beta precursor. In the present study, we show by several quantitative criteria, including thioflavin T fluorescence binding, circular dichroism spectroscopy, and transmission electron microscopic analysis, that at a concentration of 25 microM neither HCHWA-D A beta(1-40) nor wild-type A beta(1-40) appreciably assembles into beta-pleated sheet-containing fibrils in solution over a 6-day incubation period. In contrast, at the same concentrations, HCHWA-D A beta(1-40), but not wild-type A beta(1-40), selectively binds and assembles into abundant fibrils on the surfaces of cultured human cerebrovascular smooth muscle cells. The simultaneous addition of an equimolar concentration of the dye Congo red prevents the cell surface fibril assembly of HCHWA-D A beta(1-40). Moreover, Congo red effectively blocks the key pathologic responses induced by HCHWA-D A beta(1-40) in these cells. The present findings suggest that the surface of human cerebrovascular smooth muscle cells may selectively orchestrate the assembly of pathogenic A beta fibrils and that cell surface A beta fibril formation plays an important role in causing the pathologic responses in these cells.

Amyloid beta-Peptides↗

PubMed1979

Improved methodology for the Grassi test for intraoperative determination of completeness of vagotomy.

The Grassi test for completeness of vagotomy is a useful adjunct to vagotomy that aids the surgeon in severing all the vagal innervation of the acid-producing portion of the stomach. The Congo Red stick allows the surgeon to perform the Grassi test with a significant reduction in the amount of equipment and personnel required by either pH electrode or liquid Congo Red methods.

Congo Red↗

PubMed2006

The two-component regulatory system mtrAB is required for morphotypic multidrug resistance in Mycobacterium avium.

Clinical isolates of the opportunistic pathogen Mycobacterium avium complex (MAC) undergo a reversible switch between red and white colony morphotypes on agar plates containing the lipoprotein stain Congo red. Compared to their isogenic red counterparts, white morphotypic variants are more virulent and more resistant to multiple antibiotics. This report shows that the two-component regulatory system mtrAB is required for the red-to-white switch as well as for other morphotypic switches of MAC. A mutant with a transposon insertion in the histidine protein kinase gene mtrB was isolated from a morphotypically white parent clone. The mutant resembled a naturally occurring red morphotypic variant in that it stained with Congo red, was sensitive to multiple antibiotics, and was permeable by a fluorescent DNA stain. However, it differed from a red variant in that it could not switch to the white or transparent morphotype, and it could not survive intracellularly within macrophage-like cells. Transcomplementation with a cloned wild-type mtrB gene restored to the mutant the ability to form impermeable, drug-resistant white and transparent variants. Quantitative reverse transcriptase PCR showed that mtrB was required for the normal expression of cell surface Mce proteins, some of which are up-regulated in the red-to-white switch. The results indicate that mtrAB functions in regulating the composition and permeability of mycobacterial cell walls and plays a role in the reversible colony type switches of MAC.

ATP-Binding Cassette Transporters↗

PubMed1982

Renal amyloidosis in related Abyssinian cats.

Renal amyloidosis was diagnosed in 8 related Abyssinian cats. The kidneys were characterized pathologically by medullary interstitial and glomerular amyloid deposition, interstitial fibrosis, and papillary necrosis. Amyloid deposits were birefringent under polarized light after Congo red staining, were thioflavine-T positive, and lost Congo red staining after permanganate oxidation. Four of the cats were evaluated clinically. Two of these cats were terminally uremic, with nonregenerative anemia, azotemia, hyperphosphatemia, metabolic acidosis, mild hyperglycemia, isosthenuria, proteinuria, cylindruria, and mild hematuria. The remaining 2 cats were only moderately azotemic. Three of the cats had severe gingivitis and all 4 cats had hyperproteinemia due to hyperglobulinemia.

Amyloidosis↗

PubMed1993

Amyloid-like properties of peptides flanking the epitope of amyloid precursor protein-specific monoclonal antibody 22C11.

Alzheimer's disease is one of the prevalent forms of human dementia. Its pathology is distinguished by proteinaceous deposits ("amyloid") in the brain. They contain a peptide (beta A4) that is proteolytically derived from a larger transmembrane protein. To follow the different metabolic pathways of this Amyloid Precursor Protein (APP) may thus lead to the elucidation of the molecular basis of Alzheimer's disease. Specific antibodies are necessary tools for this task. Using synthetic peptides, we have characterized the epitope of the APP-specific monoclonal antibody 22C11; it is localized between residues 66 and 81 of APP. Some of the peptides flanking this site exhibited properties generally associated with amyloid, i.e. low solubility, filament formation, and birefringence after Congo Red staining. Exploiting differences in the peptides' aggregational properties, we present evidence that the two dyes Eosin and Direct Red 254, in conjunction with classical amyloid staining by Congo Red, can be used to characterize aggregating, amyloid-like peptides in vitro.

Amino Acid Sequence↗

PubMed2001

Enhanced anti-Shigella activity of erythromycin supplemented with sulfadiazine.

Sulfadiazine enhanced the anti-Shigella activity of erythromycin. Erythromycin passes through the type III secretion apparatus and suppresses the growth of invasive Shigella organisms. Sulfadiazine enhanced this effect at the concentration under minimum inhibitory concentration and it came from not only the folate-inhibiting activity but also from a new function. It has proved that sulfadiazine stimulated type III secretion in Shigella as determined from the secretion of the pathogenic protein IpaB. As Congo red induced secretion of Ipa proteins and uptake of erythromycin through the type III secretion gate, sulfadiazine which is similar to Congo red in chemical structure may induce the uptake in the same way.

Animals↗

PubMed2005

An Abeta sequestration approach using non-antibody Abeta binding agents.

Amyloid beta (Abeta) has been considered as a primary cause of Alzheimer's disease (AD), and Abeta lowering approaches have been tested. Active immunization against Abeta is one of several promising Abeta-lowering approaches. Two mechanisms have been proposed: enhancement of microglial phagocytosis and Abeta sequestration (also called "peripheral sink"). We hypothesized that Abeta sequestration without immune modulation is sufficient to reduce the brain Abeta load and have demonstrated effective sequestration with Abeta binding agents that do not stimulate an immune reaction. Recent reports from other groups showed two other non-immune related Abeta binding agents, which have no structural relation to compounds we previously tested, reduced brain Abeta after peripheral administration. Congo red is a chemically synthesized small molecule that has binding affinity to Abeta. In the present study, we tested three Congo red derivatives in Abeta plaque-forming mice at an early pathological stage. Unfortunately, peripheral administration for three weeks did not substantially alter brain Abeta load. Optimized Abeta binding agents with high affinity to soluble Abeta are necessary for the sequestration approach.

Amyloid beta-Peptides↗

PubMed2004

Primary diffuse tracheobronchial amyloidosis in a dog.

Primary diffuse tracheobronchial amyloidosis was diagnosed at necropsy in an intact male Akita dog aged 11 years, a non-productive chronic cough having been the only related clinical sign. Histologically, eosinophilic hyalinized deposits were found as a band in the lamina propria underneath the epithelium of the trachea and bronchi. When stained with Congo red, apple-green birefringence was observed in the deposits viewed with polarized light. The amyloid did not lose sensitivity to Congo red staining after incubation with potassium permanganate, indicating that it was of the AL (amyloid light chain) type. Ultrastructural features of the amyloid included a typical fibrillar meshwork with individual fibrils measuring 9.5 to 10.5 nm in diameter. This is the first report of primary diffuse tracheobronchial amyloidosis in the dog.

Amyloid↗