SEARCH · Search PubMed

Results for “CONGO”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources

PubMed1999

Nikkomycin Z counteracts Rylux BSU and Congo red inhibition of Saccharomyces cerevisiae growth but does not prevent formation of aberrant cell walls.

Rylux BSU and congo red bind to chitin, interfere with proper cell-wall assembly, and stimulate chitin synthesis by increasing, most probably, chitin synthase 3 (ChS3) levels in Saccharomyces cerevisiae. On the other hand, the antibiotic nikkomycin Z inhibits chitin synthesis competitively. As ChS3 is the critical target of nikkomycin Z, its effect was tested in cells inhibited in growth by Rylux BSU or Congo red. Nikkomycin Z counteracted this inhibition but did not counteract aberrant cell-wall formation. These results indicate that chitin synthesis stimulation is the key step in Rylux BSU and congo red inhibition and support the idea that increase in chitin synthesis represents a compensatory response to damaged cell-wall structure. As Rylux BSU and congo red bind to newly synthesized chitin, further damage is caused in the wall and the response works in this case contrariwise. Nikkomycin Z breaks this vicious circle by counteracting the chitin synthesis stimulation.

Aminoglycosides↗

PubMed2004

The deforestation of rural areas in the Lower Congo Province.

The Lower Congo is one of eleven provinces in the Democratic Republic of Congo, and is located southwest of Kinshasa Town Province. It has an area of approximately 53.947 km2 with a population of 1,504,361 at an estimated 237 persons per km2. The Province comprises five districts, including Lukaya and Cataracts where rural poverty is severe and the population struggle to make a living through agriculture and woodcutting. These activities result in excessive resource exploitation. The high demand for foodstuffs and the high consumption of wood (for energy, construction and export) in Kinshasa, the capital city of the Democratic Republic of Congo and the expanding towns of Matadi and Boma in the Lower Congo Province, are speeding the deforestation rate and unbalancing forest ecosystems. In addition there is the stress resulting from reduced josher (the rest period for agriculture ground), plus climate change and erosion. The phenomena that that we need to address in these two districts include deforestation, reduced josher, excessive agriculture, erosion, burning and climate change which taken together largely explain the current soil degradation. These areas are marked by excessive post deforestation savannah formation and extended areas of sandy soil, distributed throughout grass and shrub savannahs. This desertification, which is rampant in Lukaya and Cataracts, risks imprisoning the rural population in a vicious cycle of poverty if adequate solutions are not found.

Agriculture↗

PubMed1987

Endoscopic Congo red test during proximal gastric vagotomy.

Although proximal gastric vagotomy is widely performed as an elective treatment for duodenal ulcer, the incidence of recurrent ulcer is troublesome. There are several theories to explain recurrent ulcers, and important technical steps should be considered when performing proximal gastric vagotomy. The use of an intraoperative test may allow more accurate performance of the operation and more complete vagotomy of the parietal cell mass. This report describes the use of the endoscopic Congo red test in patients during proximal gastric vagotomy. The test allows rapid and accurate mapping of areas of the stomach with intact vagus and secretory nerves after operative vagotomy, and can be repeated several times if necessary to verify completion of the vagotomy. The use of universally available equipment and the potential for intraoperative and postoperative use are other attractive features of the test. Use of the endoscopic Congo red test provides physiologic evidence that vagus secretory nerve fibers traverse the right and left gastroepiploic nerves, leading us to believe that the gastroepiploic nerves should be routinely divided during proximal gastric vagotomy. In patients with recurrent duodenal ulcer requiring reoperation, the endoscopic Congo red test allows preoperative demonstration of the site of the intact vagal nerve trunks. The endoscopic Congo red test deserves further investigation and wider application during operations for chronic duodenal ulcer.

Congo Red↗

PubMed1983

Conversion of Congo red and 2-azoxyfluorene to mutagens following in vitro reduction by whole-cell rat cecal bacteria.

Congo red, an azo dye derived from benzidine, and 2-azoxyfluorene, a derivative of 2-aminofluorene, were reduced during overnight incubation with a suspension of rat intestinal bacteria. High performance liquid chromatography and ultraviolet spectral analysis verified the presence of benzidine in extracts of the Congo red incubations and 2-aminofluorene in extracts of the 2-azoxyfluorene incubations. Extracts of the Congo red incubations were mutagenic toward Salmonella typhimurium TA1538 in the presence of a post-mitochondrial activating system, but Congo red was not mutagenic without this reductive pretreatment. Thus, the utility of the Ames test in screening for potential mutagens may be expanded by a reductive pretreatment utilizing cecal bacteria.

Animals↗

PubMed1996

Congo red-stabilized intermediates in the lambda light chain transition from native to molten state.

Disruption of tertiary interaction makes a protein accessible to penetration by different small molecular compounds. Their interaction may stabilize the altered protein conformation. Congo red is proposed here as a stabilizer of the molten globule state and also of highly reversible intermediates in the transition from native to molten state. Human immunoglobulin lambda light chain (dimer) was used. Two protein-Congo red complexes were found after heating lambda chain in the presence of Congo red. They differed in the amount of attached dye molecules. The binding of dye was interpreted as a two-step dye penetration process involving the peripheral parts of the protein in the first step (at lower temperatures). It was concluded that the liquid crystal properties of Congo red enable it to form specific complexes with proteins, which have become accessible to penetration by ligands after global or local disruption of tertiary interaction. This dye may thus be used as a stabilizer of unfolding intermediates in the step preceding the molten globule state.

Anilino Naphthalenesulfonates↗

PubMed2003

Synthesis and evaluation of analogues of Congo red as potential compounds against transmissible spongiform encephalopathies.

The synthesis of analogues of the amyloid stain Congo red (1) as potential compounds against transmissible spongiform encephalopathies (TSEs) is reported. Using the direct method, aniline (2) or diamines such as 4,4'-diaminodiphenylsulfone (dapsone, 9), 3,3'-diaminodiphenylsulfone (10), benzidine (11), 3,3'-dimethoxybenzidine (12) or 3,3'-dichlorobenzidine (13) were diazotised to afford the corresponding diazonium salts, which without isolation, were directly used for coupling with a range of aromatic sulfonic or carboxylic acids to provide the corresponding truncated dyes analogues of Congo red, 4, 6, 8, and the symmetrical bis azoic dyes 14-19, 21-22, 24 and 26-29 as their sodium salts. Compounds were assayed in a cellular model of scrapie, a sheep TSE. Some of the compounds were shown to have similar activity to the lead compound Congo red. Molecular modelling was carried out to investigate potential structure-activity relationships (SARs) relating to the size and shape of Congo Red analogues. Within the range of compounds tested no discernible SARs were found.

Amino Acids↗

PubMed2002

Factors affecting haemolysin production and congo red binding in Salmonella enterica serovar Typhimurium DT 98.

Differences in haemolysin expression were observed in a strain of Salmonella enterica serovar Typhimurium definitive phage type (DT) 98 cultured under various conditions. Haemolysin expression was optimal in cultures grown micro-aerobically. The zones of haemolysis were wider after longer periods of incubation. Haemolysin production varied after growth in the following media (greatest to least): brain heart infusion (BHI) broth > nutrient broth (NB)>trypticase soy broth (TSB)> M-9 glucose medium. Haemolysin production correlated directly with Congo red binding in nutrient broth. On Congo red blood agar, colonies were smaller, with dark centres and wider zones of haemolysis. Culture-cell-free haemolysin activity was higher, but cell-bound haemolysin activity was very low in growth medium supplemented with Congo red. Boiled tea extract at 25% v/v (of 25% w/v tea infusion) in PBS and nutrient broth was bactericidal to S. Typhimurium DT 98. The addition of boiled tea extract to growth medium inhibited haemolysin production by S. Typhimurium DT 98 at higher concentrations (6-12.5% v/v) but stimulated haemolysin production at lower concentrations (1.5-3% v/v). The pre-treatment of bacterial cell suspensions with lower concentrations of tea extract (1.5-3% v/v) also altered the Congo red binding, which showed an inverse correlation in nutrient broth.

Colony Count, Microbial↗

PubMed1992

Potent inhibition of scrapie-associated PrP accumulation by congo red.

Transmissible spongiform encephalopathies (prion diseases), Alzheimer's disease, and other amyloidoses result in the accumulation of certain abnormally stable proteins that are thought by many to play central roles in disease pathogenesis. Using scrapie-infected neuroblastoma cells as a model system, we found that Congo red, an amyloid-binding dye, potently inhibits the accumulation of the scrapie-associated, protease-resistant isoform of protein PrP without affecting the metabolism of the normal isoform. Growth of the cells with submicromolar concentrations of Congo red for 5 days reduced the amount of protease-resistant PrP detected in the cultures by greater than 90%. This activity of Congo red suggests that it selectively disrupts the conversion of PrP to the protease-resistant isoform or destabilizes this isoform once it is made. Potential therapeutic applications of Congo red are discussed.

Animals↗

PubMed1976

Congo red vital staining of cornea and conjunctiva.

Vital staining with an aqueous solution of 1% Congo red has been studied in the slit lamp. In 98 cases the dye was mixed with 1% lissamine green, in 120 eyes subsequent staining was performed with 0.125% fluorescein, and in 80 cases the mucous thread from the inferior conjunctival fornix was microscoped. Congo red stains dead cells, degenerate cells, and mucus. The dye discloses keratitis, corneal erosion, contact lens damages, corrosions, etc. It stains like lissamine green and rose bengal, though less frequently and less intensely than these. Congo red is a pH indicator. Acid reaction beyond its pH-range (3.0-5.2) has not been demonstrated. Amyloid-specific colour reaction (red-green dichromatic polarisation) has been noticed in mucous fibrils, most often in relation to infectious conjunctivitis and corrosion, never in normal eyes. The phenomenon is believed to indicate degeneration of the mucous fibrils (on the analogy of toluidine-blue-stained mucus), whereas not presence of genuine amyloid. It is, in other words, an important phenomenon in the differential diagnosis. Congo red is hardly indicated in ordinary clinical practice for vital staining of cornea and conjunctiva. Fluorescein, combined with rose bengal or lissamin green should be preferred.

Congo Red↗

PubMed1987

Congo red binding phenotype is associated with hemin binding and increased infectivity of Shigella flexneri in the HeLa cell model.

Wild-type isolates of Shigella flexneri bind the dye Congo red from solid media, thus producing red (Crb+) colonies. Mutants which fail to bind the dye produce white colonies (Crb-) and are avirulent in a variety of systems. In S. flexneri the ability to bind Congo red correlates with the ability to bind hemin and protoporphyrin IX. Binding of hemin by Crb+ S. flexneri was observed both in solid media and in liquid assays. Results of competition experiments suggest that Congo red and hemin bind to the same site on the bacterial cell and are retained on the cell surface. Binding of hemin by Crb+ S. flexneri is independent of hemin transport since both Crb+ and Crb- cells can utilize hemin as a sole source of iron. Both Crb- and Crb- organisms were able to grow in HeLa cell lysates, indicating that the gene(s) that is responsible for Congo red binding does not play a role in the acquisition of intracellular heme iron. By using the HeLa cell invasion system, the effect of hemin prebinding on the invasiveness of Crb+ S. flexneri was determined. Crb+ cells which had prebound hemin exhibited increased invasiveness, indicating a possible role for the crb gene product in the initial stages of invasion by S. flexneri.

Congo Red↗

PubMedDate not supplied

Why Congo red binding is specific for amyloid proteins - model studies and a computer analysis approach.

BACKGROUND: The complexing of Congo red in two different ligand forms - unimolecular and supramolecular (seven molecules in a micelle) - with eight deca-peptides organized in a b-sheet was tested by computational analysis to identify its dye-binding preferences. Polyphenylananine and polylysine peptides were selected to represent the specific side chain interactions expected to ensure particularly the stabilization of the dye-protein complex. Polyalanine was used to verify the participation of non-specific backbone-derived interactions. MATERIAL AND METHODS: The initial complexes for calculation were constructed by intercalating the dye between the peptides in the middle of the beta-sheet. The long axis of the dye molecule (in the case of unimolecular systems) or the long axis of the ribbon-like micelle (in the case of the supramolecular dye form) was oriented parallel to the peptide backbone. This positioning maximally reduced the exposure of the hydrophobic diphenyl (central dye fragment) to water. In general the complexes of supramolecular Congo red ligands appeared more stable than those formed by individual dye molecules. Specific interactions (electrostatic and/or ring stacking) dominated as binding forces in the case of the single molecule, while non-specific surface adsorption seemed decisive in complexing with the supramolecular ligand. RESULTS: Both the unimolecular and supramolecular versions of the dye ligand were found to be likely to form complexes of sufficient stability with peptides. The low stability of the protein and the gap accessible to penetration in the peptide sheet seem sufficient for supramolecular ligand binding, but the presence of positively charged or hydrophobic amino acids may strengthen binding significantly. CONCLUSIONS: The need for specific interaction makes single-molecule Congo red binding rather unusual as a general amyloid protein ligand. The structural feature of Congo red, which enables specific and common interaction with amyloid proteins, probably derives from the ribbon-like self-assembled form of the dye.

Amyloid beta-Peptides↗

PubMed2004

In vivo accumulation of self-assembling dye Congo red in an area marked by specific immune complexes: possible relevance to chemotherapy.

Supramolecular micellar structures have been proposed as carriers in aim-oriented drug transportation to a target marked by specific immune complexes. In this study, the self-assembling dye Congo red was used as a model supramolecular carrier and its accumulation in the target was studied in vivo. The target was created in vivo as the local specific inflammation provoked by subcutaneous injection of antigen to the ear of a previously immunized rabbit. The color caused by accumulation of Congo red after its intravenous injection was registered by pictures of the ear with suitably filtered visible light shining through it to distinguish Congo red against the background color of hemoglobin. The results confirmed the expected accumulation and retention of Congo red in the inflammation area marked by deposits of specific immune complexes. The role of albumin and its possible interference with transportation of drugs through the blood by supramolecular carriers was also subjected to preliminary examination. The results revealed that albumin collaborates rather than interferes with drug transportation; this is another factor making the use of supramolecular carriers for aim-oriented chemotherapy highly promising.

Albumins↗

PubMedDate not supplied

Correlation between Congo red binding as virulence marker in Shigella species and Sereny test.

Six variants of nutrient agar were tested in order to chose the suitable media for Congo red binding test. Trypto-soy Eiken, T.S.A - Cantacuzino Institute and B.T.S.D. (a medium prepared with Difco ingredients) are appropriate to distinguish between virulent Crb+ and avirulent Crb- strains. Congo red binding was compared with Sereny test using 25 Shigella strains. The strains were inoculated onto trypto-soy agar Eiken plates with 0.01% Congo red, incubated 24 hours at 37 degrees C. A number of each kind (Crb+ and Crb-) of colonies developed by every strain was subcultured on nutrient agar and Sereny test was performed with these cultures. As expected, all 84 Crb+ colonies in vivo tested, produced keratoconjunctivitis. In the case of Crb- colonies a proper correlation with Sereny negative test was observed in 57 out of 73 colonies (78.2%) to which 10.9% (8 out of 73) less virulent (evoking illness in only one of the two inoculated eyes) colonies may be added. As our results confirmed that loss of pigmentation was consistently accompanied by loss or diminishing of virulence, we consider that Congo red binding may be used as an alternative of in vivo test for establishing the virulence of Shigellae in the routine practice of microbiology laboratories which usually are not provided with cell cultures or animals. Its reduced cost is an important advantage, too.

Animals↗

PubMed1995

Docking of congo red to the surface of crystalline cellulose using molecular mechanics.

A method for the docking of ligands to crystalline surfaces using molecular mechanics was developed and applied to study the molecular features of the adsorption of Congo Red to cellulose crystals. The docking procedure was based on a grid search exploring the surface repeat unit of the cellulose crystals using several orientations of Congo Red at each grid point. Results suggest a preferential adsorption of Congo Red onto certain faces of the cellulose crystals and that the lower energy conformers have a similar positioning and orientation with respect to the cellulose chains at the surface repeat unit.

Adsorption↗

PubMed1993

Proximal gastric vagotomy and anterior seromyotomy with posterior truncal vagotomy assessed by the endoscopic congo red test.

The completeness of vagotomy following proximal gastric vagotomy or anterior seromyotomy with posterior truncal vagotomy was assessed prospectively in 48 patients using the intraoperative congo red test. Pentagastrin (6 micrograms/kg) was given subcutaneously before the assessment. An endoscope was passed into the stomach and 180 ml congo red solution washed over the gastric mucosa. Continuing acid production was indicated by the appearance of a black colour (pH < 3) 2 min after introduction of the dye. A grading system was adopted where grades I and II showed little black discoloration and grades III and IV showed increasing areas of discoloration indicating that further denervation was required. All 20 patients undergoing anterior seromyotomy with posterior vagotomy were classified as grade I. Fifteen of an initial 23 patients receiving proximal gastric vagotomy were grade III or IV. Following division of either the right gastroepiploic nerve or the posterior vagal trunk, 22 patients improved to grade I (16) or II (six). In the subsequent five proximal vagotomies, modification of the dissection produced grade I results. Anterior seromyotomy with posterior truncal vagotomy gave consistently complete vagotomy. The congo red test highlighted major differences in the adequacy of vagotomy achieved using various dissection techniques during proximal gastric vagotomy. The test is a useful, reproducible and simple intraoperative method for assessing the completeness of denervation.

Adolescent↗

PubMed1994

An electron microscope and electron diffraction study of the effect of calcofluor and congo red on the biosynthesis of chitin in vitro.

The structure of chitin made in vitro by chitin synthetase was studied by electron microscopy and electron diffraction. Two different forms of chitin synthetase from the fungus Mucor rouxii were tested: chitosomes and 16 S particles. The long chitin fibrils produced by chitosomes had a high degree of crystallinity as revealed by electron diffraction. Specimen regions made of largely parallel microfibril bundles produced distinct fiber diagrams, an indication that the chitin chains were aligned along the fibril axis. Microdiffractometry of the shorter chitin crystals synthesized by 16 S particles also showed a similar alignment of chitin chains. Calcofluor and Congo red were powerful inhibitors of chitin synthetase and had profound effects on the color, macroscopic texture, electron microscopic morphology, and crystal structure of the biosynthesized chitin. Chitin made in the presence of Congo red had a bright red color; the one made in the presence of Calcofluor was strongly fluorescent and had a distinctly blue hue when illuminated by daylight. The dyes were tightly bound to the chitin and could not be removed by washing with water or ethanol. At low dye concentration, a mixture of two kinds of crystals was produced by 16 S particles: some were of the same dimensions as those made in the absence of dyes, but others were much thinner. At high dye concentration, there were only thin crystals. With increasing concentrations of Calcofluor or Congo red, the typical electron diffraction reflections of alpha-chitin, particularly the strong equatorial band at 0.466 nm became fainter and a new additional reflection centered at 0.40 nm arose as the dominant feature of the patterns. We regard the gel-like material, synthesized at highly inhibitory dye concentrations, as an apposition complex where the dye does not form part of the crystal structure of chitin and the bulk of the complex consists of molecular stacks of dye associated with nascent chitin chains or narrow chitin microfibrils.

Benzenesulfonates↗

PubMed2000

Inhibition of formation of protease-resistant prion protein by Trypan Blue, Sirius Red and other Congo Red analogs.

Five compounds related to Congo Red were found to inhibit generation of protease-resistant prion protein in a cell-free system. In this assay Trypan Blue, Evans Blue, Sirius Red F3B, Primuline and Thioflavin-S were all more inhibitory than Congo Red itself. In scrapie-infected mouse neuroblastoma cells one compound, Sirius Red F3B, was capable of blocking the formation of protease-resistant prion protein to a similar extent as Congo Red; however, the other four compounds were less effective. Some of these compounds should be considered for testing in TSE disease models in live animals.

Animals↗

PubMed1992

The influence of congo red on the cell wall and (1----3)-beta-D-glucan microfibril biogenesis in Saccharomyces cerevisiae.

Congo red was applied to growing yeast cells and regenerating protoplasts in order to study its effects on wall biogenesis and cell morphogenesis. In the presence of the dye, the whole yeast cells grew and divided to form chains of connected cells showing aberrant wall structures on both sides of the septum. The wall-less protoplasts in solid medium with the dye exhibited an abnormal increase in volume, regeneration of aberrant cell walls and inability to carry out cytokinesis or protoplast reversion to cells. In liquid medium, the protoplasts synthesized glucan nets composed mainly of thin fibrils orientated at random, whereas normally, in the absence of dye, the nets consist of rather thick fibrils, 10 to 20 nm in width, assembled into broad ribbons. These fibrils are known to consist of triple 6/1 helical strands of (1----3)-beta-D-glucan aggregated laterally in crystalline packing. The thin fibrils (c. 4 to 8 nm wide) can contain only a few triple helical strands (c. 1.6 nm wide) and are supposed to be prevented from further aggregation and crystallization by complexing with Congo red on their surfaces. Some loose triple 6/1 helical strands (native elementary fibrils) are also discernible. They represent the first native (1----3)-beta-D-glucan elementary fibrils depicted by electron microscopy. The effects of Congo red on growth and the wall structure in normal cells and regenerating protoplasts in solid medium can be explained by the presence of a complex which the dye forms with (helical) chain parts of the glucan network and which results in a loss of rigidity by a blocked lateral interaction between the helices.

Cell Division↗