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PubMed1998

Plasticity of Congo red staining displayed by subpopulations of neurons within the rat central nervous system.

We document the presence of subpopulations of neurons within the rat central nervous system that are labelled with a new Congo red staining technique. These neurons (CR neurons) show shrunken somata, and smaller and darker nuclei than Congo red-negative cells (non-CR cells). With the Bielschowsky and the cresyl violet Nissl staining methods, two comparable subpopulations of cells can be distinguished by the same morphometrical criteria as those used for CR and non-CR cells. CR neurons are located preferentially in some brain regions while in others they are virtually absent. Their distribution and proportion varied greatly from animal to animal and after particular treatments. Injections of water that damaged the hippocampal dentate gyrus, cortical lesions or eye enucleation decreased the number of CR-cells in the CA1 subfield, reflected in a shift from the CR-staining subclass to the non-CR subclass. Treatment with 200 mg/kg of CDP-choline also significantly reduced the number of CR cells observed in CA1. In the red nucleus, CR neurons showed a characteristic distribution of beta-amyloid precursor protein (APP) immunoreactivity. The population of dendrites immunolabelled for microtubule-associated protein 2 was markedly decreased in the areas of the hippocampus with high numbers of CR cells. Therefore, it is proposed that neurons labelled with the present Congo red technique might be in a reversible degenerative state or represent a particular physiological state in some areas of the central nervous system.

Amyloid beta-Protein Precursor↗
PubMed2003

Genetic diversity in the coat protein coding region of eighty-six sugarcane mosaic virus isolates from eight countries, particularly from Cameroon and Congo.

Fifty-eight sugarcane virus isolates were obtained from leaves showing mosaic symptoms, and collected in Cameroon (26 isolates), Congo (20 isolates), Egypt (1 isolate), South Africa (3 isolates) and the U.S.A. (8 isolates). All these isolates belonged to Sugarcane mosaic virus (SCMV) based on the amplification product obtained by RT-PCR with SCMV-specific primers. The amplicons (0.9 kb) from the coat protein (CP) coding region were cloned, sequenced and compared to each other as well as to the sequences (GenBank accessions) of 16 SCMV isolates from sugarcane (Australia, South Africa and U.S.A.) and 12 SCMV isolates from maize (Australia, Germany and China). Maximum likelihood and maximum parsimony analyses robustly supported two major monophyletic groups that were correlated with the host of origin: the SCE or sugarcane group that included all isolates from sugarcane and the MZ or maize group that contained all isolates from maize. The 86 virus isolates were distributed in 13 minor phylogenetic groups, four (I-IV) restricted to maize and nine (V-XIII) to sugarcane. A strong correlation was observed between the sugarcane groups and the geographical origin of the SCMV isolates. Each SCMV type strain from sugarcane (A, B, D, E and SC) was distributed in a different phylogenetic group or subgroup. The 26 isolates from Cameroon constituted a relatively homogeneous group (group V) whereas the 20 isolates from Congo belonged to two other groups (VI and VII). All the isolates from Cameroon and Congo were different from the SCMV type strains and other strains or isolates studied so far. It appears, therefore, that the population of SCMV from sugarcane in Africa contains virus genotypes that have not yet been described.

Cameroon↗
PubMed1992

Prospective comparison of congo red and sham feeding testing to determine vagal innervation of the stomach.

The purpose of this study was to validate Congo red (CR) testing as a means of determining the status of vagal innervation of the stomach after gastric surgery by comparing it with the sham feeding test (SF). Twenty-six patients with previous gastric operations were studied prospectively. The operations were vagotomy/antrectomy (n = 14), vagotomy/antrectomy/Roux-en-Y anastomosis (n = 4), proximal gastric vagotomy (n = 3), vagotomy/pyloroplasty (n = 2), and antireflux (n = 3). In each case, the CR test was performed prior to the SF test so that the endoscopist was unbiased. The CR test solution was sprayed on the gastric mucosa through a wash catheter and immediately aspirated. A two-dimensional map of the endoscopist's conception of the red and black mucosa was drawn, and areas were calculated using a computerized scanner. The SF test was performed as described previously, with sham/peak ratios (sham feeding stimulated acid output [SAO]/peak acid output [PAO]) greater than 0.1 indicating a positive test, or incomplete vagotomy. The CR test was negative in 11 patients and positive in 15 patients. SF was negative in 16 patients (SAO/PAO of less than 0.1) and positive in 10 patients. The results correlated in 18 of 26 (69%) patients (p = not significant). Positive sham feeding tests and negative Congo red tests were more reliable, whereas negative sham feeding tests and positive Congo red tests were less reliable. Except patients with Roux-en-Y anastomosis, patients with negative or weakly positive CR tests did not have recurrent ulcers or other symptoms attributable to acid hypersecretion. The CR test was easier to perform and preferred by the patients. We conclude that both tests provide valuable clinical information and that both tests should be available in the evaluation of postgastrectomy patients.

Anastomosis, Roux-en-Y↗
PubMed2006

Regional differences in the recovery of gastric acid secretion after Helicobacter pylori eradication: evaluations with Congo red chromoendoscopy.

BACKGROUND: Gastric-acid secretion is reduced in Helicobacter pylori-positive fundic atrophic gastritis, but it is restored by the eradication. However, changes in the distribution of acid-secreting mucosa after the eradication remain unknown. Congo red chromoendoscopy is capable of visualizing the acid-secreting fundic mucosa. OBJECTIVE: To evaluate the effect of H pylori eradication on the distribution of acid-secreting mucosa in the fundus by using Congo red chromoendoscopy. DESIGN: An assessment of the distribution of acid-secreting mucosa by the visualized images of Congo red chromoendoscopy and a histologic evaluation of biopsy specimens were performed before and 1 and 7 months after the eradication. The areas of the acid-secreting mucosa in the lesser and greater curvatures of the fundus were evaluated semiquantitatively. PATIENTS: Thirty-seven patients positive for H pylori and with fundic atrophic gastritis. RESULTS: The area of the acid-secreting mucosa increased in 27 cases (73%) by 1 month after eradication, and in 32 cases (86%) by 7 months. This expansion of the acid-secreting mucosa coincided with the improvement of inflammatory changes rather than with that of the mucosal atrophy and was more prominent on the greater curvature than on the lesser curvature. CONCLUSIONS: The acid-secreting mucosa in the fundus expanded in most cases with fundic atrophic gastritis after H pylori eradication, which could be responsible for the increase in acid secretion after the treatment. Regional differences in the recovery of local acid secretion may be associated with site-specific susceptibility to the development of gastric cancer after successful eradication.

Aged↗
PubMed2006

Prion urine comprises a glycosaminoglycan-light chain IgG complex that can be stained by Congo red.

Light chain IgG, a known amyloidotic protein, is present in the urine of prion disease affected individuals in a protease resistant form. In addition, it was shown recently that prion urine samples comprise a significant excess of glycosaminoglycans. Since amyloidotic proteins and glycosaminoglycans are the major components of amyloid aggregates, a Congo red dot blot assay was developed for detection of Creutzfeldt-Jacob disease (CJD) in urine. This assay was also positive for about 10% of patients suffering from diseases such as Alzheimer disease, cerebrovascular attacks and multiple sclerosis, but negative for healthy controls. Both glycosaminoglycans and proteins such as light chain IgG were required for the binding of Congo red to the urine fractions, as shown by the fact that Proteinase K digestion of the samples either after guanidine or after choindrotinase abolished the Congo red signal from the CJD samples.

Carrier Proteins↗
PubMed2000

The conformational characteristics of Congo red, Evans blue and Trypan blue.

The structures of the closely related bis-azo dyes Evans blue, Trypan blue and Congo red, which appeared to have different self-assembly properties and correspondingly different abilities to form complexes with amyloids and some other proteins, were compared in this work. Ab initio and semi-empirical methods were used to find the optimal structures and partial charge distributions of the dyes. The optimal structures were searched using different widely used programs. The structures of Congo red and evans blue were found to be planar, except for the torsion on the central diphenyl bond connecting the two halves of the dye. Both symmetrical parts of the molecules appeared very close to planarity. However, Trypan blue exhibits non planarity on the di-azo bonds, as well as on the central bond between the symmetrical parts of the dye. In a consequence, the non planarity of this molecule is higher than in the case of its isomer, Evans blue and Congo red as well. The extra rotation around the azo bonds extorted by the close proximity of the sulfonic groups may be the direct cause of its poor self-assembling and complexation properties versus Evans blue.

Coloring Agents↗
PubMed2003

Detection of immunoglobulin G to Crimean-Congo hemorrhagic fever virus in sheep sera by recombinant nucleoprotein-based enzyme-linked immunosorbent and immunofluorescence assays.

Crimean-Congo hemorrhagic fever virus is a tick-borne virus that causes severe hemorrhagic symptoms with an up to 50% mortality rate in humans. Wild and domestic animals, such as sheep, cattle and goats, are the reservoirs. The recombinant nucleoprotein-based Crimean-Congo hemorrhagic fever virus antibody detection systems for sheep sera were developed by enzyme-linked immunosorbent assay (ELISA) and an indirect immunofluorescence assay techniques. The samples used for evaluation were 80 sera collected from sheep in a Crimean-Congo hemorrhagic fever-endemic area (western part of the Xinjiang Uygur Autonomous Region) and 39 sera collected from sheep in a disease-free region (Shandong province, eastern China). The ELISA and indirect immunofluorescence assay using recombinant nucleoprotein of the virus proved to have high sensitivity and specificity for detecting the immunoglobulin G antibodies to the virus in sheep sera. Within this limited number of samples, the recombinant nucleoprotein-based ELISA and indirect immunofluorescence assay are considered to be useful tools for seroepidemiological study of virus infections in sheep sera.

Animals↗
PubMed1980

A strain marker in Rhizobium trifolii based on the absorption of congo-red.

It is widely recognized that most rhizobia absorb congo-red weakly when grown on agar media containing this dye. In contrast to this generalized behaviour, an ineffective strain of Rhizobium trifolii (Coryn) has been found which strongly absorbs the dye, producing growth of a very deep-red colour on yeast-extract mannitol agar, supplemented with congo-red (0.025 g/l). Assays for dye absorption characteristics on this medium with 21 strains of R. trifolii showed that Coryn could be readily differentiated from all the other strains examined. Supplementary fluorescent antibody tests with Coryn confirmed the reliability of differential absorption of congo-red as a strain-marker system. Data are presented which demonstrate the potential of this characteristic as a strain identification method in nodulation and competition studies under aseptic growth conditions, using mixed inocula.

Absorption↗
PubMed2005

Spectroscopic studies of the intermolecular interactions of Congo red and tinopal CBS with modified cellulose fibers.

The adsorption of Congo red and tinopal CBS dyes on cellulose fibers was investigated using electronic absorption and fluorescence spectroscopies. Hydrogen bonds appear to be relevant for the dye-fiber interactions as indicated by the solvatochromism of Congo red in water, methanol, and dimethyl sulfoxide solutions, and when adsorbed on cellulose fibers. We also demonstrate that electrostatic interactions play an important role in the dye-medium interaction, through the analysis of absorption spectra of Congo red and fluorescence spectra of tinopal in aqueous solutions containing salt and in layer-by-layer nanostructured films with poly(allylamine hydrochloride). For instance, dye adsorption was enhanced when salt was added to the dipping solution, which was explained by the synergistic effect between the conformational changes of the cellulose and changes in the solvation layer around the cellulose chains and around dye molecules. On the basis of the fluorescence results for tinopal CBS, we inferred that dye aggregation is not relevant for adsorption on the fibers. In addition, fluorescence spectroscopy is proven very sensitive for studying the organization of dye molecules in layer-by-layer films, particularly those undergoing irreversible structural changes.

Benzenesulfonates↗
PubMed2004

Force-field parametrization and molecular dynamics simulations of Congo red.

Congo red, a diazo dye widely used in medical diagnosis, is known to form supramolecular systems in solution. Such a supramolecular system may interact with various proteins. In order to examine the nature of such complexes empirical force field parameters for the Congo red molecule were developed. The parametrization of bonding terms closely followed the methodology used in the development of the charmm22 force field, except for the calculation of charges. Point charges were calculated from a fit to a quantum mechanically derived electrostatic potential using the CHELP-BOW method. Obtained parameters were tested in a series of molecular dynamics simulations of both a single molecule and a micelle composed of Congo red molecules. It is shown that newly developed parameters define a stable minimum on the hypersurface of the potential energy and crystal and ab initio geometries and rotational barriers are well reproduced. Furthermore, rotations around C-N bonds are similar to torsional vibrations observed in crystals of diphenyl-diazene, which confirms that the flexibility of the molecule is correct. Comparison of results obtained from micelles molecular dynamics simulations with experimental data shows that the thermal dependence of micelle creation is well reproduced.

Biphenyl Compounds↗
PubMed1988

Diagnosis of simultaneous multiple gastric cancers by the endoscopic Congo red--methylene blue test.

The clinicopathological features of simultaneous multiple gastric cancers, and the accuracy of their diagnosis by routine endoscopic examination were analyzed. In addition, the accuracies of diagnosis of coexisting early gastric cancers by routine endoscopic examination and by the endoscopic Congo red--methylene blue test developed in our hospital were compared. The results showed that multiple cancers occurred frequently in elderly male patients, in patients with early gastric cancer of the flat and elevated types and the depressed type without converging folds, and in patients with advanced cancer of Borrmann type I. These patients frequently have early cancers of the flat or depressed types without converging folds, and advanced cancers of Borrmann type I. The coexisting lesions are very difficult to diagnose by routine endoscopic examination: a correct diagnosis of coexisting early cancers was made in only 28.3% of the cases by routine endoscopic examination. But with the Congo red--methylene blue test, the diagnostic rate was raised significantly to 88.9%. In this test, Congo red and methylene blue are sprayed on the surface of the stomach and are bleached within 2 to 5 minutes on the surface of a tumor, but not on the surface of unaffected mucosa.

Aged↗
PubMed1984

Diagnosis of early gastric cancers in the upper part of the stomach by the endoscopic Congo red-methylene blue test.

The clinicopathological features of the early gastric cancers in the upper part of the stomach, and the accuracy of their diagnosis by routine endoscopic examination were examined, and the accuracy of diagnosis of minute and flat cancers in the upper portion of the stomach by routine endoscopic examination and by the endoscopic Congo red-methylene blue test developed in our clinic were compared. Early cancers in the upper part of the stomach occurred in the elderly patient, and grossly elevated types were frequent. Endoscopically they were most difficult to diagnose by a single routine endoscopic examination, because they were frequently overlooked, and adequate biopsy was difficult in some cases. A correct diagnosis of minute and flat cancers in the upper part of the stomach by routine examination was made in only 27.3% and 25.0% of the cases, respectively. But with the Congo red-methylene blue test the diagnostic rate was raised significantly to 75.0% and 83.3%, respectively. In this test, Congo red and methylene blue sprayed on the surface of the tumor were bleached white 2 to 5 minutes after application, in sharp contrast to the unaffected mucosa.

Adenocarcinoma↗
PubMed2001

Saving the gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) of the Congo Basin.

The forests of the Congo Basin in equatorial Africa are home to significant populations of gorillas and chimpanzees. However, numbers are declining owing to hunting and to alteration of their habitat. Gorillas and chimpanzees are particularly vulnerable for biological reasons: slow reproduction, prolonged developmental periods and complex social behaviour. In addition, their capacity to recover from disturbance is limited and the reinforcement of wild populations with captive-born individuals is rarely an option. Compared with the critically endangered mountain gorillas and the beleaguered chimpanzees in forest fragments in West Africa, there are some reasons for optimism about the future of the Congo Basin apes: levels of threat remain relatively low; and conservation of tropical rainforests has become a priority of the international community. At the same time, knowledge of the ecological needs of wild apes has increased and non-invasive techniques now exist to monitor population health. Sadly, no animals remain truly 'wild', as their survival depends to a greater or lesser extent on management. Protected areas and laws that forbid hunting of vulnerable species are classic tools of management, but broader landscape visions are now emerging that may allow the Congo Basin to avoid the fragile scenario of larger animals persisting only in 'island' parks.

Animals↗
PubMed2000

Genetic subtypes of HIV type 1 in Republic of Congo.

To assess the molecular epidemiology of HIV-1 in Republic of Congo (Congo), we investigated 29 HIV-1s obtained from 82 Congolese AIDS and ARC patients in 1996 and 1997. Part of the env region including the V3 loop was phylogenetically analyzed. The genotypes observed were varied: of 29 specimens, 12 (41 %) were subtype A, 1 (3%) was subtype D, 6 (21%) were subtype G, 6 (21%) were subtype H, 2 (7%) were subtype J, and 2 (7%) could not be classified as any known subtypes (U, unclassified). The heterogeneous profile of HIV-1 infection was different from the profiles of neighboring Central African countries. These data show that subtypes G and H as well as subtype A were circulating with high prevalence. The fact that new genetic subtypes (J and U) are circulating indicates a need for a greater surveillance for these subtypes both in Congo as well as in other parts of the world.

AIDS-Related Complex↗
PubMed2002

Genetic subtypes of HIV type 1 based on the vpu/env sequences in the Republic of Congo.

To investigate the HIV-1 subtypes prevalent in the Republic of Congo, we isolated 28 HIV-1 strains from Congolese AIDS patients in 1996 and 1997, and analyzed them phylogenetically. Phylogenetic analysis based on part of the 5' tat-env (vpu) and env sequences revealed that only 13 (46.4%) of the 28 isolates belonged to the same subtype in the vpu tree as in the env tree; the remaining 15 (53.6%) strains showed discordant subtypes between vpu and env with 6 different profiles; that is, 1 A/A (vpu/env), 1 D/D, 5 G/G, 4 H/H, 2 unclassified (U)/U, 9 G/A, 2 G/H, 1 G/J, 1 H/G, 1 U/A, and 1 U/J. Thus, 9 of the 15 discordant HIV-1s were of the G/A (vpu/env) type, and did not form any subcluster within the subtype G lineage in the vpu-based phylogenetic tree. In addition, CRF02_AG (IbNG), which is a G/A (vpu/env) type, was not found in the Republic of Congo. These data suggest that the majority of HIV-1 subtypes circulating in the Republic of Congo have mosaic structures and may have been derived from independent recombinational events.

5' Untranslated Regions↗
PubMed1999

Growth of children according to maternal and child HIV, immunological and disease characteristics: a prospective cohort study in Kinshasa, Democratic Republic of Congo.

BACKGROUND: Most HIV-infection in children occurs in sub-Saharan Africa where antiretroviral therapy is seldom available. This study compares the growth progression and retardation of HIV-infected and uninfected children in the Democratic Republic of Congo (formerly Zaire). It estimates the risk for child growth retardation according to child and maternal immunological factors, severity of maternal and child illness, and maternal socioeconomic and marital status. METHODS: In a prospective cohort study of 258 children born to HIV seropositive mothers and 256 children of seronegative mothers in Kinshasa, Congo, the growth in length, weight, and weight-for-length of infected children (n = 68), uninfected children born to seropositive mothers (n = 190), and uninfected children born to uninfected mothers (n = 256) was compared. Serological, anthropometric and other clinical measures were collected monthly from 3-12 months and bi-monthly during the second year of life. Polymerase chain reaction for HIV was performed on bloods drawn at 2 days and 3 months post partum. Length-for-age, weight-for-age, and weight-for-length mean z-scores against National Center for Health Statistics (NCHS) reference data were calculated, and Cox proportional hazards models were used to estimate the risk of falling below -2.00 z-scores as a function of child and maternal immunological, clinical and sociodemographic variables. RESULTS: There was no difference in mean length-for-age at birth between HIV-infected (Group 1) children, uninfected children of infected mothers (Group 2) or Control children, but by 3 months old, HIV-infected children were shorter than both Group 2 and Controls. In weight-for-age and weight-for-length, Group 1 infants were lighter and more wasted at birth and onwards. Group 2 newborns were lighter than Controls at birth, but by three months they had caught up to Controls in both length and weight and remained the same as Controls thereafter. The odds of falling below -2.00 z-scores by 20 months for length, weight, and weight-for-length for HIV-infected children compared to uninfected children were 2.10, 2.84, and 2.56 respectively. Both HIV-infection and associated illnesses were factors associated with child stunting, underweight and wasting. The mother's age, socioeconomic status, presence of father, stage of illness and immune status had no detectable effect on the child's growth in the first two years of life. CONCLUSION: The HIV-infected children in Congo with no access to antiretroviral therapy were stunted, underweight, and wasted compared to same age uninfected children. Both HIV infection and HIV-associated signs and symptoms, not maternal immunological or socioeconomic circumstances, placed children at risk for growth retardation.

Adult↗
PubMed1986

Influence of the virulence plasmid and the Congo red reaction on the antimicrobial susceptibility of Yersinia species.

Seventeen strains of Yersinia enterocolitica and related species were examined for their susceptibility to a variety of antimicrobial agents. Twelve of the strains were clinical isolates which carried a virulence plasmid; five were food isolates which lacked plasmids. When grown on agar containing Congo red or haemin, each strain yielded pigmented (CR+) and non-pigmented (CR-) variants. CR+ bacteria of clinical origin were virulent, whereas CR+ food isolates and all CR- bacteria were avirulent. The susceptibility of CR+ and CR- bacteria to the following agents was compared: ampicillin, chloramphenicol, latamoxef, nalidixic acid, novobiocin, polymyxin B, rifampicin, streptomycin, tetracycline and tobramycin. The results showed that bacteria which bound Congo red were more susceptible to each drug examined than their CR- counterparts. This relationship held regardless of whether the CR+ bacteria possessed a virulence plasmid or not. The findings suggest that binding of antimicrobial agents by yersiniae may parallel binding of haemin and Congo red.

Anti-Bacterial Agents↗
PubMed1994

Congo red protects against toxicity of beta-amyloid peptides on rat hippocampal neurones.

beta-Amyloid peptides are neurotoxic when applied to primary cultures of hippocampal neurones from the embryonic rat. This neurotoxic effect can be inhibited completely by certain disazo dyestuffs. The most potent of these are Congo Red and Congo Rubin, whilst Direct Garnet and sodium 4-aminonaphthalene-1-sulphonate are inactive. Congo Red also inhibits the neurotoxic effects of the human pancreatic amyloidogenic peptide amylin. It is postulated that these dyes, by interacting with the beta-pleated sheet structure of amyloidogenic peptides, prevent aggregation and hence neurotoxity.

Amyloid↗