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PubMed2003

Profile of eye lesions and vision loss: a cross-sectional study in Lusambo, a forest-savanna area hyperendemic for onchocerciasis in the Democratic Republic of Congo.

OBJECTIVE: To determine baseline data regarding eye lesions and vision loss in five villages of Lusambo, an onchocerciasis-hyperendemic forest-savanna area in the Democratic Republic of Congo (DRC), in preparation of mass ivermectin distribution. METHODS: Five villages were selected by simple randomization. Through a cross-sectional design, 750 subjects were examined ophthalmologically. The eye examination included acuity visual measurement, slit-lamp examination, ophthalmoscopy, intraocular pressure measurement, and visual field assessment by the Wu-Jones test. RESULTS: There was a high prevalence of onchocerciasis-related eye lesions compared with non-onchocercal lesions. Chorioretinitis (20%) was the most frequent disease, others were punctate keratitis and microfilariae in the anterior chamber in equal frequency (13.8%), white intraretinal deposits (10.4%) and iridocyclitis (8%). Vision loss was discovered in 8.5% of the subjects, of whom 0.5% had bilateral blindness, 2.2% had monocular blindness and 5.7% had visual impairment. Vision loss was mostly caused by onchocerciasis-related diseases, especially those affecting the anterior segment of the eye. CONCLUSION: Features of ocular onchocerciasis usually described in forest and savanna areas were both found in this forest-savanna zone of the DRC.

Adolescent↗
PubMed2003

Assessing the efficacy of chloroquine and sulfadoxine-pyrimethamine for treatment of uncomplicated Plasmodium falciparum malaria in the Democratic Republic of Congo.

We evaluated the in vivo responses to chloroquine (CQ), the first line antimalarial, and to sulfadoxine-pyrimethamine (SP), the most readily available and affordable alternative treatment, in children under 5 with acute uncomplicated Plasmodium falciparum malaria in seven sites of Democratic Republic of Congo (DRC) between May 2000 and November 2001, using the standard 14-day WHO protocol. In the CQ group, the overall treatment failure rate was 45.4% (95% CI: 40.1-50.8) of 350 infections successfully tested; in the SP group it was 7.5% (95% CI: 5.0-11.0) of 333 infections. Of 191 patients who had an adequate clinical response (ACR) in the CQ group, 127 (66.5%; range: 62.5-71.4) still had parasitaemia on day 14. In the SP group, only 21 (6.8%; range: 2.2-12.8) of 308 patients with an ACR were still parasitaemic on day 14. Using pooled data from three rural sites, haematological recovery was better in the SP group (mean of haematocrit difference between days 14 and 0 among anaemic children: 4.7 vs. 3.2; P < 0.01, Wilcoxon test). These findings suggest that CQ is no longer effective in DRC and that SP may be a good alternative for its replacement as first line antimalarial treatment. The Ministry of Health (MOH) therefore now recommends SP as the first line antimalarial drug in DRC, as an interim step, 18 months after launching the first study. Additional studies are needed to select alternative therapies that might replace SP or improve its efficacy, should it prove ineffective in the future.

Antimalarials↗
PubMed1998

Structural aspects of Congo red as an inhibitor of protease-resistant prion protein formation.

Congo red (CR) has been shown to inhibit the accumulation in scrapie-infected cells of prion protein (PrP) in the abnormal protease-resistant form (PrP-res). However, it was not clear if this effect was due to a direct interaction of CR with either PrP-res or its protease-sensitive precursor (PrP-sen) or to a less direct effect on living cells. Here we show that CR inhibits PrP-res formation in a simple cell-free reaction composed predominantly of purified PrP-res and PrP-sen. Structurally modified CR analogues were also compared in both the cell-free conversion reaction and scrapie-infected neuroblastoma cells. Methylation of the central phenyl groups at the 2,2' positions diminished the inhibitory potency by > or = 10-fold. In contrast, there was little effect of 3,3' methylation of the phenyls, deletion of one phenyl, or addition of an amido group between the phenyls. The relative activities of these compounds were well correlated in both cellular and acellular systems. Molecular modeling indicated that CR and 3,3'-methyl-CR have little rotational restriction about the biphenyl bond and can readily adopt a planar conformation, as can phenyl-CR and amido-CR. In contrast, 2,2'-methyl-CR is restricted to a nonplanar conformation of the biphenyl group. Thus, planarity and/or torsional mobility of the central phenyl rings of CR and its analogues is probably important for inhibition of PrP-res formation. On the other hand, variations in the intersulfonate distance in these molecules had little effect on PrP-res inhibition. These results indicated a high degree of structural specificity in the inhibition of PrP-res formation by CR and related compounds.

Animals↗
PubMed2000

Effect of Congo red on wild-type and mutated prion proteins in cultured cells.

Transmissible spongiform encephalopathies form a group of fatal neurodegenerative disorders that have the unique property of being infectious, sporadic, or genetic in origin. Although some doubts remain on the nature of the responsible agent of these diseases, it is clear that a protein called PrP(Sc) (which stands for the scrapie isoform of the prion protein) has a central role in their pathology. PrP(Sc) represents a conformational variant of a normal protein of the host: the cellular isoform of the prion protein, or PrP(C). Compounds such as glycosaminoglycans and Congo red (CR) have been shown to interfere with both in vitro and in vivo PrP(Sc) formation. It was hypothesized that CR acts by overstabilizing the conformation of PrP(Sc) molecules or by modifying trafficking of PrP(C). Using transfected cells expressing 3F4-tagged mouse PrPs, we show here that CR does not interfere with conversion of PrP molecules carrying pathogenic mutations. On the contrary, after incubation with the drug, some of their properties, such as insolubility and protease resistance, are enhanced and are even acquired by the wild-type molecule. This last observation suggests an alternative mechanism of action of CR and leads us to reconsider the relationship between the biochemical properties of PrP and conformational alteration of the protein.

Animals↗
PubMed2003

Congo red-positive cardiac kappa-AL amyloidosis in plasmacytoma -- case report and review of the literature.

We report on a 51-year-old female patient who was diagnosed in 2001 as suffering from plasmacytoma. The patient had had complaints of bilateral carpal tunnel syndrome in 1999, treated by a simple dissection without performing histological examination. Congestive heart failure had gradually developed since that time. In 2001 echocardiography revealed a pronounced thickening of the left ventricular wall with systolic and diastolic dysfunction. A kappa-light chain M component and kappa-light chain-restricted bone marrow plasmacytosis were detected. Amyloid deposits staining positive in the kappa-light chain-restriction analysis were observed in a gastric biopsy. Taking into consideration all these findings, a plasmacytoma-associated systemic AL amyloidosis was diagnosed. Cyclophosphamide/prednisolone chemotherapy regimen led to complete haematological remission. Cardiac transplantation, combined with autologous peripheral blood stem cell graft, was considered as the next therapeutic step, but the patient died while on the waiting list for transplantation. Autopsy detected a highly hypertrophic myocardium with narrowed heart cavities. Microscopic examination revealed dense, pink, acellular, Congo red-staining and kappa-immunoperoxidase-positive AL amyloid masses splitting the cardiomyocytes. The present case is remarkable as it demonstrates that carpal tunnel syndrome and congestive heart failure could be symptoms of plasma cell dyscrasia-associated amyloidoses.

Adult↗
PubMed2004

Evaluation of anti-prion activity of congo red and its derivatives in experimentally infected hamsters.

Among transmissible spongiform encephalopathies (TSE), particularly dreadful are the bovine spongiform encephalopathy (BSE), because of its epidemic character, and the new variant of Creutzfeldt-lakob disease (vCJD) in man, possibly related to BSE prion, through the intake of infected food. To treat TSE, many potentially therapeutic agents have been tested: some of them, among which is Congo Red (CAS 573-58-0, CR), delayed the onset of symptoms in scrapie-infected rodents, and some CR derivatives proved to be effective in vitro. The capacity of a synthesized CR derivative (CR-A) and of the aromatic central benzidine rings of CR (CR-B) to abrogate scrapie-induced disease in experimentally infected hamsters was assayed. CR, used as reference substance, administered i.c. after pre-incubation with the scrapie inoculum, was strongly effective in slowing the progression of the infection, while both CR-A and CR-B, administered alone or together, were not effective. Both CR-A and CR, when administered by subcutaneous route in i.c. scrapie-infected animals. prolonged the survival time in comparison to controls; CR-B was not effective. Moreover, both CR and CR-A were very effective in prolonging the survival time of i.p. scrapie-infected hamsters. The hypothesis of possible different mechanisms of interaction between CR or CR-A and the scrapie agent related to the chemical structures of the molecules is discussed.

Animals↗
PubMed2003

In vitro evaluation of the anti-prionic activity of newly synthesized congo red derivatives.

"Transmissible Spongiform Encephalopathies" (TSE) are a group of degenerative progressive fatal disorders of the CNS, affecting both humans and animals. The main pathogenic event is the conversion of cellular prion protein from the normal, enzyme-sensitive (PrPsen), to the insoluble proteinase K-resistant isoform (PrPres). Since the new juvenile variant of Creutzfeldt-Jakob disease (vCJD) is probably due to the transmission of Bovine Spongiform Encephalopathy (BSE) prion protein to man, therapeutic and preventive compounds for animals and humans are urgently needed. Congo Red (benzidine-diazo-bis-1-naphthylamine-4-sulfonic acid sodium salt, CAS 573-58-0, CR), an azoic dye that inhibits amyloid deposition, and some newly synthesized derivatives, more lipophilic and less toxic, were tested for their anti-prionic activity, in different experimental models. Cell-free experiments using the synthetic peptide PrP 106-126, homologous to amino acid residues 106-126 of the human PrP, were run to determine the anti-amyloidogenic properties of some of the molecules. Peptide solutions containing each compound were incubated at 37 degrees C, for increasing times, to analyse the kinetics of aggregation of PrP 106-126 peptide. After incubation, the amount of non-aggregated peptide was measured by RP-HPLC. While CR enhanced the amyloidogenicity of PrP 106-126, derivatives "1a" and "1b" both showed the opposite behaviour, reducing aggregation by 15-20%. In other experiments using electron microscopy PrP 106-126 was assayed with the same molecules to assess the number and size of fibrils formed. CR showed its typical interaction, producing amyloid aggregates, "1a" did not interfere with fibril formation, while "1b" seemed to partially affect the structure of PrP 106-126 fibrils. Using a different cell-free model, it was investigated whether CR derivatives could reverse the protease-resistant PrPres, extracted from Syrian hamster infected brain, into the normal protease sensitive PrPsen. Samples containing fixed amounts of PrPres were incubated at 37 degrees C for 1 h with all the newly synthesized molecules, at concentrations ranging from 50 micrograms/mL to 750 micrograms/mL. After treatment with proteinase K, half of each sample was incubated with 3 mol/L guanidine thiocyanate in order to exclude over-stabilisation of the PrPres aggregates already observed with CR. The remaining amount of PrPres was assessed by Enhanced Chemoluminescence (ECL) Western blotting analysis. None of the compounds induced the reversion of PrPres to PrPsen; nevertheless, 6 of the 8 molecules interacted with PrPres molecules, over-stabilising the PrPres aggregates, from this aspect being similar to CR in activity. Finally, the inhibition of the generation of PrPres in the S12 clone of a mouse neuroblastoma cell line (N2a S12), persistently infected by the mouse adapted Chandler strain of scrapple, was evaluated. Increasing amounts of CR, "1a" and "1b" were added to the culture medium at each cell passage. After various days of treatment, the cells were collected, lysed, and the amount of PrPres was assayed by ECL Western blotting after PK treatment. As expected, there was a decrease in pathological PrP expression starting from the 4th day of treatment, with 5 and 10 micrograms/mL CR; PrPres completely disappeared after respectively 10 and 14 days of treatment. "1a" was strongly effective after 3 days of treatment at 5 and 10 micrograms/mL, but it was also highly toxic; at the concentration of 1 microgram/mL, it had a mild inhibitory effect after 8 days. The reduction of PrPres was also evaluated by intracytoplasmic flow-cytometry immunofluorescence on CR- and "1a"-treated N2a S12 cells. CR induced a dose-related decrease of PrP expression from day 3 to 13 of treatment. At the concentrations of 2 and 1.5 micrograms/mL "1a" also strongly affected the expression of PrP starting from the 3rd day of treatment until the end of the experiment (day 13). These results confirm the importance of using an integrated system, based on different experimental models, to obtain useful information on the mechanism of action of anti-prionic compounds.

Amino Acid Sequence↗
PubMedDate not supplied

[Dermatitis and eosinophilia in a 9-year-old girl from Congo: putative onchodermatitis].

Onchocercosis or riverblindness, caused by the filaria ochnocerca volvulus, is endemic in many countries of central and Western Africa. Symptoms of the disease can occur years after the infection, chronic itching dermatitis is the first sign, without treatment blindness may develop after years. Onchodermatitis is a hyperreactive course of onchocercosis with massive eosinophilia and elevated IgE, which suppresses a microfilarial spread through the body. Here, we report about the case of an 9-year-old girl who immigrated from the republic of Congo at the age of seven and has been living in Germany for more than two years. Presumably she suffered from onchodermatitis. She presented papular, indurated and itching skin lesions with pigmentary changes, predominantly located at the limbs. Remarkable results of blood tests were 11,000/microl (60 %) eosinophils and IgE 28 000 KU/l, ECP > 200 mg/l, without a history of atopic diseases. HIV, Strongylosis and Loa Loa were excluded. Anti filaria antibodies were detected in a concentration of 51 AKE, microscopy of skin samples failed to detect the parasites. After a single dose of Ivermectin the dermatitis improved, after two weeks the itching was absent, results of repeated blood tests tend to normalize in the following months. Due to the long lifespan of filaria in humans, the disease occurs years after infection in endemic areas. The differential diagnosis for itching skin lesions with high eosinophils in children from developing countries should include onchocercosis.

Animals↗
PubMed1982

Heterotopic gastric mucosa in the duodenum - reaction to Congo red under fiberscopic observation.

A 64-year-old woman had gastric heterotopic of the duodenal bulb without any specific complaints. The lesion with irregular excrescence was diagnosed by means of target biopsies through endoscopy, and 3 years later, no noteworthy changes were observed in the endoscopic findings of the lesion, and it was also proved by an endoscopic Congo red test that the excrescence had a function of acid output. This is the second report of congenital heterotopic gastric mucosa of the duodenum which was confirmed not only by histological, but also functional examination.

Child↗
PubMed1997

Heparin-binding properties of the amyloidogenic peptides Abeta and amylin. Dependence on aggregation state and inhibition by Congo red.

Aggregation and deposition of the 40-42-residue amyloid beta-protein (Abeta) are early and necessary neuropathological events in Alzheimer's disease. An understanding of the molecular interactions that trigger these events is important for therapeutic strategies aimed at blocking Abeta plaque formation at the earliest stages. Heparan sulfate proteoglycans may play a fundamental role since they are invariably associated with Abeta and other amyloid deposits at all stages. However, the nature of the Abeta-heparan sulfate proteoglycan binding has been difficult to elucidate because of the strong tendency of Abeta to self-aggregate. Affinity co-electrophoresis can measure the binding of proteoglycans or glycosaminoglycans to proteins without altering the physical state of the protein during the assay. We used affinity co-electrophoresis to study the interaction between Abeta and the glycosaminoglycan heparin and found that the aggregation state of Abeta governs its heparin-binding properties: heparin binds to fibrillar but not nonfibrillar Abeta. The amyloid binding dye, Congo red, inhibited the interaction in a specific and dose-dependent manner. The "Dutch" mutant AbetaE22Q peptide formed fibrils more readily than wild type Abeta and it also attained a heparin-binding state more readily, but, once formed, mutant and wild type fibrils bound heparin with similar affinities. The heparin-binding ability of aggregated AbetaE22Q was reversible with incubation in a solvent that promotes alpha-helical conformation, further suggesting that conformation of the peptide is important. Studies with another human amyloidogenic protein, amylin, suggested that its heparin-binding properties were also dependent on aggregation state. These results demonstrate the dependence of the Abeta-heparin interaction on the conformation and aggregation state of Abeta rather than primary sequence alone, and suggest methods of interfering with this association.

Amino Acid Sequence↗
PubMed1998

The anti-prion activity of Congo red. Putative mechanism.

PrPSc, an abnormal conformational isoform of the normal prion protein, PrPC, is the only known component of the prion, a proteinacious agent that causes fatal neurodegenerative disorders in humans and other animals. The hallmark properties of PrPSc are its insolubility in nondenaturing detergents and its resistance to digestion by proteases. Anions such as Congo red (CR) have been shown to reduce the accumulation of PrPSc in a neuroblastoma cell line permanently infected with prions as well as to delay disease onset in rodents when administrated prophylactically. The mechanism by which such anti-prion agents operate is unknown. We show here that in vitro incubation with CR renders native PrPSc resistant to denaturation by boiling SDS. This resulted from PrPSc conformation, since neither the properties of PrPC nor those of predenatured PrPSc were changed by the addition of CR. CR-PrPSc could only be denatured by the addition of acidic 3 M guanidine thiocyanate. Since in vitro conversion experiments have suggested that partial denaturation may be required for PrPSc to serve as template in the PrPC --> PrPSc conversion, we propose that CR inhibits prion propagation by overstabilizing the conformation of PrPSc molecules.

Animals↗
PubMed2003

Congo red populates partially unfolded states of an amyloidogenic protein to enhance aggregation and amyloid fibril formation.

Congo red (CR) has been reported to inhibit or enhance amyloid fibril formation by several proteins. To gain insight into the mechanism(s) for these apparently paradoxical effects, we studied as a model amyloidogenic protein, a dimeric immunoglobulin light chain variable domain. With a range of molar ratios of CR, i.e. r = [CR]/[protein dimer], we investigated the aggregation kinetics, conformation, hydrogen-deuterium exchange, and thermal stability of the protein. In addition, we used isothermal titration calorimetry to characterize the thermodynamics of CR binding to the protein. During incubation at 37 degrees C or during thermal scanning, with CR at r = 0.3, 1.3, and 4.8, protein aggregation was greatly accelerated compared with that measured in the absence of the dye. In contrast, with CR at r = 8.8, protein unfolding was favored over aggregation. The aggregates formed with CR at r = 0 or 0.3 were typical amyloid fibrils, but mixtures of amyloid fibrils and amorphous aggregates were formed at r = 1.3 and 4.8. CR decreased the apparent thermal unfolding temperature of the protein. Furthermore, CR perturbed the tertiary structure of the protein without significantly altering its secondary structure. Consistent with this result, CR also increased the rate of hydrogen-deuterium exchange by the protein. Isothermal titration calorimetry showed that CR binding to the protein was enthalpically driven, indicating that binding was mainly the result of electrostatic interactions. Overall, these results demonstrate that at low concentrations, CR binding to the protein favors a structurally perturbed, aggregation-competent species, resulting in acceleration of fibril formation. At high CR concentration, protein unfolding is favored over aggregation, and fibril formation is inhibited. Because low concentrations of CR can promote amyloid fibril formation, the therapeutic utility of this compound or its analogs to inhibit amyloidoses is questionable.

Amyloid↗
PubMed2003

Human milk fatty acids and growth of infants in Brazzaville (The Congo) and Ouagadougou (Burkina Faso).

OBJECTIVE: To estimate the role of human milk n-6 and n-3 polyunsaturated fatty acids (PUFA) in term infant growth in two African urban populations. DESIGN: Observational study. Weight gains at 5 months of age and dietary habits were compared between Congolese infants (n=102) and Burkinabè infants (n=101). Socio-economic status and anthropometry of the mothers were also recorded. SETTING: One suburban district in Brazzaville (capital of The Congo) and one in Ouagadougou (capital of Burkina Faso). SUBJECTS: Two random samples of nursing mothers and their 5-month-old infants. RESULTS: All infants were born at term and there was no difference in birth weights. At 5 months of age, infants in Ouagadougou were thinner but not shorter than their counterparts in Brazzaville (average weight gain (standard deviation): 614 (168) g month-1 vs. 720 (176) g month-1; P= 0.0001). Drastic differences were found in infant diets with regard to extra fluid intake and n-6 and n-3 PUFA concentrations in breast milk. In Ouagadougou, all infants were given fluids other than milk from birth. Breast milk had highly unbalanced 18:2n-6/18:3n-3 and n-6/n-3 long-chain PUFA ratios (53:1 and 5:1, respectively). In Brazzaville, half of the infants received fluids other than milk, and breast milk showed balanced 18:2n-6/18:3n-3 and n-6/n-3 long-chain PUFA ratios (12:1 and 1:1, respectively). A non-linear relationship between 18:2n-6/18:3n-3 ratio and growth was established in Brazzaville (P= 0.0027). The 18:2n-6/18:3n-3 ratio adjusted with covariates had an even more significant effect on weight gain (P= 0.0011). Applying the same model in Ouagadougou did not show such a relation. CONCLUSION: : Data strongly suggest that a balanced ratio of 18:2n-6/18:3n-3 (between 5:1 and 15:1) in breast milk leads to higher weight gain of infants during the first 5 months of life.

Adult↗
PubMed1989

The host preferences of Chrysops silacea and C. dimidiata (Diptera: Tabanidae) in an endemic area of Loa loa in the Congo.

The analysis of 404 blood meals from Chrysops silacea and C. dimidiata which had been collected in the forests of the Chaillu mountains (People's Republic of the Congo) has demonstrated for the first time that both species also feed on non-human hosts. For both species the feeding patterns are fairly similar. However, man remains the main host in 89-90% of the cases. C. silacea and C. dimidiata took 6 and 4% respectively of their blood meals from hippopotamuses, 2 and 0% from rodents, 2 and 4% from wild ruminants, and 0.8 and 0.7% from monitor lizards. Whenever a differentiation has been made between the different members of the primates, only meals from humans but not from chimpanzees or baboons have been detected. The results may provide an explanation for the distinct barrier between the simian and human loiasis infections. They also give evidence for the ability of both vectors to travel over prolonged distances.

Animals↗
PubMed1990

Epidemiology of Mansonella perstans filariasis in the forest region of south Congo.

A study of Mansonella perstans filariasis conducted in the Chaillu mountains, Southern Congo, showed that 108 of 134 Pygmies (80.6%) and 79 of 302 Bantus (26.2%) presented with microfilaraemia. The mean microfilarial densities were also significantly higher in the Pygmies (1213 ml-1 of blood) than in the Bantus (136 ml-1). Ninety eight per cent of the Culicoides taken which had bitten man in the daytime were C. grahamii, and 0.8% of these were infected with filarial larvae. Two other species of Culicoides (C. kumbaensis and C. rutshuruensis) might also play a role in the transmission of M. perstans.

Adolescent↗
PubMed1992

Current practices for the prevention and treatment of malaria in children and in pregnant women in the Brazzaville Region (Congo).

Current practices for the prevention and treatment of malaria in children and in pregnant women in the Brazzaville Region (Congo) were studied in 1989 and 1990. Information was obtained by interviewing a total of 1152 subjects. Overall, chemoprophylaxis was used less than was the systematic treatment of fever. Fever was treated before seeking medical advice in over 50% of the cases. Two-thirds of those interviewed reported that they slept under mosquito nets. Families with lower socio-economic standards were less likely to use chemoprophylaxis, to have antimalarials in the home, and to own mosquito nets; and they were more likely to prefer injections and to purchase drugs in the local markets.

Antimalarials↗