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In scrapie-infected cells, Congo red inhibits both the replication of the infectious agent and accumulation of the protease-resistant form of PrP (PrP-res). In this report, we show that Congo red prolongs the incubation periods of hamsters experimentally infected with two different strains of scrapie.
The mode and the site of action of the major antiscrapie drugs have been studied by investigating their effects on the abnormal protease-resistant isoform of PrP (PrPres) and on its accumulation in mouse spleen. Day-by-day PrPres accumulation in the spleen and in other peripheral organs was first monitored to describe the early steps of scrapie pathogenesis. Three phases were identified: the detection of scrapie inoculum on the day of scrapie infection, a clearance phase, and then the peripheral accumulation of PrPres. In a second step, the effects of the polyene antibiotic MS-8209, the polyanion dextran sulfate 500 (DS500), and Congo red were assessed on these phases, after the drugs were coincubated with scrapie inoculum. Highly different mechanisms and sites of action were apparent. MS-8209 had a weak effect on the accumulation of PrPres in spleen, suggesting another site of intervention for this drug. DS500 delayed the beginning of the clearance phase but then blocked PrPres synthesis for a long period of time, probably because of its immunological effects on the spleen. Surprisingly, Congo red suppressed the clearance phase of scrapie inoculum and then increased transiently accumulation of PrPres in spleen. We showed in vitro that this effect was related to a direct enhancement of the protease resistance of PrPres by the drug.
G6PD genotypes were determined in Brazzaville (Congo) on 188 HbSS patients (109 females, 79 males) and 210 controls (115 females and 95 males) with HbAA. DNA samples were analyzed by the polymerase chain reaction (PCR). The frequencies of G6PD B, A+ and A- alleles were 56.9, 20.8 and, 22.2% in the patients versus 56.3, 21.2 and, 22.5% in the controls, respectively. The prevalence of G6PD genotypes in HbSS did not differ (p > 0.05) from that found in the controls. Prevalence of G6PD deficiency did not change when patients were stratified by age, suggesting that there is no advantage of the association of G6PD deficiency with HbSS. Red blood cell count, mean corpuscular volume and mean corpuscular hemoglobin were not modified by the G6PD genotypes, while Hb level was lower in HbSS with G6PD A-. Our study suggests that in Congo, G6PD deficiency does not offer any biological advantage to sicklers.
X-34, a lipophilic, highly fluorescent derivative of Congo red, was examined as a histochemical stain for pathological changes in Alzheimer's disease (AD). X-34 intensely stained neuritic and diffuse plaques, neurofibrillary tangles (NFTs), neuropil threads, and cerebrovascular amyloid. Comparison to standard methods of demonstrating AD pathology showed that X-34 correlated well with Bielschowsky and thioflavin-S staining. X-34 staining of NFTs correlated closely with anti-TAU antibody staining. A 1:1 correspondence of X-34 and anti-A beta antibody staining of plaques and cerebrovascular amyloid was observed. Both X-34 and thioflavin-S staining were eliminated by formic acid pretreatment, suggesting that beta-sheet secondary protein structure is a necessary determinant of staining. X-34 may be a general amyloid stain, like Congo red, because it also stains systemic amyloid deposits due to lambda-light chain monoclonal gammopathy. In conclusion, X-34 is a highly fluorescent marker for beta-sheet structures and intensely labels amyloid plaques, NFTs, neuropil threads, and vascular amyloid in AD brains. It can be used with both paraffin-embedded and frozen tissues as well as in combination with immunohistochemistry for double labeling. The intensity of staining and the simplicity and reproducibility of the technique suggest that it may be a useful addition to the standard techniques for evaluation of AD neuropathology. (J Histochem Cytochem 48:1223-1232, 2000)
Sirius red and Congo red were compared for specificity and sensitivity of amyloid staining in animal and human material. Previously described advantages of Sirius red as an amyloid dye were confirmed, as well as its disadvantage of lack of ultraviolet fluorescence. Two further disadvantages of Sirius red were discovered, both relating to animal material: (a) its unexpectedly weak staining of early experimentally induced amyloid deposits and (b) frequent uncontrollable nonspecific staining of fibrous tissues. It is therefore concluded that, overall, Congo red used by the improved alkaline technique of Puchtler, Sweat and Levine (1962) remains the best single method for demonstration of amyloid in both human and animal tissues.
BACKGROUND: Presented here are the results of a comparative trial on the efficacy of three artemisinin-based combinations conducted from May to October 2004, in Pool Province, Republic of Congo. METHODS: The main outcome was the proportion of cases of true treatment success at day 28. Recrudescences were distinguished from re-infections by PCR analysis. A total of 298 children of 6-59 months were randomized to receive either artesunate + SP (AS+SP), artesunate + amodiaquine (AS+AQ) or artemether + lumefantrine (AL), of which 15 (5%) were lost to follow-up. RESULTS: After 28 days, there were 21/85 (25%) recurrent parasitaemias in the AS+SP group, 31/97 (32%) in the AS+AQ group and 13/100 (13%) in the AL group. The 28-day PCR-corrected cure rate was 90.1% [95% CI 80.7-95.9] for AS+SP, 98.5% [95% CI 92.0-100] for AS+AQ and 100% [95.8-100] for AL, thereby revealing a weaker response to AS+SP than to AL (p = 0.003) and to AS+AQ (p = 0.06). A potential bias was the fact that children treated with AL were slightly older and in better clinical condition, but logistic regression did not identify these as relevant factors. There was no significant difference between groups in fever and parasite clearance time, improvement of anaemia and gametocyte carriage at day 28. No serious adverse events were reported. CONCLUSION: Considering the higher efficacy of AL as compared to AS+SP and the relatively high proportion of cases with re-infections in the AS+AQ group, we conclude that AL is clinically more effective than AS+SP and AS+AQ in this area of the Republic of Congo. Implementation of the recently chosen new national first-line AS+AQ should be monitored closely.
Crimean-Congo haemorrhagic fever (CCHF) is an often fatal viral infection described in about 30 countries around the world. The authors report a fatal case of Crimean-Congo hemorrhagic fever (CCHF) observed in a patient from Kosova. The diagnosis of CCHF was confirmed by reverse transcription-PCR. Late diagnosis decreased the efficacy of treatment and patient died due to severe complications of infection.
We have reported the antiulcer activities of a new compound that we named NIK-228 (3-hydroxy-methyl-2-methylimidazo [2, 1-b] benzothiazole). In the present report, we studied the antisecretory effects of NIK-228 on basal and stimulated gastric acid secretion using the Congo red sprayed method. Male Wistar rats (200 to 250 g) were used after 24 hr of fasting (without water). NIK-228, atropine and cimetidine were administered orally or intravenously 1 hr before operation for Congo red spraying. NIK-228 (100 mg/kg, p.o.), atropine (5 mg/kg p.o.) and cimetidine (100 mg/kg, p.o.) all inhibited basal gastric acid secretion. Oral administration of NIK-228 and atropine inhibited gastrin, 2-deoxy-D-glucose (2-DG) and bethanechol-induced acid secretion, but didn't inhibit histamine-induced acid secretion. Cimetidine inhibited all of histamine, gastrin, 2-DG and bethanechol-induced acid secretion. In vagotomized rats, oral and intravenous administration of atropine both inhibited bethanechol-induced acid secretion, but NIK-228 was not inhibited. These results suggested that antisecretory effects of NIK-228 were caused by the central vagal systems.
The prevalence of Toxoplasma gondii in free-ranging chickens (Gallus domesticus) is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. In the present study, prevalence of T. gondii in chickens from Democratic Republic of Congo, Mali, Burkina Faso, and Kenya is reported. The prevalence of T. gondii antibodies in sera of 50 free-range chickens from Congo was 50% based on the modified agglutination test (MAT); antibody titers were 1:5 in 7, 1:10 in 7, 1:20 in 6, 1:40 in 1, and 1:160 or more in 4 chickens. Hearts, pectoral muscles, and brains of 11 chickens with titers of 1:20 or more were bioassayed individually in mice; T. gondii was isolated from 9, from the hearts of 9, brains of 3, and muscles of 3 chickens. Tissues of each of the 14 chickens with titers of 1:5 or 1:10 were pooled and bioassayed in mice; T. gondii was isolated from 1 chicken with a titer of 1:10. Tissues from the remaining 25 seronegative chickens were pooled and fed to 1 T. gondii-free cat. Feces of the cat were examined for oocysts, but none was seen. The results indicate that T. gondii localizes in the hearts more often than in other tissues of naturally infected chickens. Genotyping of these 10 isolates using the SAG2 locus indicated that 8 were isolates were type III, 1 was type II, and 1 was type I. Two isolates (1 type I and 1 type III) were virulent for mice. Toxoplasma gondii was isolated by mouse bioassay from a pool of brains and hearts of 5 of 48 chickens from Mali and 1 of 40 chickens from Burkina Faso; all 6 isolates were avirulent for mice. Genetically, 4 isolates were type III and 2 were type II. Sera were not available from chickens from Mali and Burkina Faso. Toxoplasma gondii antibodies (MAT 100 or more) were found in 4 of 30 chickens from Kenya, and T. gondii was isolated from the brain of 1 of 4 seropositive chickens; this strain was avirulent for mice and was type II. This is the first report on isolation and genotyping of T. gondii from any source from these 4 countries in Africa.
OBJECTIVE: In 2002-03, the Republic of the Congo increased the threshold separating stage 1 and 2 cases of human African trypanosomiasis (HAT) from a cerebrospinal fluid (CSF) white cell count of 5 cells/mm(3) to 10 cells/mm(3). We aimed to assess whether the increased threshold of 10 cells/mm(3) is a safe indicator of stage 2 disease. METHODS: We assessed patients treated for stage 1 HAT caused by Trypanosoma brucei gambiense in the Republic of the Congo between April 2001 and April 2005. Patients with 0-10 cells/mm(3) in CSF were classed as stage 1 and treated with pentamidine. Patients with CSF of > 10 cells/mm(3) were classed as stage 2 and treated with either melarsoprol or eflornithine. We did a retrospective analysis of all patients treated after the September 2002 increase in threshold for classification of HAT disease stage 2, and who were eligible for at least 1 year of follow-up. Primary outcome was survival without death or relapse within 1 year of discharge. Risk factors for treatment failure, in particular CSF white cell count on diagnosis, were assessed. FINDINGS: Between September 2002 to April 2004, 692 patients eligible for our analysis were treated with pentamidine. All were discharged alive. Relapse rate was 5% (n = 33). The only identified risk factor for relapse was a CSF white cell count of 6-10 cells/mm(3) rather than 0-5 cells/mm(3) (adjusted hazard ratio 3.27 (95% confidence interval, 1.52-7.01); P = 0.002). CONCLUSION: A threshold of 5 white cells/mm(3) in CSF is safer than 10 cells/mm(3) to determine stage 2 HAT and reduce risk of relapse.
OBJECTIVE: To compare the effectiveness of melarsoprol and eflornithine in treating late-stage Gambian trypanosomiasis in the Republic of the Congo. METHODS: We analysed the outcomes of death during treatment and relapse within 1 year of discharge for 288 patients treated with eflornithine, 311 patients treated with the standard melarsoprol regimen and 62 patients treated with a short-course (10-day) melarsoprol regimen between April 2001 and April 2005. FINDINGS: A total of 1.7% (5/288) of patients treated with eflornithine died compared with 4.8% (15/311) of those treated with standard melarsoprol and 6.5% (4/62) of those treated with short-course melarsoprol. Patients treated with eflornithine tended to be younger and were more likely to have trypanosomes or higher white blood cell counts in their cerebrospinal fluid. The cumulated incidence of relapse among patients who attended at least one follow-up visit 1 year after discharge was 8.1% (11/136) for those treated with eflornithine, 14% (36/258) for those treated with standard melarsoprol and 15.5% (9/58) for those treated with shortcourse melarsoprol. In a multivariate analysis, when compared with eflornithine, standard melarsoprol was found to be a risk factor for both death (odds ratio (OR) = 2.87; 95% confidence interval (CI) = 1.03-8.00) and relapse (hazard ratio (HR) = 2.47; 95% CI = 1.22-5.03); when compared with eflornithine, short-course melarsoprol was also found to be a risk factor for death (OR = 3.90; 95% CI = 1.02-14.98) and relapse (HR = 6.65; 95% CI = 2.61-16.94). CONCLUSION: The effectiveness of melarsoprol treatment appears to have diminished. Eflornithine seems to be a better first-line therapy for treating late-stage Gambian trypanosomiasis in the Republic of the Congo.
The use of Congo red as an elective stain for eosinophilic granulocytes and their precursors in tissue sections and autoradiographs is demonstrated and discussed. The 0.5% alcoholic Congo red solution of Highman, normally used for the detection of amyloid, may also be used with only minor changes. This simple method may aid in the diagnosis of special hematological problems and facilitates the recognition of eosinophil granulocytes as well as proliferating and nonproliferating myelocytes in autoradiographs from paraffin sections.
The binding mechanism of Congo red (CR) to Alzheimer's disease (AD) amyloid fibrils (A beta) in terms of binding affinity and number of sites was quantitated from absorption spectroscopy (at 200-700 nm) by measuring the concentration of CR bound (CR-B) to AD A beta assemblies as a function of CR concentration and pH in 80% ethanol. The rationale for the use of this high concentration of ethanol derives from its use in histological screens for amyloid in tissue sections. Moreover, free CR can be separated from bound CR by filtration in ethanolic but not aqueous medium. The A beta analogs studied here included: (1) peptides having different lengths: A beta1-40, A beta11-28, A beta13-28, A beta19-28, A beta11-25; (2) wildtype, control sequences of A beta1-40 and sequences having different natural amino acid substitutions: primate Pr1-40, rodent Ro1-40, hereditary cerebral haemorrhage with amyloidosis, Dutch type (HCHWA-D) Du1-40, primate reverse sequence Pr40-1; and (3) A beta11-25 sequences having different substitutions: H13D, H14D, and D23K. Negative-staining showed that A beta1-40 fibrils in buffer were indistinguishable from those in buffered ethanolic medium. For all amyloid analogs except A beta19-28, which has no histidine residues and showed no CR binding over the entire pH range 4.0-9.5, CR-B decreased as a function of increasing pH. The decrease was steepest at about pH 5 and became zero above pH 7. For analogs having the same number of histidines, CR-B fell on the same binding curve, indicating that histidine residues are the likely binding sites for CR in this medium. The pH titration of the binding was parameterized by the stoichiometry of dye to the sites, the number of histidines per molecule, the binding dissociation constant Kd, and the apparent proton dissociation constant pK of the histidine; and the calculated pH-titration curves were found to fit the observed ones. For the peptides having 1-3 histidines the average pK was 5.0-5.5, which was similar to the expected pK of histidine in low dielectric medium (80% ethanol), and the Kd's were 2.8-5.9 microM. That histidine residues underlie CR binding in A beta amyloid is consistent with previous findings that A beta peptides sediment as fibrillar assemblies at pH-3-7 and bind Congo red over the same pH range in aqueous medium. Further, the conformation near the binding motif His13-His14-Gln15-Lys16 in A beta assemblies is not greatly altered in 80% ethanol.
HIV and AIDS prevention is part of the biology class curriculum in junior high and high school in both France and the Congo. The teachers must not only present the scientific knowledge but also try to incite and convince the students to adopt certain preventive behaviours in terms of their own personal conduct. This places the teachers in the domain of having a health promotion and education role. How do teachers perceive this new role? What objectives and outcome measures have they set, and what kind of educational method do they intend to use to achieve them? Based on interviews conducted in the year 2000 of 25 teachers (12 in France and 13 in Congo-Brazzaville), a profile has been defined for each teacher based on an analysis of his/her responses with regard to their role in terms of health education and more specifically in relation to AIDS prevention. A number of questions and concems emerged from this exercise, some of which were shared in common and others were clearly country-specific.
The viability of Schistosoma mansoni miracidia, either hatched or unhatched, has been assessed by a staining technique using Congo red, a pH-sensitive dye (pH 3-5), under the light microscope. Hatched, free-swimming miracidia and live miracidia inside egg shells were stained light blue whereas dying miracidia altered the dye color from blue to orange and eventually to red. Immature eggs containing undeveloped miracidia were not stained by Congo red. This staining technique is simple, rapid and can be used as a method to assess both the viability of S. mansoni miracidia and the hatching process.
The epidemiology of onchocerciasis in much of the Democratic Republic of the Congo (formerly Zaire) is not well established. We report the results of an onchocerciasis rapid assessment survey carried out in 18 villages of the Sankuru River Valley in the central part of this country in preparation for mass distribution of ivermectin. Thirty men from each village were randomly selected and examined for subcutaneous nodules. The prevalence of nodules among these men in each village ranged from 82.5% to 100% with a mean prevalence of 95.0%. This study also assessed the validity of using verbal assessment instead of physical examination to determine prevalence of nodules. This verbal method had a sensitivity of 93.5% and a specificity of 83.3%. High sensitivity and specificity for this method suggest that it might be a cost-effective approach to determine the prevalence of onchocerciasis over large areas without using physical examinations requiring medical personal. This approach could be particularly useful where the coverage of health services is poor. The use of the Global Positioning System made it possible to send coordinates and survey data electronically to World Health Organization personnel in Geneva for computer generation of prevalence maps. The use of river boats to conduct surveys and support ivermectin distribution in the Congo is discussed.
In February 1998, an outbreak of acute febrile illness was reported from the Kapalata military camp in Kisangani, the Democratic Republic of Congo. The illness was characterized by an acute onset of fever associated with severe headache, arthralgia, backache, neurologic signs, abdominal pain, and coughing. In 1 individual, hemorrhagic manifestations were observed. The neurologic signs included an altered level of consciousness, convulsions, and coma. Malaria was initially suspected, but the patients showed negative blood films and failed to respond to antimicrobial drugs. A total of 35 sera collected from the military patients in the acute phase were tested for the presence of IgM against vector-borne agents. Serum IgM antibodies against West Nile fever virus were found in 23 patients (66%), against Chikungunya virus in 12 patients (34%), against dengue virus in 1 patient (3%), and against Rickettsia typhi in 1 patient (3%). All sera were negative for IgM antibody against Rift Valley fever virus, Crimean Congo hemorrhagic fever virus, and Sindbis virus. These data suggest that infections with West Nile fever virus have been the main cause of the outbreak.
The Democratic Republic of Congo (DRC, former Zaire) in central Africa remains the foremost country for leprosy in Africa, with a total of 4877 registered cases, of which 4573 are new cases since 1997. These numbers are well above the regional average. About 94% of these patients are under multidrug therapy (MDT) coverage in the Congo, which ranks 8th in coverage rate among the surrounding nine nations. Available data on anatomo-clinical profile and bacillarity are provided, with reservations on the use of these data drwn due to relatively small sample sizes. The seroprofile of the disease was reviewed with regard to the association of other immunity impairing infections like HBV infection and the recently highly incident retroviral epidemics (HIV-1, HTLV-1, and HTLV-2). The leading role of non-governmental organizations is cited for improving leprosy patient conditions and also for future prospects, where the necessity of coordinated strategies with the government is emphasized. Recommendations for new trends and steps relevant to improving existing and future leprosy control strategies are put into perspective.