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No clinical or biological difference between Chikungunya and Dengue Fever during the 2010 Gabonese outbreak
Dieudonne Nkoghe,Roland Fabrice Kassa Kassa,Ulrich Bisvigou,Mélanie Caron
Infectious Disease Reports , 2012, DOI: 10.4081/idr.2012.e5
Abstract: Chikungunya (CHIKV) and Dengue (DENV) viruses, both arboviruses, have caused multiple outbreaks worldwide. Their clinical features are poorly described in Africa and there is no comparative study, although Chikungunya is considered as a dengue-like disease. We conducted a comparative study of clinical and biological data from CHIKV and DENV positive patients during the 2010 Gabonese outbreak. Patients consulting with general symptoms and having laboratory confirmation for CHIKV or DENV were included. Clinical and biological data were recorded. Statistical analyses were performed using Epi Info. A P value < 0.05 was considered significant. In all, 270 CHIKV+, 53 DENV+ and 20 co-infected patients were included in the study. Headaches, hemorrhage, leukopenia and lymphopenia were significantly (P respectively 0.01, 0.001, 0.02 and 0.001) more frequent in DENV+ patients than in CHIKV+. There was no additive effect of the two viruses. These clinical and hematological disorders are non specific and cannot assist for the differential diagnosis. These diseases are clinically indistinguishable, and need for laboratory confirmation.
First Evidence of Simultaneous Circulation of Three Different Dengue Virus Serotypes in Africa
Melanie Caron, Gilda Grard, Christophe Paupy, Illich Mamfred Mombo, Branly Bikie Bi Nso, Fabrice Roland Kassa Kassa, Dieudonne Nkoghe, Eric Maurice Leroy
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0078030
Abstract: Gabon, in Central Africa, was affected for the first time in 2007 and then in 2010 by simultaneous outbreaks of chikungunya and Dengue serotype 2 (DENV-2) viruses. Through the national surveillance of dengue-like syndromes between 2007 and 2010, we observed continuous circulation of DENV-2 in a southward movement. This rapid spread of DENV-2 was associated with the emergence of DENV-1 in 2007 and DENV-3 in 2010. Interestingly, we detected six DENV-2 infected patients with hemorrhagic signs during the second outbreak in 2010. Although these cases do not meet all standard WHO criteria for severe Dengue with hemorrhage (formerly DHF), this is the first report of several dengue fever cases associated with hemorrhagic signs during a simultaneous circulation of different DENV serotypes in Africa. Together, these findings suggest that DENV is becoming more widely established on this continent and that DHF will likely become a serious public-health problem in the near future.
Boundedness and Compactness of Toeplitz operators with L^1 symbols on the Bergman space
Dieudonne Agbor
Mathematics , 2007,
Abstract: We characterise the boundedness of a Toeplitz operator on the Bergman space with an L^1 symbol.We also prove that the compactness of a Toeplitz operator on the Bergman space with an L^1 symbol is completely determined by the boundary behaviour of itss Berezin transform. This result extends known results in the cases when the symbol is either a positive L^1 function, an L^\infty function or a general BMO^1 function.
Boundedness and Compactness of products of Toeplitz operators on the Bergman Space
Dieudonne Agbor
Mathematics , 2007,
Abstract: In a celebrated conjecture D.Sarason stated a necessary and sufficient condition on the symbols f, g in the Bergman space, L^2_a(\Delta) of the unit disk, \Delta, for the products T_{f}T_{\bar g} of associated Toeplitz operators to be bounded (respectively compact) on L^2_a(\Delta) . K. Stroethoff and D. Zheng proved that these conditions are necessary. We prove the sufficiency of these conditions, thus solvind Sarason's conjecture.
Assessing the Performance of Large-scale Logging Companies in Countries of the Congo Basin
Dieudonne Alemagi,Daniel Nukpezah
Environment and Natural Resources Research (ENRR) , 2012, DOI: 10.5539/enrr.v2n2p38
Abstract: This article critically reviews the socio-economic and environmental performance of large-scale logging companies operating in countries endowed with the dense tropical rainforest of the Congo Basin in Central Africa and offers possible solutions to problems identified. After independence, these countries formulated a series of strategies to attract foreign investment in the large-scale logging industry. Recently, while a plethora of policies and regulations have been designed to advance sustainable forest management in these countries, the sustainability of this industry has been brought into question in light of the impoverish state of local forest-dependent communities. Thus, the purpose of this paper is to examine the regulatory framework of this industry in the developing world, as well as assess their performance with a particular focus on six countries where the forests of the Congo Basin are concentrated in Central Africa.
Textures and Rare Earth Elements Composition of Banded Iron Formations (BIF) at Njweng Prospect, Mbalam Iron Ore District, Southern Cameroon  [PDF]
Dieudonne Charles Isidore Ilouga, Cheo Emmanuel Suh, Ghogomu Richard Tanwi
International Journal of Geosciences (IJG) , 2013, DOI: 10.4236/ijg.2013.41014

The REE signature of banded iron formations (BIF) and martite-goethite mineralization of the Njweng ridge (South Cameroon) are used here to decipher the nature of the ocean during the period of BIF precipitation. The textures of typical BIF categories are also presented as the only sedimentary feature. Two types of BIF facies are present at Njweng: the oxide and silicate facies. These facies show two stages of phase transformations. The first is the transformation of the original magnetite mineral into martite by oxidation resulting in trellis texture; the second is a simultaneous transformation by hydration into goethite and dehydration into martite. The samples typically show LREE depleted patterns relative to HREE, a characteristic similar to that of modern seawater. Also the strong positive Eu anomalies from the samples indicate the involvement of hydrothermal plumes of volcanic origin such as at mid ocean ridges (MOR). Yttrium (Y) has a strong positive anomaly pointing to the transportation of REEs as aqueous complexes within these ancient seas. The BIF samples have no positive Ce anomalies, suggesting that the oceans at that time were more reducing with no Ce fractionation than in present day oceans. The martite-goethite mineralization rather shows a positive Ce anomaly that derived from the enrichment in REE during the weathering of REE-bearing minerals. These results are integrated into existing literature on REE in BIFs worldwide and provide new insights into these heretofore unstudied BIFs of the northern edge of the Congo Craton.

From Land Cover to Landscape Structure: Change and Fragmentation Analysis in Korup National Park, Cameroon
Ndoh Mbue Innocent,Bitondo Dieudonne
Journal of Geography and Geology , 2012, DOI: 10.5539/jgg.v4n1p103
Abstract: Can the designation of protected area status in a human inhabited ecosystem limit anthropogenic activities within the boundaries of the protected area? To attempt an answer to this question, we used the Central zone of Korup National Park, Cameroon as an example. Comparing two satellite imageries (1986 and 2000), it was possible to assess land cover transformations, and with the FRAGSTATS software it was possible to quantify the changes of landscape characteristics in the area fourteen years after the creation of the park in 1986. The results revealed an increase in exposed surfaces (15.61%), which came at the expense of forest-land-cover (-12.69%) and water bodies (-2.92%). Meanwhile, landscape metrics demonstrated significant changes including, an increase in the number and size of patch, diversity and fragmentation. Overall, structural metrics for landscape indicated that anthropogenic activities still continue within the boundaries of the park. The results con?rm the effectiveness of the combined method of remote sensing and metrics.
Identification of Continuous Human B-Cell Epitopes in the VP35, VP40, Nucleoprotein and Glycoprotein of Ebola Virus
Pierre Becquart, Tanel Mahlak?iv, Dieudonné Nkoghe, Eric M. Leroy
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096360
Abstract: Ebola virus (EBOV) is a highly virulent human pathogen. Recovery of infected patients is associated with efficient EBOV-specific immunoglobulin G (IgG) responses, whereas fatal outcome is associated with defective humoral immunity. As B-cell epitopes on EBOV are poorly defined, we sought to identify specific epitopes in four EBOV proteins (Glycoprotein (GP), Nucleoprotein (NP), and matrix Viral Protein (VP)40 and VP35). For the first time, we tested EBOV IgG+ sera from asymptomatic individuals and symptomatic Gabonese survivors, collected during the early humoral response (seven days after the end of symptoms) and the late memory phase (7–12 years post-infection). We also tested sera from EBOV-seropositive patients who had never had clinical signs of hemorrhagic fever or who lived in non-epidemic areas (asymptomatic subjects). We found that serum from asymptomatic individuals was more strongly reactive to VP40 peptides than to GP, NP or VP35. Interestingly, anti-EBOV IgG from asymptomatic patients targeted three immunodominant regions of VP40 reported to play a crucial role in virus assembly and budding. In contrast, serum from most survivors of the three outbreaks, collected a few days after the end of symptoms, reacted mainly with GP peptides. However, in asymptomatic subjects the longest immunodominant domains were identified in GP, and analysis of the GP crystal structure revealed that these domains covered a larger surface area of the chalice bowl formed by three GP1 subunits. The B-cell epitopes we identified in the EBOV VP35, VP40, NP and GP proteins may represent important tools for understanding the humoral response to this virus and for developing new antibody-based therapeutics or detection methods.
The use of a Cissus quadrangularis formulation in the management of weight loss and metabolic syndrome
Julius Oben, Dieudonne Kuate, Gabriel Agbor, Claudia Momo, Xavio Talla
Lipids in Health and Disease , 2006, DOI: 10.1186/1476-511x-5-24
Abstract: The study was a randomized, double-blind, placebo-controlled design involving 123 overweight and obese persons (47.2% male; 52.8% female; ages 19–50). The 92 obese (BMI >30) participants were randomized into three groups; placebo, formulation/no diet, and formulation/diet (2100–2200 calories/day). The 31 overweight participants (BMI = 25–29) formed a fourth (no diet) treatment group. All participants received two daily doses of the formulation or placebo and remained on a normal or calorie-controlled diet for 8 weeks.At the end of the trial period, statistically significant net reductions in weight and central obesity, as well as in fasting blood glucose, total cholesterol, LDL-cholesterol, triglycerides, and C-reactive protein were observed in participants who received the formulation, regardless of diet.Cissus quadrangularis formulation appears to be useful in the management of weight loss and metabolic syndrome.Although still defined in diverse terms, metabolic syndrome is a common disorder arising as a result of the increased prevalence of obesity throughout the world [1]. Metabolic syndrome, also known as insulin resistance syndrome and Syndrome X, has 3 main potential etiologic categories: obesity and disorders of adipose tissue; insulin resistance; and a constellation of independent factors (e.g., molecules of hepatic, vascular, and immunologic origin) that mediate specific components of the metabolic syndrome [2].In the United States, over 60% of the adult population is now overweight or obese [3] and 47 million people have metabolic syndrome, which will soon overtake cigarette smoking as the number one risk factor for heart disease [4,5]. Globally, the disorder has become a major public health challenge. (In Cameroon, approximately 25% of the population is now considered obese.)Obesity has been shown to contribute to high serum cholesterol, low HDL cholesterol and hyperglycemia, all of which increase the chances of cardiovascular disease (CVD) [6-8]. Correl
In Vitro Antibacterial Activity of Crinum Purpurascens Herb. Leaf Extract Against the Salmonella Species Causing Typhoid Fever and Its Toxicological Evaluation
Donatien Gatsing,Veronique Tchakoute,Dieudonne Ngamga,Jules-Roger Kuiate
Iranian Journal of Medical Sciences , 2009,
Abstract: Background: Crinum purpurascens is a herbaceous plant belongingto the Amaryllidaceae family. We aimed to evaluatethe antisalmonellal properties of the leaf extracts and fractionsof C. purpurascens, and the toxicity of the most active extract.Methods: Three extracts and three fractions were prepared fromthe leaves of Crinum purpurascens Herb. (Amaryllidaceae) andtested for their antisalmonellal activities and toxicity profile. Theantibacterial activity was determined using agar diffusion, agardilution, and broth dilution techniques. Phytochemical screeningof the various extracts and fractions was performed. The toxicityprofile of the CH2Cl2/MeOH (1:1) extract was studied.Results: All the extracts and fractions, except hexane fraction,showed antimicrobial activity against Salmonella typhi, Salmonellaparatyphi A and Salmonella paratyphi B. TheCH2Cl2/MeOH (1:1) extract showed the highest activity. Theminimum inhibitory concentration values were 2.50 mg/mlagainst S. typhi, and 1.88 mg/ml against S. paratyphi A and S.paratyphi B. The minimum bactericidal concentration values were7.50 mg/ml against S. typhi and 3.75 mg/ml against S. paratyphiA and S. paratyphi B. Mice administered high doses of extractexhibited reduced reaction to noise, locomotion, reactivity andreaction to pinch, and losses in body weight. Additionally, the ratsthat received high doses of the extract showed increase in liver,spleen and kidney to body weight ratios, and decrease in total proteinconcentrations of the liver and lung, and in hematocrit value.Conclusion: C. purpurascens leaf extract contains antisalmonellalprinciple(s) and at high doses, may have a depressant or sedativeeffect on the central nervous system and analgesic activity.Also, it may be anorexiant, hepatotoxic, and nephrotoxic.
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