University of Yaounde1

Yaoundé, Cameroon

University of Yaounde1

Yaoundé, Cameroon
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Njamen D.,University of Yaounde1 | Nkeh-Chungag B.N.,Walter Sisulu University | Tsala E.,University of Yaounde I | Fomum Z.T.,University of Yaounde I | Mbanya J.C.,University of Yaounde1
Tropical Journal of Pharmaceutical Research | Year: 2012

Purpose: To evaluate the hypoglycaemic effect of the methanol extract of Bridelia ferruginea leaves (MEBF) on sucrose-induced glucose intolerance in rats. Methods: Male Wistar rats, aged 6 - 7 weeks and weighing 140 - 160 g, were used. The animals were fed standard rat chow supplemented with 35%, 50% or 65% sucrose for 8 weeks while control animals were fed standard rat chow. The hypoglycaemic effect of MEBF and the reference drugs (tolbutamide, and metformin) in the animals were evaluated following a single dose of these drugs and 6-day treatment. Plasma lipid profiles were also determined. Results: Fasting glucose concentrations ranged from 45 to 70 mg/dl, and the increase was significant in the sucrose diet groups from week 1. After 2 weeks on these diets, oral glucose tolerance test showed that sucrose feeding significantly impaired glucose homeostasis 1 and 2 hours after a glucose challenge (76.7 ± 2.0 versus 86.4 ± 8.5 and 66.7 ± 1.4 versus 75.5 ± 3.0, respectively). Fasting blood sugar levels were significantly (p < 0.05) reduced in sucrose-induced, glucose-intolerant rats after a single dose of MEBF. The extract also significantly reduced blood glucose (from 167 ± 23 mg/dL to 126 ± 5 mg/dL), serum total cholesterol (from 161 ± 20 mg/dL to 93 ± 10 mg/dL) and triglyceride levels (281 ± 25 mg/dL to 228 ± 5 mg/dL) in glucose intolerant rats after 6 days of treatment. Conclusion: The methanol leaf extract of Bridelia ferruginea exhibited hypoglycaemic effect in glucoseintolerant rats. © Pharmacotherapy Group.

Florence N.T.,University of Yaounde1 | Huguette S.T.S.,University of Yaounde1 | Hubert D.J.,University of Dschang | Raceline G.K.,University of Yaounde1 | And 3 more authors.
BMC Complementary and Alternative Medicine | Year: 2017

Background: Peperomia pellucida (L.) HBK is consumed as vegetable and used in Cameroonian traditional medicine for the management of diseases and for fracture healing. Therefore the aim of this study was to evaluate the effects of the aqueous whole plant extract of Peperomia pellucida on fracture healing in female Wistar rats. Methods: A drill hole injury was created by inserting a drill bit inthe diaphysis of the femur. The aqueous extract of the whole plant of Peperomia pellucida was administered orally at the doses of 100, 200 and 400 mg/kg to adult female Wistar rats. The vehicle (distilled water) was given to the control. Besides these rats, one group of rats without fracture received the extract (400 mg/kg). After 14 days of treatment, the rats were sacrificed under anesthesia and the effects of the extract were evaluated on body weight, the relative weights of organs (femurs, uteri and ovaries) and on hematology. Bone (calcium, phosphorus, alkaline phosphatase) and serum biochemical parameters (calcium, phosphorus, alkaline phosphatase) were also evaluated. Radiological and histological tests were carried out on the femurs. The mineral content of the plant extract was also investigated. Results: The extract induced an increase in body weight at high dose and in WBCs count at low doses. Aqueous extract from Peperomia pellucida increased bone calcium at lowest dose but maintained this parameter at normal range at high dose in fractured rat. Alkaline phophatase and phosphorus concentrations reduced significantly (p < 0.01) at the dose of 400 mg/kg as compared to fractured rats. Moreover, radiological tests revealed a dose dependent formation of callus at the level of the fracture gap, confirmed by the formation of a highly dense and compact fibrocartilagenous callus. The mineral content of the plant extract revealed the presence of calcium, phosphorus, magnesium, sodium and potassium. Conclusion: The aqueous extract of P. pellucida accelerates bone healing due partly to the mineral content of the extract. These results confirm its traditional use in the treatment of bone fractures. © 2017 The Author(s).

PubMed | Centers for Disease Control and Prevention, University of Antananarivo, Central Technical Group, National HIV drug resistance surveillance and prevention Working Group HIVDR WG and 2 more.
Type: Journal Article | Journal: BMC infectious diseases | Year: 2017

In low-income countries (LICs), HIV sentinel surveillance surveys (HIV-SSS) are recommended in between two demographic and health surveys, due to low-cost than the latter. Using the classical unlinked anonymous testing (UAT), HIV-SSS among pregnant women raised certain ethical and financial challenges. We therefore aimed at evaluating how to use prevention of mother-to-child transmission of HIV (PMTCT) routine data as an alternative approach for HIV-SSS in LICs.A survey conducted through 2012 among first antenatal-care attendees (ANC1) in the ten regions of Cameroon. HIV testing was performed at PMTCT clinics as-per the national serial algorithm (rapid test), and PMTCT site laboratory (PMTCT-SL) performances were evaluated by comparison with results of the national reference laboratory (NRL), determined as the reference standard.Acceptance rate for HIV testing was 99%, for a total of 6521 ANC1 (493% aged 15-24) enrolled nationwide. Among 6103 eligible ANC1, sensitivity (using NRL testing as the reference standard) was 812%, ranging from 588% (South region) to 100% (West region); thus implying that 188% HIV-infected ANC1 declared HIV-negative at the PMTCT-SL were positive from NRL-results. Specificity was 993%, without significant disparity across sites. At population-level, this implies that every year in Cameroon, ~2,500 HIV-infected women are wrongly declared seronegative, while ~1,000 are wrongly declared seropositive. Only 444% (16/36) of evaluated laboratories reached the quality target of 80%.The study identified weaknesses in routine PMTCT HIV testing. As Cameroon transitions to using routine PMTCT data for HIV-SSS among pregnant women, there is need in optimizing quality system to ensure robust routine HIV testing for programmatic and surveillance purposes.

Tokam A.-P.K.,University of Yaounde1 | Tabod C.T.,University of Yaounde1 | Nyblade A.A.,Pennsylvania State University | Julia J.,Pennsylvania State University | And 2 more authors.
Geophysical Journal International | Year: 2010

The Cameroon Volcanic Line (CVL) consists of a linear chain of Tertiary to Recent, generally alkaline, volcanoes that do not exhibit an age progression. Here we study crustal structure beneath the CVL and adjacent regions in Cameroon using 1-D shear wave velocity models obtained from the joint inversion of Rayleigh wave group velocities and P-receiver functions for 32 broad-band seismic stations deployed between 2005 January and 2007 February. We find that (1) crustal thickness (35-39 km) and velocity structure is similar beneath the CVL and the Pan African Oubanguides Belt to the south of the CVL, (2) crust is thicker (43-48 km) under the northern margin of the Congo Craton and is characterized by shear wave velocities ≥4.0 km s-1 in its lower part and (3) crust is thinner (26-31 km) under the Garoua rift and the coastal plain. In addition, a fast velocity layer (Vs of 3.6-3.8 km s-1) in the upper crust is found beneath many of the seismic stations. Crustal structure beneath the CVL and the Oubanguides Belt is very similar to Pan African crustal structure in the Mozambique Belt, and therefore it appears not to have been modified significantly by the magmatic activity associated with the CVL. The crust beneath the coastal plain was probably thinned during the opening of the southern Atlantic Ocean, while the crust beneath the Garoua rift was likely thinned during the formation of the Benue Trough in the early Cretaceous. We suggest that the thickened crust and the thick mafic lower crustal layer beneath the northern margin of the Congo Craton may be relict features from a continent-continent collision along this margin during the formation of Gondwana. © 2010 The Authors Geophysical Journal International © 2010 RAS.

Ngounoue F.K.,University of Yaounde1 | Mainsah E.N.,University of Buea | Conde A.M.,University of Douala | Paboudam A.G.,University of Yaounde1 | And 4 more authors.
Der Pharma Chemica | Year: 2015

series of metal complexes have been synthesised using the Schiff base ligand, 4-hydroxypent-3-en-2- ylideneaminophenol, (L1) derived from the condensation reaction of 2-aminophenol with acetyl acetone in ethanol. This series of M-L1 complexes (M=Fe(III),Co(II),Mn(II), Cu(II) and Zn(II) ) were characterized by spectroscopic techniques (IR, UV-visible), elemental analysis, and conductivity measurement. The analytical results reveal that the Schiff base acted as a tridentate ligand and coordinated to the metal ion in a 1:1 M: L stoichiometric ratio. The Fe(III), Mn(II) and Co(II) complexes showed octahedral geometry, while the Zn(II) and Cu(II) complexes showed tetrahedral geometry. Invitro antibacterial activity of the Schiff base ligand and its metal complexes carried out on four bacterial strains (E. coli, P. aeruginosa, S. typhi, S. aureus) and four fungal strains (C. albicans ATCC 12C, C. albicans ATCC P37037, C. albicans ATCC P37039, C. neoformans) showed higher activity of the complexes compared to the ligand. The Schiff base and its metal complexes showed antioxidant (free radical scavenging) activities when compared to garlic acid.

Wanji S.,University of Buea | Wanji S.,Research Foundation for Tropical Diseases and Environment | Kengne-Ouafo J.A.,University of Buea | Kengne-Ouafo J.A.,Research Foundation for Tropical Diseases and Environment | And 18 more authors.
Parasites and Vectors | Year: 2015

Background: Community-Directed Treatment with Ivermectin (CDTI) is the main strategy adopted by the African Programme for Onchocerciasis control (APOC). Recent reports from onchocerciasis endemic areas of savannah zones have demonstrated the feasibility of disease elimination through CDTI. Such information is lacking in rain forest zones. In this study, we investigated the parasitological and entomological indices of onchocerciasis transmission in three drainage basins in the rain forest area of Cameroon [after over a decade of CDTI]. River basins differed in terms of river number and their flow rates; and were characterized by high pre-control prevalence rates (60-98%). Methods: Nodule palpation and skin snipping were carried out in the study communities to determine the nodule rates, microfilarial prevalences and intensity. Simulium flies were caught at capture points and dissected to determine the biting, parous, infection and infective rates and the transmission potential. Results: The highest mean microfilaria (mf) prevalence was recorded in the Meme (52.7%), followed by Mungo (41.0%) and Manyu drainage basin (33.0%). The same trend was seen with nodule prevalence between the drainage basins. Twenty-three (23/39) communities (among which 13 in the Meme) still had mf prevalence above 40%. All the communities surveyed had community microfilarial loads (CMFL) below 10 mf/skin snip (ss). The infection was more intense in the Mungo and Meme. The intensity of infection was still high in younger individuals and children less than 10 years of age. Transmission potentials as high as 1211.7 infective larvae/person/month were found in some of the study communities. Entomological indices followed the same trend as the parasitological indices in the three river basins with the Meme having the highest values. Conclusion: When compared with pre-control data, results of the present study show that after over a decade of CDTI, the burden of onchocerciasis has reduced. However, transmission is still going on in this study site where loiasis and onchocerciasis are co-endemic and where ecological factors strongly favour the onchocerciasis transmission. The possible reasons for this persistent and differential transmission despite over a decade of control efforts using ivermectin are discussed. © 2015 Wanji et al.; licensee BioMed Central.

Mokpidie D.,University of Bangui | Lazar G.,University of Bacau | Faciu E.,University of Bacau | Mossoa L.,University of Bangui | And 3 more authors.
Environmental Engineering and Management Journal | Year: 2014

The paper presents the preliminary results obtained using the Geographic information System (GIS) techniques in the study of vegetation dynamics in a peri-urban area, having as case study the forest in a region of southwestern Central African Republic. The study area concerns a zone located between 4° 00' - 4° 30' North latitude and 18° 15' - 18° 30' East longitude, having a total surface of 156,531 ha, from which 88,547 ha is exploitable area. The satellite images (Landsat TM 1984 images, captured during the dry season, March, and 2008, also captured during the dry season, April), aerial photographs and other support information from 1984 and 2008 were used to realize the two soil occupation maps, separated by 24 years. The results show that the area occupied by forest decreased during the analyzed period by more than 25%, from 148,905 ha to 109,246 ha; the data also indicate a significant increase in the proportion of the degraded forest, from 7,203 ha to 39,329 ha. Even if at this stage the tool does not allow very precise identification of the causes that led to the reduction of area occupied by forest and the decrease of its quality, the database can be completed and used as a policymaker tool. © 2014, (publisher). All rights reserved.

Mainsah E.N.,University of Buea | Ndifon P.T.,University of Yaounde1 | Nfor E.N.,University of Buea | Njapba J.N.,University of Buea
Bulletin of the Chemical Society of Ethiopia | Year: 2013

A new ligand, (1H-pyrrol-2-yl)isonicotinoylhydrazone (Pyr-inh) and its metal complexes have been synthesised and characterized by elemental analyses, IR, 1H and 13C-NMR, UV-Vis spectra, molar conductance, and thermogravimetry-differential thermal analysis (TG-DTA). From the results obtained, the structure of the complexes are of general formula [M(Pyr-inh) 2Cl2].xH2O for M = Co(II), and Zn(II) and [M(Pyrinh) 2(H2O)2]Cl2 for Cu(II). The thermal behaviour of these complexes showed the loss of lattice water in the first step followed by decomposition of the ligand in subsequent steps. The ligand and its transition metal complexes were studied for their in vitro antibacterial activity against ten pathogenic bacterial strains. The data obtained revealed that the ligand was active against Morganella morganii and Escherichia coli, the Co(II) complex active against Klebsiella oxytoca, the Cu(II) complex showed significant activity against five out of the ten bacterial strains and the Zn(II) complex was active against all the pathogenic bacterial strains investigated. © 2013 Chemical Society of Ethiopia.

Kenfack C.,University of Yaounde I | Kenfack C.,University of Yaounde1 | Kenfack C.,University of Quebec at Montréal
ICSOFT 2013 - Proceedings of the 8th International Joint Conference on Software Technologies | Year: 2013

This paper presents the implementation of an intelligent tutoring system (ITS) using the Jade agents intermediation system (AIS) for community of practice to support knowledge emergence and sharing in collaborative learning situation The key component is the community of practices model which will be derived from monitoring the knowledge sharing process . These issues are important in Learning community like a CoPs (both in educational and organisational context), as they promote the processes of knowledge sharing, collaborative learning, and development of collective efficacy among community members. The system kernel o f AI S supports two types of agents (human agent and artificial agents) that help to manage the collaborative learning activity into the community, whereas the integration mechanism supports an agent to interact, coordinate and monitor the activities between agents. AIS for CoPS facilitate the team interaction.This work takes place in the framework of the design of a training environment using collaborative reality like community of practice. In this context, we defend the thesis that it is possible to implement a generic and adaptive intelligent tutoring system (called ITAgAGS) in a collaborative environment, in order to provide pedagogical aid for the learner and pedagogical assistance for the trainer. Our proposal is to integrate ITS in a multi-agent system like JAIS developed during our thesis. Copyright © 2013 SCITEPRESS.

Lontsi F.,University of Douala | Hamandjoda O.,University of Yaounde1 | Fozao K.,University of Buea | Stouffs P.,University of Pau and Pays de l'Adour | Nganhou J.,University of Yaounde1
Energy | Year: 2013

The Ericsson engine is an external combustion engine suitable for the use of certain energy sources such as solar energy, biomass and waste gases at high temperature, and thus contributes to the fight against global warming. Its open cycle configuration considered in this study can achieve good performance in low power range, most particularly in micro-cogeneration applications. The dynamic model of this engine which is the purpose of this study, takes into account both the pressure losses and the variation of the thermophysical properties of the working fluid as a function of the temperature in the system. The coded models are implemented on a Matlab/Simulink platform where the start-up dynamics and performance simulations are conducted. The optimal settings of the expansion cylinder valves, as well as the characteristic parameters of the engine are thus determined. In this configuration the engine develops a power output of 1.72kW and reacts well when subjected to a selected perturbation. © 2013 Elsevier Ltd.

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