In Vitro Antiplasmodial Activity and Cytotoxicity of Extracts of Selected Medicinal Plants Used by Traditional Healers of Western Cameroon

Medicinal plants play a key role in malaria control in Africa, especially in remote areas where health facilities are limited. In order to assess their acclaimed potentials, eleven extracts were prepared from seven selected plants commonly used in Western Cameroon, and tested both for their antiplasmodial activity and cytotoxicity. The antiplasmodial activity was assessed using Lactate Dehydrogenase Assay (pLDH) and the cytotoxicity estimated on LLC-MK2 monkey kidney epithelial cells. Seven extracts from five different plants were significantly active, with very weak or no cytotoxicity. The Dacryodes edulis leaves showed the highest activity (IC50 of 6.45 μg/mL on 3D7 and 8.2 μg/mL on DD2) followed by the leaves of Vernonia amygdalina (IC50 of 8.72 and 11.27 μg/mL on 3D7 and DD2 resp.) and roots of V. amygdalina (IC50 of 8.72 μg/mL on 3D7), Coula edulis leaves (IC50 of 13.80 μg/mL and 5.79 μg/mL on 3D7 and DD2 resp.), Eucalyptus globulus leaves (IC50 of 16.80 μg/mL and 26.45 μg/mL on 3D7 and DD2) and Cuviera longiflora stem bark (IC50 of 20.24 μg/mL and 13.91 μg/mL on 3D7 and DD2). These findings justify the use of five of the seven plants in malaria treatment by traditional healers of Western Cameroon

Molecular cloning and differential IgG responses to a histidine-rich antigen (OvL3.C1) of Onchocerca volvulus by selected residents of onchocerciasis endemic regions in Cameroon and Ecuador

In order to further investigate host-parasite interactions in onchocerciasis, a major Onchocerca volvulus histidine rich antigen termed OvL3.C1 was isolated from an O. volvulus cDNA library using antibodies from putatively immune subjects living in onchocerciasis endemic communities in Cameroon. Analysis of its sequences predicted the protein to be helix-rich with a single transmembrane region. Recombinant OvL3.C1 antigen induced from pBAD-TOPO/Thio vector in Escherichia coli was purified as inclusion bodies and further by a combination of Ni2+ chelate chromatography and electroelution. Anti-OvL3.C1 immunoglobulin G (IgG) subclass levels were assessed by ELISA in 15 pairs and 18 pairs of selected and cross-matched infected and putatively immune subjects from Cameroon and Ecuador, respectively. IgG3 and IgG4 levels were shown to be significantly higher in putatively immune (immune protected) subjects. A higher IgG3 level in endemic normal subjects is implicated in parasite killing and the development of the putative immune status while IgG4 has been shown to block onchocercal pathology. OvL3.C1 is a dominant antigen in onchocerciasis which elicits strong responses in subjects expose to both African and South American forms of onchocerciasis. It is therefore an important player in mechanisms of resistance or allergy attenuation in onchocerciasis.Keywords: Onchocerciasis, immunoglobulin G, putative immunit

Antiplasmodial activities of some products from Turreanthus africanus (Meliaceae)

We investigated the antiplasmodial activity of some pure compounds of Turreanthus africanus (Meliaceae), a plant that is used in traditional medicine to treat malaria in Southwest Cameroon. A phytochemical analysis of the methylene chloride: methanol (1:1) extract of the seeds of the plant yielded seven compounds. Four of them, which were oils, were subjected to in vitro bioassays on Plasmodium falciparum F 32, chloroquine sensitive strain. Compound 1 (16-oxolabda-8 (17), 12(E)-dien-15-oic acid), showed the highest antiplasmodial activity, two others (methyl-14,15-epoxylabda-8 (17), 12(E)-diene-16-oate, and turreanin A), had moderate activity and one was inactive. These findings are consistent with the use of T. africanus in the traditional treatment of P. falciparum malaria. African Journal of Health Sciences Vol. 13 (1-2) 2008: pp. 32-3

Creating a best practice template for participant communication plans in global health clinical studies

Background Clinical trial participants have a right to be informed throughout the entire process of human subject research. As part of this pillar of research ethics, participants and other stakeholders should be made aware of research findings after a trial has been completed. Though participants have both a right, and a desire to be informed of research outcomes, studies show that they rarely receive communication about study findings. Our aim was (1) to understand what, if any, role communication plans play in current global health clinical research protocols and (2) to use our findings to develop a communication plan template tailored to clinical research carried out in low-and-middle-income countries (LMIC) while minimizing colonial assumptions. While the template was drafted in the LMIC context, the principles are universally applicable and should be considered best practices for all global health clinical trials. Methods We carried out a mixed-method study over a period of 6 months to understand the role of communication with study participants and other stakeholders in clinical trials. The semiquantitative analysis included mining publicly available clinical trial protocols for communication-related language. Qualitative interviews (n = 7) were used to gather knowledge and insight from clinical trial experts to inform the development of a communication plan template. Results None of the 48 mined clinical trial protocols included a communication plan. Of the 48, 21% (n = 21) protocols included communication-related language, and 10% (n = 5) described plans to share trial results with participants. Conclusion The use of communication plans in global health clinical trials is lacking. To our knowledge, this is the first in-depth analysis of communication plans in clinical trials to date. We recommend that researchers utilize the developed communication plan template throughout the entire research process to ensure a human-centered approach to participant communication. This communication plan should apply to all phases of a research trial, with a particular emphasis on plans to share results in an accessible and engaging manner once the trial has been completed

Haematological changes and recovery associated with treated and untreated Plasmodium falciparum infection in children in the Mount Cameroon Region

Pre-hospital antimalarial treatment of febrile children remains a significant common practice among individuals in the Mount Cameroon region. To evaluate the effect of routinely administered monotherapy sulphadoxine pyrimethamine (SP), treatment using amodiaquine artesunate (AQAS) combination therapy and untreated malaria on haematological and parasitological parameters, 332 malaria positive subjects were assigned to three groups comprising 138 children treated with AQAS, 43 treated with SP and 151 untreated. The changes and recovery in red cell indices, white blood cell and differential and platelets counts were compared. The highest haematological recovery (39.1%) occurred in the AQAS treatment group. The majority (94%) of the untreated cases never achieved haematological recovery even though there was spontaneous clearance of parasites in some cases. Haematological insult was greatest in untreated children followed by those treated with SP, the 1.1 -3 year age group whether or not they received treatment and in those with high parasitaemia. Delayed parasite clearance observed in the untreated and SP treatment group may be responsible for the occurrence of haematological insult. Treatment type and parasitological cure was associated with haematological recovery. Prompt use of effective arthemisinin combination therapy reduced the burden of malaria, hence the greater clinical and haematological benefits observed in our study

Mycobacterium tuberculosisis the causative agent of tuberculosis in the southern ecological zones of Cameroon, as shown by genetic analysis

BACKGROUND: Tuberculosis (TB) is a major cause of mortality and suffering worldwide, with over 95% of TB deaths occurring in low- and middle-income countries. In recent years, molecular typing methods have been widely used in epidemiological studies to aid the control of TB, but this usage has not been the case with many African countries, including Cameroon. The aims of the present investigation were to identify and evaluate the diversity of the Mycobacterium tuberculosis complex (MTBC) isolates circulating in two ecological zones of Cameroon, seven years after the last studies in the West Region, and after the re-organization of the National TB Control Program (NTBCP). These were expected to shed light also on the transmission of TB in the country. The study was conducted from February to July 2009. During this period, 169 patients with symptomatic disease and with sputum cultures that were positive for MTBC were randomly selected for the study from amongst 964 suspected patients in the savannah mosaic zone (West and North West regions) and the tropical rainforest zone (Central region). After culture and diagnosis, DNA was extracted from each of the MTBC isolates and transported to the BecA-ILRI Hub in Nairobi, Kenya for molecular analysis. METHODS: Genetic characterization was done by mycobacterial interspersed repetitive unit–variable number tandem repeat typing (MIRU-VNTR) and Spoligotyping. RESULTS: Molecular analysis showed that all TB cases reported in this study were caused by infections with Mycobacterium tuberculosis (98.8%) and Mycobacterium africanum (M. africanum) (1.2%) respectively. We did not detect any M. bovis. Comparative analyses using spoligotyping revealed that the majority of isolates belong to major clades of M. tuberculosis: Haarlem (7.6%), Latin American-Mediterranean (34.4%) and T clade (26.7%); the remaining isolates (31.3%) where distributed among the minor clades. The predominant group of isolates (34.4%) corresponded to spoligotype 61, previously described as the “Cameroon family. Further analysis based on MIRU-VNTR profiles had greater resolving power than spoligotyping and defined additional genotypes in the same spoligotype cluster. CONCLUSION: The molecular characterization of MTBC strains from humans in two ecological regions of Cameroon has shown that M. tuberculosis sensu stricto is the predominant agent of TB cases in the zones. Three decades ago, TB was reported to be caused by M. africanum in 56.0% of cases. The present findings are consistent with a major shift in the prevalence of M. tuberculosis in Cameroon

Antiplasmodial Activities of Some Products from Turreanthus Africanus (Meliaceae)

We investigated the antiplasmodial activity of some pure compounds of Turreanthus africanus (Meliaceae), a plant that is used in traditional medicine to treat malaria in Southwest Cameroon. A phytochemical analysis of the methylene chloride: methanol (1:1) extract of the seeds of the plant yielded seven compounds. Four of them, which were oils, were subjected to in vitro bioassays on Plasmodium falciparum F 32, chloroquine sensitive strain. Compound 1 (16-oxolabda-8 (17), 12(E)-dien-15-oic acid), showed the highest antiplasmodial activity, two others (methyl-14,15-epoxylabda-8 (17), 12(E)-diene-16-oate, and turreanin A), had moderate activity and one was inactive. These findings are consistent with the use of T. africanus in the traditional treatment of P. falciparum malaria

CD27− B-Cells Produce Class Switched and Somatically Hyper-Mutated Antibodies during Chronic HIV-1 Infection

Class switch recombination and somatic hypermutation occur in mature B-cells in response to antigen stimulation. These processes are crucial for the generation of functional antibodies. During HIV-1 infection, loss of memory B-cells, together with an altered differentiation of naïve B-cells result in production of low quality antibodies, which may be due to impaired immunoglobulin affinity maturation. In the current study, we evaluated the effect of HIV-1 infection on class switch recombination and somatic hypermutation by studying the expression of activation-induced cytidine deaminase (AID) in peripheral B-cells from a cohort of chronically HIV-1 infected patients as compared to a group of healthy controls. In parallel, we also characterized the phenotype of B-cells and their ability to produce immunoglobulins in vitro. Cells from HIV-1 infected patients showed higher baseline levels of AID expression and increased IgA production measured ex-vivo and upon CD40 and TLR9 stimulation in vitro. Moreover, the percentage of CD27−IgA+ and CD27−IgG+ B-cells in blood was significantly increased in HIV-1 infected patients as compared to controls. Interestingly, our results showed a significantly increased number of somatic hypermutations in the VH genes in CD27− cells from patients. Taken together, these results show that during HIV-1 infection, CD27− B-cells can also produce class switched and somatically hypermutated antibodies. Our data add important information for the understanding of the mechanisms underlying the loss of specific antibody production observed during HIV-1 infection