Anastasia N. Guantai

Establishment of a biobank and pharmacogenetics database of African populations

Pharmacogenetics and genomics research has experienced great advances over the past decade as witnessed by the completion of the human genome in 2003 (www.genome.gov/HGP). The field has been driven by the belief that understanding the human genome, that of pathogens, and interindividual genetic variability would result in radical advances in medicine. Anticipated measurable end points include increased targets for which drug discovery campaigns could be initiated, increased understanding of human susceptibility to disease and variability in drug response hence development of diagnostic tools to realize individualized treatment where drugs would be given to patients in whom they are predicted to work and at doses predicted to be safe.1 Toward the realization of this biomedical paradigm, Biobanking and Pharmacogenetics Databasing have become well established in developed countries (www.biobanks.se, www.icelandbio.com, www.ukbiobank.ac.uk). Little has, however, been done in developing countries.2 Starting with a workshop organized by the African Institute of Biomedical Science and Technology (www.aibst.com) in 2003 on Pharmacogenetics of Drug Metabolism in Nairobi, Kenya, a number of African scientists initiated a consortium for the biobanking and pharmacogenetics databasing of African populations. We here report the results of the first phase of this initiative that has seen research groups from five different African countries with collaborative support from leading experts in Europe and America establish a biobank of blood and DNA from nine ethnic groups from across the African continent. The biobank of anonymous samples has been used to establish baseline frequency distribution of SNPs of genes important in drug metabolism, hence the initiation of a pharmacogenetics database (http://www.aibst.com/biobank.html).

Analysis of pan-African Centres of excellence in health innovation highlights opportunities and challenges for local innovation and financing in the continent

A pool of 38 pan-African Centres of Excellence (CoEs) in health innovation has been selected and recognized by the African Network for Drugs and Diagnostics Innovation (ANDI), through a competitive criteria based process. The process identified a number of opportunities and challenges for health R&D and innovation in the continent: i) it provides a direct evidence for the existence of innovation capability that can be leveraged to fill specific gaps in the continent; ii) it revealed a research and financing pattern that is largely fragmented and uncoordinated, and iii) it highlights the most frequent funders of health research in the continent. The CoEs are envisioned as an innovative network of public and private institutions with a critical mass of expertise and resources to support projects and a variety of activities for capacity building and scientific exchange, including hosting fellows, trainees, scientists on sabbaticals and exchange with other African and non-African institutions.

In Vitro Antiplasmodial Activities and Synergistic Combinations of Differential Solvent Extracts of the Polyherbal Product, Nefang

Nefang, a polyherbal product composed of Mangifera indica (bark and leaf), Psidium guajava, Carica papaya, Cymbopogon citratus, Citrus sinensis, and Ocimum gratissimum (leaves), is a potential therapy against P. falciparum malaria. In vitro antiplasmodial activities of its constituent solvent extracts were analyzed on CQ-sensitive (3D7) and multidrug resistant (Dd2) P. falciparum strains. The interactions involving the differential solvent extracts were further analyzed using a variable potency ratio drug combination approach. Effective concentration 50 (EC50) values were determined by nonlinear regression curve-fitting of the dose-response data and used in calculating the fractional inhibitory concentration 50 (FIC50) and combination indices (CI) for each pair. The derived EC50 values (3D7/Dd2, μg/mL) are Nefang-96.96/55.08, MiB-65.33/34.58, MiL-82.56/40.04, Pg-47.02/25.79, Cp-1188/317.5, Cc-723.3/141, Cs-184.4/105.1, and Og-778.5/118.9. Synergism was obtained with MiB/Pg (CI = 0.351), MiL/Pg (0.358), MiB/Cs (0.366), MiL/Cs (0.482), Pg/Cs (0.483), and Cs/Og (0.414) when analyzed at equipotency ratios. Cytotoxicity testing of Nefang and the solvent extracts on two human cell lines (Hep G2 and U2OS) revealed no significant toxicity relative to their antiplasmodial activities (SI > 20). Taken together, our data confirm the antimalarial activities of Nefang and its constituent plant extracts and identified extract pairs with promising synergistic interactions for exploitation towards a rational phytotherapeutic and evidence-based antimalarial drug discovery.

Anti-malarial activity of a polyherbal product (Nefang) during early and established Plasmodium infection in rodent models

BackgroundThe emerging resistance of Plasmodium species to currently available anti-malarials remains a public health concern, hence the need for new effective, safe and affordable drugs. Natural products remain a reliable source of drugs. Nefang is a polyherbal anti-malarial of the Cameroonian folklore medicine with demonstrated in vitro antiplasmodial and antioxidant activities. It is composed of Mangifera indica (bark and leaf), Psidium guajava, Carica papaya, Cymbopogon citratus, Citrus sinensis, Ocimum gratissimum (leaves). This study aimed at investigating the suppressive, prophylactic and curative activities of Nefang in Plasmodium infected rodent models.MethodsSystemic acute oral toxicity of Nefang aqueous and ethanol extracts was assessed in mice up to a dose of 5,000 mgkg−1 body weight. BALB/c mice and Wistar rats were inoculated with Plasmodium chabaudi chabaudi and Plasmodium berghei, respectively, and treated with Nefang, the Mangifera indica bark/Psidium guajava combination and a Psidium guajava leaf aqueous extracts (75, 150, 300 and 600 mgkg−1 bwt). Their schizonticidal activity was then evaluated using the Peter’s 4-day suppressive test). The prophylactic and curative (Rane’s Test) activity of Nefang was also evaluated by determining the parasitaemia, survival time, body weight and temperature in pre-treated rodents.ResultsAcute oral toxicity of the extract did not cause any observed adverse effects. Percent suppressions of parasitaemia at 600 mgkg−1 bwt were as follows (P. berghei/P. chabaudi): Nefang – 82.9/86.3, Mangifera indica bark/Psidium guajava leaf combination extract – 79.5/81.2 and Psidium guajava leaf – 58.9/67.4. Nefang exhibited a prophylactic activity of 79.5% and its chemotherapeutic effects ranged from 61.2 – 86.1% with maximum effect observed at the highest experimental dose.ConclusionThese results indicate that Nefang has excellent in vivo anti-malarial activities against P. berghei and P. chabaudi, upholding earlier in vitro antiplasmodial activities against multi-drug resistant P. falciparum parasites as well as its traditional use. Hence, Nefang represents a promising source of new anti-malarial agents.

Pharmacological evidence for the folk use of Nefang: antipyretic, anti-inflammatory and antinociceptive activities of its constituent plants.

BackgroundNefang is a polyherbal anti-malarial composed of Mangifera indica (MiB and MiL; bark and leaf), Psidium guajava (Pg), Carica papaya (Cp), Cymbopogon citratus (Cc), Citrus sinensis (Cs) and Ocimum gratissimum (Og) (leaves). Previous studies have demonstrated its in vitro and in vivo antiplasmodial activities, antioxidant properties and safety profile. This study aimed at evaluating the antipyretic, anti-inflammatory and antinociceptive activities of the constituent plants of Nefang which are relevant to the symptomatic treatment of malaria fever.MethodsAntipyretic activities were determined by the D-Amphetamine induced pyrexia and Brewer’s Yeast induced hyperpyrexia methods. Anti-inflammatory activities were investigated using the carrageenan-induced rat paw edema method. Antinociceptive activities were determined by mechanical nociception in the tail pressure and thermal nociception in the radiant heat tail flick and hot plate methods. Data was analysed using the one way ANOVA followed by Neuman-Keuls multiple comparison test.ResultsBest percentage inhibition of induced pyrexia (amphetamine/brewer’s yeast; p < 0.05) was exhibited by Cc (95/97) followed by Og (85/94), MiL (90/89), MiB (88/84) and Cs (82/89). Cc and Og exhibited comparable activities to paracetamol (100/95).Anti-inflammatory studies revealed paw edema inhibition (%) as follows (p < 0.05): Indomethacin (47), MiL (40), Cp (30), MiB (28) and Og (22), suggesting best activity by MiL.Antinociceptive studies revealed significant (p < 0.01) pain inhibition (%) as follows: Paracetamol (97), Og (113), MiL (108), Pg (84) and MiB (88). Og and MiL exhibited the best activities.ConclusionThe results obtained suggest that the constituent plants possess biologically active compounds with antipyretic, anti-inflammatory and antinociceptive activities. These activities are essential in the symptomatic treatment of malaria fever, thereby justifying the folk use of Nefang. This would be useful in its subsequent development for clinical application.

Antioxidant potential of a polyherbal antimalarial as an indicator of its therapeutic value.

Nefang is a polyherbal product composed of Mangifera indica (bark and leaf), Psidium guajava, Carica papaya, Cymbopogon citratus, Citrus sinensis, and Ocimum gratissimum (leaves), used for the treatment of malaria. Compounds with antioxidant activity are believed to modulate plasmodial infection. Antioxidant activity of the constituent aqueous plants extracts, in vitro, was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), total phenolic content (TPC), and ferric reducing antioxidant power (FRAP) methods and, in vivo, Nefang (100 and 500 mg kg−1) activity was evaluated in carbon tetrachloride-induced oxidative stressed Wistar rats. Superoxide dismutase, catalase activities, and lipid peroxidation by the malondialdehyde and total proteins assays were carried out. P. guajava, M. indica leaf, and bark extracts had the highest antioxidant properties in all three assays, with no statistically significant difference. Rats treated with the carbon tetrachloride had a statistically significant decrease in levels of triglycerides, superoxide dismutase, and catalase (P < 0.05) and increase in malondialdehyde activity, total protein levels, and liver and renal function markers, whereas rats treated with Nefang showed increased levels in the former and dose-dependent decrease towards normal levels in the later. These results reveal the constituent plants of Nefang that contribute to its in vivo antioxidant potential. This activity is a good indication of the therapeutic potential of Nefang.

Management of Type 2 Diabetes Mellitus by Traditional Medicine Practitioners in Kenya- Key Informant Interviews

Introduction Worldwide, plant based medicines are increasing in popularity due to perceptions of safety and efficacy. Herbalists in Kenya are widely consulted for the management of many diseases including Type 2 Diabetes Mellitus (T2DM). This study investigated the level of knowledge of the herbalists in management of T2DM. Methods Purposive sampling was used to identify 4 herbalists working in the urban areas who actively manage T2DM. Key informant interviews were used to gather data about the management of T2DM. It was analyzed using a content thematic approach. Results Diverse management methods which included both pharmacological and non- pharmacological were noted. Glycemic control was assessed with the help of a glucometer. In addition, presenting signs and symptoms were key in diagnosing T2DM. The herbalists used various herbs, minerals and animals as medicinal sources. The drugs were dispensed as decoctions with excipients being added appropriately. Adverse effects were recorded. The herbalists acknowledged that patients use both herbal and allopathic medicine together. A level of record keeping was observed but patient follow-up was poor. The cost of the herbal drugs was perceived to be excessive. Conclusion Some similarities exist in the management of T2DM between allopathic and traditional medicine practitioners. Training of herbalists is required to improve the quality of care given to patients.

Effects of the active constituents of Catha edulis on the neuromuscular junction

(-)-Cathinone and d-norpseudoephedrine (DNE) in the dose range 0.2-1.2 mg/ml produced a reduction in contractions of skeletal muscle, evoked by direct and indirect electrical stimulation and antagonised the facilitatory action of physostigmine on the neuromuscular junction; but failed to antagonise a partial blockade induced by d-tubocurarine (dTb) as occurs with norepinephrine or epinephrine. The local anaesthetic actions of (-)-cathinone and DNE were found to be almost equivalent to that of lignocaine. These results indicate that (-)-cathinone and DNE may have a direct blocking action on the neuromuscular junction, which is independent of cholinergic and adrenergic transmission.

Impact of First Line Antiretroviral Therapy on Clinical Outcomes Among HIV-1 Infected Adults Attending One of the Largest HIV Care and Treatment Program in Nairobi Kenya

Objective: This study evaluated the immunologic (CD4 cell count), virological (HIV RNA viral load), hepatic (alanine and aspartate aminotransferase - ALT and AST), renal (creatinine) and hematological (hemoglobin -HB, White Blood Cell - WBC, Lymphocytes - LYM and platelets - PLT) response to a six months ART treatment among HIV participants in Nairobi Kenya. Methods: Blood samples were obtained from 599 consenting HIV infected participants receiving HIV treatment in Nairobi. CD4 cell counts were measured using flow cytometer and viral load determined using real-time polymerase chain reaction. The blood hematology, liver and kidney function tests were also measured. One-way ANOVA and Linear regression analysis were conducted. Results: The median age at ART initiation was 41 years (IQR 35-47 years). The majority of participants (60.3%) were female and 56.1% started on regimens with 2 NRTIs and efavirenz based NNRTI. About 40% of the participants were failing treatment 6 month post ART initiation. The CD4 count significantly increased at the 6-month post ART initiation (301.7 ± 199.4 to 329.4 ± 305.8; P 5 times the upper limit of normal - ULN) and renal abnormalities (elevated serum creatinine levels) were all high at month 6 compared to baseline; ALT (2.5 to 10.5%), AST (5.3 to 23.4%) and creatinine (63.4 to 68.84%). Fewer participants at month 6 had anemia (29.4% verses 56.4%), leucopenia (42.4% vs. 46.9%) and thrombocytopenia (6.5% vs. 84.1%) compared to baseline. In multivariable models, baseline levels of this parameter, ART regimen and duration with HIV at ART initiation were the most important determinant of month 6 levels. Conclusion: These data demonstrate sustained immunologic/virologic response to ART among participants remaining on therapy. Anemia, leucopenia and thrombocytopenia were minimized with marginal hepatotoxicity and renal impairment seen. Interventions leading to earlier HIV diagnosis and initiation of ART could substantially improve patient outcomes in Kenya.

What Makes International Global Health University Partnerships Higher-Value? An Examination of Partnership Types and Activities Favoured at Four East African Universities

Background: There are many interuniversity global health partnerships with African universities. Representatives of these partnerships often claim partnership success in published works, yet critical, contextualized, and comparative assessments of international, cross-border partnerships are few. Objective: The objectives of this paper are to describe partnerships characterized as higher-value for building the capacity of four East African universities and identify why they are considered so by these universities. Methods: Forty-two senior representatives of four universities in East Africa described the value of their partnerships. A rating system was developed to classify the value of the 125 international partnerships they identified, as the perceived value of some partnerships varied significantly between representatives within the same university. An additional 88 respondents from the four universities and 59 respondents from 25 of the international partner universities provided further perspectives on the partnerships identified. All interviews were transcribed and analysed in relation to the classification and emergent themes. Findings: Thirty-one (25%) of the partnerships were perceived as higher-value, 41 (33%) medium-value, and 53 (42%) lower-value for building the capacity of the four focus universities. Thirteen (42%) of the higher-value partnerships were over 20 years old, while 8 (26%) were between 3 and 5 years old. New international partners were able to leapfrog some of the development phases of partnerships by coordinating with existing international partners and/or by building on the activities of or filling gaps in older partnerships. Higher-valued partnerships supported PhD obtainment, the development of new programmes and pedagogies, international trainee learning experiences, and infrastructure development. The financial and prestige value of partnerships were important but did not supersede other factors such as fit with strategic needs, the development of enduring results, dependability and reciprocity. Support of research or service delivery were also considered valuable but, unless education components were also included, the results were deemed unlikely to last. Conclusion: International partnerships prioritizing the needs of the focus university, supporting it in increasing its long-term capacity and best ensuring that capacity benefits realized favour the focus university are valued most. How best to achieve this so all partners still benefit sufficiently requires further exploration.