Joseph Nganga - Academia.edu (original) (raw)

Papers by Joseph Nganga

this is a retrospective study using stored blood culture isolates to compare the diagnostic techn... more this is a retrospective study using stored blood culture isolates to compare the diagnostic techniques in identification of bloodstream infection; the techniques under analysis are FilmArray polymerase chain reaction machine and MicroScan 40 plus machine compared with Analytical profile index which is routinely used in developing countries as a gold standard for identification of blood culture.In this study we are trying to establish which technique is suitable for diagnosis of bloodstream infection in terms of senstivity, accuracy, turn around time and cost

this is a retrospective study using stored blood culture isolates to compare the diagnostic techn... more this is a retrospective study using stored blood culture isolates to compare the diagnostic techniques in identification of bloodstream infection; the techniques under analysis are FilmArray polymerase chain reaction machine and MicroScan 40 plus machine compared with Analytical profile index which is routinely used in developing countries as a gold standard for identification of blood culture.In this study we are trying to establish which technique is suitable for diagnosis of bloodstream infection in terms of senstivity, accuracy, turn around time and cost

Promouvoir les énergies renouvelables pour satisfaire les besoins en électricité du continent Fév... more Promouvoir les énergies renouvelables pour satisfaire les besoins en électricité du continent Février 2013 Une version pdf (1,8 MB) est téléchargeable en français et en anglais à l’adresse

Certain breeds of domestic ruminants show remarkable resistance to the effects of African trypano... more Certain breeds of domestic ruminants show remarkable resistance to the effects of African trypanosomosis. Unlike susceptible animals, trypanotolerant animals control parasitemia and do not show severe anaemia or production loss. Identification of trypanotolerance genes in cattle is hampered by cost and breeding time. Marked differences between inbred strains of mice in their response to T. congolense infection can be exploited in the analysis of the genetic basis of the infection. Murine trypanotolerance QTLs have been identified on chromosome 17, 5 and 1, and designated as Tir1, 2 and 3, respectively. Tir1 and 2 have been fine mapped to a confidence interval of 1 cM. In order to find the mouse homologous region on the bovine genome, nucleotide sequence across 95 % CI of Tir2 and 3 were used in the selection of candidate genes. Homologous sequences were used in the definition of synteny relationships and subsequent identification of the shared disease response genes. The homologous ...

Rice is an important grain food crop being a staple food for a large part of the world's huma... more Rice is an important grain food crop being a staple food for a large part of the world's human population. Anendophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its lifewithout causing apparent disease. In this study, bioprospecting for bacterial rice root endophytes was explored. 66bacterial pure isolates were isolated from the 138 root samples collected from farmers’ and research fields. Theywere morphologically characterized and screened for biological activities. All isolates were gram negative rods.Two phosphates were used for phosphate solubilisation, in which case more positive response was observed incalcium phosphate than in Alluminium phosphate. Nine isolates were identified to produce IAA- indoleacetic acidimplying potential to enhance plant growth. All isolates tested negative for denitrification test. The biochemicaltests carried out helped reduce the number of isolates from 66 to 30 upon similarity and uniquenes...

Journal of Ethnopharmacology, 2016

Background:The emergence and spread of drug resistance of the malaria parasite to the main treatm... more Background:The emergence and spread of drug resistance of the malaria parasite to the main treatment emphasis the need to develop new antimalarial drugs. In this context, the fatty acid biosynthesis (FAS_II) pathway of the malaria parasite is one of the ideal target due to its crucial role in parasite survival.Method:We report in this study the expression and the affinity binding of two Fab enzymes (FabI and FabZ) after exposure of the parasite using different extracts of the Artemisia afra and after a virtual screening with the different plant compounds. Two differents strains of Plasmodium falciparum was used: W2 (CQ_resistant) and D6 (CQ_sensitive) with a parasiteamia of 4%. The parasites were exposed during 2 days to different Artemisia afra extracts . Gene expression was done to determine the level of expression of the fab enzymes after treatments. A GCMS was run to determine the different compounds of the plant extracts following by a virtual screening between the fab enzymes ...

F1000Research

Background: Bloodstream infection (BSI) contributes to a substantial proportion of mortality in s... more Background: Bloodstream infection (BSI) contributes to a substantial proportion of mortality in sub-Saharan Africa and is marked by the presence of bacterial and/or fungal microorganisms in the blood. Because BSI can be life threatening, it requires a timely, reliable and accurate diagnosis. This study retrospectively analyzed data of identified BSI pathogens and compared the performance of the different diagnostic technologies used in terms of accuracy, sensitivity, turnaround time (TAT) and cost. Methods: Currently, culture followed by analytical profile index biochemical strips (API), (BioMerieux) are used as the conventional standard diagnostics in Kenyan public hospitals and labs. We compared the results of this standard to that of the BioFire FilmArray (FA) (BioFire Diagnostics) and MicroScan WalkAway-40 plus System (MS) (Beckman Coulter) used in diagnosis of BSI. The FA technology was able to identify 150/152 bacterial and yeast isolates with an overall accuracy of 99.04% (95...

Chemistry – An Asian Journal

We demonstrated the photoredox catalytic performances of fluorescein derivatives, bearing heavy h... more We demonstrated the photoredox catalytic performances of fluorescein derivatives, bearing heavy halogen atoms (Br or I) on a benzoic acid group, using photoinitiated free-radical polymerization. 4,5,6,7-Tetrabromofluorescein and 4,5,6,7-tetraiodofluorescein were used as visible-light-photoredox catalysts to initiate polymerization of poly(ethylene glycol) diacrylate and N-vinylpyrrolidone in the presence of triethanolamine under aerobic conditions. Their photocatalytic performances were evaluated by the hydrogelation of photopolymerization both on the surface of an agarose film and in a liquid solution. The polymerization degree increased considerably in the following order: tetraiodofluorescein < tetrabromofluorescein < fluorescein. This result was different from fluorescein derivatives containing the heavy halogen atoms on a xanthene core ring. Consequently, the location of the heavy halogen atoms was crucial in the photocatalytic performance of fluorescein derivatives.

Chemistry – An Asian Journal

American Journal of Laboratory Medicine

Pre-clinical transmission assays are essential for proof-of-concept for transmission blocking str... more Pre-clinical transmission assays are essential for proof-of-concept for transmission blocking strategies but are hazardous to laboratory personnel and animal hosts as it entails exposure of live rodents to infected vectors. Conventional transmission assay methods include the use of anesthesia (associated with undesired side effects). In addition, animal handlers risk being bitten by experimental animals and vectors during anesthesia due to a lack of safe and effective alternatives. Robustness of rodent to vector transmission was determined by comparing the number of oocysts. Vector-to-rodent transmission was determined by measuring parasitemia, gametocytemia, changes in body weight and survival time. A completely randomized design was used in this study. Rodent-to-vector transmission was analyzed by log linear model. Fecundity, gametocytemia, parasitaemia and changes in body weight were analyzed by regression analysis. Survival times were analyzed Kaplan-Meier method for determination of survival distribution function. Rank test of homogeneity were used to determine the effect of restraining method infection on survival times. There was no significant difference (p<0.001) in fecundity of mosquitoes fed on anesthetized mice; 122±22.1 eggs compared to INFECTRA®-Kit group with 110±14.1 eggs. Oocyst production increased gradually though not significantly (p<0.001) in both groups of mice with the number of mosquitoes. The INFECTRA®-Kit group increased from 2.7%±0.3 (1 mosquito) to 9.3%±0.3 (6 mosquitoes), the conventional group was 3.7%±0.3 to 8.6%±0.3 (6 mosquitoes). Parasitemia progression was characterized by two waves in INFECTRA®-Kit and three waves in the conventional group. The highest parasitaemia peak was 22% attained on 22dpi for the INFECTRA®-Kit and 17.8% attained on 26 dpi for the conventional group. Gametocytes were detected on 16 dpi in both groups and thereafter increased significantly (p<0.001) with dpi. In the INFECTRA®-Kit group, gametocytemia was represented by two oscillations while the conventional group was three cycles with peak gametocytes increasing with each subsequent peak. Disease progression was higher and survival times shorter with INFECTRA ®-Kit than with anesthetized mice and there was no significant difference (p<0.05) between the two methods in body weight and gametocytemia. INFECTRA ®-Kit is equivalent to that of anesthesia method but more advantageous given the more ethical and humane treatment of animals.

Pan African Medical Journal

Introduction: glucose 6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy ... more Introduction: glucose 6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy with a relatively high frequency in malariaendemic regions. In Eritrea, there is scanty knowledge of G6PD deficiency. The aim of the study was to characterize and determine the prevalence of four common G6PD allelic variants. Methods: three hundred and fourteen dried blood spot samples from unrelated microscopically diagnosed malaria patient Eritrean ethnic groups living in five zobas (regions) of Eritrea were analysed by PCR-RFLP method to identify the G6PD B, G6PD A (A376G), G6PD A-(G202A), and G6PD Mediterranean (C563T) variants. To confirm the RFLP results, samples positive for A376G but negative for G202A variants were subjected to Sanger sequencing and a subset of PCR products (exon 5) directly sequenced to identify A376G and other mutations. Results: for G6PD genotyping, G6PD B was detected in 87.5% and A376G detected in 12.5% of malaria patients, whereas G202A and C563T were absent. Bivariate Statistical analysis showed a statistically significant association between G6PD genotypes and zoba (P < 0.004 < 0.05). Sequencing revealed the expected A376G variant. In exon 5, four common (A376G) mutations, three uncommon mutations rs782669677 (535G→A) and one potentially new mutation (451G→C), relative to the reference, mRNA NM_001042351 were detected. Bioinformatic analysis of these mutations' potential functional impact suggests minimal effect on protein function. Conclusion: this is the first report indicating that G6PD B and G6PD A genotypes are prevalent in Eritrea. Similar findings were reported in neighboring countries. Further studies including phenotype analysis are needed to corroborate the observed results.

European Journal of Medicinal Plants

Objective: To evaluate the antiplasmodial activity and safety of organic and aqueous flower extra... more Objective: To evaluate the antiplasmodial activity and safety of organic and aqueous flower extracts of Chrysanthemum cinerariaefolium from Kenya, singly and in combination with chloroquine, lumefantrine and piperaquine. Methodology: Antiplasmodial activity of organic and aqueous flower extracts of C. cinerariaefolium was assessed in vitro by serial micro-dilution assay technique against Plasmodium falciparum, and in vivo using the 4-day suppressive test as well as the established infection test against P. berghei ANKA in mice. To determine the safety of the extracts, cytotoxicity evaluation of extracts against Vero E6 cells and acute toxicity studies in mice were also done. Results: In vitro antiplasmodial assays showed that methanolic extract of C. cinerariaefolium flowers was active, petroleum ether extract was moderately active, while the aqueous extract was inactive. Methanolic extract combined with chloroquine (CQ) against CQ-sensitive (3D7) and CQresistant (W2) P. falciparum showed marked synergy. Both methanol and aqueous extracts (1000mg/kg) showed chemosuppression of >45% (P<0.05) in both 4-day suppression test and established infection test against P. berghei ANKA in mice. Lumefantrine (LU) or piperaquine (PQ) combined with either methanol or aqueous extracts showed chemosuppression of >63% (P<0.05) against LU-resistant and PQ-resistant P. berghei ANKA strains, indicating synergistic interactions. Methanolic and aqueous flower extracts of C. cinerariaefolium had no cytotoxic effect on Vero E6 cells and no overt signs of toxicity in mice. Conclusion: The findings showed that C. cinerariaefolium flower extracts are safe in mammalian systems, have antiplasmodial activity and have potentiation effect of conventional antimalarials. There is need therefore to further explore the plant's bioactive molecules which may serve as template for development of novel, effective and affordable antimalarial agents for management of malaria.

Research and Reviews of Infectious Diseases

Background: Although tea infusions of Artemisia annua L. and Artemisia apiacea have been used > 2... more Background: Although tea infusions of Artemisia annua L. and Artemisia apiacea have been used > 2000 years in traditional Chinese medicine, there was no apparent resistance development to malaria parasites. Artemisinin was isolated and characterized in 1972 as the major potent antimalarial component of A. annua. This and a number of its derivatives have been promoted in combination therapy (ACTs) with other antimalarials with different mechanisms of action. However, recent reports on artemisinin resistance have posed a major health security risk globally. The aim of the present study was to compare the effects of cyclic exposures of the malaria parasite Plasmodium falciparum to a phytochemical blend of Artemisia annua (extracted with solvents of different polarity) with those of pure artemisinin to see if the natural blend has a built-in resistance-mitigating effect on artemisinin against the parasite. Materials and methods: Upper foliage of Artemisia annua was extracted with solvents of increasing polarity, including hexane, dichloromethane, methanol, and water. The organic solvents were removed on a rotary evaporator and water by freeze-drying. In vitro cyclic exposure experiments to equivalents of IC 50 and IC 90 of (i) A. annua phytochemical blend and (ii) pure artemisinin were conducted on CQ-resistant strain cultures of P. falciparum W2 from Indochina. Dose-response effects of the parasites were determined after 10, 20, 30 and 40 cycles of exposures and relative shifts in the sensitivities of parasites (IC 50 new/IC 50 initial, or IC 90 new/IC 90 initial) expressed as relative sensitivity indices (RSI) were calculated. Results: There were incremental increases in the IC 50 or IC 90 values with increasing cycles of exposures of W2 parasites to IC 50 or IC 90 equivalents of artemisinin. No comparable increases were observed with the parasites exposed to IC 50 and IC 90 equivalents of A. annua blend. On the other hand, parasites repeatedly exposed to the A. annua blend showed decreasing susceptibility to pure artemisinin. Conclusion: The results show that ethnopharmacological mode of use of the phytochemical blend of A. annua is less likely to lead to resistance development to malaria parasites compared with pure artemisinin. This is partially consistent with a recent finding on a rodent malaria model done by Elfawal, which demonstrated that the whole A. annua plant (WP) overcomes existing resistance of Plasmodium yoelii to pure artemisinin. However, further studies are needed to elucidate the nature of observed resistance to artemisinin in the parasites that were repeatedly exposed to A. annua phytochemical blend.

Infection, Genetics and Evolution

Resistance to the mainstay antimalarial drugs is a major concern in the control of malaria. Delay... more Resistance to the mainstay antimalarial drugs is a major concern in the control of malaria. Delayed Plasmodium falciparum parasite clearance has been associated with Single Nucleotide Polymorphisms (SNPs) in the kelch propeller region (K13). However, SNPs in the Pf-adaptor protein complex 2 mu subunit (Pfap2-mu), Pfcrt and Pfmdr1 are possible markers associated with multi-drug resistance. Here, we explored the prevalence of SNPs in the K13, Pfap2-mu, Pfcrt, and Pfmdr1 in 94 dried blood spot field isolates collected from children aged below 12 years infected with P. falciparum during a cross-sectional study. The samples were collected in 2015 during the peak malaria transmission season in the Nyando region of Western Kenya before treatment with Artemether-Lumefantrine, the first-line artemisinin-based combination therapy (ACT) in Kenya. However, 47 of the 94 samples had recurrent parasitemia and were interrogated for the presence of the SNPs in K13 and Pfap2-mu. We used PCR amplification and sequencing to evaluate specific regions of K13 (codons 432-702), Pfap2-mu (codons 1-350), Pfmdr1 (codons 86, 1034-1246), and Pfcrt (codons 72-76) gene(s). The majority of parasites harbored the wild type K13 sequence. However, we found a unique non-synonymous W611S change. In silico studies on the impact of the W611S predicted structural changes in the overall topology of the K13 protein. Of the 47 samples analyzed for SNPs in the Pfap2-mu gene, 14 (29%) had S160 N/T mutation. The CVIET haplotype associated with CQ resistance in the Pfcrt yielded a 7.44% (7/94), while CVMNK haplotype was at 92.56%. Mutations in the Pfmdr1 region were detected only in three samples (3/94; 3.19%) at codon D1246Y. Our data suggest that parasites in the western part of Kenya harbor the wildtype strains. However, the detection of the unique SNP in K13 and Pfap2-mu linked with ACT delayed parasite clearance may suggest slow filtering of ACT-resistant parasites.

South African Journal of Botany

Abstract Malaria is one of the most dangerous and deadly tropical disease in Africa affecting mil... more Abstract Malaria is one of the most dangerous and deadly tropical disease in Africa affecting millions of individuals yearly. It is a major global public health problem, with an alarming spread of parasite resistance to the ACTs drugs. This situation explain the urge to discover new antimalarial compounds. Indigenous species to Africa and traditionally used for years by traditional healers, Artemisia afra is a big source for new antimalarial drugs. Aerial parts of Artemisia afra plant collected from South Africa, Kenya, Tanzania, Burundi and Senegal were each extracted with solvents of different polarity (hexane, dichloromethane, ethanol, and water), and the different extracts were then screened and compared for their antimalarial activities against two Plasmodium falciparum strains W2 (CQ resistant) and D6 (CQ sensitive); and also compared for their total phenols, flavonoids content and antioxidant activities. Phytochemical screening of the extracts revealed the presence of terpenoids, alkaloids, tannins, saponins and cardiac glycosides. Ethanolic extract of Artemisia afra collected from Burundi was found to have the highest concentration of phenols (606.9449 mg GAE/g of extract) and flavonoids (242.4745 mg Rutin/g of extract) and also exhibited the highest antioxidant activity (IC50 = 3.12 μg/mL) compare to the others. Total phenols and total flavonoids were found to correlate with the antioxidant activity. Artemisia afra collected from Burundi also showed the highest antimalarial activity compare to the other extracts, the hexane extract of A. afra from Burundi have the highest (IC50 = 0.71μ g/ml for W2 and IC50 = 3.18 μg/ml for D6); following by the ethanolic extract (IC50 = 2.66 μg/ml for W2 and 7.84 μg/ml for D6; then the dichloromethane extract (IC50 = 3.04 μg/ml for W2 and IC50 = 7.92 μg/ml for D6). Comparison of the five A. afra plants collected from South Africa, Kenya, Tanzania, Burundi and Senegal showed that the extracts from Burundi had the highest total content of phenols and flavonoids and also the highest level of antimalarial activity compared to the other plant extracts.

F1000Research

Background: Leishmaniasis is an endemic tropical disease caused by Leishmania parasites, transmit... more Background: Leishmaniasis is an endemic tropical disease caused by Leishmania parasites, transmitted mainly by phlebotomine sandflies, impacting both health and socioeconomic wellbeing. Currently there are inadequate therapeutic measures to manage the disease thus indicating the need for the development of affordable and effective therapeutic interventions from herbal plants as alternative medicine. This study investigated the in vitro antileishmanial effects of blends of crude extracts of Solanum nigrum and Plumbago capensis against Leishmania major. Methods: The promastigote parasites of Leishmania major were cultured and grown for 3 days in different concentrations of the individual extracts to determine minimum inhibitory concentrations (MIC). The in vitro antileishmanial efficacy was determined by exposing promastigotes and macrophages infected with L. major to the blends of extracts in ratios of 2000:250, 1000:500, 500:1000 and 250:2000. Finally, nitric oxide released by L. m...

F1000Research

Leishmania parasites (Kinetoplastida: Trypanosomatidae) are obligate intracellular parasites of m... more Leishmania parasites (Kinetoplastida: Trypanosomatidae) are obligate intracellular parasites of macrophages that causes visceral and cutaneous leishmaniases. Currently, there is inadequate therapeutic interventions to manage this endemic tropical disease, transmitted mainly by phlebotomine sandflies hence there is need to develop affordable and effective therapeutic measures. This study determined the in vitro efficacy of Solanum nigrum methanolic and aqueous plant extracts on Leishmania major parasites. Cytotoxic effects of the extracts were determined using vero cells and reported as percentage viability of the cells. The promastigote parasites of Leishmania major were cultured and grown for 3 days in different concentrations of extracts to determine the MIC and IC50 values. The in vitro antileishmanial efficacy was done on macrophages infected with L. major amastigote parasites and then treated with extracts in varying concentrations. The study revealed that all the test extract...

Science Journal of Public Health

Objective: To determine social-demographic and economic factors affecting adherence to treatment ... more Objective: To determine social-demographic and economic factors affecting adherence to treatment of HIV in exposed infants in Mumias region, Western Kenya. Methods: The study was a descriptive cross sectional study carried out among parents of HIV exposed infants in selected health facilities in western Kenya. Through random sampling, the study recruited three hundred and eighty four (384) parents aged between 15-66 years old. The parents who were recruited were seeking HIV testing, treatment and care for their infants. The laboratory procedure involved automated assay: Abbott Real-time HIV-1. Secondly, structured interviewer administered questionnaire was used to collect information from parentsof the affected infants. Data was analyzed using SPSS version 20. Results: 5.2% (20) of the participants tested positive while 94.8% (364) tested negative. Married participants were more likely to adhere to treatment (Odds ratio (OR) =1.062, 95%CI 0.628-1.796 P<0.05). Educated participants were more likely to attend their clinical appointments compared to the non-educated (0R=1.140, 95% C.I 0.949-1.369 P<0.05). Participants aged above 35 years old were more likely to adhere to treatment compared to those below 35 years old (OR=1.029, 95% C.I 0.985-1.074 P<0.05). Participants whose children tested negative at 6 weeks were more likely to adhere to treatment (OR=0.652, 95% C.I 0.185-2.305 P<0.05). Parentsunder the support of Community Health Workers (CHW) were more likely to adhere to treatment (OR=1.226, 95%C.I 0.419-3.581 P<0.05). Nonstigmatized mothers were more likely to adhere to treatment (OR=1.101, P<95% C.I 0.545-2.223). Conclusion: Adherence to treatment and care of HIV in exposed infants appears to be a significant challenge for HIV diagnostic and preventive services. To forestall the consequences, the stakeholders and government have to support the parents both financially and socially especially through public awareness campaigns to encourage them to adhere to treatment and care services.

Wellcome Open Research

Background: The human malaria parasite Plasmodium falciparum has evolved complex drug evasion mec... more Background: The human malaria parasite Plasmodium falciparum has evolved complex drug evasion mechanisms to all available antimalarials. To date, the combination of amodiaquine-artesunate is among the drug of choice for treatment of uncomplicated malaria. In this combination, a short acting, artesunate is partnered with long acting, amodiaquine for which resistance may emerge rapidly especially in high transmission settings. Here, we used a rodent malaria parasite Plasmodium berghei ANKA as a surrogate of P. falciparum to investigate the mechanisms of amodiaquine resistance. Methods: We used serial technique to select amodiaquine resistance by submitting the parasites to continuous amodiaquine pressure. We then employed the 4-Day Suppressive Test to monitor emergence of resistance and determine the cross-resistance profiles. Finally, we genotyped the resistant parasite by PCR amplification, sequencing and relative quantitation of mRNA transcript of targeted genes. Results: Submissio...

this is a retrospective study using stored blood culture isolates to compare the diagnostic techn... more this is a retrospective study using stored blood culture isolates to compare the diagnostic techniques in identification of bloodstream infection; the techniques under analysis are FilmArray polymerase chain reaction machine and MicroScan 40 plus machine compared with Analytical profile index which is routinely used in developing countries as a gold standard for identification of blood culture.In this study we are trying to establish which technique is suitable for diagnosis of bloodstream infection in terms of senstivity, accuracy, turn around time and cost

this is a retrospective study using stored blood culture isolates to compare the diagnostic techn... more this is a retrospective study using stored blood culture isolates to compare the diagnostic techniques in identification of bloodstream infection; the techniques under analysis are FilmArray polymerase chain reaction machine and MicroScan 40 plus machine compared with Analytical profile index which is routinely used in developing countries as a gold standard for identification of blood culture.In this study we are trying to establish which technique is suitable for diagnosis of bloodstream infection in terms of senstivity, accuracy, turn around time and cost

Promouvoir les énergies renouvelables pour satisfaire les besoins en électricité du continent Fév... more Promouvoir les énergies renouvelables pour satisfaire les besoins en électricité du continent Février 2013 Une version pdf (1,8 MB) est téléchargeable en français et en anglais à l’adresse

Certain breeds of domestic ruminants show remarkable resistance to the effects of African trypano... more Certain breeds of domestic ruminants show remarkable resistance to the effects of African trypanosomosis. Unlike susceptible animals, trypanotolerant animals control parasitemia and do not show severe anaemia or production loss. Identification of trypanotolerance genes in cattle is hampered by cost and breeding time. Marked differences between inbred strains of mice in their response to T. congolense infection can be exploited in the analysis of the genetic basis of the infection. Murine trypanotolerance QTLs have been identified on chromosome 17, 5 and 1, and designated as Tir1, 2 and 3, respectively. Tir1 and 2 have been fine mapped to a confidence interval of 1 cM. In order to find the mouse homologous region on the bovine genome, nucleotide sequence across 95 % CI of Tir2 and 3 were used in the selection of candidate genes. Homologous sequences were used in the definition of synteny relationships and subsequent identification of the shared disease response genes. The homologous ...

Rice is an important grain food crop being a staple food for a large part of the world's huma... more Rice is an important grain food crop being a staple food for a large part of the world's human population. Anendophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its lifewithout causing apparent disease. In this study, bioprospecting for bacterial rice root endophytes was explored. 66bacterial pure isolates were isolated from the 138 root samples collected from farmers’ and research fields. Theywere morphologically characterized and screened for biological activities. All isolates were gram negative rods.Two phosphates were used for phosphate solubilisation, in which case more positive response was observed incalcium phosphate than in Alluminium phosphate. Nine isolates were identified to produce IAA- indoleacetic acidimplying potential to enhance plant growth. All isolates tested negative for denitrification test. The biochemicaltests carried out helped reduce the number of isolates from 66 to 30 upon similarity and uniquenes...

Journal of Ethnopharmacology, 2016

Background:The emergence and spread of drug resistance of the malaria parasite to the main treatm... more Background:The emergence and spread of drug resistance of the malaria parasite to the main treatment emphasis the need to develop new antimalarial drugs. In this context, the fatty acid biosynthesis (FAS_II) pathway of the malaria parasite is one of the ideal target due to its crucial role in parasite survival.Method:We report in this study the expression and the affinity binding of two Fab enzymes (FabI and FabZ) after exposure of the parasite using different extracts of the Artemisia afra and after a virtual screening with the different plant compounds. Two differents strains of Plasmodium falciparum was used: W2 (CQ_resistant) and D6 (CQ_sensitive) with a parasiteamia of 4%. The parasites were exposed during 2 days to different Artemisia afra extracts . Gene expression was done to determine the level of expression of the fab enzymes after treatments. A GCMS was run to determine the different compounds of the plant extracts following by a virtual screening between the fab enzymes ...

F1000Research

Background: Bloodstream infection (BSI) contributes to a substantial proportion of mortality in s... more Background: Bloodstream infection (BSI) contributes to a substantial proportion of mortality in sub-Saharan Africa and is marked by the presence of bacterial and/or fungal microorganisms in the blood. Because BSI can be life threatening, it requires a timely, reliable and accurate diagnosis. This study retrospectively analyzed data of identified BSI pathogens and compared the performance of the different diagnostic technologies used in terms of accuracy, sensitivity, turnaround time (TAT) and cost. Methods: Currently, culture followed by analytical profile index biochemical strips (API), (BioMerieux) are used as the conventional standard diagnostics in Kenyan public hospitals and labs. We compared the results of this standard to that of the BioFire FilmArray (FA) (BioFire Diagnostics) and MicroScan WalkAway-40 plus System (MS) (Beckman Coulter) used in diagnosis of BSI. The FA technology was able to identify 150/152 bacterial and yeast isolates with an overall accuracy of 99.04% (95...

Chemistry – An Asian Journal

We demonstrated the photoredox catalytic performances of fluorescein derivatives, bearing heavy h... more We demonstrated the photoredox catalytic performances of fluorescein derivatives, bearing heavy halogen atoms (Br or I) on a benzoic acid group, using photoinitiated free-radical polymerization. 4,5,6,7-Tetrabromofluorescein and 4,5,6,7-tetraiodofluorescein were used as visible-light-photoredox catalysts to initiate polymerization of poly(ethylene glycol) diacrylate and N-vinylpyrrolidone in the presence of triethanolamine under aerobic conditions. Their photocatalytic performances were evaluated by the hydrogelation of photopolymerization both on the surface of an agarose film and in a liquid solution. The polymerization degree increased considerably in the following order: tetraiodofluorescein < tetrabromofluorescein < fluorescein. This result was different from fluorescein derivatives containing the heavy halogen atoms on a xanthene core ring. Consequently, the location of the heavy halogen atoms was crucial in the photocatalytic performance of fluorescein derivatives.

Chemistry – An Asian Journal

American Journal of Laboratory Medicine

Pre-clinical transmission assays are essential for proof-of-concept for transmission blocking str... more Pre-clinical transmission assays are essential for proof-of-concept for transmission blocking strategies but are hazardous to laboratory personnel and animal hosts as it entails exposure of live rodents to infected vectors. Conventional transmission assay methods include the use of anesthesia (associated with undesired side effects). In addition, animal handlers risk being bitten by experimental animals and vectors during anesthesia due to a lack of safe and effective alternatives. Robustness of rodent to vector transmission was determined by comparing the number of oocysts. Vector-to-rodent transmission was determined by measuring parasitemia, gametocytemia, changes in body weight and survival time. A completely randomized design was used in this study. Rodent-to-vector transmission was analyzed by log linear model. Fecundity, gametocytemia, parasitaemia and changes in body weight were analyzed by regression analysis. Survival times were analyzed Kaplan-Meier method for determination of survival distribution function. Rank test of homogeneity were used to determine the effect of restraining method infection on survival times. There was no significant difference (p<0.001) in fecundity of mosquitoes fed on anesthetized mice; 122±22.1 eggs compared to INFECTRA®-Kit group with 110±14.1 eggs. Oocyst production increased gradually though not significantly (p<0.001) in both groups of mice with the number of mosquitoes. The INFECTRA®-Kit group increased from 2.7%±0.3 (1 mosquito) to 9.3%±0.3 (6 mosquitoes), the conventional group was 3.7%±0.3 to 8.6%±0.3 (6 mosquitoes). Parasitemia progression was characterized by two waves in INFECTRA®-Kit and three waves in the conventional group. The highest parasitaemia peak was 22% attained on 22dpi for the INFECTRA®-Kit and 17.8% attained on 26 dpi for the conventional group. Gametocytes were detected on 16 dpi in both groups and thereafter increased significantly (p<0.001) with dpi. In the INFECTRA®-Kit group, gametocytemia was represented by two oscillations while the conventional group was three cycles with peak gametocytes increasing with each subsequent peak. Disease progression was higher and survival times shorter with INFECTRA ®-Kit than with anesthetized mice and there was no significant difference (p<0.05) between the two methods in body weight and gametocytemia. INFECTRA ®-Kit is equivalent to that of anesthesia method but more advantageous given the more ethical and humane treatment of animals.

Pan African Medical Journal

Introduction: glucose 6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy ... more Introduction: glucose 6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy with a relatively high frequency in malariaendemic regions. In Eritrea, there is scanty knowledge of G6PD deficiency. The aim of the study was to characterize and determine the prevalence of four common G6PD allelic variants. Methods: three hundred and fourteen dried blood spot samples from unrelated microscopically diagnosed malaria patient Eritrean ethnic groups living in five zobas (regions) of Eritrea were analysed by PCR-RFLP method to identify the G6PD B, G6PD A (A376G), G6PD A-(G202A), and G6PD Mediterranean (C563T) variants. To confirm the RFLP results, samples positive for A376G but negative for G202A variants were subjected to Sanger sequencing and a subset of PCR products (exon 5) directly sequenced to identify A376G and other mutations. Results: for G6PD genotyping, G6PD B was detected in 87.5% and A376G detected in 12.5% of malaria patients, whereas G202A and C563T were absent. Bivariate Statistical analysis showed a statistically significant association between G6PD genotypes and zoba (P < 0.004 < 0.05). Sequencing revealed the expected A376G variant. In exon 5, four common (A376G) mutations, three uncommon mutations rs782669677 (535G→A) and one potentially new mutation (451G→C), relative to the reference, mRNA NM_001042351 were detected. Bioinformatic analysis of these mutations' potential functional impact suggests minimal effect on protein function. Conclusion: this is the first report indicating that G6PD B and G6PD A genotypes are prevalent in Eritrea. Similar findings were reported in neighboring countries. Further studies including phenotype analysis are needed to corroborate the observed results.

European Journal of Medicinal Plants

Objective: To evaluate the antiplasmodial activity and safety of organic and aqueous flower extra... more Objective: To evaluate the antiplasmodial activity and safety of organic and aqueous flower extracts of Chrysanthemum cinerariaefolium from Kenya, singly and in combination with chloroquine, lumefantrine and piperaquine. Methodology: Antiplasmodial activity of organic and aqueous flower extracts of C. cinerariaefolium was assessed in vitro by serial micro-dilution assay technique against Plasmodium falciparum, and in vivo using the 4-day suppressive test as well as the established infection test against P. berghei ANKA in mice. To determine the safety of the extracts, cytotoxicity evaluation of extracts against Vero E6 cells and acute toxicity studies in mice were also done. Results: In vitro antiplasmodial assays showed that methanolic extract of C. cinerariaefolium flowers was active, petroleum ether extract was moderately active, while the aqueous extract was inactive. Methanolic extract combined with chloroquine (CQ) against CQ-sensitive (3D7) and CQresistant (W2) P. falciparum showed marked synergy. Both methanol and aqueous extracts (1000mg/kg) showed chemosuppression of >45% (P<0.05) in both 4-day suppression test and established infection test against P. berghei ANKA in mice. Lumefantrine (LU) or piperaquine (PQ) combined with either methanol or aqueous extracts showed chemosuppression of >63% (P<0.05) against LU-resistant and PQ-resistant P. berghei ANKA strains, indicating synergistic interactions. Methanolic and aqueous flower extracts of C. cinerariaefolium had no cytotoxic effect on Vero E6 cells and no overt signs of toxicity in mice. Conclusion: The findings showed that C. cinerariaefolium flower extracts are safe in mammalian systems, have antiplasmodial activity and have potentiation effect of conventional antimalarials. There is need therefore to further explore the plant's bioactive molecules which may serve as template for development of novel, effective and affordable antimalarial agents for management of malaria.

Research and Reviews of Infectious Diseases

Background: Although tea infusions of Artemisia annua L. and Artemisia apiacea have been used > 2... more Background: Although tea infusions of Artemisia annua L. and Artemisia apiacea have been used > 2000 years in traditional Chinese medicine, there was no apparent resistance development to malaria parasites. Artemisinin was isolated and characterized in 1972 as the major potent antimalarial component of A. annua. This and a number of its derivatives have been promoted in combination therapy (ACTs) with other antimalarials with different mechanisms of action. However, recent reports on artemisinin resistance have posed a major health security risk globally. The aim of the present study was to compare the effects of cyclic exposures of the malaria parasite Plasmodium falciparum to a phytochemical blend of Artemisia annua (extracted with solvents of different polarity) with those of pure artemisinin to see if the natural blend has a built-in resistance-mitigating effect on artemisinin against the parasite. Materials and methods: Upper foliage of Artemisia annua was extracted with solvents of increasing polarity, including hexane, dichloromethane, methanol, and water. The organic solvents were removed on a rotary evaporator and water by freeze-drying. In vitro cyclic exposure experiments to equivalents of IC 50 and IC 90 of (i) A. annua phytochemical blend and (ii) pure artemisinin were conducted on CQ-resistant strain cultures of P. falciparum W2 from Indochina. Dose-response effects of the parasites were determined after 10, 20, 30 and 40 cycles of exposures and relative shifts in the sensitivities of parasites (IC 50 new/IC 50 initial, or IC 90 new/IC 90 initial) expressed as relative sensitivity indices (RSI) were calculated. Results: There were incremental increases in the IC 50 or IC 90 values with increasing cycles of exposures of W2 parasites to IC 50 or IC 90 equivalents of artemisinin. No comparable increases were observed with the parasites exposed to IC 50 and IC 90 equivalents of A. annua blend. On the other hand, parasites repeatedly exposed to the A. annua blend showed decreasing susceptibility to pure artemisinin. Conclusion: The results show that ethnopharmacological mode of use of the phytochemical blend of A. annua is less likely to lead to resistance development to malaria parasites compared with pure artemisinin. This is partially consistent with a recent finding on a rodent malaria model done by Elfawal, which demonstrated that the whole A. annua plant (WP) overcomes existing resistance of Plasmodium yoelii to pure artemisinin. However, further studies are needed to elucidate the nature of observed resistance to artemisinin in the parasites that were repeatedly exposed to A. annua phytochemical blend.

Infection, Genetics and Evolution

Resistance to the mainstay antimalarial drugs is a major concern in the control of malaria. Delay... more Resistance to the mainstay antimalarial drugs is a major concern in the control of malaria. Delayed Plasmodium falciparum parasite clearance has been associated with Single Nucleotide Polymorphisms (SNPs) in the kelch propeller region (K13). However, SNPs in the Pf-adaptor protein complex 2 mu subunit (Pfap2-mu), Pfcrt and Pfmdr1 are possible markers associated with multi-drug resistance. Here, we explored the prevalence of SNPs in the K13, Pfap2-mu, Pfcrt, and Pfmdr1 in 94 dried blood spot field isolates collected from children aged below 12 years infected with P. falciparum during a cross-sectional study. The samples were collected in 2015 during the peak malaria transmission season in the Nyando region of Western Kenya before treatment with Artemether-Lumefantrine, the first-line artemisinin-based combination therapy (ACT) in Kenya. However, 47 of the 94 samples had recurrent parasitemia and were interrogated for the presence of the SNPs in K13 and Pfap2-mu. We used PCR amplification and sequencing to evaluate specific regions of K13 (codons 432-702), Pfap2-mu (codons 1-350), Pfmdr1 (codons 86, 1034-1246), and Pfcrt (codons 72-76) gene(s). The majority of parasites harbored the wild type K13 sequence. However, we found a unique non-synonymous W611S change. In silico studies on the impact of the W611S predicted structural changes in the overall topology of the K13 protein. Of the 47 samples analyzed for SNPs in the Pfap2-mu gene, 14 (29%) had S160 N/T mutation. The CVIET haplotype associated with CQ resistance in the Pfcrt yielded a 7.44% (7/94), while CVMNK haplotype was at 92.56%. Mutations in the Pfmdr1 region were detected only in three samples (3/94; 3.19%) at codon D1246Y. Our data suggest that parasites in the western part of Kenya harbor the wildtype strains. However, the detection of the unique SNP in K13 and Pfap2-mu linked with ACT delayed parasite clearance may suggest slow filtering of ACT-resistant parasites.

South African Journal of Botany

Abstract Malaria is one of the most dangerous and deadly tropical disease in Africa affecting mil... more Abstract Malaria is one of the most dangerous and deadly tropical disease in Africa affecting millions of individuals yearly. It is a major global public health problem, with an alarming spread of parasite resistance to the ACTs drugs. This situation explain the urge to discover new antimalarial compounds. Indigenous species to Africa and traditionally used for years by traditional healers, Artemisia afra is a big source for new antimalarial drugs. Aerial parts of Artemisia afra plant collected from South Africa, Kenya, Tanzania, Burundi and Senegal were each extracted with solvents of different polarity (hexane, dichloromethane, ethanol, and water), and the different extracts were then screened and compared for their antimalarial activities against two Plasmodium falciparum strains W2 (CQ resistant) and D6 (CQ sensitive); and also compared for their total phenols, flavonoids content and antioxidant activities. Phytochemical screening of the extracts revealed the presence of terpenoids, alkaloids, tannins, saponins and cardiac glycosides. Ethanolic extract of Artemisia afra collected from Burundi was found to have the highest concentration of phenols (606.9449 mg GAE/g of extract) and flavonoids (242.4745 mg Rutin/g of extract) and also exhibited the highest antioxidant activity (IC50 = 3.12 μg/mL) compare to the others. Total phenols and total flavonoids were found to correlate with the antioxidant activity. Artemisia afra collected from Burundi also showed the highest antimalarial activity compare to the other extracts, the hexane extract of A. afra from Burundi have the highest (IC50 = 0.71μ g/ml for W2 and IC50 = 3.18 μg/ml for D6); following by the ethanolic extract (IC50 = 2.66 μg/ml for W2 and 7.84 μg/ml for D6; then the dichloromethane extract (IC50 = 3.04 μg/ml for W2 and IC50 = 7.92 μg/ml for D6). Comparison of the five A. afra plants collected from South Africa, Kenya, Tanzania, Burundi and Senegal showed that the extracts from Burundi had the highest total content of phenols and flavonoids and also the highest level of antimalarial activity compared to the other plant extracts.

F1000Research

Background: Leishmaniasis is an endemic tropical disease caused by Leishmania parasites, transmit... more Background: Leishmaniasis is an endemic tropical disease caused by Leishmania parasites, transmitted mainly by phlebotomine sandflies, impacting both health and socioeconomic wellbeing. Currently there are inadequate therapeutic measures to manage the disease thus indicating the need for the development of affordable and effective therapeutic interventions from herbal plants as alternative medicine. This study investigated the in vitro antileishmanial effects of blends of crude extracts of Solanum nigrum and Plumbago capensis against Leishmania major. Methods: The promastigote parasites of Leishmania major were cultured and grown for 3 days in different concentrations of the individual extracts to determine minimum inhibitory concentrations (MIC). The in vitro antileishmanial efficacy was determined by exposing promastigotes and macrophages infected with L. major to the blends of extracts in ratios of 2000:250, 1000:500, 500:1000 and 250:2000. Finally, nitric oxide released by L. m...

F1000Research

Leishmania parasites (Kinetoplastida: Trypanosomatidae) are obligate intracellular parasites of m... more Leishmania parasites (Kinetoplastida: Trypanosomatidae) are obligate intracellular parasites of macrophages that causes visceral and cutaneous leishmaniases. Currently, there is inadequate therapeutic interventions to manage this endemic tropical disease, transmitted mainly by phlebotomine sandflies hence there is need to develop affordable and effective therapeutic measures. This study determined the in vitro efficacy of Solanum nigrum methanolic and aqueous plant extracts on Leishmania major parasites. Cytotoxic effects of the extracts were determined using vero cells and reported as percentage viability of the cells. The promastigote parasites of Leishmania major were cultured and grown for 3 days in different concentrations of extracts to determine the MIC and IC50 values. The in vitro antileishmanial efficacy was done on macrophages infected with L. major amastigote parasites and then treated with extracts in varying concentrations. The study revealed that all the test extract...

Science Journal of Public Health

Objective: To determine social-demographic and economic factors affecting adherence to treatment ... more Objective: To determine social-demographic and economic factors affecting adherence to treatment of HIV in exposed infants in Mumias region, Western Kenya. Methods: The study was a descriptive cross sectional study carried out among parents of HIV exposed infants in selected health facilities in western Kenya. Through random sampling, the study recruited three hundred and eighty four (384) parents aged between 15-66 years old. The parents who were recruited were seeking HIV testing, treatment and care for their infants. The laboratory procedure involved automated assay: Abbott Real-time HIV-1. Secondly, structured interviewer administered questionnaire was used to collect information from parentsof the affected infants. Data was analyzed using SPSS version 20. Results: 5.2% (20) of the participants tested positive while 94.8% (364) tested negative. Married participants were more likely to adhere to treatment (Odds ratio (OR) =1.062, 95%CI 0.628-1.796 P<0.05). Educated participants were more likely to attend their clinical appointments compared to the non-educated (0R=1.140, 95% C.I 0.949-1.369 P<0.05). Participants aged above 35 years old were more likely to adhere to treatment compared to those below 35 years old (OR=1.029, 95% C.I 0.985-1.074 P<0.05). Participants whose children tested negative at 6 weeks were more likely to adhere to treatment (OR=0.652, 95% C.I 0.185-2.305 P<0.05). Parentsunder the support of Community Health Workers (CHW) were more likely to adhere to treatment (OR=1.226, 95%C.I 0.419-3.581 P<0.05). Nonstigmatized mothers were more likely to adhere to treatment (OR=1.101, P<95% C.I 0.545-2.223). Conclusion: Adherence to treatment and care of HIV in exposed infants appears to be a significant challenge for HIV diagnostic and preventive services. To forestall the consequences, the stakeholders and government have to support the parents both financially and socially especially through public awareness campaigns to encourage them to adhere to treatment and care services.

Wellcome Open Research

Background: The human malaria parasite Plasmodium falciparum has evolved complex drug evasion mec... more Background: The human malaria parasite Plasmodium falciparum has evolved complex drug evasion mechanisms to all available antimalarials. To date, the combination of amodiaquine-artesunate is among the drug of choice for treatment of uncomplicated malaria. In this combination, a short acting, artesunate is partnered with long acting, amodiaquine for which resistance may emerge rapidly especially in high transmission settings. Here, we used a rodent malaria parasite Plasmodium berghei ANKA as a surrogate of P. falciparum to investigate the mechanisms of amodiaquine resistance. Methods: We used serial technique to select amodiaquine resistance by submitting the parasites to continuous amodiaquine pressure. We then employed the 4-Day Suppressive Test to monitor emergence of resistance and determine the cross-resistance profiles. Finally, we genotyped the resistant parasite by PCR amplification, sequencing and relative quantitation of mRNA transcript of targeted genes. Results: Submissio...