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Papers by daniel kariuki

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

www.mdpi.com/journal/pathogens

Despite advancement in malaria research, it continues to be a global problem. Of the estimated ... more Despite advancement in malaria research, it continues to be a global problem. Of the estimated 655,000 malaria deaths occurring 2011, about 90% occurred in Africa and mainly in children under the age of 5 years. The current WHO first-line treatment for malaria is the artemisinin based combination therapies (ACTs). With increased reports of reduced susceptibility of Plasmodium falciparum to ACTs, the search for new drugs is vital. The aim of this study was to screen Plasmodium falciparum genome for possible drug targets and model novel drug compounds by use of bioinformatics approaches. Plasmodium falciparum genome sequence data was downloaded and screened using GenScanTMfor potential drug targets. Target sequences were validated using sequence motif database ScanProsite for identification of specific residues likely to be involved infunction. The uniqueness of the target proteins was underpinned by use of homology searchalgorithms specifically BLASTp. Some of the target prote...

Tea is one of the most popular beverages worldwide, native to Southeast Asia but currently cultiv... more Tea is one of the most popular beverages worldwide, native to Southeast Asia but currently cultivated in over 35countries. Studies on its chemical composition reveal that polyphenol metabolites account for 25% to 35% of thetotal dry weight. Tea has many health benefits owing to secondary metabolites whose level of expression invarious tea clones determine tea flavor. The flavor (taste and aroma) and the color of processed tea are used toassess its quality and therefore a detailed analysis of key enzymes involved in the synthesis of secondarymetabolites is necessary. This study employed a computational approach in the analysis of these enzymes to gaininsight into the mechanism of synthesis of these bioactive secondary metabolites. Biological databases were usedto retrieve amino acid sequences of these key enzymes. Consensus conserved regions in these sequences wereidentified from highly identical homologs which were useful in modeling the enzymes' three dimensionalstructures. A t...

African Journal of Agricultural Research, 2013

A survey was conducted to determine the diversity and distribution of soil nematodes associated w... more A survey was conducted to determine the diversity and distribution of soil nematodes associated with tea in Ngere tea catchment area in Kenya. Soil samples were collected from six electoral zones of Ngere factory in Gatanga division Thika district, Murang’a County, Kenya. Nematodes were extracted and recovered from soil samples using a modified Baermann funnel method and identified under a light microscope based on their morphological characters. They were also classified according to their feeding habits. Ten genera belonging to, bacteriovores, fungivores, and omnivores were identified. Fungal feeding and parasitic nematodes were the most widely distributed trophic groups across the tea catchment area. Plant-parasitic nematodes recovered included Pratylenchus spp., Helicotylenchus spp., Rotylenchus spp., Aphelenchus spp., Rotylenchulus spp., and Xiphinema spp. Tylenchus spp was the most frequently occurring species in the soil (60.47%) where the population was 429 followed by Praty...

Journal of Agricultural Science and Technology, 2016

The Kenyan green ,orthodox, and black tea ( Camellia sinensis ) aqueous extracts were subjected... more The Kenyan green ,orthodox, and black tea ( Camellia sinensis ) aqueous extracts were subjected to reagent based chemical screening of bioactive constituents, and their in vivo anti -Plasmodium berghei ANKA effects on parasitemia, % pcv and serum proteins concentration done using a 105 male swiss mice model to determine their pharmacological significance. The phytochemical results from the colorimetric tests of green, orthodox and black teas showed the presence of alkaloids, flavonoids, saponins, terpenes and tannins as common metabolites. Anthraquinones were not detected in green tea unlike orthodox and black teas. There was significant reduction (p < 0.05) in parastemia levels of p=2.6 on day 10 after infection compared to the control. The fall in packed cell volume (pcv) occurred on day 7 after infection of p=4.17. There was a significant difference in pcv levels p=4.8 (p < 0.05) on day 11 between the infected mice given tea and the infected control. There was a...

Despite the importance of helmeted Guinea fowls, little is known about their origin and genetic b... more Despite the importance of helmeted Guinea fowls, little is known about their origin and genetic background. This study aimed to understand t he genet ic background of helmeted Guinea fowls in Kenya through the characterizat ion of t heir morphological t rait s, analysis of the mitochondrial DNA D - loop and identification of polymorphisms in the HSP70 gene associated with drought/heat tolerance. Ninety (90) Guinea fowls randomly selected from four domestic populations (70 individuals) and a wild population (20 individuals) sampled from Bungoma, Busia and Laikipia counties in Kenya were scored for primary phenotypic characteristics (shank length, body length, wing length, helmet width, helmet height, head size, live body weight, wattle colour, skin colour and shank colour). DNA was also extracted from blood collected from the 90 individuals. The phenotypic data collected were analyzed and the descriptive statistics obtained com...

F1000Research, 2020

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...

F1000Research, 2018

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...

Malaria journal, Jul 22, 2016

Anti-malarial drugs are the major focus in the prevention and treatment of malaria. Artemisinin-b... more Anti-malarial drugs are the major focus in the prevention and treatment of malaria. Artemisinin-based combination therapy (ACT) is the WHO recommended first-line treatment for Plasmodium falciparum malaria across the endemic world. Also ACT is increasingly relied upon in treating Plasmodium vivax malaria where chloroquine is failing. The emergence of artemisinin drug-resistant parasites is a serious threat faced by global malaria control programmes. Therefore, the success of treatment and intervention strategies is highly pegged on understanding the genetic basis of resistance. Here, resistance in P. falciparum was generated in vitro for artemisinin to produce levels above clinically relevant concentrations in vivo, and the molecular haplotypes investigated. Genomic DNA was extracted using the QIAamp mini DNA kit. DNA sequences of Pfk13, Pfcrt and Pfmdr1 genes were amplified by PCR and the amplicons were successfully sequenced. Single nucleotide polymorphisms were traced by standard...

Schistosomiasis is a parasitic disease that leads to chronic ill-health. Infection is acquired fr... more Schistosomiasis is a parasitic disease that leads to chronic ill-health. Infection is acquired from infested freshwater containing the larval forms (cercariae) of blood flukes, known as schistosomes. The three main species of the parasite that infect humans are Schistosoma haematobium, S.japonicum, and S.mansoni. Schistosomiasis affects at least 230 million people worldwide. The infection is prevalent in tropical and subtropical areas, in poor communities without potable water and adequate sanitation. The disease is considered as one of the Neglected Tropical Diseases and so far praziquantel is the only drug used for treatment. Should the parasites develop resistance to praziquantel, treatment would be problematic. This study incorporated a computational approach to design novel compounds with unprecedented potential as candidate drug compounds for the disease. The Schistosoma mansoni fatty acid binding protein was selected as a suitable drug target for its crucial role in the depen...

American Journal of Plant Sciences, 2014

The tea plant absorbs dissolved nutrients from soils for its normal growth and development, thoug... more The tea plant absorbs dissolved nutrients from soils for its normal growth and development, though to different extents. Nutrients play vital roles in various metabolic processes, their deficiency or excess being deleterious to living organisms. A study was carried out to quantitatively assess the inorganic nutrient content (K, P, Ca, Mn, Fe, Zn and Cu) of twelve black tea samples sourced from Murang'a, Meru and Kisii tea growing agro-ecological areas in Kenya. K and P were quantified using a flame photometer and a UV-Vis spectrophotometer respectively whereas Ca, Mn, Fe, Zn and Cu were quantified using an Atomic Absorption Spectrophotometer (AAS). The general accumulation pattern of the inorganic nutrients in the tea samples was established to be; K (1.6% ± 0.05%-2.1% ± 0.01%) > P (0.30% ± 0.01%-0.37% ± 0.04%) > Ca (0.16% ± 0.01%-0.62% ± 0.03%) > Mn (0.07% ± 0.009%-0.13% ± 0.004%) > Fe (136 ± 8-320 ± 5 µg/g) > Zn (27 ± 1-39 ± 7 µg/g) > Cu (10 ± 3-16 ± 1 µg/g). Statistically significant differences (p < 0.05) were observed in the inorganic nutrient contents of the black tea from the different tea factories as well as agro-ecological areas. These data demonstrate the tea plant's ability to accumulate the studied nutrients, further underlining tea consumption as a potential dietary source of the nutritionally essential inorganic nutrients.

BioMed Research International, 2018

We analyzed variations in 90 mitochondrial DNA (mtDNA) D-loop and heat shock protein 70 (HSP70) g... more We analyzed variations in 90 mitochondrial DNA (mtDNA) D-loop and heat shock protein 70 (HSP70) gene sequences from four populations of domesticated helmeted Guinea fowls (70 individuals) and 1 population of wild helmeted Guinea fowls (20 individuals) in Kenya in order to get information about their origin, genetic diversity, and traits associated with heat stress. 90 sequences were assigned to 25 distinct mtDNA and 4 HSP70 haplotypes. Most mtDNA haplotypes of the domesticated helmeted Guinea fowls were grouped into two main haplogroups, HgA and HgB. The wild population grouped into distinct mtDNA haplogroups. Two mtDNA haplotypes dominated across all populations of domesticated helmeted Guinea fowls: Hap2 and Hap4, while the dominant HSP70 haplotype found in all populations was CGC. Higher haplotype diversities were generally observed. The HSP70 haplotype diversities were low across all populations. The nucleotide diversity values for both mtDNA and HSP70 were generally low. Most m...

International Journal of Leadership and Governance

Purpose: The study aimed to assess the effect of entrepreneurial leadership on innovation by 1-3 ... more Purpose: The study aimed to assess the effect of entrepreneurial leadership on innovation by 1-3 star rated hotels in Kenya. Methodology: This study considered positivism philosophy, quantitative measurement paradigm. The study targeted 111 hotels (1-3 star rated) through census, of which 3 respondents per hotel (CEO, Finance manager and Operations manager) were considered, from the hotels’ list provided by the Kenya Tourism Regulatory Authority (TRA). A cross sectional survey was conducted where the self-administered questionnaire was used. Both the reliability and validity tests were done before the data analysis. The collected data was analyzed using descriptive and inferential statistics with the help of Excel and SPSS version 25.0. The hypotheses were presented and tested using multiple analysis and accepted at 95 percent confidence level. Results: The findings revealed that entrepreneurial leadership and hotel innovation are positively and statistically related (β=0.669, p=0.0...

Notes: Center Discussion Papers are preliminary materials circulated to stimulate discussions and... more Notes: Center Discussion Papers are preliminary materials circulated to stimulate discussions and critical comments. MIT Sloan,

Diversity and distribution of soil nematodes in Ngere tea catchment area of Murang’a county, Kenya