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Dr. N N

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Research Focus & Metrics

Academic Career Length

11Years (2016-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 July 2016 in Malaria Journal
Verified
Journal Article
Open access
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NNN N
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JKJoseph N. Kang’ethe
Joseph N. Kang’ethe
JKJohnson Kinyua
Johnson Kinyua
DKDaniel Kariuki
Daniel Kariuki
FKFrancis T. Kimani
Francis T. Kimani
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 bidirectional sequencing and reading the transcripts against wild-type sequences in Codon code Aligner Version 5.1 and NCBI blast. Exposure of parasite strains D6 and W2 to artemisinin resulted in a decrease in parasite susceptibility to artemisinin (W2 and D6) and lumefantrine (D6 only). The parasites exhibited elevated IC50s to multiple artemisinins, with >twofold resistance to artemisinin; however, the resistance index obtained with standard methods was noticeably less than expected for parasite lines recovered from 50 µg/ml 48 h drug pressure. The change in parasite susceptibility was associated with Pfmdr-185K mutation, a mutation never reported before. The Pfcrt-CVMNK genotype (Pfcrt codons 72–76) was retained and notably, the study did not detect any polymorphisms reported to reduce P. falciparum susceptibility in vivo in the coding sequences of the Pfk13 gene. This data demonstrate that P. falciparum has the capacity to develop resistance to artemisinin derivatives in vitro and that this phenotype is achieved by mutations in Pfmdr1, the genetic changes that are also underpinning lumefantrine resistance. This finding is of practical importance, because artemisinin drugs in Kenya are used in combination with lumefantrine for the treatment of malaria. Artemisinin resistance phenotype as has been shown in this work, is a decrease in parasites susceptibility to artemisinin derivatives together with the parasite’s ability to recover from drug-induced dormancy after exposure to drug dosage above the in vivo clinical concentrations. The study surmises that Pfmdr1 may play a role in the anti-malarial activity of artemisinin.

7 May 2023 in Diagnostics
Verified
Journal Article
Open access
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KSKate Obaayaa Sagoe
Kate Obaayaa Sagoe
MKMutinda Mutinda Kyama
Mutinda Mutinda Kyama
NMNaomi Maina
Naomi Maina
MKMoses Kamita
Moses Kamita
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JGJesse Gitaka
Jesse Gitaka
Globally, the emergence of the coronavirus disease (COVID-19) has had a significant impact on life. The need for ongoing SARS-CoV-2 screening employing inexpensive and quick diagnostic approaches is undeniable, given the ongoing pandemic and variations in vaccine administration in resource-constrained regions. This study presents results as proof of concept to use hybridization chain reaction (HCR) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a complex for detecting SARS-CoV-2. HCR hairpin probes were designed using the NUPACK web-based program and further used to amplify the SARS-CoV-2 N gene in archived nasopharyngeal samples. The results were visualized using agarose gels and CRISPR Cas12a-based lateral flow strips. The assay was evaluated using the gold standard, real-time polymerase chain reaction (RT-PCR), as recommended by the World Health Organization (WHO). The results show the comparative efficiency of HCR to RT-PCR. This study shows that HCR and CRISPR are viable alternatives for diagnosing SARS-CoV-2 in samples.

31 August 2020 in Journal of Medicinal Plants Research
Verified
Journal Article
Open access
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KJK. Ng’eTich Japheth
K. Ng’eTich Japheth
SHS. Swai Hulda
S. Swai Hulda
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WSW. Wachira Sabina
W. Wachira Sabina
CLC. Koech Lilian
C. Koech Lilian
WJW. Gathirwa Jeremiah
W. Gathirwa Jeremiah
Despite past decades of steady advances in the fight against Malaria, statistics show that the disease is still a threat to human health. Previous successes in the development of antimalarial drugs from medicinal plants have fuelled research in this area. However, antimalarial studies on fractionated extracts from such plants have progressed slowly. This study reports the antimalarial potential of fractions from Lippia kituiensis Vatke, for the first time. Column chromatography was used during fractionation. Antiplasmodial assay against chloroquine-sensitive (D6) and resistant (W2) plasmodium strains were done using hypoxanthine incorporation assay. MTT assay was used to assess the cytotoxicity of fractions against the Vero cell line. Fractions obtained exhibited varied inhibitory concentrations (IC50); with the most efficacious being, Lk-5 (19.45 ± 6.20 μg/ml), Lk-3 (30.43 ± 0.68 μg/ml), Lk-4 (30.82 ± 18.01 μg/ml), and Lk-6 (36.53 ± 14.42 μg/ml) against D6. Generally, lower activity against W2 was obtained with the most active being LK-4 (24.18±2.50 μg/ml), and Lk-5 (24.42±5.95 μg/ml), while chloroquine (positive control) exerted IC50 of 77.86±4.09 ng/ml (W2) and 15.71±6.49 ng/ml (D6). LK-4 was the most cytotoxic showing cytotoxic concentration (CC50), 46.26 μg/ml. When tested in mice, fractions suppressed Plasmodium berghei significantly compared to the negative control with Lk-3 being most efficacious (80.01±1). Due to substantive efficacy, GC-MS done on Lk-3 revealed 8 compounds where three have previously been ascribed to antimalarial activity and other pharmacological effects. This study adds to present knowledge of antimalarial efficacy of L. kituiensis and provides the basis for further work to be done on the isolation of compounds from its extracts. Key words: Malaria, chromatography, alkaloids, cytotoxicity, phytochemistry.

1 January 2020 in Forensic Science International: Synergy
Verified
Journal Article
Open access
ENEva Aluvaala Nambati
Eva Aluvaala Nambati
NNN N
N N
FEFred Eyase
Fred Eyase
JMJanet Majanja
Janet Majanja
NNNaomi Njuguna
Naomi Njuguna
WBWallace Bulimo
Wallace Bulimo
The uptake of forensic DNA testing technologies in Africa has been slow despite the revolutionary technology being discovered and adopted 3 decades ago. African governments and partners have invested in construction and equipping of forensic laboratories in Africa but the benefits are yet to be realised as the laboratories are still faced with the challenge of shortage of adequately trained personnel. This paper describes an innovative multidisciplinary training approach that was developed and used to train officers from the Directorate of Criminal Investigations Kenya. We report on the structure, implementation and effectiveness of the training. It is expected that with the increased number of trained forensic DNA analysts, there will be an improvement in quality of forensic DNA evidence presented in courts and a reduction in backlog in the forensic biology laboratories in Kenya.

1 January 2024 in Medical Research Archives
Verified
Journal Article
Open access
PDF file
NNN N
N N
DKDivya Kamath
Divya Kamath
SBStefan H. Bossmann
Stefan H. Bossmann
Targeted protein degradation is an emerging approach for novel drug discovery and basic research. Several degrader molecules have been developed including PROteolysis-TArgeting Chimeras (PROTACs), specific and nongenetic Inhibitor of APoptosis protein (IAP)-dependent Protein ERasers (SNIPERs), IAP antagonists, deubiquitylase inhibitors, hydrophobic tagging molecules, and E3 modulators. The chimeric degrader molecules PROTACs and SNIPERs are made of linking a target protein-ligand to an E3 ubiquitin ligase binding ligand. This modular nature of these chimeric molecules supports versatile protein targets by substituting target ligands. They induce ubiquitylation and proteasomal degradation of the target protein in the cytosol via recruiting an E3 ubiquitin ligase to the target protein. The bridging of the target protein and the E3 ubiquitin ligase facilitates ubiquitylation of the protein and its proteasomal degradation. PROTACs chimeric molecules recruit von Hippel–Lindau or cereblon ubiquitin ligases, while SNIPERs induce simultaneous degradation of cIAP1/2 or XIAP together with the target proteins. Several B-cell Lymphoma 2 (BCL-2) family anti-apoptosis proteins BCL-2, BCL-XL, and MCL-1 are validated anticancer targets and are upregulated in various malignancies. Also, aberrant expression of cIAP1/2 and XIAP with a concomitant increase in apoptosis resistance has been reported. The dysregulation of BCL2 and IAP gene expression in cancer disease is mainly caused by upregulation of the bromodomain and extra-terminal domain (BET) proteins. Degradation of the cellular anti-apoptosis proteins mentioned is a promising approach to induce apoptosis in tumor cells and overcome treatment resistance. Various types of protein degradation strategies have been developed and used. This article overviewed various chimeric compounds capable of inducing the degradation of anti-apoptosis proteins BCL2, BET, and IAP in cancer treatment.