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Search Results: 1 - 10 of 325181 matches for " S Songok "
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Genetic diversity in pigeonpea [Cajanus cajan (L.) Millsp.] Landraces as revealed by simple sequence repeat markers
S Songok, M Ferguson, AW Muigai, S Silim
African Journal of Biotechnology , 2010,
Abstract: Genetic relationships among 88 pigeonpea accessions from a presumed centre of origin and diversity, India and a presumed secondary centre of diversity in East Africa were evaluated using six microsatellite markers. Forty-seven (47) alleles were detected in the populations studied, with a mean of eight alleles per locus. Populations were defined by region (India and East Africa) and sub-populations by country in the case of East Africa and State in the case of India. Substantial differentiation among regions was evident from Roger’s modified distance and Wright’s F statistic. Greatest genetic diversity in terms of number of alleles, number of rare alleles and Nei’s unbiased estimate of gene diversity (H) was found in India as opposed to East Africa. This supports the hypothesis that India is the centre of diversity and East Africa is a secondary centre of diversity. Within East Africa, germplasm from Tanzania had the highest diversity according to Nei’s unbiased estimate of gene diversity, followed by Kenya and Uganda. Germplasm from Kenya and Tanzania were more closely related than that of Uganda according to Roger’s modified distance. Within India, results did not indicate a clear centre of diversity. Values of genetic distance indicated that genetic relationships followed geographical proximity.
Survey on prevalence and risk factors on HIV-1 among pregnant women in North-Rift, Kenya: a hospital based cross-sectional study conducted between 2005 and 2006
Michael Kiptoo, Solomon Mpoke, Zipporah Ng'ang'a, Jones Mueke, Fredrick Okoth, Elijah Songok
BMC International Health and Human Rights , 2009, DOI: 10.1186/1472-698x-9-10
Abstract: Blood samples were collected from pregnant women attending antenatal clinics in three district hospitals (Kitale, Kapsabet and Nandi Hills) after informed consent and pre-test counseling. The samples were tested for HIV antibodies as per the guidelines laid down by Ministry of Health, Kenya. A structured pretested questionnaire was used to obtain demographic data. Lymphocyte subset counts were quantified by standard flow cytometry.Of the 4638 pregnant women tested, 309 (6.7%) were HIV seropositive. The majority (85.1%) of the antenatal attendees did not know their HIV status prior to visiting the clinic for antenatal care. The highest proportion of HIV infected women was in the age group 21–25 years (35.5%). The 31–35 age group had the highest (8.5%) HIV prevalence, while women aged more than 35 years had the lowest (2.5%).Women in a polygamous relationship were significantly more likely to be HIV infected as compared to those in a monogamous relationship (p = 0.000). The highest HIV prevalence (6.3%) was recorded among antenatal attendees who had attended secondary schools followed by those with primary and tertiary level of education (6% and 5% respectively). However, there was no significant relationship between HIV seropositivity and the level of education (p = 0.653 and p = 0.469 for secondary and tertiary respectively). The mean CD4 count was 466 cells/mm3 (9–2000 cells/mm3). Those that had less than 200 cells/mm3 accounted for 14% and only nine were on antiretroviral therapy.Seroprevalence of HIV was found to be consistent with the reports from the national HIV sentinel surveys. Enumeration of T-lymphocyte (CD4/8) should be carried out routinely in the antenatal clinics for proper timing of initiation of antiretroviral therapy among HIV infected pregnant women.HIV/AIDS is the major health priority in Kenya. Sentinel surveillance in antenatal women has been used to project national HIV seroprevalence in Kenya since 1990 [1]. The system operates within antenata
Evaluation of HIV ELISA diagnostic kit developed at the Institute of Primate Research, Nairobi Kenya
Elephas Munene, Elijah Songok, John A Nyamongo, Daudi K Langat, Moses Otsyula
African Journal of Health Sciences , 2002,
Genetic Diversity and Demographic History of Cajanus spp. Illustrated from Genome-Wide SNPs
Rachit K. Saxena, Eric von Wettberg, Hari D. Upadhyaya, Vanessa Sanchez, Serah Songok, Kulbhushan Saxena, Paul Kimurto, Rajeev K. Varshney
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0088568
Abstract: Understanding genetic structure of Cajanus spp. is essential for achieving genetic improvement by quantitative trait loci (QTL) mapping or association studies and use of selected markers through genomic assisted breeding and genomic selection. After developing a comprehensive set of 1,616 single nucleotide polymorphism (SNPs) and their conversion into cost effective KASPar assays for pigeonpea (Cajanus cajan), we studied levels of genetic variability both within and between diverse set of Cajanus lines including 56 breeding lines, 21 landraces and 107 accessions from 18 wild species. These results revealed a high frequency of polymorphic SNPs and relatively high level of cross-species transferability. Indeed, 75.8% of successful SNP assays revealed polymorphism, and more than 95% of these assays could be successfully transferred to related wild species. To show regional patterns of variation, we used STRUCTURE and Analysis of Molecular Variance (AMOVA) to partition variance among hierarchical sets of landraces and wild species at either the continental scale or within India. STRUCTURE separated most of the domesticated germplasm from wild ecotypes, and separates Australian and Asian wild species as has been found previously. Among Indian regions and states within regions, we found 36% of the variation between regions, and 64% within landraces or wilds within states. The highest level of polymorphism in wild relatives and landraces was found in Madhya Pradesh and Andhra Pradesh provinces of India representing the centre of origin and domestication of pigeonpea respectively.
A Comparative Analysis of Gene Expression Patterns and Cell Phenotypes between Cervical and Peripheral Blood Mononuclear Cells
Rachel E. Horton,Nadine Kaefer,Elijah Songok,Fernando B. Guijon,Nadia Kettaf,Geneviève Boucher,Rafick-Pierre Sekaly,T. Blake Ball,Frank A. Plummer
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0008293
Abstract: Studies of the immunological environment in the female genital tract (FGT) are critical for the development of vaccines or microbicides to halt the spread of sexually transmitted infections. Challenges arise due to the difficulties of sampling from this site, and the majority of studies have been conducted utilising peripheral blood mononuclear cells. Identifying functional differences between immune cells of the FGT and peripheral blood would aid in our understanding of mucosal immunology. We compared the gene expression profile of mononuclear cells at these two sites. Messenger RNA expression analysis was performed using gene expression arrays on matched cervical mononuclear cells and peripheral blood mononuclear cells. Further cellular phenotyping was done by 10 colour flow cytometry. Of the 22,185 genes expressed by these samples, 5345 genes were significantly differentially expressed between the cell populations. Most differences can be explained by significantly lower levels of T and B cells and higher levels of macrophages and dendritic cells in the FGT compared with peripheral blood. Several immunologically relevant pathways such as apoptosis and innate immune signalling, and a variety of cytokines and cytokine receptors were differentially expressed. This study highlights the importance of the unique immunological environment of the FGT and identifies important differences between systemic and mucosal immune compartments.
HIV-1 subtype and viral tropism determination for evaluating antiretroviral therapy options: an analysis of archived Kenyan blood samples
Raphael W Lihana, Samoel A Khamadi, Raphael M Lwembe, Joyceline G Kinyua, Joseph K Muriuki, Nancy J Lagat, Fredrick A Okoth, Ernest P Makokha, Elijah M Songok
BMC Infectious Diseases , 2009, DOI: 10.1186/1471-2334-9-215
Abstract: Remnant blood samples from consenting sexually transmitted infection (STI) patients in Nairobi were collected between February and May 2001 and stored. Polymerase chain reaction and cloning of portions of HIV-1 gag, pol and env genes was carried out followed by automated DNA sequencing.Twenty HIV-1 positive samples (from 11 females and 9 males) were analyzed. The average age of males (32.5 years) and females (26.5 years) was significantly different (p value < 0.0001). Phylogenetic analysis revealed that 90% (18/20) were concordant HIV-1 subtypes: 12 were subtype A1; 2, A2; 3, D and 1, C. Two samples (10%) were discordant showing different subtypes in the three regions. Of 19 samples checked for co-receptor usage, 14 (73.7%) were chemokine co-receptor 5 (CCR5) variants while three (15.8%) were CXCR4 variants. Two had dual/mixed co-receptor use with X4 variants being minor population.HIV-1 subtype A accounted for majority of the infections. Though perceived to be a high risk population, the prevalence of recombination in this sample was low with no dual infections detected. Genotypic co-receptor analysis showed that most patients harbored viruses that are predicted to use CCR5.The HIV/AIDS epidemic is a major global public health crisis. Currently, an estimated 33 million people worldwide are living with HIV-1 infection. The majority of cases (67%) are in sub-Saharan Africa [1,2]. Evolution of HIV-1 has assumed multiple guises which differ in geographic distribution [3]. Three groups of HIV-1 have developed across the globe: M (major), O (outlying) and N (new) [4]. Majority of HIV-1 subtypes responsible for the AIDS pandemic belong to group M and phylogenetic analysis has further classified them into 11 pure HIV-1 subtypes [5,6] and 43 circulating recombinant forms (CRFs)[7]. In Kenya, reports of diverse HIV-1 subtypes and recombinants abound [8-10]. Subtype A1 and its recombinants are the most prevalent and responsible for majority of AIDS cases [11], their presence
Microarray Analysis of HIV Resistant Female Sex Workers Reveal a Gene Expression Signature Pattern Reminiscent of a Lowered Immune Activation State
Elijah M. Songok, Ma Luo, Ben Liang, Paul Mclaren, Nadine Kaefer, Winnie Apidi, Genevieve Boucher, Joshua Kimani, Charles Wachihi, Rafick Sekaly, Keith Fowke, Blake T. Ball, Francis A. Plummer
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030048
Abstract: To identify novel biomarkers for HIV-1 resistance, including pathways that may be critical in anti-HIV-1 vaccine design, we carried out a gene expression analysis on blood samples obtained from HIV-1 highly exposed seronegatives (HESN) from a commercial sex worker cohort in Nairobi and compared their profiles to HIV-1 negative controls. Whole blood samples were collected from 43 HIV-1 resistant sex workers and a similar number of controls. Total RNA was extracted and hybridized to the Affymetrix HUG 133 Plus 2.0 micro arrays (Affymetrix, Santa Clara CA). Output data was analysed through ArrayAssist software (Agilent, San Jose CA). More than 2,274 probe sets were differentially expressed in the HESN as compared to the control group (fold change ≥1.3; p value ≤0.0001, FDR <0.05). Unsupervised hierarchical clustering of the differentially expressed genes readily distinguished HESNs from controls. Pathway analysis through the KEGG signaling database revealed a majority of the impacted pathways (13 of 15, 87%) had genes that were significantly down regulated. The most down expressed pathways were glycolysis/gluconeogenesis, pentose phosphate, phosphatidyl inositol, natural killer cell cytotoxicity and T-cell receptor signaling. Ribosomal protein synthesis and tight junction genes were up regulated. We infer that the hallmark of HIV-1 resistance is down regulation of genes in key signaling pathways that HIV-1 depends on for infection.
CD26/dipeptidyl peptidase IV (CD26/DPPIV) is highly expressed in peripheral blood of HIV-1 exposed uninfected Female sex workers
Elijah M Songok, Bernard Osero, Lyle Mckinnon, Martin K Rono, Winnie Apidi, Elizabeth J Matey, Adrienne FA Meyers, Ma Luo, Joshua Kimani, Charles Wachihi, Blake T Ball, Frank A Plummer, Solomon Mpoke
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-343
Abstract: A quantitative CD26/DPPIV plasma analysis from 100 HIV-R, 100 HIV infected (HIV +) and 100 HIV negative controls (HIV Neg) showed a significantly elevated CD26/DPPIV concentration among the HIV-R group (mean 1315 ng/ml) than the HIV Neg (910 ng/ml) and HIV + (870 ng/ml, p < 0.001). Similarly a FACs analysis of cell associated DPPIV (CD26) revealed a higher CD26/DPPIV expression on CD4+ T-cells derived from HIV-R than from the HIV+ (90.30% vs 80.90 p = 0.002) and HIV Neg controls (90.30% vs 82.30 p < 0.001) respectively. A further comparison of the mean fluorescent intensity (MFI) of CD26/DPPIV expression showed a higher DPP4 MFI on HIV-R CD4+ T cells (median 118 vs 91 for HIV-Neg, p = 0.0003). An evaluation for hyperglycemia, did not confirm Type 2 diabetes but an impaired fasting glucose condition (5.775 mmol/L). A follow-up quantitative PCR analysis of the insulin signaling pathway genes showed a down expression of NFκB, a central mediator of the immune response and activator of HIV-1 transcription.HIV resistant sex workers have a high expression of CD26/DPPIV in tandem with lowered immune activation markers. This may suggest a novel role for CD26/DPPIV in protection against HIV infection in vivo.The disease AIDS ranks as one of the most devastating scourges of mankind. Since it was identified in 1983 more than 30 million people have died and an estimated 33 million currently live with the virus [1]. The majority of HIV infections occur in Sub-Saharan Africa, where in some countries prevalence rates of more than 40% have been documented among antenatal clinic attendees [2]. Despite progress made with antiretroviral therapy, less than a half of those requiring treatment receive it and new infections far outpace those on therapy [3]. Similar to previous viral epidemics, prevention through vaccination is believed to be the best approach. However several factors including HIVs ability to integrate itself to the host genome and to constantly mutate challenge the design
Study of the Structural and Electrical Properties of Cr-Doped BiFeO3 Ceramic  [PDF]
S. S. Arafat, S. Ibrahim
Materials Sciences and Applications (MSA) , 2017, DOI: 10.4236/msa.2017.810051
Abstract: Multiferroic BiFe1-xCrxO3 (x = 0.2 and 0.4) ceramics were synthesized in a single phase. The effects of Cr3+ substitution on the crystal structure, dielectric permittivity and leakage current were investigated. Preliminary X-ray structural studies revealed that the samples had a rhombohedral perovskite crystal structure. The dielectric constant ε' significantly increased while the dielectric loss tanδ was substantially decreased with the increase in Cr3+ substitution. The temperature effect on the dielectric properties exhibited an anomaly corresponding to magneto-electric coupling in the samples and was shifted to lower temperatures with the increase in Cr3+ substitution. The leakage current density also reduced in magnitude with the increase in the Cr3+ substitution.
Degree Splitting of Root Square Mean Graphs  [PDF]
S. S. Sandhya, S. Somasundaram, S. Anusa
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.66086
Abstract: Let \"\" be an injective function. For a vertex labeling f, the induced edge labeling \"\" is defined by, \"\" or \"\"; then, the edge labels are distinct and are from \"\". Then f is called a root square mean labeling of G. In this paper, we prove root square mean labeling of some degree splitting graphs.
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