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Search Results: 1 - 10 of 86134 matches for " Raphael W. Lihana "
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Distribution of Genetic Polymorphism in the CCR5 among Caucasians, Asians and Africans: A Systematic Review and Meta-Analysis  [PDF]
Beatrice A. Ongadi, George Obiero, Raphael W. Lihana, John N. Kiiru
Open Journal of Genetics (OJGen) , 2018, DOI: 10.4236/ojgen.2018.83006
Abstract: Background: Cysteine-Cysteine Chemokine Receptor 5 (CCR5), also referred to as CD195, is a component of the mammalian cell membrane and is receptor for chemokines that are activated during cell damage and inflammations. This receptor is coded by a gene located in the human chromosome 3. A Mutation on this CCR5 through deletion of 32 base pairs results into a non-destructive gene CCR5Δ32. It enables protection against HIV infection to its homozygous carriers and slows progression of the disease to heterozygous carriers. Objective: To systematically review and establish global distribution of CCR5Δ32 allele in HIV-1 infected individuals over the history of the epidemic and compare regions inhabited by Caucasians, Asians and Africans. Methodology: This meta-analysis comprised of published papers with over 10,000 individuals from whom CCR5-Delta 32 allele was successfully genotyped and recorded. The study review period was from 1984 to 2017. The search targeted online sources such as Hinari specifically PubMed Central, Google scholar, Science Direct, Research4Life, National Center for Biotechnology Information (NCBI), OVID databases, AIDS Journal and Google. The searches were not limited to a particular publication language or study design but excluded letters of correspondence and conference presentations. Search strategy using key words from a combination of Medical Subject Heading (MeSH) and free text including terms related to CCR5, CCR5Δ32 and HIV were performed in Medical Literature Analysis and Retrieval System Online (MEDLINE) through Ovid Open Access. Additional studies were identified by perusing the reference list of relevant and included articles. The review considered studies conducted among general population, both HIV
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
Diversity of Human Immunodeficiency Virus Type-1 Subtypes in Western Kenya  [PDF]
F. O. Adungo, M. M. Gicheru, N. I. Adungo, M. M. Matilu, R. W. Lihana, S. A. Khamadi
World Journal of AIDS (WJA) , 2014, DOI: 10.4236/wja.2014.44043
Abstract: Background: HIV/AIDS is the principal pandemic in the world today. Two viral types (HIV-1 and HIV-2), with numerous groups (M, N and O for HIV-1 and A through H for HIV-2) have emerged. These have further proliferated into numerous subtypes, sub-subtypes and circulating recombinant forms (CRF) over the last 30 years. HIV-1 variants circulate together within a geographical region providing an opportunity for recombination of viral strains within infected individuals. In Kenya, at least nine different genetic HIV-1 subtypes and several recombinant forms have been defined within group M, which accounts for the majority of cases in the AIDS pandemic. Objective: To determine the genetic diversity of HIV-1 in the western region of Kenya bordering Uganda. Methodology: A cross sectional study was carried out at Busia District Hospital between 2007 and 2009. A total of 75 patients were sampled randomly from a cohort of 1000 clients on antiretroviral therapy. Blood samples were analysed at the HIV Laboratory, Kenya Medical Research Institute, Nairobi, Kenya. PCR was carried out on the Pol region of HIV, sequenced and analysed by BLAST for subtypes. Results: BLAST analysis revealed the following circulating subtypes: 40/75 (53.30%) were HIV-1 group M subtype A1; 21/75 (28.0%) were subtype D; 5/75 (6.7%) were subtype G; 4/75 (5.30%) were subtype C; and 2/75 (2.70%) were subtype A2. Only one isolate was identified for the other subtypes viz
Pair Creation of Black Holes During Inflation
Raphael Bousso,Stephen W. Hawking
Physics , 1996, DOI: 10.1103/PhysRevD.54.6312
Abstract: Black holes came into existence together with the universe through the quantum process of pair creation in the inflationary era. We present the instantons responsible for this process and calculate the pair creation rate from the no boundary proposal for the wave function of the universe. We find that this proposal leads to physically sensible results, which fit in with other descriptions of pair creation, while the tunnelling proposal makes unphysical predictions. We then describe how the pair created black holes evolve during inflation. In the classical solution, they grow with the horizon scale during the slow roll-down of the inflaton field; this is shown to correspond to the flux of field energy across the horizon according to the First Law of black hole mechanics. When quantum effects are taken into account, however, it is found that most black holes evaporate before the end of inflation. Finally, we consider the pair creation of magnetically charged black holes, which cannot evaporate. In standard Einstein-Maxwell theory we find that their number in the presently observable universe is exponentially small. We speculate how this conclusion may change if dilatonic theories are applied.
Primordial Black Holes: Tunnelling vs. No Boundary Proposal
Raphael Bousso,Stephen W. Hawking
Physics , 1996,
Abstract: In the inflationary era, black holes came into existence together with the universe through the quantum process of pair creation. We calculate the pair creation rate from the no boundary proposal for the wave function of the universe. Our results are physically sensible and fit in with other descriptions of pair creation. The tunnelling proposal, on the other hand, predicts a catastrophic instability of de Sitter space to the nucleation of large black holes, and cannot be maintained.
Pair Creation and Evolution of Black Holes During Inflation
Raphael Bousso,Stephen W. Hawking
Physics , 1996,
Abstract: We summarise recent work on the quantum production of black holes in the inflationary era. We describe, in simple terms, the Euclidean approach used, and the results obtained both for the pair creation rate and for the evolution of the black holes.
The role of soil factors and leaf protein in the utilization of mopane plants by elephants in northern Botswana
Raphael Ben-Shahar, David W Macdonald
BMC Ecology , 2002, DOI: 10.1186/1472-6785-2-3
Abstract: Ten mopane plots were subjected to sampling of soil properties that included structure, pH, nitrogen, phosphorus, potassium contents and protein contents. Elevated nitrogen and phosphorus contents in soils correlated with high protein levels in mopane leaves. Protein levels in leaves of mopane plants differed significantly between sites. However, multivariate analyses of environmental parameters and plots suggested that on a regional scale, there was no difference in the extent of elephant damage to mopane plants due to differential protein levels in leaves or any of the underlying soi factors that were examined.From management perspective, this pattern mitigates the likelihood that an even more prolific elephant population will alter mopane woodland habitats irreversibly.The distribution range of elephant populations in southern Africa where elephants are not restricted by humans largely overlaps with the distribution of mopane (Colophospermum mopane) woodlands. Mopane is a principal food item in the diet of elephants, not only in northern Botswana [1], but also elsewhere in southern Africa [4,20,28,30]. High utilization rates of plants by prolific elephant population may result with the alteration of vegetation structure and even the decline of species diversity [9].Some mopane woodland areas in northern Botswana appear to sustain higher elephant utilization rates than neighbouring mopane areas. The availability of water from surface seasonal water sources can only partially explain the distribution of elephant browsing [1,31]. Two findings relating to factors that affect the feeding habits of other large herbivores suggest possible additional explanations for the patchy browsing by elephants on mopane. First, large herbivorous species are influenced by elevated nutrient concentrations in the forage [7,24]. And second, the feeding patterns and the differential distribution range of large herbivores can be explained by localized differences in soil factors and nutr
Prevalence, Incidence and Risk Factors for Acquisition of Herpes Simplex Virus Type 2 among Fishermen on the Shores of Lake Victoria in Kisumu County, Kenya  [PDF]
Raphael O. Ondondo, Zipporah W. Ng’ang’a, Solomon Mpoke, Michael K. Kiptoo, Elizabeth A. Bukusi
Advances in Infectious Diseases (AID) , 2014, DOI: 10.4236/aid.2014.42016

Background: Herpes simplex virus Type 2 (HSV-2) has been associated with HIV infection. More recently, HSV-2 incidence has been linked to HIV acquisition. A few studies have suggested that the fishing communities have a high HSV-2 prevalence but there is limited knowledge on HSV-2 incidence and associated risk factors among fishermen. Methods: Three hundred fishermen were consented, and evaluated for baseline HSV-2 serology status and again after 12 months among those negative at baseline. Sexual behavior and socio-demographic data were collected at enrolment and exit visits using a structured questionnaire. Baseline HIV serology and Human papillomavirus (HPV) DNA genotyping were also performed. Multivariate logistic regression was used to determine independent factors associated with HSV-2 acquisition. Results: Baseline HSV-2 prevalence was 56.3% (95% CI: 50.7 - 62.0). Factors associated with HSV-2 prevalence were, older age (aOR = 1.96; 95% CI: 1.16 - 2.85), history of STI (aOR 2.12; 95% CI: 1.19 - 3.91), infection with HIV (aOR 2.22; 95% CI: 1.17 - 4.22), ever married (aOR = 3.80; 95% CI: 1.42 - 11.90), most recent sexual act with sex worker/casual partner (OR= 3.56; 95% CI: 1.49 - 8.62) and inconsistent condom use with new sexual partner (aOR = 6.34; 95% CI: 2.24 - 13.04). The HSV-2 incidence was 23.6 (95% CI = 15.4 - 31.8)/100 pyr. Infection with persistent high-risk (HR) HPV (aIRR = 3.35; 95% CI: 1.21 - 11.37), multiple (2) partners in 12 months prior to study participation (aIRR = 4.77; 95% CI: 1.12 - 11.38), inconsistent condom use with new partner (aIRR =2.53; 95% CI: 1.12 - 7.38) and most recent sexual act with sex worker/casual partner (OR = 3.03; 95% CI: 1.17 - 8.58) were independent risk factors for HSV-2 acquisition. Conclusion: The incidence of HSV-2 is very high among fishermen. It is associated with persistent HR HPV infection and high-risk sexual behavior. Intervention strategies targeting these men with high risk sexual behavior are urgently needed to stop new HSV-2 acquisition and subsequently prevent HIV infection.

Obesity in the United States – Dysbiosis from Exposure to Low-Dose Antibiotics?
Lee W. Riley,Eva Raphael,Eduardo Faerstein
Frontiers in Public Health , 2013, DOI: 10.3389/fpubh.2013.00069
Abstract: The rapid increase in obesity prevalence in the United States in the last 20 years is unprecedented and not well explained. Here, we explore a hypothesis that the obesity epidemic may be driven by population-wide chronic exposures to low-residue antibiotics that have increasingly entered the American food chain over the same time period. We propose this hypothesis based on two recent bodies of published reports – (1) those that provide evidence for the spread of antibiotics into the American food chain, and (2) those that examine the relationship between the gut microbiota and body physiology. The livestock use of antimicrobial agents has sharply increased in the US over the same 20-year period of the obesity epidemic, especially with the expansion of intensified livestock production, such as the concentrated animal feeding operations. Observational and experimental studies support the idea that changes in the intestinal microbiota exert a profound effect on body physiology. We propose that chronic exposures to low-residue antimicrobial drugs in food could disrupt the equilibrium state of intestinal microbiota and cause dysbiosis that can contribute to changes in body physiology. The obesity epidemic in the United States may be partly driven by the mass exposure of Americans to food containing low-residue antimicrobial agents. While this hypothesis cannot discount the impact of diet and other factors associated with obesity, we believe studies are warranted to consider this possible driver of the epidemic.
Silicon Burning II: Quasi-Equilibrium and Explosive Burning
W. Raphael Hix,Friedrich-Karl Thielemann
Physics , 1998, DOI: 10.1086/306692
Abstract: Having examined the application of quasi-equilibrium to hydrostatic silicon burning in Paper I of this series, Hix & Thielemann (1996), we now turn our attention to explosive silicon burning. Previous authors have shown that for material which is heated to high temperature by a passing shock and then cooled by adiabatic expansion, the results can be divided into three broad categories; \emph{incomplete burning}, \emph{normal freezeout} and \emph{$\alpha$-rich freezeout}, with the outcome depending on the temperature, density and cooling timescale. In all three cases, we find that the important abundances obey quasi-equilibrium for temperatures greater than approximately 3 GK, with relatively little nucleosynthesis occurring following the breakdown of quasi-equilibrium. We will show that quasi-equilibrium provides better abundance estimates than global nuclear statistical equilibrium, even for normal freezeout and particularly for $\alpha$-rich freezeout. We will also examine the accuracy with which the final nuclear abundances can be estimated from quasi-equilibrium.
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