Development and implementation of molecular methods to genotype Plasmodium falciparum in uncomplicated malaria and severe malarial anemia in Gabon

Understanding the population structure of malaria parasites and the host-parasite interaction is of fundamental interest and may help in the development of improved anti-malarial interventions. This thesis contributes to the improvement of procedures and methods for the characterization of the malaria parasite and reports current epidemiological characteristics of Plasmodium falciparum populations in Lambaréné, Gabon. The result of this thesis encourages the use of rapid diagnostic tests (RDT) not only as a diagnostic tool but also as a source of DNA that can be subsequently used for molecular assays to assess parasite diversity, species distribution, and genetic polymorphisms (e.g. mutations associated with drug resistance) as well as diagnostic performance of RDTs on large scale. In addition, performance and resolution of a genotyping method based on size polymorphisms of the msp1 gene, by using conventional polymerase chain reaction (PCR) followed by automated capillary electrophoresis (CE) (QIAxcel system, Qiagen) has been improved. Furthermore, in order to overcome the comparatively low sensitivity of conventional PCR, a barcoding assay with 9 single nucleotide polymorphisms (SNPs) for genotyping of low-density P. falciparum infection by Taqman-probe-based end-point PCR was adapted from a published method. The alternative use of these two approaches will help to improve the accuracy of parasite genotyping, covering different types of samples, applications, and lab settings. The improved techniques were applied in two case scenarios: i) an epidemiological survey and ii) to assess parasite population structure in different compartments of the body. It was observed that in Lambaréné and surroundings, the multiplicity of infection (MOI) and prevalence of chloroquine-resistance-associated mutations remain high; particularly, in the most rural areas and despite a change in malaria control recommendations, including withdrawal of chloroquine from the market. Decreasing MOIs in central areas of Lambaréné may be the result of urbanization and its effect on transmission intensity and spread of drug resistance, which results in less diverse malaria parasite populations. 55 Within its human host, malaria parasite population structure in both severely anemic and control patients was shown to be similar between bone marrow and peripheral blood. If the differences observed in some patients is of pathophysiological importance remains to be further investigated. My thesis highlights the crucial role of adequate genotyping approaches in the development of malaria eradication tools, identifies a commonly available source of DNA for retrospective studies and suggests an improvement in the guidelines for sample collection and molecular analyses for studying malaria in endemic regions

On the regularization of solution of an inverse ultraparabolic equation associated with perturbed final data

In this paper, we study the inverse problem for a class of abstract ultraparabolic equations which is well-known to be ill-posed. We employ some elementary results of semi-group theory to present the formula of solution, then show the instability cause. Since the solution exhibits unstable dependence on the given data functions, we propose a new regularization method to stabilize the solution. then obtain the error estimate. A numerical example shows that the method is efficient and feasible. This work slightly extends to the earlier results in Zouyed et al. \cite{key-9} (2014).Comment: 19 pages, 4 figures, 1 tabl

Natural frequencies and critical loads of functionally graded single span beams resting on winkler’s elastic foundation

Natural frequencies and critical loads of functionally graded single span beams resting on Winkler’s elastic foundation with general boundary conditions are presented in this paper. The analytical model of the beam is described by using the first order shear deformation theory, however, the transverse shear stress is derived from expression of the normal stress and equilibrium equation and thus, its shear correction factor is then obtained analytically. The effective material properties of the beam are assumed to follow simple power law form. The governing equation of motion of the beam is derived based on Lagrange’s equations with specific boundary conditions satisfied with the Lagrange’s multipliers. Comparisons between the results of present study with available results in the literature show a good agreement. In addition, parametric analysis is carried out, including material distribution, boundary conditions and axial load as well as foundation factor and slenderness ratio

Efficiency of Farmer Organisations in Supplying Supermarkets with Quality Food in Vietnam

The development of supermarkets in Vietnam, as in other emerging countries, goes along with an increasing concern on the part of purchasers for food quality. The paper investigates whether farmer organisations are able to help small-scale farmers get access to supermarkets, and the role that supermarkets and public support play in their emergence and development. It is based on case studies involving a number of stakeholders marketing vegetables, flavoured rice and litchi fruit in Vietnam. The interviews investigated patterns of horizontal and vertical coordination that link farmers to supermarkets, the distribution of costs and benefits between farmers and traders along the chains in relation to the strategy of quality differentiation. Eight farmer associations that work in the form of private commercial organisations are regular supermarket suppliers for the selected products. Their ability to supply supermarkets is related to the combination of functions they make available to their members, especially as regards training to improve quality (appearance, taste, safety), quality promotion and control, for which they receive public support, as well as their participation in flexible contracts with supermarkets, shops and schools. Supermarket supply through farmer associations increases farmer incomes when compared with traditional chains, yet the situation is reported to change with the increase in supermarket competition. The paper argues that changes in farmer organisation are not only due to supplying supermarkets, but also to public and international support to food quality improvement, which have been of benefit to supermarkets.Agribusiness, Industrial Organization,

Effect of combined antioxidant supplementation on oxidative stress in myocardium from rats

"The purpose of this study was to determine the effects of a combined antioxidant supplementation on myocardial protein carbonyls (PC) and malondialdehyde (MDA) in rats after aerobic downhill running. Sixty-six male Sprague-Dawley rats were randomly assigned to either a normal diet or antioxidant supplemented diet (2,000 mg vitamin C + 1,000 IU vitamin E/kg diet) for 2 weeks. Exercised rats (N=48) ran on a rodent treadmill for 90 min at a speed of 16 m/min and - 16 degrees downhill grade. Rats were killed either at rest, immediately, 2 hrs, or 48 hrs post exercise. Rested rats were killed at the same times as the exercised rats all between 0700-1000 hrs. Ventricular tissue was analyzed for two markers of oxidative stress, PC and MDA. Only exercised rats that completed the 90 min run were included in the PC and MDA data analysis. There was a significant time main effect for PC concentration (p= 0.02) but post-hoc analysis indicated no specific time differences. However, PC approached significance (p=0.064) for the 2 hr post exercise time. There were no significant treatment or time*treatment effects for PC. MDA results showed no significant time, treatment or time*treatment effect. These data indicate that downhill running with modest intensity does not significantly increase oxidative stress in hearts as indicated by PC and MDA but a larger sample size is needed to confirm these results."--Abstract from author supplied metadata

Variation in Mitochondrial DNA of Vietnamese Pigs: Relationships with Asian Domestic Pigs and Ryukyu Wild Boars

Mitochondrial DNA (mtDNA) sequences (574 bp) of 30 Vietnamese pigs (large and small) were examined and compared with those of 61 haplotypes from wild boars and domestic pigs from various locations in Asia. The large Vietnamese pigs had genetic links to Ryukyu wild boars in southern Japan. The small Vietnamese pigs were closely related to other East Asian domestic pigs. These results indicate that Vietnamese pigs are genetically diverse and may be descendents of wild and domestic pigs from other regions of Asia

Antibacterial Nanocomposites Based on Fe 3

For the vulcanized natural rubber (NR), incorporation of silver nanoparticles (AgNPs) into the NR matrix did not exhibit the bactericidal property against Escherichia coli (E. coli). However, incorporation of AgNPs into polyethylene (PE) matrix showed good antibacterial activities to both Gram-negative and Gram-positive bacteria. In the present work, NR/PE (85/15) blends have been prepared by melt blending with presence of compatibilizer in an internal mixer. To possess antibacterial property, AgNPs (5–10 nm) or Fe3O4–Ag hybrid nanoparticles (FAgNPs, 8 nm/16 nm) were added into PE matrix before its blending with NR component. The tensile test indicated that the presence of compatibilizer in NR/PE blend significantly enhanced the tensile strength and elongation at break (up to 35% and 38% increases, resp.). The antibacterial activity test was performed by monitoring of the bacterial lag-log growth phases with the presence of nanocomposites in the E. coli cell culture reactor. The antibacterial test showed that the presence of FAgNPs in NR/PE blend had a better antibacterial activity than that obtained with the lone AgNPs. Two similar reasons were proposed: (i) the faster Ag+ release rate from the Fe3O4–Ag hybrid nanoparticles due to the electron transfer from AgNP to Fe3O4 nanoparticle and (ii) the fact that the ionization of AgNPs in hybrid nanostructure might be accelerated by Fe3+ ions

Variation in mitochondrial DNA of Vietnamese pigs: Relationships with Asian domestic pigs and Ryukyu wild boars

Mitochondrial DNA (mtDNA) sequences (574 bp) of 30 Vietnamese pigs (large and small) were examined and compared with those of 61 haplotypes from wild boars and domestic pigs from various locations in Asia. The large Vietnamese pigs had genetic links to Ryukyu wild boars in southern Japan. The small Vietnamese pigs were closely related to other East Asian domestic pigs. These results indicate that Vietnamese pigs are genetically diverse and may be descendents of wild and domestic pigs from other regions of Asia

CSA: Thực hành nông nghiệp thông minh với khí hậu ở Việt Nam

During the last five years, Vietnam has been one of the countries most affected by climate change. Severe typhoons, flooding, cold spells, salinity intrusion, and drought have affected agriculture production across the country, from upland to lowland regions. Fortunately for Vietnam, continuous work in developing climate-smart agriculture has been occurring in research organizations and among innovative farmers and entrepreneurs. Application of various CSA practices and technologies to adapt to the impact of climate change in agriculture production have been expanding. However, there is a need to accelerate the scaling process of these practices and technologies in order to ensure growth of agriculture production and food security, increase income of farmers, make farming climate resilient, and contribute to global climate change mitigation. This book aims to provide basic information to researchers, managers, and technicians and extentionists at different levels on what CSA practices and technologies can be up scaled in different locations in Vietnam