Epidemic History and Evolutionary Dynamics of Hepatitis B Virus Infection in Two Remote Communities in Rural Nigeria

BACKGROUND: In Nigeria, hepatitis B virus (HBV) infection has reached hyperendemic levels and its nature and origin have been described as a puzzle. In this study, we investigated the molecular epidemiology and epidemic history of HBV infection in two semi-isolated rural communities in North/Central Nigeria. It was expected that only a few, if any, HBV strains could have been introduced and effectively transmitted among these residents, reflecting limited contacts of these communities with the general population in the country. METHODS AND FINDINGS: Despite remoteness and isolation, approximately 11% of the entire population in these communities was HBV-DNA seropositive. Analyses of the S-gene sequences obtained from 55 HBV-seropositive individuals showed the circulation of 37 distinct HBV variants. These HBV isolates belong predominantly to genotype E (HBV/E) (n=53, 96.4%), with only 2 classified as sub-genotype A3 (HBV/A3). Phylogenetic analysis showed extensive intermixing between HBV/E variants identified in these communities and different countries in Africa. Quasispecies analysis of 22 HBV/E strains using end-point limiting-dilution real-time PCR, sequencing and median joining networks showed extensive intra-host heterogeneity and inter-host variant sharing. To investigate events that resulted in such remarkable HBV/E diversity, HBV full-size genome sequences were obtained from 47 HBV/E infected persons and P gene was subjected to Bayesian coalescent analysis. The time to the most recent common ancestor (tMRCA) for these HBV/E variants was estimated to be year 1952 (95% highest posterior density (95% HPD): 1927-1970). Using additional HBV/E sequences from other African countries, the tMRCA was estimated to be year 1948 (95% HPD: 1924-1966), indicating that HBV/E in these remote communities has a similar time of origin with multiple HBV/E variants broadly circulating in West/Central Africa. Phylogenetic analysis and statistical neutrality tests suggested rapid HBV/E population expansion. Additionally, skyline plot analysis showed an increase in the size of the HBV/E-infected population over the last approximately 30-40 years. CONCLUSIONS: Our data suggest a massive introduction and relatively recent HBV/E expansion in the human population in Africa. Collectively, these data show a significant shift in the HBV/E epidemic dynamics in Africa over the last century

Une zone urbaine sensible avec vue sur la mer : le quartier du Chemin Vert à Boulogne-sur-Mer (Pas-de-Calais) approche interdisciplinaire sur les inégalités écologiques et inégalités sociales : Partie 2, Chapitre 6

[Departement_IRSTEA]Territoires [TR1_IRSTEA]DTAMNational audienceEn référence à la double dimension sociale et territoriale des inégalités écologiques, les auteurs ont mobilisé les méthodologies de la géographie, de l'aménagement et de la sociologie pour étudier le sens de cette notion et les liens entres inégalités écologiques et sociales dans un territoire où les recherches sur ce thème sont encore exploratoires

Determination and quantification of major climatic parameters influencing the CO\u3csub\u3e2\u3c/sub\u3e of Lascaux Cave

© 2017, Springer-Verlag GmbH Austria. High and low CO2 partial pressure (Pco2) levels can induce consequences to the internal system of a karstic cave. This then can further affect the state of the cave. Subsequently, speleothem growths and the walls with prehistorical paintings and engravings will be affected with either calcite dissolution or precipitation. Thus, pinpointing the major components of Pco2 is found indispensable. In this paper, a method is proposed in order to (1) identify the major components of the Pco2 and (2) quantify each specific contribution to the Pco2. Pco2, air temperature, air pressure, and water flow were measured from 2008 to 2010 in Lascaux Cave (Southwest of France). Pco2 varied from 0.62% (6200 ppm) in summer to 0.04% (400 ppm) in winter. We identified three major components: (1) seasonal: component A; (2) low frequency: component B; and (3) high frequency: component C. The method is applied to estimate the contribution of each component. Component A was modelled with a sinusoid curve fitted to the Pco2 measures. This component was subtracted from the measured Pco2. Then, from the remaining value of Pco2, Fourier transform, frequency filtering, and inverse Fourier transform were applied to separate high- and low-frequency components. As a result, the seasonal component A contributes 77% of the measured Pco2, while components B and C supply 13 and 11%, respectively. The three identified components have links with environmental parameters such as temperature, water flow, and atmospheric pressure. Hypotheses were proposed to describe these links. Knowledge on these aspects can help in cave management and protection specifically in answering the question: which parameter should be given more attention. [Figure not available: see fulltext.]

High precision levelling supporting the International comparison of Absolute Gravimeters

International audienceHigh precision levelling is an indispensable method used to monitor benchmark and terrain stability at the Bureau International des Poids et Mesures (BIPM). Associated with the International Comparison of Absolute Gravimeters (ICAG), levelling measurements were carried out repeatedly over the past decades. A local gravity field strongly depends on vertical terrain deformation. 1 cm displacement implies about 2 μGal change in the vertical gravity acceleration. The precision of absolute and relative gravimetry nowadays is about 1 μGal. At the beginning of the century, a strategy was outlined that the ICAG should be upgraded to a metrological Key Comparison of the CIPM MRA (Mutual Recognition Arrangement) recognized officially by the designated governmental organizations. As a result of this decision, BIPM site B was constructed and completed in Spring 2001. The site B pillar is 4m × 6m × 1.5m in dimension and more than 80 ton in weight. Such a large, newly built concrete body produces local deformation due to its sinking or tilting. This in turn influences the local gravity field. Rigorous levelling measurements have been performed by the Bureau de Recherches G'eologiques et Mini'eres (BRGM), France, since 2001 and repeated together with the 4-year ICAGs of 2001, 2005 and 2009. ICAG-2009 was characterized by becoming the first Comit'e International des Poids et Mesures (CIPM) Key Comparison which supported meanwhile the BIPM watt balance (WB) project. The WB pillar was built in Spring 2009. The Institut G'eographique National (IGN), France, has hence been invited to participate in the levelling. The latter also measured the link between the BIPM local network and external stations of the French national height reference system IGN69. In this paper, we report the final results of the levelling programmes of 2001, 2005 and 2009 and compare the results. We investigate stability of the BIPM gravity-levelling stations. We conclude that the existing and the newly built stations can be considered as stable for the purposes of the ICAGs and the WB, although further repeat measurement may be required for the WB site. For the first time, detailed and complete levelling data and results are published5. After 30 years of organizing and holding eight ICAGs, the BIPM will hand over the KC ICAG-2013 to another CIPM MRA designated institute. This paper serves as a technical and historical report of precision levelling, a sub-task of the ICAGs

Simultaneous bilateral total knee arthroplasty. A multicenter feasibility study

SummaryIntroductionThe value and risk of simultaneous total knee arthroplasty (TKA) in patients with bilateral knee arthritis is a subject of debate.HypothesesThe risk of complications following simultaneous bilateral TKA will be increased compared to the rates published in the literature for unilateral TKA, and the clinical and functional outcomes will be poorer in this particular group.Materials and methodsOne hundred and twenty-three patients who underwent simultaneous bilateral TKA between 2005 and 2011 in five specialized, high volume centers were evaluated. The files were analyzed retrospectively after a mean 33months of follow-up.ResultsThe mean hospital stay was 11days. Mean blood loss was 4.1g/dL. A postoperative transfusion was performed in 68 patients (55%), with a mean 3.1 units of blood. The mean global IKS score increased from 90 to 150 points. Eighty patients would agree to undergo simultaneous bilateral TKA again (65%), and 70 would recommend this procedure to others (57%).DiscussionThe hypothesis was not confirmed: the risk of complications was not increased compared to the generally accepted risk of a unilateral procedure. The risk of complications in this study was very similar to that published in the literature for the same therapeutic strategy. Therefore, there is no solid medical evidence to prevent recommending this strategy. The results of the participating centers suggest that this therapeutic approach should be continued in selected indications.Level of evidenceIV, retrospective study

The Recall in France: A long standing and unresolved debate

International audienc

Finite element analysis of the vibrations of waveguides and periodic structures

Many structural components can be regarded as waveguides. They are uniform in one direction so that the cross section of the waveguide has the same physical and geometric properties at all points along the axis of the waveguide. In this paper a method is presented to calculate the forced response of such a structure using a combination of wave and finite element (FE) approaches. The method involves post-processing a conventional, but low order, FE model in which the mass and stiffness matrices are typically found using a conventional FE package. A section of the waveguide is meshed and the eigenvalues and eigenvectors of the resulting transfer matrix found. The eigenvectors form a set of basis functions for the analysis of the structure as a whole, allowing the global dynamic stiffness matrix to be built easily and then the forced response to be calculated very efficiently. The main advantage of the approach over the alternative waveguide/FE approach often termed the spectral FE method, is that conventional FE packages can be used to form the stiffness and mass matrices so that structures with complex geometries or material distributions can be analysed with relative ease. To demonstrate the efficacy of the method examples of the forced response for a finite beam and plate-strip are presented

Determination and quantification of major climatic parameters influencing the CO2 of Lascaux Cave

High and low CO2 partial pressure (Pco2) levels can induce consequences to the internal system of a karstic cave. This then can further affect the state of the cave. Subsequently, speleothem growths and the walls with prehistorical paintings and engravings will be affected with either calcite dissolution or precipitation. Thus, pinpointing the major components of Pco2 is found indispensable. In this paper, a method is proposed in order to (1) identify the major components of the Pco2 and (2) quantify each specific contribution to the Pco2. Pco2, air temperature, air pressure, and water flow were measured from 2008 to 2010 in Lascaux Cave (Southwest of France). Pco2 varied from 0.62% (6200 ppm) in summer to 0.04% (400 ppm) in winter. We identified three major components: (1) seasonal: component A; (2) low frequency: component B; and (3) high frequency: component C. The method is applied to estimate the contribution of each component. Component A was modelled with a sinusoid curve fitted to the Pco2 measures. This component was subtracted from the measured Pco2. Then, from the remaining value of Pco2, Fourier transform, frequency filtering, and inverse Fourier transform were applied to separate high- and low-frequency components. As a result, the seasonal component A contributes 77% of the measured Pco2, while components B and C supply 13 and 11%, respectively. The three identified components have links with environmental parameters such as temperature, water flow, and atmospheric pressure. Hypotheses were proposed to describe these links. Knowledge on these aspects can help in cave management and protection specifically in answering the question: which parameter should be given more attention