Université Nantes Angers Le Mans

About: Université Nantes Angers Le Mans is a education organization based out in Nantes, France. It is known for research contribution in the topics: Geology & Finite element method. The organization has 434 authors who have published 249 publications receiving 7208 citations. The organization is also known as: PRES Universite Nantes Angers Le Mans.

Osteoprotegerin Induces CD34+ Differentiation in Endothelial Progenitor Cells.

Abstract: Endothelial progenitor cells (EPCs) are the main hypothetical cells that could give rise to vessels and in particular one subtype isolated from peripheral or cord bloods: endothelial colony forming cells (ECFCs). These ECFCs are clonogenic precursors committed to endothelial lineage and have robust vasculogenic properties. However, their low number and poor expansion properties when isolated from human adult bloods, currently limit their use as an autologous cell therapy product. We previously reported that osteoprotegerin (OPG), a well-characterized regulator of bone metabolism, contributes to ischemic tissue revascularization, tumor growth in vivo, and potentiates ECFCs proangiogenic properties through the secretion of SDF-1. The current study investigated the role of OPG in ECFCs differentiation and expansion from cord blood CD34+ cells. OPG increased the number of ECFCs after endothelial differentiation of CD34+ cells, enhancing the time of EPCs colonies initial appearance and the growth kinetic of endothelial cell progeny. OPG-exposed ECFCs expressed higher levels of CD34+ compared to control ECFCs. In conclusion, our findings provide novel insights into OPG in regulation of CD34+ progenitor cells. These results give new opportunities for ex vivo expansion of human ECFCs using OPG as a cell culture component for future ECFC product manufacture according to GMP.

Influence of Sliding Interfaces on the Response of a Viscoelastic Pavement

Abstract: This article aims at analyzing the influence of the perfect-slip interface condition on the computed response of a pavement structure. This condition has been implemented in the ViscoRoute software that solves the 3D mechanical problem of a multilayered viscoelastic pavement under moving loads. In the calculations, the load speed is assumed to be constant and the viscoelastic behavior of asphalt layers is represented by the Huet-Sayegh model. The dynamic equations are first solved in the frequency domain. A Fast Fourier Transformation is then employed to get the solution in the spatial domain. The effect of sliding interfaces and temperature are analyzed through an example dealing with composite pavements. In this context, the designing fields commonly used in France appear to be strongly influenced by the viscoelastic behavior of asphalt layers and the interlayer condition. This influence is quite noticeable on the deflection.

A Multi-linear Fatigue Life Model of Flexible Pavements under Multiple Axle Loadings

Abstract: The fatigue damage of a pavement under repeated traffic loadings is a key issue for pavement design. At the material scale, the fatigue performance of asphalt mixtures can be assessed with laboratory tests. The standard fatigue test consists of the application of a continuous sinusoidal signal on the specimens and enables to write the fatigue life as a function of the strain level. Real loadings are more complex. Additional parameters may therefore have an influence on the fatigue life of bituminous mixtures. A methodology for a better calculation of the fatigue life of asphalt pavements is developed. It couples a structural approach and a material-based approach. This paper presents the material-based approach of the methodology. A database of laboratory fatigue tests with complex loadings has been built. An experimental plan whose variables are the independent shape parameters characterising a loading signal is defined and the synthetic complex loading signals constructed. The results of the fatigue tests enabled the calibration of a multi-linear fatigue model where the fatigue life is a function of the independent shape parameters characterizing the loading signal. Coupling the multi-linear fatigue model with a pavement model enables the calculation of the fatigue life of a pavement under different loading conditions.