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BACKGROUND AND AIMS Treatment with erythropoietin (EPO) is well established for anemia in chronic kidney disease patients but not well studied in acute kidney injury (AKI). This study aims to assess the transfusion need, renal recovery and all-cause mortality of AKI patients with anemia whether treated or not with EPO. METHOD This is a multicenter, randomized, pragmatic controlled clinical trial. It included 134 hospitalized patients with anemia [hemoglobin (Hb) The trial is registered on ClinicalTrials.gov (NCT03401710). RESULTS The general characteristics of both groups are summarized in Table 1. There was no statistically significant difference in transfusions, renal recovery or mortality between the treated group and the control (Table 2). A conditional regression analysis found phosphate, Hb on admission, CRP at the end of the hospitalization, the need for transfusions, the absence of renal recovery and inotrope use as factors associated with mortality (OR = 1.34, 95% CI 1.09–1.63; P = 0.004; OR = 0.61, 95% CI 0.41–0.92; P = 0.018; OR = 1.014, 95% CI 1.005–1023; P = 0.003; OR = 4.48, 95% CI 1.53–13.07; P = 0.006; OR = 22.1, 95% CI 6.36–76.74; P CONCLUSION EPO treatment in patients with AKI and anemia has no significant impact on transfusion need, renal recovery or death.

Background Treatment with erythropoietin is well established for anemia in chronic kidney disease patients but not well studied in acute kidney injury. Methods This is a multicenter, randomized, pragmatic controlled clinical trial. It included 134 hospitalized patients with anemia defined as hemoglobin n = 67) and the second received standard of care (control; n = 67) during the hospitalization until discharge or death. The primary outcome was the need for transfusion; secondary outcomes were death, renal recovery, need for dialysis. Results There was no statistically significant difference in transfusion need (RR = 1.05, 95%CI 0.65,1.68; p = 0.855), in renal recovery full or partial (RR = 0.96, 95%CI 0.81,1.15; p = 0.671), in need for dialysis (RR = 11.00, 95%CI 0.62, 195.08; p = 0.102) or in death (RR = 1.43, 95%CI 0.58,3.53; p = 0.440) between the erythropoietin and the control group. Conclusions Erythropoietin treatment had no impact on transfusions, renal recovery or mortality in acute kidney injury patients with anemia. The trial was registered on ClinicalTrials.gov (NCT03401710, 17/01/2018).

An in-situ visualisation of the microstructure of a Carbopol gel flowing in a micro-channel is presented. By means of a novel chemical protocol able to stain the solid material units of the gel with a fluorescent molecule we are able to accurately identify the solid/fluid material units advected by the confined microscopic flow. Based on this novel visualisation technique a full statistical description of the distributions of solid–fluid material units in the flow in terms of space and time averages, probability density functions and space–time correlations is reported for the first time.

Objective: This retrospective study discusses the need for induction therapy in half haplotype low immunological risk kidney transplant patients. Material and Methods: Records of 70 adult kidney transplant patients were reviewed with 3 years follow up. All patients were half haplotype matched with their living related donors and had PRA Results: We did not find any significant difference between the 2 groups regarding the length of hospital stay, the rate and severity of acute rejection, the rate of CMV infection, the occurrence of delayed graft function and the rate and type of surgical complications at 1 year. Furthermore, the patient and graft survival as well as the serum creatinine levels upon discharge and at 1, 3, 6, 12 and 36 months were also comparable. Nevertheless, the rate and type of out of Hospital infections and 1-year infection rate as well as the treatment cost were significantly higher in Group I. Conclusion: Induction therapy might not be desirable in low-immunological risk half-haplotype kidney transplant patients.

International audience; An active inline mixer suitable for flows at low Reynolds number and high Péclet number is studied. An alternated oscillatory forcing protocol is imposed by three rotating circular arc-walls in a straight channel. In the two-dimensional case, simple phenomenological arguments are used to estimate heuristically the mixing efficiency with two non-dimensional control parameters: the Strouhal number based on the bulk flow velocity, and the strength of the cross flow relative to the transport flow. The validity and limitations of the proposed mixing conditions are explained by the transport mechanisms in the mixer. The beneficial role of the elliptic flow regions for stretching and folding the passive scalar interfaces is highlighted, as well as a correlation between good mixing ability and the chaotic advection of tracers in the mixing zone.

International audience; The ability to predict and/or control wall slip is a fundamental problem in the hydrodynamics of yield stress fluids, which is poorly understood to date and has important applications in bio-and micro-fluidic systems. Systematic measurements of steady flows of a simple yield stress fluid (Carbopol Ultrez 10) in a plane acrylic micro-channel are used to establish rigorous scaling laws for the wall velocity gradient and the slip velocity. By means of epi-fluorescent microscopy combined with a custom developed Digital Particle Image Velocimetry (DPIV) technique, times series of velocity fields were measured within a wide range of flow rates and three distinct flow regimes were identified: full plug, partial plug and fully yielded. Corresponding to each flow regime, wall velocity gradients and slip velocities were obtained by extrapolating the velocity profiles using a smoothing spline function. By combining the flow field measurements with the macro-rheological measurements, scaling laws for the wall velocity gradient and the slip velocity with the wall shear stress were identified, and compared with results from the literature. Detailed microscopic measurements of the velocity field enabled an assessment of the effectiveness of a chemical treatment of the channel walls meant to suppress wall slip proposed by Metivier and coworkers, Soft Matter 8, 2012.

The question of whether Carbopol gels always behave as “model” yield stress material is addressed experimentally. Prompted by several simple hydrodynamic experiments performed with Carbopol gels that can not be fully understood within the commonly accepted “model” picture, we revisit the yielding behaviour of a Carbopol gel. When subjected to a loading/unloading process, the yielding of the Carbopol is gradual and exhibits a rheological hysteresis. By in-situ visualisation of the microstructure it is demonstrated that these features do not originate from a micro-structural damage of the micro-gel. A systematic description of the role of the rate at which the material is forced (loaded or unloaded) on the yielding scenario is given. In closing, the question of how simple a scalar model can be and yet accurately describe the experimentally observed yielding scenario of a Carbopol gel in a rheometric flow is addressed. It is concluded that simple scalar models may do such job as long as they are not too simple and include a minimal amount of physical ingredients.

International audience; The impact and stopping of a spherical object freely falling onto the surface of an elasto-viscoplastic material (an aqueous solution of Carbopol ® Ultrez 10) is studied both experimentally and theoretically. Accurate measurements of the instantaneous position of the centre of mass of the falling object allow one to calculate both the speed and acceleration of the object. To rationalise the experimental results we resort to a simple 1 − toy model initially proposed by Putz and Burghelea [1]. At early stages of the motion, the deformation of the gel is dominated by viscous effects, the model by Putz and Burghelea reduces to the well-known Herschel-Bulkley relationship and an equation of motion for the sphere can be derived. By comparing the measured trajectories, speeds and accelerations with the "viscous " analytical solution one may estimate the yield stress, the consistency and the power law index. After long enough times, the spherical object oscillates around its final stopping position and the deformation of the material is no longer viscous but elastic. Within this second asymptotic limit the model by Putz and Burghelea reduces to the Hooke's law and once more an analytical solution for the equation of motion may be readily obtained. By measuring the period of the oscillatory motion observed during this regime one may estimate the elastic modulus of the gel.

International audience

National audience; We present some results of a numerical study of the mixing of a passive scalar by chaotic advection, at low Reynolds number. The mixing is carried out by a new active open flow mixer, called RAW for Rotating Arc-Walls. A phenomenological model is proposed, making it possible to obtain a mixing criterion based on two dimensionless parameters : the Strouhal number based on the bulk velocity of the fluids and the ratio of the transverse velocity to the bulk velocity. For a given protocol corresponding to a choice of these parameters favourable for mixing in the case of a Newtonian fluid, the dependence on the Bingham number of the efficiency of the mixing of a Bingham plastic fluid is investigated. The complex role of the yield stress is evidenced.; Nous présentons quelques résultats d'une étude numérique du mélange d'un scalaire passif par advection chaotique à bas nombre de Reynolds. Le mélange est effectué par un nouveau mélangeur actif en écoulement ouvert, appelé RAW pour Rotating Arc-Walls. Un modèle phénoménologique est proposé, permettant d'obtenir un critère de mélange portant sur deux paramètres adimensionnels : le nombre de Strouhal basé sur la vitesse débitante du fluide et le rapport de la vitesse transverse d'écoulement à la vitesse débitante. Pour un protocole donné correspondant à un choix de ces paramètres favorable au mélange dans le cas d'un fluide newtonien, nous étudions la dépendance de l'efficacité du mélange d'un fluide de Bingham vis-à-vis du nombre de Bingham. Le rôle complexe du seuil de contrainte est mis en évidence.

National audience; A fundamental problem in the hydrodynamics of yield stress fluids relates to the "wall slip" phenomenon. To tackle this, we have performed systematic measurements of flow fields of a simple yield stress fluid (Carbopol Ultrez 10) in a plane acrylic made micro-channel. By means of epifluorescent microscopy combined with a customly developed Digital Particle Image Velocimetry, times series of velocity fields were measured within a wide range of driving flow rates and three distinct flow regimes were identified: full plug, partial plug and fully yielded. Corresponding to each flow regime, the wall velocity gradients and slip velocities are obtained by interpolating the velocity profiles using a smoothing spline function. Furthermore, by combining the flow field measurements with the macro-rheological measurements of the flow curves, we identify scaling laws of the slip velocity with the wall shear stress. Finally, we present a detailed comparison of the experimentally found scaling laws of the wall slip with results from the literature.

International audience

International audience

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