Publications by authors named "Nicolas Keller"

Background: Establishing the optimal timing for creating vascular access in patients with chronic kidney disease (CKD) is a critical and challenging aspect of patient management. The Kidney Disease: Improving Global Outcomes guidelines propose using a 40% 2-year threshold based on the Kidney Failure Risk Equation (KFRE) for this purpose. However, the effectiveness of this threshold compared with traditional methods, such as estimated glomerular filtration rate (eGFR), is not well-established.

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Industrial waste management is an urgent problem to solve possibly by recycling, reuse and recovery of resources. In this framework, the sludge of the TiO manufacturing, called tionite, is of certain interest because it contains metallic oxide-bearing impurities, dangerous to the environment. Hence, we propose a strategy to recover TiO from tionite, towards its effective re-use as a photocatalyst.

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Introduction: Colchicine, commonly used in gout flare, is contraindicated in severe chronic kidney disease (CKD) (estimated glomerular filtration rate <30 mL/min). However, in this context, there are few alternatives, and colchicine use persists. We evaluated the tolerance of colchicine and its efficacy in patients with severe CKD.

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Hydrogen peroxide is a powerful and green oxidant that allows for the oxidation of a wide span of organic and inorganic substrates in liquid media under mild reaction conditions, and forms only molecular water and oxygen as end products. Hydrogen peroxide is therefore used in a wide range of applications, for which the well-documented and established anthraquinone autoxidation process is by far the dominating production method at the industrial scale. As this method is highly energy consuming and environmentally costly, the search for more sustainable synthesis methods is of high interest.

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The cilgavimab-tixagevimab combination retains a partial in vitro neutralizing activity against the current SARS-CoV-2 variants of concern (omicron BA.1, BA.1.

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Background: All chronic kidney diseases in diabetic patients are not diabetic kidney diseases. The objective was to compare the clinical characteristics, survival and access to transplantation in diabetic patients starting dialysis and classified either as diabetic kidney disease (DKD) or non-diabetic kidney disease in diabetic patients (NDKD).

Methods: We used the nationwide French REIN registry to analyse baseline clinical characteristics at dialysis inception and outcomes defined as kidney transplantation, deaths and their causes.

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Introduction: There are only scarce data regarding the cardiovascular impact of arteriovenous fistula after kidney transplantation depending on fistula flow.

Methods: We performed a single-center, prospective, cohort study including 49 patients with a functional fistula at 1 year from kidney transplantation. Patients were convened for a clinical work-up, a biological analysis, a fistula's Doppler ultrasonography and an echocardiography.

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Photoassisted synthesis is as a highly appealing green procedure for controlled decoration of semiconductor catalysts with co-catalyst nanoparticles, which can be carried out without the concourse of elevated temperatures, external chemical reducing agents or applied bias potential and in a simple slurry reactor. The aim of this study is to evaluate the control that such a photoassisted method can exert on the properties of ruthenium nanoparticles supported on TiO by means of the variation of the incident irradiance and hence of the photodeposition rate. For that purpose, different Ru/TiO systems with the same metal load have been prepared under varying irradiance and characterized by means of elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy.

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Background: Residual albuminuria is associated with an increased risk of progression to ESKD. We tested whether a supplementation with native vitamin D could reduce albuminuria in stable CKD patients under maximal renin-angiotensin system (RAS) blockade.

Methods: We conducted a randomized controlled study of high (cholecalciferol 100 000 UI per 10 days over 1 month) vs low-dose (ergocalciferol 400 UI/days over 1 month) supplementation with native vitamin D on urinary albumin/creatinine ratio, blood pressure and the RAS over 1 month in stable CKD patients with albuminuria and maximum tolerated RAS blockade.

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Ti-modified LaFeO/β-SiC alveolar foams were used as immobilized, highly robust dual catalysts with combined photocatalytic wet peroxide oxidation and photocatalytic activity under UV-A light. They were prepared by incipient wetness impregnation of a β-SiC foam support, by implementing a sol-gel Pechini synthesis at the foam surface in the presence of dried amorphous sol-gel titania as a titanium source. The physicochemical and catalytic features suggest the stabilization at the foam surface of a substituted LaTiFeO catalyst analogous to its powdery counterpart.

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Virtually transparent photocatalytic multilayer films composed of TiO nanoparticles and polyelectrolytes were built on model surfaces using layer-by-layer assembly and investigated as photocatalytic nanoporous coatings. Formic acid (HCOOH) and were used as models for the degradation of gaseous pollutants and for studying antibacterial properties. Positively charged TiO nanoparticles were coassembled with negatively charged poly(sodium 4-styrenesulfonate) (NaPSS) which leads to highly transparent nanoscale coatings in which the content of TiO particles is controlled mainly by the number of deposition cycles and the enhanced translucency with respect to titania powders is likely due to the presence of the polyelectrolytes in the interstitial space between the particles.

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Background: Data on coronavirus disease 2019 (COVID-19) in immunocompromised kidney transplant recipients (KTR) remain scanty. Although markers of inflammation, cardiac injury, and coagulopathy have been previously associated with mortality in the general population of patients with COVID-19, their prognostic impact amongst KTR with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has not been specifically investigated.

Methods: We conducted a cohort study of 49 KTR who presented with COVID-19.

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Photocatalytic antibacterial and biofilm-preventive activity in liquid of heavy-metal-free coatings based on a phosphorus (P)- and fluorine (F)-modified TiO photocatalyst has been investigated. They reveal significantly higher immediate and longer-term (biofilm-preventive) inactivation capacity than a reference coating made of the commercial photocatalyst TiO P25 on three bacterial species differing in cell wall type and ability to resist oxidative stress (, , ) (up to more than 99% reduction of colonization on P/F-modified TiO coating compared to about 50% on P25 TiO coating for 10 min UV-A illumination). This results from the P- and F-induced improvement of photocatalyst properties and from the smoother surface topography, which shortens reactive oxygen species (ROS) diffusion to the outer membrane of the targeted adhered bacteria.

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Background: There are only scarce data regarding the presentation, incidence, severity and outcomes of coronavirus disease 2019 (COVID-19) in patients undergoing long-term haemodialysis (HD). A prospective observational study was conducted in eight HD facilities in Alsace, France, to identify clinical characteristics of HD patients with COVID-19 and to assess the determinants of the risk of death.

Methods: All HD patients tested positive for COVID-19 from 5 March to 28 April 2020 were included.

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LaFeO@TiO heterojunction composites with a core-shell porous structure and LaFeO contents in the 2.5-25 wt.% range have been synthesized via consecutive sol-gel syntheses and tested for the photocatalytic oxidation of the myclobutanil pesticide in water under solar light and pure visible light.

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Viticulture is one of the crops most subject to pest control by fungicides. Their drainage towards the fresh water affects the aquatic environment, the fauna, the flora and especially the human health. It is therefore necessary to find an adequate solution to solve this problem.

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Coating-free TiO@β-SiC photocatalytic composite foams gathered within a ready-to-use shell/core alveolar medium the photocatalytically active TiO phase and the β-SiC foam structure were prepared a multi-step shape memory synthesis (SMS) replica method. They were fabricated following a sequential two-step carburization approach, in which an external TiC skin was synthesized at the surface of a β-SiC skeleton foam obtained from a pre-shaped polyurethane foam during a first carburization step. The adsorption behaviour of the shell/core TiO@β-SiC composite foams towards the Diuron pollutant in water was tuned by submitting the carbide foams to a final calcination treatment within the 550-700 °C temperature range.

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Ferrites are a large class of oxides containing Fe and at least another metal cation that have been investigated for and applied to a wide variety of fields ranging from mature technologies like circuitry, permanent magnets, magnetic recording and microwave devices to the most recent developments in areas like bioimaging, gas sensing and photocatalysis. In the last respect, although ferrites have been less studied than other types of semiconductors, they present interesting properties such as visible light absorption, tuneable optoelectronic properties and high chemical and photochemical stability. The versatility of their chemical composition and of their crystallographic structure opened a playground for developing new catalysts with enhanced efficiency.

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Introduction: Hemodialysis patients with contraindication to systemic anticoagulation require a heparin-free hemodialysis technique. Among several alternatives to heparin, predilution hemodiafiltration (HDF) is often used, albeit without any confirmation of its effectiveness.

Methods: Patients hospitalized in a nephrology ICU and hemodialysed for stage 5 CKD or AKI and with contraindication to systemic anticoagulation were randomized to either standard HD with a polysulfone membrane, or to predilution HDF with the same membrane.

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Introduction: Chronic kidney disease is associated with a high likelihood of receiving cardiovascular drugs. The Haute Autoritéde santé in France still recommends the use of the Cockcroft and Gault formula for dosage adjustments, on the pretext that it is the main data available in the Vidal drug database. To verify this assumption, we conducted a systematic review of the Vidal database by looking for the method recommended for evaluating renal function for the purpose of dose adjustment of cardiovascular drugs.

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Background: BK polyomavirus associated nephropathy (BKPyVAN) is a significant clinical issue in kidney transplant (KT) recipients. No specific therapy is currently available, although treatment with leflunomide may be part of the therapeutic strategy. Here, we sought to examine the impact of leflunomide on the evolution of BKPyVAN.

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Ru/TiO₂ are promising heterogeneous catalysts in different key-reactions taking place in the catalytic conversion of biomass towards fuel additives, biofuels, or biochemicals. TiO₂ supported highly dispersed nanometric-size metallic Ru catalysts were prepared at room temperature via a solar light induced photon-assisted one-step synthesis in liquid phase, far smaller Ru nanoparticles with sharper size distribution being synthesized when compared to the catalysts that were prepared by impregnation with thermal reduction in hydrogen. The underlying strategy is based on the redox photoactivity of the TiO₂ semi-conductor support under solar light for allowing the reduction of metal ions pre-adsorbed at the host surface by photogenerated electrons from the conduction band of the semi-conductor in order to get a fine control in terms of size distribution and dispersion, with no need of chemical reductant, final thermal treatment, or external hydrogen.

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In this work, the solar light-induced redox photoactivity of ZnO semiconductor material was used to prepare CuO-ZnO composite catalysts at room temperature with a control of the chemical state of the copper oxide phase. Cu₂O-ZnO and CuO-ZnO composite catalysts were prepared by using Cu(acac)₂ in tetrahydrofuran-water and Cu(NO₃)₂ in water as metallic precursor, respectively. Prior to the implementation of the photon-assisted synthesis method, the most efficient photoactive ZnO material was selected from among different ZnO materials prepared by the low temperature polyol and precipitation methods with carbonates and carbamates as precipitation agents.

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