Publications by authors named "Jean-Pierre Alcaraz"

The invasive nature of sample collection for studying the small intestinal (SI) microbiome often results in its poor characterization. This study evaluated a novel ingestible medical device (MD) for SI luminal sample collection. A monocentric interventional trial (NCT05477069) was conducted on 15 healthy subjects.

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Inulin consumption and dihydrogen (H) administration both exert antitumor effects on preclinical models as well as in clinical trials. As H is one of the major byproducts of inulin fermentation by bacterial species of the gut microbiota (GM), we hypothesized that H could mediate the antitumor effects of inulin. To provide evidence in favor of this hypothesis, we first determined the pattern of H-exposure to which mice are subjected after inulin administration and developed an inhaled hydrogen therapy (HT) protocol replicating this pattern.

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. Due to its antioxidant, anti-inflammatory, anti-apoptosis, and anti-fatigue properties, molecular hydrogen (H) is potentially a novel therapeutic nutrient for patients with coronavirus acute disease 2019 (COVID-19). We determined the efficacy and safety profile of hydrogen-rich water (HRW) to reduce the risk of COVID-19 progression.

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Background: Dihydrogen (H) is produced endogenously by the intestinal microbiota through the fermentation of diet carbohydrates. Over the past few years, numerous studies have demonstrated the significant therapeutic potential of H in various pathophysiological contexts, making the characterization of its production in laboratory species of major preclinical importance.

Methods: This study proposes an innovative solution to accurately monitor H production in free-moving rodents while respecting animal welfare standards.

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Preclinical and clinical studies have shown that molecular hydrogen (H) has anti-oxidant, anti-inflammatory, and anti-apoptotic properties. Safety data are available in the literature and acute toxicity has been tested in isolated cells and laboratory animals. We have evaluates the genotoxicity of H in vivo in rats after 72 h exposure, following the International Council for Harmonization guidelines ICH S2 (R1).

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The use of liposomes as drug delivery systems emerged in the last decades in view of their capacity and versatility to deliver a variety of therapeutic agents. By means of small-angle neutron scattering (SANS), we performed a detailed characterization of liposomes containing outer membrane protein F (OprF), the main porin of the bacterium outer membrane. These OprF-liposomes are the basis of a novel vaccine against this antibiotic-resistant bacterium, which is one of the main hospital-acquired pathogens and causes each year a significant number of deaths.

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The need for personal protective equipment increased exponentially in response to the Covid-19 pandemic. To cope with the mask shortage during springtime 2020, a French consortium was created to find ways to reuse medical and respiratory masks in healthcare departments. The consortium addressed the complex context of the balance between cleaning medical masks in a way that maintains their safety and functionality for reuse, with the environmental advantage to manage medical disposable waste despite the current mask designation as single-use by the regulatory frameworks.

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A key to the development of lipid membrane-based devices is a fundamental understanding of how the molecular structure of the lipid bilayer membrane is influenced by the type of lipids used to build the membrane. This is particularly important when membrane proteins are included in these devices since the precise lipid environment affects the ability to incorporate membrane proteins and their functionality. Here, we used neutron reflectometry to investigate the structure of tethered bilayer lipid membranes and to characterize the incorporation of the NhaA sodium proton exchanger in the bilayer.

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The coronavirus infectious disease-2019 (COVID-19) pandemic has led to an unprecedented shortage of healthcare resources, primarily personal protective equipment like surgical masks, and N95/filtering face piece type 2 (FFP2) respirators. Reuse of surgical masks and N95/FFP2 respirators may circumvent the supply chain constraints and thus overcome mass shortage. Methods, design, setting, and measurement: Herein, we tested the effects of dry- and moist-air controlled heating treatment on structure and chemical integrity, decontamination yield, and filtration performance of surgical masks and FFP2 respirators.

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In 1968 Wolfson et al. published the concept for producing energy inside the body using catalytic electrodes exposed to the body fluid as an electrolyte and utilising naturally occurring fuels such as glucose. Since then, the technology has advanced to enhance the levels of power using enzymes immobilised within three-dimensional bioelectrodes that are nanostructured.

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The natural biodegradabilty of porous silicon (pSi) in physiological media limits its wider usage for implantable systems. We report the stabilization of porous silicon (pSi) membranes by chemical surface oxidation using RCA1 and RCA2 protocols, which was followed by a PEGylation process using a silane-PEG. These surface modifications stabilized the pSi to allow a long period of immersion in PBS, while leaving the pSi surface sufficiently hydrophilic for good filtration and diffusion of several biomolecules of different sizes without any blockage of the pSi structure.

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We designed a supported lipid bilayer (SLB) biomimetic membrane system that comprised polyaniline (PANI) to support a lipid bilayer membrane that incorporated Na+/H+ transporter proteins (NhaA) to give the system the capability of controllable electrogenic ion transport. The high turnover rate of NhaA (∼105 per min) provides the basis for this PANI-SLB-NhaA system to be a high-speed rechargeable biocapacitor that functions as a low-energy-consuming fast switch for biological engineering applications.

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A major problem for the detection of cancer biomarkers in plasma or serum is that common clinical practice does not require the patient to be in a fasting state. Considering that lipoproteins are the main population affected by food intake, the authors hypothesized that biomarkers could be embedded in lipid particles and thereby opens a new avenue for detection. Using the recently published biomarker, soluble VE-cadherin (sVE), the authors tested our hypothesis using techniques of biophysics, biochemistry and the tools of nanobiotechnology on serum samples from kidney cancer patients (n = 106).

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This review takes an approach to implanted medical devices that considers whether the intention of the implanted device is to have any communication of energy or materials with the body. The first part describes some specific examples of three different classes of implants, analyzed with regards to the type of signal sent to cells. Through several examples, the authors describe that a one way signaling to the body leads to encapsulation or degradation.

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There is a growing interest in the design and engineering of operational biofuel cells that can be implanted. This review highlights the recent progress in the electrochemistry of biofuel cell technologies, but with a particular emphasis on the medical and physiological aspects that impact the biocompatibility of biofuel cells operating inside a living body. We discuss the challenge of supplying power to implantable medical devices, with regard to the limitations of lithium battery technology and why implantable biofuel cells can be a promising alternative to provide the levels of power required for medical devices.

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OprF has a central role in Pseudomonas aeruginosa virulence and thus provides a putative target for either vaccines or antibiotic cofactors that could overcome the bacterium's natural resistance to antibiotics. Here we describe a procedure to optimize the production of highly pure and functional OprF porins that are then incorporated into a tethered lipid bilayer. This is a stable biomimetic system that provides the capability to investigate structural aspects and function of OprF using and neutron reflectometry and electrical impedance spectroscopy.

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Tethered lipid bilayer membranes (tBLM) are planar membranes composed of free lipids and molecules tethered to a solid planar substrate providing a useful model of biological membranes for a wide range of biophysical studies and biotechnological applications. The properties of the tBLM depend on the free lipids and on the chemistry of the tethering molecules. We present a nanoscale characterization of a tBLM composed of deuterated 1,2-dimyristoyl-sn-glycero-3-phosphocholine (d-DMPC) free lipids, benzyl disulfide undecaethylene glycol phytanol (DLP) tethering molecules, and benzyl disulfiide tetraethylene glycol polar spacer molecules (PSM) used to control the areal density of tethering molecules through coadsorption.

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An implanted biofuel cell (IBFC) is a novel device that provides the means to create electricity from glucose and oxygen, using an original architecture for the IBFC that provides efficient work inside a living organism. In the future these IBFCs will be required to power implanted devices to assist failing physiological functions in humans. The active ingredients of such IBFCs are glucose oxidase at the anode and laccase at the cathode.

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The mitochondrial voltage-dependent anion channel (VDAC) is a pivotal protein since it provides the major transport pathway between the cytosol and the mitochondrial intermembrane space and it is implicated in cell apoptosis by functioning as a gatekeeper for the trafficking of mitochondrial death molecules. VDAC is a beta-barrel channel with a large conductance, and we use it as a model transport protein for the design of biomimetic systems. To overcome the limitations of classical overexpression methods for producing and purifying membrane proteins (MPs) we describe here the use of an optimized cell-free system.

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We present a simple bench-top method to fabricate enclosed circular channels for biological experiments. Fabricating the channels takes less than 2 hours by using glass capillaries of various diameters (from 100 µm up to 400 µm) as a mould in PDMS. The inner surface of microchannels prepared in this way was coated with a thin membrane of either Matrigel or a layer-by-layer polyelectrolyte to control cellular adhesion.

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The behaviour of cancerous epithelial prostatic cells (PC3) growing on polyelectrolytes (PE) coatings was compared to the behaviour of immortalized normal prostatic cells (PNT-2). The cell behaviour was evaluated and quantified in terms of initial cell attachment, growth, metabolic activity, morphometry, adhesion, apoptosis and stress related gene expression. Both the anionic PSS (poly(sodium 4-styrenesulphonate))-terminated surface and cationic PAH (poly(allylamine hydrochloride))-terminated surfaces were not cytotoxic.

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MADS-box transcription factors play crucial roles in organ and cell differentiation in organisms ranging from yeast to humans. Most of the work on plant MADS-box proteins focused on their roles in floral development whereas less information is available on their function in fruit maturation. We cloned three distinct tomato cDNAs using a RT-PCR approach, encoding LeMADS1, LeMADS5 and LeMADS6 factors and whose mRNAs mostly accumulate in tomato flowers and fruits.

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Powering future generations of implanted medical devices will require cumbersome transcutaneous energy transfer or harvesting energy from the human body. No functional solution that harvests power from the body is currently available, despite attempts to use the Seebeck thermoelectric effect, vibrations or body movements. Glucose fuel cells appear more promising, since they produce electrical energy from glucose and dioxygen, two substrates present in physiological fluids.

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Article Synopsis
  • The study investigates the role of plant fibrillins (FIB1a, -1b, -2) in Arabidopsis using RNA interference, revealing that reduced levels of these proteins hinder long-term acclimation to combined light and cold stress.
  • Affected plants exhibit poor photosynthesis protection, abnormal membrane arrangements, slower growth, and reduced anthocyanin accumulation, all of which are reversed by jasmonate (JA) treatments.
  • The findings suggest that JA plays a crucial role in chloroplast acclimation to stress, with FIB proteins facilitating the process through their impact on plastoglobule-associated JA biosynthesis.
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Article Synopsis
  • The plastid genome in dicotyledonous plants uses three types of RNA polymerases for transcription, including PEP and two phage-like enzymes, RPOTp and RPOTmp.
  • RPOTp is crucial for chloroplast transcription and cell growth, while RPOTmp assists with rrn operon transcription during seed germination and later developmental stages.
  • Research has identified two proteins that interact with RPOTmp, one of which is a thylakoid membrane protein that keeps RPOTmp anchored in the chloroplast, suggesting that light influences RPOTmp's activity by affecting its membrane association.
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