PLoS ONE

Lyme disease is a multisystemic disorder caused by B. burgdorferi sl. The molecular basis for specific organ involvement is poorly understood. The skin plays a central role in the development of Lyme disease as the entry site of B. burgdorferi in which specific clones are selected before dissemination. We compared the skin inflammatory response (antimicrobial peptides, cytokines and chemokines) elicited by spirochete populations recovered from patients presenting different clinical manifestations. Remarkably, these spirochete populations induced different inflammatory profiles in the skin of C3H/HeN mice. As spirochete population transmitted into the host skin is heterogeneous, we isolated one bacterial clone from a population recovered from a patient with neuroborreliosis and compared its virulence to the parental population. This clone elicited a strong cutaneous inflammatory response characterized by MCP-1, IL-6 and antimicrobial peptides induction. Mass spectrometry of this clone revealed 110 overexpressed proteins when compared with the parental population. We further focused on the expression of nine bacterial surface proteins. bb0347 coding for a protein that interacts with host fibronectin, allowing bacterial adhesion to vascular endothelium and extracellular matrix, was found to be induced in host skin with another gene bb0213 coding for a hypothetical protein. These findings demonstrate the heterogeneity of the B. burgdorferi ss population and the complexity of the interaction involved early in the skin

Conception et validation de stratégies de stimulation pour l'optogénétique

A million and a half people suffer from Retinitis Pigmentosa, a family of inherited diseases leading to degeneration of the retina. The disease begins with the loss of night vision and peripheral visual field and leads to total blindness. Due to the heterogeneity of the genetic mutations responsible for the disease, emerging solutions aim to compensate for the symptoms of the disease rather than curing it. These retinal prostheses have three elements: (i) a camera filming the scene in front of the patient, usually mounted on a pair of glasses, (ii) a stimulation device controlling a part of the neuronal activity of the patient and (iii) a processor that implements the transformation between the output signal of the camera and the stimulation commands. The work presented in this thesis contributes to the work of GenSight Biologics to develop such a retinal prosthesis. The project combines two recent technologies, a neuromorphic camera in which each pixel acquires the signal in an asynchronous manner, and a very high temporal resolution, and optogenetics which makes the targeted neurons photoexcitable. My work spans the entire chain of signal processing. We first present an algorithm extracting the spatial frequencies of the video from the asynchronous measurement stream emitted by the camera. Next, we focus on the Brain-Machine Interface by developing a model of the transformation linking the projected light signal and the trains of action potential triggered by the patient's retinal ganglion cells.Un million et demi de personnes souffrent de la Rétinopathie Pigmentaire, une famille de maladies héréditaires entraînant une dégénérescence de la rétine. La maladie commence par la perte de la vision nocturne et du champ visuel périphérique et mène à une cécité totale. En raison de l'hétérogénéité des mutations génétiques responsables de la maladie, des solutions visant à compenser les symptômes de la maladie émergent. Ces prothèses rétiniennes comportent trois éléments : (i) une caméra filmant la scène devant le patient, habituellement montée sur une paire de lunettes et (ii) un dispositif de stimulation qui est capable de contrôler une partie de l'activité neuronale du patient et (iii) un processeur qui implémente la transformation entre le signal de sortie de la caméra et les commandes de stimulation. Le travail présenté dans cette thèse contribue au travail de GenSight Biologics pour développer une telle prothèse rétinienne. Le project combine deux technologies récentes, une caméra neuromorphique dans laquelle chaque pixel acquiert le signal d'une manière asynchrone, et une très haute résolution temporelle, et l'optogénétique qui permet de rendre les neurones ciblés photoexcitables. Mon travail s'étend sur l'ensemble de la chaîne de traitement du signal. Nous présentons tout d'abord un algorithme extrayant les fréquences spatiales de la vidéo à partir du flux de mesures asynchrones émises par la caméra. Ensuite, nous nous concentrons sur l'Interface Cerveau-Machine en développant un modèle de la transformation reliant le signal lumineux projeté par les lunettes et les trains de potentiels d'action déclenchés par les cellules ganglionnaires de la rétine du patient

Conception et validation de stratégies de stimulation pour l'optogénétique

A million and a half people suffer from Retinitis Pigmentosa, a family of inherited diseases leading to degeneration of the retina. The disease begins with the loss of night vision and peripheral visual field and leads to total blindness. Due to the heterogeneity of the genetic mutations responsible for the disease, emerging solutions aim to compensate for the symptoms of the disease rather than curing it. These retinal prostheses have three elements: (i) a camera filming the scene in front of the patient, usually mounted on a pair of glasses, (ii) a stimulation device controlling a part of the neuronal activity of the patient and (iii) a processor that implements the transformation between the output signal of the camera and the stimulation commands. The work presented in this thesis contributes to the work of GenSight Biologics to develop such a retinal prosthesis. The project combines two recent technologies, a neuromorphic camera in which each pixel acquires the signal in an asynchronous manner, and a very high temporal resolution, and optogenetics which makes the targeted neurons photoexcitable. My work spans the entire chain of signal processing. We first present an algorithm extracting the spatial frequencies of the video from the asynchronous measurement stream emitted by the camera. Next, we focus on the Brain-Machine Interface by developing a model of the transformation linking the projected light signal and the trains of action potential triggered by the patient's retinal ganglion cells.Un million et demi de personnes souffrent de la Rétinopathie Pigmentaire, une famille de maladies héréditaires entraînant une dégénérescence de la rétine. La maladie commence par la perte de la vision nocturne et du champ visuel périphérique et mène à une cécité totale. En raison de l'hétérogénéité des mutations génétiques responsables de la maladie, des solutions visant à compenser les symptômes de la maladie émergent. Ces prothèses rétiniennes comportent trois éléments : (i) une caméra filmant la scène devant le patient, habituellement montée sur une paire de lunettes et (ii) un dispositif de stimulation qui est capable de contrôler une partie de l'activité neuronale du patient et (iii) un processeur qui implémente la transformation entre le signal de sortie de la caméra et les commandes de stimulation. Le travail présenté dans cette thèse contribue au travail de GenSight Biologics pour développer une telle prothèse rétinienne. Le project combine deux technologies récentes, une caméra neuromorphique dans laquelle chaque pixel acquiert le signal d'une manière asynchrone, et une très haute résolution temporelle, et l'optogénétique qui permet de rendre les neurones ciblés photoexcitables. Mon travail s'étend sur l'ensemble de la chaîne de traitement du signal. Nous présentons tout d'abord un algorithme extrayant les fréquences spatiales de la vidéo à partir du flux de mesures asynchrones émises par la caméra. Ensuite, nous nous concentrons sur l'Interface Cerveau-Machine en développant un modèle de la transformation reliant le signal lumineux projeté par les lunettes et les trains de potentiels d'action déclenchés par les cellules ganglionnaires de la rétine du patient

Probabilistic evaluation of changes in dynamic properties of structures

International audienceIn this article, we present a new methodology using advanced signal processing to monitor small changes in dynamic properties using model response equations, relying on a non-linear state-space approach. Fully Bayesian probabilistic methods, called Particle Smoothers (PS), are employed to provide instantaneous estimations of dynamic parameters distributions through time. In another specific case, when dynamic parameters to be estimated are the damping ratio and resonant frequency, a process based on the continuous wavelet transform (CWT) can be used. We show the superiority of our method even in this specific case. The proposed methodology gives a measurement of the goodness of the fit with simulations; thus, allowing a comparison between models. An application to Resonant Column testing is presented

Experimental and theoretical approach of the hydrolysis of pelleted magnesium alloys scraps

Industrial Mg alloys scraps containing 3% of Al and 3% of Zn (and about 20% of MgO and Mg(OH)2) were ball milled with the addition of 5wt.% C and 5 wt.% of Ni, Cu, Co or SiO2. 3 hours of ball milling were needed to obtain optimum hydrolysis performances of the mixtures (e.g. yields of almost 90% obtained within 1 minute). Pellets of such obtained powder were prepared as it is easier for an application. The shape of the hydrolysis curves highlights first an incubation period depending on the compactness of the pellets and then a second part with a logarithmic shape. A new model is presented that allows to take into account both parts of the hydrolysis curve. The model is applied successfully to all the pellets having various compactness

Skin Interface, a Key Player for Borrelia Multiplication and Persistence in Lyme Borreliosis

International audienceThe skin plays a key role in vector-borne diseases because it is the site where the arthropod coinoculates pathogens and its saliva. Lyme borreliosis, particularly well investigated in this context, is a multisystemic infectious disease caused by Borrelia burgdorferi sensu lato and transmitted by the hard tick Ixodes. Numerous in vitro studies were conducted to better understand the role of specific skin cells and tick saliva in host defense, vector feeding, and pathogen transmission. The skin was also evidenced in various animal models as the site of bacterial multiplication and persistence. We present the achievements in this field as well as the gaps that impede comprehensive knowledge of the disease pathophysiology and the development of efficient diagnostic tools and vaccines in humans. Copyright © 2020 Elsevier Ltd. All rights reserved

Faster is better: Visual responses to motion are stronger for higher refresh rates

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Phenotypic adaptation of Pseudomonas aeruginosa in the presence of siderophoreantibiotic conjugates during epithelial cell infection

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