Purificació i anàlisi d’exosomes

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2020, Tutor: Fernando BenaventeExosomes are 30-150 nm extracellular nanovesicles that can be found in biological fluids such as blood, urine, sweat, tears, etc. They are secreted by all types of cells through exocytosis processes. Exosomes contain a wide variety of biological relevant molecules such as lipids, proteins, mRNAs, and microRNAs. They are thought to function as messengers between cells due to their ability to endocytosis and membrane fusion. Therefore, they are involved in many physiological and pathological processes, including tumor initiation and immune response. In this study, as an alternative to the techniques traditionally used to isolate exosomes, such as ultracentrifugation, it was explored polyethylene glycol (PEG) precipitation, which allows a facile, low-cost and effective isolation of exosomes from blood serum. Different variables of the method were studied, and the size of the isolated exosomes was measured by dynamic light scattering (DLS). In addition, a novel capillary electrophoresis (CE) with ultraviolet (UV) detection method was developed to complement these particle size measurements. Different concentrations of hydroxypropyl cellulose (HPC, 0.2, 0.5, 0.8% v/v) were added in the background electrolyte (BGE, 0.1 M tris + 0.25 M boric acid pH= 7.9) to reduce the adsorption of the exosomes to the inner wall of the separation capillary. The best results were obtained with a 0.5% v/v of HPC in the BGE. In order to homogenize the charge of the exosomes and make the separation only size dependent 0.1% v/v of sodium dodecyl sulfate (SDS) was also added to the BGE. Under these optimized conditions, a characteristic electrophoretic profile of the isolated exosomes was obtained, and separation showed the highest reproducibility and shortest analysis time

L’acromégalie du sujet âgé: quelles particularités?

Les adénomes somatotropes de la personne âgée sont rares, et caractérisés par un retard diagnostique, un tableau clinique peu bruyant. Leurs critères diagnostiques rejoignent ceux des patients plus jeunes. La chirurgie, si possible, reste le traitement de choix de l’acromégalie du sujet âgé. Les analogues de la somatostatine ont montré leur efficacité dans le traitement de ces patients. Le pronostic des patients acromégales est inversement corrélé à l’âge du patient, à la durée de la maladie, au dernier taux de GH sous traitement. L’âge est un déterminant majeur de la mortalité en dehors de l’évolutivité de l’acromégalie. Nous rapportons trois observations de patientes acromégales âgées respectivement de 75, 70 et 66 ans avec une revue de la littérature.Mots clés: Acromégalie, sujet âgé, chirurgie hypophysaire, pronosticEnglish Title: Acromegaly features in the aging populationEnglish AbstractSomatotroph adenomas are rare in the aging population. Diagnosis of somatotroph adenomas is often long delayed and they are characterized by atypical clinical picture. Their diagnostic criteria are similar to those used for younger patients. Surgery, if possible, is the treatment of choice for acromegaly in the elderly. Somatostatin analogues have shown to be effective in these patients. Prognosis is inversely correlated with patient’s age, duration of disease and last GH level under treatment. Beside evolution of disease, age is a major determinant of mortality. We report three cases of elderly patients with acromegaly aged 75, 70 and 66 years respectively with a literature review.Keywords: Acromegaly, aging population, pituitary surgery, prognosi

Analytical formulation of the fractal dimension of filtered stochastic signals

International audienceThe aim of this study was to investigate the effects of a linear filter on the regularity of a given stochastic process in terms of the fractal dimension. This general approach, described in a continuous time domain, is new and is characterized by its simplicity. The framework of this problem is general since it emerges when a fractal process undertakes a transformation, as is the case in denoising or measurement processes

La plaie cranio-cérébrale chez l’oxycéphale: quelle précaution prendre pour le traiter?

L'oxycéphalie isolée est une forme non syndromique des craniosténoses d'apparition tardive, elle est  responsable d'hypertension intracrânienne insidieuse pouvant aboutir, sinon traitée précocement, à la cécité et à la débilité mentale. En général méconnue, elle peut être révélée par tout phénomène pouvant  décompenser l'hypertension intracrânienne latente. Nous présentons un cas rare d'oxycéphalie révélée par un traumatisme crânien. Un jeune garçon de cinq ans s'est présenté avec une tuméfaction pariétale droite non réductible suite à une plaie cranio-cérébrale opérée à deux reprises à l'âge de trois ans puis six mois plus tard. Le bilan neuroradiologique a objectivé une hernie cérébrale avec empreintes digitiformes diffuses et une fusion des sutures crâniennes. Un bilan ophtalmologique a montré un strabisme convergent droit et un fond d'oeil normal. Une chirurgie d'expansion crâniennea été réalisée. L'évolution post-opératoire était favorable.  L'oxycéphalie harmonieuse peut passer inaperçue et un traumatisme crânien même bénin peut la révéler.Key words: Mots clé: Oxycéphalie, plaie cranio-cérébrale, craniosténose

From side streams to building blocks: gas phase conversion of biomass-derived feedstocks to valuable monomers

This thesis describes the chemical conversion of methyl levulinate (ML), a biorefinery side stream, to the valuable monomers methyl vinyl ketone (MVK) and methyl acrylate (MA). In the first part of the project, platinum 5 wt% on sulfided carbon was found to afford up to 18% yield of MVK from ML at 300°C. In the second part of the project, conversion of ML to methyl-3-acetoxypropanoate (M3AP) through a Baeyer-Villiger (BV) oxidation was studied. The thus-formed M3AP could be successfully converted to methyl acrylate (MA) in 97% yield via elimination of acetic acid in the gas phase at 600 °C.Diese Dissertation beschreibt die chemische Umwandlung von Methyllevulinat (ML) in die wertvollen Monomere Methylvinylketon (MVK) und Methylacrylat (MA). In dem ersten Teil des Projekts wurde festgestellt, dass 5 Gew .-% Platin auf sulfidiertem Kohlenstoff bis zu 18% MVK-Ausbeute aus ML bei 300 ° C liefern. In dem zweiten Teil des Projekts wurde die Umwandlung von ML in Methyl-3-acetoxypropanoat (M3AP) durch eine Baeyer-Villiger Oxidation untersucht. Das so gebildete M3AP konnte erfolgreich in 97% Ausbeute durch Eliminierung von Essigsäure in der Gasphase bei 600 °C in MA umgewandelt werden

Experimental investigations of quasi-flat acoustic absorbers enhanced by metamaterial layers

The efficiency of acoustic absorbers used for noise control can be improved by providing a smooth transition from the impedance of air to the impedance of the absorbing material in question. In the present work, such a smooth transition is materialised via application of gradient index metamaterial layers formed by quasi-periodic arrays of solid cylinders (tubes) with their external diameters gradually increasing from the external row of tubes facing the open air towards the internal row facing an absorbing porous layer. If acoustic wavelengths are much larger than the periodicity of the array, such a structure provides a gradual increase in the acoustic impedance towards the internal row of cylinders. This allows the developer to achieve an almost perfect impedance matching between the air and porous absorbing materials, such as sponges, fibreglass, etc. In the present work, a wide range of measurements of sound reflection coefficients from different absorbing materials combined with matching metamaterial layers formed by the arrays of brass tubes have been carried out at the frequency range of 500-3000 Hz. Both normal and oblique incidence of sound have been considered. The results show that the presence of matching metamaterial layers brings substantial reduction in sound reflection coefficients, thus increasing the efficiency of acoustic absorbers

Comparative Study of Amazigh Speech Recognition Systems Based on Different Toolkits and Approaches

The objective of this study is to evaluate and contrast the performance of different ASR approaches applied to the Amazigh language. Markovian modelling techniques, including Hidden Markov Models with Gaussian mixture distribution, Convolutional Neural Network, size of vocabulary, and lastly, the choice of decoder, whether Sphinx or HTK, by conducting a comprehensive analysis and comparison of these factors, this paper aims to provide valuable insights into the development of effective ASR systems for the Amazigh language. The findings will contribute to advancing the field of Amazigh ASR and aid in the selection of appropriate techniques and tools for future research and development efforts

Periodicity-enhanced structures for efficient sound absorption

In the present work, an overview of experimental investigations of the two types of periodicity-enhanced acoustic absorbing structures is given. In the first type of structures, the performance of acoustic absorbing materials is improved by providing a smooth transition from the impedance of air to the impedance of the absorbing material in question. This smooth change in the impedance is materialised using gradient index metamaterial layers formed by quasi-periodic arrays of solid cylinders. In the second type of performance improving devices, the principle of acoustic black holes has been implemented. To achieve the required power-law decrease in sound velocity with propagation distance the cylindrical inhomogeneous acoustic waveguides enhanced by quasi-periodic systems of concentric rings have been used. Measurements of the reflection coefficients for both types of structures have been carried out. The results show the possibility of substantial reduction of the acoustic reflections in both cases