The phenotypic and molecular analysis of the production of broad-spectrum beta lactamases (ESBLs) among strains of Escherichia coli isolated from food in Hamedan

Introduction One of the reasons for drug resistance in Escherichiacoli isolates is the production of broad-spectrum beta-lactamases. The widespread use of antibiotics in the agricultural and dairy industry has led to raisingin antibiotic resistance. Therefore, the aim of this study was to investigate the phenotypic and molecular ESBLs production among E. coli isolated from food. Materials and Methods This descriptive cross-sectional study was carried out by 93 E. coli isolated from food and poultry in Hamadan in 2017. Then, the microbial susceptibility of the beta-lactamase producing isolates was determined using the (Combined teat CT) method and according to CLSI (2015) guidelines. Also, molecular identification of genes producing ESBLs (blaSHV, blaCTX-1, and blaTEM-1) was performed by PCR method. Results Evaluation of microbial susceptibility showed that the highest antibiotic resistance was observed for nalidixic acid (%88.4), ampicillin (%76.8), tetracycline (%82.8), and sulfomethoxazole (%67). Resistance to ceftazidime, Cefoxitin, aztreonam, cefotaxime was not observed in this study. The genotypic study by PCR method showed that the frequency of blaSHV, blaCTX-1, and blaTEM-1genes in E. coli isolated from food (%5.37), (%19.35) and (%29.03), respectively. Conclusion E.coli isolated from food showed high resistance to antibiotics such as ampicillin, sulfomethoxazole, and tetracycline. On the other hand, the PCR method is more sensitive than the culture method

Mechanics of gelatin-based hydrogels during finite strain tension, compression and shear

International audienceIntroduction: Among the biopolymers used to make hydrogels, gelatin is very attractive due to its biocompatibility, biodegradability and versatile physicochemical properties. A proper and complete characterization of the mechanical behavior of these hydrogels is critical to evaluate the relevance of one formulation over another for a targeted application, and to optimise their processing route accordingly.Methods: In this work, we manufactured neat gelatin and gelatin covalently crosslinked with glutaraldehyde at various concentrations, yielding to hydrogels with tunable mechanical properties that we characterized under finite strain, cyclic tension, compression and shear loadings.Results and Discussion: The role of both the chemical formulation and the kinematical path on the mechanical performances of the gels is highlighted. As an opening towards biomedical applications, the properties of the gels are confronted to those of native soft tissues particularly complicated to restore, the human vocal folds. A specific cross-linked hydrogel is selected to mimic vocal-fold fibrous tissues

Développement d’un avatar mécatronique pour produire de la voix, de la parole et du chant

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Towards a biomimetic mechatronic testbed for voice and speech

International audienceTo reproduce phonation in vitro, vocal-fold testbeds have been refined over the last thirty years, gaining in complexity and biomimicry. However, most testbeds explore the physics of phonation on geometrically-fixed replicas capable of self-sustained oscillations in fluid-structure interaction. These testbeds are not necessarily coupled to vocal-tract cavities. Where they are, testbeds rarely allow for movement of the articulators of speech, such as the jaw, tongue, velum and larynx. They usually rely on 3D-printed vocal tracts to reproduce a resonant cavity linked to a fixed vocal configuration scanned by CT or MRI. This project aims to design a complete testbed that would integrate all phonatory and articulatory aspects important for voice and speech production. Such a mechatronic testbed is under development. It consists of a silicone laryngeal envelope, a 1:1 scale vocal-fold replica coupled with a geometrically-realistic vocal tract. The vocal fold replica can be adducted/abducted, stretched into the antero-posterior direction and compressed into the lateral direction. They can self-oscillate over a wide range of flow rates and for different degrees of tensile stretch. Glottal vibratory behaviour was assessed for single-and bilayered vocal-fold replicas, for different layer stiffnesses, for homogeneous and fibre-reinforced layers. The vocal tract can reproduce several primary articulatory gestures : mandibular motion and shaping of the oral cavity with the movement of the tongue body. The applications of such testbed will be discussed

Design of fibre-reinforced biomaterials based on novel hydrogels to mimic the vocal folds properties

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On the development of new composite hydrogels mimicking vocal-fold histological and mechanical features

International audienc

Multi-axial mechanical properties of hydrogel-based materials upon finite strains: towards the design of tailored vocal-fold composite replicas

International audienceIn vitro modeling of phonation requires materials able to mimic the vibro-mechanical features of vocal-fold tissues:ability to (i) endure large deformations under physiological multiaxial loadings and strain rates], (ii) adapt their vibromechanical behavior to external loadings and environmental changes. Among relevant candidates, hydrogels are attractive materials due to their tissue-like water content. However, the mechanical characterization of hydrogels is often limited to single monotonic loadings, mainly in compression, or to standard DMA analyses. These configurations are far from those endured by the tissue in vivo. Here, we manufactured hydrogels with tunable mechanical properties that we characterized under realistic, finite strain, cyclic tension, compression and shear loadings

Flow-induced oscillations of vocal-fold replicas with tuned extensibility and material properties

Abstract Human vocal folds are highly deformable non-linear oscillators. During phonation, they stretch up to 50% under the complex action of laryngeal muscles. Exploring the fluid/structure/acoustic interactions on a human-scale replica to study the role of the laryngeal muscles remains a challenge. For that purpose, we designed a novel in vitro testbed to control vocal-folds pre-phonatory deformation. The testbed was used to study the vibration and the sound production of vocal-fold replicas made of (i) silicone elastomers commonly used in voice research and (ii) a gelatin-based hydrogel we recently optimized to approximate the mechanics of vocal folds during finite strains under tension, compression and shear loadings. The geometrical and mechanical parameters measured during the experiments emphasized the effect of the vocal-fold material and pre-stretch on the vibration patterns and sounds. In particular, increasing the material stiffness increases glottal flow resistance, subglottal pressure required to sustain oscillations and vibratory fundamental frequency. In addition, although the hydrogel vocal folds only oscillate at low frequencies (close to 60 Hz), the subglottal pressure they require for that purpose is realistic (within the range 0.5–2 kPa), as well as their glottal opening and contact during a vibration cycle. The results also evidence the effect of adhesion forces on vibration and sound production

Développement d’un banc in vitro pour la caractérisation vibratoire de plis vocaux biomimétiques et pré-déformés

International audienceIn order to make progress on physical understanding of speech, a testbed was developed. It currently allows to study the vibromechanical behaviour of extensible isotropic vocal folds in fluid-structure interaction. This article describes the different components of the testbed and presents the first results obtained on homogeneous and isotropic folds. The larynx replica consists of a deformable siliconerubber envelope into which expandable vocal fold replicas can be inserted for testing. The material and structural properties of the folds are adjustable. Three silicone-rubber with various stiffnesses were tested, as well as a cross-linked hydrogel. The self-oscillation of the pleats is controlled by the upstream air flow. The tested folds self-oscillated over a wide range of flow rates and for various degrees of stretching.Pour avancer sur la compréhension physique de la parole, un banc de test a été élaboré dans une approche biomimétique. Il permet actuellement d’étudier le comportement vibromécanique de plis vocaux extensibles et isotropes en interaction fluide-structure. Cet article décrit les différents constituants du banc test et présente les premiers résultats obtenus sur des plis homogènes et isotropes. La réplique du larynx consiste en une enveloppe en silicone déformable dans laquelle des répliques de plis vocaux extensibles peuvent être insérées pour être testées. Le matériau et les propriétés structurelles des plis sont ajustables. Trois silicone-élastomères de rigidité différentes ont été testés, ainsi qu’un hydrogel réticulé. L’auto-oscillation des plis est contrôlée par le débit d’air en amont. Les plis testés ont auto-oscillé sur une large gamme de débits et pour divers degrés d’étirement