Specific heat capacity and thermal conductivity of PEEK/Ag nanoparticles composites determined by Modulated-Temperature Differential Scanning Calorimetry

The thermal conductivity accurate measurement of polymer based composites is a challenge: it would allow us to understand the mechanisms of thermal transport in such materials. Silver nanoparticles were introduced in Polyetheretherketone matrix and their influence on thermal properties was studied. Thermal conductivity and specific heat capacity of composites were determined by Modulated-Temperature Differential Scanning Calorimetry and analysed as a function of particles volume content and temperature. The specific heat capacity of the composites decreases with increasing silver particles content below the electrical percolation threshold. Above the electrical percolation threshold the specific heat capacity decreases more slowly and converge toward the specific heat capacity of compressed silver nanoparticles. The evolution of the thermal conductivity with filler content exhibits a non-linear profile. Experimental data are coherent with the Maxwell model suggesting continuity of the polymer matrix and a contribution of the silver particles to the effective thermal conductivity greater than volume effect. The temperature dependence of the composites thermal conductivity is characteristic of amorphous phase, while a transition from vitreous-like to crystalline-like behaviour of the specific heat capacity is observed with the introduction of metallic particles

Polymerization study and rheological behavior of a RTM6 epoxy resin system during preprocessing step

Curing process and rheological behaviors of a monocomposant epoxy resin used in structural aeronautic applications are investigated. This study helped settle the basic parameters in order to optimize the infusion process of carbon fibers in an epoxy matrix. The effect of carbon nanotube dispersion during the preinjection step is also studied to improve electrical behavior of composite parts. The curing process has been analyzed at isothermal temperature using differential scanning calorimetry technique. Viscosity measurements were achieved with a Couette geometry, suitable for low viscosity resin. A shear-thinning effect caused by adding CNTs in the epoxy matrix is detected. It is more pronounced at high temperature for increasing CNT mass content

Grafted Human Embryonic Progenitors Expressing Neurogenin-2 Stimulate Axonal Sprouting and Improve Motor Recovery after Severe Spinal Cord Injury

7 p.Background: Spinal cord injury (SCI) is a widely spread pathology with currently no effective treatment for any symptom. Regenerative medicine through cell transplantation is a very attractive strategy and may be used in different non-exclusive ways to promote functional recovery. We investigated functional and structural outcomes after grafting human embryonic neural progenitors (hENPs) in spinal cord-lesioned rats.Methods and Principal Findings: With the objective of translation to clinics we have chosen a paradigm of delayed grafting, i.e., one week after lesion, in a severe model of spinal cord compression in adult rats. hENPs were either naive or engineered to express Neurogenin 2 (Ngn2). Moreover, we have compared integrating and non-integrating lentiviral vectors, since the latter present reduced risks of insertional mutagenesis. We show that transplantation of hENPs transduced to express Ngn2 fully restore weight support and improve functional motor recovery after severe spinal cord compression at thoracic level. This was correlated with partial restoration of serotonin innervations at lumbar level, and translocation of 5HT1A receptors to the plasma membrane of motoneurons. Since hENPs were not detectable 4 weeks after grafting, transitory expression of Ngn2 appears sufficient to achieve motor recovery and to permit axonal regeneration. Importantly, we also demonstrate that transplantation of naive hENPs is detrimental to functional recovery.Conclusions and Significance: Transplantation and short-term survival of Ngn2-expressing hENPs restore weight support after SCI and partially restore serotonin fibers density and 5HT1A receptor pattern caudal to the lesion. Moreover, grafting of naive-hENPs was found to worsen the outcome versus injured only animals, thus pointing to the possible detrimental effect of stem cell-based therapy per se in SCI. This is of major importance given the increasing number of clinical trials involving cell grafting developed for SCI patients.This study was supported by the European Union FP6 "RESCUE" STREP; the "Institut pour la Recherche sur la Moelle Epiniere"; the "Academie de Medecine"; the "Societe Francaise de Neurochirurgie"; "Verticale" and the "Association Demain Debout Aquitaine". The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Graft cell study in spinal cord injury model in the rat experimental surgery and molecular tools

Introduction : les lésions médullaires sont sources de déficits et souvent de handicap majeur. Afin de limiter les conséquences de ces traumatismes la recherche scientifique expérimente des stratégies thérapeutiques visant à  réduire la lésion et à   régénérer le tissu nerveux. Malheureusement la neuroprotection seule n'a jusqu'à  présent pu démontrer de réel bénéfice clinique et actuellement de nombreux espoirs reposent sur la neurorégénération via les thérapies cellulaires. Dans cet esprit nous avons développé et validé un modèle lésionnel chez le rat puis réalisé dans la lésion des greffes de cellules progénitrices embryonnaires humaines afin de promouvoir la régénération du tissu nerveux. Matériel et méthode : nous avons développé chez le rat un modèle de compression médullaire par inflation d'un ballonnet dans l'espace épidural en région thoracique (T9). Les animaux lésés présentent initialement une paraplégie sensitivo-motrice complète suivi d'une faible récupération neurologique spontanée (10%) à J7. Grâce à  ce modèle nous avons étudié les stratégies de régénération du tissu par la transplantation in situ dans la moelle lésée de cellules progénitrices. Des greffes de cellules progénitrices neurales embryonnaires ont ainsi été réalisées en région lésée ainsi que dans les métamères sus et sous jacents. Les cellules souches provenant d'embryons humains étaient préalablement transduites in vitro pour exprimer la Neurogénine 2. La Neurogénine 2 est un facteur neurotrophique permettant d'influencer la différenciation cellulaire en neurones.Résultats : le modèle de compression développé est fiable et reproductible. La validation pharmaceutique réalisée par l'administration d'une molécule neuroprotectrice: un antagoniste des récepteurs à  NMDA (Gacyclidine), confirme d'une part sa pertinence pour l'évaluation de stratégies thérapeutiques et d'autre part que l'excitotoxicité est un élément majeur des processus physiopathologiques survenant dans la phase secondaire de la lésion. Sur un suivi de 35 jours, les animaux greffés avec des cellules transduites pour exprimer la Neurogénine 2 présentent une récupération motrice significative. Cette récupération est corrélée à  la restauration partielle des fibres sérotoninergiques et de la localisation membranaire de leur récepteur en sous lésionnel. Les groupes contrôles et greffés uniquement avec des cellules souches non transduites n'atteignent pas, quant à eux, des scores efficaces et présentent une récupération fonctionnelle inférieure à celle des animaux non greffés. L'identification des cellules transplantées dans le tissu lésé grâce à des différents marquages (EGFP et HuNu) ne permet pas de retrouver ces cellules un mois après la transplantation.Conclusion : ces résultats sont encourageants et sont en faveur d'un bénéfice supporté par la greffe de cellules transduites pour exprimer la Neurogénine 2. Ces cellules sans survivre au delà  de un mois apporteraient un support trophique permettant une régénération et une récupération fonctionnelle. La restauration du système sérotoninergique dont on connaît l'implication dans la locomotion expliquerait ces résultats qui méritent cependant une validation sur un modèle gros animal (singe, porc) avant une application clinique.Spinal cord injuries (SCI) lead to deficits and often to major handicaps. To limit consequences of SCI, research focuses on the development of therapeutic strategies that aimed either at the reduction of the lesion and/or nervous tissues regeneration. Unfortunately, up to now the sole neuroprotective strategy did not demonstrate beneficial effects at the clinical level and there is thus more and more hopes based on neuroregenerative strategy in particular based on cell transplantation. In that aim, we have developed and characterized a rat injury model and grafted in the lesion site human embryonic progenitors to promote regeneration of nervous tissues.We have set up a rat model of spinal cord compression using an inflated balloon in the epidural space at the thoracic level (T9). Injured animals presented an initial complete sensory-motor paraplegia followed by a limited spontaneous neurological recovery (10%) one week after traumatism. Using this model, we have studied a regenerative strategy based on in situ progenitor cells transplantation in the injured spinal cord. Grafting of human embryonic progenitors had been done in the lesion site and in metamers located bellow and above the lesion. Human embryonic progenitors had been previously engineered in vitro to produce Neurogenin 2, a neurotrophic factor, that favours cell differentiation into neural lineages. The developed spinal cord compression model is reliable and reproducible. Pharmacological validation using a neuroprotective molecule, an antagonist of NMDA receptors (Gacyclidin), not only confirmed the pertinence of this model for the evaluation of therapeutic strategies but also that excitotoxicity plays a major role in the physiopathological processes involved in the secondary phase after lesion.Thirty five days after transplantation, rats that had been grafted with Neurogenin 2 expressing human embryonic progenitors demonstrated a significant motor recovery. This recovery was associated with a partial restoration of serotonin innervations bellow the lesion site and translocation of 5HT1A receptors to the plasma membrane of motoneurons. Animals transplanted with naïve cells presented a lower functional recovery than injured rat that had not been grafted. Moreover, one month after transplantation, grafted cells were not identifiable in the injured spinal cord. These encouraging results favour a beneficial effect of Neurogenin 2-expressing cells transplantation. One month after grafting, hENPs were undetectable in the injured spinal cord, thus functional recovery appears to be indirect and is likely due to trophic support supply. Partial restoration of serotonin innervations, whose role is well known in the locomotor function, may explain part of the observed functional recovery. These results clearly require to be validated in bigger animal models (monkey, pig) before any translation to the clinic

Les fractures traumatiques chirurgicales du rachis thoracique

Le rachis thoracique est un segment particulier de la colonne vertébrale du fait de ses particularités morphologiques et biomécaniques, et de ses rapports étroits avec l'axe neural. Les objectifs de la prise en charge des traumatismes de ce segment sont multiples: apporter une réduction, et une stabilisation immédiate et pérenne du rachis; protéger le système nerveux central et périphérique; l'ensemble en restant adapté aux contraintes spécifiques de cette région. Entre 2008 et 2010,68 patients sont opérés au CHU de Montpellier d'une ou plusieurs fractures du rachis thoracique. Nous avons étudié les caractéristiques cliniques et radiologiques de cette population. Nous avons analysé les traitements effectués, les complications, et les résultats fonctionnels, radiologiques et biomécaniques à 2 ans de suivi. La majorité des patients sont opérés par voie postérieure, avec un montage long comprenant en moyenne 5,3 vertèbres. Le délai médian d'intervention est de 2 jours et la durée médiane d'hospitalisation de 13 5 jours. Sur les instrumentations réalisées, près de 94% des crochets et 80% des vis sont considérés stables. Les valeurs moyennes de la réduction et de perte de correction sont semblables, d'environ 4,5. TI est retrouvé une supériorité des montages postérieurs longs ainsi que des vis pédiculaires pour la réduction et le maintien de la défonnation au terme du suivi. Les données fonctionnelles rapportent à l'issue du suivi une gêne quotidienne et des douleurs modérées. Cette étude rétrospective retrouve des résultats comparables aux données de la littérature. Une étude prospective analysant les différents types de procédures et d'instrumentations pennettrait de déterminer des guidelines de prise en charge.MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Les métastases rachidiennes dans le cancer du sein (Etat des lieux. Etude rétrospective sur 3 ans)

Introduction : Les cancers du sein sont parmi les cancers les plus ostéophiles. Les métastases rachidiennes sont parmi les plus fréquentes chez les patientes atteintes de ce cancer. Ces localisations entraînent une impoliante dégradation de la qualité de vie des patientes. Il est licite de potentialiser les différents traitements à visée antalgique, de réduction tumorale, de stabilisation de la statique rachidienne et de prévention neurologique. La réunion de concertation pluri-disciplinaire permet de coordonner et de rassembler les acteurs du traitement spécifique de cette pathologie. Matériels et méthodes: Cent quarante patientes, atteintes de cancer du sein avec métastases vertébrales, sont étudiées rétrospectivement. Différents paramètres sont examinés dont l'impact des traitements systémiques et spécifiques au rachis. Résultats: Une surveillance accrue des cancers du sein de haut grade semble essentielle à mettre en place: les métastases vertébrales apparaissent plus rapidement après le diagnostic de ca cer. La survie des patientes atteintes de cancer du sein avec métastases rachidiennes semble améliorée grâce à la combinaison coordonnée des différents traitements spécifiques au rachis. Une évolution des métastases vertébrales au caractère lytique vers un caractère mixte puis condensant est observée, corrélée aux traitements combinés tels que les bisphosphonates, la radiothérapie. Conclusion: La réunion de concertation multidisciplinaire - métastases osseuses - est essentielle afin de coordonner et potentialiser les différents acteurs (oncologues, radiothérapeutes, médecins nucléaires, radiologues interventionnels, chirurgiens du rachis), pour, in fine, favoriser une prise en charge optimale des patients présentant cet ensemble pathologique.Introduction: Breast cancers are one of the most osteophilic neoplasm, radio/chemosensitive with hormonal dependance. Spine metastasis contribute to decrease quality of life of patients. Medical actors must potentiate the different treatments available to decrease pain, to reduce tumor, to stabilise spine equilibrium and to prevent neurologie structures. Multidisciplinary meeting allow to coordinate and gather medical actors in order to pinpoint some specifie treatments of this pathology. Materials and Methods : One-hundred patients diagnosed for breast cancer with spine metastasis are studied retrospectively. Different parameters are studied. Effects of systemic and specific treatment targetting metastasis to the spine are analysed. Results : An increased attention must be done for breast cancer with high grade. Metastasis to the spine declare faster for this stages. Survival rate seems to be increased for the patients with spine metastatic events because of specifie treatment's association. An evolution of lytic spinal metastasis to mixt characteristic and then to blastic type is observed with combined therapy (bisphosphonates, radiotherapy). Conclusion: Multidisciplinary meeting, specialized in bone metastasis, is essential to coordinate and potentialize the different actors (oncologist, radiotherapist, nuclear medicine, interventional radiologist and spine surgeon)in order to ensure a complete and satisfactory follow-up of the patients.MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Anterior cervical spine surgical site infection and pharyngoesophageal perforation. Ten-year incidence in 1475 patients

International audienceBackground: Surgical site infection is reputed to be infrequent in anterior cervical spine surgery. Data on pathophysiological mechanism and risk factors are sparse. The relationship between local site infection and pharyngoesophageal perforation is unclear. The present study aimed: (1) to estimate the incidence of surgical site infection in anterior cervical spine surgery, (2) estimate the incidence of associated pharyngoesophageal perforation, and (3) suggest a decision-tree for early management of this twofold issue. Hypothesis: Although with very low incidence, anterior cervical spine surgical site infection and pharyn-goesophageal perforation are frequently associated. Material and methods: A 2-center retrospective study included all anterior cervical spine surgeries between January 1, 2007 and December 31, 2016. Data were provided by the two medical information departments. Patients undergoing anterior revision surgery on the cervical spine were included. Files were analyzed to determine whether the revision surgery was secondary to surgical site infection. Results: In total, 1475 patients with anterior cervical spine surgery were identified: 1180 in center A (80%) and 295 in center B (20%). The rate of revision surgery for surgical site infection was 0.34% (5/1475). There were 3 cases of pharyngoesophageal perforation (0.2%). Discussion: The incidence of revision surgery for anterior cervical spine surgical site infection was comparable to rates in the international literature (0.07-1.6%). An association between surgical site infection and pharyngoesophageal perforation was frequent, but not statistically significant. This complication is extremely serious, requiring urgent multidisciplinary management. Level of evidence: IV, retrospective study

Assessment of the Radiation Exposure of Surgeons and Patients During a Lumbar Microdiskectomy and a Cervical Microdiskectomy: A French Prospective Multicenter Study

International audienceOBJECTIVE:Cervical and lumbar disk herniations are the most frequently carried out procedures in spinal surgery. Often, a few snapshots during the procedure are necessary to validate the level or to position the implant. The objective of this study is to quantitatively estimate the radiation received by a spine surgeon and patient during a low-dose radiation procedure.METHODS:We conducted a prospective multicenter study in France from November 2014 to April 2015. Four spine centers were monitored for radiation received by surgeons during interventions for lumbar disk herniation and cervical disk herniation.RESULTS:A total of 134 patients were included. For lumbar disk herniation, the average exposure for the surgeon was 0.584 μSv on the chest, 5.291 μSv on the lens, and 9.295 μSv on the hands per procedure. For these procedures, the dose area product (DAP) was 94.2 ± 198.4 cGy·cm(2), and the fluoroscopic time was 10.2 ± 16.9 seconds. For a herniated cervical disk, the average exposure for the surgeon was 0.122 μSv on the chest, 3.106 μSv on the lens, and 7.143 μSv on the hands per procedure. For these procedures, the DAP was 35.7 ± 72.1 cGy·cm(2), and the fluoroscopic time was 19.7 ± 13.7 seconds.CONCLUSIONS:Exposure to x-rays for surgeons and patients during surgery for lumbar disk herniation is higher than during surgery for cervical herniation disk. Our results show that radiation exposure to the spine surgeon is still far below the annual dose limits

Potential adverse effects of cyclosporin A on kidneys after spinal cord injury

Study design:Cell transplantation strategies are gaining increasing interest for spinal cord injury (SCI) with the objective of promoting spinal cord repair. To avoid allogenic graft rejection, an adequate immune suppression is required, and one of the most potent and commonly used immunosuppressives is cyclosporin A (CsA). In SCI, permanent sensory motor loss is combined with modifications of drug absorption, distribution and elimination.Objectives:The objectives of this study were to thoroughly explore histological and functional outcomes of CsA treatment in a rat model of spinal cord compression.Setting: Experiments were carried out at the Institute for Neurosciences of Montpellier (France), the Integrative Biology of Neurodegeneration Laboratory (Spain) and in the Novartis Institutes for BioMedical Research (Switzerland) for CsA blood concentration determination.Methods:We first evaluated histological outcomes of CsA treatment on kidneys and spinal cord after SCI. We then investigated whether SCI modified CsA blood concentration. Finally, using behavioral analysis, we assessed the potential CsA impact on functional recovery.Results:When spinal-cord-injured rats were treated with a CsA dose of 10 mg kg -1 per day, we observed deleterious effects on kidneys, associated with modifications of CsA blood concentration. Adding an antibiotic treatment reduced kidney alteration without modifying CsA blood concentration. Finally, we showed that CsA treatment per se modified neither functional recovery nor lesion extension.Conclusion:This study pinpoints the absolute requirement of careful CsA monitoring in the clinical setting for patients with SCI to minimize potential unexpected effects and avoid therapeutic failure.Peer reviewe