Hélène Combrisson

The MRI assessment of intraurethrally - delivered muscle precursor cells using anionic magnetic nanoparticles

Autografting of cultured myogenic precursor cells (MPC) is a therapeutic strategy for muscle disorders, including striated urethral sphincter insufficiency. Implantation of myofibers with their satellite cells into the urethra is a recently described method of MPC transfer aimed at generating a new sphincter in incontinent patients. In this study, we magnetically labeled muscle implants with dextran-free anionic iron oxide nanoparticles (AMNP). The aim was to evaluate the biocompatibility of the labeling procedure and its utility for non-invasive MRI follow-up of cell therapy in a female pig model. After adsorption of AMNP to the implant surface, various cell types, including MPC, were magnetically labeled within the implants. Magnetic labeling did not affect cell proliferation or differentiation. Autograft detection in vivo by 0.3-T MRI was possible for up to 1 month. Ex vivo, Perls, anti-desmin and anti-myosin heavy chain staining confirmed the co-localization of AMNP and regenerated myofibers. AMNP labeling was thus useful for locating myofiber implant autografts in vivo and for ex vivo monitoring of the biology of this cell transfer method.

Pathology Influences Blood Pressure Change following Vagal Stimulation in an Animal Intubation Model

Purpose The haemodynamic response to critical care intubation is influenced by the use of sedation and relaxant drugs and the activation of the vagal reflex. It has been hypothesized that different disease states may have a contrasting effect on the cardiovascular response to vagal stimulation. Our objective was to determine whether the blood pressure response to vagal stimulation was modified by endotoxaemia or hypovolaemia. Methods New Zealand White rabbits were anaesthetised with urethane before tracheotomy. The exposed left Vagus nerve of randomised groups of control (n = 11), endotoxin (n = 11, 1 mg/kg), hypovolaemia 40% (n = 8) and hypovolaemia 20% (n = 8) rabbits were subjected to 10 Hz pulsed electrical stimulations of 25 s duration every 15 min. Haemodynamic parameters were recorded from a catheter in the right carotid artery connected to an iWorx monitor. Serum catecholamines were measured every 30 min using reverse-phase ion-pairing liquid chromatography. The change in blood pressure after vagal stimulation was compared to controls for one hour after the first death in the experimental groups. Results 29% of the rabbits died in the hypovolaemia 40% group and 27% in the endotoxin group. One rabbit died in the hypovolaemia 40% group before vagal stimulation and was excluded. Following electrical stimulation of the Vagus nerve there was a fall in blood pressure in control rabbits. Blood pressure was conserved in the hypovolaemic rabbits compared to controls (p<0.01). For the endotoxaemic rabbits, there was a non-significant trend for the mean blood pressure to decrease more than the controls. Serum catecholamines were significantly raised in both the hypovolaemic and endotoxaemic rabbits. Conclusions Pathology may contribute to modifications in blood pressure when vagal activation occurs. Patients who are either already vasoconstricted, or not vasoplegic, may be less at risk from intubation-related vagally mediated reductions in blood pressure than those with vasodilatory pathologies.

LA DIRECTIVE 2010/63/UE: L’EXPLICITE ET L’IMPLICITE

On september 2010, a new European Directive for the protection of vertebrate animals used for experimental purposes was signed. It replaces the previous 1986 Directive and represents a significative change in increasing substantially the protection of experimental animals. The changes concern mainly the domain of application, the structure and the management of the animal facilities either breeding colonies or research laboratories. The whole staff should acquire qualifications more finely tuned to their duties. The authorization of projects based on their ethical value is now under control of an administrative process. These modifications impact on ways of functioning in all the establishments with for objective a better consideration of 3R (Reduction, Refinement Replacement) to the advantage of animals. However, their implementation is not always easy to do ; it is essential to find the good compromises to increase the standards of animal protection while protecting the possibility of pursuing a high quality experimental research in Europe

Effects of Metoclopramide on Urethral Pressure Profile of Healthy Dogs

PURPOSE The purpose of the present work was to study the effect of metoclopramide on urethral pressure since urethral relaxation is an important factor in vesical voiding. MATERIALS AND METHODS Urethral pressure was measured in 6 dogs, anesthetized with propofol before and 1, 5 and 10 minutes after the administration of metoclopramide (0.5 mg/kg.) or placebo. RESULTS A single injection of metoclopramide induced a large decrease in maximal urethral closure pressure (53 to 90%; mean 71%, p < 0.001--Anova). The decrease with placebo, 5 to 44% (mean 26%), was not significant (Anova test: p = 0.06). CONCLUSION It is argued that a central dopaminergic action most probably accounts for this effect of metoclopramide on urethral pressure.

Mise au point d’un modèle anatomique d’insuffisance sphinctérienne urétrale chez la truie pour l’évaluation de nouvelles stratégies thérapeutiques

Introduction de nouveaux traitements sont en cours d’investigation pour l’insuffisance sphincterienne uretrale. Cependant, il n’existe pas de modele animal permettant d’evaluer precisement l’implication du sphincter strie dans le tonus uretral. Nous avons decrit les caracteristiques anatomiques du sphincter strie uretral (SSU) de la truie et evalue son role dans la continence urinaire. Materiel et methode le SSU de 10 truies a ete decrit par voie chirurgicale et endoscopique. La participation du SUS dans le tonus uretral a ete evaluee par mesure de la pression de cloture (PC) avant/apres injection de curare ou 1 mois apres lesion endoscopique. Les uretres ont ete etudies en immunohistologie (anticorps anti MyHC type I ou II) avec reconstruction 3D. Resultats le SSU avait une forme en Omega et entourait le tiers distal de l’uretre. Il etait compose de 52 %/48 % de fibres de type I/II. Le profil uretral presentait un pic de pression distal correspondant a localisation anatomique du SUS. L’injection de curare ou la destruction endoscopique selective du sphincter abolissait le pic de pression distal uretral et diminuait la PC de respectivement 48 % et 41 %. Une heure apres injection de curare, la PC revenait a la normale. Conclusion le SSU de la truie presente des caracteristiques morphologiques et fonctionnelles proches de celui de l’homme. Notre etude morphologique et fonctionnelle a permis de demontrer et de quantifier le role du SSU dans la tonicite uretrale chez la truie. Ces resultats apportent des outils pour l’evaluation de toute nouvelle therapie de l’insuffisance sphincterienne visant a augmenter le tonus uretral.