Objectifs : Etudier le développement osseux de l'oreille interne chez le foetus humain. Matériel et Méthode : Notre institution dispose d'une banque de foetus humains qui ont été étudiés par tomodensitométrie. Les images ont été exploitées grâce au logiciel Amira . 13 dimensions cochléo-vestibulaires standards ont été mesurées chez 153 foetus. L'angulation entre les 3 canaux semi-circulaires (CSC) et le positionnement du vestibule ont été étudiés chez 54 foetus. L'analyse statistique a été réalisée grâce au logiciel R. Résultats : Il n'y a pas de dimorphisme sexuel, ni de différence droite-gauche dans les distances mesurées. 8 mesures cochléo-vestibulaires n'évoluent pas en taille de 21 à 40 SA. L'îlot osseux du CSC latéral croît jusqu'à 25 SA. L'aqueduc de la cochlée et le conduit auditif interne sont corrélés à l'âge foetal. L'angle entre les CSC est proche de 90°, malgré de larges écarts physiologiques, et n'évolue pas entre 21 et 40 SA. Il n'y a pas de dimorphisme sexuel. Le centre du vestibule est stable dans son positionnement anatomique au sein du rocher pendant le développement foetal. Conclusion : Conformément aux données de la littérature, la croissance cochléo-vestibulaire se termine à 21 SA ou moins. Certains éléments de l'oreille interne croissent avec l'os pétreux et évoluent avec l'ossification du rocher. La stabilité du positionnement du vestibule dans le rocher évoque une détermination génétique forte. Notre série est quantitativement la plus importante jamais publiée dans la littérature / Objectives: Our goal is to clarify the course of inner ear bony development in human fetuses. Material and Methods: Our institution hosts a collection of human fetuses from 21 to 40 WA that were CT scanned and studied with Amira(tm) software. We studied 13 measurements in the inner ear of 153 fetuses. We also studied semi-circular canals orientation and the vestibular ear positioning in petrous bone of 54 human fetuses. Statistical analysis was performed with R(tm) software. Results: We found no side-related differences or sexual dimorphism. 8 cochlear and vestibular bone measurements did not show growth from 21 to 40 WA and are similar to those of adults in literature. The lateral semicircular canal bony island grows until 25 WA. Internal auditory canal and cochlear aqueduct growth are correlated with gestational age. Mean angles between the three semi-circular canals are close to orthogonality, despite important physiologic variations, and did not change significantly from 21 to 40 WA. There was no sexual dimorphism. The center of vestibular ear has a stable positioning within the three angles of petrous bone during fetal gestation. Conclusions: In accordance with literature, we confirm that the cochlea and semi-circular canals 3D configuration reaches their adult size at or before 21 WA. Some parts of the inner ear (cochlear aqueduct, IAC) continue to grow with petrous bone and evolve with its ossification. To the best of our knowledge, our series is the largest series of human fetal inner ear ever published.

Exposure to abnormal motion produces a variety of behavioural effects in both human and non-human species. The general purpose of the present studies was to produce and investigate some of these effects in the laboratory rat. In the first series of experiments, rats displayed appreciable decreases in reactivity to noxious stimuli presented after exposure to brief periods of different types of motion. This motion-induced antinociception was found to persist for periods of up to 15 min. A second series of experiments examined the role of the vestibular system in this motion-induced antinociception phenomenon. Rats whose peripheral vestibular apparatus had been rendered insensitive to accelerative stimuli did not exhibit motion-induced antinociception. Subsequent experiments attempted to delineate the role of some individual components of the central vestibular system but no single component investigated was found to play a major role in the production of antinociception. Experiments in this and the preceding series of experiments also demonstrated that the antinociceptive effect could be dissociated from dizziness or acute vestibular dysfunction. In the third series of experiments, the physiological mechanisms by which vestibular stimulation produces antinociception were investigated. Experiments in this series demonstrated that motion-induced antinociception could be blocked by opiate antagonists and that the motion-induced antinociceptive effect showed cross-tolerance with chronic morphine administration. These two findings strongly implicate an endogenous opiate peptide (endorphin) system as the underlying mechanism for mot ion-induced antinociception. The brief duration of the antinociceptive effect and the fact that disruption of the pituitary-adrenal axis did not affect motion-induced antinociception suggested that the opiate peptides involved were the enkephalins rather than B-endorphin. Other behavioural effects of abnormal motion were reported in the the fourth series of experiments. The resemblance between the symptoms of motion sickness and those of opiate administration suggested that endogenous opiate peptides may mediate motion sickness. Although exposure to abnormal motion did produce a substantial conditioned taste aversion (a behavioural assay for motion sickness in the rat), attempts to attenuate the aversion with two different opiate antagonists were unsuccessful. These results suggested that abnormal motion exerts its illness-producing effects through some mechanism other than an endogenous opiate system. In the final experiment, rats that were exposed to a brief period of abnormal motion subsequently exhibited a suppression of defensive burying behaviour that was similar to that produced by anxiolytic drugs. The results of this study indicate that abnormal vestibular stimulation may have a variety of different behavioural effects in rats. However, it appears that no single mechanism can account for all of these effects. / Arts, Faculty of / Psychology, Department of / Graduate

Les connexions entre les cellules sensorielles et les neurones primaires de l’oreille interne, appelées synapses sont essentielles à l’encodage et la transmission des informations auditives et vestibulaires vers le cerveau. C’est aussi une zone extrêmement exposée et fragile qui semble impliquée dans de nombreuses atteintes de l’audition et de l’équilibration, mais également au cours du vieillissement. Des récupérations spontanées de l’audition et de l’équilibre ont été observées suite à ces différentes atteintes chez l’Homme. Dans le cadre de ma thèse, j’ai étudié d’une part, comment des atteintes sélectives de ces synapses pouvaient générer des troubles de l’oreille interne chez l’animal, et d’autre part, comment des mécanismes de réparation spontanée de ces synapses supportent la récupération des fonctions auditives et vestibulaires. Nous avons constaté qu’il existe une hétérogénéité dans les capacités de réparations synaptiques entre la cochlée et le vestibule. L’étude des mécanismes moléculaires mis en jeu dans cette réparation synaptique pourrait ouvrir la voie au développement de nouvelles stratégies thérapeutiques pour les atteintes de l’oreille interne. / Inner ear connections between primary neurons and sensory cells, called synapses are essential for encoding and transmitting auditory and vestibular information to the brain. It is also an extremely exposed and fragile area that is involved in many hearing and balance disorders, but also during aging. Spontaneous hearing and balance recoveries have been observed following these different injuries in humans. In the context of my thesis, I studied, on the one hand, how selective lesions of these synapses could generate inner ear disorders in animals, and on the other hand, how spontaneous repair mechanisms of these synapses support auditory and vestibular functions recovery. We found that there is heterogeneity in synaptic repair capabilities between the cochlea and the vestibule. The study of the molecular mechanisms involved in this synaptic repair could pave the way for the development of new therapeutic strategies against various inner ear disorders.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.

La scoliose idiopathique de l’adolescent est caractérisée par une déformation en trois dimensions de la colonne vertébrale. Les causes qui expliquent l'apparition de la scoliose demeurent encore aujourd’hui incertaines, ce qui suggère que l’étiologie de la pathologie est d’ordre multifactoriel. (Lowe et al., 2000). Il a été démontré que les patients atteints de la scoliose idiopathique voient leur contrôle postural affecté lorsque leurs informations sensorielles sont manipulées (Simoneau et al., 2006). Le but de cette étude était d’évaluer si les patients atteints de scoliose idiopathique utilisent davantage les informations vestibulaires que les informations proprioceptives pour contrôler leur équilibre. La stimulation galvanique vestibulaire a été utilisée afin d’engendrer une réponse vestibulomotrice lors de trois conditions : debout, assis stable et assis instable. De plus, la morphologie de l'appareil vestibulaire de 5 patients scoliotiques et 6 individus sains a été mesurée par la technique d’imagerie par résonnance magnétique. Les présents résultats démontrent que certains patients atteints d’une scoliose idiopathique intègrent moins efficacement les informations vestibulaires et proprioceptives du tronc et des membres inférieurs.

Diss. Linköping : Univ., 2003. / Härtill 4 uppsatser.

L'homéostasie glutamatergique dans les fentes synaptiques régule la neurotransmission et préserve de l'excitotoxicité. Cela est particulièrement important dans l'oreille interne où il y a une libération soutenue de neurotransmetteur. Pour la plupart des cellules ciliées cochléaires et vestibulaires, la clairance du glutamate est assurée par les transporteurs du glutamate EAAT1 (GLAST) exprimés par les cellules de soutien. Un tel mécanisme n'est pas possible pour les cellules ciliées vestibulaires de type I car leur terminaison synaptique en calice empêche tout accès à la fente synaptique. Nous avons donc postulé qu'un ou plusieurs transporteurs du glutamate devaient être présents au niveau des cellules ciliées de type I ou du calice ou des deux.Grâce à des enregistrements électrophysiologiques, nous avons démontré qu'un courant anionique induit par le glutamate et bloqué par le DL-TBOA est présent dans les cellules ciliées de type I. Les techniques d'hybridation in situ et d'immunohistochimie ont révélé la présence d'EAAT4 et EAAT5. Ces deux transporteurs du glutamate, qui pourraient êtres à l'origine des courants enregistrés, sont exprimés par les cellules ciliées de type I et de type II. De plus, des expériences de RT-PCR et de microscopie électronique ont confirmé ces résultats et suggéré que ces transporteurs pourraient aussi être exprimés postsynaptiquement par le calice. Ces travaux de thèse montrent qu'EAAT4 et EAAT5, considérés respectivement comme spécifiques des tissus cérébelleux et rétiniens, ont une distribution plus large. Ces résultats posent la question des rôles potentiels de ces transporteurs dans l'homéostasie glutamatergique vestibulaire. / Glutamate homeostasis in synaptic clefts shape neurotransmission and prevent excitotoxicity. This may be particularly important in the inner ear where there is a continually high rate of neurotransmitter release. In the case of most cochlear and vestibular hair cells, clearance involves the diffusion of glutamate to supporting cells, where it is taken up by EAAT1 (GLAST), a glial glutamate transporter. A similar mechanism is unlikely to work in vestibular type I hair cells because the presence of calyx endings separates supporting cells from the synaptic zone. Based on this arrangement, we postulated that a glutamate transporter must be present in the type I hair cell, the calyx ending, or both. Using whole-cell patch-clamp recordings, we demonstrated that a glutamate-activated anion current blocked by DL-TBOA is expressed in type I hair cells. In situ hybridization and immunohistochemistry revealed that EAAT4 and EAAT5, two glutamate transporters that could support the anion current, are expressed in both type I and type II hair cells. Furthermore, RT-PCR and immunogold investigations confirmed those results and added that although preferentially expressed presynaptically, the transporters may also be present in the postsynaptic calyx membrane. Previously thought to be exclusively expressed in the cerebellum and retina respectively, this thesis work shows that EAAT4 and EAAT5 have a wider distribution. The potential role of these transporters in the glutamatergic homeostasis of the calyx synapse is then discussed.

Les cellules ciliées internes (CCIs) de la cochlée encodent les signaux acoustiques en impulsions électriques au niveau des synapses à ruban formées avec les fibres afférentes du nerf auditif. L'exocytose des vésicules glutamatergiques par les CCIs est déclenchée par l'activation des canaux calciques Cav1.3 et par l'otoferline, le senseur calcique intracellulaire présumé. Les mécanismes moléculaires précis régulant cette exocytose restent encore mal compris, notamment ceux à l’origine de sa précision temporelle, sa vitesse élevée en phase avec le signal acoustique("phase-locking" jusqu'à 1-2 kHz) et son infatigabilité. Nous montrons que la spécificité des synapses à ruban auditive et vestibulaire passe par une organisation spatiale spécifique des canaux Cav1.3 dans les zones actives. Les CCIs utilisent différentes isoformes de canaux Cav1.3, notamment des isoformes courtes tronquées dans leur partie C-terminale. Ces isoformes courtes (Cav1.343S et Cav1.342A) sont essentiellement impliquées dans le déclenchement et dans l'adaptation rapide de l'exocytose. Cette adaptation se réalise au niveau des canaux Cav1.3 à la fois en intracellulaire par le Ca2+ et en extracellulaire parles protons secrétés lors de l'exocytose. Les isoformes longues (Cav1.342L et Cav1.3∆44),positionnées en périphérie du ruban, réguleraient le recrutement vésiculaire. Par ailleurs, nous montrons que l'organisation spatiale des canaux Cav1.3 est dépendante d'un cytosquelette d'actine-F au ruban synaptique. La clarine 1 (protéine Usher IIIA) interagirait avec l'actine-F, l'harmonine (protéine PDZ, Usher IC) et la sous-unité β2 des canaux calciques pour organiser les canaux Cav1.3 dans les zones actives. / Cochlear inner hair cells (IHCs) encode acoustic signals into nerve impulses at their ribbon synapses formed with the auditory afferent fibers. The exocytosis of glutamatergic vesicles is triggered by voltage activation of Cav1.3 channels and requires otoferlin, the putative intracellular Ca2+ sensor. The precise molecular mechanisms of exocytosis still remain elusive, notably the mechanisms allowing the temporal precision, the high rates of vesicular fusion (high frequency phase-locking with sound) and the indefatigability of the process. We show here that exocytosis in auditory and vestibular hair cells relies on a specific tight spatial organization of Cav1.3 channels at the active zones. Auditory IHCs use different Cav1.3isoforms, notably short C-terminal isoforms (Cav1.343S et Cav1.342A). These short Cav1.3isoforms essentially trigger the RRP exocytosis (Readily Releasable Pool of vesicles) and are at the origin of its fast adaptation. This fast exocytotic adaptation is based both on an intracellularCa2+ dependant inactivation of the Ca2+ current and on its extracellular block by exocytosed protons. Long Cav1.3 isoforms (Cav1.342L et Cav1.3∆44) regulate the vesicular recruitment at the active zones. Furthermore, our results show that a synaptic actin cytoskeleton is essential for the tight spatial organization of the Cav1.3 channels at the ribbons. Clarin 1 (Usher IIIA protein),through its interactions with the F-actin network, harmonin (PDZ protein, Usher IC) and the Ca2+channel β2 subunit, is required to maintain the tight organization of Cav1.3 channels at the ribbon synapses.

4 Abstract Purinergic P2X receptors are membrane ion channels activated by extracellular ATP. There are seven isoforms of mammalian P2X receptors designated as P2X1-7, which according to their structure represent a specific family of ligand gated ionic channels, with extraordinary structural/functional properties. The P2X receptor consists of three subunits and each subunit has two transmembrane domains. Crystalographic data demonstrate that ionic channel pore is situated between the second transmembrane domains. Crystal structure of P2X4 receptor from the zebrafish (Danio rerio) is available in both open and closed state of the channel and the exact structure of ATP binding site is solved. The aim of this thesis was to study the structure-function relationships in a model of recombinant P2X4 receptor of the rat. By employing the point mutagenesis and electrophysiological recording, the functional importance of conserved cysteine residues in the ectodomain and amino acid residues which form the extracellular vestibule was investigated. All ten cysteins were substituted one by one with alanine or threonine and ATP-induced currents were measured from HEK293T cells expressing wild type (WT) and mutated P2X4 receptors. The results indicate that C116A, C126A, C149A and C165A mutations disrupt two disulfide bonds...

Objetivos: analisar a associação entre otite média crônica não colesteatomatosa (OMCNC) e os resultados obtidos no video head impulse test (vHIT). Delineamento: tipo transversal. Métodos: a amostra foi selecionada em ambulatório especializado de um hospital universitário. A inclusão dos pacientes neste estudo obedeceu aos seguintes critérios: idade entre 7 e 59 anos; diagnóstico de OMCNC unilateral, com orelha contralateral normal; não ter realizado cirurgia otológica prévia; não ter comprometimentos cognitivos e/ou neurológicos e/ou motores registrados nos prontuários. Os critérios de exclusão foram: impossibilidade de retirada de maquiagem nos olhos (impossibilita a execução do exame); não compreensão ou dificuldade na execução das ordens do exame. Os pacientes foram divididos em Grupo A (7 a 19 anos) e Grupo B (20 a 59 anos). Todos foram avaliados por meio de exame otorrinolaringológico padrão do ambulatório, anamnese e vHIT. Os exames com valor de ganho superior a 0,8 foram considerados normais. Os canais com valores de ganho entre 0,6 e 0,8 foram classificados, nesta pesquisa, como limítrofe. Nos casos considerados limítrofes, foi analisado o valor da assimetria para diagnóstico, que foi considerada anormal acima de 20%. Para o cálculo amostral evidenciou que o número mínimo de indivíduos avaliados seria de, 10 sujeitos no grupo A e 20 sujeitos no grupo B. Resultados: a amostra total foi composta por 32 indivíduos. O grupo A foi formado por 11 indivíduos, com idade média de 12,7 ± 3,9 anos e o grupo B por 21 indivíduos, com idade média de 46,3 ± 11,1 anos. A análise dos resultados do vHIT revelou que não houve diferença significativa entre o lado considerado normal e o lado considerado afetado, considerando-se a análise intragrupo e entre grupos. Conclusão: a pesquisa evidenciou que, na amostra estudada, não houve diferença nos resultados obtidos no vHIT entre os lados afetados e não afetados pela OMCNC. / Objectives: To analyze the association between chronic otitis media (COM) without cholesteatoma and results in the video head impulse test (vHIT). Design: Cross sectional. Methods: The sample was selected in a specialized clinic of a university hospital. Patient inclusion in this study obeyed the following criteria: age between 7 and 59 years; diagnosis of unilateral COM without cholesteatoma with normal contralateral ear; not having done previous ear surgery; not having cognitive impairment and / or neurological and / or motor recorded in the medical records. The exclusion criteria were: patients with eye makeup, which cannot be removed (makes it impossible to perform the exam); patients who did not understand the operation of the test and therefore could not accomplish it. Patients were divided in group A (7 to 19) and group B (20 to 59) years of age. Both groups performed standard outpatient otolaryngology evaluation, clinical history and video head impulse test. Exams with a gain above 0.8 were considered normal. Canals gain values between 0.6 and 0.8 were classified in this study as borderline. In borderline cases considered, we analyzed the value of asymmetry for diagnosis, which was considered abnormal over 20%. For sample size calculation showed that the minimum number of individuals assessed was of 10 subjects in group A and 20 subjects in group B. Results: The total sample consisted of 32 individuals. Group A consisted of 11 subjects mean with an average age of 12.7 ± 3.9 years and the group B of 21 subjects with an average age of 46.3 ± 11.1 years. Analysis of the vHIT results showed no significant difference between the side considered normal and the side considered affected, considering the intra-group and between groups analysis. Conclusion: The research showed that, in our sample, there was no difference in the results obtained in vHIT between the affected side and the not affected by COM without cholesteatoma.