Дисертації з теми "Dentine – Physiologie"

Introduction : en médecine légale, l'identification des restes humains est un problème récurrent. L'estimation de l'âge au décès est l'un des critères à évaluer. Chez les adultes, la hauteur de la transparence de la dentine radiculaire est utilisée. Cependant, dans le matériel archéologique, ce phénomène apparaît inconstant et en lien avec des modifications d'aspect de la dentine sclérotique. Le but de ce travail était d'observer les modifications de la dentine sclérotique à différents délais post-mortem en se concentrant sur la partie minérale qui est le composant principal de ce tissu et qui est susceptible d'avoir des variations plus marquées sur des délais post-mortem longs. Matériel et Méthode : l'étude comprenait deux parties (rétrospective et prospective) avec 21 dents humaines monoradiculées, trois datées du 18ème siècle provenant de fouilles archéologiques et dix-huit issues de dons du corps à la science de la Faculté de médecine de l'Université de Lille conservées dans des conditions équivalentes et analysées à différents délais post-mortem de 0, 1, 2 et 5 ans. Après inclusion en résine, les dents ont été sectionnées et polies, puis analysées au microscope électronique à balayage, complétés par une analyse semi-quantitative du calcium et du phosphore par microanalyse EDS-X, ainsi qu'une détection large d'éléments du tableau périodique. Dans un second temps nous avons réalisé une analyse cristallographique par diffractométrie en rayons X.Résultats : les analyses ont montré l'existence de modifications tubulaires, chimiques et cristallographiques de la dentine sclérotique en fonction du délai post-mortem. Notre étude au microscope électronique à balayage nous a permis d'observer une différence d'aspect des tubules en lien avec l'augmentation du délai post-mortem : perte du col péritubulaire et obstruction de la lumière des tubules par un matériau hyperdense. La microanalyse a mis en évidence des variations des rapports phosphocalciques entre les différents groupes, notamment au niveau de la jonction avec le cément et plus spécifiquement dans la canine qui pourrait être un bon modèle prédictif pour l'évaluation du délai post-mortem. Par diffractométrie, nous avons confirmé que la phase minérale de la dentine sclérotique, quel que soit le délai post mortem, était composée de cristaux d'hydroxyapatite, avec un meilleur niveau de cristallinité dans les dents archéologiques par rapport aux dents de délai post-mortem 5 ans, mais aussi entre les dents de délai post-mortem de 0 et 1 an, par rapport à 2 ans. Discussion : les différences observées pourraient reposer sur des modifications post-mortem de la phase minérale de la dentine sclérotique par des phénomènes de déminéralisation et reminéralisation, à l'origine d'une variation de la taille des cristaux d'hydroxyapatite situés dans la zone intra tubulaire et par la substitution du calcium par d'autres éléments, sous l'influence d'une action chimique et/ou bactérienne et donc une influence de l'environnement de la dent (buccal et extérieur). Ce travail nécessite d'être poursuivi, d'une part par l'utilisation de techniques d'imagerie permettant l'association d'une étude structurale, chimique et cristallographique comme la microscopie électronique à transmission, mais également par l'étude des modifications du collagène et des protéines non collagéniques rendant plus accessible les composants minéraux aux facteurs extérieurs. Il serait également pertinent de réaliser les analyses sur des dents d'intervalles post-mortem de dizaines d'années
Introduction: in forensics fields, the identification of human remains is a recurrent problem. Estimating age at death is one of the criteria to be evaluated. In adults, the height of root dentin transparency is used. However, in archaeological material, this phenomenon appears to be inconsistent and related to changes in the appearance of sclerotic dentine. The aim of this study was to observe the changes in sclerotic dentin at different post-mortem intervals, focusing on the mineral part, which is the main component of this tissue and is likely to have more marked variations over longer post-mortem periods.Material and Method: The study included two parts (retrospective and prospective) with 21 monoradicular human teeth, three dating frome the 18th century from archaeological excavations and eighteen from donations of the body to science from the Faculty of Medicine of the University of Lille preserved in equivalent conditions and analyzed at different post-mortem intervals of 0, 1, 2 and 5 years. After resin embedding, the teeth were sectioned and polished, then analyzed by scanning electron microscope, completed by semi-quantitative analysis of calcium and phosphorus using EDS-X microanalysis, as well as broad detection of elements from the periodic table. We then carried out a crystallographic analysis using X-ray diffractometry.Results: The analysis showed the existence of tubular, chemical and crystallographic changes in the sclerotic dentin as a function of the post-mortem interval. Our scanning electron microscope study revealed a difference in the appearance of the tubules linked to an increase post-mortem interval: loss of the peritubular collar and obstruction of the tubule lumen by a hyperdense material. Microanalysis highlighted variations in phosphocalcic ratios among the different groups, notably at the cementum junction and more specifically in the canine, which could be a good predictive model for assessing post-mortem interval. Using diffractometry, we confirmed that the mineral phase of sclerotic dentin, whatever the post-mortem interval, was composed of hydroxyapatite crystals, with a better level of crystallinity in archaeological teeth compared with teeth with a 5-year post-mortem interval, but also between teeth with a 0 and 1 year post-mortem interval, compared with 2 years. Discussion: the differences observed could be due to post-mortem changes of the mineral phase of sclerotic dentin through demineralization and remineralization phenomena, resulting in variations in the size of hydroxyapatite crystals located in the intra-tubular zone and through the substitution of calcium by other elements, under the influence of chemical and/or bacterial action and therefore an influence of the tooth's environment (buccal and external). This work needs to be pursued, on the one hand by using imaging techniques that combine structural, chemical and crystallographic studies, such as transmission electron microscopy, and on the other hand by studying changes in collagen and non-collagenous proteins making mineral components more accessible to external factors. It would also be relevant to carry out analyses on teeth from post-mortem intervals of decades

La structure tubulaire du tissu dentinaire permet de le considerer comme une structure poreuse. Le but de ce travail est d'essayer d'analyser in vitro et in situ, dans un premier temps les facteurs conditionnant la permeabilite de la dentine radiculaire, puis dans un deuxieme temps, les correlations entre l'etat de surface endocanalaire et les variations de permeabilite induites par diverses techniques de preparation endodontiques. La premiere partie comprend deux temps: une etude de la diffusion transdentinaire de solutions colorantes, puis de la permeabilite dentinaire en terme de filtration de fluide, ceci in vitro et in situ. La deuxieme partie est consacree a la mise au point d'une methode d'analyse de cliches de microscopie electronique a balayage par un systeme de traitement et d'analyse d'image permettant la mesure des surfaces recouvertes de boues dentinaires ou de debris organiques. La troisieme partie est consacree a l'etude des variations de permeabilite induites par quatre methodes de preparation endodontiques. L'aspect de la paroi endocanalaire dentinaire evalue par le systeme precedemment decrit est rapproche de ces variations de permeabilite

L’activation du système complément, qui se produit à la suite d’une infection ou d’un trauma, génère de puissants signaux moléculaires capables d’initier la réaction inflammatoire. Parmi ces signaux, le fragment actif C5a permet de recruter sur le site lésé les cellules qui expriment son récepteur (le C5aR/CD88). Bien que le C5aR/CD88 soit initialement connu pour être exprimé par les cellules inflammatoires, il est établi que de nombreuses cellules non immunitaires expriment ce récepteur indiquant son implication dans d’autres processus. Nos résultats ont permis de démontrer que l’activation du système du complément au niveau de la pulpe dentaire est réalisée non seulement à partir des protéines plasmatiques mais aussi des protéines synthétisées par les fibroblastes pulpaires. Ainsi, l’activation locale du système du complément, produit à la suite d’une infection, d’un trauma ou de l’application de biomatériaux, génère du C5a qui induit la migration des cellules progénitrices. Ce travail démontre pour la toute première fois l’implication du fragment actif C5a dans le recrutement de progénitrices pulpaires, étape clef au processus de régénération pulpo-Dentinaire. Ces travaux pourraient donc constituer une piste sérieuse dans l’établissement de nouvelles thérapies permettant de cibler les cellules progénitrices au cours du processus de régénération
After tissue injury or infection, Complement activation provides powerful signals initiating the inflammatory reaction. These events are mediated by biologically active fragments such as C5a which attracts cells expressing its receptor (C5aR/CD88) to the injury site. Besides inflammatory cells as the main C5aR-Expressing cells, various tissue cells have been reported to express this receptor suggesting its involvement in other processes. In order to investigate the possible relationship between complement activation and pulp regeneration, we investigated Complement activation in the dental pulp and progenitor cell migration from their perivascular niches to the pulp injury site to initiate the regeneration process.Our results indicate that complement activation in the dental pulp is the result of both plasma and fibroblast secreted complement proteins. Thus upon local complement activation, which can occur after pathological injury or biomaterials application, C5a induces pulp progenitors’ migration which is critical in initiating the regenerative processes. To our knowledge, this is the first work to demonstrate the involvement of C5a biologically active fragment in the recruitment human pulp progenitor cells. This may provide a useful future therapeutic tool in targeting the progenitor cells in a dentin/pulp regeneration process

Therapies to promote pulp repair and regeneration after injury should be underpinned by a deep understanding of normal tissue behaviour, and cellular signalling mechanisms. The objectives of this work were to understand normal structure of the tooth and to identify changes in its cellular elements and their complex interactions in response to dentine exposure. Revisiting pulp structure and function with a range of contemporary techniques may formalize observations into new concepts of tooth physiology and pathophysiology, and reveal new opportunities for therapeutic intervention. Studies within this thesis employed rodent mandibular incisors and molars with structural and functional investigations on demineralised teeth, non-demineralised freshly extracted pulp tissues and tissue explants. Observations were made on ground sections, haematoxylin-eosin stained sections, immunohistochemically-stained sections, and on quantitative reverse transcription polymerase chain reaction (q-RT-PCR) examination of tissue explants. Complex cellular structure and heterogeneity was observed within odontoblast and subodontoblast cellular populations. Previously undescribed odontoblast processes were identified within the predentine region during crown development and in the radicular pulp after tooth development. Programmed retraction of odontoblast processes was observed after dentine exposure by cavity preparation or tooth wear. Two phases of reactionary dentine deposition (atubular followed by tubular) was identified after tooth wear. This revealed a programmed cellular defensive mechanism which lead to tissue recovery and regeneration. This process could be controlled by autocrine or paracrine signalling mechanisms, as indicated by the presence of NGF and NGFR, in addition to a complex network of CGRP-IR axons. Observations suggested revision of established hypotheses including the hydrodynamic theory of dentine sensitivity and the role of extracellular pH in biomineralisation. This hypothesis could provide coherent explanation for several well-known dental mysteries including pulp stone development, dentine sclerosis and the mode of action of high pH materials (calcium hydroxide, and hydraulic calcium silicate cements) in the repair of pulp wounds.

Ce travail porte sur l'etude de l'arcade dentaire chez de jeunes adultes. Il comporte deux parties: la premiere, conventionnelle, situe l'arcade dentaire dans son environnement anatomo-physiologique en rappelant son origine phylogenique, embryologique et les facteurs influencant son developpement. La seconde decrit le protocole experimental et les resultats obtenus. Menee sur 90 etudiants inscrits en deuxieme annee de chirurgie dentaire, elle a porte d'une part, sur la modelisation individualisee de la forme d'arcade, et d'autre part, sur la recherche de correlations de ces formes avec des parametres dento-maxillo-faciaux classiques. A partir d'une empreinte aux alginates de l'arcade inferieure, certains points ont ete choisis afin de reproduire la courbe sur laquelle se positionnent les dents: le bord libre des incisives, la pointe canine, et les cuspides vestibulaires des premolaires et molaires, dents de sagesse exclues. L'enregistrement des coordonnees est realise par ordinateur a partir d'une camera ccd (charge coupled device) et les donnees ainsi recueillies sont ensuite traitees par le logiciel s-plus. Ces donnees permettent de modeliser de facon individualisee l'arcade enregistree. Nous presentons les principales methodes decrites dans la litterature. Il apparait que celles-ci sont sensibles a l'influence des dents en malposition. Nous proposons ensuite des methodes qui semblent etre plus appropriees aux problemes particuliers des orthodontistes: les ajustements robustes. L'analyse statistique de chaque arcade permet de calculer un coefficient caracteristique de forme. Cet indice est compare aux indices classiquement utilises en morphologie dento-faciale

Pendant des années, l'amélogenine, l'améloblastine et l'énaméline ont été considérées comme exclusives de l'émail dentaire, à la fois structurales et régulant la biominéralisation de ce tissu. Dans ce mémoire, nous avons étudié l'expression de ces trois protéines et leurs transcripts grâce à des analyses descriptives et quantitatives dans différents tissus, en prenant comme repère l'organe de l'émail. Nous avons également établi le patron ontogénique de l'expression de ces molécules avec l'étude de souris sauvages et de mutants nuls pour l'amélogénine à différents stades de dévelopmment. Ces données nous ont permis de confirmer l'expression extra-dentaire de ces molécules. Compte tenu de leur état chimique, leur distribution et leur quantité, nous proposons ces « proteines associées à l'émail » comme des protéines à double rôle ; d'un côté un rôle structural et de l'autre des fonctions de type facteur de croissance dans une voie physiologique intégrée. Ainsi, ces protéines participeraient également à la régulation du métabolisme du complexe alvéolo-dentaire. Enfin, l'ensemble de nos données suggèrent que les différents tissus osseux du squelette peuvent être caractérisés par le profil d'expression de ces protéines, lesquelles pourraient représenter des marqueurs spécifiques des structures osseuses d'origine neuroectodermique
For years, amelogenin, ameloblastin and enamelin have been considered as exclusive of the dental enamel, both structural and regulating biomineralization of this tissue. This work investigates these three proteins and their transcripts through descriptive and quantitative analyses in different hard and soft tissues taking as reference the enamel organ. We establish the ontogenetic pattern bf expression of these molecules using control and amelogenin knock-out mice of different ages. We confirm the expression of these molecules in non-dental tissues. Given their chemical state, their distribution and quantity, we suggest these " enamel related proteins" as proteins with a double rote: a structural rote in enamel but also as signaling molecute, with growth factor-like functions. They would indeed participate in the regulation of the metabolism of dentoatveotar complex. Additionaly, our data suggest that the various skeletal tissues can be characterized by the expression profile of these proteins, which may represent specific markers of neural-crest derived bones

L'objet de cette étude est de rechercher, au niveau de la zone orofaciale, les conséquences d'une absorption trop importante, chronique, d'un élément consommé souvent avec excès : le chlorure de sodium. Après un rappel de physiologie générale et salivaire, nous avons analysé, dans la deuxième partie, l'action d'une absorption chronique trop importante de chlorure de sodium sur les équilibres hydro-électrolytique et acido-basique et les répercussions buccales d'un excès de sel. La troisième et la quatrième parties sont consacrées à une enquête descriptive préliminaire chez les marins-pêcheurs, complétée par des mesures de pH salivaire et de pH urinaire afin de diagnostiquer une possibilité d'acidose ou de "pseudo-acidose" hyperchlorémique due à une absorption chronique trop importante de sel telle qu'elle existe chez les gens de mer. Nous avons pu établir une association causale entre une possibilité d'acidose hyperchlorémique due au sel marin et la carie dentaire, ce qui traduit le fait qu'une absorption chronique trop importante de chlorure de sodium a pour effet une déminéralisation de la dent préalable à l'invasion microbienne et par voie de conséquence à la carie dentaire.

L'odontoblaste est la cellule dentaire responsable de la sécrétion de la dentine. L'invalidation du facteur de transcription Msx2 révélait un dysfonctionnement notable du processus de dentinogénèse. Une dysmorphie radiculaire associée à un enfermement des odontoblastes dans une « ostéodentine », normalement rencontrée au cours des processus de réparation, est présente chez les animaux invalidés pour Msx2, Msx2-/-. Ce travail démontre l'impact de l'homéogène dans le déterminisme de la cellule ectomésenchymateuse lors de la dentinogenèse postnatale. La sclérostine exprimée par les ostéocytes, est connue dans l'ostéogénèse comme élément-clé de différenciation par son action inhibitrice de la voie Wnt//β-catenine. L'analyse de ces deux marqueurs cellulaires communs à l'ostéogenèse et l'odontogénèse sous-tend l'existence d'une biodiversité cellulaire de la pulpe dentaire selon la couronne et racine dentaire. La modélisation des schémas physiologiques par la technique d'effraction pulpaire permet de compléter les données antérieures sur la présence de plusieurs contingents cellulaires dans la pulpe dentaire, fonction de leurs signatures moléculaires. Nos investigations caractérisent une dualité tissulaire dans le même ectomésenchyme pulpaire, concept dont le but ultime est d'être transposé en clinique par le truchement d'une recherche appliquée en biothérapie pulpaire
Odontoblast is the dental cell which responsible to dentine secretion. Msx2 gene invalidation induces defects in dentinogenesis process. Indeed, mice lacking the homeobox gene exhibited a root dysmorphology associated to odontoblast embedded within an "osteodentin", normally noticeable in the reparative process. This work shows the impact of Msx2 in the ectomesenchymal cells fate during the postnatal dentinogenesis. Sclerostin, product of the sostdcl gene and expressed by osteocytes, is known as key regulator of differentiation in osteogenesis by inhibiting Wnt/β-catenin pathway. Analysis of the two cell marker's common to both odontogenesis and osteogenesis support the existence of cellular biodiversity in dental pulp according crown and root compartment. The model for pulp healing permit to complete the first investigations on several cell contingents in dental pulp, depend upon molecular expressions profiles. Our investigations characterize two "sub-tissues" in the pulpal ectomesenchyme, a concept which the ultimate goal is to adapt to clinical practice through a research applied for vital pulp-therapy

Posttraumatic epilepsy is a common consequence of brain trauma. However, little is known about how long-term changes in local excitatory and inhibitory synaptic networks contribute to epilepsy after closed-head brain injury. This study adapted a widely used model of experimental brain injury as a mouse model of posttraumatic epilepsy. Behavioral seizure activity and alterations in synaptic circuitry in the dentate gyrus were examined in mice after experimental cortical contusion brain injury. Spontaneous behavioral seizures were observed in 20% of mice after moderate injury and 36-40% of mice weeks after severe injury. In the dentate gyrus, most mice displayed regionally localized mossy fiber reorganization ipsilateral to the injury that was absent in control mice or sections contralateral to the injury. Extracellular field and whole-cell patch clamp recordings were performed in acute brain slice preparations of the dentate gyrus. Dentate granule cells displayed spontaneous and evoked activity that was consistent with network synchronization and the formation of recurrent excitatory network only in slices that had posttraumatic mossy fiber sprouting. The excitability of surviving hilar GABAergic interneurons, which provide important feedback inhibition to granule cells, was examined at similar time points. Cell-attached and whole-cell voltage-clamp recordings revealed increased spontaneous and glutamate photostimulation-evoked excitatory input to hilar GABA neurons ipsilateral to the injury, versus control and contralateral slices. Despite increased excitatory synaptic input to interneurons, whole-cell voltage-clamp recordings revealed a reduction in inhibitory synaptic input to granule cells. These findings suggest that there are alterations in excitatory and inhibitory circuits in mice with posttraumatic mossy fiber sprouting and seizures after cortical contusion head injury.

Ce travail est consacre a l'etude de la deglutition et de sa fiabilite pour determiner la dimension verticale d'occlusion en prothese complete. L'auteur decrit les elements anatomiques qui interviennent dans cette fonction et aborde la physiologie de la deglutition normale, atypique, l'evolution de la deglutition du nouveau-ne a l'adulte, la physiopathologie et l'incidence du vieillissement sur la deglutition. L'etude de la dimension verticale d'occlusion, des conditions de determination au fauteuil, des differentes methodes utilisees pour son approche et les consequences des erreurs de determination, precedent l'experimentation. Le materiel video-informatique employe pour la recherche est compose de cameras a infra-rouges qui filment une sequence secondairement analysee dans les trois dimensions de l'espace, image par image. L'auteur selectionne 5 patients edentes mono ou bi-maxillaires porteurs de chapes ferromagnetiques stabilisant la prothese mandibulaire, et confectionne pour chaque patient une base mandibulaire sans couloir dentaire, et 4 duplicata realises a -2, -4, +2 et +4 mm par rapport a la hauteur de sa prothese d'usage qui sert de reference. Chaque patient porte un reflecteur colle sur le front et un reflecteur extra-oral colle sur chaque appareil mandibulaire. Chaque patient effectue une serie de deglutition de salive, d'eau, de banane, avec chacun des duplicata, la base et l'appareil d'usage et termine chaque serie par un contact dentaire volontaire. Les differents niveaux de deglutition sont compares dans le plan vertical entre eux, entre les differents appareils, la position d'intercuspidie servant de reference. L'analyse qualitative des resultats conclut au manque de fiabilite de la fonction de deglutition utilisee lors de la determination precise de la dvo en prothese complete

La première partie de cette thèse est consacrée à des rappels bibliographiques sur les mécanismes de la minéralisation osseuse, dentaire et la vitamine D. Dans la deuxième partie les matériels et méthodes de l'expérimentation du 45[exposant]Ca et du 32[exposant]P sous l'influence du 1,25(OH)2[indice]D3[indice] et de différents sels de calcium (CaCo3[indice], CH3[indice]Co2[indice]Ca. . . . ) dans des cultures d'explants de germes d'incisive de la souris suisse albinos sont exposés. L'absorption du 45[exposant]Ca par la dentine est confirmée par historadiographie. Enfin un atlas d'images est tiré de ce travail.

Les épilepsies du lobe temporal médian sont parmi les formes les plus courantes d'épilepsie partielle pharmaco-résistante de l'adulte.Ces épilepsies sont caractérisées par la survenue de crises récurrentes spontanées associées à des décharges synchrones de populations neuronales générées par un réseau multi structural Zone Epileptogène. Le noyau supramammillaire (SuM) innervant tous les cortex limbiques. Chez le rat, il a été démontré qu’il était impliqué dans le contrôle des rythmes thêta de l’hippocampe et des fonctions associées telles que le sommeil paradoxal, ainsi que l’apprentissage et la mémoire émotionnelle. Il a été démontré que les projections des neurones de la région latérale du SuM (SuML) qui innervent le gyrus dentelé dorsal (dDG) présentent un phénotype unique à la foie GABAergique et Glutamatergique. De plus cette voie est réorganisée chez les animaux épileptiques. Dans cette thèse, nous démontrons que:Tous les neurones du SuML innervant le DG co-expriment les marqueurs pour les neurotransmissions GABAergique et glutamatergique. L'activation de cette voie augmente la puissance et la fréquence des oscillations thêta ainsi que la puissance du gamma,pendant le SP et induit la décharge des CGs.La population de neurones GABA / GLU du SuML innervant le dDG est hétérogène. Parmi ces neurones,70% contiennent la calrétinine et 30% n'en contiennent pas.Chez les souris épileptiques, la voie SuML-dDG est réorganisée . Nos résultats préliminaires utilisant les techniques d’optogénétique in vivo montrent que l'activation ou l'inactivation de cette voie ne modifie pas la durée de la crise. Cependant, cette voie module la variabilité de la contenu fréquentiel des crises
Mesial temporal lobe epilepsies are among the most common clinical forms of drug-resistant partial epilepsies in adults. These epilepsies are characterized by the occurrence of spontaneous recurrent seizures associated with excessive and hypersynchronous discharges of neuronal populations generated by a multi-structural epileptogenic zone involving several regions of the limbic system. The Supramammillary nucleus (SuM) is innervating all limbic cortex. In rat, it has been shown to be involved in the control of hippocampal theta rhythms and associated functions such as REM sleep as well as emotional learning and memory. More recently, it was shown that the projections from neurons of lateral region of the SuM (SuML) that innervate the dorsal dentate gyrus (DG) display a unique GABAergic and Glutamatergic neurotransmitter phenotype and this pathway is reorganized in epileptic animals. In this thesis,we demonstrated that: All the neurons from the SuML innervating the dDG co-express markers for both GABAergic and glutamatergic neurotransmissions. Activation of this pathway increases theta power and frequency as well as gamma power during REM sleep and induced net firing of some GCs. The population of GABA/GLU SuML neurons innervating the dDG is heterogeneous. Among these neurons 70% contain calretinin whereas 30% do not. In epileptic mice the SuML-dDG pathway is reorganized . Our preliminary results using in vivo optogenetic show that activation or inactivation of this pathway do not modify the seizure duration. However, this pathway modulates the variability of the seizure frequency content

Instrumental to forensic investigations is the ability to identify unknown human remains providing key evidence to criminal cases, resolution to missing persons, and assistance in mass or natural disasters. Identification of remains in an effort to determine age is an area of forensics that has received considerable attention. Traditional methods in age determination such as morphology are often biased, antiquated, and frequently result in a large margin of error. Conversely, the emergence of new forensic techniques provide promise to reduce the margin of error in determining age. One such technique has focused on relating the extent of amino acid racemization in teeth to age. Past research has focused primarily on the analysis of aspartic acid due to its high racemization rate. Our research indicates that glutamic acid also shows promise as related to age determination. Results will be presented illustrating optimization of gas chromatography using a chiral column for separation of amino acids found in dentin and their enantiomeric ratio quantification. Age correlation data will be presented on collected teeth ranging from mid-teens to early seventies.

Les 161 recueils de masséter (161 gauche 36 droite) ont intéressé des patients lors du traitement chirurgical de leur malocclusion. Les 161 patients sont regroupés selon l'analyse céphalométrique de Delaire informatisée. L'étude des chaînes lourdes de myosine a été effectuée sur 28 échantillons par électrophorèse (SDS-PAGE) et western-blot. L'immunomarquage a été réalisé sur les 197 biopsies (côté gauche 161 et côté droit 36) et permet d'identifier 4 groupes de fibres du masséter humain (l, Hybride, II, NéoAtrial) selon leur pourcentage et leur surface moyenne. Nous avons réalisé des tests de Student apparié et de Wilcoxon pour comparer les résultats des 28 échantillons selon l'immunomarquage et l'électrophorèse, et les deux côtés pour les patients déviés ou non. Nous avons réalisé un test d'ANOVA entre chaque type de fibre et les groupes. Les résultats de l'électrophorèse et de l'immunomarquage sont identiques, validant la faible variabilité intrinsèque à l'échelle de la biopsie. La comparaison des patients déviés conclut à une différence significative du côté homolatéral à la déviation chez les patients déviés (pourcentage de fibres de type II p=0,0286). Le morphotype deepbite est associé à une élévation du pourcentage des fibres de type II (p=0,0073) et à une baisse de la surface moyenne des NéoAtriale (p=0,0401). Le morphotype classe II apparait associé à une augmentation du pourcentage de fibres hybrides (p=0,0419) et une baisse du pourcentage de fibres de type II (p=0,0234) par rapport à la classe Ill. La position absolue de la mandibule par rapport à la base du crâne est liée au pourcentage (p=0,0023) et la surface moyenne (p=0,0387) des fibres de type Hybride (augmentation dans les pro et rétro-mandibulie, baisse dans les normo-mandibulie) CONCLUSION La hauteur faciale et la latérodéviation sont liées au pourcentage de fibres de type II et à la surface moyenne des fibres NéoAtriales. La position sagittale de la mandibule est liée au pourcentage et la surface moyenne des fibres Hybrides, et au pourcentage de fibres de type II
Masseter biopsies (161left, 36 right).were performed on 161 subjects undergoing surgical treatment of malocclusion. Patients were classified according to computer-assisted Delaire cephalometric analysis. The 36 patients with both side biopsies were separated into 2 groups: with or without lateral deviation. SDS-PAGE was performed on 28 biopsies to identify myosin heavy chain content. Immunostaining with myosin-isoform-specific antibodies was performed on 197 biopsies to identify 4 fiber types (l, Hybrid, II, NéoAtrial). For each fiber type, percent occupancy and mean area were calculated. Student and Wilcoxon tests were used to compare electrophoresis and immunostaining results from 28 cases, and fibre type compositions on the two sides in 36 patients. An ANOVA test was done to identify correlation between percent occupancy and mean area of each fiber type versus cephalometric classification for aIl 161 left samples. Electrophoresis and immunostaining analysis of slow and fast (lIa & IIx) myosin heavy chains gave equivalent results. Lateral deviation patients showed an increase of type II fiber occupancy (p=0,0286) on the same side as the deviation (short side). Deep bite is associated with an increase of type II fiber occupancy (p=0,0073) and decrease of NeoAtrial mean fiber area (p=0,0401). Class II is significantly associated with an increase in occupancy of hybrid fibers (p=0,0419) and decrease of type II (p=O,0234) as compared with Class Ill. Mandibular position in relation to the skull base trend is associated with an increase of percent occupancy (p=0,0023) and mean area (p=0,0387) of hybrid fibers in case both forward and backward position. CONCLUSION Facial vertical dimension and mandibular lateral deviation is significantly linked to type II fiber percentage occupancy and NeoAtrial mean fiber area. Saggital mandibular position is linked to mean fiber area and percent of hybrid fibers, and percent occupancy of type II fibers

Dans le cadre d'une étude transversale menée sur 202 patientes ménopausées et non ménopausées,les objectifs sont de démontrer l'existence d'un lien entre ménopause et altération de l'état de santé buccodentaire. D'évaluer l'action du THM sur la morbidité dentaire et «in fine» sur la mortalité dentaire.De préciser les liens entre santé bucco-dentaire et diverses pathologies générales et d'apprécier les liens entre psychisme et soma chez les femmes ménopausées. D'apprécier l'influence des biphosphonates sur l'état de santé parodontal.De placer l'étude des liens état bucco-dentaire- ménopause dans une optique sociétale et anthropologique.La ménopause a pour conséquence une altération du parodonte (p=0,003).Le THM a une action bénéfique sur le parodonte.L'effet biologique du diabète est drastique quant à la perte des organes dentaires (p=0,050).L'étude souligne l'influence «per se» d'un mauvais état bucco-dentaire pour la pathologie coronarienne (OR=1,214). De plus,évènements stressants,sècheresse buccale,pathologies ostéo articulaires,carence hormonale sont des facteurs diversement liés de la mortalité dentaire durant cette période. Par ailleurs, il est apparu que les femmes ayant été récemment traitées pour un cancer du sein développaient plus de caries dentaires (p=0,031 OR=2,161). L'étude met en évidence les effets des biphosphonates sur l'altération du parodonte (p=0,011) malgré la prise d'un THM (p=0,020).Un milieu socioculturel aisé contribueraient à la médicalisation du phénomène physiologique.Le fait de vivre seule influerait sur la perte des organes dentaires (p=0,035). Enfin,la pratique régulière d'un sport améliorerait l'état de santé orale (p=0,036)
In a cross-sectional study of 202 postmenopausal and premenopausal women,the objectives of this study are to demonstrate a link between menopause and altered state of oral health.To evaluate the action of HRT on dental disease and finally on the tooth mortality. To assess and clarify the relationship between oral health and various general diseases and links between psyche and soma in postmenopausal women.Also discussed was the influence of bisphosphonates on the state of periodontal health.Finally,it was decided to place the study links oral menopausal status in a social and anthropological perspective.It appears then that menopause results in an altered state of oral health,(p = 0.003).HRT has a beneficial effect on the periodontal disease.The biological effects of diabetes are related to dental mortality (p = 0.050). This study emphasize the influence "per se" a bad oral health status for coronary artery disease (OR = 1.214).In postmenopausal women, stressful events, dry mouth, joint and bone diseases, hormonal deficiency are factors variously related dental mortality during this period. Moreover, it was found that women who have recently been treated for breast cancer developed more dental caries (p = 0.031 OR = 2.161).The study related the effects of bisphosphonates on the alteration of periodontal (p = 0.011), despite taking HRT (p = 0.020).In addition,background socio-economic favored contribute to the medicalization of physiological phenomenon. The fact of living alone would affect the loss of dental organs (p = 0.035). Finally, the regular practice of a sport improve the state of oral health (p = 0.036)

Yes
Abstract: The reconstruction of the diet of past populations using the stable isotope analysis of bone collagen has become a well-established tool for examining their lifeways. For example, variations in foods ingested can demonstrate differences in the foods available to individuals of different sex, age, status and in some cases identifying migrants. However, because of the remodelling of bone throughout life, this produces average values which have been incorporated in the tissues over a period of time and gives a blurred picture of the diet. The analysis of the stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) from tiny increments of dentine utilizes tissue that does not remodel and that permits comparison, at the same age, of those who survived infancy with those who did not at high temporal resolution. Here, we present a study of teeth from a Great Famine period workhouse cemetery in Kilkenny, Ireland, and a contemporary 19th-century cemetery in London, England and compare these with published data from early Neolithic individuals from Sumburgh, Shetland, Scotland. Covariation in δ13C and δ15N values suggests that even small variations have a physiological basis. We show that high-resolution intra-dentine isotope profiles can pinpoint shortduration events such as dietary change, and in the historical populations these can be related to known periods of nutritional deprivation in the juvenile years of life. We further suggest that the data from the Famine cemetery individuals suggest a physiological marker within these isotope profiles for a period of nutritional deprivation which could be utilised in other periods and geographical areas, particularly where there is a catastrophic cemetery assemblage with no known aetiology. This technique could also have applications in a forensic setting.

The neurotoxin kainate produces hippocampal lesions which in turn induce the mossy fibers, the axons of the dentate granule cells, to sprout collaterals. These collaterals grow across the granule cell body layer and appear to synapse on the dendrites of the granule cells. If these synapses are functional, a recurrent excitatory circuit will have formed in the dentate. As hippocampal tissue taken from human temporal lobe epileptics show similar pyramidal cell loss and mossy fiber sprouting, the KA-treated animal has been proposed as a model for temporal lobe epilepsy (Nadler, 1981) Tauck and Nadler (1985) have presented data suggesting mossy fiber sprouting is associated with the generation of multiple population spikes in the dentate in response to hilar stimulation. Because normally only a single population spike is evoked, these data suggest the sprouted mossy fibers have formed a functional circuit. To further assess the physiology of dentate granule cells after mossy fiber sprouting, intracellular and extracellular recordings from hippocampal slices were performed As a preliminary step in examining mossy fiber sprouting in the kainate treated rat, we studied the electrically evoked responses in the dentate gyrus of normal rats under conditions of heightened excitability. After blocking GABA$\sb{\rm A}$ receptors with bicuculline (30 $\mu$M), a second population spike was evoked to hilar stimulation. In higher concentrations of GABA$\sb{\rm A}$ blockers (100 $\mu$M bicuculline or picrotoxin), three to four population spikes were evoked to hilar stimulation. After raising (K$\sp+$) from 3 to 10 mM in 30 $\mu$M bicuculline, four to five population spikes were evoked. These data indicate multiple population spikes to hilar stimulation do not require mossy fiber sprouting Experiments conducted on kainate-treated rats revealed that in normal medium hippocampal slices from both animals with and without mossy fiber sprouting had normal responses. When GABA$\sb{\rm A}$ responses were blocked with 30 $\mu$M bicuculline, rats with mossy fiber sprouting showed bursts of population spikes after long and variable delays to low-intensity hilar stimulation. Some slices from hippocampi with mossy fiber sprouting also showed spontaneous population bursts in bicuculline. These responses were not seen in treated animals which did not sprout mossy fiber collaterals. Based on computer simulations and experiments on other brain areas, these responses suggest local recurrent excitatory circuits have formed. These data also argue that the responses of the dentate gyrus with mossy fiber sprouting are normal, and show abnormality only when inhibition is depressed Mossy fiber sprouting has been documented in human tissue taken from temporal lobe epileptics (Houser et al., 1990). We have developed methods for assessing mossy fiber sprouting in tissue taken from humans during surgery for intractable epilepsy
acase@tulane.edu

Adult hippocampal neurogenesis—a unique form of plasticity in the dentate gyrus (DG)—is regulated by experience, and when manipulated can have specific effects on behavior. Different methods have been used over the years to study new neurons’ functional role in the hippocampus, many of which focus on ablating neurogenesis. While ablation methods can test the necessity of adult-born granule cells (abGCs) for behavior, these techniques remove all abGCs from the circuit and thus do not allow one to determine which properties of abGCs are required for behavior. Such information is required to understand the mechanism of their action. Thus, new strategies are needed to determine what properties of young abGCs allow them to distinguish themselves from their mature counterparts and uniquely impact behavior. Recent hypotheses have suggested that the enhanced synaptic plasticity exhibited by 4–6-week-old abGCs allows them to uniquely contribute to hippocampal circuit function, and thus behavior. The primary goal of this thesis was to explore the contribution young abGCs’ heightened synaptic plasticity makes to hippocampal function. This was achieved using a transgenic mouse approach that allowed for the conditional deletion of NR2B from abGCs. Overall, iNR2BNes mice generated the same number of new neurons in adulthood as control mice at baseline. These neurons survived and matured with only a slight reduction in dendritic complexity. However, a potentially important electrophysiological property of these neurons—their enhanced synaptic plasticity—had been eliminated. From an electrophysiological standpoint, iNR2BNes mice resemble mice with ablated neurogenesis, while from all other neurogenic standpoints examined they most closely resemble wild-type mice. Consequently, these mice provided a novel model to test the extent to which young abGCs’ enhanced plasticity contributes to hippocampal-dependent behaviors. The results reveal that eliminating NR2B-containing NMDA receptors from abGCs does not alter baseline anxiety or antidepressant (AD)-like behavior. However, iNR2BNes mice differed from controls in measures of cognitive function. These mice were able to learn in the contextual fear conditioning test, but were impaired in the more difficult contextual fear discrimination test. Mice also exhibited a decreased novelty exploration phenotype that impaired their performance in the novel object recognition test. Together, these results indicate that the NR2B-dependent heightened plasticity exhibited by 4–6-week-old abGCs is necessary for responses to novelty and fine contextual discrimination, but does not contribute to baseline anxiety or emotionality. AD treatment increases levels of adult neurogenesis in the hippocampus, and these newborn neurons have been shown to be necessary for some of the behavioral effects of ADs seen in rodents. In addition, the maturation timeline of adult neurogenesis correlates with the onset of behavioral responses to ADs. ADs also enhance a neurogenesis-dependent form of long-term potentiation (LTP) in the DG evoked by medial perforant path stimulation under intact GABAergic tone called ACSF-LTP. Thus, a potential mechanism by which abGCs may contribute to AD behavioral efficacy is by providing extra plastic units to the DG circuit. This theory was tested by once again using the mouse line in which NR2B can be conditionally deleted from abGCs in the DG. Here, we found that deletion of the NR2B subunit significantly attenuated a neurogenesis-dependent behavioral response to fluoxetine in the novelty suppressed feeding test, and additionally blocked fluoxetine’s ability to enhance young abGCs’ maturation and subsequent integration into the hippocampal network. This suggests that eliminating abGCs’ enhanced plasticity decreases their ability to influence DG output resulting in an AD response that is less robust than seen in control mice. Control experiments revealed the specificity of this effect, as NR2B deletion did not impact the effect of fluoxetine in a neurogenesis-independent behavioral assay (tail suspension test) or in an assay that was insensitive to fluoxetine in this strain of mice (elevated plus maze). Our efforts to isolate the contribution of abGCs’ unique physiology from the neurogenic effects of fluoxetine were not entirely successful as the results presented here also revealed slight group differences in neurogenesis between control mice and mice lacking NR2B in young neurons. Yet, this data still supports the idea that fluoxetine increases the ability of abGCs to participate in DG output by increasing the chance that new neurons will be activated during DG stimulation. This may be achieved either by increasing their overall number, increasing their potential to make synaptic connections, or increasing their ability to strengthen their connections. However, due to the close link between activity and maturation that appears to be enhanced with fluoxetine treatment, a different approach with greater temporal resolution is needed to separate the neurogenic effects of fluoxetine from the physiological contribution abGCs make to hippocampal output. With this in mind, a mouse line in which abGCs could be temporally inhibited was also generated. Cellular and behavioral characterization of mice conditionally expressing hM4Di—a mutated muscarinic acetylcholine receptor that is insensitive to endogenous acetylcholine, but can be activated by the biologically inert, highly bioavailable compound, clozapine N-oxide (CNO)—has begun. Results show that acute CNO treatment in mice expressing this designer receptor exclusively activated by a designer drug (DREADD) in DG granule cells can impair encoding of contextual fear memory. Chronically treating these mice had an anxiogenic effect in the open field test, but otherwise anxiety and emotionality in these mice were comparable to controls. Chronic CNO treatment in mice expressing hM4Di in young abGCs effectively decreased these cells’ dendritic complexity, but did not alter proliferation or early survival. Thus, hM4Di DREADDs represent a novel tool that can be used to modulate activity of neurons in a temporally restricted manner, allowing for both acute and chronic manipulations of hippocampal granule cells. The experiments put forth in this thesis will highlight the importance of abGCs enhanced plasticity. The utility as well as potential pitfalls of the mouse models used here to test theories of abGC function will also be explored. Hopefully this analysis will provide an improved framework in which future experiments can be developed with the aim of uncovering novel insights into the hippocampal circuitry that underlies learning and memory and discovering new strategies for the treatment of neurological and psychiatric disorders.

Indiana University-Purdue University Indianapolis (IUPUI)School of dentistry
BACKGROUND: Fluoride and stannous ions have been reported to be relevant for dental erosion prevention. However, their interaction with the acquired dental pellicle (ADP), a clinically relevant erosion protective factor, is not well known and needs to be investigated. OBJECTIVES: To investigate the anti-erosive properties of fluoride-containing solutions and stannous solutions on enamel and dentin surfaces with a previously formed ADP. To characterize the protein profile of the ADP treated with the test solutions. METHODS: Phase I tested four solutions: SnCl2/NaF, NaF, SnCl2 and deionized water (DIW) (as negative control). Forty bovine enamel and dentin specimens 104 (4x4x2 mm3) were prepared and randomly distributed into 4 groups (n = 10). The specimens were incubated in clarified human saliva (CHS) for 24 h for pellicle formation and then they were subjected to a cycling procedure that included a 5-min erosive challenge (0.3-percent citric acid, pH 2.6); a 2-min treatment with the solution (between 1st, 3rd and 6th cycles); a 2-h immersion in CHS, and overnight immersion in CHS. Cycles were repeated 6x/day for 5 days. The outcome measure was surface loss (SL) using profilometry. Phase II: Thirty-two (32) bovine enamel specimens (882 mm3) (n = 8) were similarly prepared and incubated in saliva for 24 h and then treated with the solutions for 2 min followed by CHS immersion for 2 h. This cycle was repeated 3x for one day. The pellicles formed and treated with the test rinse solutions were collected, digested, and analyzed for specific protein content using liquid chromatography electrospray ionization tandem mass spectrometry (LCESI-MS/MS). RESULTS: Phase I: for enamel, SnCl2/NaF, SnCl2, NaF solutions provided 89 percent, 67 percent, and 42 percent SL reduction respectively compared with the control, while in dentin they provided 60 percent, 23 percent, and 36 percent, respectively, all significant at p < 0.05. Phase II: Seventy-two (72) common proteins were identified in all groups, 30 exclusive to DIW, 20 to SnCl2/NaF, 19 to NaF, and 13 to SnCl2. SnCl2/NaF increased the abundance of pellicle proteins than each one alone. CONCLUSION: SnCl2/NaF showed the best anti-erosive effect on both enamel and dentin. The findings suggest that the composition of acquired pellicle changes with different solutions, which may be related to their anti-erosive effect.