1,721,034 research outputs found
Tooth Enamel: Frontiers in Mineral Chemistry and Biochemistry, Integrative Cell Biology and Genetics
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Roles and functions of amelogenin in the biomineralization of tissues of the alveolo-dental complex
No full textLes protéines amélaires (EMP) ont longtemps été considérées comme exclusives de l’émail, nécessaires pour sa structure et sa biominéralisation. De plus en plus d’études ont également montré leur expression et leur implication dans la signalisation osseuse. Ce travail propose de revisiter les rôles physiologiques et physiopathologiques de l’AMEL et de l’AMBN dans la biominéralisation des tissus alvéolo-dentaires. Pour être fonctionnelles, les EMP nécessiteraient d’être phosphorylées. Les conséquences de leur absence de phosphorylation sont peu connues. C’est pourquoi, nous avons analysé par des méthodes physico-chimiques, les tissus minéralisés dentaires d’un patient porteur d’une mutation de FAM20A, qui serait responsable de la phosphorylation des EMP. Les résultats ont mis en évidence une altération de structure et de minéralisation de l’émail alors qu’aucun défaut dentinaire n’a été observé. Par ailleurs, de nombreuses minéralisations ectopiques dans lesquelles l’AMEL a été immunolocalisée, ont été retrouvées au niveau de l’organe de l’émail. L’expression de l’Amel a été ensuite étudiée par HIS dans les différents compartiments alvéolo-dentaires, pendant la radiculogenèse et au stade adulte. Nos données ont montré une modulation de l’expression d’Amel, dans l’os alvéolaire et dans le ligament, qui pourrait être expliquée d’une part par la formation de la couronne et d’autre part par une réponse aux contraintes biomécaniques dans l’objectif de maintenir un os fonctionnel, via sa participation dans les processus d’ossification primaire et secondaire, en agissant sur la différenciation ostéoblastique. Ces différents résultats mettent en lumière le rôle important de l’AMEL dans la biominéralisation, tant au niveau structural que dans sa fonction de signalisation où elle participerait à la formation et au maintien du complexe alvéolo-dentaire.Enamel proteins (EMPs) have long been considered as exclusive of the dental enamel, necessary for its structure and biomineralization. However, increasing studies have shown their expression and involvement in bone signaling. This work is proposing to revisit the physiological and physiopathological roles of AMEL and AMBN in the biomineralization of alveolodental tissues. To be functional, EMPs would need to be phosphorylated. Consequences of the lack of phosphorylation are not very much known. For this reason, we analyzed, using physicochemical methods, the mineralized dental tissues of a patient carrying a FAM20A mutation, which would be responsible for the phosphorylation of EMPs. The results revealed an alteration in the structure and mineralization of the enamel, while no dentinal defect was observed. In addition, many ectopic mineralization, in which AMEL has been immunolocated, have been found in the enamel organ. Amel expression was then studied by ISH in different alveolodental compartments during radiculogenesis and at the adult stage. Our data showed a modulation of Amel expression in the alveolar bone and ligament, which could be explained on the one hand by the crown formation and on the other hand by a response to biomechanical constraints in order to maintain a functional bone, through its participation in the primary and secondary ossification processes, by acting on osteoblastic differentiation. These different results highlight the important role of AMEL in biomineralization, both at the structural level and in the signaling function, where it would participate in the formation and maintaining of the alveolodental complex
FAM20A in physiological and ectopic biomineralization
No full textLe syndrome rénal de l'émail (ERS) est un trouble récessif rare causé par des mutations de perte de fonction dans FAM20A (famille avec similarité de séquence 20 membres A, OMIM 611062). L'ERS est caractérisé par une hypoplasie de l'émail, une gencive hyperplasique avec des calcifications ectopiques (rénales, pulmonaires, gingivales) et un arrêt de l'éruption dentaire. Le phénotypage complet nous a permis de confirmer un phénotype bucco-dentaire assez spécifique caractérisé par une amélogenèse imparfaite généralement sévère, affectant à la fois la denture temporaire et permanente, des anomalies d'éruption dentaire, des hyperplasies gingivales de sévérité variable et des calcifications ectopiques au niveau gingival mais aussi pulpaire. La présence des minéralisations ectopiques dans des zones telles que les foramens de conjugaison des vertèbres ont été également identifiée. Les analyses histopathologiques de la gencive démontrent une couche papillaire élargie associée à une angiogenèse aberrante et une lamina propia présentant des changements significatifs dans la composition de matrice extracellulaire, y compris une perturbation du réseau de fibres de collagène I. Les analyses d'immunomorphologie et analyses ultrastructurales de calcification du tissu conjonctif de la gencive des patients ERS ont indiqué que le processus de calcification était associé à une dégénérescence épithéliale et à la transformation des fibroblastes gingivaux en cellules de type chondro/ostéoblastique. Les cultures de fibroblastes gingivaux mutants ont tendance à se calcifier et à exprimer de manière anormale des marqueurs ostéoblastique. L'étude de l'amélogénèse dans la lignée de souris FAM20A KI (modèle physiopathologique ERS) démontre que l'absence de Fam20A provoque la perte d'orientation des améloblastes de sorte que la matrice d'émail ne puisse pas se déposer de façon organisée. Cette observation est en accord avec les modifications de la morphologie de l'émail. L'ensemble de ces résultats révèlent un rôle potentiel de FAM20A dans la prévention de la calcification aberrante des tissus oraux et extra-oraux et mettent en évidence des aspects de la pathogenèse de l'ERS.Renal enamel syndrome (ERS) is a rare recessive disorder caused by loss-of-function mutations in FAM20A (20-member sequence similarity family A, OMIM 611062). ERS is characterized by hypoplastic enamel, hyperplastic gingiva with ectopic calcifications (renal, pulmonary, gingival), and delayed or failed tooth eruption. The complete phenotyping allowed us to confirm a fairly specific oral phenotype characterized by generally severe amelogenesis imperfecta, affecting both temporary and permanent dentition, dental eruption anomalies, gingival hyperplasia of varying severity and ectopic calcification at the gingival level but also pulp. The presence of ectopic mineralization in areas such as the conjugation foramina of the vertebrae has also been identified. Histopathologic analysis of the gingiva shows an enlarged papillary layer associated with aberrant angiogenesis and a lamina propia displaying significant changes in its extracellular matrix composition, including disruption of the collagen I fiber network. Ectopic calcifications are found throughout the connective gingival tissue. Immunomorphological and ultrastructural analyses indicate that the calcification process is associated with epithelial degeneration and transformation of the gingival fibroblasts to osteoblastic-like cells. Mutant gingival fibroblasts cultures are prone to calcify and abnormally express osteoblastic marker. The study of amelogenesis in the FAM20A KI mouse line (physiopathological model ERS) demonstrates that the absence of Fam20A causes the loss of orientation of the ameloblasts so that the enamel matrix cannot be deposited in an organized manner. This observation is in agreement with the changes in the morphology of the enamel. Taken together, these results reveal a potential role for FAM20A in preventing aberrant calcification of oral and extraoral tissues and highlight aspects of the pathogenesis of ERS
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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