1,720,972 research outputs found
Vitamin d and nanostructured surfaces in osteoblastic differentiation of dental stem cells
Full text link1α, 25-diidrossivitamina D3 (1,25(OH)2D3), il metabolita attivo della Vitamina D (Vit D), aumenta
l'assorbimento intestinale di calcio e fosfato, mantenendo un corretto bilanciamento nel
rimodellamento osseo. La Vit D ha un effetto anabolizzante sul sistema scheletrico ed è
fondamentale nel promuovere il differenziamento osteoblastico di cellule staminali mesenchimali
umane (hMSCs) isolate da midollo osseo. Al fine di superare alcuni aspetti negativi associati
all'utilizzo di MSCs da midollo osseo quali morbilità, dolore e bassa resa di cellule, sono state
studiate fonti alternative di tali cellule. Le MSCs possono essere isolate anche dal dente nella sua
forma immatura, il germoglio dentale: le Cellule Staminali da Gemma Dentale (Dental Bud Stem
Cells - DBSCs) sono cellule staminali adulte che possono effettivamente differenziare in senso
osteoblastico.
Lo scopo del progetto è quello di studiare l'effetto della Vit D sulle DBSCs, che rappresentano un
modello utile per comprendere l'attività anabolica delle cellule ossee a partire da precursori
osteoblastici molto indifferenziati.
Dal momento che l'adesione delle MSCs alla Matrice Extra Cellulare (ECM) è ancora poco
caratterizzata, così come il ruolo delle proteine della ECM nella regolazione del differenziamento
osteogenico, abbiamo innanzitutto studiato il nostro modello cellulare di DBSCs per l'espressione di
Integrine e Caderine così come per l'interazione con proteine della ECM.
Abbiamo osservato che le DBSCs mostrano un modello di adesione molecolare paragonabile a
quello descritto per le MSCs.
Abbiamo dimostrato una differenziazione delle DBSCs in senso osteogenico con acquisizione di un
fenotipo osteoblastico, incrementata dal trattamento con la Vit D. Abbiamo osservato che le
DBSCs, trattate con 1,25(OH)2D3, esprimevano livelli più elevati dei principali marcatori
osteoblastici e formavano noduli di matrice mineralizzata in vitro.
Questi risultati riflettono l'origine mesenchimale delle DBSCs e confermano le loro caratteristiche
osteoblastiche.
Inoltre, al fine di chiarire l'effetto del microambiente sul comportamento delle DBSCs, abbiamo
analizzato anche la distribuzione dell’integrina αVβ3 e la formazione di Adesioni Focali (FAs) in
cellule seminate su superfici con diversi rivestimenti in presenza di Vit D. Abbiamo quindi
osservato che la Vit D sembra indurre l’espressione di tali adesioni focali nel nostro modello
cellulare.
Le nostre osservazioni suggeriscono che la Vit D sia in grado di agire direttamente su queste
cellule, che possono essere considerate dei precursori degli osteoblasti, indirizzandole verso una
formazione ossea più elevata.1α,25-dihydroxyvitamin D3 (1,25(OH)2D3), the active metabolite of Vitamin D (Vit D), increases
intestinal absorption of calcium and phosphate, maintaining a correct balance of bone remodeling.
Vit D has an anabolic effect on the skeletal system and is key in promoting osteoblastic
differentiation of human Mesenchymal Stem Cells (hMSCs) from bone marrow. In order to
overcome some negative aspects connected with the use of MSCs from bone marrow, i.e.
morbidity, pain and low yield of cells, other sources of MSCs have been examined. MSCs can be
also isolated from the immature form of the tooth, the dental bud: Dental Bud Stem Cells (DBSCs)
are adult stem cells that can effectively undergo osteoblastic differentiation.
The aim of the project is to study the effect of Vit D on DBSCs, which represent a useful model to
understand the anabolic activity of the bone cells, starting from very undifferentiated osteoblast
precursors.
Since MSCs adhesion to Extra Cellular Matrix (ECM) is still poorly characterized, as well as ECM
proteins role in regulating osteogenic differentiation, we studied our cell model of DBSCs for the
expression of Integrins and Cadherins as well as for ECM protein interaction.
We demonstrated a functional osteogenic differentiation of DBSCs towards an osteoblastic
phenotype, being incremented by the Vit D treatment. We observed that DBSCs treated with
1,25(OH)2D3, expressed increased levels of the main osteoblastic markers and formed mineralized
matrix nodules in vitro.
These results reflected the mesenchymal origin of DBSCs and confirmed their osteoblast-like
features.
Moreover, in order to elucidate the effect of the microenvironment on DBSCs behavior, we also
analyzed αVβ3 integrin distribution and Focal Adhesion formation in cells seeded on surfaces with
different coatings in the presence of Vit D. We observed that Vit D seems to induce the expression
of focal adhesions in our cell model.
Our observations suggest that Vit D acts directly on these cells, that can be considered osteoblast
precursors, directing them to an increased bone formation
“COMPOSIZIONI COMPRENDENTI O COSTITUITE DA POLIDATINA PER USO NEL TRATTAMENTO DELLE PATOLOGIE OSSEE
Full text linkMolecules Inducing Dental Stem Cells Differentiation and Bone Regeneration: State of the Art
No full textTeeth include mesenchymal stem cells (MSCs), which are multipotent cells that promote tooth growth and repair. Dental tissues, specifically the dental pulp and the dental bud, constitute a relevant source of multipotent stem cells, known as dental-derived stem cells (d-DSCs): dental pulp stem cells (DPSCs) and dental bud stem cells (DBSCs). Cell treatment with bone-associated factors and stimulation with small molecule compounds are, among the available methods, the ones who show excellent advantages promoting stem cell differentiation and osteogenesis. Recently, attention has been paid to studies on natural and non-natural compounds. Many fruits, vegetables, and some drugs contain molecules that can enhance MSC osteogenic differentiation and therefore bone formation. The purpose of this review is to examine research work over the past 10 years that has investigated two different types of MSCs from dental tissues that are attractive targets for bone tissue engineering: DPSCs and DBSCs. The reconstruction of bone defects, in fact, is still a challenge and therefore more research is needed; the articles reviewed are meant to identify compounds useful to stimulate d-DSC proliferation and osteogenic differentiation. We only consider the results of the research which is encouraging, assuming that the mentioned compounds are of some importance for bone regeneration
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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