1,721,181 research outputs found
Crystalline Calcium Alendronate Obtained by Octacalcium Phosphate Digestion: A New Chance for Local Treatment of Bone Loss Diseases?
No full textOctacalcium phosphate (OCP) interaction with alendronate (AL) solution results in the complete digestion of OCP: calcium ion is recruited by the bisphosphonate to yield quantitative precipitation of crystalline calcium alendronate monohydrate. This compound improves osteoblast differentiation and inhibits osteoclast proliferation and activity, both alone and, even more, in combination with OCP
Micro-CT of 3D vascular structures: clues for innovative scaffolds in organ engineering
No full textOrgan transplantation is the only definitive treatment for patients with incurable
diseases of soft and hard tissue structures, including parenchyma and bones.
However, shortage and aging of cadaveric and alive donors, and a number of other
ethical and clinical issues render complex any organ transplant1. A recent hope has
been raised by regenerative medicine and tissue engineering, but current
methodologies are yet limited to the reconstruction of either tissue fragments or
implantation of biocompatible scaffolds to be colonized by the regenerating areas.
Although recent advancement in material science and stem cell biology has led to
biocompatible scaffolds more efficient than in the past, still these constructs are
designed without any anatomy of the vasculature intrinsic to the recipient organ,
based on the assumption that nutrients and oxygen are supplied by diffusion from
adjacent tissues2. Since in both parenchyma and bones the tissue mass grows
around a complex vascular tree, we have recently developed an innovative
bioengineering approach to reconstruct on the laboratory bench an entire bioartificial
organ with a pre-formed internal vascular network acting as a natural scaffold for
seeded stem cells, and as a guide for colonizing vessels, possibly improving the
functional and transplantation performance of the bioconstruct 3. Micro-CT play a key
role to obtain visual and numerical information on the complex vascular geometry of
the organ to be engineered. We here present data on vascular casts of the rat lungs,
and human kidney and thyroid gland, to be used in the development of STL-
algorithms for CAD-based, inverse engineering of biomaterial replicas of soft tissue organ vasculature
Strontium and zoledronate hydroxyapatites graded composite coatings for bone prostheses
Full text linkBoth strontium and zoledronate (ZOL) are known to be useful for the treatment of bone diseases associated to the loss of bone substance. In this work, we applied an innovative technique, Combinatorial Matrix-Assisted Pulsed Laser Evaporation (C-MAPLE), to deposit gradient thin films with variable compositions of Sr-substituted hydroxyapatite (SrHA) and ZOL modified hydroxyapatite (ZOLHA) on Titanium substrates. Compositional gradients were obtained by simultaneous laser vaporization of the two distinct material targets. The coatings display good crystallinity and granular morphology, which do not vary with composition. Osteoblast-like MG63 cells and human osteoclasts were co-cultured on the thin films up to 21. days. The results show that Sr counteracts the negative effect of relatively high concentration of ZOL on osteoblast viability, whereas both Sr and ZOL enhance extracellular matrix deposition. In particular, ZOL promotes type I collagen production, whereas Sr increases the production of alkaline phosphatase. Moreover, ZOL exerts a greater effect than Sr on osteoprotegerin/RANKL ratio and, as a consequence, on the reduction of osteoclast proliferation and activity. The deposition method allows to modulate the composition of the thin films and hence the promotion of bone growth and the inhibition of bone resorptio
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
(<i>9R</i>)‑9-Hydroxystearate-Functionalized Hydroxyapatite as Antiproliferative and Cytotoxic Agent toward Osteosarcoma Cells.
Full text linkThe possibility to functionalize
calcium phosphates with bioactive
agents is a promising strategy to design innovative biomaterials for
bone repair able to couple the bioactive properties of the inorganic
compounds with the therapeutic effect of the functionalizing agent.
The R enantiomer of the 9-hydroxystearic acid, (<i>9R</i>)-9-HSA, produced from <i>Dimorphotheca sinuata</i> L.
seeds, has proven to act as a natural negative regulator of tumor
cell proliferation. On this basis, hydroxyapatite was synthesized
with increasing contents of (<i>9R</i>)-9-hydroxystearate,
up to ∼8.6 wt %. The incorporation of HSA in the composite
nanocrystals induces a reduction of the crystal mean dimensions and
of the length of the coherently scattering crystalline domains, which
suggest a preferential adsorption onto the hydroxyapatite crystal
faces parallel to the <i>c</i>-axis direction. The composite
nanocrystals were designed so that their cytostatic and cytotoxic
effects toward osteosarcoma cells were modulated by hydroxystearate
content. In fact, results of in vitro tests show that the presence
of HSA in the composite nanocrystals provokes a significant decrease
in SaOS2 osteosarcoma cells proliferation and viability as well as
an increase in lactate dehydrogenase, tumor necrosis factor α,
and caspase 3 levels, with a cytotoxic effect increasing with HSA
content in the nanocrystals
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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