1,720,994 research outputs found
European Definitions, Current Use, and EMA Stance of Platelet-Rich Plasma in Sports Medicine.
No full textPlatelet-rich plasma has been the focus of much attention over the last few years as an appealing biological approach to favor the healing of tissues otherwise doomed by a low healing potential. In Europe, the regulatory framework concerning the blood system is currently disciplined by Directive 2002/98/EC of the European Parliament and Council of January 27, 2003, which sets out quality and safety rules for collecting, controlling, processing, preserving, and distributing human blood and its components, acknowledged in the various States of the Union with internal regulations. This lack of homogeneity in the European legal landscape will probably lead the Community legislature to intervene in the near future, to even out the "rules of engagement" of this peculiar class of biomaterials
Stem cells in articular cartilage regeneration
Full text linkMesenchymal stem cells (MSCs) have emerged as a promising option to treat articular defects and early osteoarthritis (OA) stages. However, both their potential and limitations for a clinical use remain controversial. Thus, the aim of this systematic review was to examine MSCs treatment strategies in clinical settings, in order to summarize the current evidence of their efficacy for the treatment of cartilage lesions and OA.Among the 60 selected studies, 7 were randomized, 13 comparative, 31 case series, and 9 case reports; 26 studies reported the results after injective administration, whereas 33 used surgical implantation. One study compared the two different modalities. With regard to the cell source, 20 studies concerned BMSCs, 17 ADSCs, 16 BMC, 5 PBSCs, 1 SDSCs, and 1 compared BMC versus PBSCs. Overall, despite the increasing literature on this topic, the evidence is still limited, in particular for high-level studies. On the other hand, the available studies allow to draw some indications. First, no major adverse events related to the treatment or to the cell harvest have been reported. Second, a clinical benefit of using MSCs therapies has been reported in most of the studies, regardless of cell source, indication, or administration method. This effectiveness has been reflected by clinical improvements and also positive MRI and macroscopic findings, whereas histologic features gave more controversial results among different studies. Third, young age, lower BMI, smaller lesion size for focal lesions, and earlier stages of OA joints have been shown to correlate with better outcomes, even though the available data strength does not allow to define clear cutoff values. Finally, definite trends can be observed with regard to the delivery method: currently cultured cells are mostly being administered by i.a. injection, while one-step surgical implantation is preferred for cell concentrates. In conclusion, while promising results have been shown, the potential of these treatments should be confirmed by reliable clinical data through double-blind, controlled, prospective and multicenter studies with longer follow-up, and specific studies should be designed to identify the best cell sources, manipulation, and delivery techniques, as well as pathology and disease phase indications
Teachers in a Searchable World:Findings from an Introductory Survey
Full text linkIn this manuscript, we discuss the findings from an introductory survey conducted with more than 50 teachers in Italy. We inquired about teachers’ opinions of educational technology used in the classroom, in particular search tools. Qualitative and quantitative data inferred from collected responses provide us with a multifaceted picture of the different roles teachers perform in the classroom when interacting with technology, their preferences, skills, perceptions of the needs for training, in addition to the principles and motivations that guide them. Findings emerging from this survey serve as a foundation for an international study that would allow us to better model teachers’ needs and the barriers they face when using search tools in the classroom.</p
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
Prp with or without leukocytes: any difference on chondrocytes and synoviocytes culture?
No full textObjectives: Platelet Rich Plasma (PRP) is a biological compound rich
of growth factors able to support healing processes, and it represents a
fascinating tool for clinicians. However results on its potentiality as
intra-articular treatment for cartilage degenerative lesions in osteoarthritis
(OA) are still controversial, due to the lack of well designed
studies and the differences in the preparation procedures. The aim of
this study was to analyze the modifications induced by two different
PRP preparations on chondrocytes and sinoviocytes in culture, by
documenting changes in proliferations, gene expression, and extracellular
matrix components deposition.
Methods: Blood collected from 10 volunteers was used to obtain two
PRP preparations derived respectively from a ‘‘one-spinning procedure’’,
to obtain a pure platelet concentrate without leukocytes but
with a limited number of platelets (P-PRP), and by a ‘‘two-spinning
approach’’, producing a product characterized by a higher platelet
concentration and the presence of leukocytes (L-PRP).
Results: Our data showed that L-PRP contains higher levels of growth
factors and cytokines compared to P-PRP. Both PRPs stimulate
chondrocytes proliferation during all the culture period evaluated; a
significant enhancement in cell growth was induced by P-PRP respect
to L-PRP only at day 7. Moreover, P-PRP stimulates chondrocyte
anabolism as demonstrated by the expression of collagen type II and aggrecan, while L-PRP promotes catabolic pathways in which some
different cytokines are involved. Interesting, L-PRP induces a higher
expression of hyaluronic acid synthase-2 and hyaluronan compared to
P-PRP. On sinoviocytes, L-PRP is able to sustain the up-regulation of
proinflammatory factors, such as IL-1beta, IL-8 and FGF-2, together
with a down modulation of HGF and TIMP-4 expression, two factors
that have been recognized as anti-catabolic mediators in cartilage,
whereas P-PRP was not able to exert a differential pattern of biological
effect compared to PPP.
Conclusions: Our study highlights that the two PRPs induce distinct
effects on cultured human chondrocytes and sinoviocytes. This is due
to the different content in PRP of platelets, leukocytes, growth factors
and molecules that act synergically to regulate several biological
processes which could influence the regeneration of a functional
tissue
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
Platelet-Rich Plasma: The Choice of Activation Method Affects the Release of Bioactive Molecules
Full text linkPlatelet-Rich Plasma (PRP) is a low-cost procedure to deliver high concentrations of autologous growth factors (GFs). Platelet activation is a crucial step that might influence the availability of bioactive molecules and therefore tissue healing. Activation of PRP from ten voluntary healthy males was performed by adding 10% of CaCl2, 10% of autologous thrombin, 10% of a mixture of CaCl2 + thrombin, and 10% of collagen type I. Blood derivatives were incubated for 15 and 30 minutes and 1, 2, and 24 hours and samples were evaluated for the release of VEGF, TGF-β1, PDGF-AB, IL-1β, and TNF-α. PRP activated with CaCl2, thrombin, and CaCl2/thrombin formed clots detected from the 15-minute evaluation, whereas in collagen-type-I-activated samples no clot formation was noticed. Collagen type I produced an overall lower GF release. Thrombin, CaCl2/thrombin, and collagen type I activated PRPs showed an immediate release of PDGF and TGF- β 1 that remained stable over time, whereas VEGF showed an increasing trend from 15 minutes up to 24 hours. CaCl2 induced a progressive release of GFs from 15 minutes and increasing up to 24 hours. The method chosen to activate PRP influences both its physical form and the releasate in terms of GF amount and release kinetic
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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