1,720,980 research outputs found
Controlling the Adipose-derived Stem cell 3D-organization on micrometric PLGA regular scaffolds for cardiac tissue regeneration and repair
No full textThe deposition of cells at sites of injury is a clinically relevant approach to facilitate local tissue regeneration and repair. However, cell engraftment, retention, and survival are generally modest, requiring the development of novel deposition techniques and biomaterials. Here, a micro-sized polymeric network (microMESH) is investigated as a promising biodegradable scaffold for the engraftment and tissue integration of human Adipose-Derived Stem Cells (hADSCs) to be used for a wide range of injuries, including myocardial infarction. microMESH comprises a regular network of PLGA microfilaments spatially organized to form square openings of 5x5, 10x10 and 20x20 μm2 . microMESH is realized using soft lithographic techniques starting from a master silicon template reproducing the actual geometry of the final PLGA network. After extensive geometrical, physico-chemical, and mechanical characterizations using a broad range of techniques, hADSCs were integrated with microMESH. Cell viability, spatial organization, secretome and stemness were characterized for all three different microMESH configurations and compared to conventional systems, including 2D plastic dishes and collagen layers. Interestingly, when hADSCs were cultured on microMESH they organized in spheroidal-like structures, despite the geometry, maintaining viability over time. This peculiar attitude of the microMESH to form assemblies better represents the human tissue outside the body, compared to 2D monolayer cultures. Additionally, spheroids established an intimate interaction with the microMESH resulting in the scaffold incorporation within the 3D arrangement formed by the cells. On the contrary, hADSCs form only superficial interaction above the flat collagen sheet that is currently used for cell transplantation in animal models of cardiac diseases. Moreover, once the hADSCs are placed on microMESH, the actin cytoskeleton reorganizes to confer a 3D cell shape with multidirectional actin arrangements, forming nonlinear structures and ring structures at the anchorage site to the microMESH, relative to linear filaments when the cells adhered and flattened onto the plastic surface and on top of collagen scaffold. This internal reorganization and the stronger interaction may explain why microMESH scaffold fostered the secretion of biologically active molecules, acting in a paracrine fashion on resident cells, which are expected to accelerate tissue regeneration and repair. Specifically, when hADSCs grew on microMESH we observed a trend for higher production of several factors with specific implications in angiogenesis, stem cell proliferation and expansion, cell survival, inflammation modulation, ECM remodeling, stem cell mobilization, chemotaxis and homing, relative to 2D monolayer conditions. The paracrine effect of hADSCs is scaffold dependent and can be modulated by tailoring the geometrical and mechanical properties of microMESH. Indeed, the 5x5 microMESH showed its contribution in angiogenesis, ECM remodeling and stem cell mobilization from bone marrow into the bloodstream. Indeed, highest amounts of VEGF, TIMP-2 and GCSF, respectively were detected in 5x5 geometry compared to the other conditions. Rather, 10x10 geometry promotes angiogenesis enhancing the VEGF production, stem cell proliferation and survival by raising the Fibroblast Growth Factors family secretion and EGF factor, respectively and favors ECM remodeling increasing the TIMP-2 production compared to other conditions. Lastly, the 20x20 seems to have a more anti-inflammatory role (combination of IL-10 and TGF-β1) and chemotactic function (e.g. RANTES). Finally, in this work, we started to shed new light on the ability of micromMESH geometry to modulate the hADSCs stemness evaluating the expression levels of CD44, CD90 and CD105 markers over time. The proposed microMESH scaffold is expected to provide an effective alternative to more conventional hADSCs transplant techniques
Assessment of the health status of the clam Chamelea gallina along a latitudinal gradient in the Adriatic Sea
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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
Phytoplankton communities in the northwestern Adriatic Sea: Interdecadal variability over a 30-years period (1988–2016) and relationships with meteoclimatic drivers
Full text linkIn this study the interannual variability of phytoplankton over a ~30-years period in the coastal site of LTER-Senigallia transect (N Adriatic Sea) was investigated to document patterns potentially related to environmental/climatic drivers. Comparing physical and chemical data of the periods 1988–2002 and 2007–2016 periods, we showed that phytoplankton abundance and biomass and inorganic nutrient concentrations increased in the last decade, indicating that the tendency to oligotrophication due to the drop of the Po River outflow in the years 2002–2007 was reversed in the period 2007–2016. The typical P-limited conditions of the N Adriatic Sea seem to have been attenuated in the study area. P levels were not explained by the P concentrations in the Po River waters, suggesting the possible influence of other local P sources that could be related to the anomalous meteorological events (intense rainfalls) that took place in the 2007–2016 period. In the last decade, the community structure and seasonality of phytoplankton markedly changed, as highlighted by the different indicator species for each season: the blooms of Skeletonema marinoi shifted from winter to spring. A significant decrease of coccolithophores was observed particularly in winter months in the 2007–2016 period: some indicator species among the most relevant in the 1988–2002 period (such as Emiliania huxleyi in winter, and Syracosphaera pulchra in spring) have lost this role in 2007–2016. Dinoflagellate abundances decreased, except in spring when the occasional proliferation of large sized species caused biomass peaks. The phytoplankton annual cycle became irregular with sudden diatom blooms, reflecting the variability of meteorological events in recent years. It is noteworthy that in the last decade, an allochthonous species, i.e. the diatom Pseudo-nitzschia multistriata, became a regular inhabitant of the autumn phytoplankton communities of the NW Adriatic Sea
Variability of hydrographic and biogeochemical properties in the North-western Adriatic coastal waters in relation to river discharge and climate changes
No full textThe dynamics of hydrographic and biogeochemical properties in a Northwestern coastal area of the Adriatic Sea were investigated. The time series data from continuous observation (2007–2022) allowed the investigation of annual trends and seasonal cycles along a coastal transect influenced by local river discharge. Various statistical models were used to investigate water temperature, salinity, chlorophyll a, dissolved organic, inorganic and particulate nutrients, precipitation and river discharge. It was found that the local river discharge regime played an essential role in interannual, and seasonal biogeochemical dynamics associated with global climate change in the Mediterranean region. A significant trend towards oligotrophic conditions was detected, as evidenced by the downward trend in the river mouth and on the sea of chlorophyll a (−0.2 μg L−1 in the sea), dissolved organic and inorganic nitrogen and phosphorus (i.e., −0.43 μM yr−1 of DON in the sea and −6.67 of DIN μM yr−1 in the river mouth or −0.07 μM yr−1 of DOP and −0.02 μM yr−1 of DIP in the river mouth) and silicate (−2.47 μM yr−1 in the river mouth) concentrations. Salinity showed a long-term increase in the sea (0.08 yr−1), corresponding to a significant decrease in water discharge from the local river (−0.27 m3 s−1 yr−1) and precipitation (−0.06 mm yr−1). The dissolved organic and inorganic nutrients highlighted a different seasonal accumulation under the river runoff regime. The nutrient enrichment was predominantly driven by river contribution. Data analysis showed that the coastal biogeochemical properties dynamics were mostly influenced by river discharge and precipitation regimes, which in turn are driven by climate change variability in the North-western Adriatic Sea
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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