1,720,963 research outputs found
Chemically crosslinked gelatin hydrogels as scaffolding materials for adipose tissue engineering
No full textThe design of scaffolding materials that mimic the properties of the target tissue to be regenerated is a mandatory requirement to engineer a successful scaffold; however, the heterogeneous properties of adipose tissue (AT), strictly dependent on the AT depot, are often underestimated when engineering AT scaffolds. Moreover, a scaffolding material with versatile properties, suitable for the regeneration of different AT depots, is currently missing. Chemically crosslinked gelatin hydrogels are here prepared, and their properties tuned by varying gelatin concentration and reaction stoichiometry to obtain hydrogels suitable for AT regeneration. All hydrogel formulations are stable in water at 37 °C, showing swelling behavior dependent on synthesis parameters. The mechanical compressive response mimics the viscoelastic response typical of native AT, with elastic modulus values covering the range of breast and heel pad AT. The rheological properties vary among the hydrogel formulations, showing a typical shear thinning response, comparable to other AT scaffolds described in literature. In vitro cytotoxicity tests using 3T3-L1 preadipocytes show no cytotoxic effects up to 7 days. 3T3-L1 cells seeded on the hydrogels show good adhesion, proliferation, and adipogenic differentiation, confirmed by an increase in peroxisome proliferator-activated receptor gamma gene expression and lipid droplets accumulation observed by Oil Red O staining. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47104
Graphene oxide (GO) decorated on multi-structured porous titania fabricated by plasma electrolytic oxidation (PEO) for enhanced antibacterial performance
Full text linkPlasma electrolytic oxidation (PEO) is proven as a scalable method for surface treatment of titanium (Ti) providing a thick oxide layer with porous micro-nano morphology. Despite the lack of antibacterial performance, this modification has potential to improve the osseointegration properties of Ti-based implant. To address this limitation, we demonstrated a new concept, showing that partial incorporation of graphene oxide (GO) to porous-PEO Ti-surface can significantly improve its antibacterial performance. Our idea for partial coating compared with a full surface coverage of GO was motivated to create a mixed surface with porous PEO and GO to improve antibacterial ability, while maintaining the osseointegration properties. To achieve these goals, we combined PEO and electrophoretic deposition process (EPD) to deposit GO sheets over the titanium PEO-treated substrate. The SEM, EDS, optical profilometry, XRD and Raman spectroscopy confirmed the growth of unique multi-structured porous PEO structures decorated with GO patches. The bio-mineralization test provided the evidence of hydroxyapatite formation over the PEO-GO surface, indicating its good bioactivity. Finally, PEO-GO samples demonstrated a superior antibacterial rate of ~80% against E.coli and ~100% against S. aureus. These results indicate that PEO-GO modified titanium substrates are very promising for the development of advanced biomedical implants
N-Hydroxyphthalimide catalysts as bioactive pro-oxidants
No full textThe catalytic role of N-hydroxyphthalimide (NHPI) in promoting free-radical hydrogen atom transfer (HAT) reactions, well-documented for processes of industrial and synthetic interest, is here investigated for the first time in a biological environment. While NHPI by itself did not show any bioactivity, selected NHPI-derivatives (NHPIDs) revealed the ability to activate the intracellular formation of reactive oxygen species (ROS), causing the depletion of glutathione (GSH) levels and an increase in oxidative stress (OS). The evident bioactivity of some of these derivatives resulted in a significant reduction of the viability in osteosarcoma MG-63, suggesting a new, potential role of NHPIDs as pro-oxidant drugs. The key role of the N–OH group in promoting oxidative stress is demonstrated
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
Immunogenicity of the ALLAVGATK (gp100(17-25)) peptide in HLA-A3.1 melanoma patients
No full textA T cell line recognizing autologous and allogeneic HLA-A3.1 melanomas was obtained from a disease-free melanoma patient (patient 15392). By transfection of a tumor cDNA library and in vitro sensitization experiments, the ALLAVGATK gp100/Mel17-derived peptide was found to be the epitope recognized by this melanoma-specific T cell line. The role of the ALLAVGATK peptide in the systemic immune response to melanoma of this patient was evaluated. When pulsed on the autologous peripheral blood mononuclear cells, the ALLAVGATK peptide generated tumor-specific HLA-AS-restricted T lymphocytes and a single restimulation in vitro was sufficient to raise gp100-specific T lymphocytes, indicating a high frequency of epitope-specific T cells. gp100-specific T cells were also induced from T lymphocytes purified from tumor-invaded lymph nodes (tumor-associated lymphocytes, TAL). TAL-derived effecters displayed lower peptide affinity and lower tumor recognition than effecters elicited from peripheral blood lymphocytes (PBL). To further evaluate its immunogenicity, ALLAVGATK was used to stimulate PBL derived from six additional HLA-A3.1 melanoma patients and seven healthy donors. After 7 weeks of peptide stimulation in vitro the generation of anti-gp100 and tumor-specific T cell lines was achieved in one out of the six patients analyzed. Taken together these data indicate that an in vivo priming leading to a systemic immunity against gp100 in HLA-A3 melanoma patients may occasionally occur and that the immunogenicity of ALLAVGATK peptide in melanoma patients is comparable to that of other HLA-A2-restricted epitopes derived from gp100/Mel 17 protein
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