1,720,979 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
Unsaturated tertiary arylamines as low toxicity activators in the formulation of biomedical acrylic resins.
No full textTwo unsaturated tertiary aromatic amines, namely acryloyl- (ArcNP) and methacryloyl-N-phenyl piperazine are proposed as potential substitutes of dimetyl-p toluidine (DMPT), in the ''coldt curing of biomedical acrylic resins. The paper give an overview of the results so far obtained with the new compounds, with particular reference to some unpublished data on their efficacy as activators in the MMA/PMMA cold curing, and on their leachability from MMA cured samples.
AcrNP and MNP showed good efficacy as, accelerators, with similar gel times but lightly prolonged setting times in comparison with DMPT; both compounds (AcrNP in particular), produced PMMA-based cements with similar mechanical properties, but less accelerated ageing than DMPT; differently from MNP, AcrNP showed the ability to copolymerize with MMA, and to be hardly leachable from cured PMMA samples. Above all, the last property makes AcrNP preferable to MNP as red-ox activator, and good potential substitute of DMPT
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
HELP (Human Elastin-like Polypeptide) as a key component in matrices for regenerative medicine
No full textGenetically engineered proteins
represent a new promising class of biomaterials that
overcome the disadvantages of naturally derived
biopolymers (potential pathogens transmission, immune
reactions, etc). These engineered macromolecules contain
repeated natural sequence motifs that induce a regular
structure and self-assembly capability. Many recent
examples show the potentiality of application of elastinlike
polypeptides (ELP) for a wide range of biomedical
applications that exploit their features.
This work aims at designing and producing, by
recombinant DNA methodology, a human elastin-like
artificial protein (HELP) as starting material for the
preparation of self-assembled or crosslinked matrices to
be used in regenerative medicine. On the basis of the
VAPGVG sequence (the most structurally regular
occurring region of the human tropoelastin) a synthetic
gene was designed, cloned and expressed in Escherichia
coli. The obtained artificial HELP protein (an eight
block protein polymer, MW » 45000 Da) includes
substrate amino acids (K, lysine and Q, glutamine) for
enzymatic crosslinking
In vitro interactions of biomedical polyurethanes with macrophages and bacterial cells
No full textThree commercial medical-grade polyurethanes (PUs), a poly-ether-urethane (Pellethane), and two poly-carbonate-urethanes, the one aromatic (Bionate) and the other aliphatic (Chronoflex), were tested for macrophages and bacterial cells adhesion, in the presence or absence of adhesive plasma proteins. All the experiments were carried out on PUs films obtained by solvent casting. The wettability of these films was analysed by measuring static contact angles against water. The ability of the selected PUs to adsorb human fibronectin (Fn) and fibrinogen (Fbg) was checked by ELISA with biotin-labelled proteins. All PUs were able to adsorb Fn and Fbg (Fn > Fbg). Fn adsorption was in the order: Pellethane > Chronoflex > Bionate, the highest Fbg adsorption being detected onto Bionate (Bionate > Chronoflex > Pellethane). The human macrophagic line J111, and the two main bacterial strains responsible for infection in humans (Staphylococcus aureus Newman and Staphylococcus epidermidis 14852) were incubated in turn with the three PUs, uncoated or coated with plasma proteins. No macrophage or bacterial adhesion was observed onto uncoated PUs. PUs coated with plasma, Fn or Fbg promoted bacterial adhesion (S. aureus > S. epidermidis), whereas macrophage adhered more onto PUs coated with Fn or plasma. The coating with Fbg did not promote cell adhesion. Pellethane showed the highest macrophage activation (i.e. spreading), followed, in the order, by Bionate and Chronoflex
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
Ability to support cell proliferation and to stimulate MSCs differentiation of polyurethane foams
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