1,721,022 research outputs found
Hautvillers (Marne). L'abbaye.
No full textBousquet-Chevallier Pascale. Hautvillers (Marne). L'abbaye. . In: Archéologie médiévale, tome 19, 1989. p. 292
Hautvillers (Marne). L'abbaye.
No full textBousquet-Chevallier Pascale. Hautvillers (Marne). L'abbaye. . In: Archéologie médiévale, tome 21, 1991. p. 311
Reims (Marne). Ancienne église Saint-Julien
No full textBousquet-Chevallier Pascale. Reims (Marne). Ancienne église Saint-Julien. In: Archéologie médiévale, tome 23, 1993. p. 391
Reims (Marne). Ancienne église Saint-Julien
No full textBousquet-Chevallier Pascale. Reims (Marne). Ancienne église Saint-Julien. In: Archéologie médiévale, tome 23, 1993. p. 391
La crypte de l'Abbaye de la Sainte Trinité de Cava de' Tirreni (Salerne): état actuel et lignes de recherche.
No full textIl contributo illustra lo stato attuale della cripta della chiesa della millenaria Abbazia della SS. Trinità di Cava dei Tirreni, che rappresenta, con buona verosimiglianza, il nucleo più antico dell'insediamento eremitico. Partendo dall'edito e dalle sopravvivenze architettoniche, molto rimaneggiate nei secoli e adattate alle mutate esigenze della comunità, si indicano le strutture probabilmente riconducibili alle prime fasi e si indicano possibili linee di ricerca, che potrebbero essere seguite utilmente con l'ausilio di tecniche di prospezione non invasiva e con analisi archeometriche
Biomimetic coating of cross-linked gelatin to improve mechanical and biological properties of electrospun PET: A promising approach for small caliber vascular graft applications
No full textElectrospun PET (ePET) is a promising material for small caliber vascular graft applications owing to its tunable mechanical properties, biocompatibility, and nanofibrous structure that mimic the morphology of natural extracellular matrix. However, the inherent inertness of PET impairs the adhesion and proliferation of endothelial cells on the inner surface of ePET tubular grafts, hindering the formation of a functional endothelium. Gelatin coatings, owing to their ability to promote endothelialization, are a valuable approach to overcome the limitations of ePET. Herein, a novel process for the deposition of stable biomimetic coatings of gelatin on ePET tubular grafts is proposed. Electrospun PET was first aminated by plasma treatment and then coated with a gelatin hydrogel cross-linked in situ by a Michael-type addition reaction. Amination provided a superhydrophilic behavior to the ePET surface, allowing easy gelatin interpenetration along the wall thickness of the tubular structure, and the obtainment of thin coatings that maintained the morphology of ePET fibers. Gelatin coating was stable at long term in a physiological-like environment, noncytotoxic and promoted in vitro cell adhesion and proliferation. Noteworthy, the mechanical properties of gelatin-coated ePET tubular grafts were improved in terms of elastic modulus, compliance, and elastic recoil, finally better matching the characteristics of native blood vessels. Altogether, the proposed coating technique successfully combines the advantages of ePET nanofibrous structure with cross-linked gelatin biological cues and mechanical reinforcement, and emerges as a promising strategy for the development of biocompatible small caliber vascular grafts with superior biomimetic and mechanical properties. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2405â2415, 2017
Enabling 3D bioprinting of cell-laden pure collagen scaffolds via tannic acid supporting bath
Full text linkThe fabrication of cell-laden biomimetic scaffolds represents a pillar of tissue engineering and regenerative medicine (TERM) strategies, and collagen is the gold standard matrix for cells to be. In the recent years, extrusion 3D bioprinting introduced new possibilities to increase collagen scaffold performances thanks to the precision, reproducibility, and spatial control. However, the design of pure collagen bioinks represents a challenge, due to the low storage modulus and the long gelation time, which strongly impede the extrusion of a collagen filament and the retention of the desired shape post-printing. In this study, the tannic acid-mediated crosslinking of the outer layer of collagen is proposed as strategy to enable collagen filament extrusion. For this purpose, a tannic acid solution has been used as supporting bath to act exclusively as external crosslinker during the printing process, while allowing the pH- and temperature-driven formation of collagen fibers within the core. Collagen hydrogels (concentration 2–6 mg/mL) were extruded in tannic acid solutions (concentration 5–20 mg/mL). Results proved that external interaction of collagen with tannic acid during 3D printing enables filament extrusion without affecting the bulk properties of the scaffold. The temporary collagen-tannic acid interaction resulted in the formation of a membrane-like external layer that protected the core, where collagen could freely arrange in fibers. The precision of the printed shapes was affected by both tannic acid concentration and needle diameter and can thus be tuned. Altogether, results shown in this study proved that tannic acid bath enables collagen bioprinting, preserves collagen morphology, and allows the manufacture of a cell-laden pure collagen scaffold
Methanol plasma treatment of fluorocarbon ultra-thin films for stents applications
No full textThe surgical implantation of metallic stents in a narrowed vessel after balloon angioplasty is a common procedure to prevent restenosis phenomena, but the related complications, such as thrombosis, inflammation and devices corrosion, are still a serious concern.
In order to limit those complications, the coating of metallic stents, by Plasma Enhanced Chemical Vapor Deposition (PECVD), with Fluorocarbon (CFx) ultrathin films has been demonstrated to be an interesting strategy, thanks to the CFx biocompatibility, chemical inertness, impermeability, corrosion resistance, appropriate mechanical properties and high adhesion to the substrates[1],[2].
Nevertheless, the modification of some key surface properties of CFx coatings could further improve their blood compatibility. For example, it has been shown that the presence of carboxyl groups and a moderate surface wettability could promote the appropriate proteins adhesion, improving the hemocompatibility and promoting the surface endothelialisation[3],[4].
The objective of this work was to develop an oxidation process of CFx coatings, based on a methanol plasma treatment. The modification of the surface oxygen content and wettability was aimed to modulatie protein adsorption and blood compatibility of CFx films, without affecting their excellent mechanical and corrosion resistance properties
Heparin-Modified Collagen Gels for Controlled Release of Pleiotrophin: Potential for Vascular Applications
No full textA fast re-endothelialization, along with the inhibition of neointima hyperplasia, are crucial to reduce the failure of vascular bypass grafts. Implants modifications with molecules capable of speeding up the re-endothelialization process have been proposed over the last years. However, clinical trials of angiogenic factor delivery have been mostly disappointing, underscoring the need to investigate a wider array of angiogenic factors. In this work, a drug release system based on a type I collagen hydrogel has been proposed for the controlled release of Pleiotrophin (PTN), a cytokine known for its pro-angiogenetic effects. Heparin, in virtue of its ability to sequester, protect and release growth factors, has been used to better control the release of PTN. Performances of the PTN drug delivery system on endothelial (ECs) and smooth muscle cells (SMCs) have been investigated. Structural characterization (mechanical tests and immunofluorescent analyses of the collagen fibers) was performed on the gels to assess if heparin caused changes in their mechanical behavior. The release of PTN from the different gel formulations has been analyzed using a PTN-specific ELISA assay. Cell viability was evaluated with the Alamar Blue Cell Viability Assay on cells directly seeded on the gels (direct test) and on cells incubated with supernatant, containing the released PTN, obtained from the gels (indirect test). The effects of the different gels on the migration of both ECs and SMCs have been evaluated using a Transwell migration assay. Hemocompatibility of the gel has been assessed with a clotting/hemolysis test. Structural analyses showed that heparin did not change the structural behavior of the collagen gels. ELISA quantification demonstrated that heparin induced a constant release of PTN over time compared to other conditions. Both direct and indirect viability assays showed an increase in ECs viability while no effects were noted on SMCs. Cell migration results evidenced that the heparin/PTN-modified gels significantly increased ECs migration and decreased the SMCs one. Finally, heparin significantly increased the hemocompatibility of the collagen gels. In conclusion, the PTN-heparin-modified collagen here proposed can represent an added value for vascular medicine, able to ameliorate the biological performance, and integration of vascular grafts
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