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Sökning: L773:1549 3296 OR L773:1552 4965 > Lunds universitet

  • Resultat 1-10 av 17
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1.
  • Bjursten, Lars Magnus, et al. (författare)
  • Titanium dioxide nanotubes enhance bone bonding in vivo.
  • 2010
  • Ingår i: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 92:3, s. 1218-24
  • Tidskriftsartikel (refereegranskat)abstract
    • Implant topography is critical to the clinical success of bone-anchored implants, yet little is known how nano-modified implant topography affects osseointegration. We investigate the in vivo bone bonding of two titanium implant surfaces: titanium dioxide (TiO(2)) nanotubes and TiO(2) gritblasted surfaces. In previous in vitro studies, the topography of the TiO(2) nanotubes improved osteoblast proliferation and adhesion compared with gritblasted titanium surfaces. After four weeks of implantation in rabbit tibias, pull-out testing indicated that TiO(2) nanotubes significantly improved bone bonding strength by as much as nine-fold compared with TiO(2) gritblasted surfaces. Histological analysis confirmed greater bone-implant contact area, new bone formation, and calcium and phosphorus levels on the nanotube surfaces. It is anticipated that further studies will contribute to a better understanding of the effect of implant nanotopography on in vivo bone formation and bonding strength.
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2.
  • Bloch, K, et al. (författare)
  • Functional activity of insulinoma cells (INS-1E) and pancreatic islets cultured in agarose cryogel sponges
  • 2005
  • Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 75A:4, s. 802-809
  • Tidskriftsartikel (refereegranskat)abstract
    • Here, we describe the preparation, structure, and properties of cryogel sponges, which represent a new type of macroporous biomaterial for tissue engineering. Cryogels were produced through freeze-thawing techniques, either from agarose alone or from agarose with grafted gelatin. The aim of this study was to evaluate agarose cryogel sponges as scaffolds for Culturing both isolated pancreatic islets and insulinoma cells (INS-IE). In order to evaluate the effect of cell entrapment in artificial scaffolds, cell function reflected by insulin secretion and content was studied in cells cultivated for a 2-week period either in Culture plastic plates or in cryogel sponge disks. Our results show that tumor-derived INS-1E cells grown either on plastic or on cryogels do not differ in their proliferation, morphology, insulin release, and intracellular insulin content. However, isolated pancreatic islets cultivated on cryogels sponge show 15-fold higher basal insulin secretion at 3.0 mM glucose than islets cultivated on plastic plates and fail to respond to stimulation with 16.7 mM glucose. In addition, these islets have about 2-fold lower insulin content compared to those grown in plastic plates. It is possible that the cell dysfunction noted in these in vitro experiments is due to the effect of the limited oxygen supply to the islets cultivated in cryogel sponge. Further in vivo Studies are needed to clarify the nature of such an observation since according to previous reports, agarose and gelatin induce new vessel formation supporting enhanced oxygen supply. (c) 2005 Wiley Periodicals, Inc.
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3.
  • Bolgen, Nimet, et al. (författare)
  • Tissue responses to novel tissue engineering biodegradable cryogel scaffolds: An animal model
  • 2009
  • Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 91A:1, s. 60-68
  • Tidskriftsartikel (refereegranskat)abstract
    • Biodegradable macroporous cryogels with highly open and interconnected pore structures were produced from dextran modified with oligo L-lactide bearing hydroxyethylmethacrylate (HEMA) end groups in moderately frozen solutions. Tissue responses to these novel scaffolds were evaluated in rats after dorsal subcutaneous implantation, iliac submuscular implantation, auricular implantation, or in calvarial defect model. In no case, either necrosis or foreign body reaction was observed during histological studies. The cryogel scaffolds integrated with the surrounding tissue and the formation of a new tissue were accompanied with significant ingrowth of connective tissue cells and new blood vessels into the cryogel. The tissue responses were significantly lower in auricular and calvarial implantations when compared with the subcutanous and the submuscular implantations. The degradation of the scaffold was slower in bone comparing to soft tissues. The biodegradable cryogels are highly biocompatible and combine extraordinary properties including having soft and elastic nature, open porous structure, and very rapid and controllable swelling. Therefore, the cryogels could be promising candidates for further clinical applications in tissue regeneration. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 91 A: 60-68, 2009
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4.
  • Ivanov, Alexander, et al. (författare)
  • Boronate-containing polymer brushes: Characterization, interaction with saccharides and mammalian cancer cells.
  • 2009
  • Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 88:1, s. 213-225
  • Tidskriftsartikel (refereegranskat)abstract
    • Boronate-containing polymer brushes were synthesized by free radical copolymerization of N,N-dimethylacrylamide (DMAA) and N-acryloyl-m-phenylboronic acid (NAAPBA) (9:1) on the surface of 3-mercaptopropyl-silylated glass plates and capillaries. The brushes were characterized with time-of-flight secondary ion mass-spectrometry (ToF SIMS), atomic force microscopy and contact angle measurements. Fructose caused a well-expressed drop spreading on the surface of copolymer-grafted glass, due to the strong interaction with the boronate groups. Sedimentation of murine hybridoma cells M2139 or human myeloid leukemia cells KG1 onto the DMAA-NAAPBA copolymer-grafted glass plates from 10 mM phosphate buffer solution (pH 8.0) resulted in the cell adhesion. The adhered M2139 and KG1 cells could be quantitatively detached from the grafted plates with 0.1M fructose, which competed with cell surface carbohydrates for binding to the boronates. Evaluation of the binding strength between M2139 cells and the copolymer brush was performed by exposure of the adhered cells to a shear stress. Detachment of a fraction of 18% of the adhered M2139 cells was obtained at a shear force of 1400-2800 pN/cell generated by the running phosphate buffer (pH 8.0), whereas the remaining adhered cells (70%) could be detached with 0.1M fructose dissolved in the same buffer. Possible applications of the boronate-containing polymer brushes to affinity cell separation can be based upon the facile recovery of the attached cells. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2008.
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5.
  • Laschke, MW, et al. (författare)
  • New experimental approach to study host tissue response to surgical mesh materials in vivo
  • 2005
  • Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 74A:4, s. 696-704
  • Tidskriftsartikel (refereegranskat)abstract
    • Implantation of surgical meshes is a common procedure to increase abdominal wall stability in hernia repair. To improve biocompatibility of the implants, sophisticated in vivo animal models are needed to study inflammation and incorporation of biomaterials. Herein, we have established a new model that allows for the quantitative analysis of host tissue response and vascular ingrowth into surgical mesh materials in vivo. Ultrapro meshes were implanted into dorsal skinfold chambers of Syrian golden hamsters. Angiogenesis, microhemodynamics, microvascular permeability, and leukocyte-endothelial cell interaction of the host tissue were analyzed in response to material implantation over a 2-week period using intravital fluorescence microscopy. Mesh implantation resulted in a short-term activation of leukocytes, reflected by leukocyte accumulation and adherence in postcapillary venules. This cellular inflammatory response was accompanied by an increase of mac-romolecular leakage, indicating loss of integrity of venular endothelial cells. Angiogenesis started at day 3 after implantation by protrusion of capillary sprouts, originating from the host microvasculature. Until day 10, these sprouts interconnected with each other to form a new microvascular network. At day 14, the inflammatory response had disappeared and the vascular ingrowth was completed. Histology confirmed the formation of granulation tissue with adequate incorporation of the mesh filaments within the host tissue. We conclude that this novel model of surgical mesh implantation is a useful experimental approach to analyze host tissue response and vascular ingrowth of newly devised materials for hernia repair.
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6.
  • McGillicuddy, F. C., et al. (författare)
  • Novel "plum pudding" as potential drug-eluting stent coatings : Controlled release of fluvastatin
  • 2006
  • Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 79A:4, s. 923-933
  • Tidskriftsartikel (refereegranskat)abstract
    • This study evaluated novel structural motifs known as "plum pudding" gels as potential drug-eluting stent coatings. Controlled delivery of a HMG-CoA reductase inhibitor (statin) from the intravascular stent surface represents a potential therapeutic modality for prevention of in-stent restenosis (ISR). In this study, gels were comprised of fluvastatin-loaded thermoresponsive microgel particles containing the relatively hydrophilic N-isopropyl-acrylamide (NiPAAm), mixed with the more hydrophobic N-tert-butylacrylamide (NtBAAm) in different wt/wt ratios: 85/15, 65/35, and 50/50, randomly dispersed in a 65/35 or 85/15 NiPAAm/NtBAAm copolymer matrix. Fluvastatin release from 5 mu m copolymer films was greatest from the most hydrophilic systems and least from the more hydrophobic systems. Release from hydrophobic matrices appeared to be via Fickian diffusion, enabling use of the Stokes-Einstein equation to determine diffusion coefficients. Release from hydrophilic matrices was nonFickian. Fluted drug retained its bioactivity, assessed as selective inhibition of human coronary artery smooth muscle cell proliferation. When stainless steel stent wires were coated (25 mu m thickness) with fluvastatin-loaded 65/35 microgels in an 85/15 copolymer matrix, drug elution into static and perfused flow environments followed similar elution profiles. In contrast to elution from copolymer films cast on flat surfaces, diffusion from stent wires coated with hydrophilic and hydrophobic systems both followed Fickian patterns, with slightly larger diffusion coefficients for elution from the flow system. We conclude that manipulation of the relative hydrophobicities of both microgel and matrix components of "plum pudding" gels results in tightly regulated release of fluvastatin over an extended time period relevant to initiation and propagation of ISR. (c) 2006 Wiley Periodicals, Inc.
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8.
  • Sahlin, Herman, et al. (författare)
  • Anti-inflammatory properties of micropatterned titanium coatings
  • 2006
  • Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 77A:1, s. 43-49
  • Tidskriftsartikel (refereegranskat)abstract
    • Prolonged inflammation and reactive oxygen species (ROS) generated around an implanted biosensor are the primary causes of the foreign body response, including encapsulation of biosensor membranes. We have previously demonstrated that TiO2 surfaces reduce ROS. Here we investigated the potential of using the anti-inflammatory properties of TiO2 in the design of biosensor membranes with improved long-term in vivo transport properties. Micropatterned Ti films were sputtered onto quartz surfaces in a series of hexagonally distributed dots with identical coverage area of 23% and dot size ranging from 5 to 100 microm. The antioxidant effect of the surfaces was investigated using a cell-free peroxynitrite donor assay and assays of superoxide released from stimulated surface-adhering neutrophils and macrophages. In all three assays, the amount of ROS was monitored using luminol-amplified chemiluminescence. Patterned surfaces in all experimental models significantly decreased ROS compared to the etched surfaces. In the cell-free experiment, the ROS reduction was only dependent on fractional surface coverage. In the cell experiments, however, a dot-size-dependent ROS reduction was seen, with the largest reduction at the smallest dot-size surfaces. These results indicate that micropatterned surfaces with small dots covering only 23% of the surface area exhibit similar antioxidative effect as fully covered surfaces.
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9.
  • Bettini, Giovanni, et al. (författare)
  • Sand Waves and Human Tides: Exploring Environmental Myths on Desertification and Climate-Induced Migration
  • 2014
  • Ingår i: The Journal of Environment & Development. - : SAGE Publications. - 1552-5465 .- 1070-4965. ; 23:1, s. 160-185
  • Tidskriftsartikel (refereegranskat)abstract
    • In spite of the growing attention to climate-induced migration, a coherent understanding of the matter is lackingas any articulated governance strategy. Although such an impasse relates to the unprecedented socioecological processes involved, we argue that many of the challenges posed by climate-induced migration are not unique in the history of global environmental governance. Proceeding from this, we compare climate migration with the issue of desertification. Drawing upon the concept of environmental myth developed in Political Ecology, we identify common themes such as scientism, vagueness, and ambiguities in the definitions, and a tendency to envision one-fits-all solutions that overlook the multiscalar phenomena involved. We discuss how these traits have contributed to the failure of the desertification regime. Consequently, we propose that climate migration debates should move beyond such deficiencies, to avoid the consolidation of policy responses reproducing the same problems that have characterized the regime on desertification.
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10.
  • Duit, Andreas, et al. (författare)
  • Saving the Woodpeckers : Social Capital, Governance, and Policy Performance
  • 2009
  • Ingår i: Journal of Environment and Development. - : SAGE Publications. - 1070-4965 .- 1552-5465. ; 18:1, s. 42-61
  • Tidskriftsartikel (refereegranskat)abstract
    • This article investigates if higher levels of social capital,better governance structures, and a more ambitious conservationpolicy are positively linked to the ability of states to addressbiodiversity loss. Serving this purpose is a data set containingestimates of woodpecker diversity in 20 European countries.These data are argued to be a more valid indicator of biodiversitythan most other available cross-national measures of environmentalquality. A seemingly unrelated regression analysis reveals thatnone of the indicators are linked to higher levels of woodpeckerdiversity, which in turn leads to the conclusion that presentinstitutions, environmental policies, and social structureshave negligible effects on biodiversity compared to long-termlandscape transformations.
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