| 1. |
- Ghane, Nazanin, et al.
(författare)
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Regeneration of the peripheral nerve via multifunctional electrospun scaffolds
- 2021
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley & Sons. - 1549-3296 .- 1552-4965. ; 109:4, s. 437-452
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Forskningsöversikt (refereegranskat)abstract
- Over the last two decades, electrospun scaffolds have proved to be advantageous in the field of nerve tissue regeneration by connecting the cavity among the proximal and distal nerve stumps growth cones and leading to functional recovery after injury. Multifunctional nanofibrous structure of these scaffolds provides enormous potential by combining the advantages of nano‐scale topography, and biological science. In these structures, selecting the appropriate materials, designing an optimized structure, modifying the surface to enhance biological functions and neurotrophic factors loading, and native cell‐like stem cells should be considered as the essential factors. In this systematic review paper, the fabrication methods for the preparation of aligned nanofibrous scaffolds in yarn or conduit architecture are reviewed. Subsequently, the utilized polymeric materials, including natural, synthetic and blend are presented. Finally, their surface modification techniques, as well as, the recent advances and outcomes of the scaffolds, both in vitro and in vivo, are reviewed and discussed.
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| 2. |
- Han, Yilin, et al.
(författare)
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Effect of scaffold properties on adhesion and maintenance of boundary cap neural crest stem cells in vitro
- 2020
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 108:6, s. 1274-1280
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Tidskriftsartikel (refereegranskat)abstract
- Optimal combination of stem cells and biocompatible support material is a promising strategy for successful tissue engineering. The required differentiation of stem cells is crucial for functionality of engineered tissues and can be regulated by chemical and physical cues. Here we examined how boundary cap neural crest stem cells (bNCSCs) are affected when cultured in the same medium, but on collagen- or laminin-polyacrylamide (PAA) scaffolds of different stiffness (0.5, 1, or similar to 7 kPa). bNCSCs displayed marked differences in their ability to attach, maintain a large cell population and differentiate, depending on scaffold stiffness. These findings show that the design of physical cues is an important parameter to achieve optimal stem cell properties for tissue repair and engineering.
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| 3. |
- Ichioka, Yuki, et al.
(författare)
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Epigenetic changes of osteoblasts in response to titanium surface characteristics.
- 2021
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Ingår i: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 109:2, s. 170-180
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to investigate the influence of titanium surface characteristics on epigenetic mechanisms and DNA damage/repair pathways. Osteoblast-like cells (MG63) were incubated on glass, smooth titanium, and minimally rough titanium discs, respectively, for 0, 1, 6, and 24hr. The presence of double-stranded DNA damage (γH2AX), DNA repair (Chk2), and epigenetic markers (AcH3 & DNMT1) were investigated using immunofluorescence. There were no Chk2-positive cells on the minimally rough titanium surfaces at all-time points, in comparison to glass and smooth titanium. Total γH2AX-positive cells on minimally rough titanium gradually decreased as incubation time increased, on the contrary to smooth titanium. Minimally rough titanium surfaces induced cytoplasmic staining of DNMT1 up to 99% at 24hr. For epigenetic markers related to the DNA damage/repair pathway, minimally rough titanium surfaces showed the lower percentage of AcH3-positive cells compared to glass and smooth titanium surface. The findings in the current study show that titanium surface characteristics indeed influence DNA damage and the DNA repair pathway, including epigenetic factors.
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| 4. |
- Magnusson, Catarina, et al.
(författare)
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Inhibitory effects of orthosilicic acid on osteoclastogenesis in RANKL-stimulated RAW264.7 cells
- 2021
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 109:10, s. 1967-1978
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies have reported on the positive effects of silicon (Si) on bone metabolism, particularly on the stimulatory effects of Si on osteoblast cells and on bone formation. Inhibitory effects of Si on osteoclast formation and bone resorption have also been demonstrated in vitro and are suggested to be mediated indirectly via stromal and osteoblast cells. Direct effects of Si on osteoclasts have been less studied and mostly using soluble Si, but no characterisation of the Si treatment solutions are provided. The aims of the present study were to (a) further investigate the direct inhibitory effects of Si on osteoclastogenesis in RANKL-stimulated RAW264.7 cells, (b) determine at what stage during osteoclastogenesis Si acts upon, and (c) determine if these effects can be attributed to the biologically relevant soluble orthosilicic acid specie. Our results demonstrate that silicon, at 50 mu g/ml (or 1.8 mM), does not affect cell viability but directly inhibits the formation of TRAP+ multinucleated cells and the expression of osteoclast phenotypic genes in RAW264.7 cells. The inhibitory effect of Si was clearly associated with the early stages (first 24 hr) of osteoclastogenesis. Moreover, these effects can be attributed to the soluble orthosilicic acid specie.
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| 5. |
- Rabel, Kerstin, et al.
(författare)
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Analysis of soft tissue integration-supportive cell functions in gingival fibroblasts cultured on 3D printed biomaterials for oral implant-supported prostheses
- 2024
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley and Sons Inc. - 1549-3296 .- 1552-4965.
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Tidskriftsartikel (refereegranskat)abstract
- To date, it is unknown whether 3D printed fixed oral implant-supported prostheses can achieve comparable soft tissue integration (STI) to clinically established subtractively manufactured counterparts. STI is mediated among others by gingival fibroblasts (GFs) and is modulated by biomaterial surface characteristics. Therefore, the aim of the present work was to investigate the GF response of a 3D printed methacrylate photopolymer and a hybrid ceramic-filled methacrylate photopolymer for fixed implant-supported prostheses in the sense of supporting an STI. Subtractively manufactured samples made from methacrylate polymer and hybrid ceramic were evaluated for comparison and samples from yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), comprising well documented biocompatibility, served as control. Surface topography was analyzed by scanning electron microscopy and interferometry, elemental composition by energy-dispersive x-ray spectroscopy, and wettability by contact angle measurement. The response of GFs obtained from five donors was examined in terms of membrane integrity, adhesion, morphogenesis, metabolic activity, and proliferation behavior by a lactate-dehydrogenase assay, fluorescent staining, a resazurin-based assay, and DNA quantification. The results revealed all surfaces were smooth and hydrophilic. GF adhesion, metabolic activity and proliferation were impaired by 3D printed biomaterials compared to subtractively manufactured comparison surfaces and the 3Y-TZP control, whereas membrane integrity was comparable. Within the limits of the present investigation, it was concluded that subtractively manufactured surfaces are superior compared to 3D printed surfaces to support STI. For the development of biologically optimized 3D printable biomaterials, consecutive studies will focus on the improvement of cytocompatibility and the synthesis of STI-relevant extracellular matrix constituents.
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| 6. |
- Weber, Florian, et al.
(författare)
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Characterization of the foreign body response of titanium implants modified with polyphenolic coatings
- 2022
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Ingår i: Journal of Biomedical Materials Research. Part A. - : John Wiley & Sons. - 1549-3296 .- 1552-4965. ; 110:7, s. 1341-1355
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Tidskriftsartikel (refereegranskat)abstract
- The foreign body response is dictating the outcome of wound healing around any implanted materials. Patients who suffer from chronic inflammatory diseases and impaired wound healing often face a higher risk for implant failure. Therefore, functional surfaces need to be developed to improve tissue integration. For this purpose, we evaluated the impact of surface coatings made of antioxidant polyphenolic molecules tannic acid (TA) and pyrogallol (PG) on the host response in human blood. Our results showed that although the polyphenolic surface modifications impact the initial blood protein adsorption compared to Ti, the complement and coagulation systems are triggered. Despite complement activation, monocytes and granulocytes remained inactivated, which was manifested in a low pro-inflammatory cytokine expression. Under oxidative stress, both coatings were able to reduce intracellular reactive oxygen species in human gingival fibroblasts (hGFs). However, no anti-inflammatory effects of polyphenolic coatings could be verified in hGFs stimulated with lipopolysaccharide and IL-1 beta. Although polyphenols reportedly inhibit the NF-kappa B signaling pathway, phosphorylation of NF-kappa B p65 was observed. In conclusion, our results indicated that TA and PG coatings improved the hemocompatibility of titanium surfaces and have the potential to reduce oxidative stress during wound healing.
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| 7. |
- Bachmann-Vargas, Pamela, et al.
(författare)
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Disentangling environmental and development discourses in a peripheral spatial context : the case of the Aysén region, Patagonia, Chile
- 2020
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Ingår i: Journal of Environment and Development. - : Sage Publications. - 1070-4965 .- 1552-5465. ; 29:3, s. 366-390
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Tidskriftsartikel (refereegranskat)abstract
- In places with a predominantly natural heritage, environmental and development discourses are intertwined and often competing. A key dimension is the social construction of socio-spatial relationships, and particularly, the attribution of core and periphery features. In this article, we investigate environmental and development discourses in the peripheral spatial context of the Aysén region of Chile. Three research questions guide the investigation: (a) What are the dominant environmental and development discourses? (b) what are the main synergies and tensions among discourses? and (c) what are the (discursive) implications for (de-)peripheralization? Based on semistructured interviews and secondary sources, we identify six regional discourses on environment and development. Imaginaries of nature, regional development, and economic growth are the common denominators that create synergies and tensions. We conclude that environmental and development discourses play a key role in the transformation of geographic peripheral areas. Discursive synergies can not only reinforce but also counteract tendencies of peripheralization.
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| 8. |
- Gutberlet, Jutta, et al.
(författare)
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Waste Pickers and Their Practices of Insurgency and Environmental Stewardship
- 2021
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Ingår i: Journal of Environment and Development. - : SAGE Publications. - 1070-4965. ; 30:4, s. 369-394
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Tidskriftsartikel (refereegranskat)abstract
- Informed by different grassroots learning and educational practices engaged in waste management, and drawing from the concepts of insurgent citizenship and environ- mental stewardship, we examine the role of waste picker organizations and movements in creating new pathways towards more sustainable environmental waste governance. Two case studies (Argentina and Brazil) demonstrate how waste pickers inform and educate the general public and raise the awareness of socio-environmental questions related to waste management. Different educational practices are used as strategies to confront citizens with their waste: to see waste as a consumption problem, resource, and income source. Our paper draws on grassroots learning (social movement learning and insurgent learning) and education (stewardship) aimed at the transformation of waste practices. We argue that waste pickers play an important role in knowledge production promoting recycling, in landfilling less and recovering more resources. We conclude that waste pickers act as insurgent citizens and also are environmental stewards.
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| 9. |
- Henrysson, Maryna, et al.
(författare)
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The Role of Institutions in Creating Circular Economy Pathways for Regional Development
- 2021
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Ingår i: Journal of Environment and Development. - : SAGE Publications. - 1070-4965 .- 1552-5465. ; :2, s. 127-148
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Tidskriftsartikel (refereegranskat)abstract
- In the past decade, the circular economy has gained attention as a mechanism of transition toward a regenerative, low carbon, and resource-efficient society. As the history of previous radical transformations shows, successful transition toward the circular economy cannot take place without understanding the institutional features of industrial transformations. This article highlights the significance of institutions by placing the circular economy model in the context of the natural resource–based sector and discusses the importance of institutions in regional path development. The article identifies three institutional determinants of both endogenous and directed transformation toward the circular economy model in the regional context: (i) proximity of physical flows and assets, (ii) maturation and diversity of market networks, and (iii) inherent values and patterns of cooperation. This article offers a starting point for future studies of circular economy transitions and the role of institutions as en- abling, as well as at times obstructing transition environments.
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| 10. |
- Isgren, Ellinor, et al.
(författare)
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An Environmental Justice Perspective on Smallholder Pesticide Use in Sub-Saharan Africa
- 2021
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Ingår i: The Journal of Environment & Development. - : SAGE Publications. - 1552-5465 .- 1070-4965. ; 30:1, s. 68-97
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Tidskriftsartikel (refereegranskat)abstract
- Pesticide use is increasing in many parts of sub-Saharan Africa, and many smallholders purchase, handle, and apply toxic pesticides with inadequate equipment, knowledge, and technical support. Through the frame of environmental justice, this literature-based study analyzes characteristics, impacts, and drivers of smallholder pesticide use in sub-Saharan Africa, with particular attention to Uganda as a case. We find that market liberalization, poor regulation enforcement, and persistent neglect of agricultural extension place the burden of risk largely on farmers, while perceived necessity of pesticides and the elusive nature of impacts (especially under conditions of insufficient monitoring) likely delay social mobilization around pesticides. The environmental justice frame, which has seen limited application in smallholder contexts, importantly helps delineate future directions for research and practice. It is particularly effective for redirecting focus from highly limited managerial solutions for “safe use” toward deeper problem drivers and solutions capable of tackling them.
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