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- Almqvist, Sofia, 1980, et al.
(författare)
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Ex Vivo Study of the Angiogenic Effect of the Extracellular Matrix Protein Amelogenin
- 2008
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Ingår i: Abstract, The 9th New Jersey Symposium on Biomaterials Science and regenerative medicine, New Jersey, USA. ; 29-31 October
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Konferensbidrag (refereegranskat)abstract
- Introduction: Angiogenesis is crucial for wound healing but is often impaired in chronic wounds. The process is dependent on the interaction of endothelial cells and the extracellular matrix (ECM), which is mediated by cell membrane integrins. Amelogenin is an extracellular matrix protein that has been reported to promote formation of granulation tissue and repair of chronic venous leg ulcers and elevate the pro-angiogenic vascular endothelial growth factor in dermal fibroblasts.1-3 This study investigated the effect of amelogenin on angiogenesis in an ex vivo sprouting assay and related the findings to the cell surface integrin expression. Methods: Chick aortic arch assay: Transverse sections of the aortic arch of 13-day-old chick embryos were attached and sealed with Matrigel to the bottom of a 48-well plate. Amelogenin was added (0.01 mg/ml, 0.1 mg/ml and 1 mg/ml) in serum-free endothelial basal growth medium. Porcine serum albumin was used as control for unspecific protein effects. The plates were incubated at 37°C and sprouting was assessed at 24 h and 48 h by microscopy and scored from 0 to 6 (arbitrary units) by a blinded observer. Integrin assay: Human dermal microvascular endothelial cells (Promocell) were seeded in complete cell growth medium alone or supplemented with 0.1 mg/ml, 1 mg/ml amelogenin or 20 µg/ml fibronectin. After 24 h incubation in 37°C, cells were gently harvested with the non-enzymatic buffer (EDTA/PBS). Upregulated integrins/subunits were detected by an Integrin-Mediated Cell Adhesion Array (Chemicon), where cells expressing specific integrins (α1, α2, α3, α4, α5, αv, β1, β2, β3, β4, β6, αvβ3, αvβ5 and α5b1) are captured by surface immobilized antibodies. Results and Discussion: Amelogenin at 0.1 mg/ml significantly (p = 0.001) increased micro-vessel outgrowth by 76 % from the explants compared with control explants after 48 h of incubation. No significant sprouting was observed with the non-specific protein control porcine serum albumin or medium only. The preliminary data from the integrin assay show that amelogenin at 0.1 mg/ml also displays a broad up-regulation of several integrins/subunits. This result is comparable to the positive control, fibronectin, an ECM protein involved in all phases of tissue repair. Taken together, the present observations suggest that the angiogenic effects might be explained by the cell binding properties of amelogenin. Conclusions: Amelogenin stimulated micro-vessel outgrowth in the chick aortic arch assay possibly through up-regulation of several integrins and subunits important for cell interaction with the ECM. The pro-angiogenic property may contribute to the beneficial effects reported after treatment of chronic ulcers with the novel ECM therapy containing amelogenin. Acknowledgements: The studies were supported by the Swedish Research Council (grant K2006-73X-09495-16-3), Mölnlycke Health Care AB, the VINNOVA VinnVäxt Program Biomedical Development in Western Sweden, and the Danish Medical Research Council (22-02-0287). References: 1. Mirastschijski U. et al. (2004) Wound Repair Regen. 12:100-108. 2. Vowden P. et al. (2006) Wound Repair Regen. 14:240-248. 3. Ågren M. S. et al. (2007) Wound Repair Regen. 15:A139.
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- Almqvist, Sofia, 1980, et al.
(författare)
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In Vitro Effect of Amelogenin on Selected Cell Mediators from Human Monocytes
- 2008
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Ingår i: 8th World Biomaterials Congress, Amsterdam, The Netherlands.
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Konferensbidrag (refereegranskat)abstract
- Introduction: Inflammation is an integral part of the normal wound healing response. Besides clearing the wound of invading microbes and debris, inflammatory cells are believed to be crucial coordinators of the repair process, acting both as phagocytes and as a major source of growth factors and other signals [1]. In non-healing skin ulcers the repair process is stuck in the inflammation phase [2]. Excessive inflammation can reflect an imbalance in the transformation of phenotype between the classically activated, inflammatory macrophage and the alternatively activated macrophage involved in immunosuppression and tissue repair [3]. Amelogenin is a hydrophobic extracellular matrix protein that under physiological conditions will self assemble into nanospheres which in turn may form larger aggregates. Treatment with amelogenin has shown enhanced skin wound healing in an in vivo study in rabbits [4]. In addition, amelogenin has been proposed to have anti-inflammatory properties by attenuation of lipopolysaccharide (LPS)- and peptidoglucan-induced production of selected pro-inflammatory cytokines by human blood cells [5]. The present study was initiated to determine the effects of amelogenin on human monocyte secretion of factors which modulate both inflammation and tissue repair. Materials and Methods: Lyophilized amelogenin from Biora AB (Malmö, Sweden) was dissolved in 17 mM acetic acid. Human monocytes were obtained from six healthy blood donors by isolation using the separation gradient PercollTM in two steps according to Pertoft et al. [6]. The isolated monocytes were cultured for 24 h at 37ºC with 5% CO2 and 95% humidity. Thereafter the supernatants and non-adherent cells were removed. Fresh medium (RPMI, 5% foetal bovine serum, antibiotics) containing amelogenin, 0, 0.01, 0.1 and 1.0 mg/ml, and with or without addition of LPS, was added to the wells in triplicates. The plates were again incubated for 24 h. The supernatants were analyzed with commercial human ELISA assays for tumour necrosis factor- (TNF-), interleukin-10 (IL-10), macrophage inflammatory protein-1 (MIP-1), monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and insulin like growth factor-1 (IGF-1). Results: Amelogenin treatment markedly altered the expression of factors by human monocytes. Amelogenin significantly reduced LPS-induced TNF- secretion, whereas the IL-10 expression was increased. Monocyte secretion of the two inflammatory chemokines MIP-1 and MCP-1 (Figure; mean ± SEM, n=6) was also affected by amelogenin treatment. Furthermore, amelogenin significantly increased monocyte secretion of VEGF (Figure; mean ± SEM, n=6) and IGF-1, although to a lesser extent, after 24 h culture. Conclusions: The amelogenin effects correlate to protein concentration, however not in a dose dependent manner, but instead the cell responses may reflect a concentration related difference in self assembly of the amelogenin protein. The observed changes in cytokine and chemokine expression are markedly affected by simultaneous LPS-induced inflammation activation, revealing possible anti-inflammatory properties of the amelogenin protein. In addition, the several-fold increase in VEGF-levels by monocytes provides a possible mechanism for the observed pro-angiogenic effect in vivo [4]. These in vitro results indicate that the extracellular matrix protein amelogenin by virtue of its interaction with human monocytes may modulate inflammation and tissue repair. Acknowledgements: The support from the Swedish Research Council (grant K2006-73X-09495-16-3), Mölnlycke Health Care Group AB and the VINNOVA VinnVäxt Program Biomedical Development in Western Sweden, is gratefully acknowledged. References: 1. Martin, P., et al. Trends Cell Biol., 15, 599, 2005. 2. Ågren, M.S., et al. Acta Derm Venereol Suppl (Stockh). 210, 3, 2000. 3. Duffield, J.S. Clin Sci (Lond), 104, 27, 2003 4. Mirastschijski, U., et al. Wound Repair Regen., 12, 100, 2004. 5. Myhre, A.E., et al. J Periodontal Res., 41, 208, 2006. 6. Pertoft, H., et al. J Immunol Methods., 33, 221, 1980.
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- Costa e Silva, Andre, et al.
(författare)
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Applications of computational thermodynamics - the extension from phase equilibrium to phase transformations and other properties
- 2007
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Ingår i: Calphad. - : Elsevier BV. - 0364-5916 .- 1873-2984. ; 31:1, s. 53-74
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Tidskriftsartikel (refereegranskat)abstract
- Complex equilibria and phase transformations involving diffusion can now be calculated quickly and efficiently. Detailed examples are given for cases which involve varying degrees of non-equilibrium and therefore time-dependence. Despite very good agreement between such calculations and experimental results, many potential end-users are still not convinced that such techniques could be usefully applied to their own specific problems. Friendly graphic interface versions of calculating software are now generally available, so the authors conclude that the most likely source of the reluctance to use such tools lies in the formulation of relevant questions and the interpretation of the results. Although the potential impact of such tools was foreseen many years ago [M. Hillert, Calculation of phase equilibria, in: Conference on Phase Transformations, 1968], few changes in the relevant teaching curricula have taken into account the availability and power of such techniques. This paper has therefore been designed not only as a collection of interesting problems, but also highlights the critical steps needed to achieve a solution. Each example includes a presentation of the "real" problem, any simplifications that are needed for its solution, the adopted thermodynamic formulation, and a critical evaluation of the results. The availability of such examples should facilitate changes in subject matter that will both make it easier for the next generation of students to use these tools, and at the same time reduce the time and effort currently needed to solve such problems by less efficient methods. The first set of detailed examples includes the deoxidation of steel by aluminum; heat balance calculations associated with ladle additions to steel; the determination of conditions that avoid undesirable inclusions; the role of methane in sintering atmospheres; interface control during the physical vapour deposition of cemented carbide; oxidation of gamma-TiAl materials; and simulation of the thermolysis of metallorganic precursors for Si-C-N ceramics and interface reaction of yttrium silicates with SiC-coated C/C-SiC composites for heat shield applications. A second set of examples, more dependent on competitive nucleation and growth, includes segregation and carburization in multicomponent steels and features a series of sophisticated simulatons using DICTRA software. Interfacial and strain energies become increasingly important in defining phase nucleation and morphology in such problems, but relatively little information is available compared to free energy and diffusion databases. The final section therefore demonstrates how computational thermodynamics, semi-empirical atomistic approaches and first-principles calculations are being used to aid filling this gap in our knowledge. (c) 2006 Elsevier Ltd. All rights reserved.
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- Enefalk, Hanna, 1976-
(författare)
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En patriotisk drömvärld : Musik, nationalism och genus under det långa 1800-talet
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The subject of this thesis is Scandinavian nationalism from the late 18th century to ca 1920. The focus lies on that particular aspect of nationalism that was at the same time the most mundane and the most enigmatic: the ever-present depicting of the nation in words, pictures and music, which in effect created a parallel universe, a patriotic dreamland. This creation was highly gendered, and the media in which it flourished most abundantly was the patriotic song. The study therefore uses song texts as its primary source material and builds upon the theoretical foundations laid by, e.g., Joan Scott and Michael Billig.Geographically, the investigation centers on Sweden, using Norway and Swedish-speaking Finland as objects of comparison. The main producers of the lyrics and their intended target groups are identified, and an in-depth analysis of a large corpus of songs is made.The main conclusion is that the patriotic songs, in spite of spreading to an ever increasing proportion of the population, were not an expression of the ‘voice of the people’ or even that of the bourgeoisie as a whole. The texts were chiefly written by male academics, and from their formative years during the Napoleonic wars the songs preserved an obsession with a warlike unmarried manhood. Only in the last decades of the period were civilian virtues and national womanhood slightly more emphasized. It is suggested that the songs, apart from being an expression of what Billig has termed ‘banal nationalism,’ also functioned as a bastion of a ‘banal androcentrism.’The thesis shows that the patriotic dreamland of the patriotic songs was designed in a way that promoted the interests of its producers and reproducers. The seemingly semi-autonomous quality of the discourse is also discussed, employing meme theory as used by, e.g., Daniel Dennett.
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- Garcia, Maria-José
(författare)
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Engineering rubber bushing stiffness formulas including dynamic amplitude dependence
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Engineering design models for the torsion and axial dynamic stiffness of carbon black filled rubber bushings in the frequency domain including amplitude dependence are presented. They are founded on a developed material model which is the result of applying a separable elastic, viscoelastic and friction rubber component model to the material level. Moreover, the rubber model is applied to equivalent strains of the strain states inside the torsion or axial deformed bushing previously obtained by the classical linear theory of elasticity, thus yielding equivalent shear moduli which are inserted into analytical formulas for the stiffness. Therefore, unlike other simplified approaches, this procedure includes the Fletcher-Gent effect inside the bushing due to non-homogeneous strain states. The models are implemented in Matlab®. In addition, an experimental verification is carried out on a commercially available bushing thus confirming the accuracy of these models which become a fast engineering tool to design the most suitable rubber bushing to fulfil user requirements. Finally, they can be easily employed in multi-body and finite element simulations
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- Hansen, Anna, 1975-
(författare)
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Ordnade hushåll : Genus och kontroll i Jämtland under 1600-talet
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study is to investigate how households acted in order to create and uphold different norms, and the effect these norms had on the construction of gender. Throughout the thesis it is argued that control was an important way to enforce certain norms, and thus make daily life work. In this context control means to have the right knowledge and to act in the right way. If you had knowledge about the norms, you could act in accordance with them, and you could also draw attention to those who did not act as they were supposed to. The main focus is on the master and the mistress of the house, who were the key figures within the household. The investigated area is Jamtland, with some examples from surrounding areas.The control executed and displayed by different people concerned formal norms, such as legislation, semi-formal norms, such as certain religious texts, and informal norms and practices in the local community. The household’s ability to control these norms is analysed in connection to three main areas: control over resources, such as property and labour, control over the household, which often meant ability to obtain knowledge of what was going on, and finally, self-control. Furthermore this investigation deals with those exposed to control, how they reacted and at times tried to evade the control carried out by others.According to the theory of Tomas Laqueur, the similarities between men and women were strongly emphasised during the 17th century. This thesis shows that the power or authority of men and women was equal in many areas, but it differed in others. The small differences in the capacity of men and women to run the household, were important in the creation of gender.
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