| 1. |
- Arvidsson, Anna, 1973, et al.
(författare)
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Early interactions between leukocytes and three different potentially bioactive titanium surface modifications
- 2011
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 97:2, s. 364-72
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to compare the early interactions between leukocytes and three different surface modifications, suggested as bioactive. Blasted titanium discs were modified by alkali and heat treatment, sodium fluoride treatment, or hydroxyapatite coating. A number of these discs were also immersed in simulated body fluid (SBF) for a week, a treatment which yielded high levels of calcium and phosphate on each surface type. The specimens were exposed for human venous blood for 32 minutes and the respiratory burst response was measured in terms of reactive oxygen species with a luminometer, and coverage of viable cells with a fluorescence microscope after staining steps. The topography, morphology, and chemistry of the surfaces were evaluated with optical interferometry and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). A high respiratory burst response was found for HA coated titanium in comparison with the other surface groups (p < 0.0005). The SBF immersion resulted in an increased respiratory burst response (p < 0.0005) and removed statistically significant differences between the surface groups. Thus, the results in the present study indicate that different titanium surface modifications influence the early inflammatory response differently, and that calcium phosphate compounds increase the inflammatory response.
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| 2. |
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| 3. |
- Arvidsson, Anna, 1973, et al.
(författare)
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Formation of calcium phosphates on titanium implants with four different bioactive surface preparations. An in vitro study
- 2007
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Ingår i: Journal of Materials Science-Materials in Medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 18:10, s. 1945-1954
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to compare the nucleating and growing behaviour on four types of bioactive surfaces by using the simulated body fluid (SBF) model. Titanium discs were blasted and then prepared by alkali and heat treatment, anodic oxidation, fluoridation, or hydroxyapatite coating. The discs were immersed in SBF for 1, 2, 4 and 6 weeks. Calcium phosphates were found on all specimens, as analysed with scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). After 1 and 2 weeks of SBF immersion more titanium was accessible with SEM/EDX on the blasted surfaces than the four bioactive surface types, indicating a difference in coverage by calcium phosphates. The Ca/P mean ratio of the surfaces was approximately 1.5 after 1 week, in contrast to the fluoridated specimens which displayed a Ca/P mean ratio of approximately 2. Powder X-ray diffraction (P-XRD) analyses showed the presence of hydroxyapatite on all types of surfaces after 4 and 6 weeks of immersion. The samples immersed for 6 weeks showed a higher degree of crystallinity than the samples immersed for 4 weeks. In conclusion, differences appeared at the early SBF immersion times of 1 and 2 weeks between controls and bioactive surface types, as well as between different bioactive surface types.
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| 4. |
- Arvidsson, Anna, 1973, et al.
(författare)
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Nucleation and growth of calcium phosphates in the presence of fibrinogen on titanium implants with four potentially bioactive surface preparations. An in vitro study.
- 2009
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Ingår i: Journal of Materials Science: Materials in Medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 20:9, s. 1869-1879
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Tidskriftsartikel (refereegranskat)abstract
- Abstract The aim of this study was to compare the nucleating and crystal growth behaviour of calcium phosphates on four types of potentially bioactive surfaces, using the simulated body fluid (SBF) model with added fibrinogen. Blasted titanium discs were modified by alkali and heat treatment, anodic oxidation, fluoride treatment, or hydroxyapatite coating. The discs were immersed in SBF with fibrinogen for periods of 3 days and 1, 2, 3 and 4 weeks. The topography, morphology, and chemistry of the surfaces were evaluated with optical interferometry, scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX), and x-ray photoelectron spectroscopy (XPS), respectively. All surface modifications showed early calcium phosphate formation after 3 days, and were almost completely covered by calcium phosphates after 2 weeks. After 4 weeks, the Ca/P ratio was approximately 2.0 for all surface groups except the fluoride modified surface, which had a Ca/P ratio of 1.0–1.5. XPS measurements of the nitrogen concentration, which can be interpreted as an indirect measure of the protein content, reached a peak value after 3 days immersion and decreased thereafter. In conclusion, the results in the present study, when compared to earlier SBF studies without proteins, showed that fibrinogen stimulates calcium phosphates formation. Furthermore, no pronounced differences could be detected between blasted controls and the potentially bioactive specimens.
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| 5. |
- Barkarmo, Sargon, et al.
(författare)
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Enhanced bone healing around nanohydroxyapatite-coated polyetheretherketone implants : An experimental study in rabbit bone
- 2014
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Ingår i: Journal of biomaterials applications. - : Sage Publications. - 0885-3282 .- 1530-8022. ; 29:5, s. 737-747
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate the bone response to threaded polyetheretherketone (PEEK) implants coated with nanohydroxyapatite. Materials and methods: A total of 39 PEEK implants were coated with nanocrystalline hydroxyapatite and 39 uncoated implants were used as controls. The implant surface was characterized by optical interferometry and scanning electron microscope. The implants were inserted in the tibia and femur of 13 rabbits. After 6 weeks of healing, quantitative and qualitative analyses were performed. Results: The test implants showed significantly higher removal torque test values compared with the control group. Histomorphometric evaluation demonstrated higher bone-to-implant contact for the test implants; however, there were no differences in bone area between the groups. Qualitative histological analyses demonstrated inflammatory cellular reactions in close vicinity of both implant surfaces. A two-cell layer of foreign body giant cells was observed irrespective of sample type. Conclusion: Our findings demonstrate that implants with a threaded design render good stability to PEEK in both coated and uncoated implants. Nanohydroxyapatite-coated PEEK implants demonstrated improved bone formation compared with uncoated controls.
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| 6. |
- Franke Stenport, Victoria, 1970, et al.
(författare)
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Precipitation of calcium phosphate in the presence of albumin on titanium implants with four different possibly bioactive surface preparations. An in vitro study
- 2008
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Ingår i: Journal of Materials Science: Materials in Medicine. - : Springer Science and Business Media LLC. - 0957-4530 .- 1573-4838. ; 19:12, s. 3497-3505
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to compare the nucleating behaviour on four types of bioactive surfaces by using the simulated body fluid (SBF) model with the presence albumin. Titanium discs were blasted (B) and then prepared by alkali and heat treatment (AH), anodic oxidation (AO), fluoridation (F), or hydroxyapatite coating (HA). The discs were immersed in SBF with 4.5 mg/ml albumin for 3 days, 1, 2, 3 and 4 weeks and analysed with scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX) and X-ray photoelectron spectroscopy (XPS). Topographic surface characterisation was performed with a contact stylus profilometer. The results demonstrated that the bioactive surfaces initiated an enhanced calcium phosphate (CaP) formation and a more rapid increase of protein content was present on the bioactive surfaces compared to the blasted control surface. The observation was present on all bioactive surfaces. The fact that there was a difference between the bioactive surfaces and the blasted control surface with respect to precipitation of CaP and protein content on the surfaces support the fact that there may be biochemical advantages in vivo by using a bioactive surface.
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| 7. |
- Gustafsson, Sanna Aila, 1972-
(författare)
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The importance of being thin : perceived expectations from self and others and the effect on self-evaluation in girls with disordered eating
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aims of this thesis were to examine personal standards, self-evaluation and attitudes to eating and weight in the development of disturbed eating in adolescent girls, and to examine how adolescent girls with a clinical eating disorder reflect upon and deal with perceived expectations in daily life.Studies I and II were quantitative studies, conducted in a population-based longitudinal study. Studies III and IV were qualitative interview studies of girls who were suffering from eating disorders and the data were analysed using a phenomenographic approach.Study I showed that high personal standards expressed in a competitive way were specific for the girls with disturbed eating. These girls also reported a negative physical self-evaluation and often believed that thinness would make them more popular. In study II variables concerning attitudes to eating and weight and physical self-evaluation emerged as risk factors for disturbed eating, whereas personal standards or self-evaluation in general did not. Protective factors were a low BMI, healthy eating attitudes, an accepting attitude towards body size and a positive self-evaluation. Three categories of perceived expectations were described in study III: expectations from others, self-imposed expectations and conflicting expectations. Many informants had problems identifying expectations that were not explicit and they interpreted them as self-imposed. In study IV the various ways in which the informants reflected on dealing with these expectations were summarized into three qualitatively different conceptions: being oneself, adapting to different situations and presenting oneself in a positive light. These conceptions were expressed in five patterns of action, which could have various functions for different individuals and in different situations.The results suggest that in order to prevent and treat eating disorders and related problems it is essential to integrate both intrapersonal and contextual factors that contribute to the development and maintenance of these conditions.
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| 8. |
- Göransson, Anna, 1970, et al.
(författare)
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An in vitro comparison of possibly bioactive titanium implant surfaces.
- 2009
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 88:4, s. 1037-1047
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to compare Ca and P formation (CaP) and subsequent bone cell response of a blasted and four different possibly bioactive commercially pure (cp) titanium surfaces; 1. Fluoride etched (Fluoride), 2. Alkali-heat treated (AH), 3. Magnesium ion incorporated anodized (TiMgO), and 4. Nano HA coated and heat treated (nano HA) in vitro. Furthermore, to evaluate the significance of the SBF formed CaP coat on bone cell response. The surfaces were characterized by Optical Interferometry, Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). CaP formation was evaluated after 12, 24 and 72 h in simulated body fluid (SBF). Primary human mandibular osteoblast-like cells were cultured on the various surfaces subjected to SBF for 72 h. Cellular attachment, differentiation (osteocalcin) and protein production (TGF-beta(1)) was evaluated after 3 h and 10 days respectively. Despite different morphological appearances, the roughness of the differently modified surfaces was similar. The possibly bioactive surfaces gave rise to an earlier CaP formation than the blasted surface, however, after 72 h the blasted surface demonstrated increased CaP formation compared to the possibly bioactive surfaces. Subsequent bone cell attachment was correlated to neither surface roughness nor the amount of formed CaP after SBF treatment. In contrast, osteocalcin and TGF-beta(1) production were largely correlated to the amount of CaP formed on the surfaces. However, bone response (cell attachment, osteocalcin and TGF-F production) on the blasted controls were similar or increased compared to the SBF treated fluoridated, AH and TiMgO surface. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008.
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| 9. |
- He, Wenxiao, 1985, et al.
(författare)
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Formation of Bone-like Nanocrystalline Apatite Using Self-Assembled Liquid Crystals
- 2012
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 24:5, s. 892-902
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Tidskriftsartikel (refereegranskat)abstract
- A two-step process using liquid crystalline phases combined with controlled postcrystallization for the preparation of bone-like apatite has been developed. First, amorphous calcium phosphate (ACP) spherules with a diameter of 10.8 +/- 1.4 nm and specific surface area (SSA) in the range of 150-170 m(2)/g were synthesized within a reverse hexagonal liquid crystalline (LC) phase. Second, the ACP spherules were dispersed and aged in Milli-Qwater, where they crystallized into poorly crystalline apatite (PCA). The addition of heparin during aging was explored, which was shown to retard the ACP - PCA conversion. The particle formation within the LC phase was monitored using synchrotron small-angle X-ray scattering, and the formed materials were characterized by X-ray diffraction, conventional and high-resolution transmission electron microscopy, nitrogen adsorption, thermogravimetry with infrared-coupled analysis, and Raman spectroscopy. The PCA formed using the LC aging route presented bone-resembling features, such as,Ca2+ and OH- deficiency, CO32- substitution, poor crystallinity; and ultrahigh SSA of 356 m(2)/g. The resulting particles were compared to hydroxyapatite synthesized via a conventional water-based precipitation method. The LC-aging route exhibited excellent controllability over the CaP crystallization, which enabled facile tailoring of the resulting material properties for different types of application.
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| 10. |
- Kjellin, Per, 1972
(författare)
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Effects of polymeric surfactants on the crystallisation of inorganic materials
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns effects of polymeric surfactants on the crystal growth of inorganic structures. The crystal growth of calcium carbonate on steel surfaces was studied with a heat exchanger cell and with an electrochemical method. Two copolymeric surfactants, differing in hydrophobic / hydrophilic ratio, were synthesised and their effect on the crystallisation was investigated. It was found that the more hydrophobic of the polymers prevented CaCO3 crystallisation most efficiently. The same results were obtained with the electrochemical method. Lignin, a biopolymer occurring naturally in wood, was evaluated in the heat exchanger cell and its efficiency as an antiscalant was assessed. Lignin had a similar antiscaling efficiency as poly(acrylic acid), but it had only a minor effect on which polymorph that formed. In the second part of this thesis, synthesis of CaCO3, SrCO3, Ag and CdS with the use of liquid crystalline phases as templates, is described. Synthesis of CaCO3 was made in a hexagonal and reverse hexagonal phase. With both phases it was possible to obtain CaCO3 crystals of very small dimensions and corresponding high specific surface areas, 8 nm in diameter and 226 m2/g, respectively. A similar method was used to synthesise SrCO3. It was discovered that a high specific surface area of SrCO3 (232 m2/g) was only achievable with a reversed hexagonal phase as template. The normal hexagonal phase yielded surface areas of around 36 m2/g. Synthesis of metallic silver in a reverse hexagonal phase was studied, using a slightly different method to induce crystallisation. It was found that the surfactants acted as reducing agent, forming metallic silver from an aqueous silver nitrate solution.
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