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  • 1.
    Addi, Simon
    et al.
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Hedayati-Khams, Arjang
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Poya, Amin
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Sjögren, Göran
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Interface gap size of manually and CAD/CAM-manufactured ceramic inlays/onlays in vitro.2002In: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 30, no 1, p. 53-58Article in journal (Refereed)
    Abstract [en]

    Objectives : To determine the fit of ceramic inlays manufactured using a recently introduced CAD/CAM-system (Decim) and of two types of laboratory-made heat-pressed ceramics (IPS Empress and Opc).

    Materials and methods : Extracted human premolars were prepared to receive mesio-occlusodistal (MOD) ceramic inlays, for which 10 Denzir, 10 IPS Empress, and 10 Opc were fabricated. The Denzir restorations were produced by the manufacturer of the CAD/CAM-system, and the IPS Empress and Opc by student dental technicians. Before luting the internal fit on the diestone models and on the premolars was determined using replicas. After luting on the premolars with a resin composite the marginal and internal fit were measured. The values were analyzed statistically using ANOVA and Scheffe's test at a significance level of p<0.05.

    Results : Before luting there were no significant differences ( p>0.05) in the internal gap width between the three systems studied when placed on their matching diestone models. When placed on the premolars a significant difference ( p<0.01) in the internal fit was seen between Empress and Opc before luting, whereas there were no significant differences ( p>0.05) between Empress and Denzir and between Opc and Denzir. Between the diestone models and the premolars there were significant differences ( p<0.01) in the internal fit, except for IPS Empress. After luting there were no significant differences ( p>0.05) between IPS Empress and Denzir, whereas the marginal gap width was significantly wider ( p<0.001) for Opc than for IPS Empress and Denzir. The internal fit was significantly ( p<0.001) wider for Opc than for IPS Empress, whereas there were no significant differences ( p>0.05) between IPS Empress and Denzir or between Opc and Denzir.

    Conclusion : After luting there were only slight differences in the fit between the restorations fabricated using the three different manufacturing techniques and ceramics. Therefore, long-term follow-up studies are needed to assess the clinical significance of the slight differences between the three systems.

  • 2. Blau, Axel
    et al.
    Murr, Angelika
    Wolff, Sandra
    Sernagor, Evelyne
    Medini, Paolo
    Iurilli, Giuliano
    Ziegler, Christiane
    Benfenati, Fabio
    Flexible, all-polymer microelectrode arrays for the capture of cardiac and neuronal signals2011In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 32, no 7, p. 1778-1786Article in journal (Refereed)
    Abstract [en]

    Microelectrode electrophysiology has become a widespread technique for the extracellular recording of bioelectrical signals. To date, electrodes are made of metals or inorganic semiconductors, or hybrids thereof. We demonstrate that these traditional conductors can be completely substituted by highly flexible electroconductive polymers. Pursuing a two-level replica-forming strategy, conductive areas for electrodes, leads and contact pads are defined as microchannels in poly(dimethylsiloxane) (PDMS) as a plastic carrier and track insulation material. These channels are coated by films of organic conductors such as polystyrenesulfonate-doped poly(3,4-ethylenedioxy-thiophene) (PEDOT:PSS) or filled with a graphite-PDMS (gPDMS) composite, either alone or in combination. The bendable, somewhat stretchable, non-cytotoxic and biostable all-polymer microelectrode arrays (polyMEAs) with a thickness below 500 μm and up to 60 electrodes reliably capture action potentials (APs) and local field potentials (LFPs) from acute preparations of heart muscle cells and retinal whole mounts, in vivo epicortical and epidural recordings as well as during long-term in vitro recordings from cortico-hippocampal co-cultures.

  • 3. Ekstrand-Hammarström, Barbro
    et al.
    Hong, Jaan
    Davoodpour, Padideh
    Sandholm, Kerstin
    Ekdahl, Kristina N.
    Bucht, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Nilsson, Bo
    TiO2 nanoparticles tested in a novel screening whole human blood model of toxicity trigger adverse activation of the kallikrein system at low concentrations2015In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 51, p. 58-68Article in journal (Refereed)
    Abstract [en]

    There is a compelling need to understand and assess the toxicity of industrially produced nanoparticles (NPs). In order to appreciate the long-term effects of NPs, sensitive human-based screening tests that comprehensively map the NP properties are needed to detect possible toxic mechanisms. Animal models can only be used in a limited number of test applications and are subject to ethical concerns, and the interpretation of experiments in animals is also distorted by the species differences. Here, we present a novel easy-to-perform highly sensitive whole-blood model using fresh non-anticoagulated human blood, which most justly reflects complex biological cross talks in a human system. As a demonstrator of the tests versatility, we evaluated the toxicity of TiO2 NPs that are widely used in various applications and otherwise considered to have relatively low toxic properties. We show that TiO2 NPs at very low concentrations (50 ng/mL) induce strong activation of the contact system, which in this model elicits thromboinflammation. These data are in line with the finding of components of the contact system in the protein corona of the TiO2 NPs after exposure to blood. The contact system activation may lead to both thrombotic reactions and generation of bradykinin, thereby representing fuel for chronic inflammation in vivo and potentially long-term risk of autoimmunity, arteriosclerosis and cancer. These results support the notion that this novel whole-blood model represents an important contribution to testing of NP toxicity. 

  • 4. Georgiou, Melanie
    et al.
    Golding, Jon P.
    Loughlin, Alison J.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Phillips, James B.
    Engineered neural tissue with aligned, differentiated adipose-derived stem cells promotes peripheral nerve regeneration across a critical sized defect in rat sciatic nerve2015In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 37, p. 242-251Article in journal (Refereed)
    Abstract [en]

    Adipose-derived stem cells were isolated from rats and differentiated to a Schwann cell-like phenotype in vitro. The differentiated cells (dADSCs) underwent self-alignment in a tethered type-1 collagen gel, followed by stabilisation to generate engineered neural tissue (EngNT-dADSC). The pro-regenerative phenotype of dADSCs was enhanced by this process, and the columns of aligned dADSCs in the aligned collagen matrix supported and guided neurite extension in vitro. EngNT-dADSC sheets were rolled to form peripheral nerve repair constructs that were implanted within NeuraWrap conduits to bridge a 15 mm gap in rat sciatic nerve. After 8 weeks regeneration was assessed using immunofluorescence imaging and transmission electron microscopy and compared to empty conduit and nerve graft controls. The proportion of axons detected in the distal stump was 3.5 fold greater in constructs containing EngNT-dADSC than empty tube controls. Our novel combination of technologies that can organise autologous therapeutic cells-within an artificial tissue construct provides a promising new cellular biomaterial for peripheral nerve repair. 

  • 5.
    Huttu, Mari
    et al.
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Turunen, Siru
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Sokolinski, Viktoria
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Tiitu, Virpi
    Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland; SIB-Labs, University of Eastern Finland, Kuopio, Finland.
    Lammi, Mikko
    Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland; Biocenter Kuopio, University of Eastern Finland, Kuopio, Finland.
    Korhonen, Rami K
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Effects of medium and temperature on cellular responses in the superficial zone of hypo-osmotically challenged articular cartilage.2012In: Journal of Functional Biomaterials, ISSN 2079-4983, Vol. 3, no 3, p. 544-555, article id 23807905Article in journal (Refereed)
    Abstract [en]

    Osmotic loading of articular cartilage has been used to study cell-tissue interactions and mechanisms in chondrocyte volume regulation in situ. Since cell volume changes are likely to affect cell's mechanotransduction, it is important to understand how environmental factors, such as composition of the immersion medium and temperature affect cell volume changes in situ in osmotically challenged articular cartilage. In this study, chondrocytes were imaged in situ with a confocal laser scanning microscope (CLSM) through cartilage surface before and 3 min and 120 min after a hypo-osmotic challenge. Samples were measured either in phosphate buffered saline (PBS, without glucose and Ca(2+)) or in Dulbecco's modified Eagle's medium (DMEM, with glucose and Ca(2+)), and at 21 °C or at 37 °C. In all groups, cell volumes increased shortly after the hypotonic challenge and then recovered back to the original volumes. At both observation time points, cell volume changes as a result of the osmotic challenge were similar in PBS and DMEM in both temperatures. Our results indicate that the initial chondrocyte swelling and volume recovery as a result of the hypo-osmotic challenge of cartilage are not dependent on commonly used immersion media or temperature.

  • 6.
    Håff, Anna
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    Löf, Hanna
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    Gunne, Johan
    Umeå University, Faculty of Medicine, Department of Odontology, Prosthetic Dentistry.
    Sjögren, Göran
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    A retrospective evaluation of zirconia-fixed partial dentures in general practices: an up to 13-year study2015In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 31, no 2, p. 162-170Article in journal (Refereed)
    Abstract [en]

    Objectives: To evaluate zirconia-based fixed partial dentures (FPDs) after more than 8 years in clinical service.

    Methods: Patients treated between 2000 and 2004 with zirconia FPDs were identified from the records of a manufacturer of FPD substructures. Of the 45 patients who met the inclusion criteria 30 attended the appointment and 33 FPDs were evaluated using modified California Dental Association (CDA) criteria. In addition, plaque and the bleeding index were registered. Patient satisfaction with the restorations was evaluated using a 10-point visual analog scale (VAS).

    Results: All the FPDs were made using CAD/CAM and hot isostatic pressed yttria-tetragonal zirconia polycrystal (HIPed Y-TZP) ceramic (Denzir) and were placed within general practices. The mean observation period was 9.6 ± 1.6 years (range 3.0–13.1 years). The CDA rating was 90% satisfactory for the surface. Corresponding figures for anatomic form, color and margin integrity were 94%, 100% and 94%, respectively. Regarding surface three (9.7%) FPDs exhibited veneer chipping and were rated ‘not acceptable’. For margin integrity two (6.5%) were rated ‘not acceptable’ because of caries. For anatomic form two (6.1%) were rated ‘not acceptable’ due to two lost FPDs. No significant differences were seen between the FPDs and controls for plaque and bleeding. The Kaplan–Meier survival rate (still in clinical function) was 94%, the success rate (technical events accounted for) 91% and (biological events accounted for) 73%. Based on the VAS the mean value for patient satisfaction was 9.3 ± 1.2.

    Significance: Ninety-four percent of the FPDs were still in clinical function. HIPed Y-TZP could serve as an alternative for FPD treatments similar to those in the current study.

  • 7. Johansson, Kristin
    et al.
    Christophliemk, Hanna
    Johansson, Caisa
    Jönsson, Leif
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Järnström, Lars
    The effects of coating structure and water-holding capacity on the oxygen-scavenging ability of enzymes embedded in the coating layer2013In: TAPPI Journal, ISSN 0734-1415, Vol. 12, no 6, p. 43-52Article in journal (Refereed)
    Abstract [en]

    Enzymes catalyzing oxygen scavenging were embedded in latex-based coatings with and without barrier kaolin clay to produce material for active packages. The clay was used to create a porous structure, and the closed-structure matrix consisted of a biopolymer comprising either starch or gelatin to increase the water uptake of the coating. The effects of the porous open structure and of the water uptake of the coated layer on the oxygen-scavenging ability of the embedded enzymes were examined at both 75% and 100% relative humidity. The results showed that the porous clay structure led to higher oxygen-scavenging capacity than that of a closed structure at both test conditions by enabling a high diffusion rate for oxygen and glucose to the active sites of the enzymes. The addition of a water-holding biopolymer did not always significantly affect the oxygen-scavenging capacity. However for a less-porous layer at 100% relative humidity, an increase in the amount of biopolymer resulted in an increase in oxygen-scavenging capacity. The results were treated statistically using multiple-factor analysis where the most important factor for the oxygen-scavenging ability was found to be the addition of clay. The coatings were also characterized with respect to water vapor uptake, overall migration, porosity, and scanning electron microscopy images.

  • 8.
    Kou, Wen
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    On dental ceramics and their fracture: a laboratory and numerical study2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Background Surface treatments and irregularities in the surfaces may affect the fracture of ceramics. The effects of various treatments on the surface texture of different types of ceramic cores/substructures was therefore qualitatively, quantitatively and numerically evaluated. Since fractures in ceramics are not fully understood, the fracture behavior in dental ceramic core/substructures was also studied using both established laboratory methods and newly developed numerical methods.

    Methods The surfaces of dental ceramic cores/substructures were studied qualitatively by means of a fluorescence penetrant method and scanning electron microscopy, quantitatively evaluated using a profilometer and also numerical simulation. In order to study fracture in zirconia-based fixed partial denture (FPD) frameworks, fractographic analysis in combination with fracture tests and newly developed two-dimensional (2D) and three-dimensional (3D) numerical modeling methods were used. In the numerical modeling methods, the heterogeneity within the materials was described by means of the Weibull distribution law. The Mohr–Coulomb failure criterion with tensile strength cut-off was used to judge whether the material was in an elastic or failed state.

    Results Manual grinding/polishing could smooth the surfaces on some of the types of dental ceramic cores/substructures studied. Using the fluorescence penetrant method, no cracks/flaws apart from milling grooves could be seen on the surfaces of machined zirconia-based frameworks. Numerical simulations demonstrated that surface grooves affect the fracture of the ceramic bars and the deeper the groove, the sooner the bar fractured. In the laboratory tests the fracture mechanism in the FPD frameworks was identified as tensile failure and irregularities on the ceramic surfaces could act as fracture initiation sites. The numerical modeling codes allowed a better understanding of the fracture mechanism than the laboratory tests; the stress distribution and the fracture process could be reproduced using the mathematical methods of mechanics. Furthermore, a strong correlation was found between the numerical and the laboratory results.

    Conclusion Based on the findings in the current thesis, smooth surfaces in areas of concentrated tensile stress would be preferable regarding the survival of ceramic restorations, however, the surfaces of only some of the ceramic cores/substructures could be significantly affected by manual polishing. The newly developed 3D method clearly showed the stress distribution and the fracture process in ceramic FPD frameworks, step by step, and seems to be an appropriate tool for use in the prediction of the fracture process in ceramic FPD frameworks.

  • 9.
    Kou, Wen
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science. Umeå University, Faculty of Medicine, Department of Odontology.
    Kou, Shaoquan
    Department of Civil and Mining Engineering, Luleå University of Technology, Luleå, Sweden.
    Liu, Hongyuan
    Department of Civil and Mining Engineering, Luleå University of Technology, Luleå, Sweden.
    Sjögren, Göran
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    Numerical modeling of the fracture process in a three-unit all-ceramic fixed partial denture2007In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 23, no 8, p. 1042-1049Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: The main objectives were to examine the fracture mechanism and process of a ceramic fixed partial denture (FPD) framework under simulated mechanical loading using a recently developed numerical modeling code, the R-T(2D) code, and also to evaluate the suitability of R-T(2D) code as a tool for this purpose. METHODS: Using the recently developed R-T(2D) code the fracture mechanism and process of a 3U yttria-tetragonal zirconia polycrystal ceramic (Y-TZP) FPD framework was simulated under static loading. In addition, the fracture pattern obtained using the numerical simulation was compared with the fracture pattern obtained in a previous laboratory test. RESULTS: The result revealed that the framework fracture pattern obtained using the numerical simulation agreed with that observed in a previous laboratory test. Quasi-photoelastic stress fringe pattern and acoustic emission showed that the fracture mechanism was tensile failure and that the crack started at the lower boundary of the framework. The fracture process could be followed both in step-by-step and step-in-step. SIGNIFICANCE: Based on the findings in the current study, the R-T(2D) code seems suitable for use as a complement to other tests and clinical observations in studying stress distribution, fracture mechanism and fracture processes in ceramic FPD frameworks.

  • 10.
    Kou, Wen
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Qiao, Jiyan
    Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.
    Chen, Li
    Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.
    Ding, Yansheng
    Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.
    Sjögren, Göran
    Umeå University, Faculty of Medicine, Department of Odontology.
    Numerical simulation of the fracture process in ceramic FPD frameworks caused by oblique loading2015In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 50, p. 206-214Article in journal (Refereed)
    Abstract [en]

    Using a newly developed three-dimensional (3D) numerical modeling code, an analysis was performed of the fracture behavior in a three-unit ceramic-based fixed partial denture (FPD) framework subjected to oblique loading. All the materials in the study were treated heterogeneously; Weibull׳s distribution law was applied to the description of the heterogeneity. The Mohr-Coulomb failure criterion with tensile strength cut-off was utilized in judging whether the material was in an elastic or failed state. The simulated loading area was placed either on the buccal or the lingual cusp of a premolar-shaped pontic with the loading direction at 30°, 45°, 60°, 75° or 90° angles to the occlusal surface. The stress distribution, fracture initiation and propagation in the framework during the loading and fracture process were analyzed. This numerical simulation allowed the cause of the framework fracture to be identified as tensile stress failure. The decisive fracture was initiated in the gingival embrasure of the pontic, regardless of whether the buccal or lingual cusp of the pontic was loaded. The stress distribution and fracture propagation process of the framework could be followed step by step from beginning to end. The bearing capacity and the rigidity of the framework vary with the loading position and direction. The framework loaded with 90° towards the occlusal surface has the highest bearing capacity and the greatest rigidity. The framework loaded with 30° towards the occlusal surface has the least rigidity indicating that oblique loading has a major impact on the fracture of ceramic frameworks.

  • 11.
    Lappalainen, Reijo
    et al.
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Korhonen, Hannu
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Kaitainen, Salla
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Myllymaa, Sami
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Qu, Chengjuan
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.
    Lammi, Mikko J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Nanostructured coatings for biomedical applications by ultra short pulsed laser deposition2015In: Comprehensive guide for nanocoatings technology: Volume 3, Properties and development / [ed] Mahmoud Aliofkhadzraei, Nova Science Publishers, Inc., 2015, 3, p. 309-323Chapter in book (Refereed)
    Abstract [en]

    Ultra short pulsed laser deposition (USPLD) technique is a novel, well-controlled physical vapour deposition method to deposit a wide variety of nanocoatings on solid substrate materials with good adhesion and various surface nanotopographies. Coating materials include ceramics, like Al2O3, TiO2, carbon nitride and amorphous diamond, metals, such as platinum, titanium and Ti6Al4V, as well as polymers, composite materials and so on. In this chapter, we demonstrate and review the possibilities of USPLD for modified biomaterial surfaces in medical applications, such as cell culture plates, electrodes or implants used in orthopaedics and dentistry. The coatings are used to control, e.g., cell growth and proliferation, bacterial adhesion, bioelectrical properties, corrosion, friction and wear.

  • 12.
    Lindholm-Sethson, Britta
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ardlin, Berit
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    Effects of pH and fluoride concentration on the corrosion of titanium2008In: Journal of Biomedical Materials Research Part A, ISSN 1549-3296, Vol. 86A, no 1, p. 149-159Article in journal (Refereed)
    Abstract [en]

    The aim of this investigation was to confirm and summarize the corrosion behavior of titanium in saline solution at different pH and fluoride concentration, and to characterize the surface films and the stability of a passive and aged titanium surface using open circuit potential measurements, electrochemical impedance spectroscopy, and anodic polarization curves. The results from the electrochemical measurements were related to titanium released after 2-min brushing with saline solutions with different pH and fluoride concentration, that is, simulating tooth brushing with fluoride containing prophylactic substances. Titanium was analyzed using atomic adsorption spectrophotometry. The pH in the saline solution was varied between 4 and 7 with additions of sodium fluoride up to 1.0 wt %. The presence of fluoride in solution was unfavorable for the stability of titanium and led to corrosion and the release of titanium especially at low pH. The combination of low pH and presence of fluoride ions in solution destroyed a passive film on the titanium surface even after aging for 170 h in neutral saline solution. The results do not necessarily imply the occurrence of biological soft tissue related effects even if a physical contact between titanium and the surrounding milieu is prevalent. To provide a general understanding of electrochemical techniques in biomaterial research, much effort was put in the qualitative description of the results, with the intention to provide a broader understanding of especially the impedance method to other researchers. (c) 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007.

  • 13.
    Melo Filho, Alberto
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Drotz, Stina
    Tsai, Chia-Jung
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Ragnvaldsson, Daniel
    Larsson, Christer
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Heat-killing of Legionella in biological sludge from a paper and pulp mill water treatment plant2015In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, no 1, p. 121-125Article in journal (Refereed)
    Abstract [en]

    Paper and pulp mills use biological water treatment plants to reduce Chemical Oxygen Demand (COD) release to the environment. In the end of the process, microorganisms are concentrated into a biological sludge. Among the microbes thriving in these plants are Legionella, causing the Legionnaires disease. Combustion of the biological sludge produced at a plant results in unwanted downstream effects on the production and probably increased formation of nitrogen oxides (NOx) in the recovery boiler. Due to the disadvantages of combustion, the possibility to sterilize biological sludge has been investigated as a part of the continuously ongoing work at Metsa to improve occupational safety and reduce impact on the environment in a proactive way. A method to eradicate Legionellae in biological sludge would improve safety and ecological sustainability if the sludge instead is safely composted and used as e.g. soil fertilizer. Here we have assessed the time to death upon sludge heat treatment of a pathogenic L. pneumophila serogroup 1 strain, a L. longbeachae strain and the bacteria naturally occurring in biological sludge at the Metsa Board, Husum mill, Sweden. Time to death decreased with increasing temperatures up to 65 degrees C, where higher temperatures resulted in neglectable gain in time to death.

  • 14. Mladenović, Živko
    et al.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Willman, Britta
    Umeå University, Faculty of Medicine, Department of Odontology.
    Shahabi, Kaveh
    Umeå University, Faculty of Medicine, Department of Odontology.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ransjö, Maria
    Soluble silica inhibits osteoclast formation and bone resorption in vitro2014In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 10, no 1, p. 406-418Article in journal (Refereed)
    Abstract [en]

    Several studies have suggested that silicon (Si) may be essential for normal development of connective tissue and the skeleton. Positive effects of Si from the diet as well as from Si-containing biomaterials, such as Bioactive glass 45S5 (BG), have been demonstrated. Studies have reported that Si stimulates osteoblast proliferation and differentiation. However, effects of Si on osteoclasts have not been directly addressed earlier. The purpose of the present in vitro study was to clarify if Si has regulatory effects on osteoclasts formation and bone resorption. Effects of BG, BG dissolution extracts and Si containing cell culture medium were investigated in a mouse calvarial bone resorption assay and osteoclast formation assays (mouse bone marrow cultures and RAW264.7 cell cultures). We conclude from our results that Si causes significant inhibition of osteoclast phenotypic gene expressions, osteoclast formation and bone resorption in vitro. In conclusion, the present study suggests that Si has a dual nature in bone metabolism with stimulatory effects on osteoblasts and inhibitory effects on osteoclasts. This suggested property of Si might be interesting to further explore in future biomaterials for treatments of bone defects in patients.

  • 15.
    Mohl, Melinda
    et al.
    Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering, University of Oulu, Finland.
    Aron Dombovari, Aron
    Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering, University of Oulu, Finland.
    Tuchina, Elena S.
    Department of Biology, Saratov State University, Saratov, Russia .
    Petrov, Pavel O.
    Department of Biology, Saratov State University, Saratov, Russia .
    Bibikova, Olga A.
    Optoelectronics and Measurement Techniques Laboratory, Department of Electrical Engineering, University of Oulu, Finland ; Department of Nonlinear Processes, Saratov State University, Russia.
    Skovorodkin, Ilya
    Biocenter Oulu, University of Oulu, Finland.
    Popov, Alexey P.
    Optoelectronics and Measurement Techniques Laboratory, Department of Electrical Engineering, University of Oulu, Finland.
    Rautio, Anne-Riikka
    Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering, University of Oulu, Finland.
    Sarkar, Anjana
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Finland.
    Huuhtanen, Mika
    Mass and Heat Transfer Process Laboratory, Department of Process and Environmental Engineering, University of Oulu, Finland.
    Vainio, Seppo
    Biocenter Oulu, University of Oulu, Finland.
    Keiski, Riitta L.
    Mass and Heat Transfer Process Laboratory, Department of Process and Environmental Engineering, University of Oulu, Finland.
    Prilepsky, Arthur
    Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences, Saratov, Russia .
    Kukovecz, Akos
    Department of Applied and Environmental Chemistry, University of Szeged, Hungary ; MTA-SZTE Lendület Porous Nanocomposites Research Group, Szeged, Hungary.
    Konya, Zoltan
    Department of Applied and Environmental Chemistry, University of Szeged, Hungary ; MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Szeged, Hungary.
    Tuchincmn, Valery V.
    Optoelectronics and Measurement Techniques Laboratory, Department of Electrical Engineering, University of Oulu, Finland ; Research-Educational Institute of Optics and Biophotonics, Saratov State University, Russia ; nstitute of Precise Mechanics and Control of Russian Academy of Sciences, Saratov, Russia.
    Kordas, Krisztian
    Microelectronics and Materials Physics Laboratories, Department of Electrical Engineering, University of Oulu, Finland.
    Titania nanofibers in gypsum composites: an antibacterial and cytotoxicology study2014In: Journal of Material Chemistry B, ISSN 2050-750X, Vol. 2, no 10, p. 1307-1316Article in journal (Refereed)
    Abstract [en]

    Further developments of antibacterial coatings based on photocatalytic nanomaterials could be a promising route towards potential environmentally friendly applications in households, public buildings and health care facilities. Hereby we describe a simple chemical approach to synthesize photocatalytic nanomaterial-embedded coatings using gypsum as a binder. Various types of TiO2 nanofiber-based photocatalytic materials (nitrogen-doped and/or palladium nanoparticle decorated) and their composites with gypsum were characterized by means of scanning (SEM) and transmission (TEM) electron microscopy as well as electron and X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) techniques. These gypsum-based composites can be directly applied as commercially available paints on indoor walls. Herein we report that surfaces coated with photocatalytic composites exhibit excellent antimicrobial properties by killing both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) under blue light. In the case of MSSA cells, the palladium nanoparticle-decorated and nitrogen-doped TiO2 composites demonstrated the highest antimicrobial activity. For the MRSA strain even pure gypsum samples were proven to be efficient in eradicating Gram-positive human pathogens. The cytotoxicity of freestanding TiO2 nanofibers was revealed by analyzing the viability of HeLa cells using MTT and fluorescent cell assays.

  • 16.
    Myllymaa, Katja
    et al.
    Microsensor Laboratory, School of Engineering and Technology, Savonia University of Applied Sciences, Kuopio, Finland; Department of Physics, University of Kuopio, Kuopio, Finland.
    Myllymaa, Sami
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Korhonen, Hannu
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Lammi, Mikko
    Departmentof Applied Biotechnology, University of Kuopio, Kuopio; Biocenter Kuopio, University of Kuopio, Kuopio, Finland.
    Saarenpää, Hanna
    Department of Chemistry, University of Joensuu, Joensuu, Finland.
    Suvanto, Mika
    Department of Chemistry, University of Joensuu, Joensuu, Finland.
    Pakkanen, Tapani
    Department of Chemistry, University of Joensuu, Joensuu, Finland.
    Tiitu, Virpi
    Department of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland.
    Lappalainen, Reijo
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Improved adherence and spreading of Saos-2 cells on polypropylene surfaces achieved by surface texturing and carbon nitride coating.2009In: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 20, no 11, p. 2337-2347, article id 19507005Article in journal (Refereed)
    Abstract [en]

    The adhesion and contact guidance of human primary osteogenic sarcoma cells (Saos-2) were characterized on smooth, microstructured (MST) and micro- and nano-structured (MNST) polypropylene (PP) and on the same samples with a silicon-doped carbon nitride (C(3)N(4)-Si) coating. Injection molding was used to pattern the PP surfaces and the coating was obtained by using ultra-short pulsed laser deposition (USPLD). Surfaces were characterized using atomic force microscopy and surface energy components were calculated according to the Owens-Wendt model. The results showed C(3)N(4)-Si coated surfaces to be significantly more hydrophilic than uncoated ones. In addition, there were 86% more cells in the smooth C(3)N(4)-Si coated PP compared to smooth uncoated PP and 551%/476% more cells with MST/MNST C(3)N(4)-Si coated PP than could be obtained with MST/MNST uncoated PP. Thus the adhesion, spreading and contact guidance of osteoblast-like cells was effectively improved by combining surface texturing and deposition of osteocompatible C(3)N(4)-Si coating.

  • 17.
    Mårell, Lena
    Umeå University, Faculty of Medicine, Department of Odontology.
    A multidisciplinary study of patients with signs or symptoms attributed to dental restorative materials2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Anxiety for adverse health effects attributed to dental restorative materials especially dentalamalgam, have been discussed extensively off and on the last 30 years. The possible health effect ofamalgam and health effect of replacements of amalgam, have been extensively studied but theresults are inconclusive and the etiology of the reactions are not entirely elucidated. Furthermore,the question of psychological influence on symptoms attributed to dental restorative materials hasbeen raised and need further examination.

    The aims of this thesis were to describe the change in health over time for patient with symptomsattributed to their dental materials and to determine whether replacement of their dentalrestorative materials had any impact on their perceived health. Furthermore, to determine anddescribe the personality, self-image, level of psychological symptoms and stress among thesepatients and compare the results with those of healthy controls. Finally, to evaluate regression ofLichenoid Contact Reactions and Oral lichen Planus after replacement of the dental materials.

    A questionnaire was mailed to 614 patients that had been referred to the School of Dentistry, Umeå,Sweden with symptoms attributed to dental materials. Among these patients a subgroup with orallichen also underwent a clinical examination at follow-up.

    The result showed that patients with complex symptoms had a more unfavorable long-termprognosis concerning persistent complaints than those with local symptoms only. The oralsymptoms had decreased between baseline and follow-up and the general symptoms had increased.The increase in general symptoms was contradictory since many patients experienced healthimprovement after removal of their dental restorative materials. Concerning personality thepatients was characterized mainly by high persistence and by high fatigability and asthenia as wellas psychosocially learned high self-acceptance. Regarding self-image, both patients with LocalSymptoms Only and patients with Multi Symptoms, scored significantly higher on "spontaneous"and "positive self-image" than the reference group. The Multi symptoms group scored significantlyhigher on psychological symptoms compared to the reference group. However, the Local symptomsgroup did not differ from the references. The remission of oral lesions was after an exchange ofdental materials was seen to a greater extent in patients with Lichenoid Contact Reaction than inpatients with Oral Lichen Planus. Regarding psychological parameters, there were no significantdifferences between the groups.

    In conclusion symptoms related to dental restorative materials seem to be multi-factorial wheredental, medical, social, and psychological factors may be involved. Patient with complex symptomshave a more unfavorable prognosis than patient with local symptoms only. Patient with symptomsself-related to their dental materials may feel improvement in general health after an exchange ofdental materials. The group of patients seems to represent personalities that could be vulnerable inthe demanding modern society, and the various mental and somatic symptoms can be interpretedas attributed to dental fillings. Patients with Local Symptoms or Multi Symptoms are equalconcerning self-image, they are impulsive with an elevated positive self-image, that can result indifficulties in setting limits. Thus in combination with high demands may result in mental stress.The Multi Symptoms group was more psychologically stressed than the group with Local SymptomsOnly and the references. Therefore, before an exchange of dental materials is commenced inpatients with oral lichenoid lesions, a correct diagnosis is needed.

  • 18.
    Mårell, Lena
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Bergdahl, Jan
    Umeå University, Faculty of Social Sciences, Department of Psychology. Department of Clinical Dentistry, University of Tromsø, Tromsø, Norway.
    Tillberg, Anders
    Umeå University, Faculty of Social Sciences, Department of Psychology. Public Dental Health Competence Centre for Northern Norway, Tromsø, Norway.
    Stenberg, Berndt
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
    Berglund, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Psychological symptoms and self-image of patients with complaints attributed to dental restorative materials2019In: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 23, no 6, p. 2805-2811Article in journal (Refereed)
    Abstract [en]

    Objectives: The aim was to study self-image and the level of psychological symptoms in patients with symptoms attributed to their dental restorative materials.

    Materials and methods: A questionnaire containing questions regarding dental and medical history was answered by 257 participants, one group with local oral symptoms only (LSO), and one group with multi-symptoms (M-S). A reference group was randomly selected from a research database at the Department of Psychology, Umeå University, Sweden. The self-image was assessed using the Structural Analysis of Social Behavior (SASB). Psychological symptoms such as somatization, depression, and anxiety were assessed using the Symptom Check List 90 (SCL-90) and the Global Severity Index (GSI) was used to determine the level of psychological symptoms.

    Results: SASB showed that the M-S group and the LSO-group scored significantly higher on the Bspontaneous^ and Bpositive self-image^ than the reference group. In the SCL-90, the M-S group scored significantly higher than the LSO-group and the references on the somatization subscales. On depression, anxiety, and the GSI scale, the M-S group scored significantly higher than the reference group.

    Conclusions: The two subgroups scored significantly higher on the SASB Spontaneous and Positive clusters which indicates that these patients have an excessively positive self-image, are very spontaneous and have an overconfidence in themselves compared to the reference group. In the M-S group there was a clear tendency to somatization, depression, and anxiety and they were more psychologically stressed than the reference group.

    Clinical relevance: Among the patients with illness attributed to their dental materials, the M-S-patients had a significantly higher level of general psychological distress and somatization than the control group which may lead to mental stress.

  • 19.
    Novikova, Liudmila N.
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Kolar, Mallappa K.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Ullrich, Andreas
    Oberhoffner, Sven
    Renardy, Monika
    Doser, Michael
    Müller, Erhard
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Novikov, Lev N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Trimethylene carbonate-caprolactone conduit with poly-p-dioxanone microfilaments to promote regeneration after spinal cord injury2018In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 66, p. 177-191Article in journal (Refereed)
    Abstract [en]

    Spinal cord injury (SCI) is often associated with scarring and cavity formation and therefore bridging strategies are essential to provide a physical substrate for axonal regeneration. In this study we investigated the effects of a biodegradable conduit made from trimethylene carbonate and c-caprolactone (TC) containing poly-p-dioxanone microfilaments (PDO) with longitudinal grooves on regeneration after SCI in adult rats. In vitro studies demonstrated that different cell types including astrocytes, meningeal fibroblasts, Schwann cells and adult sensory dorsal root ganglia neurons can grow on the TC and PDO material. For in vivo experiments, the TC/PDO conduit was implanted into a small 2-3 mm long cavity in the C3-C4 cervical segments immediately after injury (acute SCI) or at 2-5 months after initial surgery (chronic SCI). At 8 weeks after implantation into acute SCI, numerous 5HT-positive descending raphaespinal axons and sensory CGRP-positive axons regenerated across the conduit and were often associated with PDO microfilaments and migrated host cells. Implantation into chronically injured SCI induced regeneration mainly of the sensory CGRP-positive axons. Although the conduit had no effect on the density of OX42-positive microglial cells when compared with SCI control, the activity of GFAP-positive astrocytes was reduced. The results suggest that a TC/PDO conduit can support axonal regeneration after acute and chronic SCI even without addition of exogenous glial or stem cells.

  • 20.
    Ouasti, Sihem
    et al.
    University of Manchester.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. University of Manchester.
    Terenghi, Giorgio
    University of Manchester.
    Tirelli, Nicola
    University of Manchester.
    The CD44/integrins interplay and the significance of receptor binding and re-presentation in the uptake of RGD-functionalized hyaluronic acid2012In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 33, no 4, p. 1120-1134Article in journal (Refereed)
    Abstract [en]

    We have studied the interplay between two endocytic receptors for a carrier structure bearing two complementary ligands. Hyaluronic acid (HA; three different molecular weights) was functionalized with an RGD-containing peptide; this ancillary ligand allows the macromolecule to bind to alpha(v) integrins in addition to the classical HA internalization receptor (CD44). The uptake of HA-RGD and of native HA was assessed in a phagocytic cell model (J774.2 murine macrophages), studying the kinetics of internalization and its mechanistic details. Indications of a synergic binding to integrins and CD44 emerged for HA-RGD; possibly, a first binding to integrins allows for a pre-concentration of the macromolecule on the cell surface, which is then followed by its binding to CD44. The endocytic mechanism and kinetics appeared then dominated by CD44, which has a much slower turnover than integrins. In this study we have demonstrated that the knowledge of the rate-determining steps of the internalization of a carrier is necessary for assessing its performance. In this case, the presence of multiple ligands on a carrier was beneficial in some respect (e.g. in improved binding/targeting), but may not be sufficient to overcome penetration barriers that arise from slow receptor re-presentation. (C) 2011 Elsevier Ltd. All rights reserved.

  • 21.
    Persson-Sjögren, Solveig
    et al.
    Umeå University, Faculty of Medicine, Integrative Medical Biology.
    Sjögren, Göran
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Effects of dental materials on insulin release from isolated islets of Langerhans2002In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 18, no 1, p. 20-25Article in journal (Refereed)
    Abstract [en]

    Objectives: To investigate the possibility of using a whole organ model for evaluating the biological effects of dental restoration materials in vitro.

    Methods: The effect on insulin release of isolated Langerhans islets of a series of dental materials was examined. The islets were incubated for 1 h with extracts obtained from various dental materials and insulin was assayed radioimmunologically with crystalline mouse insulin. The results were analysed statistically using analysis of variance (ANOVA) and Scheffe's test at a significance level of p<0.05.

    Results: One dental ceramic, Vita VMK 95, significantly ( p<0.01) decreased the insulin release, whereas another dental ceramic, Empress ( p<0.01), a partly re-cast high-noble gold alloy ( p<0.001), a modified high-noble gold alloy ( p<0,05), and unalloyed copper ( p<0.001) significantly increased the release of insulin.

    Significance: The results demonstrate a new instance of examining the biological effects of dental restoration materials. The method provides information about the effect of different materials on organ level in vitro that can complement other in vitro tests.

  • 22.
    Pulkkinen, Hertta
    et al.
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Tiitu, Virpi
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Lammentausta, Eveliina
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Laasanen, Mikko
    Department of Physics, University of Kuopio, Kuopio, Finland.
    Hämäläinen, Eija-Riitta
    Bioprocess Engineerng Laboratory, Department of Process and Environmental Engineering, University of Oulu, Oulu, Finland.
    Kiviranta, Ilkka
    Jyväskylä Central Hospital, Jyväskylä, Finland.
    Lammi, Mikko
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland.
    Cellulose sponge as a scaffold for cartilage tissue engineering.2006In: Bio-medical materials and engineering, ISSN 0959-2989, E-ISSN 1878-3619, Vol. 16, no 4 Suppl, p. S29-S35, article id 16823110Article in journal (Refereed)
    Abstract [en]

    One goal of functional tissue engineering is to manufacture scaffolds infiltrated with chondrocytes which are suitable for transplantation into the lesion areas of articular cartilage. Various research strategies are used to fabricate cartilage transplants which would have the correct phenotype, contain enough extracellular matrix components, and have structural and biomechanical properties equivalent to normal articular cartilage. We have investigated the suitability of viscose cellulose sponges as a scaffold for cartilage tissue engineering. The sponges were tested alone, or with recombinant human type II collagen cross-linked inside the material. Scanning electron microscopy and confocal microscopy were used to study the structure of the scaffold during four weeks of cultivation. Cellulose and cellulose/recombinant type II collagen sponges were biocompatible for at least four weeks in cultivation, and gradual filling of the scaffold was observed. However, the constructs remained soft during the observation period, and were devoid of extracellular matrix composition typical for normal articular cartilage.

  • 23.
    Pulkkinen, Hertta
    et al.
    Institute of Biomedicine, Anatomy, University of Eastern Finland, Kuopio, Finland.
    Tiitu, Virpi
    Institute of Biomedicine, Anatomy, University of Eastern Finland, Kuopio, Finland.
    Valonen, Pia
    Institute of Biomedicine, Anatomy, University of Eastern Finland, Kuopio, Finland.
    Jurvelin, Jukka
    Department of Physics and Mathematics, University of Eastern Finland, Kuopio, Finland.
    Lammi, Mikko
    Department of Biosciences, University of Eastern Finland, Kuopio, Finland; Biocenter Kuopio, University of Eastern Finland, Kuopio, Finland.
    Kiviranta, Ilkka
    Department of Orthopaedics and Traumatology, University of Helsinki, Helsinki, Finland; Department of Orthopaedics and Traumatology, Jyväskylä Central Hospital, Jyväskylä, Finland.
    Engineering of cartilage in recombinant human type II collagen gel in nude mouse model in vivo.2010In: Osteoarthritis and Cartilage, ISSN 1063-4584, E-ISSN 1522-9653, Vol. 18, no 8, p. 1077-1087, article id 20472086Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Our goal was to test the recombinant human type II collagen (rhCII) material as a gel-like scaffold for chondrocytes in a nude mouse model in vivo.

    DESIGN: Isolated bovine chondrocytes (6x10(6)) were seeded into rhCII gels (rhCII-cell) and injected subcutaneously into the backs of nude mice. For comparison, chondrocytes (6x10(6)) in culture medium (Med-cell) and cell-free rhCII gels (rhCII-gel) were similarly injected (n=24 animals, total of three injections/animal). After 6 weeks, the tissue constructs were harvested and analyzed.

    RESULTS: Chondrocytes with or without rhCII-gel produced white resilient tissue, which in histological sections had chondrocytes in lacunae-like structures. Extracellular matrix stained heavily with toluidine blue stain and had strongly positive collagen type II immunostaining. The tissue did not show any evidence of vascular invasion or mineralization. The cell-free rhCII-gel constructs showed no signs of cartilage tissue formation. Cartilage tissue produced by Med-cell was thin and macroscopically uneven, while the rhCII-cell construct was smooth and rounded piece of neotissue. RhCII-cell constructs were statistically thicker than Med-cell ones. However, no statistical differences were found between the groups in terms of glycosaminoglycan (GAG) content or biomechanical properties.

    CONCLUSIONS: These results show that rhCII-gel provides good expansion and mechanical support for the formation of cartilage neotissue. RhCII material may allow favorable conditions in the repair of chondral lesions.

  • 24.
    Pulkkinen, Hertta
    et al.
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland; Department of Orthopaedics and Traumatology, Jyväskylä Central Hospital, Jyväskylä, Finland.
    Tiitu, Virpi
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland; Department of Orthopaedics and Traumatology, Jyväskylä Central Hospital, Jyväskylä, Finland.
    Valonen, Piia
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland; Department of Orthopaedics and Traumatology, Jyväskylä Central Hospital, Jyväskylä, Finland.
    Hämäläinen, Eija-Riitta
    Bioprocess Engineering Laboratory, University of Oulu, Oulu, Finland.
    Lammi, Mikko
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio, Finland; Department of Biosciences, Applied Biotechnology, University of Kuopio, Kuopio, Finland.
    Kiviranta, Ilkka
    Department of Orthopaedics and Traumatology, Jyväskylä Central Hospital, Jyväskylä, Finland; Department of Orthopaedics and Traumatology, Helsinki University Hospital, Helsinki, Finland.
    Recombinant human type II collagen as a material for cartilage tissue engineering.2008In: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 31, no 11, p. 960-969, article id 19089798Article in journal (Refereed)
    Abstract [en]

    PURPOSE: Collagen type II is the major component of cartilage and would be an optimal scaffold material for reconstruction of injured cartilage tissue. In this study, the feasibility of recombinant human type II collagen gel as a 3-dimensional culture system for bovine chondrocytes was evaluated in vitro.

    METHODS: Bovine chondrocytes (4x106 cells) were seeded within collagen gels and cultivated for up to 4 weeks. The gels were investigated with confocal microscopy, histology, and biochemical assays.

    RESULTS: Confocal microscopy revealed that the cells maintained their viability during the entire cultivation period. The chondrocytes were evenly distributed inside the gels, and the number of cells and the amount of the extracellular matrix increased during cultivation. The chondrocytes maintained their round phenotype during the 4-week cultivation period. The glycosaminoglycan levels of the tissue increased during the experiment. The relative levels of aggrecan and type II collagen mRNA measured with realtime polymerase chain reaction (PCR) showed an increase at 1 week.

    CONCLUSION: Our results imply that recombinant human type II collagen is a promising biomaterial for cartilage tissue engineering, allowing homogeneous distribution in the gel and biosynthesis of extracellular matrix components.

  • 25.
    Pöllänen, Raimo
    et al.
    BioMater Center, University of Eastern Finland, Kuopio, Finland.
    Tikkanen, Anna-Maria
    BioMater Center, University of Eastern Finland, Kuopio, Finland.
    Lammi, Mikko
    Department of Biomedicine, University of Eastern Finland, Kuopio, Finland; Department of Biosciences, Applied Biotechnology, University of Eastern Finland, Kuopio, Finland.
    Lappalainen, Reijo
    BioMater Center, University of Eastern Finland, Kuopio, Finland; Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    The effect of loading and material on the biomechanical properties and vitality of bovine cartilage in vitro.2011In: Journal of Applied Biomaterials and Biomechanics, ISSN 1722-6899, Vol. 9, no 1, p. 47-53, article id 21445828Article in journal (Refereed)
    Abstract [en]

    PURPOSE: New methodology for long-term (270 h) biomechanical testing with living cartilage was developed. Polyurethane (PU) implant material was compared with stainless steel and reference samples in static unconfined compressive loading conditions on cartilage to provide a basis for dynamic testing of novel PU implant materials under conditions that simulate an articulating human knee joint.

    METHODS: Custom-made tools and techniques were developed to prepare cylindrical samples from bovine patella with cartilage including subchondral bone. Specific incubator cups with static loading setups for a culture incubator were manufactured to keep bovine cartilage explants alive in cell culture conditions under unconfined static compressive loading (0.25 MPa) for 270 h (11.25 d). Four loading conditions of cartilage were studied: free (FREE), restrained minimal loading (RESTR), loading with a metal plate (MEW) and loading with polyurethane (PUW).

    RESULTS: After static loading for 270 h, cartilage biomechanical tests indicated clear differences between the groups in frequency dependent dynamic stiffness curves. Surprisingly, the PU curves were closest to the FREE sample curves. Those with load and direct contact with metal (MEW) became significantly stiffer, while restrained samples became softer. Significant differences (p<0.05, Mann-Whitney's U test) in cell vitality between samples from various groups could be seen in fluorescein diacetate (FDA) and propidium iodide (PI) stained samples by confocal microscopic analysis. The approximate mean percentages of living cells after 270 hours cultivation were: FREE 87%, MEW 3%, PUW 35%, and RESTR 66%. Test results indicate that it is possible to keep cartilage cells alive in cell culture incubator conditions for two weeks period under a 0.25 MPa unconfined static loading. The FREE samples were most successful and cells loaded with PU were more vital than cells loaded with metal.

    CONCLUSIONS: Based on the results, PU seems to be more compatible material than surgical steel in contact with living cartilage. Because of a large variation in the quality of bovine cartilage material from different animals, special care is necessary when selecting specimens to guarantee reliable and reproducible results.

  • 26.
    Qu, Chengjuan
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Department of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital, Kuopio, Finland.
    Kaitainen, Salla
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Kröger, Heikki
    Department of Orthopaedics, Traumatology and Hand Surgery, Kuopio University Hospital, Kuopio, Finland.
    Lappalainen, Reijo
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
    Lammi, Mikko
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Key Laboratory of Trace Elements and Endemic Diseases, National Health and Family Planning Commission, School of Public Health of Health Science Center, Xi’an Jiaotong University, Xi’an, China.
    Behavior of human bone marrow-derived mesenchymal stem cells on various titanium-based coatings2016In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 9, no 10, article id 827Article in journal (Refereed)
    Abstract [en]

    The chemical composition and texture of titanium coatings can influence the growth characteristics of the adhered cells. An enhanced proliferation of the human mesenchymal stem cells (hMSCs) would be beneficial. The present study was aimed to investigate whether titanium deposited at different atmospheres would affect the cell growth properties, cellular morphology, and expression of surface markers of hMSCs. Titanium-based coatings were deposited on silicon wafers under oxygen, nitrogen, or argon atmospheres by ultra-short pulsed laser deposition using two different gas pressures followed by heating at 400 °C for 2 h. The characteristics of the coated surfaces were determined via contact angle, zeta potential, and scanning electron microscopy (SEM) techniques. Human MSCs were cultivated on differently coated silicon wafers for 48 h. Subsequently, the cell proliferation rates were analyzed with an MTT assay. The phenotype of hMSCs was checked via immunocytochemical stainings of MSC-associated markers CD73, CD90, and CD105, and the adhesion, spreading, and morphology of hMSCs on coated materials via SEM. The cell proliferation rates of the hMSCs were similar on all coated silicon wafers. The hMSCs retained the MSC phenotype by expressing MSC-associated markers and fibroblast-like morphology with cellular projections. Furthermore, no significant differences could be found in the size of the cells when cultured on all various coated surfaces. In conclusion, despite certain differences in the contact angles and the zeta potentials of various titanium-based coatings, no single coating markedly improved the growth characteristics of hMSCs.

  • 27. Raina, Deepak Bushan
    et al.
    Qayoom, Irfan
    Larsson, David
    Umeå University, Faculty of Medicine. Lund University, Faculty of Medicine, Department of Clinical Sciences Lund, Orthopedics, Lund 22185, Sweden.
    Zheng, Ming Hao
    Kumar, Ashok
    Isaksson, Hanna
    Lidgren, Lars
    Tagil, Magnus
    Guided tissue engineering for healing of cancellous and cortical bone using a combination of biomaterial based scaffolding and local bone active molecule delivery2019In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 188, p. 38-49Article in journal (Refereed)
    Abstract [en]

    A metaphyseal bone defect due to infection, tumor or fracture leads to loss of cancellous and cortical bone. An animal model separating the cancellous and cortical healing was used with a combination of a macroporous gelatin-calcium sulphate-hydroxyapatite (Gel-CaS-HA) biomaterial as a cancellous defect filler, and a thin collagen membrane (CM) guiding cortical bone regeneration. The membrane was immobilized with bone morphogenic protein-2 (rhBMP-2) to enhance the osteoinductive properties. The Gel-CaS-HA cancellous defect filler contained both rhBMP-2 and a bisphosphonate, (zoledronate = ZA) to prevent premature callus resorption induced by the pro-osteoclast effect of rhBMP-2 alone. In the first part of the study, the CM delivering both rhBMP-2 and ZA was tested in a muscle pouch model in rats and the co-delivery of rhBMP-2 and ZA via the CM resulted in higher amounts of bone compared to rhBMP-2 alone. Secondly, an established tibia defect model in rats was used to study cortical and cancellous bone regeneration. The defect was left empty, filled with Gel-CaS-HA alone, Gel-CaS-HA immobilized with ZA or Gel-CaS-HA immobilized with rhBMP-2+ ZA. Functionalization of the Gel-CaS-HA scaffold with bioactive molecules produced significantly more bone in the cancellous defect and its surroundings but cortical defect healing was delayed likely due to the protrusion of the Gel-CaS-HA into the cortical bone. To guide cortical regeneration, the cortical defect was sealed endosteally by a CM with or without rhBMP-2. Subsequently, the cancellous defect was filled with Gel-CaS-HA containing ZA and rhBMP2 + ZA. In the groups where the CM was doped with rhBMP-2, significantly higher number of cortices bridged. The approach to guide cancellous as well as cortical bone regeneration separately in a metaphyseal defect using two bioactive molecule immobilized biomaterials is promising and could improve the clinical care of patients with metaphyseal defects.

  • 28.
    Ramstedt, Madeleine
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ribeiro, Isabel A. C.
    Bujdakova, Helena
    Mergulhão, Filipe J. M.
    Jordao, Luisa
    Thomsen, Peter
    Alm, Martin
    Burmølle, Mette
    Vladkova, Todorka
    Can, Fusun
    Reches, Meital
    Riool, Martijn
    Barros, Alexandre
    Reis, Rui L.
    Meaurio, Emilio
    Kikhney, Judith
    Moter, Annette
    Zaat, Sebastian A. J.
    Sjollema, Jelmer
    Evaluating Efficacy of Antimicrobial and Antifouling Materials for Urinary Tract Medical Devices: Challenges and Recommendations2019In: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 19, no 5, article id 1800384Article, review/survey (Refereed)
    Abstract [en]

    In Europe, the mean incidence of urinary tract infections in intensive care units is 1.1 per 1000 patient‐days. Of these cases, catheter‐associated urinary tract infections (CAUTI) account for 98%. In total, CAUTI in hospitals is estimated to give additional health‐care costs of £1–2.5 billion in the United Kingdom alone. This is in sharp contrast to the low cost of urinary catheters and emphasizes the need for innovative products that reduce the incidence rate of CAUTI. Ureteral stents and other urinary‐tract devices suffer similar problems. Antimicrobial strategies are being developed, however, the evaluation of their efficacy is very challenging. This review aims to provide considerations and recommendations covering all relevant aspects of antimicrobial material testing, including surface characterization, biocompatibility, cytotoxicity, in vitro and in vivo tests, microbial strain selection, and hydrodynamic conditions, all in the perspective of complying to the complex pathology of device‐associated urinary tract infection. The recommendations should be on the basis of standard assays to be developed which would enable comparisons of results obtained in different research labs both in industry and in academia, as well as provide industry and academia with tools to assess the antimicrobial properties for urinary tract devices in a reliable way.

  • 29.
    Sjögren, Göran
    et al.
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Lantto, Rolf
    Granberg, Åsa
    Sundström, Bengt-Olov
    Tillberg, Anders
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Clinical examination of leucite-reinforced glass-ceramic crowns (Empress) in general practice: a retrospective study1999In: International Journal of Prosthodontics, ISSN 0893-2174, E-ISSN 1139-9791, Vol. 12, no 2, p. 122-128Article in journal (Refereed)
    Abstract [en]

    PURPOSE: The purpose of this study was to retrospectively evaluate leucite reinforced-glass ceramic crowns (Empress) placed in patients who regularly visit general practices. MATERIALS AND METHODS: One hundred ten Empress crowns, placed in 29 patients who visited a general practice on a regular basis, were evaluated according to the California Dental Association's (CDA) quality evaluation system. In addition, the occurrence of plaque and certain gingival conditions was evaluated. All crowns were luted with resin composite cement. The mean and median years in function for the crowns were 3.6 and 3.9 years, respectively. RESULTS: Based on the CDA criteria, 92% of the 110 crowns were rated "satisfactory." Eighty-six percent were given the CDA rating "excellent" for margin integrity. Fracture was registered in 6% of the 110 crowns. Of the remaining 103 crowns, the CDA rating excellent was given to 74% for anatomic form, 86% for color, and 90% for surface. No significant differences (P > 0.05) were observed regarding fracture rates between anterior and posterior crowns. With regard to the occurrence of plaque and bleeding on probing, no significant differences (P > 0.05) were observed between the Empress crowns and the controls. CONCLUSION: Most of the fractured crowns had been placed on molars or premolars. Although the difference between anterior and posterior teeth was not statistically significant with respect to the fracture rates obtained, the number of fractured crowns placed on posterior teeth exceeded that of those placed on anterior teeth. The difference between the fracture rates may have clinical significance, and the risk of fracture has to be taken into consideration when placing crowns on teeth that are likely to be subjected to high stress levels.

  • 30.
    Sjögren, Göran
    et al.
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Lantto, Rolf
    Tillberg, Anders
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Clinical evaluation of all-ceramic crowns (Dicor) in general practice.1999In: The Journal of prosthetic dentistry (Print), ISSN 0022-3913, E-ISSN 1097-6841, Vol. 81, no 3, p. 277-284Article in journal (Refereed)
    Abstract [en]

    STATEMENT OF PROBLEM: There are few studies regarding all-ceramic full crowns placed by general practitioners; however, most dental restorations are carried out by general practitioners, and their clinical performance may be of particular interest. PURPOSE: Ninety-eight all-ceramic Dicor crowns placed in 46 patients regularly visiting a general practice were evaluated with the California Dental Association's (CDA) criteria. Mean and median ages of the crowns were 6.1 and 5.8 years, respectively (range 1.4 to 10. 9 years). Crowns were luted with either a glass ionomer, zinc phosphate, or resin composite cement. RESULTS. Of the 98 crowns, 82% were rated satisfactory. For marginal integrity, 51% were rated excellent. Fracture was registered in 14 all crowns, and 1 endodontically treated tooth with a Dicor crown was extracted because of root fracture; of the remaining 83 crowns, 55% were rated excellent for color. Corresponding figures for surface and anatomic form were 46% and 23%, respectively. The most common finding was slightly rough surfaces (64%). No statistically significant difference was observed for fracture rates obtained when the crowns luted with different luting agents were compared (P >.05). There was no more plaque or bleeding on probing (P >.05) in connection with the Dicor crowns than in the control surfaces.

  • 31.
    Sjögren, Göran
    et al.
    Umeå University, Faculty of Medicine, Odontology, Dental Materials Science.
    Sletten, Gaynour
    Scandinaivian Institute of Dental Materials, Haslum, Norway.
    Dahl, Jon E
    Scandinaivian Institute of Dental Materials, Haslum, Norway.
    Cytotoxicity of dental alloys, metals, and ceramics assessed by millipore filter, agar overlay, and MTT tests.2002In: The Journal of Prosthetic Dentistry, ISSN 0022-3913, Vol. 84, no 2, p. 229-236Article in journal (Refereed)
    Abstract [en]

    Statement of Problem: Biocompatibility of dental materials is dependent on the release of elements from the materials. In addition, the composition, pretreatment, and handling of the materials influence the element release. Purpose: This study evaluated the cytotoxicity of dental alloys, metals, and ceramics, with specific emphasis on the effects of altering the composition and the pretreatment. Material and Methods: By using cells from a mouse fibroblast cell line and the agar overlay test, Millipore filter test, and MTT test, cytotoxicity of various metals, metal alloys, and ceramics for dental restoration were studied. Effects of altering the composition of a high noble gold alloy and of pretreatment of a ceramic-bonding alloy were also studied. In addition, the release of elements into the cell culture medium by the materials studied was measured using an inductively coupled plasma optical emission spectrophotometer. The results of the MTT test were analyzed statistically using ANOVA and Scheffé test at a significance level of P<.05. Results: Specimens manufactured from materials intended for dental restorations and handled in accordance with the manufacturers’ instructions were ranked from “noncytotoxic” to “mildly cytotoxic” according to the agar overlay and Millipore filter tests. For the MTT test, no significant differences were observed between these materials and controls, with the exception of JS C-gold and unalloyed titanium. The modified materials were ranked from “mildly cytotoxic” to “moderately cytotoxic” in the agar overlay and Millipore filter tests and from “noncytotoxic” to “moderately cytotoxic” in the MTT test. Thus, cytotoxicity was related to the alloy composition and treatment. The release of Cu and Zn seemed to be important for the cytotoxic effect. Conclusion: Alterations in the composition and the pretreatment can greatly influence the cytotoxicity, and the results stress the importance of carefully following the manufacturers’ instructions when handling dental materials.

  • 32. Sun, M
    et al.
    Kingham, Paul J
    Blond McIndoe Laboratories, School of Medicine, Stopford Building, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom.
    Reid, Adam J
    Armstrong, Stephanie J
    Terenghi, Giorgio
    Downes, S
    In vitro and in vivo testing of novel ultrathin PCL and PCL/PLA blend films as peripheral nerve conduit2010In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 93, no 4, p. 1470-1481Article in journal (Refereed)
    Abstract [en]

    In an attempt to obviate the drawbacks of nerve autograft, ultrathin microporous biodegradable PCL and PCL/PLA films were tested for their compatibility with motor neuron-like NG108-15 cells and primary Schwann cells. Data obtained from MTS colorimetric and DNA fluorimetric assays showed that both cell lines readily attached and proliferated on these materials. Images taken using scanning electron microscope and fluorescence microscope confirmed these observations. Enhanced cell-surface interaction was achieved by pretreating the films in NaOH solution. Importantly, NG108-15 cells could be induced into differentiated phenotype with long, un-branched neurites growing across the surface of the materials. The bipolar spindle-shaped phenotype of Schwann cells was also retained on these scaffolds. Positive immunochemical staining using antibodies against neurofilament for NG108-15 cells and S100 for Schwann cells indicated the expression of these marker proteins. In a small-scaled pilot testing, the performance of PCL conduits in bridging up a 10 mm gap in rat sciatic nerve model was assessed. Immunohistochemical staining showed that regenerated nerve tissue and penetrated Schwann cells have the potential to span the whole length of the conduit in 2 weeks.

  • 33.
    Sundh, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Molin, Margareta
    Umeå University, Faculty of Medicine, Department of Odontology, Prosthetic Dentistry.
    Sjögren, Göran
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    Fracture resistance of yttrium oxide partially-stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing2005In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 21, no 5, p. 476-482Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: Yttria-stabilized zirconia (Y-TZP) ceramic is a high-performance material with excellent mechanical properties suitable for fixed partial dentures. The purpose of this study was to evaluate after fatigue testing, the effect of heat-treatment and veneering on the fracture resistance of frameworks manufactured using sintered and subsequently hot isostatic pressed yttrium oxide partially-stabilized zirconia (Denzir).

    METHODS: The specimens were subjected to dynamic loading in water. Thereafter, using a universal testing machine, the fracture resistance of three-unit fixed partial dentures was determined; (i) of the frameworks as delivered after machining, (ii) after the frameworks had been subjected to heat-treatment similar to veneering with a glass-ceramic (Eris) or a feldspar-based ceramic (Vita D) and (iii) after the frameworks had been veneered with these ceramics. In addition, the fracture resistance of frameworks as delivered after machining not subjected to dynamic loading in water was determined.

    RESULTS: Cyclic loading in water did not significantly (p>0.05) affect the fracture resistance. The load necessary to fracture the frameworks as delivered after machining was significantly (p<0.001) higher than for the heat-treated and veneered specimens. No significant difference was seen between the specimens veneered with Eris and those veneered with Vita D (p>0.05). For all but three specimens the fractures were located in the loading point and through one of the connectors.

    SIGNIFICANCE: Heat-treatment and veneering reduce fracture resistance of hot isostatic pressed zirconia. Nevertheless, the results obtained indicate that it is an interesting material for potential in all-ceramic restorations.

  • 34.
    Sundh, Anders
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    Sjögren, Göran
    Umeå University, Faculty of Medicine, Department of Odontology, Dental Materials Science.
    Fracture resistance of all-ceramic zirconia bridges with differing phase stabilizers and quality of sintering2006In: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 22, no 8, p. 778-784Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: The mechanical properties of zirconia ceramics are affected of stabilizing oxides and quality of sintering. The purpose of this study was to investigate the fracture resistance of frameworks manufactured using prefabricated zirconia blanks with differing stabilizing oxides and quality of sintering.

    METHODS: After dynamic loading in water, the fracture resistance was determined of stylized three-unit fixed partial dentures made of prefabricated homogenous ceramic green-body yttria-stabilized zirconia (Y-TZP) blanks (Vita YZ) or of densely-sintered magnesia partially stabilized zirconia (Mg-PSZ) blanks (Denzir-M); (i) as supplied from the manufacturer, (ii) after subjection to heat treatment in a way similar to veneering, and (Hi) after veneering with a feldspar-based ceramic.

    RESULTS: After veneering, the load at fracture of the Vita YZ specimens was significantly higher (p<0.05) than that of Denzir-M. The load necessary to fracture Denzir-M as supplied after machining was significantly (p<0.05) higher than that of heat-treated Denzir-M, Vita YZ as supplied and heat-treated Vita YZ specimens. There was no significant difference (p>0.05) between the heat-treated and veneered Denzir-M specimens. For Vita YZ the load at fracture of the veneered specimens was significantly (p<0.05) higher than of those as supplied or heat-treated, whereas no significant difference (p>0.05) was seen between heat-treated Vita YZ and Vita YZ specimens as supplied.

    SIGNIFICANCE: The fracture strength of the Vita YZ specimens increased considerably after veneering. Denzir-M and Vita YZ seem to be interesting alternatives for use as core materials in all-ceramic restorations. Long-term studies are, however, necessary before general clinical recommendations can be issued.

  • 35.
    Säämänen, Anna-Marja
    et al.
    Department of Biomedicine, Medical Biochemistry and Genetics, University of Turku, Turku, Finland.
    Vasara, Anna
    Helsinki University Hospital, Helsinki, FInland.
    Lammi, Mikko
    Department of Biosciences, APplied Biotechnology, University of Kuopio, Kuopio, Finland.
    Kiviranta, Ilkka
    University of Helsinki, Helsinki, Finland; Helsinki University Hospital, Helsinki, Finland.
    Rustovamman kirurginen korjaaminen solusiirteiden ja biomateriaalien avulla [Orthopaedic repair of cartilage injury by cellular implants and biomaterials]2008In: Duodecim, ISSN 0012-7183, E-ISSN 2242-3281, Vol. 124, no 16, p. 1910-1918Article, review/survey (Refereed)
    Abstract
  • 36.
    Tiitu, Virpi
    et al.
    Institute of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland.
    Pulkkinen, Hertta
    Institute of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland.
    Valonen, Piia
    Institute of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland.
    Kiviranta, Outi
    Institute of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland.
    Kiekara, Teemu
    Institute of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland.
    Kiviranta, Ilkka
    Helsinki University Hospital, Department of Orthopaedics and Traumatology, Helsinki, Finland; Jyväskylä Central Hospital, Department of Orthopaedics and Traumatology, Jyväskylä, Finland.
    Lammi, Mikko
    Institute of Biomedicine, Anatomy, University of Kuopio, Kuopio, Finland; Biocenter Kuopio and Department of Biosciences, Applied Biotechnology, University of Kuopio, Kuopio, Finland.
    Recombinant human collagens as scaffold materials for chondrocyte cultures.2008In: Bio-medical materials and engineering, ISSN 0959-2989, E-ISSN 1878-3619, Vol. 18, no 4-5, p. 225-229, article id 19065026Article in journal (Refereed)
    Abstract
  • 37.
    Tiitu, Virpi
    et al.
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio; Jyväskylä Central Hospital, Jyväskylä, Finland.
    Pulkkinen, Hertta
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio; Jyväskylä Central Hospital, Jyväskylä, Finland.
    Valonen, Piia
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio; Jyväskylä Central Hospital, Jyväskylä, Finland.
    Pulliainen, Outi
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio.
    Kellomäki, Minna
    Tampere University of Technology, Tampere, Finland.
    Lammi, Mikko
    Institute of Biomedicine, Department of Anatomy, University of Kuopio, Kuopio; Department of Biosciences, Applied Biotechnology, University of Kuopio, Kuopio, Finland.
    Kiviranta, Ilkka
    Department of Orthopaedics and Traumatology, Helsinki University Hospital, Helsinki, Finland.
    Bioreactor improves the growth and viability of chondrocytes in the knitted poly-L,D-lactide scaffold.2008In: Biorheology, ISSN 0006-355X, E-ISSN 1878-5034, Vol. 45, no 3-4, p. 539-546, article id 18836252Article in journal (Refereed)
    Abstract [en]

    In the present study bovine chondrocytes were cultured in two different environments (static flasks and bioreactor) in knitted poly-L,D-lactide (PLDLA) scaffolds up to 4 weeks. Chondrocyte viability was assessed by employing cell viability fluorescence markers. The cells were visualized using confocal laser scanning microscopy and scanning electron microscopy. The mechanical properties and uronic acid contents of the scaffolds were tested. Our results showed that cultivation in a bioreactor improved the growth and viability of the chondrocytes in the PLDLA scaffolds. Cells were observed both on and in between the fibrils of scaffold. Furthermore, chondrocytes cultured in the bioreactor, regained their original round phenotypes, whereas those in the static flask culture were flattened in shape. Confocal microscopy revealed that chondrocytes from the bioreactor were attached on both sides of the scaffold and sustained viability better during the culture period. Uronic acid contents of the scaffolds, cultured in bioreactor, were significantly higher than in those cultured in static flasks for 4 weeks. In summary, our data suggests that the bioreactor is superior over the static flask culture when culturing chondrocytes in knitted PLDLA scaffold.

  • 38. Trentin, Danielle S
    et al.
    Silva, Denise B
    Frasson, Amanda P
    Rzhepishevska, Olena
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    da Silva, Márcia V
    Pulcini, Elinor de L
    James, Garth
    Soares, Gabriel V
    Tasca, Tiana
    Ramstedt, Madeleine
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Giordani, Raquel B
    Lopes, Norberto P
    Macedo, Alexandre J
    Natural green coating inhibits adhesion of clinically important bacteria2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, p. 8287-Article in journal (Refereed)
    Abstract [en]

    Despite many advances, biomaterial-associated infections continue to be a major clinical problem. In order to minimize bacterial adhesion, material surface modifications are currently being investigated and natural products possess large potential for the design of innovative surface coatings. We report the bioguided phytochemical investigation of Pityrocarpa moniliformis and the characterization of tannins by mass spectrometry. It was demonstrated that B-type linked proanthocyanidins-coated surfaces, here termed Green coatings, reduced Gram-positive bacterial adhesion and supported mammalian cell spreading. The proposed mechanism of bacterial attachment inhibition is based on electrostatic repulsion, high hydrophilicity and the steric hindrance provided by the coating that blocks bacterium-substratum interactions. This work shows the applicability of a prototype Green-coated surface that aims to promote necessary mammalian tissue compatibility, while reducing bacterial colonization.

  • 39.
    Tse, Kai-Hei
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Sun, Mingzhu
    University of Manchester.
    Mantovani, Cristina
    University of Manchester.
    Terenghi, Giorgio
    University of Manchester.
    Downes, Sandra
    University of Manchester.
    Kingham, Paul J
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    In vitro evaluation of polyester-based scaffolds seeded with adipose derived stem cells for peripheral nerve regeneration2010In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 95, no 3, p. 701-708Article in journal (Refereed)
    Abstract [en]

    To overcome the disadvantages of autografts for peripheral nerve repair, different methods such as artificial nerve conduits have been investigated for an alternative approach. This study demonstrated that solvent casting is a simple but efficient method to create thin polyester-based scaffolds for stem cell delivery. Using poly (ε-caprolactone) and poly (D,L-lactic acid), we produced scaffold films containing heterogenous depressions (pits) on the air surface with a size ranging from 0.5 to 30 μm(2). These scaffolds were moderately hydrophobic; however, they supported the differentiation of adipose derived stem cells (ADSC) into a Schwann cell-like phenotype. The differentiated ADSC (dADSC) expressed S100 protein and glial fibrillary acidic protein and readily adhered to the films and proliferated at a similar rate to those cultured on tissue culture polystyrene. Cells were also positive for proliferating cell nuclear antigen. Furthermore, dADSC retained functional activity and significantly enhanced neurite outgrowth from dorsal root ganglia neurons. This study suggests polymer scaffolds combined with dADSCs could be a promising therapy for peripheral nerve injuries.

  • 40. Turunen, Siru
    et al.
    Lammi, Mikko
    Department of Biosciences, University of Eastern Finland, Kuopio, Finland; Biocenter Kuopio, University of Eastern Finland, Kuopio, Finland.
    Saarakkala, Simo
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; Department of Diagnostic Radiology, University of Oulu and Oulu University Hospital, Oulu, Finland .
    Koistinen, Arto
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland; BioMater Centre, University of Eastern Finland, Kuopio, Finland.
    Korhonen, Rami
    Department of Applied Physics, University of Eastern Finland, Kuopio, Finland .
    Hypotonic challenge modulates cell volumes differently in the superficial zone of intact articular cartilage and cartilage explant.2012In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940, Vol. 11, no 5, p. 665-75, article id 21877192Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to evaluate the effect of sample preparation on the biomechanical behaviour of chondrocytes. We compared the volumetric and dimensional changes of chondrocytes in the superficial zone (SZ) of intact articular cartilage and cartilage explant before and after a hypotonic challenge. Calcein-AM labelled SZ chondrocytes were imaged with confocal laser scanning microscopy through intact cartilage surfaces and through cut surfaces of cartilage explants. In order to clarify the effect of tissue composition on cell volume changes, Fourier Transform Infrared microspectroscopy was used for estimating the proteoglycan and collagen contents of the samples. In the isotonic medium (300 mOsm), there was a significant difference (p < 0.05) in the SZ cell volumes and aspect ratios between intact cartilage samples and cartilage explants. Changes in cell volumes at both short-term (2 min) and long-term (2 h) time points after the hypotonic challenge (180 mOsm) were significantly different (p < 0.05) between the groups. Further, proteoglycan content was found to correlate significantly (r(2) = 0.63, p < 0.05) with the cell volume changes in cartilage samples with intact surfaces. Collagen content did not correlate with cell volume changes. The results suggest that the biomechanical behaviour of chondrocytes following osmotic challenge is different in intact cartilage and in cartilage explant. This indicates that the mechanobiological responses of cartilage and cell signalling may be significantly dependent on the integrity of the mechanical environment of chondrocytes.

  • 41.
    Vasara, Anna
    et al.
    Department of Orthopaedics and Traumatology, Helsinki University Hospital, Helsinki, Finland.
    Hyttinen, Mika
    Department of Anatomy, University of Kuopio, Kuopio, Finland .
    Lammi, Mikko
    Department of Anatomy, University of Kuopio, Kuopio, Finland .
    Lammi, Pirkko
    Department of Anatomy, University of Kuopio, Kuopio, Finland .
    Långsjö, Teemu
    Department of Anatomy, University of Kuopio, Kuopio, Finland .
    Lindahl, Anders
    Institute of Laboratory Medicine, Department of Clinical Chemistry and Transfusion Medicine, Göteborg University, Gothenburg, Sweden.
    Peterson, Lars
    Institution of Orthopaedics, Göteborg University, Gothenburg, Sweden .
    Kellomäki, Minna
    Institue for Biomaterials, Tampere University of Technology, Tampere, Finland.
    Konttinen, Yrjö
    Department of Medicine, Invärtes Medicine, Helsinki University Hospital, Helsinki, Finland; ORTON Research Institute, Invalid Foundation, Helsinki, Finland; Department of Anatomy, University of Helsinki, Finland.
    Helminen, Heikki
    Department of Medicine, Invärtes Medicine, Helsinki University Hospital and ORTON Research Institute, Invalid Foundation, Helsinki and Department of Anatomy, University of Helsinki, Finland.
    Kiviranta, Ilkka
    Department of Surgery, Jyväskylä Central Hospital, Jyväskylä, Finland.
    Subchondral bone reaction associated with chondral defect and attempted cartilage repair in goats.2004In: Calcified Tissue International, ISSN 0171-967X, E-ISSN 1432-0827, Vol. 74, no 1, p. 107-114, article id 14564432Article in journal (Refereed)
    Abstract [en]

    Repair of cartilage damage with autologous chondrocyte transplantation (ACT) has become popular in clinical use during the past few years. Although clinical results have mostly been successful, several unanswered questions remain regarding the biological mechanism of the repair process. The aim of this study was to develop a goat model for ACT. The repair was not successful due to the graft delamination, but we characterize the subchondral changes seen after the procedure. A chondral lesion was created in 14 goat knees, operated on 1 month later with ACT, and covered with periosteum or a bioabsorbable poly-L/D-lactide scaffold. After 3 months, only two of the five lesions repaired with ACT showed partly hyaline-like repair tissue, and all lesions (n = 4) with the scaffold failed. Even though the lesions did not extend through the calcified cartilage, the bone volume and collagen organization of bone structure were decreased when assessed by quantitative polarized light microscopy. There was a significant loss of bone matrix and distortion of the trabecular structure of subchondral bone, which extended several millimeters into the bone. The subchondral bone demonstrated strong hyaluronan staining in the bone marrow and cartilaginous areas with signs of endochondral ossification, suggesting structural remodeling of the bone. The goat model used here proved not to be an optimal model for ACT. The changes in subchondral bone may alter the biomechanical properties of the subchondral plate and thus the long-term survival of the repair tissue after ACT.

  • 42.
    Wallin, Olof
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Söderberg, Johan
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Van Guelpen, Bethany
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
    Brulin, Christine
    Umeå University, Faculty of Medicine, Department of Nursing.
    Grankvist, Kjell
    Umeå University, Faculty of Medicine, Department of Medical Biosciences, Clinical chemistry.
    Patient-centred care - preanalytical factors demand attention: a questionnaire study of venous blood sampling and specimen handling2007In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 67, no 8, p. 836-847Article in journal (Refereed)
    Abstract [en]

    Objective. Most mistakes in laboratory medicine are the result of human error occurring before the blood sample reaches the laboratory. This survey of preanalytical procedures was designed to identify sources of error and potential targets for quality improvement strategies.

    Material and methods. The staff in a highly specialized surgical ward at a university hospital completed a questionnaire addressing the collection and handling of venous blood samples in plastic vacuum test‐tubes for general clinical chemistry testing.

    Results. The results suggest that venous blood sampling instructions are not always followed. When uncertain about how a sample should be collected, the majority of respondents rely on potentially poor sources of information, such as out‐of‐date printed instructions or the advice of a colleague, rather than consult up‐to‐date electronic instructions. Furthermore, they do not always report errors and the referrals are not always handled according to sampling instructions. The respondents were highly motivated, however, and had a strong interest in receiving further education in, and assuming increased responsibility for, venous blood sampling procedures in the ward.

    Conclusions. We believe that the introduction of standardized routines and regular staff training, combined with an exchange of the existing paper‐based referral management system with an electronic system for managing referrals, could increase safety in the preanalytical process, with positive effects on patient safety. Given the importance of venous blood samples in patient care, a more extensive study covering other hospital wards and primary health‐care centres is needed.

    Read More: http://informahealthcare.com/doi/abs/10.1080/00365510701370675

  • 43. Zhang, Tianmu
    et al.
    Shi, Changsheng
    Zhao, Chenyang
    Wu, Zhongbin
    Sun, Ning
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Chen, Jiangshan
    Xie, Zhiyuan
    Ma, Dongge
    High efficiency phosphorescent white organic light-emitting diodes with low efficiency roll-off achieved by strategic exciton management based on simple ultrathin emitting layer structures2017In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 5, no 48, p. 12833-12838Article in journal (Refereed)
    Abstract [en]

    White organic light-emitting diodes (WOLEDs) with ultrathin emitting layer (UEML) structures have vast potential in applications due to highly simplified processing. However, the efficiency and efficiency roll-off at high luminance require further improvement. In this paper, we successfully fabricated high efficiency and low roll-off phosphorescent WOLEDs by strategically controlling the location of red, green and blue UEMLs. The probability of exciton recombination was significantly enhanced, along with greatly suppressed exciton annihilation. The resulting WOLEDs exhibited a maximum external quantum efficiency (EQE) of 20.3%, a current efficiency (CE) of 44.2 cd A(-1), and a power efficiency (PE) of 39.0 lm W-1, and remained as high as 18.8%, 41.9 cd A(-1), and 28.6 lm W-1 at a luminance of 5000 cd m(-2), respectively. Additionally, the devices showed superior warm white emission with a small variation in the Commission Internationale de l'Eclairage (CIE), from (0.47, 0.43) to (0.43, 0.44) in the luminance range of 1000 cd m(-2) to 30000 cd m(-2), and the color rendering index (CRI) was as high as 80. This should be among the best results reported so far for WOLEDs based on UEML structures, indicating the great potential of high-performance WOLEDs fabricated using a very simple technology.

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