Umeå universitets logga

umu.sePublikationer
Ändra sökning
Avgränsa sökresultatet
12 1 - 50 av 65
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Abiodun Daramola, Olamide
    et al.
    Centre for Chemico- and Biomedicinal Research (CCBR), Department of Chemistry, Faculty of Science, Rhodes University, Grahamstown, South Africa; Department of Chemical and Physical Sciences, Faculty of Natural Science, Walter Sisulu University, Private Bag XI, Mthatha, South Africa.
    Bazibuhe Safari, Justin
    Centre for Chemico- and Biomedicinal Research (CCBR), Department of Chemistry, Faculty of Science, Rhodes University, Grahamstown, South Africa; Department of Pharmacy, Faculty of Pharmaceutical Sciences and Public Health, Official University of Bukavu, Bukavu, Democratic Republic Congo.
    Adeniyi, Kayode Omotayo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Siwe-Noundou, Xavier
    Department of Pharmaceutical Sciences, School of Pharmacy, Sefako Makgatho Health Sciences University, Gauteng, Pretoria, South Africa.
    Margaret Kirkpatrick Dingle, Laura
    Biomedical Biotechnology Research Unit (BioBRU), Department of Biochemistry and Microbiology, Faculty of Science, Rhodes University, Grahamstown, South Africa.
    Lesley Edkins, Adrienne
    Biomedical Biotechnology Research Unit (BioBRU), Department of Biochemistry and Microbiology, Faculty of Science, Rhodes University, Grahamstown, South Africa.
    Foster Tseki, Potlaki
    Department of Chemical and Physical Sciences, Faculty of Natural Science, Walter Sisulu University, Private Bag XI, Mthatha, South Africa.
    Werner Maçedo Krause, Rui
    Centre for Chemico- and Biomedicinal Research (CCBR), Department of Chemistry, Faculty of Science, Rhodes University, Grahamstown, South Africa.
    Biocompatible liposome and chitosan-coated CdTe/CdSe/ZnSe multi-core-multi-shell fluorescent nanoprobe for biomedical applications2024Ingår i: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 454, artikel-id 115714Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cadmium telluride (CdTe) semiconductor quantum dots (QDs) are brightly luminescent nanocrystals that have emerged as a new class of fluorescent probes for in vivo bioimaging and theranostic applications. CdTe QDs toxicity to normal human cells is minimized by coating with a less toxic ZnS and ZnSe shell forming a core–shell nanostructure. However, coating with ZnS or ZnSe shell is insufficient to prevent the leaching of toxic Cd metal ions. To further minimize toxicity, thiol dual capped CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots were coated with nanoliposome or liposome vesicles (CdTe/CdSe/ZnSe@liposome) and chitosan nanoparticles (CdTe/CdSe/ZnSe@ChitNPs) and their biocompatibility on HeLa and Vero cells were investigated. Different spectroscopic and microscopic techniques were used to elucidate nanocomposites' optical, morphological, and physicochemical properties. The coating of CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots were conducted at different formulations (F1, F2 and F3) and results from the fluorescence studies show that F3 demonstrated the best interaction for both liposome and ChitNPs composite. Exposure to 12 h UV illumination studies also reveals that CdTe/CdSe/ZnSe@liposome shows an enhancement in fluorescence compared to CdTe/CdSe/ZnSe@ChitNPs. The cytotoxicity of the formulations towards HeLa and Vero cells also depicted minimal toxicity compared to CdTe/CdSe/ZnSe QDs that shows much higher toxicity (IC50 = 0.09381 mg/ml). It was further observed that liposome coated multi-core-multi-shell QDs@F2 demonstrated lower toxicity (IC50 = 0.4364 mg/ml) compared to ChitNPs coated multi-core-multi-shell QDs@F2 (IC50 = 0.1618 mg/ml). Results from the florescence imaging studies reveal that CdTe/CdSe/ZnSe-multi-core-multi-shell QDs liposomes and ChitNPs composite retained most of their fluorescence and properties and could easily be tracked in cells and visualized around the nucleus. This indicates the successful internalization of the QDs in the cytosol. Therefore, these results shows that coating CdTe multi-core-mutli-shell QDs with liposomes and ChitNPs produce better biocompatibility compared to uncoated multi-core–shell QDs. However, liposome coated CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots show better optical properties, photostability and biocompatibility compared to CdTe/CdSe/ZnSe multi-core-multi-shell quantum dots with ChitNPs coating. These particles therefore show good promise in cell-labelling and drug delivery studies.

    Ladda ner fulltext (pdf)
    fulltext
  • 2.
    Addi, Simon
    et al.
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Hedayati-Khams, Arjang
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Poya, Amin
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Sjögren, Göran
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Interface gap size of manually and CAD/CAM-manufactured ceramic inlays/onlays in vitro.2002Ingår i: Journal of Dentistry, ISSN 0300-5712, E-ISSN 1879-176X, Vol. 30, nr 1, s. 53-58Artikel i tidskrift (Refereegranskat)
    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.

  • 3. Azinas, S.
    et al.
    Bano, F.
    Torca, I.
    Bamford, D. H.
    Schwartz, G. A.
    Esnaola, J.
    Oksanen, H. M.
    Richter, R. P.
    Abrescia, N. G.
    Membrane-containing virus particles exhibit the mechanics of a composite material for genome protection2018Ingår i: Nanoscale, Vol. 10, nr 16, s. 7769-7779Artikel i tidskrift (Refereegranskat)
  • 4.
    Bano, Fouzia
    et al.
    CIC biomaGUNE, Donostia-San Sebastian, Spain.
    Banerji, Suneale
    Howarth, Mark
    Jackson, David G.
    Richter, Ralf P.
    A single molecule assay to probe monovalent and multivalent bonds between hyaluronan and its key leukocyte receptor CD44 under force2016Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 6, artikel-id 34176Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Glycosaminoglycans (GAGs), a category of linear, anionic polysaccharides, are ubiquitous in the extracellular space, and important extrinsic regulators of cell function. Despite the recognized significance of mechanical stimuli in cellular communication, however, only few single molecule methods are currently available to study how monovalent and multivalent GAG·protein bonds respond to directed mechanical forces. Here, we have devised such a method, by combining purpose-designed surfaces that afford immobilization of GAGs and receptors at controlled nanoscale organizations with single molecule force spectroscopy (SMFS). We apply the method to study the interaction of the GAG polymer hyaluronan (HA) with CD44, its receptor in vascular endothelium. Individual bonds between HA and CD44 are remarkably resistant to rupture under force in comparison to their low binding affinity. Multiple bonds along a single HA chain rupture sequentially and independently under load. We also demonstrate how strong non-covalent bonds, which are versatile for controlled protein and GAG immobilization, can be effectively used as molecular anchors in SMFS. We thus establish a versatile method for analyzing the nanomechanics of GAG·protein interactions at the level of single GAG chains, which provides new molecular-level insight into the role of mechanical forces in the assembly and function of GAG-rich extracellular matrices.

    Ladda ner fulltext (pdf)
    fulltext
  • 5.
    Bano, Fouzia
    et al.
    CIC biomaGUNE, Donostia - San Sebastian, Spain.
    Carril, Mónica
    Di Gianvincenzo, Paolo
    Richter, Ralf P.
    Interaction of hyaluronan with cationic nanoparticles2015Ingår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, nr 30, s. 8411-8420Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The polysaccharide hyaluronan (HA) is a main component of peri- and extracellular matrix, and an attractive molecule for materials design in tissue engineering and nanomedicine. Here, we study the morphology of complexes that form upon interaction of nanometer-sized amine-coated gold particles with this anionic, linear, and regular biopolymer in solution and grafted to a surface. We find that cationic nanoparticles (NPs) have profound effects on HA morphology on the molecular and supramolecular scale. Quartz crystal microbalance (QCM-D) shows that depending on their relative abundance, cationic NPs promote either strong compaction or swelling of films of surface-grafted HA polymers (HA brushes). Transmission electron and atomic force microscopy reveal that the NPs do also give rise to complexes of distinct morphologies–compact nanoscopic spheres and extended microscopic fibers–upon interaction with HA polymers in solution. In particular, stable and hydrated spherical complexes of single HA polymers with NPs can be prepared when balancing the ionizable groups on HA and NPs. The observed self-assembly phenomena could be useful for the design of drug delivery vehicles and a better understanding of the reorganization of HA-rich synthetic or biological matrices.

  • 6.
    Bano, Fouzia
    et al.
    University of Liège, Department of Chemistry, Belgium.
    Sluysmans, D.
    Wislez, A.
    Duwez, A. -S
    Unraveling the complexity of the interactions of DNA nucleotides with gold by single molecule force spectroscopy2015Ingår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, nr 46, s. 19528-19533Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Addressing the effect of different environmental factors on the adsorption of DNA to solid supports is critical for the development of robust miniaturized devices for applications ranging from biosensors to next generation molecular technology. Most of the time, thiol-based chemistry is used to anchor DNA on gold – a substrate commonly used in nanotechnology – and little is known about the direct interaction between DNA and gold. So far there have been no systematic studies on the direct adsorption behavior of the deoxyribonucleotides (i.e., a nitrogenous base, a deoxyribose sugar, and a phosphate group) and on the factors that govern the DNA–gold bond strength. Here, using single molecule force spectroscopy, we investigated the interaction of the four individual nucleotides, adenine, guanine, cytosine, and thymine, with gold. Experiments were performed in three salinity conditions and two surface dwell times to reveal the factors that influence nucleotide–Au bond strength. Force data show that, at physiological ionic strength, adenine–Au interactions are stronger, asymmetrical and independent of surface dwell time as compared to cytosine–Au and guanine–Au interactions. We suggest that in these conditions only adenine is able to chemisorb on gold. A decrease of the ionic strength significantly increases the bond strength for all nucleotides. We show that moderate ionic strength along with longer surface dwell period suggest weak chemisorption also for cytosine and guanine.

  • 7.
    Bano, Fouzia
    et al.
    School of Biomedical Sciences, Faculty of Biological Sciences, School of Physics and Astronomy, Faculty of Mathematics and Physical Sciences, and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom; CIC biomaGUNE, Biosurfaces Laboratory, Donostia-San Sebastian, Spain.
    Tammi, M. I.
    Kang, D. W.
    Harris, E. N.
    Richter, R. P.
    Single-molecule unbinding forces between the polysaccharide hyaluronan and its binding proteins2018Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 114, nr 12, s. 2910-2922Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The extracellular polysaccharide hyaluronan (HA) is ubiquitous in all vertebrate tissues, where its various functions are encoded in the supramolecular complexes and matrices that it forms with HA-binding proteins (hyaladherins). In tissues, these supramolecular architectures are frequently subjected to mechanical stress, yet how this affects the intermolecular bonding is largely unknown. Here, we used a recently developed single-molecule force spectroscopy platform to analyze and compare the mechanical strength of bonds between HA and a panel of hyaladherins from the Link module superfamily, namely the complex of the proteoglycan aggrecan and cartilage link protein, the proteoglycan versican, the inflammation-associated protein TSG-6, the HA receptor for endocytosis (stabilin-2/HARE), and the HA receptor CD44. We find that the resistance to tensile stress for these hyaladherins correlates with the size of the HA-binding domain. The lowest mean rupture forces are observed for members of the type A subgroup (i.e., with the shortest HA-binding domains; TSG-6 and HARE). In contrast, the mechanical stability of the bond formed by aggrecan in complex with cartilage link protein (two members of the type C subgroup, i.e., with the longest HA-binding domains) and HA is equal or even superior to the high affinity streptavidin⋅biotin bond. Implications for the molecular mechanism of unbinding of HA⋅hyaladherin bonds under force are discussed, which underpin the mechanical properties of HA⋅hyaladherin complexes and HA-rich extracellular matrices.

    Ladda ner fulltext (pdf)
    fulltext
  • 8. 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 signals2011Ingår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 32, nr 7, s. 1778-1786Artikel i tidskrift (Refereegranskat)
    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.

  • 9.
    Chen, Zhixuan
    et al.
    School of Medicine, Southeast University, Nanjing, China; Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing, China.
    Zhang, Wei
    School of Medicine, Southeast University, Nanjing, China; Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing, China; Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing, China; China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, China.
    Wang, Mingyue
    School of Medicine, Southeast University, Nanjing, China; Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing, China.
    Backman, Ludvig J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för fysioterapi.
    Chen, Jialin
    School of Medicine, Southeast University, Nanjing, China; Center for Stem Cell and Regenerative Medicine, Southeast University, Nanjing, China; Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing, China; China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, China.
    Effects of Zinc, Magnesium, and Iron Ions on Bone Tissue Engineering2022Ingår i: ACS Biomaterials Science & Engineering, E-ISSN 2373-9878, Vol. 8, nr 6, s. 2321-2335Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Large-sized bone defects are a great challenge in clinics and considerably impair the quality of patients' daily life. Tissue engineering strategies using cells, scaffolds, and bioactive molecules to regulate the microenvironment in bone regeneration is a promising approach. Zinc, magnesium, and iron ions are natural elements in bone tissue and participate in many physiological processes of bone metabolism and therefore have great potential for bone tissue engineering and regeneration. In this review, we performed a systematic analysis on the effects of zinc, magnesium, and iron ions in bone tissue engineering. We focus on the role of these ions in properties of scaffolds (mechanical strength, degradation, osteogenesis, antibacterial properties, etc.). We hope that our summary of the current research achievements and our notifications of potential strategies to improve the effects of zinc, magnesium, and iron ions in scaffolds for bone repair and regeneration will find new inspiration and breakthroughs to inspire future research.

  • 10.
    Chi, Jiayu
    et al.
    School of Medicine, Southeast University, Nanjing, China.
    Wang, Mingyue
    School of Medicine, Southeast University, Nanjing, China.
    Chen, Jialin
    School of Medicine, Southeast University, Nanjing, China; Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing, China; China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, China.
    Hu, Lizhi
    School of Medicine, Southeast University, Nanjing, China.
    Chen, Zhixuan
    School of Medicine, Southeast University, Nanjing, China.
    Backman, Ludvig J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för fysioterapi.
    Zhang, Wei
    School of Medicine, Southeast University, Nanjing, China; Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing, China; China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, China.
    Topographic Orientation of Scaffolds for Tissue Regeneration: Recent Advances in Biomaterial Design and Applications2022Ingår i: Biomimetics, E-ISSN 2313-7673, Vol. 7, nr 3, artikel-id 131Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Tissue engineering to develop alternatives for the maintenance, restoration, or enhancement of injured tissues and organs is gaining more and more attention. In tissue engineering, the scaffold used is one of the most critical elements. Its characteristics are expected to mimic the native extracellular matrix and its unique topographical structures. Recently, the topographies of scaffolds have received increasing attention, not least because different topographies, such as aligned and random, have different repair effects on various tissues. In this review, we have focused on various technologies (electrospinning, directional freeze-drying, magnetic freeze-casting, etching, and 3-D printing) to fabricate scaffolds with different topographic orientations, as well as discussed the physicochemical (mechanical properties, porosity, hydrophilicity, and degradation) and biological properties (morphology, distribution, adhesion, proliferation, and migration) of different topographies. Subsequently, we have compiled the effect of scaffold orientation on the regeneration of vessels, skin, neural tissue, bone, articular cartilage, ligaments, tendons, cardiac tissue, corneas, skeletal muscle, and smooth muscle. The compiled information in this review will facilitate the future development of optimal topographical scaffolds for the regeneration of certain tissues. In the majority of tissues, aligned scaffolds are more suitable than random scaffolds for tissue repair and regeneration. The underlying mechanism explaining the various effects of aligned and random orientation might be the differences in “contact guidance”, which stimulate certain biological responses in cells.

    Ladda ner fulltext (pdf)
    fulltext
  • 11. Ekstrand-Hammarström, Barbro
    et al.
    Hong, Jaan
    Davoodpour, Padideh
    Sandholm, Kerstin
    Ekdahl, Kristina N.
    Bucht, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Lungmedicin.
    Nilsson, Bo
    TiO2 nanoparticles tested in a novel screening whole human blood model of toxicity trigger adverse activation of the kallikrein system at low concentrations2015Ingår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 51, s. 58-68Artikel i tidskrift (Refereegranskat)
    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. 

  • 12.
    Feng, Xianhui
    et al.
    Faculty of Infrastructure Engineering Dalian University of Technology Dalian China.
    Kou, Wen
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Tandteknikerutbildning.
    Liu, Hongyuan
    College of Science and Engineering University of Tasmania Hobart Australia.
    Gong, Bin
    Faculty of Infrastructure Engineering Dalian University of Technology Dalian China;Department of Civil and Environmental Engineering Brunel University London London UK.
    Tang, Chun'an
    Faculty of Infrastructure Engineering Dalian University of Technology Dalian China.
    Study on fracture behavior of molars based on three‐dimensional high‐precision computerized tomography scanning and numerical simulation2022Ingår i: International Journal for Numerical Methods in Biomedical Engineering, ISSN 2040-7939, E-ISSN 2040-7947, Vol. 38, nr 3, artikel-id e3561Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of three-dimensional (3D) numerical simulations are conducted to investigate the gradual failure process of molars in this study. The real morphology and internal mesoscopic structure of a whole tooth are implemented into the numerical simulations through computerized tomography scanning, digital image processing, and 3D matrix mapping. The failure process of the whole tooth subject to compressions including crack initiation, crack propagation, and final failure pattern is reproduced using 3D realistic failure process analysis (RFPA3D) method. It is concluded that a series of microcracks are gradually initiated, nucleated, and subsequently interconnect to form macroscopic cracks when the teeth are under over-compressions. The propagation of the macroscopic cracks results in the formation of fracture surfaces and penetrating cracks, which are essential signs and manifestations of the tooth failure. Moreover, the simulations reveal that, the material heterogeneity is a critical factor that affects the mechanical properties and fracture modes of the teeth, which vary from crown fractures to crown-root fractures and root fractures depending on different homogeneity indices.

  • 13. Frost, Rickard
    et al.
    Débarre, Delphine
    Jana, Saikat
    Bano, Fouzia
    School of Biomedical Sciences, Faculty ofBiological Sciences, School of Physics and Astronomy, Faculty ofEngineering and Physical Sciences, Astbury Centre of StructuralMolecular Biology, and Bragg Centre for Materials Research,University of Leeds, Leeds LS2 9JT, United Kingdom.
    Schünemann, Jürgen
    Görlich, Dirk
    Richter, Ralf P.
    A method to quantify molecular diffusion within thin solvated polymer films: A case study on films of natively unfolded nucleoporins2020Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 14, nr 8, s. 9938-9952Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a method to probe molecular and nanoparticle diffusion within thin, solvated polymer coatings. The device exploits the confinement with well-defined geometry that forms at the interface between a planar and a hemispherical surface (of which at least one is coated with polymers) in close contact and uses this confinement to analyze diffusion processes without interference of exchange with and diffusion in the bulk solution. With this method, which we call plane–sphere confinement microscopy (PSCM), information regarding the partitioning of molecules between the polymer coating and the bulk liquid is also obtained. Thanks to the shape of the confined geometry, diffusion and partitioning can be mapped as a function of compression and concentration of the coating in a single experiment. The method is versatile and can be integrated with conventional optical microscopes; thus it should find widespread use in the many application areas exploiting functional polymer coatings. We demonstrate the use of PSCM using brushes of natively unfolded nucleoporin domains rich in phenylalanine–glycine repeats (FG domains). A meshwork of FG domains is known to be responsible for the selective transport of nuclear transport receptors (NTRs) and their macromolecular cargos across the nuclear envelope that separates the cytosol and the nucleus of living cells. We find that the selectivity of NTR uptake by FG domain films depends sensitively on FG domain concentration and that the interaction of NTRs with FG domains obstructs NTR movement only moderately. These observations contribute important information to better understand the mechanisms of selective NTR transport.

    Ladda ner fulltext (pdf)
    fulltext
  • 14. Georgiou, Melanie
    et al.
    Golding, Jon P.
    Loughlin, Alison J.
    Kingham, Paul J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi.
    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 nerve2015Ingår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 37, s. 242-251Artikel i tidskrift (Refereegranskat)
    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. 

  • 15. Giubertoni, Giulia
    et al.
    Ortíz, Alberto Pérez de Alba
    Bano, Fouzia
    School of Biomedical Sciences, Faculty of Biological Sciences, School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, Astbury Centre of Structural Molecular Biology, and Bragg Centre for Materials Research, University of Leeds, Leeds, UK.
    Zhang, Xing
    Linhardt, Robert J.
    Green, Dixy E.
    DeAngelis, Paul L.
    Koenderink, Gijsje H.
    Richter, Ralf P.
    Ensing, Bernd
    Bakker, Huib J.
    Strong reduction of the chain rigidity of hyaluronan by selective binding of Ca2+ ions2021Ingår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 54, nr 3, s. 1137-1146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The biological functions of natural polyelectrolytes are strongly influenced by the presence of ions, which bind to the polymer chains and thereby modify their properties. Although the biological impact of such modifications is well recognized, a detailed molecular picture of the binding process and of the mechanisms that drive the subsequent structural changes in the polymer is lacking. Here, we study the molecular mechanism of the condensation of calcium, a divalent cation, on hyaluronan, a ubiquitous polymer in human tissues. By combining two-dimensional infrared spectroscopy experiments with molecular dynamics simulations, we find that calcium specifically binds to hyaluronan at millimolar concentrations. Because of its large size and charge, the calcium cation can bind simultaneously to the negatively charged carboxylate group and the amide group of adjacent saccharide units. Molecular dynamics simulations and single-chain force spectroscopy measurements provide evidence that the binding of the calcium ions weakens the intramolecular hydrogen-bond network of hyaluronan, increasing the flexibility of the polymer chain. We also observe that the binding of calcium to hyaluronan saturates at a maximum binding fraction of ∼10–15 mol %. This saturation indicates that the binding of Ca2+ strongly reduces the probability of subsequent binding of Ca2+ at neighboring binding sites, possibly as a result of enhanced conformational fluctuations and/or electrostatic repulsion effects. Our findings provide a detailed molecular picture of ion condensation and reveal the severe effect of a few, selective and localized electrostatic interactions on the rigidity of a polyelectrolyte chain.

    Ladda ner fulltext (pdf)
    fulltext
  • 16.
    Hou, Jiapeng
    et al.
    Section of Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
    Wang, Lutian
    Section of Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
    Alm, Martin
    Biomodics ApS, Rødovre, Denmark.
    Thomsen, Peter
    Biomodics ApS, Rødovre, Denmark.
    Monsen, Tor
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Ramstedt, Madeleine
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Burmølle, Mette
    Section of Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
    Enhanced Antibiotic Tolerance of an In Vitro Multispecies Uropathogen Biofilm Model, Useful for Studies of Catheter-Associated Urinary Tract Infections2022Ingår i: Microorganisms, E-ISSN 2076-2607, Vol. 10, nr 6, artikel-id 1207Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catheter-associated urinary tract infections (CAUTI) are a common clinical concern as they can lead to severe, persistent infections or bacteremia in long-term catheterized patients. This type of CAUTI is difficult to eradicate, as they are caused by multispecies biofilms that may have reduced susceptibility to antibiotics. Many new strategies to tackle CAUTI have been proposed in the past decade, including antibiotic combination treatments, surface modification and probiotic usage. However, those strategies were mainly assessed on mono- or dual-species biofilms that hardly represent the long-term CAUTI cases where, normally, 2–4 or even more species can be involved. We developed a four-species in vitro biofilm model on catheters involving clinical strains of Escherichia coli, Pseudomonas aeruginosa, Klebsiella oxytoca and Proteus mirabilis isolated from indwelling catheters. Interspecies interactions and responses to antibiotics were quantitatively assessed. Collaborative as well as competitive interactions were found among members in our model biofilm and those interactions affected the individual species&rsquo; abundances upon exposure to antibiotics as mono-, dual- or multispecies biofilms. Our study shows complex interactions between species during the assessment of CAUTI control strategies for biofilms and highlights the necessity of evaluating treatment and control regimes in a multispecies setting.

    Ladda ner fulltext (pdf)
    fulltext
  • 17.
    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.2012Ingår i: Journal of Functional Biomaterials, E-ISSN 2079-4983, Vol. 3, nr 3, s. 544-555, artikel-id 23807905Artikel i tidskrift (Refereegranskat)
    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.

  • 18.
    Håff, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    Löf, Hanna
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    Gunne, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Protetik.
    Sjögren, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    A retrospective evaluation of zirconia-fixed partial dentures in general practices: an up to 13-year study2015Ingår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 31, nr 2, s. 162-170Artikel i tidskrift (Refereegranskat)
    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.

  • 19. Johansson, Kristin
    et al.
    Christophliemk, Hanna
    Johansson, Caisa
    Jönsson, Leif
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Järnström, Lars
    The effects of coating structure and water-holding capacity on the oxygen-scavenging ability of enzymes embedded in the coating layer2013Ingår i: TAPPI Journal, ISSN 0734-1415, Vol. 12, nr 6, s. 43-52Artikel i tidskrift (Refereegranskat)
    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.

  • 20.
    Kou, Wen
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    On dental ceramics and their fracture: a laboratory and numerical study2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

    Ladda ner fulltext (pdf)
    FULLTEXT01
  • 21.
    Kou, Wen
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap. Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    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 universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    Numerical modeling of the fracture process in a three-unit all-ceramic fixed partial denture2007Ingår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 23, nr 8, s. 1042-1049Artikel i tidskrift (Refereegranskat)
    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.

  • 22.
    Kou, Wen
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    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 universitet, Medicinska fakulteten, Institutionen för odontologi.
    Numerical simulation of the fracture process in ceramic FPD frameworks caused by oblique loading2015Ingår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 50, s. 206-214Artikel i tidskrift (Refereegranskat)
    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.

  • 23.
    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 universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Nanostructured coatings for biomedical applications by ultra short pulsed laser deposition2015Ingår i: Comprehensive guide for nanocoatings technology: Volume 3, Properties and development / [ed] Mahmoud Aliofkhadzraei, Nova Science Publishers, Inc., 2015, 3, s. 309-323Kapitel i bok, del av antologi (Refereegranskat)
    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.

  • 24.
    Lindholm-Sethson, Britta
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ardlin, Berit
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    Effects of pH and fluoride concentration on the corrosion of titanium2008Ingår i: Journal of Biomedical Materials Research Part A, ISSN 1549-3296, Vol. 86A, nr 1, s. 149-159Artikel i tidskrift (Refereegranskat)
    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.

  • 25.
    Magnusson, Catarina
    et al.
    Department of Orthodontics, Institute of Odontology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Uribe, Pamela
    Department of Orthodontics, Institute of Odontology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Jugdaohsingh, Ravin
    Biomineral Research Group, Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
    Powell, Jonathan J.
    Biomineral Research Group, Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
    Johansson, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Ransjö, Maria
    Department of Orthodontics, Institute of Odontology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Inhibitory effects of orthosilicic acid on osteoclastogenesis in RANKL-stimulated RAW264.7 cells2021Ingår i: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 109, nr 10, s. 1967-1978Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Numerous studies have reported on the positive effects of silicon (Si) on bone metabolism, particularly on the stimulatory effects of Si on osteoblast cells and on bone formation. Inhibitory effects of Si on osteoclast formation and bone resorption have also been demonstrated in vitro and are suggested to be mediated indirectly via stromal and osteoblast cells. Direct effects of Si on osteoclasts have been less studied and mostly using soluble Si, but no characterisation of the Si treatment solutions are provided. The aims of the present study were to (a) further investigate the direct inhibitory effects of Si on osteoclastogenesis in RANKL-stimulated RAW264.7 cells, (b) determine at what stage during osteoclastogenesis Si acts upon, and (c) determine if these effects can be attributed to the biologically relevant soluble orthosilicic acid specie. Our results demonstrate that silicon, at 50 μg/ml (or 1.8 mM), does not affect cell viability but directly inhibits the formation of TRAP+ multinucleated cells and the expression of osteoclast phenotypic genes in RAW264.7 cells. The inhibitory effect of Si was clearly associated with the early stages (first 24 hr) of osteoclastogenesis. Moreover, these effects can be attributed to the soluble orthosilicic acid specie.

    Ladda ner fulltext (pdf)
    fulltext
  • 26.
    Melo Filho, Alberto
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Drotz, Stina
    Tsai, Chia-Jung
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Ragnvaldsson, Daniel
    Larsson, Christer
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Heat-killing of Legionella in biological sludge from a paper and pulp mill water treatment plant2015Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 30, nr 1, s. 121-125Artikel i tidskrift (Refereegranskat)
    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.

  • 27. Mladenović, Živko
    et al.
    Johansson, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Willman, Britta
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Shahabi, Kaveh
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Björn, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Ransjö, Maria
    Soluble silica inhibits osteoclast formation and bone resorption in vitro2014Ingår i: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 10, nr 1, s. 406-418Artikel i tidskrift (Refereegranskat)
    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.

  • 28.
    Mo, Qingyun
    et al.
    School of Medicine, Southeast University, Nanjing, China.
    Zhang, Wei
    School of Medicine, Southeast University, Nanjing, China; Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing, China; China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, China.
    Zhu, Aijing
    School of Medicine, Southeast University, Nanjing, China.
    Backman, Ludvig J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Avdelningen för fysioterapi.
    Chen, Jialin
    School of Medicine, Southeast University, Nanjing, China; Jiangsu Key Laboratory for Biomaterials and Devices, Southeast University, Nanjing, China; China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, China.
    Regulation of osteogenic differentiation by the pro-inflammatory cytokines IL-1β and TNF-α: current conclusions and controversies2022Ingår i: Human Cell, ISSN 0914-7470, Vol. 35, s. 957-971Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Treatment of complex bone fracture diseases is still a complicated problem that is urged to be solved in orthopedics. In bone tissue engineering, the use of mesenchymal stromal/stem cells (MSCs) for tissue repair brings hope to the medical field of bone diseases. MSCs can differentiate into osteoblasts and promote bone regeneration. An increasing number of studies show that the inflammatory microenvironment affects the osteogenic differentiation of MSCs. It is shown that TNF-α and IL-1β play different roles in the osteogenic differentiation of MSCs via different signal pathways. The main factors that affect the role of TNF-α and IL-1β in osteogenic differentiation of MSCs include concentration and the source of stem cells (different species and different tissues). This review in-depth analyzes the roles of pro-inflammatory cytokines in the osteogenic differentiation of MSCs and reveals some current controversies to provide a reference of comprehensively understanding.

  • 29.
    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 universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. 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 study2014Ingår i: Journal of Material Chemistry B, ISSN 2050-750X, Vol. 2, nr 10, s. 1307-1316Artikel i tidskrift (Refereegranskat)
    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.

  • 30.
    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.2009Ingår i: Journal of materials science. Materials in medicine, ISSN 0957-4530, E-ISSN 1573-4838, Vol. 20, nr 11, s. 2337-2347, artikel-id 19507005Artikel i tidskrift (Refereegranskat)
    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.

  • 31.
    Mårell, Lena
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    A multidisciplinary study of patients with signs or symptoms attributed to dental restorative materials2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    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.

    Ladda ner fulltext (pdf)
    fulltext
    Ladda ner (pdf)
    omslag
    Ladda ner (pdf)
    spikblad
  • 32.
    Mårell, Lena
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Bergdahl, Jan
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Department of Clinical Dentistry, University of Tromsø, Tromsø, Norway.
    Tillberg, Anders
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Public Dental Health Competence Centre for Northern Norway, Tromsø, Norway.
    Stenberg, Berndt
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Avdelningen för medicin.
    Berglund, Anders
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Psychological symptoms and self-image of patients with complaints attributed to dental restorative materials2019Ingår i: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 23, nr 6, s. 2805-2811Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 33.
    Novikova, Liudmila N.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Kolar, Mallappa K.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Kingham, Paul J.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Ullrich, Andreas
    Oberhoffner, Sven
    Renardy, Monika
    Doser, Michael
    Müller, Erhard
    Wiberg, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap.
    Novikov, Lev N.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Trimethylene carbonate-caprolactone conduit with poly-p-dioxanone microfilaments to promote regeneration after spinal cord injury2018Ingår i: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 66, s. 177-191Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 34.
    Ouasti, Sihem
    et al.
    University of Manchester.
    Kingham, Paul J
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Anatomi. 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 acid2012Ingår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 33, nr 4, s. 1120-1134Artikel i tidskrift (Refereegranskat)
    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.

  • 35.
    Persson-Sjögren, Solveig
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi.
    Sjögren, Göran
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Effects of dental materials on insulin release from isolated islets of Langerhans2002Ingår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 18, nr 1, s. 20-25Artikel i tidskrift (Refereegranskat)
    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.

  • 36.
    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.2006Ingår i: Bio-medical materials and engineering, ISSN 0959-2989, E-ISSN 1878-3619, Vol. 16, nr 4 Suppl, s. S29-S35, artikel-id 16823110Artikel i tidskrift (Refereegranskat)
    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.

  • 37.
    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.2010Ingår i: Osteoarthritis and Cartilage, ISSN 1063-4584, E-ISSN 1522-9653, Vol. 18, nr 8, s. 1077-1087, artikel-id 20472086Artikel i tidskrift (Refereegranskat)
    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.

  • 38.
    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.2008Ingår i: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 31, nr 11, s. 960-969, artikel-id 19089798Artikel i tidskrift (Refereegranskat)
    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.

  • 39.
    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.2011Ingår i: Journal of Applied Biomaterials and Biomechanics, ISSN 1722-6899, Vol. 9, nr 1, s. 47-53, artikel-id 21445828Artikel i tidskrift (Refereegranskat)
    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.

  • 40.
    Qi, Xingmei
    et al.
    The Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China.
    Wang, Han
    The Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China.
    Wang, Kezhen
    School of Life Sciences, Anhui Medical University, Anhui, Hefei, China.
    Wang, Yu
    Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden; College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China.
    Leppert, Axel
    Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden.
    Iashchishyn, Igor
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Zhong, Xueying
    School of Engineering Sciences in Chemistry, Biotechnology and Health, Department of Biomedical Engineering and Health Systems, KTH Royal Institute of Technology, Huddinge, Sweden.
    Zhou, Yizhong
    Faculty of Food Science and Technology, Suzhou Polytechnic Institute of Agriculture, Suzhou, China.
    Liu, Ruifang
    The Jiangsu Key Laboratory of Infection and Immunity, Institutes of Biology and Medical Sciences, Soochow University, Suzhou, China.
    Rising, Anna
    Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden; Department of Animal Biosciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Landreh, Michael
    Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden.
    Johansson, Jan
    Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.
    Chen, Gefei
    Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden; Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.
    Spiders use structural conversion of globular amyloidogenic domains to make strong silk fibers2024Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, artikel-id 2315409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Spider silk—an environmentally friendly protein-based material—is widely recognized for its extraordinary mechanical properties. Biomimetic spider silk-like fibers made from recombinant spider silk proteins (spidroins) currently falls short compared to natural silks in terms of mechanical performance. In this study, it is discovered that spiders use structural conversion of molecular enhancers—conserved globular 127-residue spacer domains—to make strong silk fibers. This domain lacks poly-Ala motifs but interestingly contains motifs that are similar to human amyloidogenic motifs, and that it self-assembles into amyloid-like fibrils through a non-nucleation-dependent pathway, likely to avoid the formation of cytotoxic intermediates. Incorporating this spacer domain into a recombinant chimeric spidroin facilitates self-assembly into silk-like fibers, increases fiber molecular homogeneity, and markedly enhances fiber mechanical strength. These findings highlight that spiders employ diverse strategies to produce silk with exceptional mechanical properties. The spacer domain offers a way to enhance the properties of recombinant spider silk-like fibers and other functional materials.

    Ladda ner fulltext (pdf)
    fulltext
  • 41.
    Qu, Chengjuan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (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 universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (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 coatings2016Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 9, nr 10, artikel-id 827Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 42. Raina, Deepak Bushan
    et al.
    Larsson, David
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap. Lund University, Faculty of Medicine, Department of Clinical Sciences Lund, Orthopedics, Lund, Sweden.
    Sezgin, Erdem Aras
    Isaksson, Hanna
    Tägil, Magnus
    Lidgren, Lars
    Biomodulation of an implant for enhanced bone-implant anchorage2019Ingår i: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 96, s. 619-630Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aseptic loosening of implants is the major cause for revision surgery. By modulating the bone-implant interface, early bone-implant anchorage could be improved. Implant surface manipulation by the addition of osteopromotive molecules locally and systemically to promote implant integration has been described with limited success. This study describes a novel approach by making the implant capable of biologically modulating its surroundings. It was hypothesized that the early implant fixation would improve by filling the interior of the implant with a carrier providing spatio-temporal release of bone active drugs with known osteogenic effect. The implant consisted of a threaded polyether ether ketone (PEEK) hollow chamber with holes at the bottom. The implant was filled with a calcium sulphate (CaS)/hydroxyapatite (HA) carrier, delivering two bone active molecules; zoledronic acid (ZA) and bone morphogenic protein-2 (BMP-2). At first, a rat abdominal muscle pouch model indicated a sustained in-vivo release of both I-125-rhBMP-2 (57%) and C-14-ZA (22%) from the CaS/HA carrier over a period of 4-weeks. The biomodulated implant was then inserted in the proximal tibia in rats with the following experimental groups: G1) Empty implant, G2) Implant + CaS/HA, G3) Implant + CaS/HA + ZA and G4) Implant + CaS/HA + ZA + rhBMP-2. Significantly higher bone volume (BV) was seen around the implant in groups G3 (3.3 +/- 0.7 mm(3)) and G4 (3.1 +/- 0.7 mm(3)) compared to the control (1.3 +/- 0.4 mm(3)) using micro-computed tomography and qualitative histology. Group G3, also exhibited significantly higher pull-out force and absorbed energy when compared to the control group G1. These findings indicate that a low dose of ZA alone, released in a controlled manner from within a fenestrated implant is enough to improve implant anchorage without the need of adding rhBMP-2. This simple method of using a fenestrated implant containing a ceramic carrier releasing bone active molecules improved bone anchorage and could clinically reduce prosthetic failure. Statement of Significance Aseptic loosening remains as a major cause for implant revisions and early reaction of surrounding bone to the prosthesis is important for longevity. A novel approach to enhance early bone-implant anchorage is presented. The implant is filled with a carrier providing controlled release of bone active molecules. In an animal model, a calcium sulphate (CaS)/hydroxyapatite (HA) carrier was used to provide a spatio-temporal release of bone morphogenic protein-2 (BMP-2) and zoledronic acid (ZA). Significantly better bone-implant integration was achieved using ZA alone, thereby eliminating the need for adding BMP-2. The developed method of implant biomodulation holds potential to prevent implant loosening and is an alternative to prosthetic coatings or systemic drug treatment. Importantly, all constituents are approved for clinical use.

    Ladda ner fulltext (pdf)
    fulltext
  • 43. Raina, Deepak Bushan
    et al.
    Qayoom, Irfan
    Larsson, David
    Umeå universitet, Medicinska fakulteten. 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 delivery2019Ingår i: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 188, s. 38-49Artikel i tidskrift (Refereegranskat)
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 44.
    Ramstedt, Madeleine
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    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 Recommendations2019Ingår i: Macromolecular Bioscience, ISSN 1616-5187, E-ISSN 1616-5195, Vol. 19, nr 5, artikel-id 1800384Artikel, forskningsöversikt (Refereegranskat)
    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.

  • 45.
    Sjögren, Göran
    et al.
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Lantto, Rolf
    Granberg, Åsa
    Sundström, Bengt-Olov
    Tillberg, Anders
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Clinical examination of leucite-reinforced glass-ceramic crowns (Empress) in general practice: a retrospective study1999Ingår i: International Journal of Prosthodontics, ISSN 0893-2174, E-ISSN 1139-9791, Vol. 12, nr 2, s. 122-128Artikel i tidskrift (Refereegranskat)
    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.

  • 46.
    Sjögren, Göran
    et al.
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Lantto, Rolf
    Tillberg, Anders
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    Clinical evaluation of all-ceramic crowns (Dicor) in general practice.1999Ingår i: The Journal of prosthetic dentistry (Print), ISSN 0022-3913, E-ISSN 1097-6841, Vol. 81, nr 3, s. 277-284Artikel i tidskrift (Refereegranskat)
    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.

  • 47.
    Sjögren, Göran
    et al.
    Umeå universitet, Medicinsk fakultet, Odontologi, Odontologisk materialvetenskap.
    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.2002Ingår i: The Journal of Prosthetic Dentistry, ISSN 0022-3913, Vol. 84, nr 2, s. 229-236Artikel i tidskrift (Refereegranskat)
    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.

  • 48. 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 conduit2010Ingår i: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 93, nr 4, s. 1470-1481Artikel i tidskrift (Refereegranskat)
    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.

  • 49.
    Sundh, Anders
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi.
    Molin, Margareta
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Protetik.
    Sjögren, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    Fracture resistance of yttrium oxide partially-stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing2005Ingår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 21, nr 5, s. 476-482Artikel i tidskrift (Refereegranskat)
    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.

  • 50.
    Sundh, Anders
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    Sjögren, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för odontologi, Odontologisk materialvetenskap.
    Fracture resistance of all-ceramic zirconia bridges with differing phase stabilizers and quality of sintering2006Ingår i: Dental Materials, ISSN 0109-5641, E-ISSN 1879-0097, Vol. 22, nr 8, s. 778-784Artikel i tidskrift (Refereegranskat)
    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.

12 1 - 50 av 65
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf