| 1. |
- Muzamal, Muhammad, 1986
(författare)
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Steam Explosion of Wood
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The rising price of petroleum and environmental concerns regarding CO2 emissions has increased interest in alternative renewable resources. Biomass can be considered as an excellent alternative raw material. A biorefinery uses biomass and produces fuel, energy and value-added chemicals. The biorefinery is an emerging field and requires much development to compete with already established petroleum-based industries. One of the greatest challenges to the biorefinery is that the raw material; biomass, has a complex chemical composition and physical structure. A pretreatment process is necessary to induce physico-chemical changes in the biomass and transform it into easily digestible material. The main factor limiting enzymatic digestion of biomass is accessibility to chemical constituents. Steam Explosion (SE) pretreatment is a promising process that has many potential benefits compared to the alternatives, e.g. it has less hazardous process chemicals and conditions, less environmental impact, fewer energy requirements and lower capital investment.Existing literature on the SE process mainly concerns products obtained after the process. Knowledge about the physical processes that take place during the SE pretreatment is limited. This licentiate thesis is based on experimental and modelling studies performed with the aim of gaining knowledge of the basic mechanisms of this process. The SE is a three-step process that involves; (i) treatment of wood with pressurized steam for a specific period of time, (ii) explosion of wood chips through the rapid release of pressure, and (iii) impact of softened wood chips with other chips and vessel walls. In the experimental part these steps have been carefully isolated and the effects of these steps on internal and external structures of single spruce wood pieces have been studied. The effect of vapour expansion and the creation of stresses during the explosion step on a single cell of spruce wood (with four layers; P, S1, S2 and S3) at high temperature and moisture content have been modelled using the Finite Element Method.The study reveals that all the steps of the SE process contribute to structural changes in the wood material and increase pore size which increases the accessibility of chemical reagents and enzymes. A wood piece disintegrates into smaller pieces during the impact step. The vapour expansion inside cells during the explosion step causes each cell to expand in all directions and creates high stress and strain fields perpendicular to the cell direction. In general, cell wall damage is more likely to occur in cells with thin walls, i.e. earlywood; damaged P, S1 and S3 layers; low MFAs; irregular cross-sections and sharp corners.
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| 2. |
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| 3. |
- Tamminen, T., et al.
(författare)
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Mobile and flexible processing of biomass – EU project Mobile Flip
- 2015
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Ingår i: VTT Technology. - 2242-1211. ; , s. 28-41
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Konferensbidrag (refereegranskat)abstract
- EU project MOBILE FLIP in the SPIRE program aims at developing and demonstrating mobile processes for the treatment of underexploited agro- and forest based biomass resources into products and intermediates. The processes are evaluated in terms of raw material flexibility, as the biomass resources are typically scattered and seasonal. Process concepts have been designed around the key technologies pelletizing, torrefaction, slow pyrolysis, hydrothermal pretreatment and carbonisation. The products vary depending on the process concept, being typically fuels as such or for co-combustion (pellets, torrefied pellets, biocoals), biochars for soil remediation, biodegradable pesticides for agricultural or forestry use or chemicals for wood panel industry and sugars and hydrolysable cellulose as intermediate for the sugar platform. The concept evaluations are supported both by research and industrial (SME and large industries) partners in the whole value chains. Dissemination, communication and exploitation activities are an integral part of the project. Life-cycle analysis and a wide sustainability evaluation (economic, environmental and social assessment) are carried out for the process concepts in order to clarify their potential for flexible raw material valorisation. The partners are represented by the coauthors in this presentation: four SMEs, two large companies, six research organizations. The project duration is four years and total budget approximately EUR 10 million.
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| 4. |
- Zackrisson, Martin, et al.
(författare)
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Scan-o-matic: High-Resolution Microbial Phenomics at a Massive Scale
- 2016
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Ingår i: G3: Genes, Genomes, Genetics. - : Oxford University Press (OUP). - 2160-1836. ; 6:9, s. 3003-3014
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Tidskriftsartikel (refereegranskat)abstract
- The capacity to map traits over large cohorts of individuals—phenomics—lags far behind the explosive development in genomics. For microbes, the estimation of growth is the key phenotype because of its link to fitness. We introduce an automated microbial phenomics framework that delivers accurate, precise, and highly resolved growth phenotypes at an unprecedented scale. Advancements were achieved through the introduction of transmissive scanning hardware and software technology, frequent acquisition of exact colony population size measurements, extraction of population growth rates from growth curves, and removal of spatial bias by reference-surface normalization. Our prototype arrangement automatically records and analyzes close to 100,000 growth curves in parallel. We demonstrate the power of the approach by extending and nuancing the known salt-defense biology in baker’s yeast. The introduced framework represents a major advance in microbial phenomics by providing high-quality data for extensive cohorts of individuals and generating well-populated and standardized phenomics databases
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| 5. |
- Apelgren, Peter, et al.
(författare)
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In Vivo Human Cartilage Formation in Three-Dimensional Bioprinted Constructs with a Novel Bacterial Nanocellulose Bioink
- 2019
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Ingår i: Acs Biomaterials Science & Engineering. - : American Chemical Society (ACS). - 2373-9878. ; 5:5, s. 2482-2490
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial nanocellulose (BNC) is a 3D network of nanofibrils exhibiting excellent biocompatibility. Here, we present the aqueous counter collision (ACC) method of BNC disassembly to create bioink with suitable properties for cartilage-specific 3D-bioprinting. BNC was disentangled by ACC, and fibril characteristics were analyzed. Bioink printing fidelity and shear-thinning properties were evaluated. Cell-laden bioprinted grid constructs (5 X 5 X 1 mm(3)) containing human nasal chondrocytes (10 M mL(-1)) were implanted in nude mice and explanted after 30 and 60 days. Both ACC and hydrolysis resulted in significantly reduced fiber lengths, with ACC resulting in longer fibrils and fewer negative charges relative to hydrolysis. Moreover, ACC-BNC bioink showed outstanding printability, postprinting mechanical stability, and structural integrity. In vivo, cell-laden structures were rapidly integrated, maintained structural integrity, and showed chondrocyte proliferation, with 32.8 +/- 13.8 cells per mm(2) observed after 30 days and 85.6 +/- 30.0 cells per mm(2) at day 60 (p = 0.002). Furthermore, a full-thickness skin graft was attached and integrated completely on top of the 3D-bioprinted construct. The novel ACC disentanglement technique makes BNC biomaterial highly suitable for 3D-bioprinting and clinical translation, suggesting cell-laden 3D-bioprinted ACC-BNC as a promising solution for cartilage repair.
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| 6. |
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| 7. |
- Singh, Shikha, et al.
(författare)
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Orientation of Polylactic Acid–Chitin Nanocomposite Films via Combined Calendering and Uniaxial Drawing: Effect on Structure, Mechanical, and Thermal Properties
- 2021
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 11:12
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Tidskriftsartikel (refereegranskat)abstract
- The orientation of polymer composites is one way to increase the mechanical properties of the material in a desired direction. In this study, the aim was to orient chitin nanocrystal (ChNC)-reinforced poly(lactic acid) (PLA) nanocomposites by combining two techniques: calendering and solid-state drawing. The effect of orientation on thermal properties, crystallinity, degree of orientation, mechanical properties and microstructure was studied. The orientation affected the thermal and structural behavior of the nanocomposites. The degree of crystallinity increased from 8% for the isotropic compression-molded films to 53% for the nanocomposites drawn with the highest draw ratio. The wide-angle X-ray scattering results confirmed an orientation factor of 0.9 for the solid-state drawn nanocomposites. The mechanical properties of the oriented nanocomposite films were significantly improved by the orientation, and the pre-orientation achieved by film calendering showed very positive effects on solid-state drawn nanocomposites: The highest mechanical properties were achieved for pre-oriented nanocomposites. The stiffness increased from 2.3 to 4 GPa, the strength from 37 to 170 MPa, the elongation at break from 3 to 75%, and the work of fracture from 1 to 96 MJ/m3. This study demonstrates that the pre-orientation has positive effect on the orientation of the nanocomposites structure and that it is an extremely efficient means to produce films with high strength and toughness.
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| 8. |
- Sämfors, Sanna, 1987, et al.
(författare)
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Biofabrication of bacterial nanocellulose scaffolds with complex vascular structure
- 2019
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Ingår i: Biofabrication. - : IOP Publishing. - 1758-5082 .- 1758-5090. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial nanocellulose (BNC) has proven to be an effective hydrogel-like material for different tissue engineering applications due to its biocompatibility and good mechanical properties. However, as for all biomaterials, in vitro biosynthesis of large tissue constructs remains challenging due to insufficient oxygen and nutrient transport in engineered scaffold-cell matrices. In this study we designed, biofabricated and evaluated bacterial nanocellulose scaffolds with a complex vascular mimetic lumen structure. As a first step a method for creating straight channeled structures within a bacterial nanocellulose scaffold was developed and evaluated by culturing of Human Umbilical Vein Endothelial Cells (HUVECs). In a second step, more complex structures within the scaffolds were produced utilizing a 3D printer. A print mimicking a vascular tree acted as a sacrificial template to produce a network within the nanoporous bacterial nanocellulose scaffolds that could be lined with endothelial cells. In a last step, a method to produce large constructs with interconnected macro porosity and vascular like lumen structure was developed. In this process patient data from x-ray computed tomography scans was used to create a mold for casting a full-sized kidney construct. By showing that the 3D printing technology can be combined with BNC biosynthesis we hope to widen the opportunities of 3D printing, while also enabling the production of BNC scaffolds constructs with tailored vascular architectures and properties.
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| 9. |
- Apelgren, Peter, et al.
(författare)
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Skin Grafting on 3D Bioprinted Cartilage Constructs In Vivo
- 2018
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Ingår i: Plastic and Reconstructive Surgery - Global Open. - 2169-7574. ; 6:9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Three-dimensional (3D) bioprinting of cartilage is a promising new technique. To produce, for example, an auricle with good shape, the printed cartilage needs to be covered with skin that can grow on the surface of the construct. Our primary question was to analyze if an integrated 3D bioprinted cartilage structure is a tissue that can serve as a bed for a full-thickness skin graft. Methods: 3D bioprinted constructs (10x10x1.2mm) were printed using nanofibrillated cellulose/alginate bioink mixed with mesenchymal stem cells and adult chondrocytes and implanted subcutaneously in 21 nude mice. Results: After 45 days, a full-thickness skin allograft was transplanted onto the constructs and the grafted construct again enclosed subcutaneously. Group 1 was sacrificed on day 60, whereas group 2, instead, had their skin-bearing construct uncovered on day 60 and were sacrificed on day 75 and the explants were analyzed morphologically. The skin transplants integrated well with the 3D bioprinted constructs. A tight connection between the fibrous, vascularized capsule surrounding the 3D bioprinted constructs and the skin graft were observed. The skin grafts survived the uncovering and exposure to the environment. Conclusions: A 3D bioprinted cartilage that has been allowed to integrate in vivo is a sufficient base for a full-thickness skin graft. This finding accentuates the clinical potential of 3D bioprinting for reconstructive purposes.
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| 10. |
- Apelgren, Peter, et al.
(författare)
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Vascularization of tissue engineered cartilage-Sequential in vivo MRI display functional blood circulation
- 2021
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 276
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Tidskriftsartikel (refereegranskat)abstract
- Establishing functional circulation in bioengineered tissue after implantation is vital for the delivery of oxygen and nutrients to the cells. Native cartilage is avascular and thrives on diffusion, which in turn depends on proximity to circulation. Here, we investigate whether a gridded three-dimensional (3D) bioprinted construct would allow ingrowth of blood vessels and thus prove a functional concept for vascularization of bioengineered tissue. Twenty 10 x 10 x 3-mm 3Dbioprinted nanocellulose constructs containing human nasal chondrocytes or cell-free controls were subcutaneously implanted in 20 nude mice. Over the next 3 months, the mice were sequentially imaged with a 7 T small-animal MRI system, and the diffusion and perfusion parameters were analyzed. The chondrocytes survived and proliferated, and the shape of the constructs was well preserved. The diffusion coefficient was high and well preserved over time. The perfusion and diffusion patterns shown by MRI suggested that blood vessels develop over time in the 3D bioprinted constructs; the vessels were confirmed by histology and immunohistochemistry. We conclude that 3D bioprinted tissue with a gridded structure allows ingrowth of blood vessels and has the potential to be vascularized from the host. This is an essential step to take bioengineered tissue from the bench to clinical practice.
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| 11. |
- Lindahl, Anders, 1954, et al.
(författare)
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Cartilage and Bone Regeneration
- 2014
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Ingår i: Tissue Engineering: Second Edition. - Amsterdam : Elsevier, Inc.. ; , s. 529-582
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Bokkapitel (refereegranskat)abstract
- This chapter deals with the tissue engineering aspects of one of the mesenchymal tissues-cartilage. It includes a brief description of the different cartilage types and their embryonal origin. Tissue structures including chondrocyte and extracellular matrix components are described in detail. The disease aspect of hyaline cartilage with emphasis on cartilage injuries and the tissue engineering approach to cartilage regeneration with the autologous chondrocyte implantation technique is described in depth. The future aspects of cartilage regeneration techniques with potential cell types other than autologous chondrocytes as well as new promising scaffold techniques are described. © 2015 Elsevier Inc. All rights reserved.
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| 12. |
- Ortiz Catalan, Max Jair, 1982, et al.
(författare)
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Self-Contained Neuromusculoskeletal Arm Prostheses
- 2020
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 382:18, s. 1732-1738
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Tidskriftsartikel (refereegranskat)abstract
- After transhumeral amputation, four patients had implantation of a self-contained, osseointegrated prosthesis with a neuromusculoskeletal interface that allowed intuitive control of the prosthetic hand and arm over 3 to 7 years. A video shows use of the prostheses in daily life. We report the use of a bone-anchored, self-contained robotic arm with both sensory and motor components over 3 to 7 years in four patients after transhumeral amputation. The implant allowed for bidirectional communication between a prosthetic hand and electrodes implanted in the nerves and muscles of the upper arm and was anchored to the humerus through osseointegration, the process in which bone cells attach to an artificial surface without formation of fibrous tissue. Use of the device did not require formal training and depended on the intuitive intent of the user to activate movement and sensory feedback from the prosthesis. Daily use resulted in increasing sensory acuity and effectiveness in work and other activities of daily life. (Funded by the Promobilia Foundation and others.)
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| 13. |
- Säljö, Karin, 1981, et al.
(författare)
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Successful engraftment, vascularization, and In vivo survival of 3D-bioprinted human lipoaspirate-derived adipose tissue
- 2020
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Ingår i: Bioprinting. - : Elsevier BV. - 2405-8866. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Autologous fat grafting is commonly used for correction of soft-tissue deformities, despite a high rate of graft resorption and nutrition-supply challenges. Three-dimensional (3D)-bioprinting techniques enable tailor-made architecture of grafts and promote vascularization. In recent years, the importance of adipose tissue-derived stromal/stem cells (ASCs) for graft survival has become evident. This study investigated the printability of mechanically processed lipoaspirate containing ASCs, as well as in vivo survival and neovascularisation of the 3D-bioprinted grafts. Human lipoaspirate-derived adipose tissue was 3D bioprinted in alginate/nanocellulose bioink, implanted into nude mice, and harvested at days 3, 7, and 30, respectively. The processed lipoaspirate showed high viability and good printability when combined with alginate/nanocellulose, and the 3D-bioprinted grafts contained intact vascular structures and a high density of mature adipocytes before and after engraftment. After 30 days in vivo, novel blood vessels were present on the graft surface, showing signs of angiogenesis into the graft, as well as vascularization in the centre of the tissue. Moreover, histologic and immunohistochemical characterisation confirmed the presence of potential ASCs during the first week in vivo. These results demonstrated that human lipoaspirate-derived adipose tissue showed high printability, survived 3D bioprinting and engraftment in vivo, and displayed macroscopic and microscopic evidence of vascularization.
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| 14. |
- Abid, Suleman, et al.
(författare)
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Synthesis and characterization of glycol chitosan coated selenium nanoparticles acts synergistically to alleviate oxidative stress and increase ginsenoside content in Panax ginseng
- 2021
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 267
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the present study is synthesis of glycol chitosan coated selenium nanoparticles (GC-Se NPs) and evaluation of oxidative stress and ginsenoside accumulation in P. ginseng C. A. Meyer. We synthesized (Se NPs and GC-Se NPs) and characterized using various spectroscopic analyses. The highest concentration (20 mg L−1) of GC-Se NPs induced moderate ROS (O2[rad]− and H2O2) accumulation and upregulation of PgSOD and PgCAT showing good biocompatibility and less toxicity at the highest concentration. Furthermore, ginsenoside biosynthetic pathway genes (PgHMGR, PgSS, PgSE, PgDDS) also showed significant upregulation upon 20 mg L−1 GC-Se NPs treatment. At 20 mg L−1 GC-Se NPs treatment, ginsenoside accumulated upto 217.47 mg/mL and 169.86 mg/mL mainly due to the increased proportion of Rb1 and Re ginsenosides. Altogether, our results suggested that ecofriendly conjugation of GC with Se NPs could be used as a bio fortifier to enhance the ginsenoside profile and to increase the quality of ginseng roots.
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| 15. |
- Alerstam, Erik, et al.
(författare)
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Parallel computing with graphics processing units for high-speed Monte Carlo simulation of photon migration.
- 2008
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668. ; 13:6
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Tidskriftsartikel (refereegranskat)abstract
- General-purpose computing on graphics processing units (GPGPU) is shown to dramatically increase the speed of Monte Carlo simulations of photon migration. In a standard simulation of time-resolved photon migration in a semi-infinite geometry, the proposed methodology executed on a low-cost graphics processing unit (GPU) is a factor 1000 faster than simulation performed on a single standard processor. In addition, we address important technical aspects of GPU-based simulations of photon migration. The technique is expected to become a standard method in Monte Carlo simulations of photon migration.
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| 16. |
- Alerstam, Erik, et al.
(författare)
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White Monte Carlo for time-resolved photon migration.
- 2008
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Ingår i: Journal of Biomedical Optics. - : SPIE-Intl Soc Optical Eng. - 1083-3668. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- A novel scheme for fully scalable White Monte Carlo (WMC) has been developed and is used as a forward solver in the evaluation of experimental time-resolved spectroscopy. Previously reported scaling problems are avoided by storing detection events individually, turning spatial and temporal binning into post-simulation activities. The approach is suitable for modeling of both interstitial and noninvasive settings (i.e., infinite and semi-infinite geometries). Motivated by an interest in in vivo optical properties of human prostate tissue, we utilize WMC to explore the low albedo regime of time-domain photon migration--a regime where the diffusion approximation of radiative transport theory breaks down, leading to the risk of overestimating both reduced scattering (mu(s)') and absorption (mu(a)). Experimental work supports our findings and establishes the advantages of Monte Carlo-based evaluation.
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| 17. |
- Amoroso, Matteo, 1984, et al.
(författare)
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Functional and morphological studies of in vivo vascularization of 3D-bioprinted human fat grafts
- 2021
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Ingår i: Bioprinting. - : Elsevier BV. - 2405-8866. ; 23
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Tidskriftsartikel (refereegranskat)abstract
- Three-dimensional (3D) bioprinting offers the ability to design and biofabricate 3D structures based on autologous fat; however, the lack of vascularization in larger 3D-bioprinted constructs represents a limiting factor that hampers translation of this technology from bench to bedside. 3D bioprinting using microfractured fat mixed with nanocellulose–alginate hydrogel can promote vascularization through connections of fragments of vessels included in the fat. In this study, we determined the perfusion and diffusion characteristics of 3D-bioprinted fat constructs using magnetic resonance imaging (MRI) and assessed correlations between perfusion and angiogenesis within the printed constructs. Microfractured human fat from liposuction was printed with tunicate nanocellulose–alginate hydrogel, followed by transplantation of the constructs (10 × 10 × 3 mm) into nude mice that underwent longitudinal MRI for up to 99 days. Confirmation of vascularization was undertaken using immunohistochemical and histologic analyses. Before implantation, the constructs contained abundant fat tissue and fragments of human blood vessels (CD31+ and Ku80+), with subsequent in vivo MRI analysis following transplantation indicating low perfusion and suggesting their continued survival mainly by diffusion. Additionally, we observed a high diffusion coefficient (~2 × 10−3 mm2/s) that was preserved throughout the observation period. Following explantation, evaluation revealed that the constructs displayed preserved histology along with a mixture of human (Ku80+) and murine (Ku80−) erythrocyte-containing vessels. These results demonstrated successful interconnection of blood-vessel fragments from microfractured human fat via angiogenesis to form a vascular network with the host circulation, thereby confirming vascularization of the 3D-bioprinted fat constructs.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- Atefyekta, Saba, 1987
(författare)
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Antibacterial Surfaces for Biomedical Applications
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Medical devices such as orthopedic implants are intended to serve for improved quality of life. However, clinical success cannot be taken for granted and the most common reason for failure is due to biomaterials associated infection (BAI). An implantation surgical site is a susceptible environment for bacterial colonization, which in combination with compromised immune system, results in that bacteria can develop biofilms on the implant surface or in adjacent tissue. Once such a biofilm has established, it may lead to an infection that cannot be eradicated by means of traditional antibiotics, often resulting in revision surgery. Wounds after post implantation surgery is another risk for bacterial colonization into underlying tissue and increases further the susceptibility to infection. These and other bacteria related complications are today becoming more serious due to the rapid increase of antibiotic resistance worldwide. This has resulted in that many available antibiotics are losing their potency against bacteria and consequently, treating an infection with antibiotics is not working as effectively as in the past. The objective of this thesis was to find new solutions to address the complications associated with bacterial colonization through applying preventive measures by designing antibacterial surfaces for inhibition of early biomaterials associated and wound infection. For this purpose, two types of antibacterial surfaces were designed and evaluated. In the first type, a local drug-delivery system based on mesoporous Titania thin films were developed. These films were to serve as implant coatings where antibiotics are released locally at the implantation site to prevent biofilm formation and subsequent tissue colonization. In the second approach, antibacterial surfaces were developed through covalent immobilization of a cationic antimicrobial peptide (AMP), thus creating surfaces that kill bacteria upon contact. The overall results in this thesis, which are presented as four papers, suggest that the developed antibacterial surfaces are promising to use in future biomedical applications.
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| 22. |
- Atefyekta, Saba, 1987, et al.
(författare)
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Antibiofilm elastin-like polypeptide coatings: functionality, stability, and selectivity
- 2019
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Ingår i: Acta Biomaterialia. - : Elsevier BV. - 1878-7568 .- 1742-7061. ; 83, s. 245-256
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial peptides (AMPS) are currently receiving interest as an alternative to conventional antibiotics to treat biomaterial-associated infection. However, the inherent instability of such peptides often limits their efficacy in intended clinical applications. Covalent immobilization of AMPs to surfaces is one strategy to increase the long-term stability and minimize the toxicity. In this work, an antimicrobial peptide, RRPRPRPRPWWWW-NH2 (RRP9W4N), was used to modify elastin-like polypeptide (ELP) surface coatings containing cell-adhesive peptide domains (RGD) using covalent chemistry. The AMP retained its antibacterial activity against Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa when covalently bonded to ELP surfaces. Simultaneously, the AMP functionalization had insignificant effect on the viability, function, and differentiation of human osteosarcoma MG63 cells and human mesenchymal stem cells (hMSCs). Furthermore, stability of the immobilized AMP in human blood serum was investigated, and the results suggested that the AMP preserved its antibacterial activity up to 24 h. Combined, the results show that covalently attached AMPs onto RGD-containing ELP are an excellent candidate as an antimicrobial coating for medical devices.
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| 23. |
- Balian, Alien, et al.
(författare)
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Nucleases as molecular targets for cancer diagnosis
- 2021
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Ingår i: Biomarker Research. - : BMC. - 2050-7771. ; 9:1
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Forskningsöversikt (refereegranskat)abstract
- Early cancer diagnosis is a crucial element to improved treatment options and survival. Great research efforts have been made in the search for better performing cancer diagnostic biomarkers. However, the quest continues as novel biomarkers with high accuracy for an early diagnosis remain an unmet clinical need. Nucleases, which are enzymes capable of cleaving nucleic acids, have been long considered as potential cancer biomarkers. The implications of nucleases are key for biological functions, their presence in different cellular counterparts and catalytic activity led the enthusiasm towards investigating the role of nucleases as promising cancer biomarkers. However, the most essential feature of these proteins, which is their enzymatic activity, has not been fully exploited. This review discusses nucleases interrogated as cancer biomarkers, providing a glimpse of their physiological roles. Moreover, it highlights the potential of harnessing the enzymatic activity of cancer-associated nucleases as a novel diagnostic biomarker using nucleic acid probes as substrates.
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| 24. |
- Björnham, Oscar, 1976-, et al.
(författare)
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Measurements of the binding force between the Helicobacter pylori adhesin BabA and the Lewis b blood group antigen using optical tweezers
- 2005
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Ingår i: Journal of Biomedical Optics. - Bellingham, WA : SPIE-Intl Soc Optical Eng. - 1083-3668 .- 1560-2281. ; 10:4, s. 044024-044032
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Tidskriftsartikel (refereegranskat)abstract
- Helicobacter pylori is a world-wide spread bacterium that causes persistent infections and chronic inflammations that can develop into gastritis and peptic ulcer disease. It expresses several adhesin proteins on its surface that bind to specific receptors in the gastric epithelium. The most well-known adhesin is BabA, which has previously been shown to bind specifically to the fucosylated blood group antigen Lewis b (Leb). The adhesion forces between BabA and the Leb antigen are investigated in this work and assessed by means of optical tweezers. A model system for in situ measurements of the interaction forces between individual bacteria and beads coated with Leb is developed. It is found that the de-adhesion force in this model system, measured with a loading rate of ~100 pN/s, ranges from 20 to 200 pN. The de-adhesion force appears predominantly as multiples of an elementary force, which is determined to 25±1.5 pN and identified as the unbinding force of an individual BabA-Leb binding. It is concluded that adhesion in general is mediated by a small number of bindings (most often 1 to 4) despite that the contact surface between the bacterium and the bead encompassed significantly more binding sites.
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| 25. |
- Broos, Sissela, et al.
(författare)
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Synergistic augmentation of CD40-mediated activation of antigen-presenting cells by amphiphilic poly(γ-glutamic acid) nanoparticles.
- 2012
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Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 33:26, s. 6230-6239
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Tidskriftsartikel (refereegranskat)abstract
- Agonistic anti-CD40 monoclonal antibodies (mAbs) hold great potential for cancer immunotherapy. However, systemic administration of anti-CD40 mAbs can be associated with severe side effects, such as cytokine release syndrome and liver damage. With the aim to increase the immunostimulatory potency as well as to achieve a local drug retention of anti-CD40 mAbs, we linked an agonistic mAb to immune activating amphiphilic poly(γ-glutamic acid) nanoparticles (γ-PGA NPs). We demonstrate that adsorption of anti-CD40 mAb to γ-PGA NPs (anti-CD40-NPs) improved the stimulatory capacity of the CD40 agonist, resulting in upregulation of costimulatory CD80 and CD86 on antigen-presenting cells, as well as IL-12 secretion. Interestingly, anti-CD40-NPs induced strong synergistic proliferative effects in B cells, possibly resulting from a higher degree of CD40 multimerization, enabled by display of multiple anti-CD40 mAbs on the NPs. In addition, local treatment with anti-CD40-NPs, compared to only soluble CD40 agonist, resulted in a significant reduction in serum levels of IL-6, IL-10, IL-12 and TNF-α in a bladder cancer model. Taken together, our results suggest that anti-CD40-NPs are capable of synergistically enhancing the immunostimulatory effect induced by the CD40 agonist, as well as minimizing adverse side effects associated with systemic cytokine release. This concept of nanomedicine could play an important role in localized immunotherapy of cancer.
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| 26. |
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| 27. |
- Chen, DeJiu, Associate Professor, et al.
(författare)
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Analyzing Dynamic Operational Conditions of Limb Prosthetic Sockets with a Mechatronics-Twin Framework
- 2022
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 12:3, s. 986-986
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Tidskriftsartikel (refereegranskat)abstract
- Lower limb prostheses offer a solution to restore the ambulation and self-esteem of amputees. One key component is the prosthetic socket that serves as the interface between prosthetic device and amputee stump and thereby has a wide range of impacts on efficient fitting, appropriate load transmission, operational stability, and control. For the design and optimization of a prosthetic socket, an understanding of the actual intra-socket operational conditions becomes therefore necessary. This is however a difficult task due to the inherent complexity and restricted observability of socket operation. In this study, an innovative mechatronics-twin framework that integrates advanced biomechanical models and simulations with physical prototyping and dynamic operation testing for effective exploration of operational behaviors of prosthetic sockets with amputees is proposed. Within this framework, a specific Stewart manipulator is developed to enable dynamic operation testing, in particular for a well-managed generation of dynamic intra-socket loads and behaviors that are otherwise difficult to observe or realize with the real amputees. A combination of deep learning and Bayesian Inference algorithms is then employed for analyzing the intra-socket load conditions and revealing possible anomalous.
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| 28. |
- Chen, Jingjing
(författare)
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Heat-transfer Enhancement for Slurries from Biogas Plants− Properties, processes, and thermal systems
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biomethane production from renewable residues with anaerobic digestion gains increasing attention as a crucial alternative to petroleum fuels. It has been vigorously developed, but the large amounts of subsidy from the government indicate that the process efficiency needs to be further improved. For biomethane production, on the one hand, a great amount of heat needs to be used for heating the feeding slurry, sanitation of slurry, and maintaining the temperature in the large-scale reactors. On the other hand, a large amount of thermophilic effluent slurries brings a huge amount of waste heat, which can be recovered. This makes it important to study how to increase production by improving the thermal efficiency of biogas plants with novel heat exchangers. The working fluids in the biogas plants are the non-Newtonian and high-viscous slurries, and the conventional heat exchangers in biogas plants always show much lower performance compared to those in other industries. Normally, the slurries in the biogas plant consist of different substrates, including straw, manure, food waste, municipal sludge, and their mixtures, and various factors such as the amount and type of solids, particle size, shear rate, and temperature impact the rheological properties of the slurries, which makes the complexity in the rheological properties and the difficulty in developing novel heat exchangers.The development of heat exchangers calls for the rheological properties of slurries. However, to the best of our knowledge, only the rheology of manure slurry was systematically determined and modeled considering the effect of temperature. The lack of the rheological properties of slurries further hinders the design and development of novel geometries to enhance the heat transfer of the slurries. Correspondingly, the quantitative contribution and potential of the waste-heat recovery from the slurries to production using the enhanced geometry remain unclear. In this thesis work, to design novel geometry with heat-transfer enhancement for different slurries and determine its potential in thermal cycles in the full-scale biogas plants, firstly, the temperature-dependent rheological properties of the slurries, including the corn straw, food waste, and mixed slurries, were tested and modeled. It was found that these slurries possess strong shear-thinning behavior, the temperature has a significant impact on their dynamic viscosity, and the power-law model combined with the Arrhenius equation can describe the rheology well. Subsequently, with the reliable models of the rheological properties as the key input, Computational Fluid Dynamics simulations were conducted to screen different twisted geometries, determine the heat-transfer performance, and reveal the mechanism of the heat-transfer enhancement. Lab- and pilot-scale experiments were also conducted to validate the numerical results. The twisted hexagonal tubes show a positive enhancement factor up to 2.6 compared to normal heat exchangers in a wide range of operating conditions. The continuous and strong near-wall shear effect is the intrinsic reason for achieving a significant heat-transfer enhancement in the twisted hexagonal tubes. Moreover, the generalized engineering equations for predicting the effective shear rate and heat-transfer performance with measurable parameters were established and verified with both numerical and experimental results. Finally, the twisted-hexagonal-tube heat exchange was integrated with complete thermal cycles, including waste-heat recovery and external heating processes in the biogas plant, and the potential of increased production and profits were modeled and analyzed combined with the practical operating conditions in a full-scale biogas plant. It was found that for the waste-heat recovery using the twisted hexagonal tubes, the net raw biogas production can increase by up to 17.0 %, and for the external heating process, the increased profit equivalent to 39 % of total production can be achieved owing to energy conservation in external heating using the twisted-hexagonal-tube heat exchangers for a full-scale biogas plant.
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| 29. |
- Cruz, Javier, 1990-
(författare)
-
Microfluidics for High-Pressure Inertial Focusing : Focusing, Separation and Concentration of Micro and Sub-micron Particles
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The birth of microsystems set the ground for technologies never imagined before, for it is not only the small size what characterizes the miniaturized systems, but unique phenomena arise in the micro scale. This thesis relates to one such unique phenomenon, inertial focusing, a phenomenon that occurs in microfluidic systems if very special conditions are met and that allows for fine manipulation of particles in fluid samples. This ability is key in a bigger picture: the analysis of complex fluids, where rare particles of interest may be present in very few numbers amongst a myriad of others, making the task difficult – if not impossible. A system exploiting inertial focusing allows, for instance, to focus, separate, isolate and concentrate such rare particles of interest, and even to transfer them to another fluid, thereby enabling/facilitating their detection and analysis. Examples of rare particles of interest in complex fluids are circulating tumor cells in blood, that give away the presence of cancer, extracellular vesicles also in blood, that contain biomarkers with physiological and pathological information about the patient, or bacteria in natural water, where the species present and their numbers are to be monitored for safety reasons and/or biological studies. This thesis covers the state of art physical principles behind the phenomenon and extends the understanding both in theory and applications. Specifically, the technology is extended to allow for manipulation of sub-micron particles, a range of interest as it comprises bacteria, viruses and organelles of eukaryotic cells. This was possible by an analysis of the balance of forces in play and by the integration of inertial focusing in high-pressure systems (up to 200 bar). In a second block, a very special line of inertial focusing is introduced and developed; inertial focusing in High Aspect Ratio Curved (HARC) microfluidics. These systems, engineered to rearrange the force field responsible for the particle manipulation, not only achieve excellent performances for focusing and concentration of particles, but also extreme resolution in their separation (mathematically unlimited; demonstrated experimentally for differences in size down to 80 nm). Perhaps more important than the performance, the systems are stable, intuitive and simpler to design, attributes that we hope will make the technology and its outstanding benefits more accessible to the community. With its remarkable performance, it would not come as a surprise if, in the near future, inertial focusing makes a strong impact on how analyses are performed nowadays and opens up for possibilities beyond the current state of the art.
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| 30. |
- Dainiak, Maria B, et al.
(författare)
-
Gelatin-fibrinogen cryogel dermal matrices for wound repair: Preparation, optimisation and in vitro study.
- 2010
-
Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 31, s. 67-76
-
Tidskriftsartikel (refereegranskat)abstract
- Macroporous sponge-like gelatin-fibrinogen (Gl-Fg) scaffolds cross-linked with different concentrations (0.05-0.5%) of glutaraldehyde (GA) were produced using cryogelation technology, which allows for the preparation of highly porous scaffolds without compromising their mechanical properties, and is a more cost-efficient process than freeze-drying. The produced Gl-Fg-GA(X) scaffolds had a uniform interconnected open porous structure with a porosity of up to 90-92% and a pore size distribution of 10-120mum. All of the obtained cryogels were elastic and mechanically stable, except for the Gl-Fg-GA(0.05) scaffolds. Swelling kinetics and degradation rate, but not the porous structure of the cryogels, were strongly dependent on the degree of cross-linking. A ten-fold increase in the degree of cross-linking resulted in an almost 80-fold decrease in the rate of degradation in a solution of protease. Cryogels were seeded with primary dermal fibroblasts and the densities observed on the surface, plus the expression levels of collagen types I and III observed 5 days post-seeding, were similar to those observed on a control dermal substitute material, Integra((R)). Fibroblast proliferation and migration within the scaffolds were relative to the GA content. Glucose consumption rate was 3-fold higher on Gl-Fg-GA(0.1) than on Gl-Fg-GA(0.5) cryogels 10 days post-seeding. An enhanced cell motility on cryogels with reducing GA crosslinking was obtained after long time culture. Particularly marked cell infiltration was seen in gels using 0.1% GA as a crosslinker. The scaffold started to disintegrate after 42 days of in vitro culturing. The described in vitro studies demonstrated good potential of Gl-Fg-GA(0.1) scaffolds as matrices for wound healing.
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| 31. |
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| 32. |
- Depauw, V., et al.
(författare)
-
Sunlight-thin nanophotonic monocrystalline silicon solar cells
- 2017
-
Ingår i: Nano Futures. - : IOP Publishing. - 2399-1984. ; 1:2
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Introducing nanophotonics into photovoltaics sets the path for scaling down the surface texture of crystalline-silicon solar cells from the micro-to the nanoscale, allowing to further boost the photon absorption while reducing silicon material loss. However, keeping excellent electrical performance has proven to be very challenging, as the absorber is damaged by the nanotexturing and the sensitivity to the surface recombination is dramatically increased. Here we realize a light-wavelength-scale nanotextured monocrystalline silicon cell with the confirmed efficiency of 8.6% and an effective thickness of only 830 nm. For this we adopt a self-assembled large-area and industry-compatible amorphous ordered nanopatterning, combined with an advanced surface passivation, earning strongly enhanced solar light absorption while retaining efficient electron collection. This prompts the development of highly efficient flexible and semitransparent photovoltaics, based on the industrially mature monocrystalline silicon technology.
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| 33. |
- Dev, Apurba, et al.
(författare)
-
Electrokinetic effect for molecular recognition : A label-free approach for real-time biosensing
- 2016
-
Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 82, s. 55-63
-
Tidskriftsartikel (refereegranskat)abstract
- We present a simple and inexpensive method for label-free detection of biomolecules. The method monitors the changes in streaming current in a fused silica capillary as target biomolecules bind to immobilized receptors on the inner surface of the capillary. To validate the concept, we show detection and time response of different protein-ligand and protein-protein systems: biotin-avidin and biotin-streptavidin, barstar-dibarnase and Z domain-immunoglobulin G (IgG). We show that specific binding of these biomolecules can be reliably monitored using a very simple setup. Using sequential injections of various proteins at a diverse concentration range and as well as diluted human serum we further investigate the capacity of the proposed technique to perform specific target detection from a complex sample. We also investigate the time for the signal to reach equilibrium and its dependence on analyte concentration and demonstrate that the current setup can be used to detect biomolecules at a concentration as low as 100 pM without requiring any advanced device fabrication procedures. Finally, an analytical model based on diffusion theory has been presented to explain the dependence of the saturation time on the analyte concentration and capillary dimensions and how reducing length and inner diameter of the capillary is predicted to give faster detection and in practice also lower limit of detection.
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| 34. |
- Enejder, Annika, 1969, et al.
(författare)
-
SHG Imaging for Tissue Engineering Applications
- 2016
-
Ingår i: Second Harmonic Generation Imaging. - : CRC Press. - 9781439849156 - 9781439849149 ; , s. 409-426
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Treatment of lost tissue oen relies on transplantations, either of donor or of autologous tissue. Both alternatives have limitations; there is for example a limited supply of donor transplants, which also require immunosuppression therapy with possible side eects. Transplanted autologous tissue may lack some of the functions of the original tissue and the procedure may also introduce complications at the donor site. In some cases, articial substitutes manufactured from nonbiological materials can be used, for example, synthetic polymer blood vessels or joint replacement prostheses. However, these replacements have drawbacks such as risk for infections, limited material durability, and lack of mechanisms for repair, growth, and remodeling. For these reasons, development of advanced articial tissue constructs with adaptive capabilities is desirable.
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| 35. |
- Engberg, Anna E., 1982-, et al.
(författare)
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Inhibition of complement activation on a model biomaterial surface by streptococcal M protein-derived peptides
- 2009
-
Ingår i: Biomaterials. - : Elsevier. - 0142-9612 .- 1878-5905. ; 30:13, s. 2653-2659
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate a new approach to inhibit complement activation triggered by biomaterial surfaces in contact with blood. In order to inhibit complement activation initiated by the classical pathway (CP), we used streptococcal M protein-derived peptides that specifically bind human C4BP, an inhibitor of the CP. The peptides were used to coat polystyrene microtiter wells which served as a model biomaterial. The ability of coated peptides to bind C4BP and to attenuate complement activation via the CP (monitored as generation of fluid-phase C3a and binding of fragments of C3 and C4 to the surface) was investigated using diluted normal human serum, where complement activation by the AP is minimal, as well as serum from a patient lacking alternative pathway activation. Complement activation (all parameters) was significantly decreased in serum incubated in well surfaces coated with peptides. Total inhibition of complement activation was obtained at peptide coating concentrations as low as 1-5 mu g/mL. Successful use of Streptococcus-derived peptides shows that it is feasible to control complement activation at a model biomaterial surface by capturing autologous complement regulatory molecules from plasma. (C) 2009 Elsevier Ltd. All rights reserved.
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| 36. |
- Eriksson Linsmeier, Cecilia, et al.
(författare)
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Soft tissue reactions evoked by implanted gallium phosphide.
- 2008
-
Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 29:35, s. 4598-4604
-
Tidskriftsartikel (refereegranskat)abstract
- Neural devices may play an important role in the diagnosis and therapy of several clinical conditions, such as stroke, trauma or neurodegenerative disorders, by facilitating motor and pain control. Such interfaces, chronically implanted in the CNS, need to be biocompatible and have the ability to stimulate and record nerve signals. However, neural devices of today are not fully optimized. Nanostructured surfaces may improve electrical properties and lower evoked tissue responses. Vertical gallium phosphide (GaP) nanowires epitaxially grown from a GaP surface is one way of creating nanostructured electrodes. Thus, we chose to study the soft tissue reactions evoked by GaP surfaces. GaP and the control material titanium (Ti) were implanted in the rat abdominal wall for evaluation of tissue reactions after 1, 6, or 12 weeks. The foreign-body response was evaluated by measuring the reactive capsule thickness and by quantification of ED1-positive macrophages and total cells in the capsule. Furthermore, the concentration of Ga was measured in blood, brain, liver and kidneys. Statistically significant differences were noticed between GaP and Ti at 12 weeks for total and ED1-positive cell densities in the capsule. The chemical analysis showed that the concentration of Ga in brain, liver and kidneys increased during 12 weeks of implantation, indicating loss of Ga from the implant. Taken together, our results show that the biocompatible properties of GaP are worse than those of the well-documented biomaterial Ti.
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| 37. |
- Evenbratt, Hanne, 1980, et al.
(författare)
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ToF-SIMS imaging of dual biomolecular monolayer gradients
- 2020
-
Ingår i: Biointerphases. - : American Vacuum Society. - 1559-4106 .- 1934-8630. ; 15:6
-
Tidskriftsartikel (refereegranskat)abstract
- Precise characterization of a monolayer of two different biomolecules in a gradient pattern on a glass surface puts high demand on the method used. Some techniques can detect protein monolayers but not on a glass surface. Others can distinguish between different proteins but not identify a gradient pattern. Here, we used ToF-SIMS to validate the complete surface composition, checking all the necessary boxes. As these types of surfaces can dictate sensitive cell behaviors, the precision on a nanolevel is crucial, and to visualize and determine the molecular distribution become essential. The dual monolayer consisted of laminin 521 and one of three other biomolecules of different sizes, epidermal growth factor, growth differentiation factor 5, or bovine serum albumin, creating opposing gradient patterns. The resulting ToF-SIMS imaging and line scan data provided detailed information on the distribution of the adsorbed proteins.
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| 38. |
- Fallgren, Corina, et al.
(författare)
-
Venous shear stress enhances platelet mediated staphylococcal adhesion to artificial and damaged biological surfaces.
- 2002
-
Ingår i: Biomaterials. - 1878-5905. ; 23:23, s. 4581-4589
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated the role of blood components in the adhesion of staphylococci to biological and artificial surfaces under well-defined flow conditions by using the Cone and Plate(let) Analyzer. An enzyme-linked immunosorbent assay-like binding assay with biotinylated bacteria determined the extent of bacterial adhesion to subendothelial extracellular matrix (ECM), polystyrene (PS) and adult bovine aortic endothelial (ABAE) cell monolayer. The presence of adsorbed plasma proteins on PS and ECM did not increase and in some cases reduced staphylococcal adhesion under flow conditions (200s(-1)). However, their presence on ABAE cells increased bacterial adhesion but to a level still lower than the adhesion to PS and ECM. In contrast, adhered platelets significantly increased staphylococcal adhesion to both PS and ECM, but did not affect the adhesion to ABAE cells. Furthermore, bacterial adhesion to the platelets coated ECM and PS under flow conditions (200s(-1)) was increased by 1.4 to 2.6-fold compare to static conditions. The platelet-enhanced bacterial adhesion was markedly inhibited by blockade of the platelet GPIb receptor. In conclusion, staphylococcal extensive adhesion to ECM and PS surfaces is increased by venous flow and mediated by surface adhered activated platelets via a GPIb dependent mechanism. On the other hand, ABAE cells demonstrated limited bacterial adhesion that is mediated by adsorbed plasma proteins. Our results suggest that under physiological venous flow conditions the intact vessel wall is less prone for bacterial adhesion than damaged vessel wall.
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| 39. |
- Forsum, Oskar
(författare)
-
On plant responses to D-amino acids : features of growth, root behaviour and selection for plant transformation
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Amino acids have been regarded as potential plant nitrogen sources for more than a century. Some amino acids have been shown to support growth while others have growth-retarding effects. The D-isomers with notably adverse effects on plants’ growth and development include D-serine and D-alanine. Recently, D-serine has been recognised as an endogenous ligand of receptor channels mediating calcium fluxes in plants, but otherwise little is known about endogenous roles of D-amino acids in plants. In the studies underlying this thesis, the negative responses to D-serine and D-alanine were converted to positive effects in Arabidopsis thaliana (Arabidopsis) plants by introducing either of two D-amino acid-metabolising enzymes. Transgenic Arabidopsis lines expressing either the D-serine dehydratase (dsdA) gene from Escherichia coli or the D-amino acid oxidase (DAO1) gene from Rhodotorula gracilis grew with otherwise toxic D-amino acids as the sole nitrogen source. I also expressed a transporter specific for D-amino acids, which further increased the transgenic plants’ growth with D-serine as sole nitrogen source. Hence, both assimilation and uptake restrictions can limit plant growth on D-amino acids. The growth of transgenic lines on D-serine or D-alanine provides an unambiguous and highly visible phenotype, which is essential for a selectable marker. Thus, expressing of either the dsdA or DAO1 genes generated transformants that are easy to screen. Furthermore, the DAO1 gene can be readily used for either positive or negative selection, depending on the substrate, thus it provides a unique conditional, substrate-dependent positive/negative selectable marker for plant transformation. In summary, the presented work demonstrates that introducing the ability to catalyse a single metabolic step can allow plants to exploit an otherwise inaccessible or toxic form of organic nitrogen, and provides a versatile marker based on nitrogen nutrition for selecting transgenic plants. A possible role for D-serine in plants’ touch response is also reviewed in the thesis.
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| 40. |
- Freij-Larsson, Christina, et al.
(författare)
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Adsorption behaviour of amphiphilic polymers at hydrophobic surfaces: Effects on protein adsorption
- 1996
-
Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 17:22, s. 2199-2207
-
Tidskriftsartikel (refereegranskat)abstract
- The adsorption of four different amphiphilic polymers to a model surface has been studied, and the effects of the adsorbed amphiphiles on the subsequent adsorption of fibrinogen (Fg) and human serum albumin (HSA) at the surfaces were investigated. The amphiphilic polymers were one commercially available ABA block copolymer, Pluronic PE9400 (PE94), composed of poly(ethylene oxide) (A-blocks) and poly(propylene oxide) (B-block), and three graft copolymers, two with backbones of poly(styrene-co-acrylamide) (STY) and one with a backbone of poly(methyl methacrylate-co-ethylhexyl methacrylate) (ACRY). The backbones carried poly(ethylene oxide) (PEG) grafts, The model surface was a hydrophobic methylated silica surface (HMS). The amphiphilic polymers were adsorbed at the HMS surface from an ethanol/water solution. The adsorption process was monitored by ellipsometry. After rinsing with phosphate buffered saline (PBS), protein was added and the continued adsorption measured by ellipsometry. Surfaces modified by adsorption of the amphiphilic polymers were also characterized by contact angle measurements and X-ray photoelectron spectroscopy (XPS). According to these measurements the amphiphilic polymers adsorbed in significant amounts at the HMS surface. A limited study by atomic force microscopy (AFM), as well as the XPS measurements, suggests that both single molecules and micellar aggregates adsorb at the surface. ACRY and PE94 gave the highest levels of adsorption. As compared to the Pluronic block copolymer the graft copolymers were more strongly attached to the HMS surface, as shown by less desorption on rinsing with solvent. The ellipsometric results show that the adsorption of HSA and Fg at HMS surfaces containing preadsorbed amphiphilic polymer was significantly reduced as compared to the bare HMS surface. ACRY and PE94 showed the largest effects. Both polymers gave more than a 20-fold reduction of the Fg adsorption and a 10-fold reduction of the HSA adsorption. The STY polymers reduced the protein adsorption by a factor of 2-3.
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| 41. |
- Freij-Larsson, Christina, et al.
(författare)
-
Polyurethane surfaces modified by amphiphilic polymers: effects on protein adsorption
- 2000
-
Ingår i: Biomaterials. - 1878-5905. ; 21:3, s. 307-315
-
Tidskriftsartikel (refereegranskat)abstract
- Surface modification of polyurethane (PUR) surfaces was carried out by using three different amphiphilic polymers. Two of the polymers were graft copolymers, having backbones consisting of poly(methyl methacrylate-co-ethylhexyl acrylate) and poly(styrene-co-acrylamide), respectively, and poly(ethylene oxide) PEO 2000 grafts. The third polymer was a commercially available poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer, Pluronic 9400. The polymers were designated ACRY, STY2, and PE94, respectively. Surface modification was achieved by adsorption of the amphiphilic polymers at PUR surfaces from an aqueous solution, or by blending the amphiphiles into a PUR solution, followed by solution casting of films. The accumulation of the amphiphilic polymers at the PUR surfaces was observed by XPS and contact angle measurements. The ACRY and PE94 polymers were shown to adsorb poorly at the PUR surface, but gave strong surface effects when present in the PUR matrix. Protein adsorption was measured under static as well as under flow conditions. The modified surfaces had generally lower adsorption of blood proteins (HSA, Fg and IgG) than the unmodified PUR surfaces. ACRY blend modified surfaces had the lowest adsorption.
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| 42. |
- Gallagher, William M., et al.
(författare)
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Molecular basis of cell-biomaterial interaction: Insights gained from transcriptomic and proteomic studies
- 2006
-
Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 27:35, s. 5871-5882
-
Forskningsöversikt (refereegranskat)abstract
- With the growing interest in clinical interventions that involve medical devices, the role for new biomaterials in modern medicine is currently expanding at a phenomenal rate. Failure of most implant materials stems from an inability to predict and control biological phenomena, such as protein adsorption and cell interaction, resulting in an inappropriate host response to the materials. Contemporary advances in biological investigation are starting to shift focus in the biomaterials field, in particular with the advent of high-throughput methodologies for gene and protein expression profiling. Here, we examine the role that emerging transcriptomic and proteomic technologies could play in relation to biomaterial development and usage. Moreover, a number of studies are highlighted which have utilized such approaches in order to try to create a deeper understanding of cell-biomaterial interactions and, hence, improve our ability to predict and control the biocompatibility of new materials. (c) 2006 Elsevier Ltd. All rights reserved.
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| 43. |
- Ghaderi, Mohammadamir, 1986, et al.
(författare)
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Thermally regenerable optical transparent MEMS windows for exhaust gas analysis
- 2020
-
Ingår i: Optics InfoBase Conference Papers.
-
Konferensbidrag (refereegranskat)abstract
- Exhaust gas measurement in the harsh environment of the tailpipe by optical techniques is a highly robust technique, provided that optical access is maintained in the presence of soot. The design, fabrication, and testing of membranes in SiC-on-Si with integrated heaters to serve as a regenerable MEMS optical window into the tailpipe are presented. Membranes at slightly elevated temperatures are demonstrated to keep the surface transparent by thermophoresis, while surface regeneration is achieved at pulsed high temperatures, which allows long-term optical measurement in the exhaust.
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| 44. |
- Ghorbanpour, F., et al.
(författare)
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Marked point process analysis of epidermal nerve fibres
- 2021
-
Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 283:1, s. 41-50
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Tidskriftsartikel (refereegranskat)abstract
- Epidermal nerve fibre (ENF) density and summed length of ENFs per epidermal surface area are reduced, and ENFs may appear more clustered within the epidermis in subjects suffering from diabetic neuropathy compared to healthy subjects. Therefore, it is important to understand the spatial behaviour of ENFs in healthy and neuropathy subjects. By using confocal microscopy data , we study the spatial structure of epidermal nerves by regarding the nerve tree locations as realizations of marked point processes . The termination points of the fibres of a nerve tree are used to define a reactive territory which is taken as a mark for the nerve tree location. We study the differences in the spatial pattern of ENFs between healthy subjects and subjects suffering from mild diabetic neuropathy by using Ripley's K function and the mark correlation function. In addition, we propose a marked sequential point process model for the nerve tree locations. Data are replicated point patterns, where we have several patterns from each subject and from each group.
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| 45. |
- Gorpas, Dimitris, et al.
(författare)
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Evaluation of a radiative transfer equation and diffusion approximation hybrid forward solver for fluorescence molecular imaging
- 2012
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Ingår i: Journal of Biomedical Optics. - 1083-3668. ; 17:12
-
Tidskriftsartikel (refereegranskat)abstract
- The solution of the forward problem in fluorescence molecular imaging strongly influences the successful convergence of the fluorophore reconstruction. The most common approach to meeting this problem has been to apply the diffusion approximation. However, this model is a first-order angular approximation of the radiative transfer equation, and thus is subject to some well-known limitations. This manuscript proposes a methodology that confronts these limitations by applying the radiative transfer equation in spatial regions in which the diffusion approximation gives decreased accuracy. The explicit integro differential equations that formulate this model were solved by applying the Galerkin finite element approximation. The required spatial discretization of the investigated domain was implemented through the Delaunay triangulation, while the azimuthal discretization scheme was used for the angular space. This model has been evaluated on two simulation geometries and the results were compared with results from an independent Monte Carlo method and the radiative transfer equation by calculating the absolute values of the relative errors between these models. The results show that the proposed forward solver can approximate the radiative transfer equation and the Monte Carlo method with better than 95% accuracy, while the accuracy of the diffusion approximation is approximately 10% lower. (c) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JBO.17.12.126010]
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| 46. |
- Greene, George W., et al.
(författare)
-
Anisotropic dynamic changes in the pore network structure, fluid diffusion and fluid flow in articular cartilage under compression
- 2010
-
Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 31:12, s. 3117-3128
-
Tidskriftsartikel (refereegranskat)abstract
- A compression cell designed to fit inside an NMR spectrometer was used to investigate the in situ mechanical strain response, structural changes to the internal pore structure, and the diffusion and flow of interstitial water in full-thickness cartilage samples as it was deforming dynamically under a constant compressive load (pressure). We distinguish between the hydrostatic pressure acting on the interstitial fluid and the pore pressure acting on the cartilage fibril network. Our results show that properties related to the pore matrix microstructure such as diffusion and hydraulic conductivity are strongly influenced by the hydrostatic pressure in the interstitial fluid of the dynamically deforming cartilage which differ significantly from the properties measured under static i.e. equilibrium loading conditions (when the hydrostatic pressure has relaxed back to zero). The magnitude of the hydrostatic fluid pressure also appears to affect the way cartilage's pore matrix changes during deformation with implications for the diffusion and flow-driven fluid transport through the deforming pore matrix. We also show strong evidence for a highly anisotropic pore structure and deformational dynamics that allows cartilage to deform without significantly altering the axial porosity of the matrix even at very large strains. The insensitivity of the axial porosity to compressive strain may be playing a critical function in directing the flow of pressurized interstitial fluid in the compressed cartilage to the surface, to support the load, and provide a protective interfacial fluid film that 'weeps' out from the deforming tissue and thereby enhances the (elasto)hydrodynamic efficacy of sliding joints. Our results appear to show a close synergy between the structure of cartilage and both the hydrodynamic and boundary lubrication mechanisms. (C) 2010 Elsevier Ltd. All rights reserved.
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| 47. |
- Greene, George W., et al.
(författare)
-
Changes in pore morphology and fluid transport in compressed articular cartilage and the implications for joint lubrication
- 2008
-
Ingår i: Biomaterials. - : Elsevier BV. - 1878-5905 .- 0142-9612. ; 29:33, s. 4455-4462
-
Tidskriftsartikel (refereegranskat)abstract
- Cartilage sections were cut from the middle zone of pig knee articular cartilage and attached to substrates in two different kinds of newly designed 'pressure cells', one for fluorescence the other for NMR measurements, The fluorescence cell was filled with buffer solution containing fluorescently marked 70 kDa dextran which was allowed to diffuse into the cartilage pores. A second glass surface was then pressed down onto the thin cartilage sample under different loads (pressures), and the resulting compression (strain) and change in pore volume were measured as a function of time, simultaneously with measurements of the lateral diffusion and flow pattern of the dextran molecules using Fluorescence Recovery After Photobleaching (FRAP). Complementary experiments were made on the normal diffusion coefficients of pure electrolyte solutions (no dextran) in thicker cartilage sections with pulse-gradient NMR using a new pressure cell suitable for such measurements. Taken together our results show that the highly anisotropic structure of cartilage has a strong effect on the way fluid diffuses laterally and normally at different stages of compression. Our results also show how geometric constraints on a cartilage network and trapped high MW polymer such as HA during normal compressions are likely to affect both the normal and the lateral mobilities of polyelectrolytes and water. (C) 2008 Elsevier Ltd. All rights reserved.
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| 48. |
- Griffith, May, et al.
(författare)
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Artificial Corneas, and Reinforced Composite Implants for High Risk Donor Cornea Transplantation
- 2017
-
Ingår i: The Stem Cell Microenvironment and its Role in Regenerative Medicine and Cancer Pathogenesis. - : RIVER PUBLISHERS. - 9788793519008 - 9788793379930 ; , s. 93-102
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Konferensbidrag (refereegranskat)abstract
- Here, we review examples of artificial corneas that have been developed as alternatives to donor cornea transplantation. These consist of artificial corneas developed as prostheses and regenerative scaffolds. Examples of reinforced and composite implants developed within our group are profiled.
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| 49. |
- Grzhibovskis, Richards, 1978, et al.
(författare)
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Shape of red blood cells in contact with artificial surfaces
- 2017
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Ingår i: European Biophysics Journal. - : Springer Science and Business Media LLC. - 1432-1017 .- 0175-7571. ; 46:2, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- The phenomenon of physical contact between red blood cells and artificial surfaces is considered. A fully three-dimensional mathematical model of a bilayer membrane in contact with an artificial surface is presented. Numerical results for the different geometries and adhesion intensities are found to be in agreement with experimentally observed geometries obtained by means of digital holographic microscopy.
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| 50. |
- Gustafsson, Anna, et al.
(författare)
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The Prognostic Value of suPAR Compared to Other Inflammatory Markers in Patients with Severe Sepsis
- 2012
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Ingår i: Biomarker Insights. - : Libertas Academica. - 1177-2719 .- 1177-2719. ; :7, s. 39-44
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: It has been suggested that soluble urokinase plasminogen activator (suPAR) can be used as a marker of disease severity and risk of mortality in sepsis. The aim with the present study was to compare plasma levels of suPAR in patients with severe sepsis to control subjects and correlate it with the level of inflammatory activation, severity and mortality. Samples were collected from 27 sepsis patients at the intensive care unit (ICU), Lund, Sweden; 90-day mortalities were registered. The suPAR level was significantly elevated in sepsis patients compared to controls, but not significantly higher in nonsurvivors than survivors. Plasma levels of suPAR did correlate weakly with the SOFA score and myeloperoxidase (MPO) but not with CRP, PCT, IL-6 or IL-10 in patients with severe sepsis. The weak correlation between suPAR and other inflammatory markers might suggest that suPAR reflects general activation of the immune system rather than exerting inflammatory actions.
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