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| 2. |
- Andersson, Marcus, 1975, et al.
(författare)
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Quartz crystal microbalance-with dissipation monitoring (QCM-D) for real time measurements of blood coagulation density and immune complement activation on artificial surfaces
- 2005
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 0956-5663. ; 21:1, s. 79-86
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Tidskriftsartikel (refereegranskat)abstract
- A recently developed variant of quartz crystal microbalance (QCM) called QCM-with dissipation monitoring (QCM-D) allows simultaneous and simple measurements of changes in adsorbed mass as well as the viscoelastic property (D-factor) of deposited protein layers on the sensor surface. We have taken the QCM-D technology a step further and demonstrated its advantages in the study of protein assembly as a consequence of surface induced immune complement activation, or contact activated blood coagulation. In the present study we have continued our QCM-D investigations of surface assembly of fibrin clot formation and complement activation and incubated differently modified quartz sensor surfaces in blood plasma and sera. Polymer surfaces used were spin-coated polyethylene, poly(ethylene terephtalate), poly(methylmetacrylate) and poly(dimethylsiloxane). Also used were sputtered titanium and heparin grafted surfaces. In this investigation we found that we could describe the surface induced coagulation with four independent parameters: (1) Time of onset of coagulation, (2) fibrin deposition rate, (3) total frequency shift at stable plateau, and (4) fibrin clot density. The most important finding was that the blood plasma clot density can be assessed with the use of D determinations and that the clot density varied significantly with the chemical composition of the surface. However, the D-factor did not give any new analytical information about the possible complement activation mechanisms. Nevertheless, the QCM-D was found to be a reliable tool for the analysis of surface induced complement activation. We also compared the QCM-D technique with traditional enzyme immuno assay (EIA) measurements of soluble products from the surface activation of the complement and coagulation systems. We found that the results from EIA and QCM-D measurements corresponded well for the complement activation but not for the coagulation, probably due to the biological complexity of the coagulation system.
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| 4. |
- Geijer, Cecilia, 1980, et al.
(författare)
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Initiation of the transcriptional response to hyperosmotic shock correlates with the potential for volume recovery.
- 2013
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Ingår i: The FEBS journal. - : Wiley. - 1742-4658 .- 1742-464X. ; 280:16, s. 3854-67
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Tidskriftsartikel (refereegranskat)abstract
- The control of activity and localization of transcription factors is critical for appropriate transcriptional responses. In eukaryotes, signal transduction components such as mitogen-activated protein kinase (MAPK) shuttle into the nucleus to activate transcription. It is not known in detail how different amounts of nuclear MAPK over time affect the transcriptional response. In the present study, we aimed to address this issue by studying the high osmolarity glycerol (HOG) system in Saccharomyces cerevisiae. We employed a conditional osmotic system, which changes the period of the MAPK Hog1 signal independent of the initial stress level. We determined the dynamics of the Hog1 nuclear localization and cell volume by single-cell analysis in well-controlled microfluidics systems and compared the responses with the global transcriptional output of cell populations. We discovered that the onset of the initial transcriptional response correlates with the potential of cells for rapid adaptation; cells that are capable of recovering quickly initiate the transcriptional responses immediately, whereas cells that require longer time to adapt also respond later. This is reflected by Hog1 nuclear localization, Hog1 promoter association and the transcriptional response, but not Hog1 phosphorylation, suggesting that a presently uncharacterized rapid adaptive mechanism precedes the Hog1 nuclear response. Furthermore, we found that the period of Hog1 nuclear residence affects the amplitude of the transcriptional response rather than the spectrum of responsive genes.
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| 5. |
- Golpayegani, Ardeshir, 1975, et al.
(författare)
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Microstructure of a Creep-Resistant 10 Pct Chromium Steel Containing 250 ppm Boron
- 2011
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Ingår i: Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940. ; 42:4, s. 940-951
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure of a trial martensitic chromium steel containing a high content of boron (250 ppm) was characterized in detail in the as-tempered and aged conditions. This steel has a similar composition and heat treatment as the TAF steel that still is unsurpassed in creep strength among all 9 to 12 pct chromium steels. Characterization was performed by using scanning electron microscopy, energy-filtered transmission electron microscopy, secondary ion mass spectroscopy, and atom probe tomography. Focus was placed on investigating different types of precipitates that play a key role in improving the creep resistance of these steels. The low tempering temperature of 963 K (690 A degrees C) is enough for the precipitation of the full volume fraction of both MX and M23C6. A high boron content, more than 1 at. pct, was found in M23C6 precipitates and they grow slowly during aging. The high boron level in the steel results in metal borides rather than BN with the approximate formula (Mo0.66Cr0.34)(2)(Fe0.75V0.25)B-2. Two families of MX precipitates were found, one at lath boundaries about 35 nm in size and one dense inside the laths, only 5 to 15 nm in size.
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| 6. |
- Hedlund, Julia, 1975, et al.
(författare)
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Change of Colloidal and Surface Properties of Mytilus edulis Foot Protein 1 in the Presence of an Oxidation (NaIO4) or a Complex-Binding (Cu2+) Agent
- 2009
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:4, s. 845-849
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Tidskriftsartikel (refereegranskat)abstract
- Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to study the viscoelastic properties of the blue mussel, Mytilus edulis, foot protein 1 (Mefp-1) adsorbed on modified hydrophobic gold surfaces. The change in viscoelasticity was studied after addition of Cu2+ and Mn2+, which theoretically could induce metal complex formation with 3,4-dihydroxyphenylalanine (DOPA) moieties. We also used NaIO4, a nonmetal oxidative agent known to induce di-DOPA formation. Reduction in viscoelasticity of adsorbed Mefp-1 followed the order of NaIO4 > Cu2+ > buffer control > Mn2+. We also studied the formation of molecular aggregates of Mefp-1 in solution with the use of dynamic light scattering (DLS). We found that addition of Cu2+, but not Mn2+, induced the formation of larger DLS-detectable aggregates. Minor aggregate formation was found with NaIO4. With the analytical resolution of small angle X-ray scattering (SAXS), we could detect differences in the molecular structure between NaIO4- and Cu2+-treated Mefp-1 aggregates. We concluded from this study that Cu2+ could participate in intermolecular cross-linking of the Mefp-1 molecule via metal complex formation. Metal incorporation in the protein most likely increases the abrasion resistance of the Mefp-1 layer. NaIO4, on the other hand, resulted in mainly intramolecular formation of di-DOPA, but failed to induce larger intermolecular aggregation phenomena. The described methodological combination of surface sensitive methods, like QCM-D, and bulk sensitive methods, like DLS and SAXS, generates high resolution results and is an attractive platform to investigate intra- and intermolecular aspects of assembly and cross-linking of the Mefp proteins.
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| 7. |
- Andersson, Johan, et al.
(författare)
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Response surface methods and pareto optimization in crashworthiness design
- 2003
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Ingår i: Proceedings of Design Engineering Technical Conferences and Computers and Information in Engineering Conference/Design Automation Conference. - Chicago, USA : ASME. - 0791837009 ; , s. 473-479
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Konferensbidrag (refereegranskat)abstract
- This paper presents a method where a multi objective optimization techniqueis used together with response surface methods in order to support crashworthiness design. As in most engineering design problems thereare several conflicting objectives that have to be considered when formulating a design problem as an optimization problem. Here this is exemplified by the desire to minimize the intrusion into the passenger compartment area and simultaneously obtain low maximum acceleration during vehicle impact. These two objectives are naturally conflicting, since low maximum acceleration implies large intrusion. The contribution of thispaper is to show a successful application of a set of existing methods to solve a real world engineering problem.The paper also presents methods of illustrating the results obtained from the multi-objective optimization.
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| 8. |
- Andersson, Linda, 1973, et al.
(författare)
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Deficiency in perilipin 5 reduces mitochondrial function and membrane depolarization in mouse hearts.
- 2017
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Ingår i: The international journal of biochemistry & cell biology. - : Elsevier BV. - 1878-5875 .- 1357-2725. ; 91:Pt A, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- Myocardial triglycerides stored in lipid droplets are important in regulating the intracellular delivery of fatty acids for energy generation in mitochondria, for membrane biosynthesis, and as agonists for intracellular signaling. Previously, we showed that deficiency in the lipid droplet protein perilipin 5 (Plin5) markedly reduces triglyceride storage in cardiomyocytes and increases the flux of fatty acids into phospholipids. Here, we investigated whether Plin5 deficiency in cardiomyocytes alters mitochondrial function. We found that Plin5 deficiency reduced mitochondrial oxidative capacity. Furthermore, in mitochondria from Plin5((-/)(-)) hearts, the fatty acyl composition of phospholipids in mitochondrial membranes was altered and mitochondrial membrane depolarization was markedly compromised. These findings suggest that mitochondria isolated from hearts deficient in Plin5, have specific functional defects.
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| 9. |
- Andersson, Linda, 1973, et al.
(författare)
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Glucosylceramide synthase deficiency in the heart compromises β1-adrenergic receptor trafficking
- 2021
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 42:43, s. 4481-4492
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Cardiac injury and remodelling are associated with the rearrangement of cardiac lipids. Glycosphingolipids are membrane lipids that are important for cellular structure and function, and cardiac dysfunction is a characteristic of rare monogenic diseases with defects in glycosphingolipid synthesis and turnover. However, it is not known how cardiac glycosphingolipids regulate cellular processes in the heart. The aim of this study is to determine the role of cardiac glycosphingolipids in heart function.METHODS AND RESULTS: Using human myocardial biopsies, we showed that the glycosphingolipids glucosylceramide and lactosylceramide are present at very low levels in non-ischaemic human heart with normal function and are elevated during remodelling. Similar results were observed in mouse models of cardiac remodelling. We also generated mice with cardiomyocyte-specific deficiency in Ugcg, the gene encoding glucosylceramide synthase (hUgcg-/- mice). In 9- to 10-week-old hUgcg-/- mice, contractile capacity in response to dobutamine stress was reduced. Older hUgcg-/- mice developed severe heart failure and left ventricular dilatation even under baseline conditions and died prematurely. Using RNA-seq and cell culture models, we showed defective endolysosomal retrograde trafficking and autophagy in Ugcg-deficient cardiomyocytes. We also showed that responsiveness to β-adrenergic stimulation was reduced in cardiomyocytes from hUgcg-/- mice and that Ugcg knockdown suppressed the internalization and trafficking of β1-adrenergic receptors.CONCLUSIONS: Our findings suggest that cardiac glycosphingolipids are required to maintain β-adrenergic signalling and contractile capacity in cardiomyocytes and to preserve normal heart function.
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