| 1. |
- Hook, F.F, et al.
(author)
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A comparative study of protein adsorption on titanium oxide surfaces using in situ ellipsometry, optical waveguide lightmode spectroscopy, and quartz crystal microbalance/dissipation
- 2002
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In: Colloids and Surfaces B. - 0927-7765 .- 1873-4367. ; 24:2, s. 155-170
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Journal article (peer-reviewed)abstract
- The adsorption kinetics of three model proteins - human serum albumin, fibrinogen and hemoglobin - has been measured and compared using three different experimental techniques: optical waveguide lightmode spectroscopy (OWLS), ellipsometry (ELM) and quartz crystal microbalance (QCM-D). The studies were complemented by also monitoring the corresponding antibody interactions with the pre-adsorbed protein layer. All measurements were performed with identically prepared titanium oxide coated substrates. All three techniques are suitable to follow in-situ kinetics of protein-surface and protein-antibody interactions, and provide quantitative values of the adsorbed adlayer mass. The results have, however, different physical contents. The optical techniques OWLS and ELM provide in most cases consistent and comparable results, which can be straightforwardly converted to adsorbed protein molar ('dry') mass. QCM-D, on the other hand, produces measured values that are generally higher in terms of mass. This, in turn, provides valuable, complementary information in two respects: (i) the mass calculated from the resonance frequency shift includes both protein mass and water that binds or hydrodynamically couples to the protein adlayer, and (ii) analysis of the energy dissipation in the adlayer and its magnitude in relation to the frequency shift (c.f. adsorbed mass) provides insight about the mechanical/structural properties such as viscoelasticity. © 2002 Elsevier Science B.V. All rights reserved.
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| 2. |
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| 3. |
- Brownlie, D, et al.
(author)
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Comparison of Lung-Homing Receptor Expression and Activation Profiles on NK Cell and T Cell Subsets in COVID-19 and Influenza
- 2022
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In: Frontiers in immunology. - : Frontiers Media SA. - 1664-3224. ; 13, s. 834862-
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Journal article (peer-reviewed)abstract
- Respiratory viral infections with SARS-CoV-2 and influenza viruses commonly induce a strong infiltration of immune cells into the human lung, with potential detrimental effects on the integrity of the lung tissue. Despite comprising the largest fractions of circulating lymphocytes in the lung, rather little is known about how peripheral blood natural killer (NK) cell and T cell subsets are equipped for lung-homing in COVID-19 and influenza. Here, we provide a detailed comparative analysis of NK cells and T cells in patients infected with SARS-CoV-2 or influenza virus, focusing on the protein and gene expression of chemokine receptors known to be involved in recruitment to the lung. For this, we used 28-colour flow cytometry as well as re-analysis of a publicly available single-cell RNA-seq dataset from bronchoalveolar lavage (BAL) fluid. Frequencies of NK cells and T cells expressing CXCR3, CXCR6, and CCR5 were altered in peripheral blood of COVID-19 and influenza patients, in line with increased transcript expression of CXCR3, CXCR6, and CCR5 and their respective ligands in BAL fluid. NK cells and T cells expressing lung-homing receptors displayed stronger phenotypic signs of activation compared to cells lacking lung-homing receptors, and activation was overall stronger in influenza compared to COVID-19. Together, our results indicate a role for CXCR3+, CXCR6+, and/or CCR5+ NK cells and T cells that potentially migrate to the lungs in moderate COVID-19 and influenza patients, identifying common targets for future therapeutic interventions in respiratory viral infections.
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| 4. |
- Edvardsson, Malin, 1973, et al.
(author)
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Investigation of binding event perturbations caused by elevated QCM-D oscillation amplitude
- 2006
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In: Analyst. - : Royal Society of Chemistry (RSC). - 1364-5528. ; 131:7, s. 822-828
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Journal article (peer-reviewed)abstract
- We report measurements with the quartz crystal microbalance with dissipation monitoring (QCM-D) technique, with focus on how the shear oscillation amplitude of the sensor surface influences biorecognition binding events. Technically, this is made as reported recently ( M. Edvardsson, M. Rodahl, B. Kasemo, F. Hook, Anal. Chem., 2005, 77( 15), 4918-4926) by operating the QCM in dual frequency mode; one harmonic (n = n(1)) is utilized for continuous excitation of the QCM-D sensor at resonance at variable driving amplitudes (1-10 V), while the second harmonic (n not equal n(1)) is used for combined f and D measurements. By using one harmonic as a "probe" and the other one as an "actuator", elevated amplitudes can be used to perturb - or activate - binding reactions in a controlled way, while simultaneously maintaining the possibility of probing the adsorption and/or desorption events in a non-perturbative manner using combined f and D measurements. In this work we investigate the influence of oscillation amplitude variations on the binding of NeutrAvidin-modified polystyrene beads (O similar to 200 nm) to a planar biotin-modified lipid bilayer supported on an SiO2-modified QCM-D sensor. These results are further compared with data on an identical system, except that the NeutrAvidin-biotin recognition was replaced by fully complementary DNA hybridization. Supported by micrographs of the binding pattern, the results demonstrate that there exists, for both systems, a unique critical oscillation amplitude, A(c), below which binding is unaffected by the oscillation, and above which binding is efficiently prevented. Associated with A(c), there is a critical crystal radius, r(c), defining the central part of the crystal where binding is prevented. From QCM-D data, A(c) for the present system was estimated to be similar to 6.5 nm, yielding a value of r(c) of similar to 3 mm - the latter number was nicely confirmed by fluorescent- and dark-field micrographs of the crystal. Furthermore, the fact that A(c) is observed to be identical for the two types of biorecognition reactions suggests that it is neither the strength, nor the number of contact points, that determine the amplitude at which binding is prevented. Rather, particle size seems to be the determining parameter.
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| 5. |
- Larsson Wexell, Cecilia, 1965, et al.
(author)
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Bone response to surface modified titanium implants: studies on electropolished implants with different oxide thicknesses and morphology.
- 1994
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In: Biomaterials. - 0142-9612. ; 15:13, s. 1062-74
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Journal article (peer-reviewed)abstract
- In a series of experimental studies, bone formation was analysed around systematically modified titanium implants. In the present study, machined, electropolished and anodically oxidized implants were prepared, surface characterized and inserted in the cortical bone of rabbits (7 wks and 12 wks). SEM, scanning Auger electron spectroscopy and atomic force microscopy revealed no differences in surface composition but marked differences in oxide thickness, surface topography and roughness. Light microscopic morphology and morphometry showed that all implants were in contact with bone, and had a large proportion of bone within the threads. The smooth, electropolished implants were surrounded by less bone than the machined implants with similar oxide thickness, (4-5 nm) and the anodically oxidized implants with thicker oxides (21 nm and 180 nm, respectively) after 7 wks. These studies show that a high degree of bone contact and bone formation can be achieved with titanium implants which are modified with respect to oxide thickness and surface topography. However, it appears that a reduction of surface roughness may influence the rate of bone formation in rabbit cortical bone.
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| 6. |
- Larsson Wexell, Cecilia, 1965, et al.
(author)
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Bone response to surface-modified titanium implants: studies on the early tissue response to machined and electropolished implants with different oxide thicknesses.
- 1996
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In: Biomaterials. - 0142-9612. ; 17:6, s. 605-16
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Journal article (peer-reviewed)abstract
- The bone formation around titanium implants with varied surface properties is investigated. Machined and electropolished samples with and without thick, anodically formed surface oxides were prepared, surface characterized and inserted in the cortical bone of rabbits (1, 3 and 6 weeks). Scanning electron microscopy, scanning Auger electron spectroscopy and atomic force microscopy revealed marked differences in oxide thickness, surface topography and roughness, but no significant differences in surface chemical composition, between the different groups of implants. Light microscopic morphology and morphometry showed that all implants were in contact with bone and had a large proportion of bone within the threads at 6 weeks. The smooth, electropolished implants, irrespective of anodic oxidation, were surrounded by less bone than the machined implants after 1 week. After 6 weeks the bone volume as well as the bone-implant contact were lower for the merely electropolished implants than for the other three groups. Our study shows that a high degree of bone contact and bone formation are achieved with titanium implants which are modified with respect to oxide thickness and surface topography. However, the result with the smooth (electropolished) implants indicates that a reduction of surface roughness, in the initial phase, decreases the rate of bone formation in rabbit cortical bone.
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| 7. |
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| 8. |
- Olin, Håkan, et al.
(author)
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Scanning tunneling microscopy of oxidized titanium surfaces in air
- 1992
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In: Ultramicroscopy. - 0304-3991 .- 1879-2723. ; 42:Part A, s. 567-571
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Journal article (peer-reviewed)abstract
- Using an STM in air, we have studied three different electropolished Ti surfaces. One sample was analyzed without further treatment. The second was thermally oxidized in air at 500-degrees-C. The third was exposed to an argon glow discharge and then oxidized in pure oxygen. The samples were characterized by Auger spectroscopy prior to STM measurements. Electropolished and thermally oxidized samples showed a granular structure, with a low corrugation between 2 and 10 nm. At a larger scale, the glow discharge treated sample showed a high corrugation approximately 100 nm.
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| 9. |
- Rusten, Tor Erik, et al.
(author)
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Fab1 phosphatidylinositol 3-phosphate 5-kinase controls trafficking but not silencing of endocytosed receptors.
- 2006
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In: Molecular Biology of the Cell. - 1059-1524 .- 1939-4586. ; 17:9, s. 3989-4001
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Journal article (peer-reviewed)abstract
- The trafficking of endocytosed receptors through phosphatidylinositol 3-phosphate [PtdIns(3)P]-containing endosomes is thought to attenuate their signaling. Here, we show that the PtdIns(3)P 5-kinase Fab1/PIKfyve controls trafficking but not silencing of endocytosed receptors. Drosophila fab1 mutants contain undetectable phosphatidylinositol 3,5-bisphosphate levels, show profound increases in cell and organ size, and die at the pupal stage. Mutant larvae contain highly enlarged multivesicular bodies and late endosomes that are inefficiently acidified. Clones of fab1 mutant cells accumulate Wingless and Notch, similarly to cells lacking Hrs, Vps25, and Tsg101, components of the endosomal sorting machinery for ubiquitinated membrane proteins. However, whereas hrs, vps25, and tsg101 mutant cell clones accumulate ubiquitinated cargo, this is not the case with fab1 mutants. Even though endocytic receptor trafficking is impaired in fab1 mutants, Notch, Wingless, and Dpp signaling is unaffected. We conclude that Fab1, despite its importance for endosomal functions, is not required for receptor silencing. This is consistent with the possibility that Fab1 functions at a late stage in endocytic receptor trafficking, at a point when signal termination has occurred.
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