| 1. |
- Lindgren, Johan, et al.
(författare)
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Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur
- 2018
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 564:7736
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Tidskriftsartikel (refereegranskat)abstract
- Ichthyosaurs are extinct marine reptiles that display a notable external similarity to modern toothed whales. Here we show that this resemblance is more than skin deep. We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius. Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers. These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy. Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment. Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation. Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.
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| 2. |
- Arvidsson, Anna, 1973, et al.
(författare)
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Early interactions between leukocytes and three different potentially bioactive titanium surface modifications
- 2011
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 97:2, s. 364-72
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to compare the early interactions between leukocytes and three different surface modifications, suggested as bioactive. Blasted titanium discs were modified by alkali and heat treatment, sodium fluoride treatment, or hydroxyapatite coating. A number of these discs were also immersed in simulated body fluid (SBF) for a week, a treatment which yielded high levels of calcium and phosphate on each surface type. The specimens were exposed for human venous blood for 32 minutes and the respiratory burst response was measured in terms of reactive oxygen species with a luminometer, and coverage of viable cells with a fluorescence microscope after staining steps. The topography, morphology, and chemistry of the surfaces were evaluated with optical interferometry and scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). A high respiratory burst response was found for HA coated titanium in comparison with the other surface groups (p < 0.0005). The SBF immersion resulted in an increased respiratory burst response (p < 0.0005) and removed statistically significant differences between the surface groups. Thus, the results in the present study indicate that different titanium surface modifications influence the early inflammatory response differently, and that calcium phosphate compounds increase the inflammatory response.
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| 3. |
- Bastos, Carlos A.P., et al.
(författare)
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Copper nanoparticles have negligible direct antibacterial impact
- 2020
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Ingår i: NanoImpact. - : Elsevier BV. - 2452-0748. ; 17
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Soluble copper that can be acquired by bacteria is toxic and therefore antimicrobial. Whether nanostructured copper materials, in either disperse or agglomerated form, have antimicrobial impact, aside from that of their dissolution products, is not clear and was herein addressed. Methods: We took five nanostructured copper materials, two metallic, and three oxo-hydroxides with one of these being silicate-substituted. Four agglomerated in the bacterial growth media whilst the silicate-substituted material remained disperse and small (6.5 nm diameter). Antibacterial activity against E. coli was assessed with copper phase distribution measured over time. Using the dose of soluble copper, and benchmark dose non-linear regression modelling, we determined how well this phase predicted antimicrobial activity. Finally, we used Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) analysis to investigate whether membrane adhe- sion effects by copper were plausible or if intracellular uptake most likely explained the bacterial impact of copper. Results: Comparison over time of antimicrobial activity against particulate or soluble phases of the aquated materials clearly demonstrated that soluble copper but not particulate forms were associated with inhibition of bacterial growth. Indeed, the benchmark dose modelling showed the soluble dose required to cause a 50% reduction in E. coli growth was strongly clustered – for all particle formulations – at 14.5 mg/L (10–19 mg/L 90% confidence interval). By comparison, total copper levels associated with the same reduction in viability varied widely (45–549 mg/L). Finally, in favour of this soluble product dominance in terms of antimicrobial activity, copper had low association with bacterial membrane (something both soluble and particulate materials could do) but showed high intra-bacterial levels (something only soluble copper could do). Conclusion: Taken together our data show that it is the uptake of soluble but not particulate copper, and the intracellular loading not just contact and membrane association, that drives copper toxicity to bacteria. Therapeutic strategies for novel antimicrobial copper compounds should consider these findings.
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| 4. |
- Johansson, Jakob, et al.
(författare)
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On the function of lead (Pb) in machining brass alloys
- 2022
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 120:11-12, s. 7263-7275
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Tidskriftsartikel (refereegranskat)abstract
- Lead has traditionally been added to brass alloys to achieve high machinability, but the exact mechanisms at work are still debated. Lead-free brass alternatives could be developed if these mechanisms were better understood. Accordingly, machinability characteristics were investigated for two brass alloys with similar mechanical properties and phase composition, but with very different machining characteristics because one has 3 wt.% lead (CuZn38Pb3) while the other has only 0.1 wt.% (CuZn42). The effect of the lead was investigated using infrared temperature measurement, electron microscopy, secondary ion mass spectroscopy, quick-stop methods, and high-speed filming. Neither melting of lead nor its deposition on the tool rake surface takes place during machining thus confirming its limited lubrication and tribological effects. Instead, the main role of lead is to promote discontinuous chip formation. Lead deforms to flake-like shapes that act as crack initiation points when the workpiece material passes through the primary deformation zone. This effect prevents the development of stable tool–chip contact, thus lowering cutting forces, friction, and process temperature.
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| 5. |
- Malmberg, Per, 1974, et al.
(författare)
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Formation of hydroxyapatite on titanium implants in vivo precedes bone-formation during healing
- 2017
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Ingår i: Biointerphases. - : American Vacuum Society. - 1934-8630 .- 1559-4106. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- The bone material interface has been an area of intense study over many decades, where studies of the healing process ranging from simple mineral deposition in vitro to actual healing in vivo have given important clues to the importance of calcium minerals in the bone/implant interface. Here, the authors use a combination of in vitro cell culture methods and in vivo implantation to study how the role of the spontaneously formed hydroxyapatite layer on Ti-implants for the in vivo-healing into the bone tissue of rat tibia. Initial experiments were made in reduced systems by incubation of TiO2 in cell culture medium and analysis by time of flight secondary ion mass spectrometry (ToF-SIMS) and energy-dispersive x-ray spectroscopy followed by subsequent exposure of human embryological stem cells analyzed by von Kossa staining and environmental scanning electron microsopy. In vivo studies of the bone-material interface was analyzed by ToF-SIMS depth profiling using both C-60(+) ions as well as a gas cluster ion source beam, Ar-1500(+) as sputter source. The low ion yield of the Ar-1500(+) for inorganics allowed the inorganic/organic interface of the implant to be studied avoiding the erosion of the inorganic materials caused by the conventional C-60(+) beam. (C) 2017 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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| 6. |
- Malmberg, Per, 1974, et al.
(författare)
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Imaging mass spectrometry for novel insights into contact allergy - a proof-of-concept study on nickel
- 2018
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Ingår i: Contact Dermatitis. - : Wiley. - 0105-1873 .- 1600-0536. ; 78:2, s. 109-116
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Tidskriftsartikel (refereegranskat)abstract
- Background. In spite of extensive regulation to limit exposure, nickel remains the main cause of contact allergy in the general population. More detailed knowledge on the skin uptake of haptens is required. So far, no method exists for the visualization of this clinically relevant hapten and its distribution in the skin. Objectives. To show, in terms of a proof of concept, that imaging mass spectrometry [time of flight secondary ion mass spectrometry (ToF-SIMS)] can be applied for investigation of the penetration and distribution of nickel in human skin. Method. Full-thickness human skin obtained from breast reduction surgery was exposed to nickel sulfate (5% in deionized water) for 24 h in Franz-type diffusion cells. Biopsies were obtained from nickel-treated samples and control (deionized water). The tissue was sliced, and analysed with ToF-SIMS, generating high-resolution images of ion distribution in the epidermis and upper dermis. Results. The skin layers could be discerned from the ToF-SIMS data, particularly on the basis of the collagen signal. Nickel ions were localized to the stratum corneum and upper epidermis. Conclusions. This is the first time that ToF-SIMS has been applied to trace the distribution of a hapten in human skin. Proof of principle was shown for nickel, and the technique can, in the future, be expanded for investigation of the skin distribution of clinically relevant sensitizers in general.
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| 7. |
- Nygren, Håkan, 1952, et al.
(författare)
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Mg-corrosion, hydroxyapatite, and bone healing
- 2017
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Ingår i: Biointerphases. - : American Vacuum Society. - 1934-8630 .- 1559-4106. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- The different capacities of magnesium in the metallic form (Mg-metal) and magnesium oxide (MgO) to stimulate bone healing are possible clues in the search for products that may promote bone healing. Since both Mg-metal and MgO can be assumed to release comparable amounts of Mg2+ ions during their reactions in the tissue where they have been implanted, it is of some importance to follow this process and analyze the resulting mineral formation in the tissue at the implantation site. Implants of MgO were inserted into rat tibia, and the bone healing was compared with sham-operated controls. Samples were taken after 1 week of healing and analyzed by histology, environmental scanning electron microscopy equipped with an energy dispersive x-ray spectroscopy analyzer, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Callus bone was seen in sham-operated controls after 1 week of healing. Implantation of MgO impaired the callus bone formation by replacing bone with apparently mineralized areas, lacking osteocytes and were denoted, amorphous bodies. Elemental analysis showed increased levels of Ca (7.1%), P (3.7%), and Mg (0.2%) in the bone marrow of MgO-treated animals versus sham-operated controls Ca (2.4%), P (2.3%), and Mg (0.1%). The Ca content of the cortical bone was also significantly increased (Ca, 29% increase) in MgO-treated animals compared to sham-operated controls. The Ca content of the cortical bone of sham-operated animals was also significantly (p < 0.05) higher than the corresponding value of untreated animals, which means that the surgical trauma induces an altered composition of the bone mineral. The Ca/P ratio was 1.26-1.68, which is compatible with that of mineralized bone with different contents of organic materials. Analysis of bone sections using ToF-SIMS showed the presence of hydroxyapatite (HA) and MgCO3 in the bone marrow and in cortical bone. Analysis using x-ray photoelectron spectroscopy of Mg, MgO, and MgCO3 after incubation with cell culture medium (DMEM), in vitro, showed binding of CaPO4 at the Mg and MgO samples. The Ca/P ratio was 0.8, indicating a higher P content than that expected for HA. Exposure of human embryonic stem cells to Mg species preincubated in DMEM resulted in HA production by the cells. Thus, two sources of CaPO4 in the bone marrow of MgO-treated bone were defined, catalytic formation on Mg-species and synthesis from activated stem-cells. The presented data suggest that bone healing near Mg implants is congruent with the fracture healing of bone, boosted by high HA levels in the bone marrow. In this context, the different capacities of Mg-metal and MgO to catalyse the formation of HA can be important clues to their different bone promoting effects. (C) 2017 Author(s).
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| 8. |
- Agarwal, Nisha Rani, 1987, et al.
(författare)
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Investigation of psoriasis skin tissue by label-free multi-modal imaging: a case study on a phototherapy-treated patient
- 2019
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Ingår i: Psoriasis: Targets and Therapy. - 2230-326X. ; 9, s. 43-57
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Tidskriftsartikel (refereegranskat)abstract
- Background: Psoriasis is a systemic inflammatory disease characterized by epidermal proliferation in the skin. Altered lipid metabolism is considered to be a central factor in the psoriatic etiopathogenesis. Thus, it is necessary to visualize chemical specificity of the samples for better medical diagnosis and treatment. Here, we investigate its role in the development of psoriatic lesions, before and after ultraviolet phototherapy, in a case study. Methods: The distribution and morphology of different lipids and fibrous proteins in psoriatic (lesional) tissues were visualized by two complementary label-free imaging techniques: 1) non-linear microscopy (NLM), providing images of lipids/proteins throughout the skin layers at submicrometer resolution; and 2) mass spectrometry imaging (MSI), offering high chemical specificity and hence the detection of different lipid species in the epidermal and dermal regions. A conventional method of histological evaluation was performed on the tissues, with no direct comparison with NLM and MSI. Results: Psoriatic tissues had a higher lipid content, mainly in cholesterol, in both the epidermal and dermal regions, compared to healthy tissues. Moreover, the collagen and elastin fibers in the psoriatic tissues had a tendency to assemble as larger bundles, while healthy tissues showed smaller fibers more homogeneously spread. Although phototherapy significantly reduced the cholesterol content, it also increased the amounts of collagen in both lesional and non-lesional tissues. Conclusion: This study introduces NLM and MSI as two complementary techniques which are chemical specific and can be used to assess and visualize the distribution of lipids, collagen, and elastin in a non-invasive and label-free manner.
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| 9. |
- Amombo Noa, Francoise Mystere, 1988, et al.
(författare)
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Metal-Organic Frameworks with Hexakis(4-carboxyphenyl)benzene: Extensions to Reticular Chemistry and Introducing Foldable Nets
- 2020
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 142:20, s. 9471-9481
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Tidskriftsartikel (refereegranskat)abstract
- Nine metal-organic frameworks have been prepared with the hexagon-shaped linker 1,2,3,4,5,6-hexakis(4-carboxyphenyl)-benzene (H(6)cpb) by solvothermal reactions in dimethylformamide (dmf) or dimethylacetamide (dmac) with acetic acid or formic acid as modulators: [Bi-2(cpb)(acetato)(2)(dmf)(2)]center dot 2dmf CTH-6 forms a rtl-net; 2(H2NMe2)[Cu-2(cpb)] CTH-7 forms a kgd-net; [Fe-4(cpb)-(acetato)(2)(dmf)(4)] CTH-8 and [Co-4(cpb)(acetato)(2)(dmf)(4)] CTH-9 are isostructural and form yav-nets; 2(HNEt3)[Fe-2(cpb)] CTH-10 and the two polymorphs of 2(H2NMe2)[Zn-2(cpb)]center dot 1.5dmac, Zn-MOF-888 and CTH-11, show kgd-nets; [Cu-2(cpb)-(acetato)(2)(dmf)(2)]center dot 2dmf, CTH-12, forms a mixed coordination and hydrogen-bonded sql-net; and 2(H2NMe2)[Zn-2(cpb)] CTH-13, a similarly mixed yav-net. Surface area values (Brunauer-Emmett-Teller, BET) range from 34 m(2) g(-1) for CTH-12 to 303 m(2) g(-1) for CTH-9 for samples activated at 120 degrees C in dynamic vacuum. All compounds show normal (10-fold higher) molar CO2 versus N-2 uptake at 298 K, except the 19-fold CO2 uptake for CTH-12 containing Cu(II) dinuclear paddle-wheels. We also show how perfect hexagons and triangles can combine to a new 3D topology laf, a model of which gave us the idea of foldable network topologies, as the laf-net can fold into a 2D form while retaining the local geometry around each vertex. Other foldable nets identified are cds, cds-a, ths, sqc163, clh, jem, and tfc covering the basic polygons and their combinations. The impact of this concept on "breathing" MOFs is discussed. I-2 sorption, both from gas phase and from MeOH solution, into CTH-7 were studied by time of flight secondary ion mass spectrometry (ToF-SIMS) on dried crystals. I-2 was shown to have penetrated the crystals, as layers were consecutively peeled off by the ion beam. We suggest ToF-SIMS to be a method for studying sorption depth profiles of MOFs.
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| 10. |
- Angerer, Tina B., 1987, et al.
(författare)
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Improved Molecular Imaging in Rodent Brain with Time-of-Flight-Secondary Ion Mass Spectrometry Using Gas Cluster Ion Beams and Reactive Vapor Exposure
- 2015
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 87:8, s. 4305-4313
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Tidskriftsartikel (refereegranskat)abstract
- Imaging mass spectrometry has shown to be a valuable method in medical research and can be performed using different instrumentation and sample preparation methods, each one with specific advantages and drawbacks. Time-of-flight-secondary ion mass spectrometry (TOF-SIMS) has the advantage of high spatial resolution imaging but is often restricted to low mass molecular signals and can be very sensitive to sample preparation artifacts. In this report we demonstrate the advantages of using gas cluster ion beams (GCIBs) in combination with trifluoracetic acid (TFA) vapor exposure for the imaging of lipids in mouse brain sections. There is an optimum exposure to TFA that is beneficial for increasing high mass signal as well as producing signal from previously unobserved species in the mass spectrum. Cholesterol enrichment and crystallization on the sample surface is removed by TFA exposure uncovering a wider range of lipid species in the white matter regions of the tissue, greatly expanding the chemical coverage and the potential application of TOF-SIMS imaging in neurological studies. Ar-4000(+) (40 keV) in combination with TFA treatment facilitates high resolution, high mass imaging closing the gap between TOF-SIMS and matrix-assisted laser desorption ionization (MALDI).
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