| 1. |
- Schanzenbach, Christoph, et al.
(författare)
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Preparation and characterisation of a sensing system for wireless pH measurements in vivo, in a rumen of a cow
- 2017
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 242, s. 637-644
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Tidskriftsartikel (refereegranskat)abstract
- We describe a sensing system that is able to measure pH in-vivo, in the rumen of a cow, in real time. The sensing principle is based on gravimetric transduction using a magnetoelastic ribbon functionalized by pH-sensitive nanobeads that is placed in the rumen where it is actuated and read-out wirelessly. We describe a generic procedure that enables one to deposit monolayers or multilayers of nano- and micro beads onto virtually any substrate. The topography of the resulting layers as well as interlayer coverages were characterised using optical microscopy and scanning profilometry. First we determined performance of the system in-vitro, in phosphate-buffered saline, in McDougall's buffer and in a rumen fluid. Thereafter we also performed in-vivo measurements. Using buffers we determined pH response in the liquids both at the fundamental frequency of the functionalised foils, and at the 1st overtone. We argue that observed frequency changes vs pH are mainly due to changes of trapped liquid when the bead layers shrink or expand as a response to changed pH. The data obtained from the pH response of magnetoelastic foils at different bead coverages was modelled by a simple two-parameter model that corroborates this assumption.
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| 2. |
- Solé-Domènech, Santiago, et al.
(författare)
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Localization of cholesterol, amyloid and glia in Alzheimer's disease transgenic mouse brain tissue using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and immunofluorescence imaging
- 2013
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Ingår i: Acta Neuropathologica. - : Springer Science and Business Media LLC. - 0001-6322 .- 1432-0533. ; 125:1, s. 145-157
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Tidskriftsartikel (refereegranskat)abstract
- The spatial distributions of lipids, amyloid-beta deposits, markers of neurons and glial cells were imaged, at submicrometer lateral resolution, in brain structures of a mouse model of Alzheimer's disease using a new methodology that combines time-of-flight secondary ion mass spectrometry (ToF-SIMS) and confocal fluorescence microscopy. The technology, which enabled us to simultaneously image the lipid and glial cell distributions in Tg2576 mouse brain structures, revealed micrometer-sized cholesterol accumulations in hippocampal regions undergoing amyloid-beta deposition. Such cholesterol granules were either associated with individual amyloid deposits or spread over entire regions undergoing amyloidogenesis. Subsequent immunohistochemical analysis of the same brain regions showed increased microglial and astrocytic immunoreactivity associated with the amyloid deposits, as expected from previous studies, but did not reveal any particular astrocytic or microglial feature correlated with cholesterol granulation. However, dystrophic neurites as well as presynaptic vesicles presented a distribution similar to that of cholesterol granules in regions undergoing amyloid-beta accumulation, thus indicating that these neuronal endpoints may retain cholesterol in areas with lesions. In conclusion, the present study provides evidence for an altered cholesterol distribution near amyloid deposits that would have been missed by several other lipid analysis methods, and opens for the possibility to study in detail the putative liaison between lipid environment and protein structure and function in Alzheimer's disease.
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