| 1. |
- Mattsson, Niklas, 1979, et al.
(författare)
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Association of brain amyloid-beta with cerebral perfusion and structure in Alzheimer's disease and mild cognitive impairment
- 2014
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 137, s. 1550-1561
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Tidskriftsartikel (refereegranskat)abstract
- Patients with Alzheimer's disease have reduced cerebral blood flow measured by arterial spin labelling magnetic resonance imaging, but it is unclear how this is related to amyloid-beta pathology. Using 182 subjects from the Alzheimer's Disease Neuroimaging Initiative we tested associations of amyloid-beta with regional cerebral blood flow in healthy controls (n = 51), early (n = 66) and late (n = 41) mild cognitive impairment, and Alzheimer's disease with dementia (n = 24). Based on the theory that Alzheimer's disease starts with amyloid-beta accumulation and progresses with symptoms and secondary pathologies in different trajectories, we tested if cerebral blood flow differed between amyloid-beta-negative controls and -positive subjects in different diagnostic groups, and if amyloid-beta had different associations with cerebral blood flow and grey matter volume. Global amyloid-beta load was measured by florbetapir positron emission tomography, and regional blood flow and volume were measured in eight a priori defined regions of interest. Cerebral blood flow was reduced in patients with dementia in most brain regions. Higher amyloid-beta load was related to lower cerebral blood flow in several regions, independent of diagnostic group. When comparing amyloid-beta-positive subjects with -negative controls, we found reductions of cerebral blood flow in several diagnostic groups, including in precuneus, entorhinal cortex and hippocampus (dementia), inferior parietal cortex (late mild cognitive impairment and dementia), and inferior temporal cortex (early and late mild cognitive impairment and dementia). The associations of amyloid-beta with cerebral blood flow and volume differed across the disease spectrum, with high amyloid-beta being associated with greater cerebral blood flow reduction in controls and greater volume reduction in late mild cognitive impairment and dementia. In addition to disease stage, amyloid-beta pathology affects cerebral blood flow across the span from controls to dementia patients. Amyloid-beta pathology has different associations with cerebral blood flow and volume, and may cause more loss of blood flow in early stages, whereas volume loss dominates in late disease stages.
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| 2. |
- Blomqvist, Per, et al.
(författare)
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Characterisation of fire generated particles : BRANDFORSK project 700-061, FireTechnology, SP Report 2010:01
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Characterisation of fire generated particlesThe present project has examined the question of distribution patterns of important chemical compounds between gas phase and particle phase. It has also, in some cases, addressed the question of the distribution of individual particle-associated species between the different size-ranges of particles produced in a fire. The chemical compounds studied were hydrogen chloride (HCl), polycyclic aromatic hydrocarbons (PAHs), and isocyanates.The steady-state tube furnace, ISO/TS 19700, was chosen as the physical fire model in order to study the production of particles from different types of fire exposure. Three different fire types were investigated: oxidative pyrolysis, well-ventilated flaming fires and vitiated post flashover. Two materials were chosen for investigation, PVC-carpet and wood board, based on their prevalence fire exposure scenarios and their chemical composition. The particle production from the two materials investigated varied both concerning the amounts produced and the particle size distributions. The production of particles on a mass basis was generally significantly lower from the wood board compared with the PVC-carpet. The tests with the PVC-carpet showed that relatively large particles are produced from all combustion conditions examined. The tests made with the wood board show preferably predisposition towards the production of small-sized particles during flaming combustion.The analysis of PAHs in the tests with the PVC-carpet showed that volatile PAHs were dominate during all types of combustion. However, when the toxicity of the individual species was taken into account, the relative importance between volatile and particle associated PAHs changed. From the tests with the wood board material (OSB) it was noted that the highest yields of total PAHs were found from under ventilated conditions, and the volatile part of the total PAH dominated for this material as well. The yields found from the well-ventilated tests were very low. Toxicity weighted data showed that the particle associated part dominated the toxicity both for under ventilated and well-ventilated conditions.A study made of the presence of chlorine on particles showed that it is clear that the major part of the HCl produced during combustion of the PVC-carpet is present in the gas phase. Chlorine was found associated with particulates but these results were, however, inconclusive due to the difficulty in determining the source of the chlorine found in the soot fractions studied.The low polyurethane (PUR) content and the substantial degradation of the PUR in the tests resulted in no or very small amounts of quantifiable isocyanate dimers (i.e. high molecular species). Monoisocyanates such as ICA and MIC dominated in the emitted degradation products. These kinds of monoisocyanates are volatile compounds and almost exclusively present in the gas phase.
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| 3. |
- De Frenne, Pieter, et al.
(författare)
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Plant movements and climate warming : intraspecific variation in growth responses to nonlocal soils
- 2014
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 202:2, s. 431-441
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Tidskriftsartikel (refereegranskat)abstract
- Most range shift predictions focus on the dispersal phase of the colonization process. Because moving populations experience increasingly dissimilar nonclimatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in nonlocal sites. We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently colder' soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate change-driven plant movements by affecting growth of nonlocal migrants, a mechanism which should be integrated into predictions of future range shifts.
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| 4. |
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| 5. |
- Rodin, S, et al.
(författare)
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Clonal culturing of human embryonic stem cells on laminin-521/E-cadherin matrix in defined and xeno-free environment
- 2014
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5, s. 3195-
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Tidskriftsartikel (refereegranskat)abstract
- Lack of robust methods for establishment and expansion of pluripotent human embryonic stem (hES) cells still hampers development of cell therapy. Laminins (LN) are a family of highly cell-type specific basement membrane proteins important for cell adhesion, differentiation, migration and phenotype stability. Here we produce and isolate a human recombinant LN-521 isoform and develop a cell culture matrix containing LN-521 and E-cadherin, which both localize to stem cell niches in vivo. This matrix allows clonal derivation, clonal survival and long-term self-renewal of hES cells under completely chemically defined and xeno-free conditions without ROCK inhibitors. Neither LN-521 nor E-cadherin alone enable clonal survival of hES cells. The LN-521/E-cadherin matrix allows hES cell line derivation from blastocyst inner cell mass and single blastomere cells without a need to destroy the embryo. This method can facilitate the generation of hES cell lines for development of different cell types for regenerative medicine purposes.
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