| 11. |
- Ekblad, Alf, 1957-, et al.
(författare)
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The production and turnover of extramatrical mycelium of ectomycorrhizal fungi in forest soils : role in carbon cycling
- 2013
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 366:1-2, s. 1-27
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Forskningsöversikt (refereegranskat)abstract
- There is growing evidence of the importance of extramatrical mycelium (EMM) of mycorrhizal fungi in carbon (C) cycling in ecosystems. However, our understanding has until recently been mainly based on laboratory experiments, and knowledge of such basic parameters as variations in mycelial production, standing biomass and turnover as well as the regulatory mechanisms behind such variations in forest soils is limited. Presently, the production of EMM by ectomycorrhizal (EM) fungi has been estimated at similar to 140 different forest sites to be up to several hundreds of kg per ha per year, but the published data are biased towards Picea abies in Scandinavia. Little is known about the standing biomass and turnover of EMM in other systems, and its influence on the C stored or lost from soils. Here, focussing on ectomycorrhizas, we discuss the factors that regulate the production and turnover of EMM and its role in soil C dynamics, identifying important gaps in this knowledge. C availability seems to be the key factor determining EMM production and possibly its standing biomass in forests but direct effects of mineral nutrient availability on the EMM can be important. There is great uncertainty about the rate of turnover of EMM. There is increasing evidence that residues of EM fungi play a major role in the formation of stable N and C in SOM, which highlights the need to include mycorrhizal effects in models of global soil C stores.
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| 12. |
- Ekblad, Laura L., et al.
(författare)
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Midlife insulin resistance, APOE genotype, and late-life brain amyloid accumulation
- 2018
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Ingår i: Neurology. - : Lippincott Williams & Wilkins. - 0028-3878 .- 1526-632X. ; 90:13, s. e1150-e1157
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Tidskriftsartikel (refereegranskat)abstract
- Objective To examine whether midlife insulin resistance is an independent risk factor for brain amyloid accumulation in vivo after 15 years, and whether this risk is modulated by APOE epsilon 4 genotype. Methods This observational study examined 60 elderly volunteers without dementia (mean age at baseline 55.4 and at follow-up 70.9 years, 55.5% women) from the Finnish population-based, nationwide Health2000 study with [C-11]Pittsburgh compound B-PET imaging in 2014-2016. The participants were recruited according to their homeostatic model assessment of insulin resistance (HOMA-IR) values in the year 2000, and their APOE epsilon 4 genotype. The exposure group (IR+, n = 30) consisted of individuals with HOMA-IR > 2.17 at baseline (highest tertile of the Health2000 study population), and the control group (IR-, n = 30) consisted of individuals with HOMA-IR < 1.25 at baseline (lowest tertile). The groups were enriched for APOE epsilon 4 carriers, resulting in 50% (n = 15) APOE epsilon 4 carriers in both groups. Analyses were performed with multivariate logistic and linear regression. Results An amyloid-positive PET scan was found in 33.3% of the IR-group and 60.0% of the IR+ group (odds ratio 3.0, 95% confidence interval 1.1-8.9, p = 0.04). The increased risk was seen in carriers and noncarriers of APOE epsilon 4 genotype. Higher midlife, but not late-life continuous HOMA-IR was associated with a greater brain amyloid burden at follow-up after multivariate adjustments for other cognitive and metabolic risk factors (ss = 0.11, 95% confidence interval 0.002-0.22, p = 0.04). Conclusions These results indicate that midlife insulin resistance is an independent risk factor for brain amyloid accumulation in elderly individuals without dementia.
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| 13. |
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| 14. |
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| 15. |
- Ekblad, Tobias, 1979-, et al.
(författare)
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Patterned Hydrogels for Controlled Platelet Adhesion from Whole Blood and Plasma
- 2010
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Ingår i: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 20:15, s. 2396-2403
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Tidskriftsartikel (refereegranskat)abstract
- This work describes the preparation and properties of hydrogel surface chemistries enabling controlled and well-defined cell adhesion. The hydrogels may be prepared directly on plastic substrates, such as polystyrene slides or dishes, using a quick and experimentally simple photopolymerization process, compatible with photolithographic and microfluidic patterning methods. The intended application for these materials is as substrates for diagnostic cell adhesion assays, particularly for the analysis of human platelet function. The adsorption of fibrinogen and other platelet promoting molecules is shown to be completely inhibited by the hydrogel, provided that the film thickness is sufficient (>5 nm). This allows the hydrogel to be used as a matrix for presenting selected bioactive ligands without risking interference from nonspecifically adsorbed platelet adhesion factors, even in undiluted whole blood and blood plasma. This concept is demonstrated by preparing patterns of proteins on hydrogel surfaces, resulting in highly controlled platelet adhesion. Further insights into the protein immobilization and platelet adhesion processes are provided by studies using imaging surface plasmon resonance. The hydrogel surfaces used in this work appear to provide an ideal platform for cell adhesion studies of platelets, and potentially also for other cell types.
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| 16. |
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| 17. |
- Faxälv, Lars, et al.
(författare)
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Blood compatibility of photografted hydrogel coatings
- 2010
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Ingår i: ACTA BIOMATERIALIA. - : Elsevier Science B.V. Amsterdam. - 1742-7061. ; 6:7, s. 2599-2608
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this work we have evaluated the haemocompatibility of different surface modifications, intended for biomaterials and biosensor applications. Polystyrene slides were coated with thin hydrogel films by self-initiated photografting of four different monomers. The hydrogel surface modifications were thoroughly characterized and tested for their protein resistance and ability to facilitate platelet adhesion and activation of the coagulation system. There was very little protein adsorption from human plasma on the hydrogels formed from poly(ethylene glycol) methacrylate (PEGMA) and 2-hydroxyethyl methacrylate (HEMA). Platelet adhesion tests performed under both static and flow conditions showed that these coatings also demonstrated very high resistance towards platelet adhesion. A small amount of platelets were found to adhere to hydrogels formed from ethylene glycol methyl ether methacrylate (EGMEMA) and 2-carboxyethyl methacrylate (CEA). The polystyrene substrates themselves facilitated large amounts of platelet adhesion under both static and flow conditions. Utilizing a novel setup for imaging of coagulation, it was shown that none of the hydrogel surfaces activated the coagulation system to any great extent. We suggest that this simple fabrication method can be used to produce hydrogel coatings with unusually high blood compatibility, suitable for demanding biomaterials applications.
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| 18. |
- Fyrner, Timmy, et al.
(författare)
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Saccharide-Functionalized Alkanethiols for Fouling-Resistant Self-Assembled Monolayers: Synthesis, Monolayer Properties, and Antifouling Behavior
- 2011
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Ingår i: Langmuir. - : American Chemical Society. - 0743-7463 .- 1520-5827. ; 27:24, s. 15034-15047
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Tidskriftsartikel (refereegranskat)abstract
- We describe the synthesis of a series of mono-, di-, and trisaccharide-functionalized alkanethiols as well as the formation of fouling-resistant self-assembled monolayers (SAMs) from these. The SAls,,Is were characterized using ellipsometry, wetting measurements, and infrared reflection absorption spectroscopy (WAS). We show that the structure of the carbohydrate moiety affects the packing density and that this also alters the alkane chain organization. Upon increasing the size of the sugar moieties (from mono- to di- and trisaccharides), the structural qualities of the monolayers deteriorated with increasing disorder, and for the trisaccharide, slow reorganization dynamics in response to changes in the environmental polarity were observed. The antifouling properties of these SAMs were investigated through protein adsorption experiments from buffer solutions as well as settlement (attachment) tests using two common marine fouling species, zoospores of the green macroalga Ulva linza and cypris larvae of the barnacle Balanus amphitrite. The SAMs showed overall good resistance to fouling by both the proteins and the tested marine organisms. To improve the packing density of the SAMs with bulky headgroups, we employed mixed SAMs where the saccharide-thiols are diluted with a filler molecule having a small 2-hydroxyethyl headgroup. This method also provides a means by which the steric availability of sugar moieties can be varied, which is of interest for specific interaction studies with surface-bound sugars. The results of the surface dilution study and the low nonspecific adsorption onto the SAMs both indicate the feasibility of this approach.
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| 19. |
- Ladd, Brenton, et al.
(författare)
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Carbon isotopic signatures of soil organic matter correlate with leaf area index across woody biomes
- 2014
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 102:6, s. 1606-1611
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Tidskriftsartikel (refereegranskat)abstract
- Leaf area index (LAI), a measure of canopy density, is a key variable for modelling and understanding primary productivity, and also water use and energy exchange in forest ecosystems. However, LAI varies considerably with phenology and disturbance patterns, so alternative approaches to quantifying stand-level processes should be considered. The carbon isotope composition of soil organic matter (C-13(SOM)) provides a time-integrated, productivity-weighted measure of physiological and stand-level processes, reflecting biomass deposition from seasonal to decadal time scales.Our primary aim was to explore how well LAI correlates with C-13(SOM) across biomes.Using a global data set spanning large environmental gradients in tropical, temperate and boreal forest and woodland, we assess the strength of the correlation between LAI and C-13(SOM); we also assess climatic variables derived from the WorldClim database.We found that LAI was strongly correlated with C-13(SOM), but was also correlated with Mean Temperature of the Wettest Quarter, Mean Precipitation of Warmest Quarter and Annual Solar Radiation across and within biomes.Synthesis. Our results demonstrate that C-13(SOM) values can provide spatially explicit estimates of leaf area index (LAI) and could therefore serve as a surrogate for productivity and water use. While C-13(SOM) has traditionally been used to reconstruct the relative abundance of C-3 versus C-4 species, the results of this study demonstrate that within stable C-3- or C-4-dominated biomes, C-13(SOM) can provide additional insights. The fact that LAI is strongly correlated to C-13(SOM) may allow for a more nuanced interpretation of ecosystem properties of palaeoecosystems based on palaeosol C-13 values.
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| 20. |
- Liang, Min, et al.
(författare)
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Combined lack of estrogen receptors alpha and beta affects vascular iNOS protein expression.
- 2003
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Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 1432-0878 .- 0302-766X. ; 313:1, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- Endothelial and vascular smooth muscle cells express both estrogen receptor (ER) agr and beta. Recent findings indicate that vascular ERbeta and ERagr may substitute for one another. Here, we investigate vascular morphology, contractility and protein expression in intact aorta from adult (4 months old) female mice lacking both ERagr and ERbeta (DERKO). The body weights were 17% higher (P<0.01) in DERKO than in wild-type mice. Vascular morphology, investigated in paraffin sections from aorta stained with hematoxylin-eosin or van Gieson, was identical in DERKO and wild-type mice. Endothelial cells were clearly visible in aorta of both DERKO and wild-type animals. Morphometric analysis of media thickness and wall to lumen ratio using a computerized image analyzing system demonstrated no differences between the two groups of mice. The vascular expression of endothelial nitric oxide synthase (eNOS, NOS III) and inducible nitric oxide synthase (iNOS, NOS II) was investigated using Western blotting. Aorta from both DERKO and wild-type mice expressed iNOS protein, but the iNOS expression was 3 times lower (P<0.05) in DERKO compared to wild-type mice. No difference in eNOS protein level between the two groups of animals was observed. Force responses to noradrenaline, determined either in the absence or in the presence of the nitric oxide synthase inhibitor l-NAME and the cyclo-oxygenase inhibitor indomethacin, were unaffected by the lack of functional ERagr/ERbeta. In summary, combined lack of functional ERagr and ERbeta lowers the vascular expression of iNOS but has no effects on morphology, eNOS expression, and noradrenaline sensitivity in the intact aorta.
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