| 11. |
- Kontny, Frederic, et al.
(författare)
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Pentraxin-3 vs C-reactive protein and other prognostic biomarkers in acute coronary syndrome : A substudy of the Platelet Inhibition and Patients Outcomes (PLATO) trial
- 2020
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 2048-8726 .- 2048-8734. ; 9:4, s. 313-322
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: We investigated the dynamics, associations with patient characteristics, other biomarkers, and clinical outcomes of pentraxin 3 in acute coronary syndrome.METHODS AND RESULTS: In multivariate analyses, pentraxin 3 measured in 5154 patients randomised in the Platelet Inhibition and Patients Outcomes (PLATO) trial (NCT00391872) was compared with leukocytes, high-sensitivity C-reactive protein, interleukin-6, cystatin C, N-terminal prohormone brain natriuretic peptide, high-sensitivity troponin T and growth differentiation factor 15 concerning prediction of clinical outcome. Pentraxin 3 peaked earlier than high-sensitivity C-reactive protein and was more strongly correlated with N-terminal prohormone brain natriuretic peptide and high-sensitivity troponin T than with high-sensitivity C-reactive protein. The frequency of cardiovascular death, spontaneous myocardial infarction or stroke by quartiles of pentraxin 3 at admission was 6.1%, 7.3%, 9.7% and 10.7%, respectively ( p<0.0001). The hazard ratio per 50% increase of pentraxin 3 was 1.13 (95% confidence interval: 1.07-1.19), p<0.0001. This association remained significant after stepwise adjustments for leukocytes/high-sensitivity C-reactive protein (1.09 (1.02-1.15)), p=0.009, interleukin-6 (1.07 (1.01-1.14)), p=0.026, and cystatin C (1.07 (1.00-1.13)), p=0.044, but not after adjustment for N-terminal prohormone brain natriuretic peptide, high-sensitivity troponin T and growth differentiation factor 15. Admission pentraxin 3 was also associated with several of the individual endpoint components (cardiovascular death/spontaneous myocardial infarction; p=0.008, cardiovascular death; p=0.026, and spontaneous myocardial infarction; p=0.017), but not with stroke. Pentraxin 3 measured in the chronic phase (i.e. at one month) was still predictive of the composite endpoint in univariate analysis (1.12 (1.04-1.20) per 50% increase) p=0.0024, but not after adjustment for the other biomarkers.CONCLUSION: Admission level of pentraxin 3 is a modestly stronger predictor than high-sensitivity C-reactive protein and interleukin-6, but not than N-terminal prohormone brain natriuretic peptide or high-sensitivity troponin T, concerning cardiovascular outcome in acute coronary syndrome. Pentraxin 3 is more strongly correlated with N-terminal prohormone brain natriuretic peptide and high-sensitivity troponin T than with high-sensitivity C-reactive protein.
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| 12. |
- Kristensen, Jeppe A., et al.
(författare)
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Background insect herbivory increases with local elevation but makes minor contribution to element cycling along natural gradients in the Subarctic
- 2020
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 10:20, s. 11684-11698
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Tidskriftsartikel (refereegranskat)abstract
- Herbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to temperature shifts (ectothermal), the abundances of insects in high-latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests, research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature, and precipitation to allow evaluation of consistency in local versus regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was similar to 1.6% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N, and P fluxes from canopy to soil associated with BIH were 1-2 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N, and P weathering estimated from the literature. Despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lack of consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.
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| 13. |
- Kropp, Heather, et al.
(författare)
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Shallow soils are warmer under trees and tall shrubs across Arctic and Boreal ecosystems
- 2021
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Soils are warming as air temperatures rise across the Arctic and Boreal region concurrent with the expansion of tall-statured shrubs and trees in the tundra. Changes in vegetation structure and function are expected to alter soil thermal regimes, thereby modifying climate feedbacks related to permafrost thaw and carbon cycling. However, current understanding of vegetation impacts on soil temperature is limited to local or regional scales and lacks the generality necessary to predict soil warming and permafrost stability on a pan-Arctic scale. Here we synthesize shallow soil and air temperature observations with broad spatial and temporal coverage collected across 106 sites representing nine different vegetation types in the permafrost region. We showed ecosystems with tall-statured shrubs and trees (>40 cm) have warmer shallow soils than those with short-statured tundra vegetation when normalized to a constant air temperature. In tree and tall shrub vegetation types, cooler temperatures in the warm season do not lead to cooler mean annual soil temperature indicating that ground thermal regimes in the cold-season rather than the warm-season are most critical for predicting soil warming in ecosystems underlain by permafrost. Our results suggest that the expansion of tall shrubs and trees into tundra regions can amplify shallow soil warming, and could increase the potential for increased seasonal thaw depth and increase soil carbon cycling rates and lead to increased carbon dioxide loss and further permafrost thaw.
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| 14. |
- Lett, Signe, et al.
(författare)
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Can bryophyte groups increase functional resolution in tundra ecosystems?
- 2022
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Ingår i: Arctic Science. - Ottawa : Canadian Science Publishing. - 2368-7460. ; 8:3, s. 609-637
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Tidskriftsartikel (refereegranskat)abstract
- The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.
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| 15. |
- Lett, Signe, et al.
(författare)
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Moss species and precipitation mediate experimental warming stimulation of growing season N2 fixation in subarctic tundra
- 2024
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 30:7
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Tidskriftsartikel (refereegranskat)abstract
- Climate change in high latitude regions leads to both higher temperatures and more precipitation but their combined effects on terrestrial ecosystem processes are poorly understood. In nitrogen (N) limited and often moss-dominated tundra and boreal ecosystems, moss-associated N2 fixation is an important process that provides new N. We tested whether high mean annual precipitation enhanced experimental warming effects on growing season N2 fixation in three common arctic-boreal moss species adapted to different moisture conditions and evaluated their N contribution to the landscape level. We measured in situ N2 fixation rates in Hylocomium splendens, Pleurozium schreberi and Sphagnum spp. from June to September in subarctic tundra in Sweden. We exposed mosses occurring along a natural precipitation gradient (mean annual precipitation: 571–1155 mm) to 8 years of experimental summer warming using open-top chambers before our measurements. We modelled species-specific seasonal N input to the ecosystem at the colony and landscape level. Higher mean annual precipitation clearly increased N2 fixation, especially during peak growing season and in feather mosses. For Sphagnum-associated N2 fixation, high mean annual precipitation reversed a small negative warming response. By contrast, in the dry-adapted feather moss species higher mean annual precipitation led to negative warming effects. Modelled total growing season N inputs for Sphagnum spp. colonies were two to three times that of feather mosses at an area basis. However, at the landscape level where feather mosses were more abundant, they contributed 50% more N than Sphagnum. The discrepancy between modelled estimates of species-specific N input via N2 fixation at the moss core versus ecosystem scale, exemplify how moss cover is essential for evaluating impact of altered N2 fixation. Importantly, combined effects of warming and higher mean annual precipitation may not lead to similar responses across moss species, which could affect moss fitness and their abilities to buffer environmental changes.
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| 16. |
- Lett, Signe, et al.
(författare)
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Mosses modify effects of warmer and wetter conditions on tree seedlings at the alpine treeline
- 2020
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 26:10, s. 5754-5766
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Tidskriftsartikel (refereegranskat)abstract
- Climate warming enables tree seedling establishment beyond the current alpine treeline, but to achieve this, seedlings have to establish within existing tundra vegetation. In tundra, mosses are a prominent feature, known to regulate soil temperature and moisture through their physical structure and associated water retention capacity. Moss presence and species identity might therefore modify the impact of increases in temperature and precipitation on tree seedling establishment at the arctic‐alpine treeline. We followed Betula pubescens and Pinus sylvestris seedling survival and growth during three growing seasons in the field. Tree seedlings were transplanted along a natural precipitation gradient at the subarctic‐alpine treeline in northern Sweden, into plots dominated by each of three common moss species and exposed to combinations of moss removal and experimental warming by open‐top chambers (OTCs). Independent of climate, the presence of feather moss, but not Sphagnum , strongly supressed survival of both tree species. Positive effects of warming and precipitation on survival and growth of B. pubescens seedlings occurred in the absence of mosses and as expected, this was partly dependent on moss species. P. sylvestris survival was greatest at high precipitation, and this effect was more pronounced in Sphagnum than in feather moss plots irrespective of whether the mosses had been removed or not. Moss presence did not reduce the effects of OTCs on soil temperature. Mosses therefore modified seedling response to climate through other mechanisms, such as altered competition or nutrient availability. We conclude that both moss presence and species identity pose a strong control on seedling establishment at the alpine treeline, and that in some cases mosses weaken climate‐change effects on seedling establishment. Changes in moss abundance and species composition therefore have the potential to hamper treeline expansion induced by climate warming.
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| 17. |
- Pascual, Didac, et al.
(författare)
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The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study
- 2021
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Ingår i: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 50:2, s. 375-392
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Forskningsöversikt (refereegranskat)abstract
- Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.
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| 18. |
- Ueland, Thor, et al.
(författare)
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ALCAM predicts future cardiovascular death in acute coronary syndromes : Insights from the PLATO trial
- 2020
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Ingår i: Atherosclerosis. - : Elsevier. - 0021-9150 .- 1879-1484. ; 293, s. 35-41
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIMS: Activated leukocyte cell adhesion molecule (ALCAM) is upregulated during inflammation and involved in transmigration of leukocytes and T-cell activation. We hypothesized that ALCAM might be associated with recurrent events in patients with acute coronary syndromes (ACS).METHODS: ALCAM was measured in serum obtained on admission, at discharge, 1 month and 6 months in a subgroup of 5165 patients admitted with ACS and included in the PLATelet inhibition and patient Outcomes (PLATO) trial (NCT00391872). The association between ALCAM and the composite endpoint and its components, including cardiovascular (CV) death, non-procedural spontaneous myocardial infarction (MI) or stroke during 1-year follow-up, was assessed by Cox proportional hazards models with incremental addition of clinical risk factors and biomarkers (including high-sensitivity troponin T, N-terminal pro-B-type natriuretic peptide and growth differentiation factor-15).RESULTS: The median (Q1-Q3) concentration of ALCAM at admission was 97 (80-116) ng/mL. A 50% higher level of ALCAM on admission was associated with a hazard ratio (HR) of 1.16 (95% confidence interval [1.00-1.34] p = 0.043) for the composite endpoint in fully adjusted analysis, mainly driven by the association with CV death (HR 1.45 [1.16-1.82] p = 0.0012).CONCLUSIONS: In patients with ACS, admission level of ALCAM was independently associated with adverse outcome including CV death even after adjustment for established inflammatory and cardiac biomarkers.
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