| 1. |
- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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| 2. |
- Elmendorf, Sarah C., et al.
(författare)
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Global assessment of experimental climate warming on tundra vegetation : heterogeneity over space and time
- 2012
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 15:2, s. 164-175
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Forskningsöversikt (refereegranskat)abstract
- Understanding the sensitivity of tundra vegetation to climate warming is critical to forecasting future biodiversity and vegetation feedbacks to climate. In situ warming experiments accelerate climate change on a small scale to forecast responses of local plant communities. Limitations of this approach include the apparent site-specificity of results and uncertainty about the power of short-term studies to anticipate longer term change. We address these issues with a synthesis of 61 experimental warming studies, of up to 20 years duration, in tundra sites worldwide. The response of plant groups to warming often differed with ambient summer temperature, soil moisture and experimental duration. Shrubs increased with warming only where ambient temperature was high, whereas graminoids increased primarily in the coldest study sites. Linear increases in effect size over time were frequently observed. There was little indication of saturating or accelerating effects, as would be predicted if negative or positive vegetation feedbacks were common. These results indicate that tundra vegetation exhibits strong regional variation in response to warming, and that in vulnerable regions, cumulative effects of long-term warming on tundra vegetation and associated ecosystem consequences have the potential to be much greater than we have observed to date.
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| 3. |
- Gregersen, Ida, et al.
(författare)
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Legumain in Acute Coronary Syndromes : A Substudy of the PLATO (Platelet Inhibition and Patient Outcomes) Trial
- 2020
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Ingår i: Journal of the American Heart Association. - : WILEY. - 2047-9980. ; 9:17
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The cysteine protease legumain is increased in patients with atherosclerosis, but its causal role in atherogenesis and cardiovascular disease is still unclear. The aim of the study was to investigate the association of legumain with clinical outcome in a large cohort of patients with acute coronary syndrome. METHODS AND RESULTS : Serum levels of legumain were analyzed in 4883 patients with acute coronary syndrome from a substudy of the PLATO (Platelet Inhibition and Patient Outcomes) trial. Levels were analyzed at admission and after 1 month follow-up. Associations between legumain and a composite of cardiovascular death, spontaneous myocardial infarction or stroke, and its individual components were assessed by multivariable Cox regression analyses. At baseline, a 50% increase in legumain level was associated with a hazard ratio (HR) of 1.13 (95% CI, 1.04-1.21),P=0.0018, for the primary composite end point, adjusted for randomized treatment. The association remained significant after adjustment for important clinical and demographic variables (HR, 1.10; 95% CI, 1.02-1.19;P=0.013) but not in the fully adjusted model. Legumain levels at 1 month were not associated with the composite end point but were negatively associated with stroke (HR, 0.62; 95% CI, 0.44-0.88;P=0.0069), including in the fully adjusted model (HR, 0.57; 95% CI, 0.37-0.88;P=0.0114). CONCLUSIONS: Baseline legumain was associated with the primary outcome in patients with acute coronary syndrome, but not in the fully adjusted model. The association between high levels of legumain at 1 month and decreased occurrence of stroke could be of interest from a mechanistic point of view, illustrating the potential dual role of legumain during atherogenesis and acute coronary syndrome. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00391872.
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| 4. |
- 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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| 5. |
- Olsrud, Maria, et al.
(författare)
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Responses of fungal root colonization, plant cover and leaf nutrients to long-term exposure to elevated atmospheric CO2 and warming in a subarctic birch forest understory
- 2010
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 16:6, s. 1820-1829
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Tidskriftsartikel (refereegranskat)abstract
- Responses of the mycorrhizal fungal community in terrestrial ecosystems to global change factors are not well understood. However, virtually all land plants form symbiotic associations with mycorrhizal fungi, with approximately 20% of the plants' net primary production transported down to the fungal symbionts. In this study, we investigated how ericoid mycorrhiza (ErM), fine endophytes (FE) and dark septate endophytes (DSE) in roots responded to elevated atmospheric CO2 concentrations and warming in the dwarf shrub understory of a birch forest in the subarctic region of northern Sweden. To place the belowground results into an ecosystem context we also investigated how plant cover and nutrient concentrations in leaves responded to elevated atmospheric CO2 concentrations and warming. The ErM colonization in ericaceous dwarf shrubs increased under elevated atmospheric CO2 concentrations, but did not respond to warming following 6 years of treatment. This suggests that the higher ErM colonization under elevated CO2 might be due to increased transport of carbon belowground to acquire limiting resources such as N, which was diluted in leaves of ericaceous plants under enhanced CO2. The elevated CO2 did not affect total plant cover but the plant cover was increased under warming, which might be due to increased N availability in soil. FE colonization in grass roots decreased under enhanced CO2 and under warming, which might be due to increased root growth, to which the FE fungi could not keep up, resulting in proportionally lower colonization. However, no responses in aboveground cover of Deschampsia flexuosa were seen. DSE hyphal colonization in grass roots significantly increased under warmer conditions, but did not respond to elevated CO2. This complex set of responses by mycorrhizal and other root-associated fungi to global change factors of all the fungal types studied could have broad implications for plant community structure and biogeochemistry of subarctic ecosystems.
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| 6. |
- 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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| 7. |
- Tyrefors, Niklas, et al.
(författare)
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Two new types of assays to determine protein concentrations in biological fluids using mass spectrometry of intact proteins with cystatin C in spinal fluid as an example
- 2014
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 74:6, s. 546-554
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Tidskriftsartikel (refereegranskat)abstract
- There is no reference method that is generally acknowledged to be unbiased for the determination of the concentration of any protein in biological fluids. This is probably because mass spectrometry (MS) methods acknowledged as reference methods for determination of low molecular mass substances in biological fluids, e.g. creatinine, have been difficult to adapt for proteins. Here we suggest two tentative MS methods, which might be used as reference methods for the determination of protein concentrations in biological fluids. One is based upon the addition to the fluid of a non-proteome reference protein, very similar to the one to be measured, and analyzing the ratio between the corresponding peaks in a selected ion monitoring (SIM) chromatogram. We call this method LC-MS-NPRP (NPRP, Non-Proteome Reference Protein). The other method is based upon the classical standard addition assay for low molecular mass substances. The results of these assays for cystatin C in spinal fluid were compared to those obtained by an immunoassay. Both methods indicated lower concentration than the immunoassay. This was found to be due to the presence of a significant fraction of monohydroxylated cystatin C in spinal fluid. It turned out that the sum of the unhydroxylated and hydroxylated cystatin C concentrations, determined by either of the two MS methods, were close to the results obtained by the immunoassay. These MS-based methods analyze intact proteins and therefore seem more suitable for the determination of protein concentrations in biological fluids than other MS-based methods requiring proteolytic degradation with its inherent lack of precision.
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| 8. |
- Ueland, Thor, et al.
(författare)
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Admission Levels of DKK1 (Dickkopf-1) Are Associated With Future Cardiovascular Death in Patients With Acute Coronary Syndromes
- 2019
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 39:2, s. 294-302
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Tidskriftsartikel (refereegranskat)abstract
- Objective- The Wnt/wingless signaling antagonist DKK1 (dickkopf-1) regulates platelet-mediated inflammation and may contribute to plaque destabilization. We hypothesized that DKK1 would be associated with cardiovascular outcomes.Approach and Results- We determined DKK1 levels in serum samples obtained before randomization, at discharge, and 1 and 6 months in a subset of 5165 patients with acute coronary syndromes in the PLATO trial (Platelet Inhibition and Patient Outcomes; NCT00391872). The median (interquartile range) DKK1 concentrations were 0.61 (0.20-1.27) ng/mL at baseline and increased during follow-up. The hazard ratio (95% CIs) for the composite end point (cardiovascular death, nonprocedural spontaneous myocardial infarction, or stroke) during 1 year of follow-up, per 50% increase in baseline DKK1 concentration, was 1.06 (1.02-1.10), P=0.0011, and remained significant in fully adjusted analysis with 14 conventional clinical and demographic and 6 biochemical variables, including NT-proBNP (N-terminal pro-B-type natriuretic peptide), hs-TnT (high-sensitivity troponin T), and GDF-15 (growth differentiation factor 15; 1.05 [1.00-1.09]; P=0.028). This association was mainly driven by the association with cardiovascular death, where a gradual increase in event rates was observed with increasing quartiles of DKK1 (2.7%, 3.0%, 4.3%, and 5.0%) and remained significant and unmodified in fully adjusted analysis (hazard ratio, 1.10 [1.04-1.17]; P=0.002). Change in DKK1 and levels at 1 month were unrelated to outcomes. A modifying effect of ticagrelor on DKK1 discharge levels was observed but not associated with prognosis.Conclusions- In patients with acute coronary syndromes treated with dual antiplatelet treatment, admission DKK1 levels were independently associated with a composite of cardiovascular death, myocardial infarction, or stroke and with cardiovascular death alone.
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| 9. |
- 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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| 10. |
- Ueland, Thor, et al.
(författare)
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Osteoprotegerin Is Associated With Major Bleeding But Not With Cardiovascular Outcomes in Patients With Acute Coronary Syndromes : Insights From the PLATO (Platelet Inhibition and Patient Outcomes) Trial
- 2018
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Ingår i: Journal of the American Heart Association. - : WILEY. - 2047-9980. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Background-Elevated levels of osteoprotegerin, a secreted tumor necrosis factor-related molecule, might be associated with adverse outcomes in patients with coronary artery disease. We measured plasma osteoprotegerin concentrations on hospital admission, at discharge, and at 1 and 6months after discharge in a predefined subset (n=5135) of patients with acute coronary syndromes in the PLATO (Platelet Inhibition and Patient Outcomes) trial. Methods and Results-The associations between osteoprotegerin and the composite end point of cardiovascular death, nonprocedural spontaneous myocardial infarction or stroke, and non-coronary artery bypass grafting major bleeding during 1year of follow-up were assessed by Cox proportional hazards models. Event rates of the composite end point per increasing quartile groups at baseline were 5.2%, 7.5%, 9.2%, and 11.9%. A 50% increase in osteoprotegerin level was associated with a hazard ratio (HR) of 1.31 (95% confidence interval [CI], 1.21-1.42) for the composite end point but was not significant in adjusted analysis (ie, clinical characteristics and levels of C-reactive protein, troponin T, NT-proBNP [N-terminal pro-B-type natriuretic peptide], and growth differentiation factor-15). The corresponding rates of non-coronary artery bypass grafting major bleeding were 2.4%, 2.2%, 3.8%, and 7.2%, with an unadjusted HR of 1.52 (95% CI, 1.36-1.69), and a fully adjusted HR of 1.26 (95% CI, 1.09-1.46). The multivariable association between the osteoprotegerin concentrations and the primary end point after 1month resulted in an HR of 1.09 (95% CI, 0.89-1.33); for major bleeding after 1month, the HR was 1.33 (95% CI, 0.91-1.96). Conclusions-In patients with acute coronary syndrome treated with dual antiplatelet therapy, osteoprotegerin was an independent marker of major bleeding but not of ischemic cardiovascular events. Thus, high osteoprotegerin levels may be useful in increasing awareness of increased bleeding risk in patients with acute coronary syndrome receiving antithrombotic therapy.
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