| 21. |
- Andresen, Camilla S., et al.
(författare)
-
Sediment discharge from Greenland's marine-terminating glaciers is linked with surface melt
- 2024
-
Ingår i: Nature Communications. - 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- Sediment discharged from the Greenland Ice Sheet delivers nutrients to marine ecosystems around Greenland and shapes seafloor habitats. Current estimates of the total sediment flux are constrained by observations from land-terminating glaciers only. Addressing this gap, our study presents a budget derived from observations at 30 marine-margin locations. Analyzing sediment cores from nine glaciated fjords, we assess spatial deposition since 1950. A significant correlation is established between mass accumulation rates, normalized by surface runoff, and distance down-fjord. This enables calculating annual sediment flux at any fjord point based on nearby marine-terminating outlet glacier melt data. Findings reveal a total annual sediment flux of 1.324 + /- 0.79 Gt yr-1 over the period 2010-2020 from all marine-terminating glaciers to the fjords. These estimates are valuable for studies aiming to understand the basal ice sheet conditions and for studies predicting ecosystem changes in Greenland's fjords and offshore areas as the ice sheet melts and sediment discharge increase.
|
|
| 22. |
- Borggren, Marie, et al.
(författare)
-
Evolution of DC-SIGN use revealed by fitness studies of R5 HIV-I variants emerging during AIDS progression
- 2008
-
Ingår i: Retrovirology. - : Springer Science and Business Media LLC. - 1742-4690. ; 5:28
-
Tidskriftsartikel (refereegranskat)abstract
- Background: At early stages of infection CCR5 is the predominant HIV-1 coreceptor, but in approximately 50% of those infected CXCR4-using viruses emerge with disease progression. This coreceptor switch is correlated with an accelerated progression. However, those that maintain virus exclusively restricted to CCR5 (R5) also develop AIDS. We have previously reported that R5 variants in these "non-switch virus" patients evolve during disease progression towards a more replicative phenotype exhibiting altered CCR5 coreceptor interactions. DC-SIGN is a C-type lectin expressed by dendritic cells that HIV-1 may bind and utilize for enhanced infection of T cells in trans. To further explore the evolution of the R5 phenotype we analyzed sequential R5 isolates obtained before and after AIDS onset, i.e. at the chronic stage and during end-stage disease, with regard to efficiency of DC-SIGN use in trans-infections. Results: Results from binding and trans-infection assays showed that R5 viruses emerging during end-stage AIDS disease displayed reduced ability to use DC-SIGN. To better understand viral determinants underlying altered DC-SIGN usage by R5 viruses, we cloned and sequenced the HIV-1 env gene. We found that end-stage R5 viruses lacked potential N-linked glycosylation sites (PNGS) in the gp120 V2 and V4 regions, which were present in the majority of the chronic stage R5 variants. One of these sites, amino acid position 160 (aa160) in the V2 region, also correlated with efficient use of DC-SIGN for binding and trans-infections. In fitness assays, where head-to-head competitions between chronic stage and AIDS R5 viruses were setup in parallel direct and DCSIGN-mediated infections, results were further supported. Competitions revealed that R5 viruses obtained before AIDS onset, containing the V2 PNGS at aa160, were selected for in the transinfection. Whereas, in agreement with our previous studies, the opposite was seen in direct target cell infections where end-stage viruses out-competed the chronic stage viruses. Conclusion: Results of our study suggest R5 virus variants with diverse fitness for direct and DCSIGN-mediated trans-infections evolve within infected individuals at end-stage disease. In addition, our results point to the importance of a glycosylation site within the gp120 V2 region for efficient DC-SIGN use of HIV-1 R5 viruses.
|
|
| 23. |
- Burman, Pia, et al.
(författare)
-
Limited value of cabergoline in Cushing's disease : a prospective study of a 6-week treatment in 20 patients
- 2016
-
Ingår i: European Journal of Endocrinology. - : Bioscientifica. - 0804-4643 .- 1479-683X. ; 174:1, s. 17-24
-
Tidskriftsartikel (refereegranskat)abstract
- CONTEXT AND OBJECTIVE: The role of cabergoline in Cushing's disease (CD) remains controversial. The experience is limited to case reports and few open studies that report the effects determined after ≥1 month of treatment. In prolactinomas and dopamine-responsive GH-secreting tumours, effects of cabergoline are seen within days or weeks. Here, we searched for short-term effects of cabergoline in CD.DESIGN: Twenty patients (19 naïve and one recurrent) were included in a prospective study. Cabergoline was administered in increasing doses of 0.5-5 mg/week over 6 weeks.METHODS: Urinary free cortisol (UFC) 24 h, morning cortisol and ACTH, and salivary cortisol at 0800, 1600 and 2300 h were determined once weekly throughout. Diurnal curves (six samples) of serum cortisol were measured at start and end.RESULTS: At study end, the median cabergoline dose was 5 mg, range 2.5-5 mg/week. The prolactin levels, markers of compliance, were suppressed in all patients. During the treatment, hypercortisolism varied, gradual and dose-dependent reductions were not seen. Five patients had a >50% decrease of UFC, three had a >50% rise of UFC. Salivary cortisol at 2300 h showed a congruent >50% change with UFC in two of the five cases with decreased UFC, and in one of the three cases with increased UFC. One patient with decreases in both UFC and 2300 h salivary cortisol also had a reduction in diurnal serum cortisol during the course of the study.CONCLUSIONS: Cabergoline seems to be of little value in the management of CD. Only one patient had a response-like pattern. Given the known variability of disease activity in CD, this might represent a chance finding.
|
|
| 24. |
- Bäck, Sophia, et al.
(författare)
-
Assessment of transmitral and left atrial appendage flow rate from cardiac 4D-CT
- 2023
-
Ingår i: Communications Medicine. - : Springer Nature. - 2730-664X. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- Plain language summaryAssessing the blood flow inside the heart is important in diagnosis and treatment of various cardiovascular diseases, such as atrial fibrillation or heart failure. We developed a method to accurately track the motion of the heart walls over the course of a heartbeat in three-dimensional Computed Tomography (CT) images. Based on the motion, we calculated the amount of blood passing through the mitral valve and the left atrial appendage orifice, which are markers used in the diagnostic of heart failure and assessment of stroke risk in atrial fibrillation. The results agreed well with measurements from 4D flow MRI, an imaging technique that measures blood velocities. Our method could broaden the use of CT and make additional exams redundant. It can even be used to calculate the blood flow inside the heart. BackgroundCardiac time-resolved CT (4D-CT) acquisitions provide high quality anatomical images of the heart. However, some cardiac diseases require assessment of blood flow in the heart. Diastolic dysfunction, for instance, is diagnosed by measuring the flow through the mitral valve (MV), while in atrial fibrillation, the flow through the left atrial appendage (LAA) indicates the risk for thrombus formation. Accurate validated techniques to extract this information from 4D-CT have been lacking, however.MethodsTo measure the flow rate though the MV and the LAA from 4D-CT, we developed a motion tracking algorithm that performs a nonrigid deformation of the surface separating the blood pool from the myocardium. To improve the tracking of the LAA, this region was deformed separately from the left atrium and left ventricle. We compared the CT based flow with 4D flow and short axis MRI data from the same individual in 9 patients.ResultsFor the mitral valve flow, good agreement was found for the time span between the early and late diastolic peak flow (bias: <0.1 s). The ventricular stroke volume is similar compared to short-axis MRI (bias 3 ml). There are larger differences in the diastolic peak flow rates, with a larger bias for the early flow rate than the late flow rate. The peak LAA outflow rate measured with both modalities matches well (bias: -6 ml/s).ConclusionsOverall, the developed algorithm provides accurate tracking of dynamic cardiac geometries resulting in similar flow rates at the MV and LAA compared to 4D flow MRI. Back et al. describe a motion tracking algorithm to measure the flow rate through the mitral valve (MV) and the left atrial appendage (LAA) from 4D-CT data. The developed algorithm provided accurate tracking of dynamic cardiac geometries resulting in similar flow rates at the MV and LAA to those measured by 4D flow MRI.
|
|
| 25. |
- Casalongue, Hernan G. Sanchez, et al.
(författare)
-
Operando Characterization of an Amorphous Molybdenum Sulfide Nanoparticle Catalyst during the Hydrogen Evolution Reaction
- 2014
-
Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:50, s. 29252-29259
-
Tidskriftsartikel (refereegranskat)abstract
- Molybdenum sulfide structures, particularly amorphous MoS3 nanoparticles, are promising materials in the search for cost-effective and scalable water-splitting catalysts. Ex situ observations show that the nanoparticles exhibit a composition change from MoS3 to defective MoS2 when subjected to hydrogen evolution reaction (HER) conditions, raising questions regarding the active surface sites taking part in the reaction. We tracked the in situ transformation of amorphous MoS3 nanoparticles under HER conditions through ambient pressure X-ray photoelectron spectroscopy and performed density functional theory studies of model MoSx systems. We demonstrate that, under operating conditions, surface sites are converted from MoS3 to MoS2 in a gradual manner and that the electrolytic current densities are proportional to the extent of the transformation. We also posit that it is the MoS2 edge-like sites that are active during HER, with the high activity of the catalyst being attributed to the increase in surface MoS2 edge-like sites after the reduction of MoS3 sites.
|
|
| 26. |
- Cornelissen, Johannes H C, et al.
(författare)
-
Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
-
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.
|
|
| 27. |
|
|
| 28. |
|
|
| 29. |
|
|
| 30. |
|
|
