| 1. |
- Callaghan, Terry, et al.
(författare)
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Multi-Decadal Changes in Tundra Environments and Ecosystems : Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)
- 2011
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:6, s. 705-716
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the responses of tundra systemsto global change has global implications. Most tundraregions lack sustained environmental monitoring and oneof the only ways to document multi-decadal change is toresample historic research sites. The International PolarYear (IPY) provided a unique opportunity for such researchthrough the Back to the Future (BTF) project (IPY project#512). This article synthesizes the results from 13 paperswithin this Ambio Special Issue. Abiotic changes includeglacial recession in the Altai Mountains, Russia; increasedsnow depth and hardness, permafrost warming, andincreased growing season length in sub-arctic Sweden;drying of ponds in Greenland; increased nutrient availabilityin Alaskan tundra ponds, and warming at mostlocations studied. Biotic changes ranged from relativelyminor plant community change at two sites in Greenland tomoderate change in the Yukon, and to dramatic increasesin shrub and tree density on Herschel Island, and in subarcticSweden. The population of geese tripled at one sitein northeast Greenland where biomass in non-grazed plotsdoubled. A model parameterized using results from a BTFstudy forecasts substantial declines in all snowbeds andincreases in shrub tundra on Niwot Ridge, Colorado overthe next century. In general, results support and provideimproved capacities for validating experimental manipulation,remote sensing, and modeling studies.
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| 2. |
- Villarroel, Brian, et al.
(författare)
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The VASCO project : 100 red transients and their follow up
- 2020
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Ingår i: Proceedings of the International Astronautical Congress, IAC. - : International Astronautical Federation, IAF.
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Konferensbidrag (refereegranskat)abstract
- The Vanishing & Appearing Sources during a Century of Observations (VASCO) project investigates astronomical surveys spanning a 70 years time interval, searching for unusual and exotic transients. We present herein the VASCO Citizen Science Project, that uses three different approaches to the identification of unusual transients in a given set of candidates: hypothesis-driven, exploratory-driven and machine learning-driven (which is of particular benefit for SETI searches). To address the big data challenge, VASCO combines methods from the Virtual Observatory, a user-aided machine learning and visual inspection through citizen science. In this article, we demonstrate the citizen science project, the new and improved candidate selection process and give a progress report. We also present the VASCO citizen science network led by amateur astronomy associations mainly located in Algeria, Cameroon and Nigeria. At the moment of writing, the citizen science project has carefully examined 12,000 candidate image pairs in the data, and has so far identified 713 objects classified as “vanished”. The most interesting candidates will be followed up with optical and infrared imaging, together with the observations by the most potent radio telescopes.
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| 3. |
- Bergstedt, J, et al.
(författare)
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The immune factors driving DNA methylation variation in human blood
- 2022
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1, s. 5895-
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Tidskriftsartikel (refereegranskat)abstract
- Epigenetic changes are required for normal development, yet the nature and respective contribution of factors that drive epigenetic variation in humans remain to be fully characterized. Here, we assessed how the blood DNA methylome of 884 adults is affected by DNA sequence variation, age, sex and 139 factors relating to life habits and immunity. Furthermore, we investigated whether these effects are mediated or not by changes in cellular composition, measured by deep immunophenotyping. We show that DNA methylation differs substantially between naïve and memory T cells, supporting the need for adjustment on these cell-types. By doing so, we find that latent cytomegalovirus infection drives DNA methylation variation and provide further support that the increased dispersion of DNA methylation with aging is due to epigenetic drift. Finally, our results indicate that cellular composition and DNA sequence variation are the strongest predictors of DNA methylation, highlighting critical factors for medical epigenomics studies.
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| 4. |
- Bergstedt, K., et al.
(författare)
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Changes in insulin-like growth factor 1 receptor density after transient cerebral ischemia in the rat : Lack of protection against ischemic brain damage following injection of insulin-like growth factor 1
- 1993
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 0271-678X .- 1559-7016. ; 13:5, s. 895-898
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Tidskriftsartikel (refereegranskat)abstract
- Binding of 125I-insulin-like growth factor-1 (125I-IGF-1) to rat brain slices was studied after 15 min of two-vessel occlusion ischemia and 1 h to 4 days of recirculation. Ligand binding in the hippocampus increased at 6 h post ischemia in the CA1 and CA3 regions and the dentate gyrus, suggesting that the IGF-1 receptors were up-regulated, while no change was seen in neocortex and striatum. Intracerebroventricular injections of IGF-1 (2 μg) prior to and after transient cerebral ischemia did not reduce neuronal damage. The increased up-regulation on IGF-1 receptors and the absence of neuroprotection by IGF-1 suggest that the intracellular signal transduction chain activated by the IGF-1 receptor may be interrupted.
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| 6. |
- Daníelsdóttir, Hilda Björk, et al.
(författare)
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Adverse Childhood Experiences and Adult Mental Health Outcomes
- 2024
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Ingår i: JAMA psychiatry. - : American Medical Association (AMA). - 2168-6238 .- 2168-622X. ; 81:6, s. 586-594
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE: Exposure to adverse childhood experiences (ACEs) has consistently been associated with multiple negative mental health outcomes extending into adulthood. However, given that ACEs and psychiatric disorders cluster within families, it remains to be comprehensively assessed to what extent familial confounding contributes to associations between ACEs and clinically confirmed adult psychiatric disorders.OBJECTIVE: To investigate whether associations between ACEs and adult mental health outcomes remain after adjusting for familial (genetic and environmental) confounding.DESIGN, SETTING, AND PARTICIPANTS: This Swedish twin cohort study used a discordant twin pair design based on monozygotic (MZ) and dizygotic (DZ) twins. A total of 25 252 adult twins (aged 18-47 years) from the Swedish Twin Registry born between 1959 and 1998 were followed up from age 19 years until 2016, with a maximum follow-up time of 39 years. Data were analyzed from April 2022 to November 2023.EXPOSURES: A total of 7 ACEs, including family violence, emotional abuse or neglect, physical neglect, physical abuse, sexual abuse, rape, and hate crime, were assessed with items from the Life Stressor Checklist-Revised in a web-based survey.MAIN OUTCOMES AND MEASURES: Adult (ages >18 years) clinical diagnosis of psychiatric disorders (ie, depressive, anxiety, alcohol or drug misuse, or stress-related disorders) were obtained from the Swedish National Patient Register.RESULTS: Of 25 252 twins included in the study (15 038 female [59.6%]; mean [SD] age at ACE assessment, 29.9 [8.7] years), 9751 individuals (38.6%) reported exposure to at least 1 ACE. A greater number of ACEs was associated with increased odds of any psychiatric disorder in the full cohort (odds ratio [OR] per additional ACE, 1.52; 95% CI, 1.48-1.57). The association remained but ORs per additional ACE were attenuated in DZ (1.29; 95% CI, 1.14-1.47) and MZ (1.20; 95% CI, 1.02-1.40) twin pairs. Individuals who were exposed to sexual abuse compared with those who were not exposed had increased odds of any clinically confirmed psychiatric disorder in all comparisons: full cohort (OR, 3.09; 95% CI, 2.68-3.56), DZ twin pairs (OR, 2.10; 95% CI, 1.33-3.32), and MZ twin pairs (1.80; 95% CI, 1.04-3.11).CONCLUSIONS AND RELEVANCE: This study found that associations between ACEs and adult mental health outcomes remained after controlling for shared genetic and environmental factors, which was particularly evident after multiple ACEs or sexual abuse. These findings suggest that targeted interventions may be associated with reduced risks of future psychopathology.
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| 7. |
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| 8. |
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| 9. |
- Deshpande, J, et al.
(författare)
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Ultrastructural changes in the hippocampal CA1 region following transient cerebral ischemia: evidence against programmed cell death.
- 1992
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Ingår i: Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale. - 0014-4819. ; 88:1, s. 91-105
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Tidskriftsartikel (refereegranskat)abstract
- The ultrastructural changes in the pyramidal neurons of the CA1 region of the hippocampus were studied 6 h, 24 h, 48 h, and 72 h following a transient 10 min period of cerebral ischemia induced by common carotid occlusion combined with hypotension. The pyramidal neurons showed delayed neuronal death (DND), i.e. at 24 h and 48 h postischemia few structural alterations were noted in the light microscope, while at 72 h extensive neuronal degeneration was apparent. The most prominent early ultrastructural changes were polysome disaggregation, and the appearance of electron-dense fluffy dark material associated with tubular saccules. Mitochondria and nuclear elements appeared intact until frank neuronal degeneration. The dark material accumulated with extended periods of recirculation in soma and in the main trunks of proximal dendrites, often beneath the plasma membrane, less frequently in the distal dendrites and seldom in spines. Protein synthesis inhibitors (anisomycin, cycloheximide) and an RNA synthesis inhibitor (actinomycin D), administered by intrahippocampal injections or subcutaneously, did not mitigate neuronal damage. Therefore, DND is probably not apoptosis or a form of programmed cell death. We propose that the dark material accumulating in the postischemic period represents protein complexes, possibly aggregates of proteins or internalized plasma membrane fragments, which may disrupt vital cellular structure and functions, leading to cell death.
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| 13. |
- Petersson, L. K., et al.
(författare)
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Changing land use and increasing abundance of deer cause natural regeneration failure of oaks: Six decades of landscape-scale evidence
- 2019
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 444, s. 299-307
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Tidskriftsartikel (refereegranskat)abstract
- Many tree species worldwide are suffering from slow or failed natural regeneration with dramatic consequences for biodiversity and ecosystem services. However, it is difficult to disentangle the complex effects of factors influencing regeneration processes on long-lived tree species at large scales. In this study, we use long-term data from the Swedish National Forest Inventory (1953-2015) combined with deer hunting data (1960-2015) to reveal experimentally-intractable processes impeding oak (Quercus spp.) regeneration in southern Sweden. Oak-dominated ecosystems are widespread in northern temperate regions, where oaks are foundation species with disproportionate importance for biodiversity and ecosystem functions. Our study reveals that during the last six decades, oak tree numbers and standing volume have continuously increased, while natural regeneration of oak declined steeply after the early 1980s. We connect this decline to denser and darker forests, combined with increased abundance of deer. Land use changes during the six decades, such as abandonment of traditional practices and large-scale introduction of forest management oriented towards high volume production, led to continuously denser forests and thereby reduced the oak regeneration niche. In addition, the impact of changed game management was evident. This was particularly clear from a natural experiment on Gotland, a large island free of deer until roe deer were introduced in the late 20th century, at which point oak regeneration began a steep decline. At the stand level, natural oak regeneration could be expected to mainly occur in pulses after disturbance events, followed by a period of low regeneration success as the cohort ages. However, at a landscape scale one would expect a mix of successional stages that would even out such demographic patterns. A prolonged period of low regeneration at a landscape scale will eventually lead to a large gap in the oak size distribution as was observed in this study. This could eventually hurt the many species dependent on old and large oak trees. Active management to restore the oak regeneration niche, i.e. forest habitats with more light and less browsing pressure, therefore seems essential. The latter includes developing strategies that manage both deer populations and their available food across landscapes. Our study is the first to link oak regeneration failure to long-term changes in land use and increased deer populations at a landscape scale in this region. Furthermore, our study show how historical data can clarify confounded processes impacting long-lived forest species.
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| 14. |
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| 15. |
- Villarroel, Beatriz, et al.
(författare)
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Launching the VASCO Citizen Science Project
- 2022
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Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 8:11, s. 561-
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Tidskriftsartikel (refereegranskat)abstract
- The Vanishing & Appearing Sources during a Century of Observations (VASCO) project investigates astronomical surveys spanning a time interval of 70 years, searching for unusual and exotic transients. We present herein the VASCO Citizen Science Project, which can identify unusual candidates driven by three different approaches: hypothesis, exploratory, and machine learning, which is particularly useful for SETI searches. To address the big data challenge, VASCO combines three methods: the Virtual Observatory, user-aided machine learning, and visual inspection through citizen science. Here we demonstrate the citizen science project and its improved candidate selection process, and we give a progress report. We also present the VASCO citizen science network led by amateur astronomy associations mainly located in Algeria, Cameroon, and Nigeria. At the moment of writing, the citizen science project has carefully examined 15,593 candidate image pairs in the data (ca. 10% of the candidates), and has so far identified 798 objects classified as "vanished". The most interesting candidates will be followed up with optical and infrared imaging, together with the observations by the most potent radio telescopes.
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| 16. |
- Wieloch, Tadeusz, et al.
(författare)
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Protein phosphorylation and the regulation of mRNA translation following cerebral ischemia
- 1993. - C
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Ingår i: Neurobiology of Ischemic Brain Damage. - 0079-6123. - 9780444896032 ; 96, s. 179-191
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Bokkapitel (refereegranskat)abstract
- This chapter discusses the changes in protein phosphorylation following ischemia, with particular reference to the regulation of the initiation of protein synthesis. Transient cerebral ischemia seems to induce a post-ischemic imbalance between protein kinase and protein phosphatase activities, leading to a net dephosphorylation of proteins in the vulnerable neurons. This imbalance may lead to the persistent changes in processes crucial for neuronal survival such as post-ischemic protein synthesis. The depression of protein synthesis after an ischemic insult most probably is because of a decreased guanine nucleotide exchange factor (GEF) activity, leading to a limited availability of eukaryotic initiation factors (eIF-2) for initiation complex formation. The inhibition of GEF activity in the vulnerable regions could in turn be because of dephosphorylation of GEF, possibly because of tyrosine phosphatase activation and a decreased casein kinase II activity. Post-ischemic inhibition of protein kinase C and calcium calmodulin kinase II may in addition depress eIF-4 activity leading to a selective translation of mRNA such as heat shock mRNA.
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