| 2241. |
- Persson, Carina, 1964, et al.
(författare)
-
Greening of the brown-dwarf desert EPIC 212036875b: a 51 M-J object in a 5-day orbit around an F7V star
- 2019
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 628
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Although more than 2000 brown dwarfs have been detected to date, mainly from direct imaging, their characterisation is difficult due to their faintness and model-dependent results. In the case of transiting brown dwarfs, however, it is possible to make direct high-precision observations. Aims. Our aim is to investigate the nature and formation of brown dwarfs by adding a new well-characterised object, in terms of its mass, radius and bulk density, to the currently small sample of less than 20 transiting brown dwarfs. Methods. One brown dwarf candidate was found by the KESPRINT consortium when searching for exoplanets in the K2 space mission Campaign 16 field. We combined the K2 photometric data with a series of multicolour photometric observations, imaging, and radial velocity measurements to rule out false positive scenarios and to determine the fundamental properties of the system. Results. We report the discovery and characterisation of a transiting brown dwarf in a 5.17-day eccentric orbit around the slightly evolved F7V star EPIC 212036875. We find a stellar mass of 1.15 +/- 0.08 M-circle dot, a stellar radius of 1.41 +/- 0.05 R-circle dot, and an age of 5.1 +/- 0.9 Gyr. The mass and radius of the companion brown dwarf are 51 +/- 2 M-J and 0.83 +/- 0.03 R-J, respectively, corresponding to a mean density of 108(-13)(+15) g cm(-3). Conclusions. EPIC 212036875 b is a rare object that resides in the brown-dwarf desert. In the mass-density diagram for planets, brown dwarfs, and stars, we find that all giant planets and brown dwarfs follow the same trend from similar to 0.3 M-J to the turn-over to hydrogen burning stars at similar to 73 M-J. EPIC 212036875 b falls close to the theoretical model for mature H/He dominated objects in this diagram as determined by interior structure models. We argue that EPIC 212036875 b formed via gravitational disc instabilities in the outer part of the disc, followed by a quick migration. Orbital tidal circularisation may have started early in its history for a brief period when the brown dwarf's radius was larger. The lack of spin-orbit synchronisation points to a weak stellar dissipation parameter (Q(star)' greater than or similar to 10(8)), which implies a circularisation timescale of greater than or similar to 23 Gyr, or suggests an interaction between the magnetic and tidal forces of the star and the brown dwarf.
|
|
| 2242. |
- Pettersson, B. M. Fredrik, et al.
(författare)
-
Comparative Sigma Factor-mRNA Levels in Mycobacterium marinum under Stress Conditions and during Host Infection
- 2015
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:10
-
Tidskriftsartikel (refereegranskat)abstract
- We have used RNASeq and qRT-PCR to study mRNA levels for all s-factors in different Mycobacterium marinum strains under various growth and stress conditions. We also studied their levels in M. marinum from infected fish and mosquito larvae. The annotated s-factors were expressed and transcripts varied in relation to growth and stress conditions. Some were highly abundant such as sigA, sigB, sigC, sigD, sigE and sigH while others were not. The s-factor mRNA profiles were similar after heat stress, during infection of fish and mosquito larvae. The similarity also applies to some of the known heat shock genes such as the a-crystallin gene. Therefore, it seems probable that the physiological state of M. marinum is similar when exposed to these different conditions. Moreover, the mosquito larvae data suggest that this is the state that the fish encounter when infected, at least with respect to s-factor mRNA levels. Comparative genomic analysis of s-factor gene localizations in three M. marinum strains and Mycobacterium tuberculosis H37Rv revealed chromosomal rearrangements that changed the localization of especially sigA, sigB, sigD, sigE, sigF and sigJ after the divergence of these two species. This may explain the variation in species-specific expression upon exposure to different growth conditions.
|
|
| 2243. |
|
|
| 2244. |
|
|
| 2245. |
- Pfeiffer, D., et al.
(författare)
-
Genetic Imbalance Is Associated With Functional Outcome After Ischemic Stroke
- 2019
-
Ingår i: Stroke. - : Ovid Technologies (Wolters Kluwer Health). - 0039-2499 .- 1524-4628. ; 50:2, s. 298-304
-
Tidskriftsartikel (refereegranskat)abstract
- Background and Purpose-We sought to explore the effect of genetic imbalance on functional outcome after ischemic stroke (IS). Methods-Copy number variation was identified in high-density single-nucleotide polymorphism microarray data of IS patients from the CADISP (Cervical Artery Dissection and Ischemic Stroke Patients) and SiGN (Stroke Genetics Network)/ GISCOME (Genetics of Ischaemic Stroke Functional Outcome) networks. Genetic imbalance, defined as total number of protein-coding genes affected by copy number variations in an individual, was compared between patients with favorable (modified Rankin Scale score of 0-2) and unfavorable (modified Rankin Scale score of = 3) outcome after 3 months. Subgroup analyses were confined to patients with imbalance affecting ohnologs-a class of dose-sensitive genes, or to those with imbalance not affecting ohnologs. The association of imbalance with outcome was analyzed by logistic regression analysis, adjusted for age, sex, stroke subtype, stroke severity, and ancestry. Results-The study sample comprised 816 CADISP patients (age 44.2 +/- 10.3 years) and 2498 SiGN/GISCOME patients (age 67.7 +/- 14.2 years). Outcome was unfavorable in 122 CADISP and 889 SiGN/GISCOME patients. Multivariate logistic regression analysis revealed that increased genetic imbalance was associated with less favorable outcome in both samples (CADISP: P=0.0007; odds ratio=0.89; 95% CI, 0.82-0.95 and SiGN/GISCOME: P=0.0036; odds ratio=0.94; 95% CI, 0.91-0.98). The association was independent of age, sex, stroke severity on admission, stroke subtype, and ancestry. On subgroup analysis, imbalance affecting ohnologs was associated with outcome (CADISP: odds ratio=0.88; 95% CI, 0.80-0.95 and SiGN/GISCOME: odds ratio=0.93; 95% CI, 0.89-0.98) whereas imbalance without ohnologs lacked such an association. Conclusions-Increased genetic imbalance was associated with poorer functional outcome after IS in both study populations. Subgroup analysis revealed that this association was driven by presence of ohnologs in the respective copy number variations, suggesting a causal role of the deleterious effects of genetic imbalance.
|
|
| 2246. |
- Philipson, Ola, et al.
(författare)
-
A highly insoluble state of Abeta similar to that of Alzheimer's disease brain is found in Arctic APP transgenic mice.
- 2009
-
Ingår i: Neurobiology of aging. - : Elsevier BV. - 1558-1497 .- 0197-4580. ; 30:9, s. 1393-405
-
Tidskriftsartikel (refereegranskat)abstract
- Amyloid-beta (Abeta) is a major drug target in Alzheimer's disease. Here, we demonstrate that deposited Abeta is SDS insoluble in tgAPP-ArcSwe, a transgenic mouse model harboring the Arctic (E693G) and Swedish (KM670/671NL) APP mutations. Formic acid was needed to extract the majority of deposited Abeta in both tgAPP-ArcSwe and Alzheimer's disease brain, but not in a commonly used type of mouse model with the Swedish mutation alone. Interestingly, the insoluble state of Arctic Abeta was determined early on and did not gradually evolve with time. In tgAPP-ArcSwe, Abeta plaques displayed a patchy morphology with bundles of Abeta fibrils, whereas amyloid cores in tgAPP-Swe were circular with radiating fibrils. Amyloid was more densely stacked in tgAPP-ArcSwe, as demonstrated with a conformation sensitive probe. A reduced increase in plasma Abeta was observed following acute administration of an Abeta antibody in tgAPP-ArcSwe, results that might imply reduced brain to plasma Abeta efflux. TgAPP-ArcSwe, with its insoluble state of deposited Abeta, could serve as a complementary model to better predict the outcome of clinical trials.
|
|
| 2247. |
- Philipson, Ola, et al.
(författare)
-
The Arctic amyloid-β precursor protein (AβPP) mutation results in distinct plaques and accumulation of N- and C-truncated Aβ
- 2012
-
Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 33:5, s. 1010.e1-1010.e13
-
Tidskriftsartikel (refereegranskat)abstract
- The Arctic (p. E693G) mutation in the amyloid-β precursor protein (AβPP) facilitates amyloid-β (Aβ) protofibril formation and generates clinical symptoms of Alzheimer's disease (AD). Here, molecular details of Aβ in post mortem brain were investigated with biochemical and morphological techniques. The basic structure of Arctic plaques resembled cotton wool plaques. However, they appeared ring-formed with Aβ42-specific antibodies, but were actually targetoid, since the periphery and center of many parenchymal Aβ deposits stained differently with mid-domain, N- and C-terminal Aβ antibodies. Aβ fibrils were similar in shape, albeit shorter than in sporadic AD brain, when examined by electron microscopy. Aβwild-type and Aβarctic codeposited and parenchymal deposits were highly enriched in both N- and C-terminally truncated Aβ. In contrast, cerebral amyloid angiopathy (CAA) contained a substantial amount of Aβ1-40. The absence of plaques with cores of fibrillary Aβ might be due to the scarcity of full-length Aβ, although other mechanisms could be involved. Our findings are discussed in relation to mechanisms and relevance of amyloid formation and to the clinical features of AD.
|
|
| 2248. |
- Potapov, Anton M., et al.
(författare)
-
Globally invariant metabolism but density-diversity mismatch in springtails
- 2023
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning.
|
|
| 2249. |
- Poteser, M, et al.
(författare)
-
Time Trends of Acrylamide Exposure in Europe: Combined Analysis of Published Reports and Current HBM4EU Studies
- 2022
-
Ingår i: Toxics. - : MDPI AG. - 2305-6304. ; 10:8
-
Tidskriftsartikel (refereegranskat)abstract
- More than 20 years ago, acrylamide was added to the list of potential carcinogens found in many common dietary products and tobacco smoke. Consequently, human biomonitoring studies investigating exposure to acrylamide in the form of adducts in blood and metabolites in urine have been performed to obtain data on the actual burden in different populations of the world and in Europe. Recognizing the related health risk, the European Commission responded with measures to curb the acrylamide content in food products. In 2017, a trans-European human biomonitoring project (HBM4EU) was started with the aim to investigate exposure to several chemicals, including acrylamide. Here we set out to provide a combined analysis of previous and current European acrylamide biomonitoring study results by harmonizing and integrating different data sources, including HBM4EU aligned studies, with the aim to resolve overall and current time trends of acrylamide exposure in Europe. Data from 10 European countries were included in the analysis, comprising more than 5500 individual samples (3214 children and teenagers, 2293 adults). We utilized linear models as well as a non-linear fit and breakpoint analysis to investigate trends in temporal acrylamide exposure as well as descriptive statistics and statistical tests to validate findings. Our results indicate an overall increase in acrylamide exposure between the years 2001 and 2017. Studies with samples collected after 2018 focusing on adults do not indicate increasing exposure but show declining values. Regional differences appear to affect absolute values, but not the overall time-trend of exposure. As benchmark levels for acrylamide content in food have been adopted in Europe in 2018, our results may imply the effects of these measures, but only indicated for adults, as corresponding data are still missing for children.
|
|
| 2250. |
- Poteser, M, et al.
(författare)
-
Trends of Exposure to Acrylamide as Measured by Urinary Biomarkers Levels within the HBM4EU Biomonitoring Aligned Studies (2000-2021)
- 2022
-
Ingår i: Toxics. - : MDPI AG. - 2305-6304. ; 10:8
-
Tidskriftsartikel (refereegranskat)abstract
- Acrylamide, a substance potentially carcinogenic in humans, represents a very prevalent contaminant in food and is also contained in tobacco smoke. Occupational exposure to higher concentrations of acrylamide was shown to induce neurotoxicity in humans. To minimize related risks for public health, it is vital to obtain data on the actual level of exposure in differently affected segments of the population. To achieve this aim, acrylamide has been added to the list of substances of concern to be investigated in the HBM4EU project, a European initiative to obtain biomonitoring data for a number of pollutants highly relevant for public health. This report summarizes the results obtained for acrylamide, with a focus on time-trends and recent exposure levels, obtained by HBM4EU as well as by associated studies in a total of seven European countries. Mean biomarker levels were compared by sampling year and time-trends were analyzed using linear regression models and an adequate statistical test. An increasing trend of acrylamide biomarker concentrations was found in children for the years 2014–2017, while in adults an overall increase in exposure was found to be not significant for the time period of observation (2000–2021). For smokers, represented by two studies and sampling for, over a total three years, no clear tendency was observed. In conclusion, samples from European countries indicate that average acrylamide exposure still exceeds suggested benchmark levels and may be of specific concern in children. More research is required to confirm trends of declining values observed in most recent years.
|
|
