| 21. |
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| 22. |
- Alneberg, Johannes, et al.
(författare)
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Ecosystem-wide metagenomic binning enables prediction of ecological niches from genomes
- 2020
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Ingår i: Communications Biology. - : Nature Publishing Group. - 2399-3642. ; 3:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Alneberg et al. conduct metagenomics binning of water samples collected over major environmental gradients in the Baltic Sea. They use machine-learning to predict the placement of genome clusters along niche gradients based on the content of functional genes. The genome encodes the metabolic and functional capabilities of an organism and should be a major determinant of its ecological niche. Yet, it is unknown if the niche can be predicted directly from the genome. Here, we conduct metagenomic binning on 123 water samples spanning major environmental gradients of the Baltic Sea. The resulting 1961 metagenome-assembled genomes represent 352 species-level clusters that correspond to 1/3 of the metagenome sequences of the prokaryotic size-fraction. By using machine-learning, the placement of a genome cluster along various niche gradients (salinity level, depth, size-fraction) could be predicted based solely on its functional genes. The same approach predicted the genomes' placement in a virtual niche-space that captures the highest variation in distribution patterns. The predictions generally outperformed those inferred from phylogenetic information. Our study demonstrates a strong link between genome and ecological niche and provides a conceptual framework for predictive ecology based on genomic data.
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| 23. |
- Anderhag, Per, et al.
(författare)
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Syften och tillfälligheter i högstadie- och gymnasielaborationen : en studie om hur elever handlar i relation till aktivitetens mål
- 2014
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Ingår i: NorDiNa. - : University of Oslo Library. - 1504-4556 .- 1894-1257. ; 10:1, s. 63-76
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Tidskriftsartikel (refereegranskat)abstract
- Purposes and contingencies in the lower and upper secondary school labStudies have shown that students’ awareness of the goals and purposes of the laboratory activity is important for their possibility to participate in and learn from the activity. While practical activities often have been considered to be a central part of science education, relatively few studies have examined laboratory work in situ. In this paper we addressed these issues by examining (a) what purposes are distinguished when students’ work with a laboratory assignment and (b) how these purposes are made continuous with the teacher’s aim with the assignment. The data was based on classroom observations from two ordinary laboratory settings, one from a chemistry class in lower secondary school and one from a physics class in the natural science programme in upper secondary school. Although both student groups acknowledged their teacher’s intentions with the practical and could act towards the more student centered purposes of the activity, e.g. describe what happens with the copper and measure the speed of a small vessel respectively, there were differences regarding the possibilities the students had to act toward the activity’s final aim. The results showed that these factors can be referred to the amount of purposes introduced by the teacher as well as those that arose because of contingences, and the connection of these purposes to students’ prior experiences.
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| 24. |
- Andersson, Anders, et al.
(författare)
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Impact of tobacco smoke on interleukin-16 protein in human airways, lymphoid tissue and T lymphocytes
- 2004
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Ingår i: Clinical and experimental immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 138:1, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- CD4(+) and CD8(+) lymphocytes are mobilized in severe chronic obstructive pulmonary disease (COPD) and the CD8(+) cytokine interleukin (IL)-16 is believed to be important in regulating the recruitment and activity of CD4(+) lymphocytes. In the current study, we examined whether tobacco smoke exerts an impact not only on IL-16 in the lower airways but also in CD4(+) or CD8(+) lymphocytes or in lymphoid tissue. The concentration of IL-16 protein was measured by enzyme-linked immunosorbent assay (ELISA) in concentrated bronchoalveolar lavage fluid (BALF) collected from 33 smokers with chronic bronchitis (CB), eight asymptomatic smokers (AS) and seven healthy never-smokers (NS). The concentrations of IL-16 and soluble IL-2 receptor alpha (sIL-2Ralpha) protein were also measured in conditioned medium from human blood CD4(+) and CD8(+) lymphocytes stimulated with tobacco smoke extract (TSE) in vitro. IL-16 mRNA was assessed in vitro as well, using reverse transcription-polymerase chain reaction (RT-PCR). Finally, the intracellular immunoreactivity for IL-16 protein (IL-16IR) was assessed in six matched pairs of palatine tonsils from smokers and non-smokers. BALF IL-16 was higher in CB and AS than in NS. TSE substantially increased the concentration of IL-16 but not sIL-2Ralpha in conditioned medium from CD4(+) and CD8(+) lymphocytes. There was no corresponding effect on IL-16 mRNA. IL-16IR in tonsils was lower in smokers than in non-smokers. The current findings demonstrate that tobacco smoke exerts a wide impact on the CD8(+) cytokine IL-16, in the airway lumen, in blood CD4(+) and CD8(+) lymphocytes and in lymphoid tissue. The effect on IL-16 release may be selective for preformed IL-16 in CD4(+) lymphocytes. New clinical studies are required to evaluate whether tobacco smoke mobilizes T lymphocytes via IL-16 in the lower airways and whether this mechanism can be targeted in COPD.
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| 25. |
- Andersson, Anders, et al.
(författare)
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Interleukin-16-producing NK cells and T-cells in the blood of tobacco smokers with and without COPD
- 2016
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Ingår i: International Journal of Chronic Obstructive Pulmonary Disease. - : Informa UK Limited. - 1178-2005. ; 11, s. 2245-2258
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Tidskriftsartikel (refereegranskat)abstract
- Background: Long-term exposure to tobacco smoke causes local inflammation in the airways that involves not only innate immune cells, including NK cells, but also adaptive immune cells such as cytotoxic (CD8(+)) and helper (CD4(+)) T-cells. We have previously demonstrated that long-term tobacco smoking increases extracellular concentration of the CD4(+)-recruiting cytokine interleukin (IL)-16 locally in the airways. Here, we hypothesized that tobacco smoking alters IL-16 biology at the systemic level and that this effect involves oxygen free radicals (OFR). Methods: We quantified extracellular IL-16 protein (ELISA) and intracellular IL-16 in NK cells, T-cells, B-cells, and monocytes (flow cytometry) in blood samples from long-term tobacco smokers with and without chronic obstructive pulmonary disease (COPD) and in never-smokers. NK cells from healthy blood donors were stimulated with water-soluble tobacco smoke components (cigarette smoke extract) with or without an OFR scavenger (glutathione) in vitro and followed by quantification of IL-16 protein. Results: The extracellular concentrations of IL-16 protein in blood did not display any substantial differences between groups. Notably, intracellular IL-16 protein was detected in all types of blood leukocytes. All long-term smokers displayed a decrease in this IL-16 among NK cells, irrespective of COPD status. Further, both NK and CD4(+) T-cell concentrations displayed a negative correlation with pack-years. Moreover, cigarette smoke extract caused release of IL-16 protein from NK cells in vitro, and this was not affected by glutathione, in contrast to the decrease in intracellular IL-16, which was prevented by this drug. Conclusion: Long-term exposure to tobacco smoke does not markedly alter extracellular concentrations of IL-16 protein in blood. However, it does decrease the intracellular IL-16 concentrations in blood NK cells, the latter effect involving OFR. Thus, long-term tobacco smoking exerts an impact at the systemic level that involves NK cells; innate immune cells that are critical for host defense against viruses and tumors-conditions that are over-represented among smokers.
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| 26. |
- Andersson, Annika K., et al.
(författare)
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Cytokine-induced PGE2 formation is reduced from iNOS deficient murine islets
- 2004
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Ingår i: Molecular and Cellular Endocrinology. - : Elsevier BV. - 0303-7207 .- 1872-8057. ; 220:1-2, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- Cytokines may be involved in islet destruction during Type 1 diabetes. Exposure to interleukin-1beta (IL-1beta) or IL-1beta plus interferon-gamma (IFN-gamma) of rodent islets induces expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Subsequent formation of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) may impair beta-cell function. Using iNOS deficient (iNOS -/-) islets, we have further investigated the relation between NO formation and PGE(2) induction. We found that iNOS -/- islets responded with a reduced PGE(2) formation following IL-1beta or (IL-1beta + IFN-gamma) treatment compared to wild-type (wt) islets, while COX-2 mRNA or protein content were unchanged. By the addition of an NO donor together with IL-1beta, PGE(2) formation could be stimulated from iNOS -/- islets. We conclude that the lowered capacity of PGE(2) formation observed from cytokine exposed iNOS -/- islets is due to a decreased stimulation of PGE(2) formation by the COX-2 enzyme in the absence of NO, rather then differences in expressed COX-2 protein.
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