| 1. |
- Brattås, Per Ludvik, et al.
(författare)
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TRIM28 Controls a Gene Regulatory Network Based on Endogenous Retroviruses in Human Neural Progenitor Cells
- 2017
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 18:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Endogenous retroviruses (ERVs), which make up 8% of the human genome, have been proposed to participate in the control of gene regulatory networks. In this study, we find a region- and developmental stage-specific expression pattern of ERVs in the developing human brain, which is linked to a transcriptional network based on ERVs. We demonstrate that almost 10,000, primarily primate-specific, ERVs act as docking platforms for the co-repressor protein TRIM28 in human neural progenitor cells, which results in the establishment of local heterochromatin. Thereby, TRIM28 represses ERVs and consequently regulates the expression of neighboring genes. These results uncover a gene regulatory network based on ERVs that participates in control of gene expression of protein-coding transcripts important for brain development.
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| 2. |
- Yassin Falk, Daroon, 1982-
(författare)
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Skrivundervisning i grundskolans årskurs 3
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation constitutes an illustration of how writing instruction in elementary school, year three, is conducted. At this stage of schooling, most pupils are assumed to have acquired basic reading and writing skills, and from now on, and increasingly over the years that follow, they are expected to read and write longer texts within different genres and subjects. The aim of this thesis is to study writing lessons that were conducted under the framework of four writing projects in a classroom, and the student-written texts that that resulted thereof. The writing pro-jects are characterised by focus on similar text types, which in my mate-rial includes "the fairy tale", "a letter to the editor", "instructions" and a "factual text". The focus of the study is on the relationship between the learning support offered to the pupils in the classroom and the na-ture of texts that the pupils then write.The research is inspired by ethnographic methodology, and is based on material consisting of field notes, video recordings and student texts. The theoretical framework assumes a socio-cultural view of learning and a dialogical view of text and writing. The teaching practices are studied on the basis of how they are built up by different chains of activities (reading, conversation and writing). Particular attention is paid to which text dimensions are addressed in classroom conversations: content, form or function. The pupils’ texts are analysed on the basis of their macro structure, and the analysis builds on the concept of "text activity".On an overall level, the results point to writing being a social activity, which is also closely interconnected to reading, and above all dialogue and conversation. The writing instruction offered to the students is also characterized by a broad view of what literacy is about. The study points out the value of versatile learning support, where the function, form and content of texts, in relation to the learning goals, are made explicit in the teaching. An important result is that the functional dimension of writing, in particular, favours writing development. On a more general level, the study raises the question of which literacy skills can and should be pro-moted by writing education in the early primary school years.
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| 3. |
- Backman, Samuel, et al.
(författare)
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Global DNA Methylation Analysis Identifies Two Discrete clusters of Pheochromocytoma with Distinct Genomic and Genetic Alterations
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Pheochromocytomas and paragangliomas (PPGLs) are rare and frequently heritable neural-crest derived tumours arising from the adrenal medulla or extra-adrenal chromaffin cells respectively. The majority of PPGL tumours are benign and do not recur with distant metastases. However, a sizeable fraction of these tumours secrete vasoactive catecholamines into the circulation causing a variety of symptoms including hypertension, palpitations and diaphoresis. The genetic landscape of PPGL has been well characterized and more than a dozen genes have been described as recurrently mutated. Recent studies of DNA-methylation have revealed distinct clusters of PPGL that share DNA methylation patterns and driver mutations, as well as identified potential biomarkers for malignancy. However, these findings have not been adequately validated in independent cohorts. In this study we use an array-based genome-wide approach to study the methylome of 39 PPGL and 4 normal adrenal medullae. We identified two distinct clusters of tumours characterized by different methylation patterns and different driver mutations. Moreover, we identify genes that are differentially methylated between tumour subcategories, and between tumours and normal tissue.
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| 4. |
- Falk, Anders, et al.
(författare)
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Reliability of the impression replica technique
- 2015
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Ingår i: International Journal of Prosthodontics. - : Quintessence. - 0893-2174 .- 1139-9791. ; 28:2, s. 179-180
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the reliability of the impression replica technique with a four-unit zirconia fixed dental prosthesis (FOP). Marginal and internal fit were measured by repeatedly placing the FDP on an epoxy cast using light-body silicone material corresponding to cement. All measured marginal and internal fit points showed varying values. The greatest variations were seen at the most distal margin (33 mu m) and at the distal abutment of the FDP (77 mu m). The results showed that the technique gives moderate variations and is a useful method to evaluate marginal and internal fit.
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| 5. |
- Falk, Anders, et al.
(författare)
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Reliability of the Impression Replica Technique
- 2015
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Ingår i: International Journal of Prosthodontics. - 0893-2174 .- 1139-9791. ; 28:2, s. 179-180
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the reliability of the impression replica technique with a four-unit zirconia fixed dental prosthesis (FOP). Marginal and internal fit were measured by repeatedly placing the FDP on an epoxy cast using light-body silicone material corresponding to cement. All measured marginal and internal fit points showed varying values. The greatest variations were seen at the most distal margin (33 mu m) and at the distal abutment of the FDP (77 mu m). The results showed that the technique gives moderate variations and is a useful method to evaluate marginal and internal fit.
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| 6. |
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| 7. |
- Falk Windisch, Hannes, 1984, et al.
(författare)
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Determination of the oxide scale growth mechanism using 18O-tracer experiments in combination with Transmission Electron Microscopy and nanoscale Secondary Ion Mass Spectrometry
- 2018
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803. ; 136, s. 128-133
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Tidskriftsartikel (refereegranskat)abstract
- Two-stage 18 O 2 / 16 O 2 exposures can be used to investigate the effect that alloying elements, secondary phases, or surface treatments have on the high temperature oxidation behaviour of certain materials. During subsequent exposures to 16 O 2 - and 18 O 2 -rich atmospheres, 16 O- and 18 O-rich layers are formed. Analysis of the layers using Seco ndary Ion Mass Spectrometry (SIMS) depth profiling allows for conclusions to be drawn about the oxide scale growth mechanism. The conclusions are, however, not entirely unambiguous due to the limited lateral resolution of the technology. Rough surface topography and the thickness variation of the oxide scale over the analysed volume add to the ambiguity of the findings. In this study, an Fe-20%Cr alloy was exposed to both 18 O- and 16 O-rich environments at 850 °C. Two methods were used to analyse the thermally grown Cr 2 O 3 scale: (1) traditional SIMS depth profiling and (2) preparation of a cross-sectional lamellae for Transmission Electron Microscopy (TEM), which, subsequently, was analysed in a NanoSIMS. The NanoSIMS 16 O and 18 O elemental maps were then superimposed on the TEM image. In comparison with traditional SIMS depth profiling, the nanoSIMS elemental maps reveal detailed information about local oxide growth in different parts of an oxide scale. Moreover, a clear 16 O/ 18 O interface can be seen in the nanoSIMS maps, which is not the case in the sputter depth profiles. The findings of this study show that the aforementioned issues associated with sputter depth profiling can be eliminated by mapping a cross-section of an oxide scale using high resolution nanoSIMS.
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| 8. |
- Kollmer, Marius, et al.
(författare)
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Electron tomography reveals the fibril structure and lipid interactions in amyloid deposits
- 2016
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:20, s. 5604-5609
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Tidskriftsartikel (refereegranskat)abstract
- Electron tomography is an increasingly powerful method to study the detailed architecture of macromolecular complexes or cellular structures. Applied to amyloid deposits formed in a cell culture model of systemic amyloid A amyloidosis, we could determine the structural morphology of the fibrils directly in the deposit. The deposited fibrils are arranged in different networks, and depending on the relative fibril orientation, we can distinguish between fibril meshworks, fibril bundles, and amyloid stars. These networks are frequently infiltrated by vesicular lipid inclusions that may originate from the death of the amyloid-forming cells. Our data support the role of nonfibril components for constructing fibril deposits and provide structural views of different types of lipid-fibril interactions.
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| 9. |
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| 10. |
- Lam, Matti, et al.
(författare)
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Single cell analysis of autism patient with bi-allelic NRXN1-alpha deletion reveals skewed fate choice in neural progenitors and impaired neuronal functionality
- 2019
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 383:1
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Tidskriftsartikel (refereegranskat)abstract
- We generated human iPS derived neural stem cells and differentiated cells from healthy control individuals and an individual with autism spectrum disorder carrying bi-allelic NRXN1-alpha deletion. We investigated the expression of NRXN1-alpha during neural induction and neural differentiation and observed a pivotal role for NRXN1-alpha during early neural induction and neuronal differentiation. Single cell RNA-seq pinpointed neural stem cells carrying NRXN1-alpha deletion shifting towards radial glia-like cell identity and revealed higher proportion of differentiated astroglia. Furthermore, neuronal cells carrying NRXN1-alpha deletion were identified as immature by single cell RNA-seq analysis, displayed significant depression in calcium signaling activity and presented impaired maturation action potential profile in neurons investigated with electrophysiology. Our observations propose NRXN1-alpha plays an important role for the efficient establishment of neural stem cells, in neuronal differentiation and in maturation of functional excitatory neuronal cells.
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