| 1. |
- Gustafsson, Erika, et al.
(författare)
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Directed evolution of chemotaxis inhibitory protein of Staphylococcus aureus generates biologically functional variants with reduced interaction with human antibodies
- 2010
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Ingår i: Protein Engineering Design & Selection. - : Oxford University Press (OUP). - 1741-0126 .- 1741-0134. ; 23:2, s. 91-101
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Tidskriftsartikel (refereegranskat)abstract
- Chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) is a protein that binds and blocks the C5a receptor (C5aR) and formylated peptide receptor, thereby inhibiting the immune cell recruitment associated with inflammation. If CHIPS was less reactive with existing human antibodies, it would be a promising anti-inflammatory drug candidate. Therefore, we applied directed evolution and computational/rational design to the CHIPS gene in order to generate new CHIPS variants displaying lower interaction with human IgG, yet retaining biological function. The optimization was performed in four rounds: one round of random mutagenesis to add diversity into the CHIPS gene and three rounds of DNA recombination by Fragment INduced Diversity (FIND((R))). Every round was screened by phage selection and/or ELISA for decreased interaction with human IgG and retained C5aR binding. The mean binding of human anti-CHIPS IgG decreased with every round of evolution. For further optimization, new amino acid substitutions were introduced by rational design, based on the mutations identified during directed evolution. Finally, seven CHIPS variants with low interaction with human IgG and retained C5aR blocking capacity could be identified.
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| 2. |
- Larsson, Jimmy, et al.
(författare)
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Nuclear receptor binding protein 2 is induced during neural progenitor differentiation and affects cell survival
- 2008
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Ingår i: Molecular and Cellular Neuroscience. - : Elsevier BV. - 1044-7431 .- 1095-9327. ; 39:1, s. 32-9
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Tidskriftsartikel (refereegranskat)abstract
- We previously identified nuclear receptor binding protein 2 (NRBP2) in a screen for genes induced by differentiation of neural stem/progenitor cells. Here we show that during embryonic mouse brain development NRBP2 was expressed in the walls of the third and fourth ventricles, and in the hippocampus. In the adult brain, Purkinje cells of the cerebellum and neurons in the CA3 region of the hippocampus were main sites of NRBP2 expression. Analysis of a pediatric medulloblastoma showed that clusters of NRBP2 positive tumor cells co-expressed neurofilament, but not GFAP. Thus, NRBP2 was associated with neuronal differentiation both in normal and malignant brain tissue. We report that NRBP2 is a 55-60 kDa protein with mainly cytoplasmic location. In vitro, NRBP2 protein levels increased as neural stem/progenitor cells differentiated, and its down regulation by siRNA rendered neural progenitor cells more vulnerable to apoptosis. NRBP2 has no previously assigned function and our studies suggest a role for NRBP2 in neural progenitor cell survival.
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| 3. |
- Bergemalm, Daniel, 1977-, et al.
(författare)
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Changes in the spinal cord proteome of an amyotrophic lateral sclerosis murine model determined by differential in-gel electrophoresis
- 2009
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Ingår i: Molecular and cellular proteomics. - : The American Society for Biochemistry and Molecular Biology,Inc. - 1535-9484. ; 8:6, s. 1306-1317
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Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by loss of motor neurons resulting in progressive paralysis. To date, more than 140 different mutations in the gene encoding CuZn-superoxide dismutase (SOD1) have been associated with ALS. Several transgenic murine models exist in which various mutant SOD1s are expressed. We have used differential in-gel electrophoresis (DIGE) to analyze the changes in the spinal cord proteome induced by expression of the unstable SOD1 truncation mutant G127insTGGG (G127X) in mice. Unlike mutants used in most other models, G127X lacks SOD activity and is present at low levels, thus reducing the risk of overexpression artifacts. The mice were analyzed at their peak body weights, just before onset of symptoms. Variable importance plot (VIP) analysis showed that 420 of 1,800 detected protein spots contributed significantly to the differences between the groups. By MALDI-TOF MS analysis, 54 proteins were identified. One spot was found to be a covalently linked mutant SOD1 dimer, apparently analogous to SOD1 immunoreactive bands migrating at double the molecular weight of SOD1 monomers previously detected in humans and mice carrying mutant SOD1s and in sporadic ALS cases. Analyses of affected functional pathways, and the subcellular representation of alterations suggest that the toxicity exerted by mutant SODs induces oxidative stress and affects mitochondria, cellular assembly/organization, and protein degradation.
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| 4. |
- Bergemalm, Daniel, et al.
(författare)
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Superoxide dismutase-1 and other proteins in inclusions from transgenic amyotrophic lateral sclerosis model mice
- 2010
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 114:2, s. 408-418
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Tidskriftsartikel (refereegranskat)abstract
- Mutant superoxide dismutase-1 (SOD1) causes amyotrophic lateral sclerosis (ALS) through a cytotoxic mechanism of unknown nature. A hallmark in ALS patients and transgenic mouse models carrying human SOD1 (hSOD1) mutations are hSOD1-immunoreactive inclusions in spinal cord ventral horns. The hSOD1 inclusions may block essential cellular functions or cause toxicity through sequestering of other proteins. Inclusions from four different transgenic mouse models were examined after density gradient ultracentrifugation. The inclusions are complex structures with heterogeneous densities and are disrupted by detergents. The aggregated hSOD1 was mainly composed of subunits that lacked the native stabilizing intra-subunit disulfide bond. A proportion of subunits formed hSOD1 oligomers or was bound to other proteins through disulfide bonds. Dense inclusions could be isolated and the protein composition was analyzed using proteomic techniques. Mutant hSOD1 accounted for half of the protein. Ten other proteins were identified. Two were cytoplasmic chaperones, four were cytoskeletal proteins, and 4 were proteins that normally reside in the endoplasmic reticulum (ER). The presence of ER proteins in inclusions containing the primarily cytosolic hSOD1 further supports the notion that ER stress is involved in ALS.
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| 5. |
- Bergström, Tobias, et al.
(författare)
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Developmentally regulated collagen/integrin interactions confer adhesive properties to early postnatal neural stem cells
- 2014
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - : Elsevier BV. - 0304-4165 .- 1872-8006. ; 1840:8, s. 2526-2532
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Tidskriftsartikel (refereegranskat)abstract
- Background:It is becoming increasingly apparent that the extracellular matrix acts as an important regulator of the neural stem niche. Previously we found that neural stem and progenitor cells (NSPCs) derived from the early postnatal subventricular zone of mice adhere to a collagen/hyaluronan hydrogel, whereas NSPCs from the adult and embryonic brain do not.Methods:To examine the specific adhesive properties of young stem cells in more detail, NSPCs isolated from embryonic, postnatal day 6 (P6), and adult mouse brains were cultured on collagen I.Results:Early postnatal NSPCs formed paxillin-positive focal adhesions on collagen I, and these adhesions could be prevented by an antibody that blocked integrin beta 1. Furthermore, we found the corresponding integrin alpha subunits alpha 2 and alpha 11 levels to be highest at the postnatal stage. Gene ontology analysis of differentially expressed genes showed higher expression of transcripts involved in vasculature development and morphogenesis in P6 stem cells, compared to adult.Conclusions:The ability to interact with the extracellular matrix differs between postnatal and adult NSPCs.General significance:Our observations that the specific adhesive properties of early postnatal NSPCs, which are lost in the adult brain, can be ascribed to the integrin subunits expressed by the former furthering our understanding of the developing neurogenic niche. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.
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| 6. |
- Bivik Stadler, Caroline, 1986-, et al.
(författare)
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Proactive Construction of an Annotated Imaging Database for Artificial Intelligence Training
- 2021
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Ingår i: Journal of digital imaging. - : Springer-Verlag New York. - 0897-1889 .- 1618-727X. ; 34, s. 105-115
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Tidskriftsartikel (refereegranskat)abstract
- Artificial intelligence (AI) holds much promise for enabling highly desired imaging diagnostics improvements. One of the most limiting bottlenecks for the development of useful clinical-grade AI models is the lack of training data. One aspect is the large amount of cases needed and another is the necessity of high-quality ground truth annotation. The aim of the project was to establish and describe the construction of a database with substantial amounts of detail-annotated oncology imaging data from pathology and radiology. A specific objective was to be proactive, that is, to support undefined subsequent AI training across a wide range of tasks, such as detection, quantification, segmentation, and classification, which puts particular focus on the quality and generality of the annotations. The main outcome of this project was the database as such, with a collection of labeled image data from breast, ovary, skin, colon, skeleton, and liver. In addition, this effort also served as an exploration of best practices for further scalability of high-quality image collections, and a main contribution of the study was generic lessons learned regarding how to successfully organize efforts to construct medical imaging databases for AI training, summarized as eight guiding principles covering team, process, and execution aspects.
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| 7. |
- Brännvall, Karin, et al.
(författare)
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Central nervous system stem/progenitor cells form neurons and peripheral glia after transplantation to the dorsal root ganglion.
- 2006
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Ingår i: NeuroReport. - 0959-4965 .- 1473-558X. ; 17:6, s. 623-628
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Tidskriftsartikel (refereegranskat)abstract
- We asked whether neural stem/progenitor cells from the cerebral cortex of E14.5 enhanced green fluorescent protein transgenic mice are able to survive grafting and differentiate in the adult rat dorsal root ganglion. Neurospheres were placed in lumbar dorsal root ganglion cavities after removal of the dorsal root ganglia. Alternatively, dissociated neurospheres were injected into intact dorsal root ganglia. Enhanced green fluorescent protein-positive cells in the dorsal root ganglion cavity were located in clusters and expressed beta-III-tubulin or glial fibrillary acidic protein after 1 month, whereas after 3 months, surviving grafted cells expressed only glial fibrillary acidic protein. In the intact adult DRG, transplanted neural stem/progenitor cells surrounded dorsal root ganglion cells and fibers, and expressed glial but not neuronal markers. These findings show that central nervous system stem/progenitor cells can survive and differentiate into neurons and peripheral glia after xenotransplantation to the adult dorsal root ganglion.
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| 8. |
- Brännvall, Karin, et al.
(författare)
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Enhanced neuronal differentiation in a three-dimensional collagen-hyaluronan matrix
- 2007
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Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 85:10, s. 2138-2146
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Tidskriftsartikel (refereegranskat)abstract
- Efficient 3D cell systems for neuronal induction are needed for future use in tissue regeneration. In this study, we have characterized the ability of neural stem/progenitor cells (NS/PC) to survive, proliferate, and differentiate in a collagen type I-hyaluronan scaffold. Embryonic, postnatal, and adult NS/PC were seeded in the present 3D scaffold and cultured in medium containing epidermal growth factor and fibroblast growth factor-2, a condition that stimulates NS/PC proliferation. Progenitor cells from the embryonic brain had the highest proliferation rate, and adult cells the lowest, indicating a difference in mitogenic responsiveness. NS/PC from postnatal stages down-regulated nestin expression more rapidly than both embryonic and adult NS/PC, indicating a faster differentiation process. After 6 days of differentiation in the 3D scaffold, NS/PC from the postnatal brain had generated up to 70% neurons, compared with 14% in 2D. NS/PC from other ages gave rise to approximately the same proportion of neurons in 3D as in 2D (9-26% depending on the source for NS/PC). In the postnatal NS/PC cultures, the majority of III-tubulin-positive cells expressed glutamate, -aminobutyric acid, and synapsin I after 11 days of differentiation, indicating differentiation to mature neurons. Here we report that postnatal NS/PC survive, proliferate, and efficiently form synapsin I-positive neurons in a biocompatible hydrogel.
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| 9. |
- Brännvall, Karin, et al.
(författare)
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Environmental cues from CNS, PNS, and ENS cells regulate CNS progenitor differentiation
- 2008
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Ingår i: NeuroReport. - 0959-4965 .- 1473-558X. ; 19:13, s. 1283-9
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Tidskriftsartikel (refereegranskat)abstract
- Cellular origin and environmental cues regulate stem cell fate determination. Neuroepithelial stem cells form the central nervous system (CNS), whereas neural crest stem cells generate the peripheral (PNS) and enteric nervous system (ENS). CNS neural stem/progenitor cell (NSPC) fate determination was investigated in combination with dissociated cultures or conditioned media from CNS, PNS, or ENS. Cells or media from ENS or PNS cultures efficiently promoted NSPC differentiation into neurons, glia, and smooth muscle cells with a similar morphology as the feeder culture. Together with CNS cells or its conditioned medium, NSPC differentiation was partly inhibited and cells remained immature. Here, we demonstrate that secreted factors from the environment can influence CNS progenitor cells to choose a PNS-like cell fate.
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| 10. |
- Erlandsson, Anna, et al.
(författare)
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Autocrine/Paracrine platelet-derived growth factor regulates proliferation of neural progenitor cells
- 2006
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Ingår i: Cancer Research. - 0008-5472 .- 1538-7445. ; 66:16, s. 8042-8048
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Tidskriftsartikel (refereegranskat)abstract
- Growth factors play an important role in regulating neural stem cell proliferation and differentiation. This study shows that platelet-derived growth factor (PDGF) induces a partial differentiation of neural stem/progenitor cells (NSPCs) in the absence of other mitogens in vitro. NSPCs thus acquire an immature morphology and display markers for both neurons and glia. In addition, these cells do not readily mature in the absence of further stimuli. When NSPC cultures treated with PDGF were exposed to additional differentiation factors, however, the differentiation proceeded into neurons, astrocytes, and oligodendrocytes. We find that NSPC cultures are endowed with an endogenous PDGF-BB production. The PDGF-BB expression peaks during early differentiation and is present both in cell lysates and in conditioned medium, allowing for autocrine as well as paracrine signaling. When the NSPC-derived PDGF was inhibited, progenitor cell numbers decreased, showing that PDGF is involved in NSPC expansion. Addition of a PDGF receptor (PDGFR) inhibitor resulted in a more rapid differentiation. Neurons and oligodendrocytes appeared earlier and had more elaborate processes than in control cultures where endogenous PDGFR signaling was not blocked. Our observations point to PDGF as an inducer of partial differentiation of NSPC that also sustains progenitor cell division. Such an intermediate stage in stem cell differentiation is of relevance for the understanding of brain tumor development because autocrine PDGF stimulation is believed to drive malignant conversion of central nervous system progenitor cells.
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