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Träfflista för sökning "WFRF:(Ohlin Mathias) "

Sökning: WFRF:(Ohlin Mathias)

  • Resultat 1-10 av 38
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1.
  • Mikus, Maria, et al. (författare)
  • Allergome-wide peptide microarrays enable epitope deconvolution in allergen-specific immunotherapy
  • 2020
  • Ingår i: Journal of Allergy and Clinical Immunology. - : Mosby Inc.. - 0091-6749 .- 1097-6825.
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: The interaction of allergens and allergen-specific IgE initiates the allergic cascade after crosslinking of receptors on effector cells. Antibodies of other isotypes may modulate such a reaction. Receptor crosslinking requires binding of antibodies to multiple epitopes on the allergen. Limited information is available on the complexity of the epitope structure of most allergens. Objectives: We sought to allow description of the complexity of IgE, IgG4, and IgG epitope recognition at a global, allergome-wide level during allergen-specific immunotherapy (AIT). Methods: We generated an allergome-wide microarray comprising 731 allergens in the form of more than 172,000 overlapping 16-mer peptides. Allergen recognition by IgE, IgG4, and IgG was examined in serum samples collected from subjects undergoing AIT against pollen allergy. Results: Extensive induction of linear peptide-specific Phl p 1– and Bet v 1–specific humoral immunity was demonstrated in subjects undergoing a 3-year-long AIT against grass and birch pollen allergy, respectively. Epitope profiles differed between subjects but were largely established already after 1 year of AIT, suggesting that dominant allergen-specific antibody clones remained as important contributors to humoral immunity following their initial establishment during the early phase of AIT. Complex, subject-specific patterns of allergen isoform and group cross-reactivities in the repertoires were observed, patterns that may indicate different levels of protection against different allergen sources. Conclusions: The study highlights the complexity and subject-specific nature of allergen epitopes recognized following AIT. We envisage that epitope deconvolution will be an important aspect of future efforts to describe and analyze the outcomes of AIT in a personalized manner.
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2.
  • Christakou, Athanasia E., et al. (författare)
  • Live cell imaging in a micro-array of acoustic traps facilitates quantification of natural killer cell heterogeneity
  • 2013
  • Ingår i: Integrative Biology. - 1757-9694 .- 1757-9708. ; 5:4, s. 712-719
  • Tidskriftsartikel (refereegranskat)abstract
    • Natural killer (NK) cells kill virus-infected or cancer cells through the release of cytotoxic granules into a tight intercellular contact. NK cell populations comprise individual cells with varying sensitivity to distinct input signals, leading to disparate responses. To resolve this NK cell heterogeneity, we have designed a novel assay based on ultrasound-assisted cell-cell aggregation in a multiwell chip allowing high-resolution time-lapse imaging of one hundred NK-target cell interactions in parallel. Studying human NK cells' ability to kill MHC class I deficient tumor cells, we show that approximately two thirds of the NK cells display cytotoxicity, with some NK cells being particularly active, killing up to six target cells during the assay. We also report that simultaneous interaction with several susceptible target cells increases the cytotoxic responsiveness of NK cells, which could be coupled to a previously unknown regulatory mechanism with implications for NK-mediated tumor elimination.
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3.
  • Christakou, Athanasia, et al. (författare)
  • Ultrasonic three-dimensional on-chip cell culture for dynamic studies of tumor immune surveillance by natural killer cells
  • 2015
  • Ingår i: Lab on a Chip. - : Royal Society of Chemistry. - 1473-0197 .- 1473-0189. ; 15:15, s. 3222-31
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate a simple method for three-dimensional (3D) cell culture controlled by ultrasonic standing waves in a multi-well microplate. The method gently arranges cells in a suspension into a single aggregate in each well of the microplate and, by this, nucleates 3D tissue-like cell growth for culture times between two and seven days. The microplate device is compatible with both high-resolution optical microscopy and maintenance in a standard cell incubator. The result is a scaffold- and coating-free method for 3D cell culture that can be used for controlling the cellular architecture, as well as the cellular and molecular composition of the microenvironment in and around the formed cell structures. We demonstrate the parallel production of one hundred synthetic 3D solid tumors comprising up to thousands of human hepatocellular carcinoma (HCC) HepG2 cells, we characterize the tumor structure by high-resolution optical microscopy, and we monitor the functional behavior of natural killer (NK) cells migrating, docking and interacting with the tumor model during culture. Our results show that the method can be used for determining the collective ability of a given number of NK cells to defeat a solid tumor having a certain size, shape and composition. The ultrasound-based method itself is generic and can meet any demand from applications where it is advantageous to monitor cell culture from production to analysis of 3D tissue or tumor models using microscopy in one single microplate device.
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4.
  • Ohlin, M., et al. (författare)
  • Improved positioning and detectability of microparticles in droplet microfluidics using two-dimensional acoustophoresis
  • 2017
  • Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 0960-1317 .- 1361-6439. ; 27:8
  • Tidskriftsartikel (refereegranskat)abstract
    • We have fabricated a silicon-glass two-phase droplet microfluidic system capable of generating sub 100 μm-sized, ø = (74 ± 2) μm, spherical droplets at rates of up to hundreds of hertz. By implementing a two-dimensional (2D) acoustophoresis particle-positioning method, we show a fourfold improvement in both vertical and lateral particle positioning inside the droplets compared to unactuated operation. The efficiency of the system has been optimized by incorporating aluminum matching layers in the transducer design permitting biocompatible operational temperatures (<37 °C). Furthermore, by using acoustic actuation, (99.8 ± 0.4)% of all encapsulated microparticles can be detected compared to only (79.0 ± 5.1)% for unactuated operation. In our experiments we observed a strong ordering of the microparticles in distinct patterns within the droplet when using 2D acoustophoresis; to explain the origin of these patterns we simulated numerically the fluid flow inside the droplets and compared with the experimental findings.
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5.
  • Ohlin, Mathias, et al. (författare)
  • Influence of acoustic streaming on ultrasonic particle manipulation in a 100-well ring-transducer microplate
  • 2013
  • Ingår i: Journal of Micromechanics and Microengineering. - 0960-1317 .- 1361-6439. ; 23:3, s. 035008-
  • Tidskriftsartikel (refereegranskat)abstract
    • We characterize and quantify the performance of ultrasonic particle aggregation and positioning in a 100-well microplate. We analyze the result when operating a planar ultrasonic ring transducer at different single actuation frequencies in the range 2.20-2.40 MHz, and compare with the result obtained from different schemes of frequency-modulated actuation. Compared to our previously used wedge transducer design, the ring transducer has a larger contact area facing the microplate, resulting in lower temperature increase for a given actuation voltage. Furthermore, we analyze the dynamics of acoustic streaming occurring simultaneously with the particle trapping in the wells of the microplate, and we define an adaptive ultrasonic actuation scheme for optimizing both efficiency and robustness of the method. The device is designed as a tool for ultrasound-mediated cell aggregation and positioning. This is a method for high-resolution optical characterization of time-dependent cellular processes at the level of single cells. In this paper, we demonstrate how to operate our device in order to optimize the scanning time of 3D confocal microscopy with the aim to perform high-resolution time-lapse imaging of cells or cell-cell interactions in a highly parallel manner.
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6.
  • Olofsson, K., et al. (författare)
  • Acoustic formation of multicellular tumor spheroids enabling on-chip functional and structural imaging
  • 2018
  • Ingår i: Lab on a Chip. - : ROYAL SOC CHEMISTRY. - 1473-0197 .- 1473-0189. ; 18:16, s. 2466-2476
  • Tidskriftsartikel (refereegranskat)abstract
    • Understanding the complex 3D tumor microenvironment is important in cancer research. This microenvironment can be modelled in vitro by culturing multicellular tumor spheroids (MCTS). Key challenges when using MCTS in applications such as high-throughput drug screening are overcoming imaging and analytical issues encountered during functional and structural investigations. To address these challenges, we use an ultrasonic standing wave (USW) based MCTS culture platform for parallel formation, staining and imaging of 100 whole MCTS. A protein repellent amphiphilic polymer coating enables flexible production of high quality and unanchored MCTS. This enables high-content multimode analysis based on flow cytometry and in situ optical microscopy. We use HepG2 hepatocellular carcinoma, A498 and ACHN renal carcinoma, and LUTC-2 thyroid carcinoma cell lines to demonstrate (i) the importance of the ultrasound-coating combination, (ii) bright field image based automatic characterization of MTCS, (iii) detailed deep tissue confocal imaging of whole MCTS mounted in a refractive index matching solution, and (iv) single cell functional analysis through flow cytometry of single cell suspensions of disintegrated MTCS. The USW MCTS culture platform is customizable and holds great potential for detailed multimode MCTS analysis in a high-content manner.
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7.
  • Vanherberghen, Bruno, et al. (författare)
  • Ultrasound-controlled cell aggregation in a multi-well chip
  • 2010
  • Ingår i: Lab on a Chip. - 1473-0197 .- 1473-0189. ; 10:20, s. 2727-2732
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate a microplate platform for parallelized manipulation of particles or cells by frequency-modulated ultrasound. The device, consisting of a silicon-glass microchip and a single ultrasonic transducer, enables aggregation, positioning and high-resolution microscopy of cells distributed in an array of 100 microwells centered on the microchip. We characterize the system in terms of temperature control, aggregation and positioning efficiency, and cell viability. We use time-lapse imaging to show that cells continuously exposed to ultrasound are able to divide and remain viable for at least 12 hours inside the device. Thus, the device can be used to induce and maintain aggregation in a parallelized fashion, facilitating long-term microscopy studies of, e.g., cell-cell interactions.
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8.
  • Wiklund, Martin, et al. (författare)
  • Ultrasound-Induced Cell-Cell Interaction Studies in a Multi-Well Microplate
  • 2014
  • Ingår i: Micromachines. - 2072-666X .- 2072-666X. ; 5:1, s. 27-49
  • Forskningsöversikt (refereegranskat)abstract
    • This review describes the use of ultrasound for inducing and retaining cell-cell contact in multi-well microplates combined with live-cell fluorescence microscopy. This platform has been used for studying the interaction between natural killer (NK) cells and cancer cells at the level of individual cells. The review includes basic principles of ultrasonic particle manipulation, design criteria when building a multi-well microplate device for this purpose, biocompatibility aspects, and finally, two examples of biological applications: Dynamic imaging of the inhibitory immune synapse, and studies of the heterogeneity in killing dynamics of NK cells interacting with cancer cells.
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9.
  • Christakou, Athanasia, et al. (författare)
  • Characterization of natural killer cell immune surveillance against solid liver tumors
  • 2015
  • Ingår i: MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences. - : Chemical and Biological Microsystems Society. - 9780979806483 ; , s. 915-917
  • Konferensbidrag (refereegranskat)abstract
    • We demonstrate a method for investigating natural killer (NK) cell aggression against ultrasound-assisted human hepatocellular carcinoma (HCC) HepG2 solid tumors in a multi-well microdevice. We quantify the activity of human primary IL-2 activated NK cells against HepG2 tumors for up to five days and we present the correlation between NK cell numbers versus average tumor volume and final tumor outcome (growth or defeat). We suggest future applications on formation of tumors originated from primary tumors cells and other tumor components as well as primary NK originating from the patient for use in personalized immunotherapy.
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10.
  • Christakou, Athanasia. E., et al. (författare)
  • Aggregation and long-term positioning of cells by ultrasound in a multi-well microchip for high-resolution imaging of the natural killer cell immune synapse
  • 2011
  • Ingår i: 15th International Conference on Miniaturized Systems for Chemistry and Life Sciences 2011, MicroTAS 2011. - 9781618395955 ; , s. 329-331
  • Konferensbidrag (refereegranskat)abstract
    • In this study we investigate the ability of Natural Killer (NK) cells to form ultrasound-mediated intercellular contacts with target cells in a multi-well microdevice by high-resolution confocal-microscopy imaging of inhibitory immune synapses. Furthermore, we compare the NK-Target cell cluster migration with and without ultrasound actuation. Experiments indicate that clusters of cells are positioned and maintained centered in the wells for 17 hours when they are exposed continuously to ultrasound. Our system can be used for both screening high numbers of events in low resolution and also for high resolution imaging of long term cell-cell interactions.
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  • Resultat 1-10 av 38
  • [1]234Nästa

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