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72 results on '"van den Broek, Sebastiaan P."'

7. Evaluation of detection and tracking performance in imaging systems

Author

Huizinga, Wyke, primary, van Opbroek, Annegreet, additional, Pruim, Raimon H. R., additional, den Hollander, Richard J. M., additional, van den Broek, Sebastiaan P., additional, Schook, Emma S., additional, Schutte, Klamer, additional, van der Stap, Nanda, additional, and Dijk, Judith, additional

Published
2019
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16. Recognition of ships for long-term tracking

Author

van den Broek, Sebastiaan P., additional, Bouma, Henri, additional, Veerman, Henny E. T., additional, Benoist, Koen W., additional, den Hollander, Richard J. M., additional, and Schwering, Piet B. W., additional

Published
2014
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36. SPECT of Transplanted Islets of Langerhans by Dopamine 2 Receptor Targeting in a Rat Model

Author

Willekens, Stefanie M. A., van der Kroon, Inge, Joosten, Lieke, Frielink, Cathelijne, Boerman, Otto C., van den Broek, Sebastiaan A. M. W., Brom, Maarten, and Gotthardt, Martin

Abstract

Pancreatic islet transplantation can be a more permanent treatment for type 1 diabetes compared to daily insulin administration. Quantitative and longitudinal noninvasive imaging of viable transplanted islets might help to further improve this novel therapy. Since islets express dopamine 2 (D2) receptors, they could be visualized by targeting this receptor. Therefore, the D2 receptor antagonist based tracer [125/123I][IBZM] was selected to visualize transplanted islets in a rat model. BZM was radioiodinated, and the labeling was optimized for position 3 of the aromatic ring. [125I]-3-IBZM was characterized in vitro using INS-1 cells and isolated islets. Subsequently, 1,000 islets were transplanted in the calf muscle of WAG/Rij rats and SPECT/CT images were acquired 6 weeks after transplantation. Finally, the graft containing muscle was dissected and analyzed immunohistochemically. Oxidative radioiodination resulted in 3 IBZM isomers with different receptor affinities. The use of 0.6 mg/mL chloramine-T hydrate resulted in high yield formation of predominantly [125I]-3-IBZM, the isomer harboring the highest receptor affinity. The tracer showed D2 receptor mediated binding to isolated islets in vitro. The transplant could be visualized by SPECT 6 weeks after transplantation. The transplants could be localized in the calf muscle and showed insulin and glucagon expression, indicating targeting of viable and functional islets in the transplant. Radioiodination was optimized to produce high yields of [125I]-3-IBZM, the isomer showing optimal D2R binding. Furthermore, [123I]IBZM specifically targets the D2 receptors on transplanted islets. In conclusion, this tracer shows potential for noninvasive in vivo detection of islets grafted in the muscle by D2 receptor targeting.

Published
2016
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37. Cu-catalysed pyrazole synthesis in continuous flowElectronic supplementary information (ESI) available: Experimental procedures, NMR spectra. See DOI: 10.1039/c5cy02247a

Author

Comas-Barceló, Júlia, Blanco-Ania, Daniel, van den Broek, Sebastiaan A. M. W., Nieuwland, Pieter J., Harrity, Joseph P. A., and Rutjes, Floris P. J. T.

Abstract

The synthesis of 1,4-disubstituted pyrazoles viathe cycloaddition reaction of sydnones and terminal alkynes has been achieved employing silica-supported copper catalysts. Furthermore, this methodology has been successfully implemented in continuous flow conditions using prepacked stainless steel cartridges containing the solid-supported copper promoter. Finally, we demonstrate that this synthetic procedure can be successfully scaled up to produce practically useful amounts of pyrazole products within 2–5 hours.

Published
2016
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48. Interfering with UDP-GlcNAc Metabolism and Heparan Sulfate Expression Using a Sugar Analogue Reduces Angiogenesis

Author

van Wijk, Xander M., Thijssen, Victor L., Lawrence, Roger, van den Broek, Sebastiaan A., Dona, Margo, Naidu, Natasha, Oosterhof, Arie, van de Westerlo, Els M., Kusters, Lisanne J., Khaled, Yasmine, Jokela, Tiina A., Nowak-Sliwinska, Patrycja, Kremer, Hannie, Stringer, Sally E., Griffioen, Arjan W., van Wijk, Erwin, van Delft, Floris L., and van Kuppevelt, Toin H.

Abstract

Heparan sulfate (HS), a long linear polysaccharide, is implicated in various steps of tumorigenesis, including angiogenesis. We successfully interfered with HS biosynthesis using a peracetylated 4-deoxy analogue of the HS constituent GlcNAc and studied the compound’s metabolic fate and its effect on angiogenesis. The 4-deoxy analogue was activated intracellularly into UDP-4-deoxy-GlcNAc, and HS expression was inhibited up to ∼96% (IC50= 16 μM). HS chain size was reduced, without detectable incorporation of the 4-deoxy analogue, likely due to reduced levels of UDP-GlcNAc and/or inhibition of glycosyltransferase activity. Comprehensive gene expression analysis revealed reduced expression of genes regulated by HS binding growth factors such as FGF-2 and VEGF. Cellular binding and signaling of these angiogenic factors was inhibited. Microinjection in zebrafish embryos strongly reduced HS biosynthesis, and angiogenesis was inhibited in both zebrafish and chicken model systems. All of these data identify 4-deoxy-GlcNAc as a potent inhibitor of HS synthesis, which hampers pro-angiogenic signaling and neo-vessel formation.

Published
2013
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50. Automatic human action recognition in a scene from visual inputs

Author

Bouma, Henri, Hanckmann, Patrick, Marck, Jan-Willem, Penning, Leo, den Hollander, Richard, ten Hove, Johan-Martijn, van den Broek, Sebastiaan, Schutte, Klamer, and Burghouts, Gertjan

Abstract

Surveillance is normally performed by humans, since it requires visual intelligence. However, this can be dull and dangerous, especially for military operations. Therefore, unmanned autonomous visual-intelligence systems are desired. In this paper, we present a novel system that can recognize human actions, which are relevant to detect operationally significant activity. Central to the system is a break-down of high-level perceptual concepts (verbs) in simpler observable events. The system is trained on 3482 videos and evaluated on 2589 videos from the DARPA Mind's Eye program, with for each video human annotations indicating the presence or absence of 48 different actions. The results show that our system reaches good performance approaching the human average response.

Published
2012
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