Publications
102 results found
McGinty J, Chen L, Kumar S, et al., 2015, Techniques to improve the spatial and temporal resolution in optical projection tomography: Remote focal scanning and time-lapse cell tracking
© OSA 2015. Optical projection tomography is a 3-D imaging approach applicable to transparent samples and model organisms like zebrafish embryos. We present methods to improve the spatial resolution and realize 3-D cell tracking in OPT.
Kelly DJ, Warren SC, Alibhai D, et al., 2015, Automated multiwell fluorescence lifetime imaging for Forster resonance energy transfer assays and high content analysis, ANALYTICAL METHODS, Vol: 7, Pages: 4071-4089, ISSN: 1759-9660
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- Citations: 10
Kone M, Sun G, Ibberson M, et al., 2014, LKB1 and AMPK differentially regulate pancreatic beta-cell identity, Faseb Journal, Vol: 28, Pages: 4972-4985, ISSN: 1530-6860
Fully differentiated pancreatic b cellsare essential for normal glucose homeostasis in mammals.Dedifferentiation of these cells has been suggestedto occur in type 2 diabetes, impairing insulinproduction. Since chronic fuel excess (“glucotoxicity”)is implicated in this process, we sought here to identifythe potential roles in b-cell identity of the tumor suppressorliver kinase B1 (LKB1/STK11) and the downstreamfuel-sensitive kinase, AMP-activated proteinkinase (AMPK). Highly b-cell-restricted deletion ofeach kinase in mice, using an Ins1-controlled Cre, wastherefore followed by physiological, morphometric,and massive parallel sequencing analysis. Loss of LKB1strikingly (2.0–12-fold, E<0.01) increased the expressionof subsets of hepatic (Alb, Iyd, Elovl2) and neuronal(Nptx2, Dlgap2, Cartpt, Pdyn) genes, enhancing glutamatesignaling. These changes were partially recapitulatedby the loss of AMPK, which also up-regulated b-cell“disallowed” genes (Slc16a1, Ldha, Mgst1, Pdgfra) 1.8- to3.4-fold (E<0.01). Correspondingly, targeted promoterswere enriched for neuronal (Zfp206; P51.3310233)and hypoxia-regulated (HIF1; P52.5310216) transcriptionfactors. In summary, LKB1 and AMPK, through onlypartly overlapping mechanisms, maintain b-cell identityby suppressing alternate pathways leading to neuronal,hepatic, and other characteristics. Selective targetingof these enzymes may provide a new approach tomaintaining b-cell function in some forms of diabetes.—Kone,M., Pullen, T. J., Sun, G., Ibberson, M.,Martinez-Sanchez, A., Sayers, S., Nguyen-Tu, M.-S.,Kantor, C., Swisa, A., Dor, Y., Gorman, T., Ferrer, J.,Thorens, B., Reimann, F., Gribble, F., McGinty, J. A.,Chen, L., French, P. M., Birzele, F., Hildebrandt, T.,Uphues, I., Rutter, G. A. LKB1 and AMPK differentiallyregulate pancreatic b-cell identity.
Chen L, Kumar S, Kelly D, et al., 2014, Remote focal scanning optical projection tomography with an electrically tunable lens, Biomedical Optics Express, Vol: 5, Pages: 3367-3375, ISSN: 2156-7085
We describe a remote focal scanning technique for optical projection tomography (OPT) implemented with an electrically tunable lens (ETL) that removes the need to scan the specimen or objective lens. Using a 4× objective lens the average spatial resolution is improved by ∼46% and the light collection efficiency by a factor of ∼6.76, thereby enabling increased acquisition speed and reduced light dose. This convenient implementation is particularly appropriate for lower magnifications and larger sample diameters where axial objective scanning would encounter problems with speed and stability.
Xavier GDS, Mondragon A, Mitchell R, et al., 2014, Defective glucose homeostasis in mice inactivated selectively for Tcf7l2 in the adult beta cell with an Ins1-controlled Cre, 50th EASD Annual Meeting, Publisher: Springer Verlag (Germany), Pages: S151-S151, ISSN: 1432-0428
Dunsby C, Mcginty J, French P, 2014, Multidimensional fluorescence imaging of biological tissue., Biomedical Photonics Handbook, Pages: 531-560, ISBN: 9781439804445
Dunsby C, McGinty J, French P, 2014, Multidimensional fluorescence imaging of biological tissue, Biomedical Photonics Handbook, Second Edition: Fundamentals, Devices, and Techniques, Pages: 531-560, ISBN: 9781420085129
This chapter aims to review multidimensional fluorescence imaging (MDFI) technology and its application to biological tissue, with a particular emphasis on fluorescence lifetime imaging (FLIM) of biological tissue with examples from our work at Imperial College London. Fluorescence imaging is flourishing tremendously, partly driven by advances in laser and detector technology, partly by advances in labeling technologies such as genetically expressed fluorescent proteins, and partly by advances in computational analysis techniques. Increasingly, fluorescence instrumentation is developed to provide more information than just the localization or distribution of specific fluorescent molecules. Often, fluorescence signals are analyzed to provide information on the local fluorophore environment or to contrast different fluorophores in complex mixtures-as often occur in biological tissue. This trend to higher-content fluorescence imaging increasingly exploits MDFI and measurement capabilities with instrumentation that resolves fluorescence lifetime together with other spectroscopic parameters such as excitation and emission wavelength and polarization, providing image information in two or three spatial dimensions as well as with respect to elapsed time (Figure 18.1). However, caution should be exercised when acquiring such MDFI since photobleaching or experimental considerations usually impose a limited photon budget and/or a maximum image acquisition time and also present significant challenges with respect to data analysis and data management. These considerations are particularly important for real-time clinical diagnostic applications, for higher-throughput assays, and for the investigation of dynamic biological systems (Figure 18.1).
Marcu L, French PMW, Elson DS, 2014, Preface, ISBN: 9781439861677
Wide-field time-gated fluorescence lifetime imaging (FLIM) essentially entails illuminating a sample with an ultrashort pulse of excitation radiation and sampling the resulting time varying fluorescence “image” following excitation by acquiring a series of gated fluorescence intensity images recorded at different relative delays with respect to the excitation pulse. This is represented schematically in Figure 8.1. In the simplest case, a map of the mean fluorescence decay times across the field of view is obtained. If the sampling of the fluorescence decay profiles is appropriately detailed, then the entire fluorescence decay profile for each image pixel can be acquired, and the resulting data set can be fitted to complex temporal decay models. For example, a double exponential decay model is frequently used to analyze data from Förster resonant energy transfer (FRET) experiments. The acquisition of time-gated fluorescence intensity images requires a 2-D detector, normally a charge-coupled device (CCD) camera, and some kind of fast “shutter” able to sample fluorescence decay profiles on subnanosecond timescales. Such a “shutter” function cannot be provided by mechanical means or yet by electronic circuitry and is typically provided by optical image intensifiers whose gain can be modulated by varying the applied voltage.
Xavier GDS, Bellomo EA, McGinty JA, et al., 2013, Animal Models of GWAS-Identified Type 2 Diabetes Genes, Journal of Diabetes Research, Vol: 2013, ISSN: 2314-6753
More than 65 loci, encoding up to 500 different genes, have been implicated by genome-wide association studies (GWAS) as conferring an increased risk of developing type 2 diabetes (T2D). Whilst mouse models have in the past been central to understanding the mechanisms through which more penetrant risk genes for T2D, for example, those responsible for neonatal or maturity-onset diabetes of the young, only a few of those identified by GWAS, notably TCF7L2 and ZnT8/SLC30A8, have to date been examined in mouse models. We discuss here the animal models available for the latter genes and provide perspectives for future, higher throughput approaches towards efficiently mining the information provided by human genetics.
Xavier GDS, Mondragon A, Mitchell R, et al., 2013, Defective glucose homeostasis in mice inactivated selectively for <i>Tcf7l2</i> in the adult beta cell with an Ins1-controlled Cre, 49th Annual Meeting of the European-Association-for-the-Study-of-Diabetes (EASD), Publisher: SPRINGER, Pages: S142-S142, ISSN: 0012-186X
Chen L, Andrews N, Kumar S, et al., 2013, Simultaneous angular multiplexing optical projection tomography at shifted focal planes, OPTICS LETTERS, Vol: 38, Pages: 851-853, ISSN: 0146-9592
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- Citations: 16
Coda S, Kelly DJ, Lagarto JL, et al., 2013, Autofluorescence lifetime imaging and metrology for medical research and clinical diagnosis
We report the development of instrumentation to utilise autofluorescence lifetime for the study and diagnosis of disease including cancer and osteoarthritis. ©2013 The Optical Society (OSA).
Xavier GDS, Mondragon A, Sun G, et al., 2012, Abnormal glucose tolerance and insulin secretion in pancreas-specific <i>Tcf7l2</i>-null mice, DIABETOLOGIA, Vol: 55, Pages: 2667-2676, ISSN: 0012-186X
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- Citations: 69
Chen L, McGinty J, Taylor HB, et al., 2012, Incorporation of an experimentally determined MTF for spatial frequency filtering and deconvolution during optical projection tomography reconstruction, OPTICS EXPRESS, Vol: 20, Pages: 7323-7337, ISSN: 1094-4087
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- Citations: 15
Sardini A, Stuckey DW, McGinty J, et al., 2012, In Vivo Investigation of Calpain Activity by Lifetime Imaging of Genetically Encoded FRET Sensors, BIOPHYSICAL JOURNAL, Vol: 102, Pages: 159A-159A, ISSN: 0006-3495
Chen L, McGinty J, Taylor HB, et al., 2012, Improved OPT reconstructions based on the MTF and extension to FLIM-OPT
We demonstrate the improved reconstruction of OPT datasets by incorporating the measured MTF in the reconstruction process. We also extend OPT to FLIM-OPT and demonstrate its use for imaging live zebrafish embryos displaying autofluorescence. © 2012 OSA.
Antkowiak M, Torres-Mapa ML, McGinty J, et al., 2012, Towards gene therapy based on femtosecond optical transfection, BIOPHOTONICS: PHOTONIC SOLUTIONS FOR BETTER HEALTH CARE III, Vol: 8427, ISSN: 0277-786X
Soloviev VY, McGinty J, Stuckey DW, et al., 2011, Förster resonance energy transfer imaging in vivo with approximated radiative transfer equation, Applied Optics, Vol: 50, Pages: 6583-6590
We describe a new light transport model, which was applied to three-dimensional lifetime imaging of Förster resonance energy transfer in mice in vivo. The model is an approximation to the radiative transfer equation and combines light diffusion and ray optics. This approximation is well adopted to wide-field time-gated intensity-based data acquisition. Reconstructed image data are presented and compared with results obtained by using the telegraph equation approximation. The new approach provides improved recovery of absorption and scattering parameters while returning similar values for the fluorescence parameters.
McGinty J, Stuckey DW, Soloviev VY, et al., 2011, In vivo fluorescence lifetime tomography of a FRET probe expressed in mouse, Biomedical Optics Express, Vol: 2, Pages: 1907-1917, ISSN: 2156-7085
Förster resonance energy transfer (FRET) is a powerful biological tool for reading out cell signaling processes. In vivo use of FRET is challenging because of the scattering properties of bulk tissue. By combining diffuse fluorescence tomography with fluorescence lifetime imaging (FLIM), implemented using wide-field time-gated detection of fluorescence excited by ultrashort laser pulses in a tomographic imaging system and applying inverse scattering algorithms, we can reconstruct the three dimensional spatial localization of fluorescence quantum efficiency and lifetime. We demonstrate in vivo spatial mapping of FRET between genetically expressed fluorescent proteins in live mice read out using FLIM. Following transfection by electroporation, mouse hind leg muscles were imaged in vivo and the emission of free donor (eGFP) in the presence of free acceptor (mCherry) could be clearly distinguished from the fluorescence of the donor when directly linked to the acceptor in a tandem (eGFP-mCherry) FRET construct.
McGinty J, Taylor HB, Chen L, et al., 2011, In vivo fluorescence lifetime optical projection tomography, Biomedical Optics Express, Vol: 2, Pages: 1340-1350, ISSN: 2156-7085
We demonstrate the application of fluorescence lifetime optical projection tomography (FLIM-OPT) to in vivo imaging of lysC:GFP transgenic zebrafish embryos (Danio rerio). This method has been applied to unambiguously distinguish between the fluorescent protein (GFP) signal in myeloid cells from background autofluorescence based on the fluorescence lifetime. The combination of FLIM, an inherently ratiometric method, in conjunction with OPT results in a quantitative 3-D tomographic technique that could be used as a robust method for in vivo biological and pharmaceutical research, for example as a readout of Förster resonance energy transfer based interactions.
Kumar S, Alibhai D, Margineanu A, et al., 2011, FLIM FRET technology for drug discovery: automated multiwell-plate high-content analysis, multiplexed readouts and application in situ, ChemPhysChem: a European journal of chemical physics and physical chemistry, Vol: 12, Pages: 609-626, ISSN: 1439-4235
A fluorescence lifetime imaging (FLIM) technology platform intendedto read out changes in Fçrster resonance energy transfer(FRET) efficiency is presented for the study of protein interactionsacross the drug-discovery pipeline. FLIM provides arobust, inherently ratiometric imaging modality for drug discoverythat could allow the same sensor constructs to betranslated from automated cell-based assays through smalltransparent organisms such as zebrafish to mammals. To thisend, an automated FLIM multiwell-plate reader is described forhigh content analysis of fixed and live cells, tomographic FLIMin zebrafish and FLIM FRET of live cells via confocal endomicroscopy.For cell-based assays, an exemplar application readingout protein aggregation using FLIM FRET is presented, andthe potential for multiple simultaneous FLIM (FRET) readoutsin microscopy is illustrated.
Galletly N, McGinty J, Munro I, et al., 2011, Fluorescence lifetime imaging of liver cancer, 107th Annual Meeting of the American-Gastroenterlogical Association, Publisher: W B Saunders Co-Elsevier Inc
Margineanu A, Laine R, Kumar S, et al., 2011, Multiplexed Time Lapse Fluorescence Lifetime Readouts in an Optically Sectioning Time-Gated Imaging Microscope, 55th Annual Meeting of the Biophysical-Society, Publisher: CELL PRESS, Pages: 183-183, ISSN: 0006-3495
McGinty J, Talbot C, Owen D, et al., 2011, Fluorescence Lifetime Imaging Microscopy, Endoscopy and Tomography, Editors: Boas, Pitris, Ramanujam, ISBN: 1420090364
Alibhai D, Kumar S, Kelly D, et al., 2011, An automated wide-field, time-gated, optically sectioning, fluorescence lifetime imaging multiwell plate reader for high-content analysis of protein-protein interactions, Conference on Three-Dimensional and Multidimensional Microscopy - Image Acquisition and Processing XVIII, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
McGinty J, Stuckey D, Laine R, et al., 2010, Time-domain fluorescence lifetime optical projection tomography
We present a platform for measuring the fluorescence lifetime distribution in mesoscopic samples (~0.1-1cm) based on optical projection tomography and time-gated imaging. This is applied to optically cleared embryos expressing a calcium sensing FRET probe. © OSA / BIOMED/DH 2010.
McGinty J, Galletly NP, Dunsby C, et al., 2010, Wide-field fluorescence lifetime imaging of cancer, BIOMEDICAL OPTICS EXPRESS, Vol: 1, Pages: 627-640, ISSN: 2156-7085
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- Citations: 77
Sun G, Tarasov AI, McGinty JA, et al., 2010, LKB1 deletion with the <i>RIP2</i>.<i>Cre</i> transgene modifies pancreatic β-cell morphology and enhances insulin secretion in vivo, AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM, Vol: 298, Pages: E1261-E1273, ISSN: 0193-1849
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- Citations: 56
Sun G, Tarasov AI, McGinty J, et al., 2010, Ablation of AMP-activated protein kinase α1 and α2 from mouse pancreatic beta cells and RIP2.Cre neurons suppresses insulin release in vivo, DIABETOLOGIA, Vol: 53, Pages: 924-936, ISSN: 0012-186X
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- Citations: 80
Soloviev VY, McGinty J, Tahir KB, et al., 2010, Tomographic imaging of fluorescence resonance energy transfer in highly scattering media, SPIE Photonics West, Publisher: SPIE, ISSN: 1605-7422
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