Publications
51 results found
Thompson AJ, Hughes M, Anastasova S, et al., 2017, The potential role of optical biopsy in the study and diagnosis of environmental enteric dysfunction, Nature Reviews Gastroenterology and Hepatology, Vol: 14, Pages: 727-738, ISSN: 1759-5045
Environmental enteric dysfunction (EED) is a disease of the small intestine affecting children and adults in low and middle income countries. Arising as a consequence of repeated infections, gut inflammation results in impaired intestinal absorptive and barrier function, leading to poor nutrient uptake and ultimately to stunting and other developmental limitations. Progress towards new biomarkers and interventions for EED is hampered by the practical and ethical difficulties of cross-validation with the gold standard of biopsy and histology. Optical biopsy techniques — which can provide minimally invasive or noninvasive alternatives to biopsy — could offer other routes to validation and could potentially be used as point-of-care tests among the general population. This Consensus Statement identifies and reviews the most promising candidate optical biopsy technologies for applications in EED, critically assesses them against criteria identified for successful deployment in developing world settings, and proposes further lines of enquiry. Importantly, many of the techniques discussed could also be adapted to monitor the impaired intestinal barrier in other settings such as IBD, autoimmune enteropathies, coeliac disease, graft-versus-host disease, small intestinal transplantation or critical care.
Power M, Seneci CA, Thompson AJ, et al., 2017, Modelling & characterization of a compliant tethered microgripper for microsurgical applications, International Conference on Manipulation, Automation and Robotics at Small Scales, MARSS 2017, Publisher: IEEE
The development of microscale surgical tools could pave the way for truly minimally invasive microsurgical procedures. This work demonstrates the application of direct laser writing (DLW) using two-photon polymerization (TPP), a rapid prototyping microfabrication technique, to create a tethered, passively actuated three-dimensional gripper with potential applications in microbiopsy. A microgripper design was devised, modelled and optimized. The gripper was then fabricated and characterized for validation of the theoretical model. The results demonstrate that modelling the behavior of compliant microtools provides a useful approximation for the observed trends and, thus, can be utilized in the design of TPP tools. Future work on the incorporation of viscoelastic material into the model will further improve agreement between the predicted and experimental performance.
Kuimova MK, Mika JT, Thompson AJ, et al., 2016, Measuring the viscosity of the Escherichia coli plasma membrane using molecular rotors, Biophysical Journal, Vol: 111, Pages: 1528-1540, ISSN: 1542-0086
The viscosity is a highly important parameter within the cell membrane, affecting the diffusion ofsmall molecules and, hence, controlling the rates of intra-cellular reactions. There is significantinterest in the direct, quantitative assessment of membrane viscosity. Here we report the use offluorescence lifetime imaging microscopy (FLIM) of the molecular rotor BODIPY C10 in themembranes of live Escherichia coli (E. coli) bacteria to permit direct quantification of the viscosity.Using this approach we investigated the viscosity in live E. coli cells, spheroplasts and liposomesmade from E. coli membrane extracts. For live cells and spheroplasts the viscosity was measured atboth room temperature (23o C) and the E. coli growth temperature (37o C), while the membraneextract liposomes were studied over a range of measurement temperatures (5-40o C). At 37o C werecorded a membrane viscosity in live E. coli cells of 950 cP, which is considerably higher than thatpreviously observed in other live cell membranes (e.g., eukaryotic cells, membranes of Bacillusvegetative cells). Interestingly, this indicates that E. coli cells exhibit a high degree of lipid orderingwithin their liquid-phase plasma membranes.
Thompson AJ, Koziej L, Williams H, et al., 2016, Towards optical fibre based Raman spectroscopy for the detection of surgical site infection, BiOS, SPIE Photonics West, Publisher: SPIE
Surgical site infections (SSIs) are common post-surgical complications that remain significant clinical problems, as they are associated with substantial mortality and morbidity. As such, there is significant interest in the development of minimally invasive techniques that permit early detection of SSIs. To this end, we are applying a compact, clinically deployable Raman spectrometer coupled to an optical fibre probe to the study of bacteria, with the long term goal of using Raman spectroscopy to detect infection in vivo. Our system comprises a 785 nm laser diode for excitation and a commercial (Ocean Optics, Inc.) Raman spectrometer for detection. Here we discuss the design, optimisation and validation of this system, and describe our first experiences interrogating bacterial cells (Escherichia coli) in vitro. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thompson AJ, Herling TW, Kubankova M, et al., 2015, Molecular Rotors Provide Insights into Microscopic Structural Changes During Protein Aggregation., Journal of Physical Chemistry B, Vol: 119, Pages: 10170-10179, ISSN: 1520-6106
Changes in microscopic viscosity represent an important characteristic of structural transitions in soft matter systems. Here we demonstrate the use of molecular rotors to explore the changes in microrheology accompanying the transition of proteins from their soluble states into a gel phase composed of amyloid fibrils. The formation of beta-sheet rich protein aggregates, including amyloid fibrils, is a hallmark of a number of neurodegenerative disorders, and as such, the mechanistic details of this process are actively sought after. In our experiments, molecular rotors report an increase in rigidity of approximately three orders of magnitude during the aggregation reaction. Moreover, phasor analysis of the fluorescence decay signal from the molecular rotors suggests the presence of multiple distinct mechanistic stages during the aggregation process. Our results show that molecular rotors can reveal key microrheological features of protein systems not observable through classical fluorescent probes operating in light switch mode.
Brydegaard M, Thompson AJ, Andersson-Engels S, et al., 2015, Complete parameterization of temporally and spectrally resolved laser induced fluorescence data with applications in bio-photonics, CHEMOMETRICS AND INTELLIGENT LABORATORY SYSTEMS, Vol: 142, Pages: 95-106, ISSN: 0169-7439
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Mika JT, Thompson AJ, Hofkens J, et al., 2015, Measurement of the Viscosity of E. coli Membranes using Molecular Rotors and Flim, 59th Annual Meeting of the Biophysical-Society, Publisher: CELL PRESS, Pages: 542A-542A, ISSN: 0006-3495
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Tang T-YD, Hak CRC, Thompson AJ, et al., 2014, Fatty acid membrane assembly on coacervate microdroplets as a step towards a hybrid protocell model, Nature Chemistry, Vol: 6, Pages: 527-533, ISSN: 1755-4330
Mechanisms of prebiotic compartmentalization are central to providing insights into how protocellular systems emerged on the early Earth. Protocell models are based predominantly on the membrane self-assembly of fatty-acid vesicles, although membrane-free scenarios that involve liquid–liquid microphase separation (coacervation) have also been considered. Here we integrate these alternative models of prebiotic compartmentalization and develop a hybrid protocell model based on the spontaneous self-assembly of a continuous fatty-acid membrane at the surface of preformed coacervate microdroplets prepared from cationic peptides/polyelectrolytes and adenosine triphosphate or oligo/polyribonucleotides. We show that the coacervate-supported membrane is multilamellar, and mediates the selective uptake or exclusion of small and large molecules. The coacervate interior can be disassembled without loss of membrane integrity, and fusion and growth of the hybrid protocells can be induced under conditions of high ionic strength. Our results highlight how notions of membrane-mediated compartmentalization, chemical enrichment and internalized structuration can be integrated in protocell models via simple chemical and physical processes.
Thompson AJ, Tang T-YD, Herling TW, et al., 2014, Quantitative sensing of microviscosity in protocells and amyloid materials using fluorescence lifetime imaging of molecular rotors, Conference on Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues XII, Publisher: SPIE- Society of Photo-optical Instrumentation Engineers, ISSN: 0277-786X
Molecular rotors are fluorophores that have a fluorescence quantum yield that depends upon intermolecular rotation. The fluorescence quantum yield, intensity and lifetime of molecular rotors all vary as functions of viscosity, as high viscosities inhibit intermolecular rotation and cause an increase in the non-radiative decay rate. As such, molecular rotors can be used to probe viscosity on microscopic scales. Here, we apply fluorescence lifetime imaging microscopy (FLIM) to measure the fluorescence lifetimes of three different molecular rotors, in order to determine the microscopic viscosity in two model systems with significant biological interest. First, the constituents of a novel protocell – a model of a prebiotic cell – were studied using the molecular rotors BODIPY C10 and kiton red. Second, amyloid formation was investigated using the molecular rotor Cy3. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Coda S, Thompson AJ, Kennedy GT, et al., 2014, Fluorescence lifetime spectroscopy of tissue autofluorescence in normal and diseased colon measured ex vivo using a fiber-optic probe, Biomedical Optics Express, Vol: 5, Pages: 515-538, ISSN: 2156-7085
We present an ex vivo study of temporally and spectrally resolved autofluorescence in a total of 47 endoscopic excision biopsy/resection specimens from colon, using pulsed excitation laser sources operating at wavelengths of 375 nm and 435 nm. A paired analysis of normal and neoplastic (adenomatous polyp) tissue specimens obtained from the same patient yielded a significant difference in the mean spectrally averaged autofluorescence lifetime −570 ± 740 ps (p = 0.021, n = 12). We also investigated the fluorescence signature of non-neoplastic polyps (n = 6) and inflammatory bowel disease (n = 4) compared to normal tissue in a small number of specimens.
Karim NHA, Mendoza O, Shivalingam A, et al., 2014, Salphen metal complexes as tunable G-quadruplex binders and optical probes, RSC ADVANCES, Vol: 4, Pages: 3355-3363, ISSN: 2046-2069
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- Citations: 51
Thompson AJ, 2013, Developing endoscopic instrumentation and techniques for in vivo fluorescence lifetime imaging and spectroscopy
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).
Coda S, Thompson AJ, Lenz MO, et al., 2012, Sa1609 Fluorescence Lifetime Imaging and Spectroscopy for Label-Free Contrast of Gastrointestinal Diseases, Gastrointestinal Endoscopy, Vol: 75, Pages: AB219-AB220, ISSN: 0016-5107
Thompson AJ, Coda S, Sorensen MB, et al., 2012, In vivo measurements of diffuse reflectance and time-resolved autofluorescence emission spectra of basal cell carcinomas, JOURNAL OF BIOPHOTONICS, Vol: 5, Pages: 240-254, ISSN: 1864-063X
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- Citations: 30
Coda S, Kennedy GT, Thompson A, et al., 2011, FLUORESCENCE LIFETIME IMAGING FOR LABEL-FREE CONTRAST OF GASTROINTESTINAL DISEASES, International School of Physics "Enrico Fermi", Course CLXXXI "Microscopy Applied to Biophotonics"
INTRODUCTION: Autofluorescence (AF) has been used to distinguish between normal and diseased tissue, but its molecular basis is still unclear and making quantitative intensity measurements is challenging. Fluorescence lifetime imaging (FLIM) measures the decay rate of the autofluorescent signal from tissue, providing quantitative AF contrast. FLIM has been recently implemented by our group in three endoscopic instruments consisting of a confocal laser endomicroscope, a wide-field fibre-optic endoscope and a single point fibre-optic probe. FLIM has the potential to report on tissue structure and function in real-time during endoscopy, providing a label-free means to detect the early onset of diseases that cause changes in tissue AF. We are developing these 3 modalities for in vivo clinical application, supported by ex vivo studies on freshly-biopsied/resected GI tissues.AIMS & METHODS: The aim of this work is to translate our FLIM instrumentation from the optical bench to in vivo clinical application. AF from 43 endoscopic samples from different GI sites was excited using a conventional confocal FLIM microscope in the range 405-420nm, which is compatible with our FLIM endoscopes, and which is the range needed to excite a number of important endogenous GI tissue fluorophores such as porphyrins, flavins, collagen and elastin. The samples were collected from patients undergoing endoscopy, transported to the FLIM laboratory to be imaged and then submitted for histopathology. The following disorders were investigated: Barrett’s oesophagus, gastric cancer, ulcerative colitis, Crohn’s disease, adenomatous polyps and colon cancer. The accuracy of FLIM in discriminating dysplastic/cancerous samples from normal tissue has been tested by measuring the Area Under the Curve (AUC).RESULTS: Our preliminary data show that premalignant or neoplastic samples display either shorter or longer fluorescence lifetime than that of normal tissue. Increased lifetime val
Coda S, Kennedy G, Thompson A, et al., 2011, FLUORESCENCE LIFETIME IMAGING OF GASTROINTESTINAL CANCERS, European-Society-for-Medical-Oncology (ESMO) 13th World Congress on Gastrointestinal Cancer, Publisher: OXFORD UNIV PRESS, Pages: v65-v66, ISSN: 0923-7534
Thompson AJ, Paterson C, Neil MAA, et al., 2011, Adaptive phase compensation for ultracompact laser scanning endomicroscopy, OPTICS LETTERS, Vol: 36, Pages: 1707-1709, ISSN: 0146-9592
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- Citations: 68
Coda S, Kennedy GT, Thompson A, et al., 2011, FLUORESCENCE LIFETIME IMAGING FOR LABEL-FREE CONTRAST OF GASTROINTESTINAL DISEASES, Digestive Disease Week, Publisher: Elsevier, ISSN: 0016-5107
INTRODUCTION: Autofluorescence (AF) is a means to distinguish between normal and diseased tissue, but its molecular basis is unclear and intensity-based contrast is often not sufficiently specific. Fluorescence lifetime imaging (FLIM) maps the decay rate of fluorescence emitted from tissue samples, providing quantitative AF contrast. FLIM has been recently implemented by our group in three endoscopic instruments consisting of a confocal laser endomicroscope, a wide-field fibre-optic endoscope and a single point fibre-optic probe. FLIM has the potential to report on tissue structure and function in real-time during endoscopy, providing a label-free means to detect the early onset of diseases that cause changes in tissue AF. We are developing these 3 modalities for in vivo clinical application, supported by ex vivo studies on freshly-biopsied/resected GI tissues.AIMS & METHODS: In this study, autofluorescence from 25 endoscopic samples from different GI sites was excited using a conventional confocal FLIM microscope in the range 405-420nm, which is compatible with our FLIM endoscopes, and which is the range needed to excite a number of important endogenous GI tissue fluorophores such as porphyrins, flavins, collagen and elastin. The samples were collected from patients undergoing endoscopy, transported to the FLIM laboratory to be imaged and then submitted for histopathology. The following diseases were investigated: Barrett’s oesophagus, gastric cancer, ulcerative colitis, adenomatous polyps and colon cancer. ROC curve analysis was used to statistically test the significance of the differences described.RESULTS: Our preliminary data reveals that lifetime of dysplastic or neoplastic samples may be either shorter or longer than that of normal tissue. Increased lifetime values have been observed in Barrett’s oesophagus, colon cancer and polyps. Gastric cancer and ulcerative colitis have shown a decrease in lifetime. In addition, a broadening of
Thompson A, Manning H, Brydegaard M, et al., 2011, Hyperspectral fluorescence lifetime fibre probe spectroscopy for use in the study and diagnosis of osteoarthritis and skin cancer, SPIE Photonics West 2011, Publisher: Society of Photo-optical Instrumentation Engineers (SPIE), ISSN: 1996-756X
We present the application of two fibre-optic-coupled time-resolved spectrofluorometers and a compact steady-state diffuse reflected light/fluorescence spectrometer to in vivo and ex vivo studies of skin cancer and osteoarthritis. In a clinical study of skin cancer, 27 lesions on 25 patients were investigated in vivo before surgical excision of the region measured. Preliminary analysis reveals a statistically significant decrease in the autofluorescence lifetime of basal cell carcinomas compared to neighbouring healthy tissue. A study of autofluorescence signals associated with the onset of osteoarthritis indicates autofluorescence lifetime changes associated with collagen degradation.
Kennedy GT, Coda S, Thompson AJ, et al., 2011, Fluorescence Lifetime Imaging Endoscopy, Conference on Endoscopic Microscopy VI, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
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- Citations: 3
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