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Summers PA, Thomas AP, Kench T, Vannier JB, Kuimova MK, Vilar R. Cationic helicenes as selective G4 DNA binders and optical probes for cellular imaging. Chem Sci 2021; 12:14624-14634. [PMID: 34881015 PMCID: PMC8580066 DOI: 10.1039/d1sc04567a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 10/12/2021] [Indexed: 01/17/2023] Open
Abstract
The important role that G-quadruplex DNA (G4 DNA) structures play in regulating biological processes is becoming widely recognised. These structures have also been proposed to be attractive drug targets. Therefore, there has been significant interest in developing small molecules that can selectively bind to G4 DNA over other topologies. In this paper we investigate the interaction between DNA and helical compounds (helicenes) based on a central carbocation trisubstituted with aromatic rings. We show that the non-planar structure of these helicenes results in a significantly reduced affinity for dsDNA when compared to their planar analogues, whilst maintaining a high affinity for G4 DNA. Additionally, the right- and left-handed enantiomers of one of these helicenes recognise the chiral DNA environments of G4 and dsDNA differently. We show that upon DNA binding the helicenes display a fluorescence switch-on effect, which we have successfully used for cellular imaging in live and fixed U2OS cells, staining mitochondria and the nucleus, respectively.
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Affiliation(s)
- Peter A Summers
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London 82 Wood Lane, White City Campus W12 0BZ UK +44 (0)20 7594 1967 +44 (0)20 7594 8558
| | - Ajesh P Thomas
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London 82 Wood Lane, White City Campus W12 0BZ UK +44 (0)20 7594 1967 +44 (0)20 7594 8558
| | - Timothy Kench
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London 82 Wood Lane, White City Campus W12 0BZ UK +44 (0)20 7594 1967 +44 (0)20 7594 8558
| | - Jean-Baptiste Vannier
- Telomere Replication and Stability Group, Medical Research Council - London Institute of Medical Sciences London W12 0NN UK
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London London W12 0NN UK
| | - Marina K Kuimova
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London 82 Wood Lane, White City Campus W12 0BZ UK +44 (0)20 7594 1967 +44 (0)20 7594 8558
| | - Ramon Vilar
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London 82 Wood Lane, White City Campus W12 0BZ UK +44 (0)20 7594 1967 +44 (0)20 7594 8558
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2
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Priessner M, Summers PA, Lewis BW, Sastre M, Ying L, Kuimova MK, Vilar R. Selective Detection of Cu
+
Ions in Live Cells via Fluorescence Lifetime Imaging Microscopy. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Martin Priessner
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - Peter A. Summers
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - Benjamin W. Lewis
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - Magdalena Sastre
- Department of Brain Sciences Imperial College London Hammersmith Campus London W12 0NN UK
| | - Liming Ying
- National Heart and Lung Institute Molecular Sciences Research Hub White City Campus Imperial College London London W12 0BZ UK
| | - Marina K. Kuimova
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - Ramon Vilar
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
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3
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Priessner M, Summers PA, Lewis BW, Sastre M, Ying L, Kuimova MK, Vilar R. Selective Detection of Cu + Ions in Live Cells via Fluorescence Lifetime Imaging Microscopy. Angew Chem Int Ed Engl 2021; 60:23148-23153. [PMID: 34379368 PMCID: PMC8596571 DOI: 10.1002/anie.202109349] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Indexed: 11/06/2022]
Abstract
Copper is an essential trace element in living organisms with its levels and localisation being carefully managed by the cellular machinery. However, if misregulated, deficiency or excess of copper ions can lead to several diseases. Therefore, it is important to have reliable methods to detect, monitor and visualise this metal in cells. Herein we report a new optical probe based on BODIPY, which shows a switch-on in its fluorescence intensity upon binding to copper(I), but not in the presence of high concentration of other physiologically relevant metal ions. More interestingly, binding to copper(I) leads to significant changes in the fluorescence lifetime of the new probe, which can be used to visualize copper(I) pools in lysosomes of live cells via fluorescence lifetime imaging microscopy (FLIM).
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Affiliation(s)
- Martin Priessner
- Department of ChemistryImperial College LondonWhite City CampusLondonW12 0BZUK
| | - Peter A. Summers
- Department of ChemistryImperial College LondonWhite City CampusLondonW12 0BZUK
| | - Benjamin W. Lewis
- Department of ChemistryImperial College LondonWhite City CampusLondonW12 0BZUK
| | - Magdalena Sastre
- Department of Brain SciencesImperial College LondonHammersmith CampusLondonW12 0NNUK
| | - Liming Ying
- National Heart and Lung InstituteMolecular Sciences Research HubWhite City CampusImperial College LondonLondonW12 0BZUK
| | - Marina K. Kuimova
- Department of ChemistryImperial College LondonWhite City CampusLondonW12 0BZUK
| | - Ramon Vilar
- Department of ChemistryImperial College LondonWhite City CampusLondonW12 0BZUK
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4
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Kench T, Summers PA, Kuimova MK, Lewis JEM, Vilar R. Rotaxanes as Cages to Control DNA Binding, Cytotoxicity, and Cellular Uptake of a Small Molecule*. Angew Chem Int Ed Engl 2021; 60:10928-10934. [PMID: 33577711 DOI: 10.1002/anie.202100151] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/08/2021] [Indexed: 11/08/2022]
Abstract
The efficacy of many drugs can be limited by undesirable properties, such as poor aqueous solubility, low bioavailability, and "off-target" interactions. To combat this, various drug carriers have been investigated to enhance the pharmacological profile of therapeutic agents. In this work, we demonstrate the use of mechanical protection to "cage" a DNA-targeting metallodrug within a photodegradable rotaxane. More specifically, we report the synthesis of rotaxanes incorporating as a stoppering unit a known G-quadruplex DNA binder, namely a PtII -salphen complex. This compound cannot interact with DNA when it is part of the mechanically interlocked assembly. The second rotaxane stopper can be cleaved by either light or an esterase, releasing the PtII -salphen complex. This system shows enhanced cell permeability and limited cytotoxicity within osteosarcoma cells compared to the free drug. Light activation leads to a dramatic increase in cytotoxicity, arising from the translocation of PtII -salphen to the nucleus and its binding to DNA.
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Affiliation(s)
- Timothy Kench
- Department of Chemistry, Imperial College London, White City Campus, London, W12 0BZ, UK
| | - Peter A Summers
- Department of Chemistry, Imperial College London, White City Campus, London, W12 0BZ, UK
| | - Marina K Kuimova
- Department of Chemistry, Imperial College London, White City Campus, London, W12 0BZ, UK
| | - James E M Lewis
- Department of Chemistry, Imperial College London, White City Campus, London, W12 0BZ, UK
| | - Ramon Vilar
- Department of Chemistry, Imperial College London, White City Campus, London, W12 0BZ, UK
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5
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Kench T, Summers PA, Kuimova MK, Lewis JEM, Vilar R. Rotaxanes as Cages to Control DNA Binding, Cytotoxicity, and Cellular Uptake of a Small Molecule**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202100151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Timothy Kench
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - Peter A. Summers
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - Marina K. Kuimova
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - James E. M. Lewis
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
| | - Ramon Vilar
- Department of Chemistry Imperial College London White City Campus London W12 0BZ UK
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6
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Lewis BW, Bisballe N, Santella M, Summers PA, Vannier JB, Kuimova MK, Laursen BW, Vilar R. Assessing The Key Photophysical Properties of Triangulenium Dyes for DNA Binding by Alteration of the Fluorescent Core. Chemistry 2021; 27:2523-2536. [PMID: 33105523 DOI: 10.1002/chem.202003875] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Indexed: 11/09/2022]
Abstract
Four-stranded G-quadruplex (G4) DNA is a non-canonical DNA topology that has been proposed to form in cells and play key roles in how the genome is read and used by the cellular machinery. Previously, a fluorescent triangulenium probe (DAOTA-M2) was used to visualise G4s in cellulo, thanks to its distinct fluorescence lifetimes when bound to different DNA topologies. Herein, the library of available triangulenium probes is expanded to explore how modifications to the fluorescent core of the molecule affect its photophysical characteristics, interaction with DNA and cellular localisation. The benzo-bridged and isopropyl-bridged diazatriangulenium dyes, BDATA-M2 and CDATA-M2 respectively, featuring ethyl-morpholino substituents, were synthesised and characterised. The interactions of these molecules with different DNA topologies were studied to determine their binding affinity, fluorescence enhancement and fluorescence lifetime response. Finally, the cellular uptake and localisation of these optical probes were investigated. Whilst structural modifications to the triangulenium core only slightly alter the binding affinity to DNA, BDATA-M2 and CDATA-M2 cannot distinguish between DNA topologies through their fluorescence lifetime. It is argued theoretically and experimentally that this is due to reduced effectiveness of photoinduced electron transfer (PET) quenching. This work presents valuable new evidence into the critical role of PET quenching when using the fluorescence lifetime of triangulenium dyes to discriminate G4 DNA from duplex DNA, highlighting the importance of fine tuning redox and spectral properties when developing new triangulenium-based G4 probes.
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Affiliation(s)
- Benjamin W Lewis
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK.,Institute of Chemical Biology, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Niels Bisballe
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Marco Santella
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Peter A Summers
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Jean-Baptiste Vannier
- Telomere Replication and Stability Group, Medical Research Council-London Institute of Medical Sciences, London, W12 0NN, UK.,Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Marina K Kuimova
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK.,Institute of Chemical Biology, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Bo W Laursen
- Department of Chemistry & Nano-Science Center, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Ramon Vilar
- Department of Chemistry, Molecular Sciences Research Hub, White City Campus, Imperial College London, London, W12 0BZ, UK.,Institute of Chemical Biology, White City Campus, Imperial College London, London, W12 0BZ, UK
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7
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Reeh K, Summers PA, Gould IR, Woscholski R, Vilar R. Design, synthesis and evaluation of a tripodal receptor for phosphatidylinositol phosphates. Sci Rep 2020; 10:18450. [PMID: 33116198 PMCID: PMC7595110 DOI: 10.1038/s41598-020-75484-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 10/15/2020] [Indexed: 11/30/2022] Open
Abstract
Phosphatidylinositol phosphates (PIPs) are membrane phospholipids that play crucial roles in a wide range of cellular processes. Their function is dictated by the number and positions of the phosphate groups in the inositol ring (with seven different PIPs being active in the cell). Therefore, there is significant interest in developing small-molecule receptors that can bind selectively to these species and in doing so affect their cellular function or be the basis for molecular probes. However, to date there are very few examples of such molecular receptors. Towards this aim, herein we report a novel tripodal molecule that acts as receptor for mono- and bis-phosphorylated PIPs in a cell free environment. To assess their affinity to PIPs we have developed a new cell free assay based on the ability of the receptor to prevent alkaline phosphatase from hydrolysing these substrates. The new receptor displays selectivity towards two out of the seven PIPs, namely PI(3)P and PI(3,4)P2. To rationalise these results, a DFT computational study was performed which corroborated the experimental results and provided insight into the host-guest binding mode.
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Affiliation(s)
- Katharina Reeh
- Department of Chemistry, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK
- Institute of Chemical Biology, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK
| | - Peter A Summers
- Department of Chemistry, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK
| | - Ian R Gould
- Department of Chemistry, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK
- Institute of Chemical Biology, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK
| | - Rudiger Woscholski
- Department of Chemistry, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK
- Institute of Chemical Biology, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK
| | - Ramon Vilar
- Department of Chemistry, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK.
- Institute of Chemical Biology, Imperial College London, White City Campus, 84 Wood Lane, London, W12 0BZ, UK.
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8
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Shi Y, Summers PA, Kuimova MK, Azevedo HS. Unravelling the Enzymatic Degradation Mechanism of Supramolecular Peptide Nanofibers and Its Correlation with Their Internal Viscosity. Nano Lett 2020; 20:7375-7381. [PMID: 32866016 DOI: 10.1021/acs.nanolett.0c02781] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Enzyme-responsive supramolecular peptide biomaterials have attracted growing interest for disease diagnostics and treatments. However, it remains unclear whether enzymes target the peptide assemblies or dissociated peptide monomers. To gain further insight into the degradation mechanism of supramolecular peptide amphiphile (PA) nanofibers, cathepsin B with both exopeptidase and endopeptidase activities was exploited here for degradation studies. Hydrolysis was found to occur directly on the PA nanofibers as only surface amino acid residues were cleaved. The number of cleaved residues and the degradation efficiency was observed to be negatively correlated with the internal viscosity of the PA nanofibers, quantified to be between 200-800 cP (liquid phase) using fluorescence lifetime imaging microscopy combined with an environmentally sensitive molecular rotor, BODIPY-C10. These findings enhance our understanding on the enzymatic degradation of supramolecular PA nanofibers and have important implications for the development of PA probes for the real-time monitoring of disease-related enzymes.
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Affiliation(s)
- Yejiao Shi
- School of Engineering and Materials Science and Institute of Bioengineering, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Peter A Summers
- Department of Chemistry and Molecular Science Research Hub, Imperial College London, White City Campus, London W12 0BZ, United Kingdom
| | - Marina K Kuimova
- Department of Chemistry and Molecular Science Research Hub, Imperial College London, White City Campus, London W12 0BZ, United Kingdom
| | - Helena S Azevedo
- School of Engineering and Materials Science and Institute of Bioengineering, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
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9
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Maurice J, Lett AM, Skinner C, Lim A, Richardson M, Thomas AP, Summers PA, Vyas K, Tadbier AW, Vilar R, Kuimova MK, Miodragovic S, Vergis N, Kelly P, Cordeiro MF, Hoare J, Darzi A, Goldin R, Thursz M, Thompson AJ. Transcutaneous fluorescence spectroscopy as a tool for non-invasive monitoring of gut function: first clinical experiences. Sci Rep 2020; 10:16169. [PMID: 32999336 PMCID: PMC7527451 DOI: 10.1038/s41598-020-73149-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 09/10/2020] [Indexed: 01/27/2023] Open
Abstract
Gastro-intestinal function plays a vital role in conditions ranging from inflammatory bowel disease and HIV through to sepsis and malnutrition. However, the techniques that are currently used to assess gut function are either highly invasive or unreliable. Here we present an alternative, non-invasive sensing modality for assessment of gut function based on fluorescence spectroscopy. In this approach, patients receive an oral dose of a fluorescent contrast agent and a fibre-optic probe is used to make fluorescence measurements through the skin. This provides a readout of the degree to which fluorescent dyes have permeated from the gut into the blood stream. We present preliminary results from our first measurements in human volunteers demonstrating the potential of the technique for non-invasive monitoring of multiple aspects of gastro-intestinal health.
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Affiliation(s)
- James Maurice
- Department of Surgery & Cancer, St. Mary's Hospital Campus, Imperial College London, London, W2 1NY, UK
| | - Aaron M Lett
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, W2 1NY, UK
| | - Charlotte Skinner
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, W2 1NY, UK
| | - Alexandra Lim
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, W2 1NY, UK
| | - Matthew Richardson
- Imperial College Ophthalmology Research Group, Western Eye Hospital, Imperial College London, London, NW1 5QH, UK
| | - Ajesh Painadath Thomas
- Department of Chemistry, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Peter A Summers
- Department of Chemistry, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Khushi Vyas
- The Hamlyn Centre, Institute of Global Health Innovation, South Kensington, Imperial College London, London, SW7 2AZ, UK
| | - Abdul Wadood Tadbier
- Department of Surgery & Cancer, St. Mary's Hospital Campus, Imperial College London, London, W2 1NY, UK.,The Hamlyn Centre, Institute of Global Health Innovation, South Kensington, Imperial College London, London, SW7 2AZ, UK
| | - Ramon Vilar
- Department of Chemistry, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Marina K Kuimova
- Department of Chemistry, White City Campus, Imperial College London, London, W12 0BZ, UK
| | - Serge Miodragovic
- Imperial College Ophthalmology Research Group, Western Eye Hospital, Imperial College London, London, NW1 5QH, UK
| | - Nikhil Vergis
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, W2 1NY, UK
| | - Paul Kelly
- Blizard Institute, Queen Mary University of London, London, E1 2AT, UK.,Tropical Gastroenterology and Nutrition Group, University of Zambia School of Medicine, Lusaka, Zambia
| | - Maria Francesca Cordeiro
- Imperial College Ophthalmology Research Group, Western Eye Hospital, Imperial College London, London, NW1 5QH, UK
| | - Jonathan Hoare
- Department of Surgery & Cancer, St. Mary's Hospital Campus, Imperial College London, London, W2 1NY, UK
| | - Ara Darzi
- Department of Surgery & Cancer, St. Mary's Hospital Campus, Imperial College London, London, W2 1NY, UK.,The Hamlyn Centre, Institute of Global Health Innovation, South Kensington, Imperial College London, London, SW7 2AZ, UK
| | - Robert Goldin
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, W2 1NY, UK
| | - Mark Thursz
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, W2 1NY, UK
| | - Alex J Thompson
- Department of Surgery & Cancer, St. Mary's Hospital Campus, Imperial College London, London, W2 1NY, UK. .,The Hamlyn Centre, Institute of Global Health Innovation, South Kensington, Imperial College London, London, SW7 2AZ, UK.
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10
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Bednarska J, Pelchen-Matthews A, Novak P, Burden JJ, Summers PA, Kuimova MK, Korchev Y, Marsh M, Shevchuk A. Rapid formation of human immunodeficiency virus-like particles. Proc Natl Acad Sci U S A 2020; 117:21637-21646. [PMID: 32817566 PMCID: PMC7474690 DOI: 10.1073/pnas.2008156117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Understanding the molecular mechanisms involved in the assembly of viruses is essential for discerning how viruses transmit from cell to cell and host to host. Although molecular aspects of assembly have been studied for many viruses, we still have little information about these events in real time. Enveloped viruses such as HIV that assemble at, and bud from, the plasma membrane have been studied in some detail using live cell fluorescence imaging techniques; however, these approaches provide little information about the real-time morphological changes that take place as viral components come together to form individual virus particles. Here we used correlative scanning ion conductance microscopy and fluorescence confocal microscopy to measure the topological changes, together with the recruitment of fluorescently labeled viral proteins such as Gag and Vpr, during the assembly and release of individual HIV virus-like particles (VLPs) from the top, nonadherent surfaces of living cells. We show that 1) labeling of viral proteins with green fluorescent protein affects particle formation, 2) the kinetics of particle assembly on different plasma membrane domains can vary, possibly as a consequence of differences in membrane biophysical properties, and 3) VLPs budding from the top, unimpeded surface of cells can reach full size in 20 s and disappear from the budding site in 0.5 to 3 min from the moment curvature is initially detected, significantly faster than has been previously reported.
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Affiliation(s)
- Joanna Bednarska
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom
| | - Annegret Pelchen-Matthews
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E 6BT London, United Kingdom
| | - Pavel Novak
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom
- Functional Low-Dimensional Structures Laboratory, National University of Science and Technology "MISIS", 119991 Moscow, Russian Federation
| | - Jemima J Burden
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E 6BT London, United Kingdom
| | - Peter A Summers
- Molecular Sciences Research Hub, Department of Chemistry, Imperial College London, W12 0BZ London, United Kingdom
| | - Marina K Kuimova
- Molecular Sciences Research Hub, Department of Chemistry, Imperial College London, W12 0BZ London, United Kingdom
| | - Yuri Korchev
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom
- Nano Life Science Institute, Kanazawa University, 920-1192 Kanazawa, Japan
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E 6BT London, United Kingdom;
| | - Andrew Shevchuk
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom;
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11
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Kubánková M, Summers PA, López-Duarte I, Kiryushko D, Kuimova MK. Microscopic Viscosity of Neuronal Plasma Membranes Measured Using Fluorescent Molecular Rotors: Effects of Oxidative Stress and Neuroprotection. ACS Appl Mater Interfaces 2019; 11:36307-36315. [PMID: 31513373 DOI: 10.1021/acsami.9b10426] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Molecular mobility in neuronal plasma membranes is a crucial factor in brain function. Microscopic viscosity is an important parameter that determines molecular mobility. This study presents the first direct measurement of the microviscosity of plasma membranes of live neurons. Microviscosity maps were obtained using fluorescence lifetime imaging of environment-sensing dyes termed "molecular rotors". Neurons were investigated both in the basal state and following common neurodegenerative stimuli, excitotoxicity, or oxidative stress. Both types of neurotoxic challenges induced microviscosity decrease in cultured neurons, and oxidant-induced membrane fluidification was counteracted by the wide-spectrum neuroprotectant, the H3 peptide. These results provide new insights into molecular mobility in neuronal membranes, paramount for basic brain function, and suggest that preservation of membrane stability may be an important aspect of neuroprotection in brain insults and neurodegenerative disorders.
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Affiliation(s)
| | | | | | - Darya Kiryushko
- Centre for Neuroinflammation and Neurodegeneration , Imperial College London , Hammersmith Hospital Campus, Burlington Danes Building, 160 Du Cane Road , London W12 0NN , U.K
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12
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Gu F, Guo J, Zhang W, Summers PA, Hall P. From waste plastics to industrial raw materials: A life cycle assessment of mechanical plastic recycling practice based on a real-world case study. Sci Total Environ 2017; 601-602:1192-1207. [PMID: 28605837 DOI: 10.1016/j.scitotenv.2017.05.278] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 05/29/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
Mechanical recycling of waste plastics is an environmental solution to the problem of waste plastic disposal, and has already become a common practice in industry. However, limited information can be found on either the industralised plastic recycling or the recycled materials, despite the use of recycled plastics has already extended to automobile production. This study investigates the life cycle environmental impacts of mechanical plastic recycling practice of a plastic recycling company in China. Waste plastics from various sources, such as agricultural wastes, plastic product manufacturers, collected solid plastic wastes and parts dismantled from waste electric and electronic equipments, are processed in three routes with products end up in different markets. The results of life cycle assessments show that the extrusion process has the largest environmental impacts, followed by the use of fillers and additives. Compared to production of virgin plastics and composites, the mechanical recycling is proved to be a superior alternative in most environmental aspects. Substituting virgin plastic composites with recycled plastic composites has achieved the highest environmental benefits, as virgin composite production has an impact almost 4 times higher that of the recycled composite production in each ReCiPe endpoint damage factor. Sensitivity analysis shows that the coverage of collecting network contribute affect little to overall environmental impact, and centralisation plays an important role in reducing overall environmental impacts. Among the fillers and additives, impact modifiers account for the most significant contributions to the environmental impacts of recycled composites. This study provides necessary information about the existing industrialised plastic recycling practice, and recommendations are given. Research implications are presented with the purpose to achieve higher substitution rate and lower environmental impact.
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Affiliation(s)
- Fu Gu
- Department of Chemical and Environmental Engineering, Nottingham University, Ningbo 315100, China
| | - Jianfeng Guo
- Center of Energy and Environmental Policy Research, Institute of Policy and Management, Chinese Academy of Sciences, Beijing 100190, China.
| | - Wujie Zhang
- Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province, College of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China
| | - Peter A Summers
- Department of Chemical and Environmental Engineering, Nottingham University, Ningbo 315100, China
| | - Philip Hall
- Department of Chemical and Environmental Engineering, Nottingham University, Ningbo 315100, China
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Gu F, Ma B, Guo J, Summers PA, Hall P. Internet of things and Big Data as potential solutions to the problems in waste electrical and electronic equipment management: An exploratory study. Waste Manag 2017; 68:434-448. [PMID: 28757222 DOI: 10.1016/j.wasman.2017.07.037] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 06/29/2017] [Accepted: 07/21/2017] [Indexed: 06/07/2023]
Abstract
Management of Waste Electrical and Electronic Equipment (WEEE) is a vital part in solid waste management, there are still some difficult issues require attentionss. This paper investigates the potential of applying Internet of Things (IoT) and Big Data as the solutions to the WEEE management problems. The massive data generated during the production, consumption and disposal of Electrical and Electronic Equipment (EEE) fits the characteristics of Big Data. Through using the state-of-the-art communication technologies, the IoT derives the WEEE "Big Data" from the life cycle of EEE, and the Big Data technologies process the WEEE "Big Data" for supporting decision making in WEEE management. The framework of implementing the IoT and the Big Data technologies is proposed, with its multiple layers are illustrated. Case studies with the potential application scenarios of the framework are presented and discussed. As an unprecedented exploration, the combined application of the IoT and the Big Data technologies in WEEE management brings a series of opportunities as well as new challenges. This study provides insights and visions for stakeholders in solving the WEEE management problems under the context of IoT and Big Data.
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Affiliation(s)
- Fu Gu
- Department of Chemical and Environmental Engineering, Nottingham University, Ningbo 315100, China
| | - Buqing Ma
- Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province, College of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jianfeng Guo
- Center of Energy and Environmental Policy Research, Institute of Policy and Management, Chinese Academy of Sciences, Beijing 100190, China.
| | - Peter A Summers
- Department of Chemical and Environmental Engineering, Nottingham University, Ningbo 315100, China
| | - Philip Hall
- Department of Chemical and Environmental Engineering, Nottingham University, Ningbo 315100, China
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14
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Summers PA, Calladine JA, Ghiotto F, Dawson J, Sun XZ, Hamilton ML, Towrie M, Davies ES, McMaster J, George MW, Schröder M. Synthesis and Photophysical Study of a [NiFe] Hydrogenase Biomimetic Compound Covalently Linked to a Re-diimine Photosensitizer. Inorg Chem 2015; 55:527-36. [PMID: 26605700 PMCID: PMC4774970 DOI: 10.1021/acs.inorgchem.5b01744] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The synthesis, photophysics, and
photochemistry of a linked dyad ([Re]-[NiFe2]) containing
an analogue ([NiFe2]) of the active site of [NiFe] hydrogenase,
covalently bound to a Re-diimine photosensitizer ([Re]), are described.
Following excitation, the mechanisms of electron transfer involving
the [Re] and [NiFe2] centers and the resulting decomposition
were investigated. Excitation of the [Re] center results in the population
of a diimine-based metal-to-ligand charge transfer excited state.
Reductive quenching by NEt3 produces the radically reduced
form of [Re], [Re]− (kq = 1.4 ± 0.1 × 107 M–1 s–1). Once formed, [Re]− reduces the
[NiFe2] center to [NiFe2]−, and this reduction was followed using time-resolved infrared spectroscopy.
The concentration dependence of the electron transfer rate constants
suggests that both inter- and intramolecular electron transfer pathways
are involved, and the rate constants for these processes have been
estimated (kinter = 5.9 ± 0.7 ×
108 M–1 s–1, kintra = 1.5 ± 0.1 × 105 s–1). For the analogous bimolecular system, only
intermolecular electron transfer could be observed (kinter = 3.8 ± 0.5 × 109 M–1 s–1). Fourier transform infrared spectroscopic
studies confirms that decomposition of the dyad occurs upon prolonged
photolysis, and this appears to be a major factor for the low activity
of the system toward H2 production in acidic conditions. Excitation of the [Re] center in the linked-dyad complex
([Re]-[NiFe2]) populates the 3MLCT excited state,
and reductive quenching by NEt3 produces [Re]−. [Re]− reduces the [NiFe2] center to
[NiFe2]− via inter- and intramolecular
electron transfer pathways (kinter = 5.9
± 0.7 × 108 M−1 s−1, kintra = 1.5 ± 0.1 × 105 s−1). For the analogous bimolecular system,
where only intermolecular electron transfer could be observed, kinter = 3.8 ± 0.5 × 109 M−1 s−1.
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Affiliation(s)
- Peter A Summers
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.,Department of Chemical and Environmental Engineering, The University of Nottingham Ningbo China , Ningbo 315100, China
| | - James A Calladine
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom
| | - Fabio Ghiotto
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom
| | - Joe Dawson
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom
| | - Xue-Z Sun
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom
| | - Michelle L Hamilton
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.,Dynamic Structural Science Consortium, Research Complex at Harwell , Didcot, Oxfordshire OX11 0FA, United Kingdom
| | - Michael Towrie
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Rutherford Appleton Laboratory , Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - E Stephen Davies
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom
| | - Jonathan McMaster
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom
| | - Michael W George
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.,Department of Chemical and Environmental Engineering, The University of Nottingham Ningbo China , Ningbo 315100, China
| | - Martin Schröder
- School of Chemistry, The University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.,School of Chemistry, University of Manchester , Manchester M13 9PL, United Kingdom
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15
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Windle CD, George MW, Perutz RN, Summers PA, Sun XZ, Whitwood AC. Comparison of rhenium-porphyrin dyads for CO 2 photoreduction: photocatalytic studies and charge separation dynamics studied by time-resolved IR spectroscopy. Chem Sci 2015; 6:6847-6864. [PMID: 29861927 PMCID: PMC5947513 DOI: 10.1039/c5sc02099a] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 08/18/2015] [Indexed: 01/08/2023] Open
Abstract
We report a study of the photocatalytic reduction of CO2 to CO by zinc porphyrins covalently linked to [ReI(2,2'-bipyridine)(CO)3L]+/0 moieties with visible light of wavelength >520 nm. Dyad 1 contains an amide C6H4NHC(O) link from porphyrin to bipyridine (Bpy), Dyad 2 contains an additional methoxybenzamide within the bridge C6H4NHC(O)C6H3(OMe)NHC(O), while Dyad 3 has a saturated bridge C6H4NHC(O)CH2; each dyad is studied with either L = Br or 3-picoline. The syntheses, spectroscopic characterisation and cyclic voltammetry of Dyad 3 Br and [Dyad 3 pic]OTf are described. The photocatalytic performance of [Dyad 3 pic]OTf in DMF/triethanolamine (5 : 1) is approximately an order of magnitude better than [Dyad 1 pic]PF6 or [Dyad 2 pic]OTf in turnover frequency and turnover number, reaching a turnover number of 360. The performance of the dyads with Re-Br units is very similar to that of the dyads with [Re-pic]+ units in spite of the adverse free energy of electron transfer. The dyads undergo reactions during photocatalysis: hydrogenation of the porphyrin to form chlorin and isobacteriochlorin units is detected by visible absorption spectroscopy, while IR spectroscopy reveals replacement of the axial ligand by a triethanolaminato group and insertion of CO2 into the latter to form a carbonate. Time-resolved IR spectra of [Dyad 2 pic]OTf and [Dyad 3 pic]OTf (560 nm excitation in CH2Cl2) demonstrated electron transfer from porphyrin to Re(Bpy) units resulting in a shift of ν(CO) bands to low wavenumbers. The rise time of the charge-separated species for [Dyad 3 pic]OTf is longest at 8 (±1) ps and its lifetime is also the longest at 320 (±15) ps. The TRIR spectra of Dyad 1 Br and Dyad 2 Br are quite different showing a mixture of 3MLCT, IL and charge-separated excited states. In the case of Dyad 3 Br, the charge-separated state is absent altogether. The TRIR spectra emphasize the very different excited states of the bromide complexes and the picoline complexes. Thus, the similarity of the photocatalytic data for bromide and picoline dyads suggests that they share common intermediates. Most likely, these involve hydrogenation of the porphyrin and substitution of the axial ligand at rhenium.
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Affiliation(s)
- Christopher D Windle
- Department of Chemistry , University of York , Heslington , York , YO10 5DD , UK .
| | - Michael W George
- School of Chemistry , University of Nottingham , Nottingham , NG7 2RD , UK . .,Department of Chemical and Environmental Engineering , The University of Nottingham Ningbo China , Ningbo , 315100 , China
| | - Robin N Perutz
- Department of Chemistry , University of York , Heslington , York , YO10 5DD , UK .
| | - Peter A Summers
- School of Chemistry , University of Nottingham , Nottingham , NG7 2RD , UK . .,Department of Chemical and Environmental Engineering , The University of Nottingham Ningbo China , Ningbo , 315100 , China
| | - Xue Zhong Sun
- School of Chemistry , University of Nottingham , Nottingham , NG7 2RD , UK .
| | - Adrian C Whitwood
- Department of Chemistry , University of York , Heslington , York , YO10 5DD , UK .
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Moyers MF, Ibbott GS, Grant RL, Summers PA, Followill DS. Independent dose per monitor unit review of eight U.S.A. proton treatment facilities. Med Phys 2014; 41:012103. [PMID: 24387521 DOI: 10.1118/1.4845135] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Compare the dose per monitor unit at different proton treatment facilities using three different dosimetry methods. METHODS Measurements of dose per monitor unit were performed by a single group at eight facilities using 11 test beams and up to six different clinical portal treatment sites. These measurements were compared to the facility reported dose per monitor unit values. RESULTS Agreement between the measured and reported doses was similar using any of the three dosimetry methods. Use of the ICRU 59 ND,w based method gave results approximately 3% higher than both the ICRU 59 NX and ICRU 78 (TRS-398) ND,w based methods. CONCLUSIONS Any single dosimetry method could be used for multi-institution trials with similar conformity between facilities. A multi-institutional trial could support facilities using both the ICRU 59 NX based and ICRU 78 (TRS-398) ND,w based methods but use of the ICRU 59 ND,w based method should not be allowed simultaneously with the other two until the difference is resolved.
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Affiliation(s)
| | - G S Ibbott
- Department of Radiation Physics, University of Texas - M. D. Anderson Cancer Center, Houston, Texas 77030
| | - R L Grant
- Department of Radiation Physics, University of Texas - M. D. Anderson Cancer Center, Houston, Texas 77030
| | - P A Summers
- Department of Radiation Physics, University of Texas - M. D. Anderson Cancer Center, Houston, Texas 77030
| | - D S Followill
- Department of Radiation Physics, University of Texas - M. D. Anderson Cancer Center, Houston, Texas 77030
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Summers PA, Dawson J, Ghiotto F, Hanson-Heine MWD, Vuong KQ, Stephen Davies E, Sun XZ, Besley NA, McMaster J, George MW, Schröder M. Photochemical Dihydrogen Production Using an Analogue of the Active Site of [NiFe] Hydrogenase. Inorg Chem 2014; 53:4430-9. [DOI: 10.1021/ic500089b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Peter A. Summers
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Joe Dawson
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Fabio Ghiotto
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | | | - Khuong Q. Vuong
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - E. Stephen Davies
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Xue-Z. Sun
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Nicholas A. Besley
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Jonathan McMaster
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Michael W. George
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Martin Schröder
- School of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
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Iqbal K, Gillin M, Summers PA, Dhanesar S, Gifford KA, Buzdar SA. Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom. Br J Radiol 2013; 86:20130390. [PMID: 24049129 DOI: 10.1259/bjr.20130390] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The purpose of this study was to evaluate spot scanning proton therapy with an anthropomorphic prostate phantom at the Proton Therapy Center of The University of Texas MD Anderson Cancer Center at Houston, TX (PTCH). METHODS An anthropomorphic prostate phantom from the Radiological Physics Center (RPC), The University of Texas MD Anderson Cancer Center, Houston, TX, was used, which contained thermoluminescent dosemeters and GAFCHROMIC(®) EBT2 film (ISP Technologies, Wayne, NJ). The phantom was irradiated by the Hitachi synchrotron (Hitachi America, Ltd, Tarrytown, NY), and the results were compared between the treatment planning system (TPS) and RPC measurements. RESULTS RPC results show that the right/left, inferior/superior and posterior/anterior aspects of the coronal/sagittal and EBT2 film measurements were within ±7%/±4 mm of the TPS. The RPC thermoluminescent dosemeter measurements of the prostate and femoral heads were within 3% of the TPS. CONCLUSION The RPC prostate phantom is a useful mechanism to evaluate spot scanning beam proton therapy within certain confidence levels. ADVANCES IN KNOWLEDGE The RPC anthropomorphic prostate phantom could be used to establish quality assurance of spot scanning proton beam for patients with prostate cancer.
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Affiliation(s)
- K Iqbal
- Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Lass NJ, Hinzman AR, Eastham SK, Wright TL, Mills KJ, Bartlett BS, Summers PA. Listeners' discrimination of real and human-imitated animal sounds. Percept Mot Skills 1984; 58:453-4. [PMID: 6739242 DOI: 10.2466/pms.1984.58.2.453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
To determine if listeners can accurately distinguish between real and human-imitated animal sounds, a total of 165 recorded sounds (55 real and 110 human-imitated) of cats, cows, dogs, pigs, and sheep were randomly arranged on a master tape and presented to 30 listeners for discriminative judgments. Results indicate that, in general, listeners can accurately discriminate real from human-imitated animal sounds. Suggestions for future research are discussed.
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Larson GW, Summers PA. Comparison of sampling techniques in the measurement of children's morphological development. J Commun Disord 1982; 15:251-257. [PMID: 7096622 DOI: 10.1016/0021-9924(82)90038-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Sixty children ranging in age from 66 to 78 months were administered the Berry-Talbott Exploratory Test of Grammar and the Grammatic Closure subtest of the Illinois Test of Psycholinguistic Development. The verbal responses obtained of each child from each sampling technique were compared on matched grammatical items. A correlation coefficient between the two test group means indicated only moderate correlation. An analysis of the matched grammatical items (40 comparisons) showed a higher correct response frequency for the Grammatic Closure items than for the Berry-Talbott items. However, children who did achieve correct responses to the Berry-Talbott items almost always achieved success with the Grammatic Closure test items. Success on the Grammatic Closure items did not assume success with the Berry-Talbott items. Various hypotheses are offered to explain differences in response patterns.
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Ashburn AD, Weaver MM, Summers PA. Effects of red blood cell injections in diet-induced atrial thrombosis in swiss mice. Am J Anat 1972; 133:341-7. [PMID: 5026659 DOI: 10.1002/aja.1001330308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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