1
|
Woods B, Thompson KC, Szita N, Chen S, Milanesi L, Tomas S. Confinement effect on hydrolysis in small lipid vesicles. Chem Sci 2023; 14:2616-2623. [PMID: 36908967 PMCID: PMC9993861 DOI: 10.1039/d2sc05747f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 02/05/2023] [Indexed: 02/17/2023] Open
Abstract
In living organisms most chemical reactions take place within the confines of lipid-membrane bound compartments, while confinement within the bounds of a lipid membrane is thought to be a key step in abiogenesis. In previous work we demonstrated that confinement in the aqueous cavity of a lipid vesicle affords protection against hydrolysis, a phenomenon that we term here confinement effect (C e) and that we attributed to the interaction with the lipid membrane. Here, we show that both the size and the shape of the cavity of the vesicle modulate the C e. We link this observation to the packing of the lipid following changes in membrane curvature, and formulate a mathematical model that relates the C e to the radius of a spherical vesicle and the packing parameter of the lipids. These results suggest that the shape of the compartment where a molecule is located plays a major role in controlling the chemical reactivity of non-enzymatic reactions. Moreover, the mathematical treatment we propose offers a useful tool for the design of vesicles with predictable reaction rates of the confined molecules, e.g., drug delivery vesicles with confined prodrugs. The results also show that a crude form of signal transduction, devoid of complex biological machinery, can be achieved by any external stimuli that drastically changes the structure of the membrane, like the osmotic shocks used in the present work.
Collapse
Affiliation(s)
- Ben Woods
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK
| | - Katherine C Thompson
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK
| | - Nicolas Szita
- Department of Biochemical Engineering, University College London, Bernard Katz Building Gordon Street London WC1H 0AH UK
| | - Shu Chen
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK
| | - Lilia Milanesi
- Department of Chemistry, University of the Balearic Islands Ctra. de Valldemossa, Km 7.5 07122 Palma de Mallorca Spain
| | - Salvador Tomas
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck, University of London Malet Street London WC1E 7HX UK.,Department of Chemistry, University of the Balearic Islands Ctra. de Valldemossa, Km 7.5 07122 Palma de Mallorca Spain
| |
Collapse
|
2
|
Hemming JM, Szyroka J, Shokano G, Arnold T, Skoda MWA, Rennie AR, Thompson KC. Changes to lung surfactant monolayers upon exposure to gas phase ozone observed using X-ray and neutron reflectivity. Environ Sci : Atmos 2022; 2:753-760. [PMID: 35923664 PMCID: PMC9281625 DOI: 10.1039/d2ea00032f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/30/2022] [Indexed: 11/21/2022]
Abstract
Lung surfactant at the air water interface reacts with ozone leading to changes in surface tension, film thickness, structure.
Collapse
Affiliation(s)
- Joanna M. Hemming
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Justyna Szyroka
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Gracia Shokano
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| | - Thomas Arnold
- European Spallation Source, The ESS Campus, Lund, Sweden, SE-221 00
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
- Department of Chemistry, University of Bath, Claverton Down, Bath, Avon BA2 7AY, UK
| | - Maximilian W. A. Skoda
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell, Didcot, Oxford, OX11 0QX, UK
| | - Adrian R. Rennie
- Department of Chemistry – Ångström and Centre for Neutron Scattering, Uppsala University, Box 538, 75121 Uppsala, Sweden
| | - Katherine C. Thompson
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, Malet Street, London WC1E 7HX, UK
| |
Collapse
|
3
|
Bull GD, Thompson KC. The oxidation of guanine by photoionized 2-aminopurine. Journal of Photochemistry and Photobiology 2021. [DOI: 10.1016/j.jpap.2021.100025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
4
|
King MD, Jones SH, Lucas COM, Thompson KC, Rennie AR, Ward AD, Marks AA, Fisher FN, Pfrang C, Hughes AV, Campbell RA. The reaction of oleic acid monolayers with gas-phase ozone at the air water interface: the effect of sub-phase viscosity, and inert secondary components. Phys Chem Chem Phys 2020; 22:28032-28044. [PMID: 33367378 DOI: 10.1039/d0cp03934a] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Organic films that form on atmospheric particulate matter change the optical and cloud condensation nucleation properties of the particulate matter and consequently have implications for modern climate and climate models. The organic films are subject to attack from gas-phase oxidants present in ambient air. Here we revisit in greater detail the oxidation of a monolayer of oleic acid by gas-phase ozone at the air-water interface as this provides a model system for the oxidation reactions that occur at the air-water interface of aqueous atmospheric aerosol. Experiments were performed on monolayers of oleic acid at the air-liquid interface at atmospherically relevant ozone concentrations to investigate if the viscosity of the sub-phase influences the rate of the reaction and to determine the effect of the presence of a second component within the monolayer, stearic acid, which is generally considered to be non-reactive towards ozone, on the reaction kinetics as determined by neutron reflectometry measurements. Atmospheric aerosol can be extremely viscous. The kinetics of the reaction were found to be independent of the viscosity of the sub-phase below the monolayer over a range of moderate viscosities, , demonstrating no involvement of aqueous sub-phase oxidants in the rate determining step. The kinetics of oxidation of monolayers of pure oleic acid were found to depend on the surface coverage with different behaviour observed above and below a surface coverage of oleic acid of ∼1 × 1018 molecule m-2. Atmospheric aerosol are typically complex mixtures, and the presence of an additional compound in the monolayer that is inert to direct ozone oxidation, stearic acid, did not significantly change the reaction kinetics. It is demonstrated that oleic acid monolayers at the air-water interface do not leave any detectable material at the air-water interface, contradicting the previous work published in this journal which the authors now believe to be erroneous. The combined results presented here indicate that the kinetics, and thus the atmospheric chemical lifetime for unsaturated surface active materials at the air-water interface to loss by reaction with gas-phase ozone, can be considered to be independent of other materials present at either the air-water interface or in the aqueous sub-phase.
Collapse
Affiliation(s)
- Martin D King
- Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, UK.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Abstract
Pyrrolocytosine (PC) and 2-aminopurine (2AP) are fluorescent nucleobase analogues of the DNA nucleobases cytosine and adenine, respectively, and form base pairs with guanine and thymine. Both fluorescent nucleobases are used extensively as probes for local structure in nucleic acids as the fluorescence properties of PC and 2AP are very sensitive to changes such as helix formation, although the reasons for this sensitivity are not clear. To address this question, ab initio calculations have been used to calculate energies, at the MP2 and CIS level, of three different tautomer pairings of PC-G, and two of 2AP-T, which can potentially be interconverted by double proton transfer between the bases. Potential energy curves linking the different tautomer pairs have been calculated. For both PC-G and 2AP-T, the most stable tautomer pair in the electronic ground state is that analogous to the natural C-G and A-T base pair. In the case of 2AP-T, an alternative, stable, tautomer base pair was located in the first electronically excited state; however, it lies higher in energy than the tautomer pair analogous to A-T, making conversion to the alternative form unlikely. In contrast, in the case of PC-G, an alternative tautomer base pair is found to be the most stable form in the first electronically excited state, and this form is accessible following initial excitation from the ground state tautomer pair, thus suggesting an alternative deactivation route via double proton transfer may be possible when PC is involved in hydrogen bonding, such as occurs in helical conformations.
Collapse
Affiliation(s)
- Graham D Bull
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck , University of London , Malet Street , Bloomsbury, London WC1E 7HX , U.K
| | - Katherine C Thompson
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck , University of London , Malet Street , Bloomsbury, London WC1E 7HX , U.K
| |
Collapse
|
6
|
Moulin M, Strohmeier GA, Hirz M, Thompson KC, Rennie AR, Campbell RA, Pichler H, Maric S, Forsyth VT, Haertlein M. Perdeuteration of cholesterol for neutron scattering applications using recombinant Pichia pastoris. Chem Phys Lipids 2018; 212:80-87. [PMID: 29357283 DOI: 10.1016/j.chemphyslip.2018.01.006] [Citation(s) in RCA: 24] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/20/2017] [Accepted: 01/15/2018] [Indexed: 02/08/2023]
Abstract
Deuteration of biomolecules has a major impact on both quality and scope of neutron scattering experiments. Cholesterol is a major component of mammalian cells, where it plays a critical role in membrane permeability, rigidity and dynamics, and contributes to specific membrane structures such as lipid rafts. Cholesterol is the main cargo in low and high-density lipoprotein complexes (i.e. LDL, HDL) and is directly implicated in several pathogenic conditions such as coronary artery disease which leads to 17 million deaths annually. Neutron scattering studies on membranes or lipid-protein complexes exploiting contrast variation have been limited by the lack of availability of fully deuterated biomolecules and especially perdeuterated cholesterol. The availability of perdeuterated cholesterol provides a unique way of probing the structural and dynamical properties of the lipoprotein complexes that underly many of these disease conditions. Here we describe a procedure for in vivo production of perdeuterated recombinant cholesterol in lipid-engineered Pichia pastoris using flask and fed-batch fermenter cultures in deuterated minimal medium. Perdeuteration of the purified cholesterol was verified by mass spectrometry and its use in a neutron scattering study was demonstrated by neutron reflectometry measurements using the FIGARO instrument at the ILL.
Collapse
Affiliation(s)
- Martine Moulin
- Institut Laue-Langevin, 71, Avenue des Martyrs, Grenoble 38042, France; Faculty of Natural Sciences, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
| | - Gernot A Strohmeier
- acib, Austrian Centre of Industrial Biotechnology GmbH, 8010 Graz, Austria; Institute of Organic Chemistry, NAWI Graz, Graz University of Technology, 8010 Graz, Austria
| | - Melanie Hirz
- Institute of Molecular Biotechnology, NAWI Graz, BioTechMed Graz, Graz University of Technology, 8010 Graz, Austria
| | - Katherine C Thompson
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E 7HX, United Kingdom
| | - Adrian R Rennie
- Centre for Neutron Scattering, Uppsala University, 751 20 Uppsala, Sweden
| | | | - Harald Pichler
- acib, Austrian Centre of Industrial Biotechnology GmbH, 8010 Graz, Austria; Institute of Molecular Biotechnology, NAWI Graz, BioTechMed Graz, Graz University of Technology, 8010 Graz, Austria
| | - Selma Maric
- Biofilms - Research Centre for Biointerfaces and Biomedical Science Department, Faculty of Health and Society, Malmö University, Malmö 20506, Sweden
| | - V Trevor Forsyth
- Institut Laue-Langevin, 71, Avenue des Martyrs, Grenoble 38042, France; Faculty of Natural Sciences, Keele University, Keele, Staffordshire ST5 5BG, United Kingdom
| | - Michael Haertlein
- Institut Laue-Langevin, 71, Avenue des Martyrs, Grenoble 38042, France.
| |
Collapse
|
7
|
Sheridan AJ, Slater JM, Arnold T, Campbell RA, Thompson KC. Changes to DPPC Domain Structure in the Presence of Carbon Nanoparticles. Langmuir 2017; 33:10374-10384. [PMID: 28930468 DOI: 10.1021/acs.langmuir.7b01077] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
DPPC (dipalmitoylphosphatidylcholine) is a disaturated lipid capable of forming closely packed monolayers at the air-liquid interface of the lung and allows the surface tension within the alveoli to reduce to almost zero and thus prevent alveolar collapse. Carbon nanoparticles are formed in natural and man-made combustion events, including diesel engines, and are capable of reaching the alveolar epithelium during breathing. In this work, we have used Brewster angle microscopy and neutron reflectivity to study the effect of differing concentrations of carbon nanoparticles on the structure of DPPC monolayer as the monolayer is subject to compression and expansion. The results show that the inclusion of carbon nanoparticles within a DPPC monolayer affects the formation and structure of the lipid domains. The domains lose their circular structure and show a crenated structure as well as a reduction in overall size of the domains. This change in structure is also evident following expansion of the lipid monolayer, suggesting that some carbon nanoparticles may remain associated with the monolayer. This observation could have an important implication regarding the removal of nanosized airborne pollutants from the human lung.
Collapse
Affiliation(s)
- Alan J Sheridan
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck College, University of London , Malet Street, London WC1E 7HX, U.K
| | - Jonathan M Slater
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck College, University of London , Malet Street, London WC1E 7HX, U.K
| | - Thomas Arnold
- I07, Diamond Light Source, Diamond House, Harwell Science & Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | - Richard A Campbell
- Institut Laue-Langevin, 71 avenue des Martyrs - CS 20156-38042, Grenoble 38000 Cedex 9, France
| | - Katherine C Thompson
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck College, University of London , Malet Street, London WC1E 7HX, U.K
| |
Collapse
|
8
|
Hemming J, Hughes BR, Rennie AR, Tomas S, Campbell RA, Hughes AV, Arnold T, Botchway SW, Thompson KC. Environmental Pollutant Ozone Causes Damage to Lung Surfactant Protein B (SP-B). Biochemistry 2015; 54:5185-97. [PMID: 26270023 PMCID: PMC4571829 DOI: 10.1021/acs.biochem.5b00308] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 07/30/2015] [Indexed: 11/28/2022]
Abstract
Lung surfactant protein B (SP-B) is an essential protein found in the surfactant fluid at the air-water interface of the lung. Exposure to the air pollutant ozone could potentially damage SP-B and lead to respiratory distress. We have studied two peptides, one consisting of the N-terminus of SP-B [SP-B(1-25)] and the other a construct of the N- and C-termini of SP-B [SP-B(1-25,63-78)], called SMB. Exposure to dilute levels of ozone (~2 ppm) of monolayers of each peptide at the air-water interface leads to a rapid reaction, which is evident from an increase in the surface tension. Fluorescence experiments revealed that this increase in surface tension is accompanied by a loss of fluorescence from the tryptophan residue at the interface. Neutron and X-ray reflectivity experiments show that, in contrast to suggestions in the literature, the peptides are not solubilized upon oxidation but rather remain at the interface with little change in their hydration. Analysis of the product material reveals that no cleavage of the peptides occurs, but a more hydrophobic product is slowly formed together with an increased level of oligomerization. We attributed this to partial unfolding of the peptides. Experiments conducted in the presence of phospholipids reveal that the presence of the lipids does not prevent oxidation of the peptides. Our results strongly suggest that exposure to low levels of ozone gas will damage SP-B, leading to a change in its structure. The implication is that the oxidized protein will be impaired in its ability to interact at the air-water interface with negatively charged phosphoglycerol lipids, thus compromising what is thought to be its main biological function.
Collapse
Affiliation(s)
- Joanna
M. Hemming
- Department of Biological Sciences
and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E
7HX, U.K.
| | - Brian R. Hughes
- Department of Biological Sciences
and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E
7HX, U.K.
| | - Adrian R. Rennie
- Materials Physics, Department
of
Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden
| | - Salvador Tomas
- Department of Biological Sciences
and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E
7HX, U.K.
| | - Richard A. Campbell
- Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, 38042 Grenoble Cedex 09, France
| | - Arwel V. Hughes
- ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory,
Harwell Oxford, Didcot, Oxfordshire OX11 0QX, U.K.
| | - Thomas Arnold
- Diamond
Light Source, Harwell
Science and Innovation Campus, Didcot OX11 0DE, U.K.
| | - Stanley W. Botchway
- STFC, Lasers
for Science Facility,
Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory,
Harwell Oxford, Didcot, Oxfordshire OX11 0FA, U.K.
| | - Katherine C. Thompson
- Department of Biological Sciences
and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E
7HX, U.K.
| |
Collapse
|
9
|
Thompson KC, Jones SH, Rennie AR, King MD, Ward AD, Hughes BR, Lucas COM, Campbell RA, Hughes AV. Degradation and rearrangement of a lung surfactant lipid at the air-water interface during exposure to the pollutant gas ozone. Langmuir 2013; 29:4594-4602. [PMID: 23480170 DOI: 10.1021/la304312y] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The presence of unsaturated lipids in lung surfactant is important for proper respiratory function. In this work, we have used neutron reflection and surface pressure measurements to study the reaction of the ubiquitous pollutant gas-phase ozone, O3, with pure and mixed phospholipid monolayers at the air-water interface. The results reveal that the reaction of the unsaturated lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC, with ozone leads to the rapid loss of the terminal C9 portion of the oleoyl strand of POPC from the air-water interface. The loss of the C9 portion from the interface is accompanied by an increase in the surface pressure (decrease in surface tension) of the film at the air-water interface. The results suggest that the portion of the oxidized oleoyl strand that is still attached to the lipid headgroup rapidly reverses its orientation and penetrates the air-water interface alongside the original headgroup, thus increasing the surface pressure. The reaction of POPC with ozone also leads to a loss of material from the palmitoyl strand, but the loss of palmitoyl material occurs after the loss of the terminal C9 portion from the oleoyl strand of the molecule, suggesting that the palmitoyl material is lost in a secondary reaction step. Further experiments studying the reaction of mixed monolayers composed of unsaturated lipid POPC and saturated lipid dipalmitoyl-sn-glycero-3-phosphocholine, DPPC, revealed that no loss of DPPC from the air-water interface occurs, eliminating the possibility that a reactive species such as an OH radical is formed and is able to attack nearby lipid chains. The reaction of ozone with the mixed films does cause a significant change in the surface pressure of the air-water interface. Thus, the reaction of unsaturated lipids in lung surfactant changes and impairs the physical properties of the film at the air-water interface.
Collapse
Affiliation(s)
- Katherine C Thompson
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E 7HX, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Thompson KC, Rennie AR, King MD, Hardman SJO, Lucas COM, Pfrang C, Hughes BR, Hughes AV. Reaction of a phospholipid monolayer with gas-phase ozone at the air-water interface: measurement of surface excess and surface pressure in real time. Langmuir 2010; 26:17295-17303. [PMID: 20883049 DOI: 10.1021/la1022714] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The reaction between gas-phase ozone and monolayers of the unsaturated lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC, on aqueous solutions has been studied in real time using neutron reflection and surface pressure measurements. The reaction between ozone and lung surfactant, which contains POPC, leads to decreased pulmonary function, but little is known about the changes that occur to the interfacial material as a result of oxidation. The results reveal that the initial reaction of ozone with POPC leads to a rapid increase in surface pressure followed by a slow decrease to very low values. The neutron reflection measurements, performed on an isotopologue of POPC with a selectively deuterated palmitoyl strand, reveal that the reaction leads to loss of this strand from the air-water interface, suggesting either solubilization of the product lipid or degradation of the palmitoyl strand by a reactive species. Reactions of (1)H-POPC on D(2)O reveal that the headgroup region of the lipids in aqueous solution is not dramatically perturbed by the reaction of POPC monolayers with ozone supporting degradation of the palmitoyl strand rather than solubilization. The results are consistent with the reaction of ozone with the oleoyl strand of POPC at the air-water interface leading to the formation of OH radicals. The highly reactive OH radicals produced can then go on to react with the saturated palmitoyl strands leading to the formation of oxidized lipids with shorter alkyl tails.
Collapse
Affiliation(s)
- Katherine C Thompson
- Department of Biological Sciences and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
11
|
King MD, Rennie AR, Thompson KC, Fisher FN, Dong CC, Thomas RK, Pfrang C, Hughes AV. Oxidation of oleic acid at the air–water interface and its potential effects on cloud critical supersaturations. Phys Chem Chem Phys 2009; 11:7699-707. [DOI: 10.1039/b906517b] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
12
|
Iqbal A, Wang L, Thompson KC, Lilley DMJ, Norman DG. The structure of cyanine 5 terminally attached to double-stranded DNA: implications for FRET studies. Biochemistry 2008; 47:7857-62. [PMID: 18597488 DOI: 10.1021/bi800773f] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Fluorescence resonance energy transfer, FRET, can be used to obtain long-range distance information for macromolecules and is particularly powerful when used in single-molecule studies. The determination of accurate distances requires knowledge of the fluorophore position with respect to the macromolecule. In this study we have used NMR to determine the structure of the commonly used fluorophore indocarbocyanine-5 (Cy5) covalently attached to the 5'-terminus of double-helical DNA. We find that Cy5 is predominantly stacked onto the end of the duplex, in a manner similar to an additional base pair. This is very similar to the behavior of Cy3 terminally attached to DNA and suggests that the efficiency of energy transfer between Cy3 and Cy5, that are attached to nucleic acids in this way, will exhibit significant dependence on fluorophore orientation.
Collapse
Affiliation(s)
- Asif Iqbal
- Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, UK
| | | | | | | | | |
Collapse
|
13
|
Hardman SJO, Botchway SW, Thompson KC. Evidence for a nonbase stacking effect for the environment-sensitive fluorescent base pyrrolocytosine--comparison with 2-aminopurine. Photochem Photobiol 2008; 84:1473-9. [PMID: 18513237 DOI: 10.1111/j.1751-1097.2008.00368.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyrrolocytosine (PC), is a highly fluorescent analog of the natural nucleobase cytosine. The fluorescence of PC is quenched upon helix formation but the origin of the quenching is not known. We investigated the effects of base stacking in the aqueous phase by following the fluorescence of dinucleotides and trinucleotides containing PC. The quantum yields and lifetimes (ns) (in parenthesis) obtained at 25 degrees C were: PC-T, 0.026 (2.0), PC-C, 0.033 (2.5), PC-A, 0.032 (2.7), PC-G, 0.021 (2.0), T-PC-T, 0.044 (3.0) and G-PC-G, 0.036 (0.65 and 2.6), compared with 0.038 (2.9) for PC and 0.028 (2.1) for the nucleoside triphosphate. The results show that base stacking does not, except in the case of guanine, quench the fluorescence of PC; indeed the increased solvent shielding can enhance the emitted fluorescence. In the case of G-PC-G the guanines do shield the fluorescent base from the solvent but a particular environment of PC between two guanines also appears to allow a rapid nonradiative pathway, suggested to be electron transfer to the excited PC, to depopulate the excited state leading to the shorter fluorescence lifetime.
Collapse
Affiliation(s)
- Samantha J O Hardman
- School of Biological and Chemical Sciences, Birkbeck University of London, London, UK
| | | | | |
Collapse
|
14
|
King MD, Thompson KC, Ward AD, Pfrang C, Hughes BR. Oxidation of biogenic and water-soluble compounds in aqueous and organic aerosol droplets by ozone: a kinetic and product analysis approach using laser Raman tweezers. Faraday Discuss 2008; 137:173-92; discussion 193-204. [DOI: 10.1039/b702199b] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
15
|
Hardman SJO, Thompson KC. Influence of base stacking and hydrogen bonding on the fluorescence of 2-aminopurine and pyrrolocytosine in nucleic acids. Biochemistry 2006; 45:9145-55. [PMID: 16866360 DOI: 10.1021/bi060479t] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fluorescent nucleobase analogues are used extensively to probe the structure and dynamics of nucleic acids. The fluorescence of the adenine analogue 2-aminopurine and the cytosine analogue pyrrolocytosine is significantly quenched when the bases are located in regions of double-stranded nucleic acids. To allow more detailed structural information to be obtained from fluorescence studies using these bases, we have studied the excited-state properties of the bases at the CIS and TDB3LYP level in hydrogen-bonded and base-stacked complexes. The results reveal that the first excited state (the fluorescent state) of a hydrogen-bonded complex containing 2-aminopurine and thymine is just the first excited state of 2-aminopurine alone. However, the same cannot be said for structures in which 2-aminopurine is base stacked with other nucleobases. Stacking causes the molecular orbitals involved in the fluorescence transition to spread over more than one base. The predicted rate for the fluorescence transition is reduced, thus reducing the fluorescence quantum yield. The decrease in radiative rate varies with the stacking arrangement (e.g., A- or B-form DNA) and with the identity of the nucleobase with which 2-aminopurine is stacked. Stacking 2-aminopurine between two guanine moieties is shown to significantly decrease the energy gap between the first and second excited states. We do not find reliable evidence for a low-energy charge-transfer state in any of the systems that were studied. In the case of pyrrolocytosine, base stacking was found to reduce the oscillator strength for the fluorescence transition, but very little spreading of molecular orbitals across more than one base was observed.
Collapse
Affiliation(s)
- Samantha J O Hardman
- School of Biological and Chemical Sciences, Birkbeck University of London, Malet Street, London WC1E 7HX, UK
| | | |
Collapse
|
16
|
Abstract
Pyrrolocytosine is a novel, environment sensitive, fluorescent base that can be used in place of cytosine as a fluorescent marker in nucleic acids. In this work the results of a detailed computational investigation into the hybridization and photochemical properties of the base are reported. The interaction energy of the base pair formed between pyrrolocytosine and guanine, calculated at the MP2/6-31G(d,0.25)//HF/6-31G(d,p) level, was found to be -27.2 kcal mol(-1), comparing very favorably with the value calculated for the cytosine and guanine base pair, -25.8 kcal mol(-1). The wavelengths for the vertical transitions of pyrrolocytosine and cytosine were determined using both the configuration interaction technique, with singly excited configurations (CIS) and time-dependent density functional theory using the B3LYP functional (TDB3LYP). It was found that the spacing between the first pipi state and the first npi state was significantly larger in the case of pyrrolocytosine than cytosine, providing a rationale for the higher fluorescence quantum yield of the former. Hydrogen bonding of pyrrolocytosine to guanine did not affect the predicted fluorescence properties of pyrrolocytosine whereas stacking guanine above pyrrolocytosine, in a manner appropriate to B-form DNA, significantly reduced the predicted fluorescence. Calculations on the two base systems using the TDB3LYP method produced low-lying charge-transfer states which are not predicted when the CIS method is used and are not thought to be physically meaningful.
Collapse
Affiliation(s)
- Katherine C Thompson
- School of Biological and Chemical Sciences, Birkbeck University of London, Malet Street, London WC1E 7HX, U.K
| | | |
Collapse
|
17
|
King MD, Thompson KC, Ward AD. Laser Tweezers Raman Study of Optically Trapped Aerosol Droplets of Seawater and Oleic Acid Reacting with Ozone: Implications for Cloud-Droplet Properties. J Am Chem Soc 2004; 126:16710-1. [PMID: 15612694 DOI: 10.1021/ja044717o] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this communication we report the first use of the Raman laser tweezers technique to trap and hold a mixed droplet of oleic acid and water at atmospheric pressure for 30 min, oxidize the oleic acid on the droplet, follow the decay of reactants and the growth of chemical products using Raman spectroscopy, and monitor the growth in size of the droplet as it becomes more hydrophilic. We demonstrate that the oxidation of organic films on water droplets could have large climatic effects in the atmosphere. We show that cloud-droplet growth and activation of cloud condensation nuclei (to become cloud droplets) is retarded by the presence of an organic film and that chemical oxidation of this film would allow a cloud droplet to grow, reducing cloud albedo by inducing precipitation, and would allow a cloud condensation nucleus to grow to a cloud droplet, thus forming a cloud and increasing the albedo of the Earth.
Collapse
Affiliation(s)
- Martin D King
- Department of Geology, Royal Holloway University of London, Egham, Surrey TW20 0EX, U.K
| | | | | |
Collapse
|
18
|
Beddows DCS, Donovan RJ, Harrison RM, Heal MR, Kinnersley RP, King MD, Nicholson DH, Thompson KC. Correlations in the chemical composition of rural background atmospheric aerosol in the UK determined in real time using time-of-flight mass spectrometry. ACTA ACUST UNITED AC 2004; 6:124-33. [PMID: 14760456 DOI: 10.1039/b311209h] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An aerosol time-of-flight mass spectrometer (ATOFMS) was used to determine, in real time, the size and chemical composition of individual particles in the atmosphere at the remote inland site of Eskdalemuir, Scotland. A total of 51,980 particles, in the size range 0.3-7.4 microm, were detected between the 25th and 30th June 2001. Rapid changes in the number density, size and chemical composition of the atmospheric aerosol were observed. These changes are attributed to two distinct types of air mass; a polluted air mass that had passed over the British mainland before reaching Eskdalemuir, interposed between two cleaner air masses that had arrived directly from the sea. Such changes in the background aerosol could clearly be very important to studies of urban aerosols and attempts at source apportionment. The results of an objective method of data analysis are presented. Correlations were sought between the occurrence of: lithium, potassium, rubidium, caesium, beryllium, strontium, barium, ammonium, amines, nitrate, nitrite, boron, mercury, sulfate, phosphate, fluorine, chlorine, bromine, iodine and carbon (both elemental and organic hydrocarbon) in both fine (d < 2.5 microm) and coarse (d > 2.5 microm) particle fractions. Several previously unreported correlations were observed, for instance between the elements lithium, beryllium and boron. The results suggest that about 2 in 3 of all fine particles (by number rather than by mass), and 1 in 2 of all coarse particles containing carbon, consisted of elemental carbon rather than organic hydrocarbon (although a bias in the sensitivity of the ATOFMS could have affected these numbers). The ratio of the number of coarse particles containing nitrate anions to the number of particles containing chloride anions exceeded unity when the air mass had travelled over the British mainland. The analysis also illustrates that an air mass of marine origin that had travelled slowly over agricultural land can accumulate amines and ammonium.
Collapse
Affiliation(s)
- David C S Beddows
- School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, UK EH9 3JJ
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Paulus LR, Walker DW, Thompson KC. A field test of electret ion chambers for environmental remediation verification. Health Phys 2003; 85:371-376. [PMID: 12938728 DOI: 10.1097/00004032-200309000-00014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In 1999, the State of Idaho INEEL Oversight Program performed a field test to determine if electret ion chambers could be used as a replacement to soil sampling in field survey releases at a remediated radioactively contaminated site. This study compared exposure rates measured using electret ion chambers with gamma spectroscopic analysis results of soil samples collected at the remediated site. Exposure rate measurements were made in 1999 using electret ion chambers at the same locations that INEEL Oversight Program sampled soil in 1998 following MARSSIM protocol. The waste site was divided into nine survey units based upon site history including previous site surveys and physical boundaries. Exposure rate measurements at the remediation site compared well with exposure rate measurements made at reference background locations used for routine environmental monitoring by the State of Idaho indicating that the remedial action met cleanup criteria. A poor correlation between exposure rate measurements and 137Cs concentrations and other discrepancies were observed during this study with respect to measurements made during the 1998 final site survey.
Collapse
Affiliation(s)
- L R Paulus
- State of Idaho INEEL Oversight Program, 900 N. Skyline, Suite C, Idaho Falls, ID 83402, USA.
| | | | | |
Collapse
|
20
|
Paulus LR, Walker DW, Thompson KC. A comparison of desiccant materials used for monitoring atmospheric tritium concentrations in a semi-arid climate. Health Phys 2003; 85:348-356. [PMID: 12938725 DOI: 10.1097/00004032-200309000-00011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Atmospheric tritium monitoring involves the collection of tritiated water vapor by collecting atmospheric moisture from air that is drawn through a bed of desiccant material. This study is a comparison between molecular sieve and silica gel adsorbent media used for atmospheric moisture sampling conducted in the semi-arid climate of the Idaho National Engineering and Environmental Laboratory. Water vapor was collected simultaneously using two columns containing different desiccant materials (one column containing molecular sieve and the other containing silica gel). Data collected during air sampling periods were compared with meteorological data collected, and atmospheric moisture collection efficiencies were determined. Breakthrough of atmospheric moisture past the desiccant material was suspected with both media at elevated temperatures indicating that smaller sample volumes, lower volumetric flow rates, or longer adsorbent columns should be used during summer when ambient temperatures are elevated.
Collapse
Affiliation(s)
- L R Paulus
- State of Idaho INEEL Oversight Program, 900 N. Skyline, Suite C. Idaho Falls, ID 83402, USA.
| | | | | |
Collapse
|
21
|
Thompson KC, Margey P. Hydrogen bonded complexes between nitrogen dioxide, nitric acid, nitrous acid and water with SiH3OH and Si(OH)4. Phys Chem Chem Phys 2003. [DOI: 10.1039/b303507g] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
22
|
Thompson KC, Canosa-Mas CE, Wayne RP. Kinetics and mechanism of the reaction between atomic chlorine and dimethyl selenide; comparison with the reaction between atomic chlorine and dimethyl sulfide. Phys Chem Chem Phys 2002. [DOI: 10.1039/b204657a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
23
|
Dubey JP, Fritz D, Lindsay DS, Shen SK, Kwok OC, Thompson KC. Diclazuril preventive therapy of gamma interferon knockout mice fed Sarcocystis neurona sporocysts. Vet Parasitol 2001; 94:257-64. [PMID: 11137273 DOI: 10.1016/s0304-4017(00)00376-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gamma interferon knockout (KO) mice (n=74) were fed a lethal dose of approximately 1000 sporocysts of the SN15-OP isolate of Sarcocystis neurona. Groups of mice were given pelleted rodent feed containing 50ppm of diclazuril at different times before and after feeding sporocysts. All mice were examined at necropsy and their tissues were examined immunohistochemically for S. neurona infection. Twenty mice were fed sporocysts and given diclazuril starting 5 days before feeding sporocysts and continuing 30-39 days post-infection (p.i.). One mouse died of causes unrelated to S. neurona with no demonstrable parasites; the remaining 19 mice remained clinically normal and S. neurona organisms were not found in their tissues. Sarcocystis neurona organisms were not demonstrable by bioassay of the brains of these 19 mice in uninfected KO mice. Sarcocystis neurona organisms were not found in tissues of five mice treated with diclazuril, starting 7 days after feeding sporocysts and continuing up to 39 days p.i. Therapy was less efficient when diclazuril was given 10 days p.i. Sarcocystis neurona organisms were found in two of 19 mice treated with diclazuril starting 10 days after feeding sporocysts, in two of five mice starting therapy 12 days p.i., and in 10 of 10 mice when treatment was delayed until 15 days p.i. All 15 mice fed S. neurona, but not given diclazuril, developed neural sarcocystosis and were euthanized 22-30 days after feeding sporocysts. Six mice not fed S. neurona, but given diclazuril for 44 days, remained clinically normal. Results indicate that diclazuril can kill the early stages of S. neurona.
Collapse
Affiliation(s)
- J P Dubey
- United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Beltsville Agricultural Research Center, MD 20705-2305, USA.
| | | | | | | | | | | |
Collapse
|
24
|
Canosa-Mas CE, Cotter ESN, Duffy J, Thompson KC, Wayne RP. The reactions of atomic chlorine with acrolein, methacrolein and methyl vinyl ketone. Phys Chem Chem Phys 2001. [DOI: 10.1039/b101434j] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
25
|
Canosa-Mas CE, Dillon TJ, Sidebottom H, Thompson KC, Wayne RP. A study of the OH-initiated oxidation of chlorinated ethenes in the gas phase. Phys Chem Chem Phys 2001. [DOI: 10.1039/b005392i] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
26
|
Elwaer AR, McLeod CW, Thompson KC. On-line separation and determination of bromate in drinking waters using flow injection ICP mass spectrometry. Anal Chem 2000; 72:5725-30. [PMID: 11101254 DOI: 10.1021/ac0007433] [Citation(s) in RCA: 26] [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: 11/30/2022]
Abstract
A flow injection (FI) system with a microcolumn of anion exchanger has been used to effect rapid on-line separation of bromate and bromide prior to quantitation by ICP mass spectrometry. Basic performance studies are described including the effect of key FI parameters, i.e., sample injection volume, carrier stream flow rate, and eluent concentration on system response. The new approach permitted ultratrace determinations of bromate in drinking waters, the main benefits being low limit of detection (0.13 microg/L based on a 500-microL sample injection), rapid analysis time (10 min/sample), and good precision (2.8% at the 5 microg/L level). Accuracy was checked via an EC-sponsored interlaboratory trial.
Collapse
Affiliation(s)
- A R Elwaer
- Centre for Analytical Sciences, Department of Chemistry, University of Sheffield, UK
| | | | | |
Collapse
|
27
|
Thompson KC, Guinamant JL, Ingrand V, Elwaer AR, McLeod CW, Schmitz F, De Swaef G, Quevauviller P. Interlaboratory trial to determine the analytical state-of-the-art of bromate determination in drinking water. J Environ Monit 2000; 2:416-9. [PMID: 11254042 DOI: 10.1039/b004226i] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The new European Directive for water intended for human consumption has established a regulatory level for bromate at 10 microg L(-1). This Maximum Admissible Concentration requires analytical methods with detection limits of a least 2.5 microg L(-1). A project funded by the Standards, Measurements and Testing Programme of the European Commission has enabled the improvement and/or development of methods for the determination of bromate at such concentration levels. This collaborative work was concluded by the organisation of an interlaboratory trial involving 26 European laboratories, which enabled the testing of both a draft ISO Standard method and alternative methods. This paper presents the results of this interlaboratory trial, along with results of a bromate stability study. The progress made with respect to the analytical state-of-the-art for bromate will greatly benefit the quality of measurements carried out in water quality monitoring.
Collapse
|
28
|
Abstract
Ten horses were used in a crossover study to evaluate the effectiveness of eltenac against endotoxaemia. Eltenac (0.5 mg/kg bwt) or saline control was given i.v. then 15 min later, intravenous infusion of endotoxin was begun and continued for 120 min (total dose 100 ng/kg bwt). Horses were monitored for heart and respiratory rates, pulmonary and carotid arterial pressure and core body temperature. Blood was sampled at intervals for measurement of haematological variables and plasma concentrations of lactate, prostanoid metabolites, tumour necrosis factor (TNF) and stress hormones. In comparison with saline-treatment, use of eltenac significantly protected against endotoxin-induced changes in respiratory rate, core temperature, systemic arterial blood pressure (SAP), pulmonary arterial pressure, PCV, and plasma protein, 6-keto prostaglandin F1 alpha, thromboxane B2, epinephrine, and cortisol concentrations. Despite statistical effect of eltenac on SAP, values in both treatment groups remained well above baseline throughout the evaluation period. Significant protective effect of eltenac was not found for heart rate, white blood cell count, plasma lactate concentration or TNF activity. On the basis of these results, it is expected that use of eltenac will provide clinical benefit in horses with naturally occurring endotoxaemia.
Collapse
Affiliation(s)
- R J MacKay
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32610, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Sheffield MW, Barlow SH, Lambert MJ, Hoyal H, Thompson KC, Garbutt M. A qualitative examination of borderline personality disordered (BPD) patients: interpersonal dynamics and underlying paradoxes. J Pers Disord 1999; 13:287-96. [PMID: 10498041 DOI: 10.1521/pedi.1999.13.3.287] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Theoretical conceptualizations of symptomatology in patients with borderline personality disorder (BPD) have noted an inability to integrate contradictory perceptions (splitting, or dichotomous thinking) as a hallmark of the disorder. This study investigated contradictions manifest in the thinking and behavior of BPD patients, using the concept of paradox. A paradox occurs when an apparent contradiction contains an underlying logic which makes the contradiction comprehensible. Using qualitative methods of analysis, this study explored paradoxes evident in 10 BPD patient narratives about relationship events. Specific paradoxes relating to interpersonal conflicts and self-destructiveness are presented, along with the underlying logic of each paradox as described by patients. Implications for treatment are discussed.
Collapse
|
30
|
Abstract
The polymorphism of the angiotensin II antagonist agent MK-996 was studied, with particular emphasis on crystal form stability, solubility, and reproducible crystallization of the drug. X-ray powder diffraction patterns indicated differences in the crystal forms of early research and development lots. Solubility data for the different crystal forms in water at 25 degrees C are in agreement with the solution calorimetry data and indicated that crystalline form I is the thermodynamically stable polymorph of MK-996 under ambient conditions. In contrast to the other polymorphs, form I is reproducibly prepared on both the laboratory and production scale. This study examines methodology to determine the most suitable polymorph for development.
Collapse
Affiliation(s)
- H Jahansouz
- Department of Pharmaceutical Research, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
| | | | | | | |
Collapse
|
31
|
Canosa-Mas CE, King MD, Scarr PJ, Thompson KC, Wayne RP. An experimental study of the gas-phase reactions of the NO3 radical with three sesquiterpenes: isolongifolene, alloisolongifolene, and α-neoclovene. Phys Chem Chem Phys 1999. [DOI: 10.1039/a902034i] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
32
|
Canosa-Mas CE, Carr S, King MD, Shallcross DE, Thompson KC, Wayne RP. A kinetic study of the reactions of NO3 with methyl vinyl ketone, methacrolein, acrolein, methyl acrylate and methyl methacrylate. Phys Chem Chem Phys 1999. [DOI: 10.1039/a904613e] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
33
|
Abstract
The benign superior vena cava syndrome is an uncommon medical emergency. We describe a case of the superior vena cava syndrome caused by suppurative mediastinal lymphadenitis. The organisms isolated from various cultures were group C beta-hemolytic Streptococcus, Fusobacterium species, Corynebacterium species, Eikenella corrodens, and Streptococcus milleri. These anaerobic bacteria are part of the normal flora of the upper respiratory tract and the oral cavity. Anterior mediastinoscopy through the right parasternal approach was used to drain the anterior mediastinal abscess and to establish the etiologic factor.
Collapse
Affiliation(s)
- D Roy
- Department of Internal Medicine, Providence Hospital, Southfield, Michigan, USA
| | | | | |
Collapse
|
34
|
Thompson KC, Trowern A, Fowell A, Marathe M, Haycock C, Arthur MJ, Sheron N. Primary rat and mouse hepatic stellate cells express the macrophage inhibitor cytokine interleukin-10 during the course of activation In vitro. Hepatology 1998; 28:1518-24. [PMID: 9828215 DOI: 10.1002/hep.510280611] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Activation of local tissue macrophages (Kupffer cells) and of quiescent hepatic stellate cells (HSCs) to a myofibroblast phenotype are two key events in liver inflammation and fibrosis. It is known that products of activated macrophages may activate stellate cells. We have hypothesized that the products of activated HSCs may also modulate the activity of Kupffer cells. The cytokine interleukin-10 (IL-10), produced by lymphocytes and macrophages, has profound inhibitory actions on macrophages. Normal rat and mouse HSCs that differentiate in vivo and in vitro to activated myofibroblasts were isolated by enzyme perfusion and density centrifugation with or without centrifugal elutriation, confirmed by vitamin A autofluorescence and positive immunostaining for the myofibroblast markers desmin and smooth muscle actin (SMA). Conditioned media and lysates from these cells were found to down-regulate lipopolysaccharide (LPS)-induced tumor necrosis factor- (TNF-) secretion by the mouse macrophage line RAW 267.4. In highly purified preparations of rat HSCs, messenger RNA (mRNA) for IL-10 was detected by reverse-transcription polymerase chain reaction (RT-PCR), from the time of isolation to up to 120 days of culture on plastic. Long-term cultures of unstimulated mouse HSCs secreted IL-10 protein as detected by immunoblotting and specific enzyme-linked immunosorbent assay (ELISA). IL-10 protein was undetectable by immunohistochemistry in mouse HSCs for the first 3 days in culture. After this, the percentage of IL-10-positive cells increased to 45% at day 7 and 100% by day 14, and expression of IL-10 continued in long-term cultures of up to 120 days. The expression of IL-10 by the stromal cells that govern the fibrotic process in the liver may have important implications for the regulation of inflammation and fibrosis in the liver.
Collapse
Affiliation(s)
- K C Thompson
- University Medicine, Southampton General Hospital, Southampton, UK
| | | | | | | | | | | | | |
Collapse
|
35
|
Hamm D, Turchi P, Johnson JC, Lockwood PW, Thompson KC, Katz T. Determination of an effective dose of eltenac and its comparison with that of flunixin meglumine in horses after experimentally induced carpitis. Am J Vet Res 1997; 58:298-302. [PMID: 9055978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVES To titrate a clinically effective eltenac dosage (0.1, 0.5, and 1.0 mg/kg of body weight), compared with vehicle only, and to compare efficacy of the most effective eltenac dosage with that of 1.1 mg of flunixin meglumine/kg. ANIMALS 40 healthy horses, ranked after model induction on the basis of lameness severity, were randomly assigned to 5 treatment groups, with 4 replicates of 10 horses each. PROCEDURE On day -5, after surgical preparation of the left carpal region, 0.7 ml of Freund's complete adjuvant was injected into the intercarpal space. Horses were observed daily, from the day of carpitis induction to day 0, when stride length was used as the method of ranking horses for randomization to treatment assignment. Treatments were administered i.v. once daily for 3 consecutive days, starting on day 0. Prior to carpitis induction on day -5, and at time 0 (pretreatment), 2, 4, 12, 24, 36, 48, 60, 72, and 96 hours after treatment initiation, resting respiratory rate and pulse, rectal temperature, carpal circumference, carpal flexion angle, stride length, carpal hyperthermia, and signs of carpal pain were recorded. RESULTS Compared with the vehicle and 0.1 mg of eltenac/kg, 0.5 and 1.0 mg/kg caused statistically significant improvements (ie, reduction of carpal circumference, increase in carpal flexion angle, and increase in stride length of the affected limb), but values did not differ significantly between the 2 dosages. Thus, a dose-response plateau for eltenac was reached at 0.5 mg/kg. Comparison with flunixin meglumine at a dosage of 1.1 mg/kg did not indicate significant differences between the 2 treatment groups at the pivotal time of 96 hours for carpal circumference, carpal flexion angle, stride length, carpal hyperthermia, and signs of carpal pain. Adverse reactions were not observed. CLINICAL RELEVANCE Under conditions of this study, a dosage plateau for eltenac was determined (0.5 mg/kg) that was statistically equivalent to eltenac (1.0 mg/kg) and flunixin meglumine (1.1 mg/kg) in a 3-day i.v. dosing regimen.
Collapse
Affiliation(s)
- D Hamm
- Research for Animal Health, Fayetteville, AR 72701, USA
| | | | | | | | | | | |
Collapse
|
36
|
Abstract
A wide variety of drugs or combinations of drugs have the potential to form bezoars. In the majority of patients presenting with bezoars there is a clear predisposing factor. This article highlights those drugs or groups of drugs which have been implicated in bezoar formation. Although bezoars are rare, it is important that the clinician is aware of the possibility of their development, particularly in susceptible individuals. This is because bezoars often develop in the elderly and in those with serious coexistent disease. They may be difficult to diagnose and recourse to laparotomy is frequently required to treat them. As a result, they are associated with a significant morbidity and mortality.
Collapse
|
37
|
Abstract
The morphology and post natal ossification of the fifth, sixth and seventh cervical vertebrae of 51 crossbred puppies (aged from birth to 12 weeks) were examined grossly, histologically and radiographically. At birth there were two centres of ossification, one in the vertebral body and one in the base of each pedicle of the neural arch. By one month of age secondary centres of ossification were present in the cranial and caudal epiphyses of the vertebral body. By two months of age these epiphyseal centres began to show signs of closure. Endochondral ossification of the neural arch occurred from a single centre of ossification within each pedicle with bony fusion of the laminae occurring by one month of age. In addition the dimensions of the neural canal were measured. The difference between the caudal and cranial sagittal diameters of each vertebra was 1 mm or less. It was concluded that, after one month of age, the shape of the neural canal can be influenced only by changes within the physes between the vertebral body and the neural arch or by the remodelling of bone formed by intramembranous ossification.
Collapse
Affiliation(s)
- H M Burbidge
- Department of Veterinary Clinical Sciences, Massey University, Palmerston North, New Zealand
| | | | | |
Collapse
|
38
|
Affiliation(s)
- K C Thompson
- Pharmaceutical Research and Development, Merck, Sharp and Dohme Research Labs, West Point, Pennsylvania 19486
| | | | | | | |
Collapse
|
39
|
Tsai PK, Volkin DB, Dabora JM, Thompson KC, Bruner MW, Gress JO, Matuszewska B, Keogan M, Bondi JV, Middaugh CR. Formulation design of acidic fibroblast growth factor. Pharm Res 1993; 10:649-59. [PMID: 7686672 DOI: 10.1023/a:1018939228201] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The design of an aqueous formulation for acidic fibroblast growth factor (aFGF) requires an understanding of the type of compounds that can either directly or indirectly stabilize the protein. To this end, spectrophotometric turbidity measurements were initially employed to screen the ability of polyanionic ligands, less specific compounds, and variations in solution conditions (temperature and pH) to stabilize aFGF against heat-induced aggregation. It was found that in addition to the well-known protection of aFGF by heparin, a surprisingly wide variety of polyanions (including small sulfated and phosphorylated compounds) also stabilizes aFGF. These polyanionic ligands are capable of raising the temperature at which the protein unfolds by 15-30 degrees C. Many commonly used excipients were also observed to stabilize aFGF in both the presence and the absence of heparin. High concentrations of some of these less specific agents are also able to increase the temperature of aFGF thermal unfolding by as much as 6-12 degrees C as shown by circular dichroism and differential scanning calorimetry. Other compounds were found which protect the chemically labile cysteine residues of aFGF from oxidation. Aqueous formulations of aFGF were thus designed to contain both a polyanionic ligand that enhances structural integrity by binding to the protein and chelating agents (e.g., EDTA) to prevent metal ion-catalyzed oxidation of cysteine residues. While room-temperature storage (30 degrees C) leads to rapid inactivation of aFGF in physiological buffer alone, several of these aFGF formulations are stable in vitro for at least 3 months at 30 degrees C. Three aFGF topical formulations were examined in an impaired diabetic mouse model and were found to be equally capable of accelerating wound healing.
Collapse
Affiliation(s)
- P K Tsai
- Department of Pharmaceutical Research, Merck Research Laboratory, West Point, Pennsylvania 19486
| | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
|
41
|
Copeland RA, Ji H, Halfpenny AJ, Williams RW, Thompson KC, Herber WK, Thomas KA, Bruner MW, Ryan JA, Marquis-Omer D. The structure of human acidic fibroblast growth factor and its interaction with heparin. Arch Biochem Biophys 1991; 289:53-61. [PMID: 1716876 DOI: 10.1016/0003-9861(91)90441-k] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The secondary and tertiary structure of recombinant human acidic fibroblast growth factor (aFGF) has been characterized by a variety of spectroscopic methods. Native aFGF consists of ca. 55% beta-sheet, 20% turn, 10% alpha-helix, and 15% disordered polypeptide as determined by laser Raman, circular dichroism, and Fourier transform infrared spectroscopy; the experimentally determined secondary structure content is in agreement with that calculated by the semi-empirical methods of Chou and Fasman (Chou, P. Y., and Fasman, G. C., 1974, Biochemistry 13, 222-244) and Garnier et al. (Garnier, J. O., et al., 1978, J. Mol. Biol. 120, 97-120). Using the Garnier et al. algorithm, the major secondary structure components of aFGF have been assigned to specific regions of the polypeptide chain. The fluorescence spectrum of native aFGF is unusual in that it is dominated by tyrosine fluorescence despite the presence of a tryptophan residue in the protein. However, tryptophan fluorescence is resolved upon excitation above 295 nm. The degree of tyrosine and tryptophan solvent exposure has been assessed by a combination of ultraviolet absorption, laser Raman, and fluorescence spectroscopy; the results suggest that seven of the eight tyrosine residues are solvent exposed while the single tryptophan is partially inaccessible to solvent in native aFGF, consistent with recent crystallographic data. Denaturation of aFGF by extremes of temperature or pH leads to spectroscopically distinct conformational states in which contributions of tyrosine and tryptophan to the fluorescence spectrum of the protein vary. The protein is unstable at physiological temperatures. Addition of heparin or other sulfated polysaccharides does not affect the spectroscopic characteristics of native aFGF. These polymers do, however, dramatically stabilize the native protein against thermal and acid denaturation as determined by differential scanning calorimetry, circular dichroism, and fluorescence spectroscopy. The interaction of aFGF with such polyanions may play a role in controlling the activity of this growth factor in vivo.
Collapse
Affiliation(s)
- R A Copeland
- Merck Sharp & Dohme Research Laboratories, Rahway, New Jersey 07065
| | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Thompson KC, Roa E J, Romero N T. Anti-tick grasses as the basis for developing practical tropical tick control packages. Trop Anim Health Prod 1978; 10:179-82. [PMID: 705900 DOI: 10.1007/bf02235337] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Of six grass species analysed, Melinis minutiflora (molasses grass) showed the highest anti-tick deterrent properties while Andropogon gayanus (Gamba grass) exhibited the ability to maintain a defined, constantly low, initial host tick infection property and lengthy but low to moderate field tick population. It was concluded that Melinis minutiflora is a species which would best be used in a tick control package within a marginal tick zone while Andropogon gayanus has the advantage within an endemic tick zone.
Collapse
|
43
|
Thompson KC, Todorovic RA, Mateus G, Adams LG. Methods to improve the health of cattle in the tropics: conclusions and economic appraisal. Trop Anim Health Prod 1978; 10:141-4. [PMID: 705891 DOI: 10.1007/bf02235326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The results of the immune responses of immunised and chemoprophylactically treated calves to tick-borne (Boophilus microplus) challenge indicate that the system of immunisation was effective in protecting cattle against Anaplasma marginale, Babesia argentina (bovis), and B. bigemina. However, chemoprophylaxis was effective only against Babesia spp. but not against A. marginale. Both methods showed a substantial advantage over no control system when using native cattle breeds in a zone endemic for bovine anaplasmosis and babesiosis. Based on the net economic gain per calf starting the experiment, sizeable differences were noted at 308 days between the calves in the immunised group, chemoprophylaxis group, tick and gastrointestinal parasite control group and the experiment control group.
Collapse
|
44
|
Thompson KC, Todorovic RA, Mateus G, Adams LG. Methods to improve the health of cattle in the tropics: immunisation and chemoprophylaxis against haemoparasitic infections. Trop Anim Health Prod 1978; 10:75-81. [PMID: 664017 DOI: 10.1007/bf02235310] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A study of methods to improve the health of native cattle in tropical areas of Colombia showed an advantage using immunisation techniques against haemoparasitic infections in comparison with other control methods. The control of anaplasmosis and babesiosis by immunisation of cattle with fully virulent Anaplasma marginale, Babesia argentina and B. bigemina is feasible in tropical cattle when the postimmunisation reaction is controlled by appropriate drug therapy. Chemoprophylaxis was found less effective in controlling haemoparasitic diseases; however, treated was found less effective in controlling haemoparasitic diseases; however, treated cattle surviving the acute stage of infection showed weight gains not significantly different from those of the immunised calves. Both methods were found to be advantageous with calves born and raised in an endemic area of anaplasmosis and babesiosis. Tick and gastrointestinal parasitic control without haemoparasitic control in calves had an advantage over no control system at all. These methods though were inferior to the immunisation and chemoprophylactic techniques.
Collapse
|
45
|
Corrier DE, Cortes JM, Thompson KC, Riaño H, Becerra E, Rodriguez R. A field survey of bovine anaplasmosis, babesiosis and tick vector prevalence in the eastern plains of Colombia. Trop Anim Health Prod 1978; 10:91-2. [PMID: 664020 DOI: 10.1007/bf02235314] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
46
|
Thompson KC, Todorovict RA, Hidalgo RJ. The immune responses to antigenic variants of Babesia bigemina in the bovine. Res Vet Sci 1978; 24:234-7. [PMID: 77539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Four Babesia bigemina stabilates were used to determine the immune response of cattle to acute and chronic blood- and tick-borne infections. Thirty-two intact calves were divided into 16 groups of two and each calf was inoculated with infective B bigemina erythrocytic stabilates. Twenty-eight days later they were challanged with homologous and heterologous stabilates, and monitored for an additional 20 days. The hosts' apparently reduced response to homologous challenge but marked immune response to heterologous challenge indicated antigenic differences between the isolates and confirmed the conclusions reached by examination of the serological data.
Collapse
|
47
|
Thompson KC, Todorovic RA, Hidalgo RJ. Antigenic variation of Babesia bigemina. Res Vet Sci 1977; 23:51-4. [PMID: 905655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The purpose of the study was to determine whether antigenic differences occurred in four stabilates of Babesia bigemina derived from a single purified isolate and propagated as acute and chronic, blood-borne and tick-borne infections in Colombian cattle. Antigens were characterised by means of the complement fixation (CF), gel diffusion (GD), agar gel electrophoresis (AGE) and the indirect haemagglutination tests (IHA). Differences were detected. Acute blood and chronic blood antigens were similar, as were acute tick and chronic tick antigens, when compared by IHA and GD. Similarities were observed between acute blood anc acute tick and between chronic blood and chronic tick when these antigens were compared by AGE and CF.
Collapse
|
48
|
González EF, Todorovic RA, Thompson KC. Immunization against anaplasmosis and babesiosis: Part I. Evaluation of immunization using minimum infective doses under laboratory conditions. Tropenmed Parasitol 1976; 27:427-37. [PMID: 1006801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A method of immunization against anaplasmosis and babesiosis using minimum infective doses was developed under laboratory conditions. Stabilates of Anaplasma marginale stored at -60 degrees C were found infective when diluted 10-fold to 10(-3). Stabilates of Babesia argentina and Babesia bigemina stored under the same conditions were infective when diluted 10-fold to 10(-1). Intact calves inoculated with the above dilutions of stabilates developed moderate parasitemias and recovered from infection without treatment. There was an immune response to vaccination with the formation of specific antibodies to A. marginale, B. bigemina and B. argentina as measured by the complement fixation (CF) test. All calves were found resistant to artificial challenge with lethal doses of the respective parasites.
Collapse
|
49
|
Thompson KC, Godden RG. A simple method for monitoring excessive levels of lead in whole blood using atomic-absorption spectrophotometry and a rapid, direct nebulisation technique. Analyst 1976; 101:174-8. [PMID: 1259176 DOI: 10.1039/an9760100174] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
50
|
|