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Wölk C, Shen C, Hause G, Surya W, Torres J, Harvey RD, Bello G. Membrane Condensation and Curvature Induced by SARS-CoV-2 Envelope Protein. Langmuir 2024; 40:2646-2655. [PMID: 38258382 PMCID: PMC10851660 DOI: 10.1021/acs.langmuir.3c03079] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 01/07/2024] [Accepted: 01/08/2024] [Indexed: 01/24/2024]
Abstract
The envelope (E) protein of SARS-CoV-2 participates in virion encapsulation and budding at the membrane of the endoplasmic reticulum Golgi intermediate compartment (ERGIC). The positively curved membrane topology required to fit an 80 nm viral particle is energetically unfavorable; therefore, viral proteins must facilitate ERGIC membrane curvature alteration. To study the possible role of the E protein in this mechanism, we examined the structural modification of the host lipid membrane by the SARS-CoV-2 E protein using synchrotron-based X-ray methods. Our reflectometry results on solid-supported planar bilayers show that E protein markedly condenses the surrounding lipid bilayer. For vesicles, this condensation effect differs between the two leaflets such that the membrane becomes asymmetric and increases its curvature. The formation of such a curved and condensed membrane is consistent with the requirements to stably encapsulate a viral core and supports a role for E protein in budding during SARS-CoV-2 virion assembly.
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Affiliation(s)
- Christian Wölk
- Pharmaceutical
Technology, Medical Faculty, University
Leipzig, Eilenburger
Straße 15a, 04317 Leipzig, Germany
| | - Chen Shen
- Deutsches
Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Gerd Hause
- Biocenter, Martin-Luther University Halle-Wittenberg, Weinbergweg 22, 06120 Halle (Saale), Germany
| | - Wahyu Surya
- School
of Biological Sciences, Nanyang Technological
University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Jaume Torres
- School
of Biological Sciences, Nanyang Technological
University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Richard D. Harvey
- Division
of Pharmaceutical Chemistry, Department of Pharmaceutical Sciences, University of Vienna, Josef-Holaubek-Platz 2, UZA 2, Vienna 1090, Austria
| | - Gianluca Bello
- Division
of Pharmaceutical Chemistry, Department of Pharmaceutical Sciences, University of Vienna, Josef-Holaubek-Platz 2, UZA 2, Vienna 1090, Austria
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2
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Li F, Harvey RD, Modicano P, Hamdi F, Kyrilis F, Müller S, Gruhle K, Kastritis P, Drescher S, Dailey LA. Investigating bolalipids as solubilizing agents for poorly soluble drugs: Effects of alkyl chain length on solubilization and cytotoxicity. Colloids Surf B Biointerfaces 2022; 212:112369. [PMID: 35123195 DOI: 10.1016/j.colsurfb.2022.112369] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [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: 10/07/2021] [Revised: 01/17/2022] [Accepted: 01/23/2022] [Indexed: 01/31/2023]
Abstract
Synthetic single-chain bolalipids with symmetrical headgroups have shown potential in various pharmaceutical applications, such as the stabilization of liposome bilayers. Despite their amphiphilic character, synthetic bolalipids have not yet been investigated for their suitability as solubilizing agents for poorly soluble drug compounds. In this study, three synthetic single-chain bolalipids with increasing alkyl chain lengths (C22, C24 and C26) were investigated. All three bolalipids were able to achieve an increased solubility of the model drug, mefenamic acid, by approximately 180% in a pH 7.4 buffer compared to only a 102-105% increase achieved by sodium dodecyl sulfate (SDS) or the non-ionic surfactant pegylated hydroxystearate (PEG-HS). Subsequently, interfacial activity of bolalipids and their ability to destabilize liposomal bilayers were investigated. The C22 bolalipid exhibited a consistently lower interfacial activity, which was consistent with its significantly lower cytotoxicity in the macrophage-like cell line, J774. A1, compared to C24 and C26 counterparts. The mean IC50 values of the bolalipids tested (0.035-0.093 mM) were approximately 4-100-fold lower than that of SDS (0.401 mM) or PEG-HS (0.922 mM), with the mechanism of toxicity linked to increased cell membrane permeability, as is expected for surfactants. In summary, evidence from this study shows that decreasing the length of the bolalipid alkyl linker from C26 to C22 resulted in a significantly decreased cytotoxicity with no loss in drug solubilization efficiency.
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Affiliation(s)
- Feng Li
- Department of Pharmaceutical Sciences, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria
| | - Richard D Harvey
- Department of Pharmaceutical Sciences, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria
| | - Paola Modicano
- Institute of Pharmacy, Department of Pharmaceutical Technology and Biopharmaceutics, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle (Saale), Germany
| | - Farzad Hamdi
- Biozentrum, MLU Halle-Wittenberg, Weinbergweg 22, Halle/Saale, Germany; Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, MLU Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany
| | - Fotios Kyrilis
- Biozentrum, MLU Halle-Wittenberg, Weinbergweg 22, Halle/Saale, Germany; Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, MLU Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany
| | - Sindy Müller
- Institute of Pharmacy, Department of Pharmaceutical Chemistry, MLU Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany
| | - Kai Gruhle
- Institute of Pharmacy, Department of Pharmaceutical Chemistry, MLU Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany
| | - Panagiotis Kastritis
- Biozentrum, MLU Halle-Wittenberg, Weinbergweg 22, Halle/Saale, Germany; Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, MLU Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany
| | - Simon Drescher
- Phospholipid Research Center, Im Neuenheimer Feld 515, 69120 Heidelberg, Germany
| | - Lea Ann Dailey
- Department of Pharmaceutical Sciences, University of Vienna, Althanstraße 14, A-1090 Vienna, Austria.
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3
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Kelton K, Greif TR, Meinerding M, Elrod N, Harvey RD. Discrimination and financial, occupational, and emotional well-being in strip club dancers during the COVID-19 pandemic: A call for policy reform. Stigma and Health 2022. [DOI: 10.1037/sah0000368] [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: 11/08/2022]
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Terakosolphan W, Altharawi A, Poonprasartporn A, Harvey RD, Forbes B, Chan KLA. In vitro Fourier transform infrared spectroscopic study of the effect of glycerol on the uptake of beclomethasone dipropionate in living respiratory cells. Int J Pharm 2021; 609:121118. [PMID: 34560211 DOI: 10.1016/j.ijpharm.2021.121118] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 12/01/2022]
Abstract
The quantification of drug in living cells is of increasing interest in pharmaceutical research because of its importance in understanding drug efficacy and toxicity. Label-free in situ measurement methods are advantageous for their ability to obtain chemical and time profiles without the need of labelling or extraction steps. We have previously shown that Fourier transform infrared (FTIR) spectroscopy has the potential to quantify drug in situ within living cells at micromolar level when a simple solution of drug was added to the medium. The purpose of this study was to demonstrate that the approach can evaluate more complex systems such as the effect of membrane modification by a formulation on drug uptakes. The inhaled corticosteroid, beclomethasone dipropionate (BDP), in Calu-3 respiratory epithelial cells in the absence and presence of glycerol, an excipient in some inhaled medicines was used as the model system. The FTIR method was first validated for limit of detection (LOD) and quantification (LOQ) according to published guidelines and the LOQ was found to be ∼ 20 μM, good enough to quantify BDP in the living cell. The uptake of BDP by living Calu-3 cells was found to be reduced in the presence of glycerol as expected due to the stiffening of the cell membrane by the presence of glycerol in the formulation. This study demonstrates the valuable analytical capability of live-cell FTIR to study the effect of formulation on drug transport in lungs and to evaluate drug availability to intracellular targets. We conclude that FTIR has potential to contribute widely at the frontier of live-cell studies.
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Affiliation(s)
- Wachirun Terakosolphan
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom
| | - Ali Altharawi
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom; Department of Pharmaceutical Chemistry, College of Pharmacy, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
| | | | - Richard D Harvey
- Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Althanstraße 14 (UZA II), 1090 Wien, Austria
| | - Ben Forbes
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom
| | - K L Andrew Chan
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom.
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Chakrabarty RK, Beeler P, Liu P, Goswami S, Harvey RD, Pervez S, van Donkelaar A, Martin RV. Ambient PM 2.5 exposure and rapid spread of COVID-19 in the United States. Sci Total Environ 2021; 760:143391. [PMID: 33250247 PMCID: PMC7651233 DOI: 10.1016/j.scitotenv.2020.143391] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [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: 08/21/2020] [Revised: 10/19/2020] [Accepted: 10/22/2020] [Indexed: 05/12/2023]
Abstract
It has been posited that populations being exposed to long-term air pollution are more susceptible to COVID-19. Evidence is emerging that long-term exposure to ambient PM2.5 (particulate matter with aerodynamic diameter 2.5 μm or less) associates with higher COVID-19 mortality rates, but whether it also associates with the speed at which the disease is capable of spreading in a population is unknown. Here, we establish the association between long-term exposure to ambient PM2.5 in the United States (US) and COVID-19 basic reproduction ratio R0- a dimensionless epidemic measure of the rapidity of disease spread through a population. We inferred state-level R0 values using a state-of-the-art susceptible, exposed, infected, and recovered (SEIR) model initialized with COVID-19 epidemiological data corresponding to the period March 2-April 30. This period was characterized by a rapid surge in COVID-19 cases across the US states, implementation of strict social distancing measures, and a significant drop in outdoor air pollution. We find that an increase of 1 μg/m3 in PM2.5 levels below current national ambient air quality standards associates with an increase of 0.25 in R0 (95% CI: 0.048-0.447). A 10% increase in secondary inorganic composition, sulfate-nitrate-ammonium, in PM2.5 associates with ≈10% increase in R0 by 0.22 (95% CI: 0.083-0.352), and presence of black carbon (soot) in the ambient environment moderates this relationship. We considered several potential confounding factors in our analysis, including gaseous air pollutants and socio-economical and meteorological conditions. Our results underscore two policy implications - first, regulatory standards need to be better guided by exploring the concentration-response relationships near the lower end of the PM2.5 air quality distribution; and second, pollution regulations need to be continually enforced for combustion emissions that largely determine secondary inorganic aerosol formation.
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Affiliation(s)
- Rajan K Chakrabarty
- Center for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA; Institute for Public Health, Washington University in St. Louis, St. Louis, MO 63130, USA.
| | - Payton Beeler
- Center for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Pai Liu
- Center for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Spondita Goswami
- Experimental Psychology Program, Department of Psychology, Saint Louis University, St. Louis, MO 63108, USA
| | - Richard D Harvey
- Experimental Psychology Program, Department of Psychology, Saint Louis University, St. Louis, MO 63108, USA
| | - Shamsh Pervez
- School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh 492010, India
| | - Aaron van Donkelaar
- Center for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA; Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Randall V Martin
- Center for Aerosol Science and Engineering, Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA
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Saleh MM, Woods A, Harvey RD, Young AR, Jones SA. Nanomaterials fusing with the skin: Alpha-tocopherol phosphate delivery into the viable epidermis to protect against ultraviolet radiation damage. Int J Pharm 2021; 594:120000. [PMID: 33166585 DOI: 10.1016/j.ijpharm.2020.120000] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [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: 08/09/2020] [Revised: 10/16/2020] [Accepted: 10/17/2020] [Indexed: 11/15/2022]
Abstract
Vitamin E (alpha tocopherol, α-T) is an important skin antioxidant, but its penetration into the viable epidermis, where it acts, is very limited. This study investigated if phosphorylating α-tocopherol (α-TP) to form a provitamin, improved its interactions with skin, its passage into the tissue, and thus its ability to protect the skin from ultraviolet radiation (UVR) damage. At pH 7.4, when the α-TPO4-1 microspecies predominated in solution, dynamic light scattering measurements showed that α-TP formed nanoaggregates with a median hydrodynamic diameter of 9 nm (Critical aggregation constant, CAC, - 4.2 mM). At 9.0 when the α-TPO4-2 microspecies predominated there was no aggregation. The passage of α-TP nanoaggregates through regenerated cellulose membranes was significantly slower than the α-TP monomers (at pH 9) suggesting that aggregation slowed diffusion. However, a lotion formulation containing the nanoaggregates delivered more α-TP into the skin compared to the formulation containing the monomers. In addition, the nanosized α-TP aggregates delivered 8-fold more active into the stratum corneum (SC) (252.2 μg/cm2 vs 29.5 μg/cm2) and 4 fold more active into the epidermis (85.1 μg/cm2 vs 19 μg/cm2, respectively, p < 0.05) compared to α-T. Langmuir subphase injection studies at pH 7.4 (surface pressure 10 mN m-1) showed that the α-TP nanoaggregates more readily fused with the SC compared to the monomers and the membrane compression studies demonstrated that α-TP fluidised the SC lipids. Together the fusion with the SC and its fluidisation were proposed as the causes of the better α-TP penetration into the skin, which enhanced potential of α-TP to protect from UVR-induced skin damage compared to α-T.
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Affiliation(s)
- Mais M Saleh
- Department of Pharmaceutics and Pharmaceutical Technology, School of Pharmacy, The University of Jordan, Amman 11942, Jordan
| | - Arcadia Woods
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, Franklin-Wilkins Building, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | - Richard D Harvey
- Department of Pharmaceutical Chemistry, University of Vienna, Althanstraße 14, Vienna, Austria
| | - Antony R Young
- St John's Institute of Dermatology, King's College London, Guy's Hospital, London SE1 9RT, UK
| | - Stuart A Jones
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, Franklin-Wilkins Building, King's College London, 150 Stamford Street, London SE1 9NH, UK.
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7
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Pabois O, Ziolek RM, Lorenz CD, Prévost S, Mahmoudi N, Skoda MWA, Welbourn RJL, Valero M, Harvey RD, Grundy MML, Wilde PJ, Grillo I, Gerelli Y, Dreiss CA. Morphology of bile salts micelles and mixed micelles with lipolysis products, from scattering techniques and atomistic simulations. J Colloid Interface Sci 2020; 587:522-537. [PMID: 33189321 DOI: 10.1016/j.jcis.2020.10.101] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [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: 09/29/2020] [Revised: 10/23/2020] [Accepted: 10/25/2020] [Indexed: 12/17/2022]
Abstract
HYPOTHESES Bile salts (BS) are biosurfactants released into the small intestine, which play key and contrasting roles in lipid digestion: they adsorb at interfaces and promote the adsorption of digestive enzymes onto fat droplets, while they also remove lipolysis products from that interface, solubilising them into mixed micelles. Small architectural variations on their chemical structure, specifically their bile acid moiety, are hypothesised to underlie these conflicting functionalities, which should be reflected in different aggregation and solubilisation behaviour. EXPERIMENTS The micellisation of two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), which differ by one hydroxyl group on the bile acid moiety, was assessed by pyrene fluorescence spectroscopy, and the morphology of aggregates formed in the absence and presence of fatty acids (FA) and monoacylglycerols (MAG) - typical lipolysis products - was resolved by small-angle X-ray/neutron scattering (SAXS, SANS) and molecular dynamics simulations. The solubilisation by BS of triacylglycerol-incorporating liposomes - mimicking ingested lipids - was studied by neutron reflectometry and SANS. FINDINGS Our results demonstrate that BS micelles exhibit an ellipsoidal shape. NaTDC displays a lower critical micellar concentration and forms larger and more spherical aggregates than NaTC. Similar observations were made for BS micelles mixed with FA and MAG. Structural studies with liposomes show that the addition of BS induces their solubilisation into mixed micelles, with NaTDC displaying a higher solubilising capacity.
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Affiliation(s)
- Olivia Pabois
- Institut Laue-Langevin, Grenoble 38000, France; Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom.
| | - Robert M Ziolek
- Department of Physics, King's College London, London WC2R 2LS, United Kingdom.
| | - Christian D Lorenz
- Department of Physics, King's College London, London WC2R 2LS, United Kingdom.
| | | | - Najet Mahmoudi
- ISIS Neutron & Muon Source, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom.
| | - Maximilian W A Skoda
- ISIS Neutron & Muon Source, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom.
| | - Rebecca J L Welbourn
- ISIS Neutron & Muon Source, STFC Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom.
| | - Margarita Valero
- Department of Physical Chemistry, University of Salamanca, Salamanca 37007, Spain.
| | - Richard D Harvey
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna A-1090, Austria.
| | | | - Peter J Wilde
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, United Kingdom.
| | | | - Yuri Gerelli
- Institut Laue-Langevin, Grenoble 38000, France; Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona 60131, Italy.
| | - Cécile A Dreiss
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom.
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Pabois O, Lorenz CD, Harvey RD, Grillo I, Grundy MML, Wilde PJ, Gerelli Y, Dreiss CA. Corrigendum to 'Molecular insights into the behaviour of bile salts at interfaces: a key to their role in lipid digestion'. [Journal of Colloid and Interface Science 556 (2019) 266-277]. J Colloid Interface Sci 2020; 568:282-283. [PMID: 32199634 DOI: 10.1016/j.jcis.2020.03.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Olivia Pabois
- Institut Laue-Langevin, Grenoble 38000, France; Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom
| | - Christian D Lorenz
- Department of Physics, King's College London, London WC2R 2LS, United Kingdom
| | - Richard D Harvey
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale) 06099, Germany
| | | | - Myriam M-L Grundy
- School of Agriculture, Policy and Development, University of Reading, Reading RG6 6AR, United Kingdom
| | - Peter J Wilde
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UA, United Kingdom
| | | | - Cécile A Dreiss
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom.
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9
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Vandera KKA, Picconi P, Valero M, González-Gaitano G, Woods A, Zain NMM, Bruce KD, Clifton LA, Skoda MWA, Rahman KM, Harvey RD, Dreiss CA. Antibiotic-in-Cyclodextrin-in-Liposomes: Formulation Development and Interactions with Model Bacterial Membranes. Mol Pharm 2020; 17:2354-2369. [DOI: 10.1021/acs.molpharmaceut.0c00096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Kalliopi-Kelli A. Vandera
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Pietro Picconi
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Margarita Valero
- Department of Physical Chemistry, University of Salamanca, ES E-37007 Salamanca, Spain
| | | | - Arcadia Woods
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Nur Masirah M. Zain
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Kenneth D. Bruce
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Luke A. Clifton
- Rutherford Appleton Laboratory, ISIS, 1-27, R3, Harwell Campus, Didcot OX11 0QX, U.K
| | | | - Khondaker Miraz Rahman
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Richard D. Harvey
- Department of Pharmaceutical Chemistry, University of Vienna, Althanstraße 14, Vienna, Austria
| | - Cécile A. Dreiss
- School of Cancer & Pharmaceutical Science, Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
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10
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Wölk C, Youssef H, Guttenberg T, Marbach H, Vizcay‐Barrena G, Shen C, Brezesinski G, Harvey RD. Phase Diagram for a Lysyl-Phosphatidylglycerol Analogue in Biomimetic Mixed Monolayers with Phosphatidylglycerol: Insights into the Tunable Properties of Bacterial Membranes. Chemphyschem 2020; 21:702-706. [PMID: 32065707 PMCID: PMC7216935 DOI: 10.1002/cphc.202000026] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [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: 01/09/2020] [Revised: 02/12/2020] [Indexed: 12/13/2022]
Abstract
Ion pairing between the major phospholipids of the Staphylococcus aureus plasma membrane (phosphatidylglycerol - PG and lysyl-phosphatidylglycerol - LPG) confers resistance to antimicrobial peptides and other antibiotics. We developed 3adLPG, a stable synthetic analogue which can substitute for the highy-labile native LPG, in biophysical experiments examining the membrane-protecting role of lipid ion pairing, in S. aureus and other important bacteria. Here we examine the surface charge and lipid packing characteristics of synthetic biomimetic mixtures of DPPG and DP3adLPG in Langmuir monolayers, using a combination of complementary surface-probing techniques such as infrared reflection-absorption spectroscopy and grazing-incidence x-ray diffraction. The resultant phase diagram for the ion paired lipids sheds light on the mixing behavior of lipids in monolayer models of resistant phenotype bacterial membranes, and provides a platform for future biophysical studies.
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Affiliation(s)
- Christian Wölk
- Institute of PharmacyLeipzig UniversityBrüderstraße 3404103LeipzigGermany
| | - Hala Youssef
- Department of Chemistry and BiochemistryConcordia University7141 Sherbrooke Street WestMontrealCanada
| | - Thomas Guttenberg
- Institute of PharmacyMartin-Luther-University Halle-WittenbergKurt-Mothes-Str. 306120Halle (Saale)Germany
| | - Helene Marbach
- Institute of MicrobiologyUniversity of Veterinary MedicineVeterinärplatz 11210ViennaAustria
| | - Gema Vizcay‐Barrena
- Centre for Ultrastructural ImagingKing's College LondonGuy's CampusLondonSE1 1ULUK
| | - Chen Shen
- DESY Photon Science22607HamburgGermany
| | - Gerald Brezesinski
- Max Planck Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
| | - Richard D. Harvey
- Institute of PharmacyMartin-Luther-University Halle-WittenbergKurt-Mothes-Str. 306120Halle (Saale)Germany
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11
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Pabois O, Antoine-Michard A, Zhao X, Omar J, Ahmed F, Alexis F, Harvey RD, Grillo I, Gerelli Y, Grundy MML, Bajka B, Wilde PJ, Dreiss CA. Interactions of bile salts with a dietary fibre, methylcellulose, and impact on lipolysis. Carbohydr Polym 2020; 231:115741. [PMID: 31888817 DOI: 10.1016/j.carbpol.2019.115741] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 09/10/2019] [Revised: 12/10/2019] [Accepted: 12/13/2019] [Indexed: 12/13/2022]
Abstract
Methylcellulose (MC) has a demonstrated capacity to reduce fat absorption, hypothetically through bile salt (BS) activity inhibition. We investigated MC cholesterol-lowering mechanism, and compared the influence of two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), which differ slightly by their architecture and exhibit contrasting functions during lipolysis. BS/MC bulk interactions were investigated by rheology, and BS behaviour at the MC/water interface studied with surface pressure and ellipsometry measurements. In vitro lipolysis studies were performed to evaluate the effect of BS on MC-stabilised emulsion droplets microstructure, with confocal microscopy, and free fatty acids release, with the pH-stat method. Our results demonstrate that BS structure dictates their interactions with MC, which, in turn, impact lipolysis. Compared to NaTC, NaTDC alters MC viscoelasticity more significantly, which may correlate with its weaker ability to promote lipolysis, and desorbs from the interface at lower concentrations, which may explain its higher propensity to destabilise emulsions.
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Affiliation(s)
- Olivia Pabois
- Institut Laue-Langevin, Grenoble, 38000, France; Institute of Pharmaceutical Science, King's College London, London, SE1 9NH, United Kingdom.
| | | | - Xi Zhao
- Institute of Pharmaceutical Science, King's College London, London, SE1 9NH, United Kingdom.
| | - Jasmin Omar
- Institute of Pharmaceutical Science, King's College London, London, SE1 9NH, United Kingdom.
| | - Faizah Ahmed
- Institute of Pharmaceutical Science, King's College London, London, SE1 9NH, United Kingdom.
| | | | - Richard D Harvey
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), 06099, Germany.
| | | | - Yuri Gerelli
- Institut Laue-Langevin, Grenoble, 38000, France.
| | - Myriam M-L Grundy
- School of Agriculture, Policy and Development, University of Reading, Reading, RG6 6AR, United Kingdom.
| | - Balazs Bajka
- Department of Nutritional Sciences, King's College London, London, SE1 9NH, United Kingdom.
| | - Peter J Wilde
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA, United Kingdom.
| | - Cécile A Dreiss
- Institute of Pharmaceutical Science, King's College London, London, SE1 9NH, United Kingdom.
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Wölk C, Hause G, Gutowski O, Harvey RD, Brezesinski G. Enhanced chain packing achieved via putative headgroup ion-triplet formation in binary anionic lipid/cationic surfactant mixed monolayers. Chem Phys Lipids 2019; 225:104827. [DOI: 10.1016/j.chemphyslip.2019.104827] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/16/2019] [Accepted: 09/17/2019] [Indexed: 11/25/2022]
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13
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Pabois O, Lorenz CD, Harvey RD, Grillo I, Grundy MML, Wilde PJ, Gerelli Y, Dreiss CA. Molecular insights into the behaviour of bile salts at interfaces: a key to their role in lipid digestion. J Colloid Interface Sci 2019; 556:266-277. [PMID: 31450021 DOI: 10.1016/j.jcis.2019.08.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [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: 04/04/2019] [Revised: 06/21/2019] [Accepted: 08/03/2019] [Indexed: 11/19/2022]
Abstract
HYPOTHESES Understanding the mechanisms underlying lipolysis is crucial to address the ongoing obesity crisis and associated cardiometabolic disorders. Bile salts (BS), biosurfactants present in the small intestine, play key roles in lipid digestion and absorption. It is hypothesised that their contrasting functionalities - adsorption at oil/water interfaces and shuttling of lipolysis products away from these interfaces - are linked to their structural diversity. We investigate the interfacial films formed by two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), differing by the presence or absence of a hydroxyl group on their steroid skeleton. EXPERIMENTS Their adsorption behaviour at the air/water interface and interaction with a phospholipid monolayer - used to mimic a fat droplet interface - were assessed by surface pressure measurements and ellipsometry, while interfacial morphologies were characterised in the lateral and perpendicular directions by Brewster angle microscopy, X-ray and neutron reflectometry, and molecular dynamics simulations. FINDINGS Our results provide a comprehensive molecular-level understanding of the mechanisms governing BS interfacial behaviour. NaTC shows a higher affinity for the air/water and lipid/water interfaces, and may therefore favour enzyme adsorption, whereas NaTDC exhibits a higher propensity for desorption from these interfaces, and may thus more effectively displace hydrolysis products from the interface, through dynamic exchange.
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Affiliation(s)
- Olivia Pabois
- Institut Laue-Langevin, Grenoble 38000, France; Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom.
| | - Christian D Lorenz
- Department of Physics, King's College London, London WC2R 2LS, United Kingdom.
| | - Richard D Harvey
- Institut für Pharmazie, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale) 06099, Germany.
| | | | - Myriam M-L Grundy
- School of Agriculture, Policy and Development, University of Reading, Reading RG6 6AR, United Kingdom.
| | - Peter J Wilde
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UA, United Kingdom.
| | | | - Cécile A Dreiss
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, United Kingdom.
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14
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Harper RA, Carpenter GH, Proctor GB, Harvey RD, Gambogi RJ, Geonnotti AR, Hider R, Jones SA. Diminishing biofilm resistance to antimicrobial nanomaterials through electrolyte screening of electrostatic interactions. Colloids Surf B Biointerfaces 2019; 173:392-399. [DOI: 10.1016/j.colsurfb.2018.09.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 08/30/2018] [Accepted: 09/08/2018] [Indexed: 02/06/2023]
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15
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Marbach H, Vizcay-Barrena G, Memarzadeh K, Otter JA, Pathak S, Allaker RP, Harvey RD, Edgeworth JD. Tolerance of MRSA ST239-TW to chlorhexidine-based decolonization: Evidence for keratinocyte invasion as a mechanism of biocide evasion. J Infect 2018; 78:119-126. [PMID: 30367885 DOI: 10.1016/j.jinf.2018.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [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: 07/15/2018] [Revised: 09/30/2018] [Accepted: 10/20/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Information on genetic determinants of chlorhexidine tolerance (qacA carriage and MIC) in vitro is available, although evidence of the clinical impact and mechanisms remain poorly understood. We investigated why, following chlorhexidine intervention, prevalent epidemic MRSA ST22 and ST36 clones declined at an ICU, whilst an ST239-TW clone did not. The chlorhexidine tolerant ST239-TW phenotypes were assessed for their protein binding, cell adhesion and intracellular uptake potential. METHODS Six ST22, ST36 and ST239-TW bloodstream infection isolates with comparable chlorhexidine MICs were selected from a 2-year outbreak in an ICU at Guy's and St. Thomas' Hospital. Isolates were tested for fibrinogen and fibronectin binding, and adhesion/internalization into human keratinocytes with and without biocide. RESULTS Binding to fibrinogen and fibronectin, adhesion and intracellular uptake within keratinocytes (P < 0.001) and intracellular survival in keratinocytes under chlorhexidine pressure (ST22 3.18%, ST36 4.57% vs ST239-TW 12.79%; P < 0.0001) was consistently higher for ST239-TW. CONCLUSIONS We present evidence that MRSA clones with similarly low in vitro tolerance to chlorhexidine exhibit different in vivo susceptibilities. The phenomenon of S. aureus adhesion and intracellular uptake into keratinocytes could therefore be regarded as an additional mechanism of chlorhexidine tolerance, enabling MRSA to evade infection control measures.
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Affiliation(s)
- Helene Marbach
- Faculty of Life Sciences and Medicine, Institute of Pharmaceutical Science, King's College London, UK
| | - Gema Vizcay-Barrena
- Centre for Ultrastructural Imaging, King's College London, Guy's Campus, London, UK
| | - Kaveh Memarzadeh
- Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Jonathan A Otter
- Department of Infectious Diseases, Centre for Clinical Infection and Diagnostics Research (CIDR), King's College London & Guy's and St. Thomas' NHS Foundation Trust (GSTT), London, UK
| | - Smriti Pathak
- Department of Infectious Diseases, Centre for Clinical Infection and Diagnostics Research (CIDR), King's College London & Guy's and St. Thomas' NHS Foundation Trust (GSTT), London, UK
| | - Robert P Allaker
- Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Richard D Harvey
- Faculty of Life Sciences and Medicine, Institute of Pharmaceutical Science, King's College London, UK.
| | - Jonathan D Edgeworth
- Department of Infectious Diseases, Centre for Clinical Infection and Diagnostics Research (CIDR), King's College London & Guy's and St. Thomas' NHS Foundation Trust (GSTT), London, UK
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16
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Abstract
Biorelevant fluids are required to enable meaningful in vitro experimental determinations of the biopharmaceutical properties of inhaled medicines, e.g. drug solubility, particle dissolution, cellular uptake. Our aim was to develop a biorelevant simulated lung fluid (SLF) with a well-defined composition and evidence-based directions for use. The SLF contained dipalmitoylphosphotidylcholine, dipalmitoylphosphatidylglycerol, cholesterol, albumin, IgG, transferrin and antioxidants. Freshly made SLF had pH 7.2, viscosity 1.138 × 10−3 Pa s, conductivity 14.5 mS/m, surface tension 54.9 mN/m and density 0.999 g/cm3. Colour, surface tension and conductivity were the most sensitive indicators of product deterioration. The simulant was stable for 24 h and 48 h at 37 °C and 21 °C, respectively, (in-use stability) and for 14 days when stored in a refrigerator (storage stability). To extend stability, the SLF was vacuum freeze-dried in batches to produce lyophilised powder that can be reconstituted readily when needed at the point of use. In conclusion, we have reported the composition and manufacture of a biorelevant, synthetic SLF, provided a detailed physico-chemical characterisation and recommendations for how to store and use a product that can be used to generate experimental data to provide inputs to computational models that predict drug bioavailability in the lungs.
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Affiliation(s)
- Mireille Hassoun
- King's College London, Institute of Pharmaceutical Science, London, SE1 9NH, UK
| | - Paul G Royall
- King's College London, Institute of Pharmaceutical Science, London, SE1 9NH, UK
| | - Mark Parry
- Intertek-Melbourn Scientific Limited, Melbourn, SG8 6DN, UK
| | - Richard D Harvey
- Institute of Pharmacy, Martin-Luther-Universität Halle-Wittenberg, 06108, Halle (Saale), Germany
| | - Ben Forbes
- King's College London, Institute of Pharmaceutical Science, London, SE1 9NH, UK
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Terakosolphan W, Trick JL, Royall PG, Rogers SE, Lamberti O, Lorenz CD, Forbes B, Harvey RD. Glycerol Solvates DPPC Headgroups and Localizes in the Interfacial Regions of Model Pulmonary Interfaces Altering Bilayer Structure. Langmuir 2018; 34:6941-6954. [PMID: 29738253 DOI: 10.1021/acs.langmuir.8b00866] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The inclusion of glycerol in formulations for pulmonary drug delivery may affect the bioavailability of inhaled steroids by retarding their transport across the lung epithelium. The aim of this study was to evaluate whether the molecular interactions of glycerol with model pulmonary interfaces provide a biophysical basis for glycerol modifying inhaled drug transport. Dipalmitoylphosphatidylcholine (DPPC) monolayers and liposomes were used as model pulmonary interfaces, in order to examine the effects of bulk glycerol (0-30% w/w) on their structures and dynamics using complementary biophysical measurements and molecular dynamics (MD) simulations. Glycerol was found to preferentially interact with the carbonyl groups in the interfacial region of DPPC and with phosphate and choline in the headgroup, thus causing an increase in the size of the headgroup solvation shell, as evidenced by an expansion of DPPC monolayers (molecular area increased from 52 to 68 Å2) and bilayers seen in both Langmuir isotherms and MD simulations. Both small angle neutron scattering and MD simulations indicated a reduction in gel phase DPPC bilayer thickness by ∼3 Å in 30% w/w glycerol, a phenomenon consistent with the observation from FTIR data, that glycerol caused the lipid headgroup to remain oriented parallel to the membrane plane in contrast to its more perpendicular conformation adopted in pure water. Furthermore, FTIR measurements suggested that the terminal methyl groups of the DPPC acyl chains were constrained in the presence of glycerol. This observation is supported by MD simulations, which predict bridging between adjacent DPPC headgroups by glycerol as a possible source of its putative membrane stiffening effect. Collectively, these data indicate that glycerol preferentially solvates DPPC headgroups and localizes in specific areas of the interfacial region, resulting in structural changes to DPPC bilayers which may influence cell permeability to drugs.
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Affiliation(s)
- Wachirun Terakosolphan
- School of Cancer and Pharmaceutical Sciences , King's College London , London SE1 9NH , United Kingdom
| | - Jemma L Trick
- Department of Physics , King's College London , London WC2R 2LS , United Kingdom
| | - Paul G Royall
- School of Cancer and Pharmaceutical Sciences , King's College London , London SE1 9NH , United Kingdom
| | - Sarah E Rogers
- Rutherford Appleton Laboratory , ISIS Facility , Chilton , Oxfordshire OX11 0QX , United Kingdom
| | - Olimpia Lamberti
- Department of Physics , King's College London , London WC2R 2LS , United Kingdom
| | - Christian D Lorenz
- Department of Physics , King's College London , London WC2R 2LS , United Kingdom
| | - Ben Forbes
- School of Cancer and Pharmaceutical Sciences , King's College London , London SE1 9NH , United Kingdom
| | - Richard D Harvey
- Institute of Pharmacy , Martin-Luther-University Halle-Wittenberg , Halle (Saale) , 06099 , Germany
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18
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Urbano L, Clifton L, Ku HK, Kendall-Troughton H, Vandera KKA, Matarese BFE, Abelha T, Li P, Desai T, Dreiss CA, Barker RD, Green MA, Dailey LA, Harvey RD. Influence of the Surfactant Structure on Photoluminescent π-Conjugated Polymer Nanoparticles: Interfacial Properties and Protein Binding. Langmuir 2018; 34:6125-6137. [PMID: 29726688 DOI: 10.1021/acs.langmuir.8b00561] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
π-Conjugated polymer nanoparticles (CPNs) are under investigation as photoluminescent agents for diagnostics and bioimaging. To determine whether the choice of surfactant can improve CPN properties and prevent protein adsorption, five nonionic polyethylene glycol alkyl ether surfactants were used to produce CPNs from three representative π-conjugated polymers. The surfactant structure did not influence size or yield, which was dependent on the nature of the conjugated polymer. Hydrophobic interaction chromatography, contact angle, quartz crystal microbalance, and neutron reflectivity studies were used to assess the affinity of the surfactant to the conjugated polymer surface and indicated that all surfactants were displaced by the addition of a model serum protein. In summary, CPN preparation methods which rely on surface coating of a conjugated polymer core with amphiphilic surfactants may produce systems with good yields and colloidal stability in vitro, but may be susceptible to significant surface alterations in physiological fluids.
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Affiliation(s)
- Laura Urbano
- School of Cancer & Pharmaceutical Sciences , King's College London , 150 Stamford Street , London SE1 9NH , U.K
| | - Luke Clifton
- ISIS Spallation Neutron Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 0QX , U.K
| | - Hoi Ki Ku
- School of Cancer & Pharmaceutical Sciences , King's College London , 150 Stamford Street , London SE1 9NH , U.K
| | - Hannah Kendall-Troughton
- School of Cancer & Pharmaceutical Sciences , King's College London , 150 Stamford Street , London SE1 9NH , U.K
| | - Kalliopi-Kelli A Vandera
- School of Cancer & Pharmaceutical Sciences , King's College London , 150 Stamford Street , London SE1 9NH , U.K
| | - Bruno F E Matarese
- Department of Chemistry , Imperial College London , London SW7 2AZ , U.K
| | - Thais Abelha
- School of Cancer & Pharmaceutical Sciences , King's College London , 150 Stamford Street , London SE1 9NH , U.K
| | - Peixun Li
- ISIS Spallation Neutron Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus , Didcot , Oxfordshire OX11 0QX , U.K
| | - Tejal Desai
- Department of Bioengineering and Therapeutic Sciences , University of California, San Francisco , San Francisco , California 94158 , United States
| | - Cécile A Dreiss
- School of Cancer & Pharmaceutical Sciences , King's College London , 150 Stamford Street , London SE1 9NH , U.K
| | - Robert D Barker
- School of Physical Sciences , University of Kent , Canterbury , Kent CT2 7NH , U.K
| | - Mark A Green
- Department of Physics , King's College London , Strand Campus , London WC2R 2LS , U.K
| | - Lea Ann Dailey
- Institut für Pharmazeutische Technologie und Biopharmazie , Martin-Luther-Universität Halle-Wittenberg , Halle 06120 , Germany
| | - Richard D Harvey
- Institut für Pharmazeutische Technologie und Biopharmazie , Martin-Luther-Universität Halle-Wittenberg , Halle 06120 , Germany
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19
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Harvey RD, Witt PR. Functional Properties of Brewers' Liquid Adjuncts. Journal of the American Society of Brewing Chemists 2018. [DOI: 10.1094/asbcj-41-0063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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20
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Harper RA, Saleh MM, Carpenter G, Abbate V, Proctor G, Harvey RD, Gambogi RJ, Geonnotti A, Hider R, Jones SA. Soft, adhesive (+) alpha tocopherol phosphate planar bilayers that control oral biofilm growth through a substantive antimicrobial effect. Nanomedicine 2018; 14:2307-2316. [PMID: 29410321 DOI: 10.1016/j.nano.2017.12.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 11/05/2017] [Accepted: 12/27/2017] [Indexed: 10/18/2022]
Abstract
'Soft' nanomaterials have the potential to produce substantive antibiofilm effects. The aim of this study was to understand the oral antimicrobial activity of soft nanomaterials generated from alpha-tocopherol (α-T) and alpha-tocopherol phosphate (α-TP). (+) α-TP formed planar bilayer islands (175 ± 21 nm, -14.9 ± 3.5 mV) in a Trizma® buffer, whereas (+) α-T formed spherical liposomes (563 ± 1 nm, -10.5 ± 0.2 mV). The (+) α-TP bilayers displayed superior Streptococcus oralis biofilm growth retardation, a more substantive action, generated a superior adsorption to hydroxyapatite and showed an enhanced inhibition of multi-species bacterial saliva biofilm growth (38 ± 7μm vs 58 ± 18 μm, P ˂ 0.05) compared to (+) α-T. Atomic force microscopy data indicated that the ability of the 'soft' α-TP nanomaterials to transition into planar bilayer structures upon contact with interfaces facilitated their adhesive properties and substantive antimicrobial effects.
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Affiliation(s)
- Robert A Harper
- King's College London, Institute of Pharmaceutical Science, Franklin-Wilkins Building, London, UK
| | - Mais M Saleh
- King's College London, Institute of Pharmaceutical Science, Franklin-Wilkins Building, London, UK
| | - Guy Carpenter
- King's College London, Dental institute, Division of Mucosal & Salivary Biology, Tower Wing, Great Maze Pond, London, UK
| | - Vincenzo Abbate
- King's College London, Institute of Pharmaceutical Science, Franklin-Wilkins Building, London, UK
| | - Gordon Proctor
- King's College London, Dental institute, Division of Mucosal & Salivary Biology, Tower Wing, Great Maze Pond, London, UK
| | - Richard D Harvey
- Martin-Luther-Universität Halle-Wittenberg, Institute of Pharmacy, Halle (Saale), Germany
| | - Robert J Gambogi
- Johnson and Johnson, Consumer & Personal Products Worldwide Division of Johnson & Johnson Consumer Companies, Inc, Skillman, NJ, USA
| | - Anthony Geonnotti
- Johnson and Johnson, Consumer & Personal Products Worldwide Division of Johnson & Johnson Consumer Companies, Inc, Skillman, NJ, USA
| | - Robert Hider
- King's College London, Institute of Pharmaceutical Science, Franklin-Wilkins Building, London, UK
| | - Stuart A Jones
- King's College London, Institute of Pharmaceutical Science, Franklin-Wilkins Building, London, UK.
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21
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Papadopoulos KP, El-Rayes BF, Tolcher AW, Patnaik A, Rasco DW, Harvey RD, LoRusso PM, Sachdev JC, Abbadessa G, Savage RE, Hall T, Schwartz B, Wang Y, Kazakin J, Shaib WL. A Phase 1 study of ARQ 087, an oral pan-FGFR inhibitor in patients with advanced solid tumours. Br J Cancer 2017; 117:1592-1599. [PMID: 28972963 PMCID: PMC5729432 DOI: 10.1038/bjc.2017.330] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [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: 05/08/2017] [Revised: 08/22/2017] [Accepted: 08/29/2017] [Indexed: 12/15/2022] Open
Abstract
Background: ARQ 087 is an orally administered pan-FGFR inhibitor with multi-kinase activity. This Phase 1 study evaluated safety, pharmacokinetics, and pharmacodynamics of ARQ 087 and defined the recommended Phase 2 dose (RP2D). Methods: Patients with advanced solid tumours received ARQ 087 administered initially at 25 mg every other day and dose-escalated from 25 to 425 mg daily (QD) continuous dosing. FGF19, 21, 23, and serum phosphate were assessed as potential biomarkers of target engagement. Results: 80 patients were enrolled, 61 in dose-escalation/food-effect cohorts and 19 with pre-defined tumour types in the expansion cohort. The most common ARQ 087-related adverse events were fatigue (49%), nausea (46%), aspartate aminotransferase (AST) increase (30%), and diarrhoea (23%). Four patients (5%) experienced grade 1 treatment-related hyperphosphataemia. Dose-limiting toxicity was reversible grade 3 AST increase. The RP2D was 300 mg QD. Pharmacokinetics were linear and dose-proportional from 25 to 325 mg QD, and were unaffected by food. Statistically significant changes (P-value<0.05) suggest phosphate and FGF19 levels as markers of target engagement. In 18 evaluable patients with FGFR genetic alterations, 3 confirmed partial responses (two intrahepatic cholangiocarcinomas (iCCA) with FGFR2 fusions and one urothelial cancer with FGFR2 and FGF19 amplification) and two durable stable disease at ⩾16 weeks with tumour reduction (FGFR2 fusion-positive iCCA and adrenocortical carcinoma with FGFR1 amplification) were observed. Conclusions: ARQ 087 had manageable toxicity at the RP2D of 300 mg QD, showed pharmacodynamics effects, and achieved objective responses, notably in patients with FGFR2 genetic alterations.
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Affiliation(s)
- K P Papadopoulos
- South Texas Accelerated Research Therapeutics, 4383 Medical Drive, San Antonio, TX 78229, USA
| | - B F El-Rayes
- Winship Cancer Institute of Emory University, 1365-C Clifton Road NE, Atlanta, GA 30322, USA
| | - A W Tolcher
- South Texas Accelerated Research Therapeutics, 4383 Medical Drive, San Antonio, TX 78229, USA
| | - A Patnaik
- South Texas Accelerated Research Therapeutics, 4383 Medical Drive, San Antonio, TX 78229, USA
| | - D W Rasco
- South Texas Accelerated Research Therapeutics, 4383 Medical Drive, San Antonio, TX 78229, USA
| | - R D Harvey
- Winship Cancer Institute of Emory University, 1365-C Clifton Road NE, Atlanta, GA 30322, USA
| | - P M LoRusso
- Karmanos Cancer Institute, 4206-4th Floor HWCRC, 4100 John R, Detroit, MI 48201, USA
| | - J C Sachdev
- Virginia G. Piper Cancer Center, Scottsdale Healthcare, 10460N 92nd Street, Scottsdale, AZ 85258, USA
| | - G Abbadessa
- ArQule, Inc. One Wall Street, Burlington, MA 01803, USA
| | - R E Savage
- ArQule, Inc. One Wall Street, Burlington, MA 01803, USA
| | - T Hall
- ArQule, Inc. One Wall Street, Burlington, MA 01803, USA
| | - B Schwartz
- ArQule, Inc. One Wall Street, Burlington, MA 01803, USA
| | - Y Wang
- ArQule, Inc. One Wall Street, Burlington, MA 01803, USA
| | - J Kazakin
- ArQule, Inc. One Wall Street, Burlington, MA 01803, USA
| | - W L Shaib
- Winship Cancer Institute of Emory University, 1365-C Clifton Road NE, Atlanta, GA 30322, USA
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Rehal RP, Marbach H, Hubbard AT, Sacranie AA, Sebastiani F, Fragneto G, Harvey RD. The influence of mild acidity on lysyl-phosphatidylglycerol biosynthesis and lipid membrane physico-chemical properties in methicillin-resistant Staphylococcus aureus. Chem Phys Lipids 2017. [DOI: 10.1016/j.chemphyslip.2017.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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23
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Wu B, Lewis LD, Harvey RD, Rasmussen E, Gamelin E, Sun YN, Friberg G, Koyner JL, Dowlati A, Maitland ML. A Pharmacokinetic and Safety Study of Trebananib, an Fc-Fusion Peptibody, in Patients With Advanced Solid Tumors and Varying Degrees of Renal Dysfunction. Clin Pharmacol Ther 2017; 102:313-320. [PMID: 28074547 DOI: 10.1002/cpt.617] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/12/2016] [Accepted: 01/03/2017] [Indexed: 01/09/2023]
Abstract
Clearance of trebananib (AMG 386), a 64-kD antiangiogenic peptibody, has been associated with estimated glomerular filtration rate (eGFR). We prospectively evaluated trebananib pharmacokinetics and safety/tolerability in advanced solid tumor patients with varying degrees of renal function. Patients were assigned to normal renal function, mild, moderate, or severe renal dysfunction cohorts based on eGFR, received trebananib 15 mg/kg i.v. weekly, and underwent week 1 and week 5 pharmacokinetic and weekly safety assessments. For 28 patients, trebananib clearance decreased from normal renal function (1.52 mL/hr/kg), to mild (1.20 mL/hr/kg), moderate (0.79 mL/hr/kg), and severe (0.53 mL/hr/kg) renal dysfunction (P ≤ 0.001). Treatment-related adverse events showed no association with clearance. Trebananib clearance was proportional to eGFR and unrelated to pretreatment protein excretion. These data confirm a role for renal clearance of a recombinant peptibody with molecular weight <69 kD and support a longer dosing interval for patients with severe renal dysfunction.
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Affiliation(s)
- B Wu
- Amgen Inc, Thousand Oaks, California, USA
| | - L D Lewis
- Department of Medicine, Geisel School of Medicine at Dartmouth and Norris Cotton Cancer Center at Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire, USA
| | - R D Harvey
- Emory University, Winship Cancer Institute, Atlanta, Georgia, USA
| | | | - E Gamelin
- Amgen Inc, Thousand Oaks, California, USA
| | - Y-N Sun
- Amgen Inc, Thousand Oaks, California, USA
| | - G Friberg
- Amgen Inc, Thousand Oaks, California, USA
| | - J L Koyner
- University of Chicago Medicine, Chicago, Illinois, USA
| | - A Dowlati
- Case Western Reserve University and University Hospitals Seidman Cancer Center, Cleveland, Ohio, USA
| | - M L Maitland
- University of Chicago Medicine, Chicago, Illinois, USA.,Inova Schar Cancer Institute and Center for Personalized Health, Falls Church, Virginia, USA
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24
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Hubbard ATM, Barker R, Rehal R, Vandera KKA, Harvey RD, Coates ARM. Mechanism of Action of a Membrane-Active Quinoline-Based Antimicrobial on Natural and Model Bacterial Membranes. Biochemistry 2017; 56:1163-1174. [PMID: 28156093 DOI: 10.1021/acs.biochem.6b01135] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [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
HT61 is a quinoline-derived antimicrobial, which exhibits bactericidal potency against both multiplying and quiescent methicillin resistant and sensitive Staphylococcus aureus, and has been proposed as an adjunct for other antimicrobials to extend their usefulness in the face of increasing antimicrobial resistance. In this study, we have examined HT61's effect on the permeability of S. aureus membranes and whether this putative activity can be attributed to an interaction with lipid bilayers. Using membrane potential and ATP release assays, we have shown that HT61 disrupts the membrane enough to result in depolarization of the membrane and release of intercellular constituents at concentrations above and below the minimum inhibitory concentration of the drug. Utilizing both monolayer subphase injection and neutron reflectometry, we have shown that increasing the anionic lipid content of the membrane leads to a more marked effect of the drug. In bilayers containing 25 mol % phosphatidylglycerol, neutron reflectometry data suggest that exposure to HT61 increases the level of solvent in the hydrophobic region of the membrane, which is indicative of gross structural damage. Increasing the proportion of PG elicits a concomitant level of membrane damage, resulting in almost total destruction when 75 mol % phosphatidylglycerol is present. We therefore propose that HT61's primary action is directed toward the cytoplasmic membrane of Gram-positive bacteria.
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Affiliation(s)
- Alasdair T M Hubbard
- Medical Microbiology, Institute for Infection and Immunity, St George's, University of London , Cranmer Terrace, London SW17 ORE, U.K
| | - Robert Barker
- Institut Laue Langevin , 71 avenue des Martyrs, 38042 Grenoble, France
| | - Reg Rehal
- Institute of Pharmaceutical Science, King's College London , Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Kalliopi-Kelli A Vandera
- Institute of Pharmaceutical Science, King's College London , Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Richard D Harvey
- Institute of Pharmaceutical Science, King's College London , Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - Anthony R M Coates
- Medical Microbiology, Institute for Infection and Immunity, St George's, University of London , Cranmer Terrace, London SW17 ORE, U.K
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Abstract
Two studies were conducted to develop and then validate a scale to measure the construct of Colorism. While colorism is a long discussed phenomena within the Black community in the United States, there have been virtually no attempts to measure the degree to which individuals embrace it. The In-Group Colorism Scale (ICS) was developed to assess the degree to which skin tone variation is important across five essential domains: Self-Concept, Affiliation, Attraction, Impression Formation, and Upward Mobility. The scale was empirically tested and then replicated using two distinct national samples of Black Americans (total sample of 783 participants). The ICS proved to have both good reliability and good structural validity. Moreover, the ICS proved to be significantly related to other important constructs such as parental socialization, skin tone, self-esteem, stereotypes, racial identity, and socioeconomic status. The implications of the ICS for both research and practical applications are discussed.
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Abstract
Although performance appraisal research has been ongoing for more than 50 years, the focus has largely been on the rater and the rating instruments. This study seeks to answer a more recent call by researchers to focus on contextual variables surrounding the performance appraisal process by analyzing two such variables: appraisal purpose and rater accountability. Results indicate that holding raters accountable for the accuracy of their ratings, especially when ratings are for administrative purposes, may be an effective strategy for reducing leniency error
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Ahmad Khanbeigi R, Abelha TF, Woods A, Rastoin O, Harvey RD, Jones MC, Forbes B, Green MA, Collins H, Dailey LA. Surface chemistry of photoluminescent F8BT conjugated polymer nanoparticles determines protein corona formation and internalization by phagocytic cells. Biomacromolecules 2015; 16:733-42. [PMID: 25590257 DOI: 10.1021/bm501649y] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Conjugated polymer nanoparticles are being developed for a variety of diagnostic and theranostic applications. The conjugated polymer, F8BT, a polyfluorene derivative, was used as a model system to examine the biological behavior of conjugated polymer nanoparticle formulations stabilized with ionic (sodium dodecyl sulfate; F8BT-SDS; ∼207 nm; -31 mV) and nonionic (pegylated 12-hydroxystearate; F8BT-PEG; ∼175 nm; -5 mV) surfactants, and compared with polystyrene nanoparticles of a similar size (PS200; ∼217 nm; -40 mV). F8BT nanoparticles were as hydrophobic as PS200 (hydrophobic interaction chromatography index value: 0.96) and showed evidence of protein corona formation after incubation with serum-containing medium; however, unlike polystyrene, F8BT nanoparticles did not enrich specific proteins onto the nanoparticle surface. J774A.1 macrophage cells internalized approximately ∼20% and ∼60% of the F8BT-SDS and PS200 delivered dose (calculated by the ISDD model) in serum-supplemented and serum-free conditions, respectively, while cell association of F8BT-PEG was minimal (<5% of the delivered dose). F8BT-PEG, however, was more cytotoxic (IC50 4.5 μg cm(-2)) than F8BT-SDS or PS200. The study results highlight that F8BT surface chemistry influences the composition of the protein corona, while the properties of the conjugated polymer nanoparticle surfactant stabilizer used determine particle internalization and biocompatibility profile.
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Affiliation(s)
- Raha Ahmad Khanbeigi
- Institute of Pharmaceutical Science, Franklin-Wilkins Building, King's College London , 150 Stamford Street, London SE1 9NH, U.K
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Bello G, Eriksson J, Terry A, Edwards K, Lawrence MJ, Barlow D, Harvey RD. Characterization of the aggregates formed by various bacterial lipopolysaccharides in solution and upon interaction with antimicrobial peptides. Langmuir 2015; 31:741-751. [PMID: 25514503 DOI: 10.1021/la503267k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The biophysical analysis of the aggregates formed by different chemotypes of bacterial lipopolysaccharides (LPS) before and after challenge by two different antiendotoxic antimicrobial peptides (LL37 and bovine lactoferricin) was performed in order to determine their effect on the morphology of LPS aggregates. Small-angle neutron scattering (SANS) and cryogenic transmission electron microscopy (cryoTEM) were used to examine the structures formed by both smooth and rough LPS chemotypes and the effect of the peptides, by visualization of the aggregates and analysis of the scattering data by means of both mathematical approximations and defined models. The data showed that the structure of LPS determines the morphology of the aggregates and influences the binding activity of both peptides. The morphologies of the worm-like micellar aggregates formed by the smooth LPS were relatively unaltered by the presence of the peptides due to their pre-existing high degree of positive curvature being little affected by their association with either peptide. On the other hand, the aggregates formed by the rough LPS chemotypes showed marked morphological changes from lamellar structures to ordered micellar networks, induced by the increase in positive curvature engendered upon association with the peptides. The combined use of cryoTEM and SANS proved to be a very useful tool for studying the aggregation properties of LPS in solution at biologically relevant concentrations.
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Affiliation(s)
- Gianluca Bello
- Institute of Pharmaceutical Science, King's College London , London, U.K
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29
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Tran DQ, Harvey RD, Meeks SL, Chapman R, Kempton CL. Use of factor VIII after inhibitor clearance in patients with moderate haemophilia A: a case series. Haemophilia 2014; 20:e344-6. [PMID: 24750497 DOI: 10.1111/hae.12452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/24/2014] [Indexed: 11/29/2022]
Affiliation(s)
- D Q Tran
- Department of Hematology and Medical Oncology, Emory University, School of Medicine, Atlanta, GA, USA
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Abstract
Therapeutic antibodies that block the programmed cell death protein-1 (PD-1) immune checkpoint pathway prevent T-cell downregulation and promote immune responses against cancer. Several PD-1 pathway inhibitors have shown robust activity in initial trials. This article reviews the preclinical evidence, rationale, and clinical pharmacology of blockade of PD-1 or its ligands as therapy for lung cancer and provides an overview of agents in development, clinical evidence to date, and implications for clinical application.
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Affiliation(s)
- R D Harvey
- Department of Hematology and Medical Oncology, Winship Cancer Institute of Emory University, Atlanta, Georgia, USA
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McCall AR, Harvey RD. Predictors of performance on the National Board of Chiropractic Examiners Parts I and II. J Chiropr Educ 2014; 28:9-15. [PMID: 24611459 PMCID: PMC3967654 DOI: 10.7899/jce-13-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Objective : The purpose of this study was to examine predictors for success on Parts I and II of the National Board of Chiropractic Examiners (NBCE) written examinations. Methods : Two validity studies were conducted to examine the criterion validity of Logan College assessments for Part I and II NBCE scores. Both studies consisted of a longitudinal design to examine the validity of entrance grade point average (GPA), in-program chiropractic course content GPA, and an institutional practice exam on Parts I and II of the NBCE. Results : Analyses revealed that Part I GPA and practice exam scores combined accounted for 72% of the variance within Part I NBCE scores. Furthermore, every subtest of the Part I NBCE could be reliably predicted by course performance. In the 2nd study, Part I GPA, Part I NBCE score, and Part II GPA accounted for 75% of the variance within Part II NBCE scores. Conclusions : Internal training and educational assessments (eg, course grades and practice exams) proved to be strong determinants of NBCE performance above and beyond initial levels of preparedness, thus validating the impact of the chiropractic curriculum on NBCE test achievement.
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Harvey RD, Ara N, Heenan RK, Barlow DJ, Quinn PJ, Lawrence MJ. Stabilization of distearoylphosphatidylcholine lamellar phases in propylene glycol using cholesterol. Mol Pharm 2013; 10:4408-17. [PMID: 24171434 DOI: 10.1021/mp400140u] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phospholipid vesicles (liposomes) formed in pharmaceutically acceptable nonaqueous polar solvents such as propylene glycol are of interest in drug delivery because of their ability to improve the bioavailability of drugs with poor aqueous solubility. We have demonstrated a stabilizing effect of cholesterol on lamellar phases formed by dispersion of distearoylphosphatidylcholine (DSPC) in water/propylene glycol (PG) solutions with glycol concentrations ranging from 0 to 100%. The stability of the dispersions was assessed by determining the effect of propylene glycol concentration on structural parameters of the lamellar phases using a complementary combination of X-ray and neutron scattering techniques at 25 °C and in the case of X-ray scattering at 65 °C. Significantly, although stable lamellar phases (and liposomes) were formed in all PG solutions at 25 °C, the association of the glycol with the liposomes' lamellar structures led to the formation of interdigitated phases, which were not thermostable at 65 °C. With the addition of equimolar quantities of cholesterol to the dispersions of DSPC, stable lamellar dispersions (and indeed liposomes) were formed in all propylene glycol solutions at 25 °C, with the significant lateral phase separation of the bilayer components only detectable in propylene glycol concentrations above 60% (w/w). We propose that the stability of lamellar phases of the cholesterol-containing liposomes formed in propylene glycol concentrations of up to 60% (w/w) represent potentially very valuable drug delivery vehicles for a variety of routes of administration.
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Affiliation(s)
- Richard D Harvey
- Pharmaceutical Biophysics Group, Institute of Pharmaceutical Science, King's College London , 150 Stamford Street, London SE1 9NH, United Kingdom
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33
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Harvey RD, Owonikoko TK, Lewis CM, Akintayo A, Chen Z, Tighiouart M, Ramalingam SS, Fanucchi MP, Nadella P, Rogatko A, Shin DM, El-Rayes B, Khuri FR, Kauh JS. A phase 1 Bayesian dose selection study of bortezomib and sunitinib in patients with refractory solid tumor malignancies. Br J Cancer 2013; 108:762-5. [PMID: 23322195 PMCID: PMC3590658 DOI: 10.1038/bjc.2012.604] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND This phase 1 trial utilising a Bayesian continual reassessment method evaluated bortezomib and sunitinib to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLT), and recommended doses of the combination. METHODS Patients with advanced solid organ malignancies were enrolled and received bortezomib weekly with sunitinib daily for 4 weeks, every 6 weeks. Initial doses were sunitinib 25 mg and bortezomib 1 mg m(-2). Cohort size and dose level estimation was performed utilising the Escalation with Overdose Control (EWOC) adaptive method. Seven dose levels were evaluated; initially, sunitinib was increased to a goal dose of 50 mg with fixed bortezomib, then bortezomib was increased. Efficacy assessment occurred after each cycle using RECIST criteria. RESULTS Thirty patients were evaluable. During sunitinib escalation, DLTs of grade 4 thrombocytopenia (14%) and neutropenia (6%) at sunitinib 50 mg and bortezomib 1.3 mg m(-2) were seen. Subsequent experience showed tolerability and activity for sunitinib 37.5 mg and bortezomib 1.9 mg m(-2). Common grade 3/4 toxicities were neutropenia, thrombocytopenia, hypertension, and diarrhoea. The recommended doses for further study are bortezomib 1.9 mg m(-2) and sunitinib 37.5 mg. Four partial responses were seen. Stable disease >6 months was noted in an additional six patients. CONCLUSION Bortezomib and sunitinib are well tolerated and have anticancer activity, particularly in thyroid cancer. A phase 2 study of this combination in thyroid cancer patients is planned.
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Affiliation(s)
- R D Harvey
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, USA.
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Bolton LR, Harvey RD, Grawitch MJ, Barber LK. Counterproductive work behaviours in response to emotional exhaustion: a moderated mediational approach. Stress Health 2012; 28:222-33. [PMID: 22281803 DOI: 10.1002/smi.1425] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 08/05/2011] [Accepted: 08/10/2011] [Indexed: 11/06/2022]
Abstract
Drawing from the conservation of resources framework and self-control principles, we proposed a moderated mediational model through which emotional exhaustion may be linked to counterproductive work behaviours (CWBs). Analyses conducted with 175 Midwestern government workers revealed that both depersonalization (i.e. detachment from one's work, customers or co-workers) and organizational disidentification (i.e. cognitive opposition to an organization) were viable predictors of deviancy. Further, depersonalization and disidentification mediated the relationship between emotional exhaustion and CWBs, although disidentification drove these findings. Lastly, trait self-control moderated most variations of this relationship, in that this mediational model only applied to individuals with low and moderate self-control but not high self-control. Consistent with the conservation of resources framework, this study suggests that in a state of depleted emotional resources, heightened depersonalization and disidentification together provide the necessary levels of psychological/emotional withdrawal and justification for CWBs to emerge.
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Goatman KA, Philip S, Fleming AD, Harvey RD, Swa KK, Styles C, Black M, Sell G, Lee N, Sharp PF, Olson JA. External quality assurance for image grading in the Scottish Diabetic Retinopathy Screening Programme. Diabet Med 2012; 29:776-83. [PMID: 22023553 DOI: 10.1111/j.1464-5491.2011.03504.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [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: 11/29/2022]
Abstract
AIMS To develop and evaluate an image grading external quality assurance system for the Scottish Diabetic Retinopathy Screening Programme. METHOD A web-based image grading system was developed which closely matches the current Scottish national screening software. Two rounds of external quality assurance were run in autumn 2008 and spring 2010, each time using the same 100 images. Graders were compared with a consensus standard derived from the top-level graders' results. After the first round, the centre lead clinicians and top-level graders reviewed the results and drew up guidance notes for the second round. RESULTS Grader sensitivities ranged from 60.0 to 100% (median 92.5%) in 2008, and from 62.5 to 100% (median 92.5%) in 2010. Specificities ranged from 34.0 to 98.0% (median 86%) in 2008, and 54.0 to 100% (median 88%) in 2010. There was no difference in sensitivity between grader levels, but first-level graders had a significantly lower specificity than level-two and level-three graders. In 2008, one centre had a lower sensitivity but higher specificity than the majority of centres. Following the feedback from the first round, overall agreement improved in 2010 and there were no longer any significant differences between centres. CONCLUSIONS A useful educational tool has been developed for image grading external quality assurance.
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Affiliation(s)
- K A Goatman
- School of Medicine and Dentistry, University of Aberdeen, Foresterhill, Aberdeen, UK.
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Junkes C, Harvey RD, Bruce KD, Dölling R, Bagheri M, Dathe M. Cyclic antimicrobial R-, W-rich peptides: the role of peptide structure and E. coli outer and inner membranes in activity and the mode of action. Eur Biophys J 2011; 40:515-28. [PMID: 21286704 DOI: 10.1007/s00249-011-0671-x] [Citation(s) in RCA: 38] [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] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 12/07/2010] [Accepted: 01/03/2011] [Indexed: 11/25/2022]
Abstract
This study compares the effect of cyclic R-, W-rich peptides with variations in amino acid sequences and sizes from 5 to 12 residues upon Gram negative and Gram positive bacteria as well as outer membrane-deficient and LPS mutant Escherichia coli (E. coli) strains to analyze the structural determinants of peptide activity. Cyclo-RRRWFW (c-WFW) was the most active and E. coli-selective sequence and bactericidal at the minimal inhibitory concentration (MIC). Removal of the outer membrane distinctly reduced peptide activity and the complete smooth LPS was required for maximal activity. c-WFW efficiently permeabilised the outer membrane of E. coli and promoted outer membrane substrate transport. Isothermal titration calorimetric studies with lipid A-, rough-LPS (r-LPS)- and smooth-LPS (s-LPS)-doped POPC liposomes demonstrated the decisive role of O-antigen and outer core polysaccharides for peptide binding and partitioning. Peptide activity against the inner E. coli membrane (IM) was very low. Even at a peptide to lipid ratio of 8/1, c-WFW was not able to permeabilise a phosphatidylglycerol/phosphatidylethanolamine (POPG/POPE) bilayer. Low influx of propidium iodide (PI) into bacteria confirmed a low permeabilising ability of c-WFW against PE-rich membranes at the MIC. Whilst the peptide effect upon eukaryotic cells correlated with the amphipathicity and permeabilisation of neutral phosphatidylcholine bilayers, suggesting a membrane disturbing mode of action, membrane permeabilisation does not seem to be the dominating antimicrobial mechanism of c-WFW. Peptide interactions with the LPS sugar moieties certainly modulate the transport across the outer membrane and are the basis of the E. coli selectivity of this type of peptides.
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Affiliation(s)
- Christof Junkes
- Leibniz Institute of Molecular Pharmacology (FMP), Robert-Roessle-Str. 10, 13125 Berlin, Germany
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Harvey RD, Afful SE. Racial Typicality, Racial Identity, and Health Behaviors: A Case for Culturally Sensitive Health Interventions. Journal of Black Psychology 2010. [DOI: 10.1177/0095798410376244] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Culturally sensitive health interventions have proven to be vitally important for the elimination of the health disparities that Black Americans face. The purpose of this study was to illuminate the role and importance of health behavior racial typicality and racial identification in how Black Americans view and engage in health behaviors. Black Americans completed racial identity measures and rated a variety of both health-promoting and health-compromising behaviors on whether they were more typical of Blacks or Whites (i.e., racial typicality), personal importance, and frequency of engagement. Results indicated the extent to which health behaviors were viewed as relatively more descriptive of Blacks (rather than Whites) was associated with higher perceived importance and greater frequency of engagement, particularly among those reporting higher levels of nationalist racial identification. Finally, health behavior importance mediated the relationship between racial typicality of the behavior and engagement in the behavior. The results of the study are discussed in terms of their implications for providing empirical support for the necessity of culturally tailored interventions in eliminating Black American health disparities.
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Harvey RD, Nettles J, Wang B, Sun SY, Lonial S. Commentary on Perrone et al.: 'vitamin C: not for breakfast anymore...if you have myeloma'. Leukemia 2009; 23:1939-40. [PMID: 19904281 DOI: 10.1038/leu.2009.128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- R D Harvey
- Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
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Hollinshead CM, Harvey RD, Barlow DJ, Webster JRP, Hughes AV, Weston A, Lawrence MJ. Effects of surface pressure on the structure of distearoylphosphatidylcholine monolayers formed at the air/water interface. Langmuir 2009; 25:4070-4077. [PMID: 19714892 DOI: 10.1021/la8028319] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The structure of the monolayer formed at an air/water interface by the phospholipid distearoylphosphatidylcholine (DSPC) has been determined as a function of the monolayer surface pressure (pi) using Brewster angle microscopy and neutron reflectivity. The microscopy studies demonstrate that the DSPC molecules form an extremely homogeneous monolayer on the water surface with no evidence of any domain formation. The neutron reflectivity measurements provide information on the thickness of the DSPC alkyl chains, head groups, and associated solvent distributions, along with the separations between these distributions and the interfacial area per molecule. Partial structure factor analyses of the reflectivity data show that the area occupied by each DSPC molecule decreases from 49 A2 at pi = 20 mN/m to 44 A2 at pi = 50 mN/m. There are concomitant increases in the widths of the lipids' alkyl chains and headgroup distributions (modeled as Gaussians), with the former rising from 18 A (at pi = 20 mN/m) to 20 A (at pi = 50 mN/m) and the latter rising from 14 A (at pi = 20 mN/m) to 18 A (at pi = 50 mN/m). The compression of the monolayer is also shown to give rise to an increased surface roughness, the principal component of which is found to be the thermal roughness caused by capillary waves. At all surface pressures studied (covering the range from 20 to 50 mN/m), the alkyl chains and head groups of the DSPC are found to have roughly the same orientations, with the alkyl chains tilted with respect to the surface normal by about 34 degrees and the head groups lying parallel to the interface normal, projecting vertically down into the aqueous subphase. Given the various trends noted on how the structure of the DSPC monolayer changes as a function of pi, we extrapolate to consider the structure of the monolayer immediately before its collapse.
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Affiliation(s)
- Clare M Hollinshead
- Pharmaceutical Science Division, King's College London, The Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
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Harvey RD, Lawrence MJ, Bui TT. Probing the steric barrier of nonionic surfactant vesicles with melittin. Biochimica et Biophysica Acta (BBA) - Biomembranes 2008; 1778:2081-90. [DOI: 10.1016/j.bbamem.2008.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 03/24/2008] [Accepted: 04/07/2008] [Indexed: 10/22/2022]
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Barlow DJ, Hollinshead CM, Harvey RD, Kudsiova L, Lawrence MJ. Memory effects of monolayers and vesicles formed by the non-ionic surfactant, 2C18E12. J Colloid Interface Sci 2007; 316:741-50. [PMID: 17825312 DOI: 10.1016/j.jcis.2007.08.014] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Revised: 08/02/2007] [Accepted: 08/06/2007] [Indexed: 11/25/2022]
Abstract
The behaviour of monolayers and bilayers formed by the dialkyl chain non-ionic surfactant, 1,2-di-O-octadecyl-rac-glycerol-3-omega-methoxydodecaethylene glycol (2C(18)E(12)) in water at 297 K has been investigated. Using a surface film balance (or Langmuir trough) the compression-expansion cycle of the 2C(18)E(12) monolayer was found to be reversible when compressed to surface pressures (pi) less than 42 mN m(-1). Compression of 2C(18)E(12) monolayer to pi greater than 42 mN m(-1) above this resulted in a considerable hysteresis upon expansion with the pi remaining high relative to that obtained upon compression, suggesting a time/pressure dependent re-arrangement of 2C(18)E(12) molecules in the film. Morphology of the 2C(18)E(12) monolayer, investigated using Brewster angle microscopy, was also found to depend upon monolayer history. Bright, randomly dispersed domains of 2C(18)E(12) of approximately 5 mum in size were observed during compression of the monolayer to pi less than 42 mN m(-1). At pi of 42 mN m(-1) and above, the surfactant film appeared to be almost completely 'solid-like.' Regardless of the extent of compression of the monolayer film, expansion of the film caused formation of chains or 'necklaces' of individual surfactant domains, with the extent of chain formation dependent upon pressure of compression of the monolayer and the length of time held at that pressure. Irreversible effects on 2C(18)E(12) vesicle size were also seen upon temperature cycling the vesicles through their liquid-crystalline phase transition temperature with vesicles shrinking in size and not returning to their original size upon standing at 298 K for periods of more than 24 h. No comparable hysteresis, time, pressure or temperature effects were observed with the monolayer or vesicles formed by the corresponding phospholipid, disteaorylphosphatidylcholine, under identical conditions. The effects observed with 2C(18)E(12) are attributed to the ability of the polyoxyethylene head group to dehydrate and intrude into the hydrophobic chain region of the mono- and bilayers. These studies have important implications for the use of the vesicles formed by 2C(18)E(12) as drug delivery vehicles.
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Affiliation(s)
- D J Barlow
- Department of Pharmacy, Franklin Wilkins Building, King's College London, 150 Stamford Street, London SE1 9NH, UK
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Ma G, Barlow DJ, Hollinshead CM, Harvey RD, Webster JRP, Lawrence MJ. Effects of surface pressure on the structure of the monolayer formed at the air/water interface by a non-ionic surfactant. J Colloid Interface Sci 2007; 317:314-25. [PMID: 17931647 DOI: 10.1016/j.jcis.2007.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/29/2007] [Accepted: 09/03/2007] [Indexed: 10/22/2022]
Abstract
The monolayer formed at an air/water interface by the synthetic non-ionic surfactant, 1,2-di-O-octadecyl-rac-glyceryl-3-(omega-methoxydodecakis (ethylene glycol)) (2C18E12) has been characterized using Langmuir trough measurements, Brewster angle microscopy (BAM), and neutron reflectometry. The BAM and reflectometry studies were performed at four different surface pressures (pi) in the range 15-40 mN/m. The BAM studies (which give information on the in-plane organisation of the surfactant layer) demonstrate that the 2C18E12 molecules are arranged on the water surface to form distinct, approximately circular, 5 microm diameter domains. As the surface pressure is increased these domains retain their size and shape but are made progressively more close-packed, such that the monolayer is made more or less complete at pi=40 mN/m. The neutron reflectometry measurements were made to determine the structure of the interfacial surfactant layer at pi=15, 28, 34 and 40 mN/m, providing information on the thickness of the 2C18E12 alkyl chains', head groups' and associated solvent distributions (measured along the surface normal), along with the separations between these distributions, and the effective interfacial area per molecule. Partial structure factor analyses of the reflectivity data show that the effective interfacial area occupied decreases from 217 A2 per 2C18E12 molecule at pi=15 mN/m down to 102 A2 at pi=40 mN/m. There are concomitant increases in the widths of the surfactant's alkyl chains' and head groups' distributions (modelled as Gaussians), with the former rising from 12 A (at pi=15 mN/m) up to 19 A (at pi=40 mN/m) and the latter rising from 13 A (at pi=15 mN/m) up to 24 A (at pi=40 mN/m). The compression of the monolayer is also shown to give rise to an increased surface roughness, some of which is due to the thermal roughness caused by capillary waves, but with a significant contribution also coming from the intrinsic/structural disorder in the monolayer. At all surface pressures studied, the alkyl chains and head groups of the 2C18E12 are found to exhibit a significant overlap, and this increases with increasing pi. Given the various trends noted on how the structure of the 2C18E12 monolayer changes as a function of pi, we extrapolate to consider the structure of the monolayer at pi>40 mN/m (making comparison with its single chain (CnEm) counterparts) and then relate these findings to the observations recorded on the structure and solute entrapment efficiency of 2C18E12 vesicles.
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Affiliation(s)
- G Ma
- Pharmaceutical Sciences Division, King's College London, The Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
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Harvey RD, Barlow DJ, Drake AF, Kudsiova L, Lawrence MJ, Brain APR, Heenan RK. The effect of electrolyte on the encapsulation efficiency of vesicles formed by the nonionic surfactant, 2C18E12. J Colloid Interface Sci 2007; 315:648-61. [PMID: 17692324 DOI: 10.1016/j.jcis.2007.06.076] [Citation(s) in RCA: 17] [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] [Received: 04/10/2007] [Revised: 06/18/2007] [Accepted: 06/29/2007] [Indexed: 10/23/2022]
Abstract
Encapsulation efficiencies of vesicles formed by the nonionic surfactant 1,2-dioctadecyl-rac-glycerol-3-omega-methoxydodecylethylene glycol (abbreviated as 2C18E12) and its phospholipid counterpart, distearoylphosphatidylcholine (DSPC) at 298 K, were determined by the entrapment of the water-soluble dye, carboxyfluorescein (CF) to be 0.045+/-0.001 and 0.03+/-0.04 L mol(-1) for 2C18E12 vesicles prepared using low osmolarity (270 m Osm) Krebs-Henseleit (K-H) buffer and a modified 'high salt' (1600 m Osm) variant of K-H buffer, respectively, and 0.64+/-0.01 and 0.31+/-0.04 Lmol(-1) for DSPC vesicles prepared under the same conditions and in the same buffers. Freeze fracture electron microscopy studies confirmed the presence of vesicles when 2C18E12 and DSPC were dispersed in water and both buffer solutions. Small angle neutron scattering (SANS) studies, using D2O in place of H2O, showed that when 2C18E12 vesicles were prepared in the 'high salt' variant of K-H buffer as opposed to K-H buffer or water, a higher proportion of multilamellar vesicles (MLV) were formed. Furthermore when prepared in the 'high salt' variant of K-H buffer, the 2C18E12 bilayers were thinner, and when present in the form of MLV exhibited a smaller layer of water separating the bilayers. However, even in the absence of electrolyte, 2C18E12 formed surprisingly thin bilayers due to the penetration of the polyoxyethylene chains into the hydrophobic chain region of the bilayer. Due to the dehydrating effect of the high concentration of electrolyte present in the 'high salt' variant of K-H, the polyoxyethylene head groups penetrated further into the hydrophobic region of the bilayer making the bilayer even thinner. In the case of the DSPC vesicles, although the SANS study showed an increase in the relative proportion of multilamellar to unilamellar vesicles when samples were prepared in the 'high salt' variant of K-H buffer, no differences were observed in the thickness and the d-spacing of the vesicle bilayers. Variable temperature turbidity measurements of 2C18E12, and DSPC vesicles prepared in water indicated phase changes at 320+/-0.5 and 327+/-0.5 K, respectively, and were unchanged when the 'high salt' variant of K-H buffer was used as hydrating medium. Taken together, these results suggest that a low phase transition temperature was not the reason for the poor entrapment efficiency of 2C18E12 vesicles but rather the very 'thin' hydrophobic barrier formed by the penetration of the polyoxyethylene chains into the hydrophobic region of the bilayer.
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Affiliation(s)
- Richard D Harvey
- Pharmaceutical Sciences Division, King's College London, Franklin Wilkins Building, Waterloo Campus, London SE1 9NH, UK
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Harvey RD, Heenan RK, Barlow DJ, Lawrence MJ. The effect of electrolyte on the morphology of vesicles composed of the dialkyl polyoxyethylene ether surfactant 2C18E12. Chem Phys Lipids 2005; 133:27-36. [PMID: 15589224 DOI: 10.1016/j.chemphyslip.2004.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Revised: 07/20/2004] [Accepted: 08/23/2004] [Indexed: 11/28/2022]
Abstract
Small-angle neutron-scattering (SANS) studies were performed on vesicles composed of 1,2-di-O-octadecyl-rac-glyceryl-3-(omega-methoxydodecaethylene glycol), in deuterium oxide (D2O) solutions with various ionic strengths of LiCl, NaCl and NaI. Gross vesicle morphologies, examined using freeze-fracture electron microscopy, showed that NaCl promoted the formation of multilamellar vesicles. Model fitting of the SANS data showed changes in bilayer parameters such as thickness and repeat spacings, in response to the presence of ions in the bulk solution. 2C18E12 vesicles in D2O are shown to exist as predominantly unilamellar structures with a bilayer thickness of approximately 51 A. Vesicles in increasing concentrations of LiCl and NaCl exhibit decreased layer thickness and increased lamelarity. Little change was observed for vesicles formed in NaI solutions. We suggest that these changes result from intrusion of E12 headgroups into the alkyl chain region of the vesicle bilayers, in response to the increase in concentration of ions present and their charge density.
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Affiliation(s)
- Richard D Harvey
- Department of Pharmacy, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NN, UK
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Harvey RD, Heenan RK, Barlow DJ, Lawrence MJ. Effect of cholesterol and phospholipid on the behavior of dialkyl polyoxyethylene ether surfactant (2C18E12) monolayers and bilayers. Langmuir 2004; 20:9282-9290. [PMID: 15461519 DOI: 10.1021/la0400297] [Citation(s) in RCA: 5] [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] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Surface pressure-area isotherm, neutron specular reflection, and small-angle neutron scattering studies have been carried out to determine the effects of added cholesterol and distearoylphosphatidylcholine (DSPC), on the molecular structures of monolayers and vesicles containing the dialkyl polyoxyethylene ether surfactant, 1,2-di-O-octadecyl-rac-glyceryl-3-(alpha-dodecaethylene glycol) (2C18E12). Previous neutron reflectivity studies on 2C18E12 monolayers at the air/water interface have shown them to possess a thickness of approximately 24 angstoms and highly disordered structure with significant intermixing of the polymer headgroups and alkyl chains. SANS studies of 2C18E12 vesicles gave a bilayer thickness of approximately 51 angstroms. Addition of cholesterol to 2C18E12 monolayers (1:1 molar ratio), produced a marked condensing effect coupled with an increased the layer thickness of approximately 7 angstroms, and in vesicles, increased bilayer thickness by approximately 16 angstroms. Monolayers consisting of 2C18E12:DSPC:cholesterol (1:1:2 molar ratio), showed a layer thickness of approximately 31 angstroms, whereas in vesicles, three-component bilayer was found to be only approximately 9 angstroms thicker than those possessed by vesicles composed solely of 2C18E12. Mixing between the molecules in three-component monolayers was shown to be ideal through analysis of the neutron reflectivity data. These findings are discussed in relation to increased ordering and decreased headgroup/hydrophobe intermixing within both monolayers and vesicle bilayers containing 2C18E12. The inferred increase in molecular order within vesicles composed of 2C18E12 with additional cholesterol and phospholipid is used as a model for explaining theoretical differences in bilayer permeability.
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Affiliation(s)
- Richard D Harvey
- Department of Pharmacy, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NN, United Kingdom
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Belevych AE, Nulton-Persson A, Sims C, Harvey RD. Role of tyrosine kinase activity in alpha-adrenergic inhibition of the beta-adrenergically regulated L-type Ca(2+) current in guinea-pig ventricular myocytes. J Physiol 2001; 537:779-92. [PMID: 11744754 PMCID: PMC2278981 DOI: 10.1111/j.1469-7793.2001.00779.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. The purpose of this study was to investigate the hypothesis that tyrosine kinase activity contributes to alpha(1)-adrenergic inhibition of beta-adrenergic responses in cardiac myocytes. We addressed this question by studying the pharmacological regulation of the L-type Ca(2+) current in acutely isolated adult guinea-pig ventricular myocytes using the whole-cell patch-clamp technique. 2. The selective alpha(1)-adrenergic receptor agonist methoxamine had no effect on the basal L-type Ca(2+) current. Methoxamine also had no effect on cAMP-dependent stimulation of the Ca(2+) current mediated by H(2) histamine receptor activation. However, methoxamine did inhibit cAMP-dependent stimulation of the Ca(2+) current mediated by beta-adrenergic receptor activation. The ability of methoxamine to inhibit beta-adrenergic regulation of the Ca(2+) current was significantly antagonized by the tyrosine kinase inhibitors genistein and lavendustin A. 3. The inhibitory effect of methoxamine was also mimicked by the phosphotyrosine phosphatase inhibitor pervanadate (PVN). PVN had no effect on basal Ca(2+) current or Ca(2+) current stimulated by histamine, but it did inhibit Ca(2+) current stimulated by beta-adrenergic receptor activation. Furthermore, the ability of PVN to inhibit beta-adrenergic stimulation of the Ca(2+) current was antagonized by lavendustin A. 4. These results are consistent with the conclusion that in guinea-pig ventricular myocytes alpha-adrenergic inhibition of beta-adrenergic responses involves a tyrosine kinase-dependent signalling pathway. The fact that methoxamine and PVN antagonized cAMP-dependent responses mediated by beta-adrenergic, but not H(2) histamine, receptor activation suggests that the inhibitory effect of alpha-adrenergic stimulation and tyrosine kinase activity is at the level of the beta-adrenergic receptor.
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Affiliation(s)
- A E Belevych
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106, USA
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Abstract
Metastatic tumors to the brain are an increasing cause of morbidity and mortality in patients with systemic cancers. Many new therapies used to treat systemic cancers do not penetrate the central nervous system (CNS) and do not protect patients from the development of brain metastases. Surgery, radiosurgery, and radiation therapy are all used to treat brain metastases. It is in our opinion a mistake to use only one or two of these modalities to the exclusion of other(s). The role of systemic chemotherapy is still limited, due to both the issues of drug delivery caused by the blood brain barrier and to the relative resistance of many of these tumors to chemotherapy. Traditionally, brain metastases have been grouped together regardless of the origin of the tumor and have been treated with a single algorithm. As we encounter more patients for whom treatment of the brain metastases is an important determinant of survival, we must tailor our treatment strategies to individual tumor types. Also, we must recognize differences in each tumor's sensitivity to chemotherapy and radiotherapy and differences in their biology.
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Affiliation(s)
- M G Ewend
- Division of Neurosurgery, University of North Carolina at Chapel Hill, 148 Burnett-Womack Building, Campus Box 7060, Chapel Hill, NC 27599-7060, USA.
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Belevych AE, Sims C, Harvey RD. ACh-induced rebound stimulation of L-type Ca(2+) current in guinea-pig ventricular myocytes, mediated by Gbetagamma-dependent activation of adenylyl cyclase. J Physiol 2001; 536:677-92. [PMID: 11691864 PMCID: PMC2278900 DOI: 10.1111/j.1469-7793.2001.00677.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
1. The effects that muscarinic receptor stimulation have on the cAMP-dependent regulation of L-type Ca(2+) currents were studied in isolated guinea-pig ventricular myocytes using the whole-cell configuration of the patch-clamp technique. 2. The muscarinic agonist ACh inhibited the Ca(2+) current stimulated by the beta-adrenergic agonist isoprenaline (Iso), and washout of ACh revealed a stimulatory response that appeared as a transient rebound increase in the amplitude of the Ca(2+) current. The ACh-induced stimulatory effect was not observed in the absence of Iso. 3. ACh-induced rebound stimulation was also observed in the presence of H(2) histamine receptor activation and cholera toxin treatment, which like beta-adrenergic receptor activation enhance adenylyl cyclase (AC) activity in a stimulatory G protein (G(s))-dependent manner. ACh-induced rebound stimulation was not observed in the presence of forskolin, which enhances AC activity in a G(s)-independent manner. 4. Pertussis toxin (PTX) treatment blocked both the stimulatory and inhibitory effects of ACh. Intracellular dialysis with QEHA, a peptide that binds free G protein betagamma subunits, selectively antagonized the stimulatory effect, leaving an enhanced inhibitory effect. 5. Evidence for the expression of AC4, an isoform of AC that can be stimulated by Gbetagamma but only in the presence of Galpha(s), was obtained by Western blot analysis of guinea-pig ventricular myocyte membrane preparations. 6. These results suggest that muscarinic receptor stimulation facilitates as well as inhibits cAMP-dependent regulation of the Ca(2+) current and that the net response is a balance between these two actions. We suggest that the stimulatory effect is due to a direct activation of AC4 by the betagamma subunits of a PTX-sensitive G protein.
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Affiliation(s)
- A E Belevych
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106-4970, USA
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Abstract
In an attempt to define stigmatization from the perspective of stigmatized group members, the author focused on the development and validation of a stigmatization scale. The scale's content validity was established with the assistance of experts in the field. European American, African American, and Native American students from 5 different U.S. universities completed the Stigmatization Scale. The construct validity of the scale was suggested by its convergence with similar measures of social alienation and its divergence from measures of personal subjective well-being. The finding that both the African American and Native American students reported significantly higher stigmatization scores than did the European Americans indicated the scale's known-groups validity. African American students at a predominantly Black university reported lower stigmatization than did African American students at a predominantly White university, suggesting the scale's malleability to context.
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Affiliation(s)
- R D Harvey
- Department of Psychology, Saint Louis University, 221 N. Grand Blvd., St. Louis, MO 63103, USA.
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