1
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Cui L, Kudsiova L, Campbell F, Barlow DJ, Hailes HC, Tabor AB, Lawrence MJ. Understanding and optimising the transfection of lipopolyplexes formulated in saline: the effects of peptide and serum. Biomater Sci 2023; 11:3335-3353. [PMID: 36960608 DOI: 10.1039/d2bm01905a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
Lipopolyplexes (LPDs) are of considerable interest for use as gene delivery vehicles. Here LPDs have been prepared from cationic vesicles (composed of a 1 : 1 molar ratio of DOTMA with the neutral helper lipid, DOPE), singly branched cationic peptides and plasmid DNA. All peptides contained a linker sequence (cleaved by endosomal furin) attached to a targeting sequence selected to bind human airway epithelial cells and mediate gene delivery. The current study investigates the effects of novel Arg-containing cationic peptide sequences on the biophysical and transfection properties of LPDs. Mixed His/Arg cationic peptides were of particular interest, as these sequences have not been previously used in LPD formulations. Lengthening the number of cationic residues in a homopolymer from 6 to 12 in each branch reduced transfection using LPDs, most likely due to increased DNA compaction hindering the release of pDNA within the target cell. Furthermore, LPDs containing mixed Arg-containing peptides, particularly an alternating Arg/His sequence exhibited an increase in transfection, probably because of their optimal ability to complex and subsequently release pDNA. To confer stability in serum, LPDs were prepared in 0.12 M sodium chloride solution (as opposed to the more commonly used water) yielding multilamellar LPDs with very high levels of size reproducibility and DNA protection, especially when compared to the (unilamellar) LPDs formed in water. Significantly for the clinical applications of the LPDs, those prepared in the presence of sodium chloride retained high levels of transfection in the presence of media supplemented with fetal bovine serum. This work therefore represents a significant advance for the optimisation of LPD formulation for gene delivery, under physiologically relevant conditions, in vivo.
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Affiliation(s)
- Lili Cui
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, Waterloo Campus, London SE1 9NH, UK
| | - Laila Kudsiova
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, Waterloo Campus, London SE1 9NH, UK
| | - Frederick Campbell
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - David J Barlow
- Division of Pharmacy & Optometry, School of Health Sciences, University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PT, UK.
| | - Helen C Hailes
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Alethea B Tabor
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - M Jayne Lawrence
- Institute of Pharmaceutical Science, King's College London, Franklin-Wilkins Building, 150 Stamford Street, Waterloo Campus, London SE1 9NH, UK
- Division of Pharmacy & Optometry, School of Health Sciences, University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PT, UK.
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2
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Beddoes CM, Gooris GS, Barlow DJ, Lawrence MJ, Dalgliesh RM, Malfois M, Demé B, Bouwstra JA. The importance of ceramide headgroup for lipid localisation in skin lipid models. Biochim Biophys Acta Biomembr 2022; 1864:183886. [PMID: 35143742 DOI: 10.1016/j.bbamem.2022.183886] [Citation(s) in RCA: 2] [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] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/01/2022] [Accepted: 02/02/2022] [Indexed: 06/14/2023]
Abstract
The stratum corneum's lipid matrix is a critical for the skin's barrier function and is primarily composed of ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs). The lipids form a long periodicity phase (LPP), a unique trilayer unit cell structure. An enzyme driven pathway is implemented to synthesize these key lipids. If these enzymes are down- or upregulated as in inflammatory diseases, the final lipid composition is affected often altering the barrier function. In this study, we mimicked down regulation of enzymes involved in the synthesis of the sphingosine and CER amide bond. In a LPP lipid model, we substituted CER N-(tetracosanoyl)-sphingosine (CER NS) with either i) FFA C24 and free sphingosine, to simulate the loss of the CER amide bond, or ii) with FFA C24 and C18 to simulate the loss of the sphingosine headgroup. Our study shows the lipids in the LPP would not phase separate until at least 25% of the CER NS is substituted keeping the lateral packing and conformational ordering unaltered. Neutron diffraction studies showed that free sphingosine chains localized at the outer layers of the unit cell, while the remaining CER NS head group was concentrated in the inner headgroup layers. However, when FFA C18 was inserted, CER NS was dispersed throughout the LPP, resulting in an even distribution between the inner and outer water layers. The presented results highlight the importance of the CER NS headgroup structure and its interaction in combination with the carbon chain invariability for optimal lipid arrangement.
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Affiliation(s)
- Charlotte M Beddoes
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, University of Leiden, Leiden, the Netherlands
| | - Gert S Gooris
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, University of Leiden, Leiden, the Netherlands
| | - David J Barlow
- Division of Pharmacy and Optometry, Manchester University, Manchester, United Kingdom
| | - M Jayne Lawrence
- Division of Pharmacy and Optometry, Manchester University, Manchester, United Kingdom
| | - Robert M Dalgliesh
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, United Kingdom
| | - Marc Malfois
- ALBA Synchrotron, Carrer de la Llum 2-6, 08290 Cerdanyola del Valles, Barcelona, Spain
| | - Bruno Demé
- Institut Laue-Langevin, Grenoble, France
| | - Joke A Bouwstra
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, University of Leiden, Leiden, the Netherlands.
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3
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Ishkhanyan H, Ziolek RM, Barlow DJ, Lawrence MJ, Poghosyan AH, Lorenz CD. NSAID solubilisation promotes morphological transitions in Triton X-114 surfactant micelles. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119050] [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: 11/16/2022]
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4
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Ishkhanyan H, Rhys NH, Barlow DJ, Lawrence MJ, Lorenz CD. Impact of drug aggregation on the structural and dynamic properties of Triton X-100 micelles. Nanoscale 2022; 14:5392-5403. [PMID: 35319029 DOI: 10.1039/d1nr07936k] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Surfactants are used in a wide range of chemical and biological applications, and for pharmaceutical purposes are frequently employed to enhance the solubility of poorly water soluble drugs. In this study, all-atom molecular dynamics (MD) simulations and small-angle neutron scattering (SANS) experiments have been used to investigate the drug solubilisation capabilities of the micelles that result from 10 wt% aqueous solutions of the non-ionic surfactant, Triton X-100 (TX-100). Specifically, we have investigated the solubilisation of saturation amounts of the sodium salts of two nonsteroidal anti-inflammatory drugs: ibuprofen and indomethacin. We find that the ibuprofen-loaded micelles are more non-spherical than the indomethacin-loaded micelles which are in turn even more non-spherical than the TX-100 micelles that form in the absence of any drug. Our simulations show that the TX-100 micelles are able to solubilise twice as many indomethacin molecules as ibuprofen molecules, and the indomethacin molecules form larger aggregates in the core of the micelle than ibuprofen. These large indomethacin aggregates result in the destabilisation of the TX-100 micelle, which leads to an increase in the amount of water inside of the core of the micelle. These combined effects cause the eventual division of the indomethacin-loaded micelle into two daughter micelles. These results provide a mechanistic description of how drug interactions can affect the stability of the resulting nanoparticles.
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Affiliation(s)
- Hrachya Ishkhanyan
- Biological & Soft Matter Research Group, Department of Physics, Faculty of Natural, Mathematical & Engineering Sciences, King's College London, London, UK.
| | - Natasha H Rhys
- Biological & Soft Matter Research Group, Department of Physics, Faculty of Natural, Mathematical & Engineering Sciences, King's College London, London, UK.
| | - David J Barlow
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, UK
| | - M Jayne Lawrence
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, UK
| | - Christian D Lorenz
- Biological & Soft Matter Research Group, Department of Physics, Faculty of Natural, Mathematical & Engineering Sciences, King's College London, London, UK.
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5
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Alzoubi T, Martin GP, Barlow DJ, Royall PG. Stability of α-lactose monohydrate: The discovery of dehydration triggered solid-state epimerization. Int J Pharm 2021; 604:120715. [PMID: 34048927 DOI: 10.1016/j.ijpharm.2021.120715] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/07/2021] [Accepted: 05/14/2021] [Indexed: 10/21/2022]
Abstract
Lactose is present as an excipient in nearly half of all solid medicines. Despite the assumption of chemical stability, in aqueous solution, the chiral composition of lactose is prone to change. It is not known whether such epimerisation could also occur as solid crystalline α-lactose undergoes thermal desorption of its hydrated water. Thus, the aim of this study was to investigate the anomeric composition of lactose powders after heating in a differential scanning calorimeter. During thermal analysis, the heating cycles were interrupted to allow anomer-composition analysis by NMR. The onset for monohydrate desorption occurred at 143.8 ± 0.3 °C. Post water-loss, at 160 °C for example, α-lactose suffered partial conversion (11.6 ± 0.9%) to the β-anomer. When held at 160 °C for 60 min this increased to 29.7 ± 0.8% β-anomer (p < 0.05). This process of epimerisation was found to be close to zero-order with a rate constant of 0.28% per min-1. Optical microscopy indicated that the solid-state was maintained throughout thermal desorption and up to the onset of melting at 214.2 ± 0.9 °C. Only epimerisation was observed, with no additional chemical degradation detected by NMR. Similar results were observed when heating α-lactose to 190 °C, which resulted in a conversion of 29.1 ± 0.7% to β-lactose. Thus, the exothermic peak observed after monohydrate loss, which has often been attributed to re-crystallisation, comprises a contribution from epimerisation. No epimerisation or hydrate loss was observed for β-lactose powders when heated. In summary, it has been shown unequivocally for the first time that hydrate desorption (dehydration) leads to solid-state epimerisation in α-lactose powders.
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Affiliation(s)
- Thamer Alzoubi
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, UK; Department of Pharmaceutical Sciences, College of Health Sciences, PAAET (Public Authority for Applied Education and Training), Kuwait
| | - Gary P Martin
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, UK
| | - David J Barlow
- Division of Pharmacy & Optometry, University of Manchester, Stopford Building, 99 Oxford Road, Manchester M13 9PG, UK
| | - Paul G Royall
- Institute of Pharmaceutical Science, King's College London, London SE1 9NH, UK.
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6
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Ahmadi D, Ledder R, Mahmoudi N, Li P, Tellam J, Robinson D, Heenan RK, Smith P, Lorenz CD, Barlow DJ, Lawrence MJ. Supramolecular architecture of a multi-component biomimetic lipid barrier formulation. J Colloid Interface Sci 2021; 587:597-612. [DOI: 10.1016/j.jcis.2020.11.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 10/05/2020] [Accepted: 11/04/2020] [Indexed: 10/23/2022]
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7
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Pink DL, Loruthai O, Ziolek RM, Terry AE, Barlow DJ, Lawrence MJ, Lorenz CD. Interplay of lipid and surfactant: Impact on nanoparticle structure. J Colloid Interface Sci 2021; 597:278-288. [PMID: 33872884 DOI: 10.1016/j.jcis.2021.03.136] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/15/2021] [Accepted: 03/24/2021] [Indexed: 11/24/2022]
Abstract
Liquid lipid nanoparticles (LLN) are oil-in-water nanoemulsions of great interest in the delivery of hydrophobic drug molecules. They consist of a surfactant shell and a liquid lipid core. The small size of LLNs makes them difficult to study, yet a detailed understanding of their internal structure is vital in developing stable drug delivery vehicles (DDVs). Here, we implement machine learning techniques alongside small angle neutron scattering experiments and molecular dynamics simulations to provide critical insight into the conformations and distributions of the lipid and surfactant throughout the LLN. We simulate the assembly of a single LLN composed of the lipid, triolein (GTO), and the surfactant, Brij O10. Our work shows that the addition of surfactant is pivotal in the formation of a disordered lipid core; the even coverage of Brij O10 across the LLN shields the GTO from water and so the lipids adopt conformations that reduce crystallisation. We demonstrate the superior ability of unsupervised artificial neural networks in characterising the internal structure of DDVs, when compared to more conventional geometric methods. We have identified, clustered, classified and averaged the dominant conformations of lipid and surfactant molecules within the LLN, providing a multi-scale picture of the internal structure of LLNs.
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Affiliation(s)
- Demi L Pink
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London, WC2R 2LS, United Kingdom
| | - Orathai Loruthai
- Pharmaceutical Biophysics Group, Institute of Pharmaceutical Science, King's College London, London, SW1 9NH, United Kingdom
| | - Robert M Ziolek
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London, WC2R 2LS, United Kingdom
| | - Ann E Terry
- CoSAXS beamline, MAX IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden
| | - David J Barlow
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, United Kingdom
| | - M Jayne Lawrence
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, United Kingdom.
| | - Christian D Lorenz
- Biological Physics and Soft Matter Group, Department of Physics, King's College London, London, WC2R 2LS, United Kingdom.
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8
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Pink DL, Foglia F, Barlow DJ, Lawrence MJ, Lorenz CD. The Impact of Lipid Digestion on the Dynamic and Structural Properties of Micelles. Small 2021; 17:e2004761. [PMID: 33470509 DOI: 10.1002/smll.202004761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/02/2020] [Indexed: 06/12/2023]
Abstract
Self-assembled, lipid-based micelles, such as those formed by the short-chain phosphocholine, dihexanoylphosphatidylcholine (2C6PC), are degraded by the pancreatic enzyme, phospholipase A2 (PLA2). Degradation yields 1-hexanoyl-lysophosphocholine (C6LYSO) and hexanoic acid (C6FA) products. However, little is known about the behavior of these products during and after the degradation of 2C6PC. In this work, a combination of static and time-resolved small angle neutron scattering, as well as all-atom molecular dynamics simulations, is used to characterize the structure of 2C6PC micelles. In doing so a detailed understanding of the substrate and product aggregation behavior before, during and after degradation is gained. Consequently, the formation of mixed micelles containing 2C6PC, C6LYSO and C6FA is shown at every stage of the degradation process, as well as the formation of mixed C6LYSO/C6FA micelles after degradation is complete. The use of atomistic molecular dynamics has allowed us to characterize the structure of 2C6PC, 2C6PC/C6LYSO/C6FA, and C6LYSO/C6FA micelles throughout the degradation process, showing the localization of the different molecular species within the aggregates. In addition, the hydration of the 2C6PC, C6LYSO, and C6FA species both during micellization and as monomers in aqueous solution is documented to reveal the processes driving their micellization.
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Affiliation(s)
- Demi L Pink
- Department of Physics, King's College London, London, WC2R 2LS, UK
| | - Fabrizia Foglia
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - David J Barlow
- Faculty of Life Sciences and Medicine, King's College London, Franklin-Wilkins Building, Stamford Street, London, SE1 9NH, UK
| | - M Jayne Lawrence
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PL, UK
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9
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Sofian ZM, Benaouda F, Wang JTW, Lu Y, Barlow DJ, Royall PG, Farag DB, Rahman KM, Al-Jamal KT, Forbes B, Jones SA. A Cyclodextrin-Stabilized Spermine-Tagged Drug Triplex that Targets Theophylline to the Lungs Selectively in Respiratory Emergency. Adv Ther (Weinh) 2020; 3:2000153. [PMID: 33043128 PMCID: PMC7536984 DOI: 10.1002/adtp.202000153] [Citation(s) in RCA: 2] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/04/2020] [Indexed: 12/21/2022]
Abstract
Ion‐pairing a lifesaving drug such as theophylline with a targeting moiety could have a significant impact on medical emergencies such as status asthmaticus or COVID‐19 induced pneumomediastinum. However, to achieve rapid drug targeting in vivo the ion‐pair must be protected against breakdown before the entry into the target tissue. This study aims to investigate if inserting theophylline, when ion‐paired to the polyamine transporter substrate spermine, into a cyclodextrin (CD), to form a triplex, could direct the bronchodilator to the lungs selectively after intravenous administration. NMR demonstrates that upon the formation of the triplex spermine protruded from the CD cavity and this results in energy‐dependent uptake in A549 cells (1.8‐fold enhancement), which persists for more than 20 min. In vivo, the triplex produces a 2.4‐fold and 2.2‐fold increase in theophylline in the lungs 20 min after injection in rats and mice, respectively (p < 0.05). The lung targeting is selective with no increase in uptake into the brain or the heart where the side‐effects of theophylline are treatment‐limiting. Selectively doubling the concentration of theophylline in the lungs could improve the benefit‐risk ratio of this narrow therapeutic index medicine, which continues to be important in critical care.
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Affiliation(s)
- Zarif M Sofian
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK.,Department of Pharmaceutical Technology Faculty of Pharmacy Universiti Malaya Kuala Lumpur 50603 Malaysia
| | - Faiza Benaouda
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Julie Tzu-Wen Wang
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Yuan Lu
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - David J Barlow
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Paul G Royall
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Doaa B Farag
- Faculty of Pharmacy Misr International University Cairo 11431 Egypt
| | - Khondaker Miraz Rahman
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Khuloud T Al-Jamal
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Ben Forbes
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
| | - Stuart A Jones
- School of Cancer and Pharmaceutical Sciences Faculty of Life Sciences & Medicine King's College London Franklin-Wilkins Building, 150 Stamford Street London SE1 9NH UK
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10
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Ahmadi D, Mahmoudi N, Heenan RK, Barlow DJ, Lawrence MJ. The Influence of Co-Surfactants on Lamellar Liquid Crystal Structures Formed in Creams. Pharmaceutics 2020; 12:E864. [PMID: 32932858 PMCID: PMC7557764 DOI: 10.3390/pharmaceutics12090864] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/05/2020] [Accepted: 09/10/2020] [Indexed: 11/16/2022] Open
Abstract
It is well-established that oil-in-water creams can be stabilised through the formation of lamellar liquid crystal structures in the continuous phase, achieved by adding (emulsifier) mixtures comprising surfactant(s) combined (of necessity) with one or more co-surfactants. There is little molecular-level understanding, however, of how the microstructure of a cream is modulated by changes in co-surfactant and of the ramifications of such changes on cream properties. We investigate here the molecular architectures of oil-free, ternary formulations of water and emulsifiers comprising sodium dodecyl sulfate and one or both of the co-surfactants hexadecanol and octadecanol, using microscopy, small-angle and wide-angle X-ray scattering and small-angle neutron scattering. We then deploy these techniques to determine how the structures of the systems change when liquid paraffin oil is added to convert them to creams, and establish how the structure, rheology, and stability of the creams is modified by changing the co-surfactant. The ternary systems and their corresponding creams are shown to contain co-surfactant lamellae that are subtly different and exhibit different thermotropic behaviours. The lamellae within the creams and the layers surrounding their oil droplets are shown to vary with co-surfactant chain length. Those containing a single fatty alcohol co-surfactant are found to contain crystallites, and by comparison with the cream containing both alcohols suffer adverse changes in their rheology and stability.
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Affiliation(s)
- Delaram Ahmadi
- Institute of Pharmaceutical Science, King’s College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK;
| | - Najet Mahmoudi
- STFC ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK; (N.M.); (R.K.H.)
| | - Richard K. Heenan
- STFC ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK; (N.M.); (R.K.H.)
| | - David J. Barlow
- Institute of Pharmaceutical Science, King’s College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK;
- Division of Pharmacy & Optometry, School of Health Sciences, Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PG, UK
| | - M. Jayne Lawrence
- Division of Pharmacy & Optometry, School of Health Sciences, Stopford Building, University of Manchester, Oxford Road, Manchester M13 9PG, UK
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11
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Beddoes C, Gooris GS, Foglia F, Ahmadi D, Barlow DJ, Lawrence MJ, Demé B, Bouwstra JA. Arrangement of Ceramides in the Skin: Sphingosine Chains Localize at a Single Position in Stratum Corneum Lipid Matrix Models. Langmuir 2020; 36:10270-10278. [PMID: 32816488 PMCID: PMC7498151 DOI: 10.1021/acs.langmuir.0c01992] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Understanding the structure of the stratum corneum (SC) is essential to understand the skin barrier process. The long periodicity phase (LPP) is a unique trilayer lamellar structure located in the SC. Adjustments in the composition of the lipid matrix, as in many skin abnormalities, can have severe effects on the lipid organization and barrier function. Although the location of individual lipid subclasses has been identified, the lipid conformation at these locations remains uncertain. Contrast variation experiments via small-angle neutron diffraction were used to investigate the conformation of ceramide (CER) N-(tetracosanoyl)-sphingosine (NS) within both simplistic and porcine mimicking LPP models. To identify the lipid conformation of the twin chain CER NS, the chains were individually deuterated, and their scattering length profiles were calculated to identify their locations in the LPP unit cell. In the repeating trilayer unit of the LPP, the acyl chain of CER NS was located in the central and outer layers, while the sphingosine chain was located exclusively in the middle of the outer layers. Thus, for the CER NS with the acyl chain in the central layer, this demonstrates an extended conformation. Electron density distribution profiles identified that the lipid structure remains consistent regardless of the lipid's lateral packing phase, this may be partially due to the anchoring of the extended CER NS. The presented results provide a more detailed insight on the internal arrangement of the LPP lipids and how they are expected to be arranged in healthy skin.
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Affiliation(s)
- Charlotte
M. Beddoes
- Division
of BioTherapeutics, Leiden Academic Centre for Drug Research, University of Leiden, Einsteinweg 55, Leiden 2333 CC, The Netherlands
| | - Gert S. Gooris
- Division
of BioTherapeutics, Leiden Academic Centre for Drug Research, University of Leiden, Einsteinweg 55, Leiden 2333 CC, The Netherlands
| | - Fabrizia Foglia
- Chemistry
Department, Christopher Ingold Laboratories, University College London, London WC1H 0AJ, United Kingdom
| | - Delaram Ahmadi
- Pharmaceutical
Science Division, King’s College
London, London WC2R 2LS, United Kingdom
| | - David J. Barlow
- Pharmaceutical
Science Division, King’s College
London, London WC2R 2LS, United Kingdom
| | - M. Jayne Lawrence
- Division
of Pharmacy and Optometry, Manchester University, Manchester M13 9PL, United Kingdom
| | - Bruno Demé
- Institute
Laue-Langevin, Grenoble 38000, France
| | - Joke A. Bouwstra
- Division
of BioTherapeutics, Leiden Academic Centre for Drug Research, University of Leiden, Einsteinweg 55, Leiden 2333 CC, The Netherlands
- . Tel: 00 31 71 527 4208. Fax: 00 31 71 527 4565
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12
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Ramsden DB, Waring RH, Parsons RB, Barlow DJ, Williams AC. Nicotinamide N-Methyltransferase: Genomic Connection to Disease. Int J Tryptophan Res 2020; 13:1178646920919770. [PMID: 32547055 PMCID: PMC7273554 DOI: 10.1177/1178646920919770] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Accepted: 03/24/2020] [Indexed: 12/20/2022] Open
Abstract
Single-nucleotide polymorphisms (SNPs) in and around the nicotinamide
N-methyltransferase (NNMT) gene are associated with a range
of cancers and other diseases and conditions. The data on these associations
have been assembled, and their strength discussed. There is no evidence that the
presence of either the major or minor base in any SNP affects the expression of
nicotinamide N-methyltransferase. Nevertheless, suggestions
have been put forward that some of these SNPs do affect NNMT expression and thus
homocysteine metabolism. An alternative idea involving non-coding messenger RNAs
(mRNAs) is suggested as a possible mechanism whereby health is influenced. It is
postulated that these long, non-coding NNMT mRNAs may exert deleterious effects
by interfering with the expression of other genes. Neither hypothesis, however,
has experimental proof, and further work is necessary to elucidate NNMT genetic
interactions.
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Affiliation(s)
- David B Ramsden
- Institute of Metabolism and Systems Research, The Medical School, University of Birmingham, Birmingham, UK
| | | | - Richard B Parsons
- Institute of Pharmaceutical Science, Kings College London, London, UK
| | - David J Barlow
- Institute of Pharmaceutical Science, Kings College London, London, UK
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13
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Abstract
The rapid absorptive clearance of drugs delivered to the airways of the lungs means that many inhaled medicines have a short duration of action. The aim of this study was to investigate whether forming polar ion-pairs can modify drug absorption to slow down clearance from the airways. Salbutamol was used as a model drug and was formulated as ion-pairs in an aqueous solution with three negatively charged hydrophilic counterions: sulfate (molecular weight (MW) 142), gluconate (MW 218), and phytate (MW 736) (association constants of 1.57, 2.27, and 4.15, respectively) and one negatively charged hydrophobic counterion, octanoate (MW 166) (association constant, 2.56). All of the counterions were well tolerated by Calu-3 human bronchial epithelial cells when screened for toxicity in vitro using conditions that in silico simulations suggested maintain >80% drug-counterion association. The transport of salbutamol ion-pairs with higher polar surface area (PSA), i.e., the sulfate (PSA 52%), gluconate (PSA 50%), and phytate (PSA 79%) ion-pairs, was significantly lower compared to that of the drug alone (PSA 30%, p < 0.05). In contrast, the octanoate ion-pair (PSA 23%) did not significantly alter the salbutamol transport. The transport data for the gluconate ion-pair suggested that the pulmonary absorption half-life of the ion-paired drug would be double that of salbutamol base, and this illustrates the promise of increasing drug polarity using noncovalent complexation as an approach to control drug delivery to the airways of the lungs.
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Affiliation(s)
- Bridie Dutton
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, U.K
| | - Arcadia Woods
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, U.K
| | - Robyn Sadler
- GlaxoSmithKline, Park Road, Ware, Hertfordshire SG12 0DP, U.K
| | - David Prime
- GlaxoSmithKline, Park Road, Ware, Hertfordshire SG12 0DP, U.K
| | - David J Barlow
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, U.K
| | - Ben Forbes
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, U.K
| | - Stuart A Jones
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, 150 Stamford Street, London SE1 9NH, U.K
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14
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Spizzichino S, Mattedi G, Lauder K, Valle C, Aouadi W, Canard B, Decroly E, Kaptein SJF, Neyts J, Graham C, Sule Z, Barlow DJ, Silvestri R, Castagnolo D. Design, Synthesis and Discovery of N,N'-Carbazoyl-aryl-urea Inhibitors of Zika NS5 Methyltransferase and Virus Replication. ChemMedChem 2020; 15:385-390. [PMID: 31805205 PMCID: PMC7106487 DOI: 10.1002/cmdc.201900533] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/05/2019] [Indexed: 12/18/2022]
Abstract
The recent outbreaks of Zika virus (ZIKV) infection worldwide make the discovery of novel antivirals against flaviviruses a research priority. This work describes the identification of novel inhibitors of ZIKV through a structure-based virtual screening approach using the ZIKV NS5-MTase. A novel series of molecules with a carbazoyl-aryl-urea structure has been discovered and a library of analogues has been synthesized. The new compounds inhibit ZIKV MTase with IC50 between 23-48 μM. In addition, carbazoyl-aryl-ureas also proved to inhibit ZIKV replication activity at micromolar concentration.
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Affiliation(s)
- Sharon Spizzichino
- School of Cancer and Pharmaceutical SciencesKing's College LondonLondonSE1 9NHUK
- Department of Drug Chemistry and TechnologiesSapienza University of RomeLaboratory Affiliated to Instituto Pasteur Italia – Fondazione Cenci BolognettiPiazzale Aldo Moro 500185RomaItaly
| | - Giulio Mattedi
- School of Cancer and Pharmaceutical SciencesKing's College LondonLondonSE1 9NHUK
| | - Kate Lauder
- School of Cancer and Pharmaceutical SciencesKing's College LondonLondonSE1 9NHUK
| | - Coralie Valle
- AFMB, CNRSAix-Marseille University UMR 7257, Case 925163 Avenue de Luminy13288Marseille Cedex 09France
| | - Wahiba Aouadi
- AFMB, CNRSAix-Marseille University UMR 7257, Case 925163 Avenue de Luminy13288Marseille Cedex 09France
| | - Bruno Canard
- AFMB, CNRSAix-Marseille University UMR 7257, Case 925163 Avenue de Luminy13288Marseille Cedex 09France
| | - Etienne Decroly
- AFMB, CNRSAix-Marseille University UMR 7257, Case 925163 Avenue de Luminy13288Marseille Cedex 09France
| | - Suzanne J. F. Kaptein
- Department of Microbiology, Immunology and Transplantation Rega Institute for Medical Research Laboratory of Virology and ChemotherapyKU LeuvenMinderbroedersstraat 103000LeuvenBelgium
| | - Johan Neyts
- Department of Microbiology, Immunology and Transplantation Rega Institute for Medical Research Laboratory of Virology and ChemotherapyKU LeuvenMinderbroedersstraat 103000LeuvenBelgium
| | - Carl Graham
- School of Cancer and Pharmaceutical SciencesKing's College LondonLondonSE1 9NHUK
| | - Zakary Sule
- School of Cancer and Pharmaceutical SciencesKing's College LondonLondonSE1 9NHUK
| | - David J. Barlow
- School of Cancer and Pharmaceutical SciencesKing's College LondonLondonSE1 9NHUK
| | - Romano Silvestri
- Department of Drug Chemistry and TechnologiesSapienza University of RomeLaboratory Affiliated to Instituto Pasteur Italia – Fondazione Cenci BolognettiPiazzale Aldo Moro 500185RomaItaly
| | - Daniele Castagnolo
- School of Cancer and Pharmaceutical SciencesKing's College LondonLondonSE1 9NHUK
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15
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Brauer R, Herrero-Zazo M, Barlow DJ, Gaughran F, Taylor D, Howard LM. Minocycline and the risk of acute psychiatric events in adolescence: A self-controlled case series. J Psychopharmacol 2019; 33:466-471. [PMID: 30696331 DOI: 10.1177/0269881118821852] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Minocycline has neurological anti-inflammatory properties and has been hypothesised to have antipsychotic effects. AIM The aim of this study was to investigate, using routinely collected United Kingdom primary health care data, whether adolescent men and women are more or less likely to receive an urgent psychiatric referral during treatment for acne with minocycline compared with periods of non-treatment. METHOD A self-controlled case series using United Kingdom Clinical Practice Research Datalink to calculate the incidence rate ratio of urgent psychiatric referrals for individuals, comparing periods during which minocycline was prescribed with unexposed periods, adjusted for age. RESULTS We found 167 individuals who were at the time exposed to minocycline for a mean of 99 days and who received an urgent psychiatric referral. There was no difference in psychiatric referral risk during periods of exposure compared with periods of non-exposure: incidence rate ratio first 6 weeks of exposure 1.96, 95% confidence interval 0.82-4.71, p=0.132; incidence rate ratio remaining exposure period=1.97, 95% confidence interval 0.86-4.47, p=0.107. CONCLUSIONS We found no evidence in support of a protective effect of minocycline against severe psychiatric symptoms in adolescence.
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Affiliation(s)
- Ruth Brauer
- 1 Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.,2 Research Department of Practice and Policy, School of Pharmacy, University College London, London, UK
| | - Maria Herrero-Zazo
- 3 Department of Pharmacy and Forensic Science, Institute of Pharmaceutical Science, King's College London, London, UK
| | - David J Barlow
- 3 Department of Pharmacy and Forensic Science, Institute of Pharmaceutical Science, King's College London, London, UK
| | - Fiona Gaughran
- 1 Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.,4 South London and Maudsley NHS Foundation Trust, London, UK
| | - David Taylor
- 1 Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.,3 Department of Pharmacy and Forensic Science, Institute of Pharmaceutical Science, King's College London, London, UK.,4 South London and Maudsley NHS Foundation Trust, London, UK
| | - Louise M Howard
- 1 Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.,4 South London and Maudsley NHS Foundation Trust, London, UK
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16
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Mohammadi A, Kudsiova L, Mustapa MFM, Campbell F, Vlaho D, Welser K, Story H, Tagalakis AD, Hart SL, Barlow DJ, Tabor AB, Lawrence MJ, Hailes HC. The discovery and enhanced properties of trichain lipids in lipopolyplex gene delivery systems. Org Biomol Chem 2019; 17:945-957. [PMID: 30629080 PMCID: PMC6350505 DOI: 10.1039/c8ob02374c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Novel trichain lipids have been identified with enhanced transfection properties in lipopolyplexes.
The formation of a novel trichain (TC) lipid was discovered when a cationic lipid possessing a terminal hydroxyl group and the helper lipid dioleoyl l-α-phosphatidylethanolamine (DOPE) were formulated as vesicles and stored. Importantly, the transfection efficacies of lipopolyplexes comprised of the TC lipid, a targeting peptide and DNA (LPDs) were found to be higher than when the corresponding dichain (DC) lipid was used. To explore this interesting discovery and determine if this concept can be more generally applied to improve gene delivery efficiencies, the design and synthesis of a series of novel TC cationic lipids and the corresponding DC lipids was undertaken. Transfection efficacies of the LPDs were found to be higher when using the TC lipids compared to the DC analogues, so experiments were carried out to investigate the reasons for this enhancement. Sizing experiments and transmission electron microscopy indicated that there were no major differences in the size and shape of the LPDs prepared using the TC and DC lipids, while circular dichroism spectroscopy showed that the presence of the third acyl chain did not influence the conformation of the DNA within the LPD. In contrast, small angle neutron scattering studies showed a considerable re-arrangement of lipid conformation upon formulation as LPDs, particularly of the TC lipids, while gel electrophoresis studies revealed that the use of a TC lipid in the LPD formulation resulted in enhanced DNA protection properties. Thus, the major enhancement in transfection performance of these novel TC lipids can be attributed to their ability to protect and subsequently release DNA. Importantly, the TC lipids described here highlight a valuable structural template for the generation of gene delivery vectors, based on the use of lipids with three hydrophobic chains.
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Affiliation(s)
- Atefeh Mohammadi
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
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17
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Kudsiova L, Mohammadi A, Mustapa MFM, Campbell F, Welser K, Vlaho D, Story H, Barlow DJ, Tabor AB, Hailes HC, Lawrence MJ. Trichain cationic lipids: the potential of their lipoplexes for gene delivery. Biomater Sci 2018; 7:149-158. [PMID: 30357152 PMCID: PMC6336150 DOI: 10.1039/c8bm00965a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/06/2018] [Indexed: 11/21/2022]
Abstract
Lipoplexes (LDs) have been prepared from DNA and positively charged vesicles composed of the helper lipid, dioleoyl l-α-phosphatidylethanolamine (DOPE) and either a dichain (DC) oxyethylated cationic lipid or their corresponding novel trichain (TC) counterpart. This is the first study using the TC lipids for the preparation of LDs and their application. Here the results of biophysical experiments characterising the LDs have been correlated with the in vitro transfection activity of the complexes. Photon correlation spectroscopy, zeta potential measurements and transmission electron microscopy studies indicated that, regardless of the presence of a third chain, there were little differences between the size and charge of the TC and DC containing LDs. Small angle neutron scattering studies established however that there was a significant conformational re-arrangement of the lipid bilayer when in the form of a LD complex as opposed to the parent vesicles. This re-arrangement was particularly noticeable in LDs containing TC lipids possessing a third chain of C12 or a longer chain. These results suggested that the presence of a third hydrophobic chain had a significant effect on lipid packing in the presence of DNA. Picogreen fluorescence and gel electrophoresis studies showed that the TC lipids containing a third acyl chain of at least C12 were most effective at complexing DNA while the TC lipids containing an octanoyl chain and the DC lipids were least effective. The transfection efficacies of the TC lipids in the form of LDs were found to be higher than for the DC analogues, particularly when the third acyl chain was an octanoyl or oleoyl moeity. Little or no increase in transfection efficiency was observed when the third chain was a methyl, acetyl or dodecanoyl group. The large enhancement in transfection performance of the TC lipids can be attributed to their ability to complex their DNA payload. These studies indicate that presence of a medium or long third acyl chain was especially beneficial for transfection.
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Affiliation(s)
- Laila Kudsiova
- Institute of Pharmaceutical Sciences. Faculty of Life Sciences and Medicine, King's College London, Franklin-Wilkins Building, Stamford Street, London SE1 9NH, UK
| | - Atefeh Mohammadi
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - M Firouz Mohd Mustapa
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Frederick Campbell
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Katharina Welser
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Danielle Vlaho
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Harriet Story
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - David J Barlow
- Institute of Pharmaceutical Sciences. Faculty of Life Sciences and Medicine, King's College London, Franklin-Wilkins Building, Stamford Street, London SE1 9NH, UK
| | - Alethea B Tabor
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - Helen C Hailes
- Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ, UK.
| | - M Jayne Lawrence
- Institute of Pharmaceutical Sciences. Faculty of Life Sciences and Medicine, King's College London, Franklin-Wilkins Building, Stamford Street, London SE1 9NH, UK and Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, Stopford Building, University of Manchester, Oxford Road, Manchester, M13 9PT, UK.
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18
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Gacesa R, Lawrence KP, Georgakopoulos ND, Yabe K, Dunlap WC, Barlow DJ, Wells G, Young AR, Long PF. The mycosporine-like amino acids porphyra-334 and shinorine are antioxidants and direct antagonists of Keap1-Nrf2 binding. Biochimie 2018; 154:35-44. [PMID: 30071261 PMCID: PMC6214812 DOI: 10.1016/j.biochi.2018.07.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 07/27/2018] [Indexed: 12/15/2022]
Abstract
Mycosporine-like amino acids (MAAs) are UVR-absorbing metabolites typically produced by cyanobacteria and marine algae, but their properties are not limited to direct sun screening protection. Herein, we examine the antioxidant activities of porphyra-334 and shinorine and demonstrate that these MAAs are prospective activators of the cytoprotective Keap1-Nrf2 pathway. The ability of porphyra-334 and shinorine to bind with Keap1 was determined using fluorescence polarization (FP) and thermal shift assays to detect Keap1 receptor antagonism. Concomitantly, the ability of porphyra-334 and shinorine to dissociate Nrf2 from Keap1 was confirmed also by measurement of increased mRNA expression of Nrf2 targeted genes encoding oxidative stress defense proteins in primary skin fibroblasts prior and post UVR exposure. Surprisingly, enhanced transcriptional regulation was only promoted by MAAs in cells after exposure to UVR-induced oxidative stress. Furthermore, the in-vitro antioxidant activities of porphyra-334 and shinorine determined by the DPPH free-radical quenching assay were low in comparison to ascorbic acid. However, their antioxidant capacity determined by the ORAC assay to quench free radicals via hydrogen atom transfer is substantial. Hence, the dual nature of MAAs to provide antioxidant protection may offer a prospective chemotherapeutic strategy to prevent or retard the progression of multiple degenerative disorders of ageing.
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Affiliation(s)
- Ranko Gacesa
- Faculty of Life Sciences & Medicine, King's College London, United Kingdom
| | - Karl P Lawrence
- Faculty of Life Sciences & Medicine, King's College London, United Kingdom
| | | | - Kazuo Yabe
- Chemical Laboratory, Hokkaido University of Education, Japan
| | - Walter C Dunlap
- Faculty of Life Sciences & Medicine, King's College London, United Kingdom
| | - David J Barlow
- Faculty of Life Sciences & Medicine, King's College London, United Kingdom
| | - Geoffrey Wells
- School of Pharmacy, University College London, United Kingdom
| | - Antony R Young
- Faculty of Life Sciences & Medicine, King's College London, United Kingdom
| | - Paul F Long
- Faculty of Life Sciences & Medicine, King's College London, United Kingdom.
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19
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Herrero-Zazo M, Brauer R, Gaughran F, Howard LM, Taylor D, Barlow DJ. Examining the potential preventative effects of minocycline prescribed for acne on the incidence of severe mental illnesses: A historical cohort study. J Psychopharmacol 2018; 32:559-568. [PMID: 29215319 DOI: 10.1177/0269881117743483] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Animal studies suggest that the antibiotic and microglial activation inhibitor, minocycline, is likely to have a protective effect against the emergence of psychosis but evidence from human studies is lacking. The aim of this study is to examine the effects of exposure to minocycline during adolescence on the later incidence of severe mental illness (SMI). METHODS A historical cohort study using electronic primary care data was conducted to assess the association between exposure to minocycline during adolescence and incidence of SMI. The Incidence Rate Ratio (IRR) was measured using Poisson regression adjusted for age, gender, time of exposure, socioeconomic deprivation status, calendar year and co-medications. RESULTS Early minocycline prescription ( n=13,248) did not affect the incidence of SMI compared with non-prescription of minocycline ( n=14,393), regardless of gender or whether or not the data were filtered according to a minimum exposure period (minimum period: IRR 0.96; 95% CI 0.68-1.36; p=0.821; no minimum period: IRR 1.08; 95% CI 0.83-1.42; p=0.566). CONCLUSIONS Exposure to minocycline for acne treatment during adolescence appears to have no effect on the incidence of SMI.
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Affiliation(s)
- Maria Herrero-Zazo
- 1 Department of Pharmacy and Forensic Science, Institute of Pharmaceutical Science, King's College London, UK
| | - Ruth Brauer
- 2 Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK.,3 Research Department of Practice and Policy, School of Pharmacy, University College London, UK
| | - Fiona Gaughran
- 2 Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK.,4 South London and Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Beckenham, Kent, UK
| | - Louise M Howard
- 2 Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK.,4 South London and Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Beckenham, Kent, UK
| | - David Taylor
- 1 Department of Pharmacy and Forensic Science, Institute of Pharmaceutical Science, King's College London, UK.,2 Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK.,4 South London and Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Beckenham, Kent, UK
| | - David J Barlow
- 1 Department of Pharmacy and Forensic Science, Institute of Pharmaceutical Science, King's College London, UK
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20
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van Haren MJ, Thomas MG, Sartini D, Barlow DJ, Ramsden DB, Emanuelli M, Klamt F, Martin NI, Parsons RB. The kinetic analysis of the N-methylation of 4-phenylpyridine by nicotinamide N-methyltransferase: Evidence for a novel mechanism of substrate inhibition. Int J Biochem Cell Biol 2018; 98:127-136. [PMID: 29549048 DOI: 10.1016/j.biocel.2018.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [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: 09/27/2017] [Revised: 02/23/2018] [Accepted: 03/12/2018] [Indexed: 12/17/2022]
Abstract
The N-methylation of 4-phenylpyridine produces the neurotoxin 1-methyl-4-phenylpyridinium ion (MPP+). We investigated the kinetics of 4-phenylpyridine N-methylation by nicotinamide N-methyltransferase (NNMT) and its effect upon 4-phenylpyridine toxicity in vitro. Human recombinant NNMT possessed 4-phenylpyridine N-methyltransferase activity, with a specific activity of 1.7 ± 0.03 nmol MPP+ produced/h/mg NNMT. Although the Km for 4-phenylpyridine was similar to that reported for nicotinamide, its kcat of 9.3 × 10-5 ± 2 × 10-5 s-1 and specificity constant, kcat/Km, of 0.8 ± 0.8 s-1 M-1 were less than 0.15% of the respective values for nicotinamide, demonstrating that 4-phenylpyridine is a poor substrate for NNMT. At low (<2.5 mM) substrate concentration, 4-phenylpyridine N-methylation was competitively inhibited by dimethylsulphoxide, with a Ki of 34 ± 8 mM. At high (>2.5 mM) substrate concentration, enzyme activity followed substrate inhibition kinetics, with a Ki of 4 ± 1 mM. In silico molecular docking suggested that 4-phenylpyridine binds to the active site of NNMT in two non-redundant poses, one a substrate binding mode and the other an inhibitory mode. Finally, the expression of NNMT in the SH-SY5Y cell-line had no effect cell death, viability, ATP content or mitochondrial membrane potential. These data demonstrate that 4-phenylpyridine N-methylation by NNMT is unlikely to serve as a source of MPP+. The possibility for competitive inhibition by dimethylsulphoxide should be considered in NNMT-based drug discovery studies. The potential for 4-phenylpyridine to bind to the active site in two binding orientations using the same active site residues is a novel mechanism of substrate inhibition.
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Affiliation(s)
- Matthijs J van Haren
- Utrecht University, Utrecht Institute for Pharmaceutical Science, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | - Martin G Thomas
- King's College London, Institute of Pharmaceutical Science, 150 Stamford Street, London SE1 9NH, UK
| | - Davide Sartini
- Universitá Politecnica delle Marche, Department of Clinical Sciences, School of Medicine, Ancona, Italy
| | - David J Barlow
- King's College London, Institute of Pharmaceutical Science, 150 Stamford Street, London SE1 9NH, UK
| | - David B Ramsden
- University of Birmingham, Institute of Metabolism and Systems Research, Edgbaston, Birmingham B15 2TH, UK
| | - Monica Emanuelli
- Universitá Politecnica delle Marche, Department of Clinical Sciences, School of Medicine, Ancona, Italy
| | - Fábio Klamt
- Universidade Federal do Rio Grande do Sul, Departmento de Bioquímica, Instituto de Ciêncas Básicas de Saúde, Rua Ramiro Barcelos, Porto Alegre, RS 90035 003, Brazil
| | - Nathaniel I Martin
- Utrecht University, Utrecht Institute for Pharmaceutical Science, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
| | - Richard B Parsons
- King's College London, Institute of Pharmaceutical Science, 150 Stamford Street, London SE1 9NH, UK.
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21
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Benaouda F, Jones SA, Chana J, Dal Corno BM, Barlow DJ, Hider RC, Page CP, Forbes B. Ion-Pairing with Spermine Targets Theophylline To the Lungs via the Polyamine Transport System. Mol Pharm 2018; 15:861-870. [DOI: 10.1021/acs.molpharmaceut.7b00715] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Faiza Benaouda
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Stuart A. Jones
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Jasminder Chana
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Benedetta M. Dal Corno
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - David J. Barlow
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Robert C. Hider
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Clive P. Page
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
- Sackler Institute of Pulmonary Pharmacology, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Ben Forbes
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
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22
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Damiati SA, Martini LG, Smith NW, Lawrence MJ, Barlow DJ. Application of machine learning in prediction of hydrotrope-enhanced solubilisation of indomethacin. Int J Pharm 2017; 530:99-106. [DOI: 10.1016/j.ijpharm.2017.07.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/28/2017] [Accepted: 07/15/2017] [Indexed: 12/21/2022]
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23
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Ramsden DB, Waring RH, Barlow DJ, Parsons RB. Nicotinamide N-Methyltransferase in Health and Cancer. Int J Tryptophan Res 2017; 10:1178646917691739. [PMID: 35185340 PMCID: PMC8851132 DOI: 10.1177/1178646917691739] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 01/11/2017] [Indexed: 12/19/2022] Open
Abstract
Over the past decade, the roles of nicotinamide N-methyltransferase and its product 1-methyl nicotinamide have emerged from playing merely minor roles in phase 2 xenobiotic metabolism as actors in some of the most important scenes of human life. In this review, the structures of the gene, messenger RNA, and protein are discussed, together with the role of the enzyme in many of the common cancers that afflict people today.
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Affiliation(s)
- David B Ramsden
- Institute of Metabolism and Systems Research, The Medical School, University of Birmingham, Birmingham, UK
| | | | - David J Barlow
- Institute of Pharmaceutical Science, King’s College London, London, UK
| | - Richard B Parsons
- Institute of Pharmaceutical Science, King’s College London, London, UK
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24
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Perkins SJ, Wright DW, Zhang H, Brookes EH, Chen J, Irving TC, Krueger S, Barlow DJ, Edler KJ, Scott DJ, Terrill NJ, King SM, Butler PD, Curtis JE. Atomistic modelling of scattering data in the Collaborative Computational Project for Small Angle Scattering (CCP-SAS). J Appl Crystallogr 2016; 49:1861-1875. [PMID: 27980506 PMCID: PMC5139988 DOI: 10.1107/s160057671601517x] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 09/26/2016] [Indexed: 11/10/2022] Open
Abstract
The capabilities of current computer simulations provide a unique opportunity to model small-angle scattering (SAS) data at the atomistic level, and to include other structural constraints ranging from molecular and atomistic energetics to crystallography, electron microscopy and NMR. This extends the capabilities of solution scattering and provides deeper insights into the physics and chemistry of the systems studied. Realizing this potential, however, requires integrating the experimental data with a new generation of modelling software. To achieve this, the CCP-SAS collaboration (http://www.ccpsas.org/) is developing open-source, high-throughput and user-friendly software for the atomistic and coarse-grained molecular modelling of scattering data. Robust state-of-the-art molecular simulation engines and molecular dynamics and Monte Carlo force fields provide constraints to the solution structure inferred from the small-angle scattering data, which incorporates the known physical chemistry of the system. The implementation of this software suite involves a tiered approach in which GenApp provides the deployment infrastructure for running applications on both standard and high-performance computing hardware, and SASSIE provides a workflow framework into which modules can be plugged to prepare structures, carry out simulations, calculate theoretical scattering data and compare results with experimental data. GenApp produces the accessible web-based front end termed SASSIE-web, and GenApp and SASSIE also make community SAS codes available. Applications are illustrated by case studies: (i) inter-domain flexibility in two- to six-domain proteins as exemplified by HIV-1 Gag, MASP and ubiquitin; (ii) the hinge conformation in human IgG2 and IgA1 antibodies; (iii) the complex formed between a hexameric protein Hfq and mRNA; and (iv) synthetic 'bottlebrush' polymers.
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Affiliation(s)
- Stephen J. Perkins
- Department of Structural and Molecular Biology, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
| | - David W. Wright
- Department of Structural and Molecular Biology, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
| | - Hailiang Zhang
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-8562, USA
| | - Emre H. Brookes
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
| | - Jianhan Chen
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Thomas C. Irving
- Department of Biology, Illinois Institute of Technology, 3101 S. Dearborn, Chicago, IL 60616, USA
| | - Susan Krueger
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-8562, USA
| | - David J. Barlow
- Pharmacy Department, Franklin-Wilkins Building, King’s College London, 150 Stamford Street, London SE1 9NH, UK
| | - Karen J. Edler
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - David J. Scott
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK
- Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0FA, UK
- ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK
| | - Nicholas J. Terrill
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Chilton, Didcot, Oxfordshire OX11 0DE, UK
| | - Stephen M. King
- ISIS Facility, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, UK
| | - Paul D. Butler
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-8562, USA
- Department of Chemistry, The University of Tennessee, Knoxville, TN 37996-1600, USA
| | - Joseph E. Curtis
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-8562, USA
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25
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Knyght I, Clifton L, Saaka Y, Lawrence MJ, Barlow DJ. Interaction of the Antimicrobial Peptides Rhesus θ-Defensin and Porcine Protegrin-1 with Anionic Phospholipid Monolayers. Langmuir 2016; 32:7403-10. [PMID: 27357217 DOI: 10.1021/acs.langmuir.6b01688] [Citation(s) in RCA: 10] [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] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A combination of Langmuir isotherm, Brewster angle microscopy (BAM), and neutron reflectivity studies have been performed to gain insight into the effects on model bacterial cell membranes of the antimicrobial peptides, Rhesus θ-defensin 1 (RTD-1), and porcine protegrin 1 (PG-1). The peptides were interacted with monolayers spread at the air-water interface and prepared from a 3:1 molar mixture of phosphatidylethanolamine and phosphatidylglycerol used to approximate the cell membranes of Gram positive bacteria. The Langmuir film balance measurements show that both peptides perturb the lipid monolayers causing an increase in surface pressure, and the BAM studies show that each results in the formation of small domains within the lipid films, around 5 μm diameter. The overall change in monolayer surface pressure caused by PG-1, however, is a little more pronounced than that due to RTD-1 (+8.5 mN·m(-1) vs +5.5 mN·m(-1)), and the rate of its initial interaction with the monolayer is a little more rapid than that for RTD-1. The neutron reflectivity studies also show differences for PG-1 and RTD-1, with the model fits to these data showing that the more amphiphilic PG-1 becomes fully embedded within the lipid film-causing an extension of the lipid acyl chains but leaving the thickness of the lipid headgroup layer unaffected-while RTD-1 is seen to insert less deeply-causing the same extension of the lipid acyl chains as PG-1 but also causing a significant increase in thickness of the lipid headgroup layer. The various differing effects of the two peptides on anionic lipid monolayers are discussed in the context of their differing hemolytic activities, and their proposed differing propensities to form transmembrane pores.
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Affiliation(s)
- Ivana Knyght
- Institute of Pharmaceutical Science, King's College London , London SE1 9NH, United Kingdom
| | - Luke Clifton
- Rutherford Appleton Laboratory, ISIS Spallation Neutron Source, Harwell OX11 0QX, United Kingdom
| | - Yussif Saaka
- Institute of Pharmaceutical Science, King's College London , London SE1 9NH, United Kingdom
| | - M Jayne Lawrence
- Institute of Pharmaceutical Science, King's College London , London SE1 9NH, United Kingdom
| | - David J Barlow
- Institute of Pharmaceutical Science, King's College London , London SE1 9NH, United Kingdom
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26
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Mojumdar EH, Gooris GS, Barlow DJ, Lawrence MJ, Deme B, Bouwstra JA. Skin lipids: localization of ceramide and fatty acid in the unit cell of the long periodicity phase. Biophys J 2016; 108:2670-9. [PMID: 26039168 DOI: 10.1016/j.bpj.2015.04.030] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 03/17/2015] [Accepted: 04/21/2015] [Indexed: 12/22/2022] Open
Abstract
The lipid matrix of the skin's stratum corneum plays a key role in the barrier function, which protects the body from desiccation. The lipids that make up this matrix consist of ceramides, cholesterol, and free fatty acids, and can form two coexisting crystalline lamellar phases: the long periodicity phase (LPP) and the short periodicity phase (SPP). To fully understand the skin barrier function, information on the molecular arrangement of the lipids in the unit cell of these lamellar phases is very desirable. To determine this arrangement in previous studies, we examined the molecular arrangement of the SPP. In this study, neutron diffraction studies were performed to obtain information on the molecular arrangement of the LPP. The diffraction pattern reveals nine diffraction orders attributed to the LPP with a repeating unit of 129.4 ± 0.5 Å. Using D2O/H2O contrast variation, the scattering length density profiles were calculated for protiated samples and samples that included either the perdeuterated acyl chain of the most abundant ceramide or the most abundant perdeuterated fatty acid. Both perdeuterated chains are predominantly located in the central part of the unit cell with substantial interdigitation of the acyl chains in the unit cell center. However, a fraction of the perdeuterated chains is also located near the border of the unit cell with their acyl chains directing toward the center. This arrangement of lipids in the LPP unit cell corresponds with the location of their lipid headgroups at the border and also inside of the unit cell at a well-defined position (±21 Å from the unit cell center), indicative of a three-layer lipid arrangement within the 129.4 ± 0.5 Å repeating unit.
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Affiliation(s)
- Enamul H Mojumdar
- Leiden Academic Centre for Drug Research, Department of Drug Delivery Technology, Gorlaeus Laboratories, University of Leiden, Leiden, the Netherlands
| | - Gert S Gooris
- Leiden Academic Centre for Drug Research, Department of Drug Delivery Technology, Gorlaeus Laboratories, University of Leiden, Leiden, the Netherlands
| | - David J Barlow
- Pharmaceutical Science Division, King's College London, London, United Kingdom
| | - M Jayne Lawrence
- Pharmaceutical Science Division, King's College London, London, United Kingdom
| | - Bruno Deme
- Institute Laue-Langevin, Grenoble, France
| | - Joke A Bouwstra
- Leiden Academic Centre for Drug Research, Department of Drug Delivery Technology, Gorlaeus Laboratories, University of Leiden, Leiden, the Netherlands.
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27
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Foglia F, Rogers SE, Webster JRP, Akeroyd FA, Gascoyne KF, Lawrence MJ, Barlow DJ. Neutron Scattering Studies of the Effects of Formulating Amphotericin B with Cholesteryl Sulfate on the Drug's Interactions with Phospholipid and Phospholipid-Sterol Membranes. Langmuir 2015; 31:8042-8051. [PMID: 26139630 DOI: 10.1021/acs.langmuir.5b01365] [Citation(s) in RCA: 6] [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: 06/04/2023]
Abstract
Langmuir surface pressure, small-angle neutron scattering (SANS), and neutron reflectivity (NR) studies have been performed to determine how formulation of the antifungal drug amphotericin B (AmB), with sodium cholesteryl sulfate (SCS)-as in Amphotec-affects its interactions with ergosterol-containing (model fungal cell) and cholesterol-containing (model mammalian cell) membranes. The effects of mixing AmB in 1:1 molar ratio with cholesteryl sulfate (yielding AmB-SCS micelles) are compared against those of free AmB, using monolayers and bilayers formed from palmitoyloleoylphosphatidylcholine (POPC) in the absence and presence of 30 mol % ergosterol or cholesterol, in all cases employing a 1:0.05 molar ratio of lipid:AmB. Analyses of the (bilayer) SANS and (monolayer) NR data indicate that the equilibrium changes in membrane structure induced in sterol-free and sterol-containing membranes are the same for free AmB and AmB-SCS. Stopped-flow SANS experiments, however, reveal that the structural changes to vesicle membranes occur far more rapidly following exposure to AmB-SCS vs free drug, with the kinetics of these changes varying with membrane composition. With POPC vesicles, the structural changes induced by AmB-SCS become apparent only after several minutes, and equilibrium is reached after ∼30 min. The corresponding onset of changes in POPC-ergosterol and POPC-cholesterol vesicles, however, occurs within ∼5 s, with equilibrium reached after 10 and 120 s, respectively. The rate of insertion of AmB into POPC-sterol membranes is thus increased through formulation as AmB-SCS. Moreover, the differences in monolayer surface pressure and SANS structure-change equilibration times suggest significant rearrangement of AmB within these membranes following insertion. The reduced times to equilibrium for the POPC-ergosterol vs POPC-cholesterol systems are consistent with the known differences in affinity of AmB for these two sterols, and the reduced time to equilibrium for AmB-SCS interaction with POPC-ergosterol membranes vs that for free AmB is consistent with the reduced host toxicity of Amphotec.
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Affiliation(s)
- F Foglia
- †Institute of Pharmaceutical Science, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | | | | | | | | | - M J Lawrence
- †Institute of Pharmaceutical Science, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
| | - D J Barlow
- †Institute of Pharmaceutical Science, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, U.K
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28
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Abstract
Langmuir isotherm, neutron reflectivity, and Brewster angle microscopy experiments have been performed to study the interaction of amphotericin B (AmB) with monolayers prepared from 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and mixtures of this lipid with cholesterol or ergosterol to mimic mammalian and fungal cell membranes, respectively. Isotherm data show that AmB causes a more pronounced change in surface pressure in the POPC/ergosterol system than in the POPC and POPC/cholesterol systems, and its interaction with the POPC/ergosterol monolayer is also more rapid than with the POPC and POPC/cholesterol monolayers. Brewster angle microscopy shows that, in interaction with POPC monolayers, AmB causes the formation of small domains which shrink and disappear within a few minutes. The drug also causes domain formation in the POPC/cholesterol and POPC/ergosterol monolayers; in the former case, these are formed more slowly than is seen with the POPC monolayers and are ultimately much smaller; in the latter case, they are formed rather more quickly and are more heterogeneous in size. Neutron reflectivity data show that the changes in monolayer structure following interaction with AmB are the same for all three systems studied: the data are consistent with the drug inserting into the monolayers with its macrocyclic ring intercalated among the lipid acyl chains and sterol ring systems, with its mycosamine moiety colocalizing with the sterol hydroxyl and POPC head groups. On the basis of these studies, it is concluded that AmB inserts in a similar manner into POPC, POPC/cholesterol, and POPC/ergosterol monolayers but does so with differing kinetics and with the formation of quite different in-plane structures. The more rapid time scale for interaction of the drug with the POPC/ergosterol monolayer, its more pronounced effect on monolayer surface pressure, and its more marked changes as regards domain formation are all consistent with the drug's selectivity for fungal vs mammalian cell membranes.
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Affiliation(s)
- F Foglia
- Institute of Pharmaceutical Science, King's College London , Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK
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29
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Dabkowska AP, Collins LE, Barlow DJ, Barker R, McLain SE, Lawrence MJ, Lorenz CD. Modulation of dipalmitoylphosphatidylcholine monolayers by dimethyl sulfoxide. Langmuir 2014; 30:8803-8811. [PMID: 25000494 DOI: 10.1021/la501275h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The action of the penetration-enhancing agent, dimethyl sulfoxide (DMSO), on phospholipid monolayers was investigated at the air-water interface using a combination of experimental techniques and molecular dynamics simulations. Brewster angle microscopy revealed that DPPC monolayers remained laterally homogeneous at subphase concentrations up to a mole fraction of 0.1 DMSO. Neutron reflectometry of the monolayers in combination with isotopic substitution enabled the determination of solvent profiles as a function of distance perpendicular to the interface for the different DMSO subphase concentrations. These experimental results were compared to those obtained from molecular dynamic (MD) simulations of the corresponding monolayer systems. There was excellent agreement found between the MD-derived reflectivity curves and the measured data for all of the H/D contrast variations investigated. The MD provide a detailed description of the distribution of water and DMSO molecules around the phosphatidylcholine headgroup, and how this distribution changes with increasing DMSO concentrations. Significantly, the measurements and simulations that are reported here support the hypothesis that DMSO acts by dehydrating the phosphatidylcholine headgroup, and as such provide the first direct evidence that it does so primarily by displacing water molecules bound to the choline group.
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Affiliation(s)
- Aleksandra P Dabkowska
- Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College London , 150 Stamford Street, London, SE1 9NH, United Kingdom
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30
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Mojumdar EH, Groen D, Gooris GS, Barlow DJ, Lawrence MJ, Deme B, Bouwstra JA. Localization of cholesterol and fatty acid in a model lipid membrane: a neutron diffraction approach. Biophys J 2014; 105:911-8. [PMID: 23972843 DOI: 10.1016/j.bpj.2013.07.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 06/17/2013] [Accepted: 07/01/2013] [Indexed: 12/18/2022] Open
Abstract
The intercellular lipid matrix of the skin's stratum corneum serves to protect the body against desiccation and simultaneously limits the passage of drugs and other xenobiotics into the body. The matrix is made up of ceramides, free fatty acids, and cholesterol, which are organized as two coexisting crystalline lamellar phases. In studies reported here, we sought to use the technique of neutron diffraction, together with the device of isotopic (H/D) substitution, to determine the molecular architecture of the lamellar phase having a repeat distance of 53.9 ± 0.3 Å. Using hydrogenous samples as well as samples incorporating perdeuterated (C24:0) fatty acids and selectively deuterated cholesterol, the diffraction data obtained were used to construct neutron scattering length density profiles. By this means, the locations within the unit cell were determined for the cholesterol and fatty acids. The cholesterol headgroup was found to lie slightly inward from the unit cell boundary and the tail of the molecule located 6.2 ± 0.2 Å from the unit cell center. The fatty acid headgroups were located at the unit cell boundary with their acyl chains straddling the unit cell center. Based on these results, a molecular model is proposed for the arrangement of the lipids within the unit cell.
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Affiliation(s)
- E H Mojumdar
- Department of Drug Delivery Technology, University of Leiden, Leiden, the Netherlands
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31
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Dabkowska AP, Barlow DJ, Clifton LA, Hughes AV, Webster JRP, Green RJ, Quinn PJ, Lawrence MJ. Calcium-mediated binding of DNA to 1,2-distearoyl-sn-glycero-3-phosphocholine-containing mixed lipid monolayers. Soft Matter 2014; 10:1685-1695. [PMID: 24652078 DOI: 10.1039/c3sm52747f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The calcium-mediated interaction of DNA with monolayers of the non-toxic, zwitterionic phospholipid, 1,2-distearoyl-sn-glycero-3-phosphocholine when mixed with 50 mol% of a second lipid, either the zwitteronic 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine or neutral cholesterol was investigated using a combination of surface pressure-area isotherms, Brewster angle microscopy, external reflectance Fourier transform infrared spectroscopy and specular neutron reflectivity in combination with contrast variation. When calcium and DNA were both present in the aqueous subphase, changes were observed in the compression isotherms as well as the surface morphologies of the mixed lipid monolayers. In the presence of calcium and DNA, specular neutron reflectivity showed that directly underneath the head groups of the lipids comprising the monolayers, DNA occupied a layer comprising approximately 13 and 18% v/v DNA for the 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine and cholesterol-containing monolayers, respectively. The volume of the corresponding layer for 1,2-distearoyl-sn-glycero-3-phosphocholine only containing monolayers was ∼15% v/v DNA. Furthermore regardless of the presence and nature of the second lipid and the surface pressure of the monolayer, the specular neutron reflectivity experiments showed that the DNA-containing layer was 20-27 Å thick, suggesting the presence of a well-hydrated layer of double-stranded DNA. External reflectance Fourier transform infrared studies confirmed the presence of double stranded DNA, and indicated that the strands are in the B-form conformation. The results shed light on the interaction between lipids and nucleic acid cargo as well as the role of a second lipid in lipid-based carriers for drug delivery.
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Affiliation(s)
- Aleksandra P Dabkowska
- Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College London, 150 Stamford Street, London SE1 9NH, UK.
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32
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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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Welser K, Campbell F, Kudsiova L, Mohammadi A, Dawson N, Hart SL, Barlow DJ, Hailes HC, Lawrence MJ, Tabor AB. Gene Delivery Using Ternary Lipopolyplexes Incorporating Branched Cationic Peptides: The Role of Peptide Sequence and Branching. Mol Pharm 2012; 10:127-41. [DOI: 10.1021/mp300187t] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Katharina Welser
- Department of Chemistry, University
College London, Christopher Ingold Laboratories, 20 Gordon Street,
London WC1H 0AJ, U.K
| | - Frederick Campbell
- Department of Chemistry, University
College London, Christopher Ingold Laboratories, 20 Gordon Street,
London WC1H 0AJ, U.K
| | - Laila Kudsiova
- Institute
of Pharmaceutical
Science, King’s College London, Franklin-Wilkins Building,
150 Stamford Street, Waterloo Campus, London SE1 9NH, U.K
| | - Atefeh Mohammadi
- Department of Chemistry, University
College London, Christopher Ingold Laboratories, 20 Gordon Street,
London WC1H 0AJ, U.K
| | - Natalie Dawson
- Department of Chemistry, University
College London, Christopher Ingold Laboratories, 20 Gordon Street,
London WC1H 0AJ, U.K
| | - Stephen L. Hart
- Wolfson Centre for Gene Therapy
of Childhood Disease, UCL Institute of Child Health, 30 Guilford Street,
London WC1N 1EH, U.K
| | - David J. Barlow
- Institute
of Pharmaceutical
Science, King’s College London, Franklin-Wilkins Building,
150 Stamford Street, Waterloo Campus, London SE1 9NH, U.K
| | - Helen C. Hailes
- Department of Chemistry, University
College London, Christopher Ingold Laboratories, 20 Gordon Street,
London WC1H 0AJ, U.K
| | - M. Jayne Lawrence
- Institute
of Pharmaceutical
Science, King’s College London, Franklin-Wilkins Building,
150 Stamford Street, Waterloo Campus, London SE1 9NH, U.K
| | - Alethea B. Tabor
- Department of Chemistry, University
College London, Christopher Ingold Laboratories, 20 Gordon Street,
London WC1H 0AJ, U.K
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Barlow DJ, Buriani A, Ehrman T, Bosisio E, Eberini I, Hylands PJ. In-silico studies in Chinese herbal medicines' research: evaluation of in-silico methodologies and phytochemical data sources, and a review of research to date. J Ethnopharmacol 2012; 140:526-534. [PMID: 22326356 PMCID: PMC7126886 DOI: 10.1016/j.jep.2012.01.041] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 01/24/2012] [Accepted: 01/24/2012] [Indexed: 05/31/2023]
Abstract
The available databases that catalogue information on traditional Chinese medicines are reviewed in terms of their content and utility for in-silico research on Chinese herbal medicines, as too are the various protein database resources, and the software available for use in such studies. The software available for bioinformatics and 'omics studies of Chinese herbal medicines are summarised, and a critical evaluation given of the various in-silico methods applied in screening Chinese herbal medicines, including classification trees, neural networks, support vector machines, docking and inverse docking algorithms. Recommendations are made regarding any future in-silico studies of Chinese herbal medicines.
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Affiliation(s)
- D J Barlow
- Institute of Pharmaceutical Science, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, UK.
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35
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Swuec P, Barlow DJ. Prediction of inhibitory activities of Hsp90 inhibitors. Bioorg Med Chem 2012; 20:408-14. [DOI: 10.1016/j.bmc.2011.10.069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 10/21/2011] [Accepted: 10/24/2011] [Indexed: 10/15/2022]
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36
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Kudsiova L, Fridrich B, Ho J, Mustapa MFM, Campbell F, Welser K, Keppler M, Ng T, Barlow DJ, Tabor AB, Hailes HC, Lawrence MJ. Lipopolyplex Ternary Delivery Systems Incorporating C14 Glycerol-Based Lipids. Mol Pharm 2011; 8:1831-47. [DOI: 10.1021/mp2001796] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Laila Kudsiova
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, Waterloo Campus, London SE1 9NH, U.K
| | - Barbara Fridrich
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, Waterloo Campus, London SE1 9NH, U.K
| | - Jimmy Ho
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - M. Firouz Mohd Mustapa
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Frederick Campbell
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Katharina Welser
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Melanie Keppler
- Randall Division of Cell and Molecular Biophysics, King’s College London, Henriette Raphael Building, Guy's Campus, London SE1 1UL, U.K
| | - Tony Ng
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
- Randall Division of Cell and Molecular Biophysics, King’s College London, Henriette Raphael Building, Guy's Campus, London SE1 1UL, U.K
| | - David J. Barlow
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, Waterloo Campus, London SE1 9NH, U.K
| | - Alethea B. Tabor
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Helen C. Hailes
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - M. Jayne Lawrence
- Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, Waterloo Campus, London SE1 9NH, U.K
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37
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Dabkowska AP, Barlow DJ, Hughes AV, Campbell RA, Quinn PJ, Lawrence MJ. The effect of neutral helper lipids on the structure of cationic lipid monolayers. J R Soc Interface 2011; 9:548-61. [PMID: 21831895 DOI: 10.1098/rsif.2011.0356] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Successful drug delivery via lipid-based systems has often been aided by the incorporation of 'helper lipids'. While these neutral lipids enhance the effectiveness of cationic lipid-based delivery formulations, many questions remain about the nature of their beneficial effects. The structure of monolayers of the cationic lipid dimethyldioctadecylammonium bromide (DODAB) alone, and mixed with a neutral helper lipid, either diolelyphosphatidylethanolamine or cholesterol at a 1 : 1 molar ratio was investigated at the air-water interface using a combination of surface pressure-area isotherms, Brewster angle microscopy (BAM) and specular neutron reflectivity in combination with contrast variation. BAM studies showed that while pure DODAB and DODAB with cholesterol monolayers showed fairly homogeneous surfaces, except in the regions of phase transition, monolayers of DODAB with diolelyphosphatidylethanolamine were, in contrast, inhomogeneous exhibiting irregular bean-shaped domains throughout. Neutron reflectivity data showed that while the thickness of the DODAB monolayer increased from 17 to 24 Å as it was compressed from a surface pressure of 5-40 mN m(-1), the thickness of the helper lipid-containing monolayers, over the same range of surface pressures, was relatively invariant at between 25 and 27 Å. In addition, the monolayers containing diolelyphosphatidylethanolamine were found to be more heavily hydrated than the monolayers of cationic lipid, alone or in combination with cholesterol, with hydration levels of 18 molecules of water per molecule of lipid being recorded for the diolelyphosphatidylethanolamine-containing monolayers at a surface pressure of 30 mN m(-1) compared with only six and eight molecules of water per molecule of lipid for the pure DODAB monolayer and the cholesterol-containing DODAB monolayer, respectively.
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Affiliation(s)
- A P Dabkowska
- Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College London, 150 Stamford Street, London SE1 9NH, UK
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38
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Foglia F, Barlow DJ, Szoka FC, Huang Z, Rogers SE, Lawrence MJ. Structural studies of the monolayers and bilayers formed by a novel cholesterol-phospholipid chimera. Langmuir 2011; 27:8275-8281. [PMID: 21634402 DOI: 10.1021/la200739y] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Langmuir isotherm, neutron reflectivity, and small angle neutron scattering studies have been conducted to characterize the monolayers and vesicular bilayers formed by a novel chimeric phospholipid, ChemPPC, that incorporates a cholesteryl moeity and a C-16 aliphatic chain, each covalently linked via a glycerol backbone to phosphatidylcholine. The structures of the ChemPPC monolayers and bilayers are compared against those formed from pure dipalmitoylphoshatidylcholine (DPPC) and those formed from a 60:40 mol % mixture of DPPC and cholesterol. In accord with previous findings showing that very similar macroscopic properties were exhibited by ChemPPC and 60:40 mol % DPPC/cholesterol vesicles, it is found here that the chimeric lipid and lipid/sterol mixture have very similar monolayer structures (each having a monolayer thickness of ∼26 Å), and they also form vesicles with similar lamellar structure, each having a bilayer thickness of ∼50 Å and exhibiting a repeat spacing of ∼65 Å. The interfacial area of ChemPPC, however, is around 10 Å(2) greater than that of the combined DPPC/cholesterol unit in the mixed lipid monolayer (viz., 57 ± 1 vs 46 ± 1 Å(2), at 35 mN·m(-1)), and this difference in area is attributed to the succinyl linkage which joins the ChemPPC steroid and glyceryl moieties. The larger area of the ChemPPC is reflected in a slightly thicker monolayer solvent distribution width (9.5 vs 9 Å for the DPPC/cholesterol system) and by a marginal increase in the level of lipid headgroup hydration (16 vs 13 H(2)O per lipid, at 35 mN·m(-1)).
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Affiliation(s)
- F Foglia
- Pharmaceutical Science Division, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
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39
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Groen D, Gooris GS, Barlow DJ, Lawrence MJ, van Mechelen JB, Demé B, Bouwstra JA. Disposition of ceramide in model lipid membranes determined by neutron diffraction. Biophys J 2011; 100:1481-9. [PMID: 21402030 DOI: 10.1016/j.bpj.2011.02.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 02/01/2011] [Accepted: 02/01/2011] [Indexed: 10/18/2022] Open
Abstract
The lipid matrix present in the uppermost layer of the skin, the stratum corneum, plays a crucial role in the skin barrier function. The lipids are organized into two lamellar phases. To gain more insight into the molecular organization of one of these lamellar phases, we performed neutron diffraction studies. In the diffraction pattern, five diffraction orders were observed attributed to a lamellar phase with a repeat distance of 5.4 nm. Using contrast variation, the scattering length density profile could be calculated showing a typical bilayer arrangement. To obtain information on the arrangement of ceramides in the unit cell, a mixture that included a partly deuterated ceramide was also examined. The scattering length density profile of the 5.4-nm phase containing this deuterated ceramide demonstrated a symmetric arrangement of the ceramides with interdigitating acyl chains in the center of the unit cell.
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Affiliation(s)
- D Groen
- Leiden/Amsterdam Center for Drug Research, Department of Drug Delivery Technology, Gorlaeus Laboratories, University of Leiden, Leiden, The Netherlands
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40
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Affiliation(s)
- K S Wibley
- Department of Pharmacy, King's College London, Manresa Road, London, SW3 6LX
| | - D J Barlow
- Department of Pharmacy, King's College London, Manresa Road, London, SW3 6LX
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41
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van der Walle CF, Prodromou C, Barlow DJ. Cloning, expression and structure determination of the major extracellular domain of the PepT***1 oligopeptide transporter. J Pharm Pharmacol 2011. [DOI: 10.1111/j.2042-7158.1998.tb02434.x] [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] [Indexed: 11/29/2022]
Affiliation(s)
- C F van der Walle
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - C Prodromou
- Biochemistry Department, University College London, London WC1E 6BT
| | - D J Barlow
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
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42
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Richardson CJ, Barlow DJ. Use of Voronoi tessellation in confidence-assessed prediction of protein structural class. J Pharm Pharmacol 2011. [DOI: 10.1111/j.2042-7158.1998.tb02456.x] [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] [Indexed: 11/29/2022]
Affiliation(s)
- C J Richardson
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - D J Barlow
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
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43
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Affiliation(s)
- A M C Myles
- Dept. of Pharmacy, University of London, Manresa Rd, London, SW3 6LX
| | - D J Barlow
- Pharm. Dev., SmithKline Beecham, Welwyn Garden City, Herts, AL7 1EY
| | - G France
- Dept. of Pharmacy, University of London, Manresa Rd, London, SW3 6LX
| | - M J Lawrence
- Dept. of Pharmacy, University of London, Manresa Rd, London, SW3 6LX
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44
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Ma G, Barlow DJ, Lawrence MJ, Timmins P. Small angle neutron scattering studies of non-ionic surfactant vesicles. J Pharm Pharmacol 2011. [DOI: 10.1111/j.2042-7158.1998.tb02348.x] [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] [Indexed: 11/30/2022]
Affiliation(s)
- G Ma
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - D J Barlow
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - M J Lawrence
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - P Timmins
- Institut Laue-Langevin, Grenoble, France
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45
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Muslim AM, Lawrence MJ, Barlow DJ, Webster J, Penfold J. SURFISS—an interactive program for surfactant interfacial structure simulation. J Pharm Pharmacol 2011. [DOI: 10.1111/j.2042-7158.1998.tb02257.x] [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] [Indexed: 11/28/2022]
Affiliation(s)
- A-M Muslim
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - M J Lawrence
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - D J Barlow
- Department of Pharmacy, King’s College London, Manresa Road, London SW3 6LX
| | - J Webster
- ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX
| | - J Penfold
- ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX
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46
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Affiliation(s)
- SM Lawrence
- Department of Pharmacy, King's College London, Manresa Road, London SW3 6LX
| | - MJ Lawrence
- Department of Pharmacy, King's College London, Manresa Road, London SW3 6LX
| | - DJ Barlow
- Department of Pharmacy, King's College London, Manresa Road, London SW3 6LX
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47
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Callow P, Fragneto G, Cubitt R, Barlow DJ, Lawrence MJ. Interaction of cationic lipid/DNA complexes with model membranes as determined by neutron reflectivity. Langmuir 2009; 25:4181-4189. [PMID: 19714835 DOI: 10.1021/la802847h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Transfection of cells by DNA for the purposes of gene therapy can be effectively engineered through the use of cationic lipid/DNA "lipoplexes", although the transfection efficiency of these complexes is sensitive to the neutral "helper" lipid included. Here, neutron reflectivity has been used to investigate the role of the helper lipid present during the interaction of these lipoplexes with model membranes composed primarily of zwitterionic lipid 1,2-dimyristoylphosphatidylcholine (DMPC) together with 10 mol % 1,2-dipalmitoylphosphatidylserine (DPPS). Dimethyldioctadecylammonium bromide (DDAB) vesicles were formed with two different helper lipids, 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) and cholesterol, and complexed with a 1:1 charge ratio of DNA. The interaction of these complexes with the supported phospholipid bilayer was determined. DOPE-containing lipoplexes were found to interact faster with the model cell membrane than those containing cholesterol, and complexes containing either of the neutral helper lipids were found to interact faster than when DDAB alone was present. The interaction between the lipoplexes and the model membrane was characterized by an exchange of lipid between the membrane and the lipid/DNA aggregates in solution; the deposition of(additional) lipid on the surface of the model cell membrane was not apparent.
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Affiliation(s)
- P Callow
- Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France.
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48
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Talbot JP, Barlow DJ, Lawrence MJ, Timmins PA, Fragneto G. Interaction of cationic lipoplexes with floating bilayers at the solid-liquid interface. Langmuir 2009; 25:4168-4180. [PMID: 19714898 DOI: 10.1021/la802844f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [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
Neutron reflection has been used to study the interaction of cationic lipoplexes with different model membrane systems. The model membranes used are prepared as "floating" phospholipid bilayers deposited at a silicon/water interface and separated from the solid substrate either by an adsorbed phospholipid bilayer, polymer cushions composed of polyethylene glycol lipids, or a lipid monolayer adsorbed onto a chemically grafted hydrocarbon layer. The cationic lipoplexes studied are those formed by the complexation of calf thymus DNA with dimethyl-dioctadecylammonium bromide (DDAB), with either cholesterol or dioleoyl-L-alpha-phosphatidylethanolamine (DOPE) incorporated as "helper" lipid. The cationic lipoplexes are found to destroy three of the four types of (negatively charged) floating bilayers, with the rate of destruction dependent on the nature of the layer separating the floating bilayer from the silicon substrate. The only bilayers to remain intact after exposure to the lipoplexes were those fabricated above the chemically grafted (octadecyl) hydrocarbon layer. This supports the hypothesis that the high negative charge density of the SiO2 layer on the silicon surface may influence, by way of electrostatic interaction with the cationic lipid, the interaction of the lipoplexes with the model bilayer. It is concluded that the floating bilayer supported on a chemically grafted hydrocarbon layer lends itself perfectly to the study of lipoplex-membrane interactions and, with sufficient exposure time, would allow a detailed characterization of the structures formed at the membrane interface during the interaction.
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Affiliation(s)
- Jonathan P Talbot
- Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, F-38042 Grenoble, France
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49
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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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50
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Chen X, Jayne Lawrence M, Barlow DJ, Morris RJ, Heenan RK, Quinn PJ. The structure of detergent-resistant membrane vesicles from rat brain cells. Biochim Biophys Acta 2008; 1788:477-83. [PMID: 19118517 DOI: 10.1016/j.bbamem.2008.11.023] [Citation(s) in RCA: 12] [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] [Received: 07/17/2008] [Revised: 11/20/2008] [Accepted: 11/25/2008] [Indexed: 11/19/2022]
Abstract
The size and the bilayer thickness of detergent-resistant membranes isolated from rat brain neuronal membranes using Triton X-100 or Brij 96 in buffers with or without the cations, K+/Mg2+ at a temperature of either 4 degrees C or 37 degrees C were determined by dynamic light scattering and small-angle neutron scattering. Regardless of the precise conditions used, isolated membrane preparations consisted of vesicles of approximately 100 to 200 nm diameter as determined by dynamic light scattering methods, equating to an area of the lipid based membrane microdomain size of 200 to 400 nm diameter. By means of small angle neutron scattering it was established that the average thickness of the bilayers of the complete population of detergent-resistant membranes was similar to that of the parental membrane at between 4.6 and 5.0 nm. Detergent-resistant membranes prepared using buffers containing K+/Mg2+ uniquely formed unilamellar vesicles while membranes prepared in the absence of K+/Mg2+ formed a mixture of uni- and oligolamellar structures indicating that the arrangement of the membrane differs from that observed in the presence of cations. Furthermore, the detergent-resistant membranes prepared at 37 degrees C were slightly thicker than those prepared at 4 degrees C, consistent with the presence of a greater proportion of lipids with longer, more saturated fatty acid chains associated with the Lo (liquid-ordered) phase. It was concluded that the preparation of detergent-resistant membranes at 37 degrees C using buffer containing cations abundant in the cytoplasm might more accurately reflect the composition of lipid rafts present in the plasma membrane under physiological conditions.
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Affiliation(s)
- Xi Chen
- Pharmaceutical Science Division, King's College London, 150 Stamford Street, London SE1 9NH, UK
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