| 1. |
- Dew, Noel, 1980-, et al.
(författare)
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Gel formulations containing catanionic vesicles composed of alprenolol and SDS : effects of drug release and skin penetration on aggregate structure
- 2012
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 89, s. 53-60
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Tidskriftsartikel (refereegranskat)abstract
- To fully utilize the extended contact time of gel formulations a novel formulation with drug containing catanionic aggregates offering prolonged drug release and skin penetration were investigated. This study aimed to further explore the drug release process from catanionic vesicles in gels. Catanionic vesicles were formed from alprenolol and sodium dodecyl sulphate. Physical gels composed of catanionic vesicles and a SoftCAT polymer were used as well as covalent Carbopol gels. Drug release was measured in vitro using a modified USP paddle method and the skin penetration was studied using dermatomized pig ear skin mounted in horizontal Ussing chambers. The aggregate structure was visualized with cryo-TEM during the drug release and skin penetration process. The study results show that catanionic vesicles are present in the formulations throughout the drug release process and during the clinically relevant skin application time. Hence, the decreased skin penetration rate stems from the prolonged release of drug substance from the gels. The rheological investigation shows that the gel structure of the physically cross-linked gels is maintained even as the drug substance is released and the gel volume is decreased.These findings indicate that the applicability of formulations like these is a future possibility.
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| 2. |
- Aad, G., et al.
(författare)
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- 2012
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Aad, G., et al.
(författare)
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- 2012
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Ingår i: Nuclear Physics, Section B. - : Elsevier BV. - 0550-3213 .- 1873-1562. ; 864:3, s. 341-381
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Aad, G., et al.
(författare)
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- 2013
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Tidskriftsartikel (refereegranskat)
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| 5. |
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| 7. |
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| 8. |
- Agmo Hernández, Víctor, et al.
(författare)
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Intrinsic Heterogeneity in Liposome Suspensions Caused by the Dynamic Spontaneous Formation of Hydrophobic Active Sites in Lipid Membranes
- 2011
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:8, s. 4873-4883
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Tidskriftsartikel (refereegranskat)abstract
- The spontaneous, dynamic formation of hydrophobic active sites in lipid bilayer membranes is studied and characterized. It is shown that the rates of formation and consumption of these active sites control at least two important properties of liposomes: their affinity for hydrophobic surfaces and the rate by which they spontaneously release encapsulated molecules. The adhesion and spreading of liposomes onto hydrophobic polystyrene nanoparticles and the spontaneous leakage of an encapsulated fluorescent dye were monitored for different liposome compositions employing Cryo-TEM, DLS, and fluorescence measurements. It was observed that an apparently homogeneous, monodisperse liposome suspension behaves as if composed by two different populations: a fast leaking population that presents affinity for the hydrophobic substrate employed, and a slow leaking population that does not attach immediately to it. The results reported here suggest that the proportion of liposomes in each population changes over time until a dynamic equilibrium is reached. It is shown that this phenomenom can lead to irreproducibility in, for example, spontaneous leakage experiments, as extruded liposomes leak much faster just after preparation than 24 h afterward. Our findings account for discrepancies in several experimental results reported in the literature. To our knowledge, this is the first systematic study addressing the issue of an existing intrinsic heterogeneity of liposome suspensions.
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| 9. |
- Agmo Hernández, Víctor, et al.
(författare)
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Label-Free Characterization of Peptide-Lipid Interactions Using Immobilized Lipodisks
- 2013
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 85:15, s. 7377-7384
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Tidskriftsartikel (refereegranskat)abstract
- Lipodisks, planar lipid bilayer structures stabilized by PEG-ylated lipids, were in the present study covalently bound and immobilized onto sensors for quartz crystal microbalance with dissipation monitoring (QCM-D) studies. It is shown that the modified sensors can be used to characterize the interaction of lipodisks with α-helical amphiphilic peptides with an accuracy similar to that obtained with well established fluorimetric approximations. The method presented has the great advantage that it can be used with peptides in their native form even if no fluorescent residues are present. The potential of the method is illustrated by determining the parameters describing the association of melittin, mastoparan X, and mastoparan with immobilized lipodisks. Both thermodynamic and kinetic analyses are possible. The presented method constitutes a useful tool for fundamental studies of peptide–membrane interactions and can also be applied to optimize the design of lipodisks, for example, for sustained release of antimicrobial peptides in therapeutic applications.
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| 10. |
- Ariöz, Candan, 1983-, et al.
(författare)
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Heterologous overexpression of a monotopic glucosyltransferase (MGS) induces fatty acid remodeling in Escherichia coli membranes :
- 2014
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736 .- 1879-2642. ; 1838:7, s. 1862-1870
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Tidskriftsartikel (refereegranskat)abstract
- The membrane protein monoglucosyldiacylglycerol synthase (MGS) from Acholeplasma laidlawii is responsible for the creation of intracellular membranes when overexpressed in Escherichia coli (E. coli). The present study investigates time dependent changes in composition and properties of E. coli membranes during 22 h of MGS induction. The lipid/protein ratio increased by 38% in MGS-expressing cells compared to control cells. Time-dependent screening of lipids during this period indicated differences in fatty acid modeling. (1) Unsaturation levels remained constant for MGS cells (~ 62%) but significantly decreased in control cells (from 61% to 36%). (2) Cyclopropanated fatty acid content was lower in MGS producing cells while control cells had an increased cyclopropanation activity. Among all lipids, phosphatidylethanolamine (PE) was detected to be the most affected species in terms of cyclopropanation. Higher levels of unsaturation, lowered cyclopropanation levels and decreased transcription of the gene for cyclopropane fatty acid synthase (CFA) all indicate the tendency of the MGS protein to force E. coli membranes to alter its usual fatty acid composition.
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