| 1. |
- Hellinen, Laura, et al.
(författare)
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Inhibition of prolyl oligopeptidase : A promising pathway to prevent the progression of age-related macular degeneration
- 2022
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Ingår i: Biomedicine and Pharmacotherapy. - : Elsevier. - 0753-3322 .- 1950-6007. ; 146
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Tidskriftsartikel (refereegranskat)abstract
- Dry age-related macular degeneration (AMD) is a currently untreatable vision threatening disease. Impaired proteasomal clearance and autophagy in the retinal pigment epithelium (RPE) and subsequent photoreceptor damage are connected with dry AMD, but detailed pathophysiology is still unclear. In this paper, we discover inhibition of cytosolic protease, prolyl oligopeptidase (PREP), as a potential pathway to treat dry AMD. We showed that PREP inhibitor exposure induced autophagy in the RPE cells, shown by increased LC3-II levels and decreased p62 levels. PREP inhibitor treatment increased total levels of autophagic vacuoles in the RPE cells. Global proteomics was used to examine the phenotype of a commonly used cell model displaying AMD characteristics, oxidative stress and altered protein metabolism, in vitro. These RPE cells displayed induced protein aggregation and clear alterations in macromolecule metabolism, confirming the relevance of the cell model. Differences in intracellular target engagement of PREP inhibitors were observed with cellular thermal shift assay (CETSA). These differences were explained by intracellular drug exposure (the unbound cellular partition coefficient, Kpuu). Importantly, our data is in line with previous observations regarding the discrepancy between PREP's cleaving activity and outcomes in autophagy. This highlights the need to further explore PREP's role in autophagy so that more effective compounds can be designed to battle diseases in which autophagy induction is needed. The present work is the first report investigating the PREP pathway in the RPE and we predict that the PREP inhibitors can be further optimized for treatment of dry AMD.
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| 2. |
- Issa, Mohamed Mahmoud, 1974-
(författare)
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Linear and Branched Chitosan Oligomers as Delivery Systems for pDNA and siRNA In Vitro and In Vivo
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, chitosan, a biocompatible polysaccharide that has been approved as a food additive was selected as a platform for the development of safe, efficient non-viral gene delivery systems to mammalian cells. Previously, chitosan-based gene formulations had been generally associated with high molecular weight chitosans, which were poorly characterised in terms of molecular weight distribution and degree of acetylation. Therefore, in order to improve the properties of chitosan-based gene formulations, the research associated with this thesis focused on establishing the structure-property relationships of well-defined, low molecular weight chitosans (chitosan oligomers) as delivery systems for nucleic acids (pDNA and siRNA) in vitro and after lung administration in vivo. pDNA dissociated more easily from chitosan oligomers than from conventional high molecular weight chitosans, resulting in a faster onset and higher levels of in vivo gene expression, comparable to those mediated by polyethyleneimine (PEI), one of the most efficient non-viral delivery systems. Coupling of a trisaccharide branch to the chitosan oligomers so as to target extracellular lectins resulted in a significant improvement in transfection efficiency because of enhanced cellular uptake and colloidal stability. In contrast to pDNA, longer linear chitosan oligomers were required to form physically-stable nanoparticles with siRNA that mediated efficient, sustained gene silencing in vitro. Finally, the use of an optimised catheter device for the nebulisation of small volumes of pDNA formulations resulted in improved dose precision and lung distribution in vivo compared with conventional intratracheal instillation. In conclusion, chitosan oligomers are interesting and viable alternatives to other non-viral gene delivery systems.
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| 3. |
- Linnankoski, Johanna, et al.
(författare)
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Paracellular porosity and pore size of the human intestinal epithelium in tissue and cell culture models
- 2010
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 99:4, s. 2166-2175
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Tidskriftsartikel (refereegranskat)abstract
- The paracellular space defines the passive permeation of hydrophilic compounds in epithelia. The goal of this study was to characterise the paracellular permeation pathway in the human intestinal wall and differentiated epithelial cell models (MDCKII, Caco-2 and 2/4/A1). The permeabilities of hydrophilic polyethylene glycols (PEG) were investigated in diffusion chambers, and mass spectrometry was used to obtain accurate concentrations for each PEG molecule. The paracellular porosity and the size of the pores in the membranes were estimated from the PEG permeability data using an effusion-based approach. The porosities were found to be low (fraction 10−7–10−5 of the epithelial surface) in all investigated membranes. Two different pore sizes (radii 5–6 and >10 Å) were detected in the human intestinal epithelium and the Caco-2 and MDCKII cells, while only one (about 15 Å) in the 2/4/A1 monolayer. The paracellular porosities of the human small intestine and 2/4/A1 monolayers were larger (>10−7) than that of the MDCKII and Caco-2 cells (<10−7). We report for the first time the quantitative values describing both porosity and pore size of the paracellular space in the human intestine. The cell models deviate from the small intestine either with respect to porosity (Caco-2, MDCKII) or pore size distribution (2/4/A1).
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| 4. |
- Merclin, Nadia, 1971-
(författare)
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Electrochemical Methods for Drug Characterisation and Transdermal Delivery : Capillary Zone Electrophoresis, Conductometry, and Iontophoresis
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the development and utilisation of techniques for characterisation and transdermal delivery of various systems for pharmaceutical applications.The degree of dissociation of drug molecules and the mobilities of the different species formed are essential factors affecting the rate of drug delivery by iontophoresis. Hence, determination of drug mobility parameters and equilibrium constants are important for the development of iontophoretic systems. With capillary zone electrophoresis using a partial filling technique and methyl-β-cyclodextrin as chiral selector, the enantiomers of orciprenaline were separated. The association constants between the enantiomers of the drug and the selector were also evaluated. Precision conductometry studies were performed for the hydrochloride salts of lidocaine and 5-aminolevulinic acid in aqueous propylene glycol and water as media, respectively.Iontophoresis is a technique for drug delivery where charged molecules are transported into and through skin by application of a weak direct electrical current. The drugs 5-aminolevulinic acid and its methyl ester were used as model compounds and incorporated in two different drug delivery vehicles, a sponge phase and carbopol gel. The bicontinuous structure of the sponge phase, constituted of monoolein and a mixture of propylene glycol and water, makes it interesting for use in iontophoretic delivery, since ions can move more or less freely in the aqueous as well as in the lipid domains. Furthermore, all three components are known for their penetration enhancing abilities. Hydrogels like carbopol gels are interesting media with respect to iontophoretic studies, since devices for iontophoresis often utilize hydrogels as contact interfaces between the skin and the electrodes. The results indicate that the transport achieved iontophoretically using the gel (1 % active substance) was comparable with the passive delivery of clinically used formulations (16 % - 20 % active substance).
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| 5. |
- Nilsson, Christa, et al.
(författare)
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Characterization of Oil-Free and Oil-Loaded Liquid-Crystalline Particles Stabilized by Negatively Charged Stabilizer Citrem
- 2012
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:32, s. 11755-11766
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Tidskriftsartikel (refereegranskat)abstract
- The present study was designed to evaluate the effect of the negatively charged food-grade emulsifier citrem on the internal nanostructures of oil-free and oil-loaded aqueous dispersions of phytantriol (PHYT) and glyceryl monooleate (GMO). To our knowledge, this is the first report in the literature on the utilization of this charged stabilizing agent in the formation of aqueous dispersions consisting of well-ordered interiors (either inverted-type hexagonal (H2) phases or inverted-type microemulsion systems). Synchrotron small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) were used to characterize the dispersed and the corresponding nondispersed phases of inverted-type nonlamellar liquid-crystalline phases and microemulsions. The results suggest a transition between different internal nanostructures of the aqueous dispersions after the addition of the stabilizer. In addition to the main function of citrem as a stabilizer that adheres to the surface of the dispersed particles, it has a significant impact on the internal nanostructures, which is governed by the following factors: (1) its penetration between the hydrophobic tails of the lipid molecules and (2) its degree of incorporation into the lipid–water interfacial area. In the presence of citrem, the formation of aqueous dispersions with functionalized hydrophilic domains by the enlargement of the hydrophilic nanochannels of the internal H2 phase in hexosomes and the hydrophilic core of the L2 phase in emulsified microemulsions (EMEs) could be particularly attractive for solubilizing and controlling the release of positively charged drugs.
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