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| 2. |
- Cohen, Samuel I.A., et al.
(författare)
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Distinct thermodynamic signatures of oligomer generation in the aggregation of the amyloid-β peptide
- 2018
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Ingår i: Nature Chemistry. - : Springer Science and Business Media LLC. - 1755-4330 .- 1755-4349. ; 10:5, s. 523-531
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Tidskriftsartikel (refereegranskat)abstract
- Mapping free-energy landscapes has proved to be a powerful tool for studying reaction mechanisms. Many complex biomolecular assembly processes, however, have remained challenging to access using this approach, including the aggregation of peptides and proteins into amyloid fibrils implicated in a range of disorders. Here, we generalize the strategy used to probe free-energy landscapes in protein folding to determine the activation energies and entropies that characterize each of the molecular steps in the aggregation of the amyloid-β peptide (Aβ42), which is associated with Alzheimer's disease. Our results reveal that interactions between monomeric Aβ42 and amyloid fibrils during fibril-dependent secondary nucleation fundamentally reverse the thermodynamic signature of this process relative to primary nucleation, even though both processes generate aggregates from soluble peptides. By mapping the energetic and entropic contributions along the reaction trajectories, we show that the catalytic efficiency of Aβ42 fibril surfaces results from the enthalpic stabilization of adsorbing peptides in conformations amenable to nucleation, resulting in a dramatic lowering of the activation energy for nucleation.
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| 4. |
- Niemelä, E., et al.
(författare)
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Nanoparticles carrying fingolimod and methotrexate enables targeted induction of apoptosis and immobilization of invasive thyroid cancer
- 2020
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : ELSEVIER. - 0939-6411 .- 1873-3441. ; 148, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Metastatic tumors are the main cause of cancer-related death, as the invading cancer cells disrupt normal functions of distant organs and are nearly impossible to eradicate by traditional cancer therapeutics. This is of special concern when the cancer has created multiple metastases and extensive surgery would be too dangerous to execute. Therefore, combination chemotherapy is often the selected treatment form. However, drug cocktails often have severe adverse effects on healthy cells, whereby the development of targeted drug delivery could minimize side-effects of drugs and increase the efficacy of the combination therapy. In this study, we utilized the folate antagonist methotrexate (MTX) as targeting ligand conjugated onto mesoporous silica nanoparticles (MSNs) for selective eradication of folate receptor-expressing invasive thyroid cancer cells. The MSNs was subsequently loaded with the drug fingolimod (FTY720), which has previously been shown to efficiently inhibit proliferation and invasion of aggressive thyroid cancer cells. To assess the efficiency of our carrier system, comprehensive in vitro methods were employed; including flow cytometry, confocal microscopy, viability assays, invasion assay, and label-free imaging techniques. The in vitro results show that MTX-conjugated and FTY720-loaded MSNs potently attenuated both the proliferation and invasion of the cancerous thyroid cells while keeping the off-target effects in normal thyroid cells reasonably low. For a more physiologically relevant in vivo approach we utilized the chick chorioallantoic membrane (CAM) assay, showing decreased invasive behavior of the thyroid derived xenografts and an increased necrotic phenotype compared to tumors that received the free drug cocktail. Thus, the developed multidrug-loaded MSNs effectively induced apoptosis and immobilization of invasive thyroid cancer cells, and could potentially be used as a carrier system for targeted drug delivery for the treatment of diverse forms of aggressive cancers that expresses folate receptors.
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| 6. |
- Rendell, M, et al.
(författare)
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Relationship between abdominal fat compartments and glucose and lipid metabolism in early postmenopausal women
- 2001
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - 1945-7197. ; 86:2, s. 744-749
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Tidskriftsartikel (refereegranskat)abstract
- The relationships between abdominal and pelvic fat compartments and glucose and lipid metabolism were investigated in early postmenopausal women. Fifty-five healthy, postmenopausal women aged 52-53 yr participated in the study. Fat distribution (intra-abdominal and sc abdominal fat, and intrapelvic and sc pelvic fat) was estimated by computed tomography. Insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp. In a multiple regression analysis, the size of the intra-abdominal fat compartment was the only significant predictor of insulin sensitivity (r(2) = 24%; P = 0.0002). Plasma triglycerides were closely related to the size of the intra-abdominal fat compartment (r(2) = 26%; P < 0.0001), whereas plasma free fatty acid concentrations only correlated to the size of the sc abdominal fat compartment (r(2) = 18.5%, P = 0.001). In early postmenopausal women the amount of the intra-abdominal fat strongly influences insulin sensitivity and plasma triglyceride levels, whereas plasma free fatty acids are closely related to the amount of the sc abdominal fat. Accordingly, from a metabolic standpoint it seems most essential to reduce intra-abdominal fat in postmenopausal women.
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| 8. |
- Törnquist, Mattias, et al.
(författare)
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Secondary nucleation in amyloid formation
- 2018
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 54:63, s. 8667-8684
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Tidskriftsartikel (refereegranskat)abstract
- Nucleation of new peptide and protein aggregates on the surfaces of amyloid fibrils of the same peptide or protein has emerged in the past two decades as a major pathway for both the generation of molecular species responsible for cellular toxicity and for the autocatalytic proliferation of peptide and protein aggregates. A key question in current research is the molecular mechanism and driving forces governing such processes, known as secondary nucleation. In this context, the analogies with other self-assembling systems for which monomer-dependent secondary nucleation has been studied for more than a century provide a valuable source of inspiration. Here, we present a short overview of this background and then review recent results regarding secondary nucleation of amyloid-forming peptides and proteins, focusing in particular on the amyloid β peptide (Aβ) from Alzheimer's disease, with some examples regarding α-synuclein from Parkinson's disease. Monomer-dependent secondary nucleation of Aβ was discovered using a combination of kinetic experiments, global analysis, seeding experiments and selective isotope-enrichment, which pinpoint the monomer as the origin of new aggregates in a fibril-catalyzed reaction. Insights into driving forces are gained from variations of solution conditions, temperature and peptide sequence. Selective inhibition of secondary nucleation is explored as an effective means to limit oligomer production and toxicity. We also review experiments aimed at finding interaction partners of oligomers generated by secondary nucleation in an ongoing aggregation process. At the end of this feature article we bring forward outstanding questions and testable mechanistic hypotheses regarding monomer-dependent secondary nucleation in amyloid formation.
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| 9. |
- Westerlind, Ulrika, et al.
(författare)
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Ligands of the asialoglycoprotein receptor for targeted gene delivery, part 1: Synthesis of and binding studies with biotinylated cluster glycosides containing N-acetylgalactosamine.
- 2004
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Ingår i: Glycoconjugate journal. - : Springer. - 0282-0080 .- 1573-4986. ; 21:5, s. 227-41
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Tidskriftsartikel (refereegranskat)abstract
- In order to develop the non-viral Bioplex vector system for targeted delivery of genes to hepatocytes, we have evaluated the structure-function relationship for a number of synthetic ligands designed for specific interaction with the hepatic lectin ASGPr. Biotinylated ligand derivatives containing two, three or six beta-linked N-acetylgalactosamine (GalNAc) residues were synthesized, bound to fluorescent-labeled streptavidin and tested for binding and uptake to HepG2 cells using flow cytometry analysis (FACS). Uptake efficiency increased with number of displayed GalNAc units per ligand, in a receptor dependent manner. Thus, a derivative displaying six GalNAc units showed the highest uptake efficacy both in terms of number of internalizing cells and increased amount of material taken up per each cell. However, this higher efficiency was shown to be due not so much to higher number of sugar units, but to higher accessibility of the sugar units for interaction with the receptor (longer spacer). Improving the flexibility and accessibility of a trimeric GalNAc ligand through use of a longer spacer markedly influenced the uptake efficiency, while increasing the number of GalNAc units per ligand above three only provided a minor contribution to the overall affinity. We hereby report the details of the chemical synthesis of the ligands and the structure-function studies in vitro.
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