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- Axelsson, Viktoria, 1973-
(författare)
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Evaluation of neurotoxic properties of gliotoxin
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The occurrence of mould in food and animal feed is a severe problem due to the secondary metabolites, called mycotoxins, which can possess toxic activity. Aspergillus fumigatus is a common fungus found in improperly stored animal feed and the abundance of spores of the fungus is frequently spread into the air. Gliotoxin has been identified as one of the most toxic second metabolites produced by A. fumigatus. Although A. fumigatus is known to produce mycotoxins that induce neurological syndromes, the neurotoxic properties of gliotoxin have not previously been studied. In this thesis a neurotoxic activity of gliotoxin was demonstrated by using differentiated human neuroblastoma SH-SY5Y cells as a surrogate for the nervous system. The major findings were as follows: i. Gliotoxin is highly toxic to SH-SY5Y cells and there is a correlation between the toxicity and the cellular redox status. ii. Gliotoxin reduces the number of neurites, but does not affect the cell bodies morphologically, at non-cytotoxic concentrations. This indicates that the toxin may induce peripheral axonopathy in vivo. iii. The intracellular free Ca2+ concentration is increased after exposure to gliotoxin, an effect that is the most ubiquitous feature of neuronal cell death. Simultaneously, calpains and caspases, proteases known to be involved in neuronal death and axonal degeneration, are activated. iv. The observed irreversible neurite degenerative effects of gliotoxin are mainly dependent on caspase activation, whereas calpains are involved in the gliotoxin-induced cytotoxicity. v. Gliotoxin induces a decreased rate of protein synthesis at non-cytotoxic concentration, which may contribute to the degeneration of neurites. vi. We did also succeed in developing an in vitro method for determination of toxic activity in animal feed. This study was done in collaboration with National Veterinary Institute (SVA) in Uppsala, and the method is today established and in use at Department of Animal Feed, SVA.
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| 2. |
- EL Andaloussi-Lilja, Johanna, 1980-
(författare)
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Activation and Regulation of TRPV1 : Studies in Recombinant Human Neuroblastoma TRPV1-SHSY5Y Cells
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- TRPV1 is a transmembrane non-selective cation channel with preference for Ca2+. The receptor is primarily localised on dorsal root ganglion neurons and is activated by numerous endogenous and exogenous potentially irritating ligands eliciting pain. The TRPV1 expression and activity are regulated by several neurotrophic agents and inflammatory mediators via activation of phosphorylation cascades. In this thesis a stably TRPV1-expressing cell clone of the human neuroblastoma cell line SHSY5Y was established with the purpose to study regulation of TRPV1 through a straightforward and reproducible approach. In paper I it is reported that the neurotrophic factors insulin, and IGF-1 up-regulate TRPV1 in the TRPV1-SHSY5Y cells. Additionally, the involved signalling pathways are suggested. This is of interest because both TRPV1 activity and expression is altered in diabetic patients with painful neuropathies, and so is insulin and IGF-1 signalling. Results from paper II show that the neuronally differentiating morphogen retinoic acid (RA) increases TRPV1 protein levels and TRPV1-mediated Ca2+ influxes. Furthermore, the basal Ca2+ level is increased after RA treatment in TRPV1-SHSY5Y cells but not in native SHSY5Y cells. The TRPV1-SHSY5Y cells also develop into a more mature neuronal phenotype than the native SHSY5Y cells after six days of RA-induced differentiation. Hence, TRPV1 might be involved in neurogenesis. In paper III-IV it is concluded that the TRPV1-SHSY5Y cells can be used in a semi-high throughput screening (HTS)-mode to adress TRPV1-mediated Ca2+ influxes. In this assay it is shown that anionic linear aliphatic surfactants might be potent ligands of TRPV1. As a concluding remark, the TRPV1–SHSY5Y cells can be utilised to assess activation and regulation of TRPV1 in an easy-to-use and robust model system.
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