| 1. |
- Mundt-Petersen, Ulrika, et al.
(författare)
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Caspase inhibition increases embryonic striatal graft survival
- 2000
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 164:1, s. 112-120
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Tidskriftsartikel (refereegranskat)abstract
- In transplants of embryonic striatal cells placed into the excitotoxically lesioned rat striatum (a model of Huntington's disease), as many as 60 to 90% of the grafted cells are believed to die. Caspase activation is part of a cascade of events that can lead to apoptosis. We investigated the effect of the caspase inhibitor acetyl-tyrosinyl-valyl-alanyl-aspartyl-chloromethylketone (Ac-YVAD-cmk) on grafted embryonic striatal cells in the excitotoxically lesioned or intact rat striatum. Female Sprague–Dawley rats were subjected to unilateral intrastriatal injection of quinolinic acid. After 10 days, rats received bilateral intrastriatal grafts from embryonic day 14 rat lateral ganglionic eminence. Rats were divided into the following groups: Ac-YVAD-cmk, pretreatment of the graft tissue with the caspase inhibitor (500 μM); and control, untreated control grafts. Rats were perfused 10 days or 5 weeks postgrafting. Brain sections were processed immunohistochemically using an antibody against the striatal neuron marker dopamine- and adenosine 3′,5′-monophosphate-regulated phosphoprotein with a molecular weight of 32 kDa (DARPP-32). Adjacent sections were stained for acetylcholinesterase/cresyl violet cytochemistry and Fluoro-Jade cytochemistry, a marker for degenerating neurons. Total graft volume, P-zone volume, total number of neuron-like cells, and number of DARPP-32-positive cells were increased, compared to control, in the group receiving Ac-YVAD-cmk-treated graft tissue. Moreover, transplants injected into the intact striatum were found to be significantly smaller compared to transplants placed into the excitotoxically lesioned striatum. The Fluoro-Jade staining revealed ongoing cell death in transplants 10 days after intrastriatal implantation and that cell death was significantly reduced 5 weeks after grafting.
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| 2. |
- Brundin, Patrik, et al.
(författare)
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Improving the survival of grafted dopaminergic neurons: a review over current approaches
- 2000
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Ingår i: Cell Transplantation. - 1555-3892. ; 9:2, s. 179-195
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Tidskriftsartikel (refereegranskat)abstract
- Neural transplantation is developing into a therapeutic alternative in Parkinson's disease. A major limiting factor is that only 3-20% of grafted dopamine neurons survive the procedure. Recent advances regarding how and when the neurons die indicate that events preceding actual tissue implantation and during the first week thereafter are crucial, and that apoptosis plays a pivotal role. Triggers that may initiate neuronal death in grafts include donor tissue hypoxia and hypoglycemia, mechanical trauma, free radicals, growth factor deprivation, and excessive extracellular concentrations of excitatory amino acids in the host brain. Four distinct phases during grafting that can involve cell death have been identified: retrieval of the embryo; dissection and preparation of the donor tissue; implantation procedure followed by the immediate period after graft injection; and later stages of graft maturation. During these phases, cell death processes involving free radicals and caspase activation (leading to apoptosis) may be triggered, possibly involving an increase in intracellular calcium. We review different approaches that reduce cell death and increase survival of grafted neurons, typically by a factor of 2-4. For example, changes in transplantation procedure such as improved media and implantation technique can be beneficial. Calcium channel antagonists such as nimodipine and flunarizine improve nigral graft survival. Agents that counteract oxidative stress and its consequences, such as superoxide dismutase overexpression, and lazaroids can significantly increase the survival of transplanted dopamine neurons. Also, the inhibition of apoptosis by a caspase inhibitor has marked positive effects. Finally, basic fibroblast growth factor and members of the transforming growth factor-beta superfamily, such as glial cell line-derived neurotrophic factor, significantly improve the outcome of nigral transplants. These recent advances provide hope for improved survival of transplanted neurons in patients with Parkinson's disease, reducing the need for human embryonic donor tissue and increasing the likelihood of a successful outcome.
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| 3. |
- Gil, Joana, et al.
(författare)
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Asialoerythropoetin is not effective in the R6/2 line of Huntington's disease mice
- 2004
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Ingår i: BMC Neuroscience. - : Springer Science and Business Media LLC. - 1471-2202. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Background: Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by an expanded CAG repeat in the HD gene. Both excitotoxicity and oxidative stress have been proposed to play important roles in the pathogenesis of HD. Since no effective treatment is available, this study was designed to explore the therapeutic potential of erythropoietin (EPO), a cytokine that has been found to prevent excitotoxicity, and to promote neurogenesis. To avoid the side effects of a raised hematocrit, we used asialoerythropoietin (asialoEPO), a neuroprotective variant of EPO that lacks erythropoietic effects in mice. R6/2 transgenic HD mice were treated with this cytokine from five to twelve weeks of age. Results: We provide new evidence that cell proliferation in the dentate gyrus of the R6/2 hippocampus is reduced by 50% compared to wild-type littermate controls. However, we found that the asialoEPO treatment did not affect the progression of motor symptoms, weight loss or the neuropathological changes. Furthermore, cell proliferation was not enhanced. Conclusions: We conclude that the chosen protocol of asialoEPO treatment is ineffective in the R6/2 model of HD. We suggest that reduced hippocampal cell proliferation may be an important and novel neuropathological feature in R6 HD mice that could be assessed when evaluating potential therapies.
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| 4. |
- Gisselsson Nord, David, et al.
(författare)
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Telomere dysfunction triggers extensive DNA fragmentation and evolution of complex chromosome abnormalities in human malignant tumors
- 2001
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 98:22, s. 12683-12688
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Tidskriftsartikel (refereegranskat)abstract
- Although mechanisms for chromosomal instability in tumors have been described in animal and in vitro models, little is known about these processes in man. To explore cytogenetic evolution in human tumors, chromosomal breakpoint profiles were constructed for 102 pancreatic carcinomas and 140 osteosarcomas, two tumor types characterized by extensive genomic instability. Cases with few chromosomal alterations showed a preferential clustering of breakpoints to the terminal bands, whereas tumors with many changes showed primarily interstitial and centromeric breakpoints. The terminal breakpoint frequency was negatively correlated to telomeric TTAGGG repeat length, and fluorescence in situ hybridization with telomeric TTAGGG probes consistently indicated shortened telomeres and >10% of chromosome ends lacking telomeric signals. Because telomeric dysfunction may lead to formation of unstable ring and dicentric chromosomes, mitotic figures were also evaluated. Anaphase bridges were found in all cases, and fluorescence in situ hybridization demonstrated extensive structural rearrangements of chromosomes, with terminal transferase detection showing fragmented DNA in 5-20% of interphase cells. Less than 2% of cells showed evidence of necrosis or apoptosis, and telomerase was expressed in the majority of cases. Telomeric dysfunction may thus trigger chromosomal fragmentation through persistent bridge-breakage events in pancreatic carcinomas and osteosarcomas, leading to a continuous reorganization of the tumor genome. Telomerase expression is not sufficient for completely stabilizing the chromosome complement but may be crucial for preventing complete genomic deterioration and maintaining cellular survival.
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| 5. |
- Petersén, Åsa, et al.
(författare)
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Brain-derived neurotrophic factor inhibits apoptosis and dopamine-induced free radical production in striatal neurons but does not prevent cell death
- 2001
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Ingår i: Brain Research Bulletin. - 0361-9230. ; 56:3-4, s. 331-335
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Tidskriftsartikel (refereegranskat)abstract
- In hereditary Huntington's disease, a triplet repeat disease, there is extensive loss of striatal neurons. It has been shown that brain-derived neurotrophic factor (BDNF) protects striatal neurons against a variety of insults. We confirmed that BDNF enhances survival and DARPP-32 expression in primary striatal cultures derived from postnatal mice. Furthermore, BDNF inhibited intracellular oxyradical stress triggered by dopamine, and partially blocked basal and dopamine-induced apoptosis. Nevertheless, BDNF failed to rescue striatal neurons from dopamine-induced cell death. Therefore, BDNF inhibits free radical and apoptotic pathways in medium spiny neurons, but does so downstream from the point of commitment to cell death.
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| 6. |
- Petersén, Åsa
(författare)
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Effects of dopamine and excitotoxicity in experimental models of Huntington's disease
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by an expansion of a CAG repeat in the HD gene, that leads to dysfunction and death of striatal neurons. The pathogenetic mechanisms underlying HD are not known, but excitotoxicity and dopamine (DA) have been suggested to play a role. In this thesis, the effects of excitotoxicity and DA have been studied in striatal in vitro and in vivo models of HD. I examined the effect of brain-derived neurotrophic factor and ciliary neurotrophic factor on excitotoxin- and DA-induced toxicity, as well as the mechanisms involved in cell death after increased intracellular calcium in striatal neurons. I showed that two transgenic HD mice with expanded CAG repeats in exon 1 of the HD gene (R6 mice) are completely resistant to intrastriatal injections of the excitotoxin quinolinic acid (QA). However, no change in susceptibility to QA was found in transgenic HD mice expressing a 3 kb part of the HD gene, regardless of repeat length and age. Interestingly, when studying the effect of DA on R6 mice, there was an age-dependent change in susceptibility to DA-mediated toxicity. Cultures of postnatal striatal R6 neurons exhibited an increased sensitivity to DA, more cell death, production of free radicals and formation of ubiquitinated aggregates in the cytosol compared to normal neurons. When DA was injected intrastriatally into R6/1 mice, they displayed a normal sensitivity to DA at 3 weeks of age, and a partial resistance at 16 weeks of age. At the time of resistance, dopaminergic neurons from R6 mice displayed reduced soma areas in the substantia nigra pars compacta, and decreased levels of DA both at baseline and after exposure to the DA-releasing agent malonate (using microdialysis), indicating an effect of the transgene on the nigrostriatal system in these mice. Exposure of striatal neurons from R6 mice to DA induced autophagy both in vitro and in vivo. The findings in this thesis point to an important role of DA and autophagy in HD pathogenesis.
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| 7. |
- Petersén, Åsa, et al.
(författare)
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Evidence for Dysfunction of the Nigrostriatal Pathway in the R6/1 Line of Transgenic Huntington's Disease Mice.
- 2002
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Ingår i: Neurobiology of Disease. - : Elsevier BV. - 0969-9961. ; 11:1, s. 134-146
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Tidskriftsartikel (refereegranskat)abstract
- The present multidisciplinary study examined nigrostriatal dopamine and striatal amino acid transmission in the R6/1 line of transgenic Huntington's disease (HD) mice expressing exon 1 of the HD gene with 115 CAG repeats. Although the number of tyrosine hydroxylase-positive neurons was not reduced and nigrostriatal connectivity remained intact in 16-week-old R6/1 mice, the size of tyrosine hydroxylase-positive neurons in the substantia nigra was reduced by 15%, and approximately 30% of these cells exhibited aggregated huntingtin. In addition, using in vivo microdialysis, we found that basal extracellular striatal dopamine levels were reduced by 70% in R6/1 mice compared to their wild-type littermates. Intrastriatal perfusion with malonate in R6/1 mice resulted in a short-lasting, attenuated increase in local dopamine release compared to wild-type mice. Furthermore, the size of the malonate-induced striatal lesion was 80% smaller in these animals. Taken together, these findings suggest that a functional deficit in nigrostriatal dopamine transmission may contribute to the behavioral phenotype and the resistance to malonate-induced neurotoxicity characteristic of R6/1 HD mice.
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| 8. |
- Petersén, Åsa, et al.
(författare)
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Expanded CAG repeats in exon 1 of the Huntington's disease gene stimulate dopamine-mediated striatal neuron autophagy and degeneration
- 2001
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 10:12, s. 1243-1254
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Tidskriftsartikel (refereegranskat)abstract
- Huntington's disease (HD) is caused by an expanded CAG repeat in exon 1 of the gene coding for the huntingtin protein. The cellular pathway by which this mutation induces HD remains unknown, although alterations in protein degradation are involved, To study intrinsic cellular mechanisms involved, To study Intrinsic to the mutation, we examined dissociated postnatally derived cultures of striatal neurons from transgenic mice expressing exon 1 of the human HD gene carrying a CAG repeat expansion. While there was no difference in cell death between wild-type and mutant littermate-derived cultures, the mutant striatal neurons exhibited elevated cell death following a single exposure to a neurotoxic concentration of dopamine, The mutant neurons exposed to dopamine also exhibited lysosome-associated responses including induction of autophagic granules and electron-dense lysosomes, The autophagic/lysosomal compartments co-localized with high levels of oxygen radicals in living neurons, and ubiquitin. The results suggest that the combination of mutant huntingtin and a source of oxyradical stress (provided in this case by dopamine) induces autophagy and may underlie the selective cell death characteristic of HD.
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| 9. |
- Petersén, Åsa, et al.
(författare)
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Grafting of nigral tissue hibernated with tirilazad mesylate and glial cell line-derived neurotrophic factor
- 2000
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Ingår i: Cell Transplantation. - 1555-3892. ; 9:5, s. 577-584
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Tidskriftsartikel (refereegranskat)abstract
- Transplantation of embryonic ventral mesencephalon is a potential therapy for patients with Parkinson's disease. As only around 5-10% of embryonic dopaminergic neurons survive grafting into the adult striatum, it is considered necessary to use multiple donor embryos. To increase the survival of the grafted dopaminergic neurons, the clinical transplantation program in Lund currently employs the lipid peroxidation inhibitor, tirilazad mesylate, in all solutions used during tissue storage, preparation, and transplantation. However, the difficulty in obtaining a sufficient number of donor embryos still remains an important limiting factor for the clinical application of neural transplantation. In many clinical transplantation programs, it would be a great advantage if human nigral donor tissue could be stored for at least 1 week. This study was performed in order to investigate whether storage of embryonic tissue at 4 degrees C for 8 days can be applied clinically without creating a need to increase the number of donors. We compared the survival of freshly grafted rat nigral tissue, prepared according to the clinical protocol, with tissue transplanted after hibernation. Thus, in all groups tirilazad mesylate was omnipresent. One group of rats was implanted with fresh tissue and three groups with hibernated tissue with or without addition of glial cell line-derived neurotrophic factor (GDNF) in the hibernation medium and/or the final cell suspension. Earlier studies have suggested that GDNF improves the survival of hibernated nigral transplants. We found no statistically significant difference between the groups regarding graft survival after 3 weeks. However, there was a nonsignificant trend for fewer surviving dopaminergic neurons in grafts from hibernated tissue compared to fresh controls. Furthermore, we show that the addition of GDNF to the hibernation medium and/or to the final cell suspension does not significantly increase the survival of the dopaminergic neurons.
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| 10. |
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