| 1. |
- Zor, K., et al.
(författare)
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A compact multifunctional microfluidic platform for exploring cellular dynamics in real-time using electrochemical detection
- 2014
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:109, s. 63761-63771
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Tidskriftsartikel (refereegranskat)abstract
- Downscaling of microfluidic cell culture and detection devices for electrochemical monitoring has mostly focused on miniaturization of the microfluidic chips which are often designed for specific applications and therefore lack functional flexibility. We present a compact microfluidic cell culture and electrochemical analysis platform with in-built fluid handling and detection, enabling complete cell based assays comprising on-line electrode cleaning, sterilization, surface functionalization, cell seeding, cultivation and electrochemical real-time monitoring of cellular dynamics. To demonstrate the versatility and multifunctionality of the platform, we explored amperometric monitoring of intracellular redox activity in yeast (Saccharomyces cerevisiae) and detection of exocytotically released dopamine from rat pheochromocytoma cells (PC12). Electrochemical impedance spectroscopy was used in both applications for monitoring cell sedimentation and adhesion as well as proliferation in the case of PC12 cells. The influence of flow rate on the signal amplitude in the detection of redox metabolism as well as the effect of mechanical stimulation on dopamine release were demonstrated using the programmable fluid handling capability. The here presented platform is aimed at applications utilizing cell based assays, ranging from e.g. monitoring of drug effects in pharmacological studies, characterization of neural stem cell differentiation, and screening of genetically modified microorganisms to environmental monitoring.
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| 2. |
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| 3. |
- Ferencz, Istvan, et al.
(författare)
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Effects of cholinergic denervation on seizure development and neurotrophin messenger RNA regulation in rapid hippocampal kindling
- 1997
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Ingår i: Neuroscience. - 1873-7544. ; 80:2, s. 389-399
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Tidskriftsartikel (refereegranskat)abstract
- Intraventricular 192 IgG-saporin was used to induce a selective lesion of basal forebrain cholinergic neurons in rats. When subjected to 40 rapid hippocampal kindling stimulations with 5-min intervals, these animals exhibited increased number of generalized seizures and a higher mean seizure grade in response to the first five stimulations, and required fewer stimuli to develop focal behavioural seizures, as compared to non-lesioned rats. In contrast, both groups showed similarly enhanced responsiveness when test stimulated four weeks later. Using in situ hybridization, cholinergic denervation was found to cause a significant decrease of basal brain-derived neurotrophic factor messenger RNA levels in the hippocampal formation and piriform cortex, whereas gene expression for nerve growth factor, neurotrophin-3, and TrkB and TrkC was unchanged. Four weeks after rapid kindling stimulations, basal levels of brain-derived neurotrophic factor messenger RNA in the dentate granule cells were restored to normal in the lesioned rats, whereas neurotrophin-3 messenger RNA levels were decreased. No differences in the seizure-evoked levels of neurotrophin and Trk messenger RNAs were detected, except in the dentate granule cell layer, which had significantly higher brain-derived neurotrophic factor messenger RNA expression in the lesioned animals at 2 h. In conclusion, the basal forebrain cholinergic system (i) dampens the severity of recurring seizures induced by rapid hippocampal kindling stimulations, but has no effect on the subsequent delayed phase of epileptogenesis; and (ii) exerts a tonic stimulation of basal brain-derived neurotrophic factor messenger RNA levels in the hippocampal formation and piriform cortex. The findings also indicate that the cholinergic lesion does not affect neurotrophin and Trk gene expression after recurring seizures, and that the kindling process leads to long-term changes in basal brain-derived neurotrophic factor and neurotrophin-3 messenger RNA levels in the denervated animals.
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| 4. |
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| 5. |
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| 6. |
- Kokaia, Zaal, et al.
(författare)
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Regional brain-derived neurotrophic factor mRNA and protein levels following transient forebrain ischemia in the rat
- 1996
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Ingår i: Brain Research. Molecular Brain Research. - 0169-328X. ; 38:1, s. 139-144
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Tidskriftsartikel (refereegranskat)abstract
- Levels of BDNF mRNA and protein were measured in the rat brain using in situ hybridization and a two-site enzyme immunoassay. Under basal conditions, the highest BDNF concentration was found in the dentate gyrus (88 ng/g), while the levels in CA3 (50 ng/g), CA1 (18 ng/g) and parietal cortex (8 ng/g) were markedly lower. Following 10 min of forebrain ischemia, BDNF protein increased transiently in the dentate gyrus (to 124% of control at 6 h after the insult) and CA3 region (to 131% of control, at 1 week after the insult). In CA1 and parietal cortex, BDNF protein decreased to 73-75% of control at 24 h. In contrast, BDNF mRNA expression in dentate granule cells and CA3 pyramidal layer was transiently elevated to 287 and 293% of control, respectively, at 2 h, whereas no change was detected in CA1 or neocortex. The regional BDNF protein levels shown here correlate at least partly with regional differences in cellular resistance to ischemic damage, which is consistent with the hypothesis of a neuroprotective role of BDNF.
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| 7. |
- Pratt, G D, et al.
(författare)
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Differential regulation of N-methyl-D-aspartate receptor subunit messenger RNAs in kindling-induced epileptogenesis
- 1993
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Ingår i: Neuroscience. - 0306-4522. ; 57:2, s. 18-307
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Tidskriftsartikel (refereegranskat)abstract
- N-methyl-D-aspartate-receptors are implicated in several neuropathological conditions including epilepsy. As a model of complex partial seizures, rapid hippocampal kindling was chosen to investigate changes in the expression of messenger RNAs encoding the N-methyl-D-aspartate-receptor subunits NR1, NR2A and NR2B both during and in the period immediately following the induction of the kindled state. The study demonstrates a cell-specific, time-dependent modulation of the N-methyl-D-aspartate-receptor subunit messenger RNAs almost entirely restricted to the granule cells of the dentate gyrus. In partially kindled animals (10 stimulations), while the NR1 subunit messenger RNA remained unaltered after a period of 2 h, the NR2A and NR2B subunit messenger RNAs were bilaterally reduced in dentate gyrus granule cells by around 50% below control values. In fully kindled animals (40 stimulations), a progressive reduction in NR1 subunit messenger RNA levels in the dentate gyrus was observed, being maximal after 4 h (-67%). At the same time point, NR2A and NR2B transcript levels were transiently increased by 102% and 46% above control values, respectively. These data point to a differential regulation of N-methyl-D-aspartate-receptor subunit messenger RNAs. No alterations were detected in pyramidal cells. Long-term maintenance of the kindled state was not associated with alterations in N-methyl-D-aspartate-receptor subunit messenger RNAs since control levels of messenger RNA were attained by 12 h and persisted for at least five days. The early changes in messenger RNAs described in this study indicate that the expression of N-methyl-D-aspartate-receptor subunits is under independent regulatory control. This phenomenon may contribute to epileptogenesis and to kindling-associated plasticity by mediating a structural reorganization of N-methyl-D-aspartate-receptors, leading to an altered excitability of dentate gyrus granule cells.
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| 8. |
- Trajkovska, V., et al.
(författare)
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BDNF downregulates 5-HT2A receptor protein levels in hippocampal cultures
- 2009
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Ingår i: Neurochemistry International. - : Elsevier BV. - 0197-0186. ; 55:7, s. 697-702
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Tidskriftsartikel (refereegranskat)abstract
- Both brain-derived neurotrophic factor (BDNF) and the serotonin receptor 2A (5-HT2A) have been related to depression pathology. Specific 5-HT2A receptor changes seen in BDNF conditional mutant mice suggest that BDNF regulates the 5-HT2A receptor level. Here we show a direct effect of BDNF on 5-HT2A receptor protein levels in primary hippocampal neuronal and mature hippocampal organotypic cultures exposed to different BDNF concentrations for either 1, 3, 5 or 7 days. In vivo effects of BDNF on hippocampal 5-HT2A receptor levels were further corroborated in (BDNF +/-) mice with reduced BDNF levels. In primary neuronal cultures, 7 days exposure to 25 and 50 ng/mL BDNF resulted in downregulation of 5-HT2A, but not of 5-HT1A, receptor protein levels. The BDNF-associated downregulation of 5-HT2A receptor levels was also observed in mature hippocampal organotypic cultures, excluding confounding effects of BDNF on immature tissue. BDNF +/- mice showed significant increased 5-HT2A receptor levels in hippocampus confirming the association between 5-HT2A receptor and BDNF levels in vivo. In conclusion, our results point to a regulatory role of BDNF on 5-HT2A receptor levels. This interaction may be an important mechanism in the role of BDNF in affective disorders emphasizing the need for further elucidating the specificity and the mechanism behind this regulation. (C) 2009 Elsevier Ltd. All rights reserved.
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| 9. |
- Wickham, J, et al.
(författare)
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Cell-specific switch for epileptiform activity : critical role of interneurons in the mouse subicular network
- 2023
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1460-2199 .- 1047-3211. ; 33:10, s. 6171-6183
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Tidskriftsartikel (refereegranskat)abstract
- During epileptic seizures, neuronal network activity is hyper synchronized whereby GABAergic parvalbumin-interneurons may have a key role. Previous studies have mostly utilized 4-aminopyridine to induce epileptiform discharges in brain slices from healthy animals. However, it is not clear if the seizure-triggering ability of parvalbumin-interneurons also holds true without the use of external convulsive agents. Here, we investigate whether synchronized activation of parvalbumin-interneurons or principal cells can elicit epileptiform discharges in subiculum slices of epileptic mice. We found that selective synchronized activation of parvalbumin-interneurons or principal cells with optogenetics do not result in light-induced epileptiform discharges (LIEDs) neither in epileptic nor in normal brain slices. Adding 4-aminopyridine to slices, activation of parvalbumin-interneurons still failed to trigger LIEDs. In contrast, such activation of principal neurons readily generated LIEDs with features resembling afterdischarges. When GABAA receptor blocker was added to the perfusion medium, the LIEDs were abolished. These results demonstrate that in subiculum, selective synchronized activation of principal excitatory neurons can trigger epileptiform discharges by recruiting a large pool of downstream interneurons. This study also suggests region-specific role of principal neurons and interneurons in ictogenesis, opening towards differential targeting of specific brain areas for future treatment strategies tailored for individual patients with epilepsy.
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| 10. |
- Arvidsson, Andreas, et al.
(författare)
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Stroke induces widespread changes of gene expression for glial cell line-derived neurotrophic factor family receptors in the adult rat brain
- 2001
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Ingår i: Neuroscience. - 1873-7544. ; 106:1, s. 27-41
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Tidskriftsartikel (refereegranskat)abstract
- Gene expression for glial cell line-derived neurotrophic factor (GDNF) family ligands and receptors was analyzed with in situ hybridization after two focal ischemic insults of different severities. Focal ischemia was induced in rats by either 30 min or 2 h of middle cerebral artery occlusion (MCAO), causing damage to the striatum only, or involving also the parietal cortex, respectively. We found modest, transient elevation of GDNF mRNA in the dentate granule cell layer. In addition, the number of GDNF mRNA-expressing cells increased in the cortex and striatum after 2 h or 30 min of MCAO, respectively. No changes of neurturin or persephin mRNA expression were detected. Both c-Ret and GFRalpha1 mRNA levels were markedly increased in the ipsilateral cortex outside the ischemic lesion at 6-24 h after the 2-h insult, whereas GFRalpha2 expression was decreased in cortical areas both within and outside the lesion. Similar increases of c-Ret and GFRalpha1 mRNA levels were detected in the striatum, and to a lesser extent, in the cortex following 30 min of MCAO. The 2-h insult also gave rise to transient increases of c-Ret and GFRalpha1 mRNA in hippocampal subregions. Thirty minutes and 2 h of MCAO lead to elevated c-Ret, and GFRalpha1 or GFRalpha2 mRNA expression, respectively, in the ipsilateral ventroposterolateral thalamic nucleus. Both insults induced increased levels of GFRalpha1 mRNA in the subventricular zone of the lateral ventricle.Our data indicate major changes of GDNF family signaling in the forebrain, regulated mainly through altered receptor levels, in the post-ischemic phase. These changes could enhance neuroprotective and neuroregenerative responses both to endogenous and exogenous GDNF ligands.
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