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| 2. |
- Hansson, Magnus, et al.
(författare)
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Increased potassium conductance of brain mitochondria induces resistance to permeability transition by enhancing matrix volume.
- 2010
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 285, s. 741-750
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Tidskriftsartikel (refereegranskat)abstract
- Modulation of K+ conductance of the inner mitochondrial membrane has been proposed to mediate preconditioning in ischemia-reperfusion injury. The mechanism is not entirely understood but it has been linked to a decreased activation of mitochondrial permeability transition (mPT). In the present study, K+ channel activity was mimicked by picomolar concentrations of valinomycin. Isolated brain mitochondria were exposed to continuous infusions of calcium. Monitoring of extramitochondrial Ca2+ and mitochondrial respiration provided a quantitative assay for mPT-sensitivity by determining calcium retention capacity (CRC). Valinomycin and cyclophilin D-inhibition separately and additively increased CRC. Comparable degrees of respiratory uncoupling induced by increased K+ or H+ conductance had opposite effects on mPT sensitivity. Protonophores dose-dependently decreased CRC, demonstrating that so-called mild uncoupling was not beneficial per se. The putative mitoKATP channel opener diazoxide did not mimic the effect of valinomycin. An alkaline matrix pH was required in order for mitochondria to retain calcium, but increased K+ conductance did not result in augmented DeltapH. The beneficial effect of valinomycin on CRC was not mediated by H2O2-induced PKCepsilon activation. In contrast, increased K+ conductance reduced H2O2 generation during calcium infusion. Lowering the osmolarity of the buffer induced an increase in mitochondrial volume and improved CRC similar to valinomycin without inducing uncoupling or otherwise affecting respiration. We propose that increased potassium conductance in brain mitochondria may cause a direct physiological effect on matrix volume inducing resistance to pathological calcium challenges.
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| 3. |
- Krogh, Morten, et al.
(författare)
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A probabilistic treatment of the missing spot problem in 2D gel electrophoresis experiments
- 2007
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 6:8, s. 3335-3343
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional SIDS-PAGE gel electrophoresis using post-run staining is widely used to measure the abundances of thousands of protein spots simultaneously. Usually, the protein abundances of two or more biological groups are compared using biological and technical replicates. After gel separation and staining, the spots are detected, spot volumes are quantified, and spots are matched across gels. There are almost always many missing values in the resulting data set. The missing values arise either because the corresponding proteins have very low abundances (or are absent) or because of experimental errors such as incomplete/over focusing in the first dimension or varying run times in the second dimension as well as faulty spot detection and matching. In this study, we show that the probability for a spot to be missing can be modeled by a logistic regression function of the logarithm of the volume. Furthermore, we present an algorithm that takes a set of gels with technical and biological replicates as input and estimates the average protein abundances in the biological groups from the number of missing spots and measured volumes of the present spots using a maximum likelihood approach. Confidence intervals for abundances and p-values for differential expression between two groups are calculated using bootstrap sampling. The algorithm is compared to two standard approaches, one that discards missing values and one that sets all missing values to zero. We have evaluated this approach in two different gel data sets of different biological origin. An F-program, implementing the algorithm, is freely available at httP://bioinfo.thep.lu.se/MissingValues2Dgels.html.
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| 4. |
- Rickhag, Mattias, et al.
(författare)
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Rapid and long-term induction of effector immediate early genes (BDNF, Neuritin and Arc) in peri-infarct cortex and dentate gyrus after ischemic injury in rat brain.
- 2007
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Ingår i: Brain Research. - : Elsevier BV. - 1872-6240 .- 0006-8993. ; 1151, s. 203-210
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Tidskriftsartikel (refereegranskat)abstract
- The genomic response following brain ischemia is very complex and involves activation of both protective and detrimental signaling pathways. Immediate early genes (IEGs) represent the first wave of gene expression following ischemia and are induced in extensive regions of the ischemic brain including cerebral cortex and hippocampus. Brain-derived neurotrophic factor (BDNF), Neuritin and Activity-regulated cytoskeleton-associated protein (Arc) belong to a subgroup of immediate early genes implicated in synaptic plasticity known as effector immediate early genes. Here, we investigated the spatial and temporal activation pattern for these genes during the first 24 h of reperfusion following 2-h occlusion of the middle cerebral artery. Neuritin showed a persistent activation in frontal-cingulate cortex while Arc displayed a biphasic response. Also, in dentate gyrus, activation was observed at 0–6 h of reperfusion for Neuritin and 0–12 h of reperfusion for Arc while BDNF was induced 0–9 h of reperfusion. Our study demonstrates a rapid and long-term activation of effector immediate early genes in distinct brain areas following ischemic injury in rat. Effector gene activation may be part of long-term synaptic responses of ischemic brain tissue.
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| 5. |
- Teilum, Maria, et al.
(författare)
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Hypothermia Affects Translocation of Numerous Cytoplasmic Proteins Following Global Cerebral Ischemia.
- 2007
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 6:7, s. 2822-2832
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Tidskriftsartikel (refereegranskat)abstract
- Using a decapitation ischemia model, we studied translocation of proteins to and from the cytosol in normothermic (NT) and hypothermic (HT) rat brains. 2D gel analysis identified 74 proteins whose cytosolic level changed significantly after 15 min of ischemia. HT preserved the cytosolic levels of several glycolytic enzymes, as well as many plasticity related proteins, otherwise decreased following NT ischemia. The levels of redox-related proteins was lower in HT than in NT. Our results indicate that translocation of proteins to and from the cytosol is an important issue during ischemia.
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