| 1. |
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| 2. |
- Akkuratov, Evgeny E., et al.
(författare)
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Neanderthal and Denisovan ancestry in Papuans : A functional study
- 2018
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Ingår i: Journal of Bioinformatics and Computational Biology. - : Imperial College Press. - 0219-7200 .- 1757-6334. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- Sequencing of complete nuclear genomes of Neanderthal and Denisovan stimulated studies about their relationship with modern humans demonstrating, in particular, that DNA alleles from both Neanderthal and Denisovan genomes are present in genomes of modern humans. The Papuan genome is a unique object because it contains both Neanderthal and Denisovan alleles. Here, we have shown that the Papuan genomes contain different gene functional groups inherited from each of the ancient people. The Papuan genomes demonstrate a relative prevalence of Neanderthal alleles in genes responsible for the regulation of transcription and neurogenesis. The enrichment of specific functional groups with Denisovan alleles is less pronounced; these groups are responsible for bone and tissue remodeling. This analysis shows that introgression of alleles from Neanderthals and Denisovans to Papuans occurred independently and retention of these alleles may carry specific adaptive advantages.
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| 3. |
- Akkuratov, Evgeny E., et al.
(författare)
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Ouabain Modulates the Functional Interaction Between Na,K-ATPase and NMDA Receptor.
- 2020
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Ingår i: Molecular Neurobiology. - : Springer Science and Business Media LLC. - 0893-7648 .- 1559-1182. ; 57:10, s. 4018-4030
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Tidskriftsartikel (refereegranskat)abstract
- The N-methyl-D-aspartate (NMDA) receptor plays an essential role in glutamatergic transmission and synaptic plasticity and researchers are seeking for different modulators of NMDA receptor function. One possible mechanism for its regulation could be through adjacent membrane proteins. NMDA receptors coprecipitate with Na,K-ATPase, indicating a potential interaction of these two proteins. Ouabain, a mammalian cardiotonic steroid that specifically binds to Na,K-ATPase and affects its conformation, can protect from some toxic effects of NMDA receptor activation. Here we have examined whether NMDA receptor activity and downstream effects can be modulated by physiological ouabain concentrations. The spatial colocalization between NMDA receptors and the Na,K-ATPase catalytic subunits on dendrites of cultured rat hippocampal neurons was analyzed with super-resolution dSTORM microscopy. The functional interaction was analyzed with calcium imaging of single hippocampal neurons exposed to 10 μM NMDA in presence and absence of ouabain and by determination of the ouabain effect on NMDA receptor-dependent long-term potentiation. We show that NMDA receptors and the Na,K-ATPase catalytic subunits alpha1 and alpha3 exist in same protein complex and that ouabain in nanomolar concentration consistently reduces the calcium response to NMDA. Downregulation of the NMDA response is not associated with internalization of the receptor or with alterations in its state of Src phosphorylation. Ouabain in nanomolar concentration elicits a long-term potentiation response. Our findings suggest that ouabain binding to a fraction of Na,K-ATPase molecules that cluster with the NMDA receptors will, via a conformational effect on the NMDA receptors, cause moderate but consistent reduction of NMDA receptor response at synaptic activation.
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| 4. |
- Akkuratov, Evgeny E.
(författare)
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The Biophysics of Na+,K+-ATPase in neuronal health and disease
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Na+,K+-ATPase is one of the most important proteins in the mammalian cell. It creates sodium and potassium gradients which are fundamental for the membrane potential and sodium-dependent secondary active transport. It has a second role in the cell as a receptor that by binding chemicals from the cardiotonic steroids family, the most knowledgeable of them is ouabain, triggers various signaling pathways in the cell which regulate gene activation, proliferation, apoptosis, etc. It has been shown that several severe neurological diseases are associated with mutations in the Na+,K+-ATPase encoding genes. Although Na+,K+-ATPase was discovered already in 1957 by the Danish scientist Jens Skou, the knowledge about the function of this enzyme is still not complete. In the studies included in the thesis, we have learned more about the function of Na+,K+-ATPase in different aspects of health and disease. In study I we showed a mechanism of ouabain-dependent regulation of the NMDA receptor, one of the most important receptors in the nervous system, via binding with Na+,K+-ATPase. This allows us to look at the Na+,K+-ATPase as regulator via protein-protein interaction. In study II we investigated a different aspect of Na+,K+-ATPase functioning – to look at how binding of ouabain to Na+,K+-ATPase activates a number of signaling cascades by looking at the phosphoproteome status of the cells. This allows us to see the whole picture of ouabain-mediated cascades and further characterize them. In study III we focused on the role of Na+,K+-ATPase in severe epileptic encephalopathy caused by a mutation in the ATP1A1 gene. We performed a molecular and cellular study to describe how mutations affects protein structure and function and found that this mutation converts the ion pump to a nonspecific leak channel. In study IV we performed a translational study of the most common mutation for rapid-onset dystonia-parkinsonism. We studied how this mutation affects the nervous system on the protein-, cellular-, and organism level and found that the complete absence of ultraslow afterhyperpolarization (usAHP) could explain gait disturbances found in patients. In the on-going study we showed that Na+,K+-ATPase can oligomerize and that this effect is triggered by ouabain binding to the Na+,K+-ATPase. In this study, we utilized a novel fluorescence labelling approach and used biophysical techniques with single molecule sensitivity to track Na+,K+-ATPase interactions. In summary, we applied biophysical and molecular methods to study different aspects of the function of Na+,K+-ATPase, and gained insights that could be helpful not only for answering fundamental questions about Na+,K+-ATPase but also to find a treatment for patients with diseases associated with mutations in this protein.
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| 5. |
- Aperia, Anita Chatarina, et al.
(författare)
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Na+, K+-ATPase, a new class of plasma membrane receptors
- 2016
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Ingår i: American Journal of Physiology - Cell Physiology. - : American Physiological Society. - 0363-6143 .- 1522-1563. ; 310:7, s. C491-C495
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Tidskriftsartikel (refereegranskat)abstract
- The Na(+), K(+)-ATPase (NKA) differs from most other ion transporters not only in its capacity to maintain a steep electrochemical gradient across the plasma membrane but also as a receptor for a family of cardiotonic steroids, to which ouabain belongs. Studies from many groups, performed during the last fifteen years, have demonstrated that ouabain, a member of the cardiotonic steroid family, can activate a network of signaling molecules and that NKA will also serve as a signal transducer that can provide a feed back loop between NKA and the mitochondria. This brief review summarizes the current knowledge and controversies with regard to the understanding of NKA signaling.
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| 6. |
- Azarias, Guillaume, et al.
(författare)
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A Specific and Essential Role for Na,K-ATPase alpha 3 in Neurons Co-expressing alpha 1 and alpha 3
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:4, s. 2734-2743
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Tidskriftsartikel (refereegranskat)abstract
- Most neurons co-express two catalytic isoforms of Na,K-ATPase, the ubiquitous alpha 1, and the more selectively expressed alpha 3. Although neurological syndromes are associated with alpha 3 mutations, the specific role of this isoform is not completely understood. Here, we used electrophysiological and Na+ imaging techniques to study the role of alpha 3 in central nervous system neurons expressing both isoforms. Under basal conditions, selective inhibition of alpha 3 using a low concentration of the cardiac glycoside, ouabain, resulted in a modest increase in intracellular Na+ concentration ([Na+](i)) accompanied by membrane potential depolarization. When neurons were challenged with a large rapid increase in [Na+](i), similar to what could be expected following suprathreshold neuronal activity, selective inhibition of alpha 3 almost completely abolished the capacity to restore [Na+](i) in soma and dendrite. Recordings of Na, K-ATPase specific current supported the notion that when [Na+](i) is elevated in the neuron, alpha 3 is the predominant isoform responsible for rapid extrusion of Na+. Low concentrations of ouabain were also found to disrupt cortical network oscillations, providing further support for the importance of alpha 3 function in the central nervous system. The alpha isoforms express a well conserved protein kinase A consensus site, which is structurally associated with an Na+ binding site. Following activation of protein kinase A, both the alpha 3-dependent current and restoration of dendritic [Na+](i) were significantly attenuated, indicating that alpha 3 is a target for phosphorylation and may participate in short term regulation of neuronal function.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Lopachev, A. V., et al.
(författare)
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Comparative Action of Cardiotonic Steroids on Intracellular Processes in Rat Cortical Neurons
- 2018
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Ingår i: Biochemistry (Moscow). - : MAIK NAUKA/INTERPERIODICA/SPRINGER. - 0006-2979 .- 1608-3040. ; 83:2, s. 140-151
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Tidskriftsartikel (refereegranskat)abstract
- Binding to Na+,K+-ATPase, cardiotonic steroids (CTS) activate intracellular signaling cascades that affect gene expression and regulation of proliferation and apoptosis in cells. Ouabain is the main CTS used for studying these processes. The effects of other CTS on nervous tissue are practically uncharacterized. Previously, we have shown that ouabain affects the activation of mitogen-activated protein kinases (MAP kinases) ERK1/2, p38, and JNK. In this study, we compared the effects of digoxin and bufalin, which belong to different subclasses of CTS, on primary culture of rat cortical cells. We found that CTS toxicity is not directly related to the degree of Na+,K+-ATPase inhibition, and that bufalin and digoxin, like ouabain, are capable of activating ERK1/2 and p38, but with different concentration and time profiles. Unlike bufalin and ouabain, digoxin did not decrease JNK activation after long-term incubation. We concluded that the toxic effect of CTS in concentrations that inhibit less than 80% of Na+,K+-ATPase activity is related to ERK1/2 activation as well as the complex profile of MAP kinase activation. A direct correlation between Na+,K+-ATPase inhibition and the degree of MAP kinase activation is only observed for ERK1/2. The different action of the three CTS on JNK and p38 activation may indicate that it is associated with intracellular signaling cascades triggered by protein-protein interactions between Na+,K+-ATPase and various partner proteins. Activation of MAP kinase pathways by these CTS occurs at concentrations that inhibit Na+,K+-ATPase containing the alpha 1 subunit, suggesting that these signaling cascades are realized via alpha 1. The results show that the signaling processes in neurons caused by CTS can differ not only because of different inhibitory constants for Na+,K+-ATPase.
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| 12. |
- Lopachev, Alexander, V, et al.
(författare)
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Ouabain-Induced Gene Expression Changes in Human iPSC-Derived Neuron Culture Expressing Dopamine and cAMP-Regulated Phosphoprotein 32 and GABA Receptors
- 2021
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Ingår i: Brain Sciences. - : MDPI. - 2076-3425. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- Cardiotonic steroids (CTS) are specific inhibitors and endogenous ligands of a key enzyme in the CNS-the Na+, K+-ATPase, which maintains and creates an ion gradient on the plasma membrane of neurons. CTS cause the activation of various signaling cascades and changes in gene expression in neurons and other cell types. It is known that intracerebroventricular injection of cardiotonic steroid ouabain causes mania-like behavior in rodents, in part due to activation of dopamine-related signaling cascades in the dopamine and cAMP-regulated phosphoprotein 32 (DARPP-32) expressing medium spiny neurons in the striatum. Dopaminergic projections in the striatum innervate these GABAergic medium spiny neurons. The objective of this study was to assess changes in the expression of all genes in human iPSC-derived expressing DARPP-32 and GABA receptors neurons under the influence of ouabain. We noted a large number of statistically significant upregulated and downregulated genes after a 16-h incubation with non-toxic concentration (30 nM) of ouabain. These changes in the transcriptional activity were accomplished with activation of MAP-kinase ERK1/2 and transcriptional factor cAMP response element-binding protein (CREB). Thus, it can be concluded that 30 nM ouabain incubated for 16 h with human iPSC-derived expressing DARPP-32 and GABA receptors neurons activates genes associated with neuronal maturation and synapse formation, by increasing the expression of genes associated with translation, vesicular transport, and increased electron transport chain function. At the same time, the expression of genes associated with proliferation, migration, and early development of neurons decreases. These data indicate that non-toxic concentrations of ouabain may induce neuronal maturation, neurite growth, and increased synaptogenesis in dopamine-receptive GABAergic neurons, suggesting formation of plasticity and the establishment of new neuronal junctions.
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| 13. |
- Nordahl, Linnea, et al.
(författare)
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Detection and quantification of Na,K-ATPase dimers in the plasma membrane of living cells by FRET-FCS
- 2024
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - : Elsevier BV. - 0304-4165 .- 1872-8006. ; 1868:7
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Tidskriftsartikel (refereegranskat)abstract
- The sodium potassium pump, Na,K-ATPase (NKA), is an integral plasma membrane protein, expressed in all eukaryotic cells. It is responsible for maintaining the transmembrane Na+ gradient and is the major determinant of the membrane potential. Self-interaction and oligomerization of NKA in cell membranes has been proposed and discussed but is still an open question. Here, we have used a combination of FRET and Fluorescence Correlation Spectroscopy, FRET-FCS, to analyze NKA in the plasma membrane of living cells. Click chemistry was used to conjugate the fluorescent labels Alexa 488 and Alexa 647 to non-canonical amino acids introduced in the NKA α1 and β1 subunits. We demonstrate that FRET-FCS can detect an order of magnitude lower concentration of green-red labeled protein pairs in a single-labeled red and green background than what is possible with cross-correlation (FCCS). We show that a significant fraction of NKA is expressed as a dimer in the plasma membrane. We also introduce a method to estimate not only the number of single and double labeled NKA, but the number of unlabeled, endogenous NKA and estimate the density of endogenous NKA at the plasma membrane to 1400 ± 800 enzymes/μm2.
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| 14. |
- Nordahl, Linnea, et al.
(författare)
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Direct Observation of Na,K‐ATPase Oligomers in The Plasma Membrane of Living Cells by FRET‐FCS
- 2022
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 36:S1
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Tidskriftsartikel (refereegranskat)abstract
- The sodium pump, Na,K-ATPase, is an integral plasma membrane protein, expressed in all eukaryotic cells. Na,K-ATPase transforms chemical energy from ATP into a gradient of Na+ and K+ over the plasma membrane by actively exporting three Na+ ions and importing two K+ ions for each hydrolyzed ATP. It is responsible for maintenance of the transmembrane Na+ gradient and is the major determinant of the membrane potential. It provides the driving force for all Na+-coupled transport processes, thereby controlling essential functions in the cell. Na,K-ATPase is formed by three subunits alpha/beta/FXYD, where alpha is the catalytic ion-transporting subunit, beta is a regulatory subunit and FXYD is accessory.Self-interaction and oligomerization of the Na,K-ATPase alpha/beta heterodimer in cell membranes has been proposed and discussed for a long time but is still an open question.Here we have used a combination of FRET and Fluorescence Correlation Spectroscopy, FRET-FCS, in order to detect oligomers of Na,K-ATPase. Compared to conventional cross-correlation FCCS, FRET-FCS is one to two orders of magnitude more sensitive when detecting oligomers. Moreover, FRET-FCS is inherently insensitive to unbalanced labeling, which is a great advantage during live cell measurements.We hypothesized that Na,K-ATPase can exist in a higher order oligomeric state and demonstrate the use of FRET-FCS to test this hypothesisWe have introduced fluorescent labels by using expression of non-canonical amino acid modified beta subunits. The FRET pair Alexa488 and Alexa647 was directly conjugated to the beta subunits using selective click chemistry. Conventional FCS measurements of labeled cells revealed the absolute density of labeled and unlabeled Na,K-ATPase. With FRET-FCS we could observe FRET signals and FCS curves demonstrating the existence of oligomers. Positive controls for the FRET-FCS measurements were constructed by labeling alpha subunits with Alexa488 and beta subunits with Alexa647.Furthermore, we performed Monte Carlo simulations of Na,K-ATPase, as monomer and as oligomer of increasing order, together with its ligands in a picket and fence diffusion model of the plasma membrane. The simulations suggest that oligomerization can have an impact on the net efficiency of the Na,K-ATPase measured as ATP turnover.In conclusion we find that Na,K-ATPase can be found in the plasma membrane as oligomers. Further we discuss the consequences of oligomerization and propose that it can have a regulatory effect for the Na,K-ATPase net efficiency.
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| 15. |
- Panizza, Elena, et al.
(författare)
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Ouabain-regulated phosphoproteome reveals molecular mechanisms for Na+, K+-ATPase control of cell adhesion, proliferation, and survival
- 2019
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Ingår i: The FASEB Journal. - : FEDERATION AMER SOC EXP BIOL. - 0892-6638 .- 1530-6860. ; 33:9, s. 10193-10206
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Tidskriftsartikel (refereegranskat)abstract
- The ion pump Na+, K+-ATPase (NKA) is a receptor for the cardiotonic steroid ouabain. Subsaturating concentration of ouabain triggers intracellular calcium oscillations, stimulates cell proliferation and adhesion, and protects from apoptosis. However, it is controversial whether ouabain-bound NKA is considered a signal transducer. To address this question, we performed a global analysis of protein phosphorylation in COS-7 cells, identifying 2580 regulated phosphorylation events on 1242 proteins upon 10- and 20-min treatment with ouabain. Regulated phosphorylated proteins include the inositol triphosphate receptor and stromal interaction molecule, which are essential for initiating calcium oscillations. Hierarchical clustering revealed that ouabain triggers a structured phosphorylation response that occurs in a well-defined, time-dependent manner and affects specific cellular processes, including cell proliferation and cell-cell junctions. We additionally identify regulation of the phosphorylation of several calcium and calmodulin-dependent protein kinases (CAMKs), including 2 sites of CAMK type II-gamma (CAMK2G), a protein known to regulate apoptosis. To verify the significance of this result, CAMK2G was knocked down in primary kidney cells. CAMK2G knockdown impaired ouabain-dependent protection from apoptosis upon treatment with high glucose or serum deprivation. In conclusion, we establish NKA as the coordinator of a broad, tightly regulated phosphorylation response in cells and define CAMK2G as a downstream effector of NKA.-Panizza, E., Zhang, L., Fontana, J. M., Hamada, K., Svensson, D., Akkuratov, E. E., Scott, L., Mikoshiba, K., Brismar, H., Lehtio, J., Aperia, A. Ouabain-regulated phosphoproteome reveals molecular mechanisms for Na+, K+-ATPase control of cell adhesion, proliferation, and survival.
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| 16. |
- Petersen, Julian, et al.
(författare)
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A previously uncharacterized Factor Associated with Metabolism and Energy (FAME/C14orf105/CCDC198/1700011H14Rik) is related to evolutionary adaptation, energy balance, and kidney physiology
- 2023
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- In this study we use comparative genomics to uncover a gene with uncharacterized function (1700011H14Rik/C14orf105/CCDC198), which we hereby name FAME (Factor Associated with Metabolism and Energy). We observe that FAME shows an unusually high evolutionary divergence in birds and mammals. Through the comparison of single nucleotide polymorphisms, we identify gene flow of FAME from Neandertals into modern humans. We conduct knockout experiments on animals and observe altered body weight and decreased energy expenditure in Fame knockout animals, corresponding to genome-wide association studies linking FAME with higher body mass index in humans. Gene expression and subcellular localization analyses reveal that FAME is a membrane-bound protein enriched in the kidneys. Although the gene knockout results in structurally normal kidneys, we detect higher albumin in urine and lowered ferritin in the blood. Through experimental validation, we confirm interactions between FAME and ferritin and show co-localization in vesicular and plasma membranes.
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| 17. |
- Rivas-Carrillo, Salvador Daniel, et al.
(författare)
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MindReader : unsupervised electroencephalographic reader
- 2023
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Electroencephalogram (EEG) interpretation plays a critical role in the clinical assessment of neurological conditions, including epilepsy. Manual analysis requires highly specialized and heavily trained personnel. Moreover, the rate of capturing abnormal events makes interpretation time-consuming, resource-hungry, and, overall, an expensive process.Automatic detection offers the potential to improve the quality of patient care by shortening the time to diagnosis, managing big data, and optimizing the allocation of human resources.Findings: We present MindReader, an unsupervised method for EEG signals. First, MindReader processes the signal through an autoencoder in order to detect EEG abnormalities. Next, patterns are hypothesized by a Hidden Markov Model. Our algorithm automatically generates labels for non-pathological phases, thus reducing the search space for trained personnel.Conclusions: MindReader is effective in detecting EEG abnormalities in focal and generalized epilepsy.
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| 18. |
- Rivas-Carrillo, Salvador Daniel, et al.
(författare)
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MindReader : Unsupervised Classification of Electroencephalographic Data
- 2023
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 23:6, s. 2971-
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Tidskriftsartikel (refereegranskat)abstract
- Electroencephalogram (EEG) interpretation plays a critical role in the clinical assessment of neurological conditions, most notably epilepsy. However, EEG recordings are typically analyzed manually by highly specialized and heavily trained personnel. Moreover, the low rate of capturing abnormal events during the procedure makes interpretation time-consuming, resource-hungry, and overall an expensive process. Automatic detection offers the potential to improve the quality of patient care by shortening the time to diagnosis, managing big data and optimizing the allocation of human resources towards precision medicine. Here, we present MindReader, a novel unsupervised machine-learning method comprised of the interplay between an autoencoder network, a hidden Markov model (HMM), and a generative component: after dividing the signal into overlapping frames and performing a fast Fourier transform, MindReader trains an autoencoder neural network for dimensionality reduction and compact representation of different frequency patterns for each frame. Next, we processed the temporal patterns using a HMM, while a third and generative component hypothesized and characterized the different phases that were then fed back to the HMM. MindReader then automatically generates labels that the physician can interpret as pathological and non-pathological phases, thus effectively reducing the search space for trained personnel. We evaluated MindReader's predictive performance on 686 recordings, encompassing more than 980 h from the publicly available Physionet database. Compared to manual annotations, MindReader identified 197 of 198 epileptic events (99.45%), and is, as such, a highly sensitive method, which is a prerequisite for clinical use.
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| 19. |
- Seplyarskiy, Vladimir B., et al.
(författare)
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Error-prone bypass of DNA lesions during lagging-strand replication is a common source of germline and cancer mutations
- 2019
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Ingår i: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 51:1, s. 36-
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Tidskriftsartikel (refereegranskat)abstract
- Studies in experimental systems have identified a multitude of mutational mechanisms including DNA replication infidelity and DNA damage followed by inefficient repair or replicative bypass. However, the relative contributions of these mechanisms to human germline mutation remain unknown. Here, we show that error-prone damage bypass on the lagging strand plays a major role in human mutagenesis. Transcription-coupled DNA repair removes lesions on the transcribed strand; lesions on the non-transcribed strand are preferentially converted into mutations. In human polymorphism we detect a striking similarity between mutation types predominant on the non-transcribed strand and on the strand lagging during replication. Moreover, damage-induced mutations in cancers accumulate asymmetrically with respect to the direction of replication, suggesting that DNA lesions are resolved asymmetrically. We experimentally demonstrate that replication delay greatly attenuates the mutagenic effect of ultraviolet irradiation, confirming that replication converts DNA damage into mutations. We estimate that at least 10% of human mutations arise due to DNA damage.
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| 20. |
- Sigalova, Olga M., et al.
(författare)
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Chlamydia pan-genomic analysis reveals balance between host adaptation and selective pressure to genome reduction
- 2019
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Ingår i: BMC Genomics. - : BMC. - 1471-2164. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Chlamydia are ancient intracellular pathogens with reduced, though strikingly conserved genome. Despite their parasitic lifestyle and isolated intracellular environment, these bacteria managed to avoid accumulation of deleterious mutations leading to subsequent genome degradation characteristic for many parasitic bacteria. Results: We report pan-genomic analysis of sixteen species from genus Chlamydia including identification and functional annotation of orthologous genes, and characterization of gene gains, losses, and rearrangements. We demonstrate the overall genome stability of these bacteria as indicated by a large fraction of common genes with conserved genomic locations. On the other hand, extreme evolvability is confined to several paralogous gene families such as polymorphic membrane proteins and phospholipase D, and likely is caused by the pressure from the host immune system. Conclusions: This combination of a large, conserved core genome and a small, evolvable periphery likely reflect the balance between the selective pressure towards genome reduction and the need to adapt to escape from the host immunity.
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| 21. |
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| 22. |
- Ygberg, Sofia, et al.
(författare)
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A missense mutation converts the Na+,K+-ATPase into an ion channel and causes therapy-resistant epilepsy.
- 2021
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Ingår i: Journal of Biological Chemistry. - : Elsevier. - 0021-9258 .- 1083-351X. ; 297:6
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Tidskriftsartikel (refereegranskat)abstract
- The ion pump Na+,K+-ATPase is a critical determinant of neuronal excitability; however, its role in the etiology of diseases of the central nervous system (CNS) is largely unknown. We describe here the molecular phenotype of a Trp931Arg mutation of the Na+,K+-ATPase catalytic α1 subunit in an infant diagnosed with therapy-resistant lethal epilepsy. In addition to the pathological CNS phenotype, we also detected renal wasting of Mg2+. We found that membrane expression of the mutant α1 protein was low, and ion pumping activity was lost. Arginine insertion into membrane proteins can generate water-filled pores in the plasma membrane, and our molecular dynamic (MD) simulations of the principle states of Na+,K+-ATPase transport demonstrated massive water inflow into mutant α1 and destabilization of the ion-binding sites. MD simulations also indicated that a water pathway was created between the mutant arginine residue and the cytoplasm, and analysis of oocytes expressing mutant α1 detected a nonspecific cation current. Finally, neurons expressing mutant α1 were observed to be depolarized compared with neurons expressing wild-type protein, compatible with a lowered threshold for epileptic seizures. The results imply that Na+,K+-ATPase should be considered a neuronal locus minoris resistentia in diseases associated with epilepsy and with loss of plasma membrane integrity.
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| 23. |
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