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Electrochemical biosensors with spatially separated enzymatic and detection parts for selective analysis in flow-through arrangement
Tvorynska, Sofiia ; Barek, Jiří (advisor) ; Labuda, Ján (referee) ; Korecká, Lucie (referee)
This dissertation thesis presents the newly developed four highly reusable, stable as well as simple, and cost-effective electrochemical (bi)enzymatic biosensors for the selective and reliable determination of choline, acetylcholine, uric acid, and L-lactic acid in flow injection analysis. All biosensors are based on the concept of the spatial separation of the biorecognition part from detection one and amperometric monitoring of the enzymatically consumed oxygen via its four-electron reduction at the highly negative detection potential. In this way, the design of the biosensors includes an easily replaceable enzymatic mini-reactor(s) connected upstream to the flow cell that contains the appropriate silver amalgam-based transducer. The enzymatic mini-reactor based on choline oxidase, uricase, or lactate oxidase was used for choline, uric acid, or L-lactic acid biosensors, respectively. The acetylcholine bienzymatic biosensor includes the consequently connected choline oxidase- and acetylcholinesterase-based mini-reactors. The first part of this thesis focuses on the construction of two different silver amalgam-based electrodes. Specifically, this section discusses the fabrication of a silver solid amalgam electrode covered by mercury film operating in a wall-jet cell and also highlights the...
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Gen expresion of high affinity choline transporter in mouse model of Alzheimer's disease
Kurfürst, Helena ; Doležal, Vladimír (advisor) ; Krištofíková, Zdena (referee)
: Choline is being used in all mammalian cells as a precursor for synthesis of a major phospholipide phosphatidylcholine and as a donor of acetyl residues. Cholinergic neurons in addition require choline to synthesize neuromediator acetylcholine. The ability of cells to create choline via de novo synthesis is limited and therefore they need to transport choline from extracellular space. Limited availability of choline in brain leads specifically to diminished function of cholinergic neurons and in general to impaired reparation of biological membranes. Dysfunctions of cholinergic signaling in brain is characteristic for Alzheimer's disease. Aim of this work was to investigate whether gene and protein expression of high- affinity cholinergic transporters is altered in 5-6 months old APPswe/PS1dE9 mouse model of Alzheimer's disease. Expression of specific high-affinity cholinergic transporter CHT1 (responsible for transport of choline to be used for acetylcholine synthesis) and putative high-afinity choline transporter CTL1 (generally present in all cells and related to high affinity choline transport for phospholipide synthesis) in cerebral cortex was measured. Compared to non-trangenic littermates, no changes in the expression of both genes were detected at either mRNA (quantitative PCR) or protein...
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The use of MR spectroscopy in neurosurgery
Malucelli, Alberto ; Hájek, Milan (advisor) ; Ryznarová, Zuzana (referee) ; Vaverka, Miroslav (referee)
Proton MR spectroscopy is a non-invasive tool for measuring in vivo concentrations of several metabolites. The aim of this thesis was to test its applicability and reliability in neurosurgical praxis. In the first part of the study multiple MR spectroscopy methods were applied in a group of patients after surgery and oncologic treatment for high-grade glioma to test which method performed best in discriminating recurrent tumor from radionecrosis in the presence of a new enhancing lesion. The best diagnostic yield was achieved by comparison of choline, creatine and lactate between lesion and contralateral side (sensitivity 93.3%, specificity 78.6%). Creatine was significantly decreased in patients compared to controls. The inhibiting effect of ongoing oncologic treatment on cerebral and tumoral metabolism makes differential diagnosis trickier. Therefore, a diagnosis of radionecrosis assessed during ongoing radio- and chemotherapy should be confirmed after its completion. In the second part of the study MR spectroscopy data was compared with MR hippocampal volumetry and transcranial doppler examination in a cohort of patients with unilateral occlusion of the internal carotid artery. The N-acetylaspartate/choline ratio and hippocampal volume were significantly lower in both hemispheres of patients...
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Construction and Application of Flow Amperometric Biosensor Based on Enzymatic Reactor for Determination of Choline
Tvorynska, Sofiia ; Barek, J. ; Josypčuk, Bohdan
In this contribution, a novel fast, simple and stable biosensor with the enzymatic reactor based on choline oxidase (ChOx) was developed and applied for the determination of choline using flow injection analysis with amperometric detection. The preparation of the reactor is based on the covalent immobilization of ChOx with glutaraldehyde to mesoporous silica powder (SBA-15) previously covered by NH2-groups. The experimental parameters affecting the sensitivity and stability of the biosensor were optimized. The proposed biosensor with the newly developed ChOx-based reactor possesses good repeatability, reproducibility, long-term stability, and reusability. It was successfully applied for the determination of choline in commercial pharmaceuticals.
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Pleiotropic effects of transcriptional protein Opi1 in Saccharomyces cerevisiae
Pavlíčková, Martina ; Schierová, Michaela (advisor) ; Mašek, Tomáš (referee)
Phospholipid biosynthesis in Sacchromyces cerevisiae is regulated by Ino2p-Ino4p activation complex and Opi1p repressor. The most highly regulated INO1 gene encodes inositol-3- phosphate synthase. This enzyme catalyzes the first step of the metabolic pathway of inositol synthesis. The Ino2p-Ino4p activation complex binds to the promoter of the target genes and interacts with other proteins necessary for activation (Snf1p, SAGA, SWI/SNF, INO80). The Opi1p represses transcription by direct binding to Ino2p and by interaction with other proteins (Sin3p, Cyc8p). The activity of Opi1p protein is mediated by cellular localization and by phosphorylation. The regulation of phospholipids is dependent on the growth phase and on the availability of precursors. Apart from its repressor activity, Opi1p affects mitochondrial metabolism, endoplasmic reticulum stress, cell size, mat formation and invasive growth.
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Gen expresion of high affinity choline transporter in mouse model of Alzheimer's disease
Kurfürst, Helena ; Krištofíková, Zdena (referee) ; Doležal, Vladimír (advisor)
: Choline is being used in all mammalian cells as a precursor for synthesis of a major phospholipide phosphatidylcholine and as a donor of acetyl residues. Cholinergic neurons in addition require choline to synthesize neuromediator acetylcholine. The ability of cells to create choline via de novo synthesis is limited and therefore they need to transport choline from extracellular space. Limited availability of choline in brain leads specifically to diminished function of cholinergic neurons and in general to impaired reparation of biological membranes. Dysfunctions of cholinergic signaling in brain is characteristic for Alzheimer's disease. Aim of this work was to investigate whether gene and protein expression of high- affinity cholinergic transporters is altered in 5-6 months old APPswe/PS1dE9 mouse model of Alzheimer's disease. Expression of specific high-affinity cholinergic transporter CHT1 (responsible for transport of choline to be used for acetylcholine synthesis) and putative high-afinity choline transporter CTL1 (generally present in all cells and related to high affinity choline transport for phospholipide synthesis) in cerebral cortex was measured. Compared to non-trangenic littermates, no changes in the expression of both genes were detected at either mRNA (quantitative PCR) or protein...
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