National Repository of Grey Literature 379 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
Sample preparation for analyzing oligomeric forms of amyloid beta by mass spectrometry
Mrkvičková, Simona ; Cvačka, Josef (advisor) ; Kozlík, Petr (referee)
Alzheimer's disease is the most widespread chronic and progressive neurodegenerative disease. The main problem of the disease is the reduction and damage of nerve cells. This leads to loss of brain mass and memory impairment. The disease mainly affects the elderly, for whom it is the most common cause of dementia. Around 50 million people suffer from this disease worldwide, and the number is growing. Alzheimer's disease thus represents a serious public health problem. The pathogenesis of this disease is controlled by the production and deposition of amyloid beta peptide. This peptide tends to aggregate. Its lower oligomeric forms are water-soluble and have a toxic effect on nerve cells. Amyloid beta oligomers therefore represent a possible target for the diagnosis of Alzheimer's disease. Oligomeric forms of beta amyloids have a non-covalent character, which can negatively affect their stability during analyzes in model and biological samples. In this bachelor thesis, suitable conditions for the preparation of model amyloid beta samples were sought. It was observed how the distribution of oligomeric forms changes under the influence of solvents, salts and other additives. The effect of pH on the incubation of amyloid beta in ammonium acetate and water was also investigated. Finally, a method for the...
Determination of essential oils in hops and beer by GC-MS method
Přikryl, Jaroslav ; Sobotníková, Jana (advisor) ; Nesvadba, Vladimír (referee)
The submitted master's thesis aims to the analysis of hop essential oils using gas chromatography separation and subsequent determination using a pair of mass and flame ionization detectors. In the first part, the thesis focuses on the theoretical approach to the issue of hop essential oils and the technical functionality of the device for the detection and quantitative determination of essential oils. Subsequently, in the second part, work describes the development, optimization and validation of the newly developed method for the extraction and determination of hop essential oil.
The development of new isotope-coded cross-linkers for label free quantification of proteins
Procházková, Valérie ; Kukačka, Zdeněk (advisor) ; Vaňková, Pavla (referee)
Elucidating the structure of proteins in living organisms is an important step in describing their role. One method of structural biology is chemical cross-linking in combination with mass spectrometry, which is a commonly used tool for characterisation of the tertiary structure of proteins or protein-protein interactions. This method is based on the reaction of a cross-linking agent consisting of two reactive groups linked by an arm of a defined length to form a covalent bond. The main aim of the project was to verify whether chemical cross-linking using istopically labeled cross-linking agents can be used for quantification of two different structural states. The reagents used in this work were DSPU and an isotopically labeled form of DSPUx. Both the DSPU and DSPUx reagents contain a labile urea molecule in their structure, which is cleaved into characteristic fragments during collision-induced dissociation, allowing the identification of cross-linked peptides. Using top-down and bottom-up approaches, it was found on selected proteins (insulin, human carbonic anhydrase, and bovine serum albumin) that DSPU and DSPUx reagents interact with selected peptides and proteins and are suitable for quantification of structural changes. Subsequently, structural differences in the presence (holoform) and...
Use of separation and mass spectrometric techniques in the diagnosis of Alzheimer's disease
Lebertová, Lucie ; Cvačka, Josef (advisor) ; Kozlík, Petr (referee)
This thesis focuses on the preparation of covalently cross-linked oligomeric forms of amyloid beta and their analysis by SDS-PAGE and MALDI-TOF. The covalently cross-linked oligomeric forms of Aβ(1-42) were formed by chemical and enzymatic reactions. The chains of amyloid beta are crossed over the amino acid residue of tyrosine to form a covalent bond. Such covalent cross-linking stabilizes the oligomeric structure, which allows for improved analysis of amyloid beta oligomers. The development of methods for the detection and quantification of amyloid beta oligomers may be of considerable benefit for the diagnosis of Alzheimer's disease, as it is the oligomeric forms of amyloid beta that are most strongly associated with Alzheimer's disease pathology. In the theoretical part, Alzheimer's disease is described with the above-mentioned problems in early diagnosis and therapy. In addition, background information on amyloid beta is given, and analytical methods for the separation and detection of amyloid beta used in research are described. The experimental part deals with the optimization of analytical methods MALDI-TOF and SDS-PAGE. In the MALDI-TOF, 2,5-dihydroxybenzoic acid and sinapic acid matrices were selected as suitable matrices for the determination of Aβ(1-42). The most suitable method of...
Phytochemical studies of potential phytopharmaceuticals using separation methods
Dulendarova, Elizabeta Hristiyanova ; Jenčo, Jaroslav (advisor) ; Křoustková, Jana (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department: Department of Pharmacognosy and Pharmaceutical Botany Candidate: Elizabeta Hristiyanova Dulendarova Supervisor: RNDr. Jaroslav Jenčo, Ph.D. Title of dissertation thesis: Phytochemical Studies of Potential Phytopharmaceuticals using Separation Methods The main aim of this diploma thesis was the identification of main alkaloidal components from the fraction of Papaver rhoeas L. (family Papaveraceae) alkaloidal extract - fraction PR-12-23. The introduction to the theoretical part summarizes alkaloids found in Papaver rhoeas L. and describes the separation methods used in the isolation process at the department of Phamacognosy and Pharmaceutical botany. Two main compounds within the extract were identified and separated based on HPTLC, HPLC-MS, and GC-MS chromatographic separation methods. For the subsequent fractions, the HPLC method development, optimization, and scaling up from analytical to preparative scale was done. After identification with the help of analytical HPLC and GC, the compounds were separated into fractions, isolated using preparative HPLC, and identified using NMR. The purified isolates were tested for anti-butyrylcholinesterase and cytotoxic biological activity, linked to AD and cancer, respectively. The first...
Analysis of drugs in the earthworms using the QuEChERS method
Navrkalová, Jitka ; Kučerík, Jiří (referee) ; Mravcová, Ludmila (advisor)
The content of this Bachelor‘s thesis is an analysis of pharmaceuticals in earthworms using the QuECHERS method followed by the LC-MS/MS analysis. The theoretical part focuses on the specific groups of used drugs, their properties and applications. Furthermore, it focuses on the occurrence of drugs in the environment from their input to the negative consequences including the impact on earthworms. The theoretical part also discusses the QuEChERS method and liquid chromatography with mass spectrometry. At first in the experimental part, the QuEChERS method (concretely parameters like organic solvent, aqueous phase composition, amount of EDTA, purification method) was optimized for the extraction of 31 drugs from earthworms analytically completed by LC MS/MS. This optimized and validated method is subsequently applied to the extraction of drugs from earthworms from the performed experiments. The experiments focus on the effect of drug concentration in soil and the presence of biochar on the uptake of different drugs by earthworms.
Influence of water vapor on electrical discharge initiated processes in prebiotic atmospheres
Moravčík, Marek ; Chudják, Stanislav (referee) ; Krčma, František (advisor)
The aim of this work is to study the influence of water molecules on chemical processes initiated by electrical discharges in probiotic atmospheres. This work is focused on the simulation of nitrogen atmosphere and carbon dioxide atmosphere. These gases were chosen because they represent the main components of some known atmospheres (N2 the moon Titan, CO2 the planet Mars). A glow discharge generated in a special reactor at atmospheric pressure and a flow of pure N2 or CO2 was used for the simulation. Part of the measurement took place only in pure gas, into which water vapor with a flow rate of 0, 5, 10, 15 and 20 sccm was gradually introduced. In the second part of the measurement, the influence of admixtures was studied. In the case of an N2 atmosphere, methane flow rates of 2 and 4 sccm were used. In the case of an atmosphere with CO2, the nitrogen flow is 2 and 4 sccm. Again, the analysis of the effect of water was carried out for all created atmospheres. The products formed were analysed using proton ionization mass spectrometry and a time-of-flight analyser. Simple aliphatic hydrocarbons, alcohols, aldehydes and ketones were detected. As the number of additives increased, more complex aromatic substances were also formed. At the same time, plasma diagnostics was carried out using optical emission spectroscopy.
Role of antioxidant defense in the synthesis of antidiabetic lipokines
Domanská, Veronika ; Kuda, Ondřej (advisor) ; Zouhar, Petr (referee) ; Vrkoslav, Vladimír (referee)
Fatty acid esters of hydroxy fatty acids (FAHFAs) are a recently discovered group of lipokines consisting of a fatty acid attached to a hydroxy fatty acid with an ester bond resulting in a diverse group of compounds with many different biological activities. Antidiabetic and anti-inflammatory activities are the most studied. The thesis aimed to study this group of bioactive lipids to elucidate the metabolism of FAHFAs and describe the role of antioxidant defense, namely peroxiredoxin 6 (Prdx6), in their biosynthesis with the help of isotopic labeling together with in vitro and in vivo experiments. All the samples, including white adipose tissue, liver, and even human breast milk, were subjected to untargeted or targeted lipidomic and metabolomics analysis using LC-MS/MS. We used the data from isotopically labeled experiments to describe the role of 5-PAHSA in glucose uptake and to show which specific pathways are stimulated by 5-PAHSA administration and which by insulin to compare the effect of both antidiabetic agents. In our samples, we analyzed TAG estolides, which function as intracellular reservoirs of FAHFAs, and managed to describe the role of specific lipases in their metabolism. We reported the role of Prdx6 and the specific enzymatic activity involved in synthesizing precursors that could...
Analytical approaches to study group interactions of azole pesticides with important biological active compounds
Kovač, Ishak ; Jaklová Dytrtová, Jana (advisor) ; Száková, Jiřina (referee) ; Navrátil, Tomáš (referee)
This dissertation presents a developed capillary electrophoresis method for analysing residues of triazole fungicides (TAF) from real samples ("Sweet cherry" tomato - Solanum lycopersicum L) and shows its potential application in environmental analysis. The developed method was validated in-house and characterised by a relatively short analysis time and low cost with sufficient LOD and LOQ. As an additional part of this dissertation, which rose from the tomato plants' treatment with TAF, we studied the impact of triazole fungicides on plant development and their impact on biologically active compounds. Determination of TAF residues from tomato peel carried out with capillary electrophoresis. Capillary electrophoresis is a versatile technique with minute amounts of sample required, with high efficiency in separating small molecules, such as selected TAF. The developed method, cyclodextrin-modified micellar electrokinetic chromatography, accomplished a baseline separation of the TAF mixture from tomato peel. The optimal conditions for separation were in the background electrolyte comprised of phosphoric acid and Tris (100 mM concentration, respectively), 20% v/v methanol, with apparent p[H+ ] 4.8. The constituents of the mixed micellar pseudo-stationary phase were ionic detergent sodium dodecyl...
Vývoj, optimalizace a validace analytické metody na stanovení kyseliny chikorové a dalších derivátů kyseliny kávové pomocí LC/MS
PAZDERKOVÁ, Nela
This thesis deals with the development, optimization, and validation of an analytical method for the determination of chicoric acid and other caffeic acid derivates using LC/MS. First, the development and optimization of the analytical method was conducted. The following parameters were selected for the optimization: mobile phase composition and flow rate injection volume capillary temperature, voltage S-lens and F-lens voltage, ion injection time, product ion selection, and collision energy. Then, the analytical method was successfully validated and tested for quantitative analysis in a range of Echinacea food matrixes - tea, tablet, and tincture.

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