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Influence of cholesterol concentration on permeability and microstructure of model skin barrier lipid membranes
Červená, Martina ; Vávrová, Kateřina (advisor) ; Zbytovská, Jarmila (referee)
Cholesterol is a substance of a steroidal nature that has a number of functions in the human body. One of them is also an irreplaceable role in the proper functioning of the skin barrier. Cholesterol is an integral part of the lipid matrix, together with ceramides and free fatty acids in an equimolar ratio (1: 1: 1), and 5% cholesterol sulfate, which fills the intercellular space between stratum corneum cells and is responsible for the barrier properties of the skin. Cholesterol is therefore necessary for epidermal homeostasis, but its role in SC permeability is unknown. The aim of this work was to study the influence of cholesterol concentration on the permeability and microstructure of model lipid membranes of the skin barrier. Eight sets of model membranes with decreasing cholesterol concentrations (100%, 80%, 70%, 60%, 40%, 20%, 0%) and cholesterol alone were studied for which permeability and microstructure were monitored.The study of permeability of membranes was carried out in the Franz diffusion cells by measuring four permeation parameters: water loss, electrical impedance measurement, and the cumulative amount of two model drugs (theophylline and indomethacin). The microstructure of these model membranes was verified by X-ray powder diffraction. X-ray powder diffraction measurements...
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Development of electroanalytical methods for detection of cholesterol, 7-dehydrocholesterol and cholecalciferol
Benešová, Lenka ; Schwarzová, Karolina (advisor) ; Navrátil, Tomáš (referee) ; Šelešovská, Renáta (referee)
Steroidival substances are an integral part of the human organism, such as bile acids, steroid hormones, vitamins. The most important sterol in whole organism is cholesterol, which is cornerstone of the all cell membranes. It is involved in important processes in the body, but its storage in blood vessels in the formo f low-density lipoprotein (LDL) is crucial of reason serious health diseases as atherosclerosis, myocardial infarction and others. 7-dehydrocholesterol is a precursor of cholesterol and another sterol compound studied by me, cholekalciferol, also known as a vitamin D3. Deficiency of 7-dehydrocholesterol reductase is the main indicatior of the possible genesis of Smith-Lemli-Opitz syndrome. One of the goals of this thesis was developed a suitable electrochemical method to facilitate the diagnosis of this syndrome from plasma and amniotic fluid in the prenatal and postnatal phases of pregnancy. Within the framework of this thesis were developer electrochemical methods in a batch and flow arrangement for detection of the above-mentioned sterols, namely cholesterol, 7-dehydrocholesterol and cholekalciferol. It was wokered in the medium contain perchloric acid or its salt sodium perchlorate in acetonitrile as supporting electrolyte. It was worked in the wide range of working disc...
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The role of cholesterol in the pathogenesis of Alzheimer's disease
Tax, Martin ; Rudajev, Vladimír (advisor) ; Randáková, Alena (referee)
Alzheimer's disease is a neurodegenerative disorder and the most common form of dementia affecting a significant part of the aging population. It seems that the main cause of this disease is the accumulation of amyloid β (Aβ). Cholesterol is an important component of plasma membranes where it is essential for proper synapse function. Changes in its concentration are considered to be a risk factor for the onset and development of Alzheimer's disease. Data show that this lipid has an effect on Aβ synthesis and also has a role in Aβ cytotoxicity where it may promote the negative properties of Aβ or on the contrary can be protective against them.
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Determination of cholesterol, 7-dehydrocholesterol and cholecalciferol by HPLC with spectrophotometric and electrochemical detection
Dostálková, Lucie ; Schwarzová, Karolina (advisor) ; Vyskočil, Vlastimil (referee)
The aim of this thesis is to verify the possibility of simultaneous determination of three structurally related biologically active substances (cholesterol, 7-dehydrocholesterol and cholecalciferol) after previous separation by high-performance liquid chromatography followed by electrochemical (on a boron-doped diamond electrode) and spectrophotometric detection, which were compared in this work. The influence of the water content in the mobile phase (in the range of 0-10 %) on the retention factor of the analytes and their response for both types of detectors was investigated. Using all mentioted water contents, the analytes baseline-separated. As the water content increased, the retention factor of the analytes increased as well as the background current for higher positive detection potentials. Based on the recorded hydrodynamic voltammograms, the optimum detection potential + 1.8 V was chosen. The optimum wavelength for spectrophotometric detection was 200 nm. The concentration dependence was measured in an of 50 mmol l−1 sodium perchlorate in acetonitrile mixed with water (95:5, v/v). The spectrophotometric detector provided lower detection limits compared with the electrochemical detector, which had detection limits of 2.3 μmol l−1 for cholesterol, 1.4 μmol l−1 for 7-dehydrocholesterol and...
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Solid form of liposomal systems for inhalation
Fardová, Lucie ; Kalina, Michal (referee) ; Mravec, Filip (advisor)
This thesis deals with the preparation of solid liposomal systems for inhalation delivery. Liposomal systems were prepared by rehydration of a phospholipid film from dipalmitoylphosphatidylcholine. A sucrose solution used for film rehydration served as a protectant during spray drying. Additional liposome samples contained cholesterol, phosphatidic acid, or polyethylene glycol for better stabilization. The prepared liposome solutions were examined using scanning transmission electron microscopy, dynamic light scattering, and electrophoretic light scattering methods. Dried powders were measured using infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and determination of particle aerodynamic size. The results demonstrate the successful preparation of all liposomal systems, their drying into powder form, and subsequent reconstruction after rehydration with water or buffer. Based on the observed properties, liposomes with polyethylene glycol appeared to be the most suitable.
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Nasycené mastné kyseliny v rostlinných olejích: zdroje a vliv na lidské zdraví
Jašková, Jana
This bachelor thesis deals with vegetable oils that contain a higher proportion of saturated fatty acids. The aim was to determine their sources and impact on human health. This is a literature search that describes the classification of saturated fatty acids among lipids and informs about the most important saturated fatty acids. It also defines the most common vegetable oils with predominant stearic, palmitic or lauric acid. Last but not least, it describes their cultivation and subsequent processing into oil production. At the end of the thesis, diseases associated with saturated fatty acids are formulated, especially the increase in the level of LDL cholesterol and its effect on human health. Overall, the topic of lipids and saturated fatty acids has not been fully explored and contradictory studies are emerging on how they affect human health and how they should be reduced in the human diet.
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Subcellular insight into cholesterol-mediated proliferation of the tick cell line
KROPÁČKOVÁ, Sára
Arthropods, including ticks, are not able to synthetise cholesterol de novo. However, cholesterol is an essential component of their cell membranes and serves as a precursor for the synthesis of steroid hormones. In this thesis, I looked at the biological function of exogenous cholesterol on the tick Ixodes ricinus cell line IRE/CTVM19. I verified the need for cholesterol supplementation in the growth medium for proper cell proliferation. Cellular proliferation was stimulated by cholesterol and not by other sterols (ergosterol, sitosterol). We further explored the two assumed aforementioned cholesterol cellular roles, but also investigated the role of cholesterol as a signal molecule: The effect of cholesterol sensing is described on the tick cell level, as well as on the level of the whole organism, using the ex vivo feeding system of ticks. This work provides novel insights into the cholesterol biology of ticks and tick cells, increasing our understanding of tick-host blood molecules' interaction.
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Voltammetric behaviour of cholesterol and lanosterol on boron doped diamond electrode
Kubešová, Jana ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this thesis is to investigate procedures leading to regeneration of boron- doped-diamond's (BDD electrode) surface and study of voltammetric behaviour of cholesterol and lanosterol on BDD electrode. Three options of regeneration of electrode's surface were were studied: the stirring, the mechanical polishing using alumina and the anodic oxidation. The anodic oxidation was studied using electrolytes: 0,1 mol l−1 perchloric acid in acetonitrile, 0,1 mol l−1 sodium perchlorate in acetonitrile and tetrahexylammonium hexafluorofosphate in acetonitrile. Each electrolyte was studied with 0 or 0,43 % and 20 % volume of water. Further, voltammetric behaviour of cholesterol on BDD electrode in the presence of 0,1 mol l−1 perchloric acid in acetonitrile was investigate. The second part of the thesis was the study of voltammetric behaviour of lanosterol on BDD electrode in the presence of 0,1 mol l−1 perchloric acid in acetonitrile and 0,1 mol l−1 sodium perchlorate in acetonitrile. The study was performed using cyclic voltammery. Lanosterol provides two anodic signals in the presence of both electrolytes, the first one at the potential of +1200 mV, the second one at the potential of +1500 mV. The stability of lanosterol in the presence of perchloric acid and sodium perchlorate was studied by...
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