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A new approach to the electroanalysis of primary bile acids and related steroids
Klouda, Jan
In this doctoral thesis, a novel method for the determination of primary bile acids cholic acid and chenodeoxycholic acid is presented. Bile acids play various vital roles in the mammalian body. Moreover, their determination is extremely helpful in liver and biliary disease diagnosis and management. These saturated organic compounds lack strong chromophores and fluorophores in their structure, and thus are usually hard to detect in spectroscopy. For this reason, either instrumentally advanced but expensive methods, such as mass spectrometry, or less reliable enzymatic methods are commonly employed in bile acids quantitation. Hence, the demand for simple and reliable methods for their determination is strong. Bile acids are also known to be virtually inert for direct electrochemical oxidation. Herein, a simple method for their chemical activation for electrochemical oxidation on bare electrode materials was developed, optimized and applied to cholic acid and chenodeoxycholic acid determination. The activation is based on a dehydration reaction of a primary bile acid with 0.1 mol L-1 HClO4 in acetonitrile (water content 0.55%) that introduces double bond(s) into the originally fully saturated steroid core. This naturally increases the electron density in the structure, and thus allows electrochemical...
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A new approach to the electroanalysis of primary bile acids and related steroids
Klouda, Jan
In this doctoral thesis, a novel method for the determination of primary bile acids cholic acid and chenodeoxycholic acid is presented. Bile acids play various vital roles in the mammalian body. Moreover, their determination is extremely helpful in liver and biliary disease diagnosis and management. These saturated organic compounds lack strong chromophores and fluorophores in their structure, and thus are usually hard to detect in spectroscopy. For this reason, either instrumentally advanced but expensive methods, such as mass spectrometry, or less reliable enzymatic methods are commonly employed in bile acids quantitation. Hence, the demand for simple and reliable methods for their determination is strong. Bile acids are also known to be virtually inert for direct electrochemical oxidation. Herein, a simple method for their chemical activation for electrochemical oxidation on bare electrode materials was developed, optimized and applied to cholic acid and chenodeoxycholic acid determination. The activation is based on a dehydration reaction of a primary bile acid with 0.1 mol L-1 HClO4 in acetonitrile (water content 0.55%) that introduces double bond(s) into the originally fully saturated steroid core. This naturally increases the electron density in the structure, and thus allows electrochemical...
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Drinking regime in terms of evidence based medicine
Pihera, Jan ; Procházka, Michal (advisor) ; Vitujová, Marie (referee)
Bachelor thesis "Drinking regime in terms of evidence based medicine" is focused on complex take on the topic of fluid intake based on current knowledge and most recent studies. The content of this work consists of body water function and hydration theoretical summary. Based on this summary is experimental part which should confirm the relationship between hydration and performance.
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Development of voltammetric methods for detection of phytosterols on carbon-based electrodes
Zelenský, Michal ; Schwarzová, Karolina (advisor) ; Fischer, Jan (referee)
The aim of this diploma thesis was to develop an electrochemical method for three phytosterols, namely stigmasterol β-sitosterol and ergosterol using voltammetry techniques on glassy carbon electrode and boron doped diamond electrode. The work builds on previous results, where it was shown that the electrochemical oxidation of phytosterols requires perchloric acid in acetonitrile. When this acid is used, a dehydration reaction occurs. Calibration dependences were measured here for all phytosterols in an environment with a water content of 0.43%. The stability of the signal with increasing distilled water content was further investigated. Then the calibration dependences in the increased water content were measured again. If we want to use HPLC-type separation techniques, we must first find out how the phytosterols will behave in this environment, and therefore the signal stability on the buffer content was investigated. The buffers used were phosphate and acetate buffer. Subsequently, the concentration dependence was measured in an environment with a higher content of phosphate buffer. Furthermore, the possibility of detecting two phytosterols at once was investigated. Key words: dehydration, glassy carbon electrode, boron doped diamond electrode, oxidation, phytosterols, voltammetry
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Development of electroanalytical methods for detection of bile acids possessing 7α hydroxyl group
Jelšíková, Kristýna ; Schwarzová, Karolina (advisor) ; Dejmková, Hana (referee)
This master's thesis contains a study of electrochemical processes of selected bile acids possessing 7 hydroxyl group (cholic, chenodeoxycholic and −muricholic). The measurements were performed on boron−doped diamond electrode in the non-aqueous medium of acetonitrile and perchloric acid (water content 0.55 %) by cyclic voltammetry. It is known that the electrochemical activity of 7 bile acids is increased by a dehydration reaction between perchloric acid and the 7 bile acid. The subject of the study was the stability of the voltammetric response of chemically activated bile acids in the region of negative potentials. It was found that the presence of oxygen in the measured solution is an important factor for obtaining the cathodic signal of 7 bile acids. It probably performs a regenerative function; the product of the electrochemical reduction is re-oxidized in its presence, which leads to an increase in the voltammetric response. At the same time, it is important that the direction of the scan in cyclic voltammetry first proceeds to positive values. A potential of +2.0 V (vs. Ag/AgNO3 in acetonitrile) must be reached for the HO● radicals to be formed. It is these radicals that presumably lead to the formation of the product(s) of bile acids electrochemical oxidation that can be subsequently...
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A new approach to the electroanalysis of primary bile acids and related steroids
Klouda, Jan ; Schwarzová, Karolina (advisor) ; Skopalová, Jana (referee) ; Vyskočil, Vlastimil (referee)
In this doctoral thesis, a novel method for the determination of primary bile acids cholic acid and chenodeoxycholic acid is presented. Bile acids play various vital roles in the mammalian body. Moreover, their determination is extremely helpful in liver and biliary disease diagnosis and management. These saturated organic compounds lack strong chromophores and fluorophores in their structure, and thus are usually hard to detect in spectroscopy. For this reason, either instrumentally advanced but expensive methods, such as mass spectrometry, or less reliable enzymatic methods are commonly employed in bile acids quantitation. Hence, the demand for simple and reliable methods for their determination is strong. Bile acids are also known to be virtually inert for direct electrochemical oxidation. Herein, a simple method for their chemical activation for electrochemical oxidation on bare electrode materials was developed, optimized and applied to cholic acid and chenodeoxycholic acid determination. The activation is based on a dehydration reaction of a primary bile acid with 0.1 mol L-1 HClO4 in acetonitrile (water content 0.55%) that introduces double bond(s) into the originally fully saturated steroid core. This naturally increases the electron density in the structure, and thus allows electrochemical...
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Voltammetric behaviour of cholesterol on glassy carbon electrode
Bláhová, Eva ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
The aim of this Thesis is a study of voltammetric behaviour of cholesterol on glassy carbon electrode in the presence of acetonitrile and strong acid. The electrochemical oxidation occurs after dehydration of cholesterol induced by the acid. The study was performed using cyclic voltammetry, mostly in the presence of perchloric acid. Further, influence of other acids - sulphuric, nitric and phosphoric acid - was studied. Cholesterol provides in the presence of perchloric and sulphuric acid one anodic signal at the potential of +1400 mV vs. Ag/0,01 mol.l-1 AgNO3 in 1 mol.l-1 NaClO4 in acetonitrile. The influence of polarization rate, water content and concentration of perchloric acid in the supporting electrolyte on the oxidation signal of cholesterol was studied. Calibration dependence of cholesterol was measured using differential pulse voltammetry. The limit of detection was determined to be 4,83.10-6 mol.l-1 . Key words: Dehydration, glassy carbon electrode, cholesterol, oxidation, voltammetry
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Pre-competition reduction of body weight in MMA
Hrdlička, Jaroslav ; Coufalová, Klára (advisor) ; Pavelka, Radim (referee)
Title: Pre-competition reduction of body weight in MMA Objectives: The main aim of this work was to identify what weight reduction methods are used by professional MMA fighters and how many kilograms they reduce before fights. We also wanted to determine the time they start to work with their body weight and whether they feel any psychological changes or fatigue due to weight reduction. We were also interested in what supplements fighters use during weight cut. Methods: A survey method was used for data collection. The research sample consisted of 20 professional MMA fighters between the ages of 18 and 40. Results: We have found out that MMA fighters usually reduce their weight through reduced caloric intake and subsequent dehydration the most. The majority of respondents reported a reduction of 6 to 10 kilograms in the course of 2 to 4 weeks before the fight. Respondents feel weakened during weight loss and experience psychological impacts such as irritation, mood swings, aggression and sedation. Before the fight, 60% of fighters do not experience any signs of weakness, as the time period from weighting to the fight itself is sufficient to allow them to regenerate. The most commonly used supplements during weight loss are BCAAs, fat burners, proteins, multivitamins and multiminerals. Keywords:...
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Drinking regime of school age children
NOVÁČKOVÁ, Martina
Nowadays the topic of drinking regime is much discussed. Drinking regimen should supplement the daily loss of fluid in the body, because the human body is 60 % of the water. Water is very important to our human body and has many functions, such as biochemical reactions, heat, nutrient and oxygen distribution. Three goals have been set for this work. The first goal of the work is to map the total amount of fluid received per day. The second goal is total sugar intake during the day and the last goal is to evaluate the most consumed beverages. The thesis is divided into two parts, theoretical and practical. The theoretical part remains the influence of fluids on the child's organism, the principles of drinking regime, dehydration and hyperhydration. The research was processed using a recording sheet that mapped fluid intake 24 hours a day. He also followed the most popular drinks (sweet drinks and mineral waters), types of fruit juices, types of tea and types of milk. Research suggests that one-third of them had the right fluid intake and low intake on the first day. The next day, two-thirds had the right income and one-third the low income. The third, fifth, sixth, seventh day had four-fifths of the correct income and one-fifth the low income. On the fourth day, one half had both the right and the low income. On the eighth day, two-thirds had the right income and one-half the low income. Popular sweet drinks included Coca-Cola, Fanta and the least popular Kofola, Sprite. Mineral water is Poděbradka Prolinie and Korunní is the least popular. The favorite tea was the fruit tea and at least rosehip tea. Most of them consumed whole milk and the least fat. Respondents recommended the recommended daily dose at 5 days, the other days were normal.
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