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Acipimox during Short-Term Exercise Exerts A Negative Feedback of Growth Hormone on Ghrelin Secretion in Patients with Bulimia Nervosa and in Healthy Women: The Role of Lipolysis
Smitka, Kvido ; Nedvídková, Jara (advisor) ; Kršek, Michal (referee) ; Čáp, Jan (referee)
Title: Acipimox during Short-Term Exercise Exerts A Negative Feedback of Growth Hormone on Ghrelin Secretion in Patients with Bulimia Nervosa and in Healthy Women: The Role of Lipolysis Objective: Eating disorders, such as bulimia nervosa (BN) and anorexia nervosa (AN), are characterized by abnormal eating behavior. The main features of BN are binge-eating and inappropriate compensatory methods to prevent weight gain. The appetite-modulating peptide ghrelin is secreted by the stomach and shows a strong release of growth hormone (GH). A potential GH-ghrelin feedback loop between stomach and the pituitary has been recently reported. Acipimox (Aci), an analogue of nicotinic acid, inhibits lipolysis in adipose tissue (AT) and reduces plasma glycerol and free fatty acids (FFA) levels. Exercise and Aci are stimulators of GH secretion. We suppose that a negative feedback from increased GH levels during exercise may play a role in reducing plasma ghrelin levels. We surmised that altered baseline activity and exercise-induced activation of the sympathetic nervous system (SNS) results in excessive stimulation of lipolysis associated with negative energy balance and may lead to abnormal AT metabolism in patients with BN. Disruption of the gut-brain-AT axis might be involved in the pathogenesis of BN. The...
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Solubility control of biodegradable starch-based packaging
Krobot, Štěpán ; Ondreáš, František (referee) ; Lepcio, Petr (advisor)
This bachelor thesis deals with the preparation and testing of biodegradable films based on starch. The aim of the thesis is laboratory preparation of foils based on various types of starch, glycerol, polyvinylalcohol and with the addition of plasticizer – citric acid. Four different types of starch and two types of polyvinyl alcohol were used. In the first series of samples, the ratio of added glycerol to starch content was varied. Samples in the second series were prepared in the same ratios, but with different PVA. A citric acid solution was added into the last series of samples. The second aim of the thesis, after pressing the films, was to determine their solubility and stability in aqueous media depending on the ratio between added glycerol to starch content, the type of polyvinylalcohol used, and the addition of citric acid to the mixture. It has been found that citric acid appears to affect the chemical structure of the films and thus their solubility in aqueous media as well as their mechanical properties. Fourier-transform infrared spectroscopy (FTIR) was used to study the structure of the films and to elucidate its effect on solubility.
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Processing optimalization of biodegradable starch based packaging and its characterization for adaptation on production technology
Krahulová, Veronika ; Ondreáš, František (referee) ; Lepcio, Petr (advisor)
This diploma thesis focuses on the problematics of preparation of biodegradable starch based packaging. The aim of the thesis is to optimize the preparation and verify the characteristics for further adaptation and production technologies. The films consisted of starch, PVA and glycerol. Four types of starches, three types of PVA and different ratios of glycerol were tested. Films were prepared by casting with glycerol as a plasticizer, instead of distilled water, to reduce the energy cost of the preparation. The mechanical properties of the films were tested as well. The experimentally determined values of elongation at break and tensile strength of the wheat starch films were compared with a semiempirical model. Results revealed that the preparation of thermoplasticization of starch with glycerol leads to a considerable increase in elongation at break but at the same time to a marked decrease in tensile strength compared to the preparation from solution. The rheological properties of the prepared films were also investigated. Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the structure of the films.
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Influence of particle size on microreology experiments using fluorescence correlation spectroscopy
Valovič, Stela ; Sedláček, Petr (referee) ; Mravec, Filip (advisor)
This diploma thesis deals with microrheology measured via the fluorescence correlation spectroscopy. As microrheological probes, fluorescently marked nanoparticles of 5 sizes in the range of 10-100 nm, were used. The particles had been immersed in a variety of concentrated glycerol solutions and agarose gels of different concentrations, and the FCS measurement revealed a diffusion coefficient of individual particles in each environment. Based on the coefficient, the viscosity of the glycerol needed to stop the particles could be determined. Particles of 10 nm size were not stopped even by the 100 wt% glycerol. In the case of the agarose gels, a combination of higher agarose concentration and larger particles resulted in an increase in the diffusion coefficient to an unlikely high value. This was caused probably by an agarose autofluorescence and the value indicates stopping of the particles in the given agarose gel. Later, the data acquired by the FCS measurement were converted to MSD curves using MATLAB software. The thesis discusses the influence of the experimental parameters on the shape of the MSD curve. The results showed that the number of particles and autocorrelation function have the most significant effect.
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Production of carotenoids grown on waste fat
Holub, Jiří ; Němcová, Andrea (referee) ; Márová, Ivana (advisor)
Carotenoids are lipid-soluble pigments which are contained in plants and microorganisms. Carotenoids are known for their antioxidant effects. Lipids are predominantly non-polar substances, which are essential and present in all types of organisms. The research was made by theoretical and practical form. It was dealing with production of carotenoids pigments and different lipophilic substances by yeasts of Rhodotorula glutinis, Rhodosporidium toruloides and Sporidiobolus metaroseus, cultivated in media containing waste fat or glycerol. Further, methods for obtaining lipid substances from microorganisms and with further analysis of samples by gas or liquid chromatography were optimized. The main task of the research was to find out which types of media and yeasts are the most suitable for production of lipid substances. For production of lipid substances in glycerol media, as the best producing strain Rhodosporidium toruloides was found, which simultaneously reported the highest concentrations of carotenoids on fatty and fatty hydrolyzed media.
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Use of starch and glycerin in polymer films with controlled life span
Almásyová, Zuzana ; Pospíšil, Ladislav (referee) ; Jančář, Josef (advisor)
This diploma thesis deals with preparation and testing of biodegradable materials for use in the packaging indrustry. The task of this work is to prepare set of laboratory made films based on wheat starch, glycerol, polyvinyl alcohol with the addition of a suitable additive, which has been selected as citric acid. A suitable composition meeting the requirements of the packaging foils has been found. Quaternary blends from all components achieve the best results. It has been found that citric acid can influence the chemical structure and thus affect the mechanical and thermal properities and also the degree of solubility. The films were characterized in terms of mechanical properities by tensile testing and thermal stability by means of thermogravimetric analysis with respect to the phase structure. The structure was characterized by Fourier transform infrared spectroscopy and confocal laser scanning microscopy. The biodegradability of the film was tested by its solubility in aqueous medium.
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Acipimox during Short-Term Exercise Exerts A Negative Feedback of Growth Hormone on Ghrelin Secretion in Patients with Bulimia Nervosa and in Healthy Women: The Role of Lipolysis
Smitka, Kvido ; Nedvídková, Jara (advisor) ; Kršek, Michal (referee) ; Čáp, Jan (referee)
Title: Acipimox during Short-Term Exercise Exerts A Negative Feedback of Growth Hormone on Ghrelin Secretion in Patients with Bulimia Nervosa and in Healthy Women: The Role of Lipolysis Objective: Eating disorders, such as bulimia nervosa (BN) and anorexia nervosa (AN), are characterized by abnormal eating behavior. The main features of BN are binge-eating and inappropriate compensatory methods to prevent weight gain. The appetite-modulating peptide ghrelin is secreted by the stomach and shows a strong release of growth hormone (GH). A potential GH-ghrelin feedback loop between stomach and the pituitary has been recently reported. Acipimox (Aci), an analogue of nicotinic acid, inhibits lipolysis in adipose tissue (AT) and reduces plasma glycerol and free fatty acids (FFA) levels. Exercise and Aci are stimulators of GH secretion. We suppose that a negative feedback from increased GH levels during exercise may play a role in reducing plasma ghrelin levels. We surmised that altered baseline activity and exercise-induced activation of the sympathetic nervous system (SNS) results in excessive stimulation of lipolysis associated with negative energy balance and may lead to abnormal AT metabolism in patients with BN. Disruption of the gut-brain-AT axis might be involved in the pathogenesis of BN. The...
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High-fast electrophoretic determinations of clinically important compounds in body fluids.
Málková, Klára ; Kvasnicová, Vladimíra (referee) ; Bosáková, Zuzana (advisor)
A capillary electrophoretic procedure employing contactless conductivity detection (C4 D) has been developed for direct determination of the glycerol and mannitol polyalcohols in biological and pharmacological samples. Both glycerol and mannitol are fully separated from the sample matrix within very short times of 3.0 and 3.9 min., respectively, when using the optimized background electrolyte, 60 mM H3BO3 + 30 mM LiOH (pH 9.1). The limits of detection amount to 0.5 µM for glycerol and 0.3 µM for mannitol. The repeatability of the glycerol determination in real biological materials is characterized by the coefficient of variation values, 0.5 % and 3.2 %, for the migration time and the peak area, respectively. The procedure has been used to monitor the free glycerol concentration in adipose tissue microdialyzates. A physiological study has demonstrated that the lipolysis occurring during a sporting action can be stimulated by local application of adrenaline. The procedure has further been utilized to determine mannitol in a pharmacological preparation.
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Use of selected fluorescence techniques to study of yeasts and yeast metabolites
Mikheichyk, Nadzeya ; Skoumalová, Petra (referee) ; Márová, Ivana (advisor)
The scope of thesis was the optimization of methods for the study of yeast and their metabolites using flow cytometry and fluorescence microscopy. Red yeasts are characterized by overproduction of carotenoids and lipids, which are used in food, pharmaceutical and feed industries. Currently, intensive research is being carried on to find appropriate microbiological alternatives for synthesis of these substances. Present thesis is focused on selected yeast genera: Rhodotorula, Sporobolomyces, Cystofilobasidium and strain Phaffia rhodozyma. Yeasts were cultivated on different nutrient media, in which glucose was used as a nutritional source, and also on glycerol and whey as waste material. In two strains - Cystofilobasidium macerans and Rhodotorula mucilaginosa growth characteristics were determined on a synthetic glucose production medium. All studied strains were able to use waste substrates as a source of nutrients. Some of the strains displayed increased production of carotenoids, and, additionally, in some cases also relatively high production of lipids. In classical cultivation in lipid and glucose medium supplemented with vitamins the best production characteristics displayed Rhodotorula glutinisstrain. In glycerol medium the highest amount of carotenoids and lipidic substances produced Sporobolomyces shibatanus strain. Strain Sporobolomyces roseus showed the best production characteristics on whey as the main source of carbon. The results show use of whey and glycerol seems like appropriate option for potential carbon source to cultivate carotenogenic yeasts and production of carotenoids and selected lipidic substances as products with higher added value. Further optimization of nutrient medium on the given substrates is needed for higher production of selected metabolites. Fluorescence microscopy and flow cytometry have proved to be suitable options for determination of the observed metabolites in the cells, their amount and viability.
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