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Effect of triclosan on in vitro meiotic maturation of porcine oocytes
Straková, Johana ; Petr, Jaroslav (advisor) ; Frolíková, Michaela (referee)
Meiotic maturation of oocytes is a key phase in the development of female gametes. The natural physiology of oogenesis and meiotic maturation is currently being influenced by a number of anthropogenic environmental contaminants. These compounds include triclosan. Triclosan (5- chloro-2-(2,4-dichlorophenoxy) phenol) is an antibacterial substance commercially used in cosmetic and disinfectant products. This compound enters the human body by absorption through the skin and mucous membranes. Its presence has been demonstrated in blood, urine, breast milk, liver and adipose tissue. Triclosan is classified as an endocrine disruptor, yet its consumption continues to increase worldwide. The aim of this study is to evaluate the effect of low doses of triclosan on selected markers of meiotic maturation of porcine oocytes in vitro. This work describes the negative effects of triclosan and triclosan in combination with bisphenol S on the meiotic maturation of porcine oocytes in vitro. Furthermore, the effect of these substances on the increased percentage of abnormal meiotic spindles and the stability of the microtubules of the meiotic spindle was demonstrated. Effects on mitochondria and epigenetic effects of triclosan were not proved. The results highlight the risks associated with the commercial use of...
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Construction of an electrochemical cell based on carbon film electrode
Libánský, Milan ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
This Thesis deals with the construction of an electrochemical cell with two types of integrated composite electrodes based on carbon films. Using these electrodes, the voltammetric behavior of environmental pollutant triclosan (5-chlor-2-(2,4- dichlorophenoxy)phenol) was studied. For the construction of composite electrodes, graphite and glassy carbon were used as conductive microparticles. Several types of polymers served as the nonconductive binder. For the measurements, combinations of graphite with polystyrene and graphite with polycarbonate were selected as optimum materials. From the dependence of peak heights on solution composition, a mixture of a buffer of pH 7 and methanol (1:9, V/V) was selected as the optimum medium. In this medium, concentration dependences were measured; calculated triclosan detection limit were 0,49 µmol dm-3 for carbon polystyrene composite electrode and 0,25 µmol dm-3 for carbon polycarbonate composite electrode, respectively. The possibility of further increasing the sensitivity of the determination by the accumulation step was studied. Accumulation of triclosan on carbon polystyrene composite electrode was observed, but the increase in response was connected with the loss of repeatability. Accumulation of triclosan on carbon polycarbonate composite electrode was...
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Optimalization and validation of method for electrochemical determination of triclosan
Vránová, Edita ; Dejmková, Hana (advisor) ; Fischer, Jan (referee)
In this thesis were, on the basis of earlier work, examined some of the conditions for the determination of triclosan by differential pulse voltammetry using carbon paste electrode and miniaturized carbon paste electrode. Phosphate buffer pH 11 was chosen as the most suitable medium of three supporting electrolytes with pH 11 and 12. The possibility of suppression of electrode passivation by addition of triton X-100 was studied. In addition, the validation parameters were searched, which included limits of detection, linearity of the concentration dependence, repeatability, and accuracy of the method. From these parameters, applicability of the method and the particular electrodes was assessed. Under the selected optimal conditions calibration curves for deionized, river and drinking water were measured. Detection limit with carbon paste electrode, was determined for deionized water to 120 ppb, for drinking water to 140 ppb and for river water to 90 ppb. The detection limit with miniaturized carbon paste electrode, was determined for the deionized water to 110 ppb , for drinking water to 130 ppb and for river water to 140 ppb. The linearity of the calibration curve was evaluated using the correlation coefficient. The samples of drinking and river water were then measured using carbon paste...
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Construction of an electrochemical cell based on carbon film electrode
Libánský, Milan ; Zima, Jiří (advisor) ; Fischer, Jan (referee)
This Thesis deals with the construction of an electrochemical cell with two types of integrated composite electrodes based on carbon films. Using these electrodes, the voltammetric behavior of environmental pollutant triclosan (5-chlor-2-(2,4- dichlorophenoxy)phenol) was studied. For the construction of composite electrodes, graphite and glassy carbon were used as conductive microparticles. Several types of polymers served as the nonconductive binder. For the measurements, combinations of graphite with polystyrene and graphite with polycarbonate were selected as optimum materials. From the dependence of peak heights on solution composition, a mixture of a buffer of pH 7 and methanol (1:9, V/V) was selected as the optimum medium. In this medium, concentration dependences were measured; calculated triclosan detection limit were 0,49 µmol dm-3 for carbon polystyrene composite electrode and 0,25 µmol dm-3 for carbon polycarbonate composite electrode, respectively. The possibility of further increasing the sensitivity of the determination by the accumulation step was studied. Accumulation of triclosan on carbon polystyrene composite electrode was observed, but the increase in response was connected with the loss of repeatability. Accumulation of triclosan on carbon polycarbonate composite electrode was...
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