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Artificial phospholipid membranes as models of real membranes and transport of charged particles across them
Parisová, Martina ; Navrátil, Tomáš ; Šestáková, Ivana ; Kohlíková, E. ; Petr, M.
Because the real bio-membranes and the tranporting processes realized across them are very complicated, the model membranes have been used for elucidation of the basic transporting steps. In the contribution, the different possibilities of characterization, description, and elucidation of the transport processes on the example of some metal ions and theor complexes, i.e., of cadmium, lead, and copper, were presented. It summarizes the results achieved using supported phospholipid model membranes formed on porous membranes and on agar support. Discussed transporting processes of selected ions have been characterized using two electrochemical methods: electrochemical impendance spectrometry (EIS) and voltammetry. The impact of some parameters on these systems and processes was investigated.
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Voltammetric determination of anticancer drug flutamide at screen-printed carbon electrodes
Vyskočil, V. ; Navrátil, Tomáš ; Barek, J.
Flutamide, 4-nitro-3-trifluoromethyl-isobutylanilide, is the active component of a synthetic nonsteroidal antiandrogen drug, which is commonly used in the treatment of advanced prostate cancer. In this contribution, optimum conditions have been found vor voltammetric determination of flutamide by DC voltammetry (DCV) and differential pulse voltammetry (DPV) at screen-printed carbon electrodes (SPCEs). Under optimum conditions (Britton-Robinson buffer pH 7.0 - methanol (9:1)), linear calibration curves were measure with limits of quantification 6x10(-7) molL(-1) and 8x10(-7) molL(-1) for DCV at SPCEs, respectively. The newly developed methods were successfully applied to the determination of the drug in pharmaceutical formulation Apo-Flutamide (Eulexin tablets).
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Bioimpedance methods to measure somatometric and volumetric changes
Petr, M. ; Kohlíková, E. ; Navrátil, Tomáš
Assessment of human body composition has stimulated the need for an understanding of available methodologies of estimating fat free mass and percent body fat. In our study, we found statistical significant changes of body composition evaluated by multi-frequency bioelectrical analysis in a group of athletes following creatine supplementation. These results are consistent with literature i.e. supplemented creatine effects osmolality of cell´s membranes which leads to increased intracellular water retention. Multi-frequency BIA can be considered to be an accurate and sensitive method for assessment of human body composition.
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Evaluating the accuracy of continuous glucose monitoring by the patient through continuous glucose error grid analysis
Honsová, Š. ; Navrátil, Tomáš
The aim of the study is to compare the difference between the accuracy declared by the producer of continuous glucose determination using the MiniMed Paradigm REAL-Time system with the results achieved by patients in real life. The glucose sensor evaluates the catalytic transformation of glucose (enzyme glucose dehydrogenase) to hydrogen peroxide, the concentration of which is electrochemically evaluated. The accuracy of measurements was determined by Clarke Error Grid Analysis. It can be concluded that in normal glyceamia (4.4 to 10.0 mmol/l) the measurements realized by the parients are more accurate that it is supposed by the producer, opposite to the cases of hypoglycaemia or hyperglycaemia.
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Transport of divalent cations across the gel supported phospholipid membranes
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
This contribution deals with elucidation of principles of transporting processes of heavy metals (mainly lead, cadmium) across the biological membranes. The real membranes were for purposes of described experiments, replaced by model membranes, which were composed of phospholipid bilayers. Two different phorpholipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine and the mixture of phospholipids obtained from soybeans (under commercial name Asolectin)) were used as the building elements for the formation of these membranes on the surface of the constructed gel electrode. The registered transporting processes have been characterized using voltammetry, and electrochemical impendance spectrometry (EIS). The impact of some parameters on these systems and processes was investigated.
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Changes in chemical composition of surface water at the model catchment Lesni potok during the spring snowmelt 2009
Navrátil, Tomáš ; Dobešová, Irena ; Rohovec, Jan ; Buchtová, Jana
Changes of surface water chemistry during the spring snowmelt were evaluated at the forested experimental catchment Lesni Potok found in National Reservation Area Voděradské bučiny. The pH value of surface waters decreased and together with high discharge it launched changes of solutes concentrations. As a good indicator of groundwater in the discharge were evaluated concentrations of Si and isotopic signature of 18O-H2O. The concentration of the main anion SO42- in waters of Lesni potok oscillated during the spring snowmelt in dependence of ratio between melting snow, soil solution, precipitation and groundwater. During the period of increased penetration of surface soil horizons with the water from melting snow causing the increase of DOC concentrations. Concentrations of DOC determined the export of total Fe. Concentrations of Al with DOC did not correlate because the driving factor on concentrations of Al at Lesni Potok is the surface water pH. Concentrations of NO3- were rapidly decreasing during the snowmelt and at the end of this episodic event NO3- concentrations were trivial due to the rapid flushing of soil horizons.
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