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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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Transport of cadmium ions across model supported phospholipid membranes
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír ; Štulík, Karel
These results report on experiments focussed on the formation of supported model phospholipid membranes, formed from phosphatidyl choline in the micrometric pores of hydrophilic polycarbonate supports, their chatacterization using voltammetry and electrochemical impendance spectrometry (EIS). Attention was paid transport of heavy metal ions (ions of cadmium, etc.) across these membranes in the presence or absence of ionophores (valinomysing and calciomycin) or in the presence of oxalic acid. The impact of some parameters on these systems and processes was investigated.
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Suplementace kreatinu u sportovce s hyperhomocysteinemií
Kohlíková, E. ; Petr, M. ; Navrátil, Tomáš ; Přistoupilová, K. ; Přistoupil, T. I. ; Pelclová, D. ; Žák, J. ; Heyrovský, Michael
One month's administration of creatine (CR) in the dose of 5 g/day to 11 young active sportsmen affected their daily amount of CR and creatinine excreted into urine. The probands were divided into 4 groups, according to the amount of CR found in urine, and of folates and of vitamin B12 determined in blood. The ganges of folates and vitamin B12 were mutually reciprocal. Each group utilized CR as donor of one- and two-carbon (1C and 2C) units by means of homocysteine (HoCySH), folates, and vitamin B12, in different metabolic pathways. In 10 men the CR administration was accompanied by an increase of HoCySH level in blood, while for the last man, with accidentally discovered hyperhomocysteinemia, after the month's CR administration the HoCySH level dropped by 50 %.
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Studium transportu iontů přes modelové fosfolipidové membrány
Navrátil, Tomáš ; Šestáková, Ivana ; Mareček, Vladimír
Synthetically prepared model phospholipid bilayers (PLBs) in the form of black membranes, vesicles or supported membranes, with incorporated ionophores or real ion channels (i.e., artificially synthesized or gained from real living cells, e.g. protoplasts) are promising for study and simulations of transporting processes across the real cell membranes and the membranes surrounding sub-cellular structures. The electrochemical methods were found to be very suitable and sensitive enough for characterization of such processes.
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Přenos kadmia přes biologické membrány
Šestáková, Ivana ; Navrátil, Tomáš
From complexing ligands, low molecular weight organic acids are important as plant exudates in soil solution, whereas sulfur containing - ligands phytochelatins - sequester Cd2+ inside the cell vacuole. Voltammetrically determined fytochelatins concentration could be correlated with total Cd concentration found in different parts of plant.
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