Multidrug resistance of cancer cells is often accompanied by the (over)expression of integral plasma membrane P-glycoprotein, an ATP-dependent transport pump for diverse unrelated compounds. The glutathione detoxification system represents another mechanism that may be involved in multidrug resistance. In the multidrug-resistant L1210/VCR cell line obtained by long-term adaptation of parental L1210 cells to vincristine, an increased expression of P-glycoprotein has previously been established. In this paper, we investigated if the glutathione detoxification system is also involved in the multidrug resistance of these cells. L1210/VCR cells with resistance induced by adaptation to vincristine were also found to be cross-resistant to vinblastine, actinomycin D, mitomycin C, doxorubicin and cyclophosphamide. The resistance of the above cells to vincristine and doxorubicin was accompanied by a depression of drug accumulation (which has not yet been established for other drug). L1210/VCR cells are able to survive better than sensitive cells under conditions when glutathione was depleted by L-buthionine sulfoximine. Nevertheless, L-buthionine sulfoximine did not influence the resistance of L1210/VCR cells to vincristine. Moreover, the presence of sublethal concentrations of cytostatics neither changed the IC50 value of resistant cells to L-buthionine sulfoximine nor the cytoplasmic activity of glutathione S-transferase, the crucial enzyme of glutathione detoxification system. All the above findings indicate that the glutathione detoxification system is not involved in the mechanisms that ensure the multidrug resistance phenotype of L1210/VCR cells., V. Boháčová, J. Kvačkajová, M. Barančík, Z. Drobná, A. Breier., and Obsahuje bibliografii
The actívities of glycine oxidase (GO) and serine dehydratase (SD) were revealed in green leaves of wheat and maize. The enzymes were extracted by ammonium sulfáte fractionation. GO localized in chloroplast and cytosolic fraction was most active at pH 8.0. Its activity was 1.5-2.0 times higher in wheat than in maize and it declined with leaf aging. The enzyme converts glycine into glycollate and ammonium ion being flavine dependent and generating H2O2. We propose that it is an L-amino-acid oxidase (EC 1.4.3.2) with a higher specificity to glycine. The activity of SD (EC 4.2.1.13) localized in chloroplasts was maximum at pH 7.0-7.2, it was also higher in wheat than in maize. Pyruvate was determined as a product of enzymatic conversion of L-serine. SD and GO actívities were not revealed in etíolated leaves.
The retina is characterized by glycolysis under aerobic conditions, mediated by lactate dehydrogenase isoenzyme-5 (LDH-5) as well as by the soluble isoenzyme of malate dehydrogenase. Bovine retina LDH and MDH isoenzymes and their activities were studied after polyamine treatment. Our results showed that LDH-5 isoenzyme presented the highest activity in untreated as well as in putrescine-treated retina. Decreased activity was present when the retina was treated with spermidine or spermine. It was demonstrated that retinic LDH-5 had a high affinity for lactate which enabled the isoenzyme to be more effective than the other LDH isoenzymes in the conversion of NADH to NAD. Therefore, the putrescine enhancing LDH-5 activity appeared to be capable of stimulating NAD-mediated rhodopsin regeneration. Putrescine induced a marked increase of both MDH isoenzymes - soluble (s-MDH) and mitochondrial (m-MDH), while spermine and spermidine mostly affected the soluble form of the enzyme. Putrescine induced a three-fold increase in s-MDH and m-MDH activities, while spermine and spermidine induced a four to five-fold increase in s-MDH. These results document the differential effects of polyamine treatment on LDH and MDH isoenzyme activities., I. Venza, A. Valenti, P. Ruggeri, L. Denaro, D. Teti., and Obsahuje bibliografii
A large body of evidence has implicated reactive carbonyl compounds as glycotoxic mediators of carbonyl stress. This review is focused on the pathophysiological effects of α-oxoaldehydes in diabetes and related complications, summarizing the state-of-the-art on the endogenously produced carbonyls methylglyoxal, glyoxal and 3-deoxyglucosone, formed as glycolytic intermediates during metabolic conversion of glucose, via Maillard reaction by degradation of glycated proteins, and during lipid peroxidation process. Their role in the advanced glycation process and detrimental effects on vascular tissue are discussed., Z. Turk., and Obsahuje bibliografii a bibliografické odkazy
The OECD “Programm for International Student Assessment (PISA)” has shown that Finland is very successful in education for mathematics and science. Data for Finland, USA, Germany and Czech Republic are given. The analysis makes it clear that the decisive factor is teaching on the background of Mach's sensualism with empiric knowledge theory and a Darwinian genetic approach to scientific knowledge., Projekt OECD "Program pro mezinárodní hodnocení žáků (PISA)" ukázal, že v matematicko-přírodovědném vzdělávání dosahuje Finsko mimořádně dobrých výsledků. Údaje jsou uvedeny pro Finsko, USA, Německo a Česko. Analýza nasvědčuje tomu, že rozhodujícím faktorem je výuka založená na machovských senzualistických empirických poznatcích a uplatňování darwinovské geneze poznávání vědeckých zákonitostí., Hayo Siemsen ; z němčiny přeložil Martin Černohorský., and Obsahuje seznam literatury a v příloze dva výňatky z Machovy učebnice
a1_The aim of this paper is to present the strategy of determination of the reference solution for the ASG-EUPOS (Active Geodetic Network - European Position Determination System) coordinate monitoring system. ASG-EUPOS is a network of permanent GNSS (Global Navigation Satellite System) stations controlled by the Polish Head Office of Geodesy and Cartography (HOGC), which main role is to realize the ETRS89 (European Terrestrial Reference System) in the territory of Poland. The Centre of Applied Geomatics (CAG) of the Military University of Technology (MUT) performs a control processing of the network and it is the leader of the ASG+ (the supporting modules for ASG-EUPOS system real-time services) project within which the coordinate monitoring system was developed. The coordinate monitoring is aimed to assess the actual performance of the GNSS stations and the reliability of the system and its services. The Polish realization of the ETRS89 is also controlled, where the deviation of the actual coordinates from the reference values are monitored. Furthermore, the monitoring enables the analysis of factors that degrade the individual GNSS stations and assess the solution stability which has impact on the quality of the determined geodynamic parameters. The reference solutions (coordinates and their changes over time) were determined according to the recommendations of the IAG sub-commission for the European Reference Frame concerning densification of EUREF. The paper presents the determination of the reference cumulative solution and the results of the processing of a few years long series of GNSS observations. The analysis are performed by the Bernese 5.0 and CATREF software. The results consists of daily and subdaily ASG-EUPOS reference solutions. They are also considered as input data for geodynamic studies to determine the horizontal and vertical velocity fields., a2_Estimation of the individual station velocities is of crucial importance for the ETRF (European Terrestrial Reference Frame) reference frame maintenance to assess the compatibility of the current station position with its catalogue (reference) value and apply coordinate correction if necessary., Karolina Szafranek, Janusz Bogusz and Mariusz Figurski., and Obsahuje bibliografii
The Second Argentine - Czech Biennale Workshop E-Golem took place in Buenos Aires on September 24-26, 2007. It was organized by the Czech Ministry of Foreign Affairs and the Secretariat for Science, Technology and Productive Innovation of the Argentine Republic, with suppport from the Czech Embassy in Argentine and the Argentine Embassy in the Czech Republic. Its general subject was Society of information and Communication - Emerging technologies and their applications in society and the arts. The aim of this event was to discuss this issue in detail such topics as, artificial intelligence, image processing, web-technologies, nano-technologies for life sciences, eco-technologies and so forth. More information on this project can be found in an interview in this issue with the Ambassador of the Argentine Republic in the Czech Republic, Ambassador Juan Eduardo Fleming. and Marina Hužvárová.