During the last decade or two the interest towards small molecules capable of self-assembly leading to gelation has increased intensively. The investigation of these supramolecular gels aims not only at understanding the fundamental processes underlying gel formation but also at development of new materials with a myriad of applications. Steroids are widely-spread natural products with a large and rigid steroidal nucleus combined with derivatizable functional groups leading to an adjustable polarity profile, which makes them attractive building blocks when designing novel low molecular weight gelators. Due to their unique properties, steroid-based supramolecular gels may find use in applications ranging from materials science and nanoelectronics to their application as reaction media or as sensing and responsive materials. Moreover, biomaterials based on steroidal gels may find use in biomedicine, drug delivery, regenerative medicine, and tissue engineering. This article summarizes the most recent advances in the field of steroidal supramolecular gels in terms of steroid-derived hydroand organogels, metallogels, two-component gels, and stimuli-responsive gels. Furthermore, the potential applications of the systems are discussed.

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Věžník A., Král M., Svobodová H., 2013. Agriculture of the Czech Republic in the 21st century: From productivism to post-productivism. Quaestiones Geographicae 32(4), Bogucki Wydawnictwo Naukowe, Poznań, pp. 7-14, 8 figs. DOI 10.2478/quageo-2013-0029, ISSN 0137-477X.abstract: During last two decades Czech agriculture has gone through significant changes: the transition of agriculture in the 1990s and the entrance of the Czech Republic into the EU and its commitment to the Common Agricultural Policy (CAP). Both of these changes contributed to the structural and regional differentiation of Czech agriculture and exposed it to competition with the whole of Europe. Furthermore, CAP exposed Czech agriculture to uneven conditions for farmers within the EU. The most significant results of these changes have been a decrease in the agricultural sector output, a reduction in farm animals bred, and shrinkage of arable land. On the other hand, many non-productive and non-agricultural activities in the rural areas are subsidised, which offers farmers new possibilities of development. The aim of this paper is to analyse the structural and spatial change in Czech agriculture between 2000 and 2010 on the basis of Agrocenzus data supplemented by opinions of farmers gained in a series of interviews.

Sulfur mustard (SM) is a chemical warfare agent with cytotoxic effect and a tight link to oxidative stress (OS). Depletion of antioxidants is considered as a cause of detrimental consequence and belongs to the important steps leading to cell death. The oxidative injury appearing after SM exposure is not well understood. Nevertheless, identification of the pathological processes would be a good opportunity to establish an efficient therapy. Here, we focused our effort on an estimation of reactive oxygen species homeostasis and apoptotic processes in Wistar rats exposed to 0-160 mg/kg of SM. We assayed antioxidant activity, thiobarbituric acid reactive substances, reduced glutathione/oxidized glutathione, metallothionein, glutathione reductase, glutathione peroxidase, glutathione S-transferase, caspase 3, and glucose in the livers, kidneys, and muscles of the animals. Significant OS, depletion of low-molecular-mass antioxidants, increase in caspase activity, and some other processes related to SM action were determined. Moreover, we infer a principal role of OS in the tested organs.

The development of Norway spruce (Picea abies (L.) Karst.) somatic embryos on a maturation medium was accompanied by changes in nonstructural carbohydrate status. During embryo maturation, the content of total soluble sugars in the embryonal suspensor mass decreased and the partitioning between sucrose and hexoses changed considerably in favor of sucrose. Developing somatic embryos were mainly responsible for these changes. Osmotic stress caused by the presence of 3.75% polyethylene glycol (PEG) in the maturation medium (decrease in osmotic potential by 52.5 kPa) resulted in dramatic changes in the content of endogenous saccharides. There was a lower total carbohydrate content in the embryonal suspensor mass grown on the medium containing PEG in comparison with the untreated control. Isolated embryos from later stages of embryo development contained mainly sucrose with a small amount (20%) of fructose and nearly no glucose. A further increase in PEG concentration in the medium (7.5%; decrease in osmotic potential by 112.5 kPa compared to the maturation medium) led to a large increase in the total endogenous sugar content. This increase in sugars was a result of the enhanced content of sucrose, fructose, and glucose. The increased glucose content was in contrast to embryos grown on the medium with lower or no PEG content.