Tokamak - pinč - tokamak. Jak vysvětlit překvapivou odbočku z tokamakové dálnice na pinčovou okresku výzkumu řízené termojaderné fúze v moskevském ústavu LIPAN v letech 1952-1953? Konfrontací dvou události se podařilo do "záhady" vnést alespoň trochu světla. Těmi událostmi bylo setkání fyziků v roce 1947 v Harwellu a návštěva Olega Alexandroviče Lavrentěva ve fúzní skupině oddělení výzkumu plazmatu ústavu LIPAN v roce 1991. O. A. Lavrentěv v laboratoři spatřil Wirbelrohr!, Max Seenbeck named his modification of the circular accelerator betatron as the Wirbelrohr in the year 1943. The Wirbelrohr co-initiated research on controlled thermonuclear fusion in the UKA in the late forties. It is likely that the Wirbelrohr device slightly delayed research on the predecessor to the magnetic thermonuclear reactor, tokamak, in the Soviet Union., Milan Řípa., and Obsahuje seznam literatury
Adjuvantná rádioterapia prispieva k lepším výsledkom u pacientov s karcinómom prsníka po prsník zachovávajúcej operácii. Ožarovanie celého prsníka je spojené s poškodením srdca a pľúc, zvýšením kardiovaskulárných ochorení a mortality, a vývojom karcinómu pľúc, teda s rizikami, ktoré sa môžu objaviť 15–20 rokov po liečbe. Ožarovanie prsníka v pronačnej polohe pacientky je jednou z možností ako redukovať radiačne podmienenú toxicitu u pacientiek s veľkými prsníkmi podstupujúcimi adjuvantnú liečbu. V kazuistikách poukážeme na rozdiely v objeme srdca a pľúc pri oboch polohách, porovnáme dozimetrické parametre pri ožarovaní prsníka v oboch pozíciách a poukážeme na rozdiely pri ich plánovaní. Tieto techniky nie je možné kombinovať s ožiarením lymfatických uzlín, ale môžu byť použité pri liečbe obojstranných nádorov., Adjuvant radiotherapy contributes to better outcomes in patients with breast cancer after breast conserving surgery. Whole breast irradiation is associated with damage to the heart and lungs, increased cardiovascular mortality, and the development of lung cancer, that is, with the risks that may occur 15–20 years after treatment. Breast irradiation in the prone position, is one of the way to reduce radiation toxicity in patients conditioned with large breasts undergoing adjuvant therapy. In case reports point out the differences in the volume of the heart and lungs at both locations, we compare the dosimetric parameters in breast irradiation in both positions and point out the differences in their planning. These techniques can not be combined with irradiation of the lymph nodes, but they can be used in the treatment of bilateral tumors., Andrea Masaryková, David Lederleitner, and Literatura
The administration of creatine (5 g/day for one month) to 11 young active sportsmen affected their urinary excretion of creatine, creatinine, and thiodiglycolic acid (TDGA) as well as blood levels of homocysteine, vitamin B12 and folates. The probands were divided into four groups, according to the amount of creatine found in urine, and of folates and vitamin B12 determined in blood. The changes 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 creatine administration was accompanied by an increase of HoCySH level in blood, while in the last man, with accidentally discovered hyperhomocysteinemia, the HoCySH level dropped by 50 %. Differences between initial and terminal TDGA levels indicate that creatine affects equilibria of redox processes. Creatinine excretion into urine changed in the dependence on the extent of metabolic disturbances., T. Navrátil ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Inhalational anesthetic-induced preconditioning (APC) has been shown to reduce infarct size and attenuate contractile dysfunction caused by myocardial ischemia. Only a few studies have reported the effects of APC on arrhythmias during myocardial ischemia-reperfusion injury, focusing exclusively on reperfusion. Accordingly, the ai m of the present study was to examine the influence of APC on ventricular arrhythmias evoked by regional no-flow ischemia. APC was induced in adult male Wistar rats by 12-min exposures to two different concentrations (0.5 and 1.0 MAC) of isoflurane followed by 30-min wash-out periods. Ventricular arrhythmias were assessed in the isolated perfused hearts during a 45- min regional ischemia and a subsequent 15-min reperfusion. Myocardial infarct size was determined after an additional 45 min of reperfusion. The incidence, severity and duration of ventricular arrhythmias during ischemia were markedly reduced by APC. The higher concentration of isoflurane had a larger effect on the incidence of ventricular fibrillation than the lower concentration. The incidence of ventricular tachycardia and reversible ventricular fibrillation during reperfusion was also significantly reduced by APC; the same was true for myocardial infarct size. In conclusion, we have shown that preconditioning with isoflurane confers profound protection against myocardial is chemia- and reperfusion-induced arrhythmias and lethal myocardial injury., H. Říha ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Self-organization in a polymer system appears when a balance is achieved between long-range repulsive and short-range attractive forces between the chemically different building blocks. Block copolymers forming supramolecular assemblies in aqueous media represent materials which are extremely useful for the construction of drug delivery systems especially for cancer applications. Such formulations suppress unwanted physicochemical properties of the encapsulated drugs, modify biodistribution of the drugs towards targeted delivery into tissue of interest and allow triggered release of the active cargo. In this review, we focus on general principles of polymer selforganization in solution, phase separation in polymer systems (driven by external stimuli, especially by changes in temperature, pH, solvent change and light) and on effects of copolymer architecture on the self-assembly process., M. Hrubý, S. K. Filippov, P. Štěpánek., and Obsahuje bibliografii
One hundred years ago Heike Kamerlingh Onnes arrived to one of the most important breakthroughs of 20th century physics - he discovered superconductivity. His finding as in many other cases in the history of science had been a result of use of a very new experimental technique. He used the cryogenic equipment in his Leiden's laboratory with the liquid helium cryocooler and measured electrical properties of metals near the absolute zero temperature. When cooled down to extremely low temperatures, near 4 Kelvin, very pure mercury suddenly lost its electrical resistance completely. Many major physicists of 20th century, experimentalists as well as theorists, devoted their life efforts to exploration of the mysterious properties of superconductors. Superconductivity has been shown to be one of the rare cases where quantum physics is observed on a macroscopic scale. Many chemical elements and thousands of compounds have been found to be superconducting. Fifty years after the discovery important practical applications such as strong magnets for laboratories and magnetic-resonance-imaging in hospitals came to the market. But more than seventy five years the superconducting materials had been functioning only at extreme cold, below 23 K (-250°C). In 1986 the "hightemperature superconductor's" era started with materials superconducting at -100°C. This paper surveys the history and the latest research into one of today's most fascinating physics and promising technologies., Peter Samuely., and Obsahuje bibliografii
The effect of suramin, an inhibitor of G protein regulated signalling, was studied on the membrane currents induced by noxious heat and by capsaicin in cultured dorsal root ganglia neurones isolated from neonatal rats. Whole-cell responses induced by a heat ramp (24-52 °C) were little affected by suramin. The noxious heat-activated currents were synergistically facilitated in the presence of 0.3 µM capsaicin 13.2-fold and 6.3-fold at 40 °C and 50 °C, respectively. In 65% of neurones, the capsaicin-induced facilitation was inhibited by 10 µM suramin to 35±6 % and 53±6 % of control at 40 °C and 50 °C (S.E.M., n=15). Suramin 30 µM caused a significant increase in the membrane current produced by a nearly maximal dose (1 µM) of capsaicin over the whole recorded temperature range (2.4-fold at 25 °C and 1.2-fold at 48 °C). The results demonstrate that suramin differentially affects the interaction between capsaicin and noxious heat in DRG neurones and thus suggest that distinct transduction pathways may participate in vanilloid receptor activation mechanisms., V. Vlachová, A. Lyfenko, L. Vyklický, † R.K. Orkand., and Obsahuje bibliografii