Hypoxic exposure triggers a generation of reactive oxygen species that initiate free radical damage to the lung. Hydrogen peroxide is the product of alveolar macrophages detectable in the expired breath. We evaluated the significance of breath H2O2 concentration for the assessment of lung damage after hypoxic exposure and during posthypoxic period. Adult male rats were exposed to normobaric hypoxia (10 % O2) for 3 hours or 5 days. Immediately after the hypoxic exposure and then after 7 days or 14 days of air breathing, H2O2 was determined in the breath condensate and in isolated lung macrophages. Lipid peroxidation was measured in lung homogenates. Three-hour hypoxia did not cause immediate increase in the breath H2O2; 5-day hypoxia increased breath H2O2 level to 458 %. After 7 days of subsequent air breathing H2O2 was elevated in both groups exposed to hypoxia. Increased production of H2O2 by macrophages was observed after 5 days of hypoxia and during the 7 days of subsequent air breathing. Lipid peroxidation increased in the periods of enhanced H2O2 generation by macrophages. As the major increase (1040 %) in the breath H2O2 concentration found 7 days after 3 hours of hypoxia was not accompanied by lipid peroxidation, it can be concluded that the breath H2O2 is not a reliable indicator of lung oxidative damage., J. Wilhelm, M. Vaňková, H. Maxová, A. Šišková., and Obsahuje bibliografii
The two stage co-pyrolysis method for obtaining of hydrogen is described. In the course of the heating of the mixture of bituminous coal with polyisoprene and styrene-butadiene polymers (co-pyrolysis), a considerable amount of hydrogen and hydrocarbons is released in dependence on the process conditions. The experiments proved that the amount of hydrogen increased already with slightly increased heating rate (5 K min-1 ) in comparison with the amount obtained at a common heating rate (3 K min-1) and, further, with the addition of the second (cracking) stage for further thermal splitting of release d hydrocarbons into hydrogen (and carbon), preferably at a temperature of 1200 ºC., Pavel Straka and Vlastimil Kříž., and Obsahuje bibliografické odkazy
As a novel gasotrans mitter, h ydrogen sulfide (H 2 S) has vasodilating and antihypertensive effects in cardiovascular system. Thus, we hypothesized that H 2 S might have beneficial effects on thoracic endothelial function in two -kidney one -clip (2K1C) rats, a model of renovascular hypertension. Sodium hydrosulfide (NaHS , 56 μmol/kg /day ) was administrated intra - peritoneally from the third day after the 2K1C operation. Along with the development of hypertension, t he systolic blood pressure (SBP) was measured before the operation and each week thereafter. The oxidative stress wa s determined by measurement of malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity and protein expression of oxidative stress -related proteins (AT 1 R, NADPH oxidase subunits). Acetylcholine (ACh) -induced vasorelaxation and angiotensin I I (Ang II) -induced vasocontraction were performed on isolated thoracic aorta. The SBP w as significantly increased from the first week after operation , and was lowered by NaHS. NaHS supplementation ameliorated endothelial dysfunction. The protein expression of oxidative stress -related proteins were downregulated, while SOD activity upregulated. In conclusion, improvement of endothelial function is involved in the antihypertensive mechanism of H 2 S. The protective effect of H 2 S is attributable to suppression o f vascular oxidative stress that involves inhibition of Ang II -AT 1 R action, downregulation of oxidases, as well as upregulation of antioxidant enzyme., H. Xue, S. Zhou, L. Xiao, Q. Guo, S. Liu, Y. Wu., and Obsahuje bibliografii
by O. Nordgaard. The protist plankton and the diatoms in bottom samples / by E. Jørgensen., KČSN - signatura S-E 128, Poškozené desky., and Desky skenovány z jiné signatury. S-E 128
Předkládaný článek se soustředí na klíčové období výstavby vodních infrastruktur v Československu, kterým jsou bezpochyby padesátá léta minulého století. Tehdejší masivní výstavba víceúčelových vodních děl, zejména přehradních nádrží a elektráren, ale i vodovodů, probíhající v kontextu socialistické industrializace, položila základy stávajícího státního vodohospodářského systému. V jejím čele stála skupina vodohospodářských odborníků (takzvaných hydrokratů), která se formovala již od dvacátých let. Tito experti zastávali ideály modernistické vodohospodářské mise, směřující k racionalizaci a depolitizaci hospodaření s vodou a spatřující v plném ovládnutí povrchového odtoku základní předpoklad budoucí prosperity státu i obyvatelstva. Období stalinismu podle autora přineslo ideální podmínky k naplnění těchto vizí (zestátnění vodních staveb a zdrojů, centralizace správy i investiční činnosti, ideje přeměny přírody), zároveň byl ale tradiční hydrokratický projekt kompromitován produktivistickými imperativy, což nakonec vedlo k opuštění holistických idejí vyjádřených ve Státním vodohospodářském plánu na roky 1949 až 1953 a jednoznačné soustředění na akumulaci vody pro potřeby průmyslu a energetiky. Od roku 1956 pak v reakci na rostoucí znečištění životního prostředí vznikaly tlaky směřující k přehodnocení stávající vodohospodářské politiky, což v důsledku znamenalo také postupnou korozi idejí vodohospodářské mise., The article focuses on the unquestionably most important period of construction of hydraulic infrastructures in Czechoslovakia, i.e. the 1950s. The massive construction of multi-purpose hydraulic structures, in particular dams and power plants, but also water mains, which was at that time taking place in the context of socialist industrialization, laid the foudnations of the existing national water management system. It was led by a group of water management experts, so-called hydrocrats, which had been forming up since the 1920s. These experts were advocates of ideas of a modernistic water management mission aiming to rationalize and depoliticize water managementand seeing full control of surface runoff as an essential prerequisite of the future prosperity of the state and its population. According to the author, the era of Stalinism brought ideal conditions for the fulfillment of these visions (nationalization of hydraulic structures and water resources, centralization of administration and investment activities, nature transformation ideas); at the same time, however, the traditional hydrocratic project was compromised by imperatives of productivism, which fact ultimately led to the abandonment of holistic ideas formulated in the 1949-1953 National Water Management Plan and a definite concentration on accumulation of water to satisfy needs of the industry and power engineering. Since 1956, there were pressures reacting to increasing environmental pollution levels and calling for a reassessment of the existing water management policy; as a consequence, the ideas of the water management mission were gradually corroding as well., Jiří Janáč., and Obsahuje bibliografii a bibliografické odkazy