At frog neuromuscular junction, noradrenaline (NA) shortens the release period for evoked quantal release acting on a b 1 receptor. To test the hypothesis that this action of NA is mediated by cAMP, we measured the latencies of focally recorded uni-quantal endplate currents (EPCs) after application of dibutyryl-cAMP (db-cAMP) and adenylyl cyclase activator, forskolin. The interval between the time when responses with minimal delay appeared and the point at which 90 % of all latencies had occurred (P90 parameter) was shortened in the presence of both 1x10-6 mol/l db-cAMP and 1x10-6 mol/l forskolin by about 30 %. The cAMP-induced shortening is equal to that found after application of NA and effects of both drugs are not additive., E. Bukcharaeva, D. Samigullin, E. E. Nikolsky, F. Vyskočil., and Obsahuje bibliografii
Within the framework of our studies on hypertension in various rat strains, we have examined the effect of cyclosporin A (CsA) on intracellular calcium signaling under conditions of oxidative stress. For these preliminary experiments, we have chosen isolated hepatocytes of normotensive rats as a model system for the study of the role of intracellular calcium. We used tert-butyl hydroperoxide (t-BHP, 1 mmol.l-1) as an prooxidant agent. When compared to the controls, we found increased levels of cytosolic free calcium concentration (Ca2+i) during 120 min incubation. The preincubation of hepatocytes with CsA in the concentration of 0.5 m mol.l-1 did not change the physiological level of cytosolic calcium. However, a dual action of CsA on elevated Ca2+i was observed during oxidative injury of hepatocytes: while in the first period of incubation CsA increased Ca2+i, CsA reduced the effect of t-BHP on Ca2+i during the next period of incubation. This indicates the ability of CsA to modify oxidative stress, but further studies are necessary to explain these findings., E. Kmoníčková, L. Kameníková, S. Hynie, H. Farghali., and Obsahuje bibliografii
The Institute of the Rock Structure and Mechanics AS CR operates the GEONAS network that now consists of 17 perm anent GPS observatories. The outliers and in consistencies occur within the time series observed in the winter season 200 5/2006 for the position of the GNSS antennas of the observatories SNEC and BISK located high in the m ountains, at th e Sněžka Mt. (1602 m, the Giant Mts.) and the Biskupská kupa Mt. (890 m, the Jeseníky Mts.) respectively. Therefore web cameras and meteorological sensors were in stalled at GEONAS observatories located in the mountain regions. The snow coverage and other meteorological influences affecti ng the antennas monitoring GPS signals at these observatories were estimated. The individual photos were analyzed and compared to variations in the time series to obtain the time series for winter seasons reducing the snow coverage effects., Milada Grácová, František Mantlík, Vladimír Schenk and Zdeňka Schenková., and Obsahuje bibliografické odkazy
Mitochondrial dysfunction and oxidative stress participate in the development of diabetic complications, however, the mechanisms of their origin are not entirely clear. Coenzyme Q has an important function in mitochondrial bioenergetics and is also a powerful antioxidant. Coenzyme Q (CoQ) regenerates alpha-tocopherol to its active form and prevents atherogenesis by protecting low-density lipoproteins against oxidation. The aim of this study was to ascertain whether the experimentally induced diabetes mellitus is associated with changes in the content of endogenous antioxidants (alpha-tocopherol, coenzymes Q9 and Q10) and in the intensity of lipoperoxidation. These biochemical parameters were investigated in the blood and in the isolated heart and liver mitochondria. Diabetes was induced in male Wistar rats by a single intravenous injection of streptozotocin (45 mg.kg-1), insulin was administered once a day for 8 weeks (6 U.kg-1). The concentrations of glucose, cholesterol, alpha-tocopherol and CoQ homologues in the blood of the diabetic rats were increased. The CoQ9/cholesterol ratio was reduced. In heart and liver mitochondria of the diabetic rats we found an increased concentration of alpha-tocopherol, however, the concentrations of CoQ9 and CoQ10 were decreased. The formation of malondialdehyde was enhanced in the plasma and heart mitochondria. The results have demonstrated that experimental diabetes is associated with increased lipoperoxidation, in spite of the increased blood concentrations of antioxidants alpha-tocopherol and CoQ. These changes may be associated with disturbances of lipid metabolism in diabetic rats. An important finding is that heart and liver mitochondria from the diabetic rats contain less CoQ9 and CoQ10 in comparison with the controls. We suppose that the deficit of coenzyme Q can participate in disturbances of mitochondrial energy metabolism of diabetic animals., J. Kucharská, Z. Braunová, O. Uličná, L. Zlatoš, A. Gvozdjáková., and Obsahuje bibliografii
Stáří a stárnutí jedinců jsou bezpochyby fenomény, které zaujímaly významné místo ve společnosti již v dobách dávno minulých. Během 20. století však nabrala otázka stárnutí nového rozměru, neboť začala nově přesahovat z úrovně individuální na úroveň celospolečenskou. V důsledku zlepšování některých společenských podmínek (např. lékařské péče, životního stylu, hygieny, životní úrovně atd.), jež bylo nastartováno již zhruba na počátku 19. století, dochází k odsouvání úmrtí do vyšších věků, a lidé tak žijí déle. V moderních společnostech je tento jev obvykle doprovázen poklesem porodnosti a plodnosti. Kombinace těchto dvou faktorů pak ve svém konečném důsledku způsobuje proces, který nazýváme demografickým stárnutím. Obecně je tedy třeba rozlišovat dva pohledy na problematiku stárnutí. První pohled se zaměřuje na tzv. stárnutí individuální, druhý přístup se zabývá demografickým stárnutím lidských populací, ovšem je zřejmé, že obě dvě hlediska jsou mezi sebou navzájem provázaná. Podobně tomu bude i v následujícímpříspěvku, jenž se bude zabývat nejen přehledem problematiky demografického stárnutí, ale dotkne se také otázek o dlouhověkosti a kvalitě života, které se dostávají do popředí v souvislosti s tematikou stárnutí jednotlivců., Old age and aging of individuals are phenomenons that took important place in society as early as former times. During twentieth century the question of aging got new meaning, because it newly started to overreach from individual level to all-society. As a result of improvement of some social conditions (f.e. medical care, lifestyle, hygiene, living standard etc.), that was already initiated approximately at the beginning of the nineteenth century, dying started to be moved to higher age and people live longer. In modern societies this event usually goes with decline of natality and fertility. In final effect combination of these two factors causes the process that is known as demographic aging. In general we have to distinction between two views of problems of aging. The first view is focused on individual aging, the second one on demographic aging of human population. But it is clear that both of these views relate to each other. Similarly this article offers the roundup of problems of demographic aging, but also gives a touch of questions about longevity and quality of life, that gain ground in connection with theme of individual aging., Michaela Dimitrová., and Seznam literatury
Dírkonošci (Foraminifera), mořští prvoci s vápenatou schránkou, obývají naši planetu více než půl miliardy let. Zkoumáním způsobu života těch současných se mnohé dozvíme o jejich pravěkých předcích i o dávných mořích, ve kterých žili., Foraminifera - a rich group of mainly marine microorganisms - are widely used for paleoecological reconstructions. Their occurrence provides important data about past ecological conditions of the sites. We reconstructed former conditions in Židlochovice research site (southern Moravia) by comparing fossil communities with the recent ones present on the island of Rab (Adriatic Sea)., and Anna Poštulková.
Předkládaný článek přináší stručný průřez problematiky studia taxonomie štírů rodu Euscorpius. Evropským štírům byla věnována pozornost již od poloviny 18. století. Po bezmála 250 letech zkoumání se tento rod stále nedočkal vyřešení otázky své komplikované taxonomie. Zdá se ovšem, že současné studie kombinující morfologické, genetické a cytogenetické znaky mohou být klíčem pro odhalení skutečné druhové diverzity., This article briefly summarizes the last two and a half centuries of taxonomic research into the European genus of scorpions commonly known as small wood scorpions (Euscorpius). Despite the fact that taxonomists have been focusing on this genus since the mid-18th century, their taxonomy is not yet sufficiently resolved. However, present studies seem to be on the right track, and looking into a combination of morphological, genetic and cytogenetic features may hold the key to revealing the true diversity of the species., and Jana Plíšková.
Pokles kyselé atmosférické depozice od 90. let minulého století a rovněž postupné oteplování klimatu bylo prokazatelně doloženo i pro horské ekosystémy v nejvyšších slovenských pohořích. Výzkumy epigeické aktivity mnohonožek (Diplopoda) v letech 1992-1993, 1997-1998, 2007-2008 a pokračující sledování v současnosti svědčí o rozmanitosti společenstev těchto půdních bezobratlých včetně přítomnosti řady karpatských endemitů v závislosti na odlišném geologickém podloží (žula a vápenec) a typu vegetace. Pozorovaný ústup chladnomilných endemitů i nárůst podílu eurytopních adaptabilních druhů lze dávat do souvislosti s probíhajícími změnami v chemismu půd i změnami klimatu., The decline of acid deposition since the 1990s, together with subsequent climate warming, was confirmed also for mountain ecosystems in the highest Slovak mountains. The study of epigeic activity of millipedes (Diplopoda) in the periods 1992-93, 1997-98 and 2007-08, and continuing recent research refer to the high diversity of their communities including the presence of Carpathian endemic species on different geological bedrocks (granite and limestone) as well as different vegetation covers. The observed decline of cold tolerant endemics and the increasing portion of eurytopic species may be connected with changes in soil chemistry as well as with climate changes., and Karel Tajovský.
Přesné měření je nezbytné pro úspěšné stavební práce i kontrolu stability objektů, to věděli i naši předkové. Dnes existují velmi citlivé přístroje, které odhalí sebemenší pohyby svahů, mostů, hrází či vysilačů a pomohou tak předejít katastrofě. S detailními postupy, jak moderní měřici technologii využít a analyzovat data, přišel tým výzkumníků z Ústavu teorie informace a automatizace AV ČR ve spolupráci s firmou Geodézie Ledeč nad Sázavou. and Leona Matušková, Stanislava Kyselová.