Although atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice, precise mechanisms that lead to the onset and persistence of AF have not completely been elucidated. Over the last decade, outstanding progress has been made in understanding the complex pathophysiology of AF. The key role of ectopic foci in pulmonary veins as a trigger of AF has been recognized. Furthermore, structural remodeling was identified as the main mechanism for AF persistence, confirming predominant role of atrial fibrosis. Systemic inflammatory state, oxidative stress injury, autonomic balance and neurohormonal activation were discerned as important modifiers that affect AF susceptibility. This new understanding of AF pathophysiology has led to the emergence of novel therapies. Ablative interventions, renin-angiotensin system blockade, modulation of oxidative stress and targeting tissue fibrosis represent new approaches in tackling AF. This review aims to provide a brief summary of novel insights into AF mechanisms and consequent therapeutic strategies., B. Aldhoon ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Bone metabolism is regulated by interaction between two skeletal cells – osteoclasts and osteoblasts. Function of these cells is controlled by a number of humoral factors, including neurohormones, which ensure equilibrium between bone resorption and bone formation. Influence of neurohormones on bone metabolism is often bimodal and depends on the tissue, in which the hormone is expressed. While hypothalamic beta-1 and beta-2-adrenergic systems stimulate bone formation, beta-2 receptors in bone tissue activate osteoclatogenesis and increases bone resorption. Chronic stimulation of peripheral beta-2 receptors is known to quicken bone loss and alter the mechanical quality of the skeleton. This is supported by the observation of a low incidence of hip fractures in patients treated with betablockers. A bimodal osteo-tropic effect has also been observed with serotonin. While serotonin synthetized in brain has osteo-anabolic effects, serotonin released from the duodenum inhibits osteoblast activity and decreases bone formation. On the other hand, both cannabinoid systems (CB1 receptors in the brain and CB2 in bone tissue) are unambiguously osteoprotective, especially with regard to the aging skeleton. Positive (protective) effects on bone have also been shown by some hypophyseal hormones, such as thyrotropin (which inhibits bone resorption) and adrenocorticotropic hormone and oxytocin, both of which stimulate bone formation. Low oxytocin levels have been shown to potentiate bone loss induced by hypoestrinism in postmenopausal women, as well as in girls with mental anorexia. In addition to reviewing neurohormones with anabolic effects, this article also reviews neurohormones with unambiguously catabolic effects on the skeleton, such as neuropeptide Y and neuromedin U. An important aim of research in this field is the synthesis of new molecules that can stimulate osteo-anabolic or inhibiting osteo-catabolic processes., I. Žofková, P. Matucha., and Obsahuje bibliografii
A new spined loach species Cobitis jadovaensis is described from the Jadova River in Croatia. This species differs from its congeners in the Croatian Adriatic basin with a unique set of characters: a very short dorsal fin base; short anal fin base; narrow head; a single lamina circularis; a single small prominent dark inclined spot on the upper part of the caudal base; all four Gambetta zones well developed and reaching beyond the dorsal base; zones Z1 and Z3 with many irregular spots; zone Z1 narrower than Z2; zone Z2 as wide as Z3; zone Z2 with spots larger than a pupil size fuses with Z3 on caudal peduncle; zone Z4 wider than Z2 and Z3, with 11 – 14 roundish to oval blotches.
A modern seismological network with telemetric data transfer has been constructed in southern Bohemia. The network is made up of 5 stations equipped with Reftek DAS (Data Acquistion System) 130-01 Broadband Seismic Recorders and GeoSIG VE-53 triaxial velocity sensors with a natural frequency of 1 Hz. The network works at a sample rate of 250 Hz. The main purpose of this network is to monitor local seismicity in southern Bohemia with a special focus on seismic activity in the vicinity of the Temelin NPP. The sensitivity in the central part of the network is at least 0.0 ML. In addition to monitoring local tectonic movements it also monitors the effects of Alpine earthquakes in the area of southern Bohemia. For this reason one of the sites on the network is equipped with a GeoSIG AC-63 triaxial force balanced accelerometer., Vladimír Nehybka, Romana Hanžlová, Jan Otruba, Jan Švancara and Radim Vlach., and Obsahuje bibliografické odkazy
This contribution is focused on the analysis of dynamic behavior of elastic continuum moving in liquid. The method of solution is demonstrated on the non-stationatr movement of a bar in a real, incompressible liquid. The principle of the solution is based on the modal transformation of the bar and discrete process using the finite element method (FEM). The problem is in general non-linear. However, the method introduced in this contribution allows the solution which provides gradual separation of the movement of liquid and the movement of the bar. This substitution is entered analogously on the finite element and is dependent on the normal coordinates. The result is a tensor of additional effects. and Obsahuje seznam literatury
This paper presents a variant of a mathematical model of continuum mechanics. Adaption of the model is focused on the unsteady term. The solution is based on the assumption of the zero value of the divergence vector, which can have a different physical meaning. and Obsahuje seznam literatury a názvosloví
In this paper we present new approach to the problem of conservation the small and endangered populations of black grouse. We elaborated and checked in the field non-invasive methods enabling to obtain the genetic material without removing birds from natal populations. The main idea is to mate the tame, especially accustomed hen from the aviary with wild cock. After mating the hen lays the eggs in the aviary and we obtain the first generation which has a half of the gene pool coming from the population of its father. Consecutive, repeated crossing the females from such broods with next wild males leads in few years to bring the genes from original population to the aviary in non-invasive manner. Another method is to collect semen from wild males using a stuffed female. We describe some technical methods of such manipulations with the birds and present some preliminary results. These methods enable obtaining birds bred in aviary for future program of reintroduction.
In this study we are adding further information to phylogeography of Pipistrellus pipistrellus complex by discovery of isolated mitochondrial lineages in Europe, from the island of Crete (Greece) and central Mediterranean (Sicily, Corsica) and by adding new data about geographic distribution of clades within the complex. We performed phylogeographic study with aid of partial sequence of cytochrome b and with focus to the radiation centre of this group in the Mediterranean Basin. Within the clade P. pygmaeus s.l., we have discovered isolated lineage from Crete, which is sister taxon to P. hanaki from Libya. We have detected the occurrence of P. pygmaeus s.str. in northern Iran. In the clade P. pipistrellus s.l. we have discovered isolated cluster represented by populations from Sicily and Corsica, with phylogenetic relation to Moroccan lineage. This is a first evidence of separated phylogroup within the complex from central Mediterranean. We refer the occurrence of P. pipistrellus s.str. from the island of Cyprus. These data represent further arguments for importance of the Mediterranean region in phylogeny of the P. pipistrellus species complex. Proposed allopatric speciation scenario considers the role of environmental fragmentation during the Messinian Salinity Crisis, strengthen by preference of mountain habitats in Mediterranean populations. The species status of Cretan and central Mediterraenan forms is also discussed.
First-stage larvae of camallanid nematodes Procamallanus (Procamallanus) laeviconchus (Wedl, 1862) and Procamallanus (Procamallanus) sp. from naturally infected Distichodus niloticus (Hasselquist) and Clarias gariepinus (Burchell), respectively, from Lake Turkana, Kenya (new geographical records) are described, being for the first time studied by scanning electron microscopy. Larvae of both species are characterised by the presence of a dorsal cephalic tooth, four submedian cephalic papillae and a pair of amphids, and by the elongate tail with several terminal digit-like processes. The latter formations probably serve for the attachment of larvae to the substrate in water when the larvae attract copepod intermediate hosts by their movements; these structures, especially their numbers, may be of taxonomic importance in camallanid nematodes.
Examination of the type material of Progrillotia dollfusi Carvajal et Rego, 1983, and of new specimens recently collected off the coast of Argentina (including plerocerci from 10 species of teleosts and adults from Squatina guggenheim Marini), allowed a detailed redescription of this species and the evaluation of its current taxonomic status. The following characters that have been treated inconsistently by different authors have been herein corrected or confirmed: band of hooklets on external surface restricted to the base of the tentacle, external surface of metabasal region with 3-5 intercalary hooks arranged in a single row merging immediately to a cluster of 3-4 hooklets arranged in two rows; retractor muscle originating in the posterior third of the bulb, hollow hooks, and posterior margin of bothria notched. These features along with the presence of postovarian testes in the adults clearly confirm the placement of P. dollfusi in the genus Grillotia Guiart, 1927. In order to avoid the homonymy with Grillotia dollfusi Carvajal, 1971, a new name, Grillotia carvajalregorum nom. n., is proposed. This species differs from the 16 valid species in the genus in the combination of the following characters: number and morphology of hooks in principal rows in proximal metabasal region of the tentacle, number and distribution of intercalary hooks, presence of clusters of hooklets, extent of band of hooklets on external surface of basal armature, site of origin of the retractor muscle, and features of the terminal genitalia. The present study describes the plerocerci and adult worms, and provides detailed description of the microthrix pattern and histology of this species for the first time.