Regulace příjmu potravy a nutričního stavu organismu je komplexní děj, který se odehrává na úrovni několika orgánových systémů. Centrálním regulátorem je hypothalamus, který integruje nervové a hormonální signály z periferie a monitoruje sérové hladiny glukózy a lipidů. V hypothalamu se nacházejí neurony produkující jak orexigenní hormony zvyšující příjem potravy (neuropeptid Y, agouti-related protein, orexiny), tak anorexigenní hormony, které působí opačným mechanismem (proopiomelanokortin, kokainem a amfetaminem regulovaný transkript). Gastrointestinální trakt je místem produkce především anorexigenních regulačních hormonů (cholecystokinin, oxyntomodulin, bombesin), které zpětnovazebně prostřednictvím cirkulace a vagových zakončení ovlivňují hypothalamická centra. Jediným orexigenním peptidem tvořeným v trávicím traktu je ghrelin. Pankreatické hormony (inzulin, pankreatický polypeptid, amylin), které ovlivňují glukózový metabolismus, regulují také příjem potravy a nutriční stav organismu přímým působením na CNS i nepřímo prostřednictvím ovlivnění glykémie. Pohled na tukovou tkáň jako na pasivní úložiště energie je již překonán. Adipocyty produkují řadu hormonálně aktivních látek, které se podílejí jak na regulaci tělesné hmotnosti (leptin), tak insulinové senzitivity (adiponektin, rezistin). Sérové hladiny uvedených regulačních hormonů reagují dynamicky jak na příjem potravy, tak na celkový nutriční stav organismu. Jejich periferní nebo centrální aplikace působí změnu příjmu potravy a u některých z nich byla již vyvinuta syntetická analoga, u kterých se předpokládá využití v léčbě poruch výživy u člověka. Proto jsou tyto hormony vhodné ke studiu z pohledu klinické biochemie jako potencionální biomarkery., Regulation of food intake and nutritional status is a complex process which takes place in several organ systems. Hypothalamus is the central regulator that integrates signals from the nervous system and peripheral hormones and monitors serum levels of glucose and lipids. In the hypothalamus, there are neurons producing both orexigenic hormones that increase food intake (neuropeptide Y, agouti-related protein, orexins), and anorexigenic hormones, that act in antagonistic way (proopiomelanocortin, cocaine- and amphetamine-regulated transcript). Gastrointestinal tract is mainly the source of anorexigenic regulatory hormones (cholecystokinin, oxyntomodulin, bombesin), that influence hypothalamic centres by both circulation and vagal nerves. The only orexigenic peptide produced by gastrointestinal tract is ghrelin. Pancreatic hormones (insulin, pancreatic polypeptide, amylin), that influence glucose metabolism, regulate also food intake and nutritional status of the organism both by direct action on CNS and indirectly through changes of glycaemia. Adipose tissue is not considered a passive place of energy stores anymore. Adipocytes produce quite a number of hormonally active substances that participate in the regulation of body weight (leptin), and insulin sensitivity (adiponectin, resistin). Serum levels of above-mentioned regulatory hormones are dynamically influenced both by food intake, and general nutritional status of the organism. Peripheral or central administration leads to changes in food intake and for some of them synthetic analogues are being developed with potential future use in treatment of nutritional disorders. Thus, these hormones are suitable for studies in the field of clinical biochemistry as potential biomarkers., Jiří Bronský, Richard Průša, and Lit.: 35
Many extracellular signals are at the cell surface received by specific receptors, which upon activation transduce information to the appropriate cellular effector molecules via trimeric G proteins. The G protein-mediated cascades ultimately lead to the highly refined regulation of systems such as sensory perception, cell growth, and hormonal regulation. Transmembrane signaling may be seriously deranged in various pathophysiological conditions. Over the last two decades the major experimental effort of our group has been devoted to better understanding the molecular mechanisms underlying transmembrane signaling regulated by G proteins and to the closely related process of desensitization of hormone response. This review provides general information about the basic principles of G protein-regulated transmembrane signaling as well as about our contribution to the current progress in the field.
Spinal cord injury results in a permanent neurological deficit due to tissue damage. Such a lesion is a barrier for “communication” between the brain and peripheral tissues, effectors as well as receptors. One of the primary goal s of tissue engineering is to bridge the spinal cord injury and re-establish the damaged connections. Hydrogels are biocompatible implants used in spinal cord injury repair. They can create a permissive environment and bridge the lesion cavities by providing a scaffold for the regeneration of neurons and their axons, glia and other tissue elements. The advantage of using artificial materials is the possibility to modify their physical and chemical properties in order to develop the best implant suitable for spinal cord injury repair. As a result, several types of hydrogels have been tested in experimental studies so far. We review our work that has been done during the last 5 years with various types of hydrogels and their applications in experimental spinal cord injury repair., A. Hejčl, P. Lesný, M. Přádný, J. Michálek, P. Jendelová, J. Štulík, E. Syková., and Obsahuje bibliografii a bibliografické odkazy
This paper examines the changes in the species composition of aphids living in dry calcareous grasslands in Central Europe over a 25-year period. To the best of our knowledge, this is the first analysis of this type in the world that takes into account both previous and current data on species richness as well as groups of aphids that are distinguishable on the basis of biological and ecological criteria such as host-alternation and feeding types, life cycle, ecological niche, symbiosis with ants and their ecological functional groups. Over the period of more than 25 years, there has been a significant decrease in aphid α-diversity, from 171 to 105 species. The gain, which is in species not previously recorded, was 17 taxa. The loss of biodiversity occurred despite the fact that these habitats are protected and are valuable regional biodiversity hotspots. The losses are mostly related to intensive human activity in adjacent areas, which, unfortunately, has resulted in the isolation of these small, protected environmental islands by the removal of ecological corridors. Since, as is shown in this study, the frequencies between individual biological and ecological groups of aphids have been retained, it would be possible to restrict this loss of biodiversity if appropriate actions are taken., Barbara Osiadacz, Roman Hałaj, Damian Chmura., and Obsahuje bibliografii
Over the last two decades my colleagues and I have assembled the literature on a good percentage of most of the coccidians (Conoidasida) known, to date, to parasitise: Amphibia, four major lineages of Reptilia (Amphisbaenia, Chelonia, Crocodylia, Serpentes), and seven major orders in the Mammalia (Carnivora, Chiroptera, Lagomorpha, Insectivora, Marsupialia, Primates, Scandentia). These vertebrates, combined, comprise about 15,225 species; only about 899 (5.8%) of them have been surveyed for coccidia and 1,946 apicomplexan valid species names or other forms are recorded in the literature. Based on these compilations and other factors, I extrapolated that there yet may be an additional 31,381 new apicomplexans still to be discovered in just these 12 vertebrate groups. Extending the concept to all of the other extant vertebrates on Earth; i.e. lizards (6,300 spp.), rodents plus 12 minor orders of mammals (3,180 spp.), birds (10,000 spp.), and fishes (33,000 spp.) and, conservatively assuming only two unique apicomplexan species per each vertebrate host species, I extrapolate and extend my prediction that we may eventually find 135,000 new apicomplexans that still need discovery and to be described in and from those vertebrates that have not yet been examined for them! Even doubling that number is a significant underestimation in my opinion.
Biofeedback is a treatment technique in which people are trained to improve their physiological functions by using different signals from their own bodies, e.g. from skin, heart (ECG), muscles (EMG), brain (EEG) etc. Psychotherapeutists use it to decrease intrapsychic tension in anxious and depressive patients and epileptics or learn to relax boys who suffered from attention deficit and hyperactivity disorders. The main system for consciousness (thalamocortical reverberation circuit) generates whole brain electromagnetic frequencies permanently (1-30 Hz = EEG activity). But we choose a specific frequency band, e.g. SMR (Sensory Motor Rhythm = 13-18 Hz) and these SMR episodes are rewarded by success in a simultaneously watched TV game. SMR is then repeated still more often and brings into electrogenesis and into psyche tendency its own property, which is motor inhibition and increasing attention. This is the aim of the therapeutical learning process.
Eukaryotic cytochrome c oxidase (CcO), the terminal component of the mitochondrial electron transport chain is a heterooligomeric complex that belongs to the superfamily of heme-copper containing terminal oxidases. The enzyme, composed of both mitochondrially and nuclear encoded subunits, is embedded in the inner mitochondrial membrane, where it catalyzes the transfer of electrons form reduced cytochrome c to dioxygen, coupling this reaction with vectorial proton pumping across the inner membrane. Due to the complexity of the enzyme, the biogenesis of CcO involves a multiplicity of steps, carried out by a number of highly specific gene products. These include mainly proteins that mediate the delivery and insertion of copper ions, synthesis and incorporation of heme moieties and membrane-insertion and topogenesis of constituent protein subunits. Isolated CcO deficiency represents one of the most frequently recognized causes of respiratory chain defects in humans, associated with severe, often fatal clinical phenotype. Here we review recent advancements in the understanding of this intricate process, with a focus on mammalian enzyme.
Vascular flora of 71 artificial islands of varying agewas analyzed in 22 fishponds, Třeboň Basin, the Czech Republic. Data on species richness were interpreted in terms of Wilson’s (1969) hypothesis on the development of biotic communities. An increase in species richness during the non-interactive stage (one to two years) and a decrease in the interactive stage (three to six years) were both statistically significant. As predicted, by Wilson’s hypothesis, there was also an increase in species richness in the assortative stage (seven to >50 years), however, this trend was not significant. This successional pattern was confirmed by the vegetation development recorded on 34 re-sampled islands. For these islands the positive change in species richness during the assortative stage was significant based on both paired t- and binomial tests. Contributions of island area, elevation, and isolation during individual successional stages were evaluated. As a whole, this is probably the first clear confirmation of Wilson’s hypothesis for vascular plant communities on islands.
Species–area relationships and nestedness patterns were studied in three groups of small terrestrial vertebrates (mammals, reptiles, amphibians) on 14 landbridge islands of the eastern Adriatic. Islands ranged in surface area between 15 and 410 km2 and contained from eight to 36 species from a total species pool of 48. Reptiles were the most species rich group (S = 28), and had more species than mammals (S = 13) and amphibians (S = 7) combined. Island surface area predicted species richness best in reptiles (r2 = 0.79) and most poorly in amphibians (r2 = 0.52). Mammals showed a significantly lower slope of the species–area curve than amphibians and reptiles, and thus accumulated species counts with increase in area at the lowest rate. Nestedness patterns in all groups were significantly more organised than expected by chance. Amphibian nested structure points to extinction dominated and well insularised populations with no subsequent recolonisations. Frequent unexpected presences and absences in the nestedness patterns of mammals and reptiles suggest complex biogeographic histories for these two groups, with several factors putatively in operation: heterogeneity in habitats and the original source fauna, post- isolation immigrations and differential extinction rate due to human-caused habitat degradation.
The tenebrionid beetles on 25 circum-Sicilian islands were studied to determine the influence of island geographical and landscape features on three main intercorrelated biogeographical patterns: (1) species richness, studied using species-area and species environment relationships, (2) species assemblage composition, investigated using Canonical Correspondence Analysis (CCA), and (3) inter-site faunal similarity, investigated using Canonical Correlation Analysis (CANCOR) applied to multidimensional scaling of inter-island faunal dissimilarities. Species richness was mostly influenced by island area and landscape heterogeneity (expressed using various indices of diversity based on land cover categories). When species identities were considered in the CCA, no substantial effect of landscape was detected. Current island isolation did not have a strong influence on species richness, but has a distinct effect in determining species assortments on the remotest islands. Historical influences of Pleistocene landbridge connections were not detectable in species richness relationships using geographical variables in species richness analyses or in assemblage gradients in the CCA, but emerged distinctly from inter-island similarities in the CANCOR. and Simone Fattorini.