a1_Vascular resistance in the mammalian pulmonary circulation is affected by many endogenous agents that influence vascular smooth muscle, right ventricular myocardium, endothelial function, collagen and elastin deposition, and fluid balance. When the balance of these agents is disturbed, e.g. by airway hypoxia from high altitude or pulmonary obstructive disorders, pulmonary hypertension ensues, as characterized by elevated pulmonary artery pressure (PPA). Among neuropeptides with local pulmonary artery pressor effects are endothelin-1 (ET-1), angiotensin II (AII), and substance P, and among mitigating peptides are calcitonin gene-related peptide (CGRP), adrenomedullin (ADM), atrial natriuretic peptide (ANP), vasoactive intestinal peptide (VIP) and ET-3. Moreover, somatostatin28 (SOM28) exacerbates, whereas SOM14 decreases PPA in hypoxic rats, with lowering and increasing of lung CGRP levels, respectively. Pressure can also be modulated by increasing or decreasing plasma volume (VIP and ANP, respectively), or by induction or suppression of vascular tissue remodeling (ET-1 and CGRP, respectively). Peptide bioavailability and potency can be regulated through hypoxic up- and down- regulation of synthesis or release, activation by converting enzymes (ACE for AII and ECE for ET-1), inactivation by neutral endopeptidase and proteases, or by interaction with nitric oxide (NO). Moreover, altered receptor density and affinity can account for changed peptide efficacy. For example, upregulation of ETA receptors and ET-1 synthesis occurs in the hypoxic lung concomitantly with reduced CGRP release. Also, receptor activity modifying protein 2 (RAMP2) has been shown to confer ADM affinity to the pulmonary calcitonin-receptor-like receptor (CRLR). We recently detected the mRNA encoding for RAMP2, CRLR, and the CGRP receptor RDC-1 in rat lung., a2_The search for an effective, lung selective treatment of pulmonary hypertension will likely benefit from exploring the imbalance and restoring the balance between these native modulators of intrapulmonary pressure. For example, blocking of the ET-1 receptor ETA and vasodilation by supplemental CGRP delivered i. v. or via airway gene transfer, have proven to be useful experimentally., I. M. Keith., and Obsahuje bibliografii
Recent studies focused on epicardial fat, formerly relatively neglected component of the heart, have elucidated some of its key roles. It possesses several properties that can distinguish it from other adipose tissue depots. Its unique anatomical location in the heart predisposes the epicardial fat to be an important player in the physiological and biochemical regulation o f cardiac homeostasis. Obesity is associated with an increase in epicardial fat mass. Excess of cardiac fat can contribute to greater left ventricular mass and work, diastolic dysfunction and attenuated septal wall thickening. Imbalance in adipokines levels secreted in autocrine or paracrine fashion by epicardial fat can contribute to the activation of the key atherogenic pathways in the setting of metabolic syndrome. Epicardial fat has also been identified as an important source of pro-inflammatory mediato rs worsening endothelial dysfunction, eventually leading to coronary artery disease. Increased production of pro-inflammatory factors by epicardial fat can also contribute to systemic insulin resistance in patients undergoing cardiac surgery. Here we revie w the most important roles of epicardial fat with respect to heart disease in the context of other underlying pathologies such as obesity and type 2 diabetes mellitus., Z. Matloch, T. Kotulák, M. Haluzík., and Obsahuje bibliografii
We hypothesize that differences in fungal taxonomic groups may exert a direct influence on the composition of mycophagous insect communities, and that the relative importance of taxonomy compared to other fungal traits may change as the mushrooms decay. We conducted a 3-year field survey and analyzed the species composition of mycophagous insect communities using partial canonical correspondence analysis (partial CCA). We collected 2457 mushrooms belonging to 27 genera, and 4616 insects belonging to 16 families emerged from 439 of the mushrooms. For the whole insect community, fungal genera explained 10-19% of the total variance in the family composition of the insect communities of mushrooms at different developmental stages. Only the fungal genus Collybia significantly affected the community composition almost irrespective of developmental stage. In the drosophilid community, which consisted of 844 individuals from 9 species, fungal genera explained 19-34% of the total variance. Some fungal genera, such as Amanita and Collybia, affected the drosophilid community, but not at all developmental stages. The number of fungal genera that significantly affected the insect community composition did not differ among fungal stages both in the whole insect community and in the drosophilid community. Thus, our former hypothesis was supported by the present analysis, whereas the latter was not. However, the percentages of variance explained by fungal genera were rather small. This suggests that the importance of fungal genera is likely to be less significant than that of other selection pressures in determining the species composition of mycophagous insect communities.
Gastrointestinal hormones play an important role in the neuroendocrine regulation of food intake and postprandial satiety. Ghrelin is a 28-amino acid orexigenic peptide produced mainly by the stomach that is involved in both the long-term regulation of body weight and the short-term regulation of postprandial satiety. Impairments in ghrelin secretion may in concert with other factors play an important role in the development of both obesity and anorexia nervosa. Despite an intensive research the critical factors regulating physiological postprandial ghrelin response in healthy individuals and its modification by the presence of obesity and anorexia nervosa are only partially understood. The potential contribution of ghrelin to the differences of diet- vs. surgical-induced weight losses in morbidly obese patients is now also being recognized. The aim of this review is to summarize the current knowledge about the physiology and pathophysiology of ghrelin and to discuss its potential in the prevention and/or treatment of obesity and anorexia nervosa., I. Dostálová, M. Haluzík., and Obsahuje seznam literatury
An understanding of preferential flow in the vadose zone is crucial for the prediction of the fate of pollutants.
Infiltration basins, developed to mitigate the adverse effects of impervious surfaces in urban areas, are established above
strongly heterogeneous and highly permeable deposits and thus are prone to preferential flow and enhanced pollutant
transport. This study numerically investigates the establishment of preferential flow in an infiltration basin in the Lyon
suburbs (France) established over a highly heterogeneous glaciofluvial deposit covering much of the Lyon region. An investigation
of the soil transect (13.5 m long and 2.5 m deep) provided full characterization of lithology and hydraulic
properties of present lithofacies. Numerical modeling with the HYDRUS-2D model of water flow in the transect was
used to identify the effects of individual lithofacies that constitute the deposit. Multiple scenarios that considered different
levels of heterogeneity were evaluated. Preferential flow was studied for several values of infiltration rates applied
after a long dry period. The numerical study shows that the high contrast in hydraulic properties of different lithofacies
triggers the establishment of preferential flow (capillary barriers and funneled flow). Preferential flow develops mainly
for low water fluxes imposed at the surface. The role of individual lithofacies in triggering preferential flow depends on
their shapes (layering versus inclusions) and their sizes. While lenses and inclusions produce preferential flow pathways,
the presence of the surface layer has no effect on the development of preferential flow and it only affects the effective
hydraulic conductivity of the heterogeneous transect.
This paper looks at housing strategy in a wider social and economic context and argues that a household’s (class) position in society depends on important life decisions, one of the most important of which is a person’s employment strategy and preparation for the period of retirement (pensions), which is related to housing decisions. The main context of these decisions is the welfare regime, but also a country’s economic structure (varieties of capitalism) and housing system (tax and subsidy elements of programmes). However, as the paper argues, these systems are also changing in relation to the macro effect of individual decisions.
Wound healing is a complex physiological process important for tissue homeostasis. An acute injury initiates massive cell migration, proliferation and differentiation, synthesis of extracellular matrix components, scar formation and remodelling. Blood flow and tissue oxygenation are parts of the complex regulation of healing. Higher organisms utilize molecular oxygen as a terminal oxidant. This way of gaining energy for vital processes such as healing leads to the production of a number of oxygen compounds that may have a defensive or informatory role. They may be harmful when present in high concentrations. Both the lack and the excess of reactive oxygen species may influence healing negatively., Jiří Kanta, and Literatura 6
Cardiovascular studies have confirmed that hydrogen sulphide (H2S) is involved in various signaling pathways in both physiological and pathological conditions, including hypertension. In contrast to nitric oxide (NO), which has a clear vasorelaxant action, H2S has both vasorelaxing and vasoconstricting effects on the cardiovascular system. H2S is an important antihypertensive agent, and the reduced production of H2S and the
alterations in its functions are involved in the initiation of spontaneous
hypertension. Moreover, cross-talk between H2S and NO has been reported. NO-H2S interactions include reactions between the molecules themselves, and each has been shown to regulate the endogenous production of the other. In addition, NO and H2S can interact to form a nitrosothiol/s complex, which has original properties and represents a novel nitroso-sulphide signaling pathway. Furthermore, recent results have shown that the interaction between H2S and NO could be involved in the endothelium-regulated compensatory mechanisms that are observed in juvenile spontaneously hypertensive rats. The present review is devoted to role of H2S in vascular tone regulation. We primarily focus on the mechanisms of H2S-NO interactions and on the role of H2S in blood pressure regulation in normotensive and spontaneously hypertensive rats.
Ferritin and increased iron stores first appea red on the list of cardiovascular risk factors more than 30 years ago and their causal role in the pathogenesis of atherosclerosis has been heavily discussed since the early 1990s. It seems that besides traditional factors such as hyperlipoprotein emia, hyp ertension, diabetes mellitus, obesity, physical inactivity, smoking and family history, high iron stores represent an additional parameter that could modify individual cardiovascular risk. The role of iron in the pathogenesis of atherosclerosis was origina lly primarily associated with its ability to cataly ze the formation of highly reactive free oxygen radicals and the oxidation of atherogenic lipoproteins. Later, it became clear that the mechanism is more complex. Atherosclerosis is a chronic fibroprolife rative inflammatory process and iron, through increased oxidation stress as well as directly, can control both native and adaptive immune responses. Within the arterial wall, iron affects all of the cell types that participate in the atherosclerotic proces s (monocytes/macrophages, endothelial cells, vascular smooth muscle cells and platelets). Most intracellular iron is bound in ferritin, whereas redox-active iron forms labile iron pool. Pro-inflammatory and anti-inflammatory macrophages within arterial plaque differ with regard to the amount of intracellular iron and most probably with regard to their labile iron pool. Yet, the relation between plasma ferritin and intracellular labile iro n pool has not been fully clarified. Data from population studies document that the consumption of meat and lack of physical activity contribute to increased iron stores. Patients with hereditary h emochromatosis, despite extreme iron storage, do not show i ncreased manifestation of atherosclerosis probably due to the low expression of hepcidin in macrophages., P. Kraml., and Obsahuje bibliografii