Proximal resistance vessels, such as the mesenteric arteries, contribute substantially to the peripheral resistance. The reactivity of resistance vessels to vasoactive substance like natriuretic peptides plays an important role in the regulation of blood pressure. In current study, we investigated the reactivity of mesenteric arteries to atrial natriuretic peptide (ANP), a well known vasodilating factor, in spontaneously hypertensive rats (SHR), as well as the effects of exercise training on it. As a result, ANP-induced vasorelaxation was attenuated in SHR with significantly increased phosphodiesterase type 5 (PDE5), and decreased cGMP/ANP ratio, compared with WKY rats as control. Intriguingly, the decreased reactivity to ANP in SHR was markedly reversed by exercise training. In addition, ANP resistance of in vitro mesenteric arteries was diminished by sildenafil a potent selective inhibitor of PDE5. In conclusion, ANP resistance occurs in resistance vessels of SHR, suggesting predisposition to hypertension, which can be reversed by exercise., Jun Yu, Bing Zhang, Xing-Lu Su, Ru Tie, Pan Chang, Xue-Ce Zhang, Jian-Bang Wang, Ge Zhao, Miao-Zhang Zhu, Hai-Feng Zhang, Bao-Ying Chen., and Obsahuje bibliografii
Renal medullary endothelin B receptors (ETB) mediate sodium excretion and blood pressure (BP) control. Several animal models of hypertension have impaired renal medullary ETB function. We found that 4-week high-caloric diet elevated systolic BP in Dahl salt-sensitive (Dahl S) rats (126±2 vs. 143±3 mm Hg, p<0.05). We hypothesized that renal medullary ETB function is dysfunctional in DS rats fed a high-caloric diet. We compared the diuretic and natriuretic response to intramedullary infusion of ETB agonist sarafotoxin 6c (S6c) in DS rats fed either a normal or high-caloric diet for 4 weeks. Urine was collected during intramedullary infusion of saline for baseline collection followed by intramedullary infusion of either saline or S6c. We first examined the ETB function in DS rats fed a normal diet. S6c increased urine flow (2.7±0.3 μl/min during baseline vs. 5.1±0.6 μl/min after S6c; p<0.05; n=5) and sodium excretion (0.28±0.05 vs. 0.81±0.17 μmol/min; p<0.05), suggesting that DS rats have renal medullary ETB function. However, DS rats fed a high-caloric diet displayed a significant increase in urine flow (2.7±0.4 vs. 4.2±0.4 μl/min, baseline vs. S6c infusion, respectively; p<0.05, n=6), but no significant change in sodium excretion in response to S6c (0.32±0.06 vs. 0.45±0.10 μmol/min). These data demonstrate that renal medullary ETB function is impaired in DS rats fed a high-caloric diet, which may be contributed to the elevation of blood pressure during high-caloric feeding in this model., W. Kittikulsuth, K. A. Hyndman, J. S. Pollock, D. M. Pollock., and Seznam literatury
A natural $T$-function on a natural bundle $F$ is a natural operator transforming vector fields on a manifold $M$ into functions on $FM$. For any Weil algebra $A$ satisfying $\dim M \ge {\mathrm width}(A)+1$ we determine all natural $T$-functions on $T^*T^AM$, the cotangent bundle to a Weil bundle $T^AM$.
Areas built by Neogene volcanic complexes are located in the central and eastern part of Slovakia covering about 10 % of the territory. They belong to the Inner Western Carpathians. The research was divided into two phases. In the first one, primary data from the Geochemical atlas of SR concerning groundwater from neovolcanic complexes were statistically processed and analyzed. In the second phase, field and laboratory methods, methods of classification, statistical and graphical methods were used. The results showed that the chemical composition and physical properties of groundwater are formed by the character of the rock environment, by the depth of circulation and also by properties of source waters. Main features of chemical composition reflecting the neovolcanic origin of groundwater are low TDS value varying by analyzed samples between 85.82 mg l-1 (Veľká Lehota) and 396.48 mg l-1 (Pukanec), presence of SiO2 in the amounts up to 41.76 mg l-1 (Podzámčok), presence of aggressive CO2 in amounts up to 25.19 mg l-1 (Lučina). Five groundwater chemical types were distinguished. The most frequent was the Ca-MgHCO3-SO4 type. In majority cases only primary compounds of the groundwater composition were found. Only in the case of Remetské Hámre groundwater the anthropogenic compound - nitrates was estimated. and Oblasti budované neogénnymi vulkanickými komplexmi sa na Slovensku vyskytujú v jeho centrálnej a východnej časti, pričom tvoria približne 10 % celkovej rozlohy územia. Geologicky patria k Vnútorným Západným Karpatom. Výskumné práce boli rozložené do dvoch fáz. V prvej z nich boli štatisticky a graficky spracované zdrojové dáta z Geochemického atlasu SR týkajúce sa fyzikálnych vlastností a chemického zloženia podzemných vôd pochádzajúcich z neovulkanických komplexov. V druhej fáze boli vykonané terénne a laboratórne práce, použité klasifikačné, štatistické a grafické metódy na analýzu získaných dát. Výsledky výskumu ukázali, že chemické zloženie a fyzikálne vlastnosti podzemných vôd sú formované charakterom horninového prostredia, hĺbkou obehu a tiež vlastnosťami zdrojových vôd. Hlavnými parametrami odrážajúcimi pôvod podzemnej vody v neovulkanitoch sú nízke hodnoty celkovej mineralizácie, ktoré sa u analyzovaných vôd pohybovali medzi 85,82 mg l-1 (Veľká Lehota) a 396,48 mg l-1 (Pukanec), prítomnosť SiO2 v množstvách až do 41,76 mg l-1 (Podzámčok), prítomnosť agresívneho CO2 v množstvách až do 25,19 mg l-1 (Lučina). Bolo rozlíšených 5 chemických typov podzemných vôd. Najčastejšie sa vyskytoval typ Ca-Mg-HCO3-SO4. Vo väčšine prípadov boli v chemickom zložení podzemných vôd dokumentované iba primárne zložky. Len v prípade podzemnej vody z Remetských Hámrov bola určená antropogénna zložka - dusičnany.
Previously published multidisciplinary studies in the Miramichi and Bouctouche rivers (New Brunswick, Canada) noted significant changes in fish health parameters, including elevated tissue levels of organic contaminants and a wide range of physiological disturbances, in mummichog Fundulus heteroclitus (L.) from a site on the Miramichi River that received bleached kraft pulpmill and municipal effluent. The present study reports differences in the abundance of individual parasite species, as well as parasite infracommunity and component community composition, in mummichog from both rivers. These differences were evaluated in relation to host (size, condition, immune function, tissue organochlorine contaminant levels) and environmental (faecal coliform counts, salinity, temperature) data derived from the previously published studies. Overall, 18 parasite species were identified, the most common of which were Ascocotyle sp. larv., Ornithodiplostomum sp. larv., Posthodiplostomum sp. larv., and Proteocephalus filicollis (Rudolphi, 1802). There were broad differences in parasite community structure and composition between rivers and within rivers, the most prominent pattern being a pronounced difference between sites in the upper and lower estuary of each river that was likely driven by salinity. Mean infracommunity richness was also positively related to faecal coliforms (considered here as a surrogate measure of eutrophication via municipal sewage), and both were highest at the most polluted site. We noted no other significant relationships. Thus our data suggest that the parasite communities in these two estuaries were primarily structured by large upstream / downstream ecological gradients in salinity, and secondarily by eutrophication due to pollution by municipal and industrial effluents. Overall, our results highlight the value of coordinated multidisciplinary studies for understanding the factors that shape parasite abundance and community structure.
Natural and commercial Salix clones differ in their ecophysiological response to Zn stress This study was carried out to determine the effect of different zinc concentrations on the ecophysiological response of Salix clones: four commercial clones (“1962”, “1968”, “Drago”, and “Levante”) selected for short rotation coppice, and one natural clone, “Sacco”, obtained from a contaminated area. Gas exchanges, chlorophyll a fluorescence (JIP-test), relative chlorophyll content, and biometric parameters were measured in plants grown for fifteen days in soil containing Zn concentrations of 0, 300, 750, and 1,500 mg(ZnCl2) kg-1. Ecophysiological response to metal stress differed in dependence on the Zn concentration and clone. At the low Zn concentration (300 mg kg-1), the absence of any significant reductions in parameters investigated indicated an efficient plant homeostasis to maintain the metal content within phytotoxic limits. Stomatal limitation, observed at 750 and 1,500 mg kg-1, which was found in all clones after three days of the treatment, might be caused by indirect effects of metal on guard cells. Among commercial clones, “Drago” was more sensitive to Zn stress, showing inhibition of growth, while “1962” clone showed a downregulation of PSII photochemistry following the slowdown in the Calvin-Benson cycle. On the contrary, the natural Salix clone (“Sacco”) performed better compared to the other clones due to activation of a photosynthetic compensatory mechanism., A. Bernardini, E. Salvatori, S. Di Re, L. Fusaro, G. Nervo, F. Manes., and Obsahuje seznam literatury
The coupled transport of pollutants that are adsorbed to colloidal particles has always been a major topic for environmental sciences due to many unfavorable effects on soils and groundwater. This laboratory column study was conducted under saturated moisture conditions to compare the hydrophobic character of the suspended and mobilized colloids in the percolates released from a wettable subsoil and a water repellent topsoil. Both soils with different organic matter content were analyzed for wettability changes before and after leaching using sessile drop contact angles as well as water and ethanol sorptivity curves, summarized as repellency index. Hydrophobicity of the effluent suspensions was assessed using the C18 adsorption method. Water repellency level of the repellent soil decreased after leaching but remained on a lower level of water repellency, while, the wettable soil remained wettable. The leached colloids from the repellent soil were predominantly hydrophilic and the percentage of the hydrophobic colloid fraction in the effluent did not systematically changed with time. Total colloid release depended on soil carbon stock but not on soil wettability. Our results suggest that due to the respective character of transported colloids a similar co-transport mechanism for pollutants
may occur which does not depend explicitly on soil wettability of the releasing horizon, but could be more affected by total SOM content. Further studies with a wider range of soils are necessary to determine if the dominant hydrophilic character of leached colloids is typical. Due to the mostly hydrophilic colloid character we conclude also that changes in wettability status, i.e. of wettable subsoil horizons due to the leachate, may not necessarily occur very fast, even when the overlaying topsoil is a repellent soil horizon with a high organic matter content.
We obtain the natural diagonal almost product and locally product structures on the total space of the cotangent bundle of a Riemannian manifold. Studying the compatibility and the anti-compatibility relations between the determined structures and a natural diagonal metric, we find the Riemannian almost product (locally product) and the (almost) para-Hermitian cotangent bundles of natural diagonal lift type. Finally, we prove the characterization theorem for the natural diagonal (almost) para-Kählerian structures on the total space of the cotangent bundle.
We investigated the genotypes of Cryptosporidium infecting red squirrels (Sciurus vulgaris L.) in two areas of the Western Alps in Italy. Examination of 141 faecal samples from 70 red squirrels revealed oocysts of Cryptosporidium in 17 animals (24.3%). Based on 18S rRNA gene sequencing, two genotypes of Cryptosporidium species were found: 15 squirrels were positive for the Cryptosporidium ferret genotype and 2 for the Cryptosporidium chipmunk genotype I. The occurrence and intensity of Cryptosporidium infection did not differ between the study areas or sex. More than 85% of the positive animals were adults; however no difference was found between Cryptosporidium infection in the juvenile and adult age groups. Oocysts of the Cryptosporidium ferret genotype measured 5.5 ± 0.3 × 5.2 ± 0.2 µm (shape index 1.06) and the Cryptosporidium chipmunk genotype I 5.8 ± 0.3 × 5.4 ± 0.3 µm (shape index 1.07). Neonatal and adult CD1 and BABL/c mice inoculated with 1 × 103 fresh oocysts of both genotypes did not produce detectable infection.