Angiotensin converting enzyme (ACE) inhibition has been reported to induce regression of hypertrophy in several models of hemodynamic pressure overload. The aim of the present study was to determine whether the ACE inhibitor captopril can reduce hypertrophy of the left ventricle induced by a chronic volume overload and modify collagen composition of the hypertrophied myocardium. Rabbits with four months lasting aortic insufficiency were divided into two groups: treated with captopril (20 mg/kg/day) for five weeks and treated with placebo. The respective control groups were represented by sham-operated animals. Aortic insufficiency induced a decrease of diastolic pressure, an increase of systolic and pulse pressure, hypertrophy of the left and right ventricle, and an increase of hydroxyproline content in the left ventricle without a change of hydroxyproline concentrations in either ventricle. Captopril treatment further enhanced pulse pressure by decreasing diastolic blood pressure. Hypertrophy of the left ventricle, hydroxyproline content and concentration in both ventricles were unaffected by captopril treatment. It is concluded that ACE inhibition did not reverse the left ventricular hypertrophy developed as a result of overload induced by aortic insufficiency. We suggest that mechanisms different from activation of the renin-angiotensin system may play a decisive role in the maintenance of hypertrophy in this particular model of volume hemodynamic overload., F. Šimko, V. Pelouch, J. Kyselovic., and Obsahuje bibliografii
We studied the effects of the H2S donor Na2S on the mean arterial blood pressure (MAP) and heart and breathing rates of anesthetized Wistar rats in the presence and absence of captopril. Bolus administration of Na2S (1-4 μmol/kg) into the right jugular vein transiently decreased heart and increased breathing rates; at 8-30 μmol/kg, Na2S had a biphasic effect, transiently decreasing and increasing MAP, while transiently decreasing heart rate and increasing and decreasing breathing rate. These results may indicate independent mechanisms by which H2S influences MAP and heart and breathing rates. The effect of Na2S in decreasing MAP was less pronounced in the presence of captopril (2 μmol/l), which may indicate that the renin-angiotensin system is partially involved in the Na2S effect. Captopril decreased H2S-induced NO release from S-nitrosoglutathione, which may be related to some biological activities of H2S. These results contribute to the understanding of the effects of H2S on the cardiovascular system., M. Drobná, A. Misak, T. Holland, F. Kristek, M. Grman, L. Tomasova, A. Berenyiova, S. Cacanyiova, K. Ondrias., and Obsahuje bibliografii
Seedling performance may determine plant distribution, especially in water-limited environments. Plants of Caragana korshinskii commonly grow in arid and semiarid areas in northwestern China, and endure water shortage in various ways, but little is known about their performance when water shortage occurs at early growth stages. The water relations, photosynthetic activity, chlorophyll (Chl) content and proline accumulation were determined in 1-year-old seedlings growing in a 1:1 mixture of Loess soil and Perlite and subjected to (1) a water deficit for 20 days and (2) kept adequately watered throughout. The water deficit induced low (-6.1 MPa) predawn leaf water potentials (LWP), but did not induce any leaf abscission. Stomatal conductance (gs), leaf transpiration rate (E), and net photosynthetic rate (PN) decreased immediately following the imposition of the water deficit, while the maximal photochemical efficiency of photosystem II (PSII) (Fv/Fm) and the effective quantum yield of PSII (ΦPSII) decreased 15 days later. An early and rapid decrease in gs, reduced E, increased Chl (a+b) loss, increased the apparent rate of photochemical transport of electrons through PSII (ETR)/PN, as well as a gradual increase in non-photochemical quenching of fluorescence (NPQ) and proline may have contributed to preventing ΦPSII from photodamage. C. korshinskii seedlings used a stress-tolerance strategy, with leaf maintenance providing a clear selective advantage, considering the occasional rainfall events during the growing season. and X. W. Fang ... [et al.].
Článek vychází z přehnaného násilí zjevného v Caravaggiově díle a zkoumá jeho konvenční vysvětlení buď jako službu protireformační ideologii, nebo jako reakci na násilnost veřejných poprav v Caravaggiově době, nebo konečně také jako výsledek Caravaggiovy násilné povahy. Tato tvrzení jsou po prověření otázky „realismu“ Caravaggiových obrazů a jeho předpokládaných antiteoretických zdrojů odmítnuta. Článek poté směřuje k hlavní tezi: dobová teorie poezie jako alternativní kontext pro zobrazení násilí. Autor zkoumá dědictví Horatia, a zejména Aristotela v renesanční poetice a ukazuje, jak reinterpretace jejich textů vedla k paragone mezi násilím v poezii a násilím v malbě. Tvrdí, že Caravaggio přijal výzvu, ačkoliv malířství bylo v mnoha ohledech uměleckým druhem s více omezeními než poezie, a ukázal, že by se mohlo, například v případě zobrazení násilných činů, nabízet jako umění věrohodnější a přesvědčivější. Přitom dospěl k výsledkům, které současní kritikové označovali jako „podivuhodné“ – a autor tvrdí, že určité historické významy tohoto slova poukazovaly na očišťující působení Caravaggiových hrůzných výjevů, přesahujících pouhá ustanovení protireformační ideologie. and The article departs from the excessive violence evident in the art of Caravaggio, examining conventional explanations for it as in the service of the ideology of the Counter-Reformation, or as a response to the violence of public executions in the period, or finally as the product of Caravaggio’s own violent disposition. These arguments are rejected after an examination of the question of the ‘realism’ of Caravaggio’s depictions and its supposed anti-theoretical sources. The article then turns to its central thesis: the contemporary theory of poetry as an alternative context for violent representations. The author examines the legacy of both Horace and most importantly Aristotle in Renaissance poetics, and demonstrates how the reinterpretation of their texts led to a paragone between poetic and painted violence. It is argued that Caravaggio took up the challenge of demonstrating that although painting was a more limited art in many respects than poetry, it could, in the case of the representation of violence acts for example, present itself as an art of greater verisimilitude and conviction. In doing so he arrives at effects that contemporary critics described as ‘marvellous’ – and it is argued that the particular historical meanings of this word alluded to the cathartic effects of Caravaggio’s horrific depictions, exceeding the mere determinations of Counter-Reformation ideology.
In the area of Jumla region in Western Nepal, measurements of saturated leaf net photosynthetic rate (Psat), nitrogen content, leaf fluorescence, carbon isotopic composition, and water status were performed on woody coniferous (Pinus wallichiana, Picea smithiana, Abies spectabilis, Juniperus wallichiana, Taxus baccata), evergreen (Quercus semecarpifolia, Rhododendron campanulatum), and deciduous broadleaved species (Betula utilis, Populus ciliata, Sorbus cuspidata) spreading from 2 400 m up to the treeline at 4 200 m a.s.l. With the exception of J. wallichiana, Psat values were lower in coniferous than broadleaved species. Q. semecarpifolia, that in this area grows above the coniferous belt between 3 000 and 4 000 m, showed the highest Psat at saturating irradiance and the highest leaf N content. This N content was higher and Psat lower than those of evergreen oak species of tempe forests at middle and low altitudes. For all species, Psat and N content were linearly correlated, but instantaneous nitrogen use efficiency was lower than values measured in lowland and temperate plant communities. The values of carbon isotopic composition, estimated by δ13C, showed the same range reported for temperate tree species. The ranking of δ13C values for the different tree types was conifers < evergreen broadleaved<deciduous, suggesting tighter stomatal closure and higher water use efficiency for the evergreen types, confirming trends found elsewhere. No relevant differences of δ13C were found along the altitudinal gradient. Quantum yield of photochemistry at saturating irradiance, measured by leaf fluorescence (δF/Fm'), was highest in J. wallichiana and lowest in T. baccata. Overall, photochemical efficiency was more strongly related to species than to altitude. Interestingly, changes of .δF/Fm' along the altitudinal gradient correlated well with the reported altitudinal distribution of the species. and M. de Lillis, G. Matteucci, R. Valentini.
We examined the carbon budget of young winter wheat plants and their associated microorganisms as affected by a doubling of the atmospheric CO2 concentration (700 µmol mol-1). Plants were grown hydroponically in pre-sterilised sand at a controlled irradiance and temperature regime. Net photosynthesis (PN) and respiration (RD) rates of roots and shoots were measured continuously, plant growth and carbon distribution in the plant-root medium-associated microorganism system were determined destructively in interval-based analyses. PN in elevated CO2 grown plants (EC) was 123% of that in the control (AC) plants when averaged over the whole life span (39-d-old plants, 34 d in EC), but the percentage varied with the developmental stage being 115, 88, and 167% in the pretillering, tillering, and posttillering phase, respectively. There was a transient depression of PN, higher amplitude of day/night fluctuations of the chloroplast starch content, and depression of carbon content in rhizosphere of EC plants during the period of tillering. After 34 d in EC, carbon content in shoots, roots, and in rhizodepositions was enhanced by the factors 1.05, 1.28, and 1.96, respectively. Carbon partitioning between above and belowground biomass was not affected by EC, however, proportionally more C in the belowground partitioning was allocated into the root biomass. Carbon flow from roots to rhizodepositions and rhizosphere microflora was proportional to PN; its fraction in daily assimilated carbon decreased from young (17%) to order (3-4%) plants. and H. Šantrůčková ... [et al.].
In bean (Phaseolus vulgaris L.) seedlings well supplied with water, rates of transpiration (E) and CO2 assimilation (PN) of the primary leaves were measured under blue (BR) or red (RR) irradiance of 150 µmol(photon) m-2 s-1. The leaf conductance to H2O vapour transfer (gH2O), as well as the intercellular concentrations of H2O vapour (ei) and of CO2 (Ci) were calculated. Under BR, gH2O was significantly greater, but PN was lower, and E similar as compared with corresponding values found under RR. The increase of stomata aperture under BR was evident although Ci was higher and ei was lower than under RR. Results agree with the suggestion that BR directly activates guard cell metabolism and in well watered plants determines mainly the stomata aperture. and S. Maleszewski, E. Niemyjska, B. Kozłowska-Szerenos.
The metabolic pathway of primary carbon fixation was studied in a peculiar pennate marine diatom, Haslea ostrearia (Bory) Simonsen, which synthesizes and accumulates a blue pigment known as "marennine". Cells were cultured in a semi-continuous mode under saturating [350 µmol(photon) m-2 s-1] or non-saturating [25 µmol(photon) m-2 s-1] irradiance producing "blue" (BC) and "green" (GC) cells, characterized by high and low marennine accumulation, respectively. Growth, pigment contents (chlorophyll a and marennine), 14C accumulation in the metabolites, and the carbonic anhydrase (CA) activity of the cells were determined during the exponential growth phase. Growth rate and marennine content were closely linked to irradiance during growth: higher irradiance increased both growth rate and marennine content. On the other hand, the Chl a concentration was lower under saturating irradiance. The distribution between the Calvin-Benson (C3) and β-carboxylation (C4) pathways was very different depending on the irradiance during growth. Metabolites of the C3 cycle contained about 70 % of the total fixed radioactivity after 60 s of incorporation into cells cultured under the non-saturating irradiance (GC), but only 47 % under saturating irradiance (BC). At the same time, carbon fixation by β-carboxylation was 24 % in GC versus about 41 % in BC, becoming equal to that in the C3 fixation pathway in the latter. Internal CA activity remained constant, but the periplasmic CA activity was higher under low than high irradiance. and M. Rech, A. Morant-Manceau, G. Tremblin.
During batch culture of Haslea ostrearia the highest carbon (14C) fixation rate was found in vivo in cells that did not accumulate the blue pigment marennine (green form). This fixation rate decreased concomitantly with the accumulation of marennine. In vitro, no phosphoenolpyruvate carboxylase (PEPC) activity was detected, but nearly equivalent activities of ribulose-1,5-bisphosphate carboxylase (RuBPC) and phosphoenolpyruvate carboxykinase (PEPCK) were found in the green form. However, the activity of RuBPC was lower than that of PEPCK during marennine accumulation. In vitro carboxylase activities were strongly inhibited by the addition of a marennine extract. A full description of this inhibition could not be confirmed within the cells because marennine accumulates in small cytoplasmic vesicles. and G. Tremblin, J.-M. Robert.
The neotropical genus Clusia comprises arborescent species exhibiting Crassulacean Acid Metabolism (CAM) as was first reported for a Mexican species, Clusia lundellii. Here, the occurrence of CAM photosynthesis was studied in 20 species of Clusia, 18 from Mexico, and 2 from Guatemala, using leaf carbon isotopic composition. In most species, samples from individuals collected in different locations were analyzed. CAM was present in at least 11 species, eight of which contained specimens with δ13C values less negative than -20.0 ‰, indicating strong CAM (C. chanekiana, C. flava, C. lundellii, C. mexicana, C. quadrangula, C. rosea, C. suborbicularis, and C. tetra-trianthera). δ13C was highly variable in some species, but CAM expression was not correlated to life form (epiphytic, hemiepiphytic, terrestrial) or habitat. CAM specimens were not collected at altitudes above 1 700 m a.s.l. and J. G. Vargas-Soto, J. L. Andrade, K. Winter.