Endogenous regulators, such as angiotensin-II (AngII), endothelin-1 (ET-1) and urotensin-II (U-II) are released from various cell types and their plasma levels are elevated in several cardiovascular diseases. The present study evaluated a potential crosstalk between these systems by investigating if the myocardial effects of U-II are modulated by AngII or ET-1. Effects of U-II (10-8 , 10 -7 , 10 -6 M) were tested in rabbit papillary muscles in the absence and in the presence of losartan (selective AT1 receptor antagonist), PD-145065 ( nonselective ET-1 receptors antagonist), losartan plus PD-145065, AngII or ET-1. U-II promoted concentration-dependent negative inotropic and lusitropic effects that were abolished in all experimental conditions. Also, U-II increased resting muscle length up to 1.008±0.002 L/Lmax. Correcting it to its initial value resulted in a 19.5±3.5 % decrease of resting tension, indicating increased muscle distensibility. This effect on muscle length was completely abolished in the presence of losartan and significantly attenuated by PD-145065 or losartan plus PD-145065. This effect was increased in the presence of AngII, resulting in a 27.5±3.9 % decrease of resting tension, but was unaffected by the presence of ET-1. This study demonstrated an interaction of the U-II system with the AngII and ET-1 systems in terms of regulation of systolic and diastolic function., A. P. Fontes-Sousa ... [et al.]., and Obsahuje seznam literatury
Erythropoietic protoporphyria (EPP) is an inherited disorder of heme biosynthesis caused by partial ferrochelatase deficiency, resulting in protoporphyrin overproduction which is responsible for painful skin photosensitivity. Chronic liver disease is the most severe complication of EPP, requiring liver transplantation in some patients. Data from a
mouse model suggest that cytotoxic bile formation with high concentrations of bile salts and protoporphyrin may cause biliary fibrosis by damaging bile duct epithelium. In humans, cholestasis is a result of intracellular and canalicular precipitation of protoporphyrin. To limit liver damage two strategies may be considered: the first is to reduce protoporphyrin production and the second is to enhance protoporphyrin excretion. Bile salts are known to increase protoporphyrin excretion via the bile, while heme arginate is used to decrease the production of porphyrins in acute attacks of hepatic porphyrias. The Griseofulvin-induced protoporphyria mouse model has been used to study several aspects of human protoporphyria including the effects of bile salts. However,
the best EPP animal model is an ethylnitrosourea-induced point mutation with fully recessive transmission, named ferrochelatase deficiency (Fech
m1Pas). Here we investigate the effect of early ursodesoxycholic acid (UDCA) administration and heme-arginate injections on the ferrochelatase deficient EPP mouse model. In this model UDCA administration and heme-arginate injections do not improve the protoporphyric condition of
Fechm1Pas/Fechm1Pas mice.
In this paper the concept of a fuzzy contraction∗ mapping on a fuzzy metric space is introduced and it is proved that every fuzzy contraction∗ mapping on a complete fuzzy metric space has a unique fixed point.
Computed tomography (CT) is an effective diagnostic modality for three-dimensional imaging of bone structures, including the geometry of their defects. The aim of the study was to create and optimize 3D geometrical and real plastic models of the distal femoral component of the knee with joint surface defects. Input data included CT images of stifle joints in twenty miniature pigs with iatrogenic osteochondrosis-like lesions in medial femoral condyle of the left knee. The animals were examined eight and sixteen weeks after surgery. Philips MX 8000 MX and View workstation were used for scanning parallel plane cross section slices and Cartesian discrete volume creation. On the average, 100 slices were performed in each stifle joint. Slice matrices size was 512 x 512 with slice thickness of 1 mm. Pixel (voxel) size in the slice plane was 0.5 mm (with average accuracy of ± 0.5 mm and typical volume size 512 × 512 × 100 voxels). Three-dimensional processing of CT data and 3D geometrical modelling, using interactive computer graphic system MediTools formerly developed here, consisted of tissue segmentation (raster based method combination and 5 % of manual correction), vectorization by the marching-cubes method, smoothing and decimation. Stifle- joint CT images of three individuals of different body size (small, medium and large) were selected to make the real plastic models of their distal femurs from plaster composite using rapid prototyping technology of Zcorporation. Accuracy of the modeling was ± 0.5 mm. The real plastic models of distal femurs can be used as a template for developing custom made press and fit scaffold implants seeded with mesenchymal stem cells that might be subsequently implanted into iatrogenic joint surface defects for articular cartilage-repair enhancement., P. Krupa, P. Kršek, M. Javorník, O. Dostál, R. Srnec, D. Usvald, P. Proks, H. Kecová, E. Amler, J. Jančář, P. Gál, L. Plánka, A. Nečas., and Obsahuje bibliografii
In the pulmonary circulation, resistive and compliant properties
overlap in the same vessels. Resistance varies nonlinearly with
pressure and flow; this relationship is driven by the elastic
properties of the vessels. Linehan et al. (1982) correlated the
mean pulmonary arterial pressure and mean flow with resistance
using an original equation incorporating the distensibility of the
pulmonary arteries. The goal of this study was to validate this
equation in an in vivo porcine model. In vivo measurements were
acquired in 6 pigs. The distensibility coefficient (DC) was
measured by placing piezo-electric crystals around the pulmonary
artery (PA). In addition to experiments under pulsatile conditions,
a right ventricular (RV) bypass system was used to induce
a continuous pulmonary flow state. The Linehan's equation was
then used to predict the pressure from the flow under continuous
flow conditions. The diameter-derived DC was 2.4 %/mmHg
(±0.4 %), whereas the surface area-based DC was 4.1 %/mmHg
(±0.1 %). An increase in continuous flow was associated with
a constant decrease in resistance, which correlated with the
diameter-based DC (r=-0.8407, p=0.044) and the surface areabased DC (r=-0.8986, p=0.028). In contrast to the Linehan’s
equation, our results showed constant or even decreasing
pressure as flow increased. Using a model of continuous
pulmonary flow induced by an RV assist system, pulmonary
pressure could not be predicted based on the flow using the
Linehan’s equation. Measurements of distensibility based on the
diameter of the PA were inversely correlated with the resistance.
The construction of dams is a significant environmental issue due to its impacts on native fish populations and riparian animals and habitats. The response of otters Lutra lutra Linnaeus, 1758 to such disturbances was evaluated using the Aguieira reservoir (Central Portugal) and its associated tributaries as a model. Visiting rates suggested the presence of resident otters, both in the reservoir and in two of the tributaries. There was a significant negative influence of water level and precipitation in the number of spraints found around the reservoir. Nevertheless, marking behaviour was positively related to substrate and negatively related to vegetation cover, though these variables explained only a small amount of variation in otter signs. In the tributaries, although precipitation also negatively affected the number of otter signs found, the availability of rocks in the riverbed and the presence of refuge had a positive influence in marking behaviour. Prey composition and abundance differed between reservoir and tributaries, but the main otter prey in both systems was the pumpkinseed, which is very abundant in the reservoir. Results demonstrate that otters regularly use the Aguieira reservoir, which provides a good prey base, and the associated tributaries, which provide shelter.
This study appears from an experiment previously carried out in New Zealand white rabbits. Allogenic mesenchymal stem cells (MSCs) were transplanted into an iatrogenically-created defect in the lateral section of the distal physis of the left femur in 10 miniature pigs. The right femur with the same defect served as a control. To transfer MSCs, a freshly prepared porous scaffold was used, based on collagen and chitosan, constituting a compact tube into which MSCs were implanted. The pigs were euthanized four months after the transplantation. On average, the left femur with transplanted MSCs grew more in length (0.56±0.14 cm) compared with right femurs with physeal defect without transplanted MSCs (0.14 ± 0.3 cm). The average angular (valgus) deformity of the left femur had an angle point of 0.78°, following measurement and X-ray examination, whereas in the right femur without transplantation it was 3.7°. The initial results indicate that preventive transplantation of MSCs into a physeal defect may prevent valgus deformity formation and probably also reduce disorders of the longitudinal bone growth. This part of our experiment is significant in the effort to advance MSCs application in human medicine by using pig as a model, which is the next step after experimenting on rabbits., L. Plánka ... [et al.]., and Obsahuje seznam literatury
Reports of wood mouse arboreality are rather scarce outside Britain. I reviewed and analysed 267 visits and 16,456 checks of glirids artificial nest-boxes mounted on trees, in twelve sample areas of Meso- and Supra-Mediterranean woodlands (Sicily, 1995–2005). The wood mouse was recorded only 65 times (0.395%) using the artificial nest-boxes in nine sample areas, and based on this low frequency, the wood mouse can be considered as an occasional dweller of artificial nest-boxes. The resource selection index allowed checking the use respect to the availability of nest-boxes placed at different heights. These were likely reached by climbing the dense understorey and low tree branches up to 5 m, but nest-boxes in the two lower classes (0.5–1.0 and 1.1–1.5 m) were used more than those in the two higher classes (1.6–2.0 and 2.1–5.0 m). ANOVA results suggested that the box use was not related to any particular habitat or sample area feature, and it was slightly more pronounced from March to May. Regardless of their age and sex, individuals mostly exploited nest-boxes placed near the ground (0.5–1.5 m) and generally for 2–3 months. Nonetheless, cases of consecutive use for longer periods and instances of reproduction inside nest-boxes showed that some individuals extended their home range also to the vertical dimension.
To estimate the size of fish taken as prey by piscivorous predators, linear or non-linear relationships between bone measures (pharyngeal, opercula, cleithra, anal and dorsal spine bones, otoliths) and body length were elaborated for eleven Eurasian cyprinid fish species captured in three lakes of Turkey: rudd Scardinius erythrophthalmus, Baltic vimba Vimba vimba, Danube bleak Chalcalburnus chalcoides, gibel carp Carassius gibelio, roach Rutilus rutilus, silver bream Blicca bjoerkna, common carp Cyprinus carpio, chub Leuciscus cephalus, Dnieper chub Petroleuciscus borysthenicus, tench Tinca tinca and tarek Alburnus tarichi (endemic species for Lake Van). All calculated regressions were highly significant, with coefficients of determination >81% in most of cases. The results suggest that the biometric relationships between fish length and some bones (pharyngeal, opercula, cleithra) are well suited for use in prey-predator studies of all the studied species, but otoliths and the dorsal and anal spines can be used for some fish species only (rudd, Baltic vimba, roach, silver bream, gibel carp).
A comparison of the effects of ultrasound produced by low- and high-frequency ultrasonic apparatuses upon biological systems is one of the basic problems when studying ultrasound cavitation effects. One possibility for how to compare these effects is the indirect method which uses well-known physical quantities characterizing the interaction of ionizing radiation with matter and which also converts these quantities to one common physical quantity. The comparison was performed with two methods applied to the chemical dosimetry of ionizing radiation. The first method employed a twocomponent dosimeter which is composed of 50 % chloroform and 50 % re-distilled water (i.e. Taplin dosimeter). The other method used a modified iodide dosimeter prepared from a 0.5 M potassium iodide solution. After irradiation or ultrasound exposure, measurable chemical changes occurred in both dosimeters. The longer the exposure, the greater the chemical changes. These effects are described by the relationship of these changes versus the exposure times in both dosimeters. The UZD 21 ultrasonic disintegrator (with a frequency of 20 kHz, 50 % power output) was used as a lowfrequency ultrasound source, and the BTL-07 therapeutic instrument (with a frequency of 1 MHz and intensity of 2 W/cm2) was used as a high-frequency cavitation ultrasound source. For comparison, a 60Co gamma source was applied (60Co, gamma energies of 1.17 and 1.33 MeV, activity of 14 PBq). Results of this study have demonstrated that the sonochemical products are generated during exposure in the exposed samples of both dosimeters for all apparatuses used. The amount of these products depends linearly upon the exposure time. The resulting cavitation effects were recalculated to a gray-equivalent dose (the proposed unit is cavitation gray [cavitGy]) based on the sonochemical effects compared to the effects of ionizing radiation from the 60Co source., B. Kratochvíl, V. Mornstein., and Obsahuje bibliografii