Alcohol use has been identified as a risk factor for the development of osteoporosis. Eight male Wistar rats at two months of age were alcoho-fed (7.6 g 95 % ethanol/kg b.w. per day) to evaluate the effects of long-term administration (three months) of alcohol in drinking water. We have used a dose which is considered to be comparable to a dose of 1 liter of wine or 2.5 liters of 12° beer used in male adults daily. The bones were tested mechanically by a three-point bending test in a Mini Bionix (MTS) testing system. The bones from alcohol-fed rats were characterized by a reduction in bone density as well as in ash, calcium and phosphate content. In alcohol-fed rats the reduction in bone mineral density (10 %) was reflected by about 12 % reduction of mechanical strength of femur (158±5.5 vs. 178±3.2 N/mm2). Alcohol significantly altered femoral cortical thickness. In our experiment alcohol itself did not exert any antiandrogenic effect and it did not produce changes in the weight of seminal vesicles. Liver function test (GGT, ALP, AST) did not differ between alcohol-fed rats and control rats. Alcohol-induced bone loss is associated with increased bone resorption and decreased bone formation. These results document the efficacy of alcohol at the dose of 7.6 g 95 % ethanol/kg b.w. to cause bone loss and loss of bone mechanical strength in intact rats. The results of the present study may be interpreted as supporting the hypothesis of alcohol as a risk factor for osteoporosis., P. D. Broulík ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The study has been designed to characterize protein systems involved in the responses of rat hearts to chronic doxorubicin (DOX) treatment. We investigated the influence of DOX on cardiac function, mitogen-activated protein kinases (MAPKs) and heat stress proteins (HSPs). Doxorubicin was administered to rats by intraperitoneal injections over a period of 6 weeks. In control and DOX-treated hearts exposed to 20 min global ischemia and 40 min reperfusion the recovery of contractile function after ischemia/reperfusion (I/R) was determined. The levels and phosphorylation state of proteins in tissue samples were analyzed using specific antibodies. We found an activation of extracellular signal-regulated kinases (ERKs) in rat hearts exposed to DOX treatment and better recovery of contractile function after I/R. Analysis of HSPs showed that DOX induced up-regulation of the levels of HSP60 and down-regulation of HSP70 levels. The levels and/or specific phosphorylation of other studied proteins (p38-MAPK, HSP27, HSP90) were not in fluenced by DOX. The results point to the possible role of ERKs and some HSPs in mechanisms underlying the response of rat hearts to chronic DOX treatment., P. Šimončíková, T. Ravingerová, M. Barančík., and Obsahuje bibliografii a bibliografické odkazy
To find the effects of CO2 enrichment on plant development and photosynthetic capacity of nodulated (line A62-1) and non-nodulated (line A62-2) isogenic lines of soybean (Glycine max Merr.), we examined the interactions among two CO2 treatments (36±3 Pa = AC and 70±5 Pa = EC), and two nitrogen concentrations [0 g(N) m-2(land area) = 0N; 30 g(N) m-2(land area) = 30N]. Nodules were found in both CO2 treatments in 0N of A62-1 where the number and dry mass of nodules increased from AC to EC. While the allocation of dry mass to root and shoot and the amount of N in each organ did not differ between the growth CO2 concentrations, there was larger N allocation to roots in 0N than in 30N for A62-2. The CO2-dependence of net photosynthetic rate
(PN) for A62-1 was unaffected by both CO2 and N treatments. In contrast, the CO2-dependence of PN was lower in 0N than in 30N for A62-2, but it was independent of CO2 treatment. PN per unit N content was unaffected by CO2 concentrations. The leaf area of both soybean lines grown in 30N increased in EC. But in 0N, only the nodulated A62-1 showed an increase in leaf area in EC. Nitrogen use efficiency of plants, NUE [(total dry mass of the plant)/(amount of N accumulated in the plant)] in 30N was unaffected by CO2 treatments. In 0N, NUE in EC was lower than in AC in A62-1, and was higher than that at AC in A62-2. Hence, the larger amount and/or rate of N fixation with the increase of the sink-size of symbiotic microorganisms supplied adequate N to the plant under EC. In EC, N deficiency caused the down-regulation of the soybean plant. and T. Nakamura ... [et al.].
Glucose tolerance, insulin secretion and in vitro insulin action were examined in streptozotocin-induced diabetic rats following pancreatic islet allotransplantation treated with combination of oral cyclosporine A (10 mg/kg) and hydrocortisone (1.5 mg/kg) intramuscularly. 1400 pure islets from multiple donors were implanted either into the portal vein (n = 10) or under the renal capsule (n=ll). Ten sham-operated non-diabetic animals receiving the same immunosuppressive therapy, 8 healthy animals without any treatment and 10 diabetic animals without immunosuppression following islet transplantation were used as controls. In all transplanted animals blood glucose was normalized by day 3 after transplantation with lower levels in those transplanted intraportally (p<0.05). Non-immunosuppressed animals rejected the graft after 6.5±1.2 days after transplantation, lmmunosuppressed animals in both groups remained normoglycaemic till the end of the experiment on day 28. Oral glucose tolerance tests and insulin levels on days 10 and 28 improved dramatically. No differences in glucose and insulin levels between intraportal and subcapsular groups were found. Post-load glucose levels in immunosuppressed non-transplanted animals were higher on day 28 than before treatment and were also higher than in the healthy non-treated group (p<0.05). In vitro insulin action determined by the incorporation of labelled glucose into adipose tissue was impaired only in animals in which islets were transplanted into the liver (p<0.05 vs other groups). In conclusion, therapy with cyclosporine A and hydrocortisone prevents allogeneic islet rejection in rats during a short-term experiment. Although glucose tolerance is not completely normalized following transplantation, slight impairment is also demonstrable in healthy animals on the same drug therapy.
The effects of condensed tannins (CT) extracted from seven forages on the motility of the economically important nematode, Trichostrongylus colubriformis (Giles, 1892), were evaluated by using a larval migration inhibition (I.MI) assay. The assay involved incubation of third stage (L3) exsheathed T. colubriformis larvae with CT extracted from Lotus pedunculatus, Lotus corniculatus, sulla (Hedysarum coronorium), sainfoin (Onobrychis viciifolia), Dorycnium rectum, Dorycnium pentaphyllum and dock (Rumex abtusifolius) and measurement of larval migration through nylon mesh with a 20pm pore size. At 100 pg ml'1, CT from L. pedunculatus, L. corniculatus, sulla, sainfoin, D. rectum, D. pentaphyllum and dock inhibited 20%, 10%, 15%, 25%, 28%, 32% and 27% of the larvae, respectively from passing through the sieves compared to controls (no CT added). At 1000 pg CT ml'1, CT purified from D. pentaphyllum had the highest inhibitory activity (63%) against 1-month old larvae followed by sainfoin (59%), L. pedunculatus (57%), D. rectum (53%), dock (50%), sulla (40%) and L. corniculatus (37%). Seven-month old larvae were more sensitive to the action of CT than 1-month old larvae (P < 0.001). Addition of 2 pg polyethylene glycol ([PHG] per pg CT; to remove the effect of'CT) eliminated 81-93% of the CT activity (P < 0.001) compared to incubations without PEG. The impact of CT on larval migration suggests a possible role for these plants in ruminant diets as a means to reduce dependence upon proprietary anthelmintics.
Factors modulating cardiac susceptibility to ischemia-reperfusion (I/R) are permannetly attracting the attention of experimental cardiology research. We investigated, whether continuous 24 h/day light exposure of rats can modify cardiac response to I/R, NO-synthase (NOS) activity and the level of oxidative load represented by conjugated dienes (CD) concentration. Two groups of male adult Wistar rats were studied: controls exposed to normal light/dark cycle (12 h/day light, 12 h/day dark) and rats exposed to continuous light for 4 weeks. Perfused isolated hearts (Langendorff technique) were exposed to 25 min global ischemia and subsequent 30 min reperfusion. The recovery of functional parameters (coronary flow, left ventricular developed pressure, contractility and relaxation index) during reperfusion as well as the incidence, severity and duration of arrhythmias during first 10 min of reperfusion were determined. The hearts from rats exposed to continuous light showed more rapid recovery of functional parameters but higher incidence, duration and severity of reperfusion arrhythmias compared to controls. In the left ventricle, the NOS activity was attenuated, but the CD concentration was not significantly changed. We conclude that the exposure of rats to continuous light modified cardiac response to I/R. This effect could be at least partially mediated by attenuated NO production., R. Važan, P. Janega, S. Hojná, J. Zicha, F. Šimko, O. Pecháňová, J. Styk, L'. Paulis., and Obsahuje bibliografii
With the gradual increase of coal mining intensity, many coal pillars need to be left near the stope. The stability of the composite structure of coal pillars and their overlying strata determines the safety of the whole stope and the surface. This paper conducts uniaxial compression tests on coal-rock composite structures with the same lithology and the same coal-rock height ratio and finds the coal-rock composite structure’s mechanical properties and failure characteristics have greater discreteness. Combining the CT images of rock and coal, it is concluded that the main reason for the discreteness of the composite structure test results is the different crack characteristics in the rock specimen and the coal specimen. Therefore, this paper uses the PFC numerical simulation software to analyzes the influence of the crack characteristics on the mechanical properties, failure characteristics, and impact energy index of the coal-rock composite structure. The sensitivity factors are used to analyze the influence of crack angle, crack length, crack number and crack position on the peak stress, total crack number, and impact energy index of the coal-rock composite structure. The research results can provide a theoretical basis and guidance for preventing the instability and failure of the coal pillar-roof composite structure.
The aim of this work is to study the behaviour of a crack with its tip at the interface between two polymer materials. A numerical model of a cracked bi-material tension specimen is investigated and different stability criteria are tested. The stability criterion of a general stress concentrator usually needs a relation between the critical value of the generalized stress intensity factor (HIC) and critical value of the stress intensity factor KIC (fracture toughness). This relation is a function of the elastic mismatch of particular mterials; the fracture toughness of the main material and the critical distance d ahead of the stress concentrator, where the criterion is applied. Estimation of distance d is usually not straightforward and different authors use different approaches for its determination. Therefore the main aim of this study is the mutual comparison of published approaches for d estimaton and to quantify the influence of d choice on the critical load value. The results obtained can lead to a better residual lifetime prediction and safer design of layered structures. and Obsahuje seznam literatury
Prolamellar bodies (PLBs) isolated from dark-grown, 6.5-d-old leaves of wheat (Triticum aesíivum L. cv. Kosack) were treated with the carboxylic acid cross-linker l-ethyl-3-[3-(diniethylaniino)propyl]carbodiimide (EDC) or with the lysině specific cross-linker 2-iniinothiolane. SDS-PAGE showed that the most prominenent cross- linked product was a dimer of the NADPH-protochlorophyllide oxidoreductase (PCR), but also larger aggregates of the polypeptide were identified by inununological detection on electro-blots. A two-dimensional diagonál gel showed that much of the cross-linking was between the PCR polypeptides. The cross-linkers induced a shift of the fluorescence peak to shorter wavelengths, a bandwidth increase of the fluorescence peak, and an increase of the fluorescence yield. In the presence of NADPH the blue shift was reduced, but the increase in the fluorescence yield still occmred. A cross-linker treatment of PLBs prior to solubilization with 1-0-n-octyl-P -D-glucopyranoside (octylglucoside) delayed, but did not prevent the spectral shifts from 657 to 646 nm and from 646 to 635 nm observed in non-cross-linked detergent- treated PLBs. The cross-linking did not prevent a spectral shift, corresponding to the Shibata shift, of Chlide. Thus the spectral shifts are not strictly coupled to disaggregation of the PCR polypeptides.