Recently it has been shown that vitamin D3 acting via its cognate receptor (VDR) regulates the growth, differentiation and function of female reproductive tissues including ovary. The aim of the study was to examine the effect of testosterone (T) and its antagonist 2-hydroxyflutamide (HF) on VDR protein expression and function in porcine ovarian follicles. Medium size antral follicles expressing great amount of androgen receptors and represent high steroidogenic activity were used in this research. After 6 h incubation of whole follicles with T, HF or T+HF, immunohistochemical analysis of VDR revealed its nuclear localization in granulosa and theca interna cells in control and experimental groups. The expression of VDR protein was shown as a band of 48 kDa. There were no significant differences between either experimental group and the control. T influenced the function of VDR through decreased formation of VDR/RXR (retinoid X receptor) complexes (P<0.05) in both granulosa and theca interna cells, but HF abolished this effect only in granulosa cells (P<0.05). These results suggest that androgens regulate the response of follicular cells to vitamin D3 in pigs ovary via regulation of VDR transcriptional activity., M. Herian, M. R. Luck, M. Grzesiak., and Obsahuje bibliografii
The oribatid mite Galumna elimata was reared under laboratory conditions on algae (Protacoccus spp.) at different temperatures (5, 15 and 20°C). Higher weight-specific amylolytic activity was found in the whole body homogenates of mites exposed to cold acclimation (5°C, 21 days) in comparison with individuals acclimated to 15 and 20°C. Accompanying parameters (live body weight, content of total soluble proteins in the body, protein-specific amylolytic activity, presence and composition of food boluses, activity of mesenteric and caecal wall cells, gregarinid parasitisation, number of glycogen granulae and guanine deposits in mesenchymal tissue, presence of proventricular glands) were investigated at all three acclimation temperatures to explain mechanisms of this change. The acclimation response of weight-specific amylolytic activity was accompanied by elevation of protein-specific amy lolytic activity. Microanatomical features did not confirm any increased secretion activity of mesenteric and caecal cells in cold acclimated animals. Granulation and apocrine secretion of these cells increased with increasing temperature as with food ingestion. The food boluses contained algae or algae mixed with unknown fungal hyphae in individuals acclimated to 15 and 20°C. The concentrated mucoid substances prevailed in animals exposed to cold, indicating lower feeding activity at 5°C. Based on these findigs, Lye hypothesised that specific amylolytic activity reflected passively the different changes in protein composition of the body at different temperatures and its elevation is without direct adaptive importance., Vladimír Šustr, Jan Hubert, and Lit
In Phaseolus and Robinia leaves, direct light reaction (de-epoxidatíon of violaxanthín) was inhibited during 7-9 h as an aftereffect of y-radiation (167 mGy s'*). Complete suppression of the light reaction by the de-epoxidation was reached after 12-14 h. The suppression of xanthophyll de-epoxidation reflects the inhibitíon of photosynthetic electron transport chain and may be ušed for testing deleterious efifects on plants.
We investigated the actions of dantrolene Ca2+-induced on Ca2+-release (CICR) evoked by action potentials in cultured rat sensory neurons. The effect of dantrolene on action potential after-depolarization and voltage-activated calcium currents was studied in cultured neonatal rat dorsal root ganglion cells (DRG) using the whole-cell patch-clamp technique. Depolarizing current injection evoked action potentials and depolarizing after-potentials, which are activated as a result of CICR following a single action potential in some cells. The type of after-potentials was determined by inducing action potentials from the resting membrane potential. Extracellular application of dantrolene (10 mM) abolished after-depolarizations without affecting action potential properties. Furthermore, dantrolene significantly reduced repetitive action potentials after depolarizing current injection into these neurons, but had no significant effect on the steady-state current voltage relationship of calcium currents in these neurons. We conclude that dantrolene inhibits the induction of action potential after depolarizations by inhibiting CICR in cultured rat sensory neurons., A. Ayar, H. Kelestimur., and Obsahuje bibliografii
We studied the effect of herbicide and nitrogen supply on photosynthesis in Perilla frutescens L. Britt. Plants were exposed to combined treatment of urea and herbicide, fenoxaprop-P-ethyl (FPE), in various concentrations. FPE reduced significantly chlorophyll (Chl) content, photosynthetic rate, and stomatal conductance, but increased significantly intercellular CO2 concentration; thus, FPE inhibited significantly the photosynthetic capacity. In addition, FPE also decreased significantly the PSII photochemical efficiency, effective quantum yield of photochemical energy conversion in PSII, PSII potential activity, and photochemical quenching of variable Chl fluorescence. It also decreased nonphotochemical quenching. It indicated that FPE impaired PSII and blocked the electron transport in light reaction. The urea treatment at moderate concentration (1-4 g L-1) could antagonize the negative effect of FPE, while the high urea concentration (8 g L-1) aggravated this effect. The treatment with urea (4 g L-1) and then with FPE (1.33 mL L-1) enhanced Chl content index, photosynthetic rate, and stomatal conductance by 12.5, 36.1, and 28.5% compared to FPE treatment alone. Thus, we suggested to treat plants first with urea (4 g L-1) and then by FPE (1.33 mL L-1) as the best and the safest method to balance the fertilization and weeding., J. H. Zhang, S. J. Guo, P. Y. Guo, X. Wang., and Obsahuje bibliografii
ncreased systemic vascular resistance is responsible for blood pressure (BP) elevation in most forms of human or experimental hypertension. The enhanced contractility of structurally remodeled resistance arterioles is mediated by enhanced calcium entry (through L type voltagedependent calcium channels - L-VDCC) and/or augmented calcium sensitization (mediated by RhoA/Rho kinase pathway). It is rather difficult to evaluate separately the role of these two pathways in BP control because BP response to the blockade of either pathway is always dependent on the concomitant activity of the complementary pathway. Moreover, vasoconstrictor systems enhance the activity of both pathways, while vasodilators attenuate them. The basal fasudil-sensitive calcium sensitization determined in rats deprived of endogenous renin-angiotensi n system (RAS) and sympathetic nervous system (SNS) in wh ich calcium entry was dose- dependently increased by L-VDCC opener BAY K8644, is smaller in spontaneously hypertensive rats (SHR) than in normotensive Wistar-Kyoto (WKY) rats. In co ntrast, if endogenous RAS and SNS were present in intact rats, fasudil caused a greater BP fall in SHR than WKY rats. Our in vivo experiments indicated that the endogenous pressor systems (RAS and SNS) augment calcium sensitization mediated by RhoA/Rho kinase pathway, whereas the endogenous vasodilator systems (such as nitric oxide) attenuate this pathway. However, the modulation of calcium entry and calcium sensitization by nitric oxide is strain-dependent because NO deficiency significan tly augments low calcium entry in WKY and low calcium sensitization in SHR. Further in vivo and in vitro experiments should clarify the interrelationships between endogenous vasoactive systems an d the contribution of calcium entry and/or calcium sensitization to BP maintenance in various forms of experimental hypertension., J. Zicha ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Nitric oxide belongs to the most important factors influencing structural and functional properties of vessel wall. Both genetic and environmental factors may influence its metabolism. The aim of this study was to explore whether two common polymorphisms of endothelial nitric synthase (eNOS) may, jointly with smoking, influence the stiffness of large arteries, quantified as pulse wave velocity (PWV). One hundred ninety four subjects free of manifest atherosclerotic disease or chronic pharmacotherapy were selected from population-based postMONICA study. PWV´s were measured using Sphygmocor® device between carotic and femoral arteries (aortic PWV) and between femoral and tibialis-posterior arteries (peripheral PWV). Two common polymorphisms, T786C and G894T, were assessed. Among current smokers, homo- or heterozygous carriers of T786C mutation showed significantly higher peripheral PWV than normal genotype carriers (14.0 vs 10.7 m/s, p<0.002); the same was true for the carriers of G894T mutation (13.9 vs 11.0 m/s, p<0.015). No differences were found in non-smokers, and neither of the eNOS polymorphisms influenced aortic PWV in our setting. In conclusion, genetically determined disorder of nitric oxide metabolism was associated with increased stiffness of peripheral, muscular-type arteries in generally healthy, untreated subjects, but only in the interaction with current smoking., O. Mayer jr. ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
This comparative study of various surface treatments of commercially available implant materials is intended as guidance for orientation among particular surface treatment methods in term of the cell reaction of normal human osteoblasts and blood coagulation. The influence of physicochemical surface parameters such as roughness, surface free energy and wettability on the response of human osteoblasts in the immediate vicinity of implants and on the blood co agulation was studied. The osteoblast proliferation was monitored and the expression of tissue mediators (TNF-α , IL-8, MMP-1, bone alkaline phosphatase, VCAM-1, TGF-β ) was evaluated after the cell cultivation onto a wide range of commercially available materials (titanium and Ti6Al4V alloy with various surface treatments, CrCoMo alloy, zirconium oxide ceramics, polyethylene and carbon/carbon composite). The formation of a blood clot was investigated on the samples immersed in a freshly drawn whole rabbit blood using scanning electron microscope. The surfaces with an increased osteoblast proliferation exhibited particularly higher surface roughness (here Ra > 3.5 μm) followed by a high polar part of the surface free energy whereas the effect of wettability played a minor role. The surface roughness was also the main factor regulating the blood coagulation. The blood clot formation analys is showed a rapid coag ulum formation on the rough titanium-based surfaces. The titanium with an etching treatment was considered as th e most suitable candidate for healing into the bone tissue due to high osteoblast proliferation, the highest production of osteogenesis markers and low production of inflammatory cytokines and due to the most intensive blood clot formation., D. Kubies ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Acetylcholinesterase inhibitors (AChEIs) are used in the treatment of myasthenia gravis (MG). We investigated the effects of AChEIs on peripheral nicotinic receptors (nAChR), which play a crucial role in the treatment of MG symptoms. The positive modulation of those receptors by AChE inhibitors could have an added value to the anti-AChE activity and might be useful in the therapy of MG. Furthermore, to estimate the potential drawbacks of the compounds, cytotoxicity has been assessed on various cell lines. The whole-cell mode of the patch-clamp method was employed. The experiments were performed on medulloblastoma/rhabdomyosarcoma cell line TE671 expressing human embryonic muscle-like receptor with subunits α2βγδ. The effect of the compounds on cell viability was measured by standard MTT assay (Sigma Aldrich) on ACHN (renal cell adenocarcinoma), HeLa (immortal cell line derived from a cervical carcinoma), HEPG2 (hepatocellular carcinoma) and BJ (skin fibroblasts) cell lines. No positive modulation by the tested AChE inhibitors was observed. Moreover, the compounds exhibited antagonistic activity on the peripheral nAChR. Standard drugs used in MG treatment were shown to be less potent inhibitors of muscle-type nAChR than the newly synthesized compounds. The new compounds showed very little effect on cell viability, and toxicities were comparable to standards. Newly synthesized AChEIs inhibited peripheral nAChR. Furthermore, the inhibition was higher than that of standards used for the treatment of MG. They could be used for the study of nAChR function, thanks to their high antagonizing potency and fast recovery of receptor activity after their removal. However, since no positive modulation was observed, the new compounds do not seem to be promising candidates for MG treatment, even though their cytotoxic effect was relatively low., V. Sepsova, J. Krusek, J. Zdarova Karasova, F. Zemek, K. Musilek, K. Kuca, O. Soukup., and Obsahuje bibliografii