The effect of monovalent cations on trimeric G protein Gi1α was measured at equimolar concentration of chloride anion in pertussis-toxin (PTX)-treated HEK293 cells stably expressing PTX- insensitive DOR-Gi1α (Cys351-Ile351) fusion protein by high-affinity [35S]GTPγS binding assay. The high basal level of binding was detected in absence of DOR ag onist and monovalent ions and this high level was inhibited with the order of: Na+>K+>Li+. The first significant inhibition was detected at 1 mM NaCl. The inhibition by monovalent ions was reversed by increasing concentrations of DOR agonist DADLE. The maximum DADLE response was also highest for sodium and decreased in the order of: Na+>K+≈Li+. Our data indicate i) an inherently high activity of trimeric G protein G i 1 α when expressed within DOR-Gi1α fusion protein and determined in the absence of monovalent cations, ii) preferential sensitivity of DOR-Gi1α to sodium as far as maximum of agonist response is involved., M. Vošahlíková, P. Svoboda., and Obsahuje bibliografii a bibliografické odkazy
The pathophysiological processes underlying the development of diabetic osteopenia has not hitherto been elucidated. Induction of streptozotocin diabetes leads in our experiments to decrease of bone density, ash, mineral content and to thinner cortical width compared to control male rats. In order to investigate the pathogenetic role of bone resorption by osteoclasts in streptozotocin-induced diabetes, we determined the circulating levels of tartrate-resistant acid phosphatase (TRAP), a biochemical marker for bone resorption. Plasma TRAP values in diabetic rats did not differ from their corresponding controls. Streptozotocin diabetes by itself did not have any effect on the weight of seminal vesicles which are highly testosterone-dependent. Low doses of nitric oxide cause bone resorption, but higher doses of NO inhibit bone resorbing activity. We examined the effect of L-NAME (inhibitor of nitric oxide production) after six weeks of administration to diabetic rats. There was no further significant loss of bone mineral density, ash and mineral content or tibia weight in diabetic rats treated with L-NAME. L-NAME itself did not decrease bone metabolism. In our study no evidence of an increased bone resorption was found. Our results have indicated that a predominance of bone resorption over bone formation is not involved in the pathogenesis of diabetes-associated osteopenia. Inhibition of NO neither increased osteoclastic activity (TRAP) nor induced osteopenia in L-NAME-treated rats. This suggests a possibility that NO is not involved in the pathogenesis of diabetic osteopenia., P. D. Broulík, M. Haluzík, J. Škrha., and Obsahuje bibliografii
Increased circulating adhesion molecules in patients with obesity play an important role in the development of endothelial dysfunction/atherosclerosis. The aim of this study was to assess the contribution of various fat depots to the production of adhesion molecules in obesity. 12 women with 1st and 2nd degree of obesity, 13 women with 3rd degree of obesity and 14 lean age-matched women were included into study. Circulating levels of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin were measured by Luminex kits. mRNA expression of ICAM-1, VCAM-1, E-selectin, monocyte chemoattractant protein-1 (MCP-1), and CD68 in subcutaneous (SAT) and visceral adipose tissue (VAT) was measured by RT-PCR; ICAM-1 and VCAM-1 protein levels by Luminex kits, normalized to protein content. Obesity increased ICAM-1 and VCAM-1 mRNA expression and protein levels and CD68 mRNA expression in VAT. Expression of E-selectin and MCP-1 did not significantly differ between groups. Expression of ICAM-1 and VCAM-1 positively correlated with expression of CD68 in both adipose depots. In VAT, ICAM-1 and VCAM-1 expression and protein levels positively correlated with BMI. Obesity was associated with increased adhesion molecules mRNA expression and protein levels in VAT, but not in SAT. Increased adhesion molecules production in visceral fat may provide a novel direct link between visceral adiposity and increased risk of cardiovascular complications., L. Bošanská ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Smoking is the most widespread substance dependence in the world. Nicotine and some other components of the cigarette smoke cause various endocrine imbalances, and have negative effects on pituitary, thyroid, adrenal, testicular and ovarian functions. Here, we examined studies that describe the influence of smoking and smoking cessation on the male and female reproductive systems. We also focused on studies providing an account of differences in cessation success rates between men and women. In men, the most common effects associated with smoking are erectile dysfunction and decreasing spermiogram quality. Several groups have studied the effects of cigarette smoking on testosterone levels in men. However, the results have been conflicting. In women, nicotine has an antiestrogen effect and increases the ratio of androgens to estrogens throughout life. Beside nicotine, other cigarette toxins also cause dysregulation of reproductive and hormonal system, and essentially influence the probability of a successful pregnancy not only in cases of assisted reproduction but also in healthy women. Tobacco addiction is one of the forms of addiction that are generally thought to be different for men and for women. Women are less successful than men in quitting smoking, and nicotine replacement therapy is less effective in female smokers. We also summarize recent studies that have indicated possible reasons., H. Jandíková, M. Dušková, L. Stárka., and Obsahuje bibliografii
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
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
Essential hypertension is a major risk factor for several cardiovascular diseases. It is a complex trait resulting from the interactions of multiple genetic and environmental factors. Moreover, not only genetic but also epigenetic inheritance plays a significant role. One can speculate that hypertension develops as a consequence of “errors” in well-coordinated regulatory systems of blood pressure. Errors in the cascade of molecular, biochemical and genetic processes, which regulate blood pressure, have finally enough potential to result in hypertension. Numerous environmental factors surrounding the organism during its development should influence the expression of genetic information. However, despite the considerable research effort, it is still difficult to identify all genes and/or other genetic determinants leading to essential hypertension and other cardiovascular diseases. This is mainly because these diseases usually become a medical problem in adulthood, although their roots might be traced back to earlier stages of ontogeny. The link between distinct developmental periods (e.g. birth and adulthood) should involve changes in gene expression involving epigenetic phenomena. The purpose of the present paper is to bring a piece of light on gene-environmental interactions potentially implicated in the pathogenesis of hypertension., J. Kuneš, J. Zicha., and Obsahuje seznam literatury
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