The 24-hour periodicity of supraventricular (SVPB) and ventricular (VEB) extrasystoles in healthy elderly men (age 49-69 years) was studied at two altitudes during 24 h Holter ECG monitoring. At the low altitude (200 m, n = 26), SVPB were more frequent than VEB. The highest occurrence of SVPB was at 17:00 h, the lowest at 01:00 and 02:00 h (P<0.001). The highest occurrence of VEB was at 09:00 h, the lowest one at 04:00 h (P<0.001). At 1350 m (n=9) the incidence of both SVPB and VEB was approximately twofold higher compared to that at the low altitude (P<0.001). The highest occurrence of SVPB was at 13:00 h, the lowest at 06:00 h (P<0.001). VEB were the most frequent at 10:00 h and 13:00 h, while the lowest frequency was observed at 06:00 h (P<0.001). Our results indicate that the incidence of SVPB and VEB in healthy persons at the moderate altitude is twofold and its periodicity is shifted compared to the low altitude. The cause of increased occurrence of extrasystoles is probably due to β-adrenergic activation of the heart at the higher altitude., Š. Kujaník, M. Sninčák, J.Vokáľ, J. Podracký, J. Koval., and Obsahuje bibliografii
Resistance to steroid hormones presents a serious problem with respect to their mass use in therapy. It may be caused genetically by mutation of genes involved in hormonal signaling, not only steroid receptors, but also other players in the signaling cascade as co-regulators and other nuclear factors, mediating the hormone-born signal. Another possibility is acquired resistance which may develop under long-term steroid treatment, of which a particular case is down regulation of the receptors. In the review recent knowledge is summarized on the mechanism of main steroid hormone action, pointing to already proven or potential sites causing steroid resistance. We have attempted to address following questions: 1) What does stay behind differences among patients as to their response to the (anti)steroid treatment? 2) Why do various tissues/cells respond differently to the same steroid hormone though they contain the same receptors? 3) Are such differences genetically dependent? The main attention was devoted to glucocorticoids as the most frequently used steroid therapeutics. Further, androgen insensitivity is discussed with a particular attention to acquired resistance to androgen deprivation therapy of prostate cancer. Finally the potential causes are outlined of breast and related cancer(s) resistance to antiestrogen therapy., R. Hampl, K. Vondra., and Obsahuje bibliografii
Extensive osteolysis adjacent to orthopedic implants is often associated with wear particles of prosthetic material. The activation of the RANKL/RANK/OPG system is considered to be a likely cause of periprosthetic osteolysis leading to implant failure. The aim of this study was to examine the possible correlation between the clinical extent of osteolysis, the number of wear particles and expression of the osteoclastic mediator RANKL (receptor activator of nuclear factor kappa B ligand) in the tissues aro und aseptically loosened cemented and non-cemented total hip replacements. Periprosthetic tissues were harvested from 59 patients undergoing revision of hip replacement for aseptic loosening. We observed RANKL-positive cells in 23 of our 59 patients, their presence was noted predominantly in tissues with a loosened cemented endoprosthesis. We have found that RANKL is present only in tissues with a large amount of wear debris and predominantly in cases involving loosened cemented implants., D. Veigl, J. Niederlová, O. Kryštůfková., and Obsahuje bibliografii a bibliografické odkazy
The purpose of this study was to investigate plasma concentrations of cyclic guanosine monophosphate (cGMP) and atrial natriuretic peptide (ANP) during and after real and simulated space flight. Venous blood was obtained 3 min after the beginning and 2 min after the lower body negative pressure maneuver in two cosmonauts preflight (supine), inflight, and postflight (supine) and in five other subjects before, at the end, and 4 days after a 5-day head-down tilt (-6°) bed rest. In cosmonaut 1 (10 days in space), plasma cGMP fell from preflight 4.3 to 1.4 nM on flight day 6, and was 3.0 nM on the fourth day after landing. In cosmonaut 2 (438 days in space), it fell from preflight 4.9 to 0.5 nM on on flight day 3, and stayed <0.1 nM with 5, 9, and 14 months in space, as well as on the fourth day after landing. Three months after the flight his plasma cGMP was back to normal (6.3 nM). Cosmonaut 2 also displayed relatively low inflight ANP values but returned to preflight level immediately after landing. In a ground-based simulation on five other persons, supine plasma cGMP was reduced by an average of 30 % within 5 days of 6° head-down tilt bed rest. The data consistently demonstrate lowered plasma cGMP with real and simulated weightlessness, and a complete disappearance of cGMP from plasma during, and shortly after long-duration space flight., A. Rössler, V. Noskov, Z. László, V.V. Polyakow, H. G. Hinghofer-Szalkay., and Obsahuje bibliografii
Diabetes mellitus is relatively frequently associated with fatty liver disease. Increased oxidative stress probably plays an important role in the development of this hepatopathy. One of possible sources of reactive oxygen species in liver is peroxisomal system. There are several reports about changes of peroxisomal enzymes in experimental diabetes, mainly enzymes of fatty acid oxidation. The aim of our study was to investigate the possible changes of activities of liver peroxisomal enzymes, other than enzymes of beta-oxidation, in experimental diabetes mellitus type 2. Biochemical changes in liver of experimental animals suggest the presence of liver steatosis. The changes of serum parameters in experimental group are similar to changes in serum of patients with non-alcoholic fatty liver disease. We have shown that diabetes mellitus influenced peroxisomal enzymes by the different way. Despite of well-known induction of peroxisomal beta-oxidation, the activities of catalase, aminoacid oxidase and NADH-cytochrome b5 reductase were not significantly changed and the activities of glycolate oxidase and NADP-isocitrate dehydrogenase were significantly decreased. The effect of diabetes on liver peroxisomes is probably due to the increased supply of fatty acids to liver in diabetic state and also due to increased oxidative stress. The changes of metabolic activity of peroxisomal compartment may participate on the development of diabetic hepatopathy., L. Turecký, V. Kupčová, E. Uhlíková, V. Mojto., and Obsahuje bibliografii
Pharmacokinetics of leptin in mammals has received limited attention and only one study has examined more than two time points and this was in ob/ob mice. This study is the first to observe the distribution of leptin over a time course in female mice. A physiologic dose (12 ng) of radiolabelled leptin was injected in adult female mice via the lateral tail vein and tissues were dissected out and measured for radioactivity over a time course up to two hours. Major targets for administered leptin included the liver, kidneys, gastrointestinal tract and the skin while the lungs had high concentrations of administered leptin per gram of tissue. Leptin was also found to enter the lumen of the digestive tract intact from the plasma. Very little of the dose (<1 %) was recovered from the brain at any time. Consequently we confirm that the brain is not a major target for leptin from the periphery, although it may be very sensitive to leptin that does get to the hypothalamus. Several of the major targets (GI tract, skin and lungs) for leptin form the interface for the body with the environment, and given the ability of leptin to modulate immune function, this may represent a priming effect for tissues to respond to damage and infection., R. A. Hart, R. C. Dobos, L. L. Agnew, R. L. Tellam, J. R. McFarlane., and Obsahuje bibliografii
Phosphorylation of phospholemman (PLM) on ser68 has been proposed to at least partially mediate cyclic AMP (cAMP) mediated relaxation of arterial smooth muscle. We evaluated the time course of the phosphorylation of phospholemman (PLM) on ser68, myosin regulatory light chains (MRLC) on ser19, and heat shock protein 20 (HSP20) on ser16 during a transient forskolin-induced relaxation of histamine-stimulated swine carotid artery. We also evaluated the dose response for forskolin- and nitroglycerin-induced relaxation in phenylephrine-stimulated PLM-/- and PLM+/+ mice. The time course for changes in ser19 MRLC dephosphorylation and ser16 HSP20 phosphorylation was appropriate to explain the forskolin-induced relaxation and the recontraction observed upon washout of forskolin. However, the time course for changes in ser68 PLM phosphorylation was too slow to explain forskolin-induced changes in force. There was no difference in the phenylephrine contractile dose response or in forskolin-induced relaxation dose response observed in PLM-/- and PLM+/+ aortae. In aortae precontracted with phenylephrine, nitroglycerin induced a slightly, but significantly greater relaxation in PLM-/- compared to PLM+/+ aortae. These data are consistent with the hypothesis that ser19 MRLC dephosphorylation and ser16 HSP20 phosphorylation are involved in forskolin-induced relaxation. Our data sugge st that PLM phosphorylation is not significantly involved in forskolin-induced arterial relaxation., M. K. Meeks, S. Han, A, L. Tucker, C. M. Rembold., and Obsahuje bibliografii a bibliografické odkazy
Whole-body vibration (WBV) is a new exercise method, with good acceptance among sedentary subjects. The metabolic response to WBV has not been well documented. Three groups of male subjects, inactive (SED), endurance (END) and strength trained (SPRINT) underwent a session of side-alternating WBV composed of three 3-min exercises (isometric half-squat, dynamic squat, dynamic squat with added load), and repeated at three frequencies (20, 26 and 32 Hz). VO2, heart rate and Borg scale were monitored. Twenty-seven healthy young subjects (10 SED, 8 SPRINT and 9 END) were included. When expressed in % of their maximal value recorded in a treadmill test, both the peak oxygen consumption (VO2) and heart rate (HR) attained during WBV were greatest in the SED, compared to the other two groups (VO2: 59.3 % in SED vs 50.8 % in SPRINT and 48.0 % in END, p<0.01; HR 82.7 % in SED vs 80.4 % in SPRINT and 72.4 % in END, p<0.05). In conclusions, the heart rate and metabolic response to WBV differs according to fitness level and type, exercise type and vibration frequency. In SED, WBV can elicit sufficient cardiovascular response to benefit overall fitness and thus be a potentially useful modality for the reduction of cardiovascular risk., B. Gojanovic, F. Feihl, G. Gremion, B. Waeber., and Obsahuje bibliografii
Fibroblast growth factor (FGF) signaling plays an important role during embryonic induction and patterning, as well as in modulating proliferative and hypertrophic growth in fetal and adult organs. Hemodynamically induced stretching is a powerful physiological stimulus for embryonic myocyte proliferation. The aim of this study was to assess the effect of FGF2 signaling on growth and vascularization of chick embryonic ventricular wall and its involvement in transmission of mechanical stretchinduced signaling to myocyte growth in vivo . Myocyte proliferation was significantly higher at the 48 h sampling interval in pressure-overloaded hearts. Neither Western blotting, nor immunohistochemistry performed on serial paraffin sections revealed any changes in the amount of myocardial FGF2 at that time point. ELISA showed a significant increase of FGF2 in the serum. Increased amount of FGF2 mRNA in the heart was confirmed by real time PCR. Blocking of FGF signaling by SU5402 led to decreased myocyte proliferation, hemorrhages in the areas of developing vasculature in epicardium and digit tips. FGF2 synthesis is increased in embryonic ventricular cardiomyocytes in response to increased stretch due to pressure overload. Inhibition of FGF signaling impacts also vasculogenesis, pointing to partial functional redundancy in paracrine control of cell proliferation in the developing heart., E. Krejci, Z. Pesevski, O. Nanka, D. Sedmera., and Obsahuje bibliografii