The aim of this study was to assess the effects of radiofrequency electromagnetic field (RF EMF) on heart rate variability (HRV) in rabbits with intensity slightly exceeding the limits for occupations. Totally 21 New Zealand white rabbits divided into two groups were used in this double-blind study. The first group of animals without general anesthesia was subjected to HRV examination under exposure to a device generated RF EMF source (frequency 1788 MHz, intensity 160 V/m, lasting 150 min.). The second group (premedications + α chloralose mg/kg) underwent the same protocol under the exposure to the real RF EMF signal from the base stations of mobile providers (frequency range 1805 - 1870 MHz - corresponding to the downlink signal of Slovak mobile providers, 160 V/m, 150 min., respectively). Individual 5-min records were used to analyze the HRV parameters: heart rate and root Mean Square of the Successive Differences (rMSSD) for time domain analysis and spectral powers in the low (LF-VFS) and high frequency (HF-VFS) bands for frequency domain analysis. Our study revealed the increased in HRV parameters (HF-HRV, rMSSD) associated with lower heart rate indicating increased cardiac vagal control under the exposure to RF EMF in experimental methods., Jakub Misek, Marcel Veterník, Ingrid Tonhajzerova, Viera Jakusova, Ladislav Janousek, Jan Jakus., and Obsahuje bibliografii
The development of neurogenic pulmonary edema (NPE) can be elicited by an immediate epidural balloon compression of the thoracic spinal cord. To evaluate whether a slower balloon inflation could prevent NPE development, we examined the extent of NPE in animals lesioned with a rapid (5 μl - 5 μl - 5 μl) or slow rate (3 μl - 2 μl - 2 μl - 2 μl - 2 μl - 2 μl - 2 μl) of balloon inflation. These groups were compared with the NPE model (immediate inflation to 15 μl) and with healthy controls. Slow balloon inflation prevented NPE development, whereas the pulmonary index and histology revealed a massive pulmonary edema in the group with a rapid rate of balloon inflation. Pulmonary edema was preceded by a considerable decrease in heart rate during the inflation procedure. Moreover, rapid inflation of balloon in spinal channel to either 5 μl or 10 μl did not cause NPE. Thus, a slow rate of balloon inflation in the thoracic epidural space prevents the development of neurogenic pulmonary edema, most likely due to the better adaptation of the organism to acute circulatory changes (rapid elevation of systemic blood pressure accompanied by profound heart rate reduction) during the longer balloon inflation period. It should be noted that spinal cord transection at the same level did not cause neurogenic pulmonary edema., J. Šedý ... [et al.]., and Obsahuje seznam literatury
In order to re-evaluate the presence and relative quantity of 2b and 2x/d myosin heavy chain (MyHC) transcripts in rat slow soleus muscle by using real time RT-PCR we have compared the available relevant cDNA sequences and designed a new set of primers having similar melting temperatures, matching separate MyHC exons in the regions of maximal differences in MyHC coding sequences, and containing G or C at the 3́-end. These also yielded PCR products of corresponding length, which is an important requirement for real time RT-PCR quantification. The experiments were performed on 8- month-old inbred female Lewis strain rats used in our current study of regenerating transplanted muscles. The real time RT-PCR measurement confirmed the expression of all four MyHC mRNAs (type 1, 2a, 2x/d and 2b) in both fast extensor digitorum longus and slow soleus muscles, although in the soleus muscle of adult rats, only type 1 and 2a protein isoforms can be usually detected, J. Žurmanová, F. Půta, R. Stopková, T. Soukup., and Obsahuje bibliografii a bibliografické odkazy
Whole cell patch-clamp recordings from GABAergic cells of thalamic reticular nucleus (RTN) in thalamocortical slices made from postnatal day 6 (P6) to 10 (P10) were used to investigate the pattern of rebound bursts (RBs) triggered by an injection of hyperpolarizing current into RTN cells. The number of RBs in the RTN and the overlying Na+/K+ spikes changed in an agedependent manner. The generation of RBs depended largely on the amplitude of the after-hyperpolarizations (AHPs). RB patterns in response to hyperpolarizing current injection into relay cells were markedly different from RB patterns in RTN cells with an after-depolarization. GABAA receptor antagonist bicuculline methiodide (BMI) changed burst firing patterns, increasing the duration of RB and decreasing the amplitude of AHP in RTN cells. Furthermore, local puffs of NMDA in the presence of BMI induced RBs. K+ channel blocker 4-aminopyridine partially mimicked the effect of BMI on AHPs. The shapes of RBs were altered by a selective CaMKII inhibitor KN-62, but not by an inactive analog KN-04., X. Wang ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Increased amount of collagen type I and decreased amount of type III is described in various pathological processes in the vascular wall. Polyphenols were shown to have protective effect on endothelium, decrease blood pressure and prevent oxidative damage induced by various stimuli. Tetrachlormethane (CCl4) is a toxic substance with known negative systemic effects induced by free radicals. Chronic administration of CCl4 for 12 weeks led to an increase of collagen type I and a decrease of type III in the wall of aorta. Parallel administration of red wine polyphenols significantly reduced the increase of collagen type I, at the same time the content of type III rose to the level above controls. After 4 weeks of spontaneous recovery no changes were observed. If polyphenols were administered during the recovery period, there was a decrease of type I and an increase of type III collagen content in the aorta. It can be concluded that polyphenols have a tendency to lower the amount of type I and to increase the proportion of type III collagen in the wall of the aorta. These changes are significant in prevention or in regression of changes induced by chronic oxidative stress. This effect of polyphenols is most likely the result of their influence on MMP-1 and TIMP activities through which they positively influence the collagen types I and III content ratio in the vascular wall in favor of the type III collagen., L. Hlavačková ... [et al.]., and Obsahuje seznam literatury
In this review, we focused on the intersection between steroid metabolomics, obstetrics and steroid neurophysiology to give a comprehensive insight into the role of sex hormones and neuroactive steroids (NAS) in the mechanism controlling pregnancy sustaining. The data in the literature including our studies show that there is a complex mechanism providing synthesis of either pregnancy sust aining or parturition provoking steroids. This mechanism includes the boosting placental synthesis of CRH with approaching parturition inducing the excessive synthesis of 3β-hydroxy-5-ene steroid sulfates serving primarily as precursors for placental synthesis of progestogens, estrogens and NAS. The distribution and changing activities of placental oxidoreductases are responsible for the activation or inactivation of the aforementioned steroids, which is compartment-specific (maternal and fetal compartments) and dependent on gestational age, with a tendency to shift the production from the pregnancy-sustaining steroids to the parturition provoking ones with an increasing gestational age. The fetal and maternal livers catabolize part of the bioactive steroids and also convert some precursors to bioactive steroids. Besides the progesterone, a variety of its 5α/β-reduced metabolites may significantly influence the maintenance of human pregnancy, provide protection against excitotoxicity following acute hypoxic stress, and might also affect the pain perception in mother and fetus. and M. Hill ... [et al.].
We examined the involvement of phosphatidylinositol 3-kinase (PI3K) and its effector protein ki nase B (Akt) in cardioprotective effects of ischemic preconditioning (PC) with particular regards to its role in the protection against ischemia-induced arrhythmias in isolated perfused rat heart. PI3K/Akt inhibitor wortmannin (100 nM) was administered 15 min prior to 30-min regional (left anterior descending coronary artery occlusion) ischemia for the study of ischemic arrhythmias in the hearts perfused at constant coronary flow or prior to 30-min global ischemia followed by 2-h reperfusion for the infarct size (IS) determination (tetrazolium staining) in the hearts perfused at constant pressure. PC procedure (one cycle of isch emia/reperfusion, 5 min each) significantly reduced the total number of ventricular premature complexes (PVC) and severity of arrhythmias (arrhythmia score; AS) over the whole period of left anterior descending coronary artery occlusion in comparison with non-PC controls (PVC 166±40; AS 1.6±0.2 vs . 550±60 and 3.2±0.2; respectively; P<0.05). In a setting of global ischemia/reperfusion, PC decreased IS (in % of the left ventricle, LV) by 73 %. Pretreatment with wortmannin modified neither arrhythmogenesis nor IS in the non-PC hearts. Bracketing of PC with wortmannin did not abolish antiarrhythmic protection (PVC 92±25; AS 1.7±0.2; P<0.05 vs . non-PC hearts). On the other hand, wortmannin increased IS/LV in the PC hearts to 24±1.2 % as compared with 9 ± 0.6 % in the untreated ones (P<0.05). In conclusion, PI3K/Akt inhibition did not affect reduced arrhythmogenesis during ischemia in the PC hearts indicating that in contrast to its positive role in the irreversible myocardial injury, PI3K/Akt activity is not required for protection induced by PC against ischemic arrhythmias in the rat heart., T. Ravingerová, J. Matejíková, D. Pancza, F. Kolář., and Obsahuje bibliografii
Micropatterned surfaces have been used as a tool for controlling the extent and strength of cell adhesion, the direction of cell growth and the spatial distribution of cells. In this study, chemically micropattern ed surfaces were prepared by successive plasma polymerization of acrylic acid (AA) and 1,7-octadiene (OD) through a mask. Rat vascular smooth muscle cells (VSMC), bovine endothelial cells (EC), porcine mesenchymal stem cells (MSC) or human skeletal muscle cells (HSKMC) were seeded on these surfaces in densities from 9,320 cells/cm2 to 31,060 cells/cm2. All cell types adhered and grew preferentially on the strip-like AA domains. Between day 1 and 7 after seeding, the percentage of cells on AA domains ranged from 84.5 to 63.3 % for VSMC, 85.3 to 73.5 % for E, 98.0 to 90.0 % for MSC, and 93.6 to 55.0 % for HSKMC. The enzyme-linked immunosorbent assay (ELISA) revealed that the concentration of alpha-actin per mg of protein was significantly higher in VSMC on AA. Similarly, immunofluorescence staining of von Willebrand factor showed more apparent Weibel-Palade bodies in EC on AA domains. MSC growing on AA had better developed beta-actin cytoskeleton, although they were less stained for hyaluronan receptor (CD44). In accordance with this, MSC on AA contained a higher concentration of beta-actin, although the concentration of CD44 was lower. HSKMC growing on AA had a better developed alpha-actin cytoskeleton. These results based on four cell types suggest that plasma polymerization is a suitable method for producing spatially defined patterned surfaces for controlled cell adhesion, proliferation and maturation., E. Filová ... [et al.]., and Obsahuje seznam literatury
Important fetal and perinatal pathologies, especially intrauterine growth restriction (IUGR), are thought to stem from placental hypoxia-induced vasoconstriction of the fetoplacental vessels, leading to placental hypoperfusion and thus fetal undernutrition. However, the effects of hypoxia on the fetoplacental vessels have been surprisingly little studied. We review here available experimental data on acute hypoxic fetoplacental vasoconstriction (HFPV) and on chronic hypoxic elevation of fetoplacental vascular resistance. The mechanism of HFPV includes hypoxic inhibition of potassium channels in the plasma membrane of fetoplacental vascular smooth muscle and consequent membrane depolarization that activates voltage gated calcium channels. This in turn causes calcium influx and contractile apparatus activation. The mechanism of chronic hypoxic elevation of fetoplacental vascular resistance is virtually unknown except of signs of the involvement of morphological remodeling., V. Hampl, V. Jakoubek., and Obsahuje seznam literatury
Using non-cholesterol sterols investigation several authors postulated a hypothesis that in the metabolic syndrome cholesterol endogenous synthesis is increased and its absorption decreased. Our study is the first attempt to evaluate the direct relation of cholesterol metabolism to the principal pathogenetic phenomenon of the metabolic syndrome – namely to insulin resistance. We have measured insulin sensitivity by two methods – Quicki (Quantitative Sensitivity Check Index) and intravenous insulin tolerance test (Kitt) and 3 indirect markers - fasting insulin level, fasting C-peptide level and SHBG (sex hormone binding globulin). The investigation was performed in three groups of subjects with a different prevalence of insulin resistance: 72 non-diabetics with ischemic heart disease, 117 young blood donors and 63 type 2 diabetics on diet therapy only. Analyzing altogether 60 relationships – between four sterols (lathosterol, squalene, sitosterol and campesterol) and five markers of insulin resistance in three groups of subjects – we have found only six significant relations between cholesterol synthesis and absorption and insulin resistance in all groups of patients. Our results indicate that there exists a significant relationship between insulin sensitivity and indices of either increased cholesterol synthesis or decreased cholesterol absorption. Insulin resistance explains only a part of both abnormalities mentioned above., A. Šmahelová, R. Hypšler, T. Haas., and Obsahuje bibliografii a bibliografické odkazy