During vertebrate evolution, structural changes in red blood cells (RBC) and hemoglobin (Hb), have probably resulted in the importance of blood carbon dioxide transport. The chloride/bicarbonate exchange across the RBC membrane, which is an integral part of the blood CO2 transport process in vertebrates, has been examined on two different species of teleost fish, Euthynnus alletteratus and Thunnus thynnus, at several oxygenation states of erythrocyte HOS (high-oxygenation state, about 90 % of saturation) and LOS (low-oxygenation state, about 15 % of saturation). The results were compared with those observed in human RBC under the same experimental conditions and with the chicken (Gallus gallus) erythrocytes, which have particular modifications at the N-terminus of the band 3 protein (B3). In fish the kinetic measurements have shown a different anion transport in several oxygenation states of erythrocytes, indicating that also at lower levels of vertebrate evolution there exists a modulation of the anionic flow affected by oxygen. The functional correlation of anion transport to changes of parts of the hemoglobin sequence responsible for alterations in the interactions with the cytoplasmic domain of band 3 protein (cdb3) allowed us to suggest a hypothesis about fish physiology. The highest values of kinetic measurements observed in fish have been attributed to the metabolic need of the RBC in response to the removal of CO2 that in teleosts is also of endogenous origin., A. Russo, E. Tellone, S. Ficarra, B. Giardina, E. Bellocco, G. Lagana, U. Leuzzi, A. Kotyk, A. Galtieri., and Obsahuje bibliografii a bibliografické odkazy
1a_It has been known for many years that baroreflex sensitivity is lowered in hypertensive patients. There are several known factors implicating this association, e.g. high blood pressure leads to remodeling of the carotid arterial wall, to its stiffness and to a diminished activation of baroreceptors; leptin released from a fatty tissue activates the sympathetic nervous system etc. On the other hand, low baroreflex sensitivity (BRS, usually quantified in ms/mmHg) can be inborn. Studies on primary hypertension in children and adolescents have brought new information about the role of baroreflex in the development of an early stage of primary hypertension. BRS lower than 3.9 ms/mmHg was found in 5 % of healthy subjects. This value approaches the critical value for the risk of sudden cardiac death in patients after myocardial infarction and corresponds to the value present in hypertensive patients. A decreased BRS and BRSf (baroreflex sensitivity expressed in mHz/mmHg, index independent of the mean cardiac interval), was found not only in children with hypertension, but also in those with white-coat hypertension. This is in accordance with a single interpretation. The decrease of BRS/BRSf precedes a pathological blood pressure increase., 2a_The contribution of obesity and BRS/BRSf to the development of hypertension in adolescents was also compared. Both factors reach a sensitivity and a specificity between 60 % and 65 %, but there is no correlation between the values of the body mass index and BRS either in the group of hypertensive patients or in healthy controls. If a receiver operating curve (sensitivity versus specificity) is plotted for both values together using logistic regression analysis, a sensitivity higher than 70 % and a specificity over 80 % are reached. This means that low baroreflex sensitivity is an independent risk factor for the development of primary hypertension. Studies demonstrate that adolescents with increased blood pressure and with BRS under 7 ms/mmHg should be given care and intensively motivated to change their lifestyle including a change in diet and increase in physical activity., and N. Honzíková, B. Fišer.
In this study, we focused on an analysis of biguanides effects on mitochondrial enzyme activities, mitochondrial membrane potential and membrane permeabili ty transition pore function. We used phenformin, which is more efficient than metformin, and evaluated its effect on rat liver mitochondria and isolated hepatocytes. In contrast to prev iously published data, we found that phenformin, after a 5 min pr e-incubation, dose-dependently inhibits not only mitochondrial complex I but also complex II and IV activity in isolated mitochondria. The enzymes complexes inhibition is paralleled by the decreased respiratory control index and mitochondrial membrane potent ial. Direct measurements of mitochondrial swelling revealed that phenformin increases the resistance of the permeability transition pore to Ca 2+ ions. Our data might be in agreement with the hypothesis of Schäfer (1976) that binding of biguanides to membrane phospholipids alters membrane properties in a non-specific manner and, subsequently, different enzyme activities are modified via lipid phase. However, our measurements of anisotropy of fluorescence of hydrophobic membrane probe diphenylhexatriene have not shown a measurable effect of membrane fluidity with the 1 mM concentration of phenformin that strongly inhibited complex I activity. Our data therefore suggest that biguanides could be considered as agents with high efficacy but low specifity., Z. Drahota ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
A new generator of two successive shock waves focused to a common focal point has been developed. Cylindrical pressure waves created by multichannel electrical discharges on two cylindrical composite anodes are focused by a metallic parabolic reflector - cathode, and near the focus they are transformed to strong shock waves. Schlieren photos of the focal region have demonstrated that mutual interaction of the two waves results in generation of a large number of secondary short-wavelength shocks. Interaction of the focused shockwaves with liver tissues and cancer cell suspensions was investigated. Localized injury of rabbit liver induced by the shock waves was demonstrated by magnetic resonance imaging. Histological analysis of liver samples taken from the injured region revealed that the transition between the injured and the healthy tissues is sharp. Suspension of melanoma B16 cells was exposed and the number of the surviving cells rapidly decreased with increasing number of shocks and only 8 % of cells survived 350 shocks. Photographs of cells demonstrate that even small number of shocks results in perforation of cell membranes., J. Beneš, P. Šunka, J. Králová, J. Kašpar, P. Poučková., and Obsahuje bibliografii
The production of the pineal hormone melatonin is synchronized with day-night cycle via multisynaptic pathway including suprachiasmatic nucleus linking several physiological functions to diurnal cycle. The recent data indicate that impaired melatonin production is involved in several cardiovascular pathologies including hypertension and ischemic heart disease. However, the mechanisms of melatonin effect on cardiovascular system are still not completely understood. The activation of melatonin receptors on endothelial and vascular smooth muscle cells and antioxidant properties of melatonin could be responsible for the melatonin effects on vascular tone. However, the data from in vitro studies are controversial making the explanation of the melatonin effect on blood pressure in vivo difficult. In vivo, melatonin also attenuates sympathetic tone by direct activation of melatonin receptors, scavenging free radicals or increasing NO availability in the central nervous system. The central and peripheral antiadrenergic action of chronic melatonin treatment might eliminate the mechanisms counter-regulating decreased blood pressure, providing thus additional cardioprotective mechanism. The extraordinary antioxidant activity and antilipidemic effects of melatonin may enhance the modulation of blood pressure by melatonin and probably play the most important role in the amelioration of target organ damage by chronic melatonin treatment. Further investigation of these mechanisms should provide novel knowledge about pathophysiological mechanisms of cardiovascular diseases, additional explanation for their circadian and seasonal variability and potentially generate new impulses for the development of therapeutic arsenal., Ľ. Paulis, F. Šimko., and Obsahuje bibliografii a bibliografické odkazy
Sympathetic activation and parasympathetic withdrawal are commonly observed during acute exacerbations of chronic obstructive pulmonary disease (COPD). We have demonstrated previously that noninvasive positive-pressure ventilation (NPPV) improves parasympathetic neural control of heart rate in patients with obstructive sleep apnea. We hypothesized that NPPV may exert such beneficial effects in COPD as well. Therefore, we assessed the acute effects of NPPV on systemic blood pressure and indexes of heart rate variability (HRV) in 23 patients with acute exacerbations of COPD. The measurements of HRV in the frequency domain were computed by an autoregressive spectral technique. The use of NPPV resulted in significant increases of oxygen saturation (from 89.2±1.0 to 92.4±0.9 %, p<0.001) in association with reductions in systolic and diastolic blood pressures and heart rate (from 147±3 to 138±3 mm Hg, from 86±2 to 81±2 mm Hg, from 85±3 to 75±2 bpm, p<0.001 for all variables), and increases in ln-transformed high frequency band of HRV (from 6.4±0.5 to 7.4±0.6 ms2/Hz, p<0.01). Reductions in heart rate and increases in ln-transformed HF band persisted after NP PV withdrawal. In conclusion, these findings suggest that NPPV may cause improvements in the neural control of heart rate in patients with acute exacerbations of COPD., P. Skyba, P. Joppa, M. Orolín, R. Tkáčová., and Obsahuje bibliografii a bibliografické odkazy
The gold standard material in bypass surgery of blood vessels remains the patient’s own artery or vein. However, this material may be unavailable, or may suffer vein graft disease. Currently available vascular prostheses, namely polyethylene terephthalate (PET, Dacron) and expanded poly tetrafluoroethylene (ePTFE), perform well as large-caliber replacements, but their long-term patency is discouraging in small-caliber applications (<6 mm), such as in coronary, crural or microvessel surgery. This failure is mainly a result of an unfavorable healing process with surface thrombogenicity, due to lack of endothelial cells and anastomotic intimal hyperplasia caused by hemodynamic disturbances. An ideal small-diameter vascular graft has become a major focus of research. Novel biomaterials have been manufactured, and tissue-biomaterial interactions have been optimized. Tissue engineering technology has proven that the concept of partially or totally living blood vessels is feasible. The purpose of this review is to outline the vascular graft materials that are currently being implanted, taking into account cell-biomaterial physiology, tissue engineering approaches and the collective achievements of the authors., J. Chlupáč, E. Filová, L. Bačáková., and Obsahuje seznam literatury
In the present paper we describe changes of anatomical parameters in inbred Lewis strain rats, namely their body weight, body weight gain per week, absolute and relative heart, thyroid gland and skeletal muscle weights, that are assumed to reflect experimentally altered thyroid status. The hyperthyroid state was induced by DL-thyroxine or Na 3,3',5-triiodo-L-thyronine, while methimazole was employed for inducing hypothyroidism. We have found that when compared to euthyroid rats, hypothyroidism resulted in a significantly lower body weight gain, absolute and relative heart weight and, in contrast, in a significant increase of absolute and relative thyroid gland weight. On the other hand, hyperthyroidism led to a significant increase of absolute and relative heart weight and to a significant reduction of absolute and relative thyroid gland weight. However, the body mass was not significantly altered in hyperthyroidism as compared with euthyroid rats. We conclude that our protocol leads to chronic hyper- or hypothyroidism as demonstrated by body, heart and thyroid gland weight changes. These anatomical data can thus be utilized as supplemental criteria for the assessment of the thyroid state of experimental rats., T. Soukup, G. Zachařová, V. Smerdu, I. Jirmanová., and Obsahuje bibliografii
We investigated the renal response to direct renal nerve stimulation, 2 weeks following reversal of 24-h unilateral (left) ureteric obstruction. Renal nerve stimulation caused a 13-15 % fall in renal blood flow, in 4 groups of anesthetized rats following ureteric obstruction (n=9) or a sham operation (n=7) both with (n=9) and without (n=7) treatment with the mixed ETA/B receptor antagonist, bosentan. In the sham-operated rats, renal nerve stimulation did not change glomerular filtration rate but reduced urine flow rate (37±3 %, P<0.001), and absolute (38±4 %, P<0.001) and fractional (35±5 %, P<0.01) sodium excretion. Following unilateral ureteric obstruction, renal nerve stimulation increased glomerular filtration rate by 22±3 % (P<0.01), but reduced urine flow rate (14±2 %, P<0.001) and fractional sodium excretion (23±5 %, P<0.01). Bosentan treatment had no effect on baseline or renal responses to renal nerve stimulation in the sham group but normalized the renal response to renal nerve stimulation in the unilateral ureteric obstruction group. We conclude that 14 days after a 24-h period of unilateral ureteric obstruction there is an increase in GFR in response to direct renal nerve stimulation, which is due, in part, to the actions of endothelin at the time of obstruction., F. T. Hammad, A. M. Wheatley, G. Davis., and Obsahuje bibliografii
Colonic mucosal protection is provided by the mucus gel, mainly composed of mucins. Several factors can modulate the formation and the secretion of mucins, and among them butyrate, an end-product of carbohydrate fermen tation. However, the specific effect of butyrate on the various colonic mucins, and the consequences in terms of the mucus layer thickness are not known. Our aim was to determine whether butyrate modulates colonic MUC genes expression in vivo and whether this results in changes in mucus synthesis and mucus layer thickness. Mice received daily for 7 days rectal enemas of butyrate (100 mM) versus saline. We demonstrated that butyrate stimulated the gene expression of both secreted (Muc2) and membrane-linked (Muc1, Muc3, Muc4) mucins. Butyrate especially induced a 6-fold increase in Muc2 gene expression in proximal colon. However, butyrate enemas did not modify the number of epithelial cells containing the protein Muc2, and caused a 2-fold decrease in the thickness of adherent mucus layer. Further studies should help understanding whether this last phenomenon, i.e. the decrease in adherent mucus gel thickness, results in a diminished protective function or not., E. Gaudier ... [et al.]., and Obsahuje seznam literatury