Rhythmic daily changes in the Na,K-ATPase activity have been previously described for rat kidney cortex, showing two peaks: at 0900 h and 2100 h, and two valleys: at 1500 h and 0100 h - 0300 h. The oscillations in Na,K-ATPase activity are produced by an inhibitor, which binds the enzyme and is present in the rat blood plasma at valley times and absent or at very low concentrations at peak times. Since it has been demonstrated that active Na+ extrusion from the cells of several tissues depends not only on the Na,K-ATPase but also on the ouabain-insensitive Na-ATPase, we studied the activity of this latter enzyme of several rat tissues, i.e., kidney cortex, small intestine, liver, heart and red blood cells along the day. None of these tissues showed any variation of their Na-ATPase activity along the day. Preincubation of kidney cortex homogenates obtained at 0900 h, with blood plasma drawn at 0900 h and 1500 h, did not modify the Na-ATPase activity. Our results indicate that the Na-ATPase activity does not oscillate along the day. These results are in agreement with the idea that the Na-ATPase could partially compensate the Na+ transport affected by oscillations of the Na,K-ATPase activity., A. Reyes ... [et al.]., and Obsahuje seznam literatury
Functional C(-260)→T polymorphism in the promoter of the CD14 gene has been reported to be associated with coronary heart disease (CHD). The functional role of the polymorphism, however, is still a matter of debate, since several studies have not proved its effect on clinical outcomes associated with atherosclerosis. Cardiovascular-related morbidity and mortality was assessed in a post-hoc approach four years after baseline characterization of patients (male/female n = 36/32) with angiographically proven coronary heart disease. CD14 C(-260)→T promoter genotype was determined at baseline. Seventeen out of 20 CHD patients with non-lethal cardiovascular events carried at least one T-allele. CD14 T-260 allele carriers have a 3.59-fold (95 % confidence interval: 1.11-6.75) increased risk for non-lethal cardiovascular events (Kaplan-Meier plot: log rank test p = 0. 029). All patients with lethal outcomes (n = 6) were also T-allele carriers. Multivariate logistic regression analysis among CHD patients including age, established risk factors and the C(-260)→T polymorphism as covariates and non-lethal events as a dependent variable confirmed the independent prospective effect of the T-allele on cardiovascular outcomes in this subset. Further evidence is provided for the role of CD14 C(-260)→T promoter polymorphism as a genetic susceptibility marker of atherosclerosis in patients with an advanced clinical course of the disease. Due to the small sample size and post-hoc character of the study large-scale prospective studies that monitor patients with proven CHD are needed to confirm these findings., M. Porsch-Öucürümez, J.Hucke, S. Westphal, J. A. Hubáček, G. Schmitz, C. Luley., and Obsahuje bibliografii a bibliografické odkazy
Metabolic consequences of direct muscle trauma are insufficiently defined. Their effects on the ubiquitin-proteasome pathway (UPP) of protein degradation in human skeletal muscles are as yet unknown. Thus, we investigated whether the UPP is involved in the metabolic response evoked in directly traumatized human skeletal muscles. Biopsies were obtained from contused muscles after fractures and from normal muscles during elective implant removal (control). As estimated by western blot analyses, concentrations of free ubiquitin and ubiquitin protein conjugates were similar in extracts from injured and uninjured muscles. Ubiquitin protein ligation rates were reduced after injury (1.5±0.2 vs. 1.0±0.15 fkat/μg; p=0.04). Chymotryptic-, tryptic- and caspase-like proteasome peptidase activities (total activity minus activity in the presence of proteasome inhibitors) increased significantly after trauma (p=0.04 - 0.001). Significant increases in total chymotryptic- and caspase-like activities were attributable to proteasome activation. Our results extend the possible role of the UPP in muscle wasting to direct muscle trauma. They further suggest that the effects of direct mechanical trauma are not limited to the proteasome and imply that ubiquitin protein ligase systems are also involved. Based on the potential role of the UPP in systemic diseases, it might also be a therapeutic target to influence muscle loss in critically ill blunt trauma patients, in which large proportions of muscle are exposed to direct trauma. and Obsahuje bibliografii a bibliografické odkazy
Central administration of losartan effectively blocked the increase of blood pressure and drinking response induced by angiotensin II (Ang II) or carbachol. However, the relationship between angiotensin AT1 receptors and the natriuresis induced by brain cholinergic stimuli is still not clear. The purpose of the study is to reveal the role of brain angiotensin AT1 receptor in the carbachol-induced natriuresis and expression of neuronal nitric oxide synthase (nNOS) in the locus coeruleus (LC) and proximal co nvoluted tubule (PCT). Our results indicated that 40 min after in tracerebroventricular (ICV) injection of carbachol (0.5 μg), urinary sodium excretion was significantly increased to 0.548±0.049 μmol·min-1·100 g-1. Immunohistochemistry showed that carbachol induced an increase of neuronal nitric oxide synthase immunoreactivity (nNOS-IR) in the LC and renal proximal tubular cells. After pretreatment with losartan (20 μg), carbachol-induced urinary sodium excretion was reduced to 0.249±0.067 μmol·min-1·100 g-1. The same was true for carbachol-induced increase of nNOS-IR in the LC and PCT. The present data suggest that ICV cholinergic stimulation could induce a natriuresis and upregulate the activity of nNOS in the LC and PCT. The blockade of AT1 receptors might downregulate the effects induced by carbachol in the LC and PCT. Consequently, we provide a new evidence that brain angiotensinergic pathway and NO-dependent neural pathway contribute to the natriuresis following brain cholinergic stimulation and thus play an important role in the regulation of fluid homeostasis. Furthermore, the final effect of nitric oxide on proximal tubular sodium reabsorption participated in the natriuresis induced by brain cholinergic stimulation., M. Wang, C. L. Jiang, C. Y. Wang, Q. Y. Yao., and Obsahuje bibliografii a bibliografické odkazy
We present a review about the relationship between ryanodine receptors and voltage-gated calcium channels in myocardium, and also how both of them are related to protein kinase A. Ryanodine receptors, which have three subtypes (RyR1-3), are located on the membrane of sarcoplasmic reticulum. Different subtypes of voltage-gated calcium channels interact with ryanodine receptors in skeletal and cardiac muscle tissue. The mechanism of excitation-contraction coupling is therefore different in the skeletal and cardiac muscle. However, in both tissues ryanodine receptors and voltage-gated calcium channels seem to be physically connected. FK-506 binding proteins (FKBPs) are bound to ryanodine receptors, thus allowing their concerted activity, called coupled gating. The activity of both ryanodine receptors and voltage-gated calcium channels is positively regulated by protein kinase A. These effects are, therefore, components of the mechanism of sympathetic stimulation of myocytes. The specificity of this enzyme’s targeting is achieved by using different A kinase adapting proteins. Different diseases are related to inborn or acquired changes in ryanodine receptor activity in cardiac myocytes. Mutations in the cardiac ryanodine receptor gene can cause catecholamine-provoked ventricular tachycardia. Changes in phosphorylation state of ryanodine receptors can provide a credible explanation for the development of heart failure. The restoration of their normal level of phosphorylation could explain the positive effect of beta-blockers in the treatment of this disease. In conclusion, molecular interactions of ryanodine receptors and voltage-gated calcium channels with PKA have a significant physiological role. However, their defects and alterations can result in serious disturbances., M. M. Petrovič, K. Valeš, B. Putnikovič, V. Djulejič, D. M. Mitrovič., and Obsahuje bibliografii a bibliografické odkazy
Serum adipocyte fatty acid-binding protein (FABP) concentrations are linked to human obesity and other features of metabolic syndrome. Whether FABP associates with metabolic alterations in chronic malnutrition is unknown. In the present study, we measured fasting serum levels of FABP, leptin, soluble leptin receptor, adiponectin, resistin, C-reactive protein (CRP), insulin, glucose, cholesterol and triglycerides in 19 patients with a restrictive type of anorexia nervosa (AN) and in 16 healthy age-matched control women (C). Body mass index, serum leptin, and CRP concentrations were significantly lower, while serum adiponectin and soluble leptin receptor levels were significantly higher in AN relative to C group. Serum insulin, glucose, cholesterol and triglyceride levels did not differ between the groups studied. Serum FABP leve ls were unchanged in patients with AN and were not related to any of parameters studied. We conclude that, in contrast to patients with obesity where FAPB is a prominent marker of metabolic alterations, chronic malnutrition in AN does not significantly affect its serum levels., D. Haluzíková ... [et al.]., and Obsahuje seznam literatury
Ghrelin is a gut peptide produced mainly by stomach, well known to induce appetite stimulatory actions. Obestatin, a recently identified peptide derived from preproghrelin, was initially described to antagonize stimulatory effect of ghrelin on food intake. The postprandial response of obestatin and its relationship with ghrelin in humans remains unknown. We therefore investigated the postprandial response of obestatin and total ghrelin, acyl and desacyl ghrelin and neuropeptide Y (NPY) to a high-carbohydrate breakfast (1 604 kJ) in eight healthy women (age: 24.2±0.82 years; BMI 21.6±0.61 kg/m2). Blood samples were collected before the meal, and 30, 60, 90, 120 and 150 min after the breakfast consumption. Postprandial plasma obestatin concentrations significantly decreased compared with preprandial levels as well as total ghrelin concentrations and reached the lowest values 90 and 120 min after the meal consumption, respectively (p 0.05). Plasma acyl and desacyl ghrelin concentrations decreased after the breakfast and reached lowest values in 30 and 60 min, respectively (p<0.05). Plasma NPY concentrations were lower than preprandial levels 90 and 150 min after consuming breakfast (p<0.05). In conclusion, we demonstrated in healthy young women that plasma obestatin concentrations decrease similarly to ghrelin after a high-carbohydrate breakfast., D. Sedláčková, I. Dostálová, V. Hainer, L. Beranová, H. Kvasničková, M. Hill, M. Haluzík, J. Nedvídková., and Obsahuje bibliografii a bibliografické odkazy
The mitochondrial DNA (mtDNA) amount in cells as the basis for mitochondrial energy generating system, which produces ATP, plays an important role in the fetal development and postnatal morbidity. Isolated human cord blood leukocytes (HCBL) contribute very little to the overall metabolic turnover, but they may serve as easily available marker cells for the study of the mtDNA amount changes in cord blood during fetal development. The aim of our study was to analyze the mtDNA amount in HCBL. HCBL were isolated from cord blood samples of 107 neonates born between the 25th and 41st week of gestation. The mtDNA amount was analyzed by the real-time PCR method. The significant negative correlations were found between the relative mtDNA amount in HCBL and gestational age (r = -0.54, p<0.01) and birth weight (r = -0.43, p<0.01), respectively. The results revealed that the mtDNA content per cell decreases in HCBL with progressing fetal development. This may be explained by gradual shift of the hematopoiesis from fetal liver to bone marrow during the second half of pregnancy presumably accompanied by decreasing cell volume of HCBL as it was shown similarly in red blood cells., M. Pejznochová, M. Tesařová, T. Honzík, H. Hansíková, M. Magner, J. Zeman., and Obsahuje bibliografii a bibliografické odkazy
Molecular modeling of the H4-H5-loop of the α2 isoform of Na+/K+-ATPase in the E1 and E2 conformations revealed that twisting of the nucleotide (N) domain toward the phosphorylation (P) domain is connected with the formation of a short π-helix between Asp369 and Thr375. This conformational change close to the hinge region between the N-domain and the P-domain could be an important event leading to a bending of the N-domain by 64.7° and to a shortening of the distance between the ATP binding site and the phosphorylation site (Asp369) by 1.22 nm from 3.22 nm to 2.00 nm. It is hypothesized that this shortening mechanism is involved in the Na+-dependent formation of the Asp369 phospho-intermediate as part of the overall Na+/K+-ATPase activity., G. Tejral ... [et al.]., and Obsahuje seznam literatury
Medical genetic research achieved in last decade many efforts leading to better understanding of inherited basis of human diseases. This will not be possible without the participation of patients and controls. However, the general understanding of the background and possibilities of genetic association studies is very low. It was confirmed by study of university of students. Because of the fair of misuses of the individual genetic information, significant part of participants refused the use of already donated blood samples for genetic testing but agreed with using of buccal swabs for the same analysis. To enhance the general knowledge’s of the population, leading to realistic expectations not just about genetic predictive power but also about the eventual risks in behind will be the major mission in the next years., V. Adámková ... [et al.]., and Obsahuje seznam literatury