We have investigated slow inactivation in a rat axonal K+ channel, the I channel. Using voltage steps to potentials between -70 mV and +80 mV, from a holding potential of -100 mV, we observed a marked slowing of inactivation at positive potentials: the time constant was 4.5±0.4 s at -40 mV (mean ± S.E.M.), increasing to 14.7±2.0 s at +40 mV. Slowed inactivation at positive potentials is not consistent with published descriptions of C-type inactivation, but can be explained by models in which inactivation is preferentially from closed states (which have been developed for Kv2.1 and some Ca2+ channels). We tested two predictions of preferential closed-state models: inactivation should be more rapid during a train of brief pulses than during a long pulse to the same potential, and the cumulative inactivation measured with paired pulses should be greater than the inactivation at the same time during a continuous pulse. The I channel does not behave according to these predictions, indicating that preferential closed-state inactivation does not explain the slowing of inactivation we observe at positive potentials. Inactivation of the I channel therefore differs both from C-type inactivation, as presently understood, and from the inactivation of Kv2.1., A. Babes, E. Lörinczi, V. Ristoiu, M.L. Flonta, G. Reid., and Obsahuje bibliografii
Gastrointestinal motility is an integrated process including myoelectrical and contractile activity, tone, compliance and transit. The techniques for the assessment of gastrointestinal motility are multiple and all have their advantages and disadvantages. In the case of suspected abnormal upper gut transit, gastric and small bowel transit scintigraphy followed by small intestinal (antroduodenojejunalileal) manometry is recommended. Small bowel manometry can identify patterns suggestive of myopathy, neuropathy or obstruction. Information on procedures, indications, significance, pitfalls and guidelines for small bowel manometry is provided in this paper. In this context the potentials of small intestinal manometry for scientific experimental study of neurohumoral agents, such as serotonin receptor agonists and antagonists, on small intestinal motility is presented., M. B. Hansen., and Obsahuje bibliografii
Soluble leptin receptor (SLR) is the extracellular part of the leptin receptor. This protein is released into circulation and constitutes the main circulating leptin-binding protein. The aim of our study was to measure SLR concentrations in patients with chronic renal failure (CRF) and healthy subjects and to explore the relationship of SLR to other hormones and cytokines. The patients with CRF had significantly higher serum leptin, TNF-a and insulin levels than healthy subjects (25.1±23.5 vs. 9.4±7.6 ng.ml-1 (S.D.); 14.2±4.2 vs. 4.55±2.5 ng.ml-1; 39.8±36.1 vs. 20.3±11.1 mU.l-1). Serum soluble leptin receptor levels did not differ between these groups (19.1±11.3 vs. 19.6±6.1 U.ml-1). An inverse relationship between serum SLR and leptin levels was found in both groups. In patients with CRF the inverse relationship between SLR and insulin, body fat content and total protein levels were also found, while in healthy subjects only inverse relationship of SLR with insulin and albumin concentrations were detected. We conclude that soluble leptin receptor levels in patients with chronic renal failure do not differ from those of healthy subjects despite higher serum leptin levels in CRF patients. The physiological consequences of this finding require further investigation., J. Křížová, S. Sulková, V. Bednářová, E. Kotrlíková, M. Haluzík., and Obsahuje bibliografii
The decapeptide QLNLKEYNLV corresponding to the C-terminus of Gq/G11alpha guanine nucleotide-binding proteins (G-proteins) was synthesized by the solid-phase method and conjugated to keyhole limpet hemocyanin. The rabbits were immunized with these conjugates and an antiserum that reacted specifically with the alpha subunit of Gq/G11 proteins was used in this study. The antiserum exhibited no cross-reactivity with the alpha subunits of stimulatory (Gs) or inhibitory (Gi) G-proteins associated with adenylate cyclase. Immunoblots with the antiserum showed that it specifically recognized the Gq/G11 alpha-proteins in cholate extracts of adipose tissue membranes of goats. Treatment of young castrated male goats with bST had no effect on the quantity of Gq/G11 alpha-subunits in adipose tissue and the results thus obtained did not support the idea that the bST signal in adipose tissue is transmitted via Gq/G11 alpha-proteins., V. Krbeček, H. Kovářů, J. Škarda, T. Barth, J. Velek, V. Žižkovský., and Obsahuje bibliografii
Women with a positive history of gestational diabetes mellitus (GDM) face a higher risk of developing type 2 diabetes mellitus (T2DM) and metabolic syndrome later in life. The higher risk of these metabolic complications is closely associated with adipose tissue. In this review, the importance of adipose tissue is discussed in relation to GDM, focusing on both the quantity of fat deposits and the metabolic activity of adipose tissue in particular periods of life: neonatal age, childhood, adolescence, and pregnancy followed by nursing. Preventive measures based on body composition and lifestyle habits with special attention to the beneficial effects of breastfeeding are also discussed., D. Vejrazkova, M. Vankova, P. Lukasova, J. Vcelak, V. Cirmanova, M. Haluzik, B. Bendlova., and Obsahuje bibliografii
Aldosterone receptor antagonist, spironolactone, has been shown to prevent remodeling of the heart in several models of left ventricular hypertrophy. The aim of the present study was to determine whether the treatment with spironolactone can prevent hypertension, reduction of tissue nitric oxide synthase activity and left ventricular (LV) and aortic remodeling in NG-nitro-L-arginine methyl ester (L-NAME)-induced hypertension. Four groups of rats were investigated: control, spironolactone (200 mg/kg), L-NAME (40 mg/kg) and L-NAME + spironolactone (in corresponding dosage). Animals were studied after 5 weeks of treatment. The decrease of NO-synthase activity in the LV and kidney was associated with the development of hypertension and LV hypertrophy, with increased DNA concentration in the LV, and remodeling of the aorta in the L-NAME group. Spironolactone prevented the inhibition of NO-synthase activity in the LV and kidney and partially attenuated hypertension and LVH development and the increase in DNA concentration. However, remodeling of the aorta was not prevented by spironolactone treatment. We conclude that the aldosterone receptor antagonist spironolactone improved nitric oxide production and partially prevented hypertension and LVH development without preventing hypertrophy of the aorta in NO-deficient hypertension. The reactive growth of the heart and aorta seems to be controlled by different mechanisms in L-NAMEinduced hypertension., F. Šimko, J. Matúšková, I. L'upták, T. Pinčíková, K. Krajčírovičová, S. Štvrtina, J. Pomšár, V. Pelouch, L'. Paulis, O. Pecháňová., and Obsahuje bibliografii
There is virtually no information on spontaneous variability of ECG body surface potential maps (BSPMs) and on dynamics of their reactive changes in healthy subjects. This study evaluated quantitatively the depolarization (QRS) and repolarization (QRST) parameters derived from the respective integral BSPMs, constructed beat-to-beat, from continual body surface ECG records in 9 healthy men resting supine, during head-up tilting and sitting. Spontaneous variability of the BSPMs parameters, both at rest and during postural reactions, was characterized by significant respiratory and low frequency oscillations, more pronounced when related to repolarization. Head-up tilting and sitting-up evoked significant decrease in the QRST-BSPM amplitudes, widening of the angle α and reduction of nondipolarity indexes, compared to the respective supine values. All these changes were gradual, characterized by transition phenomena and prolonged after-effect s. Tilting back to horizontal restored the resting supine va lues. The postural effects on depolarization were individually more variable and in the average showed a minimal QRS-BSPM amplitude increase. Beat-to-beat analysis of a train of ECG BSPMs provided the first evidence of spontaneous, non-random, respiratory and low frequency oscillations of the ventricula r repolarization pattern, and the first insight into the dynamics of body posture associated changes in ventricular recovery., E. Kellerová, V. Szathmáry, G. Kozmann, K. Haraszti, Z. Tarjányi., and Obsahuje bibliografii
NG-nitro-L-arginine-methyl ester (L-NAME)-induced hypertension is associated with protein remodeling of the left ventricle. The aim of the study was to show, whether aldosterone receptor blocker spironolactone and precursor of NOproduction L-arginine were able to reverse the protein rebuilding of the left ventricle. Six groups of male Wistar rats were investigated: control 4 (4 weeks placebo), L-NAME (4 weeks L-NAME), spontaneous-regression (4 weeks L-NAME + 3 weeks placebo), spironolactone-regression (4 weeks L-NAME + 3 weeks spironolactone), L-arginineregression (4 weeks L-NAME + 3 weeks arginine), control 7 (7 weeks placebo). L-NAME administration induced hypertension, hypertrophy of the left ventricle (LV), and the increase of metabolic and contractile as well as soluble and insoluble collagenous protein concentration. The systolic blood pressure and relative weight of the LV decreased in all three groups with regression, while the most prominent attenuation of the LVH was observed after spironolactone treatment. In the spontaneous-regression and L-arginine-regression groups the concentrations of individual proteins were not significantly different from the control value. However, in the spironolactone-regression group the concentration of metabolic, contractile and insoluble collagenous proteins remained significantly increased in comparison with the control group. The persistence of the increased protein concentration in the spironolactone group may be related to the more prominent reduction of myocardial water content by spironolactone., F. Šimko, A. Potáčová, V. Pelouch, L'. Paulis, J. Matúšková, K. Krajčírovičová, O. Pecháňová, M. Adamcová., and Obsahuje bibliografii
Early diagnosis of ongoing malignant disease is crucial to improve survival rate and life quality of the patients and requires sensitive detection of specific biomarkers e.g. prostate-specific antigen (PSA), carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), etc. In spite of current technological advances, malignant diseases are still identified in rather late stages, which have detrimental effect on the prognosis and treatment of the disease. Here, we present a biosensor able to detect fetuin-A, a potential multibiomarker. The biosensing platform is based on polymer brush combining antifouling monomer units of N -(2-hydroxypropyl)methacrylamide (HPMA) and carboxybetaine methacrylamide (CBMAA), statistically copolymerized by surfaceinitiated atom transfer radical polymerization. The copolymer poly(HPMA-co-CBMAA) exhibits excellent non-fouling properties in the most relevant biological media (i.e. blood plasma) as well as antithrombogenic surface properties by preventing the adhesion of blood components (i.e. leukocytes; platelets; and erythrocytes). Moreover, the polymer brush can be easily functionalized with biorecognition elements maintaining high resistance to blood fouling and the binding capacity can be regulated by tuning the ratio between CBMAA and HPMA units. The superior antifouling properties of the copolymer even after biofunctionalization were exploited to fabricate a new plasmonic biosensor for the analysis of fetuin-A in real clinical blood plasma samples. The assay used in this work can be explored as labelfree affinity biosensor for diagnostics of different biomarkers in real clinical plasma samples and to shift the early biomarker detection toward novel biosensor technologies allowing point of care analysis., Z. Riedelová, P. Májek, K. Pečánková, J. Kučerová, F. Surman, A. De Los Pereira, T. Riedel., and Obsahuje bibliografii
Statin-associated myopathy (SAM) represents a broad spectrum of disorders from insignificant myalgia to fatal rhabdomyolysis. Its frequency ranges from 1-5 % in clinical trials to 15-20 % in everyday clinical practice. To a large extent, these variations can be explained by the definition used. Thus, we propose a scoring system to classify statin-induced myopathy according to clinical and biochemical criteria as 1) possible, 2) probable or 3) definite. The etiology of this disorder remains poorly understood. Most probably, an underlying genetic cause is necessary for overt SAM to develop. Variants in a few gene groups that encode proteins involved in: i) statin metabolism and distribution (e.g. membrane transporters and enzymes; OATP1B1, ABCA1, MRP, CYP3A4), ii) coenzyme Q10 production (e.g. COQ10A and B), iii) energy metabolism of muscle tissue (e.g. PYGM, GAA, CPT2) and several others have been proposed as candidates which can predispose to SAM. Pharmacological properties of individual statin molecules (e.g. lipophilicity, excretion pathways) and patients´ characteristics influence the likelihood of SAM development. This review summarizes current data as well as our own results., M. Vrablik, L. Zlatohlavek, T. Stulc, V. Adamkova, M. Prusikova, L. Schwarzova, J. A. Hubacek, R. Ceska., and Obsahuje bibliografii