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1752. The use of egocentric and allocentric reference frames in static and dynamic conditions in humans

Creator:
Moraresku, Sofiia and Vlček, Kamil
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
egocentrismus, egocentrism, spatial processing, functional neuroimaging, reference frames, allocentric, 14, and 612
Language:
English
Description:
The dissociation between egocentric and allocentric reference frames is well established. Spatial coding relative to oneself has been associated with a brain network distinct from spatial coding using a cognitive map independently of the actual position. These differences were, however, revealed by a variety of tasks from both static conditions, using a series of images, and dynamic conditions, using movements through space. We aimed to clarify how these paradigms correspond to each other concerning the neural correlates of the use of egocentric and allocentric reference frames. We review here studies of allocentric and egocentric judgments used in static two- and three-dimensional tasks and compare their results with the findings from spatial navigation studies. We argue that neural correlates of allocentric coding in static conditions but using complex three-dimensional scenes and involving spatial memory of participants resemble those in spatial navigation studies, while allocentric representations in two-dimensional tasks are connected with other perceptual and attentional processes. In contrast, the brain networks associated with the egocentric reference frame in static two-dimensional and three-dimensional tasks and spatial navigation tasks are, with some limitations, more similar. Our review demonstrates the heterogeneity of experimental designs focused on spatial reference frames. At the same time, it indicates similarities in brain activation during reference frame use despite this heterogeneity., Sofiia Moraresku, Kamil Vlcek., and Obsahuje bibliografii
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

1753. The vibration plethysmographic method of arterial compliance analysis in dependence on transmural pressure

Creator:
Jiří Moudr, Jitka Svačinová, Eva Závodná, and Nataša Honzíková
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, tepny, krevní tlak, arteries, blood pressure, arterial compliance, finger arterial pressure, plethysmography, transmural arterial pressure, frequency characteristic, 14, and 612
Language:
English
Description:
The aim of this study was to obtain a detailed analysis of the relationship between the finger arterial compliance C [ml/mm Hg] and the arterial transmural pressure Pt [mm Hg]. We constructed a dynamic plethysmograph enabling us to set up a constant pressure Pcss [mm Hg] and a superimposed fast pressure vibration in the finger cuff (equipped with a source of infra-red light and a photoelectric sensor for the measurement of arterial volume). Pcss could be set on the required time interval in steps ranging between 30 and 170 mm Hg, and on sinusoidal pressure oscillation with an amplitude Pca (2 mm Hg) and a frequency f (20, 25, 30, 35, 40 Hz). At the same time continuous blood pressure BP was measured on the adjacent finger (Portapres). We described the volume dependence of a unitary arterial length on the time-varying transmural pressure acting on the arterial wall (externally Pcss+Pca.sin(2πf), internally BP) by a second-order differential equation for volume. This equation was linearized within a small range of selected BP. In the next step, a Fourier transform was applied to obtain the frequency characteristic in analytic form of a complex linear combination of frequency functions. While series of oscillations [Pca, f] were applied for each Pcss, the corresponding response of the plethysmogram was measured. Amplitude spectra were obtained to estimate coefficients of the frequency characteristic by regression analysis. We determined the absolute value: elastance E, and its inverse value: compliance (C=1/E). Then, C=C(Pt) was acquired by applying sequences of oscillations for different Pcss (and thus Pt) by the above-described procedure. This methodology will be used for the study of finger arterial compliance in different physiological and pathological conditions., J. Moudr, J. Svačinová, E. Závodná, N. Honzíková., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1754. The VO2-on kinetics in constant load exercise sub-anaerobic threshold reflects endothelial function and dysfunction in muscle microcirculation

Creator:
Maione, D., Cicero, A. F. G., Bacchelli, S., Cosentino, E. R., Degli Esposti, D., Manners, D. N., Rinaldi, E. R., Rosticci, M., Senaldi, R., Ambrosioni, E., and Borghi, C.
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Type:
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Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, anaerobic threshold, constant load exercise, endothelial function, O2 consumption, 14, and 612
Language:
English
Description:
To propose a test to evaluate endothelial function, based on VO 2 on-transition kinetics in sub -anaerobic threshold (AT) constant load exercise, we tested healthy subjects and patients with ischemic -hypertensive cardiopathy by two cardiopulmonary te sts on a cycle ergometer endowed with an electric motor to overcome initial inertia: a pre-test and, after at least 24 h, one 6 min constant load exercise at 90 % AT. We measured net phase 3 VO2-on kinetics and, by phase 2 time constant (τ), valued endothe lial dysfunction. We found shorter τ in repeated tests, shorter time between first and second test, by persisting endothelium -dependent arteriolar vasodilatation and/or several other mechanisms. Reducing load to 80 % and 90 % AT did not produce significant changes in τ of healthy volunteers, while in heart patients an AT load of 70 %, compared to 80 % AT, shortened τ(∆=4.38±1.65s, p=0.013). In heart patients, no correlation was found between NYHA class, ejection fraction (EF), and the two variables derived from incremental cycle cardio - pulmonary exercise, as well as between EF and τ; while NYHA class groups were well correlated w ith τ duration (r=0.92, p=0.0001). Doxazosin and tadalafil also significantly reduced τ. In conclusion, the O2 consumption kinetics during the on transition of constant load exercise below the anaerobic threshold are highly sensitive to endothelial functi on in muscular microcirculation, and constitute a marker for the evaluation of endothelial dysfunction. and D. Maione, A. F. G. Cicero, S. Bacchelli, E. R. Cosentino, D. Degli Esposti, D. N. Manners, E. R. Rinaldi, M. Rosticci, R. Senaldi, E. Ambrosioni, C. Borghi.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1755. Theoretical investigations into the variability of the 15N solid-state NMR parameters within an antimicrobial peptide ampullosporin A

Creator:
Czernek, J and Jiří Brus
Format:
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Type:
model:article and TEXT
Subject:
peptidy, peptids, antimicrobial peptides, ampullosporin A, amidic bond, NMR, DFT, 14, and 612
Language:
English
Description:
The solid-state NMR measurements play an indispensable role in studies of interactions between biological membranes and peptaibols, which are amphipathic oligopeptides with a high abundance of α-aminobutyric acid (Aib). The solid-state NMR investigations are important in establishing the molecular models of the pore forming and antimicrobial properties of peptaibols, but rely on certain simplifications. Some of the underlying assumptions concern the parameters describing the 15N NMR chemical shielding tensor (CST) of the amide nitrogens in Aib and in conventional amino acids. Here the density functional theory (DFT) based calculations were applied to the known crystal structure of one of peptaibols, Ampullosporin A, in order to explicitly describe the variation of the 15N NMR parameters within its backbone. Based on the DFT computational data it was possible to verify the validity of the assumptions previously made about the differences between Aib and other amino acids in the isotropic part of the CST. Also the trends in the magnitudes and orientations of the anisotropic components of the CST, as revealed by the DFT calculations of the full periodic structure of Ampullosporin A, were thoroughly analyzed, and may be employed in future studies of peptaibols., J. Czernek, J. Brus., and Obsahuje bibliografii
Rights:
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1756. Three months of regular aerobic exercise in patients with obesity improve systemic subclinical inflammation without major influence on blood pressure and endocrine production of subcutaneous fat

Creator:
Trachta, P., Drápalová, J., Petra Kaválková, Toušková, V., Cinkajzlová, A., Zdeňka Lacinová, Martin Matoulek, Tomáš Zelinka, Jiří Widimský, Miloš Mráz, and Martin Haluzík
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Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, obezita, obesity, physical activity, adipose tissue, proinflammatory factors, 14, and 612
Language:
English
Description:
The aim of our study was to explore the effects of regular aerobic exercise on anthropome tric, biochemical and hormonal parameters and mRNA expression of selected factors involved in metabolic regulations in subcutaneous adipose tissue of patients with obesity. Fifteen obese wome n with arterial hypertension underwent a three-month exercise program consisting of 30 min of aerobic exercise 3 times a we ek. Fifteen healthy lean women with no intervention served as a control group. Obese group underwent anthropometric measurements, blood sampling, subcutaneous adipose tissue (SCAT) biopsy and 24-h blood pressure monitoring at baseline and after three months of exercise, while control group was examined only once. At baseline, obese group had increased SCAT expression of proinflammatory cytokines and adipokines relative to control group. Three months of regular exercise improved anthropometric parameters, decreased CRP, blood glucose and HOMA-IR, while having no significant effect on lipid profile and blood pressure. Gene expressions in SCAT were not affected by physical activity with the exce ption of increased aquaporin-3 mRNA expression. We conclude that three months of regular exercise decrease systemic subc linical inflammation with only minor influence on the blood pressure and the endocrine function of subcutaneous fat., P. Trachta, J. Drápalová, P. Kaválková, V. Toušková, A. Cinkajzlová, Z. Lacinová, M. Matoulek, T. Zelinka, J. Widimský Jr., M. Mráz, M. Haluzík., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1757. Three types of ion channels in the cell membrane of mouse fibroblasts

Creator:
Koselksi, M., Olszewska, A., Hordyjewska, A., Małecka-Massalska, T., and Trebacz, K.
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, buněčné membrány, cell membranes, patch-clamp, mouse fibroblast, cation channels, K+ channels, anion channels, 14, and 612
Language:
English
Description:
Patch clamp recordings carried out in the inside-out configuration revealed activity of three kinds of channels: nonselective cation channels, small-conductance K+ channels, and large-conductance anion channels. The nonselective cation channels did not distinguish between Na+ and K+. The unitary conductance of these channels reached 28 pS in a symmetrical concentration of 200 mM NaCl. A lower value of this parameter was recorded for the small-conductance K+ channels and in a 50-fold gradient of K+ (200 mM/4 mM) it reached 8 pS. The high selectivity of these channels to potassium was confirmed by the reversal potential (-97 mV), whose value was close to the equilibrium potential for potassium (-100 mV). One of the features of the large - conductance anion channels was high conductance amounting to 493 pS in a symmetrical concentration of 200 mM NaCl. The channels exhibited three subconductance levels. Moreover, an increase in the open probability of the channels at voltages close to zero was observed. The anion selectivity of the channels was low, because the channels were permeable to both Cl - and gluconate - a large anion. Research on the calcium dependence revealed t hat internal calcium activates nonselective cation channels and small-conductance K+ channels, but not large - conductance anion channels., M. Koselski, A. Olszewska, A. Hordyjewska, T. Małecka-Massalska, K. Trebacz., and Obsahuje bibliografii
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

1758. Three-dimensional electrogram in spherical coordinates: application to ischemia analysis

Creator:
Oto Janoušek, Kolářová, J., Marie Nováková, and Ivo Provazník
Format:
print
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, ischemie, ischemia, three dimensional electrogram, vectorcardiogram, spatiocardiogram, vectorcardiography parameters, myocardial ischemia, 14, and 612
Language:
English
Description:
Three-dimensional electrogram was used for analysis of ischemia manifestation in isolated hearts. Three parameters based on spherical coordination system were used in this study - amplitude of electrical heart vector, its azimuth and elevation. The parameters were presented as a trend. This approach reflected ischemic changes in a manner which can be easily observed and evaluated. Ischemia was analysed in seven isolated hearts of New Zealand white rabbits. It was found that (a) ischemia changes heart electric vector, (b) ischemic preconditioning has a protective effect, and (c) both of these findings can be clearly observed by the proposed method., O. Janoušek ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1759. Thyroid hormone abnormalities in hemodialyzed patients: low triiodothyronine as well as high reverse triiodothyronine are associated with increased mortality

Creator:
Horáček, J., Sylvie Sulková, Kubišová, M., Roman Šafránek, Eva Malířová, Marta Kalousová, Svilias, I., Jaroslav Malý, Luboš Sobotka, and Pavel Žák
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, thyroid, triiodothyronine, reverse triiodothyronine, hemodialysis, survival, 14, and 612
Language:
English
Description:
Numerous abnormalities of thyroid hormones in end-stage renal disease (ESRD) have been described. Our aim was to analyze the impact of these abnormalities on survival. In 167 hemodialyzed ESRD patients, TSH and thyroid hormone levels (T4, fT4, T3, fT3, rT3) were determined. The patients were then prospectively followed up for up to 5 years and the possible impact of any observed abnormalities on their mortality was studied. Only 16.8 % patients had all six tests within the reference range. The pattern of nonthyroidal illness syndrome was found in 56.3 %. Low T3 was particularly common (44.3 %), and clearly associated with increased 6- and 12-month mortality and decreased overall survival (log rank test, P=0.007). Independent of T3 levels (Spearman correlation, NS), increased rT3 was more frequently observed (9.9 %) than expected from the literature, and was also related to increased mortality and decreased survival (log rank test, P=0.021). Increased rT3 may be more common in ESRD patients than previously described, and together with decreased T3 it may serve as an indicator of poor prognosis in subsequent months., J. Horáček ... [et al.]., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1760. Thyroid nodules: pathophysiological insight on oncogenesis and novel diagnostic techniques

Creator:
Krátký, J., Vítková, H., Bartáková, J., Zdeněk Telička, Antošová, M., Zdeňka Límanová, and Jan Jiskra
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, rakovina štítné žlázy, těhotenství, thyroid cancer, pregnancy, thyroid nodule, thyroid autoimmunity, hypothyroidism, BRAF mutation, RAS mutation, Thyroid ultrasound, microcalcifications, thyroid elastrography, 14, and 612
Language:
English
Description:
Thyroid nodules are a very frequent pathology among common population. Despite the vast majority of them are of benign origin, the incidence of thyroid cancer is currently rather rising. Although there are several risk factors of thyroid cancer and several clinical, ultrasound, biochemical and molecular diagnostic markers, the exact mechanisms of thyroid oncogenesis and the linkage between thyroid nodule ultrasound appearance and its biological character remain unclear. While ionizing radiation is the only one well-known risk factor for thyroid cancer, the significance of some others remains unclear. The aim of our review was to discuss some not completely known pathophysiological mechanisms involved in thyroid oncogenesis as hypothyroidism, mutations of genes regulating cell proliferation, thyroid autoimmunity and pregnancy and to describe pathophysiological background of some ultrasound markers of thyroid cancer (size, echogenicity, vascularization, calcifications and stiffness). Better knowledge in this field is crucial for development of novel diagnostic techniques and therapeutic approaches. For exampl e, the analysis of BRAF, RAS and other mutations in cytological samples may help to distinction between follicular thyroid carcinoma and follicular thyroid adenoma and may signific antly decrease the number of unnecessary surgery among patients with thyroid nodules. Alternatively, the different malign cells growth, angiogenesis, destructions of thyroid follicles, reparative changes, growth retardation, fibrosis and increased interstitial fluid pressure implicate the typical ultrasound appearance of papillary thyroid cancer (hypoechogenicity, irregular vascularization, microcalcifications, stiffness) which is essential to catch the suspicious nodules on the basis of their ultrasound appearance among large amount of benign nodules., J. Krátký, H. Vítková, J. Bartáková, Z. Telička, M. Antošová, Z. Límanová, J. Jiskra., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public