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72. Mechanism of Na+ Deprivation-Induced Catecholamine Secretion From Freshly Isolated Bovine Adrenal Chromaffin Cells

Creator:
Isosaki, M. and Nakashima, T.
Format:
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Type:
article, studie, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Na+-Ca2+ exchange, Na+ deprivation, Catecholamine secretion, Adrenal medulla · Chromaffin, 14, and 612
Language:
English
Description:
We have studied the mechanism of Na+ deprivation-induced catecholamine secretion from freshly isolated bovine adrenal chromaffin cells. Na+ deprivation-induced catecholamine secretion depended on free extracellular Ca2+ concentrations and was almost parallel to 45Ca2+ influx into the cells under various experimental conditions. Furthermore, Na+ deprivation-induced 45Ca2+ influx and catecholamine secretion were actually induced by a relative Na+ concentration gradient across the plasma membrane, but not by simple omission of Na+ from the medium. These results indicate that the deprivation of Na+ from the medium changes the relative Na+ gradient across the plasma membrane and results in Ca2+ influx via a reverse mode of Na+-Ca2+ exchange rather than by inducing Ca2+ entry through Ca2+ channels by eliminating the competition between extracellular Na+ and Ca2+., M. Isosaki, T. Nakashima., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

73. Mismatch of Local Blood Flow and Oxidative Metabolism in Stunned Myocardium

Creator:
Schwanke, U., Heusch, G., and Schipke, J. D.
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Type:
article, studie, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Myocardial stunning, Local blood flow, Local oxidative metabolism, Perfusion-metabolism mismatch, Heterogeneity, 14, and 612
Language:
English
Description:
Myocardial blood flow is spatially heterogeneous, reflecting non-uniform oxygen supply. Also, myocardial oxida-tive metabolism is spatially heterogeneous. The effects of acute ischemia and reperfusion on the rela-tionship between local myocardial blood flow (LMF) and oxi-dative metabolism are still unknown. LMF was measured in isolated, blood-perfused rabbit hearts using colored microspheres and oxidation water labeled with 18O2 (H218O). Three protocols were performed: 18O2-perfusion during normoxia (N; n=7), during early reperfusion (ER; 10 min, n=6), and late reperfusion (LR; 40 min, n=6) following 20 min no-flow ischemia. LMF and local H218O residues were determined within defined myocardial samples (105 ± 15 mg). For interindividual comparison, values were normalized to the mean of the individual experiment and expressed as percentages. LMF ranged from 18 to 193 % (N), 12 to 250 % (ER), and 11 to 180 % (LR). The H218O tissue residue ranged from 63 to 132 % (N), 73 to 142 % (ER) and 32 to 148 % (LR). The correlation between LMF and local oxidative metabolism during N (r=0.77; n=56) was lost in the postischemic heart during ER and LR. LMF during N and ER were only weakly correlated (r=0.24; n=48), whereas LMF during N and LR correlated well (r=0.87; n=48). It is concluded that the heterogeneous LMF pattern at baseline is maintained in the stunned myocardium whereas that of local oxidative metabolism is not. Apart from the established mechanisms underlying myocardial stunning, a mismatch between local flow and oxidative metabolism might also con-tribute., U. Schwanke, G. Heusch, J. D. Schipke., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

74. Model of Spike Propagation Reliability Along the Myelinated Axon Corrupted by Axonal Intrinsic Noise Sources

Creator:
Eduard Kuriščák, Stanislav Trojan, and Wünsch, Z.
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Type:
article, studie, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Axons, Action Potentials, Stochastic Processes, Computer Simulation, Ion Channels, 14, and 612
Language:
English
Description:
We investigated how selected electromorphological parameters of myelinated axons influence the preservation of interspike intervals when the propagation of action potentials is corrupted by axonal intrinsic noise. Hereby we tried to determine how the intrinsic axonal noise influences the performance of axons serving as carriers for temporal coding. The strategy of this coding supposes that interspike intervals presented to higher order neurons would minimally be deprived of information included in interspike intervals at the axonal initial segment. Our experiments were conducted using a computer model of the myelinated axon constructed in a software environment GENESIS (GEneral NEural SImulation System). We varied the axonal diameter, myelin sheath thickness, axonal length, stimulation current and channel distribution to determine how these parameters influence the role of noise in spike propagation and hence in preserving the interspike intervals. Our results, expressed as the standard deviation of spike travel times, showed that by stimulating the axons with regular rectangular pulses the interspike intervals were preserved with a microsecond accuracy. Stimulating the axons with pulses imitating postsynaptic currents, greater changes of interspike intervals were found, but the influence of implemented noise on the jitter of interspike intervals was approximately the same., E. Kuriščák, S. Trojan, Z. Wünsch., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

75. Model of Visually Evoked Cortical Potentials

Creator:
Kremláček, J., Kuba, M., and Holčík, J.
Format:
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Type:
article, studie, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Mathematical model, Visual evoked potentials, Pattern-reversal, Motion-onset, 14, and 612
Language:
English
Description:
The pattern-reversal (P-VEPs) and the motion-onset (M-VEPs) of visual evoked potentials were modeled by means of three damped oscillators (O1, O2, O3) of identical construction. The O1, assumed to simulate the response of primary visual area (V1), was driven by the firing density of the lateral geniculate nuclei. O1 contributed mainly to the N75 and P100 peaks of the P-VEPs. The O2, driven by the O1 output, mimics the activity of V2, V3a, and MT. It contributed to the negative peak N145 of the P-VEPs or to the N160 in the M-VEPs. The O3 was suggested to model late slow processes probably of an attentive origin. The model parameters were set by optimization to follow the P-VEPs and M-VEPs obtained as a grand average of four young volunteers (PZ - A2 lead). The evoked potentials were described with normalized root mean square error lower than 13 %., J. Kremláček, M. Kuba, J. Holčík., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

76. Moravské prameny mešní tvorby Antonia Caldary: problém autenticity

Creator:
Jana Spáčilová
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Type:
article, studie, studies, model:article, and TEXT
Subject:
Caldara, Antonio, 1670-1736, 18. století, archivní fondy, hudební rukopisy, hudební skladatelé, muzikologie, mše (hudba), archives, composers, mass (music), music manuscripts, musicology, Morava (Česko), Moravia (Czechia), 78.01, 783.21, 78.071.1, 091:78, 930.253, and (048.8)
Language:
Czech
Description:
Studie Jany Spáčilové se zabývá mešními kompozicemi hudebního skladatele Antonia Caldary, dochovanými v moravských hudebních sbírkách., This article is dedicated to the problem of the erroneous attribution of authorship of Masses to Antonio Caldara in Moravian collections of church music. It contains information about extant records of Masses by Caldara and methodological discussion concerning the reliability of sources with respect to authorship. Also included is an overview of Caldara sources of Moravian provenience, including both extant music and entries in period inventories. Attention is dedicated both to compositions by others regarded in Moravia as works by Antonio Caldara, and to works by Caldara under the names of other composers. Works identified as having been written by other composers are presented in the form of tables, including signatures of all concordant sources found so far in European libraries. The purpose of the article is to give an idea of the standing of Caldara’s works in the repertoire of Moravian church music and to prepare material for a future thematic catalog of Moravian sources of Masses by Caldara., Jana Spáčilová., Rubrika: Studie, and Anglické resumé na s. 75, anglický abstrakt 45.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

77. Multinuclear NMR Studies of an Actively Dividing Artificial Tumor

Creator:
Shankland, E. G., Livesey, J. C., Wiseman, R. W., and Krohn, K. A.
Format:
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Type:
article, studie, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, A549, Phophorous, NMR, Cell culture, 14, and 612
Language:
English
Description:
Growth of the A549 cell line in a perfusion system suitable for use in a magnetic resonance study has been characterized and shown to be stable physiologically and hence appropriate for serial observations. Several methods of monitoring cell growth were compared to assess the behavior of the cells in this system. Comparison between NMR metabolite data and cell growth via cell counting showed that 31P NMR signals accurately reported cell doubling time. In contrast to most NMR cell culture systems, viable cells can be recovered from the perfusion system after the NMR measurements for further biochemical studies. These data further suggest that this system will be useful for studying the physiology and biochemistry of exponentially growing cells for at least two days in NMR tube culture., E. G. Shankland, J. C. Livesey, R. W. Wiseman, K. A. Krohn., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

78. Myofibrillar Creatine Kinase Activity Inferred from a 3D Model

Creator:
Jiří Mejsnar, Sopko, B., and Gergor, M.
Format:
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Type:
article, studie, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Muscle, Energetics, Myofibrillar creatine kinase, 14, and 612
Language:
English
Description:
Myofibrillar creatine kinase (CK) that buffers ATP during fluctuating muscle energy metabolism has been selected for studies of conformational changes underlying the cellular control of enzyme activity. The force field was computed for three energetic states, namely for the substrate-free CK molecule, for the molecule conjugated with the MgATP complex, and for the molecule conjugated with the pair of reactants MgATP-creatine. Without its substrates, the enzyme molecule assumes an inactive "open" form. Upon binding of the MgATP complex, the CK molecule takes up a reactive "closed" conformation. Subsequent binding of creatine yields a nonreactive "intermediary" conformation. Acid-base catalysis is considered to be the basic principle for the reversible transfer of the phosphoryl group between the substrates. The results indicate that the substrate-induced energy minimizing conformational changes do not represent a sufficient condition for CK activity and that some other essential component of physiological control at the cellular level is involved in the transition from the intermediary to the closed structure of the molecule., J. A. Mejsnar, B. Sopko, M. Gergor., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

79. Narativní komplexita

Creator:
Vladimír Chrz and Ivo Čermák
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Type:
article, studie, model:article, and TEXT
Subject:
Psychologie, psychologie, psychology, integrace, narativní transformace, potíž, narrative complexity, differentiation, integration, narrative transformation, trouble, 17, and 159.9
Language:
Czech
Description:
V článku je předložen model narativní komplexity. Jako východiska modelu jsou využity Todorovův pojem „narativní transformace“ a Brunerův koncept „potíž“. Narativní transformace je chápána jako to, „co vyprávění dělá s konstitutivní potíží“. S využitím těchto pojmů je narativní komplexita definována jako diferenciace a integrace různých aspektů narativní transformace. Pojem narativní komplexita poukazuje jak k dispozici, tak také k procesu i výsledku narativního ztvárnění zkušenosti v její složitosti, úplnosti a proměnlivosti. Model umožňuje včlenit do jednoho logicky konzistentního rámce různé aspekty narativní komplexity, tak jak byly doposud koncipovány z různých dílčích teoretických či praktických hledisek. Předložený model sestává z osmi souvisejících aspektů: 1) diferenciace a integrace tématu vyprávění, 2) diferenciace a integrace aktérství, 3) diferenciace a integrace narativní konstrukce, 4) diferenciace a integrace ztvárnění hodnot a přesvědčení, 5) diferenciace a integrace na rovině reflexe, 6) diferenciace a integrace hledisek a perspektiv, 7) diferenciace a integrace utváření postav, 8) diferenciace a integrace na rovině komunikačního a sociokulturního kontextu. Na závěr jsou zmíněny některé teoretické a empirické možnosti předloženého modelu., Model of narrative complexity is articulated. Todorov’s concept of “narrative transformation” and Bruner’s concept of “trouble” are used as a frame of narrative complexity conceptualization. Narrative transformation is presented as “something what story telling does with constitutive trouble”. Narrative complexity is thus defined as a differentiation and integration of various aspects of narrative transformation. Narrative complexity refers both to disposition and also to the process and to the result of narrative experience constructing in its complicatedness, completeness, and changeableness. The model enables to incorporate various aspects of narrative complexity from different theoretical and practical perspectives into one consistent framework. The presented model consists of eight interconnected aspects: 1) differentiation and integration of topic storytelling, 2) differentiation and integration of agency, 3) differentiation and integration of narrative construction, 4) differentiation and integration of values and believes embodiment, 5) differentiation and integration at the level of reflection, 6) differentiation and integration of different perspectives, 7) differentiation and integration of characters (protagonists), 8) differentiation and integration in communication and socio-cultural contexts. Theoretical and empirical consequences of the model are also discussed., Vladimír Chrz, Ivo Čermák., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

80. Nitric Oxide Synthase Inhibition and Glutamate Binding in Quinolinate-Lesioned Rat Hippocampus

Creator:
Václav Lisý and František Šťastný
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Type:
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Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Quinolinic acid, NMDA receptor, Membrane binding, Nitric oxide synthase (NOS), Neurodegeneration, 14, and 612
Language:
English
Description:
a1_The effect of lesions induced by bilateral intracerebroventricular (ICV) injection of quinolinate (250 nmol of QUIN/ventricle), a selective N-methyl-D-aspartate (NMDA) receptor agonist, on [3H]glutamate ([3H]Glu) binding to the main types of both ionotropic and metabotropic glutamate receptors (iGluR and mGluR) was investigated in synaptic membrane preparations from the hippocampi of 50-day-old rats. The membranes from QUIN injured brains revealed significantly lowered binding in iGluR (by 31 %) as well as in mGluR (by 22 %) as compared to the controls. Using selected glutamate receptor agonists as displacers of [3H]Glu binding we found that both the NMDA-subtype of iGluR and group I of mGluR are involved in this decrease of binding. Suppression of nitric oxide (NO) production by NG-nitro-L-arginine (50 nmol of NARG/ventricle) or the increase of NO generation by 3-morpholinylsydnoneimine (5 nmol of SIN-1/ventricle) failed to alter [3H]Glu or [3H]CPP (3-((D)-2-carboxypiperazin-4-yl)-[1,2-3H]-propyl-1-phosphonic acid; NMDA-antagonist) binding declines caused by QUIN-lesions. Thus, our findings indicate that both the NMDA-subtype of iGluR and group I of mGluR are susceptible to the QUIN-induced neurodegeneration in the rat hippocampus. However, the inhibition of NO synthesis did not reveal any protective action in the QUIN-evoked, NMDA-receptor mediated decrease of [3H]Glu binding., a2_Therefore, the additional mechanisms of QUIN action, different from direct NMDA receptor activation/NO production (e.g. lipid peroxidation induced by QUIN-Fe-complexes) cannot be excluded., V. Lisý, F. Šťastný., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public