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  • 1
    Electronic Resource
    Electronic Resource
    High-temperature nematic liquid crystal for gas liquid chromatography (1980)
    s.l. : American Chemical Society
    Analytical chemistry 52 (1980), S. 2417-2420 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac50064a042
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  • 2
    Electronic Resource
    Electronic Resource
    Quality factor inversion determination from the analysis of body wave data (1967)
    Springer
    Pure and applied geophysics 67 (1967), S. 15-26 
    Details
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary In this investigation, a method is developed which allows the determination of the distribution of the intrinsic attenuation with depth in the earth's mantle using single body wave observations. Focal mechanism, geometrical spreading and the source function are not involved in the proposed method. Several examples are presented obeying different laws of the quality factor decreasing or increasing with depth. A case is shown where a first order discontinuity is present, and also when the hypocenter varies with depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00880557
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  • 3
    Electronic Resource
    Electronic Resource
    Modulation of the inwardly rectifying K+ channel in isolated human atrial myocytes by α1-adrenergic stimulation (1995)
    Springer
    The journal of membrane biology 148 (1995), S. 185-191 
    Details
    ISSN: 1432-1424
    Keywords: Inwardly rectifying K+ channel ; Patch ; clamp technique ; Human atrial myocytes ; Methox ; amine ; Protein kinase C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have examined the α1-adrenergic modulation of the inwardly-rectifying K+ channel (I K1) in isolated human atrial myocytes using the patch clamp technique. α1-Adrenergic agonist methoxamine produced action potential prolongation and a depolarization of the resting membrane potential. Under whole-cell voltage clamp conditions, bath application of methoxamine can inhibit macroscopic I K1. The methoxamine-induced inhibition was reversible and concentration dependent, with the concentration for half-maximal inhibition being 18 μm. The methoxamine-induced inhibition of I K1 was prevented by bath application of α1-adrenergic blocker prazosin. The current was similarly inhibited by phorbol ester (PMA), an activator of protein kinase C (PKC). In contrast, methoxamine failed to inhibit the current in the presence of a specific PKC inhibitor H-9, suggesting that PKC is involved in the methoxamine-induced inhibition of I K1. In single channel recording from cell attached patches, bath-applied methoxamine could suppress I K1 channels by decreasing the frequency and duration of bursting without affecting unitary amplitude. Direct application of purified PKC to excised inside-out patches inhibited channel activity similar to methoxamine in cell-attached patches. The PKC selective inhibitor, PKC19-36, prevented the PKC-induced inhibition of the channel. We conclude that human atrial I K1 can be inhibited by α1-adrenergic stimulation via PKC-dependent pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00207274
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of the Stretch-activated Chloride Channel in Isolated Human Atrial Myocytes (1998)
    Springer
    The journal of membrane biology 163 (1998), S. 67-76 
    Details
    ISSN: 1432-1424
    Keywords: Key words: Patch-clamp technique — Stretch-activated Cl− channel — Human atrial myocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract: Macroscopic and unitary currents through stretch-activated Cl− channels were examined in isolated human atrial myocytes using whole-cell, excised outside-out and inside-out configurations of the patch-clamp technique. When K+ and Ca2+ conductances were blocked and the intracellular Ca2+ concentration ([Ca2+] i ) was reduced, application of positive pressure via the pipette activated membrane currents under whole-cell voltage-clamp conditions. The reversal potential of the current shifted by 60 mV per 10-fold change in the external Cl− concentration, indicating that the current was Cl− selective. The current was inhibited by bath application of 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) and 9-anthracenecarboxylic acid (9-AC). β-Adrenergic stimulation failed to activate a Cl− current. In single channel recordings from outside-out patches, positive pressure in the pipette activated the unitary current with half-maximal activation of 14.7 mm Hg at +40 mV. The current-voltage relationship of single channel activity obtained in inside-out patches was linear in symmetrical Cl− solution with the averaged slope conductance of 8.6 ± 0.7 pS (mean ±sd, n= 10). The reversal potential shift of the channel by changing Cl− concentration was consistent with a Cl− selective channel. The open time distribution was best described by a single exponential function with mean open lifetime of 80.4 ± 9.6 msec (n= 9), while at least two exponentials were required to fit the closed time distributions with a time constant for the fast component of 11.5 ± 2.2 msec (n= 9) and that for the slow component of 170.2 ± 21.8 msec (n= 9). Major changes in the single channel activity in response to pressure were caused by changes in the interburst interval. Single channel activity was inhibited by DIDS and 9-AC in a manner similar to whole-cell configuration. These results suggest that membrane stretch induced by applying pressure via the pipette activated a Cl− current in human atrial myocytes. The current was sensitive to Cl− channel blockers and exhibited membrane voltage-independent bursting opening without sensitive to β-adrenergic stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002329900371
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  • 5
    Electronic Resource
    Electronic Resource
    Activation of Inwardly Rectifying Potassium Channels by Muscarinic Receptor-linked G Protein in Isolated Human Ventricular Myocytes (1997)
    Springer
    The journal of membrane biology 157 (1997), S. 71 -81 
    Details
    ISSN: 1432-1424
    Keywords: Key words: Patch-clamp technique — Human ventricular myocytes — G proteins — Muscarinic K+ channel — Inwardly-rectifying K+ channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Muscarinic receptor-linked G protein, G i , can directely activate the specific K+ channel (I K(ACh)) in the atrium and in pacemaker tissues in the heart. Coupling of G i to the K+ channel in the ventricle has not been well defined. G protein regulation of K+ channels in isolated human ventricular myocytes was examined using the patch-clamp technique. Bath application of 1 μm acetylcholine (ACh) reversibly shortened the action potential duration to 74.4 ± 12.1% of control (at 90% repolarization, mean ±sd, n= 8) and increased the whole-cell membrane current conductance without prior β-adrenergic stimulation in human ventricular myocytes. The ACh effect was reversed by atropine (1 μm). In excised inside-out patch configurations, application of GTPγS (100 μm) to the bath solution (internal surface) caused activation of I K(ACh) and/or the background inwardly-rectifying K+ channel (I K1) in ventricular cell membranes. I K(ACh) exhibited rapid gating behavior with a slope conductance of 44 ± 2 pS (n= 25) and a mean open lifetime of 1.8 ± 0.3 msec (n= 21). Single channel activity of GTPγS-activated I K1 demonstrated long-lasting bursts with a slope conductance of 30 ± 2 pS (n= 16) and a mean open lifetime of 36.4 ± 4.1 msec (n= 12). Unlike I K(ACh), G protein-activated I K1 did not require GTP to maintain channel activity, suggesting that these two channels may be controlled by G proteins with different underlying mechanisms. The concentration of GTP at half-maximal channel activation was 0.22 μm in I K(ACh) and 1.2 μm in I K1. Myocytes pretreated with pertussis toxin (PTX) prevented GTP from activating these channels, indicating that muscarinic receptor-linked PTX-sensitive G protein, G i , is essential for activation of both channels. G protein-activated channel characteristics from patients with terminal heart failure did not differ from those without heart failure or guinea pig. These results suggest that ACh can shorten the action potential by activating I K(ACh) and I K1 via muscarinic receptor-linked G i proteins in human ventricular myocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002329900217
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of the acetylcholine-sensitive muscarinic K+ channel in isolated feline atrial and ventricular myocytes (1995)
    Springer
    The journal of membrane biology 145 (1995), S. 143-150 
    Details
    ISSN: 1432-1424
    Keywords: Patch clamp technique ; Acetylcholine ; Muscarinic K+ channel ; GTP — G protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract M2-cholinergic receptor activation by acetylcholine (ACh) is known to cause a negative inotropic and chronotropic action in atrial tissues. This effect is still controversial in ventricular tissues. The ACh-sensitive muscarinic K+ channel (I K(ACh)) activity was characterized in isolated feline atrial and ventricular myocytes using the patch-clamp technique. Bath application of ACh (1 μm) caused shortening of action potential duration without prior stimulation with catecholamines in atrial and ventricular myocytes. Resting membrane potential was slightly hyperpolarized in both tissues. These effects of ACh were greater in atrium than in ventricle. ACh increased whole-cell membrane current in atrial and ventricular myocytes. The current-voltage (I-V) relationship of the ACh-induced current in ventricle exhibited inward-rectification whose slope conductance was smaller than that in atrium. In single channel recording from cell-attached patches, I K(ACh) activity was observed when ACh was induced in the pipette solution in both tissues. The channel exhibited a slope conductance of 47 ±1 pS (mean ± sd, n=14) in atrium and 47 ±2 pS (n= 10) in ventricle (not different statistically; ns). The open times were distributed according to a single exponential function with mean open lifetime of 2.0±0.3 msec (n= 14) in atrium and 1.9±0.3 msec (n=10) in ventricle (ns); these conductance and kinetic properties were similar between the two tissues. However, the relationship between the concentration of ACh and single channel activity showed a higher sensitivity to ACh in atrium (IC 50 =0.03 μm) than in ventricle (IC 50 =0.15 μm). In excised inside-out patches, ventricular I K(ACh) required higher concentrations of GTP to activate the channel compared to atrial channels. These results suggest a reduced I K(ACh) channel sensitivity to M2-cholinergic receptor-linked G protein (Gi) in ventricle compared to atrium in feline heart.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237372
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  • 7
    Electronic Resource
    Electronic Resource
    Information transmission in multi-input-output stochastic neuron models (1979)
    Springer
    Biological cybernetics 34 (1979), S. 119-124 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The Shannon's information theory in multiway channels (Shannon, 1961) is applied to multi-input-output relations of the stochastic automaton models for interaction of excitatory and inhibitory impulse sequences proposed in the previous papers (Tsukada et al., 1977). In these models, the output spike train depends upon several statistical characteristics (mean frequency, standard deviation, form, order-dependence or order-independence, etc.) of the excitatory and inhibitory input spike trains. By the use of the multiple-access channel in information theory, some stochastic properties of temporal pattern discrimination in neurons are analyzed and discussed with biological systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00365476
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  • 8
    Electronic Resource
    Electronic Resource
    Temporal pattern discrimination of impulse sequences in the computer-simulated nerve cells (1975)
    Springer
    Biological cybernetics 17 (1975), S. 19-28 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract This paper deals with some properties of temporal pattern discrimination performed by single digital-computer simulated synaptic cells. To clarify these properties, the Shannon's entropy method which is a basic notion in the information theory and a fundamental approach for the design of pattern classification system was applied to input-output relations of the digital computer simulated synaptic cells. We used the average mutual information per symbol as a measure for the temporal pattern sensitivity of the nerve cells, and the average response entropy per symbol as a measure for the frequency transfer characteristics. To use these measures, the probability of a post-synaptic spike as a function of the recent history of pre-synaptic intervals was examined in detail. As the results of such application, it was found that the EPSP size is closely related to the pattern of impulse sequences of the input, and the average mutual information per symbol for EPSP size is given by a bimodal curve with two maximum values. One is a small EPSP size and the other is a large EPSP size. In two maximum points, the structure of the temporal pattern discrimination reverses each other. In addition, the relation between the mean frequency, or the form of impulse sequences of the input, and the average mutual information per symbol has been examined. The EPSP size at one maximum point of average mutual information is in inverse proportion to the magnitude of input mean frequency which relates to the convergence number of input terminal, while that at the other maximum point is proportional to that of the mean frequency. Moreover, the temporal pattern discrimination is affected remarkably by whether successive interspike intervals of the input are independent or not in the statistical sense. Computer experiments were performed by the semi-Markov processes with three typical types of transition matrixes and these shuffling processes. The average mutual informations in the cases of these semi-Markov processes are in contrast to those of the shuffling processes which provide a control case. The temporal structure of successive interspike intervals of the input is thus a significant factor in pattern discrimination at synaptic level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326706
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  • 9
    Electronic Resource
    Electronic Resource
    The stochastic properties of the basic neuron populations as information processing system (1978)
    Springer
    Biological cybernetics 29 (1978), S. 167-173 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract This paper deals with the stochastic properties of the simplest neuron population consists of two neurons. Two modes of neural coupling are discussed. One is the forward inhibition mode [FI] and the other is the backward inhibition mode [BI]. In the forward inhibition mode, the two neurons are assumed to be independent of each other. In the backward inhibition mode, the two neurons interact, but the inputs to the neurons are assumed to be independent of each other. In the analysis, we first obtain the probability density function [p.d.f.] of the interspike intervals of the output impulse trains in FI and BI. Then we define the mean rate transfer function from the mean rate of these p.d.f.'s. Finally, by comparing our analytical results with the physiological experimental data, it is clear that the difference in the stochastic properties can be accounted for by the difference in the coupling mode (i.e. FI or BI).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337353
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  • 10
    Electronic Resource
    Electronic Resource
    Stochastic automaton models for the temporal pattern discrimination of nerve impulse sequences (1976)
    Springer
    Biological cybernetics 21 (1976), S. 121-130 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The application of stochastic automata to the input-output relations of single neurons is considered. For this, some stochastic properties of temporal pattern discrimination in single synaptic cells are used to suggest stochastic automaton models. The models have only three possible states, the active, the absolute refractory and the relative refractory states, which are sufficient for temporal pattern sensitivity. From such an application, it was found that the temporal pattern discriminating structures in the models are similar to those used for experimental data and computer simulation (real-time neuron models). Extensions related to temporal pattern learning are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337419
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