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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of conservative and rotational forms in large eddy simulation of turbulent channel flow
    Amsterdam : Elsevier
    Journal of Computational Physics 71 (1987), S. 343-370 
    Details
    ISSN: 0021-9991
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Computer Science , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0021-9991(87)90035-0
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  • 2
    Electronic Resource
    Electronic Resource
    Ca-induced Ca release in the sarcoplasmic reticulum of cardiac muscle of the guinea pig
    Amsterdam : Elsevier
    Journal of Molecular and Cellular Cardiology 18 (1986), S. 38 
    Details
    ISSN: 0022-2828
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0022-2828(86)80593-4
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  • 3
    Electronic Resource
    Electronic Resource
    Small-Angle X-ray Diffraction of Muscle Using Undulator Radiation from the Tristan Main Ring at KEK (1996)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 3 (1996), S. 305-312 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Time-resolved X-ray diffraction of muscle has demanded ever-increasing flux into small sample volumes with low beam divergence. Results are reported of static and time-resolved small-angle X-ray diffraction studies on muscle fibers using a hard X-ray undulator installed in the Tristan main ring at KEK, Tsukuba, Japan, as an innovative source of synchrotron radiation more intense and better collimated than that available with the Photon Factory bending-magnet beamline. Static studies used the low divergence of the source to obtain detailed high-quality diffraction patterns of stable muscle states. The diffraction patterns from live skeletal muscles showed the numerous (over 100) meridional reflections. The well collimated beam from the undulator made it possible to clearly resolve, with an angular resolution of ca 700 nm, the closely spaced diffraction peaks arising from the two halves of the thick filaments centred on the M lines in a sarcomere, in addition, the diffraction peaks from the thin filaments on opposite sides of the Z bands could be resolved with an angular resolution of ca 1000 nm. The detailed structure of the meridional pattern defines the nature of the molecular packing in the thick and thin filaments. Time-resolved experiments using a focusing mirror aimed to prove cross-bridge states in striated muscle fibers by collecting X-ray diffraction data at a 0.185 ms time resolution from sinusoidally oscillating chemically skinned rabbit muscle fibers during active contraction and in rigor. When sinusoidal length changes at 500 Hz with a peak-to-peak amplitude of 0.6% of the muscle length were applied to a small fiber bundle, the tension showed a simple elastic response during the length oscillation. In the active muscle the intensity of the 14.5 nm myosin-based meridional reflection changed out of phase with the tension change during the oscillating length change. In contrast, in the rigor muscle it occurred in phase with the tension change. The high time-resolved experiments provide an insight into the coupling between conformational changes and force generation of the actomyosin cross-bridges. These studies provide a preview of the expected gains for muscle studies from the more widespread use of undulator radiation at third-generation synchrotron sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049596008928
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanical response to photolytic ATP pulses of skinned muscle fibres pre-activated with a small pulse of ATP (1993)
    Springer
    Journal of muscle research and cell motility 14 (1993), S. 335-340 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary (1) Skinned fibres from rat psoas muscle were placed in oil and activated at 10°C by pulse photolysis of caged ATP. From the force and stiffness transients on small ATP pulses, we estimated the concentration and rate of ATP hydrolysis of the crossbridges in the fibres. They were 0.14 mM and 0.16 mM s-1, respectively, and thus the turnover rate was 1.1 s-1. (2) To examine the mechanical properties of the physiological ADP-bound crossbridges, we took a double-pulse protocol: the skinned fibre was first activated with a conditioning ATP pulse (0.2–0.5 mM). Several (3–5) seconds later, when almost all the ATP should have been hydrolysed into ADP+Pi, we applied another ATP pulse (0.2–1 mM) to test the fibre. (3) An analysis of the transients on the test pulses indicated that the conditioning pulse slowed the rate of crossbridge detachment. The time course of force development was thus expected to be also delayed, but was not. (4) We suggested that the rigor crossbridge might differ from the nucleotide-free intermediate in the physiological reaction cycle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123098
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of 2,3-butanedione monoxime on contraction of frog skeletal muscles: An X-ray diffraction study (1992)
    Springer
    Journal of muscle research and cell motility 13 (1992), S. 153-160 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We studied the effects of BDM (2,3-butanedione monoxime) on the tetanic contraction of frog skeletal muscles using an X-ray diffraction technique. BDM significantly increased the resting equatorial intensity ratio (I 1,0/I 1,1). In sartorius muscle, 3mm BDM suppressed tetanic tension by 40–70% whereas the equatorial intensity ratio, which is 2.6 at rest, decreased to 0.75 during tetanus, close to the value in normal contraction (about 0.50). BDM (3mm) reduced the intensity increase of the 5.1-nm layer-line to 41%, that of the 5.9-nm layer-line to 24%, and the intensity decrease of the second myosin meridional reflection (at 1/21.5 nm−1) at 81%. In overstretched semitendinosus muscle, 3mm BDM did not significantly reduce the intensity increase of the second actin layer-line during activation, suggesting that enough calcium is released to activate the regulatory system and the regulatory proteins are intact. These results indicate that BDM suppresses tetanic tension by mainly inhibiting actin-myosin interaction. It has a smaller effect on the equatorial reflections and myosin layer-lines than on the actin layer-lines, suggesting that BDM-influenced myosin heads may bind to actin without following the symmetry of the actin helix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01874152
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of ethylene glycol on the kinetics of contraction on flash photolysis of caged ATP in rat psoas muscle fibres (1992)
    Springer
    Journal of muscle research and cell motility 13 (1992), S. 199-205 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary ATP (1–1.2mm) was photoreleased from caged ATP (5mm) in skinned fibres from rat psoas muscle at 15–17° C, to examine the effects of ethylene glycol (EG; 20% in solvent) on the kinetics of isometric contraction. Muscle fibres were stretched by 0.5–2% before photolysis, so that force just before photolysis was almost equal to the steady-state force after photolysis. At the phase of steady-state contraction, force and 500 Hz-stifmess in the presence of EG were 50% and 70% of the controls, respectively, resulting in a higher stiffness-to-force with EG, as reported previously. Following photolysis, force fell before rising to a steady-state plateau. The estimated rate constant of the force decay was approximately 90 s−1, and in the presence of EG was 80–85% of the control. This suggested a small effect of EG on the crossbridge detachment induced by ATP. The rate of force redevelopment was approximately 70 s−1, and EG decreased this rate to 50% of the control. This suggested that EG greatly slows the transition of the crossbridges from the detached state to the reattached force-producing state. The time course of the stiffness signals was consistent with this interpretation. The high stiffness-to-force ratio with EG indicated that EG not only reduces the rate constants which were directly examined in this study but also modifies other aspects of the crossbridge reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01874157
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of ADP and low ATP on the Ca2+-sensitive transient contraction upon photolysis of caged ATPin rat muscle fibres: a study on the Bremel–Webertype cooperation (1998)
    Springer
    Journal of muscle research and cell motility 19 (1998), S. 923-930 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Caged ATP was photolysed in rat psoas fibres under various conditions to examine whether ADP plays a special role in the␣‘Bremel–Weber type cooperation’, viz. the Ca2+-like action of the rigor cross-bridges. Various concentrations of ATP (0.25–1.6mm) were photoreleased in the presence of various concentrations of ADP (0–0.4mm) at ∼8 or 20°C. The Ca2+ concentration was set at around 0.2μm in order that the ATP-induced contraction was significant but short. Both lower [ATP] and higher [ADP] resulted in a slower detachment of the rigor cross-bridges and a larger contraction after the detachment. ADP did not seem to affect the relationship between the rate of detachment and the size of the Ca2+-sensitive component of the subsequent contraction. It is concluded that there is little evidence that the ADP-bound rigor cross-bridges are more potent than the nucleotide-free ones in the Bremel–Weber type cooperation that is seen in the ATP-induced transient contraction. The mechanism by which the ADP-specific, Ca2+-independent contraction occurs immediately after the release of ATP remains to be clarified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005408300024
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of ethylene glycol and calcium on the kinetics of contraction induced by photo-release of low concentrations of ATP in rat psoas muscle fibres (1992)
    Springer
    Journal of muscle research and cell motility 13 (1992), S. 464-472 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To induce isometric contraction in the absence of Ca2+ (10mm EGTA), low concentrations (130 μM) of ATP were photoreleased from caged ATP in skinned fibres from rat psoas muscle at 15–16° C. The magnitude of contraction was independent of the concentration of EGTA (1–30mm). Each isometric transient (i) was paired with another (s) obtained under the same conditions but with 0.4% muscle stretch to elevate the rigor force before photolysis. The algebraic difference (d) betweeni ands was assumed to represent detachment of the crossbridges. The time course of force development (f) by the reattached crossbridges could be estimated by subtracting an appropriately scaledd fromi (ors). Ethylene glycol (20% in solvent) reduced the magnitude and the rate of rise off, although it scarcely affectedd, suggesting that ethylene glycol inhibited reattachment of the crossbridges but not their detachment. The presence of Ca2+ (50 μM) increased the magnitude off, but did not affect its time course (130 μM ATP). Detachment,d, was not influenced by Ca2+ in terms of both extent and rate. The effect of Ca2+ in the presence of ethylene glycol was indistinguishable from that in its absence. Ethylene glycol did not seem to substantially affect the extent of Ca-regulation on the contractile activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01738041
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  • 9
    Electronic Resource
    Electronic Resource
    Time course of rise of muscle stiffness at onset of contraction induced by photorelease of ATP (1992)
    Springer
    Journal of muscle research and cell motility 13 (1992), S. 685-691 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Isometric contraction (9–10°C) of skinned fibres from rat psoas muscle was elicited by photorelease of ATP (1.3–1.4 mM), and force (F), in-phase (I) and quadrature (Q) stiffness were monitored. The sinusoidal length change for the stiffness measurement was ≈ 0.09% fibre length and 200–1000 Hz. On photolysis,F andI initially fell, and then rose. The half-time of the rise ofI was shorter than that ofF. Contrary to the previous assumption,Q rose even earlier thanI. Although the time courses of the rise ofF andI were greatly affected by the presence of phosphate ion (Pi; 4 mM), its effect onQ was modest. We propose the following hypothesis: the rigor crossbridges, after binding ATP, initially enter a state characterized by highQ with lowI and none or littleF, and then, releasing Pi during passing the state with the increasedI, reach the final force generating state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01738257
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanism of action of 2, 3-butanedione 2-monoxime on contraction of frog skeletal muscle fibres (1988)
    Springer
    Journal of muscle research and cell motility 9 (1988), S. 156-164 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mechanism of the inhibitory effect of 2, 3-butanedione 2-monoxime (BDM) on contraction of frog skeletal muscles was studied using skinned fibres and aequorin-injected intact fibres. The tension development of skinned fibres directly activated with calcium was strongly inhibited by BDM. This agent also had effects on the sarcoplasmic reticulum in the skinned preparations, suppressing the calcium pump function and enhancing the activity of the ‘calcium-induced calcium release’ mechanism. In electrically stimulated intact fibres, although BDM slightly suppressed the elevation of the intracellular calcium ion concentration, this effect was so weak that it would not explain the strong inhibitory effect of the agent on the tension development by the intact fibres. It was concluded that the tension reducing effect of BDM on intact fibres was due mainly to its direct action on the contractile system. The mode of this action of BDM was further examined with skinned fibres in view of its effects on the maximum shortening speed and isometric tension in low MgATP environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01773737
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