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Distribution Of Myosin Attachment Times Predicted From Viscoelasticmechanics Of Striatedmuscle, Bradley M. Palmer, Yuan Wang, Mark S. Miller
Distribution Of Myosin Attachment Times Predicted From Viscoelasticmechanics Of Striatedmuscle, Bradley M. Palmer, Yuan Wang, Mark S. Miller
Mark S. Miller
We demonstrate that viscoelastic mechanics of striated muscle, measured as elastic and viscous moduli, emerge directly from the myosin crossbridge attachment time, tatt, also called time-on. The distribution of tatt was modeled using a gamma distribution with shape parameter, p, and scale parameter, β. At 5mM MgATP, β was similar between mouse α-MyHC (16.0 ± 3.7ms) and β-MyHC (17.9 ± 2.0ms), and p was higher (P < 0.05) for β-MyHC (5.6 ± 0.4 no units) compared to α-MyHC (3.2 ± 0.9). At 1mMMgATP, p approached a value of 10 in both isoforms, but β rose only in the β-MyHC (34.8 ± 5.8ms). The estimated mean tatt (i.e., pβ product) was longer in the β-MyHC compared to α-MyHC, and became prolonged in both isoforms as MgATP was reduced as expected. The application of our viscoelastic model to these isoforms and varying MgATP conditions suggest that tatt is better modeled as a gamma distribution due to its representing multiple temporal events occurring within tatt compared to a single exponential distribution which assumes only one temporal event within tatt.
Effect Of Resistance Training On Physical Disability In Chronic Heart Failure, Patrick Savage, Anthony O. Shaw, Mark S. Miller, Peter Vanburen, Martin M. Lewinter, Philip A. Ades, Michael J. Toth
Effect Of Resistance Training On Physical Disability In Chronic Heart Failure, Patrick Savage, Anthony O. Shaw, Mark S. Miller, Peter Vanburen, Martin M. Lewinter, Philip A. Ades, Michael J. Toth
Mark S. Miller
Purpose—Patients with chronic heart failure (CHF) report difficulty performing activities of daily living. To our knowledge, however, no study has directly measured performance in activities of daily living in these patients to systematically assess their level of physical disability. Moreover, the contribution of skeletal muscle weakness to physical disability in CHF remains unclear. Thus, we measured performance in activities of daily living in CHF patients and controls, its relationship to aerobic capacity and muscle strength and the effect of resistance exercise training to improve muscle strength and physical disability. Methods—Patients and controls were assessed for performance in activities of daily …
Cooh-Terminal Truncation Of Flightin Decreases Myofilament Lattice Organization, Cross-Bridge Binding, And Power Output Indrosophila Indirect Flight Muscle, Bertrand C.W. Tanner, Mark S. Miller, Becky M. Miller, Panagiotis Lekkas, Thomas C. Irving, David W. Maughan, Jim O. Vigoreaux
Cooh-Terminal Truncation Of Flightin Decreases Myofilament Lattice Organization, Cross-Bridge Binding, And Power Output Indrosophila Indirect Flight Muscle, Bertrand C.W. Tanner, Mark S. Miller, Becky M. Miller, Panagiotis Lekkas, Thomas C. Irving, David W. Maughan, Jim O. Vigoreaux
Mark S. Miller
IN MUSCLE, THE THICK AND THIN filament lattice provides the structural and mechanical foundation for transmitting contractile forces throughout the cell. The highly ordered indirect flight muscle (IFM) of Drosophila melanogaster is an attractive model system to study the relationship between lattice structure and muscle function, because its in vivo lattice organization can be measured via X-ray diffraction in living flies (15) and its function can be measured from the whole fly to the molecule (14, 20, 30). In addition, the means for producing genetic alterations of specific proteins in D. melanogaster are well established, permitting precise manipulation of thick …
Regulatory Light Chain Phosphorylation And N-Terminal Extension Increase Cross-Bridge Binding And Power Output In Drosophila At In Vivo Myofilament Lattice Spacing, Mark S. Miller, Gerrie P. Farman, Joan M. Braddock, Felipe N. Soto-Adames, Thomas C. Ivring, Jim O. Vigoreaux, David W. Maughan
Regulatory Light Chain Phosphorylation And N-Terminal Extension Increase Cross-Bridge Binding And Power Output In Drosophila At In Vivo Myofilament Lattice Spacing, Mark S. Miller, Gerrie P. Farman, Joan M. Braddock, Felipe N. Soto-Adames, Thomas C. Ivring, Jim O. Vigoreaux, David W. Maughan
Mark S. Miller
The N-terminal extension and phosphorylation of the myosin regulatory light chain (RLC) independently improve Drosophila melanogaster flight performance. Here we examine the functional and structural role of the RLC in chemically skinned fibers at various thick and thin filament lattice spacings from four transgenic Drosophila lines: rescued null or control (Dmlc2þ), truncated N-terminal extension (Dmlc2D2-46), disrupted myosin light chain kinase phosphorylation sites (Dmlc2S66A,S67A), and dual mutant (Dmlc2D2-46; S66A,S67A). The N-terminal extension truncation and phosphorylation sites disruption mutations decreased oscillatory power output and the frequency of maximum power output in maximally Ca2+-activated fibers compressed to near in vivo inter-thick filament spacing, …