Contraction mechanisms

TAKAHASHI M, MORIGUCHI S, IKENO M, KONO S, OHATA K., USUI H, KURAHASHI K, SASAKI R, YOSHIKAWA M (1996) Studies on the Ueum-contracting mechanisms and identification as a complement C3a receptor agonist of oryzatensin, a bioactive peptide derived from rice albumin. Peptides. 17 5-12. 

Finding 7. The procurement strategy proposed for closure of the JACADS facility appears to be workable however, the contracting mechanism is awkward and inherently inefficient. 

Examines the muscle-contraction mechanism from a structural perspective. 

Removal of free cytosolic calcium If free cytosolic calcium levels were to remain high, the cardiac muscle would be in a constant state of contraction, rather than showing a periodic contraction. Mechanisms of removal include two alternatives. 

In phase 3 of cellular respiration, the high-energy phosphate bonds of ATP are used for processes such as muscle contraction (mechanical work), maintaining low intracellular Na concentrations (transport work), synthesis of larger molecules such as DNA in anabolic pathways (biosynthetic work), or detoxification (biochemical work). As a consequence of these processes, ATP is either directly or indirectly hydrolyzed to ADP and inorganic phosphate (Pi), or to AMP and pyrophosphate (PPi). 

Mechanisms of contraction for mesenchymal cells may be more dependent on formation of stress fibers and focal contacts than on the cortical contraction mechanisms seen in Dictyostelium [195]. Receptor tyrosine kinases can stimulate increased myosin light chain phosphorylation via rho activation as a mechanism for contraction. Alternatively, increased contraction may follow formation of new focal contacts, possibly via focal adhesion kinase and src-based mechanisms [212]. This would be consistent with the temporal sequence of events that are observed, with contraction being a late step that should follow formation of new focal contacts. 

Palladino, J.L. and Noordergraaf, A. 1998. Muscle contraction mechanics from ultrastructural dynamics. In Analysis and Assessment of Cardiovascular Function, G.M. Drzewiecki and J.K.-J. Li, Eds., Springer-Verlag, New York, chap. 3, pp. 53-57. 

Brandt, P.W., Colomo, R, Poggesi, C., and Tesi, C. 1993. Taking the first steps in contraction mechanics of single myocytes from frog heart. In Mechanism of Myofilament Sliding in Muscle Contraction, H. Sugi and G.H. Pollack, Eds., Plenum Press, NY. 

EXHIBIT 10.15 Breakdown of Repo Volumes by Contract Mechanism... 

Jin, M. and S. D. Wu. 2001a. Supply chain coordination in electronic markets Auction and contracting mechanisms. Working Paper. Lehigh University, Bethlehem, PA. 

Two mechanisms are often used to describe physical aging lattice contraction and diffusion of free volume. In the lattice-contraction mechanism, the polymer chains are pictured as imiformly moving closer together, as if the lattice spacing throughout the pol5uner has decreased. The kinetics of the lattice contraction are not dependent on the sample dimensions. The diffusion of free volume or holes was first proposed by Alfrey (134). In this mechanism, packets of free-volume are pictured as diffusing from the interior to the surface of the sample where they are eliminated. Since the diffusion of free-volume process is assmned to be Fickian, the loss of free volume becomes dependent on the sample dimensions. 

The dual-mechanism approach of McCaig and co-workers described above was able to describe the oxygen permeability decay in bisphenol. A benzophenone-dicarboxylic acid (BPA-BnzDCA) films of varying thickness remarkably well. This data is illustrated in Figure 35. All films, regardless of thickness, experience an initial sharp decline in permeability. This drop is due to the lattice-contraction mechanism, which is independent of sample dimension. Only in the thin films where the half-thickness i was less than 2.5 /u,m was a contribution from the free-volume diffusion mechanism observed. 

The energy utilization by the cardiac muscle is a complex process which is strongly affected by metabolic and mechanical parameters. The cardiac muscle derives almost all of its energy supply by aerobic metabolism and is thus highly dependent on the oxygen supply. Short cessations of the oxygen supply to the contracting tissues will affect the contraction mechanics within a few seconds. 

Although there are no positive Indications that structured water plays a role in the mechanism of muscle contraction, a theoretical mechanism employing the Ice lattice can be devised. Such a scheme uses protein-water interactions In two phases Involving Interchanging enol and keto forms of the peptide carbonyls, and was first mentioned as a possible contraction mechanism In an Informal discussion A coiq>lete elaboration of this concept as a model for muscle contraction has been publlshed. This model, which employs water In an active structural and mechanical sense, may be relevant to the earlier observation of Goodall that proton transfer could be the rate-determining step in muscle contraction. Home and Johnson have shown that variables such as pressure, ten erature, and Isotope (D2O) may Influence proton transfer In the aqueous environment, and each of these variables has been shown to have an effect on muscle contraction. 

The proposed utility of the hexagonal concept of protein conformation in a muscle contraction mechanism has already been noted S. With the large... 

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