Steven R. Smith
University of California
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Featured researches published by Steven R. Smith.
Advances in Experimental Medicine and Biology | 2000
Miklós Kellermayer; Steven R. Smith; Carlos Bustamante; Henk Granzier
Titin (also known as connectin) is a giant filamentous polypeptide of multi-domain construction spanning between the Z- and M-lines of the vertebrate muscle sarcomere. The molecule is significant in maintaining sarcomeric structural integrity and generating passive muscle force via its elastic properties. Here we summarize our efforts to characterize titins elastic properties by manipulating single molecules with force-measuring laser tweezers. The titin molecules can be described as an entropic spring in which domain unfolding occurs at high forces during stretch and refolding at low forces during release. Statistical analysis of a large number (> 500) of stretch-release experiments and comparison of experimental data with the predictions of the wormlike chain theory permit the estimation of unfolded titins mean persistence length as 16.86 A (+/- 0.11 SD). The slow rates of unfolding and refolding compared with the rates of stretch and release, respectively, result in a state of non-equilibrium and the display of force hysteresis. Folding kinetics as the source of non-equilibrium is directly demonstrated here by the abolishment of force hysteresis in the presence of chemical denaturant. Experimental observations were well simulated by superimposing a simple domain folding kinetics model on the wormlike chain behavior of titin and considering the characteristics of the compliant laser trap. The original video presentation of this paper may be viewed on the web at http:¿www.pote.hu/mm/prezentacio/mkpres/++ +mkpres.htm.
Archive | 2009
Steven R. Smith; Jessica A. Little; Lisa A. Nowinski; Sara J. Walker
Although rating scales and checklists are useful and informative for some clinical situations and settings, there are times when a more comprehensive psychological or neuropsychological assessment is called for. The present chapter outlines the different forms of psychological assessment and how a more comprehensive assessment might lead to improved diagnosis and treatment. Furthermore, the use of psychological assessment as a therapeutic intervention will also be addressed and explained. Finally, the specifics of how to ask a good referral question that might result in a beneficial assessment will be discussed.
Archive | 2002
Miklós Kellermayer; Steven R. Smith; Carlos Bustamante; Henk Granzier
A polymer strand can be influenced by an array of mechanical effects as it translates through a space with dimensions similar to its own. We summarize our experiments in which the mechanical behavior of single-molecules of the giant protein titin was characterized. Titin is a filamentous polypeptide embedded in the lattice space of the vertebrate muscle sarcomere. A single titin molecule stretches from the Z- to the M-line of the sarcomere, thereby spanning a distance of approximately 1 μm which is huge on the molecular scale. Physiologically, titin is important in generating passive muscle force and in maintaining the structural integrity of the sarcomere through its elastic properties. We analyzed the elastic properties of titin by stretching single molecules with laser tweezers. The force-response of the titin molecule revealed an entropic polymer whose behaviour can be well fitted with the wormlike chain model. Unfolding occurs in titin upon reaching high forces during stretch, and refolding takes place at low forces during the relaxation of the molecule. The force hysteresis implies folding non-equilibrium due to the slow unfolding and refolding rates relative to the stretch and release rates, respectively. Folding non-equilibrium as the source of force hysteresis can be demonstrated by the disappearance of hysteresis upon the addition of chemical denaturant. Repeated stretch and release cycles lead to the mechanical wear-out or fatigue of titin, which may have far-reaching implications for its physiological function.
Archive | 2008
Tad T. Gorske; Steven R. Smith
Current Psychology | 2017
Aaron R. Estrada; Steven R. Smith
Archive | 2009
Steven R. Smith; Tad T. Gorske
Archive | 2009
Tad T. Gorske; Steven R. Smith
Archive | 2009
Tad T. Gorske; Steven R. Smith
Archive | 2008
Tad T. Gorske; Steven R. Smith
Archive | 2008
Tad T. Gorske; Steven R. Smith