Day 1 :
University of Washington, USA
Time : 10:00-10:45
Minoru Taya is currently Director, Center for Intelligent Materials and Systems, and also Nabtesco Endowed Chair Professor of Mechanical Engineering in University of Washington. Dr. Minoru Taya obtained his BS in Engineering in 1968 from University of Tokyo, and his MS in 1973 and PhD 1977 in Theoretical Applied Mechanics from Northwestern University. Dr. Taya involved in supervising a number of projects related to multifunctional materials and composites with emphasis on sensing and active materials, and compact actuators Most recently, we is working on (i) FePd nanohelix based nanorobotics under NSF-NRI program where the FePd nanohelix can shrink and expand upon switching on and off magnetic field and (ii) soft-matter based robotic hand technology using dielectric elastomer. Dr. Taya has published over 330 papers, 5 book chapters in the area of intelligent materials and systems and composites and 7 books. In addition, he published the three monograph books.
Recently, we successfully processed the FePd nanorobots (NRs) by using electrochemistry route and post annealing process. The actuation mechanism of the proposed FePd NRs is based on two scientific mechanisms associated with ferromagnetic shape memory alloy Fe70Pd30; (i) hybrid mechanism of chain reaction events; applied magnetic field gradient, magnetic force, stress-induced martensite phase transformation of Fe70Pd30 from stiff austenite to soft martensite, resulting in larger displacement at very high speed that we discovered and (ii) magnetic interactions coupled with stress-induced martensite phase transformation under constant magnetic field, resulting in large displacement. This phase transformation of FePd nanohelix is considered different from that of its bulk sized FePd. It is found that the martensite start temperature(Ms) of the FePd nano-material is shifted toward lower temperature as compared with that Ms of the bulk sized FeP and also the FePd nanohelix NR can exhibits nano-motions under applied constant magnetic field. There are many applications we can apply the above FePd NRs, one of which is a new treatment of cancers by applying mechanical stress loading on live cancers, inducing mechanical stress induced cell death (MSICD) on target cancer cells. We performed a biocompatibility testing on Fe7Pd3 nanoparticles to find that the use of modest amount of the FePd nanoactuators would NOT be cytotoxic to BT-474 breast cancer cells. Here we report some preliminary results of in vitro experiment of MSICD using macroscopic mechanical loading set up which apply mainly dynamic compression loading to live target cells via agarose gel layer. The preliminary results of MSIC indicate that the live breast cancer cells under dominant compressive stress loading area exhibit a mixture of apoptosis and necrosis cell death modes while those under dominant shear stress loading area shows strongly necrosis cell mode
Department of Physiology, Teikyo University School of Medicine, Tokyo, Japan
Keynote: Myosin head power stroke does not obey predictions based on the swinging lever arm mechanism of muscle contraction
Time : 10:45-11:30
Haruo Sugi graduated from post-graduated school in the University of Tokyo with the degree of PhD in 1962, and was appointed to be an Instructor in Physiology, in the University of Tokyo Medical School. From 1965 to 1967, he worked at Columbia University as research associate, and at the National Instututes of Health as a visiting scientist. Sugi was Professor and Chairman in Teikyo University Medical School from 1973 to 2004 when he became Emeritus Professor. He was Chairman of Muscle Commission in the International Union of Physiological Sciences from 1998 to 2008 (IUPS). He organized Symposia on molecular mechanism of muscle contraction six times, each followed by Proceeding published from University of Tokyo Press, Plenum, Kluwer and Springer and regarded as milestones of progress in this area of research work.
Although more than 50 years have passed since the monumental discovery of sliding filament mechanism in muscle contraction, the molecular mechanism of myosin head movement, coupled with ATP hydrolysis, is still a matter for debate and speculation. A most straightforward way to study myosin head movement, producing myofilament sliding, may be to directly record ATP-induced myosin head movement in hydrated, living myosin filaments using the gas environmental chamber (EC) attached to an electron microscope . While the EC has long been used by materials scientists for the in situ observation of chemical reaction of inorganic compounds, we are the only group successfully using the EC to record myosin head movement in living myosin filaments. We position-mark individual myosin heads by attaching gold particles (diameter, 20nm) via three different monoclonal antibodies, attaching to (1) at the distal region of myosin head catalytic domain (CAD), (2) at the myosin head converter domain(COD), and (3) at the myosin head lever arm domain(LD). First, we recoded ATP-induced myosin head movement in the absence of actin filaments, and found that myosin heads moved away from, but not towards, the central bare region of myosin filaments. We also succeeded in recording ATP-induced myosin head power stroke in actin-myosin filament mixture. Since only a limited proportion of myosin heads can be activated by a limited amount of ATP applied, myosin heads only move by stretching adjacent sarcomere structures. As shown in Fig.1, myosin head CAD did not move parallel to the filament axis in the standard ionic strength (B), while it moved parallel to the filament axis (C). These results indicate that myosin head movement does not necessarily obey predictions of the swinging lever arm hypothesis appearing in every text books as an established fact.