Pier Giovanni Bracchi

Postnatal development of the M-band in rat cardiac myofibrils.

Cardiac muscle fibers in rats at 1 and 5 days after birth showed little evidence of Mbands. An ultrastructural analysis of myofibrils failed to demonstrate dense M-band material in longitudinal sections or M-bridges in transverse sections of sarcomeres. M-bands began to increase in number after 5 days of postnatal life and were present in 60% of all sarcomeres at 11 days of age. Polypeptides with molecular weights of 190,000 (M«) and 175,000 (Mb) were obtained by polyacrylamide-sodium dodecyl sulfate (SDS) gel electrophoresis of myofibril preparations. These two proteins were found in both 1-and 11-day-old rats and were considered to be specific components of the M-band. The densitometric analysis demonstrated that M. and Mb polypeptides increased approximately 2-fold during the interval from 1 to 11 days after birth. These structural and biochemical changes of the M-band material in myocytes appear to be related to the maturation of contractile function in the young heart. Circ Res 48: 561-568, 1981

Biochemical Correlations During the Senile Opacification of the Human Lens

The levels of Na+, K+, Ca++, ribonuclease activity, soluble and insoluble proteins have been determined in unselected senile cataractous human lenses and in non-catara

Physically-based simulation of the spine in dog walking

Biomechanics has strong implications in both medicine and robotics as it is concerned with the study of biological systems from an engineering point of view. In this work we propose a physics-based system for accurate simulation of dogpsilas spine at walking gait. The spinal column has been modeled as a set of rigid bodies, representing the vertebrae, connected by joints. Real-time dynamic simulation has been carried out from motion captured data collected from skin markers. A feedback controller has been developed for error minimization. The main contribution of the paper is the development of a tool for analyzing the forces acting on the spine. We report experiments performed with a boxer dog walking on a treadmill. Potential applications of this study involve bio-inspired robotics and computer graphics, as well as diagnostic applications for live animals.