Photofragmentation reactions of dithiolactones

The occurrence of Norrish type-I \alpha-cleavage has been established in \beta-dithiofactones, involving the $n-\pi^*$ singlet state (diradical and carbene reactive intermediates). Concerted ring expansion to a thiacarbene from the excited state is suggested to be responsible for the formation, at least in part, of one of the cyclic thioacetals. Although this \alpha-cleavage process is similar to that of corresponding \beta-lactones, the hehaviour of the resulting intermediates is different

A perspective on digital and computational pathology

The digitization of images has not only led to increasingly sophisticated methods of quantitating information from those images themselves, but also to the development of new physics-based techniques for extracting information from the original specimen and presenting this as visual data in both two and three-dimensional (3D) forms. This evolution of an image-based discipline has reached maturity in Radiology, but it is only just beginning in Pathology. An historical perspective is provided both on the current state of computational imaging in pathology and of the factors that are impeding further progress in the development and application of these approaches. Emphasis is placed on barriers to the dissemination of information in this area. The value of computational imaging in basic and translational research is clear. However, while there are many examples of "virtual diagnostics" in Radiology, there are only relatively few in Pathology. Nevertheless, we can do cellular level analysis of lesions accessible by endoscopic or catheterization procedures, and a number of steps have been taken toward real-time imaging as adjuncts to traditional biopsies. Progress in computational imaging will greatly expand the role of pathologists in clinical medicine as well as research

Effects of aging on regulation of muscle contraction at the motor unit, muscle cell, and molecular levels

Etude des mécanismes intervenant dans l'augmentation des risques de chutes chez les personnes âgées, notamment au niveau du système nerveux central et périphérique, et au coeur du tissu musculaire

Full-length myosin VI dimerizes and moves processively along actin filaments upon monomer clustering

Summary Myosin VI is a reverse direction actin-based motor capable of taking large steps (30-36 nm) when dimerized. However, all dimeric myosin VI molecules so far examined have included nonnative coiled-coil sequences, and reports on full-length myosin VI have failed to demonstrate the existence of dimers. Herein, we demonstrate that full-length myosin VI is capable of forming stable, processive dimers when monomers are clustered, which move up to 1-2 mm in w30 nm, handover-hand steps. Furthermore, we present data consistent with the monomers being prevented from dimerizing unless they are held in close proximity and that dimerization is somewhat inhibited by the cargo binding tail. A model thus emerges that cargo binding likely clusters and initiates dimerization of full-length myosin VI molecules. Although this mechanism has not been previously described for members of the myosin superfamily, it is somewhat analogous to the proposed mechanism of dimerization for the kinesin Unc104