Calcium-Dependent Translocation of S100B Is Facilitated by Neurocalcin Delta

S100B is a calcium-binding protein that governs calcium-mediated responses in a variety of cells—especially neuronal and glial cells. It is also extensively investigated as a potential biomarker for several disease conditions, especially neurodegenerative ones. In order to establish S100B as a viable pharmaceutical target, it is critical to understand its mechanistic role in signaling pathways and its interacting partners. In this report, we provide evidence to support a calcium-regulated interaction between S100B and the neuronal calcium sensor protein, neurocalcin delta both in vitro and in living cells. Membrane overlay assays were used to test the interaction between purified proteins in vitro and bimolecular fluorescence complementation assays, for interactions in living cells. Added calcium is essential for interaction in vitro; however, in living cells, calcium elevation causes translocation of the NCALD-S100B complex to the membrane-rich, perinuclear trans-Golgi network in COS7 cells, suggesting that the response is independent of specialized structures/molecules found in neuronal/glial cells. Similar results are also observed with hippocalcin, a closely related paralog; however, the interaction appears less robust in vitro. The N-terminal region of NCALD and HPCA appear to be critical for interaction with S100B based on in vitro experiments. The possible physiological significance of this interaction is discussed.     

Generic crack patterns in rubber‐modified polymers under biaxial stress states

The damage mechanisms in three different systems, namely, acrylonitrile‐butadiene‐styrene, methacrylate‐butadiene‐styrene modified poly(vinyl chloride), and styrene‐butadiene‐styrene have been investigated. The damage was analyzed over a range of biaxial stress states with confocal microscopy and scanning electron microscopy. The macroscopic yield followed a linear behavior for all the systems in an octahedral shear stress versus mean stress plot, whereas popular models for this class of materials predicted a nonlinear response. Over a certain range of biaxial stress states, a damage pattern generic to all the systems was observed. The damage pattern consisted of an array of cracks propagating perpendicular to the direction of the maximum tensile principal stress and arranged itself in a more or less periodic fashion. There was also self‐similarity in the patterns at various length scales. Similar patterns have also occurred in several other polymeric systems. The interaction in the ensemble of cracks created seems to lead to stress reduction at the crack tips, thereby limiting the crack sizes. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2248–2256, 2003     

Classical methods in molecular scattering: a continuous quantization procedure

A simple improvement of the quasiclassical histogram approximation in molecular scattering is presented, based on a continuity ansatz that relates arbitrary classical actions and non-stationary quantum states. This procedure is applied to the case of collinear collisions in atom—harmonic oscillator systems and increases the accuracy of standard quasiclassical methods     

Harmonic generation in an electromagnetic wave

A plane electromagnetic wave is propagated in a non-linear non-dissipative isotropic dielectric. A method is given for the calculation of the change in the amplitudes and phases of harmonics of all orders, as the wave progresses, for any specified dependence of the dielectric constant on the magnitude of the electric field and for any initial wave form. The calculations are valid provided the distance of travel is sufficiently small that shocks are not formed. The formulae for the amplitudes and phases of the various harmonics take a particularly simple form when the initial wave-form is sinusoidal and the non-linearity of the dielectric is not too great.The results are compared with those obtained by the usual methods of calculation which assume that only harmonics of very low order are generated. The discrepancy in the amplitudes of these low order harmonics, calculated by the two methods is, for most practical purposes, insignificant.

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Résumé Nous discutons la propagation d'une onde électromagnétique plane dans un milieu diélectrique, non-linéaire, non-dissipatif et isotrope. Nous donnons une méthode pour le calcul du changement des amplitudes et des phases des harmoniques d'ordres variés. Les calculs sont valides sous la condition que la distance parcourue par l'onde n'est pas assez grande pour le développement d'un choc. Nous faisons la comparaison entre nos résultats et ceux qui sont obtenus par les méthodes usuelles dans lesquelles on fait l'hypothèse que seulement les harmoniques de petits ordres sont produites. Les différences entre les amplitudes des harmoniques de petits ordres, calculées par les deux méthodes, ne sont pas importantes du point de vue pratique. D'autre part, notre méthode est valable pour le calcul des amplitudes et des phases des harmoniques de tous les ordres pour une onde d'une forme quelconque.