Surface Reconstruction of the Surgical Field From Stereoscopic Microscope Views in Neurosurgery

Introduction In neurosurgery, guidance systems, which correlate patient imaging data to the surgical field using tracked probes or surgical microscopes, have become standard equipment. The most advanced systems dispose of an additional head-up display showing relevant information on a two-dimensional graphical overlay directly within one of the oculars of the microscope. Our experience has shown that to take full advantage of augmented reality, more complex colour and stereoscopic displays are needed for a better understanding and interpretation of the overlaid information [1]. Therefore, this basic overlay will be replaced in future by more sophisticated three-dimensional displays being able to render stereoscopic views of a virtual scene. Today's augmented reality, where the real scene's information is enhanced with additional information, might be backed by augmented virtuality [2,3]. Augmented virtuality fuses multimodal scene information acquired during planning with real-time i

Ran GTPase Cycle and Importins α and β Are Essential for Spindle Formation and Nuclear Envelope Assembly in Living Caenorhabditis elegans Embryos

The small GTPase Ran has been found to play pivotal roles in several aspects of cell function. We have investigated the role of the Ran GTPase cycle in spindle formation and nuclear envelope assembly in dividing Caenorhabditis elegans embryos in real time. We found that Ran and its cofactors RanBP2, RanGAP, and RCC1 are all essential for reformation of the nuclear envelope after cell division. Reducing the expression of any of these components of the Ran GTPase cycle by RNAi leads to strong extranuclear clustering of integral nuclear envelope proteins and nucleoporins. Ran, RanBP2, and RanGAP are also required for building a mitotic spindle, whereas astral microtubules are normal in the absence of these proteins. RCC1(RNAi) embryos have similar abnormalities in the initial phase of spindle formation but eventually recover to form a bipolar spindle. Irregular chromatin structures and chromatin bridges due to spindle failure were frequently observed in embryos where the Ran cycle was perturbed. In addition, connection between the centrosomes and the male pronucleus, and thus centrosome positioning, depends upon the Ran cycle components. Finally, we have demonstrated that both IMA-2 and IMB-1, the homologues of vertebrate importin α and β, are essential for both spindle assembly and nuclear formation in early embryos