Display aids for remote control of untethered undersea vehicles

A predictor display superimposed on slow-scan video or sonar data is proposed as a method to allow better remote manual control of an untethered submersible. Simulation experiments show good control under circumstances which otherwise make control practically impossible

The facilitating effects of uncertainty in long-term manual control

A 40-minute tracking task with different disturbance inputs was used to look for the effects of reduced task demands on long term manual control. The expected facilitating effects of task difficulty are hard to find. The decrements in performance over the run are no greater for the easier tasks. The detrimental effects of lower demand appear to be increased relative variability in performance, and possibly reduced performance on transition to unexpected, more difficult tasks. An information measure, including the effects of 'self-induced' uncertainty is developed as a work-load measure. There is a positive correlation between this 'self-induced work-load' and performance decrement for the easiest task, just the opposite of what the facilitation hypothesis would predict

Human/computer control of undersea teleoperators

The potential of supervisory controlled teleoperators for accomplishment of manipulation and sensory tasks in deep ocean environments is discussed. Teleoperators and supervisory control are defined, the current problems of human divers are reviewed, and some assertions are made about why supervisory control has potential use to replace and extend human diver capabilities. The relative roles of man and computer and the variables involved in man-computer interaction are next discussed. Finally, a detailed description of a supervisory controlled teleoperator system, SUPERMAN, is presented

cGMP via PKG activates 26S proteasomes and enhances degradation of proteins, including ones that cause neurodegenerative diseases.

Because raising cAMP enhances 26S proteasome activity and the degradation of cell proteins, including the selective breakdown of misfolded proteins, we investigated whether agents that raise cGMP may also regulate protein degradation. Treating various cell lines with inhibitors of phosphodiesterase 5 or stimulators of soluble guanylyl cyclase rapidly enhanced multiple proteasome activities and cellular levels of ubiquitinated proteins by activating protein kinase G (PKG). PKG stimulated purified 26S proteasomes by phosphorylating a different 26S component than is modified by protein kinase A. In cells and cell extracts, raising cGMP also enhanced within minutes ubiquitin conjugation to cell proteins. Raising cGMP, like raising cAMP, stimulated the degradation of short-lived cell proteins, but unlike cAMP, also markedly increased proteasomal degradation of long-lived proteins (the bulk of cell proteins) without affecting lysosomal proteolysis. We also tested if raising cGMP, like cAMP, can promote the degradation of mutant proteins that cause neurodegenerative diseases. Treating zebrafish models of tauopathies or Huntington's disease with a PDE5 inhibitor reduced the levels of the mutant huntingtin and tau proteins, cell death, and the resulting morphological abnormalities. Thus, PKG rapidly activates cytosolic proteasomes, protein ubiquitination, and overall protein degradation, and agents that raise cGMP may help combat the progression of neurodegenerative diseases

Discovery of 1,3-Diaminobenzenes as Selective Inhibitors of Platelet Activation at the PAR1 Receptor

A high-throughput screen of the NIH-MLSMR compound collection, along with a series of secondary assays to identify potential targets of hit compounds, previously identified a 1,3-diaminobenzene scaffold that targets protease-activated receptor 1 (PAR1). We now report additional structure–activity relationship (SAR) studies that delineate the requirements for activity at PAR1 and identify plasma-stable analogues with nanomolar inhibition of PAR1-mediated platelet activation. Compound 4 was declared as a probe (ML161) with the NIH Molecular Libraries Program. This compound inhibited platelet aggregation induced by a PAR1 peptide agonist or by thrombin but not by several other platelet agonists. Initial studies suggest that ML161 is an allosteric inhibitor of PAR1. These findings may be important for the discovery of antithrombotics with an improved safety profile

Adaptive Gesture Recognition with Variation Estimation for Interactive Systems

This paper presents a gesture recognition/adaptation system for Human Computer Interaction applications that goes beyond activity classification and that, complementary to gesture labeling, characterizes the movement execution. We describe a template-based recognition method that simultaneously aligns the input gesture to the templates using a Sequential Montecarlo inference technique. Contrary to standard template- based methods based on dynamic programming, such as Dynamic Time Warping, the algorithm has an adaptation process that tracks gesture variation in real-time. The method continuously updates, during execution of the gesture, the estimated parameters and recognition results which offers key advantages for continuous human-machine interaction. The technique is evaluated in several different ways: recognition and early recognition are evaluated on a 2D onscreen pen gestures; adaptation is assessed on synthetic data; and both early recognition and adaptation is evaluation in a user study involving 3D free space gestures. The method is not only robust to noise and successfully adapts to parameter variation but also performs recognition as well or better than non-adapting offline template-based methods

Mobilization of HIV Spread by Diaphanous 2 Dependent Filopodia in Infected Dendritic Cells

Paramount to the success of persistent viral infection is the ability of viruses to navigate hostile environments en route to future targets. In response to such obstacles, many viruses have developed the ability of establishing actin rich-membrane bridges to aid in future infections. Herein through dynamic imaging of HIV infected dendritic cells, we have observed how viral high-jacking of the actin/membrane network facilitates one of the most efficient forms of HIV spread. Within infected DC, viral egress is coupled to viral filopodia formation, with more than 90% of filopodia bearing immature HIV on their tips at extensions of 10 to 20 µm. Live imaging showed HIV filopodia routinely pivoting at their base, and projecting HIV virions at µm.sec−1 along repetitive arc trajectories. HIV filopodial dynamics lead to up to 800 DC to CD4 T cell contacts per hour, with selection of T cells culminating in multiple filopodia tethering and converging to envelope the CD4 T-cell membrane with budding HIV particles. Long viral filopodial formation was dependent on the formin diaphanous 2 (Diaph2), and not a dominant Arp2/3 filopodial pathway often associated with pathogenic actin polymerization. Manipulation of HIV Nef reduced HIV transfer 25-fold by reducing viral filopodia frequency, supporting the potency of DC HIV transfer was dependent on viral filopodia abundance. Thus our observations show HIV corrupts DC to CD4 T cell interactions by physically embedding at the leading edge contacts of long DC filopodial networks

The p12 Domain Is Unstructured in a Murine Leukemia Virus p12-CAN Gag Construct

The Gag polyproteins of gammaretroviruses contain a conserved p12 domain between MA and CA that plays critical roles in virus assembly, reverse transcription and nuclear integration. Here we show using nuclear magnetic resonance, that p12 is unstructured in a Moloney murine leukemia virus (MMLV) Gag fragment that includes the N-terminal domain of CA (p12-CAN). Furthermore, no long range interactions were observed between the domains, as has been previously predicted. Flexibility appears to be a common feature of Gag “late” domains required for virus release during budding. Residues near the N-terminus of CAN that form a β-hairpin in the mature CA protein are unfolded in p12-CAN, consistent with proposals that hairpin formation helps trigger capsid assembly

Cryo Electron Tomography of Native HIV-1 Budding Sites

The structure of immature and mature HIV-1 particles has been analyzed in detail by cryo electron microscopy, while no such studies have been reported for cellular HIV-1 budding sites. Here, we established a system for studying HIV-1 virus-like particle assembly and release by cryo electron tomography of intact human cells. The lattice of the structural Gag protein in budding sites was indistinguishable from that of the released immature virion, suggesting that its organization is determined at the assembly site without major subsequent rearrangements. Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells. It displays the same hexagonal symmetry and spacing in the MA-CA layer as the immature lattice, but lacks density corresponding to NC-RNA-p6. Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation. We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles

Functional Interchangeability of Late Domains, Late Domain Cofactors and Ubiquitin in Viral Budding

The membrane scission event that separates nascent enveloped virions from host cell membranes often requires the ESCRT pathway, which can be engaged through the action of peptide motifs, termed late (L-) domains, in viral proteins. Viral PTAP and YPDL-like L-domains bind directly to the ESCRT-I and ALIX components of the ESCRT pathway, while PPxY motifs bind Nedd4-like, HECT-domain containing, ubiquitin ligases (e.g. WWP1). It has been unclear precisely how ubiquitin ligase recruitment ultimately leads to particle release. Here, using a lysine-free viral Gag protein derived from the prototypic foamy virus (PFV), where attachment of ubiquitin to Gag can be controlled, we show that several different HECT domains can replace the WWP1 HECT domain in chimeric ubiquitin ligases and drive budding. Moreover, artificial recruitment of isolated HECT domains to Gag is sufficient to stimulate budding. Conversely, the HECT domain becomes dispensable if the other domains of WWP1 are directly fused to an ESCRT-1 protein. In each case where budding is driven by a HECT domain, its catalytic activity is essential, but Gag ubiquitination is dispensable, suggesting that ubiquitin ligation to trans-acting proteins drives budding. Paradoxically, however, we also demonstrate that direct fusion of a ubiquitin moiety to the C-terminus of PFV Gag can also promote budding, suggesting that ubiquitination of Gag can substitute for ubiquitination of trans-acting proteins. Depletion of Tsg101 and ALIX inhibits budding that is dependent on ubiquitin that is fused to Gag, or ligated to trans-acting proteins through the action of a PPxY motif. These studies underscore the flexibility in the ways that the ESCRT pathway can be engaged, and suggest a model in which the identity of the protein to which ubiquitin is attached is not critical for subsequent recruitment of ubiquitin-binding components of the ESCRT pathway and viral budding to proceed