Towards a Robuster Interpretive Parsing

The input data to grammar learning algorithms often consist of overt forms that do not contain full structural descriptions. This lack of information may contribute to the failure of learning. Past work on Optimality Theory introduced Robust Interpretive Parsing (RIP) as a partial solution to this problem. We generalize RIP and suggest replacing the winner candidate with a weighted mean violation of the potential winner candidates. A Boltzmann distribution is introduced on the winner set, and the distribution’s parameter $T$ is gradually decreased. Finally, we show that GRIP, the Generalized Robust Interpretive Parsing Algorithm significantly improves the learning success rate in a model with standard constraints for metrical stress assignment

An intracellular traffic jam: Fc receptor-mediated transport of immunoglobulin G

Recent advances in imaging techniques along with more powerful in vitro and in vivo models of receptor-mediated ligand transport are facilitating advances in our understanding of how cells efficiently direct receptors and their cargo to target destinations within the cytoplasm and at the plasma membrane. Specifically, light and 3D electron microscopy studies examining the trafficking behavior of the neonatal Fc receptor (FcRn), a transport receptor for immunoglobulin G (IgG), have given us new insights into the dynamic interplay between the structural components of the cytosolic trafficking machinery, its protein regulators, and the receptors it directs to various locations within the cell. These studies build upon previous biochemical characterizations of FcRn transport and are allowing us to begin formulation of a more complete model for the intracellular trafficking of receptor–ligand complexes

Comparison of FcRn- and pIgR-Mediated Transport in MDCK Cells by Fluorescence Confocal Microscopy

Protein delivery across polarized epithelia is controlled by receptor-mediated transcytosis. Many studies have examined basolateral-to-apical trafficking of polymeric IgA (pIgA) by the polymeric immunoglobulin receptor (pIgR). Less is known about apical-to-basolateral transcytosis, the direction the neonatal Fc receptor (FcRn) transports maternal IgGs across intestinal epithelia. To compare apical-to-basolateral and basolateral-to-apical transcytosis, we co-expressed FcRn and pIgR in Madin-Darby canine kidney (MDCK) cells and used pulse-chase experiments with confocal microscopy to examine transport of apically applied IgG Fcγ and basolaterally applied pIgA. Fcγ and pIgA trafficking routes were initially separate but intermixed at later chase times. Fcγ was first localized near the apical surface, but became more equally distributed across the cell, consistent with concomitant transcytosis and recycling. By contrast, pIgA transport was strongly unidirectional: pIgA shifted from near the basolateral surface to an apical location with increasing time. Some Fcγ and pIgA fluorescence colocalized in early (EEA1-positive), recycling (Rab11a-positive), and transferrin (Tf)-positive common/basolateral recycling endosomes. Fcγ became more enriched in Tf-positive endosomes with time, whereas pIgA was sorted from these compartments. Live-cell imaging revealed that vesicles containing Fcγ or pIgA shared similar mobility characteristics and were equivalently affected by depolymerizing microtubules, indicating that both trafficking routes depended to roughly the same extent on intact microtubules

Intracellular neutralization of viral infection in polarized epithelial cells by neonatal Fc receptor (FcRn)-mediated IgG transport

IgG was traditionally thought to neutralize virions by blocking their attachment to or penetration into mucosal epithelial cells, a common site of exposure to viruses. However, we describe an intracellular neutralizing action for an influenza hemagglutinin-specific monoclonal antibody, Y8-10C2 (Y8), which has neutralizing activity only at an acidic pH. When Y8 was applied to the basolateral surface of Madin–Darby canine kidney cells expressing the rat neonatal Fc receptor for IgG (FcRn), it significantly reduced viral replication following apical exposure of the cell monolayer to influenza virus. Virus neutralization by Y8 mAb was dependent on FcRn expression and its transport of IgG. As both FcRn and Y8 mAb bind their partners only at acidic pH, the Y8 mAb is proposed to carry out its antiviral activity intracellularly. Furthermore, the virus, Y8 mAb, and FcRn colocalized within endosomes, possibly inhibiting the fusion of viral envelopes with endosomal membranes during primary uncoating, and preventing the accumulation of the neutralized viral nucleoprotein antigen in the nucleus. Prophylactic administration of Y8 mAb before viral challenge in WT mice, but not FcRn-KO mice, conferred protection from lethality, prevented weight loss, resulted in a significant reduction in pulmonary virus titers, and largely reduced virus-induced lung pathology. Thus, this study reveals an intracellular mechanism for viral neutralization in polarized epithelial cells that is dependent on FcRn-mediated transport of neutralizing IgG

The Chicken Yolk Sac IgY Receptor, a Mammalian Mannose Receptor Family Member, Transcytoses IgY across Polarized Epithelial Cells

In mammals the transfer of passive immunity from mother to young is mediated by the MHC-related receptor FcRn, which transports maternal IgG across epithelial cell barriers. In birds, maternal IgY in egg yolk is transferred across the yolk sac to passively immunize chicks during gestation and early independent life. The chicken yolk sac IgY receptor (FcRY) is the ortholog of the mammalian phospholipase A2 receptor, a mannose receptor family member, rather than an FcRn or MHC homolog. FcRn and FcRY both exhibit ligand binding at the acidic pH of endosomes and ligand release at the slightly basic pH of blood. Here we show that FcRY expressed in polarized mammalian epithelial cells functioned in endocytosis, bidirectional transcytosis, and recycling of chicken FcY/IgY. Confocal immunofluorescence studies demonstrated that IgY binding and endocytosis occurred at acidic but not basic pH, mimicking pH-dependent uptake of IgG by FcRn. Colocalization studies showed FcRY-mediated internalization via clathrin-coated pits and transport involving early and recycling endosomes. Disruption of microtubules partially inhibited apical-to-basolateral and basolateral-to-apical transcytosis, but not recycling, suggesting the use of different trafficking machinery. Our results represent the first cell biological evidence of functional equivalence between FcRY and FcRn and provide an intriguing example of how evolution can give rise to systems in which similar biological requirements in different species are satisfied utilizing distinct protein folds

Synchronous Firing Variable Binding is a Tensor Product Representation with Temporal Role Vectors

Synchronous firing of neural units has recently been proposed as a new way of solving the variable binding problem in connectionist networks. Firing synchrony appears to be unrelated to earlier methods of variable binding, nearly all of which can be analyzed as species of tensor product representations, where vectors representing variables and values are bound together with the outer product. In this paper, we argue that, despite appearances, firing synchrony is also a case of tensor product representation. This analysis exposes two logically independent components of the synchronous firing idea. The most obvious is the idea of using time as a resource: spatio-temporal patterns of activation are used. This, we argue, is a purely implementational issue which does not bear on the complexity issues of variable binding. In contrast, the second idea does bear on genuinely representational issues, and is the source of most of the formal properties claimed for the synchrony scheme. Rather than explicitly binding a semantic role like giver to a semantic filler like John, these two are implicitly bound—by explicitly binding each to a common formal role, via the tensor product. The analysis situates synchronous firing in a typology of alternative variable binding schemes

A freeze substitution fixation-based gold enlarging technique for EM studies of endocytosed nanogold-labeled molecules

We have developed methods to locate individual ligands that can be used for electron microscopy studies of dynamic events during endocytosis and subsequent intracellular trafficking. The methods are based on enlargement of 1.4 nm Nanogold attached to an endocytosed ligand. Nanogold, a small label that does not induce misdirection of ligand–receptor complexes, is ideal for labeling ligands endocytosed by live cells, but is too small to be routinely located in cells by electron microscopy. Traditional pre-embedding enhancement protocols to enlarge Nanogold are not compatible with high pressure freezing/freeze substitution fixation (HPF/FSF), the most accurate method to preserve ultrastructure and dynamic events during trafficking. We have developed an improved enhancement procedure for chemically fixed samples that reduced auto-nucleation, and a new pre-embedding gold enlarging technique for HPF/FSF samples that preserved contrast and ultrastructure and can be used for high-resolution tomography. We evaluated our methods using labeled Fc as a ligand for the neonatal Fc receptor. Attachment of Nanogold to Fc did not interfere with receptor binding or uptake, and gold-labeled Fc could be specifically enlarged to allow identification in 2D projections and in tomograms. These methods should be broadly applicable to many endocytosis and transcytosis studies

Dutch and German 3-year-olds’ representations of voicing alternations

The voicing contrast is neutralised syllable and word finally in Dutch and German, leading to alternations within the morphological paradigm (e.g. Dutch ‘bed(s)’, be[t] be[d]en, German ‘dog(s)’, Hun[t]-Hun[d]e). Despite structural similarity, language-specific morphological, phonological and lexical properties impact on the distribution of this alternation in the two languages. Previous acquisition research has focused on one language only, predominantly focusing on children’s production accuracy, concluding that alternations are not acquired until late in the acquisition process in either language. This paper adapts a perceptual method to investigate how voicing alternations are represented in the mental lexicon of Dutch and German 3-year-olds. Sensitivity to mispronunciations of voicing word-medially in plural forms was measured using a visual fixation procedure. Dutch children exhibited evidence of overgeneralising the voicing alternation, whereas German children consistently preferred the correct pronunciation to mispronunciations. Results indicate that the acquisition of voicing alternations is influenced by language-specific factors beyond the alternation itself

Pion and proton showers in the CALICE scintillator-steel analogue hadron calorimeter

Showers produced by positive hadrons in the highly granular CALICE scintillator-steel analogue hadron calorimeter were studied. The experimental data were collected at CERN and FNAL for single particles with initial momenta from 10 to 80 GeV/c. The calorimeter response and resolution and spatial characteristics of shower development for proton- and pion-induced showers for test beam data and simulations using Geant4 version 9.6 are compared.Comment: 26 pages, 16 figures, JINST style, changes in the author list, typos corrected, new section added, figures regrouped. Accepted for publication in JINS

How changes in reimbursement practices influence the financial sustainability of medicine policy: Lessons learned from Slovakia

Objectives: The aim of this study was to review the impact of new reimbursement requirements for medicines in the Slovak Republic based on legislation that came into force in January 2018. Methods: The new legislation was reviewed. The reimbursement dossiers for medicines and health technology assessments and appraisals, justifications for reimbursement decisions, final reimbursement decisions, and all aspects of the appeal mechanisms have been transparently published on the website of the Slovak Ministry of Health and were used for this analysis. Results: Based on the new legislation, there was no need to submit information about relative effectiveness and cost-effectiveness of medicines with less than 1:50,000 eligible patients prior to reimbursement decisions, and the cost-effectiveness threshold has been increased for all other medicines. The estimated impact of the 2-year budget for the 59 medicines submitted for reimbursement without relative effectiveness and cost-effectiveness analysis was €181,273,698, based on the published submission dossiers. The estimated impact of the 2-year budget for the 45 medicines with evidence of relative effectiveness and cost-effectiveness was €178,566,634. In contrast to the easier market access criteria for new original medicines, the new legislation enforces stricter price erosion criteria for generic and biosimilar medicines. Consequently, the number of generic and biosimilar entries was reduced from 242 in 2017 to 224 in 2018. Conclusions: Although some of the new reimbursement applications were not approved by the Ministry of Health, many new medicines were added to the Slovak pharmaceutical reimbursement list based on "balanced assessment" requirements; hence, the system became financially unsustainable. It was necessary to change the legislation from January 2019.</p