Search results for " entry"
showing 10 items of 131 documents
Excessive vs. insufficient entry in spatial models: When product design and market size matter
2020
Abstract Under spatial product differentiation and product design, we identify conditions for either excessive or insufficient firm entry. We extend previous settings, based on the Salop circular model, to analyze the combined role of positive demand elasticity and endogenous targeted product design. First, we show that, given the number of firms, the equilibrium level of targeted design is either excessive or insufficient, depending on demand elasticity. Second, with free entry, we show that the degree of targeted product design increases with the relative market size and decreases with demand elasticity. Based on these effects, the interplay between demand elasticity and market size yield…
The Sphingosine Kinase-1 Activator, K6PC-5, Attenuates the Ebola Virus Infection and the Virus Induced Cell Death
2020
Ebola virus (EBOV) is responsible for outbreaks with case-fatality rates of up to 90% and for an epidemic in West Africa with more than ten thousand deaths. EBOV glycoprotein (EBOV-GP) is the only viral surface protein and is responsible for viral entry into cells. It has been suggested to play a role in the cytopathic effects induced by the virus. Here we uncover a critical role for sphingolipids in inhibiting viral entry and virus-mediated cytotoxicity. Sphingosine kinase 1 (SphK1) catalyzes the phosphorylation of sphingosine to sphingosine-1-phosphate (S1P). The administration of the SphK1 activator, K6PC-5, or S1P, or the overexpression of SphK1 consistently exhibited striking inhibito…
Calpain 1 and 2 Are Required for RNA Replication of Echovirus 1▿
2007
ABSTRACT Calpains are calcium-dependent cysteine proteases that degrade cytoskeletal and cytoplasmic proteins. We have studied the role of calpains in the life cycle of human echovirus 1 (EV1). The calpain inhibitors, including calpeptin, calpain inhibitor 1, and calpain inhibitor 2 as well as calpain 1 and calpain 2 short interfering RNAs, completely blocked EV1 infection in the host cells. The effect of the inhibitors was not specific for EV1, because they also inhibited infection by other picornaviruses, namely, human parechovirus 1 and coxsackievirus B3. The importance of the calpains in EV1 infection also was supported by the fact that EV1 increased calpain activity 3 h postinfection. …
Cell Susceptibility to Baculovirus Transduction and Echovirus Infection Is Modified by Protein Kinase C Phosphorylation and Vimentin Organization
2013
ABSTRACT Some cell types are more susceptible to viral gene transfer or virus infection than others, irrespective of the number of viral receptors or virus binding efficacy on their surfaces. In order to characterize the cell-line-specific features contributing to efficient virus entry, we studied two cell lines (Ea.hy926 and MG-63) that are nearly nonpermissive to insect-specific baculovirus (BV) and the human enterovirus echovirus 1 (EV1) and compared their characteristics with those of a highly permissive (HepG2) cell line. All the cell lines contained high levels of viral receptors on their surfaces, and virus binding was shown to be efficient. However, in nonpermissive cells, BV and it…
Proteomic composition of Nipah virus-like particles
2017
Abstract Virions are often described as virus-only entities with no cellular components with the exception of the lipids in their membranes. However, advances in proteomics are revealing substantial amounts of host proteins in the viral particles. In the case of Nipah virus (NiV), the viral components in the virion have been known for some time. Nonetheless, no information has been obtained regarding the cellular proteins in the viral particles. To address this question, we produced Virus-Like Particles (VLPs) for NiV by expressing the F, G and M proteins in human-derived cells. Next, the proteomic content in these VLPs was analyzed by LC-MS/MS. We identified 67 human proteins including sol…
Clathrin-independent entry of baculovirus triggers uptake of E. coli in non-phagocytic human cells
2008
The prototype baculovirus, Autographa californica multiple nucleopolyhedrovirus, an insect pathogen, holds great potential as a gene therapy vector. To develop transductional targeting and gene delivery by baculovirus, we focused on characterizing the nature and regulation of its uptake in human cancer cells. Baculovirus entered the cells along fluid-phase markers from the raft areas into smooth-surfaced vesicles devoid of clathrin. Notably, regulators associated with macropinocytosis, namely EIPA, Pak1, Rab34, and Rac1, had no significant effect on viral transduction, and the virus did not induce fluid-phase uptake. The internalization and nuclear uptake was, however, affected by mutants o…
Improving baculovirus transduction of mammalian cells by surface display of a RGD-motif
2006
An RGD-containing peptide, comprising 23 amino acids from the foot-and-mouth disease virus (FMDV) VP1 protein was engineered into the envelope of Autographa californica nuclear polyhedrosis virus surface (AcNPV) using two different display strategies. The RGD-motif is a well-described tripeptide, that by binding to cell surface integrins facilitates virus entry into cells. This epitope was displayed, either by directly modifying the native major envelope protein gp64 of AcNPV, or by incorporating a second, modified version of gp64 onto the virus surface. Transduction efficiencies of four mammalian cell lines were compared by detecting the expression of the reporter gene green fluorescent pr…
Marte Meo as a port of entry to parental sensitivity - a three–case study
2019
Abstract Background Early parent- child relations play an important role in children’s development. Therapeutic intervention towards infants and toddlers at high-risk intends to prevent mental health problems. In this work, the parent-child-dyad is crucial. The video interaction guidance method, Marte Meo, is one among different methods used in attachment-based treatment in an outpatient infant mental health clinic. Parental sensitivity towards infants and toddlers needs is considered significant in developing secure attachment. Secure attachment is further considered decisive for mental health and the extent to which children are at risk of developing mental health problems. Different trea…
The Sylos Postulate reconsidered
2016
This chapter makes a textual comparison between the 1957 2nd Italian edition and the 1962 1st American edition of Oligopoly and Technical Progress, showing that Sylos Labini added to the later edition some fresh sections concerning new firms’ entry and incumbents’ reaction which partially contradict Modigliani’s 1958 presentation of the Sylos Postulate. The theoretical differences between Sylos Labini and Modigliani with regard to the assumption of constant output are traced back to their different modelling strategies on how to tackle the issue of external firms’ conjectures in determining the long-run oligopoly equilibrium price.
Paolo Sylos Labini Vindicated
2017
In the first part of our chapter we critically discuss i) Modigliani’s 1958 interpretation of Sylos Labini’s Oligopolio e Progresso Tecnico (1957), ii) the following debate concerning the Sylos Postulate −the assumption according to which “potential entrants behave as though they expected existing firms to adopt the policy most unfavourable to them, namely, the policy of maintaining output while reducing the price (or accepting reductions) to the extent required to enforce such an output policy” − and iii) the incumbent’s choice of productive capacity to install as strategic entry deterrence. In the second part of the chapter we develop a model in which, as in Dixit (1980), there are three …