Effectiveness of Pricing Strategies on French Fries and Fruit Purchases among University Students: Results from an On-Campus Restaurant Experiment

ObjectivesThis study examined the effect of a 10 and 20% meal price increase when choosing French fries and a 10 and 20% meal price reduction when choosing fruit for dessert on university students’ purchasing behaviour in an on-campus restaurant. The moderating effect of gender was also investigated. Secondly, this study aimed at gaining further insight into reasons why these price manipulations did or did not change students’ purchasing behaviour.SignificancePricing may be a promising strategy to improve university students’ eating behaviour. The likelihood of intervention success may increase when combining pricing strategies with offering healthy, tasty and meal matching starchy alternatives to French fries and offering a variety of fresh and appealing fruits.     

The ROSA26-iPSC Mouse: A Conditional,Inducible, and Exchangeable Resource for Studying Cellular (De)Differentiation

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Highlights? Conditional and inducible reprogrammable mouse model presented ? Allows removal of the Yamanaka factors after reprogramming ? Fully and partially reprogrammed endothelial cells generated ? Lineage-directed differentiation of iPSCs toward beating cardiomyocytes     

Pharmacological Characterization of an Antisense Knockdown Zebrafish Model of Dravet Syndrome: Inhibition of Epileptic Seizures by the Serotonin Agonist Fenfluramine

Dravet syndrome (DS) is one of the most pharmacoresistant and devastating forms of childhood epilepsy syndromes. Distinct de novo mutations in the SCN1A gene are responsible for over 80% of DS cases. While DS is largely resistant to treatment with existing anti-epileptic drugs, promising results have been obtained in clinical trials with human patients treated with the serotonin agonist fenfluramine as an add-on therapeutic. We developed a zebrafish model of DS using morpholino antisense oligomers (MOs) targeting scn1Lab, the zebrafish ortholog of SCN1A. Zebrafish larvae with an antisense knockdown of scn1Lab (scn1Lab morphants) were characterized by automated behavioral tracking and high-resolution video imaging, in addition to measuring brain activity through local field potential recordings. Our findings reveal that scn1Lab morphants display hyperactivity, convulsive seizure-like behavior, loss of posture, repetitive jerking and a myoclonic seizure-like pattern. The occurrence of spontaneous seizures was confirmed by local field potential recordings of the forebrain, measuring epileptiform discharges. Furthermore, we show that these larvae are remarkably sensitive to hyperthermia, similar to what has been described for mouse models of DS, as well as for human DS patients. Pharmacological evaluation revealed that sodium valproate and fenfluramine significantly reduce epileptiform discharges in scn1Lab morphants. Our findings for this zebrafish model of DS are in accordance with clinical data for human DS patients. To our knowledge, this is the first study demonstrating effective seizure inhibition of fenfluramine in an animal model of Dravet syndrome. Moreover, these results provide a basis for identifying novel analogs with improved activity and significantly milder or no side effects.     

Interplay between metal binding and cis/trans isomerization in legume lectins: structural and thermodynamic study of P. angolensis lectin

The interplay between metal binding, carbohydrate binding activity, stability and structure of the lectin from Pterocarpus angolensis was investigated. Removal of the metals leads to a more flexible form of the protein with significantly less conformational stability. Crystal structures of this metal-free form show significant structural rearrangements, although some structural features that allow the binding of sugars are retained. We propose that substitution of an asparagine residue at the start of the C-terminal beta-strand of the legume lectin monomer hinders the trans-isomerization of the cis-peptide bond upon demetallization and constitutes an intramolecular switch governing the isomer state of the non-proline bond and ultimately the lectin phenotype.     

Impact of variance components on reliability of absolute quantification using digital PCR

Background

Digital polymerase chain reaction (dPCR) is an increasingly popular technology for detecting and quantifying target nucleic acids. Its advertised strength is high precision absolute quantification without needing reference curves. The standard data analytic approach follows a seemingly straightforward theoretical framework but ignores sources of variation in the data generating process. These stem from both technical and biological factors, where we distinguish features that are 1) hard-wired in the equipment, 2) user-dependent and 3) provided by manufacturers but may be adapted by the user. The impact of the corresponding variance components on the accuracy and precision of target concentration estimators presented in the literature is studied through simulation.

Results

We reveal how system-specific technical factors influence accuracy as well as precision of concentration estimates. We find that a well-chosen sample dilution level and modifiable settings such as the fluorescence cut-off for target copy detection have a substantial impact on reliability and can be adapted to the sample analysed in ways that matter. User-dependent technical variation, including pipette inaccuracy and specific sources of sample heterogeneity, leads to a steep increase in uncertainty of estimated concentrations. Users can discover this through replicate experiments and derived variance estimation. Finally, the detection performance can be improved by optimizing the fluorescence intensity cut point as suboptimal thresholds reduce the accuracy of concentration estimates considerably.

Conclusions

Like any other technology, dPCR is subject to variation induced by natural perturbations, systematic settings as well as user-dependent protocols. Corresponding uncertainty may be controlled with an adapted experimental design. Our findings point to modifiable key sources of uncertainty that form an important starting point for the development of guidelines on dPCR design and data analysis with correct precision bounds. Besides clever choices of sample dilution levels, experiment-specific tuning of machine settings can greatly improve results. Well-chosen data-driven fluorescence intensity thresholds in particular result in major improvements in target presence detection. We call on manufacturers to provide sufficiently detailed output data that allows users to maximize the potential of the method in their setting and obtain high precision and accuracy for their experiments.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2105-15-283) contains supplementary material, which is available to authorized users.     

Ordering of neuronal apoptosis signaling: a superoxide burst precedes mitochondrial cytochrome <Emphasis Type="Italic">c</Emphasis> release in a growth factor deprivation model

Axonal injury to retinal ganglion cells, a defined central neuron, induces a burst of intracellular superoxide anion that precedes externalization of membrane phosphatidylserine and subsequent apoptotic cell death. Dismutation of superoxide prevents the signal and delays loss of these cells, consistent with superoxide being necessary for transduction of the axotomy signal. However, phosphatidylserine externalization is a relatively late step in apoptosis, and it is possible that the superoxide burst is not an early axotomy signal but rather a result of cytochrome c release from the mitochondrial inner membrane with consequent accumulation of reduced intermediates. Other possibilities are that both superoxide generation and cytochrome c release are induced in parallel by axotomy, or that cytochrome c release potentiates the effect of the superoxide burst. To distinguish these various possibilities, serum-deprived neuronal retinal cells were assayed in vitro for superoxide elevation and release of cytochrome c from mitochondria, and the distribution of these two markers across a large number of cells used to model the temporal ordering of events. Based on this model of factor-dependent cell death, superoxide precedes, and possibly potentiates, cytochrome c release, and thus the former is likely an early signal for certain types of neuronal apoptosis in the central nervous system.     

Induction of Neuronal Morphology in the 661W Cone Photoreceptor Cell Line with Staurosporine

Purpose

RGC-5 cells undergo differentiation into a neuronal phenotype with low concentrations of staurosporine. Although the RGC-5 cell line was initially thought to be of retinal ganglion cell origin, recent evidence suggests that the RGC-5 line could have been the result of contamination with 661W mouse cone photoreceptor cells. This raised the possibility that a cone photoreceptor cell line could be multipotent and could be differentiated to a neuronal phenotype.

Methods

661W and RGC-5 cells, non-neuronal retinal astrocytes, retinal endothelial cells, retinal pericytes, M21 melanoma cells, K562 chronic myelogenous leukemia cells, and Daudi Burkitt lymphoma cells, were differentiated with staurosporine. The resulting morphology was quantitated using NeuronJ with respect to neurite counts and topology.

Results

Treatment with staurosporine induced similar-appearing morphological differentiation in both 661W and RGC-5 cells. The following measures were not significantly different between 661W and RGC-5 cells: number of neurites per cell, total neurite field length, number of neurite branch points, and cell viability. Neuronal-like differentiation was not observed in the other cell lines tested.

Conclusions

661W and RGC-5 cells have virtually identical and distinctive morphology when differentiated with low concentrations of staurosporine. This result demonstrates that a retinal neuronal precursor cell with cone photoreceptor lineage can be differentiated to express a neuronal morphology.     

Productivity of a Polish child’s inflectional noun morphology: a naturalistic study

In the current paper, we examine the degree to which a 2-year-old Polishspeaking child exhibits productivity in her use of noun morphology. Using densely collected naturalistic data (five recording sessions per week) we assess the range of noun inflections she produces, the degree of productivity in her use of individual nouns, and the contextual productivity in her use of individual inflections. We adopt careful controls to allow comparison between the child’s noun use and that of her caregiver. Our data show that although the child uses the same range of noun inflections as her mother, she shows a much more limited productivity in her use of both individual nouns and individual inflections with respect to their contexts of use. We discuss the results in the light of two different theoretical approaches to inflectional morphology: the usage-based, schema approach and the rule-based approach.