Variation in access to sugar-sweetened beverages in vending machines across rural, town and urban high schools.

OBJECTIVES: The 2010 Dietary Guidelines for Americans include reducing consumption of sugar-sweetened beverages. Among the many possible routes of access for youth, school vending machines provide ready availability of sugar-sweetened beverages. The purpose of this study was to determine variation in high school student access to sugar-sweetened beverages through vending machines by geographic location - urban, town or rural - and to offer an approach for analysing school vending machine content. STUDY DESIGN: Cross-sectional observational study. METHODS: Between October 2007 and May 2008, trained coders recorded beverage vending machine content and machine-front advertising in 113 machines across 26 schools in New Hampshire and Vermont, USA. RESULTS: Compared with town schools, urban schools were significantly less likely to offer sugar-sweetened beverages (P = 0.002). Rural schools also offered more sugar-sweetened beverages than urban schools, but this difference was not significant. Advertisements for sugar-sweetened beverages were highly prevalent in town schools. CONCLUSIONS: High school students have ready access to sugar-sweetened beverages through their school vending machines. Town schools offer the highest risk of exposure; school vending machines located in towns offer up to twice as much access to sugar-sweetened beverages in both content and advertising compared with urban locations. Variation by geographic region suggests that healthier environments are possible and some schools can lead as inspirational role models.

Avian adeno-associated virus-based expression of Newcastle disease virus hemagglutinin-neuraminidase protein for poultry vaccination.

The avian adeno-associated virus (AAAV) is a replication-defective nonpathogenic virus member of the family Parvoviridae that has been proved to be useful as a viral vector for gene delivery. The use of AAAV for transgenic expression of Newcastle disease virus (NDV) hemagglutinin-neuraminidase (HN) protein and its ability to induce immunity in chickens were assessed. Proposed advantages of this system include no interference with maternal antibodies, diminished immune response against the vector, and the ability to accommodate large fragments of genetic information. In this work the generation of recombinant AAAV virions expressing the HN protein (rAAAV-HN) was demonstrated by electron microscopy, immunocytochemistry, and western blot analysis. Serological evidence of HN protein expression after in ovo or intramuscular inoculation of the recombinant virus in specific-pathogen-free chickens was obtained. Serum from rAAAV-HN-vaccinated birds showed a systemic immune response evidenced by NDV-specific enzyme-linked immunosorbent assay and hemagglutination inhibition testing. Positive virus neutralization in embryonated chicken eggs and indirect immunofluorescence detection of NDV infected cells by serum from rAAAV-HN vaccinated birds is also reported. A vaccine-challenge experiment in commercial broiler chickens using a Venezuelan virulent viscerotropic strain of NDV was performed. All unvaccinated controls died within 5 days postchallenge. Protection up to 80% was observed in birds vaccinated in ovo and revaccinated at 7 days of age with the rAAAV-HN. The results demonstrate the feasibility of developing and using an AAAV-based gene delivery system for poultry vaccination.

Protection against infectious bursal disease virulent challenge conferred by a recombinant avian adeno-associated virus vaccine.

The development and use of recombinant vaccine vectors for the expression of poultry pathogens proteins is an active research field. The adeno-associated virus (AAV) is a replication-defective virus member of the family Parvoviridae that has been successfully used for gene delivery in humans and other species. In this experiment, an avian adeno-associated virus (AAAV) expressing the infectious bursal disease virus (IBDV) VP2 protein (rAAAV-VP2) was evaluated for protection against IBDV-virulent challenge. Specific pathogen free (SPF) birds were inoculated with rAAAV-VP2 or with a commercial intermediate IBDV vaccine and then challenged with the Edgar strain. IBDV-specific antibody levels were observed in all vaccinated groups; titers were higher for the commercial vaccine group. The live, commercial vaccine induced adequate protection against morbidity and mortality; nevertheless, initial lymphoid depletion and follicular atrophy related to active viral replication was observed as early as day 14 and persisted up to day 28, when birds were challenged. No bursal tissue damage due to rAAAV-VP2 vaccination was observed. Eight-out-of-ten rAAAV-VP2-vaccinated birds survived the challenge and showed no clinical signs. The bursa:body weight ratio and bursa lesion scores in the rAAAV-VP2 group indicated protection against challenge. Therefore, transgenic expression of the VP2 protein after rAAAV-VP2 vaccination induced protective immunity against IBDV challenge in 80% of the birds, without compromising the bursa of Fabricius. The use of rAAAV virions for gene delivery represents a novel approach to poultry vaccination.

Infectious bursal disease subunit vaccination.

Infectious bursal disease virus (IBDV) is the causative agent of infectious bursal disease, a nosologic entity with global economic importance in poultry. The viral protein 2 (VP2) is recognized as the virus' major antigenic protein. The goal of this study was to generate yeast (Pichia pastoris)-based protein expression from the VP2 gene of the Edgar strain of IBDV and from the hypervariable region of the VP2 gene (hvVP2) to test the protection afforded against virulent IBDV challenge when inoculated in chickens. The genetic material used for protein expression was obtained from paraffin-embedded tissue. Specific-pathogen-free chickens were vaccinated with the expressed products and challenged with the homologous strain (Edgar). After challenge, no morbidity or mortality was observed in the birds vaccinated with the whole VP2, compared with 30% morbidity and mortality in the hvVP2-vaccinated birds and with 90% morbidity and 60% mortality in the unvaccinated, challenged controls. Immunohistochemistry detection of the challenge virus and some extent of bursal damage were observed in all challenged birds, indicating active replication of the challenge virus despite vaccination. As determined by bursal index values, the protection against postchallenge bursal atrophy was significantly higher (P < 0.05) in the VP2 group than in the unvaccinated and hvVP2-vaccinated birds. Overall, the results indicated that paraffin-embedded tissue can be used as a source of genomic material for transgenic protein expression, that Pichia pastoris-expressed VP2 retains its immunogenicity, and that VP2 subunit vaccination conferred partial protection to challenge; it protected against clinical signs and death but not against IBDV infection.

Genetic characterization, pathogenicity, and protection studies with an avian adenovirus isolate associated with inclusion body hepatitis.

An avian adenovirus (AAV) was isolated from liver samples of two 2-wk-old broiler-breeder flocks obtained from grandparents vaccinated at 10 and 17 wks of age with an autogenous inactivated vaccine containing the European AAV 8 (8565 strain) and 11 (1047 strain) serotypes (AAV8/11 vaccine). Affected broiler-breeders exhibited clinical signs and macroscopic and microscopic lesions associated with inclusion body hepatitis (IBH). The isolated adenovirus, identified as Stanford, was molecularly characterized as European serotype 9. The pathogenicity of the Stanford strain was confirmed after inoculation of specific-pathogen-free (SPF) chickens at 1-7 days of age, causing 100% and 20% mortality, respectively. The level of protection against IBH was evaluated in two broiler-breeder progenies from AAV 8/11-vaccinated grandparent flocks and a commercial broiler flock by challenge at 1 or 7 days of age with the AAV 8 and 11 serotypes and/or the Stanford strain. The broiler-breeder progenies and the commercial broiler flock exhibited protection against IBH after challenge. No significant differences in mean body weights were observed at 3 wk of age in any of the evaluated groups. We conclude that broiler-breeder progenies from 30- to 50-wk-old grandparents vaccinated with the AAV 8/11 vaccine were adequately protected against challenge with the AAV 8 and 11 serotypes and the Stanford strain.

Intrinsic bursters increase the robustness of rhythm generation in an excitatory network.

The pre-Botzinger complex (pBC) is a vital subcircuit of the respiratory central pattern generator. Although the existence of neurons with pacemaker-like bursting properties in this network is not questioned, their role in network rhythmogenesis is unresolved. Modeling is ideally suited to address this debate because of the ease with which biophysical parameters of individual cells and network architecture can be manipulated. We modeled the parameter variability of experimental data from pBC bursting pacemaker and nonpacemaker neurons using a modified version of our previously developed pBC neuron and network models. To investigate the role of pacemakers in networkwide rhythmogenesis, we simulated networks of these neurons and varied the fraction of the population made up of pacemakers. For each number of pacemaker neurons, we varied the amount of tonic drive to the network and measured the frequency of synchronous networkwide bursting produced. Both excitatory networks with all-to-all coupling and sparsely connected networks were explored for several levels of synaptic coupling strength. Networks containing only nonpacemakers were able to produce networkwide bursting, but with a low probability of bursting and low input and output ranges. Our results indicate that inclusion of pacemakers in an excitatory network increases robustness of the network by more than tripling the input and output ranges compared with networks containing no pacemakers. The largest increase in dynamic range occurs when the number of pacemakers in the network is greater than 20% of the population. Experimental tests of our model predictions are proposed.

Effects of orally administered tetracycline on the intestinal community structure of chickens and on tet determinant carriage by commensal bacteria and Campylobacter jejuni.

There is a growing concern that antibiotic usage in animal production has selected for resistant food-borne bacteria. Since tetracyclines are common therapeutic antibiotics used in poultry production, we sought to evaluate the effects of oral administration on the resistance of poultry commensal bacteria and the intestinal bacterial community structure. The diversity indices calculated from terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA amplicons did not indicate significant changes in the cecal bacterial community in response to oxytetracycline. To evaluate its effects on cultivable commensals, Enterococcus spp., Escherichia coli, and Campylobacter spp. were isolated from the cecal droppings of broiler chickens. Enterococcus spp. and E. coli expressed tetracycline MICs of >8 microg/ml and harbored a variety of tet resistance determinants regardless of the tetracycline exposure history of the birds. The enterococcal isolates possessed tetM (61%), tetL (25.4%), and tetK (1.3%), as well as tetO (52.5%), the determinant known to confer a tetracycline resistance phenotype in Campylobacter jejuni. E. coli isolates harbored tetA (32.2%) or tetB (30.5%). Tetracycline MICs remained at <2 microg/ml for Campylobacter isolates before and after tetracycline treatment of the chickens, even though isolates expressing MICs of >16 mug/ml were commonly cultured from flocks that did not receive oxytetracycline. The results imply that complex ecological and genetic factors contribute to the prevalence of antibiotic resistance arising from resistance gene transfer in the production environment.

Genetic algorithm for optimization and specification of a neuron model.

We present a novel approach for neuron model specification using a Genetic Algorithm (GA) to develop simple firing neuron models consisting of a single compartment with one inward and one outward current. The GA not only chooses the model parameters, but also chooses the formulation of the ionic currents (i.e. single-variable, two-variable, instantaneous, or leak). The fitness function of the GA compares the frequency output of the GA generated models to an I-F curve of a nominal Morris-Lecar (ML) model. Initially, several different classes of models compete among the population. Eventually, the GA converges to a population containing only ML-type firing models with an instantaneous inward and single-variable outward current. Simulations where ML-type models are restricted from the population are also investigated. This GA approach allows the exploration of a universe of feasible model classes that is less constrained by model formulation assumptions than traditional parameter estimation approaches. While we use a simple model, this technique is scalable to much larger and more complex formulations.

Domain coarsening in electroconvection.

We report on experimental measurements of the growth of regular domains evolving from an irregular pattern in electroconvection. The late-time growth of the domains is consistent with the size of the domains scaling as t(n). We use two isotropic measurements of the domain size: the structure factor and the domain wall length. Measurements using the structure factor are consistent with t(1/5) growth. Measurements using the domain wall length are consistent with t(1/4) growth. One source of this discrepancy is the fact that the distribution of local wave numbers is approximately independent of the domain size. In addition, we measure the anisotropy of the growing domains.