Avian circovirus diseases: lessons for the study of PMWS

The diseases associated with psittacine beak and feather disease virus (BFDV), pigeon circovirus (PiCV) and goose circovirus (GoCV), which can be classified with porcine circovirus type 2 (PCV2) as members of the genus Circovirus of the family Circoviridae, have clinico-pathological features in common with post-weaning multisystemic wasting syndrome (PMWS), with which PCV2 infection is causally associated. Intracytoplasmic botryoid inclusions within macrophages and depletion of T and B lymphocytes are common histopathological features, and, in each case, affected animals usually exhibit ill-thrift and a predisposition to secondary infections, that is suggestive of an underlying immunosuppression. Although these avian diseases have been the subjects of relatively little research, their study can provide directly applicable lessons in the areas of diagnosis, epidemiology, pathogenesis and disease control for those charged with investigating PMWS. In keeping with its taxonomic separation as the only member of the genus Gyrovirus, the disease caused by chicken anaemia virus (CAV) differs histopathologically from the other circovirus-associated diseases. Most notably, the target cells of CAV have been identified as haemocytoblasts and precursor T lymphocytes, with lymphocyte depletion, which affects T cells only, occurring in cells directly infected with the virus. Nonetheless, CAV is the best-researched circovirus and provides excellent examples of both virus-induced immunosuppression and virus-virus interactions. The study of CAV-induced disease can therefore provide valuable, if less directly applicable lessons.     

Iridium-192 interstitial brachytherapy as adjunctive treatment for canine cutaneous mast cell tumors

Eleven dogs with cutaneous mast cell tumors (MCTs) were treated with surgery and iridium-192 ((192)Ir) interstitial brachytherapy. Minimum tumor doses ranged from 47.2 to 63.3 Gy. Treated tumors were classified as grade II (n=7) or III (n=4). Five dogs had recurrences with a median progression-free interval of 1391 days, and six dogs had no recurrence at a median follow-up time of 942 days. Acute adverse effects were well tolerated, and late effects were mild. One dog developed a second tumor of a different cell type in the radiation treatment field.     

Detection of pigeon circovirus in cloacal swabs: implications for diagnosis, epidemiology and control

Pigeon circovirus (picv) was detected in cloacal swab samples by means of a newly-developed, sensitive pcr. An initial investigation of 17 Belgian racing pigeons aged up to eight months showed that rates of detection of 88 per cent and above were achieved using samples of cloacal swab, blood and bursa of Fabricius. The sampling of 15 caged pigeons six times when they were from three to 31 weeks of age indicated that picv infections were more readily detected in cloacal swabs than in blood, and that the virus could be detected in cloacal swabs for longer periods after infection than in blood. picv infections were detected in cloacal swabs from 38 of 47 young pigeons aged from two to 31 weeks, from 12 racing lofts, which had clinical signs including diarrhoea and weight loss, regurgitation and respiratory signs. Samples from birds from two infected lofts indicated that picv could be detected in some birds for at least 27 weeks. Although nine of 14 pigeons aged from 32 to 45 weeks were virus-positive, picv was detected in only one of 18 adult pigeons that originated from four infected lofts.     

Television viewing behaviour and associations with food habits in different countries

OBJECTIVE: Several environmental factors influence adolescents' food habits and television (TV) viewing is thought to be one of these factors. The purpose of the present study was to describe sociodemographic differences in TV viewing and to examine associations of TV viewing with the consumption of sweets, soft drinks, fruit and vegetables in different countries. METHODS: Data were collected from 162,305 young people completing the 2001/02 Health Behaviour in School-Aged Children survey, a World Health Organization cross-national study on health and health behaviours among 11-, 13- and 15-year-old school pupils. Analyses of variance were used to examine sociodemographic differences in TV viewing and logistic regression analyses to examine associations between TV viewing and food habits. RESULTS: Large differences were found between countries in reported daily TV viewing time, from an average of 2.0 h in Switzerland to 3.7 h in Ukraine. The results indicate that those most likely to watch TV are boys, 13-year-olds and pupils of lower socio-economic status. Those who watched more TV were more likely to consume sweets and soft drinks on a daily basis and less likely to consume fruit and vegetables daily, although the latter associations were not so apparent among Central and Eastern European countries. CONCLUSIONS: Given the high TV viewing rates among adolescents and the association with less healthy food options, many young people are at increased risk of overweight or obesity. Interventions to modify TV viewing behaviour are needed. The findings underscore the importance of tackling socio-economic differences.     

Nanoparticle polymer composites: where two small worlds meet

The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous electrical, optical, or mechanical properties. Recent advances reveal routes to exploit both enthalpic and entropic interactions so as to direct the spatial distribution of nanoparticles and thereby control the macroscopic performance of the material. For example, by tailoring the particle coating and size, researchers have created self-healing materials for improved sustainability and self-corralling rods for photovoltaic applications. A challenge for future studies is to create hierarchically structured composites in which each sublayer contributes a distinct function to yield a mechanically integrated, multifunctional material.     

Storage of spatial information by the maintenance mechanism of LTP

Analogous to learning and memory storage, long-term potentiation (LTP) is divided into induction and maintenance phases. Testing the hypothesis that the mechanism of LTP maintenance stores information requires reversing this mechanism in vivo and finding out whether long-term stored information is lost. This was not previously possible. Recently however, persistent phosphorylation by the atypical protein kinase C isoform, protein kinase Mzeta (PKMz), has been found to maintain late LTP in hippocampal slices. Here we show that a cell-permeable PKMz inhibitor, injected in the rat hippocampus, both reverses LTP maintenance in vivo and produces persistent loss of 1-day-old spatial information. Thus, the mechanism maintaining LTP sustains spatial memory.     

Modeling exurban development near Washington, DC, USA: comparison of a pattern-based model and a spatially-explicit econometric model

The development of private rural lands can significantly fragment landscapes, with potentially negative consequences on ecosystem services. Models of land-use trends beyond the urban fringe are therefore useful for developing policy to manage these environmental effects. However, land-use change models have been primarily applied in urban environments, and it is unclear whether they can adequately predict exurban growth. This study compared the ability of two urban growth models to project exurban development in north-central Virginia and western Maryland over a 24-year period. Pattern-based urban growth models (such as SLEUTH) are widely used, but largely mimic patterns that emerge from historic conditions rather than allowing landowner decision-making to project change. In contrast, spatially-explicit econometric models (such as the complementary log?Clog hazard assessed in this study) model landowner choices as profit-maximizing behavior subject to market and regulatory constraints. We evaluated the two raster-based models by comparing model predictions to observed exurban conversion at pixel and county scales. The SLEUTH model was more successful at matching the total amount of new growth at the county scale than it was at the pixel scale, suggesting its most appropriate use in exurban areas is as a blunt instrument to forewarn potential coarse-scale losses of natural resources. The econometric model performed significantly better than SLEUTH at both scales, although it was not completely successful in fulfilling its promise of projecting changes that were sensitive to policy. The lack of significance of some policy variables may have resulted from insufficient variation in drivers over our study area or time period, but also suggests that drivers of land use change in exurban environments may differ from those identified for urban areas.