Long-term evolution and transmission dynamics of swine influenza A virus

Swine influenza A viruses (SwIV) cause significant economic losses in animal husbandry as well as instances of human disease and occasionally give rise to human pandemics, including that caused by the H1N1/2009 virus. The lack of systematic and longitudinal influenza surveillance in pigs has hampered attempts to reconstruct the origins of this pandemic. Most existing swine data were derived from opportunistic samples collected from diseased pigs in disparate geographical regions, not from prospective studies in defined locations, hence the evolutionary and transmission dynamics of SwIV are poorly understood. Here we quantify the epidemiological, genetic and antigenic dynamics of SwIV in Hong Kong using a data set of more than 650 SwIV isolates and more than 800 swine sera from 12?years of systematic surveillance in this region, supplemented with data stretching back 34?years. Intercontinental virus movement has led to reassortment and lineage replacement, creating an antigenically and genetically diverse virus population whose dynamics are quantitatively different from those previously observed for human influenza viruses. Our findings indicate that increased antigenic drift is associated with reassortment events and offer insights into the emergence of influenza viruses with epidemic potential in swine and humans.     

Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease

Metabolomics studies hold promise for the discovery of pathways linked to disease processes. Cardiovascular disease (CVD) represents the leading cause of death and morbidity worldwide. Here we used a metabolomics approach to generate unbiased small-molecule metabolic profiles in plasma that predict risk for CVD. Three metabolites of the dietary lipid phosphatidylcholine--choline, trimethylamine N-oxide (TMAO) and betaine--were identified and then shown to predict risk for CVD in an independent large clinical cohort. Dietary supplementation of mice with choline, TMAO or betaine promoted upregulation of multiple macrophage scavenger receptors linked to atherosclerosis, and supplementation with choline or TMAO promoted atherosclerosis. Studies using germ-free mice confirmed a critical role for dietary choline and gut flora in TMAO production, augmented macrophage cholesterol accumulation and foam cell formation. Suppression of intestinal microflora in atherosclerosis-prone mice inhibited dietary-choline-enhanced atherosclerosis. Genetic variations controlling expression of flavin monooxygenases, an enzymatic source of TMAO, segregated with atherosclerosis in hyperlipidaemic mice. Discovery of a relationship between gut-flora-dependent metabolism of dietary phosphatidylcholine and CVD pathogenesis provides opportunities for the development of new diagnostic tests and therapeutic approaches for atherosclerotic heart disease.     

Forecasting with leading indicators revisited

Transfer function or distributed lag models are commonly used in forecasting. The stability of a constant‐coefficient transfer function model, however, may become an issue for many economic variables due in part to the recent advance in technology and improvement in efficiency in data collection and processing. In this paper, we propose a simple functional‐coefficient transfer function model that can accommodate the changing environment. A likelihood ratio statistic is used to test the stability of a traditional transfer function model. We investigate the performance of the test statistic in the finite sample case via simulation. Using some well‐known examples, we demonstrate clearly that the proposed functional‐coefficient model can substantially improve the accuracy of out‐of‐sample forecasts. In particular, our simple modification results in a 25% reduction in the mean squared errors of out‐of‐sample one‐step‐ahead forecasts for the gas‐furnace data of Box and Jenkins. Copyright © 2003 John Wiley & Sons, Ltd.     

A simple interspike interval analyzer for study of neuronal spike trains.

A simple, low cost interspike interval analyzer for the analysis of trains of nerve impulses is described. The analyzer is built with readily available integrated circuits and has been used to analyze spike trains in the lateral vestibular nucleus of cats.     

Statistical issues and approaches in endophenotype research

The endophenotype concept was initially proposed to enhance the power of genetic studies of complex disorders. It is closely related to the genetic component in a liability-threshold model; a perfect endophenotype should have a correlation of 1 with the genetic component of the liability to disease. In reality, a putative endophenotype is unlikely to be a perfect representation of the genetic component of disease liability. The magnitude of the correlation between a putative endophenotype and the genetic co...     

A direct plasma testosterone radioimmunoassay

Résumé On a développé und méthode simple pour déteminer sans chromatographie en colonne le testostérone du plasma. La purification a été faite par préextraction avec l'hexane. Un antisérum contre le testostérone a été produit chez des lapins inoculés avec des conjugués de testostérone-3-oxine et d'albumine de sérum bovin.     

Plastid differentiation on 6-azauracil media

Résumé Les mutants au locusm de l'Arabidopsis ne réussissent pas à former de chloroplastes normaux dans certaines conditions et montrent des activités plus hautes en synthèse de pyrimidines que le témoin. La nutrition aseptique par 6-azauracile, inhibiteur spécifique de cette voie métabolique, restaure la différenciatin de structure lamellaire dans la plupart de ces organites, mais aux concentrations élevées, apparaissent des chloroplastes morphologiquement déviants, quoique de fonction efficace.     

Dynamics of the amphibian middle ear.

Using laser speckle interferometry, we show that the directional information of acoustic signals is encoded in the motion of eardrum. Moreover, the frequency sensitivity of the auditory system is determined by the mechanical properties of the middle ear, which acts like a damped resonator.     

Induction of deoxyribonucleic acid degradation inEscherichia coli by ozone

Summary Cell survival and deoxyribonucleic acid (DNA) degradation were measured for wild-typeEscherichia coli B251 cells after exposure to different concentrations of ozone. The results show that extensive breakdown of DNA occurs after ozonation and that the extent of ozone-induced DNA degradation generally correlates with the colony-forming ability of the cells.We thank Dr M.J. d'Aoust for supplying laboratory facilities. This work was jointly sponsored by the National Research Council of Canada, the Ministère de l'Education du Québec, and funds from the Université de Montréal. One of us (C.H.) acknowledges a postgraduate scholarship from the NRC of Canada.