Risk factors for a positive meat juice ELISA result - an analysis of routine data from Britain

Data from the British Zoonoses Action Plan Salmonella Monitoring Programme (ZAP) and from quality assurance schemes for pig pforucers were combined to enable epidemiological analysis. Information concerning 105,631 samples from 1,806 farm were analysed using a multiple logistic regression model

Investigating the Past, Present and Future Responses of Shallap and Zongo Glaciers, Tropical Andes, to the El Niño Southern Oscillation

Tropical Andean glaciers are highly sensitive to climate change and are impacted by the El Niño Southern Oscillation (ENSO). However, glaciological data are scarce, meaning that there are substantial knowledge gaps in the response of Andean glaciers to future anthropogenic and ENSO forcing and these are crucial to address, as glaciers represent a key water source for downstream populations and ecosystems. Here we integrated data from glaciological field studies, remote sensing, statistical analysis and glacier modelling to analyse the response of two Andean glaciers (Zongo and Shallap) to ENSO and their potential sensitivity to a range of climate forcing scenarios. Both glaciers retreated and experienced increasingly negative mass balance between the 1990s and the 2010s and responded strongly and rapidly to contemporary ENSO forcing, although this relationship evolved over time. Sensitivity experiments demonstrate that Shallap and Zongo are highly sensitive to ENSO forcing scenarios and the combination of ENSO and climate warming can cause rapid ice loss under the most extreme scenarios. Results also demonstrate the strong sensitivity of both glaciers to changes in the equilibrium line altitude, whereby rapid ice loss occurred when melt extended into present-day accumulation areas

Permeation and metabolism of intermediates of the mandelate pathway in bacterium NCIB 8250

Many bacteria have a very wide metabolic versatility, generally in the form of convergent, inducible, catabolic pathways for the enzymic degradation of organic compounds. The regulation of these pathways is poorly understood. Theories on enzyme regulation are built on the operon model for the control of gene expression and the concept of allosteric control, of enzyme activity, while the permeability of the cell membrane has also been considered as a possible locus to mediate enzyme regulation. The mandelate pathway, of an Acinetobacter species, a soil organism known as bacterium NCIB 8250, is one defined unit in a convergent, inducible, catabolic sequence. The experimental work described in this thesis is concerned with the control of the enzymes converting L-mandelate and benzyl alcohol to catechol in bacterium NCIB 8250 and specifically with the role of permeation in the control mechanisms. A sensitive radiochemical assay was developed to measure the utilisation of mandelate, benzyl alcohol or benzoato during growth of bacterium NCIB 8250 in batch culture. An exponential growth curve was observed when either benzoate or benzyl alcohol was the sole source of carbon and energy. Growth in mandelate-salts medium was complex and involved the exhaustion of mandelate before the end of growth a transient accumulation of benzaldehyde and sub-sequent growth on excreted material. Growth in dual substrate' media was examined and certain cases of the preferential use of one substrate were observed. The utilisation of mandelate, use of one substrate were observed. The utilization of mandelate was supressed when benzoate, catechol or succinate was present, but not when benzyl alcohol was present. Suppression of the utilisation of benzyl alcohol in the presence of mandelate occurred after a delay, while benzoate suppressed benzyl alcohol utilization in cells preinduced to growth on benzoate but not in cells preinduced to growth on benzyl alcohol. No suppression of the utilization of benzoate was observed. The use of cell-free enzyme assays in the other intermediates showed that enzyme inhibitions were not the cause of the suppressions of substrate utilization. In whole cells, the utilization of mandelate, benzyl alcohol or benzoate was generally unaffected by other intermediates though catechol and succinate did have inhibitory effects (about 30%) of unknown origin. The utilization of mandelate in cells possessing the mandelate enzymes was not inhibited by benzoate, so suppression of mandelate utilization in the presence of benzoate was ascribed to repression of protein synthesis. At least some part of the effects of succinate and catechol in suppressing the utilization of mandelate was also ascribed to repression of protein synthesis. The enzymes for the utilization of benzyl alcohol were represented by L-mandelate, but no repression by benzoate catechol or succinate was detected. No repression of benzoate oxidase was detected. A radiochemical assay to measure very low quantities of intracellular aromatic intermediate was developed. A general permeability barrier to carbohydrate was exploited to estimate the intracellular water space and intracellular material was expressed as a concentration in that same water space. Varying degrees of permeability barriers to mandelate were displayed by cells without L-mandelate dehydrogenase. Rapid decarboxylation of mandelate was observed in induced wild type cells. An inducible mandelate transport system was therefore proposed. A high radiochemical reagent blank for benzyl alcohol prevented use of the radiochemical assay to study the entry of benzyl alcohol into cells in suspension. However, an inducible benzyl alcohol transport system was proposed on indirect evidence from growth experiments: benzoate suppressed the utilization of benzyl alcohol in cells preinduced to growth on benzoate without inhibition or repression in cells preinduced to growth on benzyl alcohol. No permeability barrier to benzoate itself was observed, and no substantial inhibition of the decarboxylation of benzoate by whole cells was detected in the presence of a wide range of analogues of benzoate. One of these compouds, p-fluoro-benzoato was decarbozylated by suspensions of cells induced to growth on benzoate. This decarboxylation was totally prevented by the presence of benzoate. Accordingly, a constitutive benzoate transport system was postulated. It thus appears that although a permeability barrier can prevent enzyme induction by preventing entry of inducer into the cell, repression of enzyme synthesis in the mandelate pathway of bacterium NCIB 8250 is a control at the level of the protein synthesis that is not mediated by an inhibition of transport. The possible relevance of the transport systems which have been postulated in this organism and the controls, in terms of multisensitive, end-product repression, are discussed

A transmission model for Salmonella in grower-finisher pigs

This paper presents a model describing the dynamic transmission of Salmonella Typhimurium between pigs on a typical, British pig grower-finisher farm. A modified Reed-Frost discrete-time model was used to estimate the probability of infection for susceptible pigs

Optimisation of pooled faecal samples for the isolation fo Salmonella from finisher pigs in GB.

Pooled pen floor faecal sampling represents a simple and non-invasive method to measure Salmonella infection in pigs. We extended an existing model of the sensitivity of detection of Salmonella in individual samples to create a mathematical model of the sensitivity of pooled sampling

ZAP: The role of routine surveillance data in understanding the geography and timing of Salmonella on UK pig farms.

The Zoonoses Action Plan (ZAP), at its inception m 2002, sought to reduce prevalence of Salmonella mfection 1n quality assured p1gs at slaughter by 25% within three years. Salmonella levels are monitored by Meat Juice ELISA tests on samples from individual pigs and aggregated to indicate farm-level Salmonella status. By combining the ZAP scheme and quality assurance scheme datasets we generated a large geographically referenced data set which allows us to investigate aspects of the spatial and temporal epidemiology of Salmonella on GB pig farms. We seek in this study to address two questions. First, is there evidence that Salmonella in GB pigs vanes seasonally? Secondly, do close farms tend to have similar levels of Salmonella? We suggest explanations for spatial and temporal effects where evidenced. Knowledge of seasons or GB regions which have atypically high Salmonella risk informs the design of control strategies

Use of spatiotemporal analysis of laboratory submission data to identify potential outbreaks of new or emerging diseases in cattle in Great Britain

BACKGROUND: New and emerging diseases of livestock may impact animal welfare, trade and public health. Early detection of outbreaks can reduce the impact of these diseases by triggering control measures that limit the number of cases that occur. The aim of this study was to investigate whether prospective spatiotemporal methods could be used to identify outbreaks of new and emerging diseases in scanning surveillance data. SaTScan was used to identify clusters of unusually high levels of submissions where a diagnosis could not be reached (DNR) using different probability models and baselines. The clusters detected were subjected to a further selection process to reduce the number of false positives and a more detailed epidemiological analysis to ascertain whether they were likely to represent real outbreaks. RESULTS: 187,925 submissions of clinical material from cattle were made to the Regional Laboratory of the Veterinary Laboratories Agency (VLA) between 2002 and 2007, and the results were stored on the VLA FarmFile database. 16,925 of these were classified as DNRs and included in the analyses. Variation in the number and proportion of DNRs was found between syndromes and regions, so a spatiotemporal analysis for each DNR syndrome was done. Six clusters were identified using the Bernoulli model after applying selection criteria (e.g. size of cluster). The further epidemiological analysis revealed that one of the systemic clusters could plausibly have been due to Johne's disease. The remainder were either due to misclassification or not consistent with a single diagnosis. CONCLUSIONS: Our analyses have demonstrated that spatiotemporal methods can be used to detect clusters of new or emerging diseases, identify clusters of known diseases that may not have been diagnosed and identify misclassification in the data, and highlighted the impact of data quality on the ability to detect outbreaks. Spatiotemporal methods should be used alongside current temporal methods for analysis of scanning surveillance data. These statistical analyses should be followed by further investigation of possible outbreaks to determine whether cases have common features suggesting that these are likely to represent real outbreaks, or whether issues with the collection or processing of information have resulted in false positives

Complete genome sequence of Parvibaculum lavamentivorans type strain (DS-1T)

Parvibaculum lavamentivorans DS-1T is the type species of the novel genus Parvibaculum in the novel family Rhodobiaceae (formerly Phyllobacteriaceae) of the order Rhizobiales of Alphaproteobacteria. Strain DS-1T is a non-pigmented, aerobic, heterotrophic bacterium and represents the first tier member of environmentally important bacterial communities that catalyze the complete degradation of synthetic laundry surfactants. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 3,914,745 bp long genome with its predicted 3,654 protein coding genes is the first completed genome sequence of the genus Parvibaculum, and the first genome sequence of a representative of the family Rhodobiaceae