Interactions between Escherichia coli and allophane—I. Adsorption

Sorptive interactions between Escherichia coli (ATCC 11303B) and a purified allophane clay fraction were studied quantitatively using electronic particle counting and electrophoresis. Adsorption was influenced by pH and ions present at the allophane surface. These effects could be rationalized by considering changes in the net surface charge of the components. Electronic particle counting studies at pH 5.5 and above gave adsorption isotherms that obeyed single-term Langmuir kinetics. At pH 4.5, a more complex two-step isotherm was obtained, which was attributed to aggregation of unadsorbed cells by Al solubilized from the allophane surface.     

A questionnaire survey of the prevalence of scrapie in sheep in Britain

An anonymous, self-administered questionnaire has been used in two independent surveys to try to determine the prevalence of scrapie in the national sheep flock. The disease was recorded in 35 counties in England and Wales. About a third (26.5 and 37.3 percent) of respondents owning 100 or more sheep indicated that they had seen sheep with scrapie in their flocks. The incidences of clinical cases recorded in affected flocks in the two surveys were 0.5 and 1.1 cases/100 ewes/year. At present there is no control over the disposal of these animals. If as has been suggested, an increase in the prevalence of scrapie was a contributory factor in the emergence of bovine spongiform encephalopathy, it would seem logical that measures should be introduced to monitor the prevalence and incidence of scrapie and to control the disposal of clinical cases.     

Controlling microbial contamination on beef and lamb meat during processing

SUMMARY The microbiological quality of carcases, meat and environmental surfaces was evaluated in commercial boning rooms processing beef and lamb. There was considerable variation in the level of microbial contamination on both carcases and meat, with counts ranging from less than 20 to 10⁸/cm² on carcases and to 2 times 10⁷/cm² on meat. The level of microbial contamination on meat was influenced by the level of carcase contamination at boning and by the boning process itself. Carcase contamination was the major determinant of microbiological quality, as more than 70% of carcases had microbial counts greater than 10³/cm². Cutting boards were a major source for microbial dissemination during boning, particularly when carcase counts were less than 10³/cm². If carcases were heavily contaminated, the contamination of processing surfaces was irrelevant in determining microbial loads on meat. Where carcase contamination was at low to moderate levels, the contribution of the boning process to the contamination on meat assumed increased significance. Under these conditions, improved sanitation of cutting surfaces in the boning room resulted in a significant reduction in microbial contamination on the surface of meat. These results can form the basis for ensuring that improvements made in carcase management before boning, to improve microbiological quality, will be preserved through attention to cutting board hygiene during boning.     

Equine sarcoids: Bovine Papillomavirus type 1 transformed fibroblasts are sensitive to cisplatin and UVB induced apoptosis and show aberrant expression of p53

Bovine papillomavirus type 1 infects not only cattle but also equids and is a causative factor in the pathogenesis of commonly occurring equine sarcoid tumours. Whilst treatment of sarcoids is notoriously difficult, cisplatin has been shown to be one of the most effective treatment strategies for sarcoids. In this study we show that in equine fibroblasts, BPV-1 sensitises cells to cisplatin-induced and UVB-induced apoptosis, a known cofactor for papillomavirus associated disease, however BPV-1 transformed fibroblasts show increased clonogenic survival, which may potentially limit the therapeutic effects of repeated cisplatin treatment. Furthermore we show that BPV-1 increases p53 expression in sarcoid cell lines and p53 expression can be either nuclear or cytoplasmic. The mechanism and clinical significance of increase/abnormal p53 expression remains to be established.     

Development of a method for Bayesian nonparametric ROC analysis with application to an ELISA for Johne's disease in dairy cattle

Six hundred and sixty-eight dairy cattle were tested for Johne's disease using a direct-fecal real-time polymerase chain reaction (rt-PCR), fecal culture, and serum enzyme-linked immunosorbent assay (ELISA). Likelihood ratios (LRs) were estimated for five categories of sample-to-positive (S/P) values for the ELISA: <0.1, 0.1-0.249, 0.25-0.399, 0.4-0.999, > or =1.0. The statistical method assumed a single multinomial model for cross-classified rt-PCR, fecal culture results, and ELISA category strata. Conditional dependence between tests was investigated by the inclusion of all possible pairwise dependence terms. Sensitivity covariance between ELISA and fecal culture was estimated as 0.017. Estimates for the accuracy of the ELISA at the usual cutoff of 0.25S/P was 67.2% and 95.2% for sensitivity and specificity, respectively for a model that adjusted for the dependence between ELISA and fecal culture. The area under the receiver-operating characteristic (ROC) curve (95% probability interval) for the ELISA was 0.867 (0.796, 0.928). Point estimates for likelihood ratios (95% probability intervals) were 0.24 (0.11, 0.38), 1.52 (0.48, 3.27), 2.49 (0.31, 13.4), 6.33 (2.54, 16.5), and 103 (25.0, 2412) for the categories <0.1, 0.1-0.249, 0.25-0.399, 0.4-0.999, >/=1.0, respectively. Assumptions concerning the underlying distribution of test results for infected and uninfected animals were not necessary and this model can be employed for the general estimation of LRs and ROC curves in absence of knowledge concerning true disease status.     

Seroprevalence of and agroecological risk factors for Mycobacterium avium subspecies paratuberculosis and neospora caninum infection among adult beef cattle in cow-calf herds in Alberta, Canada

A province-wide cross-sectional seroprevalence and agroecological risk factor study of Mycobacterium avium subspecies paratuberculosis (MAP) and Neospora caninum (NC) infection among cattle in 100 cow-calf herds in Alberta was conducted. The seroprevalence of MAP in adult cattle was 1.5% across all herds. Using a widely accepted herd test cutpoint of 2 or more seropositive cows out of 30 animals tested, 7.9% of herds were estimated to be infected (95% confidence interval (CI): 2.3-23.4%). Seroprevalence of MAP differed by agroecological region; specifically, cattle and herds in areas with high soil pH (> 7.0), southern latitudes, and arid climates had a moderately reduced risk of infection (P < 0.10). Seroprevalence of NC infection was 9.7% among adult beef cattle province-wide--these levels also varied by agroecological region--with 91.0% of herds infected overall.     

Vertebral canal and spinal cord mensuration: a comparative study of its effect on lumbosacral myelography in the dachshund and German shepherd dog

One hundred noncontrast spinal radiographic studies followed by myelography were evaluated to compare vertebral canal size and spinal cord location and size in a chondrodystrophic breed (50 Dachshunds) with those variables in a nonchondrodystrophic breed (50 German Shepherd Dogs). Measurements were made of the sagittal diameter (height) of the vertebral canal, sagittal diameter (height) of the spinal cord, and transverse diameter (width) of the spinal cord in the lumbar and sacral regions. Differences were detected in the craniocaudal location of maximal vertebral canal height and maximal spinal cord height. The spinal cords in the Dachshunds terminated further caudally than those in the German Shepherd Dogs. Location of maximal spinal cord width was different between the breeds, consistent with the apparent, more caudal termination of the cord in the Dachshunds. The ratio of spinal cord to vetebral canal heights was notably greater in the Dachshunds than in the German Shepherd Dogs. These differences in vertebral canal and spinal cord mensuration may influence the choice of radiographic technique and its interpretation. Injection sites may be selected further cranially in German Shepherd Dogs (L4-5) than in Dachshunds (L5-6).