Association of a Pasteurella haemolytica-like organism with enteritis in swine.   总被引：1，自引：0，他引：1  

B G McLaughlin  S C Greer  M M Chengappa  S Singh  R L Maddux  W L Kadel  P S McLaughlin 《Journal of veterinary diagnostic investigation》1991,3(4):324-327

A Pasteurella haemolytica-like organism was isolated from the intestines of 28 swine with clinical, gross, or microscopic evidence of enteritis. In 15 cases, other known enteric pathogens were also demonstrated, and in 13 cases, no other pathogens were detected. The mean age of affected animals was 44 days. Most of the animals had clinical evidence of diarrhea. Gross enteric lesions were present in 17 of 21 cases. Microscopic lesions were present in 24 of 26 cases. A diffuse or segmental moderate to severe necrotizing enteritis was the most common lesion in cases in which only the Pasteurella haemolytica-like organism was isolated. Biochemical tests gave results consistent with Pasteurella haemolytica, and 5 of 15 isolates met criteria for biotype A. Negative results were found with an indirect haemagglutination procedure for P. haemolytica.  相似文献   

Mastitis control: the use of electronic cell counting methods     

J K Pearson  D O Greer  B K Spence 《The Veterinary record》1972,90(17):485-486

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N-acetyl-beta-D-glucosaminidase test for screening milk samples for subclinical mastitis.   总被引：2，自引：0，他引：2  

H J Ball  D Greer 《The Veterinary record》1991,129(23):507-509

The use of the N-acetyl-beta-D-glucosaminidase (NAGase) test for detecting subclinical mastitis was investigated in surveys of milk samples from 20 farms. A milk sample was considered to be mastitic if it had a milk cell count above 400,000 cells/ml, and the NAGase test results were graded accordingly. The test gave an average of 16.6 per cent false positives and 2.0 per cent false negatives per herd. It was concluded that the NAGase test could be used as a rapid screening method for selecting suspect samples for further analysis by standard methods.  相似文献   

Streptococcus agalactiae in dairy heards. Its incidence and relationship to cell count and inhibitory substance levels in bulk milk   总被引：1，自引：0，他引：1  

D O Greer  J K Pearson 《The British veterinary journal》1973,129(6):544-554

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Evaluation of a technique to measure heart rate variability in anaesthetised cats     

Kuan Hua Khor  Ian A. Shiels  Fiona E. Campbell  Ristan M. Greer  Annie Rose  Paul C. Mills 《Veterinary journal (London, England : 1997)》2014,199(2):229-235

Analysis of heart rate (HR) and heart rate variability (HRV) are powerful tools to investigate cardiac diseases, but current methods, including 24-h Holter monitoring, can be cumbersome and may be compromised by movement artefact. A commercially available data capture and analysis system was used in anaesthetised healthy cats to measure HR and HRV during pharmacological manipulation of HR. Seven healthy cats were subjected to a randomised crossover study design with a 7 day washout period between two treatment groups, placebo and atenolol (1 mg/kg, IV), with the efficacy of atenolol to inhibit β₁ adrenoreceptors challenged by epinephrine. Statistical significance for the epinephrine challenge was set at P < 0.0027 (Holm–Bonferroni correction), whereas a level of significance of P < 0.05 was set for other variables.Analysis of the continuous electrocardiography (ECG) recordings showed that epinephrine challenge increased HR in the placebo group (P = 0.0003) but not in the atenolol group. The change in HR was greater in the placebo group than in the atenolol group (P = 0.0004). Therefore, compared to cats pre-treated with placebo, pre-treatment with atenolol significantly antagonised the tachycardia while not significantly affecting HRV. The increased HR in the placebo group following epinephrine challenge was consistent with a shift of the sympathovagal balance towards a predominantly sympathetic tone. However, the small (but not significant at the critical value) decrease in the normalised high-frequency component (HF_norm) in both groups of cats suggested that epinephrine induced a parasympathetic withdrawal in addition to sympathetic enhancement (increased normalised low frequency component or LF_norm). In conclusion, this model is a highly sensitive and repeatable model to investigate HRV in anaesthetised cats that would be useful in the laboratory setting for short-term investigation of cardiovascular disease and subtle responses to pharmacological agents in this species.  相似文献   

Chemistry. Enhanced: a view of unusual peroxides     

Greer A 《Science (New York, N.Y.)》2003,302(5643):235-236

Chemical processes involving oxygen can lead to unstable peroxide molecules such as three-membered ring dioxiranes. In his Perspective, Greer describes the stability of a variety of heteroatom-containing dioxiranes and the tools used to characterize unstable peroxides species. He highlights the report by Ho et al., who have used low-temperature nuclear magnetic resonance to obtain direct evidence for dioxirane intermediates. The method may also be applicable to biological systems in which peroxides have been implicated.  相似文献   

Polymorphs of Alumina Predicted by First Principles: Putting Pressure on the Ruby Pressure Scale     

KT Thomson  RM Wentzcovitch  MST Bukowinski 《Science (New York, N.Y.)》1996,274(5294):1880-1882

Fully optimized quantum mechanical calculations indicate that Al2O3 transforms from the corundum structure to the as yet unobserved Rh2O3 (II) structure at about 78 gigapascals, and it further transforms to Pbnm-perovskite structure at 223 gigapascals. The predicted x-ray spectrum of the Rh2O3 (II) structure is similar to that of the corundum structure, suggesting that the Rh2O3 (II) structure could go undetected in high-pressure x-ray measurements. It is therefore possible that the ruby (Cr3+-doped corundum) fluorescence pressure scale is sensitive to the thermal history of the ruby chips in a given experiment.  相似文献   

Composition of interstitial waters of marine sediments: temperature of squeezing effect     

Bischoff JL  Greer RE  Luistro AO 《Science (New York, N.Y.)》1970,167(3922):1245-1246

Warmeling of samples of marine sediments to room temperatures prior to the extraction of interstitial water accounts for the apparent enrichments of potassium ion (13.3 percent) and chloride ion (1.4 percent) and depletions of magnesium ion (2.5 percent) and calcium ion (4.9 percent). These differences are the result of changes in ion-exchange selectivity as a function of temperature.  相似文献   

An Economics Approach to Hard Computational Problems     

BA Huberman  RM Lukose  T Hogg 《Science (New York, N.Y.)》1997,275(5296):51-54

A general method for combining existing algorithms into new programs that are unequivocally preferable to any of the component algorithms is presented. This method, based on notions of risk in economics, offers a computational portfolio design procedure that can be used for a wide range of problems. Tested by solving a canonical NP-complete problem, the method can be used for problems ranging from the combinatorics of DNA sequencing to the completion of tasks in environments with resource contention, such as the World Wide Web.  相似文献   

Classification of porcine reproductive and respiratory syndrome virus in Ontario using Bayesian phylogenetics and assessment of temporal trends     

Dylan John Melmer  Robert Friendship  Terri L. O&#x;Sullivan  Amy L. Greer  Dinko Novosel  Davor Ojki&#x;  Zvonimir Poljak 《Canadian journal of veterinary research》2021,85(2):83

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most important swine viruses globally, including in Ontario, Canada. Understanding the evolution and relation of the various PRRSV genotypes in Ontario can provide insight into the epidemiology of the virus. The objectives of this study were to i) describe the variability of PRRSV genotypes in Ontario swine herds, and ii) evaluate possible groupings based on PRRSV genomic data. Virus open reading frame 5 (ORF-5) sequences collected from 2010 to 2018 were obtained from the Animal Health Laboratory, University of Guelph and Bayesian phylogenetic models were created from these. The PRRSV population of Ontario was then categorized into 10 distinct clades. Model comparisons indicated that the model with a constant population assumption fit the data best, which suggests that the net change in the PRRS virus variation of the entire population over the last decade was low. Nonetheless, viruses grouped into individual clades showed temporal clustering during distinct time intervals of the entire study period (P < 0.01).  相似文献