Structure of membranes: reaction of red blood cell membranes with phospholipase C

Treatment of human red blood cell membranes with phospholipase C releases 68 to 74 percent of the total membrane phosphorus into solution, through hydrolysis of membrane phospholipids to diglycerides and water-soluble phosphorylated amines. In spite of this drastic change, the membrane remains intact in phase microscopy, and the average protein conformation in the membranes, as determined by circular dichroism measurements in the ultraviolet, is unaffected. These results are readily explained by a model of membrane structure that is stabilized by hydrophobic interactions and in which the polar and ionic heads of lipids are on the outer surfaces of the membrane, in contact with the bulk aqueous phase and accessible to the action of phospholipase C.     

Treatment of septic common digital extensor tenosynovitis by complete resection in seven horses

OBJECTIVE: To describe and evaluate a technique for radical resection of the entire intrathecal component of the common digital extensor tendon (CDET) in horses. STUDY DESIGN: Prospective clinical study. ANIMALS OR SAMPLE POPULATION: Seven client-owned horses. METHODS: Seven horses with wounds that resulted in septic tenosynovitis of the CDET sheath were treated by complete surgical resection of the affected tendon and ablation of the tendon sheath; 5 had previous surgery that was unsuccessful. Time from initial injury to complete resection was 1-22 weeks. In 6 horses, the wound was closed primarily using a closed suction (4 horses), penrose (1), or passive open drainage system (1). In 1 horse, the surgical wound healed by second intention. All horses had postoperative bandaging, antibiotic administration, and physiotherapy. RESULTS: Surgical wounds healed primarily in 6 horses and by second intention in 1 horse. Follow-up (mean, 26.4 months; range, 18-38 months) was available for 6 horses; all returned to their athletic performance level without lameness or gait abnormality. CONCLUSIONS: Complete resection of the CDET was an effective surgical technique for management of chronic septic tenosynovitis. CLINICAL RELEVANCE: Horses with infection of the CDET and its sheath may be returned to long-term soundness without gait abnormality after radical resection.     

Memory decay and performance-related information bias in the reporting of scores by event riders

We used data from a case–control study investigating risk factors for horse falls in the cross-country phase of eventing in Great Britain (GB) to examine evidence for memory decay and information bias. Responses to two questions obtained by telephone for 173 cases and 521 controls were examined for evidence of differential reporting according to the respondent’s case–control status and performance in the dressage and cross-country phases of competitions. Information bias was found in the accuracy of reporting dressage penalty scores when analysed as a function of performance level (good/poor). Poor dressage performers were less likely to report accurate dressage scores than good performers. The accuracy of reporting dressage scores decreased as the time between the event and questionnaire completion increased, with no case–control interaction. Competitors who incurred cross-country jumping penalties at the event preceding the selected event reported their cross-country scores with less accuracy when compared with competitors who incurred no penalties. No information bias was found when the reporting of dressage and cross-country scores were analysed as a function of respondent category (case/control).     

Probability of introduction of exotic strains of bluetongue virus into the US and into California through importation of infected cattle

Strategies designed to minimize the probability of bluetongue virus (BTV) introduction to new areas should be based on a quantitative assessment of the probability of actually establishing the virus once it is introduced. The risk of introducing a new strain of bluetongue virus into a region depends on the number of viremic animals that enter and the competency of local vectors to transmit the virus. We used Monte Carlo simulation to model the probability of introducing BTV into California, USA, and the US through importation of cattle. Records of cattle and calf imports into California and the US were obtained, as was seroprevalence information from the exporting countries. A simulation model was constructed to evaluate the probability of importing either a viremic PCR-negative animal after 14-day quarantine, a c-ELISA BTV-antibody-negative animal after 28-day quarantine, or an untested viremic animal after 100-day quarantine into California and into the US. We found that for animals imported to the US, the simulated (best to worst scenarios) median percentage that tested positive for BTV-antibody ranged from 5.4 to 7.2%, while for the subset imported to California, the simulated median percentage that tested positive for BTV-antibody ranged from 20.9 to 78.9%. Using PCR, for animals imported to the US these values were 71.8–85.3%, and for those imported to California, the simulated median that test positive ranged from 74.3 to 92.4%. The probability that an imported animal was BTV-viremic is very low regardless of the scenario selected (median probability = 0.0%). The probability of introducing an exotic strain of BTV into California or the US by importing infected cattle was remote, and the current Office International des Epizooties (OIE) recommendation of either a final PCR test performed 14 days after entry into quarantine, a c-ELISA performed 28 days after entry into quarantine or a 100-day quarantine with no testing requirement was adequate to protect cattle in the US and California from an exotic strain of BTV.     

Race- and course-level risk factors for fatal distal limb fracture in racing Thoroughbreds

REASONS FOR PERFORMING STUDY: Considerable variation in the rates of equine fatality at different racecourses draws attention to probable risk factors at the level of course or race that might be partly responsible. Distal limb fractures are the most common cause of equine fatality on UK racecourses and identification of risk factors for such injuries and subsequent implementation of intervention strategies could significantly reduce the total number of racecourse fatalities. OBJECTIVES: To identify race- and course-level risk factors for fatal distal limb fracture in Thoroughbreds on UK racecourses. METHODS: A case-control study design was used. Case races were defined as those in which one or more horses sustained fatal fracture of the distal limb. Controls were selected in 2 different ways. Firstly, 3 races in which no fracture occurred were selected from all races of the same type held within 5 days of the case race (Analysis 1). Secondly, 3 control races were selected for each case race from all races of the same type held in the same year (Analysis 2). One hundred and nine cases were included in the study. Information about the race and the racecourses was collected from Computer Raceform. Conditional logistic regression was used to identify the relationship between a number of independent variables and the likelihood of fracture in a race. RESULTS: Longer races with a larger number of runners were more likely to contain a fracture. Firmer going and fewer days since the last race on the same course were associated with an increased risk of fracture. The going at the course at the previous race meeting was also associated with the likelihood of fracture. CONCLUSIONS: Modifications to the going on the day of a race and greater emphasis on ground maintenance between race meetings may have an impact on the risk of fatal distal limb fracture during racing. POTENTIAL RELEVANCE: Modification of risk factors such as the going and number of days since the last race meeting could reduce the number of equine fatalities on UK racecourses. The condition of the racecourse may be an important risk factor and future research should focus on the identification of course maintenance techniques that produce the safest possible racing surfaces.     

A statistical model for assessing sample size for bacterial colony selection: a case study of Escherichia coli and avian cellulitis.

A general problem for microbiologists is determining the number of phenotypically similar colonies growing on an agar plate that must be analyzed in order to be confident of identifying all of the different strains present in the sample. If a specified number of colonies is picked from a plate on which the number of unique strains of bacteria is unknown, assigning a probability of correctly identifying all of the strains present on the plate is not a simple task. With Escherichia coli of avian cellulitis origin as a case study, a statistical model was designed that would delineate sample sizes for efficient and consistent identification of all the strains of phenotypically similar bacteria in a clinical sample. This model enables the microbiologist to calculate the probability that all of the strains contained within the sample are correctly identified and to generate probability-based sample sizes for colony identification. The probability of cellulitis lesions containing a single strain of E. coli was 95.4%. If one E. coli strain is observed out of three colonies randomly selected from a future agar plate, the probability is 98.8% that only one strain is on the plate. These results are specific for this cellulitis E. coli scenario. For systems in which the number of bacterial strains per sample is variable, this model provides a quantitative means by which sample sizes can be determined.     

Systemic Immunosuppression by Methylprednisolone and Pregnancy Rates in Goats Undergoing the Transfer of Cloned Embryos

The presence of the zona pellucida has been perceived as a requirement for the oviductal transfer of cloned embryos at early stages of development while protecting the embryo from an immune system response. We hypothesized that steroid hormone therapy could reduce a potential cellular immune response after the transfer of zona‐free cloned embryos into the oviduct of recipient female goats. In Experiment 1, seven does were used to study the systemic immunosuppressant effect of the methylprednisolone administration (for 3 days) on blood cell counts. Whole blood was collected prior to treatment with methyprednisolone and then on Days 1, 2, 3, 4, 7, 14, 21 and 28 after the first dose of methylprednisolone for the analysis of haematological parameters. Methylprednisolone treatment significantly reduced circulating white blood cells and neutrophils in comparison with pre‐treatment levels, demonstrating a systemic immunosuppressant effect. In Experiment 2, a group of 58 does were used as recipient females to study the effect of administration of methylprednisolone for 3 days on the establishment of pregnancies after the transfer of zona‐free cloned embryos into the oviducts. No effects on pregnancy rates on Day 30 were observed regarding the distinct treatment groups (control vs. methylprednisolone), the source of oocytes (in vivo‐ vs in vitro‐matured) or the presence or absence of the zona pellucida in embryos. In summary, methylprednisolone was effective at inducing a systemic immunosuppressed state in goats, but the treatment prior to embryo transfer did not affect pregnancy rates. Moreover, pregnancy rates were similar between zona‐free and zona‐intact goat cloned embryos.     

Sexual Precocity of Nellore Bulls that are Offspring of Super Precocious,Precocious and Normal Cows in Extensive Farming Conditions

The objective of this work was to verify that mothers classified as super precocious (M1) and precocious (M2) produce more precocious bulls than females classified as normal (M3). This study included 21 186 animals with an average age of 21.29 ± 1.77 months that underwent a breeding soundness evaluation from 1999 to 2008. Of these animals, 2019, 6059 and 13 108 were offspring of M1, M2 and M3 females, respectively. In the breeding soundness examination, the animals were classified as sound for reproduction, sound under a natural mating regime, unsound for reproduction and discarded. To compare the averages obtained for each category of mother within the individual breeding soundness classes, a chi‐square test with a 5% error probability was used, considering the effects of year and month of birth and farm. For the three classes of mothers (M1, M2 and M3), 67.26, 67.22 and 64.16% of bull calves were considered sound for reproduction and 19.71, 19.46 and 21.90% were considered unsound for reproduction, respectively. There was no difference in the frequency of animals that were sound for reproduction under the natural breeding regime between the three classes of mothers (8.87, 9.31 and 9.19%, respectively). There was a difference between the numbers of precocious and normal females that were discarded, with frequencies of 4.01 and 4.75%, respectively (p < 0.05). There were differences in year and month of birth and farm between super precocious and precocious cows in relation to the breeding soundness classification of the animals. It was concluded that the bull offspring of super precocious and precocious cows presented a higher percentage of approval in the breeding soundness examination than the bull offspring of normal cows, demonstrating that the selection for precocity of females has contributed to an increase in the sexual precocity of the herd in relation to the sexual maturity of bulls.