Liver torsion and associated bacterial peritonitis in a dog.

A Malamute was examined for acute abdominal pain and collapse. Radiographs of the abdomen showed a pneumoabdomen, and a lucent mass in the region of the liver. Abdominocentesis yielded an inflammatory exudate with bacteria compatible with a Bacillus or a Clostridium sp. A quadrate lobe torsion was found at postmortem.     

Isolation of respiratory bovine coronavirus, other cytocidal viruses, and Pasteurella spp from cattle involved in two natural outbreaks of shipping fever

OBJECTIVE: To identify cytocidal viruses and Pasteurella spp that could be isolated from cattle involved in 2 natural outbreaks of shipping fever. ANIMALS: 105 and 120 castrated male 4- to 8-month-old feedlot cattle involved in 1997 and 1998 outbreaks, respectively. PROCEDURES: Nasal swab specimens and blood samples were collected, and cattle were vaccinated on arrival at an order-buyer barn from 4 local auction houses. Four days later, they were transported to a feedlot, and additional nasal swab specimens and blood samples were collected. Nasal swab specimens were submitted for virus isolation and bacterial culture; blood samples were submitted for measurement of respiratory bovine coronavirus (RBCV) hemagglutinin inhibition titers. RESULTS: 93 of 105 cattle and 106 of 120 cattle developed signs of respiratory tract disease during 1997 and 1998, respectively, and RBCV was isolated from 81 and 89 sick cattle, respectively, while at the order-buyer's barn or the day after arrival at the feedlot. During the 1997 outbreak, bovine herpesvirus 1 was isolated from 2 cattle at the order-buyer's barn and from 5 cattle 7 and 14 days after arrival at the feedlot, and parainfluenza virus 3 was isolated from 4 cattle 14 days after arrival at the feedlot. During the 1998 outbreak, bovine herpesvirus 1 was isolated from 2 cattle at the order-buyer's barn and on arrival at the feedlot and from 5 cattle 7 and 14 days after arrival at the feedlot, and parainfluenza virus 3 was isolated from 1 animal the day of, and from 18 cattle 7 and 14 days after, arrival at the feedlot. Pasteurella spp was cultured from 4 and 6 cattle at the order-buyer's barn and from 92 and 72 cattle on arrival at the feedlot during the 1997 and 1998 outbreaks, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that RBCV may play a causative role in outbreaks of shipping fever in cattle. More than 80% of the sick cattle shed RBCV at the beginning of 2 outbreaks when the Pasteurella spp infection rate was low.     

Effects of infection with parainfluenza-3 virus and infectious bovine rhinotracheitis virus on neutrophil functions in calves

Calves were challenge exposed in separate experiments with parainfluenza-3 (PI-3) virus or infectious bovine rhinotracheitis (IBR) virus. Blood neutrophils were assayed for functional activity every other day for at least 3 weeks by random migration, Staphylococcus aureus ingestion, antibody-dependent cell-mediated cytotoxicity, cytochrome-c reduction, iodination, and native chemiluminescence. Exposure to PI-3 virus resulted in a brief febrile response and no other clinical signs. Alterations in total or differential WBC counts were not detected. Chemiluminescence and iodination activities were reduced from activities before exposure. Exposure to IBR virus resulted in mild clinical signs and a febrile response of several days' duration. Total WBC and mononuclear cell counts were reduced. Random migration was reduced, whereas S aureus ingestion was enhanced. We concluded that infection of calves with IBR virus and PI-3 virus might directly or indirectly result in alterations of neutrophil function. The functional alterations apparently are different for each virus. These virus-induced alterations in neutrophil function might predispose calves to secondary bacterial pneumonia.     

Benchmark stem densities for forests and woodlands in south-eastern Australia under conditions of relatively little modification by humans since European settlement

Estimates of forest and woodland structure prior to major periods of modification (e.g. prior to European settlement) are routinely used to inform decisions relating to biodiversity conservation, silviculture and carbon sequestration potential in natural forests and woodlands. The techniques used to derive these estimates often demand that data be collected from specific geographic locations (e.g. locations for which historic survey records exist, where pollen accumulates, or where there is little modification by humans since European settlement) and therefore are often inherently biased. In this study we predicted numbers of trees by diameter class for several widespread forest and woodland types in south-eastern Australia under conditions of relatively little modification by humans since European settlement. To do this we fitted Generalised Additive Models (GAMs) separately to counts of stems in eight diameter classes from 495 plots using explanatory variables representing human modification, environmental variation and natural disturbances. We predicted stem densities under conditions of relatively little modification by humans since European settlement from these models by holding the significant explanatory variables representing modification by humans at minimum observed values. We compared these predictions with published estimates of pre-European stem densities and estimates that we derived for stands at theoretical equilibrium using the quotient of diminution (q). Our mean predictions were broadly comparable with estimates derived from both of these sources; however, we appeared to over-estimate numbers of stems in the smaller diameter classes for some vegetation alliances. A key outcome of this research – and rarely reflected in other techniques used to predict pre-European forest structure – was the amount of variation in stem numbers even within a single diameter class and vegetation alliance. For example, in the white box vegetation alliance, flat parts of the landscape supported 5 times the number of large trees (>80 cm DBH) found on upper slopes under conditions of relatively little modification by humans since European settlement. Our results therefore suggest that these forests and woodlands are more structurally heterogeneous than typically reflected in pre-European estimates and vegetation alliance should not be the unit for managing these stands. The methodology we present is applicable in many forests where the objective is to predict forest structure under conditions of relatively little modification by humans.     

Rapidly quantifying reference conditions in modified landscapes

Reference conditions remain widely used as a benchmark for ecosystem management, but there remains conjecture about the definition of the reference state. Many techniques used to predict reference conditions are difficult to apply operationally because they are resource-intensive, subjective, or applicable for a limited suite of environmental variables or over a narrow range of environmental variation. We defined the reference state as variation in native vegetation exhibiting relatively little evidence of modification by humans since European settlement. Using data from 462 sites supporting native vegetation in a fragmented landscape in south-eastern Australia, we demonstrated a relatively quick and cost-effective way of objectively predicting reference conditions for various surrogates of biodiversity. We predicted reference values for several variables that are used as biodiversity surrogates (i.e., tree densities by diameter class, trees with hollows, tree regeneration, trees with mistletoe, fallen timber, vegetation cover by vertical stratum, litter cover, cryptogam cover and native plant species richness) using generalized additive models (GAMs) fitted with predictors representing measures of human modification since European settlement (exotic plant cover, number of stumps, evidence of firewood collection, evidence of rabbits, evidence of recent grazing by stock, surrounding land use) and measures of environmental variation (floristic composition, mean annual precipitation, mean annual temperature, solar insolation, aspect, slope). Reference values for each response variable were predicted from these models by holding the significant explanatory variables representing modification since European settlement at their minimum observed values, that is, our definition of the reference state. We demonstrated the importance of independently evaluating predictions of this type using generic ecological models and estimates of reference conditions derived from other sources.     

Identification of low productivity sites for European larch (Larix decidua Miller) in Maine,USA

As silvicultural capital becomes limited, allocation of funds to high quality sites becomes critical and sites with low productivity potential should be avoided. Data collected from 31 plots located in 12 plantations established between 1930 and 1982 throughout central Maine were used to develop a soil-based rule to identify sites having a low productivity potential for European larch in Maine, thereby removing them from consideration for plantation establishment. Stepwise regression and discriminant analyses identified several variables that were associated with site index at an index age of 20 years breast height (SI₂₀): solum thickness, B horizon clay content, and B horizon exchangeable K. Using these variables, a classification rule was developed to classify sites into 2 categories (poor, average SI₂₀=14.7 m; and good, average SI₂₀=17.7 m). Cross-validation demonstrated that the classification functions correctly identified 88% of the poor sites and 81% of the good sites.     

Relation between work and phosphate metabolite in the in vivo paced mammalian heart

Nuclear magnetic resonance (NMR) spectroscopy was used to monitor, on a beat-to-beat basis, the concentration of creatine phosphate and adenosine triphosphate during alterations in the work output of canine hearts in vivo. Over a wide range of rate-pressure products (5,000 to 25,000 mmHg/min), the relative amounts of creatine phosphate and adenosine triphosphate within the heart remained constant. The relative concentration of free adenosine diphosphate was calculated under the reasonable assumption that the creatine kinase-catalyzed reaction is near equilibrium in this tissue. The free concentration of adenosine diphosphate also did not change over this range of rate-pressure products. The data demonstrate that the concentration of these compounds is highly regulated in vivo and suggest that factors other than their concentration may be involved in the modulation of steady-state myocardial work output with oxygen consumption.     

In vivo function and membrane binding properties are correlated for Escherichia coli lamB signal peptides

Wild-type and pseudorevertant signal peptides of the lamB gene product of Escherichia coli interact with lipid systems whereas a nonfunctional deletion mutant signal peptide does not. This conclusion is based on interaction of synthetic signal peptides with a lipid monolayer-water surface, conformational changes induced by presence of lipid vesicles in an aqueous solution of signal peptide, and capacities of the peptides to promote vesicle aggregation. Analysis of the signal sequences and previous conformational studies suggest that these lipid interaction properties may be attributable to the tendency of the functional signal peptides to adopt alpha-helical conformations. Although the possibility of direct interaction between the signal peptide and membrane lipids during protein secretion is controversial, the results suggest that conformationally related amphiphilicity and consequent membrane affinity of signal sequences are important for function in vivo.     

Early generation selection for yield and breadmaking quality of hard red spring wheat (Triticum aestivum L. em thell.)

Summary Evaluation of the effect of selection in 3 different F₃ populations of hard red spring wheat was achieved for yield and breadmaking quality parameters by examining the subsequent performance of F₃ selections as populations of F₅ lines. For baking absorption the mean performance of the F₅ populations was positively related to the performance of the F₃ selections in each of the 3 population-years. A significant relationship between the performance in F₃ and in F₅ was not obtained in any of the 3 years for bushel weight, flour ash, remix loaf volume, farinograph mixing tolerance index or for flour color grade. A high positive relationship between performance in F₃ and F₅ was found in two out of three years for protein content, flour protein content and 1,000-kernel weight. Predictive ability for sedimentation value, flour yield, farinograph development time and blend loaf volume was inconsistent for different population-years.A positive relationship between the yield of F₃ plots and the mean yield of F₅ populations was found in only 1 year. In the other 2 years the relationship between F₃ and F₅ yields ranged from nonsignificant to low, negative and significant. The latter results were possibly related to the relatively narrow high yielding range of the total F₃ variability for yield which was sampled in each of those years. In all 3 population-years the highest yielding F₅ populations were derived from F₃ lines which were high yielding on a plot basis and also very high yielding relative to the yield of their adjacent control in the F₃ nursery.Broad sense heritabilities calculated for the F₅ generation support the thesis that selection between F₃-derived populations would be a worthwhile plant breeding procedure for many of the breadmaking quality parameters.Contribution number 267 of the Department of Plant Science, University of Manitoba.