In vitro validation of a Pitot-based flow meter for the measurement of respiratory volume and flow in large animal anaesthesia

Objective  To remodel and validate commercially available monitors and their Pitot tube-based flow sensors for use in large animals, using in vitro techniques.
Study design  Prospective, in vitro experiment.
Methods  Both the original and the remodelled sensor were studied with a reference flow generator. Measurements were taken of the static flow-pressure relationship and linearity of the flow signal. Sensor airway resistance was calculated. Following recalibration of the host monitor, volumes ranging from 1 to 7 L were generated by a calibration syringe, and bias and precision of spirometric volume was determined. Where manual recalibration was not available, a conversion factor for volume measurement was determined. The influence of gas composition mixture and peak flow on the conversion factor was studied.
Results  Both the original and the remodelled sensor showed similar static flow–pressure relationships and linearity of the flow signal. Mean bias (%) of displayed values compared with the reference volume of 3, 5 and 7 L varied between −0.4% and +2.4%, and this was significantly smaller than that for 1 L (4.8% to +5.0%). Conversion factors for 3, 5 and 7 L were very similar (mean 6.00 ± 0.2, range 5.91–6.06) and were not significantly influenced by the gas mixture used. Increasing peak flow caused a small decrease in the conversion factor. Volume measurement error and conversion factors for inspiration and expiration were close to identity.
Conclusion  The combination of the host monitor with the remodelled flow sensor allowed accurate in vitro measurement of flows and volumes in a range expected during large animal anaesthesia.
Clinical relevance  This combination has potential as a reliable spirometric monitor for use during large animal anaesthesia.     

Managing successional trajectories in alien-dominated, novel ecosystems by facilitating seedling regeneration: A case study

Managing novel ecosystems that emerge after strong anthropogenic disturbance and the spread of alien species poses complex problems. As a case example, we discuss efforts on the tropical oceanic island Mahé (Seychelles) to promote the regeneration of native trees in tropical secondary forest dominated by the invasive tree Cinnamomum verum (true cinnamon).We monitored the growth of transplanted and self-sown native and alien tree seedlings in both artificially created forest gaps and in the understorey of closed forest. In the understorey, native species survived but grew very slowly, indicating that any recovery of native tree populations would also be very slow. In larger gaps, seedlings of certain invasive species grew particularly fast, suggesting that these species would rapidly dominate. Nutrient addition had only a minor positive effect on seedling growth, especially in the understorey.Although neither closed canopy conditions nor large gaps are conducive to the recovery of native seedlings, our data indicate that intermediate levels of canopy disturbance, i.e. those attained by felling one or a few trees, provide a combination of below- and aboveground resource limitation of seedling growth that may favour native species over invasive species. Based on these findings, we propose a strategy for restoring native vegetation that entails making small gaps in cinnamon-dominated forest and planting them with native tree species.This study illustrates how management strategies can be improved by combining insights gained from past interventions with the results of field and greenhouse experiments.     

Highly sensitive antigen detection procedures for the diagnosis of infectious bovine rhinotracheitis: amplified ELISA and reverse passive haemagglutination

The sensitivity of an enzyme-linked immunosorbent assay (ELISA) for the detection of bovid herpesvirus 1 antigen was increased by up to 50-fold using the biotin-avidin interaction to amplify the reaction, when compared with a simple sandwich ELISA. An alternative immunoassay, reverse passive haemagglutination (RPHA), had a similar sensitivity to the amplified ELISA, and was technically simpler to perform. Both the amplified ELISA and the RPHA could detect viral antigen in the nasal secretions of calves undergoing experimental primary infection with the virus from Day 3 to Day 7 after inoculation. Neither assay was as sensitive as virus isolation in cell culture and they failed to detect antigen in virus-positive samples from the calves from 8 days after inoculation, and from vaccinated calves undergoing challenge infection.     

Effects of Commercial Hydrolytic Enzyme Additives on Japanese‐Style Sponge and Dough Bread Properties and Processing Characteristics

The effects of increasing levels of eight commercial fungal enzymes enriched in four types of activity (α‐amylase, protease, xylanase, or cellulase) on Japanese‐style sponge and dough bread quality and processing characteristics have been studied using a Canadian red spring wheat straight‐grade flour. At optimum levels, the enriched α‐amylases, xylanases, and cellulases increased loaf volume and bread score and reduced crumb firmness, while the proteases only reduced crumb firmness. For α‐amylases, xylanases, and cellulases, optimum levels for crumb firmness were obtained at higher levels of addition than for loaf volume and bread score. At high levels of addition, all four enriched enzyme types reduced loaf volume and bread score and increased crumb firmness relative to optimum levels, with the proteases showing the most dramatic effects. α‐Amylases and cellulases had little impact on dough mixing requirements, while xylanases increased and proteases greatly reduced mixing requirements. All enzymes at optimum levels reduced sheeting work requirements, resulting in softer more pliable dough. Optimum bread properties for α‐amylases, xylanases, and cellulases were attained within a relatively narrow range of dough sheeting work values. This similarity in response suggests a dominant common nonspecific mechanism for their improver action, which is most likely related to water release and the resulting impact on physical dough properties.