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71.
Summary The aim of the present study was to investigate whether the resistance of beech foliage(Fagus sylvatica) against oxidative stress was affected by soil quality, nitrogen or CO2 fertilisation, or lachnid infestation(Phyllaphis fagi). For this purpose young beech trees were grown for four years in reconstructed calcareous or acidic forest soils in open
top chambers under ambient or elevated CO2 concentrations with two levels of nitrogen fertilisation. At harvest lachnid colonisation was observed, preferentially on
leaves from trees in calcareous soil and on leaves from trees fertilised with the high nitrogen level. General leaf characteristics
such as pigment concentrations, dry mass, and leaf mass ber area were not affected by the soil type, nitrogen fertilisation
or CO2 regime. Leaves colonised with lachnids displayed slightly increased leaf mass per area. When the stress resistance was challenged
by exposure to paraquat — a herbicide inducing oxidative stress — leaves from trees grown on calcareous soil maintained significantly
longer membrane integrity and, thus, were better protected against stress than leaves from trees on acidic soil. Other experimental
variables had negligible or no effects on the resistance against oxidative stress.
相似文献
72.
As forests age, their structure and productivity change, yet in some cases, annual rates of water loss remain unchanged. To identify mechanisms that might explain such observations, and to determine if widely different age classes of forests differ functionally, we examined young (Y, approximately 25 years), mature (M, approximately 90 years) and old (O, approximately 250 years) ponderosa pine (Pinus ponderosa Dougl. ex P. Laws.) stands growing in a drought-prone region of central Oregon. Although the stands differed in tree leaf area index (LAIT) (Y = 0.9, M = 2.8, O = 2.1), cumulative tree transpiration measured by sap flow did not differ substantially during the growing season (100-112 mm). Yet when water was readily available, transpiration per unit leaf area of the youngest trees was about three times that of M trees and five times that of O trees. These patterns resulted from a nearly sixfold difference in leaf specific conductance (KL) between the youngest and oldest trees. At the time of maximum transpiration in the Y stand in May-June, gross carbon uptake (gross ecosystem production, GEP) was similar for Y and O stands despite an almost twofold difference in stand leaf area index (LAIS). However, the higher rate of water use by Y trees was not sustainable in the drought-prone environment, and between spring and late summer, KL of Y trees declined fivefold compared with a nearly twofold decline for M trees and a < 30% reduction in O trees. Because the Y stand contained a significant shrub understory and more exposed soil, there was no appreciable difference in mean daily latent energy fluxes between the Y stand and the older stands as measured by the eddy-covariance technique. These patterns resulted in 60 to 85% higher seasonal GEP and 55 to 65% higher water-use efficiency at the M and O stands compared with the Y stand. 相似文献
73.
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75.
EFFECTS OF FLUID AND COMPUTED TOMOGRAPHIC TECHNICAL FACTORS ON CONSPICUITY OF CANINE AND FELINE NASAL TURBINATES
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Raimonda Uosyte Darren J. Shaw Danielle A. Gunn‐Moore Eduardo Fraga‐Manteiga Tobias Schwarz 《Veterinary radiology & ultrasound》2015,56(5):494-502
Turbinate destruction is an important diagnostic criterion in canine and feline nasal computed tomography (CT). However decreased turbinate visibility may also be caused by technical CT settings and nasal fluid. The purpose of this experimental, crossover study was to determine whether fluid reduces conspicuity of canine and feline nasal turbinates in CT and if so, whether CT settings can maximize conspicuity. Three canine and three feline cadaver heads were used. Nasal slabs were CT‐scanned before and after submerging them in a water bath; using sequential, helical, and ultrahigh resolution modes; with images in low, medium, and high frequency image reconstruction kernels; and with application of additional posterior fossa optimization and high contrast enhancing filters. Visible turbinate length was measured by a single observer using manual tracing. Nasal density heterogeneity was measured using the standard deviation (SD) of mean nasal density from a region of interest in each nasal cavity. Linear mixed‐effect models using the R package ‘nlme’, multivariable models and standard post hoc Tukey pair‐wise comparisons were performed to investigate the effect of several variables (nasal content, scanning mode, image reconstruction kernel, application of post reconstruction filters) on measured visible total turbinate length and SD of mean nasal density. All canine and feline water‐filled nasal slabs showed significantly decreased visibility of nasal turbinates (P < 0.001). High frequency kernels provided the best turbinate visibility and highest SD of aerated nasal slabs, whereas medium frequency kernels were optimal for water‐filled nasal slabs. Scanning mode and filter application had no effect on turbinate visibility. 相似文献
76.
Andreas Palzer Kristina Haedke Karl Heinritzi Susanne Zoels Andrea Ladinig Mathias Ritzmann 《The Canadian veterinary journal. La revue veterinaire canadienne》2015,56(3):285-287
The objective of this study was to determine the associations among Haemophilus parasuis, Mycoplasma hyorhinis, and porcine reproductive and respiratory syndrome (PRRS) virus (EU-field strain) infections in 95 pigs with polyserositis. A significant association between H. parasuis and M. hyorhinis was identified. H. parasuis and M. hyorhinis were significantly more often detected in PRRS virus positive pigs. 相似文献
77.
Efficacy of Postoperative Antimicrobial Use for Clean Orthopedic Implant Surgery in Dogs: A Prospective Randomized Study in 100 Consecutive Cases
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78.
Canine cutaneous melanocytic tumours: significance of β‐catenin and survivin immunohistochemical expression
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79.
The use of a nerve stimulation test to confirm sacrococcygeal epidural needle placement in cats
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Pablo E Otero Natali Verdier Andrea S Zaccagnini Santiago E Fuensalida Lisa Tarragona Diego A Portela 《Veterinary anaesthesia and analgesia》2015,42(1):115-118
ObjectiveTo determine if a nerve stimulation test (NST) could act as a monitoring technique to confirm sacrococcygeal epidural needle placement in cats.Study designProspective experimental trial in a clinical setting.AnimalsTwenty-four adult cats, scheduled for a therapeutic procedure where epidural anesthesia was indicated.MethodsUnder general anesthesia, an insulated needle was inserted through the S3-Cd1 intervertebral space guided by the application of a fixed electrical current (0.7 mA) until a motor response was obtained. The NST was considered positive when the epidural nerve stimulation produced a motor response of the muscles of the tail, whereas it was considered negative when no motor response was evoked. In the NST positive cases, 0.3 mL kg−1 of 0.5% bupivacaine was administrated before needle withdrawal. Ten minutes after injection, epidural blockade was confirmed by the loss of perineal (anal), and pelvic limbs reflexes (patellar and withdrawal).ResultsThe use of a fixed electrical stimulation current of 0.7 mA resulted in correct prediction of sacrococcygeal epidural injection, corroborated by post bupivacaine loss of perineal and pelvic limb reflexes, in 95.8% of the cases.Conclusion and clinical relevanceThis study demonstrates the feasibility of using, in a clinical setting, an electrical stimulation test as an objective and in real-time method to confirm sacrococcygeal epidural needle placement in cats. 相似文献
80.
Comparison of the effects of propofol or alfaxalone for anaesthesia induction and maintenance on respiration in cats
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Ivo Campagna Andrea Schwarz Stefanie Keller Regula Bettschart‐Wolfensberger Martina Mosing 《Veterinary anaesthesia and analgesia》2015,42(5):484-492
ObjectiveTo compare the effects of propofol and alfaxalone on respiration in cats.Study designRandomized, ‘blinded’, prospective clinical trial.AnimalsTwenty cats undergoing ovariohysterectomy.MethodsAfter premedication with medetomidine 0.01 mg kg−1 intramuscularly and meloxicam 0.3 mg kg−1 subcutaneously, the cats were assigned randomly into two groups: group A (n = 10) were administered alfaxalone 5 mg kg−1 minute−1 followed by 10 mg kg−1 hour−1 intravenously (IV) and group P (n = 10) were administered propofol 6 mg kg−1 minute−1 followed by 12 mg kg−1hour−1 IV for induction and maintenance of anaesthesia, respectively. After endotracheal intubation, the tube was connected to a non-rebreathing system delivering 100% oxygen. The anaesthetic maintenance drug rate was adjusted (± 0.5 mg kg−1 hour−1) every 5 minutes according to a scoring sheet based on physiologic variables and clinical signs. If apnoea > 30 seconds, end-tidal carbon dioxide (Pe′CO2) > 7.3 kPa (55 mmHg) or arterial haemoglobin oxygen saturation (SpO2) < 90% occurred, manual ventilation was provided. Methadone was administered postoperatively. Data were analyzed using independent-samples t-tests, Fisher's exact test, linear mixed-effects models and binomial test.ResultsManual ventilation was required in two and eight of the cats in group A and P, respectively (p = 0.02). Two cats in both groups showed apnoea. Pe′CO2 > 7.3 kPa was recorded in zero versus four and SpO2 < 90% in zero versus six cats in groups A and P respectively. Induction and maintenance dose rates (mean ± SD) were 11.6 ± 0.3 mg kg−1 and 10.7 ± 0.8 mg kg−1 hour−1 for alfaxalone and 11.7 ± 2.7 mg kg−1 and 12.4 ± 0.5 mg kg−1 hour−1 for propofol.Conclusion and clinical relevanceAlfaxalone had less adverse influence on respiration than propofol in cats premedicated with medetomidine. Alfaxalone might be better than propofol for induction and maintenance of anaesthesia when artificial ventilation cannot be provided. 相似文献