A comparison of corneal sensitivity between healthy cats and cats with corneal sequestra

In order to establish reference values for corneal sensitivity in ophthalmologically healthy persians (n = 40) and domestic short hair cats (n = 60) a prospective study was conducted. Furthermore corneal sensitivity in 48 cats with a corneal sequestrum was measured. Corneal sensitivity was recorded with the help of the aesthesiometer according to Cochet and Bonnet in five different corneal locations (central, nasal, dorsal, temporal, and ventral). The sensitivity for the central corneal region was recorded as amounting to 3.58 +/- 0.56 cm in ophthalmologically healthy domestic short hair cats and to 2.97 +/- 0.58 cm in healthy persian cats. The sensitivity of the central corneal area of a cat with a corneal sequester only amounts to 2.03 +/- 0.53 cm. Between the diseased and the healthy eyes no statistical difference could be demonstrated for any of the measured corneal locations. The sensitivity of the peripheral corneal locations is significantly lower than that of the central corneal region in all three groups examined.     

Mechano-sorptive creep in wood fibres

In order to investigate the way in which fibre properties affect the mechano-sorptive creep phenomenon in paper, single wood fibres were exposed to tensile stresses at a constant humidity of 80% relative humidity (RH) and in a cyclic humidity environment varying between 80 and 30% RH. Contrary to earlier claims, it was demonstrated that single wood fibres exposed to a cyclic RH show a considerably higher creep than that corresponding to the highest RH experienced in the cycle, i.e., a mechano-sorptive behaviour. The creep strain rate at cyclic humidity was shown to be a function of the creep rate at constant climate, and to be an apparent linear function of the applied stress.     

Regeneration patterns in boreal Scots pine glades linked to cold-induced photoinhibition

Regeneration patterns of Pinus sylvestris L. juveniles in central Siberian glades were studied in relation to cold-induced photoinhibition. Spatial distribution of seedlings in different height classes revealed higher seedling densities beneath the canopy than beyond the canopy, and significantly higher densities of seedlings < 50 cm tall on the north side of the trees. These patterns coincided with differences in light conditions. Compared with plants on the north side of canopy trees (north-exposed), photosynthetic photon flux (PPF) received by plants on the south side of canopy trees (south-exposed) was always higher, making south-exposed plants more susceptible to photoinhibition, especially on cool mornings. Chlorophyll fluorescence data revealed lower photochemical efficiency and increased non-photochemical quenching of small (20-50 cm in height), south-exposed seedlings from spring to early autumn, indicating increased excitation pressure on photosynthesis. Maximum rate of oxygen evolution was less in south-exposed plants than in north-exposed plants. Increased pools of xanthophyll cycle pigments and formation of the photoprotective zeaxanthin provided further evidence for the higher susceptibility to photoinhibition of south-exposed seedlings. A linear mixed model analysis explained many of the physiological differences observed in seedlings according to height class and aspect with early morning temperature and PPF as predictors. The link between photoinhibition and differential distribution of seedlings by height class suggests that photoinhibition, together with other environmental stresses, decreases the survival of small, south-exposed P. sylvestris seedlings, thereby significantly affecting the regeneration pattern of central Siberian pine glades.     

Application of the glutaraldehyde test in cattle

In a cohort study involving 62 cows from an experimental farm, the kinetics of the glutaraldehyde test (GAT) according to Sandholm (1974) was examined by testing samples of EDTA blood, lithium heparinate blood, serum, and plasma taken at various intervals. Total protein was measured in serum, and fibrinogen was determined in plasma. Gamma globulin was measured by electrophoresis. All glutaraldehyde tests were performed in duplicates, and the relation of the two results was used as measurement of precision. Optimal cut-off of the GAT time was determined as the zenith of the sum of sensitivity and specificity of various intervals for detecting combinations of gamma globulin and fibrinogen levels above 32 g/l. Precision was the best in EDTA blood. The relation between coagulation time and gamma globulin plus fibrinogen is best described by an exponential curve. The maximum value for the sum of sensitivity and specificity was found at 7 and 8 min. Seven days was the shortest interval observed between a negative test result (>15 min) and a strongly positive test result (<3 min). Twenty-one days was the shortest interval observed between a strongly positive test result and a negative test result. EDTA blood should be used for the GAT. A cut-off of 8 min yields the highest efficiency. Test results must be viewed in light of clinical findings.     

Comparison of analgesic efficacy of preoperative or postoperative carprofen with or without preincisional mepivacaine epidural anesthesia in canine pelvic or femoral fracture repair

Objective— To compare analgesic efficacy of preoperative versus postoperative administration of carprofen and to determine, if preincisional mepivacaine epidural anesthesia improves postoperative analgesia in dogs treated with carprofen. Study Design— Blind, randomized clinical study. Animals— Dogs with femoral (n=18) or pelvic (27) fractures. Methods— Dogs were grouped by restricted randomization into 4 groups: group 1=carprofen (4 mg/kg subcutaneously) immediately before induction of anesthesia, no epidural anesthesia; group 2=carprofen immediately after extubation, no epidural anesthesia; group 3=carprofen immediately before induction, mepivacaine epidural block 15 minutes before surgical incision; and group 4=mepivacaine epidural block 15 minutes before surgical incision, carprofen after extubation. All dogs were administered carprofen (4 mg/kg, subcutaneously, once daily) for 4 days after surgery. Physiologic variables, nociceptive threshold, lameness score, pain, and sedation (numerical rating scale [NRS], visual analog scale [VAS]), plasma glucose and cortisol concentration, renal function, and hemostatic variables were measured preoperatively and at various times after surgery. Dogs with VAS pain scores >30 were administered rescue analgesia. Results— Group 3 and 4 dogs had significantly lower pain scores and amount of rescue analgesia compared with groups 1 and 2. VAS and NRS pain scores were not significantly different among groups 1 and 2 or among groups 3 and 4. There was no treatment effect on renal function and hemostatic variables. Conclusions— Preoperative carprofen combined with mepivacaine epidural anesthesia had superior postoperative analgesia compared with preoperative carprofen alone. When preoperative epidural anesthesia was performed, preoperative administration of carprofen did not improve postoperative analgesia compared with postoperative administration of carprofen. Clinical Relevance— Preoperative administration of systemic opioid agonists in combination with regional anesthesia and postoperative administration of carprofen provides safe and effective pain relieve in canine fracture repair.     

In vitro comparison of tibial plateau leveling osteotomy with and without use of a tibial plateau leveling jig

OBJECTIVE: To evaluate the influence of a tibial plateau leveling jig on osteotomy orientation, fragment reduction, and postoperative tibial plateau angle (TPA) during tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: In vitro experimental study. ANIMALS: Large-breed canine cadavers (n=20). METHODS: TPLO was performed on 40 hindlimbs using 4 methods. Group 1: Jig; dogs in dorsal recumbency with the osteotomy parallel to the distal jig pin. Groups 2-4: No jig; dogs in lateral recumbency with the osteotomy in a vertical orientation (group 2: tibia parallel to the table top; group 3: controlled superimposition of the femoral condyles; group 4: internal rotation of the tibia). Postoperative TPA, fragment reduction, and osteotomy orientation relative to the tibial plateau were compared. Positive or negative values denoted deviation from parallel relative to the tibial plateau. RESULTS: Postoperative TPA, fragment reduction, and proximodistal osteotomy orientation were not significantly different between groups. Craniocaudal osteotomy orientation was significantly different (P<.005) from the tibial plateau. Median deviations were -4.0 degrees (group 1), 11.8 degrees (group 2), 11.2 degrees (group 3), and 0.2 degrees (group 4). Group 1 was not significantly different from group 4. CONCLUSIONS: A jig is not essential for osteotomy orientation, tibial plateau rotation, or fragment reduction. Comparable results were achieved performing a vertical osteotomy with the tibia slightly internally rotated (10 degrees -15 degrees) and parallel to the table surface. CLINICAL RELEVANCE: TPLO without use of a jig reduces surgical trauma, is less time consuming, and reduces cost.     

Seasonal acclimation of photosystem II in Pinus sylvestris. II. Using the rate constants of sustained thermal energy dissipation and photochemistry to study the effect of the light environment

Photosynthesis in evergreen conifers is characterized by down-regulation in autumn and rapid up-regulation in spring. This seasonal pattern is largely driven by temperature, but the light environment also plays a role. In overwintering Scots pine (Pinus sylvestris L.) trees, PSII is less down-regulated and recovers faster from winter stress in shaded needles than in needles exposed to full sunlight. Because the effect of light on the seasonal acclimation of PSII has not been quantitatively studied under field conditions, we used the rate constants for sustained thermal energy dissipation and photochemistry to investigate the dynamics and kinetics of the seasonal acclimation of PSII in needles exposed to different light environments. We monitored chlorophyll fluorescence and needle pigment concentration during the winter and spring in Scots pine seedlings growing in the field in different shading treatments, and within the crowns of mature trees. The results indicated that differences in acclimation of PSII in overwintering Scots pine among needles exposed to different light environments can be chiefly attributed to sustained thermal dissipation. We also present field evidence that zeaxanthin-facilitated thermal dissipation and aggregation of thylakoid membrane proteins are key mechanisms in the regulation of sustained thermal dissipation in Scots pine trees in the field.     

Monitoring potato seed lots to control blackleg in fields in Switzerland and southern Germany

Potato blackleg is a seedborne disease that can cause significant economic losses for growers. Disease development depends mainly on two drivers, namely seed inoculum and local climatic conditions. To better establish the relationship between these two drivers, blackleg development was monitored in Swiss field trials at multiple locations from 2010 to 2013 involving three sets of naturally infected seed lots planted in each of three locations. The seed lot itself was thereby the most important factor explaining differences in disease development, rather than environmental factors. In a further on-farm project conducted at various locations in Switzerland and southern Germany from 2013 to 2015, the implementation of a seed-testing procedure was investigated. A total of 177 seed lots were tested for natural latent infection with soft rot Pectobacteriaceae and the corresponding blackleg incidence was tracked in 242 fields. The reliability of the relationship between latent infection and field incidence was found to be strongly linked to the bacterial species. Dickeya spp. field infection could be predicted with an acceptable reliability, whereas Pectobacterium carotovorum subsp. brasiliense, even when detected as latent tuber infection, was not consistently expressed as visual blackleg. Moreover, commonly found mixed latent infections with several bacterial species made it even harder to predict which bacteria would cause blackleg symptoms. Finally, variability in the reliability of seed testing may also be explained by differences in local farming practices. These trials over several years with naturally infected potato seed highlight the usefulness and limits of seed testing to manage blackleg.     

Micromechanical properties of common yew (Taxus baccata) and Norway spruce (Picea abies) transition wood fibers subjected to longitudinal tension

The longitudinal modulus of elasticity of common yew is astonishingly low in light of its high raw density. At least this was found for specimens examined at the solid wood level and at the tissue level. However, to reveal if this low axial stiffness is also present at the cellular level, tensile tests were performed on individual yew fibers and on spruce fibers for reference. The results revealed a low stiffness and a high strain to fracture for yew when compared with spruce. This compliant behavior was ascribed to a relatively high microfibril angle of yew measured by X-ray scattering. It can be concluded that the high compliance of yew observed at higher hierarchical levels is obviously controlled by a structural feature present at the cell wall level. In future studies, the biomechanical function of this compliant behavior for the living yew tree would be of particular interest.     

Excitation energy partitioning and quenching during cold acclimation in Scots pine

We studied the influence of two irradiances on cold acclimation and recovery of photosynthesis in Scots pine (Pinus sylvestris L.) seedlings to assess mechanisms for quenching the excess energy captured by the photosynthetic apparatus. A shift in temperature from 20 to 5 degrees C caused a greater decrease in photosynthetic activity, measured by chlorophyll fluorescence and oxygen evolution, in plants exposed to moderate light (350 micromol m(-2) s(-1)) than in shaded plants (50 micromol m(-2) s(-1)). In response to the temperature shift, maximal photochemical efficiency of photosystem II (PSII), measured as the ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) of dark-adapted samples, decreased to 70% in exposed seedlings, whereas shaded seedlings maintained Fv/Fm close to initial values. After a further temperature decrease to -5 degrees C, only 8% of initial Fv/Fm remained in exposed plants, whereas shaded plants retained 40% of initial Fv/Fm. Seven days after transfer from -5 to 20 degrees C, recovery of photochemical efficiency was more complete in the shaded plants than in the exposed plants (87 and 65% of the initial Fv/Fm value, respectively). In response to cold stress, the estimated functional absorption cross section per remaining PSII reaction center increased at both irradiances, but the increase was more pronounced in exposed seedlings. Estimates of energy partitioning in the needles showed a much higher dissipative component in the exposed seedlings at low temperatures, pointing to stronger development of non-photochemical quenching at moderate irradiances. The de-epoxidation state of the xanthophyll cycle pigments increased in exposed seedlings at 5 degrees C, contributing to the quenching capacity, whereas significant de-epoxidation in the shaded plants was observed only when temperatures decreased to -5 degrees C. Thermoluminescence (TL) measurements of PSII revealed that charge recombinations between the second oxidation state of Mn-cluster S2 and the semireduced secondary electron acceptor quinone Q(B)- (S2Q(B)-) were shifted to lower temperatures in cold-acclimated seedlings compared with control seedlings and this effect depended on irradiance. Concomitant with this, cold-acclimated seedlings demonstrated a significant shift in the S2 recombination with primary acceptor Q(A)- (S2Q(A)-) characteristic TL emission peak to higher temperatures, thus narrowing the redox potential gap between S2Q(B)- and S2Q(A)-, which might result in increased probability for non-radiative radical pair recombination between the PSII reaction center chlorophyll a (P680+) and Q(A)- (P680+)Q(A)-) (reaction center quenching) in cold-acclimated seedlings. In Scots pine seedlings, mechanisms of quenching excess light energy in winter therefore involve light-dependent regulation of reaction center content and both reaction center-based and antenna-based quenching of excess light energy, enabling them to withstand high excitation pressure under northern winter conditions.