A new equine peripheral caries grading system: Are the caries likely active or inactive?     

Kirsten Jackson  Erin Kelty  Marc Tennant 《Equine veterinary journal》2021,53(4):780-786

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Medicine and veterinary medicine. Extraordinarily many comparisons but still different     

Peeters K 《Tijdschrift voor diergeneeskunde》2007,132(16):630-631

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Changes in forest soil organic matter pools after a decade of elevated CO₂ and O₃     

Kirsten S. Hofmockel  Donald R. Zak  Kelly K. Moran 《Soil biology & biochemistry》2011,43(7):1518-1527

The impact of rising atmospheric carbon dioxide (CO₂) may be mitigated, in part, by enhanced rates of net primary production and greater C storage in plant biomass and soil organic matter (SOM). However, C sequestration in forest soils may be offset by other environmental changes such as increasing tropospheric ozone (O₃) or vary based on species-specific growth responses to elevated CO₂. To understand how projected increases in atmospheric CO₂ and O₃ alter SOM formation, we used physical fractionation to characterize soil C and N at the Rhinelander Free Air CO₂-O₃ Enrichment (FACE) experiment. Tracer amounts of ¹⁵NH₄⁺ were applied to the forest floor of Populus tremuloides, P. tremuloides-Betula papyrifera and P. tremuloides-Acer saccharum communities exposed to factorial CO₂ and O₃ treatments. The ¹⁵N tracer and strongly depleted ¹³C-CO₂ were traced into SOM fractions over four years. Over time, C and N increased in coarse particulate organic matter (cPOM) and decreased in mineral-associated organic matter (MAOM) under elevated CO₂ relative to ambient CO₂. As main effects, neither CO₂ nor O₃ significantly altered ¹⁵N recovery in SOM. Elevated CO₂ significantly increased new C in all SOM fractions, and significantly decreased old C in fine POM (fPOM) and MAOM over the duration of our study. Overall, our observations indicate that elevated CO₂ has altered SOM cycling at this site to favor C and N accumulation in less stable pools, with more rapid turnover. Elevated O₃ had the opposite effect, significantly reducing cPOM N by 15% and significantly increasing the C:N ratio by 7%. Our results demonstrate that CO₂ can enhance SOM turnover, potentially limiting long-term C sequestration in terrestrial ecosystems; plant community composition is an important determinant of the magnitude of this response.  相似文献   

不同含水量天然硫酸盐盐渍土中二氧化碳和氧化亚氮的排放     

Resham THAPA  Amitava CHATTERJEE  Abbey WICK  Kirsten BUTCHER 《土壤圈》2017,27(5):868-876

Soil salinization may negatively affect microbial processes related to carbon dioxide(CO_2) and nitrous oxide(N_2O) emissions. A short-term laboratory incubation experiment was conducted to investigate the effects of soil electrical conductivity(EC) and moisture content on CO_2 and N_2O emissions from sulfate-based natural saline soils. Three separate 100-m long transects were established along the salinity gradient on a salt-affected agricultural field at Mooreton, North Dakota, USA. Surface soils were collected from four equally spaced sampling positions within each transect, at the depths of 0–15 and 15–30 cm. In the laboratory, artificial soil cores were formed combining soils from both the depths in each transect, and incubated at 60% and 90% water-filled pore space(WFPS) at 25?C. The measured depth-weighted EC of the saturated paste extract(EC_e) across the sampling positions ranged from 0.43 to 4.65 dS m~(-1). Potential nitrogen(N) mineralization rate and CO_2 emissions decreased with increasing soil EC_e, but the relative decline in soil CO_2 emissions with increasing ECe was smaller at 60% WFPS than at 90% WFPS. At 60% WFPS, soil N_2O emissions decreased from 133 μg N_2O-N kg~(-1) soil at EC_e 0.50 dS m~(-1) to 72 μg N_2O-N kg~(-1) soil at EC_e = 4.65 dS m~(-1). In contrast, at 90% WFPS,soil N_2O emissions increased from 262 μg N_2O-N kg~(-1) soil at EC_e = 0.81 dS m~(-1) to 849 μg N_2O-N kg~(-1) soil at EC_e = 4.65 dS m~(-1), suggesting that N_2O emissions were linked to both soil ECe and moisture content. Therefore, spatial variability in soil EC_e and pattern of rainfall over the season need to be considered when up-scaling N_2O and CO_2 emissions from field to landscape scales.  相似文献   

MAGNETIC RESONANCE IMAGING FINDINGS IN THE EQUINE DEEP DIGITAL FLEXOR TENDON AND DISTAL SESAMOID BONE IN ADVANCED NAVICULAR DISEASE—AN EX VIVO STUDY     

Valeria Busoni  Marianne Heimann  Jacques Trenteseaux  Frédéric Snaps  Robert F. Dondelinger 《Veterinary radiology & ultrasound》2005,46(4):279-286

We describe the abnormal magnetic resonance (MR) imaging findings in the deep digital flexor tendon (DDFT) and distal sesamoid bone in horses with radiographic changes compatible with navicular syndrome. Thirteen postmortem specimens were examined using a 1.5-T magnetic field, with spin echo (SE) T1-weighted, turbo SE (TSE) proton density-weighted (with and without fat saturation), and fat saturation TSE T2-weighted sequences. The limbs were then dissected to compare the MR findings with the gross assessment and histologic examination of the DDFT and distal sesamoid bones. Tendonous abnormalities were detected by MR imaging in 12 DDFTs and confirmed at necropsy. Most tendon lesions were located at the level of the distal sesamoid bone and the proximal recess of the podotrochlear bursa. Tendon lesions were classified based on their MR imaging features as core lesions, dorsal lesions, dorsal abrasions, and parasagittal splits. Areas of increased MR signal in the DDFTs were characterized by tendon fiber disturbance and lack of continuity of the collagen fibers, foci of edema, hemorrhages, and formation of lakes containing eosinophilic plasma-like material or amphophilic material of low density. Bone marrow signal alterations in the distal sesamoid bone were seen in all digits. Two main phenomena were responsible for the abnormal signal, respectively, in T1-weighted (decreased signal) and in T2-weighted fat-suppressed images (increased signal): a decrease in the fat marrow content in the trabecular spaces and an increase in the fluid content. Histologic examination revealed foci of bone marrow edema, hemorrhage, necrosis, and fibrosis. Cyst formation and trabecular abnormalities (disorganization, thinning, remodelling) were also observed in areas of abnormal signal intensity. Increased bone density because of trabecular thickening induced a decrease in signal in all sequences.  相似文献   

The Use of a GUS Transformant of Trichoderma Harzianum, Strain T3a, to Study Metabolic Activity in the Spermosphere and Rhizosphere Related to Biocontrol of Pythium Damping-off And Root Rot     

Helge Green  Nina Heiberg  Kirsten Lejbølle  Dan Funck Jensen 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(3):349-359

The activity of Trichoderma harzianum in the spermosphere and rhizosphere of different plant species was studied by use of a beta-glucuronidase (GUS) transformant (strain T3a). Hereby, direct observation of micro-habitats supporting metabolic activity of T. harzianum is reported. Germination of conidia and mycelial growth were not supported by exudates from healthy roots of various ages. Instead, growth and activity of T. harzianum depended on access to dead organic substrates such as seed coats, decaying roots, and wounds, including those caused by infecting pathogens. A correlation between the GUS activity of T. harzianum and the biomass of Pythium ultimum in infected roots was established. On the basis of our observations, we suggest that the biocontrol ability of T. harzianum involves competition with the pathogen for substrates including the seed coat, and wounded or infected root tissue.  相似文献   

Baiting intervals and duration of control of the small fox tapeworm: a simulation study     

Hansen F  Tackmann K  Jeltsch F  Thulke HH 《Berliner und Münchener tier?rztliche Wochenschrift》2003,116(7-8):299-305

Field trials to control the small fox tapeworm Echinococcus multilocularis failed to reduce the prevalence of the parasite persistently. With the experience from this empirical work, a simulation model for the population dynamics of the small fox tapeworm was developed. This model is used to examine the effect of different control strategies. Sufficient control duration is able to eradicate the parasite in simulation experiments. Baiting intervals of 4 or 6 weeks were found to be more efficient than shorter or longer intervals. The strategy used in field trials showed no sustainable effect in any of the simulation experiments. The applicability of simulation models for the planning of control measures for wildlife diseases is discussed.  相似文献   

Resolution of chylothorax after resection of rib chondroma in a dog     

Watine S  Hamaide A  Peeters D  Saunders J  Heimann M  Day MJ  Clercx C 《The Journal of small animal practice》2003,44(12):546-549

A six-year-old, male dobermann was presented with a history of dyspnoea and bouts of coughing. Radiography and computed tomography of the thorax showed pleural effusion and a well-circumscribed, calcified mass of 10 cm in diameter, appearing to originate from the left first rib. Thoracocentesis revealed that the pleural fluid was chylous in nature. An incisional biopsy was performed, which gave a histological diagnosis of chondroma. Resolution of the chylothorax after en-bloc surgical removal of the tumour suggested that the rib tumour was the initiating cause of the chylothorax. Seventeen months later, rib neoplasia recurred without pleural effusion, and was removed successfully. To the authors' knowledge, rib chondroma, which is an unusual tumour in dogs, has not been previously documented as a cause of chylothorax.  相似文献   

Controlling Echinococcus multilocularis-ecological implications of field trials     

Hansen F  Tackmann K  Jeltsch F  Wissel C  Thulke HH 《Preventive veterinary medicine》2003,60(1):91-105

Two field trials to reduce the prevalence of Echinococcus multilocularis in foxes have been conducted in recent years. Although both trials reduced prevalence considerably, they failed to eradicate the parasite in the study region. Following the control trial in northern Germany, prevalence recovered unexpectedly and rapidly, reaching pre-control levels five quarters (15 months) after the end of control. To understand the internal dynamics of the parasite-host system's reaction to control, we developed a spatially explicit simulation model, Echi. The simulation model incorporates the information available concerning fox tapeworm population dynamics.Using epidemiological parameters to adjust pre-control prevalence, the model predicts the temporal evolution of the prevalence of E. multilocularis in controlled foxes without departing from the range of uncertainty of the field data. However, the model does not predict the rapid pre-control recovery observed in the field trial.The deviation of the model's prediction from field data indicates the involvement of processes not yet taken into account. We modified the model step by step to mimic processes with the potential to cause the rapid post-control recovery of the prevalence of E. multilocularis in foxes.Neither the longevity of tapeworm eggs nor the migratory behaviour of foxes showed any influence on the post-control reaction of the parasite-host system. However, landscape structures leading to a heterogeneous distribution of infected foxes have the potential to alter the system's reaction to control. If infected foxes are concentrated in multiple clusters in the landscape, the model prediction tallied with the range of uncertainty of the field data. Such spatial distribution of infected foxes may be caused by differential abiotic conditions influencing the survival of tapeworm eggs.The model was found to comply best with field data if the foxes acquire partial immunity by being exposed to the fox tapeworm.Both hypotheses explaining the rapid post-control recovery of the prevalence of E. multilocularis observed in the fox population were supported by field data.Both hypotheses have far-reaching consequences for future control trials. The spatial aggregation of infected foxes would enable control efforts to be concentrated on these highly infected areas. However, the acquisition of immunity acts as a buffer to control, necessitating intensified control measures.  相似文献   

Population-based study of fecal shedding of Clostridium perfringens in broodmares and foals     

Tillotson K  Traub-Dargatz JL  Dickinson CE  Ellis RP  Morley PS  Hyatt DR  Magnuson RJ  Riddle WT  Bolte D  Salman MD 《Journal of the American Veterinary Medical Association》2002,220(3):342-348

OBJECTIVE: To determine the percentage of broodmares and foals that shed Clostridium perfringens in their feces and classify the genotypes of those isolates. DESIGN: Prospective cross-sectional study. ANIMALS: 128 broodmares and their foals on 6 equine premises. PROCEDURES: Anaerobic and aerobic bacteriologic cultures were performed on feces collected 3 times from broodmares and foals. All isolates of C. perfringens were genotyped. RESULTS: Clostridium perfringens was isolated from the feces of 90% of 3-day-old foals and 64% of foals at 8 to 12 hours of age. A lower percentage of broodmares and 1- to 2-month-old foals shed C. perfringens in their feces, compared with neonatal foals. Among samples with positive results, C. perfringens type A was the most common genotype identified (85%); C. perfringens type A with the beta2 toxin gene was identified in 12% of samples, C. perfringens type A with the enterotoxin gene was identified in 2.1% of samples, and C. perfringens type C was identified in < 1% of samples. CONCLUSIONS AND CLINICAL RELEVANCE: Clostridium perfringens was identified from the feces of all but 6 foals by 3 days of age and is likely part of the normal microflora of neonatal foals. Most isolates from broodmares and foals are C. perfringens type A; thus, the clinical relevance of culture results alone is questionable. Clostridium perfringens type C, which has been associated with neonatal enterocolitis, is rarely found in the feces of horses.  相似文献