Whole-genome QTL analysis of Stagonospora nodorum blotch resistance and validation of the SnTox4-Snn4 interaction in hexaploid wheat

Necrotrophic effectors (also known as host-selective toxins) are important determinants of disease in the wheat-Stagonospora nodorum pathosystem. To date, five necrotrophic effector-host gene interactions have been identified in this system. Most of these interactions have additive effects while some are epistatic. The Snn4-SnTox4 interaction was originally identified in a recombinant-inbred population derived from a cross between the Swiss winter wheat cultivars 'Arina' and 'Forno' using the S. nodorum isolate Sn99CH 1A7a. Here, we used a recombinant-inbred population consisting of 121 lines developed from a cross between the hexaploid land race Salamouni and the hexaploid wheat 'Katepwa' (SK population). The SK population was used for the construction of linkage maps and quantitative trait loci (QTL) detection using the Swiss S. nodorum isolate Sn99CH 1A7a. The linkage maps developed in the SK population spanned 3,228 centimorgans (cM) and consisted of 441 simple-sequence repeats, 9 restriction fragment length polymorphisms, 29 expressed sequence tag sequence-tagged site markers, and 5 phenotypic markers. The average marker density was 6.7 cM/marker. Two QTL, designated QSnb.fcu-1A and QSnb.fcu-7A on chromosome arms 1AS and 7AS, respectively, were associated with disease caused by the S. nodorum isolate Sn99CH 1A7a. The effects of QSnb.fcu-1A were determined by the Snn4-SnTox4 interaction and accounted for 23.5% of the phenotypic variation in this population, whereas QSnb.fcu-7A accounted for 16.4% of the phenotypic variation for disease but was not associated with any known effector sensitivity locus. The effects of both QTL were largely additive and collectively accounted for 35.7% of the total phenotypic variation. The results of this research validate the effects of a compatible Snn4-SnTox4 interaction in a different genetic background, and it provides knowledge regarding genomic regions and molecular markers that can be used to improve Stagonospora nodorum blotch resistance in wheat germplasm.     

Evaluation of a collagen patch as a method of enhancing ventriculotomy healing in Japanese quail (Coturnix coturnix japonica)

OBJECTIVE: To assess the ability of a porcine submucosal collagen patch to enhance ventriculotomy healing in quail. STUDY DESIGN: Histologic assessment of wound repair after ventriculotomy. Animal Population-Eighteen adult Japanese quail. METHODS: All quail had a ventriculotomy through the caudoventral thin muscle. The quail were randomly assigned to 1 of 2 groups: group I (n = 9) had routine closure and group II (n = 9) had routine closure and the application of a porcine submucosal collagen patch over the serosal surface of the ventricular suture line. Three quail from each group underwent necropsy at 7, 14, and 21 days after surgery and healing of the ventriculotomy site was evaluated by microscopy. RESULTS: Ventricular mucosal epithelium was completely healed at 21 days postoperatively. Time to restoration of the ventricular submucosal integrity was variable in both groups. There was evidence of a gross or microscopic perforation in 4 quail in group II, which was statistically significant (P =.041). Quail with perforations had significantly elevated numbers of ventricular serosal lymphoid aggregates compared with those without perforations (P =.029). There were no other significant temporal differences between group I and group II for mortality or histopathologic grading of wound healing. CONCLUSIONS: A porcine collagen patch did not enhance ventriculotomy wound healing. Subjectively, the collagen patch might have contributed to perforation by the generation of a lymphocytic xenograft rejection response. CLINICAL RELEVANCE: Ventriculotomy can be safely performed using routine closure methods in healthy birds.     

Effects of transcorneal iridal photocoagulation on the canine corneal endothelium using a diode laser

Objective To investigate the potential damage to the canine corneal endothelium following transcorneal iridal laser photocoagulation using a semiconductor diode laser. Animals studied Sixteen young mongrel dogs. Procedures Baseline corneal endothelial cell counts and corneal thickness were measured in the central and temporal quadrants using a noncontact specular microscope under general anesthesia. Transcorneal iridal photocoagulation was applied using a semiconductor diode laser in a continuous mode with the use of an operating microscope. Fifteen dogs were treated, and the sixteenth dog served as a control. Fifteen different treatment combinations were randomly assigned to the 30 eyes; the fellow eye was treated differently. Three treatment factors were investigated: (1) laser energy intensity, (2) target tissue to endothelial distance, and (3) laser application duration. After 3 weeks the dogs were euthanized, specular microscopy was repeated, and the cornea was examined by scanning electron microscopy. Results Dyscoria and focal iris darkening were noted in all eyes immediately following laser treatment. Focal corneal edema (n = 2) and an incipient anterior capsular cataract (n = 1) were also noted. Baseline mean corneal endothelial cell densities were 2530 cells/mm² centrally and 2607 cells/mm² temporally. Postlaser corneal endothelial cell densities were 2499 cells/mm² centrally and 2523 cells/mm² temporally. Mean prelaser corneal thickness measurements were 0.555 mm centrally and 0.549 mm temporally. Postlaser corneal thickness measurements were 0.580 mm centrally and 0.554 mm temporally. Statistical analyzes revealed no significant changes in endothelial cell densities (P > 0.05) or corneal thickness (P > 0.05) induced by any treatment combination. Aside from tissue handling and processing artifacts, scanning electron microscopy revealed no endothelial cell damage. Conclusions Our study demonstrated by specular and scanning electron microscopy that diode laser iridal photocoagulation had no significant effect on the canine corneal endothelium within the parameters described. However, one must take into consideration the young age of the dogs and the potential for corneal endothelial cell regeneration in young dogs, and the relatively short period of postoperative study.     

Contents of Volume 11

Volume Contents

Contents of Volume 11     

Evaluation of cross-reactivity of allergens by use of intradermal testing in atopic dogs

OBJECTIVE: To examine cross-reactivity of aeroallergens in Colorado and surrounding states by evaluating concurrent positive reactions of related and nonrelated allergens of intradermal tests in dogs. SAMPLE POPULATION: Intradermal test results of 268 atopic dogs. PROCEDURE: A retrospective evaluation of skin test results for 268 dogs was performed. Pairs of closely related and nonrelated allergens were evaluated. Group 1 consisted of closely related allergens with demonstrated antibody cross-reactivity in humans. In group 2, allergens of the same plant group (ie, trees, grasses, or weeds) that were not closely related were paired. In group 3, allergen pairs were of different plant groups. Plant allergens were paired with dust mite allergens, animal dander, or mold spores in group 4. In the last group, allergens not derived from plants were paired. Data were evaluated twice by use of a different definition of a positive reaction. Significance of the difference between group means of log odds ratios was estimated by use of a boot-strap percentile confidence interval. RESULTS: Significant differences in the number of concurrent positive reactions were not found between related versus nonrelated grass, weed, or tree allergens. Significant differences in the number of concurrent positive reactions were found between plant allergens of different groups (ie, grasses, weeds, and trees) and plant allergens of the same groups, related or nonrelated, as well as between plant-derived and nonplant-derived allergens. Many dogs reacting to a specific allergen did not react to a closely related allergen at the same time. CONCLUSION: These results provide evidence against clinically relevant cross-reactivity and suggest that allergen-specific immunotherapy should be formulated on the basis of single allergen test results.     

Cardiopulmonary effects of xylazine and acepromazine in pregnant cows in late gestation

OBJECTIVE: To determine effects of sedation achieved by xylazine (XYL) or acepromazine (ACE) on cardiopulmonary function and uterine blood flow in cows in late gestation. ANIMALS: 8 cows between 219 and 241 days of gestation. PROCEDURE: Doses of ACE (0.02 mg/kg) or XYL (0.04 mg/kg) were administered IV. Measurements were obtained to determine cardiopulmonary effects and oxygen delivery to the uterus. RESULTS: Heart rate was not significantly affected by administration of ACE, but it decreased markedly after administration of XYL. Uterine artery flow was decreased at all times by XYL and was always less than for ACE. Xylazine increased uterine vascular resistance through 30 minutes and caused reduced PaO2 and increased PaCO2 at all time periods. Acepromazine caused a 5% decrease in PaO2 only at 5 minutes. Xylazine reduced oxygen delivery by 59% at 5 minutes and 32% at 45 minutes. In contrast, ACE caused a nonsignificant reduction of oxygen delivery by 16% at 15 minutes and a return to baseline values by 45 minutes CONCLUSIONS AND CLINICAL RELEVANCE: Xylazine markedly reduces flow and availability of oxygenated blood to the uterus, which may critically impair delivery of oxygen to the fetus at a stressful and important time of development or delivery. Acepromazine was associated with slight reductions of much shorter duration. When XYL is used to sedate pregnant cows, it could impose physiologic distress on the fetus and potentially increase fetal morbidity and mortality. When sedation of the dam is desirable, ACE could be an alternative to XYL.     

Clinical signs and treatment of chronic uterine torsion in two mares

Two mares were evaluated because of chronic uterine torsions of 2 and 4 weeks' duration; both were pyrectic, anemic, tachycardic, and anorectic, had signs of depression, and had an abnormal uterus and contents on transrectal examination. Both mares underwent cesarean section for lysis of adhesions from the uterus to the peritoneum, correction of the torsion, and ovariohysterectomy Both mares recovered with only minor complications and returned to be used as riding horses. Chronic uterine torsion should be considered in mares in late stages of gestation that have vague clinical signs and transrectal palpation findings that are unlike those described in typical cases of uterine torsion. Prognosis for life can be good after treatment by ventral midline celiotomy, cesarean section, correction of the torsion, and ovariohysterectomy.     

Infusion of guaifenesin,ketamine, and medetomidine in combination with inhalation of sevoflurane versus inhalation of sevoflurane alone for anesthesia of horses

OBJECTIVE: To evaluate effects of infusion of guaifenesin, ketamine, and medetomidine in combination with inhalation of sevoflurane versus inhalation of sevoflurane alone for anesthesia of horses. DESIGN: Randomized clinical trial. ANIMALS: 40 horses. PROCEDURE: Horses were premedicated with xylazine and anesthetized with diazepam and ketamine. Anesthesia was maintained by infusion of guaifenesin, ketamine, and medetomidine and inhalation of sevoflurane (20 horses) or by inhalation of sevoflurane (20 horses). A surgical plane of anesthesia was maintained by controlling the inhaled concentration of sevoflurane. Sodium pentothal was administered as necessary to prevent movement in response to surgical stimulation. Hypotension was treated with dobutamine; hypoxemia and hypercarbia were treated with intermittent positive-pressure ventilation. The quality of anesthetic induction, maintenance, and recovery and the quality of the transition to inhalation anesthesia were scored. RESULTS: The delivered concentration of sevoflurane (ie, the vaporizer dial setting) was significantly lower and the quality of transition to inhalation anesthesia and of anesthetic maintenance were significantly better in horses that received the guaifenesin-ketamine-medetomidine infusion than in horses that did not. Five horses, all of which received sevoflurane alone, required administration of pentothal. Recovery time and quality of recovery were not significantly different between groups, but horses that received the guaifenesin-ketamine-medetomidine infusion required fewer attempts to stand. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in horses, the combination of a guaifenesin-ketamine-medetomidine infusion and inhalation of sevoflurane resulted in better transition and maintenance phases while improving cardiovascular function and reducing the number of attempts needed to stand after the completion of anesthesia, compared with inhalation of sevoflurane.