Tilmicosin-induced bovine neutrophil apoptosis is cell-specific and downregulates spontaneous LTB4 synthesis without increasing Fas expression

The pathology of bacterial pneumonia, such as seen in the bovine lung infected with Mannheimia haemolytica, is due to pathogen virulence factors and to inflammation initiated by the host. Tilmicosin is a macrolide effective in treating bacterial pneumonia and recent findings suggest that this antibiotic may provide anti-inflammatory benefits by inducing polymorphonuclear neutrophilic leukocyte (PMN) apoptosis. Using an in vitro bovine system, we examined the cell-specificity of tilmicosin, characterized the changes in spontaneous leukotriene B4 (LTB4) synthesis by PMN exposed to the macrolide, and assessed its effects on PMN Fas expression. Previous findings demonstrated that tilmicosin is able to induce PMN apoptosis. These results were confirmed in this study by the Annexin-V staining of externalized phosphatidylserine and the analysis with flow cytometry. The cell-specificity of tilmicosin was assessed by quantification of apoptosis in bovine PMN, mononuclear leukocytes, monocyte-derived macrophages, endothelial cells, epithelial cells, and fibroblasts cultured with the macrolide. The effect of tilmicosin on spontaneous LTB4 production by PMN was evaluated via an enzyme-linked immunosorbent assay. Finally, the mechanisms of tilmicosin-induced PMN apoptosis were examined by assessing the effects of tilmicosin on surface Fas expression on PMN. Tilmicosin-induced apoptosis was found to be at least partially cell-specific, as PMN were the only cell type tested to die via apoptosis in response to incubation with tilmicosin. PMN incubated with tilmicosin under conditions that induce apoptosis spontaneously produced less LTB4, but did not exhibit altered Fas expression. In conclusion, tilmicosin-induced apoptosis is specific to PMN, inhibits spontaneous LTB4 production, and occurs through a pathway independent of Fas upregulation.     

禽用谷物品质的预测和改善

小麦、大麦和黑小麦等谷物在营养价值方面(例如代谢能)的变化已被业界人士广为了解,这种营养价值的变异造成了肉鸡料肉比不可预测及在某些情况下能产生粘湿的粪便.现已充分认识到,上述谷物中所含的可溶性长链阿拉伯木聚糖和β-葡聚糖是引起肠道食糜高粘性等问题的主要原因.非淀粉多糖酶,如木聚糖酶和β-葡聚糖酶,能通过部分的破坏上述物质的纤维结构从而有效地减少肠内的粘性.这种作用的衍生效应是成倍的,而最终结果是增加了养分的利用率.自80年代末期开始,使用小麦、大麦和黑小麦作为饲料能源谷物的国家便已经商业化地使用非淀粉多糖酶来提高养殖的经济效益,而最近研发的小麦品质快速测定法(芬兰饲料国际公司的AvicheckTM 应用软件)能使饲料厂根据小麦的品质和用量来优化酶制剂的最佳添加量,从而达到最大的利润.     

Flash electroretinography in standing horses using the DTL microfiber electrode

Purpose The goal of our study was the evaluation of a practical method for the recording of flash electroretinograms (ERGs) in sedated, standing horses with the DTL? microfiber electrode. Methods The horses were sedated intravenously with detomidine hydrochloride (0.015 mg/kg). The pupil was dilated and the auriculopalpebral nerve was blocked. The ERGs were recorded with the active electrode on the cornea (DTL?), the reference electrode near the lateral canthus, and the ground electrode over the occipital bone. The light intensities of the white strobe light were 0.03 cd·s/m² (scotopic) and 3 cd·s/m² (scotopic and photopic). Photopic and scotopic single flash and flicker responses to Ganzfeld stimulation were recorded. During the 20‐min dark adaptation period the retina was stimulated every 5 min with the 0.03 cd·s/m² single flash. Results The median b‐wave amplitudes and implicit times were 38 µV and 33 ms (photopic cone‐dominated response), 43 µV and 63 ms (5‐min dark adaptation), 72 µV and 89 ms (10 min), 147 µV and 103 ms (15 min), 188 µV and 109 ms (20 min, 0.03 cd·s/m², rod response), and 186 µV and 77 ms (20 min, 3 cd·s/m², maximal combined rod‐cone response). A steady increase in amplitude and implicit time was noted during dark adaptation. No oscillatory potentials could be isolated. Conclusions The use of detomidine hydrochloride sedation and the DTL? microfiber electrode allowed the recording of good quality ERGs. This protocol should permit the detection of functional problems in the retina without the risk involved with general anesthesia.     

Fluoroscopic and endoscopic localization of an esophagobronchial fistula in a dog

A 10-month-old, intact male Chihuahua presented for a 7-month history of regurgitation and coughing. Survey radiographs revealed a soft-tissue opacity within the distal esophagus. A contrast study confirmed the presence of an esophagobronchial fistula. Endoscopic removal of foreign material within the esophagus allowed for visualization of an esophageal diverticulum. Bronchoscopic examination revealed the presence of an abnormal opening in a right caudal tertiary bronchus. Passage of a cardiac guidewire was accomplished, confirming the presence of the fistula and aiding its subsequent surgical removal.     

Antegrade pyelography for suspected ureteral obstruction in cats: 11 cases (1995-2001)

OBJECTIVE: o determine sensitivity and specificity of radiography, ultrasonography, and antegrade pyelography for detection of ureteral obstructions in cats. DESIGN: Retrospective study. ANIMALS: 11 cats. PROCEDURE: Medical records of cats that had radiography, ultrasonography, and antegrade pyelography performed for suspected ureteral obstructions were examined. Ultrasound-guided pyelocentesis and fluoroscopic-assisted antegrade pyelography were performed on 18 kidneys in 11 cats. Obstructive ureteral lesions were confirmed in all cats by surgical or necropsy examination. Sensitivity and specificity of survey radiography, ultrasonography, and antegrade pyelography for identification of ureteral obstructions were calculated. Surgical or necropsy findings were used as the standard for comparison. RESULTS: All cats were azotemic. Mean +/- SD serum creatinine and BUN concentrations were 10.2 +/- 6.1 and 149 +/- 82 mg/dL, respectively. Fifteen of 18 ureters were found to be obstructed at surgery or necropsy. Sensitivity and specificity were 60 and 100% for radiography and 100 and 33% for ultrasonography, respectively, in identification of ureteral obstructions. Leakage of contrast material developed in 8 of 18 kidneys during antegrade pyelography and prevented diagnostic interpretation in 5 of 18 studies. For the 13 diagnostic studies, specificity and sensitivity were 100% by use of the antegrade pyelography technique. Correct identification of the anatomic location of the ureteral obstruction was obtained in 100% of diagnostic antegrade pyelography studies and in 60% of radiography or ultrasonography studies. CONCLUSIONS AND CLINICAL RELEVANCE: Antegrade pyelography can be a useful alternative in the diagnosis and localization of ureteral obstructions in azotemic cats, although leakage of contrast material may prevent interpretation of the study.     

Evaluation of an ear cleanser for the treatment of infectious otitis externa in dogs

Thirty-one ears (16 dogs) with otitis externa originating from bacterial or yeast infections were enrolled in a study to evaluate the in vivo efficacy of an ear cleanser containing 2.5% lactic acid and 0.1% salicylic acid for the treatment of infectious otitis externa. The affected ears were treated with the ear cleanser twice daily for 2 weeks and evaluated after 1 and 2 weeks of treatment. The ear cleanser was effective in resolution of infection in 67.7% of the ears, and clinical signs of infectious otitis externa were significantly reduced within 2 weeks.     

Comparison of the environmental survival characteristics of Salmonella Dublin and Salmonella Typhimurium

To examine possible correlations in bovine Salmonella isolates between environmental survival and serovar-associated epidemiological patterns, bovine field isolates of Salmonella serovars Typhimurium and Dublin (two each) were inoculated into bovine faeces slurry and tested monthly by culture for survival during a six-month period of storage at a variable ambient temperature in a disused animal transporter. Low moisture conditions, where the slurry was dried onto wooden dowels, increased detectable survival of a low-level inoculum by up to five months, compared with wet slurry. A more modest increase of survival time was seen with storage of wet slurry under refrigeration at 4°C. Under both dry and wet conditions, the concentration of culturable Salmonella Typhimurium declined at a slower rate than did that of Salmonella Dublin. Salmonella that was naturally contaminating bovine faeces from farms with Salmonella Typhimurium did not show superior survival times compared with Salmonella Typhimurium that had been artificially inoculated into samples. The differing survival characteristics of the two serovars that was observed in environmental faeces may complement their different modes of infection in cattle. Salmonella Dublin, being a bovine host-adapted strain that establishes chronic infection in some animals, may have less need to survive for a prolonged period outside of its host than does Salmonella Typhimurium.     

Effects of zinc on tissue uptake and toxicity of lead in Sprague Dawley rat

Lead (Pb) exposure occurs together with other metals including zinc (Zn). This study investigated the impact of Zn on Pb tissue accumulation and Pb-induced toxicities. Animals (n=6 rats per group) were exposed to lead acetate (PbAc) or a combination of PbAc and zinc acetate (ZnAc) under the following groups: control (deionized water), low PbAc [12 mg/kg PbAc (3 mg PbAc/rat/day)], low PbAc–ZnAc [12 mg/kg PbAc (3 mg PbAc/rat/day) + 0.2 mg ZnAc/rat/48 hr], high PbAc [120 mg/kg (30 mg PbAc/rat/day)], and high PbAc–ZnAc [120 mg/kg (30 mg PbAc/rat/day) + 1 mg ZnAc/rat/48 hr] for 8 weeks. A significant reduction in body weight gain was observed in the high PbAc group relative to the control group. Muscles and testes both had reduced and increased Pb uptake in low PbAc–ZnAc and high PbAc–ZnAc groups compared to PbAc only groups, respectively. Bone Pb levels in the high PbAc–ZnAc group were lower than the high PbAc group. Zinc co-administration attenuated Pb-induced inhibition of delta aminolaevulinic acid dehydratase enzyme and enhanced catalase enzyme activity at a high level of exposure. Moreover, ZnAc seems to have minimized the effects of Pb-induced mRNA dysregulation in antioxidant and antiapoptotic enzymes encoding genes. Heme oxygenase-1 was downregulated in the kidney and brain in the low PbAc group. Liver glutathione peroxidase and thioredoxin reductase-1 were downregulated in the high PbAc group. These findings suggest that zinc co-administration with lead may partially mitigate against Pb-induced toxicities.