Evaluation of left ventricular function with cardiac magnetic resonance imaging and echocardiography after administration of dobutamine and esmolol in healthy beagle dogs

Unlike echocardiography, cardiac magnetic resonance imaging (cardiac MRI) results in a near-exact assessment of cardiac structures and function. However, most veterinary studies have focused on dogs with normal cardiac function. We hypothesized that there would be significant differences in cardiac measurements between cardiac MRI and echocardiography when left ventricular (LV) function was abnormal. This study was undertaken to compare measurements of LV function produced by cardiac MRI and echocardiography in dogs whose LV function was altered by pharmacological agents. This study was conducted with six healthy beagle dogs. We increased left ventricular contractility by administration of dobutamine; we decreased cardiac contractility with esmolol. Stroke volume measurements were made by using both cardiac MRI and echocardiography under seven different conditions with general anesthesia: control, three doses of esmolol (100, 200, and 500 µg/kg/min), and three doses of dobutamine (10, 20, and 50 µg/kg/min). Experiments involving each condition were conducted at least 1 week apart. When LV contractility was normal, ejection fraction (EF) and stroke volume (SV), as measured by echocardiography and cardiac MRI, were not significantly different. However, when contractility was changed by pharmacological agents, EF and SV were overestimated by echocardiography, compared to MRI. Evaluation of cardiac function in patients treated with pharmacological agents should be conducted carefully because EF and SV measured by echocardiography can be overestimated, compared with EF and SV obtained by cardiac MRI.     

Clinical,pathologic, and toxicologic characterization of Salvia reflexa (lance-leaf sage) poisoning in cattle fed contaminated hay

Salvia reflexa (lance-leaf sage)-contaminated alfalfa hay was fed to ~500 mixed-breed beef cattle. Within hours of exposure, nearly half of the cattle developed lethargy, anorexia, depression, and recumbency, followed by bellowing, colic, and death. Even though the uneaten contaminated hay was removed the first day, nearly 100 animals died within the first 48 h. Three of these cattle were examined postmortem, and tissues and hay samples were collected for microscopic and chemical analysis. Several days later, a smaller number of the clinically poisoned cattle developed neurologic disease with aberrant behavior, aggression, icterus, blindness, exhaustion, and death. A total of 165 cattle were fatally poisoned. Poisoned cattle had swollen, dark, mottled livers that had a prominent nutmeg-like lobular pattern on cut section. Histologically, there was severe centrilobular-to-panlobular hepatic necrosis with marked hepatocellular swelling, degeneration, and necrosis. The surviving cattle developed liver disease characterized by altered serum biochemical analyses and microscopic hepatocellular degeneration and necrosis. In subsequent biopsies and analysis, these lesions resolved within 6–7 mo. After confirming toxicity of the hay in cattle, goats, and mice, followed by a mouse bioassay–guided chemical fractionation process, Salvia reflexa was identified as the contaminant in the hay responsible for the hepatotoxicity. S. reflexa has not been reported previously to cause fatal hepatotoxicity in livestock in North America, to our knowledge.     

The effects of maxillary nerve block,ethmoidal nerve block and their combination on cardiopulmonary responses to nasal stimulation in anesthetized Beagle dogs

ObjectiveTo describe an approach for ethmoidal nerve block (E_BLOCK) and to compare the effects of a maxillary nerve block (M_BLOCK), E_BLOCK and their combination (M-E_BLOCK) on heart rate (HR), systolic (SAP), mean (MAP), diastolic (DAP) arterial pressures and respiratory rate (f_R) during nasal stimulation in dogs.Study designProspective, blinded, randomized, crossover placebo-controlled study.AnimalsBeagle dogs (five cadavers, nine live dogs), with a median (interquartile range) weight of 10.5 (10.3–11.0) kg.MethodsThe accuracy of iohexol injections (each 1 mL) at the maxillary and ethmoidal foramina in cadavers was evaluated using computed tomography. Then, anesthetized dogs were administered four bilateral treatments separated by 1 week, saline or 2% lidocaine 1 mL per injection: injections of saline at the maxillary and ethmoidal foramina (Control), injections of lidocaine at the maxillary foramina and saline at the ethmoidal foramina (M_BLOCK), injections of saline at the maxillary foramina and lidocaine at the ethmoidal foramina (E_BLOCK) and injections of lidocaine at all foramina (M-E_BLOCK). The ventral nasal meatus was bilaterally stimulated using cotton swabs, and HR, SAP, MAP, DAP and f_R were continuously recorded. Values for each variable were compared before and after stimulation using Wilcoxon signed-rank test. Changes in variables among treatments were analyzed using Mann–Whitney U and Kruskal–Wallis tests (p ≤ 0.05).ResultsComputed tomography revealed iohexol distribution around the openings of the target foramina in all cadavers. In living dogs, HR, SAP, MAP, DAP and f_R significantly increased after stimulation within each treatment (p < 0.03). Physiologic responses were significantly attenuated, but not absent, in the M-E_BLOCK [HR (p = 0.019), SAP, MAP, DAP and f_R (all p ≤ 0.001)] compared with those in the Control.Conclusions and clinical relevanceConcurrent injections of lidocaine at the maxillary and ethmoidal foramina attenuated HR, arterial pressure and f_R responses to nasal stimulation in Beagle dogs.     

Association between weight change during initial chemotherapy and clinical outcome in dogs with multicentric lymphoma

The majority of the known prognostic factors in dogs with lymphoma have been evaluated before treatment commences or at the time of diagnosis. Prognostic factors evaluated during the initial phase of treatment are less described but may provide important clinical information. In this retrospective study, 82 canine lymphoma patients were categorized according to the weight change between diagnosis and after 5 weeks of chemotherapy. Dogs that gained greater than 5% or lost greater than 5% of initial body weight were categorized as increased‐ or decreased‐weight groups, respectively. Those in which weight changed less than 5% were categorized as the maintained‐weight group. The median progression‐free survival (PFS) in the increased‐weight group, maintained‐weight group and decreased‐weight group was 226, 256 and 129 days, respectively. The decreased‐weight group had significantly shorter PFS than the increased and maintained groups (P = .023, P = .003, respectively). The median survival time (ST) in the increased‐weight group, maintained‐weight group and decreased‐weight group was 320, 339 and 222 days, respectively. There was no significant difference in ST among the three groups (P = .128). In Cox‐regression results, weight change group and initial body weight were significant risk factors associated to PFS (P = .007, P = .001, respectively) while only patient's initial body weight was a significant risk factor to ST (P = .013). In conclusion, evaluation of initial body weight and weight changes over time can provide valuable information regarding PFS and ST in dogs with multicentric lymphoma.     

部分地区猪细环病毒1型感染的流行情况调查

猪细环病毒1型是近年来发现的又一种环状DNA病毒,可能存在潜在致病作用。为了初步了解其流行情况,用PCR技术和ELISA技术对来自京津冀、华东与华南地区578头保育猪血清样品进行了检测。结果显示,猪细环病毒1型的核酸与抗体的猪场阳性率均为100%;核酸阳性率为73.88%,抗体阳性率为78.72%,二者之间无显著差异（P>0.05）。进一步分析发现,猪细环病毒1型的核酸阳性率和抗体阳性率都超过50%的猪场达到86.67%,都超过80%的占53.33%。调查结果表明,猪细环病毒1型感染在我国部分地区普遍流行,其在多数猪场的感染率很高。     

苯并芘对猪卵母细胞SHH信号通路影响的研究

如今空气污染问题仍广泛存在,其中苯并芘（Benzo （a） pyrene,BaP）是一种常见的空气污染物,对人和动物的健康具有严重影响。据报道,BaP可以显著降低卵母细胞IVM （卵母细胞体外成熟）能力,但机制尚不清楚。因此,本研究在猪卵母细胞IVM培养液中添加不同浓度BaP （50 μM、100 μM、200 μM）检测其对卵母细胞IVM能力的影响,并检测此过程SHH信号通路相关基因和蛋白的表达。结果显示50 μM BaP处理组卵母细胞IVM能力显著低于对照组（76.5 vs 68.1,P<0.05）,并随着BaP浓度增加进一步下降。同时,qPCR和免疫荧光染色检测发现,50 μM BaP处理组卵母细胞中SHH信号通路相关基因mRNA和蛋白表达量,均显著低于对照组（P<0.05）。因此,本研究初步证明BaP可能通过破坏SHH信号通路降低猪卵母细胞IVM能力。     

供油提前角对甲醇发动机性能及排放的影响

利用在缸内加装电热塞的ZS1115单缸柴油,实现纯甲醇(M100)燃料的扩散燃烧,利用柴油机热效率高的优点,提高甲醇燃料的能量转换效率。通过改变供油提前角,研究不同供油提前角对甲醇发动机性能及排放的影响,并与原单缸柴油机燃用0#柴油进行对比。试验结果表明:供油提前角对甲醇发动机动力性、经济性及排放均有影响。与原机燃用0#柴油相比,燃油消耗率上升,使用成本降低;HC排放量升高,CO和NOX排放量降低。供油提前角提前4°CA时CO排放最少,最低平均减少23.89%;供油提前角退后2°CA时NOX排放最少,最低平均减少94.74%。     

黄淮海地区大豆生产机械化现状与发展趋势

机械化在大豆全程生产中发挥着重要作用。为此,针对黄淮海地区大豆机械化生产现状,分析了目前大豆机械化生产中存在的问题,对大豆产业发展,从"种子处理技术""机械化精密平播免中耕技术""科学施肥,合理使用杀虫剂和除草剂""大力推广大豆机械化收获技术"等方面简要阐述黄淮海地区大豆生产全程机械化的发展趋势。     

宽幅高效离心式双圆盘撒肥机设计与试验

为解决现有水旱田撒肥机械作业效率低、撒肥量调节技术落后、施肥均匀性稳定性差等实际问题,设计了一种同轴驱动的离心式双圆盘撒肥机。介绍了整机结构与工作参数,研究设计了撒肥传动系统、撒肥盘结构、排肥量液压调节装置等,并确定了关键结构和参数,同时进行了试验研究。试验结果显示,推肥板推肥角度-20°~30°可调,撒肥幅宽达到50m,总排肥量稳定性变异系数低于6%,施肥均匀性变异系数低于16%。研究结果表明,撒肥机工作性能稳定、撒肥量可控、抛撒均匀,整机设计满足水旱田宽幅高效撒肥作业要求。