Age and distraction are determinants of performance on a novel visual search task in aged Beagle dogs

Aging has been shown to disrupt performance on tasks that require intact visual search and discrimination abilities in human studies. The goal of the present study was to determine if canines show age-related decline in their ability to perform a novel simultaneous visual search task. Three groups of canines were included: a young group (N = 10; 3 to 4.5 years), an old group (N = 10; 8 to 9.5 years), and a senior group (N = 8; 11 to 15.3 years). Subjects were first tested for their ability to learn a simple two-choice discrimination task, followed by the visual search task. Attentional demands in the task were manipulated by varying the number of distracter items; dogs received an equal number of trials with either zero, one, two, or three distracters. Performance on the two-choice discrimination task varied with age, with senior canines making significantly more errors than the young. Performance accuracy on the visual search task also varied with age; senior animals were significantly impaired compared to both the young and old, and old canines were intermediate in performance between young and senior. Accuracy decreased significantly with added distracters in all age groups. These results suggest that aging impairs the ability of canines to discriminate between task-relevant and -irrelevant stimuli. This is likely to be derived from impairments in cognitive domains such as visual memory and learning and selective attention.     

改良Nance弓在矫治上颌腭侧埋伏尖牙的作用

目的 探讨改良Nance弓在矫治上颌腭侧埋伏尖牙时矫治力方向设计及支抗设计的作用.方法 7例单侧上颌腭侧埋伏尖牙均采用外科-正畸联合治疗.手术暴露埋伏尖牙牙冠,粘接舌侧扣;戴入改良Nance弓,利用改良Nance弓位于腭侧不锈钢丝上的附钩,先将尖牙冠向后牵引绕过侧切牙的牙根,直到位于正常尖牙间隙的腭侧,如尖牙间隙不足,则粘结上颌托槽,预备尖牙间隙;再采用直丝弓技术将埋伏尖牙向唇侧移动,排齐牙列,调整咬合关系.对治疗后牙齿的松动度、牙髓活力等进行观察.结果 7位埋伏尖牙均被牵引至牙弓的正常位置;牙髓活力测试正常,牙周附着良好.结论 改良Nance弓在矫治上颌腭侧埋伏尖牙时,在矫治力方向设计和支抗控制方面有独特优点和作用.     

Preliminary Results with an Apico-Aortic Valved Conduit (AAVC) Using Polyurethane and Aortic Allograft Valves

Stenosis of the left ventricular outflow tract is one of the most frequent congenital cardiac anomalies in dogs. The subvalvular stenosis is described as a ring of fibrous tissue located in the left ventricular outflow tract immediately below the aortic valve. The best method of surgical treatment in dogs seems to be relief of the aortic obstruction with a ventricular aortic prosthesis. A new trileaflet valve manufactured out of polyurethane has been developed. For the conduit a woven Dacron graft has been used. In 5 male dogs a valved conduit was implanted between the apex of the left ventricle and the aorta thoracica without using hypothermia and/or cardiopulmonary bypass. Four dogs survived the surgical procedure and showed no clinical symptoms postoperatively. Blood flow through the conduit was demonstrated postoperatively by angiocardiography for a maximum of 22 days, the longest surviving time being 8 weeks. Trials for the replacement of the artificial valve in the conduit by a canine aortic allograft valve are in progress. Studies were done with the cryopreservation of fresh aortic valves. Sterilization, cryoconservation, and storage methods for the allograft are described     

犬乳腺常见肿瘤的组织病理学观察

目的 对收集到的犬乳腺肿瘤进行病理学分类及描述,以期为乳腺肿瘤的诊断和治疗提供依据.方法 将手术治疗切除的犬乳腺肿物,制成切片,根据病理学观察结果,进行分类描述.结果 从良、恶性肿瘤逐一对收集到的肿瘤病理学形态进行描述,囊括了犬乳腺的常发肿瘤及不常见的肿瘤.结论 不同分类的肿瘤其病理学形态相差很大,在应用犬类进行相关研究时应该引起注意.     

Bacteria detected after instrumentation surgery for pyogenic vertebral osteomyelitis in a canine model

Objective

This study was designed to identify the presence, type and origin of bacteria adjacent to the metal implant in the infected region in a canine model of pyogenic vertebral osteomyelitis treated with single-stage anterior autogenous bone grafting and instrumentation.

Methods

Dogs with pyogenic spondylodiscitis underwent one-stage debridement, autogenous bone grafting and titanium plate instrumentation and perioperative antibiotic therapy. The implants and adjacent vertebral bones were removed surgically at various postoperative time points (4, 8, 12 and 24 weeks) for bacteria detection. Bacteria were detected from retrieved spinal implants as well as surrounding bones by culture and/or pyrosequencing methods in 17 (85 %) of all 20 animals. The positive rate for bacteria presence was 45 % by culture and 80 % by pyrosequencing method.

Results

Radiological or macroscopic examination showed no signs for infection recurrence in any animal regardless of bacteria presence at the surgical site. However, organism identical with the causative bacterium for spinal infection was found in only two of nine culture-positive animals.

Conclusion

Within the confines of the study, the use of metallic implants in an infected area did not lead to a clinically relevant infection although bacteria may exist at the surgical site. The use of metallic implants in an infected area of the spine is safe. The metallic implants may not be the “culprit” for the persistence or recurrence of infection.     

Liver biomarker and in vitro assessment confirm the hepatic origin of aminotransferase elevations lacking histopathological correlate in beagle dogs treated with GABAA receptor antagonist NP260

NP260 was designed as a first-in-class selective antagonist of α4-subtype GABA_A receptors that had promising efficacy in animal models of pain, epilepsy, psychosis, and anxiety. However, development of NP260 was complicated following a 28-day safety study in dogs in which pronounced elevations of serum aminotransferase levels were observed, although there was no accompanying histopathological indication of hepatocellular injury. To further investigate the liver effects of NP260, we assayed stored serum samples from the 28-day dog study for liver specific miRNA (miR-122) as well as enzymatic biomarkers glutamate dehydrogenase and sorbitol dehydrogenase, which indicate liver necrosis. Cytotoxicity assessments were conducted in hepatocytes derived from dog, rat, and human liver samples to address the species specificity of the liver response to NP260. All biomarkers, except ALT, returned toward baseline by Day 29 despite continued drug treatment, suggesting adaptation to the initial injury. In vitro analysis of the toxicity potential of NP260 to primary hepatocytes indicated a relative sensitivity of dog > human > rat, which may explain, in part, why the liver effects were not evident in the rodent safety studies. Taken together, the data indicate that a diagnostic biomarker approach, coupled with sensitive in vitro screening strategies, may facilitate interpretation of toxicity potential when an adaptive event masks the underlying toxicity.     

建立犬心房颤动模型的研究

用自制健索钩刀破坏25条犬部分二尖瓣腱索，造成中等程度二尖瓣关闭不全，建立心房颤动（AF）动物模型。术后12周内每2周1次行超声心动图及电生理检查，每次检查后用Burst刺激法诱发AF。术后2周左房前后径增加（22．70±2．31mmvs20．39±3．08mm，P＜0．05），术后4周左房面积增加（7．01±1．91cm2vs5．63±2．05cm2，P＜0．05）。术后4周P波时限延长（61．00±5．07msvs48．75±8．82ms）、高位右房有效不应期缩短（102．67±11．00msvs133．33±14．97ms），P均＜0．01。术后12周80％（8／10）的犬可诱发出持续时间＞5min的AF。左、有房AF波周期无显著差异（102．50±17．89msvs116．60±18．24ms，P＞0．05）。通过破坏二尖瓣腱索造成犬急性二尖瓣关闭不全，手术后随时间延长，动物表现在房扩张及右房有效不应期缩短和心房内传导时间延长，此与临床上瓣膜病引起的AF有一定的对应性，因而是研究AF电生理的良好模型。     

Differing roles of protein kinase C-zeta in disruption of tight junction barrier by enteropathogenic and enterohemorrhagic Escherichia coli

BACKGROUND & AIMS: Enteropathogenic Escherichia coli and enterohemorrhagic E. coli harbor highly homologous pathogenicity islands yet show key differences in their mechanisms of action. Both disrupt host intestinal epithelial tight junctions, but the effects of enteropathogenic E. coli are more profound than those of enterohemorrhagic E. coli. The basis for this is not understood. The atypical protein kinase C isoform, protein kinase C-zeta, associates with and regulates the tight junction complex. The aim of this study was to compare the role of protein kinase C-zeta in the disruption of tight junctions after infection with enteropathogenic E. coli and enterohemorrhagic E. coli. METHODS: Model intestinal epithelial monolayers infected by enteropathogenic E. coli or enterohemorrhagic E. coli were used for these studies. RESULTS: Neither bisindolylmaleimide nor G?6976, which block several protein kinase C isoforms but not protein kinase C-zeta, protected against the decrease in transepithelial electrical resistance after enteropathogenic E. coli infection. Rottlerin at concentrations that block novel and atypical isoforms, including protein kinase C-zeta, significantly attenuated the decrease in transepithelial electrical resistance. The specific inhibitory peptide, myristoylated protein kinase C-zeta pseudosubstrate, also significantly decreased the enteropathogenic E. coli -associated decrease in transepithelial electrical resistance and redistribution of tight junction proteins. In contrast to enteropathogenic E. coli, the level of protein kinase C-zeta enzyme activity stimulated by enterohemorrhagic E. coli was transient and minor, and protein kinase C-zeta inhibition had no effect on the decrease in transepithelial electrical resistance or the redistribution of occludin. CONCLUSIONS: The differential regulation of protein kinase C-zeta by enteropathogenic E. coli and enterohemorrhagic E. coli may in part explain the less profound effect of the latter on the barrier function of tight junctions.     

经心外膜射频消融治疗心房颤动的实验研究

为探讨射频消融治疗心房颤动（简称房颤）的可行性，对１０条犬进行单心房Ｂｕｒｓｔ刺激和药物＋心房电刺激建立房颤模型并进行心房外膜多条径线的消融。结果显示：消融径线为连续和透壁性损伤；消融后药物＋心房电刺激的房颤诱发率和平均持续时间与消融前比较差异有高度显著性（５８％ｖｓ１００％，４．５ｓｖｓ２０３．５ｓ，Ｐ均＜０．０１）；校正窦房结恢复时间和窦性心率分别较消融前明显延长６５％（１２９±５１ｍｓｖｓ７８±３４ｍｓ）和下降１２％（１５０±６３ｂｐｍｖｓ１７０±３５ｂｐｍ），而房室传导功能和心脏功能无显著性变化。提示射频消融治疗房颤是可行的，其主要机制为消融径线有效地分离阻隔了参与房颤折返环的心房肌群。１条犬消融后发生持续性窦性停搏，可能是损伤窦房结动脉所致