Blood supply of the sinus node artery in beagle dogs

Summary Postmortem coronary angiography was performed in 20 beagles and 15 mongrels, and the origin and distribution of the sinus node arteries (SNAs) were subsequently investigated using soft X-ray radiography, the tissue clearing method, and histological examination. In 19 of 20 beagles, the SNAs consisted of a single atrial branch originating from the right coronary artery, and the distribution pattern of the atrial branch seemed to be uniform. In contrast, the following three different patterns were recognized in the atrial branches forming the SNAs of mongrels: (1) distribution by two atrial branches, i.e., one originating from the right coronary artery and the other from the left circumflex artery, (2) dual distribution by two atrial branches originating from the right coronary artery, and (3) distribution by a single atrial branch originating from the right coronary artery or from the left circumflex artery. In 26 of the 30 dogs which were histologically examined, the SNAs ran outside of the sinus node and were not centrally located. In the beagles, the proximal atrial branch from the right coronary artery reached the atrioventricuolar node area and supplied blood to the atrioventricular node together with the arterial branches derived from the anterior septal artery and posterior septal artery. In addition, the arterial branch of the SNAs reached the atrioventricular junction area. These findings should contribute to clinical, pharmacological, and pathological studies of the cardiovascular system, including studies on cardiac arrhythmias in beagles.     

Beagle sciatic nerve regeneration across a 30 mm defect bridged by chitosan/PGA artificial nerve grafts

Longitudinally oriented microstructures are essential for a nerve scaffold to promote the significant regeneration of injured peripheral axons across nerve gaps. In the current study, we present a novel nerve-guiding collagen-chitosan (CCH) scaffold that facilitated the repair of 30 mm-long sciatic nerve defects in beagles. The CCH scaffolds were observed with a scanning electron microscope. Eighteen beagles were equally divided into CCH group, autograft group and non-graft group. The posture and gait of each dog was recorded at 12 and 24 weeks after surgery. Electrophysiological tests, Fluoro-Gold retrograde tracing test, Histological assessment of gastrocnemius and immunofluorescent staining of nerve regeneration were performed. Our investigation of regenerated sciatic nerves indicated that a CCH scaffold strongly supported directed axon regeneration in a manner similar to that achieved by autologous nerve transplantation. In vivo animal experiments showed that the CCH scaffold achieved nerve regeneration and functional recovery equivalent to that achieved by an autograft but without requiring the exogenous delivery of regenerative agents or cell transplantation. We conclude that CCH nerve guides show great promise as a method for repairing peripheral nerve defects.     

比格犬一种新雌激素β受体可变剪切体的克隆及鉴定

目的对比格犬雌激素β受体的新剪切体进行克隆与鉴定。方法以比格犬垂体组织为模板,用RT-PCR方法从垂体组织中扩增雌激素β受体,电泳确定新剪切体的存在情况.并对其进行克隆和序列测定.结果利用设计的引物得到2条明显电泳条带,通过测序表明其中一种为新的可变剪切体,目前此可变剪切体尚未见报道。结论得到了雌激素β受体的一种新的可变剪切体,有助于研究雌激素β受体可变剪切体的功能及其在生殖调控过程中的作用。     

A novel missense mutation responsible for factor VII deficiency in research Beagle colonies

BACKGROUND: Canine factor VII (cFVII) deficiency, an autosomal recessive trait originally identified in research Beagles, is associated with a mild to moderate bleeding tendency. OBJECTIVE: Our aim was to identify and characterize the mutation causing cFVII deficiency. METHODS: In order to sequence the coding regions of the cFVII gene, we cloned the cFVII cDNA. Genomic DNA and plasma from FVII-deficient Beagles and obligate carriers were utilized. RESULTS: In all FVII-deficient dogs, we identified a single causative G to A missense mutation in exon 5, encoding the second epidermal growth factor-like domain, resulting in substitution of glycine 96 by glutamic acid, with plasma FVII coagulant activity of Beagles. In vitro expression indicated that the majority (96%) of cFVII-G96E protein was retained intracellularly. In addition, analysis of purified recombinant wild-type and mutant cFVII proteins demonstrated reduced activity of the mutant (< 2%) compared with wild-type. Rotational thromboelastometry revealed a severe impairment of clotting activity in affected Beagles, and heterozygotes also exhibited changes in coagulation-based assays. Using a mutation-specific polymerase chain reaction/restriction digest that allows rapid identification of the G96E mutation, we surveyed a US research Beagle colony and identified a mutant allelic frequency of 31%. CONCLUSIONS: We have identified a single causative mutation for cFVII deficiency that may have implications for pharmacotoxicologic research, because reduced FVII coagulant activity may alter hemostatic and/or cardiovascular endpoints in this commonly used animal species.     

Hydroxylation of phenacetin by beagle liver microsomes

Summary Phenacetin was incubated with liver microsomes from beagles pretreated with phenobarbital or 3,4-benzyprene. SKF-525 A at various concentrations was added to incubations containing 1 mM phenacetin.The following products of primary microsomal hydroxylation were searched for: paracetamol, 2-hydroxyphenacetin, 3-hydroxyphenacetin, and N-(4-ethoxyphenyl)-glycolamide.N-(4-ethoxyphenyl)-glycolamide was found in microsomes of 3,4-benzpyrenetreated animals, whereas no 2-hydroxy- or 3-hydroxyphenacetin was observed.The O-dealkylation rate of phenacetin, leading to paracetamol, showed an apparent V _max of 1.2, 2.0, and 9.3 nmol per min per mg protein in the untreated, phenobarbital, or 3,4-benzpyrene treated groups, respectively. The apparent K _m of phenacetin (0.25 mM) remained unaffected by either treatment. About 1.5 mM SKF-525 A caused half maximum inhibition of paracetamol formation.     

Cytological study on the anterior pituitary of beagle bitches treated subcutaneously with progesterone for 13 weeks

The effects of subcutaneous administration of 25 mg/kg/day progesterone for 13 weeks on the pituitary glands of immature ovariectomised and mature intact beagle bitches were studied using a histochemical technique. In the treated animals the most striking effect was an apparent increase in the relative number of prolactin producing cells (PRL cells) when compared with the controls, whether mature in the anoestrous or prooestrous phases of the cycle or immature (intact or ovariectomised).While the relative number of PRL-producing cells in the progesterone-treated bitches was comparable to that in the controls in the metoestrous phase of the cycle, in the former they showed more morphological signs of intense secretory activity, accompanied in most cases by a rise in serum prolactin levels. The accelerated secretory activity of PRL cells accounts for the capacity of progesterone to induce excessive mammary gland development.In the progesterone treated bitches and in the control animals in the metoestrous phase of the cycle, the STH cells diminished in number. Moreover in these animals, the number of STH and ACTH cells showing morphological signs of secretory activity was slightly more than in the other animal troups.The gonadotrophs exhibited involutionary changes under treatment with progesterone.     

The effects of chronic dietary calcium supplementation on bone mineral density in ovariectomized Beagles

Summary Oral calcium tablets were given daily for 180 days to ovariectomized Beagle dams (n=4). Total serum calcium, and bone mineral content of midshaft femur were measured and compared to that of the controls (ovariectomized alone, n=4). The bone mineral density was significantly higher in the calcium supplemented dogs (p<0.01).     

肝脏CT灌注成像与门静脉压力相关性的动物实验研究

目的:探讨正常比格犬门静脉压力与肝脏CT血流灌注参数的相关性。方法:采用螺旋CT对24只犬行肝脏灌注成像扫描,去卷积法计算肝脏血流灌注参数,包括血流量(blood flow,BF)、血容量(blood volume,BV)、平均通过时间(mean transit time,MTT)、肝动脉分数(hepatic arterial fraction,HAF)、肝动脉灌注量(hepatic arterial perfusion,HAP)、门静脉灌注量(portal venous perfusion,PVP)。扫描后3d内开腹,采用玻璃水柱法测定门静脉压力。利用直线回归与相关分析门静脉压力与肝脏CT血流灌注参数的相关性。结果:(1)正常比格犬实测门静脉压力值为(13.57±1.15)cmH2O。(2)正常比格犬门静脉压力与BF、PVP呈负相关,与HAF呈正相关,其中以PVP相关性最显著(r=-0.764,P<0.05),两者关系的直线回归方程为Y=16.507-0.037X。结论:肝脏CT灌注成像为无创、有效监测门静脉压力提供了一种新途径。     

细胞因子治疗4.5Gyγ射线照射比格犬造血损伤的机制初探

目的 探讨多种细胞因子配伍应用治疗4.5 Gy γ射线照射比格犬造血系统损伤的作用及可能机制。方法 16只比格犬均给予4.5 Gy ⁶⁰Co γ射线全身照射,随机分为照射对照、综合对症和细胞因子3组。细胞因子组在综合对症支持治疗的基础上应用rhG-CSF、rhIL-11和rhIL-2联合治疗,采用流式细胞术检测外周血中CD34+细胞含量、有核细胞周期及凋亡比例。结果 4.5 Gy γ射线照射犬外周血中CD34+细胞含量在照射后1 d明显下降(照射对照组和综合对症组分别为照前值的61.3%和52.1%),G₀/G₁期有核细胞比例增加(分别为99.27%和99.49%),且凋亡率(分别为26.93%和21.29%)和坏死率(分别为3.27%和4.14%)明显升高(与照前值比较, P<0.05);而经过细胞因子治疗后,外周血中CD34+细胞含量在照射后1 d即明显升高(为照前值的135.6%),G₀/G₁期有核细胞比例(99.71%)进一步增加,其凋亡率(5.66%)和坏死率(1.60%)明显低于照射对照和综合对症组。结论 本研究的细胞因子组合可能通过动员骨髓中CD34+细胞到外周血,使细胞周期阻滞在G₀/G₁期,减少细胞凋亡,从而促进极重度骨髓型急性放射病犬造血功能的恢复。     

抗肿瘤血清胸腺因子9肽的急性毒性和遗传毒性

目的： 观察抗肿瘤创新药血清胸腺因子9肽是否存在急性毒性和遗传毒性,为临床用药提供安全性依据。方法： 小鼠、大鼠和Beagle犬一次性注射给予70.0 mg/kg血清胸腺因子9肽进行急性毒性试验,采用Ames试验、中国仓鼠肺成纤维细胞（CHL）染色体畸变试验和小鼠骨髓细胞微核试验组合进行血清胸腺因子9肽的遗传毒性试验。结果： 一次性注射给药后3种动物精神好、行为正常,均未出现兴奋或抑制体征,均未发现动物急性毒性表现;Ames试验在1~5 000 μg/皿浓度各菌株的平均回变菌落数均与溶剂对照组相似,未见明显增加（P>0.05）;CHL染色体畸变试验在1 400~5 600 μg/mL剂量范围内染色体畸变率均≤3%,与溶剂对照组比较,差异均无统计学意义（P>0.05）;微核试验在17.5~70.0 mg/kg剂量组的微核细胞率均<2.0‰,与溶剂对照组（1.2‰）比较,差异均无统计学意义（P>0.05）。结论： 小鼠、大鼠和Beagle犬对血清胸腺因子9肽的最大耐受剂量>70.0 mg/kg,按体质量计算相当于临床人拟用量的930倍;在本试验剂量范围内未见血清胸腺因子9肽的急性毒性和遗传毒性作用。