一种可控性脊髓爆震伤模型的建立

目的建立实验室条件下的脊髓爆震伤模型,探讨脊髓爆震伤的致伤特点。方法采用单质锰炸药黑索金(RDX)纸壳雷管为爆源,随机取12只家兔,按爆距2、4、8 cm分为3组致伤,同时检测冲击波压强、正压作用时间。另将12只家兔随机分为致伤组和对照组,致伤组家兔按已选定的标准爆距致伤,观察伤后组织学变化。结果爆距2、4、8 cm测得冲击波压强分别为93.4、50.4、33.5 MPa,爆距4 cm时可造成双后肢运动诱发电位(MEP)潜伏期延长1.0 ms或波幅下降50%,而不致家兔死亡。病理学显示脊髓脊髓前角神经元出现明显坏死,髓鞘板层结构紊乱。结论本方法建立的可控性脊髓爆震伤模型简单、安全、有效,适用于实验室条件下的爆震伤研究。     

小型猪渐进性梗阻性黄疸模型的建立

目的建立小型猪慢性渐进性梗阻性黄疸模型，评价其模拟临床渐进性梗阻性黄疸患者的价值。方法开腹手术，将并行有16G注射器针头的胆总管用5％碘酒溶液浸泡处理的10号丝线捆扎后，抽除针头。使胆总管早期部分狭窄，后期组织受化学物质刺激发生无菌性炎症反应、纤维组织修复等病理改变，引发胆管组织慢性纤维瘢痕狭窄，造成渐进性梗阻性黄疸。结果实验动物术后观察28d无死亡，第5—7天逐渐出现黄疸，之后渐重；第28天时的总胆红素较术前明显升高[（1．22±0．41）μmol／L比（125．90±35．77）μmol／L（P〈0．01）]；4周后病理显示胆总管组织发生慢性纤维瘢痕样变，管腔狭窄阻塞。结论本小型猪动物模型模梗阻性黄疸呈渐进性、慢性过程。可重复性强、耐受性好，是比较理想的梗阻性黄疸动物模型。同时，小型猪肝胆系统的生理及解剖结构与人相近，可为临床胆管狭窄和肝门部癌相关研究提供较可靠实验依据。     

不同深度糖尿病大鼠烫伤模型的制备

目的探讨恒温恒压电热烫伤仪制作糖尿病大鼠不同深度烫伤模型的可行性。方法链脲佐菌素诱导正常SD大鼠制作糖尿病大鼠模型，诱导成功1、2、3、4周检测皮肤晚期糖基化终产物、胶原含量，以正常SD大鼠作为对照，判断典型糖尿病性皮肤改变所需的时间。以恒温恒压烫伤仪制作烫伤模型，制模条件为0．5kg压力下，80℃，分别作用时间4．6、12s，48h后取材行苏木素-伊红（HE）染色检测烫伤深度。结果糖尿病大鼠诱导成功后4周，皮肤晚期糖基化终产物含量为（31．40±3．45）U／mg、胶原含量为（12．60±0．57）mg／g，与正常对照组比较差异有统计学意义（P〈0．05），并出现典型的糖尿病性皮肤改变。HE染色烫伤时间4、6、12s时深度依次为浅Ⅱ度、深Ⅱ度和Ⅲ度。结论恒温恒压电热烫伤仪制作糖尿病大鼠不同深度烫伤模型简单、方便，重复性高，为研究糖尿病创面愈合提供较为理想的模型。     

经颅多谱勒检测兔大脑中动脉微血栓栓子的研究

目的应用经颅多谱勒（TCD）动态检测兔血栓栓塞模型大脑中动脉（MCA）的微栓子信号（MES），观察栓子的负荷量与缺血性脑血管病（ICVD）发生的相关性。方法将实验动物随机分为3组，即A组含3—5个栓子，B组含6-10个栓子，C组为生理盐水对照组。采用自体动脉血微栓子建立兔局灶性脑缺血模型同时TCD监测MES。栓塞后6h进行磁共振成像（MRI）及兔脑组织病理观察。结果A、B组TCD均监测到MES；B组MRI的T1WI、T2WI及病理观察见梗死灶，而A组仅在弥散加权成像（DWI）见可疑小缺血灶。结论TCD实时、动态观察微栓子信号，能预测缺血性脑血管病发生的危险性，为临床及早干预治疗提供科学依据。     

单宁酸处理带瓣牛颈静脉的生物学评价

目的从生物学角度评价单宁酸处理的带瓣牛颈静脉是否符合国家医用材料的要求。方法带瓣牛颈静脉经单宁酸处理后按国家医用材料的要求进行浸提液的制备、细胞毒性试验、过敏试验、皮内刺激试验、原发性皮肤刺激试验、溶血试验、急性全身毒性试验及热原试验等生物学评价试验。试验方法均参照《医用有机硅材料生物学评价试验方法》GB／T16175-1996。结果培养的L-929小鼠成纤维细胞经含浸提液的培养基培养后形态良好，增值旺盛，材料细胞毒性评级为0～1。无皮肤刺激反应和过敏反应，皮内刺激试验PⅡ（原发性刺激指数）为0．4，和阴性对照组差异无统计学意义。全身毒性实验受试动物未出现毒性症状。溶血试验溶血率0．7％，符合国家标准（〈5％）。热原试验经中国药品生物制品检定所检定，单宁酸处理后带瓣牛颈静脉无热原（样品批号：060802017）。结论单宁酸处理的带瓣牛颈静脉符合国家医用材料的要求，可以植入人体。     

不同浓度臭氧注入猪椎间盘后氧化效果的实验研究

目的观察低、中、高浓度臭氧注入猪正常椎间盘后不同时间段髓核组织的变化,探索既高效又安全的臭氧浓度,为临床注射臭氧治疗腰椎间盘突出症提供实验依据。方法小型猪10只,于透视下用21G Chiba针刺入猪腰椎间盘中心部,经穿刺针注入臭氧3 ml,重复3次,在椎间孔处注入5 ml于椎旁组织内。其中L5~6,L4~5,L3~4和L2~3分别注入臭氧浓度为90μg/ml,60μg/ml,30μg/ml及无菌空气,L6~S1不进行任何干预,为空白对照。分别在注射后1天、1周、1个月、2个月和3个月后处死动物各2只,在相同时间点进行CT及MR检查。处死后取出椎间盘及椎旁肌肉标本,作大体和光镜下观察,对髓核氧化及退变程度进行量化评分。结果术后3个月内髓核氧化及退变程度评分随时间推移逐渐增高,臭氧浓度越高,增高趋势越明显。术后MRI随访1个月时高浓度组髓核信号T2加权开始减低,其他组不明显。术后2个月注射组所有椎间盘信号均减低,臭氧浓度越高,信号减低越明显。光镜下1天出现髄核细胞的肿胀变性,1周髄核细胞出现与注射浓度正相关的体积缩小和基质含量减少,此后胶原纤维增生,逐渐取代髄核组织,在3个月时,高浓度组髄核干涸的程度,继发纤维化均较中、低浓度组高,并且出现相邻椎体骨性融合。中、高浓度椎旁肌肉注射1周时出现肌纤维肿胀变性及间质黏液变性。结论臭氧浓度越高,髄核的干涸效果越明显,椎间盘退行性变也越明显。高浓度臭氧盘内注射,3个月后椎间盘退变严重,不宜进行临床应用,椎旁肌肉内不宜注射中、高浓度臭氧。     

不同充填材料应用于山羊经皮椎体成形术的组织学研究

目的:研究聚甲基丙烯酸甲酯(PMMA)、磷酸钙人工骨(CPC)和复合重组人骨形态发生蛋白-2的磷酸钙人工骨(rhBMP-2/CPC)在山羊骨质疏松症模型上行经皮椎体成形术(PVP)后的组织学表现。方法:6～8岁雌性山羊8只,均行双侧卵巢切除术,术后4个月建立骨质疏松症模型。在C形臂X线机监视下,随机选取8只山羊的L2-L6的两节椎体行PVP,分别充填PMMA、CPC和rhBMP-2/CPC,保证每只山羊的两节穿刺椎体的充填材料各不相同,术后4个月处死所有动物,取出椎体,组织学观察。结果:8只山羊16个椎体的PVP均成功,共出现4个椎体的渗漏。肉眼观察:PMMA与松质骨界限清晰,一个椎体取材时交界面出现破碎和脱落现象;而CPC和rhBMP-2/CPC与椎体内松质骨界限不清,互相融合生长。HE染色光镜观察:PMMA与骨小梁松散结合,界限明显,未见PMMA吸收和新生骨形成;CPC均匀分布于骨小梁和骨髓组织内,有CPC吸收现象,同时可见有新生软骨样团块形成,并有新生骨组织形成向其中心长入;rhBMP-2/CPC除了CPC的表现外,可见成骨活动活跃。结论:在组织学上,rhBMP-2/CPC和CPC均具有降解活性和骨传导活性,优于PMMA。rhBMP-2/CPC还具有诱导成骨活性,可能成为PVP中强化骨质疏松性椎体的首选充填材料。     

Fluid perfused urethral pressure profilometry and Valsalva leak point pressure: a comparative study in a biophysical model of the urethra

In patient studies the correlation between maximum urethral closure pressure (MUCP) and Valsalva leak point pressure (LPP) is meagre at best (r = 0.22–0.50). We therefore studied the relation between MUCP and LPP in a flexible and extensible model urethra. We applied differently sized pressure zones and different degrees of resistance to a biophysical model urethra by stepwise inflating three types of blood pressure cuff placed around the model. At each degree of resistance we measured detrusor LPP, an in vitro equivalent of Valsalva LPP. Subsequently, we recorded the Urethral Pressure Profile using a water-perfused 5F end-hole catheter at four withdrawal rates and five perfusion rates and calculated MUCP. We tested the dependence of LPP on pressure zone length and MUCP on perfusion rate, withdrawal rate and pressure zone length using analysis of variance. We tested the correlation between LPP and MUCP using Pearson’s correlation coefficient and Linear Regression. LPP did not significantly depend on the pressure zone length (P = 0.80) and increased linearly with increasing cuff pressure. MUCP also increased with increasing cuff pressure, however, MUCP significantly depended (P < 0.01) on perfusion rate, withdrawal rate and pressure zone length. MUCP increased with increasing perfusion rate, and decreased with increasing withdrawal rate. In our model urethra MUCP only accurately reflected urethral resistance for a very limited number of combinations of perfusion rate and withdrawal rate. LPP reflected urethral resistance independent of the type of pressure zone.     

Blunted HPA axis response to stress influences susceptibility to posttraumatic stress response in rats.

BACKGROUND: Posttraumatic stress disorder (PTSD) is associated with low levels of circulating cortisol, and recent studies suggest that cortisol administration may reduce PTSD symptoms. This study investigated the role of cortisol in the manifestation of anxiety- and fear-like symptoms in an animal model of PTSD. METHOD: Magnitude of changes in prevalence of anxiety-like behaviors on the elevated plus-maze and nonhabituated exaggerated startle reaction were compared in three strains of rats exposed to predator stress, with and without prior corticosterone treatment. Extreme behavioral changes in both paradigms implied an extreme behavioral response (EBR), representing PTSD-like symptoms. RESULTS: Lewis rats exhibited greater baseline anxiety-like behaviors and greater stress-induced increases in anxiety-like behaviors than Fischer F344 or Sprague-Dawley rats, with only minor corticosterone increases following stress. Prevalence of EBR was 50% among Lewis rats compared with 10% of Fischer F344 and 25% of Sprague-Dawley rats. Administering corticosterone 1 hour before stress exposure reduced the prevalence of EBR from 50% to 8% in the Lewis rats. CONCLUSIONS: These results suggest that a blunted HPA response to stress may play a causal role in this model of PTSD and that this susceptibility may be prevented by administration of cortisol before stress exposure.     

Electrical induction of spikes in the hippocampus impairs recognition capacity and spatial memory in rats

In clinical studies, interictal EEG spikes (IS) have been associated with numerous neuropsychological abnormalities, ranging from transitory cognitive impairment to epileptic encephalopathies. Understanding the pathophysiological mechanisms of IS has been hampered by the lack of validated animal models. To mimic IS, a stimulating microelectrode was implanted in the ventral hippocampal commissure and a recording microelectrode in the CA1 region of the hippocampus of normal male rats. Spike patterns were induced using a series of electrical pulses 10-30 ms in duration with a frequency of 0.5-2Hz and a current of 0.2mA. The commissural stimulation-evoked population discharges in the hippocampus resembled naturally occurring IS in epileptic rats and, in no cases, resulted in behavioral seizures. For behavioral testing, the Morris water maze, radial arm maze, and object recognition tasks were used. Spikes were induced during sleep between the two sets of water maze trials; during the trials in the radial arm maze task; and prior to the sample phase and during the delay periods in the object recognition task. We demonstrated that rats that received spikes took longer to reach the escape platform in the second set of water maze trials; had significantly more reference errors and required more trials to complete the radial arm maze task; and had lower investigation ratios in the object recognition task. The results indicate that induction of spikes in the hippocampus results in impairment of spatial reference and nonspatial object recognition memory.