新西兰白兔死亡后颅脑CT检查与死亡时间关系的研究

目的采用CT扫描动态观察新西兰白兔死亡后脑组织变化,建立利用CT值、脑组织/颅腔面积比,推断死亡时间(PM I)的研究方法。方法通过耳缘静脉注射空气,建立新西兰白兔死亡模型;于死亡后0~120h,运用CT进行头颅平描;选取颅顶面层测定脑组织CT值、脑组织/颅腔面积比。结果死亡后兔脑组织CT值呈双峰样上升、脑组织/颅腔面积比呈不断下降趋势;建立与死亡时间的回归方程:CT值=47.4780-0.1768T+0.0049T2(T/h,CT值/HU)、面积比=99.7368+0.3098T-0.0118T2/100(T/h)。结论CT扫描检查可准确显示兔脑的死后变化;脑组织消失之前,综合运用CT检查指标可用于准确推断死亡时间。     

钾中毒死亡家兔的尸体化学变化

目的研究家兔钾中毒死亡后的尸体化学变化特征,为钾中毒的法医学鉴定提供参考。方法采用浓度为0.3%和1%的KCl葡萄糖溶液分别以全速和100滴/min的速度输给家兔,至其死亡,测定家兔输液前后血、尿电解质浓度,比较两种不同输液方式所致钾中毒死亡后尸体化学变化特征。结果输钾前后,家兔血清K (SK)浓度升高,血清Na 、Ca2 、Cl-及HCO3-浓度均降低,全血K (TK)及血清Mg2 浓度变化无显著性差异。0.3%KCl组致死输液时间长于1%组(P=0.006),致死输钾量无显著性差异(P=0.062);TK、血清Na 、Mg2 及Cl-浓度变化值具有显著差异,SK、Ca2 、HCO3-浓度变化值无显著差异;尿量和尿液各电解质浓度指标未见显著性差异。结论尸体SK、TK及血清Mg2 浓度升高,有助于钾中毒的法医学死后诊断。     

经颈内动脉介入灌注尸体脑血管显影方法初探

初步建立经颈内动脉介入注射造影剂的尸体脑血管显影方法。经颈总动脉TERUMO 6F鞘管穿刺置入颈内动脉后,分别采取单侧和双侧动脉注入碘造影剂,经CT扫描获取脑部血管图像。单侧颈内动脉显影剂注射后,仅显示同侧大脑内动脉血管走行;双侧颈内动脉显影剂注射后,可获得较完整的脑血管影像。双侧颈内动脉介入方式注射造影剂可以获得较好的尸体脑血管造影效果。     

氯胺酮在家兔体内的毒物代谢动力学

目的研究氯胺酮及其代谢物去甲氯胺酮在家兔体内的毒物代谢动力学特征。方法家兔以氯胺酮0.15g/kg剂量灌胃,分别于给药前和给药后不同时间点收集血液和尿液,血清和尿液中氯胺酮及代谢物用GC-MS法定性、GC-NPD法定量检测,WinNorLin软件拟合房室模型并计算毒物代谢动力学参数。全程记录实验动物主要生命体征变化。结果氯胺酮和代谢物去甲氯胺酮在家兔体内的毒物代谢动力学过程均呈一级动力学特征,符合二室开放模型,氯胺酮毒物代谢动力学方程为ρt=121.760e-0.025t+0.980e-0.002t+4.579 e-0.021t,去甲氯胺酮毒物代谢动力学方程为ρt=640.919 e-0.03t+1.023 e-0.001t+9.784 e-0.031t。血液中氯胺酮质量浓度达峰时间为(40.950±12.098)min,血峰质量浓度为(9.015±1.344)μg/mL,消除半衰期为(430.370±28.436)min。给药后30～240 min内氯胺酮在血清和尿液中的质量浓度之间具有动态平衡的中度相关性。家兔给药后30min出现中毒症状,120min后渐恢复正常。结论建立的氯胺酮毒物代谢动力学方程和参数...     

甲基苯丙胺和氯胺酮在家兔体内毒代动力学及相互影响

目的比较家兔单独静脉注射甲基苯丙胺、氯胺酮及二种药物联合静注时的毒物代谢动力学过程,评价二种药物毒代动力学的相互作用。方法单用甲基苯丙胺组以3mg/kg剂量家兔静脉注射甲基苯丙胺,单用氯胺酮组以30mg/kg剂量家兔静脉注射氯胺酮,合用组以相同剂量同时注射两种药物。分别于给药后不同时间点收集血浆标本,测定各时间点药物浓度,WinNonLin软件拟合毒代动力学房室模型并计算参数。结果甲基苯丙胺在家兔体内的毒代动力学过程呈一级动力学特征,符合单室模型,合用氯胺酮后不改变其模型类型。氯胺酮在家兔体内的毒代动力学过程呈一级动力学特征,符合单室模型,合用甲基苯丙胺后符合二室模型。结论甲基苯丙胺和氯胺酮可以相互延缓其在体内的消除过程,增加彼此在体内的吸收,从而延长作用时间。     

利用房水钾离子浓度推断死亡时间的实验研究

目的探讨利用房水中钾离子浓度进行死亡时间推断的可行性。方法30只家兔随机分为10组,以空气栓塞法处死后,于不同的死亡时间点分别采集房水和玻璃体;用Vitros 950干式自动生化仪对所有样本中的K+、Na+、Ca2+三种离子进行浓度测定;用SPSS统计软件对测定数据进行回归分析。结果房水中钾离子浓度变化与死亡时间呈高度相关,对应的回归方程为:PMI=1.572-0.597×[K+]+0.107×[K+]2-0.002×[K+]3。其相关系数(R2=0.95)明显高于同批样本的玻璃体钾离子浓度与死亡时间的相关系数(R2=0.5)。房水、玻璃体液的Na+、Ca2+浓度与死亡时间的相关性不明显。结论利用房水钾离子浓度推断死亡时间可获得较好的准确度。     

甲基苯丙胺在家兔体内的毒物代谢动力学研究

目的研究甲基苯丙胺及其代谢物苯丙胺在家兔体内的毒物代谢动力学行为。方法GC/MS法测定家兔灌胃甲基苯丙胺后不同时间点血、尿中甲基苯丙胺和代谢物苯丙胺浓度,采用3P97程序进行房室模型拟合以及毒物代谢动力学参数计算。结果甲基苯丙胺和苯丙胺在家兔体内的毒物代谢动力学过程均呈一级动力学特征,符合二室开放模型。甲基苯丙胺在家兔体内Cm ax为1.457 mg/L±0.094 mg/L,Tm ax为1.557h±0.078h,t1/2 ka、t1/2α和t1/2β分别为0.384h±0.052h、1.614h±0.036h和3.007h±0.430h,CL为1.769 L/h/kg±0.114 L/h/kg。甲基苯丙胺的毒物代谢动力学方程为:C t=2.767 e-0.746 t+1.454 e-0.234 t+4.119 e-1.746 t。结论甲基苯丙胺在家兔体内吸收、消除和代谢都较快。建立的甲基苯丙胺毒物代谢动力学方程和参数可为甲基苯丙胺分析的合理取样、从血药浓度推断服毒时间以及甲基苯丙胺滥用的法医学鉴定提供理论依据。     

阿维菌素在急性中毒死家兔体内的再分布研究

目的考察阿维菌素在急性中毒死家兔体内的再分布。方法按最小致死量一次性灌胃250mg/kg阿维菌素,HPLC法检测家兔死后0h、24h、48h和72h中阿维菌素的含量。结果给家兔一次性灌胃250mg/kg阿维菌素的临床死亡时间为120.6±9.2min(±s,n=10);测定了阿维菌素的致死血浓度和致死组织浓度;家兔死后0h~72h心血和各主要脏器组织中阿维菌素含量存在体内再分布现象;确定肝、肾、肺为最佳组织检材。结论阿维菌素在急性中毒死家兔体内的再分布数据,对法医办理此类案件具有重要参考价值。     

P物质在过敏性休克家兔胃肠道内的表达

目的观察P物质在过敏性休克家兔胃肠道组织中随时间变化的规律,探讨其在过敏性休克中的作用。方法 30只家兔随机分为实验组(24只)和对照组(6只)。实验组采用多人混合血清致敏家兔,建立过敏性休克模型。休克不同时间段(猝死即刻、休克0.5h、休克1h、休克2h)提取家兔胃、小肠、圆小囊。冰冻切片,应用免疫组化(IHC)SP法和原位杂交(ISH)方法进行P物质染色,BI-2000计算机图像分析系统进行图像分析,计算阳性积分光密度值(IOD),用SPSS11.5统计软件进行方差分析,SNK检验。结果与对照组相比,实验组各小组胃、肠、圆小囊P物质蛋白和mRNA表达明显增加,且随着休克时间的变化逐渐减弱(P0.001)。IHC方差分析结果为:胃组织F=198.008,肠组织F=56.796,圆小囊组织F=67.231;ISH统计学分析方差分析结果为:胃组织F=67.506,肠组织F=72.117,圆小囊组织F=216.798。结论家兔胃肠道P物质在过敏性休克后一段时间内(2h)均表达增高,随休克时间的延长逐渐下降。     

应用死后肾脏CT值变化规律推断死亡时间

目的检测死后不同时间点新西兰兔肾脏CT值(单位:Hounsfield Unit,HU),获得其死后变化规律,建立死亡时间推断方程。方法采用健康成年新西兰兔10只,利用耳缘静脉空气栓塞法处死后放入20℃恒温箱内保存,在死后0～168h内,采取每隔12h进行一次CT扫描,检测肾脏CT值随时间的变化情况,采用回归分析方法确定肾脏CT值与PMI的关系。结果 PMI在0～168h之内,肾脏CT值随PMI的延长呈现先增加后下降的趋势,使用曲线拟合分析,x:肾脏整体CT值,单位为HU;y:PMI,单位为h,其中二次方程的拟合效果最好,拟合回归方程为:y=2266.973-93.180x+0.974x~2(R~2=0.758,P 0.001)。结论本研究表明,肾脏CT值随着死亡时间的逐渐延长存在明显的死后变化规律,PMCT测量肾脏整体CT值可作为法医学推断PMI的新方法之一,具有很好的应用前景,值得进一步研究。     

Reduction of postmortem angiography-induced tissue edema by using polyethylene glycol as a contrast agent dissolver

Postmortem investigation is increasingly supported by computed tomography (CT) and magnetic resonance imaging, in which postmortem minimal invasive angiography has become important. The newly introduced approach using an aqueous contrast agent solution provided excellent vessel visualization but was suspected to possibly cause tissue edema artifacts in histological investigations. The aim of this study was to investigate on a porcine heart model whether it is possible to influence the contrast agent distribution within the soft tissue by changing its viscosity by dissolving the contrast agent in polyethylene glycol (PEG) as a matrix medium. High-resolution CT scans after injection showed that viscosities above c. 15 mPa s (65% PEG) prevented a contrast agent distribution within the capillary bed of the left ventricular myocardium. Thereby, the precondition of edema artifacts could be reduced. Its minimal invasive application on human corpses needs to be further adapted as the flow resistance is expected to differ between different tissues.     

Whole body postmortem angiography with a high viscosity contrast agent solution using poly ethylene glycol as contrast agent dissolver

Postmortem minimal invasive angiography has already been implemented to support virtual autopsy examinations. An experimental approach in a porcine model to overcome an initially described artificial tissue edema artifact by using a poly ethylene glycol (PEG) containing contrast agent solution showed promising results. The present publication describes the first application of PEG in a whole corpse angiographic CT examination. A minimal invasive postmortem CT angiography was performed in a human corpse utilizing the high viscosity contrast agent solution containing 65% of PEG. Injection was carried out via the femoral artery into the aortic root in simulated cardiac output conditions. Subsequent CT scanning delivered the 3D volume data of the whole corpse. Visualization of the human arterial anatomy was excellent and the contrast agent distribution was generally limited to the arterial system as intended. As exceptions an enhancement of the brain, the left ventricular myocardium and the renal cortex became obvious. This most likely represented the stage of centralization of the blood circulation at the time of death with dilatation of the precapillary arterioles within these tissues. Especially for the brain this resulted in a distinctively improved visualization of the intracerebral structures by CT. However, the general tissue edema artifact of postmortem minimal invasive angiography examinations could be distinctively reduced.     

死后血液流动对氯胺酮在家兔尸体内再分布的影响

目的观察分析静脉注射氯胺酮家兔死后血液流动对体内药物浓度再分布影响。方法雄性新西兰大白兔随机分为实验组2组（各24只）,对照组（8只）;实验组家兔经耳缘静脉注入40mg/kg氯胺酮,1.5h后处死,其中一组立即结扎主动脉,另一组不结扎;家兔尸体仰卧位室温下保存,分别于死后0、3、6、12、24、48、72和96h解剖并采取组织和体液样本;对照组静脉注射等量生理盐水,同样方法解剖取相同样本。所有样本采用GC/MS和GC-NPD法检测样品中氯胺酮含量。结果两个实验组家兔尸体放置96h内氯胺酮含量,除尿液各时间点与0h以及相邻时间点之间比较均有显著性差异（P〈0.05）外,两组家兔其余各类样本与0h以及相邻时间点比较均无显著性差异（P〉0.05）。除尿液外,各类样本两个实验组之间均无显著性差异（P〉0.05）;结扎组和不结扎组心血与外周血中氯胺酮含量比值分别为0.90~1.03和0.90~1.02。结论静脉注射氯胺酮家兔死后的血液流动不是体内氯胺酮发生再分布的主要机制。     

Determination of drug levels in larvae of Lucilia sericata (Diptera: Calliphoridae) reared on rabbit carcasses containing morphine

This study concerns the determination of morphine concentrations in fly larvae reared on rabbits administered different concentrations of morphine and a correlation between concentrations of the drug in larvae and tissues. Three rabbits (R1, R2 and R3) were given dosages of 12.5, 25.0 and 50.0 mg/h of morphine over a 3 h period via continuous ear artery perfusion. These dosages and time of perfusion were calculated to create tissue concentrations of morphine similar to those encountered in human death due to overdose. Morphine blood level plateau was attained after 1 h of perfusion. A fourth rabbit was used as a control. To evaluate drug concentrations, tissues were sampled using a coelioscopic technique. Approximately 400 eggs of Lucilia sericata, all of the same age category, were placed in eyes, nostrils and mouth of each rabbit carcass. Larvae and puparia were regularly collected from each rabbit for toxicological analysis. The concentrations of the drug in the tissues sampled were determined to be similar to those normally encountered in human overdoses and were correlated with the dosage of morphine that had been administered. Morphine was detected in all larvae and pupae fed on tissues from carcasses administered morphine, except for puparia from the colony fed on the R1 animal which received 12.5 mg/h dosage of morphine. All samples from the control rabbit were negative for morphine. Concentrations of morphine in larvae reared on rabbit carcasses containing morphine were 30 to 100 times lower than the concentrations found in the tissues. A correlation between the tissue concentrations and larval concentrations was found in only 3rd instar larvae (80 to 140 h following hatching). No correlations were found between administered dosages, tissue concentrations and younger larvae, prepuparial larvae or puparia.     

Scavenging behavior of Lynx rufus on human remains during the winter months of Southeast Texas

Animal-scavenging alterations on human remains can be mistaken as human criminal activity. A 32-day study, documenting animal scavenging on a human cadaver, was conducted at the Southeast Texas Applied Forensic Science facility, Sam Houston State University, Huntsville, Texas. A Stealth Cam Rogue IR was positioned near the cadaver to capture scavenging activity. An atypical scavenger, the bobcat, Lynx rufus, was recorded feeding on the cadaver. Scavenging by bobcats on human remains is not a predominant behavior and has minimal documentation. Scavenging behaviors and destruction of body tissues were analyzed. Results show that the bobcat did not feed on areas of the body that it does for other large animal carcasses. Results also show the bobcat feeds similarly during peak and nonpeak hours. Understanding the destruction of human tissue and covering of the body with leaf debris may aid forensic anthropologists and pathologists in differentiating between nefarious human activity and animal scavenging.     

Determination of drug levels in larvae of Protophormia terraenovae and Calliphora vicina (Diptera: Calliphoridae) reared on rabbit carcasses containing morphine

Two species of blow flies (Diptera: Calliphoridae) were reared on tissues from rabbits administered different dosages of morphine. These species, Protophormia terraenovae and Calliphora vicina are among the first wave of insects colonizing a dead body. Two series of 3 rabbits were given dosages of 10, 20, and 40 mg/h of morphine over a 3 h period via ear artery perfusion. A morphine blood level plateau was attained after 1 h of perfusion. Two other rabbits were used as controls. Samples of tissues collected from rabbits using a coelioscopic technique were determined to have morphine concentrations similar to those encountered in human overdoses and were correlated with dosages of morphine administered. All samples from control rabbits were negative for morphine. Larvae and puparia of both species were regularly collected from each rabbit for toxicological analysis. Concentrations of morphine in larvae reared on rabbit carcasses containing morphine were significantly lower than concentrations found in the tissues. There was a decrease in concentration in morphine observed in transition from feeding 3rd instar larva to puparium. A correlation between larval concentration and tissue concentration was found only in feeding 3rd instar larvae.     

Preliminary observations of the effect of methamphetamine in decomposing tissues on the development rate of Parasarcophaga ruficornis (Diptera: Sarcophagidae) and implications of this effect on the estimations of postmortem intervals.

Larvae of Parasarcophaga ruficornis (Fabricius) (Diptera: Sarcophagidae) were reared on tissues from rabbits administered different dosages of methamphetamine to study the effects of this drug on development of this species. The rabbits were given 37.5, 71.4, and 142.9 mg of methamphetamine via ear vein infusion. From Hours 30 to 60, larvae feeding on tissues from rabbits receiving 71.4 and 142.9 mg of methamphetamine developed more rapidly than larvae from the control colony and those feeding on tissues from the rabbit receiving 37.5 mg of methamphetamine. The time required for pupariation was significantly greater for colonies fed on tissues from methamphetamine-dosed rabbits than for the control. These differences were sufficient to alter postmortem interval estimates based on larval development by up to 18 h and estimates based on puparial development by up to 48 h. The presence of methamphetamine or amphetamine could not be detected in Diptera larvae in this experiment using radioimmunoassay techniques, as there was a nonspecific reaction, resulting in a false positive.     

Determination of drug levels and the effect of diazepam on the growth of necrophagous flies of forensic importance in southeastern Brazil.

Larvae of Chrysomya albiceps (Wiedemann) and Chrysomya putoria (Wiedemann) (Diptera: Calliphoridae) were reared on tissues from rabbits administered twice the lethal dosage of diazepam in order to study the effects of this drug on the development of these two species. The rabbits were given 50mg of diazepam via ear vein infusion. From 18 to 54h, larvae feeding on tissues containing the drug developed more rapidly than larvae from the control colony for both fly species. The time required for pupariation and adult emergence was significantly greater for colony fed on tissues from diazepam dosed rabbits than for the control ones. These differences are significant for they are large enough to alter the estimate of postmortem interval based on fly development. The presence of diazepam could be detected through gas chromatography-mass spectrometer (GC-MS) in all rabbit samples and in almost all diptera samples in this experiment.