溺死鉴定中硅藻检验的应用

在法医学检案中,溺死诊断以及入水地点的判定一直是重点和难点之一,硅藻检验被认为是一种相对可靠的诊断溺死的方法,而根据硅藻的群落特征推断其入水区域具有一定的可信度。对不同水域内硅藻进行研究,可为溺死鉴定及入水区域的判定提供参考。本文就硅藻相关的生物学特性、检验方法等相关的国内外研究进展进行综述,供法医学工作者在相关科研和检案实践中参考。     

溺死的法医学鉴定

溺死的鉴定一直是基层法医鉴定工作中的难点,这是由于大部分溺死案例的特征性尸检所见很少,同时国际上很多学者对溺死的实验室检验存有疑义。本文查阅了国内外相关文献并结合作者多年来对溺死案例的实际鉴定经验,对溺死的法医学鉴定作出较系统的综述。     

溺死法医学鉴定的研究新进展

综述了近年来在硅藻检验、水中浮游生物叶绿素（A）检测、血液化学和组织化学检验等方面的最新文献报道,并对各种溺死检验方法的优缺点进行了评价：在硅藻检验中,硝酸乙醇法、破机罐法及微波消解法,可缩短检验时间,提高办案效率;酶消化法及PCR法硅藻检出率高,适用于可疑水样中硅藻密度低等情况。早期器官组织中浮游生物叶绿素（A）、血液和组织中其他生化指标,可作为鉴定溺死的重要参考。微量元素锶检测可用于鉴定海水中溺死。另外,硅藻及其他浮游生物遗传多态性片断PCR,可望成为新的、灵敏的溺死检测方法。     

溺死的法医学检验现状及进展

本文概括阐述了近年来,国内外学者将硅藻的检验、内脏异物颗粒和微量元素成分的检验、血液化学的检验、电子显微镜的观察等方法应用于溺死的诊断,试图为溺死的法医学鉴定提供准确的诊断指标。     

急性酒精中毒对大鼠溺死后肺组织硅藻检出的影响

目的急性酒精中毒对大鼠溺死后肺组织硅藻检出的影响。方法将40只大鼠随机分为5组,进行酒精灌胃,灌注量分别为:正常组(0m L/kg)、低剂量组(7m L/kg)、中剂量组(15m L/kg)、高剂量组(22m L/kg)、死后抛尸组(0m L/kg)。观察各组大鼠行为变化、溺水时生存能力及死后肺组织中硅藻检出量。结果高剂量组呼吸出现浅慢,呼吸停止时间减少(P0.05)。酒精灌注各组大鼠攀附时间均减少(P0.05),肺组织硅藻检出量均减少(P0.05)。结论急性酒精中毒可以导致大鼠溺死后肺组织硅藻检出量减少。     

浮游生物PCR检测及其在溺死鉴定中的研究进展

溺死鉴定是法医学中的重点和难点之一,目前在相关法医学案件中,主要采用法医病理学尸检与传统硅藻检验等方法综合分析进行鉴定。传统硅藻检验存在灵敏性较低,易于污染等不足。采用PCR法检测尸体不同脏器组织中是否存在水中浮游生物的DNA标记,适用范围广,信息量丰富,灵敏性和特异性较高,有较好的法医学应用前景,有望成为鉴定溺死的新方法。本文对相关研究进展进行综述,为相关研究和实践参考。     

大鼠机械性损伤后皮下肌肉出血的病理学观察

目的 观察生前机械性损伤后不同时间皮下肌肉出血的病理形态学变化.方法 56只SD大鼠随机分成生前损伤组(48只)、死后损伤组(4只)和正常对照组(4只);生前损伤组按不同时间再分为12组,建立机械性损伤模型;用HE及普鲁干蓝染色法观察皮下肌肉出血的病理形态学变化.结果 HE染色:生前损伤6～24h,损伤区见较多红细胞及...     

实时荧光定量PCR检测硅藻UPA基因在溺死诊断中的研究

目的建立硅藻UPA条形码基因的实时荧光定量PCR检测方法,探讨其在溺死诊断中的应用价值。方法对Gene Bank中登录的硅藻UPA基因序列进行比对获得同源序列,据其设计硅藻门通用引物。对2种人体常见共生菌(大肠杆菌、双歧杆菌)、3种浮游细菌、15种浮游藻类、32具尸体(其中生前溺水死亡28例,死后抛尸1例,陆地死亡3例)的组织样本(肺、肝、肾)及尸体发现地水样提取DNA,采用设计的引物进行特异性、灵敏度、重复性试验,分析检材中硅藻检出情况,统计硅藻阳性率,以上述组织样本的微波消解-真空抽滤-自动扫描电镜法检测结果对建立的q PCR检测方法进行比较评估,比较该方法与PCR-毛细管电泳检测法的灵敏度。结果引物UPA99仅对硅藻标准株(针杆藻、舟形藻、直链藻、小环藻、菱形藻)DNA具有扩增,扩增产物熔解曲线平稳,峰尖且窄,熔解温度为(87±1)℃。以p MD18-T重组质粒为标准品,检测区间为1.56×10~2-1.56×10^-5ng/μL,建立实时q PCR方法的灵敏度为1.56×10^-5ng/μL,而PCR-CE方法的灵敏度为1.56×10-3ng/μL。批间及批内变异系数均低于2%,具有较高的重复性和稳定性。对于生前溺水尸体肺、肝、肾的检出率依次为89.3%,71.4%,64.3%。结论基于硅藻UPA基因设计通用引物,建立的q PCR硅藻检验法特异性高、灵敏度高、重复性好,应用于溺死诊断具有较好的应用前景。     

PCR-DHPLC法检测硅藻SSU基因在溺死鉴定中的应用

目的采用PCR-DHPLC法检测硅藻SSU基因,评估其在溺死鉴定中的应用价值。方法 60只实验兔随机分为生前溺死（水中溺毙）、死后入水（空气栓塞致死后入水）、对照组（空气栓塞致死后不做处理）;溺死人体脏器组织;取各组织检材提取硅藻DNA,PCR扩增硅藻特异的核糖体小亚基（SSU）片段,用琼脂糖凝胶电泳检测、DHPLC检测分析。结果 6份硝酸消化法检测阴性的溺死人体器官组织检材经PCR及琼脂糖凝胶电泳检出5例阳性。生前溺死组肺、肝、肾硅藻检出率分别为100%、90%、85%,死后入水组仅肺检出硅藻（15%）,对照组各组织均为阴性;生前溺死组检出率明显高于死后入水组（P〈0.05）。10份溺死人体器官组织检材采用DHPLC法检出硅藻种类明显多于微波消解-扫描电镜法（P〈0.05）。脏器检出硅藻种类与溺死点水样一致。结论采用PCR-DHPLC法检测硅藻SSU基因,有助于溺死鉴定和溺死地点的推断,具有法医学应用价值。     

微波消解-扫描电镜联用法在溺死诊断中的应用

目的探讨微波消解-扫描电镜联用法在溺死诊断中的应用价值。方法收集已知死因的尸体标本105例,其中水中尸体85例(生前溺死70例,死后抛尸入水15例),陆地自然死亡尸体20例。水中死亡案例同时收集落水处水样。分别用微波消解-扫描电镜联用法(方法 A)和硝酸破机-光镜联用法(方法 B)对上述尸体的离体肺、肝、肾、骨髓组织及水样进行硅藻定性、定量检测。结果①溺死尸体的肺、肝、肾、骨髓中及落水处水样硅藻检出率:A法分别为100%、94.3%、92.9%、82.9%、100%,硅藻检验阳性率为100%;B法分别为90%、62.9%、51.4%、28.6%、92.9%,硅藻检验阳性率为65.7%。②两种方法检出的硅藻种类与落水处水样中硅藻的种类均一致。③两种方法在死后入水尸体离体的肺中也检出少量硅藻(<3个/2g肺组织),但在死后入水尸体的其它脏器及陆地自然死亡尸体脏器中均未检出硅藻。结论微波消解-扫描电镜联用法较硝酸破机-光镜联用法对尸体离体组织脏器中的硅藻检出率高,方法灵敏,定性准确。     

Fatal accidental hanging by a high-chair waist strap in a 2-year-old girl

High chairs are commonly used to feed children after 6 months. Related injuries are oftentime minor and rarely leading to death. We describe a case of a 2-year-old female child who used to jump alone on her high chair and also had the habit to fasten the straps by herself. Her mother found her hanging by the waist straps. A thorough investigation showed that she climbed her high chair and fastened the waist straps but not the crotch one. The girl slid down into the seat, trapping her neck in the waist straps and thus resulting in hanging. In here, we concluded that the victim's death was caused by asphyxia, itself, caused by accidental hanging. The present case is of a special interest because of the rare similar cases reported. This case suggests that a correct restraint use and a close supervision would have prevented such a fatal issue.     

东莞溺死案多发河段硅藻种群分布及其法医学意义

目的调查东莞溺死案多发河段硅藻种群分布,探讨其在溺死地点推断中的意义。方法于2009年6月至9月收集东莞市东江沙田、道滘、麻涌、石碣、石龙、茶山和企石共7个河段采样点江水样本126份,并收集2例已知落水地点溺死尸体;制作各样本硅藻涂片,计算样本间Sprensen相似系数及弦平方距离(SCD),并进行聚类分析。结果 126份水样中共鉴定出70种硅藻,其中优势度>0.02的优势种群有4种;2个案例样本分别与道滘和石碣河段样本的相似度最高,与实际落水地点基本一致。结论建立区域性溺死多发河段硅藻数据库,利用Sprensen相似系数及SCD值及聚类分析进行落水地点推断具有一定可行性。     

微波消解-扫描电镜联用检测脏器内硅藻

目的介绍一种微波消解-扫描电镜联用检测脏器内硅藻的新方法。方法大白兔30只,随机分为生前溺死组（n=15）和死后溺尸组（n=15）。提取兔肺、肝、肾、股骨骨髓和现场珠江水样,采用建立的微波消解-扫描电镜联用法检测脏器组织和水样中的硅藻,并与硝酸乙醇消解-扫描电镜联用的方法进行比较。结果生前溺死组的兔肺、肝、肾、股骨骨髓组织中大多数观测到与现场珠江水样一致的硅藻,微波消解-扫描电镜联用法检测脏器内硅藻的平均含量分别为：2505.2个/2g肺,18.7个/10g肝,6.5个/10g肾,6.3个/0.5g骨髓;肺与肝、肾、骨髓检出硅藻的阳性比例为86.7%,脏器硅藻检出含量和硅藻检验阳性比例均明显高于硝酸乙醇消解-扫描电镜联用法所测值。死后溺尸组的兔脏器组织均未观测到硅藻。结论微波消解-扫描电镜联用法检测脏器内硅藻,高效、安全、环保,硅藻检验灵敏度高,降低了劳动强度,提高了定性定量分析准确度,且能有效避免污染,在法医学溺死鉴定中具有良好的应用价值。     

Postmortem chest computed tomography for the diagnosis of drowning:a feasibility study

It may be difficult to distinguish the cause of death in drowning cases without specific findings. The aim of this study was to explore the forensic value of thoracic postmortem computed tomography (PMCT) using routine images and three-dimensional (3D) image reconstructions. The imaging data of PMCT examinations of six drowning cadavers, aged 21–54 years, were analyzed. Twelve victims of sudden death from coronary artery disease (CAD) were chosen as a control group. After 3D bilateral lung images were reconstructed using image processing software, an interactive medical image control system was used to measure and analyze parameters including lung volume, lung volume ratio, mean CT value of the whole lung, and lung CT value distribution curves. Lung volume and lung volume ratio were used to assess the shape changes of the lung. Lung CT value distribution curves showed the corresponding number of pixels of the different CT values in the lung image. Lung volume was not significantly larger in drowning cases (mean 2 958 cm³) than in controls (mean 2 342 cm³). Lung volume ratio values in the drowning group (mean 0.3156) were greater than those in the control group (mean 0.2763); (P = 0.02). There was no significant difference between the drowning and control group in the mean CT value of the whole lung. There were differences between lung CT value distribution curves in drowning victims and controls, with drowning victims showing a single peak and CAD cases showing a bimodal distribution. Thoracic PMCT is helpful for the forensic medical diagnosis of drowning. Lung volume ratio and lung CT value distribution are potential indicators to distinguish between drowning and CAD.     

硅藻检验方法综述

水中尸体的调查在法医学检案中占了重要的一部分。水中尸体未必就意味着其死亡原因是溺死,也可以由其他原因引起,例如死后入水。实际上,尸体现象很难证明死亡的原因。所以,关于受害者是否为"真的"溺死的问题常常不容易解决。目前,硅藻检验被认为是溺死诊断的"金标准"。通过硅藻的定性定量分析,不仅可以对死亡原因有更直接的判断,也可以指向可能的溺死地点。本文介绍国内外硅藻检验的样本采集、检验方法、结果评价的研究进展,并对硅藻检验研究进行展望。     

Morphometric Investigation of Death by Asphyxia

Abstract:  The aim of this study was to investigate the possibility of distinguishing deaths by asphyxia from those due to natural causes by comparing morphometric measurements in lungs. The study population comprised 27 subjects: 14 cases of death by asphyxia (hanging or drowning) and 13 cases of sudden natural death. Eighty parenchyma sections were used for each subject. Data were collected by computerized image analysis. Measurements aimed at quantifying, as percentages, pulmonary parenchyma (mean values of positive-fraction areas [PFA] and their standard deviations). Subjects who died of natural causes and of drowning showed a relative internal homogeneity compared to those who hanged. Results show significant discrimination between drowned subjects and those dying of natural causes (mean of PFA p  = 0.01) and between hanged and drowned subjects (SD of PFA p  = 0.04). Attention must be paid to the possible role played by senile emphysema. The method is proposed as a complementary tool in forensic cases.     

The Diagnostic Value of Quantitative Assessment of Diatom Test for Drowning: An Analysis of 128 Water‐related Death Cases using Microwave Digestion‐Vacuum Filtration‐Automated Scanning Electron Microscopy

The value of diatom test for the diagnosis of drowning remains controversial. The conventional forensic diatom test with low sensitivity is not a useful tool to provide accurate information about diatom in the tissues and organs. To improve the sensitivity of the diatom test, we developed a novel method called the Microwave Digestion‐Vacuum Filtration‐Automated Scanning Electron Microscopy (MD‐VF‐Auto SEM) method which resulted in a high recovery of diatoms. In this article, we analyzed 128 water‐related death cases. Our results showed that the MD‐VF‐Auto SEM method could achieve a much higher positive rate (0.97) in drowning cases. Large amounts of diatoms are retained, even concentrated, in the lung tissues during the intense breathing movement in drowning process. This might be useful for the diagnosis of drowning. Our research indicates that the MD‐VF‐Auto SEM method would be a valuable methodology in the study of diatom test for the forensic community.     

广东珠江水域硅藻种类调查

目的应用扫描电镜对广东珠江水域水中硅藻进行观察,获得珠江水域硅藻种类情况及分布状况,结果有助于法医学水中尸体死亡原因及落水水域的推断。方法收集了广东省珠江水域19个取水点的水样,采用勒福特王水进行消解,并应用扫描电镜进行观察。结果 (1)19个采样点共检出直链藻、卵形藻、小环藻、菱板藻、菱形藻、双菱藻、针杆藻、冠盘藻、舟形藻、曲壳藻、圆筛藻、短缝藻、桥弯藻、海链藻、布纹藻、波缘藻、等片藻、辐节藻、双壁藻、异极藻和羽纹藻21种硅藻,分属于羽纹纲和中心纲。(2)获得19个采样点硅藻分布数据资料。结论 (1)珠江水域硅藻种类具有一定的特点。(2)不同河域硅藻种类、数量的差异有助于法医学推断溺死落水地点。     

成都市主城区水中尸体多发河流区段硅藻分布

目的研究成都市主城区水中尸体多发河流区段所含硅藻的种属分布。方法采集2014年10月成都市(锦江区、金牛区、青羊区、武侯区、成华区)5条河流区段共39个采水点水样标本,制作硅藻涂片后运用生物显微镜及数码显微采集系统对水样中硅藻种属分布及构成比进行研究。结果成都主城区所检水域共检见硅藻种属21种,各水域硅藻优势种属及构成比存在差异。各河流区段上、中、下游采样点均存在差异藻属。结论初步建立了成都主城区河流区域性硅藻种属图谱及区段性种属分布构成比数据库,对分析评价硅藻检测在案件侦查中推断落水点具有特殊意义。     

Forensic Case Reports Presenting Immersion Pulmonary Edema as a Differential Diagnosis in Fatal Diving Accidents

Immersion Pulmonary Edema (IPE) reduces the transport of gases over the respiratory membrane due to edema in the interstitium and respiratory zones. IPE has previously been described in both swimmers and divers, with a few known fatal cases. We have reviewed 42 SCUBA and snorkeling‐related drowning deaths, and through a thorough analysis of each case, including both diving physiology and forensic pathology, we present IPE as a differential diagnosis to drowning in four cases. Our findings propose that; absence of watery content in the stomach and conducting airways, and liquid filled lungs without hyperexpansion, may be compatible with IPE. We suggest that IPE should be considered in cases where witness testimony reveals; no obvious signs of aspiration and rapid respiratory deterioration despite continuous breathing through an appropriate air source. The diagnosis should be based on the overall impression, including both the autopsy findings and the circumstances regarding the accident.